Estimation of field capacity from ring infiltrometer-drainage data

Field capacity (FC) is a parameter widely used in applied soil science. However, its in situ method of determination may be difficult to apply, generally because of the need of large supplies of water at the test sites. Ottoni Filho et al. (2014) proposed a standardized procedure for field determination of FC and showed that such in situ FC can be estimated by a linear pedotransfer function (PTF) based on volumetric soil water content at the matric potential of -6 kPa [θ(6)] for the same soils used in the present study. The objective of this study was to use soil moisture data below a double ring infiltrometer measured 48 h after the end of the infiltration test in order to develop PTFs for standard in situ FC. We found that such ring FC data were an average of 0.03 m³ m- 3 greater than standard FC values. The linear PTF that was developed for the ring FC data based only on θ(6) was nearly as accurate as the equivalent PTF reported by Ottoni Filho et al. (2014), which was developed for the standard FC data. The root mean squared residues of FC determined from both PTFs were about 0.02 m³ m- 3. The proposed method has the advantage of estimating the soil in situ FC using the water applied in the infiltration test.

Highly sensitive liquid-level sensor based on dual-wavelength double-ring fiber laser assisted by beat frequency interrogation

A highly sensitive liquid-level sensor based on dual-wavelength single-longitudinal-mode fiber laser is proposed and demonstrated. The laser is formed by exploiting two parallel arranged phase-shift fiber Bragg gratings (ps-FBGs), acting as ultra-narrow bandwidth filters, into a doublering resonators. By beating the dual-wavelength lasing output, a stable microwave signal with frequency stability better than 5 MHz is obtained. The generated beat frequency varies with the change of dual-wavelength spacing. Based on this characteristic, with one ps-FBG serving as the sensing element and the other one acting as the reference element, a highly sensitive liquid level sensor is realized by monitoring the beat frequency shift of the laser. The sensor head is directly bonded to a float which can transfer buoyancy into axial strain on the fiber without introducing other elastic elements. The experimental results show that an ultra-high liquidlevel sensitivity of 2.12 × 107 MHz/m within the measurement range of 1.5 mm is achieved. The sensor presents multiple merits including ultra-high sensitivity, thermal insensitive, good reliability and stability. © 2012 Optical Society of America.

Field hydraulic properties of an Alfisol under various fallow systems in southwestern Nigeria

The effects of various fallow management systems and cropping intensities on water infiltration were measured on an Alfisol at Ibadan in southwestern Nigeria. The objective was to determine the influence of the land use systems (a combination of crop-fallow sequences and intercropping types) on soil hydraulic properties obtained by disc permeameter and double-ring infiltration measurements. The experiment was established in 1989 as a split-plot design with four replications. The main plots were natural fallow, planted Pueraria phaseoloides and planted Leucaena leucocephala. The subplots were 1 year of maize/cassava intercrop followed by 3-year fallow (25% cropping intensity), or 2-year fallow (33% cropping intensity), or 1-year fallow (50% cropping intensity), or no fallow period (100% cropping intensity). Water infiltration rates and sorptivities were measured under saturated and unsaturated flow. Irrespective of land use, infiltration rates at the soil surface (121-324 cm h(-1)) were greater than those measured at 30 cm depth (55-144 cm h(-1)). This indicated that fewer large pores were present below 30 cm depth compared with 0-30 cm, depth. Despite some temporal variation, sorptivities with the highest mean value of 93.5 cm h(-1/2) increased as the cropping intensity decreased, suggesting a more continuous macropore system under less intensive land use systems. This was most likely due to continuous biopores created by perennial vegetation under long fallow systems. Intercropped maize and cassava yields also increased as cropping intensity decreased. The weak relationship between crop yields and hydraulic conductivity/infiltration rates suggests that the rates were not limiting.

Double Concentric Autofluorescence Ring in NR2E3-p.G56R-linked Autosomal Dominant Retinitis Pigmentosa.

Purpose: We report an unusual appearance of fundus autofluorescence (FAF) associated with NR2E3-p.G56R-linked autosomal dominant retinitis pigmentosa (ADRP).Methods: Patients were enrolled among three generations in a Swiss family. Molecular diagnosis identified a c.166G>A (p.G56R) mutation. Ophthalmic examination included fundus photography, FAF, near-infrared autofluorescence (NIA), optical coherence tomography (OCT) and visual fields (VF).Results: Fundus examination revealed a wide range of features from unremarkable to attenuated arterial caliber, clumped and spicular pigment deposits in the mid-periphery and optic nerve pallor. FAF showed a double concentric hyperautofluorescent ring: an inner perimacular ring which tended to be smaller in older patients, and an outer ring located along the vascular arcades, which appeared to extend over time towards the periphery and eventually became hypoautofluorescent. The inner and outer hyperautofluorescent rings were seen both on NIA and FAF at a similar localization. There was also a spatial correspondence between the loss of photoreceptor inner segment and outer segment junction on OCT and the area delimited by both double FAF and NIA rings. VF showed either midperipheral annular scotoma or constricted visual field loss in advanced cases, correlating with dystrophic non-functional retinal regions demarcated by the hyperautofluorescent annuli. A double ring of hyperautofluorescence was observed in all but one patient of two additional families, but not in patients harboring mutations in other ADRP genes, including PRPF3, RHO, RP1, PRPH2, PROM1 and CTRP5.Conclusions: The presence of a double concentric hyperautofluorescent ring of FAF may represent a highly penetrant early phenotypic marker of NR2E3-p.G56R-linked ADRP.

Study of biomacromolecule conformational changes by Scanning Force Microscopy

L?objectif de ce travail de thèse est l?étude des changements conformationels des biomacromolecules à l?échelle d?une molécule unique. Pour cela on a utilisé la Microscopie à Force Atomique (AFM) appliqué à l?étude des protéines et des acides nucléiques déposés sur une surface. Dans ce type de microscopie, une pointe très fine attachée à l?extrémité d?un levier est balayée au dessus d?une surface. L?interaction de la pointe avec la surface de l?échantillon induit la déflection du levier et ce phénomène permet de reconstruire la topographie de l?échantillon. Très importante dans cette technique est la possibilité de travailler en liquide. Cela permet de étudier les biomolécules en conditions quasi-physiologiques sans qu?elles perdent leur activité. On a étudié GroEL, la chaperonin de E.coli, qui est un homo oligomère avec une structure à double anneau qui joue un rôle très important dans le repliement des protéines dénaturées et celles qui viennent d?être synthétisées. En particulier on a focalisé notre attention sur la stabilité mécanique et sur les changements conformationels qui ont lieu pendant l?activité de GroEL. Une analyse détaillée des changements dans la stabilité mécanique et des effets produits par la liaison et l?hydrolyse de l?ATP est présentée dans ce travail. On a montré que le point le plus faible dans la structure de GroEL est l?interface entre les deux anneaux et que l?étape critique dans l?affaiblissement de la structure est l?hydrolyse de l?ATP. En ce qui concerne le changement conformationel, le passage d?une surface hydrophobe à hydrophile, induit par l?hydrolyse de l?ATP, a été montré. Ensuite on a étudié le changement dans la conformation et dans la topologie de l?ADN résultant de l?interaction avec des molécules spécifiques et en réponse à l?exposition des cellules de E.coli à des conditions de stress. Le niveau de surenroulement est un paramètre très sensible, de façon variée, à tous ces facteurs. Les cellules qui ont crus à de températures plus élevées que leur température optimale ont la tendance à diminuer le nombre de surenroulements négatif pour augmenter la stabilité thermique de leur plasmides. L?interaction avec des agents intercalant induit une transition d?un surenroulement négatif à un surenroulement positif d?une façon dépendante de la température. Finalement, l?effet de l?interaction de l?ADN avec des surfaces différentes a été étudié et une application pratique sur les noeuds d?ADN est présentée.<br/><br/>The aim of the present thesis work is to study the conformational changes of biomacromolecules at the single molecule level. To that end, Atomic Force Microcopy (AFM) imaging was performed on proteins and nucleic acids adsorbed onto a surface. In this microcopy technique a very sharp tip attached at the end of a soft cantilever is scanned over a surface, the interaction of the tip with the sample?s surface will induce the deflection of the cantilever and thus it will make possible to reconstruct the topography. A very important feature of AFM is the possibility to operate in liquid, it means with the sample immersed in a buffer solution. This allows one to study biomolecules in quasi-physiological conditions without loosing their activity. We have studied GroEL, the chaperonin of E.coli, which is a double-ring homooligomer which pays a very important role in the refolding of unfolded and newly synthetized polypeptides. In particular we focus our attention on its mechanical stability and on the conformational change that it undergoes during its activity cycle. A detailed analysis of the change in mechanical stability and how it is affected by the binding and hydrolysis of nucleotides is presented. It has been shown that the weak point of the chaperonin complex is the interface between the two rings and that the critical step to weaken the structure is the hydrolysis of ATP. Concerning the conformational change we have directly measured, with a nanometer scale resolution, the switching from a hydrophobic surface to a hydrophilic one taking place inside its cavity induced by the ATP hydrolysis. We have further studied the change in the DNA conformation and topology as a consequence of the interaction with specific DNA-binding molecules and the exposition of the E.coli cells to stress conditions. The level of supercoiling has been shown to be a very sensitive parameter, even if at different extents, to all these factors. Cells grown at temperatures higher than their optimum one tend to decrease the number of the negative superhelical turns in their plasmids in order to increase their thermal stability. The interaction with intercalating molecules induced a transition from positive to negative supercoiling in a temperature dependent way. The effect of the interaction of the DNA with different surfaces has been investigated and a practical application to DNA complex knots is reported.<br/><br/>Observer les objets biologiques en le touchant Schématiquement le Microscope a Force Atomique (AFM) consiste en une pointe très fine fixée a l?extrémité d?un levier Lors de l?imagerie, la pointe de l?AFM gratte la surface de l?échantillon, la topographie de celui-ci induit des déflections du levier qui sont enregistrées au moyen d?un rayon laser réfléchi par le levier. Ces donnés sont ensuit utilisés par un ordinateur pour reconstituer en 3D la surface de l?échantillon. La résolution de l?instrument est fonction entre autre de la dureté, de la rugosité de l?échantillon et de la forme de la pointe. Selon l?échantillon et la pointe utilisée la résolution de l?AFM peut aller de 0.1 A (sur des cristaux) a quelque dizaine de nanomètres (sur des cellules). Cet instrument est particulierment intéressant en biologie en raison de sa capacité à imager des échantillons immergés dans un liquide, c?est à dire dans des conditions quasiphysiologiques. Dans le cadre de ce travail nous avons étudié les changements conformationels de molécules biologiques soumises à des stimulations externes. Nous avons essentielment concentré notre attention sur des complexes protéiques nommé Chaperons Moléculaires et sur des molécules d?ADN circulaire (plasmides). Les Chaperons sont impliqués entre autre dans la résistance des organismes vivants aux stress thermiques et osmotiques. Leur activité consiste essentielment à aider les autres protéines à être bien pliés dans leur conformation finale et, en conséquence, à eviter que ils soient dénaturées et que ils puissent s?agréger. L?ADN, quant à lui est la molécule qui conserve, dans sa séquence, l?information génétique de tous les organismes vivants. Ce travail a spécifiquement concerné l?étude des changements conformationels des chaperonins suit a leur activation par l?ATP. Ces travaux ont montrés a l?échelle de molécule unique la capacité de ces protéines de changer leur surface de hydrophobique a hydrophilique. Nous avons également utilisé l?AFM pour étudier le changement du nombre des surenroulements des molécules d?ADN circulaire lors d?une exposition à un changement de température et de force ionique. Ces travaux ont permis de montrer comment la cellule regle le nombre de surenroulements dans ces molécules pour répondre et contrôler l?expression génétique même dans de conditions extrêmes. Pour les deux molécules en général, c?était très important d?avoir la possibilité de observer leur transitions d?une conformation a l?autre directement a l?échelle d?une seul molécule et, surtout, avec une résolution largement au dessous des la longueur d?onde de la lumière visible que représente le limite pour l?imagerie optique.

Cytenamide acetic acid solvate

In the crystal structure of the title compound (systematic name: 5H-dibenzo[a,d]cycloheptatriene-5-carboxamide ethanoic acid solvate), C16H13NO center dot C2H4O2, the cytenamide and solvent molecules form a hydrogen-bonded R-2(2)(8) dimer motif, which is further connected to form a centrosymmetric double ring motif arrangement. The cycloheptene ring adopts a boat conformation and the dihedral angle between the least-squares planes through the two aromatic rings is 54.7 (2)degrees.

Increased proximal urethral sensory threshold after radical pelvic surgery in women

AIM: To identify factors that potentially influence urethral sensitivity in women. PATIENTS AND METHODS: The current perception threshold was measured by double ring electrodes in the proximal and distal urethra in 120 women. Univariate analysis using Kaplan-Meier models and multivariate analysis applying Cox regressions were performed to identify factors influencing urethral sensitivity in women. RESULTS: In univariate and multivariate analysis, women who had undergone radical pelvic surgery (radical cystectomy n = 12, radical rectal surgery n = 4) showed a significantly (log rank test P < 0.0001) increased proximal urethral sensory threshold compared to those without prior surgery (hazard ratio (HR) 4.17, 95% confidence interval (CI) 2.04-8.51), following vaginal hysterectomy (HR 4.95, 95% CI 2.07-11.85), abdominal hysterectomy (HR 5.96, 95% CI 2.68-13.23), or other non-pelvic surgery (HR 4.86, 95% CI 2.24-10.52). However, distal urethral sensitivity was unaffected by any form of prior surgery. Also other variables assessed, including age, concomitant diseases, urodynamic diagnoses, functional urethral length, and maximum urethral closure pressure at rest had no influence on urethral sensitivity in univariate as well as in multivariate analysis. CONCLUSIONS: Increased proximal but unaffected distal urethral sensory threshold after radical pelvic surgery in women suggests that the afferent nerve fibers from the proximal urethra mainly pass through the pelvic plexus which is prone to damage during radical pelvic surgery, whereas the afferent innervation of the distal urethra is provided by the pudendal nerve. Better understanding the innervation of the proximal and distal urethra may help to improve surgical procedures, especially nerve sparing techniques. Neurourol. Urodynam. (c) 2006 Wiley-Liss, Inc.

Caracterización probabilística de vidrio mediante diferentes tipos de ensayos

El vidrio no puede ser tratado como un material estructural convencional desde el punto de vista de la resistencia mecánica. Su naturaleza, como material frágil, junto con la inevitable presencia de microfisuras en su superficie y las consecuencias de accidentes por posibles fallos, exigen métodos rigurosos que garanticen un cálculo seguro de los elementos estructurales de vidrio, cuya resistencia a rotura depende en gran medida del tamaño del elemento y del tipo de carga a la que está sometido. Por lo tanto, su cálculo debe basarse en conceptos probabilísticos y en criterios de mecánica de la fractura, en sustitución de un cálculo convencional de vidrio según tablas deducidas de programas experimentales y posterior aplicación del concepto de tensiones admisibles. Con el fin de analizar y comparar las características mecánicas de vidrios templados, termoendurecidos y recocidos, se realizó un amplio programa experimental de ensayos de flexión a cuatro puntos y de anillos concéntricos de pequeña superficie, seguido de un ajuste de los resultados mediante una función de distribución triparamétrica de Weibull. Glass cannot be handled as a conventional structural material from the point of view of the mechanical strength. Its nature as brittle material, together with the inevitable presence of micro-cracks on its surface and the consequences of eventual failures, demand rigorous methods to achieve a safe design for glass elements, whose stress resistance is very much dependent on the integrity of its surface, element size and loading pattern. Thus, its design must rely on probabilistic concepts and fracture mechanics criteria, substitutive of the conventional glass design based on charts derived from experimental programs and subsequent application of the admissible stress concept. In order to analyze and compare the strength characteristics of tempered, heat-strengthened and annealed glass, a large experimental programme based on four-point bending and coaxial double ring tests was performed and the results were fitted using a three-parameter Weibull cumulative distribution function.

Influencia de un recubrimiento de vinilo en la tensión de fractura del vidrio en ensayos de anillos concéntricos con gran superficie

El comportamiento post-rotura de los vidrios laminados es uno de los temas que están siendo investigados para explicar la capacidad de carga remanente tras la rotura de la primera lámina. En investigaciones previas se ha observado que en el caso de impacto humano en vidrios recocidos se llega a una capacidad hasta 3 veces superior, sin explicación clara del comportamiento estructural del conjunto. Para realizar un acercamiento a la resistencia a la rotura del vidrio laminado se ha planificado una campaña de ensayos de rotura con anillos concéntricos de grandes superficies en vidrio recocido, termoendurecido y templado, con dos series adicionales de vidrio recocido y termoendurecido con una capa de butiral adherida justo después del proceso de fabricación. Para realizar la comparación de las distribuciones de Weibull de las distintas tensiones de rotura se utiliza un proceso iterativo basado en la distribución real de tensiones obtenida con un modelo de elementos finitos ajustado con datos experimentales. Las comparaciones finales muestran un aumento apreciable de la resistencia (45%) en el caso de vidrios recocidos, y menor en el de los termoendurecidos (25%).The post-fracture behavior of the laminated glasses is one of the research topics that are being studied to explain the load capacity after the break of the first sheet. Previous experimental work have shown, that in case of human impact in annealed glasses, the capacity of bearing load it can be up to 3 times higher without clear explanation of the structural behavior of the plate. To make an approximation to the post-fracture resistance, a experimental program to test annealed, heat-tempered and toughened glass plates has been prepared. Two additional series of annealed and heattempered, with a layer of polyvinyl butyral adhered just after the manufacturing process, have also been incorporated. Coaxial Double Ring with large test surface areas Coaxial Double Ring with large test surface areas is the standard that has been followed. To make the comparison of Weibull's distributions of the different fracture stress, an iterative process based on the actual stress distribution obtained with a finite elements model updated with experimental results has been used. Final comparisons show a great stress improvement for the annealed glass plates (45 %), and a minor increment for the heat-tempered (25 %).

GroEL-GroES-mediated protein folding requires an intact central cavity

The chaperonin GroEL is an oligomeric double ring structure that, together with the cochaperonin GroES, assists protein folding. Biochemical analyses indicate that folding occurs in a cis ternary complex in which substrate is sequestered within the GroEL central cavity underneath GroES. Recently, however, studies of GroEL “minichaperones” containing only the apical substrate binding subdomain have questioned the functional importance of substrate encapsulation within GroEL-GroES complexes. Minichaperones were reported to assist folding despite the fact that they are monomeric and therefore cannot form a central cavity. Here we compare directly the folding activity of minichaperones with that of the full GroEL-GroES system. In agreement with earlier studies, minichaperones assist folding of some proteins. However, this effect is observed only under conditions where substantial spontaneous folding is also observed and is indistinguishable from that resulting from addition of the nonchaperone protein α-casein. By contrast, the full GroE system efficiently promotes folding of several substrates under conditions where essentially no spontaneous folding is observed. These data argue that the full GroEL folding activity requires the intact GroEL-GroES complex, and in light of previous studies, underscore the importance of substrate encapsulation for providing a folding environment distinct from the bulk solution.

Chaperonin filaments: The archaeal cytoskeleton?

Chaperonins are high molecular mass double-ring structures composed of 60-kDa protein subunits. In the hyperthermophilic archaeon Sulfolobus shibatae the two chaperonin proteins represent ≈4% of its total protein and have a combined intracellular concentration of >30 mg/ml. At concentrations ≥ 0.5 mg/ml purified chaperonins form filaments in the presence of Mg2+ and nucleotides. Filament formation requires nucleotide binding (not hydrolysis), and occurs at physiological temperatures in biologically relevant buffers, including a buffer made from cell extracts. These observations suggest that chaperonin filaments may exist in vivo and the estimated 4600 chaperonins per cell suggest that such filaments could form an extensive cytostructure. We observed filamentous structures in unfixed, uranyl-acetate-stained S. shibatae cells, which resemble the chaperonin filaments in size and appearance. ImmunoGold (Janssen) labeling using chaperonin antibodies indicated that many chaperonins are associated with insoluble cellular structures and these structures appear to be filamentous in some areas, although they could not be uranyl-acetate-stained. The existence of chaperonin filaments in vivo suggests a mechanism whereby their protein-folding activities can be regulated. More generally, the filaments themselves may play a cytoskeletal role in Archaea.

Magnetic polarization currents in double quantum dot devices

We investigate coherent electron transport through a parallel circuit of two quantum dots (QDs), each of which has a single tunable. energy level. Electrons tunnelling via each dot from the left lead interfere with each other at the right lead. It is shown that due to the quantum interference of tunnelling electrons the double QD device is magnetically polarized by coherent circulation of electrons on the closed path through the dots and the leads. By varying the energy level of each dot one can make the magnetic states of the device be up-, non- or down-polarized. It is shown that for experimentally accessible temperatures and applied biases the magnetic polarization currents Should be sufficiently large to observe with current nanotechnology.

Tumor necrosis factor (TNF) signaling, but not TWEAK (TNF-like weak inducer of apoptosis)-triggered cIAP1 (cellular inhibitor of apoptosis protein 1) degradation, requires cIAP1 RING dimerization and E2 binding.

Cellular inhibitor of apoptosis (cIAP) proteins, cIAP1 and cIAP2, are important regulators of tumor necrosis factor (TNF) superfamily (SF) signaling and are amplified in a number of tumor types. They are targeted by IAP antagonist compounds that are undergoing clinical trials. IAP antagonist compounds trigger cIAP autoubiquitylation and degradation. The TNFSF member TWEAK induces lysosomal degradation of TRAF2 and cIAPs, leading to elevated NIK levels and activation of non-canonical NF-kappaB. To investigate the role of the ubiquitin ligase RING domain of cIAP1 in these pathways, we used cIAP-deleted cells reconstituted with cIAP1 point mutants designed to interfere with the ability of the RING to dimerize or to interact with E2 enzymes. We show that RING dimerization and E2 binding are required for IAP antagonists to induce cIAP1 degradation and protect cells from TNF-induced cell death. The RING functions of cIAP1 are required for full TNF-induced activation of NF-kappaB, however, delayed activation of NF-kappaB still occurs in cIAP1 and -2 double knock-out cells. The RING functions of cIAP1 are also required to prevent constitutive activation of non-canonical NF-kappaB by targeting NIK for proteasomal degradation. However, in cIAP double knock-out cells TWEAK was still able to increase NIK levels demonstrating that NIK can be regulated by cIAP-independent pathways. Finally we show that, unlike IAP antagonists, TWEAK was able to induce degradation of cIAP1 RING mutants. These results emphasize the critical importance of the RING of cIAP1 in many signaling scenarios, but also demonstrate that in some pathways RING functions are not required.

The meiosis-specific recombinase hDmc1 forms ring structures and interacts with hRad51.

Eukaryotic cells encode two homologs of Escherichia coli RecA protein, Rad51 and Dmc1, which are required for meiotic recombination. Rad51, like E.coli RecA, forms helical nucleoprotein filaments that promote joint molecule and heteroduplex DNA formation. Electron microscopy reveals that the human meiosis-specific recombinase Dmc1 forms ring structures that bind single-stranded (ss) and double-stranded (ds) DNA. The protein binds preferentially to ssDNA tails and gaps in duplex DNA. hDmc1-ssDNA complexes exhibit an irregular, often compacted structure, and promote strand-transfer reactions with homologous duplex DNA. hDmc1 binds duplex DNA with reduced affinity to form nucleoprotein complexes. In contrast to helical RecA/Rad51 filaments, however, Dmc1 filaments are composed of a linear array of stacked protein rings. Consistent with the requirement for two recombinases in meiotic recombination, hDmc1 interacts directly with hRad51.