Population genetics in the homothallic lichen-forming ascomycete Xanthoria parietina

The genetic diversity within and among populations of Xanthoria parietina was studied at the subspecific level with a fingerprinting technique (RAPD-PCR) applied to sterile cultured multispore isolates, each being derived from a single apothecium. Populations from coastal, rural and urban sites from NW, SW and central France and from NE Switzerland were investigated. Between 1 and 8 microsites of a few decimetres square, each comprising 13 to 27 thalli of X. parietina, were analysed per population. A total of 132 isolates from epiphytic and 3 isolates from epilithic specimens were investigated. Phenotypic variation was recorded among some of the thalli in the field and among sterile cultured isolates in the laboratory. A high diversity of genotypes was observed, even among thalli growing side by side in phenotypically homogenous populations. An average of 73·5 % polymorphism was found in all samples. As shown with Principal Coordinates Analysis (PCO), most of the genetic variation (90%) resided within, not among, populations. As X. parietina had previously been shown with molecular and fingerprinting techniques to be homothallic, the potential genetic background of this diversity is discussed. Intense genotype rather than gene (allele) flow seems to be an important element in X. parietina population

Highly efficient 3rd generation multi-junction solar cells using silicon heterojunction and perovskite tandem : prospective life cycle environmental impacts

In this study, the environmental impacts of monolithic silicon heterojunction organometallic perovskite tandem cells (SHJ-PSC) and single junction organometallic perovskite solar cells (PSC) are compared with the impacts of crystalline silicon based solar cells using a prospective life cycle assessment with a time horizon of 2025. This approach provides a result range depending on key parameters like efficiency, wafer thickness, kerf loss, lifetime, and degradation, which are appropriate for the comparison of these different solar cell types with different maturity levels. The life cycle environmental impacts of SHJ-PSC and PSC solar cells are similar or lower compared to conventional crystalline silicon solar cells, given comparable lifetimes, with the exception of mineral and fossil resource depletion. A PSC single-junction cell with 20% efficiency has to exceed a lifetime of 24 years with less than 3% degradation per year in order to be competitive with the crystalline silicon single-junction cells. If the installed PV capacity has to be maximised with only limited surface area available, the SHJ-PSC tandem is preferable to the PSC single-junction because their environmental impacts are similar, but the surface area requirement of SHJ-PSC tandems is only 70% or lower compared to PSC single-junction cells. The SHJ-PSC and PSC cells have to be embedded in proper encapsulation to maximise the stability of the PSC layer as well as handled and disposed of correctly to minimise the potential toxicity impacts of the heavy metals used in the PSC layer

Mentoring and the Dynamics of Affirmative Action

We analyze the long-term workforce composition when the quality of mentoring available to majority and minority juniors depends on their representation in the workforce. A workforce with ≥ 50% majority workers invariably converges to one where the majority is overrepresented relative to the population. To maximize welfare, persistent interventions, such as group-specific fellowships, are often needed, and the optimal workforce may include minority workers of lower innate talent than the marginal majority worker. We discuss the role of mentorship determinants, talent dispersion, the scope of short-term interventions, various policy instruments and contrast our results to the classic fairness narrative

Mentoring and the Dynamics of Affirmative Action

We study the evolution of labor force composition when mentoring is more effective within members of the same socio-demographic type. Typically, multiple steady states exist. Some completely exclude juniors of one type. Even a mixed steady state tends to over-represent the type that is dominant in the population. In contrast, the efficient labor force balances talent recruitment against mentoring frictions. It may even underrepresent the dominant type and typically calls for persistent government intervention. This contrasts with the public discourse around temporary affirmative action. We consider specific policy instruments and show that hiring quotas can induce equilibrium employment insecurity

Environmental benefits of a circular economy : connecting waste type and geographic proximity

Introduction: The aim of a circular economy is to transform waste into resources. There is a plethora of waste and by-products that remain unused in the traditional linear industrial system. However, transformation from a linear to a circular system is challenging, limited by several constraints such as the availability of information on the specific composition of the waste, the availability in time and space, the quantity of waste, as well as limited knowledge of the usability of such waste products. These challenges are exacerbated by the initial effort needed for implementation before an economy benefits from economic, ecological or societal improvements. Nevertheless, a circular economy generates less waste and consumes fewer resources, which in return makes it more profitable due to cost savings enabled by efficient resource use. The goal of the SHAREBOX project is the development of a platform for the facilitation of synergies within the industry to enable a more circular flow of resources within the European process industries. The project consortium has 15 partners including research organisations, SMEs and industrial partners as well as market actors and is part of the EU framework program Horizon 2020. Materials and Methods: The SHAREBOX platform is a database of available waste and resources required by companies, enabling the transformation of waste to resources by matching of two demands. The platform also serves as the first point of contact between different partners in a circular system. Furthermore, the platform enables the identification of new synergies overarching the different subsectors of the industries as well as optimal matching from the perspective of a circular economy. The key objectives are the facilitation of circular synergies through information and communications technology, the provision of information required to realise circular synergies within European industries and the identification of new circular synergies. Results and Discussion: The results of circular industry systems facilitated by the National Industrial Symbiosis Program (NISP) in the United Kingdom show a substantial reduction in the consumption of resources and generation of emissions compared to linear systems. Nevertheless, if there is a plethora of different types of waste, there is also a plethora of different synergies. This leads to different results for each type of waste that is transformed to a resource. Furthermore, the life cycle stage of transformation also has to be included. A transformation such as the reuse of polyethylene terephthalate (PET) can lead to emissions or require additional auxiliary materials as well as transportation. Therefore, the potential benefit will never be equal to the total impact of the primary input because of the transformation stage and the associated environmental impacts of collection and beneficiation. We analysed the implications of the transformation of different waste types to resources when industries are located in different geographic locations under consideration of the life cycle stage of transformation. Figure 2 shows the most significant results of the net benefit within the set of analysed waste types: the transformation of PET and concrete waste. Waste PET can be transported up to 10 000 km by lorry and still provide a net benefit regarding greenhouse gas emissions due to circular use. However, in case of concrete, the results are very different. A net benefit only occurs if the additional transport distance compared to primary concrete is less than 5 km. As a reference, the median of the transported distance of completed transformations within the NISP in the United Kingdom according to Jensen et al. is indicated with a black cross. About half of the 979 transformations within NISP were realised within a radius of 33 km and only one quarter of the synergies involved distances greater than 64 km. Conclusions: Transformation from linear to circular systems can substantially reduce total resource consumption as well as emissions of the whole value chain and therefore contribute to a greener economy. However, matching industries for transformations leading to the substitution of primary materials is still a major challenge. In addition, the environmental benefits of the reuse of resources is limited by the life cycle stage of the transformation as well as by additional transportation that may be required. The analysed set of types of waste shows a broad range of potential benefits. For some types of waste, the net benefits are still considerable after the subtraction of the additional impacts due to the life cycle stage of transformation as well as additional transport requirements. However, for selected types of waste, the net benefit tends to be negligible. The completeness of the scope will be crucial for the assessment and generalisations overarching different types of waste remain challenging

Efficient radiative transfer calculation and sensor performance requirements for the aerosol retrieval by airborne imaging spectroscopy

Detailed aerosol measurements in time and space are crucial to address open questions in climate research. Earth observation is a key instrument for that matter but it is biased by large uncertainties. Using airborne imaging spectroscopy, such as ESA's upcoming airborne Earth observing instrument APEX, allows determining the widely used aerosol optical depth (AOD) with unprecedented accuracy thanks to its high spatial and spectral resolution, optimal calibration and high signal-to-noise ratios (SNR). This study was carried out within the overall aim of developing such a tropospheric aerosol retrieval algorithm. Basic and efficient radiative transfer equations were applied to determine the sensor performance requirement and a sensitivity analysis in context of the aerosol retrieval. The AOD retrieval sensitivity requirement was chosen according to the demands of atmospheric correction processes. Therefore, a novel parameterization of the diffuse path-radiance was developed to simulate the atmospheric and surface effects on the signal at the sensor level. It was found for typical remote sensing conditions and a surface albedo of less than 30% that a SNR of circa 300 is sufficient to meet the AOD retrieval sensitivity requirement at 550nm. A surface albedo around 50% requires much more SNR, which makes the AOD retrieval very difficult. The retrieval performance is further analyzed throughout the visual spectral range for a changing solar geometry and different aerosol characteristics. As expected, the blue spectral region above dark surfaces and high aerosol loadings will provide the most accurate retrieval results. In general, the AOD retrieval feasibility could be proven for the analyzed cases for APEX under realistic simulated conditions