2,706 research outputs found
Weak Lensing of Galaxy Clusters in MOND
We study weak gravitational lensing of galaxy clusters in terms of the MOND
(MOdified Newtonian Dynamics) theory. We calculate shears and convergences of
background galaxies for three clusters (A1689, CL0024+1654, CL1358+6245) and
the mean profile of 42 SDSS (Sloan Digital Sky Survey) clusters and compare
them with observational data. The mass profile is modeled as a sum of X-ray
gas, galaxies and dark halo. For the shear as a function of the angular radius,
MOND predicts a shallower slope than the data irrespective of the critical
acceleration parameter . The dark halo is necessary to explain the data
for any and for three interpolation functions. If the dark halo is
composed of massive neutrinos, its mass should be heavier than 2 eV. However
the constraint still depends on the dark halo model and there are systematic
uncertainties, and hence the more careful study is necessary to put a stringent
constraint.Comment: 12 pages, 7 figures, references added, minor changes, accepted for
publication in Ap
Orbital Optimization in the Density Matrix Renormalization Group, with applications to polyenes and \beta-carotene
In previous work we have shown that the Density Matrix Renormalization Group
(DMRG) enables near-exact calculations in active spaces much larger than are
possible with traditional Complete Active Space algorithms. Here, we implement
orbital optimisation with the Density Matrix Renormalization Group to further
allow the self-consistent improvement of the active orbitals, as is done in the
Complete Active Space Self-Consistent Field (CASSCF) method. We use our
resulting DMRGCASSCF method to study the low-lying excited states of the
all-trans polyenes up to C24H26 as well as \beta-carotene, correlating with
near-exact accuracy the optimised complete \pi-valence space with up to 24
active electrons and orbitals, and analyse our results in the light of the
recent discovery from Resonance Raman experiments of new optically dark states
in the spectrum.Comment: 16 pages, 8 figure
Building the Next Generation Technology Transfer Information System
The Defense Technology Transfer Information System (DTTIS) is a scalable data system built to grow and adapt to changing conditions. It collects information from each technology transfer offices, patent attorneys, innovators, and more. It automates workflows to standardize and streamline technology transfer business rules. This resulting in improved efficiency, standardized processes and reducing errors. DTTIS is a search and reporting engine built on patented NASA's Technology Transfer System (NTTS) core software platform
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EUS-guided portal pressure gradient measurement with a simple novel device: a human pilot study.
Background and aimsPortal hypertension is a serious adverse event of liver cirrhosis. Recently, we developed a simple novel technique for EUS-guided portal pressure gradient (PPG) measurement (PPGM). Our animal studies showed excellent correlation between EUS-PPGM and interventional radiology-acquired PPGM. In this video we demonstrate the results of the first human pilot study of EUS-PPGM in patients with liver disease.MethodsEUS-PPGM was performed by experienced endosonographers using a linear echoendoscope, a 25-gauge FNA needle, and a novel compact manometer. The portal vein and hepatic vein (or inferior vena cava) were targeted by use of a transgastric or transduodenal approach. Feasibility was defined as successful PPGM in each patient. Safety was based on adverse events captured in a postprocedural interview.ResultsTwenty-eight patients underwent EUS-PPGM with 100% technical success and no adverse events. PPG ranged from 1.5 to 19 mm Hg and had excellent correlation with clinical parameters of portal hypertension, including the presence of varices (P = .0002), PH gastropathy (P = .007), and thrombocytopenia (P = .036).ConclusionThis novel technique of EUS-PPGM using a 25-gauge needle and compact manometer is feasible and appears safe. Given the availability of EUS and the simplicity of the manometry setup, EUS-guided PPG may represent a promising breakthrough for procuring indispensable information in the management of patients with liver disease
ALMA Observations of the IRDC Clump G34.43+00.24 MM3: DNC/HNC Ratio
We have observed the clump G34.43+00.24 MM3 associated with an infrared dark
cloud in DNC =3--2, HNC =3--2, and NH =3--2 with the
Atacama Large Millimeter/submillimeter Array (ALMA). The NH emission is
found to be relatively weak near the hot core and the outflows, and its
distribution is clearly anti-correlated with the CS emission. This result
indicates that a young outflow is interacting with cold ambient gas. The
HNC emission is compact and mostly emanates from the hot core, whereas
the DNC emission is extended around the hot core. Thus, the DNC and HNC
emission traces warm regions near the protostar differently. The DNC emission
is stronger than the HNC emission toward most parts of this clump. The
DNC/HNC abundance ratio averaged within a area around the phase center is higher than 0.06. This ratio
is much higher than the value obtained by the previous single-dish observations
of DNC and HNC =1--0 (0.003). It seems likely that the DNC and
HNC emission observed with the single-dish telescope traces lower density
envelopes, while that observed with ALMA traces higher density and highly
deuterated regions. We have compared the observational results with
chemical-model results in order to investigate the behavior of DNC and HNC in
the dense cores. Taking these results into account, we suggest that the low
DNC/HNC ratio in the high-mass sources obtained by the single-dish observations
are at least partly due to the low filling factor of the high density regions.Comment: accepted to Ap
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