Long nonlinear internal waves

Author Posting. © Annual Reviews, 2006. This article is posted here by permission of Annual Reviews for personal use, not for redistribution. The definitive version was published in Annual Review of Fluid Mechanics 38 (2006): 395-425, doi:10.1146/annurev.fluid.38.050304.092129.Over the past four decades, the combination of in situ and remote sensing observations has demonstrated that long nonlinear internal solitary-like waves are ubiquitous features of coastal oceans. The following provides an overview of the properties of steady internal solitary waves and the transient processes of wave generation and evolution, primarily from the point of view of weakly nonlinear theory, of which the Korteweg-de Vries equation is the most frequently used example. However, the oceanographically important processes of wave instability and breaking, generally inaccessible with these models, are also discussed. Furthermore, observations often show strongly nonlinear waves whose properties can only be explained with fully nonlinear models.KRH acknowledges support from NSF and ONR and an Independent Study Award from the Woods Hole Oceanographic Institution. WKM acknowledges support from NSF and ONR, which has made his work in this area possible, in close collaboration with former graduate students at Scripps Institution of Oceanography and MIT

Menelaus' theorem, Clifford configurations and inversive geometry of the Schwarzian KP hierarchy

It is shown that the integrable discrete Schwarzian KP (dSKP) equation which constitutes an algebraic superposition formula associated with, for instance, the Schwarzian KP hierarchy, the classical Darboux transformation and quasi-conformal mappings encapsulates nothing but a fundamental theorem of ancient Greek geometry. Thus, it is demonstrated that the connection with Menelaus' theorem and, more generally, Clifford configurations renders the dSKP equation a natural object of inversive geometry on the plane. The geometric and algebraic integrability of dSKP lattices and their reductions to lattices of Menelaus-Darboux, Schwarzian KdV, Schwarzian Boussinesq and Schramm type is discussed. The dSKP and discrete Schwarzian Boussinesq equations are shown to represent discretizations of families of quasi-conformal mappings.Comment: 26 pages, 9 figure

The Renin-Angiotensin-Aldosterone system in patients with depression compared to controls – a sleep endocrine study

BACKGROUND: Hypercortisolism as a sign of hypothamamus-pituitary-adrenocortical (HPA) axis overactivity and sleep EEG changes are frequently observed in depression. Closely related to the HPA axis is the renin-angiotensin-aldosterone system (RAAS) as 1. adrenocorticotropic hormone (ACTH) is a common stimulus for cortisol and aldosterone, 2. cortisol release is suppressed by mineralocorticoid receptor (MR) agonists 3. angiotensin II (ATII) releases CRH and vasopressin from the hypothalamus. Furthermore renin and aldosterone secretion are synchronized to the rapid eyed movement (REM)-nonREM cycle. METHODS: Here we focus on the difference of sleep related activity of the RAAS between depressed patients and healthy controls. We studied the nocturnal plasma concentration of ACTH, cortisol, renin and aldosterone, and sleep EEG in 7 medication free patients with depression (1 male, 6 females, age: (mean +/-SD) 53.3 ± 14.4 yr.) and 7 age matched controls (2 males, 5 females, age: 54.7 ± 19.5 yr.). After one night of accommodation a polysomnography was performed between 23.00 h and 7.00 h. During examination nights blood samples were taken every 20 min between 23.00 h and 7.00 h. Area under the curve (AUC) for the hormones separated for the halves of the night (23.00 h to 3.00 h and 3.00 h to 7.00 h) were used for statistical analysis, with analysis of co variance being performed with age as a covariate. RESULTS: No differences in ACTH and renin concentrations were found. For cortisol, a trend to an increase was found in the first half of the night in patients compared to controls (p < 0.06). Aldosterone was largely increased in the first (p < 0.05) and second (p < 0.01) half of the night. Cross correlations between hormone concentrations revealed that in contrast to earlier findings, which included only male subjects, in our primarily female sample, renin and aldosterone secretion were not coupled and no difference between patients and controls could be found, suggesting a gender difference in RAAS regulation. No difference in conventional sleep EEG parameters were found in our sample. CONCLUSION: Hyperaldosteronism could be a sensitive marker for depression. Further our findings point to an altered renal mineralocorticoid sensitivity in patients with depression

Intercultural competence in the psychiatric training curriculum in Germany: Results of a survey

Background: This study was carried out to assess the situation of and the demand for specific training in transcultural psychiatry as part of the residency program in Germany. Method: A semistructured questionnaire with 30 questions (28 structured, 2 open) was developed, for which the "Local Survey of Realities in Transcultural Psychiatry" of the World Psychiatric Association (APA) served as a model and was modified accordingly. This questionnaire was sent out to all directors of psychiatric training institutions in Germany (N = 450). The directors of official psychiatric training institutions are authorized for residency training by the state medical associations. The responses were not anonymous. Results: The return rate was 25.5% (N = 114). In 71.7% of the training institutions (81 out of 113 valid cases), specific training in transcultural psychiatry occurred only rarely or not at all. 83.3% of the directors of psychiatric training institutions (70 out of 84 valid cases) reported a demand for training in transcultural psychiatry in their training institutions; in 94.5% of the cases, the directors of psychiatric training institutions (69 out of 73 valid cases) reported a need for transcultural issues as part of the official curriculum of the psychiatric residency program in Germany. The most frequently reported aspects were teaching of general cultural competence and of culture-specific issues in mental disorders. Implications: Cultural aspects currently are not a mandatory part of the official training curriculum of the psychiatric residency training in Germany. With respect to the reported need for training in cultural issues of mental disorders, the implementation of transcultural psychiatry within the official curriculum of the psychiatric residency training in Germany should be discussed.Zielsetzung: Ziel der vorliegenden Studie ist die Erhebung des Status quo der Weiterbildungssituation in transkultureller Psychiatrie für den Facharzt in Psychiatrie und Psychotherapie in Deutschland. Methodik: Es wurde ein semistrukturierter Fragebogen mit 30 Fragen (davon 28 strukturiert, 2 mit Freitextangaben) entwickelt, der sich an den "Local Survey of Realities in Transcultural Psychiatry" der World Psychiatric Association (APA) anlehnt und für Deutschland modifiziert wurde. Dieser wurde an die Leiter aller psychiatrischen Weiterbildungsinstitutionen in Deutschland verschickt (n=450). Als psychiatrische Weiterbildungsinstitutionen wurden diejenigen klinischen Einrichtungen definiert, deren Leiter über eine Ermächtigung zur Facharztweiterbildung durch die Landesärztekammern verfügen. Der Rücklauf erfolgte nicht anonymisiert. Ergebnisse: Die Rücklaufquote betrug 25,5% (Gesamt-N=114). In 71,7% der Weiterbildungsinstitutionen (n=81/113 gültige Fälle) wurden in der klinikinternen Weiterbildung Themen aus dem Gebiet der transkulturellen Psychiatrie selten oder gar nicht angesprochen. 83,3% der Weiterbildungsleiter (n=70/84 gültige Fälle) formulierten Bedarf an Weiterbildung in transkultureller Psychiatrie für die jeweils eigene Institution, 94,5% (n=69/73 gültige Fälle) sahen den Bedarf grundsätzlich auch für das Curriculum der Facharztausbildung in Psychiatrie und Psychotherapie. Die am häufigsten genannten Themen betrafen eine allgemeine Schulung kultureller Kompetenz sowie kulturspezifische Aspekte seelischer Erkrankungen. Schlussfolgerungen: Im Rahmen der Weiterbildungsordnung zum Facharzt für Psychiatrie und Psychotherapie sind aktuell in keinem Bundesland entsprechende Inhalte aus dem Bereich der transkulturellen Psychiatrie verankert. Angesichts des formulierten Bedarfs muss die Implementierung eines entsprechenden Curriculums in die Weiterbildungsordnung zum Facharzt für Psychiatrie und Psychotherapie diskutiert werden