Exploring the Effect of Climate Change on Biological Systems

The present and potential future effect of global warming on the ecosystem has brought climate change to the forefront of scientific inquiry and discussion. For our investigation, we selected two organisms, one from cyanobacteria and one from a cereal plant to determine how climate change may impact these biological systems. The study involved understanding the physiological and adaptive responses at both the genetic and protein function levels to counteract environmental stresses. An increase in atmospheric carbon dioxide is a key factor in global climate change and can lead to alterations in ocean chemistry. Cyanobacteria are important, ancient and ubiquitous organisms that can aid in the study of the biological response to increasing carbon dioxide. Climate predictions estimate that by the year 2100 atmospheric carbon dioxide will exceed 700 ppm. In our first study, we looked at the transcriptional effect of high pCO2 on the cyanobacteria, Trichodesmium erythraeum. Total RNA sequencing was used to quantify changes in gene expression in T. erythraeum grown under present day and projected pCO2 concentrations for the year 2100. Two bioinformatics methods were used to analyze the transcriptional data. The results from this study indicate that a substantial number of genes are affected by high pCO2. However, increased pCO2 does not completely alter any one specific metabolic pathway. As the climate shifts throughout the world, it becomes essential for crops to withstand weather changes. In our second study, we investigated the function of the temperature induced lipocalin (Tatil) from Triticum aestivum, which is proposed to help plants survive adverse conditions. This protein is part of a functionally diverse and divergent superfamily of proteins called the lipocalins; they share a common three-dimensional structure, which consists of an antiparallel β-barrel and a C-terminal α-helix. Lipocalins are found in various organisms with a wide range of functions such as pheromone activity, lipid transport and coloration. Recently, proteins from wheat and Arabidopsis were identified as lipocalins through the elucidation of three structurally conserved regions. The study is particularly timely, as recent studies within the scientific community have shown that at higher temperatures wheat yields will decrease and production will decline by 6% for each 1°C increase. We analyzed the nature of conservation in a large group of sequentially divergent and functionally diverse lipocalins and identified seventeen highly conserved positions as well as built models of the native three-dimensional state of the wheat lipocalin. Based on these computational studies, the wild-type protein and three variants were chosen for a cellular localization study involving site-directed mutagenesis, a gene gun and a confocal microscope. The results provide support for the hypothesis that the L5 loop is involved in the association of the protein with the plasma membrane. We also developed an expression and purification system to produce the wild-type wheat lipocalin protein. Gel filtration chromatography eluted two different sized proteins. Based on the elution volume, one is believed to be the wheat lipocalin trimer while the other one is the monomer. Circular dichroism and fluorescence spectroscopy show that the biological characteristics of the two proteins are different. In the study, Tatil maintains its structure up to approximately 50°C (122°F). In summary, we provide experimental data to better understand mechanistically how microorganisms and plants adapt to environmental change. In cyanobacteria, we show that T. erythraeum adapts to pCO2 increases by up- or down-regulating its genes. In plants, we provide insight into the way in which Tatil interacts with the plant cell membrane as part of its putative function to facilitate robustness in response to temperature increases. The study of Tatil is vital as this protein is believed to help plants tolerate oxidative stress and extreme conditions which broadens our understanding of plant sustainability in different environments

Behavioral and fMRI-based Characterization of Cognitive Processes Supporting Learning and Retrieval of Memory for Words in Young Adults

A novel word is rarely defined explicitly during the first encounter. With repeated exposure, a decontextualized meaning of the word is integrated into semantic memory. With the overarching goal of characterizing the functional neuroanatomy of semantic processing in young adults, we employed a contextual word learning paradigm, creating novel synonyms for common animal/artifact nouns that, along with additional real words, served as stimuli for the lexical-decision based functional MRI (fMRI) experiment. Young adults (n=28) were given two types of word learning training administered in multiple sessions spread out over three days. The first type of training provided perceptual form-only training to pseudoword (PW) stimuli using a PW-detection task. The second type of training assigned the meaning of common artifacts and animals to PWs using multiple sentences to allow contextual meaning acquisition, essentially creating novel synonyms. The underlying goals were twofold: 1) to test, using a behavioral semantic priming paradigm, the hypothesis that novel words acquired in adulthood get integrated into existing semantic networks (discussed in Chapter 2); and 2) to investigate the functional neuroanatomy of semantic processing in young adults, at the single word level, using the newly learned as well as previously known word stimuli as a conduit (discussed in Chapter 3). As outlined in Chapter 2, in addition to the semantic priming test mentioned above, two additional behavioral tests were administered to assess word learning success. The first was a semantic memory test using a two-alternative sentence completion task. Participants demonstrated robust accuracy (~87%) in choosing the appropriate meaning-trained item to complete a novel sentence. Second, an old/new item recognition test was administered using both meaning and form trained stimuli (old) as well as novel foil PWs (new). Participants demonstrated: a) high discriminability between trained and novel PW stimuli. (d-prime=2.72); and b)faster reaction times and higher accuracy for meaning-trained items relative to perceptually-trained items, consistent with prior level-of-processing research. The results from the recognition and semantic memory tests confirmed that subjects could explicitly recognize trained items as well as demonstrate knowledge of the newly acquired synonymous meanings. Finally, using a lexical decision task, a semantic priming test assessed semantic integration using the novel trained items as primes for word targets that had no prior episodic association to the primes. Relative to perceptually trained primes, meaning-trained primes significantly facilitated lexical decision latencies for synonymous word targets. Taken together, the behavioral findings outlined above demonstrate that a contextual approach is effective in facilitating word learning in young adults. Words learned over a few experimental sessions were successfully retained in declarative memory, as demonstrated by behavioral performance in the semantic memory and recognition memory experiments. In addition, relative to perceptually-trained PWs, the newly meaning-trained PWs, when used as primes in a semantic priming test, facilitated lexical decisions for synonymous real words, with which the primes had no prior episodic association. The latter finding confirms our primary behavioral hypothesis that novel words acquired in adulthood are represented similarly, i.e. integrated in the same semantic memory representational network, as common words likely acquired early in the lifetime. Chapter 3 outlines the findings from the fMRI experiment used to investigate the functional neuroanatomy of semantic processing using the newly learned as well as previously known words as stimuli in a lexical decision task. fMRI data were collected using a widely-spaced event-related design, allowing isolation of item-level hemodynamic responses. Two fMRI sessions were administered separated by 2-3 days, the 1st session conducted prior to, and the 2nd session following word-learning training. Using the same items as stimuli in the fMRI sessions conducted before and after behavioral training, facilitated a within-item analysis where each item effectively served as its own control. A set of stringent criteria, outlined below, were established a-priori describing characteristics expected from regions with a role in retrieving/processing meanings at the single word level. We expected a putative semantic processing region to exhibit: a) higher BOLD activity during the 1st fMRI session for real words relative to novel PWs; b) reduced BOLD activity for repeated real words presented in the 2nd fMRI session relative to levels seen in the 1st fMRI session; c) higher BOLD activity for meaning-trained PWs relative to novel PWs; d) higher BOLD activity for meaning-trained PWs relative to perceptually-trained PWs, e) higher BOLD activity for correctly identified meaning-trained PWs (hits) relative to their incorrect counterparts (misses). Given their previously documented associations with semantic processing, we expected to identify regions in left middle temporal gyrus (MTG) and left ventral inferior frontal gyrus (vIFG) to exhibit timecourses consistent with most of the semantic criteria outlined above. Individual ANOVA contrasts, essentially targeting each of the criteria outlined above, were conducted at the voxelwise level. A fixed effects analysis based on 4 correct trial ANOVA contrasts (corresponding to criteria a-d, above) generated 81 regions of interest; and two individual error vs. correct trial ANOVA contrasts generated an additional 16 regions, for a total of 97 study-driven regions. Using region-level ANOVAs and qualitative timecourse examinations, the regions were probed for the presence of the effects outlined in the above criteria. To ensure a comprehensive analysis, additional regions were garnered from prior studies that have used a variety of tasks to target semantic processing. The literature-derived regions were subjected to similar ANOVAs and qualitative timecourse analysis as was conducted on the study-driven regions to examine if the regions exhibited effects outlined in the above criteria. The above analysis resulted in three principal observations. First, we identified regions in the left parahippocamal gyrus (PHG) and left medial superior frontal cortex (mSFC) that, by satisfying essentially all the above criteria, demonstrated a role in semantic memory retrieval for recently acquired and previously known words. Second, despite strong expectations, regions in the left MTG and left vIFG failed to show activity in support of a role in semantic retrieval for the novel words. On the contrary, the profiles seen in the two said regions, namely a ‘word \u3e novel PW’ and a word repetition suppression effect, were consistent with a role in semantic retrieval exclusively for the previously known words. The latter observation suggests that the novel words have yet to undergo adequate consolidation to engage, in addition to PHG and mSFC, canonical semantic regions such as left MTG. Third, despite the potentially crucial distinctions noted in Chapter 3, left lateral/medial parietal regions implicated in episodic memory retrieval exhibited many similar properties as those outlined for PHG and mSFC above during retrieval of newly learned words. Crucially, instead of exhibiting repetition suppression for real words, as observed in PHG/mSFC, the parietal regions showed the opposite effect resembling the episodic ‘old\u3enew’ retrieval success effect. The latter observation argues against a sematic role and in support of an episodic role consistent with previous literature. Taken together, these observations suggest that in addition to the role played by PHG/mSFC supporting semantic memory retrieval for the novel words, the parietal regions are also making significant contributions for memory retrieval of the novel words via complementary episodic processes. Finally, using item-level timecourses derived from the 97 study-driven ROI, clustering algorithms were used to group regions with similar characteristics, with the goal of identifying a cluster corresponding to a putative semantic brain system. A number of clusters were identified containing regions with anatomical and functional correspondence to previously well-characterized systems. For instance, a cluster containing regions in left lateral parietal cortex, precuneus, and superior frontal cortex corresponding to a previously described episodic memory retrieval system (Nelson et al., 2010) was identified. Two additional clusters, corresponding to frontoparietal and cinguloopercular task control systems (Dosenbach et al., 2006, 2007) were also among the identified clusters. However, the clustering analysis did not identify a cluster of regions with semantic properties, such as PHG and mSFC noted above, that could potentially correspond with a semantic brain system. The above outlined findings from the current study, juxtaposed with prior findings from the literature, were interpreted in the following manner. The two regions identified in the current study, i.e. left parahippocampal gyrus and medial superior frontal gyrus, constitute regions that are used for learning new words, and are also recruited during semantic retrieval of previously well-established meanings. In addition, the current results also suggest complementary episodic contributions to the word learning process from regions in left parietal/superior frontal cortex. The latter observation may imply strong episodic contributions to the observed behavioral semantic priming effects. A potential counter argument, i.e. in support of a semantic basis for the priming effects, is the shared recruitment, in a manner consistent with semantics, of PHG/mSFC by both novel and real word stimuli. The left middle temporal gyrus, a region that the task-evoked and neuropsychological literature consistently associates with word-level semantic processing, was not recruited during memory retrieval of novel words, despite robust engagement by previously known word stimuli. Given their association with category-selective semantic deficits, as well as their role in conceptual/perceptual processing in healthy brains, the memory consolidation literature proposes regions in the lateral temporal lobes as potential neocortical loci for consolidated long-term memory. In the current setting, it is likely the case that the novel words have yet to be adequately consolidated to engage left MTG as did the previously known words. Finally, the left vIFG exhibited similar characteristics as the left middle temporal gyrus, in that it was not recruited by the newly meaning trained stimuli, despite showing engagement by previously known words. Given that the region failed to appear in our primary contrasts, even those targeting real word stimuli, and its absence in other prior studies that have used similar lexical decision tasks as the current study, we have a slightly different interpretation for that region. The left vIFG is typically recruited in task settings that require controlled/strategic meaning retrieval, a process that may not be critical for adequate performance of the lexical decision task as employed in the current study. Taken together, these findings suggest that a relatively small amount of word learning training is sufficient to create novel words that, in young adults, behaviorally resemble the semantic characteristics of well-known words. On the other hand, the fMRI findings, particularly the failure of the newly meaning-trained items to engage regions that are canonically responsive to single word meanings (e.g. middle temporal gyrus), may suggest a more protracted timecourse for the functional signature of novel words to resemble that of well-known words. That said, the fMRI findings identified brain regions (left PHG/mSFC) that, consistent with the memory consolidation literature, serve as the functional neuroanatomical “bridge” that connects the novel words to the eventual functional representational destination

Determinants of Contraceptive Use among Women of Reproductive Age Group in Surma Woreda, Southwestern Ethiopia: Cross Sectional Community Based Study

Back ground: Modern contraceptive plays a vital role in the reduction of maternal and child morbidities and mortalities; prevention of pregnancy is an effective form of primary prevention. The link between fertility and the consequences of population growth can be stabilized by giving more emphasis on contraceptive methods at community level. In remote southern communities of Ethiopia, the contraceptive utilization is still low when compared to other districts in the region. Objective: The aim of this study was to assess determinants of contraceptive use among reproductive aged women in Surma woreda. Methods: A cross-sectional community based study triangulated with qualitative study was conducted from April to May 2015. Multi-stage sampling technique was used to select a total of 584 women participants for the quantitative study, whereas purposive sampling was employed for the qualitative study. Key-informant interview guide and pre-tested questionnaire were used for data collection. Data were entered into Epi-Info version 3.5.3 and analyzed using SPSS version 20. Logistic regression analysis was carried out to see the effect of predictors on the dependent variable. Results: The current modern contraceptive prevalence rate is found to be 3.3%. Among the variables partner approval was significantly associated with modern contraceptive use (AOR=6.006; 95%CI= (1.804, 19.994). The Suri have long-standing tradition of fertility regulation i.e. the rhythm method and a culture that support child spacing. Conclusion: There is low prevalence of modern contraceptive use while traditional contraceptive methods are widely practiced. Partner approval as well as the culture and lifestyle of the community are believed to have influenced modern contraceptive use. Hence, continuous health education on modern contraceptives, male involvement and adequate number of community based agents should be trained to reach the community. Keywords: Contraceptive, Prevalence, determinants, Surma, Ethiopia

Inflation, External market Performance and Government Policy: An Empirical Investigation Using VAR-VECM Approach in the Context of Ethiopia

This study aims at determining the effectiveness of demand management policies in stabilizing the macroeconomic environment of Ethiopian economy. Inflation and Balance of Payments are used as the two indicators of stability. The researcher made use of Co-integrated VAR approach and estimates inflation and balance of payments equations. All together the researcher used data for the period 1976-2011. The findings of the study imply the existence of two-way relationship between inflation and balance of payments. Excess balance of payment surplus leads to inflationary pressures in the economy while inflation booming deteriorates the country’s external balance

Determinants, Challenges and Prospects of Dairy Production and Marketing

The study aims at analyzing determinants, challenges and prospects of dairy production and marketing in Mekelle city. The study was conducted in seven purposely selected local administration of Mekelle city: Semen, Hawlti, Hadnet, Kedamay-weyane, Adi-haqi, Ayder and Quhia. Dairy Farmers from each local administration were selected using Proportional Probability to Size (PPS). Data were collected from 200 dairy producing households and cooperative using structured questionnaire, focused group discussion and in depth interview with key informants. Survey data collected from seven local administrations was analyzed by using descriptive and econometric model analysis. The Ordinary least squire econometric estimation technique was employed to identify determinants that affect dairy production. The model result showed that dairy production was strongly and significantly affected by use of improved feed, demand for milk, number of cross breed milking cows, frequency of getting training, access for credit, and education of the household heads. Shortage of feed & its high price, access for credit, seasonality of demand particularly in fasting time and absence of processing industry were the major challenges of dairy production and marketing in the area. Milk was the most important dairy products marketed in the areas. Dairy producers, retailers, farms, cooperatives were found to be the main milk market channel of the study areas. The dairy market in the study area uses informal marketing system, which shows the under development of dairy marketing. Thus, dairy development interventions should be aimed at addressing both dairy production technological gaps and marketing problems. The study shows that there is a high demand for dairy products. Therefore, dairy processing industries establishment, support for dairy producers and cooperatives, and improving access to services should receive due attention in order to improve dairy production and marketing in the study area by all dairy development stake holders

Assessment on the effects of village savings and loan associations (VSLA) on poverty reduction in Hawassa, Ethiopia

Doctor EducationisFormal microfinance institutions have been an important tool in the fight against poverty in developing countries, but their reach for rural people and urban slum poor are limited. Following this, Village Savings and Loan Associations (VSLAs) are established as an alternative, informal mechanism for saving and borrowing that do not require external capital or ongoing financial or administrative support from a founding organization or government bodies. Thus, this study aimed to assess the effects of women participation in VSLA on poverty reduction with a case study in Hawassa city, Ethiopia. Using a mixed qualitative and quantitative research methodology, the study tried to focus on examining the effects of VSLAs contribution to economic and social wellbeing of households, and decision makings, and women participation in community activities. The study used 254 samples (127 VSLA participants, and 127 non-participants) and collected data using questionnaire and focus group discussion. The study used propensity score matching (PSM) to estimate the impact of women participation in VSLA on average monthly household income, and the result indicated the average effect of women participation in VSLA on average monthly household income of participant women is positive and significant at 5% significant level, ranging from 169.63 Birr/month (nearest neighbor matching) to 141.55 Birr/month (Kernel matching), on average. Besides, comparison between participants and non-participants using hypothesis testing shows that women participation in VSLA has a significant positive association with improvements in household diet, health, children’s education, and women’s involvement in household decisions. However, although hypothesized, no significant association is found in relation to women participation in community activities. Findings from the focus group discussions are also consistent with the results from the PSM and hypothesis testing. Following the findings, the study recommends government and nongovernmental organizations to provide regular, timely and need based capacity building trainings for VSLA participants; Link VSLA participants with formal microfinance institutions; conduct regular monitoring and follow ups by either the city or sub-cities Women Children Affairs Department/offices or concerned government body; different concerned stakeholders in the city including government, nongovernmental organizations, microfinance institutions and others need to work in coordinated manner to solve the recurrent challenges of VSLA participants in Hawassa city; and finally government and/or nongovernmental organizations need to take best practices and lessons from existing VSLAs and expand the VSLA initiative to address more impoverished women in the city

The Impact of Monetary Policy on Banks’ Risk-taking: Evidence from the Post Crisis Data

This study investigates if expansionary monetary policy actions have an impact on banks’ risk taking after the financial crisis. Using time series data from December 2008 to April 2016 from the banking sector, the paper finds no evidence of any impact by asset related expansionary monetary policy actions while credit crunch and expected economic conditions are found to have a significant effect on banks’ risk taking decision. These results imply that the risk-taking channel of monetary policy has been ineffective after the fed funds rate reached the zero lower bound

Child labour and economic growth

This paper examines the relationship between national income and child labour. We are particularly interested in evaluating the economic role of children at different stages of development. Our objective is to show that in the aggregate, at a low level of development the direction of the relationship between the incidence of child labour and per capita income is indefinite. Child labour may increase or decrease with income. Forecasts of the child labour force participation rate as well as per capita gross domestic product are made for each country in the sample. We also forecast future levels of the primary net enrollment ratio in an effort to provide empirical support for our policy recommendations. Using panel data methodology, we find evidence of an inverted-U, Kuznets-like relationship between the child labour force participation rate and per capita GDP. Holding all else constant, forecast results suggest that for those countries on upward sloping part of the curve, child labour is a problem that will persist for many years to come. The growth rates of per capita GDP required to reach 10 per cent child labour by the target date, 2029, range from 2 per cent to 15 per cent. Our results highlight the importance of the identification of other aspects of development as determinants of child labour levels, as well as exploring the role of government policy. Further research opportunities are also presented

An Empirical Evaluation of the Link between Women Participation in Village Savings and Loans Association (VSLA) and Poverty Reduction in Ethiopia

Women's participation is a fundamental prerequisite for gender equality and genuine democracy. It facilitates women's direct engagement in decision-making and is a means of ensuring better accountability to women. This paper assesses the impact of women participation in Village Savings and Loans Association (VSLA) on poverty reduction in Hawassa city, Ethiopia. Using a mixed research methodology, and applying propensity score matching, the study found that women participation in VSLA has a significant positive impact in increasing average monthly household income of participant woman. Besides, women participation in VSLA has a significant positive association with improvements in household diet, health, children's education, and women's involvement in household decisions. The study recommends a reinforcement of government and nongovernmental organizations in providing regular and need based capacity building trainings for VSLA participants followed by a concerted effort to link VSLA participants with formal microfinance institutions