2,366 research outputs found
Disorder-enhanced phase coherence in trapped bosons on optical lattices
The consequences of disorder on interacting bosons trapped in optical
lattices are investigated by quantum Monte Carlo simulations. At small to
moderate strengths of potential disorder a unique effect is observed: if there
is a Mott plateau at the center of the trap in the clean limit, phase coherence
{\it increases} as a result of disorder. The localization effects due to
correlation and disorder compete against each other, resulting in a partial
delocalization of the particles in the Mott region, which in turn leads to
increased phase coherence. In the absence of a Mott plateau, this effect is
absent. A detailed analysis of the uniform system without a trap shows that the
disordered states participate in a Bose glass phase.Comment: 4 pages, 4 figure
Age dependence of serum beta-N-acetylhexosaminidase (NAG) activity
Serum Nacetyl-beta-Dglucosaminidase (NAG; EC 3.2.1.30) is a hexosaminidase and may be a predictor of vascular injury, e.g., in infant respiratory distress syndrome, pneumonia, bronchopulmonary dysplasia and necrotizing enterocolitis. To estimate the new diagnostic prospects we have modified our urinary NAG assay. In this sensitive colorimetric microassay, VRAGlcNAc was used as a substrate. In the present study the age dependence of serum NAG activity was investigated in newborn babies, infants (124 months), children (218 years) and adults (1980 years). Serum NAG activity was found to be agedependent; it is higher in early childhood (1159 U/l) but decreases to a constant value at the age of 12 years. After the age of 2 years it is similar to adults NAG (1030 U/l). In pediatrics agematched reference ranges must be taken into consideration
Coherent dynamics of Bose-Einstein condensates in high-finesse optical cavities
We study the mutual interaction of a Bose-Einstein condensed gas with a
single mode of a high-finesse optical cavity. We show how the cavity
transmission reflects condensate properties and calculate the self-consistent
intra-cavity light field and condensate evolution. Solving the coupled
condensate-cavity equations we find that while falling through the cavity, the
condensate is adiabatically transfered into the ground state of the periodic
optical potential. This allows time dependent non-destructive measurements on
Bose-Einstein condensates with intriguing prospects for subsequent controlled
manipulation.Comment: 5 pages, 5 figures; revised version: added reference
Toxic effects of orally ingested oil from the Deepwater Horizon spill on laughing gulls
The explosion of the Deepwater Horizon oil rig released millions of gallons of oil into the environment, subsequently exposing wildlife, including numerous bird species. To determine the effects of MC252 oil to species relevant to the Gulf of Mexico, studies were done examining multiple exposure scenarios and doses. In this study, laughing gulls (Leucophaeus atricilla, LAGU) were offered fish injected with MC252 oil at target doses of 5 or 10 mL/kg bw per day. Dosing continued for 27 days. Of the adult, mixed-sex LAGUs used in the present study, 10 of 20 oil exposed LAGUs survived to the end of the study; a total of 10 of the oil exposed LAGUs died or were euthanized within 20 days of initiation of the study. Endpoints associated with oxidative stress, hepatic total glutathione (tGSH), oxidized glutathione (GSSG) and reduced glutathione (rGSH) significantly increased as mean dose of oil increased, while the rGSH:GSSG ratio showed a non-significant negative trend with oil dose. A significant increase in 3-methyl histidine was found in oil exposed birds when compared to controls indicative of muscle wastage and may have been associated with the gross observation of diminished structural integrity in cardiac tissue. Consistent with previous oil dosing studies in birds, significant changes in liver, spleen, and kidney weight when normalized to body weight were observed. These studies indicate that mortality in response to oil dosing is relatively common and the mortality exhibited by the gulls is consistent with previous studies examining oil toxicity. Whether survival effects in the gull study were associated with weight loss, physiologic effects of oil toxicity, or a behavioral response that led the birds to reject the dosed fish is unknown
The interactive on-site inspection system: An information management system to support arms control inspections
The increasing use of on-site inspection (OSI) to meet the nation`s obligations with recently signed treaties requires the nation to manage a variety of inspection requirements. This document describes a prototype automated system to assist in the preparation and management of these inspections
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The interactive on-site inspection system: An information management system to support arms control inspections
The increasing use of on-site inspection (OSI) to meet the nation`s obligations with recently signed treaties requires the nation to manage a variety of inspection requirements. This document describes a prototype automated system to assist in the preparation and management of these inspections
Experimental and modeled thermoregulatory costs of repeated sublethal oil exposure in the Double-crested Cormorant, \u3ci\u3ePhalacrocorax auritus\u3c/i\u3e
To fully understand the impact of oil exposure, it is important to understand sublethal effects like how increased thermoregulatory costs may affect survival and reproduction. However, it is difficult and time-consuming to measure these effects in wild animals. We present a novel use of a bioenergetics model, Niche Mapper™, to estimate thermoregulatory impacts of oiling, using data from captive Double-crested Cormorants (Phalacrocorax auritus) experimentally exposed to oil. Oiled cormorants had significant increases in surface body temperatures following exposure. Niche Mapper accurately predicted surface temperatures and metabolic rates for unoiled and oiled cormorants and predicted 13–18% increased daily energetic demands due to increased thermoregulatory costs of oiling, consistent with increased food consumption observed in experimentally oiled cormorants. We show that Niche Mapper can provide valuable insight into sublethal oiling effects by quantifying the extent to which thermoregulatory costs divert energy resources away from important life processes like maintenance, reproduction and migration
Feasibility of detecting single atoms using photonic bandgap cavities
We propose an atom-cavity chip that combines laser cooling and trapping of
neutral atoms with magnetic microtraps and waveguides to deliver a cold atom to
the mode of a fiber taper coupled photonic bandgap (PBG) cavity. The
feasibility of this device for detecting single atoms is analyzed using both a
semi-classical treatment and an unconditional master equation approach.
Single-atom detection seems achievable in an initial experiment involving the
non-deterministic delivery of weakly trapped atoms into the mode of the PBG
cavity.Comment: 11 pages, 5 figure
Subdecoherent Information Encoding in a Quantum-Dot Array
A potential implementation of quantum-information schemes in semiconductor
nanostructures is studied. To this end, the formal theory of quantum encoding
for avoiding errors is recalled and the existence of noiseless states for model
systems is discussed. Based on this theoretical framework, we analyze the
possibility of designing noiseless quantum codes in realistic semiconductor
structures. In the specific implementation considered, information is encoded
in the lowest energy sector of charge excitations of a linear array of quantum
dots. The decoherence channel considered is electron-phonon coupling We show
that besides the well-known phonon bottleneck, reducing single-qubit
decoherence, suitable many-qubit initial preparation as well as register design
may enhance the decoherence time by several orders of magnitude. This behaviour
stems from the effective one-dimensional character of the phononic environment
in the relevant region of physical parameters.Comment: 12 pages LaTeX, 5 postscript figures. Final version accepted by PR
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