Collimated dual species oven source and its characterisation via spatially resolved fluorescence spectroscopy

We describe the design, construction and characterisation of a collimated, dual-species oven source for generating intense beams of lithium and caesium in UHV environments. Our design produces full beam overlap for the two species. Using an aligned microtube array the FWHM of the output beam is restricted to ~ 75 milliradians, with an estimated axial brightness of 3.6x10[superscript]14 atoms s[superscript]-1 sr[superscript]-1 for Li and 7.4x10[superscript]15 atoms s[superscript]-1 sr[superscript]-1 for Cs. We measure the properties of the output beam using a spatially-resolved fluorescence technique, which allows for the extraction of additional information not accessible without spatial resolution

A recursive semantics for defeasible reasoning

One of the most striking characteristics of human beings is their ability to function successfully in complex environments about which they know very little. In light of our pervasive ignorance, we cannot get around in the world just reasoning deductively from our prior beliefs together with new perceptual input. As our conclusions are not guaranteed to be true, we must countenance the possibility that new information will lead us to change our minds, withdrawing previously adopted beliefs. In this sense, our reasoning is “defeasible”. The question arises how defeasible reasoning works, or ought to work. In particular we need rules governing what a cognizer ought to believe given a set of interacting arguments some of which defeat others. That is what is called a “semantics” for defeasible reasoning, and this chapter will propose a new semantics that avoids certain clear counter-examples to all existing semantics. 1. Reasoning in the Face of Pervasive Ignorance One of the most striking characteristics of human beings is their ability to function successfully in complex environments about which they know very little. Reflect on how little you really kno

UNHCR Activities in the Republic of Belarus in 1992 - 1995 (Andrey Selivanov)

Раздел - "Международные отношения"UNHCR's presence in Belarus, as indeed in all post-soviet countries, was established in the beginning of the1990s. For various reasons, the USSR had remained outside the international refugee protection system. As UNHCR began to develop a strategy for its involvement in the post-Soviet region in the spring of 1992, this U N refugee agency sent its first fact-finding mission to Belarus. In general, the UNHCR's activities in Belarus in 1992—1995 indicated the efforts in creating organizational and technical potential of the state to settle the problems of refugees and rendering aid to refugees themselves through the framework of the Belarusian Red Cross despite the fact that this society itself acted through the U N Office in the Republic of Belarus. Belarus was given sufficient attention to by the UNHCR which resulted in the expansion of contacts and eventually in opening in 1995 of the UNHCR Liason Office in the Republic of Belarus

The structure of idealization in biological theories: the case of the Wright-Fisher model.

In this paper we present a new framework of idealization in biology. We characterize idealizations as a network of counterfactual and hypothetical conditionals that can exhibit different “degrees of contingency”. We use this idea to say that, in departing more or less from the actual world, idealizations can serve numerous epistemic, methodological or heuristic purposes within scientific research. We defend that, in part, this structure explains why idealizations, despite being deformations of reality, are so successful in scientific practice. For illustrative purposes, we provide an example from population genetics, the Wright-Fisher Mode