Robuste schätzungen: Ein anwendungsorientierter Überblick

The paper offers an introductory survey of the area of robust estimation for applied statisticians, without demanding much mathematics. At first, the most important basic ideas of the robustness theory are explained using an example from the analysis of variance. Then the general reasons for and limits of the “robustification” of statistics are delineated. In particular, the various types of deviations from ideal models, such as gross errors, are discussed and their consequences are pointed out. The next part describes several simple robust estimators and their properties, ending with an outlook on robust estimators in linear models. As an appendix a number of frequent objections to and misunderstandings of robustness theory are discussed, refuted and clarified.     

Ultrastructural and biochemical studies of the swelling of developing chick telencephalic slices

Summary An ultrastructural and biochemical study of the importance and localization of tissue swelling was performed on telencephalic slices of 1- and 30-day-old chicks incubated in an oxygenated or a non-oxygenated physiological medium. The swelling of slices is greater for 30-day-old chick material than for that from 1-day-old chicks. It also reaches higher values in the non-oxygenated than in the oxygenated medium. When the 30-day-old chick telencephalic slices are incubated in an oxygenated medium, swelling mainly affects astrocytes, and especially the astrocytic endfeet. When they are incubated in a non-oxygenated medium, the astrocytes and astrocytic endfeet are very swollen and in addition the swelling also affects the neurons and their organelles. Extracellular space is increased. When 1-day-old chick telencephalic slices are incubated in a non-oxygenated medium, the tissue structures are well preserved. Swelling predominantly affects astrocytes and astrocytic endfeet. Neurons are not affected and the extracellular space is reduced. However, when they are incubated in an oxygenated medium, tissue structures are greatly affected showing a high degree of disorganization. Extracellular space is greatly increased. This study thus indicates that the best incubation conditions are an oxygenated medium for 30-day-old chick telencephalic slices which are characterized by an aerobic metabolism, and a non-oxygenated medium for 1-day-old chick telencephalic slices which have a predominantly anaerobic metabolism.     

An estimate of anisotropic poroelastic constants of an osteon

The anisotropic poroelastic constants of an osteon are estimated by micromechanical analysis. Two extreme cases are examined, the drained and the undrained elastic constants. The drained elastic constants are the porous medium’s effective elastic constants when the fluid in the pores easily escapes and the pore fluid can sustain no pore pressure. The undrained elastic constants are the porous medium’s effective elastic constants when the medium is fully saturated with pore fluid and the fluid cannot escape. The drained and undrained elastic constants at the lacunar and canalicular porosity tissue levels are estimated by using an effective moduli model consisting of the periodic distribution of ellipsoidal cavities. These estimated anisotropic poroelastic constants provide a database for the development of an accurate anisotropic poroelastic model of an osteon.     

Formation of an extracellular energy reserve byCellulomonas flavigena strain KU

Summary Conditions of growth are described which lead to the formation of a dense capsule aboutCellulomonas flavigena and provide data which suggest that, although accumulated as an extracellular structure, it may function as an energy reserve. The capsule is formed when the bacteria are cultured in a minimal medium containing an excess of one of several carbohydrates. The bacterial cells which are encapsulated are also densely aggregated. The capsule is not formed and the cells are not aggregated when the bacteria are cultured in complex growth media. The transfer of aggregated cells to a medium devoid of carbon and energy source results in disappearance of the capsule and disaggregation of the cells.     

The evolution of multicellularity in animals as a shift in biological autonomy

The hypothesis is advanced that major evolutionary innovations are characterized by an increase of organismal autonomy in the sense of an emancipation from the environment. After a brief overview of the literature on this concept, increasing autonomy is defined as the evolutionary shift in the individual system-environment relationship, so that the direct influences of the environment are gradually reduced and a stabilization of self-referential, intrinsic functions within the system is generated. This is described as relative autonomy because numerous interconnections with the environment and dependencies upon it are retained. Elements of an increasing autonomy are spatial separations, an increase in homeostatic functions, internalizations and an increase in physiological and behavioral flexibility. These elements are described by taking the transition from single cells to metazoans as a case study. The principle of increasing autonomy is of central relevance for understanding this transition. The hypothesis does not contradict the principle of adaptation, but rather contributes to a further understanding of its elements as it supplies aspects for a reconsideration of the relationship between the outside and the inside, between organism and environment.     

The ontogenetic origins of mirror neurons: evidence from 'tool-use' and 'audiovisual' mirror neurons

Since their discovery, mirror neurons-units in the macaque brain that discharge both during action observation and execution-have attracted considerable interest. Whether mirror neurons are an innate endowment or acquire their sensorimotor matching properties ontogenetically has been the subject of intense debate. It is widely believed that these units are an innate trait; that we are born with a set of mature mirror neurons because their matching properties conveyed upon our ancestors an evolutionary advantage. However, an alternative view is that mirror neurons acquire their matching properties during ontogeny, through correlated experience of observing and performing actions. The present article re-examines frequently overlooked neurophysiological reports of 'tool-use' and 'audiovisual' mirror neurons within the context of this debate. It is argued that these findings represent compelling evidence that mirror neurons are a product of sensorimotor experience, and not an innate endowment.     

Multiallelic selection polymorphism

The existence and stability of an internal (i.e., completely polymorphic) equilibrium for viability selection at a single multiallelic locus is investigated. Generations are discrete and nonoverlapping; the population is panmictic, monoecious, and diploid. Various necessary and sufficient conditions for the existence of an internal equilibrium are established and applied to the loss of alleles. Some necessary conditions for the existence of an asymptotically stable internal equilibrium are also established. All these conditions are simpler and yield general biological conclusions more easily than the classical necessary and sufficient conditions.     

Exclusion probabilities obtainable by biochemical polymorphisms in dogs

General formulae are given to calculate the exclusion probabilities in false paternity and parentage cases by means of gene loci with an arbitrary number of alleles whereas in paternity cases an arbitrary number of offspring per litter is considered additionally.
By aid of these formulae and on the basis of the allele frequencies of four blood protein and enzyme systems the probabilities of excluding incorrect paternity and parentage are calculated in seven German dog breeds. The results are tabulated and discussed.
It can be shown that the exclusion probability in false paternity cases increases distinctly with an increasing number of offspring per litter and its maximum is nearly attained if 5 offspring are examined. Therefore it is of value to consider entire litters in paternity controls in dogs.     

Antigen delivery to mucosa-associated lymphoid tissues using liposomes as a carrier

Oral vaccination requires an antigen delivery vehicle to protect the antigen and to enhance translocation of the antigen to the mucosa-associated lymphoid tissue. A variety of antigen delivery vehicles including liposomes have been studied for mucosal immunization. The advantages of liposome formulations are their particulate form and the ability to accommodate immunomodulators and targeting molecules in the same package. Many conventional liposomes are variably unstable in acids, pancreatic juice and bile. Nevertheless, carefully designed liposomes have demonstrated an impressive efficacy in inducing mucosal IgA responses, compared to free antigens and other delivery vehicles. However, liposomes as an oral vaccine vehicle are not yet optimized. To design liposomes that are stable in the harsh intestinal environment and are efficiently taken up by the M cells remains a challenge. This review summarizes recent research efforts using liposomes as an antigen carrier for oral vaccines with practical attention to liposome designs and interaction with the M cells.     

beta-Glucosidases as detonators of plant chemical defense

Some plant secondary metabolites are classified as phytoanticipins. When plant tissue in which they are present is disrupted, the phytoanticipins are bio-activated by the action of beta-glucosidases. These binary systems--two sets of components that when separated are relatively inert--provide plants with an immediate chemical defense against protruding herbivores and pathogens. This review provides an update on our knowledge of the beta-glucosidases involved in activation of the four major classes of phytoanticipins: cyanogenic glucosides, benzoxazinoid glucosides, avenacosides and glucosinolates. New aspects of the role of specific proteins that either control oligomerization of the beta-glucosidases or modulate their product specificity are discussed in an evolutionary perspective.     

Systematic and validated techniques for the detection of ovarian cancer emphasizing the electro-analytical approach

Ovarian cancer refers to a cancer that forms inside or on the surface of an ovary. It results in the abnormal growth of cells that can attack or spread to other parts of the body. According to the reports, early detection can minimize the risk of mortality and can lead to effective management of the disease. Though, recently used methods can only enable to detect the cancer at an advanced stage. Therefore, rapid and effective approaches for detecting ovarian cancer are urgently in demand. Researchers are fascinating towards an effective portable and early detection technique for the diagnosis of ovarian cancer. Biosensors are best alternative to afore mentioned demand as they are designed for detecting a particular biotic analyte by converting a biological entity such as antibody, blood, cell, etc. into an electronic signal that can be measured and analyzed. Biosensor technology can accommodate rapid and precise diagnosis of cancer-related cells and deliver an improved approach for making them sensitive and specific. Furthermore, choice of biomarkers also plays an important role in determining the stage of cancer. This review summarizes the classification of ovarian cancer, biomarkers and techniques employed for the detection of ovarian cancer. Besides, some of the future outlooks of bio sensing technology are also discussed.     

Peculiarities of an electric discharge between an electrolytic cathode and a metal anode

Results from experimental studies of an electric discharge operating between a solid anode and an electrolytic cathode in a wide pressure range are presented. Specific features of the discharge ignition and discharge shape and peculiarities the structure of cathode spots on the electrolyte surface and anode spots on the surface of the solid electrode are revealed. The dependences of the current density on the electrolytic cathode and metal anode on the total current are measured, and the spatial distribution of the electric field is determined. A transition of a glow discharge into a multichannel discharge is investigated. The experimental data on the frequency and amplitude of the current and voltage pulsations are presented. Requirements for the maintenance of an electric discharge with an electrolytic cathode are formulated using the obtained experimental results.     

Ecological studies on ectomycorrhizal fungi: an introduction

Abstract

The characteristics of mycorrhizal associations in general and of different kinds of mycorrhizas are briefly indicated. The morphology, functional relationships, distribution, host specifity, succession and decline of ectomycorrhizas are concisely treated. Methods, advantages and limitations of four main approaches to ectomycorrhizal research are discussed. At the end an example of an attempt to an integrated approach is given.     

Nonlinear theory of ion-acoustic waves in an ideal plasma with degenerate electrons

A nonlinear theory is constructed that describes steady-state ion-acoustic waves in an ideal plasma in which the electron component is a degenerate Fermi gas and the ion component is a classical gas. The parameter ranges in which such a plasma can exist are determined, and dispersion relations for ion-acoustic waves are obtained that make it possible to find the linear ion-acoustic velocity. Analytic gas-dynamic models of ion sound are developed for a plasma with the ion component as a cold, an isothermal, or an adiabatic gas, and moreover, the solutions to the equations of all the models are brought to a quadrature form. Profiles of a subsonic periodic and a supersonic solitary wave are calculated, and the upper critical Mach numbers of a solitary wave are determined. For a plasma with cold ions, the critical Mach number is expressed by an explicit exact formula.     

Molecular signaling involved in regulating feeding and other mitivated behaviors

The metabolic and nutritional status of an organism influences multiple behaviors in addition to food intake. When an organism is hungry, it employs behaviors that help it locate and ingest food while suppressing behaviors that are not associated with this goal. Alternatively, when an organism is satiated, food-seeking behaviors are repressed so that the animal can direct itself to other goal-oriented tasks such as reproductive behaviors. Studies in both vertebrate and invertebrate model systems have revealed that food-deprived and -satiated behaviors are differentially executed and integrated via common molecular signaling mechanisms. This article discusses cellular and molecular mechanisms for how insulin, neuropeptide Y (NPY), and serotonin utilize common signaling pathways to integrate feeding and metabolic state with other motivated behaviors. Insulin, NPY, and serotonin are three of the most well-studied molecules implicated in regulating such behaviors. Overall, insulin signaling allows an organism to coordinate proper behavioral output with changes in metabolism, NPY activates behaviors required for locating and ingesting food, and serotonin modulates behaviors performed when an organism is satiated. These three molecules work to ensure that the proper behaviors are executed in response to the feeding state of an organism. These authors contributed equally to this work.     

Product-Oriented Environmental Management: Lessons from Total Quality Management

Environmental management issues are becoming ever more prominent in business, and their focus is broadening from process orientation toward product orientation. Until now, little attention has been paid to an organizational focus on the environmental performance of products. This article therefore considers product-oriented environmental management (POEM), an approach to organizing and operating a firm in such a way that improving the environmental performance of its products and processes becomes an integrated part of operations and strategy. First, the POEM concept is introduced. Because this concept addresses some issues similar to those of quality management, the possibilities of using insights from total quality management (TQM) in developing POEM are investigated. Based on an overview of the literature and conceptual studies of TQM, a coherent set of several elements are described that can contribute to the organization of POEM. These elements are grouped in a framework, the POEM matrix, which can be used to guide research within this emerging area of organizing for the environmental characteristics of products. This matrix could also provide guidance to practitioners by delivering an integrated perspective on the organizational elements that are conducive to organizing POEM. An example from case study research in the chemical industry illustrates such an application of the matrix.     

The relationship of post-stimulus time and interval histograms to the timming characteristics of spike trains.

PST (post-stimulus time) and interval histograms computed from recorded spike trains are related to an average timing characteristics of the spike train. The exact nature of this relationship varies with recording parameters, interfering signals, the histogram bin width, and the duration of the measurement interval. This work describes the conditions under which a PST histogram can serve as an unbiased estimate of the ensemble average of a spike train's intensity and an interval histogram can serve as an unbiased estimate of the probability density function of the interspike intervals. Simulation studies are used to confirm the validity of the theoretical results. As an example of an application, these results are used to analyze recordings of singleunit activity in the eight cranial nerve.     

Tests for an Epidemic Change in a Sequence of Exponentially Distributed Random Variables

Consider a sequence of independent exponential random variables that is susceptible to a change in the means. We would like to test whether the means have been subjected to an epidemic change after an unknown point, for an unknown duration in the sequence. The likelihood ratio statistic and a likelihood ratio type statistic are derived. The distribution theories and related properties of the test statistics are discussed. Percentage points and powers of the tests are tabulated for selected values of the parameters. The powers of these two tests are then compared to the two statistics proposed by Aly and Bouzar. The tests are applied to find epidemic changes in the set of Stanford heart transplant data and air traffic arrival data.     

The spatial spread and final size of the deterministic non-reducible n-type epidemic

A model has been formulated in [6] to describe the spatial spread of an epidemic involving n types of individual, and the possible wave solutions at different speeds were investigated. The final size and pandemic theorems are now established for such an epidemic. The results are relevant to the measles, host-vector, carrier-borne epidemics, rabies and diseases involving an intermediate host. Diseases in which some of the population is vaccinated, and models that divide the population into several strata are also covered.