Work fluctuations for Bose particles in grand canonical initial states

We consider bosons in a harmonic trap and investigate the fluctuations of the work performed by an adiabatic change of the trap curvature. Depending on the reservoir conditions such as temperature and chemical potential that provide the initial equilibrium state, the exponentiated work average (EWA) defined in the context of the Crooks relation and the Jarzynski equality may diverge if the trap becomes wider. We investigate how the probability distribution function (PDF) of the work signals this divergence. It is shown that at low temperatures the PDF is highly asymmetric with a steep fall off at one side and an exponential tail at the other side. For high temperatures it is closer to a symmetric distribution approaching a Gaussian form. These properties of the work PDF are discussed in relation to the convergence of the EWA and to the existence of the hypothetical equilibrium state to which those thermodynamic potential changes refer that enter both the Crooks relation and the Jarzynski equality.Comment: 9 pages, 4 figure

Reduction of Activation Energy Barrier of Stone-Wales Transformation in Endohedral Metallofullerenes

We examine effects of encapsulated metal atoms inside a C$_{60}$ molecule on the activation energy barrier to the Stone-Wales transformation using {\it ab initio} calculations. The encapsulated metal atoms we study are K, Ca and La which nominally donate one, two and three electrons to the C$_{60}$ cage, respectively. We find that isomerization of the endohedral metallofullerene via the Stone-Wales transformation can occur more easily than that of the empty fullerene owing to the charge transfer. When K, Ca and La atoms are encapsulated inside the fullerene, the activation energy barriers are lowered by 0.30, 0.55 and 0.80 eV, respectively compared with that of the empty C$_{60}$ (7.16 eV). The lower activation energy barrier of the Stone-Wales transformation implies the higher probability of isomerization and coalescence of metallofullerenes, which require a series of Stone-Wales transformations.Comment: 13 pages, 3 figures, 1 tabl

Quantum states for perfectly secure secret sharing

In this work, we investigate what kinds of quantum states are feasible to perform perfectly secure secret sharing, and present its necessary and sufficient conditions. We also show that the states are bipartite distillable for all bipartite splits, and hence the states could be distillable into the Greenberger-Horne-Zeilinger state. We finally exhibit a class of secret-sharing states, which have an arbitrarily small amount of bipartite distillable entanglement for a certain split.Comment: 4 page

Comparing peak and submaximal cardiorespiratory responses during field walking tests with incremental cycle ergometry in COPD

Background and objective: Field and laboratory-based tests are used to measure exercise capacity in people with COPD. A comparison of the cardiorespiratory responses to field tests, referenced to a laboratory test, is needed to appreciate the relative physiological demands. We sought to compare peak and submaximal cardiorespiratory responses to the 6-min walk test, incremental shuttle walk test and endurance shuttle walk test with a ramp cycle ergometer test (CET) in patients with COPD. Methods: Twenty-four participants (FEV1 50 ± 14%; 66.5 ± 7.7 years; 15 men) completed four sessions, separated by ≥24 h. During an individual session, participants completed either two 6-min walk tests, incremental shuttle walk tests, endurance shuttle walk tests using standardized protocols, or a single CET, wearing a portable gas analysis unit (Cosmed K4b2) which included measures of heart rate and arterial oxygen saturation (SpO2). Results: Between tests, no difference was observed in the peak rate of oxygen uptake (F3,69 = 1.2; P = 0.31), end-test heart rate (F2,50 = 0.6; P = 0.58) or tidal volume (F3,69 = 1.5; P = 0.21). Compared with all walking tests, the CET elicited a higher peak rate of carbon dioxide output (1173 ± 350 mL/min; F3,62 = 4.8; P = 0.006), minute ventilation (48 ± 17 L/min; F3,69 = 10.2; P < 0.001) and a higher end-test SpO2 (95 ± 4%; F3,63 = 24.9; P < 0.001). Conclusions: In patients with moderate COPD, field walking tests elicited a similar peak rate of oxygen uptake and heart rate as a CET, demonstrating that both self- and externally paced walking tests progress to high intensities

Polymer Translocation in Crowded Environments

We study the effect of the crowded nature of the cellular cytoplasm on the translocation of a polymer through a pore in a membrane. By systematically treating the entropic penalty due to crowding, we show that the translocation dynamics are significantly altered, leading to novel scaling behaviors of the translocation time in terms of chain length. We also observe new and qualitatively different translocation regimes depending upon the extent of crowding, transmembrane chemical potential asymmetry, and polymer length.Comment: 4 figure

A Non-Oxidative Approach toward Chemically and Electrochemically Functionalizing Si(111)

A general method for the non-oxidative functionalization of single-crystal silicon(111) surfaces is described. The silicon surface is fully acetylenylated using two-step chlorination/alkylation chemistry. A benzoquinone-masked primary amine is attached to this surface via Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (“click” chemistry). The benzoquinone is electrochemically reduced, resulting in quantitative cleavage of the molecule and exposing the amine terminus. Molecules presenting a carboxylic acid have been immobilized to the exposed amine sites. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and contact angle goniometry were utilized to characterize and quantitate each step in the functionalization process. This work represents a strategy for providing a general platform that can incorporate organic and biological molecules on Si(111) with minimal oxidation of the silicon surface

The role of electronic triplets and high-lying singlet states in the deactivation mechanism of the parent BODIPY: An ADC(2) and CASPT2 study

The potential tunability of the spectroscopic properties of the BODIPY parent dye by suitable functionalization makes it attractive for a number of applications. Unfortunately, its strong fluorescence against minor intersystem crossing to the triplet states prevents its application in photodynamic therapy. With the perspective of designing BODIPY derivatives with enhanced intersystem crossing, the goal of this work is two-fold: (i) investigate the main deactivation channels of the parent BODIPY following irradiation, paying particular attention to the accessibility of the triplet state potential energy surfaces, as well as the non-radiative pathways involving the second brightest more stable singlet electronic state, S2, and (ii) evaluate the performance of the computationally efficient second order algebraic-diagrammatic construction scheme for the polarization propagator, (ADC(2)) against the complete active space second-order perturbation theory (CASPT2) method. Three singlet/triplet crossings were found, all of them with small spin-orbit couplings, being the S1/T2 crossing the most plausible for the observed intersystem crossing yield. Methodologically, it is found that the ADC(2) method qualitatively reproduces the landscape of the potential energy profiles for the photophysical processes investigated; however, it systematically underestimates the energies of the stationary points and crossings of the same and different multiplicity, with the largest discrepancies found at S1/S0 crossing points. Our CASPT2 results provide a comprehensive picture of the landscape of the excited state potential energy surfaces of the parent BODIPY that might serve as a basis for the rational design of photosensitizers with a particular photophysical profileThis work has been supported by the Project CTQ2015-63997- C2 of the Ministerio de Economía y Competitividad of Spain. I.C. gratefully acknowledges the “Ramón y Cajal” program of the Ministerio de Economía y Competitividad of Spain. M.D.V. thanks the Marie Curie Actions, within the Innovative Training Network-European Join Doctorate in Theoretical Chemistry and Computational Modelling TCCM-ITN-EJD-642294, for financial suppor

Van der Waals forces in density functional theory: perturbational long-range electron interaction corrections

Long-range exchange and correlation effects, responsible for the failure of currently used approximate density functionals in describing van der Waals forces, are taken into account explicitly after a separation of the electron-electron interaction in the Hamiltonian into short- and long-range components. We propose a "range-separated hybrid" functional based on a local density approximation for the short-range exchange-correlation energy, combined with a long-range exact exchange energy. Long-range correlation effects are added by a second-order perturbational treatment. The resulting scheme is general and is particularly well-adapted to describe van der Waals complexes, like rare gas dimers.Comment: 8 pages, 1 figure, submitted to Phys. Rev.

Homogeneous Gold Catalysis through Relativistic Effects: Addition of Water to Propyne

In the catalytic addition of water to propyne the Au(III) catalyst is not stable under non-relativistic conditions and dissociates into a Au(I) compound and Cl2. This implies that one link in the chain of events in the catalytic cycle is broken and relativity may well be seen as the reason why Au(III) compounds are effective catalysts.Comment: 12 pages, 3 figures, 1 tabl

BMI, All-Cause and Cause-Specific Mortality in Chinese Singaporean Men and Women: The Singapore Chinese Health Study

Background: The optimal range of relative weight for morbidity and mortality in Asian populations is an important question in need of more thorough investigation, especially as obesity rates increase. We aimed to examine the association between body mass index (BMI), all cause and cause-specific mortality to determine the optimal range of BMI in relation to mortality in Chinese men and women in Singapore. Methodology/Principal Findings: We analyzed data from a prospective cohort study of 51,251 middle-aged or older (45– 74) Chinese men and women in the Singapore Chinese Health Study. Participants were enrolled and data on body weight and covariates were collected in 1993–1998 and participants were followed through 2008. The analysis accounted for potential methodological issues through stratification on smoking and age, thorough adjustment of demographic and lifestyle confounders and exclusion of deaths early in the follow-up. Conclusions/Significance: Increased risk of mortality was apparent in underweight (,18.5) and obese BMI categories ($27.5) independent of age and smoking. Regardless of age or BMI, smoking considerably increased the rate of mortality and modified the association between BMI and mortality. The most favorable range of BMI for mortality rates and risk in non-smoking persons below age 65 was 18.5–21.4 kg/m 2, and for non-smoking persons aged 65 and above was 21.5