Kramers-Kronig constrained variational analysis of optical spectra

A universal method of extraction of the complex dielectric function $\epsilon(\omega)=\epsilon_{1}(\omega)+i\epsilon_{2}(\omega)$ from experimentally accessible optical quantities is developed. The central idea is that $\epsilon_{2}(\omega)$ is parameterized independently at each node of a properly chosen anchor frequency mesh, while $\epsilon_{1}(\omega)$ is dynamically coupled to $\epsilon_{2}(\omega)$ by the Kramers-Kronig (KK) transformation. This approach can be regarded as a limiting case of the multi-oscillator fitting of spectra, when the number of oscillators is of the order of the number of experimental points. In the case of the normal-incidence reflectivity from a semi-infinite isotropic sample the new method gives essentially the same result as the conventional KK transformation of reflectivity. In contrast to the conventional approaches, the proposed technique is applicable, without readaptation, to virtually all types of linear-response optical measurements, or arbitrary combinations of measurements, such as reflectivity, transmission, ellipsometry {\it etc.}, done on different types of samples, including thin films and anisotropic crystals.Comment: 10 pages, 7 figure

Cloning whole bacterial genomes in yeast

Most microbes have not been cultured, and many of those that are cultivatable are difficult, dangerous or expensive to propagate or are genetically intractable. Routine cloning of large genome fractions or whole genomes from these organisms would significantly enhance their discovery and genetic and functional characterization. Here we report the cloning of whole bacterial genomes in the yeast Saccharomyces cerevisiae as single-DNA molecules. We cloned the genomes of Mycoplasma genitalium (0.6 Mb), M. pneumoniae (0.8 Mb) and M. mycoides subspecies capri (1.1 Mb) as yeast circular centromeric plasmids. These genomes appear to be stably maintained in a host that has efficient, well-established methods for DNA manipulation

The Global Burden of Alveolar Echinococcosis

Human alveolar echinococcosis (AE), caused by the larval stage of the fox tapeworm Echinococcus multilocularis, is amongst the world's most dangerous zoonoses. Transmission to humans is by consumption of parasite eggs which are excreted in the faeces of the definitive hosts: foxes and, increasingly, dogs. Transmission can be through contact with the definitive host or indirectly through contamination of food or possibly water with parasite eggs. We made an intensive search of English, Russian, Chinese and other language databases. We targeted data which could give country specific incidence or prevalence of disease and searched for data from every country we believed to be endemic for AE. We also used data from other sources (often unpublished). From this information we were able to make an estimate of the annual global incidence of disease and disease burden using standard techniques for calculation of DALYs. Our studies suggest that AE results in a median of 18,235 cases globally with a burden of 666,433 DALYs per annum. This is the first estimate of the global burden of AE both in terms of global incidence and DALYs and demonstrates the burden of AE is comparable to several diseases in the neglected tropical disease cluster

THE RELATIONSHIP BETWEEN INCOME INEQUALITY AND CITY SIZE - A GENERAL EQUILIBRIUM-MODEL OF AN OPEN SYSTEM OF CITIES APPROACH

A conclusion which emerges from studies of the factors affecting income inequality among cities is that many are connected through a number of different mechanisms with city size, The explanations are derived from partial equilibrium models of the labour market and ignore considerations associated with labour mobility among cities, To remedy this deficiency our paper employs a well developed general equilibrium model of an open system of cities to characterise the relationship between city size and income inequality that emerges, An outstanding conclusion derived is that, unlike existing explanations which provide justifications only for a unidirectional--positive or negative-relation between city size and income inequality, the general equilibrium model applies no restrictions on the direction of the relation, Additional restrictions are therefore needed to justify a positive or negative relation. For instance, if households with high income have relative preferences for non-traded goods, whose prices are shown to rise with city size, while households with low income have relative preferences for traded goods, inequality will rise with city size, Conversely, if households with low income have relative preferences for non-traded goods while high-income households have relative preferences for traded goods, income inequality will decline with city size, The model is employed to derive a few propositions regarding the direction of the relation under diverse conditions, These propositions provide plausible explanations for certain relations which may prove to be useful for testing the relevancy of our model, The explanations are more flexible than previous explanations since they can cope with a wider range of predictions, including a reversal of the relation, compatible with empirical observations

Israeli settlement in occupied territories and its impact on housing prices in Israel

The real price of housing in Israel rose 132 percent from 1959 through 1988. This paper investigates the factors standing behind the temporal movement of the real price of housing. Special emphasise is given to the role of government policies that encouraged settlement in occupied territories. A static model of the housing market is formulated and estimated, which takes into account the interrelation between the housing market in Israel proper and the emerging market in the occupied territories. In addition to confirming the role of demand shifters in accounting for the increase in real housing prices, it is found that settlement in occupied territories was an important moderating factor. According to our estimates, settlement in occupied territories accounts for a moderation of 1 percent in the annual rate of price appreciation during the Labor government, and 2.4 percent during the Likud government. These figures are in line with our expectations in view of the different policies pursued by the rival governments

Urban structure with two coexisting and almost completely segregated populations: The case of East and West Jerusalem

Polycentric population density functions are becoming increasingly popular among urban economists who claim that monocentric functions are inadequate for analyzing population distribution of contemporary, relatively dispersed urban areas. Unfortunately, none of the studies which appeared has been successful in generating a theoretical model amenable to straightforward empirical application. It is even unclear what the relationship is between a polycentric function and the individual functions derived for each center. In this paper we estimate monocentric and duocentric density functions using census tract data for Jerusalem. The somewhat simplified urban structure of this city, which contains two almost completely economically and politically segregated populations, each interacting with its separate central business district (CBD), appears to be advantageous in uncovering the relationships between the monocentric and duocentric functions. The findings of the analysis provide support for the duocentric formulation employed. Whereas the qualitative and quantitative results of the duocentric estimates are similar to those derived with the monocentric model, the best statistical fit of the data is obtained with the duocentric model. These findings enhance the credibility of the duocentric model, because compatibility is expected when dealing with two almost completely segregated populations. Further support is obtained when the model is estimated jointly with the location of the two CBDs. The estimates of the locations of the two CBDs are found to be extremely accurate. This is true for both the monocentric and duocentric regressions