Charge separation in organic photovoltaic cells

We consider a simple model for the geminate electron-hole separation process in organic photovoltaic cells, in order to illustrate the influence of dimensionality of conducting channels on the efficiency of the process. The Miller-Abrahams expression for the transition rates between nearest neighbor sites was used for simulating random walks of the electron in the Coulomb field of the hole. The non-equilibrium kinetic Monte Carlo simulation results qualitatively confirm the equilibrium estimations, although quantitatively the efficiency of the higher dimensional systems is less pronounced. The lifetime of the electron prior to recombination is approximately equal to the lifetime prior to dissociation. Their values indicate that electrons perform long stochastic walks before they are captured by the collector or recombined. The non-equilibrium free energy considerably differs from the equilibrium one. The efficiency of the separation process decreases with increasing the distance to the collector, and this decrease is considerably less pronounced for the three dimensional system. The simulation results are in good agreement with the extension of the continuum Onsager theory that accounts for the finite recombination rate at nonzero reaction radius and non-exponential kinetics of the charge separation process

Persistent primitive hypoglossal artery: an incidental autopsy finding and its significance in clinical practice

Persistent primitive hypoglossal artery (PPHA) is a recognised, albeit infrequent, intracranial vascular anomaly usually detected during angiography. Its presence is associated with an increased incidence of aneurysm, arteriovenous malformation and ischaemic stroke. A unique case of PHHA discovered during autopsy is described. Additionally, the significance of PPHA in neuroscience is discussed in detail

A study on the morphology of the popliteus muscle and arcuate popliteal ligament

The aim of this study was to investigate the origins and morphological features of the popliteus muscle in cadavers. In a sample of 40 lower limbs taken from cadavers the exact morphological features of the popliteus muscle were examined. In 100% of the cases studied we noticed, apart from the known femoral origin from the lateral femoral epicondyle, a fibular origin from the styloid process of the head of the fibula directed obliquely and blending with the main femoral origin, forming the arms of a Y-shaped structure. In all the cases a capsular origin was presented, while in 91.67% an origin lateral to it from the superior border of the posterior horn of the lateral meniscus was found. The capsular and meniscal origins formed the base of the Y-shaped structure that corresponded to the known arcuate ligament. We consider that the additional origins of the popliteus muscle form the arcuate ligament, which is not a distinct anatomical structure as it is described in traditional anatomical textbooks. In addition, we have analysed the exact morphological features of the capsular, fibular and meniscal origins of the popliteal muscle

Laparoscopic Approach to Incarcerated and Strangulated Inguinal Hernias

Introduction: Acute inguinal hernias are a common presentation as surgical emergencies, which have been routinely managed with open surgery. In recent years, the laparoscopic approach has been described by several authors but has been controversial amongst surgeons. We describe the laparoscopic approach to incarcerated/strangulated inguinal hernias based on a review of the literature with regards to its feasibility in laparoscopically managing the acute hernia presentation. Methods: A systematic literature search was carried out including Medline with PubMed as the search engine, and Ovid, Embase, Cochrane Collaboration, and Google Scholar databases to identify articles reporting on laparoscopic treatment, reduction, and repair of incarcerated or strangulated inguinal hernias from 1989 to 2008. Results: Forty-three articles were found, and 7 were included according to the inclusion criteria set. Articles reporting on the use of laparoscopy for the evaluation of the hernia but not reducing and repairing it, the use of the open technique, elective hernia repairs, pediatric series, review articles, and other kinds of hernias were excluded after title and abstract review. This resulted in 16 articles that were reviewed in full. Of these 16 articles, 7 reported on the use of the laparoscopic approach exclusively. From these 7 studies, there were 328 cases reported, 6 conversions, average operating time of 61.3 minutes (SD 12.3), average hospital stay of 3.8 days (SD 1.2), 34 complications (25 of which were reported as minor), and 17 bowel resections performed either laparoscopically or through a minilaparotomy incision guided laparoscopically. Conclusion: The laparoscopic repair is a feasible procedure with acceptable results; however, its efficacy need

An accessory middle scalene muscle causing thoracic outlet syndrome

The aim of our study is to present a very rare accessory middle scalene muscle, leading to thoracic outlet syndrome. In particular, a muscular bundle was discovered on a male cadaver connecting the middle portion of the middle scalene muscle with the anterior scalene muscle insertion to Lisfranc`s tubercle. This triangular accessory muscle and, especially, its sharp medial border compressed the middle and lower trunk of the brachial plexus and the subclavian artery. This anomaly is of great importance because it emphasises the fact that it is not primarily the anterior scalene muscle that produces symptoms of thoracic outlet syndrome but the anterior displacement of the middle scalene muscle or its accessory muscular bands. We also present the relative international literature and the clinical significance of our finding

Morphological parameters of the acromion

The purpose of this study was to record the basic morphometric values of the acromion. Forty-four pairs of dried scapulas were reviewed. Acromial shape was evaluated in relation to sex, symmetry and presence of subacromial enthesophytes and classified according to Bigliani with the following results: type I (flat): 26.1%, type II (curved): 55.6% and type III (hooked): 18.1%. There was a greater percentage of type III in men (56.2% vs. 43.7%) and type I in women (56.5% vs. 43.4%). Acromial morphology was symmetric in 29 acromia (65.9%). Enthesophytes were most common in type III (75%). A rough inferior surface of the acromion was most frequently found in type III (81.2%). Nine other scapular osteological parameters were also measured. Many differences were noted between male and female scapulae. The great variety of morphological features is assumed to be related to rotator cuff pathology and other shoulder impairments

Editor's Choice - Delays to Surgery and Procedural Risks Following Carotid Endarterectomy in the UK National Vascular Registry.

OBJECTIVE: Guidelines recommend that patients suffering an ischaemic transient ischaemic attack (TIA) or stroke caused by carotid artery stenosis should undergo carotid endarterectomy (CEA) within 14 days. METHOD: The degree to which UK vascular units met this standard was examined and whether rapid interventions were associated with procedural risks. The study analysed patients undergoing CEA between January 2009 and December 2014 from 100 UK NHS hospitals. Data were collected on patient characteristics, intervals of time from symptoms to surgery, and 30-day postoperative outcomes. The relationship between outcomes and time from symptom to surgery was evaluated using multilevel multivariable logistic regression. RESULTS: In 23,235 patients, the median time from TIA/stroke to CEA decreased over time, from 22 days (IQR 10-56) in 2009 to 12 days (IQR 7-26) in 2014. The proportion of patients treated within 14 days increased from 37% to 58%. This improvement was produced by shorter times across the care pathway: symptoms to referral, from medical review to being seen by a vascular surgeon, and then to surgery. The spread of the median time from symptom to surgery among NHS hospitals shrank between 2009 and 2013 but then grew slightly. Low-, medium-, and high-volume NHS hospitals all improved their performance similarly. Performing CEA within 48 h of symptom onset was associated with a small increase in the 30-day stroke and death rate: 3.1% (0-2 days) compared with 2.0% (3-7 days); adjusted odds ratio 1.64 (95% CI 1.04-2.59) but not with longer delays. CONCLUSIONS: The delay from symptom to CEA in symptomatic patients with ipsilateral 50-99% carotid stenoses has reduced substantially, although 42% of patients underwent CEA after the recommended 14 days. The risk of stroke after CEA was low, but there may be a small increase in risk during the first 48 h after symptoms