615 research outputs found
The computational complexity of Kauffman nets and the P versus NP problem
Complexity theory as practiced by physicists and computational complexity
theory as practiced by computer scientists both characterize how difficult it
is to solve complex problems. Here it is shown that the parameters of a
specific model can be adjusted so that the problem of finding its global energy
minimum is extremely sensitive to small changes in the problem statement. This
result has implications not only for studies of the physics of random systems
but may also lead to new strategies for resolving the well-known P versus NP
question in computational complexity theory.Comment: 4 pages, no figure
LâADAPTATION POSITIVE DES FAMILLES LATINOS AVEC UN ENFANT AYANT UNE DĂFICIENCE INTELLECTUELLE: UNE PREMIĂRE VUE DE LA THĂORIE DE LâADAPTATION POSITIVE
Historically, research on disability and family dynamics drew from Psychology and Medicine. Consequently, eugenics models, grief theory, and other largely decontextualized frameworks of stress and coping were used to explain families of children with disabilities. This is a report of an initial test of a set of ideas the Singer research team has combined in order to explore the cognitive and problem-solving approaches of families of children with disabilities. Our purpose is to propose a contextualized theory for explaining how cultural diversity has an impact on positive adaptation to a childâs disability. This theory addresses the following: 1) attachment; 2) internal and external cultural resistance to stigmas about disability; and 3) perceived informal (family/friends) and formal (professionals) sources of support for positive views about disability and parenting. Sampling Latino families demonstrated how cultural contexts demonstrate a different flavour from majority culture interpretations of these cognitive terms of our proposed theory. Transcripts of the interviews were coded using grounded theory analysis, specifically, the constant comparative method. We discuss the goodness of fit for themes emerging from the coding process with the proposed theory terms. Results confirm attachment, social supports, and cultural resistance as terms for future development of this proposed theory.
Keywords: Disability and parenting, positive adaptation, Latinos and disability, culture and disabilityĂ travers lâhistoire, la recherche sur les handicapĂ©s et les relations intrafamiliales utilisait comme sources la psychologie et la mĂ©dicine. Par consĂ©quent, les modĂšles de lâeugĂ©nisme, les thĂ©ories sur le deuil, et dâautres cadres analytiques sur le stress et les stratĂ©gies dâadaptation, plutĂŽt dĂ©contextualisĂ©s, Ă©taient utilisĂ©s afin dâexpliquer aux autres comment fonctionnaient les familles avec un enfant handicapĂ©. Ceci est un reportage sur un test initial dâun ensemble dâidĂ©es quâa combinĂ© lâĂ©quipe de recherche Singer afin dâaborder les approches cognitives et mĂ©thodes actives des familles des enfants handicapĂ©s. Nous proposons une thĂ©orie contextualisĂ©e afin dâexpliquer comment la diversitĂ© culturelle aurait un effet sur lâadaptation positive de la famille face Ă lâhandicap de leur enfant. Cette thĂ©orie aborde les idĂ©es suivantes : 1) lâattachement; 2) les rĂ©sistances culturelles internes et externes aux stigmates sur lâhandicap; et 3) les sources dâinformation sur lâhandicap et le parentage liĂ©es Ă lâadaptation positive perçues comme informelles (famille/amis) et formelles (les professionnels). En utilisant un Ă©chantillon de familles Latinos, nous dĂ©montrons comment les contextes culturels dĂ©montrent des interprĂ©tations diffĂ©rentes des termes cognitifs de notre thĂ©orie, et non lâinterprĂ©tation de la culture majoritaire. Les transcriptions des interviews Ă©taient codĂ©es selon la thĂ©orie ancrĂ©e, plus spĂ©cifiquement la mĂ©thode de la comparaison constante. Nous discutons la concordance des thĂšmes venus via le processus dâencodage avec les termes clĂ©s de la nouvelle thĂ©orie proposĂ©e. Les rĂ©sultats de cette recherche confirment que lâattachement, le soutien social, et la rĂ©sistance culturelle seront des termes clĂ©s dans le dĂ©veloppement de cette thĂ©orie proposĂ©e.
Mots clés : Handicap et parentage, Adaptation positive, Latinos et handicap, culture et handica
Diagnosis and control of Equine Infectious Anemia in a horse farm located in Buenos Aires province, Argentina
Inst.de VirologĂaFil: Vissani, Aldana. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de VirologĂa; ArgentinaFil: Reynal O'Connor, J. Laboratorio Equino S.R.L.; ArgentinaFil: Olguin Perglione, Cecilia. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de VirologĂa; ArgentinaFil: Traverso, S. Laboratorio Equino S.R.L.; ArgentinaFil: Gutierrez, G. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de VirologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Alvarez, Irene. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de VirologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Barrandeguy, Maria Edith. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de VirologĂa; Argentina. Universidad del Salvador. Escuela de Veterinaria; Argentin
The Asymptotic Number of Attractors in the Random Map Model
The random map model is a deterministic dynamical system in a finite phase
space with n points. The map that establishes the dynamics of the system is
constructed by randomly choosing, for every point, another one as being its
image. We derive here explicit formulas for the statistical distribution of the
number of attractors in the system. As in related results, the number of
operations involved by our formulas increases exponentially with n; therefore,
they are not directly applicable to study the behavior of systems where n is
large. However, our formulas lend themselves to derive useful asymptotic
expressions, as we show.Comment: 16 pages, 1 figure. Minor changes. To be published in Journal of
Physics A: Mathematical and Genera
Computational core and fixed-point organisation in Boolean networks
In this paper, we analyse large random Boolean networks in terms of a
constraint satisfaction problem. We first develop an algorithmic scheme which
allows to prune simple logical cascades and under-determined variables,
returning thereby the computational core of the network. Second we apply the
cavity method to analyse number and organisation of fixed points. We find in
particular a phase transition between an easy and a complex regulatory phase,
the latter one being characterised by the existence of an exponential number of
macroscopically separated fixed-point clusters. The different techniques
developed are reinterpreted as algorithms for the analysis of single Boolean
networks, and they are applied to analysis and in silico experiments on the
gene-regulatory networks of baker's yeast (saccaromices cerevisiae) and the
segment-polarity genes of the fruit-fly drosophila melanogaster.Comment: 29 pages, 18 figures, version accepted for publication in JSTA
Salivary Metabolomic Signatures and Body Mass Index in Italian Adolescents: A Pilot Study
Context: Obesity surveillance is scarce in adolescents, and little is known on whether salivary metabolomics data, emerging minimally invasive biomarkers, can characterize metabolic patterns associated with overweight or obesity in adolescents. Objective: This pilot study aims to identify the salivary molecular signatures associated with body mass index (BMI) in Italian adolescents. Methods: Saliva samples and BMI were collected in a subset of n = 74 young adolescents enrolled in the Public Health Impact of Metal Exposure study (2007-2014). A total of 217 untargeted metabolites were identified using liquid chromatography-high resolution mass spectrometry. Robust linear regression was used to cross-sectionally determine associations between metabolomic signatures and sex-specific BMI-for-age z-scores (z-BMI). Results: Nearly 35% of the adolescents (median age: 12 years; 51% females) were either obese or overweight. A higher z-BMI was observed in males compared to females (P = .02). One nucleoside (deoxyadenosine) and 2 lipids (18:0-18:2 phosphatidylcholine and dipalmitoyl-phosphoethanolamine) were negatively related to z-BMI (P < .05), whereas 2 benzenoids (3-hydroxyanthranilic acid and a phthalate metabolite) were positively associated with z-BMI (P < .05). In males, several metabolites including deoxyadenosine, as well as deoxycarnitine, hyodeoxycholic acid, N-methylglutamic acid, bisphenol P, and trigonelline were downregulated, while 3 metabolites (3-hydroxyanthranilic acid, theobromine/theophylline/paraxanthine, and alanine) were upregulated in relation to z-BMI (P < .05). In females, deoxyadenosine and dipalmitoyl-phosphoethanolamine were negatively associated with z-BMI while deoxycarnitine and a phthalate metabolite were positively associated (P < .05). A single energy-related pathway was enriched in the identified associations in females (carnitine synthesis, P = .04). Conclusion: Salivary metabolites involved in nucleotide, lipid, and energy metabolism were primarily altered in relation to BMI in adolescents
Spin and magnetization effects in plasmas
We give a short review of a number of different models for treating
magnetization effects in plasmas. In particular, the transition between kinetic
models and fluid models is discussed. We also give examples of applications of
such theories. Some future aspects are discussed.Comment: 18 pages, 1 figure. To appear in Plasma Physics and Controlled
Fusion, Special Issue for the 37th ICPP, Santiago, Chil
Prediction of lethal and synthetically lethal knock-outs in regulatory networks
The complex interactions involved in regulation of a cell's function are
captured by its interaction graph. More often than not, detailed knowledge
about enhancing or suppressive regulatory influences and cooperative effects is
lacking and merely the presence or absence of directed interactions is known.
Here we investigate to which extent such reduced information allows to forecast
the effect of a knock-out or a combination of knock-outs. Specifically we ask
in how far the lethality of eliminating nodes may be predicted by their network
centrality, such as degree and betweenness, without knowing the function of the
system. The function is taken as the ability to reproduce a fixed point under a
discrete Boolean dynamics. We investigate two types of stochastically generated
networks: fully random networks and structures grown with a mechanism of node
duplication and subsequent divergence of interactions. On all networks we find
that the out-degree is a good predictor of the lethality of a single node
knock-out. For knock-outs of node pairs, the fraction of successors shared
between the two knocked-out nodes (out-overlap) is a good predictor of
synthetic lethality. Out-degree and out-overlap are locally defined and
computationally simple centrality measures that provide a predictive power
close to the optimal predictor.Comment: published version, 10 pages, 6 figures, 2 tables; supplement at
http://www.bioinf.uni-leipzig.de/publications/supplements/11-01
Schumpeterian economic dynamics as a quantifiable minimum model of evolution
We propose a simple quantitative model of Schumpeterian economic dynamics.
New goods and services are endogenously produced through combinations of
existing goods. As soon as new goods enter the market they may compete against
already existing goods, in other words new products can have destructive
effects on existing goods. As a result of this competition mechanism existing
goods may be driven out from the market - often causing cascades of secondary
defects (Schumpeterian gales of destruction). The model leads to a generic
dynamics characterized by phases of relative economic stability followed by
phases of massive restructuring of markets - which could be interpreted as
Schumpeterian business `cycles'. Model timeseries of product diversity and
productivity reproduce several stylized facts of economics timeseries on long
timescales such as GDP or business failures, including non-Gaussian fat tailed
distributions, volatility clustering etc. The model is phrased in an open,
non-equilibrium setup which can be understood as a self organized critical
system. Its diversity dynamics can be understood by the time-varying topology
of the active production networks.Comment: 21 pages, 11 figure
Antiplasmodial and leishmanicidal activities of 2-cyano-3-(4-phenylpiperazine-1-carboxamido) quinoxaline 1,4-dioxide derivatives.
Malaria and leishmaniasis are two of the Worldâs most important tropical
parasitic diseases. Thirteen new 2-cyano-3-(4-phenylpiperazine-1-carboxamido) quinoxaline
1,4-dioxide derivatives (CPCQs) were synthesized and evaluated for their in vitro
antimalarial and antileishmanial activity against erythrocytic forms of Plasmodium
falciparum and axenic forms of Leishmania infantum. Their toxicity against VERO cells
(normal monkey kidney cells) was also assessed. None of the tested compounds was
efficient against Plasmodium, but two of them showed good activity against Leishmania.
Toxicity on VERO was correlated with leishmanicidal properties
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