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An Italian greyhound was presented three times during a two-year period for dental prophylaxis due to periodontal disease. Clinical examination revealed lesions on several teeth. Radiographs revealed extensive resorptive root lesions. On histological examination, the presence of odontoclasts and signs of boney remodeling of the roots confirmed the resorptive nature of the lesions. Given the extent of the lesions, and poor prognosis with conservative treatment alone, teeth affected by the most severe resorption were extracted at each visit using a flap technique combined with alveolar vestibular osteotomy. Dental resorptive lesions are rarely detected in the dog but may be more frequent than previously thought. The routine use of dental radiographs can be used to reveal these lesions in the dog.

This paper presents the effects of charge injection error on switched-current Divider Circuits. Algorithmic structures of current dividers are presented and the charge injection error is evaluated at each iteration of the Algorithm. Therefore, the current final value is estimated and compensated methods to cancel this error are proposed for each structures.

We consider the Schr?dinger operator H = (i? + A)2 in the space L2(2) with a magnetic potential A(x) = a()(?x2, x1) |x|?2, where a is an arbitrary function on the unit circle. Our goal is to study spectral properties of the corresponding scattering matrix S(?), ? > 0. We obtain its stationary representation and show that its singular part (up to compact terms) is a pseudodifferential operator of zero order whose symbol is an explicit function of a. We deduce from this result that the essential spectrum of S(?) does not depend on ? and consists of two complex conjugated and perhaps overlapping closed intervals of the unit circle. Finally, we calculate the diagonal singularity of the scattering amplitude (kernel of S(?) considered as an integral operator). In particular, we show that for all these properties only the behaviour of a potential at infinity is essential. The preceding papers on this subject treated the case a() = const and used the separation of variables in the Schr?dinger equation in the polar coordinates. This technique does not, of course, work for arbitrary a. From an analytical point of view, our paper relies on some modern tools of scattering theory and well-known properties of pseudodifferential operators.

A Lhassa Apso is presented in emergency after having been injured by another dog. It was suffering from a mandibular fracture. The clinical exam revealed generalized and excessive mobility of the whole dentition. Radiographs showed generalized jaw bone demineralisation. A blood sample was analysed and revealed chronic renal disease. We came to the conclusion that this dog was suffering from secondary renal hyperparathyroidism. The hypocalcified bone was so thin that a slight trauma induced the mandibular fracture.

The dwarf rabbit often suffers from dental malocclusion, particularly on the level of the incisors. A too short maxillary jawbone in these brachycephalic animals is the cause. The treatment of first intention consists in reducing the overgrowth using a diamond bur, but like the problem repeats quickly, an alternative consists in extracting the 6 incisors.

The preferential dissociation channels of singly and doubly charged antimony clusters have been determined from the unimolecular dissociation of energy rich cluster ions, using an ion stopping technique. It is found that singly charged Sb+n clusters with 5≤n≤80 dissociate by loss of neutral molecules. Neutral dimer loss is observed for n=5, 6, 7 whereas for n≥8, Sb+n loses Sb4. The fragmentation of doubly charged Sb++n has been investigated above the critical size n++c=24 from which doubly charged clusters are detectable in mass spectra. On the time scale of the experiment, which is 1 μs≤t≤100 μs with respect to photoionization, the delayed Coulombic fission into two singly charged clusters competes with the evaporation of Sb4. It is shown that for the smaller Sb++n clusters with 26≤n≤36 the fission to two singly charged clusters is of relatively asymmetrical character, leading to the detachment of five and seven atom cationic fragments. In larger clusters n≥40 the fission is of more symmetrical character...

Lithium oxide clusters Li2n+pOn+ are generated by combining reactive nucleation in a gas aggregation source and photoionization. Unimolecular dissociation of mass selected cluster ions provides evidence that the excess of metal atoms evaporates first leading to the most stable species Li+(Li2O)n, which then evaporate Li2O molecules. The evaporation rate behavior as a function of cluster size demonstrates that Li+(Li2O)n can be prepared with different temperatures. It is discussed how metal evaporation from metal‐rich oxide clusters leads to oxygen saturated clusters with a lower temperature. An estimate of the dissociation energies of Li+(Li2O)n are given for small sizes n≤10 from photoevaporation experiment.

Rare earth clusters of europium, thullium and ytterbium were generated by gas aggregation technique and probed by photoionization mass spectrometry. Their relative intensities in mass spectra have shown that their stabilities are governed by compact geometrical structures. The addition of oxygen gas in the nucleation region was used to produce the reactive nucleation. Several stages of oxidation were observed as a function of oxygen pressure up to saturation. For the maximal degree of oxidation the observed oxide ion compositions enable one to follow the valence of metal atom in its oxide as cluster size increases. This exhibits a divalent to trivalent valence change with cluster size. Moreover it emerges from the data that the divalent to trivalent transition for Tm, Yb, and Eu occurs at different size values.

Two different approaches for studying the electronic structure of clusters are presented. The physical probe uses the photoexcitation of size selected alkali-atom clusters. Giant resonances govern the absorption cross-section. It is due to the collective excitation of delocalized valence electrons. The behavior of the resonance up to large sizes, 900-atom clusters for potassium and 1500-atom clusters for lithium puts into evidence the failure of the jellium model for lithium. The chemical approach makes use of the nucleation process in the presence of oxygen. From the analysis of mass spectra of oxidized products, informations are gained on the valence of metallic atom in the cluster oxide. The method is applied to europium and thulium clusters. A comparison is done with the simple case of alkali clusters.

Alkali clusters arc considered as prototypes of metallic clusters since their electrons arc delocalized from the small sizes. The two techniques applied here I-c- photoionization and its reverse neutralization by charge exchange probe the delocalization of their valence electrons. These methods extending over other elements should produce a pertinent analyse of the binding evolution with cluster size.

A Lhassa Apso is presented in emergency after having been injured by another dog. It was suffering from a mandibular fracture. The clinical exam revealed generalized and excessive mobility of the whole dentition. Radiographs showed generalized jaw bone demineralisation. A blood sample was analysed and revealed chronic renal disease. We came to the conclusion that this dog was suffering from secondary renal hyperparathyroidism. The hypocalcified bone was so thin that a slight trauma induced the mandibular fracture.

The dwarf rabbit often suffers from dental malocclusion, particularly on the level of the incisors. A too short maxillary jawbone in these brachycephalic animals is the cause. The treatment of first intention consists in reducing the overgrowth using a diamond bur, but like the problem repeats quickly, an alternative consists in extracting the 6 incisors.

The first European Standard for the design of commercial-production greenhouses has been drafted and reaches the formal voting stage in 2000. For structural design considerations, it is based on the Eurocodes, and so for wind loading it is based on ENV 1991-2-4: 1995, although it provides additional informatio where specific data available. During the dradting exercise, one deficiency identified in available wind loading was that of pressure coefficient data for permeably-clad structures.Greenhouses, particularly flat shading structures and curved roof houses, are often clad in permeable shade or insect-proof netting in southern Europe to reduce solar radiation gain and to increase ventilation. To facilitate reliable design of such structures, pressure data were obtained from large-scale tests conduted in the Jules Verne climatic wind tunnel at CSTB, Nantes, in november 1999. This paper reports the experiments conducted on an arch structure and on a flat-roof structure, where each was clad in turn in an impermeable plastic film, a, 'insect net' of 33% open aera, and a 'shade net' of 39% open aera. The pressure coefficient data obtained with each cladding are compared for each of the two structural forms., La première norme européenne pour la conception des serres de production a été réalisée et atteindra l'étape finale du vote formel en 2000. Pour des considérations structurales de conception, elle est basée sur les Eurocodes (ainsi pour les charges de vent elle est basée sur ENV 1991-2-4 : 1995), bien qu'elle fournisse des informations supplémentaires la où des données spécifiques sont disponibles. Pendant ces travaux, une insuffisance de données sur les coefficients de pression pour les structures recouvertes de matériaux perméable a été identifiée. En Europe du sud, les serres, en particulier les ombrières plates et les tunnels, sont souvent couverts de matériaux perméable ou de filets insect-proof pour réduire la radiation solaire et pour augmenter la ventilation. Pour faciliter la conception fiable de telles structures, des données de pression ont été obtenues à partir d'essais à grandes échelle effectués dans la soufflerie climatique 'Jules Verne' du CSTB à Nantes, en novembre 1999. Cet article rapporte les expériences entreprises sur une structure tunnel et sur une structure plate, alternativement couvertes d'un film plastique imperméable, d'un 'filet insect-proof' de porosité 33%, et un "filet d'ombrage' de porosité 39%. Les données de coefficients de pression obtenues avec chaque couverture sont comparées pour chacune des deux formes structurales.

Metal cluster provides an ideal object to study a many body system. In particular it consists of many electrons which strongly interact each other. Two kinds of electrons may be distinguished i.e.: the valence electrons which become more delocalized as the cluster size increases, and the core electrons which may remain localized around each nucleus whatever the cluster size is. The correlations between the electrons, within each variety, induce collective effects revealed by the observation of giant resonances.

Shell and supershell structures have been observed for lithium clusters produced in a gas-aggregation type source, up to the size range n≃2000. Noteworthy similarities are found as compared with observations performed on Nan clusters. Thermal effects are briefly investigated.

The photoionization of antimony clusters has been studied in the energy range 20-120 eV, probing the inner-valence 4d-np transitions as well as the shape resonance 4d-∈f. When the cluster size is varied the photoionization efficiency presents a quite surprising behavior. For all clusters, except the Sb 4p group with p>1, the photoionization pattern is similar to that which is known for the bulk. On the other hand, the shape resonance collapses completely for Sb 4p

We consider the Schrodinger operator H=(i∇+A)2+V in the space L2(Rd) with long-range electrostatic V(x) and magnetic A(x) potentials. Using the scheme of smooth perturbations, we give an elementary proof of the existence and completeness of modified wave operators for the pair H0=−Δ, H. Our main goal is to study spectral properties of the corresponding scattering matrix S(λ). We obtain its stationary representation and show that its singular part (up to compact terms) is a pseudodifferential operator with an oscillating amplitude which is an explicit function of V and A. Finally, we deduce from this result that, in general, for each λ>0 the spectrum of S(λ) covers the whole unit circle.

Photofragmentation studies are described for size‐selected ionized potassium‐atom clusters, generated in a supersonic expansion and analyzed with a tandem time‐of‐flight system. In the range n=3 to 41 the relative ion intensities in photofragmentation spectra reflect the relative stabilities of the ion products. Moreover the photon‐energy dependence of the fragmentation patterns suggests that photodissociation proceeds rather via a fast sequential evaporation of neutral monomers than via a fission process. A value can be deduced for the mean binding energy per atom which is increasing with the cluster size.

Neutral potassium clusters of two different mass distributions generated either by a sonic or a conical nozzle were photoionized at several ionizing energies. By combining different nucleation conditions with several photoionization situations, variations of ion mass spectral patterns reflecting either neutral or ionic stabilities were obtained. The spectra show peaks or steps for those neutral and ionized clusters which contain 8, 20, and 40 electrons. These can be understood in terms of electronic shell structure for both neutral and ionized potassium clusters. However local irregularities appearing for the small cluster sizes reveal the influence of their geometrical structure. Moreover ionizing laser power dependencies taken at various photon energies were used to study fragmentation effects following ionization.

The unimolecular dissociation of metastable photoionized mass‐selected heterogeneous alkali clusters is investigated using a tandem time‐of‐flight spectrometer. NaK+n and Nan K+ are found to dissociate by evaporation of either a single neutral atom or a neutral dimer of the most abundant constituant. This behavior differs from the evaporation of heterogeneous neutral clusters which might always evaporate potassium in order to explain the sodium enrichment in the NaxKy neutral cluster distributions. This difference in the dissociation patterns of neutral and ionic heterogeneous clusters puts into evidence the influence of the charge in unimolecular dissociation processes.

The decomposition of metastable photoionized mass‐selected alkali clusters is investigated using a tandem time‐of‐flight spectrometer. Na+n and K+n are found to decompose mainly by the evaporation of either a single neutral atom or a neutral dimer in a time scale of about 10 μs. The predominant fragmentation channels are found to follow the adiabatic dissociation channels associated with the lowest energies accordingly to our CI calculations. In the light of our experimental and theoretical results a comparison between the different calculations of the absolute atomization energies available in the literature is presented.

Photoionization of small K n and NaK n −1 clusters with n ⩽ 34 has been achieved in a crossed laser-molecular-beam experiment. The relative ion peak intensities in mass spectra reveal fragmentation effects which are wavelength-dependent. The vertical ionization profiles in the threshold region give some insight into the electronic structure.

The avalanche degradation phenomenon model presented here takes into account both : an increase of surface recombination rate localized near the initial intrinsic point in the junction transition region surface and a displacement of the intrinsic point due to the oxide injected charge. A method for the determination of parameters of the model is presented. The modelling results are given for uniform surface state density increase and for an other distribution. This model is used to improve the design of memory cells devices using this phenomenon.

This paper presents a project on an electrically reprogrammable memory system in which the control of the avalanche degradation of the H FE of bipolar tetrode transistor is executed by the gate voltage. The design of a type REPROM with 1024 bits capacity having an access time better than 100 ns for a total power of 500 mW is attempted.

A detailed study of the stability of alkali-atom clusters is presented and discussed. Free clusters are produced in an unseeded adiabatic expansion and ionized by a pulsed laser beam. A tandem time-of-flight system provides a size selection of ionized species and mass spectrometry of fragments. We have investigated for sodium and potassium clusters containing up to fifty atoms: the metastable decay following ionization, the photo-induced dissociation, the collisional induced dissociation and the collisional charge exchange. Experimental evidence is shown for dissociative process involving evaporation of monomers and dimers. This is explained by the statistical unimolecular theory and by the energetics of the systems.