2,438 research outputs found

    Skin Story: with critical introduction: “Scars left by the commonplace for women”.

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    A creative thesis with a story about themes of domestic violence focused particularly on an aspect of rape culture that does not directly involve rape: blamed femaleness. The critical introduction seeks to make this tie explicit to the text of the story

    Two-loop corrections to the decay rate of parapositronium

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    Order α2\alpha^2 corrections to the decay rate of parapositronium are calculated. A QED scattering calculation of the amplitude for electron-positron annihilation into two photons at threshold is combined with the technique of effective field theory to determine an NRQED Hamiltonian, which is then used in a bound state calculation to determine the decay rate. Our result for the two-loop correction is 5.1243(33)5.1243(33) in units of (α/π)2(\alpha/\pi)^2 times the lowest order rate. This is consistent with but more precise than the result 5.1(3)5.1(3) of a previous calculation.Comment: 26 pages, 7 figure

    alpha^2 corrections to parapositronium decay: a detailed description

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    We present details of our recent calculation of alpha^2 corrections to the parapositronium decay into two photons. These corrections are rather small and our final result for the parapositronium lifetime agrees well with the most recent measurement. Implications for orthopositronium decays are briefly discussed.Comment: 18 pages, late

    The soft-energy region in the radiative decay of bound states

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    The orthopositronium decay to three photons is studied in the phase-space region where one of the photons has an energy comparable to the relative three-momentum of the e+e- system (w ~ m alpha). The NRQED computation in this regime shows that the dominant contribution arises from distances ~ 1/(mw)^(1/2), which allows to treat the Coulomb interaction perturbatively. The small-photon energy expansion of the 1-loop decay spectrum from full QED yields the same result as the effective theory. By doing the threshold expansion of the 1-loop QED amplitude we confirm that the leading term arises from a loop-momentum region where q^0 ~ q^2/m ~ w. This corresponds to a new non-relativistic loop-momentum region, which has to be taken into account for the description of a non-relativistic particle-antiparticle system that decays through soft photon emission.Comment: 28 pages, 5 figures; typos corrected, one reference added, published versio

    Clinical trial data of anti-PD-1/PD-L1 therapy for recurrent or metastatic nasopharyngeal carcinoma: A review

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    IMPORTANCE: Anti-programmed cell death receptor-1 (PD-1) therapy is standard of care for incurable recurrent or metastatic non-nasopharyngeal head and neck cancer. In contrast, there are no regulatory agency-approved anti-PD-1 agents indicated for the treatment of recurrent or metastatic nasopharyngeal carcinomas (RM-NPC) in the Western hemisphere, and no standard treatment option exists beyond first-line chemotherapy for RM-NPC. The pace of development of novel systemic therapy regimens for RM-NPC has been slow compared to many other advanced tumor types, leaving an unmet clinical need for these patients with a poor prognosis. OBSERVATIONS: Recent clinical trials have documented the clinical activity of anti-PD-1 therapy in RM-NPC. In particular, randomized clinical trials in the first-line setting have demonstrated significant improvements in progression-free survival (PFS) with the addition of anti-PD-1 therapy to standard chemotherapy. Whether the observed PFS benefits require combination chemoimmunotherapy or can be achieved with chemotherapy followed by crossover to immunotherapy upon progression remains unknown. Ongoing clinical trials are exploring novel anti-PD-1 therapy-based combinations, which may further solidify a role for these agents in RM-NPC. CONCLUSIONS AND RELEVANCE: Among patients with RM-NPC, anti-PD-1 therapy added to first-line standard-of-care gemcitabine plus cisplatin provides significantly better efficacy outcomes compared to chemotherapy alone, and anti-PD-1 monotherapy appears to have comparable clinical activity and better tolerability than chemotherapy in previously treated disease. Thus, anti-PD-1 therapy is poised to advance standard of care for the treatment of RM-NPC

    Ulta-slow relaxation in discontinuous-film based electron glasses

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    We present field effect measurements on discontinuous 2D thin films which are composed of a sub monolayer of nano-grains of Au, Ni, Ag or Al. Like other electron glasses these systems exhibit slow conductance relaxation and memory effects. However, unlike other systems, the discontinuous films exhibit a dramatic slowing down of the dynamics below a characteristic temperature T∗T^*. T∗T^* is typically between 10-50K and is sample dependent. For T<T∗T<T^* the sample exhibits a few other peculiar features such as repeatable conductance fluctuations in millimeter size samples. We suggest that the enhanced system sluggishness is related to the current carrying network becoming very dilute in discontinuous films so that the system contains many parts which are electrically very weakly connected and the transport is dominated by very few weak links. This enables studying the glassy properties of the sample as it transitions from a macroscopic sample to a mesocopic sample, hence, the results provide new insight on the underlying physics of electron glasses.Comment: 4 pages, 4 figure

    SU(2) Skyrme Vortices

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    A regular method for constructing vortex-like solutions with cylindrical symmetry to the equations of the SU(2) Skyrme chiral model is proposed. A numerical estimate for the length density of mass is given

    Inhibition of VEGF and Angiopoietin-2 to Reduce Brain Metastases of Breast Cancer Burden

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    For metastases in the central nervous system, angiogenesis enhances metastatic potential and promotes progression. Primary factors which drive vessel growth are vascular endothelial growth factor (VEGF) and angiopoietin-2. Preclinical models show inhibition of either factor reduces metastases spread and inhibits growth. This work sets out to answer two questions in a preclinical mouse model. First, whether the combined inhibition of VEGF and angiopoietin-2, reduces passive permeability and limits drug uptake into brain metastases; and second, whether this inhibition reduces metastases burden in brain. We observed combinatorial inhibition of VEGF and angiopoietin-2, decreased (p \u3c 0.05) angiogenesis and vascular branching in an aortic ring assay and decreased (p \u3c 0.05) endothelial wound closure times. Using a brain metastases of breast cancer model (induced by intracardiac injections of brain seeking MDA-MB-231Br cells or 4T1Br cells), we observed, similar to VEGF, angiopoetin-2 expression correlates to increased angiogenesis (p \u3c 0.05) and increased lesion permeability. To determine efficacy, animals were administered bevacizumab plus L1-10 (angiopoietin inhibitor) twice per week until neurological symptoms developed. Lesion permeability significantly decreased by ∌50% (p \u3c 0.05) compared to untreated lesions, but remained ∌25% greater (p \u3c 0.0%) than brain. In subsequent experiments, animals were administered similar regimens but sacrificed on day 32. The number of metastatic lesions developed was significantly (p \u3c 0.001) reduced in the bevacizumab group (56%) and combination group (86%). Lesions’ size was reduced in bevacizumab treated lesions (∌67%) and bevacizumab and L1-10 treated lesions (∌78%) developing area \u3c 0.5 mm2. In summary, combinatorial inhibition of VEGF and angiopoietin reduces lesion permeability and brain metastatic burden

    The "recoil" correction of order mα6m \alpha^6 to hyperfine splitting of positronium ground state

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    The "recoil" correction of order mα6m \alpha^6 to the hyperfine splitting of positronium ground state was found. The formalism employed is based on the noncovariant perturbation theory in QED. Equation for two-particle component of full (many-body) wave function is used, in which effective Hamiltonian depends on the energy of a system. The effective Hamiltonian is not restricted to the nonrelativistic region, so there is no need in any regularization. To evaluate integrals over loop momenta, they are divided into "hard" and "soft" parts, coming from large and small momenta respectively. Soft contributions were found analytically, and hard ones are evaluated by numerical integration. Some soft terms due to the retardation cancel each other. To calculate the "hard" contributions, a great number of noncovariant graphs is replaced by only a few covariant ones. The hard contribution was found in two ways. The first way is to evaluate contributions of separate graphs, using the Coulomb gauge. The second one is to calculate full hard contribution as a whole using the Feynman gauge. The final result for the "recoil" correction is 0.381(6) m\al^6 and agrees with those of previous papers. Diagram-to-diagram comparison with the revised results of Adkins&Sapirstein was done. All the results agree, so the "recoil" correction is now firmly established. This means a considerable disagreement with the experimental data.Comment: 28 pages, latex including latex figure

    An Expansion Term In Hamilton's Equations

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    For any given spacetime the choice of time coordinate is undetermined. A particular choice is the absolute time associated with a preferred vector field. Using the absolute time Hamilton's equations are −(ÎŽHc)/(ÎŽq)=π˙+Θπ,- (\delta H_{c})/(\delta q)=\dot{\pi}+\Theta\pi, + (\delta H_{c})/(\delta \pi)=\dot{q},where, where \Theta = V^{a}_{.;a}istheexpansionofthevectorfield.Thusthereisahithertounnoticedtermintheexpansionofthepreferredvectorfield.Hamiltonâ€Čsequationscanbeusedtodescribefluidmotion.Inthiscasetheabsolutetimeisthetimeassociatedwiththefluidâ€Čsco−movingvector.Asmeasuredbythisabsolutetimetheexpansiontermispresent.Similarlyincosmology,eachobserverhasaco−movingvectorandHamiltonâ€Čsequationsagainhaveanexpansionterm.ItisnecessarytoincludetheexpansiontermtoquantizesystemssuchastheabovebythecanonicalmethodofreplacingDiracbracketsbycommutators.Hamiltonâ€Čsequationsinthisformdonothaveacorrespondingsympleticform.Replacingtheexpansionbyaparticlenumber is the expansion of the vector field. Thus there is a hitherto unnoticed term in the expansion of the preferred vector field. Hamilton's equations can be used to describe fluid motion. In this case the absolute time is the time associated with the fluid's co-moving vector. As measured by this absolute time the expansion term is present. Similarly in cosmology, each observer has a co-moving vector and Hamilton's equations again have an expansion term. It is necessary to include the expansion term to quantize systems such as the above by the canonical method of replacing Dirac brackets by commutators. Hamilton's equations in this form do not have a corresponding sympletic form. Replacing the expansion by a particle number N\equiv exp(-\int\Theta d \ta)andintroducingtheparticlenumbersconjugatemomentum and introducing the particle numbers conjugate momentum \pi^{N}thestandardsympleticformcanberecoveredwithtwoextrafieldsNand the standard sympletic form can be recovered with two extra fields N and \pi^N$. Briefly the possibility of a non-standard sympletic form and the further possibility of there being a non-zero Finsler curvature corresponding to this are looked at.Comment: 10 page
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