A proposal for founding mistrustful quantum cryptography on coin tossing

A significant branch of classical cryptography deals with the problems which arise when mistrustful parties need to generate, process or exchange information. As Kilian showed a while ago, mistrustful classical cryptography can be founded on a single protocol, oblivious transfer, from which general secure multi-party computations can be built. The scope of mistrustful quantum cryptography is limited by no-go theorems, which rule out, inter alia, unconditionally secure quantum protocols for oblivious transfer or general secure two-party computations. These theorems apply even to protocols which take relativistic signalling constraints into account. The best that can be hoped for, in general, are quantum protocols computationally secure against quantum attack. I describe here a method for building a classically certified bit commitment, and hence every other mistrustful cryptographic task, from a secure coin tossing protocol. No security proof is attempted, but I sketch reasons why these protocols might resist quantum computational attack.Comment: Title altered in deference to Physical Review's fear of question marks. Published version; references update

Two-measured variable method for wall interference assessment/correction

An iterative method for wall interference assessment and/or correction is presented for transonic flow conditions in wind tunnels equipped with two component velocity measurements on a single interface. The iterative method does not require modeling of the test article and tunnel wall boundary conditions. Analytical proof for the convergence and stability of the iterative method is shown in the subsonic flow regime. The numerical solutions are given for both 2-D and axisymmetrical cases at transonic speeds with the application of global Mach number correction

A wall interference assessment/correction system

The Hackett method (a Wall Pressure Signature Method) was selected to be adapted for the 12 ft Wind Tunnel WIAC system. This method uses limited measurements of the static pressure at the wall, in conjunction with the solid wall boundary condition, to determine the strength and distribution of singularities representing the test article. The singularities are used in term for estimating wall interference at the model location. Hackett's method will have to be formulated for application to the unique geometry of the 12 ft tunnel. The WIAC code will be validated by conducting numerically simulated experiments rather than actual wind tunnel experiments. The simulations will be used to generate both free air and confined wind tunnel flow fields for each of the test articles over a range of test configurations. Specifically the pressure signature at the test section wall will be computed for the confined case to provide the simulated 'measured' data. These data will serve as the input for the WIAC method. The performance of the WIAC method then may be evaluated by comparing the corrected parameters with those for the free air simulation

Wake states and frequency selection of a streamwise oscillating cylinder

This paper presents the results of an in-depth study of the flow past a streamwise oscillating cylinder, examining the impact of varying the amplitude and frequency of the oscillation, and the Reynolds number of the incoming flow. These findings are presented in a framework that shows that the relationship between the frequency of vortex shedding fs and the amplitude of oscillation A* is governed by two primary factors: the first is a reduction of fs proportional to a series in A*2 over a wide range of driving frequencies and Reynolds numbers; the second is nonlinear synchronization when this adjusted fs is in the vicinity of N = (1 - fs/fd)-1, where N is an integer. Typically, the influence of higher-order terms is small, and truncation to the first term of the series (A*2) well represents the overall trend of vortex shedding frequency as a function of amplitude. However, discontinuous steps are overlaid on this trend due to the nonlinear synchronization. When fs is normalized by the Strouhal frequency fSt (the frequency of vortex shedding from an unperturbed cylinder), the rate at which fs/fSt decreases with amplitude, at least for fd/fSt = 1, shows a linear dependence on the Reynolds number. For a fixed Re = 175, the truncated series shows that the rate of decrease of fs/fSt with amplitude varies as (2 - fd/fSt)-1/2 for 1 < or egal fd/fSt < or egal 2, but is essentially independent of fd/fSt for fd/fSt < 1. These trends of the rate of decrease of fs with respect to amplitude are also used to predict the amplitudes of oscillation around which synchronization occurs. These predicted amplitudes are shown to fall in regions of the parameter space where synchronized modes occur. Further, for the case of varying fd/fSt, a very reasonable prediction of the amplitude of oscillation required for the onset of synchronization to the mode where fs = 0.5fd is given. In a similar manner, amplitudes at which fs = 0 are calculated, predicting where the natural vortex shedding is completely supplanted by the forcing. These amplitudes are found to coincide approximately with those at which the onset of a symmetric vortex shedding mode is observed. This result is interpreted as meaning that the symmetric shedding mode occurs when the dynamics crosses over from being dominated by the vortex shedding to being dominated by the forcing

A numerical study of an inline oscillating cylinder in a free stream

Simulations of a cylinder undergoing externally controlled sinusoidal oscillations in the free stream direction have been performed. The frequency of oscillation was kept equal to the vortex shedding frequency from a fixed cylinder, while the amplitude of oscillation was varied, and the response of the flow measured. With varying amplitude, a rich series of dynamic responses was recorded. With increasing amplitude, these states included wakes similar to the Kármán vortex street, quasiperiodic oscillations interleaved with regions of synchronized periodicity (periodic on multiple oscillation cycles), a period-doubled state and chaotic oscillations. It is hypothesized that, for low to moderate amplitudes, the wake dynamics are controlled by vortex shedding at a global frequency, modified by the oscillation. This vortex shedding is frequency modulated by the driven oscillation and amplitude modulated by vortex interaction. Data are presented to support this hypothesis

Mitochondrial heteroplasmy in an avian hybrid form (Passer italiae: Aves, Passeriformes)

Mitochondrial heteroplasmy is the result from biparental transmission of mitochondrial DNA (mtDNA) to the offspring. In such rare cases, maternal and paternal mtDNA is present in the same individual. Though recent studies suggested that mtDNA heteroplasmy might be more common than previously anticipated, that phenomenon is still poorly documented and was mostly detected in case studies on hybrid populations. The Italian sparrow, Passer italiae is a homoploid hybrid form that occurs all across the Italian Peninsula mostly under strict absence of either of its parent species, the house sparrow (P. domesticus) and the Spanish sparrow (P. hispaniolensis). In this study, we document a new case of mitochondrial heteroplasmy from two island populations of P. italiae (Ustica and Lipari). Our analysis was based on the mitochondrial NADH dehydrogenase subunit 2 (ND2) that allows for a clear distinction between mitochondrial lineages of the two parental species. We amplified and sequenced the mitochondrial ND2 gene with specifically designed primer combinations for each of the two parental species. In two of our study populations, a single individual carried two different ND2 haplotypes from each of the two parental lineages. These findings contribute to current knowledge on the still poorly documented phenomenon of paternal leakage in vertebrates

Flow over a cylinder subjected to combined translational and rotational oscillations

The experimental research reported here employs particle image velocimetry to extend the study of Nazarinia et al. (2009a), recording detailed vorticity fields in the near-wake of a circular cylinder undergoing combined translational and rotational oscillatory motions. The focus of the present study is to examine the effect of the ratio between the cross-stream translational and rotational velocities and frequencies on the synchronization of the near- wake structures for multiple phase differences between the two motions. The frequencies are fixed close to that of the natural frequency of vortex shedding. The results are presented for a fixed amplitude of rotational oscillation of 1 rad and a range of ratios between the translational and rotational velocities ðVRÞ 1⁄4 1⁄20:25,0:5,1:0,1:

No Superluminal Signaling Implies Unconditionally Secure Bit Commitment

Bit commitment (BC) is an important cryptographic primitive for an agent to convince a mutually mistrustful party that she has already made a binding choice of 0 or 1 but only to reveal her choice at a later time. Ideally, a BC protocol should be simple, reliable, easy to implement using existing technologies, and most importantly unconditionally secure in the sense that its security is based on an information-theoretic proof rather than computational complexity assumption or the existence of a trustworthy arbitrator. Here we report such a provably secure scheme involving only one-way classical communications whose unconditional security is based on no superluminal signaling (NSS). Our scheme is inspired by the earlier works by Kent, who proposed two impractical relativistic protocols whose unconditional securities are yet to be established as well as several provably unconditionally secure protocols which rely on both quantum mechanics and NSS. Our scheme is conceptually simple and shows for the first time that quantum communication is not needed to achieve unconditional security for BC. Moreover, with purely classical communications, our scheme is practical and easy to implement with existing telecom technologies. This completes the cycle of study of unconditionally secure bit commitment based on known physical laws.Comment: This paper has been withdrawn by the authors due to a crucial oversight on an earlier work by A. Ken

Evaluation of the amperex 56 TVP photomultiplier

Characteristics were measured for the Amperex 56 TVP 42 mm-diameter photomultiplier. Some typical photomultiplier characteristics-such as gain, dark current, transit and rise times-are compared with data provided. Photomultiplier characteristics generally not available such as the single photoelectron time spread, the relative collection efficiency, the relative anode pulse amplitude as a function of the voltage between the photocathode and focusing electrode, and the position of the photocathode sensing area were measured and are discussed for two 56 TVP's. The single photoelectron time spread, the relative collection efficiency, and the transit time difference as a function of the voltage between photocathode and focusing electrode were also measured and are discussed, particularly with respect to the optimization of photomultiplier operating conditions for timing applications