A Lorentzian Quantum Geometry

We propose a formulation of a Lorentzian quantum geometry based on the framework of causal fermion systems. After giving the general definition of causal fermion systems, we deduce space-time as a topological space with an underlying causal structure. Restricting attention to systems of spin dimension two, we derive the objects of our quantum geometry: the spin space, the tangent space endowed with a Lorentzian metric, connection and curvature. In order to get the correspondence to differential geometry, we construct examples of causal fermion systems by regularizing Dirac sea configurations in Minkowski space and on a globally hyperbolic Lorentzian manifold. When removing the regularization, the objects of our quantum geometry reduce precisely to the common objects of Lorentzian spin geometry, up to higher order curvature corrections.Comment: 65 pages, LaTeX, 4 figures, many small improvements (published version

Leisure-related mobility of elderly people: ways to sustainability

Owing to grown life expectancy as well as increasing financial scope, car ownership and possession of driving licences, the elderly of today have numerous opportunities regarding their leisure activities. Serious health problems and social constraints are generally infrequent before the age of about 80. Thus, the first 10-20 years of retirement are characterized by good health and the absence of occupational and/or family commitments, allowing for an active leisure life. Leisure-related mobility among the elderly relies increasingly on private vehicles. Car use is the basis for a wider activity space, including locations that are far away and/or badly accessible by means of public transport. The resulting increase in motorized leisure-related traffic has negative ecological impacts. Thus, the question arises of how the elder population's leisure mobility can take place in a more sustainable manner. Within the FRAME project, 4,500 people aged 60+ were interviewed regarding their leisure activities. The empirical results give detailed information about determinants of and motives for leisure-related mobility. While leisure activities are largely determined by individual factors like health or car availability, other factors like settlement patterns and local leisure infrastructure also have significant influence. Therefore samples were taken from urban, suburban and rural areas. The FRAME household survey shows in how far elderly people from diverse sample areas differ with regard to their leisure activities, means of transport and distances travelled. To start with, the results show differences between sample groups from urban, suburban and rural areas. In addition, there are also variations within these three spatial categories. The paper intends to illustrate to what extent leisure-related mobility of the elderly is influenced by diverse spatial structures as well as the personal situation. We will discuss how individual residential settings affect leisure activities. Moreover, we will investigate the relation between infrastructure (local offers in leisure activities, transportation, etc.) and participation in local leisure activities and the selection of distant localities respectively. The results show, not surprisingly, large variations due to diverse equipments with leisure facilities. Interestingly, we also found substantial qualitative differences between urban, suburban and rural facilities resulting in distinct spatial orientation patterns. The results illustrating the relationship between spatial context and leisure-related traffic are used to evaluate which settlement structure is favourable to sustainable leisure mobility. We will identify local settings minimising leisure-related traffic and thus pollution. This aspect bears particular importance as the recreational wants of the growing number of elderly people have to be supplied. Attempting to mediate ecological and social demands, the paper aims to identify a set of conditions for the location and design of leisure facilities. These should promote sustainable mobility.

Entry-rates, the share of surviving businesses and employment growth: differences between West and East Germany since unification

Entry-Rates, survival-rates and growth-rates vary considerably between regions. The aim of our paper is firstly to point out these differences in Germany as a whole. It will be shown how these three parameters work together. Are there regions in which all three are favourable for newly founded firms? Sternberg (2000) states that it is to be expected that in regions with high rates of entry the survival-rates should be high, too. This is because a convenient environment for the founding of new firms should be equally favourable for the further development of these firms. With a database that covers all newly founded establishments since 1983 (West-Germany) resp. 1992 (East-Germany), cohorts of each year can be analysed until the year 2000. In a second step we will analyse east - west differences since the unification. Newly founded firms are of outstanding importance for the development of the market economy in eastern Germany. The transition of the economic system came as a shock to existing firms and led to an enormous boom in the establishment of new firms. Brixy & Kohaut (1999) showed that shortly after unification a kind of 'start-window' existed during which the conditions for establishment, growth and survival of new firms were extraordinarily good. Now 12 years after the unification it can be shown, that founding-rates, growth-rates and survival-rates in both parts of Germany came into line. But there are sizeable regional differences in both parts. A in-depths comparison gives the possibility to compare the performance of special types of business over time and space in different cohorts. This should lead to a better understanding of the regional problems faced by regional economies.

Active Vision for Scene Understanding

Visual perception is one of the most important sources of information for both humans and robots. A particular challenge is the acquisition and interpretation of complex unstructured scenes. This work contributes to active vision for humanoid robots. A semantic model of the scene is created, which is extended by successively changing the robot\u27s view in order to explore interaction possibilities of the scene

Weak Interaction Rates Of sd-Shell Nuclei In Stellar Environment Calculated in the Proton-Neutron Quasiparticle Random Phase Approximation

Allowed weak interaction rates for sd-shell nuclei in stellar environment are calculated using a generalized form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. Twelve different weak rates are calculated for each nucleus as a function of temperature and density. This project consists of calculation of weak rates for a total of 709 nuclei with masses ranging from A = 18 to 100. This paper contains calculated weak rates for sd-shell nuclei. The calculated capture and decay rates take into consideration the latest experimental energy levels and ft value compilations. The results are also compared with earlier works. Particle emission processes from excited states, previously ignored, are taken into account, and are found to significantly affect some beta decay rates.Comment: 64 pages, 17 figures, rate tables are presented in an abbreviated form to save space. Complete rate tables can be seen in the original pape

Regional patterns and determinants of new firm formation and survival in western Germany

"There is a large body of literature on the determinants of regional variation in new firm formation. In contrast there are few articles on the spatial differences in new firm survival. Using panel data we analyse both items for 74 western German regions over a ten-year period. The positive relationship between entry and exit which is often stated suggests a negative correlation between entry and survival. On the other hand, however, it seems convincing that regions with high birth rates should also have high survival rates, because a favourable environment for the founding of new firms should also be encouraging for the development of these firms. However, an analysis of both rates for 74 western German regions over a ten-year period reveals the existence of a negative relationship in general. This means that the survival rates are below average in regions with high birth rates. Despite this overall correlation, however, it is shown that the spatial pattern of a combination of both rates is complex, and all types of possible relationships exist. With a multivariate panel analysis we study the factors that influence regional birth and survival rates using the same set of independent variables. It is shown that in the service sector most variables literally work in opposite directions in the birth and survival rates models. But this does not hold for the manufacturing sector. This can be rated as evidence for the 'supportive environment thesis'. The reason for this is a completely different outcome of the estimated birth rates models for both industry sectors, whereas there are only minor differences in the estimated survival rate models. We can therefore deduce firstly that the two industries have different requirements for their 'seed bed' but not for their further successful development; and secondly, that the spatial structures which increase the number of newly founded businesses in the service sector are detrimental to the survival rates of newly founded firms." (author's abstract

Active Vision for Scene Understanding

Visual perception is one of the most important sources of information for both humans and robots. A particular challenge is the acquisition and interpretation of complex unstructured scenes. This work contributes to active vision for humanoid robots. A semantic model of the scene is created, which is extended by successively changing the robot's view in order to explore interaction possibilities of the scene

The Causal Perturbation Expansion Revisited: Rescaling the Interacting Dirac Sea

The causal perturbation expansion defines the Dirac sea in the presence of a time-dependent external field. It yields an operator whose image generalizes the vacuum solutions of negative energy and thus gives a canonical splitting of the solution space into two subspaces. After giving a self-contained introduction to the ideas and techniques, we show that this operator is in general not idempotent. We modify the standard construction by a rescaling procedure giving a projector on the generalized negative-energy subspace. The resulting rescaled causal perturbation expansion uniquely defines the fermionic projector in terms of a series of distributional solutions of the Dirac equation. The technical core of the paper is to work out the combinatorics of the expansion in detail. It is also shown that the fermionic projector with interaction can be obtained from the free projector by a unitary transformation. We finally analyze the consequences of the rescaling procedure on the light-cone expansion.Comment: 34 pages, LaTeX, introduction expande

Implementation Of Electronic Medical Records: How Healthcare Providers Are Managing The Challenges Of Going Digital

Electronic medical records (EMRs) are the newest form of documenting a patient’s medical record.  An EMR is a system that contains a patient’s personal medical history, test results, dictations, and other medical and financial information.  EMRs will improve healthcare by enhancing patient care, preventative health, and provider convenience and is an extreme improvement to an already highly technological healthcare corporation.  The implementation ‘wave’ is not happening just because it is an improvement to healthcare, but it is also moving forward because it is required by the U.S. government.  President Obama recently employed a stimulus package that will assist healthcare establishments with startup of electronic medical records.  Along with the great improvements and advantages come inconveniences, challenges, and high costs.  For large hospitals, EMR deployments can cost the organization millions of dollars; hospitals can spend from $25,000 to$60,000 per physician to deploy a system.  EMR deployment is a public policy challenge with the federal government possibly spending more than $20 billion in stimulus funds to reimburse providers for EMR implementations.  EMR system implementations are like any business process reengineering project because they cause many challenges.  Employees are not always accepting of change and managing change effectively is critical to successful implementation of any new technology.  Additionally, new electronic technologies increase privacy issues while at the same time healthcare facilities are becoming stricter with confidentiality.  Electronic medical record implementation is complex, but the benefits of organization and improved healthcare outweigh the minor setbacks.  In this study, data was gathered from two healthcare facilities through interviews of the leaders of the EMR implementation process at each facility.  Trade journals and EMR vendor information was also explored.  The goal was to explore the phenomenon of the EMR implementation in this short term research project