6,585 research outputs found
Vlasov Description Of Dense Quark Matter
We discuss properties of quark matter at finite baryon densities and zero
temperature in a Vlasov approach. We use a screened interquark Richardson's
potential consistent with the indications of Lattice QCD calculations.
We analyze the choices of the quark masses and the parameters entering the
potential which reproduce the binding energy (B.E.) of infinite nuclear matter.
There is a transition from nuclear to quark matter at densities 5 times above
normal nuclear matter density. The transition could be revealed from the
determination of the position of the shifted meson masses in dense baryonic
matter. A scaling form of the meson masses in dense matter is given.Comment: 15 pages 4 figure
Microminiaturized, biopotential conditioning system (MBCS)
Multichannel, medical monitoring system allows almost complete freedom of movement for subject during monitoring periods. System comprises monitoring unit (biobelt), transmission line, and data acquisition unit. Belt, made of polybenzimidizole fabric, is wrapped around individual's waist and held in place by overlapping sections of Velcro closure material
Zone Determinant Expansions for Nuclear Lattice Simulations
We introduce a new approximation to nucleon matrix determinants that is
physically motivated by chiral effective theory. The method involves breaking
the lattice into spatial zones and expanding the determinant in powers of the
boundary hopping parameter.Comment: 20 pages, 6 figures, revtex4 (version to appear in PRC
Truncated-Determinant Diagrammatic Monte Carlo for Fermions with Contact Interaction
For some models of interacting fermions the known solution to the notorious
sign-problem in Monte Carlo (MC) simulations is to work with macroscopic
fermionic determinants; the price, however, is a macroscopic scaling of the
numerical effort spent on elementary local updates. We find that the {\it
ratio} of two macroscopic determinants can be found with any desired accuracy
by considering truncated (local in space and time) matices. In this respect, MC
for interacting fermionic systems becomes similar to that for the
sign-problem-free bosonic systems with system-size independent update cost. We
demonstrate the utility of the truncated-determinant method by simulating the
attractive Hubbard model within the MC scheme based on partially summed Feynman
diagrams. We conjecture that similar approach may be useful in other
implementations of the sign-free determinant schemes.Comment: results of the actual Hubbard model simulations are adde
Bismuth ferrite enhanced ZnO solid state dye-sensitised solar cell
ZnO dye sensitized solar cells have been reported to be plagued with issues of dye aggregation which increased current recombination. This dye aggregation has been linked to the pH 5 ruthenium-based dye solutions, which is below ZnO's point of zero charge of pH 9, resulting in positive surface charges on ZnO which form Zn2+ - dye complexes. In this paper, a heterogeneous architecture of ZnO and bismuth ferrite (BiFeO3 or BFO) is synthesized using a technique which allows the synthesis using purely chemical solution techniques. BFO is a perovskite studied extensively for its multiferroic properties and its potential for anomalous photovoltages. The solid state solar cells are sensitized with N719, and uses copper thiocyanate (CuSCN) as a hole conductor. The ZnO-BFO-N719-CuSCN heterogeneous architecture solar cell showed efficiencies which increased ca four-fold to 0.38% and Jsc which doubled to 1.38 mA/cm2 compared to ZnO-N719-CuSCN architectures. We will report that the addition of BFO improved performances due to the reduction of dye aggregation due to BFO's pzc of pH 6.5 which is close to the pH 5 of the dye solution, as well as BFO's role as an electron blocking layer which prevents the back tunneling of electrons from ZnO to CuSCN
Coulomb blockade and quantum tunnelling in the low-conductivity phase of granular metals
We study the effects of Coulomb interaction and inter-grain quantum
tunnelling in an array of metallic grains using the phase-functional approach
for temperatures well below the charging energy of individual
grains yet large compared to the level spacing in the grains. When the
inter-grain tunnelling conductance , the conductivity in
dimensions decreases logarithmically with temperature
(), while for ,
the conductivity shows simple activated behaviour ().
We show, for bare tunnelling conductance , that the parameter
determines the competition between
charging and tunnelling effects. At low enough temperatures in the regime
, a charge is shared among a finite
number of grains, and we find a soft
activation behaviour of the conductivity, , where is the effective
coordination number of a grain.Comment: 11 pages REVTeX, 3 Figures. Appendix added, replaced with published
versio
Bioaccessibility of Carotenoids and Tocopherols in Marine Microalgae, Nannochloropsis sp. and Chaetoceros sp.
Microalgae can produce various natural products such as pigments, enzymes, unique
fatty acids and vitamin that benefit humans. The objective of the study is to study the
bioaccessibility of carotenoids (β-carotene and lycopene) and vitamin E (α- and β-
tocopherol) of Nannochloropsis oculata and Chaetoceros calcitrans. Analyses were carried
out for both the powdered forms of N. oculata and C. calcitrans, and the dried extract
forms of N. oculata and C. calcitrans. In vitro digestion method together with RP-HPLC
was used to determine the bioaccessibility of carotenoids and vitamin E for both forms
of microalgae. Powdered form of N. oculata had the highest bioaccessibility of β-carotene
(28.0 ± 0.6 g kg-1), followed by dried extract N. oculata (21.5 ± 1.1 g kg-1), dried extract C.
calcitrans (16.9 ± 0.1 g kg-1), and powdered C. calcitrans (15.6 ± 0.1 g kg-1). For lycopene,
dried extract of N. oculata had the highest bioaccessibility of lycopene (42.6 ± 1.1 g kg-
1), followed by dried extract C. calcitrans (41.9 ± 0.6 g kg-1), powdered C. calcitrans (39.7
± 0.1 g kg-1) and powdered N. oculata (32.6 ± 0.7 g kg-1). Dried extract C. calcitrans had the
highest bioaccessibility of α-tocopherol (72.1 ± 1.2 g kg-1). However, β-tocopherol was
not detected in both dried extract and powdered form of C. calcitrans. In conclusion, all
samples in their dried extract forms were found to have significantly higher
bioaccessibilities than their powdered forms. This may be due to the disruption of the
food matrix contributing to a higher bioaccessibility of nutrients shown by the dried
extract form
Intranasal immunisation with Ag85B peptide 25 displayed on Lactococcus lactis using the PilVax platform induces antigen-specific B- and T-cell responses.
Mycobacterium tuberculosis (Mtb) remains a global epidemic despite the widespread use of BCG. Consequently, novel vaccines are required to facilitate a reduction in Mtb morbidity and mortality. PilVax is a peptide delivery strategy for the generation of highly specific mucosal immune responses and is based on the food-grade bacterium Lactococcus lactis that is used to express selected peptides engineered within the Streptococcus pyogenes M1T1 pilus, allowing for peptide amplification, stabilisation, and enhanced immunogenicity. In the present study, the dominant T cell epitope from the Mtb protein Ag85B was genetically engineered into the pilus backbone subunit and expressed on the surface of L. lactis. Western blot and flow cytometry confirmed formation of pilus containing the peptide DNA sequence. B cell responses in intranasally vaccinated mice were analysed by ELISA while T cell responses were analysed by flow cytometry. Serum titres of peptide specific IgG and IgA were detected, confirming vaccination produced antibodies against the cognate peptide. Peptide-specific IgA was also detected across several mucosal sites sampled. Peptide-specific CD4+ T cells were detected at levels similar to those of mice immunised with BCG. PilVax immunisation resulted in an unexpected increase in the numbers of CD3+ CD4- CD8- (double negative, DN) T cells in the lungs of vaccinated mice. Analysis of cytokine production following stimulation with the cognate peptide showed the major cytokine producing cells to be CD4+ T cells and DN T cells. This study provides insight into the antibody and peptide specific cellular immune responses generated by PilVax vaccination and demonstrates the suitability of this vaccine for conducting a protection study
Positioning Control of an Antagonistic Pneumatic Muscle Actuated System using Feedforward Compensation with Cascaded Control Scheme
This paper presents a feedforward compensation with cascaded control scheme (FFC) for the positioning control of a vertical antagonistic based pneumatic muscle actuated (PMA) system. Owing to the inherent nonlinearities and time varying parameters exhibited by PMA, conventional fixed controllers unable to demonstrate high positioning performance. Hence, the feedforward compensation with cascaded control scheme is proposed whereby the scheme includes a PID controller coupled with nonlinear control elements. The proposed scheme has a simple control structure in addition to its straightforward design procedures. Though there are nonlinear control elements involved, these elements are derived from the open loop system responses that does not requires any accurate known parameters. Performance of the FFC scheme are then evaluated experimentally and compared to a PID controller with feedforward compensation (FF-PID) in point-to-point motion of different step heights. Overall, the experimental results show that the effectiveness of the proposed FFC scheme in reducing the steady state error to zero in comparison to FF-PID controller for all cases of step heights examined
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