Cloning crops in a CELSS via tissue culture: Prospects and problems

Micropropagation is currently used to clone fruits, nuts, and vegetables and involves controlling the outgrowth in vitro of basal, axillary, or adventitious buds. Following clonal multiplication, shoots are divided and rooted. This process has greatly reduced space and energy requirements in greenhouses and field nurseries and has increased multiplication rates by greater than 20 fold for some vegetatively propagated crops and breeding lines. Cereal and legume crops can also be cloned by tissue culture through somatic embryogenesis. Somatic embryos can be used to produce 'synthetic seed', which can tolerate desiccation and germinate upon rehydration. Synthetic seed of hybrid wheat, rice, soybean and other crops could be produced in a controlled ecological life support system. Thus, yield advantages of hybreds over inbreds (10 to 20 percent) could be exploited without having to provide additional facilities and energy for parental-line and hybrid seed nurseries

Jupiter's radiation belts: Can Pioneer 10 survive?

Model calculations of Jupiter's electron and proton radiation belts indicate that the Galilean satellites can reduce particle fluxes in certain regions of the inner magnetosphere by as much as six orders of magnitude. Average fluxes should be reduced by a factor of 100 or more along the Pioneer 10 trajectory through the heart of Jupiter's radiation belts in early December. This may be enough to prevent serious radiation damage to the spacecraft

Scaling behavior of interactions in a modular quantum system and the existence of local temperature

We consider a quantum system of fixed size consisting of a regular chain of $n$-level subsystems, where $n$ is finite. Forming groups of $N$ subsystems each, we show that the strength of interaction between the groups scales with $N^{- 1/2}$. As a consequence, if the total system is in a thermal state with inverse temperature $\beta$, a sufficient condition for subgroups of size $N$ to be approximately in a thermal state with the same temperature is $\sqrt{N} \gg \beta \bar{\delta E}$, where $\bar{\delta E}$ is the width of the occupied level spectrum of the total system. These scaling properties indicate on what scale local temperatures may be meaningfully defined as intensive variables. This question is particularly relevant for non-equilibrium scenarios such as heat conduction etc.Comment: 7 pages, accepted for publication in Europhysics Letter

Absorption of trapped particles by Jupiter's moons

Absorption effects of the four innermost moons in the radial transport equations for electrons and protons in Jupiter's magnetosphere are presented. The phase space density n at 2 R sub J for electrons with equatorial pitch angles less than 69 deg is reduced by a factor of 4.2 x 1000 when lunar absorption is included in the calculation. For protons with equatorial pitch angles less than 69 deg, the corresponding reduction factor is 3.2 x 100000. The effect of the satellites becomes progressively weaker for both electrons and protons as equatorial pitch angles of pi/2 are approached, because the likelihood of impacting a satellite becomes progressively smaller. The large density decreases which we find at the orbits of Io, Europa, and Ganymede result in corresponding particle flux decreases that should be observed by spacecraft making particle measurements in Jupiter's magnetosphere. The characteristic signature of satellite absorption should be a downward pointing cusp in the flux versus radius curve at the L-value corresponding to each satellite

Le Parc naturel urbain en Suisse : une utopie? Approche philosophique pour dépasser l'opposition ville/nature

Cet article examine le rapport ville/nature par le prisme de la politique des parcs naturels en Suisse. Partant d’une approche philosophique de l’idée de nature, il s’efforce de montrer que la création du Parc national suisse en 1914 s’inscrit dans une opposition sous-jacente entre l’homme et la nature. Avec l’évolution ultérieure de la législation en 2006, cette dichotomie subsiste dans la relation ville/nature. La discussion sur la catégorie de parc naturel urbain permet ensuite de proposer un dépassement de cette opposition en s’appuyant sur la phénoménologie et la pensée critique telles que développées par G. Böhme, A. Berque et V. Plumwood. Un tel dépassement se traduit par une conception intégrative de la nature en ville. Notre proposition s’articule ainsi autour de l’idée d’une nature en relation d’intériorité ou en relation d’identification avec la ville. Pour les acteurs impliqués dans la définition des parcs naturels en Suisse, elle suppose un décentrement autorisant un regard moins hostile sur la ville.Dieser Artikel untersucht das Verhältnis zwischen Stadt und Natur anhand der schweizerischen Gesetzgebung der Naturparks. Der philosophische Ansatz ist der Begriff Natur. Damit wird gezeigt, dass die Schaffung des ersten Naturparks Europas in 1914 – der Schweizerische Nationalpark – auf einen Gegensatz zwischen Mensch und Natur beruht. Mit der Weiterentwicklung der Gesetzgebung besteht jedoch die Entgegensetzung in der Form Stadt/Natur weiter. Die Debatte über die Kategorie des städtischen Naturparks ermöglicht dann mit Hilfe der Phänomenologie und der kritischen Philosophie, wie sie von G. Böhme, A. Berque und V. Plumwood vertreten werden, diesen Gegensatz zu überwinden. Eine solche Überwindung geschieht aber erst durch eine integrative Auffassung der Natur innerhalb der Stadt. Unser Vorschlag basiert auf der Idee einer Natur in innerer Beziehung oder in identifizierender Beziehung zur Stadt. Für die Akteure, die in der Definition der Naturparks involviert sind, bedeutet dies eine Dezentrierung, die einen weniger feindlichen Blick auf die Stadt erlaubt.This paper examines the city/nature relationship through the lens of the policy of natural parks in Switzerland. Using a philosophical approach of the idea of nature, it shows that the creation of the Swiss National Park was linked with an underlying opposition between human and nature. After the evolution of the legal framework in 2006, this dichotomy remains vivid in the city/nature relationship. Discussing the category of urban natural park, our proposition intends to exceed this dichotomy using philosophical concepts of phenomenoly and critical thought as elaborated by G. Böhme, A. Berque and V. Plumwood. Our proposal is thereby structured around the idea of nature in interiority relationship or in relation of identification with the city. Such approaches allow an integrative conception of nature and city. It implies, for the actors involved in defining the natural parks in Switzerland, a decentering allowing a less hostile view of the city

Le Parc naturel urbain en Suisse : une utopie? Approche philosophique pour dépasser l'opposition ville/nature

This paper examines the city/nature relationship through the lens of the policy of natural parks in Switzerland. Using a philosophical approach of the idea of nature, it shows that the creation of the Swiss National Park was linked with an underlying opposition between human and nature. After the evolution of the legal framework in 2006, this dichotomy remains vivid in the city/nature relationship. Discussing the category of urban natural park, our proposition intends to exceed this dichotomy using philosophical concepts of phenomenoly and critical thought as elaborated by G. Böhme, A. Berque and V. Plumwood. Our proposal is thereby structured around the idea of nature in interiority relationship or in relation of identification with the city. Such approaches allow an integrative conception of nature and city. It implies, for the actors involved in defining the natural parks in Switzerland, a decentering allowing a less hostile view of the city

Star-shaped Local Density of States around Vortices in a Type II Superconductor

The electronic structure of vortices in a type II superconductor is analyzed within the quasi-classical Eilenberger framework. The possible origin of a sixfold ``star'' shape of the local density of states, observed by scanning tunneling microscope experiments on NbSe$_2$, is examined in the light of the three effects; the anisotropic pairing, the vortex lattice, and the anisotropic density of states at the Fermi surface. Outstanding features of split parallel rays of this star are well explained in terms of an anisotropic $s$-wave pairing. This reveals a rich internal electronic structure associated with a vortex core.Comment: 4 pages, REVTeX, 3 figures available upon reques

Van Allen Probes show that the inner radiation zone contains no MeV electrons: ECT/MagEIS data

Abstract We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the Energetic Particle, Composition, and Thermal Plasma/Magnetic Electron Ion Spectrometer (MagEIS) sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons \u3e900 keV were observed with equatorial fluxes above background (i.e., \u3e0.1 el/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes \u3c200 keV exceeded the AE9 model 50% fluxes and were lower than the higher-energy model fluxes. Phase space density radial profiles for 1.3 ≤ L* \u3c 2.5 had mostly positive gradients except near L*~2.1, where the profiles for μ = 20–30 MeV/G were flat or slightly peaked. The major result is that MagEIS data do not show the presence of significant fluxes of MeV electrons in the inner zone while current radiation belt models and previous publications do

A Coupled Map Lattice Model for Rheological Chaos in Sheared Nematic Liquid Crystals

A variety of complex fluids under shear exhibit complex spatio-temporal behaviour, including what is now termed rheological chaos, at moderate values of the shear rate. Such chaos associated with rheological response occurs in regimes where the Reynolds number is very small. It must thus arise as a consequence of the coupling of the flow to internal structural variables describing the local state of the fluid. We propose a coupled map lattice (CML) model for such complex spatio-temporal behaviour in a passively sheared nematic liquid crystal, using local maps constructed so as to accurately describe the spatially homogeneous case. Such local maps are coupled diffusively to nearest and next nearest neighbours to mimic the effects of spatial gradients in the underlying equations of motion. We investigate the dynamical steady states obtained as parameters in the map and the strength of the spatial coupling are varied, studying local temporal properties at a single site as well as spatio-temporal features of the extended system. Our methods reproduce the full range of spatio-temporal behaviour seen in earlier one-dimensional studies based on partial differential equations. We report results for both the one and two-dimensional cases, showing that spatial coupling favours uniform or periodically time-varying states, as intuitively expected. We demonstrate and characterize regimes of spatio-temporal intermittency out of which chaos develops. Our work suggests that such simplified lattice representations of the spatio-temporal dynamics of complex fluids under shear may provide useful insights as well as fast and numerically tractable alternatives to continuum representations.Comment: 32 pages, single column, 20 figure

Comparison between wind waves at sea and in the laboratory

Correlations between laboratory and geophysical data are presented for certain statistical properties of wind waves. The parameters chosen include: (i) relationships between wave height and the height of the highest one-third or one-tenth waves, as given by a Rayleigh probability distribution, and (ii) amplitude spectra for waves, as given by Phillips\u27 equilibrium theory. The correlation between laboratory results and geophysical data is satisfactory over a wide range of wave size