11,175 research outputs found

    A model of a pumped continuous atom laser

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    We present a model of a cw atom laser based on a system of coupled GP equations. The model incorporates continuous Raman outcoupling, pumping and three-body recombination. The outcoupled field has minimal atomic density fluctuations and is locally monochromatic.Comment: 10 pages, 8 eps figures, typos fixe

    On the Identification of Information Extracted from Windows Physical Memory

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    Forensic investigation of the physical memory of computer systems is gaining the attention of experts in the digital forensics community. Forensic investigators find it helpful to seize and capture data from the physical memory and perform post-incident analysis when identifying potential evidence. However, there have been few investigations which have identified the quantity and quality of information that can be recovered from only the computer system memory (RAM) while the application is still running. In this paper, we present the results of investigations carried out to identify relevant information that has been extracted from the physical memory of computer systems running Windows XP. We found fragments of partial evidence from allocated memory segments. This evidence was dispersed in the physical memory that had been allocated to the application. The identification of this information is useful to forensic investigators as this approach can uncover what a user is doing on the application which can be used as evidence

    Probing Hadronic Structure with The Decay ΔNl+l\Delta\rightarrow Nl^+l^-

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    We compute the branching ratio for ΔNe+e\Delta\rightarrow Ne^+e^- and ΔNμ+μ\Delta\rightarrow N\mu^+\mu^- in chiral perturbation theory and find that both decays should be observable at CEBAF. With sufficiently low thresholds on the e+ee^+e^- invariant mass a branching ratio of 105\sim 10^{-5} may be observed for ΔNe+e\Delta\rightarrow Ne^+e^-. For the ΔNμ+μ\Delta\rightarrow N\mu^+\mu^- decay mode we predict a branching ratio of 3×1073\times 10^{-7}. The dependence of the M1 and E2 amplitudes on the momentum transfer will provide a useful test of chiral perturbation theory which predicts 20%\sim 20\% variation over the allowed kinematic range.Comment: 6 pages, 3 figures, UCSD/PTH 93-06, QUSTH-93-02, Duke-TH-93-4

    AS-825-17 Resolution on Academic Standards for Masters Degrees

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    Defines that graduate courses, as primarily for graduate study, follow guidelines in coded memo

    Stability of continuously pumped atom lasers

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    A multimode model of a continuously pumped atom laser is shown to be unstable below a critical value of the scattering length. Above the critical scattering length, the atom laser reaches a steady state, the stability of which increases with pumping. Below this limit the laser does not reach a steady state. This instability results from the competition between gain and loss for the excited states of the lasing mode. It will determine a fundamental limit for the linewidth of an atom laser beam.Comment: 4 page

    Clouds, photolysis and regional tropospheric ozone budgets.

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    We use a three-dimensional chemical transport model to examine the shortwave radiative effects of clouds on the tropospheric ozone budget. In addition to looking at changes in global concentrations as previous studies have done, we examine changes in ozone chemical production and loss caused by clouds and how these vary in different parts of the troposphere. On a global scale, we find that clouds have a modest effect on ozone chemistry, but on a regional scale their role is much more significant, with the size of the response dependent on the region. The largest averaged changes in chemical budgets (±10–14%) are found in the marine troposphere, where cloud optical depths are high. We demonstrate that cloud effects are small on average in the middle troposphere because this is a transition region between reduction and enhancement in photolysis rates. We show that increases in boundary layer ozone due to clouds are driven by large-scale changes in downward ozone transport from higher in the troposphere rather than by decreases in in-situ ozone chemical loss rates. Increases in upper tropospheric ozone are caused by higher production rates due to backscattering of radiation and consequent increases in photolysis rates, mainly J(NO2). The global radiative effect of clouds on isoprene, through decreases of OH in the lower troposphere, is stronger than on ozone. Tropospheric isoprene lifetime increases by 7% when taking clouds into account. We compare the importance of clouds in contributing to uncertainties in the global ozone budget with the role of other radiatively-important factors. The budget is most sensitive to the overhead ozone column, while surface albedo and clouds have smaller effects. However, uncertainty in representing the spatial distribution of clouds may lead to a large sensitivity of the ozone budget components on regional scales
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