6,680 research outputs found
Effect of Temperature on Development Rate and Survival of \u3ci\u3eNomophila Nearctica\u3c/i\u3e (Lepidoptera: Pyralidae)
Development of Nomophila nearctica was studied under six constant tempera- tures in controlled temperature cabinets. Developmental threshold temperatures for egg, larval, and prepupal-pupal stages were 8.9, 1l.5, and 9.2°C. The overall mean developmental threshold temperature for all stages was 9.9°C. Degree-day summa- tions, based on the above threshold temperatures, averaged 50, 304, and 181 DD for the egg, larval, and prepupal-pupal stages, respectively. Total heat units of 535 DD are required for development from oviposition to adult emergence. Head capsule measurements indicated six larval instars
I Know Why You Went to the Clinic: Risks and Realization of HTTPS Traffic Analysis
Revelations of large scale electronic surveillance and data mining by
governments and corporations have fueled increased adoption of HTTPS. We
present a traffic analysis attack against over 6000 webpages spanning the HTTPS
deployments of 10 widely used, industry-leading websites in areas such as
healthcare, finance, legal services and streaming video. Our attack identifies
individual pages in the same website with 89% accuracy, exposing personal
details including medical conditions, financial and legal affairs and sexual
orientation. We examine evaluation methodology and reveal accuracy variations
as large as 18% caused by assumptions affecting caching and cookies. We present
a novel defense reducing attack accuracy to 27% with a 9% traffic increase, and
demonstrate significantly increased effectiveness of prior defenses in our
evaluation context, inclusive of enabled caching, user-specific cookies and
pages within the same website
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An inspection of measurement error inherited in time-varying latent covariate proxies within marginal structural models
In longitudinal studies, the estimation of the average treatment effect from time varying treatment assumes that all covariates are measured without error within the potential outcomes framework. However, this assumption is rarely met in social science literature. Time varying latent covariates represent unobserved variables which can be incorporated in Marginal Structural Models and Propensity Score estimation through proxies (e.g., indicators and factors scores) to account for confounding on the causal effect of treatment. Traditionally, applied statisticians could use a factor score generated under statistical assumptions (e.g., composite sum score, regression factor score) as latent covariate proxies when estimating treatment effect.
Where some research has consistently shown differences between the different factor score generating methods (Rakyov, 2012); a general consensus has found that there is little to no difference between these methods (Whittaker, 2020). Recently, there has been development of a factor score estimated under causal inference assumptions (i.e., the exposure confounder joint distribution) called the inclusive factor score (Nguyen & Stuart, 2020). This new causally generated factor score has been shown to outperform and mitigate the inherit measurement error found in latent covariate proxies. However, this leaves a gap in the literature as the research is confined to time-fixed treatment alone with no recommendations on best practices for the inclusion of multiple exposure variables. Thus, a systematic review and examination of latent covariate proxies, time-varying treatment models and their respective time-varying covariates with measurement error is needed. This study examines such mismeasurement systematically through Monte Carlo simulations when correction methods are and are not used. Here, the outcome of interest focused on the potential bias in the estimation of the average treatment effect for different treatment histories. Variation in simulation conditions reflect parameter issues in measurement error as it relates to reliability, treatment group size, type of latent covariate proxy, degree of effect, and other contributing factors to propensity score models and marginal structural models. Overall, the latent covariate proxy approaches generally resulted in increased bias and less prediction accuracy as measurement error in the latent covariate increased. Unequal treatment and control group sizes was a large contributing factor among manipulated factors and resulted in increased bias and prediction accuracy as compared to conditions with equal control and treatment group sizes. Overall, the inclusive factor score that accounts for treatment at all time points performed more optimally than the comparison latent covariate proxy methods. Limitations and implications for researchers are discussed.Educational Psycholog
Method of remotely characterizing thermal properties of a sample
A sample in a wind tunnel is radiated from a thermal energy source outside of the wind tunnel. A thermal imager system, also located outside of the wind tunnel, reads surface radiations from the sample as a function of time. The produced thermal images are characteristic of the heat transferred from the sample to the flow across the sample. In turn, the measured rates of heat loss of the sample are characteristic of the flow and the sample
The Conserved G-Protein Coupled Receptor FSHR-1 Regulates Protective Host Responses to Infection and Oxidative Stress
The innate immune system’s ability to sense an infection is critical so that it can rapidly respond if pathogenic microorganisms threaten the host, but otherwise maintain a quiescent baseline state to avoid causing damage to the host or to commensal microorganisms. One important mechanism for discriminating between pathogenic and non-pathogenic bacteria is the recognition of cellular damage caused by a pathogen during the course of infection. InCaenorhabditis elegans, the conserved G-protein coupled receptor FSHR-1 is an important constituent of the innate immune response. FSHR-1 activates the expression of antimicrobial infection response genes in infected worms and delays accumulation of the ingested pathogenPseudomonas aeruginosa. FSHR-1 is central not only to the worm’s survival of infection by multiple pathogens, but also to the worm’s survival of xenobiotic cadmium and oxidative stresses. Infected worms produce reactive oxygen species to fight off the pathogens; FSHR-1 is required at the site of infection for the expression of detoxifying genes that protect the host from collateral damage caused by this defense response. Finally, the FSHR-1 pathway is important for the ability of worms to discriminate pathogenic from benign bacteria and subsequently initiate an aversive learning program that promotes selective pathogen avoidance
Supersonic boundary-layer transition on the LaRC F-106 and the DFRF F-15 aircraft. Part 1: Transition measurements and stability analysis
For the case of the F-15 flight tests, boundary layer transition was observed up to Mach numbers of 1.2. For very limited and specific flight conditions, laminar flow existed back to about 20 percent chord on the surface clean up glove. Hot film instrumentation was effective for locating the region of transition. For the F-106 flight tests, transition on the wing or vertical tail generally occurred very near the attachment line. Transition was believed to be caused by either attachment line contamination or strong cross flow development due to the high sweep angles of the test articles. The compressibility analysis showed that cross flow N-factors were in the range of 5 to 12 at transition
Hydroacoustic Survey and Point Sampling of Macrophytes In Diamond Lake 2009
MaxDepth Aquatics, Inc. was contracted to conduct a hydroacoustic survey of macrophyte distribution in Diamond Lake in 2009. The survey essentially repeated surveys conducted in 2002 and 2007, allowing for a detailed assessment of conditions in 2009 and comparisons among previous years. In addition, Portland State University was contracted to conduct a depth stratified random point sample survey of macrophyte species presence and absence. The point sample survey was similar to surveys conducted in 2005 and 2007. The results of the 2009 hydroacoustic survey showed that macrophytes were widely distributed throughout the lake at depths less than 8 meters, although some shorter aggregations of macrophytes were found at depths down to 14 meters. Average canopy height corresponded closely to macrophyte density in 2009. The recent survey showed that macrophytes had extended deeper throughout the lake compared to 2002 and 2007 and that canopy height had increased substantially in some locations. The 2009 distribution showed that recolonization of the near shore areas was proceeding, albeit at a relatively slow pace since the lake drawdown completed in 2006. The maximum density of macrophytes in 2009 was found between 4 to 6 meters. Five macrophyte species, one macroalgal species, and filamentous algae were present in the 2009 random point survey. The occurrence rates of the macrophytes Elodea canadensis, Ceratophyllum demersum, and Potamogeton praelongus in 2009 were similar to 2005 and 2007 while Potamogeton pusillus occurrence increased and Myriophyllum verticillatum decreased. Macrophytes were present in a few samples greater than 9 meters; however, biomass, as measured by the fullness of a sampling rake, was highest between 2 and 6 meters. The comparison of the grab sampling conducted in August with the hydroacoustic survey in early September showed poor correspondence in macrophyte density obtained by the two methods. This is likely due to differences in spatial scales of collected samples (10 m2 grid for hydroacoustics compared to \u3c 1 m2 grab samples), comparison of a continuous analytic tool (hydroacoustic) versus an ordinal ranking of density (rake), and possibly some changes in the macrophytes community between the two sampling dates
Probe-pulse optimization for nonresonant suppression in hybrid fs/ps coherent anti-Stokes Raman scattering at high temperature
Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) offers accurate thermometry at kHz rates for combustion diagnostics. In high-temperature flames, selection of probe-pulse characteristics is key to simultaneously optimizing signal-to-nonresonant-background ratio, signal strength, and spectral resolution. We demonstrate a simple method for enhancing signal-to-nonresonant-background ratio by using a narrowband Lorentzian filter to generate a time-asymmetric probe pulse with full-width-half-maximum (FWHM) pulse width of only 240 fs. This allows detection within just 310 fs after the Raman excitation for eliminating nonresonant background while retaining 45% of the resonant signal at 2000 K. The narrow linewidth is comparable to that of a time-symmetric sinc2 probe pulse with a pulse width of ~2.4 ps generated with a conventional 4-f pulse shaper. This allows nonresonant-background-free, frequency-domain vibrational spectroscopy at high temperature, as verified using comparisons to a time-dependent theoretical fs/ps CARS model
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