3,443 research outputs found

    Azimuthally unidirectional transport of energy in magnetoelectric fields. Topological Lenz effect

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    Magnetic dipolar modes (MDMs) in a quasi 2D ferrite disk are microwave energy eigenstate oscillations with topologically distinct structures of rotating fields and unidirectional power flow circulations. At the first glance, this might seem to violate the law of conservation of an angular momentum, since the microwave structure with an embedded ferrite sample is mechanically fixed. However, an angular momentum is seen to be conserved if topological properties of electromagnetic fields in the entire microwave structure are taken into account. In this paper we show that due to the topological action of the azimuthally unidirectional transport of energy in a MDM resonance ferrite sample there exists the opposite topological reaction on a metal screen placed near this sample. We call this effect topological Lenz effect. The topological Lenz law is applied to opposite topological charges, one in a ferrite sample and another on a metal screen. The MDM originated near fields, the magnetoelectric (ME) fields, induce helical surface electric currents and effective charges on a metal. The fields formed by these currents and charges will oppose their cause

    The ethics of donation and transplantation: are definitions of death being distorted for organ transplantation?

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    A recent commentary defends 1) the concept of 'brain arrest' to explain what brain death is, and 2) the concept that death occurs at 2–5 minutes after absent circulation. I suggest that both these claims are flawed. Brain arrest is said to threaten life, and lead to death by causing a secondary respiratory then cardiac arrest. It is further claimed that ventilation only interrupts this way that brain arrest leads to death. These statements imply that brain arrest is not death itself. Brain death is a devastating state that leads to death when intensive care, which replaces some of the brain's vital functions such as breathing, is withdrawn and circulation stops resulting in irreversible loss of integration of the organism. Circulatory death is said to occur at 2–5 minutes after absent circulation because, in the context of DCD, the intent is to not attempt reversal of the absent circulation. No defense of this weak construal of irreversible loss of circulation is given. This means that paents in identical physiologic states are dead (in the DCD context) or alive (in the resuscitation context); the current state of death (at 2–5 minutes) is contingent on a future event (whether there will be resuscitation) suggesting backward causation; and the commonly used meaning of irreversible as 'not capable of being reversed' is abandoned. The literature supporting the claim that autoresuscitation does not occur in the context of no cardiopulmonary resuscitation is shown to be very limited. Several cases of autoresuscitation are summarized, suggesting that the claim that these cases are not applicable to the current debate may be premature. I suggest that brain dead and DCD donors are not dead; whether organs can be harvested before death from these patients whose prognosis is death should be debated urgently

    Model of the mechanical response of short flax fiber reinforced polymer matrix composites

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    AbstractNatural-fiber-reinforced short-fiber composites are finding more applications lately, therefore there is a need for estimation of the mechanical properties of such composites based on the properties of the constituents. The fibers themselves also possess complicated internal structure, resulting in anisotropy of their properties. Taking into account the internal structure of bast fiber, we evaluate the elastic properties of a composite unit cell, consisting of a fiber of average length and matrix according to the fiber volume fraction in the composite. The unit cell properties are used to estimate the stiffness of a misaligned short-fiber composite by means of orientation averaging. The results obtained are compared with the experimental stress-strain diagrams of short flax fiber/polypropylene matrix composite. Usually the mechanical response of short-fiber/polymer matrix composite is non-linear due to the inelastic matrix behavior. Accounting for the non-linear deformation of the matrix in the unit cell by modeling it as an elastic-plastic material, we also estimate its non-linear response under uniaxial loading

    Inclusive cross sections for pairs of identified light charged hadrons and for single protons in e^{+}e^{-} at sqrt[s]=10.58GeV

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    We report the first double differential cross sections of two charged pions and kaons (e+e−→hhX) in electron-positron annihilation as a function of the fractional energies of the two hadrons for any charge and hadron combination. The dependence of these dihadron cross sections on the topology (same, opposite hemisphere or anywhere) is also studied with the help of the event shape variable thrust and its axis. The ratios of these dihadron cross sections for different charges and hadron combinations directly shed light on the contributing fragmentation functions. For example, we find that the ratio of same-sign pion pairs over opposite-sign pion pairs drops toward higher fractional energies where disfavored fragmentation is expected to be suppressed. These dihadron results are obtained from a 655  fb−1 data sample collected near the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. Extending the previously published single-pion and single-kaon cross sections, single-proton (e+e−→pX) cross sections are extracted from a 159  fb−1 data subsample

    Treatment of severe parkinsonism with L-Dopa

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    The beneficial effect of L-dopa in the treatment of Parkinson's disease is confirmed, although the success rate was slightly lower than reported in other studies. This can be explained by the fact that only elderly and very severely disabled patients were treated. Akinesia and rigidity were the symptoms which responded best to this form of treatment. Tremor responded poorly and most of the therapeutic failures were in patients where tremor was the major complaint. It is possible that this symptom may respond to very much larger doses

    Measurement of the decay B→Dℓν_{ℓ} in fully reconstructed events and determination of the Cabibbo-Kobayashi-Maskawa matrix element |V_{cb}|

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    We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| using the decay B→Dℓνℓ (ℓ=e,μ) based on 711 fb−1 of e+e−→Υ(4S) data recorded by the Belle detector and containing 772×106 B¯B pairs. One B meson in the event is fully reconstructed in a hadronic decay mode, while the other, on the signal side, is partially reconstructed from a charged lepton and either a D+ or D0 meson in a total of 23 hadronic decay modes. The isospin-averaged branching fraction of the decay B→Dℓνℓ is found to be B(B0→D−ℓ+νℓ)=(2.31±0.03(stat)±0.11(syst))%. Analyzing the differential decay rate as a function of the hadronic recoil with the parametrization of Caprini, Lellouch, and Neubert and using the form-factor prediction G(1)=1.0541±0.0083 calculated by FNAL/MILC, we obtain ηEW|Vcb|=(40.12±1.34)×10−3, where ηEW is the electroweak correction factor. Alternatively, assuming the model-independent form-factor parametrization of Boyd, Grinstein, and Lebed and using lattice QCD data from the FNAL/MILC and HPQCD collaborations, we find ηEW|Vcb|=(41.10±1.14)×10−3
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