Stability of the distal radioulnar joint with and without activation of forearm muscles

The purpose of this study was to quantify the effect of the flexor carpi ulnaris and the extensor carpi ulnaris muscles on distal radioulnar joint stability. The anteroposterior ulnar head translation in relation to the radius was measured sonographically when the forearm was in a neutral resting position and when the hand was actively pressed on to a surface, with and without intentional flexor carpi ulnaris and extensor carpi ulnaris activation, while also being monitored by an electromyogram. Data on 40 healthy participants indicated a mean anteroposterior translation in the distal radioulnar joint of 4.1 mm (SD 1.08) without and 1.2 mm (SD 0.54) with muscle activation. Our results indicate that intentional ulnar forearm muscle activation results in 70% less anteroposterior ulnar head translation and greater distal radioulnar joint stability. Therefore, the flexor carpi ulnaris and extensor carpi ulnaris muscles serve as dynamic stabilizers of the distal radioulnar joint. This finding may be clinically significant since ulnar forearm muscles strengthening may increase distal radioulnar joint stability

Interplay between motility and cell-substratum adhesion in amoeboid cells

The effective migration of amoeboid cells requires a fine regulation of cell-substratum adhesion. These entwined processes have been shown to be regulated by a host of biophysical and biochemical cues. Here, we reveal the pivotal role played by calcium-based mechanosensation in the active regulation of adhesion resulting in a high migratory adaptability. Using mechanotactically driven Dictyostelium discoideum amoebae, we uncover the existence of optimal mechanosensitive conditions—corresponding to specific levels of extracellular calcium—for persistent directional migration over physicochemically different substrates. When these optimal mechanosensitive conditions are met, noticeable enhancement in cell migration directionality and speed is achieved, yet with significant differences among the different substrates. In the same narrow range of calcium concentrations that yields optimal cellular mechanosensory activity, we uncovered an absolute minimum in cell-substratum adhesion activity, for all considered substrates, with differences in adhesion strength among them amplified. The blocking of the mechanosensitive ion channels with gadolinium—i.e., the inhibition of the primary mechanosensory apparatus—hampers the active reduction in substrate adhesion, thereby leading to the same undifferentiated and drastically reduced directed migratory response. The adaptive behavioral responses of Dictyostelium cells sensitive to substrates with varying physicochemical properties suggest the possibility of novel surface analyses based on the mechanobiological ability of mechanosensitive and guidable cells to probe substrates at the nanometer-to-micrometer level.SUTD-MIT International Design Centre (IDC) (IDG31400104

Inelastic neutron and x-ray scattering as probes of the sign structure of the Fe-pnictide superconducting gap

Neutron spin-flip scattering observations of a resonance in the superconducting state is often taken as evidence of an unconventional superconducting state in which the gap changes sign $\Delta(k+Q)=-\Delta(k)$ for momentum transfers $Q$ which play an important role in the pairing. Recently questions regarding this identification for the Fe-pnictide superconductors have been raised and it has been suggested that $\Delta(k+Q)=\Delta(k)$. Here we propose that inelastic neutron or x-ray scattering measurements of the spectral weight of a phonon of momentum $Q$ can distinguish between these two pairing scenarios.Comment: 4 pages, 4 figure

Contact-controlled amoeboid motility induces dynamic cell trapping in 3D-microstructured surfaces.

On flat substrates, several cell types exhibit amoeboid migration, which is characterized by restless stochastic successions of pseudopod protrusions. The orientation and frequency of new membrane protrusions characterize efficient search modes, which can respond to external chemical stimuli as observed during chemotaxis in amoebae. To quantify the influence of mechanical stimuli induced by surface topography on the migration modes of the amoeboid model organism Dictyostelium discoideum, we apply high resolution motion analysis in microfabricated pillar arrays of defined density and geometry. Cell motion is analyzed by a two-state motility-model, distinguishing directed cellular runs from phases of isotropic migration that are characterized by randomly oriented cellular protrusions. Cells lacking myosin II or cells deprived of microtubules show significantly different behavior concerning migration velocities and migrational angle distribution, without pronounced attraction to pillars. We conclude that microtubules enhance cellular ability to react with external 3D structures. Our experiments on wild-type cells show that the switching from randomly formed pseudopods to a stabilized leading pseudopod is triggered by contact with surface structures. These alternating processes guide cells according to the available surface in their 3D environment, which we observed dynamically and in steady-state situations. As a consequence, cells perform "home-runs" in low-density pillar arrays, crawling from pillar to pillar, with a characteristic dwell time of 75 s. At the boundary between a flat surface and a 3D structured substrate, cells preferentially localize in contact with micropillars, due to the additionally available surface in the microstructured arrays. Such responses of cell motility to microstructures might open new possibilities for cell sorting in surface structured arrays

Alleinerziehende in Österreich: Lebensbedingungen und Armutsrisiken

Im Jahr 2009 gab es in Österreich 114.400 Alleinerziehende mit Kindern unter 15 Jahren, davon waren 92% alleinerziehende Mütter und 8% alleinerziehende Väter. Jede achte Frau (14%) und einer von hundert Männern (1%) mit Kindern unter 15 Jahren ist somit Alleinerzieher/-in. Die in Kooperation zwischen den Instituten für Soziologie der Universität Wien und der Universität Linz erstellte Studie „Alleinerziehende in Österreich“ verfolgt das Ziel, die Lebenssituation Alleinerziehender und deren spezifische Herausforderungen darzustellen und zu analysieren und dabei besonders auf die Situation alleinerziehender Mütter einzugehen. Darüber hinaus werden Armuts- und Deprivationsrisiken von Alleinerzieherinnen und ihren Kindern aufgezeigt sowie unterschiedliche Interventionen zur Bekämpfung der Armutsgefährdung in Ein-Eltern-Familien skizziert

In vivo imaging and quantitative analysis of leukocyte directional migration and polarization in inflamed tissue

Directional migration of transmigrated leukocytes to the site of injury is a central event in the inflammatory response. Here, we present an in vivo chemotaxis assay enabling the visualization and quantitative analysis of subtype-specific directional motility and polarization of leukocytes in their natural 3D microenvironment. Our technique comprises the combination of i) semi-automated in situ microinjection of chemoattractants or bacteria as local chemotactic stimulus, ii) in vivo near-infrared reflected-light oblique transillumination (RLOT) microscopy for the visualization of leukocyte motility and morphology, and iii) in vivo fluorescence microscopy for the visualization of different leukocyte subpopulations or fluorescence-labeled bacteria. Leukocyte motility parameters are quantified off-line in digitized video sequences using computer-assisted single cell tracking. Here, we show that perivenular microinjection of chemoattractants [macrophage inflammatory protein-1alpha (MIP-1alpha/Ccl3), platelet-activating factor (PAF)] or E. coli into the murine cremaster muscle induces target-oriented intravascular adhesion and transmigration as well as polarization and directional interstitial migration of leukocytes towards the locally administered stimuli. Moreover, we describe a crucial role of Rho kinase for the regulation of directional motility and polarization of transmigrated leukocytes in vivo. Finally, combining in vivo RLOT and fluorescence microscopy in Cx3CR1(gfp/gfp) mice (mice exhibiting green fluorescent protein-labeled monocytes), we are able to demonstrate differences in the migratory behavior of monocytes and neutrophils.Taken together, we propose a novel approach for investigating the mechanisms and spatiotemporal dynamics of subtype-specific motility and polarization of leukocytes during their directional interstitial migration in vivo

Sistema de ecuaciones de producción y crecimiento de Pinus taeda L. con variables asociadas a las podas

It were adjusted stand yield functions and dinamic growth models, that compose a compatible system of equations, that include regressors variables associated with prune intensity, beside age, stand density and site index. The data set come from a trial in a Pinus taeda L. plantation, with ages between 4 and 9 years. The response variables analyzed were basal area and volume per hectare. For both variables the models obtained produced lower production and young growth values when the prunes were intensified. Also, it were obtained more precision and a slightly better adjusted quality than equations with excellent statistic behavior without prune variables. The utilization of predictive area basal functions allows to obtain results for quadratic mean diameter according to prune intensity. These functions could be easy employed as a tool to decide when and how much of green branches prune in relation with the production objective. The obtained models appear interesting to develop new regional growth simulation programs of Pinus taeda that include prunes applied in intensive silvicultural systems of forest production.Se ajustaron modelos de producción y de proyección del crecimiento de rodal completo, que forman un sistema de ecuaciones compatibles entre sí, incluyendo variables regresoras asociadas con la intensidad de podas, además de la edad, la densidad y el índice de sitio. Se utilizaron datos de un ensayo de Pinus taeda L., con edades entre 4 y 9 años. Las variables respuestas analizadas fueron el área basimétrica y el volumen por hectárea. Para ambas variables se obtuvieron modelos que predicen menores valores de producción y crecimiento juvenil al intensificarse el régimen de poda, más precisas y con calidades de ajuste levemente mejores que ecuaciones de excelentes comportamientos estadísticos y sin variables vinculadas con las podas. Utilizando las funciones predictivas del área basimétrica se obtuvieron resultados sensibles a las podas respecto del diámetro medio cuadrático. Las funciones obtenidas pueden ser usadas como herramientas de cálculo para decidir cuánto y cuándo podar ramas fotosintéticamente activas de acuerdo a los objetivos de producción. Estos modelos son promisorios para el desarrollo de nuevos programas de simulación de producción y crecimiento regionales de Pinus taeda que contemplen a las podas realizadas en los sistemas de producción intensivos

Isotope effect and bond-stretching phonon anomaly in high-Tc cuprates

We analyse a model where the anomalies of the bond-stretching LO phonon mode are caused by the coupling to electron dynamic response in the form of a damped oscillator and explore the possibility to reconstruct the spectrum of the latter from the phonon measurements. Preliminary estimates point to its location in the mid infrared region and we show how the required additional information can be extracted from the oxygen isotope effect on the phonon spectrum. The model predicts a significant measurable deviation from the "standard value" of the isotope effect even if the phonon frequency is far below the electron spectrum, provided the latter is strongly incoherent. In this regime, which corresponds to the "mid infrared scenario", the phonon linewidth becomes a sensitive and informative probe of the isotope effect.Comment: 10 pages, 2 figures, added reference

Giant phonon anomalies and central peak due to charge density wave formation in YBa2_2Cu3_3O6.6_{6.6}

The electron-phonon interaction is a major factor influencing the competition between collective instabilities in correlated-electron materials, but its role in driving high-temperature superconductivity in the cuprates remains poorly understood. We have used high-resolution inelastic x-ray scattering to monitor low-energy phonons in YBa$_2$Cu$_3$O$_{6.6}$ (superconducting $\bf T_c = 61$ K), which is close to a charge density wave (CDW) instability. Phonons in a narrow range of momentum space around the CDW ordering vector exhibit extremely large superconductivity-induced lineshape renormalizations. These results imply that the electron-phonon interaction has sufficient strength to generate various anomalies in electronic spectra, but does not contribute significantly to Cooper pairing. In addition, a quasi-elastic "central peak" due to CDW nanodomains is observed in a wide temperature range above and below $\bf T_c$, suggesting that the gradual onset of a spatially inhomogeneous CDW domain state with decreasing temperature is a generic feature of the underdoped cuprates