Le nombre de reines chez les fourmis et sa conséquence sur l'organisations sociale

Nearly half of all ant species form polygyne societies (cohabitation of more than a single egg-laying queen). These queens are generally smaller and store fewer fat reserves than queens from monogyne colonies. Most queens in polygyne colonies (70-100 pour 100) are inseminated, although this proportion varies among species, and even among populations of the same species. They exhibit mutual tolerance and they all contribute to the reproductive effort of the colony. Nevertheless, their individual fecundity is considerably reduced compared with that of queens from monogyne colonies. This reduction in fecundity seems to be due to some form of mutual inhibition, in some cases the secretion by each female of a substance suppressing egg production in other queens has been implicated. In a few species, queens are organized into a hierarchy such that certain queens lay more eggs than others or even monopolize egg-laying (functional monogyny). Polygyny is linked to a particular life history. It rarely results from the association of several foundresses (primary polygyny). Usually, it is due to the adoption of young queens by an established nest just after a nuptial flight. This secondary polygyny means that the dispersal of the species is limited and is achieved by the budding of a mother nest. Thus colony founding is dependent; with workers accompanying young queens in establishing new colonies. Observation of closely related species exhibiting different social organizations, some monogyne and others polygyne, shows a possible link between queen number and ecological conditions: polygyne forms are more frequent in unstable habitats susceptible to rapid change, such as that caused by human activity. The existence of polygyne societies is an intriguing evolutionary mystery. Research into the origin and maintenance of polygyny focuses on patterns of speciation in relation to queen number and the different theories put forth for the evolution of eusociality, mainly kin selection and mutualism.

Tracking cost savings from competitive tendering in the short and long run

A major initiative of the Thatcher and Major Conservative administrations was that public sector ancillary and professional services provided by incumbent direct service organisations [DSOs] be put out to tender. Analyses of this initiative, in the UK and elsewhere, found costs were often reduced in the short run. However, few if any studies went beyond the first round of tendering. We analyze data collected over successive rounds of tendering for cleaning and catering services of Scottish hospitals in order to assess the long term consequences of this initiative. The experience of the two services was very different. Cost savings for cleaning services tended to increase with each additional round of tendering and became increasingly stable. In accordance with previous results in the literature, DSOs produced smaller cost reductions than private contractors: probably an inevitable consequence of the tendering process at the time. Cost savings from DSOs tended to disappear during the first round of tendering, but they appear to have been more permanent in successive rounds. Cost savings for catering, on the other hand, tended to be much smaller, and these were not sustained.

Administering brief motivational interventions to young men: Results from a pilot census transmissible study among 19 year-old francophone Swiss men.

AIMS - To pilot the implementation of brief motivational intervention (BMI) among conscripts, and to test the effectiveness of BMI in young men voluntarily showing up for a single face-to-face alcohol BMI session. Participants were conscripts attending the army recruitment process in Lausanne. This process is mandatory for all Swiss males at age 19 and Lausanne serves all francophone Swiss men. METHODS - Of 3'227 young men that were seen during the army recruitment procedures, 445 voluntarily showed up for a BMI and 367 were included in the study (exclusions were random and unsystematic and related to organizational aspects in the recruitment center). After an initial assessment, subjects were randomized into two groups: an immediate BMI and a 6-month delayed BMI (waiting list design). A 6-month follow-up assessment was conducted in both groups. BMI was a face-to-face 20 minutes counseling session with a psychologist trained in motivational interviewing at baseline and a telephone session for the control group at follow-up. Strategies of BMI included the exploration and evocation of a possible behavior change, importance of future change, readiness to change, and commitment to change. A filmed example of such an intervention is available in French at www.alcoologie.ch. RESULTS - All procedures are now fully implemented and working and the provision of preventive efforts found general approval by the army. 3'227 were eligible for BMI and 445 of them (13.8%) showed up for receiving a BMI. 367 were included in the study, 181 in the BMI group and 186 in the control group. More than 86% of those included were reached at follow-up. With one exception all findings on alcohol use went in the expected direction, i.e. a stronger decrease in alcohol use (or a smaller increase as for usual weekly drinking amount) in the BMI group. The risk for risky single occasion drinking (RSOD) decreased from 57% at-risk users at baseline to 50.6%, i.e. a 6.4% point decrease in the BMI group, while there was only a 0.6% point decrease (from 57.5% to 56.9%) in the control group. Moreover, the study showed that there was a likelihood of crossover effects for other substances like tobacco smoking and cannabis use. Despite these encouraging and consistent positive findings, none reached significance at conventional levels (p < 0.05). DISCUSSION - Data suggest a beneficial impact of BMI on alcohol use outcomes and potential effect on other substance use in 19-year old men attending the army recruitment and showing up voluntarily for BMI. As the main aim was to implement and test feasibility of conducting BMI in this setting none of our findings reached statistical significance. The consistency of findings across measures and substances, however, raises hope that non-significance in the present study does not mean no effect, but mainly insufficient power of this pilot study. [Authors]

The Electoral Determinants of Collective Remittances: The Mexican 3x1 Program for Migrants

The 3x1 Program for Migrants is a matching grant scheme that seeks to direct the money sent by migrant organizations abroad to the provision of public and social infrastructure, and to productive projects in migrants’ communities of origin. To do so, the municipal, state, and federal administrations match the amount sent by hometown associations by 3 to 1. This opens the door to the political manipulation of the program. We explore the impact of a particular facet of Mexican political life on the operation of the 3x1: its recent democratization and the increasing political competition at the municipal level. Relying on the literature on redistributive politics, we posit that an increasing number of effective parties in elections may have two different effects. On the one hand, the need to cater to more heterogeneous constituencies may increase the provision of public projects. On the other hand, since smaller coalitions are needed to win elections under tighter competition, fewer public and more private (clientelistic) projects could be awarded. Using a unique dataset on the 3x1 Program for Migrants for over 2,400 municipalities in the period 2002 through 2007, we find a lower provision of public goods in electorally competitive jurisdictions. Thus, we remain sceptical about the program success in promoting public goods in politically competitive locations with high migration levels.

Analyzing the effects of transient faults into applications

As computer chips implementation technologies evolve to obtain more performance, those computer chips are using smaller components, with bigger density of transistors and working with lower power voltages. All these factors turn the computer chips less robust and increase the probability of a transient fault. Transient faults may occur once and never more happen the same way in a computer system lifetime. There are distinct consequences when a transient fault occurs: the operating system might abort the execution if the change produced by the fault is detected by bad behavior of the application, but the biggest risk is that the fault produces an undetected data corruption that modifies the application final result without warnings (for example a bit flip in some crucial data). With the objective of researching transient faults in computer system’s processor registers and memory we have developed an extension of HP’s and AMD joint full system simulation environment, named COTSon. This extension allows the injection of faults that change a single bit in processor registers and memory of the simulated computer. The developed fault injection system makes it possible to: evaluate the effects of single bit flip transient faults in an application, analyze an application robustness against single bit flip transient faults and validate fault detection mechanism and strategies.

Ectodysplasin regulates hormone-independent mammary ductal morphogenesis via NF-κB.

Ductal growth of the mammary gland occurs in two distinct stages. The first round of branching morphogenesis occurs during embryogenesis, and the second round commences at the onset of puberty. Currently, relatively little is known about the genetic networks that control the initial phases of ductal expansion, which, unlike pubertal development, proceeds independent of hormonal input in female mice. Here we identify NF-κB downstream of the TNF-like ligand ectodysplasin (Eda) as a unique regulator of embryonic and prepubertal ductal morphogenesis. Loss of Eda, or inhibition of NF-κB, led to smaller ductal trees with fewer branches. On the other hand, overexpression of Eda caused a dramatic NF-κB-dependent phenotype in both female and male mice characterized by precocious and highly increased ductal growth and branching that correlated with enhanced cell proliferation. We have identified several putative transcriptional target genes of Eda/NF-κB, including PTHrP, Wnt10a, and Wnt10b, as well as Egf family ligands amphiregulin and epigen. We developed a mammary bud culture system that allowed us to manipulate mammary development ex vivo and found that recombinant PTHrP, Wnt3A, and Egf family ligands stimulate embryonic branching morphogenesis, suggesting that these pathways may cooperatively mediate the effects of Eda.

Dynamics of fibrosis production and resorption in intestinal schistosomiasis of mice

A histological, morphometric and immunocytochemical study of schistosomal periovular granulomas in the liver and intestines of mice revealed that intestinal granulomas are smaller and contain less collagen than those in the liver. After curative treatment intestinal granulomas undergo a relatively more rapid resorption, although the general pattern of collagen degradation apparently does not differ from that observed in the liver. Tendency to form scattered, usually isolated granulomas that are only mildly fibrogenic, coupled with a well-balanced process of resorption appear as the explanation why intestinal fibrosis is not an outstanding feature of schistosomiasis as it is in the liver.

Aging and motor programming: differential effects according to the selection of action

There are controversial reports about the effect of aging on movement preparation, and it is unclear to which extent cognitive and/or motor related cerebral processes may be affected. This study examines the age effects on electro-cortical oscillatory patterns during various motor programming tasks, in order to assess potential differences according to the mode of action selection. Twenty elderly (EP, 60-84 years) and 20 young (YP, 20-29 years) participants with normal cognition underwent 3 pre-cued response tasks (S1-S2 paradigm). S1 carried either complete information on response side (Full; stimulus-driven motor preparation), no information (None; general motor alertness), or required free response side selection (Free; internally-driven motor preparation). Electroencephalogram (EEG) was recorded using 64 surface electrodes. Alpha (8-12 Hz) desynchronization (ERD)/synchronization (ERS) and motor-related amplitude asymmetries (MRAA) were analyzed during the S1-S2 interval. Reaction times (RTs) to S2 were slower in EP than YP, and in None than in the other 2 tasks. There was an Age x Task interaction due to increased RTs in Free compared to Full in EP only. Central bilateral and midline activation (alpha ERD) was smaller in EP than YP in None. In Full just before S2, readiness to move was reflected by posterior midline inhibition (alpha ERS) in both groups. In Free, such inhibition was present only in YP. Moreover, MRAA showed motor activity lateralization in both groups in Full, but only in YP in Free. The results indicate reduced recruitment of motor regions for motor alertness in the elderly. They further show less efficient cerebral processes subtending free selection of movement in elders, suggesting reduced capacity for internally-driven action with age.

Variació dels estatges vegetals a l'àrea de la Bruguera (Girona) en els darrers cent anys

Treball de recerca realitzat per alumnes d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit cientí­fic del Jovent l'any 2009. Aquest treball s'ha basat en la comparació altitudinal de determinades espècies vegetals (i per tant dels estatges) respecte els últims cent anys en una zona de la vall de Ribes; concretament des de la serra de St. Amanç fins a la població de Bruguera, passant per els Llisos del Taga. La realització del treball implica primerament la recerca d'estudis i dades anteriors fets sobre el tema, que generalment es basaria en dos estudis ja esmentats en el treball, els quals són un catàleg florístic de la vall de Ribes (de Josep Vigo) i un article de característiques molt semblants al nostre treball (de Jonathan Lenoir), així com també l¡elecció de la metodologia i de les espècies a estudiar. L'altra part es basa en fer un comptatge i identificació de les espècies trobades en diferents zones. En el moment de fer la delimitació de les zones hem tingut en compte l'alçada i l'orientació i s'han subdividit aquestes zones en quadrants per facilitar el comptatge i identificació. Una vegada comparats els resultats amb els estudis fets anteriorment s'ha arribat a la conclusió que hi havia un canvi altitudinal de les espècies prou significatiu. Unes de les interpretacions d'aquest resultat observat podria lligar-se al canvi de temperatures que ha sofert la vall en els últims anys degut al canvi climàtic.

Desciption of Cribomazocraes travassosi n. sp. (Monogenea: Mazocraeidae), a fish parasite from the Atlantic Ocean

Cribomazocraes travassosi n. sp. is described from Harengula clupeola (Cuvier, 1829) from Rio de Janeiro, coast, Brazil. It differs from C. nagibinae, Mamaev, 1981 in the size and shape of opisthohaptor and lappet and in the smaller size of anchors. From C. bychowskyi it also differs in the extension of vittelaria. A key for the species of the genus is presented.

Sociogenomics of Cooperation and Conflict during Colony Founding in the Fire Ant Solenopsis invicta.

One of the fundamental questions in biology is how cooperative and altruistic behaviors evolved. The majority of studies seeking to identify the genes regulating these behaviors have been performed in systems where behavioral and physiological differences are relatively fixed, such as in the honey bee. During colony founding in the monogyne (one queen per colony) social form of the fire ant Solenopsis invicta, newly-mated queens may start new colonies either individually (haplometrosis) or in groups (pleometrosis). However, only one queen (the "winner") in pleometrotic associations survives and takes the lead of the young colony while the others (the "losers") are executed. Thus, colony founding in fire ants provides an excellent system in which to examine the genes underpinning cooperative behavior and how the social environment shapes the expression of these genes. We developed a new whole genome microarray platform for S. invicta to characterize the gene expression patterns associated with colony founding behavior. First, we compared haplometrotic queens, pleometrotic winners and pleometrotic losers. Second, we manipulated pleometrotic couples in order to switch or maintain the social ranks of the two cofoundresses. Haplometrotic and pleometrotic queens differed in the expression of genes involved in stress response, aging, immunity, reproduction and lipid biosynthesis. Smaller sets of genes were differentially expressed between winners and losers. In the second experiment, switching social rank had a much greater impact on gene expression patterns than the initial/final rank. Expression differences for several candidate genes involved in key biological processes were confirmed using qRT-PCR. Our findings indicate that, in S. invicta, social environment plays a major role in the determination of the patterns of gene expression, while the queen's physiological state is secondary. These results highlight the powerful influence of social environment on regulation of the genomic state, physiology and ultimately, social behavior of animals.

Comparable Survival Between HIV+ and HIV- non-Hodgkin and Hodgkin Lymphoma Patients Undergoing Autologous Peripheral Blood Stem Cell Transplantation.

Autologous stem cell transplantation (ASCT) has been successfully used in HIV-related lymphoma (HIV-Ly) patients on highly active antiretroviral therapy. We report the first comparative analysis between HIV-Ly and a matched cohort of HIV(-) lymphoma patients. This retrospective European Group for Blood and Marrow Transplantation study included 53 patients (66% non-Hodgkin and 34% Hodgkin lymphoma) within each cohort. Both groups were comparable except for the higher proportion of males, mixed-cellularity Hodgkin lymphoma and patients receiving granulocyte colony-stimulating factor before engraftment and a smaller proportion receiving total body irradiation-based conditioning within the HIV-Ly cohort. Incidence of relapse, overall survival, and progression-free survival were similar in both cohorts. A higher nonrelapse mortality within the first year after ASCT was observed in the HIV-Ly group (8% vs 2%), predominantly because of early bacterial infections, although this was not statistically significant and did not influence survival. Thus, within the highly active antiretroviral therapy era, HIV patients should be considered for ASCT according to the same criteria adopted for HIV(-) lymphoma patients.

Diseño de filtros de onda acústica basados en estructuras "half lattice"

En los últimos tiempos la telefonía móvil ha experimentado una reducción de los terminales gracias a la miniaturización de los filtros a frecuencias de microondas. Los filtros pasa banda más utilizados son los basados en la tecnología SAW, sin embargo son incompatibles con tecnologías de silicio y su comportamiento se degrada a frecuencias superiores de 3 GHz, por ello los estudios actuales se centran en la tecnología BAW. Las dos arquitecturas convencionales de filtros basados en resonadores BAW unidos eléctricamente son el ladder y lattice. Sin embargo, en este proyecto se estudiará la topología half lattice, la cual presenta un mejor comportamiento y unas dimensiones más reducidas. Para ello se obtendrán las ecuaciones de diseño del filtro, y con ellas se realizará la implementación a partir de la frecuencia central y el ancho de banda relativo.

On Strategy-proofness and symmetric single-peakedness

We characterize the class of strategy-proof social choice functions on the domain of symmetric single-peaked preferences. This class is strictly larger than the set of generalized median voter schemes (the class of strategy-proof and tops-only social choice functions on the domain of single-peaked preferences characterized by Moulin (1980)) since, under the domain of symmetric single-peaked preferences, generalized median voter schemes can be disturbed by discontinuity points and remain strategy-proof on the smaller domain. Our result identifies the specific nature of these discontinuities which allow to design non-onto social choice functions to deal with feasibility constraints.

Remarks, on six species of Heterakid Nematodes parasites of brazilian Tinamid birds with description of a new species

Nematodes representing five species of the genus Heterakis, namely: H. inglisi n. sp., H. alata, H. gallinarum, H. spiculatus and one species of the genus Odontoterakis, O. multidentata, were studied. Heterakis inglisi n. sp. closely resembles H. spiculatus, differing from it by smaller size of spicules, precloacal sucker and terminal spike of the tail in the males. Heterakis arquata and H. brasiliana are only listed, for they were not found during the present study. Odontoterakis multidentata is reported in Brazil for the first time. New host records are estabilished for most of the species. These species are fully illustrated.