906 research outputs found
Nano-building block based-hybrid organic–inorganic copolymers with self-healing properties
New dynamic materials, that can repair themselves after strong damage, have been designed by hybridization of polymers with structurally well-defined nanobuilding units. The controlled design of cross-linked poly(n-butyl acrylate) (pBuA) has been performed by introducing a very low amount of a specific tin oxo-cluster. Sacrificial domains with non-covalent interactions (i.e. ionic bonds) developed at the hybrid interface play a double role. Such interactions are strong enough to cross-link the polymer, which consequently exhibits rubber-like elasticity behavior and labile enough to enable, after severe mechanical damage, dynamic bond recombination leading to an efficient healing process at room temperature. In agreement with the nature of the reversible links at the hybrid interface, the healing process can speed up considerably with temperature. 1H and 119Sn PFG NMR has been used to evidence the dynamic nature of these peculiar cross-linking nodes
A simple, inexpensive trap for capturing parrots and other cavity nesting birds
This is the published version: Berg, M. L. and Ribot, R. F. H. 2008, A simple, inexpensive trap for capturing parrots and othe
Obliteration study of lambdatic and obelionic region sutures in ruminant, carnivores and hominids
The morphology of Orce cranial fragment VM-0 is contrasted with the fronto-parietal region in artiodactyls, and the obelionic region in carnivores and primates including hominids. Sutural development at obelion is compared in those taxa throughout the growth period up to the onset of sutural obliteration, and ontogenetic differences between non-primates and primates lead us to conclude that the configuration in VM-0 more resembles that found in hominids than in artiodactyls or carnivores. Moreover, cranial capacity for VM-0 is estimated at >470cm3, comparable to Plio Pleistocene hominids, but greater than in young equids.La morfología del fragmento cranial de Orce (VM-0) se contrasta con la región fronto-parietal de los artiodáctilos y con la región obélica de los carnívoros y primates incluyendo los homínidos. Se compara en estos taxones, el desarrollo de las suturas en esta región a lo largo del periodo de crecimiento hasta que ocurre la obliteración de las mismas. Las diferencias ontogenéticas entre no primates y primates nos permiten concluir que la anatomía de VM-0 es más próxima a los hominidos que a la de los artiodáctilos y carnívoros. Se estima que la capacidad craneana de VM-0 tiene que ser > 470 cm3, comparable a la de los homínidos del Plio-Pleistoceno y mayor que la de los équidos juveniles
Proximate cues to phases of movement in a highly dispersive waterfowl, Anas superciliosa
BACKGROUND: Waterfowl can exploit distant ephemeral wetlands in arid environments and provide valuable insights into the response of birds to rapid environmental change, and behavioural flexibility of avian movements. Currently much of our understanding of behavioural flexibility of avian movement comes from studies of migration in seasonally predictable biomes in the northern hemisphere. We used GPS transmitters to track 20 Pacific black duck (Anas superciliosa) in arid central Australia. We exploited La Niña conditions that brought extensive flooding, so allowing a rare opportunity to investigate how weather and other environmental factors predict initiation of long distance movement toward freshly flooded habitats. We employed behavioural change point analysis to identify three phases of movement: sedentary, exploratory and long distance oriented movement. We then used random forest models to determine the ability of meteorological and remote sensed landscape variables to predict initiation of these phases. RESULTS: We found that initiation of exploratory movement phases is influenced by fluctuations in local weather conditions and accumulated rainfall in the landscape. Initiation of long distance movement phases was found to be highly individualistic with minor influence from local weather conditions. CONCLUSIONS: Our study reveals how individuals utilise local conditions to respond to changes in resource distribution at broad scales. Our findings suggest that individual movement decisions of dispersive birds are informed by the integration of multiple weather cues operating at different temporal and spatial scales
Two deciduous human molars from the early Pleistocene deposits of Barranco León (Orce, Spain)
Recently Toro-Moyano et al. (2013) reported a deciduous tooth from Barranco Leo´n (Spain; BL02-J54-100) and claimed it to be the oldest human fossil in Europe. In that paper, the authors suggest that a previously reported human molar fragment from the same site (BL5-0) was not human but a deciduous molar of Hippopotamus found out of stratigraphic context. Here, we show the stratigraphic and spatial position of BL5-0, and we separate it from deciduous teeth of Hippopotamus. We conclude that two human deciduous molars have been discovered at the Barranco Leo´n site. Both teeth were found 9 meters apart, have a similar size, are heavily worn on the occlusal surface, have a nearly identical interstitial contact facet, and in both cases the roots are practically missing due to resorption. These similarities and the proximity of the finds suggest that both molars probably belonged to the same individua
“Chimie douce”: A land of opportunities for the designed construction of functional inorganic and hybrid organic-inorganic nanomaterials
Abstract“Chimie douce” based strategies allow, through the deep knowledge of materials chemistry and processing, the birth of the molecular engineering of nanomaterials. This feature article will highlight some of the main research accomplishments we have performed during the last years. We describe successively the design and properties of: sol–gel derived hybrids, Nano Building Blocks (NBBs) based hybrid materials, nanostructured porous materials proceeds as thin films and ultra-thin films, aerosol processed mesoporous powders and finally hierarchically structured materials. The importance of the control of the hybrid interfaces via the use of modern tools as DOSY NMR, SAXS, WAXS, Ellipsometry that are very useful to evaluate in situ the hybrid interfaces and the self-assembly processes is emphasized. Some examples of the optical, photocatalytic, electrochemical and mechanical properties of the resulting inorganic or hybrid nanomaterials are also presented
Ceftriaxone-Resistant Salmonella Infection Acquired by a Child from Cattle
Background The emergence of resistance to antimicrobial agents within the salmonellae is a worldwide problem that has been associated with the use of antibiotics in livestock. Resistance to ceftriaxone and the fluoroquinolones, which are used to treat invasive salmonella infections, is rare in the United States. We analyzed the molecular characteristics of a ceftriaxone-resistant strain of Salmonella enterica serotype typhimurium isolated from a 12-year-old boy with fever, abdominal pain, and diarrhea. Methods We used pulsed-field gel electrophoresis and analysis of plasmids and β-lactamases to compare the ceftriaxone-resistant S. enterica serotype typhimurium from the child with four isolates of this strain obtained from cattle during a local outbreak of salmonellosis. Results The ceftriaxone-resistant isolate from the child was indistinguishable from one of the isolates from cattle, which was also resistant to ceftriaxone. Both ceftriaxone-resistant isolates were resistant to 13 antimicrobial agents; all but one of the resistance determinants were on a conjugative plasmid of 160 kb that encoded the functional group 1 β-lactamase CMY-2. Both ceftriaxone-resistant isolates were closely related to the three other salmonella isolates obtained from cattle, all of which were susceptible to ceftriaxone. Conclusions This study provides additional evidence that antibiotic-resistant strains of salmonella in the United States evolve primarily in livestock. Resistance to ceftriaxone, the drug of choice for invasive salmonella disease, is a public health concern, especially with respect to children, since fluoroquinolones, which can also be used to treat this disease, are not approved for use in children
From Pig to Pacifier: Chitterling-Associated Yersiniosis Outbreak among Black Infants
In this case-control study of Yersinia enterocolitica infections among black infants, chitterling preparation was significantly associated with illness (p<0.001). Of 13 samples of chitterlings tested, 2 were positive for Yersinia intermedia and 5 for Salmonella. Decontamination of chitterlings before sale with methods such as irradiation should be strongly considered
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