Actividad física, sedentarismo frente a pantallas y su relación en adolescentes

Programa de Doctorado: Actividad Física, Salud y Rendimiento Deportivo

Nature and origin of ultramafic lamprophyres and carbonatites from the borders of the Labrador Sea

Die Ränder des Labrador Meeres wurden während des späten Neoproterozoikums intensiv von karbonatreichen silikatischen Schmelzen durchsetzt. Diese Schmelzen bildeted sich bei Drucken zwischen ca. 4-6 GPa (ca. 120-180 km Tiefe) an der Basis der kontinentalen Mantel-Lithosphäre. Diese Magmengenerierung steht in zeitlichem und räumlichem Zusammenhang mit kontinentalen Extensionsprozessen, welche zu beiden Seiten des sich öffnenden Iapetus-Ozeans auftraten.

Finite-element discretization of 3D energy-transport equations for semiconductors

In this thesis a mathematical model was derived that describes the charge and energy transport in semiconductor devices like transistors. Moreover, numerical simulations of these physical processes are performed. In order to accomplish this, methods of theoretical physics, functional analysis, numerical mathematics and computer programming are applied. After an introduction to the status quo of semiconductor device simulation methods and a brief review of historical facts up to now, the attention is shifted to the construction of a model, which serves as the basis of the subsequent derivations in the thesis. Thereby the starting point is an important equation of the theory of dilute gases. From this equation the model equations are derived and specified by means of a series expansion method. This is done in a multi-stage derivation process, which is mainly taken from a scientific paper and which does not constitute the focus of this thesis. In the following phase we specify the mathematical setting and make precise the model assumptions. Thereby we make use of methods of functional analysis. Since the equations we deal with are coupled, we are concerned with a nonstandard problem. In contrary, the theory of scalar elliptic equations is established meanwhile. Subsequently, we are preoccupied with the numerical discretization of the equations. A special finite-element method is used for the discretization. This special approach has to be done in order to make the numerical results appropriate for practical application. By a series of transformations from the discrete model we derive a system of algebraic equations that are eligible for numerical evaluation. Using self-made computer programs we solve the equations to get approximate solutions. These programs are based on new and specialized iteration procedures that are developed and thoroughly tested within the frame of this research work. Due to their importance and their novel status, they are explained and demonstrated in detail. We compare these new iterations with a standard method that is complemented by a feature to fit in the current context. A further innovation is the computation of solutions in three-dimensional domains, which are still rare. Special attention is paid to applicability of the 3D simulation tools. The programs are designed to have justifiable working complexity. The simulation results of some models of contemporary semiconductor devices are shown and detailed comments on the results are given. Eventually, we make a prospect on future development and enhancements of the models and of the algorithms that we used.

Experimentelle Untersuchung von Phasenübergängen im kolloidalen Modellsystem harter Kugeln

Die vorliegende Arbeit behandelt den fluid-kristallinen Phasenübergang sowie den Glasübergang anhand von kolloidalen Hart-Kugel(HK)-Modellsystemen. Die Untersuchungen erfolgen dabei im Wesentlichen mit unterschiedlichen Lichtstreumethoden und daher im reziproken Raum. rnDie Analyse der Kristallisationskinetik zeigt, dass es bei der Kristallisation zu signifikanten Abweichungen vom Bild der klassischen Nukleationstheorie (CNT) kommt. Diese geht von einem einstufigen Nukleationsprozess aus, wohingegen bei den hier durchgeführten Experimenten ein mehrstufiger Prozess beobachtet wird. Vor der eigentlichen Kristallisation kommt es zunächst zur Nukleation einer metastabilen Zwischenphase, sogenannter Precursor. In einer zweiten Stufe erfolgt innerhalb der Precursor die eigentliche Nukleation der Kristallite. rnDurch weitere Analyse und den Vergleich des Kristallisations- und Verglasungsszenarios konnte das Konzept der Precursornukleation auf den Vorgang der Verglasung erweitert werden. Während die Kristallnukleation oberhalb des Glasübergangspunktes zum Erliegen kommt, bleibt der Prozess der Precursornukleation auch bei verglasenden Proben erhalten. Ein Glas erstarrt somit in einem amorphen Zustand mit lokalen Precursorstrukturen. Die Korrelation der gemessenen zeitlichen Entwicklung der strukturellen sowie der dynamischen Eigenschaften zeigt darüber hinaus, dass das bisher unverstandene Ageing-Phänomen von HK-Gläsern mit der Nukleation von Precursorn zusammenhängt.rnEin solches mehrstufiges Szenario wurde bereits in früheren Veröffentlichungen beobachtet. Die im Rahmen dieser Arbeit durchgeführten Messungen ermöglichten erstmals die Bestimmung von Kristallnukleationsratendichten (Kristall-NRD) und Ratendichten für die Precursornukleation bis über den Glasübergangspunkt hinaus. Die Kristall-NRD bestätigen die Resultate aus anderen experimentellen Arbeiten. Die weiteren Analysen der Kristall-NRD belegen, dass die fluid-kristalline Grenzflächenspannung bei der Nukleation entgegen den Annahmen der CNT nicht konstant ist, sondern mit ansteigendem Volumenbruch linear zunimmt. Die Erweiterung der CNT um eine linear zunehmende Grenzflächenspannung ermöglichte eine quantitative Beschreibung der gemessenen Kristall- sowie der Precursor-NRD, was den Schluss zulässt, dass es sich in beiden Fällen um einen Boltzmann-aktivierten Prozess handelt. rnUm die beobachteten Abweichungen des Nukleationsprozesses vom Bild der CNT näher zu untersuchen, wurden die kollektiven Partikeldynamiken in stabilen Fluiden und metastabilen Schmelzen analysiert. Im klassischen Bild wird angenommen, dass die kollektive Partikeldynamik beim Vorgang der Nukleation keine Rolle spielt. Anhand der Resultate zeigen sich Abweichungen in der Dynamik stabiler Fluide und metastabiler Schmelzen. Während die kollektive Partikeldynamik in der stabilen Schmelze von der Struktur entkoppelt ist, tritt oberhalb des Phasenübergangspunktes eine Kopplung von Struktur und Dynamik auf. Dabei treten die Abweichungen zunächst in der Umgebung des ersten Strukturfaktormaximums und somit bei den am stärksten besetzten Moden auf. Mit steigender Unterkühlung nehmen die Anzahl der abweichenden Moden sowie die Stärke der Abweichungen zu. Dieses Phänomen könnte einen signifikanten Einfluss auf den Nukleationsprozess und somit auf die Kristallisationskinetik haben. Die Analyse der Dynamik im stabilen Fluid zeigt darüber hinaus Hinweise auf eine Singularität bei Annäherung an den fluid-kristallinen Phasenübergangspunkt.rnDes Weiteren wurden im Rahmen der vorliegenden Arbeit erstmals Ratendichten für die heterogene Nukleation eines HK-Systems an einer flachen Wand mittels statischer Lichtstreuung (SLS) bestimmt. Die Ergebnisse der Messung zeigen, dass die Nukleationsbarriere der heterogenen Nukleation annähernd Null ist und folglich eine vollständige Benetzung der Wand mit einer kristallinen Monolage vorliegt. Die Erweiterung der Untersuchungen auf gekrümmte Oberflächen in Form von sphärischen Partikeln (Seeds) stellt die erste experimentelle Arbeit dar, die den Einfluss eines Ensembles von Seeds auf die Kristallisationskinetik in HK-Systemen untersucht. Die Kristallisationskinetik und die Mikrostruktur werden abhängig von Größe und Anzahldichte der Seed-Partikel signifikant beeinflusst. In Übereinstimmung mit konfokalmikroskopischen Experimenten und Simulationen spielt dabei das Radienverhältnis der Majoritäts- zur Minoritätskomponente eine entscheidende Rolle.

Use of modern and traditional products to self-treat symptoms of sexually transmitted infections in South African women

The objective of the study is to investigate products used by women self-treating symptoms of reproductive tract infections (RTIs), including sexually transmitted infections (STIs), and their methods of administration. A household survey using a multi-stage cluster sample design was undertaken in KwaZulu-Natal, South Africa. Women aged 18-60 years were interviewed (n = 867) and information was collected on demographics, reproductive health and sexual behaviours. A fifth of women reported having RTI/STI symptoms (20.5%), of whom 41.9% were treating these symptoms (mostly discharge [79.1%], ulcers [6.8%] and itching [7.7%]). Only three women were using medication prescribed by a health provider, while the remainder were self-treating using traditional medicines and modern products, including antiseptics, soaps, petroleum jelly, menthol creams and alum. Products were administered in various ways. Although RTI/STI treatment is widely available and free in public health facilities, many women are still self-treating. Potential harm of products for self-treatment requires further investigation and efforts should be made to improve STI service uptake.

"Cutting for love": genital incisions to enhance sexual desirability and commitment in KwaZulu-Natal, South Africa

Several studies have documented women's use of vaginal practices in South Africa to enhance their desirability to men. This article describes a little known practice of this kind among women in KwaZulu-Natal. It involves the use of small incisions in the genital area (and often abdomen and breasts) to introduce herbal substances, described as love medicines, into the body through the incisions. In-depth interviews were carried out with 20 key informants and 20 women, and eight focus group discussions with women and men, in a rural and urban site in 2005-06. A province-wide household survey was then conducted using a multi-stage cluster sample design among 867 women aged 18-60. Forty-two per cent of the women in the household survey had heard of genital incisions; only 3% had actually used them. The main motivation was the enhancement of sexual attractiveness and long-term partner commitment. It appears to be a very recent practice, but may be an extension of an older healing practice not involving the genitals. It was most prevalent among rural women aged 24-29 (although not significant), those with less education, and those who suspected their partners of having other partners. It is linked to the modern popularity of love medicines, which in turn illustrates the troubling state of gender relations in KwaZulu-Natal today.

Hierarchical Approach for Survivable Network Design

A central design challenge facing network planners is how to select a cost-effective network configuration that can provide uninterrupted service despite edge failures. In this paper, we study the Survivable Network Design (SND) problem, a core model underlying the design of such resilient networks that incorporates complex cost and connectivity trade-offs. Given an undirected graph with specified edge costs and (integer) connectivity requirements between pairs of nodes, the SND problem seeks the minimum cost set of edges that interconnects each node pair with at least as many edge-disjoint paths as the connectivity requirement of the nodes. We develop a hierarchical approach for solving the problem that integrates ideas from decomposition, tabu search, randomization, and optimization. The approach decomposes the SND problem into two subproblems, Backbone design and Access design, and uses an iterative multi-stage method for solving the SND problem in a hierarchical fashion. Since both subproblems are NP-hard, we develop effective optimization-based tabu search strategies that balance intensification and diversification to identify near-optimal solutions. To initiate this method, we develop two heuristic procedures that can yield good starting points. We test the combined approach on large-scale SND instances, and empirically assess the quality of the solutions vis-à-vis optimal values or lower bounds. On average, our hierarchical solution approach generates solutions within 2.7% of optimality even for very large problems (that cannot be solved using exact methods), and our results demonstrate that the performance of the method is robust for a variety of problems with different size and connectivity characteristics.

Predictors of vaginal practices for sex and hygiene in KwaZulu-Natal, South Africa: findings of a household survey and qualitative inquiry

Vaginal practices in sub-Saharan Africa may increase HIV transmission and have important implications for development of microbicides and future HIV prevention technologies. It remains unclear which women undertake vaginal practices and what factors predict prevalence, practice type and choice of products. Using cross-sectional data from mixed research methods, we identify factors associated with vaginal practices among women in KwaZulu-Natal, South Africa. Data were gathered through focus group discussions, in-depth and key-informant interviews, followed by a province-wide, multi-stage cluster household survey, using structured questionnaires in face-to-face interviews with 867 women. This paper details six types of vaginal practices, which--despite their individual distinctiveness and diverse motivations--may be clustered into two broad groups: those undertaken for purposes of 'hygiene' (genital washing, douching and application) and those for 'sexual motivations' (application, insertion, ingestion and incisions). Multivariate analysis found significant associations between 'hygiene' practices and media access, religiosity and transactional sex. 'Sexual' practices were associated with partner concurrency, religiosity and use of injectable hormonal contraceptives. Future interventions relating to vaginal practices as well as microbicides need to reflect this characterisation of practices as sexual- and/or hygiene-related.

Schlanke Logistik im Druckmaschinenbau – Wechselwirkungen und Voraussetzungen

Die Bestandteile des Lean Thinking stellen für die moderne Produktion substantielle Prinzipien und Methoden für die Gestaltung effektiver wie auch gleichzeitig effizienter Systeme bereit. Ein unterstützendes Element bilden hier die Ansätze der Schlanken Logistik. Insbesondere die linienorientierte, variantenreiche Großserienproduktion im Automobilbau ist ein wesentlicher Treiber der Entwicklung. Die permanente Adaption auf mehrstufige Produktionssysteme, wie sie speziell im Druckmaschinenbau vorzufinden sind, erscheint dabei konsequent und sinnvoll. Der vorliegende Artikel stellt dabei wesentliche Voraussetzungen für die erfolgreiche Implementierung heraus und beschreibt die jeweiligen Interdependenzen. Schließlich werden ausgewählte Methoden mittels eines kennzahlenbasierten Messmodells anhand eines Fallbeispiels aus dem Druckmaschinenbau quantifiziert bewertet.

Novel prognostic markers revealed by a proteomic approach separating benign from malignant insulinomas.

The prognosis of pancreatic neuroendocrine tumors is related to size, histology and proliferation rate. However, this stratification needs to be refined further. We conducted a proteome study on insulinomas, a well-defined pancreatic neuroendocrine tumor entity, in order to identify proteins that can be used as biomarkers for malignancy. Based on a long follow-up, insulinomas were divided into those with metastases (malignant) and those without (benign). Microdissected cells from six benign and six malignant insulinomas were subjected to a procedure combining fluorescence dye saturation labeling with high-resolution two-dimensional gel electrophoresis. Differentially expressed proteins were identified using nano liquid chromatography-electrospray ionization/multi-stage mass spectrometry and validated by immunohistochemistry on tissue microarrays containing 62 insulinomas. Sixteen differentially regulated proteins were identified among 3000 protein spots. Immunohistochemical validation revealed that aldehyde dehydrogenase 1A1 and voltage-dependent anion-selective channel protein 1 showed significantly stronger expression in malignant insulinomas than in benign insulinomas, whereas tumor protein D52 (TPD52) binding protein was expressed less strongly in malignant insulinomas than in benign insulinomas. Using multivariate analysis, low TPD52 expression was identified as a strong independent prognostic factor for both recurrence-free and overall disease-related survival.

Survival with Newly Diagnosed Metastatic Prostate Cancer in the "Docetaxel Era": Data from 917 Patients in the Control Arm of the STAMPEDE Trial (MRC PR08, CRUK/06/019)

BACKGROUND Prostate cancer (PCa) is the second most common disease among men worldwide. It is important to know survival outcomes and prognostic factors for this disease. Recruitment for the largest therapeutic randomised controlled trial in PCa-the Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy: A Multi-Stage Multi-Arm Randomised Controlled Trial (STAMPEDE)-includes men with newly diagnosed metastatic PCa who are commencing long-term androgen deprivation therapy (ADT); the control arm provides valuable data for a prospective cohort. OBJECTIVE Describe survival outcomes, along with current treatment standards and factors associated with prognosis, to inform future trial design in this patient group. DESIGN, SETTING, AND PARTICIPANTS STAMPEDE trial control arm comprising men newly diagnosed with M1 disease who were recruited between October 2005 and January 2014. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Overall survival (OS) and failure-free survival (FFS) were reported by primary disease characteristics using Kaplan-Meier methods. Hazard ratios and 95% confidence intervals (CIs) were derived from multivariate Cox models. RESULTS AND LIMITATIONS A cohort of 917 men with newly diagnosed M1 disease was recruited to the control arm in the specified interval. Median follow-up was 20 mo. Median age at randomisation was 66 yr (interquartile range [IQR]: 61-71), and median prostate-specific antigen level was 112 ng/ml (IQR: 34-373). Most men (n=574; 62%) had bone-only metastases, whereas 237 (26%) had both bone and soft tissue metastases; soft tissue metastasis was found mainly in distant lymph nodes. There were 238 deaths, 202 (85%) from PCa. Median FFS was 11 mo; 2-yr FFS was 29% (95% CI, 25-33). Median OS was 42 mo; 2-yr OS was 72% (95% CI, 68-76). Survival time was influenced by performance status, age, Gleason score, and metastases distribution. Median survival after FFS event was 22 mo. Trial eligibility criteria meant men were younger and fitter than general PCa population. CONCLUSIONS Survival remains disappointing in men presenting with M1 disease who are started on only long-term ADT, despite active treatments being available at first failure of ADT. Importantly, men with M1 disease now spend the majority of their remaining life in a state of castration-resistant relapse. PATIENT SUMMARY Results from this control arm cohort found survival is relatively short and highly influenced by patient age, fitness, and where prostate cancer has spread in the body.

Measurement of the drift field in the ARGONTUBE LAr TPC with 266 nm pulsed laser beams

ARGONTUBE is a liquid argon time projection chamber (LAr TPC) with a drift field generated in-situ by a Greinacher voltage multiplier circuit. We present results on the measurement of the drift-field distribution inside ARGONTUBE using straight ionization tracks generated by an intense UV laser beam. Our analysis is based on a simplified model of the charging of a multi-stage Greinacher circuit to describe the voltages on the field cage rings.

Multiple metamorphic stages within an eclogite-facies terrane (Sesia Zone, Western Alps) revealed by Th-U-Pb petrochronology

Convergent plate margins typically experience a transition from subduction to collision dynamics as massive continental blocks enter the subduction channel. Studies of high-pressure rocks indicate that tectonic fragments are rapidly exhumed from eclogite facies to midcrustal levels, but the details of such dynamics are controversial.To understand the dynamics of a subduction channel we report the results of a petrochronological study from the central Sesia Zone, a key element of the internalWestern Alps.This comprises two polymetamorphic basement complexes (Eclogitic Micaschist Complex and Gneiss Minuti Complex) and a thin, dismembered cover sequence (Scalaro Unit) associated with pre-Alpine metagabbros and metasediments (Bonze Unit). Structurally controlled samples from three of these units (Eclogitic Micaschist Complex and Scalaro-Bonze Units) yield unequivocal petrological and geochronological evidence of two distinct high-pressure stages. Ages (U-Th-Pb) of growth zones in accessory allanite and zircon, combined with inclusion and textural relationships, can be tied to the multi-stage evolution of single samples.Two independent tectono-metamorphic ‘slices’ showing a coherent metamorphic evolution during a given time interval have been recognized: the Fondo slice (which includes Scalaro and Bonze rocks) and the Druer slice (belonging to the Eclogitic Micaschist Complex).The new data indicate separate stages of deformation at eclogite-facies conditions for each recognized independent kilometer-sized tectono-metamorphic slice, between ~85 and 60 Ma, with evidence of intermittent decompression (∆P~0.5 GPa) within only the Fondo slice. The evolution path of the Druer slice indicates a different P-T-time evolution with prolonged eclogite-facies metamorphism between ~85 and 75Ma. Our approach, combining structural, petrological and geochronological techniques, yields field-based constraints on the duration and rates of dynamics within a subduction channel.

Yellow laser light generation by frequency doubling of the output from a master oscillator fiber power amplifier system

We present a power-scalable approach for yellow laser-light generation based on standard Ytterbium (Yb) doped fibers. To force the cavity to lase at 1154 nm, far above the gain-maximum, measures must be taken to fulfill lasing condition and to suppress competing amplified spontaneous emission (ASE) in the high-gain region. To prove the principle we built a fiber-laser cavity and a fiber-amplifier both at 1154 nm. In between cavity and amplifier we suppressed the ASE by 70 dB using a fiber Bragg grating (FBG) based filter. Finally we demonstrated efficient single pass frequency doubling to 577 nm with a periodically poled lithium niobate crystal (PPLN). With our linearly polarized 1154 nm master oscillator power fiber amplifier (MOFA) system we achieved slope efficiencies of more than 15 % inside the cavity and 24 % with the fiber-amplifier. The frequency doubling followed the predicted optimal efficiency achievable with a PPLN crystal. So far we generated 1.5 W at 1154nm and 90 mW at 577 nm. Our MOFA approach for generation of 1154 nm laser radiation is power-scalable by using multi-stage amplifiers and large mode-area fibers and is therefore very promising for building a high power yellow laser-light source of several tens of Watt.

Meta-analysis identifies seven susceptibility loci involved in the atopic march.

Eczema often precedes the development of asthma in a disease course called the 'atopic march'. To unravel the genes underlying this characteristic pattern of allergic disease, we conduct a multi-stage genome-wide association study on infantile eczema followed by childhood asthma in 12 populations including 2,428 cases and 17,034 controls. Here we report two novel loci specific for the combined eczema plus asthma phenotype, which are associated with allergic disease for the first time; rs9357733 located in EFHC1 on chromosome 6p12.3 (OR 1.27; P=2.1 × 10(-8)) and rs993226 between TMTC2 and SLC6A15 on chromosome 12q21.3 (OR 1.58; P=5.3 × 10(-9)). Additional susceptibility loci identified at genome-wide significance are FLG (1q21.3), IL4/KIF3A (5q31.1), AP5B1/OVOL1 (11q13.1), C11orf30/LRRC32 (11q13.5) and IKZF3 (17q21). We show that predominantly eczema loci increase the risk for the atopic march. Our findings suggest that eczema may play an important role in the development of asthma after eczema.