7,164 research outputs found
Building a St\"uckelberg Portal
We construct explicit string theory models realizing the recently proposed
"St\"uckelberg Portal" scenario, a framework for building Z' mediation models
without the need to introduce unwanted exotic matter charged under the Standard
Model. This scenario can be viewed purely field-theoretically, although it is
particularly well motivated from string theory. By analyzing carefully the
St\"uckelberg couplings between the Abelian gauge bosons and the RR axions, we
construct the first global intersecting brane models which extend the Standard
Model with a genuine hidden sector, to which it is nonetheless connected via
U(1) mass mixings. Utilizing the explicit models we construct, we discuss some
broad phenomenological properties and experimental implications of this
scenario such as Z-Z' mixings, dark matter stability and relic density, and
supersymmetry mediation. With an appropriate confining hidden sector, our setup
also provides a minimal realization of the hidden valley scenario. We further
explore the possibility of obtaining small Z' masses from a large ensemble of
U(1) bosons. Related to the St\"uckelberg portal are two mechanisms that
connect the visible and the hidden sectors, namely mediation by
non-perturbative operators and the hidden photon scenario, on which we briefly
comment.Comment: 39 pages, 11 figure
Parallel Tempering Simulation of the three-dimensional Edwards-Anderson Model with Compact Asynchronous Multispin Coding on GPU
Monte Carlo simulations of the Ising model play an important role in the
field of computational statistical physics, and they have revealed many
properties of the model over the past few decades. However, the effect of
frustration due to random disorder, in particular the possible spin glass
phase, remains a crucial but poorly understood problem. One of the obstacles in
the Monte Carlo simulation of random frustrated systems is their long
relaxation time making an efficient parallel implementation on state-of-the-art
computation platforms highly desirable. The Graphics Processing Unit (GPU) is
such a platform that provides an opportunity to significantly enhance the
computational performance and thus gain new insight into this problem. In this
paper, we present optimization and tuning approaches for the CUDA
implementation of the spin glass simulation on GPUs. We discuss the integration
of various design alternatives, such as GPU kernel construction with minimal
communication, memory tiling, and look-up tables. We present a binary data
format, Compact Asynchronous Multispin Coding (CAMSC), which provides an
additional speedup compared with the traditionally used Asynchronous
Multispin Coding (AMSC). Our overall design sustains a performance of 33.5
picoseconds per spin flip attempt for simulating the three-dimensional
Edwards-Anderson model with parallel tempering, which significantly improves
the performance over existing GPU implementations.Comment: 15 pages, 18 figure
Supplementation of iron alone and combined with vitamins improves haematological status, erythrocyte membrane fluidity and oxidative stress in anaemic pregnant women
Pregnancy is a condition exhibiting increased susceptibility to oxidative stress, and Fe plays a central role in generating harmful oxygen species. The objective of the present study is to investigate the changes in haematological status, oxidative stress and erythrocyte membrane fluidity in anaemic pregnant women after Fe supplementation with and without combined vitamins. The study was a 2 months double-blind, randomised trial. Pregnant women (n 164) were allocated to four groups: group C was the placebo control group; group I was supplemented daily with 60 mg Fe (ferrous sulphate) daily; group IF was supplemented daily with Fe plus 400 µg folic acid; group IM was supplemented daily with Fe plus 2 mg retinol and 1 mg riboflavin, respectively. After the 2-month trial, Hb significantly increased by 15·8, 17·3 and 21·8 g/l, and ferritin by 2·8, 3·6 and 11·0 µg/l, in the I, IF and IM groups compared with placebo. Polarisation (¿) and microviscosity (¿) decreased significantly in other groups compared with placebo, indicating an increase in membrane fluidity. Significant decreases of ¿ and ¿ values compared with group C were 0·033 and 0·959 for group I, 0·037 and 1·074 for group IF and 0·064 and 1·865 for group IM, respectively. In addition, significant increases of glutathione peroxidase activities and decreases of malondialdehyde were shown in all treated groups, as well as increases of plasma retinol and urine riboflavin in group IM. The findings show that supplementation with Fe and particularly in combination with vitamins could improve the haematological status as well as oxidative stress and erythrocyte membrane fluidit
μ-Decanedioato-bis[aquabis(1,10-phenanthroline-κ2 N,N′)manganese(II)] dinitrate–sebacic acid–water (1/1/2)
In the title complex, [Mn2(C10H16O4)(C12H8N2)4(H2O)2](NO3)2·C10H18O4·2H2O, the asymmetric unit contains one-half of the centrosymmetric dinuclear complex cation, one uncoordinated water molecule, one-half of a free sebaic acid (decanedioic acid) molecule that is also completed by inversion symmetry, and one disordered nitrate anion [occupancy ratio 0.454 (4):0.544 (6)]. The MnII atoms are each octahedrally surrounded by four N atoms from two 1,10-phenanthroline (phen) ligands, one O atom from one carbonyl group of the bridging sebacate ligand and one O atom of a water molecule. The crystal structure is stabilized by intermolecular O—H⋯O hydrogen bonds
Pathogen spectrum and immunotherapy in patients with anti-IFN-γ autoantibodies: A multicenter retrospective study and systematic review
BackgroundAnti-interferon-γ autoantibody (AIGA) positivity is an emerging immunodeficiency syndrome closely associated with intracellular infection in individuals without human immunodeficiency virus (HIV). However, the information on epidemiology, pathogen spectrum, and immunotherapy among these patients lack a systematic description of large data.MethodsThis systematic literature review and multicenter retrospective study aimed to describe the pathogen spectrum and review treatment strategies among patients with AIGA positivity.ResultsWe included 810 HIV-negative patients with AIGA positivity infected with one or more intracellular pathogens. Excluding four teenagers, all the patients were adults. The most common pathogen was nontuberculous mycobacteria (NTM) (676/810, 83.5%). A total of 765 NTM isolates were identified in 676 patients with NTM, including 342 (44.7%) rapid-grower mycobacteria, 273 (35.7%) slow-grower mycobacteria, and 150 (19.6%) unidentified NTM subtype. Even with long-term and intensive antimicrobial treatments, 42.6% of patients with AIGA positivity had recurrence and/or persistent infection. Sixty-seven patients underwent immunoregulatory or immunosuppressive therapy, and most (60) achieved remission. The most common treatment strategy was rituximab (27/67, 40.3%) and cyclophosphamide (22/67, 32.8%), followed by cyclophosphamide combined with glucocorticoids (8/67, 11.9%).ConclusionsIntracellular pathogen was the most common infection in patients with AIGA positivity. The predominant infection phenotypes were NTM, varicella-zoster virus, Talaromyces marneffei, and Salmonella spp., with or without other opportunistic infections. AIGA immunotherapy, including rituximab or cyclophosphamide, has yielded good preliminary results in some cases
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