Tuning Hole Transport Layer Using Urea for High‐Performance Perovskite Solar Cells

Interface engineering is critical to the development of highly efficient perovskite solar cells. Here, urea treatment of hole transport layer (e.g., poly(3,4‐ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS)) is reported to effectively tune its morphology, conductivity, and work function for improving the efficiency and stability of inverted MAPbI₃ perovskite solar cells (PSCs). This treatment has significantly increased MAPbI₃ photovoltaic performance to 18.8% for the urea treated PEDOT:PSS PSCs from 14.4% for pristine PEDOT:PSS devices. The use of urea controls phase separation between PEDOT and PSS segments, leading to the formation of a unique fiber‐shaped PEDOT:PSS film morphology with well‐organized charge transport pathways for improved conductivity from 0.2 S cm^?1 for pristine PEDOT:PSS to 12.75 S cm^?1 for 5 wt% urea treated PEDOT:PSS. The urea‐treatment also addresses a general challenge associated with the acidic nature of PEDOT:PSS, leading to a much improved ambient stability of PSCs. In addition, the device hysteresis is significantly minimized by optimizing the urea content in the treatment.     

Head tracked retroreflecting 3D display

In this paper, we describe a single‐user glasses‐free (autostereoscopic) 3D display where images from a pair of picoprojectors are projected on to a retroreflecting screen. Real images of the projector lenses formed at the viewer's eyes produce exit pupils that follow the eye positions by the projectors moving laterally under the control of a head tracker. This provides the viewer with a comfortable degree of head movement. The retroreflecting screen, display hardware, infrared head tracker, and means of stabilizing the image position on the screen are explained. The performance of the display in terms of crosstalk, resolution, image distortion, and other parameters is described. Finally, applications of this display type are suggested.     

Fluorescent proteins as markers in the plant secretory pathway

The use of fluorescent proteins and live cell imaging has greatly increased our knowledge of cell biology in recent years. Not only can these technologies be used to study protein trafficking under different conditions, but they have also been of use in elucidating the relationships between different organelles in a noninvasive manner. The use of multiple different fluorochromes allows the observation of interactions between organelles and between proteins, making this one of the fastest-developing and exciting fields at this time. In this review, we discuss the multitude of fluorescent markers that have been generated to study the plant secretory pathway. Although these markers have been used to solve many mysteries in this field, some areas that require further discussion remain.     

Localized content-based image retrieval

We define localized content-based image retrieval as a CBIR task where the user is only interested in a portion of the image, and the rest of the image is irrelevant. In this paper we present a localized CBIR system, Accio, that uses labeled images in conjunction with a multiple-instance learning algorithm to first identify the desired object and weight the features accordingly, and then to rank images in the database using a similarity measure that is based upon only the relevant portions of the image. A challenge for localized CBIR is how to represent the image to capture the content. We present and compare two novel image representations, which extend traditional segmentation-based and salient point-based techniques respectively, to capture content in a localized CBIR setting.     

Close to me: the effect of asymmetrical environments on spatial attention

Attention can be captured by distractors and can affect performance. To examine whether asymmetrical distractors, such as a wall, affect spatial attention, Experiment 1 required participants (n = 20) to determine the relative length of pre-bisected lines when a temporary barrier was placed close to the left or right sides of the display. Post-hoc tests showed that attention was drawn towards left, but not right, walls. Experiment 2 (n = 18) sought to increase this effect using a solid brick wall rather than a temporary barrier. Instead of strengthening the result, no effect of barrier was observed. A non-effect was also observed in Experiment 3 (n = 18) when participants moved a cursor to the line's middle. Finally, Experiment 4 (n = 26) showed that asymmetrical barriers had no effect on visual search. While the data showed some evidence that attention is distracted by walls placed to the left, this effect is weak and task-specific.

Practitioner Summary: The ability to monitor critical information on displays can be affected by asymmetrical distractors. In many workplaces, a display may be placed alongside a wall. This study explored whether a wall placed to the left/right affects spatial attention. A weak, task-specific, attraction effect was observed for walls on the left.     

Influence of aggregation inhibitors (verbenone and ipsidenol) on landing and attack behavior ofDendroctonus brevicomis (Coleoptera: Scolytidae)

The influence of the aggregation inhibitors verbenone and ipsdienol on the response of western pine beetle,Dendroctonus brevicomis, to attractive host trees was investigated. Paired ponderosa pine trees (Pinus ponderosa) were baited with aggregation semiochemicals to stimulate mass attack. One tree in each pair received an inhibitor treatment consisting of five sets of two verbenone and two ipsdienol dispensers spaced 1 m apart vertically along the tree bole. Beetle landing was monitored with sticky traps on the tree bole, and attack density was assessed from bark samples removed four or seven days after baiting. The inhibitor treatment resulted in a significant reduction of both the numbers of beetles landing on trees and the density of attacking beetles compared to control trees (without inhibitors). The ratios of beetle landing density to attacking density were not different between inhibitor-treated and control trees, nor were the vertical distributions of beetles landing or attacking, suggesting that beetle behavior was primarily influenced at a longer range, prior to landing on the tree. Although the application of verbenone and ipsdienol did not preventD. brevicomis from attacking baited trees, our results suggest that when applied to unattacked (and unbaited) trees, their effectiveness at reducing the attack pressure might allow trees having a certain amount of resistance to survive attack by pioneer beetles.     

The progressive party problem: Integer linear programming and constraint programming compared

Many discrete optimization problems can be formulated as either integer linear programming problems or constraint satisfaction problems. Although ILP methods appear to be more powerful, sometimes constraint programming can solve these problems more quickly. This paper describes a problem in which the difference in performance between the two approaches was particularly marked, since a solution could not be found using ILP.The problem arose in the context of organizing a progressive party at a yachting rally. Some yachts were to be designated hosts; the crews of the remaining yachts would then visit the hosts for six successive half-hour periods. A guest crew could not revisit the same host, and two guest crews could not meet more than once. Additional constraints were imposed by the capacities of the host yachts and the crew sizes of the guests.Integer linear programming formulations which included all the constraints resulted in very large models, and despite trying several different strategies, all attempts to find a solution failed. Constraint programming was tried instead and solved the problem very quickly, with a little manual assistance. Reasons for the success of constraint programming in this problem are identified and discussed.     

Studies of possible chemical emissions from PVC articles used in indoor applications and the effect on indoor air quality

Owing to their widespread use in interior applications, PVC products are frequently discussed in studies of indoor air quality. This paper reports results from the study of products in use and also products based on laboratory formulations that incorporate both unnaturally high and low levels of ingredients that could volatilize into the indoor air, thus giving a worst and best case scenario in terms of indoor emissions. Both PVC wallcovering and PVC flooring formulations have been studied, and laboratory produced samples have been subjected to gas chromatographic analysis to determine both the chemical species and the concentrations at which these can be emitted in typical interior applications. In all cases, including the worst ones, the level of these species in the indoor air is well below the permitted interior levels for the species concerned. These results, plus some outline of the concern over indoor health, are presented.     

The use of contingency management and motivational/skills-building therapy to treat young adults with marijuana dependence.

Marijuana-dependent young adults (N = 136), all referred by the criminal justice system, were randomized to 1 of 4 treatment conditions: a motivational/skills-building intervention (motivational enhancement therapy/cognitive-behavioral therapy; MET/CBT) plus incentives contingent on session attendance or submission of marijuana-free urine specimens (contingency management; CM), MET/CBT without CM, individual drug counseling (DC) plus CM, and DC without CM. There was a significant main effect of CM on treatment retention and marijuana-free urine specimens. Moreover, the combination of MET/CBT plus CM was significantly more effective than MET/CBT without CM or DC plus CM, which were in turn more effective than DC without CM for treatment attendance and percentage of marijuana-free urine specimens. Participants assigned to MET/CBT continued to reduce the frequency of their marijuana use through a 6-month follow-up. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electronic [re]constitution of groups: Group dynamics from face-to-face to an online setting

The authors work as online tutors for a BSc (Hons) physiotherapy programme at Coventry University in the United Kingdom. This paper represents a stage in our developing understanding, over a 3 year period, of the impact of group dynamics on online interaction among physiotherapy students engaged in sharing with their peers their first experiences of clinical practice. The literature exploring online interaction tends to situate meaning either in theories borrowed from conventional face-to-face interaction or on virtual interaction. Research focusing on ‘blended learning’ that combines face-to-face and online interaction is limited in terms of considering how group dynamics impact groups that are constituted and reconstituted in the two very different learning contexts. Using a case study approach, the authors consider how group dynamics change as groups move from face-to-face to online collaboration in pursuit of learning objectives. We characterize typical features of the cases and draw conclusions based on similarities and differences. Findings suggest that group learning is linked to group cohesion, which appears to be mediated by social and cognitive factors that students bring with them. Social presence appears vital to positive group dynamics and is a precursor to cognitive presence, which develops when groups rise above their desire to be sociable and supportive. Group dynamics, whether positive or negative, and their consequent impact on interaction appear to be relatively stable across contexts once the group scene is set through face-to-face interaction. Engagement and interaction of individual students, however, can alter when face-to-face interaction moves online.