El ajuste osmótico como mecanismo de resistencia a la sequía en poblaciones áridas de P. pinaster y P. canariensis

Mechanisms of drought resistance were studied in two xeric populations of Pinus canariensis and Pinus pinaster. Seedlings were grown in a hydroponic culture for four months. Gradual controlled drought was imposed during two weeks by adding Polyethylene glycol (PEG-6000) to the growing medium. Two levels of water deficit (Psi = -1MPa, Psi = -2 MPa) and a control treatment (Psi = -0.03 MPa) were tested. Relative water content (RWC) was markedly low at the end of the experimenBoth populations showed a high capacity for osmotic adjustment in needles as shown by the osmotic index, 0.63 (1.33 MPa at 80% RWC) for P. canariensis and 0.54 (1.25 MPa at 80% RWC) for P. pinaster. Root growth and root:shoot (stem + needles) ratio were increased by water deficiOpposite patterns of relative biomass allocation were assessed between stressed and control plants. While stressed seedlings assigned more dry matter to roots, non-stressed plants showed a higher relative needle weighThe growing media caused additional stress to the plants, thus comparisons with other drought protocols should be made carefully.Se estudiaron mecanismos de resistencia a la sequía en poblaciones áridas de P.canariensis y P. pinaster. Tras cuatro meses en cultivo hidropónico, se sometió a las plantas a un tratamiento de sequía durante dos semanas añadiendo polietilenglicol (PEG-6000) a la solución. Se evaluaron dos niveles de déficit hídrico (Psi = -1MPa, Psi = -2 MPa) y un tratamiento control (Psi = -0,03 MPa). El contenido hídrico relativo (RWC) de las plántulas fue muy bajo durante todo el ensayo. Las dos poblaciones mostraron una gran capacidad de ajuste osmótico con índices de ajuste osmótico de 0,63 (ajuste osmótico de 1,33 MPa a un 80% de RWC) en P. canariensis y 0,54 (ajuste osmótico de 1,25 MPa a un 80% de RWC) en P-. pinaster. El crecimiento radical y la relación raíz:parte aérea fueron estimulados por la sequía. Se encontraron patrones de reparto de biomasa opuestos entre las plantas estresadas y las control. Mientras que las primeras destinaron más materia seca a las raíces, las no estresadas invirtieron más en biomasa foliar. El medio de cultivo causó un estrés adicional a la planta por lo que las comparaciones de ensayos de sequía utilizando PEG con otros protocolos deben de tenerlo en cuenta

At the crossroads. Management and business history in entrepreneurship research

Recent calls for a historic turn in organization studies offer the opportunity to relaunch dialogue between management and business history research. Focusing on the specific domain of entrepreneurship research, this article illustrates the potential of mutual contributions from management and business history. In doing so, it highlights how historical approaches strongly influenced the early theoretical developments within entrepreneurship and demonstrates the potential to contribute to future scholarly debates. In sum, this article brings closer together business history and management studies stressing that their different perspectives and approaches are very valuable to enriching entrepreneurship research

Relaciones históricas entre olmos y vides

In Spanish, the expression «You cannot ask an elm for pears» denotes something that is impossible. Although its origin is unknown, it can be dated back to the 1st century BC, when appeared the Latin maxim Pirum, non ulmum accedas, si cupias pira (You should go to a pear-tree for pears, not to an elm), a sentence from which we believe the Spanish saying comes. The objective of this paper is to show how the historical relationship of elms and vines can be related to these expressions, because elms did not give pears but, figuratively, did give grapes. The cultivation of vines was soon included among the domestic plants at the beginning of the Neolithic Age. During the Assyrian Empire (7th century BC), vines are represented growing up around pine-like trees. The first documentary evidence of the marriage between elms and vines is found in the Ancient Greece: a wine called Pteleaikós oinos is mentioned, which refers to the region where it was produced, Ptelea (Elm). During the Roman Ages, the cultivation of vines married to elms became more important as it is reflected in the treatises in agriculture. This technique was so common that it appears recurrently as a topic in Poetry and Drama. The classical books were copied during the Middle Ages, and only the Arabian agronomists in the Iberian Peninsula gave new evidence of the relationship between vines and elms in the 12th century. Some four hundred years later the use of elms as props for vines was rare in Spain and, although not to elms, the marriage of vines to trees lasted in the South of Spain until the 19th century. In Italy, elms and vines were even planted together in the 20th century, before the Dutch Elm Disease began to kill the plantations of trees and farmers were forced to replace them with poles.En castellano, la expresión «No se le puede pedir peras al olmo» indica algo imposible. A pesar de que su origen es desconocido, puede situarse en el siglo I A.C., cuando aparece la máxima latina Pirum, non ulmum accedas, si cupias pira (Al peral acude, no al olmo, si quieres peras), de la cual creemos que procede la expresión española. En este trabajo se pretende mostrar que la relación histórica de los olmos y las vides puede estar relacionada con estas expresiones en la medida en que los olmos no daban peras mas, en sentido figurado, daban uvas. La vid fue una de las primeras plantas cultivadas ya desde el comienzo del Neolítico. En el Imperio Asirio (s. VII A.C.), las vides aparecen representadas creciendo alrededor de árboles que se asemejan a pinos. La primera evidencia documental del maridaje de olmos y vides la encontramos en la Grecia Clásica, donde se menciona un vino llamado Pteleaikós oinos que hace referencia a la región dónde se producía, Ptelea (Olmo). Durante la época Romana el cultivo de las vides maridadas a los olmos adquiere mayor importancia, como se refleja en los tratados de agricultura. La práctica fue tan común que aparece de modo recurrente como tópico en la literatura. Los textos clásicos son copiados durante la Edad Media, y sólo los agrónomos árabes de la península Ibérica proporcionan nuevas evidencias de la relación entre vides y olmos ya en el siglo XII. Cuatro siglos después la utilización de olmos como tutores de las vides era rara en España, pero el maridaje de las vides con árboles, aunque no olmos, duró en el Sur de España hasta el siglo XIX. Sin embargo en Italia olmos y vides se plantaban juntos incluso en el siglo XX, antes de que la grafiosis comenzara a matar las plantaciones de árboles y los agricultores se vieran obligados a sustituirlos por postes

Quantum Fluids in Thermodynamic Geometry

In this work, the Thermodynamic Geometry (TG) of quantum fluids (QF) is analyzed. We present results for two models. The first one is a quantum hard-sphere fluid (QHS) whose Helmholtz free energy is obtained from Path Integrals Monte Carlo simulations (PIMC). It is found that due to quantum contributions in the thermodynamic potential, the anomaly found in TG for the classical hard-sphere fluid related to the sign of the scalar curvature, is now avoided in a considerable region of the thermodynamic space. The second model is a semi-classical square-well fluid (QSW), described by a quantum hard-sphere repulsive interaction coupled with a classical attractive square-well contribution. Behavior of the semi-classical curvature scalar as a function of the thermal de Broglie wavelength $\lambda_B$ is analyzed for several attractive-potential ranges, and description of the semi-classical R-Widom lines defined by the maxima of the curvature scalar, are also obtained and compared with classical results for different square-well ranges.Comment: 9 pages, 8 figure

Evolution of EEG motor rhythms after spinal cord injury: A longitudinal study

Spinal cord injury (SCI) does not only produce a lack of sensory and motor function caudal to the level of injury, but it also leads to a progressive brain reorganization. Chronic SCI patients attempting to move their affected limbs present a significant reduction of brain activation in the motor cortex, which has been linked to the deafferentation. The aim of this work is to study the evolution of the motor-related brain activity during the first months after SCI. Eighteen subacute SCI patients were recruited to participate in bi-weekly experimental sessions during at least two months. Their EEG was recorded to analyze the temporal evolution of the event-related desynchronization (ERD) over the motor cortex, both during motor attempt and motor imagery of their paralyzed hands. The results show that the a and ß ERD evolution after SCI is negatively correlated with the clinical progression of the patients during the first months after the injury. This work provides the first longitudinal study of the event-related desynchronization during the subacute phase of spinal cord injury. Furthermore, our findings reveal a strong association between the ERD changes and the clinical evolution of the patients. These results help to better understand the brain transformation after SCI, which is important to characterize the neuroplasticity mechanisms involved after this lesion and may lead to new strategies for rehabilitation and motor restoration of these patients

The Double Quasar HE1104-1805: a case study for time delay determination with poorly sampled lightcurves

We present a new determination of the time delay of the gravitational lens system HE1104-1805 ('Double Hamburger') based on a previously unpublished dataset. We argue that the previously published value of dt_(A-B)=0.73 years was affected by a bias of the employed method. We determine a new value of dt_(A-B)=0.85+/-0.05 years (2 sigma confidence level), using six different techniques based on non interpolation methods in the time domain. The result demonstrates that even in the case of poorly sampled lightcurves, useful information can be obtained with regard to the time delay. The error estimates were calculated through Monte Carlo simulations. With two already existing models for the lens and using its recently determined redshift, we infer a range of values of the Hubble parameter: Ho=48+/-4 km/s Mpc^-1 (2 sigma) for a singular isothermal ellipsoid (SIE) and Ho=62+/-4 km/s Mpc^-1 (2 sigma) for a constant mass-to-light ratio plus shear model (M/L+gamma). The possibly much larger errors due to systematic uncertainties in modeling the lens potential are not included in this error estimate.Comment: 11 pages, 15 figures, accepted by Astronomy and Astrophysic

Cooperation between passive and active silicon transporters clarifies the ecophysiology and evolution of biosilicification in sponges

Este artículo contiene 14 páginas, 6 figuras.The biological utilization of dissolved silicon (DSi) influences ocean ecology and biogeochemistry. In the deep sea, hexactinellid sponges are major DSi consumers that remain poorly understood. Their DSi consumption departs from the Michaelis-Menten kinetics of shallow-water demosponges and appears particularly maladapted to incorporating DSi from the modest concentrations typical of the modern ocean. Why did sponges not adapt to the shrinking DSi availability that followed diatom expansion some 100 to 65 million years ago? We propose that sponges incorporate DSi combining passive (aquaglyceroporins) and active (ArsB) transporters, while only active transporters (SITs) operate in diatoms and choanoflagellates. Evolution of greater silicon transport efficiency appears constrained by the additional role of aquaglyceroporins in transporting essential metalloids other than silicon. We discuss the possibility that lower energy costs may have driven replacement of ancestral SITs by less efficient aquaglyceroporins, and discuss the functional implications of conservation of aquaglyceroporin-mediated DSi utilization in vertebrates.This research was completed mostly by funds from the SponGES H2020 grant (BG-01-2015.2, agreement number 679849-2) to M.M. and A.R. and from Fisheries and Oceans Canada Strategic Program for Ecosystem-Based Research and Advice (SPERA) and International Governance Strategy (IGS) projects awarded to L.B. and E.K. This study also benefitted from funding by a PBS grant (MINECO CTM2015-67221-R) to M.M. This study is in memory of Hans Tore Rapp, who passed away on 7 March 2020, and who was the main coordinator of the H2020 SponGES project that has made this research possible.Peer reviewe

Meropenem heteroresistance in clinical isolates of OXA-48–producing Klebsiella pneumoniae

OXA-48–producing Klebsiella pneumoniae isolates often show growth of colonies within inhibition zones in carbapenem diffusion assays. The nature of these colonies was investigated in a series of clinical isolates of OXA-48–producing K. pneumoniae obtained in the context of a hospital outbreak, and they were found to be persistent colonies that reproduced again the same phenotype when they were collected and tested in diffusion assays again. The frequency of mutations conferring resistance to meropenem (8 µg/mL) was determined for the same isolates. The average mutation frequency was 5.47·10-6 (range: 2.59·10-8–5.87·10-5), and the analysis of several resistant mutants showed that all of them had mutations in the ompK36 porin gene. Heteroresistance was investigated using population analysis profiling. The profiles were compatible with mutation frequency assays, and all the colonies analyzed were resistant mutants. In OXA-48–producing K. pneumoniae, the growth of persisters seems to be specific of diffusion assays

Classification of uterine anomalies by three-dimensional ultrasonography using ESHRE/ESGE criteria: inter-observer variability.

Objective: To evaluate the interobserver repeatability of the coronal view measurements and classification of the uterine malformations (UM) according to the ESHRE/ESGE consensus by transvaginal three-dimensional ultrasound (3D US). Methods: 89 transvaginal 3D volumes acquired during the last two years at Delta Ecografía in Madrid, Spain, were selected from our archive by convenience sampling. Two expert operators blinded from each other, performed post-hoc analysis using render mode and multiplanar-VCI navigation. Uterine wall thickness at the fundus, indentation of the cavity and indentation of the fundus were measured, classified and sub-classified following the recommendations of the ESHRE/ESGE consensus. The reproducibility of interobserver measurements and classification was examined by calculating intraclass correlation coefficients (ICC) and their 95% confidence intervals (CI) and kappa statistic (k).pre-print261 K