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The formation cross sections of ${\mathrm{Li}}^{9}$, ${\mathrm{C}}^{16}$, and ${\mathrm{N}}^{17}$ from B, C, ${\mathrm{N}}^{14}$, ${\mathrm{N}}^{15}$, ${\mathrm{O}}^{16}$, ${\mathrm{O}}^{18}$, F, Ne, Na, Mg, and Al targets bombarded with 156-MeV protons were measured by means of their neutron emission. The results were compared with calculations based on the two-step spallation mechanism. Certain reactions were shown to provide direct comparison with prompt cascade calculation. In general, the agreement between theory and experiment was good, and it is suggested that some discrepancies are attributable to the neglect of the effect of nuclear structure in the calculations. The importance of $\ensuremath{\alpha}$ emission in determining the pattern of spallation product cross section was demonstrated.

The radiation induced absorption at 3000 A in transparent methyl methacrylate is used for measuring radiation doses at each point of a volume irradiated by six radiocobalt sources. Results are given on the uniformity of dose in this volume. (auth)

The distribution of flow rate in branching vessels remains one of the less studied problems of hemodynamics. In the present paper, the authors try to approach the problem by means of a three dimensioned model. They show that an approximation of the zone of influence by an arc of a circle is in good agreement with the experimental results.

ALICE has been designed and constructed at the Institute of Nuclear Physics of Orsay, by a group of engineers (Service Electronique Accelerateurs). For the basic concept of the machine and the studies of the numerous pieces of apparatus, most of the work has been done by C. Bieth, M. P. Bourgarel, R. Gayraud, Ch. Goldstein and E. Martin. ALICE is a hybrid accelerator made of a linac injector connected to an AVF cyclotron. Ions of Z / A larger than 0.08 are supplied by the linac at 1.1 MeV per nucleon, up to Kr 8+ and Kr 7+ . These ions are further stripped of electrons in the central area of the cyclotron. Because of the high charge state of the ions after stripping, an energy larger than 5 MeV per nucleon is obtained at the exit of the cyclotron for all ions of mass smaller than A = 90. Firstly, a description is given of the cyclotron: magnetic field, generator, ion source, beam extraction, and actual performance characteristics. Secondly, the linac is briefly described: the injector at 140 kV dc, buncher, wave guide cavity, rf generator, and the main features of the 1 MeV per nucleon beam. The third point deals with the beam transport system and the stripping conditions, the energy resolution and the ion current yields of the machine. A brief account is given of the experimental facilities on the beam lines, particularly those to be used in the search for new heavy elements, i.e. on line mass spectrometer, magnetic analyser and other experimental devices.

Results are given for measurements of complete fusion cross sections in 40Ar and 84Kr induced reactions on medium and heavy targets. After complete fusion, composite nuclei decay by particle and gamma ray emission and also, in large proportions, by binary fission. Cross sections were measured on the residual nuclei and on binary fissions following full momentum transfer. In the case of Ar ions, the fusion cross section is still a large part of the total reaction cross section and the restriction due to high angular momentum is not severe. With krypton projectiles there is also a large proportion of complete fusion if the compound nucleus is in the medium masses. On the other hand with targets of bismuth and uranium a very small cross section was observed for fission events following a fusion process. An intermediate situation was found in the case of holmium and tungsten targets. Most of the reaction cross section goes into incomplete fusion channels, with a large loss of kinetic energy. A discussion is given on the dynamical aspects of the collision between two heavy nuclei.

Excitation functions have been measured for the production of polonium isotopes 202, 201, 200, 199, 198, 197 and 196 when bismuth targets are bombarded by protons in the energy range 80–155 MeV. A fast chemical separation by polonium deposition onto silver plates makes the measurements possible for the shortest half life of 1·7 min. The unknown α-emitter branching ratio was estimated and new values are given for half-lives. The results on cross sections measurements have been compared with Monte Carlo calculations made with the “two-step process” assumption.

With dark-grown synchronized Euglena on lactate medium, we have demonstrated the replication of nuclear and mitochondrial DNA. These replications are cyclically simultaneous and are found only at the beginning and during the first phase of cell division. In other phases, during a cellular generation, morphological changes in mitochondria are seen. Two different mitochondrial types are shown, following different periods of cellular cycle. Small mitochondria, very numerous and discriminated in cytoplasm, are observed during the cellular division phase. These mitochondria grow and anastomose, forming a mitochondrial network (generally peripherally located) in cells during the non-dividing phase.

The occurrence in a reversibly etiolated culture of Euglena gracilis of a structure showing the main characteristics of prolamellar body is described. Several hypotheses are given in order to attempt an explanation for the absence of this structure in most of the descriptions of other authors.

Targets of 208Pb, 232Th and 238U have been bombarded with 500 MeV 84Kr ions in an attempt to observe superheavy nuclei which could be formed by fusion. The mass identification was done in flight on recoiling nuclei. No superheavy compound nuclei were observed from any of the targets. Upper limits of formation cross sections were found of ≈ 1 νb for Pb, 5 νb for Th and 80 νb for U targets.

A la suite d’un plan de croisement hiérarchique, la variabilité génétique révélée en croisement intra- et interpopulation dans 2 populations de maïs fourrage a été analysée aux cycles Co et C1 de sélection. Les caractères étudiés sont les suivants : précocité de floraison, hauteur totale, hauteur de l’épi, longueur et largeur de la feuille de l’épi, rendement de la plante entière et teneur en matière sèche. La nature de la variabilité génétique est la même pour les 2 types de descendances : prépondérance des effets de dominance pour le rendement et à un moindre degré pour la longueur de la feuille; prépondérance des effets additifs pour tous les autres caractères. La variance d’additivité est de même importance en croisement intra- et interpopulation pour les caractères fortement héritables (mesures morphologiques et précocité), mais d’amplitude un peu plus variable pour le rendement. La corrélation entre les effets moyens des plantes mâles estimés en croisement intra- et interpopulation est positive pour tous les caractères, et d’autant plus faible que les caractères sont moins héritables. Les résultats sont en accord avec ceux de différentes expériences de sélection chez le maïs. Les conséquences de cette étude sur les méthodes de sélection sont discutées., The intra- and interpopulation genetic variability was studied in 2 forage maize populations at Co and C1 cycles of selection, from nested mating designs. The following traits were studied: flowering earliness, plant and ear heights, length and width of ear leaf, whole-plant yield and dry matter content. The nature of genetic variance was the same in intrapopulation and in interpopulation progenies: for yield and length of ear leaf, the dominance variance was significant; for the other traits, the additive variance explained most of the genetic variability. The intrapopulation and interpopulation additive variances were similar for highly heritable traits (heights and earliness) and were quite different for yield. The male plant average effects, estimated in intrapopulation and in interpopulation, were related: correlations were positive for all traits, lower for low heritable traits. Results were consistent with those reviewed from different selection experiments. Conclusions for breeding methods were then suggested.

An extraction and electrophoresis of histones from normal and starved Euglena cell nuclei allows us to show the presence of five types of histones in the two cases but a lower degree of acetylation appears in H4 histone from starved cells. It was shown that DNA repeat length from the two kinds of chromatin is comparable (225 b.p.).

Les descendances en croisement avec un testeur hybride simple de 4 populations de maïs précoce ont été récoltées en plante entière (stade ensilage) et en grain. La corrélation génétique entre le rendement en plante entière et le rendement en grain varie entre 0,71 et 0,88, selon les populations. La corrélation génétique entre les caractères de précocité de récolte fourrage et grain (teneur en matière sèche de la plante entière et humidité du grain) est assez variable d’une population à l’autre. Dans le cas d’un objectif de sélection fourrage précoce, une sélection indirecte sur les performances grain conduit à une réponse corrélative attendue sur le rendement en plante entière inférieure de 35% en moyenne au progrès attendu par une sélection directe fourrage. Une sélection exclusivement fourrage entraîne, quant à elle, une réponse corrélative attendue sur le rendement en grain inférieure de 20% en moyenne à la réponse à la sélection grain. Ces résultats montrent donc la nécessité de différencier la sélection fourrage de la sélection grain dès le début des programmes d’amélioration. Une double récolte en plante entière et en grain peut toutefois être utile pour maintenir une proportion minimale de grain en sélection fourrage. Elle peut également être nécessaire en sélection grain pour éviter une perte de variabilité trop rapide sur la biomasse aérienne totale. L’efficacité de la sélection peut alors être renforcée de façon importante par une estimation multicaractère des critères de sélection, combinant l’information apportée par les 2 types de récolte., Topcross progenies with a single cross tester from 4 early maize populations were tested for whole-plant yield (silage maturity) and for grain yield. Genetic correlation between whole plant yield and grain yield varies with populations from 0.71 to 0.88. Genetic correlations between earliness criteria of forage yield (dry matter content of whole plant) and grain yield (grain moisture) were quite different in the 4 populations. For an early forage breeding aim, an indirect selection upon grain tests led to an expected response on forage yield 35% lower on average, than direct forage selection. A selection upon forage tests led to an average of 20% less than the expected response on grain yield than grain selection. So, evidence suggests that forage selection has to be separated from grain selection from the beginning of breeding programmes. However, testing for both whole-plant yield and grain yield may be useful to keep a minimum grain content in forage selection. It can also be useful in grain selection to avoid a too fast decrease of whole-plant variability. In such cases, multicharacter estimation of breeding criteria combining both forage and grain traits can increase selection efficiency.

Authors present a new study of left ventricular local wall motion. A critical study about three methods is analysed. This original analysis method is based on the calculation of local ejection fractions from a mathematical model: a theoretical ideal systolic contour is evaluated from an ejection fraction value and for a left homogeneous ventricular contraction. The left regional wall motion is appreciated from the comparison between real systolic contour and theoretical systolic contour. At first the use problems of classical regional wall motion study are described. This presentation is to develop the mechanical and mathematical particularities of our original method. On the other one the study of computer-derived shape is to allow systematical and quick application to quantify the left ventricle contractility.

No abstract available

Using a series of mutants of Paramecium tetraurelia, we demonstrate, for the first time, changes in the internal structure of the cell membrane, as revealed by freeze-fracture, that correspond to specific single gene mutations. On the plasma membrane of Paramecium circular arrays of particles mark the sites of attachment of the tips of the intracellular secretory organelles-trichocysts. In wild-type paramecia, where attached trichocysts can be expelled by exocytosis under various stimuli, the plasma membrane array is composed of a double outer ring of particles (300 nm in diameter) and inside the ring a central rosette (fusion rosette) of particles (76 nm in diameter). Mutant nd9, characterized by a thermosensitive ability to discharge trichocysts, shows the same organization in cells grown at the permissive temperature (18 degrees C), while in cells grown at the nonpermissive temperature (27 degrees C) the rosette is missing. In mutant tam 8, characterized by normal but unattached trichocysts, and in mutant tl, completely devoid of trichocysts, no rosette is formed and the outer rings always show a modified configuration called "parentheses", also found in wild-type and in nd9 (18 degrees C) cells. From this comparison between wild type and mutants, we conclude: (a) that the formation of parentheses is a primary differentiation of the plasma membrane, independent of the presence of trichocysts, while the secondary transformation of parentheses into circular arrays and the formation of the rosette are triggered by interaction between trichocysts and plasma membranes; and (b) that the formation of the rosette is a prerequisite for trichocyst exocytosis.

Authors present a new study of left ventricular local wall motion. A critical study about three methods is analysed. This original analysis method is based on the calculation of local ejection fractions from a mathematic model: a theoretical ideal systolic contour is evaluated from an ejection fraction value and for a left homogeneous contraction ventricular. The left regional wall motion is appreciated from the comparison between real systole and theoretical systole. On the one hand, this method has been studied in theory. On the other one, it has been validated in a group of 22 patients having not any cardiac anomaly. Then its use has been compared to the two classic radial and longitudinal methods in a twenty ventriculographies group with six different contraction anomalies. Regularly, it was used on about more than 1500 valvular and coronary patients since November 1981. The results of the left ventricular function study are coherent.

In avitaminosis B12, Euglena gracilis Z is blocked in the cell cycle in the S/G2 phase. In these blocked cells, transcription and traduction go on and the amount of DNA is less than doubled and remains constant during the blockage. Chromatin clumps observed in situ with classical electron microscopic methods are always condensed in control cells but are not visualized in B12 starved cells. Two cytochemical reactions, ethanolic phosphotungstic acid and ammoniacal silver reaction, specific for lysine- or arginine-rich residues, are performed to reveal basic nuclear proteins of chromatin. With these two methods, control chromatin in situ always shows a condensed aspect, whereas the starved chromatin appears dispersed. These cytochemical differences might be considered to result from a different supramolecular organization of the two kinds of chromatin.

Quelques aspects nouveaux et originaux apportes a la physique nucleaire par les ions lourds sont presentes. Du point de vue des techniques experimentales, ce sont les faisceaux, les methodes d'identification de masse et de Z, les coincidences multiples et les collections de noyaux. Du point de vue de la connaissance en physique nucleaire, c'est une comprehension d'un micro-ensemble de matiere condensee. On decrit les grandes lignes des reactions qualifiees de "dissipatives" et les aspects de mecanique statistique appliquee au fluide nucleaire, ainsi que l'estimation de la duree des phenomenes. On montre ensuite comment les idees de base "anciennes" de la physique du debut du siecle sont fertiles pour decrire macroscopiquement les noyaux.

Vitamin B12 starvation in Euglena induces a cell cycle arrest that leads to unbalanced growth. Microfluorometry and flow cytometry analyses of cellular DNA fluorescence after Hoechst 33258 staining were performed on control and vitamin B12-deficient cells. Convergent results are obtained with both methods. Histograms that represent arrested cells are unimodal, with a mode channel value nearly twice that of the G1 control cell peak. Dispersion of fluorescence values is great, and values from 2C and over 4C are observed and discussed. It appears that vitamin B12 starvation in Euglena leads to defective DNA synthesis. Blocked cells have different DNA content, corresponding to blockade of DNA replication during the S phase. A second block prevents the onset of mitosis even for 4C cells.

In the endosymbiotic unit of Paramecium bursaria (Ciliata) and Chlorella sp. (Chlorophyceae) algae are enclosed individually in perialgal vacuoles, which do not show acid phosphatase activity and thus differ from digestive vacuoles. Both types of vacuoles have been studied by freeze-fracture. Perialgal vacuoles are nearly spherical; their membrane always fits tightly to the algal surface. The vacuole size and shape do not vary much. During division of the algal cell into four autospores the vacuole diameter only doubles. After autospore formation the vacuole invaginates around the algal daughter cells and divides. Newly formed perialgal vacuoles remain in intimate contact and exhibit characteristic attachment zones before final separation. The two fracture faces of perialgal vacuole membranes are homogeneously covered with intramembranous particles (IMPs) but rarely show signs of vesicles pinching off or fusing with the membrane, except during vacuole division. The P-faces bear more IMPs (3164 ± 625 IMP/μ m2) than the E-faces (654 ± 208 IMP/μ m2). The range of IMP density on both faces is enormous, suggesting that the membrane is not static. Membrane changes are supposed to occur simultaneously with the enlargement of the vacuole and to be caused by fusion with cytoplasmic vesicles, as the fractured necks on vacuole membranes may indicate. Digestive vacuoles in P. bursaria show significant variations in size, shape, membrane topography and IMP density, as well as signs of endocytic activity. Different vacuole populations are present in P. bursaria according to different feeding conditions: ciliates fed for a long time have small vacuoles with few IMPs (322 ±198 IMP/μ m2 on the E-faces, 1438 ± 458 IMP/μ m2on the P-faces), which are probably condensed digestive vacuoles, whereas organisms fed for a short time have larger vacuoles with highly particulate faces (680 ± 282 IMP/μ m2 on the E-faces, 2701 ± 503 IMP/μ m2 on the P-faces) and thus are supposed to be older vacuoles. The digestive vacuole membrane changes continuously. Compared to digestive vacuoles perialgal vacuoles are characterized by small size combined with high IMP density on the two fracture faces. Their IMP densities resemble those of old digestive vacuole membranes. However, it would be premature to conclude that membranes of perialgal and old digestive vacuoles are identical. Membranes of old digestive vacuoles are mainly derived from lysosomal material, which presumably does not contribute to the formation of perialgal vacuole membranes as is indicated by the small vacuole diameter; fusion with lysosomes would considerably enlarge it. The conclusions from these results are discussed in relation to the formation of perialgal vacuoles during the establishment of a stable symbiotic unit after infection of alga-free P. bursaria with the Chlorella species exsymbiotic from green paramecia.

Herpes zoster is an acute nervous system infection that commonly affects the elderly. Because the causative agent is a virus, herpes zoster is often treated symptomatically in the primary care setting. While this approach is acceptable for immunocompetent patients less than 50 years of age, it can leave older patients at greater risk of developing painful and debilitating complications such as postherpetic neuralgia. There is evidence that appropriate treatment initiated within 48 to 72 hours after the onset of the zoster eruption can decrease healing time, reduce acute pain, decrease ocular complications and may prevent the development of postherpetic neuralgia in this age group. The health care practitioner in a primary care setting is ideally placed to identify elderly clients with herpes zoster in the early stages; to consult with physicians about therapies such as steroids, antiviral agents and sympathetic nerve blocks; to monitor treatment effects; and to provide supportive therapy to those who develop postherpetic neuralgia.

Dark-grown, non-dividing Euglena gracilis Z cells were exposed for 100 h to intermittent light (15 s every 15 min darkness) and were then transferred to continuous light. During chloroplast differentiation, the development of light-harvesting and trapping properties of Photosystem II was analyzed mainly with fluorescence induction measurements in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and was associated with observations on ultrastructural organisation of developing thylakoids using thin section and freeze-fracture methods. Results showed that: (a) the synthesis of chlorophyll b and probably that of the light-harvesting chlorophyll a/b-protein complex was more reduced by intermittent light than the formation of active system II reaction centers; (b) the size of the overall photosynthetic units, i.e. the number of chlorophyll molecules per O2 molecule evolved under a regime of repetitive saturating short flashes was reduced by 2–3 compared to those developed under continuous light; (c) the lack of chlorophyll induced by intermittent light affected more specifically the size of light-harvesting antennae of system II units, the optical cross-section of which was reduced by 3–4; (d) energy transfers did not occur between these small system II units in spite of high concentrations of PS II reaction centers and of a high trapping efficiency of the absorbed energy; (e) thylakoids developed under intermittent light were not stacked; (f) particles on exoplasmic fracture faces were significantly smaller than those developed under continuous light; (g) rapid synthesis of chlorophyll (Chl a and Chl b) upon exposure to continuous light of cells first greened under intermittent light are concomittant with rapid recovery of light-harvesting properties and structural characteristics of thylakoids developed under continuous light. These structural and functional observations are consistent with the hypothesis that system II units are organized in the photosynthetic membrane as individual and discrete entities, the morphological expression of which would correspond to exoplasmic fracture face particles. They also support the model whereby energy transfers between physically connected system II units could occur across the partition between exoplasmic fracture face particles brought into contact in stacked regions.

The relationships between light-harvesting chlorophyll and reaction centers in Photosystem II were analyzed during the chloroplast development of dark-grown, non-dividing Euglena gracilis Z. Comparative measurements included light saturation of photosynthesis, oxygen evolution under flashing-light and fluorescence induction. The results obtained can be summarized as follows: (1) Photosystem II photocenters are formed in parallel with chlorophyll synthesis, but after a longer lag phase. (2) As a consequence, the chlorophyll: reaction center ratio (Emerson's type photosynthetic unit) decreases during greening. (3) This decrease is accompanied by considerable changes in the energy transfer and trapping properties of Photosystem II. Most of the initially synthesized chlorophylls are inactive in the transfer of excitations to active photochemical centers and are shared among newly formed Photosystem II photocenters; as a consequence, the number of chlorophylls functionally connected to each Photosystem II photocenter decreases and cooperativity between these centers appears. Results are discussed in terms of chlorophyll organization in developing photosynthetic membranes with reference to the lake or puddle models of photosynthetic unit organization.

En bombardant une cible d'argent par des ions carbone ou azote nous formons, par un mécanisme de transfert de nucléons, des noyaux de Z ≤ 8. Un ensemble de deux détecteurs solides montés en télescope nous permet d'identifier tous les noyaux formés et d'en mesurer l'énergie. La méthode d'identification de la masse a pour base les courbes parcoursénergie données par Northcliffe. Les bandes magnétiques d'acquisition sont traitées, événement par événement, sur ordinateur.

Ample evidence has been brought forward in recent years from several laboratories that ion transport across the chloroplast membrane leads to reversible changes in its structure (IZAWA & GOOD 1966, MURAKAMI & PACKER 1970).

Novel X-ray diffraction results of membranes from chloroplasts of Euglena are presented, together with freeze-etch images obtained concurrently. Conditions were found for sharp lamellar reflections corresponding to ordered stacking of thylakoids. The periodicity measured by diffraction agrees well with that observed by microscopy. Intensities of diffraction were analysed in order to calculate the electron density distributions across the membranes. Some arguments in favour of the preferred phases of the reflection are given. The distributions indicate firstly the presence of 25 A-wide regions where the hydrocarbon chains of the membrane lipids are concentrated. This result is discussed in terms of structural models for the chloroplast membrane. Comparison with results of freeze-etching indicates where in the density distribution are the regons inside and outside the membrane sacs. Secondly, the density distributions show maxima on the outside of the membranes only, corresponding possibly to an asymmetrical distribution of lipids.