Flight measurement and analysis of AAFE RADSCAT wind speed signature of the ocean

The advanced aerospace flight experiment radiometer scatterometer (AAFE RADSCAT) which was developed as a research tool to evaluate the use of microwave frequency remote sensors to provide wind speed information at the ocean surface is discussed. The AAFE RADSCAT helped establish the feasibility of the satellite scatterometer for measuring both wind speed and direction. The most important function of the AAFE RADSCAT was to provide a data base of ocean normalized radar cross section (NRCS) measurements as a function of surface wind vector at 13.9 GHz. The NRCS measurements over a wide parametric range of incidence angles, azimuth angles, and winds were obtained in a series of RADSCAT aircraft missions. The obtained data base was used to model the relationship between k sub u band radar signature and ocean surface wind vector. The models developed therefrom are compared with those used for inversion of the SEASAT-A satellite scatterometer (SASS) radar measurements to wind speeds

Complete Insecurity of Quantum Protocols for Classical Two-Party Computation

A fundamental task in modern cryptography is the joint computation of a function which has two inputs, one from Alice and one from Bob, such that neither of the two can learn more about the other's input than what is implied by the value of the function. In this Letter, we show that any quantum protocol for the computation of a classical deterministic function that outputs the result to both parties (two-sided computation) and that is secure against a cheating Bob can be completely broken by a cheating Alice. Whereas it is known that quantum protocols for this task cannot be completely secure, our result implies that security for one party implies complete insecurity for the other. Our findings stand in stark contrast to recent protocols for weak coin tossing, and highlight the limits of cryptography within quantum mechanics. We remark that our conclusions remain valid, even if security is only required to be approximate and if the function that is computed for Bob is different from that of Alice.Comment: v2: 6 pages, 1 figure, text identical to PRL-version (but reasonably formatted

On the power of two-party quantum cryptography

We study quantum protocols among two distrustful parties. Under the sole assumption of correctness - guaranteeing that honest players obtain their correct outcomes - we show that every protocol implementing a non-trivial primitive necessarily leaks information to a dishonest player. This extends known impossibility results to all non-trivial primitives. We provide a framework for quantifying this leakage and argue that leakage is a good measure for the privacy provided to the players by a given protocol. Our framework also covers the case where the two players are helped by a trusted third party. We show that despite the help of a trusted third party, the players cannot amplify the cryptographic power of any primitive. All our results hold even against quantum honest-but-curious adversaries who honestly follow the protocol but purify their actions and apply a different measurement at the end of the protocol. As concrete examples, we establish lower bounds on the leakage of standard universal two-party primitives such as oblivious transfer

Model-based Cognitive Neuroscience: Multifield Mechanistic Integration in Practice

Autonomist accounts of cognitive science suggest that cognitive model building and theory construction (can or should) proceed independently of findings in neuroscience. Common functionalist justifications of autonomy rely on there being relatively few constraints between neural structure and cognitive function (e.g., Weiskopf, 2011). In contrast, an integrative mechanistic perspective stresses the mutual constraining of structure and function (e.g., Piccinini & Craver, 2011; Povich, 2015). In this paper, I show how model-based cognitive neuroscience (MBCN) epitomizes the integrative mechanistic perspective and concentrates the most revolutionary elements of the cognitive neuroscience revolution (Boone & Piccinini, 2016). I also show how the prominent subset account of functional realization supports the integrative mechanistic perspective I take on MBCN and use it to clarify the intralevel and interlevel components of integration

Implications of Hyperon Pairing for Cooling of Neutron Stars

The implications of hyperon pairing for the thermal evolution of neutron stars containing hyperons are investigated. The outcome of cooling simulations are compared for neutron star models composed only of nucleons and leptons, models including hyperons, and models including pairing of hyperons. We show that lambda and neutron pairing suppresses all possible fast neutrino emission processes in not too massive neutron stars. The inclusion of lambda pairing yields better agreement with X-ray observations of pulsars. Particularly, the surface temperatures deduced from X-ray observations within the hydrogen atmosphere model are more consistent with the thermal history of neutron stars containing hyperons, if the critical temperature for the onset of lambda and nucleon pairing is not too small.Comment: 7 pages, 3 figures. To be published in ApJL. The postscript and additional tables can be found at http://www.physik.uni-muenchen.de/sektion/suessmann/astro/cool/schaab.089

Magnetic field generated by r-modes in accreting quark stars

We show that the r-mode instability can generate strong toroidal fields in the core of accreting millisecond quark stars by inducing differential rotation. We follow the spin frequency evolution on a long time scale taking into account the magnetic damping rate in the evolution equations of r-modes. The maximum spin frequency of the star is only marginally smaller than in the absence of the magnetic field. The late-time evolution of the stars which enter the r-mode instability region is instead rather different if the generated magnetic fields are taken into account: they leave the millisecond pulsar region and they become radio pulsars.Comment: 8 pages, 8 figure

Cryptography in the Bounded Quantum-Storage Model

We initiate the study of two-party cryptographic primitives with unconditional security, assuming that the adversary’s quantum memory is of bounded size. We show that oblivious transfer and bit commitment can be implemented in this model using protocols where honest parties need no quantum memory, whereas an adversarial player needs quantum memory of size at least n/2 in order to break the protocol, where n is the number of qubits transmitted. This is in sharp contrast to the classical bounded-memory model, where we can only tolerate adversaries with memory of size quadratic in honest players’ memory size. Our protocols are efficient and noninteractive and can be implemented using today’s technology. On the technical side, a new entropic uncertainty relation involving min-entropy is established

Improving the security of quantum protocols via commit-and-open

We consider two-party quantum protocols starting with a transmission of some random BB84 qubits followed by classical messages. We show a general compiler improving the security of such protocols: if the original protocol is secure against an almost honest adversary, then the compiled protocol is secure against an arbitrary computationally bounded (quantum) adversary. The compilation preserves the number of qubits sent and the number of rounds up to a constant factor. The compiler also preserves security in the bounded-quantum-storage model (BQSM), so if the original protocol was BQSM-secure, the compiled protocol can only be broken by an adversary who has large quantum memory and large computing power. This is in contrast to known BQSM-secure protocols, where security breaks down completely if the adversary has larger quantum memory than expected. We show how our technique can be applied to quantum identification and oblivious transfer protocols