Fractoluminescence characterization of the energy dissipated during fast fracture of glass

Fractoluminescence experiments are performed on two kinds of silicate glasses. All the light spectra collected during dynamic fracture reveal a black body radiator behaviour, which is interpreted as a crack velocity-dependent temperature rise close to the crack tip. Crack velocities are estimated to be of the order of 1300 m.s$^{-1}$ and fracture process zones are shown to extend over a few nanometers.Comment: Accepted for publication in Europhysics Letters; 5 pages; 4 figure

Evidence of Deep Water Penetration in Silica during Stress Corrosion Fracture

We measure the thickness of the heavy water layer trapped under the stress corrosion fracture surface of silica using neutron reflectivity experiments. We show that the penetration depth is 65–85 Å, suggesting the presence of a damaged zone of ~100 Å extending ahead of the crack tip during its propagation. This estimate of the size of the damaged zone is compatible with other recent results

Validity, Significance, Strengths, Limitations, and Evidentiary Value of Real-World Clinical Data for Combination Therapy in Alzheimer's Disease: Comparison of Efficacy and Effectiveness Studies

Background: Randomized controlled efficacy trials (RCTs), the scientific gold standard, are required for regulatory approval of Alzheimer's disease (AD) interventions, yet provide limited information regarding real-world therapeutic effectiveness. Objective: To compare the nature of evidence regarding the combination of approved AD treatments from RCTs versus long-term observational controlled studies (LTOCs). Methods: Comparisons of strengths, limitations, and evidence level for monotherapy [cholinesterase inhibitor (ChEI) or memantine] and combination therapy (ChEI + memantine) in RCTs versus LTOCs. Results: RCTs examined highly selected populations over months. LTOCs collected data across multiple AD stages in large populations over many years. RCTs and LTOCs show similar patterns favoring combination over monotherapy over placebo/no treatment. Long-term combination therapy compared to monotherapy reduced cognitive and functional decline and delayed time to nursing home admission. Persistent treatment was associated with slower decline. While LTOCs used control groups, adjusted for multiple covariates, had higher external validity, and favorable ethical, practical and cost considerations, their limitations included potential selection bias due to lack of placebo comparisons and randomization. Conclusions: Naturalistic LTOCs provide complementary long-term level II evidence to complement level I evidence from short-term RCTs regarding therapeutic effectiveness in AD that may otherwise be unobtainable. A coordinated strategy/consortium to pool LTOC data from multiple centers to estimate long-term comparative effectiveness, risks/benefits, and costs of AD treatments is needed

Qualitative extension of the EC′ Zone Diagram to a molecular catalyst for a multi-electron, multi-substrate electrochemical reaction

Traverse the EC′ Zone Diagram with a molecular H 2 -evolving electrocatalyst through systematic variation of the acid p K a , scan rate, acid concentration and catalyst concentration

Human cancers over express genes that are specific to a variety of normal human tissues

We have analyzed gene expression data from 3 different kinds of samples: normal human tissues, human cancer cell lines and leukemic cells from lymphoid and myeloid leukemia pediatric patients. We have searched for genes that are over expressed in human cancer and also show specific patterns of tissue-dependent expression in normal tissues. Using the expression data of the normal tissues we identified 4346 genes with a high variability of expression, and clustered these genes according to their relative expression level. Of 91 stable clusters obtained, 24 clusters included genes preferentially expressed either only in hematopoietic tissues or in hematopoietic and 1-2 other tissues; 28 clusters included genes preferentially expressed in various non-hematopoietic tissues such as neuronal, testis, liver, kidney, muscle, lung, pancreas and placenta. Analysis of the expression levels of these 2 groups of genes in the human cancer cell lines and leukemias, identified genes that were highly expressed in cancer cells but not in their normal counterparts, and were thus over expressed in the cancers. The different cancer cell lines and leukemias varied in the number and identity of these over expressed genes. The results indicate that many genes that are over expressed in human cancer cells are specific to a variety of normal tissues, including normal tissues other than those from which the cancer originated. It is suggested that this general property of cancer cells plays a major role in determining the behavior of the cancers, including their metastatic potential.Comment: To appear in PNA

Inelastic interaction mean free path of negative pions in tungsten

The inelastic interaction mean free paths lambda of 5, 10, and 15 GeV/c pions were measured by determining the distribution of first interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi2 distribution is used to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy was observed. In tungsten, lambda for pions is 206 plus or minus 6 g/sq cm

The Correlation between X-Ray Line Ionization and Optical Spectral Types of the OB Stars

Marked correlations are reported between the ionization of the X-ray line spectra of normal OB stars, as observed by the Chandra X-Ray Observatory, and their optical spectral types. These correlations include the progressive weakening of the higher ionization relative to the lower ionization X-ray lines with advancing spectral type, and the similarly decreasing intensity ratios of the H-like to He-like lines of the alpha ions. These relationships were not predicted by models, nor have they been clearly evident in astrophysical studies of a few objects; rather, they have emerged from morphological analysis of an adequate (albeit still small) sample, from which known peculiar objects such as magnetic stars and very rapid rotators have been isolated to reveal the normal trends. This process is analogous to that which first demonstrated the strong relationships between the UV wind profiles and the optical spectral types of normal OB stars, which likely bear a physical as well as a historical connection to the present X-ray results. Since the optical spectral types are calibrated in terms of fundamental stellar parameters, it follows that the winds and X-ray spectra are determined by the latter. These observations provide strong guidance for further astrophysical modeling of these phenomena.Comment: 19 pages, 7 figures, 2 tables; ApJ accepte

A Multi-Compartment, Single and Multiple Dose Pharmacokinetic Study of the Vaginal Candidate Microbicide 1% Tenofovir Gel

Background: Tenofovir (TFV) gel is being evaluated as a microbicide with pericoital and daily regimens. To inhibit viral replication locally, an adequate concentration in the genital tract is critical. Methods and Findings: Forty-nine participants entered a two-phase study: single-dose (SD) and multi-dose (MD), were randomized to collection of genital tract samples (endocervical cells [ECC], cervicovaginal aspirate and vaginal biopsies) at one of seven time points [0.5, 1, 2, 4, 6, 8, or 24 hr(s)] post-dose following SD exposure of 4 mL 1% TFV gel and received a single dose. Forty-seven were randomized to once (QD) or twice daily (BID) dosing for 2 weeks and to collection of genital tract samples at 4, 8 or 24 hrs after the final dose, but two discontinued prior to gel application. Blood was collected during both phases at the seven times post-dose. TFV exposure was low in blood plasma for SD and MD; median C max was 4.0 and 3.4 ng/mL, respectively (C≤29 ng/mL). TFV concentrations were high in aspirates and tissue after SD and MD, ranging from 1.2×10 4 to 9.9×10 6 ng/mL and 2.1×10 2 to 1.4×10 6 ng/mL, respectively, and did not noticeably differ between proximal and distal tissue. TFV diphosphate (TFV-DP), the intracellular active metabolite, was high in ECC, ranging from 7.1×10 3 to 8.8×10 6 ng/mL. TFV-DP was detectable in approximately 40% of the tissue samples, ranging from 1.8×10 2 to 3.5×10 4 ng/mL. AUC for tissue TFV-DP was two logs higher after MD compared to SD, with no noticeable differences when comparing QD and BID. Conclusions: Single-dose and multiple-dose TFV gel exposure resulted in high genital tract concentrations for at least 24 hours post-dose with minimal systemic absorption. These results support further study of TFV gel for HIV prevention. Trial registration: ClinicalTrials.gov NCT00561496. © 2011 Schwartz et al