2,161 research outputs found
X-Ray-Diffraction Study of Charge-Density-Waves and Oxygen-Ordering in YBa2Cu3O6+x Superconductor
We report a temperature-dependent increase below 300 K of diffuse
superlattice peaks corresponding to q_0 =(~2/5,0,0) in an under-doped
YBa_2Cu_3O_6+x superconductor (x~0.63). These peaks reveal strong c-axis
correlations involving the CuO_2 bilayers, show a non-uniform increase below
\~220 K with a plateau for ~100-160 K, and appear to saturate in the
superconducting phase. We interpret this unconventional T-dependence of the
``oxygen-ordering'' peaks as a manifestation of a charge density wave in the
CuO_2 planes coupled to the oxygen-vacancy ordering.Comment: 4 pages, 4 figure
Analytical time-like geodesics
Time-like orbits in Schwarzschild space-time are presented and classified in
a very transparent and straightforward way into four types. The analytical
solutions to orbit, time, and proper time equations are given for all orbit
types in the form r=r(\lambda), t=t(\chi), and \tau=\tau(\chi), where \lambda\
is the true anomaly and \chi\ is a parameter along the orbit. A very simple
relation between \lambda\ and \chi\ is also shown. These solutions are very
useful for modeling temporal evolution of transient phenomena near black holes
since they are expressed with Jacobi elliptic functions and elliptic integrals,
which can be calculated very efficiently and accurately.Comment: 15 pages, 10 figures, accepted by General Relativity and Gravitatio
Beyond the Syndrome: Extensive Congenital Abnormalities in an Infant With Trisomy 21
Herein we discuss the clinical course and subsequent autopsy of a female infant with trisomy 21 with balanced Rastelli Type ?C? complete atrioventricular septal defect (AVSD), tetralogy of Fallot and right aortic arch with mirror image branching pattern who underwent a palliative right modified Blalock-Taussig-Thomas shunt (mBTTS) for hypoxemia from progressive right ventricular outflow tract obstruction. The baby was found to have multiple concomitant pathologic findings not typically seen with this constellation of cardiac anatomy. Autopsy revealed significant abdominal adhesions with near-complete stenosis of the transverse colon. In addition, the infant was found to have significantly elongated villi within the small and large bowel and a relatively large collagenous polyp in the small bowel. The decedent also had an abnormal tracheal bronchus, characterized by an additional superior right-sided bronchus, which is an extremely rare abnormality. Her clinical course was complicated by severe pulmonary hypertensive arteriolar changes out of proportion to what would be typical for her age, trisomy 21 status, and degree of left to right intracardiac shunting. Furthermore, she had refractory anasarca and recurrent chylous pleural effusions without gross lymphatic abnormalities that may have been secondary to systemic capillary leak syndrome (SCLS) versus severe pulmonary hypertension. Due to the aforementioned findings, the family elected for comfort care and the baby expired shortly after extubation. Overall, the infant had multiple, rare coexisting congenital abnormalities that likely represents an extreme phenotype of trisomy 21 that has not been described in the literature to date
The effects of dietary supplementation with inulin and inulin-propionate ester on hepatic steatosis in adults with non-alcoholic fatty liver disease
The short chain fatty acid (SCFA) propionate, produced through fermentation of dietary fibre by the gut microbiota, has been shown to alter hepatic metabolic processes that reduce lipid storage. We aimed to investigate the impact of raising colonic propionate production on hepatic steatosis in adults with non-alcoholic fatty liver disease (NAFLD). Eighteen adults were randomised to receive 20g/day of an inulin-propionate ester (IPE), designed to deliver propionate to the colon, or an inulin-control for 42-days in a parallel design. The change in intrahepatocellular lipid (IHCL) following the supplementation period was not different between groups (P=0.082), however IHCL significantly increased within the inulin-control group (20.9±2.9 to 26.8±3.9%; P=0.012; n=9), which was not observed within the IPE group (22.6±6.9 to 23.5±6.8%; P=0.635; n=9). The predominant SCFA from colonic fermentation of inulin is acetate, which in a background of NAFLD and a hepatic metabolic profile that promotes fat accretion, may provide surplus lipogenic substrate to the liver. The increased colonic delivery of propionate from IPE appears to attenuate this acetate- mediated increase in IHC
Possible charge inhomogeneities in the CuO2 planes of YBa2Cu3O6+x (x=0.25, 0.45, 0.65, 0.94) from pulsed neutron diffraction
The atomic pair distribution functions (PDF) of four powder samples of
YBa2Cu3O6+x (x=0.25, 0.45, 0.65, 0.94) at 15 K have been measured by means of
pulsed neutron diffraction. The PDF is modelled using a full-profile fitting
approach to yield structural parameters. In contrast to earlier XAFS work we
find no evidence of a split apical oxygen site. However, a slightly improved
fit over the average crystallographic model results when the planar Cu(2) site
is split along the z-direction. This is interpreted in terms of charge
inhomogeneities in the CuO2 planes.Comment: 8 pages, 3 figure
Thermal photons as a measure for the rapidity dependence of the temperature
The rapidity distribution of thermal photons produced in Pb+Pb collisions at
CERN-SPS energies is calculated within scaling and three-fluid hydrodynamics.
It is shown that these scenarios lead to very different rapidity spectra. A
measurement of the rapidity dependence of photon radiation can give cleaner
insight into the reaction dynamics than pion spectra, especially into the
rapidity dependence of the temperature.Comment: 3 Figure
Resistance Status of the Malaria Vector Mosquitoes, Anopheles stephensi and Anopheles subpictus Towards Adulticides and Larvicides in Arid and Semi-Arid Areas of India
Susceptibility studies of malaria vectors Anopheles stephensi Liston (Diptera: Culicidae) and An. subpictus Grassi collected during 2004–2007 from various locations of Arid and Semi-Arid Zone of India were conducted by adulticide bioassay of DDT, malathion, deltamethrin and larvicide bioassay of fenthion, temephos, chlorpyriphos and malathion using diagnostic doses. Both species from all locations exhibited variable resistance to DDT and malathion from majority of location. Adults of both the species were susceptible to Deltamethrin. Larvae of both the Anopheline species showed some evidence of resistance to chlorpyriphos followed by fenthion whereas susceptible to temephos and malathion
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