Direct observation of voids in the vacancy excess region of ion bombarded silicon

The results reported in this letter indicate that the spatial separation of the vacancy and interstitial excesses which result from ion bombardment gives rise to stable voids upon annealing at 850 °C even for implants where the projected ion range is only of the order of a few thousand Ångstrom. Such voids have been observed directly by transmission electron microscopy. Furthermore, in cases where both voids and interstitial-based defects are present at different depths, it is found that Au has a strong preference for decorating void surfaces and hence Au can, indeed, be used as a selective detector of open volume defects in Si.One of the authors ~J.W.-L.! acknowledges the Australian Research Council for financial support

Effects of Symbol Sets and Needs Gratifications on Audience Engagement: Contextualizing Police Social Media Communication

We propose a research model based on media synchronicity theory (MST) and examine how the use of different symbol sets (e.g., images and text) is related to audience engagement on social media. We include uses and gratifications theory (UGT) in the model to identify task characteristics that are relevant to message recipients in the specific context of community policing. Based on our analyses of Facebook posts by five police departments, we find first that, consistent with MST, posts conveying information garner more responses when accompanied by more natural symbol sets, and more textual content is preferred to less, but responses differ depending on the type of engagement: intimacy (likes), interaction (comments), or influence (shares). Second, posts intended for meaning convergence gratify the audience’s socialization and assistance needs and are positively related to intimacy and interaction. Finally, the fit between symbol sets and task characteristics impacts different dimensions of audience engagement. These findings provide empirical support for relying on MST when studying social media and for integrating with UGT to capture contextual task characteristics. We conclude the paper with a discussion of the implications of its findings for theory and offer recommendations for practice

IT\u27S WHAT YOU WRITE and HOW YOU WRITE ABOUT IT: THE POLICING FACEBOOK EXPERIENCE

This study focuses on social media use by law enforcement agencies. Based on media richness theory, we examined how the responses to Facebook messages posted by five police departments vary by type of cue, image vs. text, and across different content categories. Our findings suggest that although messages with richer information, namely more visual and verbal cues, receive more likes, topics such as Accident, Traffic and Announcement receive significantly fewer likes. Moreover, the presence of pictures in announcement messages reduces the number of likes. In addition, although people comment on messages about Property/Pets, they are much less inclined to comment on other topics. Our study contributes to media richness theory by demonstrating the importance of considering the nature and context of a communication, as represented by the content category, and to law enforcement agencies\u27 practice by offering recommendations for how to measure public engagement and design strategies that will better leverage social media

Estimation and Application of 2-D Scattering Matrices for Sparse Array Imaging of Impact Damage in Composite Panels

Reliable detection of hidden damage in composites is important for failure prevention in the aerospace industry since these materials are being more frequently used in high stress applications. Structural health monitoring (SHM) via guided wave sensors mounted on or embedded within a composite structure can help detect and localize damage in real-time while also reducing overall maintenance costs. One approach to guided wave SHM is sparse array imaging via the minimum variance algorithm, and it has been shown in prior work that incorporating estimated scattering from expected defects can improve the quality of damage localization and characterization [1]. For this study, impacts were applied to induce delaminations within a composite panel. Wavefield data were recorded on a circle centered at the damage location from multiple incident directions before and after the impacts. Baseline subtraction [2] is used to estimate scattering patterns for each incident direction, and these patterns are combined and interpolated to form a full 2-D scattering matrix. This matrix is then incorporated into the minimum variance imaging algorithm, and imaging efficacy is evaluated for both these impacts and impact damage in other similar composite plates. Results are compared to images generated using simpler scattering assumptions

Multiple prebiotic metals mediate translation.

Today, Mg2+ is an essential cofactor with diverse structural and functional roles in life's oldest macromolecular machine, the translation system. We tested whether ancient Earth conditions (low O2, high Fe2+, and high Mn2+) can revert the ribosome to a functional ancestral state. First, SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) was used to compare the effect of Mg2+, Fe2+, and Mn2+ on the tertiary structure of rRNA. Then, we used in vitro translation reactions to test whether Fe2+ or Mn2+ could mediate protein production, and quantified ribosomal metal content. We found that (i) Mg2+, Fe2+, and Mn2+ had strikingly similar effects on rRNA folding; (ii) Fe2+ and Mn2+ can replace Mg2+ as the dominant divalent cation during translation of mRNA to functional protein; and (iii) Fe and Mn associate extensively with the ribosome. Given that the translation system originated and matured when Fe2+ and Mn2+ were abundant, these findings suggest that Fe2+ and Mn2+ played a role in early ribosomal evolution

Evaluating Pedagogy and Practice of Universal Design for Learning in Public Schools

How can education change to meet the demands of effectively educating an increasingly diverse student population with the skills, knowledge, and abilities they need to be productive and successful citizens in the 21st century? One possible solution is to create classrooms, teachers, and schools that embrace the progressive and inclusive practices espoused by Universal Design for Learning (UDL). In addition to being rooted in UDL pedagogy, classrooms designed to meet the challenge of 21st century education need to substantially integrate and utilize advances in technology. The vanguard of literature to date in UDL could be characterized as rhetorical advocacy. That is, UDL literature is in the early stages of introducing and promoting UDL pedagogy, but to date there is not a research base strong enough to establish UDL as a scientifically validated intervention (Edyburn, 2010). UDL might sound like a good idea, but until the research base turns the corner from advocating to assessing and measuring UDL outcomes, the promise of this approach will not be realized. This article describes a study exploring effects and outcomes of a professional development program on the perceptions and practice of UDL principles in K–12 public school inclusive classrooms, and could be one step toward bridging the gap from a good idea to a solidified best practice. Specifically, this study investigated a professional development program’s effect on teachers’ perceptions, conceptualizations, and implementation of UDL principles and practice in their classrooms

Differences in reef fish assemblages between populated and remote reefs spanning multiple archipelagos across the central and western Pacific

Comparable information on the status of natural resources across large geographic and human impact scales provides invaluable context to ecosystem-based management and insights into processes driving differences among areas. Data on fish assemblages at 39 US flag coral reef-areas distributed across the Pacific are presented. Total reef fish biomass varied by more than an order of magnitude: lowest at densely-populated islands and highest on reefs distant from human populations. Remote reefs (<50 people within 100 km) averaged ~4 times the biomass of “all fishes” and 15 times the biomass of piscivores compared to reefs near populated areas. Greatest within-archipelagic differences were found in Hawaiian and Mariana Archipelagos, where differences were consistent with, but likely not exclusively driven by, higher fishing pressure around populated areas. Results highlight the importance of the extremely remote reefs now contained within the system of Pacific Marine National Monuments as ecological reference areas

Determinants of polyp Size in patients undergoing screening colonoscopy

<p>Abstract</p> <p>Background</p> <p>Pre-existing polyps, especially large polyps, are known to be the major source for colorectal cancer, but there is limited available information about factors that are associated with polyp size and polyp growth. We aim to determine factors associated with polyp size in different age groups.</p> <p>Methods</p> <p>Colonoscopy data were prospectively collected from 67 adult gastrointestinal practice sites in the United States between 2002 and 2007 using a computer-generated endoscopic report form. Data were transmitted to and stored in a central data repository, where all asymptomatic white (n = 78352) and black (n = 4289) patients who had a polyp finding on screening colonoscopy were identified. Univariate and multivariate analysis of age, gender, performance site, race, polyp location, number of polyps, and family history as risk factors associated with the size of the largest polyp detected at colonoscopy.</p> <p>Results</p> <p>In both genders, size of the largest polyp increased progressively with age in all age groups (<it>P </it>< .0001). In subjects ≥ 80 years the relative risk was 1.55 (95% CI, 1.35-1.79) compared to subjects in the youngest age group. With the exception of family history, all study variables were significantly associated with polyp size (<it>P </it>< .0001), with multiple polyps (≥ 2 versus 1) having the strongest risk: 3.41 (95% CI, 3.29-3.54).</p> <p>Conclusions</p> <p>In both genders there is a significant increase in polyp size detected during screening colonoscopy with increasing age. Important additional risk factors associated with increasing polyp size are gender, race, polyp location, and number of polyps, with polyp multiplicity being the strongest risk factor. Previous family history of bowel cancer was not a risk factor.</p

Brief psychotherapy for depression: a systematic review and meta-analysis

Objective: Because evidence-based psychotherapies of 12 to 20 sessions can be perceived as too lengthy and time intensive for the treatment of depression in primary care, a number of studies have examined abbreviated psychotherapy protocols. The purpose of this study was to conduct a systematic review and meta-analysis to determine the efficacy of brief psychotherapy (i.e., < 8 sessions) for depression. Methods: We used combined literature searches in PubMed, EMBASE, PsycINFO, and an Internet-accessible database of clinical trials of psychotherapy to conduct two systematic searches: one for existing systematic reviews and another for randomized controlled trials (RCTs). Included studies examined evidence-based psychotherapy(s) of eight or fewer sessions, focused on adults with depression, contained an acceptable control condition, were published in English, and used validated measures of depressive symptoms. Results: We retained 2 systematic reviews and 15 RCTs evaluating cognitive behavioral therapy, problem-solving therapy, and mindfulness-based cognitive therapy. The systematic reviews found brief psychotherapies to be more efficacious than control, with effect sizes ranging from −0.33 to −0.25. Our meta-analysis found six to eight sessions of cognitive behavioral therapy to be more efficacious than control (ES −0.42, 95% CI −0.74 to −0.10, I2 = 56%). A sensitivity analysis controlled for statistical heterogeneity but showed smaller treatment effects (ES −0.24, 95% CI −0.42 to −0.06, I2 = 0%). Conclusions: Depression can be efficaciously treated with six to eight sessions of psychotherapy, particularly cognitive behavioral therapy and problem-solving therapy. Access to non-pharmacologic treatments for depression could be improved by training healthcare providers to deliver brief psychotherapies

Electrogenic Na/HCO3 Cotransporter (NBCe1) Variants Expressed in Xenopus Oocytes: Functional Comparison and Roles of the Amino and Carboxy Termini

Using pH- and voltage-sensitive microelectrodes, as well as the two-electrode voltage-clamp and macropatch techniques, we compared the functional properties of the three NBCe1 variants (NBCe1-A, -B, and -C) with different amino and/or carboxy termini expressed in Xenopus laevis oocytes. Oocytes expressing rat brain NBCe1-B and exposed to a CO2/HCO3− solution displayed all the hallmarks of an electrogenic Na+/HCO3− cotransporter: (a) a DIDS-sensitive pHi recovery following the initial CO2-induced acidification, (b) an instantaneous hyperpolarization, and (c) an instantaneous Na+-dependent outward current under voltage-clamp conditions (−60 mV). All three variants had similar external HCO3− dependencies (apparent KM of 4–6 mM) and external Na+ dependencies (apparent KM of 21–36 mM), as well as similar voltage dependencies. However, voltage-clamped oocytes (−60 mV) expressing NBCe1-A exhibited peak HCO3−-stimulated NBC currents that were 4.3-fold larger than the currents seen in oocytes expressing the most dissimilar C variant. Larger NBCe1-A currents were also observed in current–voltage relationships. Plasma membrane expression levels as assessed by single oocyte chemiluminescence with hemagglutinin-tagged NBCs were similar for the three variants. In whole-cell experiments (Vm = −60 mV), removing the unique amino terminus of NBCe1-A reduced the mean HCO3−-induced NBC current 55%, whereas removing the different amino terminus of NBCe1-C increased the mean NBC current 2.7-fold. A similar pattern was observed in macropatch experiments. Thus, the unique amino terminus of NBCe1-A stimulates transporter activity, whereas the different amino terminus of the B and C variants inhibits activity. One or more cytosolic factors may also contribute to NBCe1 activity based on discrepancies between macropatch and whole-cell currents. While the amino termini influence transporter function, the carboxy termini influence plasma membrane expression. Removing the entire cytosolic carboxy terminus of NBCe1-C, or the different carboxy terminus of the A/B variants, causes a loss of NBC activity due to low expression at the plasma membrane