2,539 research outputs found
Gauge Invariant Propagators and States in Quantum Electrodynamics
We study gauge invariant states in QED, where states are understood in terms
of data living on the boundary of gauge invariant path-integrals. This is done
for both scalar and spinor QED, and for boundaries that are either time slices,
or the boundaries of a 'causal diamond'. We discuss both the case where the
gauge field falls off to zero at the boundaries, and the case of 'large gauge
transformations', where it remains finite at the boundaries. The dynamics are
discussed using the gauge-invariant propagator, describing motion of both the
particles and the field between the boundaries. We demonstrate how the
path-integral naturally generates a 'Coulomb-field' dressing factor for states
living on time-slices, and how this is done without fixing any gauge. We show
that the form of the dressing depends only on the nature of the boundaries. We
also derive the analogous dressing for states defined on null infinity, showing
both its Coulombic parts as well as soft-photon parts.Comment: 24 pages, 3 figure
Political participation: the vocational motivations of Labour party employees
Party employees are an under-researched group in political science. This article begins to address this oversight by examining Labour Party employees using new quantitative and qualitative data. It argues that party employment should be regarded as a form of political participation and as a consequence, existing models of political participation can be utilised to help explain why people work for political parties. After testing these propositions, the article concludes that existing models are indeed helpful in explaining the motivations for party employment
Deep dielectric charging of regolith within the Moon\u27s permanently shadowed regions
Abstract Energetic charged particles, such as galactic cosmic rays (GCRs) and solar energetic particles (SEPs), can penetrate deep within the lunar surface, resulting in deep dielectric charging. This charging process depends on the GCR and SEP currents, as well as on the regolith\u27s electrical conductivity and permittivity. In permanently shadowed regions (PSRs) near the lunar poles, the discharging timescales are on the order of a lunation (∼20 days). We present the first predictions for deep dielectric charging of lunar regolith. To estimate the resulting subsurface electric fields, we develop a data-driven, one-dimensional, time-dependent model. For model inputs, we use GCR data from the Cosmic Ray Telescope for the Effects of Radiation on board the Lunar Reconnaissance Orbiter and SEP data from the Electron, Proton, and Alpha Monitor on the Advanced Composition Explorer. We find that during the recent solar minimum, GCRs create persistent electric fields up to ∼700 V/m. We also find that large SEP events create transient but strong electric fields (≥106 V/m) that may induce dielectric breakdown. Such breakdown would likely result in significant modifications to the physical and chemical properties of the lunar regolith within PSRs. Key Points Energetic charged particles deep dielectrically charge the lunar regolithWe model the resulting subsurface electric fieldsThe electric fields may be great enough to induce dielectric breakdown
Dielectric breakdown weathering of the Moon\u27s polar regolith
Abstract
Galactic cosmic rays and solar energetic particles (SEPs) can charge the Moon\u27s subsurface, a process expected to be particularly important in the polar regions. Experiments have shown that sufficient fluences (i.e., time-integrated fluxes) of energetic charged particles can cause dielectric breakdown, in which the electric field rapidly vaporizes small, filamentary channels within a dielectric. Lunar regolith has both the characteristics and, in some polar locations, the environment needed to make breakdown likely. We combine the Jet Propulsion Laboratory proton fluence model with temperature measurements from the Lunar Reconnaissance Orbiter\u27s (LRO\u27s) Diviner instrument and related temperature modeling to estimate how often breakdown occurs in the polar regions. We find that all gardened regolith within permanently shadowed regions (PSRs) has likely experienced up to 2×106 SEP events capable of causing breakdown, while the warmest polar regions have experienced about 2 orders of magnitude fewer events. We also use measurements from the Cosmic Ray Telescope for the Effects of Radiation on LRO to show that at least two breakdown-inducing events may have occurred since LRO arrived at the Moon in 2009. Finally, we discuss how such “breakdown weathering” may increase the percentage of fine and monomineralic grains within PSRs; explain the presence of so-called “fairy castle” regolith structures; and contribute to other low-albedo features detected by LRO\u27s Lyman Alpha Mapping Project, possibly establishing a correlation between these features and the average temperatures within craters that are only partly in permanent shadow
Comparative absorption of curcumin formulations
BACKGROUND: The potential health benefits of curcumin are limited by its poor solubility, low absorption from the gut, rapid metabolism and rapid systemic elimination. The purpose of this study was the comparative measurement of the increases in levels of curcuminoids (curcumin, demethoxycurcumin, bisdemethoxycurcumin) and the metabolite tetrahydrocurcumin after oral administration of three different curcumin formulations in comparison to unformulated standard. METHODS: The relative absorption of a curcumin phytosome formulation (CP), a formulation with volatile oils of turmeric rhizome (CTR) and a formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants (CHC) in comparison to a standardized curcumin mixture (CS) was investigated in a randomized, double-blind, crossover human study in healthy volunteers. Samples were analyzed by HPLC-MS/MS. RESULTS: Total curcuminoids appearance in the blood was 1.3-fold higher for CTR and 7.9-fold higher for CP in comparison to unformulated CS. CHC showed a 45.9-fold higher absorption over CS and significantly improved absorption over CP (5.8-fold) and CTR (34.9-fold, all p < 0.001). CONCLUSION: A formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants significantly increases curcuminoid appearance in the blood in comparison to unformulated standard curcumin CS, CTR and CP
Smartphone Medical Applications Useful for the Rural Practitioner
Like other similarly situated rural states, West Virginia’s patients and practitioners often experience access barriers to current medical expertise for multiple disciplines. This article was generated to help bridge this gap and highlights the best-rated mobile medical applications (Apps) for smartphone use. From finding drug interactions and dosing schedules to discussing patients in HIPAA-compliant formats, Apps are becoming integral to the practice of 21st Century medicine. The increased use of these Apps by physicians-in-training and established practitioners highlights the shift from reliance upon the medical library to the easy to use mobile-based technology platforms. This article provides our practitioners, physician extenders, medical trainees, and office staff a guide to access and assess the utility of some of the best rated medical and HIPAA compliant Apps
Farmers Markets and the Local Food System: The Case of Gettysburg, Pennsylvania
In order to examine and obtain a better understanding of the local food system within Adams County, Pennsylvania, this study explores the characteristics and perspectives of the customers and vendors at the farmers markets in Gettysburg, Pennsylvania. Survey findings from the Gettysburg Farmers Market and the three Adams County Farmers Markets include customer demographic information, perspectives and shopping behavior as well as vendor product information, farm size and location and preference for market management. Introductory background information on the Farm Bill and the influence of agricultural practices on the environment, human health and nutrition and the relationship between farmers markets and the local economy are offered in order to emphasize the value of a well-managed local food system. Conclusions provide evidence that lower income and lower education levels are not sufficiently represented at all the markets and food stamp programs are being underutilized. This study suggests employing additional marketing to target underrepresented demographic groups, public transportation to potentially inaccessible market locations and increased advertisement and encouragement of food stamp programs at all markets in order to expand the customer base and increase access to healthy, local foods for less advantaged citizens. The results from this study are intended to offer evidence that will promote and facilitate market management, strengthen customer/vendor relationships and encourage better ties between the local community and local food systems at the farmers markets within Gettysburg in Adams County, Pennsylvania
Precise Detections of Solar Particle Events and a New View of the Moon
We have invented a new method for detecting solar particle events using data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO). Using a simple function of the total particle detection rates from four of CRaTER’s six detectors, we can precisely identify solar energetic particle event periods in the CRaTER data archive. During solar quiet periods we map the distribution of a mare‐associated mixture of elements in the lunar regolith using this new method. The new map of the moon probably reflects an as‐yet unknown combination of lunar albedo protons, neutrons, and gamma rays, and most closely resembles Lunar Prospector maps of gamma rays characteristic of thorium and iron. This result will lead to multiple follow‐up studies of lunar albedo particles and may also contribute to the study of diurnally varying hydrogenation of the lunar regolith.Key PointsThe CRaTER instrument on LRO can detect and quantify small solar particle events with a simple new analysis techniqueOur new lunar map of albedo radiation resembles gamma ray maps from Lunar ProspectorFollow‐up studies will investigate contributions from neutrons, protons, and gamma rays, and signatures of hydrogen in lunar regolithPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152796/1/grl60033_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152796/2/grl60033.pd
Drivers of declining CO2 emissions in 18 developed economies
Global emissions of carbon dioxide (CO 2 ) from fossil fuels and industry increased by 2.2% per year on average between 2005 and 2015 1 . Global emissions need to peak and decline rapidly to limit climate change to well below 2 °C of warming 2,3 , which is one of the goals of the Paris Agreement 4 . Untangling the reasons underlying recent changes in emissions trajectories is critical to guide efforts to attain those goals. Here we analyse the drivers of decreasing CO 2 emissions in a group of 18 developed economies that have decarbonized over the period 2005–2015. We show that within this group, the displacement of fossil fuels by renewable energy and decreases in energy use explain decreasing CO 2 emissions. However, the decrease in energy use can be explained at least in part by a lower growth in gross domestic product. Correlation analysis suggests that policies on renewable energy are supporting emissions reductions and displacing fossil fuels in these 18 countries, but not elsewhere, and that policies on energy efficiency are supporting lower energy use in these 18 countries, as well as more widely. Overall, the evidence shows that efforts to reduce emissions are underway in many countries, but these efforts need to be maintained and enhanced by more stringent policy actions to support a global peak in emissions followed by global emissions reductions in line with the goals of the Paris Agreement 3
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