2,824 research outputs found
Codimension 3 Arithmetically Gorenstein Subschemes of projective -space
We study the lowest dimensional open case of the question whether every
arithmetically Cohen--Macaulay subscheme of is glicci, that is,
whether every zero-scheme in is glicci. We show that a set of points in general position in \PP^3 admits no strictly descending
Gorenstein liaison or biliaison. In order to prove this theorem, we establish a
number of important results about arithmetically Gorenstein zero-schemes in
.Comment: to appear in Annales de l'Institut Fourie
Body mass index, abdominal fatness, fat mass and the risk of atrial fibrillation: a systematic review and dose–response meta-analysis of prospective studies
Different adiposity measures have been associ- ated with increased risk of atrial fibrillation, however, results have previously only been summarized for BMI. We therefore conducted a systematic review and meta- analysis of prospective studies to clarify the association between different adiposity measures and risk of atrial fibrillation. PubMed and Embase databases were searched up to October 24th 2016. Summary relative risks (RRs) were calculated using random effects models. Twenty-nine unique prospective studies (32 publications) were included. Twenty-five studies (83,006 cases, 2,405,381 participants) were included in the analysis of BMI and atrial fibrillation. The summary RR was 1.28 (95% confidence interval: 1.20–1.38, I 2 = 97%) per 5 unit increment in BMI, 1.18 (95% CI: 1.12–1.25, I 2 = 73%, n = 5) and 1.32 (95% CI: 1.16–1.51, I 2 = 91%, n = 3) per 10 cm increase in waist and hip circumference, respectively, 1.09 (95% CI: 1.02–1.16, I 2 = 44%, n = 4) per 0.1 unit increase in waist- to-hip ratio, 1.09 (95% CI: 1.02–1.16, I 2 = 94%, n = 4) per 5 kg increase in fat mass, 1.10 (95% CI: 0.92–1.33, I 2 = 90%, n = 3) per 10% increase in fat percentage, 1.10 (95% CI: 1.08–1.13, I 2 = 74%, n = 10) per 5 kg increase in weight, and 1.08 (95% CI: 0.97–1.19, I 2 = 86%, n = 2) per 5% increase in weight gain. The association between BMI and atrial fibrillation was non- linear, p nonlinearity \ 0.0001, with a stronger association at higher BMI levels, however, increased risk was observed even at a BMI of 22–24 compared to 20. In conclusion, general and abdominal adiposity and higher body fat mass increase the risk of atrial fibrillation
Non-Fermi liquid behavior of SrRuO_3 -- evidence from infrared conductivity
The reflectivity of the itinerant ferromagnet SrRuO_3 has been measured
between 50 and 25,000 cm-1 at temperatures ranging from 40 to 300 K, and used
to obtain conductivity, scattering rate, and effective mass as a function of
frequency and temperature. We find that at low temperatures the conductivity
falls unusually slowly as a function of frequency (proportional to
\omega^{-1/2}), and at high temperatures it even appears to increase as a
function of frequency in the far-infrared limit. The data suggest that the
charge dynamics of SrRuO_3 are substantially different from those of
Fermi-liquid metals.Comment: 4 pages, 3 postscript figure
Time domain Dielectric Spectroscopy Study of Human Cells. II. Normal and Malignant White Blood Cells
open access articleThe dielectric properties of human lymphocyte suspensions were studied by time domain dielectric spectroscopy (TDDS). Nine populations of malignant and normal lymphocytes were investigated. Analysis of the dielectric parameters of cell structural parts were performed in the framework of Maxwell^Wagner mixture formula and the double-shell model of cell. The specific capacitance of the cell membranes was estimated by the Hanai^Asami^Koisumi formula. It was shown that the dielectric permittivity, capacitance and conductivity values of cell membranes are higher for normal lymphocytes than for the malignant ones. The difference of the same parameters for normal B- and T-cells is also discussed
Ferromagnetism in the Mott insulator Ba2NaOsO6
Results are presented of single crystal structural, thermodynamic, and
reflectivity measurements of the double-perovskite Ba2NaOsO6. These
characterize the material as a 5d^1 ferromagnetic Mott insulator with an
ordered moment of ~0.2 Bohr magnetons per formula unit and TC = 6.8(3) K. The
magnetic entropy associated with this phase transition is close to Rln2,
indicating that the quartet groundstate anticipated from consideration of the
crystal structure is split, consistent with a scenario in which the
ferromagnetism is associated with orbital ordering.Comment: 5 pages, 5 figures, added reference
Detailed Studies of Pixelated CZT Detectors Grown with the Modified Horizontal Bridgman Method
The detector material Cadmium Zinc Telluride (CZT), known for its high
resolution over a broad energy range, is produced mainly by two methods: the
Modified High-Pressure Bridgman (MHB) and the High-Pressure Bridgman (HPB)
process. This study is based on MHB CZT substrates from the company Orbotech
Medical Solutions Ltd. with a detector size of 2.0x2.0x0.5 cm^3, 8x8 pixels and
a pitch of 2.46 mm. Former studies have emphasized only on the cathode material
showing that high-work-function improve the energy resolution at lower
energies. Therfore, we studied the influence of the anode material while
keeping the cathode material constant. We used four different materials:
Indium, Titanium, Chromium and Gold with work-functions between 4.1 eV and 5.1
eV. The low work-function materials Indium and Titanium achieved the best
performance with energy resolutions: 2.0 keV (at 59 keV) and 1.9 keV (at 122
keV) for Titanium; 2.1 keV (at 59 keV) and 2.9 keV (at 122 keV) for Indium.
These detectors are very competitive compared with the more expensive ones
based on HPB material if one takes the large pixel pitch of 2.46 mm into
account. We present a detailed comparison of our detector response with 3-D
simulations, from which we determined the mobility-lifetime-products for
electrons and holes. Finally, we evaluated the temperature dependency of the
detector performance and mobility-lifetime-products, which is important for
many applications. With decreasing temperature down to -30C the breakdown
voltage increases and the electron mobility-lifetime-product decreases by about
30% over a range from 20C to -30C. This causes the energy resolution to
deteriorate, but the concomitantly increasing breakdown voltage makes it
possible to increase the applied bias voltage and restore the full performance.Comment: Accepted for publication in Astroparticle Physics, 25 pages, 13
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Lysis mediated by T cells and restricted by H-2 antigen of target cells infected with vaccinia virus
VARIOUS virus infections lead to the formation of cytotoxic lymphocytes (CL), which are capable of killing virus-infected target cells1−4. Specific lysis of target cells infected with 51Cr-labelled vaccinia virus could be observed when investigating the cell-mediated cytotoxic reaction to vaccinia virus5; the CL could be characterised as a T cell. The sensitised lymphocytes from C3H mice could only kill syngeneic L929 cells infected with vaccinia virus, whereas lysis by sensitised lymphocytes derived from DBA/2 mice was restricted to the syngeneic infected mastocytoma P815X2 cells. In the lymphocytic choriomeningitis infection the target cell lysis was shown to be restricted by H-2 antigen6. We report here experiments with primary fibroblasts of the mouse strains C3H, DBA/2 and the (C3H DBA/2)F1 generation were designed to affirm that the effector phase of virus-specific lysis of target cells mediated by T cells is restricted by H-2 antigen even in the vaccinia virus infection. Further experiments with H-2 alloantisera were performed to indicate the close local relationship between H-2 antigens and viral surface antigens
5Regulation of myogenesis via kinase driven activation of DPF3a, a BAF complex member and its interaction with transcription repressor HEY1
Changes in the hydrogen-bonding strength of internal water molecules and cysteine residues in the conductive state of channelrhodopsin-1
Water plays an essential role in the structure and function of proteins, particularly in the less understood class of membrane proteins. As the first of its kind, channelrhodopsin is a light-gated cation channel and paved the way for the new and vibrant field of optogenetics, where nerve cells are activated by light. Still, the molecular mechanism of channelrhodopsin is not understood. Here, we applied time-resolved FT-IR difference spectroscopy to channelrhodopsin-1 from Chlamydomonas augustae. It is shown that the (conductive) P2 380 intermediate decays with τ ≈ 40 ms and 200 ms after pulsed excitation. The vibrational changes between the closed and the conductive states were analyzed in the X-H stretching region (X = O, S, N), comprising vibrational changes of water molecules, sulfhydryl groups of cysteine side chains and changes of the amide A of the protein backbone. The O-H stretching vibrations of ¿dangling¿ water molecules were detected in two different states of the protein using H2 18O exchange. Uncoupling experiments with a 1:1 mixture of H2O:D2O provided the natural uncoupled frequencies of the four O-H (and O-D) stretches of these water molecules, each with a very weakly hydrogen-bonded O-H group (3639 and 3628 cm−1) and with the other O-H group medium (3440 cm−1) to moderately strongly (3300 cm−1) hydrogen-bonded. Changes in amide A and thiol vibrations report on global and local changes, respectively, associated with the formation of the conductive state. Future studies will aim at assigning the respective cysteine group(s) and at localizing the ¿dangling¿ water molecules within the protein, providing a better understanding of their functional relevance in CaChR1
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