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can be placed into 3 generalized domains based on their molecular structure. These three domains are organometallic photosensitizers, organic photosensitizers, and nanomaterial photosensitizers. === Organometallic === Organometallic photosensitizers contain a metal atom chelated to at least one organic ligand. The phot...	{ "page_id": 2825553, "title": "Photosensitizer" }
benzophenones, methylene blue, rose Bengal, flavins, pterins and others. === Nanomaterials === A wide variety of nanomaterials function as photosensitizers. Monatomic gaseous mercury (considered as the smallest possible cluster compound) is a photosensitizer catalyzing radical dehydrogenation. ==== Quantum dots ==== Co...	{ "page_id": 2825553, "title": "Photosensitizer" }
excited singlet oxygen. The resulting excited oxygen species then selectively degrades the tumor or cancerous mass. In February 2019, medical scientists announced that iridium attached to albumin, creating a photosensitized molecule, can penetrate cancer cells and, after being irradiated with light (a process called ph...	{ "page_id": 2825553, "title": "Photosensitizer" }
through an externally applied light source. These photosensitizers used in redox chemistry may be organic, organometallic, or nanomaterials depending on the physical and spectral properties required for the reaction. == Biological effects of photosensitizers == Photosensitizers that are readily incorporated into the ex...	{ "page_id": 2825553, "title": "Photosensitizer" }
Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel is also sometimes referred to as texture. It is used in many areas related to ...	{ "page_id": 3874132, "title": "Mouthfeel" }
tongue and palate Heaviness: The weight of product perceived when first placed on tongue Juiciness Moisture absorption: The amount of saliva absorbed by product Moisture release: The amount of wetness/juiciness released from sample Mouthcoating: The type and degree of coating in the mouth after mastication (for example...	{ "page_id": 3874132, "title": "Mouthfeel" }
Lamina is a general anatomical term meaning "plate" or "layer". It is used in both gross anatomy and microscopic anatomy to describe structures. Some examples include: The laminae of the thyroid cartilage: two leaf-like plates of cartilage that make up the walls of the structure. The vertebral laminae: plates of bone t...	{ "page_id": 2104661, "title": "Lamina (anatomy)" }
Genetic ecology is the study of the stability and expression of varying genetic material within abiotic mediums. Typically, genetic data is not thought of outside of any organism save for criminal forensics. However, genetic material has the ability to be taken up by various organisms that exist within an abiotic mediu...	{ "page_id": 55319895, "title": "Genetic ecology" }
they need to survive in an environment. This can help many bacterial species survive within an environment. A similar event has the ability to happen between plants and bacteria. For example, Agrobacterium tumefaciens has the ability to introduce genes into plants to cause the development of Gall disease. This occurs t...	{ "page_id": 55319895, "title": "Genetic ecology" }
Tris(dimethylamino)aluminium dimer, formally bis(μ-dimethylamino)tetrakis(dimethylamino)dialuminium, is an amide complex of aluminium. This compound may be used as a precursor to other aluminium complexes. Commercially available, this compound may be prepared from lithium dimethylamide and aluminium trichloride. == Ref...	{ "page_id": 32513367, "title": "Tris(dimethylamino)aluminium dimer" }
The polar surface area (PSA) or topological polar surface area (TPSA) of a molecule is defined as the surface sum over all polar atoms or molecules, primarily oxygen and nitrogen, also including their attached hydrogen atoms. PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to ...	{ "page_id": 5578072, "title": "Polar surface area" }
== References == == Literature == Pajouhesh, Hassan; Lenz, George R (2005). "Medicinal chemical properties of successful central nervous system drugs". NeuroRx. 2 (4): 541–553. doi:10.1602/neurorx.2.4.541. PMC 1201314. PMID 16489364. Clark, David E (1999). "Rapid calculation of polar molecular surface area and its appl...	{ "page_id": 5578072, "title": "Polar surface area" }
Theoretical astronomy is the use of analytical and computational models based on principles from physics and chemistry to describe and explain astronomical objects and astronomical phenomena. Theorists in astronomy endeavor to create theoretical models and from the results predict observational consequences of those mo...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
elucidation of astronomical phenomena, and astronomy has helped in the elucidation of physical phenomena: discovery of the law of gravitation came from the information provided by the motion of the Moon and the planets, viability of nuclear fusion as demonstrated in the Sun and stars and yet to be reproduced on earth i...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
symmetry-forbidden reactions cannot occur except on the longest of timescales. For this reason, molecules and molecular ions which are unstable on earth can be highly abundant in space, for example the H3+ ion. Astrochemistry overlaps with astrophysics and nuclear physics in characterizing the nuclear reactions which o...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
new data. Consistent with the general scientific approach, in the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model. == Topics of theoretical astronomy...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
black holes === A general form of the first law of thermodynamics for stationary black holes can be derived from the microcanonical functional integral for the gravitational field. The boundary data the gravitational field as described with a microcanonical system in a spatially finite region and the density of states ...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
and nitrogen-15 (15N), which is indicative of their retention of an interstellar heritage. === Chemistry in cometary comae === The chemical composition of comets should reflect both the conditions in the outer solar nebula some 4.5 × 109 ayr, and the nature of the natal interstellar cloud from which the Solar System wa...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
the supernova radioactivity: the radiogenesis of 44Ca from 44Ti decay after carbon condensation establishes their supernova source, their opacity suffices to shift emission lines blueward after 500 d and emits significant infrared luminosity, parallel kinetic rates determine trace isotopes in meteoritic supernova graph...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
the succession of brightness and darkness => the day (and night). High precision appears problematic: ambiguities arise in the exact definition of a rotation or revolution, some astronomical processes are uneven and irregular, such as the noncommensurability of year, month, and day, there are a multitude of time scales...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
based on what had become the standard SI second, which in turn had been derived from the measured second of ET. During the period 1991–2006, the TDB and TDT time scales were both redefined and replaced, owing to difficulties or inconsistencies in their original definitions. The current fundamental relativistic time sca...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
{\frac {R^{3}}{2GM}}}\sim 1/{\sqrt {G\rho }}} where R is the radius of the star, G is the gravitational constant, M is the mass of the star, ρ the star gas density (assumed constant here) and v is the escape velocity. As an example, the Sun dynamical time scale is approximately 1133 seconds. Note that the actual time i...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
or celestial navigation is disappearing from the surface and beneath or above the surface of the Earth. Geodetic astronomy is the application of astronomical methods into networks and technical projects of geodesy for apparent places of stars, and their proper motions precise astronomical navigation astro-geodetic geoi...	{ "page_id": 2039133, "title": "Theoretical astronomy" }
References == == External links == Introduction to Cataclysmic Variables (CVs) L. Sidoli, 2008 Transient outburst mechanisms Commentary on "The Compendium of Plain Astronomy" is a manuscript from 1665 about theoretical astronomy	{ "page_id": 2039133, "title": "Theoretical astronomy" }
An acidophobe is an organism that is intolerant of acidic environments. The terms acidophobia, acidophoby and acidophobic are also used. The term acidophobe is variously applied to plants, bacteria, protozoa, animals, chemical compounds, etc. The antonymous term is acidophile. Plants are known to be well-defined with r...	{ "page_id": 4136287, "title": "Acidophobe" }
Brown clustering is a hard hierarchical agglomerative clustering problem based on distributional information proposed by Peter Brown, William A. Brown, Vincent Della Pietra, Peter V. de Souza, Jennifer Lai, and Robert Mercer. The method, which is based on bigram language models, is typically applied to text, grouping w...	{ "page_id": 42016100, "title": "Brown clustering" }
least loss in global mutual information. As a result, the output can be thought of not only as a binary tree but perhaps more helpfully as a sequence of merges, terminating with one big class of all words. This model has the same general form as a hidden Markov model, reduced to bigram probabilities in Brown's solution...	{ "page_id": 42016100, "title": "Brown clustering" }
as new features for the tagger. == Variations == Brown clustering has also been explored using trigrams. Brown clustering as proposed generates a fixed number of output classes. It is important to choose the correct number of classes, which is task-dependent. The cluster memberships of words resulting from Brown cluste...	{ "page_id": 42016100, "title": "Brown clustering" }
Allelic exclusion is a process by which only one allele of a gene is expressed while the other allele is silenced. This phenomenon is most notable for playing a role in the development of B lymphocytes, where allelic exclusion allows for each mature B lymphocyte to express only one type of immunoglobulin. This subseque...	{ "page_id": 6561124, "title": "Allelic exclusion" }
=== ==== Stochastic ==== In the stochastic model, while the Ig rearrangement is proposed to be very efficient, the probability of functional allelic rearrangement is assumed to be very low as compared to the probability of non-functional rearrangement. As a result, successful recombination of more than one functional I...	{ "page_id": 6561124, "title": "Allelic exclusion" }
step is a random and non-specific process that occurs one allele at a time where segments V, (D) and J are rearranged to encode the variable region, resulting in a fraction of functional genes with a productive V(D)J region. Allelic exclusion is then enforced via feedback inhibition where the functional Ig gene inhibit...	{ "page_id": 6561124, "title": "Allelic exclusion" }
to 5-fold increase partly due to Gata3 transcriptional activation from monoallelic to biallelic primarily resulted in both alleles of TCR𝛽 recombining. Intracellular GATA3 expression can divide wild-type immature thymocyte cell populations. Although cells regardless of GATA3 expression level yielded functional TCR𝛽 s...	{ "page_id": 6561124, "title": "Allelic exclusion" }
Smart ligands are affinity ligands selected with pre-defined equilibrium ( K d {\displaystyle K_{d}} ), kinetic ( k o f f {\displaystyle k_{off}} , k o n {\displaystyle k_{on}} ) and thermodynamic (ΔH, ΔS) parameters of biomolecular interaction. Ligands with desired parameters can be selected from large combinatorial l...	{ "page_id": 12918117, "title": "Smart ligand" }
Traditional Phenological Knowledge can be seen as a "subset of Indigenous Knowledge". Traditional Phenological Knowledge (TPK) is the knowledge based on traditional observations made by Indigenous Peoples that predict seasonal changes of nature and their immediate environment. This can be useful for the management of n...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
to the essence of TPK. == Phenology == Phenology observes the timing of seasonality of biological and weather events. Plant cycles, animal behaviour, weather patterns and climate change cycle through seasonality i.e.Flowering. As Swartz defines; "Phenology is the study of recurring plant, fungi and animal life cycle st...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
from group to group, however, the many Indigenous groups share similarities regarding the innate knowledge of seasonal timings and landscape ecological practices. The perception of time is unlike that of the Western world. For instance, the rainy season in some Indigenous communities may signal spring and/ or fall and ...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
and aid full-light vegetation to grow in these areas i.e. Oak and Huckleberries. Hence, Traditional Knowledge and TPK can help with food security, food for wildlife. === Western applications === TPK and TEK are seen as sustainable practices to help fight against climate change and are starting to be recognised as a too...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
than Western-based communities.The Western world is impacted mostly economically, financially and ecologically, whereas Indigenous communities have certain practices and traditions that are directly tied to the land. The change in climate might affect and threaten their livelihood and their relationship to the land. In...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
and earlier ripening. This is seen in cloud berries, blueberries and crowberries. == Barriers and challenges == Some of the barriers of TPK would be that some institutions do not recognise TPK as a scientific way of practice due to Western ways of teaching. This is can be due to priority of importance of the institutio...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
Eastern Uganda, the Iteso people of Teso practice TPK in terms of agriculture and pasture. This region has a hot and humid climate. There is a strong agricultural practice in the region of Teso. The main crops cultivated are cereal such as millet, corn, cassava and cotton. The main animals for livestock are pigs, cattl...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
of life. Herders have a distinct way of understanding plants of the landscape. Mongolia has a mix of extreme climates which temperatures could reach 40 degrees Celsius in warmer months, to below 30 degrees in colder months. Mongolia is also desertic, mountainous, contains grasslands. It is a considerably dry climate. T...	{ "page_id": 73276775, "title": "Traditional Phenological Knowledge" }
Patrick H. O'Farrell is a molecular biologist who made crucial contribution to the development of 2-dimensional protein electrophoresis and Drosophila genetics. He is now a professor of Biochemistry at the University of California, San Francisco (UCSF) and has a h-index of 67. == Education == O'Farrell received his bac...	{ "page_id": 21241192, "title": "Patrick H. O'Farrell" }
DNA laddering is a feature that can be observed when DNA fragments, resulting from Apoptosis DNA fragmentation are visualized after separation by gel electrophoresis the first described in 1980 by Andrew Wyllie at the University Edinburgh medical school DNA fragments can also be detected in cells that underwent necrosi...	{ "page_id": 4791660, "title": "DNA laddering" }
apoptosis, other assays are used along with DNA laddering such as TEM and TUNEL. With recent improvements to DNA laddering, DNA laddering has become a more reliable, and reasonable technique to use when detecting apoptosis. It is also important to note that DNA laddering occurs differently depending on the type of cell...	{ "page_id": 4791660, "title": "DNA laddering" }
Centripetal force (from Latin centrum, "center" and petere, "to seek") is the force that makes a body follow a curved path. The direction of the centripetal force is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton coined the term...	{ "page_id": 7534, "title": "Centripetal force" }
{\displaystyle F_{c}=ma_{c}=m{\frac {v^{2}}{r}}} and is, like centripetal acceleration, directed toward the center of curvature of the object's trajectory. === Derivation === The centripetal acceleration can be inferred from the diagram of the velocity vectors at two instances. In the case of uniform circular motion th...	{ "page_id": 7534, "title": "Centripetal force" }
the object about the center of the circle, related to the tangential velocity by the formula v = ω r {\displaystyle v=\omega r} so that F c = m r ω 2 . {\displaystyle F_{c}=mr\omega ^{2}\,.} Expressed using the orbital period T for one revolution of the circle, ω = 2 π T {\displaystyle \omega ={\frac {2\pi }{T}}} the e...	{ "page_id": 7534, "title": "Centripetal force" }
even though in the case of eccentric orbits, the gravitational force is directed towards the focus, and not towards the instantaneous center of curvature. Another example of centripetal force arises in the helix that is traced out when a charged particle moves in a uniform magnetic field in the absence of other externa...	{ "page_id": 7534, "title": "Centripetal force" }
t ) x ^ + r sin ⁡ ( ω t ) y ^ , {\displaystyle {\textbf {r}}=r\cos(\omega t){\hat {\mathbf {x} }}+r\sin(\omega t){\hat {\mathbf {y} }},} v = r ˙ = − r ω sin ⁡ ( ω t ) x ^ + r ω cos ⁡ ( ω t ) y ^ , {\displaystyle {\textbf {v}}={\dot {\textbf {r}}}=-r\omega \sin(\omega t){\hat {\mathbf {x} }}+r\omega \cos(\omega t){\hat ...	{ "page_id": 7534, "title": "Centripetal force" }
t ) d t , {\displaystyle \mathrm {d} {\boldsymbol {\ell }}=\mathbf {\Omega } \times \mathbf {r} (t)\mathrm {d} t\ ,} which, by properties of the vector cross product, has magnitude rdθ and is in the direction tangent to the circular path. Consequently, d r d t = lim Δ t → 0 r ( t + Δ t ) − r ( t ) Δ t = d ℓ d t . {\dis...	{ "page_id": 7534, "title": "Centripetal force" }
\| 2 r ( t ) . {\displaystyle \mathbf {a} =-{\|\mathbf {\Omega \|} }^{2}\mathbf {r} (t)\ .} In words, the acceleration is pointing directly opposite to the radial displacement r at all times, and has a magnitude: \| a \| = \| r ( t ) \| ( d θ d t ) 2 = r ω 2 {\displaystyle \|\mathbf {a} \|=\|\mathbf {r} (t)\|\left({\frac {\mathrm...	{ "page_id": 7534, "title": "Centripetal force" }
mass of the ball and g is the gravitational acceleration; the second is the upward normal force exerted by the road at a right angle to the road surface man. The centripetal force demanded by the curved motion is also shown above. This centripetal force is not a third force applied to the ball, but rather must be provi...	{ "page_id": 7534, "title": "Centripetal force" }
. {\displaystyle \|\mathbf {F} _{\mathrm {c} }\|=m\|\mathbf {a} _{\mathrm {c} }\|={\frac {m\|\mathbf {v} \|^{2}}{r}}\,.} Consequently, the ball is in a stable path when the angle of the road is set to satisfy the condition: m \| g \| tan ⁡ θ = m \| v \| 2 r , {\displaystyle m\|\mathbf {g} \|\tan \theta ={\frac {m\|\mathbf {v} \|^{2}...	{ "page_id": 7534, "title": "Centripetal force" }
R·ur, where R is a constant (the radius of the circle) and ur is the unit vector pointing from the origin to the point mass. The direction of ur is described by θ, the angle between the x-axis and the unit vector, measured counterclockwise from the x-axis. The other unit vector for polar coordinates, uθ is perpendicula...	{ "page_id": 7534, "title": "Centripetal force" }
{\hat {\mathbf {j} }}\right)\\&=r{\frac {d\theta }{dt}}\mathbf {u} _{\theta }\\&=\omega r\mathbf {u} _{\theta }\end{aligned}}} where ω is the angular velocity dθ/dt. This result for the velocity matches expectations that the velocity should be directed tangentially to the circle, and that the magnitude of the velocity ...	{ "page_id": 7534, "title": "Centripetal force" }
within a plane, as shown next. Polar coordinates in the plane employ a radial unit vector uρ and an angular unit vector uθ, as shown above. A particle at position r is described by: r = ρ u ρ , {\displaystyle \mathbf {r} =\rho \mathbf {u} _{\rho }\ ,} where the notation ρ is used to describe the distance of the path fr...	{ "page_id": 7534, "title": "Centripetal force" }
Therefore, the change in uρ is d u ρ = u θ d θ , {\displaystyle \mathrm {d} \mathbf {u} _{\rho }=\mathbf {u} _{\theta }\mathrm {d} \theta \,,} or d u ρ d t = u θ d θ d t . {\displaystyle {\frac {\mathrm {d} \mathbf {u} _{\rho }}{\mathrm {d} t}}=\mathbf {u} _{\theta }{\frac {\mathrm {d} \theta }{\mathrm {d} t}}\,.} In a...	{ "page_id": 7534, "title": "Centripetal force" }
d θ d t + ρ d u θ d t d θ d t + ρ u θ d 2 θ d t 2 . {\displaystyle \mathbf {a} ={\frac {\mathrm {d} ^{2}\rho }{\mathrm {d} t^{2}}}\mathbf {u} _{\rho }+{\frac {\mathrm {d} \rho }{\mathrm {d} t}}{\frac {\mathrm {d} \mathbf {u} _{\rho }}{\mathrm {d} t}}+{\frac {\mathrm {d} \rho }{\mathrm {d} t}}\mathbf {u} _{\theta }{\fra...	{ "page_id": 7534, "title": "Centripetal force" }
t}}{\frac {\mathrm {d} \theta }{\mathrm {d} t}}+\rho {\frac {\mathrm {d} ^{2}\theta }{\mathrm {d} t^{2}}}\right]\\&=\mathbf {u} _{\rho }\left[{\frac {\mathrm {d} v_{\rho }}{\mathrm {d} t}}-{\frac {v_{\theta }^{2}}{\rho }}\right]+\mathbf {u} _{\theta }\left[{\frac {2}{\rho }}v_{\rho }v_{\theta }+\rho {\frac {\mathrm {d}...	{ "page_id": 7534, "title": "Centripetal force" }
of coordinates that travel with the particle, and have orientation determined by the path of the particle. Unit vectors are formed as shown in the image at right, both tangential and normal to the path. This coordinate system sometimes is referred to as intrinsic or path coordinates or nt-coordinates, for normal-tangen...	{ "page_id": 7534, "title": "Centripetal force" }
The local value of the angular rate of rotation then is given by: ω ( s ) = d θ d t = d θ d s d s d t = 1 ρ ( s ) d s d t = v ( s ) ρ ( s ) , {\displaystyle \omega (s)={\frac {\mathrm {d} \theta }{\mathrm {d} t}}={\frac {\mathrm {d} \theta }{\mathrm {d} s}}{\frac {\mathrm {d} s}{\mathrm {d} t}}={\frac {1}{\rho (s)}}\ {...	{ "page_id": 7534, "title": "Centripetal force" }
{\mathrm {d} v}{\mathrm {d} t}}\mathbf {u} _{\mathrm {t} }(s)-{\frac {v^{2}}{\rho }}\mathbf {u} _{\mathrm {n} }(s)\ ;} with the tangential acceleration d v d t = d v d s d s d t = d v d s v . {\displaystyle {\frac {\mathrm {\mathrm {d} } v}{\mathrm {\mathrm {d} } t}}={\frac {\mathrm {d} v}{\mathrm {d} s}}\ {\frac {\mat...	{ "page_id": 7534, "title": "Centripetal force" }
are introduced to denote derivatives with respect to s. The magnitude of this displacement is ds, showing that: [ x ′ ( s ) 2 + y ′ ( s ) 2 ] = 1 . {\displaystyle \left[x'(s)^{2}+y'(s)^{2}\right]=1\ .} (Eq. 1) This displacement is necessarily a tangent to the curve at s, showing that the unit vector tangent to the curv...	{ "page_id": 7534, "title": "Centripetal force" }
1 ρ cos ⁡ θ = 1 ρ x ′ ( s ) . {\displaystyle {\frac {\mathrm {d} \sin \theta }{\mathrm {d} s}}=\cos \theta {\frac {\mathrm {d} \theta }{\mathrm {d} s}}={\frac {1}{\rho }}\cos \theta \ ={\frac {1}{\rho }}x'(s)\ .} Now: d sin ⁡ θ d s = d d s y ′ ( s ) x ′ ( s ) 2 + y ′ ( s ) 2 = y ″ ( s ) x ′ ( s ) 2 − y ′ ( s ) x ′ ( s ...	{ "page_id": 7534, "title": "Centripetal force" }
] = ( d 2 s d t 2 ) u t ( s ) + ( d s d t ) 2 ( x ″ ( s ) , y ″ ( s ) ) = ( d 2 s d t 2 ) u t ( s ) − ( d s d t ) 2 1 ρ u n ( s ) {\displaystyle {\begin{aligned}\mathbf {a} (s)&={\frac {\mathrm {d} }{\mathrm {d} t}}\mathbf {v} (s)={\frac {\mathrm {d} }{\mathrm {d} t}}\left[{\frac {\mathrm {d} s}{\mathrm {d} t}}\left(x'...	{ "page_id": 7534, "title": "Centripetal force" }
y be given as: x = α cos ⁡ s α ; y = α sin ⁡ s α . {\displaystyle x=\alpha \cos {\frac {s}{\alpha }}\ ;\ y=\alpha \sin {\frac {s}{\alpha }}\ .} Then: x 2 + y 2 = α 2 , {\displaystyle x^{2}+y^{2}=\alpha ^{2}\ ,} which can be recognized as a circular path around the origin with radius α. The position s = 0 corresponds to...	{ "page_id": 7534, "title": "Centripetal force" }
}(s)=\left[\cos {\frac {s}{\alpha }}\ ,\ \sin {\frac {s}{\alpha }}\right]\ ,} which serve to show that s = 0 is located at position [ρ, 0] and s = ρπ/2 at [0, ρ], which agrees with the original expressions for x and y. In other words, s is measured counterclockwise around the circle from 3 o'clock. Also, the derivative...	{ "page_id": 7534, "title": "Centripetal force" }
u n ( s ) d s d t {\displaystyle \mathbf {a} ={\frac {\mathrm {d} v}{\mathrm {d} t}}\mathbf {u} _{\mathrm {t} }(s)+v{\frac {\mathrm {d} }{\mathrm {d} t}}\mathbf {u} _{\mathrm {t} }(s)={\frac {\mathrm {d} v}{\mathrm {d} t}}\mathbf {u} _{\mathrm {t} }(s)-v{\frac {1}{\alpha }}\mathbf {u} _{\mathrm {n} }(s){\frac {\mathrm ...	{ "page_id": 7534, "title": "Centripetal force" }
The Pfitzinger reaction (also known as the Pfitzinger-Borsche reaction) is the chemical reaction of isatin with base and a carbonyl compound to yield substituted quinoline-4-carboxylic acids. Several reviews have been published. == Reaction mechanism == The reaction of isatin with a base such as potassium hydroxide hyd...	{ "page_id": 13507959, "title": "Pfitzinger reaction" }
Yeshayahu Leibowitz (Hebrew: ישעיהו ליבוביץ‎; 29 January 1903 – 18 August 1994) was an Israeli Orthodox Jewish public intellectual and polymath. He was a professor of biochemistry, organic chemistry, and neurophysiology at the Hebrew University of Jerusalem, as well as a prolific writer on Jewish thought and western ph...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
of the Hebrew University of Jerusalem in 1936. He became a professor of biochemistry in 1941, and was promoted to the position of senior professor of organic chemistry and neurology in 1952. He taught at the Hebrew University for nearly six decades, lecturing in biochemistry, neurophysiology, philosophy, and the histor...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
before God rather than their position before their fellow man. The essence of Leibowitz's religious outlook is that a person's faith is his commitment to obey God, meaning God's commandments, and this has nothing to do with a person's image of God. This must be so because Leibowitz thought that God cannot be described,...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
of any actual historical information in the Torah would be merely coincidental, and that all descriptions of God intervening in nature and history were not to be seen as factual but rather interpreted in terms of the messages they carry, as his ideas of God's transcendence denied that there could be any such contact be...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
as well as Kabbalah, seeing them as encouraging people to not perform mitzvot for their own sake but ascribing a stated purpose to them. Reform Judaism teaches the concept of "ethical monotheism" and Judaism as having the mission of being a "light unto the nations" and Kabbalah seeks universal redemption through the pe...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
Leibowitz believed that despite the ban on homosexual relations in Judaism, homosexuals should do their best to remain observant Jews. Leibowitz was also an advocate of increased gender egalitarianism in Jewish practice, writing that: "The halakhic decisions in Judaism barring women from public office tell us more abou...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
would run the future Jewish state. He proposed a form of democratic halakhic Judaism. In the 1949 Knesset election, Leibowitz headed the United List of Religious Workers, which failed to win a seat. Following Israeli independence, Leibowitz moved away from religious Zionism. He was disappointed with the way the religio...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
as deceitful and expansionist. He wrote that although Ben-Gurion publicly stated in the Knesset that he opposed a preemptive war against Egypt, he secretly worked to plan one and later declared an expansion of Israel’s borders, referring to it as “The Third Kingdom of Israel,” extending as far as the island of Tiran. M...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
which has been until now a people's army, would, as a result of being transformed into an army of occupation, degenerate, and its commanders, who will have become military governors, resemble their colleagues in other nations. In an interview in Haaretz newspaper, Carlo Strenger, who knew Leibowitz personally, stated: ...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
the occupied territories. == Awards and recognition == In 1993, Leibowitz was selected for the Israel Prize for Lifetime Achievement. Before the award ceremony, Leibowitz was invited to speak to the Israel Council for Israeli–Palestinian Peace, where his controversial remarks calling upon Israeli soldiers to refuse ord...	{ "page_id": 1056121, "title": "Yeshayahu Leibowitz" }
The deep biosphere is the part of the biosphere that resides below the first few meters of the ocean's surface. It extends 10 km (6.2 mi) below the continental surface and 21 km (13 mi) below the sea surface, at temperatures that may reach beyond 120 °C (248 °F) which is comparable to the maximum temperature where a me...	{ "page_id": 61218171, "title": "Deep biosphere" }
The deep biosphere is an ecosystem of organisms and their living space in the deep subsurface. For the seafloor, an operational definition of deep subsurface is the region that is not bioturbated by animals; this is generally about a meter or more below the surface. On continents, it is below a few meters, not includin...	{ "page_id": 61218171, "title": "Deep biosphere" }
late 1930s to the 1950s. Although the coring depth was limited, microbes were found wherever the sediments were sampled. With increasing depth, aerobes gave way to anaerobes. Most biologists dismissed the subsurface microbes as contamination, especially after the submersible Alvin sank in 1968 and the scientists escape...	{ "page_id": 61218171, "title": "Deep biosphere" }
and it took them four years to publish their results. In 1992, Thomas Gold published a paper titled "The Deep, Hot Biosphere" suggesting that microbial life was widespread throughout the subsurface, existing in pore spaces between grains of rocks. He also published a book similarly titled The Deep Hot Biosphere. Accord...	{ "page_id": 61218171, "title": "Deep biosphere" }
the number of holes that can be drilled. Microbiologists have made use of scientific drilling programs: the Ocean Drilling Program (ODP), which used the JOIDES Resolution drilling platform, and the Integrated Ocean Drilling Program (IODP), which used the Japanese ship Chikyū. Deep underground mines, for example South A...	{ "page_id": 61218171, "title": "Deep biosphere" }
of microbes on properties of geological materials are remotely probed using electrical signals. Microbes can be tagged using a stable isotope, such as carbon-13, and then re-injected in the ground to see where they go. A "push-pull" method involves injection of a fluid into an aquifer and extraction of a mixture of inj...	{ "page_id": 61218171, "title": "Deep biosphere" }
in ore bodies, subduction, methane clathrate formation and decomposition, permafrost thawing, infrared radiation and seismic activity. Humans also create new habitats for life, particularly through remediation of contaminants in the subsurface. === Energy sources === Life requires enough energy to construct adenosine t...	{ "page_id": 61218171, "title": "Deep biosphere" }
make it scarce. It is particularly rich in hydrothermal fluids where it is produced by serpentinization. Multiple species can combine fermentation with methanogenesis and iron oxidation with hydrogen consumption. Methane is mostly found in marine sediments, in gaseous form (dissolved or free) or in methane hydrates. Ab...	{ "page_id": 61218171, "title": "Deep biosphere" }
sediments, which accumulate mainly in continental margins. Organic carbon is mainly produced at the surface of the oceans with photosynthesis or washed into oceans with terrestrial sediments. Only a small fraction is produced in the deep seas with chemosynthesis. When organic carbon sinks from the surface of the ocean ...	{ "page_id": 61218171, "title": "Deep biosphere" }
pressures less than 50 MPa. As of 2019, most sampling of organisms from the deep ocean and subsurface undergo decompression when they are removed to the surface. This can harm the cells in a variety of ways, and experiments at surface pressures produce an inaccurate picture of microbial activity in the deep biosphere. ...	{ "page_id": 61218171, "title": "Deep biosphere" }
Although microorganisms have been detected at temperatures up to 118 °C in cored sediments, attempts to isolate the organisms have failed. There can also be depth intervals with less cells than the deeper part of the location. Reasons for such 'low- or no-cell intervals' are still unknown but may be related to the unde...	{ "page_id": 61218171, "title": "Deep biosphere" }
RNA (e.g., proofreading and synthesis). However, laboratory estimates of the energy needed are several orders of magnitude greater than the energy supply that appears to sustain life underground. It was thought, at first, that most underground cells are dormant. However, some extra energy is required to come out of dor...	{ "page_id": 61218171, "title": "Deep biosphere" }
sediments, the main bacterial phyla are "Candidatus Atribacteria" (formerly OP9 and JS1), Pseudomonadota, Chloroflexota, and Planctomycetota. Members of Archaea were first identified using metagenomic analysis, but some of them have since been cultured and acquired new names. The Deep Sea Archaeal Group (DSAG) became t...	{ "page_id": 61218171, "title": "Deep biosphere" }
space of the terrestrial land mass down to 5 km depth was filled with water, and if 1% of this volume were microbial biomass, it would be enough living matter to cover Earth's land surface with a 1.5 m thick layer. The estimated volume of the deep biosphere is 2–2.3 billion cubic kilometers, about twice the volume of t...	{ "page_id": 61218171, "title": "Deep biosphere" }
Below that, the anaerobic reduction of methane is facilitated by sulfate in the sulfate-methane transition zone (SMTZ). Once the sulfates are depleted, methane formation takes over. The depth of the chemical zones depends on the rate that organic matter is deposited. Where it is rapid, oxygen is taken up rapidly as org...	{ "page_id": 61218171, "title": "Deep biosphere" }
is a lot of organic material in the sediments, and all the oxygen is used up in its consumption. They have very stable temperature and pressure profiles. The population of microbes is orders of magnitude greater than in the abyssal plains. It includes strict anaerobes including members of the Chloroflexi phylum, "Ca. A...	{ "page_id": 61218171, "title": "Deep biosphere" }
living organisms. In the younger crust, there is a lot of iron and sulfur cycling. Sediment cover slows the cooling and reduces the flow of water. There is little evidence of microbe activity in older (more than 10 million year old) crust. Near subduction zones, volcanoes can form in island arcs and back-arc regions. T...	{ "page_id": 61218171, "title": "Deep biosphere" }
orders of magnitude. In the top one or two meters of soils, organisms depend on oxygen and are heterotrophs, depending on the breakdown of organic carbon for their nutrition, and their decline in density parallels that of the organic material. Below that, there is no correlation, although both cell density and organic ...	{ "page_id": 61218171, "title": "Deep biosphere" }
independent of photosynthesis. == Ecology == One species of bacteria, "Candidatus Desulforudis audaxviator", is the first known to comprise a complete ecosystem by itself. It was found 2.8 km (1.7 mi) below the surface in a gold mine near Johannesburg, South Africa. In alkaline water at a temperature of about 60 °C, wi...	{ "page_id": 61218171, "title": "Deep biosphere" }
sugar-fermenting Bacteroidetes produce propionate, among other compounds, and this is fermented by "Ca. Atribacteria" to produce hydrogen. In upper sediments, sulfate-reducing bacteria take up most of the hydrogen, while in lower sediments the sulfate is depleted and methanogens dominate. In the sulfate-methane transit...	{ "page_id": 61218171, "title": "Deep biosphere" }
Potassium nitrate is an oxidizer so storing it near fire hazards or reducing agents should be avoided to minimise risk in case of a fire. == Product Identification == Synonyms: Saltpetre; Niter/Nitre; Nitric acid potassium salt; Salt Peter CAS No.: 7757-79-1 Molecular Weight: 101.1 Chemical Formula: KNO3 == Hazards Ide...	{ "page_id": 7282047, "title": "Potassium nitrate (data page)" }

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