Gradient descent is a First order approximation first order Mathematical optimization optimization algorithm . To find a local minimum of a function using gradient descent, one takes steps proportional to the negative of the gradient or of the approximate gradient of the function at the current point. If instead one takes steps proportional to the positive of the gradient , one approaches a local maximum of that function the procedure is then known as gradient ascent . Gradient descent is also known as steepest descent , or the method of steepest descent . When known as the latter, gradient descent ... Image gradient descent.png thumb right 350px Illustration of gradient descent Gradient descent ... of the negative gradient of math F math at math mathbf a math , math nabla F mathbf a math . It follows ... in this case gradient descent can converge to the global solution. This process is illustrated in the picture ... gradient at that point. Note that the negative gradient at a point is orthogonal to the contour line going through that point. We see that gradient descent leads us to the bottom of the bowl, that is, to the point where the value of the function math F math is minimal. Examples Gradient descent ... 400px The Zig Zagging nature of the method is also evident below, where the gradient ascent method is applied to math F x,y sin left frac 1 2 x 2 frac 1 4 y 2 3 right cos 2 x 1 e y math . Image gradient ascent contour .png 350px The gradient descent algorithm in action. 1 contour Image gradient ascent surface .png 450px The gradient descent algorithm in action. 2 surface Limitations For some of the above examples, gradient descent is relatively slow close to the minimum technically, its asymptotic ..., gradient descent increasingly zigzags as the gradients point nearly orthogonally to the shortest direction to a minimum point. For more details, see the Gradient descent Comments comments below. For non differentiable functions, gradient methods are ill defined. For locally Lipschitz continuity Lipschitz ... more details
with hilliness, road sections with risk for insufficient drainage gradient are few and short ... . How to avoid or minimize skid risk caused by insufficient drainage gradient Roads should be designed ... gradient 0.5 , resulting in unacceptable skid accident risk. When designing road curves in a flat ... gradients can then be used to reach a sufficient drainage gradient, in sections where the cross ... Final Report DEFAULTSORT Drainage Gradient Category Pavement engineering ... more details
Density gradient is a spatial variation in density over an area. The term is used in the natural sciences to describe varying density of matter , but can apply to any quantity whose density can be measured . ref cite web title Non Destructive Testing Resource Center Glossary url http www.ndt ed.org GeneralResources Glossary letter d.htm ref ref cite web title Chicago Wilderness Journal, Volume 1 Number 1 November, 2003 url http www.chicagowilderness.org pubprod cwjournal docs CWJournal1003.pdf ref Aerodynamics In the study of supersonic flight, Schlieren photography observes the density gradient of air as it interacts with aircraft. ref cite web title CFI Shadowgraph Schliren Photography for Aerodynamic Applications url http pdf.aiaa.org preview 1994 PV1994 2616.pdf ref Water A steep density gradient in a body of water can have the effect of trapping energy and preventing convection , such a gradient is employed in solar pond s. In the case of salt water, sharp gradients can lead to Stratification water stratification of different concentrations of salinity . This is called a Halocline . ref cite web title Effects of sill processes and tidal forcing on exchange in eastern Long Island Sound url http www.agu.org pubs crossref 1994 94JC00721.shtml ref Biology In the life sciences, a special technique called density gradient separation is used for isolating and purifying cells, viruses and subcellular particles. ref cite web title GE Healthcare Density Gradient Separation url http www6.amershambiosciences.com aptrix upp00919.nsf Content CellSep EduC dgs ref Variations of this include Isopycnic centrifugation , Differential centrifugation , and Sucrose gradient centrifugation . A blood donation technique called Pheresis involves density gradient separation. Geophysics The understanding ... is one theory by reason of density gradient and supported and espoused by http www.pnas.org ..., the density gradient can refer to the change in density in an urban area from the center to the periphery ... more details
Gradient noise is a type of noise commonly used as a procedural texture primitive in computer graphics. It is conceptually different, and often confused with value noise . This method consists of a creation of a lattice of random gradients , which are then interpolated to obtain values in between the lattices. An artifact of some implementations of this noise is that the returned value at the lattice points is 0. Unlike the value noise, gradient noise has more energy in the high frequencies. The first implementation of a gradient noise function is credited to Ken Perlin , who published the description of it in 1985. This noise is now commonly known as the Perlin noise . ref David Ebert, Kent Musgrave, Darwyn Peachey, Ken Perlin, and Worley. Texturing and Modeling A Procedural Approach. Academic Press, October 1994. ISBN 0 12 228760 6 ref See also Value noise Perlin noise Simplex noise Wavelet noise Worley noise References reflist Category Noise Category Computer graphic techniques graphics software stub ru ... more details
Gradient Analytics, Inc. , founded in 1996 by Donn Vickrey and Dr. Carr Bettis as Camelback Research Alliance, Inc. and based in Scottsdale, Arizona , is an independent securities research equity research company. ref http investing.businessweek.com research stocks private snapshot.asp?privcapId 11517448 Gradient Analytics, Inc. , profile at BusinessWeek ref References references External links http www.marketwatch.com news story story.aspx?guid 7B83FE0B79 0B4A 45DE AF4E 1C1E3EAEEEA2 7D Category Companies based in Scottsdale, Arizona Category Companies established in 1996 Category Financial services companies of the United States finance company stub ... more details
Multiple issues orphan February 2009 context June 2009 cleanup June 2009 A gradient network is a directed subnetwork of an undirected substrate computer network network in which each node networking node has an associated scalar potential and one out link that point to the node with the smallest or largest potential in its neighborhood, defined as the reunion of itself and its nearest neighbors on the substrate networks. ref name grad2 Bogdan Danila, Congestion gradient driven transport on complex networks, PHYSICAL REVIEW E 74, 046114 2006 ref Let us consider that transport takes place on a fixed ... j V i,j E . Image gnt.jpg thumb 250px right Fig.3. An example of gradient network. ref name toro ... V, so that every node i has a scalar value h sub i sub associated to it. Gradient h sub i sub ... sup 1 sup i , and h sub sub has the maximum value in math h j j in S i 1 cup i math . Gradient network math G math math G math math V, F math where F is the set of gradient edges on G . In general ..., the gradient network math G math will be dynamic. Motivation Real world networks evolve to fulfill ... gradients of a scalar, for example electric current driven by a gradient of electric potential in the information ... from a node to its neighbors. This idea motivated the approach through gradient networks which .... Gradient Networks, cond mat 0408262. ref Image Gradient.jpg thumb 300px left Fig.2. The gradient ... s neighborhood. ref name toro In degree distribution of gradient networks In a gradient network, in degree of a node i, k sub i sub sup in sup is the number of gradient edges pointing into i ... 200px left Fig.5. The degree distributions of the gradient network and the substrate BA Model . ref ... the power law center math R l approx l 1 math center This shows in this limit, the gradient network of random network is scale free. If the subtstrate network G is scale free, like BA model, then the gradient ... gradient flow and N sub send sub is the number of nodes that send the flow. The value of J is in the range ... more details
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in Units of measurement units of degrees on a particular temperature scale per unit length. The International System of Units SI unit is kelvin per meter K m . Temperature gradients in the Earth s atmosphere atmosphere are important in the atmospheric sciences meteorology , climatology and related fields . Mathematical description Assuming that the temperature T is an intensive quantity , i.e., a single valued, Continuous function continuous and Derivative differentiable Function mathematics function of three dimensional space often called a scalar field , i.e., that math T T x,y,z math where x , y and z are the Cartesian coordinate system coordinates of the location of interest, then the temperature gradient is the vector geometric vector quantity defined as math nabla T begin pmatrix frac partial T partial x , frac partial T partial y , frac partial T partial z end pmatrix math ... Weather and climate relevance Differences in air temperature between different locations are critical in weather forecasting and climate. The absorption of solar light at or near the planetary surface increases the temperature gradient and may result in convection a major process of cloud formation, often associated with Precipitation meteorology precipitation . Similarly ... fronts are regions where the horizontal temperature gradient may reach relatively high values, as these are boundaries ... gradient may change substantially in time, as a result of diurnal or seasonal heating and cooling ... in space or time may cause discomfort and, in extreme cases, heat or cold stresses. See also Gradient ... IPCC Third Assessment Report Category Atmospheric dynamics Category Climatology ca Gradient t rmic ... pl Pionowy gradient temperatury pt Gradiente de temperatura zh ... more details
In mathematics , the gradient conjecture , due to Ren Thom , was proved in 2000 by 3 Polish mathematicians, Krzysztof Kurdyka University of Savoie , France , Tadeusz Mostowski Warsaw University , Poland and Adam Parusinski University of Angers , France . It states that given a real valued analytic function f defined on R sup n sup and a trajectory x t of the gradient vector field of f having a limit point x sub 0 sub R sup n sup , where f has an isolated critical point at x sub 0 sub , there exists a limit in the projective space PR sup n 1 sup for the secant lines from x t to x sub 0 sub , as t tends to zero. References A published statement of the conjecture R. Thom, Probl mes rencontr s dans mon parcours math matique un bilan, Publ. Math. IHES 70 1989 , 200 214. This gradient conjecture due to Ren Thom was in fact well known among specialists by the early 70 s, having been often discussed during that period by Thom during his weekly seminar on singularities at the IHES . The paper where it is proved Annals of Math. 152 2000 , 763 792. It is available http arxiv.org abs math.AG 9906212 here . Category Mathematical analysis Category Theorems in analysis Mathanalysis stub ... more details
Gradient boosting is a machine learning technique for Regression machine learning regression problems ... differentiable loss function . Gradient boosting method can be also used for classification machine ... Function Approximation A Gradient Boosting Machine. February 1999 ref introduced the method, and the second ... Stochastic Gradient Boosting. March 1999 ref described an important tweak to the algorithm, which improves its accuracy and performance. Gradient boosting In many supervised learning problems one has ... Gradient boosting method assumes a real valued y and seeks an approximation math hat F x math in the form ... allows us to generalize , we ll just choose the one that most closely approximates the gradient of L ... equation above. In pseudocode, the generic gradient boosting method is ref name Friedman1999a ref name ... F m x F m 1 x gamma m h m x . math Output math F M x . math frame footer Gradient tree boosting Gradient ... trees of a fixed size as base learners. For this special case Friedman proposes a modification to gradient boosting method which improves the quality of fit of each base learner. Generic gradient .... One natural regularization parameter is the number of gradient boosting iterations M i.e. the number ... other regularization techniques are used. Shrinkage An important part of gradient boosting method ... yields dramatic improvements in model s generalization ability over gradient boosting without shrinking ... both during training and querying lower learning rate requires more iterations. Stochastic gradient boosting Soon after the introduction of gradient boosting Friedman proposed a minor modification to the algorithm ... set. ref Friedman observed a substantional improvement in gradient boosting s accuracy ... to the gbm package. ref Number of observations in leaves Gradient tree boosting implementations often .... Usage Recently, gradient boosting method has gained some popularity in learning to rank field ... corporate blog entry about new ranking model Snezhinsk in Russian ref use variants of gradient boosting ... more details
orphan date June 2010 Refers to the gradient created in the nephron s of the kidney s, between the tubules and the interstitial fluid surrounding them. It is created by the solutes urea and salt exiting and reentering the tubules at different sections of the nephron. The selective permeability of the tubules is a major factor in this process. Tissue osmolarity increases from Cortex anatomy cortex outer layar of a nephron , to inner renal medulla middle layer of a nephron . Category Renal physiology ... more details
In mathematical morphology and digital image processing , a morphological gradient is the difference between the dilation morphology dilation and the erosion morphology erosion of a given image. It is an image where each pixel value typically non negative indicates the contrast intensity in the close neighborhood of that pixel. It is useful for edge detection and Segmentation image processing segmentation applications. Mathematical definition and types Let math f E mapsto R math be a grayscale image, mapping points from a Euclidean space or discrete grid E such as R sup 2 sup or Z sup 2 sup into the real line. Let math b x math be a grayscale structuring element . Usually, b is symmetry symmetric and has short support , e.g., math b x left begin array ll 0,& x leq 1, infty,& mbox otherwise end array right. math . Then, the morphological gradient of f is given by math G f f oplus b f ominus b math , where math oplus math and math ominus math denote the dilation and the erosion, respectively. An internal gradient is given by math G i f f f ominus b math , and an external gradient is given by math G e f f oplus b f math . The internal and external gradients are thinner than the gradient, but the gradient peaks are located on the edges, whereas the internal and external ones are located at each side of the edges. Notice that math G i G e G math . If math b 0 geq 0 math , then all the three gradients have non negative values at all pixels. References cite id serra82 Image Analysis and Mathematical Morphology by Jean Serra, ISBN 0126372403 1982 cite Image Analysis and Mathematical Morphology, Volume 2 Theoretical Advances by Jean Serra, ISBN 0 12 637241 1 1988 An Introduction to Morphological Image Processing by Edward R. Dougherty, ISBN 0 8194 0845 X 1992 External links http cmm.ensmp.fr beucher publi morph grad.pdf Morphological gradients , Centre de Morphologie Math matique, cole des Mines de Paris Category Mathematical morphology Category Digital geometry compu graphics ... more details
In differential geometry , the four gradient is the four vector generalization of the gradient . Definition The covariant components compactly written in index notation are ref The Cambridge Handbook of Physics Formulas, G. Woan, Cambridge University Press, 2010, ISBN 978 0 521 57507 2 ref math dfrac partial partial x alpha left frac 1 c frac partial partial t , nabla right partial alpha , alpha math The comma in the last part above math , alpha math implies the partial differentiation with respect to math x alpha math . This is not the same as a semi colon, used for the covariant derivative . The contravariant components are ref The Cambridge Handbook of Physics Formulas, G. Woan, Cambridge University Press, 2010, ISBN 978 0 521 57507 2 ref math partial alpha g alpha beta partial beta left frac 1 c frac partial partial t , nabla right math where g sup sup is the Metric tensor general relativity metric tensor , which here has been chosen for flat spacetime with the metric signature , , , . Alternative symbols to math partial alpha math is math Box math or D . Usage The square of D is the four Laplacian , which is called the d Alembert operator math D cdot D partial alpha partial alpha frac 1 c 2 frac partial 2 partial t 2 nabla 2 math . As it is the dot product of two four vectors, the d Alembertian is a Lorentz invariant scalar. Occasionally, in analogy with the 3 dimensional notation, the symbols math Box math and math Box 2 math are used for the 4 gradient and d Alembertian respectively. More commonly however, the symbol math Box math is reserved for the d Alembertian. Derivation In 3 dimensions, the gradient operator maps a scalar field to a vector field such that the line integral between any two points in the vector field is equal to the difference between the scalar ... of the gradient to four dimensions should be math partial alpha left frac partial partial t , nabla ... gives the correct definition of four gradient math partial alpha left frac 1 c frac partial partial ... more details
Engineering Hay says The ruling grade may be defined as the maximum gradient over which a tonnage ... gradient on the division. Momentum grades, pusher grades, or those that must regularly be doubled ... compensate for this, the gradient should be a little less steep the sharper the curve is the necessary ... is analogous to compensation for curvature and requires the gradient in the tunnel and for some ... compensation for gradient is not a simple equation, but is rather a trial and error process. Since ... on the first Cascade Tunnel , too little compensation for tunnel gradient was made. It is worthwhile .... The lines approaching the first cascade tunnel had a ruling gradient of 2.2 1 in 45.5 , while the tunnel itself had a gradient of 1.7 1 in 58.8 facing eastbound trains. This gradient appears to be chosen .... Even though the ruling gradient in the tunnel was slightly less than that on the tracks on either ... say 1 in 400 or 0.25 , with a very steep section in the open air on the western approaches. The gradient .... Strictly speaking, the level gradient should continue for a suitable distance beyond the portal ... minimum smoke. The tunnel should have a slight gradient to facilitate drainage of water. Open ... gradient, a better solution would have been to have a level tunnel from New Tye West to Cascade Tunnel Station West , with a 2.6 mile stretch of say 4 gradient 1 in 25 on the western approaches from ..., this tunnel was on a steep gradient, indeed the ruling grade of 1 in 33, which caused problems with the smoke ... have a relatively gentle gradient of 1 in 90 1.11 . However, the frequent gaps between the tunnels ... conditions as the gradient of 1 in 200 0.5 Percent sign in the tunnel was not sufficiently reduced ... Dividing Range . It is not known how winds would affect the fume issue. Curve and Gradient Books ... more details
Gradient analysis is an empirical analytical method used in plant community ecology to relate the abundances of various species in a plant community to various environmental gradients by Ordination statistics ordination or by Weighted mean weighted averaging . These gradients are usually Variable mathematics variables that are important in plant species distributions, and include temperature, water availability, light, and soil nutrients, or their closely correlated surrogates. References Mike Palmer, http ordination.okstate.edu Ordination Methods for Ecologists Botany Department of Oklahoma State University. Retrieved 15 August 2010. ecology stub modelling ecosystems expanded other Category Community ecology ... more details
multiple issues orphan May 2010 unreferenced May 2010 notability May 2010 A redox gradient is the biogeochemical sorting of reductant s and oxidants according to redox potential , with the most reducing conditions at depth, having its origin in the depletion of oxygen and the successive depletion of reactants with depth. They form in Stratification water stratified environments where oxygen does not penetrate deeper than the immediate surface environment. Examples include waterlogged soil s, marine pelagic and hemipelagic sediments, and, most notably, the Black Sea . Category Chemical reactions Category Chemical nomenclature Category Coordination chemistry ... more details
calculus cTopic Vector calculus The gradient theorem , also known as the fundamental theorem of calculus for line integrals , says that a line integral through a gradient field any irrotational vector field conservative vector field can be expressed as the gradient of a scalar field can be evaluated by evaluating the original scalar field at the endpoints of the curve math phi left mathbf q right phi left mathbf p right int gamma mathbf p , mathbf q nabla phi mathbf r cdot d mathbf r . math It is a generalization of the fundamental theorem of calculus to any curve in a plane or space generally n dimensional rather than just the real line, and it is also a special case of the more general Stokes Theorem . The gradient theorem implies that line integrals through irrotational vector fields are Conservative vector field Path independence path independent . In physics this theorem is one of the ways of defining a Conservative force conservative force . By placing math phi math as potential, math nabla phi math is a conservative field . Work done by conservative forces does not depend on the path followed by the object, but only the end points, as the above equation shows. Proof If math phi math is a differentiable function differentiable function from some connected space connected subset of math mathbb R n math to math mathbb R math , and if math mathbf r math is a continuous function continuous function from some connected subset of math mathbb R math to math mathbb R n math , then by the the multivariate chain rule The chain rule in higher dimensions chain rule , math frac d dt phi mathbf r t nabla phi mathbf r t cdot mathbf r t , math where math cdot math is the usual dot product . Therefore, if math mathbf r math parametrization parametrizes the continuous curve math gamma math with endpoints math mathbf p math and math mathbf q math orientability oriented in the direction ... teoremo fa fr Th or me du gradient it Teorema del gradiente ... more details
Unreferenced stub auto yes date December 2009 Magnetic pressure is an energy density associated with the magnetic field . It is identical to any other physical pressure except that it is carried by the magnetic field rather than in the case of gas kinetic energy of the gas molecules. Interplay between magnetic pressure and ordinary gas pressure is important to both the fields of magnetohydrodynamics and plasma physics . Any magnetic field has an associated pressure that is contained by the boundary conditions on the field, and a gradient in field strength causes a force due to the magnetic pressuregradient this force is called the magnetic pressure force . The magnetic pressure force is most readily observed in an unsupported loop of wire if an electric current passes through the loop, then the wire serves as an electromagnet , so that the magnetic field strength inside the loop is much greater than the field strength just outside the loop. The gradient in field strength gives rise to a magnetic pressure force that tends to stretch the wire uniformly outward. If enough current travels through the wire, then the loop of wire will form a circle . At even higher currents, the magnetic pressure can create tensile stress that exceeds the tensile strength of the wire itself, causing it to fracture or even explosively fragment. Management of magnetic pressure is a significant challenge in the design of ultrastrong electromagnets. Magnetic pressure can be used to propel projectiles this is the operating principle of a railgun . If any currents present are parallel to the field, the magnetic field lines follow shapes in which the magnetic pressuregradient is exactly balanced by the magnetic tension force . Such a field configuration is called force free magnetic field force free ... current at all. The magnetic pressure math P B math is given in International System of Units ... Magnetic Pressure Category Plasma physics Physics stub de Magnetischer Druck fr Pression ... more details
Pulse Pressure is most easily defined as being the amount of pressure required to create the feeling of a pulse. Measured in millimeters of mercury mmHg , the pressure difference between the systolic and diastolic pressures give you the amount of pressure change to create the pulse, which is the pulse pressure. If your resting blood pressure is systolic diastolic 120 80 millimeters of mercury mmHg , your pulse pressure is 40 which is considered a normal and healthy pulse pressure. ref A review of educational ... pressure minus the diastolic pressure. ref http highbloodpressure.about.com od highbloodpressure101 p pulse pressure.htm ref Theoretically, the systemic pulse pressure can be conceptualized as being ... BP003.htm Arterial pulse pressure Bot generated title ref The aorta has the highest compliance ... ventricle, thereby reducing the pulse pressure. If the aorta becomes rigid in conditions such as arteriosclerosis or atherosclerosis , the pulse pressure would be very high. Systemic pulse pressure P sub systolic sub P sub diastolic sub 120mmHg 80mmHg 40mmHg Pulmonary pulse pressure P sub systolic sub P sub diastolic sub 25mmHg 10mmHg 15mmHg Values and variation Low Narrow Pulse Pressure A pulse pressure is considered abnormally low if it is less than 25 of the systolic value. The most common cause of a low narrow pulse pressure is a drop in left ventricular stroke volume. In trauma a low or narrow pulse pressure suggests significant blood loss insufficient preload leading to reduced ... 31 6 oclc doi accessdate ref If the pulse pressure is extremely low, i.e. 25 mmHg or less, the cause ... pulse pressure is also caused by aortic valve stenosis and cardiac tamponade . High Wide Pulse Pressure High values during or shortly after exercise Usually, the resting pulse pressure in healthy adults, sitting position, is about 60 80 mmHg . The pulse pressure increases with exercise due to increased ... IN MEDICAL STUDENTS BY PULSE PRESSURE METHOD , Farida Munawar, Fareeha, Maryam, Sana, Anushe, Nida ... more details
plant Root pressure is osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of some vascular plant s when ... is high, xylem sap is usually under tension, rather than under pressure, due to transpirational pull . At night in some plants, root pressure causes guttation or exudation of drops of xylem sap from the tips or edges of leaves. Root pressure is studied by removing the shoot of a plant near the soil level. Xylem sap will exude from the cut Plant stem stem for hours or days due to root pressure. If a pressure gauge is attached to the cut stem, the root pressure can be measured Root pressure ... . Water then diffuses from the soil into the root xylem due to osmosis . Root pressure is caused by this accumulation of water in the xylem pushing on the rigid cells. Root pressure provides a force ... at the top of the tallest tree s. The maximum root pressure measured in some plants can raise water ... in the root is important in the development of root pressure. The endodermis is a single layer ... gradient and by osmosis, water diffuses from the moist soil, across the cortex, through the endodermis and into the xylem. Importance Root pressure can transport water and dissolved mineral nutrients .... The maximum root pressure measured is about 0.6 Pascal unit megapascals but some species never generate any root pressure. The main contributor to the movement of water and mineral nutrients upward ... over winter. Root pressure may be important in refilling the xylem vessels. ref Sperry, J.S., Holbrook ... ref However, in some species vessels refill without root pressure. ref Tibbetts, T.J. and Ewers, F.W. 2000. Root pressure and specific conductivity in temperate lianas exotic Celastrus orbiculatus ... cgi content full 87 9 1272 ref Root pressure is often high in some deciduous trees before ... to root pressure only sugars, rather than ions, may lower the xylem water potential. In the unique ... more details
pulse P text sys P text dias . math Arm leg gradient The arm leg blood pressuregradient is the difference ..., Khoury PR, Knilans TK title Development of exercise induced arm leg blood pressuregradient and abnormal ... r 4 math P Pressure drop gradient Viscosity l length of tube. In the case of vessels with infinitely ... of velocity, rate of flow and viscous drag in arteries when the pressuregradient is known journal ...for information about high blood pressure Hypertension Diagnostic infobox Name Blood pressure Image Blutdruck.jpg Alt Caption A sphygmomanometer , a device used for measuring arterial pressure. DiseasesDB ... pressure BP is the pressure exerted by circulating blood upon the walls of blood vessel s, and is one of the principal vital signs . When used without further specification, blood pressure usually refers to the arterial pressure of the systemic circulation . During each heartbeat, blood pressure varies between a maximum Systole medicine systolic and a minimum diastolic pressure. ref cite web url http healthlifeandstuff.com 2010 06 normal blood pressure range adults title Normal Blood Pressure Range Adults publisher Health and Life ref The blood pressure in the circulation is principally due ... isbn 0 19 263323 6 oclc doi accessdate ref Differences in mean blood pressure are responsible for blood ... to flow presented by the blood vessels. Mean blood pressure decreases as the Circulatory ... due to Viscosity viscous losses of energy. Mean blood pressure drops over the whole circulation, although ... affects blood pressure via Fluid statics hydrostatic forces e.g. during standing and valves in veins, breathing , and pumping from contraction of skeletal muscles also influence blood pressure in veins. ref name Caro The measurement blood pressure without further specification usually refers to the systemic arterial pressure measured at a person s arm upper arm and is a measure of the pressure in the brachial artery , major artery in the upper arm. A person s blood pressure is usually expressed ... more details
Image Pressure solution sandstone.svg thumb 350px Schematic diagram of pressure solution accommodating compression compaction in a clastic rock . Left box shows the situation before compaction. Blue arrows indicate the flow of particles in solution. Red arrows indicate areas of maximum stress grain contacts . Right box shows the situation after compaction. In light coloured areas new mineral growth has reduced pore pore space . In structural geology and diagenesis , pressure solution or pressure dissolution is a deformation mechanism that involves the Solvation dissolution of minerals at grain to grain contacts into an Aqueous solution aqueous Porosity pore fluid in areas of relatively high Stress physics stress and either deposition in regions of relatively low stress within the same rock or their complete removal from the rock within the fluid. It is an example of diffusive mass transfer. ref Cite journal last Rutter first E.H. year 1983 title Pressure solution in nature, theory and experiment. journal Journal of the Geological Society, London volume 140 pages 725 740. url http jgs.lyellcollection.org cgi content abstract 140 5 725 accessdate 24 November 2010 issue 5 ref The detailed kinetics of the process was reviewed by Rutter, ref cite journal first E. H. last Rutter title The kinetics of rock deformation by pressure solution journal Phil. Trans. R. Soc. Lond. A. volume 283 ... been used in many applications ref Cite journal first X. S. last Yang title Pressure solution in sedimentary basins effect of temperature gradient journal Earth Planet. Sci. Lett. volume 176 pages ... 2010 ref in earth sciences. Occurrence Evidence for pressure solution has been described from sedimentary ... deformed rocks also show evidence of pressure solution including stylolites at a high angle ... first A. C. coauthors Yang X. S. year 1999 title Pressure solution and viscous compaction in sedimentary ... papers 1999.3.pdf accessdate 24 November 2010 ref which can explain the transition behaviour of pressure ... more details
Negative pressure may refer to Pressure Negative pressures negative pressure as opposed to positive pressure stretched liquid vacuum negative gauge pressure, a way of expressing pressure measurement s below atmospheric pressure suction transpirational pull See also pressure positive pressure disambig pt Press o negativa ... more details
Pressure Drop may refer to Pressure Drop song Pressure Drop song , by Toots & the Maytals, covered by many others Pressure Drop album Pressure Drop album , by Robert Palmer, released in 1975 Pressure Drop album Pressure Drop album , by Billy Bragg, released in 2010 See also Pressure drop , in pressure measurement disambig ... more details
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