Nonmonotonic energy harvesting efficiency in biased exciton chains

We theoretically study the efficiency of energy harvesting in linear exciton chains with an energy bias, where the initial excitation is taking place at the high-energy end of the chain and the energy is harvested (trapped) at the other end. The efficiency is characterized by means of the average time for the exciton to be trapped after the initial excitation. The exciton transport is treated as the intraband energy relaxation over the states obtained by numerically diagonalizing the Frenkel Hamiltonian that corresponds to the biased chain. The relevant intraband scattering rates are obtained from a linear exciton-phonon interaction. Numerical solution of the Pauli master equation that describes the relaxation and trapping processes, reveals a complicated interplay of factors that determine the overall harvesting efficiency. Specifically, if the trapping step is slower than or comparable to the intraband relaxation, this efficiency shows a nonmonotonic dependence on the bias: it first increases when introducing a bias, reaches a maximum at an optimal bias value, and then decreases again because of dynamic (Bloch) localization of the exciton states. Effects of on-site (diagonal) disorder, leading to Anderson localization, are addressed as well.Comment: 9 pages, 6 figures, to appear in Journal of Chemical Physic

Comparison of plasmakinetic transurethral resection of the prostate with monopolar transurethral resection of the prostate in terms of urethral stricture rates in patients with comorbidities

PurposeTo compare urethral stricture rates in comorbid patients undergoing plasmakinetic transurethral resection of the prostate (PK-TURP) and monopolar transurethral resection of the prostate (M-TURP) for benign prostatic hyperplasia.MethodsThe data of 317 patients with comorbidities undergoing either PK-TURP or M-TURP from September 2008 to December 2012 were retrospectively evaluated. Preoperative and postoperative 12-month International Prostate Symptom Score, maximal flow rate, postoperative International Index of Erectile Function scores, and urethral stricture rates were evaluated.ResultsA total of 154 patients underwent M-TURP and 163 patients underwent PK-TURP. Urethral stricture rates were 6/154 in the M-TURP treatment arm and 17/163 in the PK-TURP treatment arm (P=0.000). In the presence of hypertension and/or coronary artery disease and/or diabetes mellitus, the risk of urethral stricture complication was significantly higher in the PK-TURP group than in the M-TURP group (P=0.000).ConclusionsThe risk of urethral stricture increases with PK-TURP in elderly patients with a large prostate and concomitant hypertension and/or coronary artery disease and/or diabetes mellitus. Therefore, PK-TURP should be performed cautiously in this group of benign prostatic hyperplasia patients