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Effect of strength-to-weight ratio on the time taken to perform a sled-towing exercise

Effect of strength-to-weight ratio on the time taken to perform a sled-towing exercise

Most towing sleds are designed to slide along the ground on runners or a flat base, and have a post on which to stack weights. A cord connects the sled to the athlete via a waist harness or shoulder harness. In a typical sled-towing exercise the athlete starts from a crouched or standing position and then sprints with maximum effort over a short distance (10–50 m). The coach will often record the time taken for the athlete to cover a set distance, and the increase in the athlete’s time relative to the time in unloaded sprinting is an indicator of the intensity of the exercise (Linthorne, 2013; Linthorne & Cooper, 2013; Martínez-Valencia et al., 2013). Knowledge of the intensity of the exercise is very useful to the coach as it is the intensity that determines the training stimulus experienced by the athlete. Unfortunately, setting of the sled weight so that the athlete achieves the desired increase in time is not straight-forward. The time taken by the athlete depends not only on the weight of the sled, but also on the coefficient of friction of the running surface, the athlete’s body mass, and the athlete’s physiological capacities (e.g., lower body power) (Cronin et al., 2008; Linthorne, 2013; Linthorne & Cooper, 2013; Martínez-Valencia et al., 2013; Maulder et al., 2008; Murray et al. 2005). Experimental studies and modelling studies have shown that the time an athlete takes to tow a weighted sled over a given distance increases linearly with increasing sled weight and coefficient of friction (Linthorne, 2013; Linthorne & Cooper, 2013; Martínez-Valencia et al., 2013; Murray et al. 2005). The weight of the sled needs to be increased in proportion to the athlete’s body weight so as to account for the fact that larger athletes tend to generate greater muscular power. Also, athletes with a greater power-to-weight ratio need to be set a greater relative sled weight in order to experience the same exercise intensity because the time taken to tow a weighted sled over a given distance decreases exponentially with increasing power-to-weight ratio (Linthorne, 2013).

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Improving power to weight ratio of pneumatically powered legged robots

Improving power to weight ratio of pneumatically powered legged robots

Legged Robots require actuators with a high power to weight ratio. Although pneumatic actuators do not perform well in this regard, they have other attractive characteristics which are useful in Legged Robots. This paper describes a mechanical solution for significantly improving the payload capacity of a robot powered with pneumatic cylinders, Robug IV, and reports on the theoretical design and experimental outcomes. Keywords: Pneumatic cylinders, legged robots.

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Development of High Strength to Weight Ratio Aluminium – Magnesium Alloy with Enhanced Corrosion Resistance

Development of High Strength to Weight Ratio Aluminium – Magnesium Alloy with Enhanced Corrosion Resistance

In pure state, aluminium has low strength. So it cannot be used in the application where resistance to deformation and fracture is required. Strength can be improved by adding alloying elements to aluminium [1]. The low density combined with high strength has made aluminium alloys attractive in applications where strength- to-weight ratio is a major design consideration. The strength and durability of aluminium alloys vary widely according to the specific alloying, heat treatments and manufacturing processes [1]. Aluminium is mainly used in alloyed form, which results in increasing its mechanical properties. It is used in pure metal form only when corrosion resistance or workability is more important than strength or hardness. A lack of knowledge of these aspects results in improper designed structures and bad reputation to aluminium. The typical alloying elements are copper, magnesium, manganese, silicon and zinc [1].

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Development of High Strength to Weight Ratio Aluminium – Magnesium Alloy with Enhanced Corrosion Resistance

Development of High Strength to Weight Ratio Aluminium – Magnesium Alloy with Enhanced Corrosion Resistance

In pure state, aluminium has low strength. So it cannot be used in the application where resistance to deformation and fracture is required. Strength can be improved by adding alloying elements to aluminium [1]. The low density combined with high strength has made aluminium alloys attractive in applications where strength- to-weight ratio is a major design consideration. The strength and durability of aluminium alloys vary widely according to the specific alloying, heat treatments and manufacturing processes [1]. Aluminium is mainly used in alloyed form, which results in increasing its mechanical properties. It is used in pure metal form only when corrosion resistance or workability is more important than strength or hardness. A lack of knowledge of these aspects results in improper designed structures and bad reputation to aluminium. The typical alloying elements are copper, magnesium, manganese, silicon and zinc [1].

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Population-Based Placental Weight Ratio Distributions and Determinants of Placental Weight Ratios

Population-Based Placental Weight Ratio Distributions and Determinants of Placental Weight Ratios

development, and fetal origins of adult disease. 9–14 While percentile curves for birth weight are available for a variety of jurisdictions and populations, percentile curves for the PWR are not. Thompson et al. 15 created birth weight to placental weight ratio curves using the Norwegian Birth Registry with all singleton live births in Norway from January 1999 to December 2002 (n= 198, 971). These curves were a significant contribution to the literature. Further, no population curves to date have looked at the differences between SGA and LGA across gestational age. Searching the available literature, we found only one other set of PWR percentile curves in a Canadian population. 6 However, the sample size was small (n=20,309). Also, previous studies that have looked at atypical PWRs have not used a population standard to identify abnormal PWRs. 16–18

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Effect of Fiber Weight Ratio and Fiber Modification on Flexural Properties of Posidonia Polyester Composites

Effect of Fiber Weight Ratio and Fiber Modification on Flexural Properties of Posidonia Polyester Composites

The main objective of this research is to study the effect of fiber weight ratio and chemical fiber modification on flexural properties of composites reinforced with Posidonia fiber. An unsaturated polyester matrix reinforced with untreated and treated Posidonia fibers was fabricated under various fiber weight ratios. Results showed that the combined chemical treatment provided better mechanical properties of composites in comparison with untreated fiber. The fiber weight ratio influenced the flexural properties of composites. Indeed, a maximum value of flexural modulus was observed for 10% fiber weight ratio for composites reinforced with treated fibers. SEM pho- tographs revealed a different fracture surface between Posidonia fibers reinforced polyester composites.

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Placement Training Framework Development for MBA

Placement Training Framework Development for MBA

The assessment of changes in physical parameters of biological tissues is an important way in the study of toxicity of heavy metals. It is the study which evaluate toxic effects of mercuric chloride in terms of body weight , liver weight and liver weight /body weight ratio in albino rats after acute and sub-acute treatment of it. For experiment the rats were grouped into 4 sets; one acute & 3 sub-acute (7, 14 and 21 days) and each set considered 4 rats . Control sets were runs simultaneously with each treated set. Body weight show very highly significant decrease in prior two treatments whereas liver weight show highly significant decline through the experiment. Ratio of liver weight /body weight decrease highly significant during prior 3 treatments and very highly significant in last treatment . Mercuric chloride is a systemic poison and whole animal get affected even very minute intake of it.

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Properties of Fiberboards Bonded by Decomposed Polyurethane Foams and Isocyanate

Properties of Fiberboards Bonded by Decomposed Polyurethane Foams and Isocyanate

In this study, PU foams from disposed insulation materials were collected and chemically decomposed to obtain the recycled polyol. The recycled polyol was mixed with commercial polyol at various weight ratios (0: 100, 20: 80, 40: 60, 60: 40, 80: 20, and 100: 0) to prepare polyol mixtures. The obtained polyol mixtures were then sprayed with pMDI resin at various pMDI/polyol mixtures weight ratios (100: 0, 75: 25, and 50: 50) onto wood fibers to prepare fiberboards. The effects of recycled polyol/commercial polyol weight ratio and pMDI/polyol mixture weight ratio on physical and mechanical properties of bonded fiberboards were evaluated. The results showed that the addition of recycled polyol into commercial polyol improved the IB, MOR, and MOE strength of fiberboard, but their effects on water resistance of fiberboard were minor. When the recycled polyol/commercial polyol weight ratio was 40: 60 and the pMDI/polyol mixture was 25: 75, fiberboard had the overall best physical and mechanical performance.

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The effects of pomegranate extract on normal adult rat kidney: A stereological study

The effects of pomegranate extract on normal adult rat kidney: A stereological study

rats were euthanized and their kidneys were removed and processed for morphometric analyses. In rats received pomegranate extract, the kidney weight, kidney weight/body weight ratio, cortex volume and glomerular volume were increased (p < 0.05), while, medulla volume and the number of glomeruli per kidney did not change. No pathological lesions were observed in the kidney. Therefore, pomegranate hydro-alcoholic extract at doses of 250 and 500 (mg kg -1 )

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A neutral-point diode-clamped converter with inherent voltage-boosting for a four-phase SRM drive

A neutral-point diode-clamped converter with inherent voltage-boosting for a four-phase SRM drive

inability to force sufficient current into (or from) the machine at higher speeds (power = torque x speed). DC rail voltage boost (140%) increases the speed at which FLT can be delivered (from 420rpm to 750rpm), hence improving the power to weight ratio (by 75%) to be better than that of a PMSM, for a given source voltage. The NPC converter approach allows series connection of fast low-voltage (600/650V) switches. Hence a device switching frequency well in excess of 20kHz is possible. With alternating zero-volt loops, the load switching frequency is doubled to in excess of 40 kHz, hence minimizing current ripple below base speed and the switching frequency noise is above human audible levels. Below base speed, commutation current profiling can be used to minimize rotational torque ripple between commutating poles hence minimize mechanical audible noise (at multiples of the rotational speed). Radial torque (resonance) ripple (chirp noise at multiples of the rotational speed), due air gap asymmetry and stator compression, at phase commutation is reduced by the necessity of the half voltage (and zero voltage) state during voltage transitions, judiciously synchronized to produce a cancelling counter resonance (being mechanical, the excited frequency is independent of rotor speed).

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THE RATIO OF THE WEIGHT OF SCHOOLBAG TO BODY WEIGHT OF STUDENTS IN AHVAZ CITY

THE RATIO OF THE WEIGHT OF SCHOOLBAG TO BODY WEIGHT OF STUDENTS IN AHVAZ CITY

In several studies [3, 5, and 11] the weight of the girls’ bag was higher than the weight of the boys’ bag that its cause in Ahvaz is this gender’s tendency to have larger and heavier bags, The use of wheeled bags more than boy students, their tendency to use the large 1-1.5 liter bottles of water, carrying more food, more use of non-essential goods and educational books. The Ontario Chiropractic Association in Canada defined students’ bag weight ratio equal to 10% of their body weight. [4] In this study, despite the average proportion was not very high (12% of girls and 11% in boys), but 60 percent of the students had bag weight higher than 10% of body weight that was much higher than in the previous studies that could be due to the more use of wheeled bags as well as the use of mineral water bottles with a weight of one liter and carrying the tuition books for each lesson by Ahvazian students. In this context it is the emphasized that the training managers and staff must take actions for preparing and installing the proper water treatment device in the elementary schools and for stopping the unnecessary use of educational books in the classroom and hence the weight of the students ' bags, and for solving the physical problems caused by the heavy bags.

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Effects Of Dietary Inclusion Of Fish Oil On Broiler Performance And Feed Utilization

Effects Of Dietary Inclusion Of Fish Oil On Broiler Performance And Feed Utilization

of relative water was not significantly affected; during the three weeks. [20], reported that levels of (2 and4 %) fish oil inclusion in diets of broiler decreased weight gain. These results are similar to the results of the current study. [10], observed that the feeding of diet containing fish oil to broilers caused lower body weight than the control diets, those authors attributed the reduced performance levels to lower palatability and higher calcium levels. [17], reported that adding 3% fish oil increased and improved the body weight. The result of body weight in this study showed highly significant difference (P<0.01), It improve body weight because fish oil contain omega-3 fatty acids (EPA and DHA) and good sources of energy. This result agree with the results of [20] but disagree with [10]. The results of feed conversion ratio of broiler fed fish oil were significantly high (P<0.01), these results are similar to [17], who reported that the adding of 3% fish oil; improved feed conversion ratio. [20], reported that adding fish oil levels (2, 4 %) did not affect feed conversion ratio while [1], reported that adding fish oil levels (2, 4 %) improved feed conversion ratio. The results of carcass weight of broiler fed fish oil were highly significant (P<0.01), the result showed that the fish oil improved and increased carcass weight which might be due to the content of fish oil which contain n-3 and n-6, birds fed fish

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Production of Lignin-Based Phenolic Resins Using De-Polymerized Kraft Lignin and Process Optimization

Production of Lignin-Based Phenolic Resins Using De-Polymerized Kraft Lignin and Process Optimization

While lignin hydrolysis demonstrated to be effective for decreasing the Mw of Kraft lignin and increasing the content of hydroxyl phenols (El Masouri et al., 2006; Mahmood et al., 2013), there has been limited research work on applications of the DLs in the synthesis of LPF. Thus, one objective of this chapter is to de-polymerize KL into three different molecular weight ranges using different hydrolysis reaction severities (by varying temperatures and residence time). The other objective of this work is to synthesize LPF resins using the DL products of various Mw obtained from hydrolytic depolymerization of KL, and characterize its physical properties (non volatile content and viscosities) of the resultant LPF resins. For adhesives for engineered wood manufacture applications, the most important physical properties are characterized by nonvolatile content of around 40-45% as well as viscosity in the range of 150-600 cP at 25 o

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Studies on the growth rate of silkworm bombyxmori (l )(lepidoptera: bomycidae) fed with control and natural dye treated mr2 mulberry leaves in relation to silk production

Studies on the growth rate of silkworm bombyxmori (l )(lepidoptera: bomycidae) fed with control and natural dye treated mr2 mulberry leaves in relation to silk production

Kl-karkasy and Idriss, 1990). Since most of this multi-vitamin a compound is consists of ascorbic acid, it could be thought that the increase of larval weight is due to an enhancement of feeding activity. Therefore, natural dye can improve the food digestibility and increase the larval, cocoon and pupal parameters. The enrichment of mulberry leaves with natural dye increase larval and cocoon length, width and weight increase in these insects was related to metabolism other than proteins. It is assumed that fortification of diet supports the metabolism of carbohydrates and lipids, in conclusion, natural dye could increase some biological characteristics in silkworm, but this enhancement could economically improve the Sericulture goals. Natural dyes of which are less toxic, less polluting, less health hazards, non-carcinogenic and non- poisonous. Added to this, they are harmonizing colours, gentle, soft and subtle, and create a restful effect. Above all, they are environment friendly and can be recycled after use. In the present study, the treatment of natural dye at the concentration of 1 gram indigo natural dye may have beneficial effects on the growth of the silkworm larval and pupal width and weight and also increased the quantity of silk production by enhancing the feed efficacy than control. So this supplementation could be prescribed to the farmers to get more quantity of silk.

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Inhibition of inducible nitric oxide synthase (iNOS) by simvastatin attenuates cardiac hypertrophy in rats

Inhibition of inducible nitric oxide synthase (iNOS) by simvastatin attenuates cardiac hypertrophy in rats

Twenty-four adult male Wistar albino rats, with a body weight (BW) between 160 and 180 g, were supplied by the Animal Care Centre at the College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia. Rats were housed and maintained under standard controlled environmental conditions in indi- vidual plastic cages at a temperature of 25 ± 2°C on 12-h light/dark cycle throughout the study with free access to standard pelleted rat chow and tap water ad libitum. The animals were acclimatised for a period of 1 week before the start of the experiment. All the experimental procedures were conducted according to the Guidelines for the Care and Use of Laboratory Animals of the College of Medicine Research Centre (CMRC) at King Saud University and conform to the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health (NIH).

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Ionotropicaly Crosslinked and Chitosan Reinforced Losartan Potassium Loaded Complex Alginate Beads: Design, Characterization and Evaluation

Ionotropicaly Crosslinked and Chitosan Reinforced Losartan Potassium Loaded Complex Alginate Beads: Design, Characterization and Evaluation

The release of the entrapped drug from hydrogels depends on the swelling behavior, because swelling is directly proportional to drug release in case of hydrogels. As the hydrogel swells, the pores of network open and release of the entrapped solute occurs. Therefore the dynamic swelling study of the prepared beads was carried out in both phosphate buffer pH 1.2 and pH 7.4 and the results are shown in Table 3. The swelling ratio of micro beads was found to be in the range of 16% to 34%. The swelling behavior of beads was expressed as the ratio of initial weight of beads to the final weight of swollen beads as a function of time. The swelling of beads depends upon the concentration of polymer. The swelling of the beads increased with an increasing amount of polymer in the beads. In intestinal pH, the protonated amino groups of chitosan get deprotonated and at the same time carboxyl groups of alginate ionize, which weakens the electrostatic interactions, thus making

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Flow Diagnostics using Filtered Rayleigh Scattering.

Flow Diagnostics using Filtered Rayleigh Scattering.

[15] and a stable flame was ensured by the air co-flow. The FRS images of diffusion flame were acquired at each of the same five laser frequencies mentioned in previous sections. The raw FRS images at each frequency location were processed to subtract background intensities. The radial FRS signal profile is extracted from the processed images to compute the radial profile of FRS signal ratio at all possible frequency combinations. The radial temperature can be computed from the signal ratio profile at each frequency combination by scaling the signal ratio with the respective molecular weight scaling shown Table 9, and backtracking the temperature from the scaled signal ratio profile using the respective temperature dependent power-law fit shown in Table 10. It is observed that, of the ten temperature profiles obtained (one at each frequency combination), the radial temperature profile computed for 18793.18-18793.28 cm -1 frequency combination showed the best

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Oil content, fruit and seed characteristics Ethiopian Jatropha (Jatropha curacas L.) provenances

Oil content, fruit and seed characteristics Ethiopian Jatropha (Jatropha curacas L.) provenances

These seeds were found to have a relatively similar endosperm to seed shell ration ranging between 1.83 and 1.87. The consistent value of seed coat and endosperm expressed in terms of their ration is due to a significant and strong positive association (r=0.60**) of seed coat and endosperm of Jatropha seed (Table 6). The higher value was recorded for populations collected from Oromia region and the lowest was from Amhara. Endosperm weight of the seeds ranges from 5.58 g to 6.27 g. As per the person correlation coefficient analyses, seeds with higher endosperm weight was positively and strongly associated (r=0.22*) with essential oil content (Table 6). Hence, considering endosperm weight during selection and improvement program plays a significant role in maximizing oil content of Jatropha. In other words, heavier seeds have higher oil yield than the lighter ones.

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PEG-coated gold nanoparticles attenuate &beta;-adrenergic receptor-mediated cardiac hypertrophy

PEG-coated gold nanoparticles attenuate &beta;-adrenergic receptor-mediated cardiac hypertrophy

Notes: *P,0.05, **P,0.01, ***P,0.001. (A) representative M-mode echocardiography images were taken to show left ventricular wall thickness. (B) Quantitative analysis of diastolic left ventricular posterior wall thickness. (C) Quantitative analysis of hW/BW ratio. (D) Quantitative analysis of hW/Tl ratio. Data represent mean ± seM. (E) representative micrographs of myocyte cross-sectional area. (F) Quantitative analysis of myocyte cross-sectional area. (G) Quantitative analysis of aNF mrNa expression. (H) Quantitative analysis of BNP mrNa expression.

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SYNTHESIS AND CHARACTERIZATION OF CHITOSAN  GRAFT   METHACRYLONITRILE COMPOSITE

SYNTHESIS AND CHARACTERIZATION OF CHITOSAN GRAFT METHACRYLONITRILE COMPOSITE

Highly swelling polymers, which is, superabsorbent composites are hydrophilic three dimensional networks that can absorb water in the amount from 10% up to thousands of times their dry weight Po (1994). They are widely used in various applications such as drug delivery, hygienic, foods, cosmetics and agriculture (Zhou et al., 2011; Huixia et al., 2010; Raghavendra et al., 2010; Hoffman, 2002; Peppas and Harland, 1990; Kost, 1995). This accounts for increase in the worldwide production of superabsorbent polymers (SAPs) from

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