1,598 research outputs found
Energetics of jets from X-ray binaries
I discuss the energetics of synchrotron-emitting outflows, increasingly found
to be present in many different classes of X-ray binary systems. It is shown
that the outflow is likely to be comparable in power to the integrated X-ray
luminosity, traditionally taken to be an indicator of the global mass-transfer
rate. This is especially found to be the case in the (low/)hard states of black
hole candidate systems. I conclude that jets are extremely important,
energetically and dynamically, for the accretion process in the majority of
known X-ray binary systems.Comment: To be published in `Proceedings of the Third Microquasar Workshop:
Granada Workshop on galactic relativistic jet sources', Eds A. J.
Castro-Tirado, J. Greiner and J. M. Paredes, Astrophysics and Space Science,
in pres
Morphoanatomical and phytochemical studies for the quality control of Neurolaena lobata (L.) R.Br. ex Cass. (Asteraceae)
Neurolaena lobata (L.) R.Br. ex Cass. (Asteraceae)Is a popular folk remedy for in Central America. The plant is of commercial value in Guatemala but so far there is not any monograph to guide regional laboratories on ensuring identity and chemical tests for this species. As identity test we here run macro and micro morphoanatomical studies of the characters of the vegetative organs. We also developed standard chemical tests for quality by both TLC and HPLC for infusions and tinctures of varying alcoholic strength. Their radical scavenging activities in DPPH and NO were also measured. Macro and micro morphoanatomical characters of the vegetative organs present a set of characteristics to facilitate the identification of dry powdered samples of this species. We developed optimal conditions for the TLC and HPLC phytochemical fingerprints of the 4 most common pharmacopoeial liquid herbal preparations from this herbal drug, namely infusion, 70%, 45% and 20% hydroalcoholic tinctures. Our work provides the Latin-American industry with a set of analyses to establish the identity and chemistry of N. lobata samples for quality control purposes. © 2019, Universidad de Santiago de Chile. All rights reserved
Multi-specific calibration of the B isotope proxy in calcareous red algae for pH reconstruction
Calcareous red algae have calcified cell walls constituted by high-Mg calcite or aragonite (Morse et al., 2006). They are considered suitable paleoclimate archives due to their worldwide distribution and their longevity through indeterminate growth (Kamenos et al., 2008). Boron isotopes (δ11B) measured in their calcified thallus are considered a pH proxy (Hemming and Hanson, 1992). In seawater, boron occurs as boric acid and borate ion. Both species are enriched in 11B as pH increases, with boric acid characterized by an enrichment factor of 27‰ compared to borate. The boron isotope proxy theory states that borate is exclusively incorporated in the mineral lattice (Hemming and Hanson, 1992). Therefore, if we measure δ11B in carbonates, we can derive the seawater pH at the time of precipitation. Literature data on δ11B in calcareous red algae are sparse, and the mechanisms of boron incorporation are still poorly known (Piazza et al., 2022). We tested the boron isotope-pH proxy on calcareous red algae grown at 1 m depth close to CO2 seeps off the coasts of Ischia (Italy), and Methana (Greece), which are both characterized by a broad range of natural pH in seawater (from 6.80 ± 0.43 to 8.08 ± 0.07 units). Environmental data characterizing the seawater during the algal growth were extracted from CMEMS products (Marine Copernicus Service Information), or provided by literature. The δ11B values in the algae (δ11Balgae) analysed by Multi Collector Inductively-Coupled Plasma Mass Spectrometry ranged from 22.23‰ to 26.59‰, calibrated over a range of δ11B in aqueous borate (δ11Bborate) extending from 12.68‰ to 18.05‰. A crystallographic control over boron incorporation was shown by the difference in the isotopic composition of carbonate polymorphs, with Mg-calcite enriched in 11B compared to aragonite. Values of δ11Balgae higher than δ11Bborate could be attributed to the up-regulation of the calcifying fluid pH exerted by the algae. We proposed a multi-specific calibration using literature data of boron isotopes in cultured coralline algae combined with our new data on wild-grown specimens, widening the range of pH considered for δ11B calibrations so far. The proposed calibration is particularly useful when experimental calibration is not possible, such as in the fossil record and in the case of ambiguous identifications
Holographic duals of SQCD models in low dimensions
We obtain gravity duals to supersymmetric gauge theories in two and three
spacetime dimensions with unquenched flavor. The supergravity solutions are
generated by a set of color branes wrapping a compact cycle in a Calabi-Yau
threefold, together with another set of flavor branes extended along the
directions orthogonal to the cycle wrapped by the color branes. We construct
supergravity backgrounds which include the backreaction induced by a smeared
set of flavor branes, which act as delocalized dynamical sources of the
different supergravity fields.Comment: 42 pages, 5 figures;v2: typos correcte
Activity of the DNA minor groove cross-linking agent SG2000 (SJG-136) against canine tumours
BACKGROUND: Cancer is the leading cause of death in older dogs and its prevalence is increasing. There is clearly a need to develop more effective anti-cancer drugs in dogs. SG2000 (SJG-136) is a sequence selective DNA minor groove cross-linking agent. Based on its in vitro potency, the spectrum of in vivo and clinical activity against human tumours, and its tolerability in human patients, SG2000 has potential as a novel therapeutic against spontaneously occurring canine malignancies. RESULTS: In vitro cytotoxicity was assessed using SRB and MTT assays, and in vivo activity was assessed using canine tumour xenografts. DNA interstrand cross-linking (ICL) was determined using a modification of the single cell gel electrophoresis (comet) assay. Effects on cell cycle distribution were assessed by flow cytometry and measurement of γ-H2AX by immunofluorescence and immunohistochemistry. SG2000 had a multi-log differential cytotoxic profile against a panel of 12 canine tumour cell lines representing a range of common tumour types in dogs. In the CMeC-1 melanoma cell line, DNA ICLs increased linearly with dose following a 1 h treatment. Peak ICL was achieved within 1 h and no removal was observed over 48 h. A relationship between DNA ICL formation and cytotoxicity was observed across cell lines. The formation of γ-H2AX foci was slow, becoming evident after 4 h and reaching a peak at 24 h. SG2000 exhibited significant anti-tumour activity against two canine melanoma tumour models in vivo. Anti-tumour activity was observed at 0.15 and 0.3 mg/kg given i.v. either once, or weekly x 3. Dose-dependent DNA ICL was observed in tumours (and to a lower level in peripheral blood mononuclear cells) at 2 h and persisted at 24 h. ICL increased following the second and third doses in a repeated dose schedule. At 24 h, dose dependent γ-H2AX foci were more numerous than at 2 h, and greater in tumours than in peripheral blood mononuclear cells. SG2000-induced H2AX phosphorylation measured by immunohistochemistry showed good correspondence, but less sensitivity, than measurement of foci. CONCLUSIONS: SG2000 displayed potent activity in vitro against canine cancer cell lines as a result of the formation and persistence of DNA ICLs. SG2000 also had significant in vivo antitumour activity against canine melanoma xenografts, and the comet and γ-H2AX foci methods were relevant pharmacodynamic assays. The clinical testing of SG2000 against spontaneous canine cancer is warranted. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12917-015-0534-2) contains supplementary material, which is available to authorized users
Holographic Approach to Regge Trajectory and Rotating D5 brane
We study the Regge trajectories of holographic mesons and baryons by
considering rotating strings and D5 brane, which is introduced as the baryon
vertex. Our model is based on the type IIB superstring theory with the
background of asymptotic . This background is dual to a
confining supersymmetric Yang-Mills theory (SYM) with gauge condensate,
, which determines the tension of the linear potential between the quark
and anti-quark. Then the slope of the meson trajectory () is given
by this condensate as at large spin . This
relation is compatible with the other theoretical results and experiments. For
the baryon, we show the importance of spinning baryon vertex to obtain a Regge
slope compatible with the one of and series. In both cases, mesons
and baryons, the trajectories are shifted to large mass side with the same
slope for increasing current quark mass.Comment: 28 pages, 7 figure
Lower prevalence of drug resistance mutations at first-line virological failure to first-line therapy with atripla vs. tenofovirRemtricitabine/lamivudineRefavirenz administered on a multiple tablet therapy
Fixed-dose combination antiretroviral therapy administered as a single-tablet regimen (STR) may improve virologic suppression rates. The effect of STRs on development of resistance when virologic failure occurs on STRs is not known
Recovery of early meteorological records from Extremadura region (SW Iberia): The ''CliPastExtrem'' (v1.0) database
In this work, we provide instrumental meteorological data recovered for the Extremadura region (interior SW Iberia), from 1826 to mid-20th century. Meteorological variables such as air temperature, atmospheric pressure, precipitation, wind direction and humidity, among others, were retrieved. In total, more than 750 000 instrumental data in 157 meteorological series belonging to 131 different locations throughout Extremadura were rescued. It must be noted that daily resolution data constitutes 80% of the database. This great effort of digitization and data collection has been carried out with the aim of contributing to a significant expansion of the length of the databases with meteorological information in this region. Therefore, this database will provide a better understanding of climate variability, trends and extreme events of the Extremadura region
N=1 SQCD-like theories with N_f massive flavors from AdS/CFT and beta functions
We study new supergravity solutions related to large-
supersymmetric gauge field theories with a large number of massive
flavors. We use a recently proposed framework based on configurations with
color D5 branes and a distribution of flavor D5 branes, governed by
a function . Although the system admits many solutions, under
plausible physical assumptions the relevant solution is uniquely determined for
each value of . In the IR region, the solution smoothly
approaches the deformed Maldacena-N\'u\~nez solution. In the UV region it
approaches a linear dilaton solution. For the gauge coupling
function computed holographically is negative definite, in the UV approaching
the NSVZ function with anomalous dimension
(approaching )), and with in
the IR. For , has a UV fixed point at strong coupling,
suggesting the existence of an IR fixed point at a lower value of the coupling.
We argue that the solutions with describe a "Seiberg dual" picture where
flips sign.Comment: 18 pages, 10 figure
Shape-resonant superconductivity in nanofilms: from weak to strong coupling
Ultrathin superconductors of different materials are becoming a powerful
platform to find mechanisms for enhancement of superconductivity, exploiting
shape resonances in different superconducting properties. Here we evaluate the
superconducting gap and its spatial profile, the multiple gap components, and
the chemical potential, of generic superconducting nanofilms, considering the
pairing attraction and its energy scale as tunable parameters, from weak to
strong coupling, at fixed electron density. Superconducting properties are
evaluated at mean field level as a function of the thickness of the nanofilm,
in order to characterize the shape resonances in the superconducting gap. We
find that the most pronounced shape resonances are generated for weakly coupled
superconductors, while approaching the strong coupling regime the shape
resonances are rounded by a mixing of the subbands due to the large energy gaps
extending over large energy scales. Finally, we find that the spatial profile,
transverse to the nanofilm, of the superconducting gap acquires a flat behavior
in the shape resonance region, indicating that a robust and uniform multigap
superconducting state can arise at resonance.Comment: 7 pages, 4 figures. Submitted to the Proceedings of the Superstripes
2016 conferenc
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