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Search Results: 1 - 10 of 2821 matches for " Guido Haak "
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On a theorem by do Carmo and Dajczer
Guido Haak
Mathematics , 1996,
Abstract: We give a new proof of a theorem by M.P. do Carmo and M. Dajczer on helicoidal surfaces of constant mean curvature.
Discrete surfaces of constant mean curvature via dressing
Guido Haak
Mathematics , 1997,
Abstract: We translate a classification scheme for periodic CMC surfaces developed by J. Dorfmeister and the author to discrete CMC surfaces in the sense of A. Bobenko and U. Pinkall. The scheme uses the dressing action on discrete CMC surfaces to arrive at a classification for periodic discrete CMC surfaces.
Investigation and application of the dressing action on surfaces of constant mean curvature
Josef Dorfmeister,Guido Haak
Mathematics , 1997,
Abstract: We investigate the dressing action on surfaces of constant mean curvature (CMC surfaces) in Euclidean space. In particluar, we show that for CMC surfaces with umbilics the isotropy group under dressing is always trivial. This result is applied to the investigation of CMC surfaces whose metric is invariant under a group of automorphisms of the parameter domain.
On constant mean curvature surfaces with periodic metric
Josef Dorfmeister,Guido Haak
Mathematics , 1996,
Abstract: We investigate CMC-surfaces with periodic metric in a dressing orbit of the cylinder. It is shown, that such surfaces are always of finite type. Using the periodicity conditions for the extended frame of a CMC-surface, we develop an alternative approach to the classification of CMC-tori given by Pinkall and Sterling.
On symmetries of constant mean curvature surfaces
Josef Dorfmeister,Guido Haak
Mathematics , 1996,
Abstract: We start the investigation of immersions $\Psi$ of a simply connected domain $D$ into three dimensional Euclidean space $R^3$, which have constant mean curvature (CMC-immersions), and allow for a group of automorphisms of $D$ which leave the image $\Psi(D)$ invariant. On one hand, this leads to a detailed description of symmetric CMC-surfaces and the associated symmetry groups. On the other hand, it allows us to start the classification of CMC-immersions of an arbitrary, compact or noncompact Riemann surface $M$ into $R^3$ in terms of Weierstrass-type data, as introduced by Pedit, Wu, and one of the authors [D]. We use our general results to prove, that there are no CMC-tori or Delaunay surfaces in the dressing orbit of the cylinder. As an example, we apply the discussion to Smyth surfaces and to a CMC-surface with a branchpoint.
Subthalamic nucleus deep brain stimulation in elderly patients – analysis of outcome and complications
Jan Vesper, Susanne Haak, Christoph Ostertag, Guido Nikkhah
BMC Neurology , 2007, DOI: 10.1186/1471-2377-7-7
Abstract: Bilateral electrode implantation into the subthalamic nucleus (STN) was performed in a total of 73 patients suffering from Parkinson's disease. Patients were analyzed retrospectively. For this study they were divided into two age groups: group I (age <65 years, n = 37) and group II (age ≥ 65 years, n = 36). Examinations were performed preoperatively and at 6-month follow-up intervals for 24 months postoperatively. Age, UPDRS motor score (part III) on/off, Hoehn & Yahr score, Activity of Daily Living (ADL), L-dopa medication, and complications were determined.Significant differences were found in overall performance determined as ADL scores (group I: 48/71 points, group II: 41/62 points [preoperatively/6-month postoperatively]) and in the rate of complications (group I: 4 transient psychosis, 4 infections in a total of 8 patients, group II: 2 deaths [unrelated to surgery], 1 intracerebral hemorrhage, 7 transient psychosis, 3 infections, 2 pneumonia in a total of 13 patients), (p < 0.05). Interestingly, changes in UPDRS scores, Hoehn & Yahr scores, and L-dopa medication were not statistically different between the two groups.DBS of the STN is clinically as effective in elderly patients as it is in younger ones. However, a more careful selection and follow-up of the elderly patients are required because elderly patients have a higher risk of surgery-related complications and a higher morbidity rate.Chronic high-frequency deep brain stimulation (DBS) has evolved into an established therapeutic approach for treating patients with extrapyramidal movement disorders, in particular patients with Parkinson's disease. DBS effectively suppresses tremor and rigor as well as akinesia and dyskinesia [1-14].Numerous studies confirm the safety and efficacy of DBS. Various targets have been used for suppressing specific symptoms. The subthalamic nucleus (STN) is the preferred surgical target for DBS in Parkinson's disease [4,12,15-20].Data on complications of the intervention are inc
Padr?es de consumo de medicamentos em dois povoados da Bahia (Brasil)
Haak,Hildebrando;
Revista de Saúde Pública , 1989, DOI: 10.1590/S0034-89101989000200008
Abstract: a study among families in two villages in rural bahia, brazil, reveals that presently pharmaceutical products, are being used in self - medication on a large scale. traditional remedies appear to have a limited place only. people's attitude towards modern medicines proved to be highy positive. however, when biomedicaly evaluated, the use of the pharmaceutical products has to be considered irrational. complicating factors are: 1) a preference for the application of pharmaceutical products in infants, 2) the high financial burden to which the population is subject resulting from drug acquisition and 3) the exaggerated expectation with regard to antibiotics, analgesics and vitamin preparations. it is recommended did to do more research into local conditions of drugs use, resulting in creative solutions for irrational drug-use. self medication could become an important instrument in "primary health care", provided that people have more information. public health could play a keyrole in this research and the consequent educational programmes.
Group Theoretical Symmetries and Generalized Baecklund Transformations for Integrable Systems
G. Haak
Physics , 1992, DOI: 10.1063/1.530508
Abstract: We present a notion of symmetry for 1+1-dimensional integrable systems which is consistent with their group theoretic description and reproduces in special cases the known Baecklund transformation for the generalized Korteweg-deVries hierarchies. We also apply it to the relativistic invariance of the Leznov-Saveliev systems.
Negative Flows of the KP-Hierarchy
G. Haak
Physics , 1994,
Abstract: We construct a Grassmannian-like formulation for the potential KP-hierarchy including additional ``negative'' flows. Our approach will generalize the notion of a tau-function to include negative flows. We compare the resulting hierarchy with results by Hirota, Satsuma and Bogoyavlenskii.
Within-trial economic evaluation of diabetes-specific cognitive behaviour therapy in patients with type 2 diabetes and subthreshold depression
Nadja Chernyak, Bernd Kulzer, Norbert Hermanns, Andreas Schmitt, Annika Gahr, Thomas Haak, Johannes Kruse, Christian Ohmann, Marsel Scheer, Guido Giani, Andrea Icks
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-625
Abstract: Within-trial economic evaluation of the diabetes-specific cognitive behaviour therapy for subthreshold depression. Patients with diabetes and subthreshold depression are randomly assigned to either 2 weeks of diabetes-specific cognitive behaviour group therapy (n = 104) or to standard diabetes education programme only (n = 104). Patients are followed for 12 months. During this period data on total health sector costs, patient costs and societal productivity costs are collected in addition to clinical data. Health related quality of life (the SF-36 and the EQ-5D) is measured at baseline, immediately after the intervention, at 6 and at 12 months after the intervention. Quality adjusted life years (QALYs), and cumulative costs will be estimated for each arm of the trial. Cost-effectiveness of the diabetes-specific cognitive behaviour group therapy will be analysed from the perspective of the German statutory health insurance and from the societal perspective. To this end, incremental cost-effectiveness ratio (ICER) in terms of cost per QALY gained will be calculated.Some methodological issues of the described economic evaluation are discussed.The trial has been registered at the Clinical Trials Register (NCT01009138).Depression is a highly prevalent disorder with a substantial impact on quality of life and societal cost [1,2]. This applies in particular to patients with diabetes, since depression has been shown to be more prevalent among these patients as compared to those without diabetes [3-5]. Previous research demonstrates that comorbid depression in patients with diabetes is associated with poor self care, i.e. adherence to medication, diet, exercise and smoking cessation [6-8], additive functional impairment and work disability [9], poorer glycaemic control [10], higher risk of microvascular and macrovascular complications [11,12], decreased quality of life [13], and higher mortality [14,15] as compared to patients with diabetes only. Many studies also found high
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