272 research outputs found
Nonmagnetic-Defect-Induced Magnetism in Graphene
It is shown that a strong impurity potential induces short-range
antiferromagnetic (ferrimagnetic) order around itself in a Hubbard model on a
half-filled honeycomb lattice. This implies that short-range magnetic order is
induced in monolayer graphene by a nonmagnetic defect such as a vacancy with
full hydrogen termination or a chemisorption defect.Comment: 5 pages, 8 figure
XBP-1 regulates signal transduction, transcription factors and bone marrow colonization in B cells
XBP-1, a transcription factor that drives the unfolded protein response (UPR), is activated in B cells when they differentiate to plasma cells. Here, we show that in the B cells, whose capacity to secrete IgM has been eliminated, XBP-1 is induced normally on induction of differentiation, suggesting that activation of XBP-1 in B cells is a differentiation-dependent event, but not the result of a UPR caused by the abundant synthesis of secreted IgM. Without XBP-1, B cells fail to signal effectively through the B-cell receptor. The signalling defects lead to aberrant expression of the plasma cell transcription factors IRF4 and Blimp-1, and altered levels of activation-induced cytidine deaminase and sphingosine-1-phosphate receptor. Using XBP-1-deficient/Blimp-1-GFP transgenic mice, we find that XBP-1-deficient B cells form antibody-secreting plasmablasts in response to initial immunization; however, these plasmablasts respond ineffectively to CXCL12. They fail to colonize the bone marrow and do not sustain antibody production. These findings define the role of XBP-1 in normal plasma cell development and have implications for management of B-cell malignancies
BINGO: A code for the efficient computation of the scalar bi-spectrum
We present a new and accurate Fortran code, the BI-spectra and
Non-Gaussianity Operator (BINGO), for the efficient numerical computation of
the scalar bi-spectrum and the non-Gaussianity parameter f_{NL} in single field
inflationary models involving the canonical scalar field. The code can
calculate all the different contributions to the bi-spectrum and the parameter
f_{NL} for an arbitrary triangular configuration of the wavevectors. Focusing
firstly on the equilateral limit, we illustrate the accuracy of BINGO by
comparing the results from the code with the spectral dependence of the
bi-spectrum expected in power law inflation. Then, considering an arbitrary
triangular configuration, we contrast the numerical results with the analytical
expression available in the slow roll limit, for, say, the case of the
conventional quadratic potential. Considering a non-trivial scenario involving
deviations from slow roll, we compare the results from the code with the
analytical results that have recently been obtained in the case of the
Starobinsky model in the equilateral limit. As an immediate application, we
utilize BINGO to examine of the power of the non-Gaussianity parameter f_{NL}
to discriminate between various inflationary models that admit departures from
slow roll and lead to similar features in the scalar power spectrum. We close
with a summary and discussion on the implications of the results we obtain.Comment: v1: 5 pages, 5 figures; v2: 35 pages, 11 figures, title changed,
extensively revised; v3: 36 pages, 11 figures, to appear in JCAP. The BINGO
code is available online at
http://www.physics.iitm.ac.in/~sriram/bingo/bingo.htm
Molecules participating in insect immunity of Sarcophaga peregrina
Pricking the body wall of Sarcophaga
peregrina (flesh fly) larvae with a needle activated the immune system of this insect and induced various immune molecules, including antibacterial proteins, in the hemolymph. In this review, I summarize and discuss the functions of these immune molecules, with particular emphasis on the dual roles of some of these molecules in defense and development
Spontaneous preterm labor is associated with an increase in the proinflammatory signal transducer TLR4 receptor on maternal blood monocytes
<p>Abstract</p> <p>Background</p> <p>Localized inflammation and increased expression of TLR4 receptors within the uterus has been implicated in the pathogenesis of preterm labor. It remains unclear whether intrauterine inflammatory responses activate the maternal peripheral circulatory system. Therefore we determined whether increased TLR4 expression is present in the peripheral maternal white blood cells of women with spontaneous preterm labor.</p> <p>Methods</p> <p>This is a cross-sectional study of 41 preterm labor cases and 41 non-preterm controls. For each case and control sample, RNA was purified from white blood cells and TLR4 mRNA pool size was evaluated by quantitative PCR. Protein expression levels were determined by flow cytometry. Statistical evaluation using multiple linear regressions was used to determine any significant differences between the cases and controls. The purpose was to determine association prevalence of TLR4 levels and preterm labor.</p> <p>Results</p> <p>Adjusted mean TLR4 mRNA levels of 0.788 ± 0.037 (standard error) for preterm labor and 0.348 ± 0.038 for the corresponding pregnant control women were statistically significantly different <it>(P </it>= 0.002). Using the lower 95% confidence interval of the mean expression level in PTL subjects (0.7) as a cutoff value for elevated TLR4 mRNA levels, 25/41 (60.9%) of PTL patients expressed elevated TLR4 mRNA as compared to 0/41 (0%) in control subjects. The TLR4 receptor levels in the granulocyte fraction of white blood cells from preterm labor and pregnant controls were similar. However, TLR4<sup>+</sup>/CD14<sup>+</sup>monocytes were 2.3 times more frequent (70% vs. 30%) and TLR4 also had a 2.6-fold higher density (750 vs. 280 molecules per cell) in preterm labor women compared with pregnant controls. There was no difference in the levels of TLR4 in patients at term.</p> <p>Conclusions</p> <p>Patients with preterm labor exhibited elevated levels of CD14<sup>+ </sup>maternal blood monocytes each bearing enhanced expression of TLR4, indicating that the peripheral circulatory system is activated in patients with preterm labor. Elevated leukocyte TLR4 levels may be a useful biomarker associated with preterm labor.</p
Spin-half paramagnetism in graphene induced by point defects
Using magnetization measurements, we show that point defects in graphene -
fluorine adatoms and irradiation defects (vacancies) - carry magnetic moments
with spin 1/2. Both types of defects lead to notable paramagnetism but no
magnetic ordering could be detected down to liquid helium temperatures. The
induced paramagnetism dominates graphene's low-temperature magnetic properties
despite the fact that maximum response we could achieve was limited to one
moment per approximately 1000 carbon atoms. This limitation is explained by
clustering of adatoms and, for the case of vacancies, by losing graphene's
structural stability.Comment: 14 pages, 14 figure
Association of XRCC1 Arg399GIn and Tp53 Arg72Pro polymorphisms and increased risk of uterine leiomyoma - A case-control study
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