Magnetic bearing momentum wheels with magnetic gimballing capability for 3-axis active attitude control and energy storage

Magnetic bearings used for the suspension of momentum wheels provide conclusive advantages: the low friction torques and the absence of abrasion allow the realization of lightweight high speed wheels with high angular momentum and energy storage capacity and virtually unlimited lifetime. The use of actively controlled bearings provides a magnetic gimballing capability by applying the external signals to the two servo loops controlling the rotational degrees of freedom. Thus, an attitude control system can be realized by using only one rotating mass for 3-axis active satellite stabilization

Doctoral Students\u27 Experience with Using the Reflecting Team Model of Supervision Online

Evidence of the increasing use of technology in counselor education is indicated by the increase in journal articles, programs, websites, and books on this topic (Albrecht & Jones, 2001; Layne & Hohenshil, 2005). The Internet has emerged as an important tool in the training and supervision of counseling students (Conn, Roberts, & Powell, 2009; Watson, 2003). The purpose of this investigation was to explore doctoral students\u27 experience with using the reflecting team (RT) model of supervision online as part of the supervision they received for their internship experience. Five doctoral students and a course instructor from an accredited counselor education and supervision program were the informants for this study. Emerging from the personal narratives of the participants and the subsequent data analysis were several themes related to doctoral students\u27 experience with using the RT model of supervision online. The findings suggest that users\u27 experience of technology, prior supervision experiences, and individual supervisee factors influenced the meaning made of online RT supervision. The results of the study are discussed within a social constructivist framework and provide a foundation for future discussion and future research related to the distance education and supervision of counselors in training. Limitations, implications, and recommendations for counselor educators and supervisors using online RT supervision are provided

The comparative osteology of the skulls of three species of Paralichthys, family Bothidae

This study was undertaken to determine if there were osteological variations in the skulls of young summer flounders, Paralichthys dentatus (Linaeus), southern flounders, Paralichthys lethostigma Jordan and Gilbert and - gulf flounders, Paralichthys albigutta Jordan and Gilbert that could be used as bases of species separation. As two of the species (dentatus and lethostigma) are of considerable economic importance, it would be of substantial value to establish skeletal characters that would help identify the young and. subsequently aid in determining their particular habitats where they occur in the same area.The three are closely related and difficult to recognize unless the pigment pattern is developed separated them primarily by gill raker, anal ray and dorsal ray counts or by correlation of these and considered them to be well defined species acknowledged only two of the three species. They easily separated denaus by numbers of gill rakers, anal rays and dorsal rays; however, they were unable to distinguish lethostigma from z.albigutta and grouped them into a single species, E·albigutta

Haptische Darstellung von Interaktionskräften in einem Assistenzsystem für Herzkatheterisierungen

In den letzten Jahren haben minimalinvasive Operationstechniken die Medizin durch die Ermöglichung komplexer Eingriffe beispielsweise im Bauchraum oder am Herzen durch das für Patienten gegenüber herkömmlichen Operationen geringere Risiko revolutioniert. Einer der Nachteile minimalinvasiver Techniken ist jedoch der Verlust der haptischen Wahrnehmung des Chirurgen. In dieser Arbeit wird daher eine Aktorik für ein Assistenzsystem zur Darstellung haptischer Interaktionskräfte für Herzkatheterisierungen entwickelt. Auf Basis der physiologischen Grundlagen der haptischen Wahrnehmung des Menschen und des Stands der Technik erfolgt im ersten Teil dieser Arbeit eine umfassende Analyse geeigneter Aktorprinzipien. Davon ausgehend wird ein bimodales piezoelektrisches Antriebskonzept entwickelt und aufgebaut. Ein spezieller, bimodal schwingender piezoelektrischer Stapelaktor erzeugt bei einem stabförmigen mechanischen Resonator eine longitudinale und eine transversale Schwingung. Bei einem Resonator mit gebogen Spitze ist eine zweidimensionale Schwingung auch mit einem üblichen symmetrischen Stapelaktoraufbau möglich. Die Überlagerung beider Schwingungen erzeugt an der Spitze des Resonators eine geschlossene Bewegung, die zur Kraftkopplung auf den Führungsdraht genutzt wird. Der Entwurf des Resonators erfolgt zunächst durch analytische Berechnungen. Im Anschluss werden die Ergebnisse mit Hilfe numerischer Lösungsverfahren präzisiert. Im zweiten Teil dieser Arbeit wird der Entwurf und Aufbau eines Verstärkers zur Ansteuerung des piezoelektrischen Aktors dargestellt. Der Verstärker, der ein Ansteuersignal auf eine Spannungsamplitude von 300 V erhöht, zeichnet sich dadurch aus, dass er im Gegensatz zu am Markt erhältlichen Verstärkern trotz der kapazitiven Last des Aktors die Amplitude des hochfrequenten Ansteuersignals nahezu verzerrungsfrei und ohne Dämpfung verstärkt. Die Charakterisierung des piezoelektrischen Ultraschallaktors, die den dritten Themenkomplex dieser Arbeit darstellt, macht die Entwicklung und den Aufbau eines Versuchsumgebung notwendig. In diesem treibt der piezoelektrische Ultraschallaktor eine luftgelagerte Kugel an, deren Rotationsbewegung über zwei optische Sensoren erfasst wird. In verschiedenen Versuchsreihen wird der Einfluss der Amplitude des Ansteuersignals, der Kontaktkraft, der Ansteuerfrequenz sowie der Einfluss von Verschmutzung und der Rauigkeit der Rotoroberfläche auf die gekoppelte Kraft untersucht. Der Erfolg eines neuartigen Assistenzsystems für die Medizintechnik hängt wesentlich von der Gestaltung und der Gebrauchstauglichkeit der Bedieneinheit ab, mit der die Ärzte interagieren. Auf Basis zahlreicher Gespräche mit Kardiologen sowie aus den Ergebnissen einer Designstudie wird abschließend eine Bedieneinheit für das Assistenzsystem entworfe

Generación @

Si la adolescencia fue descubierta a finales del siglo XIX, y se democratizó en la primera mitad del XX, la segunda mitad del siglo ha presenciado la irrupción de la juventud, ya no como sujeto pasivo sino como actor protagonista en la escena pública

A modified and automated version of the 'Fluorimetric Detection of Alkaline DNA Unwinding' method to quantify formation and repair of DNA strand breaks

<p>Abstract</p> <p>Background</p> <p>Formation and repair of DNA single-strand breaks are important parameters in the assessment of DNA damage and repair occurring in live cells. The 'Fluorimetric Detection of Alkaline DNA Unwinding (FADU)' method [Birnboim HC, Jevcak JJ. Cancer Res (1981) 41:1889–1892] is a sensitive procedure to quantify DNA strand breaks, yet it is very tedious to perform.</p> <p>Results</p> <p>In order (i) to render the FADU assay more convenient and robust, (ii) to increase throughput, and (iii) to reduce the number of cells needed, we have established a modified assay version that is largely automated and is based on the use of a liquid handling device. The assay is operated in a 96-well format, thus greatly increasing throughput. The number of cells required has been reduced to less than 10,000 per data point. The threshold for detection of X-ray-induced DNA strand breaks is 0.13 Gy. The total assay time required for a typical experiment to assess DNA strand break repair is 4–5 hours.</p> <p>Conclusion</p> <p>We have established a robust and convenient method measuring of formation and repair of DNA single-strand breaks in live cells. While the sensitivity of our method is comparable to current assays, throughput is massively increased while operator time is decreased.</p

The Great Trade Collapse and the Spanish Export Miracle: Firm-level Evidence from the Crisis

We provide novel evidence on the micro-structure of international trade during the 2008 financial crisis and subsequent global recession by exploring a rich firm-level data set from Spain. The focus of our analysis is on changes at the extensive and intensive firm-level margins of trade, as well as on performance differences (jobs, productivity, and firm survival) across firms that differ in their export status. We find no adverse effects of the financial crisis on foreign market entry or exit, but a considerable increase in the export intensity of firms after the financial crisis. Moreover, we find that exporters were more resilient to the crisis than non-exporters. Finally, while exporters showed a significantly more favorable development of total factor productivity after 2009 than non-exporters, aggregate productivity declined substantially in a large number of industries in Spanish manufacturing. We also briefly explore two factors that might help explain the surprisingly strong export performance of Spain in the aftermath of the great trade collapse: improved aggregate competitiveness due to internal and external devaluation and a substitutive relationship between domestic and foreign sales at the firm level

Analysis of the machinery and intermediates of the 5hmC-mediated DNA demethylation pathway in aging on samples from the MARKAGE Study

Gradual changes in the DNA methylation landscape occur throughout aging virtually in all human tissues. A widespread reduction of 5-methylcytosine (5mC), associated with highly reproducible site-specific hypermethylation, characterizes the genome in aging. Therefore, an equilibrium seems to exist between general and directional deregulating events concerning DNA methylation controllers, which may underpin the age-related epigenetic changes. In this context, 5mC-hydroxylases (TET enzymes) are new potential players. In fact, TETs catalyze the stepwise oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), driving the DNA demethylation process based on thymine DNA glycosylase (TDG)-mediated DNA repair pathway. The present paper reports the expression of DNA hydroxymethylation components, the levels of 5hmC and of its derivatives in peripheral blood mononuclear cells of age-stratified donors recruited in several European countries in the context of the EU Project ‘MARK-AGE’. The results provide evidence for an age-related decline of TET1, TET3 and TDG gene expression along with a decrease of 5hmC and an accumulation of 5caC. These associations were independent of confounding variables, including recruitment center, gender and leukocyte composition. The observed impairment of 5hmC-mediated DNA demethylation pathway in blood cells may lead to aberrant transcriptional programs in the elderly

Age-dependent expression of DNMT1 and DNMT3B in PBMCs from a large European population enrolled in the MARK-AGE study

Aging is associated with alterations in the content and patterns of DNA methylation virtually throughout the entire human lifespan. Reasons for these variations are not well understood. However, several lines of evidence suggest that the epigenetic instability in aging may be traced back to the alteration of the expression of DNA methyltransferases. Here, the association of the expression of DNA methyltransferases DNMT1 and DNMT3B with age has been analysed in the context of the MARK-AGE study, a large-scale cross-sectional study of the European general population. Using peripheral blood mononuclear cells, we assessed the variation of DNMT1 and DNMT3B gene expression in more than two thousand age-stratified women and men (35-75 years) recruited across eight European countries. Significant age-related changes were detected for both transcripts. The level of DNMT1 gradually dropped with aging but this was only observed up to the age of 64 years. By contrast, the expression of DNMT3B decreased linearly with increasing age and this association was particularly evident in females. We next attempted to trace the age-related changes of both transcripts to the influence of different variables that have an impact on changes of their expression in the population, including demographics, dietary and health habits, and clinical parameters. Our results indicate that age affects the expression of DNMT1 and DNMT3B as an almost independent variable in respect of all other variables evaluated

Switching Between Bicyclic and Linear Peptides — The Sulfhydryl-Specific Linker TPSMB Enables Reversible Cyclization of Peptides

Phage display-selected bicyclic peptides have already shown their great potential for the development as bioactive modulators of therapeutic targets. They can provide enhanced proteolytic stability and improved membrane permeability. Molecular design of new linker molecules has led to a variety of new synthetic approaches for the generation of chemically constrained cyclic peptides. This diversity can be useful for the development of novel peptide-based therapeutic, diagnostic, and scientific tools. Herein, we introduce 1,3,5-tris((pyridin-2-yldisulfanyl)methyl)benzene (TPSMB) as a planar, trivalent, sulfhydryl-specific linker that facilitates reversible cyclization and linearization via disulfide bond formation and cleavage of bicyclic peptides of the format CXnCXnC, where X is any proteinogenic amino acid except cysteine. The rapid and highly sulfhydryl-specific reaction of TPSMB under physiological conditions is demonstrated by selecting bicyclic peptide binders against c-Jun N-terminal kinase 3 (JNK3) as a model target. While model peptides remain stably cyclized for several hours in presence of typical blood levels of glutathione in vitro, high cytosolic concentrations of glutathione linearize these peptides completely within 1 h. We propose that reversible linkers can be useful tools for several technical applications where target affinity depends on the bicyclic structure of the peptide