A simplified mercury switch head-control biofeedback device

A simplified mercury switch head-control device is reported. It is easily duplicated and amenable to quantitation. Advantages include simplicity and easy use at home, in school, or during therapy. Directionality of the feedback signal and visual feedback do not seem necessary to produce benefit. The results in six patients and two controls are consistent with other studies. This is the second study using mercury switches for feedback.This study was supported in part by BRSG Grant RR-0537 awarded by the Biomedical Research Support Grant Program, Division of Research Resources, NIH.     

Global dynamics of a selection model for the growth of a population with genotypic fertility differences

A population growth model is considered for a one locus two allele problem with selection based entirely on fertility differences. A local stability analysis is carried out for the critical points — which include possible polymorphic states — of the resulting nonlinear differential equations. The methods of dynamical systems theory are applied to obtain limiting genotypic proportions for every initial state. Thus the results are global and there are no periodic solutions.Research for this paper was partially supported by the National Science and Engineering Research Council of Canada Grant NSERC A-8130Research for this paper was partially supported by the National Science and Engineering Research Council of Canada Grant NSERC A-4823Research supported by NSF Grant MCS 7901069. A portion of the work was carried out while the author was a Visiting Professor at the University of Utah, Salt Lake City, Utah     

Evolutionary games for spatially dispersed populations

An evolutionary game model is developed that incorporates both spatial dispersion and density effects in the evolutionary dynamic. It is shown that a stable equilibrium (e.g. an evolutionarily stable strategy) of the non-dispersed frequency dynamic becomes a stable equilibrium of the larger system if population density stabilizes at these fixed frequencies. It is also shown, by example, that other equilibria, whose frequencies change from one location to another, may appear when dispersal rates are relatively small.Research supported by Natural Sciences and Engineering Research Council of Canada Operating Grant A6187Research supported by Natural Sciences and Engineering Research Council of Canada Operating Grant A7822     

Evoked potentials in artificial neural nets

A neural net model of discrete populations of formal neurons have been constructed to study evoked potentials based on our previous simulation studies (Anninos, 1972). Some interesting results came up from the examination of our findings regarding the latencies and the period of the cyclic activity of the evoked potentials. In fact, the different successive latencies for the five identical stimuli and the different periods for each of the cyclic activities, all are consequences of inhibitory and excitatory influences from a large neuronal population. Furthermore, such behavior of the system is not only related to the unknown neuronal population but was also substantially altered by what occurred in other systems at the time of stimulus, or prior to it.Computation assistance was provided by the Health Sciences Computing Facility, UCLA, sponsored by NIH Special Research Resources Grant RR-3. Research was sponsored by NSF Grant GB 30498 and NIH Grant NS-8498.     

Chemical models of oxidative phosphorylation

Chemical models for coupling oxidation to phosphorylation are summarized and examined both from the standpoint of organic reaction mechanisms and with respect to their relevance to mitochondria and chloroplasts. In order to accelerate the progress of our research in bioenergetics, it is suggested to focus at least as much attention on structural biochemistry as on phenomenological observations of energy-transducing membranes.Supported in part by Public Health Service Research Grant No. GM 19990 from the National Institute of General Medical Sciences and by National Science Foundation Research Grant No. PCM 74-24083 A01     

Socio-bioenergetics and sexual dimorphism in primates

Socio-bioenergetics is presented as a practical method of estimating energy budgets of primates in a social context. Energy budgets are estimated on the basis of behavioral observations and a series of empirical formulae, which consider body weight, activity, and reproductive status. Data on a captive colony of Sykes' monkeys and baboons are incorporated as illustrations of the possible effects of group composition, body size, reproductive status, and activity patterns on energy requirements.Supported by the Wenner-Gren Foundation for Anthropological Research Incorporated and the National Science Foundation Grant GU-1598.     

Common source epidemics I: A stochastic model

A discrete time stochastic model is formulated for the spread of a disease which is transmitted to an uninfected but susceptible individual through an environmental source and not through contact (either direct or indirect) with infected individuals. The model incorporates both exposure and infection components. The exposure component includes consideration of the introduction of an infectious agent into the environment and the subsequent diffusion of the agent. It also includes time and location patterns for visits by individuals in the target population to the affected environment. The infection component incorporates physiological responses of exposed individuals to the infectious agent. The goal of the model is to provide a method for developing a predicted epidemic curve. Comments are given on an application of the model to the study of an outbreak of toxoplasmosis in Atlanta, Georgia, in 1977. This work was partially supported by BRSG Grant S07 RR0731 awarded by the Biomedical Research Support Grant Program, Division of Research Resources, National Institutes of Health.     

Macaca radiata: Intragroup relations and reproductive status of females

A 21-day study of captive bonnet macaques at the California Primate Research Center during the 1973 birth season showed that females with new infants are spaced significantly closer to a central adult male than are pregnant females. This research was supported by Grant #RR00169 from the National Institutes of Health.     

Direct connections between mitochondria and catecholamine-storage vesicles demonstrated by high voltage electron microscopy in rat adrenal medulla

Summary Tubular channels from mitochondria to catecholamine-storage vesicles have been demonstrated in thick sections of adrenal medullary tissue from hypoglycemia-stressed rats by the use of the high voltage electron microscope. The function of these connections is not presently known although they may serve as channels for the transport of materials such as high-energy nucleotides from one organelle to the other. The present study has examined only the adrenal medulla, but it should be considered that such connections may also exist in other neural cells and possibly other cells in which there is intracellular transport of ATP.This work was supported by NIH DRR 70-4136, WVU Medical Corporation Research Grants, Biomedical Research Support Grant 5 SOI RR05433, WVU Senate Research Grant, and West Virginia Heart Association Research Grant. We wish to thank Barbara Coalgate, Billie Pack, and the staffs of the HVEM laboratories at U.S. Steel and University of Colorado.     

Stochastic models for subpopulation emergence in heterogeneous tumors

A stochastic analog to a deterministic model describing subpopulation emergence in heterogeneous tumors is developed. The resulting system is described by the Fokker-Planck or forward Kolmogorov equation. A finite element approach for the numerical solution to this equation is described. Four biological and clinical scenarios are simulated (emergence of heterogeneity, exclusion of a subpopulation, and induction of drug resistance in both pure and heterogeneous tumors). The results of the simulations show that the stochastic model describes the same basic dynamics as its deterministic counterpart via a convective component, but that for each simulation a distribution of tumor sizes and mixes can also be derived from a diffusive component in the model. These distributions yield estimates for subpopulation extinction probabilities. The biological and clinical relevance of these results are discussed. Research support provided in part by ACS Grant IN45-Z and ACS PDT 243 B. Research support provided in part by the National Science Foundation under NSF Grant MCS-8504316, and by the Air Force Office of Scientific Research under Contract F49620-86-C-0111.     

Interspecies transmission and host restriction of avian H5N1 influenza virus

Long-term endemicity of avian H5N1 influenza virus in poultry and continuous sporadic human infections in several countries has raised the concern of another potential pandemic influenza. Suspicion of the avian origin of the previous pandemics results in the close investigation of the mechanism of interspecies transmission. Entry and fusion is the first step for the H5N1 influenza virus to get into the host cells affecting the host ranges. Therefore receptor usage study has been a major focus for the last few years. We now know the difference of the sialic acid structures and distributions in different species, even in the different parts of the same host. Many host factors interacting with the influenza virus component proteins have been identified and their role in the host range expansion and interspecies transmission is under detailed scrutiny. Here we review current progress in the receptor usage and host factors. Supported by the National Basic Research Program of China (Grant Nos. 2005CB523001, 2005CB523002), National Key Technologies Research & Development Program (Grant 2006BAD06A01/2006BAD06A04); US National Institutes of Health (NIH) (Grant 3 U19 AI051915-05S1), the National Natural Science Foundation of China (Grant 30599434). GAO FG is a distinguished young investigator of the NSFC (Grant No. 30525010).     

Unilateral agenesis of the diaphragm

Summary A brother and sister with congenital agenesis of the diaphragm are described and the literature reviewed with respect to the familial incidence of congenital diaphragmatic lesions. Although unilateral agenesis of the diaphragm is infrequent, four comparable reports of familial occurrence were found.Based on anatomic and genetic considerations, the hypothesis is advanced that agenesis of the diaphragm may be etiologically different from other lesions of the diaphragm. The possibility exists that a rare recessive gene in some cases might cause this developmental failure of the diaphragm anlage.This investigation was supported in part by USPHS International Postdoctoral Research Fellowship Grant No. FO 5-TW-1129, and by Public Health Service Research Grant No. HD-00635-04, from the National Institute of Child Health and Human Development.     

Do numerical polymorphisms exist at the human 5 S locus?

Summary Grain count analysis following hybridization in situ was used to determine whether there are numerical polymorphisms, at the human genes that code for 5S RNA. Of seven individuals surveyed in this study, two showed significant, differences between the number of autoradiographic grains on the tips of the homologs of chromosome 1q. It is concluded that numerical polymorphisms exist at the locus that transcribes 5S RNA in some individuals.Supported by Contract DOE no. EY-76-S-02-3133, NIH Grant GM 21833, American Cancer Society Grant NP-247, and a grant from the National Foundation-march of Dimes. A.S.H. is the recipient of Research Career Development Award K4-GM 00017.     

A new traveling-wave solution of Fisher's equation with density-dependent diffusivity

A new traveling-wave solution of Fisher's equation is found when the diffusivity is taken to be a smoothed step function of the dependent variable. The form of the solution and a necessary relationship between the traveling wave's speed and the diffusivity are predicted. This is done using flux continuity considerations in the limit when the diffusivity is piecewise constant. The predicted form is verified by numerical integration of the equation with a slightly smoothed step function diffusivity.Work performed under the auspices of the US Army Research Office (Durham), Contract DAAL03-89-K-0014; the National Science Foundation, Grant DMS87-06642; and the Air Force Office of Scientific Research, Grant AFOSR-88-0269     

Heat lability of rabbit anti-Mycoplasma pneumoniae serum

The metabolic-inhibition test utilizing glucose as a substrate was used to follow the immune response of New Zealand white rabbits injected via the footpad with a suspension ofMycoplasma pneumoniae grownin vitro. Sera were collected 7 and 11 days after initial inoculation and at intervals following several booster injections. The early sera were shown to be dependent upon a heat-labile accessory factor for demonstration of the inhibitory activity. This accessory factor could be supplied by unheated normal rabbit or normal guinea pig serum. The sera collected subsequent to multiple booster injections did not require such a heat-labile factor and inhibition was not enhanced by the addition of normal rabbit sera. A preliminary TEAE cellulose fractionation of early immune serum gave evidence for two species of antibody activities, one heat-stable dependent upon a heat-labile accessory factor for activity, and the other heat-labile dependent upon a heat-labile accessory factor for activity. Junior Research Fellow supported by USPH Training Grant 5T01 A100232 This study was supported by Public Health Service Research Grant 5 R01 A109002 and National Science Foundation Grant GB 4778. The results of this study were presented, in part, at the 1970 Annual Meetings of the American Society for Microbiology in Boston, Massachusetts.     

Diffusion-driven instability in a predator-prey system with time-varying diffusivities

We consider an ecological model by Levin and Segel (1976) for predator-prey planktonic species, which consists of two reaction-diffusion equations, and extend it to plankton populations with time-varying diffusivities. The local stability of uniform equilibria is examined both analytically and numerically. It is found that diffusive instability is less likely to occur in systems with time-varying diffusivity than those with constant diffusivity. Contribution No. 803 of the Marine Sciences Research Center, State University of New York, Stony Brook Supported by the Danish Science Research Council (Grant nos. 11-7128, 11-8321), the Danish Research Academy (Grant nos. E-880011, V-890085) and a Travel Grant for Mathematicians (Rejselegat for Matematikere) Supported by Hudson River Foundation, Grant no. 01488AO37     

The Danziger-Elmergreen theory of periodic catatonic schizophrenia

Properties of the solutions of the mathematical model introduced by Danziger and Elmergreen for the study of periodic catatonic schizophrenia are studied, and it is shown that the properties established suggest that the model can be used to study other forms of catatonic schizophrenia besides periodic catatonic schizophrenia. The research in this paper was supported by the U.S. Army Research Office (Durham) (Grant No. DA-ARO-D-31-124-G1098) and by a Rutgers Research Council Faculty Fellowship.     

Order,analogy, and efficacy in ethiopian medical divination

An important source of the efficacy of techniques for managing sickness is their capacity for symbolically ordering the disordered states associated with disease. (The ability to give empirical proofs is another source.) This article describes the symbolic ordering worked by a method of divination that is practiced by the Amhara of Ethiopia. Emphasis is given to indicating how order is accomplished through linking disease with phenomenological domains that are remote from the biophysical locus of sickness. The point is made that ordering and linking depend on processes of analogy.The field research on which this article is based was conducted from January to December 1966 and was supported by a Public Health Service Research Grant and Fellowship from the National Institute of Mental Health.     

Pólya-like urns and the Ewens' sampling formula

A Markov process of partitions of the natural numbers is constructed by defining a Pólya-like urn model. The marginal distributions of this process are the Ewens' sampling distributions of population genetics.Research supported in part by NSF Grant MCS-8108689     

Models of competition in the chemostat with instantaneous and delayed nutrient recycling

Two models for competition of two populations in a chemostat environment with nutrient recycling are considered. In the first model, the recycling is instantaneous, whereas in the second, the recycling is delayed. For each model an equilibrium analysis is carried out, and persistence criteria are obtained. This paper extends the work done by Beretta et al. (1990) for a single species.Research partially supported by the Natural Sciences and Engineering Research Council of Canada, Grant NSERC A4823Research carried out at the University of Alberta while on a Canada-China Scholarly Exchange Program