418 research outputs found
Casimir effect of an ideal Bose gas trapped in a generic power-law potential
The Casimir effect of an ideal Bose gas trapped in a generic power-law
potential and confined between two slabs with Dirichlet, Neumann, and periodic
boundary conditions is investigated systematically, based on the grand
potential of the ideal Bose gas, the Casimir potential and force are
calculated. The scaling function is obtained and discussed. The special cases
of free and harmonic potentials are also discussed. It is found that when T<Tc
(where Tc is the critical temperature of Bose-Einstein condensation), the
Casimir force is a power-law decay function; when T>Tc, the Casimir force is an
exponential decay function; and when T>>Tc, the Casimir force vanishes.Comment: 5 pages, 1 figur
Sharp Stability of Log-Sobolev and Moser-Onofri inequalities on the Sphere
In this paper, we are concerned with the stability problem for endpoint
conformally invariant cases of the Sobolev inequality on the sphere
. Namely, we will establish the stability for Beckner's
log-Sobolev inequality and Beckner's Moser-Onofri inequality on the sphere. We
also prove that the sharp constant of global stability for the log-Sobolev
inequality on the sphere must be strictly smaller than the sharp
constant of local stability for the same inequality. Furthermore, we also
derive the non-existence of the global stability for Moser-Onofri inequality on
the sphere .Comment: 22 page
On the equivalence of the Nernst theorem and its consequence
One general consequence of the Nernst theorem is derived, i.e., the various
heat capacities of a thermodynamic system under different constraints approach
zero as the temperature approaches absolute zero. The temperature dependence of
the heat capacity of any thermodynamic system at ultra-low temperatures is
revealed through this consequence. Moreover, the general form and the simplest
expression of the heat capacities of thermodynamic systems at ultra-low
temperatures are deduced. Some significant discussion and results are given.
One new research method is provided by using this consequence. Finally, the
equivalence between the Nernst theorem and its consequence is rigorously
proved, so that this consequence may be referred to another description of the
third law of thermodynamics
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Role of Hydrogen Bonding in Green Fluorescent Protein-like Chromophore Emission.
The fluorescence emission from green fluorescent protein (GFP) is known to be heavily influenced by hydrogen bonding between the core fluorophore and the surrounding side chains or water molecules. Yet how to utilize this feature for modulating the fluorescence of GFP chromophore or GFP-like fluorophore still remains elusive. Here we present theoretical calculations to predict how hydrogen bonding could influence the excited states of the GFP-like fluorophores. These studies provide both a new perspective for understanding the photophysical properties of GFP as well as a solid basis for the rational design of GFP-based fluorophores
Relationship of Family Environment, Psychological Resilience, Campus Bullying with Tobacco Use among Preadolescents
Objective. To explore the relationship between family environment, psychological resilience, campus bullying and tobacco use in early adolescence. Methods. According to the principle of cluster sampling, 4,792 students from grade 4 to grade 6 in five primary schools in Baise City and county were selected from February to November 2018, including 2,522 males (52.63%), 2,236 females (46.66%)and 34 missing genders (0.71%); the average age was (11.8 ± 0.5) years; 2,721 students in urban areas (56.78%) and 2,071 students in county towns (43.22%); 4,313 Zhuang (90.00%), 365 Han (7.62%), 98 other ethnic groups (Yao, Miao, Yi, etc.) (2.05%). The General Family Environment Questionnaire, Adolescent Mental Resilience Scale, School Bullying Questionnaire, and Tobacco Use Questionnaire were used for evaluation, and logistic regression was used to analyze the effect relationship between the study variables. Results. 467 people tried to smoke, and the total detection rate was 9.75%. The number of smokers was 334, and the total detection rate was 6.97%. Boysâ tobacco attempt and smoking behavior were higher than girls (Ï2 were 57.230 and 56.013, P < 0. 001). Multivariate logistic regression analysis showed that the risk of tobacco attempt of boys was 2.37 times thanthat of girls (OR = 0.468, 95% CI 0.377 ~ 0.582), the risk of smoking in boys is 2.5 times that in girls 32 times (OR = 0.422, 95% CI 0.324 ~ 0.551); older adolescents had more tobacco attempts (OR = 1.609, 95% CI 1.446 ~ 1.791)and smoking behavior (OR = 2.026, 95% CI 1.776 ~ 2.310); campus bullying increased the risk of smoking behavior among adolescents (OR = 1.106, 95% CI 1.073 ~ 1.140). Psychological resilience (personal strength), family intimacy and family rules can effectively reduce the risk of adolescent tobacco attempts (personal strength, OR = 0.964, 95% CI = 0.951 ~ 0.976; family intimacy, OR = 0.946, 95% CI 0.892 ~ 0.984; family rules, OR = 0.949, 95% CI 0.930 ~ 0.965) and smoking behavior (personal strength, OR = 0.962, 95% CI 0.947 ~ 0.977; family intimacy, OR = 0.937, 95% CI 0.885 ~ 0.992; family rules, OR = 0.952, 95% CI 0.932 ~ 0.973). Conclusion. Campus bullying increases the risk of smoking behavior among adolescents. Psychological resilience (personal strength), family intimacy and family rules can effectively reduce teenagersâ tobacco attempts and smoking behavior
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