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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.
321

Drought-Associated Tree Mortality: Global Patterns and Insights from Tree Ring Studies in the Southwestern U.S.A.

Macalady, Alison Kelly January 2015 (has links)
Forests play an important role in the earth system, regulating climate, maintaining biodiversity, and provisioning human communities with water, food and fuel. Interactions between climate and forest dynamics are not well constrained, and high uncertainty characterizes projections of global warming impacts on forests and associated ecosystem services. Recently observed tree mortality and forest die-off forewarn an acceleration of forest change with rising temperature and increased drought. However, the processes leading to tree death during drought are poorly understood, limiting our ability to anticipate future forest dynamics. The objective of this dissertation was to improve understanding of drought-associated tree mortality through literature synthesis and tree-ring studies on trees that survived and died during droughts in the southwestern USA. Specifically, this dissertation 1) documented global tree mortality patterns and identified emerging trends and research gaps; 2) quantified relationships between growth, climate, competition and mortality of piñon pine during droughts in New Mexico; 3) investigated tree defense anatomy as a potentially key element in piñon avoidance of death; and, 4) characterized the climate sensitivity of piñon resin ducts in order to gain insight into potential trends in tree defenses with climate variability and change. There has been an increase in studies reporting tree mortality linked to drought, heat, and the associated activity of insects and pathogens. Cases span the forested continents and occurred in water, light and temperature-limited forests. We hypothesized that increased tree mortality may be an emerging global phenomenon related to rising temperatures and drought (Appendix A). Recent radial growth was 53% higher on average in piñon that survived versus died during two episodes of drought-associated mortality, and statistical models of mortality risk based on average growth, growth variability, and abrupt growth changes correctly classified the status of ~70% of trees. Climate responses and competitive interactions partly explained growth differences between dying and surviving trees, with muted response to wet/cool conditions and enhanced sensitivity to competition from congeners linked to growth patterns associated with death. Discrimination and validation of models of mortality risk varied widely across sites and drought events, indicating shifting growth-mortality relationships and differences in mortality processes across space and time (Appendix B). Pre-formed defense anatomy is strongly associated with piñon survivorship over a range of sites and stand conditions. Models of mortality risk that account for both growth and resin duct attributes had≈10¹⁹ more support than models that contained only growth. The greatest improvement in classification was among trees from the 2000s drought, suggesting an enhanced role for tree defense allocation and/or bark beetle activity during recent warm versus historic cool drought. Accounting for defense characteristics and growth-defense allocation is likely to be important for improving representation of drought-associated mortality (Appendix C). Piñon resin duct chronologies contain climate responses that are coherent and distinct from those of radial growth. Growth responds positively and strongly to previous fall and current winter precipitation, and negatively to late spring and early summer temperature. A relatively equal positive resin duct response to winter precipitation and positive response to mid-to-late summer drought suggests that changes in climate will affect tree defense anatomy in complex ways, with the outcome determined by seasonal changes in precipitation and temperature (Appendix D).
322

Θνησιμότητα και αιτίες θανάτου στην Ελλάδα : 1981-2000

Καλαμπαλίκης, Γεράσιμος 26 August 2008 (has links)
Στην εργασία αυτή μελετάται η θνησιμότητα κατά αιτία θανάτου στον Ελληνικό πληθυσμό για τα έτη 1981-2000. Ειδικότερα μελετάται η θνησιμότητα για οκτώ αιτίες θανάτου και για τα δύο φύλλα και για συγκεκριμένες ομάδες ηλικιών. Η μελέτη γίνεται με τη βοήθεια δημογραφικών δεικτών όπως ο ακαθάριστος δείκτης θνησιμότητας, ο τυποποιημένος δείκτης θνησιμότητας και οι ειδικοί κατά ηλικία δείκτες θνησιμότητας κατά αιτία θανάτου και κατά φύλλο. Εξετάζονται επίσης οι πίνακες συνάφειας με χρήση της θεωρητικής κατανομής x2 (διωνυμική κατανομή) η οποία προϋποθέτει τη σύμπτυξη των δεδομένων με τη μορφή ενός δισδιάστατου πίνακα συχνοτήτων. Στη περίπτωση αυτή οι γραμμές του πίνακα αποτελούνται από τις κατηγορίες της μιας μεταβλητής και οι στήλες από τις κατηγορίες της άλλης, ενώ στον εσωτερικό χώρο βρίσκονται οι συχνότητες που αντιστοιχούν σ' όλους τους δυνατούς συνδυασμούς των κατηγοριών των δύο μεταβλητών. Η πιο απλή περίπτωση ενός πίνακα συνάφειας που εξετάζεται είναι ο τετράπτυχος πίνακας (2 Χ 2) ο οποίος προκύπτει από τη διαξονική ταξινόμηση των συχνοτήτων των δύο δίτιμων μεταβλητών. Τα κύρια αποτελέσματα της μελέτης είναι: - Η μείωση της θνησιμότητας κατά τα έτη που μελετώνται. Το συμπέρασμα αυτό προκύπτει από τη μείωση του τυποποιημένου δείκτη θνησιμότητα, τη μείωση της βρεφικής θνησιμότητας και την αύξηση της προσδοκώμενης ζωής κατά τη γέννηση. - Οι άρρενες υπόκεινται σε μεγαλύτερη θνησιμότητα από ότι οι θήλεις. - Οι αιτίες που παρουσιάζουν αύξηση τα τελευταία έτη είναι, τα ατυχήματα από μεταφορικά μέσα, τα νεοπλάσματα στόματος και οργάνων του αναπνευστικού και τα καρδιακά για τα δύο φύλα, ενώ τα υπόλοιπα νεοπλάσματα αυξάνουν μόνο για τους άρρενες. Όλες οι υπόλοιπες αιτίες παρουσιάζουν μείωση. / -
323

The Association between Hemoglobin Level and Cancer Incidence, Mortality and Inflammatory Biomarkers in Post-Menopausal Women

Grant, Andriene Simone January 2013 (has links)
Background: Knowledge regarding the associations of (i) hemoglobin level (Hb) prior to cancer diagnosis and cancer mortality (ii) the full range of Hb and cancer incidence and (iii) baseline inflammatory/other biomarkers and Hb in older populations is limited. The present study examined the associations of anemia status/Hb with cancer incidence and mortality, as well as the association with inflammatory biomarker levels in post-menopausal women. Methods: Anemia was defined as Hb <1 2 g/dl, while high Hb was defined as Hb >= 15 g/dl, or >= 16 g/dl. Associations were determined in three Women's Health Initiative Study sub-populations. The association between anemia/Hb with cancer mortality was determined in women without (N=21,021) or with (N=2,976) cancer history who had cancers on follow-up. The cross-sectional association of biomarkers and anemia/Hb was determined on 1,001 women with these available data. Finally, the association between anemia/Hb with cancer incidence was determined in women enrolled in the Observational Study/Clinical Trial who did not have a history of cancer/extreme energy intakes/missing follow-up time (N=140,269). Results: Anemia was associated with a 21% higher hazard of total cancer death in participants with, and a 55% greater hazard in participants without cancer history. Anemic women with a history of cancer had twice the hazard of colorectal cancer death. C-reactive protein, TNF-alpha, TNF-beta and TNFR2 were significantly associated with anemia. IL-1 alpha and IL-10 were significantly associated with continuous Hb. Anemia was not associated with cancer incidence in the total population, but anemic African-American women had a reduced risk of any cancer incidence which was not observed in white women (p-interaction=0.03). Women with high Hb had an increased hazard of any (HR: 1.37; 95% CI: 1.17, 1.60) or breast cancer (HR: 1.42; 95% CI: 1.10, 1.84) incidence. Conclusions: Anemia determined prior to cancer diagnosis was associated with total and colorectal cancer death. High Hb was associated with increased risk of total cancer and breast cancer incidence. Anemia was associated with elevated levels of C-reactive protein, TNF-alpha, TNF-beta and TNFR2, while continuous Hb was associated with IL-1 alpha and IL-10. Further research is required to confirm associations and clarify causal mechanisms.
324

I Won't Live On, So I Create: Mortality Salience and Afterlife Belief Strength's Impact on Intention to Engage in Creation-Oriented Consumption

Xu, Huimin January 2006 (has links)
Creative behaviors are part of an average consumer's everyday life. For example, amateur people buy various art and craft supplies from stores like Michael's, purchase studio time to make pottery, and collect camera accessories to help demonstrate their originality in photography. Usually the final creative product can be preserved for a long period of time. These creative activities are avidly pursued primarily because they provide consumers with enjoyment and a sense of fulfillment. I am coining the term "creation-oriented consumption" to refer to this phenomenon, which is one specific type of creative consumption.Terror management theory is used to examine why people engage in creation-oriented consumption. I hypothesize that mortality salience boosts the intention to engage in creation-oriented consumption; and under mortality salience, weakened afterlife belief increases the intention for this type of consumption.Three experimental studies are conducted, each adopting a somewhat different perspective. Study 1 gauges intention to engage in creation-oriented consumption against inaction. It finds that mortality salience increases interest in creation-oriented consumption; and that under mortality salience, weakened afterlife belief increases interest in creation-oriented consumption. Study 2 examines durable creation-oriented consumption's appeal relative to other activities, namely, non-creative activities and creative consumption that does not leave durable traces. The proposed effect of mortality salience is observed only when individuals possess a low level of chronic afterlife belief. Unexpectedly, interest in creative consumption is reduced under mortality salience. Consistent with study 1, study 2 finds that under mortality salience, weakened afterlife belief raises interest in creation-oriented consumption. Study 3 replicates the finding of study 2 that mortality salience dampens general interest in creativity. Taken together, these studies suggest that although creation-oriented consumption ameliorates existential anxiety, it is not the most effective one in the short term.Apart from the major hypotheses, this dissertation also investigates some boundary conditions. Two of the three studies find that the question of whether creative consumption leaves a durable trace is of significance.
325

Is a Daughter Really Like Water Spilled on the Ground ? : Adult Children’s Gender, Filial Support, and Parental Mortality in Rural China

Mangyo, Eiji 02 1900 (has links)
No description available.
326

Maternal Mortality in Cambodia: Efforts to Meet the Millennium Development Goal for Maternal Health

Connell, Sarah Elizabeth 08 November 2011 (has links)
Recent estimates of global maternal mortality indicate that for the first time since the Safe Motherhood Initiative of 1987, deaths due to pregnancy-related causes are on the decline. Defined as the death of a woman while pregnant or within 42 days of termination of pregnancy, maternal mortality is one of the strongest health statistics showing the disparity between poor and rich countries. Although a global decline is documented, challenges to reducing maternal mortality, and meeting Millennium Development Goals (MDGs) for maternal health remain, particularly in many Sub-Saharan African and Southeast Asian countries. This study presents an assessment of Cambodia’s progress towards reaching the Millennium Development Goal of reducing maternal deaths by ¾ by 2015. The report examines issues related to the improvement of maternal health, outlining the magnitude, determinants, and prevention methods of maternal mortality globally and in Cambodia. Cambodia’s health policies and contextual factors impacting the maternal mortality ratio such as dramatic increases of skilled health personnel for delivery, delivery in health facility, and use of antenatal care are identified as key contributors to MMR reduction. Continued progress in reducing maternal mortality in Cambodia requires improvements to midwifery skill, competencies around normal and emergency birthing care, and salaries of midwives as well as an incentive for new graduates to work in the public sector. An increase in the cooperation between government health centers and hospitals are crucial to ensure obstetric referrals, supervision of health center staff, and an improvement in maternal death data collection. Finally a national priority to increase the use of family planning and safe abortion will significantly contribute to the continued reduction of MMR.
327

Social Vulnerability and Health in Older Adults

Andrew, Melissa Kathryn 07 September 2010 (has links)
Vulnerability to adverse health outcomes can be intrinsic (e.g. illnesses, disability, frailty, genetics) or extrinsic (e.g. physical and social environments). The contribution of social factors to extrinsic vulnerability in older adults is the subject of this thesis. Social vulnerability is the degree to which a person’s overall social situation leaves them susceptible to further insults, either health-related or social. This thesis begins with an exploration of how various social factors are associated with health and can be considered to contribute to a holistic concept of social vulnerability. Using a social ecology perspective, seven domains of social vulnerability (engagement, contextual socio-economic status, social support, living situation, self-esteem, mastery, and relations with others) are defined. A social vulnerability index is then developed, in which social factors from all of these domains are combined into a single index, allowing the complexity of social circumstances experienced by older people to be embraced. Social vulnerability, defined using this index, is then studied in relation to health, and is found to be associated with frailty, mortality and cognitive decline. The important impact of social vulnerability on the survival of the fittest older adults (those who are not at all frail) is studied as a special case. How social vulnerability changes over time is then examined using a transitions model based on a parametric Markov chain, with the finding that older people tend to accumulate social deficits over time, but that, importantly, this relentless accumulation of social problems is not a universal experience. The thesis then turns to consideration of frontal lobe cognitive function as a possible mechanism for the association between social vulnerability and health, given the importance of the frontal lobes to social interaction in humans. It finds that the most socially vulnerable people have impaired performance on tests of frontal lobe cognition, but that performance on non-frontal tasks is not similarly associated. The findings presented in this thesis support the importance of social factors for health of older people, and suggest that the social vulnerability index shows potential as a measure which embraces the complexity of older adults’ social circumstances while reducing dimensionality.
328

Gyventojų mirtingumo ir sveikatos apsaugos sistemos tarpusavio sąryšio tyrimas / Investigation of relations between people mortality and health protection system

Urbonavičiūtė, Justina 30 July 2013 (has links)
Gyventojų mirtingumas Lietuvoje kasmet vis didėja, todėl bandysime surasti, kas tam daro didžiausią įtaką. Tiriami sveikatos apsaugos sistemos faktoriai: išlaidos sveikatos priežiūrai (mln. Lt), gydytojų (sveikatos priežiūros specialistų) skaičius ir lovų skaičius ligoninėse. Šiame darbe ieškome priklausomybės tarp gyventojų mirtingumo ir paminėtų sveikatos apsaugos sistemos faktorių. Tyrimas paremtas 1996–2011 metų duomenimis iš Lietuvos statistikos departamento svetainės (www.stat.gov.lt). Darbe tikrinamos įvairios hipotezės, tyrimui atlikti naudojama koreliacinė analizė ir tiesinė regresija. Taip pat bandoma prognozuoti, koks bus mirusių gyventojų skaičius ateityje. / People mortality in Lithuania is increasing every year, so we are going to try to identify, what things make the biggest influence. Investigated factors of health protection system are: expenses on health care, quantity of doctors (health care professionals) and number of hospital beds in Lithuania. In Bachelor thesis, we are searching for a dependence between people mortality and those 3 factors of health protection system mentioned before. This investigation is based on data from 1996–2011 (www.stat.gov.lt). In this work we are testing several hypothesis and for investigation we use correlation analysis and linear regression. Also trying to predict people mortality in the near future.
329

Prostate cancer-specific suvival differences between radical prostatectomy and curative radiotherapy

DEGROOT, JULIE 26 September 2009 (has links)
Background: The relative treatment effectiveness of surgery versus radiotherapy for early-stage prostate cancer is uncertain and randomized clinical trials are unlikely to be performed. This study describes the difference in cause-specific survival between patients treated with radiotherapy versus surgery, using a number of design and analytic steps to mitigate confounding by indication within an observational study. Methods: We conducted a population-based case-cohort study, sampling patients from the Ontario Cancer Registry who were treated or were candidates for cure by radiotherapy or surgery. Cases were those who died of prostate cancer within 10 years. Cause-specific survival was analyzed using Cox-proportional hazard regression, with variance adjustment for the case-cohort sampling. Analysis using intent to treat was compared to that using treatment received. Propensity scores were also calculated and Cox-proportional hazard regression was conducted within each propensity score quintile. We formed instrumental variable groups based on radiotherapy rates in Cancer Care Ontario Regions (CCORs) using the study population sampling frame and checked the instrumental variable assumption of equal distribution of covariates by comparing those covariates across these groups using data from the subcohort. Results: The adjusted hazard ratios for risk of prostate cancer death for radiotherapy compared to surgery were 1.44 (95% CI 0.86-2.40) and 1.84 (1.06-3.17) using intent to treat and treatment received respectively. Stratified hazard ratios comparing radiotherapy to surgery for death from prostate cancer from the lowest propensity quintile to the highest propensity quintile were 0.30 (0.04-2.28), 1.54 (0.35-6.77), 0.90 (0.29-2.82), 2.71 (1.01-7.31) and 1.08 (0.41-2.81). Differences among these hazard ratios were not statistically significant (p=0.13). The distributions of all prognostic indicators were statistically significantly different between instrumental variable groups. Conclusion: Analysis by intent to treat produced a hazard ratio closer to the null than analysis by treatment received, indicating that uncontrolled confounding toward more serious cases getting radiotherapy was present in the analysis by treatment received. Future studies should focus on obtaining enough numbers for subgroup analysis such as the stratification by risk groups. Caution should be used when using the instrumental variable approach in this population, as prognostic indicators were not as equally distributed as expected. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2009-09-24 17:54:09.955
330

Effects of hypoxia and surface access on growth, mortality and behavior of juvenile guppies, Poecilia reticulata (Pisces : Poeciliidae)

Weber, Jean-Michel. January 1982 (has links)
No description available.

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