21,091 research outputs found
The composition of corotating energetic particle streams
The relative abundances of 1.5 to 23 MeV/nucleon ions in corotating nucleon streams were compared with ion abundances in particle events associated with solar flares and with solar and solar wind abundances. He/O and C/O ratios were found to be a factor of the order two to three times greater in corotating streams than in flare associated events. The distribution of H/He ratios in corotating streams was found to be much narrower and of lower average value than in flare associated events. H/He in corotating energetic particle streams compared favorably both in lack of variability and numerical value to H/He in high speed solar wind plasma streams. This comparison suggested that the source population for the corotating energetic particles was the solar wind
New Q-ball Solutions in Gauge-Mediation, Affleck-Dine Baryogenesis and Gravitino Dark Matter
Affleck-Dine (AD) baryogenesis along a d=6 flat direction in gauge-mediated
supersymmetry-breaking (GMSB) models can produce unstable Q-balls which
naturally have field strength similar to the messenger scale. In this case a
new kind of Q-ball is formed, intermediate between gravity-mediated and
gauge-mediated type. We study in detail these new Q-ball solutions, showing how
their properties interpolate between standard gravity-mediated and
gauge-mediated Q-balls as the AD field becomes larger than the messenger scale.
It is shown that E/Q for the Q-balls can be greater than the nucleon mass but
less than the MSSM-LSP mass, leading to Q-ball decay directly to Standard Model
fermions with no MSSM-LSP production. More significantly, if E/Q is greater
than the MSSM-LSP mass, decaying Q-balls can provide a natural source of
non-thermal MSSM-LSPs, which can subsequently decay to gravitino dark matter
without violating nucleosynthesis constraints. The model therefore provides a
minimal scenario for baryogenesis and gravitino dark matter in the
gauge-mediated MSSM, requiring no new fields.Comment: 13 pages, 9 figures. Some corrections and additional discussion.
Version published in JCA
Deterministic dense coding and entanglement entropy
We present an analytical study of the standard two-party deterministic
dense-coding protocol, under which communication of perfectly distinguishable
messages takes place via a qudit from a pair of non-maximally entangled qudits
in pure state |S>. Our results include the following: (i) We prove that it is
possible for a state |S> with lower entanglement entropy to support the sending
of a greater number of perfectly distinguishable messages than one with higher
entanglement entropy, confirming a result suggested via numerical analysis in
Mozes et al. [Phys. Rev. A 71 012311 (2005)]. (ii) By explicit construction of
families of local unitary operators, we verify, for dimensions d = 3 and d=4, a
conjecture of Mozes et al. about the minimum entanglement entropy that supports
the sending of d + j messages, j = 2, ..., d-1; moreover, we show that the j=2
and j= d-1 cases of the conjecture are valid in all dimensions. (iii) Given
that |S> allows the sending of K messages and has the square roof of c as its
largest Schmidt coefficient, we show that the inequality c <= d/K, established
by Wu et al. [ Phys. Rev. A 73, 042311 (2006)], must actually take the form c <
d/K if K = d+1, while our constructions of local unitaries show that equality
can be realized if K = d+2 or K = 2d-1.Comment: 19 pages, 2 figures. Published versio
The Influence of Formulation, Buffering, pH and Divalent Cations on the Activity of Endothall on Hydrilla.
Endothall has been used as an aquatic herbicide for more
than 40 years and provides very effective weed control of
many weeds. Early research regarding the mechanism-of-action
of endothall contradicts the symptomology normally associated
with the product. Recent studies suggest endothall
is a respiratory toxin but the mechanism-of-action remains
unknown. To further elucidate the activity of endothall, several
endothall formulations were evaluated for their effects
on ion leakage, oxygen consumption and photosynthetic oxygen
evolution from hydrilla shoot tips. The influence of pH,
buffering and divalent cations was also evaluated. (PDF contains 6 pages.
Methane emissions from western Siberian wetlands: heterogeneity and sensitivity to climate change
The prediction of methane emissions from high-latitude wetlands is important given concerns about their sensitivity to a warming climate. As a basis for the prediction of wetland methane emissions at regional scales, we coupled the variable infiltration capacity macroscale hydrological model (VIC) with the biosphereâenergy-transferâhydrology terrestrial ecosystem model (BETHY) and a wetland methane emissions model to make large-scale estimates of methane emissions as a function of soil temperature, water table depth, and net primary productivity (NPP), with a parameterization of the sub-grid heterogeneity of the water table depth based on TOPMODEL. We simulated the methane emissions from a 100 km Ă 100 km region of western Siberia surrounding the Bakchar Bog, for a retrospective baseline period of 1980â1999 and have evaluated their sensitivity to increases in temperature of 0â5 °C and increases in precipitation of 0â15%. The interactions of temperature and precipitation, through their effects on the water table depth, played an important role in determining methane emissions from these wetlands. The balance between these effects varied spatially, and their net effect depended in part on sub-grid topographic heterogeneity. Higher temperatures alone increased methane production in saturated areas, but caused those saturated areas to shrink in extent, resulting in a net reduction in methane emissions. Higher precipitation alone raised water tables and expanded the saturated area, resulting in a net increase in methane emissions. Combining a temperature increase of 3 °C and an increase of 10% in precipitation to represent climate conditions that may pertain in western Siberia at the end of this century resulted in roughly a doubling in annual emissions
Thermomechanical behavior of plasma-sprayed ZrO2-Y2O3 coatings influenced by plasticity, creep and oxidation
Thermocycling of ceramic-coated turbomachine components produces high thermomechanical stresses that are mitigated by plasticity and creep but aggravated by oxidation, with residual stresses exacerbated by all three. These residual stresses, coupled with the thermocyclic loading, lead to high compressive stresses that cause the coating to spall. A ceramic-coated gas path seal is modeled with consideration given to creep, plasticity, and oxidation. The resulting stresses and possible failure modes are discussed
Environmental Monitoring on Research Centres and Large Farms Using Spatial Data Management Tools.
End of Project ReportThe objective of project 4480 was to build an environmental
management system by using a visual or map based approach to
develop new ways to manage environmental data on a large farm or an
estate of several farms. Geographic information system (GIS)
techniques are extremely powerful, but they tend to be complex, and
often require a high degree of skill and training in order to use them.
Using systems analysis, the fundamental environmental management
data were identified and a simplified spatial approach was developed to
manage these environmental data. Johnstown Castle Research Centre consists of three farms,
ornamental grounds, forests, lakes and streams. A set of database
tables was generated to hold farm environmental data on these farms.
These included:
annual management summary data giving the average number of
different types of animals, the amount of organic manure and N,
P and K nutrients produced by them, fertiliser purchases, organic
and chemical nutrient usage on the farm, achievement of nutrient
management planning targets, etc.
monthly livestock information recording the numbers of livestock
of different types for the three farms, together with management
comments on the changes and transfer that take place over the
month,
detailed land use and nutrient use information for each field or
plot on the estate,
recent soil analyses information for the experimental plots,
analysis results of recent water samples which are taken regularly
at sampling points throughout the estate. The topographical, soil and site features were digitised, in order to
collect information on the overall and individual farm boundaries. This
included roads, hedges and ditches, streams, rivers and lakes, the
buildings and most particularly, the boundaries of all field and
experimental plots. When the digitisation was complete, a set of
bespoke programs was built, using the GIS system, ArcView. To make
the system "user friendly", the menu system was customised by
removing complex features; retaining only those buttons and menu
options that served a purpose useful to the application. The programs
were unified into a PC system called Johnstown Castle Environmental
Monitoring System or JCEMS. For the future, it is envisaged that the maps and spatial techniques
will be embodied into an Access database system and developed for use
by other research stations and farms.European Union
Structural Funding (EAGGF
Ubiquitous energy storage
This paper presents a vision of a future power system with "ubiquitous energy storage", where storage would be utilized at all levels of the electricity system. The growing requirement for storage is reviewed, driven by the expansion of distributed generation. The capabilities and existing applications of various storage technologies are presented, providing a useful review of the state of the art. Energy storage will have to be integrated with the power system and there are various ways in which this may be achieved. Some of these options are discussed, as are commercial and regulatory issues. In two case studies, the costs and benefits of some storage options are assessed. It is concluded that electrical storage is not cost effective but that thermal storage offers attractive opportunities
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Feasibility and initial efficacy of project-based treatment for people with ABI
Background: Communication impairments are common and pervasive for people a long time following acquired brain injury (ABI). These impairments have a significant impact on a person's quality of life (QOL) postâinjury. Projectâbased treatment is a treatment approach that could have an impact on communication skills and QOL for people with ABI a longâterm postâinjury. This treatment is embedded in a context of meaningful activities chosen by people with ABI, whereby, as a group, they work collaboratively to achieve a tangible end product.
Aims: To evaluate the feasibility and initial efficacy of projectâbased treatment on improving the communication skills and QOL for people with ABI.
Methods & Procedures: An exploratory controlled trial with alternate allocation of groups, and followâup at 6â8 weeks, was completed. Twentyâone people with chronic ABI were recruited in groups of two to three from community settings, allocated to either a TREATMENT (n = 11) or WAITLIST group (n = 10). Participants attended a 20âh groupâbased treatment over 6 weeks where they worked towards achieving a project that helped others. To determine feasibility, four criteria were used: demand, implementation, practicality and acceptability. A range of communication and QOL outcomes was used to determine a fifth feasibility criterion, initial efficacy. Some of these criteria were additionally used to evaluate the feasibility of the outcomes.
Outcomes & Results: All participants received the treatment as allocated with high attendance and no dropouts. The treatment was feasible to deliver as intended and was highly acceptable to participants. Medium and large effect sizes were found from preâ to postâtreatment, and from preâtreatment to followâup for measures of conversation, perceived communicative ability and QOL.
Conclusions & Implications: Projectâbased treatment is feasible with indications of initial efficacy for both communication skills and QOL. The treatment provides a promising new approach for improving communication skills and QOL in people with chronic acquired brain injuries in the community setting
Ecological PrinciplesâA Unifying Theme in Environmental Education
Using ecological principles to form the basis of a succinct list of general environmental education (EE) standards will bring unity and strength to EE. Environmental education literature supports the importance of understanding general ecological principles, and general ecological concepts are prevalent in both widely used and locally adapted EE programs. In addition, an understanding of general ecological principles is included in both NSES (National Science Education Standards) and NAAEE Guidelines for Excellence. This article presents an analysis of the frequency of ecological references in several EE programs and discusses the implications of general ecological principles as a common thread in EE
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