Search

We report high accuracy and precision measurements of the shear modulus of colloidal solids formed from monodisperse charged latex spheres contained in an aqueous electrolyte. Standard preparational techniques as well as a recently reported advanced deionization method are applied to prepare transparent, bcc-crystalline samples at precisely controlled low volume fractions Φ= 0.003 and salt concentrations $C_{\rm s}\leq2~\mu$mol l-1. The experimental parameters are found to be extremely stable if certain precautious measures are taken. At constant experimental conditions samples of different morphologies are prepared viacontrolled solidification and further shear processing. Their structure, texture and morphology are analysed by various static light scattering methods. A new, non destructive, time resolved static light scattering technique is used to detect the resonant torsional vibrations excited within a cylindrical sample. Shear moduli in dependence on the concentration of excess electrolyte are calculated from the resonance spectra and compared for several sample morphologies. For the first time a sufficiently high resolution is achieved to clearly discriminate between the influence of the morphology of the sample and of the experimental parameters. We discuss the possible applications of this new approach of high accuracy shear modulus measurements in colloidal crystals to a wide range of interesting experiments.

Background: Motion sickness (MS) is a well-known phenomenon in aviation and in virtual environments such as simulators or computer games. The severity of MS is thought to be due to the amount of sensory conflict, which should increase with the complexity of the simulated motion. The present study focused on the direction and complexity of simulated body rotations in the genesis and severity of visually induced MS. Methods: Three simulated rollercoaster rides including translational movement in the fore-aft axis and additional rotational motion either in pitch only, along the pitch and roll axes, or in pitch, roll, and yaw were generated. We presented video clips of 15 min on a large projection screen to a total number of 61 volunteers, who were randomly assigned to 1 of the 3 rotational motion groups. MS was measured using the Fast Motion Sickness Scale (20-point verbal rating scale) and the Simulator Sickness Questionnaire. Aftereffects were captured up to 5 h after the experiment was finished. Results: Analyses indicated lowest MS scores in the pitch-only condition (1.95). Dual- (4.33) or triple-axis (5.30) combinations revealed significantly higher MS scores than the single-axis condition, but surprisingly did not differ from each other. MS started to subside rapidly after about 1 h past stimulus presentation. Discussion: We conclude that the complexity of visual motion does not increase MS linearly. Instead, we propose that MS reached a plateau in the dual-axis condition and adding a third rotational axis did not further surpass the severity of MS reached. [ABSTRACT FROM AUTHOR]

Background: Performing minimally invasive surgery requires training and visual-spatial intelligence. The aim of our study was to examine the impact of visual-spatial perception and additional mental training on the simulated laparoscopic knot-tying task performed by surgical novices.Methods: A total of 40 medical students randomly assigned to two groups underwent two sessions of laparoscopic basic training on a VR simulator (SimSurgery®, Oslo, Norway). The variables timeand tip trajectory(total path length of the instrument tip trajectory) were used to assess the performance of the intracorporeal knot-tying task using a laparoscopic Nissen fundoplication model. The experimental group completed additional mental practice during the interval between the two training sessions. All performed a cube subtest of a standard intelligence test (I-S-T 2000 R) to evaluate visual-spatial ability.Results: All participants achieved an improvement in time(t= 9.861; p< 0.001) and tip trajectory(t= 6.833; p< 0.001) in the second training session. High scores on the visual-spatial test correlated with a faster performance (r= −0.557; p< 0.001) and more precise movements (r= −0.377; p= 0.016). Comparison of the two groups did not show any statistical significant differences in the parameters timeand tip trajectory.Conclusions: Visual-spatial intelligence tested by a cube test correlated with simulated laparoscopic knot-tying skills in surgical novices. Additional mental practice did not improve the overall knot-tying performance. Further studies are therefore required to determine whether mental practice might be beneficial for experienced laparoscopic surgeons or for more complex tasks.

Zusammenfassung: Psychische Gesundheitsstörungen nach Arbeitsunfällen stellen ein unterschätztes Problem dar. Im Rahmen einer multizentrischen Studie wurden 408 Patienten, die nach Arbeitsunfällen stationär chirurgisch behandelt werden mussten, mittels Screeningbogen in eine Nichtrisiko- (NR) und eine Hochrisikogruppe (HR) eingeteilt und auf ihre nachfolgenden psychischen Reaktionen hin untersucht (4 Messzeitpunkte, 15 Monate Nachbeobachtung). Untersucht wurden Art, Schwere und Häufigkeit psychischer Störungen nach körperlichen Traumen in ihren spontanen Verläufen und ihren Auswirkungen auf die langfristige psychosoziale und berufliche Rehabilitation. Weibliches Geschlecht sowie eine positive Anamnese für mindestens eine psychiatrische Diagnose in der Vorgeschichte scheinen Risikofaktoren für die Zugehörigkeit zur HR-Gruppe zu sein. HR- und NR-Patienten unterschieden sich sowohl bei Studienbeginn als auch im Verlauf in vielen Untersuchungsmerkmalen. Die Ergebnisse unterstreichen erneut die hohe Relevanz dieser Gesundheitsstörungen. Besonderer Handlungsbedarf ergibt sich eindeutig für die Gruppe der Hochrisikopatienten. In ihr zeigten sich über den kompletten Beobachtungszeitraum von 15 Monaten deutlich ungünstigere körperliche, psychische und soziale Heilungsverläufe. Auf diese spezielle, aber auch heterogene Untergruppe sollten sich die klinischen und wissenschaftlichen Bemühungen zur Entwicklung wirksamer Formen der psychologischen Akutbetreuung und Nachsorge konzentrieren.

Zusammenfassung: Im Rahmen der Freiburger Arbeitsunfallstudie wurden 408 Patienten nach schweren Arbeitsunfällen mit stationärer Behandlungspflicht prospektiv auf ihre unmittelbaren und langfristigen psychischen Reaktionen und Folgestörungen hin untersucht. Hinsichtlich des Untersuchungsdesigns und der Epidemiologie wird auf den Beitrag von Südkamp et al. in diesem Heft verwiesen. Im vorliegenden Interventionsteil wurden die kurz- und die langfristige Wirksamkeit einer psychologischen Kurzzeitbehandlung für Hochrisikopatienten überprüft, die kurz nach der Krankenhausaufnahme peritraumatisch besonders intensive psychische Reaktionen gezeigt hatten. 103 mit einem Screeninginstrument ermittelte Hochrisikopatienten wurden entweder der Therapiebedingung (5 Sitzungen Psychotherapie mit präventiver Zielsetzung noch in der Unfallchirurgie) oder der Kontrollbedingung (unfallchirurgische Behandlung ohne spezielle Begleitbehandlung) zugewiesen. Auf Gesamtgruppenebene konnte für die präventive Kurzzeitbehandlung keine Überlegenheit nachgewiesen werden. Nur für Risikopatienten mit anfänglich besonders starken posttraumatischen psychischen Reaktionen ließ sich ein signifikanter Effekt der Therapie im Katamnesezeitraum beobachten. Die Wirksamkeit war spezifisch für das PTBS-Syndrom und nicht generell für andere psychische Beschwerden. Als Schlussfolgerungen werden Fallkonstellationen innerhalb der Risikogruppe diskutiert, für die sich unterschiedlicher (Be)handlungsbedarf ergibt.

AbstractPresent knowledge on peroxiredoxins is reviewed with special emphasis on catalytic principles, specificities and biological function. Peroxiredoxins are low efficiency peroxidases using thiols as reductants. They appear to be fairly promiscuous with respect to the hydroperoxide substrate; the specificities for the donor substrate vary considerably between the subfamilies, comprising GSH, thioredoxin, tryparedoxin and the analogous CXXC motifs in bacterial AhpF proteins. Peroxiredoxins are definitely responsible for antioxidant defense in bacteria (AhpC), yeast (thioredoxin peroxidase) and trypanosomatids (tryparedoxin peroxidase). They are considered to determine virulence of mycobacteria and trypanosomatids. In higher plants they are involved in balancing hydroperoxide production during photosynthesis. In higher animals peroxiredoxins appear to be involved in the redoxregulation of cellular signaling and differentiation, displaying in part opposite effects.

Self-related Experience in the Training of Behavior Therapists: Overview and First Evaluation of a ProgramBackground: During the past years, a growing body of research has documented the importance of scientific evaluation of selfrelated experience (SE) as an element in the training and education of behavior therapists. After a survey of the literature this paper describes the SE concept developed through our research group and a first attempt of its evaluation. Method: Our primary interest was to assess the group experience over the course of 100 hours distributed over 4 weekends. The main focus was on the third weekend, which included an additional evaluation process of participants and group leaders. We further assessed the participants’ expectations as well as their ratings after participation. Results: Results of the group experience indicate that the evaluation on the third weekend stimulated a reflection of intra- and interindividual processes and facilitated new learning experiences. Before starting the SE group, participants mainly expected a development of their basic therapeutic skills (e.g. empathy, positive regard). However, according to the retrospective ratings of the participants, personal aspects of self-experience have been addressed more intensively and their conveyance was rated as more effective. The expectations before beginning SE were generally higher than the ratings of the perceived contents after participation. Conclusions: The results suggest that the value of SE depend on participants’ experience as therapists as well as on duration and level of their training as behavior therapists. Accordingly, the contents of SE should be adapted in a flexible way.

The homo-dimeric structure of a vanadium-dependent haloperoxidase (V-BPO) from the brown alga Ascophyllum nodosum(EC 1.1.11.X) has been solved by single isomorphous replacement anomalous scattering (SIRAS) X-ray crystallography at 2.0 Å resolution (PDB accession code 1QI9), using two heavy-atom datasets of a tungstate derivative measured at two different wavelengths. The protein sequence (SwissProt entry code P81701) of V-BPO was established by combining results from protein and DNA sequencing, and electron density interpretation. The enzyme has nearly an all-helical structure, with two four-helix bundles and only three small β-sheets. The holoenzyme contains trigonal-bipyramidal coordinated vanadium atoms at its two active centres. Structural similarity to the only other structurally characterized vanadium-dependent chloroperoxidase (V-CPO) from Curvularia inaequalisexists in the vicinity of the active site and to a lesser extent in the central four-helix bundle.

The preparation of 3 meat reference materials (bovine muscle, bovine liver and pig kidney) and the steps taken to confirm their homogeneity and stability are described. Details are presented of a preliminary intercomparison and of the final collaborative exercise which led to the certification of the contents of 9 elements of toxicological and nutritional importance. Indicative values are given for the contents of a further 9 elements in these materials.

Abstract: The crystal and molecular structure of 2,7-anhydro-l-glycero-beta-d-manno-octulopyranose has been determined by X-ray analysis. Crystal data area = 9.590(4),b = 7.404(5),c=7.363(4) Å, beta = 101.79(3)°,Z = 2, space groupP21. The phase problem was solved by direct methods, using diffractometer data, and the structure was refined by least-squares techniques to a finalR value of 3.7%. The anhydro ring system is built up by the pyranosyl chair in the1 C 4 conformation, the five-membered ring in theE 0 conformation, and a boat-shaped seven-membered ring. Potential energy calculations show that the positions of the terminal CH2OH groups are determined by hydrogen bonds.

An x-ray analysis of two natural compounds isolated fromPiper sanctum confirmed thetrans configuration for 5-(8-methoxy)cinnamyliden-4-methoxy-but-3-enolide [piperolide (I)] and for 5-[trans-(z)-ß,?-epoxy-a-methoxycinnamyliden]-4-methoxy-2(5H)-furanon [epoxypiperolide (II)]. The space groups arePbca [a = 44.174(3),b = 8.056(3),c = 7.515(4) Å] for (I) andP21/c [a = 11.351(4),b = 8.292(5),c = 14.292(2) Å, ß = 96.28(2) °] for (II). The structures were solved by direct methods and refined by least-squares techniques toR = 4.8% (I) andR = 7.5% (II). The stereochemistry of the semicyclic double bond is in favor of theZ-isomers.

Glucose oxidase (β-d-glucose: oxygen 1-oxidoreductase, EC 1.1.3.4) is an FAD-dependent enzyme that catalyzes the oxidation of β-d-glucose by molecular oxygen. The crystal structure of the partially deglycosylated enzyme from Aspergillus niger has been determined by isomorphous replacement and refined to 2·3 Å resolution. The final crystallographic R-value is 18·1% for reflections between 10·0 and 2·3 Å resolution. The refined model includes 580 amino acid residues, the FAD cofactor, six N-acetylglucosamine residues, three mannose residues and 152 solvent molecules. The FAD-binding domain is topologically very similar to other FAD-binding proteins. The substrate-binding domain is formed from non-continuous segments of sequence and is characterized by a deep pocket. One side of this pocket is formed by a six-stranded antiparallel β-sheet with the flavin ring system of FAD located at the bottom of the pocket on the opposite side. Part of the entrance to the active site pocket is at the interface to the second subunit of the dimeric enzyme and is formed by a 20-residue lid, which in addition covers parts of the FAD-binding site. The carbohydrate moiety attached to Asn89 at the tip of this lid forms a link between the subunits of the dimer. Copyright 1993, 1999 Academic Press

The preparation of 3 meat reference materials (bovine muscle, bovine liver and pig kidney) and the steps taken to confirm their homogeneity and stability are described. Details are presented of a preliminary intercomparison and of the final collaborative exercise which led to the certification of the contents of 9 elements of toxicological and nutritional importance. Indicative values are given for the contents of a further 9 elements in these materials.

Summary This 4–6-year prospective follow-up study compared reactive depressives with (n=48) and without suicide attempts before index admission (n=24). Both groups showed a favourable course and outcome concerning psychiatric diagnoses (DSM-III), psychopathology, social integration, and social functioning as well as displaying a nearly identical course and outcome. In both groups, two patients committed suicide attempts during the follow-up period. 2 (1) male patients from the group with suicide attempts committed suicide.

Thin films of Pt-Ir, Ag-Ir, Ag-Ni and Ag-Y were cocondensed onto sapphire substrates at room temperature. Their atomic structures were investigated by X-ray diffraction. Although the first three systems have endothermic heats of fusion we did not find any sign of decomposition in the Ir containing cocondensed films. Instead, homogeneous solid solutions with fcc structure were formed. For the Ag-Ni system we found partial decomposition. But even here, the solubilities of one component in the other were strongly enhanced with regard to thermodynamical equilibrium. The X-ray diffraction patterns indicate transitions of the two crystalline fcc phases into amorphous states for Ni-contents of about 70 at %. Homogeneous amorphous solid states can be prepared in the Ag-Y system, which has an exothermic heat of fusion. At higher substrate temperatures amorphous and crystalline phases tend to be in metastable equilibrium. The experimental results we present are very suitable to discuss the importance of special material parameters for the formation of amorphous states in cocondensation experiments.

Thin V100-xZrx-films of various compositions (10?x?87) are cocondensed onto hot substrates (280 K?Ts?803 K). The formation area of amorphous films is determined by X-ray diffraction. Crystallization temperatures are measured and crystallization products are identified. The glass formation area extends at room temperature from 15 at%-Zr to 69 at%-Zr. V60Zr40-films become amorphous up to 753 K. The extent of the glass formation area of V-Zr is quite similar to those of Co-Zr and Cu-Zr, although the heats of mixing of the three systems differ enormously. We conclude that the glass formation area of cocondensed Vanadium-Zirconium films is not determined by thermodynamical data, but seems to be dominated by the kinetic constraints of the cocondensation process.

Thin Zr-Mn and Zr-Ta alloy-films were cocondensed onto sapphire substrates at temperatures between 293 K and 923 K. Their structure was investigated by X-ray diffraction and the formation area of amorphous films in the composition/substrate temperature plane was determined. At a substrate temperature of 300 K the glass-forming regions cover a concentration range from 10at%-Zr to 80at%-Zr for Zr-Mn and from 20at%-Zr to 70at%-Zr for Zr-Ta. The formation of amorphous states in cocondensation experiments extends up to substrate temperatures of 873 K for the Zr-Mn and 823 K for the Zr-Ta system. The results are compared to previous investigations of other Zr-TM alloy-systems (TM = Co, Cu, V). The formation areas of these amorphous films are discussed with respect to three parameters: the difference of the atomic radii, the enthalpy of mixing, and the binding energy.

Presents an overview of a measurement-based methodology for dependability evaluation of critical digital systems and describes a software tool under development for it. The approach is based on measurements of operational systems and on dependability models to provide quantitative reliability and availability assessments with stated confidence levels. The methodology is described, and some of the lessons learned in its early use are discussed. The design of a software tool to implement the methodology is outlined and the current experience in applying the methodology is summarized.

Zusammenfassung 1.Wir berichten über Versuche, neben den klassischen Einthovenschen Ableitungen des Elektrokardiogramms Brustwandableitungen zur Beurteilung von Herzkranken heranzuziehen. Wir schlagen vor, den 3 üblichen Ableitungen zwei weitere als 4. und 5. Ableitung hinzuzufügen. Die neuen Ableitungen werden nach der Methode vonWilson mit einer indifferenten (durch Zusammenschluß der 3 Einthovenschen Ableitungsstellen wird eine Elektrode vom Potential Null geschaffen) und einer Suchelektrode ausgeführt: Als Ableitungsstellen an der Brustwand werden empfohlen:a)Der Sternalansatz der 3. Rippe rechts (4. Ableitung).b)Der 6. Intercostalraum in der linken vorderen Axillarlinie (5. Ableitung).2.Bei 50 Herzgesunden ist in der 5. Ableitung T gut ausgebildet. Das Verhältnis der Ausschlagshöhe von T:R beträgt im Mittel 1,0: 4,5.3.Bei 25 Patienten mit arteriellem Hochdruck oder Aortenvitien wird eine Abflachung oder ein Negativwerden von T in der 5. Ableitung beobachtet. Das Verhältnis von T:R=1,0: 7,0 wird als Grenzwert gegen die Norm angenommen. In der 4. Ableitung findet man ein tiefes S und häufig ein positives, dem QRS entgegengerichtetes T.4.Bei 18 Patienten mit unklaren elektrokardiographischen Befunden, die zum Teil in Widerspruch mit den klinischen Befunden stehen, gelingt es mit Hilfe der Brustwandableitungen, ein eindeutiges, den klinischen Befunden ausnahmslos entsprechendes Ergebnis zu erhalten.

The thermophile NADH oxidase from Thermus thermophilus, cloned and expressed in Escherichia coli, has been purified to homogeneity and crystallized. Three different crystal forms were found to be suitable for X-ray diffraction analysis. Crystals of the tetragonal form, grown in the presence of 25% polyethylene glycol 4000 and 0·25 M-NaCl at pH 6·6, were chosen for further analysis. These crystals belong to the space group P4₁₍₃₎2₁2 with refined lattice constants of a = 94·8 Å and c = 49·0 Å, indicating a cell content of one monomer per asymmetric unit of the crystal. The crystals diffract to a resolution of 2·2 Å. Copyright 1993, 1999 Academic Press

Zusammenfassung 1.Für die Ostitis fibrosa cystica generalisata (Recklinghausen) ist pathognomonisch ein verkürztes QT-Intervall im Ekg. Entsprechend dem niederen Calciumspiegel des Tetaniekranken mit langem QT-Intervall ist hier infolge der Hypercalcämie ein besonders kurzes QT-Intervall nachweisbar.2.Nach erfolgreicher Operation (Entfernung eines Neben-schilddrüsenadenoms) sinkt der Calciumspiegel auf normale Werte ab, und das Ekg. zeigt ein normales QT-Intervall. Dieses Verhalten findet sein Gegenstück in den reversiblen Veränderungen des QT-Intervalles nach Calciuminjektionen beim Gesunden und im Tierexperiment.3.Das Ekg. bei der Recklinghausenschen Krankheit ist zunächst nicht als Ausdruck eines „Myokardschadens“ anzusehen. Man wird ferner — ebenso wie beim Tetanie-Ekg. — aus den Veränderungen des QT-Intervalles zunächst nicht auf eine Änderung der mechanischen Systole des Herzens schließen dürfen.