9,722 research outputs found

    Assessing, valuing and protecting our environment- is there a statistical challenge to be answered?

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    This short article describes some of the evolution in environmental regulation, management and monitoring and the information needs, closely aligned to the statistical challenges to deliver the evidence base for change and effect

    The utilization of neural nets in populating an object-oriented database

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    Existing NASA supported scientific data bases are usually developed, managed and populated in a tedious, error prone and self-limiting way in terms of what can be described in a relational Data Base Management System (DBMS). The next generation Earth remote sensing platforms (i.e., Earth Observation System, (EOS), will be capable of generating data at a rate of over 300 Mbs per second from a suite of instruments designed for different applications. What is needed is an innovative approach that creates object-oriented databases that segment, characterize, catalog and are manageable in a domain-specific context and whose contents are available interactively and in near-real-time to the user community. Described here is work in progress that utilizes an artificial neural net approach to characterize satellite imagery of undefined objects into high-level data objects. The characterized data is then dynamically allocated to an object-oriented data base where it can be reviewed and assessed by a user. The definition, development, and evolution of the overall data system model are steps in the creation of an application-driven knowledge-based scientific information system

    Xwnt-5A: a maternal Wnt that affects morphogenetic movements after overexpression in embryos of Xenopus laevis

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    To contribute to an understanding of the roles and mechanisms of action of Wnts in early vertebrate development, we have characterized the normal expression of Xenopus laevis Wnt-5A, and investigated the consequences of misexpression of this putative signalling factor. Xwnt-5A transcripts are expressed throughout development, and are enriched in both the anterior and posterior regions of embryos at late stages of development, where they are found primarily in ectoderm, with lower levels of expression in mesoderm. Overexpression of Xwnt-5A in Xenopus embryos leads to complex malformations distinct from those achieved by ectopic expression of Xwnts −1, −3A, or −8. This phenotype is unlikely to result from Xwnt-5A acting as an inducing agent, as overexpression of Xwnt-5A does not rescue dorsal structures in UV-irradiated embryos, does not induce mesoderm in blastula caps, and Xwnt-5A does not alter the endogenous patterns of expression of goosecoid, Xbra, or Xwnt-8. To pursue whether Xwnt-5A has the capacity to affect morphogenetic movements, we investigated whether overexpression of Xwnt-5A alters the normal elongation of blastula cap explants induced by activin. Intriguingly, Xwnt-5A blocks the elongation of blastula caps in response to activin, without blocking the differentiation of either dorsal or ventral mesoderm within these explants. The data are consistent with Xwnt-5A having the potential activity of modifying the morphogenetic movements of tissues

    Command-level Police Officers’ Perceptions of the “War on Cops” and De-policing

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    Policing has been the subject of intense public scrutiny for the better part of two years after several high-profile police killings of unarmed African Americans across the United States. The scrutiny has been so extreme that some contend there is currently a “war on cops”—whereby citizens are emboldened by protests and negative media coverage of the police, and are lashing out by assaulting police officers more frequently. In response, it is argued that officers are de-policing (i.e. avoiding proactive stops). We surveyed command-level police officers from a southeastern state about their attitudes concerning the war on cops and de-policing. The majority of our sample believed there has been a war on cops over the last two years. Moreover, officers who felt strongly about the existence of a war on cops were more likely to believe that de-policing is common among officers in today’s world of law enforcement

    Constraints on Mars Aphelion Cloud Belt Phase Function and Ice Crystal Geometries

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    This study constrains the lower bound of the scattering phase function of Martian water ice clouds (WICs) through the implementation of a new observation aboard the Mars Science Laboratory (MSL). The Phase Function Sky Survey (PFSS) was a multiple pointing all-sky observation taken with the navigation cameras (Navcam) aboard MSL. The PFSS was executed 35 times during the Aphelion Cloud Belt (ACB) season of Mars Year 34 over a solar longitude range of L_s=61.4{\deg}-156.5{\deg}. Twenty observations occurred in the morning hours between 06:00 and 09:30 LTST, and 15 runs occurred in the evening hours between 14:30 and 18:00 LTST, with an operationally required 2.5 hour gap on either side of local noon due the sun being located near zenith. The resultant WIC phase function was derived over an observed scattering angle range of 18.3{\deg} to 152.61{\deg}, normalized, and compared with 9 modeled phase functions: seven ice crystal habits and two Martian WIC phase functions currently being implemented in models. Through statistical chi-squared probability tests, the five most probable ice crystal geometries observed in the ACB WICs were aggregates, hexagonal solid columns, hollow columns, plates, and bullet rosettes with p-values greater than or equal to 0.60, 0.57,0.56,0.56, and 0.55, respectively. Droxtals and spheres had p-values of 0.35, and 0.2, making them less probable components of Martian WICs, but still statistically possible ones. Having a better understanding of the ice crystal habit and phase function of Martian water ice clouds directly benefits Martian climate models which currently assume spherical and cylindrical particles.Comment: Accepted Manuscript by Planetary and Space Scienc

    Quantitative sensory testing in children with sickle cell disease: additional insights and future possibilities.

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    Quantitative sensory testing (QST) is used in a variety of pain disorders to characterize pain and predict prognosis and response to specific therapies. In this study, we aimed to confirm results in the literature documenting altered QST thresholds in sickle cell disease (SCD) and assess the test-retest reliability of results over time. Fifty-seven SCD and 60 control subjects aged 8-20 years underwent heat and cold detection and pain threshold testing using a Medoc TSAII. Participants were tested at baseline and 3 months; SCD subjects were additionally tested at 6 months. An important facet of our study was the development and use of a novel QST modelling approach, allowing us to model all data together across modalities. We have not demonstrated significant differences in thermal thresholds between subjects with SCD and controls. Thermal thresholds were consistent over a 3- to 6-month period. Subjects on whom hydroxycarbamide (HC) was initiated shortly before or after baseline testing (new HC users) exhibited progressive decreases in thermal sensitivity from baseline to 6 months, suggesting that thermal testing may be sensitive to effective therapy to prevent vasoocclusive pain. These findings inform the use of QST as an endpoint in the evaluation of preventative pain therapies

    Demeanor, Race, and Police Perceptions of Procedural Justice: Evidence from Two Randomized Experiments

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    President Obama’s Task Force on 21st Century Policing recently endorsed procedural justice as a way to restore trust between police and communities. Yet police–citizen interactions vary immensely, and research has yet to give sufficient consideration to the factors that might affect the importance officers place on exercising procedural justice during interactions. Building on research examining “moral worthiness” judgments and racial stereotyping among police officers, we conducted two randomized experiments to test whether suspect race and demeanor affect officers’ perceptions of the threat of violence and importance of exercising procedural justice while interacting with suspicious persons. We find that suspect race fails to exert a statistically significant effect on either outcome. However, demeanor does—such that officers perceive a greater threat of violence and indicate it is less important to exercise procedural justice with disrespectful suspects. These findings have implications for procedural justice training, specifically, and police–community relations more broadly

    Permutation of Two-Term Local Quadrat Variance Analysis: General Concepts for Interpretation of Peaks

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    Many ecological studies use Two-Term Local Quadrat Variance Analysis (TTLQV) and its derivatives for spatial pattern analysis. Currently, rules for determining variance peak significance are arbitrary. Variance peaks found at block size 1 and at \u3e 50 % of the transect length are the only peaks whose use is explicitly prohibited. Although the use of variance peaks found at block sizes \u3e 10 % of the transect length have also been warned against, many researchers interpret them regardless. We show in this paper that variance peaks derived from TTLQV are subject to additional ‘rules of thumb’. Through the use of randomization and permutation analyses on real and simulated data of species abundance in contiguous plots along a single transect, we show that variance peaks found at block sizes 1, 2 and 3 occur frequently by chance and thus likely do not indicate biologically meaningful patterns. The use of multiple replicate transects decreases the probability of Type II error

    Radiographic assessment of the skeletons of Dolly and other clones finds no abnormal osteoarthritis

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    Our recent report detailing the health status of cloned sheep concluded that the animals had aged normally. This is in stark contrast to reports on Dolly (first animal cloned from adult cells) whose diagnoses of osteoarthritis (OA) at 5Âœ years of age led to considerable scientific concern and media debate over the possibility of early-onset age-related diseases in cloned animals. Our study included four 8-year old ewes derived from the cell line that gave rise to Dolly, yet none of our aged sheep showed clinical signs of OA, and they had radiographic evidence of only mild or, in one case, moderate OA. Given that the only formal record of OA in Dolly is a brief mention of a single joint in a conference abstract, this led us to question whether the original concerns about Dolly’s OA were justified. As none of the original clinical or radiographic records were preserved, we undertook radiographic examination of the skeletons of Dolly and her contemporary clones. We report a prevalence and distribution of radiographic-OA similar to that observed in naturally conceived sheep, and our healthy aged cloned sheep. We conclude that the original concerns that cloning had caused early-onset OA in Dolly were unfounded
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