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why do oceanic plates subduct under continental plates
When two oceanic
plates collide one oceanic plate is eventually subducted under the other. Where one plate slides under the other is referred to as the 'subduction
zone'. As the subducting plate descends into the mantle where it is being
gradually heated a benioff zone is formed. This benioff zone is a zone of
shallow,intermediate and deep focused earthquakes. Some deep focused earthquakes
that occur at ocean ocean- collision boundaries can be as deep as 670 kilometres. As the subducted plate descends into the mantle it is gradually heated allowing
the formation of magma. The magma that forms is andesitic in composition
and begins to form when the subducted plate reaches a depth of 100 kilometres. This andesitic magma is formed from the partial melting of the asthenosphere
just above the subduction zone. This partial melting of the subducting plate
is due to the loss of water as it descends into the mantle. The andesitic
magma is now less dense than the surrounding material so it rises through
the crust and erupts to form an arc of volcanoes called an island arc. The
distance between the trench and the island arc depends greatly upon where
the subducting plate reaches the 100 kilometer depth.
If the subduction angle
is steep then the distance between the arc and the trench will be short. If
the suduction angle is shallow the distance is longer. The main features
are indicated in the diagram below. The swell is seen by a bulge in the in
the downgoing plate where it is subducted into the mantle. where the plate
subducts into the mantle is known as the trench. the forearc ridge contains
highly deformed sedimentary and metemorphic rock. The backarc region is located
behind the arc and can be compressed or extended.
1. Divergent boundaries There are places on earth where two plates are separating or spreading apart, such as at oceanic ridges. Rift valleys and occur when the lithosphere is under tensional stress. At spreading zones, new magma comes up from the mantle, pushing two plates apart and adding new material at their edges. Spreading zones are usually found in oceans along with mid-ocean ridges. For example, the North American and Eurasian plates are spreading apart along the mid-Atlantic ridge. As the new material flows out of the ridge, it pushes the existing ground floor out, until it eventually sinks under another plate, which leads us into a different type of boundary.
Earthquakes with low Richter along boundaries with normal fault motion tend to be shallow focus. These quakes can have focal depths of less than 20km. This indicates the brittle lithosphere must be thin along the diverging plate boundaries. 2. Transform boundaries These are found where plates slide past one another. The San Andreas Fault is an example of a transform -fault plate boundary along the north western Mexican and California coast. Earthquakes along transform boundaries show strike-slip motion on the faults, they form fairly straight linear patterns and tend to be shallow focus earthquakes with depths usually less than about 100 km. Richter magnitudes could be large. As seen in the image above, the trees (they look like small dots) in the aerial view of San Andreas fault have been offset by the slipping of the plates. The North American Plate to the right and the Pacific Plate to the left. 3. Convergent boundaries Convergent boundaries are the place where two tectonic plates converge (i. e. two plates move toward each other).
These zones tend to be where compressional stresses are active and this results in thrust or reverse faults being common. Converging plate boundaries are of two types: occur where oceanic lithosphere is pushed beneath continental or oceanic lithospheres. Where two plates converge at an oceanic trench a subduction boundary is formed as cold oceanic lithospheres are pushed back down into the mantle. This happens because the oceanic plate is denser than the continental plate so, as they move together, the oceanic plate is forced underneath the continental plate. In this case, one plate overrides, or "subducts" the other, pushing it slowly downward into the mantle where it melts to form magma. A subducted lithosphere remains cold and brittle as it descends and can fracture under compressional stress. These fractures generate earthquakes that define a zone of quakes at increasing focal depth under the overriding plate. This zone is called the. Depths of up to 700km are reached in the Benioff Zone. Examples of subduction zones are found along the northwest coast of the United States, Mexico, western Canada, southern Alaska, South America, Central America, Japan, Philippines, Caribbean Islands and the Aleutian Islands. where two plates of continental lithosphere collide result in fold-thrust mountain belts.
The continental crust is squashed together as the plates push together and is forced upwards. This is called folding. are created by this process of folding. Where two continental plates converge and push towards each other fold mountains can also be formed. This is how mountain ranges such as the Himalayas and the Alps were formed. Earthquakes occur due to the thrust faulting and range in depth from shallow to about 200 km. Examples are found along the Himalayan Belt into China, along the Northern edge of the Mediterranean Sea through Black Sea and Caspian Sea into Iraq and Iran. Convergent boundary zones are characterized by deep-ocean trenches, shallow to deep earthquakes, and mountain ranges containing active volcanoes. In general, where an oceanic and a continental plate collide, the denser oceanic plate will be forced under (subduction) the other.
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Where should buffers go? modeling riparian habitat connectivity in northeast KansasAuthor(s): Gary Bentrup; Todd Kellerman
Source: Journal of Soul and Water Conservation, Volume 59, Number 5: 209-215
Publication Series: Miscellaneous Publication
PDF: View PDF (0.98 MB)
DescriptionThrough many funding programs, riparian buffers are being created on agricultural lands to address significant water quality problems. Society and landowners are demanding many other environmental and social services (e.g., wildlife habitat and income diversification) from this practice. Resource planners therefore need to design riparian buffer systems in the right places to provide multiple services. However, scientific guidance for his is lacking. We developed a geographic information system (GIS)-based assessment method for quickly identifying where buffers can be established to restore connectivity of riparian areas for the benefit of terrestrial wildlife. An area in northeastern Kansas was selected to evaluate this tool. Species with limited dispersal capabilities were used as indicators for riparian connectivity, To improve connectivity, results indicated that 22 percent of the perennial stream length in the study area would need riparian buffers. This coarse-filter approach appears to be appropriate for large area planning and can be used singly or in combination with other GIs-guided resource assessments to guide riparian buffer design and implementation.
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CitationBentrup, Gary; Kellerman, Todd. 2004. Where should buffers go? modeling riparian habitat connectivity in northeast Kansas. Journal of Soul and Water Conservation, Volume 59, Number 5: 209-215
KeywordsConnectivity, corridors, fragmentation, geographic information systems (GIS), riparian buffers, wildlife
- Tool time: melding watershed and site goals on private lands
- Spatial and Temporal Relationships of Old-Growth and Secondary Forests in Indiana, USA
- UTOOLS: microcomputer software for spatial analysis and landscape visualization.
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To study hollows of living trees as the natural habitat of Cryptococcus neoformans in an endemic area of cryptococcosis in the northeastern Brazilian region, samples of decaying wood were collected inside the hollows, plated on niger seed agar and inoculated into mice and hamsters. Identification of C. neoformans was based on morphological and physiological tests. Canavanine-glycine-bromothymol medium was used to screen the varieties and Crypto Check Iatron Kit to serotype the isolates. For a period of 29 months C. neoformans var. gattii serotype B was isolated repeatedly from the hollow of a pottery tree (Moquilea tomentosa), pointing to the natural occurrence of C. neoformans var. gatti in decaying wood forming hollows in living trees. Evidence for a natural habitat of the variety gattii other than that related to Eucalyptus camaldulensis are discussed.
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Choose a citation style from the tabs below | <urn:uuid:6fc44f32-be3b-4758-a987-19745bf0226c> | 2.921875 | 221 | Academic Writing | Science & Tech. | 25.23 | 95,578,750 |
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Unique wing scale photonics of male Rajah Brooke’s birdwing butterflies
© The Author(s). 2016
Received: 9 June 2016
Accepted: 4 August 2016
Published: 12 August 2016
Ultrastructures in butterfly wing scales can take many shapes, resulting in the often striking coloration of many butterflies due to interference of light. The plethora of coloration mechanisms is dazzling, but often only single mechanisms are described for specific animals.
We have here investigated the male Rajah Brooke’s birdwing, Trogonoptera brookiana, a large butterfly from Malaysia, which is marked by striking, colorful wing patterns. The dorsal side is decorated with large, iridescent green patterning, while the ventral side of the wings is primarily brown-black with small white, blue and green patches on the hindwings. Dense arrays of red hairs, creating a distinct collar as well as contrasting areas ventrally around the thorax, enhance the butterfly’s beauty. The remarkable coloration is realized by a diverse number of intricate and complicated nanostructures in the hairs as well as the wing scales. The red collar hairs contain a broad-band absorbing pigment as well as UV-reflecting multilayers resembling the photonic structures of Morpho butterflies; the white wing patches consist of scales with prominent thin film reflectors; the blue patches have scales with ridge multilayers and these scales also have centrally concentrated melanin. The green wing areas consist of strongly curved scales, which possess a uniquely arranged photonic structure consisting of multilayers and melanin baffles that produces highly directional reflections.
Rajah Brooke’s birdwing employs a variety of structural and pigmentary coloration mechanisms to achieve its stunning optical appearance. The intriguing usage of order and disorder in related photonic structures in the butterfly wing scales may inspire novel optical materials as well as investigations into the development of these nanostructures in vivo.
Butterflies are a hallmark of biodiversity and multifunctionality in nature. Of particular beauty are the birdwing butterflies of Australasia, which are noted by their exceptional size and a birdlike flight [1, 2]. An especially attractive butterfly is Rajah Brooke’s birdwing, Trogonoptera brookiana, the national butterfly of Malaysia. However, a detailed explanation of the striking coloration has yet to be made.
Recent studies on butterfly coloration have revealed a multitude of optical mechanisms that strongly alter the composition of incident light and reflect strong colors. Pigments are generally the major means to create color. The pigments encountered in butterflies are rather family specific. For instance, pterins are prominently encountered in the Pieridae , ommochromes are the pigments of the Nymphalidae , while papiliochrome pigments have been only found in Papilionidae [5–8]. The pigments are dispersed in scales that cover butterfly wings like tiles on a roof. A butterfly wing scale basically consists of a lower lamina, which is essentially a thin plate with thickness 100-200 nm, connected by pillar-like trabeculae to the upper lamina, which is made up of an array of parallel ridges, with interdistance 1-2 μm, and connecting cross-ribs .
The fine structure of the scales often creates structural coloration. For instance, the lower lamina of the scales universally acts as a thin film reflector [10, 11]. Furthermore, the ridges of the upper lamina are built of lamellae, which in most Morpho species have extensive overlap [12, 13]. The stacked lamellae then act as optical multilayers, which create the butterflies’ striking blue-metallic reflections. Multilayers with perforations exist in the scale lumen of many lycaenids [14, 15]. Intricate structures, acting as three-dimensional photonic crystals, have been demonstrated in several lycaenid as well as papilionid species [16–19].
We recently reported the coloration mechanisms of the Ornithoptera, a genus of birdwings closely related to Trogonoptera sp. , with colorful scales consisting of a large membrane stack that acts as a chirped multilayer , where the reflected light is filtered by papiliochrome pigments. A previous study also reported the intriguingly complex ultrastructure of the strongly green reflecting wing scales of the birdwing butterfly T. brookiana . The anatomy of the birdwing scales has inspired the production of advanced materials via replication into inorganic materials [21–24]. However, we found that the latter papers contain confusing data and erroneous identifications of the scales of T. brookiana. Here we specifically focus at the optics of T. brookiana’s green reflecting scales, but we also analyze the interplay of pigmentary and structural coloration realized in other wing scale types, using spectrophotometry, imaging scatterometry, and transmission and scanning electron microscopy. We demonstrate that the lower lamina of the white and black scales acts as a thin film blue reflector and that the ridges of the blue scales and red hairs function as multilayer reflectors. The uniquely structured green-iridescent scales contain complex three-dimensional photonic crystals, the optical signature of which could be understood by applying finite-difference time-domain modelling.
Overall appearance of Trogonoptera brookiana
The underside of the wings is mainly dark-brown, with a few radiating, vivid-blue lines. A row of yellow-green chevrons with blue borders is present in the middle of the forewings. The hindwings are mainly black with at the outer rim a row of white spots. Red patches surround the thorax (Fig. 1b).
We measured the reflectance spectra of the various colored areas with a bifurcated fiber-probe spectrophotometer, which yielded intriguing spectral differences, especially for the green patches (Fig. 1c-f). Below we describe the very different pigmentary and structural aspects that contribute to the different colors, and we explain the resulting optical effects.
Thin films in the white and black scales
To ascertain the structure of the scales of the whitish wing areas of T. brookiana, we performed scanning electron microscopy. The white cover and ground scales as well as the black ground scales showed the common papilionid wing scale structure, with a disordered cross-rib lattice connecting regularly spaced ridges (Fig. 2c-e; see further [5, 26, 27]).
The reflectance spectra measured of black scales (Fig. 2f, #3) resembled that of a white cover scale when on a black ground scale (Fig. 2f, #2) except for a much lower amplitude. The latter is evidently due to a high concentration of melanin in the scales’ upper lamina, which strongly reduces the light flux reaching the lower lamina as well as filters the reflected light flux. The lower lamina’s thickness of ~200 nm, suggested by the reflectance spectrum, was confirmed by scanning electron microscopy (Fig. 2e).
Thin film reflectors, like those encountered in soap bubbles, usually reflect incident light very directionally, but this is not the case for the scales when illuminated from the side of the upper lamina, because the disordered cross-rib lattice acts as a diffuser. This was directly demonstrated by imaging scatterometry, using a narrow aperture illumination, which yielded a broad, diffuse pattern with a faint horizontal line caused by light diffraction at the ridge grating (Fig. 2g).
Pigmentary and structurally colored red hairs
To further investigate this, we performed scanning electron microscopy (Fig. 3b, c). As found in other cases, the ventral and collar hairs have a more or less cylindrical shape [9, 28]. The surface of the hairs featured prominent longitudinal ridges, very similar to the ridges of the white and black wing scales (e.g., Fig. 2c-e). However, in the cylindrical hairs the ridges are present along the complete circumference, while in the wing scales the ridges are only present in the upper lamina; the lower lamina is an approximately flat plate. As in the wing scales, the ridges of the hairs consist of overlapping lamellae. Notably however, the lamellae of the collar hairs overlap each other much more than those of the ventral hairs. This reminds us of the case of the yellow and orange wing scales of various pierid butterflies where overlapping ridge lamellae create UV-reflecting multilayers [29–32]. The UV-reflectance peak of the collar hairs has clearly the same structural basis.
Imaging scatterometry on wing scales with ridge multilayers demonstrated that the parallel ridges can act as a diffraction grating [32–34] (see also Fig. 2g). To investigate whether the hairs behave similarly, we performed scatterometry on single, isolated hairs (Fig. 3d). The scatterograms obtained from the two hair types both showed a colorful, line-shaped pattern perpendicular to the hair axis, clearly due to diffraction by the parallel ridges. The additional vague, diffuse red background is due to randomly scattered light filtered by the short-wavelength absorbing pigment in the connecting cross-ribs and additional underlying structures (cf. the scatterogram of Hebomoia glaucippe; Fig. 3c of ref. ).
Multilayered ridges in the blue scales
As noted above, imaging scatterometry of wing scales with multilayered ridges generally yield characteristic, line-shaped scatterograms. However, scatterograms of the blue scales of T. brookiana had a rather different appearance. Illumination with a narrow aperture beam yielded a reflected light beam with a restricted spatial distribution (Fig. 4c), indicating a special scale structure that reflects directionally.
We performed electron microscopy to unravel the structural basis of the blue scales’ colors. Somewhat surprisingly, scanning electron microscopy showed that the scale ridges consist of elaborate stacks of lamellae, similar to the well-known Morpho ridge multilayers (Fig. 4d). Transmission electron microscopy confirmed this, but revealed a material organization of the ridges more complex than that of the Morpho scales. At the ridge interior a highly electron dense medium exists, suggesting local deposition of melanin (Fig. 4e). Light microscopic observations as well as microspectrophotometry on blue scales immersed in refractive index matching fluid indeed revealed a substantial amount of melanin.
The melanin deposition in the center of the ridges will act as an optical isolation mechanism, which thus explains the restricted spatial spread of reflected light in the scatterogram (Fig. 4c). Below we will recognize a similar and even much stronger isolation mechanism in the green scales.
Complex photonics of the green scales
Transmission electron microscopy revealed that the upper lamina of the green scales is indeed organized in a unique way. The lamellae fully fill the space in between neighboring ridges and even touch each other, so creating an almost continuous multilayer. This organization strongly deviates from that of ordinary papilionid scales, which normally have irregular arranged cross-ribs (e.g., Fig. 2c, d). Usually the laterally extending lamellae of the ridges are narrow and skewed with respect to the scale surface and have only limited overlap (compare the cross-sections of the green cover scale with the underlying black ground scale in Fig. 5d and the blue cover scale of Fig. 4d). That the elaborate ridges of the green scales have an extra-ordinary regular organization is also clear from a cross-section observed with scanning electron microscopy (Fig. 5e).
Interestingly, the ridge centers of the green scales contain a highly electron-dense material (Fig. 5d), like the blue scales (Fig. 4e). The suggested presence of melanin was demonstrated by embedding a scale in immersion oil and observing it with a light microscope using transmitted light (Fig. 5f). This revealed dark, brown-black stripes with distance of 0.8 μm, fully corresponding with the ridge distance (Fig. 5c-e). Absorbance measurements unequivocally confirmed the local concentration of melanin in the ridge centers.
We furthermore investigated the diffraction pattern as a function of the angle of illumination and the polarization. To allow this, we inserted a linear polarizer and a pinhole into the secondary illumination beam of the imaging scatterometer, allowing illumination with polarized light from angles of incidence between 0° and 90°. Figure 7e, f shows the angle-dependency for TE- and TM-polarized light, respectively. As expected, when the angle of incidence increases, the diffraction pattern also shifts to larger angles. More importantly, the color of the 0th order reflection strongly varies with polarization and angle of incidence. Unexpectedly, the color change of the 0th order reflection deviates from the typical iridescence of a multilayer, i.e., a blue shift with increasing angle of incidence). Somewhat erratically, the reflection first shifts to the red (with a maximum in-between 40 and 50°) before shifting to the blue. The angle-dependency of the diffraction pattern, i.e., the 0th, 1st and -1st diffraction order, can be well understood as to be from a grating with a ridge distance of ~0.77 μm (shaded bands overlaid in Fig. 7e).
FDTD modelling of the photonic response
Normal illumination of an ideal chitin-air multilayer structure (Fig. 8a, i) causes a polarization-independent reflectance spectrum with a maximum of ~0.99 at 630 nm (i.e., peak wavelength λ max = 2 (d c n c + d a) with a chitin refractive index n c ≈ 1.55 ). Regular-spaced, orthogonal air slabs in the chitin-air multilayer (Fig. 8a, ii) invoke a minor form birefringence, but still a saturating reflectance at ~620 nm, with small oscillations in the reflectance spectrum (Fig. 8c). Putting melanin-containing baffles in the chitin-air multilayer (Fig. 8a, iii) has a severe optical effect, however, causing a pronounced polarization-dependency. The TE-reflectance spectrum shows a distinct peak in the green, at ~540 nm, with sidelobes at larger wavelengths, whereas the multi-lobed TM-reflectance spectrum peaks in the red, at ~720 nm (Fig. 8d). The multilayer with both the regular spaced air holes and the melanized baffles (Fig. 8a, iv) is a photonic structure as that found in the butterfly scales (Fig. 5). The spectra obtained by FDTD modelling (Fig. 8e) are indeed very similar to those measured experimentally (Fig. 6c). The TE-polarized reflectance is maximal in the green, at ~530 nm, with minor sidelobes in the yellow-red wavelength range, whereas the TM-polarized reflectance spectrum has multiple peaks with very similar reflectance values of ~0.3 at 520, 610 and 700 nm, respectively. The angle-dependent scattering calculated for this optical structure (Fig. 7g, h) corresponds closely to the experimentally observed scattering, showing strong grating-like diffraction (Fig. 7e, f).
The coloration toolkit of the male Rajah Brooke’s Birdwing, Trogonoptera brookiana, relies on a diversity of nanostructures, which, in combination with various absorbing pigments, create the strikingly vivid coloration of the butterfly. The optics of the pigmentary colored scales can be well understood as a basic combination of a thin film reflector and a strongly absorbing pigment. Papiliochrome pigment and multilayers determine the reflection properties of the red hairs; complex structured ridge multilayers and melanin-containing, absorbing baffles play a central role in the optics of the blue and green wing scales.
Thin film reflectors in black and white scales
It is commonly assumed that the color of pigmented butterfly wing scales is due to the scattering of light by the wing scale’s irregular structures and that the wavelength-dependent absorbing pigment determines the scale’s color, because it acts as a high-pass spectral filter on the scattered light. We found that the white and black wing scales of T. brookiana have widely open windows and irregular cross-ribs (Fig. 2c, d). The lower lamina, acting as a thin film reflector, determines the reflectance spectrum of the white scales. The peak reflectance is at ~450 nm, indicating a lower lamina thickness of ~200 nm (Fig. 2e). This falls well in line with recent observations across all major butterfly families of the presence of thin film reflectors in pigmented wing scales [4, 8, 10, 11, 13]. For instance, the blue eye spots in the wings of the Peacock butterfly, Inachis io (Nymphalidae), were found to be created by pigmentless cover scales overlapping black ground scales, where the cover scales’ lower lamina acts as a blue-reflecting thin film. On the other hand, wing areas of the Peacock and other nymphalines where both cover and ground scales are pigmentless have a distinctly white color as a result from cumulative reflections of cover and ground scales as well as the wing substrate. The reflectance spectra of Fig. 1c and Fig. 2f are very similar to those measured in the blue and white wing areas of the nymphalines as well as in another papilionid, Papilio xuthus . Yet, whereas the lower lamina of the blue scales of the nymphaline butterflies was a single, chitinous layer, the lower lamina of the bluish scales of P. xuthus was a multilayer consisting of two membranes with an air gap in between the membranes. In all cases, the scale’s reflectance spectrum, which depends on the thin film thickness (~150–250 nm), appears to be well-tuned to the absorbance spectrum of the scale’s pigment [4, 8, 10, 13, 26]. We note here that the anatomy of the black scales of T. brookiana is almost identical to that of the white scales, and their lower lamina also acts as a blue thin film reflector. However, a high concentration of melanin severely reduces the reflectance, thus causing the scales’ blackness.
Complex photonic structures in Trogonoptera: ordered Morpho-type photonic structures
The photonics of the blue and green wing scales is remarkably complex and seems to have uniquely evolved in the animal kingdom. Compared to the well-known Morpho butterflies, two main differences are obvious: the order of the ridges is extremely high, and baffles of melanin within the ridges affect the optical characteristics (Figs. 4 and 5). Morpho butterflies show extreme blue iridescence due to a disordered multilayer, with severe height and position disorder of the ridge layers [36–38], causing the iconic Christmas tree structure of transmission electron micrographs . Light diffraction by the ridges causes the line-like pattern in scatterograms .
What is the optical advantage of the extreme order in the green wing scales of Trogonoptera brookiana? First of all, the ordered ridges invoke form birefringence resulting in a strong polarization-dependent reflectance (Figs. 6, 7 and 8), which is much less in butterflies with similar, disordered architectures. Secondly, the order invokes a grating-like, spatially restricted reflection pattern, resulting in extreme color changes with minute changes in viewing angle (Fig. 6d, e). Similar optical effects have been noticed in other organisms, like birds-of-paradise, but the underlying structures have very different topologies [39, 40]. Thirdly, the presence of melanin in the ridges adds a novel optical mechanism that severely changes the spectral response and shapes the spatial reflections.
The rather extreme scale curvature of the green scales, with their very convex tip, spreads the light reflected by the grating structure into the hemisphere along the long axis of the scale (Fig. 7a-d). Scale curvature is not unusual in structured butterfly wing scales and is usually attributed to maximizing the viewing angle and/or shifting and spreading the viewing direction, as was demonstrated in some pierid or riodinid butterfly species having photonic structures similar to those encountered in Trogonoptera brookiana.
The coloration of Rajah Brooke’s birdwings appears to be developed in different ways. As noted above, each scale type is optimized for a specific signaling purpose using various photonic structures. The prominent tooth-shaped green markings that are contrasted by the jet-black wing borders will likely serve as a potential aposematic signal to predators, similar to other strongly colored markings of related papilionids [2, 7, 42–44]. Especially so, since larval stages of T. brookiana have poisonous Aristolochiaceae as their main foodplants . Furthermore, the Trogonoptera brookiana phenotype is unique amongst the birdwing butterflies and the striking pattern is probably associated to its unique communal behaviour where males often assemble in large groups .
Whether or not the wing scale colors are tuned by evolutionary selection for intraspecific recognition is a challenging question. Sexual dichromatism is present in birdwing butterflies where females generally possess a smaller number of color markings of smaller wing area compared to the males. In Trogonoptera brookiana the sexual dichromatism is far less distinctive than that of other sympatric birdwing species (e.g., Troides or Ornithoptera ). Female T. brookiana carry green wing patches on the dorsal wings, quite similar to the male, however in females these green areas are associated with an extensive white pattern. Furthermore, the discodial area of the hindwing is completely blue in the hindwing, but in the male these blue lines are restricted to the basal areas of the wing. When in motion, these different patterns will most likely emit quite a different signal.
Sexual dichromatism functions in mate recognition, enabled by a rich set of spectral photoreceptors . Most likely Troides and Trogonoptera, which are in the same tribe (Troidini) in the family of Papilionidae [1, 2], evolved quite similar sets of spectral receptors. For the Golden Birdwing butterfly, Troides aeacus formosanus, Chen et al. determined by intracellular recordings seven different photoreceptor types, with spectral sensitivities ranging from the UV to red. A comparison of the reflectance spectra of the colored wing areas in T. brookiana with the spectral sensitivities of the different photoreceptors indicates a stark spectral contrast of the various wing areas with the surrounding black framing of melanized scales (Fig. 1a, b). This indeed suggests that the wing colors are tuned to the butterfly’s visual system; similar to what has been previously observed in related butterflies .
Wing scale development
The degree of order in the green and blue scales, but also the multilayering of the red bristles, is quite remarkable. All butterfly wing scales are hypothesized to develop via a similar pathway by the (out-)folding of cell membranes and organelles (see Ghiradella’s seminal studies [9, 29, 48]) as well as by the preferential alignment of intracellular F-actin fiber networks . For the folding of multilayered ridges, Ghiradella’s observations of developing wing scales indicate that the multilayers are formed by elastic buckling of the cell membrane and subsequent backfilling with nascent cuticle [9, 29, 48]. Drying of this chitinous cuticle after cell apoptosis results in the final, highly anisotropic cell shape , as those observed in the SEM images of Figs. 2, 3, 4 and 5. The deposition of the melanin in the ridge centers will most likely happen subsequent to the buckling process. It will be of extreme interest to further investigate which cellular parameters control or drive the cellular processes on the nanoscale given the unusual degree of order observed in these wing scales, especially because the order must be the result of evolutionary selection.
Recently extensive nanotechnological attempts have been undertaken to mimic the photonic structures of butterfly scales in materials with novel optical effects and/or advanced functionalities. The exact fabrication of complex three-dimensional topologies is still beyond current nanofabrication capabilities, however [50–52]. The wing scales of T. brookiana have served as templates for creating light trapping structures based on the black wing scales via an inverse SiO2 replica [21, 23, 24]. Although improperly described at some points, the latter authors show that replication of the black scales results in black optical structures with similar morphology. The green wing scales could inspire the production of highly efficient gas sensors, due to the large surface area, similar to the sensors based on the well-structured, multilayered wing scales of Morpho butterflies [53–55].
In conclusion, the coloration mechanisms of Rajah Brooke’s Birdwing consist of thin films, multilayers and higher dimensional photonic structures that are extremely ordered at the nanoscale, resulting in the birdwing’s stunning coloration. We for the first time observed structural color in butterfly hairs and observed that the wing scales of the showy green patches provide yet another example of uniquely arranged structures that create reflection patterns with strong polarization contrast, thus expanding our insight into biophotonic coloration, especially in insects. The birdwings’ novel, nanoscale-controlled structure may well provide inspiration for biomimetic applications.
The investigated specimens of Rajah Brooke’s Birdwing, Trogonoptera brookiana albescens (Rothschild, 1895) (Lepidoptera: Papilionidae: Troidini), were obtained from Worldwide Butterflies (Dorset, UK; www.wwb.co.uk).
Reflectance spectra of the wings of intact butterflies were measured (in air) with a bifurcated fiber-optic probe. The probe comprised six light guides, delivering light from a halogen-deuterium source (AvaLight-D(H)-S-bal; Avantes, Eerbeek, the Netherlands), which surrounded a central fiber that acts as a light collector of reflected light (of a spot with diameter ~1 mm) and which delivered it to a fiber optic spectrometer (Maya2000Pro; Ocean Optics, Duiven, the Netherlands). A white diffusing reflectance standard (Ocean Optics WS-1) served as the reference.
Absorbance spectra of single wing scales immersed in refractive index matching fluid as well as polarization-dependent reflectance spectra of single scales were measured with a custom-built microspectrophotometer. The light beam of a xenon light source was coupled with a quartz lens into the microscope, equipped with an Olympus 20x/0.45 objective. The spectral range of the microspectrophotometer was limited to wavelengths ≥ 360 nm.
Scanning electron microscopy
The ultrastructure of the wing scales was investigated with a Tescan MIRA 3 LMH field-emission scanning electron microscope (Tescan, Brno, Czech Republic). To prevent charging, the samples were sputtered with a thin layer of palladium or gold prior to imaging.
Transmission electron microscopy
For transmission electron microscopy (TEM) of the scales, wing parts were prefixed in 2 % paraformaldehyde and 2.5 % glutaraldehyde in 0.1 mol l−1 sodium cacodylate buffer (CB, pH 7.3) for ∼ 45 min. After dehydrating with a graded series of ethanol and infiltration with propylene oxide, the tissues were embedded in Spurr's resin. The tissues were cut into 50 nm ultrathin sections, double-stained with uranyl acetate and lead citrated and observed using a Hitachi H7650 (Tokyo, Japan) transmission electron microscope (as outlined in ).
The hemispherical far-field light scattering pattern of single scales was visualized with an imaging scatterometer [14, 34, 56]. The scatterometer is built around an ellipsoidal mirror, which collects light from a full hemisphere around its first focal point, where the sample is positioned. Illumination was with a white light source (a xenon lamp), which delivered a narrow aperture (~5°) beam. For polarisation-dependent measurements, a linear sheet polarizer was added to the light path of the secondary beam. A small piece of magnesium oxide served as a white diffuse reference object. Images were acquired with an Olympus DP-70 camera and were subsequently corrected for geometrical distortions using a MATLAB routine.
Finite-difference time-domain simulations
The polarization-dependent light scattering of various models was simulated with three-dimensional finite-difference time-domain (FDTD) calculations. We used Lumerical FDTD Solutions 8.15, a commercial-grade Maxwell equation solver. Each model was placed in a three-dimensional simulation volume of 2x10x6 μm3. The light source covered a wavelength range of 350 to 800 nm. For the refractive index dispersion of melanin and chitin we used previously published data [25, 57].
We thank two reviewers for constructive comments, Dr. Nicholas Roberts for reading an early version of the manuscript and Hein L. Leertouwer for on-going support and technical assistance.
This research was partly supported through the National Centre of Competence in Research “Bio-Inspired Materials” and the Adolphe Merkle Foundation (to BDW) and the Air Force Office of Scientific Research/European Office of Aerospace Research and Development AFOSR/EOARD (grant FA9550-15-1-0068 to DGS).
All authors designed research, performed experiments and analyzed experiments. BDW and DGS wrote the paper. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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How Carbon 14 Dating Works HowStuffWorks
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L’Arctique et la couche d’Ozone
The Arctic region, around the North Pole, is an important indicator of the impacts of industrial and human activities, both at the surface level and in the atmosphere. The rapid warming of the region has attracted considerable scientific attention.
Besides the well known phenomenon of global warming occurring in our lower atmosphere, another atmospheric phenomenon had been taking place over the Arctic. Recent record low ozone values in the stratosphere have led scientists to take a closer look at the links between the changing climate and ozone distribution; changes that may undermine the recovery of the Ozone layer predicted to occur in a few decades.
This 18 minutes documentary was produced by the United Nations Environmental Program.
- Pour plus d’information sur les actions des Nations Unies sur la protection de la couche d’Ozone, c’est ici : http://www.unep.org/ozonaction/
Production: Check-in Films
Directed by : Thibault Dufour & Philip Drouin
Music: Louis de Saxcé
Animation: Marc Héricher
© Check-in Films / October 2013 | <urn:uuid:86c3e123-0c0b-46d0-9da8-1d1cf87243c2> | 3.046875 | 241 | Product Page | Science & Tech. | 29.910116 | 95,578,788 |
By: Audrey Tan
SINGAPORE – In land-scarce Singapore, the quest to harvest more energy from the sun will soon go one step further.
The Housing Board (HDB) – one of the agencies leading the nation’s efforts to ramp up solar energy use – is setting its sights on a novel area of research: the sea.
On Sunday (July 8), HDB announced that it will be signing a research collaboration with a landscaping firm in the coming week for the study and development of a floating solar system for coastal marine conditions.
The study, said HDB, would see how its floating system can withstand harsher environmental conditions in the sea, such as stronger winds and wave action.
HDB chief executive Cheong Koon Hean said that over the past decade, the agency has been spearheading solar initiatives and accelerating solar adoption in Singapore.
For example, solar panels have been installed or are being fitted in more than 2,400 HDB blocks across Singapore. By 2020, about 5,500 HDB blocks will be fitted with or identified for solar installation.
The energy generated by these panels usually go to common services such as lifts, water pumps and lighting for common areas.
More than 95 per cent of Singapore’s grid energy comes from the burning of natural gas.
Though natural gas is considered the cleanest form of fossil fuel, its combustion still contributes to the production of greenhouse gases.
Renewable energy from the sun, however, would reduce Singapore’s reliance on fossil fuels. Its use is also in line with the Republic’s target to reduce greenhouse gas emissions.
But considering Singapore’s small land area, there is a limit to how much renewable energy from the sun can be harvested from solar panels installed on land.
“One way to further harvest Singapore’s solar energy is to look beyond the sky to the sea. This is a practical approach, considering Singapore’s land constraints,” Dr Cheong said.
HDB’s floating modular system, first tested in 2011 at a man-made waterway in Punggol to hold wetland plants, was subsequently deployed to hold solar panels at a solar panel test bed in Tengeh Reservoir in Tuas in May this year.
The latest research agreement, which HDB will sign with ISO Landscape during the World Cities Summit, a sustainability conference this week, will look at how the HDB-designed floating modular system can hold solar panels in open sea conditions.
Said Dr Cheong: “HDB will further collaborate with industry partners to explore how best we can expand the use of our system in open sea conditions for solar deployment.”
Dr Thomas Reindl, deputy chief executive of the Solar Energy Research Institute of Singapore (Seris), said that Singapore has, in theory, a few areas where off-shore floating solar systems would be possible.
“The locations should have the right balance between the distance from the main island, to avoid lengthy submarine cable connections, and other marine uses, such as recreational activities, protected marine life areas or shipping routes,” he told The Straits Times, although he said it was too early to point out specific locations.
He added that other than wave action, greater currents and the corrosiveness of salt water, another important factor to consider during the study would be biofouling – the growth of marine organisms such as barnacles – on floats.
“Singapore has some of the richest waters and a vibrant marine life, hence the growth of barnacles and other marine life on the floats has to be considered during design and operation. Also, soiling from birds could be an issue, which has been observed in near-coastal floating solar installations such as the Singapore test bed and systems in the United Kingdom,” said Dr Reindl.
While HDB’s announcement represented Singapore’s first official foray into testing solar panels on the sea, there are other ongoing research projects studying the use of solar panels in inland water bodies such as reservoirs.
The Tengeh Reservoir test bed, for example, is being used to study the performance and cost-effectiveness of 10 different solar photovoltaic systems, including the one using HDB’s engineering system.
Separately, national water agency PUB is also doing studies on how solar panels can be added to four reservoirs here to power its energy-intensive water treatment processes.
Said Dr Reindl: “Off-shore floating photovoltaic (solar) systems have great potential for Singapore. Theoretically, there could be solar installations deployed on nearby waters and it could help to speed up the deployment of solar PV in the city state. Singapore could set a trend in that area and become one of the largest adopters of such innovative technology worldwide.” | <urn:uuid:b7974e83-5a75-4e16-8f2c-88f5e3fa7ea1> | 2.90625 | 1,003 | News Article | Science & Tech. | 36.490387 | 95,578,799 |
Show what electronic arrangements (electrons occupying sub shells of different ml and ms) that would lead to spectroscopic terms 6H, 5I and 8S, and identify one element each that have these terms as (see attached) the lowest energy spectroscopic terms.
See attached for full formatting.© BrainMass Inc. brainmass.com July 17, 2018, 9:22 pm ad1c9bdddf
I doubt it is first year spectroscopy problem. It is a much higher level of spectroscopy. Anyhow looking into your background I will try to explain your question in as simple manner as possible so that you may not get confused.
Magnetic quantum number ml designates the orientation of electronic orbitals. So if we have five d electrons ,one each in five d orbitals we will have l values as -2,-1,0,+1,+2 and a total L value equal to (-2)+(-1)+(0)+(+1)+(+2) = 0. Acording to ...
363 words explaining the concepts behind electronic arrangements and the spectroscopic terms they lead to. | <urn:uuid:6d4e3ea9-da1d-4333-8979-cf6fea7d90f4> | 3.53125 | 235 | Q&A Forum | Science & Tech. | 69.203746 | 95,578,801 |
From Event: SPIE Optical Engineering + Applications, 2017
NASA’s Sustainable Land Imaging (SLI) program, managed through the Earth Science Technology Office, aims to develop technologies that will provide future Landsat-like measurements. SLI aims to develop a new generation of smaller, more capable, less costly payloads that meet or exceed current imaging capabilities. One projects funded by this program is Ball’s Compact Hyperspectral Prism Spectrometer (CHPS), a visible-to-shortwave imaging spectrometer that provides legacy Landsat data products as well as hyperspectral coverage suitable for a broad range of land science products. CHPS exhibits extremely low straylight and accommodates full aperture, full optical path calibration needed to ensure the high radiometric accuracy demanded by SLI measurement objectives. Low polarization sensitivity in visible to near-infrared bands facilitates coastal water science as first demonstrated by the exceptional performance of the Operational Land Imager. Our goal is to mature CHPS imaging spectrometer technology for infusion into the SLI program. Our effort builds on technology development initiated by Ball IRAD investment and includes laboratory and airborne demonstration, data distribution to science collaborators, and maturation of technology for spaceborne demonstration. CHPS is a three year program with expected exiting technology readiness of TRL-6. The 2013 NRC report Landsat and Beyond: Sustaining and Enhancing the Nations Land Imaging Program recommended that the nation should “maintain a sustained, space-based, land-imaging program, while ensuring the continuity of 42-years of multispectral information.” We are confident that CHPS provides a path to achieve this goal while enabling new science measurements and significantly reducing the cost, size, and volume of the VSWIR instrument.
Thomas U. Kampe and William S. Good, "Pathway to future sustainable land imaging: the compact hyperspectral prism spectrometer," Proc. SPIE 10402, Earth Observing Systems XXII, 1040208 (Presented at SPIE Optical Engineering + Applications: August 06, 2017; Published: 5 September 2017); https://doi.org/10.1117/12.2270932.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations. | <urn:uuid:603593c5-7de7-4e64-8ffc-2f47df234e9f> | 2.734375 | 521 | Academic Writing | Science & Tech. | 20.535349 | 95,578,829 |
are used to take measurements in standardized ways and to control error and
precision. Mathematical techniques are used to recognize relationships among the
variables measured and to develop formulas and generalizations based on that
Using a collection of
three circular objects, rulers with inches and centimeters, and some string,
derive a relationship between the diameter of a circle and its
After completing the
given problem, write an essay (suggested length of 3-5 pages) in which
you do the following:
A. Describe your
problem-solving process, including the following:
1. Describe the measurement tools used.
2. Describe the data collection process. (Make sure to take
measurements in both metric and traditional units.)
3. Explain how measurements are approximations.
4. Provide a table of the data collected for all three
of the items measured.
5. Explain how differences in units affect precision.
B. Explain how to use the collected data to derive an experimental
value for pi (i.e., a relationship between the diameter of a circle and its
C. Analyze the degree of error in your measurements and your
experimental value of pi, using the known value of pi.
D. If you use sources, include all in-text citations and© BrainMass Inc. brainmass.com July 16, 2018, 1:07 am ad1c9bdddf
1) Describe how elastic the string is. A more elastic string (such as yarn) will give less accurate answers. Describe how accurate the ruler is. Is the ruler in inches or centimeters? All commercially-made rulers are subject to inaccuracies due to manufacturing and weather. Metal rulers are prone to expanding or contracting due to heat or cold. For more accurate results, make sure your ruler is long enough to measure the string without resorting to folding the string or measuring the string in multiple parts.
Describe the circular objects. They might not be perfectly circular, as it is very difficult to make an object that is perfect. Are they spherical objects or cylindrical objects? Include at least one spherical and one cylindrical object so that you can explain the difficulties with measuring each (I have explained some of this in #3 below). Are the objects stiff enough to be measured? If you are measuring a basketball, is it filled with enough air so that it is as close to being spherical as is possible? Is the object smooth? Perhaps it has bumps on it, like a basketball does. That will affect the measurement. The size of the object also affects the accuracy of the measurement. It is harder to measure a tiny object than it is to measure a large object.
2) When collecting data, make sure ...
Procedure for measuring objects to approximate pi and problems with approximations. | <urn:uuid:dab8552b-e7ee-472c-882c-ff586bc9616f> | 3.859375 | 586 | Tutorial | Science & Tech. | 48.820907 | 95,578,880 |
THE iceberg that recently calved off a Greenland glacier and spectacularly parked itself outside the tiny village of Innaarsuit has caused the usual mainstream media heads to explode with man-made
global warming climate change, again, lazily fingered as the culprit in order to facilitate the CAGW brainwashing process…
“Extreme iceberg break-ups risk becoming more frequent because of climate change, some experts have warned.”
THE Innaarsuit Iceberg (Greenland)
THE fact that the iceberg has settled itself outside the tiny village of Innaarsuit may be of definite concern, if it decides to flip causing a tidal surge. But, to blame global warming, while not surprising from the fake news media, is dishonest to the phenomenon of glacier calving – a natural and dynamic process that’s been happening for eons.
Many glaciers terminate at oceans or freshwater lakes which results naturally with the calving of large numbers of icebergs. Calving of Greenland‘s glaciers produce 12,000 to 15,000 icebergs each year alone.
CUDOS to Ella Gilbert from the British Antarctic Survey who is often asked why icebergs break away…
“It’s complicated,” she explains. “The region is clearly undergoing a lot of change but you can’t just say ‘it was the climate’. Iceberg calving is a natural process anyway. If you put more snow in at one end, it has to come out the other end as icebergs.”
THE glacier-calving process more likely reflecting the very health of a glacier.
CERTAINLY true for Greenland, from where this particular iceberg originated, where over the past 19 months more than one trillion tons of new ice has formed on the giant ice-continent’s surface.
DUE to a lot more new snow accumulating each year during the long winter, than is melting during the short summer, the surface is rapidly gaining ice, and glaciers are growing.
HOWEVER, scientists and the press (of course) report the exact opposite…
(“Global Sea-Levels” check : TOP 10 Climate Change Alarmist Myths Unearthed : #2 SEA LEVEL RISE | Climatism)
YOU can easily spot the the NYTimes‘ fake-news and brazen climate lies by checking actual government ‘data’…
GREENLAND ICE-DATA (DMI)
ESSENTIAL reading and research for the ‘failing’ Guardian and New York Times respectively, who both launched new attack pieces on essential trace gas CO2, claiming this time that “Climate change [CO2] will make rice less nutritious”… 🤔
Before it was expropriated by the global warming/climate change movement, the term “Greenhouse Effect” referred to the effect of elevated carbon dioxide in greenhouses on crop chemistry. We know from greenhouse studies going back to the late 19th century that crop chemistry reflects the balance between soil chemistry, air chemistry, and light intensity. The important features of air chemistry are the availability of carbon dioxide for photosynthesis and of oxygen for plant respiration. The important features of soil chemistry are the availability of water, nitrates, phosphates, and minerals.
Greenhouse operations irrigation, air circulation to maintain air quality, heating for temperature control, the introduction of carbon dioxide to maintain elevated carbon dioxide levels of 1000 to 2000 parts per million for photosynthesis enrichment, and the availability of sufficient light for photosynthesis to occur. Photosynthesis enrichment improves crop yield and corresponding changes to soil chemistry must also be maintained to preserve the…
View original post 295 more words
CLIMATE change alarmists conveniently ‘deny’ the existence of the 1970’s “global cooling” scare because such panic, a mere 40 years ago, threatens the legitimacy of the current “global warming” scare.
HOWEVER, climate experts and government agencies of the day were indeed warning of impending climate doom and that we must take immediate “action” to avoid catastrophe.
WARMING alarmists rebut the 1970’s global cooling scare with claims that the phenomenon wasn’t “peer-reviewed” or that a “consensus” of “97%” of “scientists” didn’t agree. However, it doesn’t take Einstein to realise that the fashionable eco-scare of the day was indeed very real…
IN 1976 the CIA warned the cooling climate would bring – “drought, starvation, social unrest and political upheaval” :
C.I.A. WARNINGFrom a correspondent in Washington
MAJOR world climate changes were under way that would cause economic and political upheavals “almost beyond comprehension”, an internal report of the Central Intelligence Agency has warned the US Government.
“The new climatic era brings a promise of famine and starvation to many areas of the world”, the report warns.
The report, which contends that the Climate changes began in 1960, is based on a study by Mr Reid Bryson of the University of Wisconsin.
Its basic premise is that the world’s climate is cooling and will revert to conditions prevalent between 1600 and 1850 — when the earth’s population was less than 1,000 million and its rural, pre-industrial era civilisations were largely capable of feeding themselves.
The report, which- was concerned with possible political and economic threats the United States could expect from such drastic events, said the starvation and famine would lead to social unrest and global migration of populations.
Superbly written Donna.
ERICA Goode’s unhinged attack on Dr. Crockford in the NY Times is further evidence of the totalitarian and authoritarian underpinnings that have corrupted the field of climate ‘science’. – Question the preferred wisdom of the day at your own peril! – Obey, or be persecuted and have your reputation trashed! This isn’t science, this is religion. “Belief” and “Denial” are the words of zealots, not scientists.
WHAT would it take for activists Goode and Co. to be happy? A Polar Bear population back to 1960’s extinction levels? Sadly, I believe the answer is yes! How dare their scared ‘cow’ and mascot of climate catastrophe have grown in population from some 5,000 in the 1960’s to 25,000-30,000 at present, despite rising CO2 and diminished sea-ice extent?
INCREASING polar bear numbers, directly threaten the power of activists and their lucrative climate change scare. We can’t have that now can we Erica?
SPOTLIGHT: Journalistic professionalism evaporates in front of our eyes.
BIG PICTURE: When historians document the demise of the mainstream media, an article published this week by the New York Times will make an excellent case study. Titled “Climate Change Denialists Say Polar Bears Are Fine. Scientists Are Pushing Back,” it’s written by Erica Goode who isn’t just any journalist. She’s a former Environment Editor of the Times. In 2009, she “founded and led a cluster of reporters dedicated to environmental reporting.” Currently, she’s a visiting professor at Syracuse University.
Out here in the real world, a debate exists about polar bears. Will they be adversely affected by climate change or will they continue to adapt as they have historically?
Since the future hasn’t yet arrived, it’s impossible to know whose opinions will turn out to be correct. But rather than presenting a range of perspectives…
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“The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary.” – H. L. Mencken
DEPICTIONS of catastrophic sea-level rise have become a useful propaganda tool for useful idiots in the Climate Crisis Industry who invent the most absurd future sea-level rise scenarios and recreate them in photoshopped horror stories that aim to shock you into belief…
THE only place where such catastrophic scenarios exist are in the warped minds of alarmist hysterics who occupy the climate controlled offices of NASA, NOAA, BoM, National Geographic and the New York Times et al. Not even worst case scenario UN IPCC RCP8.5 climate models project such doom.
IN 2000, climate expert Dr David Viner of the University of East Anglia’s Climate Research Unit (CRU) assured us that…
AT the beginning of the Century we were told by Dr David Viner – fmr senior
activist scientist at the UEA’s climatic research unit (CRU) – that Snowfall would become “a very rare and exciting event,” and that “Children just aren’t going to know what snow is.”
SINCE Viner’s epic fail in 2000, the global temperature dial has been stubbornly stuck on Pause, with some of the ‘snowiest’ and coldest winters on record occurring over the same period, despite record and rising CO2 emissions…
2018 has been no exception with extreme cold and record snowfalls affecting vast areas of the Northern Hemisphere with rare snow touching down in areas as far south as Southern Morocco, and the Sahara desert. We’ve even seen sharks frozen to death on the shores of Cape Cod, and Iguanas frozen solid in Florida!
ALL this happening in the years that climate
activists scientists tell us are the “Hottest Evah“.
IT would appear Mother Nature is speaking a different language to that of her warmist subjects living life inside the bubble of man-made global warming hysteria!
“BEAST FROM THE EAST”
UK is currently under siege from an epic Siberian cold front dubbed the “Beast from the east”…
ANTICIPATING the negative impact the “beast from the east” might have on the global warming narrative, the mainstream media has gone into full propaganda mode churning out numerous reports dismissing the sub-zero extremes on…you guessed it, “global warming”!
THIS actual headline from The Guardian’s resident climate catastrophist, George Monbiot, particularly mind-blowing…
IN the post-modern era of climate ‘science’ COLD = HOT…
THE counter-claim by climate
activists scientists like Vladimir Petoukhov of the Potsdam Institute is that shrinking Arctic sea ice “could triple the probability of cold winter extremes in Europe and northern Asia”. The well-orchestrated claim jumped on and circulated by the activist press…
THIS is all a rehash of the junk science originally promoted by Jennifer Francis in 2014
THE other Hot-off-the-press weather event circulated by the media, in order to divert attention away from the brutal cold, has been the apparent “unprecedented” warmth in the Arctic. A claim expertly debunked by Paul Homewood in this must read post: Arctic Alarmists Hit New Records Of Hysteria | NOT A LOT OF PEOPLE KNOW THAT
MEANWHILE, as the climate mafia propagandisers inside their COLD = HOT bubble, the other conveniently forgotten pole, Antarctica, continues its long 40 year+ cooling trend, gaining ice mass despite record and rising CO2 levels and claims of “The Hottest Years Evah“…
From the abstract:
Mass changes of the Antarctic ice sheet impact sea-level rise as climate changes, but recent rates have been uncertain. Ice, Cloud and land Elevation Satellite (ICESat) data (2003–08) show mass gains from snow accumulation exceeded discharge losses by 82 ± 25 Gt a−1, reducing global sea-level rise by 0.23 mm a−1.
DON’T MENTION “THE SUN”!
Roger Tallbloke with a final word that makes a lot more sense than the pseudoscientific, HOT = COLD, bubble-world of
global warming climate change activists…
The role of the lowest solar cycle for at least a century is mostly ignored by believers in man-made global warming. There are signs of climate change, but not necessarily the kind they expect.
- LIVING Life With “Atmosphere Cancer” | Climatism
- The “HOTTEST YEAR EVAH” Meme Exposed | Climatism
- “HOTTEST YEAR EVAH” Claims Tell Us More About Global Warming PR Than Actual Science | Climatism
- SNOWFALL Will Become “A Very Rare And Exciting Event…” | Climatism
- “Children Just Won’t Know What An Honest Scientist Is” | The Deplorable Climate Science Blog
- It’s Called Weather, George!! | NOT A LOT OF PEOPLE KNOW THAT
- 20 New Papers Crush Claims Of A Man-Made Link To Arctic Climate Change, Glacier Retreat, Sea Ice | Climatism
- STATE of the Polar Bear Report 2017 shows Polar Bears are thriving | Climatism
Climatism hot links :
- CLIMATE CHANGE – The Most Massive Scientific Fraud In Human History | Climatism
- WESTERN Nations, Driven By A Global Agenda Of Climate Alarmism, Are Destroying Their Industries With Carbon Taxes And Promotion Of Expensive, Intermittent Green Energy | Climatism
- THE Greatest Threat To The Environment Is Not Affluence, It’s Poverty | Climatism
Climate Science related :
- 100% Of Climate Models Prove that 97% of Climate Scientists Were Wrong! | Climatism
- THE Great Global Warming “Pause” | Climatism
- THE Climate Change Farce Explained By Two Expert “Scientists” | Climatism
- WORLD Leading Authority : Climate and Sea Level Science Is A “Quasi Religion” Hijacked By An Activist Agenda | Climatism
- THE “97% Consensus” Meme Further Discredited By 97 New Papers Supporting A Skeptical Position On Climate Alarm | Climatism
(Still waiting for that “big oil” cheque to arrive in the mail!)
Click this link for brief info…TQ, Jamie 🙂 | <urn:uuid:c9cf2676-dd19-4c87-a253-23d15c125e15> | 2.53125 | 3,032 | Comment Section | Science & Tech. | 32.795227 | 95,578,881 |
Modern robots are truly amazing. Some, like Boston Dynamic's WildCat robot, can run faster than the fastest human on earth. Others, like Blue Frog Robotic's Buddy robot, are designed to be in-home companions that keep us company and help with daily tasks. Now, a new robot, dubbed Envirobot by its creators, has been engineered specifically to sniff out sources of water pollution.
Envirobot was designed by engineers at l’École polytechnique fédérale de Lausanne (EPFL) in Switzerland, the country's top Technology Institute, which boasts around 10,000 students and 300 professors. According to TechCrunch, these are the same engineers and robotics experts who helped bring Pleurobot (a semi-aquatic, salamander-like robot with highly realistic movements) to life. They also produced several realistic reptile robots for a BBC nature documentary--so convincingly lifelike that identifying them as robots takes a few second looks. Over the past several years, EPFL has made a worldwide name for itself by creating robots inspired by nature that can help solve problems created by people.
Envirobot is a perfect example. This eel-like robot was designed to swim, with uncannily lifelike movements. Measuring around four feet long, Envirobot's body is segmented, with each segment containing specific sensors designed to locate a particular type of water pollution. Envirobot can sense electrical, chemical and environmental disturbances in water, according to TechCrunch. Some of its body segments even contain sensors made from living organisms, according to Motherboard.
For example, one segment is filled with lab-bred, bio-luminescent bacteria which light up when they come into contact with mercury. Another segment of Envirobot contains a tiny science experiment in and of itself, in the form of two groups of near-microscopic planktonic crustaceans. One group is sealed in a compartment of clean water, while the other is exposed to the waters through which Envirobot swims. Once Envirobot makes its way back to shore, researchers can use a microscope to compare the behavior of the two crustacean groups. Unusual behavior, such as sluggishness, could be a sign of water pollution which Envirobot's other segments failed to find. Or they could serve as further confirmation of chemical or electrical disturbances picked up by other sensors.
The segments of Envirobot's body are also what enable it to swim with such lifelike precision. By pushing and pulling against one another, they allow Envirobot to "slither" through the water, like a snake or an eel. Though human's are required to place Envirobot in a body of water, the robot can pretty much take over from there, swimming on its own for as long as it is allowed, or until its battery runs out. Envirobot can be pre-programmed to swim in a specific pattern, controlled via remote, or allowed to swim autonomously.
It is this ease of movement and ability to record information from afar that makes Envirobot's creators so eager to use robots to help solve environmental problems. Auke Ijspeert, head of the Biorobotics Laboratory at EPFL, said in a news release that "there are many advantages to using swimming robots. They can take measurements and send us data in real time — much faster than if we had measurement stations set up around the lake. And compared with conventional propeller-driven underwater robots, they are less likely to get stuck in algae or branches as they move around. What’s more, they produce less of a wake, so they don’t disperse pollutants as much."
As of July 2017, Envirobot is still considered a prototype. It is currently being tested in the waters of Lake Geneva, and its creators hope to deploy it elsewhere for further testing as soon as possible.
Researchers from marine life advocates Oceana have discovered a surprising new world under the sea near Sicily.
Sweden's aggressive target of generating over 40 terawatt-hours of renewable energy by 2030 could be reached nearly a decade early. A massive amount of wind power projects could hit a snag in market value with subsidies, but SWEA could push to close those up by the end of the year.
Starbucks is ramping up its sustainability efforts with a plan to eradicate the use of plastic straws in its assembly line. | <urn:uuid:da738785-234e-44d9-86e0-c158984df147> | 3.515625 | 934 | News Article | Science & Tech. | 35.020304 | 95,578,884 |
Functionally linking microbial community structure with environmental chemistry
Arid lands, which cover some 40 percent of the Earth's terrestrial surface, are too dry to sustain much in the way of vegetation. But far from being barren, they are home to diverse communities of microorganisms--including fungi, bacteria, and archaea--that dwell together within the uppermost millimeters of soil. These biological soil crusts, or biocrusts, can exist for extended periods in a desiccated, dormant state. When it does rain, the microbes become metabolically active, setting in motion a cascade of activity that dramatically alters both the community structure and the soil chemistry.
"These biocrusts and other soil microbiomes contain a tremendous diversity of both microbes and small molecules ('metabolites'). However, the connection between the chemical diversity of soil and microbial diversity is poorly understood," said Trent Northen, a senior scientist at Lawrence Berkeley National Laboratory (Berkeley Lab).
In a paper published January 2, 2018, in Nature Communications, Berkeley Lab researchers led by the Northen lab report that specific compounds are transformed by and strongly associated with specific bacteria in native biological soil crust (biocrust) using a suite of tools Northen calls "exometabolomics." Understanding how microbial communities in the biocrusts adapt to their harsh environments could provide important clues to help shed light on the roles of soil microbes in the global carbon cycle.
The work follows a 2015 study that examined how specific small molecule compounds called "metabolites" were transformed in a mixture of bacterial isolates from biocrust samples cultured in a milieu of metabolites from the same soil. "We found that the microbes we investigated were 'picky' eaters," Northen said. "We thought we could use this information to link what's being consumed to the abundance of the microbes in the intact community, thereby linking the biology to the chemistry."
In the new study, the investigators set out to determine whether the microbe-metabolite relationships observed in the simplified test-tube system could be reproduced in a more complex soil environment. Biocrusts from the same source - representing four successive stages of maturation - were wet, and the soil water was sampled at five time points. The samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to characterize the metabolite composition ("metabolomics"), and biocrust DNA was extracted for shotgun sequencing to measure single copy gene markers for the dominant microbe species ("metagenomics").
"When we compare the patterns of metabolite uptake and production for isolated bacteria that are related to the most abundant microbes found in the biocrusts, we find that, excitingly, these patterns are maintained," said Northen. That is, increased abundance of a given microbe is negatively correlated with the metabolites that they consume and positively correlated with metabolites that they release.
When active, biocrusts take up atmospheric carbon dioxide and fix nitrogen, contributing to the ecosystem's primary productivity. They also process organic matter in soil, modifying key properties related to soil fertility and water availability.
"This study suggests that laboratory studies of microbial metabolite processing can help understand the role of these microbes in carbon cycling in the environment. This study gets us closer to understanding the complex food webs that are vital in nutrient dynamics and overall soil fertility," said study first author Tami Swenson, a scientific engineering associate in Northen's group within the Berkeley Lab Biosciences Area's Environmental Genomics and Systems Biology (EGSB) Division.
Northen's group is currently working on expanding these studies to capture a greater fraction of microbial diversity. Ultimately, this may enable the prediction of nutrient cycling in terrestrial microbial ecosystems, and perhaps even manipulation by adding specific metabolites.
The following Berkeley Lab researchers also contributed to the study: Benjamin Bowen, a member of Northen's lab in EGSB and at the Joint Genome Institute, a DOE Office of Science User Facility, helped analyze metabolomics data; Ulas Karaoz in the Earth and Environmental Sciences Area (EESA) analyzed metagenomics data; and Joel Swenson, a former postdoctoral researcher in Biosciences' Biological Systems and Engineering Division, helped conduct correlation and statistical analyses.
This work was supported under a DOE Office of Science Early Career Research Program award. DNA was sequenced using the Vincent J. Coates Genomics Sequencing Laboratory at UC Berkeley, supported by a National Institutes of Health Instrumentation Grant.
Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel Prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.
Dan Krotz | EurekAlert!
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
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13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences | <urn:uuid:67702f98-262c-4afe-948e-f01fb67e2495> | 3.46875 | 1,709 | Content Listing | Science & Tech. | 26.864276 | 95,578,885 |
The genus Metacyclops Kiefer in Australia (Crustacea: Copepoda: Cyclopoida), with description of two new speciesWA Museum Records and Supplements | Updated 1 years agoABSTRACT – Two new species of the genus Metacyclops Kiefer, 1927 are described from subterranean waters of Western Australia, one from the Kimberley region and the other from the Pilbara region. They both belong to the "trispinosus"-group, which has a clear Eastern Gondwana connection and the centre of diversity in Australia. A phyletic tree of this group in Australia is proposed. Metacyclops kimberleyi sp. nov. is distinguished from other members of the group by at least two autapomorphies: the exceptionally long dorsal seta on the caudal rami and the maxilliped with only seven armature elements. The only clear autapomorphy of M. pilbaricus sp. nov. seems to be its unusual body shape. An antenna without exopod and the second endopodal segment of this appendage with only six setae is a synapomorphy that suggests a close relationship between these two new species. As the genus Metacyclops in Australia already has seven valid species, a key to aid in their identification, as well as a map of their distributions, are presented. Author(s) T. Karanovic Volume Records 22 : Part 3 Article Published 2004 Page Number 193 DOI 10.18195/issn.0312-3162.22(3).2004.193-212 The genus Metacyclops Kiefer in Australia (Crustacea: Copepoda: Cyclopoida), with description of two new species Download 5.15 MB To request an accessible version of this pdf please email firstname.lastname@example.org View the discussion thread. | <urn:uuid:38e51e46-ebe1-436f-9e49-0d29601b26e0> | 2.546875 | 398 | Academic Writing | Science & Tech. | 47.697678 | 95,578,891 |
The last fish you ate probably came from the Bering Sea.
But during this century, the sea’s rich food web—stretching from Alaska to Russia—could fray as algae adapt to greenhouse conditions.
“All the fish that ends up in McDonald’s, fish sandwiches—that’s all Bering Sea fish,” said USC marine ecologist Dave Hutchins, whose former student at the University of Delaware, Clinton Hare, led research published Dec. 20 in Marine Ecology Progress Series, a leading journal in the field.
At present, the Bering Sea provides roughly half the fish caught in U.S. waters each year and nearly a third caught worldwide.
“The experiments we did up there definitely suggest that the changing ecosystem may support less of what we’re harvesting—things like pollock and hake,” Hutchins said.
While the study must be interpreted cautiously, its implications are harrowing, Hutchins said, especially since the Bering Sea is already warming.
“It's kind of a canary in a coal mine because it appears to be showing climate change effects before the rest of the ocean,” he noted.
“It’s warmer, marine mammals and birds are having massive die-offs, there are invasive species—in general, it’s changing to a more temperate ecosystem that’s not going to be as productive.”
Carbon dioxide’s direct effects on the ocean are often overlooked by the public.
“It’s all a good start that people get worried about melting ice and rising sea levels,” he said. “But we're now driving a comprehensive change in the way Earth's ecosystem works—and some of these changes don't bode well for its future.”
The study examined how climate change affects algal communities of phytoplankton, the heart of marine food webs.
Phytoplankton use sunlight to convert carbon dioxide into carbon-based food. As small fish eat the plankton and bigger fish eat the smaller fish, an entire ecosystem develops.
The Bering Sea is highly productive thanks mainly to diatoms, a large type of phytoplankton.
“Because they're large, diatoms are eaten by large zooplankton, which are then eaten by large fish,” Hutchins explained.
The scientists found that greenhouse conditions favored smaller types of phytoplankton over diatoms. Such a shift would ripple up the food chain: as diatoms become scarce, animals that eat diatoms would become scarce, and so forth.
“The food chain seems to be changing in a way that is not supporting these top predators, of which, of course, we’re the biggest,” Hutchins said.
A shift away from diatoms towards smaller phytoplankton could also undermine a key climate regulator called the “biological pump.”
When diatoms die, their heavier carbon-based remains sink to the seafloor. This creates a “pump” whereby diatoms transport carbon from the atmosphere into deep-sea storage, where it remains for at least 1,000 years.
“While smaller species often fix more carbon, they end up re-releasing CO2 in the surface ocean rather than storing it for long periods as the diatom-based community can do,” Hutchins explained.
This scenario could make the ocean less able to soak up atmospheric carbon dioxide.
“Right now, the ocean biology is sort of on our side,” Hutchins said. “About 50 percent of fossil fuel emissions since the industrial revolution is in the ocean, so if we didn’t have the ocean, atmospheric CO2 would be roughly twice what it is now.”
Hutchins and colleagues are doing related experiments in the north Atlantic Ocean and the Ross Sea, near Antarctica. The basic dynamics of a greenhouse ocean are not well understood, he noted.
“We’re trying to make a contribution by doing predictive experimental research that will help us understand where we’re headed,” he said. “It’s unprecedented the rate at which things are shifting around.”
The researchers collected the algae samples from the Bering Sea’s central basin and the southeastern continental shelf. They incubated the phytoplankton onboard, simulating sea surface temperatures and carbon dioxide concentrations predicted for 2100.
Each of these variables was tested together and independently. Ratios of diatom to nanophytoplankton in manipulated samples were then compared with those in plankton grown under present conditions.
The scientists found that photosynthesis in greenhouse samples sped up two to three times current rates. However, community composition shifted from diatoms to the smaller nanophytoplankton.
Temperature was the key driver of the shift with secondary impacts from the increased carbon dioxide concentrations, according to the study.
Terah DeJong | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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31st Parabolic Flight Campaign
- Title 31st Parabolic Flight Campaign
- Released: 24/02/2011
- Length 00:18:02
- Language English
- Footage Type Index
- Copyright ESA
Every year a group of European scientist get the chance to experience weightlessness in an initiative from ESA. They are able to conduct their experiment as they go up ina special plane that can create the same conditions as in space.
In parabolic flight, the aircraft is put into a specially-shaped trajectory that provides free-fall, or weightlessness. This weightless experience, other than the duration, is exactly that experienced by astronauts on orbital missions. Each flight begins by having theaircraft perform an aerobatic manoeuvre, which starts from level flight, and pitches up to apporximately 45 degrees nose-hight and wingls level subjecting the passengers to a 2 g pull up lasting about ten seconds. After that, the aircraft engines are powered back and the airplane is launched into the same parabolic trajectory that a ball would follow, providing everyone inside the plane with around twenty-five to thirty seconds of total weightlessness for experimentation puroposes. At the bottom of the parabol
00:00:38 Slate: 31st Parabolic Flight Campaign
00:00:57 Plane Liftoff
00:02:42 PHYSICAL SCIENCE EXPERIEMENTS
00:03:03 Liquid diffusion model experiment in low gravity (Dr G. Mathiak, Dr R, Willnecker, (DLR Koln) Dr A. Griesche, Prof G. Frohberg (TU Berlin))
00:04:25 Linear Diffusion flames representative of fires in microgravity environments (Prof P. Joulain, CHRS Poitiers, France)
00:06:03:08 Preliminary tests for the International MIcrogravity Plasma Facility (Prof G. MOfgill, Dr H. Thomas, Dr U. Konopka, (Max Plank INsititute, Garcheng, Germany))
00:07:32n Test of ICAPS facility for International space Station (Prof Blum (University of Jena, Germany))
00:08:56 Aerosol particle motion in temperature and concentration gradient (Prof J C. Legros, D A. Vedernikov (universite libre de Bruxelles, Belgium))
00:10:15 LIFE SCIENCE EXPERIMENTS
00:10:39 Dynamics of prehension in microgravity and its application to robotics and prosthetics (Prof J L. Thonnard, Dr O. White (universite ca
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Alien solar systems that are home to so-called "hot Jupiters" — gas giants circling sizzlingly close to their stars — are unlikely homes for Earth-like planets, researchers say.
Hot Jupiters get their name from the fact that they are approximately Jupiter's size, but extraordinarily near their stars, at about a tenth of the distance from Mercury to our sun. These roaster planets are among the alien worlds that astronomers have discovered most often since their size and proximity to their parent stars mean they exert large gravitational tugs on their hosts that scientists can readily spot.
This planet-finding technique, known as the "wobble method," detects the presence of giant planet near a star by the wobble motion induced on the star by the planet's gravity. The closer and larger the alien planet is, the more pronounced the wobble.
To explain how hot Jupiters form, researchers have developed two broad classes of explanations — one that also predicts the presence of nearby companion planets, and one that does not. Astronomers recently detected more than 2,000 candidate alien worlds with NASA's Kepler spacecraft, and by looking at whether hot Jupiters were found together with other types of planets, they can begin to pin down which theory of hot Jupiter formation is correct.
Astronomers looked at 63 hot Jupiter candidates. They found no compelling signs of planets elsewhere in their systems. [Gallery: Alien Planets Discovered by Kepler]
"A sample of 63 is an order of magnitude larger than all of the previous studies combined, making the results pretty definitive," study lead author Jason Steffen, an astrophysicist at the Fermilab Center for Particle Astrophysics in Batavia, Ill., told SPACE.com. "It should give people who model planet formation a good piece of information to work with."
The researchers also investigated other planet types. These included 31 "warm Jupiters," gas giants orbiting a bit farther away from their stars, as well as smaller worlds, including 52 "hot Earths" and 222 "hot Neptunes." These may often be found in multi-planet systems.
Models that suggest hot Jupiters are loners propose that these giants initially had highly elliptical orbits that eventually shrunk over time into tight, circular paths. As they migrate inward, their gravitational pull would likely scatter other planets away from their systems, which would explain the apparent solitude of hot Jupiters.
Still, Steffen warned that it may be possible that their results could miss very small planets that lie in the same systems as hot Jupiters, or planets in distant orbits.
The scientists detailed their findings online May 7 in the journal Proceedings of the National Academy of Sciences.
Copyright 2012 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
- Gravity Assist Podcast: Exploring Mars, with Steve Squyres
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- Scientists Prove Einstein Right Using the Most Elusive Particles in the Universe
- How Engineers Are Practicing for the BepiColombo Mission to Mercury (Video)
This article originally published at Space.com here | <urn:uuid:54f910fb-92ce-4d68-ad7b-475fe2b0e34c> | 3.484375 | 671 | Truncated | Science & Tech. | 36.407013 | 95,578,912 |
posted by Joey
Find csc(theta), tan (theta), and cos (theta), where theta is the angle shown in the figure.
Give exact values, not decimal approximations
the right angle is locate between sides a and b and the theta angle is an acutle angle sides b and c.
i have sin theta as 500/357
i have csc theta as 7/10
i have tan theta as 51/50
sin T = 714/1000
csc T =1/sin T= 1000/714 = 500/357
tan T = 714/700 = 102/100= 51/50
cos T = 7/10
You have them right but mislabeled. | <urn:uuid:eb6c3930-573f-45b6-bc00-e0965de96bc1> | 2.75 | 159 | Q&A Forum | Science & Tech. | 82.479667 | 95,578,934 |
The moiré-fringe method of displacement measurement applied to indirect structural-model analysis
- 164 Downloads
The production of moiré fringes when one grid of equally spaced lines is moved relative to a second similar grid is a well known phenomenon. These fringes may be used to measure the displacements of a transparent structural model if one set of lines is attached to the model and a second set is fixed to a transparent reference screen.
The indirect method of model analysis of structures entails the determination of the influence line for a force or moment at a section in the structure from accurate observations of the displacements of the model which occur when a chosen deformation is applied at the particular section under consideration.
This paper describes the successful application of the moiré-fringe method of displacement measurement to indirect structural-model analysis.
KeywordsMechanical Engineer Fluid Dynamics Indirect Method Displacement Measurement Accurate Observation
List of Symbols
horizontal force Subscripts refer to position of application
moment Subscripts refer to position of application
vertical force Subscripts refer to position of application
distance between adjacent line
distance between adjacent fringes
applied horizontal displacement
applied vertical displacement
- \(\delta _\phi \)
applied rotational displacement
acute angle between two sets of lines
Unable to display preview. Download preview PDF.
- 1.Weller, R., andShepard, B. M., “Displacement Measurement by Mechanical Interferometry,”Proc. Soc. Exptl. Stress Anal., VI (1),35–39 (1948).Google Scholar
- 2.Durelli, A. J., and Daniel, I. M., “Structural Model Analysis by means of Moiré Fringes.Proc. A.S.C.E.,86 (ST 12), (Dec. 1960).Google Scholar
- 3.Beggs, G. E., “An Accurate Mechanical Solution of Statically Indeterminate Structures by use of Paper Models and Special Gauges,”Proc. A.C.J., 18, 58–82 (1922).Google Scholar
- 4.Eney, W. J., “A Large Displacement Deformeter Apparatus for Stress Analysis with Elastic Models,”Proc. Soc. Exptl. Stress Anal., VI (2),84–93 (1948).Google Scholar
- 5.Hetenyi, M., “Handbook of Experimental Stress Analysis,”Wiley & Co., New York, 665–667 (1950).Google Scholar
- 6.Charlton, T. M., “Model Analysis of Structures,”E. and F. N. Spon, Ltd., London (1954).Google Scholar
- 7.Wensley, L. McD., “The Moiré Method of Determining Displacements in Structural Models”Unpublished M.E. Thesis, Univ. of Canterbury, New Zealand (1963).Google Scholar | <urn:uuid:89cd9a7e-df5e-4796-ad97-8b5efa985e32> | 2.640625 | 649 | Academic Writing | Science & Tech. | 49.482493 | 95,578,967 |
Carbon offsets are increasingly seen as a tool to support Sustainable Development Goals (SDGs), as well as mitigate climate change, according to a new report from Forest Trends’ Ecosystem Marketplace, Not So Niche: Co-benefits at the Intersection of Forest Carbon and Sustainable Development.
The report was based on responses to EM’s 2015 survey of forest carbon project developers from across the globe, 81 of whom reported on these multiple benefits. Collectively, these initiatives delivered the following impacts in 2014:
- Clarifying land tenure for communities across 2.2 million (M) hectares of land;
- Preserving biodiversity by protecting the habitats of 141 vulnerable or endangered species; and,
- Creating nearly 8,000 jobs and training over 46,000 people in skills such as agroforestry and carbon accounting and monitoring.
Figure 1: Number of Projects Responding to Questions within Impact Categories | <urn:uuid:15c3ffc9-a160-4685-97f9-39df350f2dc7> | 3.0625 | 185 | Knowledge Article | Science & Tech. | 14.536412 | 95,578,969 |
Plot has a diamond shape, its side is 25.6 m long and the distance of the opposite sides is 22.2 meters. Calculate its acreage.
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Combine like terms 4c+c-7c | <urn:uuid:87ffa22c-ac34-4c09-a84b-007073798d5d> | 3.25 | 560 | Tutorial | Science & Tech. | 86.263429 | 95,579,018 |
Role of water in plasticity, stability, and action of proteins: the crystal structures of lysozyme at very low levels of hydration.Nagendra, H.G., Sukumar, N., Vijayan, M.
(1998) Proteins 32: 229-240
- PubMed: 9714162
- Primary Citation of Related Structures:
- PubMed Abstract:
- Comparison of Radiation Induced Decay and Structure Refinement from X-Ray Data Collected from Lysozyme Crystals at Low and Ambient Temperatures
Young, A.C.M.,Dewan, J.C.,Nave, C.,Tilton, R.F.
(1993) J.Appl.Crystallogr. 26: 309
- Characterization of Lysozyme Crystals with Unusually Low Solvent Content
Nagendra, H.G.,Sudarsanakumar, C.,Vijayan, M.
(1995) Acta Crystallogr.,Sect.D 51: 390
- Protein Hydration and Water Structure: X-Ray Analysis of a Closely Packed Protein Crystal with Very Low Solvent Content
Madhusudan,Kodandapani, R.,Vijayan, M.
(1993) Acta Crystallogr.,Sect.D 49: 234
- Crystal Structure of Low Humidity Tetragonal Lysozyme at 2.1-A Resolution. Variability in Hydration Shell and its Structural Consequences
Kodandapani, R.,Suresh, C.G.,Vijayan, M.
(1990) J.Biol.Chem. 265: 16126
Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur durin ...
Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur during enzyme action, thus highlighting the relationship among hydration, plasticity, and action of these enzymes. Monoclinic lysozyme retains its crystallinity even when the level of hydration is reduced further below that necessary for activity (about 0.2 gram of water per gram of protein). In order to gain insights into the role of water in the stability and the plasticity of the protein molecule and the geometrical basis for the loss of activity that accompanies dehydration, the crystal structures of monoclinic lysozyme with solvent contents of 17.6%, 16.9%, and 9.4% were determined and refined. A detailed comparison of these forms with the normally hydrated forms show that the C-terminal segment (residues 88-129) of domain I and the main loop (residues 65-73) in domain II exhibit large deviations in atomic positions when the solvent content is reduced, although the three-dimensional structure is essentially preserved. Many crucial water bridges between different regions of the molecule are conserved in spite of differences in detail, even when the level of hydration is reduced well below that required for activity. The loss of activity that accompany dehydration appears to be caused by the removal of functionally important water molecules from the active-site region and the reduction in the size of the substrate binding cleft.
Molecular Biophysics Unit, Indian Institute of Science, Bangalore. | <urn:uuid:2e6309c8-81de-4b1e-9771-703c18765417> | 2.53125 | 746 | Knowledge Article | Science & Tech. | 43.12533 | 95,579,035 |
Scientists Develop New methods to estimate the numbers of endangered whales
In recent years, the numbers of the endangered North Atlantic right whales have declined. There are so far 14 famous deaths of these whales. Marine scientists have recently developed a new method to improve the population of these whales.
According to these scientific studies, the number of whales has increased less than three percent every year. The number increased from 270 animals in 1990 to 482 in 2010. Despite this, the percentage of these whales has declined by 99.99 percent since 2010.
Adult females have recorded the biggest decline. They have decreased to a mere 200 whalesin 2010. And they have only further declined to become 186 in 2015. This has lead to the creation of a gap between the number of males and females.
The new statistics provides us with a clearer gesture about the number of North Atlantic right whales. The Current studies and the new statistics proved that the number of these whales has declined since 2010.
The new estimations calculate the number of these whales accurately. These estimations however are not put in consideration most times.
Why was the new statistical model developed?
In the recent years, the North Atlantic right whales changed the place and the time of their past gatherings. This has lead to the decreasing of its sight probability. The North Atlantic right whales that once gathered to feed, and take care of its young recently changed their place of gathering.
This change has lead to makeing the current statistical estimation less credible than the past.leading to the development of a new statistical model to estimate the abundance of these whales.
The Aquarium of New England has conducted searches around the North Atlantic right whales for more than three decades. This Aquarium keeps the data of the whales accurately in a catalog .We depend on these accurate data to estimate the abundance of these whales.
There are a group of researchers who have made annual studies about the North Atlantic right whales. Their studies have been collected in a catalog. These studies are considered a comprehensive enumeration that consists of the photographs of these creatures for the past 25 years.
These researchers managed to photograph the North Atlantic right whales. The total number of these Amazing creatures is 658 whales. Of which 280 of them are females. And the males number at 328. There are also 50 animals of unknown sex.
NOAA Fisheries has issued a warning to fishermen to try and prevent them from crashing into the North Atlantic right whales. Which would lead to more deaths, and injuries in these majestic creatures. | <urn:uuid:e062647e-02ac-4704-8f67-3b8a2b36dab3> | 3.671875 | 506 | Truncated | Science & Tech. | 48.197862 | 95,579,063 |
A measurement is a value which reflects the presence or magnitude of some characteristic. Without measurements there could be no science: indeed, there could be no knowledge. The nature of our knowledge is entirely conditioned by the nature of our measurements. The definitions of physical characteristics that we make, the procedures we choose to evaluate quantity, the representativeness of our observations and the methods we adopt to minimize error of one kind or another are all part of the technique of measurement and they all influence our interpretation of nature. In the environmental sciences, as in other branches of knowledge, an appreciation of the measurement process is fundamental to real understanding of any subject matter. That is the theme of this chapter.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
R. M. Haynes
J. G. Harvey
T. D. Davies
- Springer Netherlands
Fallstudie Überschwemmungskarten/© Thaut Images | Fotolia | <urn:uuid:40dc8be2-8d4b-46c8-b106-58cc7d56a31b> | 3.21875 | 201 | Knowledge Article | Science & Tech. | 30.621451 | 95,579,092 |
June 26, 2015
The day will officially be a bit longer than usual on Tuesday, June 30, 2015, because an extra second, or “leap” second, will be added.
“Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Strictly speaking, a day lasts 86,400 seconds. That is the case, according to the time standard that people use in their daily lives – Coordinated Universal Time, or UTC. UTC is “atomic time” – the duration of one second is based on extremely predictable electromagnetic transitions in atoms of cesium. These transitions are so reliable that the cesium clock is accurate to one second in 1,400,000 years.
Using Quasars to Measure the Earth: A Brief History of VLBI
Video above: Originally developed to study distant astronomical objects called quasars, the technique called Very Long Baseline Interferometry provides information about the relative locations of observing stations and about Earth’s rotation and orientation in space. Video Credits: NASA Goddard Space Flight Center.
However, the mean solar day – the average length of a day, based on how long it takes Earth to rotate – is about 86,400.002 seconds long. That’s because Earth’s rotation is gradually slowing down a bit, due to a kind of braking force caused by the gravitational tug of war between Earth, the moon and the sun. Scientists estimate that the mean solar day hasn’t been 86,400 seconds long since the year 1820 or so.
This difference of 2 milliseconds, or two thousandths of a second – far less than the blink of an eye – hardly seems noticeable at first. But if this small discrepancy were repeated every day for an entire year, it would add up to almost a second. In reality, that’s not quite what happens. Although Earth’s rotation is slowing down on average, the length of each individual day varies in an unpredictable way.
The length of day is influenced by many factors, mainly the atmosphere over periods less than a year. Our seasonal and daily weather variations can affect the length of day by a few milliseconds over a year. Other contributors to this variation include dynamics of the Earth’s inner core (over long time periods), variations in the atmosphere and oceans, groundwater, and ice storage (over time periods of months to decades), and oceanic and atmospheric tides. Atmospheric variations due to El Niño can cause Earth’s rotation to slow down, increasing the length of day by as much as 1 millisecond, or a thousandth of a second.
Scientists monitor how long it takes Earth to complete a full rotation using an extremely precise technique called Very Long Baseline Interferometry (VLBI). These measurements are conducted by a worldwide network of stations, with Goddard providing essential coordination of VLBI, as well as analyzing and archiving the data collected.
The time standard called Universal Time 1, or UT1, is based on VLBI measurements of Earth’s rotation. UT1 isn’t as uniform as the cesium clock, so UT1 and UTC tend to drift apart. Leap seconds are added, when needed, to keep the two time standards within 0.9 seconds of each other. The decision to add leap seconds is made by a unit within the International Earth Rotation and Reference Systems Service.
Typically, a leap second is inserted either on June 30 or December 31. Normally, the clock would move from 23:59:59 to 00:00:00 the next day. But with the leap second on June 30, UTC will move from 23:59:59 to 23:59:60, and then to 00:00:00 on July 1. In practice, many systems are instead turned off for one second.
Extra second illustration
Previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether. One reason is that the need to add a leap second cannot be anticipated far in advance.
“In the short term, leap seconds are not as predictable as everyone would like,” said Chopo Ma, a geophysicist at Goddard and a member of the directing board of the International Earth Rotation and Reference Systems Service. “The modeling of the Earth predicts that more and more leap seconds will be called for in the long-term, but we can’t say that one will be needed every year.”
From 1972, when leap seconds were first implemented, through 1999, leap seconds were added at a rate averaging close to one per year. Since then, leap seconds have become less frequent. This June’s leap second will be only the fourth to be added since 2000. (Before 1972, adjustments were made in a different way.)
Scientists don’t know exactly why fewer leap seconds have been needed lately. Sometimes, sudden geological events, such as earthquakes and volcanic eruptions, can affect Earth’s rotation in the short-term, but the big picture is more complex.
VLBI tracks these short- and long-term variations by using global networks of stations to observe astronomical objects called quasars. The quasars serve as reference points that are essentially motionless because they are located billions of light years from Earth. Because the observing stations are spread out across the globe, the signal from a quasar will take longer to reach some stations than others. Scientists can use the small differences in arrival time to determine detailed information about the exact positions of the observing stations, Earth’s rotation rate, and our planet’s orientation in space.
Current VLBI measurements are accurate to at least 3 microseconds, or 3 millionths of a second. A new system is being developed by NASA’s Space Geodesy Project in coordination with international partners. Through advances in hardware, the participation of more stations, and a different distribution of stations around the globe, future VLBI UT1 measurements are expected to have a precision better than 0.5 microseconds, or 0.5 millionths of a second.
“The next-generation system is designed to meet the needs of the most demanding scientific applications now and in the near future,” says Goddard’s Stephen Merkowitz, the Space Geodesy Project manager.
NASA manages many activities of the International VLBI Service for Geodesy and Astrometry including day-to-day and long-term operations, coordination and performance of the global network of VLBI antennas, and coordination of data analysis. NASA also directly supports the operation of six global VLBI stations.
Proposals have been made to abolish the leap second. No decision about this is expected until late 2015 at the earliest, by the International Telecommunication Union, a specialized agency of the United Nations that addresses issues in information and communication technologies.
For more information about NASA's Space Geodesy Project, including VLBI, visit: http://space-geodesy.nasa.gov/
Image, Video (mentioned), Text, Credits: NASA’s Goddard Space Flight Center/Elizabeth Zubritsky/Lynn Jenner.
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[Gr.,=uncuttable (indivisible)], basic unit of matter; more properly, the smallest unit of a chemical element having the properties of that element.
The atom consists of a central, positively charged core, the nucleus, and negatively charged particles called electrons that are found in orbits around the nucleus.
Almost the entire mass of the atom is concentrated in the nucleus, which occupies only a tiny fraction of the atom's volume. The nucleus of an atom consists of neutrons and protons, the neutron being an uncharged particle and the proton a positively charged one. Their masses are almost equal. Atoms containing the same number of protons but different numbers of neutrons represent different forms, or isotopes, of the same element.
Surrounding the nucleus of an atom are its electrons; for a neutral atom, the number of electrons is equal to the atomic number. The outermost electrons of an atom determine its chemical and electrical properties. An atom may combine chemically with another atom in various ways, either by giving up or receiving electrons, thus setting up an electrical attraction between the atoms (see ion), or by sharing one or more pairs of electrons (see chemical bond). Because metals have few outermost electrons and tend to give them up easily, they are good conductors of electricity or heat (see conduction).
The electrons are often described as revolving about the nucleus as the planets revolve about the sun. This picture, however, is misleading. The quantum theory has shown that all particles in motion also have certain wave properties. For a particle the size of an electron, these properties are of considerable importance. As a result the electrons in an atom cannot be pictured as localized in space, but rather should be viewed as smeared out over the entire orbit so that they form a cloud of charge. The electron clouds around the nucleus represent regions in which the electrons are most likely to be found. The shapes of these clouds can be very complex, in marked contrast to the simple elliptical orbits of planets. Surprisingly, the sizes of all atoms are comparable, in spite of the large differences in the number of electrons they contain.
The atomic number of an atom is simply the number of protons in its nucleus. The atomic weight of an atom is given in most cases by the mass number of the atom, equal to the total number of protons and neutrons combined. An atom may be conveniently symbolized by its chemical symbol with the atomic number and mass number written as subscript and superscript, respectively. For example, the symbol for uranium is U (atomic number 92); the isotopes of uranium with atomic weights 235 and 238 are indicated by and .
The atomic theory, which holds that matter is composed of tiny, indivisible particles in constant motion, was proposed in the 5th cent. B.C. by the Greek philosophers Leucippus and Democritus and was adopted by the Roman Lucretius. However, Aristotle did not accept the theory, and it was ignored for many centuries. Interest in the atomic theory was revived during the 18th cent. following work on the nature and behavior of gases (see gas laws).
Modern atomic theory begins with the work of John Dalton, published in 1808. He held that all the atoms of an element are of exactly the same size and weight (see atomic weight) and are in these two respects unlike the atoms of any other element. He stated that atoms of the elements unite chemically in simple numerical ratios to form compounds. The best evidence for his theory was the experimentally verified law of simple multiple proportions, which gives a relation between the weights of two elements that combine to form different compounds.
Evidence for Dalton's theory also came from Michael Faraday's law of electrolysis. A major development was the periodic table, devised simultaneously by Dmitri Mendeleev and J. L. Meyer, which arranged atoms of different elements in order of increasing atomic weight so that elements with similar chemical properties fell into groups. By the end of the 19th cent. it was generally accepted that matter is composed of atoms that combine to form molecules.
In 1911, Ernest Rutherford developed the first coherent explanation of the structure of an atom. Using alpha particles emitted by radioactive atoms, he showed that the atom consists of a central, positively charged core, the nucleus, and negatively charged particles called electrons that orbit the nucleus. There was one serious obstacle to acceptance of the nuclear atom, however. According to classical theory, as the electrons orbit about the nucleus, they are continuously being accelerated (see acceleration), and all accelerated charges radiate electromagnetic energy. Thus, they should lose their energy and spiral into the nucleus.
This difficulty was solved by Niels Bohr (1913), who applied the quantum theory developed by Max Planck and Albert Einstein to the problem of atomic structure. Bohr proposed that electrons could circle a nucleus without radiating energy only in orbits for which their orbital angular momentum was an integral multiple of Planck's constant h divided by 2π. The discrete spectral lines (see spectrum) emitted by each element were produced by electrons dropping from allowed orbits of higher energy to those of lower energy, the frequency of the photon of light emitted being proportional to the energy difference between the orbits.
Around the same time, experiments on x-ray spectra (see X ray) by H. G. J. Moseley showed that each nucleus was characterized by an atomic number, equal to the number of unit positive charges associated with it. By rearranging the periodic table according to atomic number rather than atomic weight, a more systematic arrangement was obtained. The development of quantum mechanics during the 1920s resulted in a satisfactory explanation for all phenomena related to the role of electrons in atoms and all aspects of their associated spectra. With the discovery of the neutron in 1932 the modern picture of the atom was complete.
With many of the problems of individual atomic structure and behavior now solved, attention has turned to both smaller and larger scales. On a smaller scale the atomic nucleus is being studied in order to determine the details of its structure and to develop sources of energy from nuclear fission and fusion (see nuclear energy), for the atom is not at all indivisible, as the ancient philosophers thought, but can undergo a number of possible changes. On a larger scale new discoveries about the behavior of large groups of atoms have been made (see solid-state physics). The question of the basic nature of matter has been carried beyond the atom and now centers on the nature of and relations between the hundreds of elementary particles that have been discovered in addition to the proton, neutron, and electron. Some of these particles have been used to make new types of exotic "atoms" such as positronium (see antiparticle) and muonium (see muon).
- See The Atom and Its Nucleus (1961). ,
- H. A. Boorse and L. Motz, ed., The World of the Atom (2 vol., 1966).
- Physics of Atoms and Molecules (1986). ; ,
Classically one of the minute, indivisible, homogeneous material particles of which material objects are composed (see Atomism ), and in...
A concept originally introduced by the ancient Greeks (as a tiny indivisible component of matter), developed by Dalton (as the smallest part of...
Chemistry : 1. The smallest unit of a chemical element that can still retain the properties of that element. Atoms combine to form... | <urn:uuid:045c09f0-1c09-43ab-bce3-4445645c57c2> | 4.125 | 1,529 | Knowledge Article | Science & Tech. | 39.523923 | 95,579,137 |
Research Area block
Humans depend on the ocean to help stabilize the climate, provide food and support livelihoods.
Stanford Woods Institute researchers are finding ways to meet challenges facing ocean health by applying the best available science and policy expertise to ocean governance, ecosystem resilience, climate change impacts such as ocean acidification and sea level rise and other stressors to marine environments.
Research Centers and Programs
The Stanford Center for Ocean Solutions (COS) creates innovations to sustain the resilience of the world's oceans and the people who depend on them.
The Natural Capital Project melds world-class research on environmental economics with influential conservation programs. The center’s Integrated Valuation of Environmental Services and Tradeoffs (InVEST) software suite enables decision-makers to quantify nature’s values, assess tradeoffs associated with alternative land- and water-use choices and integrate conservation and human development into land- and...
Other Research Centers and Programs
Environmental Venture Projects
This project will develop, test and deploy novel methods of displaying complex data through sound.
Coral reefs are enormously important for biodiversity, CO2 absorption, fisheries, and protection of coastlines from storm surges. Although corals are animals, they host photosynthetic algae in an essential symbiotic relationship. Corals face many threats, including rising seawater temperatures and pollution; exposure to sunscreens may be another.
Realizing Environmental Innovation Program
Understanding the increasing risk posed by coastal floods and erosion and the benefits of natural defenses, such as reef and wetland restoration, is critical to governments and private industry.
News & Press Releases
Noah Diffenbaugh's study on climate change and severe weather events is mentioned.
By Andrew Freedman,
Temporal variability in thermally-driven cross-shore exchange: the role of semidiurnal tides »
A Novel Cardiotoxic Mechanism for a Pervasive Global Pollutant » | <urn:uuid:47db4482-93ed-40f1-9081-fc2c6a9e2e23> | 2.71875 | 390 | Content Listing | Science & Tech. | 8.923364 | 95,579,138 |
An unknown salt is either NaF, NaCl or NaOCl.When 0.050 mol of the salt is dissolved in water for form 0.500 L of solution, the pH of the solution is 8.08. What is the identity of the salt?
Find the best study resources around, tagged to your specific courses. Share your own to gain free Course Hero access.
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"Microbial fuel cells show promise for conversion of organic wastes and renewable biomass to electricity, but further optimization is required for most applications," says Derek Lovley of the University of Massachusetts in Amherst. Earlier this month, Lovley announced at a meeting that he and his colleagues were able to achieve a 10-fold increase in electrical output by allowing the bacteria in microbial fuel cells to grow on biofilms on the electrodes of a fuel cell.
This week, Gemma Reguera, a researcher in Lovley’s lab will present data identifying for the first time how these bacteria are able to transfer electrons through the biofilms to the electrodes.
"Cells at a distance from the anode remained viable with no decrease in the efficiency of current production as the thickness of the biofilm increased. These results are surprising because Geobacter bacteria do not produce soluble molecules or ’shuttles’ that could diffuse through the biofilm and transfer electrons from cells onto the anode," says Reguera.
She and her colleagues discovered that the bacteria produce conductive protein filaments, or pili ’nanowires,’ to transfer electrons. The finding that pili can extend the distance over which electrons can be transferred suggests additional avenues for genetically engineering the bacteria to further enhance power production.
Researchers from the Universidad Nacional Autonoma de Mexico announce that they have genetically engineered the bacterium Bacillus subtilis to directly ferment glucose sugar to ethanol with a high (86%) yield. This is the first step in a quest to develop bacteria that can breakdown and ferment cellulose biomass directly to ethanol.
"Currently ethanol is produced primarily from sugarcane or cornstarch, but much more biomass in the whole plant, including stems and leaves, can be converted to ethanol using clean technology," says Aida-Romero Garcia, one of the researchers on the study. The next step is to engineer the bacteria to produce the enzymes, known as cellulases, to break the stems and leaves down into the simple carbohydrates for fermentation.
Bacteria can not only produce alternative fuels, but could also aid in oil production by boosting output of existing wells. Michael McInerney and his colleagues at the University of Oklahoma will present research demonstrating the technical feasibility of using detergent-producing microorganisms to recover entrapped oil from oil reservoirs.
"Our approach is to use microorganisms that make detergent-like molecules (biosurfactants) to clean oil off of rock surfaces and mobilize oil stuck in small cavities. However, up till now, it is not clear whether microorganisms injected into an oil reservoir will be active and whether they will make enough biosurfactant to mobilize entrapped oil," says McInerney.
He and his colleagues were able to inoculate an oil reservoir with specific strains of bacteria and have these bacteria make biosurfactants in amounts needed for substantial oil recovery.
"We now know that the microorganisms will work as intended in the oil reservoir. The next important question is whether our approach will recover entrapped oil economically. We saw an increase in oil production after our test, but we need to measure oil production more precisely to be certain," says McInerney.
Jim Sliwa | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
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MBL Neurobiology Course Students Contribute to Probe’s Development
With Scientists from UC-Davis and Lawrence Berkeley National Laboratory
Crucial experiments to develop a novel probe of cellular electrical activity were conducted in the Neurobiology course at the Marine Biological Laboratory (MBL) in 2013. Today, that optical probe, which combines a tarantula toxin with a fluorescent compound, is introduced in a paper in the Proceedings of the National Academy of Sciences.
The movie is quantitative imaging of cells with potassium channels, bathed in dilute fluorescent tarantula toxin. Pixel color indicates intensity of tarantula toxin concentration. The circular shapes are cell surfaces, illuminated by tarantula toxins bound to potassium channels. The cell on the right is electrically stimulated to the indicated voltages. The cells on the left remain at constant resting voltage. Intensity change reports activation of potassium channels. At -100 mV channels are at rest. During stimulus to 0 mV channels activate and fluorescence decreases as tarantula toxins fall off of potassium channels. Upon return to -100 mV, tarantula toxins find the resting channels again.
The lead authors of the paper are Drew C. Tilley of University of California-Davis and the late Kenneth Eum, who was a teaching assistant in the Neurobiology course and a Ph.D. candidate at UC-Davis.
The probe takes advantage of the potent ability of tarantula toxin to bind to electrically active cells, such as neurons, while the cells are in a resting state. The team discovered that a trace amount of toxin combined with a fluorescent compound would bind to a specific subset of voltage-activated proteins (Kv2-type potassium ion channels) in live cells. The probe lights up cell surfaces with this ion channel, and the fluorescent signal dims when the channel is activated by electrical signals.
This is the first time that researchers have been able to visually observe these ion channels “turning on” without first genetically modifying them. All that is required is a means to detect probe location, suggesting that related probes could potentially one day be used to map neural activity in the human brain.
“This is a demonstration, a prototype probe. But the promise is that we could use it to measure the activity state of the electrical system in an organism that has not been genetically compromised,” says senior author Jon Sack, an assistant professor in the departments of Physiology and Membrane Biology at UC-Davis. Sack is a faculty member in the MBL Neurobiology course.
Since the probe binds selectively to one of the many different kinds of ion channels, it can help scientists disentangle the function of those specific channels in neuronal signaling. This can, in turn, lead to the identification of drug targets for neurological diseases and disorders.
“We have an incredible diversity of ion channels, and even of voltage-activated ion channels. The real trouble has been determining which ones perform which roles. Which ones turn on and when in normal nervous system functioning? Which are involved in abnormal states or syndromes?” Sack says. “The dream is to be able to see what the different types of ion channels are doing and when, to understand what they contribute to physiology and pathophysiology.”
These probes respond to movement of ion channel voltage sensors, and it is particularly fulfilling to have conducted some of this work at the MBL, Sack says. The first measurements of voltage sensor movement were conducted at the MBL in the early 1970s by Clay M. Armstrong and Francisco Bezanilla (Nature 242: 459-461, 1973). Armstrong and Bezanilla used electrophysiological methods to measure the movement of voltage sensors. The spider toxin probe create an optical signal when voltage sensors move, and no electrophysiology or genetic mutation of the channels is required.
Tilley DC, Eum KS, Fletcher-Taylor S, Austin DC, Dupré C, Patrón LA, Garcia RL, Yarov-Yarovoy V, Cohen BE, and Sack JT (2014) Chemoselective tarantula toxins report voltage activation of wild-type ion channels in live cells. PNAS doi: www.pnas.org/cgi/doi/10.1073/pnas.1406876111.
For more information, please see the UC-Davis press release.
Recorded by Kenneth Eum, Lillian Patrón, and Christophe Dupré in the MBL Neurobiology course
The Marine Biological Laboratory (MBL) is dedicated to scientific discovery and improving the human condition through research and education in biology, biomedicine, and environmental science. Founded in Woods Hole, Massachusetts, in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.
Diana Kenney | Eurek Alert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Materials Sciences
19.07.2018 | Earth Sciences
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Lost City Hydrothermal Field
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The hydrothermal field differs significantly from the black smoker vents found in the late 1970s. The vents were discovered in December 2000 during a National Science Foundation expedition to the mid-Atlantic. A second expedition mounted in 2003 used DSV Alvin to explore the vents. The details of the chemistry and biology of the Lost City hydrothermal field were published in March 2005.
A similar alkaline hydrothermal vent, the Strytan Hydrothermal Field, has been identified off the north coast of Iceland.
The vents are located on the seafloor mountain Atlantis Massif, where reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids that are highly alkaline (pH 9 to 11), with temperatures ranging from <40° to 90 °C. There is a field of about 30 chimneys made of calcium carbonate 30 to 60 meters tall, with a number of smaller chimneys.
Lost City vents release methane and hydrogen into the surrounding water; they do not produce significant amounts of carbon dioxide, hydrogen sulfide or metals, which are the major outputs of volcanic black smoker vents. The temperature and pH of water surrounding the two types of vent is also significantly different. Strontium, carbon, and oxygen isotope data and radiocarbon ages document at least 30,000 years of hydrothermal activity driven by serpentinization reactions at Lost City, making the Lost City older than known black smoker vents by at least two orders of magnitude. Correspondingly, Lost City and black smoker vents support vastly different lifeforms.
The Lost City supports a variety of small invertebrates associated with the carbonate structures, including snails, bivalves, polychaetes, amphipods, and ostracods. Large animals, however, such as tube worms and giant clams that are abundant in typical black smoker vents are absent at Lost City. A variety of microorganisms live in, on, and around the vents. Methanosarcinales-like archaea form thick biofilms inside the vents where they subsist on hydrogen and methane; bacteria related to the Firmicutes also live inside the vents. External to the vents archaea, including the newly described ANME-1 and bacteria including proteobacteria oxidise methane and sulfur as their primary source of energy.
Speculation has been offered that ancient versions of similar hydrothermal vents in the seas of a young Earth are the birthplace of all life, constituting the original abiogenesis. The free hydrogen, metallic catalysts consistent with an iron-sulfur world theory, micro-cellular physical structure of the towers and available hydrothermal energy might plausibly have provided an environment for the beginnings of non-photosynthetic energy cycles common to archaea and organic molecule creation. Microscopic structures in such alkaline vents "show interconnected compartments that provide an ideal hatchery for the origin of life". These alkaline hydrothermal vents also continuously generate acetyl thioesters, providing both the starting point for more complex organic molecules and the energy needed to produce them. However, this notion was rejected by Japanese researchers from Earth-Life Science Institute (ELSI), Tokyo Institute of Technology. They showed that the high free energy change of thioesters hydrolysis and corresponding to their low equilibrium constants, it is unlikely that these species could have accumulated abiotically to any significant extant in the Lost City fields.
- Price, Roy. "The Strytan Hydrothermal Field (SHF), Eyjafjord, Iceland". Stony Brook University. Retrieved 23 October 2016.
- Science Magazine, Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field February 2008 http://www.sciencemag.org/cgi/content/short/319/5863/604
- Proceedings of the Royal Society, On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells 5 December 2002 http://rstb.royalsocietypublishing.org/content/358/1429/59.full.pdf
- Lane, N. (2010). Life Ascending: the 10 great inventions of evolution. Profile Books. ISBN 978-0-393-33866-9.
- Chandru, Kuhan; Gilbert, Alexis; Butch, Christopher; Aono, Masashi; Cleaves, H. James (21 July 2016). "The Abiotic Chemistry of Thiolated Acetate Derivatives and the Origin of Life". Scientific Reports. 6 (Article number: 29883): 29883. Bibcode:2016NatSR...629883C. doi:10.1038/srep29883. PMC . PMID 27443234.
- Boetius, Antje (2005-03-04). "Lost City Life" (PDF). Science. AAAS. 307 (5714): 1420–1422. doi:10.1126/science.1109849.
- Bradley, A. Alexander (December 2009). "Expanding the Limits of Life". Scientific American: 62–67.
- Brazelton, W. J.; et al. (2010-01-11). "Archaea and bacteria with surprising microdiversity show shifts in dominance over 1,000-year time scales in hydrothermal chimneys". PNAS. NAS. 107 (4): 1612–1617. Bibcode:2010PNAS..107.1612B. doi:10.1073/pnas.0905369107. PMC . PMID 20080654.
- "Hydrogen and methane provide raw energy for life at 'Lost City". EurekAlert!. 3 March 2005.
- Früh-Green, G.L.; et al. (2003-07-25). "30,000 Years of Hydrothermal Activity at the Lost City Vent Field". Science. AAAS. 301 (5632): 495–498. Bibcode:2003Sci...301..495F. doi:10.1126/science.1085582. PMID 12881565.
- Kelley, D. S.; et al. (2005-03-04). "A Serpentinite-Hosted Ecosystem: The Lost City Hydrothermal Field". Science. AAAS. 307 (5714): 1428–1434. Bibcode:2005Sci...307.1428K. doi:10.1126/science.1102556. PMID 15746419.
- Proskurowski, G.; et al. (2008-02-01). "Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field". Science. AAAS. 319 (5863): 604–607. doi:10.1126/science.1151194. PMID 18239121. | <urn:uuid:a9694583-046e-435f-ab6e-7aa2feeddf13> | 3.203125 | 1,465 | Knowledge Article | Science & Tech. | 55.879228 | 95,579,196 |
A team of American astronomers announced today (Tuesday, Nov. 6) the discovery of a record-breaking fifth planet around the nearby star 55 Cancri, making it the only star aside from the sun known to have five planets.
The discovery comes after 19 years of observations of 55 Cancri and represents a milestone for the California and Carnegie Planet Search team, which this year celebrates the 20th anniversary of its first attempts to find extrasolar planets by analyzing the wobbles they cause in their host star.
The team's long history of measurements - more than 300 for 55 Cancri alone - made the discovery of a five-planet system possible, said UC Berkeley astronomy professor Geoffrey Marcy, who with Paul Butler, now at the Carnegie Institution of Washington, began observations of many nearby stars at the University of California Lick Observatory in 1987.
The unique 55 Cancri system, located 41 light-years away in the direction of the constellation Cancer, is notable also because its clutch of four inner planets and one giant outer planet resembles our own solar system, though without an Earth or Mars.
"This system is interesting because there's a giant planet at 6 AU and four smaller planets inward of 0.8 AU, with a huge remaining gap in between, right where we would expect to find an Earth-sized planet," Marcy said.
An AU, or astronomical unit, is the average distance between the Earth and the sun, about 93 million miles.
According to lead author Debra Fischer, assistant professor of astronomy at San Francisco State University, the fifth planet is within the star's habitable zone in which water could exist as a liquid. Though the planet is a giant ball of gas, liquid water could exist on the surface of a moon or on other, rocky planets that may yet be found within the zone. "Right now, we are looking at a gap between the 260-day orbit of the new planet and the 14-year orbit of another gas giant, and if you had to bet, you'd bet that there is more orbiting stuff there."
Fischer noted that what occupies this gap has to be another planet around the size of Neptune or smaller, because anything larger would have destabilized the orbits of the other planets. All of the planets around 55 Cancri are in stable, nearly circular obits, like the eight planets in our solar system. Jupiter is located at 5.2 AU from the sun, while Mercury and Venus are closer than 0.72 AU. Earth and Mars are in the gap at 1 AU and 1.5 AU.
"We haven't found a twin of our solar system, because the four planets close to the star are all the size of Neptune or bigger," Marcy said, but he added that he's optimistic that continued observations will reveal a rocky planet within five years.
The new discovery, using data from the Lick Observatory and the W. M. Keck Observatory in Hawaii, has been accepted for publication in the Astrophysical Journal. The authors are Fischer, Marcy and their colleagues at the Carnegie Institution, San Francisco State University, UC Santa Cruz, Tennessee State University and UC Berkeley.
Fischer and Marcy also discussed their findings today during a media teleconference hosted by NASA.
"This work marks an exciting next step in the search for worlds like our own," said Michael Briley, an astronomer at the National Science Foundation. "To go from the first detections of planets around sun-like stars to finding a full-fledged solar system with a planet in a habitable zone in just 12 years is an amazing accomplishment and a testament to the years of hard work put in by these investigators."
In 1996, when Marcy and Butler found a Jupiter-sized planet orbiting close to 55 Cancri and circling every 14.6 days, it was only the fourth known star with an exoplanet. The second planet discovered in 2002 around the star turned out to circle in a more distant orbit, like our own Jupiter does, although the planet was four times the weight of Jupiter. The third, also discovered in 2002, was smaller, about half the size of Saturn, and was orbiting near the star with an orbit of 44 days, slightly farther than the first planet. The fourth planet, found in 2004, was so close to the star as to be hellishly hot - a Neptune-sized planet (14 times Earth's mass) with a 2.8 day period discovered in collaboration with a team led by Barbara McArthur of the University of Texas.
Although astronomers have found nearly 250 exoplanets, only one other star, mu Ara in the southern sky, is known to have four planets.
The newly-found fifth planet around 55 Cancri is also large - around half the size of Saturn, or at least 45 times the mass of Earth - and orbiting at about 0.785 AU in 260.8 days. Because the star 55 Cancri is older and dimmer than our sun, the habitable zone - the region in which planetary temperatures can be favorable for liquid water - is closer to the star than is our sun's habitable zone, and includes the new planet.
Finding multiple planets around a star is difficult because each planet produces its own stellar wobble. Marcy compares detecting the wobble within wobbles that are caused by one of several planets to picking out a single musical note from many played simultaneously. While the ear can do that, it took Marcy more than 10 months to convince himself that a fifth wobble was buried in the data.
The Doppler technique used by the search team sees this wobble as a change in the speed with which a star moves toward or away from us. The search team can detect velocities as small as 1 meter per second, which is walking speed.
55 Cancri has produced "a rat's nest of radial velocity data," Fischer said. "We probably still don't have all the planets. We are pulling out one thread at a time, disentangling all these orbits, and it has taken a lot more data and time than we predicted. I think it's amazing what we have been able to do with the system."
Robert Sanders | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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03.07.2018 | Event News
20.07.2018 | Materials Sciences
20.07.2018 | Physics and Astronomy
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Butane is the simplest alkane fuel for which more than a single structural isomer is possible. In the present study, n-butane and isobutane are used in a test engine to examine the importance of molecular structure in determining knock tendency, and the experimental results are interpreted using a detailed chemical kinetic model. A sampling valve was used to extract reacting gases from the combustion chamber of the engine. Samples were withdrawn at different times during the engine cycle, providing concentration histories of a wide variety of reactant, olefin, carbonyl, and other intermediate and product species. The chemical kinetic model predicted the formation of all the intermediate species measured in the experiments. The agreement between the measured and predicted values is mixed and is discussed.
Calculations show that RO2 isomerization reactions are more important contributors to chain branching in the oxidation of n-butane than in isobutane. Chain branching in isobutane oxidation is dependent on H-atom abstraction reactions involving HO2 and CH3O2 radicals that occur at higher temperatures than RO2 isomerization reactions. Therefore, an isobutane mixture must be raised to a higher temperature than a n-butane mixture to achieve the same overall rate of reaction. | <urn:uuid:c10eff97-2898-4e13-a60b-15bc4e27a5d5> | 2.734375 | 254 | Academic Writing | Science & Tech. | 10.264478 | 95,579,201 |
Classification of Several Optically Complex Waters in China Using in Situ Remote Sensing Reflectance
AbstractDetermining the dominant optically active substances in water bodies via classification can improve the accuracy of bio-optical and water quality parameters estimated by remote sensing. This study provides four robust centroid sets from in situ remote sensing reflectance (Rrs (λ)) data presenting typical optical types obtained by plugging different similarity measures into fuzzy c-means (FCM) clustering. Four typical types of waters were studied: (1) highly mixed eutrophic waters, with the proportion of absorption of colored dissolved organic matter (CDOM), phytoplankton, and non-living particulate matter at approximately 20%, 20%, and 60% respectively; (2) CDOM-dominated relatively clear waters, with approximately 45% by proportion of CDOM absorption; (3) nonliving solids-dominated waters, with approximately 88% by proportion of absorption of nonliving particulate matter; and (4) cyanobacteria-composed scum. We also simulated spectra from seven ocean color satellite sensors to assess their classification ability. POLarization and Directionality of the Earth's Reflectances (POLDER), Sentinel-2A, and MEdium Resolution Imaging Spectrometer (MERIS) were found to perform better than the rest. Further, a classification tree for MERIS, in which the characteristics of Rrs (709)/Rrs (681), Rrs (560)/Rrs (709), Rrs (560)/Rrs (620), and Rrs (709)/Rrs (761) are integrated, is also proposed in this paper. The overall accuracy and Kappa coefficient of the proposed classification tree are 76.2% and 0.632, respectively. View Full-Text
Share & Cite This Article
Shen, Q.; Li, J.; Zhang, F.; Sun, X.; Li, J.; Li, W.; Zhang, B. Classification of Several Optically Complex Waters in China Using in Situ Remote Sensing Reflectance. Remote Sens. 2015, 7, 14731-14756.
Shen Q, Li J, Zhang F, Sun X, Li J, Li W, Zhang B. Classification of Several Optically Complex Waters in China Using in Situ Remote Sensing Reflectance. Remote Sensing. 2015; 7(11):14731-14756.Chicago/Turabian Style
Shen, Qian; Li, Junsheng; Zhang, Fangfang; Sun, Xu; Li, Jun; Li, Wei; Zhang, Bing. 2015. "Classification of Several Optically Complex Waters in China Using in Situ Remote Sensing Reflectance." Remote Sens. 7, no. 11: 14731-14756. | <urn:uuid:c0d186a4-b3b2-47cb-8228-7939e0120c91> | 2.640625 | 576 | Academic Writing | Science & Tech. | 42.379205 | 95,579,203 |
Predation is a strong selective force acting on both morphology and behaviour of prey animals. While morphological defences (e.g. crypsis, presence of armours or spines or specific body morphologies) and anti- predator behaviours (e.g. change in foraging or reproductive effort, or hiding and fleeing behaviours) have been widely studied separately, few studies have considered the interplay between the two. The question raised in our study is whether antipredator behaviours of a prey fish to predator odours could be influenced by the morphology of prey conspe- cifics in the diet of the predator. We used goldfish (Carassius auratus) as our test species; goldfish exposed to predation risk significantly increase their body depth to length ratio, which gives them a survival advantage against gape-limited predators. We exposed shallow-bodied and deep-bodied goldfish to the odour of pike (Esox lucius) fed either form of goldfish. Deep-bodied goldfish displayed lower intensity anti- predator responses than shallow-bodied ones, consistent with the hypo- thesis that individuals with morphological defences should exhibit less behavioural modification than those lacking such defences. Moreover, both shallow- and deep-bodied goldfish displayed their strongest anti- predator responses when exposed to the odour of pike fed conspecifics of their own morphology, indicating that goldfish are able to differenti- ate the morphology of conspecifics through predator diet cues. For a given individual, predator threat increases as the prey become more like the individual eaten, revealing a surprising level of sophistication of chemosensory assessment by prey fish.
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The Physics of Accelerators. C.R. Prior Rutherford Appleton Laboratory and Trinity College, Oxford. Contents. Basic concepts in the study of Particle Accelerators Methods of acceleration Linacs and rings Controlling the beam Confinement, acceleration, focusing Electrons and protons
Rutherford Appleton Laboratory
and Trinity College, Oxford
A magnetic field does not alter a particle’s energy. Only an electric field can do this.
SLAC linear accelerator
SNS Linac, Oak Ridge
George Lawrence and cyclotron
Oscillations about the design orbit are called betatron oscillations
B-field on orbit is one half of the average B over the circle. This imposes a limit on the energy that can be achieved. Nevertheless the constant radius principle is attractive for high energy circular accelerators.
e.g. LHC E = 8 TeV, B = 10 T, r= 2.7 km
Variation of parameters with time in the ISIS synchrotron:
Prototype FFAG, accelerating protons from 50keV to 500keV, was successfully built and tested at the KEK laboratory in Japan, 2000.
R = 1100 m, = 225 m
744 dipole magnets, 6.26 m long, angle = 0.48o
Example of longitudinal phase space trajectories under a dual harmonic voltage
Note that there are two stable oscillation centres inside the bucket
i.e. horizontal restoring force is towards the design orbit.
Weak focusing: if used, scale of magnetic components of a synchrotron would be large and costly
Sextupoles are used to correct longitudinal momentum errors.
Effect of a thin lens can be represented by a matrix
In a drift space of length , x is unaltered but x x+x
In an F-drift-D system, combined effect is
Thin lens of focal length f 2/ , focusing overall, if f. Same for D-drift-F ( f - f), so system of AG lenses can focus in both planes simultaneously
Matched beam oscillations in a proton driver for a neutrino factory, with optical functions designed for injection and extraction
Matched beam oscillations in a simple FODO cell
Interaction rate is R = f N2 /A, and | <urn:uuid:eccb6708-9275-4674-b463-8d7f23c1d1d7> | 3.203125 | 479 | Content Listing | Science & Tech. | 46.67619 | 95,579,210 |
Links to descriptions of biology, behaviour, distribution, life histories, and images of
We have a similar problem with butterflies and modern society. We are destroying their foodplants and their habitat. If our grandchildren and future generations are to enjoy the wondrous nature of butterflies: we need to allow Caterpillars to coexist with us in our society.
Caterpillars are the immature stages of butterflies and moths (Lepidoptera). At a recent count, Australia was home to 5 familes of butterflies (containing about 400 named species), and about 100 families of moths (containing over 10,000 named species, with probably as many moth species again yet to be described). Many of the Australian moths and butterflies are very beautiful, and many of their caterpillars are even prettier and more interesting than the their adult forms. Caterpillars are also very tame and easy to catch, and so make delightful house pets.
Most Australian Lepidoptera taxonomy and identification has been performed on dead adult moths sent back to the British Museum in London from Australia by the early explorers. Meanwhile: most professional entomologists in Australia are employed to study the control of the few species that are pests. So for instance: there is no information at all on the shapes, colours, and behaviour of the caterpillars of 90% of Australian moths. So even amateurs can help discover these things by collecting, photographing and rearing in captivity any caterpillars that they find in Australia.
Preserving caterpillars poses difficult problems. This makes the identification of caterpillars difficult. So: of the limited number of Australian Lepidoptera that have known caterpillars: only a small number have been photographed, and still fewer of such photos are on the web. In an attempt to improve this situation: we have created these webpages with all the pictures and links we can find about caterpillars that occur in Australia. The pictures come from ourselves and many colleagues, from a wide variety of sources, and are of very varied quality. We are still adding more pictures, so watch the counts at the head of this webpage.
Did you know:
and some caterpillars in
NOCTUIDAE even have false teeth, like
Link to More Caterpillar Facts.
The fauna and the flora of Australia are very different from those in the rest of the world, and this is just as true of the Caterpillars as it is of the better known Marsupials. With the short history of European influence in Australia and only a small human population, only a limited amount of work has been done on naming and identifying the various species.
Of course, the Australian Aborigines knew a great deal about Australian Lepidoptera, and they used several species as sources of food, for example:
The scientific name for a Caterpillar is Larva (plural Larvae). This name was taken from the Latin word Larva meaning amongst other things 'Mask', because Caterpillars could be thought of as masking the butterflies and moths which they become.
scientific name index
but useful if seeking information on a species for which you know the scientific name
Caterpillars have several thousand muscles and have no skeleton. So by extending or contracting appropriate muscles: caterpillars can change their apparaent length by plus or minus 25%. The wingspan of the adult imago is approximately equal to the maximum length to which the caterpillar grows. Depending on the average temperature, humidity, and availability of food, caterpillar maximum sizes can also vary by plus or minus 25%. Thus the lengths and wingspans given in these webpages for various species of moths and butterflies are implicitly subject to this degree of variability.
The wingspans given in 19th century descriptions are sometimes listed in 'lines' or its abbreviation " (double quote). A line is 1/12th of an inch, approximately equal to 2 mms. By the term 'wingspan' in these webpages is meant the distance between left and right forewing tips of a specimen with the wings set so that the hind margins of the forewings are at right angles to the axis of the body.
Note: that we have adopted three unconventional conventions
in an attempt to make these webpages more understandable to non-entomologists:
1. all scientific names are in italics,
2. all taxonomical levels above genus (such as family, order, class) are in capitals, and
3. all our pictures have the head to the left, although that has required a left-right reflection of some of the photos.
We have generally followed the nomenclature and taxonomic divisions as used in the erudite text :
Checklist of the Lepidoptera of Australia
Nielsen E.S., Edwards E.D. & Rangsi T.V. (Eds)
(529pp + CDROM, CSIRO Publishing, Melbourne, 1996)
These webpages would not be so extensive but for the help of many friends and colleagues, whom we feature on our special
We have a separate webpage for each species, and links to these are available from a webpage for each family as a thumbnail picture and a highlighted name. The families are also linked from one webpage for the moths and one for the butterflies. We have included lots of pictures of the adult butterflies and moths also, even if we had no caterpillar pictures for those species. In these cases, our thumbnail pictures show only an adult. For some species we have found no pictures at all, but only some descriptive text. In these cases, we show only a bullet by the name, and the name is highlighted as the link. Some species have been illustrated on Australian postage stamps, and some more widespread species of Australian butterflies and Australian moths have appeared on overseas stamps.
Many caterpillars are very fussy eaters, and eat only a very restricted range of plants or foodstuffs. We have tried to include links for the known food sources of the various caterpillars. However, we only list those that we have observed, those we have been told about by other observers, and those reported in the literature. In principle, the caterpillars might feed on anything when nobody is looking.
Australian Lepidoptera links
We also have a list of some
Overseas Caterpillar and Lepidoptera links
(written 10 August 1996, updated 21 July 2018) | <urn:uuid:6d64ea5e-49df-444b-9768-f4feee207d4b> | 3.421875 | 1,335 | Content Listing | Science & Tech. | 37.280319 | 95,579,228 |
Global distributions of the ratios of the concentrations of nitrate + nitrite (= [N]) and phosphate (= [P]) are evaluated from Geochemical Ocean Sections Study (GEOSECS) and Transient Tracers in the Ocean (TTO) data sets. If large oceanic regions (or provinces) can be identified on the basis of constant [N]:[P] ratios, then the distribution equation for a reactive variable shows that the ratio of the net reaction rates involving N and P in each one is equal to its concentration ratio. Organisms within the interiors of the provinces would then be in balance with the ratios in which the nutrients are present, producing a non-fractionated or "ideal" nutrient covariation. Such provinces can be observed throughout the ocean, Notable features are as follows: (1) Between the euphotic zone and 500 m in the west central North Atlantic is a large region in which N-P regeneration produces very high [N]:[P] ratios: approximately 50 mol mol-1. Potential causes are 18-degrees Water formation, coccolithophorid growth, nitrogen fixation, or atmospheric fixed-nitrogen deposition. (2) Most oligotrophic surface waters seem to have [N]:[P] between 0 and 3 mol mol-1, implying that the net removal ratio of N and P in those waters is 0-3 mol mol-1. (3) Below 600 m, the ocean contains large provinces with N-P regeneration ratios of 12-18 mol mol-1. The dominant ratio is slightly sub-Redfield at 14.5-15 mol mol-1, with the entire Indian Ocean below 3000 m being ideally covariant at 14.7 mol mol-1. The northeastern Pacific has provinces with very low regeneration ratios (< 14 mol mol-1). Vertical boundaries between deep provinces in the western Pacific and eastern Atlantic suggest that particles from immediately above control regeneration ratios, whereas the more horizontal boundaries between western Atlantic provinces appear to reflect a greater importance of horizontally transported particles in water masses like Antarctic Intermediate Water. N-P reaction rate ratios along deep isopycnal surfaces are quite variable.
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In a study published online in Genome Research (www.genome.org), scientists have performed the first global survey of salivary microbes, finding that the oral microbiome of your neighbor is just as different from yours as someone across the globe.
The human body harbors ten times more bacterial cells than human cells – a stunning figure that suggests a likely dynamic between ourselves and the bacteria we carry, both in healthy and disease states. The National Institutes of Health recently launched an initiative to categorize the microbiomes of several regions of the body, with early studies focusing on the intestines and skin. It is appreciated that the human mouth, a major entry point for bacteria into the body, also contains a diverse array of microbial species. Yet microbiome diversity between individuals, and how this relates to diet, environment, health, and disease, remains unexplored.
In this study, scientists have conducted the first in-depth study of global diversity in a human microbiome, characterizing the microbial life in human saliva from regions around the world. The researchers, led by Dr. Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have sequenced and analyzed variation in the bacterial gene encoding 16S rRNA, a component of the ribosome, in the salivary "metagenome" of 120 healthy subjects from six geographic areas. Stoneking and colleagues then compared the sequences they found with a database of 16S rRNA sequences to categorize the types of bacteria present.
The group observed that there is considerable diversity of bacterial life in the saliva microbiome, both within and between individuals. However, they made an unexpected finding when comparing samples from different geographic areas. "The saliva microbiome does not vary substantially around the world," Stoneking described. "Which seems surprising given the large diversity in diet and other cultural factors that could influence the human salivary microbiome." Stoneking explained that this suggests the life inhabiting the mouth of your next-door neighbor is likely to be just as different from yours as someone on the other side of the world.
Stoneking noted that by studying sequences from an easily obtained saliva sample, their work has provided the foundation for future studies exploring the influence of diet, cultural factors, and disease on variation in the saliva microbiome. In addition, the group's findings could help analyze human migrations and populations. While it may not be pleasant to think about the life teeming in your mouth, it is now evident that we will be able to learn a lot about oral health and disease by understanding what is living there.
Peggy Calicchia | EurekAlert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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Ferromagnetism of Amorphous Iron Alloys
It is well known that ferromagnetism appears in 3d metals (Fe, Co and Ni) and alloys whose average outer electron concentration, N, ranges from about 6.5(Fe-Cr) to 10.6 (Ni-Cu). The saturation magnetization of these metals and alloys is expressed by the so-called Slater Pauling curve. The crystal structure of these alloys in ordinary phases is generally body centered cubic or face centered cubic for N < 8.5 or N > 8.7 respectively. There is some dincontinuity between the saturation moment of bcc alloys and that of fcc alloys. The Curie temperature is much more sensitive to the crystal structure. There are interesting topics for Invar alloys in a region close to the phase boundary between fcc and bcc phase.1 The magnetic properties of metals and alloys are necessarily affected by their crystal structures.
KeywordsCurie Temperature Amorphous Alloy Invar Alloy Random Lattice Metallic Atom
Unable to display preview. Download preview PDF.
- 3.P. Pietrokowsky: Rev. Sei. Inst. 34 (1963) 445. P. Duwez: Prog. Solid State Chem. 3 (1966) 377.Google Scholar | <urn:uuid:5014d701-e701-4ec6-9ca6-26638b5bf225> | 2.5625 | 276 | Truncated | Science & Tech. | 55.169195 | 95,579,265 |
Energy equals mass times the speed of light squared
Scientist Tom Van Flandern is gone now but a paper of his is still here: you can get it by clicking this linkVan Flandern
"When you square a speed, you get energy,"wrote VanFlandern later, in an e-mail to me.
Gravity travels far faster than light. As far as NASA is concerned gravity travels instantly.Van Flandern shows us the speed of gravitational attraction is greater than or equal to 2 x 1010c. This translated for the non mathematical reader means, for a stable universe, gravity travels at least or more than 20 billion times the speed of light. (That's using American billion, not the English billion.)
First, scientists know ALL electron magnetic type forces like light and ordinary magnetic force all travel at c, or the speed of light.
Again: gravity travels far faster than light. Gravity travels instantly or, asVan Flandern shows us, at least 20 billion times the speed of light.
Second, free electrons can never attract each other. They always REPEL each other. Only quark harmonically captured, orbital electrons can attract other similar electrons (depending on their spin orientation) or they can attract free electrons.
This showed me the supreme importance of the harmonic aspect of all of this.
This harmonic aspect between the electron and quark is the reason gravity can bend light because light is electron generated and gravity is quark generated.
Many years ago I read this paper written by Tom Van Flandern and saw, that since quarks had a faster spin than electrons, then this faster spinning quark must be causing this faster gravitational attraction. Strong force containment must be a myth and gravitational force must be caused by a certain quark, probably the down quark.
I told Tom about the harmonic aspect of it all and told him he proved the speed of gravity was right up there with c2, the speed of light squared.
Tom's answer to me was simply, "You cannot square a speed."
Years later I was discussing this with Nobel Laureate Brian Josephson, who showed me the PROOF (below) of Tom Van Flandern's statement.
Try to square the speed of light, taking c that is 3x108 meters per second and squaring it to9x1016mps.
But c is also 3x1010 centimeters per second, and squaring it gives us 9x1020cm.ps which converted back to mps tells us c2 =9x1018mps.
This is far faster that the initial c2.
This is Brian's PROOF that you cannot square a speed!
If you do not believe Brian's proof then find a calculator that works to at least 21 decimal places and square both the speed of light in meters per second and then in miles per second.You will find that the meters per second squared, speed is a far FASTER SPEED than the miles per second squared, SPEED!
I'm writing this speed squared correction to many paper's that I've written years ago: it cannot be a square because one cannot square a speed. So it's best ONLY to say one quark spins at a harmonic of the electron's spin frequency. It must be anextremely high harmonic of the electron if the speed of gravity is more than 20 billion times the speed of light.
And the quark must not only spin but precess at anextremely high harmonic of the electron if both a spin up and spin down electron can encircle it.
A quark spinning at anextremely high harmonic of the electron's spin frequency would only slightly affect the freedom of a free electron BUT that's all it would take because an electron needs 100% freedom to entirely repel other 100% free electrons, because BOTH must have EXACTLY equal precession to keep repelling each other.
I've already explained why this is so in many previous internet papers, such as in the following link.amperefitz.com/darkmtr.htm
So Einstein's c2 is indeed a riddle wrapped inside an enigma that we are still trying to solve, because'you can't quantize without fixing the gauge'. Your math only gives accurate measurements in your spacetime realm or 'your gauge'. Atomic energy (mc2) is being generated within both the quark and electron spacetime realms, neither of which is your spacetime realm.
In the quark spacetime realm, after the Big Bang, iron became the best balanced element.Fission and fusion work on opposite sides of the BALANCE SCALE. Fission builds up the smaller elements into pieces closer to iron and fusion breaks up the larger elements into pieces closer to iron.
Both fission and fusion atomic energy are now slowly re-balancing the quark realm better toward the element iron.
Without this present slight unbalance, neither life nor this array of elements is able to exist.
The establishment misses all this because they would rather believe in old myths than the balance evidence that you can get by clicking those two, previous links.
Given enough time, with fission and fusion energy, this universe will be converted entirely to iron, or elements close enough to it, where no more atomic energyscalar balancing is possible.
Dr. Milo Wolff, one of those NASA scientists that helped get us to the moon, taught me that this is ascalar frequency universe all throughout.
If we are tuned to a frequency close to or at Planck's Constant, then we will only be able to see frequencies higher than us (microcosm) as frequencies.
We will see lower frequencies than us (macrocosm) as something else.
Einstein searched for laws that would unify both micro and macro worlds. However, he failed.
If you read my writings, you will see, that the one thing I've been absolutely certain of — since my first book in 1966 — is that the phase laws, given to us by Andre M. Ampere in the 1820s, are universal laws, good both in the micro and macro worlds, while our present science rules are merely subset rules, that can not be interchanged between the microcosm and macrocosm.
Once you know something like this, that the mob doesn't, then that allows you to solve more science problems than the mob can.
The followingin blue is from my book "Universities Asleep at the Switch" that I published well over a decade ago.
Kurt Gödel proved that if we were confined in a subset realm — like here on earth — without being able to see out far enough then we might believe that our science laws were universal truths when this would be far from the truth. This is exactly what has happened.
Berkeley, then Mach then Maxwell all told us surroundings were involved (Mach's principle). Since this did not mix well with present science and made the math too difficult, it was simply given lip service and largely bypassed and ignored by the universities. The university presses printed, "Inertia is implicit with the geodesic equation of motion." Now, thanks to my good friend Dr. Milo Wolff, we have actual proof inertia is not implicit with the geodesic equation of motion; it's same frequency surroundings that are involved. We have computers, coming on line in the future, that will do these calculations and will give even more proof of this than Milo gave.
Dirac predicted that one day we would be able to see an approximation of how it all worked and how true this becomes. The basic building blocks of this universe are simple standing waves whose spins and orbits produce vector forces, but this fact is totally obscured by all our subset, local science laws and the tons of garbage printed by the university presses.
They do print some diamonds as well but the problem is the same as in a diamond mine where you have to go through many tons of mud to get only one diamond.
The diamond that this book is showing you is that it is surroundings, surroundings, surroundings and spins, spins, spins. It's surroundings and either spin or orbital binding. These spins are spins that bind, giving us not only binding energy but gravity, inertia, light and all the invisible forces as well.
In fact, that's what this book will be explaining.
And that, essentially, is what you should be looking at to get the big picture of how our entire universe works.
Even though we see energy as avector force, we entirely miss the fact that, taking the surroundings into consideration, energy is really an attempt at better overall scalar balancing.
I'm afraid the present science establishment entirely misses this and the supreme importance of Ampere's Laws.
Mathematician Stephen Wolfram hit the nail on the head telling us,"Math can only explain simple things, but a simple model can explain a complicated universe."
I believe we won't even have scratched the surface of science until the establishment realizes the supreme importance of frequencies and phase.
Thesimple phase model that explains our complicated universe is right there in front of our noses, but few see it.
Ampere'ssimple phase model not only shows us exactly how our universe works but it showed me that, while Einstein thought his biggest blunder was the insertion of the factor denoted by the Greek capital letter lambda into his General Relativity formula, his biggest blunder was in removing lambda from General Relativity.
If this paper is still around half a century from now, the people reading it then will see I was right about this.
The removal of lambda,by Einstein himself, strengthened a Phlogiston type myth, that has set us back in science far more than any myth yet.
I've enjoyed this world of science and I've really enjoyed being the sole resident on a completely fenced 600 acre ranch between Dripping Springs and Blanco here in Texas, but even in this area the highway traffic is getting worse, so I handed my son the keys to my car with only 5,000 miles on it and I will enjoy my 85th birthday, in a few weeks, in one of the better retirement places here, near Austin, Texas.
If I kept my car and had an accident and it wasn't my fault, these kids on the jury would say, "You know that old geezer had to cause it!"
Still have my pilot's license that I got in 1950 when I was 17. I loved flying; they were my wings: the instant that I emerged out of a cloud the ground was never level but tilted! WHY?
I saw it was centrifugal force playing tricks on my senses, so I learned about using gyro instruments and took many hours of necessary Link training.
Flew many airplanes, some my own. Never wrecked one but almost killed myself several times. Guess all that flying is over now too.
I knew early that I had to find out EXACTLY how gyroscopes worked. Later in life I worked with the very latest in electronics and gyros, for several decades.
This led me to far more knowledge about our universe, and to finally be able to write this paper to all of you who want to know a bit more about this universe than the present establishment can possibly tell you.
Daniel P. Fitzpatrick Jr.
November 25, 2017
Here's one on June 12th 2018 telling about a Britannica mistake, but half way through is a most interesting dissertation on how our eyes see COLORS.
Britannica in html:
Britannica in Word:http://rbduncan.com/britannica.doc
Britannica in Adobe pdf:http://rbduncan.com/britannica.pdf
See: Phase symmetry makes quantum theory more complete. 12-02-2013
Also read (2005 addendum2017):http://www.rbduncan.com/quarkspin.htm
And read this page:http://www.amperefitz.com/abstract.htm
Here's the link- to this abstract page - in Adobe pdf: http://www.amperefitz.com/abstract.pdf (Click or copy any of these links.)
For 4 Decades of my writings: clickhttp://www.amperefitz.com/4.decades.htm
45 Years of Putting this Jigsaw Puzzle together - of unifying Gravity with all the other forces
45 Years of Putting this Jigsaw Puzzle together - of unifying Gravity with all the other forces" also in Adobe.pdf -45years.pdf
It's all nothing but RELATIVE MOTION !!!.htm
"Ampere showed us, it's all nothing but RELATIVE MOTION !!!(phase)" (science) e-book by Fitzpatrick also in Adobe.pdf - Amp.pdf
Also you can buy my latest book at Amazon or read it FREE using links below:
http://www.amperefitz.com/unvasleep.pdf (This is the book in Adobe)
http://www.amperefitz.com/unvasleep.htm (This book link opens faster if you have dial up.)
There was a full page in the New York Times devoted exclusively about Fitzpatrick's First Book on June 18th 1967.
"Fitzpatrick's First Book" also in Adobe.pdf - pge1.pdf
Click above links to read that first book of mine free.
I've found out and published a lot more since then:Over 4 Decades of Fitzpatrick's Books, Papers & Thoughts in Microsoft "Word":
And here's this page duplicated in Adobe.pdf:http://www.amperefitz.com/4.decades.pdf
Fitzpatrick's website is athttp://www.amperefitz.com
Another older website carrying Fitzpatrick's works FREE is:http://www.rbduncan.com | <urn:uuid:0bdb6bd5-8f67-4efe-a0b2-8943ff53d966> | 3.140625 | 2,887 | Personal Blog | Science & Tech. | 60.922836 | 95,579,280 |
δ18O and δ13C Isotope Analysis of Carbonate Rock
Dry and finely ground carbonate mineral samples and standards are weighed into clean exetainers, which are sealed with rubber septa. The exetainers are loaded in the gas bench at 72°C and all subsequent operations are carried out using the PAL A200S autosampler. Air is removed by replacement with ultrapure helium using the autosampler, then the sample is acidified with 100% phosphoric acid. After an hour the CO2 produced by the reaction is sampled and sent to the mass spectrometer in helium, via a water trap and GC column in the gas bench. Analysis is in continuous flow mode, with CO2 gas of known isotopic composition used as the reference gas. Fractionation is calculated by multiple analyses of internal standards that have been calibrated against international standards NBS 18 and 19.
Carbonate samples should preferably be submitted as powders in a small glass vial (plastic causes static problems). If powdering is not possible, small chips can be sent. Approximately 200 micrograms is analysed of pure carbonates; the weight goes up for samples with low percentage of carbonate content. The submitted samples should be accompanied by a list that includes the percentage of carbonate in the rock, and the (approximate) proportions of carbonate minerals in the case of a mixture (calcite, dolomite, magnesite, hydromagnesite, siderite, ankerite, etc.).
Please ship the samples to Janet Gabites, and also email the list to firstname.lastname@example.org.
Dissolved Inorganic Carbon
DIC is analysed on the gas bench by adding 600 microlitres of the sample water to a clean exetainer sealed with a rubber septum. The exetainer is flushed with helium to replace air in the headspace and to sparge CO2 dissolved in the water. Phosphoric acid is added, the sample is shaken then left to equilibrate for one hour. The CO2 produced is introduced into the mass spectrometer in continuous flow mode.
Non-Traditional Stable Isotopes
A wide range of non-traditional stable isotope systems are currently analysed at PCIGR. For these elements, the natural mass dependent isotopic fractionation is measured; it is therefore crucial to accurately and precisely correct for the instrumental mass fractionation without eradicating this natural signature. Data are also sensitive to both spectral and non-spectral matrix effects (Barling et al, 2006) and thus every effort is made to remove all matrix. Every element system has its own issues in this regard.
Analytical protocols at PCIGR have been set up for Li, Fe, Cu, Zn, Mo and Cd. Where the element of interest is the focus of graduate research, the student, under supervision, is responsible for establishing the protocol for the element. The first step is to establish conditions for precise and accurate measurement of a single standard (i.e. measurement of del = 0). To do this a number of factors are investigated. These include, but are not limited to: length of analysis, need for on-peak-zeros, automatrix effects, optimal analyte element/external normalizing element ratio. After this a secondary standard is introduced to determine that accurate and precise non-zero dels can be measured. Finally, samples are measured. At this point unsuspected matrix effects may be detected due either to a specific element causing a spectral interference or to a high level of matrix causing non-spectral matrix effects. If such matrix effects are detected then sample purification protocols are fine tuned either to eliminate specific elements and/or for specific types of matrix e.g. geological v. biological matrices (Barling et al., 2006, Shiel et al. 2009).
The range of analytical issues covered and the rigour needed in order to establish measurement protocols for analysis of a non-traditional stable isotope system means that once a PCIGR student has done this they are fully capable of applying what they have learned to the isotopic analysis of any other element of interest on the Nu Plasma or indeed on any MC-ICP-MS.
Lithium has no similar mass element that could be used to monitor instrumental mass fractionation externally and only two isotopes. For Li therefore, instrumental mass fractionation can only be compensated for by assuming a stable drift in instrument behaviour and samples are therefore measured by simple sample standard bracketing of measured ratios. The existence of only two isotopes means that Li is vulnerable to unidentified spectral and non-spectral matrix effects since these cannot be identified in the data. However, the low mass of Li means that few elemental and isobaric interferences are present, although 14N2+, 12C2+ can occur (Tomascak, 2004). Non-spectral matrix effects are mitigated by thorough calibration of the Li separation chemistry.
At PCIGR we have adopted the approach of Jeffcoate et al. (2004). Using this method we are currently able to measure d7Li/6Li in samples to within ± 1‰ (2SD).
Li isotope systematics are currently being applied to pegmatite geochemistry (Barnes et al., 2008a, 2008b).
Mo, Cd, Zn isotopes
In contrast to Li, elements like Mo and Cd, have multiple isotopes and a choice of possible elements to use to normalize the data externally for instrumental mass fractionation. For these elements data quality can be assured by agreement of results from different data reduction methods (e.g. simple sample standard bracketing of measured ratios, sample standard bracketing of externally normalized data and graphical data reduction) and by internal consistency of the del/amu of multiple isotope ratios for individual runs. One has therefore several means of identifying spectral and non-spectral matrix effects for these elements.
For Mo and Zn all the necessary isotopes can be measured in a single static cycle, with typical 2SD errors on d/amu that are better than ± 0.05‰. In contrast a dynamic approach, using two cycles is required in order to measure Cd isotopes. This is due to the range of masses measured; from 107Ag (external normalization element) to 118Sn (isobaric interference). The dynamic approach can introduce additional uncertainty to the measurements due to the inherent instability of a plasma source, even so typical 2SD errors on d/amu for two cycle dynamic measurements is better than ± 0.1‰.
Cd, Zn and Pb isotope systematics are currently being applied to the sourcing of metals in bivalves (Shiel et al., 2008).
Fe isotopes present their own special set of difficulties due to major polyatomic interferences inherent to the ICP source: ArN+ (mass 54), ArO+ (mass 56) and ArOH+ (mass 57). A number of approaches can be used to minimize the significance of these interferences, however, they generally rely on increasing the Fe signal relative to the interferences and thus require µg size Fe samples. In order to measure smaller (<300ng) Fe samples at PCIGR we have been investigating various means of reducing argide production and transmission without sacrificing instrument sensitivity for Fe (Aimoz et al., 2008).
Cartoon illustrating parameters investigated by Aimoz et al., 2008.
Radiogenic Isotopes (by MC-ICP-MS)
Nd, Hf and Pb isotope ratios are measured at PCIGR (e.g. Weis et al. 2005, 2006, 2007). Each analysis takes approximately 13 minutes and consumes 100, 75 and 40 ng respectively of Nd, Hf and Pb with regular settings. With the ES interface, the analyte size can be reduced to 25, 20 and 10 ng respectively for Nd, Hf and Pb.
Annual external reproducibility (2SD) for standards are currently: 43 ppm on 143Nd/144Nd, 27 ppm on 176Hf/177Hf and 91 ppm on 206Pb/206Pb. External reproducibility during a single measurement session is better than this by a factor of two or more. (See individual element links below). For sample runs, standards bracket every two samples and data are normalized to these bracketing standards offline. After offline normalization, typical 2SD external reproducibility of replicate samples is better than 40 ppm for 144Nd/143Nd, 70 ppm for 176Hf/177Hf and 200 ppm 206Pb/204Pb.
For Nd isotope ratio measurements, masses 150, 148, 146, 145, 144, 143, 142 are measured together with monitoring of Sm at mass 147 and Ce at mass 140, which allows interference corrections to be applied to masses 150, 148, 144 and 142. Nd isotope measurements are normalized internally for instrumental mass fractionation to a 146Nd/144Nd ratio of 0.7219 using an exponential correction. Interferences on Nd are calculated using natural abundances for the interfering element and adjusting them for instrumental mass fractionation as monitored by the normalizing ratio used to correct the Nd. (Annual values and reproducibility for the JNDI Nd standards in 2014.)
Nd isotopes can be measured by both MC-ICP-MS and TIMS at PCIGR. MC-ICP-MS is usually preferred due to its faster output (~13 min/sample instead of ~1 hour) for similar precision.
The configuration used to measure Hf isotopes enables simultaneous collection of Hf (180, 179, 178, 177, 176 and 174) together with monitoring of Lu at mass 175 and Yb at mass 172, which allows interference corrections to be applied to masses 174 and 176. Hf isotope measurements are normalized internally to a 179Hf/177Hf ratio of 0.7325 using an exponential correction. (Annual values and reproducibility for the JMC Hf standard in 2014.)
For Pb isotopic analyses the instrument is configured for simultaneous collection of Pb (208, 207, 206 and 204) together with Tl (205 and 203), which is used to monitor and correct for instrumental mass discrimination and Hg potential interference (202), which is used to correct mass 204 for the presence of 204Hg. Mercury levels are always below 0.7 mV and more typically are less than 0.2 mV of 202, corresponding to a correction of less than 0.18 (0.05) mV on the 204 peak. To improve the reproducibility of the analytical conditions for the Pb isotopic analyses, and thus the precision, all sample solutions are analyzed with the same Pb/Tl ratios as the NIST SRM 981 standards which requires determination of the exact Pb content after column separation. (Annual values and reproducibility for the NIST SRM 981 standard in 2014.)
A particular concern at PCIGR is that our MC-ICP-MS Pb isotope data achieve the best levels of precision and accuracy required for investigation of isotope systematics in mantle geochemistry (e.g. Weis et al., 2011). We therefore continue to investigate the roles of residual matrix, leaching and sample purification on the ultimate precision and accuracy of MC-ICP-MS Pb data (Barling & Weis 2008, 2012; Hanano et al. 2009; Nobre Silva et al. 2009).
Sr isotopes (by TIMS)
For Sr isotopic analyses, both TIMS instruments are configured for simultaneous collection of Sr Sr (84, 86, 87, 88) and Rb at mass 85, which allows for interference corrections to be applied to 87Sr for the potential presence of 87Rb. Each analysis takes approximately 1 hour. Sr isotope measurements are normalized internally to an 86Sr/88Sr ratio of 0.1194 using an exponential correction. For sample runs, data are normalized to the average value of the standard SRM NBS 987 (typically 3-4 standards analysed for 17-18 samples). | <urn:uuid:42b4112a-4cf6-4249-8092-dd88785bb2a2> | 2.53125 | 2,545 | Documentation | Science & Tech. | 42.371889 | 95,579,284 |
Authors: George Rajna
A team led by the Department of Energy's Oak Ridge National Laboratory has used sophisticated neutron scattering techniques to detect an elusive quantum state known as the Higgs amplitude mode in a two-dimensional material. The magnetic induction creates a negative electric field, causing an electromagnetic inertia responsible for the relativistic mass change; it is the mysterious Higgs Field giving mass to the particles. The Planck Distribution Law of the electromagnetic oscillators explains the electron/proton mass rate by the diffraction patterns. The accelerating charges explain not only the Maxwell Equations and the Special Relativity, but the Heisenberg Uncertainty Relation, the wave particle duality and the electron's spin also, building the bridge between the Classical and Relativistic Quantum Theories. The self maintained electric potential of the accelerating charges equivalent with the General Relativity space-time curvature, and since it is true on the quantum level also, gives the base of the Quantum Gravity. The diffraction patterns and the locality of the self-maintaining electromagnetic potential explains also the Quantum Entanglement, giving it as a natural part of the relativistic quantum theory.
Comments: 10 Pages.
[v1] 2017-07-06 01:25:12
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New species of fish found in one of the deepest places on Earth - almost 4.5 miles beneath the sea
A new species has been discovered in a part of the ocean previously thought to be entirely free of fish, scientists said today.
The new type of snailfish was found living at a depth of 22,966ft in the Peru-Chile trench of the South East Pacific Ocean.
Mass groupings of cusk-eels and large crustacean scavengers were also discovered living at these depths for the first time, scientists said.
The findings, in one of the deepest places on the planet, were made by a team of marine biologists from the University of Aberdeen and experts from Japan and New Zealand.
The new species of snail fish discovered living more than four miles under the sea
The team took part in a three-week expedition, during which they used deep-sea imaging technology to take 6,000 pictures at depths between 14,764ft and 26,247ft within the trench.
The mission was the seventh to take place as part of HADEEP, a collaborative research project
The fish was found in the trench off the coast of Peru and Chile
between the University of Aberdeen's Oceanlab and the University of Tokyo's Ocean Research Institute, supported by New Zealand's National Institute of Water and Atmospheric research (NIWA).
The University of Aberdeen said these latest discoveries helped shed new light on life in the depths of the Earth.
Oceanlab's Dr Alan Jamieson, who led the expedition, said: 'Our findings, which revealed diverse and abundant species at depths previously thought to be void of fish, will prompt a rethink into marine populations at extreme depths.
'This expedition was prompted by our findings in 2008 and 2009 off Japan and New Zealand where we discovered new species of snailfish known as Liparids inhabiting trenches... at depths of approximately 7,000 metres - with each trench hosting its own unique species of the fish.
'To test whether these species would be found in all trenches, we repeated our experiments on the other side of the Pacific Ocean off Peru and Chile, some 6,000 miles (9,656km) from our last observations.
The discovery could mean that there
are thousands more unknown fish in hidden depths in the world's ocean.
Dr Jamieson said: 'What we found was that indeed there was another unique species of snailfish living at 7,000 metres - entirely new to science - which had never been caught or seen before.
'A species of cusk-eel - known as Ophidiids - also gathered at our camera and began a feeding frenzy that lasted 22 hours - the entire duration of the deployment.
Cusk eels discovered living 6000 metres under the sea. Scientists had thought that the pitch black and freezing conditions were too harsh to sustain life
'Further research needs to be conducted to decipher whether this is also an entirely new species of cusk-eel that we have discovered.
'Our investigations also revealed a species of crustacean scavengers - known as amphipods - which we previously did not know existed at these depths in such great numbers.
'These are large shrimp-like creatures of which one particular group, called Eurythenes, were generally far larger and occurred much deeper in this trench than has ever been found before.'
Dr Toyonobu Fujii, a deep-sea fish expert from Aberdeen University, added: 'How deep fish can live has long been an intriguing question and the results from this expedition has provided deeper insight into our understanding of the global distribution of fish in the oceans.'
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The findings suggest that the role of tropical forests in offsetting the atmospheric buildup of carbon from fossil fuels depends on tree diversity, particularly in forests recovering from exploitation.
Tropical forests thrive on natural nitrogen fertilizer pumped into the soil by trees in the legume family, a diverse group that includes beans and peas, the researchers report in the journal Nature. The researchers studied second-growth forests in Panama that had been used for agriculture five to 300 years ago.
The presence of legume trees ensured rapid forest growth in the first 12 years of recovery and thus a substantial carbon "sink," or carbon-storage capacity. Tracts of land that were pasture only 12 years before had already accumulated as much as 40 percent of the carbon found in fully mature forests. Legumes contributed more than half of the nitrogen needed to make that happen, the researchers reported.
These fledgling woodlands had the capacity to store 50 metric tons of carbon per hectare (2.47 acres), which equates to roughly 185 tons of carbon dioxide, or the exhaust of some 21,285 gallons of gasoline. That much fuel would take the average car in the United States more than half a million miles. Though the legumes' nitrogen fertilizer output waned in later years, the species nonetheless took up carbon at rates that were up to nine times faster than non-legume trees.The legumes' secret is a process known as nitrogen fixation, carried out in concert with infectious bacteria known as rhizobia, which dwell in little pods inside the tree's roots known as root nodules. As a nutrient, nitrogen is essential for plant growth, but tropical soil is short on nitrogen and surprisingly non-nutritious for trees. Legumes use secretions to invite rhizobia living in the soil to infect their roots, and the bacteria signal back to initiate nodule growth. The rhizobia move into the root cells of the host plant and — in exchange for carbohydrates the tree produces by photosynthesis — convert nitrogen in the air into the fertilizer form that plants need. Excess nitrogen from the legume eventually creates a nitrogen cycle that benefits neighboring trees.
"Tropical forests are a huge carbon sink. If trees could just grow and store carbon, you could have a rapid sink, but if they don't have enough nitrogen they don't take up carbon," said Hedin, adding that nitrogen-fixing trees are uncommon in temperate forests such as those in most of North America and Europe.
"Legumes are a group of plants that perform a valuable function, but no one knew how much they help with the carbon sink," Hedin said. "This work shows that they may be critical for the carbon sink, and that the level of biodiversity in a tropical forest may determine the size of the carbon sink."
First author Sarah Batterman, a postdoctoral research associate in Hedin's research group, said legumes, or nitrogen fixers, are especially important for forests recovering from agricultural use, logging, fire or other human activities. The researchers studied 16 forest plots that were formerly pasture and are maintained by the Smithsonian Tropical Research Institute (STRI).
Forest degradation, however, comes with a loss of biodiversity that can affect nitrogen fixers, too, even though legumes are not specifically coveted or threatened, Batterman said. If the numbers and diversity of nitrogen fixers plummet then the health of the surrounding forest would likely be affected for a very long time.
"This study is showing that there is an important place for nitrogen fixation in these disturbed areas," Batterman said. "Nitrogen fixers are a component of biodiversity and they're really important for the function of these forests, but we do not know enough about how this valuable group of trees influences forests. While some species may thrive on disturbance, others are in older forests where they may be sensitive to human activities."
The researchers found that the nine legume species they studied did not contribute nitrogen to surrounding trees at the same time. Certain species were more active in the youngest forests, others in middle-aged forests, and still other species went into action mainly in 300-year-old tracts, though not nearly to the same extent as legumes in younger plots. The researchers found that individual trees reduced their fixation as nitrogen accumulated in soils, with the number of legumes actively fixing nitrogen dropping from 71 to 23 percent between 12- and 80-year-old forests.
"In that way, the diversity of species that are present in the forest is really critical because it ensures that there can be fixation at all different time periods of forest recovery whenever it's necessary," Batterman said. "If you were to lose one of those species and it turned out to be essential for a specific time period, fixation might drop dramatically."
Such details can improve what scientists know about future climate change, Batterman said. Computer models that calculate the global balance of atmospheric carbon dioxide also must factor in sinks that offset carbon, such as tropical forests. And if forests take up carbon differently depending on the abundance and diversity of legumes, models should reflect that variation, she said. Batterman is currently working with Princeton Assistant Professor of Geosciences David Medvigy on a method for considering nitrogen fixation in models.
"This finding is really important because other researchers can now go and put this role of nitrogen fixation into their models and improve predictions about the carbon sink," Batterman said.
Batterman and Hedin worked with Michiel van Breugel, an STRI postdoctoral fellow; Johannes Ransijn, a University of Copenhagen doctoral student in geosciences and natural-resource management; Dylan Craven, a Yale University doctoral candidate in forestry and environmental studies; and Jefferson Hall, an STRI staff scientist and leader of the institute's Agua Salud Project that maintains and studies the plots the researchers examined.
The paper, "Key role of symbiotic N2 fixation in tropical forest secondary succession," was published online Sept. 15 by the journal Nature. The work was supported by grants from the National Science Foundation (grant number DEB-0614116), the National Oceanic and Atmospheric Administration (grant number NA17RJ262 – 344), the Smithsonian Tropical Research Institute, and the Cooperative Institute for Climate Science and the Carbon Mitigation Initiative, both at Princeton University.
Morgan Kelly | EurekAlert!
Further reports about: > Batterman > Légumes > Nature Immunology > Princeton > STRI > Science TV > Smithsonian > Tropical Research > atmospheric carbon > atmospheric carbon dioxide > carbon dioxide > human activities > nitrogen fertilizer > nitrogen fixation > nitrogen fixers > tropical diseases > tropical forest
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Quantum field theory(Redirected from Quantum field theories)
In theoretical physics, quantum field theory (QFT) is the theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics. It is a set of notions and mathematical tools that combines classical fields, special relativity, and quantum mechanics,. When combined with the cluster decomposition principle, it may be the only way to do so, while retaining the ideas of quantum point particles and locality. QFT was previously believed to be truly fundamental; however, it is now believed, primarily because of the continued failures of quantization of general relativity, to be only a very good low-energy approximation, i.e. an effective field theory, to a more fundamental theory.
QFT treats particles as excited states of an underlying field, so these are called field quanta. In quantum field theory, quantum mechanical interactions among particles are described by interaction terms among the corresponding underlying quantum fields. These interactions are conveniently visualized by Feynman diagrams, which are a formal tool of relativistically covariant perturbation theory, serving to evaluate particle processes.
Even though QFT is an unavoidable consequence of the reconciliation of quantum mechanics with special relativity (Weinberg (1995)), historically, it emerged in the 1920s with the quantization of the electromagnetic field (the quantization being based on an analogy with the eigenmode expansion of a vibrating string with fixed endpoints).
The first achievement of quantum field theory, namely quantum electrodynamics (QED), is "still the paradigmatic example of a successful quantum field theory" (Weinberg (1995)). Ordinary quantum mechanics (QM) cannot give an account of photons, which constitute the prime case of relativistic 'particles'. Since photons have rest mass zero, and correspondingly travel in the vacuum at the speed c, a non-relativistic theory such as ordinary QM cannot give even an approximate description. Photons are implicit in the emission and absorption processes which have to be postulated, for instance, when one of an atom's electrons makes a transition between energy levels. The formalism of QFT is needed for an explicit description of photons. In fact most topics in the early development of quantum theory (the so-called old quantum theory, 1900–25) were related to the interaction of radiation and matter and thus should be treated by quantum field theoretical methods. However, quantum mechanics as formulated by Dirac, Heisenberg, and Schrödinger in 1926–27 started from atomic spectra and did not focus much on problems of radiation.
As soon as the conceptual framework of quantum mechanics was developed, a small group of theoreticians tried to extend quantum methods to electromagnetic fields. A good example is the famous paper by Born, Jordan & Heisenberg (1926). (P. Jordan was especially acquainted with the literature on light quanta and made seminal contributions to QFT.) The basic idea was that in QFT the electromagnetic field should be represented by matrices in the same way that position and momentum were represented in QM by matrices (matrix mechanics oscillator operators). The ideas of QM were thus extended to systems having an infinite number of degrees of freedom, so an infinite array of quantum oscillators.
The inception of QFT is usually considered to be Dirac's famous 1927 paper on "The quantum theory of the emission and absorption of radiation". Here Dirac coined the name "quantum electrodynamics" (QED) for the part of QFT that was developed first. Dirac supplied a systematic procedure for transferring the characteristic quantum phenomenon of discreteness of physical quantities from the quantum-mechanical treatment of particles to a corresponding treatment of fields. Employing the theory of the quantum harmonic oscillator, Dirac gave a theoretical description of how photons appear in the quantization of the electromagnetic radiation field. Later, Dirac's procedure became a model for the quantization of other fields as well. These first approaches to QFT were further developed during the following three years. P. Jordan introduced creation and annihilation operators for fields obeying Fermi–Dirac statistics. These differ from the corresponding operators for Bose–Einstein statistics in that the former satisfy anti-commutation relations while the latter satisfy commutation relations.
The methods of QFT could be applied to derive equations resulting from the quantum-mechanical (field-like) treatment of particles, e.g. the Dirac equation, the Klein–Gordon equation and the Maxwell equations. Schweber points out that the idea and procedure of second quantization goes back to Jordan, in a number of papers from 1927, while the expression itself was coined by Dirac. Some difficult problems concerning commutation relations, statistics, and Lorentz invariance were eventually solved. The first comprehensive account of a general theory of quantum fields, in particular, the method of canonical quantization, was presented by Heisenberg & Pauli in 1929–30. Whereas Jordan's second quantization procedure applied to the coefficients of the normal modes of the field, Heisenberg & Pauli started with the fields themselves and subjected them to the canonical procedure. Heisenberg and Pauli thus established the basic structure of QFT as presented in modern introductions to QFT. Fermi and Dirac, as well as Fock and Podolsky, presented different formulations which played a heuristic role in the following years.
Quantum electrodynamics rests on two pillars, see e.g., the short and lucid "Historical Introduction" of Scharf (2014). The first pillar is the quantization of the electromagnetic field, i.e., it is about photons as the quantized excitations or 'quanta' of the electromagnetic field. This procedure will be described in some more detail in the section on the particle interpretation. As Weinberg points out the "photon is the only particle that was known as a field before it was detected as a particle" so that it is natural that QED began with the analysis of the radiation field. The second pillar of QED consists of the relativistic theory of the electron, centered on the Dirac equation.
The problem of infinitiesEdit
The emergence of infinitiesEdit
Quantum field theory started with a theoretical framework that was built in analogy to quantum mechanics. Although there was no unique and fully developed theory, quantum field theoretical tools could be applied to concrete processes. Examples are the scattering of radiation by free electrons, Compton scattering, the collision between relativistic electrons or the production of electron-positron pairs by photons. Calculations to the first order of approximation were quite successful, but most people working in the field thought that QFT still had to undergo a major change. On the one side, some calculations of effects for cosmic rays clearly differed from measurements. On the other side and, from a theoretical point of view more threatening, calculations of higher orders of the perturbation series led to infinite results. The self-energy of the electron as well as vacuum fluctuations of the electromagnetic field seemed to be infinite. The perturbation expansions did not converge to a finite sum and even most individual terms were divergent.
The various forms of infinities suggested that the divergences were more than failures of specific calculations. Many physicists tried to avoid the divergences by formal tricks (truncating the integrals at some value of momentum, or even ignoring infinite terms) but such rules were not reliable, violated the requirements of relativity and were not considered as satisfactory. Others came up with the first ideas for coping with infinities by a redefinition of the parameters of the theory and using a measured finite value, for example of the charge of the electron, instead of the infinite 'bare' value. This process is called renormalization.
From the point of view of the philosophy of science, it is remarkable that these divergences did not give enough reason to discard the theory. The years from 1930 to the beginning of World War II were characterized by a variety of attitudes towards QFT. Some physicists tried to circumvent the infinities by more-or-less arbitrary prescriptions, others worked on transformations and improvements of the theoretical framework. Most of the theoreticians believed that QED would break down at high energies. There was also a considerable number of proposals in favor of alternative approaches. These proposals included changes in the basic concepts e.g. negative probabilities and interactions at a distance instead of a field theoretical approach, and a methodological change to phenomenological methods that focuses on relations between observable quantities without an analysis of the microphysical details of the interaction, the so-called S-matrix theory where the basic elements are amplitudes for various scattering processes.
Despite the feeling that QFT was imperfect and lacking rigor, its methods were extended to new areas of applications. In 1933 Fermi's theory of the beta decay started with conceptions describing the emission and absorption of photons, transferred them to beta radiation and analyzed the creation and annihilation of electrons and neutrinos described by the weak interaction. Further applications of QFT outside of quantum electrodynamics succeeded in nuclear physics with the strong interaction. In 1934 Pauli & Weisskopf showed that a new type of field, the scalar field, described by the Klein–Gordon equation, could be quantized. This is another example of second quantization. This new theory for matter fields could be applied a decade later when new particles, pions, were detected.
The taming of infinitiesEdit
After the end of World War II more reliable and effective methods for dealing with infinities in QFT were developed, namely coherent and systematic rules for performing relativistic field theoretical calculations, and a general renormalization theory. At three famous conferences, the Shelter Island Conference 1947, the Pocono Conference 1948, and the 1949 Oldstone Conference, developments in theoretical physics were confronted with relevant new experimental results. In the late forties, there were two different ways to address the problem of divergences. One of these was discovered by Richard Feynman, the other one (based on an operator formalism) by Julian Schwinger and, independently, by Shin'ichirō Tomonaga.
In 1949, Freeman Dyson showed that the two approaches are in fact equivalent and fit into an elegant field-theoretic framework. Thus, Freeman Dyson, Feynman, Schwinger, and Tomonaga became the inventors of renormalization theory. The most spectacular successes of renormalization theory were the calculations of the anomalous magnetic moment of the electron and the Lamb shift in the spectrum of hydrogen. These successes were so outstanding because the theoretical results were in better agreement with high-precision experiments than anything in physics encountered before. Nevertheless, mathematical problems lingered on and prompted a search for rigorous formulations (discussed below).
The rationale behind renormalization is to avoid divergences that appear in physical predictions by shifting them into a part of the theory where they do not influence empirical statements. Dyson could show that a rescaling of charge and mass ('renormalization') is sufficient to remove all divergences in QED consistently, to all orders of perturbation theory. A QFT is called renormalizable if all infinities can be absorbed into a redefinition of a finite number of coupling constants and masses. A consequence for QED is that the physical charge and mass of the electron must be measured and cannot be computed from first principles.
Perturbation theory yields well-defined predictions only in renormalizable quantum field theories; luckily, QED, the first fully developed QFT, belonged to this class of renormalizable theories. There are various technical procedures to renormalize a theory. One way is to cut off the integrals in the calculations at a certain value Λ of the momentum which is large but finite. This cut-off procedure is successful if, after taking the limit Λ → ∞, the resulting quantities are independent of Λ.
Feynman's formulation of QED is of special interest from a philosophical point of view. His so-called space-time approach is visualized by the celebrated Feynman diagrams that look like depicting paths of particles. Feynman's method of calculating scattering amplitudes is based on the functional integral formulation of field theory. A set of graphical rules can be derived so that the probability of a specific scattering process can be calculated by drawing a diagram of that process and then using that diagram to write down the precise mathematical expressions for calculating its amplitude in relativistically covariant perturbation theory.
The diagrams provide an effective way to organize and visualize the various terms in the perturbation series, and they naturally account for the flow of electrons and photons during the scattering process. External lines in the diagrams represent incoming and outgoing particles, internal lines are connected with virtual particles and vertices with interactions. Each of these graphical elements is associated with mathematical expressions that contribute to the amplitude of the respective process. The diagrams are part of Feynman's very efficient and elegant algorithm for computing the probability of scattering processes.
The idea of particles traveling from one point to another was heuristically useful in constructing the theory. This heuristic, based on Huygens' principle, is useful for concrete calculations and actually gives the correct particle propagators as derived more rigorously.
Regardless of heuristic merit, an analysis of the theoretical justification of the space-time approach shows that its success does not imply that particle paths need be taken literally. General arguments against a particle interpretation of QFT clearly reject the idea that the diagrams in the interaction area represent actual paths of particles. Feynman himself, however, had little interest for questions of ontology.
The golden age: gauge theory and the standard modelEdit
In 1933, Enrico Fermi had already established that the creation, annihilation and transmutation of particles in the weak interaction beta decay could best be described in QFT, specifically his quartic fermion interaction. As a result, field theory had become a prospective tool for other particle interactions. In the beginning of the 1950s, QED had become a reliable theory which no longer counted as preliminary. However, it took two decades from writing down the first equations until QFT could be applied successfully to important physical problems in a systematic way.
The theories explored relied on—indeed, were virtually fully specified by—a rich variety of symmetries pioneered and articulated by Murray Gell-Mann. The new developments made it possible to apply QFT to new particles and new interactions and fully explain their structure.
In the following decades, QFT was extended to well-describe not only the electromagnetic force but also weak and strong interaction so that new Lagrangians were found which contain new classes of particles or quantum fields. The search still continues for a more comprehensive theory of matter and energy, a unified theory of all interactions.
The new focus on symmetry led to the triumph of non-Abelian gauge theories (the development of such theories was pioneered in 1954–60 with the work of Yang and Mills; see Yang–Mills theory) and spontaneous symmetry breaking (by Yoichiro Nambu). Today, there are reliable theories of the strong, weak, and electromagnetic interactions of elementary particles which have an analogous structure to QED: They are the dominant framework of particle physics.
A combined renormalizable theory associated with the gauge group SU(3) × SU(2) × U(1) is dubbed the standard model of elementary particle physics (even though it is a full theory, and not just a model) and was assembled by Sheldon Glashow, Steven Weinberg and Abdus Salam in 1959–67 (see Electroweak unification), and Frank Wilczek, David Gross and David Politzer in 1973 (see Asymptotic freedom), on the basis of conceptual breakthroughs by Peter Higgs, François Englert, Robert Brout, Martin Veltman, and Gerard 't Hooft.
According to the standard model, there are, on the one hand, six types of leptons (e.g. the electron and its neutrino) and six types of quarks, where the members of both groups are all fermions with spin 1/2. On the other hand, there are spin 1 particles (thus bosons) that mediate the interaction between elementary particles and the fundamental forces, namely the photon for electromagnetic interaction, two W and one Z-boson for weak interaction, and the gluons for strong interaction. The linchpin of the symmetry breaking mechanism of the theory is the spin 0 Higgs boson, discovered 40 years after its prediction.
Parallel breakthroughs in the understanding of phase transitions in condensed matter physics led to novel insights based on the renormalization group. They emerged in the work of Leo Kadanoff (1966) and Kenneth Geddes Wilson & Michael Fisher (1972)—extending the work of Ernst Stueckelberg–André Petermann (1953) and Murray Gell-Mann–Francis Low (1954)—which led to the seminal reformulation of quantum field theory by Kenneth Geddes Wilson in 1975. This reformulation provided insights into the evolution of effective field theories with scale, which classified all field theories, renormalizable or not (cf. subsequent section). The remarkable conclusion is that, in general, most observables are "irrelevant", i.e., the macroscopic physics is dominated by only a few observables in most systems.
During the same period, Kadanoff (1969) introduced an operator algebra formalism for the two-dimensional Ising model, a widely studied mathematical model of ferromagnetism in statistical physics. This development suggested that quantum field theory describes its scaling limit. Later, there developed the idea that a finite number of generating operators could represent all the correlation functions of the Ising model.
Conformal field theoryEdit
The existence of a much stronger symmetry for the scaling limit of two-dimensional critical systems was suggested by Alexander Belavin, Alexander Polyakov and Alexander Zamolodchikov in 1984, which eventually led to the development of conformal field theory, a special case of quantum field theory, which is presently utilized in different areas of particle physics and condensed matter physics.
Varieties of approachesEdit
Most theories in standard particle physics are formulated as relativistic quantum field theories, such as QED, QCD, and the Standard Model. QED, the quantum field-theoretic description of the electromagnetic field, approximately reproduces Maxwell's theory of electrodynamics in the low-energy limit, with small non-linear corrections to the Maxwell equations required due to virtual electron–positron pairs.
Perturbative and non-perturbative approachesEdit
In the perturbative approach to quantum field theory, the full field interaction terms are approximated as a perturbative expansion in the number of particles involved. Each term in the expansion can be thought of as forces between particles being mediated by other particles. In QED, the electromagnetic force between two electrons is caused by an exchange of photons. Similarly, intermediate vector bosons mediate the weak force and gluons mediate the strong force in QCD. The notion of a force-mediating particle comes from perturbation theory, and does not make sense in the context of non-perturbative approaches to QFT, such as with bound states.
QFT and gravityEdit
There is currently no complete quantum theory of the remaining fundamental force, gravity. Many of the proposed theories to describe gravity as a QFT postulate the existence of a graviton particle that mediates the gravitational force. Presumably, the as yet unknown correct quantum field-theoretic treatment of the gravitational field will behave like Einstein's general theory of relativity in the low-energy limit. Quantum field theory of the fundamental forces itself has been postulated to be the low-energy effective field theory limit of a more fundamental theory such as superstring theory.
Quantum electrodynamics (QED) has one electron field and one photon field; quantum chromodynamics (QCD) has one field for each type of quark; and, in condensed matter, there is an atomic displacement field that gives rise to phonon particles. Edward Witten describes QFT as "by far" the most difficult theory in modern physics – "so difficult that nobody fully believed it for 25 years."
Ordinary quantum mechanical systems have a fixed number of particles, with each particle having a finite number of degrees of freedom. In contrast, the excited states of a quantum field can represent any number of particles. This makes quantum field theories especially useful for describing systems where the particle count/number may change over time, a crucial feature of relativistic dynamics. A QFT is thus an organized infinite array of oscillators.
QFT interaction terms are similar in spirit to those between charges with electric and magnetic fields in Maxwell's equations. However, unlike the classical fields of Maxwell's theory, fields in QFT generally exist in quantum superpositions of states and are subject to the laws of quantum mechanics.
Because the fields are continuous quantities over space, there exist excited states with arbitrarily large numbers of particles in them, providing QFT systems with effectively an infinite number of degrees of freedom. Infinite degrees of freedom can easily lead to divergences of calculated quantities (e.g., the quantities become infinite). Techniques such as renormalization of QFT parameters or discretization of spacetime, as in lattice QCD, are often used to avoid such infinities so as to yield physically plausible results.
Fields and radiationEdit
The gravitational field and the electromagnetic field are the only two fundamental fields in nature that have infinite range and a corresponding classical low-energy limit, which greatly diminishes and hides their "particle-like" excitations. Albert Einstein in 1905, attributed "particle-like" and discrete exchanges of momenta and energy, characteristic of "field quanta", to the electromagnetic field. Originally, his principal motivation was to explain the thermodynamics of radiation. Although the photoelectric effect and Compton scattering strongly suggest the existence of the photon, it might alternatively be explained by a mere quantization of emission; more definitive evidence of the quantum nature of radiation is now taken up into modern quantum optics as in the antibunching effect.
Classical and quantum fieldsEdit
A classical field is a function defined over some region of space and duration in time. Two physical phenomena which are described by classical fields are Newtonian gravitation, described by Newtonian gravitational field g(x, t), and classical electromagnetism, described by the electric and magnetic fields E(x, t) and B(x, t). Because such fields can in principle take on distinct values at each point in space, they are said to have infinite degrees of freedom.
Classical field theory does not, however, account for the quantum-mechanical aspects of such physical phenomena. For instance, it is known from quantum mechanics that certain aspects of electromagnetism involve discrete particles—photons—rather than continuous fields. The business of quantum field theory is to write down a field that is, like a classical field, a function defined over space and time, but which also accommodates the observations of quantum mechanics. This is a quantum field.
To write down such a quantum field, one promotes the infinity of classical oscillators representing the modes of the classical fields to quantum harmonic oscillators. They thus become operator-valued functions (actually, distributions). (In its most general formulation, quantum mechanics is a theory of abstract operators (observables) acting on an abstract state space (Hilbert space), where the observables represent physically observable quantities and the state space represents the possible states of the system under study. For instance, the fundamental observables associated with the motion of a single quantum mechanical particle are the position and momentum operators and . Field theory, by sharp contrast, treats x as a label, an index of the field rather than as an operator.)
Quantum field theory relies on the Lagrangian formalism from classical field theory. This formalism is analogous to the Lagrangian formalism used in classical mechanics to solve for the motion of a particle under the influence of a field. In classical field theory, one writes down a Lagrangian density, , involving a field, φ(x,t), and possibly its first derivatives (∂φ/∂t and ∇φ), and then applies a field-theoretic form of the Euler–Lagrange equation. Writing coordinates (t, x) = (x0, x1, x2, x3) = xμ, this form of the Euler–Lagrange equation is
where a sum over μ is performed according to the rules of Einstein notation.
By solving this equation, one arrives at the "equations of motion" of the field. For example, if one begins with the Lagrangian density
and then applies the Euler–Lagrange equation, one obtains the equation of motion
This equation is Newton's law of universal gravitation, expressed in differential form in terms of the gravitational potential φ(t, x) and the mass density ρ(t, x). Despite the nomenclature, the "field" under study is the gravitational potential, φ, rather than the gravitational field, g. Similarly, when classical field theory is used to study electromagnetism, the "field" of interest is the electromagnetic four-potential (V/c, A), rather than the electric and magnetic fields E and B.
Quantum field theory uses this same Lagrangian procedure to determine the equations of motion for quantum fields. These equations of motion are then supplemented by commutation relations derived from the canonical quantization procedure described below, thereby incorporating quantum mechanical effects into the behavior of the field.
Single- and many-particle quantum mechanicsEdit
Here m is the particle's mass and V(x) is the applied potential. Physical information about the behavior of the particle is extracted from the wavefunction by constructing expected values for various quantities; for example, the expected value of the particle's position is given by integrating ψ*(x) x ψ(x) over all space, and the expected value of the particle's momentum is found by integrating −iħψ*(x)dψ/dx. The quantity ψ*(x)ψ(x) is itself in the Copenhagen interpretation of quantum mechanics interpreted as a probability density function. This treatment of quantum mechanics, where a particle's wavefunction evolves against a classical background potential V(x), is sometimes called first quantization.
This description of quantum mechanics can be extended to describe the behavior of multiple particles, so long as the number and the type of particles remain fixed. The particles are described by a wavefunction ψ(x1, x2, …, xN, t), which is governed by an extended version of the Schrödinger equation.
Often one is interested in the case where N particles are all of the same type (for example, the 18 electrons orbiting a neutral argon nucleus). As described in the article on identical particles, this implies that the state of the entire system must be either symmetric (bosons) or antisymmetric (fermions) when the coordinates of its constituent particles are exchanged. This is achieved by using a Slater determinant as the wavefunction of a fermionic system (and a Slater permanent for a bosonic system), which is equivalent to an element of the symmetric or antisymmetric subspace of a tensor product.
For example, the general quantum state of a system of N bosons is written as
where are the single-particle states, Nj is the number of particles occupying state j, and the sum is taken over all possible permutations p acting on N elements. In general, this is a sum of N! (N factorial) distinct terms. is a normalizing factor.
There are several shortcomings to the above description of quantum mechanics, which are addressed by quantum field theory. First, it is unclear how to extend quantum mechanics to include the effects of special relativity. Attempted replacements for the Schrödinger equation, such as the Klein–Gordon equation or the Dirac equation, have many unsatisfactory qualities; for instance, they possess energy eigenvalues that extend to –∞, so that there seems to be no easy definition of a ground state. It turns out that such inconsistencies arise from relativistic wavefunctions not having a well-defined probabilistic interpretation in position space, as probability conservation is not a relativistically covariant concept. The second shortcoming, related to the first, is that in quantum mechanics there is no mechanism to describe particle creation and annihilation; this is crucial for describing phenomena such as pair production, which result from the conversion between mass and energy according to the relativistic relation E = mc2.
In this section, we will describe a method for constructing a quantum field theory called second quantization. This basically involves choosing a way to index the quantum mechanical degrees of freedom in the space of multiple identical-particle states. It is based on the Hamiltonian formulation of quantum mechanics.
For simplicity, we will first discuss second quantization for bosons, which form perfectly symmetric quantum states. Let us denote the mutually orthogonal single-particle states which are possible in the system by and so on. For example, the 3-particle state with one particle in state and two in state is
The first step in second quantization is to express such quantum states in terms of occupation numbers, by listing the number of particles occupying each of the single-particle states etc. This is simply another way of labelling the states. For instance, the above 3-particle state is denoted as
An N-particle state belongs to a space of states describing systems of N particles. The next step is to combine the individual N-particle state spaces into an extended state space, known as Fock space, which can describe systems of any number of particles. This is composed of the state space of a system with no particles (the so-called vacuum state, written as ), plus the state space of a 1-particle system, plus the state space of a 2-particle system, and so forth. States describing a definite number of particles are known as Fock states: a general element of Fock space will be a linear combination of Fock states. There is a one-to-one correspondence between the occupation number representation and valid boson states in the Fock space.
At this point, the quantum mechanical system has become a quantum field in the sense we described above. The field's elementary degrees of freedom are the occupation numbers, and each occupation number is indexed by a number indicating which of the single-particle states it refers to:
The properties of this quantum field can be explored by defining creation and annihilation operators, which add and subtract particles. They are analogous to ladder operators in the quantum harmonic oscillator problem, which added and subtracted energy quanta. However, these operators literally create and annihilate particles of a given quantum state. The bosonic annihilation operator and creation operator are easily defined in the occupation number representation as having the following effects:
It can be shown that these are operators in the usual quantum mechanical sense, i.e. linear operators acting on the Fock space. Furthermore, they are indeed Hermitian conjugates, which justifies the way we have written them. They can be shown to obey the commutation relation
where stands for the Kronecker delta. These are precisely the relations obeyed by the ladder operators for an infinite set of independent quantum harmonic oscillators, one for each single-particle state. Adding or removing bosons from each state is, therefore, analogous to exciting or de-exciting a quantum of energy in a harmonic oscillator.
Applying an annihilation operator followed by its corresponding creation operator returns the number of particles in the kth single-particle eigenstate:
The combination of operators is known as the number operator for the kth eigenstate.
The Hamiltonian operator of the quantum field (which, through the Schrödinger equation, determines its dynamics) can be written in terms of creation and annihilation operators. For instance, for a field of free (non-interacting) bosons, the total energy of the field is found by summing the energies of the bosons in each energy eigenstate. If the kth single-particle energy eigenstate has energy and there are bosons in this state, then the total energy of these bosons is . The energy in the entire field is then a sum over :
This can be turned into the Hamiltonian operator of the field by replacing with the corresponding number operator, . This yields
It turns out that a different definition of creation and annihilation must be used for describing fermions. According to the Pauli exclusion principle, fermions cannot share quantum states, so their occupation numbers Ni can only take on the value 0 or 1. The fermionic annihilation operators c and creation operators are defined by their actions on a Fock state thus
These obey an anticommutation relation:
One may notice from this that applying a fermionic creation operator twice gives zero, so it is impossible for the particles to share single-particle states, in accordance with the exclusion principle.
We have previously mentioned that there can be more than one way of indexing the degrees of freedom in a quantum field. Second quantization indexes the field by enumerating the single-particle quantum states. However, as we have discussed, it is more natural to think about a "field", such as the electromagnetic field, as a set of degrees of freedom indexed by position.
To this end, we can define field operators that create or destroy a particle at a particular point in space. In particle physics, these operators turn out to be more convenient to work with, because they make it easier to formulate theories that satisfy the demands of relativity.
Single-particle states are usually enumerated in terms of their momenta (as in the particle in a box problem.) We can construct field operators by applying the Fourier transform to the creation and annihilation operators for these states. For example, the bosonic field annihilation operator is
The bosonic field operators obey the commutation relation
where stands for the Dirac delta function. As before, the fermionic relations are the same, with the commutators replaced by anticommutators.
The field operator is not the same thing as a single-particle wavefunction. The former is an operator acting on the Fock space, and the latter is a quantum-mechanical amplitude for finding a particle in some position. However, they are closely related and are indeed commonly denoted with the same symbol. If we have a Hamiltonian with a space representation, say
where the indices i and j run over all particles, then the field theory Hamiltonian (in the non-relativistic limit and for negligible self-interactions) is
This looks remarkably like an expression for the expectation value of the energy, with playing the role of the wavefunction. This relationship between the field operators and wave functions makes it very easy to formulate field theories starting from space projected Hamiltonians.
Once the Hamiltonian operator is obtained as part of the canonical quantization process, the time dependence of the state is described with the Schrödinger equation, just as with other quantum theories. Alternatively, the Heisenberg picture can be used where the time dependence is in the operators rather than in the states.
Probability amplitudes of observables in such systems are quite hard to evaluate, an enterprise which has absorbed considerable ingenuity in the last three quarters of a century. In practice, most often, expectation values of operators are computed systematically through covariant perturbation theory, formulated through Feynman diagrams, but path integral computer simulations have also produced important results. Contemporary particle physics relies on extraordinarily accurate predictions of such techniques.
Unification of fields and particlesEdit
The "second quantization" procedure outlined in the previous section takes a set of single-particle quantum states as a starting point. Sometimes, it is impossible to define such single-particle states, and one must proceed directly to quantum field theory. For example, a quantum theory of the electromagnetic field must be a quantum field theory, because it is impossible (for various reasons) to define a wavefunction for a single photon. In such situations, the quantum field theory can be constructed by examining the mechanical properties of the classical field and guessing the corresponding quantum theory. For free (non-interacting) quantum fields, the quantum field theories obtained in this way have the same properties as those obtained using second quantization, such as well-defined creation and annihilation operators obeying commutation or anticommutation relations.
Quantum field theory thus provides a unified framework for describing "field-like" objects (such as the electromagnetic field, whose excitations are photons) and "particle-like" objects (such as electrons, which are treated as excitations of an underlying electron field), so long as one can treat interactions as "perturbations" of free fields.
Physical meaning of particle indistinguishabilityEdit
The second quantization procedure relies crucially on the particles being identical. We would not have been able to construct a quantum field theory from a distinguishable many-particle system, because there would have been no way of separating and indexing the degrees of freedom.
Many physicists prefer to take the converse interpretation, which is that quantum field theory explains what identical particles are. In ordinary quantum mechanics, there is not much theoretical motivation for using symmetric (bosonic) or antisymmetric (fermionic) states, and the need for such states is simply regarded as an empirical fact. From the point of view of quantum field theory, particles are identical if and only if they are excitations of the same underlying quantum field. Thus, the question "why are all electrons identical?" arises from mistakenly regarding individual electrons as fundamental objects, when in fact it is only the electron field that is fundamental.
Particle conservation and non-conservationEdit
During second quantization, we started with a Hamiltonian and state space describing a fixed number of particles (N), and ended with a Hamiltonian and state space for an arbitrary number of particles. Of course, in many common situations N is an important and perfectly well-defined quantity, e.g. if we are describing a gas of atoms sealed in a box. From the point of view of quantum field theory, such situations are described by quantum states that are eigenstates of the number operator , which measures the total number of particles present. As with any quantum mechanical observable, is conserved if it commutes with the Hamiltonian. In that case, the quantum state is trapped in the N-particle subspace of the total Fock space, and the situation could equally well be described by ordinary N-particle quantum mechanics. (Strictly speaking, this is only true in the noninteracting case or in the low energy density limit of renormalized quantum field theories.)
For example, we can see that the free boson Hamiltonian described above conserves particle number. Whenever the Hamiltonian operates on a state, each particle destroyed by an annihilation operator is immediately put back by the creation operator .
On the other hand, it is possible, and indeed common, to encounter quantum states that are not eigenstates of , which do not have well-defined particle numbers. Such states are difficult or impossible to handle using ordinary quantum mechanics, but they can be easily described in quantum field theory as quantum superpositions of states having different values of N. For example, suppose we have a bosonic field whose particles can be created or destroyed by interactions with a fermionic field. The Hamiltonian of the combined system would be given by the Hamiltonians of the free boson and free fermion fields, plus a "potential energy" term such as
where and denotes the bosonic creation and annihilation operators, and denotes the fermionic creation and annihilation operators, and is a parameter that describes the strength of the interaction. This "interaction term" describes processes in which a fermion in state k either absorbs or emits a boson, thereby being kicked into a different eigenstate . (In fact, this type of Hamiltonian is used to describe the interaction between conduction electrons and phonons in metals. The interaction between electrons and photons is treated in a similar way, but is a little more complicated because the role of spin must be taken into account.) One thing to notice here is that even if we start out with a fixed number of bosons, we will typically end up with a superposition of states with different numbers of bosons at later times. The number of fermions, however, is conserved in this case.
In condensed matter physics, states with ill-defined particle numbers are particularly important for describing the various superfluids. Many of the defining characteristics of a superfluid arise from the notion that its quantum state is a superposition of states with different particle numbers. In addition, the concept of a coherent state (used to model the laser and the BCS ground state) refers to a state with an ill-defined particle number but a well-defined phase.
Beyond the most general features of quantum field theories, special aspects such as renormalizability, gauge symmetry, and supersymmetry are outlined below.
Early in the history of quantum field theory, as detailed above, it was found that many seemingly innocuous calculations, such as the perturbative shift in the energy of an electron due to the presence of the electromagnetic field, yield infinite results. The reason is that the perturbation theory for the shift in an energy involves a sum over all other energy levels, and there are infinitely many levels at short distances, so that each gives a finite contribution which results in a divergent series.
Many of these problems are related to failures in classical electrodynamics that were identified but unsolved in the 19th century, and they basically stem from the fact that many of the supposedly "intrinsic" properties of an electron are tied to the electromagnetic field that it carries around with it. The energy carried by a single electron—its self-energy—is not simply the bare value, but also includes the energy contained in its electromagnetic field, its attendant cloud of photons. The energy in a field of a spherical source diverges in both classical and quantum mechanics, but as discovered by Weisskopf with help from Furry, in quantum mechanics the divergence is much milder, going only as the logarithm of the radius of the sphere.
The solution to the problem, presciently suggested by Stueckelberg, independently by Bethe after the crucial experiment by Lamb and Retherford (the Lamb–Retherford experiment), implemented at one loop by Schwinger, and systematically extended to all loops by Feynman and Dyson, with converging work by Tomonaga in isolated postwar Japan, comes from recognizing that all the infinities in the interactions of photons and electrons can be isolated into redefining a finite number of quantities in the equations by replacing them with the observed values: specifically the electron's mass and charge: this is called renormalization. The technique of renormalization recognizes that the problem is tractable and essentially purely mathematical; and that, physically, extremely short distances are at fault.
In order to define a theory on a continuum, one may first place a cutoff on the fields, by postulating that quanta cannot have energies above some extremely high value. This has the effect of replacing continuous space by a structure where very short wavelengths do not exist, as on a lattice. Lattices break rotational symmetry, and one of the crucial contributions made by Feynman, Pauli and Villars, and modernized by 't Hooft and Veltman, is a symmetry-preserving cutoff for perturbation theory (this process is called regularization). There is no known symmetrical cutoff outside of perturbation theory, so for rigorous or numerical work people often use an actual lattice.
On a lattice, every quantity is finite but depends on the spacing. When taking the limit to zero spacing, one makes sure that the physically observable quantities like the observed electron mass stay fixed, which means that the constants in the Lagrangian defining the theory depend on the spacing. By allowing the constants to vary with the lattice spacing, all the results at long distances become insensitive to the lattice, defining a continuum limit.
The renormalization procedure only works for a certain limited class of quantum field theories, called renormalizable quantum field theories. A theory is perturbatively renormalizable when the constants in the Lagrangian only diverge at worst as logarithms of the lattice spacing for very short spacings. The continuum limit is then well defined in perturbation theory, and even if it is not fully well defined non-perturbatively, the problems only show up at distance scales that are exponentially small in the inverse coupling for weak couplings. The Standard Model of particle physics is perturbatively renormalizable, and so are its component theories (quantum electrodynamics/electroweak theory and quantum chromodynamics). Of the three components, quantum electrodynamics is believed to not have a continuum limit by itself, while the asymptotically free SU(2) and SU(3) weak and strong color interactions are nonperturbatively well defined.
The renormalization group as developed along Wilson's breakthrough insights relates effective field theories at a given scale to such at contiguous scales. It thus describes how renormalizable theories emerge as the long distance low-energy effective field theory for any given high-energy theory. As a consequence, renormalizable theories are insensitive to the precise nature of the underlying high-energy short-distance phenomena (the macroscopic physics is dominated by only a few "relevant" observables). This is a blessing in practical terms, because it allows physicists to formulate low energy theories without detailed knowledge of high-energy phenomena. It is also a curse, because once a renormalizable theory such as the standard model is found to work, it provides very few clues to higher-energy processes.
The only way high-energy processes can be seen in the standard model is when they allow otherwise forbidden events, or else if they reveal predicted compelling quantitative relations among the coupling constants of the theories or models.
On account of renormalization, the couplings of QFT vary with scale, thereby confining quarks into hadrons, allowing the study of weakly-coupled quarks inside hadrons, and enabling speculation on ultra-high energy behavior.
A gauge theory is a theory that admits a symmetry with a local parameter. For example, in every quantum theory, the global phase of the wave function is arbitrary and does not represent something physical. Consequently, the theory is invariant under a global change of phases (adding a constant to the phase of all wave functions, everywhere); this is a global symmetry. In quantum electrodynamics, the theory is also invariant under a local change of phase, that is – one may shift the phase of all wave functions so that the shift may be different at every point in space-time. This is a local symmetry. However, in order for a well-defined derivative operator to exist, one must introduce a new field, the gauge field, which also transforms in order for the local change of variables (the phase in our example) not to affect the derivative. In quantum electrodynamics, this gauge field is the electromagnetic field. The change of local gauge of variables is termed gauge transformation.
By Noether's theorem, for every such symmetry there exists an associated conserved current. The aforementioned symmetry of the wavefunction under global phase changes implies the conservation of electric charge. Since the excitations of fields represent particles, the particle associated with excitations of the gauge field is the gauge boson, e.g., the photon in the case of quantum electrodynamics.
The degrees of freedom in quantum field theory are local fluctuations of the fields. The existence of a gauge symmetry reduces the number of degrees of freedom, simply because some fluctuations of the fields can be transformed to zero by gauge transformations, so they are equivalent to having no fluctuations at all, and they, therefore, have no physical meaning. Such fluctuations are usually called "non-physical degrees of freedom" or gauge artifacts; usually, some of them have a negative norm, making them inadequate for a consistent theory. Therefore, if a classical field theory has a gauge symmetry, then its quantized version (the corresponding quantum field theory) will have this symmetry as well. In other words, a gauge symmetry cannot have a quantum anomaly.
In general, the gauge transformations of a theory consist of several different transformations, which may not be commutative. These transformations are combine into the framework of a gauge group; infinitesimal gauge transformations are the gauge group generators. Thus, the number of gauge bosons is the group dimension (i.e., the number of generators forming the basis of the corresponding Lie algebra).
All the known fundamental interactions in nature are described by gauge theories (possibly barring the Higgs multiplet couplings, if considered in isolation). These are:
- Quantum chromodynamics, whose gauge group is SU(3). The gauge bosons are eight gluons.
- The electroweak theory, whose gauge group is U(1) × SU(2), (a direct product of U(1) and SU(2)). The gauge bosons are the photon and the massive W± and Z⁰ bosons.
- Gravity, whose classical theory is general relativity, relies on the equivalence principle, which is essentially a form of gauge symmetry. Its action may also be written as a gauge theory of the Lorentz group on tangent space.
Supersymmetry assumes that every fundamental fermion has a superpartner that is a boson and vice versa. Its gauge theory, Supergravity, is an extension of general relativity. Supersymmetry is a key ingredient for the consistency of string theory.
It was utilized in order to solve the so-called Hierarchy Problem of the standard model, that is, to explain why particles not protected by any symmetry (like the Higgs boson) do not receive radiative corrections to their mass, driving it to the larger scales such as that of GUTs, or the Planck mass of gravity. The way supersymmetry protects scale hierarchies is the following: since for every particle there is a superpartner with the same mass but different statistics, any loop in a radiative correction is cancelled by the loop corresponding to its superpartner, rendering the theory more UV finite.
Since, however, no super partners have been observed, if supersymmetry existed it should be broken severely (through a so-called soft term, which breaks supersymmetry without ruining its helpful features). The simplest models of this breaking require that the energy of the superpartners not be too high; in these cases, supersymmetry could be observed by experiments at the Large Hadron Collider. However, to date, after the observation of the Higgs boson there, no such superparticles have been discovered.
The preceding description of quantum field theory follows the spirit in which most physicists approach the subject. However, it is not mathematically rigorous. Over the past several decades, there have been many attempts to put quantum field theory on a firm mathematical footing by formulating a set of axioms for it. Finding proper axioms for quantum field theory is still an open and difficult problem in mathematics. One of the Millennium Prize Problems—proving the existence of a mass gap in Yang–Mills theory—is linked to this issue. These attempts fall into two broad classes.
The first class of axioms, first proposed during the 1950s, include the Wightman, Osterwalder–Schrader, and Haag–Kastler systems. They attempted to formalize the physicists' notion of an "operator-valued field" within the context of functional analysis and enjoyed limited success. It was possible to prove that any quantum field theory satisfying these axioms satisfied certain general theorems, such as the spin-statistics theorem and the CPT theorem. Unfortunately, it proved extraordinarily difficult to show that any realistic field theory, including the Standard Model, satisfied these axioms. Most of the theories that could be treated with these analytic axioms were physically trivial, being restricted to low-dimensions and lacking interesting dynamics. The construction of theories satisfying one of these sets of axioms falls in the field of constructive quantum field theory. Important work was done in this area in the 1970s by Segal, Glimm, Jaffe and others.
Topological quantum field theoryEdit
During the 1980s, the second set of axioms based on topological ideas was proposed. Before 1980 all states of matter could be classified by geometry and the principle of broken symmetry. For example Einstein's theory of general relativity is based on the geometrical curvature of space and time, while crystals, magnets and superconductors can all be classified by the symmetries they break. In 1980 the quantum Hall effect provided the first example of a state of matter that has no spontaneous broken symmetry; its characterization is dependant on its topology and not on its geometry (See geometry v. topology). The quantum Hall effect can be described by extending quantum field theory into an effective topological quantum field theory based on the Chern–Simons theory. This line of investigation, which extends quantum field theories to topological quantum field theories, is associated most closely with Michael Atiyah and Graeme Segal, and was notably expanded upon by Edward Witten, Richard Borcherds, and Maxim Kontsevich. The main impact of topological quantum field theory has been in condensed matter physics where physicists have observed exotic quasiparticles such as magnetic monopoles and Majorana fermions. Topological field considerations could have radical applications in a new form of electronics called spintronics and topological quantum computers. The Standard Model allows for topological terms but is generally not formulated as a topological quantum field theory. Topological quantum field theory has also had broad impact in mathematics, with important applications in representation theory, algebraic topology, and differential geometry.
From a mathematically rigorous perspective, there exists no interaction picture in a Lorentz-covariant quantum field theory. This implies that the perturbative approach of Feynman diagrams in QFT is not strictly justified, despite producing vastly precise predictions validated by experiment. This is called Haag's theorem, but most particle physicists relying on QFT largely shrug it off, as it is not really limiting the power of the theory.
- Abraham–Lorentz force
- AdS/CFT correspondence
- Introduction to quantum mechanics
- Common integrals in quantum field theory
- Einstein–Maxwell–Dirac equations
- Form factor (quantum field theory)
- Green–Kubo relations
- Green's function (many-body theory)
- List of quantum field theories
- Quantization of a field
- Quantum electrodynamics
- Quantum field theory in curved spacetime
- Quantum flavordynamics
- Quantum hydrodynamics
- Quantum triviality
- Relation between Schrödinger's equation and the path integral formulation of quantum mechanics
- Relationship between string theory and quantum field theory
- Schwinger–Dyson equation
- Static forces and virtual-particle exchange
- Symmetry in quantum mechanics
- Theoretical and experimental justification for the Schrödinger equation
- Ward–Takahashi identity
- Wheeler–Feynman absorber theory
- Wigner's classification
- Wigner's theorem
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- It is related with, but not identical to the notion of causality. It says in effect, distant experiments yield uncorrelated results.
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- Special unitary groups in the Eightfold way completely determined the form of the theories, and current algebras implemented these symmetries in QFT without particular cognizance of dynamics, still producing a plethora of predictive correlations.
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bosons confirmed the theoretical prediction within one percent deviation.
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- Thorn et al. 2004
- Tong 2015, Chapter 1
- Brown, Lowell S. (1994). Quantum Field Theory. Cambridge University Press. ISBN 978-0-521-46946-3.
- Srednicki 2007, p. 19
- Srednicki 2007, pp. 25–26
- Zee 2010, p. 61
- Tong 2015, Introduction
- Zee 2010, p. 3
- Pais 1994. Pais recounts how his astonishment at the rapidity with which Feynman could calculate using his method. Feynman's method is now part of the standard methods for physicists.
- Newton & Wigner 1949, pp. 400–06
- If a gauge symmetry is anomalous (i.e. not kept in the quantum theory) then the theory is inconsistent: for example, in quantum electrodynamics, had there been a gauge anomaly, this would require the appearance of photons with longitudinal polarization and polarization in the time direction, the latter having a negative norm, rendering the theory inconsistent; another possibility would be for these photons to appear only in intermediate processes but not in the final products of any interaction, making the theory non-unitary and again inconsistent (see optical theorem).
- However, it is non-renormalizable. Veltman, M. J. G. (1976). "Methods in Field Theory, Proceedings of the Les Houches Summer School, Les Houches, France, 1975".
- Qi, Xiao-Liang; Zhang, Shou-Cheng (2010). "The quantum spin Hall effect and topological insulators" (PDF). Physics Today. 63 (1): 33–38. arXiv: . Bibcode:2010PhT....63a..33Q. doi:10.1063/1.3293411. ISSN 0031-9228.
- Ray, M. W.; Ruokokoski, E.; Tiurev, K.; Mottonen, M.; Hall, D. S. (2015). "Observation of isolated monopoles in a quantum field" (PDF). Science. 348 (6234): 544–47. Bibcode:2015Sci...348..544R. doi:10.1126/science.1258289. ISSN 0036-8075.
- Nadj-Perge, S.; Drozdov, I. K.; Li, J.; Chen, H.; Jeon, S.; Seo, J.; MacDonald, A. H.; Bernevig, B. A.; Yazdani, A. (2014). "Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor" (PDF). Science. 346 (6209): 602–07. arXiv: . Bibcode:2014Sci...346..602N. doi:10.1126/science.1259327. ISSN 0036-8075. PMID 25278507.
- Moskowitz, Clara (2 October 2014). "New Particle Is Both Matter and Antimatter". scientificamerican.com. Scientific American. Archived from the original on 2014-10-09.
- Historical references
- Born, M.; Jordan, P.; Heisenberg, W. (1926). "Zur quantenmechanic II" [On Quantum mechanics II]. Zeitschrift für Physik (in German). Springer Verlag. 35 (8). Bibcode:1926ZPhy...35..557B. doi:10.1007/BF01379806. ISSN 0044-3328. (Subscription required (. ))
- Dirac, P. A. M. (1927). "The quantum theory of the emission and absorption of radiation". Proc. R. Soc. Lond. A. Royal Society Publishing. 114 (767): 243–65. Bibcode:1927RSPSA.114..243D. doi:10.1098/rspa.1927.0039. (Subscription required (. ))
- General reader level
- Pais, A. (1994) . Inward Bound: Of Matter and Forces in the Physical World (reprint ed.). Oxford, New York, Toronto: Oxford University Press. ISBN 978-0198519973.
- Schweber, S. S. (1994). QED and the Men Who Made It: Dyson, Feynman, Schwinger, and Tomonaga. Princeton University Press. ISBN 9780691033273.
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- Thorn, J. J.; Neel, M. S.; Donato, W. V.; Bergreen, G. S.; Davies, R. E.; Beck, M.. (2004). "Observing the quantum behavior of light in an undergraduate laboratory" (PDF). Am. J. Phys. American Association of Physics Teachers. 72 (1210): 243–65. Bibcode:2004AmJPh..72.1210T. doi:10.1119/1.1737397.
- Introductory texts
- Peskin, M.; Schroeder, D. (1995). An Introduction to Quantum Field Theory. Westview Press. ISBN 0-201-50397-2.
- Scharf, Günter (2014) . Finite Quantum Electrodynamics: The Causal Approach (third ed.). Dover Publications. ISBN 978-0486492735.
- Zee, Anthony (2010). Quantum Field Theory in a Nutshell (2nd ed.). Princeton University Press. ISBN 978-0691140346.
- Advanced texts
- General readers
- Feynman, R.P. (2001) . The Character of Physical Law. MIT Press. ISBN 0-262-56003-8.
- Feynman, R.P. (2006) . QED: The Strange Theory of Light and Matter. Princeton University Press. ISBN 0-691-12575-9.
- Gribbin, J. (1998). Q is for Quantum: Particle Physics from A to Z. Weidenfeld & Nicolson. ISBN 0-297-81752-3.
- Schumm, Bruce A. (2004) Deep Down Things. Johns Hopkins Univ. Press. Chpt. 4.
- Introductory texts
- McMahon, D. (2008). Quantum Field Theory. McGraw-Hill. ISBN 978-0-07-154382-8.
- Bogolyubov, N.; Shirkov, D. (1982). Quantum Fields. Benjamin Cummings. ISBN 0-8053-0983-7.
- Frampton, P.H. (2000). Gauge Field Theories. Frontiers in Physics (2nd ed.). Wiley.
- Greiner, W; Müller, B. (2000). Gauge Theory of Weak Interactions. Springer. ISBN 3-540-67672-4.
- Itzykson, C.; Zuber, J.-B. (1980). Quantum Field Theory. McGraw-Hill. ISBN 0-07-032071-3.
- Kane, G.L. (1987). Modern Elementary Particle Physics. Perseus Group. ISBN 0-201-11749-5.
- Kleinert, H.; Schulte-Frohlinde, Verena (2001). Critical Properties of φ4-Theories. World Scientific. ISBN 981-02-4658-7.
- Kleinert, H. (2008). Multivalued Fields in Condensed Matter, Electrodynamics, and Gravitation (PDF). World Scientific. ISBN 978-981-279-170-2.
- Loudon, R (1983). The Quantum Theory of Light. Oxford University Press. ISBN 0-19-851155-8.
- Mandl, F.; Shaw, G. (1993). Quantum Field Theory. John Wiley & Sons. ISBN 978-0-471-94186-6.
- Ryder, L.H. (1985). Quantum Field Theory. Cambridge University Press. ISBN 0-521-33859-X.
- Schwartz, M.D. (2014). Quantum Field Theory and the Standard Model. Cambridge University Press. ISBN 978-1107034730.
- Ynduráin, F.J. (1996). Relativistic Quantum Mechanics and Introduction to Field Theory (1st ed.). Springer. ISBN 978-3-540-60453-2.
- Advanced texts
- Brown, Lowell S. (1994). Quantum Field Theory. Cambridge University Press. ISBN 978-0-521-46946-3.
- Bogoliubov, N.; Logunov, A.A.; Oksak, A.I.; Todorov, I.T. (1990). General Principles of Quantum Field Theory. Kluwer Academic Publishers. ISBN 978-0-7923-0540-8.
- 't Hooft, Gerard (2007). Butterfield, J.; Earman, John, eds. Philosophy of Physics. Part A. The Conceptual Basis of Quantum Field Theory: Elsevier. pp. 661–730 – via ScienceDirect. (Subscription required (. )) On web at 't Hooft's university website
|One-dimensional quantum field theory on Wikiversity|
- Hazewinkel, Michiel, ed. (2001) , "Quantum field theory", Encyclopedia of Mathematics, Springer Science+Business Media B.V. / Kluwer Academic Publishers, ISBN 978-1-55608-010-4
- Stanford Encyclopedia of Philosophy: "Quantum Field Theory", by Meinard Kuhlmann.
- Siegel, Warren, 2005. Fields. A free text, also available from arXiv:hep-th/9912205.
- Quantum Field Theory by P. J. Mulders | <urn:uuid:551af1c5-8b8a-4cd6-bd2f-ed5482f8f5d3> | 3.171875 | 14,833 | Knowledge Article | Science & Tech. | 41.015346 | 95,579,373 |
April 24 (UPI) — The end of the last ice age was precipitated by a shift in the circulation of the North Pacific Ocean some 15,000 years ago.
According to new research by scientists at the University of St. Andrews, the altered circulation released large amounts of CO2 into the atmosphere, warming Earth’s climate.
Scientists modeled the ancient shifts in circulation and ocean-atmosphere gas exchange by measuring the chemical composition of foraminifera, the tiny fossil shells left behind by plankton. Their analysis — published this week in the journal Nature Geoscience — revealed an uptick in the amount of CO2 released by the North Pacific beginning 15,000 years ago. Previous studies have found evidence of shifting circulation patterns in the Atlantic at roughly the same time.
Earlier this month, another group of researchers published a study showing the Atlantic’s circulation is slowing down. Scientists suggest a slowdown could significantly alter climate patterns across the globe.
“In our study we see very rapid changes in the climate of the North Pacific that we think are linked to past changes in ocean currents in the Atlantic,” lead researcher Will Gray, an environmental scientist at St. Andrews, said in a news release. “This gives us an example of the way that different parts of the climate system are connected, so that changes in circulation in one region can drive changes in CO2 and oxygen all the way over on the other side of the planet.”
Gray and his colleagues also found shifting North Pacific circulation patterns have led to a reduction in the amount of oxygen in the deep ocean. Previous studies have shown regions of low-oxygen and no-oxgyen in Earth’s oceans are growing in size and number.
For climate scientists, understanding the exchange of CO2 between Earth’s oceans and atmosphere is essential to accurately modeling climate change.
“The North Pacific Ocean is very big and just below the surface the waters are brimming with CO2; because of this, we really need to understand how this region can change in the future, and looking into the past is a good way to do that,” Gray said.
While natural shifts in ocean circulation and ocean-atmosphere gas exchange fueled relatively dramatic climate change at the end of the last ice age, scientists say those changes happened much slower than man-made climate change.
“Humans have driven CO2 rise in the atmosphere as large as the CO2 rise that helped end the last Ice Age, but the man-made CO2 rise has happened 100 times faster,” said St. Andrews researcher James Rae. “This will have a huge effect on the climate system, and one that we are only just beginning to see.” | <urn:uuid:717a2ef9-c3d0-4fa3-8497-277df2a8d5a9> | 3.84375 | 564 | News Article | Science & Tech. | 39.394204 | 95,579,377 |
Since 2015, Google has been working on “Project Sunroof,” a program that’s geared to tell consumers if switching to solar panels on their roof is the right call. While powering your house via the sun is a greener and likely cheaper alternative in the long run, it wouldn’t do much good if there wasn’t adequate sunlight reaching the area. Google, in partnership with a few German companies, has been able to expand the product into the German market.
Earlier this week, Germany’s residents have been able to use Project Sunroof to see if their house makes sense to switch to solar energy. This was made possible through a collaboration with E.ON, an energy company, and Tetraeder, a software maker. Initially, 40 percent of the country will be able to see extensive data, which is roughly seven million people and it will be mostly in densely-populated areas. Google announced that this was the first time this technology has been available outside of the United States.
The process of finding out information on a specific house is very easy. For those that live in Germany, they simply log on to and put in their address. , explains how the process works. A couple of the company’s products, including Google Earth and Google Maps, uses information from their satellites to figure out how much of the sun is usable as solar energy. It will then analyze this data based on roof layout, typical weather in the area, and if there are any obstructions in the way. Finally, it'll figure out approximately how much money can be saved based on all this information it was able to retrieve.
Much of the US already has the ability to see how much they could save with the switch to solar energy. In similar form, it’s as simple as and typing their home address in. Again, it will analyze the house, whether or not the rooftop is adequate enough to gather energy from the sun, and it will estimate savings based on the amount being paid for electricity. The areas highlighted in orange are places around the country that can get information.
Similar to Germany, most of the densely-populated areas are able to find out if the alternative energy is right for them. Project Sunroof has hit all 50 states, but most of those people living in rural areas and smaller towns won’t have much luck. The West Coast has more coverage with much of California, Arizona, Utah, and western parts of Oregon and Washington all available.
Making the switch to solar panels is still very expensive. The average amount to install them is roughly $17,000. Homeowners can expect to get that money back in the long term, however, as some can save up to $1,000 or more per year on their electricity. This technology will only get cheaper as researchers also find alternative ways to obtain solar energy. For example, the could significantly cut down on manufacturing costs.
Researchers from marine life advocates Oceana have discovered a surprising new world under the sea near Sicily.
Sweden's aggressive target of generating over 40 terawatt-hours of renewable energy by 2030 could be reached nearly a decade early. A massive amount of wind power projects could hit a snag in market value with subsidies, but SWEA could push to close those up by the end of the year.
Starbucks is ramping up its sustainability efforts with a plan to eradicate the use of plastic straws in its assembly line. | <urn:uuid:ee30157a-020d-4f81-84be-6eb82248baa0> | 2.921875 | 711 | News Article | Science & Tech. | 47.589515 | 95,579,378 |
Origins of Sedimentary Rock MCQs Quiz Worksheet PDF Download
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MCQ. As layers keep on deposited over older layers, older layers turn/become | <urn:uuid:aa56033f-74a9-41d4-84eb-70aae9018424> | 3.90625 | 270 | Product Page | Science & Tech. | 48.441976 | 95,579,389 |
Myanmar, Liberia, and the United States of America. Those are the only three countries left in the world that don’t use the metric system. Ted-Ed traces the history of the metric system (thank you French Revolution) to show how important it is to have one universal measurement system for the world, what can happen when conversions go wrong (NASA crashing an orbiter into Mars), and what the future of the metric system will be (basing it off universal constants like the speed of light).
For the majority of recorded human history, units like the weight of a grain or the length of a hand weren’t exact and varied from place to place. Now, consistent measurements are such an integral part of our daily lives that it’s hard to appreciate what a major accomplishment for humanity they’ve been. | <urn:uuid:247343e2-1121-4f4f-9c97-4936e3541b42> | 2.9375 | 170 | Truncated | Science & Tech. | 42.768155 | 95,579,391 |
Flowering plants naturally know when they need to spare or perish their cells. In a new study reported in Cell, scientists at WPI-ITbM, Nagoya University have examined the ovules of plant cells to reveal a novel cell-elimination system based on an unusual cell fusion.
Uncovering the mystery on the evolution of fertilization in Arabidopsis by live cell imaging
Flowering plants naturally know when they need to spare or perish their cells. In a new study reported in Cell, an international group of plant biologists at ITbM, Nagoya University and other research institutes, have examined the ovules of plant cells by live-imaging to reveal a novel cell-elimination system based on an unusual cell fusion. This uncovers the mechanism on how flowering plants prevent further attraction of multiple pollen tubes after successful fertilization.
Nagoya, Japan – Dr. Daisuke Maruyama and Professor Tetsuya Higashiyama at the Institute of Transformative Bio-Molecules (WPI-ITbM) of Nagoya University and the JST-ERATO Higashiyama Live-Holonics Project along with their international team have shown by live-cell imaging techniques that flowering plants, such as Arabidopsis thaliana undergo a cell to cell fusion to prevent the attraction of the second pollen tube after fertilization has occurred.
Cell to cell fusion is known to be extremely rare in plant cells due to the presence of the relatively tough cell wall. Only two other examples of plant cell fusion have been observed so far, and over 110 years have passed since the identification of the two cell fusions, which occurred between two sets of gametes during fertilization. Consequently, this research reports the third plant cell fusion event that was identified during normal developmental processes of flowering plants.
The study, published online on April 23, 2015 in the journal Cell, outlines the complicated mechanism of communication between plant cells, where an unusual cell fusion induces selective elimination of the cell responsible for pollen tube attraction after successful fertilization. This research reveals a new type of cell fusion that is initiated to destroy a particular cell, and enlightens the evolution of sexual reproduction in flowering plants.
Sexual reproduction in flowering plants occurs by fertilization of the female gamete (a reproductive cell) by a male gamete. Upon successful pollination on the stigma, the pollen tube grows down through the pistil towards the ovary. The mature ovule in most flowering plants, including Arabidopsis thaliana, contains a seven-celled embryo sac consisting of two synergid cells, one egg cell, one central cell and three antipodal cells.
The pair of synergid cells are located adjacent to the egg cell and Higashiyama’s group have reported in 2001 that the synergid cells are necessary for attracting the pollen tube towards the ovule. The pollen tube enters the ovule through an opening called the micropyle. Flowering plants undergo double fertilization by penetration of the pollen tube through one of the synergid cells (degenerated synergid cell), followed by rupture of the pollen tube to discharge the two sperm cells into the embryo sac.
The two sperm cells independently fertilize the egg cell and the central cell to produce the embryo and the endosperm (a tissue that surrounds and nourishes the embryo), respectively, which eventually develops into a seed. Once fertilization has occurred, the second synergid cell (persistent synergid cell) degenerated within a few hours of successful fertilization.
As a result, additional pollen tubes no longer approach the fertilized ovary, a mechanism termed as ‘polytubey block’ (polytubey = a condition where an ovule receives multiple pollen tubes). On the other hand, in the event of unsuccessful fertilization, the second synergid cell persists and attracts a second pollen tube to recover the failure of earlier fertilization.
“Although the role of synergid cells has been identified, we did not exactly know how the persistent synergid cell is degenerated and induces the polytubey block mechanism upon successful fertilization,” says Daisuke Maruyama, an Assistant Professor at Nagoya University who is the first author and leader of this research. “Through examination of Arabidopsis ovules by highly sensitive live-imaging, we were able to see that successful fertilization of the two female gametes triggers an unprecedented cell fusion between the persistent synergid cell and the endosperm (SE fusion), which eventually leads to inactivation of the persistent synergid cell.”
SE fusion, which is induced by fertilization of the central cell, causes rapid dilution of the pre-secreted pollen tube attractant in the persistent synergid cell. Transmission electron microscopy of the unfertilized ovule revealed a very thin cell wall between the synergid cell and central cell wall, which was assumed to be necessary for rapid disintegration of the cell walls. The SE fusion appeared to control the elimination of the persistent synergid nucleus, as disorganization of the nucleus synchronized with proliferation of the endosperm after SE fusion. A continuous cytoplasm between the persistent synergid cell and the endosperm was also observed, providing evidence for fusion of the two cells. On the other hand, fertilization of the egg cell strongly activates ethylene signaling, which also induces selective disorganization of the nucleus in the persistent synergid cell. Thus, the persistent synergid cell completely loses its pollen tube attracting function by synergetic SE fusion and ethylene signaling.
“We were extremely excited when we saw that cell fusion occurs between the persistent synergid cell and the endosperm, as the idea of cell fusion is not very common in plant cells,” says Maruyama, who made this discovery in 2012. “We continued to look into this phenomena to gain mechanistic insight and found evidence of a unique three-step mechanism for polytubey block, where the egg cell and the central cell coordinately play key roles in eliminating the persistent synergid cell by cell fusion and subsequent nuclear disorganization.”
Maruyama and Higashiyama’s investigation solves the mystery of the sophisticated switch-off mechanism for further fertilization (attraction of multiple pollen tubes) upon successful fertilization in flowering plants. Double fertilization of the female gametes triggers an unusual cell fusion, followed by specific cell disorganization that inactivates the cell responsible for attracting pollen tubes. Interestingly, flowering plants are also able to cancel this polytubey block mechanism when fertilization from the first pollen tube is fruitless. As a result, this enables attraction of the second pollen tube and restores the chance of fertilization. “We have succeeded in perceiving a unique cell fusion mechanism that arises from initial fertilization in flowering plant cells,” says Maruyama. “We believe that the discovery of this work sheds light on elucidating cell fusion events and further understanding of the fertilization mechanism in plants. This may lead to the development of new ways to improve the success rate of fertilization in plants, which may have useful applications in agricultural production.”
This article “Rapid elimination of the persistent synergid through a cell fusion mechanism” by Daisuke Maruyama*, Ronny Völz, Hidenori Takeuchi, Toshiyuki Mori, Tomoko Igawa, Daisuke Kurihara, Tomokazu Kawashima, Minako Ueda, Masaki Itoh, Masaaki Umeda, Shuh-ichi Nishikawa, Rita Groß-Hardt and Tetsuya Higashiyama, is published online on April 23, 2015 in Cell.
DOI: 10.1016/j.cell.2015.03.018 (http://dx.doi.org/10.1016/j.cell.2015.03.018)
About WPI-ITbM (http://www.itbm.nagoya-u.ac.jp/)
The Institute of Transformative Bio-Molecules (ITbM) at Nagoya University in Japan is committed to advance the integration of synthetic chemistry, plant/animal biology and theoretical science, all of which are traditionally strong fields in the university. ITbM is one of the research centers of the Japanese MEXT (Ministry of Education, Culture, Sports, Science and Technology) program, the World Premier International Research Center Initiative (WPI). The aim of ITbM is to develop transformative bio-molecules, innovative functional molecules capable of bringing about fundamental change to biological science and technology. Research at ITbM is carried out in a "Mix-Lab" style, where international young researchers from various fields work together side-by-side in the same lab, enabling interdisciplinary interaction. Through these endeavors, ITbM will create "transformative bio-molecules" that will dramatically change the way of research in chemistry, biology and other related fields to solve urgent problems, such as environmental issues, food production and medical technology that have a significant impact on the society.
JST-ERATO Higashiyama Live-Holonics Project (http://www.liveholonics.com/top.html)
Individual cells of multicellular organisms communicate with neighboring cells to maintain the organism. Each cell in a multicellular organism learns its role in the cell population through dynamic and intricate communication with surrounding and distant cells. We call this cell-to-cell communication as “holonic communication”. However, it is still unclear how cells actually communicate with each other in a living organism. The goal of this project is to understand holonic communication in a living, multicellular organism. For this purpose, our project sets up three research groups for optical technology, nano-engineering, and single-cell omics to make a new frontier in ‘live cell biology’ - the real-time analysis of intercellular signaling in multicellular organisms. For live-cell analyses with complete control under the microscope, various new technologies are expected to be developed such as live-cell and single-molecule imaging, manipulation techniques for cell and molecules, interdisciplinary studies of plant biology and engineering technologies, and nano- and micro-device engineering. These technologies will be applicable to other fields, not only scientific instruments but also diagnosis methods for medical care, reproductive medicine, and breeding techniques for agriculture.
Dr. Daisuke Maruyama
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University
Furo-Cho, Chikusa-ku, Nagoya 464-8602, Japan
TEL: +81-52-747-6404 FAX: +81-52-747-6405
Dr. Ayako Miyazaki
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University
Furo-Cho, Chikusa-ku, Nagoya 464-8601, Japan
TEL: +81-52-789-4999 FAX: +81-52-789-3240
Nagoya University Public Relations Office
TEL: +81-52-789-2016 FAX: +81-52-788-6272
Ayako Miyazaki | ResearchSEA
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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While it is well-known that roads can spread invasive weeds, new research shows that some roads are worse than others. In Utah, areas along paved roads were far more likely to be invaded than those along 4-wheel-drive tracks. This suggests that limiting road improvements would help keep out invasive weeds.
"Each step of road improvement would appear to convert an increasing area of natural habitat to roadside habitat," say Jonathan Gelbard, who did this work while at Duke University in Durham, North Carolina, and is now at the University of California at Davis, and Jayne Belnap of the U.S. Geological Survey in Moab, Utah, in the April issue of Conservation Biology.
Cheatgrass, knapweeds and other non-native plants have invaded nearly 125 million acres of the American West. Roads are a big part of the problem: for instance, vehicles can transport non-native seeds into uninfested areas, and clearing land during road construction gives weed seeds a place to become established. Intuitively, it makes sense that improved roads would spread weeds more than primitive roads because the former have more traffic, more exposed soil and more maintenance such as mowing and herbicide treatments, all of which can favor invasive species.
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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In the case of ODBC, the drivers encapsulate many functions that can be broken down into several broad categories. Some of these were mainframe related, designed to allow programs running on those machines to translate between the variety of SQL’s and provide a single common interface which could then be called by other mainframe or microcomputer programs. However, by then Microsoft had changed focus to their OLE DB concept recently reinstated , which provided direct access to a wider variety of data sources from address books to text files. The introduction of SQL aimed to solve the problem of language standardization, although substantial differences in implementation remained. In effect, all such systems were static, which presented considerable problems.
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ODBC is based on the device driver model, where the driver encapsulates the logic needed to types of odbc a standard set of commands and functions into the specific calls ofbc by the underlying system. These included features like scrollable cursorsand types of odbc information queries.
What was missing was the SQL parser that could convert those calls from their text form into the C-interface used in Jet.
Open Database Connectivity
Microsoft included drivers for Excel to turn its spreadsheet documents into SQL-accessible database tables. This meant that types of odbc single library could be used with potentially any programming language on a given platform. It is not uncommon to find ODBC drivers for database engines that are meant to be embedded, like SQLiteas a way to allow existing tools to act as front-ends to these engines for testing and debugging. Archived October 5,at the Wayback Machine.
Retrieved 13 December A proposed standard was released in Decemberand industry input was gathered and worked into the system throughresulting types of odbc yet another name change to ODBC. During this time, Microsoft was in the midst of developing their Jet database system.
MySQL :: MySQL Connector/ODBC Developer Guide :: Connector/ODBC Data Types
Also, since the SQL language had only rudimentary programming features, users often wanted to use SQL within a program written in another language, say Fortran or C. The introduction of the types of odbc -based relational database during the s led to a proliferation of data access methods. All of this is included in the driver and the DSNs. Jet combined three primary subsystems; an ISAM -based database engine also named Jetconfusinglya C-based interface allowing applications to access that types of odbc, and a selection of driver dynamic-link libraries DLL that allowed the same C interface to redirect input and output to other ISAM-based databases, like Paradox and xBase.
Over time, database vendors took over the driver interfaces and provided direct links to their products. These systems may or may types of odbc allow other applications to access the data directly, and those that did use a wide variety of methodologies.
From Wikipedia, the free encyclopedia. Much of the system was based on Sybase’s DB-Library system, with the Sybase-specific sections removed and several additions to support other platforms.
Rypes drivers are normally enumerated, set up and managed by a separate Manager layer, which may provide additional functionality. Some drivers offer extra functionality not defined by the standard. The DM also includes the ability to save partially complete DSN’s, types of odbc code and logic typez ask the types of odbc for any missing information at runtime.
This frees the application developer from having to create this sort of code, as well types of odbc having to know which questions to ask.
This provider translates ADO. Third parties have also developed such.
Types of odbc were several types of odbc with the Embedded SQL approach. For instance, a DSN can be created without a required password. At the first meeting there was considerable debate over whether or not the effort should work solely on the SQL types of odbc itself, or attempt a wider standardization which included a dynamic SQL language-embedding system as well, what they called a Call Level Interface CLI.
Jet allowed using one set gypes calls to access common microcomputer databases in a fashion similar to Blueprint, by then renamed DataLens. Digital Equipment and Oracle both contracted Simba Technologies to develop drivers for their databases as well. Programmers usually use such a bridge when a given database lacks an ADO.
This would not only make Windows a premier typew for CLI development, but also allow users to use SQL to access both Jet and other databases as well. New perspectives on information systems development: For instance, the same MySQL driver can be used to types of odbc to any MySQL server, but the connection types of odbc to connect to a local private server is different from the information needed to connect to an internet-hosted public server. | <urn:uuid:75abb669-0a1f-411f-809b-3fd159e56935> | 3.359375 | 1,064 | Knowledge Article | Software Dev. | 32.548278 | 95,579,434 |
Automated Solid-Phase Extraction of Oraganochlorine Pesticides from Drinking Water
Poster Jul 30, 2014
Frans Schoustsen and Pranathi R Perati
Organochlorine pesticides (OCP) are a class of chemicals that were used to control insect pests since the 1940s. The use of OCPs was banned in the later part of last century due to their longevity, a trait that made them effective for long term pest control, but also increased concerns of potential health outcomes such as cancer in humans and ecosystem disruption.
Pesticides are regulated in the U.S. by the Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Some states also regulate pesticides under FIFRA, in a more restrictive manner than the EPA. The Stockholm Convention on Persistent Organic Pollutants, a UN treaty, has established global bans on several organochlorine pesticides including DDT, hexachlorobenzene, pentachlorobenzene, chlordane, dieldrin, endrin, heptachlor, mirex, toxaphene, hexachlorocyclohexane (alpha-HCH, beta-HCH, and gamma-HCH (lindane)), and chlordecone.
OCPs can be highly toxic, are hydrophobic, lipophilic, and extremely stable. Once in the air, water, and soil, they are subject to global deposition processes and bioaccumulation in the food chain. Diet is the main source of human exposure, primarily through food consumption where OCPs have bioaccumulated.
In this study twenty chlorinated pesticides were extracted from drinking water using a Thermo Scientific™ Dionex™ AutoTrace™ 280 Solid-Phase Extraction instrument and the Thermo Scientific™ Dionex™ SolEx™ C 18 cartridges. The recoveries were compared to the traditional liquid-liquid extraction method (LLE). Analysis for both sample preparation methods was performed by gas chromatography with Electron Capture Detection (GC-ECD)
Profiling Personal Air Pollutant Exposures Using a Wearable Non-Selective Passive WristbandPoster
Characterizing cumulative exposure to air pollutant mixtures is a critical step in understanding disease development. The Fresh Air wristband was tested as a personal exposure assessment tool with promising results.READ MORE
Sport Doping Screening in Biological Matrices by Multi-Dimensional LC-QToFPoster
This work evaluated the performance of 2D LC variant using a QToF setup instead of a triple quadrupole mass spectrometer for the analysis of drug of abuse in urine targeting low and sub ppb level.READ MORE
Analysis of Doping and Forensic Drugs in Urine Using High-Resolution GC/Q-TOFPoster
In this study, we are examining the potential for high resolution accurate mass 7250 GC/Q-TOF equipped with low energy EI source, for both quantitative and screening aspects of doping control and forensic drugs applications.READ MORE
15th International Conference and Exhibition on Metabolomics & Systems
Apr 29 - Apr 30, 2019 | <urn:uuid:ef4b2924-84d6-4a6a-8d93-57f398abe9df> | 2.8125 | 659 | Content Listing | Science & Tech. | 10.262953 | 95,579,460 |
How many digits of pi have been discovered?
1.2411 trillion digits (1,241,100,000,000) digits of pi have been dicovered.
9 people found this useful
i hate this website i just wanted ot know how many digits pi was and then somehow i got here! like i know that is why i was asking you you stupid program!!! you can't even tel…l me how many numbers pi has been figured to! some website to get answers!
as of October 17, 2011, the record for pi is over 10 trillion digits (10,000,000,000,000)
The last digits of pi are unknown. The number is not a rational number and will continue on out to infinity. There was a satire written as a news story that appeared, but it w…as not true.
Isaac Newton got up to 16 digits of pi when using his method or he calculated 3.1415926535897932
Me, 73. 3.14159265358979323846264338327950288419716939937510582097494459230 7816406. A lot, huh?
the current record for decimal places that pi has been calculated to is 1,241,100,000,000 THIS IS MORE THAN A TRILLION * * * * * As of 17 October 2011, the answer is 10 …trillion.
Apparently more than five trillion digits.
The "Pi Computer Project" or PCP finished some time in November 2010, it calculated about 5 trillion digits! * * * * * But the number crunching goes on! As of 17 October… 2011, the answer is 10 trillion.
Answer: No. Pi is irrational; we could never find the last digit,because the digits go on forever. Also, being irrational means thatthe digits don't repeat periodically.
A Japanese psychiatrist memorized 83,431 digits of pi. This man is Akira Haraguchi.
the record is set at 2.7 trillion decimal places * * * * * As of 17 October 2011, the answer is 10 trillion.
So far it's been calculated to well over a trillion decimal places ! The final answer will never be known - since the value of Pi is a never-ending number that (up to now) d…oesn't exhibit any repetitive sequence of digits. Theoretically, someone could calculate the number for the rest of their lives and never reach a final solution !
It's been proven that pi is an irrational number. In other words, it can't be written with a finite number of digits, and there is no 'last digit'.
As of 17 October 2011, the answer is 10 trillion. See link.
As of 17 October 2011, the answer is 10 trillion = 10 13 . While there are repeats of short patterns from time to time, the decimal representation does not - and cannot - se…ttle into a repeating pattern. | <urn:uuid:97a3325b-f381-4777-8ea8-0c8fbf50ecb4> | 2.578125 | 611 | Q&A Forum | Science & Tech. | 76.399284 | 95,579,465 |
Determine the slope of the line perpendicular to the line p: y = -x +4.
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A team of scientists found that a strengthened change in ocean temperatures from west to east (or gradient) in the tropical Pacific during the preceding winter is the main driver of more frequent heat waves in Texas.
Check out research and program highlights, as well as MAPP Task Force updates.
NOAA’s Modeling, Analysis, Predictions and Projections program (MAPP) and NIDIS have just launched an interactive presentation that analyzes and explains the historic drought that impacted California from 2011 to 2017. This presentation, called a “Story Map” takes users through a visual history of the drought, using images and graphs to provide an interactive and engaging experience.
Participants from NOAA and its 12 testbeds, including NOAA MAPP Program-funded investigators leading projects under the Climate Test Bed, and other academic and private sector partners met for the 9th annual workshop to enhance communication and exchange lessons-learned and best practices across the current NOAA and related test beds/proving grounds.
To bring attention to the important challenge of providing detailed predictions of the atmosphere, ocean, and land, and scope and evaluate future directions, NOAA and the Department of Energy co-hosted a workshop on the Initialization of High-Resolution Earth System Models bringing together experts from the climate modeling community.
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Carbon dating is no sign up dating sight
The approach was a sensation when it was introduced.
The chemist who developed carbon dating, Willard Libby, won the Nobel Prize for his work.
We will deal with carbon dating first and then with the other dating methods.
Today, carbon dating is used so widely as to be taken for granted.Familiar to us as the black substance in charred wood, as diamonds, and the graphite in “lead” pencils, carbon comes in several forms, or isotopes.One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or C ratio gets smaller.The other two isotopes in comparison are more common than carbon-14 in the atmosphere but increase with the burning of fossil fuels making them less reliable for study (2); carbon-14 also increases, but its relative rarity means its increase is negligible. After this point, other Absolute Dating methods may be used.
Today, the radiocarbon-14 dating method is used extensively in environmental sciences and in human sciences such as archaeology and anthropology.The Mayan calendar used 3114 BC as their reference. | <urn:uuid:f0d04fdb-13a0-4c3b-8cfe-dde8dce22bd2> | 3.578125 | 238 | Knowledge Article | Science & Tech. | 46.453 | 95,579,487 |
30 Jun , 2018 by Matt Williams
Using data from ground-based observatories and the Hubble space telescope, an international team of scientists found evidence that ‘Oumuamua is an interstellar comet after all.
23 May , 2018 by Matt Williams
A new study by a pair of astronomers has indicated that near Jupiter, there is an interstellar asteroid that has been there since the early days of the Solar System.
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Asteroids, Astronomy, Comets
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Biologists have discovered a new super-family of developmental proteins that are critical for cell growth and differentiation and whose further study is expected to benefit research on cancer and the nerve-cell repair.
The protein super-family, which existed before the emergence of animals about 850 million years ago, is of major importance for understanding how life evolved in primordial times. The discovery will be described in the 14 February 2007 issue of the journal PLoS ONE.
"This super-family is highly divergent, even in animals with an ancient lineage such as the sea anemone. This super-family also evolves rapidly, so its proteins may provide a model system for investigating how rapidly mutating genes contribute to, and are likely necessary for, the diversity and adaptability of animal life," explains Penn State Assistant Professor Randen Patterson, the senior author of the study. The new protein superfamily is named "DANGER," an acronym for "Differentiation and Neuronal Growth Evolve Rapidly."
The discovery was led by Patterson and Damian van Rossum, a postdoctoral scholar at Penn State in University Park, Pennsylvania, and collaborators at Johns Hopkins University in Baltimore, Maryland. "Most DANGER proteins have not been researched, but from what little we do know these proteins, they are critical for cell growth and differentiation," van Rossum says.
Because so many genomes for diverse organisms have been sequenced and annotated, the discovery of a new and deeply rooted protein family is quite rare. The relationship of the six family members comprising the DANGER super-family escaped detection due to the high rates of mutations between family members, although a few family members had been detected previously and had been shown to control the differentiation of cells into organs in worms, fish, and mice. Deletion of these their DANGER genes led to gross structural changes and prenatal death.
These findings also have clinical relevance, according to the researchers. "Many DANGER proteins are surrounded by transposable elements, which are pieces of DNA around genes that help the genes migrate back and forth throughout the genome," Patterson says. Because of this feature, DANGER genes can move throughout the genome, which could have positive or negative health consequences. "One member of the gene family resides in the genome at an area responsible for a human disease, the Smith-Magenis syndrome, which results in severe physical and mental retardation," Patterson explains. "DANGER genes also contain transposable elements that may participate in the genetic disturbances associated with chronic myeleoid leukemia."
One member of the super-family has been identified as playing a role in the development of the nervous system. "In cell culture and spinal cord neurons, the protein coded for by this gene stimulates lengthening and branching of neurons," Patterson says. Because many other DANGER proteins also are expressed in neurons, discovering their functions may be a key to deciphering the complexity of neuronal growth and development.
In addition to Patterson and van Rossum, investigators in this study include N. Nikolaidis and D. Chalkia at Penn State and D. N. Watkins, R. K. Barrow, and S. H. Snyder at Johns Hopkins. The research was supported by grants from the National Institutes of Health and the Searle Foundation.
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:dc519a9a-7030-4921-af2e-067a9a53d496> | 3.453125 | 1,297 | Content Listing | Science & Tech. | 35.119719 | 95,579,511 |
Crystal Geometry. I
Crystallography grew up as a branch of mineralogy, and involved mainly the recognition, description, and classification of naturally occurring crystal species. X-ray crystallography is a relatively new discipline, dating from the discovery in 1912 of the diffraction of x-rays by crystals. That year marked the beginning of the experimental determination of crystal structures. Figure 1.1 illustrates the structure of sodium chloride, which was among the first crystals to be studied by x-ray techniques.
KeywordsPoint Group Stereographic Projection Parametral Plane Miller Index Symmetry Operation
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General and Historical Study of Crystallography
Crystal Morphology and Stereographic Projection
- Phillips, F.C., An Introduction to Crystallography, London, Longmans (1971).Google Scholar
Crystal Symmetry and Point Groups
- Hahn, T. (Editor), International Tables for Crystallography, Vol. A, Dordrecht, D. Reidel (1983).Google Scholar
- Henry, N. F. M., and Lonsdale, K. (Editors), International Tables for X-ray Crystallography, Vol. I, Birmingham, Kynoch Press (1965).Google Scholar
- Ladd, M. F. C., Symmetry in Molecules and Crystals, Chichester, Ellis Horwood (1989).Google Scholar | <urn:uuid:f71b957b-2bd4-4412-a34e-526224fc598d> | 3.3125 | 297 | Truncated | Science & Tech. | 39.530156 | 95,579,527 |
I am very new to python, but I hear that it can be used to handle web forms. Does anybody know of where I can find a good tutorial on how to create something that will handle form input? Thanks in advance.
and the script that it passes info to in the cgi-bin
import cgitb; cgitb.enable()
# get the info from the html form
form = cgi.FieldStorage()
#set up the html stuff
reshtml = """Content-Type: text/html\n
User = form['UserName'].value
Pass = form['PassWord'].value
if User == 'john' and Pass == 'jacob':
print 'mr. Jingleheimerschmidt !</big></big><br>'
print 'Sorry, incorrect user name or password'
if you are using Linux, remember to make the login.py
chmod a+x /whatever/the/path/is/to/your/cgi-bin/login.py
let me know how it works.
also. if it does not work, lemme know some other stuff
what web server you are using.....
etc... what ever you think may help diagnose.
I tried running what you sent me and it didn't seem to work. When I tell python to print something (such as all the html code along with the form data) where is it printing it to? I'm also very new to networking and things like that. Would I have to upload my python code and html file to my web site for it to run properly, or will it run right just straight off of my computer?(I have Windows XP with python installed). When I upload it to my web site, I believe it is an apache server. Thanks for your help in advance.
Also, the web site says that it supports scripting languages such as perl, php, etc.. but it does not exactly say that it supports python. Does it need to say that? The web site was purchased from Lonex <www.lonex.com>
first off, many web hosts support scripting languages, but as they include php, perl, etc.. many do not support python.
the good news is...
you can host the site yourself.
apache is available for windows and they have great documentation and support.
heck, i will even host your site (i am hosting four sites now) if you are not going to get more than a thousand hits/day.
what i am saying is.... its easy... seems intimidating at first, but all things technical do. what you need is python, apache and the mod_python module. you edit the configuration file to have apache start the mod_python module when apache starts. put your scripts in a folder called cgi-bin (usually) look for a line in the apache configuration file called Script-Alias. this is also where the scripts would go if you upload them to a host. almost always not the same folder where the html stuff goes.
and, yeah, the scripts whatever.py has to be on the server because they are server side scripts. server side means that all the data process is done at the server and the results are posted to the web page.
when you call print, and you are printing html, it is printing to the web browser.
in the two scripts i posted, the html form passes data to the python script, the python script takes that info (username and password) and creates a webpage that
does something based on whether or not the username and password match what the script says. the base line is that the python script actually creates html code.
another reason it did not work is the first line of the scrip.
The one that starts with a pound-bang (#!)
That is a linux thing.
check this link for how to set that line up correctly i think its C:\python24
but i am not sure. i stupidly assumed that you use linux because most servers use either linux or unix
check the apache docs for how to set up their server on your windows box. apache runs on windows too. but i am not very familliar with it. i think you
must have it installed and running to execute a cgi python script from your
own computer. maybe there is another freeware app out there,, a light server that may do you better . even if you dont host the site yourself, you can use a webserver on your home computer to test out your scripts because it is much easier to debug and re-arrange right there and then upload when you know it does exactly what you want.
Keep me posted on how its working out. if i dont know the answer, i can find it somewhere. | <urn:uuid:d5f7f841-cb50-494f-ba2b-ef3d7038ef13> | 2.84375 | 999 | Comment Section | Software Dev. | 77.644723 | 95,579,551 |
If an asteroid crashes into the Earth, it is likely to splash down somewhere in the oceans that cover 70 percent of the planets surface. Huge tsunami waves, spreading out from the impact site like the ripples from a rock tossed into a pond, would inundate heavily populated coastal areas. A computer simulation of an asteroid impact tsunami developed by scientists at the University of California, Santa Cruz, shows waves as high as 400 feet sweeping onto the Atlantic Coast of the United States.
The researchers based their simulation on a real asteroid known to be on course for a close encounter with Earth eight centuries from now. Steven Ward, a researcher at the Institute of Geophysics and Planetary Physics at UCSC, and Erik Asphaug, an associate professor of Earth sciences, report their findings in the June issue of the Geophysical Journal International.
March 16, 2880, is the day the asteroid known as 1950 DA, a huge rock two-thirds of a mile in diameter, is due to swing so close to Earth it could slam into the Atlantic Ocean at 38,000 miles per hour. The probability of a direct hit is pretty small, but over the long timescales of Earths history, asteroids this size and larger have periodically hammered the planet, sometimes with calamitous effects. The so-called K/T impact, for example, ended the age of the dinosaurs 65 million years ago.
Tim Stephens | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:d646c748-ed46-4f6b-8d30-1f6213829f94> | 4.0625 | 859 | Content Listing | Science & Tech. | 41.459789 | 95,579,571 |
The report is the most comprehensive assessment to date of the world’s wild mammals, and is the result of a five-year effort including data collected by more than 1,700 experts in 130 countries. It presents overwhelming evidence of an extinction crisis, with almost one in four mammal species at risk of disappearing forever.
Burton, Chair of the IUCN Asian Wild Cattle Specialist Group, said, “Declining mammal populations are just one tragic symptom of the increasing pressures on habitats and natural resources. In this challenging economic climate, it is vital that we do not lose sight of the benefits and services that ecosystems provide – carbon sequestration, provision of fresh water and resources, as well as aesthetic and cultural values to name but a few.”
Burton reviewed the status of Asian wild cattle and buffalo for the report. “This assessment highlights the scale of the problem facing many mammal species. The decline we have seen in wild cattle and buffalo applies across all mammals in South-East Asia,” he said. “These declines can be largely attributed to habitat loss and degradation. Urgent action is needed if we are to avoid extinctions in the near future.”
Burton said there is good reason for hope and it is not too late to act. While the results of the study indicate that at least 1,141 of the 5,487 mammals assessed are threatened with extinction, they also show that targeted conservation efforts can bring species back from the brink. Five per cent of currently threatened mammals show signs of recovery in the wild, according to the report.
Environmental organizations such as Earthwatch offer ordinary people the opportunity to help conserve threatened species worldwide.
“Volunteers help to speed up the collection of data that inform environmental management decisions, while also learning in a very practical way about the complexities of natural ecosystems. They are invaluable,” Burton said.
Key findings from the study include:
• One in four mammal species is threatened with extinction
• The terrestrial mammals in Southeast Asia are particularly at risk
• The top threats to land mammals are habitat loss and harvesting (hunting, use for medicine, fuel and other materials)
• The top threats to marine mammals include accidental mortality (bycatch, vessel strikes) and pollution
• Scientists still have a lot to learn about mammals, and targeted conservation efforts can work.
The mission of the Earthwatch Institute is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment. In 2008, Earthwatch will sponsor 130 research projects in more than 40 countries and 20 US states, making estimated volunteer field grants of $5 million. Since its founding in 1971, the organization has supported nearly 1,350 projects in 120 countries and 35 states. More than 90,000 volunteers have contributed $67 million and 11 million hours to scientific fieldwork.
IUCN, the International Union for Conservation of Nature, helps the world find pragmatic solutions to our most pressing environment and development challenges by supporting scientific research; managing field projects all over the world; and bringing governments, NGOs, the UN, international conventions and companies together to develop policy, laws and best practice.
The world's oldest and largest global environmental network, IUCN is a democratic membership union with more than 1,000 government and NGO member organizations, and almost 11,000 volunteer scientists and experts in some 160 countries. IUCN's work is supported by over 1,000 professional staff in 60 offices and hundreds of partners in public, NGO and private sectors around the world. IUCN's headquarters are located in Gland, near Geneva, in Switzerland.
About the IUCN Species Survival Commission (SSC) and Species Programme
The Species Survival Commission (SSC) is the largest of IUCN’s six volunteer commissions with a global membership of 7,000 experts. SSC advises IUCN and its members on the wide range of technical and scientific aspects of species conservation and is dedicated to securing a future for biodiversity. SSC has significant input into the international agreements dealing with biodiversity conservation.
The IUCN Species Programme supports the activities of the IUCN Species Survival Commission and individual Specialist Groups, as well as implementing global species conservation initiatives. It is an integral part of the IUCN Secretariat and is managed from IUCN’s international headquarters in Gland, Switzerland. The Species Programme includes a number of technical units covering Species Trade and Use, the Red List Unit, Freshwater Biodiversity Assessments Unit, (all located in Cambridge, UK), and the Global Biodiversity Assessment Unit (located in Washington DC, USA).
Kristen Kusek | Newswise Science News
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:900ad0cc-6591-45ea-a0e1-215773b2949b> | 3.984375 | 1,559 | Content Listing | Science & Tech. | 36.767131 | 95,579,572 |
Coastal erosion is a worldwide problem, so accurate knowledge of the factors involved in the shoreline evolution is of great importance. This study analysed three gravel beaches that were nourished with sand from the same source. However, the evolution of their shoreline was different in each case. For its analysis, different factors were studied such as the shoreline and cross-shore profile evolution, the maritime climate, sedimentology and mineralogy. From the results, it should be noted that Centro beach is the most stable with a loss of surface after the first regeneration of 12.8%, while Carrer de mar is the most instable with a loss of 20.9%. The Posidonia oceanica meadow is one of the factors that make Centro beach the most stable despite being the one that receives the most wave energy. Another factor is its mineralogy and more specifically the composition of the particles that form the sample. Thus, it is observed how the cracking or the formation of particles by different minerals with a fragile union, are factors that make the beaches behave differently against erosion. For this reason, it is concluded that in order for the shoreline to be as stable as possible over time, a previous study of the sediment to be used for nourishment is necessary, as well as its possible effect on the ecosystem, since the future shoreline evolution will depend on it.
Science of the Total Environment – Elsevier
Published: Jun 1, 2018
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“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud | <urn:uuid:2a7cb1f5-dfeb-4381-a2cf-8ce7ca37259a> | 3.515625 | 425 | Truncated | Science & Tech. | 40.184704 | 95,579,591 |
Sunday, April 1, 2007
"Ever try to shoot a slow-flying duck while standing rigidly on a fast rotating platform, and with a gun that uses bullets which curve 90° while in flight?" This question appeared in the July 1963 issue of Lab-Oratory, in an article about spacecraft trajectory design. Today, computer-generated plots and animations are used to calculate the path of spacecraft during a flyby.
The trajectory design model shown above allowed Mariner mission planners during mission development in 1967 to illustrate the orientation of the planet and calculate the the expected path of the Mariner 6 and 7 spacecraft, as well as the window of opportunity for the instruments and television cameras to operate during the flyby.
Image credit: NASA/JPL | <urn:uuid:8b3e7d63-e316-44c5-bf7a-57ad6c71564d> | 3.96875 | 152 | Personal Blog | Science & Tech. | 25.54345 | 95,579,594 |
Fusulinidae, Early Permian fusulinids
Within the Permian Word Formation, Glass Mountains. Texas, five ecological associations based on fusulinid species Intertongue complexly. The lateral ranges of species apparently relate to lateral changes of the dominant rock type in the formation and the vertical ranges reflect the expansion of newly evolved species and the gradual extinction of old species.
Of the ten species described, the following four are new: Parafusulina wildei, P. sullivanensis, P. ironensis, and Parafusulina sp. A. The geographic ranges of P. lineata, P. deliclasensis, and P. aiitimonioensis are extended to include the Word Formation in the Glass Mountains.
Contributions from the Cushman Foundation for Foraminiferal Research
Required Publisher's Statement
Permission was granted for publication of this article in Western CEDAR by the editor of the Journal of Foraminiferal Research.
Ross, Charles A., "Fusulinids from the Word Formation (Permian), Glass Mountains, Texas" (1963). Geology Faculty and Staff Publications. 59. | <urn:uuid:a4c37183-5a8a-401e-af6e-4061ef21659c> | 2.796875 | 245 | Academic Writing | Science & Tech. | 26.427375 | 95,579,598 |
The robot apocalypse has arrived ... if you happen to be a crown-of thorns starfish.
Why target these poor, innocent starfish? Well, the truth is that they aren't so innocent. When crown-of-thorns starfish population densities are under control, these beautiful creatures play a balanced role in the ecosystem of the Great Barrier Reef. But when their population booms, they can quickly become a plague, consuming coral reefs — their favorite food — with a frenzied fervor.
Unfortunately, such population booms have been happening more and more frequently along the Great Barrier Reef over the last several decades. The problem has become so ubiquitous that scientists now believe that crown-of-thorns starfish are responsible for an estimated 40 percent of the Great Barrier Reef’s total decline in coral cover.
Queensland University of Technology researchers created a killer robot in 2016 with the singular purpose of seeking out and terminating crown-of-thorns starfish, reports Techie News.
The robot, called COTSbot (short for Crown-of-Thorns Starfish robot), is a Terminator-esque killing machine. It is designed to hunt down crown-of-thorns starfish and inject them with a lethal brew of bile salts. It is capable of diving for as long as eight hours in order to deliver its poisonous mixture to as many as 200 starfish. Equipped with stereoscopic cameras for depth perception, five thrusters for stability, GPS and pitch-and-roll sensors, as well as a unique pneumatic injection arm, it is an efficient executioner. The only thing missing is an audio track proclaiming "Hasta la vista, baby" each time it vanquishes a starfish.
A smaller and mightier robot
In 2018, the same team developed a smaller version of the COTSbot called the RangerBot. It is less expensive and more agile in the water. "RangerBot will be designed to stay underwater almost three times longer than a human diver, gather vastly more data, map expansive underwater areas at scales not previously possible, and operate in all conditions and all times of the day or night," the university said on its website.
Researchers hope that by releasing a fleet of COTSbots they might restore some balance to the fragile ecology of the Great Barrier Reef, which is already under threat from pollution, tourism, coastal development and global warming.
The bots are autonomous, meaning they are capable of acting independently. For this reason especially, researchers want to make sure they are intelligent enough to identify crown-of-thorns starfish accurately. The last thing the reef needs is a fleet of assassin machines indiscriminately killing the wrong starfish species or other creatures that are healthy contributors to the ecosystem.
The robots' advanced computer vision and learning algorithm allow it to learn to target crown-of-thorns starfish more accurately. If for any reason the system struggles to identify its target, it can also record images and send them to researchers for visual confirmation.
If they are successful, the hope is to use these robots in other reefs around the world.
"The systems software architecture has been developed with task expansion in mind," Matthew Dunbabin, a professor of electrical engineering and robotics at Queensland University of Technology, told the Daily Beast. "The system can be easily upgraded with new detection modules, similar to the way plugins in apps work, without the need to change hardware."
Editor's note: This article has been updated since it was originally published in September 2015. | <urn:uuid:998c9b85-8f8a-4626-a31c-7f53a11680c5> | 3.03125 | 724 | Truncated | Science & Tech. | 37.059107 | 95,579,629 |
Wave–Particle Duality: De Broglie, Einstein, and Schrödinger
Postulation and understanding of wave–particle duality was a controversial topic from the very beginning and is closely enmeshed with the origin and development of the photoelectric effect and quantum theory. De Broglie (1924) in a seminal paper explored the reconciliation of lightquanta (used by Einstein to explain the photoelectric effect) with “the strong experimental evidence on which was based the wave theory” (p. 446). J.J. Thomson (1925), in his Structure of Light, compared the interplay between wave and particle theories of radiation to a struggle between a tiger and a shark in which each is supreme in his own element, but helpless in that of the other. Millikan (1916) provided experimental evidence for Einstein's photoelectric equation and still rejected the hypothesis of light quanta. Actually, Millikan went far beyond this by considering Einstein's hypothesis reckless, as it could not explain thoroughly established facts of interference. Millikan, however, conceded that as the photoelectric effect could not be explained by the classical theory, it may at the most need some modifications and not its rejection. Millikan's example in this case is a good indicator of how prior epistemo-logical beliefs of the scientists play an important role in the acceptance of new ideas. In the present case, even as late as 1924 Millikan believed that the classical wave theory only needed to be reinterpreted. Lakatos (1970) has explained that in the history of science, scientists frequently resist changes in the “hard core” of their theories.
The foundations of quantum physics were laid between 1896 and 1925.… Most practicing physicists have learned what little they know of the history of this period by reading textbooks written after the quantum revolution. Often texts or teachers treat the Planck radiation law, the Einstein photoelectric equation, the Bohr atom and the Compton effect in one sequence assuming that this provides an adequate background for understanding E = hv and p = hv/c. This can leave a student with less than total respect for the physicists who took so long to see the “obvious” necessity for this form of quantization. (p. 95)
KeywordsPhotoelectric Effect Historical Reconstruction Copenhagen Interpretation Particle Duality Examination Committee
Unable to display preview. Download preview PDF. | <urn:uuid:4325ec6f-48b5-43fc-80b8-3af62110bfaa> | 2.796875 | 493 | Truncated | Science & Tech. | 36.430393 | 95,579,640 |
In this comic, Black Hat has strapped James Bond to a centrifuge and claims the centrifugal force will be lethal. Bond objects that there is no such thing, but just centripetal force.
Issac Newton was the first to announce that any body will be in a stable state of motion iff (if and only if) no force is applied. No motion at all is a stable state, as is constant translation. Imagine yourself on a bicycle: if you are going fast and do not brake, only the friction of the air, tires and internals of the bike will slow you down if you are not going uphill.
Now ride your bike on a circular track, at considerable speed. You will feel the "centrifugal" force, which is actually a centripetal force that you are applying to leave your straight course. That is what moving along an orbit really is: constantly changing the direction of movement, which needs a constant force.
Black Hat argues that within a spinning inertial system, "centrifugal" force is real. Here is why: to transform equations to a subsystem, everything inherent to the system as a whole must be subtracted, including the centripetal forces, which leaves a centrifugal force on the other side of the equation. Wikipedia hints that while the centripetal force is universal, the centrifugal force is bound to the specific inertial system.
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- [James Bond is strapped to a giant wheel suspended from the ceiling. Black hat is standing next to two levers.]
- Black hat: How do you like my centrifuge, mister Bond? When I throw this lever, you will feel centrifugal force crush every bone in your body.
- [Same scene, but a closer shot.]
- Bond: You mean centripetal force. There's no such thing as centrifugal force.
- Black hat: A laughable claim, mister Bond, perpetuated by overzealous teachers of science. Simply construct Newton's laws in a rotating system and you will see a centrifugal force term appear as plain as day.
- [Closer shot, only Bond's head is visible.]
- Bond: Come now, do you really expect me to do coordinate substitution in my head while strapped to a centrifuge?
- Black hat: No, mister Bond. I expect you to die.
Are you allowed to describe a force acting upon you when you are in an accelerating reference frame? I'm pretty sure you're not. The explanation says that from bond's point of view, he is at rest. Well, sort of. If you're in an accelerating car you can tell that you're not at rest because your inertia seems to be "pulling" you backwards. There's nothing actually pulling you, though. 184.108.40.206 05:24, 30 December 2013 (UTC)
- According to general relativity, that inertial "pull" is indistinguishable from being at rest with a force being applied. In the rotating frame, this apparent force is the centrifugal force. 220.127.116.11 05:58, 4 February 2014 (UTC)
- the explanation is correct, and you can describe forces acting on you in non-inertial frames. If you take Bond to be the origin of a rotating frame of reference then the position of Bond will be (0,0,0) at all times. So in that frame of reference, Bond is at rest (not "sort of at rest, really at rest). The equation of motion for Bond is
F + Fe + Fw + Fc = ma = 0
- (F is external force, Fe is the force due to angular acceleration of the frame (relative to some inertial frame), Fw is centrifugal force and Fc is coriolis force )
- Since the sum of the three "fictious" force are nonzero, and Bond is at rest in this frame, the force F must also be non-zero. This force F is the inward push of the centrifuge. In the moving car example, you can't tell if you are accelerating or if there is a massive graviational field pulling you backwards. From your perspective the experience is identical. If you take this idea and run with it you get general relavitity18.104.22.168 11:30, 6 August 2014 (UTC)
- I believe the OP is referencing the vestibular system. This is what allows humans to feel acceleration. The actual physics at hand is regarding reference frames, not the ability of the body to detect acceleration. In regards to the question of "Are you allowed to describe a force acting upon you when you are in an accelerating reference frame?", the answer is yes. You can pick whichever reference frame you wish, but we tend to pick the one that simplifies the calculations the most.Flewk (talk) 06:44, 25 December 2015 (UTC)
"Apparent force" is the best term to use to describe centrifugal force, and could be inserted in the text to clarify. 22.214.171.124 21:14, 14 June 2018 (UTC)
- "The surface of the Earth approximates an inertial frame."
This isn't correct at all. If you're standing on Earth, you're experiencing an acceleration of 9.8 m/s^2. 126.96.36.199 00:56, 12 April 2018 (UTC)
- Actually, that is incorrect. Right now i'm in my desk chair, not accelerating. The force of gravity is cancelled out by the force my chair exerts on me to maintain this status quo. You're correct that it's not an inertial frame, but that is because the force of gravity, not some acceleration 188.8.131.52 12
- 14, 6 July 2018 (UTC) | <urn:uuid:ac3d8f0a-8a49-4eda-bcf9-68a7fdd321ab> | 3.109375 | 1,234 | Comment Section | Science & Tech. | 67.775864 | 95,579,666 |
Minnesota is known for its natural beauty and iconic local accent, but not so much for abundant sunlight. In fact, Minnesota tends to be generally overcast, so it makes sense that most people don't immediately think of Minnesota in relation to solar energy. But the fact is, though Minnesota doesn't produce nearly as many total watts of solar power as sunnier states like Arizona or California, it does lead the U.S. in one particular kind of solar power: community solar.
According to Energy Sage, the term "community solar" describes any solar energy program in which a group of residents can opt to share solar energy from one network, splitting clean energy costs among themselves. Such programs, if efficiently run, have the potential to save consumers a substantial amount in energy costs over time.
The popularity of such programs has soared in Minnesota since 2013, when the Solar Energy Jobs Act was signed into law. Among other changes to Minnesota's energy policies, the Solar Energy Jobs Act made it possible for community solar to operate with no cap. It was this simple change that secured Minnesota's lead in successful community solar programs in the United States.
Toward the end of 2016, only about 120 total megawatts existed in community solar projects across the U.S., according to Ozy. Now, in Minnesota, 478 community solar projects are getting ready to launch, which will lead to a total of around 1,000 megawatts being produced. Many of these new projects have been introduced by state utility Xcel, including two of the largest in the state: the North Star and Aurora Solar projects.
Combined, Minnesota's community solar programs ultimately helped to increase the state's solar energy output 12 times over from 2015 to 2016--a monumental increase unlike anything seen in other states.
If there is anything to learn from the monumental solar energy boom Minnesota has experienced since 2013, it may well be that community-based clean energy has the potential to be popular. This is especially true when states do all they can to make such projects affordable for average consumers, as Minnesota has striven to do.
The state is working on a "valued solar rate," to make solar energy more accessible, a far cry from states where residents must pay a premium to access clean energy. The idea that average residents should be able to access clean energy seems to be at the heart of the changes rapidly taking place in Minnesota.
Recently, St. Paul, Minneapolis and 29 other Minnesota localities pledged together to purchase 33 megawatts of solar subscriptions. Even government groups and schools are jumping on board, purchasing 25-year energy contracts in order to save money on long term energy costs. Sara Bergan, an energy law attorney for Pacific Northwest firm Stoel Rives, told Ozy that the principle behind community solar programs is that "in theory, it expands access to solar development to everybody." It's a simple concept, but one that has fueled great success and change in Minnesota, thus far, with no signs of slowing down.
When it comes to plastic bags, one question persists: Are they recyclable, or not?
Tsumoru Shintake has invented a turbine that converts wave energy into clean electricity currently powering hotels.
This town in Long Island is using leftover shells from local restaurants to build a "living" barrier reef. | <urn:uuid:24cd2122-45bc-4d51-a834-f7e03cc750af> | 2.609375 | 671 | News Article | Science & Tech. | 37.06844 | 95,579,689 |
Memory Allocation: block-structured language
- The block is a sequence of statements containing the local data and declarations which are enclosed within the delimiters.
- Similarly, The delimiters mark the beginning and the end of the block. There can be nested blocks for ex: block B2 can be completely defined within the block B1.
- A block-structured language uses dynamic memory allocation.
- Moreover, Finding the scope of the variable means checking the visibility within the block
- Following are the rules used to determine the scope of the variable:
1. Variable X accessed within the block B1 if it can be accessed by any statement situated in block B1.
2. Variable X accessed by any statement in block B2 and block B2 situated in block B1.
- Similarly, There are two types of variable situated in the block-structured language
1. Local variable
2. Non-local variable
To understand local and non-local variable consider the following example
- Procedure Local variables Non local variables
- Variables x, y and z local variables to procedure A but those are non-local to block B and C because this variable not defined locally within the block B and C but are accessible within these blocks.
- Automatic dynamic allocation implemented using the extended stack model.
- Memory Allocation: block-structured language
- Moreover, Each record in the stack has two reserved pointers instead of one.
- Similarly, Each stack record accommodates the variable for one activation of a block, which we call an activation record (AR).
- The first reserved pointer in block’s AR points to the activation record of its dynamic parent.
This called dynamic pointer and the address 0 (ARB).
- Moreover, The dynamic pointer used for de-allocating an AR.
Following example shows memory allocation for the program given below.
- Similarly, Access to non local variable implemented using the second reserved pointer in AR. This pointer which the address 1 (ARB) called the static pointer. | <urn:uuid:a4ecd084-30f5-439e-899c-471d1c122a27> | 3.484375 | 421 | Documentation | Software Dev. | 39.428007 | 95,579,700 |
Photochemical Holeburning and Stark Spectroscopy of Photosynthetic Reaction Centers
The initial step in photosynthesis involves photoexcitation of a primary electron donor and electron transfer to a primary electron acceptor. These processes take place in a membrane-protein complex called the photosynthetic reaction center (RC). The best characterized RCs have been isolated from the photosynthetic bacteria R. spheroides (R-26 mutant) and R. viridis. In both species, the complexes consist of three proteins each of approximate molecular weight 25–30kDa, four bacteriochlorophylls (BChls), two bacteriopheophytins (BPheo, BChl in which two H atoms replace the central Mg atom), two quinones and one non-heme iron . In R. spheroides the pigments are a-type BChl, whereas in R. viridis the pigments are b-type. The prosthetic groups are embedded in the RC protein in vectorial fashion across the membrane, as shown by x-ray crystallography (Fig. 1) [2–4]. Combined with extensive earlier spectroscopic studies, the x-ray structure identifies the functional components with specific structural elements: the primary electron donor, often called P or the special pair, is identified as the strongly-coupled BChl dimer; the intermediate acceptor, often called I, is identified as the BPheo on the L-side; and the primary quinone (0A, ubiquinone in R. Spheroides, menaquinone in R. Viridis) is the quinone on the L-side. The function of the BChl situated between the dimeric electron donor and the BPheo acceptor is uncertain, though it is certainly involved in mediating electron transfer from the excited state of P to I. The role of the chromophores on the M-side of the RC, which are related to those on the functional L-side by a C2 axis running vertically through the Fe, is unknown. Recent structural work on the R. spheroides RC suggests that the gross features of its structure are very similar to those of R. viridis [5,6].
KeywordsTransition Dipole Moment Special Pair Photosynthetic Reaction Center Excited State Lifetime Primary Electron Donor
Unable to display preview. Download preview PDF.
- 1.S.G. Boxer: Biochim. Biophys. Acta 726, 2625–292 (1983).Google Scholar
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For the last 20 years, Germany has been working towards cleaner, renewable energy sources for their country. The New York Times reports that the nation has spent $2oo billion in that time. That obviously sounds like an enormous amount of money, but it has created huge dips in the cost of energy for consumers. The investments are also paying off in terms of crossing of their list of energy goals.
Climate Action Programme reports that data from the Association of Energy and Water Industries (BDEW), which show that Germany has grown its renewable electricity generation a record 33 percent in 2017, from 29 percent share in 2016.
Stefan Kapferer, Chairman of the BDEW, believes the numbers show there's been a sea-change in the use of renewable power.
"The figures show impressively that there is already an accelerated shift in power generation from CO2-intensive to low-carbon and almost CO2-free energy sources," said Kapferer. “The energy industry is clearly on course with regard to energy and climate targets: our industry is able to reduce CO2 emissions by 40 percent by 2020 compared to 1990."
Germany committed to "Energiewende" or the switch to renewable energy in 2010, setting a target of 60 percent renewable energy use by 2050. They have another 27 percent to go.
Photo @lucalocatelliphoto It is impressive to fly over a 'forest' of wind turbines in the middle of the North Sea, 54 km from the German coast. Some 25 wind farms like this are under construction. Hundreds of people are climbing up every day on those wind turbines, with their height of 147 meters, which produce the renewable energy of the future. In 2014 Germany only 0.2 percent of the energy was produced with Off-shore Wind and the ambitious goal is to reach 26 percent by 2020. This is the German Energy Transition, documented on assignment for @natgeo. Follow me to see more about my project about The Energy Transition for natgeo @lucalocatelliphoto @instituteartist #climatechange #energytransition #renewableenergy #green #energy #windturbine #wind #northsea #energiewende #natgeo #renewable #conservation
One of the biggest challenges is separating the country from its use of lignite, which is sometimes called "brown coal," which still accounts for almost 23 percent of the country's power supply. However, Kapferer seems optimistic, telling journalists that reduction is “in full swing," adding that “nobody is investing in hard coal plants any longer”.
The other challenge to a wind energy plan is developing battery technology that can balance the erratic power generation of wind turbines.
As the NYT reports, folks were actually paid to consume energy around the holidays as offices and other buildings were shut down this year. How windy it gets cannot be controlled, so there are times when these renewable sources create an enormous amount of energy, but battery packs are not able to store that power. Working out a way to encourage consumers to do things like run their washing on a windy day with price cuts is one suggestion for how to balance the stress on the electric grid. But the confusion around how to deal with this excess and drought proves Kapferer is right about one thing—the possibilities in renewable energy sources are coming at us fast, and we've got to catch up.
Researchers from marine life advocates Oceana have discovered a surprising new world under the sea near Sicily.
Sweden's aggressive target of generating over 40 terawatt-hours of renewable energy by 2030 could be reached nearly a decade early. A massive amount of wind power projects could hit a snag in market value with subsidies, but SWEA could push to close those up by the end of the year.
Starbucks is ramping up its sustainability efforts with a plan to eradicate the use of plastic straws in its assembly line. | <urn:uuid:b6db42c4-2363-4df2-b46e-18c97ad79683> | 3.234375 | 809 | News Article | Science & Tech. | 37.784468 | 95,579,704 |
The infamous ozone hole over Antarctica, first discovered in the 1980s, is a year-round fixture, with a twin over the North Pole. The ultraviolet (UV) radiation falling on mid-latitude cities like Washington, D.C., is strong enough to cause sunburn in just five minutes. DNA-mutating UV radiation is up 650 percent, with likely harmful effects on plants, animals and human skin cancer rates.
Such is the world we would have inherited if 193 nations had not agreed to ban ozone-depleting substances, according to atmospheric chemists at NASA's Goddard Space Flight Center, Greenbelt, Md., Johns Hopkins University, Baltimore, and the Netherlands Environmental Assessment Agency, Bilthoven.
Led by Goddard scientist Paul Newman, the team simulated "what might have been" if chlorofluorocarbons (CFCs) and similar chemicals were not banned through the treaty known as the Montreal Protocol. The simulation used a comprehensive model that included atmospheric chemical effects, wind changes, and radiation changes. The analysis has been published online in the journal Atmospheric Chemistry and Physics.
"Ozone science and monitoring has improved over the past two decades, and we have moved to a phase where we need to be accountable," said Newman, who is co-chair of the United Nations Environment Programme's Scientific Assessment Panel to review the state of the ozone layer and the environmental impact of ozone regulation. "We are at the point where we have to ask: Were we right about ozone? Did the Montreal Protocol work? What kind of world was avoided by phasing out ozone-depleting substances?"
Ozone is Earth's natural sunscreen, absorbing and blocking most of the incoming UV radiation from the sun and protecting life from DNA-damaging radiation. The gas is naturally created and replenished by a photochemical reaction in the upper atmosphere where UV rays break oxygen molecules (O2) into individual atoms that then recombine into three-part molecules (O3). As it is moved around the globe by upper level winds, ozone is slowly depleted by naturally occurring atmospheric gases. It is a system in natural balance.
But chlorofluorocarbons -- invented in 1928 as refrigerants and as inert carriers for chemical sprays -- upset that balance. Researchers discovered in the 1970s and 1980s that while CFCs are inert at Earth's surface, they are quite reactive in the stratosphere (10 to 50 kilometers altitude, or 6 to 31 miles), where roughly 90 percent of the planet's ozone accumulates. UV radiation causes CFCs and similar bromine compounds in the stratosphere to break up into elemental chlorine and bromine that readily destroy ozone molecules. Worst of all, such ozone depleting substances can reside for several decades in the stratosphere before breaking down.
In the 1980s, ozone-depleting substances opened a wintertime "hole" over Antarctica and opened the eyes of the world to the effects of human activity on the atmosphere. By 1987, the World Meteorological Organization and United Nations Environment Program had brought together scientists, diplomats, environmental advocates, governments, industry representatives, and non-governmental organizations to forge an agreement to phase out the chemicals. In January 1989, the Montreal Protocol went into force, the first-ever international agreement on regulation of chemical pollutants.
"The regulation of ozone depleting substances was based upon the evidence gathered by the science community and the consent of industry and government leaders," Newman noted. "The regulation pre-supposed that a lack of action would lead to severe ozone depletion, with consequent severe increases of solar UV radiation levels at the Earth's surface."
In the new analysis, Newman and colleagues "set out to predict ozone losses as if nothing had been done to stop them." Their "world avoided" simulation took months of computer time to process.
The team started with the Goddard Earth Observing System Chemistry-Climate Model (GEOS-CCM), an earth system model of atmospheric circulation that accounts for variations in solar energy, atmospheric chemical reactions, temperature variations and winds, and other elements of global climate change. For instance, the new model accounts for how changes in the stratosphere influence changes in the troposphere (the air masses near Earth's surface). Ozone losses change the temperature in different parts of the atmosphere, and those changes promote or suppress chemical reactions.
The researchers then increased the emission of CFCs and similar compounds by 3 percent per year, a rate about half the growth rate for the early 1970s. Then they let the simulated world evolve from 1975 to 2065.
By the simulated year 2020, 17 percent of all ozone is depleted globally, as assessed by a drop in Dobson Units (DU), the unit of measurement used to quantify a given concentration of ozone. An ozone hole starts to form each year over the Arctic, which was once a place of prodigious ozone levels.
By 2040, global ozone concentrations fall below 220 DU, the same levels that currently comprise the "hole" over Antarctica. (In 1974, globally averaged ozone was 315 DU.) The UV index in mid-latitude cities reaches 15 around noon on a clear summer day (a UV index of 10 is considered extreme today.), giving a perceptible sunburn in about 10 minutes. Over Antarctica, the ozone hole becomes a year-round fixture.
In the 2050s, something strange happens in the modeled world: Ozone levels in the stratosphere over the tropics collapse to near zero in a process similar to the one that creates the Antarctic ozone hole.
By the end of the model run in 2065, global ozone drops to 110 DU, a 67 percent drop from the 1970s. Year-round polar values hover between 50 and 100 DU (down from 300-500 in 1960). The intensity of UV radiation at Earth's surface doubles; at certain shorter wavelengths, intensity rises by as much as 10,000 times. Skin cancer-causing radiation soars.
"Our world avoided calculation goes a little beyond what I thought would happen," said Goddard scientist and study co-author Richard Stolarski, who was among the pioneers of atmospheric ozone chemistry in the 1970s. "The quantities may not be absolutely correct, but the basic results clearly indicate what could have happened to the atmosphere. And models sometimes show you something you weren't expecting, like the precipitous drop in the tropics."
"We simulated a world avoided," said Newman, "and it's a world we should be glad we avoided."
The real world of CFC regulation has been somewhat kinder. Production of ozone-depleting substances was mostly halted about 15 years ago, though their abundance is only beginning to decline because the chemicals can reside in the atmosphere for 50 to 100 years. The peak abundance of CFCs in the atmosphere occurred around 2000, and has decreased by roughly 4 percent to date.
Stratospheric ozone has been depleted by 5 to 6 percent at middle latitudes, but has somewhat rebounded in recent years. The largest recorded Antarctic ozone hole was recorded in 2006.
"I didn't think that the Montreal Protocol would work as well as it has, but I was pretty naive about the politics," Stolarski added. "The Montreal Protocol is a remarkable international agreement that should be studied by those involved with global warming and the attempts to reach international agreement on that topic."
Sarah DeWitt | EurekAlert!
Further reports about: > Antarctic Predators > Antarctica > CFC > DNA-mutating UV radiation > Earth's natural sunscreen > Environment > UV radiation > chemical pollutants > chemical reaction > chlorofluorocarbons > environmental impact of ozone regulation > infamous ozone hole > oxygen molecule > oxygen molecules > ozone > ozone hole > ozone-depleting substances > prodigious ozone levels > three-part molecules > ultraviolet radiation
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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12.07.2018 | Event News
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I would probably say instead that traditional thermodynamics equations work easiest and best for studying/describing systems near equilibrium (which would be above and below star formation)- it gets quite complicated quite fast and they are much harder to study in systems that are far from equilibrium/driven by powerful external energy sources. They do ‘uniformly apply everywhere’ but it is just very difficult to apply the equations in far from equilibrium systems.
In his most recent papers, many of the simulated systems did tend to just dissipate out to ‘nothingness’ so to speak. But for some initial settings, the system ended up evolving to fix points far from equilibrium, vigorously cycling through chemical reactions by harvesting the maximum energy possible from the environment-living creatures also maintain steady states of extreme forcing like this. England’s work show that it can arise basically right away, without extremely long wait times. Ultimately what he’s showing is that as long as you can harvest energy from your environment, order will spontaneously arise and self-tune. There’s a lot more to be figured out here but it is very interesting to say the least. | <urn:uuid:0c974428-1703-499b-83e6-7e6039900346> | 2.828125 | 234 | Comment Section | Science & Tech. | 27.820464 | 95,579,729 |
about this item
This book is intended as a historical and critical study on the origin of the equations of motion as established in Newton's Principia. The central question that it aims to answer is whether it is indeed correct to ascribe to Galileo the inertia principle and the law of falling bodies. In order to accomplish this task, the study begins by considering theories on the motion of bodies from classical antiquity, and especially those of Aristotle. The theories developed during the Middle Ages and the Renaissance are then reviewed, with careful analysis of the contributions of, for example, the Merton and Parisian Schools and Galileo’s immediate predecessors, Tartaglia and Benedetti. Finally, Galileo’s work is examined in detail, starting from the early writings. Excerpts from individual works are presented, to allow the texts to speak for themselves, and then commented upon. The book provides historical evidence both for Galileo's dependence on his forerunners and for the major breakthroughs that he achieved. It will satisfy the curiosity of all who wish to know when and why certain laws have been credited to Galileo.
Sub-Genre: Astronomy, Physics, Mechanics / General
Publisher: Springer Verlag
Author: Dino Boccaletti
Street Date: August 28, 2015
Item Number (DPCI): 248-03-8672 | <urn:uuid:04fa0864-a6f7-4d8b-b321-36c79b6f78d5> | 2.9375 | 272 | Product Page | Science & Tech. | 28.314107 | 95,579,734 |
Facts Summary: The Banded White-eye (Zosterops vellalavella) is a species of concern belonging in the species group "birds" and found in the following area(s): Solomon Islands. This species is also known by the following name(s): Belted White-eye.
Banded White-eye Facts Last Updated: January 1, 2016
To Cite This Page:
Glenn, C. R. 2006. "Earth's Endangered Creatures - Banded White-eye Facts" (Online).
Accessed 7/18/2018 at http://earthsendangered.com/profile.asp?sp=13522&ID=4.
Need more Banded White-eye facts?
10 Unusually White Creatures You'll Probably Never See in Real Life
Creatures with albinism and leucism are beautiful and rare animals. They have all the characteristics of others of their species except they are white in color. The lack of melanin generally results in the animal looking bleached all over, appearing white or pink. It happens in many animals ranging from squirrels to whitetail deer. Here are ten incredible and rare, white-colored creatures that you'll probably never see in real life. | <urn:uuid:80c01813-8719-4f95-8fef-feb6fd18714d> | 3.53125 | 257 | Knowledge Article | Science & Tech. | 58.450345 | 95,579,736 |
The assessment and prevention of these risks require more effective measures than at present. The Finnish-coordinated project of the joint Baltic Sea Research Programme is seeking out ways of managing risks and creating a new model to support environmental decision-making.
The model that is under development could be used in the assessment of the pros and cons of different alternative decisions, by utilising multidisciplinary and multi-objective information. “The multi-objectivity concerns the fact that risks can’t be eliminated by one factor alone.
The minimisation of biological risks would mean an end to all human activity in the Gulf of Finland. It must be possible to find an acceptable risk level and to achieve it cost-effectively,” says Professor Sakari Kuikka of the University of Helsinki, who is in charge of the project.
This project being run by Professor Kuikka is one of the four projects coordinated by Finland in the BONUS research programme. In total, 16 multidisciplinary international research projects are being funded in the programme. Research funding organisations from the nine Baltic Sea countries are behind this new Baltic Sea Research Programme. Total project funding will be approximately 60 million euros between 2010 and 2016. The EU Commission is also taking part in the funding. The Finnish funding organisation is the Academy of Finland.
The environmental decision model for the Gulf of Finland gathers together available scientific information using probability calculation. It combines the risks stemming from different fields: fishing, eutrophication, oils spills, dioxins and climate change.
According to Kuikka, this research project will enable more effective scientific learning by producing tools by which old and new information can be combined. This approach is based on probability models already developed by the research team, on the re-analysis of the wealth of existing materials and on published articles.
Professor Kuikka considers it important that the so-called Bayesian calculation methods available allow the gradual accumulation of information, i.e. correspond to the process of scientific learning.
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
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A Forward Model is a model that takes parameters and produces observable values. Thus the model plus a set of parameters constitutes a prediction. A Backward Model is a model that works in the reverse direction: given values observed, produces parameters, which could be characteristics not subject to observation.
For example, a backward model might be a means of calculating the Abundances of constituents of an Extra Solar Planet's Atmosphere from Transmission Spectroscopy data, whereas a forward model would take assumptions of the abundances and calculate what the transmission Spectroscopy data would be.
Backward models often can be devised using Markov-Chain Monte Carlo (MCMC) methods. Also, a slow backward model can be devised from a forward model through searching the parameter space. A backward model that is efficiently calculable can, in turn, be used in analysis involving many cases of observed data, e.g., from Photometric Surveys of many stars. | <urn:uuid:c7eda54e-437c-48b8-b376-a9e2092c4cea> | 3.328125 | 190 | Knowledge Article | Science & Tech. | 32.180936 | 95,579,767 |
Which element(s) has an outermost electron that could be described by the following quantum numbers:
(3,1,-1,+1/2) ?© BrainMass Inc. brainmass.com July 20, 2018, 10:25 pm ad1c9bdddf
Interpreting the quantum numbers:
Qunatum numbers are given in the following order:
1. Principal quantum number (n) - describes the energy level in which the electron can be found. Has a whole number, with positive value, from 1 to 7.
2. Azimuthal quantum number (l) - describes the shape of the orbital. Can ... | <urn:uuid:f70e8946-ce02-493a-b0da-a82786b8ee46> | 3.078125 | 137 | Tutorial | Science & Tech. | 75.843834 | 95,579,772 |
Although the media has done a great job of covering this up, the inconvenient fact is that all seven glaciers on California’s Mount Shasta are growing. This includes Whitney Glacier, the state’s largest.
Yes, growing. Not melting.
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Not only are Mt. Shasta’s glaciers growing, two have nearly doubled in size.
Both the Hotlum and Wintun Glaciers have nearly doubled in size since 1950, says this article on Wikipedia. The Bolam Glacier has increased by half, while the Whitney and Konwakiton Glaciers have grown by a third.
Scientists first became aware of these growing California glaciers in 2002, and I began writing about them in 2003. Now, eight years later, most media outlets still refuse to acknowledge that these glaciers are growing.
Read More at Canada Free Press by Robert Felix, Canada Free Press
Facebook has greatly reduced the distribution of our stories in our readers' newsfeeds and is instead promoting mainstream media sources. When you share to your friends, however, you greatly help distribute our content. Please take a moment and consider sharing this article with your friends and family. Thank you. | <urn:uuid:9ca4b089-34c3-4c0c-bb1d-651645e2d035> | 2.609375 | 244 | Truncated | Science & Tech. | 52.1325 | 95,579,780 |
The Radio Jove Mystery
Well, as I written before here and here, I am currently working on radio astronomy. I had been putting off working on it for almost 2 years until last summer when things finally picked up some pace. Well, atleast in one sense.
The first thing any amateur astronomer interested in pursuing radio astronomy and building a radio telescope should know about is The Radio Jove project. It is an amateur radio astronomy project backed by NASA based on a dipole antenna capable enough to observe radio emissions from jupiter and the sun. As for why this particular frequency was chosen instead of others, i have no answer. The sun is a black body and emits a continuum radio spectrum and jupiter has an emission peak at 20.1MHz. You can read up more about the emissions processes on wiki or google for the, that is not the topic for this blog post.
Now, looking at the material from the project site, I estimate that the original team stopped updating the manuals after version 1.2, the update which involves interferometry. So, when I started pursuing the project seriously, I started hitting some road blocks.
Before anything more, let me brief you on my project.
is pretty much what my project is.
So, now let's look at the different components of the experiment. The antenna is the part of the setup which receives the signal. for now let's assume that we have an antenna and we are getting some kind of signal from it. It is to be noted that while there are different kinds of antenna, the Radio Jove experiment uses a Dipole Antenna. And dipole antenna are designed to pick up specific wavelengths (n*lambda). So, the dipole antenna itself acts as a Low Frequency Noise Block or an out of range noise block in a sense. But then, as the circuit mentions, we have a additional bandpass filter (usually just an RC tank circuit). And what a band pass filter circuit does is amplify the signal of the frequency band selected and attenuate the out of band frequency signals.
And as you will understand later on, i intend to observe the radio continuum and not just the specific 20.1MHz frequency, which is what the radio jove project is designed to observe.
Moving further, the Low Noise Amplifier (LNA) is necessary as the input voltages are of the order microVolts @ 20MHz and we (students and amateurs) usually dont have the equipment to measure microVolt variations in a signal (yes, the radio signals from outer space are very very weak). And the twist here is the frequency of observation. There are commercially available LNAs for the frequency ranges of 500MHz to 4GHz as this is the commercial telecommunication band. So, for the sake of the project, either construct an LNA yourself or scour the internet for others who have done similar radio astronomy projects and ask them for advice.
Now, let me introduce you to the circuit mentioned in the Radio Jove project and show you a couple of holes (no, not the electrical meaning for holes, the metaphorical meaning).
IC1 - SA602AN (modulator)
IC2, IC3 - LM 387 (audio pre-amp) - as the circuit mentions
Loosely talking, the LM387 part of the circuit, after the SA602AN is the audio pre-ampifier part of the circuit which is used for data acquisition and analysis. I will elaborate on that later on but for now let's look at the part of the circuit before that i.e IC1. Well, you see, SA602AN has been obsolete for over an year now and finding a perfect replacement for it is almost impossible, from what my search results tell me. The website still says that the circuit works and that we can order kits and make the circuit ourselves. Maybe they stock piled or maybe they update the circuit without making corrections in the manual, i dont know but the basic point is i cannot build this circuit right now.
Which is the reason why i need to make my own LNAs.
Modulation and low pass filters make sense because we want to selectively tune to and study the frequency around 20.1 MHz (which is what the radio jove is designed for) and attenuate the rest of the frequencies. This part of the circuit, i still haven't been able to figure out and also dont have the need for currently. My current method for data retrieval doesn't depend on the frequency of the signal i.e it does not need to be modulated to the ~10KHz range (as the laptop's sound card can only acquire signals till ~100KHz and the laptop's sound card is what we use to acquire the signal from the antenna. wipe that expression off your face and read on)
Then comes the other interesting part, data retrieval. Using an audio pre amp, we push this data into a computer's audio jack and as the signal has already been modulated from MHz to KHz, the sound card of any PC will be able to decipher it. And using relevant software on the PC, you should be able to process the signal, check for noise, harmonic distortion and what not. But I was doubtful as to how scientifically accurate this method was. I did not know how much noise the audio pre-amps (LM387) added, how much of a noise the PC sound card added. So, I came up a different method for data retrieval, albeit a bit more complicated and intensive, a more scientifically one I feel. And i've tried it with simulated data and the system works perfectly fine. Now, I need to compare this method of acquisition to the method mentioned in the Radio Jove Project because i also need to look for a universal method, not just one which is scientifically accurate.
Well, obviously the guys from NASA had a good intention in mind when they started this project, put up all of the material online. If you are an amateur radio astronomer, the radio jove -project is still one of the best way to start and understand the basics of Radio Astronomy.
But alas, without regular updates, nothing will work forever...
There is one small question i would like to address now. The question of the dipole antenna used to acquire the signal, which we've been trying to process all this while. So, as i mentioned, a dipole antenna is designed for specific wavelengths and can only pickup those frequencies. So, it does make sense to design the circuit around this fact. But as i mentioned, i intend to look at the radio continuum in the 1-50MHz range. So, i can't use the dipole antenna!
Then comes the more puzzling question regarding the antenna mentioned in the project. It is mentioned in the manual that the height at which the antenna should be mounted is dependent on the latitude of the place and on the season of the year, which is quite baffling to start with. Well, given, im not exactly an electical engineer, but even I know that this statement sounds absurd at the first time (I still havent seen a meaningful reason behind this yet). And well, just to be sure, I inquired with a professor from the electrical department here and he gave me the strangest look ever, sent me back with material to read up and asked me to do more ground work before coming up with such questions again :d...
I have mailed the relevant people at Radio Jove (the mailing list) hoping for a reply about these and quite a few other doubts I have. No reply as of yet. I'll try one last time and move on to bothering someone who'd reply…
So, as of now, im working on a couple of things -
- In search of good LNAs that work in the 1-50MHz range. And just to get things rolling, Im studying the frequency dependent response of regular Op-amp amplifier circuits, a circuit based on a FET. The experiment is to check the response of circuits which have gain in the range of ~40 dB and study the circuit's frequency response. perform noise analysis and harmonic distortion studies. I'll tell you guys how that works out...
- Study the signal retrieved using the LM387s (audio pre-amps) and compare this signal to that retrieved using my own method, to see if the audio pre-amp method is any good to perform scientific studies.
- Construct the receiver and hope for a signal
I'll keep you guys updated.
Until next time ...
PS - if you guys know anything about radio astronomy, comment here or mail me or ping me or anything! I want to get in touch with you! | <urn:uuid:bac07977-413e-4f61-bee3-85534475f313> | 3.140625 | 1,779 | Personal Blog | Science & Tech. | 57.34728 | 95,579,791 |
In mathematics, the covariant derivative is a way of specifying a derivative along tangent vectors of a manifold. Alternatively, the covariant derivative is a way of introducing and working with a connection on a manifold by means of a differential operator, to be contrasted with the approach given by a principal connection on the frame bundle – see affine connection. In the special case of a manifold isometrically embedded into a higher-dimensional Euclidean space, the covariant derivative can be viewed as the orthogonal projection of the Euclidean derivative along a tangent vector onto the manifold's tangent space. In this case the Euclidean derivative is broken into two parts, the extrinsic normal component and the intrinsic covariant derivative component.
In physics, the covariant derivative is the derivative that under a general coordinate transformation transforms covariantly, that is, linearly via the Jacobian matrix of the coordinate transformation.
This article presents an introduction to the covariant derivative of a vector field with respect to a vector field, both in a coordinate free language and using a local coordinate system and the traditional index notation. The covariant derivative of a tensor field is presented as an extension of the same concept. The covariant derivative generalizes straightforwardly to a notion of differentiation associated to a connection on a vector bundle, also known as a Koszul connection.
Historically, at the turn of the 20th century, the covariant derivative was introduced by Gregorio Ricci-Curbastro and Tullio Levi-Civita in the theory of Riemannian and pseudo-Riemannian geometry. Ricci and Levi-Civita (following ideas of Elwin Bruno Christoffel) observed that the Christoffel symbols used to define the curvature could also provide a notion of differentiation which generalized the classical directional derivative of vector fields on a manifold. This new derivative – the Levi-Civita connection – was covariant in the sense that it satisfied Riemann's requirement that objects in geometry should be independent of their description in a particular coordinate system.
It was soon noted by other mathematicians, prominent among these being Hermann Weyl, Jan Arnoldus Schouten, and Élie Cartan, that a covariant derivative could be defined abstractly without the presence of a metric. The crucial feature was not a particular dependence on the metric, but that the Christoffel symbols satisfied a certain precise second order transformation law. This transformation law could serve as a starting point for defining the derivative in a covariant manner. Thus the theory of covariant differentiation forked off from the strictly Riemannian context to include a wider range of possible geometries.
In the 1940s, practitioners of differential geometry began introducing other notions of covariant differentiation in general vector bundles which were, in contrast to the classical bundles of interest to geometers, not part of the tensor analysis of the manifold. By and large, these generalized covariant derivatives had to be specified ad hoc by some version of the connection concept. In 1950, Jean-Louis Koszul unified these new ideas of covariant differentiation in a vector bundle by means of what is known today as a Koszul connection or a connection on a vector bundle. Using ideas from Lie algebra cohomology, Koszul successfully converted many of the analytic features of covariant differentiation into algebraic ones. In particular, Koszul connections eliminated the need for awkward manipulations of Christoffel symbols (and other analogous non-tensorial) objects in differential geometry. Thus they quickly supplanted the classical notion of covariant derivative in many post-1950 treatments of the subject.
The covariant derivative is a generalization of the directional derivative from vector calculus. As with the directional derivative, the covariant derivative is a rule, , which takes as its inputs: (1) a vector, u, defined at a point P, and (2) a vector field, v, defined in a neighborhood of P. The output is the vector , also at the point P. The primary difference from the usual directional derivative is that must, in a certain precise sense, be independent of the manner in which it is expressed in a coordinate system.
A vector may be described as a list of numbers in terms of a basis, but as a geometrical object a vector retains its own identity regardless of how one chooses to describe it in a basis. This persistence of identity is reflected in the fact that when a vector is written in one basis, and then the basis is changed, the components of the vector transform according to a change of basis formula. Such a transformation law is known as a covariant transformation. The covariant derivative is required to transform, under a change in coordinates, in the same way as a basis does: the covariant derivative must change by a covariant transformation (hence the name).
In the case of Euclidean space, one tends to define the derivative of a vector field in terms of the difference between two vectors at two nearby points. In such a system one translates one of the vectors to the origin of the other, keeping it parallel. With a Cartesian (fixed orthonormal) coordinate system "keeping it parallel" amounts to keeping the components constant. Thus is obtained the simplest example: a covariant derivative which is obtained by taking the ordinary directional derivative of the components in the direction of the displacement vector between the two nearby points.
In the general case, however, one must take into account the change of the coordinate system. For example, if the same covariant derivative is written in polar coordinates in a two dimensional Euclidean plane, then it contains extra terms that describe how the coordinate grid itself "rotates". In other cases the extra terms describe how the coordinate grid expands, contracts, twists, interweaves, etc. In this case "keeping it parallel" does not amount to keeping components constant under translation.
Consider the example of moving along a curve γ(t) in the Euclidean plane. In polar coordinates, γ may be written in terms of its radial and angular coordinates by γ(t) = (r(t), θ(t)). A vector at a particular time t (for instance, the acceleration of the curve) is expressed in terms of , where and are unit tangent vectors for the polar coordinates, serving as a basis to decompose a vector in terms of radial and tangential components. At a slightly later time, the new basis in polar coordinates appears slightly rotated with respect to the first set. The covariant derivative of the basis vectors (the Christoffel symbols) serve to express this change.
In a curved space, such as the surface of the Earth (regarded as a sphere), the translation is not well defined and its analog, parallel transport, depends on the path along which the vector is translated.
A vector e on a globe on the equator at point Q is directed to the north. Suppose we parallel transport the vector first along the equator until at point P and then (keeping it parallel to itself) drag it along a meridian to the pole N and (keeping the direction there) subsequently transport it along another meridian back to Q. Then we notice that the parallel-transported vector along a closed circuit does not return as the same vector; instead, it has another orientation. This would not happen in Euclidean space and is caused by the curvature of the surface of the globe. The same effect can be noticed if we drag the vector along an infinitesimally small closed surface subsequently along two directions and then back. The infinitesimal change of the vector is a measure of the curvature.
- The definition of the covariant derivative does not use the metric in space. However, for each metric there is a unique torsion-free covariant derivative called the Levi-Civita connection such that the covariant derivative of the metric is zero.
- The properties of a derivative imply that depends on an arbitrarily small neighborhood of a point p in the same way as e.g. the derivative of a scalar function along a curve at a given point p depends on an arbitrarily small neighborhood of p.
- The information on the neighborhood of a point p in the covariant derivative can be used to define parallel transport of a vector. Also the curvature, torsion, and geodesics may be defined only in terms of the covariant derivative or other related variation on the idea of a linear connection.
Informal definition using an embedding into Euclidean spaceEdit
Suppose a (pseudo) Riemann manifold , is embedded into Euclidean space via a twice continuously-differentiable (C2) mapping such that the tangent space at is spanned by the vectors
and the scalar product on is compatible with the metric on M:
(Since the manifold metric is always assumed to be regular, the compatibility condition implies linear independence of the partial derivative tangent vectors.)
For a tangent vector field, , one has
The last term is not tangential to M, but can be expressed as a linear combination of the tangent space base vectors using the Christoffel symbols as linear factors plus a vector normal to the tangent space:
The covariant derivative , also written , is defined as just a tangential portion of the usual derivative:
In the case of the Levi-Civita connection, is required to be orthogonal to tangent space, so
On the other hand,
implies (using the symmetry of the scalar product and swapping the order of partial differentiations)
and yields the Christoffel symbols for the Levi-Civita connection in terms of the metric:
For a very simple example that captures the essence of the description above, draw a circle on a flat sheet of paper. Travel around the circle at a constant speed. The derivative of your velocity, your acceleration vector, always points radially inward. Roll this sheet of paper into a cylinder. Now the (Euclidean) derivative of your velocity has a component that sometimes points inward toward the axis of the cylinder depending on whether you're near a solstice or an equinox. (At the point of the circle when you are moving parallel to the axis, there is no inward acceleration. At the point, the velocity is along the cylinder's bend, the inward acceleration is maximum.) This is the (Euclidean) normal component. The covariant derivative component is the component parallel to the cylinder's surface, and is the same as that before you rolled the sheet into a cylinder.
A covariant derivative is a (Koszul) connection on the tangent bundle and other tensor bundles. Thus it has a certain behavior on vector fields that extends that of the usual differential on functions. It also extends in a unique way to the duals of vector fields (i.e., covector fields), and to arbitrary tensor fields, that ensures compatibility with the tensor product and trace operations (tensor contraction).
Given a point p of the manifold, a real function f on the manifold, and a tangent vector v at p, the covariant derivative of f at p along v is the scalar at p, denoted , that represents the principal part of the change in the value of f when the argument of f is changed by the infinitesimal displacement vector v. (This is the differential of f evaluated against the vector v.) Formally, there is a differentiable curve such that and , and the covariant derivative of f at p is defined by
When v is a vector field, the covariant derivative is the function that associates with each point p in the common domain of f and v the scalar . This coincides with the usual Lie derivative of f along the vector field v.
A covariant derivative at a point p in a smooth manifold assigns a tangent vector to each pair , consisting of a tangent vector v at p and vector field u defined in a neighborhood of p, such that the following properties hold (for any vectors v, x and y at p, vector fields u and w defined in a neighborhood of p, scalar values g and h at p, and scalar function f defined in a neighborhood of p):
- is linear in so
- is additive in so:
- obeys the product rule; i.e., where is defined above,
If u and v are both vector fields defined over a common domain, then denotes the vector field whose value at each point p of the domain is the tangent vector . Note that depends not only on the value of v at p but also on values of u in an infinitesimal neighbourhood of p because of the last property, the product rule.
Given a field of covectors (or one-form) defined in a neighborhood of p, its covariant derivative is defined in a way to make the resulting operation compatible with tensor contraction and the product rule. That is, is defined as the unique one-form at p such that the following identity is satisfied for all vector fields u in a neighborhood of p
The covariant derivative of a covector field along a vector field v is again a covector field.
Once the covariant derivative is defined for fields of vectors and covectors it can be defined for arbitrary tensor fields by imposing the following identities for every pair of tensor fields and in a neighborhood of the point p:
and for and of the same valence
The covariant derivative of a tensor field along a vector field v is again a tensor field of the same type.
Explicitly, let T be a tensor field of type (p, q). Consider T to be a differentiable multilinear map of smooth sections α1, α2, ..., αq of the cotangent bundle T∗M and of sections X1, X2, ... Xp of the tangent bundle TM, written T(α1, α2, ..., X1, X2, ...) into R. The covariant derivative of T along Y is given by the formula
Given coordinate functions
any tangent vector can be described by its components in the basis
The covariant derivative of a basis vector along a basis vector is again a vector and so can be expressed as a linear combination . To specify the covariant derivative it is enough to specify the covariant derivative of each basis vector field along .
the coefficients are called Christoffel symbols of the second kind.
Then using the rules in the definition, we find that for general vector fields and we get
The first term in this formula is responsible for "twisting" the coordinate system with respect to the covariant derivative and the second for changes of components of the vector field u. In particular
In words: the covariant derivative is the usual derivative along the coordinates with correction terms which tell how the coordinates change.
For covectors similarly we have
The covariant derivative of a type (r, s) tensor field along is given by the expression:
Or, in words: take the partial derivative of the tensor and add: for every upper index , and for every lower index .
If instead of a tensor, one is trying to differentiate a tensor density (of weight +1), then you also add a term
If it is a tensor density of weight W, then multiply that term by W. For example, is a scalar density (of weight +1), so we get:
where semicolon ";" indicates covariant differentiation and comma "," indicates partial differentiation. Incidentally, this particular expression is equal to zero, because the covariant derivative of a function solely of the metric is always zero.
For a scalar field , covariant differentiation is simply partial differentiation:
For a contravariant vector field , we have:
For a covariant vector field , we have:
For a type (2,0) tensor field , we have:
For a type (0,2) tensor field , we have:
For a type (1,1) tensor field , we have:
The notation above is meant in the sense
Covariant derivatives do not commute; i.e. . It can be shown that:
where is the Riemann tensor. Similarly,
The latter can be shown by taking (without loss of generality) that .
In textbooks on physics, the covariant derivative is sometimes simply stated in terms of its components in this equation.
Once again this shows that the covariant derivative of a vector field is not just simply obtained by differentiating to the coordinates , but also depends on the vector v itself through .
In some older texts (notably Adler, Bazin & Schiffer, Introduction to General Relativity), the covariant derivative is denoted by a double pipe:
Derivative along curveEdit
Since the covariant derivative of a tensor field at a point depends only on the value of the vector field at one can define the covariant derivative along a smooth curve in a manifold:
Note that the tensor field only needs to be defined on the curve for this definition to make sense.
In particular, is a vector field along the curve itself. If vanishes then the curve is called a geodesic of the covariant derivative. If the covariant derivative is the Levi-Civita connection of a certain metric then the geodesics for the connection are precisely the geodesics of the metric that are parametrised by arc length.
The derivative along a curve is also used to define the parallel transport along the curve.
Sometimes the covariant derivative along a curve is called absolute or intrinsic derivative.
Relation to Lie derivativeEdit
A covariant derivative introduces an extra geometric structure on a manifold that allows vectors in neighboring tangent spaces to be compared. This extra structure is necessary because there is no canonical way to compare vectors from different vector spaces, as is necessary for this generalization of the directional derivative. There is however another generalization of directional derivatives which is canonical: the Lie derivative. The Lie derivative evaluates the change of one vector field along the flow of another vector field. Thus, one must know both vector fields in an open neighborhood. The covariant derivative on the other hand introduces its own change for vectors in a given direction, and it only depends on the vector direction at a single point, rather than a vector field in an open neighborhood of a point. In other words, the covariant derivative is linear (over C∞(M)) in the direction argument, while the Lie derivative is linear in neither argument.
Note that the antisymmetrized covariant derivative ∇uv − ∇vu, and the Lie derivative Luv differ by the torsion of the connection, so that if a connection is torsion free, then its antisymmetrization is the Lie derivative.
- Affine connection
- Christoffel symbols
- Connection (algebraic framework)
- Connection (mathematics)
- Connection (vector bundle)
- Connection form
- Exterior covariant derivative
- Gauge covariant derivative
- Introduction to mathematics of general relativity
- Levi-Civita connection
- Parallel transport
- Ricci calculus
- Tensor derivative (continuum mechanics)
- List of formulas in Riemannian geometry
- Einstein, Albert (1922). "The General Theory of Relativity". The Meaning of Relativity.
- Ricci, G.; Levi-Civita, T. (1901). "Méthodes de calcul différential absolu et leurs applications". Mathematische Annalen. 54: 125–201. doi:10.1007/bf01454201.
- Riemann, G. F. B. (1866). "Über die Hypothesen, welche der Geometrie zu Grunde liegen". Gesammelte Mathematische Werke.; reprint, ed. Weber, H. (1953), New York: Dover.
- Christoffel, E. B. (1869). "Über die Transformation der homogenen Differentialausdrücke zweiten Grades". Journal für die reine und angewandte Mathematik. 70: 46–70.
- cf. with Cartan, É (1923). "Sur les variétés à connexion affine et la theorie de la relativité généralisée". Annales, École Normale. 40: 325–412.
- Koszul, J. L. (1950). "Homologie et cohomologie des algebres de Lie". Bulletin de la Société Mathématique. 78: 65–127.
- The covariant derivative is also denoted variously by vu, Dvu, or other notations.
- In many applications, it may be better not to think of t as corresponding to time, at least for applications in general relativity. It is simply regarded as an abstract parameter varying smoothly and monotonically along the path.
- Kobayashi, Shoshichi; Nomizu, Katsumi (1996). Foundations of Differential Geometry, Vol. 1 (New ed.). Wiley Interscience. ISBN 0-471-15733-3.
- I.Kh. Sabitov (2001) , "Covariant differentiation", in Hazewinkel, Michiel, Encyclopedia of Mathematics, Springer Science+Business Media B.V. / Kluwer Academic Publishers, ISBN 978-1-55608-010-4
- Sternberg, Shlomo (1964). Lectures on Differential Geometry. Prentice-Hall.
- Spivak, Michael (1999). A Comprehensive Introduction to Differential Geometry (Volume Two). Publish or Perish, Inc. | <urn:uuid:cab70e82-fcaf-4ae6-ae38-3e9cffc37411> | 3 | 4,555 | Knowledge Article | Science & Tech. | 36.727827 | 95,579,822 |
We conducted a model experiment to examine the hypothesis that the spatial and temporal specificity of spawning of walleye pollock (Theragra chalcogramma) in Shelikof Strait, Alaska, evolved to optimize physical transport to the juvenile nursery area near the Shumagin Islands some 375 km to the southwest. The alternative hypothesis is that factors other than physical transport alone must also be important in the choice of spawning location and timing. We used a coupled biophysical model consisting of a three-dimensional hydrodynamic model of the currents in the region, an individual-based model of the early life stages of pollock, and a nutrient-phytoplankton-zooplankton model that provides a spatially and temporally dynamic source of food for larval pollock. Results showed that fish spawned to the south of Kodiak Island, or too early (February) or too late (July), did not reach the Shumagin Island nursery area by early September. However, the potential region and time of spawning that did allow successful transport to the nursery area was much broader than the observed spawning region and time. Therefore, factors other than physical transport alone must be considered in explaining the specificity of the location and timing of spawning for this stock.
Mendeley saves you time finding and organizing research
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From Event: SPIE Optical Engineering + Applications, 2017
Future astronomical telescopes in space will have architectures with complex and demanding requirements in order to meet their science goals. The missions currently being studied by NASA for consideration in the next Decadal Survey range in wavelength from the X-ray to Far infrared; examining phenomenon from imaging exoplanets and characterizing their atmospheres to detecting gravitational waves. These missions have technical challenges that are near or beyond the state of the art from the telescope to the detectors. This paper describes some of these challenges and possible solutions. Promising measurements and future demonstrations are discussed that can enhance or enable these missions.
Arnold A. Barnes, J. Scott Knight, Paul A. Lightsey, Alex Harwit, and Laura Coyle, "Technology advancements for future astronomical missions," Proc. SPIE 10398, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VIII, 103980K (Presented at SPIE Optical Engineering + Applications: August 07, 2017; Published: 5 September 2017); https://doi.org/10.1117/12.2274833.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations. | <urn:uuid:c9ad70d6-4b62-4649-ac46-40858269eadd> | 2.953125 | 307 | Truncated | Science & Tech. | 25.506269 | 95,579,826 |
The amount of plastic in the ocean is set to treble in a decade unless litter is curbed, a major report has warned.
Plastics is just one issue facing the world’s seas, along with rising sea levels, warming oceans, and pollution, it says.
But the Foresight Future of the Sea Report for the UK government said there are also opportunities to cash in on the “ocean economy”.
They say this is predicted to double to $ 3 trillion (£2 trillion) by 2030.
The report says much more knowledge is needed about the ocean. The authors say the world needs a Mission to “Planet Ocean” to mirror the excitement of voyaging to the moon and Mars.
The Foresight reports are written by experts to brief ministers on medium and long-term issues of significance. This one has been signed off by ministers from four different departments as the authors emphasise the need for a joined-up oceans policy.
One of the authors, Prof Edward Hill from the UK National Oceanography Centre told BBC News: “The ocean is critical to our economic future. Nine billion people will be looking to the ocean for more food. Yet we know so little of what’s down there.
“We invest a lot of money and enthusiasm for missions to space – but there’s nothing living out there. The sea bed is teeming with life. We really need a mission to planet ocean – it’s the last frontier.”
Another of the authors, the chief scientist for the UK government’s environment department Ian Boyd, agreed: “The ocean is out of sight, out of mind,” he said.
He told BBC News: “There’s a continuous process of exploring for new things to exploit in the oceans, and that’s happening faster than we scientists can keep up with. My suspicion is legislation is also struggling to keep up – and obviously there are risks in that.”
He said offshore wind farms, oil industries and mining firms were spreading into unexplored areas. “Scientists need to get in there faster than the commercial people or at least at the same time – to put proper regulation in place to govern those industries.”
The report highlights many concerns, including the current worry about ocean plastic litter, which it forecasts will treble between 2015 and 2025.
But it stresses that the ocean is being assailed from many different types of pollution – including run-off pesticides and fertilisers from farms, industrial toxins like PCBs, and pharmaceuticals.
The authors say if governments can identify ways of protecting biodiversity in the seas, there are riches to be harvested – including nodules of metals and possibly even cures for cancer.
They predict that the biggest industrial growth in the seas will come from offshore wind, followed by marine aquaculture and fish processing. The report also projects an increase in industrial capture of wild fish.
This latter suggestion alarmed Rachel Jones, a marine expert from London Zoo, ZSL. She told BBC News: “Given that 90% of global fisheries are either at or in excess of sustainable catch levels, I can’t really see how they are going to expand capture fisheries.”
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Mammoth Steppe Ecosystem Restoration To Prevent Permafrost Carbon Emissions.This entry was posted
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Melting Arctic Permafrost represents fundamental threat to global climate. Restoring “Mammoth Steppe” could help.
Arctic permafrost contains ~1600 gigatons of carbon, approximately twice as much as the earths atmosphere (Tarnocai et al 2009). Due to accelerated warming at high latitudes this permafrost is beginning to melt. This will release large amounts of carbon into the atmosphere and create a positive feedback loop. Although many scientists are continuing to research the role permafrost carbon will play in global climate, Russian scientist Sergey Zimov, the discoverer of this “carbon bomb” (Zimov et all 1997) has an unusual, and rather poetic, plan to mitigate this effect. He believes that by restoring the “Mammoth Steppe” ecosystem, a grassland that once stretched from Spain to Canada and harbored tremendous herds of roaming ungulates – like the Serengeti but woollier – he can prevent permafrost from thawing. Not waiting for the rest of the world to take action, he has started, in the most remote corner of north east Siberia, a project he calls Pleistocene Park which will be a proof of concept for his vision.
What actions do you propose?
Introducing large numbers of herbivores to the arctic will stimulate an ecological transformation from the current tundra and taiga ecosystems back to the “Mammoth Steppe” — a grassland ecosystem maintained by large numbers of herbivores that existed up until the end of the last ice age. Recent research (Zimov 2012) has shown that even during the last glacial maximum this ecosystem was able to maintain herbivore densities to the order of 11 tons per square kilometer. In Pleistocene Park animals introduced so far include Yakutian horses, muskoxen, European bison, reindeer, elk, and moose. Additional candidate species include Canadian wood bison, American plains bison, yak, Prezivalski’s horse, Bactrian camel, sagia antelope, Yakutian goats, and llamas. This ecosystem can be created and maintained by cold adapted animals that currently live on the earth. Cloning a wooly mammoth is not necessary for the success of this project. However, when a ecologically meaningful population of mammoths derived from currently underway mammoth cloning projects are available they will also be included.
During the ice age the Mammoth Steppe was able to support such high herbivore densities because these animals, via physical disturbance and rapid nutrient cycling, maintained a grassland ecosystem that operated near it’s photosynthetic maximum capacity. This ecosystem was so productive in fact that it pulled large quantities of Co2 from the earth’s atmosphere and added it to the soil where it froze. Year by year, over tens of thousands of years, this soil built up to create the permafrost carbon deposits we find in the arctic today.
Restoring this ecosystem will effect global climate in three ways: 1) A meter of winter snow is a very effective thermo insulator. The ground absorbs heat during the summer but due to the layer of snow is unable to radiate this heat back into the atmosphere during the long and very cold arctic winter. This leads to a net increase in soil temperature. Millions of herbivores will spend the winter with one thought on their minds: finding enough food to not starve to death. In their search they will dig through or trample every inch of arctic snow looking for every last blade of grass. This will radically decrease the insulitave effect of the snow and cause a net temperature drop in the soil – preventing it from thawing even in a warmer climate. Early experimental results have show a net 4 degrees C drop in soil temperature in locations where herbivores are present (Sergey Zimov, personal communication). If permafrost stays frozen all that carbon stays where it is rather then releasing into the atmosphere. 2) A grassland ecosystem will have much higher albedo then the current tundra and taiga ecosystems. The scope of this effect is currently impossible to quantify but it could in theory be quite large. 3) In the very long term (thousands of years) this high productivity ecosystem will began drawing carbon out of the atmosphere and once again sequester it in frozen arctic soils.
Who will take these actions?
Initial proof of concept will be demonstrated by Sergey Zimov and his son Nikita Zimov at their research site Pleistocene Park. They will need funding from external partners to expand their project from it’s current status. Full implementation will be carried out by the governments of Russia, The United States, and Canada as well as international organizations.
Where will these actions be taken?
Project locations are Russia, Alaska, and Canada. Although permafrost covers approximately 25% of the northern hemisphere land mass the largest concentrations of carbon are in a few relatively small locations in north east Siberia, central Alaska, and the Yukon Territory of Canada. Pleistocene Park, Sergey Zimov’s experimental pilot project is located near the town of Cherski in the republic of Yakutia in the Russian Federation.
How much will emissions be reduced or sequestered vs. business as usual levels?
Projected emissions from thawing permafrost are not currently included in climate models and great uncertainty exists on the scale and time frame of these emissions. Sergey Zimov estimates that within 20 years methane and Co2 emissions from one relatively small region of Siberia will equal ~2 gigatons carbon per year (7.32 gigatones Co2) or ~20% of total anthropogenic emissions. Due to anaerobic decomposition some portion of this permafrost carbon will be converted to methane rather then Co2. Predicting the ratio of Co2 to Methane emitted from thawing permafrost is currently very difficult.
Because of the time frames necessary to implement Zimov’s plan at a meaningful scale, even if initiated very soon, significant emissions of permafrost carbon are inevitable. However, by the second half of this century a restored mammoth steppe ecosystem could be preventing the emission of ~6 gigatons of Co2 per year, possibly a lot more.
What are other key benefits?
In addition to preventing large Co2 and methane emissions this project will significantly increase arctic albedo and over the long term began drawing carbon out of the atmosphere and sequestering it in the ground.
At the end of the last ice age human hunters pushing into the arctic overhunted the large herbivores that maintained the grassland ecosystem. Because it appears probable that the collapse of the Mammoth Steppe ecosystem was due not to climate change but to human hunting, restoring this ecosystem to it’s former function would correct the largest human caused environmental tragedy prior to the modern era.
On a pragmatic note this ecosystem could provide a large amount of high quality protean for human consumption.
What are the proposal’s costs?
Because northeastern Siberia has such a low human population density direct negative economic consequences would be quite low, especially when compared with the direct economic benefits to local residents (meat production, tourism). It is important to note that project calls ecosystem conversion from the current tundra and taiga to Mammoth Steppe grassland on a massive geographic scale. It is possible that there will be unintended consequences.
The short term will be dedicated to experimenting, data gathering, and expanding Pleistocene Park — the proof of concept. This period is also seeing the establishment of seed populations of herbivores in places other then Pleistocene Park, for example the 2015 reintroduction of Canadian Wood Bison to the Yukon river delta in Alaska and the 2006 (re?)introduction to Yakutia in Siberia.
The medium term will see large scale implementation by the governments of Russia, America, and Canada working with international organizations like the UN.
Because wild ecosystems are self sustaining the primary long-term action will be managing human impacts on the ecosystem – for example enforcing anti-poaching regulations and managing hunting for sustainability.
read more original article https://climatecolab.org
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Authors: Sjaak Uitterdijk
Otto Stern and Walter Gerlach demonstrated in 1922 experimentally the “existence of space quantization in a magnetic field”, using their own words. The result of this experiment is later on used to introduce the so-called intrinsic spin angular momentum of elementary and other particles. This article describes what went wrong in the applied argumentation. In 1896 Zeeman and Lorentz showed experimentally and theoretically that atoms emit ‘shifted’ frequencies when exposed to an external magnetic field. This phenomenon has been used to demonstrate the existence of spinning electrons. However, it is shown that this demonstration is not convincing at all.
Comments: 10 Pages. Version 1 presents the wrong expression ‘angular moment’ in stead of ‘angular momentum’, now used in version 2.
Unique-IP document downloads: 99 times
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This section is all about creating scroll bar in Java SWT
The given example will show you how to create scroll bar in Java using SWT, for that we have created a class with the name ScrollBarExamle that imports a package org.eclipse.swt.widgets, which is used to create ScrollBar in Java. Further in this example, we have create a list by using the class List. A string is added to the list by using the method list.add(). We have create a for loop to print the specified string 20 times.
The styles SWT.V_SCROLL, SWT.H_SCROLL provided by the class ScrollBar creates the vertical and horizontal bars.
Here is the code of ScrollBarExample.java
Output will be displayed as: | <urn:uuid:24a64f9e-fe01-471c-a82e-ba9fb4ec3283> | 3.375 | 166 | Tutorial | Software Dev. | 74.469932 | 95,579,887 |
They have observed precisely what happens using a super-fast camera and have made a computer simulation of the process. This shows how the jet is forced upwards, layer by layer, by the surrounding water pressure. The simulation corresponds very closely with observations.
They have also formulated a theoretical model based on this that explains the extremely high speed of the water jet. The researchers are publishing their findings in the renowned journal, Physical Review Letters. These results are not only of academic significance as jets on the impact of an object on a liquid are frequent occurrences in nature and industry.
If one drops a stone into a pond, a very rapid, thin jet of water spouts upwards. This is an everyday phenomenon that occurs frequently in nature and industry. However, the rich and complex dynamics underlying such a system are only revealed if viewed using a high-speed camera. The latter shows how the downward movement of the object is converted into the upward movement of the jet.
A cavity forms behind the object during impact on the water surface. This cavity is subsequently compressed by hydrostatic pressure, which leads to the formation of the jet. In their experiments, FOM PhD candidate Stephan Gekle, José Manuel Gordillo of the University of Seville and Devaraj van der Meer and Detlef Lohse of the University of Twente demonstrate how the wall of the cavity forces the jet upward as it implodes, just like toothpaste being squeezed out of a tube, but many times faster, of course. Incidentally, a jet which is forced downward, deeper into the liquid, is also created at the same time. This second jet is not visible on the surface.
In order to examine the dynamics of the impact in a highly controlled manner, the researchers draw a circular disc through the water surface using a linear motor with a constant speed. Subsequently a high-speed camera is used to take images with a speed of up to 30,000 frames per second.
The formation and constriction of the cavity and the formation of the jet can thus be followed in detail. A computer simulation of the process – which corresponds very closely to the experiment – enables the researchers to study the resulting flow profile. It appears that the jet is forced upward, layer by layer, by the imploding wall. The researchers have formulated a theoretical model to explain the enormous speed of the water jet on the basis of this observation.
Wiebe van der Veen | alfa
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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posted by Zachary
In the "Methode Champenoise," grape juice is fermented in a wine bottle to produce sparkling wine. The reaction is given below. C6H12O6(aq) 2 C2H5OH(aq) + 2 CO2(g) Fermentation of 712 mL grape juice (density = 1.0 g/cm3) is allowed to take place in a bottle with a total volume of 825 mL until 12% by volume of the liquid is ethanol (C2H5OH). Assuming that the CO2 is insoluble in H2O (actually, a wrong assumption), what would be the pressure of CO2 inside the wine bottle at 30.°C? (The density of ethanol is 0.79 g/cm3.)
You need to find the arrow button and use it with equations. --> or ==> or >>>.
I think the first thing to do is to convert 12% v/v to grams ethanol. That is 12 mL ethanol/100 mL soln. Scale that up to 712 (I guess we assume ALL of the grape juice is glucose which of course is not quite right so we lump that in with the error made in assuming CO2 is not soluble in water).
12 mL ethanol x 712/100 = 85.4 mL ethanol. Convert that to grams using density. mass = volume x density alcohol which is given at the end of the problem.
mols ethanol = grams/molar mass
Use the coefficients in the balanced equation to convert mols ethanol to mols CO2.
Then use PV = nRT to solve for P CO2 at the conditions listed. Post your work if you get stuck.
I found the moles of CO2 and I got 1.47. 85.4 L ethanol * .79 g/cm3 = 67.5g ethanol. 67.5/(12+12+5+16+1)= 1.47 moles ethanol. 1.47 moles C2H5OH *(2 moles C2H5OH/ 2 moles CO2) = 1.47 moles CO2. What do I use for the volume? do I use the volume of the bottle, the volume of the bottle minus the volume of the ethanol, or the volume occupied by the grape juice?
Sorry, I made a mistake. 85.4 mL = .0854 L. .0854 L * .79 g/cm3 = .0675g. .0675/46(MM of C2H5OH) = .0147 moles ethanol. .0147 moles ethanol = .0147 moles CO2.
I'm still not sure which volume to use though. would it be 825 mL, 825mL - 85.4 mL, or 712 mL? | <urn:uuid:8daf8784-1751-4660-ae49-b999431ace01> | 3.09375 | 587 | Q&A Forum | Science & Tech. | 96.915173 | 95,579,907 |
Registered: 1352930725 Posts: 111
Reply with quote #1
Sunlight can be used to generate electricity using solar panels but it also can add heat to storage media like water, liquid metals, and molten salts. The problem for scientists is that those phase changes occur quite rapidly. If there were a way to slow them down and control how and when the transitions take place more precisely, a new heat storage battery could result. Researchers at MIT think they have discovered a way to do exactly that. Writing in the journal Nature Communications, they say they have come up with a way to embed “molecular switches” into the phase change materials that absorb heat. Those switches can be operated by pulses of light to control when and how fast phase changes occur. They say it is possible to allow the release of heat to continue even past the temperature where a change in phase normally occurs. “The trouble with thermal energy is, it’s hard to hold onto it,” says Jeffrey Grossman, one of the authors of the report. The researchers use “little molecules that undergo a structural change when light shines on them.” The result is phase change materials that release heat on demand. The ramifications are enormous. “There are so many applications where it would be useful to store thermal energy in a way that lets you trigger it when needed,” he says. “By integrating a light-activated molecule into the traditional picture of latent heat, we add a new kind of control knob for properties such as melting, solidification, and supercooling.” https://cleantechnica.com/2017/11/21/mit-researchers-develop-new-heat-storage-battery-laboratory/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+IM-cleantechnica+%28CleanTechnica%29 __________________ Go Solar!
Registered: 1388591029 Posts: 2,748
Reply with quote #2
Hmmm interesting. It might be a way to store waste heat from other systems, too.
__________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay | <urn:uuid:ce3c3e44-271e-4b6b-9d78-753474924316> | 3.3125 | 470 | Comment Section | Science & Tech. | 49.928078 | 95,579,954 |
One of the first things we learn in chemistry class is that solids conduct heat better than liquids. But a new study suggests that in nanoscale materials, this is not necessarily the case.
Using computer simulations, researchers at Rensselaer Polytechnic Institute have found that heat may actually move better across interfaces between liquids than it does between solids. The findings, which were published online Oct. 11 in the journal Nano Letters, provide insights that could prove useful in fields ranging from computer chip manufacturing to cancer treatment.
Conduction is the movement of heat from a warmer substance to a cooler substance, as when a spoon heats up after sitting in a cup of hot soup. "Liquids generally have low thermal conductivity when compared to solids," says Pawel Keblinski, associate professor of materials science and engineering at Rensselaer and coauthor of the paper. "For example, diamond is one of the best conductors around, with a conductivity of about 5,000 times that of water." Metals also tend to be good conductors, which is why the same spoon would normally feel cold to the touch -- it conducts heat away from the hand.
Jason Gorss | EurekAlert!
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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Some calculations on radioactive fallout with especial reference to the secular variations in potential gradient at Eskdalemuir, Scotland
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From a study of the variations in potential gradient at Eskdalemuir, Scotland, it is shown that the radioactivity there has roughly doubled during the past six years; in other words, a radioactive contamination equal in activity to the natural background has occurred. Calculations indicate that only some 2% of this contamination can be ascribed to world-wide fall-out following thermonuclear explosions; the remainder must have been generated locally. The obvious sources are the atomic stations — notably Windscale — in Cumberland, and it is considered that, apart from the accident in October 1957, Windscale has leaked radioactive material ever since it first came into operation. The resultant contamination is very considerable and its relation to danger levels is discussed.
KeywordsAtomic Station Potential Gradient Secular Variation Natural Background Radioactive Material
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- Gorham, Eville, 1958: Nature (London), 181, 1523.Google Scholar
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- Stewart N. G., 1958: Smokeless Air, 28, 285.Google Scholar | <urn:uuid:d832afb2-92e6-4a5b-8cd3-1e6cdd1b33a9> | 2.65625 | 346 | Truncated | Science & Tech. | 40.978968 | 95,580,006 |
Wisconsin Water Science Center
This list of Wisconsin Water Science Center publications spans from 1953 to present. It includes both official USGS publications and journal articles authored by our scientists.
Methods for exploring uncertainty in groundwater management predictions
Models of groundwater systems help to integrate knowledge about the natural and human system covering different spatial and temporal scales, often from multiple disciplines, in order to address a range of issues of concern to various stakeholders. A model is simply a tool to express what we think we know. Uncertainty, due to lack of knowledge or...Jakeman, Anthony J.; Barreteau, Olivier; Hunt, Randall J.; Rinaudo, Jean-Daniel; Ross, Andrew; Guillaume, Joseph H. A.; Hunt, Randall J.; Comunian, Alessandro; Fu, Baihua; Blakers, Rachel S
StreamThermal: A software package for calculating thermal metrics from stream temperature data
Improving quality and better availability of continuous stream temperature data allows natural resource managers, particularly in fisheries, to understand associations between different characteristics of stream thermal regimes and stream fishes. However, there is no convenient tool to efficiently characterize multiple metrics reflecting stream...Tsang, Yin-Phan; Infante, Dana M.; Stewart, Jana S.; Wang, Lizhu; Tingly, Ralph; Thornbrugh, Darren; Cooper, Arthur; Wesley, Daniel
Simulation of climate change effects on streamflow, groundwater, and stream temperature using GSFLOW and SNTEMP in the Black Earth Creek Watershed, Wisconsin
A groundwater/surface-water model was constructed and calibrated for the Black Earth Creek watershed in south-central Wisconsin. The model was then run to simulate scenarios representing common societal concerns in the basin, focusing on maintaining a cold-water resource in an urbanizing fringe near its upper stream reaches and minimizing...Hunt, Randall J.; Westenbroek, Stephen M.; Walker, John F.; Selbig, William R.; Regan, R. Steven; Leaf, Andrew T.; Saad, David A.
Evaluation of leaf removal as a means to reduce nutrient concentrations and loads in urban stormwater
While the sources of nutrients to urban stormwater are many, the primary contributor is often organic detritus, especially in areas with dense overhead tree canopy. One way to remove organic detritus before it becomes entrained in runoff is to implement a city-wide leaf collection and street cleaning program. Improving our knowledge of the...Selbig, William R.
Comparison of benthos and plankton for selected areas of concern and non-areas of concern in western Lake Michigan Rivers and Harbors in 2012
Recent data are lacking to assess whether impairments still exist at four of Wisconsin’s largest Lake Michigan harbors that were designated as Areas of Concern (AOCs) in the late 1980s due to sediment contamination and multiple Beneficial Use Impairments (BUIs), such as those affecting benthos (macroinvertebrates) and plankton (zooplankton and...Eikenberry, Barbara C. Scudder; Bell, Amanda H.; Olds, Hayley T.; Burns, Daniel J.
Understanding the hydrologic impacts of wastewater treatment plant discharge to shallow groundwater: Before and after plant shutdown
Effluent-impacted surface water has the potential to transport not only water, but wastewater-derived contaminants to shallow groundwater systems. To better understand the effects of effluent discharge on in-stream and near-stream hydrologic conditions in wastewater-impacted systems, water-level changes were monitored in hyporheic-zone and shallow...Hubbard, Laura E.; Keefe, Steffanie H.; Kolpin, Dana W.; Barber, Larry B.; Duris, Joseph W.; Hutchinson, Kasey J.; Bradley, Paul M.
Nutrient delivery to Lake Winnipeg from the Red-Assiniboine River Basin – A binational application of the SPARROW model
Excessive phosphorus (TP) and nitrogen (TN) inputs from the Red–Assiniboine River Basin (RARB) have been linked to eutrophication of Lake Winnipeg; therefore, it is important for the management of water resources to understand where and from what sources these nutrients originate. The RARB straddles the Canada–United States border and...Benoy, Glenn A.; Jenkinson, R. Wayne; Robertson, Dale M.; Saad, David A.
Regional effects of agricultural conservation practices on nutrient transport in the Upper Mississippi River Basin
Despite progress in the implementation of conservation practices, related improvements in water quality have been challenging to measure in larger river systems. In this paper we quantify these downstream effects by applying the empirical U.S. Geological Survey water-quality model SPARROW to investigate whether spatial differences in conservation...Garcia, Ana Maria.; Alexander, Richard B.; Arnold, Jeffrey G.; Norfleet, Lee; White, Michael J.; Robertson, Dale M.; Schwarz, Gregory E.
Simulated impacts of climate change on phosphorus loading to Lake Michigan
Phosphorus (P) loading to the Great Lakes has caused various types of eutrophication problems. Future climatic changes may modify this loading because climatic models project changes in future meteorological conditions, especially for the key hydrologic driver — precipitation. Therefore, the goal of this study is to project how P loading may...Robertson, Dale M.; Saad, David A.; Christiansen, Daniel E.; Lorenz, David J
Quantification of human-associated fecal indicators reveal sewage from urban watersheds as a source of pollution to Lake Michigan
Sewage contamination of urban waterways from sewer overflows and failing infrastructure is a major environmental and public health concern. Fecal coliforms (FC) are commonly employed as fecal indicator bacteria, but do not distinguish between human and non-human sources of fecal contamination. Human Bacteroides and humanLachnospiraceae,...Olds, Hayley T.; Dila, Deborah K.; Bootsma, Melinda J.; Corsi, Steven; McLellan, Sandra L.
Benthos and plankton community data for selected rivers and harbors along the western Lake Michigan shoreline, 2014
Benthos (benthic invertebrates) and plankton (zooplankton and phytoplankton) communities were sampled in 2014 at 10 Wisconsin rivers and harbors, including 4 sites in Great Lakes Areas of Concern and 6 less degraded comparison sites with similar physical and chemical characteristics, including climate, latitude, geology, and land use. Previous U.S...Scudder Eikenberry, Barbara C.; Burns, Daniel J.; Olds, Hayley T.; Bell, Amanda H.; Mapel, Kassidy T.
Long-term trends in a Dimictic Lake
The one-dimensional hydrodynamic ice model, DYRESM-WQ-I, was modified to simulate ice cover and thermal structure of dimictic Lake Mendota, Wisconsin, USA, over a continuous 104-year period (1911–2014). The model results were then used to examine the drivers of changes in ice cover and water temperature, focusing on the responses to...Robertson, Dale M.; Hsieh, Yi-Fang; Lathrop, Richard C; Wu, Chin H; Magee, Madeline; Hamilton, David P. | <urn:uuid:9363aebf-0c65-49df-957c-22da1dd85d17> | 2.609375 | 1,525 | Content Listing | Science & Tech. | 34.270332 | 95,580,013 |
Section: Perl Programmers Reference Guide (1)
Return to Main Contents
config_data - Query or change configuration of Perl modules
# Get config/feature values
config_data --module Foo::Bar --feature bazzable
config_data --module Foo::Bar --config magic_number
# Set config/feature values
config_data --module Foo::Bar --set_feature bazzable=1
config_data --module Foo::Bar --set_config magic_number=42
# Print a usage message
The config_data tool provides a command-line interface to the
configuration of Perl modules. By configuration, we mean something
akin to user preferences or local settings. This is a
formalization and abstraction of the systems that people like Andreas
Koenig (CPAN::Config), Jon Swartz (HTML::Mason::Config), Andy
Wardley (Template::Config), and Larry Wall (perl's own Config.pm)
have developed independently.
The configuration system emplyed here was developed in the context of
Module::Build. Under this system, configuration information for a
module Foo, for example, is stored in a module called
Foo::ConfigData) (I would have called it Foo::Config, but that
was taken by all those other systems mentioned in the previous
paragraph...). These ...::ConfigData modules contain the
configuration data, as well as publically accessible methods for
querying and setting (yes, actually re-writing) the configuration
data. The config_data script (whose docs you are currently
reading) is merely a front-end for those methods. If you wish, you
may create alternate front-ends.
The two types of data that may be stored are called config values
and feature values. A config value may be any perl scalar,
including references to complex data structures. It must, however, be
serializable using Data::Dumper. A feature is a boolean (1 or
This script functions as a basic getter/setter wrapper around the
configuration of a single module. On the command line, specify which
module's configuration you're interested in, and pass options to get
or set config or feature values. The following options are
Specifies the name of the module to configure (required).
When passed the name of a feature, shows its value. The value will
be 1 if the feature is enabled, 0 if the feature is not enabled, or
empty if the feature is unknown. When no feature name is supplied,
the names and values of all known features will be shown.
When passed the name of a config entry, shows its value. The value
will be displayed using Data::Dumper (or similar) as perl code.
When no config name is supplied, the names and values of all known
config entries will be shown.
Sets the given feature to the given boolean value. Specify the value
as either 1 or 0.
Sets the given config entry to the given value.
If the --eval option is used, the values in set_config will be
evaluated as perl code before being stored. This allows moderately
complicated data structures to be stored. For really complicated
structures, you probably shouldn't use this command-line interface,
just use the Perl API instead.
Prints a help message, including a few examples, and exits.
Ken Williams, email@example.com
Copyright (c) 1999, Ken Williams. All rights reserved.
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
- SEE ALSO
This document was created by
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A View from Emerging Technology from the arXiv
Using Sound to Filter Bacterial Spores from Water
Acoustic trapping can remove bacterial spores from water, according to a new set of experiments funded by the U.S. Army.
Measuring the quality of water on an ongoing basis is an important task but not one that is always straightforward. Taking samples for chemical analysis is simple enough and can be relatively easily automated. But determining what kind of bacteria are present is a little more tricky because these need to be filtered and removed from the water before testing. And because filters quickly become clogged and useless, this requires human intervention on a regular basis.
So the U.S. Army is funding a project to determine whether sound can help. The idea is to allow the water to flow through a cavity in which a transducer sets up an acoustic standing wave. Any bacterial spores in the water are then subjected to three forces: buoyancy/gravity, the drag of the fluid as flows along and the acoustic pressure from the standing wave.
Having previously worked out how to balance these forces to trap micro-sized polystyrene beads, a group from Western New England College and a company called Physical Sciences, both in Massachusetts, have now perfected the trick for water-borne spores of bacillus cereus bacteria.
The technique captures some 15 percent of the spores passing through the acoustic trap in water travelling at between 40 and 250 ml per minute (ie very slowly) . The trap then needs to be sealed to stop the fluid flow so that the spores fall under gravity into a collection chamber below. “The acoustocollector is ideally suited for large-volume sampling of water supplies for concentration of spores,” says the team.
The spores can then be analysed using spectroscopy of some sort.
That seems potentially useful. However, the team will need to test the device using water from a realistic source which is bound to contain all kinds of gunk in addition to the spores of interest. Whether the spores can be separated in these circumstances remains to be seen.
The U.S. Army clearly has an interest in being able to monitor its own and other people’s water supplies at low cost and remotely if necessary. And it looks as if acoustic trapping may well have the potential to help them do it.
Ref: arxiv.org/abs/1006.5467: Separation Of Bacterial Spores From Flowing Water In Macro-Scale Cavities By Ultrasonic Standing Waves
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Result by tag 7 results
- Apparent temperature
This online calculator computes apparent temperature, taking into consideration wind speed and relative air humidity. It uses Australian Bureau of Meteorology formula
- Heat Index
This calculator calculates heat index (apparent temperature), which is used by US meteorologists to determine the human-perceived equivalent temperature, as how hot it would feel if the humidity were some other value in the shade.
- Humidification loads
This online calculator answers question "how to choose" humidifier, by calculating humidification requirements given initial and target relative humidity and building parameters
This calculator calculates Humindex, index used by Canadian meteorologists to describe how hot the weather feels to the average person, by combining the effect of heat and humidity.
- Relative humidity to absolute humidity and vise versa calculators
First calculator converts relative humidity to absolute humidity for given temperature and barometric pressure. Second calculator converts absolute humidity to relative humidity for given temperature and barometric pressure
- Saturation vapour pressure
This online calculator computes saturation vapour pressure for given temperature and atmospheric (barometric) pressure
- Wind Chill Index
This online calculator computes Wind Chill Index using Wind Chill Formula from Environment Canada | <urn:uuid:c12368a6-3cd3-4025-93d4-9894b8f4a081> | 3.390625 | 247 | Content Listing | Science & Tech. | -46.643816 | 95,580,091 |
HAMPTON, Va., March 2, 2011 /PRNewswire-USNewswire/ -- After nine years in a clean room, an instrument that studies the Earth's atmosphere and protective ozone layer has been returned to service.
NASA's Stratospheric Aerosol and Gas Experiment III-ISS (SAGE III-ISS) will measure ozone, water vapor and aerosols in the atmosphere when it is attached to the International Space Station (ISS) three years from now.
The instrument is scheduled for launch in 2014 on a SpaceX rocket from NASA's Kennedy Space Center in Florida.
"It will ride in the unpressurized trunk of the rocket, and NASA will use robots to dock the instrument on the ISS - kind of like Transformers," said Michael Cisewski, SAGE III-ISS project manager at NASA Langley Research Center in Hampton, Va. "We're mounting to a piece of the ISS that is going up in the next shuttle launch."
SAGE III-ISS is a nearly exact replica of SAGE III Meteor-3M, sent into orbit in 2001 on a Russian satellite. SAGE III Meteor-3M went out of service five years ago when the satellite's power supply stopped working.
The new instrument was built in anticipation of being attached to the space station in 2005. A change in ISS design, however, put those plans on hold.
The instrument was stored in a Class 100 clean room in a sealed shipping container under a continuous gaseous nitrogen purge. The purge kept clean dry "air" inside the instrument.
"Now, everything is falling into place," said Cisewski.
SAGE III-ISS underwent initial testing at Langley the week of February 14, 2011, in a clean room set up in a bay with an afternoon view of the sun.
The instrument was commanded to point to and lock onto the sun as if it were engaging a sunrise event over the horizon. Once locked on, the instrument's scan mirror scanned the full disk of the sun every two seconds. It also was tested at night using the moon as a radiant source.
"It's a matter of testing SAGE III in all its operational modes, solar and lunar, then making some minor modifications," said Patrick McCormick, SAGE principal investigator partnering with NASA through the Center for Atmospheric Sciences at Hampton University in Hampton, Va.
"The nice thing about SAGE III-ISS," McCormick said, "is that being a replica of a proven instrument, the risk for its refurbishment is exceedingly low. SAGE III is a solid, stable instrument."
Unique aspects of SAGE III-ISS include:
- It will be among the early NASA payloads sent into space on a commercial launch vehicle, the SpaceX F9/Dragon. Started in 2002 by Elon Musk, founder of PayPal and Zip2 Corp., SpaceX has developed two launch vehicles, established a launch manifest and is funded by NASA to demonstrate delivery and return of cargo to the space station.
- SAGE III-ISS will be the first instrument to measure the composition of the middle and lower atmosphere from the space station. "ISS is in the perfect orbit to do these sorts of measurements," said Joseph Zawodny, SAGE III-ISS project scientist.
- SAGE is one of NASA's longest running Earth-observing programs. That's significant because long-term collection of this data is necessary to understand climate change.
Previous SAGE instruments include SAGE, launched in 1979, followed by SAGE II in 1984. SAGE II gathered data for more than 20 years, and the information it collected was part of the effort that led to a global ban on chlorofluorocarbons in 1987.
Chlorofluorocarbons were used in air-conditioning units and aerosol spray propellants that contributed to the Earth's shrinking layer of protective ozone, which has begun to recover after the chlorofluorocarbon ban.
Ball Aerospace & Technologies Corp. built the SAGE III-ISS instrument in Boulder, Colo. The European Space Agency and Thales Alenia Space, headquartered in France, are providing a hexapod to keep the instrument pointing in the right direction as the ISS maneuvers in space.
- Michael Finneran, NASA Langley Research Center
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