1,266 research outputs found
Pressure effects on charge, spin, and metal-insulator transitions in narrow bandwidth manganite PrCaMnO
Pressure effects on the charge and spin states and the relation between the
ferromagnetic and metallic states were explored on the small bandwidth
manganite PrCaMnO (x = 0.25, 0.3, 0.35). Under pressure,
the charge ordering state is suppressed and a ferromagnetic metallic state is
induced in all three samples. The metal-insulator transition temperature
(T) increases with pressure below a critical point P*, above which
T decreases and the material becomes insulating as at the ambient
pressure. The e electron bandwidth and/or band-filling mediate the
pressure effects on the metal-insulator transition and the magnetic transition.
In the small bandwidth and low doping concentration compound (x = 0.25), the
T and Curie temperature (T) change with pressure in a reverse way
and do not couple under pressure. In the x = 0.3 compound, the relation of
T and T shows a critical behavior: They are coupled in the range
of 0.8-5 GPa and decoupled outside of this range. In the x = 0.35
compound, T and T are coupled in the measured pressure range where
a ferromagnetic state is present
Competition of IL-1 and IL-1ra determines lymphocyte response to delayed stimulation with PHA.
BACKGROUND: Human peripheral blood mononuclear cells (PBMC) left in microcultures for 24h without mitogen do not respond to subsequent stimulation with PHA. They regain reactivity if the native culture medium is absorbed with other party lymphocytes or partially replaced with the medium from a PHA-stimulated culture. The observations suggest that, during the incubation, some inhibitory agent had accumulated in the culture medium. AIM: The study was performed to determine the nature of the observed phenomenon in respect of the possible role of monocytes and their products IL-1 and IL-1 receptor antagonist (IL-1ra), and to test for immunodiagnostic purposes the significance of quantifying the lymphocyte response to delayed stimulation with PHA in patients suffering from inflammatory prosesses. METHODS: Lymphocyte response to delayed stimulation with PHA, calculated as the lymphocyte-monokine interaction (LM) index, was determined in the microcultures of PBMC isolated from the blood of healthy donors or of patients with acute tonsilitis. The values of LM indices were compared with the ratios of IL-1ra/IL-1beta concentration estimated by enzyme-linked immunosorbent assay method in the culture supernatants. The influences of exogenous IL-1beta, IL-1ra, anti-IL1ra antibodies and antibiotic cefaclor on the monokine concentrations and on the values of LM index were tested. RESULTS AND CONCLUSIONS: The results show that the level of lymphocyte response to delayed stimulation with PHA (LM index) is inversely proportional to the ratio of IL-1ra/IL-1beta concentration in the culture. The low LM values at high IL-1ra/IL-1beta ratios in PBMC cultures from healthy donors, reversed proportions found in patients' PBMC (acute tonsilitis), and the cefaclor-induced reduction of LM value with correlated increase of the IL-1ra/IL-1beta ratio suggest that the LM assay may prove to be useful for immunodiagnostic purposes
Quantization of time and the big bang via scale-invariant loop gravity
Acknowledgements The authors are grateful to Y. Adamu and D. Rodrigues for discussions and to the Carnegie Trust and Cruickshank Trust in Scotland for financial support.Peer reviewedPublisher PD
On-site early-warning system for bishkek (Kyrgyzstan)
<p>In this work, the development of an on-site early warning system for Bishkek (Kyrgyzstan) is outlined. Several low cost sensors equipped with MEMS accelerometers are installed in eight buildings distributed within the urban area. The different sensing units communicate each other via wireless links and the seismic data are streamed in real-time to the data center using internet. Since each single sensing unit has computing capabilities, software for data processing can be installed to perform decentralized actions. In particular, each sensing unit can perform event detection task and run software for on-site early warning. If a description for the vulnerability of the building is uploaded in the sensing unit, this piece of information can be exploited to introduce the expected probability of damage in the early-warning protocol customized for a specific structure.</p
Electronic structure of the (111) and (-1-1-1) surfaces of cubic BN: A local-density-functional ab initio study
We present ab initio local-density-functional electronic structure
calculations for the (111) and (-1-1-1) surfaces of cubic BN. The energetically
stable reconstructions, namely the N adatom, N3 triangle models on the (111),
the (2x1), boron and nitrogen triangle patterns on the (-1-1-1) surface are
investigated. Band structure and properties of the surface states are discussed
in detail.Comment: 8 pages, 12 figure
Signal transducer and activator of transcription-5 mediates neuronal apoptosis induced by inhibition of Rac GTPase activity.
In several neuronal cell types, the small GTPase Rac is essential for survival. We have shown previously that the Rho family GTPase inhibitor Clostridium difficile toxin B (ToxB) induces apoptosis in primary rat cerebellar granule neurons (CGNs) principally via inhibition of Rac GTPase function. In the present study, incubation with ToxB activated a proapoptotic Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, and a pan-JAK inhibitor protected CGNs from Rac inhibition. STAT1 expression was induced by ToxB; however, CGNs from STAT1 knock-out mice succumbed to ToxB-induced apoptosis as readily as wild-type CGNs. STAT3 displayed enhanced tyrosine phosphorylation following treatment with ToxB, and a reputed inhibitor of STAT3, cucurbitacin (JSI-124), reduced CGN apoptosis. Unexpectedly, JSI-124 failed to block STAT3 phosphorylation, and CGNs were not protected from ToxB by other known STAT3 inhibitors. In contrast, STAT5A tyrosine phosphorylation induced by ToxB was suppressed by JSI-124. In addition, roscovitine similarly inhibited STAT5A phosphorylation and protected CGNs from ToxB-induced apoptosis. Consistent with these results, adenoviral infection with a dominant negative STAT5 mutant, but not wild-type STAT5, significantly decreased ToxB-induced apoptosis of CGNs. Finally, chromatin immunoprecipitation with a STAT5 antibody revealed increased STAT5 binding to the promoter region of prosurvival Bcl-xL. STAT5 was recruited to the Bcl-xL promoter region in a ToxB-dependent manner, and this DNA binding preceded Bcl-xL down-regulation, suggesting transcriptional repression. These data indicate that a novel JAK/STAT5 proapoptotic pathway significantly contributes to neuronal apoptosis induced by the inhibition of Rac GTPase
Molecular neuroscience at its "high": bibliometric analysis of the most cited papers on endocannabinoid system, cannabis and cannabinoids
Background Cannabis, cannabinoids and endocannabinoids are heavily investigated topics with many articles published every year. We aimed to identify the 100 most cited manuscripts among the vast literature and analyze their contents
Using H-alpha Morphology and Surface Brightness Fluctuations to Age-Date Star Clusters in M83
We use new WFC3 observations of the nearby grand design spiral galaxy M83 to
develop two independent methods for estimating the ages of young star clusters.
The first method uses the physical extent and morphology of Halpha emission to
estimate the ages of clusters younger than tau ~10 Myr. It is based on the
simple premise that the gas in very young (tau < few Myr) clusters is largely
coincident with the cluster stars, is in a small, ring-like structure
surrounding the stars in slightly older clusters (e.g., tau ~5 Myr), and is in
a larger ring-like bubble for still older clusters (i.e., ~5-10 Myr). The
second method is based on an observed relation between pixel-to-pixel flux
variations within clusters and their ages. This method relies on the fact that
the brightest individual stars in a cluster are most prominent at ages around
10 Myr, and fall below the detection limit (i.e., M_V < -3.5) for ages older
than about 100 Myr. These two methods are the basis for a new morphological
classification system which can be used to estimate the ages of star clusters
based on their appearance. We compare previous age estimates of clusters in M83
determined from fitting UBVI Halpha measurements using predictions from stellar
evolutionary models with our new morphological categories and find good
agreement at the ~95% level. The scatter within categories is ~0.1 dex in log
tau for young clusters (10 Myr) clusters. A
by-product of this study is the identification of 22 "single-star" HII regions
in M83, with central stars having ages ~4 Myr.Comment: 33 pages, 10 figures, 3 tables; published in March Ap
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