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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

A Concurrency and Time Centered Framework for Certification of Autonomous Space Systems

Dechev, Damian 2009 December 1900 (has links)
Future space missions, such as Mars Science Laboratory, suggest the engineering of some of the most complex man-rated autonomous software systems. The present process-oriented certification methodologies are becoming prohibitively expensive and do not reach the level of detail of providing guidelines for the development and validation of concurrent software. Time and concurrency are the most critical notions in an autonomous space system. In this work we present the design and implementation of the first concurrency and time centered framework for product-oriented software certification of autonomous space systems. To achieve fast and reliable concurrent interactions, we define and apply the notion of Semantically Enhanced Containers (SEC). SECs are data structures that are designed to provide the flexibility and usability of the popular ISO C++ STL containers, while at the same time they are hand-crafted to guarantee domain-specific policies, such as conformance to a given concurrency model. The application of nonblocking programming techniques is critical to the implementation of our SEC containers. Lock-free algorithms help avoid the hazards of deadlock, livelock, and priority inversion, and at the same time deliver fast and scalable performance. Practical lock-free algorithms are notoriously difficult to design and implement and pose a number of hard problems such as ABA avoidance, high complexity, portability, and meeting the linearizability correctness requirements. This dissertation presents the design of the first lock-free dynamically resizable array. Our approach o ers a set of practical, portable, lock-free, and linearizable STL vector operations and a fast and space effcient implementation when compared to the alternative lock- and STM-based techniques. Currently, the literature does not offer an explicit analysis of the ABA problem, its relation to the most commonly applied nonblocking programming techniques, and the possibilities for its detection and avoidance. Eliminating the hazards of ABA is left to the ingenuity of the software designer. We present a generic and practical solution to the fundamental ABA problem for lock-free descriptor-based designs. To enable our SEC container with the property of validating domain-specific invariants, we present Basic Query, our expression template-based library for statically extracting semantic information from C++ source code. The use of static analysis allows for a far more efficient implementation of our nonblocking containers than would have been otherwise possible when relying on the traditional run-time based techniques. Shared data in a real-time cyber-physical system can often be polymorphic (as is the case with a number of components part of the Mission Data System's Data Management Services). The use of dynamic cast is important in the design of autonomous real-time systems since the operation allows for a direct representation of the management and behavior of polymorphic data. To allow for the application of dynamic cast in mission critical code, we validate and improve a methodology for constant-time dynamic cast that shifts the complexity of the operation to the compiler's static checker. In a case study that demonstrates the applicability of the programming and validation techniques of our certification framework, we show the process of verification and semantic parallelization of the Mission Data System's (MDS) Goal Networks. MDS provides an experimental platform for testing and development of autonomous real-time flight applications.
122

Επίδραση των πολυαμινών στη δομή και λειτουργία του 5s ριβοσωματικού RNA

Γερμπανάς, Γεώργιος 30 July 2007 (has links)
Η ΒΥΠ διαθέτει αντίτυπο της διατριβής σε έντυπη μορφή στο βιβλιοστάσιο διδακτορικών διατριβών που βρίσκεται στο ισόγειο του κτιρίου της. / Στα βακτήρια, η μεγάλη ριβοσωματική υπομονάδα αποτελείται από δύο είδη RNA, το 23S και το 5S rRNA, καθώς και 33 πρωτεΐνες. Ο σχηματισμός του πεπτιδικού δεσμού και η απελευθέρωση της πεπτιδικής αλυσίδας επιτελούνται στη μεγάλη υπομονάδα, όπου εδράζεται το καταλυτικό κέντρο της πεπτιδυλοτρανσφεράσης (PTase). Εκτός αυτού, η μεγάλη υπομονάδα περιλαμβάνει το κέντρο προσδέσεως των μεταφραστικών παραγόντων, το οποίο πυροδοτεί τη GTPase δραστηριότητα των G-πρωτεϊνικών παραγόντων, που εμπλέκονται στη μετατόπιση των υποστρωμάτων και άλλες ριβοσωματικές λειτουργίες. Έχει υποτεθεί ότι το 5S rRNA παίζει ουσιώδη ρόλο στη συγκρότηση του κέντρου της PTase και στη μετάδοση σημάτων μεταξύ του καταλυτικού κέντρου και των ριβοσωματικών συστατικών που διεκπεραιώνουν τη μετατόπιση των υποστρωμάτων. Το ιοντικό περιβάλλον φαίνεται να επηρεάζει καθοριστικά τη διαμόρφωση του 5S rRNA. Για παράδειγμα, έχει βρεθεί ότι οι πολυαμίνες δεσμεύονται εκλεκτικά στο 5S rRNA και επηρεάζουν τη δραστικότητα του έναντι του διμεθυλο-θεϊκού, ενός αντιδραστηρίου-ιχνηθέτη της τριτοταγούς δομής του RNA. Αρχικά ελέγξαμε αν υπάρχουν εξειδικευμένες θέσεις πρόσδεσης των πολυαμινών στο 5S rRNA. Στη συνέχεια, με σκοπό να ελέγξουμε αν η πρόσδεση των πολυαμινών επηρεάζει τη λειτουργία του 5S rRNA, 70S ριβοσώματα προγραμματισμένα με πολύ-ουριδυλικό σχηματίσθηκαν από 50S υπομονάδες, ολικά ή εκλεκτικά φωτοσημασμένες με ένα φωτοδραστικό ανάλογο της σπερμίνης και από 30S ακατέργαστες υπομονάδες. Αυτά τα ριβοσώματα είχαν την ικανότητα να δεσμεύουν AcPhe-tRNA ελαφρώς ισχυρότερα, σε σύγκριση με ριβοσώματα συγκροτημένα από φυσικά συστατικά, μη περιέχοντα πολυαμίνες. Το γεγονός αυτό υποδηλώνει ότι η πρόσδεση πολυαμινών στο 5S rRNA επηρεάζει, σε μικρό βαθμό, τη λειτουργία του παράγοντα επιμήκυνσης EF-Tu. Συζευγμένα, όμως, τα εν λόγω ριβοσώματα με tRNAPhe στην Ε-θέση και AcPhe-tRNAστην Ρ-θέση, επέδειξαν ισχυρότερη καταλυτική δραστικότητα και αυξημένη ικανότητα για μετατόπιση των υποστρωμάτων. Τα αποτελέσματα αυτά εισηγούνται σημαντική εμπλοκή των πολυαμινών στο λειτουργικό ρόλο του 5S rRNA κατά την κατάλυση και μετατόπιση των υποστρωμάτων. / In bacteria, the large ribosomal subunit comprises two RNA species, 23S and 5S rRNA, and 33 proteins. Peptide bond formation and peptide release are catalyzed by the large subunit, where the peptidyltransferase (PTase) center is located. In addition to this center, which triggers the GTPase activities of G-protein factors involved in translocation and other ribosomal functions. It has been hypothesized that 5S rRNA plays essential role in assembling the PTase center and mediating signal transmissions between this center and the translocation machinery. Furthermore, the ionic environment seems to affect the conformation of 5S rRNA. For instance, polyamines have been found to bind specifically to 5S rRNA and influence the 5S rRNA reactivity towards dimethyl-sulfate (DMS), a chemical probe of RNA tertiary structure. Initially we examined whether there are specific sites for binding of polyamines. To test whether the binding of polyamines influence the function of 5S rRNA poly(U)-programmed 70S ribosomes were reconstituted from 50S subunits, totally or specifically photolabelled in their 5S rRNA with a photoreactive analogue of spermine, and native 30S subunits. These ribosomes were found to enzymatically bind AcPhe-tRNA better than ribosomes reconstituted from native components. This means, that furnishing 5S rRNA with spermine slightly influences the elongation factor EF-Tu function. However, equipped with tRNAPhe at the A-site and AcPhe-tRNA at the P-site, these ribosomes exhibited higher catalytic activity and enhanced tRNA translocation efficiency. These results suggest an essential impact of polyamines on the functional role of 5S rRNA in catalysis and translocation of translation substrates.
123

Using Computer-Aided Personalized System of Instruction (CAPSI) to teach Discrete-Trials Teaching (DTT) for educating children with Autism Spectrum Disorders (ASDs)

Zaragoza Scherman, Alejandra 10 September 2010 (has links)
The present study evaluated the use of a self-instructional manual supported by a computer-aided personalized system of instruction (CAPSI) for teaching Discrete-Trials Teaching (DTT) to university students. Prior to studying the manual, five participants taught three tasks, commonly taught to children with Autism Spectrum Disorders (ASD), to a confederate role-playing a child with an ASD. Using the Discrete-Trials Teaching Evaluation Form (DTTEF), the main researcher assessed the participants’ ability to perform DTT accurately. Subsequently, participants studied a self-instructional manual using CAPSI to demonstrate mastery of study questions about DTT. Finally, participants once again attempted to teach the three tasks to a confederate role-playing a child with an ASD. Overall mean baseline accuracy on the DTTEF was 54.86%, and improved to 84.73% in post-treatment, a 30% improvement. Participants’ self-recorded study time was an average of 12 hours and 48 minutes. The results suggest that CAPSI is an effective educational tool for the delivery of the self-instructional manual. Future research should investigate (1) how to make CAPSI even more effective, and (2) whether these results can be generalized to other populations such as ABA tutors, parents, and paraprofessionals working with children with ASD.
124

Mechanisms of dormancy, preharvest sprouting tolerance and how they are influenced by the environment during grain filling and maturation in wheat (Triticum aestivum L.)

Biddulph, Thomas Benjamin January 2007 (has links)
[Truncated abstract] Wheat is the main crop in Australia and there are stringent quality requirements. Preharvest sprouting induced by rainfall between maturity and harvest lowers grain quality from premium to feed grades and reduces yield. Wheat production has expanded into the southern Western Australian region where preharvest sprouting occurs in ~1 in 4 seasons and development of more preharvest sprouting tolerant genotypes is required. The main mechanism for improving preharvest sprouting tolerance is grain dormancy. There is genetic variation for dormancy based in the embryo and seed coat but dormancy is complex and is influenced by environmental conditions during grain filling and maturation. Screening and selecting for preharvest sprouting tolerance is problematic and the level of tolerance needed for regions which differ in the level of dormancy they impose, requires clarification. The research presented here aims to answer the underlying question for breeders of how much dormancy is required for preharvest sprouting tolerance in contrasting target environments of the central and coastal wheat belt regions of Western Australia. In the central and coastal wheat belt regions, field trials with modified environments were used to determine the environmental influence on dormancy. Water supply (without directly wetting the grain) and air temperature were modified during grain development in a range of genotypes with different mechanisms of dormancy to determine the influence of environment on dormancy. ... Genotypes with embryo dormancy were consistently the most preharvest sprouting tolerant, even though this dormancy was influenced by the environmental conditions in the different seasons. Pyramiding the embryo component with the specific seed coat component and/or awnless head trait removed some of the environmental variation in preharvest sprouting tolerance, but this was generally considered excessive to the environmental requirements. The methods developed here, of field imposed stresses may provide a valuable tool to further understand the influence of environment on the regulation of dormancy, as different phenotypes can be made with the same genotype. Moisture stress, sudden changes in water supply or high temperatures during the late dough stages influenced dormancy phenotype and should be considered and avoided if possible when selecting locations and running trials for screening for genetic differences in preharvest sprouting tolerance. In the Western Australian context, the embryo component of dormancy appeared to be sufficient and should be adopted as the most important trait for breeding for preharvest sprouting tolerance.
125

Immunoneutralization Of Cytotoxic Abrin : Insights Into Mechanisms And Therapy

Bagaria, Shradha 07 1900 (has links) (PDF)
Type II Ribosome Inactivating Proteins (RIPs), commonly known as A/B toxins are heterodimers comprising of a catalytically active A chain, an RNA N-glycosidase which inhibits protein synthesis and a lectin-like B chain required for the binding of the toxin to the cell surface and internalization of the same. Abrin is a type II RIP obtained from the mature seeds of Abrus precatorius plant that is extremely toxic and has been shown to be 75 times more potent than its well studied sister toxin, ricin. The LD50 dose for abrin is only 2.8 µg/kg body weight of mice and its potential use in bio-warfare is a cause of major concern. Abrin has been classified as a select agent by the Centre for Disease Control and Prevention, U.S.A., because it is stable, effective at very low concentrations and easy to purify and disseminate in large amounts. In spite of abrin being a potential bio-warfare agent, there is no antidote or vaccine available against this toxin till date. The first and only neutralizing monoclonal antibody (mAb) against abrin, namely D6F10, was reported from our laboratory and has been shown to rescue toxicity of abrin in cells as well as in mice. The study reported in the thesis focuses on understanding the mechanism of neutralization of abrin by the mAb D6F10 and development of a potential vaccine candidate against the toxin. In order to map the epitope corresponding to the antibody, first, overlapping gene deletion constructs spanning the entire length, 251 amino acids, of ABA were generated and checked for binding to the mAb. Fragments shorter than 1-175 did not show immuoreactivity. Analysis of the crystal structure of abrin A chain revealed that a helix spanning the amino acids 148-167 was present at the core of the protein structure and truncation in this region of the protein possibly results in loss of conformation leading to abrogation of antibody binding. Therefore, a novel strategy of epitope mapping was adopted. Abrus precatorius agglutinin (APA) is a homologue of abrin obtained from the same plant source. The A chains of abrin and APA share 67% sequence identity and their crystal structures superimpose very well but unlike abrin the APA A chain does not bind the mAb D6F10. Chimeric constructs were generated within the region 1-175 of A chains of both ABA and APA and deletions and mutations of the ABA was then made on the APA as scaffold. It could be concluded that the amino acids of the region 75¬123 are involved in the formation of the epitope. Further, based on sequence alignment of ABA and APA A chain 13 residues in the chimera ABA1-123APA124-175 were mutated and it was found that the mutation of the residues Thr 112, Gly 114 and Arg 118 resulted in loss of binding to the antibody. Furthermore, the mAb D6F10 rescues inhibition of protein synthesis by abrin in HeLa cells by internalizing in cells along with abrin and possibly occluding the active site cleft of ABA. The antibody prevents cell attachment of abrin at higher concentrations. The observations provide novel insights into mechanisms of many known neutralizing antibodies against A/B toxins. The study also highlights that chimeric protein constructs could possibly be developed as potential vaccine candidates for neutralization of abrin intoxication.
126

Occupational Stress, Burnout and Teacher efficacy in teachers, special educators and habilitation professionals with and without formal ABA training / Yrkesstress, utbrändhet och Teacher efficacy (lärareffektivitet) hos lärare, specialpedagoger och habiliteringspersonal med och utan formell TBA-utbildning

Lundin, Fredrik January 2021 (has links)
Research suggests a correlation between high levels of stress and burnout, and low levels of self- efficacy, in school and habilitation professionals. These findings are also prominent in practitioners in Applied Behavior Analysis (ABA) such as teachers, psychologists and Board-Certified Behavior Analysts (BCBAs). This current study aimed to examine the levels in self-reported stress, burnout, and self-efficacy reported in the Ohio State Teacher Efficacy Scale (OSTES), in a Swedish-speaking sample consisting of sixty-seven participants based in school settings, and twenty-five participants based in habilitation settings. All participants were divided into two subgroups: one group who have stated participation in formal post-graduate ABA-training (n = 31), and a group without formal ABA training (n = 61). The hypotheses formulated from previous research were: 1) Teacher Efficacy levels are higher in professionals with ABA-training; 2) Stress-levels are lower in professionals with ABA- training; 3) Burnout levels are lower in professionals with ABA-training; 4) Stress-levels are lower in professionals working in habilitation settings; 5) Burnout levels are lower in professionals working in habilitation settings. Analyzes showed that stress correlated highly positive with burnout, and that teacher efficacy had a negative correlation with stress and burnout. Furthermore, no differences in stress and burnout levels were found between participants from school and habilitation, but the levels in Self-reported Stress and Self-reported Burnout were lower in the ABA group, which therefore confirmed the predictions. Reported OSTES-levels were higher in the ABA-group, but at non- significant levels (except in the sub-item “Efficacy for instructional strategies” where significant levels were found). The conclusion was that educators high in teacher efficacy may be less likely to suffer from stress and burnout, than low-efficacy educators. To address the growing problem of stress-related diseases among Swedish school and habilitation staff, the current teacher efficacy-levels in these occupations must be further highlighted. / Forskning tyder på en korrelation mellan höga nivåer av stress och utbrändhet, och låga nivåer av self- efficacy hos personal i skola och habilitering. Dessa forskningsresultat är också framträdande gällande utövare av tillämpad beteendeanalys (TBA), såsom lärare, psykologer och certifierade beteendeanalytiker (BCBA). Den aktuella studien syftade till att undersöka nivåerna i självrapporterad stress, utbrändhet och self-efficacy baserat på Teacher efficacy-skalan Ohio State Teacher Efficacy Scale (OSTES), gällande ett urval av svensktalande deltagare bestående av sextiosju personer som arbetar inom skolan och tjugofem personer som arbetar inom habiliteringen. Samtliga deltagare delades in i två undergrupper: en grupp som tidigare genomfört en formell TBA-utbildning (n = 31) och en grupp utan formell TBA-utbildning (n = 61). Hypoteserna utifrån tidigare forskning var: 1) Teacher efficacy-nivåerna är högre hos yrkesverksamma med TBA-utbildning; 2) Stressnivåerna är lägre hos professionella med TBA-utbildning; 3) Utbrändhetsnivåerna är lägre hos professionella med TBA-utbildning; 4) Stressnivåerna är lägre hos yrkesverksamma som arbetar inom habiliteringsyrken; 5) Utbrändhetsnivåerna är lägre hos professionella som arbetar inom habiliteringsyrken. Analyserna visade att stress korrelerade mycket positivt med utbrändhet och att Teacher efficacy-nivåerna hade en negativ korrelation med stress och utbrändhet. Vidare hittades inga skillnader i stress- och utbrändhetsnivåerna mellan deltagare från skola och habilitering, men nivåerna i självrapporterad stress och självrapporterad utbrändhet var lägre i TBA-gruppen, vilket därför bekräftade denna förutsägelse. Nivåerna erhållna i OSTES-skalan var högre i TBA-gruppen, men på icke-signifikanta nivåer (förutom i underkategorin “Efficacy for instructional strategies” där signifikanta nivåer hittades). Slutsatsen var att lärare med hög Teacher efficacy kan vara mindre benägna att drabbas av stress och utbrändhet än lärare med låg Teacher efficacy. För att ta itu med det växande problemet med stressrelaterade sjukdomar bland svensk skol- och habiliteringspersonal måste de aktuella nivåerna av Teacher efficacy i dessa yrken belysas ytterligare.
127

The Use of School-Wide Positive Behavior Support at a Rural High School to Decrease Disruptive Behavior for Both Typical Students and Students Identified with Special Needs.

Blevins, Leia Dowdy 15 December 2007 (has links) (PDF)
There is ever-increasing pressure on school officials to provide a safe school environment that is conducive to learning. There is also a growing concern from teachers and administrators that many students are unrecognized for their continual appropriate behavior(s), in part, because of the attention consumed by both challenging students and students with exceptional talents and abilities. In response, a School-Wide Positive Behavior Support (SWPBS) approach is growing in popularity to address both of these issues. SWPBS is implemented across an entire school population and involves all individuals whether they are challenging, exceptional, or typical. The initial research shows encouraging results and supports the effectiveness of a School-Wide Positive Behavior Support program. This study focused on the development, implementation, and results of a SWPBS program at a rural high school. Data collected included office daily referrals, suspensions, expulsions, attendance, and the number of reinforcers (Mo-Bucks) distributed by staff. Outcome data indicated that compared to the year prior to the SWPBS program's implementation, there was a reduction in office daily referrals, a reduction in expulsions, and an increase in attendance. The results of this 3-year study supported the effectiveness of SWPBS as an intervention for reducing disruptive behaviors at the high school level for typical students as well as for students with special needs.
128

Reported Use of Equivalence-Based Instruction Among Practicing Behavior Analysts

North, Cody 14 December 2022 (has links)
No description available.
129

Autism Education and Early Intervention: What Experts Recommend and How Parents and Public Schools Provide

Reffert, Lori A. 10 June 2008 (has links)
No description available.
130

Análisis funcional del gen OCP3

Ramirez Garcia, Vicente 19 May 2009 (has links)
El gen OCP3 codifica un factor de transcripción de la familia Homeobox. En trabajos anteriores se ha demostrado que la pérdida de función de este gen en Arabidopsis thaliana causa un notable incremento de la resistencia a infecciones por hongos necrotrofos como Botrytis cinerea o Plectosphaerella cucumerina. Además esa resistencia es dependiente de la correcta señalización mediada por ácido jasmónico (JA), una de las fitohormonas más ampliamente relacionadas con el establecimiento de las respuestas defensivas en plantas junto con el ácido salicílico (SA). A través del balance entre las señalizaciones de estos dos reguladores (JA y SA), la planta es capaz de disparar la respuesta defensiva más apropiada dependiendo del tipo de patógeno que la ataca. Así pues, el estudio de las interrelaciones entre JA y SA y los componentes que transducen las respectivas señales es de gran utilidad para desentramar la compleja red de regulación que compone la respuesta inmune de las plantas. Mediante el estudio de dobles mutantes, se ha demostrado un nuevo papel de OCP3 en la interconexión entre SA y JA en respuesta a Pseudomonas syringae e Hyaloperonospora arabidopsidis, dos patógenos de tipo biotrofo. Además se propone a OCP3 como un nuevo componente de la denominada Resistencia Sistémica Inducida (ISR). Existe cierto grado de solapamiento entre las respuestas de las plantas frente a estreses bióticos y abióticos. La identificación de los componentes comunes a estas dos rutas es de gran valor para conocer cómo las plantas se adaptan ante situaciones de estrés diferentes. Mediante un rastreo por doble híbrido en levadura, se identificaron cuatro proteínas que interaccionan con OCP3. Todas ellas están implicadas en la señalización mediada por ABA, una fitohormona que regula, entre otros procesos, la respuesta frente al estrés hídrico. En el presente trabajo se aportan numerosas evidencias que indican que OCP3 regula el cierre estomático promovido por ABA, y con ello la tolerancia a / Ramirez Garcia, V. (2008). Análisis funcional del gen OCP3 [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4683

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