3,886 research outputs found

    Intramuscular injury between muscularis propria circular and longitudinal layers : a novel subtype of Sydney III deep mural injury?

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    Assessment of the defect after endoscopic resection of colorectal neoplastic lesions is standard in routine endoscopy and instrumental in identifying deep muscular injury (DMI) up to frank perforation in need of immediate endoscopic closure. DMI involving the muscularis propria, classified as a Sydney III lesion, usually implies complete muscularis propria transection. By contrast, intramuscular resection with potential implications in terms of complication risks, such as rate of post-electrocautery syndrome, has not been reported before [1] (Fig. 1)

    Comment about constraints on nanometer-range modifications to gravity from low-energy neutron experiments

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    A topic of present interest is the application of experimentally observed quantum mechanical levels of ultra-cold neutrons in the earth's gravitational field for searching short-range modifications to gravity. A constraint on new forces in the nanometer-range published by Nesvizhevsky and Protasov follows from inadequate modelling of the interaction potential of a neutron with a mirror wall. Limits by many orders of magnitude better were already derived long ago from the consistency of experiments on the neutron-electron interaction.Comment: three page

    Selected Letters from the Parker Family Papers: The Correspondence of Margaret Parker

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    This thesis is a collection of the correspondence of Margaret Parker (nee Ellegood), an eighteenth century Norfolk merchant\u27s wife, The fifty-seven items, which cover the years from 1760 through 1785 and deal mainly with domestic matters, were transcribed from the microfilms of the Parker Family Papers, 1760-1795, Walter Minchinton, general editor {Micro Methods Ltd,,1964). The transcriptions have been arranged chronologically, annotated, and supplemented with background material concerning the Ellegood and Parker families, the history of Norfolk Borough and Princess Anne County, and the place, of women in eighteenth century society

    Observability of an induced electric dipole moment of the neutron from nonlinear QED

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    It has been shown recently that a neutron placed in an external quasistatic electric field develops an induced electric dipole moment pIND\mathbf{p}_{\mathrm{IND}} due to quantum fluctuations in the QED vacuum. A feasible experiment which could detect such an effect is proposed and described here. It is shown that the peculiar angular dependence of pIND\mathbf{p}_{\mathrm{IND}} on the orientation of the neutron spin leads to a characteristic asymmetry in polarized neutron scattering by heavy nuclei. This asymmetry can be of the order of 10310^{-3} for neutrons with epithermal energies. For thermalized neutrons from a hot moderator one still expects experimentally accessible values of the order of 10410^{-4}. The contribution of the induced effect to the neutron scattering length is expected to be only one order of magnitude smaller than that due to the neutron polarizability from its quark substructure. The experimental observation of this scattering asymmetry would be the first ever signal of nonlinearity in electrodynamics due to quantum fluctuations in the QED vacuum

    Spin-glass phase transition and behavior of nonlinear susceptibility in the Sherrington-Kirkpatrick model with random fields

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    The behavior of the nonlinear susceptibility χ3\chi_3 and its relation to the spin-glass transition temperature TfT_f, in the presence of random fields, are investigated. To accomplish this task, the Sherrington-Kirkpatrick model is studied through the replica formalism, within a one-step replica-symmetry-breaking procedure. In addition, the dependence of the Almeida-Thouless eigenvalue λAT\lambda_{\rm AT} (replicon) on the random fields is analyzed. Particularly, in absence of random fields, the temperature TfT_f can be traced by a divergence in the spin-glass susceptibility χSG\chi_{\rm SG}, which presents a term inversely proportional to the replicon λAT\lambda_{\rm AT}. As a result of a relation between χSG\chi_{\rm SG} and χ3\chi_3, the latter also presents a divergence at TfT_f, which comes as a direct consequence of λAT=0\lambda_{\rm AT}=0 at TfT_f. However, our results show that, in the presence of random fields, χ3\chi_3 presents a rounded maximum at a temperature TT^{*}, which does not coincide with the spin-glass transition temperature TfT_f (i.e., T>TfT^* > T_f for a given applied random field). Thus, the maximum value of χ3\chi_3 at TT^* reflects the effects of the random fields in the paramagnetic phase, instead of the non-trivial ergodicity breaking associated with the spin-glass phase transition. It is also shown that χ3\chi_3 still maintains a dependence on the replicon λAT\lambda_{\rm AT}, although in a more complicated way, as compared with the case without random fields. These results are discussed in view of recent observations in the LiHox_xY1x_{1-x}F4_4 compound.Comment: accepted for publication in PR

    Role of the transverse field in inverse freezing in the fermionic Ising spin-glass model

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    We investigate the inverse freezing in the fermionic Ising spin-glass (FISG) model in a transverse field Γ\Gamma. The grand canonical potential is calculated in the static approximation, replica symmetry and one-step replica symmetry breaking Parisi scheme. It is argued that the average occupation per site nn is strongly affected by Γ\Gamma. As consequence, the boundary phase is modified and, therefore, the reentrance associated with the inverse freezing is modified too.Comment: 6 pages, 3 figures, accepted for publication in PR

    BootBandit: A macOS bootloader attack

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    Historically, the boot phase on personal computers left systems in a relatively vulnerable state. Because traditional antivirus software runs within the operating system, the boot environment is difficult to protect from malware. Examples of attacks against bootloaders include so‐called “evil maid” attacks, in which an intruder physically obtains a boot disk to install malicious software for obtaining the password used to encrypt a disk. The password then must be stored and retrieved again through physical access. In this paper, we discuss an attack that borrows concepts from the evil maid. We assume exploitation can be used to infect a bootloader on a system running macOS remotely to install code to steal the user\u27s password. We explore the ability to create a communication channel between the bootloader and the operating system to remotely steal the password for a disk protected by FileVault 2. On a macOS system, this attack has additional implications due to “password forwarding” technology, in which a user\u27s account password also serves as the FileVault password, enabling an additional attack surface through privilege escalation
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