The railroad industry is pivotal in the United States to ensure that the supply chain does not shut down for the American people. Non-Destruction Evaluation (NDE) approaches are preferred and performed on the railways to ensure the safety of the population that is exposed to the railway industry. When damage occurs on the rail base, there is an increased risk derailment of the train cars. Due to the nature of the railroad industry, there are challenges with developing a quick and reliable inspection method, along with the improvement of current NDE methods. The load, speed, and cycles of trains have increased the load that track sections endure over time. Some railways that were originally built in the early 20th century are still utilized today, designed for trains that are not nearly as heavy or fast as used today. Defects and damage on the railways lead to the need of development of an NDE approach utilizing Line Scan Thermography approaches. One of the most common defects that are formed are on the rail base is known as “base nicks” and “half-moon cracks”, these types of defects can occur over time. This research aims to study the feasibility of applying this NDE technique to detect defects that can occur on a rail base, both internal and external. For this research, a heat source up to 6000 W and tested velocities up to 447.1 mm/s (1.0 mph) are used to study the effects of line scanning thermography on various samples. In total, 10 samples are employed to test for feasibility: each one having a unique set of defects. Some defects fabricated on these samples are internal, such as bottom drilled holes (BDH) and side drilled holes (SDH); some of these samples are fabricated from actual rail samples. From tests conducted for internal defects, it can be concluded that defects with diameters of 6.35 mm (0.25”) can be detected at a remaining thickness from the observation surface of 6.35 mm. Along with internal defects, there are also external defects employed on the samples; these defects include simulated base nicks, fractures, and half-moon cracks. For surface defects tests from this research, it is found that the anomalies can be detected visually. The results from the experimental studies provide insight and limitations of LST for the possibility of a future commercial application.

In den letzten fünf Jahren gelang es, drei neue genetische Krankheitsbilder aus dem Kreis der pädiatrischen Endokrinologie klinisch zu beschreiben und deren genetische Grundlage aufzuklären. Hierbei waren vor allem die klinischen Erscheinungsbilder ungewöhnlicher Patienten, die neben bekannten hormonellen Ausfällen durch assoziierte Defekte auffielen, für die gezielte Suche nach genetischen Defekten ausschlaggebend. In allen drei Fällen konnten die assoziierten Symptome durch den primären genetischen Defekt molekular geklärt werden. Mittlerweile ist bei weiteren Patienten ein Mutationsnachweis gelungen und der zuerst von uns beschriebene Phänotyp konnte jeweils bestätigt werden. Bei den beschriebenen defekten handelt es sich um den POMC Gendefekt (klinisches Bild: Adipositas, rote Haarfarbe und Hypocortisolismus), den LHX3 gendefekt (klinisches Bild: Hypopituitarismus und Enschränkung der Haslrotation) und den NKX2.1 Gendefekt (klinisches Bild: Angeborene Hypothyreose und Choreoathetose). / In the last few years'' three new genetic syndromes were described which affect diseases within the field of paediatric endocrinology. The clinical picture of uncommon patients, which are affected beside known endocrine defects by additional associated symptoms, led to the molecular differential diagnosis which resulted in the description of new mutations. In all three cases the additional symptoms could be explained by the identified genetic defect. Meanwhile additional patients were identified with mutations in the affected genes, which confirmed the initial description of the new clinical diseases. The identified syndromes are: POMC gene defect (clinical picture: obesity, red hair, hypocortisolism), LHX3 gene defect (clinical picture: hypopituitarism and decreased neck movement) and NKX2.1 gene defect (clinical picture: congenital hypothyroidism and choreoathetosis).

Recombination mechanisms in gallium arsenide have been studied using temperature-dependent time-resolved photoluminescence-decay. New analytical methods are presented to improve the accuracy in bulk lifetime measurement, and these have been used to resolve the temperature-dependent lifetime. Fits to temperature-dependent lifetime yield measurement of the radiative-efficiency, revealing that samples grown by the Czochralski and molecular-beam-epitaxy methods are limited by radiative-recombination at 77K, with defect-mediated nonradiative-recombination becoming competitive at 300K and above. In samples grown with both doping types using molecular-beam-epitaxy, a common exponential increase in capture cross-section characterized by a high value of E_infinity=(258 +/- 1)meV was observed from the high-level injection lifetime over a wide temperature range (300-700K). This common signature was also observed from 500-600K in the hole-lifetime observed in n-type Czochralski GaAs where E_infinity=(261 +/- 7)meV was measured, which indicates that this signature parametrizes the exponential increase in hole-capture cross-section. The high E_infinity value rules out all candidate defects except for EL2, by comparison with hole-capture cross-section data previously measured by others using deep-level transient spectroscopy. / Thesis / Doctor of Philosophy (PhD)

No description available.

De nos jours, l'essor des produits électroniques nomades requièrent une capacité de stockage de données croissante et imposent la fabrication de composants mémoire performants, denses et fiables. Cela implique une grande robustesse des cellules mémoires élémentaires dont les dimensions caractéristiques sont régulièrement réduites. L'objectif principal de la thèse est d'appréhender les mécanismes de claquage d'oxydes minces voire ultraminces intégrés dans des empilements métal/oxyde/semiconducteur. Un intérêt particulier a été porté à la croissance d'îlots cristallins épitaxiés se formant lors de certaines sollicitations électriques et associée aux mécanismes de DBIE (Dielectric Breakdown Induced Epitaxy). L'étude des différents dispositifs (cellules mémoires à grille continue ou discrète, transistors, condensateur) a permis de proposer des corrélations entre la défaillance électrique de ces dispositifs et les défauts microstructuraux générés. Ce travail a été réalisé selon une méthodologie intégrant (i) la sollicitation électrique ; (ii) une préparation d'échantillons adaptée ; (iii) l'identification, l'observation et la caractérisation des défauts par microscopie électronique en transmission (TEM). L'ensemble des études menées a permis d'isoler deux paramètres électriques principaux ayant un rôle prépondérant sur la formation d'îlots de silicium épitaxiés, en lien avec le mécanisme de DBIE : la charge injectée et le courant de compliance. Ces deux paramètres apparaissent comme des facteurs limitant l'emballement thermique qui conduit, en général, à un claquage diélectrique franc de l'oxyde et semblent, par conséquent, retarder la défaillance irréversible d'un dispositif. / Nowadays, the microelectronic industry had to take up ambitious challenges to satisfy the strong economic demand because of the mobile electronic products booming like smartphones, tablets, or more recently "phablets". These high added value products requires the growth of data storage capacity and, subsequently, to produce high-performance, dense and reliable components. That implies a great cell memories robustness whose critical dimensions are regularly reduced. In this context, the thesis issue is to better understand the breakdown mechanisms of the thin and ultra-thin oxides embedded in metal/oxide/semiconductor stacks. Actually, epitaxial growth of crystalline silicon hillocks was pinpointed. These hillocks grown under electrical stresses and were associated to DBIE mechanisms (Dielectric Breakdown Induced Epitaxy). Device studies allowed to correlate electrical stress conditions and microstructural defects thanks to a 3-steps methodology : (i) electrical stresses leading to microstructural defects ; (ii) sample preparation including defect localization and extraction ; (iii) identification, observation and characterization of defects by transmission electron microscopy (TEM). Two main electrical parameters were identified with factors responsible for hillocks growth linked to DBIE : the injected charge and the compliance current. These parameters seem to limit the thermal runaway inducing hard breakdown. Consequently, it is possible that delays the irreversible device degradation. In addition, hillocks seem to grow preferentially under polysilicon grain boundaries over the SiO2/Si stacks.

<p>To assess the impact of congenital malformations in Down syndrome (DS) on morbidity, mortality and outcome at birth, information on all children with DS born in the northern part of Sweden in 1973-80 (n=211) and 1995-98 (n=88) was collected. Most common were congenital heart defects (CHD), dominated by atrioventricular septal defects (AVSD). Up to age 10 years, morbidity and mortality were more than 10 times higher in DS children with CHD than in healthy DS children. The DS children seemed more vulnerable at birth than Swedish children in general: they had increased frequencies of Cesarean sections, premature birth, asphyxia, and low birthweight, and higher proportions of children small for gestational age, regardless of the presence of CHD. Infant mortality decreased from 14.2% to 2.3% between the two periods.</p><p>All children with AVSD with and without DS born in Sweden 1973-1997 (n=801) were followed up retrospectively to 2001. Children with isolated AVSD without complex additional CHDs were studied more closely (n=502). A reduction in age at operation and postoperative mortality (from 28 to 1%) was observed. No significant difference in 5-year postoperative mortality between genders or between DS and non-DS children was found. The 5-year postoperative mortality in DS decreased from 35% in 1973-77 to about 10% in 1993-97. </p><p>CHD had a major influence on morbidity, infectionrate and mortality in DS, but not on DS birth variables. The formerly high mortality in CHD is now reduced. In isolated AVSD measures seem equally successful in DS and non-DS children. Mortality is still 3 times higher in DS children with isolated AVSD than in healthy DS children. </p>

To assess the impact of congenital malformations in Down syndrome (DS) on morbidity, mortality and outcome at birth, information on all children with DS born in the northern part of Sweden in 1973-80 (n=211) and 1995-98 (n=88) was collected. Most common were congenital heart defects (CHD), dominated by atrioventricular septal defects (AVSD). Up to age 10 years, morbidity and mortality were more than 10 times higher in DS children with CHD than in healthy DS children. The DS children seemed more vulnerable at birth than Swedish children in general: they had increased frequencies of Cesarean sections, premature birth, asphyxia, and low birthweight, and higher proportions of children small for gestational age, regardless of the presence of CHD. Infant mortality decreased from 14.2% to 2.3% between the two periods. All children with AVSD with and without DS born in Sweden 1973-1997 (n=801) were followed up retrospectively to 2001. Children with isolated AVSD without complex additional CHDs were studied more closely (n=502). A reduction in age at operation and postoperative mortality (from 28 to 1%) was observed. No significant difference in 5-year postoperative mortality between genders or between DS and non-DS children was found. The 5-year postoperative mortality in DS decreased from 35% in 1973-77 to about 10% in 1993-97. CHD had a major influence on morbidity, infectionrate and mortality in DS, but not on DS birth variables. The formerly high mortality in CHD is now reduced. In isolated AVSD measures seem equally successful in DS and non-DS children. Mortality is still 3 times higher in DS children with isolated AVSD than in healthy DS children.

No description available.

Die Entwicklung innovativer Therapiekonzepte für die Knochenregeneration erfordert validierte segmentale Knochendefekt-Tiermodelle. Dabei ist das Mausmodell für die präklinische Testung von zentraler Bedeutung, jedoch fehlen in der wissenschaftlichen Literatur bislang Angaben zu validierten, extern stabilisierenden kritischen segmentalen Knochendefektmodellen an der immundefizienten Maus. Das Ziel dieser Arbeit war daher die Entwicklung und in vivo Evaluierung eines zuverlässigen und einfach zu handhabenden Modells für extern stabilisierte kritische Knochendefekte an der immundefizienten Maus. Dreißig männliche nu/nu-Mäuse (40,7±2,8 g, 95±2,6 d) wurden mittels Isofluraninhalation narkotisiert und anschließend ein externer Fixateur (MouseExFix, RISystem, AO Research Institute Davos, Schweiz) am rechten Femur angebracht. Femorale Knochendefekte der Länge 1 mm (n=10), 2 mm (n=10) und 3 mm (n=10) wurden erzeugt. Der Wundverschluss erfolgte mit Einzelknopfnähten. Röntgenaufnahmen wurden unmittelbar postoperativ und im Folgenden alle zwei Wochen innerhalb des Beobachtungszeitraums von zwölf Wochen angefertigt und im Hinblick auf Knochenregeneration und –fusion ausgewertet. Weiterhin wurden histomorphologische, histomorphometrische, immunhistochemische und µCT-Analysen zur dreidimensionalen und zellulären Beurteilung der Knochenheilung angefertigt. Alle Tiere überlebten die Operation. Sechs Tiere starben innerhalb des Beobachtungszeitraums als Folge von starkem Blutverlust (n=1), Infektion (n=1), Pinlockerung, welche die Euthanasie erforderlich machte (n=2) und durch Komplikationen bei der Anästhesie (n=2). Die µCT-Analyse nach zwölf Wochen zeigte, dass 3/8 der 1 mm-Defekte, 5/8 der 2 mm-Defekte und 8/8 der 3 mm-Defekte eine Pseudarthrose aufwiesen. Das mittlere Defektvolumen stieg signifikant (p<0,001) mit der Größe des Defektes und betrug 0,36±0,42 mm³ (1 mm-Gruppe), 1,4±0,88 mm³ (2 mm-Gruppe), bzw. 2,88±0,28 mm³ (3 mm-Gruppe). Die mittlere Defektgröße verringerte sich entsprechend um 77,6% (1 mm-Gruppe), 56,8% (2 mm-Gruppe), bzw. 28,6% (3 mm-Gruppe). Die histomorphologischen, histomorphometrischen und immunhistochemischen Analysen zeigten keine statistisch signifikanten Unterschiede zwischen den drei experimentellen Gruppen. Das verwendete MouseExFix-System ist ein zuverlässiges und einfach zu handhabendes Verfahren zur Stabilisierung eines kritischen segmentalen Knochendefekts an der immundefizienten Maus, wenn ein 3 mm-Defekt erzeugt wird. Das im Rahmen der Studie entwickelte und validierte murine extern stabilisierte, segmentale kritische Knochendefektmodell ermöglicht die präklinische Evaluierung von Konzepten zur lokalen Knochenregeneration inklusive der Verwendung allo- und xenogener Zellen. / The development of innovative therapies for bone regeneration requires the use of advanced site-specific bone defect small animal models. In this context, murine models are of major importance as they allow for sufficient sample sizes prior to preclinical testing using larger animals. Owing to the small dimensions of the murine femur only a few custom fabricated fixation devices have been described in the literature so far. The aim of this investigation was to develop and validate a new, externally fixated critical size bone defect model for immunodeficient mice. Thirty male nu/nu mice (40.7 ± 2.8 g, 95 ± 2.6 days old) were anesthetized by isoflurane inhalation and an external fixation device (MouseExFix, RISystem, AO Research Institute Davos, Switzerland) was attached to the right femur. Femoral bone defects of 1 mm (n=10), 2 mm (n=10) and 3 mm (n=10) were created. Wounds were closed without any additional treatment. X-ray films obtained immediately after surgery and every 2 weeks postoperatively during the 12 week postoperative observation period were evaluated for bony regeneration and fusion. Furthermore, histomorphology, histomorphometry, immunohistochemistry and µCT analysis were performed. All of the animals survived the operation. Twenty four out of 30 animals reached the twelfth postoperative week. µCT analyses after twelve weeks showed that 3/8 of the 1 mm defects, 5/8 of the 2 mm defects and 8/8 of the 3 mm defects remained as nonunions. The defect volume was 0.36 ± 0.42 mm³ (1 mm group), 1.40 ± 0.88 mm³ (2 mm group), and 2.88 ± 0.28 mm³ (3 mm group) (p<0.001, between all groups). The defect size decreased by 77.6% (1-mm group), 56.8% (2-mm group) and 28.6% (3-mm group) (p=0.152, between all groups). Our method using the MouseExFix device has proven to be a reliable and easy-to-handle external fixation system for the stabilization of critical-size segmental bone defects in immundeficient mice when 3 mm defects are generated. This mouse model allows for high-throughput translational evaluation of concepts for site-specific bone regeneration including strategies using allogenic and xenogenic cell types.

Defect prevention (DP) in early stages of software development life cycle (SDLC) is very cost effective than in later stages. The requirements elicitation and analysis &amp; negotiation (E and A&amp;N) phases in requirements engineering (RE) process are very critical and are major source of requirements defects. A poor E and A&amp;N process may lead to a software requirements specifications (SRS) full of defects like missing, ambiguous, inconsistent, misunderstood, and incomplete requirements. If these defects are identified and fixed in later stages of SDLC then they could cause major rework by spending extra cost and effort. Organizations are spending about half of their total project budget on avoidable rework and majority of defects originate from RE activities. This study is an attempt to prevent requirements level defects from penetrates into later stages of SDLC. For this purpose empirical and literature studies are presented in this thesis. The empirical study is carried out with the help of six companies from Pakistan &amp; Sweden by conducting interviews and literature study is done by using literature reviews. This study explores the most common requirements defect types, their reasons, severity level of defects (i.e. major or minor), DP techniques (DPTs) &amp; methods, defect identification techniques that have been using in software development industry and problems in these DPTs. This study also describes possible major differences between Swedish and Pakistani software companies in terms of defect types and rate of defects originating from E and A&amp;N phases. On the bases of study results, some solutions have been proposed to prevent requirements defects during the RE process. In this way we can minimize defects originating from E and A&amp;N phases of RE in the bespoke requirements engineering (BESRE).