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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.
71

Synthesis of [1-3H]-Geranylgeranyl Pyrophosphate and its Incubation with Taxus x Media Densiformis

MacEachern, Gerri Jacqueline 04 1900 (has links)
<p> Recently, the discovery that taxol (2), a highly modified diterpenoid available from Taxus species, possesses anticancer activity has attracted considerable interest. The synthesis of [1-3H]-geranylgeranyl pyrophosphate(1b), a labelled form of the precursor to the diterpenoids(1a), and its incubation with a cell-free enzyme preparation from Taxus x media densiformis, a species of yew tree, were investigated.</p> <p> The investigation into the biosynthesis of taxol(2) was to be accomplished by monitoring the enzymatic transformations of (1b). The synthesis of 1b was accomplished via a convergent method using geraniol, a ten carbon compound, as the starting material. Essentially two molecules of geraniol were chemically manipulated and condensed to give geranyl geraniol which was oxidized to the corresponding aldehyde and then reduced using sodium borotritide. The radioactive alcohol was subsequently converted to the pyrophosphate (1b) using standard methodology. Cell-free extracts of Taxus x media densiformis were prepared and incubated with [1-3H]-GGPP (1b), the intermediates were extracted, and then analyzed by scintillation counting and radioactive gas chromatography. Identification of these labelled intermediates was attempted in order to provide information about the biosynthesis of 2. (Diagram included in thesis)</p> / Thesis / Master of Science (MSc)
72

Sensing the late antique shrine of Saints Cyrus and John: a materialist analysis of an immaterial site

Conley , Jordan 26 June 2024 (has links)
The world of the late antique Mediterranean is characterized by its saints’ shrines—structures that housed the tombs, relics, and other objects associated with holy entities. These shrines—these distinct places—differed in size, status, and degree of ecclesiastical and bureaucratic recognition, but together formed a widespread network of pilgrimage destinations, arenas of miraculous healings, and gathering points for bodies both human and divine, alive and dead, afflicted and non-afflicted. In facilitating such mingling, the shrines served as earthly, localized sites of holiness and saintly intervention, and yet were also involved in broader social, theological, and economic affairs. This dissertation focuses on one late antique shrine—that of Saints Cyrus and John, which likely reached its height of usage and popularity in the sixth and seventh centuries CE. Once located at Menouthis (modern Abuqir) near the Canopic mouth of the Nile (just outside of Alexandria), the shrine is now characterized by its near-absolute lack of material remains. For that reason, it has not been subjected to the types of material analyses performed on comparative sites with extant remains. Moreover, the only literary accounts of the shrine are attributed to a single author: Sophronios, the patriarch of Jerusalem (c. 560-638 CE). Sophronios’ writing is vivid, however, and he depicts the shrine as a vibrant, visceral space of material, bodily, and faunal entanglements. Blood gushes, tumors burst, and figs appear. Snakes call to one another, attendants hasten, crowds gather, and camel feces are revealed as a saint-sanctioned cure for leprosy. A center for sensory encounters of every kind, the shrine literally overflows with human, animal, and material occupants. Sophronios’ texts therefore invite a material, synesthetic analysis of the space, context, and participants of the shrine. This dissertation utilizes methods from studies in the materiality of religion (including so-called “new materialisms”) in order to: 1) build a material analysis of the shrine of Saints Cyrus and John based on its literary sources, and 2) model how scholars might better grapple with late antique pilgrimage sites (both extant and non-extant) and the materia of divine healing. Individually, the dissertation chapters offer separate ways of reassessing and reconstructing the shrine of Saints Cyrus and John. Taken together, they constitute a methodological intervention in the broader study of late antique saints’ shrines.
73

Business incubators : Knowledge transfer and networks creation as key success factors

Villarroel Rojas, Mayra Veronica January 2010 (has links)
<p>The purpose of this research is to analyze business incubators and the relevant factors that take place inside these organizations.</p><p>The methodology used was a case study approach, which investigates a real environment, in this case: NeoEmpresa, a business incubator located in La Paz, Bolivia. The explanatory approach is also considered in this research since the purpose is to explain the business incubation characteristics as well as understand the importance of knowledge transfer and network creation inside business incubators.</p><p>The findings propose that the most adequate incubation model strongly depends on the incubator’s main purpose and that the learning practices that take place inside an incubator involve knowledge transfer, more considered experience transfer, and networking as relevant factors.</p>
74

Business incubators : Knowledge transfer and networks creation as key success factors

Villarroel Rojas, Mayra Veronica January 2010 (has links)
The purpose of this research is to analyze business incubators and the relevant factors that take place inside these organizations. The methodology used was a case study approach, which investigates a real environment, in this case: NeoEmpresa, a business incubator located in La Paz, Bolivia. The explanatory approach is also considered in this research since the purpose is to explain the business incubation characteristics as well as understand the importance of knowledge transfer and network creation inside business incubators. The findings propose that the most adequate incubation model strongly depends on the incubator’s main purpose and that the learning practices that take place inside an incubator involve knowledge transfer, more considered experience transfer, and networking as relevant factors.
75

Etude de la dynamique de formation de nanostructures périodiques sur une couche mince de cuivre induites par impulsions laser nanoseconde et picoseconde à 266 nm / Investigation of dynamic of periodic nanostructure formation on copper thin film by nano - and picosecond laser pulses at 266 nm

Huynh, Thi Trang Dai 20 November 2014 (has links)
Les nanostructures périodiques induites par faisceau laser ont stimulé de nombreuses recherches en raison de leurs applications dans les domaines des technologies micros et nanométriques, telles que la lithographie, la mise en mémoire des données à haute densité, les systèmes nano et micro-électromécaniques (NEMS/MEMS). La dynamique de leur formation sur la surface des couches minces de cuivre (CMC) déposées sur les substrats de silicium et de verre est étudiée dans ce travail. Cette analyse est réalisée en utilisant deux approches de caractérisation : ex situ pour les analyses Microscopie Electronique à Balayage (MEB) et en transmission (MET), Microscopie à Force Atomique (AFM) et in situ pour les signaux de Réflectométrie en Temps Réel (RRT). Les processus de changement d’état (fusion, ablation, décollement…) et des modifications de la morphologie de surface à l’échelle nanométrique sont étudies en variant un nombre de paramètres clés, à savoir : le dose énergétique (la fluence et le nombre de tirs laser), l’épaisseur des CMC et la nature de substrat en régime d’interaction picoseconde et nanoseconde. En effet, les nanostructures avec une période spatiale de 266 nm (proche de la longueur d’onde laser (λ)), 130 nm (λ/2) et 60 nm (λ/4) sont obtenues. Ces différentes nanostructures périodiques ont été rassemblées dans des cartographies 2D et corrélés à la dose énergétique (fluence et nombre de tirs). Enfin, une tentative d’interprétation des mécanismes de formation des nanostructures périodiques sur les CMC générées en régime laser picoseconde, établie sur la base de nos données expérimentales, semble pertinente avec la théorie d’auto-organisation, notamment pour des nombres de tirs laser importants. / Periodic surface nanostructures induced by laser have attracted particular attention because of their applications in the domain of micro and nanotechnologies such as lithography, high density data storage, nano- and micro-electromechanical systems (NEMS/MEMS). The dynamic of their formation on the surface of copper thin film deposited on silicon and glass substrates was investigated in this present work. Two methods are used in this analysis: ex situ analyses by Scanning and Transmission Electron Microscopy (SEM/TEM), Atomic Force Microscopy (AFM) and in situ diagnostic by Time Resolved Reflectivity method (TRR). The process of phase change (melting, ablation, thin film removal …) and surface morphology modification at the nanoscale are studied with respect to irradiation dose (the fluence and the number of laser shots), the thickness of thin film and the substrate thermal conductivity in the pico- and nanosecond regime. Namely, nanostructures with a spatial period of 266 nm (close to the irradiation wavelength (λ)), 130 nm (λ/2) and 60 nm (λ/4) were successfully obtained. The global relationship between the laser parameters (i.e. fluence and number of laser shots) and nanostructure formation was established in the form of a 2D map. Lastly, an interpretation of the mechanism of periodic nanostructures formation on copper thin film induced by picosecond laser was established on the basis of our experimental data, seems relevant to the self-organization theory, particularly, in multi-pulses regime.
76

Thermal and reproductive biology of the lizards sceloporus occidentalis and sceloporus graciosus along an environmental and geographical gradient

Parker, Scott Landsborough 01 January 2001 (has links)
The thermal environment exerts a strong influence on many aspectsof squamate life history. Environmental temperatures constrain daily activity time, fecundity, growth rate, and also influences hatchling phenotype. Cold nest temperatures can slow the development of eggs deposited in the soil, cause developmental abnormalities or result in mortality of embryos.
77

De inkuberade företagen - Är det värt det? : En jämförande studie om inkuberade företags förväntningar samt upplevelser av en Inkubator.

Möcander, Filip January 2020 (has links)
Bakgrund: En inkubator är ett entreprenöriellt utvecklingsprogram för nystartade företag med utgångspunkt att effektiva deras uppstartsprocess. Företag ingår i en inkubation under en tidsbestämd period där de erbjuds affärsutveckling och rådgivning. De agerar i inkubatorns kontorslokaler tillsammans med andra inkuberade företag. Sociala nätverk är en omfattande del av nystartade företags konkurrenskraft och utveckling på marknaden. Genom sociala nätverk genereras rådgivning, kompetens, kapital och affärsmöjligheter. För att nätverken ska fungera krävs det att entreprenörer interagerar och utbyter information vilket skapar en tillit. Förtroende och tillit möjliggjör för att att nätverken ska vara effektiva och givande, vilket dessutom utgör relationen mellan individerna. Inkuberade företag möter olika utmaningar genom att ingå i ett inkubatorsprogram. Nätverk och kompetens kan vara för likartad samt homogen. Dessutom kan förtroendet mellan de inkuberade företagen och inkubatorn i en flexibel kontorsyta vara komplext. Fortsättningsvis att företagens förmåga att utveckla verksamheten vidare minimeras utan inkubatorns stöd.   Problemformulering: Vilka likheter och skillnader innefattar de inkuberade företagen om inkubatorns program?   Syfte: Syftet med studien är att jämföra de inkuberade företagens förväntningar och upplevelser av en inkubator.   Metod: Uppsatsens har ett kvalitativt tillvägagångssätt och en komparativ forskningsdesign. Således en jämförande studie av de inkuberade företagens förväntningar och upplevelser av en inkubator. Kvalitativa semistrukturerade intervjuer har använts för att samla data från respondenter. Fyra olika företag i form av Measure and Change, Världens Chans, Lumispectra samt YLDR intervjuades från samma inkubator (Företagsfabriken).   Slutsats: Samtliga inkuberade företag är överens om att inkubatorns nätverk inte är tillräckligt effektivt. Upplevelsen har inte bemött deras förväntningar på grund av brister i effektivitet, organisering samt intressanta aktörer. Förtroende för inkubatorn har påverkats negativt för samtliga företag förutom YLDR vilket grundar sig i inkubatorns verksamhetsstruktur och tillgänglighet. Samtidigt har det blivit bättre över tid. Kapitalanskaffningen har delvis besvarat de inkuberade företagens förväntningar. Framförallt det sociala och humana kapitalet. Däremot har det finansiella kapitalet inte besvarat något företags förväntningar förutom (YLDR). / Background: A business incubator is an entrepreneurial development program för start up businesses. Firms in a start up phase are a part of the program in a certain amount of time where they recieve an office space, business advice and development. Together with other incubated companies are they developing their business ideas in a flexible office structure. Furthermore are social networks a major competitive advantage for start up businesses where they can receive competence, capital and business oppertunities. Trust is a major component in order to make the social networks to function. Building trust between to firms creates a relation where they can gain different types of advantages and resources. An incubated business can encouter different types of challenges and problem within an incubator such as homogeneus competence and business networks. Also, trust issues against other incubated businesses and finally problems with being able to develope their firm further after the incubation program.    Research Question: What similarities and differences within the incubation program are the incubated businesses comprising?   Purpose: The purpose of the study is to compare the incubated business actors expectations and experiences of an incubator.   Method: The paper has a qualitative research method and a comparative research design. Furthermore a comparative study of the incubated businesses expectations and experiences from an incubators (Foretagsfabriken). The data was gathered from four incubated businesses who are operating within the same incubator. The firms that participated in the study where Measure and Change, Varldens Chans, Lumispectra and YLDR.   Conclusion: The internal and external network has not met the expectations from the incubated businesses. It has not been organized or efficient with enough interesting actors for them to further develope their business. The trust between the incubator and the incubated businesses has been affected negatively except for YLDR. Furthmore, the acess to different types of capital has partially met the expectations that the start up comapnies had, epescially the social and the human capital. However, YLDR was the only company that where their expectations for financial capital was fulfilled.
78

Business Incubators: Wind Turbines of Entrepreneurship? : A qualitative study on University Business Incubators

Andersson, Louise, Müller, Sebastian January 2023 (has links)
Over the past three decades, interest in the topic of Business Incubation and more specifically University Business Incubation, has increased, due to its potential to encourage entrepreneurial activities, which initiate innovation and economic development. The literature on entrepreneurship devotes significant attention to BI as a tool for supporting entrepreneurs in overcoming difficulties associated with starting a business. Meanwhile, the fact that incubators themselves are vulnerable to different challenges needs to be sufficiently highlighted in the research currently in publication. By adopting an incubator’s perspective on developing entrepreneurs and, therefore, its dynamics that form new ventures, this qualitative study has focused on difficulties adjacent to the administration of the incubator. By building on the Black Box model of incubation, the Triad model, as well as Institutionalized entrepreneurship, the researchers have contributed to the phenomena of UBIs, and the many challenges they encounter when incubating business tenants. The thesis has successfully confirmed the inherent value of ensuring the financial viability of publicly financed incubators while shedding light on the challenges involved in achieving self-sufficiency. This examination has delved into the acquisition of government funds by incubators and explored the opportunities and constraints accompanying such support. Building on existing literature, which identifies sustainability and growth as key indicators, this study has provided empirical evidence and analysis that underscores the detrimental impact on the incubator's core mission when these criteria are not maintained.
79

Vulnérabilité des services écosystémiques des sols tunisiens face aux changements climatiques régionaux : sensibilité de la respiration du sol à la température / Vulnerability of Tunisian soil ecosystemic services to regional climatic changes : sensitivity of soil respiration to temperature

Hamdi, Salwa 14 December 2010 (has links)
Afin de mieux comprendre et évaluer l'impact du changement climatique sur les stocks de carbone organique du sol (COS) et les flux de carbone, et en particulier la respiration hétérotrophe du sol (RS), il est nécessaire d'étudier la sensibilité de la RS à la température. Plusieurs études sur les facteurs contrôlant la dépendance de la RS à la température ont été faites antérieurement et montrent que la sensibilité de la RS à la température diminue avec la température. Ces études ont suggéré que cette diminution de sensibilité de la RS à la température était liée à la modification de la disponibilité en substrat. D'autres études ont suggéré que cette diminution est liée à l'adaptation de la communauté microbienne aux températures élevées. La sensibilité de la RS à la température est plus particulièrement critique dans les régions semi-arides, comme le Nord Ouest de la Tunisie où le stock de COS est faible. Il est nécessaire de connaître l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température. Dans cette étude, les échantillons de sol ont été incubés pendant 28 jours après une période de 28 jours de pré-incubation. Les pré-incubations et incubations ont été réalisées à 20, 30, 40 et 50°C. Pour tester l'effet de la disponibilité en substrat sur la sensibilité de la RS à la température, du glucose a été ajouté au sol au début de la période d'incubation. L'analyse des résultats a montré que les températures élevées de pré-incubation réduisent la sensibilité de la RS à la température d'incubation. L'addition de glucose réduit l'effet de températures élevées de pré-incubation sur la réponse de la RS. Il apparaît ainsi que la diminution de la sensibilité de la RS après un mois de pré-incubation aux fortes températures est due à la diminution de la disponibilité en substrat. Elle semble aussi liée à une diminution de la biomasse microbienne. Puisque, le sol utilisé pour cette étude est un Cambi sol Calco-magnésimorphe, une deuxième expérimentation a été réalisée afin de déterminer la part de CO2 provenant des carbonates et la part de CO2 provenant du COS. Cette étude a été réalisée par des mesures des signatures isotopiques (δ13C) du COS, des carbonates et du CO2 émis. Après 28 jours d'incubation, 23±9% de CO2 provient des carbonates. Cette contribution est faible par rapport à la teneur initiale élevée de C-CaCO3 dans le sol (4,3%) et est indépendante de la température d'incubation. Cette étude a montré que la réduction de la sensibilité de la RS aux fortes températures est surtout liée à une réduction de la disponibilité en substrat organique et de la biomasse microbienne aux fortes températures. / To better understand and assess the impact of climate change on the stocks of soil organic carbon (SOC) and carbon fluxes, and particularly heterotrophic soil respiration (SR), it is necessary to study the sensitivity of SR to temperature. Several studies have been achieved to improve the understanding of factors controlling the temperature dependence of SR and showed that the temperature sensitivity of SR decreases with temperature. These studies suggested that this decrease in temperature sensitivity of SR was related to change in substrate availability. Other studies presented microbial adaptation to warmed conditions. The temperature sensitivity of SR is especially critical in semi-arid regions, such as North West Tunisia, where the SOC stock is low. It is necessary to know the influence of substrate availability on the sensitivity of SR to temperature. In this study, soil samples were incubated for 28 days after a 28-day pre-incubation per iod. Pre-incubation and incubation were carried out at 20, 30, 40 and 50°C. To test the substrate availability effect on the temperature sensitivity of SR, glucose was added to soil at the beginning of the incubation period. Results showed that the highest pre-incubation temperature reduced the temperature sensitivity of SR during the subsequent incubation period. Glucose addition reduced the effect of high pre-incubation temperature on SR response. Thus, it appears that the observed decrease in SR sensitivity to temperature after one month pre-incubation at high temperature was due to a reduce in substrate availability and to a decrease in microbial biomass. Since the soil used in this study is a Calcari-Leptic Cambisol, a second experiment was also performed to determine the amount of CO2 from carbonates and the amount of CO2 from SOC. This study was carried out by measurements of the isotopic signatures (δ13C) of SOC, carbonates and emitted CO2. After 28 days of inc ubation, 23±9% of CO2 came from carbonates. This contribution was low compared to the high initial C-CaCO3 content in soil (4.3%), and it was independent to the incubation temperature. This study showed that reduce in the sensitivity of SR to high temperatures was probably due to a reduction in the substrate availability and to a decrease in microbial biomass.
80

Life history and environmental influences on avian incubation and parental care in songbirds

Austin-Bythell, Suzanne H. 13 March 2015 (has links)
Patterns of nest attendance behavior by breeding birds represent a parent-offspring trade-off in which adults balance self-maintenance with parental care decisions. Incubation, in particular, is of interest because adults must provide an environment suitable for embryonic development through nest-building and contact-incubation. We evaluated how adult incubation constancy and nest visitation rates varied with life and natural history traits of temperate and tropical bird species. We found that constancy did not differ by latitude or with nest survival rate. A strong negative correlation between incubation constancy and egg mass relative to adult body mass was present. Birds with low constancy tended to have larger relative egg masses and higher basal metabolic rate. Because adult incubation constancy is relatively plastic (i.e., varies with ambient temperature), birds with larger relative eggs may respond to lower cooling rates rather than direct selection for higher or lower constancy. We then assessed if rates of nest visitation (trips to nests by adults during incubation and nestling phases) followed the predictions of the Skutch hypothesis. Skutch suggested that birds nesting in environments with high levels of nest predation would reduce numbers of trips to their nests so as to minimize the risk of visual detection by nest predators. We found support for the basic pattern predicted by Skutch. We also extended his hypothesis to predict other behavior associated with nesting, such as responses of parents to intruders at the nest. Despite apparently early departure from the nest site, adults with higher visitation rates remained conspicuous around the nest site. Thus, while the flight initiation distance from the human observer was earlier than expected, conspicuousness of behavior was associated with nest visitation rate. Finally, we assessed how an environmental variable, photoperiod, might influence rate of embryonic development in a wild songbird, Sylvia atricapilla. We exposed eggs throughout the incubation period to daily photoperiods consisting of 4 hours of light and 20 hours of dark (4L), 12 hours light and 12 hours dark (12L), 20 hours light and 4 hours dark (20L) and a skeleton photoperiod with two 1-hour pulses of light that framed a 20-hour day. We found that the skeleton treatment group differed significantly from our 4L and 12L, but not the 20L treatment groups. The skeleton photoperiod accelerated embryonic development. We suggest that photoperiod may influence incubation period in wild birds and could account for some portion of the widely observed latitudinal variation in incubation period of songbirds. We encourage others to assess how photoperiod interacts with parental attendance patterns to affect embryonic development. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from March 13, 2013 - March 13, 2015

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