Quark Mass Ratios in ChPT with the Difference of Quark Condensates Considered

The chiral effective Lagrangian for pseudoscalar nonet is constructed in consideration of isospin breaking. And the difference of quark condensates is taken accounted. The SU(3) singlet eta0 is not taken as Goldstone-boson. The mixing with and without isospin symmetry is considered. The quark mass ratios are obtained through solving the mass equations of mesons. We estimate the change of quark mass ratios according to the change of the masses of pion+ and kaon+ to see how the electromagnetic corrections affect our results. It turn out that massless up quark is possible. The upper limit for mu/md is around 0.39. 2ms/(mu+md)=24.23~25.12. The values for quark condensate ratios and other constants are limited in narrow ranges.Comment: 10 page

Role of Particle Interactions in the Feshbach Conversion of Fermion Atoms to Bosonic Molecules

We investigate the Feshbach conversion of fermion atomic pairs to condensed boson molecules with a microscopic model that accounts the repulsive interactions among all the particles involved. We find that the conversion efficiency is enhanced by the interaction between boson molecules while suppressed by the interactions between fermion atoms and between atom and molecule. In certain cases, the combined effect of these interactions leads to a ceiling of less than 100% on the conversion efficiency even in the adiabatic limit. Our model predicts a non-monotonic dependence of the efficiency on mean atomic density. Our theory agrees well with recent experiments on $^6$Li and $^{40}$K.Comment: 5 pages, 4 figure

A causational analysis of scholars' years of active academic careers vis-à-vis their academic productivity and academic influence

Taking the scholarly activities of 73 doctoral program mentors working at the Chinese Academy of Medical Sciences &amp; Peking Union Medical College (the CAMS &amp; PUMC) as a sample of our investigative survey, we tried using such statistical methods as the analysis of variance (ANOVA), factor analysis and correlation analysis to compare the different characteristics of scholarship assessment of Chinese medical scholars as exhibited in their published papers in domestic and foreign journals. Our research findings show that citations per paper and A-index are more suitable for assessing the highly accomplished senior Chinese medical professionals (e.g. academicians) for their domestic and international scholarship attainment. In contrast, the m-quotient is not deemed appropriate to assess their academic influence both at home and abroad. Upon our further analysis of 6 evaluative indicators, we noticed that these indicators might be applied in two different aspects: One is from the viewpoint of Chinese scholars' academic influence at home, which has been evaluated mainly from the perspective of &quot;total&quot; amount and &quot;average&quot; amount of both publications and citations. The other is from their academic impact embodied by the means of documents retrieved from the Web of Science, which is mainly assessed from the two viewpoints of publications and citations. It is suggested that the accumulated time-length of a given scholar's active engagement in professional practice in a specific subject area be taken into consideration while assessing a researcher's performance at home and abroad</p

2-Amino-4,6-dimethyl­pyrimidine–benzoic acid (1/1)

The crystal of the title compound, C6H9N3·C7H6O2, contains tetra­meric hydrogen-bonded units comprising a central pair of 2-amino­pyrimidine mol­ecules linked across a centre of inversion by N—H⋯N hydrogen bonds and two pendant benzoic acid mol­ecules attached through N—H⋯O and O—H⋯N hydrogen bonds. These hydrogen-bonded units are arranged into layers in (002)

Quasinormal modes for asymptotic safe black holes

Under the hypothesis of asymptotic safety of gravity, the static, spherically symmetric black hole solutions in the infrared limit are corrected by non-perturbative effects. Specifically, the metric is modified by the running of gravitational couplings. In this work, we investigate the effects of this correction to the quasinormal modes (QNMs) of a test scalar field propagating in this kind of black hole background analytically and numerically. It is found that although the quasi-period frequencies and the damping of oscillations are respectively enhanced and weakened by the quantum correction term, the stability of the black hole remains.Comment: 11 pages, 1 figures, accepted for publication in CQG. arXiv admin note: text overlap with arXiv:1007.131

A Note on Self-gravitating Radiation in AdS Spacetime

In this paper we investigate the equilibrium self-gravitating radiation in higher dimensional, plane symmetric anti-de Sitter space. We find that there exist essential differences from the spherically symmetric case: In each dimension ($d\geq 4$), there are maximal mass (density), maximal entropy (density) and maximal temperature configurations, they do not appear at the same central energy density; the oscillation behavior appearing in the spherically symmetric case, does not happen in this case; and the mass (density), as a function of the central energy density, increases first and reaches its maximum at a certain central energy density and then decreases monotonically in $4\le d \le 7$, while in $d \geq 8$, besides the maximum, the mass (density) of the equilibrium configuration has a minimum: the mass (density) first increases and reaches its maximum, then decreases to its minimum and then increases to its asymptotic value monotonically. The reason causing the difference is discussed.Comment: Revtex, 13 pages with 8 eps figures, to appear in PRD; v2: typos corrected and the version in PR

Extremum Seeking Control of Hybrid Ground Source Heat Pump System

The ground source heat pump (GSHP) technology is a renewable alternative for space conditioning by rejecting/absorbing heat to/from the ground, which has demonstrated higher energy efficiency for residential and commercial buildings. As the system capacity is limited by the initial cost of construction of ground-loop heat exchanger (GHE), developing the so-called Hybrid GSHP system by utilizing supplemental heat rejecters such as cooling towers has emerged as a cost-effective alternative. In practice, operational efficiency of Hybrid GSHP system mainly depends on 1) the actual characteristics of heat pump, cooling tower, GHE and other equipment; 2) ambient air and ground conditions. In particular, the GHE heat transfer is heavily affected by the ground thermal characteristics which, however, is difficult and expensive in practice to determine due to the complexity of soil type and distribution. In addition, the actual cooling tower characteristics can vary significantly. Such uncertainties bring forth dramatic difficulty for successful application of model based control or optimization methods. In this study, an extremum seeking control (ESC) strategy is proposed for efficient operation of a hybrid GSHP system with cooling tower, which minimizes the total power (i.e. GHE loop water pump, cooling tower fan and pump, and the heat-pump compressor) consumption by tuning the air-flow rate of the cooling tower fan and the GHE loop water flow rate. To evaluate the proposed control method, a Modelica based model of the Hybrid GSHP system is developed by utilizing the Buildings Library developed by the Lawrence Berkeley National Laboratory, which consists of a 20-borehole GHE, a water-to-water heat pump, a counter-flow cooling tower and a plate heat exchanger. The transient conduction model of vertical GHE in the Buildings Library is adopted, which is based on a finite-volume method inside the borehole and cylindrical source model outside the borehole. A variable-flow water pump model is constructed for the GHE water loop, which gives power consumption under different operating scenarios. A cooling tower model in the Buildings Library is adopted, which is a static polynomial model based on a York cooling tower correlation. The relative air flow rate can be regulated to maintain the leaving water temperature at the setpoint, and then the corresponding fan power consumption is obtained. The heat pump model is based on the evaporator temperature, condenser temperature and Carnot efficiency. An inner-loop proportional-integral (PI) controller is implemented to regulate the evaporator leaving water temperature at 7 deg-C. Under the air wet-bulb temperature of 35 deg-C and dry-bulb temperature 23 deg-C, steady-state simulation of the plant model yields the static map of the total power with respect to the cooling tower relative air flow rate and the GHE water flow rate, which indicates about 25% power variation across the adjustable range of inputs. Simulation was conducted in two conditions: change in evaporator inlet water temperature and change in ambient air condition. The simulation study under way is to validate the effectiveness of the proposed ESC strategy, and the potential for energy saving will also be evaluated