On the sound of snapping shrimp

Fluid dynamics video: Snapping shrimp produce a snapping sound by an extremely rapid closure of their snapper claw. Our high speed imaging of the claw closure has revealed that the sound is generated by the collapse of a cavitation bubble formed in a fast flowing water jet forced out from the claws during claw closure. The produced sound originates from the cavitation collapse of the bubble. At collapse a short flash of light is emitted, just as in single bubble sonoluminescence. A model based on the Rayleigh-Plesset equation can quantitatively account for the visual and acoustical observations.Comment: Fluid dynamics vide

Barriers to and Efficacy of Point-of-Use Chemical Drinking Water Treatment in Kolda, Senegal, West Africa

Hundreds of thousands throughout the Kolda region in southern Senegal rely on potentially contaminated well water as their drinking source. Chemical treatment of the water using a small amount of chlorine bleach has been shown to increase its safety for human consumption; however, the vast majority of people in the region do not disinfect water before they drink it. In this study, 97 individuals (47 water Treaters and 51 Non-Treaters) were surveyed on motivations and barriers towards bleaching or not bleaching their water, and microbiological field testing was undertaken to examine the effectiveness of treatment in the field. The microbial tests showed treated water was significantly less contaminated than untreated water in both coliform and Escherichia coli counts. Due to the efficacy of the method, continuation of the promotion of chemical drinking water treatment is recommended. Ten recommendations for future water treatment interventions in Kolda are provided in the discussion of this report. These recommendations were derived from survey results as well as from the available literature on the topic

The response of bispectral index to laryngoscopy, comparison between hemispheres in patients with a brain tumour versus a healthy control group

Background and Goal of Study: Electroencephalogram during anaesthesia may be affected by brain tumour.(1) We studied whether patients with a brain tumour have different BIS responses after laryngoscopy (LAR). We compared tumour patients with healthy control patients. Materials and Methods: After EC approval, 40 ASA 1 or 2 patients (control) and 41 intracranial tumour patients(tumour) received standardized anaesthesia while measuring bilateral BIS (BIS VISTAXP4 with bilateral sensor).(Covidien, Dublin, Ireland) Remifentanil was randomized to 3 or 5ng/ml effect‐site concentration (Minto) and maintained throughout the study. Propofol effect‐site concentration(CePROP)(Schnider) was set at 2 μg/ml and increased with incremental steps of 0.5 μg/ml until loss of consciousness was observed. After 3 minutes, laryngoscopy was performed and BIS was monitored during one minute. The median BIS of 1 minute before LAR is subtracted from the median BIS one minute after LAR to obtain delta BIS for each hemisphere. We tested if delta BIS is significantly different between hemispheres in control, between healthy and diseased hemispheres in tumour and between ipsilateral control and tumour hemispheres. Statistical significance was set at p< 0.05. Results and Discussion: No demographic differences were present except for age.(table 1) Delta BIS is not statistically different, neither between hemispheres in control, nor between healthy and diseased hemispheres in tumour groups.(table 2) No significant difference was found in delta BIS between ipsilateral control and pathological hemispheres. Conclusion(s): Bilateral BIS does not provide additional information on responsiveness to a standardized stimulus. We could not observe major differences in bilateral BIS response between control and brain tumour patients. Unilateral BIS monitoring seems to be equally informative in healthy and brain tumour patients compared to bilateral monitoring

Foreign ant queens are accepted but produce fewer offspring

Understanding social evolution requires us to understand the processes regulating the number of breeders within social groups and how they partition reproduction. Queens in polygynous (multiple queens per colony) ants often seek adoption in established colonies instead of founding a new colony independently. This mode of dispersal leads to potential conflicts, as kin selection theory predicts that resident workers should favour nestmate queens over foreign queens. Here we compared the survival of foreign and resident queens as well as their relative reproductive share. We used the ant Formica exsecta to construct colonies consisting of one queen with workers related to this resident queen and introduced a foreign queen. We found that the survival of foreign queens did not differ from that of resident queens over a period of 136days. However, the genetic analyses revealed that resident queens produced a 1.5-fold higher number of offspring than introduced queens, and had an equal or higher share in 80% of the colonies. These data indicate that some discrimination can occur against dispersing individuals and that dispersal can thus have costs in terms of direct reproduction for dispersing queen

Genetic clusters and sex-biased gene flow in a unicolonial Formica ant

BACKGROUND: Animal societies are diverse, ranging from small family-based groups to extraordinarily large social networks in which many unrelated individuals interact. At the extreme of this continuum, some ant species form unicolonial populations in which workers and queens can move among multiple interconnected nests without eliciting aggression. Although unicoloniality has been mostly studied in invasive ants, it also occurs in some native non-invasive species. Unicoloniality is commonly associated with very high queen number, which may result in levels of relatedness among nestmates being so low as to raise the question of the maintenance of altruism by kin selection in such systems. However, the actual relatedness among cooperating individuals critically depends on effective dispersal and the ensuing pattern of genetic structuring. In order to better understand the evolution of unicoloniality in native non-invasive ants, we investigated the fine-scale population genetic structure and gene flow in three unicolonial populations of the wood ant F. paralugubris. RESULTS: The analysis of geo-referenced microsatellite genotypes and mitochondrial haplotypes revealed the presence of cryptic clusters of genetically-differentiated nests in the three populations of F. paralugubris. Because of this spatial genetic heterogeneity, members of the same clusters were moderately but significantly related. The comparison of nuclear (microsatellite) and mitochondrial differentiation indicated that effective gene flow was male-biased in all populations. CONCLUSION: The three unicolonial populations exhibited male-biased and mostly local gene flow. The high number of queens per nest, exchanges among neighbouring nests and restricted long-distance gene flow resulted in large clusters of genetically similar nests. The positive relatedness among clustermates suggests that kin selection may still contribute to the maintenance of altruism in unicolonial populations if competition occurs among clusters

Le non-recours aux prestations sociales et sanitaires : quelles implications pour la citoyenneté sociale?

Since the 1960s, a specific stream of literature in the field of social welfare has been concerned with the phenomenon of non-take-up, i.e. people who are entitled to social benefits but do not receive them. This issue of non-take-up is becoming increasingly salient and reaching policy agendas, including in Switzerland. It questions both the conditions of access to social benefits and their adequacy or even legitimacy when some people prefer not to claim their rights. What does non-take-up say about the aims of social policies and the way they are perceived by concerned people? What does it say about the underlying norms of those policies and the ways these norms are incorporated or contested by (potential) beneficiaries? What does it say about the public service and its capacity to reach its communities and support them? This special issue starts with an introduction to the topic of non-take-up of health and social benefits, focusing more specifically on the case of Switzerland. Building on this state of the art, the agenda is further developed to explore what non-take-up of social benefits says about the reconfiguration of the relationship between citizens and the state. The five authors of the special issues contribute to this new research agenda in three different ways: by emphasizing the temporal dimension of non-take-up; by supporting a view of recipients as capable and critical actors; and by arguing for a systemic and relational approach to non-take-up.Seit den 1960er Jahren befasst sich eine spezifische Literaturströmung der Soziologie des Wohlfahrtsstaates mit dem Phänomen des Nichtbezuges, d.h. mit Menschen, die Anspruch auf Sozialleistungen haben, diese aber nicht erhalten. In den letzten Jahren gewann diese Thematik zunehmend an Aufmerksamkeit und erreicht die politische Agenda, auch in der Schweiz. Wenn einige Menschen es vorziehen, ihre Rechte nicht in Anspruch zu nehmen, stellt es sowohl die Bedingungen für den Zugang zu Sozialleistungen als auch deren angemessene Ausgestaltung oder gar deren Legitimität in Frage. Was sagt der Nichtbezug über die vorherrschende Sozialpolitik aus? Können wir daraus etwas über die zugrunde liegenden Normen dieser Politik lernen? Wie kann der Nichtbezug aus der Perspektive von Betroffenen verstanden werden? Übernehmen die (potenziell) Anspruchsberechtigten die vorherrschenden Normen oder ist er ein Ausdruck des Widerstandes? Können öffentliche Dienste ihren Auftrag der Grundversorgung von vulnerablen Gruppen überhaupt erfüllen, wenn diese den Angeboten fernbleiben? Diese Sonderausgabe beginnt mit einer Einführung in das Thema des Nichtbezuges von Gesundheits- und Sozialleistungen und konzentriert sich dabei besonders auf den Forschungsstand in der Schweiz. Auf dieser Auslegeordnung aufbauend wird das Thema anschliessend analytisch weiterentwickelt. Damit wird eine Einordnung des Nichtbezuges möglich, die zur Analyse der Beziehung von BürgerInnen und Wohlfahrtsstaat genutzt werden kann. Die fünf Autoren des Sonderhefts tragen auf drei verschiedene Arten zu dieser neuen Forschungsagenda bei: indem sie die zeitliche Dimension des Nichtbezuges betonen; indem sie eine Sichtweise der Betroffenen als fähige und kritische Akteure unterstützen; und indem sie für einen systemischen und relationalen Ansatz des Nichtbezuges plädieren.Que nous apprend le non-recours sur les objectifs des politiques sociales et la manière dont ceux-ci sont perçus par les populations concernées ? Que nous dit-il des normes qui sous-tendent ces politiques, de leur approbation ou de leur rejet par les publics concernés? Que nous apprend-il sur le fonctionnement des services publics et leur capacité à atteindre et soutenir les populations précarisées ? Ce numéro spécial s'ouvre sur une introduction à la question du non-recours aux prestations sociales et de santé. Celle-ci dresse un bref état des savoirs, y compris en Suisse; sur cette base, elle propose de mobiliser l'analyse du non-recours pour éclairer la reconfiguration des relations entre l'Etat et les citoyen.e.s. Les cinq contributions qui suivent participent à ce nouvel agenda de recherche de trois manières: en mettant en évidence la dimension temporelle du non-recours; en considérant les publics des politiques sociales en tant qu'acteurs capables et critiques et en plaidant pour une approche systémique et relationnelle du non-recours