Oblivious Transfers and Privacy Amplification

Oblivious transfer (OT) is an important primitive in cryptography. In chosen one-out-of-two string OT, a sender offers two strings, one of which the other party, called the receiver, can choose to read, not learning any information about the other string. The sender on the other hand does not obtain any information about the receivers choice. We consider the problem of reducing this primitive to OT for single bits. Previous attempts to doing this were based on self-intersecting codes. We present a new technique for the same task, based on so-called privacy amplification. It is shown that our method has two important advantages over the previous approaches. First, it is more efficient in terms of the number of required realizations of bit OT, and second, the technique even allows for reducing string OT to (apparently) much weaker primitives. An example of such a primitive is universal OT, where the receiver can adaptively choose what type of information he wants to obtain about the two bits sent by the sender subject to the only constraint that some, possibly very small, uncertainty must remain about the pair of bits.     

Quantum speed-up for unsupervised learning

We show how the quantum paradigm can be used to speed up unsupervised learning algorithms. More precisely, we explain how it is possible to accelerate learning algorithms by quantizing some of their subroutines. Quantization refers to the process that partially or totally converts a classical algorithm to its quantum counterpart in order to improve performance. In particular, we give quantized versions of clustering via minimum spanning tree, divisive clustering and k-medians that are faster than their classical analogues. We also describe a distributed version of k-medians that allows the participants to save on the global communication cost of the protocol compared to the classical version. Finally, we design quantum algorithms for the construction of a neighbourhood graph, outlier detection as well as smart initialization of the cluster centres.     

Two antipeptide monoclonal antibodies that recognize adhesive sequences in fibrinogen: identification of antigenic determinants and unrelated sequences using synthetic combinatorial libraries

Fulminant hepatic failure is infrequently seen as a consequence of acute congestive heart failure. Recognition of this entity is important as treatment directed towards heart failure should help resolve the liver failure. A case of fulminant hepatic failure due to previously unrecognized cardiomyopathy is presented. A liver transplantation was being considered for fulminant hepatic failure until hemodynamic monitoring studies demonstrated that, in fact, the patient had severe cardiomyopathy. Treatment directed at his cardiomyopathy resolved the liver failure. Therefore, prompt recognition of such a phenomenon would enable early institution of appropriate therapeutic measures with the hope of clinical benefit to the patient.     

Measurement of the depth distribution of light impurities in first-wall materials: He in Nb

We have measured the concentrations and depth profiles of implanted helium in niobium by a method demonstrated previously with hydrogen and lithium in copper. The three targets, bombarded at room temperature with 10 keV He⁺ at doses of 0.01, 0.16 and 0.98 C/cm⁺, were respectively: unblistered; covered with circular blisters; and marked with “microrelief”, without blisters. The corresponding doses retained in the metal were 0.0076, 0.039 and 0.052 C/cm² (i.e.≈3 × 10²² He atoms/cm³) with a 10% normalization uncertainty. The profile shapes did not change much: in particular we did not observe, as the dose increased, an accumulation near the surface, which is receding by erosion (sputtering, blistering). These results show that a mechanism of helium loss starts operating at a dose ?0.16 C/cm², i.e. before the bursting of blisters (if they burst at all), and it is most effective near the surface.     

A time-luck tradeoff in relativized cryptography

New definitions are proposed for the security of Transient-Key Cryptography (a variant on Public-Key Cryptography) that account for the possibility of super-polynomial-time Monte Carlo cryptanalytical attacks. Weaker definitions no longer appear to be satisfactory in the light of Adleman's recent algorithm capable of breaking the Diffie-Hellman scheme in RTIME(O(2^{0(√n log n)})) for keys of length n. The basic question we address is: How can one relate the amount of time a cryptanalyst is willing to spend decoding cryptograms to his likelihood of success? What more can one say than the obvious “The more time he uses, the less lucky he needs to be?” These questions and others are partially answered in a relativized model of computation in which there exists a transient-key cryptosystem such that even a cryptanalyst willing to spend as much as (almost) O(2^{n/log n}) steps on length n cryptograms cannot hope to break but an exponentially small fraction of them, even if he is allowed to make use of a true random number generator. This is rather tight because the same cryptosystem falls immediately if the cryptanalyst is willing to spend O(2^cn) steps for any constant c > 0.     

Impact of aluminium pad and operation parameters on graphitised and graphitic cathodes expansion and bath penetration

Cathode sodium expansion and bath penetration are important properties to consider in the Hall–Héroult process. Rapoport test is the standard method for sodium expansion determination. However, there is no standard methodology for bath diffusion measurement. In this work, expansion measurements are achieved on laboratory scale alumina reduction cells for graphitic and graphitised cathode block grades. Cathode carrots were then extracted to measure bath penetration. Results revealed that the presence of an aluminium pad at the beginning of the experiment has reduced the sodium expansion and bath penetration by about 50%. Sodium concentration in the bath has increased the expansion rate and bath penetration depth, but not the expansion level, which is driven by the current density. This demonstrates that the startup conditions are crucial to the lifespan of the electrolysis cell.     

élaboration et validation du Questionnaire de Soutien Conjugal (QSC).

Although partner support represents a significant source of help amongst people (Beach, Fincham, Katz, & Bradbury, 1996; Cutrona, 1996), few valid and reliable measures of couple support are available. The current study presents the elaboration and validation of the “Questionnaire de soutien conjugal” (QSC), a brief measure evaluating given and received support within conjugal relationship. A sample of 270 French-Canadian couples completed the QSC and a short version of the Dyadic Adjustment Scale (Spanier, 1976; Sabourin, Valois, & Lussier, 2005). One year later, 160 couples agreed to complete the same measures again. Exploratory Factor Analyses supported the two-factor structure of the measure (provided support and received support); those factors predicted current and future couple satisfaction. QSC scales also showed good internal consistency as well as good test–retest reliability after a 1-year period. These findings reveal satisfactory psychometric properties and justify the QSC's use in clinical settings and research protocols. Strengths, limitations, and recommendations for futures research are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)