Solar-grade silicon prepared by carbothermic reduction of silica

An advanced carbothermic reduction (ACR) process was developed to produce solar grade (SC) silicon from high purity silica and carbon. Preparation of starting materials and operation of the arc furnace to product high purity silicon is described. Solar cells prepared from single crystal SG-Si had efficiencies of up to 12.3% practically identical to cells made from electronic grade silicon. The ACR process is not in the pilot stage for further evaluation

Nature’s contributions to people and the Sustainable Development Goals in Nepal

Nature's contributions to people (NCPs) underpin the attainment of the Sustainable Development Goals (SDGs) but are declining globally. It is therefore critical to identify the drivers of changes in NCPs, and to understand how and where NCPs can contribute towards the achievement of the SDGs. By integrating the conceptual framework of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBESs) and the SDGs, we can obtain a better understanding of how changes in the state of NCPs support or hinder attainment of the SDGs, and how changes in NCPs are driven by development interventions. We conducted a systematic synthesis of the literature to determine the state of research on NCPs, trends in NCPs and their drivers, and the contribution of NCPs towards achieving the SDGs in Nepal, a low-income and highly biodiverse country. We found that NCPs contributed positively towards the achievement of 12 SDGs. However, NCPs were reported to be declining across Nepal, ultimately undermining Nepal's ability to achieve SDG targets. The major direct drivers of decline were land-use change, over-exploitation, and climate change. These direct drivers were linked to conventional development interventions, including agricultural expansion and the construction of road and energy infrastructure. However, some interventions, such as community forestry and protected areas, increased the supply of NCPs. Better integration of Indigenous knowledge and local practices was also reported to be effective in improving the provision of NCPs and contributing to improving livelihoods at local scales. We identified opportunities for further research in NCPs, particularly in increasing geographical representativeness and improving our understanding of non-material NCPs. Our approach of combining the IPBES conceptual framework and the SDGs enabled us to more comprehensively identify how progress towards the SDGs are mediated by NCPs and provides actionable guidelines for how to take more integrative measures to achieve the SDGs in Nepal and countries facing similar development challenges

Self similar Barkhausen noise in magnetic domain wall motion

A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/\omega^\alpha$, where $\alpha\approx 1.5$ can be estimated from the critical exponents for interface depinning in random media.Comment: 7 pages, RevTex. To appear in Phys. Rev. Let

Divide or Commit – Revisiting the Role of Cell Cycle Regulators in Adult Hippocampal Neurogenesis

The adult dentate gyrus continuously generates new neurons that endow the brain with increased plasticity, helping to cope with changing environmental and cognitive demands. The process leading to the birth of new neurons spans several precursor stages and is the result of a coordinated series of fate decisions, which are tightly controlled by extrinsic signals. Many of these signals act through modulation of cell cycle (CC) components, not only to drive proliferation, but also for linage commitment and differentiation. In this review, we provide a comprehensive overview on key CC components and regulators, with emphasis on G1 phase, and analyze their specific functions in precursor cells of the adult hippocampus. We explore their role for balancing quiescence versus self-renewal, which is essential to maintain a lifelong pool of neural stem cells while producing new neurons “on demand.” Finally, we discuss available evidence and controversies on the impact of CC/G1 length on proliferation versus differentiation decisions

Mass diffusion measurements in liquid crystals by a novel optical method

Binary mass diffusion measurements have been performed in fluid media doped with photochromic dye molecules. A periodic concentration of tagged molecules is created by illuminating the sample with a fringe intensity pattern. The photo induced change of refractive index and/or absorption of the dye molecules creates an optical grating which is observed through Bragg diffraction of an auxiliary laser beam. When the flash excitation is switched off. this grating will relax since photoexcited molecules will diffuse into nonphotoexcited zones and vice versa. The main advantages of this method are that: (1) the duration of the experiment is strongly reduced compared to classical tracer methods since diffusion lengths. defined by the fringe spacing. are small (1-100 fLm); (2) the possibility of studying anisotropic diffusion is readily available; and (3) small sample volumes are required. Results are reported on the diffusion of methyl red in a homogeneously aligned sample of MBBA. In the nematic phase. the diffusion is faster along the local optical axis than perpendicular, the anisotropic ratio DU / Dl being 1.6±O.l at 22 "C. in good agreement with previous tracer data. The temperature dependence yields an activation energy of 5.8±O.7 kcallmole for DII and 6.0±O.8 kcallmole for D 1 • In the isotropic phase. the activation energy is found to be \O± 1.5 kcallmole

Comparison between overlap and twisted mass fermions towards the chiral limit

We compare overlap fermions, which are chirally invariant, and Wilson twisted mass fermions in the approach to the chiral limit. Our quenched simulations reveal that with both formulations of lattice fermions pion masses of O(250 MeV) can be reached in practical simulations. Our comparison is done at a fixed lattice spacing a=0.123 fm. Several quantities are measured, such as hadron masses and pseudoscalar decay constants.Comment: Lattice2004(chiral

A multi‐methods approach for assessing how conserving biodiversity interacts with other sustainable development goals in Nepal

Achieving the sustainable development goals (SDGs) requires a context-specific understanding of how actions to achieve one goal interact with others. We analyzed statistical data, and conducted online surveys and interviews with conservation professionals to understand how terrestrial conservation goals (SDG 15: Life on land) influence and are influenced by other goals in Nepal. Our findings suggest that SDG 15 synergized with economic growth (SDG 8), gender equality (SDG 5), water access (SDG 6), sustainable production and consumption (SDG 12), and climate action (SDG 13), but traded off with food security (SDG 2), energy access (SDG 7), poverty alleviation (SDG 1), and infrastructure development (SDG 9). Increased multi-sectoral collaboration between conservation and development stakeholders is urgently needed to address the negative impacts of other goals on SDG 15. Additionally, conservation measures in Nepal can benefit from being more people-focused, participatory, and contextualized to mitigate negative impacts on socioeconomic goals