Multiple input radio receiver Patent

Radio receiver with array of independently steerable antennas for deep space communicatio

Apparatus for aiding a pilot in avoiding a midair collision between aircraft

An apparatus for aiding a pilot in avoiding a midair collision between aircraft is described. A protected aircraft carries a transmitter, a transponder, a receiver, and a data processor; and an intruding cooperating aircraft carries a transponder. The transmitter of the protected aircraft continuously transmits a signal to the transponders of all intruding aircraft. The transponder of each of the intruding aircraft adds the altitude of the intruding aircraft to the signal and transmits it back to the receiver of the protected aircraft. The receiver selects only the signal from the most hazardous intruding aircraft and applies it to the data processor. From this selected signal the data processor determines the closing velocity between the protected and intruding aircraft, the range between the two aircraft, their altitude difference and the time to a possible collision

Current Densities in Density Functional Theory

It is well known that any given density rho(x)can be realized by a determinantal wave function for N particles. The question addressed here is whether any given density rho(x) and current density j(x) can be simultaneously realized by a (finite kinetic energy) determinantal wave function. In case the velocity field v(x) =j(x)/rho(x) is curl free, we provide a solution for all N, and we provide an explicit upper bound for the energy. If the velocity field is not curl free, there is a finite energy solution for all N\geq 4, but we do not provide an explicit energy bound in this case. For N=2 we provide an example of a non curl free velocity field for which there is a solution, and an example for which there is no solution. The case $N=3 with a non curl free velocity field is left open.Comment: 21 pages, latex, reference adde

Perturbative test of single parameter scaling for 1D random media

Products of random matrices associated to one-dimensional random media satisfy a central limit theorem assuring convergence to a gaussian centered at the Lyapunov exponent. The hypothesis of single parameter scaling states that its variance is equal to the Lyapunov exponent. We settle discussions about its validity for a wide class of models by proving that, away from anomalies, single parameter scaling holds to lowest order perturbation theory in the disorder strength. However, it is generically violated at higher order. This is explicitely exhibited for the Anderson model.Comment: minor corrections to previous version, to appear in Annales H. Poincar

Development of Collembolans after coversion towards organic farming

In Northern Germany, a diverse and complex experimental farm of the Federal Agricultural Research Centre (FAL) was set-up in 2001 covering all main aspects of organic farming. Previously, the 600 ha farm had been managed conventionally. Adjacent conventional farms were used as reference. The aim of this project was to study collembolans, microbial biomass and soil organic carbon in six organically farmed fields managed as a crop rotation of six different crops compared with an adjacent conventionally managed field. We hypothesised that the specific management in organic farming promotes soil biota. Soil samples were taken during the growing season in 2004. Collembolan abundances and microbial biomass were lower under organic management, but, generally, collembolan diversity was higher in organically farmed fields combined with a shifting in the dominance structure of the species. This result reveals that, even after three years, the soil biota is still changing with management conversion

Contribution of organic farming to conserving and improving biodiversity in Germany avi-fauna as an example

Although it is the aim of organic farming to increase biodiversity, there is little information about the impact of organic farming on birds. From 2001 to 2003, the number of breeding birds was recorded annually on the organic experimental farm of the Institute of Organic Farming (600 ha), and on adjacent conventional and organic farms (60 ha and 40 ha) in Northern Germany. The number of skylark (Alauda arvensis) territories increased considerably after the conversion from conventional to organic farming on the premises of the Institute. Their number remained unvaried on the conventional farm. The highest density of skylark territories was found on the farm which has been under organic management for many years. The number of yellowhammer (Emberiza citronella) territories fluctuated largely in relation to the availability of field margin strips, both on conventional and organic land. During the breeding season aerial hunters (swallows and swifts) and raptors significantly preferred organic fields. Outside the breeding season, densities of raptors (in autumn and in winter), seed-eating birds (in autumn) and insect-eating birds (in autumn) were significantly higher on organic than on conventional fields

Ein funktionstüchtiges System privater Arbeitslosenversicherung

Es wird untersucht, wie ein System privater Versicherungen gegen das Risiko der Arbeitslosigkeit beschaffen sein sollte. Zu dem Zweck wird ein Trennsystem vorgeschlagen, das Arbeitnehmern und Arbeitgebern gleichermaßen Anreize zur Verminderung von Arbeitslosigkeit gibt. Für die Arbeitnehmer wird ein Modell zur Bestimmung des individuellen Risikos und der darauf basierenden individuellen Prämien bei alternativen Leistungen der Arbeitslosenversicherung entworfen. Für die Seite der Arbeitgeber wird vorgeschlagen, die Vorteile des amerikanischen Systems des "Experience rating" wahrzunehmen und unter Ausnutzung von Rückkopplungseffekten auszubauen. Schließlich wird auf den Regulierungsbedarf in diesem hypothetischen System privater Arbeitslosenversicherung eingegangen.The authors suggest a dual-system model of private unemployment insurance that includes incentives on the side of employees as well as of employers to reduce unemployment. Each employee pays insurance premiums according to his (her) individual risk of getting unemployed and according to his (her) preference with respect to the individual level and duration of unemployment payments. On the employers’ side the US system of experience rating is elaborated in such a way as to increase, via autoregressive processes, the built- in tendencies of unemployment reduction. In addition, the regulation necessary to operate this dual system is analysed

Die Reform der deutschen Arbeitslosenversicherung vor dem Hintergrund ihrer Geschichte

Die Rolle der deutschen Arbeitslosenversicherung wird für vier Perioden seit 1871 daraufhin analysiert, ob man bei der Suche nach einem effizienten System der Arbeitslosenversicherung aus der Geschichte lernen kann. Die vier Perioden (Periode I: 1871/1914; II: 1918/32; III: 1933/39; IV: 1949/2001) sind jeweils sehr unterschiedlicher Natur, sowohl in bezug auf die jeweils zugrunde liegende politische Situation als auch bezüglich der Höhe der Arbeitslosigkeit. Es wird gezeigt, daß die heutige Arbeitslosenversicherung in ihren Kernelementen auf das Jahr 1927 zurück-geht. Als Kernelemente werden die versicherungsferne Struktur, die Zwangsmitglied-schaft sowie das Fehlen tatsächlichen und potentiellen Wettbewerbs identifiziert. Diese Strukturen haben schon in den Krisenjahren nach 1927 nicht zur Entschärfung der Situation auf dem Arbeitsmarkt beigetragen.In search of an efficient system of unemployment insurance the authors take a look at German history. Four periods of German unemployment insurance are analyzed, namely those of 1871/1914, 1918/32, 1933/39 and 1949/2001. These periods differ greatly with respect to the levels of unemployment as well as regarding the underlying political situation. It turns out that the German unemployment insurance of today has its roots in the year 1927. The main elements - i.e. the lack of insurance principles, the mandatory character and the lack of actual or potential competition - have been upheld since then. These elements did not help ease labor market tensions in the years following 1927, similar to the revealed inefficiency of German unemployment insurance over the past 20 years

Optionen einer effizienten Gestaltung der Arbeitslosenversicherung

The paper is about the economically efficient design of financial transfers to the unemployed in a highly industrialized country. There have been quite a few contributions to this problem — for example by Beenstock/Brasse, Feldstein/ Altman, Grubel, Orzag/Snower — which are presented and discussed. It turns out that a true unemployment insurance would be the most efficient way to solve the transfer problem. The second part of the paper deals with often-raised objections against such a solution. For example, insurability is often denied on the ground that an unemployment insurance would be too expensive due to moral hazard and adverse selection. It is shown that neither moral hazard nor adverse selection are insurmountable obstacles to a private insurance market.Die internationale Diskussion der letzten Jahrzehnte hat zur Frage nach einer effizienten Gestaltung der Einkommenssicherung von Arbeitslosen eine Reihe von Vorschlägen hervorgebracht, wie die von Beenstock/Brasse, Feldstein /Altman, Grubel und Orzag/Snower. Sie werden dargestellt und bewertet. Als ökonomisch beste Lösung stellt sich ein reines Versicherungsmodell heraus. Im zweiten Teil der Arbeit wird daher auf die besonders in Deutschland vorherrschenden Zweifel an der Versicherbarkeit des Arbeitslosigkeitsrisikos eingegangen; diese Zweifel sind zum Teil auch Gegenstand der Standardwerke zur Versicherungsökonomie. Es wird gezeigt, daß die Kerneinwände nicht tragfähig sind: "Moral hazard" und "Adverse selection" schließen die Versicherbarkeit des Arbeitslosigkeitsrisikos keineswegs aus

Alternative Systeme der Arbeitslosenversicherung: das Beispiel der Vereinigten Staaten und des Vereinigten Königreichs

Comparing the unemployment insurance systems of the United States and of the United Kingdom it is shown that the US unemployment insurance (UI) is the only system that provides for a negative feedback between UI expenditures and layoffs (“experience rating”). The UK has no specific UI: Unemployment benefits are paid by the “National Insurance” which also covers other elements of social security, such as health care and retirement payments. Focussing therefore on the US literature it turns out that a major part deals with the demand side of the labour market, whereas the German literature rather concentrates on the supply side.Im Rahmen eines Vergleichs der amerikanischen und britischen Systeme der Arbeitslosenversicherung wird gezeigt, daß das amerikanische System, auch anders als das deutsche, eine negative Rückkopplung zwischen den Ausgaben für die Arbeitslosenversicherung und der Höhe der Freisetzung von Arbeitskräften aufweist ("experience rating"). Im Vereinigten Königreich gibt es keine Arbeitslosenversicherung im herkömmlichen Sinne: Die Einkommenssicherung bei Arbeitslosigkeit erfolgt durch die "National Insurance", die das gesamte System der sozialen Sicherung (einschließlich Gesundheitswesen und Alterssicherung) abdeckt. Als bemerkenswert wird herausgestellt, daß anders als etwa die vergleichbaren Analysen der deutschen Arbeitslosenversicherung - die sich vorwiegend mit der Angebotsseite des Arbeitsmarktes befassen - die amerikanische Literatur zu einem großen Teil an der Nachfrage nach Arbeit ansetzt