816 research outputs found
The Ranking of Economists and Management Scientists in Europe
Cet article présente une analyse statistique de la position des économistes français et des spécialistes français des sciences de gestion parmi les chercheurs européens de haut rang. La preuve empirique révÚle que la France ne développe pas fortement ses ressources humaines sur la scÚne internationale. La position de la France en Europe, repérée par les citations (pour les économistes) et les nominations par les pairs (pour les spécialistes des sciences de gestion) des chercheurs de haut rang et normalisée par la taille de la population, est seulement au neuviÚme rang en ce qui concerne les sciences économiques et au huitiÚme rang pour les sciences de gestion. Cela laisse penser que la politique scientifique a encore beaucoup à faire pour améliorer la situation.This note provides a statistical analysis of the position of French economists and French management scientists among the leading European scholars. The evidence shows that France does not strongly develop its human resources in the international setting. Frances position in Europe based on citations (for economists) and peer nominations (for management scientists) of the leading scholars normalized by the size of the population is only rank 9 with respect to economics, and rank 8 with respect to management science. This suggests that there is considerable scope for science policy to improve this situatio
Experimental assessment of the speed of light perturbation in free-fall absolute gravimeters
Precision absolute gravity measurements are growing in importance, especially
in the context of the new definition of the kilogram. For the case of free-fall
absolute gravimeters with a Michelson-type interferometer tracking the position
of a free falling body, one of the effects that needs to be taken into account
is the speed of light perturbation due to the finite speed of propagation of
light. This effect has been extensively discussed in the past, and there is at
present a disagreement between different studies. In this work, we present the
analysis of new data and confirm the result expected from the theoretical
analysis applied nowadays in free-fall gravimeters. We also review the standard
derivations of this effect (by using phase shift or Doppler effect arguments)
and show their equivalence
Photochemical Conjugation and One-Pot Radiolabelling of Antibodies for Immuno-PET
Monoclonal antibodies (mAbs), immunoglobulin fragments, and other proteins are important scaffolds in the development of radiopharmaceuticals for diagnostic immunoâpositron emission tomography (immunoâPET) and targeted radioimmunotherapy (RIT). Conventional methods for radiolabelling proteins with metal ions such as 68Ga, 64Cu, 89Zr, and 90Y require multiâstep procedures involving preâpurification, functionalisation with a chelate, and subsequent radiolabelling. Standard coupling chemistries are timeâconsuming, difficult to automate, and involve synthesis, isolation, and storage of an intermediate, new molecular entity (the conjugated mAb) whose biochemical properties can differ from those of the parent protein. To circumvent these issues, we developed a photoradiochemical approach that uses fast, chemoselective, lightâinduced protein modification under mild conditions with novel metalâionâbinding chelates derivatised with aryl azide (ArN3) groups. Experiments show that oneâpot photochemical conjugation and radiolabelling of formulated mAbs can be achieved in <20â
min
Electric field dependence of thermal conductivity of a granular superconductor: Giant field-induced effects predicted
The temperature and electric field dependence of electronic contribution to
the thermal conductivity (TC) of a granular superconductor is considered within
a 3D model of inductive Josephson junction arrays. In addition to a
low-temperature maximum of zero-field TC K(T,0) (controlled by mutual
inductance L_0 and normal state resistivity R_n), the model predicts two major
effects in applied electric field: (i) decrease of the linear TC, and (ii)
giant enhancement of the nonlinear (i.e., grad T-dependent) TC with
[K(T,E)-K(T,0)]/K(T,0) reaching 500% for parallel electric fields E=E_T
(E_T=S_0|grad T| is an "intrinsic" thermoelectric field). A possiblity of
experimental observation of the predicted effects in granular superconductors
is discussed.Comment: 5 LaTeX pages (jetpl.sty included), 2 EPS figures. To be published in
JETP Letter
Follow-up of Bernese Mountain dogs and other dogs with serologically diagnosed Borrelia burgdorferi infection: what happens to seropositive animals?
BACKGROUND: Data on the long-term outcome of B. burgdorferi infections in adult dogs are sparse. The aim of the present study was to investigate whether Bernese Mountain dogs with serological evidence of natural B. burgdorferi infection more often develop signs such as lameness, azotemia or proteinuria during a follow-up period of 2.5 to 3.0 years. Seropositive Bernese Mountain dogs were compared to seronegative Bernese Mountain dogs and to seropositive and seronegative control dogs of other breeds. Dogs included in a previous study on the prevalence of antibodies against B. burgdorferi in Bernese Mountain dogs were re-evaluated. Antibodies against B. burgdorferi were determined using an ELISA with a whole-cell sonicate as antigen and results were confirmed using a Western blot assay. RESULTS: Fifty-three Bernese Mountain dogs and 30 control dogs were re-evaluated. Re-evaluation was performed between 2.5 and 3.0 years (median 2.7 years) after the first assessment.The age of the dogs at the second evaluation ranged from 3 to 11 years (median 6 years). There were no significant differences with regard to poor general condition or lameness between the first and the second evaluation. At the first evaluation 22 (42%) of the Bernese Mountain dogs and 11 (37%) of the control dogs were considered positive for antibodies against B. burgdorferi. At the second evaluation 25 (47%) of the Bernese Mountain dogs and 12 (40%) of the control dogs were considered positive; 69% of the dogs showed the same serological result at both examinations and 31% were seroconverted or seroreverted. During the first examination, azotemia was diagnosed in 6 Bernese Mountain dogs and during the second examination in 11 Bernese Mountain dogs. No control dogs had azotemia in this study. In seropositive dogs there was no increase in lameness or signs of renal disease over time. CONCLUSION: It may be concluded that antibodies against B. burgdorferi determined by whole cell ELISA and confirmed by Western blot were neither associated with the development of lameness nor with signs of renal disease like azotemia or proteinuria in dogs observed over a period of 2.5 to 3.0 years
Ultrasound-guided thoracic paravertebral puncture and placement of catheters in human cadavers: where do catheters go?â
Background Paravertebral regional anaesthesia is used to treat pain after several surgical procedures. This study aimed to improve on our first published ultrasound-guided approach to the paravertebral space (PVS) and to investigate a possible discrepancy between the needle, catheter, and contrast dye position. Methods In 10 cadavers, we conducted 26 ultrasound-guided paravertebral approaches combined with loss of resistance (LOR) and after an interim analysis performed 36 novel, pure ultrasound-guided (PUSG) paravertebral approaches. Needle-tip position was controlled by a first computed tomography (CT) scan. After placement of the catheters, the tips were assessed by a second CT and the spread of injected contrast dye was assessed by further CT scans. The part of the PVS near the intervertebral foramen was defined as the primary target to reach. Results The first CT scans assessing 62 needle tips revealed that: 13 (50%) of LOR and 34 (94%) of PUSG approaches were at the target; and two (8%) LOR and no PUSG approaches were outside the PVS. With the second CT scans 60 catheter-tip positions were analysed: three (12%) of LOR and five (14%) of PUSG approaches were at the target, three (12%) of LOR and two (6%) of PUSG approaches were outside the PVS. No catheters were detected in the epidural space. In two cases, insertion of the catheter was not possible. In cases with major epidural contrast, the widest contrast dye spread was 7.7 (3.5) [mean (sd)] vertebral segments. Conclusions Our new PUSG technique has a high success rate for paravertebral needle placement. Although needles were correctly positioned, catheters were usually found distant from the needle-tip positio
Ultrasound-guided percutaneous tracheal puncture: a computer-tomographic controlled study in cadavers
Background Ultrasound-guided techniques are increasingly used in anaesthetic practice to identify tissues beneath the skin and to increase the accuracy of placement of needles close to targeted structures. To examine ultrasound's usefulness for dilatational tracheostomy, we performed ultrasound-guided tracheal punctures in human cadavers followed by computer-tomographic (CT) control. Methods The trachea of nine cadavers was punctured using an in-plane approach with a longitudinal ultrasound visualization of the trachea. As soon as a loss of resistance was felt, or air/fluid could be aspirated into the attached syringe, the syringe was disconnected and the ultrasound transducer set aside. Thereafter, a cricothyroidotomy guidewire was inserted through the needle into the trachea. The needle was then removed, leaving the wire in place and a control CT imaging of the neck and the chest was performed. Primary outcome was successful wire insertion into the trachea. Results Tracheal puncture and wire insertion was successful in eight of nine cadavers at the first attempt and in one at the second attempt (total of 10 puncture attempts, nine successful). In eight of nine successfully inserted wires, the wire was placed on the defined midline. Conclusions Ultrasound guidance can facilitate successful tracheal puncture. However, combining an in-plane approach with a longitudinal ultrasound visualization of the trachea neither guarantees an exact midline puncture nor allows detection of a misplaced guidewir
Lumbar epidural fentanyl: segmental spread and effect on temporal summation and muscle pain
Background. Despite extensive use, different aspects of the pharmacological action of epidural fentanyl have not been clarified. We applied a multiâmodal sensory test procedure to investigate the effect of epidural fentanyl on segmental spread, temporal summation (as a measure for shortâlasting central hyperexcitability) and muscle pain. Methods. Thirty patients received either placebo, 50 or 100 ”g single dose of fentanyl epidurally (L2-3), in a randomized, doubleâblind fashion. Heat pain tolerance thresholds at eight dermatomes from S1 to fifth cranial nerve (assessment of segmental spread), pain threshold to transcutaneous repeated electrical stimulation of the sural nerve (assessment of temporal summation) and pain intensity after injection of hypertonic saline into the tibialis anterior muscle (assessment of muscle pain) were recorded. Results. Fentanyl 100 ”g, but not 50 ”g, produced analgesia to heat stimulation only at L2. Surprisingly, no effect at S1 was detected. Both fentanyl doses significantly increased temporal summation threshold and decreased muscle pain intensity. Conclusions. The findings suggest that a single lumbar epidural dose of fentanyl should be injected at the spinal interspace corresponding to the dermatomal site of pain. Increased effect on L2 compared with S1 suggests that drug effect on spinal nerve roots and binding to opioid receptors on the dorsal root ganglia may be more important than traditionally believed for the segmental effect of epidurally injected fentanyl. Epidural fentanyl increases temporal summation threshold and could therefore contribute to prevention and treatment of central hypersensitivity states. I.M. injection of hypertonic saline is a sensitive technique for detecting the analgesic action of epidural opioids. Br J Anaesth 2003; 90: 467-7
Competing adaptations maintain nonadaptive variation in a wild cricket population.
How emerging adaptive variants interact is an important factor in the evolution of wild populations, but the opportunity to empirically study this interaction is rare. We recently documented the emergence of an adaptive phenotype "curly-wing" in Hawaiian populations of field crickets (Teleogryllus oceanicus). Curly-wing inhibits males' ability to sing, protecting them from eavesdropping parasitoid flies (Ormia ochracea). Surprisingly, curly-wing co-occurs with similarly protective silent "flatwing" phenotypes in multiple populations, in which neither phenotype has spread to fixation. These two phenotypes are frequently coexpressed, but since either sufficiently reduces song amplitude to evade the fly, their coexpression confers no additional fitness benefit. Numerous "off-target" phenotypic changes are known to accompany flatwing, and we find that curly-wing, too, negatively impacts male courtship ability and affects mass and survival of females under lab conditions. We show through crosses and genomic and mRNA sequencing that curly-wing expression is associated with variation on a single autosome. In parallel analyses of flatwing, our results reinforce previous findings of X-linked single-locus inheritance. By combining insights into the genetic architecture of these alternative phenotypes with simulations and field observations, we show that the co-occurrence of these two adaptations impedes either from fixing, despite extreme fitness benefits, due to fitness epistasis. This co-occurrence of similar adaptive forms in the same populations might be more common than is generally considered and could be an important force inhibiting adaptive evolution in wild populations of sexually reproducing organisms
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