Positive Cross Correlations in a Normal-Conducting Fermionic Beam Splitter

We investigate a beam splitter experiment implemented in a normal conducting fermionic electron gas in the quantum Hall regime. The cross-correlations between the current fluctuations in the two exit leads of the three terminal device are found to be negative, zero or even positive depending on the scattering mechanism within the device. Reversal of the cross-correlations sign occurs due to interaction between different edge-states and does not reflect the statistics of the fermionic particles which `antibunch'.Comment: 4 pages, 4 figure

Breakdown of Universality in Quantum Chaotic Transport: the Two-Phase Dynamical Fluid Model

We investigate the transport properties of open quantum chaotic systems in the semiclassical limit. We show how the transmission spectrum, the conductance fluctuations, and their correlations are influenced by the underlying chaotic classical dynamics, and result from the separation of the quantum phase space into a stochastic and a deterministic phase. Consequently, sample-to-sample conductance fluctuations lose their universality, while the persistence of a finite stochastic phase protects the universality of conductance fluctuations under variation of a quantum parameter.Comment: 4 pages, 3 figures in .eps format; final version to appear in Physical Review Letter

Shot noise of series quantum point contacts intercalating chaotic cavities

Shot noise of series quantum point contacts forming a sequence of cavities in a two dimensional electron gas are studied theoretically and experimentally. Noise in such a structure originates from local scattering at the point contacts as well as from chaotic motion of the electrons in the cavities. We found that the measured shot noise is in reasonable agreement with our theoretical prediction taking the cavity noise into account.Comment: 4 pages, 5 figure

Classical limit of transport in quantum kicked maps

We investigate the behavior of weak localization, conductance fluctuations, and shot noise of a chaotic scatterer in the semiclassical limit. Time resolved numerical results, obtained by truncating the time-evolution of a kicked quantum map after a certain number of iterations, are compared to semiclassical theory. Considering how the appearance of quantum effects is delayed as a function of the Ehrenfest time gives a new method to compare theory and numerical simulations. We find that both weak localization and shot noise agree with semiclassical theory, which predicts exponential suppression with increasing Ehrenfest time. However, conductance fluctuations exhibit different behavior, with only a slight dependence on the Ehrenfest time.Comment: 17 pages, 13 figures. Final versio

Shot Noise by Quantum Scattering in Chaotic Cavities

We have experimentally studied shot noise of chaotic cavities defined by two quantum point contacts in series. The cavity noise is determined as 1/4*2e|I| in agreement with theory and can be well distinguished from other contributions to noise generated at the contacts. Subsequently, we have found that cavity noise decreases if one of the contacts is further opened and reaches nearly zero for a highly asymmetric cavity.Comment: 4 pages, 4 figures, REVTe

The L&E of Intellectual Property – Do we get maximum innovation with the current regime?

Innovation is crucial to economic growth – the essential path for lifting much of the world population out of dire poverty and for maintaining the living standard of those who already have. To stimulate innovation, the legal system has to support the means through which innovators seek to get rewarded for their efforts. Amongst these means, some, such as the first mover advantage or 'lead time,' are not directly legal; but secrets and intellectual property rights are legal institutions supported for the specific purpose of stimulating innovation. Whilst the protection of secrets has not changed very much over recent years, intellectual property (or IP) has. IP borrows some features from ordinary property rights, but is also distinct, in that, unlike physical goods, information, the object of IP, is not inherently scarce; indeed as information and communication technologies expand, the creation and distribution of information is becoming ever cheaper and in many circumstances abundant, so that selection is of the essence ('on the internet, point of view is everything'). Where rights on information extend too far, their monopolising effect may hamper innovation. The paper investigates the underlying structure of IP rights and surveys what we know empirically about the incentive effects of IP as about industries that flourish without formal IP

Shot noise in ferromagnet--normal metal systems

A semiclassical theory of the low frequency shot noise in ferromagnet - normal metal systems is formulated. Non-collinear magnetization directions of the ferromagnetic leads, arbitrary junctions and the elastic and inelastic scattering regimes are considered. The shot noise is governed by a set of mesoscopic parameters that are expressed in terms of the microscopic details of the junctions in the circuit. Explicit results in the case of ballistic, tunnel, and diffusive junctions are evaluated. The shot noise, the current and the Fano factor are calculated for a double barrier ferromagnet - normal metal - ferromagnet system. It is demonstrated that the shot noise can have a non-monotonic behavior as a function of the relative angle between the magnetizations of the ferromagnetic reservoirs.Comment: 17 pages, 7 figure

Implication of Mitochondrial Cytoprotection in Human Islet Isolation and Transplantation

Islet transplantation is a promising therapy for type 1 diabetes mellitus; however, success rates in achieving both short- and long-term insulin independence are not consistent, due in part to inconsistent islet quality and quantity caused by the complex nature and multistep process of islet isolation and transplantation. Since the introduction of the Edmonton Protocol in 2000, more attention has been placed on preserving mitochondrial function as increasing evidences suggest that impaired mitochondrial integrity can adversely affect clinical outcomes. Some recent studies have demonstrated that it is possible to achieve islet cytoprotection by maintaining mitochondrial function and subsequently to improve islet transplantation outcomes. However, the benefits of mitoprotection in many cases are controversial and the underlying mechanisms are unclear. This article summarizes the recent progress associated with mitochondrial cytoprotection in each step of the islet isolation and transplantation process, as well as islet potency and viability assays based on the measurement of mitochondrial integrity. In addition, we briefly discuss immunosuppression side effects on islet graft function and how transplant site selection affects islet engraftment and clinical outcomes

The 1/3-shot noise suppression in diffusive nanowires

We report low-temperature shot noise measurements of short diffusive Au wires attached to electron reservoirs of varying sizes. The measured noise suppression factor compared to the classical noise value $2e\left| I\right|$ strongly depends on the electric heat conductance of the reservoirs. For small reservoirs injection of hot electrons increases the measured noise and hence the suppression factor. The universal 1/3-suppression factor can only asymptotically be reached for macroscopically large and thick electron reservoirs. A heating model based on the Wiedemann-Franz law is used to explain this effect.Comment: 10 figure

Univariate and multivariate GARCH models applied to the CARBS indices

Abstract: The purpose of this paper is to estimate the calibrated parameters of different univariate and multivariate GARCH family models. It is unrealistic to assume that volatility of financial returns is constant. In the empirical analysis, the symmetric GARCH, and asymmetric GJR-GARCH and EGARCH models were estimated for the CARBS indices and a global minimum variance portfolio (GMVP), the best fitting model was determined using the AIC and BIC. The asymmetric terms of the GJR-GARCH and EGARCH models indicate signs of the leverage effect. The information criterion suggest that the EGARCH model is the best fitting model for the CARBS indices and the GMVP