2,530 research outputs found
Two-dimensional models of hydrodynamical accretion flows into black holes
We present a systematic numerical study of two-dimensional axisymmetric
accretion flows around black holes. The flows have no radiative cooling and are
treated in the framework of the hydrodynamical approximation. The models
calculated in this study cover the large range of the relevant parameter space.
There are four types of flows, determined by the values of the viscosity
parameter and the adiabatic index : convective flows,
large-scale circulations, pure inflows and bipolar outflows. Thermal conduction
introduces significant changes to the solutions, but does not create a new flow
type. Convective accretion flows and flows with large-scale circulations have
significant outward-directed energy fluxes, which have important implications
for the spectra and luminosities of accreting black holes.Comment: 43 pages, 23 figures, submitted to Ap
Novel Treatments and Technologies Applied to the Cure of Neuroblastoma
Neuroblastoma (NB) is the most common extracranial solid tumour in childhood, accounting for approximately 15% of all cancer-related deaths in the paediatric population1. It is
characterised by heterogeneous clinical behaviour in neonates and often adverse outcomes in toddlers. The overall survival of children with high-risk disease is around 40–50% despite the aggressive
treatment protocols consisting of intensive chemotherapy, surgery, radiation therapy and hematopoietic stem cell transplantation2,3. There is an ongoing research effort to increase NB’s cellular and
molecular biology knowledge to translate essential findings into novel treatment strategies. This
review aims to address new therapeutic modalities emerging from preclinical studies offering a
unique translational opportunity for NB treatment
Radiative lifetime measurements of rubidium Rydberg states
We have measured the radiative lifetimes of ns, np and nd Rydberg states of
rubidium in the range 28 < n < 45. To enable long-lived states to be measured,
our experiment uses slow-moving Rb atoms in a magneto-optical trap (MOT). Two
experimental techniques have been adopted to reduce random and systematic
errors. First, a narrow-bandwidth pulsed laser is used to excite the target
Rydberg state, resulting in minimal shot-to-shot variation in the initial state
population. Second, we monitor the target state population as a function of
time delay from the laser pulse using a short-duration, millimetre-wave pulse
that is resonant with a one- or two-photon transition. We then selectively
field ionize the monitor state, and detect the resulting electrons with a
micro-channel plate. This signal is an accurate mirror of the target state
population, and is uncontaminated by contributions from other states which are
populated by black body radiation. Our results are generally consistent with
other recent experimental results obtained using a less sensitive method, and
are also in excellent agreement with theory.Comment: 27 pages,6 figure
Domain walls without cosmological constant in higher order gravity
We consider a class of higher order corrections with arbitrary power of
the curvature tensor to the standard gravity action in arbitrary space-time
dimension . The corrections are in the form of Euler densities and are
unique at each and . We present a generating functional and an explicit
form of the corresponding conserved energy-momentum tensors. The case of
conformally flat metrics is discussed in detail. We show that this class of
corrections allows for domain wall solutions since, despite the presence of
higher powers of the curvature tensor, the singularity structure at the wall is
of the same type as in the standard gravity. However, models with higher order
corrections have larger set of domain wall solutions and the existence of these
solutions no longer depends on the presence of cosmological constants. We find
for example that the Randall-Sundrum scenario can be realized without any need
for bulk and/or brane cosmological constant.Comment: latex, 10 pages, introduction extended, references added, typos
correcte
Prospective unmasked randomized evaluation of the iStent inject (®) versus two ocular hypotensive agents in patients with primary open-angle glaucoma.
PURPOSE: The purpose of this study was to compare outcomes of subjects with open-angle glaucoma (OAG) not controlled on one medication who underwent either implantation of two iStent inject (®) trabecular micro-bypass devices or received medical therapy consisting of a fixed combination of latanoprost/timolol.
PATIENTS AND METHODS: Of 192 subjects who qualified for the study and were enrolled, 94 were randomized to surgery with implantation of two iStent inject(®) devices in the treated eye and 98 to receive medical therapy.
RESULTS: At the month 12 visit, 94.7% of eyes (89/94) in the stent group reported an unmedicated intraocular pressure (IOP) reduction of ≥20% versus baseline unmedicated IOP, and 91.8% of eyes (88/98) in the medical therapy group reported an IOP reduction ≥20% versus baseline unmedicated IOP. A 17.5% between-group treatment difference in favor of the iStent inject group was statistically significant (P=0.02) at the ≥50% level of IOP reduction. An IOP ≤18 mmHg was reported in 92.6% of eyes (87/94) in the iStent inject group and 89.8% of eyes (88/98) in the medical therapy group. Mean (standard deviation) IOP decreases from screening of 8.1 (2.6) mmHg and 7.3 (2.2) mmHg were reported in the iStent inject and medical therapy groups, respectively. A high safety profile was also noted in this study in both the iStent inject and medical therapy groups, as measured by stable best corrected visual acuity, cup-to-disc ratio, and adverse events.
CONCLUSION: These data show that the use of iStent inject is at least as effective as two medications, with the clinical benefit of reducing medication burden and assuring continuous treatment with full compliance to implant therapy as well as having a highly favorable safety profile
Classical and novel TSPO ligands for the mitochondrial TSPO can modulate nuclear gene expression: Implications for mitochondrial retrograde signaling
It is known that knockdown of the mitochondrial 18 kDa translocator protein (TSPO) as well as TSPO ligands modulate various functions, including functions related to cancer. To study the ability of TSPO to regulate gene expression regarding such functions, we applied microarray analysis of gene expression to U118MG glioblastoma cells. Within 15 min, the classical TSPO ligand PK 11195 induced changes in expression of immediate early genes and transcription factors. These changes also included gene products that are part of the canonical pathway serving to modulate general gene expression. These changes are in accord with real-time, reverse transcriptase (RT) PCR. At the time points of 15, 30, 45, and 60 min, as well as 3 and 24 h of PK 11195 exposure, the functions associated with the changes in gene expression in these glioblastoma cells covered well known TSPO functions. These functions included cell viability, proliferation, differentiation, adhesion, migration, tumorigenesis, and angiogenesis. This was corroborated microscopically for cell migration, cell accumulation, adhesion, and neuronal differentiation. Changes in gene expression at 24 h of PK 11195 exposure were related to downregulation of tumorigenesis and upregulation of programmed cell death. In the vehicle treated as well as PK 11195 exposed cell cultures, our triple labeling showed intense TSPO labeling in the mitochondria but no TSPO signal in the cell nuclei. Thus, mitochondrial TSPO appears to be part of the mitochondria-to-nucleus signaling pathway for modulation of nuclear gene expression. The novel TSPO ligand 2-Cl-MGV-1 appeared to be very specific regarding modulation of gene expression of immediate early genes and transcription factors
Equation of State for Helium-4 from Microphysics
We compute the free energy of helium-4 near the lambda transition based on an
exact renormalization-group equation. An approximate solution permits the
determination of universal and nonuniversal thermodynamic properties starting
from the microphysics of the two-particle interactions. The method does not
suffer from infrared divergences. The critical chemical potential agrees with
experiment. This supports a specific formulation of the functional integral
that we have proposed recently. Our results for the equation of state reproduce
the observed qualitative behavior. Despite certain quantitative shortcomings of
our approximation, this demonstrates that ab initio calculations for collective
phenomena become possible by modern renormalization-group methods.Comment: 9 pages, 6 figures, revtex updated version, journal referenc
Antibacterial, antioxidant and anti-proliferative properties and zinc content of five south Portugal herbs
Context: Crataegus monogyna L. (Rosaceae) (CM), Equisetum telmateia L. (Equisataceae) (ET), Geranium purpureum Vil. (Geraniaceae) (GP), Mentha suaveolens Ehrh. (Lamiaceae) (MS), and Lavandula stoechas L. spp. luisieri (Lamiaceae) (LS) are all medicinal. Objective: To evaluate the antioxidant, antiproliferative and antimicrobial activities of plant extracts and quantify individual phenolics and zinc. Material and methods: Aerial part extracts were prepared with water (W), ethanol (E) and an 80% mixture (80EW). Antioxidant activity was measured with TAA, FRAP and RP methods. Phenolics were quantified with a HPLC. Zinc was quantified using voltammetry. Antibacterial activity (after 48 h) was tested using Enterococcus faecalis, Bacillus cereus, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Listeria monocytogenes. Antiproliferative activity (after 24 h) was tested using HEP G2 cells and fibroblasts. Results: Solvents influenced results; the best were E and 80EW. GP had the highest antioxidant activity (TAA and FRAP of 536.90mg AAE/g dw and 783.48mg TE/g dw, respectively). CM had the highest zinc concentration (37.21 mg/kg) and phenolic variety, with neochlorogenic acid as the most abundant (92.91 mg/100 g dw). LS was rich in rosmarinic acid (301.71 mg/100 g dw). GP and LS inhibited the most microorganisms: B. cereus, E. coli and S. aureus. GP also inhibited E. faecalis. CM had the lowest MIC: 5830 mu g/mL. The antibacterial activity is explained by the phenolics present. LS and CM showed the most significant anti-proliferative activity, which is explained by their zinc content. Conclusion: The most promising plants for further studies are CM, LS and GP.FCT, Fundacao para a Ciencia e a Tecnologia of Portugal [SFRH/BSA/139/2014
Statistical equilibrium of silicon in the solar atmosphere
The statistical equilibrium of neutral and ionised silicon in the solar
photosphere is investigated. Line formation is discussed and the solar silicon
abundance determined. High-resolution solar spectra were used to determine
solar values by comparison with Si line synthesis
based on LTE and NLTE level populations. The results will be used in a
forthcoming paper for differential abundance analyses of metal-poor stars. A
detailed analysis of silicon line spectra leads to setting up realistic model
atoms, which are exposed to interactions in plane-parallel solar atmospheric
models. The resulting departure coefficients are entered into a line-by-line
analysis of the visible and near-infrared solar silicon spectrum. The
statistical equilibrium of \ion{Si}{i} turns out to depend marginally on
bound-free interaction processes, both radiative and collisional. Bound-bound
interaction processes do not play a significant role either, except for
hydrogen collisions, which have to be chosen adequately for fitting the cores
of the near-infrared lines. Except for some near-infrared lines, the NLTE
influence on the abundances is weak. Taking the deviations from LTE in silicon
into account, it is possible to calculate the ionisation equilibrium from
neutral and ionised lines. The solar abundance based on the experimental
-values of Garz corrected for the Becker et al.'s measurement is . Combined with an extended line sample with selected NIST -values, the
solar abundance is , with a nearly perfect ionisation
equilibrium of \Delta\log\epsilon_\odot(\ion{Si}{ii}/\ion{Si}{i}) = -0.01.Comment: 13pages 10 figures. A&A acceptte
Theoretical investigation on possible operation of a 140 GHz 1 MW gyrotron at 175 GHz for CTS plasma diagnostics at W7-X
- …