901 research outputs found
No spin glass phase in ferromagnetic random-field random-temperature scalar Ginzburg-Landau model
Krzakala, Ricci-Tersenghi and Zdeborova have shown recently that the random
field Ising model with non-negative interactions and arbitrary external
magnetic field on an arbitrary lattice does not have a static spin glass phase.
In this paper we generalize the proof to a soft scalar spin version of the
Ising model: the Ginzburg-Landau model with random magnetic field and random
temperature-parameter. We do so by proving that the spin glass susceptibility
cannot diverge unless the ferromagnetic susceptibility does.Comment: 9 page
Comparative Study for Inference of Hidden Classes in Stochastic Block Models
Inference of hidden classes in stochastic block model is a classical problem
with important applications. Most commonly used methods for this problem
involve na\"{\i}ve mean field approaches or heuristic spectral methods.
Recently, belief propagation was proposed for this problem. In this
contribution we perform a comparative study between the three methods on
synthetically created networks. We show that belief propagation shows much
better performance when compared to na\"{\i}ve mean field and spectral
approaches. This applies to accuracy, computational efficiency and the tendency
to overfit the data.Comment: 8 pages, 5 figures AIGM1
The number of matchings in random graphs
We study matchings on sparse random graphs by means of the cavity method. We
first show how the method reproduces several known results about maximum and
perfect matchings in regular and Erdos-Renyi random graphs. Our main new result
is the computation of the entropy, i.e. the leading order of the logarithm of
the number of solutions, of matchings with a given size. We derive both an
algorithm to compute this entropy for an arbitrary graph with a girth that
diverges in the large size limit, and an analytic result for the entropy in
regular and Erdos-Renyi random graph ensembles.Comment: 17 pages, 6 figures, to be published in Journal of Statistical
Mechanic
Cryptochrome proteins regulate the circadian intracellular behavior and localization of PER2 in mouse suprachiasmatic nucleus neurons.
The ∼20,000 cells of the suprachiasmatic nucleus (SCN), the master circadian clock of the mammalian brain, coordinate subordinate cellular clocks across the organism, driving adaptive daily rhythms of physiology and behavior. The canonical model for SCN timekeeping pivots around transcriptional/translational feedback loops (TTFL) whereby PERIOD (PER) and CRYPTOCHROME (CRY) clock proteins associate and translocate to the nucleus to inhibit their own expression. The fundamental individual and interactive behaviors of PER and CRY in the SCN cellular environment and the mechanisms that regulate them are poorly understood. We therefore used confocal imaging to explore the behavior of endogenous PER2 in the SCN of PER2::Venus reporter mice, transduced with viral vectors expressing various forms of CRY1 and CRY2. In contrast to nuclear localization in wild-type SCN, in the absence of CRY proteins, PER2 was predominantly cytoplasmic and more mobile, as measured by fluorescence recovery after photobleaching. Virally expressed CRY1 or CRY2 relocalized PER2 to the nucleus, initiated SCN circadian rhythms, and determined their period. We used translational switching to control CRY1 cellular abundance and found that low levels of CRY1 resulted in minimal relocalization of PER2, but yet, remarkably, were sufficient to initiate and maintain circadian rhythmicity. Importantly, the C-terminal tail was necessary for CRY1 to localize PER2 to the nucleus and to initiate SCN rhythms. In CRY1-null SCN, CRY1Δtail opposed PER2 nuclear localization and correspondingly shortened SCN period. Through manipulation of CRY proteins, we have obtained insights into the spatiotemporal behaviors of PER and CRY sitting at the heart of the TTFL molecular mechanism
Diverse tick-borne microorganisms identified in free-living ungulates in Slovakia
Background: Free-living ungulates are hosts of ixodid ticks and reservoirs of tick-borne microorganisms in central Europe and many regions around the world. Tissue samples and engorged ticks were obtained from roe deer, red deer, fallow deer, mouflon, and wild boar hunted in deciduous forests of south-western Slovakia. DNA isolated from these samples was screened for the presence of tick-borne microorganisms by PCR-based methods. Results: Ticks were found to infest all examined ungulate species. The principal infesting tick was Ixodes ricinus, identified on 90.4% of wildlife, and included all developmental stages. Larvae and nymphs of Haemaphysalis concinna were feeding on 9.6% of wildlife. Two specimens of Dermacentor reticulatus were also identified. Ungulates were positive for A. phagocytophilum and Theileria spp. Anaplasma phagocytophilum was found to infect 96.1% of cervids, 88.9% of mouflon, and 28.2% of wild boar, whereas Theileria spp. was detected only in cervids (94.6%). Importantly, a high rate of cervids (89%) showed mixed infections with both these microorganisms. In addition to A. phagocytophilum and Theileria spp., Rickettsia helvetica, R. monacensis, unidentified Rickettsia sp., Coxiella burnetii, "Candidatus Neoehrlichia mikurensis", Borrelia burgdorferi (s.l.) and Babesia venatorum were identified in engorged I. ricinus. Furthermore, A. phagocytophilum, Babesia spp. and Theileria spp. were detected in engorged H. concinna. Analysis of 16S rRNA and groEL gene sequences revealed the presence of five and two A. phagocytophilum variants, respectively, among which sequences identified in wild boar showed identity to the sequence of the causative agent of human granulocytic anaplasmosis (HGA). Phylogenetic analysis of Theileria 18S rRNA gene sequences amplified from cervids and engorged I. ricinus ticks segregated jointly with sequences of T. capreoli isolates into a moderately supported monophyletic clade. Conclusions: The findings indicate that free-living ungulates are reservoirs for A. phagocytophilum and Theileria spp. and engorged ixodid ticks attached to ungulates are good sentinels for the presence of agents of public and veterinary concern. Further analyses of the A. phagocytophilum genetic variants and Theileria species and their associations with vector ticks and free-living ungulates are required.Fil: Kazimírová, Mária. Slovak Academy of Sciences. Institute of Zoology; EslovaquiaFil: Hamšíková, Zuzana. Slovak Academy of Sciences. Institute of Zoology; EslovaquiaFil: Spitalská, Eva. Slovak Academy of Sciences. Institute of Virology. Biomedical Research Center,; EslovaquiaFil: Minichová, Lenka. Slovak Academy of Sciences. Institute of Virology. Biomedical Research Center,; EslovaquiaFil: Mahríková, Lenka. Slovak Academy of Sciences. Institute of Zoology; EslovaquiaFil: Caban, Radoslav. Široká ; EslovaquiaFil: Sprong, Hein. National Institute for Public Health and Environment.Laboratory for Zoonoses and Environmental Microbiology; Países BajosFil: Fonville, Manoj. National Institute for Public Health and Environment.Laboratory for Zoonoses and Environmental Microbiology; Países BajosFil: Schnittger, Leonhard. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kocianová, Elena. Slovak Academy of Sciences. Institute of Virology. Biomedical Research Center,; Eslovaqui
Model Selection for Degree-corrected Block Models
The proliferation of models for networks raises challenging problems of model
selection: the data are sparse and globally dependent, and models are typically
high-dimensional and have large numbers of latent variables. Together, these
issues mean that the usual model-selection criteria do not work properly for
networks. We illustrate these challenges, and show one way to resolve them, by
considering the key network-analysis problem of dividing a graph into
communities or blocks of nodes with homogeneous patterns of links to the rest
of the network. The standard tool for doing this is the stochastic block model,
under which the probability of a link between two nodes is a function solely of
the blocks to which they belong. This imposes a homogeneous degree distribution
within each block; this can be unrealistic, so degree-corrected block models
add a parameter for each node, modulating its over-all degree. The choice
between ordinary and degree-corrected block models matters because they make
very different inferences about communities. We present the first principled
and tractable approach to model selection between standard and degree-corrected
block models, based on new large-graph asymptotics for the distribution of
log-likelihood ratios under the stochastic block model, finding substantial
departures from classical results for sparse graphs. We also develop
linear-time approximations for log-likelihoods under both the stochastic block
model and the degree-corrected model, using belief propagation. Applications to
simulated and real networks show excellent agreement with our approximations.
Our results thus both solve the practical problem of deciding on degree
correction, and point to a general approach to model selection in network
analysis
Screening fungal endophytes derived from under-explored Egyptian marine habitats for antimicrobial and antioxidant properties in factionalised textiles
Marine endophytic fungi from under-explored locations are a promising source for the discovery of new bioactivities. Different endophytic fungi were isolated from plants and marine organisms collected from Wadi El-Natrun saline lakes and the Red Sea near Hurghada, Egypt. The isolated strains were grown on three different media, and their ethyl acetate crude extracts were evaluated for their antimicrobial activity against a panel of pathogenic bacteria and fungi as well as their antioxidant properties. Results showed that most of the 32 fungal isolates initially obtained possessed antimicrobial and antioxidant activities. The most potent antimicrobial extracts were applied to three different cellulose containing fabrics to add new multifunctional properties such as ultraviolet protection and antimicrobial functionality. For textile safety, the toxicity profile of the selected fungal extract was evaluated on human fibroblasts. The 21 strains displaying bioactivity were identified on molecular basis and selected for chemical screening and dereplication, which was carried out by analysis of the MS/MS data using the Global Natural Products Social Molecular Networking (GNPS) platform. The obtained molecular network revealed molecular families of compounds commonly produced by fungal strains, and in combination with manual dereplication, further previously reported metabolites were identified as well as potentially new derivatives
Two decades of antenatal and delivery care in Uganda: a cross-sectional study using Demographic and Health Surveys.
BACKGROUND: Uganda halved its maternal mortality to 343/100,000 live births between 1990 and 2015, but did not meet the Millennium Development Goal 5. Skilled, timely and good quality antenatal (ANC) and delivery care can prevent the majority of maternal/newborn deaths and stillbirths. We examine coverage, equity, sector of provision and content of ANC and delivery care between 1991 and 2011. METHODS: We conducted a repeated cross-sectional study using four Uganda Demographic and Health Surveys (1995, 2000, 2006 and 2011).Using the most recent live birth and adjusting for survey sampling, we estimated percentage and absolute number of births with ANC (any and 4+ visits), facility delivery, caesarean sections and complete maternal care. We assessed socio-economic differentials in these indicators by wealth, education, urban/rural residence, and geographic zone on the 1995 and 2011 surveys. We estimated the proportions of ANC and delivery care provided by the public and private (for-profit and not-for-profit) sectors, and compared content of ANC and delivery care between sectors. Statistical significance of differences were evaluated using chi-square tests. RESULTS: Coverage with any ANC remained high over the study period (> 90% since 2001) but was of insufficient frequency; < 50% of women who received any ANC reported 4+ visits. Facility-based delivery care increased slowly, reaching 58% in 2011. While significant inequalities in coverage by wealth, education, residence and geographic zone remained, coverage improved for all indicators among the lowest socio-economic groups of women over time. The private sector market share declined over time to 14% of ANC and 25% of delivery care in 2011. Only 10% of women with 4+ ANC visits and 13% of women delivering in facilities received all measured care components. CONCLUSIONS: The Ugandan health system had to cope with more than 30,000 additional births annually between 1991 and 2011. The majority of women in Uganda accessed ANC, but this contact did not result in care of sufficient frequency, content, and continuum of care (facility delivery). Providers in both sectors require quality improvements. Achieving universal health coverage and maternal/newborn SDGs in Uganda requires prioritising poor, less educated and rural women despite competing priorities for financial and human resources
Biomolecular Filters for Improved Separation of Output Signals in Enzyme Logic Systems Applied to Biomedical Analysis
Biomolecular logic systems processing biochemical input signals and producing
"digital" outputs in the form of YES/NO were developed for analysis of
physiological conditions characteristic of liver injury, soft tissue injury and
abdominal trauma. Injury biomarkers were used as input signals for activating
the logic systems. Their normal physiological concentrations were defined as
logic-0 level, while their pathologically elevated concentrations were defined
as logic-1 values. Since the input concentrations applied as logic 0 and 1
values were not sufficiently different, the output signals being at low and
high values (0, 1 outputs) were separated with a short gap making their
discrimination difficult. Coupled enzymatic reactions functioning as a
biomolecular signal processing system with a built-in filter property were
developed. The filter process involves a partial back-conversion of the
optical-output-signal-yielding product, but only at its low concentrations,
thus allowing the proper discrimination between 0 and 1 output values
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