833 research outputs found
Cosmic acceleration from M theory on twisted spaces
No full textdoi: 10.1103/PhysRevD.72.083509In a recent paper [I. P. Neupane and D. L. Wiltshire, Phys. Lett. B 619, 201 (2005).] we have found a new class of accelerating cosmologies arising from a time-dependent compactification of classical supergravity on product spaces that include one or more geometric twists along with nontrivial curved internal spaces. With such effects, a scalar potential can have a local minimum with positive vacuum energy. The existence of such a minimum generically predicts a period of accelerated expansion in the four-dimensional Einstein conformal frame. Here we extend our knowledge of these cosmological solutions by presenting new examples and discuss the properties of the solutions in a more general setting. We also relate the known (asymptotic) solutions for multiscalar fields with exponential potentials to the accelerating solutions arising from simple (or twisted) product spaces for internal manifolds
I.P. skvortzov and imperial Kazan university
No full text© 2019, Ecozone, OAIMDD. All rights reserved. Irinarkh Polikhronievich Skvortzov was a famous Russian scientist. He was born on 5 August, 1847. I.P. Skvortzov graduated from Imperial Kazan University with MD degree. All his life was connected with medical and educational activities. Scientific interests mainly concerned hygiene and microbiology. He was the author of some original microbiological hypothesis. I.P. Skvortzov made a great input to Russian and international science in the end of XIX century. This historical review opens for the first time I.P. Skvortzov for Western readers
Notes on meteorological balloon mission planning
No full textIn the 21st century the high altitude gas balloon remains an indispensable tool in atmospheric science, meteorology and other applications requiring stratospheric observations. A prerequisite of the effectiveness of many types of balloon operations is an accurate trajectory forecasting capability, complete with appropriate error estimates. This is particularly important in targeted flights, sample return missions or flights of expensive instruments, whose recovery is essential. The ASTRA (Atmospheric Science Through Robotic Aircraft) initiative led to the development of such a forecast model, which is at the centre of the present paper. A key source of error in such models is our incomplete understanding of the drag opposing the rise of balloons in the free atmosphere – here we propose a new, stochastic model based on empirical data derived from thousands of radiosonde flights. We also examine other sources of prediction error affecting the accuracy of the flight path forecast, such as uncertainties in the wind profile and balloon envelope manufacturing variability. A Monte Carlo framework is used to provide probabilistic touchdown point estimates taking these error sources into account. The above elements have been integrated into a web service, which can be used as a flight planning tool – here we review the key features of its architecture
Accelerating cosmologies from compactification with a twist
No full textDOI: 10.1016/j.physletb.2005.06.008It is demonstrated by explicit solutions of the 4+n–dimensional vacuum Einstein equations that
accelerating cosmologies in the Einstein conformal frame can be obtained by a time–dependent compactification
of string/M–theory, even in the case that internal dimensions are Ricci–flat, provided
one includes one or more geometric twists. Such acceleration is transient. When both compact
hyperbolic internal spaces and geometric twists are included, however, the period of accelerated
expansion may be made arbitrarily large
Accelerating cosmologies from compactification with a twist
No full textDOI: 10.1016/j.physletb.2005.06.008It is demonstrated by explicit solutions of the 4+n–dimensional vacuum Einstein equations that
accelerating cosmologies in the Einstein conformal frame can be obtained by a time–dependent compactification
of string/M–theory, even in the case that internal dimensions are Ricci–flat, provided
one includes one or more geometric twists. Such acceleration is transient. When both compact
hyperbolic internal spaces and geometric twists are included, however, the period of accelerated
expansion may be made arbitrarily large
Maxim Gorky and the Publishing House of I.P. Ladyzhnikov (Based on Archival Materials)
No full textBased on the hitherto unpublished archival materials, this article examines the history of creation and specific traits of an obscure small Russophone Publishing house of I.P. Ladyzhnikov. It also analyzes the role and the scope of Maxim Gorky’s contribution to the work of this publishing house. It is shown that Gorky was one of the founders of this Berlin-based firm. Not only was he an ideological inspirator of this new business, he also supported it financially. As a result of collective efforts on behalf of Gorky and prominent leaders of the Bolshevik party in 1905, the Russianlanguage publishing house was established abroad. By publishing the works of Gorky and other democratic writers of the Znanie group, it secured their copyright in Europe and America and contributed part of its income to the Bolshevik party funds. In 1905–1912, under the direction of Ladyzhnikov, all new works of Gorky were published by this press. The peak of the Publishing house of I.P. Ladyzhnikov fell upon the most fruitful creative period in the life of the main author of this publishing house — M. Gorky. At the end of 1912 Ladyzhnikov was forced to transfer his business to his partner — B.N. Rubinstein, due to financial difficulties. However, the publishing house continued to exist until 1932. The article examines in detail the lesser-studied postrevolutionary period of the Publishing house of I.P. Ladyzhnikov under the leadership of Rubinstein and demonstrates Rubinstein’s significant participation in the translation and publication of Gorky’s works, including translations and productions of his plays abroad
Design, Optimization, and Evaluation of a Path Query System
No full textThe model of the Universe of Discourse usually needs to be mapped onto the information technology environment chosen by the engineers. This mapping costs significant efforts, time and energy to construct, to use, and to maintain. All these efforts, time and energy can be saved, if the engineers choose an object data management system based on an object model powerful enough to be used to construct the model of the Universe of Discourse. The query language and the query subsystem of an object data management system based on a powerful object model must be different from other query languages and subsystems, because the underlying data model is different. The goal of this research was twofold: (1) to create a query language for such an object data management system, which encourages the formulation of semantically sound queries, supports the formulation of reusable queries, facilitates the usage of recursive queries through intuitive syntax and semantics, and (2) to verify the created query language by the design, optimization and evaluation of a query system whose primary interface is the created query language, and which enables flexible, online, user-defined consistency control of the entered data. This thesis gives an introduction to query systems, and to Perspective-DB that is an object data management system based on a powerful object model. Furthermore, this thesis gives insight into the development stages of the path query system: simple path expressions, active views, combination of path expressions, filtered path expressions, and recursive path expressions. It also describes the way the query subsystem is reused to extend the export and import facilities of the data management system. It features a functional description of the query system and of the parts of the data management system relevant to the query system, and it also handles implementation and maintenance details.Electrical Engineering, Mathematics and Computer Scienc
De doelmatigheid van de Amsterdamsche broodvoorziening
No full textMechanical, Maritime and Materials Engineerin
Theory of elementary soil-forming processes of I.P. Gerasimov and its manifestations in diverse natural zones
No full textThe theory of elementary soil-forming processes (ESP) proposed by Academician I.P. Gerasimov is discussed both in its initial version, and in its advanced perception in the beginning of XXI century. The progress and success of this theory is highlighted. The implementation of this theory is shown with real examples in various natural environments: tundra, taiga, steppe, deserts and highlands. Disputable aspects in interpreting the elementary soil-forming processes are outlined; they concern the following processes: salinization, solodization, podzolization, lessivage and some other processes. Emphasis is put on the participation of abiotic endogenous agents in the development of elementary soil-forming processes, namely, the hydrothermal metamorphism, and periglacial lithogenesis. Examples are adduced for the ESP that were revealed by the author during his research in High Arctics, Siberia, Mongolia, Chile. Proposals for the further progress of the ESP theory are outlined
Patientveiligheid: De rol van de bestuurder - Patient Safety: the role of the Board
No full textDagelijks lopen tientallen patiënten in Nederlandse ziekenhuizen iatrogeen letsel op en komen potentieel vijf mensen te overlijden als gevolg van fouten in een zorgproces dat juist als doel had hen te helpen. Nederland staat hierin niet alleen. Onderzoek in diverse Westerse landen heeft aangetoond dat 5 tot 10% van de in ziekenhuizen opgenomen patiënten onbedoelde schade oploopt. Hoewel er veel aandacht is voor het belang van patiëntveiligheid, is de snelheid waarmee verbetermaatregelen worden ingevoerd teleurstellend. In dit proefschrift wordt een antwoord gegeven op de vraag hoe een bestuurder effectief leiding kan geven aan het verbeteren van de patiëntveiligheid. Dit boek is niet alleen interessant voor bestuurders, maar voor iedereen die de patiëntveiligheid wil verbeteren en zich realiseert dat hij dat niet alleen kan.BestuurskundeTechnology, Policy and Managemen
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