42 research outputs found
The Exact Ground State of the Frenkel-Kontorova Model with Repeated Parabolic Potential: II. Numerical Treatment
A procedure is described for efficiently finding the ground state energy and
configuration for a Frenkel-Kontorova model in a periodic potential, consisting
of N parabolic segments of identical curvature in each period, through a
numerical solution of the convex minimization problem described in the
preceding paper. The key elements are the use of subdifferentials to describe
the structure of the minimization problem; an intuitive picture of how to solve
it, based on motion of quasiparticles; and a fast linear optimization method
with a reduced memory requirement. The procedure has been tested for N up to
200.Comment: 9 RevTeX pages, using AMS-Fonts (amssym.tex,amssym.def), 3 Postscript
figures, accepted by Phys.Rev.B to be published together with
cond-mat/970722
Selecting R&D Projects at BMW: A Case Study of Adopting Mathematical Programming Models
Research and development (R&D) project selection is a critical interface between the product development strategy of an organization and the process of managing projects day-to-day. This article describes the project selection problem faced by an R&D group of BMW (Munich, Germany). The problem was structured as minimizing the gap between target performance of the technology to be developed and actual performance of the current technology along chosen criteria. A mathematical programming model helped this organization to increase the transparency of their selection process, which previously had been based on experience coupled with evaluation of individual projects in isolation Implementation was a success in that the predevelopment group continues to use the model to make better decisions. However, the organization did not use the model for its intended purpose: constrained optimization. The traditional explanation for this partial implementation is that the analytical model did not capture all considerations relevant to optimization (e.g., uncertainty or strategic fit), and that further model refinements are required to achieve further implementation. We offer an alternative explanation, one based on the technology transfer literature. The diffusion of the analytical model from academia to industry faced the same problems as any technology transfer: Significant tacit knowledge had to be transferred along with the codified knowledge of the analytical model. This required iterated problem solving, which required the limited time and resources of the diffusing agents (academia) as well as the adopting agents (industry). Thus, the organization adopted only those elements of the modeling method that could be transferred within the resource constraints, focusing on those elements offering the highest benefit per effort invested
Neutrophil gelatinase-associated lipocalin (NGAL) predicts the occurrence of malaria-induced acute kidney injury
Joseph Franz Barwirsch levele Luk谩cs Gy枚rgynek
_Background:_ Acute kidney injury (AKI) is a frequently encountered complication of imported Plasmodium falciparum infection. Markers of structural kidney damage have been found to detect AKI earlier than serum creatinine-based prediction models but have not yet been evaluated in imported malaria. This pilot study aims to explore the predictive performance of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) for AKI in travellers with imported P. falciparum infection.
_Methods:_ Thirty-nine patients with imported falciparum malaria from the Rotterdam Malaria Cohort with available serum and urine samples at presentation were included. Ten of these patients met the criteria for severe malaria. The predictive performance of NGAL and KIM-1 as markers for AKI was compared with that of serum creatinine.
_Results:_ Six of the 39 patients (15 %) developed AKI. Serum and urine NGAL and urine KIM-1 were all found to have large areas under the receiver operating characteristics curves (AUROC) for predicting AKI. Urine NGAL was found to have an excellent performance with positive predictive value (PPV) of 1.00 (95 % CI 0.54-1.00), a negative predictive value (NPV) of 1.00 (95 % CI 0.89-1.00) and an AUROC of 1.00 (95 % CI 1.00-1.00).
_Conclusion:_ A good diagnostic performance of NGAL and KIM-1 for AKI was found. Particularly, urine NGAL was found to have an excellent predictive performance. Larger studies are needed to demonstrate whether these biomarkers are superior to serum creatinine as predictors for AKI in P. falciparum malaria
Development of patient-derived xenograft models from a spontaneously immortal low-grade meningioma cell line, KCI-MENG1
Caracter铆sticas del liderazgo pedag贸gico del directivo docente de la I.E. de Jes煤s del municipio de Concordia
Esta investigaci贸n abord贸 el liderazgo pedag贸gico, espec铆ficamente el liderazgo directivo, su papel dentro del proceso pedag贸gico de la instituci贸n educativa est谩 justificado por la relevancia que tiene en la gesti贸n curricular, entre otras funciones, pues permite que las instituciones educativas - I.E marchen adecuadamente y alcancen mayores logros para todos los estudiantes. El objetivo consisti贸 en identificar las caracter铆sticas del liderazgo pedag贸gico del directivo docente de la I.E de Jes煤s del municipio de Concordia. Para esto se consider贸 una investigaci贸n enmarcada dentro del enfoque cualitativo de tipo descriptivo, el m茅todo fue estudio de caso. Los instrumentos que se utilizaron fueron, la entrevista, el diario de campo y el grupo focal. Con base en los resultados obtenidos en las entrevistas se destacan aspectos importantes de la comunicaci贸n y el liderazgo, vinculados a la gesti贸n administrativa de la I.E. La investigaci贸n muestra la importancia que tiene el liderazgo pedag贸gico del directivo docente como elemento clave en el desarrollo y funcionamiento pedag贸gico-curricular de la I.E.This research addressed pedagogical leadership, such as one that focuses on the directive role, specifically on his role in the educational process on the educative institution; the relevance it's justified for this process for function properly on the institutions to and achieve greater achievements for all students. The objective was to identify the pedagogical leadership from the educative director of the Educative Institution of Jesus from the Concordia municipality. For this, was considered an investigation framed within the qualitative approach of descriptive type, the method was a study case. The instruments used were interview, field diaries and focus group. Based on the interview results obtained, important aspects of communication and leadership were highlighted, linked to the development processes on the educative institution. The research shows the importance on a pedagogical leadership of the teaching director as a key element within the institution.Mag铆ster en Educaci贸nMaestr铆