Generalized model of blockage in particulate flow limited by channel carrying capacity

We investigate stochastic models of particles entering a channel with a random time distribution. When the number of particles present in the channel exceeds a critical value $N$, a blockage occurs and the particle flux is definitively interrupted. By introducing an integral representation of the $n$ particle survival probabilities, we obtain exact expressions for the survival probability, the distribution of the number of particles that pass before failure, the instantaneous flux of exiting particle and their time correlation. We generalize previous results for $N=2$ to an arbitrary distribution of entry times and obtain new, exact solutions for $N=3$ for a Poisson distribution and partial results for $N\ge 4$.Comment: 13 pages, 9 figure

Genetic Changes Over Breeding Generations of \u3cem\u3eFestulolium\u3c/em\u3e

Festulolium hybrids are a valuable breeding source for tolerance to abiotic stress and to make grass more persistent under drought and in cold environments. In 2004, the EU Commission enlarged the definition of Festulolium which may now include all hybrids between Lolium sp. and Festuca sp. and not only those between L. multiflorum and F. pratensis. We here report allele frequencies at two unlinked PCR-based marker loci in populations derived from tetraploid (2n=4x=28) L. multiflorum x F. glaucescens hybrids where breeding history enables us to test the effects of selection vs that of genetic drift

Experimental study of granular surface flows via a fast camera: a continuous description

Depth averaged conservation equations are written for granular surface flows. Their application to the study of steady surface flows in a rotating drum allows to find experimentally the constitutive relations needed to close these equations from measurements of the velocity profile in the flowing layer at the center of the drum and from the flowing layer thickness and the static/flowing boundary profiles. The velocity varies linearly with depth, with a gradient independent of both the flowing layer thickness and the static/flowing boundary local slope. The first two closure relations relating the flow rate and the momentum flux to the flowing layer thickness and the slope are then deduced. Measurements of the profile of the flowing layer thickness and the static/flowing boundary in the whole drum explicitly give the last relation concerning the force acting on the flowing layer. Finally, these closure relations are compared to existing continuous models of surface flows.Comment: 20 pages, 11 figures, submitted to Phys. FLuid

Nymphaea kakaduensis (Nymphaeaceae), a new species from the northern portion of the Northern Territory, Australia

Nymphaea kakaduensis C. B. Hellq., A. Leu & M. L. Moody (Nymphaeaceae) is described from Kakadu National Park, Northern Territory. This new species is endemic to the “Top End” of the Northern Territory and was formerly included in N. violacea Lehm. The distinct floral form of N. kakaduensis of having generally smaller flowers with blunt-tipped petals and different coloration than N. violacea instigated a genetic study of taxa from the region. The cpDNA trnL (UAA) - trnF (GAA) intergenic spacer region was sequenced from samples from across northern Australia and a haplotype network analysis was conducted. Plants from populations that had the distinct floral form of N. kakaduensis are found to be genetically distinct from N. violacea in northern Australia sharing 4 SNPs and a notable 23 bp indel in the cpDNA intergenic spacer region to support the morphological attributes and species designation

Simian immunodeficiency virus infection in wild-caught chimpanzees from Cameroon

Simian immunodeficiency viruses (SIVcpz) infecting chimpanzees (Pan troglodytes) in west central Africa are the closest relatives to all major variants of human immunodeficiency virus type 1 ([HIV-1]; groups M, N and O), and have thus been implicated as the source of the human infections; however, information concerning the prevalence, geographic distribution, and subspecies association of SIVcpz still remains limited. In this study, we tested 71 wild-caught chimpanzees from Cameroon for evidence of SIVcpz infection. Thirty-nine of these were of the central subspecies (Pan troglodytes troglodytes), and 32 were of the Nigerian subspecies (Pan troglodytes vellerosus), as determined by mitochondrial DNA analysis. Serological analysis determined that one P. t. troglodytes ape (CAM13) harbored serum antibodies that cross-reacted strongly with HIV-1 antigens; all other apes were seronegative. To characterize the newly identified virus, 14 partially overlapping viral fragments were amplified from fecal virion RNA and concatenated to yield a complete SIVcpz genome (9,284 bp). Phylogenetic analyses revealed that SIVcpzCAM13 fell well within the radiation of the SIVcpzPtt group of viruses, as part of a clade including all other SIVcpzPtt strains as well as HIV-1 groups M and N. However, SIVcpzCAM13 clustered most closely with SIVcpzGAB1 from Gabon rather than with SIVcpzCAM3 and SIVcpzCAM5 from Cameroon, indicating the existence of divergent SIVcpzPtt lineages within the same geographic region. These data, together with evidence of recombination among ancestral SIVcpzPtt lineages, indicate long-standing endemic infection of central chimpanzees and reaffirm a west central African origin of HIV-1. Whether P. t. vellerosus apes are naturally infected with SIVcpz requires further study

The birds of the Loyalty Islands (New Caledonia): census, ecological and biogeographical issues

The avifauna of the Loyalty Islands comprises 62 species, including 14 breeding or erratic seabirds, 5 migratory birds, 7 herons, ducks and rails, 4 birds of prey, 28 indigenous land breeders (belonging to 33 subspecies) and 2 species introduced from the Grande Terre (main island of New Caledonia). Six species are endemic: 3 on the Grande Terre and in the Loyalty Islands (New Caledonian Friarbird Philemon diemenensis, Green-backed White-eye Zosterops xanthochrous, Striated Starling Aplonis striatus) and 3 only found in the Loyalty Islands (Ouvea Parakeet Eunymphicus uvaeensis, Large Lifou White-eye Zosterops inornatus and Small Lifou White-eye Z. minutus). Eunymphicus is an endemic genus of New Caledonia. Eight subspecies are endemic to both the Grande Terre and the Loyalty Islands and 11 are exclusive of the Loyalty Islands. Of the 24 taxa whose geographical origin could be identified, 58% are identical or similar to those on the Grande Terre, 105 km away, and 42% have affinities with birds in Vanuatu, twice as far away (225 km). The paths of cyclones could explain the specific influence of Vanuatu. The correlation between the islands’land area and the number of species that have successfully settled is very close (r = 0.97) and confirms this biogeographical standard. The land breeding species frequencies vary, with rare localized species limited to some islands (Bluefaced Parrotfinch Erythrura trichroa, Ouvea Parakeet), or possibly extinct (Island Thrush Turdus poliocephalus) and others whose frequency varies widely from place to place (Fan-tailed Cuckoo Cacomantis flabelliformis, Gerygone Gerygone flavolateralis, Silvereye Zosterops lateralis), while others show high (Red-bellied Fruit-Dove Ptilinopus greyii), average (Melanesian Flycatcher Myiagra caledonica, Sacred Kingfischer Todiramphus sanctus) or low (Emerald Dove Chalcophaps indica) frequencies that remain comparable between these islands. The species ecology has been determined with some species associated with wide forests, e.g. the Ouvea Parakeet, while others are typical of the open settings. The threats onto this avifauna are mainly linked to habitat destruction and the impact of introduced species. A specific effort should be made to ensure the protection of populations of that species for which there is the greatest concern, i.e. the Ouvea ParakeetL'avifaune des Loyauté comprend 62 espèces, dont 14 marines nicheuses ou erratiques, 5 migratrices, 7 hérons, canards et râles, 4 rapaces/chouette, 28 oiseaux terrestres nicheurs indigènes (appartenant à 33 sous-espèces) et 2 espèces introduites de Grande Terre. Six espèces sont endémiques à l'archipel néo-calédonien: 3 présentes à la fois en Grande Terre et aux Loyauté: Polochion moine Philemon diemenensis, Zostérops à dos vert Zosterops xanthochrous, Stourne des Loyauté Aplanis striatus et 3 pour les seules Loyauté: Perruche d'Ouvéa Eunymphicus uvaeensis, Zostérops de Lifou Zosterops inornatus et Zostérops minute Z. minutus. Eunymphicus est un genre endémique de Nouvelle-Calédonie. Huit sous-espèces sont endémiques à la fois de Grande Terre et des Loyauté et 11 sont exclusives des Loyauté. Sur 24 taxons dont l'origine géographique peut être établie, 58 % sont identiques ou proches de ceux de Grande Terre distante de 105 km, et 42 % ont des affinités avec des oiseaux du Vanuatu, deux fois plus éloigné (225 km). La trajectoire des cyclones pourrait expliquer cette influence ni-vanuatu particulière. La corrélation entre la surface des îles et le nombre d'espèces qui y ont réussi leur implantation est très étroite (r = 0,97) et vérifie bien cette règle de la biogéographie. La fréquence des espèces terrestres nicheuses est variable, avec des espèces rares et localisées, limitées à certaines îles (Diamant de Kittlitz Erythrura trichroa, Perruche d'Ouvéa) et qui ont peut-être disparu (Merle des Iles Turdus poliocephalus), d'autres dont la fréquence est très inégalement répartie (Coucou à éventail Cacomantis flabelliformis, Gérygone Gerygone flavolateralis, Zostérops à dos noir Zosterops lateralis), d'autres enfin aux fréquences élevées (Ptilope de Grey Ptilinopus greyii), moyennes (Monarque Myiagra caledonica, Martin-chasseur Todiramphus sanctus) ou faibles (Colombine turvert Chalcophaps indica), mais comparables entre les îles. L'écologie des espèces a pu être précisée avec des espèces inféodées aux grandes forêts, parmi lesquelles la Perruche d'Ouvéa, et des espèces typiques des milieux ouverts. Les menaces pesant sur cette avifaune sont essentiellement liées aux destructions d'habitat et à l'impact des espèces introduites. Un effort particulier doit être consenti pour sécuriser les populations de l'espèce dont le statut est le plus préoccupant: la Perruche d'Ouvéa

Interest of pet imaging in multiple myeloma

The interest of 18Fluoro-deoxyglucose (FDG) positron emission tomography (PET) imaging in the management of patients with multiple myeloma (MM) for the workup at diagnosis and for therapeutic evaluation has recently been demonstrated. FDG-PET is a powerful imaging tool for bone lesions detection at initial diagnosis with high sensitivity and specificity values. The independent pejorative prognostic value on progression-free survival (PFS) and overall survival (OS) of baseline PET-derived parameters (presence of extra-medullary disease (EMD), number of focal bone lesions (FLs), and maximum standardized uptake values [SUVmax]) has been reported in several large independent prospective studies. During therapeutic evaluation, FDG-PET is considered as the reference imaging technique, because it can be performed much earlier than MRI which lacks specificity. Persistence of significant FDG uptake after treatment, notably before maintenance therapy, is an independent pejorative prognostic factor, especially for patients with a complete biological response. So FDG-PET and medullary flow cytometry are complementary tools for detection of minimal residual disease before maintenance therapy. However, the definition of PET metabolic complete response should be standardized. In patients with smoldering multiple myeloma, the presence of at least one hyper-metabolic lytic lesions on FDG-PET may be considered as a criterion for initiating therapy. FDG-PET is also indicated for initial staging of a solitary plasmacytoma so as to not disregard other bone or extra-medullary localizations. Development of nuclear medicine offer new perspectives for MM imaging. Recent PET tracers are willing to overcome limitations of FDG. (11)C-Methionine, which uptake reflects the increased protein synthesis of malignant cells seems to correlate well with bone marrow infiltration. Lipid tracers, such as Choline or acetate, and some peptide tracers, such as (68) Ga-Pentixafor, that targets CXCR4 (chemokine receptor-4, which is often expressed with high density by myeloma cells), are other promising PET ligands. 18F-fludarabine and immuno-PET targeting CD138 and CD38 also showed promising results in preclinical models

The Paradoxical Effects of Chronic Intra-Amniotic Ureaplasma parvum Exposure on Ovine Fetal Brain Development

Chorioamnionitis is associated with adverse neurodevelopmental outcomes in preterm infants. Ureaplasma spp. are the microorganisms most frequently isolated from the amniotic fluid of women diagnosed with chorioamnionitis. However, controversy remains concerning the role of Ureaplasma spp. in the pathogenesis of neonatal brain injury. We hypothesize that re-exposure to an inflammatory trigger during the perinatal period might be responsible for the variation in brain outcome of preterms following Ureaplasma driven chorioamnionitis. To investigate these clinical scenarios, we performed a detailed multi-modal study in which ovine neurodevelopmental outcomes were assessed following chronic intra-amniotic Ureaplasma parvum (UP) infection, either alone or combined with subsequent lipopolysaccharide (LPS) exposure. We show that chronic intra-amniotic UP exposure during the second trimester provoked a decrease of astrocytes, increased oligodendrocyte numbers and elevated 5-methylcytosine levels. In contrast, short-term LPS exposure before preterm birth induced increased microglial activation, myelin loss, elevation of 5-hydroxymethylcytosine levels and lipid profile changes. These LPS-induced changes were prevented by chronic pre-exposure to UP (preconditioning). These data indicate that chronic UP exposure provokes dual effects on preterm brain development in utero. On one hand, prolonged UP exposure causes detrimental cerebral changes which may predispose to adverse postnatal clinical outcomes. On the other, chronic intra-amniotic UP exposure preconditions the brain against a second inflammatory hit. This study demonstrates that microbial interactions, timing and duration of inflammatory insults will determine the effects on the fetal brain. Therefore, this study helps to understand the complex and diverse postnatal neurological outcomes following UP driven chorioamnionitis

FtsK-Dependent Dimer Resolution on Multiple Chromosomes in the Pathogen Vibrio cholerae

Unlike most bacteria, Vibrio cholerae harbors two distinct, nonhomologous circular chromosomes (chromosome I and II). Many features of chromosome II are plasmid-like, which raised questions concerning its chromosomal nature. Plasmid replication and segregation are generally not coordinated with the bacterial cell cycle, further calling into question the mechanisms ensuring the synchronous management of chromosome I and II. Maintenance of circular replicons requires the resolution of dimers created by homologous recombination events. In Escherichia coli, chromosome dimers are resolved by the addition of a crossover at a specific site, dif, by two tyrosine recombinases, XerC and XerD. The process is coordinated with cell division through the activity of a DNA translocase, FtsK. Many E. coli plasmids also use XerCD for dimer resolution. However, the process is FtsK-independent. The two chromosomes of the V. cholerae N16961 strain carry divergent dimer resolution sites, dif1 and dif2. Here, we show that V. cholerae FtsK controls the addition of a crossover at dif1 and dif2 by a common pair of Xer recombinases. In addition, we show that specific DNA motifs dictate its orientation of translocation, the distribution of these motifs on chromosome I and chromosome II supporting the idea that FtsK translocation serves to bring together the resolution sites carried by a dimer at the time of cell division. Taken together, these results suggest that the same FtsK-dependent mechanism coordinates dimer resolution with cell division for each of the two V. cholerae chromosomes. Chromosome II dimer resolution thus stands as a bona fide chromosomal process

Specificity and origin of the stability of the sr isotopic ratio in champagne wines

The 87Sr/86Sr ratio of 39 Champagnes from six different brands, originating from the whole “Appellation d’Origine Contrôlée” (AOC) Champagne was analyzed to establish a possible relation with the geographical origin. Musts (i.e., grape juice) and base wines were also analyzed to study the evolution of the Sr isotopic ratio during the elaboration process of sparkling wine. The results demonstrate that there is a very homogeneous Sr isotopic ratio (87 Sr/86 Sr = 0.70812, n = 37) and a narrow span of variability (2? = 0.00007, n = 37). Moreover, the Sr concentrations in Champagnes have also low variability, which can be in part explained by the homogeneity of the bedrock in the AOC Champagne. Measurements of the87 Sr/86 Sr ratio from musts and base wines show that blending during Champagne production plays a major role in the limited variability observed. Further, the87 Sr/86 Sr of the musts were closely linked to the87 Sr/86 Sr ratio of the vineyard soil. It appears that the87 Sr/86 Sr of the product does not change during the elaboration process, but its variability decreases throughout the process due to blending. Both the homogeneity of the soil composition in the Champagne AOC and the blending process during the wine making process with several blending steps at different stages account for the unique and stable Sr isotopic signature of the Champagne wines.Centre de Spectrometrie de Masse pour les Sciences de la Réactivité et de Spéciatio