Biological and Physical Factors Affecting the Natural History and Evolution of Encapsulated Development

The evolution of reproductive strategies involves a complex calculus of costs and benefits to both parents and offspring. Many marine animals produce embryos packaged in tough egg capsules or gelatinous egg masses attached to benthic surfaces. While these egg structures can protect against environmental stresses, the packaging is energetically costly for parents to produce. In this series of studies, I examined a variety of ecological factors affecting the evolution of benthic development as a life history strategy. I used marine gastropods as my model system because they are incredibly diverse and abundant worldwide, and they exhibit a variety of reproductive and developmental strategies.

The first study examines predation on benthic egg masses. I investigated: 1) behavioral mechanisms of predation when embryos are targeted (rather than the whole egg mass); 2) the specific role of gelatinous matrix in predation. I hypothesized that gelatinous matrix does not facilitate predation. One study system was the sea slug Olea hansineensis, an obligate egg mass predator, feeding on the sea slug Haminoea vesicula. Olea fed intensely and efficiently on individual Haminoea embryos inside egg masses but showed no response to live embryos removed from gel, suggesting that gelatinous matrix enables predation. This may be due to mechanical support of the feeding predator by the matrix. However, Haminoea egg masses outnumber Olea by two orders of magnitude in the field, and each egg mass can contain many tens of thousands of embryos, so predation pressure on individuals is likely not strong. The second system involved the snail Nassarius vibex, a non-obligate egg mass predator, feeding on the polychaete worm Clymenella mucosa. Gel neither inhibits nor promotes embryo predation for Nassarius, but because it cannot target individual embryos inside an egg mass, its feeding is slow and inefficient, and feeding rates in the field are quite low. However, snails that compete with Nassarius for scavenged food have not been seen to eat egg masses in the field, leaving Nassarius free to exploit the resource. Overall, egg mass predation in these two systems likely benefits the predators much more than it negatively affects the prey. Thus, selection for environmentally protective aspects of egg mass production may be much stronger than selection for defense against predation.

In the second study, I examined desiccation resistance in intertidal egg masses made by Haminoea vesicula, which preferentially attaches its flat, ribbon-shaped egg masses to submerged substrata. Egg masses occasionally detach and become stranded on exposed sand at low tide. Unlike adults, the encased embryos cannot avoid desiccation by selectively moving about the habitat, and the egg mass shape has high surface-area-to-volume ratio that should make it prone to drying out. Thus, I hypothesized that the embryos would not survive stranding. I tested this by deploying individual egg masses of two age classes on exposed sand bars for the duration of low tide. After rehydration, embryos midway through development showed higher rates of survival than newly-laid embryos, though for both stages survival rates over 25% were frequently observed. Laboratory desiccation trials showed that >75% survival is possible in an egg mass that has lost 65% of its water weight, and some survival (<25%) was observed even after 83% water weight lost. Although many surviving embryos in both experiments showed damage, these data demonstrate that egg mass stranding is not necessarily fatal to embryos. They may be able to survive a far greater range of conditions than they normally encounter, compensating for their lack of ability to move. Also, desiccation tolerance of embryos may reduce pressure on parents to find optimal laying substrata.

The third study takes a big-picture approach to investigating the evolution of different developmental strategies in cone snails, the largest genus of marine invertebrates. Cone snail species hatch out of their capsules as either swimming larvae or non-dispersing forms, and their developmental mode has direct consequences for biogeographic patterns. Variability in life history strategies among taxa may be influenced by biological, environmental, or phylogenetic factors, or a combination of these. While most prior research has examined these factors singularly, my aim was to investigate the effects of a host of intrinsic, extrinsic, and historical factors on two fundamental aspects of life history: egg size and egg number. I used phylogenetic generalized least-squares regression models to examine relationships between these two egg traits and a variety of hypothesized intrinsic and extrinsic variables. Adult shell morphology and spatial variability in productivity and salinity across a species geographic range had the strongest effects on egg diameter and number of eggs per capsule. Phylogeny had no significant influence. Developmental mode in Conus appears to be influenced mostly by species-level adaptations and niche specificity rather than phylogenetic conservatism. Patterns of egg size and egg number appear to reflect energetic tradeoffs with body size and specific morphologies as well as adaptations to variable environments. Overall, this series of studies highlights the importance of organism-scale biotic and abiotic interactions in evolutionary patterns.

Global Factors Affecting Women's Participation in Leadership

This dissertation is a multi-level, cross-cultural study of women in leadership conducted with both macro-society data and individual-level data aggregated to the country level. The research questions are, “What macro and micro forces are hindering or advancing women into business or political leadership?” “How do these forces impact the level of women’s involvement in business and political leadership in a particular country?” Data was collected from 10 secondary sources, available for 213 countries, and includes about 300 variables for business leadership (N=115) and political leadership (N=181). To date, most women in leadership research has been Western- or US- based, and little rigorous empirical, multi-level research has been done across countries. The importance of cross-cultural studies on women in leadership stems from the potential to better understand why some countries have more women in positions of both business and political leadership; and the factors that affect women’s involvement in such positions in different countries. A “Levels of Women’s Participation in Leadership” country model is tested using cluster and discriminant analyses. Results indicate that the factors that affect women’s participation in leadership in countries with fewer women leaders are different from the factors that affect women’s participation in countries with high levels of participation. This dissertation proposes that initiatives to increase participation of women in leadership need to consider the relevant factors that significantly affect countries at certain Levels of Women’s Participation in Leadership.

Factors affecting airport route development activity and performance

Airports have become increasingly active in route development as a means of attracting, growing and retaining air services. However, little is known about the different levels of route development activity at airports, or the extent to which route development activity affects performance. Based on the findings of a survey of 124 airports worldwide, this study finds that larger airports are significantly more active than smaller airports. It also finds that private airports are more active than public airports, and that airports in Europe are more active than airports in other world regions, although differences according to ownership and location are not significant. Route development activity has a significant positive effect on performance. Factors associated with the airport business environment (market turbulence, competitive intensity, market growth and airport constraints) were not found to have a significant moderating effect on the relationship between route development activity and performance. However, two factors were found to have a significant direct effect on performance; market growth has a significant positive effect while airport constraints have a significant negative effect.

Organisational factors affecting transition from children’s to adult services by young adults with life-limiting conditions in Ireland

Factors affecting transition to second year of an engineering degree

Much research has focused on students’ transition from secondary school to university. Less is known about the transition from first to second year of a university degree programme. Given the difficulties that many students face at this stage of their education, research into the relevant factors is required. Through questionnaires and focus groups, views of second- and third-year aerospace and mechanical engineering students in our university have been gathered. A large majority believed that both the volume and difficulty of work increased in second year. Many stated that first year was slightly too trivial and could have been made more challenging to prepare them better for second year. Different teaching and assessment styles in second year were considered to affect attendance and performance. The survey revealed that students were generally very well settled into university life by the end of first year and were happy with their choice of course and only 23% reported that financial responsibilities have had a negative effect on their academic performance. Differences were observed between male and female students. Male students believed that transition was helped by having regular assessments and by worked examples in lectures. Females found the teaching staff were the most helpful factor for a successful transition. The results indicate that males require more structure and guidance whereas females are more independent and settle in better.

Size-selective mortality and environmental factors affecting early marine growth during early marine life stages of sub-yearling Chinook salmon in Puget Sound, Washington

Thesis (Master's)--University of Washington, 2016-08

Examining Factors Affecting Attitudes toward Nuclear Power in Taiwan

Thesis (Master's)--University of Washington, 2016-06

Factors affecting the prognosis of Albanian adult patients with generalized tetanus

Background. Despite systematic vaccination of the population, tetanus continues to be a health problem in Albania, as in some other developing countries. In this study, our intent was to evaluate prognostic factors relating to death in adult patients with generalized tetanus. Methodology and patients. All the patients (60) included in the study were hospitalized at the regional hospitals of Shkodra and Korça, and the University Hospital Centre “Mother Theresa” of Tirana, Albania, during the period of 1984-2004. They had a mean age of 49.1+14.4 years, 43 (71.7%) were males and 40 (66.6%) of them lived in rural areas. The mean incubation period was 12 days and the case-fatality rate (CFR) was 38.3%. Results. The CFR in patients with an onset period ≥2 days was 21.7% and in those with <2 days was 48.6%, OR=0.29 (p<0.05). Patients >50 years old had a CFR=60.87% (OR=7, p<0.05). We found the high CFR to be significantly associated with urban residency, male gender, complicated wound, head localization, fever ≥ 38.4 °C, tachycardia > 120 beats/min, and hypertension. Discussion. The main prognostic factor of those analyzed in our study appeared to be the onset period and the age of the patients. We didn’t find significant differences in CFR in patients with different incubation periods. Clinicians must take into account that wound complication and localization, tachycardia and hypertension, high fever, male gender and urban residency significantly influence the prognoses of adults with generalized tetanus.

Key factors affecting purchase intention in Russian online context

Russian e-commerce has drawn a lot of attention in academic publications as well as in public media lately. The market is growing with a speed of rocket offering companies enormous business opportunities. However, combination of Russian culture, consumer online purchasing and decision-making process forms a subject yet completely unknown. From international online business perspective it is vital for companies to know how a culture affects consumer’s purchase decision and what are the key elements that need to be modified in order to successfully expand online operations to Russian market. Here, the main purpose is to define the key factors affecting Russian consumer’s online purchase intention. In order to answer the main research question, firstly the role of culture in purchase intention context is researched. Secondly, focus is drawn to the factors that affect online purchase intention. Lastly, it is researched how Russian culture is affecting e-commerce attributes modification. The objective is not only to expand the theoretical understanding of the subject but also to provide companies with a clear vision on how the online operations should be conducted in Russian online market. Ranganathan’s and Jha’s conceptual framework was chosen as a ground theory in this study. Here, three main categories Computer Self-Efficacy and Past Online Experience, Website Quality and Costumer Concerns form basis for the study. Various articles and academic literature supplemented this theoretical approach. Qualitative research method was adapted and the study was conducted through five expert interviews. As a conclusion it can be stated that culture forms a ground for entire purchase decision-making process in online context. Results from the interviews were grouped according to main three theoretic categories and placed with Ranganathan’s and Jha’s original framework. This formed a new theoretical framework that defines diverse factors affecting specifically Russian consumer’s online purchase intention. This study suggests that following factors need to be taking into serious consideration in Russian online context: photography style, detailed product and company information, colors, language, product variety, reviews, recommendations, strong social media presence, fast check out and minimalistic order information, counterfeit fear, cash on delivery payment, training and guidance, extensive customer service, consumers’ insecurity, inexperience, high interest for technology and their individualistic personality.

Factors affecting fertility in frozen-thawed boar sperm

Frozen-thawed boar sperm holds the potential to have an impact on the future of the swine industry. Utilization of this technology could improve a swine producer’s ability to access top-tier genetics from around the world, to improve efficiency, profitability, and the quality of product to meet consumer demands. Effective application of frozen-thawed sperm can help reduce the potential risk associated with devastating economic loss due to the spread of disease. Frozen storage of boar sperm also provides a safeguard in the event of disease outbreaks, as genetic material from paternal lines can be preserved and banked for repopulation purposes. Historically these benefits have been masked by reduction in fertility measures such as litter size. The reduced fertility results from the damage sustained by the sperm cell during cryopreservation. However, increased understanding of this damage has lead to improved cryopreservation methods, ultimately increasing post-thaw viability and fertility. Enhancements in breeding technology have also resulted in a better understanding of the AI methods required to achieve acceptable farrowing rates and litter size. Fertility following AI with frozen-thawed sperm is approaching that of liquid stored sperm, and producers may soon reap the benefits of this technology. This thesis will outline the current swine industry, opportunities for utilizing frozen-thawed sperm, the main components of sperm, why they are susceptible to damage, and current freezing and breeding practices. Objective 1 was to develop a cryopreservation protocol for our lab that resulted in consistent post-thaw motility ( ≥ 40%) that would eventually be used by Illinois boar studs for domestic and international sale of frozen sperm. Evaluation with both manual microscopy and CASA methods were conducted to verify quality. A preliminary breeding trial was then conducted to test the fertility of sperm frozen with this method. There were 41 ejaculates from 23 boars used for freezing. Sperm were frozen at 1.4x109 sperm/mL, averaging 55.61.1% (meanSE) motility, following thaw. The samples assessed were not different (P>0.05) in motility when compared with manual or CASA systems, and results were most reliable at a 1:40 sperm dilution. In the preliminary breeding trial, gilts (n=14) were inseminated with either a single (n=10) or double (n=4) AI using 1, 2, or 4x109 motile, frozen-thawed sperm. Overall, the resulting pregnancy rates averaged 71.4% and numbers of normal fetuses per litter averaged 15.51.3 per litter. A feasibility study for freezing cost per ejaculate was estimated at $275/ejaculate or $11/dose of frozen-thawed semen at standard doses of 5x109 total frozen-thawed sperm. This cost estimate did not include genetic value, fixed equipment costs, depreciation, or variable lab space fees. Objective 2 focused on the proper methods for breeding with frozen-thawed boar sperm to achieve fertility. Our hypothesis was that increased numbers of inseminations and increased numbers of motile frozen-thawed sperm would improve pregnancy rate and litter size. Results showed acceptable fertility at high sperm numbers, but also the optimal method for insemination with the lowest dose tested. Gilts (n=111) responded to synchronization methods and were bred with 1, 2, or 4x109 motile frozen-thawed sperm from six boars using a single AI at 32 h, or a double AI, with the first AI at 24 and 32 h following estrus. Ultrasound was conducted at 12 h intervals to estimate the time of ovulation. On day 32 of gestation, overall pregnancy rate (73%) and number of normal fetuses per litter (10.80.5) across all treatments did not differ, and were not affected by number of motile sperm, or the interaction of number of motile sperm and number of inseminations. However, the number of inseminations tended to affect (P=0.14) the number of normal fetuses. Litter size increased with a double AI compared to single AI. Multiple inseminations helped to allow insemination to occur close to ovulation in response to variation in the time of ovulation. Both pregnancy rate and number of normal fetuses were greater when the time of the AI at 32 h occurred closer to the estimated time of ovulation (P<0.05). In addition, other factors such as presence of an abnormal ovary at day 30 decreased (P<0.001) pregnancy rate, while boar affected number of normal fetuses (P<0.01). Analysis of our data using a fertility index revealed doses of 2x109 motile sperm with multiple AI can achieve acceptable fertility with use of less sperm, when compared to AI using 4x109 motile sperm. The methods described here will investigate the potential for improved fertility when using frozen-thawed sperm, while accounting for variation in time of ovulation.

Investigations of the present factors affecting the population characteristics and relative abundance of nile perch (Lates niloticus) at selected trawling sites of western part of Lake Victoria, Uganda, Kagegi Gulf

This report is based on the investigation of the factors affecting population characteristics and relative abundance of Nile perch in selected sites of Kagegi Gulf Lake Victoria Uganda in the month of November 2006. Nine (9) stations were sampled at depth strata of 0-10, 10-20, 20-30 and 30-40 m the mean catch rates were as follows; 8.75±5.5, 4.77±2.3, 6.33±0.3 and 1.34±1.1 tonnes per square kilometer respectively. The catch rates differed at various depth levels with p-value of 0.2940 at 5% level of significance. Limnological parameters were temperature 25.15±0.28, 23.68±0.20, 24.74±0.13 and 25.3±0.20°C; pH of 8.0±0.00, 7.7±0.11; 7.66±0.33 and 6.32±0.14, dissolved oxygen 7.37±0.24, 6.44±0.30, 6.32±0.14 and 6.22±0.14 mg/l; Total nitrogen 589.82±97.2, 514.34±68.8, 690.44±257.8 and 809.03±45.02 µgL-respectively with a p-value of 0.4392 at 5% level of significance. Prey type of Nile perch indicated 65.2% of haplochromine in 0-10 m depth and other strata >10 metre were dominated by Caridina nilotica. Generally investigations indicated that the catch rates of Nile perch at Kagegi gulf in various depth strata probably depended on both the physical and chemical parameters mentioned above.

Environmental factors affecting maerl bed structure in Brittany (France)

This study used a large spatial scale approach in order to better quantify the relationships between maerl bed structure and a selection of potentially forcing physical factors. Data on maerl bed structure and morpho-sedimentary characteristics were obtained from recent oceanographic surveys using underwater video recording and grab sampling. Considering the difficulties in carrying out real-time monitoring of highly variable hydrodynamic and physicochemical factors, these were generated by three-dimensional numerical models with high spatial and temporal resolution. The BIOENV procedure indicated that variation in the percentage cover of thalli can best be explained (correlation = 0.76) by a combination of annual mean salinity, annual mean nitrate concentration and annual mean current velocity, while the variation in the proportion of living thalli can best be explained (correlation = 0.47) by a combination of depth and mud content. Linear relationships showed that the percentage cover of maerl thalli was positively correlated with nitrate concentration (R2 = 0.78, P < 0.01) and negatively correlated with salinity (R2 = 0.81, P < 0.01), suggesting a strong effect of estuarine discharge on maerl bed structure, and also negatively correlated with current velocity (R2 = 0.81, P < 0.01). When maerl beds were deeper than 10 m, the proportion of living thalli was always below 30% but when they were shallower than 10 m, it varied between 4 and 100%, and was negatively correlated with mud content (R2 = 0.53, P < 0.01). On the other hand, when mud content was below 10%, the proportion of living thalli showed a negative correlation with depth (R2 = 0.84, P < 0.01). This large spatial scale explanation of maerl bed heterogeneity provides a realistic physical characterization of these ecologically interesting benthic habitats and usable findings for their conservation and management.

Factors affecting gut metabolism and bioavailabilty of orange juice flavanones in humans

Several studies have supported a beneficial role of dietary flavonoids in reducing the risk/progression of chronic diseases (including hypertension, cardiovascular disease, certain cancers, type-2-diabetes, cognitive dysfunction, age-related bone disease). Their beneficial properties are likely to be affected by their structure, distribution in foods, food matrix, life habits (physical activity). Most dietary polyphenols reach the colon where they are metabolized to phenolic acids by gut bacteria. Lack of knowledge of the factors affecting flavonoid metabolism and bioavailability hinders understanding of their health effects. Therefore, this thesis aimed to investigate the effect of factors on bioavailability and metabolism of dietary polyphenols from orange juices (OJ) in in vitro and in vivo studies. In chapter 3, the variability of orange juice polyphenolic content was assessed using in vitro models of the human gastrointestinal tract. Chapter 4 investigated the reduced urinary phenolic acids after OJ and yoghurt (Y) in humans compared to OJ alone using in vitro models of the human gut. In chapter 5, raftiline and glucose were tested for effects on metabolism of hesperidin (flavanone not OJ). In chapter 6, an intervention study of 4 weeks moderate intensity exercise determined whether exercise affected bioavailability and metabolism of OJ flavanones in healthy sedentary females. The studies in this thesis showed that food sources, food matrix and physical exercise may determine the significant variations in bioavailability and metabolism of flavonoids, seen in a number of studies. These factors could result in differences in bioactivity and bioefficacy of polyphenols, and need to be taken into account in further studies of the effects of flavanones on disease risk.

Factors Affecting the Body Mass Index in Adolescents in Portuguese Schools

The prevalence of overweight and obesity among children is increasing; hence, it was aimed to assess the Body Mass Index (BMI) in school children aged from 10 to 18 years for girls and to 17 for boys, as well as to identify the factors influencing BMI. This study included 742 students who answered a questionnaire previously approved for application in schools. The results showed some sociodemographic factors associated with BMI classes: age, school year, practicing high competition sport, being federate in a sport or having a vegetarian diet. The educational factors associated with BMI classes included only seminars given at school by a nutritionist. Behavioural factors significantly associated with BMI included: learning in classes, playing in the open air, reading books or use of internet. As conclusion, the results demonstrated that several factors affect BMI, and hence some actions could be taken in order to change them so as to reduce the prevalence of overweight, namely reinforcing the role of school and a more active participation of nutritionists in the education of the adolescents.