Generalized vortex model for the inverse cascade of two-dimensional turbulence

We generalize Kirchhoff's point vortex model of two-dimensional fluid motion to a rotor model which exhibits an inverse cascade by the formation of rotor clusters. A rotor is composed of two vortices with like-signed circulations glued together by an overdamped spring. The model is motivated by a treatment of the vorticity equation representing the vorticity field as a superposition of vortices with elliptic Gaussian shapes of variable widths, augmented by a suitable forcing mechanism. The rotor model opens up the way to discuss the energy transport in the inverse cascade on the basis of dynamical systems theory.

High-precision determination of the electric and magnetic form factors of the proton

New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q² = 1 (GeV/c)² with statistical errors below 0.2%. The electric and magnetic form factors of the proton were extracted by fits of a large variety of form factor models directly to the cross sections. The form factors show some features at the scale of the pion cloud. The charge and magnetic radii are determined to be <r²E>½ = 0.879(5)stat(4)syst(2)model(4)group fm and <r²M>½ = 0.777(13)stat(9)syst(5)model(2)group fm.

Surface with antimicrobial activity obtained through silane coating with covalently bound polymyxin B

Surfaces exhibiting antimicrobial activity were prepared for potential medical application. A polycationic lipopeptide polymyxin B was selected as the bioactive agent for covalent immobilization onto the surface. First, by using sol-gel technology the inert glass substrate was functionalized by a silane coating with epoxide rings to which the peptide was coupled by means of a catalyst. Preparation of the coating and presence of the peptide on the surface were followed by FTIR, XPS and AFM analyses. The obtained material showed antimicrobial effect indicating that in spite of immobilization the peptide has retained its bioactivity. The coated surface was able to reduce bacterial cell counts of the Gram-negative bacterium Escherichia coli by more than five orders of magnitude in 24 h of incubation. It can be concluded that bioactive coatings with covalently bound polycationic peptides have potential for application on medical devices where leakage into the surrounding is not allowed in order to prevent bacterial growth and biofilm formation.

Nachweisverfahren zur Beurteilung der Keimbelastung in Einstreumaterialien und des daraus resultierenden Mastitisrisikos

Gegenstand und Ziel: Der Anteil von Mastitiden des Rindes, die durch umweltassoziierte Mikroorganismen verursacht werden, ist in den letzten Jahren gestiegen. Die Anzahl dieser Mikroorganismen im Einstreumaterial beeinflusst die Inzidenz dieser Erkrankungen. Die Studie hat zum Ziel, eine diagnostische Methode und ihre Interpreta tion zu beschreiben, die geeignet ist, das Risiko der Entstehung von Mastitiden durch umweltassoziierte Mikroorganismen aus der Boxeneinstreu einzuschätzen. Material und Methoden: Mittels jeweils 1 g einer frischen Probe an Einstreumaterial (Stroh: n = 406; Späne: n = 281) wurde ein homogenisiertes Wasser-Einstreumaterial-Gemisch gewonnen und zur Erstellung einer Verdünnungsreihe gemäß §64 LFGB Methode L00.00 54 verwendet. Die Ansätze wurden mithilfe des Plattengussbzw. des Spatelverfahrens nach §64 LFGB L01.00–57 zum Nachweis der aeroben Gesamtkeimzahl sowie von Escherichia coli, coliformen Mikroorganismen und äskulinpositiven Streptokokken auf unterschiedlichen (Selektiv-)Nährmedien ausgestrichen. Nach entsprechender Bebrütungszeit erfolgten die Auswertung und die Berechnung der Keimzahlen. Ergebnisse: Die Variabilität der Mikroorganismendichte in üblichen Einstreumaterialien (EM) ist groß. Hygienisch einwandfreie EM weisen nahezu keine coliformen Mikroorganismen oder äskulinspaltende Streptokokken auf und unterschreiten regelmäßig eine Gesamtkeimzahl von < 106 KbE/g aeroben mesophilen Mikroorganismen. Dagegen gibt es optisch einwandfreie, frische organische EM, die bereits vor Anwendung als Boxeneinstreu übliche Grenzwerte der verschiedenen Mikroorganismen überschreiten und damit als risikoreich zu bewerten sind. Schlussfolgerung und klinische Relevanz: Durch die mikrobiologische Untersuchung frischer EM können wichtige Hinweise im Hinblick auf das Risiko für die Entstehung so genannter Umweltmastitiden gewonnen werden. Selbstverständlich sind für die Minderung des Wachstums von Mikroorganismen im Liegebereich der Tiere auch die Kontamination mit Kot, Harn und Milch, die Wechselfrequenz, der Gesamtpflegeaufwand und das Stallklima von Bedeutung.

Investigation of the exclusive 3He(e,e' pn)1H reaction

Cross sections for the 3He(e,e' pn)1H reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming smaller at higher recoil proton momentum.

The Effects of Neuroleptics on Facial Action in Schizophrenic Patients

This paper describes the influence of neuroleptic therapy on facial action in drug-naive schizophrenics. In a comparative study of medicated and unmedicated schizophrenic patients, the coordinates of 12 small light-reflecting points, attached to subjects' faces, were computer-recorded and analyzed automatically during a semi-standardized clinical interview. In addition, facial activity in videotaped interviews was coded using the Facial Action Coding System (FACS). Each sample group comprised of eight patients with the DSM-III-R diagnostic criteria "schizophrenia" or "schizophreniform disorder". Subjects were studied on two occasions, one shortly after admission to the hospital, the other three weeks later. Group 1 was unmedicated during the first session, whereas group 2 was medicated throughout the study. Three weeks after the start of medication, at the second interview, both recording methods showed a reduction in facial activity and facial expression across all subjects in group 1. The facial action of patients in group 2, however, remained unchanged.

2-methylterrylene in hexadecane: do we see single rotational quantum jumps of methyl groups?

We performed comparative low temperature (2-30 K) hole-burning and single molecule experiments with 2-methylterrylene with the goal to detect single rotational tunneling jumps of methyl groups. The hole-burned spectrum with its sharply structured side features which are perfectly symmetrically arranged with respect to the central hole supports the assignment to rotational tunneling transitions. However, instead of one, three clearly distinguishable methyl groups show up in the spectrum. Based on molecular mechanics simulations we attribute them to different, nearly degenerate orientations of guest molecules in one specific site of the hexadecane lattice. The frequency distribution of spontaneous jumps of single molecules reflects the features of the hole-burned spectra, although the distribution in the single molecule experiments is significantly broader. The photoinduced frequency transformation of single molecules ("single molecule photobleaching experiments") fits to the features of the hole-burned spectra, except that, surprisingly, no significant number of spectral jumps could be generated in the frequency range where the prominent narrow antiholes are observed in the hole-burned spectra.