Direct, positive feedbacks produce instability in models of interrelationships among soil structure, plants and arbuscular mycorrhizal fungi

Current conceptual models of reciprocal interactions linking soil structure, plants and arbuscular mycorrhizal fungi emphasise positive feedbacks among the components of the system. However, dynamical systems with high dimensionality and several positive feedbacks (i.e. mutualism) are prone to instability. Further, organisms such as arbuscular mycorrhizal fungi (AMF) are obligate biotrophs of plants and are considered major biological agents in soil aggregate stabilization. With these considerations in mind, we developed dynamical models of soil ecosystems that reflect the main features of current conceptual models and empirical data, especially positive feedbacks and linear interactions among plants, AMF and the component of soil structure dependent on aggregates. We found that systems become increasingly unstable the more positive effects with Type I functional response (i.e., the growth rate of a mutualist is modified by the density of its partner through linear proportionality) are added to the model, to the point that increasing the realism of models by adding linear effects produces the most unstable systems. The present theoretical analysis thus offers a framework for modelling and suggests new directions for experimental studies on the interrelationship between soil structure, plants and AMF. Non-linearity in functional responses, spatial and temporal heterogeneity, and indirect effects can be invoked on a theoretical basis and experimentally tested in laboratory and field experiments in order to account for and buffer the local instability of the simplest of current scenarios. This first model presented here may generate interest in more explicitly representing the role of biota in soil physical structure, a phenomenon that is typically viewed in a more process- and management-focused context. (C) 2011 Elsevier Ltd. All rights reserved.

Directional modulation transmitter radiation pattern considerations

A pattern synthesis approach is applied to a directional modulation (DM) system. A systematic synthesis procedure is suggested which ensures optimal constellation patterns production along pre-specified communication directions, whereas simultaneously conserving energy dispersal in other directions. In this study, the properties of DM systems synthesised from Gaussian magnitude far-field radiation pattern templates are used to illustrate performance benefits with regards to DM bit error rate response compared with those achieved by a conventional steered array.

Control of biofilm growth through photodynamic treatments combined with chemical inhibitors: in vitro evaluation methods

The rock/atmosphere interface is inhabited by a complex microbial community including bacteria, algae and fungi. These communities are prominent biodeterioration agents and remarkably influence the status of stone monuments and buildings. Deeper comprehension of natural biodeterioration processes on stone surfaces has brought about a concept of complex microbial communities referred to as "subaerial biofilms". The practical implications of biofilm formation are that control strategies must be devised both for testing the susceptibility of the organisms within the biofilm and treating the established biofilm. Model multi-species biofilms associated with mineral surfaces that are frequently refractory to conventional treatment have been used as test targets. A combination of scanning microscopy with image analysis was applied along with traditional cultivation methods and fluorescent activity stains. Such a polyphasic approach allowed a comprehensive quantitative evaluation of the biofilm status and development. Effective treatment strategies incorporating chemical and physical agents have been demonstrated to prevent biofilm growth in vitro. Model biofilm growth on inorganic support was significantly reduced by a combination of PDT and biocides

Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

The Pan-STARRS1 (PS1) survey has obtained imaging in five bands (grizyP1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of MAB ∼ 23.5, of which 76 were classified as Type Ia supernovae (SNe Ia). There were 57 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or type Ic SLSNe and 12 of these have had spectra taken. Of these 12 hostless, non-Type Ia SNe, 7 were SLSNe of type Ic at redshifts between 0.5 and 1.4. This illustrates that the discovery rate of type Ic SLSNe can be maximized by concentrating on hostless transients and removing normal SNe Ia. We present data for two possible SLSNe; PS1-10pm (z = 1.206) and PS1-10ahf (z = 1.1), and estimate the rate of type Ic SLSNe to be between 3+3−2×10−53+3−2×10−53+3−2×10−5 and 8+2−1×10−58+2−1×10−58+2−1×10−5 that of the CCSN rate within 0.3 ≤ z ≤ 1.4 by applying a Monte Carlo technique. The rate of slowly evolving, type Ic SLSNe (such as SN2007bi) is estimated as a factor of 10 lower than this range.

Personal Exposure to Grass Pollen: Relating Inhaled Dose to Background Concentration

Background Very few studies on human exposure to allergenic pollen have been conducted using direct methods, with background concentrations measured at city center monitoring stations typically taken as a proxy for exposure despite the inhomogeneous nature of atmospheric pollen concentrations. A 2003 World Health Organization report highlighted the need for an improved understanding of the relation between monitoring station data and actual exposure. Objective To investigate the relation between grass pollen dose and background concentrations measured at a monitoring station, to assess the fidelity of monitoring station data as a qualitative proxy for dose, and to evaluate the ratio of dose rate to background concentration. Methods Grass pollen dose data were collected in Aarhus, Denmark, in an area where grass pollen sources were prevalent, using Nasal Air Samplers. Sample collection lasted for approximately 25 to 30 minutes and was performed at 2-hour intervals from noon to midevening under moderate exercise by 2 individuals. Results A median ratio of dose rate to background concentration of 0.018 was recorded, with higher ratio values frequently occurring at 12 to 2 pm, the time of day when grass species likely to be present in the area are expected to flower. From 4 to 8 pm, dose rate and background concentration data were found to be strongly and significantly correlated (rs = 0.81). Averaged dose rate and background concentration data showed opposing temporal trends. Conclusion Where local emissions are not a factor, background concentration data constitute a good quantitative proxy for inhaled dose. The present ratio of dose rate to background concentration may aid the study of dose–response relations.

Ampliación de la distribución de algunos peces e invertebrados durante el fenómeno El Niño 1982 - 1983

Analiza la información procedente de los cruceros 8211-12 efectuados por el BIC "Humboldt", el cual proporciona una lista de 51 especies que han ampliado su área de distribución.

L'Écho de Paris

1887/07/06 (Numéro 1206).

Le Chant du départ / Mehul, comp.. La Marseillaise / Rouget de l'Isle, comp. ; Chenal, S ; choeurs

Titre uniforme : [Le chant du départ]

Mélanges historiques sur la Champagne, l'Artois et la Picardie.

Contient : Extraits d'un livre de réception des chanoines de l'église de Troyes ; Ligues des nobles de Champagne, Vermandois, Beauvaisis, etc ; Extraits de l'obituaire de Saint-Étienne de Troyes ; Extraits des chartes de Montier-la-Celle ; Accord entre Blanche, comtesse de Champagne, et Érard de Brienne ; Pièces relatives à l'abbaye de Signy ; Accord entre Jean de Châtillon, comte de Porcien, et l'abbaye de Saint-Hubert en Ardennes ; Chartes des seigneurs de Bazoches ; Extraits du cartulaire de l'abbaye du Charme-aux-Nonnains ; Charte de Gisla pour Sainte-Gertrude de Nivelles ; Extrait du martyrologe de l'église de Laon ; Bulles et chartes relatives à la même église ; Notice sur Gaudri, évêque de Laon ; Chartes de Saint-Jean de Laon ; Chartes concernant le diocèse de Laon ; Fondation de la chapelle de La Neuville-en-Hez ; Notice d'une donation faite par Guillaume le Conquérant à Saint-Étienne de Caen ; Diplôme de Robert le Pieux pour Saint-Vaast, daté de 1039 ; Chartes concernant les comtés de Boulogne et de Ponthieu ; Extraits de chartes concernant le diocèse d'Arras ; Extraits concernant les comtes de Saint-Pol ; Extrait des titres de Saint-Vaast d'Arras ; Extraits concernant les comtes de Flandre ; Diplôme d'Eudes pour Saint-Vaast ; Charte du comte Albert pour l'abbaye de Saint-Quentin ; Charte de Baudouin, comte de Flandre, pour Saint-Pierre au Mont-Blandin ; Extraits du cartulaire du Mont-Saint-Martin ; Épitaphes diverses de l'Artois ; Funérailles de Louis de Male, comte de Flandre

Recueil de chartes de commune.

Contient : Châteauvillain ; Troyes ; Nogaro en Armagnac ; Narbonne ; La Beuvrière (cf. fol. 73) ; Reims ; Troyes ; Beaumont ; Châteauvillain (1236 ; cf. fol. 2) ; La Chapelle [d'Angillon] ; Joigny ; Lorris ; Dixmont ; Montargis ; Barcelone (cf. fol. 149) ; Selens et Saint-Aubin ; La Beuvrière (cf. fol. 14) ; Chaumont ; Saint-Bris ; Saint-Laurent-sur-Barenjon ; Voisines ; Le Moulinet ; Barlieu ; Crespy [-en-Valois] ; Montdidier ; Laon ; Soissons ; Abbeville ; Compiègne ; Saint-Quentin ; Corbie ; Saint-Josse-sur-Mer ; La Fère ; Beauvais ; Nanteuil ; Courmelles ; Breteuil ; Beaumont-en-Argonne ; Chaumont ; Saint-Omer ; Vaux près Mouzon ; Vaux, Saconin, Mercin ; Chacrise ; Tournai ; Crandelain, etc ; Ambleteuse ; Morsain, etc ; Mantes ; Ferrières ; Aizy ; Pargny ; Saint-Riquier ; Soissons ; Saint-Martin d'Issoudun (cf. fol. 182) ; Rouen ; Dreux ; Meaux ; Reims ; Chablis ; Chatillon-sur-Seine ; Sens ; Auxerre ; Cerny ; Dixmont ; Étampes ; Orléans ; Bourges ; Issoudun (cf. fol. 148) ; Beaufort-en-Vallée ; La Rochelle ; Villefranche [d'Allier] ; Montauban ; Nevers ; Castres ; Toulouse ; Habitants de la Terre d'Albigeois ; Aigues-Mortes ; Lorrez-le-Bocage ; Le Puy ; Saint-Céré ; Barcelone ; Chatillon-sur-Marne ; Raucourt et Héraucourt ; Mézières ; Chatillon-sur-Marne ; Saint-Hellier ; Coutumes d'Anjou et du Maine ; Ervy-le-Chatel ; Cerres, Montceaux, Chaussepierre ; Notice sur un ms. de Chroniques françaises, de la bibliothèque de Colbert (= Duchesne 79)