Mineralogical appraisal and beneficiation tests on some industrial minerals from Zambia

In March 1990, a visit to Zambia was made by D A Briggs of the Mineralogy and Petrology Group on behalf of the British Geological Survey/Overseas Development Administration project "Minerals for Development". The visit, which was described in Technical Report No. WG/90/15R, aimed to establish contact with the Geological Survey Department and other organisations concerned with minerals in Zambia to offer assistance in the field of mineral resource development. This primarily involved discussions with Mr N J Money and Mr J G G Tether, respectively Director and Deputy Director of the Geological Survey . department and their colleagues. The Ministry of Mines and the Mineral Exploration Department (Minex) of the Zambia Industrial and Mining Corporation and other bodies were also involved in the discussions

Enabling a High Throughput Real Time Data Pipeline for a Large Radio Telescope Array with GPUs

The Murchison Widefield Array (MWA) is a next-generation radio telescope currently under construction in the remote Western Australia Outback. Raw data will be generated continuously at 5GiB/s, grouped into 8s cadences. This high throughput motivates the development of on-site, real time processing and reduction in preference to archiving, transport and off-line processing. Each batch of 8s data must be completely reduced before the next batch arrives. Maintaining real time operation will require a sustained performance of around 2.5TFLOP/s (including convolutions, FFTs, interpolations and matrix multiplications). We describe a scalable heterogeneous computing pipeline implementation, exploiting both the high computing density and FLOP-per-Watt ratio of modern GPUs. The architecture is highly parallel within and across nodes, with all major processing elements performed by GPUs. Necessary scatter-gather operations along the pipeline are loosely synchronized between the nodes hosting the GPUs. The MWA will be a frontier scientific instrument and a pathfinder for planned peta- and exascale facilities.Comment: Version accepted by Comp. Phys. Com

The Beagle landing site in Isidis Planitia

The Mars probe Beagle 2 will land in Isidis Planitia. This region satisfies the engineering constraints and has evidence for particularly volatile-rich subsoil. Isidis provides a suitable place for the lander to search for H2O and organic matter

Worst case and probabilistic analysis of the 2-Opt algorithm for the TSP

2-Opt is probably the most basic local search heuristic for the TSP. This heuristic achieves amazingly good results on “real world” Euclidean instances both with respect to running time and approximation ratio. There are numerous experimental studies on the performance of 2-Opt. However, the theoretical knowledge about this heuristic is still very limited. Not even its worst case running time on 2-dimensional Euclidean instances was known so far. We clarify this issue by presenting, for every p∈N , a family of L p instances on which 2-Opt can take an exponential number of steps. Previous probabilistic analyses were restricted to instances in which n points are placed uniformly at random in the unit square [0,1]2, where it was shown that the expected number of steps is bounded by O~(n10) for Euclidean instances. We consider a more advanced model of probabilistic instances in which the points can be placed independently according to general distributions on [0,1] d , for an arbitrary d≥2. In particular, we allow different distributions for different points. We study the expected number of local improvements in terms of the number n of points and the maximal density ϕ of the probability distributions. We show an upper bound on the expected length of any 2-Opt improvement path of O~(n4+1/3⋅ϕ8/3) . When starting with an initial tour computed by an insertion heuristic, the upper bound on the expected number of steps improves even to O~(n4+1/3−1/d⋅ϕ8/3) . If the distances are measured according to the Manhattan metric, then the expected number of steps is bounded by O~(n4−1/d⋅ϕ) . In addition, we prove an upper bound of O(ϕ√d) on the expected approximation factor with respect to all L p metrics. Let us remark that our probabilistic analysis covers as special cases the uniform input model with ϕ=1 and a smoothed analysis with Gaussian perturbations of standard deviation σ with ϕ∼1/σ d

Differential metabolism of deoxyribonucleosides by leukaemic T cells of immature and mature phenotype

Experimental evidence has indicated that T lymphoblasts are more sensitive to deoxynucleoside toxicity than are B lymphoblasts. These data have led to the use of purine enzyme inhibitors as selective chemotherapeutic drugs in the treatment of T cell malignancies ranging from T cell acute lymphoblastic leukaemia to cutaneous T cell lymphomas. We have compared the toxicities of 2′-deoxyadenosine, 2′-deoxyguanosine, and thymidine for T cell lines derived from patients with T cell acute lymphoblastic leukaemia with those for mature T cell lines derived from patients with cutaneous T cell leukaemia/lymphoma. We have found that both deoxynucleosides are far less toxic to the mature T cell lies than to T lymphoblasts and that the mature cells accumulate much lower amounts of dATP and dGTP when exposed to deoxyadenosine and deoxyguanosine, respectively. Similar studies performed on peripheral blood cells from patients with T cell leukaemias of mature phenotype and on peripheral blood T cells demonstrate similar low amounts of deoxynucleotide accumulation. Measurements of the activities of several purine metabolizing enzymes that participate in deoxynucleoside phosphorylation or degradation do not reveal differences which would explain the toxicity of deoxynucleosides for immature, as compared to mature, T cells. We conclude that deoxynucleoside metabolism in leukaemic T cells varies with their degree of differentiation. These observations may be relevant to the design of chemotherapeutic regimes for T cell malignancies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72479/1/j.1365-2141.1985.tb04067.x.pd

Partisan Views of the Economy

In this paper it is argued that political parties may have incentives to adopt a partisan view on the working of the economic system. Our approach is based on a dynamical spatial voting model in which political parties are policy oriented. This model revolves around two interrelated issues x and y. The policy maker sets x directly. There exist two views on the relationship between x and y. Model uncertainty confronts policy makers with the problem of the selection of a model to base their actions on. We show that if voters have imperfect information about the working of the economic system that model selection contains a strategic element. Policy makers are inclined to adopt a view on the working of the economic system which fits in with their preferences. There is no inherent logic that places monetarists to the right of New Economists. They have different models of economic mechanism, but they need not have different political values. A conservative can be a Keynesian and a liberal a monetarist. These combinations are in fact surprisingly rare. James Tobin, 1974,The New Economics One Decade Older, p. 62. I am greatly indebted to Peter Broer, Ben Heydra, Jos Jansen and Wilko Letterie for many helpful suggestions. Furthermore, I would like to thank an anonymous referee for his comments

Cassini multi-instrument assessment of Saturn's polar cap boundary

We present the first systematic investigation of the polar cap boundary in Saturn's high-latitude magnetosphere through a multi-instrument assessment of various Cassini in situ data sets gathered between 2006 and 2009. We identify 48 polar cap crossings where the polar cap boundary can be clearly observed in the step in upper cutoff of auroral hiss emissions from the plasma wave data, a sudden increase in electron density, an anisotropy of energetic electrons along the magnetic field, and an increase in incidence of higher-energy electrons from the low-energy electron spectrometer measurements as we move equatorward from the pole. We determine the average level of coincidence of the polar cap boundary identified in the various in situ data sets to be 0.34° ± 0.05° colatitude. The average location of the boundary in the southern (northern) hemisphere is found to be at 15.6° (13.3°) colatitude. In both hemispheres we identify a consistent equatorward offset between the poleward edge of the auroral upward directed field-aligned current region of ~1.5–1.8° colatitude to the corresponding polar cap boundary. We identify atypical observations in the boundary region, including observations of approximately hourly periodicities in the auroral hiss emissions close to the pole. We suggest that the position of the southern polar cap boundary is somewhat ordered by the southern planetary period oscillation phase but that it cannot account for the boundary's full latitudinal variability. We find no clear evidence of any ordering of the northern polar cap boundary location with the northern planetary period magnetic field oscillation phase

Inflation and Brane Gases

We investigate a new way of realizing a period of cosmological inflation in the context of brane gas cosmology. It is argued that a gas of co-dimension one branes, out of thermal equilibrium with the rest of the matter, has an equation of state which can - after stabilization of the dilaton - lead to power-law inflation of the bulk. The most promising implementation of this mechanism might be in Type IIB superstring theory, with inflation of the three large spatial dimensions triggered by ``stabilized embedded 2-branes''. Possible applications and problems with this proposal are discussed.Comment: 7 pages, uses REVTeX, version to appear in Phys. Rev.

Association between Reimbursement Incentives and Physician Practice in Oncology: A Systematic Review

Importance: Significant controversy exists regarding whether physicians factor personal financial considerations into their clinical decision making. Within oncology, several reimbursement policies may incentivize physicians to increase health care use. Objective: To evaluate whether the financial incentives presented by oncology reimbursement policies affect physician practice patterns. Evidence Review: Studies evaluating an association between reimbursement incentives and changes in reimbursement policy on oncology care delivery were reviewed. Articles were identified systematically by searching PubMed/MEDLINE, Web of Science, Proquest Health Management, Econlit, and Business Source Premier. English-language articles focused on the US health care system that made empirical estimates of the association between a measurement of physician reimbursement/compensation and a measurement of delivery of cancer treatment services were included. The Risk of Bias in Non-Randomized Studies of Interventions tool was used to assess risk of bias. There were no date restrictions on the publications, and literature searches were finalized on February 14, 2018. Findings: Eighteen studies were included. All were observational cohort studies, and most had a moderate risk of bias. Heterogeneity of reimbursement policies and outcomes precluded meta-analysis; therefore, a qualitative synthesis was performed. Most studies (15 of 18 [83%]) reported an association between reimbursement and care delivery consistent with physician responsiveness to financial incentives, although such an association was not identified in all studies. Findings consistently suggested that self-referral arrangements may increase use of radiotherapy and that profitability of systemic anticancer agents may affect physicians' choice of drug. Findings were less conclusive as to whether profitability of systemic anticancer therapy affects the decision of whether to use any systemic therapy. Conclusions and Relevance: To date, this study is the first systematic review of reimbursement policy and clinical care delivery in oncology. The findings suggest that some oncologists may, in certain circumstances, alter treatment recommendations based on personal revenue considerations. An implication of this finding is that value-based reimbursement policies may be a useful tool to better align physician incentives with patient need and increase the value of oncology care