1,766 research outputs found

    Contextual anomaly detection in crowded surveillance scenes

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    AbstractThis work addresses the problem of detecting human behavioural anomalies in crowded surveillance environments. We focus in particular on the problem of detecting subtle anomalies in a behaviourally heterogeneous surveillance scene. To reach this goal we implement a novel unsupervised context-aware process. We propose and evaluate a method of utilising social context and scene context to improve behaviour analysis. We find that in a crowded scene the application of Mutual Information based social context permits the ability to prevent self-justifying groups and propagate anomalies in a social network, granting a greater anomaly detection capability. Scene context uniformly improves the detection of anomalies in both datasets. The strength of our contextual features is demonstrated by the detection of subtly abnormal behaviours, which otherwise remain indistinguishable from normal behaviour

    Is This Bacterial Leaf Streak?

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    Bacterial leaf streak was confirmed for the first time in Iowa and other states in 2016. There is not a lot known about the disease but researchers at Colorado State University, Iowa State University, Kansas State University and University of Nebraska are collaborating to understand the disease and its impact on corn with partial funding through the Farm Bill

    Gray-matter volume, midbrain dopamine D2/D3 receptors and drug craving in methamphetamine users.

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    Dysfunction of the mesocorticolimbic system has a critical role in clinical features of addiction. Despite evidence suggesting that midbrain dopamine receptors influence amphetamine-induced dopamine release and that dopamine is involved in methamphetamine-induced neurotoxicity, associations between dopamine receptors and gray-matter volume have been unexplored in methamphetamine users. Here we used magnetic resonance imaging and [(18)F]fallypride positron emission tomography, respectively, to measure gray-matter volume (in 58 methamphetamine users) and dopamine D2/D3 receptor availability (binding potential relative to nondisplaceable uptake of the radiotracer, BPnd) (in 31 methamphetamine users and 37 control participants). Relationships between these measures and self-reported drug craving were examined. Although no difference in midbrain D2/D3 BPnd was detected between methamphetamine and control groups, midbrain D2/D3 BPnd was positively correlated with gray-matter volume in the striatum, prefrontal cortex, insula, hippocampus and temporal cortex in methamphetamine users, but not in control participants (group-by-midbrain D2/D3 BPnd interaction, P<0.05 corrected for multiple comparisons). Craving for methamphetamine was negatively associated with gray-matter volume in the insula, prefrontal cortex, amygdala, temporal cortex, occipital cortex, cerebellum and thalamus (P<0.05 corrected for multiple comparisons). A relationship between midbrain D2/D3 BPnd and methamphetamine craving was not detected. Lower midbrain D2/D3 BPnd may increase vulnerability to deficits in gray-matter volume in mesocorticolimbic circuitry in methamphetamine users, possibly reflecting greater dopamine-induced toxicity. Identifying factors that influence prefrontal and limbic volume, such as midbrain BPnd, may be important for understanding the basis of drug craving, a key factor in the maintenance of substance-use disorders

    Optimality program in segment and string graphs

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    Planar graphs are known to allow subexponential algorithms running in time 2O(n)2^{O(\sqrt n)} or 2O(nlogn)2^{O(\sqrt n \log n)} for most of the paradigmatic problems, while the brute-force time 2Θ(n)2^{\Theta(n)} is very likely to be asymptotically best on general graphs. Intrigued by an algorithm packing curves in 2O(n2/3logn)2^{O(n^{2/3}\log n)} by Fox and Pach [SODA'11], we investigate which problems have subexponential algorithms on the intersection graphs of curves (string graphs) or segments (segment intersection graphs) and which problems have no such algorithms under the ETH (Exponential Time Hypothesis). Among our results, we show that, quite surprisingly, 3-Coloring can also be solved in time 2O(n2/3logO(1)n)2^{O(n^{2/3}\log^{O(1)}n)} on string graphs while an algorithm running in time 2o(n)2^{o(n)} for 4-Coloring even on axis-parallel segments (of unbounded length) would disprove the ETH. For 4-Coloring of unit segments, we show a weaker ETH lower bound of 2o(n2/3)2^{o(n^{2/3})} which exploits the celebrated Erd\H{o}s-Szekeres theorem. The subexponential running time also carries over to Min Feedback Vertex Set but not to Min Dominating Set and Min Independent Dominating Set.Comment: 19 pages, 15 figure

    Free-Flight Terrestrial Rocket Lander Demonstration for NASA's Autonomous Landing and Hazard Avoidance Technology (ALHAT) System

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    The Autonomous Landing Hazard Avoidance Technology (ALHAT) Project is chartered to develop and mature to a Technology Readiness Level (TRL) of six an autonomous system combining guidance, navigation and control with terrain sensing and recognition functions for crewed, cargo, and robotic planetary landing vehicles. The ALHAT System must be capable of identifying and avoiding surface hazards to enable a safe and accurate landing to within tens of meters of designated and certified landing sites anywhere on a planetary surface under any lighting conditions. Since its inception in 2006, the ALHAT Project has executed four field test campaigns to characterize and mature sensors and algorithms that support real-time hazard detection and global/local precision navigation for planetary landings. The driving objective for Government Fiscal Year 2012 (GFY2012) is to successfully demonstrate autonomous, real-time, closed loop operation of the ALHAT system in a realistic free flight scenario on Earth using the Morpheus lander developed at the Johnson Space Center (JSC). This goal represents an aggressive target consistent with a lean engineering culture of rapid prototyping and development. This culture is characterized by prioritizing early implementation to gain practical lessons learned and then building on this knowledge with subsequent prototyping design cycles of increasing complexity culminating in the implementation of the baseline design. This paper provides an overview of the ALHAT/Morpheus flight demonstration activities in GFY2012, including accomplishments, current status, results, and lessons learned. The ALHAT/Morpheus effort is also described in the context of a technology path in support of future crewed and robotic planetary exploration missions based upon the core sensing functions of the ALHAT system: Terrain Relative Navigation (TRN), Hazard Detection and Avoidance (HDA), and Hazard Relative Navigation (HRN)

    Proton Capture on ^{17}O and its astrophysical implications

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    The reaction 17^{17}O(p,γ)18(p,\gamma)^{18}F influences hydrogen-burning nucleosynthesis in several stellar sites, such as red giants, asymptotic giant branch (AGB) stars, massive stars and classical novae. In the relevant temperature range for these environments (T9=0.010.4),themaincontributionstotherateofthisreactionarethedirectcaptureprocess,twolowlyingnarrowresonances(T_{9}=0.01-0.4), the main contributions to the rate of this reaction are the direct capture process, two low lying narrow resonances (E_{r}=65.1and183keV)andthelowenergytailsoftwobroadresonances( and 183 keV) and the low-energy tails of two broad resonances (E_{r}=557and677keV).Previousmeasurementsandcalculationsgivecontradictoryresultsforthedirectcapturecontributionwhichinturnincreasestheuncertaintyofthereactionrate.Inaddition,veryfewpublishedcrosssectiondataexistforthehighenergyregionthatmightaffecttheinterpretationofthedirectcaptureandthecontributionsofthebroadresonancesinthelowerenergyrange.Thisworkaimstoaddresstheseissues.Thereactioncrosssectionwasmeasuredinawideprotonenergyrange( and 677 keV). Previous measurements and calculations give contradictory results for the direct capture contribution which in turn increases the uncertainty of the reaction rate. In addition, very few published cross section data exist for the high energy region that might affect the interpretation of the direct capture and the contributions of the broad resonances in the lower energy range. This work aims to address these issues. The reaction cross section was measured in a wide proton energy range (E_{c.m.}=3451700keV)andatseveralangles( - 1700 keV) and at several angles (\theta_{lab}=0^{\circ},45^{\circ},90^{\circ},135^{\circ}).Theobservedprimary). The observed primary \gammatransitionswereusedasinputinan-transitions were used as input in an Rmatrixcodeinordertoobtainthecontributionofthedirectcaptureandthetwobroadresonancestothelowenergyregion.TheextrapolatedSfactorfromthepresentdataisingoodagreementwiththeexistingliteraturedatainthelowenergyregion.AnewreactionratewascalculatedfromthecombinedresultsofthisworkandliteratureSfactordeterminations.Resonancestrengthsandbranchingsarereportedforseveral-matrix code in order to obtain the contribution of the direct capture and the two broad resonances to the low-energy region. The extrapolated S-factor from the present data is in good agreement with the existing literature data in the low-energy region. A new reaction rate was calculated from the combined results of this work and literature S-factor determinations. Resonance strengths and branchings are reported for several ^{18}Fstates.WewereabletoextrapolatetheastrophysicalSfactorofthereactionF states. We were able to extrapolate the astrophysical S-factor of the reaction ^{17}OO(p,\gamma)^{18}$F at low energies from cross section data taken at higher energies. No significant changes in the nucleosynthesis are expected from the newly calculated reaction rate.Comment: Accepted in Physical Review

    Submaximal Oviposition Rates in a Mymarid Parasitoid: Choosiness Should Not Be Ignored

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    Cronin and Strong (1993a, b) examined the oviposition behavior of Anagarus delicatus Dozier (Hymenoptera: Mymaridae), an egg parasitoid of the leafhopper Prokelisia marginate Van Duzee (Homoptera: Delphacidae). They reported oviposition rates that were lower than predicted if the rate of egg-laying was maximized. Cronin and Strong (1993a) considered, and subsequently rejected, several “rules of thumb” (Stephens and Krebs 1986) as explanations for the observed patterns of patch departure. They observed that hosts on leaves experience density-independent mortality due to leaf senescence. Based on that, they advanced the hypothesis that submaximal oviposition rates in A. delicatus are best explained as risk-spreading by the parasitoid. (That is, by laying a small number of eggs on many leaves, the parasitoid increases the probability that some of her offspring will survive; Cronin and Strong 1993a.) An alternative hypothesis (Rosenheim and Mangel 1994) suggests that by distributing the eggs among several leaves, A. delicatus avoids self-superparasitism. Here, we take a somewhat different approach than those provided above to explain an additional observation of Cronin and Strong (1993a): female wasps rejected most of the hosts that they had probed. In so doing, we argue that rate maximization was an inappropriate prediction for A. delicatus, and in light of the life history parameters of this species, egg limitation is more suitable. Furthermore, egg limitation, when combined with one of the proposed explanations for the distribution of eggs, can explain the high rejection level of potential hosts

    Submaximal Oviposition Rates in a Mymarid Parasitoid: Choosiness Should Not Be Ignored

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    Cronin and Strong (1993a, b) examined the oviposition behavior of Anagarus delicatus Dozier (Hymenoptera: Mymaridae), an egg parasitoid of the leafhopper Prokelisia marginate Van Duzee (Homoptera: Delphacidae). They reported oviposition rates that were lower than predicted if the rate of egg-laying was maximized. Cronin and Strong (1993a) considered, and subsequently rejected, several “rules of thumb” (Stephens and Krebs 1986) as explanations for the observed patterns of patch departure. They observed that hosts on leaves experience density-independent mortality due to leaf senescence. Based on that, they advanced the hypothesis that submaximal oviposition rates in A. delicatus are best explained as risk-spreading by the parasitoid. (That is, by laying a small number of eggs on many leaves, the parasitoid increases the probability that some of her offspring will survive; Cronin and Strong 1993a.) An alternative hypothesis (Rosenheim and Mangel 1994) suggests that by distributing the eggs among several leaves, A. delicatus avoids self-superparasitism. Here, we take a somewhat different approach than those provided above to explain an additional observation of Cronin and Strong (1993a): female wasps rejected most of the hosts that they had probed. In so doing, we argue that rate maximization was an inappropriate prediction for A. delicatus, and in light of the life history parameters of this species, egg limitation is more suitable. Furthermore, egg limitation, when combined with one of the proposed explanations for the distribution of eggs, can explain the high rejection level of potential hosts

    University of Nebraska-Lincoln School of Natural Resources Review: Final Report, December 2003

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    In July 2003, the School of Natural Resource Sciences was merged with the Conservation and Survey Division and the Water Center Nebraska State Survey. This merger produced the School of Natural Resources (hereafter referred to as the School ) in its current form. The University of Nebraska-Lincoln requested a ten-year review of the School\u27s programs and activities. The review was administered by the Cooperative State Research, Education and Extension Service (CSREES) in cooperation with the University of Nebraska-Lincoln\u27s Institute of Agriculture and Natural Resources, the College of Agriculture, and the School. The review document is divided into nine sections. The first section provides the basic background to the Report. Sections two through seven describe opportunities and challenges faced by the School organized around seven elements of a framework adopted by the Review Team. Section eight presents a summary of recommendations found within the report and the final section lists references cited in this report. Key Recommendations 1. Conduct a two or three day retreat to develop the intellectual core of the School. 2. Based upon the outcome of the retreat, develop a strategic hiring plan for all new faculty. 3. Use a professional facilitator to guide the School through sessions on maintaining the identity of existing centers, groups, and teams while building a common shared culture within the School. 4. Establish a leadership team to revisit definitions of scholarship based on the diverse, complex faculty now in the School. 5. Conduct a complete curriculum review and revision (graduate and undergraduate) around core issues defined in the retreat. 6. Establish a leadership team that promotes communication among all members of the School and insures transparency of decision-making in the School. 7. Devote the necessary resources to locate all faculty, staff, and students associated with the School into the Hardin Hall facility
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