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Search Results: 1 - 10 of 220877 matches for " C. Grant "
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The Impact of Water Table Drawdown and Drying on Subterranean Aquatic Fauna in In-Vitro Experiments
Christine Stumpp, Grant C. Hose
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078502
Abstract: The abstraction of groundwater is a global phenomenon that directly threatens groundwater ecosystems. Despite the global significance of this issue, the impact of groundwater abstraction and the lowering of groundwater tables on biota is poorly known. The aim of this study is to determine the impacts of groundwater drawdown in unconfined aquifers on the distribution of fauna close to the water table, and the tolerance of groundwater fauna to sediment drying once water levels have declined. A series of column experiments were conducted to investigate the depth distribution of different stygofauna (Syncarida and Copepoda) under saturated conditions and after fast and slow water table declines. Further, the survival of stygofauna under conditions of reduced sediment water content was tested. The distribution and response of stygofauna to water drawdown was taxon specific, but with the common response of some fauna being stranded by water level decline. So too, the survival of stygofauna under different levels of sediment saturation was variable. Syncarida were better able to tolerate drying conditions than the Copepoda, but mortality of all groups increased with decreasing sediment water content. The results of this work provide new understanding of the response of fauna to water table drawdown. Such improved understanding is necessary for sustainable use of groundwater, and allows for targeted strategies to better manage groundwater abstraction and maintain groundwater biodiversity.
Opportunities With Decay-At-Rest Neutrinos From Decay-In-Flight Neutrino Beams
C. Grant,B. R. Littlejohn
Physics , 2015,
Abstract: Neutrino beam facilities, like spallation neutron facilities, produce copious quantities of neutrinos from the decay at rest of mesons and muons. The viability of decay-in-flight neutrino beams as sites for decay-at-rest neutrino studies has been investigated by calculating expected low-energy neutrino fluxes from the existing Fermilab NuMI beam facility. Decay-at-rest neutrino production in NuMI is found to be roughly equivalent per megawatt to that of spallation facilities, and is concentrated in the facility's target hall and beam stop regions. Interaction rates in 5 and 60 ton liquid argon detectors at a variety of existing and hypothetical locations along the beamline are found to be comparable to the largest existing decay-at-rest datasets for some channels. The physics implications and experimental challenges of such a measurement are discussed, along with prospects for measurements at targeted facilities along a future Fermilab long-baseline neutrino beam.
Cropping frequency and N fertilizer effects on soil water distribution from spring to fall in the semiarid Canadian prairies  [PDF]
R. de Jong, C. A. Campbell, R. P. Zentner, P. Basnyat, B. Grant, R. Desjardins
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.23031
Abstract: In the semiarid Canadian prairies, water is the most limiting and nitrogen (N) the second most limiting factor influencing spring wheat (Triticum aestivum L.) production. The efficiency of water-and nitrogen use needs to be assessed in order to maintain this production system. The effects of cropping frequency and N fertilization on trends in soil water distribution and water use were quantified for an 18-yr (1967-1984) field experiment conducted on a medium textured Orthic Brown Chernozem (Aridic Haploboroll) in southwestern Saskatchewan, Canada. Soil water contents were measured eight times each year and plant samples were taken at five phenological growth stages. The treatments studied were continuous wheat (Cont W), summer fallow - wheat, F-(W) and summer fallow - wheat - wheat, F-W-(W) each receiving recommended rates of N and phosphorus (P) fertilizer, and (F)-W-W and (Cont W) each receiving only P fertilizer, with the examined rotation phase shown in parentheses. Soil water conserved under fallow during the summer months averaged 25 mm in the root zone, and was related to the initial water content of the soil, the amount of precipitation received, its distribution over time, and potential evapotranspiration. Under a wheat crop grown on fallow, soil water contents between spring and the five-leaf stage remained relatively constant at about 250 mm, but those under a stubble crop, with 40 mm lower spring soil water reserves, increased slightly until about the three-leaf stage. During the period of expansive crop growth (from the five-leaf to the soft dough stage) soil water was rapidly lost from all cropped phases at rates of 1.87 mm.day–1 for F-(W) (N+P), 1.23 mm.day–1 for Cont W (N+P) and 1.17 mm.day–1 for Cont W (+P). The initial loss was from the 0 - 0.3 m depth, but during the latter half of the growing season from deeper depths, although rarely from the 0.9 - 1.2 m depth. In very dry years (e.g., 1973, with 87 mm precipitation between spring and fall) summer fallow treatments lost water. In wet years with poor precipitation distribution (e.g., 1970, with 287 mm precipitation between spring and fall but 142 mm of this in one week between the three- and five-leaf stage) even cropped treatments showed evidence of leaching. The above-ground biomass water use efficiency for Cont W was 19.2 and 16.7 kg.ha–1.mm–1, respectively, for crops receiving (N+P) and P fertilizer only. Grain yield water use efficiency (8.91
Designing Relevant and Authentic Scenarios for Learning Clinical Communication in Dentistry Using the Calgary-Cambridge Approach  [PDF]
Vicki J. Skinner, Dimitra Lekkas, Tracey A. Winning, Grant C. Townsend
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326134
Abstract: A clinical communication curriculum based on the principles of the Calgary-Cambridge approach was developed during the revision of the 5-year Bachelor of Dental Surgery program (BDS) at The University of Adelaide, Australia. To provide experiential learning opportunities, a simulated patient (SP) program using clinical scenarios was developed. We aimed to design the scenarios to reflect communication demands that student clinicians commonly encounter, that integrated process and content, and which students would perceive as authentic and relevant. Scenarios were based on data from focus groups with recent graduates and interviews with clinic tutors. The scenarios combined content (e.g. medical history) and process (e.g. questioning and relationship skills) at a level suitable for junior students. Students evaluated scenario-based materials and SP activities in a survey comprising Likert-scale and open-ended questions. Students rated the materials and SP activities positively; open-ended comments supported the ratings. Scenario-based materials and activities based on student-clinicians’ experiences, were perceived as relevant, realistic, and useful for learning. A curriculum designed on Calgary-Cambridge principles helped address student learning needs at particular stages of their program.
Functional Characterization of the Octenol Receptor Neuron on the Maxillary Palps of the Yellow Fever Mosquito, Aedes aegypti
Alan J. Grant,Joseph C. Dickens
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021785
Abstract: 1-Octen-3-ol (octenol) is a common attractant released by vertebrates which in combination with carbon dioxide (CO2) attracts hematophagous arthropods including mosquitoes. A receptor neuron contained within basiconic sensilla on the maxillary palps of adult mosquitoes responds selectively to 1-octen-3-ol. Recently, an odorant receptor (AaegOR8) known to occur on the maxillary palps was expressed in a heterologous system and demonstrated to be selectively sensitive to (R)-(?)-1-octen-3-ol, one of two enantiomeric forms. Lesser responses were elicited by stimulation with the (S)-enantiomer and various structural analogs.
Multigene family isoform profiling from blood cell lineages
Grant Dewson, Edward C Conley, Peter Bradding
BMC Genomics , 2002, DOI: 10.1186/1471-2164-3-22
Abstract: Gene sequence alignment allowed determination of "islands" of amino acid homology, and sub-family "centred" priming permitted simultaneous co-amplification of each family member. Validation and cross-priming analysis was performed against a panel of cognate Kir channel clones. Radiolabelling and diagnostic restriction digestion of pooled PCR products enabled determination of distinct Kir gene expression profiles in pure populations of human neutrophils, eosinophils and lung mast cells, with conservation of Kir2.0 isoforms amongst the leukocyte subsets. We also identified a Kir2.0 channel product, which may potentially represent a novel family member.We have developed a novel, rapid and flexible strategy for the determination of gene family isoform composition in any cell type with the additional capacity to detect hitherto unidentified family members and verified its application in a study of Kir channel isoform expression in human leukocytes.Identification of gene family expression profiles in individual cells is an important means of describing signal transduction selectivity and specificity. Thus, as the human genome project reaches completion [1], much emphasis is being placed on determining how combinations of gene expression influence complex traits and disease susceptibility. For families of receptors, channels, enzymes or other proteins that are potential therapeutic targets, the ability to identify cell-specific isoform expression from the many potentially encoded by the genome is crucial. Since coding portions of the human genome will soon be entirely determined, simple typing procedures need to be developed that accommodate all isoforms within known gene families. Conventional approaches to isoform profiling are based on synthesis of multiple sets of "gene-specific" oligonucleotides priming multiple reverse transcriptase-polymerase chain reactions (RT-PCR). However, because of the small amounts of mRNA sampled from many clinically-derived tissue samples,
Bepaling van harttempovariasie: ’n vergelyking tussen direkte bepaling vanaf V6 van die EKG en tyddomein, frekwensiedomein en nielineêre analise
C. Grant,P. J. Becker,M. Viljoen
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2006, DOI: 10.4102/satnt.v25i2.148
Abstract: Tydens die normale funksionering van die hart fluktueer die intervalle tussen opeenvolgende hartslae (R-R-intervalle) rondom ’n gemiddelde waarde. Hierdie fluktuering staan bekend as harttempovariasie (HTV). Verskillende metodes word gebruik om HTV te bepaal maar dit is nie bekend tot watter mate daar ooreenstemming is tussen die resultate van die verskillende metodes waarmee HTV ondersoek word nie. In hierdie studie word HTV, soos bepaal vanaf die EKG, vergelyk met resultate soos verkry met behulp van tyddomeinanalise, frekwensiedomeinanalise, Poincaré-grafieke en fraktaalanalise. Die resultate van hierdie studie toon dat, in individue met laer HTV, met tyddomeinanalise, frekwensiedomeinanalise, Poincaré en Alfa 1 van fraktale Abstract Determining heart rate variation: a comparison between direct results from V6 of the ECG and time domain, frequency domain and non-liniar analysis Oscillation around a mean value is found in the intervals between consecutive heartbeats (R-R intervals). This oscillation is known as heart rate variability (HRV). Various methods can be used to estimate HRV, but the extent to which agreement exists between the results obtained by the different methods is not known. In this study HRV, as determined directly from the ECG, is compared to results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis. Results showed that, in individuals with low HRV values, the results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and alpha 1 of fractal analysis are comparable to those calculated directly from the ECG. However, time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis are less sensitive than direct ECG measurements in individuals with higher HRV.
Sleep Disturbances in Pediatric Bipolar Disorder: A Comparison between Bipolar I and Bipolar NOS
Argelinda Baroni,Mariely Hernandez,Marie C. Grant
Frontiers in Psychiatry , 2012, DOI: 10.3389/fpsyt.2012.00022
Abstract: Introduction: The diagnosis of bipolar disorder (BD) in youths has been controversial, especially for the subtype BD not otherwise specified (BD-NOS). In spite of growing evidence that sleep is a core feature of BD, few studies characterize and compare sleep disturbances in youth with BD type I (BD-I) and BD-NOS. Sleep disturbances are frequently reported in clinical descriptions of children and adolescents with BD, however the reporting of the frequency and characteristics of sleep symptoms in youth with BD-NOS and BD-I during episodes remain poor. This study compares symptom of sleep disturbance as occurring in manic and depressive episodes in BD-I and BD-NOS youth using Kiddie-schedule for affective disorders and schizophrenia, present and lifetime version (K-SADS-PL) interview data. The study also addresses whether symptoms of sleep disturbance vary in different age groups. Materials and Methods: The sample consisted of 70 children and adolescent outpatients at an urban specialty clinic (42M/28F, 10.8 ± 3.6 years old) including 24 BD-I and 46 BD-NOS assessed using K-SADS-PL-parent interview. Results: Sleep disturbances including insomnia and decreased need for sleep were reported by 84.3% of the sample. Enuresis was diagnosed in 27% of sample. There were no significant differences in frequency of sleep symptoms between BD-I and BD-NOS. Regardless of BD subtype, current functioning was negatively correlated with decreased need for sleep but not insomnia, and regardless of BD subtype. Conclusion: The majority of youth with BD presents with sleep symptoms during mood episodes. BD-NOS presents with the same proportion of sleep symptoms as BD-I in our sample.
The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability
Grant M. Kennedy,Mark C. Wyatt
Physics , 2013, DOI: 10.1093/mnras/stt900
Abstract: We present the first characterisation of the 12um warm dust ("exo-Zodi") luminosity function around Sun-like stars, focussing on the dustiest systems that can be identified by WISE. We detect six new warm dust candidates, five of which have unknown ages. We show that the dustiest old (>Gyr) systems like BD+20 307 are 1 in 10,000 occurrences. Bright warm dust is more common around young (<120Myr) systems, with a ~1% occurrence rate. We show that a two component in situ model where all stars have initially massive warm disks and in which warm debris is also generated at some random time along the stars' main-sequence lifetime, perhaps due to a collision, can explain the observations. However, if all stars only have initially massive warm disks these would not be visible at Gyr ages, and random collisions on the main-sequence are too infrequent to explain the high disk occurrence rate for young stars. That is, neither component can explain the observations on their own. Despite these conclusions, we cannot rule out an alternative model in which comets are scattered from outer regions because the distribution of systems with the appropriate dynamics is unknown. Our in situ model predicts the fraction of stars with exo-Zodi bright enough to cause problems for future exo-Earth imaging attempts is at least ~10%, and is higher for populations of stars younger than a few Gyr. This prediction of ~10% applies to old stars because bright systems like BD+20 307 imply a population of fainter systems that were once bright but are now decaying through fainter levels. Our prediction should be strongly tested by the Large Binocular Telescope Interferometer, providing valuable input for more detailed evolution models. A detection fraction lower than our prediction could indicate that the hot dust in systems like BD+20 307 has a cometary origin due to the quirks of the planetary dynamics.
A potential sterile neutrino search utilizing spectral distortion in a two-reactor/one-detector configuration
M. Bergevin,C. Grant,R. Svoboda
Physics , 2013,
Abstract: There is an observed deficit of about 6\% in the expected rate of anti-neutrino interactions when averaging over many different reactor experiments. While the significance of the deficit is low (98.6 \% CL), there is speculation that a non-interacting "sterile" neutrino could be the cause. In this paper we explore the possibility of a two-reactor/one-detector experiment at intermediate distances (100-500 meters) to look for a sterile neutrino in the mass range implied by this deficit. A method for probing $\Delta m^2$ phase space is developed using interference patterns between two oscillated spectra at different baselines. This method is used to investigate the potential sensitivity of the Double Chooz experiment, which has a single Near Detector at distances of 351 m and 465 m from two reactors of identical design. We conclude that Double Chooz could investigate sterile neutrino in the $\Delta m^{2}$ range of 0.002 to 0.5 eV$^2$ over 5 years of near detector running.
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