372 research outputs found

    Detection of non-Gaussian Fluctuations in a Quantum Point Contact

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    An experimental study of current fluctuations through a tunable transmission barrier, a quantum point contact, are reported. We measure the probability distribution function of transmitted charge with precision sufficient to extract the first three cumulants. To obtain the intrinsic quantities, corresponding to voltage-biased barrier, we employ a procedure that accounts for the response of the external circuit and the amplifier. The third cumulant, obtained with a high precision, is found to agree with the prediction for the statistics of transport in the non-Poissonian regime.Comment: 4 pages, 4 figures; published versio

    Measurement of Counting Statistics of Electron Transport in a Tunnel Junction

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    We present measurements of the time-dependent fluctuations in electrical current in a voltage-biased tunnel junction. We were able to simultaneously extract the first three moments of the tunnel current counting statistics. Detailed comparison of the second and the third moment reveals that counting statistics is accurately described by the Poissonian distribution expected for spontaneous current fluctuations due to electron charge discreteness, realized in tunneling transport at negligible coupling to environment.Comment: bibliography expande

    Endothelioprotective property of the combination of the thioctic acid and rosuvastatin shown in the endothelial dysfunction models

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    During the experiment, the modeling of endothelial dysfunction of male rats was performed by intraperitoneal administration of L-NAME at a dose of 25 mg/kg for 7 days, and the same of female rats was performed by bilateral ovarioectomy and further intraperitoneal administration of L-NAME at a dose of 25 mg/kg for 7. The deficiency of nitric oxide as a result of the NO-synthase blockade was accompanied by the impairment of the endotheliumdependent and independent vasodilatation estimated in the pharmacological tests, which was expressed in the increasing coefficient of endothelial dysfunctio

    Electron shot noise beyond the second moment

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    The form of electron counting statistics of the tunneling current noise in a generic many-body interacting electron system is obtained. The third correlator of current fluctuations (the skewness of the charge counting distribution) has a universal relation with the current I and the quasiparticle charge q. This relation C_3 = q^2 I holds in a wide bias voltage range, both at large and small eV/kT, thereby representing an advantage compared to the Schottky formula. We consider the possibility of using the counting statistics for detecting quasiparticle charge at high temperature.Comment: 4 pages, 2 figure

    Regulating Access to Adult Content (with Privacy Preservation)

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    In the physical world we have well-established mechanisms for keeping children out of adult-only areas. In the virtual world this is generally replaced by self declaration. Some service providers resort to using heavy-weight identification mechanisms, judging adulthood as a side effect thereof. Collection of identification data arguably constitutes an unwarranted privacy invasion in this context, if carried out merely to perform adulthood estimation. This paper presents a mechanism that exploits the adult's more extensive exposure to public media, relying on the likelihood that they will be able to recall details if cued by a carefully chosen picture. We conducted an online study to gauge the viability of this scheme. With our prototype we were able to predict that the user was a child 99% of the time. Unfortunately the scheme also misclassified too many adults. We discuss our results and suggest directions for future research

    The design and in vivo testing of a locally stiffness-matched porous scaffold

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    An increasing volume of work supports utilising the mechanobiology of bone for bone ingrowth into a porous scaffold. However, typically during in vivo testing of implants, the mechanical properties of the bone being replaced are not quantified. Consequently there remains inconsistencies in the literature regarding ‘optimum’ pore size and porosity for bone ingrowth. It is also difficult to compare ingrowth results between studies and to translate in vivo animal testing to human subjects without understanding the mechanical environment. This study presents a clinically applicable approach to determining local bone mechanical properties and design of a scaffold with similar properties. The performance of the scaffold was investigated in vivo in an ovine model. The density, modulus and strength of trabecular bone from the medial femoral condyle from ovine bones was characterised and power-law relationships were established. A porous titanium scaffold, intended to maintain bone mechanical homeostasis, was additively manufactured and implanted into the medial femoral condyle of 6 ewes. The stiffness of the scaffold varied throughout the heterogeneous structure and matched the stiffness variation of bone at the surgical site. Bone ingrowth into the scaffold was 10.73 ± 2.97% after 6 weeks. Fine woven bone, in the interior of the scaffold, and intense formations of more developed woven bone overlaid with lamellar bone at the implant periphery were observed. The workflow presented will allow future in vivo testing to test specific bone strains on bone ingrowth in response to a scaffold and allow for better translation from in vivo testing to commercial implants

    Full counting statistics of a chaotic cavity with asymmetric leads

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    We study the statistics of charge transport in a chaotic cavity attached to external reservoirs by two openings of different size which transmit non-equal number of quantum channels. An exact formula for the cumulant generating function has been derived by means of the Keldysh-Green function technique within the circuit theory of mesoscopic transport. The derived formula determines the full counting statistics of charge transport, i.e., the probability distribution and all-order cumulants of current noise. It is found that, for asymmetric cavities, in contrast to other mesoscopic systems, the third-order cumulant changes the sign at high biases. This effect is attributed to the skewness of the distribution of transmission eigenvalues with respect to forward/backward scattering. For a symmetric cavity we find that the third cumulant approaches a voltage-independent constant proportional to the temperature and the number of quantum channels in the leads.Comment: new section on probability distribution and new references adde

    Observation of structures at 17\sim 17 and 38\sim 38 MeV/c2^{2} in the γγ\gamma\gamma invariant mass spectra in pC, dC, and dCu collisions at plab\textit{p}_{lab} of a few GeV/c per nucleon

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    The results of an analysis of the invariant mass spectra of photon pairs produced in dC, pC and dCu interactions at momenta of 2.75, 5.5 and 3.83 GeV/c per nucleon respectively, are presented. Signals in the form of enhanced structures at invariant masses of about 17 and 38 MeV/c2 are observed. The results of testing of the observed signals, including the results of the Monte Carlo simulation are presented. The test results support the conclusion that the observed signals are the consequence of detection of the particles with masses of about 17 and 38 MeV/c2 decaying into a pair of photons.Comment: arXiv admin note: text overlap with arXiv:0806.279

    ~115 GeV and ~143 GeV Higgs mass considerations within the Composite Particles Model

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    The radiatively generated Higgs mass is obtained by requiring that leading "divergences" are cancelled in both 2D and 4D. This predicts one or more viable modes; the k=1 mode mass is m_H\cong2/3 m_t\cong115GeV whereas the k=2 mode is m_H\cong143GeV. These findings are interpreted within the Composite Particles Model (CPM), [Popovic 2002, 2010], with the massive top quark being a composite structure composed of 3 fundamental O quarks (O\bar{O}O) and the massive Higgs scalar being a color-neutral meson like structure composed of 2 fundamental O quarks (\bar{O}O). The CPM predicts that the Z mass generation is mediated primarily by a top - anti top whereas the Higgs mass is generated primarily by a O - anti O interactions. The relationship [Popovic 2010] between top Yukawa coupling and strong QCD coupling, obtained by requiring that top - anti top channel is neither attractive or repulsive at tree level at \surd s\congM_Z, defines the Z mass. In addition, this relationship indirectly defines the electroweak symmetry breaking (EWSB) vacuum expectation value (VEV), the CPM Higgs mass and potentially the EWSB scale.Comment: 11 pages, 3 figures, slightly updated second version: Lagrangian explicitly specified, OOO->O\bar{O}O and a few other typos correcte
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