1,466 research outputs found
Field testing a novel high residence positioning system for monitoring the fineâscale movements of aquatic organisms
1. Acoustic telemetry is an important tool for studying the behaviour of aquatic organisms in the wild.
2. VEMCO high residence (HR) tags and receivers are a recent introduction in the field of acoustic telemetry and can be paired with existing algorithms (e.g. VEMCO positioning system [VPS]) to obtain highâresolution twoâdimensional positioning data.
3. Here, we present results of the first documented field test of a VPS composed of HR receivers (hereafter, HRâVPS). We performed a series of stationary and moving trials with HR tags (mean HR transmission period = 1.5 s) to evaluate the precision, accuracy and temporal capabilities of this positioning technology. In addition, we present a sample of data obtained for five European perch Perca fluviatilis implanted with HR tags (mean HR transmission period = 4 s) to illustrate how this technology can estimate the fineâscale behaviour of aquatic animals.
4. Accuracy and precision estimates (median [5thâ95th percentile]) of HRâVPS positions for all stationary trials were 5.6 m (4.2â10.8 m) and 0.1 m (0.02â0.07 m), respectively, and depended on the location of tags within the receiver array. In moving tests, tracks generated by HRâVPS closely mimicked those produced by a handheld GPS held over the tag, but these differed in location by an average of â9 m.
5. We found that estimates of animal speed and distance travelled for perch declined when positional data for acoustically tagged perch were thinned to mimic longer transmission periods. These data also revealed a tradeâoff between capturing real nonlinear animal movements and the inclusion of positioning error.
6. Our results suggested that HRâVPS can provide more representative estimates of movement metrics and offer an advancement for studying fineâscale movements of aquatic organisms, but highâprecision survey techniques may be needed to test these systems
Cloning, sequencing, and characterization of the hexahydro-1,3,5-trinitro-1,3,5-triazine degradation gene cluster from Rhodococcus rhodochrous
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a high explosive which presents an environmental hazard as a major land and groundwater contaminant. Rhodococcus rhodochrous strain 11Y was isolated from explosive contaminated land and is capable of degrading RDX when provided as the sole source of nitrogen for growth. Products of RDX degradation in resting-cell incubations were analyzed and found to include nitrite, formaldehyde, and formate. No ammonium was excreted into the medium, and no dead-end metabolites were observed. The gene responsible for the degradation of RDX in strain 11Y is a constitutively expressed cytochrome P450-like gene, xpLA, which is found in a gene cluster with an adrenodoxin reductase homologue, xplB. The cytochrome P450 also has a flavodoxin domain at the N terminus. This study is the first to present a gene which has been identified as being responsible for RDX biodegradation. The mechanism of action of XplA on RDX is thought to involve initial denitration followed by spontaneous ring cleavage and mineralization
Cystic Fibrosis Airway Epithelia Fail to Kill Bacteria Because of Abnormal Airway Surface Fluid
AbstractDespite an increased understanding of the cellular and molecular biology of the CFTR Clâ channel, it is not known how defective Clâ transport across airway epithelia causes chronic bacterial infections in cystic fibrosis (CF) airways. Here, we show that common CF pathogens were killed when added to the apical surface of normal airway epithelia. In contrast, these bacteria multiplied on CF epithelia. We found that bactericidal activity was present in airway surface fluid of both normal and CF epithelia. However, because bacterial killing required a low NaCl concentration and because CF surface fluid has a high NaCl concentration, CF epithelia failed to kill bacteria. This defect was corrected by reducing the NaCl concentration on CF epithelia. These data explain how the loss of CFTR Clâ channels may lead to lung disease and suggest new approaches to therapy
Dramatic Plays as a Tool to Educate Young African-American Females about HIV/AIDS
Rates of HIV/AIDS transmission have increased substantially, particularly among young African American women. According to the Centers for Disease Control and Prevention (CDC), HIV/AIDS is the number one killer for African American women aged 25 to 34. Given that many of these young women are contracting the disease in their late teens and early twenties, there is a need to develop interventions that directly address the needs of this group. The current study sought to assess the effectiveness of theater in increasing knowledge of HIV/AIDS and the likelihood of healthier sexual behavior and choices among 219 young African American women 18 to 39 years of age. Paired sample t-tests revealed that there were significant mean differences in knowledge and intended safe sex behavior after viewing the play. Young women who viewed the play reported increased knowledge of HIV and reported a higher likelihood of engaging in safer sex. Given the high rates of HIV/AIDS among young African American women, more innovative educational and prevention techniques are needed
Evaluation of Content and Accessibility of Orthopaedic Trauma Fellowship Websites
Background: Residents frequently use the internet to find material on fellowship programs. The Orthopaedic Trauma Association (OTA) website serves as a central hub for information on an orthopaedic trauma fellowship (OTF). This study aims to evaluate the accessibility, content, and perceived importance of OTF websites.
Methods: We reviewed the 49 OTFs accredited by the OTA fellowship database as of January 2014. We searched for corresponding OTF websites by using the provided OTA hyperlinks and conducting a separate Google search of program location and institution. Links to websites of general orthopaedic programs were not counted. Content of OTF websites was analyzed by noting the presence or absence of specific items in fellow education (11 items) and recruitment (5 items).
Results: Of 49 OTFs, a total of 39 (80%) websites specific to the fellowship were identified by searching the OTA database and Google browser. Seven (14%) programs listed on the OTA database provided links directly to fellowship programs. Most programs (28; 57%) did not provide links to specific OTFs or provided non-functional links on the OTA website. Of the 39 accessible OTF websites, a total of 24 (61%) had complete information regarding recruitment and 14 (36%) provided complete details on education.
Conclusions: Most accredited OTFs do not adequately use the internet to provide easily accessible and complete information. Further details (especially regarding the role, education, and schedule) would help prospective candidates in thoroughly evaluating programs. The discrepancy in content and accessibility can hinder prospective fellows from appropriately investigating fellowship programs
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Cost Shared Wildfire Risk Mitigation in Log Hill Mesa, Colorado: Survey Evidence on Participation and Willingness to Pay
Wildlandâurban interface (WUI) homeowners who do not mitigate the wildfire risk on their properties impose a negative externality on society. To reduce the social costs of wildfire and incentivise homeowners to take action, cost sharing programs seek to reduce the barriers that impede wildfire risk mitigation. Using survey data from a WUI community in western Colorado and a two-stage decision framework, we examine residentsâ willingness to participate in a cost sharing program for removing vegetation on their properties and the amount they are willing to contribute to the cost of that removal. Wefind that different factors motivate decisions about participation and about how much to pay. Willingness to participate correlates with both financial and non-monetary considerations, including informational barriers and wildfire risk perceptions, but not with concerns about effectiveness or visual impacts. Residents of properties with higher wildfire risk levels are less likely to participate in the cost sharing than those with lower levels of wildfire risk. We find widespread, positive willingness to pay for vegetation removal, with the amount associated negatively with property size and positively with respondent income. These results can inform the development of cost sharing programs to encourage wildfire risk mitigation on private property
Factorized Graph Representations for Semi-Supervised Learning from Sparse Data
Node classification is an important problem in graph data management. It is
commonly solved by various label propagation methods that work iteratively
starting from a few labeled seed nodes. For graphs with arbitrary
compatibilities between classes, these methods crucially depend on knowing the
compatibility matrix that must be provided by either domain experts or
heuristics. Can we instead directly estimate the correct compatibilities from a
sparsely labeled graph in a principled and scalable way? We answer this
question affirmatively and suggest a method called distant compatibility
estimation that works even on extremely sparsely labeled graphs (e.g., 1 in
10,000 nodes is labeled) in a fraction of the time it later takes to label the
remaining nodes. Our approach first creates multiple factorized graph
representations (with size independent of the graph) and then performs
estimation on these smaller graph sketches. We define algebraic amplification
as the more general idea of leveraging algebraic properties of an algorithm's
update equations to amplify sparse signals. We show that our estimator is by
orders of magnitude faster than an alternative approach and that the end-to-end
classification accuracy is comparable to using gold standard compatibilities.
This makes it a cheap preprocessing step for any existing label propagation
method and removes the current dependence on heuristics.Comment: SIGMOD 2020 (Extended version
Territorial Tactics: The Socio-spatial Significance of Private Policing Strategies in Cape Town
This paper analyses the policing strategies of private security companies operating in urban space. An existing literature has considered the variety of ways that territory becomes of fundamental importance in the work of public police forces. However, this paper examines territory in the context of private security companies. Drawing on empirical research in Cape Town, it examines how demarcated territories become key subjects in private policing. Private security companies are responsible for a relatively small section of the city, while in contrast the public police ultimately have to see city space as a whole. Hence, private policing strategy becomes one of displacement, especially of so-called undesirables yielding a patchworked public space associated with private enclaves of consumption. The conclusions signal the historical resonances and comparative implications of these political-legal-security dynamics. © 2013 Urban Studies Journal Limited
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