Solar Cell Light Trapping beyond the Ray Optic Limit

In 1982, Yablonovitch proposed a thermodynamic limit on light trapping within homogeneous semiconductor slabs, which implied a minimum thickness needed to fully absorb the solar spectrum. However, this limit is valid for geometrical optics but not for a new generation of subwavelength solar absorbers such as ultrathin or inhomogeneously structured cells, wire-based cells, photonic crystal-based cells, and plasmonic cells. Here we show that the key to exceeding the conventional ray optic or so-called ergodic light trapping limit is in designing an elevated local density of optical states (LDOS) for the absorber. Moreover, for any semiconductor we show that it is always possible to exceed the ray optic light trapping limit and use these principles to design a number of new solar absorbers with the key feature of having an elevated LDOS within the absorbing region of the device, opening new avenues for solar cell design and cost reduction

Light trapping beyond the 4n^2 limit in thin waveguides

We describe a method for determining the maximum absorption enhancement in thin film waveguides based on optical dispersion relations. For thin film structures that support one, well-confined guided mode, we find that the absorption enhancement can surpass the traditional limit of 4n^2 when the propagation constant is large and/or the modal group velocity is small compared to the bulk value. We use this relationship as a guide to predicting structures that can exceed the 4n^2 light trapping limit, such as plasmonic and slot waveguides. Finally, we calculate the overall absorption for both single and multimode waveguides, and show examples of absorption enhancements in excess of 4n^2 for both cases

Role of Schizosaccharomyces pombe RecQ homolog recombination and checkpoint genes in UV Damage tolerance

The cellular responses to DNA damage are complex and include direct DNA repair pathways that remove the damage and indirect damage responses which allow cells to survive DNA damage that has not been, or cannot be, removed. We have identified the gene mutated in the rad12.502 strain as a Schizosaccharomyces pombe recQ homolog. The same gene (designated rqh1) is also mutated in the hus2.22 mutant. We show that Rqh1 is involved in a DNA damage survival mechanism which prevents cell death when UV-induced DNA damage cannot be removed. This pathway also requires the correct functioning of the recombination machinery and the six checkpoint tad gene products plus the Cds1 kinase. Our data suggest that Rqh1 operates during S phase as part of a mechanism which prevents DNA damage causing cell lethality. This process may involve the bypass of DNA damage sites by the replication fork. Finally, in contrast with the reported literature, we do not find that rqh1 (rad12) mutant cells are defective in UV dimer endonuclease activity

The Richard commission and the financing of devolved government : the economics of devolution in Wales: Briefing No. 8

If the Barnett formula is rigorously applied to determine the budget of the Welsh Assembly Government, this will ultimately adversely affect the economy of Wales by limiting the growth in aggregate demand. This effect is reinforced now that population weights determining rises in expenditure in Wales (and Scotland and Northern Ireland) are regularly up-dated. There is some controversy in Wales about whether some form of needs-assessment exercise would favour Wales relative to its current position. What is clear is that the outcome of a rigorous, long term application of the Barnett formula would be a share of UK public expenditures in Wales (and Scotland and Northern Ireland) that was almost certainly below the level that would be dictated by any conventional understanding of 'needs'. The impact of the tax-varying power favoured by the Richard Commission is ambiguous, with the direction of effects dependent on the reaction of the current labour force and potential migrants. If workers insist on full compensation for loss of income to tax through a rise in gross wages a tax rise would lead to an economic contraction. However, if workers value the additional public services financed by the tax rise as equal to their loss of disposable income, this effect can be avoided. Much in other words would depend on how the proceeds of the tax rise were spen

The challenge of valuing ecosystem services that have no material benefits

Since the Millennium Ecosystem Assessment, ecosystem service science has made much progress in framing core concepts and approaches, but there is still debate around the notion of cultural services, and a growing consensus that ecosystem use and ecosystem service use should be clearly differentiated. Part of the debate resides in the fact that the most significant sources of conflict around natural resource management arise from the multiple managements (uses) of ecosystems, rather than from the multiple uses of ecosystem services. If the ecosystem approach or the ecosystem service paradigm are to be implemented at national levels, there is an urgent need to disentangle what are often semantic issues, revise the notion of cultural services, and more broadly, practically define the less tangible ecosystem services on which we depend. This is a critical step to identifying suitable ways to manage trade-offs and promote adaptive management. Here we briefly review the problems associated with defining and quantifying cultural ecosystem services and suggest there could be merit in discarding this term for the simpler non-material ecosystem services. We also discuss the challenges in valuing the invaluable, and suggest that if we are to keep ecosystem service definition focused on the beneficiary, we need to further classify these challenging services, for example by differentiating services to individuals from services to communities. Also, we suggest that focussing on ecosystem service change rather than simply service delivery, and identifying common boundaries relevant for both people and ecosystems, would help meet some of these challenges

Plants used to treat diabetes in Sri Lankan Siddha Medicine - an ethnopharmacological review of historical and modern sources

INTRODUCTION AND BACKGROUND: In recent decades diabetes mellitus has become a considerable health problem in countries like Sri Lanka and results in an increasing economic burden hampering the social and economic development of these countries. About 60 to 70 % of the rural population in Sri Lanka rely on indigenous medicinal systems as their main source for primary health care. Siddha (Tamil) Medicine is one of the four Sri Lankan traditional medicinal systems and it is practised mostly in the eastern and northern provinces of Sri Lanka where the majority of Tamils reside. AIM: The foundation of this study is a documentation of plant species recorded in historical and modern Sri Lankan Siddha Medical documents used to treat diabetes. Based on the systematic documentation and analysis of Siddha concepts about diabetes and its signs and preparations used to treat diabetes in Sri Lankan Siddha Medicine, the plant species included in these preparations (excluding globally or very widely used, very well studied species) were evaluated in terms of the current state-of-the-art about these species' pharmacology and effectiveness in order to lay a foundation for their further development. METHOD: Historic and modern Sri Lankan university texts books in Tamil were used as sources for information on diabetes Siddha concepts and antidiabetic Sri Lankan Siddha Medicine preparations. Information on the known antidiabetic effects of extracts and compounds obtained from these species were used in order to assess the current state of the art of these species. RESULTS AND DISCUSSION: Information of ingredients, preparation methods, amount of ingredients used, and dosages of 60 antidiabetic Sri Lankan Siddha Medicine preparations were obtained. Animal parts including marine organisms, inorganic substances, and plants are the three types of ingredients used. Overall 171 plant species in 73 families were documented. Senna auriculata (L.) Roxb. (Fabaceae) was identified as the most frequently cited species. Globally distributed and very well studied plants were excluded in the pharmacological and clinical literature review which includes 123 plant species. The majority (48 %) of the plant species reviewed were studied up to in vivo level as the current maximum level of scientific evidence available. Followed by 41 % of species have not been studied for antidiabetic activities or did not show antidiabetic activity. Moreover, 6 % and 5 % were studied up to in vitro and in clinical levels, respectively. The majority of the species were studied only in the models that represent type 1 diabetes. CONCLUSION: This is the first study systematically assessing the importance of preparations and plants used in antidiabetic Sri Lankan Siddha Medicine preparations. Antidiabetic plants are a crucial health care resource in Sri Lankan Siddha Medicine. This study also identified a wide range of methodological problems in the studies conducted so far. More and better type 2 diabetes models should be employed in future studies. This comprehensive review creates the basis for a more systematic study of these local resources

Exploring preferences for place of death with terminally ill patients: qualitative study of experiences of general practitioners and community nurses in England

Objective To explore the experiences and perceptions of general practitioners and community nurses in discussing preferences for place of death with terminally ill patients. Design Qualitative study using semistructured interviews and thematic analysis. Participants 17 general practitioners and 19 nurses (16 district nurses, three clinical nurse specialists). Setting 15 general practices participating in the Gold Standards Framework for palliative care from three areas in central England with differing socio-geography. Practices were selected on the basis of size and level of adoption of the standards framework. Results All interviewees bar one had experience of discussing preferred place of death with terminally ill patients. They reported that preferences for place of death frequently changed over time and were often ill defined or poorly formed in patients’ minds. Preferences were often described as being co-created in discussion with the patient or, conversely, inferred by the health professional without direct questioning or receiving a definitive answer from the patient. This inherent uncertainty challenged the practicability, usefulness, and value of recording a definitive preference. The extent to which the assessment of enabling such preferences can be used as a proxy for the effectiveness of palliative care delivery is also limited by this uncertainty. Generally, interviewees did not find discussing preferred place of death an easy area of practice, unless the patient broached the subject or led the discussions. Conclusions Further research is needed to enable development of appropriate training and support for primary care professionals. Better understanding of the importance of place of death to patients and their carers is also needed

The Effect of Nitrogen Rates and Plant Density on Grain Yield Components and Persistence in Intermediate Wheatgrass (\u3ci\u3eThinopyrum intermedium\u3c/i\u3e) and Mountain Rye (\u3ci\u3eSecale strictum\u3c/i\u3e)

Intermediate wheatgrass (IWG; Thinopyrum intermedium) and Mountain Rye (Mtn Rye; Secale strictum) have potential for release as dual-purpose (grazing and grain production) perennial grains in Australia due to their superior longevity compared to hybrid perennial wheats. Initially developed as perennial forage grasses, few management guidelines exist to inform agronomic practices to maximise grain yields and profitability in Australian environments. An experiment was established in 2020 to examine the effect of plant density and nitrogen rates on grain yield components. The experiment compared the two species (IWG, Mtn Rye) sown at three plant densities (50, 100 and 200 plants/m2) with three nitrogen rates (0, 100, 200 kg/ha N). Overall, in the first year of production, Mtn Rye had higher grain yields than Kernza although yield decreased with increasing N rates. With further selection for floret fertility and seed size, Mtn Rye could prove a successful candidate for a perennial grain crop in Australia