269 research outputs found
Translating the Gospels - A Discussion Between Dr. E. V. Rieu and the Rev. J.B. Phillips
Translating the Gospels - A Discussion Between Dr. E. V. Rieu and the Rev. J.B. Phillip
Diversification and hybridization in firm knowledge bases in nanotechnologies
The paper investigates the linkages between the characteristics of
technologies and the structure of a firms' knowledge base. Nanotechnologies
have been defined as converging technologies that operate at the nanoscale, and
which require integration to fulfill their economic promises. Based on a
worldwide database of nanofirms, the paper analyses the degree of convergence
and the convergence mechanisms within firms. It argues that the degree of
convergence in a firm's nano-knowledge base is relatively independent from the
size of the firm's nano-knowledge base. However, while firms with small
nano-knowledge bases tend to exploit convergence in each of their
patents/publications, firms with large nano-knowledge bases tend to separate
their nano-R&D activities in the different established fields and achieve
diversity through the juxtaposition of the output of these independent
activitie
Are Laparoscopic Staplers Effective for Ligation of Large Intraabdominal Arteries?
AbstractObjectives. To evaluate ligation of aortoiliac arteries with laparoscopic staplers in order to develop specifically designed staplers.Methods. Cadaveric study. Seven human cadaver aortas were stapled using EndoGIA60Âź staplers. Efficiency was evaluated macroscopically and on a hydrodynamic bench.Clinical study. Twelve patients had ligation of 14 large abdominal arteries (aorta: nine, iliac artery: four, hepatic artery: one) using a laparoscopic stapler. Stapling efficiency was judged on peroperative clinical and postoperative CT scan criteria.Results. Cadaveric study. Stapling was performed perfectly on four moderately calcified aortas, without leakage with a pulsatile pressure of >250 mmHg. For three aortas with severe calcification, stapling was not efficient and major leakage occurred.Clinical study. Stapling appeared clinically efficient on all arteries but one aorta: this severely calcified aorta was ligated conventionally. The staplers are not easy to use due to their shape and their lack of articulation. After a mean follow-up of 31.3 months, all the other stapled arteries were effectively ligated.Conclusion. The commercially available staplers can be used securely on moderately calcified arteries but stapling of severely calcified arteries should be avoided. These devices should be redesigned to facilitate their use in vascular surgery
Distribution and kinematics of the HCN(3-2) emission down to the innermost region in the envelope of the O-rich star W Hya
We report high angular resolution observations of the HCN (3-2) line emission
in the circumstellar envelope of the O-rich star W Hya with the Submillimeter
Array. The proximity of this star allows us to image its molecular envelope
with a spatial resolution of just ~40 AU, corresponding to about 10 times the
stellar diameter. We resolve the HCN (3-2) emission and find that it is
centrally peaked and has a roughly spherically symmetrical distribution. This
shows that HCN is formed in the innermost region of the envelope (within ~10
stellar radii), which is consistent with predictions from pulsation-driven
shock chemistry models, and rules out the scenario in which HCN forms through
photochemical reactions in the outer envelope. Our model suggests that the
envelope decreases steeply in temperature and increases smoothly in velocity
with radius, inconsistent with the standard model for mass-loss driven by
radiative pressure on dust grains. We detect a velocity gradient of ~5 km/s in
the NW--SE direction over the central 40 AU. This velocity gradient is
reminescent of that seen in OH maser lines, and could be caused by the rotation
of the envelope or by a weak bipolar outflow.Comment: accepted for publication in ApJ
Representation de connaissances dynamiques dans SHERPA
On decrit un modele de representation des connaissances developpe dans le cadre du projet Sherpa. L'objectif du projet est de definir, mettre en oeuvre et experimenter un systeme de representation de connaissances dynamiques base sur un modele a objets. Sherpa est un projet commun Imag et Inria. Les racines du modele se trouvent en intelligence artificielle, dans le domaine des bases de donnees orientees-objet et en CAO. Le modele presente ici integre en effet des concepts issus des langages de frames, des langages orientes-objets et repond a certains besoins d'applications qui doivent gerer des objets evolutifs. On presente les concepts de base du modele, puis la semantique et la mise en oeuvre de l'heritage. On decrit ensuite la notion de relation semantique entre objets. On evoque enfin la gestion d'objets evolutifs
Herschel/HIFI deepens the circumstellar NH3 enigma
Circumstellar envelopes (CSEs) of a variety of evolved stars have been found
to contain ammonia (NH3) in amounts that exceed predictions from conventional
chemical models by many orders of magnitude. The observations reported here
were performed in order to better constrain the NH3 abundance in the CSEs of
four, quite diverse, oxygen-rich stars using the NH3 ortho J_K = 1_0 - 0_0
ground-state line. We used the Heterodyne Instrument for the Far Infrared
aboard Herschel to observe the NH3 J_K = 1_0 - 0_0 transition near 572.5 GHz,
simultaneously with the ortho-H2O J_Ka,Kc = 1_1,0 -1_0,1 transition, toward VY
CMa, OH 26.5+0.6, IRC+10420, and IK Tau. We conducted non-LTE radiative
transfer modeling with the goal to derive the NH3 abundance in these objects'
CSEs. For the latter two stars, Very Large Array imaging of NH3
radio-wavelength inversion lines were used to provide further constraints,
particularly on the spatial extent of the NH3-emitting regions. Results. We
find remarkably strong NH3 emission in all of our objects with the NH3 line
intensities rivaling those obtained for the ground state H2O line. The NH3
abundances relative to H2 are very high and range from 2 x 10-7 to 3 x 10-6 for
the objects we have studied. Our observations confirm and even deepen the
circumstellar NH3 enigma. While our radiative transfer modeling does not yield
satisfactory fits to the observed line profiles, it leads to abundance
estimates that confirm the very high values found in earlier studies. New ways
to tackle this mystery will include further Herschel observations of more NH3
lines and imaging with the Expanded Very Large Array.Comment: 4+2 page
Living biointerfaces based on non-pathogenic bacteria to direct cell differentiation
Genetically modified Lactococcus lactis, non-pathogenic bacteria expressing the FNIII7-10 fibronectin fragment as a protein membrane have been used to create a living biointerface between synthetic materials and mammalian cells. This FNIII7-10 fragment comprises the RGD and PHSRN sequences of fibronectin to bind α5ÎČ1 integrins and triggers signalling for cell adhesion, spreading and differentiation. We used L. lactis strain to colonize material surfaces and produce stable biofilms presenting the FNIII7-10 fragment readily available to cells. Biofilm density is easily tunable and remains stable for several days. Murine C2C12 myoblasts seeded over mature biofilms undergo bipolar alignment and form differentiated myotubes, a process triggered by the FNIII7-10 fragment. This biointerface based on living bacteria can be further modified to express any desired biochemical signal, establishing a new paradigm in biomaterial surface functionalisation for biomedical applications
Identification of superior reference genes for data normalisation of expression studies via quantitative PCR in hybrid roses (Rosa hybrida)
<p>Abstract</p> <p>Background</p> <p>Gene expression studies are a prerequisite for understanding the biological function of genes. Because of its high sensitivity and easy use, quantitative PCR (qPCR) has become the gold standard for gene expression quantification. To normalise qPCR measurements between samples, the most prominent technique is the use of stably expressed endogenous control genes, the so called reference genes. However, recent studies show there is no universal reference gene for all biological questions. Roses are important ornamental plants for which there has been no evaluation of useful reference genes for gene expression studies.</p> <p>Results</p> <p>We used three different algorithms (BestKeeper, geNorm and NormFinder) to validate the expression stability of nine candidate reference genes in different rose tissues from three different genotypes of <it>Rosa hybrida </it>and in leaves treated with various stress factors. The candidate genes comprised the classical "housekeeping genes" (<it>Actin, EF-1α, GAPDH</it>, <it>Tubulin </it>and <it>Ubiquitin</it>), and genes showing stable expression in studies in <it>Arabidopsis </it>(<it>PP2A, SAND, TIP </it>and <it>UBC</it>). The programs identified no single gene that showed stable expression under all of the conditions tested, and the individual rankings of the genes differed between the algorithms. Nevertheless the new candidate genes, specifically, <it>PP2A </it>and <it>UBC</it>, were ranked higher as compared to the other traditional reference genes. In general, <it>Tubulin </it>showed the most variable expression and should be avoided as a reference gene.</p> <p>Conclusions</p> <p>Reference genes evaluated as suitable in experiments with <it>Arabidopsis thaliana </it>were stably expressed in roses under various experimental conditions. In most cases, these genes outperformed conventional reference genes, such as <it>EF1-α </it>and <it>Tubulin</it>. We identified <it>PP2A</it>, <it>SAND </it>and <it>UBC </it>as suitable reference genes, which in different combinations may be used for normalisation in expression analyses via qPCR for different rose tissues and stress treatments. However, the vast genetic variation found within the genus <it>Rosa</it>, including differences in ploidy levels, might also influence expression stability of reference genes, so that future research should also consider different genotypes and ploidy levels.</p
Stabilization of tilt order by chain flexibility in Langmuir monolayers
Langmuir monolayers are modeled as systems of short chains, which are
confined to a planar surface at one end, but free to move within the plane. The
phase behavior is calculated in a mean field approximation, which combines the
self consistent field method with elements of classical density functional
theory. It is shown that phases with tilt order are unstable in systems of
stiff chains, but can be stabilized by chain conformational entropy in systems
of sufficiently flexible chains. The chain entropy is also responsible for the
appearance of an additional untilted phase, the liquid expanded phase. The
region of stability of the different phases is discussed, and their microscopic
structure is analyzed in some detail.Comment: to appear in Phys. Rev.
- âŠ