Low strength is related to diminished ground reaction forces and walking performance in older women

The purpose of this study was to determine how lower-limb strength in older women affected gait speed, supportive forces, spatial, and temporal aspects of walking gait. Twenty-four women between 65 – 80 yr performed maximal voluntary isometric contractions for the knee extensors (KE), knee flexors (KF), ankle plantarflexors (PF) and ankle dorsiflexors (DF) and were separated into low strength and normal strength groups using a KE torque threshold of 1.5 Nm kg−1 . They walked at both a standard speed of 0.8 m s−1 and at a self-selected maximal speed on an instrumented treadmill that recorded vertical ground reaction forces (vGRF) and spatiotemporal gait measures. Older women with low strength had 30% lower KE maximal torque, 36% lower PF maximal torque, 34% lower KE rate of torque development (RTD) and 30% lower KF RTD. Low strength women demonstrated slower maximal walking speeds (1.26 ± 0.20 vs. 1.56 ± 0.20 m s−1 ), lower vGRF during weight acceptance (1.15 ± 0.10 vs. 1.27 ± 0.13 BW), lower weight acceptance rates (11.3 ± 0.5 vs. 17.0 ± 5.5 BW s−1 ), slower stride rates, shorter stride lengths, and longer footground and double-limb support times (all P \u3c 0.05). Maximal gait speed was strongly correlated to peak vGRF and rate (r = 0.60 – 0.85, P \u3c 0.01) and moderately related to lower-limb strength (r = 0.42 – 0.60, P \u3c 0.05). In older women with low strength, diminished peak vGRFs were associated with slower walking speeds putting them at risk for mobility limitation, disability, poor health, and loss of independence

Magnetometer measures orthogonal components of magnetic fields

Driven magnetometer accurately measures the components of a low strength magnetic field in each of three mutually perpendicular directions. To accomplish this, it employs the principle of magnetic resonance in optically pumped rubidium vapor

A Passively Mode-locked Nanosecond Laser with an Ultra-narrow Spectral Width

Many different mode-locking techniques have been realized in the past [1, 2], but mainly focused on increasing the spectral bandwidth to achieve ultra-short coherent light pulses with well below picosecond duration. In contrast, no mode-locked laser scheme has managed to generate Fourier-limited nanosecond long pulses, which feature narrow spectral bandwidths (~MHz regime) instrumental to applications in spectroscopy, efficient excitation of molecules, sensing, and quantum optics. The related limitations are mainly caused by the adverse operation timescales of saturable absorbers, as well as by the low strength of the nonlinear effects typically reachable through nanosecond pulses with manageable energies

Anomalous ideal tensile strength of ferromagnetic Fe and Fe-rich alloys

Within the same failure mode, iron has the lowest ideal tensile strength among the transition metals crystallizing in the body-centered cubic structure. Here, we demonstrate that this anomalously low strength of Fe originates partly from magnetism and is reflected in unexpected alloying effects in dilute Fe(\emph{M}) (\emph{M} = Al, V, Cr, Mn, Co, Ni) binaries. We employ the structural energy difference and the magnetic pressure to disentangle the magnetic effect on the ideal tensile strength from the chemical effect. We find that the investigated solutes strongly alter the magnetic response of the Fe host from the weak towards a stronger ferromagnetic behavior, which is explained based on single-particle band energies.Comment: 5 pages, 4 figure

Fuzzy simulation of forest road surface parameters

The problem of construction of forest roads with the use of local low-strength substandard materials and industrial waste is considered. To solve the problem, the primary task is to develop a method for estimating the parameters of road surfaces taking into account the conditions of uncertainties in the data. This technique allows us to reasonably clarify some of the regulatory parameters and improve the technology of construction of forest roads, which was the goal of the work. To formalize the task, experimental studies were performed and on the basis of these results, the statement of the task of fuzzy derivation of the function for estimating the bearing capacity of the coating was performed. The synthesis of the output function is performed by means of Matlab. © 2019 IOP Publishing Ltd. All rights reserved

Properties of the random field Ising model in a transverse magnetic field

We consider the effect of a random longitudinal field on the Ising model in a transverse magnetic field. For spatial dimension $d > 2$, there is at low strength of randomness and transverse field, a phase with true long range order which is destroyed at higher values of the randomness or transverse field. The properties of the quantum phase transition at zero temperature are controlled by a fixed point with no quantum fluctuations. This fixed point also controls the classical finite temperature phase transition in this model. Many critical properties of the quantum transition are therefore identical to those of the classical transition. In particular, we argue that the dynamical scaling is activated, i.e, the logarithm of the diverging time scale rises as a power of the diverging length scale

Experimental evidence for non-proportional growth of large craters

Evidence from laboratory impact experiments is indicating that increasing crater aspect ratios (diameter:depth) can result from increasing both velocity and projectile size without invoking unusual impactor conditions. An extensive data base of experimental impact cratering was analyzed for a variety of impactors and impact velocities for low strength targets. These data indicate a change in cratering efficiency that appears to be related to the onset of projectile deformation or rupture. When all projectile types and sizes are considered, one finds two contrasting relationships between crater aspect ratio and impactor parameter. These relationships are briefly considered

Durability Studies on Native Soil-Based Controlled Low Strength Materials

The Integrated Pipeline Project (IPL) is a collaborative effort between the Tarrant Regional Water District (TRWD) and Dallas Water Utilities (DWU), which bring additional water supplies to the Dallas / Fort Worth area. As part of a sustainability initiative, several studies were conducted to assess the reuse potential of excavated materials along the IPL project. One of these studies involved using the excavated material as an ingredient in Controlled Low Strength Material, often known as CLSM or flowable fill. This flowable fill can be used as bedding and haunch material in pipeline construction. These CLSMs meet the specifications in the short-term; however their long-term performance should be verified in order to be successfully used in the field, especially when these materials are subjected to seasonal changes such as wetting and drying. Hence, durability studies were conducted on CLSMs from two different geologic formations, namely Eagle Ford and Queen City formations. The variations in retained strength and volumetric strain changes, along with the amount of stabilizer leached out of the CLSM samples at different durability cycles, are presented in this paper. It was observed that Eagle Ford soil CLSM lost more than 50% of its initial strength while Queen City sand CLSM lost approximately 50% of its initial strength when subjected to durability studies. The loss in strength was attributed to both volume change and stabilizer loss in case of Eagle Ford soil while stabilizer loss alone caused the loss of strength in the case of Queen City sand

The Effect of Web Usability on Users’ Web Experience

The ease with which a website visitor can find what they need is positively correlated with visitor satisfaction(Institute for Dynamic Educational Advancement, 2008). Web usability is a field that studies what factors affect the visitor’s ability to navigate through a website. Although there are publications outlining specific usability guidelines, many of them have little or no academic research to support the claim. HHS developed a list of 209 guidelines and rated each according to their strength of evidence (research-based support, 5 – high, 1 – low). Using heuristic evaluation and usability testing, this study provides additional research-based knowledge for those guidelines rated with a low strength of evidence. Results indicate that users desire printer-friendly webpages, require feedback on their location within the website, find linking to related content helpful, and expect a search option to be provided on every page. Additional research is necessary to determine if providing descriptive page titles or labeling pushbuttons clearly is important to web usability

Factors affecting measurement of hydraulic conductivity in low strength cementitious materials

The hydraulic conductivity (water permeability) is one of the most significant transport properties of concrete and measuring it is a key step in predicting the performance of concrete as a barrier to the movement of fluids and ions. The transport properties are critical for the performance of the cover layer in protecting embedded reinforcement as waste containments barriers (which are considered in this paper) and other applications such as dams. The measurements are difficult to interpret due to experimental effects of sample size and changes of flow with time and the chemistry of the fluid used. The intrinsic permeability to water and synthetic leachate was determined and the relationship between the eluted volume passing and permeability was established for mortar mixtures having compressive strengths ranging from 5 to 20 MPa. Two mortar mixtures containing portland cement and one without portland cement and incorporating cement kiln dust, lagoon ash, and Ferrosilicate slag were tested. The effects of the sample size were also investigated. The results indicate a decrease in hydraulic conductivity for lower strength mixtures and a slight increase in permeability coefficient for the higher strength mixtures with increasing permeating volumes. Increasing the testing specimen size also slightly increased the coefficient of permeability in lower strength mixtures and decreased the coefficient in higher strength mixtures. The permeability coefficient did not change significantly with pore solution pressure