Symmetry-breaking phase-transitions in highly concentrated semen

New experimental evidence of self-motion of a confined active suspension is presented. Depositing fresh semen sample in an annular shaped micro- fluidic chip leads to a spontaneous vortex state of the fluid at sufficiently large sperm concentration. The rotation occurs unpredictably clockwise or counterclockwise and is robust and stable. Furthermore, for highly active and concentrated semen, richer dynamics can occur such as self-sustained or damped rotation oscillations. Experimental results obtained with systematic dilution provide a clear evidence of a phase transition toward collective motion associated with local alignment of spermatozoa akin to the Vicsek model. A macroscopic theory based on previously derived Self-Organized Hydrodynamics (SOH) models is adapted to this context and provides predictions consistent with the observed stationary motion

Apnea of prematurity: from cause to treatment

Apnea of prematurity (AOP) is a common problem affecting premature infants, likely secondary to a “physiologic” immaturity of respiratory control that may be exacerbated by neonatal disease. These include altered ventilatory responses to hypoxia, hypercapnia, and altered sleep states, while the roles of gastroesophageal reflux and anemia remain controversial. Standard clinical management of the obstructive subtype of AOP includes prone positioning and continuous positive or nasal intermittent positive pressure ventilation to prevent pharyngeal collapse and alveolar atelectasis, while methylxanthine therapy is a mainstay of treatment of central apnea by stimulating the central nervous system and respiratory muscle function. Other therapies, including kangaroo care, red blood cell transfusions, and CO2 inhalation, require further study. The physiology and pathophysiology behind AOP are discussed, including the laryngeal chemoreflex and sensitivity to inhibitory neurotransmitters, as are the mechanisms by which different therapies may work and the potential long-term neurodevelopmental consequences of AOP and its treatment

The dynamics of finite size neutrally-buoyant particles in an isotropic turbulence

Un dispositif expérimental a été construit dans le but d'étudier la dynamique de particules de taille finie en suspension dans un écoulement turbulent isotrope à vitesse moyenne faible. Les caractéristiques de la turbulence ont été mesurée, et les échelles pertinentes de temps et d'espace ont été mesurées. Des particules de tailles millimétriques ont ensuite été ajoutées avec une technique de suivi. Les statistiques de vitesses des deux phases ont été calculées et comparées

Evaluation of three competitive ELISAs and a fluorescence polarisation assay for the diagnosis of bovine brucellosis.

&lt;p&gt;Bovine brucellosis is an infectious disease of worldwide public health and economic importance. The usual tests for the diagnosis of this disease include the Rose-Bengal test (RBT), complement fixation test (CFT), serum agglutination test (SAT) and indirect ELISA. New tests such as competitive ELISAs (C-ELISA) and fluorescence polarisation assay (FPA) have been developed. However, C-ELISA may correspond to different protocols and a wide variation may exist in their diagnostic performance. The aim of this study was to evaluate three commercially available C-ELISA kits (C-ELISA1-3) and FPA for the diagnosis of bovine brucellosis and compare test performance with RBT, CFT, indirect ELISA and FPA. Sera submitted to EU laboratories in 2011 from 5111 adult cattle were tested. Individual test sensitivities (Se) and specificities (Sp) were estimated. Threshold assessment using the receiver operating characteristic method was also performed. The most sensitive tests were FPA (99.0%; 95% confidence interval [CI], 97.9-100%), C-ELISA1 (98.4%; 95% CI, 97.0-99.8%) and RBT (97.7%; 95% CI, 95.9-99.3%). The most specific tests were CFT (99.98%; 95% CI, 99.93-100%), SAT (99.98%; 95% CI, 99.93-100%) and RBT (99.89%; 95% CI, 99.79-99.99%). Among the new tests, none of the three C-ELISA kits studied could be recommended as a single screening test because of their low specificity, especially when used in a herd. C-ELISA3 could not be recommended as confirmatory test on individual animals to determine whether false positive serological test results had occurred.&lt;/p&gt;</p