1,603 research outputs found
Strange stars at finite temperature
We calculate strange star properties, using large N_c approximation with
built-in chiral symmetry restoration (CSM). We used a relativistic Hartree Fock
mean field approximation method, using a modified Richardson potential with two
scale parameters \Lambda and \Lambda^\prime, to find a new set of equation of
states for strange quark matter. We take the effect of temperature (T) on gluon
mass, in addition to the usual density dependence, and find that the transition
T from hadronic matter to strange matter is 80 MeV. Therefore formation of
strange stars may be the only signal for formation of QGP with asymptotic
freedom and CSM.Comment: To be published in the proceedings of The Third 21COE Symposium, held
at Department of Physics, Waseda University, Tokyo, Japan, September 1-3,
200
Power-law decay in first-order relaxation processes
Starting from a simple definition of stationary regime in first-order
relaxation processes, we obtain that experimental results are to be fitted to a
power-law when approaching the stationary limit. On the basis of this result we
propose a graphical representation that allows the discrimination between
power-law and stretched exponential time decays. Examples of fittings of
magnetic, dielectric and simulated relaxation data support the results.Comment: to appear in Phys. Rev. B; 4 figure
A Bayesian parameter estimation approach to pulsar time-of-arrival analysis
The increasing sensitivities of pulsar timing arrays to ultra-low frequency
(nHz) gravitational waves promises to achieve direct gravitational wave
detection within the next 5-10 years. While there are many parallel efforts
being made in the improvement of telescope sensitivity, the detection of stable
millisecond pulsars and the improvement of the timing software, there are
reasons to believe that the methods used to accurately determine the
time-of-arrival (TOA) of pulses from radio pulsars can be improved upon. More
specifically, the determination of the uncertainties on these TOAs, which
strongly affect the ability to detect GWs through pulsar timing, may be
unreliable. We propose two Bayesian methods for the generation of pulsar TOAs
starting from pulsar "search-mode" data and pre-folded data. These methods are
applied to simulated toy-model examples and in this initial work we focus on
the issue of uncertainties in the folding period. The final results of our
analysis are expressed in the form of posterior probability distributions on
the signal parameters (including the TOA) from a single observation.Comment: 16 pages, 4 figure
Multiferroic behavior in the new double-perovskite LuMnCoO
We present a new member of the multiferroic oxides, LuMnCoO, which we
have investigated using X-ray diffraction, neutron diffraction, specific heat,
magnetization, electric polarization, and dielectric constant measurements.
This material possesses an electric polarization strongly coupled to a net
magnetization below 35 K, despite the antiferromagnetic ordering of the Mn and Co spins in an configuration along the c-direction. We discuss the magnetic order
in terms of a condensation of domain boundaries between and
ferromagnetic domains, with each domain boundary
producing a net electric polarization due to spatial inversion symmetry
breaking. In an applied magnetic field the domain boundaries slide, controlling
the size of the net magnetization, electric polarization, and magnetoelectric
coupling
Caloric stimulation of ampullar receptors: a new method to produce mechanically-evoked responses in frog semicircular canals
A microthermistor positioned close to the exposed posterior semicircular canal in isolated labyrinth preparations of the frog was used to stimulate the sensory organ. Our results indicated that, depending on the position of the heater, the induced endolymphatic convection currents may result in either excitatory or inhibitory cupular deflections and thus in a modulation of ampullar receptor resting activity. Other possible thermal-dependent mechanisms, such as a direct action of the stimulus on vestibular sensors or endolymphatic volume changes, had, in the present experimental conditions, a minor role. Caloric stimulation could therefore represent a novel method to stimulate the semicircular canals 'in situ'
Combined analysis of the salivary microbiome and host defence peptides predicts dental disease
Understanding the triad of host response, microbiome and disease status is potentially informative for disease prediction, prevention, early intervention and treatment. Using longitudinal assessment of saliva and disease status, we demonstrated that partial least squares modelling of microbial, immunological and clinical measures, grouped children according to future dental disease status. Saliva was collected and dental health assessed in 33 children aged 4 years, and again 1-year later. The composition of the salivary microbiome was assessed and host defence peptides in saliva were quantified. Principal component analysis of the salivary microbiome indicated that children clustered by age and not disease status. Similarly, changes in salivary host defence peptides occurred with age and not in response to, or preceding dental caries. Partial least squares modelling of microbial, immunological and clinical baseline measures clustered children according to future dental disease status. These data demonstrate that isolated evaluation of the salivary microbiome or host response failed to predict dental disease. In contrast, combined assessment of both host response together with the microbiome revealed clusters of health and disease. This type of approach is potentially relevant to myriad diseases that are modified by host–microbiome interactions
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