Global dynamics and stability limits for planetary systems around HD 12661, HD 38529, HD 37124 and HD 160691

In order to distinguish between regular and chaotic planetary orbits we apply a new technique called MEGNO in a wide neighbourhood of orbital parameters determined using standard two-body Keplerian fits for HD 12661, HD 38529, HD 37124 and HD 160691 planetary systems. We show that the currently announced orbital parameters place these systems in very different situations from the point of view of dynamical stability. While HD 38529 and HD 37124 are located within large stability zones in the phase space around their determined orbits, the preliminary orbits in HD 160691 are highly unstable. The orbital parameters of the HD 12661 planets are located in a border region between stable and unstable dynamical regimes, so while its currently determined orbital parameters produce stable regular orbits, a minor change within the margin of error of just one parameter may result in a chaotic dynamical system.Comment: 12 pages, 3 figures, accepted ApJ, revised version following the referee's repor

Cloned mouse cells with natural killer function and cloned suppressor T cells express ultrastructural and biochemical features not shared by cloned inducer T cells.

We have examined the morphology, cytochemistry, and biochemistry of mouse leukocyte subsets by analyzing cloned leukocyte populations specialized to perform different immunologic functions. Cloned cells expressing high-affinity plasma membrane receptors for IgE and mediating natural killer (NK) lysis and cloned antigen-specific suppressor T cells contained prominent osmiophilic cytoplasmic granules similar by ultrastructure to those of mouse basophils. Both clones also incorporated 35SO4 into granule-associated sulfated glycosaminoglycans, expressed a characteristic ultrastructural pattern of nonspecific esterase activity, incorporated exogenous [3H]5-hydroxytryptamine, and contained cytoplasmic deposits of particulate glycogen. By contrast, cloned inducer T cells lacked cytoplasmic granules and glycogen, incorporated neither 35SO4 nor [3H]5-hydroxytryptamine, and differed from the other clones in pattern of nonspecific esterase activity. These findings establish that certain cloned cells with NK activity and cloned suppressor T cells express morphologic and biochemical characteristics heretofore associated with basophilic granulocytes. However, these clones differ in surface glycoprotein expression and immunologic function, and the full extent of the similarities and differences among these populations and basophils remains to be determined

Mast cell clones: a model for the analysis of cellular maturation.

Cloned mouse mast cells resemble, by ultrastructure, immature mast cells observed in vivo. These mast cell clones can be grown in the absence of any other cells, facilitating direct investigations of their biochemistry and function. We find that cloned mast cells express plasma membrane receptors (Fc epsilon R) that bind mouse IgE with an equilibrium constant (KA) similar to that of normal mouse peritoneal mast cells. In addition, cloned mast cells do not display detectable la antigens and cannot enhance lg secretion when added to lymphocyte cultures or mediate natural killer lysis. In the presence of 1 mM sodium butyrate, cloned mast cells stop dividing and acquire abundant electron-dense cytoplasmic granules similar to those of mature mast cells. Their histamine content increases concomitant with cytoplasmic granule maturation and may exceed that of untreated mast cells by 50-fold. Unlike peritoneal mast cells, cloned mast cells incorporate 35SO4 into chondroitin sulfates rather than heparin. These findings demonstrate that, unlike fully differentiated mouse peritoneal mast cells, cloned immature mouse mast cells contain no heparin and low levels of histamine. In addition, they establish that high-affinity Fc epsilon R are expressed early in mast cell maturation, well before completion of cytoplasmic granule synthesis and mediator storage

Packing six T-joins in plane graphs

Let G be a plane graph and T an even subset of its vertices. It has been conjectured that if all T-cuts of G have the same parity and the size of every T-cut is at least k, then G contains k edge-disjoint T-joins. The case k = 3 is equivalent to the Four Color Theorem, and the cases k = 4, which was conjectured by Seymour, and k = 5 were proved by Guenin. We settle the next open case k = 6

Dothistroma septosporum: producción de esporas y condiciones climáticas

Dothistroma septosporum, the causal agent of Dothistroma needle blight is a widespread fungus which infects more than 80 species of coniferous trees through the entire world. Spreading of the infection is strongly affected by climatic factors of each locality where it is recorded. We attempt to describe the concrete limiting climatic factors necessary for the releasing of conidia of D. septosporum and to find out the timing of its spore production within the year. For this purpose we used an automatic volumetric spore trap and an automatic meteorological station. We found that a minimum daily average temperature of 10 °C was necessary for any spore production, as well as a long period of high air humidity. The values obtained in the present study were a little bit higher than those previously published, which may arise questions about a possible changing trend of the behaviour in the development of the Dothistroma needle blight causal agent. We used autoregressive integrated moving average (ARIMA) models to predict the spore counts on the base of previous values of spore counts and dew point. For a locality from Hackerovka, the best ARIMA model was 1,0,0; and for a locality from Lanzhot, the best was 3,1,0.El Dothistroma septosporum, el agente causal del tizón Dothistroma de las acículas, es un hongo ampliamente distribuido que infecta más de 80 especies de coníferas en el mundo. La propagación de la infección está fuertemente afectada por factores climáticos de cada localidad donde se registra. Tratamos de describir los factores limitantes necesarios para la liberación de los conidios de D. septosporum y averiguar el momento de la producción de esporas en el año. Para este fin se utilizó una trampa de esporas volumétrica y una estación meteorológica automáticas. Se ha encontrado que fue necesaria una temperatura media mínima diaria de 10 °C para cualquier producción de esporas, así como un largo período de alta humedad del aire. Los valores obtenidos en el presente estudio fueron un poco más altos que los publicados anteriormente, que pueden surgerir preguntas acerca de una posible tendencia cambiante de la conducta en el desarrollo del agente causal del tizón Dothistroma de las acículas. Se utilizaron modelos autorregresivos integrados media móvil (ARIMA) para predecir los conteos de esporas sobre la base de los valores anteriores de los recuentos de esporas y del punto de rocío. Para una localidad de Hackerovka, el mejor modelo ARIMA es 1.0.0 y para una localidad de Lanzhot, el mejor fue 3.1.0

Urban Agriculture Case Studies in Central Texas: From the Ground to the Rooftop

Urban agriculture is practiced in various forms and scales. Practices range from the production of edibles in small to large lots or plazas to vertical production on walls and rooftops. Produce is grown in rural locations and sold at farmers markets in urban locations or grown onsite. Efforts to produce, maintain and sell products of urban agriculture involve many participants and leaders from multiple disciplines. This chapter highlights an introduction to several urban agriculture concepts and case study examples representing activities in Central Texas, home of the Texas A&M University. These case studies highlight a modular pavilion type farmers market and urban garden in downtown Bryan, Texas, designed and built by students and faculty collaborations. The farmers market is designed to be a flexible structure to accommodate current and future needs. A rooftop crop pilot study at Texas A&M on walls and roof deck highlights the varieties grown on top of a four-storey building. The diversity of activities taking place in Central Texas exhibits concepts transferable to many locations across the world. The challenges for these projects include adaptability of crops to the Central Texas climate, structural and community support and the presence of a viable market for locally grown produce

Where are the Uranus Trojans?

The area of stable motion for fictitious Trojan asteroids around Uranus' equilateral equilibrium points is investigated with respect to the inclination of the asteroid's orbit to determine the size of the regions and their shape. For this task we used the results of extensive numerical integrations of orbits for a grid of initial conditions around the points L4 and L5, and analyzed the stability of the individual orbits. Our basic dynamical model was the Outer Solar System (Jupiter, Saturn, Uranus and Neptune). We integrated the equations of motion of fictitious Trojans in the vicinity of the stable equilibrium points for selected orbits up to the age of the Solar system of 5 billion years. One experiment has been undertaken for cuts through the Lagrange points for fixed values of the inclinations, while the semimajor axes were varied. The extension of the stable region with respect to the initial semimajor axis lies between 19.05 < a < 19.3 AU but depends on the initial inclination. In another run the inclination of the asteroids' orbit was varied in the range 0 < i < 60 and the semimajor axes were fixed. It turned out that only four 'windows' of stable orbits survive: these are the orbits for the initial inclinations 0 < i < 7, 9 < i < 13, 31 < i < 36 and 38 < i < 50. We postulate the existence of at least some Trojans around the Uranus Lagrange points for the stability window at small and also high inclinations.Comment: 15 pages, 12 figures, submitted to CMD

Dynamical Stability and Habitability of Gamma Cephei Binary-Planetary System

It has been suggested that the long-lived residual radial velocity variations observed in the precision radial velocity measurements of the primary of Gamma Cephei (HR8974, HD222404, HIP116727) are likely due to a Jupiter-like planet around this star (Hatzes et al, 2003). In this paper, the orbital dynamics of this plant is studied and also the possibility of the existence of a hypothetical Earth-like planet in the habitable zone of its central star is discussed. Simulations, which have been carried out for different values of the eccentricity and semimajor axis of the binary, as well as the orbital inclination of its Jupiter-like planet, expand on previous studies of this system and indicate that, for the values of the binary eccentricity smaller than 0.5, and for all values of the orbital inclination of the Jupiter-like planet ranging from 0 to 40 degrees, the orbit of this planet is stable. For larger values of the binary eccentricity, the system becomes gradually unstable. Integrations also indicate that, within this range of orbital parameters, a hypothetical Earth-like planet can have a long-term stable orbit only at distances of 0.3 to 0.8 AU from the primary star. The habitable zone of the primary, at a range of approximately 3.1 to 3.8 AU, is, however, unstable.Comment: 25 pages, 7 figures, 3 tables, submitted for publicatio

Impact inducted surface heating by planetesimals on early Mars

We investigate the influence of impacts of large planetesimals and small planetary embryos on the early Martian surface on the hydrodynamic escape of an early steam atmosphere that is exposed to the high soft X-ray and EUV flux of the young Sun. Impact statistics in terms of number, masses, velocities, and angles of asteroid impacts onto the early Mars are determined via n-body integrations. Based on these statistics, smoothed particle hydrodynamics (SPH) simulations result in estimates of energy transfer into the planetary surface material and according surface heating. For the estimation of the atmospheric escape rates we applied a soft X-ray and EUV absorption model and a 1-D upper atmosphere hydrodynamic model to a magma ocean-related catastrophically outgassed steam atmosphere with surface pressure values of 52 bar H2O and 11 bar CO2. The estimated impact rates and energy deposition onto an early Martian surface can account for substantial heating. The energy influx and conversion rate into internal energy is most likely sufficient to keep a shallow magma ocean liquid for an extended period of time. Higher surface temperatures keep the outgassed steam atmosphere longer in vapor form and therefore enhance its escape to space within about 0.6 Myr after its formation.Comment: submitted to A&

Degradation of isazofos in the soil environment

Field and laboratory studies were conducted to investigate the degradation of the organophosphorus insecticide isazofos (0-5-chloro-l-isopropyl-1H-l,2,4-triazol-3-ylO,O-diethyl phosphorothioate) in soil. In a 6-year field study, soil pH was an important factor influencing the degradation of isazofos inasmuch as an increased rate of degradation was observed in soils with previous isazofos applications and pH of 6.9 or more. A laboratory study of [14Clisazofos confirmed the rapid degradation of this insecticide in high pH soils. No increased degradation rate, however, was observed in sterilized high-pH soils. The availability of isazofos to microorganisms, based on sorption of isazofos to soil, seems to be an important factor influencing the degradation of isazofos in soil. Sorption coefficients were negatively correlated with isazofos degradation rate