Pyrene–benzothiadiazole-based copolymers for application in photovoltaic devices

The preparation and characterisation of four narrow band gap pyrene-benzothiadiazole based alternating copolymers is presented. An investigation of the impact of attaching different solubilising groups to the pyrene repeat units on the optical, electrochemical and thermal properties of the resulting materials was undertaken along with studies on the aggregation of polymer chains in the solid state. Unsurprisingly, polymers which had the smaller 2-ethylhexyl chains attached to the pyrene units (PPEH-DTBT and PPEH-DTffBT) displayed lower molecular weights relative to polymers with larger 2-hexyldecyl substituents (PPHD-DTBT and PPHD-DTffBT). Despite this, the 2-ethylhexyl substituted polymers displayed narrower optical band gaps relative to their analogous 2-hexyldecyl substituted polymers. Of all polymers synthesised, PPEH-DTBT displayed the lowest optical band gap (1.76 eV) in the series. All polymers display degradation temperatures in excess of 300°C. Polymers with smaller alkyl chains on the pyrene units display shallower HOMO levels which could be due to increased intramolecular charge transfer between the donor and acceptor units. Preliminary investigations on bulk heterojunction solar cells with a device structure ITO/PEDOT:PSS/Polymer:PC70BM/Ca/Al were undertaken. Polymer/PC70BM blend ratios of 1/3 were used in these studies and have indicated that PPEH-DTBT displayed the highest efficiency with a PCE of 1.86 %

Inhibition of DDAH1, but not DDAH2, results in apoptosis of a human trophoblast cell line in response to TRAIL.

STUDY QUESTION: Does inhibition of dimethylarginine dimethylaminohydrolase (DDAH) increase the sensitivity of trophoblasts to TRAIL-induced apoptosis? SUMMARY ANSWER: Inhibition of DDAH1, but not DDAH2, increases the sensitivity of trophoblasts to TRAIL-induced apoptosis. WHAT IS KNOWN ALREADY: Successful human pregnancy is dependent on adequate trophoblast invasion and remodelling of the maternal spiral arteries. Increased trophoblast apoptosis is seen in pregnancies complicated by pre-eclampsia. The mechanism underlying this increase is unknown. We have previously shown that nitric oxide (NO) is involved in regulating trophoblast motility and invasion, and have also demonstrated an important role for NO in regulating trophoblast sensitivity to apoptotic stimuli. DDAH is an enzyme that metabolizes asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthesis, previously shown to be elevated in the plasma of pre-eclamptic mothers. STUDY DESIGN, SIZE, DURATION: This study used the human extravillous trophoblast-derived cell line SGHPL-4 cells. All experiments were performed at least three times. PARTICIPANTS/MATERIALS, SETTING, METHODS: The effect of DDAH on trophoblast apoptosis was examined using siRNA and time-lapse microscopy. Changes in the expression of DDAH were followed by PCR and western blot analysis. Receptor expression was followed by flow cytometry. MAIN RESULTS AND THE ROLE OF CHANCE: Inhibiting the expression of DDAH1, but not DDAH2, resulted in a significant increase in the sensitivity of the EVT cell line SGHPL-4 to tumour necrosis factor related apoptosis inducing ligand (TRAIL) induced apoptosis (P < 0.01). This response could be mimicked by the addition of Asymmetric Dimethylarginine (ADMA), an endogenous inhibitor of NO synthesis and the substrate for both isoforms of DDAH. We further showed that this increased sensitivity to apoptosis is accompanied by a significant increase in the expression of TRAIL receptor 2 (TR2; P < 0.05) but not TRAIL receptor 1 (TR1). LIMITATIONS, REASONS FOR CAUTION: This study was performed only in vitro using a well characterized trophoblast cell line, SGHPL-4, derived from first trimester extravillous trophoblasts. WIDER IMPLICATIONS OF THE FINDINGS: This study provides new insight into the role of the DDAH/ADMA pathway in the regulation of trophoblast function. Both dysregulation of DDAH and the accumulation of ADMA have been associated with the development of pre-eclampsia. This is the first study to implicate the DDAH/ADMA pathway as a mechanism that might underlie the poor trophoblast invasion seen in this common pregnancy disorder. STUDY FUNDING/COMPETING INTERESTS: B.A.L. was supported by a grant from Action Medical Research UK (SP4577). A.E.W. was supported by a grant from the Wellcome Trust (091550). There are no competing interests and the authors have no conflict interest to declare

A model of ant route navigation driven by scene familiarity

In this paper we propose a model of visually guided route navigation in ants that captures the known properties of real behaviour whilst retaining mechanistic simplicity and thus biological plausibility. For an ant, the coupling of movement and viewing direction means that a familiar view specifies a familiar direction of movement. Since the views experienced along a habitual route will be more familiar, route navigation can be re-cast as a search for familiar views. This search can be performed with a simple scanning routine, a behaviour that ants have been observed to perform. We test this proposed route navigation strategy in simulation, by learning a series of routes through visually cluttered environments consisting of objects that are only distinguishable as silhouettes against the sky. In the first instance we determine view familiarity by exhaustive comparison with the set of views experienced during training. In further experiments we train an artificial neural network to perform familiarity discrimination using the training views. Our results indicate that, not only is the approach successful, but also that the routes that are learnt show many of the characteristics of the routes of desert ants. As such, we believe the model represents the only detailed and complete model of insect route guidance to date. What is more, the model provides a general demonstration that visually guided routes can be produced with parsimonious mechanisms that do not specify when or what to learn, nor separate routes into sequences of waypoints

Spatial representation for navigation in animats

This article considers the problem of spatial representation for animat navigation systems. It is proposed that the global navigation task, or "wayfinding, " is best supported by multiple interacting subsystems, each of which builds its own partial representation of relevant world knowledge. Evidence from the study of animal navigation is reviewed to demonstrate that similar principles underlie the wayfinding behavior of animals, including humans. A simulated wayfinding system is described that embodies and illustrates several of the themes identified with animat navigation. This system constructs a network of partial models of the quantitative spatial relations between groups of salient landmarks. Navigation tasks are solved by propagating egocentric view information through this network, using a simple but effective heuristic to arbitrate between multiple solutions

Comparing Presenting Clinical Features in 48 Children With Microscopic Polyangiitis to 183 Children Who Have Granulomatosis With Polyangiitis (Wegener&apos;s) : an ARChiVe Cohort Study

OBJECTIVE: To uniquely classify children with microscopic polyangiitis (MPA), to describe their demographic characteristics, presenting clinical features, and initial treatments in comparison to patients with granulomatosis with polyangiitis (Wegener's) (GPA). METHODS: The European Medicines Agency (EMA) classification algorithm was applied by computation to categorical data from patients recruited to the ARChiVe (A Registry for Childhood Vasculitis: e-entry) cohort, with the data censored to November 2015. The EMA algorithm was used to uniquely distinguish children with MPA from children with GPA, whose diagnoses had been classified according to both adult- and pediatric-specific criteria. Descriptive statistics were used for comparisons. RESULTS: In total, 231 of 440 patients (64% female) fulfilled the classification criteria for either MPA (n\u2009=\u200948) or GPA (n\u2009=\u2009183). The median time to diagnosis was 1.6 months in the MPA group and 2.1 months in the GPA group (ranging to 39 and 73 months, respectively). Patients with MPA were significantly younger than those with GPA (median age 11 years versus 14 years). Constitutional features were equally common between the groups. In patients with MPA compared to those with GPA, pulmonary manifestations were less frequent (44% versus 74%) and less severe (primarily, hemorrhage, requirement for supplemental oxygen, and pulmonary failure). Renal pathologic features were frequently found in both groups (75% of patients with MPA versus 83% of patients with GPA) but tended toward greater severity in those with MPA (primarily, nephrotic-range proteinuria, requirement for dialysis, and end-stage renal disease). Airway/eye involvement was absent among patients with MPA, because these GPA-defining features preclude a diagnosis of MPA within the EMA algorithm. Similar proportions of patients with MPA and those with GPA received combination therapy with corticosteroids plus cyclophosphamide (69% and 78%, respectively) or both drugs in combination with plasmapheresis (19% and 22%, respectively). Other treatments administered, ranging in decreasing frequency from 13% to 3%, were rituximab, methotrexate, azathioprine, and mycophenolate mofetil. CONCLUSION: Younger age at disease onset and, perhaps, both gastrointestinal manifestations and more severe kidney disease seem to characterize the clinical profile in children with MPA compared to those with GPA. Delay in diagnosis suggests that recognition of these systemic vasculitides is suboptimal. Compared with adults, initial treatment regimens in children were comparable, but the complete reversal of female-to-male disease prevalence ratios is a provocative finding

An insect-inspired active vision approach for orientation estimation with panoramic images

Stürzl W, Möller R. An insect-inspired active vision approach for orientation estimation with panoramic images. In: Mira J, ed. Proc. IWINAC 07. Lecture Notes in Computer Science. Vol 4527. Berlin, Heidelberg: Springer; 2007: 61-70