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Search Results: 1 - 10 of 12693 matches for " Philip Jones "
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Pushing, Pulling, Twisting, Stretching: the Power of Light under the Microscope
Philip H. Jones
Opticon1826 , 2009, DOI: 10.5334/opt.070907
Abstract: Of the many uses we have for light such as illumination or digital communication, perhaps the most surprising is physical manipulation of matter. Holding and moving objects without touching them may seem like the stuff of science fiction, but a profound understanding of the interaction between light and matter can make this a reality, at least on the microscopic scale. Since its invention, the technique of ‘optical trapping’ has evolved into a tool with applications beyond the narrow scope of physics, and in particular, has enabled remarkable discoveries in biology and medicine.
Spatial Modeling of Risk in Natural Resource Management
Peter Jones,Philip K. Thornton
Ecology and Society , 2002,
Abstract: Making decisions in natural resource management involves an understanding of the risk and uncertainty of the outcomes, such as crop failure or cattle starvation, and of the normal spread of the expected production. Hedging against poor outcomes often means lack of investment and slow adoption of new methods. At the household level, production instability can have serious effects on income and food security. At the national level, it can have social and economic impacts that may affect all sectors of society. Crop models such as CERES-Maize are excellent tools for assessing weather-related production variability. WATBAL is a water balance model that can provide robust estimates of the potential growing days for a pasture. These models require large quantities of daily weather data that are rarely available. MarkSim is an application for generating synthetic daily weather files by estimating the third-order Markov model parameters from interpolated climate surfaces. The models can then be run for each distinct point on the map. This paper examines the growth of maize and pasture in dryland agriculture in southern Africa. Weather simulators produce independent estimates for each point on the map; however, we know that a spatial coherence of weather exists. We investigated a method of incorporating spatial coherence into MarkSim and show that it increases the variance of production. This means that all of the farmers in a coherent area share poor yields, with important consequences for food security, markets, transport, and shared grazing lands. The long-term aspects of risk are associated with global climate change. We used the results of a Global Circulation Model to extrapolate to the year 2055. We found that low maize yields would become more likely in the marginal areas, whereas they may actually increase in some areas. The same trend was found with pasture growth. We outline areas where further work is required before these tools and methods can address natural resource management problems in a comprehensive manner at local community and policy levels.
Geometric derivation of the quantum speed limit
Philip J. Jones,Pieter Kok
Physics , 2010, DOI: 10.1103/PhysRevA.82.022107
Abstract: The Mandelstam-Tamm and Margolus-Levitin inequalities play an important role in the study of quantum mechanical processes in Nature, since they provide general limits on the speed of dynamical evolution. However, to date there has been only one derivation of the Margolus-Levitin inequality. In this paper, alternative geometric derivations for both inequalities are obtained from the statistical distance between quantum states. The inequalities are shown to hold for unitary evolution of pure and mixed states, and a counterexample to the inequalities is given for evolution described by completely positive trace-preserving maps. The counterexample shows that there is no quantum speed limit for non-unitary evolution.
The Renormalized Thermal Mass with Non-Zero Charge Density
H. F. Jones,Philip Parkin
Physics , 2000, DOI: 10.1016/S0550-3213(00)00662-3
Abstract: The linear $\delta$ expansion is used to obtain corrections up to O$(\delta^2)$ to the self-energy for a complex scalar field theory with a $\lambda (\phi^{\star}\phi)^2$ interaction at high temperature and non-zero charge density. The calculation is done in the imaginary-time formalism via the Hamiltonian form of the path integral. Nonperturbative results are generated by a systematic order by order variational procedure and the dependence of the critical temperature on the chemical potential $\mu$ is obtained.
Hes6 Is Required for the Neurogenic Activity of Neurogenin and NeuroD
Kasumi Murai,Anna Philpott,Philip H. Jones
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0027880
Abstract: In the embryonic neural plate, a subset of precursor cells with neurogenic potential differentiates into neurons. This process of primary neurogenesis requires both the specification of cells for neural differentiation, regulated by Notch signaling, and the activity of neurogenic transcription factors such as neurogenin and NeuroD which drive the program of neural gene expression. Here we study the role of Hes6, a member of the hairy enhancer of split family of transcription factors, in primary neurogenesis in Xenopus embryos. Hes6 is an atypical Hes gene in that it is not regulated by Notch signaling and promotes neural differentiation in mouse cell culture models. We show that depletion of Xenopus Hes6 (Xhes6) by morpholino antisense oligonucleotides results in a failure of neural differentiation, a phenotype rescued by both wild type Xhes6 and a Xhes6 mutant unable to bind DNA. However, an Xhes6 mutant that lacks the ability to bind Groucho/TLE transcriptional co-regulators is only partly able to rescue the phenotype. Further analysis reveals that Xhes6 is essential for the induction of neurons by both neurogenin and NeuroD, acting via at least two distinct mechanisms, the inhibition of antineurogenic Xhairy proteins and by interaction with Groucho/TLE family proteins. We conclude Xhes6 is essential for neurogenesis in vivo, acting via multiple mechanisms to relieve inhibition of proneural transcription factor activity within the neural plate.
Assessment of Maximum Possible Urbanization Influences on Land Temperature Data by Comparison of Land and Marine Data around Coasts
Dimitrios A. Efthymiadis,Philip D. Jones
Atmosphere , 2010, DOI: 10.3390/atmos1010051
Abstract: Global surface temperature trends, based on land and marine data, show warming of about 0.8 °C over the last 100 years. This rate of warming is sometimes questioned because of the existence of Urban Heat Islands (UHIs). In this study we compare the rate of temperature change estimated from measurements of land and marine temperatures for the same grid squares using 5° by 5° latitude/longitude grid-box datasets. For 1951–2009 the ‘land’ average warmed by 0.02 °C decade ?1 relative to the ‘sea surface temperature’ (SST) average. There were regional contrasts in the trends of land/sea temperature differences: the land warmed at a greater rate compared to the SST for regions north of 20°S, but the opposite occurred further south. Given strong forcing of the climate system, we would expect the land to change more rapidly than the ocean, so the differences represent an upper limit to the urbanization effect.
The perceived impact of location privacy: A web-based survey of public health perspectives and requirements in the UK and Canada
Philip AbdelMalik, Maged Boulos, Ray Jones
BMC Public Health , 2008, DOI: 10.1186/1471-2458-8-156
Abstract: Perceptions on the impact of privacy were collected through a web-based survey administered between November 2006 and January 2007. The survey targeted government, non-government and academic GIS labs and research groups involved in public health, as well as public health units (Canada), ministries, and observatories (UK). Potential participants were invited to participate through personally addressed, standardised emails.Of 112 invitees in Canada and 75 in the UK, 66 and 28 participated in the survey, respectively. The completion proportion for Canada was 91%, and 86% for the UK. No response differences were observed between the two countries. Ninety three percent of participants indicated a requirement for personally identifiable data (PID) in their public health activities, including geographic information. Privacy was identified as an obstacle to public health practice by 71% of respondents. The overall self-rated median score for knowledge of privacy legislation and policies was 7 out of 10. Those who rated their knowledge of privacy as high (at the median or above) also rated it significantly more severe as an obstacle to research (P < 0.001). The most critical cause cited by participants in both countries was bureaucracy.The clash between PID requirements – including granular geography – and limitations imposed by privacy and its associated bureaucracy require immediate attention and solutions, particularly given the increasing utilisation of GIS in public health. Solutions include harmonization of privacy legislation with public health requirements, bureaucratic simplification, increased multidisciplinary discourse, education, and development of toolsets, algorithms and guidelines for using and reporting on disaggregate data.Although "place" has been coined one of the three pillars of epidemiological data, only relatively recently has it garnered significant attention in the public health field, as Geographic Information Systems (GIS) have increasingly becom
Consequence for Wavefunction Collapse Model of the Sudbury Neutrino Observatory Experiment
Gordon Jones,Philip Pearle,James Ring
Physics , 2004, DOI: 10.1023/B:FOOP.0000044101.51344.93
Abstract: It is shown that data on the dissociation rate of deuterium obtained in an experiment at the Sudbury Neutrino Observatory provides evidence that the Continuous Spontaneous Localization wavefunction collapse model should have mass--proportional coupling to be viable.
Comparison of Five Tillage Systems in Coastal Plain Soils for Cotton Production  [PDF]
Ahmad Khalilian, Michael A. Jones, Philip J. Bauer, Michael W. Marshall
Open Journal of Soil Science (OJSS) , 2017, DOI: 10.4236/ojss.2017.710018
Abstract: Soil compaction management in the southeastern USA typically relies heavily on the practice of annual deep tillage. Strip tillage systems have shown considerable promise for reducing energy and labor requirements, equipment costs, soil erosion, and cotton plant damage from blowing sand. Replicated field trials were conducted for three years in South Carolina, to compare the performance of three different strip tillage systems to conventional tillage and no-till methods. A second objective was to investigate whether the frequency of deep tillage can be reduced by planting cotton directly using controlled wheel traffic into the previous year’s subsoiler furrow. Tillage treatments included: conventional tillage (disk-subsoil-bed), straight shank strip-till, bent-leg shank strip-till (Paratill), bent-leg shank strip till (Terra Max), and no-till. Deep tillage was performed in all plots the first year. In years two and three, the plots were split and half received annual deep tillage and the other half were not deep tilled either year. Tillage methods were compared side by side with and without irrigation. Deep tillage reduced soil compaction and increased taproot length and cotton yields than the no-till system. There was no difference in cotton lint yield between the strip-till systems and conventional tillage in either dry land or irrigated plots. Deep tillage increased cotton lint yields compared to no-till. There was no difference in lint yield between plots which were deep-tilled in all three years with those which had tillage operation only in first year of the test. Dry matter partitioning at first bloom was reduced in plant height, total dry weight, and leaf area in strip-till and no-till production systems compared to the conventional tillage system. The results suggest that all three strip tillage systems are equally effective for cotton production and that annual deep tillage is not necessary if controlled traffic is employed.
Intestinal Activation of Notch Signaling Induces Rapid Onset Hepatic Steatosis and Insulin Resistance
Joanna C. Fowler,Vincent R. Zecchini,Philip H. Jones
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020767
Abstract: Here we investigate the effects of expressing an activated mutant of Notch (ICD-E) in an inducible transgenic mouse model. Hepatic expression of ICD-E in adult animals has no detectable phenotype, but simultaneous induction of ICD-E in both the liver and small intestine results in hepatic steatosis, lipogranuloma formation and mild insulin resistance within 96 hours. This supports work that suggests that fatty liver disease may result from disruption of the gut-liver axis. In the intestine, ICD-E expression is known to produce a transient change in the proportion of goblet cells followed by shedding of the recombinant epithelium. We report additional intestinal transcriptional changes following ICD-E expression, finding significant transcriptional down-regulation of rpL29 (ribosomal protein L29), which is implicated in the regulation of intestinal flora. These results provide further evidence of a gut-liver axis in the development of fatty liver disease and insulin resistance and validate a new model for future studies of hepatic steatosis.
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