Experimental and numerical investigation on mixing and axial dispersion in Taylor-Couette flow patterns

Taylor-Couette flows between two concentric cylinders have great potential applications in chemical engineering. They are particularly convenient for two-phase small scale devices enabling solvent extraction operations. An experimental device was designed with this idea in mind. It consists of two concentric cylinders with the inner one rotating and the outer one fixed. Moreover, a pressure driven axial flow can be superimposed. Taylor-Couette flow is known to evolve towards turbulence through a sequence of successive hydrodynamic instabilities. Mixing characterized by an axial dispersion coefficient is extremely sensitive to these flow bifurcations, which may lead to flawed modelling of the coupling between flow and mass transfer. This particular point has been studied using experimental and numerical approaches. Direct numerical simulations (DNS) of the flow have been carried out. The effective diffusion coefficient was estimated using particles tracking in the different Taylor-Couette regimes. Simulation results have been compared with literature data and also with our own experimental results. The experimental study first consists in visualizing the vortices with a small amount of particles (Kalliroscope) added to the fluid. Tracer residence time distribution (RTD) is used to determine dispersion coefficients. Both numerical and experimental results show a significant effect of the flow structure on the axial dispersion

Chandra Monitoring of the Candidate Anomalous X-ray Pulsar AX J1845.0-0258

The population of clearly identified anomalous X-ray pulsars has recently grown to seven, however, one candidate anomalous X-ray pulsar (AXP) still eludes re-confirmation. Here, we present a set of seven Chandra ACIS-S observations of the transient pulsar AX J1845.0-0258, obtained during 2003. Our observations reveal a faint X-ray point source within the ASCA error circle of AX J1845.0-0258's discovery, which we designate CXOU J184454.6-025653 and tentatively identify as the quiescent AXP. Its spectrum is well described by an absorbed single-component blackbody (kT~2.0 keV) or power law (Gamma~1.0) that is steady in flux on timescales of at least months, but fainter than AX J1845.0-0258 was during its 1993 period of X-ray enhancement by at least a factor of 13. Compared to the outburst spectrum of AX J1845.0-0258, CXOU J184454.6-025653 is considerably harder: if truly the counterpart, then its spectral behaviour is contrary to that seen in the established transient AXP XTE J1810-197, which softened from kT~0.67 keV to ~0.18 keV in quiescence. This unexpected result prompts us to examine the possibility that we have observed an unrelated source, and we discuss the implications for AXPs, and magnetars in general.Comment: 4 pages, 3 figures. To be published in the proceedings of the conference "Isolated Neutron Stars: from the Interior to the Surface" (April 24-28, 2006, London, UK), eds. D. Page, R. Turolla, & S. Zan

Proteasome inhibition alleviates prolonged moderate compression-induced muscle pathology

Background: The molecular mechanism initiating deep pressure ulcer remains to be elucidated. The present study tested the hypothesis that the ubiquitin proteasome system is involved in the signalling mechanism in pressure-induced deep tissue injury. Methods. Adult Sprague Dawley rats were subjected to an experimental compression model to induce deep tissue injury. The tibialis region of the right hind limb was subjected to 100 mmHg of static pressure for six hours on each of two consecutive days. The compression pressure was continuously monitored by a three-axial force transducer within the compression indentor. The left hind limb served as the intra-animal control. Muscle tissues underneath the compressed region were collected and used for analyses. Results: Our results demonstrated that the activity of 20S proteasome and the protein abundance of ubiquitin and MAFbx/atrogin-1 were elevated in conjunction with pathohistological changes in the compressed muscle, as compared to control muscle. The administration of the proteasome inhibitor MG132 was found to be effective in ameliorating the development of pathological histology in compressed muscle. Furthermore, 20S proteasome activity and protein content of ubiquitin and MAFbx/atrogin-1 showed no apparent increase in the MG132-treated muscle following compression. Conclusion: Our data suggest that the ubiquitin proteasome system may play a role in the pathogenesis of pressure-induced deep tissue injury. © 2011 Siu et al; licensee BioMed Central Ltd.Link_to_subscribed_fulltex

Artikulationen des Affektiven und die Formierung transkultureller Emotionsrepertoires im Vietnamesischen Berlin

Aus anthropologisch-psychiatrischer Perspektive thematisiert unser Beitrag die Formierung transkultureller Emotionsrepertoires in den Lebensentwürfen vietnamesischer Migrant_innen der ersten Generation in Berlin. Konkret gilt unser empirisches Interesse den affektiven Anstrengungen von Migration, die sich im Leben von vietnamesischen Patient_innen abzeichnen, die psychiatrisch- psychotherapeutische Hilfe in Anspruch nehmen, sowie von deren Angehörigen. Zum einen möchten wir der Frage nachgehen, wann genau affektive Krisenerfahrungen zu Belastungen werden, die auf Basis bisheriger Emotionsrepertoires nicht länger zu bewältigen sind und zu einer Inanspruchnahme psychiatrisch-psychotherapeutischer Hilfe führen. Zum anderen möchten wir Antworten auf die Frage geben, inwiefern diese Inanspruchnahme zu einer Herausbildung neuer und dezidiert transkultureller Emotionsrepertoires beiträgt, die Beheimatungsprozesse begünstigen können, welche in neue und multiple Zugehörigkeiten und/oder Nichtzugehörigkeiten münden (Pfaff-Czarnecka 2012, Scheer 2014, Lähdesmäki et al. 2016, Röttger-Rössler 2016). Die Relevanz der letzteren Frage spiegelt sich in der zunehmenden Akzeptanz vietnamesisch- sprachiger und transkulturell sensibler psychiatrischer Versorgungsan-gebote im Rahmen der Eröffnung zweier Spezialambulanzen in Berlin wider (Ta et al. 2015,Hahn et al. 2016). Diese Versorgungsangebote sind eingebettet in ein aktives Netzwerk, welches die Förderung der seelischen Gesundheit von vietnamesischen Migrant_innen in Deutschland dient und dabei Träger sozialer Hilfen miteinander in Beziehung setzt und auch transnationale psychiatrische Perspektiven miteinbezieht (Ta et al. 2016b). Aus unseren ethnographischen Begegnungen, Beobachtungen und Gesprächen geht hervor, dass das erwähnte Setting in den Spezialambulanzen für unsere Gesprächspartner_innen einen einzigartigen Artikulationsraum darstellt, in dem in bislang ungewohnter Weise und jenseits von Stigmatisierungsängsten über affektive Erfahrungen, Anstrengungen und Belastungen gesprochen werden kann. Wer sich in Vietnam in psychiatrische Behandlung begebe oder in eine psychiatrische Klinik „eingewiesen“ werde, habe es laut unserer Gesprächspartner_innen nicht nur in Bezug auf die Qualität der Versorgung schlechter als in Deutschland: Der-/diejenige werde schnell als điên bezeichnet und müsse mit Diskriminierung und Stigmatisierung in Form eines Gesichtsverlusts rechnen, der sich auch auf das familiäre Umfeld ausweite. Das Wort điên bedeute „verrückt sein“, umgangssprachlich steht es für den medizinischen Ausdruck „an einer psychischen Krankheit leiden“ (bị bệnh tâm thần). Jedoch birgt es durchweg negative Konnotationen in sich, da Menschen, die als điên bezeichnet werden, nicht länger ernst genom-men und aus ihrem sozialen Umfeld ausgegrenzt würden. Affektive Belastungen werden aus diesem Grund häufig verdeckt, um einerseits nicht gegen die Gebote der Wahrung sozialer Harmonie zu verstoßen und andererseits, um eine individuelle und familiäre Stigmatisierung zu vermeiden (Lauber & Rössler 2007, Machleidt 2013). Selbstverständlich gibt es auch in Vietnam vielfältige Bewältigungsstrategien. In Migrationserfahrungen fußende affektive Belastungen beinhalten unserer Meinung nach aber andere Herausforderungen, welche die vertrauten Strategien in dem veränderten sozialen, politischen und wirtschaftlichen Kontext oftmals an ihre Grenzen stoßen lassen. Im Folgenden erläutern wir zunächst, inwiefern wir Affekte von Emotionen im Kontext von Migration konzeptuell unterscheiden und was unter einem transkulturellen Emotionsrepertoire zu verstehen ist. Des Weiteren wird die psychiatrische Ambulanz als ein besonderer Artikulationsraum des Affektiven vorgestellt, sowie auch als Forschungsraum unseres interdisziplinären Projektes. Sodann gewähren wir Einblicke in die Lebensentwürfe von zwei Gesprächspartnern, die beide der ersten Generation vietnamesischer Migrant_innen angehören. Um auch eine transgenerationale Sicht auf Affekte und Emotionen in der Migration zu ermöglichen, beschließen wir unseren empirischen Teil mit einer Beschreibung der Ansichten einer Gesprächspartnerin der zweiten Generation, deren Mutter in psychiatrisch- psychotherapeutischer Be-handlung ist. Unser Beitrag endet mit einer Diskussion, in der wir gängigen Vorstellungen widersprechen, die die Inanspruchnahme psychiatrisch-psychotherapeutischer Hilfe als ein Zeichen von Hilflosigkeit werten und insbesondere Patient_innen mit migrationsbezogenem Hintergrund Handlungsmacht und Kompetenz absprechen (Pratt Ewing 2005, Kirmayer 2007)

Benchmarking in supply chain management: a process to find a better way, rather than an attempt to reinvent the proverbial wheel

In searching for “best practices” in Supply Chain Management, the Asian Benchmarking Clearinghouse (ABC) of Hong Kong Productivity Council (HKPC), jointly with Hong Kong Article Numbering Association (HKANA), conducted a consortium benchmarking study. Through systematic data collection and site visit processes, the consortium group gained critical insights into key issues, challenges and solutions. More importantly, the participated companies were able to identify their positions in the marketplace that were essential for goal setting and attaining superior performance. The Hong Kong Productivity Council shares a same benchmarking methodology with its global alliance partner, American Productivity and Quality Center (APQC). The approach was developed in 1993 and has been serving as one of the premier methods for successful benchmarking in the world

Synthesis and reactions of β-diketiminato heavy group 14 metal alkoxides and phosphanides

Some low-valent, three-coordinated β-diketiminato heavy group 14 metal complexes have been synthesised and their reactions examined. Initially, our attention is focused on several β-diketiminatolead(II) alkoxides. The lead(II) alkoxides show different basic and nucleophilic reactivities from transition metal analogues. For example, the reaction between the lead(II) tert-butoxide and methyl iodide proceeds only under forcing conditions to give the lead(II) iodide and methyl tert-butyl ether. However, facile reversible carbon dioxide insertion into the lead-oxygen bond is observed. To investigate the steric effect of the bulky β-diketiminato ligand, compounds with various aromatic groups attached to nitrogen have been made. When either [(BDIPh)PbCl] (BDIPh = [HC{C(Me)N(C6H5)}2]−) or [(BDIIPP)PbCl] (BDIIPP = [HC{C(Me)N(4-iPrC6H4)}2]−) was treated with potassium tert-butoxide, the reactions gave the unexpected bis[β-diketiminato]lead(II) complexes. However, treatment of [(BDIDMP)PbCl] (BDIDMP = [HC{C(Me)N(2,6-Me2C6H3)}2]−) with AgOTf led to the expected β-diketiminatolead(II) triflate. These results suggest that the ortho-substituent on the N-aryl groups in the β-diketiminato ligand plays an important role in influencing the formation of bis[β-diketiminato]lead(II) complexes. A series of β-diketiminato heavy group 14 metal phosphanides was synthesised. The phosphorus is pyramidally coordinated in the compounds containing diphenyl- or dicyclohexylphosphanido ligands. In contrast, the geometry at phosphorus is planar in the germanium(II) and tin(II) bis(trimethylsilyl)phosphanides. The phosphorus in the lead(II) bis(trimethylsilyl)phosphanide is pyramidally coordinated. The observed conformations may be explained by the steric congestion from the β-diketiminato ligand and electronic effects in the phosphanido ligand. Reactions of the phosphanido complexes with one equivalent of elemental chalcogen give phosphinochalcogenoito complexes. Further reaction with elemental chalcogen gives phosphinodichalcogenoato complexes. In contrast, treatment of the germanium(II) dicyclohexylphosphanide with elemental chalcogen leads to the formation of germanium(IV) chalcogenide. The presence of NMR-active nuclei in these complexes makes possible detailed spectroscopic analysis

Propulsion in a viscoelastic fluid

Flagella beating in complex fluids are significantly influenced by viscoelastic stresses. Relevant examples include the ciliary transport of respiratory airway mucus and the motion of spermatozoa in the mucus-filled female reproductive tract. We consider the simplest model of such propulsion and transport in a complex fluid, a waving sheet of small amplitude free to move in a polymeric fluid with a single relaxation time. We show that, compared to self-propulsion in a Newtonian fluid occurring at a velocity U_N, the sheet swims (or transports fluid) with velocity U / U_N = [1+De^2 (eta_s)/(eta) ]/[1+De^2], where eta_s is the viscosity of the Newtonian solvent, eta is the zero-shear-rate viscosity of the polymeric fluid, and De is the Deborah number for the wave motion, product of the wave frequency by the fluid relaxation time. Similar expressions are derived for the rate of work of the sheet and the mechanical efficiency of the motion. These results are shown to be independent of the particular nonlinear constitutive equations chosen for the fluid, and are valid for both waves of tangential and normal motion. The generalization to more than one relaxation time is also provided. In stark contrast with the Newtonian case, these calculations suggest that transport and locomotion in a non-Newtonian fluid can be conveniently tuned without having to modify the waving gait of the sheet but instead by passively modulating the material properties of the liquid.Comment: 21 pages, 1 figur

Treatment recommendation differences for schizophrenia and major depression: a population-based study in a Vietnamese cohort

Background: In Vietnam, the mental health care infrastructure is on the verge of transformation with an increase in the demand for access to adequate and effective mental health care services. Public attitudes towards mental illness, as well as corresponding treatment options influence help-seeking behaviors of patients and caregivers, affecting the course of their treatment. This study assesses attitudes towards treatment options for depression and schizophrenia, as the two most common psychiatric disorders in Vietnam, accounting for at least 75% of all psychiatric inpatients. Methods: A general population-based survey was conducted in Hanoi, Vietnam between April and August 2013. Participants received a description of a person with symptoms of either depression (n=326) or schizophrenia (n=403) and were asked to give recommendations for adequate sources of mental health support and treatment options. Multiple analyses on a single item level compared the likelihood of recommendation between schizophrenia and depression. Results: Overall, respondents recommended health care services, ranging from seeking mental health care professionals, psychotherapists, and psychiatrists for both disorders. Psychotherapy was the most favored treatment method, whereas further treatment options, such as concentration and relaxation exercises, meditation or yoga and psychotropic medication were also endorsed as helpful. For the schizophrenia vignette condition, psychotherapy, visiting a psychiatrist or psychotherapist received stronger endorsement rates as compared to the depression vignette. Furthermore, ECT, Feng Shui-based practices, praying and visiting natural healers were recommended less by respondents for the depression vignette in comparison with the schizophrenia vignette. Conclusions: The Vietnamese public endorsed evidence-based treatment recommendations from a variety of treatments options. Differences in the treatment recommendations between depression and schizophrenia reflected the perceived severity of each disorder. Further developments of the Vietnamese mental health care system concerning mental health care providers, as well as the legal regulations surrounding the provision of psychotherapy are needed