A Quantum Adiabatic Evolution Algorithm Applied to Random Instances of an NP-Complete Problem

A quantum system will stay near its instantaneous ground state if the Hamiltonian that governs its evolution varies slowly enough. This quantum adiabatic behavior is the basis of a new class of algorithms for quantum computing. We test one such algorithm by applying it to randomly generated, hard, instances of an NP-complete problem. For the small examples that we can simulate, the quantum adiabatic algorithm works well, and provides evidence that quantum computers (if large ones can be built) may be able to outperform ordinary computers on hard sets of instances of NP-complete problems.Comment: 15 pages, 6 figures, email correspondence to [email protected] ; a shorter version of this article appeared in the April 20, 2001 issue of Science; see http://www.sciencemag.org/cgi/content/full/292/5516/47

A STOCHASTIC MODELING FOR THE UNSTABLE FINANCIAL MARKETS

Considering the present economic context, the measurement of performances has become a permanent preoccupation for organizations, since the whole process is based on it, offering the necessary feedback to identify both the positive actions which have led to favorable results for the organization, and the negative ones, in order to correct them in the future. To do this, we have to measure what is most importantly to measure. Starting from these considerations, the present paper approaches from a theoretical and practical point of view the economic rate of return as the indicator which synthesizes best an organization’s financial-economic performance. We have calculated and analyzed the economic rate of return for a group of Ten Romanian Firms in the food industry, through different calculation relations, pointing out the advantages/disadvantages of each calculation method.belated integral, forward-backward stochastic equations, pathwise uniqueness, financial modeling.

The Paths to Choreography Extraction

Choreographies are global descriptions of interactions among concurrent components, most notably used in the settings of verification (e.g., Multiparty Session Types) and synthesis of correct-by-construction software (Choreographic Programming). They require a top-down approach: programmers first write choreographies, and then use them to verify or synthesize their programs. However, most existing software does not come with choreographies yet, which prevents their application. To attack this problem, we propose a novel methodology (called choreography extraction) that, given a set of programs or protocol specifications, automatically constructs a choreography that describes their behavior. The key to our extraction is identifying a set of paths in a graph that represents the symbolic execution of the programs of interest. Our method improves on previous work in several directions: we can now deal with programs that are equipped with a state and internal computation capabilities; time complexity is dramatically better; we capture programs that are correct but not necessarily synchronizable, i.e., they work because they exploit asynchronous communication

Endothelialization of a New Dacron Graft in an Experimental Model: Light Microscopy, Electron Microscopy and Immunocytochemistry

Two types of synthetic vascular grafts, Dacron Triaxial and Dacron Gelseal Triaxial, were implanted into both the common carotids of sheep. The animals were sacrificed 1, 2, 8, and 16 weeks after surgery. Multiple specimens, obtained from grafts and anastomoses, were studied by light microscopy, transmission and scanning electron microscopy. A parallel immunocytochemical analysis was performed on some specimens. Dacron Triaxial grafts failed to develop a complete neointimal coverage. Myofibroblasts and fibroblasts were the dominant cells in such synthetic graft. Moreover, focal areas of stripping, platelet deposition, and thrombosis were observed at 8 and 16 weeks. In contrast, a stable endothelial coverage developed on the Gelseal Triaxial grafts after 16 weeks

Healing of Prosthetic Arterial Grafts

Numerous synthetic biomaterials have been developed as vascular substitutes. In vitro, ex vivo and in vivo studies have demonstrated that in animals, selected materials, i.e., Dacron and ePTFE (expanded polytetrafluoroethylene) grafts, are successfully incorporated in both the large and the small caliber host arteries through a process which is generally referred to as graft healing. Morphologically, this process consists of a series of complex events including fibrin deposition and degradation, monocyte-macrophage recruitment and flow-oriented cell-layer generation, this last event being the complete endothelialization of the arterial substitute. In contrast to experimental animals, the flow surface of synthetic vascular grafts remains unhealed in humans, particularly in the small caliber conduits. Healing in man consists of graft incorporation by the perigraft fibrous tissue response with a surface covered by more or less compacted, cross-linked fibrin. It is therefore obvious that: i) marked differences in graft healing exist between animals and man; and ii) the usual mechanisms of graft endothelialization are partially ineffective in man. In order to guarantee the patency of synthetic vascular grafts for human small artery bypass, new strategies and approaches have recently been attempted. In particular, the endothelial cell seeding approach has been successfully accomplished in animals and is being experimented in human clinical studies. The problems and results of this biological approach are outlined in this paper

Evaluación del desplazamiento del sobreengrasante en jabones blandos

The metathesis that occurs in soaps superfatted with fatty acids is studied, verified and evaluated. The analysis deals with soaps in solution (shaving creams), in which the problem is showed clearly due to the hydrolysis of the soap. The study is concern on the main fatty acids of the analyzed samples. Knowing the fatty acids distribution, the expected theoretical concentrations of the fatty acids were estimated and were compared with those found by Gas Chromatography.Se estudia, comprueba y cuantifica el fenómeno de la metátesis que ocurre en jabones reengrasados con ácidos grasos. El análisis se refiere a jabones en disolución (cremas de afeitar) en los cuales el problema es más patente debido a fenómenos de hidrólisis. El estudio se centra en los ácidos grasos mayoritarios de las muestras analizadas. Conociendo la distribución de los ácidos grasos se estimaron las concentraciones que teóricamente debían ser encontradas y fueron comparadas con las concentraciones halladas por cromatografía en fase gaseosa

Determinación cuantitativa de bactericidas en cosméticos "dermoprotectores"

A rapid, easy and reproducible method is described for the quantitative determination of the usual antimicrobial preservatives used in the cosmetic industry in the Spanish market with a dermoprotector claim. The method is also useful for soap bars and for surfactant solutions, in this last case the method of extraction is the only change. Gas Chromatography has been chosen as the analytical process for the set up of this method because it is a rapid and available technique, and it allows the simultaneous resolution of all the studied preservatives.Se describe un método rápido, sencillo y reproducible para la determinación cuantitativa de los bactericidas más utilizados en la industria cosmética del mercado español con fines dermoprotectores. El método es aplicable tanto a jabones sólidos como a disoluciones de tensioactivos, variando en este caso tan sólo el método de extracción. Se ha elegido la cromatografía de gases para la elaboración de este método por ser una técnica rápida y asequible, además de permitir la resolución simultánea de todos los bactericidas estudiados

Linear and Nonlinear Spectroscopy by a Common-Path Birefringent Interferometer

© 1995-2012 IEEE. We introduce a passive common-path interferometer to replace Michelson interferometers in the Fourier-Transform spectroscopy. Our device exploits birefringence to introduce a highly accurate delay between two orthogonal polarization components by continuously varying the material thickness. Due to its inherent delay stability and reproducibility, it can be used even for short wavelengths (down to ∼200 nm) without the need for any active control or position tracking. We first demonstrate its performances in linear spectroscopy, by implementing a spectrometer and a spectrophotometer. We then extend its use to nonlinear spectroscopy and, in combination with lock-in detection at MHz modulation frequencies, illustrate its application to pump-probe spectroscopy with high sensitivity (ΔT/T 500 nm) and to broadband stimulated Raman scattering microscopy in the CH stretching region

Electron Microscopy of Lipid Deposits in Human Atherosclerosis

The filipin probe associated with tannic acid stain was used to study intra-and extracellular lipids in surgically removed human atherosclerotic lesions (n = 20). In particular, intimal thickenings, fatty streaks and fibrolipidic plaques have been investigated by using mainly transmission and scanning electron microscopy. In the intimal thickenings, the lipid deposits were mainly localized in the subendothelial space as homogeneously sized particles (40-140 nm) and more heterogeneous uni-multilamellar vesicles (35-700 nm). Intermediate lipid forms were also observed. In the fatty streaks, the lipid deposits were intracellular and mainly observed in cells with a monocyte/macrophagic phenotype. Lipid inclusions, lipid lysosomal bodies and intracellular cholesterol crystals very similar to those observed in experimentally induced atherosclerosis were documented. In the fibrolipidic plaque the lipid deposits were found both in the intracellular and in the extracellular compartments. Lipids accumulated within arterial macrophages and smooth muscle cells, usually as lipid droplets. Clusters of lipoprotein-like particles (50 nm in diameter) as well as larger uni-multilamellar lipids (700 nm) with an occasional compound appearance were particularly observed bound to elastic tissue and collagen fibers. These morphological observations outline the complexity of lipid metabolism in the various histological aspects of human atherosclerosis