286 research outputs found
Settlement in Sands Due to Cyclic Loading
Stress controlled undrained cyclic triaxial tests have been conducted on undisturbed sandy and silty soil samples obtained by special sampler in order to minimize the effect of disturbance. The influence of fines content on liquefaction - induced volumetric strains have been studied. The results indicate that cyclic mobility of sands is affected by non – plastic fines content. As fines content increase, cyclic shear strength decreases. Volumetric strain is influenced by fines content as well as shear strain and cyclic stress. At large shear strains amplitudes, an increase in percentage of fines causes more volumetric strains. Volumetric strains of silt samples are affected by cyclic shear stress more than sands
Cosmic axion thermalization
Axions differ from the other cold dark matter candidates in that they form a
degenerate Bose gas. It is shown that their huge quantum degeneracy and large
correlation length cause cold dark matter axions to thermalize through
gravitational self-interactions when the photon temperature reaches
approximately 500 eV. When they thermalize, the axions form a Bose-Einstein
condensate. Their thermalization occurs in a regime, herein called the
`condensed regime', where the Boltzmann equation is not valid because the
energy dispersion of the particles is smaller than their interaction rate. We
derive analytical expressions for the thermalization rate of particles in the
condensed regime, and check the validity of these expressions by numerical
simulation of a toy model. We revisit axion cosmology in light of axion
Bose-Einstein condensation. It is shown that axions are indistinguishable from
ordinary cold dark matter on all scales of observational interest, except when
they thermalize or rethermalize. The rethermalization of axions that are about
to fall in a galactic potential well causes them to acquire net overall
rotation as they go to the lowest energy state consistent with the total
angular momentum they acquired by tidal torquing. This phenomenon explains the
occurrence of caustic rings of dark matter in galactic halos. We find that
photons may reach thermal contact with axions and investigate the implications
of this possibility for the measurements of cosmological parameters.Comment: 38 pages, 1 figur
Axions and saxions from the primordial supersymmetric plasma and extra radiation signatures
We calculate the rate for thermal production of axions and saxions via
scattering of quarks, gluons, squarks, and gluinos in the primordial
supersymmetric plasma. Systematic field theoretical methods such as hard
thermal loop resummation are applied to obtain a finite result in a
gauge-invariant way that is consistent to leading order in the strong gauge
coupling. We calculate the thermally produced yield and the decoupling
temperature for both axions and saxions. For the generic case in which saxion
decays into axions are possible, the emitted axions can constitute extra
radiation already prior to big bang nucleosynthesis and well thereafter. We
update associated limits imposed by recent studies of the primordial helium-4
abundance and by precision cosmology of the cosmic microwave background and
large scale structure. We show that the trend towards extra radiation seen in
those studies can be explained by late decays of thermal saxions into axions
and that upcoming Planck results will probe supersymmetric axion models with
unprecedented sensitivity.Comment: 16 pages, 7 figures; v2: references added, minor clarifying
additions, matches published versio
Effects of the hippocampal deep brain stimulation on cortical epileptic discharges in penicillin - induced epilepsy model in rats
Aim: Experimental and clinical studies have revealed that hippocampal DBS can control epileptic activity, but the mechanism of action is obscure and optimal stimulation parameters are not clearly defined. The aim was to evaluate the effects of high frequency hippocampal stimulation on cortical epileptic activity in penicillin-induced epilepsy model. Material and Methods: Twenty-five Sprague-Dawley rats were implanted DBS electrodes. In group-1 (n=10) hippocampal DBS was off and in the group-2 (n=10) hippocampal DBS was on (185 Hz, 0.5V, 1V, 2V, and 5V for 60 sec) following penicillin G injection intracortically. In the control group hippocampal DBS was on following 8μl saline injection intracortically. EEG recordings were obtained before and 15 minutes following penicillin-G injection, and at 10th minutes following each stimulus for analysis in terms of frequency, amplitude, and power spectrum. Results: High frequency hippocampal DBS suppressed the acute penicillin-induced cortical epileptic activity independent from stimulus intensity. In the control group, hippocampal stimulation alone lead only to diffuse slowing of cerebral bioelectrical activity at 5V stimulation. Conclusion: Our results revealed that continuous high frequency stimulation of the hippocampus suppressed acute cortical epileptic activity effectively without causing secondary epileptic discharges. These results are important in terms of defining the optimal parameters of hippocampal DBS in patients with epilepsy
Human MLH1 deficiency predisposes to hematological malignancy and neurofibromatosis type 1
Heterozygous germ-line mutations in the DNA mismatch repair genes lead to hereditary nonpolyposis colorectal cancer. The disease susceptibility of individuals who constitutionally lack both wild-type alleles is unknown. We have identified three offspring in a hereditary nonpolyposis colorectal cancer family who developed hematological malignancy at a very early age, and at least two of them displayed signs of neurofibromatosis type 1 (NF1). DNA sequence analysis and allele-specific amplification in two siblings revealed a homozygous MLH1 mutation (C676T → Arg226Stop). Thus, a homozygous germ- line MLH1 mutation and consequent mismatch repair deficiency results in a mutator phenotype characterized by leukemia and/or lymphoma associated with neurofibromatosis type 1
Farnesoid X receptor agonist for the treatment of chronic hepatitis B: a safety study
The nuclear farnesoid X receptor (FXR) regulates bile acid homeostasis and is a drug target for metabolic liver diseases. FXR also plays an important role in hepatitis B virus (HBV) DNA transcription. In vitro and in mice, FXR agonist treatment leads to inhibition of viral replication and a decline in viral proteins, pregenomic RNA (pgRNA) and HBV DNA levels. We aimed to translate this to a clinical use by primarily evaluating the safety and secondary the anti-viral effect of Vonafexor, a FXR agonist, in chronic hepatitis B (CHB) patients. In total, 73 CHB patients were enrolled in a two-part Phase Ib double-blind, placebo-controlled trial. Patients were randomized to receive oral Vonafexor (100, 200 and 400 mg once daily, or 200 mg twice daily), placebo, or entecavir (Part A, n = 48) or to receive Vonafexor (300 mg once daily or 150 mg twice daily), or placebo, combined with pegylated-interferon-alpha 2a (Part B, n = 25) for 29 days. Patients were followed up for 35 days. Enrolled CHB patients were mostly HBeAg-negative. Vonafexor was overall well tolerated and safe. The most frequent adverse events were moderate gastrointestinal events. Pruritus was more frequent with twice-daily compared with once-daily regimens (56%-67% vs. 16%, respectively, p < 0.05). Vonafexor monotherapy of 400 mg once daily decreased HBsAg concentrations (-0.1 log(10) IU/mL, p < 0.05), and Vonafexor/pegylated-IFN-alpha 2a combination therapy decreased HBcrAg and pgRNA. In conclusion, Vonafexor was safe with a decline in HBV markers observed in CHB patients suggesting a potential anti-viral effect the therapeutic potential of which has to be evaluated in larger trials.Cellular mechanisms in basic and clinical gastroenterology and hepatolog
Coupled Boltzmann calculation of mixed axion/neutralino cold dark matter production in the early universe
We calculate the relic abundance of mixed axion/neutralino cold dark matter
which arises in R-parity conserving supersymmetric (SUSY) models wherein the
strong CP problem is solved by the Peccei-Quinn (PQ) mechanism with a
concommitant axion/saxion/axino supermultiplet. By numerically solving the
coupled Boltzmann equations, we include the combined effects of 1. thermal
axino production with cascade decays to a neutralino LSP, 2. thermal saxion
production and production via coherent oscillations along with cascade decays
and entropy injection, 3. thermal neutralino production and re-annihilation
after both axino and saxion decays, 4. gravitino production and decay and 5.
axion production both thermally and via oscillations. For SUSY models with too
high a standard neutralino thermal abundance, we find the combined effect of
SUSY PQ particles is not enough to lower the neutralino abundance down to its
measured value, while at the same time respecting bounds on late-decaying
neutral particles from BBN. However, models with a standard neutralino
underabundance can now be allowed with either neutralino or axion domination of
dark matter, and furthermore, these models can allow the PQ breaking scale f_a
to be pushed up into the 10^{14}-10^{15} GeV range, which is where it is
typically expected to be in string theory models.Comment: 26 pages with 12 .eps figure
Pathways between childhood trauma, intimate partner violence, and harsh parenting : findings from the UN multi-country study on men and violence in Asia and the Pacific
2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordPublishe
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