Optimized implementation of the Lanczos method for magnetic systems

Numerically exact investigations of interacting spin systems provide a major tool for an understanding of their magnetic properties. For medium size systems the approximate Lanczos diagonalization is the most common method. In this article we suggest two improvements: efficient basis coding in subspaces and simple restructuring for openMP parallelization.Comment: 9 pages, 2 figues, submitted to Journal of Computational Physic

Scattering by fluffy grains

There are indications (Greenberg et al., 1988), that fluffy (i.e., porous) particles are responsible for the observed 3.4 and 10 micron emissions of comet Halley. The absorption characteristics of small particles both solid and fluffy are needed in order to explain the Halley emissions. How isolated small solid particles react to an external radiation field is well known - the Rayleigh approximation. How these same small particles emit when assembled as fluffy aggregates in another question. To what degree are the emission spectra of isolated and aggregated particles comparable. In order to quantify the assertion that fluffy particles produce the observed Halley infrared emission features, the authors are performing calculations to determine the effect of porosity on the absorption characteristics of aggregates of interstellar grain-type particles. The calculations are based on an integral representation of the scattered electromagnetic field. Results are given with application to comet Halley

Experimental demonstration of continuous variable purification of squeezed states

We report on the first experimental demonstration of purification of nonclassical continuous variable states. The protocol uses two copies of phase-diffused states overlapped on a beam splitter and provides Gaussified, less mixed states with the degree of squeezing improved. The protocol uses only linear optical devices such as beam splitters and homodyne detection, thereby proving these optical elements can be used for successful purification of this type of state decoherence which occurs in optical transmission channels

A comparative study of the continuum and emission characteristics of comet dust. 1: Are the silicates in Comet Halley and Kohoutek amorphous or crystalline

A continuum emission was subtracted from the 10 micron emission observed towards comets Halley and Kohoutek. The 10 micron excess emissions were compared with BN absorption and laboratory amorphous silicates. The results show that cometary silicates are predominantly amorphous which is consistent with the interstellar dust model of comets. It is concluded that cometary silicates are predominantly similar to interstellar silicates. For a periodic comet like Comet Halley, it is to be expected that some of the silicate may have been heated enough to convert to crystalline form. But apparently, this is only a small fraction of the total. A comparison of Comet Halley silicates with a combination of the crystalline forms observed in interplanetary dust particles (IPDs) seemed reasonable at first sight (Walker 1988, Brownlee 1988). But, if true, it would imply that the total silicate mass in Comet Halley dust is lower than that given by mass spectrometry data of Kissel and Krueger (1987). They estimated m sub org/m sub sil = 0.5 while using crystalline silicate to produce the 10 micron emission would give m sub org/m sub sil = 5 (Greenberg et al. 1988). This is a factor of 10 too high

Observatoires du développement, observatoires pour le développement

L'arbitrage entre le coût et la richesse des données qu'un observatoire collecte nécessite des critères méthodologiques. Ces critères, qui sont nés de la réflexion sur une comparaison de l'évolution sociale des quatre principaux pays d'Europe de l'Ouest au cours d'un siècle (1860-1960), sont encore plus pertinents si on s'intéresse à la notion d'observatoire dans les pays du Sud. En premier lieu, l'arbitrage concerne le choix entre le nombre des unités d'observation retenues et l'ampleur de l'horizon temporel sur lequel portent ces observations. Plus nombreuses sont ces unités, moins on peut adopter un horizon temporel suffisamment large. Il faut donc réfléchir aux gains et aux coûts qui en résultent. En deuxième lieu, indépendamment du nombre d'unités d'observation, leur profil respectif doit être choisi en fonction de critères théoriques explicites. En troisième lieu, se pose le problème de la relation entre l'horizon temporel des mesures et la fréquence de ces dernières. Là encore, l'arbitrage ne peut être satisfaisant que si on dispose préalablement d'une théorie sur l'intensité relative du changement qu'on veut identifier. Par ailleurs, si ces arbitrages sont nécessairement liés à des problèmes de coûts, ils doivent aussi être opérés en termes de la qualité des données recueillies. Enfin, la validité des arbitrages exercés dépend de l'efficacité avec laquelle les chercheurs savent dépasser les frontières disciplinaires et paradigmatiques. (Résumé d'auteur

Preparing the bound instance of quantum entanglement

Among the possibly most intriguing aspects of quantum entanglement is that it comes in "free" and "bound" instances. Bound entangled states require entangled states in preparation but, once realized, no free entanglement and therefore no pure maximally entangled pairs can be regained. Their existence hence certifies an intrinsic irreversibility of entanglement in nature and suggests a connection with thermodynamics. In this work, we present a first experimental unconditional preparation and detection of a bound entangled state of light. We consider continuous-variable entanglement, use convex optimization to identify regimes rendering its bound character well certifiable, and realize an experiment that continuously produced a distributed bound entangled state with an extraordinary and unprecedented significance of more than ten standard deviations away from both separability and distillability. Our results show that the approach chosen allows for the efficient and precise preparation of multimode entangled states of light with various applications in quantum information, quantum state engineering and high precision metrology.Comment: The final version accounts for a recent comment in Nature Physics [24] clarifying that a previous claim of having generated bound entanglement [23] was not supported by the authors' data. We also extended our introduction and discussion and also added reference

Внешнеэкономическая деятельность в системе оценки инвестиционного рейтинга отраслевых предприятий Украины

In this paper we describe a variation of monotone frameworks that enables us to perform approximate typing of Python, in particular for dealing with some of its more dynamic features such as first-class functions and Python’s dynamic class system. We additionally introduce a substantial number of variants of the basic analysis in order to experimentally discover which configurations attain the best balance of cost and precision. For example, the analysis allows us to be selectively flow-insensitive for certain classes of identifiers, and the amount of call-site context is configurable. Results of our evaluation include that adding call-site sensitivity and parameterized types has little effect on precision; in terms of speed call-site sensitivity is very costly. On the other hand, flow-insensitive treatment of module scope identifiers has a strongly positive effect, often both in terms of precision and speed

Investment in Human Capital of a Powerful Interest Group: The Case of the Medical Profession in Britain, France, Sweden and the United States from 1890 to 1970

This paper presents a new agenda for analyzing the consequences from investments in human capital by suggesting that sociological research should focus on particular sectors of society, that performances other than economic growth and productivity should be considered, and that the role of the state influences the impact which investments in human capital have on system performance. The research assesses the impact which investments in doctors and medical specialists have on social effectiveness (measured as reductions in mortality) and social efficiency (the level of health achieved relative to the cost per capita) in Britain, France, Sweden and the United States during the period between 1890 and 1970. In addition to evaluating the impact of investments in human capital on social efficiency and social effectiveness, the paper contributes to the literature on the state by developing measures for assessing the contribution of state structure on system performance. As hypothesized, investments in human capital are socially effective but not socially efficient. When the state intervenes in the delivery of medical care, it has a multiplier effect on the impact of human capital on social effectiveness.Dieses Papier stellt einen neuen Anlauf zur Analyse der Konsequenzen von Investitionen in Humankapital dar, indem es vorschlägt, sich in der Forschung auf spezifische Gesellschaftsbereiche zu konzentrieren, daß Leistungsmaße jenseits ökonomischen Wachstums und ökonomischer Produktivität Berücksichtigung finden. Auch der intervenierende Einfluß des Staates auf die Wirkungen, welche Investitionen in Humankapital auf die Leistungsfähigkeiten des Systems haben, sollte berücksichtigt werden. Die in diesem Aufsatz dargestellte Forschung schätzt die Wirkungen ab, welche Investitionen in Ärzte und medizinische Spezialisten auf die soziale Effektivität (gemessen als Verminderung von Sterblichkeit) und soziale Effizienz (das Gesundheitsniveau im Verhältnis zu den Gesundheitskosten per Einwohner) in Großbritannien, Frankreich, Schweden und den Vereinigten Staaten während des Zeitraums von 1890 bis 1970 hatten. Über diese Evaluation hinaus ist der Aufsatz ein Beitrag zur staatstheoretischen Literatur, indem er Maße entwickelt, mit denen die Wirkung staatlicher Strukturen auf die Leistungsfähigkeit spezifischer Systeme abgeschätzt werden können. Investitionen in Humankapital erweisen sich als sozial effektiv aber nicht effizient. Immer dann, wenn der Staat in das System medizinischer Dienstleistungen eingreift, hat dies einen Multiplikationseffekt hinsichtlich des Einflusses von Humankapital auf soziale Effektivität.1. Introduction 2. Theoretical Framework 2.1 Human Capital and Social Effectiveness 2.2 Human Capital and Social Efficiency 2.3 Physicians-, the State, and Social Performances 3. Research Design, Data, and Methodology 3.1 The Dependent Variables: Social Effectiveness and Social Efficiency 3.2 The Independent Variables 3.3 Data 3.4 Data Analytic Techniques 4. Findings 4.1 Trends in Mortality and Social Efficiency 4.2 Human Capital Investment and Social Effectiveness 4.3 Human Capital Investment and Social Efficiency 5. Discussion Appendix: Data Sources Bibliograph

Professional-Bureaucratic Conflict and Intraorganizational Powerlessness among Social Workers

Since Max Weber\u27s classic writings on bureaucracy, the relationship between professionalization and bureaucracy has been a central focus of organization theory and research (e.g., Parsons, 1947; Goulduer, 1954; Blauner, 1964; Blau, 1968, Meyer, 1968b; Blau and Schoenherr, 1971). Some research suggests that professionalization and bureaucratization are alternative or conflicting modes of organization (Udy, 1959 ; Stinchecombe, 1959; Litwak, 1961; Burns and Stalker, 1961; Thompson, 1961; Hall, 1963; Rage, 1965). While other research suggests that professionalization and bureaucratization are actually congruent because structural accommdation minimizes dissension between professionals and bureaucrats (e.g., Blau, 1968; Meyer, 1968b; Kirsch and Lengermann, 1972). However, the resolution of professional bureaucratic discord does not always occur and may vary depending on the status or legitimation of the profession. In the case of an emerging profession or semi-profession, like social work (Scott, 1969; Toren, 1969), this conflict may remain unresolved and produce alienation and work dissatisfaction. This research investigates the impact of bureaucratic constraint and professionalism on one aspect of alienation among social workers: powerlessness, or disaffection regarding one\u27s participation in organizational decision-making. This research treats powerlessness as an organizationally - specific phenomenon. With some exceptions (e.g., Blauner, 1964; Clark, 1959; Lefton, et.al., 1959; Segal, 1969), powerlessness has been dealt with in a societal context (Lystad, 1972). In most research, powerlessness (or any form of alienation) has been viewed as a generalized manifestation of person-toworld or person-to-society relations. Intraorganizational powerlessness has been of interest primarily because of its alleged ramifications beyond the organizational context in which it is generated. Seeman (1967) found little support for this generalization hypothesis , and suggests that this is due to persons\u27 propensity to segmentalize different spheres of life. In this vein, the present research treats powerlessness as an organizationallyspecific phenomenon, not as a diffuse aspect of a person\u27s relation to his social world