Outward Direction Research Articles

An effective balancing response to lateral perturbations at pelvis level during slow walking requires control in all three planes of motion

In this study we investigated balancing responses to lateral perturbations during slow walking (0.85m/s). A group of seven healthy individuals walked on an instrumented treadmill while being perturbed at the level of waist at left heel strike in outward and inward lateral directions. Centre of mass (COM) and centre of pressure (COP), rotation of pelvis around vertical axis, step lengths, step widths and step times were assessed. The results have shown that beside control of COP in lateral direction, facilitated by adequate step widths, control of COP in sagittal direction, slowing down movement of COM was present after commencement of lateral perturbations. Sagittal component of COM was significantly retarded as compared to unperturbed walking for both inward (4.32±1.29cm) and outward (9.75±2.17cm) perturbations. This was necessary since after an inward perturbation first step length (0.29±0.04m compared to 0.52±0.02m in unperturbed walking) and step time (0.45±0.05s compared to 0.61±0.04s in unperturbed walking) were shortened while after an outward perturbation first two step lengths (0.36±0.05m and 0.32±0.11m compared to 0.52±0.03m in unperturbed walking) were shortened that needed to be accommodated by the described modulation of COP in sagittal plane. In addition pronounced pelvis rotation assisted in bringing swing leg to new location. The results of this study show that counteracting lateral perturbations at slow walking requires adequate response in all three planes of motion.

Numerical simulation of the hydrodynamics and water exchange in Sansha Bay

A two-dimensional shallow water hydrodynamic finite element model (SHYFEM) was applied to Sansha Bay, Fujian, China. The model was used to investigate the hydrographic characteristics of the bay and in particular its water-exchange ability with the open sea. Comparisons between model output and observations indicate that the model is generally capable of reproducing the variability of water level and currents in the study region. Further analysis suggests that the magnitude of currents is larger in deep water areas such as channels, reaching approximately 1ms−1, whereas it is often less than 0.5ms−1 in shallow water areas such as tidal flats. By contrast, the residual currents are much weaker, without a clear inward or outward direction. Seawater in deeper areas tends to exchange faster with the open sea compared to that in shallower regions. The half-exchange time of sea water is <10 d along main channels, while it exceeds 30 d in bay heads. Model sensitivities suggest that (i) dredging of tidal flats increases the exchange rate of seawater near bay heads, (ii) increasing river runoff or opening up an extra passage can significantly increase the exchange rate locally yet slightly decrease it in other secondary bays.

Glycans in the intestinal peptide transporter PEPT1 contribute to function and protect from proteolysis.

Despite the fact that many membrane proteins carry extracellular glycans, little is known about whether the glycan chains also affect protein function. We recently demonstrated that the proton-coupled oligopeptide transporter 1 (PEPT1) in the intestine is glycosylated at six asparagine residues (N50, N406, N439, N510, N515, and N532). Mutagenesis-induced disruption of the individual N-glycosylation site N50, which is highly conserved among mammals, was detected to significantly enhance the PEPT1-mediated inward transport of peptides. Here, we show that for the murine protein the inhibition of glycosylation at sequon N50 by substituting N50 with glutamine, lysine, or cysteine or by replacing S52 with alanine equally altered PEPT1 transport kinetics in oocytes. Furthermore, we provide evidence that the uptake of [14C]glycyl-sarcosine in immortalized murine small intestinal (MODE-K) or colonic epithelial (PTK-6) cells stably expressing the PEPT1 transporter N50Q is also significantly increased relative to the wild-type protein. By using electrophysiological recordings and tracer flux studies, we further demonstrate that the rise in transport velocity observed for PEPT1 N50Q is bidirectional. In line with these findings, we show that attachment of biotin derivatives, comparable in weight with two to four monosaccharides, to the PEPT1 N50C transporter slows down the transport velocity. In addition, our experiments provide strong evidence that glycosylation of PEPT1 confers resistance against proteolytic cleavage by proteinase K, whereas a remarkable intrinsic stability against trypsin, even in the absence of N-linked glycans, was detected.NEW & NOTEWORTHY This study highlights the role of N50-linked glycans in modulating the bidirectional transport activity of the murine peptide transporter PEPT1. Electrophysiological and tracer flux measurements in Xenopus oocytes have shown that removal of the N50 glycans increases the maximal peptide transport rate in the inward and outward directions. This effect could be largely reversed by replacement of N50 glycans with structurally dissimilar biotin derivatives. In addition, N-glycans were detected to stabilize PEPT1 against proteolytic cleavage.

Leading Edge Jet Impingement Under High Rotation Numbers

The effect of rotation on jet impingement cooling is experimentally investigated in this study. Pressurized cooling air is supplied to a smooth, square channel in the radial outward direction. To model leading edge impingement in a gas turbine, jets are formed from a single row of discrete holes. The cooling air from the first pass is expelled through the holes, with the jets impinging on a semi-circular, concave surface. The inlet Reynolds number varied from 10,000 to 40,000 in the square supply channel. The rotation number and buoyancy parameter varied from 0 to 1.4 and 0 to 6.6 near the inlet of the channel, and as coolant is extracted for jet impingement, the rotation and buoyancy numbers can exceed 10 and 500 near the end of the passage. The average jet Reynolds number varied from 6000 to 24,000, and the jet rotation number varied from 0 to 0.13. For all test cases, the jet-to-jet spacing (s/djet = 4), the jet-to-target surface spacing (l/djet = 3.2), and the impingement surface diameter-to-diameter (D/djet = 6.4) were held constant. A steady-state technique was implemented to determine regionally averaged Nusselt numbers on the leading and trailing surfaces inside the supply channel and three spanwise locations on the concave target surface. It was observed that in all rotating test cases, the Nusselt numbers deviated from those measured in a nonrotating channel. The degree of separation between the leading and trailing surface increased with increasing rotation number. Near the inlet of the channel, heat transfer was dominated by entrance effects, however moving downstream, the local rotation number increased, and the effect of rotation was more pronounced. The effect of rotation on the target surface was most clearly seen in the absence of crossflow. With pure jet impingement, the deflection of the impinging jet combined with the rotation-induced secondary flows offered increased mixing within the impingement cavity and enhanced heat transfer. In the presence of strong crossflow of the spent air, the same level of heat transfer is measured in both the stationary and rotating channels.

Area bound for a surface in a strong gravity region

For asymptotically flat spacetimes, using the inverse mean curvature flow, we show that any compact $2$-surface, $S_0$, whose mean curvature and its derivative for outward direction are positive in spacelike hypersurface with non-negative Ricci scalar satisfies the inequality $A_0 \leq 4 \pi (3Gm)^2$, where $A_0$ is the area of $S_0$ and $m$ is the total mass. The upper bound is realized when $S_0$ is the photon sphere in a hypersurface isometric to $t=$const. slice of the Schwarzschild spacetime.

Healing mechanism of nanocrack in nanocrystalline metals during creep process

Molecular dynamics (MD) simulation has been performed to demonstrate the fate of cracks present inside ultrafine-grained (grain size ~ 7 nm) nanocrystalline Ni specimen during creep deformation process. It is observed that internal nanocracks are healed within a few pico-seconds of initial part of creep process even if the constant applied load on the specimen is tensile in nature and acting normal to crack surface in the outward direction. This kind of crack-healing phenomenon can be accounted by the facts such as stress-driven grain boundary migration, grain boundary diffusion and amorphization of specimen as per results obtained from this MD simulation. This MD study also reveals that the presence of nanocrack inside ultrafine-grained NC Ni in fact slightly improves creep properties and such enhancement of the creep properties is intensified as the size of internal crack increases.

On the Simulation of Floods in a Narrow Bending Valley: The Malpasset Dam Break Case Study

In this paper, we investigate the performance of three-dimensional (3D) hydraulic modeling when dealing with river sinuosity and meander bends. In river bends, the flow is dominated by a secondary current, which has a key role on the flow redistribution. The secondary flow induces transverse components of the bed shear stress and increases the velocity in outward direction, thus generating local erosion and riverbed modifications. When in river bends, the 3D processes prevail, and a 3D computational fluid dynamics (CFD) model is required to correctly predict the flow structure. An accurate description of the different hydrodynamic processes in mildly and sharply curved bends find a relevant application in meanders migration modeling. The mechanisms that drive the velocity redistribution in meandering channels depend on the river’s roughness, the flow depth (H), the radius curvature (R), the width (B) and the bathymetric variations. Here, the hydro-geomorphic characterization of sharp and mild meanders is performed by means of the ratios R/B, B/H, and R/H, and of the sinuosity index. As a case study, we selected the Malpasset dam break on the Reyran River Valley (FR), as it is perfectly suited for investigating performances and issues of a 3D model in simulating the inundation dynamics in a river channel with a varying curvature radius.

Water Budget Analysis within the Surrounding of Prominent Lakes and Reservoirs from Multi-Sensor Earth Observation Data and Hydrological Models: Case Studies of the Aral Sea and Lake Mead

The hydrological budget of a region is determined based on the horizontal and vertical water fluxes acting in both inward and outward directions. These integrated water fluxes vary, altering the total water storage and consequently the gravitational force of the region. The time-dependent gravitational field can be observed through the Gravity Recovery and Climate Experiment (GRACE) gravimetric satellite mission, provided that the mass variation is above the sensitivity of GRACE. This study evaluates mass changes in prominent reservoir regions through three independent approaches viz. fluxes, storages, and gravity, by combining remote sensing products, in-situ data and hydrological model outputs using WaterGAP Global Hydrological Model (WGHM) and Global Land Data Assimilation System (GLDAS). The results show that the dynamics revealed by the GRACE signal can be better explored by a hybrid method, which combines remote sensing-based reservoir volume estimates with hydrological model outputs, than by exclusive model-based storage estimates. For the given arid/semi-arid regions, GLDAS based storage estimations perform better than WGHM.

Physiologic statokinetic dissociation is eliminated by equating static and kinetic perimetry testing procedures.

In the present study, we measured the extent of statokinetic dissociation (SKD) in normal observers and then equated the psychophysical tasks into a two-interval forced choice (2IFC) procedure. In Experiment 1, we used the Humphrey visual field analyzer in static perimetry and automated kinetic perimetry modes to measure contrast sensitivity thresholds and the Goldmann manual kinetic perimeter to measure isopters. This was carried out using a Goldmann size II target. Goldmann kinetic perimetry was performed manually with both inward (peripheral to center) and outward (center to periphery) directions of movement to deduce an "average" isopter. This revealed the presence of SKD when superimposed upon the map of static contrast threshold results. There was no evidence of any contribution of examiner technique or instrument-specific differences to SKD. In Experiment 2, we determined the psychometric curves plotting proportion seen as a function of stimulus eccentricity with static and kinetic stimuli with a 2IFC procedure and method of constant stimuli. In an additional experiment, we also showed that subjects were able to reliably discriminate whether a stimulus was static, moving inward, or moving outward, and hence, comparisons could be made between static and kinetic perimetry tasks. Overall, by making the task objective and reducing criterion bias, eccentricity thresholds were equated across static and kinetic perimetry methods; hence, no evidence of SKD was seen. We suggest SKD is inherent to the differences in methodology of threshold measurement in conventional static and kinetic perimetry and individual criterion bias.

Feasibility Design Study of Long Life BWR with Natural Uranium/Thorium as Fuel Cycle Input

Feasibility design study of Long Life BWR with natural uranium/thorium as fuel cycle input has been performed. The reactor core is divided into 6 equal regions in radial direction. The fresh fuel is first loaded into the most outer region then shifted to the center of the core, and from there shifted to the nearby region in the outward direction. Nitride fuel is employed in the core to get better criticality and conversion/breeding ratio. The results show that uranium fuel combined with low moderating ratio environment is superior to make the system critical.

Mathematical assessment of drug build-up in the posterior eye following transscleral delivery

Delivery of drugs to the posterior segment of the eye is a significant challenge in the field of opthalmic pharmaceuticals. Several restrictive barriers hinder drug delivery to this district. Static barriers include tissues and limiting membranes, while dynamic barriers include drug clearance mechanism from blood and lymphatics. Strategies for delivering drugs to the posterior segment most often consist in topical ocular medications or systemic administrations, but dose/response profiles are generally very poor. Intravitreal injections and transscleral delivery are new emerging techniques with promising results. Purpose of this study is to develop a mathematical model to assess drug levels subsequent to a transscleral drug implant. Both computational and analytical techniques are adopted. The model comprises sclera, choroid, retina and vitreous along with the retina pigment epithelium at the choroid-retina boundary and the inner blood retinal barrier of the retinal vessels. Darcy equations are used to compute the filtration velocity of the interstitial fluid and a fictitious velocity field is added to model active pumping from the retinal pigmented epithelium. Convective-diffusive-reactive equations for drug concentration are then solved. Permeability parameters and partition coefficients simulate the presence of internal membranes and barriers, with possible different values in outward and inward directions. An important result of the model is the evaluation of the roles of the different physical parameters, which offers key points to improve drug delivery techniques. Namely, the sensitivity study suggests that diffusion in tissue, clearance rates, membrane permeabilities and active pumping play important roles in determining drug peak concentration and time-to-peak. However, their relative influence can be dramatically different depending on the rate-limiting parameter.

Collective pulsatile expansion and swirls in proliferating tumor tissue

Understanding the dynamics of expanding biological tissues is essential to a wide range of phenomena in morphogenesis, wound healing and tumor proliferation. Increasing evidence suggests that many of the relevant phenomena originate from complex collective dynamics, inherently nonlinear, of constituent cells that are physically active. Here, we investigate thin disk layers of proliferating, cohesive, monoclonal tumor cells and report the discovery of macroscopic, periodic, soliton-like mechanical waves with which cells are collectively ratcheting, as in the traveling-wave chemotaxis of dictyostelium discodium amoeba cells. The relevant length-scale of the waves is remarkably large (∼1 mm), compared to the thickness of a mono-layer tissue (). During the tissue expansion, the waves are found to repeat several times with a quite well defined period of approximately 4 h. Our analyses suggest that the waves are initiated by the leading edge that actively pulls the tissue in the outward direction, while the cells within the bulk tissue do not seem to generate a strong self-propulsion. Subsequently, we demonstrate that a simple mathematical model chain of nonlinear springs that are constantly pulled in the outward direction at the leading edge recapitulates the observed phenomena well. As the areal cell density becomes too high, the tissue expansion stalls and the periodic traveling waves yield to multiple swirling vortices. Cancer cells are known to possess a broad spectrum of migration mechanisms. Yet, our finding has established a new unusual mode of tumor tissue expansion, and it may be equally applicable for many different expanding thin layers of cell tissues.

Maximum efficiency of the collisional Penrose process

We consider collision of two particles that move in the equatorial plane near a general stationary rotating axially symmetric extremal black hole. One of particles is critical (with fine-tuned parameters) and moves in the outward direction. The second particle (usual, not fine-tuned) comes from infinity. We examine the efficiency $\eta $ of the collisional Penrose process. There are two relevant cases here: (i) a particle falling into a black hole after collision is heavy, (ii) it has a finite mass. We show that the maximum of $\eta $ in case (ii) is less or equal to that in case (i). It is argued that for superheavy particles, the bound applies to nonequatorial motion as well. As an example, we analyze collision in the Kerr-Newman background. When the bound is the same for processes (i) and (ii), $\eta =3$ for this metric. For the Kerr black hole, recent results in literature are reproduced.

Internal Stresses in PVD Coated Tool Composites

AbstractThe aim of work is the investigation of the internal stresses in PVD coated metal matrix composites (MMC). Sintered MMC substrate is composed of the matrix with the chemical composition corresponding to the high-speed steel, reinforced with the TiC type hard carbide phase. Functionally graded composition of MMC providing of high ductility characteristic of steel in the core zone as well as high hardness characteristic of cemented carbides in the surface zone. Internal stresses were determined with use of finite element method in ANSYS environment. The reason of undertaking the work is necessity of develop the research of internal stresses, occurring in the coating, as well as in the adhesion zone of coating and substrate, which makes it possible to draw valuable conclusions concerning engineering process of the advisable structure and chemical composition of coatings. The investigations were carried out on cutting tool’s models containing defined zones differing in chemical composition.Modelled materials were characteristic of chemical composition corresponding to the high-speed steel at the core, reinforced with the TiC type hard carbide phase with the growing fraction of these phases in the outward direction from the core to the surface, additionally coated with (Ti,Al)N or Ti(C,N) functionally graded PVD coatings.Results of determined internal stresses were compared with the results calculated using experimental X-ray sin2ψ method. It was demonstrated, that the presented model meets the initial criteria, which gives ground to the assumption about its utility for determining the stresses in coatings as well as in functionally graded sintered materials. The results of computer simulations correlate with the experimental results.

On a nonlinear problem with zero Dirichlet boundary condition

We are concerned with the following PDE: , in , , on , where is a bounded domain of , and is a given function. We provide a complete description of the loss of compactness of the equation under the assumption that K is strictly decreasing in the outward normal direction on and flat near its critical points. As product, we prove an existence result through an Euler–Poincaré characteristic argument.

Complex Metal–Organic Frameworks from Symmetrically Backfolded Dendrimers

AbstractWe study symmetrically backfolded building blocks (Sierpinski dendrimers) that generate metal‐organic frameworks featuring graphitic ribbons, free‐standing carboxylic functions and intricate topologies in clear correspondence with molecular structures. Unlike the starburst shape of traditional dendrimers, the Sierpinski dendrimer features side branches bent away (e. g., by 120°) from the outward direction of the main branch. This paper reports a systematic attempt to correlate the backfolded shape with the connectivity (topology) of the resultant network. Our discovery is surprisingly simple: as building blocks for extended nets, the backfolded Sierpinski dendrimer behaves as a collection of subsidiary building units of the conventional starburst shape (e. g., the regular tritopic unit); and the resultant networks can be deconstructed into subnets corresponding to the star‐shaped subunits of the molecule. These seemingly exotic and highly branched molecules are not only compatible with the purpose of network construction, but also present fundamentally new features that open new horizons for molecular design.

Instability of visual error processing for sensorimotor adaptation in schizophrenia.

Saccadic adaptation can be used to study disturbances of sensory processing and motor learning. We investigated whether patients with schizophrenia can adjust saccadic amplitudes to account for an increase in visual error while the saccade is in flight, and whether they transfer this change to a visuo-manual localization task. Fourteen patients (mean 37.1years) and 14 healthy controls (mean 35.1years) performed 200 adaptation trials of 10° with target shifts of 4° in the outward direction. We determined the percent amplitude change during adaptation and adaptation speed. In addition, subjects localized a stimulus that was flashed 50ms after saccade target onset to measure the transfer of change in visual space perception to visuo-manual coordination. Eye movements were recorded at 1000Hz. Saccade amplitudes increased over adaptation trials by 11% (p<0.001) similarly in both groups. Amplitude variability during adaptation was higher in patients (1.06°±0.32°) than in controls (0.71°±0.14°; p=0.001), while adaptation speed was slower in patients (0.02±0.03) than in controls (0.11±0.11; p=0.01). Other pre- and post-adaptation saccade metrics did not differ between groups. The adaptation process shifted localization of the flashed target in the adaptation direction similarly in both groups. The use of error signals for the internal recalibration of sensorimotor systems and the transfer of this recalibration to visual space perception appear basically unimpaired in schizophrenia. Higher amplitude variability in patients suggests a certain instability of saccadic control in cerebellar systems. Patients seem to rely on visual error processing in frontal circuitry, resulting in slower adaptation speeds, despite unimpaired adaptation strength.

Helium transport in the core and stochastic edge layer in LHD

Radial profiles of the density ratio of helium to hydrogen ions are measured using charge exchange spectroscopy with a two-wavelength spectrometer in the large helical device. Helium transport at the last closed flux surface (LCFS) and stochastic magnetic field layer outside the LCFS as well as in the core plasma is studied for a wide range of helium fractions, i.e. from hydrogen-dominated plasmas up to helium-dominated plasmas. The helium density profile becomes more peaked and inward convection velocity increases in the hydrogen-dominant plasma, while it becomes flat or hollow and the convection velocity is in the outward direction in the helium-dominant plasmas. The density gradient of helium at the LCFS is twice that of hydrogen and becomes steeper as the hydrogen becomes more dominant.

Surface charge-induced EDL interaction on the contact angle of surface nanobubbles.

The contact angle (CA) of surface nanobubbles is believed to affect the stability of nanobubbles and fluid drag in micro/nanofluidic systems. The CA of nanobubbles is dependent on size and is believed to be affected by the surface charge-induced electrical double layer (EDL). However, neither of these of attributes are well understood. In this paper, by introducing an EDL-induced electrostatic wetting tension, a theoretical model is first established to study the effect of EDLs formed near the solid-liquid interface and the liquid-nanobubble interface on the gas phase CA of nanobubbles. The size-dependence of this EDL interaction is studied as well. Next, by using atomic force microscopy (AFM), the effect of the EDL on nanobubbles' gas phase CA is studied with variable electrical potential at the solid-liquid interface, which is adjusted by an applied voltage. Both the theoretical and the experimental results show that the EDLs formed near the solid-liquid interface and the liquid-nanobubble interface lead to a reduction of gas phase CA of the surface nanobubbles because of an electrostatic wetting tension on the nanobubble due to the attractive electrostatic interaction between the liquid and nanobubble within the EDL, which is in the nanobubbles' outward direction. An EDL with a larger zeta potential magnitude leads to a larger gas phase CA reduction. Furthermore, the effect of EDL on the nanobubbles' gas phase CA shows a significant size-dependence considering the size dependence of the electrostatic wetting tension. The gas phase CA reduction due to the EDL decreases with increasing nanobubble height and increases with the nanobubble's increasing curvature radius, indicating that a surface charge-induced EDL could possibly explain the size dependence of the gas phase CA of nanobubbles.

Action of the diaphragm on the rib cage.

When the diaphragm contracts, pleural pressure falls, exerting a caudal and inward force on the entire rib cage. However, the diaphragm also exerts forces in the cranial and outward direction on the lower ribs. One of these forces, the "insertional force," is applied by the muscle at its attachments to the lower ribs. The second, the "appositional force," is due to the transmission of abdominal pressure to the lower rib cage in the zone of apposition. In the control condition at functional residual capacity, the effects of these two forces on the lower ribs are nearly equal and outweigh the effect of pleural pressure, whereas for the upper ribs, the effect of pleural pressure is greater. The balance between these effects, however, may be altered. When the abdomen is given a mechanical support, the insertional and appositional forces are increased, so that the muscle produces a larger expansion of the lower rib cage and, with it, a smaller retraction of the upper rib cage. In contrast, at higher lung volumes the zone of apposition is decreased, and pleural pressure is the dominant force on the lower ribs as well. Consequently, although the force exerted by the diaphragm on these ribs remains inspiratory, rib displacement is reversed into a caudal-inward displacement. This mechanism likely explains the inspiratory retraction of the lateral walls of the lower rib cage observed in many subjects with chronic obstructive pulmonary disease (Hoover's sign). These observations support the use of a three-compartment, rather than a two-compartment, model to describe chest wall mechanics.