Effects of closed immersion filtered water flow velocity on the ablation threshold of bisphenol A polycarbonate during excimer laser machining

A closed flowing thick film filtered water immersion technique ensures a controlled geometry for both the optical interfaces of the flowing liquid film and allows repeatable control of flow-rate during machining. This has the action of preventing splashing, ensures repeatable machining conditions and allows control of liquid flow velocity. To investigate the impact of this technique on ablation threshold, bisphenol A polycarbonate samples have been machined using KrF excimer laser radiation passing through a medium of filtered water flowing at a number of flow velocities, that are controllable by modifying the liquid flow rates. An average decrease in ablation threshold of 7.5% when using turbulent flow velocity regime closed thick film filtered water immersed ablation, compared to ablation using a similar beam in ambient air; however, the use of laminar flow velocities resulted in negligible differences between closed flowing thick film filtered water immersion and ambient air. Plotting the recorded threshold fluence achieved with varying flow velocity showed that an optimum flow velocity of 3.00 m/s existed which yeilded a minimum ablation threshold of 112 mJ/cm2. This is attributed to the distortion of the ablation plume effected by the flowing immersion fluid changing the ablation mechanism: at laminar flow velocities Bremsstrahlung attenuation decreases etch rate, at excessive flow velocities the plume is completely destroyed, removing the effect of plume etching. Laminar flow velocity regime ablation is limited by slow removal of debris causing a non-linear etch rate over ‘n’ pulses which is a result of debris produced by one pulse remaining suspended over the feature for the next pulse. The impact of closed thick film filtered water immersed ablation is dependant upon beam fluence: high fluence beams achieved greater etch efficiency at high flow velocities as the effect of Bremsstrahlung attenuation is removed by the action of the fluid on the plume; low fluences loose efficiency as the beam makes proportionally large fluence losses at it passes through the chamber window and immersion medium

"Hell is Empty, and All the Devils are Here": The Influence of Doctor Faustus on The Tempest

There are a number of analogous scenes and characters between Doctor Faustus and The Tempest that contribute to an argument for the influence of Marlowe's play upon Shakespeare's. Such an influence can have a profound effect on how we read The Tempest, specifically regarding how we perceive Prospero and Ariel.No embarg

Overcoming Information Asymmetries in Low-Income Lending: Lessons from the "Working Wheels" Program

This study analyzes the role of relationship lending in the automobile credit market among a population generally perceived to be high risk - and thereby 'unlendable'. Using a unique dataset from the Vermont Development Credit Union's "Working Wheels" low-income car loan program, we find that the strength of the relationship between creditor and higher risk borrowers significantly raises the probability of loan approval, and that such borrowers who receive loans are relatively creditworthy. Specifically, for applicants without credit scores, we find that -- in addition to income and debt ratio -- age and the nature of the established relationship with the lender significantly affect the probability of loan approval. By contrast, for applicants with credit scores, only income, debt ratio and the credit score are the significant determinants. In addition, despite the greater information asymmetry associated with applicants whose credit histories are unknown, we find no significant difference in delinquency rates between those with and without credit scores. In the current climate of welfare reform, we conclude that policymakers should consider programs that encourage welfare recipients to establish relationships with traditional financial institutions and establish more programs like "Working Wheels" that facilitate access to affordable credit for automobiles.low-income lending, relationship lending, information asymmetries, automobile loans, credit-rationing

Overcoming Information Asymmetries in Low-Income Lending: Lessons from the 'Working Wheels' Program

Without access to reliable transportation, the welfare-to-work transition for low-income households is nearly impossible, yet very little is known about the effectiveness of targeted loan programs designed to improve their access to credit. Since 1998, Vermont's TANF funds have been used to provide automobile loans to low-income residents through the "Working Wheels" program of the Vermont development Credit Union. In this paper, we take advantage of unique micro-level data on Working Wheels loan applications and loan performance to explore how such programs can cost-effectively provide car loans to those who are unable to obtain affordable loans elsewhere. Our results verify the importance of relationship lending, particularly among those without documented credit histories. In the presence of pronounced information asymmetries about credit history, our results justify a loan officer's increased trust in a client with whom the bank has had a stronger relationship; such clients, ceteris paribus, are less likely to default. We conclude that in the current climate of welfare reform, policymakers should consider programs that encourage welfare recipients to establish and maintain relationships with financial institutions in order to facilitate access to affordable credit and to minimize the risk of loan default.low-income lending, relationship lending, information asymmetries, automobile loans, credit-rationing, social capital

Parsing the Mind with Homer

How does one parse the mind? Do we categorize its functioning as mental or physical? Is it one big homogenous lump or a heterogeneous set of distinct abilities or mental faculties? Do we envision its workings to be like some kind of hydraulic mechanism or more like some kind of information processor? A large variety of possibilities have been offered over the centuries. Current models of the mind see it functioning like an information processor with numerous distinct modules carrying out individual tasks. Minds need to be excellent parsers, categorizers, and story tellers in order to get us by in whatever reality we find ourselves

Does Relationship Lending Still Matter in the Consumer Banking Sector? Evidence from Two Financial Service Organizations in Vermont

We use actual loan applications submitted to a community development credit union (CDCU) and a traditional community bank to examine the role of relationship lending in the automobile loan market. We first show that the community bank relies upon credit scoring, not relationship lending; low-income households with poor credit histories are very unlikely to receive car loans from this traditional bank. We then show that relationship lending is a critical factor in the loan decision at the CDCU; low-income households with strong ties to the institution are likely to receive loans, despite poor credit histories. We conclude that as consolidation, deregulation and technology move mainstream financial institutions away from relationship lending and toward credit scoring, CDCUs will occupy an increasingly critical niche for low-income households.

The response of ostracod faunal assemblages to hydrology, lake level, and carbon cycling in a Jamaican marl lake: a palaeolimnological investigation

Ostracod taxa from shallow freshwater lakes are sensitive to a range of limnological factors including temperature, hydrological habitat, lake level, and the distribution of aquatic plants. Ostracod assemblages preserved in Quaternary lake sediments can be used to reconstruct limnological change and are therefore potentially valuable palaeoenvironmental proxies. However, lack of autecological information about some taxa may limit the validity of such reconstructions. We use fossil ostracod assemblages recovered from radiocarbon-dated late Holocene sediments from Wallywash Great Pond, a small, shallow freshwater lake in southwestern Jamaica, to reconstruct limnological change over the past ∼ 1800 years. We circumvent ongoing taxonomic and ecological uncertainties associated with the identification of fossil ostracod taxa by drawing on observations of the ecology of ostracods found living in Jamaican water bodies. By combining this information with limnological data from the extant lake, and with sedimentological and isotopic data from the lake sediments, we show that a published interpretation of ostracod assemblages for the late Quaternary of Wallywash Great Pond is simplistic, at least for the late Holocene section of the sediment record. We conclude that changes in ostracod assemblages are linked to variations in the input of undersaturated groundwater to the northern part of the lake from which the core was recovered. These variations, which were driven by changes in the precipitation / evaporation ratio (effective moisture), also controlled sedimentation, with reduced effective moisture and a decline in undersaturated groundwater input favouring marl precipitation, whereas organic sediments are linked to increased effective moisture and enhanced groundwater input. Our findings suggest that the dramatic shifts in ostracod assemblages at this site are a complex response to changes in hydrology, sedimentology, and carbonate saturation rather than being a simple indicator of lake-level change. Combining ostracod assemblage data with the results of other palaeolimnological analyses also allows more detailed reconstructions to be made for this lake, and such a multiproxy approach is recommended for similar lakes elsewhere.</p

Construction and testing of a low-cost device for the collection of rainfall samples destined for stable isotope analysis

Oxygen- and hydrogen-isotope ratios in rainfall provide important hydroclimatic information, yet despite a global network of rainfall isotope measurements, significant geographical gaps exist in data coverage, with only three long-term stations spanning the southern African region. Project-based, ad hoc collections of rainfall for isotope analysis can improve this coverage. However, all rainfall samples that are destined for stable isotope analysis must be collected in such a way to avoid evaporation and resultant isotope fractionation. While such rainwater collectors are available commercially, both the product and shipping are prohibitively costly. We describe the construction of a simple rainfall collector using a design from the literature and materials that are readily available in South African hardware stores. Our rainwater collector can be constructed for the much lower cost of just under ZAR820 in comparison with the cost of ZAR9300 inclusive of shipping from commercial outlets (2022 prices). Our design modifications have the added advantage of portability, with the rainwater collector housed in a bucket with a handle. The device was tested by comparing its performance, in terms of evaporative water loss and isotopic fractionation, with that of an open bottle, using tap water in both cases. Testing confirmed that the collector prevented evaporation over a one-week period, indicating that it is suitable for weekly or more frequent sampling of rainfall. Although the design described was based on materials procured in South Africa, it could easily be adapted for construction elsewhere