583 research outputs found
Properties of neutral mesons in a hot and magnetized quark matter
The properties of non-interacting and mesons are studied
at finite temperature, chemical potential and in the presence of a constant
magnetic field. To do this, the energy dispersion relations of these particles,
including nontrivial form factors, are derived using a derivative expansion of
the effective action of a two-flavor, hot and magnetized Nambu--Jona-Lasinio
(NJL) model up to second order. The temperature dependence of the pole and
screening masses as well as the directional refraction indices of magnetized
neutral mesons are explored for fixed magnetic fields and chemical potentials.
It is shown that, because of the explicit breaking of the Lorentz invariance by
the magnetic field, the refraction index and the screening mass of neutral
mesons exhibit a certain anisotropy in the transverse and longitudinal
directions with respect to the direction of the external magnetic field. In
contrast to their longitudinal refraction indices, the transverse indices of
the neutral mesons are larger than unity.Comment: V1: 26 pages, 15 figures; V2: Discussions improved, references added.
Version accepted for publication in PR
BLUF Domain Function Does Not Require a Metastable Radical Intermediate State
BLUF
(blue light using flavin) domain proteins are an important
family of blue light-sensing proteins which control a wide variety
of functions in cells. The primary light-activated step in the BLUF
domain is not yet established. A number of experimental and theoretical
studies points to a role for photoinduced electron transfer (PET)
between a highly conserved tyrosine and the flavin chromophore to
form a radical intermediate state. Here we investigate the role of
PET in three different BLUF proteins, using ultrafast broadband transient
infrared spectroscopy. We characterize and identify infrared active
marker modes for excited and ground state species and use them to
record photochemical dynamics in the proteins. We also generate mutants
which unambiguously show PET and, through isotope labeling of the
protein and the chromophore, are able to assign modes characteristic
of both flavin and protein radical states. We find that these radical
intermediates are not observed in two of the three BLUF domains studied,
casting doubt on the importance of the formation of a population of
radical intermediates in the BLUF photocycle. Further, unnatural amino
acid mutagenesis is used to replace the conserved tyrosine with fluorotyrosines,
thus modifying the driving force for the proposed electron transfer
reaction; the rate changes observed are also not consistent with a
PET mechanism. Thus, while intermediates of PET reactions can be observed
in BLUF proteins they are not correlated with photoactivity, suggesting
that radical intermediates are not central to their operation. Alternative
nonradical pathways including a ketoâenol tautomerization induced
by electronic excitation of the flavin ring are considered
Alteration in CD8+ T cell subsets in enterovirus-infected patients: An alarming factor for type 1 diabetes mellitus
Type 1 diabetes is a multi-factorial disease that can develop due to the combination of genetic and environmental factors. Viruses, particularly enteroviruses, are major environmental candidates in the pathogenesis of type 1 diabetes, even though the mechanisms of pathogenicity of these viruses and their effects on the immune system have not been understood very well yet. Previous studies show that any imbalance in the population of different lymphocyte subsets could develop autoimmune diseases. Our theory is that enteroviral infection causes an impairment in the distribution of lymphocyte subtypes and consequently results in the diabetes onset in some individuals. Therefore, in this project, we evaluated the distribution of T CD8+ lymphocytes and their subsets in type 1 diabetes patients. This study was conducted to investigate the relationship between enteroviral infection and type 1 diabetes mellitus in an Iranian population, and suggestion a predicting approach for susceptible subjects
Therapeutic potentials of curcumin in the treatment of glioblstoma
Glioblastoma multiforme (GBM), a greatly aggressive malignancy of the brain, is correlated with a poor prognosis and low rate of survival. Up to now, chemotherapy and radiation therapy after surgical approaches have been the treatments increasing the survival rates. The low efficacy of mentioned therapies as well as their side-effects has forced researchers to explore an appropriate alternative or complementary treatment for glioblastoma. In experimental models, it has been shown that curcumin has therapeutic potentials to fight against GBM. Given that curcumin has pharmacological effects against cancer stem cells, as major causes of resistance to therapy in glioblastoma cells. Moreover, it has been showed that curcumin exerts its therapeutic effects on GBM cells via affecting on apoptosis, oxidant system, and inflammatory pathways. Curcumin would possess a synergistic impact with chemotherapeutic agents. Herein, we summarized the current findings on curcumin as therapeutic agent in the treatment of GBM. Ă© 2020 Elsevier Masson SA
The translocator protein (TSPO) is prodromal to mitophagy loss in neurotoxicity
Dysfunctional mitochondria characterise Parkinson's Disease (PD). Uncovering etiological molecules, which harm the homeostasis of mitochondria in response to pathological cues, is therefore pivotal to inform early diagnosis and therapy in the condition, especially in its idiopathic forms. This study proposes the 18 kDa Translocator Protein (TSPO) to be one of those. Both in vitro and in vivo data show that neurotoxins, which phenotypically mimic PD, increase TSPO to enhance cellular redox-stress, susceptibility to dopamine-induced cell death, and repression of ubiquitin-dependent mitophagy. TSPO amplifies the extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) signalling, forming positive feedback, which represses the transcription factor EB (TFEB) and the controlled production of lysosomes. Finally, genetic variances in the transcriptome confirm that TSPO is required to alter the autophagy-lysosomal pathway during neurotoxicity
The GstLAL Search Analysis Methods for Compact Binary Mergers in Advanced LIGO's Second and Advanced Virgo's First Observing Runs
After their successful first observing run (September 12, 2015 - January 12, 2016), the Advanced LIGO detectors were upgraded to increase their sensitivity for the second observing run (November 30, 2016 - August 26, 2017). The Advanced Virgo detector joined the second observing run on August 1, 2017. We discuss the updates that happened during this period in the GstLAL-based inspiral pipeline, which is used to detect gravitational waves from the coalescence of compact binaries both in low latency and an offline configuration. These updates include deployment of a zero-latency whitening filter to reduce the over-all latency of the pipeline by up to 32 seconds, incorporation of the Virgo data stream in the analysis, introduction of a single-detector search to analyze data from the periods when only one of the detectors is running, addition of new parameters to the likelihood ratio ranking statistic, increase in the parameter space of the search, and introduction of a template mass-dependent glitch-excision thresholding method
Comparison of anthro-metabolic indicators for predicting the risk of metabolic syndrome in the elderly population: Bushehr Elderly Health (BEH) program
Background
Metabolic syndrome (MetS) is a cluster metabolic disorder that includes central obesity, insulin resistance, hypertension, and dyslipidemia, and is highly associated with an increased risk of developing non-communicable diseases (NCDs). This study aimed to compare the reliability of anthro-metabolic indices [visceral adiposity index (VAI), body roundness index (BRI), and a body shape index (BSI), body adiposity index (BAI), lipid accumulation product (LAP), waist to hip ratio, and waist to height ratio] in predicting MetS in Iranian older people.
Methods
This cross-sectional study was conducted based on the data of 2426 adults aged â„60 years that participated in the second stage of the Bushehr Elderly Health (BEH) program, a population-based prospective cohort study being conducted in Bushehr, Iran. MetS was defined based on the revised National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. The receiver operating characteristic (ROC) curve analysis was used to assess predictive performance of anthro-metabolic indices and determine optimal cutoff values. Logistic regression analysis was applied to determine the associations between MetS and indices.
Results
2426 subjects (48.1% men) with meanâ±âSD age of 69.34â±â6.40 years were included in the study. According to ATP III criteria, 34.8% of men and 65.2% of women had MetS (Pâ<â0.001). Of the seven examined indices, the AUCs of VAI and LAP in both genders were higher than AUCs of other anthro-metabolic indices. Also, in general population, VAI and LAP had the greatest predictive power for MetS with AUC 0.87(0.86â0.89) and 0.87(0.85â0.88), respectively. The lowest AUC in total population belonged to BSI with the area under the curve of 0.60(0.58â0.62). After adjusting for potential confounders (e.g. age, sex, education, physical activity, current smoking) in the logistic regression model, the highest OR in the total population was observed for VAI and LAP, which was 16.63 (13.31â20.79) and 12.56 (10.23â15.43) respectively. The lowest OR for MetS was 1.93(1.61â2.30) for BSI.
Conclusion
This study indicated that both VAI and LAP are the most valuable indices among the anthro-metabolic indices to identify MetS among the elderly in both genders. So, they could be used as proper assessment tools for MetS in clinical practice. However, the cost-benefit of these indices compared to the ATP III criteria need further studies
Medical podcasting in Iran; pilot, implementation and attitude evaluation
Podcasting has become a popular means of transferring knowledge in higher education through making lecture contents available to students at their convenience. Accessing courses on media players provides students with enhanced learning opportunities. Development of teaching methods able to cope with ever-changing nature of medicine is crucial to train the millennium students. Pharmacology education in Tehran University of Medical Sciences has been based on lectures so far; our aim was to implement a pilot study to evaluate the advantages and disadvantages of offering the course contents as podcasts as well as evaluating whether such program can be feasible in our educational program. 46% of students downloaded the podcast according to our download center. 48% favored usage of both internet and DVD-ROM concurrently. Overall 96% of students perceived that podcasting had a positive impact on their learning in pharmacology course. Our results indicate that most of attendants proposed the positive yields of podcasting despite low usage of it, mainly as a pre-class preparing tool.publisher versio
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGOâs first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
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