d_{xy}-Density wave in fermion-fermion cold atom mixtures

We study density wave instabilities in a doubly-degenerate Fermi-Fermi mixture with $SU(2)\times SU(2)$ symmetry on a square lattice. For sufficiently large on-site inter-species repulsion, when the two species of fermions are both at half-filling, two conventional ($s$-wave) number density waves are formed with a $\pi$-phase difference between them to minimize the inter-species repulsion. Upon moving one species away from half-filling, an unconventional density wave with $d_{xy}$-wave symmetry emerges. When both species are away from the vicinity of half-filling, superconducting instabilities dominate. We present results of a functional renormalization-group calculation that maps out the phase diagram at weak couplings. Also, we provide a simple explanation for the emergence of the $d_{xy}$-density wave phase based on a four-patch model. We find a robust and general mechanism for $d_{xy}$-density-wave formation that is related to the shape and size of the Fermi surfaces. The density imbalance between the two species of fermions in the vicinity of half-filling leads to phase-space discrepancy for different inter-species Umklapp couplings. Using a phase space argument for leading corrections in the one-loop renormalization group approach to fermions, we show that the phase-space discrepancy in our system causes opposite flows for the two leading intra-species Umklapp couplings and that this triggers the $d_{xy}$-density-wave instability.Comment: revised long version; 8 pages, 7 figure

Classical Extended Conformal Algebras Associated with Constrained KP Hierarchy

We examine the conformal property of the second Hamiltonian structure of constrained KP hierarchy derived by Oevel and Strampp. We find that it naturallygives a family of nonlocal extended conformal algebras. We give two examples of such algebras and find that they are similar to Bilal's V algebra. By taking a gauge transformation one can map the constrained KP hierarchy to Kuperschmidt's nonstandard Lax hierarchy. We consider the second Hamiltonian structure in this representation. We show that after mapping the Lax operator to a pure differential operator the second structure becomes the sum of the second and the third Gelfand-Dickey brackets defined by this differential operator. We show that this Hamiltonian structure defines the W-U(1)-Kac-Moody algebra by working out its conformally covariant form.Comment: NHCU-HEP-94-28, 19 pages (Plain TeX

BIOMECHANICAL ANALYSIS OF THE SNATCH TECHNIQUE OF ELITE MALES IN TAIWAN

The study compared two-dimensional snatch parameters of Taiwan elite males with International athletes by two-dimensional snatch parameters. Two males who were good Weight Lifting athletes in Taiwan were analyzed through PEAK motion analysis system to obtain kinematic data of the bar bell and human body. The result we found out as follows (1) The maximum velocity of barbell raising of this study was from 2.049 m/s to 2.124 m/so (2) The barbell speed ratio of the first and second pull of male lifters of this study was from 1.07 to 1.47. (3) The percentage of barbell height to the lifters' height of females lifters was 73% to 74% (4) The vertical dropping velocity of gravity of body of this study was 203.1 m/s to 205.7 m/s

An Exploration of Sedentary Behavior, Physical Activity, and Quality of Life During the COVID-19 Outbreak

Objectives: Staying physically active is a cost-efficient strategy for disease prevention during a pandemic. The purposes of this study were to explore precautionary behaviors, psychological factors associated with physical activity and sedentary behavior, and impacts of active and sedentary lifestyles on the quality of life in the early stage of the coronavirus disease 2019 (COVID-19) outbreak.Methods: Participants were community-dwelling adults aged over 20 years who had not been infected with COVID-19 and who lived in the United States. A study with a cross-sectional design was conducted between July and October 2020. Quantitative data were collected by a self-reported questionnaire.Results: In total, 467 valid responses were obtained. Participants who engaged in an active lifestyle had significantly higher scores on all domains of quality of life compared to those who engaged in an inactive lifestyle. Participants with a non-sedentary lifestyle had significantly higher scores of psychological and social domains of quality of life than those with a sedentary lifestyle.Conclusion: Engaging in an active lifestyle and avoiding a sedentary lifestyle are recommended when facing future, unpredictable pandemics similar to COVID-19

RELATIONSHIP BETWEEN OVER-ARM THROWING PATTERN AND THROWING PERFORMANCE

Throwing is a common movement among the upper extremities activities. This study examined the relationship between throwing patterns and throwing distance. Eighty-five age 21 years old students (m =29, F =56)voluntarily participated in the study. Each subject threw a tennis ball as hard as they could straightforward for three trials. A video camera at subjects' right hand side was used to record the subjects' motion. The Burton's (1992) amendment of DSOT table was used to quantify the throwing patterns. Data collected was examined by Pearson correlation(p < .05). The results were as follows: 1. the trunk rotation was found to associated with throwing distance for the male SUbject, 2. the backswing and trunk rotation were associated with throwing distance for the female SUbject