This dissertation studies agricultural input intensification, defined as the increased use of modern inputs such as hybrid seeds, mineral fertilizer, herbicide, and pesticide in African agriculture. It also analyses the potential of this intensification to accelerate productivity growth and tests the effectiveness of two policies, input subsidies and land reforms, in promoting it and consequently in increasing crop yield. In the first essay, we argue that to create the conditions for the emergence of a green revolution in Africa, modern agricultural technologies have to be adopted as a package, not in a piecemeal fashion. This argument is consistent with a conceptual framework that we develop to illustrate the importance of harnessing strategic complementarities among agricultural technologies by adopting them simultaneously rather than sequentially. Based on this framework, we propose a methodology to estimate an index to measure agricultural input intensification in its many dimensions. The index provides a simple and intuitive measure to quantify joint adoption of several inputs and compare it across plots, crops, farmers, and regions. Applying this methodology to maize producers in Burkina Faso and Tanzania, we show that our estimated index is a valid measure of joint input adoption and effectively captures the relative importance of each input as well as the number of different inputs adopted. Using the estimated index, we find that simultaneous adoption of modern inputs in Burkina Faso and Tanzania is limited but not rare. Most importantly, we find that the impact of the adoption of individual modern input on yield is increasing with the level of intensification for others. In the subsequent two essays, we assess the effectiveness of government’s direct intervention through input subsidies and indirect intervention through land reforms in promoting agricultural input intensification and increasing productivity. Our empirical analyses focus on Burkina Faso, a country that has recently implemented a fertilizer subsidy program and is undertaking profound land reforms to improve land tenure security and land transferability among households. The second essay tests the hypothesis that subsidizing only one input might promote or discourage the use of other inputs. We find that fertilizer subsidy for maize farmers in Burkina Faso crowds in the use of hybrid seeds and crop protection chemicals, but discourages the use of manure. The last essay assesses whether the development of rural land rental markets can facilitate land transferability among farmers and increase input intensification and productivity. The findings suggest that land rental transfers land from less talented or committed farmers to the more able but have minimal impact on input intensification. However, our results show that land renters are more productive and better farm managers. These results suggest that the short-term gains from policies that foster the development of land rental markets in Burkina Faso, and more generally Africa, will likely be in term of efficiency rather than widespread adoption of modern agricultural technologies.

The climatology of overshooting convection in tropical cyclones (TCs) is examined using Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). The percentage of TC convective systems with overshooting convection is highest over the North Indian Ocean basin, while the northwest Pacific basin contains the highest population of both TC convective systems and convection with overshooting tops. Convective systems in the inner core region are more capable of penetrating 14 km and the associated overshooting convection are featured with much stronger overshooting properties compared with those in the inner rainband and outer rainband regions. In the inner core region of TCs, convection associated with precipitating systems of higher intensity and intensification rates has a larger probability of containing overshooting tops. To identify the relative importance of shallow/moderate versus deep/very deep convection in the rapid intensification (RI) of TCs, four types of precipitation-convection are defined based on the 20 dBZ radar echo height (Z20dBZ). Distributions of four types of precipitation-convection, and their contributions to total volumetric rain and total latent heating are quantified. It is shown that RI is closely associated with increased and widespread shallow precipitation around the storm center, while moderately deep and very deep convection (or overshooting convection) does not increase until in the middle of RI. This is further confirmed by the study of rainfall and convection evolution with respect to the timeline of RI events. Statistically, the onset of RI follows a significant increase in the areal coverage of rainfall, shallow precipitation, and cyan of 37 GHz color composites upshear-left, which in turn could be used as potential parameters to forecast RI. Very deep convection is most frequent 12-24 hours before RI onset and concentrates upshear-left, but it quickly decreases in the following 24 hours. The percent occurrence of very deep convection is less than 1% for RI storms. The tilt of vortex is large prior to, and near the RI onset, but rapidly decreases in the middle of RI, suggesting that the vertical alignment is a result instead of a trigger of RI.

[pt] As transformações recentes ocorridas no mundo do trabalho trouxeram muitos impactos e muitas conseqüências para as relações profissionais. Uma dessas decorrências pode ser entendida como o fenômeno da intensificação do trabalho, em que maiores dispêndios de energia física e mental são exigidas dos trabalhadores. A maior intensidade do trabalho ocorre a partir de práticas utilizadas pelas empresas com o objetivo de obter maior envolvimento e engajamento das pessoas, a fim de que estas possam aumentar a produtividade individual e, assim, trazer melhores resultados para as organizações. Este trabalho teve como objetivo explorar, analisar e compreender a experiência dos trabalhadores que estão inseridos em organizações reconhecidas por valorizarem a alta performance das pessoas e usarem mecanismos que intensificam o trabalho. Além disso, buscou-se, ainda, averiguar a existência de um conjunto de valores individuais comuns presentes nas pessoas que trabalham sob essas condições. Para tal, foi realizada uma pesquisa qualitativa, de inspiração fenomenológica, utilizando-se de entrevistas abertas. O discurso dos sujeitos foi então analisado e categorizado de acordo com as descrições da literatura sobre intensificação do trabalho e de acordo com a teoria de valores individuais de Schwartz (1994). / [en] The recent transformations in the world of work brought many impacts and consequences for many professional relationships. One of these consequences can be understood as the phenomenon of work intensification, in which greater expenditure of physical energy and mental health workers are required. The greater intensity of work occurs from practices used by companies in order to achieve greater involvement and engagement of people in order that they can increase individual productivity and thus bring about better results for organizations. This study aimed to explore, analyze and understand the experience of workers who are embedded in organizations recognized by the high performance to value and use of those mechanisms which enhance the work. In addition, we sought to also examine the existence of a single common set of values present in people who work under these conditions. To this end, we conducted a qualitative study of phenomenological inspiration, using open interviews. The speech of the subjects was then analyzed and categorized according to the descriptions of the literature on intensification of work and according to the theory of individual values of Schwartz (1994).

No description available.

Disertační práce je zaměřena na kovové a polymerní výměníky tepla. Hlavním předmětem zkoumání je optimalizace teplosměnných ploch za účelem zvýšení účinnosti výměníku tepla. Tyto cíle byly dosaženy experimentálně a numericky pomocí modelování v ANSYS. Na základě dosažených výsledků byla rozpracována technologie křížového navíjení polymerních výměníků z dutých vláken. Experimentální zařízení původně určené pro navíjení tlakových nádrží bylo modifikované pro automatizovanou výrobu polymerních výměníků z dutých vláken, ježto může být použita při jejich masové výrobě. Tato práce se také zabývala výměníky tepla pro klimatizační systémy. Byly zkoumány možnosti využití polymerních výměníků z dutých vláken v těchto systémech. Mimo jiné byla provedena studie vlivu cyklického tepelného zatížení standardního kovového žebrovaného tepelného výměníku.

No description available.

No description available.

Utah ranchers commonly face risks to their livelihoods. The objective of this work was to determine if ranchers could make profitable improvements to private land forage given the combined threat of low beef prices, drought, and possible loss of public grazing. We used linear programming (LINDO) to identify the most profitable solutions for private land investment with an 11-year simulation. Operations were divided into small, medium, and large size classes. Various forage improvements and public permits were options. Two phases of a beef price cycle (peak and trough) and 2 precipitation patterns (wet and drought) were combined as joint favorable or unfavorable scenarios. Simulations were run for each size class of operation under each scenario with a 0, 50, or 100% cut in public grazing. The analysis was based upon a partial ranch budget, namely, cattle and forage revenue less forage investment costs. Under the favorable scenario of adequate precipitation and higher beef prices, all operations followed similar patterns of increasing herd size, retaining calves for sale as yearlings, selling alfalfa hay and barley, and treating various forages for enhanced production. All operations exhibited a positive net present value (NPV) over the 11 years. Reduction in access to public permits, however, reduced NPV more for medium-size operations most dependent on public grazing. Under the unfavorable scenario, operation size affected response to combined effects of drought and low beef prices. Small and medium operations decreased brood herds while large operations tended to increase brood herds. Reductions in public grazing lowered NPV more for the small and medium operations compared to the large operations. Work revealed 3 thresholds that could limit profitability of forage investment. These included: (1) dependency on public grazing for> 15% of total annual forage; (2) operation size <2001 >acres; and (3) beef prices of Across all scenarios and operations it was generally profitable to improve 4 forage types that filled gaps at different seasons to the year: wet meadow, alfalfa hay, irrigated pasture, and crested wheatgrass. Irrigated pasture was most important when precipitation was high, illustrating risks of irrigation in this dry environment.

I rapporten framgår det en termodynamisk analys för reverse water gas shift med att sammanmata etanol för att undvika det långsammaste steget i reaktionen för att producera högre alkoholer. Ifrån ett termodynamiskt perspektiv, verkar det möjligt att utgå ifrån reverse water gas shift för att producera högre alkoholer vid 100 bar med en temperatur på 300C . Reaktionen är exotermisk, vilket gynnas av det låga temperaturer och det rekommenderas höga tryck p.g.a. en mol kontraktion. Jämviktshalterna var låga, det föreslås att ta bort vatten ifrån jämvikten.  I den matematiska modellen utgick det ifrån en kedja-reaktion för att producera högre alkoholer med reverse water gas shift i processförhållanden på 10–200 bar. I modellen utfördes en senstivty-analysis för jämvikten på tryck och vattenborttagning. Genom att ta bort vatten ifrån jämvikten låg CO2 utbytet kring 95% vid 200 bar även vid låga tryck som 10 bar. Inom CO2 hydrering till högre alkoholer är det begränsat med data och reaktionsmekanismen bakom reaktionen är inte riktigt förstådd. Experimentella försök krävs för att få en mer ökad förståelse. I modellen beskrevs CO2 hydrering och resterande reaktioner som en funktion av en sigmoid. Inom litteraturstudien kom det fram till att det fanns ingen kommersiell tillgänglig membran förtillfället för att ta bort vatten inom krävande process förhållanden. Tekniken ser dock lovande ut. / In this work, a thermodynamic analysis for CO2 hydrogenation by co-feeding ethanol to higher alcohols was performed with the HSC software package. The results suggested a high pressure and a low temperature for the reaction. However, it yielded low equilibrium compositions for the higher alcohols even at a high pressure of 100 bar at 300C . Increasing the equilibrium compositions for the higher alcohols can be done by removing water.  A mathematical model was used to analyse the rate-limiting step in a process for the production of higher alcohols from CO2.  In this process, reverse water gas shift (RWGS) reaction was used to convert CO2 to CO, subsequently, the obtained CO reacts with ethanol and hydrogen to produce higher alcohols directly. The mathematical model was developed in MATLAB to simulate how the reaction could behave by feeding CO2, H2 and ethanol at different pressures ranging from 10-200 bars. The water removal effect on the equilibrium is measured in terms of CO2   conversion by achieving 95% for removing water.  The results indicated that the process can be used to convert CO2 to higher alcohols and at a lower pressure. The limiting factor for CO2 hydrogenation is the reaction mechanism, it’s an urgent problem for the development of the catalysts. In this model it was assumed to be a logistic function. The conversion of CO2 into higher alcohols is an important problem that is required to be addressed by more experimental verifications to understand the mechanism. The literature review shows that there is no available membrane for removal of water for the process currently, due to the harsh process conditions, mainly because of the membrane stability. However, membrane technology is a promising method for separation of water/organic mixtures that can be studied further in the future.

Global change profoundly alters biological communities and increases species extinction rates. Recent reports show that odonate species (dragonflies and damselflies) are declining globally, however, odonates can also respond strongly to climate and land use change through shifts in range and phenology - i.e., the timing of life history events. Understanding how and when species respond to rapid environmental change is critical to address conservation risks in a timely way. I assembled a dataset of ~2 million odonate records between 1901 and 2021 and investigated a series of research questions about odonate persistence within historically occupied regions, how species respond across continents, and mechanisms leading to these responses. I discovered that non-target effects of pesticides interacted with temperature increases, leading to higher rates of odonate declines across the United States. Species with greater capacities in shifting their range northward may be more robust to impacts of global change (Chapter 2). Converging across Europe and North America, stronger range limit shifts were associated with stronger shifts in emergence phenology towards earlier spring dates, even though land use histories are highly divergent among regions. It is temperature variability and range geography, determinants of habitat conditions to which species are exposed, rather than ecological traits, that facilitated or hindered range shifts (Chapter 3). Temperature variability interacted with pesticide applications to hinder persistence or establishment in new areas that were otherwise climatically suitable, providing further evidence of impacts of extreme weather to insect declines. Tests of methods commonly used to predict species' distributions under future climate change (Species Distribution Models) revealed that species most likely to decline were also less likely to be well modeled, in terms of their temporal transferability (Chapter 4). This work deepens knowledge of spatial and temporal interspecific variation in species distributions as humans continue to reshape the Earth's ecosystems and climatic processes. This thesis can help improve species-specific conservation planning for species that decline in the face of anthropogenic activities.