471 research outputs found
Finite temperature phase diagram of a spin-1 Bose gas
We formulate a self-consistent Hartree-Fock theory for a spin-1 Bose gas at
finite temperature and apply it to characterizing the phase diagram. We find
that spin coherence between thermal atoms in different magnetic sub-levels
develops via coherent collisions with the condensed atoms, and is a crucial
factor in determining the phase diagram. We develop analytical expressions to
characterize the interaction and temperature dependent shifts of the phase
boundaries.Comment: 11 pages, 5 figure
Entanglement of purification: from spin chains to holography
Purification is a powerful technique in quantum physics whereby a mixed
quantum state is extended to a pure state on a larger system. This process is
not unique, and in systems composed of many degrees of freedom, one natural
purification is the one with minimal entanglement. Here we study the entropy of
the minimally entangled purification, called the entanglement of purification,
in three model systems: an Ising spin chain, conformal field theories
holographically dual to Einstein gravity, and random stabilizer tensor
networks. We conjecture values for the entanglement of purification in all
these models, and we support our conjectures with a variety of numerical and
analytical results. We find that such minimally entangled purifications have a
number of applications, from enhancing entanglement-based tensor network
methods for describing mixed states to elucidating novel aspects of the
emergence of geometry from entanglement in the AdS/CFT correspondence.Comment: 40 pages, multiple figures. v2: references added, typos correcte
Antibacterial Effect of Eicosapentaenoic Acid against Bacillus cereus and Staphylococcus aureus: Killing Kinetics, Selection for Resistance, and Potential Cellular Target
Polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA; C20:5n-3), are attracting interest as possible new topical antibacterial agents, particularly due to their potency and perceived safety. However, relatively little is known of the underlying mechanism of antibacterial action of EPA or whether bacteria can develop resistance quickly against this or similar compounds. Therefore, the aim of this present study was to determine the mechanism of antibacterial action of EPA and investigate whether bacteria could develop reduced susceptibility to this fatty acid upon repeated exposure. Against two common Gram-positive human pathogens, Bacillus cereus and Staphylococcus aureus, EPA inhibited bacterial growth with a minimum inhibitory concentration of 64 mg/L, while minimum bactericidal concentrations were 64 mg/L and 128 mg/L for B. cereus and S. aureus, respectively. Both species were killed completely in EPA at 128 mg/L within 15 min at 37 °C, while reduced bacterial viability was associated with increased release of 260-nm-absorbing material from the bacterial cells. Taken together, these observations suggest that EPA likely kills B. cereus and S. aureus by disrupting the cell membrane, ultimately leading to cell lysis. Serial passage of the strains in the presence of sub-inhibitory concentrations of EPA did not lead to the emergence or selection of strains with reduced susceptibility to EPA during 13 passages. This present study provides data that may support the development of EPA and other fatty acids as antibacterial agents for cosmetic and pharmaceutical applications
Modeling and Analyzing Academic Researcher Behavior
. This paper suggests a theoretical framework for analyzing the mechanism of the behavior of academic researchers whose interests are tangled and vary widely in academic factors (the intrinsic satisfaction in conducting research, the improvement in individual research ability, etc.) or non-academic factors (career rewards, financial rewards, etc.). Furthermore, each researcher also has his/her different academic stances in their preferences about academic freedom and academic entrepreneurship. Understanding the behavior of academic researchers will contribute to nurture young researchers, to improve the standard of research and education as well as to boost collaboration in academia-industry. In particular, as open innovation is increasingly in need of the involvement of university researchers, to establish a successful approach to entice researchers into enterprises' research, companies must comprehend the behavior of university researchers who have multiple complex motivations. The paper explores academic researchers' behaviors through optimizing their utility functions, i.e. the satisfaction obtained by their research outputs. This paper characterizes these outputs as the results of researchers' 3C: Competence (the ability to implement the research), Commitment (the effort to do the research), and Contribution (finding meaning in the research). Most of the previous research utilized the empirical methods to study researcher's motivation. Without adopting economic theory into the analysis, the past literature could not offer a deeper understanding of researcher's behavior. Our contribution is important both conceptually and practically because it provides the first theoretical framework to study the mechanism of researcher's behavior
Effects of selective dilution on the magnetic properties of La_{0.7}Sr_{0.3}Mn_{1-x}M'_xO_3 (M' = Al, Ti)
The magnetic lattice of mixed-valence Mn ions in
LaSrMnO is selectively diluted by partial substitution of
Al or Ti for Mn. The ferromagnetic transition temperature and
the saturation magnetization both decrease with substitution. By
presenting the data in terms of selective dilution, in the
low-doping region is found to follow the relation
, where refers to
the undiluted system and is the dilution concentration defined
as or for Al or Ti,
respectively. The scaling behavior of can be
analyzed in the framework of the molecular-field theory and still valid when Mn
is substituted by both Al and Ti. The results are discussed with respect to the
contributions from ferromagnetic double exchange and other possible
antiferromagnetic superexchange interactions coexisting in the material.Comment: Revtex4, 4 pages, 4 figures, 2006 Halong Conference Repor
The fear of bad smell: Health risk awareness related to using waste in agricultural production in Vietnam
Waste watersWater reuseAgricultural productionFish farmingIrrigation waterPublic healthRisksSkin diseasesOrganic fertilizersWomen
Halliday\u27s Functional Grammar: Philosophical Foundation and Epistemology
It is difficult to track the philosophy foundation and epistemology of systemic functional grammar (SFG) formulated by Halliday in the 1980s as this kind of grammar views language as a systemic resource for meaning. Besides, it has had global impacts on linguistics and flourished in contemporary linguistic theory. Anyone who is familiar with Halliday\u27s work realizes that his SFG is an approach designed to analyze English texts. Halliday (1994: xv) explicitly states that “to construct a grammar for purposes of text analysis: one that would make it possible to say sensible and useful things about any text, spoken or written, in modern English.” The aim of this study is not about the applicability of SFG to text analysis as many researchers and scholars do. Our efforts are made to clarify the philosophical foundation of Halliday\u27s SFG. The paper presents on triangle: (i) language, mind and world; (ii) and empiricism in Halliday\u27s SFG
Selective dilution and magnetic properties of La_{0.7}Sr_{0.3}Mn_{1-x}M'_xO_3 (M' = Al, Ti)
The magnetic lattice of mixed-valence Mn ions in LaSrMnO
is selectively diluted by partial substitution of Mn by Al or Ti. The
ferromagnetic transition temperature and the saturation moment decreases with
substitution in both series. The volume fraction of the non-ferromagnetic
phases evolves non-linearly with the substitution concentration and faster than
theoretically expected. By presenting the data in terms of selective dilutions,
the reduction of is found to be scaled by the relative ionic
concentrations and is consistent with a prediction derived from molecular-field
theory.Comment: 6 pages, 5 figures, REVTex4.0. Submitted to PR
Local and global behaviour of nonlinear equations with natural growth terms
This paper concerns a study of the pointwise behaviour of positive solutions
to certain quasi-linear elliptic equations with natural growth terms, under
minimal regularity assumptions on the underlying coefficients. Our primary
results consist of optimal pointwise estimates for positive solutions of such
equations in terms of two local Wolff's potentials.Comment: In memory of Professor Nigel Kalto
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