El mecanismo del lavado en trigo

p.179-191Con el fin de estudiar la relación entre la absorción de agua por el grano previa a la cosecha y la calidad comercial, se simularon lluvias de distinta duración en varios estadios posteriores a la madurez fisiológica aplicadas a espigas de un cultivar en dos años. Los granos no incrementaron sustancialmente su contenido de humedad por absorción directa de la lluvia pero sí lo hicieron cuando las espigas permanecieron luego de estar 24 h en condiciones de alta humedad relativa. En ese caso tomaron agua libre retenida en la espiga y agua abosorbida por partes no grano que pasó al grano. Cuando se produjo un incremento de humedad en los granos disminuyó en primer lugar el Peso Hectolítrico (PH), posteriormente se opacó el aspecto externo y en último término cambió la textura interna pasando a una no vitrea

Comportamiento del trigo candeal en las condiciones ambientales del Valle Bonaerense del Río Colorado

p.101-106Con el fin de evaluar la adaptación del cultivo de trigo para fideos o trigo candeal (Triticum durum Desf.) a las condiciones ambientales del Valle Bonaerense del Río Colorado, las que incluyen riego, se realizó una serie de ensayos durante los años 1985-87. En ellos además se analizó la respuesta a la fertilización nitrogenada, tanto en rendimiento como en calidad de grano, empleando dos fuentes de nitrógeno. El cultivar Buck Candisur superó en rendimiento el resto de los comerciales, alcanzando un máximo de 6651 kg.ha-1 en 1987. Su contenido proteico fue bajo, siendo consistentemente superado por Bonaerense Quilacó. El que mostró un potencial de rendimiento algo menor, aunque no difirió estadísticamente de aquel. Ambos cultivares no difirieron en peso de mil granos o peso hectolítrico. La dosis de 100 kg de N.ha-1resultó la óptima para lograr un buen rendimiento con máxima eficiencia de uso del nitrógeno. A ese nivel no se detectaron diferencias significativas entre las fuentes de nitrógeno urea y sulfato de amonio. La dosis de 200 kg de N.ha-1 maximizó el contenido proteico

Crossover from adiabatic to sudden interaction quenches in the Hubbard model: Prethermalization and nonequilibrium dynamics

The recent experimental implementation of condensed matter models in optical lattices has motivated research on their nonequilibrium behavior. Predictions on the dynamics of superconductors following a sudden quench of the pairing interaction have been made based on the effective BCS Hamiltonian; however, their experimental verification requires the preparation of a suitable excited state of the Hubbard model along a twofold constraint: (i) a sufficiently nonadiabatic ramping scheme is essential to excite the nonequilibrium dynamics, and (ii) overheating beyond the critical temperature of superconductivity must be avoided. For commonly discussed interaction ramps there is no clear separation of the corresponding energy scales. Here we show that the matching of both conditions is simplified by the intrinsic relaxation behavior of ultracold fermionic systems: For the particular example of a linear ramp we examine the transient regime of prethermalization [M. Moeckel and S. Kehrein, Phys. Rev. Lett. 100, 175702 (2008)] under the crossover from sudden to adiabatic switching using Keldysh perturbation theory. A real-time analysis of the momentum distribution exhibits a temporal separation of an early energy relaxation and its later thermalization by scattering events. For long but finite ramping times this separation can be large. In the prethermalization regime the momentum distribution resembles a zero temperature Fermi liquid as the energy inserted by the ramp remains located in high energy modes. Thus ultracold fermions prove robust to heating which simplifies the observation of nonequilibrium BCS dynamics in optical lattices.Comment: 27 pages, 8 figures Second version with small modifications in section

Human 3D Airway Tissue Models for Real-Time Microscopy: Visualizing Respiratory Virus Spreading

Our knowledge about respiratory virus spreading is mostly based on monolayer cultures that hardly reflect the complex organization of the airway epithelium. Thus, there is a strong demand for biologically relevant models. One possibility to study virus spreading at the cellular level is real-time imaging. In an attempt to visualize virus spreading under somewhat more physiological conditions, Calu-3 cells and human primary fibroblasts were co-cultured submerged or as air-liquid interface (ALI). An influenza A virus (IAV) replicating well in cell culture, and carrying a red fluorescent protein (RFP) reporter gene was used for real-time imaging. Our three-dimensional (3D) models exhibited important characteristics of native airway epithelium including a basement membrane, tight junctions and, in ALI models, strong mucus production. In submerged models, first fluorescence signals appeared between 9 and 12 h post infection (hpi) with a low multiplicity of infection of 0.01. Virus spreading further proceeded in the immediate vicinity of infected cells. In ALI models, RFP was found at 22 hpi and later. Consequently, the progression of infection was delayed, in contrast to the submerged model. With these features, we believe that our 3D airway models can deliver new insights in the spreading of IAV and other respiratory viruses

Structural basis of human kinesin-8 function and inhibition

Kinesin motors play diverse roles in mitosis and are targets for anti-mitotic drugs. The clinical significance of these motors emphasizes the importance of understanding the molecular basis of their function. Equally, investigations into the modes of inhibition of these motors provide crucial information about their molecular mechanisms. Kif18A regulates spindle microtubules through its dual functionality – microtubule-based stepping and regulation of microtubule dynamics. We investigated the mechanism of Kif18A and its inhibition by the small molecule BTB-1. The Kif18A motor domain drives ATP-dependent plus-end microtubule gliding, and undergoes conformational changes consistent with canonical mechanisms of plus-end directed motility. The Kif18A motor domain also depolymerises microtubule plus and minus ends. BTB-1 inhibits both microtubule-based Kif18A activities. A reconstruction of BTB-1-bound, microtubule-bound Kif18A, in combination with computational modelling, identified an allosteric BTB-1 binding site near loop5, where it blocks the ATP-dependent conformational changes we characterised. Strikingly, BTB-1 binding is close to that of well-characterised Kif11 inhibitors that block tight microtubule binding, whereas BTB-1 traps Kif18A on the microtubule. Our work highlights a general mechanism of kinesin inhibition in which small molecule binding near loop5 prevents a range of conformational changes, blocking motor function

Efecto de la lluvia en el momento de la cosecha (lavado) sobre características físicas, químicas y reológicas del grano de trigo Triticum aestivum L.

p.1-6Se simularon lluvias artificiales de magnitud creciente en un lote de trigo en condiciones de ser cosechado mecánicamente (humedad menor al 11,2 por ciento). Estas lluvias disminuyeron el Peso Hectolítrico y la densidad del grano, encontrándose una correlación curvilínea altamente significativa (r igual a -0,986 y r igual a -0,981, respectivamente) entre los dos parámetros y la magnitud de las lluvias. Se ideó una escala visual que se encontró estrechamente correlacionada con ambos (r igual a 0,88 y r igual a -0,83 en igual orden) posibilitando su uso como estimador rápido del lavado en experimentos en el futuro. Otros parámetros del grano no fueron afectados como tampoco lo fue la calidad industrial

Influencia del tamaño de la semilla de trigo y sus reservas proteicas : II- el rendimiento de grano del cultivo subsecuente

p.17-24Para probar que se pueden obtener aumentos de rendimiento utilizando semillas grandes, se seleccionaron lotes del cv. Cooperación Cabildo que provenían de una red de fertilización y presentaban un rango de entre 18 y 40 g las mil semillas, y entre 9 y 18 por ciento de proteína. Con ellas se sembraron tres ensayos en dos años. El rendimiento se correlacionó positivamente con el peso de mil granos y negativamente con el porcentaje de proteína. No se obtuvo correlación del rendimiento con el peso seco de las plántulas ni con el porcentaje de emergencia. Ese mayor rendimiento se debió al incremento del número de espigas por m2

Dynamics of a Quantum Phase Transition and Relaxation to a Steady State

We review recent theoretical work on two closely related issues: excitation of an isolated quantum condensed matter system driven adiabatically across a continuous quantum phase transition or a gapless phase, and apparent relaxation of an excited system after a sudden quench of a parameter in its Hamiltonian. Accordingly the review is divided into two parts. The first part revolves around a quantum version of the Kibble-Zurek mechanism including also phenomena that go beyond this simple paradigm. What they have in common is that excitation of a gapless many-body system scales with a power of the driving rate. The second part attempts a systematic presentation of recent results and conjectures on apparent relaxation of a pure state of an isolated quantum many-body system after its excitation by a sudden quench. This research is motivated in part by recent experimental developments in the physics of ultracold atoms with potential applications in the adiabatic quantum state preparation and quantum computation.Comment: 117 pages; review accepted in Advances in Physic

Early diagnosis of acute coronary syndrome.

The diagnostic evaluation of acute chest pain has been augmented in recent years by advances in the sensitivity and precision of cardiac troponin assays, new biomarkers, improvements in imaging modalities, and release of new clinical decision algorithms. This progress has enabled physicians to diagnose or rule-out acute myocardial infarction earlier after the initial patient presentation, usually in emergency department settings, which may facilitate prompt initiation of evidence-based treatments, investigation of alternative diagnoses for chest pain, or discharge, and permit better utilization of healthcare resources. A non-trivial proportion of patients fall in an indeterminate category according to rule-out algorithms, and minimal evidence-based guidance exists for the optimal evaluation, monitoring, and treatment of these patients. The Cardiovascular Round Table of the ESC proposes approaches for the optimal application of early strategies in clinical practice to improve patient care following the review of recent advances in the early diagnosis of acute coronary syndrome. The following specific 'indeterminate' patient categories were considered: (i) patients with symptoms and high-sensitivity cardiac troponin 99th percentile but without dynamic change; and (iv) patients with symptoms and high-sensitivity troponin >99th percentile and dynamic change but without coronary plaque rupture/erosion/dissection. Definitive evidence is currently lacking to manage these patients whose early diagnosis is 'indeterminate' and these areas of uncertainty should be assigned a high priority for research