fiber, also called the v number, is a useful specification. many fiber parameters can be expressed in terms of v, such as : the number of modes at a given wavelength, mode cut off conditions, and propagation constants. for example, the number of guided modes in a step index multimode fiber is given by v2 / 2, and a step index fiber becomes single - mode for a given wavelength when v < 2. 405. mathematically, v = 2π · na · a / λ where a is the fiber core radius. the outer sheath of fiber cables can be removed using electrical cable stripping tools, and scissors or a razor blade can trim the kevlar strength member. however, the fiber coating must be very carefully removed to avoid damaging the fiber surface flaws and scratches are the cause of most fiber failures. the coating can be removed using our f - str fiber strippers. end surface quality is one of the most important factors affecting fiber connector and splice losses. quality endfaces can be obtained by polishing or by cleaving. polishing is employed in connector terminations when the fiber is secured in a ferrule by epoxy. the following describes the popular connectors and their endface preparation styles. fiber optic connector types sma due to its stainless steel structure and low - precision threaded fiber locking mechanism, this connector is used mainly in applications requiring the coupling of high - power laser beams into large - core multimode fibers. typical applications include laser beam delivery systems in medical, bio - medical, and industrial applications. the typical insertion loss of an sma connector is greater than 1 db. st the st connector is used extensively both in the field and in indoor fiber optic lan applications. its high - precision, ceramic ferrule allows its use with both multimode and single - mode fibers. the bayonet style, keyed coupling mechanism featuring push and turn locking of the connector, prevents over tightening and damaging of the fiber end. the insertion loss of the st connector is less than 0. 5 db, with typical values of 0. 3 db being routinely achieved. drilled - out, metallic st connectors, with insertion losses of > 1 db, are used with newports large - core ( > 140 µm ) fibers. fc the fc has become the connector of choice for single - mode fibers and is mainly used in fiber - optic instruments, sm fiber optic components, and in high - speed fiber optic communication links. this high - precision, ceramic ferrule


fibers. fc the fc has become the connector of choice for single - mode fibers and is mainly used in fiber - optic instruments, sm fiber optic components, and in high - speed fiber optic communication links. this high - precision, ceramic ferrule connector is equipped with an anti - rotation key, reducing fiber endface damage and rotational alignment sensitivity of the fiber. the key is also used for repeatable alignment of fibers in the optimal, minimal - loss position. multimode versions of this connector are also available. the typical insertion loss of the fc connector is around 0. 3 db. drilled - out, metallic fc connectors, having insertion losses of > 1 db, are being used with newports large - core ( > 140 µm ) fibers. sc the sc connector is becoming increasingly popular in single - mode fiber optic telecom and analog catv, field deployed links. the high - precision, ceramic ferrule construction is optimal for aligning single - mode optical fibers. the connectors outer square profile combined with its push - pull coupling mechanism, allow for greater connector packaging density in instruments and patch panels. the keyed outer body prevents rotational sensitivity and fiber endface damage. multimode versions of this connector are also available. the typical insertion loss of the sc connector is around 0. 3 db. connector endface preparation once the optical fiber is terminated with a particular connector, the connector endface preparation will determine what the connector return loss, also known as back reflection, will be. the back reflection is the ratio between the light propagating through the connector in the forward direction and the light reflected back into the light source by the connector surface. minimizing back reflection is of great importance in high - speed and analog fiber optic links, utilizing narrow line width sources such as dfb lasers, which are prone to mode hopping and fluctuations in their output. figure 6connector endfacesfigure 7a typical f - bk3 cleave is clean, flat and perpendicular. flat polish a flat polish of the connector surface will result in a back reflection of about - 16 db ( 4 % ). pc polish the physical contact ( pc ) polish results in a slightly curved connector surface, forcing the fiber ends of mating connector pairs into physical contact with each other. this eliminates the fiber - to - air interface, there by resulting in back reflections of - 30 to - 40 db. the pc polish is the most popular connector endface preparation, used in most applications. spc and upc polish in the super pc


the mode profile of the he11 mode of a step index fiber can be approximated by a gaussian distribution with a 1 / e width w given by : where : d is the core diameter, and v is the v - number. for our f - sv fiber, for which v = 2, the gaussian width is approximately 28 % larger than the core diameter, so the light should be focused to a spot size 1. 28 times the core diameter at the fiber surface. for a gaussian laser beam, the required beam diameter d incident upon focusing lens of focal length f to produce a focused spot of diameter w is d = 4λf / ( πw ). given the laser beam waist and divergence, its easy to determine the distance needed between the focusing lens and the laser to expand the beam to the required diameter. the mode field diameter is now given to provide easier matching of lens to optical fiber for a gaussian beam. a high numerical aperture lens must collimate the diverging output beam of a laser diode. newports f - l series diode laser focusing lenses, are ar - coated for high transmittance at popular laser diode wavelengths and with numerical apertures up to 0. 5 are useful for collimating or focusing. mode scrambling and filtering many multimode fiber experiments are sensitive to the distribution of power among the fibers modes. this is determined by the launching optics, fiber perturbations, and the fibers length. mode scrambling is a technique that distributes the optical power in a fiber among all the guided modes. mode filtering simulates the effects of kilometer lengths of fiber by attenuating higher - order fiber modes. figure 8launching conditions in a multimode optical fiber. one scrambling technique is to splice a length of graded - index fiber between two pieces of step - index fiber this ensures that the downstream fibers core is overfilled regardless of launch conditions. mode filtering can be achieved by wrapping a fiber several times around a finger - sized mandrel ; bending sheds the high - order modes. one way to achieve both scrambling and filtering is to introduce microbending to cause rapid coupling between all fiber modes and attenuation of high - order modes. one approach is to place a stripped section of fiber in a box filled with lead shot. a more precise way is to use newports fm - 1 mode scrambler. this specially designed tool uses a calibrated mechanism to introduce microbending for mode scrambling and filtering. ( a )


of fiber in a box filled with lead shot. a more precise way is to use newports fm - 1 mode scrambler. this specially designed tool uses a calibrated mechanism to introduce microbending for mode scrambling and filtering. ( a ) overfilled ( b ) underfilledfigure 9a schematic of coupling of light into an optical fiberfigure 10mode scrambler for optical fibers. the bends tend to couple out higher - order and radiation modes and to distribute the light into a distribution of modes that will remain stable over long distances. cladding mode removal some light is invariably launched into a fibers cladding. though cladding modes dissipate rapidly with fiber length, they can interfere with measurements. for example, the output of a single - mode fiber will not have a gaussian distribution if light is propagating in the cladding. you can remove cladding modes by stripping a length of fiber coating and immersing the bare fiber in an index matching fluid such as glycerin. common optical parameters the following is a list of common optical parameters associated with fiber optic components. please call or visit newports website for application notes on how to measure these parameters. figure 11 port configuration : number of input ports x number of output ports. e. g. 2 x 2 coupling ratio : the ratio of the power at an output port to the launched power expressed in db. e. g. - 10log ( p2 / p1 ). isolation : the ratio of the power at an output port in the transmitted wavelength band to that in the extinguished wavelength band, expressed in db. directivity : the ratio of the power returned to any other input port to the launched power, expressed in db. e. g. - 10log ( p4 / p1 ). bandwidth : the range of operating wavelengths over which performance parameters are specified. excess loss : the ratio of the total power at all output ports to the launched power, expressed in db. e. g. - 10log [ ( p2 + p3 ) / p1 ]. uniformity : the difference between maximum and minimum insertion losses. extinction ratio : the ratio of the residual power in an extinguished polarization state to the transmitted power, expressed in db. return loss : the ratio of the power returned to the input port to the launched power, expressed in db. e. g. - 10log ( p5 / p1 ). polarization - dependent loss ( pdl ) : the maximum (


return loss : the ratio of the power returned to the input port to the launched power, expressed in db. e. g. - 10log ( p5 / p1 ). polarization - dependent loss ( pdl ) : the maximum ( peak - to - peak ) variation in insertion loss as the input polarization varies, expressed in db. fiber optic communications the theoretical bandwidth of optical fiber transmission in the 1550 nm window alone is on the order of terabits. current fiber optic systems have not even begun to utilize the enormous potential bandwidth that is possible. there are two methods that are employed to achieve an increase in bandwidth. the first is known as time division multiplexing or tdm. multiple channels are transmitted on a single carrier by increasing the modulation rate and allotting a time slot to each channel. however, more sophisticated high - speed electronics, at both the transmitting and receiving ends of the communications link, are required when increasing the bit rate of a system. and as the bit rate increases, inherent modulation limiting characteristics of optical fibers become dominant. chromatic and polarization mode dispersion cause pulse spreading, which affects the signal quality over longer transmission distances. an alternate method for increasing the capacity of fiber optic communications systems is known as wavelength division multiplexing, or wdm. by this method, capacity can be increased by using more than one optical carrier ( wavelength ) on a single fiber. therefore, adding a second transmitter and receiver to an optical fiber can double the bandwidth of that communications system. this method of increasing the capacity of an optical system has appeal for a variety of reasons. if a system were to increase in capacity using tdm alone, the existing transmitter and receiver would be replaced with a faster and more expensive transmitter / receiver pair. using wdm, the existing transmitter and receiver do not need to be replaced. a second transmitter / receiver pair of a different wavelength is simply added. this is done by coupling, or multiplexing the output of the two lasers into a single fiber. at the receiving end, the two wavelengths are then separated, or demultiplexed, and each optical carrier is routed to its own receiver. for transmission systems using a 1310 nm laser, a second laser at 1550 nm is usually added. the reason for choosing these wavelengths is that they lie in the windows or ranges of least attenuation. this allows the signal to travel a longer distance. the itu ( international telecommunication union ) has proposed a set of closely spaced wavelengths in the 1550 nm window. this method of w


that they lie in the windows or ranges of least attenuation. this allows the signal to travel a longer distance. the itu ( international telecommunication union ) has proposed a set of closely spaced wavelengths in the 1550 nm window. this method of wdm is known as dense wavelength division multiplexing, or dwdm. these different wavelengths or channels, are spaced 100 ghz apart, which is approximately 0. 8 nm. this set of channels is commonly known as the itu - t grid, and is specified in frequency. the reason the 1550 nm window was chosen by the itu is twofold : it is in one of the windows that has the smallest amount of attenuation ; and it also lies in the band in which erbium doped optical amplifiers operate. itu - t dwdm grid the following diagram is a conceptual example of a fiber optic network. the all - optical network the all - optical network will be the next evolution in optical communications. current dwdm systems are point - to - point links meaning that the signals have a single distinct starting and ending point. research is being performed to help these networks evolve into fully configurable networks, which are not limited to fixed point - to - point links. transparency in the optical layer opens many possibilities for the future. digital and analog transmission can occur on the same fiber. different bit rates using different protocols will all travel together. current research is being performed on reconfiguring an optical network in real time. wavelength selective switching allows wavelengths to be routed through the network individually. some of the applications of this are for network restoration and redundancy, which may reduce or entirely eliminate the need for an entire back up system to help the network recover from failures such as equipment malfunctions or fiber breaks. a reconfigurable network may offer bandwidth on demand to configure itself to optimize for traffic bottlenecks. the future may also include wavelength translation to convert traffic on one wavelength to another wavelength in the optical domain. all optical switching is still in the research phase ; however, researchers are looking for ways to create reliable, low loss switches with fast switching speeds. investigation into the possibility of optical packet switching and other novel technologies are currently underway. the all - optical network may be just around the corner. photonic crystal fibers ( pcfs ) photonic crystal fiber ( pcf ) is a subset of photonic crystals. the field of pcf was first explored in the latter half of 1990 ' s and quickly


network may be just around the corner. photonic crystal fibers ( pcfs ) photonic crystal fiber ( pcf ) is a subset of photonic crystals. the field of pcf was first explored in the latter half of 1990 ' s and quickly evolved into a commercial technology. pcfs are generally divided into two main categories : index guiding fibers that have a solid core, and photonic bandgap fibers that have periodic microstructured elements and a core of low index material ( e. g. hollow core ). they can provide characteristics that ordinary optical fiber cannot, such as : single - mode operation from the uv to ir with large mode - field diameters, exceptionally high nonlinearity, numerical aperture ( na ) ranging from very low to about 0. 9, and optimized dispersion properties. applications of pcfs are found in a wide range of research fields like spectroscopy, metrology, biomedicine, imaging, telecommunication, industrial machining, and military. fabrication and characteristicsfigure 12close - up view of pcf preform the typical starting point for manufacturing of an index guided pcf is an array of hollow capillary silica tubes bundled around a pure silica rod replacing the center capillary. for photonic bandgap ( pbg ) fibers, one or more capillary tubes may simply be left out in the center of the preform in order to create a hollow ' defect ' core. a sleeving tube surrounds the entire assembly that forms the preform. in a fiber draw tower, the preform is heated to around 2000°c and it is carefully pulled into fiber with the aid of gravity and pressure. typical outer fiber diameter is 125 µm, but diameters from 80 to around 700 µm are routinely fabricated. this fiber maintains the structure of the preform, but now on a microscopic scale. standard protective polymer coatings are applied to the fibers in order to improve handling characteristics. figure 13most pcf fiber can be connectorized too. call newport for more information. the dispersion characteristics of pcfs can be manipulated to create fibers having zero, low, or anomalous dispersion at visible wavelengths. the dispersion can also be flattened. combining these features with small mode field areas results in outstanding nonlinear fibers. by altering the pattern of air holes or the materials used, it is possible to manipulate other characteristics of pcfs, such as the single - mode cut - off wavelength, the na, and the nonlinear coefficient.


field areas results in outstanding nonlinear fibers. by altering the pattern of air holes or the materials used, it is possible to manipulate other characteristics of pcfs, such as the single - mode cut - off wavelength, the na, and the nonlinear coefficient. the design flexibility is very large, and designers can use many different, fascinating, and odd air hole patterns to achieve specific pcf parameters. the triangular arrangement of round air holes in the cladding is typically used to create single - mode fibers. increasing the air - filling fraction in the cladding typically leads to multimode behavior. an elliptical core can create a highly birefringent fiber that is polarization maintaining. silica provides superior fiber performance for most applications with wavelengths between 200 and 2500 nm, but use of other materials can enhance specific parameters like nonlinearity or wave - guiding outside this spectral region. furthermore, a long list of dopants can be added to silica. doped silica is now used in a variety of fiber lasers and amplifiers ; these could be combined with the unique capabilities of pcfs to provide even more useful devices. coupling, splicing and connectorization of pcfs are other important issues because the fibers may have extreme parameters of mode field area and na ; coupling methods are in some cases very different from standard fiber methods. however, users may strip and cleave the pcfs with standard fiber tools. for laboratory use, the fibers are typically just cleaved and used with " open " ends. in such cases, it is important to avoid direct exposure of the fiber ends to any liquids since the capillary forces in the holes may draw the liquids several centimeters into the fiber, and thus disturb the wave - guiding properties. pcfs can be spliced to standard fibers ( and take advantage of the various connector schemes of such fibers ), or the pcfs may be connectorized directly. newport provides both pcfs spliced to standard fibers and directly connectorized on a semi - custom basis. note that the mechanical strength of splices, the connectorized fiber core offset and connector - to - connector coupling are not always the same as standard fibers. directly connectorized fibers may furthermore provide beam expansion to lower the fiber end facet intensity and reduce the risk of damage at high power levels. call newport for more details. newport ' s f - sm, and f - nl series are index guided fibers. similar to conventional fibers, index guiding pcfs transport light through a solid core by total internal reflection. the microstructured air -


. call newport for more details. newport ' s f - sm, and f - nl series are index guided fibers. similar to conventional fibers, index guiding pcfs transport light through a solid core by total internal reflection. the microstructured air - filled region in pcfs effectively lowers the index of the cladding effectively creating a step - index optical fiber. the fiber behaves in many ways like standard step - index fibers, but it has a number of advantages. index guiding pcfs are made of undoped silica that provides very low losses, sustains high powers and temperature levels, and may withstand nuclear radiation. depending on pcf design, the air in the cladding may be utilized to yield fibers with extremely low or extremely high index steps. figure 14schematic of an index guided pcffigure 15cross section of triangular cladding pcf a typical cross section of an index guided pcf is shown in fig 14 and 15. the pcf consists of a triangular lattice of air holes where the core is defined by a missing air hole. the pitch is labeled λ, and measures the period of the hole structure ( the distance between the centers of neighboring air holes ). the hole size is labeled d, and measures the diameter of the holes. figure 16cross section of air - clad pcf some pcfs have a cladding refractive index that exhibits a strong wavelength dependence. together with the inherently large design flexibility, pcfs allow for a whole range of novel properties to be explored. such properties include endlessly single - mode fibers ( f - sm series ), extremely nonlinear fibers and fibers with anomalous dispersion in the visible wavelength region ( f - nl series ). a unique feature of pcfs is that a single fiber may support single - mode operation over a wavelength range from around 300 nm to beyond 2000 nm even for large mode field areas ( of several hundred µm2 ). this allows pcfs to be utilized for transmission of very high powers with high beam quality without running into nonlinear or damage barriers ( several hundred watts for cw operation ). on the other hand, the highly nonlinear fibers made as single - mode fibers have extremely small mode field areas ( typically around 3 µm2 ) and confine light to the core region efficiently. compared to standard fiber technology, where the light is guided using solid glasses with different refractive indices, several new properties may be realized using pcf technology. for example : - fibers that are single - mode in a very broad spectral range ( in principle all wavelengths )


fiber technology, where the light is guided using solid glasses with different refractive indices, several new properties may be realized using pcf technology. for example : - fibers that are single - mode in a very broad spectral range ( in principle all wavelengths ) - very small mode sizes may be obtained ( down to approx. 1 µm ) - very large mode sizes may be obtained ( up to 25 µm or larger ) - zero dispersion wavelengths below 1300 nm is possible ( down to approx. 600 nm ) - exceptionally large birefringence close to 10 - 2 can be realized - very high numerical apertures up to 0. 9 may be obtained hence, pcfs are ideally suited for applications requiring large non - linearities, broadband operation with single - mode guidance, large mode areas, light collection from a large solid angle, etc. figure 17large mode area fiber ( f - sm series ) figure 18near field image of f - sm fiber at 1550 nmfigure 19mode structure of f - sm20 fiber formation of broad continuous spectra through propagation of short femto or picosecond - range high power pulses through nonlinear media ( also known as supercontinuum generation, or scg ) was first observed in 1970 and has since then been studied extensively in many different materials. the term supercontinuum does not cover a specific phenomenon but rather a plethora of nonlinear effects leading to considerable spectral broadening of optical pulses and thereby potentially octave - spanning output. the involved nonlinear effects depend on the dispersion in the material and count effects like self - phase modulation ( spm ), raman scattering, phase matching and solitons. results on scg in pcfs have previously been presented with pumping in the anomalous dispersion regime or at the zero - dispersion wavelength in both the visible and the infrared wavelength range. most experiments utilize femtosecond pumping as this results in spectacularly broad spectra. picosecond pumping yields more narrow spectra, but does so with far cheaper laser sources and is therefore commercially interesting. although scg can be observed in a drop of water given enough pumping power, pcfs are ideal media for scg as the dispersion can be designed to facilitate continuum generation in a specific region. in this way, it is possible to convert light to both higher and lower wavelength, just like super wide spectra covering more than an octave is achievable at previously unthinkable low power levels. practical super


generation in a specific region. in this way, it is possible to convert light to both higher and lower wavelength, just like super wide spectra covering more than an octave is achievable at previously unthinkable low power levels. practical supercontinuum tips scg - 800 and scg - 800 - cars ( see supercontinuum generation fiber devices ) are ideal in generating supercontinuum using an ultrafast laser. when coupling light from a femtosecond laser into a crystal fiber, a number of issues regarding pulse distortion must be addressed to achieve the optimum performance. in this section, we discuss the precautions taken to couple light from a ti : sapphire laser into a 1. 7 µm core pcf. the first issue to be addressed is the 4 % reflection from the fiber surface, which can lead to a distortion of the pulse train and in severe cases will stop the laser from mode - locking. cleaving the fiber at an angle can minimize back reflections. however, we recommend that the problem be avoided by the use of a faraday isolator. coupling out a small portion of the beam and directing it to newport ' s pulsescout autocorrelators ( see pulsescout autocorrelator ) allows for real - time monitoring of the pulse width and beam quality. the femtosecond pulses are easily coupled into the fiber through standard microscope objectives. magnifications of 40x and 60x provide good results. aspheric ball lenses can also be used, but as these are not achromatic, they should not be used with short femtosecond pulses due to the broad spectral range of these pulses. the dispersion in the microscope objective should be compensated using a precompensating prism or grating compressor in order to launch the shortest possible ( i. e. highest intensity ) pulse into the fiber. the diameter of the laser beam should match the aperture of the microscope objective. this is easily achieved with a standard telescope. nonlinear effects are inherently very sensitive to variations in the input power, thus a very stable mount is needed. to avoid displacement of the fiber end due to thermal, acoustic and other unwanted effects, the fiber should be mounted as close to the end as possible. gluing the fiber to the mount, or using a connectorized fiber, can create further stability. if polarization - maintaining fibers are used, the polarization axis of the linearly polarized femtosecond pulses should


science january 29, 2013 why do grandmothers exist? the question is not as unfeeling as it sounds. from the point of view of the selfish gene, creatures are supposed to drop dead as soon as they lose the power to reproduce. a man can make babies his whole life, even if the sperm of his old age lacks vigor and genetic fidelity. a woman outlives her eggs by about 20 years, which almost no other female mammals do. 1 ( only female killer and pilot whales and orcas are known to last as long after the end of their menstrual cycles. ) besides being classed among the oddities of the animal kingdom, post - menopausal women lack obvious utility. they tend to be weak. they don ' t have much sex appeal. they eat food working people might make better use of. in paraguay ' s ache tribe, aging women used to listen with terror for the footsteps of the young men whose job it was to sneak up on them with an ax and brain them. most societies don ' t actually murder their grannies, but that women manage to attain old age is an evolutionary mystery and requires explanation. are senior citizens really " greedy geezers? " some people deny that women did live past menopause, whether in the pleistocene era or the nineteenth century. before modern hygiene and medicine, the argument goes, people just didn ' t live very long. but most scientists don ' t think that anymore. it is true that, in the olden days, fewer people reached their golden years. children dropped dead with disturbing ease, keeping life - expectancy averages low. but humans still had the capacity to live twice as long as our hominid ancestors. those who got to 15 had about a 60 percent chance of making it to 45, at which point odds were respectable that they ' d reach old age. many anthropologists and biologists now believe that the bodies of homo sapiens were designed to last about 72 years. so why should women stop procreating so early? in 1957, the evolutionary biologist george williams proposed what is called the " stopping - early " hypothesis : middle - age women need baby - free time to usher their youngest children into adulthood. in the 1980s, an american anthropologist named kristen hawkes and two colleagues came up with a different explanation. they had gone to northern tanzania to study the foraging habits of the hadza, the last known hunter - gatherers in africa. while there, the scholars were struck by how strong the tribe ' s old women


colleagues came up with a different explanation. they had gone to northern tanzania to study the foraging habits of the hadza, the last known hunter - gatherers in africa. while there, the scholars were struck by how strong the tribe ' s old women were and how, rather than live off the fruits of others ' labor, they worked hard digging up the tribe ' s main starch staple, a deeply - buried tuber. " their acquisition rates were similar to the rates of younger women, " hawkes told me, " but these old ladies were spending even more time " than their daughters gathering food, leaving camp earlier, coming back later, and bringing back more than they needed. the anthropologists also noticed that many children with grandmothers or great - aunts had faster growth rates than their counterparts. from these slim clues, hawkes and her colleagues developed the " grandmother hypothesis, " which holds that women past childbearing age helped not just their children, but their children ' s children, and lengthened the human lifespan in the process. without babies of their own to lug around, grandmothers had both time and a very good reason to be useful. when they eked out food for their daughters ' children, they reduced the chance that those children would die. that gave the grandmothers a better chance of passing on their own predisposition to longevity. ( in general, grandmothers appear to have helped daughters ' offspring more than sons ' ; evolutionary theorists explain this by pointing out that a daughter ' s maternity affords a surer genetic connection than a son ' s paternity, unless you all but imprison your daughter - in - law. 2 ) the grandmother hypothesis also explains another conundrum : why do humans have shorter birth intervals than other primates? chimp mothers, for instance, wait five or six years to give birth to another neonate. women can pop out infants as soon as they ' ve weaned previous ones. it turns out that, once humans learned the art of collaborative child - rearing, old women started spending more time with their daughters ' toddlers. that freed up the young women to have more. as the grandmother effect spread throughout the population over thousands of generations, it changed humans in another way. it made their brains bigger. as life lengthened, so did each stage of it. children stayed children longer, which let their brains develop a more complex neural architecture. not everyone accepts this triumphantly feminist account of our evolutionary history. when anthropologists first heard it,


bigger. as life lengthened, so did each stage of it. children stayed children longer, which let their brains develop a more complex neural architecture. not everyone accepts this triumphantly feminist account of our evolutionary history. when anthropologists first heard it, most of them dismissed it as ridiculous. for one thing, it cuts man - the - hunter out of the picture. what about all the calories needed to grow our oversized brains? didn ' t those have to come from the meat brought back from the hunt? moreover, throughout recorded history, young women left their villages to move in with their men. so how would mothers have had access to their daughters ' children? the comeback to these objections is that hunter - gatherer families probably made all kinds of arrangements. 3 in the tribes that anthropologists have been able to observe, some couples stayed in the wife ' s village, some moved in with her parents while starting their families, and some women left home. patrilocality — men staying put — probably became the norm only when our ancestors settled down to farm, which made men unwilling to leave their land and wealth. and it ' s not as if hunters alone brought in enough food to let the children thrive. hawkes argues that, while meat boosted a tribe ' s overall nutrition, hunters couldn ' t be counted on to come home with a kill. when they did, the demands of status made them just as likely to share the bounty with the tribe as to hold it back for their children. the food grandmothers provided, on the other hand, was steady and reliable. two decades later, the grandmother hypothesis has gone from oddball conjecture to one of the dominant theories of why we live so long, breed so fast, and are so smart. the extra calories and care supplied by women in their long post - fertile period subsidized the long pre - fertile period that is childhood. and that ' s what made us fully human. in a happy coincidence, the grandmother hypothesis comes along just as americans enter what might be called the age of old age. america ' s biggest generation, the baby - boomers, began retiring in 2011. this gerontocracy is expected to drain our wealth. by 2060, more than 20 percent of all americans will be 65 or older, up from 13 percent in 2010. more than 92 million oldsters will roam the land, if roaming is within their power. people who fret about the federal budget point out that, by 2011, social security and medicare were already eating


or older, up from 13 percent in 2010. more than 92 million oldsters will roam the land, if roaming is within their power. people who fret about the federal budget point out that, by 2011, social security and medicare were already eating up a third of it. looming in the near future is the prospect that both programs ' trust funds will vanish as the number of workers paying into the system goes down. but are senior citizens really " greedy geezers " ( a term made popular by this magazine in 1988 ) about to bankrupt us? the grandmother hypothesis suggests not. it suggests that we should see the coming abundance of over - 65 - year - olds as an opportunity, not a disaster. as gerontologist linda fried, dean of columbia university ' s school of public health, points out, " older adults constitute the only increasing natural resource in the entire world. " 4 if we are going to exploit this resource in the post - industrial world, we ' ll have to use the social capital of the old the way the hadza used them to dig up tubers. mature people of both sexes have a lifetime ' s worth of education and experience. we ' d be crazy to waste that surplus value, especially when so many people languish after retirement, mortified at no longer being needed. to show how much retirees have to offer, fried started a program that puts them in at - risk public schools in 19 cities. early results suggest that children read better and get sent to the principal less often in classrooms where seniors spend 15 hours a week, perhaps because they give teachers support and embarrass students inclined to act up. for their part, the volunteers do better on tests of health and happiness, probably because they like feeling useful. as for actual grandparents, a growing body of research shows how much they help their grandchildren, even when they aren ' t giving them hands - on care or food. often enough, though, they do provide those things, especially in poor families or ones with dysfunctional parents. the number of children being raised by their grandparents has been steadily rising since 2000. in 2011, there were 2. 75 million such children in the united states. but grandparents also give grandchildren more intangible gifts. in the mid - ' 90s, a stanford university fellow named luba botcheva went home to bulgaria to study how grandparents affected families struggling to survive the fall of communism. in the remote and very traditional region where she did her research, several generations would live under the same roof. the


stanford university fellow named luba botcheva went home to bulgaria to study how grandparents affected families struggling to survive the fall of communism. in the remote and very traditional region where she did her research, several generations would live under the same roof. the socialist - era factories had been shut down, and jobs were scarce. botcheva discovered that grandparents ' pensions were often the most dependable source of a household ' s income. in addition to paying the bills, however, grandparents buffered grandchildren against the harsh parenting that comes from acute anxiety. children who grew up with grandparents in the home reported less depression than those without. " it was the opposite of what we expected, " she said. " i called it the ' moderation effect. ' " many of the grandparents had lived through world war ii, so when it came to poverty and uncertainty about the future, they had " social wisdom " to share, as botcheva puts it, which kept tension levels down. 5 unsurprisingly, grandmothers often do more for their grandchildren than grandfathers do. " older women are the neighborhood watch and the neighborhood glue, " says fried. " they ' re the community purveyor of norms. " when older black people in south africa first started getting pensions from the post - apartheid government that were big enough to live on, the grandchildren who lived with grandmothers — especially the granddaughters — got taller and heavier, which observers took as a sign that they were eating better. 6 but when it was the grandfathers who got the pensions, the grandchildren didn ' t grow at all. that wouldn ' t surprise economists who work with microfinance lending programs. they have discovered that female borrowers use their loans to improve their children ' s lot, whereas male borrowers, on the whole, do not. not that all grandparents can or want to be useful. as more people in industrialized countries postpone childbearing, parents become grandparents later and have less energy. the divorced ones may have started second or third families of their own. global mobility puts distance between the generations. assisted - living facilities segregate the old. some retirement communities bar children altogether. but children still need the nurture they once got from their mothers ' mothers. so it ' s worth thinking, along with fried, about institutions that would give parents and children that grandparental boost. i dream of communal houses or apartment complexes where families could live near grandparents but not right on top of them. that vision gives rise to others, some of


first a meteor exploded over russia, followed closely by an asteroid fly - by. now, two comets are expected to put on a naked - eye spectacle for sky watchers in the northern hemisphere. up first is comet pan - starrs, which gets its funky name from the telescope credited with discovering it in june 2001 : the panoramic survey telescope & rapid response system in hawaii. the comet is already visible through telescopes in the southern hemisphere, and it should swing into view over the northern hemisphere beginning around march 8. it ' s hard to predict exactly how bright pan - starrs will be, but you should be able to see it without binoculars or telescopes, said don yeomans of nasa ' s near - earth object program. it should be about as bright as the stars in the big dipper. " there is a chance that it will be a little brighter than this, but likewise, it might not get quite that bright, " said karl battams of the naval research lab. part of the brightness will depend on how close pan - starrs gets to the sun. comets are made up of water, ice, dust and other elements and minerals, all loosely packed together, battams said. as a comet gets closer to the sun, the sun ' s heat causes these elements to melt, spewing out dust and gas in a brilliant tail. " the closer it gets, the more intense the radiation and the more elements will be melted, " he said. pan - starrs is expected to get fairly close to the sun. that ' s bad news for the comet, but it could be a boon for sky watchers if the comet is brighter and easier to see. pan - starrs also could fall apart and fizzle. but if it survives its sunbath, we should be able to see it low on the horizon in the western sky for a couple of weeks, battams said. " about half an hour after sunset would be a good time for people take a look, " he said. here are some key dates : march 5 : pan - starrs will be closest to earth ; march 10 : the comet will pass closest to the sun ; march 12 and 13 : the best dates to look for pan - starrs ; it should emerge in the western sunset sky not far from the crescent moon. battams has these viewing tips : 1 ) safety first : don ' t try to look at the comet until the sun sets. do not look at the sun using regular binoculars or telescopes


the avant - garde movements of the early 20th century ushered in a revolution on many fronts : a revolution in the arts, a revolution in political values, and a revolution in thinking itself. in this course, we examine central literary and artistic works of the european avant - garde, studying the movements of italian futurism, german expressionism, dada, and french surrealism. at the heart of this course is an inquiry into the crucial nexus of art and politics. what constitutes the central critiques made by the various avant - garde movements? in what ways did these movements induce social and political change? what legacy have they left on our thinking today? finally, what can we make of the complexities of the avant - garde? how can we understand the futurist leaning toward fascism, the anarchist stance in dada, and the gender violence in expressionist art and literature? attention is paid to the visual and verbal arts. we read the genres of poetry, prose, and drama, as well as manifestoes and political tracts. we also view slides of painting, photography, photomontage and performance art. works by andr breton, leonora carrington, franz kafka, mina loy, f. t. marinetti, tristan tzara, and frank wedekind, amongst others. theoretical texts by walter benjamin, bertolt brecht, peter brger, and georg lukcs.


water from space is ' raining ' onto a planet - forming disc at supersonic speeds, new observations from the spitzer space telescope reveal. the unprecedented detail of the observations at this early stage of the disc ' s formation could help reveal which of two competing theories of planet formation is correct. planets form when matter clumps together in swirling discs of gas and dust, called protoplanetary discs, around infant stars. but many details of how this works are still not known. for example, some scientists think giant planets can form in just a few thousand years, while others argue it takes millions of years. now, astronomers led by dan watson of the university of rochester in new york, us, have gained an unprecedented view of a protoplanetary disc at the young age of just a few hundred thousand years old. they used the spitzer space telescope to examine the spectrum of infrared light coming from the vicinity of an embryonic star called iras 4b, which lies about 1000 light years from earth. at this very early stage, an outer cocoon of gas and dust called an envelope still surrounds the star and its swirling disc. previous observations in the microwave portion of the spectrum suggested that this large cocoon is contracting and sending material onto the disc. but the inner region, where the disc meets the cocoon, could not be seen at these wavelengths. the spitzer observations probe this inner region and reveal infrared light emitted by massive amounts of water vapour - the equivalent of five times the content of the earth ' s oceans. the vapour is too hot to be explained by the embryonic star ' s radiation alone, suggesting another process must be heating it up. the team believes ice from the cocoon is pelting the disc at a rate faster than the speed of sound there, creating a shock front. " the sonic boom that it endures when it lands on the disc heats it up very efficiently " and vaporises it, watson told new scientist. this supersonic shock " has been searched for and theorised about for decades ", watson says. it is a short - lived phenomenon that only occurs during the first few hundred thousand years of the star and disc formation, while the envelope is still feeding the disc. the light emitted as the icy particles hit the disc can be used to learn more about the disc itself at this early stage, which could shed light on how planets form. most astronomers believe planets form according to a model known as " core accretion ", in which small particles snowball into larger and larger


used to learn more about the disc itself at this early stage, which could shed light on how planets form. most astronomers believe planets form according to a model known as " core accretion ", in which small particles snowball into larger and larger objects over millions of years. a competing idea, called " disc instability ", is that turbulence in the disc can cause matter to collapse into planets extremely quickly, producing gas giants such as jupiter in just a few thousand years. " if you wanted to test between those scenarios, one of the most important places to look would be the stage we ' re looking at now, " watson says. future observations of such young discs could reveal how turbulent the discs are, and thus whether they boast the conditions required for disc instability, he says. " the whole subject of the very beginnings of the development of solar systems is open to study now, " watson says. donald brownlee of the university of washington in seattle, us, agrees. " it ' s interesting to have a new peek into a period of history of what appears to be a forming planetary system, potentially at a timescale that we ' ve never seen before, " he told new scientist. " it forms another important clue to how planetary systems form. " journal reference : nature ( vol 448, p 1026 ) if you would like to reuse any content from new scientist, either in print or online, please contact the syndication department first for permission. new scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to. have your say only subscribers may leave comments on this article. please log in. only personal subscribers may leave comments on this article barking up the wrong tree mon mar 19 19 : 02 : 04 gmt 2012 by tony marshallsay having been schooled in the theory of planet formation by agglomeration of dust particles over a period of thousands or millions of years, i have recently ceased believing in it for a number of reasons : 1. if agglomeration works so well, why has the asteroid belt not agglomerated to a planet? of course, recent examination by spacecraft has revealed that, while some asteroids are solid, other " potatoes " are, indeed, agglomerates. 2. the agglomeration theory cannot easily - if at all - explain retrograde planetary spins 3. it is difficult to see how agglomeration and an exceedingly slow increase in self - gravity pressure could result


agglomerates. 2. the agglomeration theory cannot easily - if at all - explain retrograde planetary spins 3. it is difficult to see how agglomeration and an exceedingly slow increase in self - gravity pressure could result in the creation of " rocky " planets like our earth, with molten iron cores including heavier, radioactive elements to generate internal heating, since any heat generated by the compression process would be dissipated into space over such a long time, making fusion reactions extremely unlikely. accordingly, i have come to the opinion that planets of all types are formed initially not over an exceedingly long time but rather almost instantly as core shards of exploding supernovae. this view, again, has several implications, viz : a. outer core shards consisting of light materials would likely be small, lose heat very quickly and cool into misshapes before being able to become spherical under self - gravity. b. inner core shards, on the other hand, would have sufficient thermal capacity and radioactive material to maintain heat long enough to develop a spherical shape and the composition of our earth ( we might thus consider the earth to be a microcosm of a stellar core, albeit under far less heat and pressure ). c. the shards would be flung in all directions, resulting in the multitude of " free planets " recently observed by japanese investigators. d. some of those free planets would inevitably - sooner or later - become trapped in the gravitational fields of stars, creating planetary systems, such as our own solar system. e. the inconsistencies of size and composition of the solar system ' s planets can then easily be explained by considering the planets as having been captured " missiles " from various supernovae, perhaps even in other galaxies ( do the math - it ' s possible, even at incredibly slow speeds, when you take a few billion years into consideration ). f. a " gas giant " can be formed by a heavy, rocky " seed " gathering a thick coat of gas through happening to have been ejected in the direction of a large gas cloud. opinions on the above are welcome ( i am becoming accustomed to brickbats descending upon my head from a great height! ). all comments should respect the new scientist house rules. if you think a particular comment breaks these rules then please use the " report " link in that comment to report it to us. if you are having a technical problem posting a comment, please contact technical support.


american civil religion american civil religion is a term given to a shared set of certain fundamental beliefs, values, holidays, and rituals by those who live in the united states of america. these shared values and holidays are based upon, parallel to, but independent of the theological tenets of each specific denomination or religious belief. the notion of a civil religion originated in the united states due to its origins as a religiously diverse nation. from the pilgrim founders and the other puritan groups to the numerous other groups fleeing religious persecution, the american nation had a unique experience and developed a system that allowed for maximum freedom of religion for individuals and groups while allowing no one religious denomination to dominate. in this context, the nation developed a religious, primarily protestant ethos and set of values based on religion but not overtly based on any one tradition. the term was coined by sociologist robert bellah in 1967. the article in which the term is coined, " civil religion in america, " sparked one of the most controversial debates in united states sociology. soon after the paper was published, the topic became the major focus at religious sociology conferences and numerous articles and books were written on the subject. the debate reached it peak with the american bicentennial celebration in 1976. the american civil religion emerged as a means to permit the creation of a distinct national set of values that was not tied to a specific confession. it permitted religion to play a fundamental role in shaping the moral vision of the country but in a way that removed theological concerns from the public arena. the united states was settled in part by religious dissenters from the established church of england, who desired a civil society founded on a different religious vision. consequently, there has never been a state church in the united states and individual state churches have not existed in the united states since the early nineteenth century. religious denominations compete with one another for allegiance in the public square. these facts have created a public discourse which accepts regular displays of religious piety by political leaders but in a vocabulary which captures the common values embraced by diverse religious traditions but eschews the particular theological tenets. unlike countries with established state churches, where the specific religious basis of political discourse is held in common and therefore taken for granted, american civil society developed a way of discussing the intersection of religious and political values in non - theological terms. three periods of crisis in the book the broken covenant bellah argued that america has experienced three periods when a large number of americans were cynical about the american creed : once in each of the last three centuries america has faced a time


non - theological terms. three periods of crisis in the book the broken covenant bellah argued that america has experienced three periods when a large number of americans were cynical about the american creed : once in each of the last three centuries america has faced a time of trial, a time of testing so severe that … the existence of our nation has been called in question … the spiritual glue that had bound the nation together in previous years had simply collapsed. creation of the term bellah ' s ideas about civil religion were not novel. before bellah wrote his paper in 1967 coining the term " american civil religion " several prominent scholars had alluded to the concept. but there was no common conceptual term to describe, interpret or analyze civic religious faith in america. alexis de tocqueville the french thinker alexis de tocqueville has a special place in the understanding of the role of religion in american history. in addition to defining the economic factors that separated british culture from that of the americans, tocqueville found the role of religion in these societies to be significantly different. he found that many of the differences between the americans and the english stemmed from diverse spiritual practices and freedoms. in democracy of america tocqueville stated : religion in american takes no direct part in the government of society, but it must be regarded as the first of their political institutions ; for if it does not impart a taste for freedom, it facilitates the use of it. indeed, it is in this same point of view that the inhabitants of the united states themselves look upon religious belief. i do not know whether all americans have a sincere faith in their religion for who can search the human heart? — but i am certain that they hold it to be indispensable to the maintenance of republican institutions. this opinion is not peculiar to a class of citizens or to a party, but it belongs to the whole nation and to every rank of society. throughout his career, tocqueville promoted the importance of religious freedom and education without religious influence. the importance he placed on educational innovation led to his strong defense of religious freedom : they all attributed the peaceful dominion of religion in their country mainly to the separation of church and state. i do not hesitate to affirm that during my stay in america i did not meet a single individual, of the clergy or the laity, who was not of the same opinion on this point. he viewed religious independence as not a threat to society, but as an inspiration for further social freedoms, and believed the basic freedoms of education,


single individual, of the clergy or the laity, who was not of the same opinion on this point. he viewed religious independence as not a threat to society, but as an inspiration for further social freedoms, and believed the basic freedoms of education, religion, and the press to ultimately foster the spirit of freedom worldwide. yet tocqueville believed religion to be essential to human success, particularly in democracies : despotism may govern without faith, but liberty cannot. religion is much more necessary in the republic … than in the monarchy … it is more needed in democratic republics than in any others. how is it possible that society should escape destruction if the moral tie is not strengthened in proportion as the political tie is relaxed? and what can be done with a people who are their own masters if they are not submissive to the deity? tocqueville saw in america the realization of the idea that inspired him. scholarly progenitors of this idea include john dewey who spoke of " common faith " ( 1934 ) ; robin williams ' s american society : a sociological interpretation, ( 1951 ) which stated there was a " common religion " in america ; lloyd warner ' s analysis of the memorial day celebrations in " yankee city " ( 1953 ) ; martin marty ' s " religion in general " ( 1959 ) ; will herberg who spoke of " the american way of life " ( 1960, 1974 ) ; sidney mead ' s " religion of the republic " ( 1963 ) ; and g. k. chesterton advanced the thesis that the united states was " the only nation … founded on a creed " and also coined the phrase " a nation with a soul of a church. " in the same period, several distinguished historians such as yehoshua arieli, daniel boorstin, and ralph gabriel " assessed the religious dimension of ' nationalism ', the ' american creed ', ' cultural religion ' and the ' democratic faith ' ". today, according to social scientist rondald wimberley and william swatos, there seems to be a firm consensus among social scientists that there is a part of americanism that is especially religious in nature, which may be termed " civil religion. " but this religious nature is less significant than the " transcendent universal religion of the nation " which late eighteenth century french intellectuals such as jean - jacques rousseau and alexis de tocqueville wrote about. robert bellah and colleagues bellah and fellow scholar martin e. marty studied civil religion as a cultural phenomenon, attempting to identify the actual ten


which late eighteenth century french intellectuals such as jean - jacques rousseau and alexis de tocqueville wrote about. robert bellah and colleagues bellah and fellow scholar martin e. marty studied civil religion as a cultural phenomenon, attempting to identify the actual tenets of civil religion in the united states of america, or to study civil religion as a phenomenon of cultural anthropology. marty wrote that americans approved of " religion in general " without being particularly concerned about the content of that faith, and attempted to distinguish " priestly " and " prophetic " roles within the practice of american civil religion, which he preferred to call the " public theology. " bellah wrote that civil religion was " an institutionalized collection of sacred beliefs about the american nation. " he identified the american revolution, the civil war, and the civil rights movement as three decisive historical events that impacted the content and imagery of civil religion in the united states. he also identified several modalities within u. s. civil religion related to the biblical categories of the priesthood, prophets, and wisdom tradition. empirical evidence supporting bellah ronald wimberley ( 1976 ) and other researchers collected large surveys and factor analytic studies which gave empirical support to bellah ' s argument that civil religion is a distinct cultural phenomena within american society which is not embodied in american politics or denominational religion. examples of civil religious beliefs are reflected in statements used in the research such as the following : - " america is god ' s chosen nation today. " - " a president ' s authority... is from god. " - " social justice cannot only be based on laws ; it must also come from religion. " - " god can be known through the experiences of the american people. " - " holidays like the fourth of july are religious as well as patriotic. " later research sought to determine who embraces views that could be characterized as part of the american civil religion. in a 1978 study by james christenson and ronald wimberley, the researchers found that a wide cross section of american citizens have such beliefs. in general though, college graduates and political or religious liberals appear to be somewhat less likely to embrace civil religion. protestants and catholics have the same level of civil religiosity. religions that were created in the united states, the mormons, adventists, and pentecostals, have the highest civil religiosity. jews, unitarians and those with no religious preference have the lowest civil religion. even though there is variation in the scores, the " great majority " of americans


adventists, and pentecostals, have the highest civil religiosity. jews, unitarians and those with no religious preference have the lowest civil religion. even though there is variation in the scores, the " great majority " of americans are found to share the types of civil religious beliefs which bellah identified. further research found that civil religion plays a role in people ' s preferences for political candidates and policy positions. in 1980 ronald wimberley found that civil religious beliefs were more important than loyalties to a political party in predicting support for nixon over mcgovern with a sample of sunday morning church goers who were surveyed near the election date and a general group of residents in the same community. in 1982 james christenson and ronald wimberley found that civil religion was second only to occupation in predicting a person ' s political views. while some have argued that christianity is the national faith … few have realized that there actually exists alongside … the churches an elaborate and well - institutionalized civil religion in america - robert bellah civil religion is neither bona fide religion nor ordinary patriotism, but a new alloy formed by blending religion with nationalism. if civil religions were bona fide religions then one would expect to find a soft side to them, teaching love of neighbor and upholding peace and compassion. but this is not the case. - stjepan mestrovic all links retrieved july 7, 2008. - ↑ 1. 0 1. 1 1. 2 robert neelly bellah, " civil religion in america " journal of the american academy of arts and sciences 96 ( 1 ) ( winter 1967 ) : 1 – 21 from the issue entitled " religion in america ". - ↑ dana evan kaplan. the cambridge companion to american judaism. ( cambridge university press, 2005. isbn 0521822041 ), 118. - ↑ stjepan mestrovic. the road from paradise. ( university press of kentucky, 1993 isbn 0813118271 ), 129 - ↑ 4. 0 4. 1 4. 2 4. 3 4. 4 marcela cristi. from civil to political religion : the intersection of culture, religion and politics. ( university press, 2001 isbn 0889203687 ) - ↑ 5. 0 5. 1 5. 2 5. 3 5. 4 5. 5 5. 6 william h. swatos. encyclopedia of religion and society. ( rowman altamira, 1998. isbn 0761989560 ), 94.


. 1 5. 2 5. 3 5. 4 5. 5 5. 6 william h. swatos. encyclopedia of religion and society. ( rowman altamira, 1998. isbn 0761989560 ), 94. " the article caused an almost unprecedented burst of excitement among sociologists and other scholars of religion. " - ↑ richard t. hughes. myths america lives by. ( university of illinois press, 2004. isbn 0252072200 ), 3 - ↑ robert neelly. the broken covenant : american civil religion in time of trial. ( university of chicago press, 1992 ), 1 - ↑ french ministry of culture, alexis de tocqueville. general council for la manche. retrieved june 4, 2007. - ↑ gerald a. parsons, " from nationalism to internationalism : civil religion and the festival of saint catherine of siena, 1940 - 2003. " journal of church and state ( september 22, 2004 ) - ↑ stjepan gabriel mestrovic. the road from paradise : prospects for democracy in eastern europe. ( university press of kentucky, 1993. isbn 0813118271 ), 125, 130 american civil religion - bellah, robert neelly, " civil religion in america. " journal of the american academy of arts and sciences 96 ( 1 ) ( winter 1967 ) : 1 – 21. from the issue entitled religion in america. - bellah, robert neelly. the broken covenant : american civil religion in time of trial. university of chicago press, 1985. isbn 0226041999 - canipe, lee, " under god and anti - communist : how the pledge of allegiance got religion in cold - war america. " journal of church and state ( march 22, 2002. } - cloud, matthew w., " one nation, under god " : tolerable acknowledgment of religion or unconstitutional cold war propaganda cloaked in american civil religion? " journal of church and state 46 ( 2 ) ( march 22, 2004 ) : 311 issn 0021 - 969x. - edwords, frederick, " the religious character of american patriotism. " the humanist ( november / december 1987 ) : 20 – 24, 36 - gehrig, gail. american civil religion : an assessment. society for scientific study, 1981. isbn 0932566022 - hughes, richard t. myths america lives by. university of illinois press, 2004. isbn 0252072200 - jewett,


. american civil religion : an assessment. society for scientific study, 1981. isbn 0932566022 - hughes, richard t. myths america lives by. university of illinois press, 2004. isbn 0252072200 - jewett, robert, and john shelton lawrence. captain america and the crusade against evil : the dilemma of zealous nationalism. grand rapids, mi : wm. b. eerdmans publishing, isbn 0802828590, specifically talks about american civil religion, referencing jones ' s book, american civil religion. 328. - jones, donald g. and russell e. richey. american civil religion. mellen university press, 1990 ( original published in 1974 by harper ). isbn 0773499970 - mathisen, james a. " twenty years after bellah : whatever happened to american civil religion? " sociological analysis 50 ( 2 ) ( 1989 ) : 29 – 46 - levinson, sanford, 1979 " the constitution " in american civil religion. " the supreme court review ( 1979 ) : 123 – 151. - luckmann, thomas. the invisible religion. 1967 published the same year as bellah ' s article. - neelly, robert. the broken covenant : american civil religion in time of trial, second ed. university of chicago press, 1992. isbn 0226041999 - swatos, william h., encyclopedia of religion and society. altamira press, 1998, isbn 0761989560, 95. civil religion entry - further information : american exceptionalism - churchill, ward. " the ghosts of 9 - 1 - 1 : reflections on history, justice and roosting chickens. " ( spring 2005 ) - lipset, seymour martin. american exceptionalism : a double - edged sword. new york : w. w. norton & company, 1997. isbn 0393316149 - book reviews of : seymour martin lipset ' s american exceptionalism : a double - edged sword part 1, the washington post, the weekly standard, ', foreign affairs, ', the guardian, new statesman & society, etc.. accessdate 2008 - 07 - 07. - zinn, howard. " the power and the glory myths of american exceptionalism. " bostonreview. net accessdate 2006 - 07 - 16 new world encyclopedia writers and editors rewrote and completed the wikipedia article in accordance with new world encyclopedia standards. this article abides by terms of the creative commons cc - by - sa


a. synoptic history an extratropical low pressure system formed just east of the turks and caicos islands near 0000 utc 25 october in response to an upper level cyclone interacting with a frontal system. the low initially moved northwestward, and in combination with a strong surface high to the north developed into a gale center six hours later. by 1800 utc that day it had developed sufficient organized convection to be classified using the herbert - poteat subtropical cyclone classification system, and the best track of the subtropical storm begins at this time ( table 1 and figure 1 ). upon becoming a subtropical storm, the cyclone turned northward. this motion continued for 24 h while the system slowly intensified. the storm jogged north - northwestward late on 26 october, followed by a north - northeastward turn and acceleration on the 27th. during this time, satellite imagery indicated intermittent bursts of central convection while air force reserve hurricane hunter aircraft indicated a large ( 75 - 100 n mi ) radius of maximum winds. this evolution was in contrast to that of hurricane michael a week - and - a - half before. although of similar origin to the subtropical storm, michael developed persistent central convection and completed a transition to a warm - core hurricane. after reaching a 50 kt intensity early on 27 october, little change in strength occurred during the next 24 h. the storm turned northeastward and accelerated further on the 28th in response to a large and cold upper - level cyclone moving southward over southeastern canada. a last burst of organized convection late on the 28th allowed the storm to reach a peak intensity of 55 kt. a strong cold front moving southward off the new england coast then intruded into the system, and the storm became extratropical near sable island, nova scotia, around 0600 utc 29 october. the extratropical center weakened rapidly and lost its identity near eastern nova scotia later that day. it should be noted that the large cyclonic circulation that absorbed the subtropical storm was responsible for heavy early - season snowfalls over portions of the new england states and b. meteorological statistics table 1 shows the best track positions and intensities for the subtropical storm, with the track plotted in figure 1. figure 2 and figure 3 depict the curves of minimum central sea - level pressure and maximum sustained one - minute average " surface " ( 10 m above ground level ) winds, respectively, as a function of time. these figures also contain the data on which the curves are based : satellite - based hebert - poteat and experimental extratropical transition intensity ( miller and lander, 1997 )


above ground level ) winds, respectively, as a function of time. these figures also contain the data on which the curves are based : satellite - based hebert - poteat and experimental extratropical transition intensity ( miller and lander, 1997 ) estimates from the tropical analysis and forecast branch ( tafb ), the satellite analysis branch ( sab ) of the national environmental satellite data and information service ( nesdis ), and the air force weather agency ( afwa ), as well as data from aircraft, ships, buoys and land stations. the air force reserve hurricane hunters flew two mission into the storm with a total of four center fixes. central pressures on both flights were in the 997 - 1000 mb range, and the maximum flight level ( 1500 ft ) winds were 60 kt on the first flight and 61 kt on the second. a weak temperature gradient was observed in the system on the first flight, suggesting that the cyclone still had some baroclinic characteristics. the second flight showed a uniform airmass within 100 n mi the center with temperatures of about the storm had a large envelope, and many ships reported 34 kt or higher winds. table 2 summaries these observations. there were few observations near the central core. canadian buoy 44137 reported winds 160 / 39 kt with a pressure of 979. 1 mb at 0200 utc 29 october, which is the basis for the lowest pressure. other reports from this buoy indicate that the winds increased in the last hour before the center passed, suggesting that some kind of inner wind maximum was present even as the storm was becoming extratropical. earlier, a drifting buoy about 35 n mi southeast of the center reported a pressure of 996. 6 mb at 2051 utc 27 october, which showed that the storm had begun to deepen. sable island, nova scotia, reported a pressure of 980. 6 mb as the center passed over at 0600 utc on the 29th. maximum sustained winds were 35 kt after the center passage at 0700 and 0800 utc. several other stations in eastern nova scotia and southwestern newfoundland reported sustained 35 - 50 kt winds around 1200 utc on the 29th. the maximum intensity of this system is uncertain. satellite intensity estimates late on the 28th and early on the 29th along with a 35 - 40 kt forward motion indicate the possibility of 65 - 75 kt sustained winds. however, this is not supported by surface observations near the center early on the 29th. the maximum intensity is estimated to have been 55 k


29th along with a 35 - 40 kt forward motion indicate the possibility of 65 - 75 kt sustained winds. however, this is not supported by surface observations near the center early on the 29th. the maximum intensity is estimated to have been 55 kt. c. casualty and damage statistics no reports of casualties or damage have been received at the national hurricane center ( nhc ). d. forecast and warning critique no advisories were written on this storm, as a decision was made operationally to handle it in marine forecasts as an extratropical storm. post - analysis of satellite imagery and of 27 october aircraft data are the basis for classifying the system now as subtropical. due to the operational handling, there are no formal nhc forecasts to verify. large - scale numerical models generally performed well in forecasting the genesis and motion of this cyclone. the models did mostly underestimate the intensification that occurred north of the gulf stream. however, this strengthening was fairly well forecast by the gfdl model. no tropical cyclone watches or warnings were issued for this storm. marine gale and storm warnings were issued in high seas and offshore forecasts from marine prediction center and the tafb of the tpc. gale warnings were also issued for portions of the north carolina coastal waters by local national weather service offices. miller, d. w and m. a. lander, 1997 : intensity estimation of tropical cyclones during extratropical transition. jtwc / satopstn - 97 / 002, joint typhoon warning center / satellite operations, nimitz hill, guam, 9 pp. best track, subtropical storm, 25 - 29 october 2000. | lat. ( °n ) | | lon. ( °w ) | 25 / 0000 | | 21. 5 | | 69. 5 | | 1009 | | 30 | | extratropical low | | 25 / 0600 | | 22. 5 | | 70. 0 | | 1007 | | 35 | | extratropical gale | | 25 / 1200 | | 23. 5 | | 70. 9 | | 1006 | | 35 | | " | | 25 / 1800 | | 24. 5 | | 71. 7 | | 1005 | | 35 | | subtropical storm | | 26 / 0000 | | 25. 7 | | 71. 7 | | 1004 | | 35 | | " | | 26 / 0600 | | 26. 6 | | 71. 7 | | 1003 | | 35 | | " | | 26


silver birch tree © bob press slender, open crowned tree up to 30m tall but usually about half this size. the large branches are pointed upwards but the smaller ones and twigs are hanging down, giving a graceful, weeping appearance. silvery white, developing large black diamond - shaped fissures. young shoots have pale warts. roughly oval or triangular to diamond - shaped with a tapered tip and rounded. the edges are toothed or double - toothed. both surfaces are dotted with tiny glands. slender males are loosely hanging and pale yellow. female catkins are 2 – 3cm long and stand upright. they are loosely hanging and break up when ripe to release small, winged seeds. silver birch leaves and catkins. © robert videki, doronicum kft., hungary silver birch tree bark. © universita di trieste, dipartimento di biologia. photo : andrea moro silver birch tree bark. © bob press silver birch tree cones. © tom degomez, university of arizona, united states silver birch tree. © bob press these diagrams explain some of the important tree and plant parts. these diagrams show the different leaf shapes you might come across on your survey. leaf shapes are important for identifying trees. the way leaves are arranged on a stem can be important for identifying trees. these definitions explain some of the trickier words and phrases used in these pages. alternate – the arrangement of leaves on a stem - the leaves attach at different but alternating points, rather than opposite points. anther – the part of the stamen that contains pollen. apex – the top or end ; the tip of a leaf for example. bract – a leaf - like structure, usually found below the flower or fruit. bud scale – usually a type of modified leaf that encloses and protects a bud. catkin – slender inflorescences made up of small flowers, usually reduced to the male and female parts. catkins are typical of wind - pollinated trees. coniferous – trees that have cones, and needle or scale - like leaves. crown – in a tree, everything above the trunk. deciduous – a tree that sheds its leaves all at once in the autumn. evergreen – a tree that retains its leaves all year round. girth – the circumference of something, like the trunk of a tree. gland ( of a leaf ) – a small organ on a leaf that gives out oils or similar substances. inflorescence – the arrangement of all the flowers on a


##rth – the circumference of something, like the trunk of a tree. gland ( of a leaf ) – a small organ on a leaf that gives out oils or similar substances. inflorescence – the arrangement of all the flowers on a tree. the shape is used to help identify the plant. key – a tool used to identify groups and species of living things. leaflet – a subdivision of a leaf - it may look like a leaf but is attached to the leaf stalk or midrib, not to the shoot. lobe – a rounded or pointed section of a leaf, not divided into a leaflet. margin – the edge of a leaf. midrib – the central vein of a leaf. native – a tree that occurs naturally in an area, as opposed to a non - native tree that has been introduced. opposite – the arrangement of leaves on a stem - the leaves attach in pairs at the same point, opposite each other, rather than attaching at alternate points. palmate – a leaf shape in which the lobes or leaflets radiate from a single point, like fingers from a hand. petals – usually larger and more brightly coloured than sepals. pinnate – a leaf shape in which the lobes or leaflets are arranged on both sides of the stalk or midrib like a feather. pollarded – when the upper branches of a tree have been cut back to encourage new growth. sepals – the outermost parts of a flower which cover and protect the flower when it is in bud. they are usually green. side shoots – short, spur - like shoots growing from the main shoots. spike – an elongated cluster of flowers ; a type of inflorescence. stalk – the structure that supports the blade of a leaf. stigma – the part at the end of the style. it is covered with a sticky substance that pollen adheres to. stipule – a small, leaf - like structure, found where the leaf connects to the stem. style – a tube - like structure in the centre of a flower that supports the stigma. trunk – the woody stem of a tree, before the branches. urban forest – the trees in our towns and cities. whorl – 3 or more leaves or needles circling around a stem.


tuesday, november 29, 2011 bob kuska, nidcr mouse study explains bacterium ' s unique role in periodontitis nih - supported study solves the mystery of a devious oral bacterium scientists say they have solved in mice the mystery of how an unusual bacterium can trigger the common dental condition periodontitis while residing in low numbers in the space between tooth and gum. the researchers report that the microbe porphyromonas gingivalis hacks into the front - line immune cells that police the space between tooth and gum, known as the subgingival crevice, and reprograms them to create living conditions more to its microbial liking. as more immune cells are co - opted to follow the wrong program, the usually benign bacterial residents of the subgingival crevice — not p. gingivalis, as long suspected — opportunistically rise up in number, altering their community dynamics and prompting them to infect the tooth ' s supportive structures, or periodontium. the study in the nov. 17 issue of the journal cell host and microbe was supported by the national institute of dental and craniofacial research ( nidcr ), part of the national institutes of health. " as the other bacteria attack, and immune cells counterattack, progressively damaging the integrity of the tooth in the process, p. gingivalis sits in the shadows and feasts on the inflammatory spoils, " said george hajishengallis, d. d. s., ph. d., a researcher at the university of louisville school of dentistry and a co - lead author on the study. " this is one ingenious little bug. " according to hajishengallis, their discovery marks the first documented case in microbiology of a keystone species, or more specifically, a keystone pathogen. coined by ecologists in the late 1960s, the keystone concept refers to a low - abundance species that exercises a disproportionate influence on its environment. in this case, low - abundance p. gingivalis shapes a microbial community and catalyzes the onset of an oral disease. the next step is to test whether p. gingivalis follows a comparable evolutionary strategy in people. if so, they already have in their sights drugs that can be applied topically to the affected tooth to block this keystone pathogen from reprogramming the immune cells, providing a more targeted approach to prevent and / or treat periodontitis


people. if so, they already have in their sights drugs that can be applied topically to the affected tooth to block this keystone pathogen from reprogramming the immune cells, providing a more targeted approach to prevent and / or treat periodontitis. periodontitis has afflicted humans from time immemorial, and today remains one of the most common causes of tooth loss worldwide. an estimated 53 million american adults have the condition, approximately 2 out of every 10 adults, at a total annual healthcare expenditure of more than $ 14 billion. in the late 1970s, p. gingivalis became a subject of research interest when scientists noticed this rod - shaped anaerobe popping up consistently at low levels in studies that explored the microbiology of periodontitis. further laboratory work showed that this late colonizer of the subgingival crevice arrives bearing an extensive arsenal of noxious chemicals. the assumption being, p. gingivalis employs them selectively to thwart the native, or innate, immune cells that patrol the gingival crevice and keep bacterial levels in balance. but showing that p. gingivalis actually can cause periodontitis has remained scientifically tricky. the assumption has been that the bacterium could directly cause damage to the periodontium in animal models, independent of periodontitis and its natural disease process. moreover, scientists have found themselves traversing new conceptual territory to explain how such a low - abundance — some say stealth — pathogen could wreak such havoc in the mouth. the research story has picked up in recent years as scientists have gained more technologically sophisticated tools to study p. gingivalis, and more biological information from which to form workable hypotheses. a case in point is the progress in understanding how immune cells process incoming information to respond to the threat at hand. studies show that some incoming defense signals converge within innate immune cells, a process called signaling crosstalk, which helps them to coordinate their early internal response to infection. last year, hajishengallis and colleagues reported in mouse studies that p. gingivalis has learned through the millennia to exploit this crosstalk. the bacterium does so by jointly activating convergent defense signals involving the toll - like receptor 2 ( tlr - 2 ), which helps to recognize pathogens, and the c5a receptor that is a part of the complement system that will respond to the threat. " p. gingivalis exploits both receptors to induce a signal with an emergent


- 2 ), which helps to recognize pathogens, and the c5a receptor that is a part of the complement system that will respond to the threat. " p. gingivalis exploits both receptors to induce a signal with an emergent property, " explained hajishengallis. " in other words, the property doesnit emerge from manipulating just one receptor. both must be punched. " hajishengallis said the emergent property impairs the affected immune cell from killing p. gingivalis. it also seems to initiate low - level inflammation that serves no immunological purpose other than possibly to generate nutrients for p. gingivalis. this discovery pointed to an evasion mechanism that p. gingivalis employs to subvert innate immunity. left unanswered was the larger question of whether this stealth mechanism also played a role in causing periodontitis. to get their answer, the scientists revisited two unexplained laboratory observations. first, after mice are inoculated with p. gingivalis and develop advanced periodontitis, the levels of normally benign, or commensal, bacteria increase in the affected periodontium. secondly, p. gingivalis is extremely difficult to detect at the site of the disease. these observations and last yearis finding on signaling crosstalk suggested that p. gingivalis might compromise the immune system, but the commensals infect the periodontium. in the current paper, that ' s exactly what they found. the scientists report that mice bred to produce immune cells without c5a receptors — meaning p. gingivalis can ' t co - opt their innate immunity — did not develop periodontitis after being inoculated with the bacterium. commensal levels also remained within the range typically seen in the subgingival space. in healthy mice kept under conventional laboratory conditions, the opposite was true when inoculated with p. gingivalis. the mice developed active periodontitis and its characteristic damage of the periodontium. they also had increased commensal levels and hardly detectable p. gingivalis. " in contrast, mice bred to be germ - free were resistant to periodontitis after they were colonized by p. gingivalis, " noted michael curtis, ph. d., a co - lead author on the study and a scientist at queen mary university in london. " this was especially telling because these mice lacked the normal


were colonized by p. gingivalis, " noted michael curtis, ph. d., a co - lead author on the study and a scientist at queen mary university in london. " this was especially telling because these mice lacked the normal commensal bacteria in their mouths. in other words, in these sterile animals, p. gingivalis had no bacterial accomplices capable of causing periodontitis. " " there is one key word that explains everything : homeostasis, " said richard darveau, m. s., ph. d., a scientist at the university of washington in seattle and another co - lead author on the paper. " periodontal health is a matter of maintaining homeostasis, or equilibrium, among the bacterial inhabitants of the subgingival space and innate immunity cells. p. gingivalis is a master at disrupting homeostasis. although this bacterium certainly is not the only cause of periodontitis, it stands out as a major culprit. " the scientists say their findings have encouraging therapeutic implications, in part because the microbial conditions in mice likely will be comparable in humans. they point to studies in monkeys that indicate the comparability. they also note their findings provide a molecular target with tremendous specificity. " to counteract p. gingivalis and the negative outcomes that it orchestrates in patients, we will need most likely to target one of the signaling receptors, " said john lambris, ph. d., an author on the paper and the dr. ralph and sallie weaver professor of research medicine at the university of pennsylvania. " p. gingivalis needs to manipulate both to work its tricks. " the national institute of dental and craniofacial research ( nidcr ) is the nationis leading funder of research on oral, dental, and craniofacial health. about the national institutes of health ( nih ) : nih, the nation ' s medical research agency, includes 27 institutes and centers and is a component of the u. s. department of health and human services. nih is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. for more information about nih and its programs, visit http : / / www. nih. gov. nih... turning discovery into health ®


advances in adhesive technology for joint replacements - 1 narrator : this is nih health matters, i ’ m joe balintfy. nearly 17 percent of artificial hip or knee replacements have to be redone early. dr. lyndon joseph at the nih says this can be even more traumatic for patients, and more complicated for doctors. joseph : because they have to take out the implant, give you a big dose of antibiotics and painkillers and so you ’ re basically laid up in a hospital for an extended period of time. narrator : now engineers are developing a coating for implants to help replacements last longer. the coating causes the patients to produce new bone around the implant, securing it in place. for details, visit www. nia. nih. gov. health matters is produced by the national institutes of health, part of the u. s. department of health and human services. about nih radio nih radio offers free audio news programs from the national institutes of health, your reliable source for health information. all nih radio content is in the public domain and can be used without charge or restriction provided that it is not used to misrepresent our agency nor used to suggest we endorse any private organization, product, or service. nih radio is a service of the office of communications & public liaison.


debate among industry and environmental groups on hydraulic fracturing in new jersey is heating up, as a bill to ban the practice remains on gov. chris christie ’ s desk after he signed a flurry of legislation earlier this week. “ new jersey has one of the highest concentrations of natural gas in the united states, and it ’ s really had a tremendous growth that many industry experts thought was impossible, ” said jim benton, executive director of the new jersey petroleum council. “ what we really need is the cheaper energy prices that can come from this practice, because you can ’ t have a successful economic recovery without solid energy growth and competitive energy costs. ” environmental groups have argued wastewater from fracking threatens the environment and public health, since the state ’ s treatment plants are not equipped to process the contaminants it contains before releasing it into waterways. “ radioactivity in wastewater from at least 15 wells was thousands of times higher than the epa standard … and this waste is already coming into new jersey, posing a serious public health threat, ” said jeff tittel, director of the state chapter of the sierra club. “ there could be accidental spills as fracking wastewater is being trucked to treatment plants with impacts to local communities, water bodies and groundwater. ” but benton said the coalition ’ s arguments are “ based on a hypothetical fear and unsubstantiated types of claims, ” since “ the treatment facilities have stated they can claim this water when it comes to them … and recycle it right there on site. ” “ businesses are already operating under regulated parameters … because federal law doesn ’ t permit the type of activity everyone ’ s arguing against, ” benton said. “ regulation can easily help the facilities meet the appropriate environmental standards to protect our water and help companies develop this energy to meet our energy needs. ” but with the state still under a one - year ban of the practice, which was supported by christie, benton noted “ at this point, the interest in properly regulating this hasn ’ t materialized. ” still, the state department of environmental protection recently revised its guidelines on fracking wastewater, though tittel noted there are no federal regulations outlining treatment standards, and “ under the ( dep ) waiver rule, any regulations the dep does devise would be waived for gas companies and treatment facilities. ” “ accepting fracking waste takes away sewer capacity from new jersey businesses, hurting our economic growth, ” tittel said in a statement. “ the treatment plants would make more money taking in the


courtesy of the john d. & catherine t. macarthur foundation over the past four decades, benoit rolland has made more than 1, 400 bows for violins, violas and cellos. over the past four decades, benoit rolland has made more than 1, 400 bows for violins, violas and cellos. courtesy of the john d. & catherine t. macarthur foundation among the 23 recipients of the macarthur " genius " grants this past week : an economist, a mathematician, a photographer, a neuroscientist, and a boston - based stringed instrument bow maker. benoit rolland acknowledges that the violin reigns supreme as the star of the strings, capable of fetching millions of dollars at auction. but what about the bow? " a violin with no bow is not a violin, that ' s clear, " says rolland. " a lot of people, even some instrumentalists, in our younger years we believe that the violin is of paramount importance and the bow is just a tool, " says elita kang, assistant concert master of the boston symphony orchestra. " but the bow is just as important as the violin because that is our breath. that ' s how we draw the sound out of the instrument, so without a fine bow that ' s responsive and flexible and finely made, we can ' t express ourselves fully. " kang says a significant number of bso musicians use bows made by rolland. so have some of the most famous string players of all time : yehudi menuhin, stephane grapelli, mstislav rostropovich. over the past four decades, rolland has made more than 1, 400 bows for violins, violas and cellos. " i could say the bow is extremely important for a musician because it has to convey the personality, the musicality, the feelings, the emotions of the musician through it, and it ' s something that has to behave like a muscle, " says rolland. that understanding is only part of why rolland won a macarthur genius grant. he ' s revered for his knowledge of traditional bow - making skills but also for his innovations. he pioneered the first concert - grade graphite bow. and his most recent invention is an updated " frog " — the piece on the bow ' s end used to adjust tension. " it ' s much more stable, " rolland says, " so it ' s easier to play, more responsive, the sound is fuller — most of the time, not all of the time. so it ' s


used to adjust tension. " it ' s much more stable, " rolland says, " so it ' s easier to play, more responsive, the sound is fuller — most of the time, not all of the time. so it ' s an improvement i think is interesting. and this frog is adjustable on any existing stick. " rolland ' s journey as a bow maker began in paris, where his grandmother was a famous concert pianist. rolland had perfect pitch, and when he was 9 he fell in love with the violin. he graduated from the conservatories of paris and versailles, and was on track to become a professional musician — but then he saw a spectacular bow. " this bow was so beautiful, fitted with gold, 18 karats, and magnificent mother of pearl and magnificent wood. it was like a jewel, " says rolland. " so at this very moment, i understood this was what i want to do. " he went on to study the traditional french method of bow making and has been doing this ever since. rolland says the most important variables are the musicians themselves. he interviews them, watches them perform and listens closely to their music. miriam fried has three of his bows and is one of the many musicians who wrote letters to the macarthur foundation endorsing rolland ' s nomination. she ' s a violinist and teacher at the new england conservatory. " what i ' m really excited about is the fact that benoit rolland just was one of the recipients of the macarthur grant, which i think is fabulous, " says fried. his years of bow making have stiffened his fingers, so it ' s difficult for him to play nowadays. but rolland says he still gets pleasure watching and listening to other musicians using his bows. " because i see this person playing so intimate things — the music — with something i brought in his hands, so it ' s marvelous, " says rolland. and he says the macarthur stipend of $ 500, 000 will enable him not only to improve his centuries - old art, but also to pursue even more innovations. note : npr is among the organizations that the john d. and catherine t. macarthur foundation supports.