Polynomial-Time, Semantically-Secure Encryption Achieving the Secrecy Capacity

In the wiretap channel setting, one aims to get information-theoretic privacy of communicated data based only on the assumption that the channel from sender to receiver is noisier than the one from sender to adversary. The secrecy capacity is the optimal (highest possible) rate of a secure scheme, and the existence of schemes achieving it has been shown. For thirty years the ultimate and unreached goal has been to achieve this optimal rate with a scheme that is polynomial-time. (This means both encryption and decryption are proven polynomial time algorithms.) This paper finally delivers such a scheme. In fact it does more. Our scheme not only meets the classical notion of security from the wiretap literature, called MIS-R (mutual information security for random messages) but achieves the strictly stronger notion of semantic security, thus delivering more in terms of security without loss of rate

Some aspects of medical care in the USSR

As a participant in the World Health Organization Seminar on Medical Care, which was held earlier this year in the Soviet Union, I had the opportunity of observing certain characteristic features of the Soviet system of medical care which, in some respects, render it quite unique. It is the purpose of this article to describe some of these features. First priority was given to the provision of elementary forms of first aid in those areas where medical services were non-existent and, concomitantly, to instruct the people in the rudiments of hygiene and health care. The next step was the setting up of small cottage-type hospitals which were sited so as to be within reasonable distance from a number of first aid points. Major operations were carried out however in Rayon hospitals, which were purposely established to cater for a wide range of facilities. The urban woman also has a domiciliary medical care service, and facilities are also being provided for adolescents to see specialists at polyclinics with whom they can discuss their problems and who give them advice. The desire to provide a medical service by highly qualified workers has developed almost into an obsession for specialization. It is practically true to say that Soviet Medical Schools do not produce "doctors" but "specialists". Moreover, the term prevention is taken in the widest possible sense. It is not taken to signify simply the prevention of disease but also the prevention of the exacerbation of pathological conditions already existing. Although the medical service is not completely free, of significant importance is the extraordinary role of health volunteers.peer-reviewe

Effects of Effective Dendrite Size on Dynamic Tensile Properties of Ti-Based Amorphous Matrix Composites

In this study, dynamic tensile properties of dendrite-containing Ti-based amorphous matrix composites were examined, and effects of dendrite size on dynamic deformation were investigated. The composites contained 73 to 76 vol pct of dendrites whose effective sizes were varied from 63 to 103 mu m. The dynamic tensile test results indicated that the ultimate tensile strength increased up to 1.25 GPa, whereas the elongation decreased to 1 pct, although the overall strength and elongation trends followed those of the quasi-static tensile test. According to the observation of dynamic tensile deformation behavior, very few deformation bands were observed beneath the fracture surface in the composite containing large dendrites. In the composite containing small dendrites, deformation bands initiated inside small dendrites propagated into adjacent dendrites through the amorphous matrix, and were crossly intersect perpendicularly in widely deformed areas, which beneficially worked for elongation as well as strength.open1131sciescopu

Dreijen Regeneration Study: Professional Academy 2007

This year the students of the “Professional Academy”, a combined theory and design class in landscape architecture, elaborated on a vision on the campus “de Dreijen” in Wageningen. This campus will be left by the university within the coming decade, university functions mainly moving towards the new campus “de Born” in the North of the city. Their “research by design” study brought about very different visions, but they all reflected the main theories learnt about urban sustainability and ecolog