Record of a colloquium organised by IUBS on the methodology of radiation measurement under water. [Translation from: Mem. Inst. Ital. Idrobiol. 17, 57-79, 1964]

These minutes report on colloquium on the methodology of radiation measurement under water. The meeting was held on 3-5 January 1957, at the Biological Station, Lunz, Austria. The participants of the colloquium discussed various methodologies of radiation measurements, basic methods such as Secchi Disc and underwater photometer as well as specialist equipment like the absolute radiation apparatus

The Freshwater Biological Association and the International Biological Programme (1961-1976)

The involvement of the FBA in the primary productivity program is reviewed

Keeping partners together: algorithmic results for the hospitals/residents problem with couples

The Hospitals/Residents problem with Couples (HRC) is a generalisation of the classical Hospitals/Residents problem (HR) that is important in practical applications because it models the case where couples submit joint preference lists over pairs of hospitals (h i ,h j ). We consider a natural restriction of HRC in which the members of a couple have individual preference lists over hospitals, and the joint preference list of the couple is consistent with these individual lists in a precise sense. We give an appropriate stability definition and show that, in this context, the problem of deciding whether a stable matching exists is NP-complete, even if each resident’s preference list has length at most 3 and each hospital has capacity at most 2. However, with respect to classical (Gale-Shapley) stability, we give a linear-time algorithm to find a stable matching or report that none exists, regardless of the preference list lengths or the hospital capacities. Finally, for an alternative formulation of our restriction of HRC, which we call the Hospitals/Residents problem with Sizes (HRS), we give a linear-time algorithm that always finds a stable matching for the case that hospital preference lists are of length at most 2, and where hospital capacities can be arbitrary

Combined super-/substring and super-/subsequence problems

Super-/substring problems and super-/subsequence problems are well-known problems in stringology that have applications in a variety of areas, such as manufacturing systems design and molecular biology. Here we investigate the complexity of a new type of such problem that forms a combination of a super-/substring and a super-/subsequence problem. Moreover we introduce different types of minimal superstring and maximal substring problems. In particular, we consider the following problems: given a set L of strings and a string S, (i) find a minimal superstring (or maximal substring) of L that is also a supersequence (or a subsequence) of S, (ii) find a minimal supersequence (or maximal subsequence) of L that is also a superstring (or a substring) of S. In addition some non-super-/non-substring and non-super-/non-subsequence variants are studied. We obtain several NP-hardness or even MAX SNP-hardness results and also identify types of "weak minimal" superstrings and "weak maximal" substrings for which (i) is polynomial-time solvable

An 8/5 approximation algorithm for a hard variant of stable marriage

When ties and incomplete preference lists are permitted in the Stable Marriage problem, stable matchings can have different sizes. The problem of finding a maximum cardinality stable matching in this context is NP-hard, even under very severe restrictions on the number, size and position of ties. In this paper, we describe a polynomial-time 8/5-approximation algorithm for a variant in which ties are on one side only and at the end of the preference lists. This variant is motivated by important applications in large scale centralized matching schemes

Alternative hypotheses linking the immune system and mate choice for good genes

Why do males often have extravagant morphological and behavioural traits, and why do females prefer to mate with such males? The answers have been the focus of considerable debate since Darwin's 'The descent of man, and selection in relation to sex' appeared in 1871. Recently, the broadening of investigation to include fields outside evolutionary biology has shed new light on mate choice and sexual selection. Here, we focus on a specific set of hypotheses relating the biology of resisting disease-causing organisms with the production of condition-dependent sexual signals (advertisements). We present a framework that distinguishes three different hypotheses about trade-offs within the immune system that affect general condition. The original Hamilton & Zuk hypothesis suggests that hosts fight off disease via resistance to particular pathogens, which lowers resistance to other pathogens. Changes in pathogens over evolutionary time in turn favours changes in which genes confer the best resistance. Alternatively, the immunocompetence hypotheses suggest that the energetic costs of mounting a response to any pathogen compete for resources with other things, such as producing or maintaining advertisements. Finally, improving resistance to pathogens could increase the negative impacts of the immune system on the host, via immunopathologies such as allergies or autoimmune diseases. If both disease and immunopathology affect condition, then sexual advertisements could signal a balance between the two. Studies of hypothesized links between genes, condition, the immune system and advertisements will require careful consideration of which hypothesis is being considered, and may necessitate different measures of immune system responses and different experimental protocols

General practice size determines participation in optional activities: cross-sectional analysis of a national primary care system

Background: There is widespread, unexplained variation in activity and outcome between general practices. <BR/> Aim: To explore the relationship between practice size and participation in optional activities, including the Quality and Outcomes Framework (QOF). <BR/> Design of study: Cross-sectional analyses of routinely available data on practice characteristics, QOF performance and optional activities including undergraduate teaching, postgraduate training, research, enhanced clinical data collection and service development. <BR/> Setting: All 1031 general practices were located in mainland Scotland. <BR/> Results: The most popular optional activity was undergraduate medical teaching, which involved 41% of all general practices. About a third of practices took part in postgraduate general practitioner training (29%), research (33%), enhanced clinical data collection through the Scottish Programme for Improving Clinical Effectiveness (31%) and the activities of the Scottish Primary Care Collaborative (33%). The most important driver of the number of activities undertaken by a practice is size with single handed, small and medium sized practices all undertaking a significantly lower number of activities than larger practices (P < 0.001). Deprivation had no overall effect, but was associated with lower rates of participation in postgraduate training. The average number of points achieved in the QOF ranged from 961 by the 18% of practices taking part in no optional activities, to 973 by 29% of practices taking part in one activity, 984 by 25% of practices taking part in two activities and 985 in 28% of practices taking part in three or more activities. Single handed practices in urban areas taking part in three or more additional activities had similar QOF point totals to larger practices taking part in three or more activities, and achieved 44 more QOF points than urban single-handed practices taking part in less than two additional activities. <BR/> Conclusions: Practice size is strongly related to participation in optional activities. There is a small but significant relationship between the practice size and number of QOF points achieved by practices taking part in less than two additional activities. Participation in optional activities is a possible indicator of cultural and organisational factors within practices, which constrain the volume and quality of services, which they are able to provide

How periodontal disease may contribute to cardiovascular disease

No abstract available