Rationalising the Interaction ofTax and Social Security: PartI: Specific Problem Areas.

This paper considers options for addressing problems in the way the tax and social security systems interact.TAX POLICY ; SOCIAL SECURITY

Rationalising the Interaction of Tax and social Security: Part II: Fundamental Reform Options.

This paper considers more major structural reforms which could address such problems in a systematic manner, and allow the implementation of a designed set of effective tax rates (ETRs) for social security clients and taxpayers.TAX POLICY ; SOCIAL SECURITY

The interpretation of magnetic anomalies between Iceland and Scotland

The collection of data, and the results of a detailed magnetic survey on the crest of the Iceland-Faeroes Rise are described, A matrix method is developed to transform gravity anomalies to magnetic anomalies, and vice versa, to determine the ratio of magnetism to density in an equivalent layer, to solve for the angle of magnetisation of a body causing a magnetic anomaly and to separate magnetic anomalies caused by different types of source body. The data from the detailed survey area are interpreted as supporting the conclusions of previous authors that the crustal structure of the Iceland-Faeroes Rise is highly anomalous for an oceanic setting, and 16 similar to that of Iceland, with at least two magnetic layers which contain central intrusive complexes; granitic rocks may also be present. The matrix methods developed in the first part of this work are used to interpret gravity and magnetic data from a previous Durham survey on the Iceland-Faeroes Rise. Results indicate that the magnetic anomalies are controlled by seismic structure on NE - SW profiles, but include a component which is independent of seismic structure which is of greater significance on NW - SE profiles. The latter component is identified as magnetisation changes as a function of time. Magnetic and gravity anomalies from the Scottish Continental Shelf region are used to demonstrate further the scope of the matrix methods for combined analysis of gravity and magnetic anomalies

Morphological and dietary responses of chipmunks to a century of climate change.

Predicting how individual taxa will respond to climatic change is challenging, in part because the impacts of environmental conditions can vary markedly, even among closely related species. Studies of chipmunks (Tamias spp.) in Yosemite National Park provide an important opportunity to explore the reasons for this variation in response. While the alpine chipmunk (T. alpinus) has undergone a significant elevational range contraction over the past century, the congeneric and partially sympatric lodgepole chipmunk (T. speciosus) has not experienced an elevational range shift during this period. As a first step toward identifying the factors underlying this difference in response, we examined evidence for dietary changes and changes in cranial morphology in these species over the past century. Stable isotope analyses of fur samples from modern and historical museum specimens of these species collected at the same localities indicated that signatures of dietary change were more pronounced in T. alpinus, although diet breadth did not differ consistently between the study species. Morphometric analyses of crania from these specimens revealed significant changes in cranial shape for T. alpinus, with less pronounced changes in shape for T. speciosus; evidence of selection on skull morphology was detected for T. alpinus, but not for T. speciosus. These results are consistent with growing evidence that T. alpinus is generally more responsive to environmental change than T. speciosus, but emphasize the complex and often geographically variable nature of such responses. Accordingly, future studies that make use of the taxonomically and spatially integrative approach employed here may prove particularly informative regarding relationships between environmental conditions, range changes, and patterns of phenotypic variation