In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two Centaur objects: 2014 YY49 on 2019 January 28 and 2013 NL24 on ...2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius km and a geometric albedo for 2014 YY49 and a radius km and a geometric albedo for 2013 NL24. To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two Centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two Centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects' colors and light curve amplitudes and on follow-on occultation efforts informed by this astrometry.
Neurotrauma is a general term describing injury to the central nervous system (CNS); which comprises of the brain and spinal cord. The damage resulting from neurotrauma includes primary injury, which ...occurs from different sources such as compressed air hitting the brain (bTBI) or an object/bone contusing the spinal cord, resulting in a spinal cord injury (SCI). These various means of primary brain and spinal cord injury are further complicated by the many possible combinations of severity levels and frequencies. However, primary injuries are regarded in many cases as unavoidable with the immediate nerve damage being largely irreversible. Despite all this, primary injuries of the CNS are related by common biochemical pathways in secondary injury. Secondary injury is the cause of declining outcomes after neurotrauma and poor recovery. Secondary injury begins immediately after primary injury and can continue to trigger death of neurons for years later. Given this contribution to poor recovery and its slow progression, secondary injury provides an excellent window of opportunity for therapeutic intervention. A major factor and key link in secondary injury and its perpetuation is reactive aldehyde formation, such as acrolein, from lipid peroxidation. The common formation of acrolein in neurotrauma is attributed to the unique structure of the CNS: with neurons containing a high lipid content from myelin and heavy metabolic activity they are vulnerable to acrolein formation. Thus, acrolein in secondary injury is a point of pathogenic convergence between the various forms of neurotrauma, and may play a role as well in the development of neurotrauma linked disorders and related neurodegeneration. The overall goal of this thesis is to therefore develop better strategies for acrolein removal. We explore here endogenous clearance strategies and targeted drug delivery in SCI, investigate detailed cellular structure changes in bTBI, and acrolein formation and removal in Parkinson’s disease. These findings of pathology, and effectiveness of new or existing acrolein removal strategies, will allow us to better employ treatments in future studies.
In the studies reported here, we investigate the effects of context on students' molecular-level ideas regarding aqueous solutions. During one-on-one interviews, 19 general chemistry students ...recruited from a two-year community college and a research university in the United States were asked to describe their molecular-level ideas about various aqueous solutions in the contexts of conductivity and boiling-point (BP) elevation. Results indicate that context is important for determining the molecular-level ideas that students express. Specifically, students were significantly more likely to draw pictures of aqueous NaCl as separated ions in the conductivity context compared with the BP elevation context, for which they more often drew "molecular" NaCl. This phenomenon was particularly striking because the students drew molecular-level NaCl(aq) pictures in the BP elevation context just minutes after completing the identical task in the context of conductivity. Additional data from laboratory assignments and course examinations further indicate that, even if students are able to correctly represent the molecular level in some contexts, their knowledge may remain inert in slightly different contexts. The results emphasise the importance of the context dependence of molecular-level ideas and have implications for designing instruction in which students develop robust, coherent understandings that they can apply appropriately in new contexts.
In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two centaur objects: 2014 YY\(_{49}\) on 2019 January 28 and 2013 ...NL\(_{24}\) on 2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius \(r=16^{+2}_{-1}\)km and a geometric albedo \(p_V=0.13^{+0.015}_{-0.024}\) for 2014 YY\(_{49}\), and a radius \(r=66 ^{+5}_{-5}\)km and geometric albedo \(p_V = 0.045^{+0.006}_{-0.008}\) for 2013 NL\(_{24}\). To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects' colors and light curve amplitudes, and on follow-on occultation efforts informed by this astrometry.
Part I: Students' participation in inquiry-based chemistry laboratory curricula, and, in particular, engagement with key thinking processes in conjunction with these experiences, is linked with ...success at the difficult task of "transfer"--applying their knowledge in new contexts to solve unfamiliar types of problems. We investigate factors related to classroom experiences, student metacognition, and instructor feedback that may affect students' engagement in key aspects of the Model-Observe-Reflect-Explain (MORE) laboratory curriculum-production of written molecular-level models of chemical systems, describing changes to those models, and supporting those changes with reference to experimental evidence--and related behaviors. Participation in introductory activities that emphasize reviewing and critiquing of sample models and peers' models are associated with improvement in several of these key aspects. When students' self-assessments of the quality of aspects of their models are solicited, students are generally overconfident in the quality of their models, but these self-ratings are also sensitive to the strictness of grades assigned by their instructor. Furthermore, students who produce higher-quality models are also more accurate in their self-assessments, suggesting the importance of self-evaluation as part of the model-writing process. While the written feedback delivered by instructors did not have significant impacts on student model quality or self-assessments, students' resubmissions of models were significantly improved when students received "reflective" feedback prompting them to self-evaluate the quality of their models. Analysis of several case studies indicates that the content and extent of molecular-level ideas expressed in students' models are linked with the depth of discussion and content of discussion that occurred during the laboratory period, with ideas developed or personally committed to by students during the laboratory period being likely to appear in students' post-laboratory refined models. These discussions during the laboratory period are primarily prompted by factors external to the students or their laboratory groups such as questions posed by the instructor or laboratory materials. Part II. Solvation of polar molecules within non-polar supercritical carbon dioxide is often facilitated by the introduction of polar cosolvents as entrainers, which are believed to preferentially surround solute molecules. Molecular dynamics simulations of supercritical carbon dioxide/ethanol mixtures reveal that ethanol molecules form hydrogen-bonded aggregates of varying sizes and structures, with cyclic tetramers and pentamers being unusually prevalent. The dynamics of ethanol molecules within these mixtures at a range of thermodynamic conditions can largely be explained by differences in size and structure in these aggregates. Simulations that include solute molecules reveal enhancement of the polar cosolvent around hydrogen-bonding sites on the solute molecules, corroborating and helping to explain previously reported experimental trends in solute mobility. The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.
Mercer University: Pathways to Signature Work for Nontraditional Students Mercer University's Penfield College offers undergraduate, graduate, and professional degree programs designed to serve a ...nontraditional-adult-learner and transfer-student population. Because Mercer designed Penfield specifically to serve traditionally underrepresented students, the college's undergraduate program is uniquely poised within the larger institution to adopt the STIRS framework in a way that serves what is now being recognized as the new student majority in the United States. The STIRS initiative provides a framework for the college to continue improving the capacity of undergraduate students in all fields of study to use evidence to solve problems and make decisions.\n By taking account of this need, an unanticipated-but we believe very fortuitous-outcome has emerged: a mechanism to address the needs of undeclared students who have reached junior status without a major or focus of study, and thus who find themselves at risk for a delayed graduation, or in some cases, no degree attainment at all.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two Centaur objects: 2014 YY
49
on 2019 January 28 and 2013 ...NL
24
on 2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius
km and a geometric albedo
for 2014 YY
49
and a radius
km and a geometric albedo
for 2013 NL
24
. To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two Centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two Centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects’ colors and light curve amplitudes and on follow-on occultation efforts informed by this astrometry.
DNA repair is essential for the genomic integrity of cells and organism survival. DNA damage not only causes mutation but also can result in disease and lethality through obstruction of transcription ...by RNA polymerase II stalled at DNA lesions. Transcription-coupled repair (TCR) allows for rapid removal of DNA lesions that block transcription from actively transcribed regions of the genome. RNA polymerase II (RNAPII), transcription factor IIH (TFIIH), Xeroderma Pigmentosum complementation group-G protein (XPG), and Cockayne Syndrome complementation group-B protein (CSB) have been implicated as key players in the TCR pathway. The overall objective of this work is to understand how the TCR machinery assembles and functions. To this end we have begun to define the structural characteristics of these protein complexes through biochemistry and single particle electron microscopy analysis. Human TCR proteins were purified and an in vitro transcription system was used to create artificially stalled RNAPII complexes. Electromobility shift assays (EMSA) demonstrated that stalled-RNAPII, XPG, and CSB formed a stable supra-molecular complex and sub-complexes. Further EMSA analysis with transcription reactions modified to lack the non-template DNA strand failed to form complexes between stalled RNAPII and the other TCR proteins. These findings in addition to results from our collaborators in the Cooper lab indicate that the DNA structure that RNAPII maintains during transcription is essential for TCR complex formation. As a first step toward structural analysis of the supra-molecular TCR complex the human RNAPII enzyme was analyzed by electron microscopy. Single particle reconstruction methodologies confirm that the human RNAPII is similar, though not identical, to the yeast RNAPII in overall architecture. 2-D analysis further revealed that there is conformational heterogeneity in the sample. These studies provide a platform on which we can build up higher order TCR complexes and obtain 3-D structures of these large macromolecular entities to obtain structural information and gain further insight into TCR.
The improved characterisation of risk factors for rheumatoid arthritis (RA) suggests they could be combined to identify individuals at increased disease risks in whom preventive strategies may be ...evaluated. We aimed to develop an RA prediction model capable of generating clinically relevant predictive data and to determine if it better predicted younger onset RA (YORA). Our novel modelling approach combined odds ratios for 15 four-digit/10 two-digit HLA-DRB1 alleles, 31 single nucleotide polymorphisms (SNPs) and ever-smoking status in males to determine risk using computer simulation and confidence interval based risk categorisation. Only males were evaluated in our models incorporating smoking as ever-smoking is a significant risk factor for RA in men but not women. We developed multiple models to evaluate each risk factor's impact on prediction. Each model's ability to discriminate anti-citrullinated protein antibody (ACPA)-positive RA from controls was evaluated in two cohorts: Wellcome Trust Case Control Consortium (WTCCC: 1,516 cases; 1,647 controls); UK RA Genetics Group Consortium (UKRAGG: 2,623 cases; 1,500 controls). HLA and smoking provided strongest prediction with good discrimination evidenced by an HLA-smoking model area under the curve (AUC) value of 0.813 in both WTCCC and UKRAGG. SNPs provided minimal prediction (AUC 0.660 WTCCC/0.617 UKRAGG). Whilst high individual risks were identified, with some cases having estimated lifetime risks of 86%, only a minority overall had substantially increased odds for RA. High risks from the HLA model were associated with YORA (P<0.0001); ever-smoking associated with older onset disease. This latter finding suggests smoking's impact on RA risk manifests later in life. Our modelling demonstrates that combining risk factors provides clinically informative RA prediction; additionally HLA and smoking status can be used to predict the risk of younger and older onset RA, respectively.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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