148 research outputs found
Spin and the Coulomb Gap in the Half-Filled Lowest Landau Level
The Coulomb gap observed in tunneling between parallel two-dimensional
electron systems, each at half filling of the lowest Landau level, is found to
depend sensitively on the presence of an in-plane magnetic field. Especially at
low electron density, the width of the Coulomb gap at first increases sharply
with in-plane field, but then abruptly levels off. This behavior appears to
coincide with the known transition from partial to complete spin polarization
of the half-filled lowest Landau level. The tunneling gap therefore opens a new
window onto the spin configuration of two-dimensional electron systems at high
magnetic field.Comment: 6 pages, 4 postscript figures. Minor changes. To appear in Physical
Review
Searching for the Imprints of AGN Feedback on the Lyman Alpha Forest Around Luminous Red Galaxies
We explore the potential of using the low-redshift Lyman-
(Ly) forest surrounding luminous red galaxies (LRGs) as a tool to
constrain active galactic nuclei (AGN) feedback models. Our analysis is based
on snapshots from the Illustris and IllustrisTNG simulations at a redshift of
. These simulations offer an ideal platform for studying the influence
of AGN feedback on the gas surrounding galaxies, as they share the same initial
conditions and underlying code but incorporate different feedback
prescriptions. Both simulations show significant impacts of feedback on the
temperature and density of the gas around massive halos. Following our previous
work, we adjusted the UV background in both simulations to align with the
observed number density of Ly lines () in the intergalactic
medium and study the Ly forest around massive halos hosting LRGs, at
impact parameters () ranging from 0.1 to 100 pMpc. Our findings
reveal that , as a function of , is approximately 1.5 to
2 times higher in IllustrisTNG compared to Illustris up to of pMpc. To further assess whether existing data can effectively discern these
differences, we search for archival data containing spectra of background
quasars probing foreground LRGs. Through a feasibility analysis based on this
data, we demonstrate that measurements can
distinguish between feedback models of IllustrisTNG and Illustris with a
precision exceeding 12. This underscores the potential of measurements around LRGs as a valuable benchmark observation for
discriminating between different feedback models.Comment: 21 pages (including 4 page appendix), Submitted to MNRA
Evaluation of antioxidant potentials and total phenolic contents of selected Indian herbs powder extracts
Abstract The aim of the study was to compare 19 commonly used antidiabetic plants for their antioxidant potential by seven assays and identify the plants that are good sources of natural antioxidants. The antioxidant potential was evaluated by estimating reducing power (using potassium ferricyanide), lipid peroxidation inhibitory activity (thiobarbituric acid assay) and scavenging activities of DPPH • , ABTS • , NO • and H 2 O 2 • radicals; whereas total phenolic contents were also estimated. T. chebula extract demonstrated high phenolic content with significant antioxidant activity. Total phenolic content were positively correlated with reducing power and ABTS scavenging activity. However, three plant extracts (C. mukul, P. crispum and W. somnifera) having less phenolic contents exhibited excellent antioxidant potential and some plants (T. arjuna, S. reticulata and G. glabra) with high phenolics where devoid of comparable antioxidant property. Results indicate that the plants extracts offer promising sources of natural antioxidants and in addition to phenolics, there could be other non phenolic antioxidants which contribute to antioxidant potential
Tunneling at v_T = 1 in Quantum Hall Bilayers
Interlayer tunneling measurements in the strongly correlated bilayer quantized Hall phase at ν_T = 1 are reported. The maximum, or critical, current for tunneling at ν_T = 1 is shown to be a well-defined global property of the coherent phase, insensitive to extrinsic circuit effects and the precise configuration used to measure it, but also exhibiting a surprising scaling behavior with temperature. Comparisons between the experimentally observed tunneling characteristics and a recent theory are favorable at high temperatures, but not at low temperatures where the tunneling closely resembles the dc Josephson effect. The zero-bias tunneling resistance becomes extremely small at low temperatures, vastly less than that observed at zero magnetic field, but nonetheless remains finite. The temperature dependence of this tunneling resistance is similar to that of the ordinary in-plane resistivity of the quantum Hall phase
On the Puzzle of Odd-Frequency Superconductivity
Since the first theoretical proposal by Berezinskii, an odd-frequency
superconductivity has encountered the fundamental problems on its thermodynamic
stability and rigidity of a homogenous state accompanied by unphysical Meissner
effect. Recently, Solenov {\it et al}. [Phys. Rev. B {\bf 79} (2009) 132502.]
have asserted that the path-integral formulation gets rid of the difficulties
leading to a stable homogenous phase with an ordinary Meissner effect. Here, we
show that it is crucial to choose the appropriate saddle-point solution that
minimizes the effective free energy, which was assumed {\it implicitly} in the
work by Solenov and co-workers. We exhibit the path-integral framework for the
odd-frequency superconductivity with general type of pairings, including an
argument on the retarded functions via the analytic continuation to the real
axis.Comment: 6 pages, in JPSJ forma
Design and Bolometer Characterization of the SPT-3G First-year Focal Plane
During the austral summer of 2016-17, the third-generation camera, SPT-3G,
was installed on the South Pole Telescope, increasing the detector count in the
focal plane by an order of magnitude relative to the previous generation.
Designed to map the polarization of the cosmic microwave background, SPT-3G
contains ten 6-in-hexagonal modules of detectors, each with 269 trichroic and
dual-polarization pixels, read out using 68x frequency-domain multiplexing.
Here we discuss design, assembly, and layout of the modules, as well as early
performance characterization of the first-year array, including yield and
detector properties.Comment: Conference proceeding for Low Temperature Detectors 2017. Accepted
for publication: 27 August 201
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