刨煤机平面振动的数学建模与仿真

为了降低刨头的振动,提高刨煤机的工作性能,通过简化和假设,应用牛顿定律建立了刨煤机在垂直煤壁方向振动和在水平面扭转振动的数学模型,通过对刨煤机的实体模型进行简化并导入Adams软件,得到了刨头沿垂直煤壁方向和平面扭转振动的仿真曲线,为研究刨煤机的振动、改进设计、合理确定刨煤机的参数提供了理论依据。     

Outline of a dynamical inferential conception of the application of mathematics

We outline a framework for analyzing episodes from the history of science in which the application of mathematics plays a constitutive role in the conceptual development of empirical sciences. Our starting point is the inferential conception of the application of mathematics, recently advanced by Bueno and Colyvan (2011). We identify and discuss some systematic problems of this approach. We propose refinements of the inferential conception based on theoretical considerations and on the basis of a historical case study. We demonstrate the usefulness of the refined, dynamical inferential conception using the well-researched example of the genesis of general relativity. Specifically, we look at the collaboration of the physicist Einstein and the mathematician Grossmann in the years 1912–1913, which resulted in the jointly published “Outline of a Generalized Theory of Relativity and a Theory of Gravitation,” a precursor theory of the final theory of general relativity. In this episode, independently developed mathematical theories, the theory of differential invariants and the absolute differential calculus, were applied in the process of finding a relativistic theory of gravitation. The dynamical inferential conception not only provides a natural framework to describe and analyze this episode, but it also generates new questions and insights. We comment on the mathematical tradition on which Grossmann drew, and on his own contributions to mathematical theorizing. The dynamical inferential conception allows us to identify both the role of heuristics and of mathematical resources as well as the systematic role of problems and mistakes in the reconstruction of episodes of conceptual innovation and theory change.     

A semi-automatic computerized analysis of tracks of ciliates

Summary The behavior of Protozoa can be studied by using the ethogram as a conceptual tool capable of giving an almost complete picture of the motor biology of these microorganisms. A new semi-automatic, computerized method for drawing ethograms is described here: it allows a time-saving of about 70%, in comparison with the similar manual procedure. Microorganism movements are photographed by a Pentax LX camera from the screen of a TV monitor, connected to the stereomicroscope by a TV camera, and resolved into single images using a stroboscopic apparatus. The pictorial data are introduced into the computer by means of a digitizing tablet, and the track analysis is performed semi-automatically. The measurements recorded are then processed using a commercial statistics package in order to obtain a general view of the quantitative parameters of each ethogram.     

Decomposition of almost Poisson structure of non-self-adjoint dynamical systems

Non-self-adjoint dynamical systems,e.g.,nonholonomic systems,can admit an almost Poisson structure,which is formulated by a kind of Poisson bracket satisfying the usual properties except for the Jacobi identity.A general theory of the almost Poisson structure is investigated based on a decomposition of the bracket into a sum of a Poisson one and an almost Poisson one.The corresponding relation between Poisson structure and symplectic structure is proved,making use of Jacobiizer and symplecticizer.Based on a...     

Maimon's criticism of Kant's doctrine of mathematical cognition and the possibility of metaphysics as a science

The aim of this paper is to discuss Maimon's criticism of Kant's doctrine of mathematical cognition. In particular, we will focus on the consequences of this criticism for the problem of the possibility of metaphysics as a science. Maimon criticizes Kant's explanation of the synthetic a priori character of mathematics and develops a philosophical interpretation of differential calculus according to which mathematics and metaphysics become deeply interwoven. Maimon establishes a parallelism between two relationships: on the one hand, the mathematical relationship between the integral and the differential and on the other, the metaphysical relationship between the sensible and the supersensible. Such a parallelism will be the clue to the Maimonian solution to the Kantian problem of the possibility of metaphysics as a science.     

The use of liposomes in the investigation of mechanisms of asbestos damage

Asbestos-induced cell damage is initiated by a reaction at the plasma membrane. The effect of chrysotile (which is more hemolytic and releases more silicic acid than other types of asbestos) on permeability changes of liposomes has been investigated. The destabilizing effect rises when the amount of chrysotile is increased. Silicon dioxide is one major constituent which could be a hemolytic agent, and a cause of damage. It also caused an increase of permeability of liposomes.     

Misuses of biology in the context of the paranormal

Public suspicion of science stems from science's challenging of perceptions and myths about reality, and a public fear of new technology. The result is a susceptibility to pseudoscience. In claiming that creation 'science' is as valid as evolution the creationists misquote scientists and seek to spread their own 'scientific' myths concerning a young age for the earth, an act of creation based on a particular literalist interpretation of the Christian Bible and a single worldwide flood. They use methods of debate and politics, rather than scientific research. A selection of their arguments is examined and the nature of the evidence for evolution is discussed. Problems with the creation 'science' model are noted. In the myth of the hundredth monkey phenomenon, original research is misquoted to denigrate scientific research and support sentimental ideas of paranormal events. The misuse of science is seen as damaging to society because it reduces the effective gathering and application of scientific information. However, pseudoscience provides a valuable guide to gaps in public scientific education.     

The hypothesis of the genetic transmission (autosomal recessive) of subtypes of HBs Ag. The example of Kel Kummer]

In a study of asymtomatic carriers of hepatitis B surface antigen (HBs Ag) in a closed population, the Twareg Kel Kummer, 18% of the population (79 individuals out of 439 tested) were found to be carriers of one of the 3 sub types: HBs Ag/a2 1 dw, HBs Ag/a2 1 yw and HBs Ag/a3 yw. Evidence from genealogies and the distribution of carriers in the pyramid of ages strongly supports the hypothesis of genetic transmission of the gene sub type as an autosomal recessive.     

Karyotypes of shrews of the generaCryptotis andBlarina (mammalia: Soricidae)

Summary Cryptotis parva has a diploid number of 52 and a fundamental number of 50. Blarina brevicauda in Nebraska and Pennsylvania has a diploid number of 49 or 50 and a fundamental number of 48. Blarina carolinensis in Nebraska and Kansas has a diploid number of 52 and a fundamental number of 62. The X-chromosome in all 3 species is a large metacentric chromosome. The Y-chromosome is a small acrocentric in Blarina, whereas in Cryptotis it is a small subtelocentric.Funds for field work were provided by the American Philosophical Society from the Johnson Fund. We thank Dr Robert J. Baker, Texas Tech University, for use of his karyological equipment and laboratory facilities.     

The growth of mathematical knowledge—Introduction of convex bodies

The article addresses the topic of the growth of mathematical knowledge with a special focus on the question: How are mathematical objects introduced to mathematical practice? It takes as starting point a proposal made in a previous paper which is based on a case study on the introduction of Riemann surfaces. The claim is that (i) a new object first refers to previously accepted objects, and that (ii) reasoning is possible via a correspondence to the objects with reference to which it is introduced. In addition Riemann surfaces are geometrical objects, i.e., they are placed in a geometrical context, which makes new definitions possible. This proposal is tested on a case study on Minkowski’s introduction of convex bodies. The conclusion is that the proposal holds also for this example. In both cases we notice that in a first stage is a close connection between the new object and the objects it is introduced with reference to, and that in a later stage, the new object is given an independent definition. Even though the two cases display similarity in these respects, we also point to certain differences between the cases in the process of the first stage. Overall we notice the fruitfulness of representing problems in different contexts.     

Mathematical models of regulatory mechanisms of sleep-wake rhythms

Studies of regulatory mechanisms of sleep-wake rhythms have benefited greatly from mathematical modeling. There are two major frameworks of modeling: one integrates homeostatic and circadian regulations and the other consists of multiple interacting oscillators. In this article, model constructions based on these respective frameworks and their characteristics are reviewed. The two-process model and the multioscillator model are explained in detail. An appropriate mathematical abstraction is also shown to provide a viewpoint unifying the model structures, which might seem to be distinct. Recently acquired knowledge of neural regulatory mechanisms of sleep-wake rhythm has prompted modeling at the neural network level. Such a detailed model is also reviewed, and could be used to explore a possible neural mechanism underlying a pathological state of sleep-wake rhythm.     

Implication of GABA in the spatial organization of the receptive fields of retinal ganglia cells of frogs]

An histoautoradiographic study of the Chicken and Frog retinae was made following an intravitreal injection if tritiated GABA. This amino acid was especially fixed at the amacrine and horizontal cell level. It has been suggested (Werblin, 1974) that horizontal cells might be responsible for the spatial organization of the receptive fields of retinal ganglion cells. GABA could thus be involved in bringing about of the centre-surround arrangement of the latter receptive fields. We have shown that picrotoxin, a specific GABA-antagonist, does indeed provoke marked changes in the activity of retinal ganglion cells. It provokes a decrease in the response threshold, a facilitation of spontaneous activities, and a marked increase in the receptive field area of the ON-OFF ganglion cells: from 12 at the start, it reaches 24 under the effect of picrotoxin.     

Suppressive effects of graft versus host reaction on humoral immunity: consequences of homograft of chicken spleen on differentiation of the bursa of Fabricius

By engrafting the chorio-allanto?s of Chick embryos with spleen fragments from homologous adult donors, one elicits a graft-versus-host disease. When the graft is performed before the bursa of Fabricius has reached the lymphoid differentiation state, the final follicular organization is greatly reduced. It seems that this suppression effect cannot be related to a diminution of the stem cell compartment available in the anlage but is a result of a direct impact on the mesenchyme and/or the epithelium of the bursa.     

Oxygen consumption of hibernating worker ants Dolichoderus quadripunctatus as a function of temperature and level of population]

The oxygen consumption of "hibernating" ants shows a grouping effect translated by a significant decrease in the level of oxygen consumption as a function of grouping effect. The general relation between oxygen consumption and the living body mass is the same, if the living material belongs to a single animal, or a social community of ants.     

Variations of testosterone uptake by gonadotropic cells of the adenohypophysis of the rat

Testosterone (T) could be detected by immunocytochemistry after cryoultramicrotomy and T is likely bound on a binding site of a high affinity. Castration and adrenalectomy involve a swift disappearance of T in the gonadotropic cells. Synthesis of new binding sites was induced by daily T injection in the castrated and surrenalectomized Rat from 90 days. This synthesis is inhibited by cycloheximide. These data suggest that binding sites are proteins. The captation of T by the gonadotropic cells was diminished similarly at the diminution of T, afterwards, T captation was stabilized at a weak level which became stable for several weeks. It seems that immunocytochemistry permits the study of the variation of T captation by Rat pituitary gonadotropic cells.     

Sexual responses of female canaries at the onset of song stimuli

The salience of a short conspecific song phrase versus a long one or a short heterospecific song phrase was tested in females of the common domesticated canary (Serinus canaria). All phrases were computer-edited. The copulation solicitation displays (CSD) served as an index of female responses. The results support the hypothesis that female canaries are able at the onset of a song phrase stimulus: 1) to respond to a conspecific one by displaying high levels of CSD and 2) to discriminate a conspecific from a heterospecific one. Proximal explanations examine the link between perceptual processes and phonology in the canary. Functional explanations investigate the relations between female responsiveness and the process of pair formation.     

A comparative study of the effects of muscimol and diazepam on the recall of noxious events

Muscimol induced in rats a recall deficit which possibly results from a dissociation of learning. In one out of the 2 experimental conditions studied, a cross dissociation of learning was found between diazepam and muscimol.     

Specificity of action of phospholipases of rat intestinal mucosa]

The total homogenate of rat intestine is devoid of C or D phospholipase activity. At pH 6,5 in the presence of phosphatidylcholines, it exhibits a B phospholipase activity and in the presence of exogen lysophosphatidylcholines an A1 lysophospholipase activity. At pH 8,5 the intestinal mucous membrane of a rat shows an isolated A2 phospholipase activity.     

The stoichiometry of peptide-heparan sulfate binding as a determinant of uptake efficiency of cell-penetrating peptides

Binding to negatively charged heparan sulfates (HS) at the cell surface is considered the first step in the internalization of cationic cell-penetrating peptides (CPPs). However, little is known about the relation of the characteristics of the HS-CPP interaction such as affinity, stoichiometry, and clustering with uptake. In this study, we investigated a collection of mutants of a cyclic CPP derived from human lactoferrin with respect to HS binding and uptake. The thermodynamic parameters of HS binding were determined by isothermal titration calorimetry, clustering of HS was investigated by dynamic light scattering, and cellular uptake by flow cytometry and confocal microscopy. Whereas mutations of non-arginine amino acids that are conserved across lactoferrins of different mammalia only had a minor effect on uptake efficiency, changes in the number of arginine residues influenced the uptake significantly. In general, introduction of arginine residues and cyclization improved the HS affinity and the ability to cluster HS. In particular, there was a strong negative correlation between stoichiometry and uptake, indicating that crosslinking of HS is the driving force for the uptake of arginine-rich CPPs. Using glycan microarrays presenting a collection of synthetic HS, we show that a minimal chain length of HS is required for peptide binding.     

A simple check of the time homogeneity of Markov chains

In this paper we consider a population where the state of each individual follows a Markov chain. If the population is recorded for a very few periods only, it is still possible to estimate the transition matrix and to make projections into the far future. These forecasts are sensible if the chains are time homogeneous, but this is difficult to check if only a few periods are observed. We suggest a simple method to check this assumption, and obtain an upper bound on the time the process can have been time homogeneous. The method is also applied to a second-order Markov chain and to the mover-stayer model. AMS subject classification (1980): Primary 62M05, Secondary 62M20.