There are numerous different white spotting patterns in the horse, including two of particular interest tobiano and sabino. In the mouse, genetic variation in the gene KIT causes many white spotting patterns. Due to the phenotypic similarity among white spotting patterns in horses and mice, KIT was investigated as the cause of the tobiano and sabino spotting patterns in horses. Initially, the KIT cDNA sequences from horses with several spotting patterns were compared. Three single nucleotide polymorphisms (SNPs) were identified, though none were associated with a spotting pattern. Three novel splicing variants were also observed: exon 17 skipping, exon 18 skipping and alternative splicing of exon 3. Families segregating for a sabino spotting pattern (designated Sabino 1) and exon 17 skipping were discovered. Sequencing revealed a SNP (KI16+1037) within intron 16 that was completely associated with skipping of exon 17. Using a PCR-RFLP for KI16+1037, linkage was discovered for sabino spotting (LOD=9.02 for =0) and presence of the Sabino 1 allele detected in seven breeds. While all horses with this SNP exhibited the Sabino 1 phenotype, some horses with a sabino phenotype did not possess the SNP. This is most likely due to genetic heterogeneity of the phenotype. Fluorescent in situ hybridization (FISH) was used to investigate the possibility of chromosome inversion in the region of KIT. A chromosomal inversion was discovered spanning ECA3q13 to 3q21 using BAC clones containing KIT and other genes in the same region. The ECA3q inversion was completely associated with Tobiano in the eight horses tested by FISH. This inversion may disrupt regulatory sequences of the KIT gene and thereby cause tobiano spotting. Spotting patterns are important to horse breeders for aesthetic as well as economic reasons. Spotting patterns in the horse may also be an interesting scientific model. The two genetic variants discovered in this work are good examples of genetic diversity due to mechanisms other than SNPs. Study of these variants may be valuable for examining the effects of the KIT gene on health traits. In particular, the KIT gene directs many functions of the mast cell, a cell that is involved in the etiology of inflammation.

INTRODUCTION: Obesity is a major public health concern for youth in the United States. Eating behaviors, such as meal skipping and eating family dinner, are associated with obesity. School connectedness and family connectedness assess the degree to which an individual feels that he or she belongs in an environment, and strong feelings of school connectedness are associated with decreased BMI. This study qualitatively evaluates the relationships between feelings of home and school connectedness and specific eating behaviors associated with obesity in an adolescent population. METHODS: Participants were recruited from an adolescent clinic at Boston Children's Hospital. Inclusion criteria for recruitment included adolescents who were: Black/ African American or Hispanic and non-White, between 13 and 19 years of age, and living in the Boston neighborhoods of Dorchester, Roxbury, or Mattapan. Participants were interviewed using a semi-structured interview guide, and participant data was analyzed by systematically identifying thematic language in the data by identifying similar phrases, patterns of descriptions, and notable disparities in participant content. RESULTS: 14 (10 females, 4 males; M=15.8 years of age) were enrolled and interviewed. Mean participant BMI was 27.3. 10 participants rarely/never skipped lunch, and 4 participants often/always skipped lunch. 6 participants ate dinner at home with their family always/ often, and 4 rarely/never ate dinner at home with their family. Most reported that their school's community, quality of education, and small environments were the most important aspects of their school. Of the 4 participants who attended school in the suburbs, 3 were connected or very connected to their school and disconnected from their neighborhoods. Every participant expressed feeling safe at school, but many cited lack of safety as their least favorite aspect of their neighborhood. Some reported that they felt safe, even though they knew that their neighborhoods were unsafe. CONCLUSION: Of the five students who felt 'very connected' to their schools, all but one always/often ate the food provided by their schools. These students discussed the ways in which their schools listened to student suggestions about school food. These feelings may suggest a stronger sense of feeling respected by one's school. Strong feelings of school connectedness in the majority of students who attend school in the suburbs warrant further exploration, as those who experience discordant home and school environments seemed more likely to embrace their school environment than their neighborhood environment. Furthermore, understanding how perceived neighborhood safety may contribute to feelings of home and neighborhood connectedness and possibly eating behaviors at or around home merits further examination.

When a highly deformable elastic sphere impacts a water surface at an oblique angle it can skip several times in a manner similar to a skipping stone. However, this sphere seems to skip more readily and with more ease than a traditional skipping stone. This thesis examines the improved skipping characteristics of highly deformable elastic spheres made from cured silicone rubber. The effect of impact velocity, impact angle, sphere diamter and material shear modulus on ricochet trajectory is experimentally examined using high speed photography and image processing techniques. Experimental evaluation shows that deformation is the primary contributor to an increased lift force upon impact. An analytical model is presented in addition to a regime diagram predicting ricochet results from impact conditions.

Soft and deformable silicone rubber spheres ricochet from a water surface when rigid spheres and disks (or skipping stones) cannot. This dissertation investigates why these objects are able to skip so successfully. High speed cameras allow us to see that these unique spheres deform significantly as they impact the water surface, flattening into pancake-like shapes with greater area. Though the water entry behavior of deformable spheres deviates from that of rigid spheres, our research shows that if this deformation is accounted for, their behavior can be predicted from previously established methods. Soft spheres skip more easily because they deform significantly when impacting the water surface. We present a diagram which enables the prediction of a ricochet from sphere impact conditions such as speed and angle. Experiments and mathematical representations of the sphere skipping both show that these deformable spheres skip more readily because deformation momentarily increases sphere area and produces an attack angle with the water which is favorable to skipping. Predictions from our mathematical representation of sphere skipping agree strongly with observations from experiments. Even when a sphere was allowed to skip multiple times in the laboratory, the mathematical predictions show good agreement with measured impact conditions through subsequent skipping events. While studying multiple impact events in an outdoor setting, we discovered a previously unidentified means of skipping, which is unique to deformable spheres. This new skipping occurs when a relatively soft sphere first hits the water at a high speed and low impact angle and the sphere begins to rotate very quickly. This quick rotation causes the sphere to stretch into a shape similar to an American football and maintain this shape while it spins. The sphere is observed to move nearly parallel with the water surface with the tips of this “football” dipping into the water as it rotates and the sides passing just over the surface. This sequence of rapid impact events give the impression that the sphere is walking across the water surface.

In real-time, two way video communications, how to minimize the end-to-end delay for transmitting video data is very important. Since the delay produced by bits accumulated in the encoder buffer must be very small, we need an improved rate control to encode the video with high quality and maintain low buffer fullness. One approach to reduce the buffer fullness is to skip the encoding frames, but the frame-skipping will produce undesirable motion discontinuity in the encoded video sequence. In this thesis, we study the impact of low delay constraint in H.264 rate control and its improvements. The drawback of the H.264 rate control is it cannot handle the frame-skipping mechanism well. To modify this, we control the quantization parameter of each I-frame to avoid the buffer overflow and frame-skipping. Since encoding the I-frame by different quantization parameter will generate different rate and distortion for a group of pictures (GOP), we use Lagrangian optimization to find the tradeoff between rate and distortion for a GOP. By the estimation models of rate and distortion for a GOP, calculate the Lagrangian cost for each possible quantization parameter of I-frame, the quantization parameter with minimum Lagrangian cost will be our choice for I-frame. Simulation results show that our proposed rate control encode the video sequence with less skipped frames and with higher PSNR compared to H.264 rate control under low delay constraint.

beta-Bungarotoxin (beta-Bgt), the presynaptic neurotoxin purified from the venom of Bungarus multicinctus, consists of the A chain and the B chain, cross-linked by an interchain disulfide bond. In this study, two novel beta-Bgt isotoxins were purified from Bungarus multicinctus venom by the combinations of ion-exchange chromatography and reverse phase HPLC. Amino acid sequencing, peptide mapping and mass analyses revealed that they probably contained the same A chain, but their B chain differed. Consequently, the discrepancies in their biological activity and fine structure reflected the role of B chain in intact of beta-Bgt. In Yeast-Two-Hybrid system, a potassium channel binding protein was identified to interact with the B chain of beta-Bgt. Although the recombinant potassium channel binding protein functionally bound with Ca2+, but it could not prove to bind with BM12 and BM13 as revealed by in vitro cross-linking assay. The A chain genes including A1 chain, A2 chain and A8 chain genes were amplified by PCR reaction. Their nucleotide sequences shared up to 97.5% identity. Alignment of the determined A chain genes with A chain cDNAs revealed that the A1 chain gene was organized with four exon and three intron, while A2 chain gene comprised three exons and two introns. When A2 chain is expressed, the region corresponds to the first exon of A1 chain gene is skipped instead of inclusion of intronic sequence adjacent to the second intron. The resulting A2 chain mRNA encoded a 25 residues signal peptide, which different from A1 chain mRNA with a 27 residues signal peptide. Comparative analyses on phospholipase A2 genes and cDNAs suggest that this is the first report on skipping of exon changes the signal peptide sequence of snake venom proteins.

Thesis (M. Ed.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 47-57).

No description available.

Background: Obesity continues to be one of the largest public health concerns in our nation. The role of eating patterns as a means for weight management has been studied extensively. However, the role of breakfast in weight management is still poorly understood. The purpose of this study was to understand the role of breakfast in weight management by observing the relationships of energy intake and macronutrient composition, specifically protein and fiber, with weight status during early morning and late morning eating occasions. Methods: Data from two multiple pass 24h dietary recalls from NHANES 2005-2010 were used. N= 4542 non-pregnant, non-lactating participants aged 20-65 y who did not perform shift work and who had a BMI between 18.5 and 60 kg/m2 were included. Individuals with missing data for any of the variables were excluded. Data were analyzed with SPSS software version 21. Each of the 2 days was divided into four time periods: time period 1 defined as the first intake of the day occurring between 12:00 a.m. and 4:59 a.m., time period 2 defined as the first intake occurring between 5:00 a.m. and 8:59 a.m., time period 3 defined as the first intake occurring between 9:00 a.m. and 11:30 a.m., and time period 4 defined as the first intake occurring after 11:30 a.m. Time period 2 was designated as “early morning intake” and time period 3 was designated as “late morning intake”. The other two time periods were designated as energy intake eaten the rest of the day. Energy (kcal), protein (g), and fiber (g) intakes were then calculated for the whole day and for each time period. For early morning and late morning intake, energy, protein and fiber were also divided into 5 categories. Those reporting no intake (0 kcals) made up the first category and quartiles were calculated for those reporting energy intakes of ≥ 0.1 kcal. Modified quartiles for the late morning period using the quartile cutoffs for the early morning time period were also calculated. Similarly, those reporting no intake (0 grams) made up the first category for protein and fiber and quartiles were calculated for those reporting protein or fiber intakes of ≥ 0.01 g. Estimated energy requirements (EER) were determined using the prediction equations developed by the Institute of Medicine (IOM 2005). To determine energy intake reporting plausibility, reported energy intake as a percent of EER was calculated. Standard classifications were used for weight status based on BMI. Descriptive statistics (median and 95% confidence interval) were computed for all variables. Multinomial logistic regression analysis was performed to determine associations between morning energy intake, protein, and fiber categories and risk for overweight (OW) and obesity (OB) for both early morning and late morning time periods. For the energy intake categories, Model 1 was controlled for race/ethnicity, age, gender, poverty-income ratio (PIR), smoking status, alcohol consumption, physical activity, self-reported chronic disease, daily eating frequency, and the two day morning eating pattern. Model 2 was controlled for all of the covariates in Model 1 plus energy intake before and after morning eating. Model 3 was controlled for all of the covariates in Model 2 plus energy intake reporting plausibility. For the protein and fiber categories, Model 1, 2, and 3 controlled for the same covariates as the energy intake categories and also controlled for reported energy intake during the early or late morning eating occasions. A p-value of <0.05 was considered statistically significant. Results: For the energy intake categories during the early morning, compared to no morning intake, Model 1 showed a lower risk for OB in Q2, but no other relationships were seen in any of the other quartiles. Similar results were seen in Model 2 where a lower risk for OB in Q2 was present. In Model 3, however, (controlled for energy intake reporting plausibility) the relationship between energy intake in Q2 and a lower risk for OB disappeared and a higher risk for OW and OB became apparent in Q4. For the late morning analysis, Models 1 and 2 were similar in that there was no association between morning energy intake category and weight status, but for Model 3 there was a higher risk for OW and OB in Q2-Q4. When we used the modified late morning quartile cutoffs in the analysis to eliminate potential bias due to the different quartile cutoffs for the early and late morning eating occasions, the higher risk for OW and OB was still present in Q2-Q4 and the ORs were attenuated compared to when the original late morning cutoffs were used. In terms of composition, compared to no morning intake, there were no significant associations seen between early or late morning protein consumption and weight status in any of the models. Additionally, for the early morning analysis of fiber, Models 1 and 2 did not show an association between morning fiber intake category and weight status, but for Model 3 there was a lower risk for OB in Q4. For the late morning analysis, Model 1 showed a higher risk for OW in Q2, but no other relationships were seen in any of the other quartiles. Similar results were seen in Model 2 where a higher risk for OB in Q2 was present. In Model 3, however, this relationship disappeared and no other associations were seen in any of the other quartiles. Conclusion: In comparison to having no morning intake (i.e., “skipping”) there was an elevated risk for OW and OB when consuming higher amounts of energy during the early morning and moderate to high amounts of energy during the late morning. The risk for OW and OB was higher in the late morning compared to the early morning eating occasions, in part, but not entirely, because of the higher amounts of energy consumed during the later morning in comparison to the early morning. Therefore, higher energy in both early morning and late morning increase the risk for OW and OB. Furthermore, later timing may increase the risk for OW and OB, independent of energy intake the rest of the day, since individuals who ate later also had higher energy intakes in the later morning compared to the early morning. In addition, compared to no morning intake of fiber, having a very high fiber intake in the early morning, but not the late morning, may decrease the risk for OB independent of energy intake and fiber intake the rest of the day. These associations may not be apparent unless energy intake reporting plausibility is taken into account.

published_or_final_version / Sports Science / Master / Master of Science in Sports Science