2923 research outputs found
Sort by
How the Notch Signaling Pathway and Mediator Work Together to Regulate hASC Self-Renewal
Get PDFObesity is a serious medical condition resulting from excess body fat that triggers changes in both quantity and quality of various cells that reside in adipose tissue, including adipose stem cells. Adipose derived stem cells are multipotent, self-renewing cells that have the ability to differentiate. This process can be controlled by environmental stimuli, transcription factors, and signal cascades that lead to gene transcription and protein expression specific to the cell’s fate. The Mediator complex and the Notch signaling pathway are two complexes that allow this to occur. There is still much unknown about the Mediator complex, the Notch signaling pathways, and their interaction, especially during adipogenesis. Here we describe the expression profile and activity of MED12, Notch1, Notch3, Jagged1, and Jagged2 in self-renewing human adipose stem cells and determine the impact each gene has on expression and activity in self-renewing hASC’s. We observed a MED12 knockdown leads to decreased expression and activation of Notch3; MED12 may be required to regulate the transcript and expression of Notch3. Notch3 knockdown leads to decrease MED12 transcript and protein; Notch3 may be required to maintain appropriate levels of MED12 expression. Jagged1 knockdown leads to a decrease in MED12 transcript, but has no discernible effects on protein expression. More research is needed to investigate the relationship between Jagged1 and Notch3
Finding Change Agents: A Qualitative Case Study on Perceptions of Education Leaders During the Implementation of the Next Generation Science Standards
Get PDFThis study is a qualitative case study of middle schools located in a rural public school district in a southern state in the United States that has implemented the Next Generation Science Standards (NGSS) which explored the roles of education leaders in the implementation of NGSS. Participants included teachers, instructional coaches, and district administrators. The findings of the study include how a lack of training for NGSS impacted the effectiveness of education leaders, district leadership focused on curriculum instead of the standards, the response to teacher frustrations led to an adversarial relationship with the district, and education leaders exist in many contexts within the district. Education leaders can benefit from the findings of the presented study by understanding the challenges faced by this district and how education leaders within the district responded to those challenges
Mitigation of End Zone Cracking in Precast Prestress Concrete Girders
Get PDFPrecast prestressed concrete girders have been widely used to construct bridges in the United States. Recent advancements in high-performance concrete and newly developed girder sections allow the span of girders to be extended significantly. Generally, bridges with longer spans require deeper girders and use more prestressing strands; the latter exacerbates the end zone cracking in pretensioned concrete girders when prestressing strands are released. Various types of end zone cracks have been observed, including horizontal and inclined cracks in the web, and bottom flange cracks. This dissertation explores two possible options to mitigate the end zone cracking in precast prestressed concrete girders, including the use of shape memory alloys (SMAs) and ultra-high performance concrete (UHPC) at the girder ends. Experimental work was conducted on the use of SMA wires to apply vertical prestress in the end zone of prestressed girders to counter the bursting stresses as a result of prestress transfer. The end zone behavior of UHPC in prestressed girders was also studied to evaluate its effect on enhanced splitting resistance. The relationship between the splitting resistance from the vertical reinforcement and UHPC at the girder ends and applied prestressing force was examined experimentally and analytically. The experimental study indicated that the use of SMAs successfully introduced vertical prestress at the prestressed concrete beam ends, and therefore can increase the splitting resistance and concrete cracking at prestress can be possibly mitigated or eliminated. The laboratory tests showed that splitting resistance was significantly increased due to the use of UHPC at girder ends. It is suggested to keep the tensile stress limit of 20 ksi in the reinforcing bars to control the crack width, as specified for conventional concrete girders. The collected test data showed that the resulting splitting stresses in the prestressed UHPC girder ends were acceptable
Science Instructional Leadership Knowledge: A Qualitative Case Study
Get PDFThis qualitative case study aimed to investigate instructional leaders’ depths of science content knowledge and pedagogical content knowledge and how their depths of that knowledge supports effective instructional leadership. Implementation efforts around the Next Generation Science Standards (NGSS) have highlighted the need for science instructional leaders to have in-depth content and pedagogical knowledge to function as effective instructional leaders in secondary science classrooms across the United States. Semi-structured interviews with 19 teachers and instructional leaders in a public high school in the southern United States informed the study. The findings revealed that teachers expect instructional leaders to have higher levels of science content knowledge and pedagogical content knowledge to serve in their leadership roles. The findings also suggested science instructional leadership is directly related to instructional leaders’ selfefficacies and self-perceptions. For practical implications, instructional leaders at the secondary level may consider these results for reflection on practice and future planning of professional learning for overall school improvement. Recommendations for future research include expanding the sample population to include multiple school districts, rural school districts, and across content areas
The Moderating Role of Experiential Avoidance between Child-Caregiver Dynamics and STEM motivation
Get PDFThe National Academy of Sciences released a report that discussed the increased need to improve interest and retention of Science, Technology, Engineering, and Math (STEM) careers in the United States. Early childhood factors within one’s family plays an essential role in the process of career decision making, self-concept, and vocational identity. The current study examined the relationship experiential avoidance has on early family dynamics (i.e., family environment, differentiation of self, attachment, and perceived parenting) and perceived motivation in STEM. A total of 231 participants currently enrolled in a Southern University taking a STEM course (Psychology, Biology, Social Science, Computer Science, Engineering, Mathematics, Statistics, and Physical Science) were surveyed using online Likert-Type questionnaires. Participants were surveyed to determine the potential moderating role of experiential avoidance on the relation between early family dynamics and STEM motivation. Results indicated evidence that experiential avoidance moderates the relation between avoidant attachment style and perceived parental care on STEM motivation
Developing Continuous Measures of Trust for Human-Automation Systems
Get PDFDecision aids are developed to ease cognitive load on operators interacting with complex automation systems; however, critical human components are often ignored during design. Finding an appropriate balance of automated assistance and operator trust is paramount in achieving optimal output from the human-automation interaction. Establishing a consistent metric of trust measurement will enhance the functional design of automated decision aids, especially as the use of eye tracking opens the field to the use of real-time measurements. This study will task participants to make measurements, assisted by a decision aid system, within a bone defect model image. The study will test for correlation between eye tracking data and participant trust survey answers. The researchers hypothesize that results from this experiment will indicate an inverse relationship between self-reported trust and gaze data, as the research participants will fixate fewer times and for shorter durations on the provided decision aids they show more self-reported trust in. Results from this study do not indicate significant correlations between trust and eye tracking metrics; however, negative relationships are seen. Percentage splits of fixation duration and fixation count on decision aids (when compared to overall fixation data between both AOIs) rise as decision aid reliability decreases. In summary, these results support eye tracking’s potential as a real-time measurement of human trust in automation
Analytic Hierarchy Process is not a Suitable method for the Comprehensive Rating
Get PDFThe Pipeline Assessment and Certification Program (PACP) was developed by the National Association of Sewer Service Companies, the industry-accepted protocol for condition rating of sewer pipes in the US. The PACP method relies exclusively on visual inspections performed using Closed-Circuit Television (CCTV), where existing structural and operation and maintenance (O&M) defects are observed by certified operators. A limitation of the PACP method is that it does not use pipe characteristics, depth, soil type, surface conditions, pipe criticality, and capacity, nor the distribution of structural defects or history of preventative maintenance to determine the condition rating of the sewer pipe segment. Therefore, this research work addresses this limitation and develops a comprehensive rating model using Analytic Hierarchy Process(AHP) that incorporates pipe characteristics, environmental characteristics, and information about PACP structural score and PACP O&M score in hydraulic factors. Factors such as pipe age, pipe material, diameter, shape, depth, soil type, loading, type of carried waste, seismic zone, PACP structural score, and PACP O&M score are used. The results showed a below-average validity percentage because linear regression assumes a linear relationship between the input and output variables. Still, the actual relation between response and the predictor is not linear. Our proposed model is applied to the data received from the City of Shreveport, LA, which is currently under a Federal Consent Decree
Teacher Autonomy: A Multi-Site Case Study
Get PDFThe purpose of this qualitative case study was to examine teacher autonomy and practices that school leaders implement to promote teacher autonomy at three schools in a small rural town in the southern United States. The study examined how school leaders influenced teacher autonomy in the classroom. This study incorporated an instrumental case study method and determined how teachers interpret, construct, and apply meaning to the autonomy they experience in the classroom and at the school. The researcher examined how school leaders interpret, construct, and apply meaning to their roles in enabling teacher autonomy. The study implemented the transformational leadership theory. Key findings suggest that teachers value decision-making about classroom management and curriculum choice and that it is directly linked to positive levels of autonomy for educators at all three sites. Teachers shared the understanding that autonomy is having the flexibility to teach. Most participants had a strong understanding of autonomy and openly and willingly expressed their opinions