Optical signatures of quantum delocalization over extended domains in photosynthetic membranes

The prospect of coherent dynamics and excitonic delocalization across several light-harvesting structures in photosynthetic membranes is of considerable interest, but challenging to explore experimentally. Here we demonstrate theoretically that the excitonic delocalization across extended domains involving several light-harvesting complexes can lead to unambiguous signatures in the optical response, specifically, linear absorption spectra. We characterize, under experimentally established conditions of molecular assembly and protein-induced inhomogeneities, the optical absorption in these arrays from polarized and unpolarized excitation, and demonstrate that it can be used as a diagnostic tool to determine the coherent coupling among iso-energetic light-harvesting structures. The knowledge of these couplings would then provide further insight into the dynamical properties of transfer, such as facilitating the accurate determination of F\"orster rates.Comment: 4 figures and Supplementary information with 7 figures. To appear in Journal of physical chemistry A, 201

Trauma cardiaco penetrante

Se revisan 100 casos de trauma cardíaco penetrante operados en el Hospital San Juan de Dios en los pasados 4 años; la rata global de mortalidad encontrada fue del 15.0%; se discuten los distintos elementos diagnósticos, se revisan y comparan otras publicaciones y se pasa revista sobre los diferentes aspectos fisiopatológicos y pronósticos de este tipo de trauma.This is a review of 100 cases of penetrating cardiac traum, who underwent surgery the Hospital San Juan de Dios during the past four years. Overall mortality was  5.0%.Díagnostíc procedures are analizad, as well as physiopathologic mechanisms and prognosis of this severe trauma. A review and comparison of the major publications in the literature are presented

Cumplimiento de las recomendaciones de prevención secundaria de enfermedad coronaria en pacientes sometidos a revascularización coronaria percutánea en el Hospital Universitario Fundación Santa Fe de Bogotá

Marco de referenciadiferentes ensayos clínicos han mostrado que el efecto de las revascularizaciones y los procedimientos de angioplastia en el pronóstico del paciente, tiene sólo un efecto a corto plazo, mientras que la prevención secundaria (cambio de estilo de vida y tratamiento intensivo) mejora el pronóstico a largo plazo.Objetivoevaluar el cumplimiento de las recomendaciones para prevención cardiovascular secundaria, de los pacientes sometidos a revascularización coronaria percutánea en el hospital universitario Fundación Santa Fe de Bogotá, entre los años 2008 y 2010.Materiales y métodosestudio descriptivo, ambispectivo, cuya población estuvo conformada por 332 pacientes sometidos a intervención coronaria percutánea atendidos entre enero de 2008 a diciembre de 2010 en el servicio de hemodinamia del Hospital Universitario Fundación Santa Fe de Bogotá. La recolección de la información se realizó mediante revisión de las historias clínicas de los pacientes y vía telefónica. Las metas de control se basaron en las recomendaciones de la Asociación Americana del Corazón y el Colegio Americano de Cardiología.Resultados332 pacientes fueron sometidos a revascularización coronaria percutánea y 4 fueron excluidos del estudio por falta de datos. La presentación clínica más frecuente fue la angina inestable (32,93%). Sólo se contactaron 172 (52,43%) pacientes, de los cuales 77,4% eran hombres y 22,6% mujeres. Únicamente 6 (3,5%) cumplían con el 100% de las recomendaciones para la prevención secundaria de enfermedad coronaria y 17% cumplía menos del 50% de éstas.Conclusionesla experiencia en la Fundación Santa Fe de Bogotá muestra un pobre cumplimiento de las metas de prevención secundaria de enfermedad coronaria.Contextdifferent clinical trials have shown that the effect of revascularization and angioplasty procedures in the prognosis of the patient has only a short-term effect, while secondary prevention (lifestyle change and intensive treatment) improves long-term prognosis.Objectiveto assess compliance with the recommendations for secondary prevention of cardiovascular disease in patients undergoing percutaneous coronary revascularization at the University Hospital Fundación Santa Fe de Bogotá, between 2008 and 2010.Materials and methodsa descriptive ambispective study, whose population was conformed by 332 patients undergoing percutaneous coronary intervention seen between January 2008 and December 2010 in the service of hemodynamics of the University Hospital Fundación Santa Fe de Bogotá. The data collection was conducted by reviewing the medical records of the patients and by telephone. Control targets were based on the recommendations of the American Heart Association and the American College of Cardiology.Results332 patients underwent percutaneous coronary revascularization. 4 were excluded from the study due to lack of data. The most common clinical presentation was unstable angina (32.93%). Only 172 patients (52.43%) were contacted. From these, 77.4% were male and 22.6% female. Only 6 (3.5%) met 100% of the recommendations for secondary prevention of coronary heart disease and 17% met less than 50% of these recommendations.Conclusionsthe experience in the Fundación Santa Fe de Bogotá shows a poor compliance with the goals of secondary prevention of coronary disease

Which-way interference within ringlike unit cells for efficient energy transfer

We show that which-way interference within ringlike unit cells enhances the propagation of electronic excitations (excitons) along linear arrays made upon these basic units. After providing an analytic approximate solution of the eigenvalue problem for such aggregates, we show that the constructive interference of wave packets leads to an excitonic population transferred across the array which is not a monotonic function of the coupling between nearest-neighbor rings. The nonmonotonicity depends on an interesting trade-off between the exciton transfer speed and the amount of energy transferred, arising from the interplay between paths within the ringlike cells and the interring coupling strength across the array

A Snapshot of the International Views of the Treatment of Rectal Cancer Patients, a Multi-regional Survey: International Tendencies in Rectal Cancer

BACKGROUND: Management of rectal cancer has a number of potentially appropriate alternatives for each patient. Despite acceptance of standards, practices may vary among regions. There is significant paucity of data in this area. The objective was to create a snapshot of the regional differences. DESIGN: This online survey included 10 questions. Enquiries focused on controversial topics, on surgeon and hospital volume, surgical margins, appropriateness of surgical approaches and techniques, watch-and-wait strategies, and total neoadjuvant therapy. Major colorectal surgery societies around the world were asked to invite their members to complete the survey. OUTCOME MEASURES: Frequency of responses across regions within each question was compared by Fisher's exact test. RESULTS: Seven hundred and fifty-three participants from 60 countries responded. Eight regions were identified, and four had sufficient representation for comparisons. Similarities and differences in the therapies among these regions were identified. Robotic surgery penetrance is higher in North America, and watch and wait is more accepted in South America. Patients in Oceania are more likely to be diverted; Europe has more usage of taTME. DISCUSSION: This online survey was practical as a mean to provide a rapid assessment of the international picture on consistency and variability of rectal cancer patients' care, and to potentially identify opportunities to standardized care to patients. Medical surveys have inherent limitations; pertinence to our study is selection bias. CONCLUSIONS: The management of rectal cancer varies among different regions. Identification of differences is important when considering global efforts to improve management and interpret data

Comparing ‘Twitter’ polls results with an online survey on surgeons perspectives for the treatment of rectal cancer

INTRODUCTION: Traditional surveys (including phone, mail and online) can be valuable tools to obtain information from specific communities. Social media apps such as Twitter are being increasingly adopted for knowledge dissemination and research purposes. Twitter polls are a unique feature which allows for a rapid response to questions posed. Nonetheless Twitter does not constitute a validated survey technique. The objective was to compare the similarities of Twitter polls in describing practice patterns for the treatment of rectal cancer. METHODS: A survey on the management of rectal cancer was designed using modified Delphi methodology. Surgeons were contacted through major colorectal societies to participate in an online survey. The same set of questions were periodically posted by influencers on Twitter polls and the results were compared. RESULTS: A total of 753 surgeons participated in the online survey. Individual participation in Twitter ranged from 162 to 463 responses. There was good and moderate agreement between the two methods for the most popular choice (9/10) and the least popular choice (5/10), respectively. DISCUSSION: It is possible that in the future polls available via social media can provide a low-cost alternative and an efficient, yet pragmatic method to describe clinical practice patterns. This is the first study comparing Twitter polls with a traditional survey method in medical research. CONCLUSIONS: There is viable opportunity to enhance the performance of research through social media, however, significant refinement is required. These results can potentially be transferable to other areas of medicine

Origin of Long Lived Coherences in Light-Harvesting Complexes

A vibronic exciton model is developed to investigate the origin of long lived coherences in light-harvesting complexes. Using experimentally determined parameters and uncorrelated site energy fluctuations, the model predicts oscillations in the nonlinear spectra of the Fenna-Matthews-Olson (FMO) complex with a dephasing time of 1.3 ps at 77 K. These oscillations correspond to the coherent superposition of vibronic exciton states with dominant contributions from vibrational excitations on the same pigment. Purely electronic coherences are found to decay on a 200 fs timescale.Comment: 4 pages, 2 figure

Integration of energy and electron transfer processes in the photosynthetic membrane of Rhodobacter sphaeroides

Photosynthesis converts absorbed solar energy to a protonmotive force, which drives ATP synthesis. The membrane network of chlorophyll–protein complexes responsible for light absorption, photochemistry and quinol (QH2) production has been mapped in the purple phototrophic bacterium Rhodobacter (Rba.) sphaeroides using atomic force microscopy (AFM), but the membrane location of the cytochrome bc1 (cytbc1) complexes that oxidise QH2 to quinone (Q) to generate a protonmotive force is unknown. We labelled cytbc1 complexes with gold nanobeads, each attached by a Histidine10 (His10)-tag to the C-terminus of cytc1. Electron microscopy (EM) of negatively stained chromatophore vesicles showed that the majority of the cytbc1 complexes occur as dimers in the membrane. The cytbc1 complexes appeared to be adjacent to reaction centre light-harvesting 1-PufX (RC–LH1–PufX) complexes, consistent with AFM topographs of a gold-labelled membrane. His-tagged cytbc1 complexes were retrieved from chromatophores partially solubilised by detergent; RC–LH1–PufX complexes tended to co-purify with cytbc1 whereas LH2 complexes became detached, consistent with clusters of cytbc1 complexes close to RC–LH1–PufX arrays, but not with a fixed, stoichiometric cytbc1–RC–LH1–PufX supercomplex. This information was combined with a quantitative mass spectrometry (MS) analysis of the RC, cytbc1, ATP synthase, cytaa3 and cytcbb3 membrane protein complexes, to construct an atomic-level model of a chromatophore vesicle comprising 67 LH2 complexes, 11 LH1–RC–PufX dimers & 2 RC–LH1–PufX monomers, 4 cytbc1 dimers and 2 ATP synthases. Simulation of the interconnected energy, electron and proton transfer processes showed a half-maximal ATP turnover rate for a light intensity equivalent to only 1% of bright sunlight. Thus, the photosystem architecture of the chromatophore is optimised for growth at low light intensities

Contemporary Management of Locally Advanced and Recurrent Rectal Cancer: Views from the PelvEx Collaborative

Pelvic exenteration is a complex operation performed for locally advanced and recurrent pelvic cancers. The goal of surgery is to achieve clear margins, therefore identifying adjacent or involved organs, bone, muscle, nerves and/or vascular structures that may need resection. While these extensive resections are potentially curative, they can be associated with substantial morbidity. Recently, there has been a move to centralize care to specialized units, as this facilitates better multi-disciplinary care input. Advancements in pelvic oncology and surgical innovation have redefined the boundaries of pelvic exenterative surgery. Combined with improved neoadjuvant therapies, advances in diagnostics, and better reconstructive techniques have provided quicker recovery and better quality of life outcomes, with improved survival This article provides highlights of the current management of advanced pelvic cancers in terms of surgical strategy and potential future developments