On the computational security of a distributed key distribution scheme

In a distributed key distribution scheme, a set of servers helps a set of users in a group to securely obtain a common key. Security means that an adversary who corrupts some servers and some users has no information about the key of a noncorrupted group. In this work, we formalize the security analysis of one such scheme which was not considered in the original proposal. We prove the scheme is secure in the random oracle model, assuming that the Decisional Diffie-Hellman (DDH) problem is hard to solve. We also detail a possible modification of that scheme and the one in which allows us to prove the security of the schemes without assuming that a specific hash function behaves as a random oracle. As usual, this improvement in the security of the schemes is at the cost of an efficiency loss.

Contributory factors for the functional independence of oldest old

OBJECTIVE To investigate the socioeconomic and clinical factors that contribute to the functional independence of the oldest old of a community. METHOD Cross-sectional quantitative study whose sample consisted of 214 elderly people registered in Basic Health Units. Data were collected through structured interviews and application of the Functional Independence Measure. We used descriptive statistics, and for association of the variables we used the Student t-test, ANOVA and Tukey's test for multiple comparisons. RESULTS The significant variables that contributed to the functional independence were remaining economically active, practicing physical and leisure activities, having a social life, eating fruits, vegetables and meat. The orientation to conduct these practices reduces the demand for care and help needed in everyday activities. CONCLUSION Maintaining independence is primordial to delay disability and presents itself as an excellent field of work for nursing.

Launching prices for new pharmaceuticals in heavily regulated and subsidized markets

This paper provides empirical evidence on the explanatory factorsaffecting introductory prices of new pharmaceuticals in a heavilyregulated and highly subsidized market. We collect a data setconsisting of all new chemical entities launched in Spain between1997 and 2005, and model launching prices. We found that, unlike inthe US and Sweden, therapeutically "innovative" products are notoverpriced relative to "imitative" ones. Price setting is mainly used asa mechanism to adjust for inflation independently of the degree ofinnovation. The drugs that enter through the centralized EMAapproval procedure are overpriced, which may be a consequence ofmarket globalization and international price setting.

Consumer Advisory Bulletin, Beware of Scheme Targeting African Americans, January 2008

The Attorney General’s Consumer Protection Division receives hundreds of calls and consumer complaints every year. Follow these tips to avoid unexpected expense and disappointments. This record is about: Beware of Scheme Targeting African Americans

The efficiency of a carbamazepine-mianserin combination scheme in opiate detoxification.

A recent comparative randomized double-blind study has suggested the utility of a carbamazepine/mianserin combination as a treatment for opiate withdrawal. The aim of the present study was to explore the feasibility and efficiency of this combination under naturalistic conditions. Five hundred and fifty mostly polysubstance abusing patients treated with a standardized scheme combining carbamazepine and mianserin were assessed with regard to deviations to the protocol, used co-medications and retention in treatment.Three hundred and sixty three patients (66.0%) received the carbamazepine/mianserin combination as specified by the standardized protocol. In 350 patients (63.7%) the whole 10 days was completed. The most frequently used p.r.n. medications were for anxiety (47.5%) and insomnia (54.5%).The treatment of opiate withdrawal with a carbamazepine/mianserin combination scheme in an inpatient setting seems to be feasible and applicable with few adaptations to most patients, and may represent an interesting treatment option for multidrug users.

A zero-delay sequential scheme for lossy coding of individual sequences

We consider adaptive sequential lossy coding of bounded individual sequences when the performance is measured by the sequentially accumulated mean squared distortion. Theencoder and the decoder are connected via a noiseless channel of capacity $R$ and both are assumed to have zero delay. No probabilistic assumptions are made on how the sequence to be encoded is generated. For any bounded sequence of length $n$, the distortion redundancy is defined as the normalized cumulative distortion of the sequential scheme minus the normalized cumulative distortion of the best scalarquantizer of rate $R$ which is matched to this particular sequence. We demonstrate the existence of a zero-delay sequential scheme which uses common randomization in the encoder and the decoder such that the normalized maximum distortion redundancy converges to zero at a rate $n^{-1/5}\log n$ as the length of the encoded sequence $n$ increases without bound.

Optimization of the sampling scheme for maps of physical and chemical properties estimated by kriging

The sampling scheme is essential in the investigation of the spatial variability of soil properties in Soil Science studies. The high costs of sampling schemes optimized with additional sampling points for each physical and chemical soil property, prevent their use in precision agriculture. The purpose of this study was to obtain an optimal sampling scheme for physical and chemical property sets and investigate its effect on the quality of soil sampling. Soil was sampled on a 42-ha area, with 206 geo-referenced points arranged in a regular grid spaced 50 m from each other, in a depth range of 0.00-0.20 m. In order to obtain an optimal sampling scheme for every physical and chemical property, a sample grid, a medium-scale variogram and the extended Spatial Simulated Annealing (SSA) method were used to minimize kriging variance. The optimization procedure was validated by constructing maps of relative improvement comparing the sample configuration before and after the process. A greater concentration of recommended points in specific areas (NW-SE direction) was observed, which also reflects a greater estimate variance at these locations. The addition of optimal samples, for specific regions, increased the accuracy up to 2 % for chemical and 1 % for physical properties. The use of a sample grid and medium-scale variogram, as previous information for the conception of additional sampling schemes, was very promising to determine the locations of these additional points for all physical and chemical soil properties, enhancing the accuracy of kriging estimates of the physical-chemical properties.

Auguste Ott on Commercial Crises and Distributive Justice: An Early Input-Output Scheme

In 1851 the French Social economist Auguste Ott discussed the problem of gluts and commercial crises, together with the issue of distributive justice between workers in co-operative societies. He did so by means of a 'simple reproduction scheme' sharing some features with modern intersectoral transactions tables, in particular in terms of their graphical representation. This paper presents Ott's theory of crises (which was based on the disappointment of expectations) and the context of his model, and discusses its peculiarities, supplying a new piece for the reconstruction of the prehistory of input-output analysis.

Oscillations, phase-of-firing coding, and spike timing-dependent plasticity: an efficient learning scheme

Recent experiments have established that information can be encoded in the spike times of neurons relative to the phase of a background oscillation in the local field potential—a phenomenon referred to as “phase-of-firing coding” (PoFC). These firing phase preferences could result from combining an oscillation in the input current with a stimulus-dependent static component that would produce the variations in preferred phase, but it remains unclear whether these phases are an epiphenomenon or really affect neuronal interactions—only then could they have a functional role. Here we show that PoFC has a major impact on downstream learning and decoding with the now well established spike timing-dependent plasticity (STDP). To be precise, we demonstrate with simulations how a single neuron equipped with STDP robustly detects a pattern of input currents automatically encoded in the phases of a subset of its afferents, and repeating at random intervals. Remarkably, learning is possible even when only a small fraction of the afferents (~10%) exhibits PoFC. The ability of STDP to detect repeating patterns had been noted before in continuous activity, but it turns out that oscillations greatly facilitate learning. A benchmark with more conventional rate-based codes demonstrates the superiority of oscillations and PoFC for both STDP-based learning and the speed of decoding: the oscillation partially formats the input spike times, so that they mainly depend on the current input currents, and can be efficiently learned by STDP and then recognized in just one oscillation cycle. This suggests a major functional role for oscillatory brain activity that has been widely reported experimentally.

A novel semi-fragile forensic watermarking scheme for remote sensing images

Peer-reviewed