420 research outputs found
Speciation by genome duplication: Repeated origins and genomic composition of the recently formed allopolyploid species Mimulus peregrinus
Natural Environment Research Council. Grant Number: NE/J012645/
Generalized iterated wreath products of symmetric groups and generalized rooted trees correspondence
Consider the generalized iterated wreath product of symmetric groups. We give a complete description of the traversal
for the generalized iterated wreath product. We also prove an existence of a
bijection between the equivalence classes of ordinary irreducible
representations of the generalized iterated wreath product and orbits of labels
on certain rooted trees. We find a recursion for the number of these labels and
the degrees of irreducible representations of the generalized iterated wreath
product. Finally, we give rough upper bound estimates for fast Fourier
transforms.Comment: 18 pages, to appear in Advances in the Mathematical Sciences. arXiv
admin note: text overlap with arXiv:1409.060
Predicting live birth, preterm and low birth weight infant after in-vitro fertilisation: a prospective study of 144018 treatment cycles
Background
The extent to which baseline couple characteristics affect the probability of live birth and adverse perinatal outcomes after assisted conception is unknown.
Methods and Findings
We utilised the Human Fertilisation and Embryology Authority database to examine the predictors of live birth in all in vitro fertilisation (IVF) cycles undertaken in the UK between 2003 and 2007 (n = 144,018). We examined the potential clinical utility of a validated model that pre-dated the introduction of intracytoplasmic sperm injection (ICSI) as compared to a novel model. For those treatment cycles that resulted in a live singleton birth (n = 24,226), we determined the associates of potential risk factors with preterm birth, low birth weight, and macrosomia. The overall rate of at least one live birth was 23.4 per 100 cycles (95% confidence interval [CI] 23.2–23.7). In multivariable models the odds of at least one live birth decreased with increasing maternal age, increasing duration of infertility, a greater number of previously unsuccessful IVF treatments, use of own oocytes, necessity for a second or third treatment cycle, or if it was not unexplained infertility. The association of own versus donor oocyte with reduced odds of live birth strengthened with increasing age of the mother. A previous IVF live birth increased the odds of future success (OR 1.58, 95% CI 1.46–1.71) more than that of a previous spontaneous live birth (OR 1.19, 95% CI 0.99–1.24); p-value for difference in estimate <0.001. Use of ICSI increased the odds of live birth, and male causes of infertility were associated with reduced odds of live birth only in couples who had not received ICSI. Prediction of live birth was feasible with moderate discrimination and excellent calibration; calibration was markedly improved in the novel compared to the established model. Preterm birth and low birth weight were increased if oocyte donation was required and ICSI was not used. Risk of macrosomia increased with advancing maternal age and a history of previous live births. Infertility due to cervical problems was associated with increased odds of all three outcomes—preterm birth, low birth weight, and macrosomia.
Conclusions
Pending external validation, our results show that couple- and treatment-specific factors can be used to provide infertile couples with an accurate assessment of whether they have low or high risk of a successful outcome following IVF
Census politics in deeply divided societies
Population censuses in societies that are deeply divided along ethnic, religious or linguistic lines can be sensitive affairs – particularly where political settlements seek to maintain peace through the proportional sharing of power between groups. This brief sets out some key findings from a research project investigating the relationship between census politics and the design of political institutions in Bosnia and Herzegovina, Kenya, Lebanon and Northern Ireland
Strongly linked current flow in polycrystalline forms of the new superconductor MgB2
The discovery of superconductivity at 39 K in MgB2[1] raises many issues. One
of the central questions is whether this new superconductor resembles a
high-temperature-cuprate superconductor or a low-temperature metallic
superconductor in terms of its current carrying characteristics in applied
magnetic fields. In spite of the very high transition temperatures of the
cuprate superconductors, their performance in magnetic fields has several
drawbacks[2]. Their large anisotropy restricts high bulk current densities to
much less than the full magnetic field-temperature (H-T) space over which
superconductivity is found. Further, weak coupling across grain boundaries
makes transport current densities in untextured polycrystalline forms low and
strongly magnetic field sensitive[3,4]. These studies of MgB2 address both
issues. In spite of the multi-phase, untextured, nano-scale sub-divided nature
of our samples, supercurrents flow throughout without the strong sensitivity to
weak magnetic fields characteristic of Josephson-coupled grains[3].
Magnetization measurements over nearly all of the superconducting H-T plane
show good temperature scaling of the flux pinning force, suggestive of a
current density determined by flux pinning. At least two length scales are
suggested by the magnetization and magneto optical (MO) analysis but the cause
of this seems to be phase inhomogeneity, porosity, and minority insulating
phase such as MgO rather than by weakly coupled grain boundaries. Our results
suggest that polycrystalline ceramics of this new class of superconductor will
not be compromised by the weak link problems of the high temperature
superconductors, a conclusion with enormous significance for applications if
higher temperature analogs of this compound can be discovered
Would school closure for the 2009 H1N1 influenza epidemic have been worth the cost?: a computational simulation of Pennsylvania
<p>Abstract</p> <p>Background</p> <p>During the 2009 H1N1 influenza epidemic, policy makers debated over whether, when, and how long to close schools. While closing schools could have reduced influenza transmission thereby preventing cases, deaths, and health care costs, it may also have incurred substantial costs from increased childcare needs and lost productivity by teachers and other school employees.</p> <p>Methods</p> <p>A combination of agent-based and Monte Carlo economic simulation modeling was used to determine the cost-benefit of closing schools (vs. not closing schools) for different durations (range: 1 to 8 weeks) and symptomatic case incidence triggers (range: 1 to 30) for the state of Pennsylvania during the 2009 H1N1 epidemic. Different scenarios varied the basic reproductive rate (R<sub>0</sub>) from 1.2, 1.6, to 2.0 and used case-hospitalization and case-fatality rates from the 2009 epidemic. Additional analyses determined the cost per influenza case averted of implementing school closure.</p> <p>Results</p> <p>For all scenarios explored, closing schools resulted in substantially higher net costs than not closing schools. For R<sub>0 </sub>= 1.2, 1.6, and 2.0 epidemics, closing schools for 8 weeks would have resulted in median net costs of 8.0 - 14,185 (30,565) for R<sub>0 </sub>= 1.2, 9,501 - 23,483 (50,926) for R<sub>0 </sub>= 2.0.</p> <p>Conclusions</p> <p>Our study suggests that closing schools during the 2009 H1N1 epidemic could have resulted in substantial costs to society as the potential costs of lost productivity and childcare could have far outweighed the cost savings in preventing influenza cases.</p
Firsthand Experience and The Subsequent Role of Reflected Knowledge in Cultivating Trust in Global Collaboration
While scholars contend that firsthand experience - time spent onsite observing the people, places, and norms of a distant locale - is crucial in globally distributed collaboration, how such experience actually affects interpersonal dynamics is poorly understood. Based on 47 semistructured interviews and 140 survey responses in a global chemical company, this paper explores the effects of firsthand experience on intersite trust. We find firsthand experience leads not just to direct knowledge of the other, but also knowledge of the self as seen through the eyes of the other - what we call “reflected knowledge”. Reflected and direct knowledge, in turn, affect trust through identification, adaptation, and reduced misunderstandings
Incidence and Tracking of Escherichia coli O157:H7 in a Major Produce Production Region in California
Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157:H7 (EcO157). Between 1995–2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased flow rate in the rivers. Approximately 1000 EcO157 isolates obtained from cultures of>100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness
Characterising the KMP-11 and HSP-70 recombinant antigens' humoral immune response profile in chagasic patients
11 pages, 6 figures.-- The pre-publication history for this paper can be accessed
here:
http://www.biomedcentral.com/1471-2334/9/186/pre
pubBackground: Antigen specificity and IgG subclass could be significant in the natural history of
Chagas' disease. The relationship between the different stages of human Chagas' disease and the
profiles of total IgG and its subclasses were thus analysed here; they were directed against a crude
T. cruzi extract and three recombinant antigens: the T. cruzi kinetoplastid membrane protein-11
(rKMP-11), an internal fragment of the T. cruzi HSP-70 protein192-433, and the entire Trypanosoma
rangeli HSP-70 protein.
Methods: Seventeen Brazilian acute chagasic patients, 50 Colombian chronic chagasic patients (21
indeterminate and 29 cardiopathic patients) and 30 healthy individuals were included. Total IgG and
its subtypes directed against the above-mentioned recombinant antigens were determined by
ELISA tests.
Results: The T. cruzi KMP-11 and T. rangeli HSP-70 recombinant proteins were able to distinguish
both acute from chronic chagasic patients and infected people from healthy individuals. Specific
antibodies to T. cruzi crude antigen in acute patients came from IgG3 and IgG4 subclasses whereas
IgG1 and IgG3 were the prevalent isotypes in indeterminate and chronic chagasic patients. By
contrast, the specific prominent antibodies in all disease stages against T. cruzi KMP-11 and T. rangeli
HSP-70 recombinant antigens were the IgG1 subclass.This work was supported by Colciencias Research project No. 1203-333-
18692. IDF was supported by Colciencias and the Universidad Javeriana's
Young Researcher 2008 Programme (Bogotá, Colombia). MCT and MCL
were supported by P06-CTS-02242 Grant from PAI (Junta de Andalucia)
and RICET-RD06/0021-0014, Spain. MS received financial support from the
Brazilian agency - CNPq.Peer reviewe
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