A genetical model for vitiligo.

A genetical model is found to provide a good fit to family data on vitiligo. The model postulates that recessive alleles at a set of four unlinked diallelic loci are involved in the causation of the disorder. Under this multiple recessive homozygosis model, for normal X affected families ascertained through the affected parent, the expected segregation probability is .063; the estimated value is 0.53, which is not significantly different from the expected value. For normal X normal families ascertained through an affected offspring, the expected segregation probability is .037; the estimated value is .04.     

A population genetical model for sequence evolution under multiple types of mutation

DNA sequencing and restriction mapping provide us with information on DNA sequence evolution within populations, from which the phylogenetic relationships among the sequences can be inferred. Mutations such as base substitutions, deletions, insertions and transposable element insertions can be identified in each sequence. Theoretical study of this type of sequence evolution has been initiated recently. In this paper, population genetical models for sequence evolution under multiple types of mutation are developed. Models of infinite population size with neutral mutation, infinite population size with deleterious mutation and finite population size with neutral mutation are considered.     

A Tentative Cultural Sequence for the Snyder Site,Kansas

Abstract

Prior to the past decade documentation for the Archaic period in Kansas has not been substantial. One reason evidence has been slow in emerging is the discovery that Archaic sites are often buried under several feet of overburden, maKing their detection difficult. The Snyder site (14BU9), north of ElDorado in Butler County, Kansas, is such a site. Four tentative phases are defined: Butler, Walnut, El Dorado, and Chelsea.     

A non-linear model for the synaptic basis of neuronal memory.

We propose a mathematical model for the synaptic basis of neuronal memory. The model incorporates non-linear effects in analogy with population growth problems of human beings, animals, biological species, crystal growth, etc., and provides a mechanism whereby the excitatory and inhibitory inputs produce alterations in a neurone which result in a long-lasting increase in transmitter release at a synapse.     

Trends in suicide and unemployment in Scotland, 1976-86.

To establish whether a correlation exists between unemployment and suicide the trends in the rates of both among men in Scotland during 1976-86 were studied. Both rates showed rapid increases in the late 1970s and then much slower increases after 1982. In contrast, among women, although the rate of unemployment followed a similar pattern, there was a gradual fall in the rate of suicide. The trends in regional unemployment for men during 1971-81 were compared with the suicide rates for the period before the increase (1974-7) and the period after the rapid increase (1983-6). No association was observed between trends in suicide and unemployment when analysed by health board areas or aggregates of local government districts. These data do not support the hypothesis that the rise in unemployment is a direct cause of the rise in suicide rates among men.     

Abortion in South Australia, 1971-86: an update

Official statistics on abortion in South Australia for the period 1971-86 are analysed in terms of incidence, age of patients and nuptiality, reasons for abortion, method of termination, period of gestation, previous abortions and concurrent sterilisation. Demographic implications are discussed and recommendations are made for more education and counselling, especially for younger and unmarried women for whom the incidence of abortion seems to be rising.     

Qxpak: a versatile mixed model application for genetical genomics and QTL analyses

MOTIVATION: Current methodology and software for quantitative trait loci (QTL) analyses do not use all available information and are inadequate to deal with the huge amount of QTL analyses to be needed in forecoming genetical genomics' studies. RESULTS: We show that a mixed model statistical framework provides a very flexible tool for QTL modeling in a variety of populations, be it a cross between inbred lines, a within population study, or experiments involving a mixture of populations or crosses. The software allows multitrait and multiQTL analyses, inclusion of infinitesimal genetic value and a batch multitrait option suitable for genetical genomics studies. It also allows massive association studies between single nucleotide polymorphisms and the trait(s) of interest. AVAILABILITY: A software (Qxpak), together with a manual and example files, is freely available for research purposes. So far, the compiled program is available for linux systems, the windows version will follow soon. See http://www.icrea.es/pag.asp?id=Miguel.Perez     

A holographic model for associative memory chains

Holographic brain models are well suited to describe specific brain functions. Central nervous systems and holographic systems both show parallel information processing and non-localized storage in common. To process information both systems use correlation functions suggesting to develop cybernetical brain models in terms of holography. Associative holographic storage is done with two simultaneously existing patterns. They may reconstruct each other mutually. Time-sequentially existing patterns are connected to associative chains, if every two succeeding patterns do exist within a common period of time in order to be stored in pairs. Read out (recall) of associative chains—reconstructing coupled patterns which didn't exist simultaneously—requires advanced holographic techniques. Three different methods are described and tested experimentally. The underlying principles are feedback mechanisms, nonlinearities of the storage material and tridimensional architecture of the voluminous recording medium. Those principles evidently occur in neural storage systems supporting analogous information processing in neural- and holographic systems.     

A model for the speed of memory retrieval

The memory retrieval process of number problems with external noise is studied with the use of the Bonhoeffer–van der Pol oscillator model. Three cell assembly responses are simulated, coding one true number and two neighboring erroneous. The time of a correct response, T _c, was averaged over statistical assemblies of numerous trials. It is demonstrated that T _c takes a minimum value for a certain noise intensity. This result correlates well with experimental data by Usher and Feingold (2000). The location of the minimum as a function of the time delay between two consecutive simulation trials is investigated.     

By genes alone: a model selectionist argument for genetical explanations of cooperation in non-human organisms

I distinguish two versions of kin selection theory—a purely genetic version (GKST) and a version that also appeals to cultural (i.e. non-genetically-derived) forms of cooperation (WKST)—and present an argument in favor of using the former when it comes to accounting for the evolution of cooperation in non-human organisms. Specifically, I first show that both GKST and WKST are equally mathematically coherent—they can both be derived from the Price equation—but not necessarily equally empirically plausible, as they are based on different assumptions about the inheritance system underlying the cooperative phenotype. Given this, I then, second, present a model selection theoretic argument in favor of GKST over WKST. This argument is based on the fact that, in non-human cases, the former theory is likely to be as empirically successful as WKST, while containing fewer degrees of freedom. I end by defending both the intrinsic importance of this argument and its relevance to the discussion surrounding the “gene’s eye view of evolution.”     

A hierarchical neural network model for associative memory

A hierarchical neural network model with feedback interconnections, which has the function of associative memory and the ability to recognize patterns, is proposed. The model consists of a hierarchical multi-layered network to which efferent connections are added, so as to make positive feedback loops in pairs with afferent connections. The cell-layer at the initial stage of the network is the input layer which receives the stimulus input and at the same time works as an output layer for associative recall. The deepest layer is the output layer for pattern-recognition. Pattern-recognition is performed hierarchically by integrating information by converging afferent paths in the network. For the purpose of associative recall, the integrated information is again distributed to lower-order cells by diverging efferent paths. These two operations progress simultaneously in the network. If a fragment of a training pattern is presented to the network which has completed its self-organization, the entire pattern will gradually be recalled in the initial layer. If a stimulus consisting of a number of training patterns superposed is presented, one pattern gradually becomes predominant in the recalled output after competition between the patterns, and the others disappear. At about the same time when the recalled pattern reaches a steady state in he initial layer, in the deepest layer of the network, a response is elicited from the cell corresponding to the category of the finally-recalled pattern. Once a steady state has been reached, the response of the network is automatically extinguished by inhibitory signals from a steadiness-detecting cell. If the same stimulus is still presented after inhibition, a response for another pattern, formerly suppressed, will now appear, because the cells of the network have adaptation characteristics which makes the same response unlikely to recur. Since inhibition occurs repeatedly, the superposed input patterns are recalled one by one in turn.