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Proportionator
The proportionator is the most efficient unbiased stereological method used to estimate population size in samples. A typical application is counting the number of cells in an organ. The proportionator is related to the optical fractionator and physical dissector methods that also estimate population. The optical and physical fractionators use a sampling method called systematic uniform random sampling, or SURS. Unlike these two methods the proportionator introduces sampling with probability proportional to size, or PPS. With SURS all sampling sites are equal. With PPS sites are not sampled with the same probability. The reason for using PPS is to improve the efficiency of the estimation process. Efficiency is the notion of how much is gained by a given amount of work. A more efficient method provides better results for the same amount of work. The proportionator provides a better estimate, that is a more precise estimate, than either of these two methods: the optical fractionat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter Bitterlich
Walter Bitterlich (; February 19, 1908 – February 9, 2008) was an Austrian forestry scientist. He was the inventor of the relascope, a method for efficient forest inventory. Early career Bitterlich descended from several generations of foresters and did much of his early work in the Tyrolean Alps of Austria. Walter Bitterlich was the son of the forester Ernst Bitterlich and his wife Maria née Wachtel. Despite his upbringing in relative poverty, he successfully completed a forestry degree at Vienna's University of Natural Resources and Life Sciences in 1930 and the state exam for Higher Forest Service in 1933. Failing to find regular employment, he started volunteering with the Austrian State Forestry Commission. National Socialism Bitterlich was an early member of the National Socialist German Workers' Party, joining in 1933 when it was illegal to do so in Austria. After the Anschluss of Austria in 1939 he became party member no. 511,075 (later changed to 1,618,531). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forestry
Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. The science of forestry has elements that belong to the biological, physical, social, political and managerial sciences. Forest management play essential role of creation and modification of habitats and affect ecosystem services provisioning. Modern forestry generally embraces a broad range of concerns, in what is known as multiple-use management, including: the provision of timber, fuel wood, wildlife habitat, natural water quality management, recreation, landscape and community protection, employment, aesthetically appealing landscapes, biodiversity management, watershed management, erosion control, and preserving forests as " sinks" for atmospheric carbon dioxide. Forest ecosystems have come to be seen as the most important componen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Forestry
The ''Journal of Forestry'' is the primary scholarly journal of the Society of American Foresters. It aims to advance the forestry profession by keeping professional foresters informed about developments and ideas related to the practice of forestry. The journal publishes editorials and technical content related to the management of forests and related natural resources. Articles are generally written for an audience of natural resources professionals, with topics spanning the many facets or disciplines of forestry. The ''Journal'' is currently edited by Keith A. Blatner. According to the ''Journal Citation Reports'', its 2018 impact factor is 2.675. History The origins of the ''Journal of Forestry'' go back to October 1902, when one of its predecessors, the ''Forestry Quarterly'', was first published at the New York State College of Forestry at Cornell University, in Ithaca, New York, under the editorial advisement of Bernhard E. Fernow, John Gifford, and Walter Mulford. L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Microscopy
The ''Journal of Microscopy'' is the monthly peer-reviewed scientific journal of the Royal Microscopical Society which covers all aspects of microscopy including spatially resolved spectroscopy, compositional mapping, and image analysis. This includes technology and applications in physics, chemistry, material science, and the life sciences. It is published by Wiley-Blackwell on behalf of the Society. The editor-in-chief is Michelle Peckham, a Cell Biology professor at University of Leeds. The journal publishes review articles, original research papers, short communications, and letters to the editor. It was established in 1841 as the ''Transactions of the Microscopical Society of London'', obtaining its current name in 1869, with volume numbering restarting at 1. Abstracting and indexing The journals is abstracted and indexed in: According to the ''Journal Citation Reports'', the journal has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variance
In probability theory and statistics, variance is the expectation of the squared deviation of a random variable from its population mean or sample mean. Variance is a measure of dispersion, meaning it is a measure of how far a set of numbers is spread out from their average value. Variance has a central role in statistics, where some ideas that use it include descriptive statistics, statistical inference, hypothesis testing, goodness of fit, and Monte Carlo sampling. Variance is an important tool in the sciences, where statistical analysis of data is common. The variance is the square of the standard deviation, the second central moment of a distribution, and the covariance of the random variable with itself, and it is often represented by \sigma^2, s^2, \operatorname(X), V(X), or \mathbb(X). An advantage of variance as a measure of dispersion is that it is more amenable to algebraic manipulation than other measures of dispersion such as the expected absolute deviation; for e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lou Grosenbaugh
Lewis R. (Lou) Grosenbaugh (November 4, 1913 – April 22, 2003) was a prominent U.S. Forest Service researcher and head of the Forest Service's first Pioneering Research Unit, in forest mensuration, in Berkeley, California. Known for his contributions to the fields of forest inventory, forest measurement, and forest management, Grosenbaugh built on Walter Bitterlich's idea of estimating the density of a forest with timber cruising so that individual trees could be used to estimate various stand measures, such as volume per acre. Career * 1936. U.S. Forest Service Junior Forester on the Ouachita National Forest * 1938 timber management assistant and assistant forester, Ozark National Forest * 1941 U.S. Naval Reserve, highest rank Lieutenant Commander * 1946 Associate Forester, National Forests in Florida * 1946 Silviculturist, Southern Forest Experiment Station, New Orleans * 1951 Division Chief of Forest Management Research, Forest Genetics Research, Forest Fire Researc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Gauge
An angle gauge is a tool used by foresters to determine which trees to measure when using a variable radius plot design in forest inventory. Using this tool a forester can quickly measure the trees that are in or out of the plot. An angle gauge is similar to a wedge prism though it must be held a fixed distance from the eye to work properly. Unlike the wedge prism, which is held over the plot center, the surveyor's eye is kept over plot-center when using an angle gauge. Use When using an angle gauge the user must count trees that are larger than the width of the angle gauge, as viewed from the center of the plot. The angle gauge is held a set distance from the eye of the surveyor. Most angle gauges have a string or chain that lets the user know the set distance. Each angle gauge is set at a certain basal area factor (BAF). Each tree that is in the plot represents this number, the BAF, of square footage. It is multiplied by the number of trees on the plot to give basal area per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrat
A quadrat is a frame, traditionally square, used in ecology, geography and biology to isolate a standard unit of area for study of the distribution of an item over a large area. Modern quadrats can for example be rectangular, circular, or irregular. The quadrat is suitable for sampling plants, slow-moving animals, and some aquatic organisms. A photo-quadrat is a photographic record of the area framed by a quadrat. It may use a physical frame to indicate the area, or may rely on fixed camera distance and lens field of view to automatically cover the specified area of substrate. Parallel laser pointers mounted on the camera can also be used as scale indicators. The photo is taken perpendicular to the surface, or as close as possible to perpendicular for uneven surfaces. History The systematic use of quadrats was developed by the pioneering plant ecologists R. Pound and F. E. Clements between 1898 and 1900. The method was then swiftly applied for many purposes in ecology, such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereology
Stereology is the three-dimensional interpretation of two-dimensional cross section (geometry), cross sections of materials or tissues. It provides practical techniques for extracting quantitative information about a three-dimensional material from measurements made on two-dimensional planar sections of the material. Stereology is a method that utilizes random, systematic sampling to provide unbiased and quantitative data. It is an important and efficient tool in many applications of microscopy (such as petrography, materials science, and biosciences including histology, bone and neuroanatomy). Stereology is a developing science with many important innovations being developed mainly in Europe. New innovations such as the proportionator continue to make important improvements in the efficiency of stereological procedures. In addition to two-dimensional plane sections, stereology also applies to three-dimensional slabs (e.g. 3D microscope images), one-dimensional probes (e.g. needle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Size
In population genetics and population ecology, population size (usually denoted ''N'') is the number of individual organisms in a population. Population size is directly associated with amount of genetic drift, and is the underlying cause of effects like population bottlenecks and the founder effect. Genetic drift is the major source of decrease of genetic diversity within populations which drives fixation and can potentially lead to speciation events. Genetic drift Of the five conditions required to maintain Hardy-Weinberg Equilibrium, infinite population size will always be violated; this means that some degree of genetic drift is always occurring. Smaller population size leads to increased genetic drift, it has been hypothesized that this gives these groups an evolutionary advantage for acquisition of genome complexity. An alternate hypothesis posits that while genetic drift plays a larger role in small populations developing complexity, selection is the mechanism by which la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sampling (statistics)
In statistics, quality assurance, and survey methodology, sampling is the selection of a subset (a statistical sample) of individuals from within a statistical population to estimate characteristics of the whole population. Statisticians attempt to collect samples that are representative of the population in question. Sampling has lower costs and faster data collection than measuring the entire population and can provide insights in cases where it is infeasible to measure an entire population. Each observation measures one or more properties (such as weight, location, colour or mass) of independent objects or individuals. In survey sampling, weights can be applied to the data to adjust for the sample design, particularly in stratified sampling. Results from probability theory and statistical theory are employed to guide the practice. In business and medical research, sampling is widely used for gathering information about a population. Acceptance sampling is used to determine if ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonuniform Sampling
Nonuniform sampling is a branch of sampling theory involving results related to the Nyquist–Shannon sampling theorem. Nonuniform sampling is based on Lagrange interpolation and the relationship between itself and the (uniform) sampling theorem. Nonuniform sampling is a generalisation of the Whittaker–Shannon–Kotelnikov (WSK) sampling theorem. The sampling theory of Shannon can be generalized for the case of nonuniform samples, that is, samples not taken equally spaced in time. The Shannon sampling theory for non-uniform sampling states that a band-limited signal can be perfectly reconstructed from its samples if the average sampling rate satisfies the Nyquist condition. Therefore, although uniformly spaced samples may result in easier reconstruction algorithms, it is not a necessary condition for perfect reconstruction. The general theory for non-baseband and nonuniform samples was developed in 1967 by Henry Landau. He proved that the average sampling rate (uniform or other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
