Characteristics of thermoplastic sensitivity due to thickness

Thermoplastic, as a relief image recording material, has several advantageous characteristics. All processing is dry, development is almost instantaneous and in situ, and the recorded image can be erased and reused. Theoretical studies have shown that the amount of relief image formed in a thermoplastic is a function of the thermoplastic thickness and frequency of input exposure. This thesis shows that this relationship is valid under a number of physical restraints. Results indicate that there is a thickness to input-signal-modulation interaction within the thermoplastic. With variable frequency sinusoids as the input, the physical structure of the relief fringes formed is optimized when the input modulation is decreased, but there is also an 88% decrease in diffraction efficiency. Therefore higher spatial frequencies can be obtained for the thinner thermoplastics if a decrease in diffraction efficiency can be tolerated

Coins in Context: Local Economy, Value and Practice on the East African Swahili Coast

Coinage occupies an unusual position in archaeological research. Thriving scholarship on numismatics and monetary history ensures that the objects themselves are well-studied, often seen as an indication of chronology and of stylistic and commercial links. Yet coins might also be analysed as artefacts, and explored as part of the symbolic world of material culture through which archaeologists understand meaning and value in past societies. Using a recently-excavated assemblage of medieval Kilwa-type coins from Songo Mnara on the East African Swahili coast, this article explores the multiple ways that value was ascribed and created through use, rejecting a simple dichotomy between substantive and formal value. Attention is given to the contexts of the coins, which enables a discussion of the relationship between power and the constitution of value, the circulation and use of coins among townspeople, and their use within ritual and commemorative activity

The Archaeology of Emptiness? Understanding Open Urban Spaces in the Medieval World

Using examples from medieval Europe and Africa, an approach to understanding urban open spaces is proposed. We argue that new digital and high-resolution methodologies, combined with interpretive frameworks which stress the affective capacities of the material world, call for a reappraisal of open spaces as places of disruption, creativity, and emergent urbanity. We advance an intensive approach to create a methodological basis on which to reimagine emptiness as a stimulus for interaction, applying Deleuze and Guattari’s concept of smooth/striated space. Key themes are the role of open spaces in the negotiation of power, their capacity to facilitate encounters, and their role as a resource from which distinctive forms of urbanity might emerge. The paper advocates for greater attention to be paid to open spaces in the study of medieval urbanism

Estimating Anesthesia Time Using the Medicare Claim: A Validation Study

INTRODUCTION: Procedure length is a fundamental variable associated with quality of care, though seldom studied on a large scale. The authors sought to estimate procedure length through information obtained in the anesthesia claim submitted to Medicare to validate this method for future studies. METHODS: The Obesity and Surgical Outcomes Study enlisted 47 hospitals located across New York, Texas, and Illinois to study patients undergoing hip, knee, colon, and thoracotomy procedures. A total of 15,914 charts were abstracted to determine body mass index and initial patient physiology. Included in this abstraction were induction, cut, close, and recovery room times. This chart information was merged to Medicare claims that included anesthesia Part B billing information. Correlations between chart times and claim times were analyzed, models developed, and median absolute differences in minutes calculated. RESULTS: Of the 15,914 eligible patients, there were 14,369 for whom both chart and claim times were available for analysis. For these 14,369, the Spearman correlation between chart and claim time was 0.94 (95% CI 0.94, 0.95), and the median absolute difference between chart and claim time was only 5 min (95% CI: 5.0, 5.5). The anesthesia claim can also be used to estimate surgical procedure length, with only a modest increase in error. CONCLUSION: The anesthesia bill found in Medicare claims provides an excellent source of information for studying surgery time on a vast scale throughout the United States. However, errors in both chart abstraction and anesthesia claims can occur. Care must be taken in the handling of outliers in these data

Inequality and violent crime: evidence from data on robbery and violent theft

This article argues that the link between income inequality and violent property crime might be spurious, complementing a similar argument in prior analysis by the author on the determinants of homicide. In contrast, Fajnzylber, Lederman & Loayza (1998; 2002a, b) provide seemingly strong and robust evidence that inequality causes a higher rate of both homicide and robbery/violent theft even after controlling for country-specific fixed effects. Our results suggest that inequality is not a statistically significant determinant, unless either country-specific effects are not controlled for or the sample is artificially restricted to a small number of countries. The reason why the link between inequality and violent property crime might be spurious is that income inequality is likely to be strongly correlated with country-specific fixed effects such as cultural differences. A high degree of inequality might be socially undesirable for any number of reasons, but that it causes violent crime is far from proven