X-ray CT analysis after blast of composite sandwich panels

Four composite sandwich panels with either single density or graded density foam cores and different face-sheet materials were subjected to full-scale underwater blast testing. The panels were subjected to 1kg PE4 charge at a stand-off distance of 1 m. The panel with graded density core and carbon fiber face-sheets had the lowest deflection. Post-blast damage assessment was carried out using X-ray CT scanning. The damage assessment revealed that there is a trade-off between reduced panel deflection and panel damage. This research has been performed as part of a program sponsored by the Office of Naval Research (ONR)

Sensing using differential surface plasmon ellipsometry

Copyright © 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics 96 (2004) and may be found at http://link.aip.org/link/?JAPIAU/96/3004/1In this work a differential ellipsometric method utilizing surface plasmons (SPs) for monitoring refractive index changes, which could be used in chemical and biological sensors, is presented. The method is based upon determining the azimuth of elliptically polarized light reflected from a Kretschmann SP system, resulting from linearly polarized light containing both p and s components incident upon it. The sensitivity of this azimuth to the refractive index of a dielectric on the nonprism side of the metal film is demonstrated both experimentally and theoretically. The smallest refractive index change which is resolvable is of the order of 10–7 refractive index units, although it is believed that this could be improved upon were it not for experimental constraints due to atmospheric changes and vibrations. The method requires the Kretschmann configuration to be oriented at a fixed angle, and the SP to be excited at a fixed wavelength. With no moving parts this method would be particularly robust from an application point of view

Ergodic directions for billiards in a strip with periodically located obstacles

We study the size of the set of ergodic directions for the directional billiard flows on the infinite band $\R\times [0,h]$ with periodically placed linear barriers of length $0<\lambda<h$. We prove that the set of ergodic directions is always uncountable. Moreover, if $\lambda/h\in(0,1)$ is rational the Hausdorff dimension of the set of ergodic directions is greater than 1/2. In both cases (rational and irrational) we construct explicitly some sets of ergodic directions.Comment: The article is complementary to arXiv:1109.458

Elastic Scattering and Direct Detection of Kaluza-Klein Dark Matter

Recently a new dark matter candidate has been proposed as a consequence of universal compact extra dimensions. It was found that to account for cosmological observations, the masses of the first Kaluza-Klein modes (and thus the approximate size of the extra dimension) should be in the range 600-1200 GeV when the lightest Kaluza-Klein particle (LKP) corresponds to the hypercharge boson and in the range 1 - 1.8 TeV when it corresponds to a neutrino. In this article, we compute the elastic scattering cross sections between Kaluza-Klein dark matter and nuclei both when the lightest Kaluza-Klein particle is a KK mode of a weak gauge boson, and when it is a neutrino. We include nuclear form factor effects which are important to take into account due to the large LKP masses favored by estimates of the relic density. We present both differential and integrated rates for present and proposed Germanium, NaI and Xenon detectors. Observable rates at current detectors are typically less than one event per year, but the next generation of detectors can probe a significant fraction of the relevant parameter space.Comment: 23 pages, 11 figures; v2,v3: Ref. added, discussion improved, conclusions unchanged. v4: Introduction was expanded to be more appropriate for non experts. Various clarifications added in the text. Version to be published in New Journal of Physic

Hydrocortisone, Vitamin C and Thiamine for the Treatment of Severe Sepsis and Septic Shock: A Retrospective Before-After Study

BACKGROUND: The global burden of sepsis is estimated as 15 to 19 million cases annually with a mortality rate approaching 60% in low income countries. METHODS: In this retrospective before-after clinical study, we compared the outcome and clinical course of consecutive septic patients treated with intravenous vitamin C, hydrocortisone and thiamine during a 7-month period (treatment group) compared to a control group treated in our ICU during the preceding 7 months. The primary outcome was hospital survival. A propensity score was generated to adjust the primary outcome. FINDINGS: There were 47 patients in both treatment and control groups with no significant differences in baseline characteristics between the two groups. The hospital mortality was 8.5% (4 of 47) in the treatment group compared to 40.4% (19 of 47) in the control group (p \u3c 0.001). The propensity adjusted odds of mortality in the patients treated with the vitamin C protocol was 0.13 (95% CI 0.04-0.48, p=002). The SOFA score decreased in all patients in the treatment group with none developing progressive organ failure. Vasopressors were weaned off all patients in the treatment group, a mean of 18.3 +/- 9.8 hours after starting treatment with vitamin C protocol. The mean duration of vasopressor use was 54.9 +/- 28.4 hours in the control group (p\u3c0.001). CONCLUSION: Our results suggest that the early use of intravenous vitamin C, together with corticosteroids and thiamine may prove to be effective in preventing progressive organ dysfunction including acute kidney injury and reducing the mortality of patients with severe sepsis and septic shock. Additional studies are required to confirm these preliminary findings

Behavioral Risk Elicits Selective Activation of the Executive System in Adolescents: Clinical Implications

We investigated adolescent brain processing of decisions under conditions of varying risk, reward, and uncertainty. Adolescents (n = 31) preformed a Decision–Reward Uncertainty task that separates decision uncertainty into behavioral and reward risk, while they were scanned using functional magnetic resonance imaging. Behavioral risk trials involved uncertainty about which action to perform to earn a fixed monetary reward. In contrast, during reward risk the decision that might lead to a reward was known, but the likelihood of earning a reward was probabilistically determined. Behavioral risk trials evoked greater activation than the reward risk and no risk conditions in the anterior cingulate, medial frontal gyrus, bilateral frontal poles, bilateral inferior parietal lobe, precuneus, bilateral superior-middle frontal gyrus, inferior frontal gyrus, and insula. Our results were similar to those of young adults using the same task (Huettel, 2006) except that adolescents did not show significant activation in the posterior supramarginal gyrus during behavioral risk. During the behavioral risk condition regardless of reward outcome, overall mean frontal pole activity showed a positive correlation with age during the behavioral and reward risk conditions suggesting a developmental difference of this region of interest. Additionally, reward response to the Decision–Reward Uncertainty task in adolescents was similar to that seen in young adults (Huettel, 2006). Our data did not show a correlation between age and mean ventral striatum activity during the three conditions. While our results came from a healthy high functioning non-maltreated sample of adolescents, this method can be used to address types of risks and reward processing in children and adolescents with predisposing vulnerabilities and add to the paucity of imaging studies of risk and reward processing during adolescence

Heterogeneity in tumor chromatin-doxorubicin binding revealed by in vivo fluorescence lifetime imaging confocal endomicroscopy

We present an approach to quantify drug-target engagement using in vivo fluorescence endomicroscopy, validated with in vitro measurements. Doxorubicin binding to chromatin changes the fluorescence lifetime of histone-GFP fusions that we measure in vivo at single-cell resolution using a confocal laparo/endomicroscope. We measure both intra- and inter-tumor heterogeneity in doxorubicin chromatin engagement in a model of peritoneal metastasis of ovarian cancer, revealing striking variation in the efficacy of doxorubicin-chromatin binding depending on intra-peritoneal or intravenous delivery. Further, we observe significant variations in doxorubicin-chromatin binding between different metastases in the same mouse and between different regions of the same metastasis. The quantitative nature of fluorescence lifetime imaging enables direct comparison of drug-target engagement for different drug delivery routes and between in vitro and in vivo experiments. This uncovers different rates of cell killing for the same level of doxorubicin binding in vitro and in vivo