2,642 research outputs found
Recent Progress in Neutron Star Theory
This review contains chapters discussing: Energy density fluctionals of
nuclear matter, Many-body theory of nucleon matter, Hadronic and quark matter,
Mixtures of phases in dense matter, Neutron star observations and predictions.Comment: 33 pages +13 figs., Ann. Rev. Nucl. & Part. Science, 200
Relativistic Mean-Field Theory Equation of State of Neutron Star Matter and a Maxwellian Phase Transition to Strange Quark Matter
The equation of state of neutron star matter is examined in terms of the
relativistic mean-field theory, including a scalar-isovector -meson
effective field. The constants of the theory are determined numerically so that
the empirically known characteristics of symmetric nuclear matter are
reproduced at the saturation density. The thermodynamic characteristics of both
asymmetric nucleonic matter and -equilibrium hadron-electron
-plasmas are studied. Assuming that the transition to strange quark matter
is an ordinary first-order phase transition described by Maxwell's rule, a
detailed study is made of the variations in the parameters of the phase
transition owing to the presence of a -meson field. The quark phase is
described using an improved version of the bag model, in which interactions
between quarks are accounted for in a one-gluon exchange approximation. The
characteristics of the phase transition are determined for various values of
the bag parameter within the range and it is shown
that including a -meson field leads to a reduction in the phase
transition pressure and in the concentrations and at
the phase transition point.Comment: 17 pages, 8 figure
A generalization of a theorem of Bor
Abstract In this paper, a general theorem concerning absolute matrix summability is established by applying the concepts of almost increasing and δ-quasi-monotone sequences
The novel mu-opioid antagonist, GSK1521498, reduces ethanol consumption in C57BL/6J mice.
RATIONALE
Using the drinking-in-the-dark (DID) model, we compared the effects of a novel mu-opioid receptor antagonist, GSK1521498, with naltrexone, a licensed treatment of alcohol dependence, on ethanol consumption in mice.
OBJECTIVE
We test the ability of GSK1521498 to reduce alcohol consumption and compare its intrinsic efficacy to that of naltrexone by comparing the two drugs at doses matched for equivalent receptor occupancy.
METHODS
Thirty-six C57BL/6J mice were tested in a DID procedure. In 2-day cycles, animals experienced one baseline, injection-free session, and one test session when they received two injections, one of test drug and one placebo. All animals received GSK1521498 (0, 0.1, 1 and 3 mg/kg, i.p., 30 min pre-treatment) and naltrexone (0, 0.1, 1 and 3 mg/kg, s.c. 10 min pre-treatment) in a cross-over design. Receptor occupancies following the same doses were determined ex vivo in separate groups by autoradiography, using [3H]DAMGO. Binding in the region of interest was measured integrally by computer-assisted microdensitometry and corrected for non-specific binding.
RESULTS
Both GSK1521498 and naltrexone dose-dependently decreased ethanol consumption. When drug doses were matched for 70-75 % receptor occupancy, GSK1521498 3 mg/kg, i.p., caused a 2.5-fold greater reduction in alcohol consumption than naltrexone 0.1 mg/kg, s.c. Both GSK1521498 and naltrexone significantly reduced sucrose consumption at a dose of 1 mg/kg but not 0.1 mg/kg. In a test of conditioned taste aversion, GSK1521498 (3 mg/kg) reduced sucrose consumption 24 h following exposure to a conditioning injection.
CONCLUSIONS
Both opioid receptor antagonists reduced alcohol consumption but GK1521498 has higher intrinsic efficacy than naltrexone
Design of Experiments for Screening
The aim of this paper is to review methods of designing screening
experiments, ranging from designs originally developed for physical experiments
to those especially tailored to experiments on numerical models. The strengths
and weaknesses of the various designs for screening variables in numerical
models are discussed. First, classes of factorial designs for experiments to
estimate main effects and interactions through a linear statistical model are
described, specifically regular and nonregular fractional factorial designs,
supersaturated designs and systematic fractional replicate designs. Generic
issues of aliasing, bias and cancellation of factorial effects are discussed.
Second, group screening experiments are considered including factorial group
screening and sequential bifurcation. Third, random sampling plans are
discussed including Latin hypercube sampling and sampling plans to estimate
elementary effects. Fourth, a variety of modelling methods commonly employed
with screening designs are briefly described. Finally, a novel study
demonstrates six screening methods on two frequently-used exemplars, and their
performances are compared
The Minimal Scale Invariant Extension of the Standard Model
We perform a systematic analysis of an extension of the Standard Model that
includes a complex singlet scalar field and is scale invariant at the tree
level. We call such a model the Minimal Scale Invariant extension of the
Standard Model (MSISM). The tree-level scale invariance of the model is
explicitly broken by quantum corrections, which can trigger electroweak
symmetry breaking and potentially provide a mechanism for solving the gauge
hierarchy problem. Even though the scale invariant Standard Model is not a
realistic scenario, the addition of a complex singlet scalar field may result
in a perturbative and phenomenologically viable theory. We present a complete
classification of the flat directions which may occur in the classical scalar
potential of the MSISM. After calculating the one-loop effective potential of
the MSISM, we investigate a number of representative scenarios and determine
their scalar boson mass spectra, as well as their perturbatively allowed
parameter space compatible with electroweak precision data. We discuss the
phenomenological implications of these scenarios, in particular, whether they
realize explicit or spontaneous CP violation, neutrino masses or provide dark
matter candidates. In particular, we find a new minimal scale-invariant model
of maximal spontaneous CP violation which can stay perturbative up to
Planck-mass energy scales, without introducing an unnaturally large hierarchy
in the scalar-potential couplings.Comment: 71 pages, 34 eps figures, numerical error corrected, clarifying
comments adde
Power-Law Scaling in the Brain Surface Electric Potential
Recent studies have identified broadband phenomena in the electric potentials produced by the brain. We report the finding of power-law scaling in these signals using subdural electrocorticographic recordings from the surface of human cortex. The power spectral density (PSD) of the electric potential has the power-law form from 80 to 500 Hz. This scaling index, , is conserved across subjects, area in the cortex, and local neural activity levels. The shape of the PSD does not change with increases in local cortical activity, but the amplitude, , increases. We observe a “knee” in the spectra at , implying the existence of a characteristic time scale . Below , we explore two-power-law forms of the PSD, and demonstrate that there are activity-related fluctuations in the amplitude of a power-law process lying beneath the rhythms. Finally, we illustrate through simulation how, small-scale, simplified neuronal models could lead to these power-law observations. This suggests a new paradigm of non-oscillatory “asynchronous,” scale-free, changes in cortical potentials, corresponding to changes in mean population-averaged firing rate, to complement the prevalent “synchronous” rhythm-based paradigm
Comparison of three rapid and easy bacterial DNA extraction methods for use with quantitative real-time PCR
The development of fast and easy on-site molecular detection and quantification methods for hazardous microbes on solid surfaces is desirable for several applications where specialised laboratory facilities are absent. The quantification of bacterial contamination necessitates the assessment of the efficiency of the used methodology as a whole, including the preceding steps of sampling and sample processing. We used quantitative real-time polymerase chain reaction (qrtPCR) for Escherichia coli and Staphylococcus aureus to measure the recovery of DNA from defined numbers of bacterial cells that were subjected to three different DNA extraction methods: the QIAamp® DNA Mini Kit, Reischl et al.’s method and FTA® Elute. FTA® Elute significantly showed the highest median DNA extraction efficiency of 76.9% for E. coli and 108.9% for S. aureus. The Reischl et al. method and QIAamp® DNA Mini Kit inhibited the E. coli qrtPCR assay with a 10-fold decrease of detectable DNA. None of the methods inhibited the S. aureus qrtPCR assay. The FTA® Elute applicability was demonstrated with swab samples taken from the International Space Station (ISS) interior. Overall, the FTA® Elute method was found to be the most suitable to selected criteria in terms of rapidity, easiness of use, DNA extraction efficiency, toxicity, and transport and storage conditions
Dealing with Alcohol-related problems in the Night-Time Economy: A Study Protocol for Mapping trends in harm and stakeholder views surrounding local community level interventions
<p>Abstract</p> <p>Background</p> <p>This project will provide a comprehensive investigation into the prevalence of alcohol-related harms and community attitudes in the context of community-based interventions being implemented to reduce harm in two regional centres of Australia. While considerable experimentation and innovation to address these harms has occurred in both Geelong and Newcastle, only limited ad-hoc documentation and analysis has been conducted on changes in the prevalence of harm as a consequence, leaving a considerable gap in terms of a systematic, evidence-based analysis of changes in harm over time and the need for further intervention. Similarly, little evidence has been reported regarding the views of key stakeholder groups, industry, government agencies, patrons or community regarding the need for, and the acceptability of, interventions to reduce harms. This project will aim to provide evidence regarding the impact and acceptability of local initiatives aimed at reducing alcohol-related harms.</p> <p>Methods/Design</p> <p>This study will gather existing police data (assault, property damage and drink driving offences), Emergency Department presentations and Ambulance attendance data. Further, the research team will conduct interviews with licensed venue patrons and collect observational data of licensed venues. Key informant interviews will assess expert knowledge from key industry and government stakeholders, and a community survey will assess community experiences and attitudes towards alcohol-related harm and harm-reduction strategies. Overall, the project will assess: the extent of alcohol-related harm in the context of harm-reduction interventions, and the need for and acceptability of further intervention.</p> <p>Discussion</p> <p>These findings will be used to improve evidence-based practice both nationally and internationally.</p> <p>Ethical Approval</p> <p>This project has been approved by Deakin University HREC.</p
G-CSF Prevents the Progression of Structural Disintegration of White Matter Tracts in Amyotrophic Lateral Sclerosis: A Pilot Trial
Background: The hematopoietic protein Granulocyte-colony stimulating factor (G-CSF) has neuroprotective and regenerative properties. The G-CSF receptor is expressed by motoneurons, and G-CSF protects cultured motoneuronal cells from apoptosis. It therefore appears as an attractive and feasible drug candidate for the treatment of amyotrophic lateral sclerosis (ALS). The current pilot study was performed to determine whether treatment with G-CSF in ALS patients is feasible.Methods: Ten patients with definite ALS were entered into a double-blind, placebo-controlled, randomized trial. Patients received either 10 mu g/kg BW G-CSF or placebo subcutaneously for the first 10 days and from day 20 to 25 of the study. Clinical outcome was assessed by changes in the ALS functional rating scale (ALSFRS), a comprehensive neuropsychological test battery, and by examining hand activities of daily living over the course of the study (100 days). The total number of adverse events (AE) and treatment-related AEs, discontinuation due to treatment-related AEs, laboratory parameters including leukocyte, erythrocyte, and platelet count, as well as vital signs were examined as safety endpoints. Furthermore, we explored potential effects of G-CSF on structural cerebral abnormalities on the basis of voxel-wise statistics of Diffusion Tensor Imaging (DTI), brain volumetry, and voxel-based morphometry.Results: Treatment was well-tolerated. No significant differences were found between groups in clinical tests and brain volumetry from baseline to day 100. However, DTI analysis revealed significant reductions of fractional anisotropy (FA) encompassing diffuse areas of the brain when patients were compared to controls. On longitudinal analysis, the placebo group showed significant greater and more widespread decline in FA than the ALS patients treated with G-CSF.Conclusions: Subcutaneous G-CSF treatment in ALS patients appears as feasible approach. Although exploratory analysis of clinical data showed no significant effect, DTI measurements suggest that the widespread and progressive microstructural neural damage in ALS can be modulated by G-CSF treatment. These findings may carry significant implications for further clinical trials on ALS using growth factors
- …