Current-carrying cosmic string loops 3D simulation: towards a reduction of the vorton excess problem

The dynamical evolution of superconducting cosmic string loops with specific equations of state describing timelike and spacelike currents is studied numerically. This analysis extends previous work in two directions: first it shows results coming from a fully three dimensional simulation (as opposed to the two dimensional case already studied), and it now includes fermionic as well as bosonic currents. We confirm that in the case of bosonic currents, shocks are formed in the magnetic regime and kinks in the electric regime. For a loop endowed with a fermionic current with zero-mode carriers, we show that only kinks form along the string worldsheet, therefore making these loops slightly more stable against charge carrier radiation, the likely outcome of either shocks or kinks. All these combined effects tend to reduce the number density of stable loops and contribute to ease the vorton excess problem. As a bonus, these effects also may provide new ways of producing high energy cosmic rays.Comment: 11 pages, RevTeX 4 format, 8 figures, submitted to PR

Threats to groundwater supplies from contamination in Sierra Leone, with special reference to Ebola care facilities

The outbreak of Ebola virus disease in West Africa in 2014 is the worst single outbreak recorded, and has resulted in more fatalities than all previous outbreaks combined. This outbreak has resulted in a large humanitarian effort to build new health care facilities, with associated water supplies. Although Ebola is not a water-borne disease, care facilities for Ebola patients may become sources of outbreaks of other, water-borne, diseases spread through shallow groundwater from hazard sources such as open defecation, latrines, waste dumps and burial sites to water supplies. The focus of this rapid desk study is to assess from existing literature the evidence for sub-surface transport of pathogens in the context of the hydrogeological and socio-economic environment of Sierra Leone. In particular, the outputs are to advise on the robustness of the evidence for an effective single minimum distance for lateral spacing between hazard sources and water supply, and provide recommendations for protecting water supplies for care facilities as well as other private and public water supplies in this region. Preliminary conclusions were: Considering the climate (heavy intense rainfall for 8 months), the hydrogeological conditions (prevalent shallow and rapidly fluctuating water tables, permeable tropical soils), the pervasive and widespread sources of hazards (very low improved sanitation coverage), and the widespread use of highly vulnerable water points there is little evidence that simply using an arbitrary lateral spacing between hazard sources and water point of 30 – 50 m would provide effective protection for groundwater points. An alternative framework that considers vertical as well as lateral separation and the integrity of the construction and casing of the deeper water points is recommended to protect water supplies from contamination by pathogens. The shallow aquifer, accessed by wells and springs, must be treated as highly vulnerable to pollution, both from diffuse sources and from localised sources. Diffuse pollution of groundwater from surface-deposited wastes including human excreta is likely to be at least as important as pollution from pit latrines and other point sources, given the low sanitation coverage in Sierra Leone. Even though conditions are not optimal for pathogen survival (e.g. temperatures of >25° C), given the very highly permeable shallow tropical soil zone, and the high potential surface and subsurface loading of pathogens, it is likely that shallow water sources are at risk from pathogen pollution, particularly during periods of intense rainfall and high water table conditions. Extending improved sanitation must be a high priority, in conjunction with improved vertical separation between hazard sources and water points, in order to reduce environmental contamination and provide a basis for improved public health. We recommend that risk assessments of water points are undertaken for health care facilities as soon as possible including: detailed sanitary inspections of water points within the 30 – 50 m radius suggested by the Ministry of Water Resource; assessments of the construction and integrity of the water points; a wider survey of contaminant load and rapid surface / sub surface transit routes within a wider 200 m radius of water points. Analysis of key water quality parameters and monitoring of water levels should be undertaken at each water point in parallel with the risk assessments. The translation of policy on water, sanitation and hygiene into implementation needs complementary research to understand key hydrogeological processes as well as barriers and failings of current practice for reducing contamination in water points. A baseline assessment of water quality status and sanitary risks for e.g. wells vs boreholes, improved vs unimproved sources in Sierra Leone is needed. Understanding the role of the tropical soil zone in the rapid migration of pollutants in the shallow subsurface, i.e. tracing rapid pathways, and quantifying residence times of shallow and deep groundwater systems are key knowledge gaps

Effect of Time and Amount of Nitrogen Uptake on Sugarbeet Growth and Yield

Sugarbeet (Beta vulgaris L.) root quality has been steadily decreasing since the early 1951's with increased use of N fertilizer. Since the extent of these decreases may be associated with the time and amount of N uptake, the objective of this study was to evaluate the effects of several rates and times of N fertilizer applications and N uptake by sugarbeets on seasonal growth rates, sucrose percentage and accumulation, dry matter production, and partitioning of the photosynthate. Sugarbeets were grown under field conditions on a Portneuf silt loam soil (Durixerollic Calciorthids, coarse-silty, mixed, mesic) near Twin Falls, Idaho, in 1977, using four N rates, each applied preplant, mid-June, mid-July, and mid-August. Root yields, sucrose concentration and yield, dry matter production, leaf area index, and plant N uptake were determined from samples taken throughout the season. Adding N fertilizer above that needed for optimum plant growth or delaying N application until midseason caused a greater proportion of the photosynthate to be used for increased top growth at the expense of dry matter and sucrose accumulation in the roots. Sucrose accumulation was maximum from late July until early September; therefore, during this period, addition of N and N uptake by the plant caused the greatest decrease in sucrose accumulation and production at harvest. Increasing N levels decreased sucrose concentrations during the season and at harvest because of 1) increased moisture level of roots, and 2) dry matter produced and accumulated in the roots having a decreased sucrose concentration. The rate of accumulation of stored sucrose was reduced by midseason N application, but stored sucrose was not used for increased growth of beet tops. Excess and late N applications also increased impurities in the beet root, decreasing extractability of stored sucrose, which further decreased refined sucrose production. Early application of N fertilizer at optimum levels should maximize refined sucrose production

Yield and Quality as Affected by Early and Late Fall and Spring Harvest of Sugarbeets

Sugarbeets (Beta vulgaris L.) in the intermountain areas of the western United States are normally planted in early spring and harvested during October with the advent of cool temperatures. The beet roots during this harvesting period are near their maximum yield and sucrose concentration. Temperatures are cool and suitable for storing excess roots in piles for later processing. The factory processing of beet roots is presently limited to the period between harvest and mid-February after which stored roots in piles deteriorate rapidly in quality with increased temperatures (2, 10, 16, 17). The closing of some sugar factories, and low prices currently received for other crops, has intensified demand by farm managers for increased acreage allotment for sugarbeets. Present low world sugar prices and the uncertainty of continued sugar legislation discourages the expansion of the cutting and processing facilities in factories. Methods and procedures are needed to increase the tonnage of beet roots that can be processed using existing equipment and facilities. The objective of this study was to evaluate methods and procedures where factories can increase the amount of beet roots processed with existing equipment by methods such as early and late fall and spring harvest of sugarbeets

Sugarbeet Yield and Seasonal Growth Characteristics as Affected by Hail Damage and Nitrogen Level

Sugarbeets (Beta vulgaris L.) grown in the western United States are subject to hailstorms that reduce yield and profits to the grower. A better understanding of growth characteristics before and after hail damage will enable growers to make correct decisions regarding soil and plant treatments to hasten recovery from hail damage and maximize sucrose yields

Effect of Mid-to Late-Season Water Stress on Sugarbeet Growth and Yield

Costs of irrigation (labor, water, and energy) and sometimes limited-late-season water are factors associated with the choice of crop and economic returns. Sugarbeets (Beta vulgaris L.) have shown certain tolerance to water stress, therefore the objective of this study was to evaluate growth rates and characteristics, sucrose accumulation, and N uptake by sugarbeets grown under mid to late-season soil water deficit and plant water stress. Sugarbeets were grown in a field experiment on a Portneuf silt loam soil (Durixerollic Calciorthids; coarse-silty, mixed, mesic) under normal irrigation until 15 July, after which further irrigation was terminated or reduced on two treatments during a 2-year period. Root yield, sucrose concentration, sucrose yield, plant N uptake, and petiole NO?-N were determined from samples taken throughout each season. These experiments demonstrated that very little, if any, sucrose yield reduction can be expected in the Idaho area if irrigations are discontinued after filling the soil profile with water about 1 August and if the soil contains at least 200 mm of available water to a soil depth of 160 cm. During dry years, there may be an advantage to applying a light irrigation about 1 month after water cutoff and to have sufficient surface soil water present at harvest to prevent loss of roots by breaking. Use of deficit water management during August, September, and October curtailed leaf growth, reduced leaf area when no longer needed, reduced N uptake from the soil, increased sucrose concentration in the beet root, and decreased fresh root yield. These effects on yields were mainly caused by dehydration of the beet tops and roots so sucrose production was scarcely affected even though only 74% of the normal irrigation water was applied. Limited irrigations reduced evapotranspiration rates because of drier surface soil and partial stomatal closure, thereby decreasing the rate of water extraction from the soil reservoir by the plant. Use of mid to late-season deficit water management could substantially reduce sugarbeet production costs in irrigated areas and economically benefit the consumer, producer, and manufacturer

Root and Sucrose Yields of Sugarbeets as Affected by Mid-to-Late-Season Water Stress

Investigations of the irrigation water requirement of sugarbeets (Beta vulgaris L.) in Arizona and California have shown that water stress several weeks before harvest of fall-planted beets reduces root yields but increases sucrose concentration (2,3). Their studies showed that, since soil and plant water stress late in the season did not significantly reduce sucrose production, irrigations could be discontinued 3 to 4 weeks before harvest for maximum water economy. Mid- to late-season water deficit studies on spring-planted sugarbeets at this Center in 1977 and 1978 clearly showed that sucrose yield was reduced very little in this area, if at all, if irrigations were discontinued after the soil profile was filled with water about 1 August or 10 to 12 weeks before harvest, on soil having a useable soil water reservoir of at least 200 mm (1) . However, if no rainfall occurs, a light irrigation about 1 month after water cutoff may be advantageous. The major difference between these two areas (Arizona-California and Idaho) is that in Arizona and California, potential evapotranspiration rates are higher and increasing when fall-planted beets are harvested; whereas in Idaho, potential rates are lower and decreasing when spring-planted beets are harvested. Allowing mid- to late-season water stress to develop in the Idaho area reduces irrigation water requirements by about 30% during August, September, and October when irrigation water and hydro-electric power for pumping are in shortest supply. Other recent investigations also show the drought tolerance of sugarbeets throughout the growing season ( 8, 11)

Cometary charge exchange diagnostics in UV and X‐ray

Since the initial discovery of cometary charge exchange emission, more than 20 comets have been observed with a variety of X‐ray and UV observatories. This observational sample offers a broad variety of comets, solar wind environments and observational conditions. It clearly demonstrates that solar wind charge exchange emission provides a wealth of diagnostics, which are visible as spatial, temporal, and spectral emission features. We review the possibilities and limitations of each of those in this contribution (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91138/1/335_ftp.pd

Edge states of graphene bilayer strip

The electronic structure of the zig-zag bilayer strip is analyzed. The electronic spectra of the bilayer strip is computed. The dependence of the edge state band flatness on the bilayer width is found. The density of states at the Fermi level is analytically computed. It is shown that it has the singularity which depends on the width of the bilayer strip. There is also asymmetry in the density of states below and above the Fermi energy.Comment: 9 page