Effects of reduced and conventional tillage on weed communities: Results of a long-term experiment in Southwestern Spain [Efeito do cultivo mínimo e plantio convencional em comunidades de plantas daninhas: Resultados de um experimento de longo prazo no sudoeste da espanha]

An important drawback in adopting minimum tillage (MT) and notillage (NT) techniques is the frequently observed weed shift promoting adapted species and achieving poorer weed control. These changes can be detected best with long-term experiments, and results might differ depending on soil characteristics and the local flora. The objectives of this work were to evaluate the effect of reduced tillage on weed seed distribution in the soil profile and to identify possible consequences on weed diversity on a long-term experiment maintained during 24 years in Seville (Spain) with three tillage systems: NT, MT and conventional tillage (CT) including moldboard plow on a vertisol. For this purpose, soil seedbanks at 0-8 cm and 8-16 cm depths were enumerated in autumn 2005 and in-field emerged plants in autumn 2005 and winter 2006. Shannon diversity index (H) and evenness (J’) were calculated for seedbank and aboveground weed communities. Total weed seed density was highest for NT and lowest for CT. Some big-seeded species, such as Chrozophora tinctorea L., showed highest seed density in CT. NT increased the relative density of Amaranthus blitoides S. Watson seeds in the seedbank and the abundance of emerged plants of Malva parviflora L., Anagallis arvensis L. and Picris echioides L. Overall, MT led to a less diverse seedbank in the 0-8 cm depth of soil than CT. The frequent drought-induced deep fractures in the expandable clay soil caused natural tillage, which probably resulted in fewer differences in weed seed and seedling densities among tillage treatments compared to what might be expected in other soil types

Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function

We present a both ultraviolet and infrared regularization independent analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta function to two loop order. We show explicitly that off-shell infrared divergences as well as the overall two loop ultraviolet divergence cancel out whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte

Properties of some conformal field theories with M-theory duals

By studying classes of supersymmetric solutions of D=11 supergravity with AdS_5 factors, we determine some properties of the dual four-dimensional N=1 superconformal field theories. For some explicit solutions we calculate the central charges and also the conformal dimensions of certain chiral primary operators arising from wrapped membranes. For the most general class of solutions we show that there is a consistent Kaluza-Klein truncation to minimal D=5 gauged supergravity. This latter result allows us to study some aspects of the dual strongly coupled thermal plasma with a non-zero R-charge chemical potential and, in particular, we show that the ratio of the shear viscosity to the entropy density has the universal value of 1/4 pi.Comment: Consistent truncation extended to include fermions. Reference added. 28 page

Exploring the key drivers of riparian woodland successional pathways across three European river reaches

"This is the peer reviewed version of the following article: Muñoz-Mas, R., V. Garófano-Gómez, I. Andrés-Doménech, D. Corenblit, G. Egger, F. Francés, M.T. Ferreira, et al. 2017. ¿Exploring the Key Drivers of Riparian Woodland Successional Pathways across Three European River Reaches.¿ Ecohydrology 10 (8). Wiley: e1888. doi:10.1002/eco.1888, which has been published in final form at https://doi.org/10.1002/eco.1888. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] Climate change and river regulation are negatively impacting riparian vegetation. To evaluate these impacts, process-based models are preferred over data-driven approaches. However, they require extensive knowledge about ecohydrological processes. To facilitate the implementation of such process-based models, the key drivers of riparian woodland successional pathways across three river reaches, in Austria, Portugal, and Spain, were explored, employing two complementary approaches. The principal component analyses highlighted the importance of the physical gradients determining the placement of the succession phases within the riparian and floodplain zones. The generalized additive models revealed that the initial and pioneer succession phases, characteristic of the colonization stage, appeared in areas highly morphodynamic, close in height and distance to the water table, and with coarse substrate, whereas elder phases within the transitional and mature stages showed incremental differences, occupying less dynamic areas with finer substrate. The Austrian site fitted well the current successional theory (elder phases appearing sequentially further up and distant), but at the Portuguese site, the tolerance of the riparian species to drought and flash flood events governed their placement. Finally, at the Spanish site, the patchy distribution of the elder phases was the remnants of formative events that reshaped the river channel. These results highlight the complex relationships between flow regime, channel morphology, and riparian vegetation. The use of succession phases, which rely on the sequential evolution of riparian vegetation as a response to different drivers, may be potentially better reproducible, within numerical process-based models, and transferable to other geographical regions.This work was supported by the IWRM Era-NET Funding Initiative through the RIPFLOW project (references ERACCT-2005-026025, ERA-IWRM/0001/2008, CGL2008-03076-E/BTE), http://www.old.iwrm-net.eu/spip.php, by the Spanish Ministry of Economy and Competitiveness through the project SCARCE (Consolider¿Ingenio 2010 CSD2009-00065), and by the project ¿Natural and anthropogenic changes in Mediterranean river drainage basins: historical impacts on rivers morphology, sedimentary flows and vegetation¿ of the Spanish MINECO (CGL2013-44917-R). Virginia Garófano-Gómez received a postdoctoral grant from the Université Blaise Pascal (now: Université Clermont Auvergne). Rui Rivaes benefited from a PhD grant (SFRH/BD/52515/2014) sponsored by Fundação para a Ciência e Tecnologia (FCT) under the FCT PhD programme FLUVIO¿River Restoration and Management. Patricia María Rodríguez González was funded by FCT through an SFRH/BPD/47140/2008 postdoctoral fellowship and through an FCT Investigator Programme grant (IF/00059/2015). The authors also thank all the colleagues and master students who contributed enthusiastically to the field campaigns of this study.Muñoz Mas, R.; Garófano-Gómez, V.; Andrés Doménech, I.; Corenblit, D.; Egger, G.; Francés, F.; Ferreira, M.... (2017). Exploring the key drivers of riparian woodland successional pathways across three European river reaches. Ecohydrology. 10(8):1-19. https://doi.org/10.1002/eco.1888S11910

Comparing Implicit, Differential, Dimensional and BPHZ Renormalisation

We compare a momentum space implicit regularisation (IR) framework with other renormalisation methods which may be applied to dimension specific theories, namely Differential Renormalisation (DfR) and the BPHZ formalism. In particular, we define what is meant by minimal subtraction in IR in connection with DfR and dimensional renormalisation (DR) .We illustrate with the calculation of the gluon self energy a procedure by which a constrained version of IR automatically ensures gauge invariance at one loop level and handles infrared divergences in a straightforward fashion. Moreover, using the $\phi^4_4$ theory setting sun diagram as an example and comparing explicitly with the BPHZ framework, we show that IR directly displays the finite part of the amplitudes. We then construct a parametrization for the ambiguity in separating the infinite and finite parts whose parameter serves as renormalisation group scale for the Callan-Symanzik equation. Finally we argue that constrained IR, constrained DfR and dimensional reduction are equivalent within one loop order.Comment: 21 pages, 2 figures, late

Factorization of integrals, defining the beta-function, into integrals of total derivatives in N=1 SQED, regularized by higher derivatives

Some calculations in supersymmetric theories, made with the higher derivative regularization, show that the beta-function is given by integrals of total derivatives. This is qualitatively explained for the N=1 supersymmetric electrodynamics in all orders.Comment: 14 page

Holographic Hydrodynamics with a Chemical Potential

We consider five-dimensional gravity coupled to a negative cosmological constant and a single U(1) gauge field, including a general set of four-derivative interactions. In this framework, we construct charged planar AdS black hole solutions perturbatively and consider the thermal and hydrodynamic properties of the plasma in the dual CFT. In particular, we calculate the ratio of shear viscosity to entropy density and argue that the violation of the KSS bound is enhanced in the presence of a chemical potential. We also compute the electrical conductivity and comment on various conjectured bounds related to this coefficient.Comment: v2: comparison to supergravity lagrangian added, references added, typos fixe

X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern