12,418 research outputs found

    Characterisation of the dynamical quantum state of a zero temperature Bose-Einstein condensate

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    We describe the quantum state of a Bose-Einstein condensate at zero temperature. By evaluating the Q-function we show that the ground state of Bose-Einstein condensate under the Hartree approximation is squeezed. We find that multimode Schroedinger cat states are generated as the condensate evolves in a ballistic expansion.Comment: 13 pages, 6 figure

    Constant of Motion for several one-dimensional systems and outlining the problem associated with getting their Hamiltonians

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    The constants of motion of the following systems are deduced: a relativistic particle with linear dissipation, a no-relativistic particle with a time explicitly depending force, a no-relativistic particle with a constant force and time depending mass, and a relativistic particle under a conservative force with position depending mass. The problem of getting the Hamiltonian for these systems is determined by getting the velocity as an explicit function of position and generalized linear momentum, and this problem can be solved a first approximation for the first above system.Comment: 15 pages, Te

    Non-Singular Charged Black Hole Solution for Non-Linear Source

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    A non-singular exact black hole solution in General Relativity is presented. The source is a non-linear electromagnetic field, which reduces to the Maxwell theory for weak field. The solution corresponds to a charged black hole with |q| \leq 2s_c m \approx 0.6 m, having metric, curvature invariants, and electric field bounded everywhere.Comment: 3 pages, RevTe

    Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics

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    The first regular exact black hole solution in General Relativity is presented. The source is a nonlinear electrodynamic field satisfying the weak energy condition, which in the limit of weak field becomes the Maxwell field. The solution corresponds to a charged black hole with |q| \leq 2 s_c m \approx 0.6 m, having the metric, the curvature invariants, and the electric field regular everywhere.Comment: 5 pages, RevTex, 6 figure

    Disparities in access to musculoskeletal care: Narrowing the gap: AOA critical issues symposium

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    The current health-care system in the United States has numerous barriers to quality, accessible, and affordable musculoskeletal care for multiple subgroups of our population. These hurdles include complex cultural, educational, and socioeconomic factors. Tertiary referral centers provide a disproportionately large amount of the care for the uninsured and underinsured members of our society. These gaps in access to care for certain subgroups lead to inappropriate emergency room usage, lengthy hospitalizations, increased administrative load, lost productivity, and avoidable complications and/or deaths, which all represent a needless burden on our health-care system. Through advocacy, policy changes, workforce diversification, and practice changes, orthopaedic surgeons have a responsibility to seek solutions to improve access to quality and affordable musculoskeletal care for the communities that they serve

    Reproductive efficiency and viability in two \u3ci\u3eBos indicus \u3c/i\u3eand two \u3ci\u3eBos taurus \u3c/i\u3e breeds in the tropics of India and Colombia

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    Records from two herds in India and two in Columbia representing respectively two breeds of Bos indicus (Hariana and Deshi) and two Bos taurus breeds—Blanco Orejinegro (BON) and Costeño Con Cuernos (CCC) were evaluated for breeding efficiency and viability. Average age at first calving was 52.1, 46.3, 39.5 and 40.7 months for Hariana, Deshi, CCC and BON. Season of birth did not influence age at calving. Ranking for calving interval was similar, average 479, 418, 396 and 382 days with season effects significant (P\u3c.05) for only Deshi. BON and CCC had fewer days open but much shorter lactation periods, average 73 and 157, thus days carried calf in lactation were similar for all breeds. Percent of time dry per calving interval was high for all breeds, 44.2, 36.7, 64.1 and 81.0 for Hariana, Deshi, BON and CCC. Average annual mortality of females by 12 months of age was 23.6% for Hariana, 17.0% Deshi and 27.0% BON. In the same herds 46.4%, 51.1% and 49.0% of females born alive lived to first calving and annual losses among cows were 18.0%, 17.0%, and 21.0%; therefore, affording little opportunity for selection among females. Temperament, as determined by response to the milking process with and without the calf present, showed all the breeds were similar in this respect. Environmental effects were most important for all traits but genetic differences were indicated for age at first calving and milk yield. On a theoretical basis little gain could be expected in net dairy merit from crosses between the Columbian and Indian breeds

    Construction, gene delivery, and expression of DNA tethered nanoparticles

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    PURPOSE: Layered nanoparticles have the potential to deliver any number of substances to cells both in vitro and in vivo. The purpose of this study was to develop and test a relatively simple alternative to custom synthesized nanoparticles for use in multiple biological systems, with special focus on the eye. METHODS: The biotin-labeled transcriptionally active PCR products (TAP) were conjugated to gold, semiconductor nanocrystals, and magnetic nanoparticles (MNP) coated with streptavidin. The process of nanoparticle construction was monitored with gel electrophoresis. Fluorescence microscopy followed by image analysis was used to examine gene expression levels from DNA alone and tethered MNP in human hepatoma derived Huh-7 cells. Adult retinal endothelial cells from both dog (ADREC) and human (HREC) sources were transfected with nanoparticles and reporter gene expression evaluated with confocal and fluorescent microscopy. Transmission electron microscopy was used to quantify the concentration of nanoparticles in a stock solution. Nanoparticles were evaluated for transfection efficiency, determined by fluorescence microscopy cell counts. Cells treated with MNP were evaluated for increased reactive oxygen species (ROS) and necrosis with flow cytometry. RESULTS: Both 5' and 3' biotin-labeled TAP bound equally to MNP and there were no differences in functionality between the two tethering orientations. Free DNA was easily removed by the use of magnetic columns. These particles were also able to deliver genes to a human hepatoma cell line, Huh-7, but transfection efficiency was greater than TAP. The semiconductor nanocrystals and MNP had the highest transfection efficiencies. The MNP did not induce ROS formation or necrosis after 48 h of incubation. CONCLUSIONS: Once transfected, the MNP had reporter gene expression levels equivalent to TAP. The nanoparticles, however, had better transfection efficiencies than TAP. The magnetic nanoparticles were the most easily purified of all the nanoparticles tested. This strategy for bioconjugating TAP to nanoparticles is valuable because nanoparticle composition can be changed and the system optimized quickly. Since endothelial cells take up MNP, this strategy could be used to target neovascularization as occurs in proliferative retinopathies. Multiple cell types were used to test this technology and in each the nanoparticles were capable of transfection. In adult endothelial cells the MNP appeared innocuous, even at the highest doses tested with respect to ROS and necrosis. This technology has the potential to be used as more than just a vector for gene transfer, because each layer has the potential to perform its own unique function and then degrade to expose the next functional layer
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