To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The objectives of the research described here were to describe the persistence of intramammary infections (IMI) caused by coagulase negative staphylococci (CNS) in goats using strain-typing, and to evaluate the relationship between species-specific CNS IMI and somatic cell score (SCS) at the udder-half level. Udder-half milk samples were collected from all 909 lactating goats (1817 halves; 1 blind half) in a single herd. Milk samples were cultured on Columbia blood agar, and 220 goats with at least one half yielding a single colony type CNS were enrolled for two additional half-level samplings at approximately 1-month intervals. Isolates were identified to the species level by matrix-assisted laser desorption-ionisation time-of-flight mass spectrometry or PCR amplification and partial sequencing of tuf or rpoB. An IMI was defined as persistent when ≥1 follow-up sample yielded the same species and strain as on Day 0 based on pulsed-field gel electrophoresis. A generalised mixed linear model was used to evaluate the odds of persistence as a function of CNS species. A mixed linear model was used to evaluate the relationship between IMI status on a given day and SCS. Among 192 IMI, 69.8% were persistent based on species and strain-type. Staphylococcus simulans IMI had higher odds of persistence than Staphylococcus arlettae IMI. In primiparous goats, Staphylococcus epidermidis IMI was associated with higher SCS than S. arlettae, Staphylococcus xylosus and ‘other CNS’ IMI. The differences detected in the present study between CNS species, with regard to persistence of IMI and association with SCS, highlight the need to study CNS at the species and strain level to understand the pathogenicity and epidemiology of CNS in goats.
The coffee berry borer (CBB), Hypothenemus hampei (Ferrari), is a multivoltine species closely associated with coffee crops worldwide, causing severe damage to the bean. In Mexico, as in all tropical regions, CBB survives during the inter-harvest period in residual berries on the ground or in dry berries remaining on the branches, and then disperses in search of the first suitable berries. In this study, we investigated how CBB dispersed from the first infested nodes during the fruiting period of Coffea canephora Pierre, which provides a favourable trophic level for this insect. Forty-five branches equally distributed in 15 coffee trees, with one infested node and four uninfested nodes, were selected. The branches were subjected to three treatments over nine weeks: 1) glue between nodes with full protection, 2) glue between nodes without protection, and 3) no glue and no protection. In addition, 45 CBB-free branches were selected and subjected to the same three treatments. CBB colonization can occur in three ways: 1) from an infested node to an uninfested node on the same branch, 2) from infested berries to uninfested berries within the nodes, 3) from branches to other branches. We also found that CBB dispersal between nodes of the same branches never occurred by walking but by flying. Thus, in this context of coffee berry development and ripening, and unlike the phenological situation of the inter-harvest period, CBB continuously travels very short distances, thus limiting its control.
We assess the gas-phase abundances of Si, C, and Fe from our recent measurements of Si++, C++, and Fe++ in the Orion Nebula by expanding on our earlier “blister” models. The Fe++ 22.9 μm line measured with the KAO yields Fe/H ~ 3 × 10−6 - considerably larger than in the diffuse ISM, where relative to solar, Fe/H is down by ~ 100. However, in Orion, Fe/H is still lower than solar by a factor ~ 10. The C and Si abundances are derived from new IUE high dispersion spectra of the C++ 1907, 1909 Å and Si++ 1883, 1892 Å lines. Gas-phase Si/C = 0.016 in the Orion ionized volume and is particularly insensitive to uncertainties in extinction and temperature structure. The solar value is 0.098. Gas-phase C/H = 3 × 10−4 and Si/H = 4.8 × 10−6. Compared to solar, Si is depleted by 0.135 in the ionized region, while C is essentially undepleted. This suggests that most Si and Fe resides in dust grains even in the ionized volume.
The synthesis and texturization processes of fluorinated surfaces by means of atmospheric plasma are investigated and presented through an integrated study of both the plasma phase and the resulting material surface. Three methods enhancing the surface hydrophobicity up to the production of super-hydrophobic surfaces are evaluated: (i) the modification of a polytetrafluoroethylene (PTFE) surface, (ii) the plasma deposition of fluorinated coatings and (iii) the incorporation of nanoparticles into those fluorinated films. In all the approaches, the nature of the plasma gas appears to be a crucial parameter for the desired property. Although a higher etching of the PTFE surface can be obtained with a pure helium plasma, the texturization can only be created if O2 is added to the plasma, which simultaneously decreases the total etching. The deposition of CxFy films by a dielectric barrier discharge leads to hydrophobic coatings with water contact angles (WCAs) of 115°, but only the filamentary argon discharge induces higher WCAs. Finally, nanoparticles were deposited under the fluorinated layer to increase the surface roughness and therefore produce super-hydrophobic hybrid coatings characterized by the nonadherence of the water droplet at the surface.
NASA's NuSTAR observatory is the first focusing hard X-ray telescope. Launched in June 2012, NuSTAR is sensitive in the 3–79 keV range with unprecedented ~17″ FWHM angular resolution above 12 keV, a result of its multilayer-coated optics and 10-m focal length. With its large effective area (900 cm2 at 10 keV), NuSTAR has point-source sensitivity ~100 times better than previous hard X-ray telescopes. Here we describe NuSTAR and its planned work on rotation-powered pulsars and magnetars during its nominal 2-yr baseline mission that has just commenced.
The objective was to study the multidimensional nature of the relationship between adult obesity (OB) and socio-economic status (SES), using comprehensive indices of SES taken separately or synthesised in an overall index. A nationally representative sample of adults aged 18–79 years was taken from the French second National Individual Survey on Food Consumption (INCA 2) dietary survey (2006–07). Weight and height were measured and OB defined as BMI ≥ 30 kg/m2. SES variables were reported in questionnaires and included occupation, education and characteristics of household wealth. Composite indices of SES (household wealth and overall SES indices) were computed by correspondence analysis, and relationships with OB were investigated with logistic regression analysis. In total, 11·8 (95 % CI 10·1, 13·4) % of French adults were obese, without significant difference by sex. While no significant relationship was observed in men, all SES indicators were inversely correlated to OB in women. Both education and the household wealth index were retained in the stepwise multivariate model, confirming that different socio-economic variables are not necessarily proxies of each other regarding the OB issue. On the other hand, ‘controlling for SES’ while including several measures of SES in multivariate models may lead to collinearity, and thus over-adjustment. A more integrative approach may be to derive a synthetic index by including the SES factors available in a given study. Beyond this methodological perspective, understanding how OB is related to the different dimensions of SES should help to target the more vulnerable groups and increase the effectiveness of prevention.
The purpose of this study was to develop a standardized tool for the assessment of surveillance systems on zoonoses and animal diseases. We reviewed three existing methods and combined them to develop a semi-quantitative assessment tool associating their strengths and providing a standardized way to display multilevel results. We developed a set of 78 assessment criteria divided into ten sections, representing the functional parts of a surveillance system. Each criterion was given a score according to the prescription of a scoring guide. Three graphical assessment outputs were generated using a specific combination of the scores. Output 1 is a general overview through a series of pie charts synthesizing the scores of each section. Output 2 is a histogram representing the quality of eight critical control points. Output 3 is a radar chart representing the level reached by ten system attributes. This tool was applied on five surveillance networks.
Our Present Understanding of the Mechanisms of the transformation of SiO films under treatments in O2 or Ar plasma at room T, is presented. RBS, IR absorption, XPS, RHEED and TEM techniques have been used to investigate the composition, the chemical and structural nature of the films after oxidizing or non oxidizing treatments. In O2 plasma, SiO is converted into Si02 by room T plasma anodization. The initial step of SiO oxidation, which is believed to be the transformation 2SiO→Si+SiO2, was studied in Ar plasma. We show that the as deposited SiO (not a mixture of Si and SiO2) is subject to disproportionate into the later compounds and that the effects of irradiation by low energy electrons at room T (plasma treatment) are similar to those observed for high T treatments (rapid thermal annealing).
Si 2p core-level spectroscopy is a unique tool to determine the chemical composition and spatial extension of the suboxide layer present at the Si/SiO2 interface. In the case of ultra-thin oxide films (thickness <10 Å), the high surface sensitivity provided by the tunability of synchrotron radiation allows the observation of four energetically well-separated oxidation states, generally attributed to a silicon atom with an increasing number of oxygen first neighbors, and hence often denoted Sin+(with n=1,…,4). After a brief review of two decades of XPS studies on the Si/SiO2 interface, we give an account of the recent debate concerning the possible contribution of the second oxygen neighbor shell to the chemical shift, which, if effective, would modify the picture of the interface. Then, we examine the benefit derived from the use of very high energy resolution (70 meV at hv=130 eV), and we try to determine, for this system, what are the limits of this spectroscopy. To illustrate the latter point, among various case studies (thermal oxides, room temperature adsorption etc.), we treat in more detail the case of the H-terminated Si(1 11) surface oxidized by atomic oxygen, and discuss our data in the light of previous XPS and vibrational spectroscopy studies.
Heavy ion irradiations in the electronic stopping power (Se.) regime have been performed in amorphous materials. Latent tracks have been observed in amorphous semiconductors (a-Ge, a-Si) and their radii have been deduced from a phenomenological analysis in an amorphous metallic alloy, in vitreous silica and “polymer” like amorphous carbon. A transient thermal model is developed describing the energy diffusion by the electron gas, by the atomic lattice and the energy exchange between the two subsystems. According to Fick's law, the classical equations of heat flow in the two subsystems (electrons and atoms) are numerically solved in a cylindrical geometry taking into account the temperature dependence of all the parameters. A simulation of annealing of nuclear collisions induced defects in crystalline iron allows to determine a local temperature. Electronic defect creation occurs when Se. increases and becomes larger than a threshold which is correlated with the appearance of a molten phase. Using such a criterion, the radii of latent tracks are reproduced in both a - Ge and a - Si with the same value of the electron-phonon coupling despite large differences in their lattice thermodynamic parameters. Such a model is applied to amorphous metallic alloy Fe85B15, vitreous silica and amorphous carbon.
The purpose of this paper is to study an optimal stopping problem with constraints for a Markov chain with general state space by using the convex analytic approach. The costs are assumed to be nonnegative. Our model is not assumed to be transient or absorbing and the stopping time does not necessarily have a finite expectation. As a consequence, the occupation measure is not necessarily finite, which poses some difficulties in the analysis of the associated linear program. Under a very weak hypothesis, it is shown that the linear problem admits an optimal solution, guaranteeing the existence of an optimal stopping strategy for the optimal stopping problem with constraints.
This work is concerned with the existence of an optimal control strategy for the long-run average continuous control problem of piecewise-deterministic Markov processes (PDMPs). In Costa and Dufour (2008), sufficient conditions were derived to ensure the existence of an optimal control by using the vanishing discount approach. These conditions were mainly expressed in terms of the relative difference of the α-discount value functions. The main goal of this paper is to derive tractable conditions directly related to the primitive data of the PDMP to ensure the existence of an optimal control. The present work can be seen as a continuation of the results derived in Costa and Dufour (2008). Our main assumptions are written in terms of some integro-differential inequalities related to the so-called expected growth condition, and geometric convergence of the post-jump location kernel associated to the PDMP. An example based on the capacity expansion problem is presented, illustrating the possible applications of the results developed in the paper.
Nursery areas of European sea bass (Dicentrarchus labrax, L.) were investigated from spring 2005 to summer 2006 in areas along the French Mediterranean coast of the Gulf of Lion. Nurseries were identified by the presence of settling individuals of sea bass and young juveniles. These nurseries represent different types of sheltered shallow habitats, both natural such as coastal lagoons, estuaries, and artificial such as marinas. Settlement occurred from April to June during both years. The number of settling individuals varied between sites from just a few individuals to several thousand. In one given site, settlement also varied between 2005 and 2006. The size distribution of sampled individuals revealed that several pulses arrived in each nursery. At this stage, sea bass already exhibited a strong orientation capacity but a limited swimming ability. The magnitude of sea bass settlement in marinas requires better environmental management of such artificial areas.
In this paper we obtain some ergodic properties and ergodic decompositions of a continuous-time, Borel right Markov process taking values in a locally compact and separable metric space. Initially, we assume that an invariant probability measure (IPM) μ exists for the process and, without making any further assumptions on the transition kernel, obtain some characterization results for the convergence of the expected occupation measure to a limit kernel. Under the same assumption, we present the so-called Yosida decomposition. Next, instead of assuming the existence of an IPM, we assume that the Markov process satisfies a certain condition, named the T'-condition. Under this condition it is shown that the Foster-Lyapunov criterion is necessary and sufficient for the existence of an IPM and that the process admits a Doeblin decomposition. Furthermore, it is shown that in this case the set of ergodic probability measures is countable and that every probability measure for the Markov process is nonsingular with respect to the transition kernel.
In this paper, it is shown that the Foster-Lyapunov criterion is sufficient to ensure the existence of an invariant probability measure for both discrete- and continuous-time Markov processes without any additional hypotheses (such as irreducibility).
In the previous design, the maximum drive radiation
temperature was 4 MK or 350 eV (Holstein 1996). Different
beam configurations gave roughly the same uniformity with
the NIF-size cavity. Our best configuration used four cones
of beams illuminating three rings. An integrated 2D simulation
pointed out that the symmetry was good enough to reach
a gain of ten. Two evolutions took place in the design
of our MJ laser. We moved from a capsule adapted to 4 MK
(L1000) to another one adapted to 3.5 MK (L1215) in order
to minimize the parametric instabilities (the cavity size
is almost the same). This new capsule also has a better
hydrostability according to the “classical modelling”
(Lindl 1995). The second evolution is a simplification
of the target chamber. We restricted ourselves to two major
configurations for indirect drive (two-ring and three-ring
configurations). Therefore, only three cones of beams are
necessary instead of five cones in the first design. Finally,
the number of holes in the chamber is 80 instead of 100.
During early stages of second language acquisition adult learners make frequent errors of lexical form. An experiment was performed to examine this effect in the laboratory. More and less fluent bilinguals in English and Spanish performed a translation recognition task in which they decided whether the second of two words was the correct translation of the first. In the critical conditions of the experiment the words were not correct translation equivalents, but related by lexical form (e.g., man-hambre (hunger) instead of man-hombre (man)) or by meaning (e.g., man-mujer (woman) instead of man-hombre (man)). Less fluent participants suffered more interference for form-related than for semantically related words relative to unrelated controls, but the reverse pattern held for more fluent participants. The results support a progression from reliance on word form to reliance on meaning with increasing proficiency in the second language. The performance of the more fluent bilinguals further suggests that the ability to retrieve semantic information directly for second-language words can potentially override some of the costs associated with lexical competition in languages that access shared lexical features.
The Rare-Earth Laves phases RE-Fe2 (RE represent the Rare-Earth) show large magnetostrictive properties, especially at room temperature. These materials are well characterized when in bulk form, but they have rarely been studied as thin films and one can expect some important effects due to epitaxial growth.
A few single crystal layers of RE-Fe2 have been studied (YFe2, TbFe2, DyFe2, ErFe2: and Dy0.7Tb0.3Fe2 known as Terfenol-D). The thickness of these different layers are between 5 and 20 nm and with  as a growth direction have been epitaxied. They have been deposited with a Molecular Beam Epitaxy (MBE) in an ultra high vacuum chamber. A  sapphire substrate is recovered by a  niobium buffer. The RE and the iron are then co-deposited on the substrate which is maintained at 500°C. Lastly, an Yttrium layer is deposited on the Rare Earth material at a temperature close to ambient.