666 research outputs found
THE ECONOMIC THRESHOLD FOR GRASSHOPPER CONTROL ON PUBLIC RANGELANDS
The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) is responsible for controlling grasshopper populations on public rangelands. Under current guidelines, control of grasshoppers on rangeland should occur if grasshopper densities are at least eight per square yard. This article evaluates the concept of an economic threshold relative to the value of forage saved from destruction during a grasshopper outbreak. It is shown that financial justification for treating grasshopper outbreaks depends upon grasshopper density, rangeland productivity, climate factors, livestock cost and return relationships, and the efficacy of treatment options.Resource /Energy Economics and Policy, Land Economics/Use,
Beaufort Gyre Freshwater Experiment : deployment operations and technology 2003
The Beaufort Gyre Freshwater Experiment (BGFE) observational program was designed to
measure the freshwater content of the upper ocean and sea ice in the Beaufort Gyre of the Arctic
Ocean using bottom-tethered moorings, drifting buoys, and hydrographic stations. The mooring
program required the development of a safe and efficient deployment method by which the
subsurface system could be deployed in waters surrounded by sea ice. This report documents the
mooring procedure used to deploy the three BGFE moorings from the CCGS Louis S. St-
Laurent, during the Joint Western Arctic Climate Study ā 2003 (August 6 ā September 7). The
technical details of the instrumentation attached to each mooring and the specific deployment
parameters are described. Specifics pertaining to the deployment of four surface-tethered drifters
in the ice are also documented.Funding was provided by the National Science Foundation under Grant Number OPP-0230184
Unravelling overlaps and torsion-facilitated coupling using two-dimensional laser-induced fluorescence
Two-dimensional laser-induced fluorescence (2D-LIF) spectroscopy is employed to identify contributions to fluorescence excitation spectra that arise from both overlapping bands and coupling between zero-order states (ZOSs). Evidence is found for the role of torsional motion in facilitating the coupling between vibrations that particularly involves the lowest-wavenumber out-of-plane vibrational modes. The experiments are carried out on jet-cooled p-fluorotoluene, where the molecules are initially in the lowest two torsional levels. Here we concentrate on the 390ā420ācmā1 features in the S1āāāS0 excitation spectrum, assigning the features seen in the 2D-LIF spectrum, aided by separate dispersed fluorescence spectra. The 2D-LIF spectra allow the overlapping contributions to be cleanly separated, including some that arise from vibrational-torsional coupling. Various coupling routes open up because of the different symmetries of the lowest two torsional modes; these combine with the vibrational symmetry to provide new symmetry-allowed vibration-torsion (āvibtorā) interactions, and the role of the excited mā=ā1 torsional level is found to be significant
The Beaufort Gyre Observing System 2004 : mooring recovery and deployment operations in pack ice
Situated beneath the Arctic perennial ice pack, the principal components of the
Beaufort Gyre Observing System are three deep-ocean bottom-tethered moorings with
CTD and velocity profilers, upward looking sonars for ice draft measurements, and
bottom pressure recorders. A major goal of this project is to investigate basin-scale
mechanisms regulating freshwater and heat content in the Arctic Ocean and particularly
in the Beaufort Gyre throughout several complete annual cycles. The methods of
recovering and re-deploying the 3800 m long instrumented moorings from the Canadian
Coast Guard Icebreaker Louis S. St. Laurent in August 2004 are described.
In ice-covered regions, deployments must be conducted anchor-first, so heavier
wire rope and hardware must be incorporated into the mooring design. Backup buoyancy
at the bottom of the mooring is advised for backup recovery should intermediate lengths
of the mooring system get tangled under ice floes during recovery. An accurate acoustic
survey to determine the exact location of the mooring, adequate ice conditions, and
skilled ship maneuvering are all essential requirements for a successful mooring
recovery. Windlass (or capstan) procedures could be used for the recovery, but a traction
winch arrangement is recommended.Funding was provided by the National Science Foundation under Grant Number OPP-0230184 and
Woods Hole Oceanographic Insitutionās Ocean and Climate Change Institute
Child relationships in the middle grades
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Biomedical Ph.D. Students Enrolled in Two Elite Universities in the United Kingdom and the United States Report Adopting Multiple Learning Relationships
Objective: The ability to form multiple learning relationships is a key element of the doctoral learning environment in the biomedical sciences. Of these relationships, that between student and supervisor has long been viewed as key. There are, however, limited data to describe the student perspective on what makes this relationship valuable. In the present study, we discuss the findings of semi-structured interviews with biomedical Ph.D. students from the United Kingdom and the United States to: i) determine if the learning relationships identified in an Australian biomedical Ph.D. cohort are also important in a larger international student cohort; and ii) improve our understanding of student perceptions of value in their supervisory relationships. Study Design 32 students from two research intensive universities, one in the United Kingdom (n = 17), and one in the United States (n = 15) were recruited to participate in a semi-structured interview. Verbatim transcripts were transcribed, validated and analysed using a Miles and Huberman method for thematic analysis. Results: Students reported that relationships with other Ph.D. students, post-doctoral scientists and supervisors were all essential to their learning. Effective supervisory relationships were perceived as the primary source of high-level project guidance, intellectual support and confidence. Relationships with fellow students were viewed as essential for the provision of empathetic emotional support. Technical learning was facilitated, almost exclusively, by relationships with postdoctoral staff. Conclusions: These data make two important contributions to the scholarship of doctoral education in the biomedical sciences. Firstly, they provide further evidence for the importance of multiple learning relationships in the biomedical doctorate. Secondly, they clarify the form of a āvaluedā supervisory relationship from a student perspective. We conclude that biomedical doctoral programs should be designed to contain a minimum level of formalised structure to promote the development of multiple learning relationships that are perceived as key to student learning
CitDet: A Benchmark Dataset for Citrus Fruit Detection
In this letter, we present a new dataset to advance the state of the art in
detecting citrus fruit and accurately estimate yield on trees affected by the
Huanglongbing (HLB) disease in orchard environments via imaging. Despite the
fact that significant progress has been made in solving the fruit detection
problem, the lack of publicly available datasets has complicated direct
comparison of results. For instance, citrus detection has long been of interest
in the agricultural research community, yet there is an absence of work,
particularly involving public datasets of citrus affected by HLB. To address
this issue, we enhance state-of-the-art object detection methods for use in
typical orchard settings. Concretely, we provide high-resolution images of
citrus trees located in an area known to be highly affected by HLB, along with
high-quality bounding box annotations of citrus fruit. Fruit on both the trees
and the ground are labeled to allow for identification of fruit location, which
contributes to advancements in yield estimation and potential measure of HLB
impact via fruit drop. The dataset consists of over 32,000 bounding box
annotations for fruit instances contained in 579 high-resolution images. In
summary, our contributions are the following: (i) we introduce a novel dataset
along with baseline performance benchmarks on multiple contemporary object
detection algorithms, (ii) we show the ability to accurately capture fruit
location on tree or on ground, and finally (ii) we present a correlation of our
results with yield estimations.Comment: Submitted to IEEE Robotics and Automation Letters (RA-L
Dynamics of DNA Ejection From Bacteriophage
The ejection of DNA from a bacterial virus (``phage'') into its host cell is
a biologically important example of the translocation of a macromolecular chain
along its length through a membrane. The simplest mechanism for this motion is
diffusion, but in the case of phage ejection a significant driving force
derives from the high degree of stress to which the DNA is subjected in the
viral capsid. The translocation is further sped up by the ratcheting and
entropic forces associated with proteins that bind to the viral DNA in the host
cell cytoplasm. We formulate a generalized diffusion equation that includes
these various pushing and pulling effects and make estimates of the
corresponding speed-ups in the overall translocation process. Stress in the
capsid is the dominant factor throughout early ejection, with the pull due to
binding particles taking over at later stages. Confinement effects are also
investigated, in the case where the phage injects its DNA into a volume
comparable to the capsid size. Our results suggest a series of in vitro
experiments involving the ejection of DNA into vesicles filled with varying
amounts of binding proteins from phage whose state of stress is controlled by
ambient salt conditions or by tuning genome length.Comment: 17 pages, 5 figure
Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
We consider two key parameters that have been proposed to be important for vibrational energy delocalization, closely related to intramolecular vibrational redistribution (IVR), in molecules. These parameters are the symmetry of the molecule, and the presence of torsional (internal rotor) modes of a methyl group. We consider four para-disubstituted benzene molecules and examine their vibrational character. The molecules selected are para-difluorobenzene, para-chlorofluorobenzene, para-fluorotoluene, and para-xylene. This set of molecules allows the above parameters to be assessed in a systematic way. The probe we use is zero-electron-kinetic-energy (ZEKE) spectroscopy, which is employed in a resonant scheme, where the intermediate levels are selected vibrational levels of the S1 excited electronic state, with wavenumbers up to 1300 cm 1. We conclude that symmetry, and the presence of a methyl groups, do indeed have a profound effect on ārestrictedā IVR at low energies. This is underpinned by serendipitous coincidences in the energies of the levels, owing to small shifts in vibrational wavenumbers. Additionally, methyl groups play an important role in opening up new routes for coupling between vibrations of different symmetry, and this is critical in the transition to āstatisticalā IVR at lower energies for molecules that contain them. Further, the presence of two methyl groups in the symmetrically-substituted p-xylene causes more widespread IVR than does the single methyl group in the asymmetrically-substituted p-fluorotoluene
The transcription factor PPARĪ± is overexpressed and is associated with a favourable prognosis in IDH-wildtype primary glioblastoma
Ā© 2016 John Wiley & Sons Ltd Aims: PPARĪ± agonists are in current clinical use as hypolipidaemic agents and show significant antineoplastic effects in human glioblastoma models. To date however, the expression of PPARĪ± in large-scale glioblastoma datasets has not been examined. We aimed to investigate the expression of the transcription factor PPARĪ± in primary glioblastoma, the relationship between PPARĪ± expression and patientsā clinicopathological features and other molecular markers associated with gliomagenesis. Methods and results: With protein immunoblotting techniques and reverse transcription quantitative real-time PCR, PPARĪ± was found to be significantly overexpressed in glioblastoma compared with control brain tissue (P = 0.032 and P = 0.005). PPARA gene expression was found to be enriched in the classical glioblastoma subtype within The Cancer Genome Atlas (TCGA) dataset. Although not associated with overall survival when assessed by immunohistochemistry, cross-validation with the TCGA dataset and multivariate analyses identified PPARA gene expression as an independent prognostic marker for overall survival (P = 0.042). Finally, hierarchical clustering revealed novel, significant associations between high PPARA expression and a putative set of glioblastoma molecular mediators including EMX2, AQP4, and NTRK2. Conclusions: PPARĪ± is overexpressed in primary glioblastoma and high PPARA expression functions as an independent prognostic marker in the glioblastoma TCGA dataset. Further studies are required to explore genetic associations with high PPARA expression and to analyse the predictive role of PPARĪ± expression in glioblastoma models in response to PPARĪ± agonists
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