Experimentation and Modeling of Laser Radiation Scattering Through Carbon Fiber Reinforced Polymers

With the prevalence of carbon fiber reinforced polymers (CFRPs) in aerospace platforms, there is a need to better understand radiative heat transport through the material. A laboratory experiment was constructed and a computational zonal Monte Carlo (ZMC) model developed to quantify and understand the laser scattering properties of CFRPs. The ZMC model builds off of the zonal method (ZM)—developed by Hottel et al. and expanded by researchers such as Yuen et al.—by incorporating Monte Carlo techniques into the ZM. The ZMC method is superior in efficiency to the ZM and alternative ray tracing methods, which enables larger mediums of exchange to be analyzed. A laser experiment was constructed using a commercial off-the shelf 1.26 kW ytterbium fiber laser (run at 70 W in this thesis) with customized optics to focus the beam into a vacuum chamber, as well as photodiodes, thermocouples, an IR camera and pyrometer for temperature, reflection and transmissivity measurements. Transmission data were analyzed using the ZMC method to determine CFRP albedo and extinction coefficients, which can be utilized for platform-level aerospace models to predict heat transfer more accurately through CFRP structures. Specifically, these optical properties can be read into multi-physics tools such as COMSOL to better predict radiation scattering through CFRP. Matching laser radiation scattering to CFRP test data has not been done before and provides validation to optical property predictions. The effects of nodal, substrate and detector plane sizing, as well as laser beam parameters, were also studied and optimized when matching albedo and extinction coefficient predictions from the ZMC method to experimental test data. Average albedo values for IM7/977-3 CFRP using the anchored ZMC method are 0.78 and 0.81 with one-ply and two-ply samples, respectively, having standard deviations of 0.11 and 0.09. Extinction coefficient predictions are 109.4 and 93.8 cm-1 with standard deviations of 28.3 and 18.8 cm-1 for one-ply and two-ply samples. When these optical properties are incorporated into multi-physic models and scaled up to larger aerospace platforms, this increased radiation transport accuracy will lead to a better understanding of laser-material interactions and burn-through times

Fine-scale changes in speed and altitude suggest protean movements in homing pigeon flights

The power curve provides a basis for predicting adjustments that animals make in flight speed, for example in relation to wind, distance, habitat foraging quality and objective. However, relatively few studies have examined how animals respond to the landscape below them, which could affect speed and power allocation through modifications in climb rate and perceived predation risk. We equipped homing pigeons (Columba livia) with high-frequency loggers to examine how flight speed, and hence effort, varies in relation to topography and land cover. Pigeons showed mixed evidence for an energy-saving strategy, as they minimized climb rates by starting their ascent ahead of hills, but selected rapid speeds in their ascents. Birds did not modify their speed substantially in relation to land cover, but used higher speeds during descending flight, highlighting the importance of considering the rate of change in altitude before estimating power use from speed. Finally, we document an unexpected variability in speed and altitude over fine scales; a source of substantial energetic inefficiency. We suggest this may be a form of protean behaviour adopted to reduce predation risk when flocking is not an option, and that such a strategy could be widespread

Prevention Research Centers: Contributions to Updating the Public Health Workforce Through Training

Because public health is a continually evolving field, it is essential to provide ample training opportunities for public health professionals. As a natural outgrowth of the Centers for Disease Control and Prevention\u27s Prevention Research Centers Program, training courses of many types have been developed for public health practitioners working in the field. This article describes three of the Prevention Research Center training program offerings: Evidence-Based Public Health, Physical Activity and Public Health for Practitioners, and Social Marketing. These courses illustrate the commitment of the Prevention Research Centers Program to helping create a better trained public health workforce, thereby enhancing the likelihood of improving public health

First Case of Bioterrorism-Related Inhalational Anthrax in the United States, Palm Beach County, Florida, 2001

On October 4, 2001, we confirmed the first bioterrorism-related anthrax case identified in the United States in a resident of Palm Beach County, Florida. Epidemiologic investigation indicated that exposure occurred at the workplace through intentionally contaminated mail. One additional case of inhalational anthrax was identified from the index patient’s workplace. Among 1,076 nasal cultures performed to assess exposure, Bacillus anthracis was isolated from a co-worker later confirmed as being infected, as well as from an asymptomatic mail-handler in the same workplace. Environmental cultures for B. anthracis showed contamination at the workplace and six county postal facilities. Environmental and nasal swab cultures were useful epidemiologic tools that helped direct the investigation towards the infection source and transmission vehicle. We identified 1,114 persons at risk and offered antimicrobial prophylaxis

Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500

Communications Biophysics

Contains research objectives, summary of research and reports on three research projects.National Institutes of Health (Grant 5 PO1 GM14940-06)National Institutes of Health (Grant 2 TOl GM01555-06)National Institutes of Health (Grant 1 ROl NS10737-01)National Aeronautics and Space Administration (Grant NGL 22-009-304)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300B-D Electrodyne Division, Becton Dickinson and Company (Grant)Boston City Hospital Purchase Order 1176-21-33

Communications Biophysics

Contains research objectives and summary of research on thirteen research projects split into four section.National Institutes of Health (Grant 1 RO1 NS10737-01)National Institutes of Health (Grant 1 ROI NS10916-01)National Institutes of Health (Grant 5 RO1 NS11000-02)National Institutes of Health (Grant 1 RO1 NS11153-01)Harvard M.I.T. Rehabilitation Engineering CenterU. S. Department of Health, Education, and Welfare, Grant 23-P-55854National Institutes of Health (Grant 1 RO1 NS11680-01)Norlin Music, Inc.Clarence J. LeBel FundNational Institutes of Health (Grant 1 RO1 NS11080-01A1)National Institutes of Health (Grant 5 TO1 GM01555-08)M.I.T. Health Sciences FundBoston City Hospital Purchase Order 1176-05-21335-C

Human Monoclonal Antibodies to a Novel Cluster of Conformational Epitopes on HCV E2 with Resistance to Neutralization Escape in a Genotype 2a Isolate

The majority of broadly neutralizing antibodies to hepatitis C virus (HCV) are against conformational epitopes on the E2 glycoprotein. Many of them recognize overlapping epitopes in a cluster, designated as antigenic domain B, that contains residues G530 and D535. To gain information on other regions that will be relevant for vaccine design, we employed yeast surface display of antibodies that bound to genotype 1a H77C E2 mutant proteins containing a substitution either at Y632A (to avoid selecting non-neutralizing antibodies) or D535A. A panel of nine human monoclonal antibodies (HMAbs) was isolated and designated as HC-84-related antibodies. Each HMAb neutralized cell culture infectious HCV (HCVcc) with genotypes 1–6 envelope proteins with varying profiles, and each inhibited E2 binding to the viral receptor CD81. Five of these antibodies neutralized representative genotypes 1–6 HCVcc. Epitope mapping identified a cluster of overlapping epitopes that included nine contact residues in two E2 regions encompassing aa418–446 and aa611–616. Effect on virus entry was measured using H77C HCV retroviral pseudoparticles, HCVpp, bearing an alanine substitution at each of the contact residues. Seven of ten mutant HCVpp showed over 90% reduction compared to wild-type HCVpp and two others showed approximately 80% reduction. Interestingly, four of these antibodies bound to a linear E2 synthetic peptide encompassing aa434–446. This region on E2 has been proposed to elicit non-neutralizing antibodies in humans that interfere with neutralizing antibodies directed at an adjacent E2 region from aa410–425. The isolation of four HC-84 HMAbs binding to the peptide, aa434–446, proves that some antibodies to this region are to highly conserved epitopes mediating broad virus neutralization. Indeed, when HCVcc were passaged in the presence of each of these antibodies, virus escape was not observed. Thus, the cluster of HC-84 epitopes, designated as antigenic domain D, is relevant for vaccine design for this highly diverse virus

B-MYB Is Essential for Normal Cell Cycle Progression and Chromosomal Stability of Embryonic Stem Cells

Background: The transcription factor B-Myb is present in all proliferating cells, and in mice engineered to remove this gene, embryos die in utero just after implantation due to inner cell mass defects. This lethal phenotype has generally been attributed to a proliferation defect in the cell cycle phase of G1. Methodology/Principal Findings: In the present study, we show that the major cell cycle defect in murine embryonic stem (mES) cells occurs in G2/M. Specifically, knockdown of B-Myb by short-hairpin RNAs results in delayed transit through G2/M, severe mitotic spindle and centrosome defects, and in polyploidy. Moreover, many euploid mES cells that are transiently deficient in B-Myb become aneuploid and can no longer be considered viable. Knockdown of B-Myb in mES cells also decreases Oct4 RNA and protein abundance, while over-expression of B-MYB modestly up-regulates pou5f1 gene expression. The coordinated changes in B-Myb and Oct4 expression are due, at least partly, to the ability of B-Myb to directly modulate pou5f1 gene promoter activity in vitro. Ultimately, the loss of B-Myb and associated loss of Oct4 lead to an increase in early markers of differentiation prior to the activation of caspase-mediated programmed cell death. Conclusions/Significance: Appropriate B-Myb expression is critical to the maintenance of chromosomally stable and pluripotent ES cells, but its absence promotes chromosomal instability that results in either aneuploidy or differentiation-associated cell death