Acoustic Emissions at an Open Crack

Both finite difference and finite element techniques have been shown to be capable of modeling the propagation of acoustic emissions (AE) [1,2]. However, those calculations could also be done using the simpler Green’s function methods [3]. In this work the finite element method is used to model a problem that includes complexities that cannot be handled using the Green’s function methods

Physics of Neutron Star Kicks

It is no longer necessary to `sell' the idea of pulsar kicks, the notion that neutron stars receive a large velocity (a few hundred to a thousand km s$^{-1}$) at birth. However, the origin of the kicks remains mysterious. We review the physics of different kick mechanisms, including hydrodynamically driven, neutrino and magnetically driven kicks.Comment: 8 pages including 1 figure. To be published in "Stellar Astrophysics" (Pacific Rim Conference Proceedings), (Kluwer Pub.

Bistability in Apoptosis by Receptor Clustering

Apoptosis is a highly regulated cell death mechanism involved in many physiological processes. A key component of extrinsically activated apoptosis is the death receptor Fas, which, on binding to its cognate ligand FasL, oligomerize to form the death-inducing signaling complex. Motivated by recent experimental data, we propose a mathematical model of death ligand-receptor dynamics where FasL acts as a clustering agent for Fas, which form locally stable signaling platforms through proximity-induced receptor interactions. Significantly, the model exhibits hysteresis, providing an upstream mechanism for bistability and robustness. At low receptor concentrations, the bistability is contingent on the trimerism of FasL. Moreover, irreversible bistability, representing a committed cell death decision, emerges at high concentrations, which may be achieved through receptor pre-association or localization onto membrane lipid rafts. Thus, our model provides a novel theory for these observed biological phenomena within the unified context of bistability. Importantly, as Fas interactions initiate the extrinsic apoptotic pathway, our model also suggests a mechanism by which cells may function as bistable life/death switches independently of any such dynamics in their downstream components. Our results highlight the role of death receptors in deciding cell fate and add to the signal processing capabilities attributed to receptor clustering.Comment: Accepted by PLoS Comput Bio

Seagrass can mitigate negative ocean acidification effects on calcifying algae

The ultimate effect that ocean acidification (OA) and warming will have on the physiology of calcifying algae is still largely uncertain. Responses depend on the complex interactions between seawater chemistry, global/local stressors and species-specific physiologies. There is a significant gap regarding the effect that metabolic interactions between coexisting species may have on local seawater chemistry and the concurrent effect of OA. Here, we manipulated CO2 and temperature to evaluate the physiological responses of two common photoautotrophs from shallow tropical marine coastal ecosystems in Brazil: the calcifying alga Halimeda cuneata, and the seagrass Halodule wrightii. We tested whether or not seagrass presence can influence the calcification rate of a widespread and abundant species of Halimeda under OA and warming. Our results demonstrate that under elevated CO2, the high photosynthetic rates of H. wrightii contribute to raise H. cuneata calcification more than two-fold and thus we suggest that H. cuneata populations coexisting with H. wrightii may have a higher resilience to OA conditions. This conclusion supports the more general hypothesis that, in coastal and shallow reef environments, the metabolic interactions between calcifying and non-calcifying organisms are instrumental in providing refuge against OA effects and increasing the resilience of the more OA-susceptible species.E.B. would like to thank the Coordenação de Aperfeiçoamento de Pessoas de Nível Superior (CAPES) for Masters funding. Funding for this project came from the Synergism grant (CNPq 407365/2013-3). We extend our thanks to the Brazil-based Projeto Coral Vivo and its sponsor PetroBras Ambiental for providing the Marine Mesocosm structure and experimental assistance.info:eu-repo/semantics/publishedVersio

Tri-Modality therapy with I-125 brachytherapy, external beam radiation therapy, and short- or long-term hormone therapy for high-risk localized prostate cancer (TRIP): study protocol for a phase III, multicenter, randomized, controlled trial

<p>Abstract</p> <p>Background</p> <p>Patients with high Gleason score, elevated prostate specific antigen (PSA) level, and advanced clinical stage are at increased risk for both local and systemic relapse. Recent data suggests higher radiation doses decrease local recurrence and may ultimately benefit biochemical, metastasis-free and disease-specific survival. No randomized data is available on the benefits of long-term hormonal therapy (HT) in these patients. A prospective study on the efficacy and safety of trimodality treatment consisting of HT, external beam radiation therapy (EBRT), and brachytherapy (BT) for high-risk prostate cancer (PCa) is strongly required.</p> <p>Methods/Design</p> <p>This is a phase III, multicenter, randomized controlled trial (RCT) of trimodality with BT, EBRT, and HT for high-risk PCa (TRIP) that will investigate the impact of adjuvant HT following BT using iodine-125 (¹²⁵I-BT) and supplemental EBRT with neoadjuvant and concurrent HT. Prior to the end of September 2012, a total of 340 patients with high-risk PCa will be enrolled and randomized to one of two treatment arms. These patients will be recruited from more than 41 institutions, all of which have broad experience with ¹²⁵I-BT. Pathological slides will be centrally reviewed to confirm patient eligibility. The patients will commonly undergo 6-month HT with combined androgen blockade (CAB) before and during ¹²⁵I-BT and supplemental EBRT. Those randomly assigned to the long-term HT group will subsequently undergo 2 years of adjuvant HT with luteinizing hormone-releasing hormone agonist. All participants will be assessed at baseline and every 3 months for the first 30 months, then every 6 months until 84 months from the beginning of CAB.</p> <p>The primary endpoint is biochemical progression-free survival. Secondary endpoints are overall survival, clinical progression-free survival, disease-specific survival, salvage therapy non-adaptive interval, and adverse events.</p> <p>Discussion</p> <p>To our knowledge, there have been no prospective studies documenting the efficacy and safety of trimodality therapy for high-risk PCa. The present RCT is expected to provide additional insight regarding the potency and limitations of the addition of 2 years of adjuvant HT to this trimodality approach, and to establish an appropriate treatment strategy for high-risk PCa.</p> <p>Trial registration</p> <p>UMIN000003992</p

Do breast implants after a mastectomy affect subsequent prognosis and survival?

In a large study, published in this issue of Breast Cancer Research, Le and colleagues report that women receiving implants after mastectomies for early-stage breast cancer experience lower breast cancer mortality than women not receiving implants. Assessment of survival patterns among women receiving reconstructive implants is complex given unique patient characteristics, disease attributes, and treatment patterns. The interpretation of reduced mortality from breast cancer must be assessed in light of significantly reduced risks of death from most other causes. In contrast, patients receiving post-mastectomy implants had elevated rates of suicide, consistent with findings among women with cosmetic implants. Additional well-designed investigations are needed to clarify survival patterns among women receiving reconstructive implants

First Impressions of HIV Risk: It Takes Only Milliseconds to Scan a Stranger

Research indicates that many people do not use condoms consistently but instead rely on intuition to identify sexual partners high at risk for HIV infection. The present studies examined neural correlates for first impressions of HIV risk and determined the association of perceived HIV risk with other trait characteristics. Participants were presented with 120 self-portraits retrieved from a popular online photo-sharing community (www.flickr.com). Factor analysis of various explicit ratings of trait characteristics yielded two orthogonal factors: (1) a ‘valence-approach’ factor encompassing perceived attractiveness, healthiness, valence, and approach tendencies, and (2) a ‘safeness’ factor, entailing judgments of HIV risk, trustworthiness, and responsibility. These findings suggest that HIV risk ratings systematically relate to cardinal features of a high-risk HIV stereotype. Furthermore, event-related brain potential recordings revealed neural correlates of first impressions about HIV risk. Target persons perceived as risky elicited a differential brain response in a time window from 220–340 ms and an increased late positive potential in a time window from 350–700 ms compared to those perceived as safe. These data suggest that impressions about HIV risk can be formed in a split second and despite a lack of information about the actual risk profile. Findings of neural correlates of risk impressions and their relationship to key features of the HIV risk stereotype are discussed in the context of the ‘risk as feelings’ theory

Noisy-threshold control of cell death

<p>Abstract</p> <p>Background</p> <p>Cellular responses to death-promoting stimuli typically proceed through a differentiated multistage process, involving a lag phase, extensive death, and potential adaptation. Deregulation of this chain of events is at the root of many diseases. Improper adaptation is particularly important because it allows cell sub-populations to survive even in the continuous presence of death conditions, which results, among others, in the eventual failure of many targeted anticancer therapies.</p> <p>Results</p> <p>Here, I show that these typical responses arise naturally from the interplay of intracellular variability with a threshold-based control mechanism that detects cellular changes in addition to just the cellular state itself. Implementation of this mechanism in a quantitative model for T-cell apoptosis, a prototypical example of programmed cell death, captures with exceptional accuracy experimental observations for different expression levels of the oncogene Bcl-x_Land directly links adaptation with noise in an ATP threshold below which cells die.</p> <p>Conclusions</p> <p>These results indicate that oncogenes like Bcl-x_L, besides regulating absolute death values, can have a novel role as active controllers of cell-cell variability and the extent of adaptation.</p

Cluster Lenses

Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining to cluster formation and evolution, as well as constraining the nature of dark matter; (ii) the study of the lensed objects - probing the properties of the background lensed galaxy population - which is statistically at higher redshifts and of lower intrinsic luminosity thus enabling the probing of galaxy formation at the earliest times right up to the Dark Ages; and (iii) the study of the geometry of the Universe - as the strength of lensing depends on the ratios of angular diameter distances between the lens, source and observer, lens deflections are sensitive to the value of cosmological parameters and offer a powerful geometric tool to probe Dark Energy. In this review, we present the basics of cluster lensing and provide a current status report of the field.Comment: About 120 pages - Published in Open Access at: http://www.springerlink.com/content/j183018170485723/ . arXiv admin note: text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author

Comparison of risk-scoring systems in the prediction of outcome after liver resection

Background: Risk prediction techniques commonly used in liver surgery include the American Society of Anesthesiologists (ASA) grading, Charlson Comorbidity Index (CCI) and cardiopulmonary exercise tests (CPET). This study compares the utility of these techniques along with the number of segments resected as predictive tools in liver surgery. Methods: A review of a unit database of patients undergoing liver resection between February 2008 and January 2015 was undertaken. Patient demographics, ASA, CCI and CPET variables were recorded along with resection size. Clavien-Dindo grade III–V complications were used as a composite outcome in analyses. Association between predictive variables and outcome was assessed by univariate and multivariate techniques. Results: One hundred and seventy-two resections in 168 patients were identified. Grade III–V complications occurred after 42 (24.4%) liver resections. In univariate analysis of CPET variables, ventilatory equivalents for CO2 (VEqCO2) was associated with outcome. CCI score, but not ASA grade, was also associated with outcome. In multivariate analysis, the odds ratio of developing grade III–V complications for incremental increases in VEqCO2, CCI and number of liver segments resected were 1.09, 1.49 and 2.94, respectively. Conclusions: Of the techniques evaluated, resection size provides the simplest and most discriminating predictor of significant complications following liver surgery