Tests pour la dépendance entre les sections dans un modèle de Poisson

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L’impact des principes éthiques sur le marché d’assurance en présence de tests génétiques

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Studies on the fracture behaviour of polymer blends with special reference to PP/HDPE and PS/HIPS blends

Investigations on the fracture behaviour of polymer blends is the topic of this thesis. The blends selected are PP/HDPE and PS/HIPS. PP/HDPE blend is chosen due to its commercial importance and PS/HIPS blend is selected to study the transition from brittle fracture to ductile fracture.PP/HDPE blends were prepared at different compositions by melt blending at 180°C and fracture failure process was investigated by conducting notch sensitivity test and tensile test at different strain rates. The effects of two types of modifiers (particulate and elastomer) on the fracture behaviour and notch sensitivity of PP/HDPE blends were studied. The modifiers used are calcium carbonate, a hard particulate filler commonly used in plastics and Ethylene Propylene Diene Monomer (EPDM). They were added in 2%, 4% and 6% by weight of the blends.The study shows that the mechanical properties of PP/HDPE blends can be optimized by selecting proper blend compositions. The selected modifiers are found to alter and improve the fracture behaviour and notch sensitivity of the blends. Particulate fillers like calcium carbonate can be used for making the mechanical behaviour more stable at the various blend compositions. The resistance to notch sensitivity of the blends is found to be marginally lower in the presence of calcium carbonate. The elastomeric modifier EPDM produces a better stability of the mechanical behaviour. A low concentration of EPDM is sufficient to effect such a change. EPDM significantly improves the resistance to notch sensitivity of the blends. The study shows that judicious selection of modifiers can improve the fracture behaviour and notch sensitivity of PP/HDPE blends and help these materials to be used for critical applications.For investigating the transition in fracture behaviour and failure modes, PS/HIPS blends were selected. The blends were prepared by melt mixing followed by injection moulding to prepare the specimens for conducting tensile, impact and flexure tests. These tests were used to simulate the various conditions which promote failure.The tensile behaviour of unnotched and notched PS/HIPS blend samples were evaluated at slow speeds. Tensile strengths and moduli were found to increase at the higher testing speed for all the blend combinations whereas maximum strain at break was found to decrease. For a particular speed of testing, the tensile strength and modulus show only a very slight decrease as HIPS content is increased up to about 40%. However, there is a drastic decrease on increasing the HIPS content thereafter.The maximum strain at break shows only a very slight change up to about 40% HIPS content and thereafter shows a remarkable increase. The notched specimens also follow a comparable trend even though the notch sensitivity is seen high for PS rich blends containing up to 40% HIPS. The notch sensitivity marginally decreases with increase in HIPS content. At the same time, it is found to increase with the increase in strain rate. It is observed that blends containing more than 40% HIPS fail in ductile mode.The impact characteristics of PSIHIPS blends studied were impact strength, the energy absorbed by the test specimen and impact toughness. Remarkable increase in impact strength is observed as HIPS content in the blend exceeds 40%. The energy absorbed by the test specimens and the impact toughness also show a comparable trend.Flexural testing which helps to characterize the load bearing capacity was conducted on PS/HIPS blend samples at the two different testing speeds of 5mmlmin and 10 mm/min. The flexural strength increases with increase in testing speed for all the blend compositions. At both the speeds, remarkable reduction in flexural strength is observed as HIPS content in the blend exceeds 40%. The flexural strain and flexural energy absorbed by the specimens are found to increase with increase in HIPS content. At both the testing speeds, brittle fracture is observed for PS rich blends whereas HIPS rich blends show ductile mode of failure.Photoelastic investigations were conducted on PS/HIPS blend samples to analyze their failure modes. A plane polariscope with a broad source of light was utilized for the study. The coloured isochromatic fringes formed indicate the presence of residual stress concentration in the blend samples. The coverage made by the fringes on the test specimens varies with the blend composition and it shows a reducing trend with the increase in HIPS content. This indicates that the presence of residual stress is a contributing factor leading to brittle fracture in PS rich blends and this tendency gradually falls with increase in HIPS content and leads to their ductile mode of failure.

Export trend of Indian ornamental fish industry

Inspite of having two hotspots of biodiversity India is way long back in the ornamental fish trade. Large number of species can only foster the needs of the industry. The study aims to (1) to find the various indigenous, exotic ornamental fish species and ornamental shrimp species being exported from India, (2) to provide an overview of the trends in the Indian ornamental fish export industry. 287 indigenous fish species, 92 exotic fish species and 44 ornamental shrimps have been found to get exported from India. The export trend of the industry for the past ten years shows a declining state which is also reflected in the annual and compound annual growth rate. Ornamental fish industry has enormous potential in tropical countries like India. To expand trade, new technologies and policies will have to be developed which will help in attaining a sustainable industry.

Attribute reduction and missing value imputing with ANN: prediction of learning disabilities

Learning disability (LD) is a neurological condition that affects a child’s brain and impairs his ability to carry out one or many specific tasks. LD affects about 10% of children enrolled in schools. There is no cure for learning disabilities and they are lifelong. The problems of children with specific learning disabilities have been a cause of concern to parents and teachers for some time. Just as there are many different types of LDs, there are a variety of tests that may be done to pinpoint the problem The information gained from an evaluation is crucial for finding out how the parents and the school authorities can provide the best possible learning environment for child. This paper proposes a new approach in artificial neural network (ANN) for identifying LD in children at early stages so as to solve the problems faced by them and to get the benefits to the students, their parents and school authorities. In this study, we propose a closest fit algorithm data preprocessing with ANN classification to handle missing attribute values. This algorithm imputes the missing values in the preprocessing stage. Ignoring of missing attribute values is a common trend in all classifying algorithms. But, in this paper, we use an algorithm in a systematic approach for classification, which gives a satisfactory result in the prediction of LD. It acts as a tool for predicting the LD accurately, and good information of the child is made available to the concerned

Multi-site time-trend analysis of soil fertility management effects on crop production in sub-Saharan West Africa

Soil fertility constraints to crop production have been recognized widely as a major obstacle to food security and agro-ecosystem sustainability in sub-Saharan West Africa. As such, they have led to a multitude of research projects and policy debates on how best they should be overcome. Conclusions, based on long-term multi-site experiments, are lacking with respect to a regional assessment of phosphorus and nitrogen fertilizer effects, surface mulched crop residues, and legume rotations on total dry matter of cereals in this region. A mixed model time-trend analysis was used to investigate the effects of four nitrogen and phosphorus rates, annually applied crop residue dry matter at 500 and 2000 kg ha^-1, and cereal-legume rotation versus continuous cereal cropping on the total dry matter of cereals and legumes. The multi-factorial experiment was conducted over four years at eight locations, with annual rainfall ranging from 510 to 1300 mm, in Niger, Burkina Faso, and Togo. With the exception of phosphorus, treatment effects on legume growth were marginal. At most locations, except for typical Sudanian sites with very low base saturation and high rainfall, phosphorus effects on cereal total dry matter were much lower with rock phosphate than with soluble phosphorus, unless the rock phosphate was combined with an annual seed-placement of 4 kg ha^-1 phosphorus. Across all other treatments, nitrogen effects were negligible at 500 mm annual rainfall but at 900 mm, the highest nitrogen rate led to total dry matter increases of up to 77% and, at 1300 mm, to 183%. Mulch-induced increases in cereal total dry matter were larger with lower base saturation, reaching 45% on typical acid sandy Sahelian soils. Legume rotation effects tended to increase over time but were strongly species-dependent.

Qualitätssicherung in der Physiotherapie: Evaluation von Performance-Tests

Hintergrund und Ziel: Ausgehend von einem Forschungsdefizit im Bereich von Performance-Tests, das von der Arbeitsgruppe um Bührlen et al. (2002) gekennzeichnet wurde, war es das Ziel der Arbeit einen Performance-Tests of lower limb activities (Polla) zu validieren. Methode: In einer Längsschnittstudie wurden die Ergebnisse einer sechswöchigen physiotherapeutischen Behandlung an einem 19-75jährigem orthopädisch-traumatologisch orientierten Patientenkollektiv (n=81) mit dem Polla und dem SF-36 Fragebogen erfasst. Ergebnisse: Die Ergebnisse machen eine gute Absicherung der Teststatistik deutlich. Bei ausgezeichneter Intrarater- (n=29) sowie guter Interrater-Reliabilität (n=32) weist die Konsistenzanalyse eine zufrieden stellende Zuverlässigkeit auf. Die Kriteriumsvalidität macht moderate Zusammenhänge zwischen dem Polla und den Dimensionen Schmerz, Körperliche Rollenfunktion und Körperliche Funktionsfähigkeit des SF-36 deutlich. Über die Standardized Response Mean zeigen die Instrumente eine große Änderungssensitivität, die nur für den Polla auch zum Follow-up (n=26) gilt. Schlussfolgerung: Der Polla ist ein kostenloses Testverfahren mit hoher praktischer Relevanz, wobei aus zeitökonomischen Gründen eine modifizierte Form des Polla mit nur zehn Items und einem gemessenen Test zu empfehlen ist.

Trend detection in folksonomies

As the number of resources on the web exceeds by far the number of documents one can track, it becomes increasingly difficult to remain up to date on ones own areas of interest. The problem becomes more severe with the increasing fraction of multimedia data, from which it is difficult to extract some conceptual description of their contents. One way to overcome this problem are social bookmark tools, which are rapidly emerging on the web. In such systems, users are setting up lightweight conceptual structures called folksonomies, and overcome thus the knowledge acquisition bottleneck. As more and more people participate in the effort, the use of a common vocabulary becomes more and more stable. We present an approach for discovering topic-specific trends within folksonomies. It is based on a differential adaptation of the PageRank algorithm to the triadic hypergraph structure of a folksonomy. The approach allows for any kind of data, as it does not rely on the internal structure of the documents. In particular, this allows to consider different data types in the same analysis step. We run experiments on a large-scale real-world snapshot of a social bookmarking system.

Entwicklung und Erprobung eines Tests zur "mathematischen Leistungsfähigkeit" deutscher und englischer Lernender in der Sekundarstufe I

Im Rahmen von empirischen Untersuchungen zum Lehren und Lernen von Mathematik haben wir einen Test entwickelt ("Potentialtest"), der die "mathematische Leistungsfähigkeit" von 13/14jährigen Jugendlichen in England und Deutschland für Vergleichszwecke messen soll. Im vorliegenden Beitrag beschreiben wir die Entstehung des Tests sowie Resultate der Durchführung des Tests bei 1036 englischen und deutschen Lernenden. Die Resultate werden unter Berücksichtigung von - aus unseren früheren Fallstudien bekannten - Charakteristika des Mathematikunterrichts in beiden Ländern interpretiert.

Estimators and Tests based on Likelihood-Depth with Application to Weibull Distribution, Gaussian and Gumbel Copula

In dieser Arbeit werden mithilfe der Likelihood-Tiefen, eingeführt von Mizera und Müller (2004), (ausreißer-)robuste Schätzfunktionen und Tests für den unbekannten Parameter einer stetigen Dichtefunktion entwickelt. Die entwickelten Verfahren werden dann auf drei verschiedene Verteilungen angewandt. Für eindimensionale Parameter wird die Likelihood-Tiefe eines Parameters im Datensatz als das Minimum aus dem Anteil der Daten, für die die Ableitung der Loglikelihood-Funktion nach dem Parameter nicht negativ ist, und dem Anteil der Daten, für die diese Ableitung nicht positiv ist, berechnet. Damit hat der Parameter die größte Tiefe, für den beide Anzahlen gleich groß sind. Dieser wird zunächst als Schätzer gewählt, da die Likelihood-Tiefe ein Maß dafür sein soll, wie gut ein Parameter zum Datensatz passt. Asymptotisch hat der Parameter die größte Tiefe, für den die Wahrscheinlichkeit, dass für eine Beobachtung die Ableitung der Loglikelihood-Funktion nach dem Parameter nicht negativ ist, gleich einhalb ist. Wenn dies für den zu Grunde liegenden Parameter nicht der Fall ist, ist der Schätzer basierend auf der Likelihood-Tiefe verfälscht. In dieser Arbeit wird gezeigt, wie diese Verfälschung korrigiert werden kann sodass die korrigierten Schätzer konsistente Schätzungen bilden. Zur Entwicklung von Tests für den Parameter, wird die von Müller (2005) entwickelte Simplex Likelihood-Tiefe, die eine U-Statistik ist, benutzt. Es zeigt sich, dass für dieselben Verteilungen, für die die Likelihood-Tiefe verfälschte Schätzer liefert, die Simplex Likelihood-Tiefe eine unverfälschte U-Statistik ist. Damit ist insbesondere die asymptotische Verteilung bekannt und es lassen sich Tests für verschiedene Hypothesen formulieren. Die Verschiebung in der Tiefe führt aber für einige Hypothesen zu einer schlechten Güte des zugehörigen Tests. Es werden daher korrigierte Tests eingeführt und Voraussetzungen angegeben, unter denen diese dann konsistent sind. Die Arbeit besteht aus zwei Teilen. Im ersten Teil der Arbeit wird die allgemeine Theorie über die Schätzfunktionen und Tests dargestellt und zudem deren jeweiligen Konsistenz gezeigt. Im zweiten Teil wird die Theorie auf drei verschiedene Verteilungen angewandt: Die Weibull-Verteilung, die Gauß- und die Gumbel-Copula. Damit wird gezeigt, wie die Verfahren des ersten Teils genutzt werden können, um (robuste) konsistente Schätzfunktionen und Tests für den unbekannten Parameter der Verteilung herzuleiten. Insgesamt zeigt sich, dass für die drei Verteilungen mithilfe der Likelihood-Tiefen robuste Schätzfunktionen und Tests gefunden werden können. In unverfälschten Daten sind vorhandene Standardmethoden zum Teil überlegen, jedoch zeigt sich der Vorteil der neuen Methoden in kontaminierten Daten und Daten mit Ausreißern.

Valor predictivo de los tests Boehm y Peabody en la detecci??n de futuras dificultades escolares en orden a una intervenci??n preventiva y compensadora

Se analiza la medida en que las pruebas psicopedag??gicas Boehm y Peabody predicen las dificultades en el ??mbito lectoescritor que pueden presentarse en el alumnado de Primaria. Para ello se ha desarrollado un estudio de tipo correlacional en el que se han reunido datos de alumnos desde su ingreso en la Educaci??n Infantil hasta su escolarizaci??n en el segundo ciclo de Educaci??n Primaria. La informaci??n obtenida tiene por tanto, un car??cter diacr??nico. El informe est?? constituido por una breve alusi??n te??rica al problema que se trata para situarse en el lugar preciso donde se centra la investigaci??n, descripci??n de la metodolog??a de investigaci??n, resultados y conclusiones, la discusi??n de los resultados y las propuestas. Se recogen tambi??n la bibliograf??a usada y el estudio de an??lisis de los casos utilizados. Las conclusiones afirman que existe una correlaci??n estad??sticamente significativa entre los tests Peabody y Boehm. Las correlaciones m??s altas son las que implican, de una parte a los tests Peabody y Boehm y, de otra, a las notas escolares de segundo ciclo de Educaci??n Primaria en Matem??ticas y Lengua. Las notas escolares obtenidas por los alumnos del primer ciclo de Educaci??n Primaria en Lengua y Matem??ticas no tienen una correlaci??n estad??sticamente significativa con los tests Boehm y Peabody. En el primer ciclo de Educaci??n Primaria, s??lo el test Peaboy permite predecir las notas escolares en Lengua y Matem??ticas. Estimar y determinar el rendimiento de los alumnos en las citadas asignaturas tomando como punto de partida s??lo los datos aportados por el test Peabody resulta desaconsejable dado el escaso poder predictivo de dicho test. El test Boehm, por su parte, tiene a??n menos poder predictivo sobre las notas escolares y, en el presente estudio, aparece como un mal predictor.

Randomization tests for ABAB designs : Comparing-data-divisionspecific and common distributions. 'Pruebas de aleatorizaci??n para dise??os ABAB : comparaci??n entre distribuciones espec??ficas y comunes'

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Tests de pensamiento creativo de Torrance (TTCT) : elementos para la validez de constructo en adolescentes portugueses.

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RAN : un programa inform??tico para estimar patrones de respuesta aleatorios en tests objetivos

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