2,518 research outputs found

    Graying of the Professoriate Reconsidered: The Impact of Demographics on Criminal Justice Education

    Get PDF
    The demographic composition, especially the age structure of criminal justice faculty, is of interest to students in criminal justice education for a number of reasons. First, an overall assessment provides some gauge of the relative age of the faculty in the field. Second, observations of changes in the composition of the age structure over time provide insight into the aging process and attendant developmental process of the field itself. Third, age composition has a major impact on the job market for criminal justice faculty. This of course, in turn, partially determines career possibilities for neophytes in the field. It also serves as a major factor in setting the limits of both vertical and horizontal faculty career mobility. Fourth, age composition has a direct bearing on potential for improving the quality of criminal justice education

    Ion Thruster Development at NASA Lewis Research Center

    Get PDF
    Recent ion propulsion technology efforts at NASA's Lewis Research Center including development of kW-class xenon ion thrusters, high power xenon and krypton ion thrusters, and power processors are reviewed. Thruster physical characteristics, performance data, life projections, and power processor component technology are summarized. The ion propulsion technology program is structured to address a broad set of mission applications from satellite stationkeeping and repositioning to primary propulsion using solar or nuclear power systems

    Ocean model-based covariates improve a marine fish stock assessment when observations are limited

    Get PDF
    The productivity of many fish populations is influenced by the environment, but developing environment-linked stock assessments remain challenging and current management of most commercial species assumes that stock productivity is time-invariant. In the Northeast United States, previous studies suggest that the recruitment of Southern New England-Mid Atlantic yellowtail flounder is closely related to the strength of the Cold Pool, a seasonally formed cold water mass on the continental shelf. Here, we developed three new indices that enhance the characterization of Cold Pool interannual variations using bottom temperature from a regional hindcast ocean model and a global ocean data assimilated hindcast. We associated these new indices to yellowtail flounder recruitment in a state–space, age-structured stock assessment framework using the Woods Hole Assessment Model. We demonstrate that incorporating Cold Pool effects on yellowtail flounder recruitment reduces the retrospective patterns and may improve the predictive skill of recruitment and, to a lesser extent, spawning stock biomass. We also show that the performance of the assessment models that incorporated ocean model-based indices is improved compared to the model using only the observation-based index. Instead of relying on limited subsurface observations, using validated ocean model products as environmental covariates in stock assessments may both improve predictions and facilitate operationalization.publishedVersio

    Algorithm Selection Framework for Cyber Attack Detection

    Full text link
    The number of cyber threats against both wired and wireless computer systems and other components of the Internet of Things continues to increase annually. In this work, an algorithm selection framework is employed on the NSL-KDD data set and a novel paradigm of machine learning taxonomy is presented. The framework uses a combination of user input and meta-features to select the best algorithm to detect cyber attacks on a network. Performance is compared between a rule-of-thumb strategy and a meta-learning strategy. The framework removes the conjecture of the common trial-and-error algorithm selection method. The framework recommends five algorithms from the taxonomy. Both strategies recommend a high-performing algorithm, though not the best performing. The work demonstrates the close connectedness between algorithm selection and the taxonomy for which it is premised.Comment: 6 pages, 7 figures, 1 table, accepted to WiseML '2

    Effect of preexcisional heparin anticoagulation on excised canine vein and artery prostanoid production

    Full text link
    The effect of heparin, administered prior to vessel dissection and excision, on the luminal release of prostanoids from an excised vessel was assessed. Eight adult mongrel dogs underwent removal of the jugular vein and carotid artery on one side, followed by intravenous administration of heparin sodium (150 IU/kg) and subsequent removal of these same vessels from the contralateral neck. The excised vessels were perfused in an ex vivo system with Hanks' balanced salt solution for five consecutive 15-min periods. Prostacyclin release (measured as 6-keto-PGF1[alpha]) and thromboxane A2 (measured as thromboxane B2) release into the perfusate were quantitated by radioimmunoassay. Vessel segments were studied with and without first period thrombin stimulation (2 U/ml) and with arachidonic acid (4 [mu]g/ml) stimulation during the last perfusion period. Vein segments following heparin administration exhibited greater prostacyclin production than veins not exposed to heparin. This effect did not occur in arteries. Heparin did not influence thromboxane A2 release. Luminal endothelial cell coverage was not affected by the presence or absence of heparin. Thus heparin anticoagulation prior to dissection and excision of a vein, may enhance early preservation of its endothelial cell function as evident by increased luminal release of prostacyclin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27928/1/0000352.pd

    Seasonal prediction of bottom temperature on the Northeast U.S. Continental Shelf

    Get PDF
    © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chen, Z., Kwon, Y.-O., Chen, K., Fratantoni, P., Gawarkiewicz, G., Joyce, T. M., Miller, T. J., Nye, J. A., Saba, V. S., & Stock, B. C. Seasonal prediction of bottom temperature on the Northeast U.S. Continental Shelf. Journal of Geophysical Research: Oceans, 126(5), (2021): e2021JC017187, https://doi.org/10.1029/2021JC017187.The Northeast U.S. shelf (NES) is an oceanographically dynamic marine ecosystem and supports some of the most valuable demersal fisheries in the world. A reliable prediction of NES environmental variables, particularly ocean bottom temperature, could lead to a significant improvement in demersal fisheries management. However, the current generation of climate model-based seasonal-to-interannual predictions exhibits limited prediction skill in this continental shelf environment. Here, we have developed a hierarchy of statistical seasonal predictions for NES bottom temperatures using an eddy-resolving ocean reanalysis data set. A simple, damped local persistence prediction model produces significant skill for lead times up to ∼5 months in the Mid-Atlantic Bight and up to ∼10 months in the Gulf of Maine, although the prediction skill varies notably by season. Considering temperature from a nearby or upstream (i.e., more poleward) region as an additional predictor generally improves prediction skill, presumably as a result of advective processes. Large-scale atmospheric and oceanic indices, such as Gulf Stream path indices (GSIs) and the North Atlantic Oscillation Index, are also tested as predictors for NES bottom temperatures. Only the GSI constructed from temperature observed at 200 m depth significantly improves the prediction skill relative to local persistence. However, the prediction skill from this GSI is not larger than that gained using models incorporating nearby or upstream shelf/slope temperatures. Based on these results, a simplified statistical model has been developed, which can be tailored to fisheries management for the NES.This work was supported by NOAA's Climate Program Office's Modeling, Analysis, Predictions, and Projections (MAPP) Program (NA17OAR4310111, NA19OAR4320074), and Climate Program Office's Climate Variability and Predictability (CVP) Program (NA20OAR4310482). We acknowledge our participation in MAPP's Marine Prediction Task Force

    What is a sentinel node? Re-evaluating the 10% rule for sentinel lymph node biopsy in melanoma

    Full text link
    Introduction Many surgeons use the “10% rule” to define whether a lymph node is a sentinel node (SLN) when staging malignant melanoma. However, this increases the number of SLN removed and the time and cost of the procedure. We examined the impact of raising this threshold on the accuracy of the procedure. Methods We reviewed the records of 561 patients with melanoma (624 basins) who underwent SLN with technetium Tc99 labeled sulfur colloid using a definition of a SLN as 10% of that of the node with the highest counts per minute (CPM). Results Of the 624 basins, 154 (25%) were positive for metastases. An average of 1.9 nodes per basin were removed (range 1–6). Metastases were found in the hottest node in 137 cases (89% of positive basins, 97% of basins overall). Increasing the threshold above 10% decreased the number of nodes excised and the costs involved, but incrementally raised the number of false negative cases above baseline (a 4% increase for a “20% rule,” 5% for a “30% rule,” 6% for a “40% rule,” and 7% for a “50% rule”). Taking only the hottest node would raise the false negative rate by 11%. Conclusions Although using thresholds higher than 10% for the definition of a SLN will minimize the extent of surgery and decrease the costs associated with the procedure, it will compromise the accuracy of the procedure and is not recommended. J. Surg. Oncol. 2007;95:623–628. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56055/1/20729_ftp.pd

    Do Global Diversity Patterns of Vertebrates Reflect Those of Monocots?

    Get PDF
    Few studies of global diversity gradients in plants exist, largely because the data are not available for all species involved. Instead, most global studies have focussed on vertebrates, as these taxa have historically been associated with the most complete data. Here, we address this shortfall by first investigating global diversity gradients in monocots, a morphologically and functionally diverse clade representing a quarter of flowering plant diversity, and then assessing congruence between monocot and vertebrate diversity patterns. To do this, we create a new dataset that merges biome-level associations for all monocot genera with country-level associations for almost all ∼70,000 species. We then assess the evidence for direct versus indirect effects of this plant diversity on vertebrate diversity using a combination of linear regression and structural equation modelling (SEM). Finally, we also calculate overlap of diversity hotspots for monocots and each vertebrate taxon. Monocots follow a latitudinal gradient although with pockets of extra-tropical diversity, mirroring patterns in vertebrates. Monocot diversity is positively associated with vertebrate diversity, but the strength of correlation varies depending on the clades being compared. Monocot diversity explains marginal amounts of variance (<10%) after environmental factors have been accounted for. However, correlations remain among model residuals, and SEMs apparently reveal some direct effects of monocot richness. Our results suggest that collinear responses to environmental gradients are behind much of the congruence observed, but that there is some evidence for direct effects of producer diversity on consumer diversity. Much remains to be done before broad-scale diversity gradients among taxa are fully explained. Our dataset of monocot distributions will aid in this endeavour
    corecore