Interpocket polarization model for magnetic structures in rare-earth hexaborides

The origin of peculiar magnetic structures in cubic rare-earth (R) hexaborides RB_6 is traced back to their characteristic band structure. The three sphere-like Fermi surfaces induce interpocket polarization of the conduction band as a part of a RKKY-type interaction. It is shown for the free-electron-like model that the interpocket polarization gives rise to a broad maximum in the intersite interaction I(q) around q=(1/4,1/4,1/2) in the Brillouin zone. This maximum is consistent with the superstructure observed in R=Ce, Gd and Dy. The wave-number dependence of I(q) is independently extracted from analysis of the spin-wave spectrum measured for NdB_6. It is found that I(q) obtained from fitting the data has a similarly to that derived by the interpocket polarization model, except that the absolute maximum now occurs at (0,0,1/2) in consistency with the A-type structure. The overall shape of I(q) gives a hint toward understanding an incommensurate structure in PrB_6 as well.Comment: 5 pages, 3 figures, submitted to J.Phys.Soc.Jp

Non-Collinear Magnetism due to Orbital Degeneracy and Multipolar Interactions

The origin of non-collinear magnetism under quadrupolar ordering is investigated with CeB6 taken as a target system. The mode-mixing effect among 15 multipoles is analyzed based on the Ginzburg-Landau free energy. Then the lower magnetic transition temperature and the order parameters are derived within the mean-field approximation. In the presence of pseudo-dipole-type interactions for the next-nearest neighbors, the observed pattern of non-collinear ordering is indeed stabilized for certain set of interaction parameters. The stability of the phase III' in the magnetic field is also explained, which points to the importance of the next-nearest-neighbor octupole-octupole interaction. Concerning the phase IV in CexLa1-xB6 with x ~ 0.75, a possibility of pure octupole ordering is discussed based on slight modifications of the strength of interactions.Comment: 12 pages, 7 figures, 3 tables, to appear in J. Phys. Soc. Jpn. 70 (6) (2001

Clinical effectiveness of rapid tests for methicillin resistant Staphylococcus aureus (MRSA) in hospitalized patients: a systematic review

<p>Abstract</p> <p>Background</p> <p>Methicillin resistant <it>Staphylococcus aureus </it>(MRSA) are often resistant to multiple classes of antibiotics. The research objectives of this systematic review were to evaluate the clinical effectiveness of polymerase chain reaction (PCR) versus chromogenic agar for MRSA screening, and PCR versus no screening for several clinical outcomes, including MRSA colonization and infection rates.</p> <p>Methods</p> <p>An electronic literature search was conducted on studies evaluating polymerase chain reaction techniques and methicillin (also spelled meticillin) resistant <it>Staphylococcus aureus </it>that were published from 1993 onwards using Medline, Medline In-Process & Other Non-Indexed Citations, BIOSIS Previews, and EMBASE. Due to the presence of heterogeneity in the selected studies, the clinical findings of individual studies were described.</p> <p>Results</p> <p>Nine studies that compared screening for MRSA using PCR versus screening using chromogenic agar in a hospital setting, and two studies that compared screening using PCR with no or targeted screening were identified. Some studies found lower MRSA colonization and acquisition, infection, and transmission rates in screening with PCR versus screening with chromogenic agar, and the turnaround time for screening test results was lower for PCR. One study reported a lower number of unnecessary isolation days with screening using PCR versus screening with chromogenic agar, but the proportion of patients isolated was similar between both groups. The turnaround time for test results and number of isolation days were lower for PCR versus chromogenic agar for MRSA screening.</p> <p>Conclusions</p> <p>The use of PCR for MRSA screening demonstrated a lower turnaround time and number of isolation days compared with chromogenic agar. Given the mixed quality and number of studies (11 studies), gaps remain in the published literature and the evidence remains insufficient. In addition to screening, factors such as the number of contacts between healthcare workers and patients, number of patients attended by one healthcare worker per day, probability of colonization among healthcare workers, and MRSA status of hospital shared equipment and hospital environment must be considered to control the transmission of MRSA in a hospital setting.</p

Fallbeispiele rhinobasaler Raumforderungen im Kleinkindesalter

Fistelöffnungen oder Raumforderungen im Bereich der Nasenwurzel erfordern die Aufmerksamkeit des HNO-Arztes bei der Routineuntersuchung von Kleinkindern und Säuglingen, da sie Hinweis auf komplexe embryonale Fehlbildungen sein können. Im Poster werden die Kasuistiken von zwei Kindern im Alter vom 1 und 3 Jahren vorgestellt. Bei dem 1-jährigen Jungen lag eine Auftreibung der Nasenpyramide und der Nasenwurzel linksbetont und eine komplette Verlegung der Nasenhaupthöhle links durch eine mit Schleimhaut bedeckte, nicht pulsierende, Raumforderung im Bereich der linken Nasenhaupthöhle vor, welche bereits das Septum und die Nasenmuscheln verdrängte. In der MRT und der späteren OP bestätigte sich der Verdacht auf eine große Meningozele mit knöchernem Defekt des Siebbeindaches links und Ausstülpung des Meningozelensackes zwischen knöchernem Nasenseptum und Septumschleimhaut links, woraus sich die Schleimhautbedeckung des Befundes in der Nasenhaupthöhle erklärte.Das 3-jährige Mädchen wurde uns mit einem Grübchen am knöchernen Nasenrücken zur weiteren Diagnostik vorgestellt. Unter dem Untersuchungsmikroskop konnte ein Härchen in der Fistelöffnung gesehen werden. In der Bildgebung zeigte sich verborgen in der knöchernen Nasenwurzel in Verlängerung der Fistel eine Dermoidzyste mit Kontakt zur Dura, welche mitsamt der Fistel operativ entfernt werden konnte. In unserer Posterpräsentation stellen wir die beiden kleinen Patienten, die Bildgebung, den intraoperativen Befund und das definitive histologische Ergebnis vor. Die Fälle sollen das Bewusstsein für die Differentialdiagnose, deren Diagnostik und die Behandlungsoptionen unter Berücksichtigung des wachsenden Nasengerüstes schärfen.Der Erstautor gibt keinen Interessenkonflikt an

From selection to caged aptamers: identification of light-dependent ssdna aptamers targeting cytohesin

Caged aptamers represent valuable tools for the spatiotemporal control of protein function by light. Here we describe a general route starting with the de novo selection process targeting cytohesin-1 and aiming at the synthesis of caged aptamers without the prior knowledge of detailed structural determinants of aptamer-target binding

Raman scattering from spin fluctuations and phonons in the heavy-fermion superconductor UPt3

Quasielastic scattering from spin fluctuations has been observed in UPt3 by Raman spectroscopy. The experiments for wave vectors q≈0 show a nearly temperature independent linewidth for 5 K ≤ T ≤ 300 K Complementary to neutron scattering results this establishes the q independence of the spin relaxation rate, indicating the localized nature of the spin fluctuations. A Raman-active phonon near 79 cm-1 (10 meV) shows a drastic increase in line-width with decreasing temperature, demonstrating strong electron-phonon coupling. © 1987

SOFC modelling based on discrete Bayesian network for system diagnosis use

International audienceWe propose in this paper a diagnosis method that is aimed to detect and isolate SOFC system fault by using the FC stack as a sensor. A discrete Bayesian network (BN) was established to illustrate the input-output causal relations of the stack. In order to examine the generalizability of the network structure, the BN was parameterized to fit the experimental data from two different SOFC systems. Themodels showed reasonable accuracy of state estimation for 6 operating variables. Finally, the BN model was experimented for diagnosing a specified system fault