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We study the effects of the generalized uncertainty principle (GDP) on the efficiency of quantum heat engines based on a particle in an infinite square well using the partition function approach. In particular, we study the Carnot and Otto heat engines. For the system we used, the GDP-corrected efficiencies turned out to be lower than efficiencies without the GUP effects. However, as expected, GUP effects increase as the temperature of the cold heat bath decreases and as the width of the potential well decreases. [ABSTRACT FROM AUTHOR]

An evaluation of the physical science section of the Medical College Admission Test is presented. Sample physics questions are presented to help students prepare for the test.

We propose that gravity, when formulated in the quantum level, can make quantum effects more pronounced. This is demonstrated by considering the effect of the generalized uncertainty principle or GUP (a consequence of quantum gravity theories) on entanglement (a quantum effect). We apply the GUP to continuous-variable systems. In particular, we study the following cases: the modified uncertainty relation of two identical entangled particles [G. Rigolin, Found. Phys. Lett. 15, 293 (2002)], and the inseparability conditions for entangled particles in the bipartite [Duan et al., Phys. Rev. Lett. 84, 2722 (2000)] and tripartite [van Loock and Furusawa, Phys Rev A 67, 052315 (2003)] cases. Rigolin showed a decrease in the lower bound of the product of the uncertainties of the position and momentum for two identical entangled particles while Duan and van Loock derived inseparability conditions for Einstein-Podolsky-Rosen-like (EPR-like) operators. In all three cases, the GUP correction resulted in a higher value of the bounds: a higher lower bound for the Rigolin's result and a higher upper bound for the inseparability condition in Duan and van Loock's relations. In Rigolin's case, the GUP correction decreased the disagreement with the Heisenberg uncertainty relation while in Duan's and Loock's case, the inseparability and entanglement conditions are enhanced. Interestingly, the GUP corrections tend to boost quantum mechanical effects. [ABSTRACT FROM AUTHOR]

A supersymmetric Sp (6)× U (1) model (SUSY Sp(6)) is proposed as an extension of the standard electroweak model. The model is applied in a phenomenological study of B $$\overline b $$ mixing. It is found that the supersymmetric (SUSY) partner z of the extra Z′ can significantly cancel the other contributions to bring the mixing parameter x within the experimentally allowed range 0.57≲ x ≲0.77 for a top mass of 158≲ m ≲194 GeV. Other interesting and possibly novel features of flavor-changing neutral currents (FCNC) in SUSY theories with horizontal gauge symmetries are pointed out. [ABSTRACT FROM AUTHOR]