Quantitative stock-scion relationships in vine Preliminary investigations by the analysis of reciprocal graftings

The behaviour variations of a scion in association with düferent rootstocks are well known, particularly in so far as the expression of vigour is concerned. This simple effect is only an element of one of the possible break-down of the rootstockscion combination's quantitative characteristics.We analyse experiments of complete reciprocal grafting by use of two biometric models, one breaking down the variation for the "functions" (rootstock, scion and interaction), the other breaking down the variation for "genetic effects". Initial results allow us:1 - to test the interest of these two models and the parameters we propose,2 - to compute the quantitative importance of these parameters at differentgrowth stages.Relations quantitatives entre porte-greffe et greffon chez la vigne Première approche par l'analyse des greffages réciproquesChez la vigne, on observe que le comportement d'un même greffon peut varier lorsqu'on l'associe à différents porte-greffes; ceci a été sbuvent noté, particulièrement en ce qui concerne l'expression de la vigueur. Cet effet simple n'est en fait qu'un des éléments de la décomposition que l'on peut faire à partir de toute caractéristique ou performance quantitative de la combinaison du greffon et du porte-greffe.Par analogie avec l'étude des effets principaux et de leur interaction dans les associationsbinaires, l'analyse de greffages réciproques pêut être effectuée par le modèle biométrique suivant:Yij= m + pi+ gj + kijoù pi et gj sont respectivement ce que nous appelons les «fonctions» porte-greffe et greffon, et kij leur interaction. Une autre décomposition possible où apparaissent des «effets génétiques» est la suivante:Yij = m + ci + cj + sij + qij ci et cj étant les «Aptitudes Générales à l'Association» des génotypes i et j, sij leur «Aptitude Spécifique à l'Association» et qij l'effet réciproque de ces deux génotypes. Des expériences préliminaires basées sur un système de greffages réciproques complet de quatre génotypes, dont nous avons mesuré la croissance au cours de trois cycles de végétation, chacun de 120 jours, nous ont permis:1. de tester l'intérêt de ces deux modèles biométriques et celui des paramètres que nous proposons.2. de calculer l'ordre de grandeur de ces paramètres à différents stades de la croissance

Projectile fragmentation reactions and production of nuclei near the neutron drip-line

The reaction mechanism of projectile fragmentation at intermediate energies has been investigated observing the target dependence of the production cross sections of very neutron-rich nuclei. Measurement of longitudinal momentum distributions of projectile-like fragments within a wide range of fragment mass and its charge was performed using a hundred-MeV/n $^{40}$Ar beam incident on Be and Ta targets. By measurement of fragment momentum distribution, a parabolic mass dependence of momentum peak shift was observed in the results of both targets, and a phenomenon of light-fragment acceleration was found only in the Be-target data. The analysis of production cross sections revealed an obvious enhancement of the target dependence except target size effect when the neutron excess is increased. This result implies the breakdown of factorization (BOF) of production cross sections for very neutron-rich nuclei near the drip line.Comment: 16 pages, 18 figures, submitted to Phys. Rev.

Extracting non-linear integrate-and-fire models from experimental data using dynamic I–V curves

The dynamic I–V curve method was recently introduced for the efficient experimental generation of reduced neuron models. The method extracts the response properties of a neuron while it is subject to a naturalistic stimulus that mimics in vivo-like fluctuating synaptic drive. The resulting history-dependent, transmembrane current is then projected onto a one-dimensional current–voltage relation that provides the basis for a tractable non-linear integrate-and-fire model. An attractive feature of the method is that it can be used in spike-triggered mode to quantify the distinct patterns of post-spike refractoriness seen in different classes of cortical neuron. The method is first illustrated using a conductance-based model and is then applied experimentally to generate reduced models of cortical layer-5 pyramidal cells and interneurons, in injected-current and injected- conductance protocols. The resulting low-dimensional neuron models—of the refractory exponential integrate-and-fire type—provide highly accurate predictions for spike-times. The method therefore provides a useful tool for the construction of tractable models and rapid experimental classification of cortical neurons

Limitation of energy deposition in classical N body dynamics

Energy transfers in collisions between classical clusters are studied with Classical N Body Dynamics calculations for different entrance channels. It is shown that the energy per particle transferred to thermalised classical clusters does not exceed the energy of the least bound particle in the cluster in its ``ground state''. This limitation is observed during the whole time of the collision, except for the heaviest system.Comment: 13 pages, 15 figures, 1 tabl

Ruthenacycles and Iridacycles as Catalysts for Asymmetric Transfer Hydrogenation and Racemisation

Ruthenacycles, which are easily prepared in a single step by reaction between enantiopure aromatic amines and [Ru(arene)Cl2]2 in the presence of NaOH and KPF6, are very good asymmetric transfer hydrogenation catalysts. A range of aromatic ketones were reduced using isopropanol in good yields with ee’s up to 98%. Iridacycles, which are prepared in similar fashion from [IrCp*Cl2]2 are excellent catalysts for the racemisation of secondary alcohols and chlorohydrins at room temperature. This allowed the development of a new dynamic kinetic resolution of chlorohydrins to the enantiopure epoxides in up to 90% yield and 98% enantiomeric excess (ee) using a mutant of the enzyme Haloalcohol dehalogenase C and an iridacycle as racemisation catalyst.

A highly stable atomic vector magnetometer based on free spin precession

We present a magnetometer based on optically pumped Cs atoms that measures the magnitude and direction of a 1 $\mu$T magnetic field. Multiple circularly polarized laser beams were used to probe the free spin precession of the Cs atoms. The design was optimized for long-time stability and achieves a scalar resolution better than 300 fT for integration times ranging from 80 ms to 1000 s. The best scalar resolution of less than 80 fT was reached with integration times of 1.6 to 6 s. We were able to measure the magnetic field direction with a resolution better than 10 $\mu$rad for integration times from 10 s up to 2000 s

On the reliability of negative heat capacity measurements

A global protocol for the thermostatistical analysis of hot nuclear sources is discussed. Within our method of minimization of variances we show that the abnormal kinetic energy fluctuation signal recently reported in different experimental data (M.D'Agostino et al.-Phys. Lett. B 473 (2000) 219, N. Le Neindre et al.- contr. to the XXXVIII Bormio Winter Meeting on Nucl. Phys. (2001) 404) is a genuine signal of a first order phase transition in a finite system.Comment: 15 Postscript figures, submitted to NUCL. Phys. A on 24-apr-200

An Improved Neutron Electric Dipole Moment Experiment

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase.Comment: Flavor Physics & CP Violation Conference, Taipei, 200