27,134 research outputs found
Distribution of endothelial cell protein C/activated protein C receptor (EPCR) during mouse embryo development.
The endothelial cell protein C receptor (EPCR) augments protein C activation by the thrombomodulin.thrombin complex. Deletion of the EPCR gene in mice has been reported to lead to embryonic lethality before embryonic day 10 (E10.0). To identify potential mechanisms responsible for this lethality, we performed an immunohistological analysis of EPCR distribution during mouse embryogenesis. EPCR was detected in the trophoblast giant cells at the feto-maternal boundary from E7.5 and at later time points in the trophoblasts of the placenta, suggesting a role in the haemostatic regulation of the maternal blood that irrigates these surfaces. In the embryo, EPCR was weakly detected in aortic endothelial cells from E13.5. Thereafter, EPCR levels increased in certain large blood vessels endothelial cells suggesting that the specificity of EPCR to large vessels is conferred in utero. However, not until postnatal day 7 did the intensity and distribution of EPCR staining mimic that observed in adult mice
Pseudospin-1 Physics of Photonic Crystals.
We review some recent progress in the exploration of pseudospin-1 physics using dielectric photonic crystals (PCs). We show some physical implications of the PCs exhibiting an accidental degeneracy induced conical dispersion at the Î point, such as the realization of zero refractive index medium and the zero Berry phase of a loop around the nodal point. The photonic states of such PCs near the Dirac-like point can be described by an effective spin-orbit Hamiltonian of pseudospin-1. The wave propagation in the positive, negative, and zero index media can be unified within a framework of pseudospin-1 description. A scale change in PCs results in a rigid band shift of the Dirac-like cone, allowing for the manipulation of waves in pseudospin-1 systems in much the same way as applying a gate voltage in pseudospin-1/2 graphene. The transport of waves in pseudospin-1 systems exhibits many interesting phenomena, including super Klein tunneling, robust supercollimation, and unconventional Anderson localization. The transport properties of pseudospin-1 systems are distinct from their counterparts in pseudospin-1/2 systems, which will also be presented for comparison
Topological Interactions in Warped Extra Dimensions
Topological interactions will be generated in theories with compact extra
dimensions where fermionic chiral zero modes have different localizations. This
is the case in many warped extra dimension models where the right-handed top
quark is typically localized away from the left-handed one. Using
deconstruction techniques, we study the topological interactions in these
models. These interactions appear as trilinear and quadrilinear gauge boson
couplings in low energy effective theories with three or more sites, as well as
in the continuum limit. We derive the form of these interactions for various
cases, including examples of Abelian, non-Abelian and product gauge groups of
phenomenological interest. The topological interactions provide a window into
the more fundamental aspects of these theories and could result in unique
signatures at the Large Hadron Collider, some of which we explore.Comment: 40 pages, 10 figures, 2 tables; modifications in the KK parity
discussion, final version at JHE
A detailed analysis of online pharmacy characteristics to inform safe usage by patients
Background: Evidence suggests that consumers potentially put themselves at risk when purchasing medicines on-line. Whilst logos provided by regulators may provide some level of reassurance there may be other indicators which could be used by consumers to identify those websites which may be safely used. Objectives: Identify characteristics of on-line pharmacies which are related to whether websites are regulated or non-regulated and those characteristics which could be used by patients to increase the likelihood of accessing regulated sites. Setting: Online pharmacies which supply diazepam, fluoxetine and simvastatin. Methods: Using piloted search terms via Google and Yahoo search engines, identified websites were screened for regulatory status, adherence to regulatory standards, administrative requirements, clinical assessment requirements and additional details deemed to be of relevance to a user. Characteristics of regulated and non-regulated (defined as those with an absence of a correctly linked regulatory logo) websites were compared to identify differences which could be used to improve patient safety. Main outcome measure: Regulatory status, adherence to regulatory standards, quality of information provision, barriers to medicines access. Results: 113 websites sold diazepam, fluoxetine and simvastatin; were identified within the first 100 results. Less than quarter were found to be regulated online pharmacies. 80 websites were willing to sell the medication without a prescription. The unregulated internet pharmacy websites (defined as those with an absence of a correctly linked regulatory logo) were found to adhere more closely to the clinical criteria, were less significantly likely to disclose a contact name and address, telephone number of the pharmacy or demand a prescription prior to sale (P\0.05, Fisherâs Exact). Conclusions: The three prescription-only medicines which are liable to abuse, have potentially serious interactions and require counselling to ensure patient safety are readily available via the internet. When purchasing medicines via this route UK consumers should be made aware of the importance of regulatory logos and additionally should ensure that the seller can be meaningfully contacted by the contact details provided. The provision of clinical information should not be used alone as an indication of the sellerâs provenance
b-coloring is NP-hard on co-bipartite graphs and polytime solvable on tree-cographs
A b-coloring of a graph is a proper coloring such that every color class
contains a vertex that is adjacent to all other color classes. The b-chromatic
number of a graph G, denoted by \chi_b(G), is the maximum number t such that G
admits a b-coloring with t colors. A graph G is called b-continuous if it
admits a b-coloring with t colors, for every t = \chi(G),\ldots,\chi_b(G), and
b-monotonic if \chi_b(H_1) \geq \chi_b(H_2) for every induced subgraph H_1 of
G, and every induced subgraph H_2 of H_1.
We investigate the b-chromatic number of graphs with stability number two.
These are exactly the complements of triangle-free graphs, thus including all
complements of bipartite graphs. The main results of this work are the
following:
- We characterize the b-colorings of a graph with stability number two in
terms of matchings with no augmenting paths of length one or three. We derive
that graphs with stability number two are b-continuous and b-monotonic.
- We prove that it is NP-complete to decide whether the b-chromatic number of
co-bipartite graph is at most a given threshold.
- We describe a polynomial time dynamic programming algorithm to compute the
b-chromatic number of co-trees.
- Extending several previous results, we show that there is a polynomial time
dynamic programming algorithm for computing the b-chromatic number of
tree-cographs. Moreover, we show that tree-cographs are b-continuous and
b-monotonic
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Evidence for clonal selection of gamma/delta T cells in response to a human pathogen.
T cells bearing gamma/delta antigen receptors comprise a resident population of intraepithelial lymphocytes in organs such as skin, gut, and lungs, where they are strategically located to contribute to the initial defense against infection. An important unsolved question about antigen-driven gamma/delta T cell responses regards the breadth of their T cell receptor (TCR) repertoire, since many specific epithelial compartments in mice display limited diversity. We have examined the diversity of TCR delta gene expression among human gamma/delta T cells from skin lesions induced by intradermal challenge with Mycobacterium leprae. We show that the vast majority of gamma/delta cells from M. leprae lesions use either V delta 1-J delta 1 or V delta 2-J delta 1 gene rearrangements and, within a given region of the lesion, display limited junctional diversity. This contrasts markedly with the extensive diversity of gamma/delta T cells from peripheral blood of these same individuals, as well as skin from normal donors. These results indicate that the gamma/delta response to M. leprae involves the selection of a limited number of clones from among a diverse repertoire, probably in response to specific mycobacterial and/or host antigens
Prevalence of placenta Plasmodium parasitemia and pregnancy outcome in asymptomatic patients at delivery in a University Teaching Hospital in Nigeria
Background: Malaria is an important public health issue in pregnancy association with poor fetal and maternal outcome, especially in malaria endemic area like Nigeria.Objective: The objective was to determine the prevalence of placental malaria in asymptomatic women in labor and to compare the fetal and maternal outcome between affected and unaffected women.Subjects and Methods: A prospective cross-sectional study of 210 women who delivered at a tertiary health facility in Nigeria. Participantsf peripheral venous blood, cord blood, and placental blood samples were examined microscopically for the presence of malaria parasite. Data collected were analyzed using SPSS version 16.Results: Prevalence of placental malaria was 65.2%. Nulliparity was significantly associated with placental malaria (X2 = 21.32, P = 0.0000039, odds ratio [OR] =5.6). Poor compliance to intermittent preventive therapy was significantly associated with placental malaria (X2 = 16.67, P = 0.00004). The mean gestational age at delivery was 38.57 « 1.7 weeks and 12.85% of women had preterm delivery. Sixty.seven (31.9%) women had anemia and malaria parasitemia was significantly associated with anemia (X2 = 8.34, P = 0.0039, OR = 2.6). Fourteen (6.67%) babies had low birth weight, but placental malaria was not significantly associated with low birth weight (X2 = 0.03, P = 0.87).Conclusion: There is a high prevalence of placental malaria in the study population. Nulliparity, poor drug compliance, and maternal anemia were associated with placental malaria.Key words: Malaria, Nigeria, placenta, pregnancy outcome, prevalenc
PGB pair production at LHC and ILC as a probe of the topcolor-assisted technicolor models
The topcolor-assisted technicolor (TC2) model predicts some light pseudo
goldstone bosons (PGBs), which may be accessible at the LHC or ILC. In this
work we study the pair productions of the charged or neutral PGBs at the LHC
and ILC. For the productions at the LHC we consider the processes proceeding
through gluon-gluon fusion and quark-antiquark annihilation, while for the
productions at the ILC we consider both the electron-positron collision and the
photon-photon collision. We find that in a large part of parameter space the
production cross sections at both colliders can be quite large compared with
the low standard model backgrounds. Therefore, in future experiments these
productions may be detectable and allow for probing TC2 model.Comment: 26 pages, 16 figures. slight changes in the text; notations for
curves changed; references adde
Multiple Instance Learning for Heterogeneous Images: Training a CNN for Histopathology
Multiple instance (MI) learning with a convolutional neural network enables
end-to-end training in the presence of weak image-level labels. We propose a
new method for aggregating predictions from smaller regions of the image into
an image-level classification by using the quantile function. The quantile
function provides a more complete description of the heterogeneity within each
image, improving image-level classification. We also adapt image augmentation
to the MI framework by randomly selecting cropped regions on which to apply MI
aggregation during each epoch of training. This provides a mechanism to study
the importance of MI learning. We validate our method on five different
classification tasks for breast tumor histology and provide a visualization
method for interpreting local image classifications that could lead to future
insights into tumor heterogeneity
Altered distribution of mucosal NK cells during HIV infection.
The human gut mucosa is a major site of human immunodeficiency virus (HIV) infection and infection-associated pathogenesis. Increasing evidence shows that natural killer (NK) cells have an important role in control of HIV infection, but the mechanism(s) by which they mediate antiviral activity in the gut is unclear. Here, we show that two distinct subsets of NK cells exist in the gut, one localized to intraepithelial spaces (intraepithelial lymphocytes, IELs) and the other to the lamina propria (LP). The frequency of both subsets of NK cells was reduced in chronic infection, whereas IEL NK cells remained stable in spontaneous controllers with protective killer immunoglobulin-like receptor/human leukocyte antigen genotypes. Both IEL and LP NK cells were significantly expanded in immunological non-responsive patients, who incompletely recovered CD4+ T cells on highly active antiretroviral therapy (HAART). These data suggest that both IEL and LP NK cells may expand in the gut in an effort to compensate for compromised CD4+ T-cell recovery, but that only IEL NK cells may be involved in providing durable control of HIV in the gut
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