Shaped nozzles for cryogenic buffer gas beam sources

Cryogenic buffer gas beams are important sources of cold molecules. In this work we explore the use of a converging-diverging nozzle with a buffer-gas beam. We find that, under appropriate circumstances, the use of a nozzle can produce a beam with improved collimation, lower transverse temperatures, and higher fluxes per solid angle

Investigating the Drivers of Farm Diversification Among U.S. Fruit and Vegetable Operations

Diversification of an agricultural operation’s crop mix is considered an environmental and financial management strategy. Environmentally, crop diversification can stabilize the ecosystem via the introduction of biodiversity, allowing for more rapid response to physical and social changes. Economically, crop mix diversification can mitigate risk. Though there are environmental and economic benefits of crop diversification, little economic work has been conducted on crop diversification outside of the row crop industry. This study estimated how internal and external factors affect crop diversification among fruit and vegetable (FV) operations. External factors included access to markets and land; internal factors included farmer beliefs and access to information from extension and network sources. An OLS regression was conducted using data from 1532 farmers across 16 states in the United States. Endogeneity was addressed using an instrumental variable approach and a score endogeneity test indicated that endogeneity was not an issue. OLS results indicate that selling locally increases diversification, while reliance on other farmers for information decreases diversification. A conditional quantile analysis was conducted to reveal factors’ effects across different degrees of diversification. Quantile results indicate that selling locally, season extension technologies, and use of organic practices positively influence crop diversification across all levels of diversification. Receiving information from farmers negatively influences diversification for specialized farms, but positively influences diversification for highly diversified operations

A complex origin for the Kelso Dunes, Mojave National Preserve, California, USA: A case study using a simple geochemical method with global applications

The Kelso Dune field in southern California is intriguing because although it is of limited areal extent (~100 km2), it has a wide variety of dune forms and contains many active dunes (~40 km2), which is unusual in the Mojave Desert. Studies over the past eight decades have concluded that the dunes are derived primarily from a single source, Mojave River alluvium, under a dominant, westerly-to-northwesterly wind regime. The majority of these studies did not, however, present data to support the Mojave River as the only source.We conducted mineralogical and geochemical studies ofmost of the 14 geomorphically defined dune groups of the Kelso Dune field aswell as potential sand sources, alluvial sediments fromthe surrounding mountain ranges. Results indicate that sands in the nine western dune groups have K/Rb and K/Ba (primarily fromK-feldspar) compositions that are indistinguishable from Mojave River alluvium (westerly/northwesterly winds) and Budweiser Wash alluvium (southwesterly winds), permitting an interpretation of two sources. In contrast, sands from the five eastern dune groups have K/Rb and K/Ba values that indicate significant inputs from alluvial fan deposits of the Providence Mountains. This requires either rare winds from the east or southeast or, more likely, aeolian reworking of distal ProvidenceMountain fan sediments bywinds fromthewest, at a rate greater than input fromtheMojave River or otherwestern sources. The results indicate that even a small dune field can have a complex origin, either from seasonally varying winds or complex alluvial-fan-dune interaction. Application of K/Rb and K/Ba in Kfeldspar as a provenance indicator could be used in many of the world\u27s ergs or sand seas, where dune origins are still not well understood or are controversial. Four examples are given from Africa and the Middle East where such an approach could yield useful new information about dune sand provenance

Mineralogic variability of the Kelso Dunes, Mojave Desert, California derived from Thermal Infrared Multispectral Scanner (TIMS) data

Mineral identification and mapping of alluvial material using thermal infrared (TIR) remote sensing is extremely useful for tracking sediment transport, assessing the degree of weathering and locating sediment sources. As a result of the linear relation between a mineral's percentage in a given area (image pixel) and the depth of its diagnostic spectral features, TIR spectra can be deconvolved in order to ascertain mineralogic percentages. Typical complications such as vegetation, particle size and thermal shadowing are minimized upon examination of dunes. Actively saltating dunes contain little to no vegetation, are very well sorted and lack the thermal shadows that arise from rocky terrain. The primary focus of this work was to use the Kelso Dunes as a test location for an accuracy analysis of temperature/emissivity separation and linear unmixing algorithms. Accurate determination of ground temperature and component discrimination will become key products of future ASTER data. A decorrelation stretch of the TIMS image showed clear color variations within the active dunes. Samples collected from these color units were analyzed for mineralogy, grain size, and separated into endmembers. This analysis not only revealed that the dunes contained significant mineralogic variation, but were more immature (low quartz percentage) than previously reported. Unmixing of the TIMS data using the primary mineral endmembers produced unique variations within the dunes and may indicate near, rather than far, source locales for the dunes. The Kelso Dunes lie in the eastern Mojave Desert, California, approximately 95 km west of the Colorado River. The primary dune field is contained within a topographic basin bounded by the Providence, Granite Mountains, with the active region marked by three northeast trending linear ridges. Although active, the dunes appear to lie at an opposing regional wind boundary which produces little net movement of the crests. Previous studies have estimated the dunes range from 70% to 90% quartz mainly derived from a source 40 km to the west. The dune field is assumed to have formed in a much more arid climate than present, with the age of the deposit estimated at greater than 100,000 years

The costs and benefits of active case management and rehabilitation for musculoskeletal disorders

The burden of musculoskeletal disorders (MSDs) to employers and workplaces is significant; and the most important cost to employers and society is lost time from work. ‘Case management’ is a goal-oriented approach to keeping employees at work and facilitating an early return to work. There is good scientific evidence that case management methods are costeffective through reducing time off work and lost productivity, and reducing healthcare costs. There is even stronger evidence that best-practice rehabilitation approaches have the very important potential to significantly reduce the burden of long-term sickness absence due to MSDs. The combination of case management with suitable rehabilitation principles is currently being used effectively in multiple settings throughout the UK, and there is growth within the case management sector. Current providers vary widely in quality and experience. There is limited professional regulation, although localised standards of practice have recently become available. Many of the factors influencing the adoption of cost-effective case management and rehabilitation approaches rest with employers, and funders/commissioners of healthcare. It may be easier to integrate these practices into large and medium-sized workplaces, but there is no reason why the same principles cannot be applied to small businesses and the self-employed. It appears to be very timely for the distribution of information to employers and other key players about how effective case management and suitable rehabilitation approaches can be, and how applicable they are to UK settings. To this end, an integrated model specific to the UK has been developed. An evidence-based model for managing those with MSDs was developed that is widely applicable to all types of industry and business in the UK. It describes the principles to apply in order to integrate case management and rehabilitation with the workplace. It was derived from high quality scientific studies, and research conducted into views on the applicability and effectiveness within the UK. It is recommended that HSE distribute guidance based on this model

Adiabatic ring opening in tethered naphthalene and anthracene cycloadducts

The cycloadducts of tethered naphthalene and anthracene derivatives undergo photochemical ring opening to an electronically excited product with adiabatic yields up to 90%