Numerical simulations studies of the convective instability onset in a supercritical fluid

Numerical simulation studies in 2D with the addition of noise are reported for the convection of a supercritical fluid,3He, in a Rayleigh-Be'nard cell where the fluid parameters and cell height L are the same as in published laboratory experiments. The noise addition is to accelerate the instability onset after starting the heat flow across the fluid, so as to bring simulations into better agreement with experimental observations. Homogeneous temperature noise and spatial lateral periodic temperature variations in the top plate were programmed into the simulations. A speed-up in the instability onset was obtained, which was most effective through the spatial temperature variations with a period of 2L, close to the wavelength of a pair of convections rolls. For a small amplitude of 0.5 microK, this perturbation gave a semiquantitative agreement with experimental observations. Results for various noise amplitudes are presented and discussed in relation to predictions by El Khouri and Carle`s.Comment: 6 pages (2-column format) 4 figures, Proceedings of NASA2004 workshop, Solvang,C

Vergleichende Eislagerung von ausgenommenen und unausgenommenen Schleien

New regulations of the German “Fisch-Hygiene-Verordnung” lay down that all fish except pelagic species have to be gutted immediately after catch or killing, especially fresh water fish from aquaculture. Only gutted fish should be sold to the consumer. At the present time, however, it is not unusual to sell ungutted fish like tropical or mediterranean species from foreign countries, even the EC area. In this investigation the influence of gutting on the fish quality during storage on ice was tested in tench (Tinca tinca) as a model. Quality changes were controlled by sensory, chemical, physical and microbiological assessment. It was shown that for tench there were no differences between gutted and ungutted fish during 12 days of storage on ice

Kosten und Nutzen des Strafvollzuges: Grundlagen im Rahmen einer rationalen Kriminalpolitik

Eine rationale Kriminalpolitik zeichnet sich durch ihre Orientierung an einem effizienten System zur Vermeidung von Kriminalität aus. Effizienz bedeutet dabei die Erzielung eines größtmöglichen Erfolgs unter Berücksichtigung gegebener Restriktionen. Eine sehr wichtige Rolle spielt in diesem komplexen System der Bestrafung und der Prävention der Erfolg des Strafvollzugs. Die Erfolgsmessung eines Strafsystems erweist sich als fundamental für die Analyse einer rationalen Kriminalpolitik. Messbare Erfassung von Erfolg oder Misserfolg ist Voraussetzung für die Evaluierung eines bestehenden Strafvollzugs gegenüber alternativen Strafsystemen, und Messbarkeit liefert so die praktischen Grundlagen für eine effiziente und rationale Gestaltung von Justizreformen. Das Erfolgsziel besteht für unseren Strafvollzug in dem maximal erzielbaren Nutzen für unsere Gesellschaft im Sinne von Schutz vor Kriminalität, Rehabilitation usw. Eine rationale Sichtweise verlangt, diesem Nutzen die Kosten des Strafvollzugs - betriebswirtschaftlicher und gesellschaftlicher Art - gegenüber zu stellen. Eine vollständige Evaluation eines Sanktionssystems verlangt folglich - in stark verkürzter Form - die Beantwortung der Frage, ob der Nutzen der Strafmaßnahmen (vermiedene Kriminalität) die Kosten der Strafmaßnahmen überschreitet oder nicht. Der folgende Artikel stellt am Beispiel des Strafvollzugs jene Faktoren vor, die in die in eine Kosten-Nutzen-Analyse einfließen sollten und zeigt zum anderen Probleme auf, die bei der Bestimmung bzw. Erfassung der Kosten-Nutzen-Komponenten auftreten können.

Calorimetric Determination of Energy Levels in Rare-Earth and Yttrium-Iron Garnets

It is shown that low-temperature calorimetry can be a sensitive method for determining the lowest excited energy levels in the rare-earth iron garnets. From Pauthenet\u27s magnetization data one expects the lowest excited levels of several rare-earth ions to become populated at temperatures well below 20°K and to contribute a large specific heat. This property offers the possibility of testing the validity of the Weiss molecular field and spin-wave approximations for this isomorphic series of oxides. After a discussion of the specific heat in terms of the Weiss molecular-field approximation, a spin-wave treatment for the garnets is then presented and the dispersion equation for the acoustical branch is derived. It is shown by a perturbation calculation that in garnets with magnetic rare-earth ions, there are twelve low-lying optical modes that will contribute to the specific heat below 20°K. Heat-capacity measurements between 1.3 and 20.6°K on the iron garnets of Y, Sm, Gd, Tb, Dy, Ho, Er, Yb, and Lu are presented and interpreted in terms of the two theoretical models. The energy levels so obtained are compared to those measured by optical absorption and deduced from magnetic data. For YIG and LuIG, where only the acoustical mode contributes to the magnetic specific heat, the result is compared to other heat-capacity and magnetic measurements. With the exception of TbIG and SmIG the magnetic specific heat of the garnets can be satisfactorily interpreted. Reasonable agreement is obtained in particular between the energy levels as deduced from specific heat data and those observed directly by optical absorption on YbIG and ErIG. In general it is found that for temperatures lower than ~E1/2kB, where E1 is the energy of the lowest excited level and kB the Boltzmann constant, the spin-wave approximation can be used to interpret the results, while for temperatures larger than about E1/6kB the Weiss molecular-field treatment is valid. In the overlapping temperature range, both approximations are equally good. The nuclear magnetic specific heat for TbIG and HoIG is observed and is found to be consistent with the predictions from resonance measurements in other rare-earth compounds

Specific Heat of Some Rare Earth Iron Garnets and YIG at Low Temperatures

Heat capacity measurements of the iron garnets of Y, Gd, Er, Ho, and Yb between 1.4° and 20°K are presented. Below 5°K, the specific heat of YIG can be represented by the sum of a lattice term proportional to T3 and the spin-wave contribution 2.15 × 10−3T3/2 joules/mole-deg. This last term agrees satisfactorily with that calculated from a spin-wave analysis, in which the exchange interaction coefficients were those derived from Pauthenet\u27s magnetization data. The results of the magnetic specific heat of the rare earth ions could be interpreted in terms of a Weiss molecular field acting on these ions. For Gd3+ and Yb3+, this field was found to be, respectively, about 3.0 × 105 and 1.5 × 105 oe below 20°K, in satisfactory agreement with that derived from Pauthenet\u27s data

Anisotropy of the \u3csup\u3e19\u3c/sup\u3eF Chemical Shift of Trapped CHF\u3csub\u3e3\u3c/sub\u3e and NF\u3csub\u3e3\u3c/sub\u3e

We have studied the 19F chemical‐shift anisotropy in NF3 and CHF3 trapped in β‐quinol clathrates. It is known that molecules trapped in these compounds become aligned at low temperatures so that studies of relatively isolated oriented molecules become possible. The nuclear magnetic resonance was observed at several frequencies with the magnetic field applied at various angles relative to the crystal axis. The orientation of the molecules in the cavity and the dipolar broadening due to the lattice protons could be estimated rather closely by a qualitative analysis of the line shapes. The principal components of the chemical‐shift tensor of NF3 could be determined from the observed variation of the first and second moments of the line with the strength and orientation of the magnetic field. This determination was further substantiated by the good agreement between the calculated and observed line shapes for various values of the magnetic field. For CHF3, where the chemical‐shift anisotropy is smaller, only a cruder analysis was practicable. The values of the anisotropy of the chemical‐shift tensor obtained were σ∥−σ⊥ = (390±60) ppm for NF3 and σ∥−σ⊥ = (105±20) ppm for CHF3, where σ⊥ is the average of the two components of the chemical‐shift tensor perpendicular to the fluorine bond direction. For NF3 a difference of (140±40) ppm between the two perpendicular components was found, indicating a deviation from uniaxial symmetry of the NF bond. The sign and order of magnitude of the chemical‐shift anisotropy are discussed and can be understood on the basis of current ideas about the relationship between the bond characters and the chemical‐shift anisotropy

Ökonomisch-kriminologische Evaluation des Justizvollzugs: Mecklenburg-Vorpommern im bundesdeutschen Vergleich

Die vorliegende Dokumentation beinhaltet eine länderspezifische Spezialauswertung einer bundesweiten Feldstudie. Die Erhebung über die Situation der Inhaftierten, der Anstalten und eine vergleichende Analyse der Bundesländer stellen eine in diesem Umfang wohl bisher einzigartige Evaluation des deutschen Strafvollzugs dar. In dieser Kurzversion werden – anhand der Darstellung eines ausgewählten Bundeslandes – beispielhaft die Ergebnisse eines Bundeslandes – Mecklenburg-Vorpommerns - mit bundesweiten Ergebnissen verglichen.

Solid H\u3csub\u3e2\u3c/sub\u3e and D\u3csub\u3e2\u3c/sub\u3e: Remarkable Differences in Some NMR Properties

The differences in the observed properties of solid H2 and D2 are reviewed, and in particular those encountered in NMR experiments. The failure to detect a sharp NMR (I=1) impurity ‘‘isolated pair’’ spectrum in p-D2 is discussed in terms of a larger crystalline field than in H2, where an intense and sharp pair spectrum has been observed. Furthermore, we discuss the dramatic (I=1) solid echo signal loss with decreasing temperature which is observed in solid D2, but not for solid H2. A theory of the solid echo damping through orientational fluctuations is developed. This theory accounts for the observed solid echo decay in D2 as a function of the pulse spacing time τ and leads to an estimation of the order parameter fluctuation amplitude and the correlation time τc. However, the theory cannot account for the loss of spin (as determined from Curie’s law), which must occur for very small values of τ that are not covered by the theory

Sparzwang und Kriminalitätsrisiko: Gibt es Zusammenhänge? : Offene Fragen, und erste Ergebnisse aus einem Forschungsprojekt

Der nachhaltige Sparzwang in Zeiten leerer öffentlicher Kassen wird auch zu Einbußen im Bereich der Kriminalprävention führen, insbesondere im Bereich der Jugend- und der Jugendgerichtshilfe. Die Folgen könnten einen deutlichen Anstieg der Kriminalität bedeuten. Wie dieser Artikel jedoch aufzeigt, sind quantifizierbare Zusammenhänge zwischen (finanziellen und personellen) Inputs und Erfolgen der Kriminalpolitik unklar. Die Gründe hierfür sind mannigfaltig. Ein Defizit besteht in den fehlenden Schätzungen der Kosten in Kriminalität, ferner nimmt Deutschland im Vergleich zu anderen Industrieländern an den regelmäßig durchgeführten internationalen Opferstudien nicht teil. Weitere Mängel bestehen in der für eine Erfolgskontrolle unzureichenden Nutzbarkeit bestehender Rückfallstatistiken sowie in der fehlenden oder mangelhaften Durchführung der Evaluation angebotener Maßnahmen. Der vorliegende Artikel weist auf die Gründe für diese Informationsdefizite hin und zeigt anhand von ersten Forschungsergebnissen des an der TU Darmstadt durchgeführten Forschungsprojektes "Kosten und Nutzen von Haft und Haftvermeidung", welche Erkenntnisse potentiell weiterhelfen könnten