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Early nutrition may have long-lasting metabolic impacts in adulthood. Even though breast milk is the gold standard, most infants are at least partly formula-fed. Despite obvious improvements, infant formulas remain perfectible to reduce the gap between breastfed and formula-fed infants. Improvements such as reducing the protein content, modulating the lipid matrix and adding prebiotics, probiotics and synbiotics, are discussed regarding metabolic health. Numerous questions remain to be answered on how impacting the infant formula composition may modulate the host metabolism and exert long-term benefits. Interactions between early nutrition (composition of human milk and infant formula) and the gut microbiota profile, as well as mechanisms connecting gut microbiota to metabolic health, are highlighted. Gut microbiota stands as a key actor in the nutritional programming but additional well-designed longitudinal human studies are needed.
The photochemistry of CO and its isotoplogues affects the structure and evolution of many astronomical environments, including interstellar clouds, circumstellar disks around newly formed stars, and the envelopes surrounding highly evolved stars. When in the presence of a strong ultraviolet field, the primary destruction mechanism for interstellar and circumstellar CO is photodissociation, which is entirely governed by discrete line absorption into predissociating levels in the wavelength range 91.2 to 111.8 nm. Because the CO spectrum consists primarily of resolved line features, self-shielding effects in high-column density environments can lead to strong isotopic fractionation signatures in both CO and elemental oxygen and carbon; for example, CO self-shielding in the solar nebula has been invoked to explain the unusual oxygen isotope ratios observed in the earliest solar system condensates, viz. calcium-aluminum inclusions (CAIs) in primitive meteorites.
Malawi is under heavy pressure for land by an increasing human population, and there is little natural habitat left outside gazetted wildlife and forest reserves. Widespread collecting of birds in Malawi’s small protected rain forests by the National Museum of Malawi in conjunction with Western academic institutions has been taking place almost yearly since 2001 and has continued until at least 2011. The collection of specimens, although often a contentious issue, does have scientific value but should be undertaken in a limited way with careful evaluation of the populations from which birds are being taken. We consider that the numbers collected are likely to pose a threat to some bird populations in view of their isolation and the slow turn-over rates of breeding individuals. Collecting has been carried out in some of the same reserves two or three times within a few years. Examples are given of very small populations in Malawi and adjacent Mozambique where the slightest off-take would be very dangerous. Many species have been collected during their breeding season, which we find both wasteful and unethical. Several of the species collected occur in no more than one or two reserves today in Malawi and in such instances we recommend their complete protection. We are also concerned about the example presented to the local communities, reserve wardens and young conservation biologists by the off-take of hundreds of birds in official reserves which were primarily set up for the protection of wildlife.
Objectif : comparer la dose délivrée aux patients et la qualité d’image
en routine clinique lors de la réalisation d’un scanner abdominal ne disposant pas des
techniques de reconstructions itératives (RI) par rapport à un examen réalisé sur un
scanner disposant des RI. Matériels et méthodes : il s’agit d’une étude
rétrospective incluant 30 patients ayant eu deux examens abdominaux sur un scanner 40
coupes (TDM40) et sur un scanner 256 coupes avec RI (TDM256). Les patients, suivis pour
une pathologie abdominale chronique, ont eu un examen de même indication sur chaque
scanner avec un protocole comprenant une phase abdomino-pelvienne au temps portal. La
longueur d’acquisition, la dose efficace et le Produit Dose Longueur (PDL) ainsi que des
évaluations quantitatives et qualitatives de l’image ont été comparés. Résultats
: la dose efficace moyenne pour un examen était de 17,3 mSv avec le TDM40 (PDL :
1019 mGy.cm) contre 11,1 mSv avec le TDM256 (PDL : 654 mGy.cm) soit une réduction de 35,8 % (p < 0,001). Les longueurs d’acquisitions et l’évaluation quantitative étaient comparables dans les deux groupes. L’évaluation qualitative était
légèrement supérieure sur le TDM40 mais aucun examen n’a été considéré comme sous-optimal.
Conclusion : l’utilisation d’un scanner équipé de RI permet une
réduction significative de la dose efficace tout en préservant une bonne qualité d’image.
Interstellar water ice is mainly amorphous, but the nature of its morphology still
remains poorly known. The experimental study described in this work focuses on how
relevant changes of the ice morphology result from atomic hydrogen exposure and subsequent
recombination. We show that there is an exponential decrease in the porosity of the
amorphous water ice sample following hydrogen-atom irradiation. These and other laboratory
results lead us to suggest that water ice in space is almost certainly amorphous and
We explore experimentally the formation of water molecules from O2 and D atoms
on bare grains composed of amorphous silicates analogous to those in diffuse interstellar
clouds. We provide the fractions of D2O and D2O2
molecules formed on the silicate surface held at 10 K from the O2 + D pathway
using RAIRS and TPD techniques. For comparison, we also study the formation of water
molecules on surfaces covered with amorphous water ice representing the dense clouds.
We present a combined theoretical and experimental study of the adsorption of two pairs
of organic isomers, (i) acetic acid AA (CH3COOH) and methyl
formate MF (HCOOCH3), and (ii) ethanol EtOH
(CH3CH2OH) and dimethyl ether DME (CH3OCH3),
onto crystalline water ice surfaces at low temperatures. Both approaches show that, for
each pair, the most stable isomer from a thermodynamical point of view,
i.e. AA and EtOH, is
also the one which is the more tightly bound to the water ice surface compared to the less
stable isomers (MF and DME). This finding, which can be explained by the ability of AA or
EtOH to efficiently interact with the ice surface via hydrogen bondings, may have
important consequences in an astrophysical context, since it could explain why the most
stable isomer is not the most abundant observed in the interstellar gas phase.
The development of functional-structural plant models has opened interesting perspectives
for a better understanding of plant growth as well as for potential applications in
breeding or decision aid in farm management. Parameterization of such models is however a
difficult issue due to the complexity of the involved biological processes and the
interactions between these processes. The estimation of parameters from experimental data
by inverse methods is thus a crucial step. This paper presents some results and
discussions as first steps towards the construction of a general framework for the
parametric estimation of functional-structural plant models. A general family of models of
Carbon allocation formalized as dynamic systems serves as the basis for our study. An
adaptation of the 2-stage Aitken estimator to this family of model is introduced as well
as its numerical implementation, and applied in two different situations: first a
morphogenetic model of sugar beet growth with simple plant structure, multi-stage and
detailed observations, and second a tree growth model characterized by sparse observations
and strong interactions between functioning and organogenesis. The proposed estimation
method appears robust, easy to adapt to a wide variety of models, and generally provides a
satisfactory goodness-of-fit. However, it does not allow a proper evaluation of estimation
uncertainty. Finally some perspectives opened by the theory of hidden models are
The reaction of H2 with undoped silica core fibers was evaluated by means of “in situ” spectral loss measurements. Drawing induced loss peaks at 0.63 μm decreased rapidly upon exposure to hydrogen. Simultaneous loss increases at 1.39 and 1.53 μm suggest that H2 reacts at nonbridging oxygens and oxygen vacancies created during the drawing process, forming SiOH and SiH. The 1.53 μm SiH peak slowly decayed after its initially rapid growth, indicating that SiH is not thermodynamically stable in silica. The concentration of drawing induced defects is estimated to be on the order of 100 ppb, based on the time required for H2 to diffuse to the fiber core. The appearance of peaks at 1.45 μm suggests that HF is formed by reaction of H2 in the fluorine doped cladding of the fibers.
Permanent X(2) gratings can be written in doped silica fibers by coherent irradiation with light at ω and 2ω. The X(2) gratings give rise to phase-matched second harmonic generation (SHG), i.e. subsequent irradiation of the prepared fiber with light at ω results in an output at 2ω. The efficiency with which the gratings can be written depends on the nature and concentration of defect states induced by dopants in the, glass. We present results for fibers doped with Ge and rare earth ions and discuss the implications of our results for the various mechanisms that have been proposed to explain photoinduced SHG in fibers.
Organic based ion selective resins have some similar attributes: case of synthesis, high metal ion complexation ability, and flexibility for different nuclear waste management applications. For most chelating polymers, the ligand is deemed to be of primary importance for the interaction with the targeted metal ion. The role of the polymer matrix is usually ignored. For ion specific resins, the polymer structure is formed to a specific metal ion. Using the molecular imprinting technique, resins can be formed with functional groups and cavities for a target metal ion. Ion selective resins have been developed for the separation of Cs. The methods and concepts used for the development of the Cs specific resins have been applied to the development of selective resins for Eu (a trivalent actinide model). The resulting resins are characterized by FTIR spectroscopy, moisture regain, and ion exchange capacity. The incorporation of 8-hydroxyquinoline into the resin increases selectivity for Eu over La. The results for the Eu study indicate ion specific resins can be developed for the separation of trivalent actinides from nuclear waste.
The topic of reliability of UV-induced fiber gratings is reviewed. Approaches to assess and predict changes in optical properties of fiber gratings due to thermal decay of refractive index modulation are presented and compared. The mastercurve/demarcation energy diagram approach is shown to be a powerful and general method for the purpose. The process of thermal stabilization to obtain gratings with superior stability is delineated. It is shown that the mastercurve approach could be used to analyze other reliability problems such as in predicting hydrogen-induced losses in fibers.
For every mill the ideal roll can be considered as one that can be used in a mill stand indefinitely. Unfortunately for the roll user, such ideal rolls do not exist. One major reason for work roll changes (planned or unplanned) is “wear”. In the context of cold rolling and temper rolling, “wear” primarily refers to loss of roughness and/or surface texture. Another limitation to roll performance is the fact that mill incidents – minor as well as major incidents – inflict damage on the work rolls, requiring redressing in the roll shop. If a major defect is present in a forged roll, e.g. due to a mill incident, catastrophic roll failure may occur in a violent, explosive manner. Improvement of the value-in-use of a work roll implies a superior wear resistance, a superior damage resistance, and elimination of the safety risks associated with explosive roll failures. In order to deal with this in a concerted R&D approach, a consortium of two roll users in the steel industry, a leading roll manufacturer, a high-tech supplier of roll damage detection equipment, and specialised research institutes have joined forces. Cold rolling trials have been performed, using pilot mills as well as industrial mills, with both novel forged HSS work rolls and conventional forged 3–5%Cr steel work rolls. Separate trials have been designed to focus on either the aspect of roughness evolution or damage resistance. Complementary data from various laboratory tests and industrial mill and roll shop data have been collected. Models have been developed for damage evolution in a roll, and for roughness evolution of the roll surface. In addition, novel non-destructive detection systems and sensors have been designed and tested. This paper provides a concise overview of the results achieved.
This paper describes implementation and initial evaluation of
variable friction displays. We first analyse a device that comprises a stator of an ultrasonic motor supplied by only
one channel. In this way, the stator does not induce any rotative movement but
creates a slippery feeling on the stator's surface. Considering the range of frequency and amplitude needed to obtain this phenomenon, we
interpret it as the squeeze film effect, which may be the dominant factor causing an impression of lubrication. This effect is thus able to decrease
the friction coefficient between the fingertip and the stator as a function of the vibration amplitude. Moreover, if we add a position sensor, we can create a textured surface by generating alternatively sliding and braking sensations by tuning the vibration amplitude of the wave.
Then, based on the principle of the first device, another device is
proposed in order to enable a free exploration of the surface, according to ergonomic requirements.
Previous research has shown that a preoperative assessment clinic enhances hospital cost-efficiency. However, the differences in organization of the patient flow have not been analysed. In this descriptive study, we evaluated the consequences of the organization of the patient flow of a preoperative assessment clinic on its performance, by analysing two Dutch university hospitals, which are organized essentially differently.
In the final analysis, the study included 880 patients who visited either academic centre. The performance of the two preoperative assessment clinics was evaluated by measuring patient flow time, various procedure times and the total waiting time. Patients’ age, ASA physical status and any preoperative tests requested by the physician were also recorded.
There was a significant difference in patient flow time between the two preoperative assessment clinics. More time was needed for the preoperative assessment when patients’ ASA class was higher. The patient flow time was longer when electrocardiogram and venepuncture were performed at the general outpatient laboratory than when they were performed at the preoperative assessment clinic due to longer waiting times. More tests were requested when they were performed at the preoperative assessment clinic.
This study shows that the organization of patient flow is an important aspect of the logistic processes of the preoperative assessment clinic. It might influence patient flow times as well as the number of preoperative tests requested. Together with other aspects of logistic performance, patient satisfaction and quality of medical assessment, patient flow logistics can be used to assess the quality of a preoperative assessment clinic.
High power RF device performance
decreases as operation temperature increases (e.g. decreasing electron
mobility affects cut-off frequencies and degrades device reliability).
Therefore determination of device temperature is a key issue for device
topology optimisation. In this work the temperature variation of AlGaN/GaN
high-electron-mobility transistors grown either on silicon or sapphire
substrate under bias operation was measured by micro Raman scattering
spectroscopy. Temperature measurements up to power dissipation of 16 W for
4 mm development devices were carried out and a peak temperature of 650 K was
determined. The difference of thermal resistance for similar devices grown
on the two different substrates was assessed. The thermal resistances of
different device topologies were compared to optimise the component design.
The high power RF device performance decreases as the operation
temperature increases (e.g. fall of electron mobility impacting
the cut-off frequencies and degradation of device reliability).
Therefore the determination of device temperature is a key issue
for device topology optimisation. In this work the temperature
variation of AlGaN/GaN high-electron-mobility transistors grown
either on silicon or sapphire substrates under bias operation was
measured by micro Raman scattering spectroscopy. The differences
in thermal resistance for similar devices grown on the two
different substrates were assessed. The thermal resistances of
different device topologies were compared in order to optimise
the component design. The temperature measurement across the gate
and along the component fingers were made to quantify the thermal
gradient of the device. Temperature measurement up to a power
dissipation of 16 W for a 4 mm development device was carried out
and the peak temperature of 650 K was determined.
D. Field, Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark and Observatoire de Paris-Meudon,
J. L. Lemaire, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France; Université de Cergy-Pontoise, F-95806 Cergy Cedex, France,
J. P. Maillard, Institut d'Astrophysique, 98bis, Boulevard Arago, F-75014 Paris, France,
S. Leach, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France,
G. Pineau des Forêts, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France,
E. Falgarone, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris Cedex 05, France,
F. P. Pijpers, Theoretical Astrophysics Centre, University of Aarhus, DK-8000 Aarhus C, Denmark,
M. Gerin, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris Cedex 05, France,
F. Rostas, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France,
D. Rouan, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France,
L. Vannier, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France
High spatial and spectral resolution observations are reported of H2 infrared emission from the reflection nebulæ NGC2023 and NGC7023. The local molecular gas is strongly perturbed by the presence of the massive stars which power these nebulae. Data yield information on the small-scale structure, the temperature and density and the dynamics of the excited gas. Excited material is found to be hot (400-500K), dense (105-106 cm−3) and clumped containing substantial flows and velocity fields.
The two reflection nebulæ NGC2023 and NGC7023 are prototypes of regions in which recently formed massive stars are interacting strongly with their parent gas. The outcome of these interactions is important in understanding the cycle of star formation in which massive stars are created and, by perturbing their surroundings, influence the nature of the gas in which future stars may form. The goal of our work is to examine in detail the perturbed gas around massive young stars. Some of the observations of infrared (IR) emission of molecular hydrogen in NGC2023 and NGC7023, performed in recent years in our group, are described below.
Nebulosity in NGC2023 and NGC7023 is excited by B-stars of temperatures respectively 22,000K and 20,400K. The distance between the star and the illuminated surrounding gas is ∼ 0.1 pc in both nebulæ. NGC2023 shows a strong IR excess with emission from small dust particles plus extended red emission, and has an associated molecular cloud with OH, HCHO, HCN, CO, CH, CH+ and other detections (see Field et al. 1994).
Les auteurs se sont intéressés à la réaction nucléaire 32S(n, p) 32P qui a lieu
entre autres dans les phanères de l'homme (cheveux et poils) lors d'accident de
criticité ou de surexposition aux neutrons d'énergie supérieure à 2,5 MeV. La
présence de 32P dans les cheveux ou les poils est un signe indiscutable d'une
exposition aux neutrons rapides. L'activité du 32P décelée est directement proportionnelle
à la fluence neutronique. Elle permet une estimation précise de la
dose absorbée dès lors que l'on connaît la nature du spectre incident. La
connaissance du rapport neutron/gamma autorise même l'estimation de la dose
totale absorbée (neutron + gamma).
Les petites quantités de phanères nécessaires aux mesures (quelques dizaines
de mg) permettent sur un individu de pilosité moyenne de faire des prélèvements
en différents points du corps. On en déduit alors le vecteur directeur de
la fluence incidente et l'hétérogénéité de l'exposition. Cette méthode est opérationnelle.
Elle n'exige pas de radiochimie trop ardue. Elle apporte des données
dosimétriques très fiables aux cliniciens en moins de vingt quatre heures. Le
seuil de détection est de quelques dizaines de centigray.
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