On the Formation of Multiple-Shells Around Asymptotic Giant Branch Stars

Two types of models for the formation of semi-periodic concentric multiple shells (M-shells) around asymptotic giant branch (AGB) stars and in planetary nebulae are compared against observations. Models that attribute the M-shells to processes in an extended wind acceleration zone around AGB stars result in an optically thick acceleration zone, which reduces the acceleration efficiency in outer parts of the extended acceleration zone. This makes such models an unlikely explanation for the formation of M-shells. Models which attribute the M-shell to semi-periodic variation in one or more stellar properties are most compatible with observations. The only stellar variation models on time scales of 50-1500 years that have been suggested are based on an assumed solar-like magnetic cycle. Although ad-hoc, the magnetic cycle assumption fits naturally into the increasingly popular view that magnetic activity plays a role in shaping the wind from upper AGB stars.Comment: 8 pages, Submitted to Ap

Does attending a charter school Reduce the likelihood of being placed into special education? Evidence from Denver, Colorado

We use administrative data to measure whether attending a charter school in Denver, Colorado, reduces the likelihood that students are newly classified as having a disability in primary grades. We employ an observational approach that takes advantage of Denver’s Common Enrollment System, which allows us to observe each school that the student listed a preference to attend. We find evidence that attending a Denver charter school reduces the likelihood that a student is classified as having a specific learning disability, which is the largest and most subjectively diagnosed disability category. We find no evidence that charter attendance reduces the probability of being classified as having a speech or language disability or autism, which are two more objectively diagnosed classifications.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding for this research came from The Searle Freedom Trust. (The Searle Freedom Trust)http://sites.bu.edu/marcuswinters/files/2017/09/Does-Charter-Attendence-Reduce-Likelihood-of-SPED-Placement.pdfhttp://sites.bu.edu/marcuswinters/files/2017/09/Does-Charter-Attendence-Reduce-Likelihood-of-SPED-Placement.pdfAccepted manuscrip

Are low-performing students more likely to exit charter schools? Evidence from New York City and Denver, Colorado

A common criticism of charter schools is that they systematically remove or “counsel out” their lowest performing students. However, relatively little is currently known about whether low-performing students are in fact more likely to exit charter schools than surrounding traditional public schools. We use longitudinal student-level data from two large urban school systems that prior research has found to have effective charter school sectors–New York City and Denver, Colorado–to evaluate whether there is a differential relationship between low-performance on standardized test scores and the probability that students exit their schools by sector attended. We find no evidence of a differential relationship between prior performance and the likelihood of exiting a school by sector. Low-performing students in both cities are either equally likely or less likely to exit their schools than are student in traditional public schools.We would like to thank the Denver Public School System for providing the data necessary for this paper, and we especially appreciated the assistance of Josh Drake, Yu-lu Hsiung, and Alisha Anuscencion. Funding for this project comes from the Searle Charitable Trust. We thank the Foundation for its support, but acknowledge that the findings and conclusions presented are our own and do not necessarily represent those of the Foundation. All remaining errors are our own. (Searle Charitable Trust)http://sites.bu.edu/marcuswinters/files/2017/09/Exiting-Charter-Schools.pdfAccepted manuscrip

Laser spectroscopy of hyperfine structure in highly-charged ions: a test of QED at high fields

An overview is presented of laser spectroscopy experiments with cold, trapped, highly-charged ions, which will be performed at the HITRAP facility at GSI in Darmstadt (Germany). These high-resolution measurements of ground state hyperfine splittings will be three orders of magnitude more precise than previous measurements. Moreover, from a comparison of measurements of the hyperfine splittings in hydrogen- and lithium-like ions of the same isotope, QED effects at high electromagnetic fields can be determined within a few percent. Several candidate ions suited for these laser spectroscopy studies are presented.Comment: 5 pages, 1 figure, 1 table. accepted for Canadian Journal of Physics (2006

Dust-forming molecules in VY Canis Majoris (and Betelgeuse)

The formation of inorganic dust in circumstellar environments of evolved stars is poorly understood. Spectra of molecules thought to be most important for the nucleation, i.e. AlO, TiO, and TiO2, have been recently detected in the red supergiant VY CMa. These molecules are effectively formed in VY CMa and the observations suggest that non-equilibrium chemistry must be involved in their formation and nucleation into dust. In addition to exploring the recent observations of VY CMa, we briefly discuss the possibility of detecting these molecules in the dust-poor circumstellar environment of Betelgeuse.Comment: contribution to Betelgeuse Workshop 2012: "The physics of Red Supergiants: recent advances and open questions", 26-29 Nov 2012 Paris (France

Stimulation with Peptidoglycan induces interleukin 6 and TLR2 expression and a concomitant downregulation of expression of adiponectin receptors 1 and 2 in 3T3-L1 adipocytes

<p>Abstract</p> <p>Background</p> <p>Inflammation is a major component of obesity and diabetes, and toll-like receptors (TLRs) play critical roles in the regulation of inflammation and response to pathogen associated molecular patterns (PAMPs) and fatty acids in. Although immune cells such as macrophages are primarily responsible for recognition and clearance of pathogens, adipocytes are also closely involved in the regulation of innate immunity and inflammation. Whereas it has been demonstrated that adipocytes respond to TLR4 stimulation with lipopolysacccharide, very little is known about their response to the TLR2 agonist, peptidoglycan.</p> <p>Methods</p> <p>We investigated the response to peptidoglycan from <it>Staphylococcus aureus </it>in differentiated 3T3-L1 adipocytes. Real-time PCR analysis was used to quantify the expression of interleukin 6 (IL6), adiponectin receptors (adipoR1 and adipoR2), toll-like receptor 2 (TLR2) and 4 (TLR2 4). Media level of IL6 was determined with ELISA.</p> <p>Results</p> <p>Adipocyte stimulation peptidoglycan induces IL6 expression (P < 0.01). Both siRNA mediated suppression of TLR2 and immunoneutralization of TLR2 with a TLR2 specific antibody inhibited response to peptidoglycan (P < 0.05). We also examined the regulation of TLR2 and TLR4 mRNA in peptidoglycan treated cells. Both peptidoglycan and lipopolysaccharide (LPS) robustly induce TLR2 mRNA expression, whereas TLR4 mRNA is weakly induced by LPS only (P < 0.05). Additionally, peptidoglycan downregulates the mRNA expression of adiponectin receptors, adipoR1 and adipoR2 (P < 0.05).</p> <p>Conclusion</p> <p>Obesity and type 2 diabetes are associated with increased expression of TLR2, this receptor could play a significant but previously unrecognized role in the establishment of chronic inflammation in adipose tissue in obesity.</p

Photo-disintegration cross section measurements on 186^{186}W, 187^{187}Re and 188^{188}Os: Implications for the Re-Os cosmochronology

Cross sections of the $^{186}$W, $^{187}$Re, $^{188}$Os($\gamma,n$) reactions were measured using quasi-monochromatic photon beams from laser Compton scattering (LCS) with average energies from 7.3 to 10.9 MeV. The results are compared with the predictions of Hauser-Feshbach statistical calculations using four different sets of input parameters. In addition, the inverse neutron capture cross sections were evaluated by constraining the model parameters, especially the $E1$ strength function, on the basis of the experimental data. The present experiment helps to further constrain the correction factor $F_{\sigma}$ for the neutron capture on the 9.75 keV state in $^{187}$Os. Implications of $F_{\sigma}$ to the Re-Os cosmochronology are discussed with a focus on the uncertainty in the estimate of the age of the Galaxy.Comment: 11 page

A Descriptive Analysis of the Appropriate Use of Cognitive Bias Terminology in Forensic Science Literature

Cognitive bias occurs without a person’s awareness and can affect decision-making abilities. In forensic science, bias can be especially detrimental to making accurate decisions about the evidence in a criminal investigation. There are many academic studies in identifying, describing, and suggesting ways to mitigate cognitive biases in forensic science. Many authors will give a known cognitive science concept a new name or create their own bias. This is a problem in the literature because nobody knows for sure how many published studies are referring to or testing the same phenomena since authors are using different definitions or terminology to describe the same concept. This study systematically identified bias terms that different domains of research use when conducting forensic science research. After identifying the bias term(s) used in each study, each error was categorized by domain (e.g., psychologists, lawyers, forensic scientists), by type of bias (e.g., confirmation bias, anchoring bias, made up bias term) and how the authors define the bias term (i.e., correct definition, incorrect definition, no definition, or made a new definition). Overall, this study shows that authors were more likely to use a correct bias term and bias definition (29%) than make up a bias term and bias definition (25%.) A majority of the authors in this study are not cognitive scientists and, therefore, are not heavily trained in cognitive terminology. The issue of the incorrect use of cognitive bias terminology is a serious one for forensic science and has yet to be noted or investigated until this preliminary analysis. The responsibility for forensic scientists who are not trained in cognitive science to understand the bias literature and to adopt the correct terminology is fundamental for proper communication among scientific professionals