Lattice theory for nonrelativistic fermions in one spatial dimension

I derive a loop representation for the canonical and grand-canonical partition functions for an interacting four-component Fermi gas in one spatial dimension and an arbitrary external potential. The representation is free of the "sign problem" irrespective of population imbalance, mass imbalance, and to a degree, sign of the interaction strength. This property is in sharp contrast with the analogous three-dimensional two-component interacting Fermi gas, which exhibits a sign problem in the case of unequal masses, chemical potentials, and repulsive interactions. The one-dimensional system is believed to exhibit many phenomena in common with its three-dimensional counterpart, including an analog of the BCS-BEC crossover, and nonperturbative universal few- and many-body physics at scattering lengths much larger than the range of interaction, making the theory an interesting candidate for numerical study. Positivity of the probability measure for the partition function allows for a mean-field treatment of the model; here, I present such an analysis for the interacting Fermi gas in the SU(4) (unpolarized, mass-symmetric) limit, and demonstrate that there exists a phase in which a continuum limit may be defined.Comment: 12 pages, 6 figures, references adde

Cysteine-10 on 17 β-Hydroxysteroid dehydrogenase 1 has stabilizing interactions in the cofactor binding region and renders sensitivity to sulfhydryl modifying chemicals

17 β-Hydroxysteroid dehydrogenase type 1 (17 β -HSD1) catalyzes the conversion of estrone to the potent estrogen estradiol. 17 β -HSD1 is highly expressed in breast and ovary tissues and represents a prognostic marker for the tumor progression and survival of patients with breast cancer and other estrogen-dependent tumors. Therefore, the enzyme is considered a promising drug target against estrogen-dependent cancers. For the development of novel inhibitors, an improved understanding of the structure-function relationships is essential. In the present study, we examined the role of a cysteine residue, Cys(10), in the Rossmann-fold NADPH binding region, for 17 β -HSD1 function and tested the sensitivity towards sulfhydryl modifying chemicals. 3D structure modeling revealed important interactions of Cys(10) with residues involved in the stabilization of amino acids of the NADPH binding pocket. Analysis of enzyme activity revealed that 17 β -HSD1 was irreversibly inhibited by the sulfhydryl modifying agents N-ethylmaleimide (NEM) and dithiocarbamates. Preincubation with increasing concentrations of NADPH protected 17 β -HSD1 from inhibition by these chemicals. Cys(10)Ser mutant 17 β -HSD1 was partially protected from inhibition by NEM and dithiocarbamates, emphasizing the importance of Cys(10) in the cofactor binding region. Substitution of Cys(10) with serine resulted in a decreased protein half-life, without significantly altering kinetic properties. Despite the fact that Cys(10) on 17 β -HSD1 seems to have limited potential as a target for new enzyme inhibitors, the present study provides new insight into the structure-function relationships of this enzyme

Assessing housing quality and its impact on health, safety and sustainability

Background The adverse health and environmental effects of poor housing quality are well established. A central requirement for evidence-based policies and programmes to improve housing standards is a valid, reliable and practical way of measuring housing quality that is supported by policy agencies, the housing sector, researchers and the public. Methods This paper provides guidance on the development of housing quality-assessment tools that link practical measures of housing conditions to their effects on health, safety and sustainability, with particular reference to tools developed in New Zealand and England. Results The authors describe how information on housing quality can support individuals, agencies and the private sector to make worthwhile improvements to the health, safety and sustainability of housing. The information gathered and the resultant tools developed should be guided by the multiple purposes and end users of this information. Other important issues outlined include deciding on the scope, detailed content, practical administration issues and how the information will be analysed and summarised for its intended end users. There are likely to be considerable benefits from increased international collaboration and standardisation of approaches to measuring housing hazards. At the same time, these assessment approaches need to consider local factors such as climate, geography, culture, predominating building practices, important housing-related health issues and existing building codes. Conclusions An effective housing quality-assessment tool has a central role in supporting improvements to housing. The issues discussed in this paper are designed to motivate and assist the development of such tools

Time Management Amongst Small Business Owner/Managers: An Analysis of Retail Pharmacies in Western Australia

The usage of time by small business owner/managers is a relatively poorly understood phenomenon. Whilst several studies have previously attempted to measure how much time owners spend working on their business, few researchers have tried to evaluate what activities and tasks consume that time. This is an important issue for small firms, because time is a limited resource and its use needs to be maximised if an owner is to achieve all the goals set for his or her business.A study of 155 retail ("community") pharmacy owner/managers throughout Western Australia sought to measure what proportion of their time was spent on each of six different management responsibilities: marketing; client relations; dealing with external stakeholders; record-keeping & paperwork; business planning and strategy; and other issues (such as staffing matters or technology issues). The study also sought to evaluate what, if any, links existed between the owner's age, their gender, firm size and the variations in the pattern of time usage.It was found that no clear links could be established between time consumption and any of the above three variables. However, three distinctively different types of managerial time styles were identified "shop floor" owner/managers (who are focused on customer contact and relationships), "proactive" managers (who focus on business development, marketing and strategic planning), and "duty bound" proprietors (who concentrate on administrative tasks)

Hexose-6-phosphate dehydrogenase modulates the effect of inhibitors and alternative substrates of 11[beta]-hydroxysteroid dehydrogenase 1

Intracellular glucocorticoid reactivation is catalyzed by 11[beta]-hydroxysteroid dehydrogenase 1 (11[beta]-HSD1), which functions predominantly as a reductase in cells expressing hexose-6-phosphate dehydrogenase (H6PDH). We recently showed that the ratios of cortisone to cortisol and 7-keto- to 7-hydroxy-neurosteroids are regulated by 11[beta]-HSD1 and very much depend on co-expression with H6PDH, providing cosubstrate NADPH. Here, we investigated the impact of H6PDH on the modulation of 11[beta]-HSD1-dependent inter-conversion of cortisone and cortisol by inhibitors and alternative substrates. Using HEK-293 cells expressing 11[beta]-HSD1 or co-expressing 11[beta]-HSD1 and H6PDH, we observed significant differences of 11[beta]-HSD1 inhibition by natural and pharmaceutical compounds as well as endogenous hormone metabolites. Furthermore, we show potent and dose-dependent inhibition of 11[beta]-HSD1 by 7-keto-DHEA in differentiated human THP-1 macrophages and in HEK-293 cells over-expressing 11[beta]-HSD1 with or without H6PDH. In contrast, 7-ketocholesterol (7-KC) did not inhibit 11[beta]-HSD1 in HEK-293 cells, even in the presence of H6PDH, but inhibited 11[beta]-HSD1 reductase activity in differentiated THP-1 macrophages (IC~50~ = 8.1 +/- 0.9 [mu]M). 7-keto-DHEA but not 7-KC inhibited 11[beta]-HSD1 in HEK-293 cell lysates. In conclusion, cellular factors such as H6PDH can significantly modulate the effect of inhibitors and alternative 7-oxygenated substrates on intracellular glucocorticoid availability

Foreign National Doctoral Students In U.S. Economics Programs

This paper examines why enrollment of foreign national students in U.S. economics graduate programs increased so dramatically since the 1960s.   New information regarding the “stay rates” of foreign national students is examined.  The paper concludes that growth in the number of  foreign national economics graduate students was related to the quality of U.S. graduate programs, growth in foreign social science baccalaureate degree awards, growing foreign incomes, and movement of foreign economies towards markets.  These trends were especially pronounced in Asia, where most foreign national economics students are from

Lattice Monte Carlo calculations for unitary fermions in a finite box

We perform lattice Monte Carlo simulations for up to 66 unitary fermions in a finite box using a highly improved lattice action for nonrelativistic spin 1/2 fermions. We obtain a value of $0.366^{+0.016}_{-0.011}$ for the Bertsch parameter, defined as the energy of the unitary Fermi gas measured in units of the free gas energy in the thermodynamic limit. In addition, for up to four unitary fermions, we compute the spectrum of the lattice theory by exact diagonalization of the transfer matrix projected onto irreducible representations of the octahedral group for small to moderate size lattices, providing an independent check of our few-body simulation results. We compare our exact numerical and simulation results for the spectrum to benchmark studies of other research groups, as well as perform an extended analysis of our lattice action improvement scheme, including an analysis of the errors associated with higher partial waves and finite temporal discretization.Comment: Significant revisions from previous version. Included data at a larger volume and performed an infinite volume extrapolation of the Bertsch parameter. Published versio

On a generalization of Jacobi's elliptic functions and the Double Sine-Gordon kink chain

A generalization of Jacobi's elliptic functions is introduced as inversions of hyperelliptic integrals. We discuss the special properties of these functions, present addition theorems and give a list of indefinite integrals. As a physical application we show that periodic kink solutions (kink chains) of the double sine-Gordon model can be described in a canonical form in terms of generalized Jacobi functions.Comment: 18 pages, 9 figures, 3 table

Fluorescent ligand for human progesterone receptor imaging in live cells.

We employed molecular modeling to design and then synthesize fluorescent ligands for the human progesterone receptor. Boron dipyrromethene (BODIPY) or tetramethylrhodamine were conjugated to the progesterone receptor antagonist RU486 (Mifepristone) through an extended hydrophilic linker. The fluorescent ligands demonstrated comparable bioactivity to the parent antagonist in live cells and triggered nuclear translocation of the receptor in a specific manner. The BODIPY labeled ligand was applied to investigate the dependency of progesterone receptor nuclear translocation on partner proteins and to show that functional heat shock protein 90 but not immunophilin FKBP52 activity is essential. A tissue distribution study indicated that the fluorescent ligand preferentially accumulates in tissues that express high levels of the receptor in vivo. The design and properties of the BODIPY-labeled RU486 make it a potential candidate for in vivo imaging of PR by positron emission tomography through incorporation of (18)F into the BODIPY core