Coherent exciton dynamics in the presence of underdamped vibrations

Recent ultrafast optical experiments show that excitons in large biological light-harvesting complexes are coupled to molecular vibration modes. These high-frequency vibrations will not only affect the optical response, but also drive the exciton transport. Here, using a model dimer system, the frequency of the underdamped vibration is shown to have a strong effect on the exciton dynamics such that quantum coherent oscillations in the system can be present even in the case of strong noise. Two mechanisms are identified to be responsible for the enhanced transport efficiency: critical damping due to the tunable effective strength of the coupling to the bath, and resonance coupling where the vibrational frequency coincides with the energy gap in the system. The interplay of these two mechanisms determines parameters responsible for the most efficient transport, and these optimal control parameters are comparable to those in realistic light-harvesting complexes. Interestingly, oscillations in the excitonic coherence at resonance are suppressed in comparison to the case of an off-resonant vibration

Should I stay or should I go? Hormonal and demographic correlates of natal dispersal in a population of wild vervet monkeys

Natal dispersal is an important maturational milestone in the life of many primates and is associated with changes in the physical and social environment. To integrate into an unrelated group, an individual must abandon its known environment and face various challenges which can often be costly. Male dispersal is most common among Old World monkeys, but is poorly studied due to the difficulty of following dispersing individuals. Even fewer studies have attempted to explore the hormonal correlates of dispersal owing to the difficulties of obtaining sufficient faecal samples of the same individuals before, during and after a successful dispersal. In this study, I aimed to better understand the hormonal correlates (i.e. testosterone and cortisol) of dispersal in free ranging, habituated male vervets leaving their natal groups (natal dispersal). I collected faecal samples from 10 males and assessed the effects of age, rank, natal group size, adult sex ratio and number of same sex peers, to investigate potential influences on the triggers for natal male dispersal. My results show that standardised rank, but not testosterone levels, was significantly lower in the three months following a successful primary dispersal than before the animals left their natal group. Natal males from larger groups had significantly higher testosterone levels than those from smaller groups and dispersed significantly later than males from smaller groups. Cortisol levels were rarely above the minimum detection level, suggesting dispersal in vervets is not a stressful behaviour, possibly because of high levels of familiarity with individuals in troops into which males had immigrated. Limitations included the difficulty of following known individuals into habituated study troops, which resulted in a relatively small sample size of successfully dispersing males. Furthermore, a lack of adequate faecal samples at key points in the life history of individuals reduced resolution on pre- and post- dispersal hormonal correlates. Further studies will require a larger proportion of the study population to be habituated and regularly followed to allow for a more rigorous assessment of dispersal success and hormonal correlates. This study advances the limited knowledge we have on the potential drivers of male dispersal in vervets and primates more generally

Histopathologic Outcomes of Robotic Radical Prostatectomy

Robotically assisted laparoscopic radical prostatectomy is a minimally invasive alternative for the treatment of prostate cancer. We report the histopathologic and shortterm PSA outcomes of 500 robotic radical prostatectomies. Five hundred patients underwent robotic radical prostatectomy. The procedure was performed via a six trocar transperitoneal technique. Prostatectomy specimens were analyzed for TNM stage, Gleason’s grade, tumor location, volume, specimen weight, seminal vesicle involvement, and margin status. A positive margin was reported if cancer cells were found at the inked specimen margin. PSA data were collected every 3 months for the first year, then every 6 months for a year, then yearly. The average preoperative PSA was 6.9 (1–90) with Gleason’s score of 5 (2%), 6 (52%), 7 (40%), 8 (4%), and 9 (2%); postoperatively, histopathologic analysis showed Gleason's 6 (44%), 7 (42%), 8 (10%), and 9 (4%); 10, 5, 63, 15, 5, and 2% had pathologic stage T2a, T2b, T2c, T3a, T3b, and T4, respectively. Positive margin rate was 9.4% for the entire series. The positive margin rate per 100 cases was: 13% (1–100), 8% (101–200), 13% (201–300), 5% (301–400), and 8% (401–500). By stage, it was 2, 4, and 2.5% for T2a, T2b, T2c tumors; 23% (T3a), 46% (T3b), and 53% (T4a). For organ-confined disease (T2), the margin rate was 2.5% and it was 31% for nonorgan-confined disease. There were a total of 47 positive margins, 26 (56%) posterolateral, 4 (8.5%) apical, 4 (8.5%) bladder neck, 2 (4%) seminal vesicle, and 11 (23%) multifocal. Ninety-five percent of patients (n = 500) have undetectable PSA (<0.1) at average follow-up of 9.7 months. Recurrence has only been seen with nonorgan-confined tumors. Of those patients with a minimum follow-up of 1 year (average 15.7 months), 95% have undetectable PSA (<0.1). Our initial experience with robotic radical prostatectomy is promising. Histopathologic outcomes are acceptable with a low overall, positive margin rate. Shortterm biochemical recurrence-free survival has also been good. We believe that the precise dissection allowed by the advantages of laparoscopic robotic surgery will translate into excellent long-term oncologic outcomes. At this time, the lack of maturity of the PSA data prevent definitive comparison to the open approach

Diffusion mechanisms of localised knots along a polymer

We consider the diffusive motion of a localized knot along a linear polymer chain. In particular, we derive the mean diffusion time of the knot before it escapes from the chain once it gets close to one of the chain ends. Self-reptation of the entire chain between either end and the knot position, during which the knot is provided with free volume, leads to an L^3 scaling of diffusion time; for sufficiently long chains, subdiffusion will enhance this time even more. Conversely, we propose local ``breathing'', i.e., local conformational rearrangement inside the knot region (KR) and its immediate neighbourhood, as additional mechanism. The contribution of KR-breathing to the diffusion time scales only quadratically, L^2, speeding up the knot escape considerably and guaranteeing finite knot mobility even for very long chains.Comment: 7 pages, 2 figures. Accepted to Europhys. Let

Review Essay: C. S. Lewis and His Circle: Essays and Memoirs from the C. S. Lewis Society

Three reviews of Roger White, Judith Wolfe, and Brendan N. Wolfe, eds., C. S. Lewis and His Circle: Essays and Memoirs from the C. S. Lewis Society (Oxford, 2015). 273 pages. $29.95. ISBN 9780190214340

Myotonic dystrophy: The burden for patients and their partners

Objective: Dystrophia myotonica is characterized by progressive muscular weakness, myotonia, mental slowness and lack of initiative, which causes problems in daily life both for patients and for their spouses. Some couples seem to deal with these problems satisfactorily, while for others they are quite burdensome. The aim of this study was to describe the relationship of severity of dystrophia myotonica and psychological wellbeing in patients and partners. Methods: Sixty-nine couples, in whom one partner had dystrophia myotonica, completed questionnaires on severity of dystrophia myotonica, marital satisfaction, anxiety and depression (Hospital Anxiety and Depression Scale), hopelessness (Beck Hopelessness Scale) and general psychological health (General Health Questionnaire-12). Results: For patients, a worse view of the future, worse general wellbeing, more anxiety and more depression was associated with a greater need for help. For partners, worse general wellbeing and more anxiety was associated with a lack of initiative of the patient and less marital satisfaction. It is noteworthy that 40% of patients and particularly female partners had Beck Hopelessness Scale scores suggestive of clinically relevant depression. Conclusion: Dystrophia myotonica places a heavy burden on patients, and especially on female partners. The need for help and dependency has more influence on the wellbeing of patients than the symptoms of dystrophia myotonica themselves. Marital satisfaction is a strong predictor of better wellbeing, both for patients and, even more so, for partners

Terahertz electromodulation spectroscopy of electron transport in GaN

Time-resolved terahertz (THz) electromodulation spectroscopy is applied to investigate the high-frequency transport of electrons in gallium nitride at different doping concentrations and densities of threading dislocations. At THz frequencies, all structures reveal Drude transport. The analysis of the spectral response provides the fundamental transport properties, such as the electron scattering time and the electrons’ conductivity effective mass. We observe the expected impact of ionized-impurity scattering and that scattering at threading dislocations only marginally affects the high-frequency mobility.The research was supported by the German Science Foundation DFG under grants Ke 516/1-2 and Ke 516/6- 1.This is the accepted manuscript. The final version is available at http://scitation.aip.org/content/aip/journal/apl/106/9/10.1063/1.4914326

Interference of multi-mode photon echoes generated in spatially separated solid-state atomic ensembles

High-visibility interference of photon echoes generated in spatially separated solid-state atomic ensembles is demonstrated. The solid state ensembles were LiNbO$_3$ waveguides doped with Erbium ions absorbing at 1.53 $\mu$m. Bright coherent states of light in several temporal modes (up to 3) are stored and retrieved from the optical memories using two-pulse photon echoes. The stored and retrieved optical pulses, when combined at a beam splitter, show almost perfect interference, which demonstrates both phase preserving storage and indistinguishability of photon echoes from separate optical memories. By measuring interference fringes for different storage times, we also show explicitly that the visibility is not limited by atomic decoherence. These results are relevant for novel quantum repeaters architectures with photon echo based multimode quantum memories

Avaliação da formação de compostos fenólicos em resíduos contendo benzeno após aplicação de processo fenton.

Projeto/Plano de Ação: 16.300.30004-00