A metallurgical route to solar-grade silicon

The aim of the process is to produce silicon for crystallization into ingots that can be sliced to wafers for processing into photovoltaic cells. If the potential purity can be realized, the silicon will also be applicable for ribbon pulling techniques where the purification during crystallization is negligible. The process consists of several steps: selection and purification of raw materials, carbothermic reduction of silica, ladle treatment, casting, crushing, leaching, and melting. The leaching step is crucial for high purity, and the obtainable purity is determined by the solidification before leaching. The most difficult specifications to fulfill are the low contents of boron, phosphorus, and carbon. Boron and phosphorus can be excluded from the raw materials, but the carbothermic reduction will unavoidably saturate the silicon with carbon at high temperature. During cooling carbon will precipitate as silicon carbide crystals, which will be harmful in solar cells. The cost of this solar silicon will depend strongly on the scale of production. It is as yet premature to give exact figures, but with a scale of some thousand tons per year, the cost will only be a few times the cost of ordinary metallurgical silicon

Anal incontinence after vaginal delivery or cesarean section.

INTRODUCTION: Uncertainties remain as to whether cesarean section is protective for short and long term development of anal incontinence. Our aim was to explore whether women who had only delivered vaginally were at greater risk of anal incontinence compared to nulliparous women and women who had undergone caesarean sections only. MATERIAL AND METHODS: Background information, medical history and data on anal incontinence (defined as fecal or flatus incontinence weekly or more) reported by women participating in a large population-based health survey in Norway (HUNT 3) during the period October 2006-June 2008, was collected and linked to data from the Medical Birth Registry of Norway. Anal incontinence prevalence was calculated and multivariable logistic regression analyses were applied. RESULTS: Mean age amongst the 12.567 women was 49.9 years. Age and educational level were similar in women with caesarean sections only and those with vaginal delivery and obstetric anal sphincter injuries (OASIS). Nulliparas and women with vaginal delivery and no OASIS were older and had higher educational achievements. One in four women with OASIS reported anal incontinence compared to one in six amongst the other women(p<.001). Age, educational level, diarrhea, constipation, birthweight and OASIS increased the risk of anal incontinence in all women. Parity was associated with anal incontinence in parous women only. No differences were found for fecal urgency. CONCLUSIONS: Women with vaginal deliveries complicated by OASIS were at increased risk of anal incontinence. However, no increased risk of anal incontinence was found in nulliparous women or women with cesarean sections only or vaginal deliveries not complicated by OASIS

A quantum mechanical model of the upper bounds of the cascading contribution to the second hyperpolarizability

Microscopic cascading of second-order nonlinearities between two molecules has been proposed to yield an enhanced third-order molecular nonlinear-optical response. In this contribution, we investigate the two-molecule cascaded second hyperpolarizability and show that it will never exceed the fundamental limit of a single molecule with the same number of electrons as the two-molecule system. We show the apparent divergence behavior of the cascading contribution to the second hyperpolarizability vanishes when properly taking into account the intermolecular interactions. Although cascading can never lead to a larger nonlinear-optical response than a single molecule, it provides alternative molecular design configurations for creating materials with large third-order susceptibilities that may be difficult to design into a single molecule.Comment: 13 pages, 9 figures, 1 tabl

Cooperative Behavior in the Ultimatum Game and Prisoner's Dilemma Depends on Players' Contributions.

Economic games such as the Ultimatum Game (UG) and Prisoner's Dilemma (PD) are widely used paradigms for studying fairness and cooperation. Monetary versions of these games involve two players splitting an arbitrary sum of money. In real life, however, people's propensity to engage in cooperative behavior depends on their effort and contribution; factors that are well known to affect perceptions of fairness. We therefore sought to explore the impact of relative monetary contributions by players in the UG and PD. Adapted computerized UG and PD games, in which relative contributions from each player were manipulated, were administered to 200 participants aged 18-50 years old (50% female). We found that players' contribution had large effects on cooperative behavior. Specifically, cooperation was greater amongst participants when their opponent had contributed more to joint earnings. This was manifested as higher acceptance rates and higher offers in the UG; and fewer defects in the PD compared to when the participant contributed more. Interestingly, equal contributions elicited the greatest sensitivity to fairness in the UG, and least frequent defection in the PD. Acceptance rates correlated positively with anxiety and sex differences were found in defection behavior. This study highlights the feasibility of computerized games to assess cooperative behavior and the importance of considering cooperation within the context of effortful contribution

Agency and intentionality-dependent experiences of moral emotions

Moral emotions are thought to influence moral behaviour by providing a driving force to do good and to avoid doing bad. In this study we examined moral emotions; specifically, guilt, shame, annoyance and feeling “bad” from two different perspectives in a moral scenario; the agent and the victim whilst manipulating the intentionality of the harm; intentional and unintentional. Two hundred participants completed a moral emotions task, which utilised cartoons to depict everyday moral scenarios. As expected, we found that self-blaming emotions such as shame and guilt were much more frequent when taking on the perspective of the agent whilst annoyance was more frequent from the victim perspective. Feeling bad, however, was not agency-specific. Notably, when the harm was intentional, we observed significantly greater shame ratings from the perspective of the agent compared to when the harm was unintentional. In addition, we also found clear gender differences and further observed correlations between moral emotions and personality variables such as psychoticism and neuroticism

The operationalisation of sustainability: Sustainable aquaculture production as defined by certification schemes

Sustainability certification has become an increasingly important feature in aquaculture production, leading to a multitude of schemes with various criteria. However, the large number of schemes and the complexity of the standards creates confusion with respect to which sustainability objectives are targeted. As a result, what is meant by ‘sustainability’ is unclear. In this paper, we examine the operationalisation of the concept from the vantage point of the certifying authorities, who devise standards and grant or withhold certification of compliance. We map the criteria of eight widely-used certification schemes using the four domains of the Wheel of Sustainability, a reference model designed to encompass a comprehensive understanding of sustainability. We show that, overall, the sustainability certifications have an overwhelming focus on environmental and governance indicators, and only display scattered attempts at addressing cultural and economic issues. The strong focus on governance indicators is, to a large degree, due to their role in implementing and legitimising the environmental indicators. The strong bias implies that these certification schemes predominantly focus on the environmental domain and do not address sustainability as a whole, nor do they complement each other. Sustainability is by definition and by necessity a comprehensive concept, but if the cultural and economic issues are to be addressed in aquaculture, the scope of certification schemes must be expanded. The Wheel of Sustainability can serve as a valid lexicon and asset to guide such efforts.publishedVersio

Associations among nutrient concentration, silage fermentation products, in vivo organic matter digestibility, rumen fermentation and in vitro methane yield in 78 grass silages

Grass-clover silage constitutes a large part of ruminant diets in Northern and Western Europe, but the impact of silage quality on methane (CH4) production is largely unknown. This study was conducted to identify the quality attributes of grass silage associated with variation in CH4 yield. We expected that silage nutrient concentrations and silage fermentation products would affect CH4 yield, and that these factors could be used to predict the methanogenic potential of the si-lages. Round bales (n = 78) of grass and grass-clover silage from 37 farms in Norway were sampled, incubated, and screened for in vitro CH4 yield, i.e. CH4 production expressed on the basis of incubated organic matter (CH4-OM) and digestible OM (CH4-dOM) using sheep. Concentration of indigestible neutral detergent fiber (iNDF) was quantified using the in situ technique. The data were subjected to correlation and principal component analyses. Stepwise multiple regression was used to model methanogenic potential of silages. Among all investigated silage composition variables, neutral detergent fiber (aNDFom) and water-soluble carbohydrate (WSC) concentra-tions obtained the greatest correlations to CH4-OM (r =-0.63 and r = 0.57, respectively, P < 0.001), while concentration of iNDF negatively correlated with CH4-OM (r =-0.48, P < 0.001). In vivo organic matter digestibility (OMD) and concentration of ammonia-N (NH3-N) in silages were also correlated to CH4-OM (r = 0.44 and r =-0.32, P < 0.001 and P < 0.01, respectively). The stepwise regression using CH4-OM as response variable included aNDFom, WSC, iNDF, silage propionic acid and pH in descending order. The stepwise regression using CH4-dOM as response variable included WSC, aNDFom and iNDF in descending order. Among in vitro rumen short chain fatty acids (SCFA), molar proportion of butyrate was the most prominent in increasing CH4-OM and CH4-dOM (r = 0.23 and r = 0.36, P < 0.05 and P < 0.01, respectively), while molar proportion of propionate was the most prominent SCFA in reducing CH4-OM and CH4-dOM (r =-0.23 and r =-0.26, respectively, P < 0.05). Regression models that account for silage quality attributes can be used to predict CH4 yield from silages with a coefficient of determination (R-2) between 0.33 (CH4-dOM) and 0.65 (CH4-OM). In conclusion, concentration of WSC increased in vitro CH4-OM and CH4-dOM, while concentration of aNDFom and iNDF decreased CH4-OM and CH4-dOM in grass silages

High-Precision Inversion of Dynamic Radiography Using Hydrodynamic Features

Radiography is often used to probe complex, evolving density fields in dynamic systems and in so doing gain insight into the underlying physics. This technique has been used in numerous fields including materials science, shock physics, inertial confinement fusion, and other national security applications. In many of these applications, however, complications resulting from noise, scatter, complex beam dynamics, etc. prevent the reconstruction of density from being accurate enough to identify the underlying physics with sufficient confidence. As such, density reconstruction from static/dynamic radiography has typically been limited to identifying discontinuous features such as cracks and voids in a number of these applications. In this work, we propose a fundamentally new approach to reconstructing density from a temporal sequence of radiographic images. Using only the robust features identifiable in radiographs, we combine them with the underlying hydrodynamic equations of motion using a machine learning approach, namely, conditional generative adversarial networks (cGAN), to determine the density fields from a dynamic sequence of radiographs. Next, we seek to further enhance the hydrodynamic consistency of the ML-based density reconstruction through a process of parameter estimation and projection onto a hydrodynamic manifold. In this context, we note that the distance from the hydrodynamic manifold given by the training data to the test data in the parameter space considered both serves as a diagnostic of the robustness of the predictions and serves to augment the training database, with the expectation that the latter will further reduce future density reconstruction errors. Finally, we demonstrate the ability of this method to outperform a traditional radiographic reconstruction in capturing allowable hydrodynamic paths even when relatively small amounts of scatter are present.Comment: Submitted to Optics Expres