Identity of a Tilapia Pheromone Released by Dominant Males that Primes Females for Reproduction

Knowledge of the chemical identity and role of urinary pheromones in fish is scarce, yet it is necessary in order to understand the integration of multiple senses in adaptive responses and the evolution of chemical communication [1]. In nature, Mozambique tilapia (Oreochromis mossambicus) males form hierarchies, and females mate preferentially with dominant territorial males, which they visit in aggregations or leks [2]. Dominant males have thicker urinary bladder muscular walls than subordinates or females and store large volumes of urine, which they release at increased frequency in the presence of subordinate males or preovulatory, but not postspawned, females [3–5]. Females exposed to dominant-male urine augment their release of the oocyte maturation-inducing steroid 17α,20β-dihydroxypregn-4-en-3-one (17,20β-P) [6]. Here we isolate and identify a male Mozambique tilapia urinary sex pheromone as two epimeric (20α- and 20β-) pregnanetriol 3-glucuronates. We show that both males and females have high olfactory sensitivity to the two steroids, which cross-adapt upon stimulation. Females exposed to both steroids show a rapid, 10-fold increase in production of 17,20β-P. Thus, the identified urinary steroids prime the female endocrine system to accelerate oocyte maturation and possibly promote spawning synchrony. Tilapia are globally important as a food source but are also invasive species, with devastating impact on local freshwater ecosystems [7, 8]. Identifying the chemical cues that mediate reproduction may lead to the development of tools for population control [9–11].

Electro-olfactograms in response to chromatographic fractions of food-related odorants in the Senegalese sole, Solea senegalensis

The Bohr effect, which can be most generally defined as the influence of pH on the oxygen binding affinity of proteins, is a common feature of respiratory pigments, ranging from the haemocyanins of molluscs and crustaceans to the haemoglobins of vertebrates. Its physiological role is generally seen in the facilitation of oxygen release from respiratory pigments during tissue acidosis. The magnitude of the effect can be influenced by a multitude of factors such as temperature, carbon dioxide, chloride ions, organic phosphates and the investigated pH range. Here we present data on the maximal alkaline Bohr effect in haemoglobins from a large number of species covering all vertebrate classes, obtained at physiological temperatures in the presence of 100 mM chloride ions and the absence of carbon dioxide and organic phosphates.

A influência da liquidez nas decisões de investimento das empresas moderada pelo ambiente da indústria e pela estratégia empresarial: o caso da indústria transformadora portuguesa

Com este estudo pretende-se investigar a relação da liquidez com o investimento das empresas e avaliar o papel moderador do ambiente da indústria e da estratégia empresarial na relação anterior. Literatura recente, que se seguiu ao trabalho de Fazzari, Hubbard e Petersen (1988), sugere que a intensidade da relação entre os fluxos de caixa e o investimento é reveladora dos constrangimentos financeiros das empresas no acesso ao mercado de capitais. A investigação aplicada é desenvolvida com uma amostra de empresas não financeiras da indústria transformadora portuguesa, período 1998-2005. São estimados dois modelos para dados em painel, um restrito com variáveis financeiras, ambientais e estratégicas e outro, mais alargado, onde se incluem, também, variáveis interactivas. O método de estimação utilizado é a regressão linear múltipla de efeitos fixos para a indústria e ano com o estimador robusto das variâncias. Através do modelo restrito e recorrendo à regressão de subgrupos, constituídos com base em indicadores teoricamente tradutores dos constrangimentos financeiros das empresas, capacidade de endividamento a médio e longo prazo e endividamento total, constata-se que a relação entre os fluxos de caixa e o investimento é sempre positiva e intensifica-se à medida que a capacidade de financiamento da empresa diminui. Através do modelo alargado e recorrendo, em simultâneo, à regressão de subgrupos e à regressão moderada observa-se que o ambiente da indústria (munificência e dinamismo) e a estratégia da empresa (inovação e diversificação) moderam a relação dos fluxos de caixa com o investimento, intensificando-a ou atenuando-a. Este facto sugere que os factores ambientais e estratégicos influenciam os custos de agência e de selecção adversa das empresas e, consequentemente, o acesso aos fundos de que necessitam. Ao evidenciar as implicações financeiras das opções estratégicas e das características do ambiente da indústria, o estudo contribui para o aprofundamento do conhecimento dos determinantes do investimento e para a melhoria da gestão das empresas.

Chemical communication in the Mozambique tilapia: a role for amino acids

The Mozambique tilapia (Oreochromis mossambicus) is a maternal mouthbrooding cichlid from the southern Africa. The olfactory sensitivity of the species to 20 amino acids was assessed using the electro-olfactogram (EOG). We estimated whether the olfactory potency of the polar fraction of male urine can be explained by the presence of identified amino acids. In addition, filtrate and amino acid mixture of the urine of Nile tilapia were used to estimate their olfactory potency for O.mossambicus. Finally, concentrations of the main amino acids were measured in the urine of males of different social status and the correlations between amino acid concentration and hierarchical status were explored. L-cysteine, L-glutamine and L-threonine were the most potent stimuli at M while L-proline and L-aspartate were the least potent. Four groups of amino acids were identified according to their thresholds of detection and three groups – according to the similarity of their ɣ-factors. The estimated threshold of detection for O.mossambicus mixture was higher than that for the filtrate. On the contrary, the threshold of detection for the mixture of Nile tilapia was lower than that for the filtrate The concentration of L-arginine in the urine was positively correlated with fish dominance index. Both L-arginine and L-glutamic acid concentrations had much greater variability in dominant males (DI˃0.5) than in subordinate males (DI˂0.5). The urinary concentrations of L-phenylalanine had similar variability in dominant and subordinate groups. The Mozambique tilapia has olfactory sensitivity to all twenty amino acids tested. The fish showed more acute sensitivity to conspecific urine filtrate than to the heterospecific. Olfactory potency of O.mossambicus filtrate can be largely but not fully explained by the presence of L-arginine, L-glutamic acid and L-phenylalanine. Larginine and L-glutamic acid may indicate the dominance status of the fish and, possibly, individual identity.

Approaching Models of Nursing from a Postmodernist Perspective

This paper explores some questions about the use of models of nursing. These questions make various assumptions about the nature of models of nursing, in general and in particular. Underlying these assumptions are various philosophical positions which are explored through an introduction to postmodernist approaches in philosophical criticism. To illustrate these approaches, a critique of the Roper et al. model is developed, and more general attitudes towards models of nursing are examined. It is suggested that postmodernism offers a challenge to many of the assumptions implicit in models of nursing, and that a greater awareness of these assumptions should lead to nursing care being better informed where such models are in use.

The Art of Nursing in a Postmodern Context

Notions of the "postmodern" pervade various fields of study, but have rarely been applied to the practice and theory of nursing. This paper uses some conceptions of the "postmodern" to remedy this. Though there are many contested usages of the term, here "postmodern" will be used broadly in a periodical sense to trace changes in society and culture from the "modernism" of the 18th and 19th centuries to current concerns about "postmodernism". How these changes have been reflected in nursing practice and nursing theory will be explored. The changing use of the term "modern" to describe up-to-date practice will be addressed in the course of this. It is suggested that contextualizing nursing as a social/cultural activity in this way offers perspectives which will help us untangle the conflicting agendas and issues which form the fabric of the social world in which current nursing takes place, enabling us to act more effectively in promoting our own professional agendas.

A Taxonomy for Developing Cultural Competence

This paper proposes a taxonomy to develop culturally competent practitioners. Arguments about what this might mean and how this could be achieved are discussed first, identifying problems with multicultural and antiracist approaches. The model follows the cognitive, emotional and behavioural levels of Steinaker and Bell's experiential taxonomy. Five elements are proposed: cultural awareness, cultural knowledge, cultural understanding, cultural sensitivity and cultural competence. These could address, in increasingly sophisticated and increasingly praxis-oriented ways, issues of power and the construction of meanings and identities which go beyond essentialist notions of ethnicity.

University Chorale, March 1, 1977

Concert program for University Chorale, March 1, 1977

The Contemporary Group, October 24, 1979

Concert program for The Contemporary Group, October 24, 1979

On absence: society’s return to barbarians

The problem of social exclusion is dealt here through the lens of a particularly radical social theory, that of autopoietic society by Niklas Luhmann. Here, exclusion is included in society, no longer as an issue for care, integration and therapy, but as a mechanism to show the importance of the visibility of exclusion. The inclusion of exclusion in autopoiesis is a far-reaching step that demands a revisiting of the concept of autopoietic society. This article proposes a radicalization of the concept on the basis of an acknowledgment of the impossibility of communication with the excluded. This acknowledgement conditions society from within. It is built upon the Luhmannian description of Barbarism as the included exclusion, and is further conceptualized as its excess, as a 'space of absence'. Within autopoiesis, absence is described as an aporetic rather than a paradoxical structure, a memento vanitas that irritates the system from within, constantly reminding it of its limitations.

A Student Composers' Recital, May 7, 1959 8:30pm

Concert program for A Student Composers' Recital, May 7, 1959

Twentieth Century Music December 6, 1971

Concert Program for Twentieth Century Music, Dec. 6, 1971

The battle of Cable Street

This witness seminar on the events in the East End of London of 4 October 1936, traditionally known as the ‘Battle of Cable Street’, was held at the Institute of Historical Research on 1 May 1991. It was chaired by Professor Geoffrey Alderman and introduced by Noreen Branson. The participants were Sid Bailey (former member of the BUF), Dr David Cesarani, Tony Gilbert, Charlie Goodman, Joyce Goodman, Professor Colin Holmes, Frank Lesser, Kevin Morgan (biographer of Harry Pollitt), Phil Piratin (Communist MP for Mile End 1945–50), Michael Quill, Jack Shaw, Harold Smith, Ronald F. Webb (former member of the BUF) and Len Wise (former member of the BUF). Yvonne Kapp was unable to attend but she sent a short account of her recollections of the event and this has been included with this transcript.

Hydrogeophysical data integration at larger scales: Application of Bayesian sequential simulation for the characterization of heterogeneous alluvial aquifers

Knowledge of the spatial distribution of hydraulic conductivity (K) within an aquifer is critical for reliable predictions of solute transport and the development of effective groundwater management and/or remediation strategies. While core analyses and hydraulic logging can provide highly detailed information, such information is inherently localized around boreholes that tend to be sparsely distributed throughout the aquifer volume. Conversely, larger-scale hydraulic experiments like pumping and tracer tests provide relatively low-resolution estimates of K in the investigated subsurface region. As a result, traditional hydrogeological measurement techniques contain a gap in terms of spatial resolution and coverage, and they are often alone inadequate for characterizing heterogeneous aquifers. Geophysical methods have the potential to bridge this gap. The recent increased interest in the application of geophysical methods to hydrogeological problems is clearly evidenced by the formation and rapid growth of the domain of hydrogeophysics over the past decade (e.g., Rubin and Hubbard, 2005).