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Ecological Orbits
''Ecological Orbits: How Planets Move and Populations Grow'' is a book on population ecology by ecologist Lev R. Ginzburg and philosopher of science Mark Colyvan that argues for an inertial model of population dynamics. Summary The book is divided into eight chapters, each of which advances Ginzburg and Colyvan's argument for an inertial model of population dynamics. It begins with an explanation of planetary orbits and population growth, and argues that an analogy between the two might be fruitful for theoretical ecology. Chapter 2 engages in the debate over whether or not ecology can have laws of nature akin to those of physics by comparing ecological allometries such as Kleiber's law with Kepler's laws of planetary motion. Ginzburg and Colyvan argue that ecological allomotries cannot be discounted as laws of nature they are not always exceptionless, predictive, falsifiable, or distinguishable from accidental regularities as such concerns would also rule out physical laws. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lev R
Lev may refer to: Common uses *Bulgarian lev, the currency of Bulgaria *an abbreviation for Leviticus, the third book of the Hebrew Bible and the Torah People and fictional characters *Lev (given name) *Lev (surname) Places *Lev, Azerbaijan, a village * Lev (crater), a tiny lunar crater LEV *Laborious Extra-Orbital Vehicle, a mecha from the video game ''Zone of the Enders'' *Lay eucharistic visitor, an extraordinary minister of Holy Communion approved by a church (usually Episcopalian or Lutheran) to bring Communion to the homebound *Libreria Editrice Vaticana, the Vatican Publishing House *Light electric vehicle, an electric bicycle * Local exhaust ventilation, the process of "changing" or replacing air to improve indoor air quality *Low emission vehicle, a motor vehicle that emits relatively low levels of motor vehicle emissions *Lunar Excursion Vehicle, an early name for the Apollo Lunar Module *Longevity escape velocity, a hypothetical situation wherein the average human li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larry Slobodkin
Lawrence Basil Slobodkin (June 22, 1928 – September 12, 2009) was an American ecologist and Professor Emeritus at the Department of Ecology and Evolution, Stony Brook University, State University of New York. He was one of the leading pioneers of modern ecology. His innovative thinking and research, provocative teaching, and visionary leadership helped transform ecology into a modern science, with deep links to evolution. Biography Slobodkin was born in 1928 in the Bronx, son of Louis Slobodkin and Florence (Gersh) Slobodkin. He was strongly influenced by the artistic, intellectual, cultural, and political milieu in which he developed; his mother was a writer and his father a noted sculptor who later became a well-known illustrator and writer who received the distinguished Caldecott Award for his watercolor illustrations of the children's book, ''Many Moons'' as well as biographies of the legendary revolutionaries Garibaldi and Lenin. While absorbing the lessons of art a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damped Oscillator
In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force ''F'' proportional to the displacement ''x'': \vec F = -k \vec x, where ''k'' is a positive constant. If ''F'' is the only force acting on the system, the system is called a simple harmonic oscillator, and it undergoes simple harmonic motion: sinusoidal oscillations about the equilibrium point, with a constant amplitude and a constant frequency (which does not depend on the amplitude). If a frictional force (damping) proportional to the velocity is also present, the harmonic oscillator is described as a damped oscillator. Depending on the friction coefficient, the system can: * Oscillate with a frequency lower than in the undamped case, and an amplitude decreasing with time (underdamped oscillator). * Decay to the equilibrium position, without oscillations (overdamped oscillator). The boundary solution between an underdamped os ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotonic Function
In mathematics, a monotonic function (or monotone function) is a function between ordered sets that preserves or reverses the given order. This concept first arose in calculus, and was later generalized to the more abstract setting of order theory. In calculus and analysis In calculus, a function f defined on a subset of the real numbers with real values is called ''monotonic'' if and only if it is either entirely non-increasing, or entirely non-decreasing. That is, as per Fig. 1, a function that increases monotonically does not exclusively have to increase, it simply must not decrease. A function is called ''monotonically increasing'' (also ''increasing'' or ''non-decreasing'') if for all x and y such that x \leq y one has f\!\left(x\right) \leq f\!\left(y\right), so f preserves the order (see Figure 1). Likewise, a function is called ''monotonically decreasing'' (also ''decreasing'' or ''non-increasing'') if, whenever x \leq y, then f\!\left(x\right) \geq f\!\left(y\ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exponential Growth
Exponential growth is a process that increases quantity over time. It occurs when the instantaneous rate of change (that is, the derivative) of a quantity with respect to time is proportional to the quantity itself. Described as a function, a quantity undergoing exponential growth is an exponential function of time, that is, the variable representing time is the exponent (in contrast to other types of growth, such as quadratic growth). If the constant of proportionality is negative, then the quantity decreases over time, and is said to be undergoing exponential decay instead. In the case of a discrete domain of definition with equal intervals, it is also called geometric growth or geometric decay since the function values form a geometric progression. The formula for exponential growth of a variable at the growth rate , as time goes on in discrete intervals (that is, at integer times 0, 1, 2, 3, ...), is x_t = x_0(1+r)^t where is the value of at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Logarithm
The natural logarithm of a number is its logarithm to the base of the mathematical constant , which is an irrational and transcendental number approximately equal to . The natural logarithm of is generally written as , , or sometimes, if the base is implicit, simply . Parentheses are sometimes added for clarity, giving , , or . This is done particularly when the argument to the logarithm is not a single symbol, so as to prevent ambiguity. The natural logarithm of is the power to which would have to be raised to equal . For example, is , because . The natural logarithm of itself, , is , because , while the natural logarithm of is , since . The natural logarithm can be defined for any positive real number as the area under the curve from to (with the area being negative when ). The simplicity of this definition, which is matched in many other formulas involving the natural logarithm, leads to the term "natural". The definition of the natural logarithm can then b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time Derivative
A time derivative is a derivative of a function with respect to time, usually interpreted as the rate of change of the value of the function. The variable denoting time is usually written as t. Notation A variety of notations are used to denote the time derivative. In addition to the normal ( Leibniz's) notation, :\frac A very common short-hand notation used, especially in physics, is the 'over-dot'. I.E. :\dot (This is called Newton's notation) Higher time derivatives are also used: the second derivative with respect to time is written as :\frac with the corresponding shorthand of \ddot. As a generalization, the time derivative of a vector, say: : \mathbf v = \left v_1,\ v_2,\ v_3, \ldots \right is defined as the vector whose components are the derivatives of the components of the original vector. That is, : \frac = \left \frac,\frac ,\frac , \ldots \right . Use in physics Time derivatives are a key concept in physics. For example, for a changing position x, its t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cohort Effect
The term cohort effect is used in social science to describe variations in the characteristics of an area of study (such as the incidence of a characteristic or the age at onset) over time among individuals who are defined by some shared temporal experience or common life experience, such as year of birth, or year of exposure to radiation. Cohort effects are important to epidemiologists searching for patterns in illnesses. Certain illnesses may be socially affected via the anticipation phenomenon, and cohort effects can be an indicator of this sort of phenomenon. Cohort effects are important to resource dependency, and economics theorists when these groups affect structures of influence within their larger organizations. Cohorts in organizations are often defined by entry or birth date, and they retain some common characteristic (size, cohesiveness, competition) that can affect the organization. For example, cohort effects are critical issues in school enrollment. In order to de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Age Structure
A population pyramid (age structure diagram) or "age-sex pyramid" is a graphical illustration of the distribution of a population (typically that of a country or region of the world) by age groups and sex; it typically takes the shape of a pyramid when the population is growing. Males are usually shown on the left and females on the right, and they may be measured in absolute numbers or as a percentage of the total population. The pyramid can be used to visualize the age of a particular population. It is also used in ecology to determine the overall age distribution of a population; an indication of the reproductive capabilities and likelihood of the continuation of a species. Number of people per unit area of land is called population density. Structure A population pyramid often contains continuous stacked-histogram bars, making it a horizontal bar diagram. The population size is shown on the x-axis (horizontal) while the age-groups are represented on the y-axis (vertical). The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Quarterly Review Of Biology
''The Quarterly Review of Biology'' is a peer-reviewed scientific journal covering all aspects of biology. It was established in 1926 by Raymond Pearl. In the 1960s it was purchased by the Stony Brook Foundation when the editor H. Bentley Glass became academic vice president of Stony Brook University. The editor-in-chief is Daniel E. Dykhuizen (Stony Brook University). It is currently published by the University of Chicago Press. Aims and scope The journal publishes review articles. Beyond the core biological sciences, the journal also covers related areas, including policy studies and the history and philosophy of science. There is also a book review section. Abstracting and indexing The journal is abstracted and indexed in Biological Abstracts, BIOSIS Previews, and the Science Citation Index The Science Citation Index Expanded – previously entitled Science Citation Index – is a citation index originally produced by the Institute for Scientific Information (ISI) and creat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ad Hoc Hypothesis
In science and philosophy, an ''ad hoc'' hypothesis is a hypothesis added to a theory in order to save it from being falsified. Often, ''ad hoc'' hypothesizing is employed to compensate for anomalies not anticipated by the theory in its unmodified form. In the scientific community Scientists are often skeptical of theories that rely on frequent, unsupported adjustments to sustain them. This is because, if a theorist so chooses, there is no limit to the number of ''ad hoc'' hypotheses that they could add. Thus the theory becomes more and more complex, but is never falsified. This is often at a cost to the theory's predictive power, however. ''Ad hoc'' hypotheses are often characteristic of pseudoscientific subjects. An ''ad hoc'' hypothesis is not necessarily incorrect; in some cases, a minor change to a theory was all that was necessary. For example, Albert Einstein's addition of the cosmological constant to general relativity in order to allow a static universe was ''ad hoc''. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overfitting
mathematical modeling, overfitting is "the production of an analysis that corresponds too closely or exactly to a particular set of data, and may therefore fail to fit to additional data or predict future observations reliably". An overfitted model is a mathematical model that contains more parameters than can be justified by the data. The essence of overfitting is to have unknowingly extracted some of the residual variation (i.e., the noise) as if that variation represented underlying model structure. Underfitting occurs when a mathematical model cannot adequately capture the underlying structure of the data. An under-fitted model is a model where some parameters or terms that would appear in a correctly specified model are missing. Under-fitting would occur, for example, when fitting a linear model to non-linear data. Such a model will tend to have poor predictive performance. The possibility of over-fitting exists because the criterion used for selecting the model is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
