Surmounting the sign problem in non-relativistic calculations: a case study with mass-imbalanced fermions

The calculation of the ground state and thermodynamics of mass-imbalanced Fermi systems is a challenging many-body problem. Even in one spatial dimension, analytic solutions are limited to special configurations and numerical progress with standard Monte Carlo approaches is hindered by the sign problem. The focus of the present work is on the further development of methods to study imbalanced systems in a fully non-perturbative fashion. We report our calculations of the ground-state energy of mass-imbalanced fermions using two different approaches which are also very popular in the context of the theory of the strong interaction (Quantum Chromodynamics, QCD): (a) the hybrid Monte Carlo algorithm with imaginary mass imbalance, followed by an analytic continuation to the real axis; and (b) the Complex Langevin algorithm. We cover a range of on-site interaction strengths that includes strongly attractive as well as strongly repulsive cases which we verify with non-perturbative renormalization group methods and perturbation theory. Our findings indicate that, for strong repulsive couplings, the energy starts to flatten out, implying interesting consequences for short-range and high-frequency correlation functions. Overall, our results clearly indicate that the Complex Langevin approach is very versatile and works very well for imbalanced Fermi gases with both attractive and repulsive interactions.Comment: 11 pages, 5 figure

The Distance to the Cygnus Loop from Hubble Space Telescope Imaging of the Primary Shock Front

We present a Hubble Space Telescope/WFPC2 narrow-band H-alpha image of a region on the northeastern limb of the Cygnus Loop supernova remnant. This location provides a detailed example of where the primary blast wave first encounters the surrounding interstellar medium. The filament structure is seen in exquisite detail in this image, which was obtained primarily as an EARLY ACQuisition image for a follow-up spectroscopic program. We compare the HST image to a digitized version of the POSS-I red plate to measure the proper motion of this filament. By combining this value for the proper motion with previous measurements of the shock velocity at this position we find that the distance to the Cygnus Loop is 440 (+130, -100) pc, considerably smaller than the canonical value of 770 pc. We briefly discuss the ramifications of this new distance estimate for our understanding of this prototypical supernova remnant.Comment: 18 pages, 3 Figures (2 JPEG and one Postscript

Identification of EOMES-expressing spermatogonial stem cells and their regulation by PLZF.

Long-term maintenance of spermatogenesis in mammals is supported by GDNF, an essential growth factor required for spermatogonial stem cell (SSC) self-renewal. Exploiting a transgenic GDNF overexpression model, which expands and normalizes the pool of undifferentiated spermatogonia between Plzf +/+ and Plzf lu/lu mice, we used RNAseq to identify a rare subpopulation of cells that express EOMES, a T-box transcription factor. Lineage tracing and busulfan challenge show that these are SSCs that contribute to steady state spermatogenesis as well as regeneration following chemical injury. EOMES+ SSCs have a lower proliferation index in wild-type than in Plzf lu/lu mice, suggesting that PLZF regulates their proliferative activity and that EOMES+ SSCs are lost through proliferative exhaustion in Plzf lu/lu mice. Single cell RNA sequencing of EOMES+ cells from Plzf +/+ and Plzf lu/lu mice support the conclusion that SSCs are hierarchical yet heterogeneous

The Effects of Foam Rolling and Static Stretching on Flexibility and Acute Muscle Soreness

Please view abstract in the attached PDF file

Experimental Testing and Modeling of 5 kW Oil-Free Open Drive Scroll Expander Using R245fa

Organic Rankine Cycles (ORC) are thermodynamic power cycles designed to generate work from low temperature sources, typically between 80 °C to 270 °C.  The low temperature heat input makes this technology attractive for applications in waste heat recovery from industrial processes, exhaust gas from diesel engines, solar systems, geothermal systems, and others.  The expander has the greatest effect on increasing the efficiency of an ORC. The operating  conditions that the expander is subjected to are directed related to its efficiency.  The performance of a 5 kW scroll expander with a displacement of 73.6 cm3 per revolution, operating at speeds from 500 to 3600 rpm, and using R245fa as the working fluid in a traditional Organic Ranking cycle is experimentally investigated In this paper. Tests were conducted varying the mass flow rate of the working fluid and varying source temperatures, while measuring the effective expander power production and the isentropic efficiency.  The experimental data was then used to develop a model of the scroll expander. Using this model, thermodynamic simulations were carried out for applications similar to exhaust gas waste heat recovery from internal combustion engines

The Perceptions of NSAID Use among One Midwestern DIII Athletic Department

NSAIDs are commonly used among athletes for a variety of reasons. The purpose of this research is to gain insight on Division III athletes’view and opinions of NSAIDs. A survey was developed incorporating the Theory of Planned Behavior and distributed to all winter and spring athletic teams of one Midwestern Dill University. By utilizing the Theory of Planned Behavior, this study found attitude toward behavior as the strongest predictor of behavioral intention (p \u3c .001), while both Perceived Behavioral control (p \u3c .001) and Intention (p \u3c .001) were statistically significant predictors of behavior. Another finding from the study was that athletes perceived less than 25% of their teammates as taking NSAIDs. Displaying the importance of an athlete s own personal values and opinions of NSAID use was the strongest predictor of intentions. Further assessment should include more athletes to get a better representation of the athletic department

The Burrell-Optical-Kepler-Survey (BOKS). I. Survey Description and Initial Results

We present the initial results of a 40 night contiguous ground-based campaign of time series photometric observations of a 1.39 deg^2 field located within the NASA Kepler Mission field of view. The goal of this pre-launch survey was to search for transiting extrasolar planets and to provide independent variability information of stellar sources. We have gathered a data set containing light curves of 54,687 stars from which we have created a statistical sub-sample of 13,786 stars between 14 < r < 18.5 and have statistically examined each light curve to test for variability. We present a summary of our preliminary photometric findings including the overall level and content of stellar variability in this portion of the Kepler field and give some examples of unusual variable stars found within. We present a preliminary catalog of 2,457 candidate variable stars, of which 776 show signs of periodicity. We also present three potential exoplanet candidates, all of which should be observable by the Kepler mission

Functional Redundancy of DICER Cofactors TARBP2 and PRKRA During Murine Embryogenesis Does Not Involve miRNA Biogenesis.

Several in vitro studies have suggested that canonical microRNA (miRNA) biogenesis requires the DICER cofactors TARBP2 and PRKRA for processing of pre-miRNAs to mature miRNAs. To investigate the roles of TARBP2 and PRKRA in miRNA biogenesis in vivo, and to determine possible functional redundancy, we first compared the phenotypes of Tarbp2 and Prkra single and double mutants. In contrast to Dicer -/- embryos, which die by embryonic day 7.5 (E7.5), single Tarbp2 -/- and Prkra -/- mice survive beyond E7.5 and either die perinatally or survive and exhibit cranial/facial abnormalities, respectively. In contrast, only a few Tarbp2 -/- ; Prkra -/- double mutants survived beyond E12.5, suggesting genetic redundancy between Tarbp2 and Prkra during embryonic development. Sequencing of miRNAs from single-mutant embryos at E15.5 revealed changes in abundance and isomiR type in Tarbp2 -/- , but not Prkra -/- , embryos, demonstrating that TARBP2, but not PRKRA, functions in miRNA biogenesis of a subclass of miRNAs, and suggesting that functional redundancy between TARBP2 and PRKRA does not involve miRNA biogenesis. Genetics 2018 Apr; 208(4):1513-22