Critical state parameters for a saturated lateritic clay

The critical state soil mechanics is the most useful framework for understanding responses of different soil type to mechanical stress. For lateritic soil, widely distributed soil in the tropics and well recognized for its rich composition in oxides of iron and aluminum (sesqui-oxide), its mechanical behaviour has not been well studied within this framework. Therefore, a good understanding of the compressibility and shear strength properties of the lateritic soil would improve the designs of structures built on it. This paper presents experimental data from isotropic compression and consolidated undrained triaxial tests on saturated samples of lateritic soil from Nigeria. The data from these tests are presented and interpreted within the critical-state framework. Effects of sesquioxide composition on the compressibility and dilatancy is re-ported and discussed

Reliability of HCT-based Soil Water Retention Curves

The measurement of SWRCs using HCTs has been the subject of several recent studies. Consequently, there have been several design and experimental procedures developed. However, despite these developments, the accuracy, range and duration of HCT-based measurement is still largely characterized by uncertainties and inconsistencies, thereby, reducing the reliability of the obtained SWRCs. In this work, an experimental program is designed to address these uncertainties. SWRCs of reconstituted London clay were measured using the continuous drying method with evaporation rate control. The obtained SWRCs were analysed based on the maximum suction value recorded by HCTs (sₘₐₓ), the obtained air-entry value (sₐₑᵥ), the suction at inflection point (sᵢ), the water content at inflection point (wᵢ), and the slope of tangent to inflection point (mᵢ). A percentage uncertainty of ±4% was obtained for the saev and si values. Similarly, percentage uncertainties of ±6% and ±0.5% were obtained respectively for the mᵢ and wᵢ values. These results were further compared with parametric analysis of the reported SWRCs of the same soil in the literature. Given the observed tolerance ranges, cautions must be taken in selecting values for these parameters e.g. as input values in mathematical curve fitting equations for prediction of the entire SWRC, or in unsaturated constitutive modelling, to enhance reliability of the outputs

Neutron spectroscopic study of crystal field excitations in Tb2Ti2O7 and Tb2Sn2O7

We present time-of-flight inelastic neutron scattering measurements at low temperature on powder samples of the magnetic pyrochlore oxides Tb2Ti2O7 and Tb2Sn2O7. These two materials possess related, but different ground states, with Tb2Sn2O7 displaying "soft" spin ice order below Tn~0.87 K, while Tb2Ti2O7 enters a hybrid, glassy spin ice state below Tg~0.2 K. Our neutron measurements, performed at T=1.5 K and 30 K, probe the crystal field states associated with the J=6 states of Tb3+ within the appropriate Fd\bar{3}m pyrochlore environment. These crystal field states determine the size and anisotropy of the Tb3+ magnetic moment in each material's ground state, information that is an essential starting point for any description of the low-temperature phase behavior and spin dynamics in Tb2Ti2O7 and Tb2Sn2O7. While these two materials have much in common, the cubic stanate lattice is expanded compared to the cubic titanate lattice. As our measurements show, this translates into a factor of ~2 increase in the crystal field bandwidth of the 2J+1=13 states in Tb2Ti2O7 compared with Tb2Sn2O7. Our results are consistent with previous measurements on crystal field states in Tb2Sn2O7, wherein the ground state doublet corresponds primarily to m_J=|\pm 5> and the first excited state doublet to mJ=|\pm 4>. In contrast, our results on Tb2Ti2O7 differ markedly from earlier studies, showing that the ground state doublet corresponds to a significant mixture of mJ=|\pm 5>, |\mp 4>, and |\pm 2>, while the first excited state doublet corresponds to a mixture of mJ=|\pm 4>, |\mp 5>, and |\pm 1>. We discuss these results in the context of proposed mechanisms for the failure of Tb2Ti2O7 to develop conventional long-range order down to 50 mK.Comment: 12 pages, 6 figures. Version is the same as the published one, except for figure placement on page

Effects of an Exercise-Oriented Rehabilitation Program on Mechanical Efficiency and Aerobic Capacity in Children with Spastic Cerebral Palsy

AbstractObjectiveChildren suffering from Cerebral Palsy (CP), exhibit movement limitations and physiological abnormalities as compared to normal individuals.The objective of this study was to assess mechanical efficiency and certain cardiovascular indices before and after an exercise-rehabilitation program in children with dipelegia spastic cerebral palsy (experimental group) in comparison with able-bodied children(controls). Material and MethodsIn this study, 15 spastic cerebral palsy (dipelegic) children participated in an exercise-rehabilitation program, three days a week for three months with an average 144bpm of heart rate. The mechanical efficiency (net, gross), rest and submaximal heart rate and maximal oxygen consumption (VO2max) were measured before (pretest) and after (posttest) exercise program on the cycle ergometer according to the Macmaster ergometer protocol. Then control group, of 18 normal children underwent the exercise program and were assessed, following which results of the 2 groups were compared using SPSS for statistical analysis (P<0.05). ResultsMechanical efficiency (net, gross) increased significantly in CP patients after the exercise-rehabilitation program; reults did not alter significantly for the controls.Rest and submaximal heart rate in CP patients decreased significantly after exercise program. Maximal oxygen consumption, which remained unchanged in patients following the exercise program, was similar in patients and controls after the program. ConclusionCerebral palsy patients, because of their high muscle tone, severe degree of spasticity, and involuntary movements are physically more incapacitated and need more energy than normal able-bodied individuals. Rehabilitation and aerobic exercise can be effective in improving their cardiovascular fitness and muscle function and increasing their mechanical efficiency

A new method for venom extraction from venomous fish, green scat

Scatophagus argus argus (Green Scat) is a pretty aquarium fish. Its hard spines are venomous and can cause painful injury. In this study 60 specimens of Green Scat were collected periodically from coastal waters of Boushehr (south of Iran) from May 2011 to April 2012. Anatomical features of venomous spines were investigated. Scat venom was extracted from the spines in a new manner for keeping the specimens alive. The nature of venom was tested by SDS-PAGE. Ethical issues and animal welfare principles such as rapid and instantaneous anesthetizing, post operation disinfection and fast recovery of the specimens was practiced in order to minimize the complications. This method enhanced the purity and quantity of venom as demonstrated by 12 separated proteins in electrophoresis. New ethical issues were developed to surviving the specimens and prolong viability as well

Effects of Icelandic yogurt consumption and resistance training in healthy untrained older males

Due to the important roles of resistance training and protein consumption in the prevention and treatment of sarcopenia, we assessed the efficacy of post-exercise Icelandic yogurt consumption on lean mass, strength, and skeletal muscle regulatory factors in healthy untrained older males. Thirty healthy untrained older males (age = 68 ± 4 yr) were randomly assigned to Icelandic yogurt (IR; n =15, 18 g of protein) or an iso-energetic placebo (PR; n =15, 0 g protein) immediately following resistance training (3x/week) for eight weeks. Before and after training, lean mass, strength, and skeletal muscle regulatory factors (insulin-like growth factor-1 [IGF-1], transforming growth factor-beta 1 [TGF-β1], growth differentiation factor 15 [GDF15], Activin A, myostatin [MST], and follistatin [FST]) were assessed. There were group x time interactions (p < 0.05) for body mass (IR: Δ 1, PR: Δ 0.7 kg), body mass index (IR: Δ 0.3, PR: Δ 0.2 kg∙m-2), lean mass (IR: Δ 1.3, PR: Δ 0.6 kg), bench press (IR: Δ 4, PR: 2.3 kg), leg press (IR: Δ 4.2, PR: Δ 2.5 kg), IGF-1 (IR: Δ 0.5, Δ PR: 0.1 ng∙mL-1), TGF-β (IR: Δ -0.2, PR: Δ -0.1 ng∙mL-1), GDF15 (IR: Δ -10.3, PR: Δ -4.8 pg∙mL-1), Activin A (IR: Δ -9.8, PR: Δ -2.9 pg∙mL-1), MST (IR: Δ -0.1, PR: Δ -0.04 ng∙mL-1), and FST (IR: Δ 0.09, PR: Δ 0.03 ng∙mL-1), with Icelandic yogurt consumption resulting in greater changes compared to placebo. The addition of Icelandic yogurt consumption to a resistance training program improved lean mass, strength, and altered skeletal muscle regulatory factors in healthy untrained older males compared to placebo. Therefore, Icelandic yogurt as a nutrient-dense source and cost-effective supplement enhances muscular gains mediated by resistance training and consequently may be used as a strategy for the prevention of sarcopenia

Dynamics of threads and polymers in turbulence: power-law distributions and synchronization

We study the behavior of threads and polymers in a turbulent flow. These objects have finite spatial extension, so the flow along them differs slightly. The corresponding drag forces produce a finite average stretching and the thread is stretched most of the time. Nevertheless, the probability of shrinking fluctuations is significant and is known to decay only as a power-law. We show that the exponent of the power law is a universal number independent of the statistics of the flow. For polymers the coil-stretch transition exists: the flow must have a sufficiently large Lyapunov exponent to overcome the elastic resistance and stretch the polymer from the coiled state it takes otherwise. The probability of shrinking from the stretched state above the transition again obeys a power law but with a non-universal exponent. We show that well above the transition the exponent becomes universal and derive the corresponding expression. Furthermore, we demonstrate synchronization: the end-to-end distances of threads or polymers above the transition are synchronized by the flow and become identical. Thus, the transition from Newtonian to non-Newtonian behavior in dilute polymer solutions can be seen as an ordering transition.Comment: 13 pages, version accepted to Journal of Statistical Mechanic