Does Advice Help to Prove Propositional Tautologies?

One of the starting points of propositional proof complexity is the seminal paper by Cook and Reckhow [6], where they defined propositional proof systems as poly-time computable functions which have all propositional tautologies as their range. Motivated by provability consequences in bounded arithmetic, Cook and Krajíček [5] have recently started the investigation of proof systems which are computed by poly-time functions using advice. While this yields a more powerful model, it is also less directly applicable in practice. In this note we investigate the question whether the usage of advice in propositional proof systems can be simplified or even eliminated. While in principle, the advice can be very complex, we show that proof systems with logarithmic advice are also computable in poly-time with access to a sparse NP-oracle. In addition, we show that if advice is ”not very helpful” for proving tautologies, then there exists an optimal propositional proof system without advice. In our main result, we prove that advice can be transferred from the proof to the formula, leading to an easier computational model. We obtain this result by employing a recent technique by Buhrman and Hitchcock [4]

The impacts of new A8 migration in Leeds

New arrivals from Eastern Europe have made regular headlines in the popular press in recent times, not only for the unprecedented magnitude of the flows involved, but also for their impacts – positive and negative – on regions and localities up and down the country. This paper reports on a recently completed research project aimed at finding out more about A8 migrants in Leeds

Feasibility study for locating archaeological village sites by satellite remote sensing techniques

There are no author-identified significant results in this report

The Role of Lactose Tolerance in Pre-Colonial Development

This paper establishes a link between natural selection since the Neolithic Revolution and economic conditions in the pre-colonial era. The ability to digest milk, or to be lactose tolerant, is conferred by a gene variant, which is unequally distributed across the Old World. Digesting milk conferred qualitative and quantitative advantages to early farmers's diets, which ultimately, led to differences in the carrying capacities of respective countries. It is shown through a number of specifications that country level variation in the frequency of the ability to consume milk is positively and significantly related to population densities in 1500 CE; specifically, a one standard deviation in- crease in the frequency of lactose tolerant individuals (24% points) is associated with roughly a 60% increase in pre-colonial population densities. This relationship remains while controlling for agricultural transition dates, other measures of genetic distance, and a wide array of environmental controls. Additionally, the basis for the relation- ship between dairying and population density is confirmed with the use of instrumental variables estimation.

Multiple Myeloma : an update on disease biology and therapy

Multiple myeloma is a malignancy of immunoglobulin producing plasma cells. Clinical features include bone pain due to lytic bone lesions or pathological fractures, anemia, symptomatic hypercalcemia, renal insufficiency, recurrent infections and amyloidosis. In the last few years, there have been considerable advances in the understanding of the biology of this disease. While multiple myeloma is biologically diverse, several oncogenes are activated in this illness. In addition, the role of the bone marrow microenvironment to support the growth and survival of the malignant cells has been well described. In this review, we discuss recent developments in the molecular pathogenesis of myeloma. These recent observations are being translated into novel therapeutic approaches that target both the tumor cell as well as the stroma. Current therapeutic strategies are discussed.peer-reviewe

A Noise Investigation of Tunnel-Diode Microwave Amplifiers

An analysis and derivation of the noise figure of a tunnel-diode microwave amplifier are presented. The agreement between the measured noise figure and the theoretical results is an indirect check on the existence of full shot noise in germanium tunnel diodes at microwave frequencies. The limiting noise temperature of the amplifier is eI0R/2k, and can be approached by using diodes with small (RC) products in which the extreme overcoupling (load mismatch) and high gain can be achieved simultaneously

Testing a Simplified Version of Einstein's Equations for Numerical Relativity

Solving dynamical problems in general relativity requires the full machinery of numerical relativity. Wilson has proposed a simpler but approximate scheme for systems near equilibrium, like binary neutron stars. We test the scheme on isolated, rapidly rotating, relativistic stars. Since these objects are in equilibrium, it is crucial that the approximation work well if we are to believe its predictions for more complicated systems like binaries. Our results are very encouraging.Comment: 9 pages (RevTeX 3.0 with 6 uuencoded figures), CRSR-107