Dispersions of ellipsoidal particles in a nematic liquid crystal

Colloidal particles dispersed in a partially ordered medium, such as a liquid crystal (LC) phase, disturb its alignment and are subject to elastic forces. These forces are long-ranged, anisotropic and tunable through temperature or external fields, making them a valuable asset to control colloidal assembly. The latter is very sensitive to the particle geometry since it alters the interactions between the colloids. We here present a detailed numerical analysis of the energetics of elongated objects, namely prolate ellipsoids, immersed in a nematic host. The results, complemented with qualitative experiments, reveal novel LC configurations with peculiar topological properties around the ellipsoids, depending on their aspect ratio and the boundary conditions imposed on the nematic order parameter. The latter also determine the preferred orientation of ellipsoids in the nematic field, because of elastic torques, as well as the morphology of particles aggregates.Comment: 31 pages, 11 figure

Natural variation at XND1 impacts root hydraulics and trade-off for stress responses in Arabidopsis

Soil water uptake by roots is a key component of plant performance and adaptation to adverse environments. Here, we use a genome-wide association analysis to identify the XYLEM NAC DOMAIN 1 (XND1) transcription factor as a negative regulator of Arabidopsis root hydraulic conductivity (Lp). The distinct functionalities of a series of natural XND1 variants and a single nucleotide polymorphism that determines XND1 translation efficiency demonstrate the significance of XND1 natural variation at species-wide level. Phenotyping of xnd1 mutants and natural XND1 variants show that XND1 modulates Lp through action on xylem formation and potential indirect effects on aquaporin function and that it diminishes drought stress tolerance. XND1 also mediates the inhibition of xylem formation by the bacterial elicitor flagellin and counteracts plant infection by the root pathogen Ralstonia solanacearum. Thus, genetic variation at XND1, and xylem differentiation contribute to resolving the major trade-off between abiotic and biotic stress resistance in Arabidopsis

Prescribed hypocaloric nutrition support for critically-ill adults

Background There are controversies about the amount of calories and the type of nutritional support that should be given to critically‐ill people. Several authors advocate the potential benefits of hypocaloric nutrition support, but the evidence is inconclusive. Objectives To assess the effects of prescribed hypocaloric nutrition support in comparison with standard nutrition support for critically‐ill adults Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, Embase and LILACS (from inception to 20 June 2017) with a specific strategy for each database. We also assessed three websites, conference proceedings and reference lists, and contacted leaders in the field and the pharmaceutical industry for undetected/unpublished studies. There was no restriction by date, language or publication status. Selection criteria We included randomized and quasi‐randomized controlled trials comparing hypocaloric nutrition support to normo‐ or hypercaloric nutrition support or no nutrition support (e.g. fasting) in adults hospitalized in intensive care units (ICUs). Data collection and analysis We used standard methodological procedures expected by Cochrane. We meta‐analysed data for comparisons in which clinical heterogeneity was low. We conducted prespecified subgroup and sensitivity analyses, and post hoc analyses, including meta‐regression. Our primary outcomes were: mortality (death occurred during the ICU and hospital stay, or 28‐ to 30‐day all‐cause mortality); length of stay (days stayed in the ICU and in the hospital); and Infectious complications. Secondary outcomes included: length of mechanical ventilation. We assessed the quality of evidence with GRADE. Main results We identified 15 trials, with a total of 3129 ICU participants from university‐associated hospitals in the USA, Colombia, Saudi Arabia, Canada, Greece, Germany and Iran. There are two ongoing studies. Participants suffered from medical and surgical conditions, with a variety of inclusion criteria. Four studies used parenteral nutrition and nine studies used only enteral nutrition; it was unclear whether the remaining two used parenteral nutrition. Most of them could not achieve the proposed caloric targets, resulting in small differences in the administered calories between intervention and control groups. Most studies were funded by the US government or non‐governmental associations, but three studies received funding from industry. Five studies did not specify their funding sources. The included studies suffered from important clinical and statistical heterogeneity. This heterogeneity did not allow us to report pooled estimates of the primary and secondary outcomes, so we have described them narratively. When comparing hypocaloric nutrition support with a control nutrition support, for hospital mortality (9 studies, 1775 participants), the risk ratios ranged from 0.23 to 5.54; for ICU mortality (4 studies, 1291 participants) the risk ratios ranged from 0.81 to 5.54, and for mortality at 30 days (7 studies, 2611 participants) the risk ratios ranged from 0.79 to 3.00. Most of these estimates included the null value. The quality of the evidence was very low due to unclear or high risk of bias, inconsistency and imprecision. Participants who received hypocaloric nutrition support compared to control nutrition support had a range of mean hospital lengths of stay of 15.70 days lower to 10.70 days higher (10 studies, 1677 participants), a range of mean ICU lengths of stay 11.00 days lower to 5.40 days higher (11 studies, 2942 participants) and a range of mean lengths of mechanical ventilation of 13.20 days lower to 8.36 days higher (12 studies, 3000 participants). The quality of the evidence for this outcome was very low due to unclear or high risk of bias in most studies, inconsistency and imprecision. The risk ratios for infectious complications (10 studies, 2804 participants) of each individual study ranged from 0.54 to 2.54. The quality of the evidence for this outcome was very low due to unclear or high risk of bias, inconsistency and imprecision We were not able to explain the causes of the observed heterogeneity using subgroup and sensitivity analyses or meta‐regression. Authors' conclusions The included studies had substantial clinical heterogeneity. We found very low‐quality evidence about the effects of prescribed hypocaloric nutrition support on mortality in hospital, in the ICU and at 30 days, as well as in length of hospital and ICU stay, infectious complications and the length of mechanical ventilation. For these outcomes there is uncertainty about the effects of prescribed hypocaloric nutrition, since the range of estimates includes both appreciable benefits and harms. Given these limitations, results must be interpreted with caution in the clinical field, considering the unclear balance of the risks and harms of this intervention. Future research addressing the clinical heterogeneity of participants and interventions, study limitations and sample size could clarify the effects of this intervention.Fil: Perman, Mario I. Hospital Italiano; ArgentinaFil: Ciapponi, Agustín. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Franco, Juan V.A.. Hospital Italiano; ArgentinaFil: Loudet, Cecilia. Universidad Nacional de La Plata; ArgentinaFil: Crivelli, Adriana. Hospital HIGA San Martín; ArgentinaFil: Garrote, Virginia. Hospital Italiano; ArgentinaFil: Perman, Gastón. Hospital Italiano; Argentin

Allelic heterogeneity and trade-off shape natural variation for response to soil micronutrient

Peer reviewedPublisher PD

1-[(4,5-Dimethyl­cyclo­hexa-1,4-dien-1-yl)sulfon­yl]-4-methyl­benzene

In the title mol­ecule, C15H18O2S, the dimethyl­cyclo­hexa­diene unit is slightly non-planar, having a folded conformation with the two double-bond planes forming a dihedral angle of 3.9 (6)°. Methyl groups of the dimethyl­cyclo­hexa­diene ring tilt away from each other, forming inter­nal C—C—C(Me) angles approximately 11° greater than the exterior angles

Influence of mutation rate on estimators of genetic differentiation - lessons from Arabidopsis thaliana

It has been brought to our attention that our paper (Kronholm et al. BMC Genetics 2010, 11: 33) may have caused some confusion for readers interested in the correct quantification of population differentiation. We feel that this issue is of some importance and wish to clarify any confusion that might have resulted

Undulation instabilities in the meniscus of smectic membranes

Using optical microscopy, phase shifting interferometry and atomic force microscopy, we demonstrate the existence of undulated structures in the meniscus of ferroelectric smectic-C* films. The meniscus is characterized by a periodic undulation of the smectic-air interface, which manifests itself in a striped pattern. The instability disappears in the untilted smectic-A phase. The modulation amplitude and wavelength both depend on meniscus thickness. We study the temperature evolution of the structure and propose a simple model that accounts for the observed undulations.Comment: Submitted to PR

Wetting and Contact Lines of Micrometer-Sized Ellipsoids

We experimentally and theoretically investigate the shapes of contact lines on the surfaces of micrometer-sized polystyrene ellipsoids at the water-air interface. By combining interferometry and optical trapping, we directly observe quadrupolar symmetry of the interface deformations around such particles. We then develop numerical solutions of the partial wetting problem for ellipsoids, and use these solutions to deduce the shapes of the corresponding contact lines and the values of the contact angles, Θc(k), as a function of the ellipsoid aspect ratio k. Surprisingly, Θc is found to decrease for increasing k suggesting that ellipsoid microscopic surface properties depend on ellipsoid aspect ratio

Drag on particles in a nematic suspension by a moving nematic-isotropic interface

We report the first clear demonstration of drag on colloidal particles by a moving nematic-isotropic interface. The balance of forces explains our observation of periodic, strip-like structures that are produced by the movement of these particles

Reflexiones sobre música actual. Entrevista a Luis Gorelik

Luis Gorelik comenzó sus estudios en el Bachillerato de Bellas Artes de la UNLP, colegio del que egresó en 1980. Desde aquel momento inició una importante y extensa carrera en el mundo de la música, destacándose como director de orquesta.&nbsp