An experimental comparison of a genetic algorithm and a hill-climber for term selection

Purpose – The term selection problem for selecting query terms in information filtering and routing has been investigated using hill-climbers of various kinds, largely through the Okapi experiments in the TREC series of conferences. Although these are simple deterministic approaches which examine the effect of changing the weight of one term at a time, they have been shown to improve the retrieval effectiveness of filtering queries in these TREC experiments. Hill-climbers are, however, likely to get trapped in local optima, and the use of more sophisticated local search techniques for this problem that attempt to break out of these optima are worth investigating. To this end, we apply a genetic algorithm (GA) to the same problem. Design/Methodology/Approach – We use a standard TREC test collection from the TREC-8 filtering track, recording mean average precision and recall measures to allow comparison between the hillclimber and GA algorithms. We also vary elements of the GA, such as probability of a word being included, probability of mutation and population size in order to measure the effect of these variables. Different strategies such as Elitist and Non-Elitist methods are used, as well as Roulette Wheel and Rank selection GA algorithms. Findings – The results of tests suggest that both techniques are, on average, better than the baseline, but the implemented GA does not match the overall performance of a hill-climber. The Rank selection algorithm does better on average than the Roulette Wheel algorithm. There is no evidence in this study that varying word inclusion probability, mutation probability or Elitist method make much difference to the overall results. Small population sizes do not appear to be as effective as larger population sizes. Research limitations/implications – The evidence provided here would suggest that being stuck in a local optima for the term selection optimization problem does not appear to be detrimental to the overall success of the hill-climber. The evidence from term rank order would appear to provide extra useful evidence which hill-climbers can use efficiently and effectively to narrow the search space. Originality/Value – The paper represents the first attempt to compare hill-climbers with GAs on a problem of this type

Underuse of coronary revascularization procedures in patients considered appropriate candidates for revascularization.

Background: Ratings by an expert panel of the appropriateness of treatments may offer better guidance for clinical practice than the variable decisions of individual clinicians, yet there have been no prospective studies of clinical outcomes. We compared the clinical outcomes of patients treated medically after angiography with those of patients who underwent revascularization, within groups defined by ratings of the degree of appropriateness of revascularization in varying clinical circumstances.Methods: This was a prospective study of consecutive patients undergoing coronary angiography at three London hospitals. Before patients were recruited, a nine-member expert panel rated the appropriateness of percutaneous transluminal coronary angioplasty (PTCA) and coronary-artery bypass grafting (CABG) on a nine-point scale (with 1 denoting highly inappropriate and 9 denoting highly appropriate) for specific clinical indications. These ratings were then applied to a population of patients with coronary artery disease. However, the patients were treated without regard to the ratings. A total of 2552 patients were followed for a median of 30 months after angiography.Results: Of 908 patients with indications for which PTCA was rated appropriate (score, 7 to 9), 34 percent were treated medically; these patients were more likely to have angina at follow-up than those who underwent PTCA (odds ratio, 1.97; 95 percent confidence interval, 1.29 to 3.00). Of 1353 patients with indications for which CABG was considered appropriate, 26 percent were treated medically; they were more likely than those who underwent CABG to die or have a nonfatal myocardial infarction - the composite primary outcome (hazard ratio, 4.08; 95 percent confidence interval, 2.82 to 5.93) - and to have angina (odds ratio, 3.03; 95 percent confidence interval, 2.08 to 4.42). Furthermore, there was a graded relation between rating and outcome over the entire scale of appropriateness (P for linear trend = 0.002).Conclusions: On the basis of the ratings of the expert panel, we identified substantial underuse of coronary revascularization among patients who were considered appropriate candidates for these procedures. Underuse was associated with adverse clinical outcomes. (N Engl J Med 2001;344:645-54.) Copyright (C) 2001 Massachusetts Medical Society

Uracil content of 16S rRNA of thermophilic and psychrophilic prokaryotes correlates inversely with their optimal growth temperatures

We report here the finding of a highly significant inverse correlation of the uracil content of 16S rRNA and the optimum growth temperature (T(opt)) of cultured thermophilic and psychrophilic prokaryotes. This correlation was significantly different from the weaker correlations between the contents of other nucleotides and T(opt). Analysis of the 16S rRNA secondary structure regions revealed a fall in the A:U base-pair content in step with the increase in T(opt) that was much steeper than that of mismatched base-pairs, which are thermodynamically less stable. These findings indicate that the 16S rRNA sequences of thermophiles and psychrophiles are under a strong thermo-adaptive pressure, and that structure–function constraints play a crucial role in determining their 16S rRNA nucleotide composition. The derived relationship between uracil content and T(opt) was used to develop an algorithm to predict the T(opt) values of uncultured prokaryotes lacking cultured close relatives and belonging to the phyla predominantly containing thermophiles. This algorithm may be useful in guiding the design of cultivation conditions for hitherto uncultured microbes

Weaponising microbes for peace

There is much human disadvantage and unmet need in the world, including deficits in basic resources and services considered to be human rights, such as drinking water, sanitation and hygiene, healthy nutrition, access to basic healthcare, and a clean environment. Furthermore, there are substantive asymmetries in the distribution of key resources among peoples. These deficits and asymmetries can lead to local and regional crises among peoples competing for limited resources, which, in turn, can become sources of discontent and conflict. Such conflicts have the potential to escalate into regional wars and even lead to global instability. Ergo: in addition to moral and ethical imperatives to level up, to ensure that all peoples have basic resources and services essential for healthy living and to reduce inequalities, all nations have a self-interest to pursue with determination all available avenues to promote peace through reducing sources of conflicts in the world. Microorganisms and pertinent microbial technologies have unique and exceptional abilities to provide, or contribute to the provision of, basic resources and services that are lacking in many parts of the world, and thereby address key deficits that might constitute sources of conflict. However, the deployment of such technologies to this end is seriously underexploited. Here, we highlight some of the key available and emerging technologies that demand greater consideration and exploitation in endeavours to eliminate unnecessary deprivations, enable healthy lives of all and remove preventable grounds for competition over limited resources that can escalate into conflicts in the world. We exhort central actors: microbiologists, funding agencies and philanthropic organisations, politicians worldwide and international governmental and non-governmental organisations, to engage – in full partnership – with all relevant stakeholders, to ‘weaponise’ microbes and microbial technologies to fight resource deficits and asymmetries, in particular among the most vulnerable populations, and thereby create humanitarian conditions more conducive to harmony and peace.Natural History Museum; Indian National Science Academ

The Fiscal Effects of Aid in Ethiopia Evidence from CVAR Applications

This article explores the fiscal effects of aid in Ethiopia using the Cointegrated Vector AutoRegressive (CVAR) methodology to model complex long-run and short-run dynamics. We use national data for 1961–2010, including a measure of aid capturing flows through the budget as measured by the recipient. The data suggests three main conclusions on the long-run equilibrium. First, government long-term spending plans are based on domestic sources, treating aid as an additional source of revenue. Second, both grants and loans are positively related to tax revenue. Third, aid is positively associated with spending, with a particularly strong relation between capital expenditure and grants. Overall, our results show that aid in Ethiopia had beneficial fiscal effects

Barriers to patient enrolment in phase III cancer clinical trials:interviews with clinicians and pharmaceutical industry representatives

OBJECTIVES: Phase III cancer clinical trials are expensive and time-consuming phases in drug development. Effective patient enrolment can reduce delays and save costs, offering patients an opportunity to benefit from innovative treatments. However, the current evidence base does not fully explain the persistence of barriers to patient enrolment in phase III cancer clinical trials. The aim was to explore clinicians' and pharmaceutical representatives' views on these barriers. DESIGN: A qualitative study was performed. In-depth information was collected from 15 experts in the field of oncology clinical trials, in particular clinical oncologists acting as principal investigators (PIs) and clinical research associates. By means of semistructured interviews, based on a questionnaire derived from our newly developed conceptual framework, they were asked to identify barriers to patient enrolment they had experienced and comment on barriers identified in literature. FINDINGS: Existing knowledge on barriers to patient enrolment was confirmed by all interviewees. Two new key barriers to patient enrolment were identified, that is, insufficient attention to the importance of clinical trial-based research in medical training and a trust gap between PIs and pharmaceutical representatives. A third important barrier was increasingly narrow patient inclusion criteria. CONCLUSIONS: The success rate of patient enrolment in phase III cancer clinical trials highly depends on the clinicians' willingness to take part in clinical trials. Raising awareness of the importance of clinical trials in medical training and among practising oncologists is recommended. Furthermore, to reduce barriers to patient enrolment, it is essential that both clinicians and pharmaceutical representatives acknowledge each other's expertise, become acquainted with each other's procedures and regulations, and work on building trust relationships. Finally, in accordance with our key findings, we propose to add two new barriers to our newly developed conceptual framework; insufficient attention to clinical trial research in medical training and trust gap.</p

Cardiovascular disease burden due to productivity losses in European Society of Cardiology countries

Objective Cardiovascular disease (CVD) is the leading cause of death across Europe. We estimated lost earnings (productivity losses) associated with premature mortality due to CVD, and separately for its main sub-categories of coronary heart disease and cerebrovascular disease, across 54 country members of the European Society of Cardiology (ESC). Methods & results We used a standardised approach to estimate working years and earnings lost due to premature death resulting from CVD across the 54 ESC member countries in 2018. Our population-based approach was based on national data on the number of deaths, employment rates and earnings by age group and sex. We discounted future working years and earnings lost to present values using a 3·5% annual rate. In 2018, there were 4.4 million deaths due to CVD across the 54 countries, with 7.1 million working years lost. This represented productivity losses due to premature death of €62 billion in 2018. Deaths due to coronary heart disease accounted for 47% (€29 billion) of all CVD costs, and cerebrovascular disease accounted for 18% (€11 billion). Approximately 60% (€37 billion) of all productivity losses occurred in the 28 EU-member states, despite accounting for only 42% (1.8 million) of deaths and 21% (1.5 million) of working years lost across the 54 countries. Conclusions Our study provides a snapshot of the economic consequences posed by premature mortality due to CVD across 54 countries in 2018. The considerable variation across countries highlights the potential gains from policies targeting prevention and care of cardiovascular diseases