Infectivity of asexual propagules of Phytophtora infestans in sterile peat exposed to various temperature regimes

La survie de propagules asexuelles (sporanges et mycélium) du Phytophthora infestans, dans de la mousse de tourbe stérilisée à l'autoclave et exposée à diverses températures, a été évaluée par leur capacité à infecter des disques flottants de feuilles de pomme de terre. Le pouvoir infectieux des propagules dans la mousse de tourbe a été mesuré après 0, 21, 35, 63 et 79 jours d'exposition à des températures allant de -33 C à 20 C. Les propagules exposées à des températures sous le point de congélation n'étaient plus infectieuses après 21 jours. L'exposition des propagules à des températures de 15 ou de 20 C a entraîné un déclin rapide du pouvoir infectieux; aucune propagule n'était infectieuse lors du dernier échantillonnage. À l'opposé, les propagules exposées à une température de 5 C durant 79 jours sont demeurées infectieuses.Survival of asexual (sporangia and mycelium) propagules of Phytophthora infestans in autoclaved peat moss exposed to various temperatures was assessed by ability to infect floating potato leaf discs. Infectivity of propagules in peat was measured after 0, 21, 35, 63, and 79 days of exposure to temperatures ranging from -33 C to 20 C. Propagules exposed to temperatures below freezing were no longer infective after 21 days. Exposure of propagules to temperatures of 15 or 20 C resulted in a rapid decline in infectivity over time; by the final sampling date, none were infective. In contrast, propagules exposed to a temperature of 5 C for 79 days remained infective

Chiral Symmetry and light resonances in hot and dense matter

We present a study of the $\pi\pi$ scattering amplitude in the $\sigma$ and $\rho$ channels at finite temperature and nuclear density within a chiral unitary framework. Meson resonances are dynamically generated in our approach, which allows us to analyze the behavior of their associated scattering poles when the system is driven towards chiral symmetry restoration. Medium effects are incorporated in three ways: (a) by thermal corrections of the unitarized scattering amplitudes, (b) by finite nuclear density effects associated to a renormalization of the pion decay constant, and complementarily (c) by extending our calculation of the scalar-isoscalar channel to account for finite nuclear density and temperature effects in a microscopic many-body implementation of pion dynamics. Our results are discussed in connection with several phenomenological aspects relevant for nuclear matter and Heavy-Ion Collision experiments, such as $\rho$ mass scaling vs broadening from dilepton spectra and chiral restoration signals in the $\sigma$ channel. We also elaborate on the molecular nature of $\pi\pi$ resonances.Comment: 14 pages, 14 figures. Contribution to Hard Probes 2008, Illa de A Toxa, Spain, June 8th-14th 200

Multi-lingual and multi-cultural information literacy; perspectives, models and good practice

Purpose This paper reviews current approaches to, and good practice, in information literacy development in multi-lingual and multi-cultural settings, with particular emphasis on provision for international students. Design/methodology/approach A selective and critical review of published literature is extended by evaluation of examples of multi-lingual information literacy tutorials and MOOCs. Findings Multi-lingual and multi-cultural information literacy are umbrella terms covering a variety of situations and issues. This provision is of increasing importance in an increasingly mobile and multi-cultural world. This article evaluates current approaches and good practice, focusing on issues of culture vis a vis language, the balance between individual and group needs, specific and generic information literacy instruction, and models for information literacy, pedagogy and culture. Recommendations for good practice and for further research are given, Originality/value This is one of very few articles critically reviewing how information literacy development is affected by linguistic and cultural factors

A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

Crises and collective socio-economic phenomena: simple models and challenges

Financial and economic history is strewn with bubbles and crashes, booms and busts, crises and upheavals of all sorts. Understanding the origin of these events is arguably one of the most important problems in economic theory. In this paper, we review recent efforts to include heterogeneities and interactions in models of decision. We argue that the Random Field Ising model (RFIM) indeed provides a unifying framework to account for many collective socio-economic phenomena that lead to sudden ruptures and crises. We discuss different models that can capture potentially destabilising self-referential feedback loops, induced either by herding, i.e. reference to peers, or trending, i.e. reference to the past, and account for some of the phenomenology missing in the standard models. We discuss some empirically testable predictions of these models, for example robust signatures of RFIM-like herding effects, or the logarithmic decay of spatial correlations of voting patterns. One of the most striking result, inspired by statistical physics methods, is that Adam Smith's invisible hand can badly fail at solving simple coordination problems. We also insist on the issue of time-scales, that can be extremely long in some cases, and prevent socially optimal equilibria to be reached. As a theoretical challenge, the study of so-called "detailed-balance" violating decision rules is needed to decide whether conclusions based on current models (that all assume detailed-balance) are indeed robust and generic.Comment: Review paper accepted for a special issue of J Stat Phys; several minor improvements along reviewers' comment

International consensus recommendations on key outcome measures for organ preservation after (chemo)radiotherapy in patients with rectal cancer

Multimodal treatment strategies for patients with rectal cancer are increasingly including the possibility of organ preservation, through nonoperative management or local excision. Organ preservation strategies can enable patients with a complete response or near-complete clinical responses after radiotherapy with or without concomitant chemotherapy to safely avoid the morbidities associated with radical surgery, and thus to maintain anorectal function and quality of life. However, standardization of the key outcome measures of organ preservation strategies is currently lacking; this includes a lack of consensus of the optimal definitions and selection of primary end points according to the trial phase and design; the optimal time points for response assessment; response-based decision-making; follow-up schedules; use of specific anorectal function tests; and quality of life and patient-reported outcomes. Thus, a consensus statement on outcome measures is necessary to ensure consistency and facilitate more accurate comparisons of data from ongoing and future trials. Here, we have convened an international group of experts with extensive experience in the management of patients with rectal cancer, including organ preservation approaches, and used a Delphi process to establish the first international consensus recommendations for key outcome measures of organ preservation, in an attempt to standardize the reporting of data from both trials and routine practice in this emerging area.Patients with early-stage rectal cancer might potentially benefit from treatment with an organ-sparing approach, which preserves quality of life owing to avoidance of the need for permanent colostomy. Trials conducted to investigate this have so far been hampered by considerable inter-trial heterogeneity in several key features. In this Consensus Statement, the authors provide guidance on the optimal end points, response assessment time points, follow-up procedures and quality of life measures in an attempt to improve the comparability of clinical research in this area

Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV

We report the results of a study of color coherence effects in ppbar collisions based on data collected by the D0 detector during the 1994-1995 run of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8 TeV. Initial-to-final state color interference effects are studied by examining particle distribution patterns in events with a W boson and at least one jet. The data are compared to Monte Carlo simulations with different color coherence implementations and to an analytic modified-leading-logarithm perturbative calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters

Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV

We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL

Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV

We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected chi2 values for NNPD

Democracy and governance networks: compatible or not?

The relationship between representative democracy and governance networks is investigated at a theoretical level. Four conjectures about the relationship are defined. The incompatibility conjectures rests on the primacy of politics and sees governance networks as a threat. The complementarity conjecture presents governance networks as a means of enabling greater participation in the policy process and sensitivity in programme implementation. The transitional conjecture posits a wider evolution of governance forms towards network relationships. The instrumental conjecture views governance networks as a powerful means through which dominant interests can achieve their goals. Illustrative implications for theory and practice are identified, in relation to power in the policy process, the public interest, and the role of public managers. The heuristic potential of the conjectures is demonstrated through the identification of an outline research agenda