published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Η οικογένεια Tephritidae των Διπτέρων εντόμων περιλαμβάνει είδη με μεγάλη οικονομική σημασία. Τα περισσότερα αποτελούν σημαντικά παράσιτα γεωργικών καλλιεργειών προκαλώντας μεγάλες καταστροφές στην παραγωγή φρούτων και λαχανικών παγκοσμίως. Τα σημαντικότερα παράσιτα ανήκουν στα γένη Anastrepha, Bactrocera, Ceratitis, Dacus και Rhagoletis. Η μελέτη των ειδών αυτών στο επίπεδο της γενετικής και της μοριακής βιολογίας θα μπορούσε να συμβάλλει σημαντικά στην ανάπτυξη μεθόδων βιολογικού ελέγχου των πληθυσμών τους. Με εξαίρεση τη Μεσογειακή μύγα, Ceratitis capitata, που θεωρείται ο καλύτερα μελετημένος οργανισμός της οικογένειας, η πληροφορία για άλλα είδη είναι πολύ περιορισμένη. Στη παρούσα μελέτη εξετάσθηκε η πιθανότητα δια-ειδικής ενίσχυσης μικροδορυφορικών δεικτών που αναπτύχθηκαν στο εργαστήριό μας για τη Μεσογειακή μύγα σε είδη των γενών Anastrephα, Bactrocera και Rhagoletis καθώς και στο είδος C. fasciventris με κύριο στόχο την ανάπτυξη κατάλληλων γενετικών δεικτών που θα μπορούσαν να χρησιμοποιηθούν σε γενετικές ή και πληθυσμιακές μελέτες των ειδών αυτών. Από τους 102 μικροδορυφορικούς δείκτες που αναλύθηκαν μέσω της PCR, οι 31 (31%) έδωσαν δια-ειδική ενίσχυση σε τουλάχιστον ένα από τα εξεταζόμενα είδη έκτος του γένους Ceratitis. Το αντίστοιχο ποσοστό για την C. fasciventris ήταν 67,75%. Το μέγεθος των προϊόντων αυτών ήταν παρόμοιο ή και ταυτόσημο με το αναμενόμενο στη Μεσογειακή μύγα. Τα αποτελέσματα από την αλληλούχιση των προϊόντων PCR και τη σύγκριση τους με τις αντίστοιχες περιοχές της Μεσογειακής Μύγας δείχνουν ότι η δομή των μικροδορυφορικών μοτίβων αλλά και των μοναδικών περιοχών που τους περιβάλλουν φαίνεται να διατηρείται στη πλειοψηφία των περιπτώσεων για τη C. fasciventris. Σε όλες τις περιπτώσεις που εξετάσθηκαν βρέθηκαν επαναλαμβανόμενα μοτίβα. Η συγκριτική ανάλυση των αλληλουχιών αυτών μπορεί να προσφέρει πολύτιμους γενετικούς δείκτες για τα είδη αυτά αλλά και πληροφορίες για τις φυλογενετικές τους σχέσεις. / Tephritidae family of Diptera includes species of great economical importance. Most of them are significant parasites of agriculture causing severe damages by attacking fruits and vegetables world wide.The most important pests belong to the genera Anastrepha, Bactrocera, Ceratitis, Dacus and Rhagoletis. Studies of these species on genetic and molecular level could contribute significantly to the development of methods for their biological control. Except for the Mediterranean fruit fly, Ceratitis capitata, which is the best understood fruit fly pest at the genetic/molecular level, limited information exists for other species. In the present work we examined the possibility of cross-species amplification of microsatellite markers that were developed in our laboratory for C. capitata. Cross-species analyses were performed on species belonging to the genera Anastrepha, Bactrocera and Rhagoletis as well as C. fasciventris, aiming at the development of suitable markers that could be used in genetic and/or population studies of these species. A total of 102 microsatellites markers were examined through PCR. Thirty one of them (31%) showed cross-species amplification in at least one of the analyzed species. The percentage for C. fasciventris was 67.75%. The majority of the products were similar or identical in size to those expected in C. capitata. Sequencing analyses of the PCR products are when compared to the Medfly markers demonstrate that the structures of the repeat motifs and their flanking sequences are maintained in most studied cases that involve C. fasciventris. In every case studied repeat motifs were found. This analysis can provide not only useful genetic markers for the analyzed species but also information for their phylogenetic relationships.

This dissertation uses qualitative research methods to describe the history of language use and maintenance on the islands of Aruba and Puerto Rico. More specifically, it examines how the islands' unique colonial circumstances have affected the maintenance of the local language. The multidisciplinary field of language planning and policy (LPP) has historically focused on documenting, categorizing and revitalizing languages that have undergone significant language shift. As a result, the majority of the discourse regarding threatened languages also implies that a threatened language will soon be endangered. The language contexts on the islands of Aruba and Puerto Rico do not conform to this often assumed linear progression. The use of document analysis, interviews with key players in LPP and observations on both islands provide the data for the position that there are unique contexts where language threat can be discussed, not in terms of language shift, but in terms of perceptions of threat. In addition to providing a detailed historical account of language situations on both islands, this dissertation frames the findings within a larger framework of redefining language threat. Special attention is paid to how social agents have influenced perceptions through the social amplification of risk framework. The work concludes with an argument for a framework that incorporates not only languages that have witnessed language shift, but also language contexts where languages are perceived to be threatened, with the understanding that such a distinction could potentially move the field of LPP toward a better understanding of language maintenance.

Vaccines directed against the influenza virus become ineffective due to continuous mutation. An alternative approach might be to control replication at the genomic level by enzymatic methylation of the polymerase genes. Hence in this study, a method to locate and successfully isolate the H1N1 influenza A polymerase genes was investigated. The virus was cultured in chick embryos via the allantoic route using aseptic techniques. Following incubation, the allantoic fluid was isolated and washed to remove any contaminating blood cells. The allantoic fluid was checked for fungal and bacterial contamination using the blood agar test and the presence of the virus was established by the haemagglutination titration test. Viral particles were pelleted by ultracentrifugation. Electron microscopy verified the morphology and size of these viruses while immunofluorescence studies, using a monoclonal antibody, confirmed the influenza A strain. The ribose test verified the presence of RNA in the samples. Purified viral pellets were pooled and homogenised in buffer containing guanidine thiocyanate, mercaptoethanol and sarkosyl. The samples were incubated on ice before mechanical disruption of the virus. Viral RNA was isolated from the upper aqueous layer after a standard phenol/chloroform extraction procedure. RNA was quantified spectrophotometrically and purity assessed initially by the absorbance ratio readings at 260/280 nm. Electrophoresis of the RNA samples was performed together with RNA molecular weight markers on a 1.5% formamide agarose gel. Five bands were identified and the band containing the polymerase genes was size selected, located and excised. Purification of the polymerase genes from the agarose was achieved by using the BIO 101 RNAid kit. The three isolated polymerase RNAs were reverse transcribed using the Boehringer Mannheim cDNA synthesis kit. The results indicate that the H1N1 influenza virus was successfully grown and isolated from chick embryos. Absence of contamination and verification of viral presence at different stages of the study were indications that asepsis was successfully achieved. The RNA obtained was sufficient and suitable for cDNA synthesis. This cDNA may now be used for further molecular analysis and subsequent DNA methylation studies. Further, transfection studies may then be performed to determine, if any, the the expression of methylated and unmethylated cDNA. / Thesis (M.Med.)-University of Natal, 1992.

Experiments were conducted in a recirculating water channel to determine the flow topology around a simplified two-wheel landing gear model. Both hydrogen bubble visualization and Particle Image Velocimetry techniques were employed. The Reynolds number based on wheel diameter was 32,500. The general flow topology was characterized for several wheel configurations. Previously undiscovered structures have been found in several regions of the flow field, and their behavior was found to depend strongly on the geometry of the wheels. The phenomena of vorticity amplification near the stagnation point of the wheels was also studied. Weak upstream vorticity was found to collect, grow, and amplify into large coherent structures which then shed in a regular manner. The size, location, and shedding frequency of these structures has been characterized. The impingement point of the upstream vorticity was found to dictate the dynamics of the phenomena.

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Experiments were conducted in a recirculating water channel to determine the flow topology around a simplified two-wheel landing gear model. Both hydrogen bubble visualization and Particle Image Velocimetry techniques were employed. The Reynolds number based on wheel diameter was 32,500. The general flow topology was characterized for several wheel configurations. Previously undiscovered structures have been found in several regions of the flow field, and their behavior was found to depend strongly on the geometry of the wheels. The phenomena of vorticity amplification near the stagnation point of the wheels was also studied. Weak upstream vorticity was found to collect, grow, and amplify into large coherent structures which then shed in a regular manner. The size, location, and shedding frequency of these structures has been characterized. The impingement point of the upstream vorticity was found to dictate the dynamics of the phenomena.

Rapidly developing areas of high field physics, generation of high order harmonics or isolated attosecond pulses, require high peak power few-cycle pulse sources. Optical parametric chirped pulse amplification (OPCPA) has shown potential to satisfy these requirements and at present OPCPA is the leading technology for high energy few-cycle pulse table-top systems. The main objectives of this thesis were to investigate optical parametric amplification of broadband seed pulses in femtosecond and picosecond regimes, to develop and optimize a compact TW-scale OPCPA system intended for various applications in areas of high-field physics. In this thesis the main concept of such system is discussed, advantages and disadvantages of proposed approach are analyzed, the setup is compared to other world known systems. In this thesis an original approach for power scaling of regenerative amplifier by implementing several active elements in prolonged resonator has been proposed and investigated. Femtosecond pulse amplification in dual active element Yb:KGW regenerative amplifier has been demonstrated, resulting in boost of average output power to 30 W. Broad bandwidth pulse generation, parametric amplification and compression to transform limited values were analyzed both numerically and experimentally. White light continuum generation in bulk material for broadband seed formation, its further optical parametric amplification in noncollinear scheme were investigated and Yb:KGW driven... [to full text] / Stiprių laukų fizikos srities tyrimams, aukštų eilių harmonikų ir pavienių atosekundinių impulsų generavimui, yra reikalingos kompaktiškos teravatų smailinės galios kelių optinių ciklų išvadinių impulsų lazerinės sistemos. Optinis parametrinis „čirpuotų“ impulsų stiprinimas yra vienas pagrindinių metodų leidžiančiu pasiekti šiems taikymams reikalingus lazerinių sistemų parametrus. Šios disertacijos darbo tikslas – ištirti femtosekundinės ir pikosekundinės trukmės impulsų stiprinimą optiniuose parametriniuose stiprintuvuose užkratui naudojant ypač plataus spektro signalą, bei sukurti ir optimizuoti čirpuotų impulsų parametrinio stiprinimo sistemą, užtikrinančią patikimą teravatų smailinės galios impulsų formavimą. Disertacijoje aptariama bendra tokios sistemos architektūra, nagrinėjami privalumai ir trūkumai, palyginama su kitomis pasaulyje egzistuojančiomis sistemomis. Šiame darbe pasiūlytas ir ištirtas lazerių vidutinės išvadinės galios didinimo metodas, naudojant kelis aktyviuosius elementus viename rezonatoriuje, ir pademonstruotas femtosekundinių impulsų stiprinimas šio metodo pagrindu sukonstruotame dviejų Yb:KGW aktyvių elementų regeneratyviniame stiprintuve, tokiu būdu padidinant lazerio išvadinę galią iki 30 W. Darbo metu sukonstruota bei ištirta Yb:KGW femtosekundiniu lazeriu kaupinamos baltos šviesos kontinuumo generavimo ir nekolinearaus kaupinimo optinio parametrinio stiprinimo sistema, kurios išvadinių impulsų energiją siekia 20 mikrodžiaulių, o impulsai... [toliau žr. visą tekstą]

A clinically-focused music appreciation training program (MATP) was developed for use by recipients of cochlear implants (CI) and wearers of hearing aids (HA). It aimed to enhance listeners’ music appreciation abilities, with a specific focus on timbre and musical style. The MATP was pilot-tested on 17 adult postlingually deafened CI recipients (8 female, 9 male, mean age = 60.2 years) and 13 adult HA users (7 female, 4 male, mean age = 63.9 years), with each device group divided into a control and a training group. The training groups were asked to use the MATP for 30 minutes per day four times a week for 10 weeks. The control groups were asked to continue with their normal listening habits for the same time period. Both the training and control groups were assessed on tests of instrument, ensemble and style identification as well as pleasantness ratings of musical excerpts, before and after the 10-week period. Participants in the training groups also completed a program evaluation questionnaire at the end of the training period. The results showed that the training program significantly improved the quality ratings of CI recipients for ensemble stimuli (p = .034). There were, however, no significant improvements for CI users on the timbre discrimination tasks or quality ratings for single instruments, nor were there any significant improvements for the HA users on any of the discrimination tasks or in their quality ratings. The findings suggest that CI recipients’ quality appraisal can be improved through training, independent of perceptual accuracy. On evaluating the program, the majority of CI and HA trainees reported that the MATP was enjoyable and beneficial in terms of music appreciation. Future directions for continued development of the MATP and testing of its efficacy are discussed.