1,035 research outputs found
QCD with dynamical Wilson fermions at
We study QCD with two flavors of dynamical Wilson fermions at
and three values of . The corresponding pion masses are 0.375, 0.324
and 0.262 in lattice units, with pion to rho mass ratios of 0.76, 0.71 and
0.62, respectively. We use the configurations to compute the heavy quark
potential, leading to lattice spacings of 0.110, 0.105 and 0.099 fm, and to
compute spectroscopy for several different valence quark 's.Comment: LaTex 4 pages, 4 figures. Talk presented at LATTICE96(spectrum
The Weakly Coupled Gross-Neveu Model with Wilson Fermions
The nature of the phase transition in the lattice Gross-Neveu model with
Wilson fermions is investigated using a new analytical technique. This involves
a new type of weak coupling expansion which focuses on the partition function
zeroes of the model. Its application to the single flavour Gross-Neveu model
yields a phase diagram whose structure is consistent with that predicted from a
saddle point approach. The existence of an Aoki phase is confirmed and its
width in the weakly coupled region is determined. Parity, rather than chiral
symmetry breaking naturally emerges as the driving mechanism for the phase
transition.Comment: 15 pages including 1 figur
Implementation of Bioenergy Systems towards Achieving United Nationsâ Sustainable Development Goals in Rural Bangladesh
This research presents a conceptual model to illustrate how people living in rural areas can
harness bioenergy to create beneficial âcommunity-drivenâ income-generating activities. The research
is contextualised within the rural developing areas of Bangladesh where people live in abject poverty
and energy deficiency. The research methodology applied in this study aims to determine the basic
requirements for implementing community-based anaerobic digestion (AD) facilities and illustrate
how an AD facility positively impacts upon the lives of rural communities directly after its installation.
The survey results demonstrate that implementing a biogas plant can save 1 h and 43 min of worktime
per day for a rural family where women are generally expected to for cook (by the long-term
tradition). In addition to the positive impacts on health and climate change through adoption of
clean energy generation, this time saving could be utilised to improve women0s and childrenâs
education. The research concludes that, by providing easy access to clean bioenergy, AD can change
peopleâs quality of life, yielding major social, economic and environmental transformations; key
benefits include: extending the working day; empowering women; reducing indoor air pollution;
and improving peopleâs health and welfare. Each of these tangible benefits can positively contribute
towards achievement of the UNâs Sustainable Development Goals. This work demonstrates the
potential to increase the implementation of AD systems in other developing world countries that
have similar geographic and socioeconomic conditions
Fermion-scalar interactions with domain wall fermions
Domain wall fermions are defined on a lattice with an extra direction the
size of which controls the chiral properties of the theory. When gauge fields
are coupled to domain wall fermions the extra direction is treated as an
internal flavor space. Here it is found that this is not the case for scalar
fields. Instead, the interaction takes place only along the link that connects
the boundaries of the extra direction. This reveals a richness in the way
different spin particles are coupled to domain wall fermions. As an
application, 4-Fermi models are studied using large N techniques and the
results are supported by numerical simulations with N=2. It is found that the
chiral properties of domain wall fermions in these models are good across a
large range of couplings and that a phase with parity-flavor broken symmetry
can develop for negative bare masses if the number of sites along the extra
direction is finite.Comment: LaTeX, 17 pages, 8 eps figures; comment regarding the width of Aoki
phase added in sec. 3; references adde
A numerical reinvestigation of the Aoki phase with N_f=2 Wilson fermions at zero temperature
We report on a numerical reinvestigation of the Aoki phase in lattice QCD
with two flavors of Wilson fermions where the parity-flavor symmetry is
spontaneously broken. For this purpose an explicitly symmetry-breaking source
term was added to the fermion action.
The order parameter was computed with
the Hybrid Monte Carlo algorithm at several values of on
lattices of sizes to and extrapolated to . The existence of a
parity-flavor breaking phase can be confirmed at and 4.3, while we
do not find parity-flavor breaking at and 5.0.Comment: 8 pages, 5 figures, Revised version as to be published in Phys.Rev.
Determination of the Potential Impact of Domestic Anaerobic Digester Systems: A Community Based Research Initiative in Rural Bangladesh
This research examines the potential impact of domestic anaerobic digester (AD) systems adopted in Bangladesh and similar developing countries. Cattle dung and poultry litter feed stocks were specifically investigated, because these were freely available and plentiful to people living within agricultural areas of rural Bangladesh. Data was collected to ascertain whether these two representative AD facility types provide tangible social, economic and environmental impact that benefits homeowners. Primary quantitative and qualitative data was obtained by field data collection, and meeting with expert groups and stakeholders. Empirical analysis conducted revealed that variations were found in the biomass feedstocks available on different sites but also differences were apparent in terms of the operations and maintenance (O and M) systems of the biogas plants operated. The biogas and methane yield variation was also measured, and variations were found in the cattle dung and poultry litter AD yield capacity. Overall, 64% of feedstock was utilised, 91% of biogas plants remain underfed and energy yield efficiency was 57% from cattle smallholdingsâ AD and 28% from poultry farmsâ AD. These results showed that small scale AD can offer a significant impact upon rural lifestyles through augmented economics, improved social activities, relationship building with neighbours and improved lifestyle achieved via time savings accrued. These results could help rural entrepreneurs, AD equipment providers and government institutions to develop a road map to implement future AD installation on a much wider geographical scale
Limited contributions of plant pathogens to densityâdependent seedling mortality of mast fruiting Bornean trees
Fungal pathogens are implicated in driving tropical plant diversity by facilitating strong, negative densityâdependent mortality of conspecific seedlings (CâNDD). Assessment of the role of fungal pathogens in mediating coexistence derives from relatively few tree species and predominantly the Neotropics, limiting our understanding of their role in maintaining hyperâdiversity in many tropical forests. A key question is whether fungal pathogenâmediated CâNDD seedling mortality is ubiquitous across diverse plant communities. Using a manipulative shadehouse experiment, we tested the role of fungal pathogens in mediating CâNDD seedling mortality of eight mast fruiting Bornean trees, typical of the speciesârich forests of South East Asia. We demonstrate speciesâspecific responses of seedlings to fungicide and density treatments, generating weak negative densityâdependent mortality. Overall seedling mortality was low and likely insufficient to promote overall community diversity. Although conducted in the same way as previous studies, we find little evidence that fungal pathogens play a substantial role in determining patterns of seedling mortality in a SE Asian mast fruiting forest, questioning our understanding of how JanzenâConnell mechanisms structure the plant communities of this globally important forest type
Diploptene ÎŽ13C values from contemporary thermokarst lake sediments show complex spatial variation
Cryospheric changes in northern high latitudes are linked to significant greenhouse gas flux to the atmosphere, for example, methane that originates from organic matter decomposition in thermokarst lakes. The set of pathways that link methane production in sediments, via oxidation in the lake system, to the flux of residual methane to the atmosphere is complex and exhibits temporal and spatial variation. The isotopic signal of bacterial biomarkers (hopanoids, e.g. diploptene) in sediments has been used to identify contemporary ocean-floor methane seeps and, in the geological record, periods of enhanced methane production (e.g. the PETM). The biomarker approach could potentially be used to assess temporal changes in lake emissions through the Holocene via the sedimentary biomarker record. However, there are no data on the consistency of the signal of isotopic depletion in relation to source or on the amount of noise (unexplained variation) in biomarker values from modern lake sediments. We assessed methane oxidation as represented by the isotopic signal of biomarkers from methane oxidising bacteria (MOB) in multiple surface sediment samples in three distinct areas known to emit varying levels of methane in two shallow Alaskan thermokarst lakes. Diploptene was present and had ÎŽ13C values lower than -38gâ° in all sediments analysed, suggesting methane oxidation was widespread. However, there was considerable variation in ÎŽ13C values within each area. The most 13C-depleted diploptene was found in an area of high methane ebullition in Ace Lake (diploptene ÎŽ13C values between -68.2 and -50.1â°). In contrast, significantly higher diploptene ÎŽ13C values (between -42.9 and -38.8gâ°) were found in an area of methane ebullition in Smith Lake. ÎŽ13C values of diploptene between -56.8 and -46.9gâ° were found in the centre of Smith Lake, where ebullition rates are low but diffusive methane efflux occurs. The small-scale heterogeneity of the samples may reflect patchy distribution of substrate and/or MOB within the sediments. The two ebullition areas differ in age and type of organic carbon substrate, which may affect methane production, transport, and subsequent oxidation. Given the high amount of variation in surface samples, a more extensive calibration of modern sediment properties, within and among lakes, is required before down-core records of hopanoid isotopic signatures are developed. © Author(s) 2016
Boson induced s-wave pairing in dilute boson-fermion mixtures
We show that in dilute boson-fermion mixtures with fermions in two internal
states, even when the bare fermion-fermion interaction is repulsive, the
exchange of density fluctuations of the Bose condensate may lead to an
effective fermion-fermion attraction, and thus to a Cooper instability in the
s-wave channel. We give an analytical method to derive the associated in
the limit where the phonon branch of the Bogoliubov excitation spectrum of the
bosons is important. We find a of the same order as for a pure Fermi gas
with bare attraction.Comment: 12 pages, no figure
Introduction of new vaccines for immunization in pregnancy - Programmatic, regulatory, safety and ethical considerations
Immunizing pregnant women is a promising strategy to reduce infectious disease-related morbidity and
mortality in pregnant women and their infants. Important pre-requisites for the successful introduction
of new vaccines for immunization in pregnancy include political commitment and adequate financial
resources: trained, committed and sufficient numbers of healthcare workers to deliver the vaccines; close
integration of immunization programs with antenatal care and Maternal and Child Health services; adequate access to antenatal care by pregnant women in the country (especially in low and middle-income
countries (LMIC)); and a high proportion of births occurring in health facilities (to ensure maternal and
neonatal follow-up can be done). The framework needed to advance a vaccine program from product
licensure to successful country-level implementation includes establishing and organizing evidence for
anticipated vaccine program impact, developing supportive policies, and translating policies into local
action. International and national coordination efforts, proactive planning from conception to implementation of the programs (including country-level policy making, planning, and implementation, regulatory
guidance, pharmacovigilance) and country-specific and cultural factors must be taken into account during the vaccines introduction
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