• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 26
  • 26
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 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.
1

Investigation of temporal and spatial characteristics of carbonyl compounds in the Atmosphere in Kaohsiung

Wu, Chun-I 29 June 2007 (has links)
The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nanzi and Siaogang sites in Kaohsiung city. Source apportionment was determined by the factor analysis. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83 £gg/m3) at Nanzi, followed by formaldehyde (5.03 £gg/m3). At Siaogang, the highest concentrations of carbonyls was acetaldehyde (28.91 £gg/m3), followed by formaldehyde (6.92 £gg/m3). The concentrations of total carbonyls was higher at Siaogang (57.86 £gg/m3) than those at Nanzi (49.74 £gg/m3) . The concentrations of total carbonyls at Nanzi were 65.42 £gg/m3 in summer and 25.06 £gg/m3 in winter, and were 85.09 £gg/m3 in summer and 37.12 £gg/m3 in winter at Siaogang, due to the fact that summer has stronger photochemical activities than in winter. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls was higher. The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nanzi and Siaogang sites in Kaohsiung city. Source apportionment was determined by the factor analysis. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83 £gg/m3) at Nanzi, followed by formaldehyde (5.03 £gg/m3). At Siaogang, the highest concentrations of carbonyls was acetaldehyde (28.91 £gg/m3), followed by formaldehyde (6.92 £gg/m3). The concentrations of total carbonyls was higher at Siaogang (57.86 £gg/m3) than those at Nanzi (49.74 £gg/m3) . The concentrations of total carbonyls at Nanzi were 65.42 £gg/m3 in summer and 25.06 £gg/m3 in winter, and were 85.09 £gg/m3 in summer and 37.12 £gg/m3 in winter at Siaogang, due to the fact that summer has stronger photochemical activities than in winter. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls was higher. Source apportionment analysis using factor analysis shows that the principle sources at Nanzi were traffic exhausts (motor, diesel, and gasoline vehicle) and stationary sources (industry, restaurant and chemical processes). The main sources at Siaogang were traffic exhausts (motor and gasoline vehicle), stationary sources (industry and restaurant) and secondary photo-chemical reactions.
2

Temporal and spatial characteristics of atmospheric carbonyl compounds in Kaohsiung Area

Huang, Chin-hung 04 July 2008 (has links)
The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nan-Chie ¡BHsiung-Kong¡BRen-Wu and Lin-Yuan sites. Factor analysis was also used to determine the source apportionment in the Kaoshiung area. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83, 28.91, 11.46 and 10.06 £gg/m3) at four sites, followed by formaldehyde (5.03, 6.92, 7.88 and 6.59 £gg/m3), respectively. The highest concentration of total carbonyls at Nan-Chie and Hsiung-Kong was 65.42 £gg/m3 and 85.09 £gg/m3 in summer, the lowest concentration was 25.06 £gg/m3 and 37.12 £gg/m3 in winter, relatively, the highest concentration of total carbonyls at Ren-Wu and Lin-Yuan was 49.94 £gg/m3 and 55.24 £gg/m3 in winter, the lowest concentration was 24.48 £gg/m3 and 11.78 £gg/m3 in autumn. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls. The results of factor analysis showed that the principle sources at Nan-Chie were traffic exhausts (diesel and gasoline vehicle) and stationary sources (metal assembly, waste treatment, pulp and restaurant). The principle sources at Hsiung-Kong were traffic exhausts (diesel, and gasoline vehicle), stationary sources (leather, chemical process and restaurant). The main sources at Ren-Wu were traffic exhausts (gasoline vehicle) and stationary sources (metal assembly, chemical process and restaurant). The main sources at Lin-Yuan were traffic exhausts (diesel vehicle) and stationary sources (metal assembly, leather, steel production and restaurant).
3

Diurnal variations of the earth's magnetic field throughout East-Asia interpreted in terms of ionospheric winds and electric currents

Kannangara, Sandhya Indrani. January 1980 (has links)
published_or_final_version / Physics / Master / Master of Philosophy
4

Effects of Salinization on Lake Metabolism / Effekter av förhöjd salthalt på sjöars metabolism

Nordström, Emil January 2020 (has links)
With rising salinity levels in many freshwaters across the globe caused by for example sealevel rise and de-icing salts, it becomes important to understand what effect it has on freshwater ecosystems, since the lakes and rivers themselves are important parts in the global carbon cycle. In this study I have looked at what effects increased salinity levels have on different lakes metabolism, specifically oxygen concentration and primary production. The experiment was conducted using mesocosms in three different lakes in Sweden, separated both geographically and by nutrient status (eutrophic, oligotrophic, and dystrophic as well as oligotrophic). The response to increased salinity differed between the lakes; the increased salinity had a strong negative effect on the oligotrophic lake. In general, increased salinity caused a decline in oxygen content, both the maximum value and the amount of diurnal variation, as well as primary production. Therefore, the conclusion is that a rise in salinity will affect lake metabolism in a detrimental way, with a stronger effect on more sensitive lakes. / Med stigande saltnivåer i många sötvatten världen över, orsakade av exempelvis ökande havsnivåer och applicering av vägsalt, blir det viktigt att förstå vilken påverkan detta har på ekosystem i sötvatten då de utgör en viktig del I den globala kolcykeln. I den här studien har jag tittat på vilken effekt förhöjda salthalter har på olika sjöars metabolism, specifikt syrehalt och primärproduktion. Experimentet utfördes med hjälp av mesokosmer i tre olika svenska sjöar, skilda både geografiskt och trofiskt (eutrof, oligotrof samt dystrof och oligotrof). Sjöarnas respons till den ökade salthalten varierade; saltet hade en starkt negativ effekt på den oligotrofa sjön. På en generell nivå så sjönk syrehalten, både maximum värden och dygnsvariationen, samt primärproduktionen vid högre salthalter. Slutsatsen blir därför att ökade saltnivåer kommer att påverka sjöars metabolism negativt, med en starkare effekt på mer känsliga sjöar.
5

Respostas de curto período das características fotossintéticas da alga vermelha Batrachospermum delicatulum a temperatura e irradiância /

Kusakariba, Thiago. January 2007 (has links)
Orientador: Orlando Necchi Júnior / Banca: Ricardo Moreira Chaloub / Banca: Gustavo Habermann / Resumo: Respostas de curto período das características fotossintéticas a temperatura e irradiância foram avaliadas na rodófita Batrachospermum delicatulum em condições naturais e em laboratório. A variação diária dos parâmetros fotossintéticos por fluorescência da clorofila foi amostrada em duas épocas (junho, período frio e seco; outubro, quente e chuvoso) em um riacho da região noroeste do Estado de São Paulo (20o43’24-S, 49o18’21-W). Os valores de RQE e RQP (rendimento quântico efetivo e potencial, respectivamente) apresentaram correlação negativa com a irradiância nas duas épocas e valores similares no início e final do dia, indicando respectivamente alta pressão de excitação sobre o fotossistema II (FSII) e boa capacidade de recuperação e ausência de fotodano ao aparato fotossintético. Os valores de NPQ (extinção não-fotoquímica) também apresentaram correlação negativa com irradiância (significativa apenas em junho), o que possivelmente indica baixa capacidade de dissipação da energia absorvida pelos centros de reação. Sob temperatura e irradiância fixas a variação diária para fotossíntese líquida foi caracterizada por dois picos: o primeiro (maior) durante a manhã e o segundo (menor) durante a tarde. Os valores de ETR (taxa de transporte de elétrons) também apresentaram padrão semelhante, o que demonstra a ocorrência de ritmos endógenos que controlam as taxas fotossintéticas. Curvas de fotossíntese-irradiância e de indução escuro/luz foram testadas em laboratório (sob condições de baixa e alta irradiância) e em campo sob luz natural (não-sombreada) e artificialmente sombreada em duas épocas (junho e novembro). O isolado em cultura e as plantas em condições naturais (novembro) tiveram maiores valores de fotossíntese máxima (Fmax), eficiência fotossintética ( ) e rendimento quântico em baixa irradiância... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Short-term responses of photosynthetic characteristics to temperature and irradiance were analyzed in the rhodophyte Batrachospermum delicatulum under natural and laboratory conditions. The diurnal variation of photosynthetic parameters by chlorophyll fluorescence was sampled in two seasons (June, cool and dry season; October, warm and rainy season) in a stream of northwest region of São Paulo state (20o43’24”S, 49o18’21”W). Values of EQY and PQY (effective and potential quantum yield, respectively) were negatively correlated with irradiance in both seasons and had similar values at the beginning and end of the day, indicating, respectively high excitation pressure on photosystem II (PSII) and good recovery capacity and lack of photodamage to the photosynthetic apparatus. Values of NPQ (non-photochemical quenching) were also negatively correlated with irradiance (significantly only in June) possibly indicating low dissipation capacity of absorbed energy by reaction centres. The diurnal variation of net photosynthesis under fixed conditions of temperature and irradiance was characterized by two peaks the first (higher) in the morning and the second (lower) in the afternoon. ETR (electron transport rate) values also presented a similar pattern, suggesting the occurrence of endogenous rhythm that controls photosynthetic rates. Photosynthesis-irradiance and dark/light (induction) curves were tested in laboratory (under low and high irradiance conditions) and in field under natural light (unshaded) and artificially shaded in two seasons (June and November). Specimens from culture isolate and in natural conditions (November) had higher values of maximum photosynthesis (Pmax) photosynthetic efficiency ( ) and EQY at low irradiance, whereas at high irradiance (laboratory and field), values of were significantly higher than at low irradiance. A positive correlation between of ETR with NPQ... (Complete abstract click electronic access below) / Mestre
6

Processing Techniques of Aeromagnetic Data. Case Studies from the Precambrian of Mozambique

Magaia, Luis January 2009 (has links)
During 2002-2006 geological field work were carried out in Mozambique. The purpose was to check the preliminary geological interpretations and also to resolve the problems that arose during the compilation of preliminary geological maps and collect samples for laboratory studies. In parallel, airborne geophysical data were collected in many parts of the country to support the geological interpretation and compilation of geophysical maps. In the present work the aeromagnetic data collected in 2004 and 2005 in two small areas northwest of Niassa province and another one in eastern part of Tete province is analysed using GeosoftTM. The processing of aeromagnetic data began with the removal of diurnal variations and corrections for IGRF model of the Earth in the data set. The study of the effect of height variations on recorded magnetic field, levelling and interpolation techniques were also studied. La Porte interpolation showed to be a good tool for interpolation of aeromagnetic data using measured horizontal gradient. Depth estimation techniques are also used to obtain semi-quantitative interpretation of geological bodies. It was showed that many features in the study areas are located at shallow depth (less than 500 m) and few geological features are located at depths greater than 1000 m. This interpretation could be used to draw conclusions about the geology or be incorporated into further investigations in these areas.
7

Characteristics and source apportionment of carbonyl compounds in Kaohsiung Area, Southern Taiwan

Huang, Chin-hung 13 June 2012 (has links)
The seasonal and diurnal concentrations of atmospheric carbonyls were measured by the LpDNPH-Cartridge and the microcomputer air sampling device at Nan-Chie and Hsiung-Kong sites in Kaohsiung area. Then, factor analysis and absolute principal component analysis were also used to determine the source apportionment in Kaohsiung area. Total concentrations of carbonyls were higher in Summer than in winter at Nan-Chie and Hsiung-Kong sites. Measurements showed that the highest carbonyls were formaldehyde and acetaldehyde, due to the fact that photochemical activities are stronger in summer than in winter. The concentrations of total carbonyls, formaldehyde, acetaldehyde were showed similar diurnal variations, that highest concentrations were found in the morning and noon, then drop down at afternoon and increased at night. Due to the fact that photochemical activities and vehicle exhausts. C1-C3 ratio indicated the local participation of anthropogenic hydrocarbons was important in the production of carbonyls in the Kaohsiung area. C1/C2 was highest in the summer than in the winter, that photochemical activities cause highest concentrations of formaldehyde, especially in the summer noon. The results of factor analysis and absolute principal component analysis showed that the primary pollution sources at Nan-Chie were traffic exhausts (diesel and gasoline vehicle) and stationary sources (petrochemical and food industry) and restaurant emissions, and the primary pollution sources at Hsiung-Kong were traffic exhausts (diesel and gasoline vehicle), stationary emissions (metal assembly and petrochemical industry) and restaurant emissions.
8

Interference with biological rhythm : a novel approach to metabolic disorders in women

Karlsson, Roger January 1992 (has links)
Women seem to be largely protected against certain ‘welfare disorders’ such as cardiovacular disease and osteoporosis, during their fertile years.The metabolic changes observed during women’s non-menstrual states, i.e. during pregnancy, after the menopause and during use of oral contraceptives, indicate the importance of sex steroids and an undisturbed biological rhythm. Treatment with monophasic, combined oral contraceptives constitutes a model for the non-cyclic state.Growth hormone (GH) is a pituitary hormone that has major metabolic effects. The pattern of GH exposure to the target organ is of vital importance for the effects and changes in rhythm could possibly induce metabolic changes.Growth hormome, cholecystokinin (CCK), osteocalcin and angiotensinogen were used as markers for metabolic effects and the concentrations in serum were recorded in women during non-menstrual states. The clinical material comprised a total of 60 women: 18 healthy non-pregnant, 25 pregnant, one lactating woman and 16 postmenopausal women. Using a portable pump and a non-thrombogenic venous catheter, blood samples could be collected at 30-min intervals during 24-h periods. Furthermore, the effects of estrogen and GH in the regulation of angiotensinogen were investigated in an experimental model in the rat.Oral contraceptives were found to alter the secretion of GH towards a pattern of lower and more frequent peaks, though the total amount secreted during 24 h was unchanged. Oral contraceptives seem to induce a suppression of the 24-h concentrations of CCK, which may be important with respect to weight gain in some women. Osteocalcin in serum display a significant circadian variation. This emphasizes the need for careful timing of single point measurements and the value of continuous blood sampling. Oral contraceptives may reduce osteocalcin serum concentrations. The long-term effects on bone are unknown. During late pregnancy osteocalcin levels are extremely low, which could indicate osteoblast inhibition and reduced bone turnover. The mode of GH administration is important for the plasma concentration of angiotensinogen in the non-pregnant rat. Estrogen effects on this protein may be mediated via a modification of GH secretion. Oral contraceptives not only increase angiotensinogen concentrations in serum but also markedly enhance their variability. Further studies are needed to elucidate the relation between the individual pattern of angiotensinogen and hypertension. / <p>S. 1-42: sammanfattning, s. 43-88: 6 uppsatser</p> / digitalisering@umu
9

Life History Tradeoffs Between Testosterone and Immune Function Among Shuar Forager-Horticulturalists of Amazonian Ecuador

Gildner, Theresa 06 September 2018 (has links)
The sex hormone testosterone supports male reproduction. However, testosterone is hypothesized to suppress immune activity, resulting in a tradeoff between energetic investment in reproductive effort and immune function. The Immunocompetence Handicap Hypothesis (ICHH) therefore argues that testosterone-linked masculine traits honestly signal health status to prospective mates, as only uninfected males should be able to maintain high testosterone levels. Still, this proposed tradeoff remains poorly tested among human men, especially among natural fertility populations experiencing high infectious disease burdens. This dissertation therefore tested the ICHH among indigenous Shuar men of Amazonian Ecuador. Specifically, this project examined testosterone variation patterns and assessed how male investment in reproductive effort is associated with reproductive success and immune function. The first study tested testosterone level variation among Shuar men in relation to body composition, age, and style of life factors. This study demonstrated that age and BMI interactions shape testosterone levels in complex ways, such that the relationship between body composition and testosterone profile varies throughout the life course. The second study investigated whether individual reproductive success was significantly influenced by masculine trait development and parasite load. These results failed to support the hypotheses that masculine traits increased reproductive success or honestly signaled lack of parasitic disease. Instead, a significant positive association was observed between a composite score of masculine traits and Ascaris lumbricoides infection load; suggesting that male investment in reproductive effort may increase parasitic infection risk. The final study assessed whether testosterone levels were negatively associated with four measures of immune function (parasite load, C-Reactive Protein [CRP], Immunoglobulin-G [IgG], and Immunoglobulin-E [IgE]). Testosterone levels were inversely associated with CRP levels and a positive relationship between testosterone levels and Trichuris trichiura infection load was documented, suggesting increased investment in reproductive effort may suppress some aspects of immune function and increase parasite burden. Overall, these studies fail to support the ICHH, but do indicate a context-dependent tradeoff between energetic investment in male reproductive effort and some aspects of immune function; thereby demonstrating complex interactions between physical characteristics, physiological processes, and immune activity in human men. This dissertation includes unpublished, co-authored material.
10

Respostas de curto período das características fotossintéticas da alga vermelha Batrachospermum delicatulum a temperatura e irradiância

Kusakariba, Thiago [UNESP] 18 June 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-18Bitstream added on 2014-06-13T18:09:11Z : No. of bitstreams: 1 kusakariba_t_me_rcla.pdf: 605912 bytes, checksum: 3bb69f50b5447fd8858f1b6b6d084438 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Respostas de curto período das características fotossintéticas a temperatura e irradiância foram avaliadas na rodófita Batrachospermum delicatulum em condições naturais e em laboratório. A variação diária dos parâmetros fotossintéticos por fluorescência da clorofila foi amostrada em duas épocas (junho, período frio e seco; outubro, quente e chuvoso) em um riacho da região noroeste do Estado de São Paulo (20o43 24-S, 49o18 21-W). Os valores de RQE e RQP (rendimento quântico efetivo e potencial, respectivamente) apresentaram correlação negativa com a irradiância nas duas épocas e valores similares no início e final do dia, indicando respectivamente alta pressão de excitação sobre o fotossistema II (FSII) e boa capacidade de recuperação e ausência de fotodano ao aparato fotossintético. Os valores de NPQ (extinção não-fotoquímica) também apresentaram correlação negativa com irradiância (significativa apenas em junho), o que possivelmente indica baixa capacidade de dissipação da energia absorvida pelos centros de reação. Sob temperatura e irradiância fixas a variação diária para fotossíntese líquida foi caracterizada por dois picos: o primeiro (maior) durante a manhã e o segundo (menor) durante a tarde. Os valores de ETR (taxa de transporte de elétrons) também apresentaram padrão semelhante, o que demonstra a ocorrência de ritmos endógenos que controlam as taxas fotossintéticas. Curvas de fotossíntese-irradiância e de indução escuro/luz foram testadas em laboratório (sob condições de baixa e alta irradiância) e em campo sob luz natural (não-sombreada) e artificialmente sombreada em duas épocas (junho e novembro). O isolado em cultura e as plantas em condições naturais (novembro) tiveram maiores valores de fotossíntese máxima (Fmax), eficiência fotossintética ( ) e rendimento quântico em baixa irradiância... / Short-term responses of photosynthetic characteristics to temperature and irradiance were analyzed in the rhodophyte Batrachospermum delicatulum under natural and laboratory conditions. The diurnal variation of photosynthetic parameters by chlorophyll fluorescence was sampled in two seasons (June, cool and dry season; October, warm and rainy season) in a stream of northwest region of São Paulo state (20o43 24 S, 49o18 21 W). Values of EQY and PQY (effective and potential quantum yield, respectively) were negatively correlated with irradiance in both seasons and had similar values at the beginning and end of the day, indicating, respectively high excitation pressure on photosystem II (PSII) and good recovery capacity and lack of photodamage to the photosynthetic apparatus. Values of NPQ (non-photochemical quenching) were also negatively correlated with irradiance (significantly only in June) possibly indicating low dissipation capacity of absorbed energy by reaction centres. The diurnal variation of net photosynthesis under fixed conditions of temperature and irradiance was characterized by two peaks the first (higher) in the morning and the second (lower) in the afternoon. ETR (electron transport rate) values also presented a similar pattern, suggesting the occurrence of endogenous rhythm that controls photosynthetic rates. Photosynthesis-irradiance and dark/light (induction) curves were tested in laboratory (under low and high irradiance conditions) and in field under natural light (unshaded) and artificially shaded in two seasons (June and November). Specimens from culture isolate and in natural conditions (November) had higher values of maximum photosynthesis (Pmax) photosynthetic efficiency ( ) and EQY at low irradiance, whereas at high irradiance (laboratory and field), values of were significantly higher than at low irradiance. A positive correlation between of ETR with NPQ... (Complete abstract click electronic access below)

Page generated in 0.1216 seconds