497 research outputs found

    Sino-Soviet Dispute: An Analysis of the Clash of Ideology and National Interest

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    Political Scienc

    Optimization of Photocathode for Tandem-Dye Solar Cell

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    Tandem dye sensitized solar cells(DSSCs) is a modification of n-type DSSCs, and could be a new device for increasing the efficiency of solar cells by converting more of the solar spectrum than can be obtained by one photoelectrode alone. The solar device is composed by two electrodes which are sensitized with two different and complimentary dyes that collect lower energy photons on one electrode and higher energy photons on the other [1]. NiO oxide is used as p-type semiconductor, and the sensitizers is anchoring on it; under irradiation, the sensitizer is excited and decays by hole injection into the VB of the NiO, forming a charge separated state. A redox couple, in most cases an iodine/triiodide couple, reacts with the charge sensitizer to regenerate the fundamental state and transports the electron to the counter electrode. The Open-Circuit Photovoltage(Voc) is the difference between the potential of the redox couple and the NiO Fermi Level. The efficiency of tandem solar cells is limited by the p-type photocathode and the higher efficiency reached until now is 1.3% [2]. The most restriction in this case is the recombination process between the hole in the NiO to reduced dye, that limits photocurrent, and the recombination to electrolyte. So, in order to have an efficient device, the dye regeneration and the charge injection into NiO must be able to compete with recombination. In this research we test new sensitizers: one based on boron-dipyrromethene and a cationic acceptor dye for application in tandem DSSCs [3]; in particular we focused the attention on the optimization of the NiO p-DSSC. We also study the influence of co-adsorbents in order to limit the aggregation and the recombination process

    An Exploration of Fairness in the Assessment and Process of Student Group Work

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    This project was driven by a motivation to be as fair as possible in the assessment of students\u27 group work. Achieving fairness in assessment is a recurrent them in group project assessment literature (Nordberg, 2009). All authors of this report teach modules with group projects, and acknowledged that discrepancies often exist between a mark assigned to a group and an individual\u27s contribution. Our aims were to (a) collectively enhance our understanding of the issues that need to be considered when assessing a group work project and (b) collectively build our confidence in approaches chosen to overcome these challenges. The findings of a literature review on group work assessment informed the creation of a methodology to develop a toolkit which can be referred to when planning and setting group work assignments. An intermediary stage of this process was the development of an algorithm which incorporated user perspectives to assign associated values to assignment outputs and how they are assessed. This subjective user input, whether it is generated within a School, a subject matter or from a large sample of educators, can then be applied by associated users. An intended output of these potential processes is that the tailored toolkits can assist educators and/or programmes regardless of their teaching philosophy. Flash-cards were developed as a prototype of how the toolkit information can be visualised

    A predictive processing theory of sensorimotor contingencies: explaining the puzzle of perceptual presence and its absence in synesthesia

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    Normal perception involves experiencing objects within perceptual scenes as real, as existing in the world. This property of “perceptual presence” has motivated “sensorimotor theories” which understand perception to involve the mastery of sensorimotor contingencies. However, the mechanistic basis of sensorimotor contingencies and their mastery has remained unclear. Sensorimotor theory also struggles to explain instances of perception, such as synesthesia, that appear to lack perceptual presence and for which relevant sensorimotor contingencies are difficult to identify. On alternative “predictive processing” theories, perceptual content emerges from probabilistic inference on the external causes of sensory signals, however, this view has addressed neither the problem of perceptual presence nor synesthesia. Here, I describe a theory of predictive perception of sensorimotor contingencies which (1) accounts for perceptual presence in normal perception, as well as its absence in synesthesia, and (2) operationalizes the notion of sensorimotor contingencies and their mastery. The core idea is that generative models underlying perception incorporate explicitly counterfactual elements related to how sensory inputs would change on the basis of a broad repertoire of possible actions, even if those actions are not performed. These “counterfactually-rich” generative models encode sensorimotor contingencies related to repertoires of sensorimotor dependencies, with counterfactual richness determining the degree of perceptual presence associated with a stimulus. While the generative models underlying normal perception are typically counterfactually rich (reflecting a large repertoire of possible sensorimotor dependencies), those underlying synesthetic concurrents are hypothesized to be counterfactually poor. In addition to accounting for the phenomenology of synesthesia, the theory naturally accommodates phenomenological differences between a range of experiential states including dreaming, hallucination, and the like. It may also lead to a new view of the (in)determinacy of normal perception

    Basketball small-sided games: effects of varying formats and using successive bouts

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    This study compared athletes’ rate of perceived exertion (RPE) and the number of their technical-tactical actions in small-sided basketball games (SSG) played within the same relative area with adjusted bout durations in (a) varied game formats; and (b) in two successive bouts of different formats. Ten young female basketball players (14.3±1.3 years) played two bouts of five small-sided game (SSG) formats (1x1, 2x2, 3x3, 4x4, and 5x5). The number of technical-tactical actions per player per minute decreased from the smaller to the larger SSG format, and players’ RPE tended to be higher in larger compared to smaller formats. We concluded that the smaller basketball SSG formats increased players’ participation. In addition, adjustments of the relative playing area and bout duration seemed to decrease players’ effort. The use of two SSG bouts did impact the number of technical-tactical actions and RPE

    Ni Mg mixed metal oxides for p-type dye-sensitized solar cells

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    Mg Ni mixed metal oxide photocathodes have been prepared by a mixed NiCl2/MgCl2 sol-gel process. The MgO/NiO electrodes have been extensively characterized using physical and electrochemical methods. Dye-sensitized solar cells have been prepared from these films and the higher concentrations of MgO improved the photovoltage of these devices, however, there was a notable drop in photocurrent with increasing Mg2+. Charge extraction and XPS experiments revealed that the cause of this was a positive shift in the energy of the valence band which decreased the driving force for electron transfer from the NiO film to the dye and therefore the photocurrent. In addition, increasing concentrations of MgO increases the volume of pores between 0.500 to 0.050 μm, while reducing pore volumes in the mesopore range (less than 0.050 μm) and lowering BET surface area from approximately 41 down to 30 m2 g-1. A MgO concentration of 5% was found to strike a balance between the increased photovoltage and decreased photocurrent, possessing a BET surface area of 35 m2 g-1 and a large pore volume in both the meso and macropore range, which lead to a higher overall power conversion efficiency than NiO alone

    Perceptions of US adolescents and adults with sickle cell disease on their quality of care

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    Importance: Sickle cell disease (SCD) is the most common inherited red blood cell disorder in the United States, and previous studies have shown that individuals with SCD are affected by multiple health disparities, including stigmatization, inequities in funding, and worse health outcomes, which may preclude their ability to access quality health care. This needs assessment was performed as part of the Sickle Cell Disease Implementation Consortium (SCDIC) to assess barriers to care that may be faced by individuals with SCD. Objective: To assess the SCD-related medical care experience of adolescents and adults with SCD. Design, Setting, and Participants: This one-time survey study evaluated pain interference, quality of health care, and self-efficacy of 440 adults and adolescents (aged 15 to 50 years) with SCD of all genotypes and assessed how these variables were associated with their perceptions of outpatient and emergency department (ED) care. The surveys were administered once during office visits by trained study coordinators at 7 of 8 SCDIC sites in 2018. Results: The SCDIC sites did not report the number of individuals approached to participate in this study; thus, a response rate could not be calculated. In addition, respondents were not required to answer every question in the survey; thus, the response rate per question differed for each variable. Of 440 individuals with SCD, participants were primarily female (245 [55.7%]) and African American (428 [97.3%]) individuals, with a mean (SD) age of 27.8 (8.6) years. The majority of participants (306 of 435 [70.3%]) had hemoglobin SS or hemoglobin S β0-thalassemia. Most respondents (361 of 437 [82.6%]) reported access to nonacute (usual) SCD care, and the majority of respondents (382 of 413 [92.1%]) noted satisfaction with their usual care physician. Of 435 participants, 287 (66.0%) reported requiring an ED visit for acute pain in the previous year. Respondents were less pleased with their ED care than their usual care clinician, with approximately half (146 of 287 [50.9%]) being satisfied with or perceiving having adequate quality care in the ED. Participants also noted that when they experienced severe pain or clinician lack of empathy, this was associated with a negative quality of care. Age group was associated with ED satisfaction, with younger patients (\u3c19 vs 19-30 and 31-50 years) reporting better ED experiences. Conclusions and Relevance: These results suggested that a negative perception of care may be a barrier for patients seeking care. These findings underscore the necessity of implementation studies to improve access to quality care for this population, especially in the acute care setting

    Phage typing and clonal analysis of Salmonella Heidelberg strains isolated from animals and other sources from Minnesota (USA) and Germany

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    Salmonella Heidelberg isolates has become an emerging pathogen during the 80s in the United States (Martin et al., 1989). Approximately 60% of human cases reported to the CDC in 1995 were caused by only four serovars, including S. Enteridis (24,7%), S. Typhimurium (23,5%), S. Newport (6,2%) and S. Heidelberg (5,1%), (CDC, Salmonella surveillance) and were frequently isolated from chicken and pork (Sawari et al., 2001)

    Pancreas and islet cell transplantation

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    Currently, for the patient with type 1 diabetes, a definitive treatment without resorting to the use of exogenous insulin can be achieved only with pancreas or islet cell transplantation. These means of restoring β-cell mass can completely maintain essentially normal long-term glucose homeostasis, although the need for powerful immunosuppressive regimens limits their application to only a subgroup of adult patients. Apart from the shortage of donors that has limited all kinds of transplantation, however, the widespread use of β-cell replacement has been precluded until recently by the drawbacks associated with both organ and islet cell transplantation. Although the study of recurrence of diabetes has generated attention, the fundamental obstacle to pancreas and islet transplantation has been, and remains, the alloimmune response. With a better elucidation of the mechanisms of alloengraftment achieved during the last 3 years, the stage has been set for further advances

    From computers to cultivation: reconceptualizing evolutionary psychology.

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    Does evolutionary theorizing have a role in psychology? This is a more contentious issue than one might imagine, given that, as evolved creatures, the answer must surely be yes. The contested nature of evolutionary psychology lies not in our status as evolved beings, but in the extent to which evolutionary ideas add value to studies of human behavior, and the rigor with which these ideas are tested. This, in turn, is linked to the framework in which particular evolutionary ideas are situated. While the framing of the current research topic places the brain-as-computer metaphor in opposition to evolutionary psychology, the most prominent school of thought in this field (born out of cognitive psychology, and often known as the Santa Barbara school) is entirely wedded to the computational theory of mind as an explanatory framework. Its unique aspect is to argue that the mind consists of a large number of functionally specialized (i.e., domain-specific) computational mechanisms, or modules (the massive modularity hypothesis). Far from offering an alternative to, or an improvement on, the current perspective, we argue that evolutionary psychology is a mainstream computational theory, and that its arguments for domain-specificity often rest on shaky premises. We then go on to suggest that the various forms of e-cognition (i.e., embodied, embedded, enactive) represent a true alternative to standard computational approaches, with an emphasis on "cognitive integration" or the "extended mind hypothesis" in particular. We feel this offers the most promise for human psychology because it incorporates the social and historical processes that are crucial to human "mind-making" within an evolutionarily informed framework. In addition to linking to other research areas in psychology, this approach is more likely to form productive links to other disciplines within the social sciences, not least by encouraging a healthy pluralism in approach
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