Cumulative or sequential assessment during hermit crab shell fights: effects of oxygen on decision rules

Agonistic interactions between animals are often settled by the use of repeated signals which advertise the resource-holding potential of the sender. According to the sequential assessment game this repetition increases the accuracy with which receivers may assess the signal, but under the cumulative assessment model the repeated performances accumulate to give a signal of stamina. These models may be distinguished by the temporal pattern of signalling they predict and by the decision rules used by the contestants. Hermit crabs engage in shell fights over possession of the gastropod shells that they inhabit. During these interactions the two roles of signaller and receiver may be examined separately because they are fixed for the duration of the encounter. Attackers rap their shell against that of the defender in a series of bouts whereas defenders remain tightly withdrawn into their shells for the duration of the contest. At the end of a fight the attacker may evict the defender from its shell or decide to give up without first effecting an eviction; the decision for defenders is either to maintain a grip on its shell or to release the shell and allow itself to be evicted. We manipulated fatigue levels separately for attackers and defenders, by varying the oxygen concentration of the water that they are held in prior to fighting, and examined the effects that this has on the likelihood of each decision and on the temporal pattern of rapping. We show that the vigour of rapping and the likelihood of eviction are reduced when the attacker is subjected to low oxygen but that this treatment has no effect on rates of eviction when applied to defenders. We conclude that defenders compare the vigour of rapping with an absolute threshold rather than with a relative threshold when making their decision. The data are compatible with the cumulative assessment model and with the idea that shell rapping signals the stamina of attackers, but do not fit the predictions of the sequential assessment game.

Synthesis of the alkaloid homaline in ( ) and natural (S,S)-(-) forms, using amination and transamidative ring expansion in liquid ammonia.

Crombie, Leslie; Haigh, David; Jones, Raymond C. F.; Mat-Zin, A.Rasid. Dep. Chem., Univ. Nottingham, Nottingham, UK. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) (1993), (17), 2047-54. CODEN: JCPRB4 ISSN: 0300-922X. Journal written in English. CAN 120:164608 AN 1994:164608 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract The alkaloid homaline I was prepd. in (?) and natural (S,S)-(-) forms. Linking of 2-azacyclooctanone units either directly or successively using 1,4-dihalogenobutanes or 1,4-dihalogenobut-2-ynes is examd. (?)-5-Methyl-4-phenyl-1,5-diazacyclooctan-2-one is first made by a 2,2'-dithiodipyridine/triphenylphosphine-mediated cyclization, and then by amination and transamidative ring expansion from N-(3-chloropropyl)-4-phenylazetidin-2-one in liq. ammonia, followed by N-methylation. Coupling through a 1,4-dihalogenobutane of either the N-methylated azalactam, or the unmethylated azalactam followed by methylation, gave homaline in (?) and meso forms. (R)-(-)-phenylglycine was converted via (S)-?-phenyl-?-alanine into an (S)-?-lactam which was then alkylated with 1-bromo-3-chloropropane, and aminated and ring expanded in liq. ammonia. Coupling of the homochiral azalactam (2 mol) so formed with 1,4-dibromobutane, followed by N-methylation, gave (S,S)-(-)-homaline identical with the natural material.

Study of the transamidative ring expansion of N--halogenoalkyl--lactams of alkyl chain lengths 2–12 in liquid ammonia and other liquid amines: syntheses of 7-, 8- and 9-membered 1,5-diaza cyclic ketones, including routes to (±)-dihydroperiphylline and (±)-celabenzine

N-(3-Halogenopropyl)-4-phenylazetidin-2-ones undergo amination in liquid ammonia followed by transamidative ring expansion to give the eight-membered 4-phenyl -1,5-diazacyclooctan-2-one in excellent yield. Ring expansion of the amines in liquid ammonia is found to be much more effective than in hydrocarbon solvents. Formation of 7-, 8-, and 9-membered azalactams from the requisite -halogenoalkyl--lactams is an excellent synthetic process, though it is not applicable to 10membered rings. In the cases of rings of 13-, 15- and 17-members, although amination and apparent expansion takes place, the large rings appear not to be stable to ammonia and the final products are acyclic amides. N-[4-Halogenobut-2(Z)-enyl]-4-phenylazetidin-2-one satisfactorily forms a 9-membered (Z)-olefinic azalactam, but the (E)-isomer gives an acyclic amino amide. By using alkyl-substituted -lactam side-chains, C-substituted medium rings can be obtained; the relative instability of N-acyl -lactams to ammonia, however, leads to acylamino amides rather than expanded rings.Employing ethylamine in place of ammonia, it is shown that N-ethylated azalactams are formed satisfactorily, and using allylamine, N-allyl medium rings capable of further elaboration are obtained. The chemistry of these systems is discussed. Using transamidation in liquid ammonia, a short synthesis of the 9-membered spermidine alkaloid (±)-dihydroperiphylline is reported. Synthesis of key intermediates, whose transformation into the 13-membered alkaloids of the celabenzine group has already been effected, has been carried out.X-Ray single-crystal structure determinations for 4-phenyl-1,5-diazacyclononan-2-one, trans-4-phenyl-8-methyl-1,5-diazacyclooctan-2-one and (Z)-4-phenyl-1,5-diazacyclonon-7-en-2-one are reported, and comment is made on certain conformational features.

Professional perspectives on decision making about the long-term care of older people

With the increasing pressure on social and health care resources, professionals have to be more explicit in their decision making regarding the long-term care of older people. This grounded theory study used 19 focus groups and nine semi-structured interviews (99 staff in total) to explore professional perspectives on this decision making. Focus group participants and interviewees comprised care managers, social workers, consultant geriatricians, general medical practitioners, community nurses, home care managers, occupational therapists and hospital discharge support staff. The emerging themes spanned context, clients, families and services. Decisions were often prompted by a crisis, hindering professionals seeking to make a measured assessment. Fear of burglary and assault, and the willingness and availability of family to help were major factors in decisions about living at home. Service availability in terms of public funding for community care, the availability of home care workers and workload pressures on primary care services influenced decision 'thresholds' regarding admission to institutional care. Assessment tools designed to assist decision making about the long-term care of older people need to take into account the critical aspects of individual fears and motivation, family support and the availability of publicly funded services as well as functional and medical needs.

Explicit argumentation as a supervisory tool for decision making in child protection cases involving human rights issues

This paper addresses the problems often faced by social workers and their supervisors in decision making where human rights considerations and child protection concerns collide. High profile court cases in the United Kingdom and Europe have consistently called for social workers to convey more clarity when justifying their reasons for interfering with human rights in child protection cases. The themes emerging from these case law decisions imply that social workers need to be better at giving reasons and evidence in more explicit ways to support any actions they propose which cause interference with Convention Rights. Toulmin (1958, 1985) offers a structured approach to argumentation which may have relevance to the supervision of child protection cases when social workers and managers are required to balance these human rights considerations. One of the key challenges in this balancing act is the need for decision makers to feel confident that any interventions resulting in the interference of human rights are both justified and proportionate. Toulmin’s work has already been shown to have relevance for assisting social workers navigate pathways through cases involving competing ethical and moral demands (Osmo and Landau, 2001) and more recently to human rights and decision making in child protection (Duffy et al, 2006). Toulmin’s model takes the practitioner through a series of stages where any argument or proposed recommendation (claim) is subjected to intense critical analysis involving exposition of its strengths and weaknesses. The author therefore proposes that explicit argumentation (Osmo and Landau, 2001) may help supervisors and practitioners towards safer and more confident decision making in child protection cases involving the interference of the human rights of children and parents. In addition to highlighting the broader context of human rights currently permeating child protection decision making, the paper will include case material to practically demonstrate the application of Toulmin’s model of argumentation to the supervision context. In this way the paper adopts a strong practice approach in helping to assist practitioners with the problems and dilemmas they may come up against in decision making in complex cases.

Choice and Welfare Reform: Lone Parents’ Decision Making around Paid Work and Family Life

Welfare-to-work policy in the UK sees ‘choice’ regarding lone parents’ employment decisions increasingly defined in terms of powers of selection between options within active labour market programmes, with constraints on the option of non-market activity progressively tightened. In this paper, we examine the wider choice agenda in public services in relation to lone-parent employment, focusing on the period of welfare reform following the 2007 Freud review of welfare provision. Survey data is used to estimate the extent to which recent policies promoting compulsory job search by youngest dependent child age map onto lone parents' own stated decision-making regarding if and when to enter the labour market. The findings indicate a substantial proportion of lone parents targeted by policy reform currently do not want a job and that their main reported reason is that they are looking after their children. Economically inactive lone mothers also remain more likely to have other chronic employment barriers, which traverse dependent child age categories. Some problems, such as poor health, sickness or disability, are particularly acute among those with older dependent children who are the target of recent activation policy.

Observation of Postsoliton Expansion Following Laser Propagation through an Underdense Plasma

The expansion of electromagnetic postsolitons emerging from the interaction of a 30 ps, 3 x 10(18) W cm(-2) laser pulse with an underdense deuterium plasma has been observed up to 100 ps after the pulse propagation, when large numbers of postsolitons were seen to remain in the plasma. The temporal evolution of the postsolitons has been accurately characterized with a high spatial and temporal resolution. The observed expansion is compared to analytical models and three-dimensional particle-in-cell results, revealing a polarization dependence of the postsoliton dynamics.