1,926 research outputs found

    WAGE AND EMPLOYMENT FLUCTUATIONS IN THE US MANUFACTURING INDUSTRY

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    The volume of trade between the US and developing nations has increased substantially over the past three decades. The resulting fluctuations in employment and wages of domestic and foreign workers, as well as export and import trends, are in agreement with Hoeschker-Ohlin-Samuelson. We take as our base case the manufacturing industry. We find that the wages of unskilled relative to skilled US workers has increased, while overall employment of unskilled workers has decreased. We also look at a subsample of plants in the Mexican automobile industry following the implementation of NAFTA and find that exports and TFP growth have increased, in line with standard HOS theory

    Fuzzy Rough Signatures

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    Creep properties of cement and alkali activated fly ash materials using nanoindentation technique

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    This paper presents creep properties of cement and alkali activated fly ash (AAFA) paste and mortar determined from statistical analysis of nanoindentation data. Cement paste having 95 MPa compressive strength at 28 days was tested for comparison and validation with a conventional test. Using nanoindentation, the specific creep of the cement paste after one year was predicted as 18.32 microstrain/MPa. For AAFA samples, an experimental program was set up using Taguchi's Design of Experiment method to consider four parameters, silica fume, sand to binder ratio, liquid to solid ratio, and superplasticiser, each with three variations.Using ANOVA, the percentage contributions of these parameters on the creep modulus of AAFA samples are: silica fume 26%, sand to binder ratio 21%, liquid to solid ratio 22%, and superplasticiser 31%. The results using de convolution technique to identify the creep modulus of different phases of AAFA matrices show that partly-activated, non-activated slag and non-activated compact glass phases are leading the creep behaviour of AAFA samples due to their high creep modulus. Compare to other parameters, the liquid to solid ratio contributes the most to the creep property of partly-activated slag, non-activated slag and non-activated compact glass phases, that is, 51%, 89%, 68%, respectively. Sand to binder ratio and superplasticiser have minor effect on the creep behaviour. The results of the creep properties of AAFA paste were then compared with those of AAFA concrete using an upscaling process. The creep rate of AAFA concrete was defined by the creep properties of the matrix and the interface between aggregates and matrix assuming perfect bonding and slip bonding conditions. The results from the upscaling process show that the creep properties of AAFA paste from nanoindentation are representative of the long-term creep properties of AAFA concrete determined from a conventional test method

    The electrostatics of a dusty plasma

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    The potential distribution in a plasma containing dust grains were derived where the Debye length can be larger or smaller than the average intergrain spacing. Three models were treated for the grain-plasma system, with the assumption that the system of dust and plasma is charge-neutral: a permeable grain model, an impermeable grain model, and a capacitor model that does not require the nearest neighbor approximation of the other two models. A gauge-invariant form of Poisson's equation was used which is linearized about the average potential in the system. The charging currents to a grain are functions of the difference between the grain potential and this average potential. Expressions were obtained for the equilibrium potential of the grain and for the gauge-invariant capacitance between the grain and the plasma. The charge on a grain is determined by the product of this capacitance and the grain-plasma potential difference

    Eosinophils and Oral Squamous Cell Carcinoma: A Short Review

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    The eosinophil cell has been related as a prognostic indicator for cancers. However, its exact function in tumour behaviour is still not clearly defined. In the oral cavity the presence of eosinophils can be a favourable prognostic indicator as well as it may be associated with a poor prognosis. In this short review, we briefly summarize the role of the eosinophils in the general context of immunoregulation and its relation to oral squamous cell carcinoma

    Aspects of post conflict development in Jaffna and the Vanni

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    „A River for Jaffna‟, called the Arumugam Plan, after a retired Deputy Director of Irrigation and former General Manager/Director of the Water Resources Board, under retired Chief Justice Hema Basnayake, Chairman, consists of Elephant Pass lagoon scheme, Thondamannar barrage and Ariyalai barrage. Begun in 1950‟s, it was never fully completed. In 2008, although LTTE held Elephant Pass, President Mahinda Rajapakse ordered restoration of Thondamannar and Ariayalai barrages; and the multiple benefits are evident today. After the Nandikadal military victory in May 2009, „Jaffna Water Supply and Sanitation project‟ was announced in the National Water Supply and Drainage Board, designed by Snowy Mountains Engineering Corporation, Australia, which does not make full use of the River for Jaffna scheme. Water from Iranamadu reservoir near Kilinochchi, will be pumped to Jaffna, and treated in imported large-scale, centralized Treatment plant. Presently, efforts are being made to combine the two schemes with massive savings in the huge ADB loan, by drawing water from Elephant Pass lagoon after completing that scheme, and using multiple, decentralized Treatment Plant developed in the R&D division of the NWS&DB. However, unexpectedly, a non-career diplomat, qualified in hydro-ecology, and river development work, has condemned the River for Jaffna project. This paper discusses these issues

    The impact of urban morphology on the building energy consumption and solar energy generation potential of university dormitory blocks

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    Urban morphology is a major factor affecting building energy consumption and solar potential in the urban block. The aim of this research was to evaluate the impact of urban morphology on both building energy consumption and solar energy generation potential for university dormitory blocks in Wuhan. This paper proposed a classification method for dormitory blocks, calculated the building energy consumption and solar energy generation potential of 55 blocks, and analyzed the correlation between urban morphology and three energy performance indicators: Energy Use Intensity (EUI), Solar Energy Generation Intensity (SEGI) and Net Energy Use Intensity (NEUI). Multiple regression models were used to predict energy performance by urban morphological parameters. The results indicate that different block types could lead to up to 12.25% difference in EUI, and 35.85% significant difference in building NEUI with the deployment of photovoltaic (PV) panels. The EUI is mainly affected by three 2 morphological parameters, which are Average length of block, Shape factor and Building density; while the SEGI and NEUI are mainly affected by Average height of block, Shape factor and Sky view factor. This study could serve as guidelines for planners and policymakers in campus planning and architectural design to improve building energy conservation at block-scale

    The relationship between the piriformis muscle, low back pain, lower limb injuries and motor control training among elite football players

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    Objectives: Australian Football League (AFL) players have a high incidence of back injuries. Motor control training to increase lumbopelvic neuromuscular control has been effective in reducing low back pain (LBP) and lower limb injuries in elite athletes. Control of pelvic and femoral alignment during functional activity involves the piriformis muscle. This study investigated (a) the effect of motor control training on piriformis muscle size in AFL players, with and without LBP, during the playing season, and (b) whether there is a relationship between lower limb injury and piriformis muscle size. Design: Stepped-wedge intervention. Methods: 46 AFL players participated in a motor control training programme consisting of two 30. min sessions per week over 7-8 weeks, delivered across the season as a randomised 3 group single-blinded stepped-wedge design. Assessment of piriformis muscle cross-sectional area (CSA) involved magnetic resonance imaging (MRI) at 3 time points during the season. Assessment of LBP consisted of player interview and physical examination. Injury data were obtained from club records. Results: An interaction effect for Time, Intervention Group and LBP group (F=3.7, p=0.03) was found. Piriformis muscle CSA showed significant increases between Times 1 and 2 (F=4.24, p=0.046), and Times 2 and 3 (F=8.59, p=0.006). Players with a smaller increase in piriformis muscle CSA across the season had higher odds of sustaining an injury (OR. =1.08). Conclusions: Piriformis muscle size increases across the season in elite AFL players and is affected by the presence of LBP and lower limb injury. Motor control training positively affects piriformis muscle size in players with LBP

    Performance-enhancement of phase change materials for energy conservation in the built environment : a state-of-the-art review

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    Energy conservation has become a critical issue in the world today as strong economic growth is unfeasible without a sustainable strategy of energy conservation. Apart from long-term environmental impact, a well-managed strategy for energy consumption even results in improvement of the financial performance in the short term. Phase change materials (PCMs) with its capacity of storing thermal energy as latent heat is a viable approach of the utilization of solar heat, a green source of energy, and the optimization of energy consumption in buildings. However, the obstacle that prevents PCMs from being applied widely in practice comes from its poor performance in terms of heat transfer and shape stabilization. This article, therefore, presents a critical review of PCM and effective methods to boost its performance in terms of shape stabilization and transient heat transfer

    Experimental investigation on the behavior of RC panels retrofitted with polymer coatings under blast effects

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    Elastomeric polymers (such as polyurea and polyurethane) are finding relevance in retrofitting applications for structures being subjected to blast and impact loadings. This approach, an alternative to various existing retrofitting techniques, capitalises on the elastomeric properties, high strain capacity, high ductility and strength of the polymers, as well as on the ability of the coating layer to act as a shield in containing debris and fragments from the blast. This paper presents the findings from an experimental study undertaken to evaluate the effectiveness of using polyurea coatings to enhance the blast resistance of reinforced concrete (RC) panels. The performed experimental blast trials, designated as Vietnam Trial 2, were conducted in Vietnam with the collaboration from the Vietnam Institute for Building Science and Technology (IBST). Four RC panels with dimensions of 1700 (L) 1000 (W) 60 (T) mm, were tested during the trials. Of these, one panel was an unretrofitted panel while the remaining three were coated with polyurea albeit with a variation in the coating thickness and location. All the panels were subjected to blast loads resulting from the detonation of 1.0 kg Ammonite charge placed at 1.0 m stand-off. The behaviour and responses of various polyurea coated RC panels were compared to the unretrofitted RC panels in terms of panel’s deflections, crack formation and damage to the polyurea coating layers. The findings from the experiments indicated that proposed technique of using polyurea coating to retrofit RC structural elements is practicable and feasible to enhance the capacity of structures against blast loading. A higher level of protection is provided when the protective coating is applied on the blast-facing face of the structure. It was also observed that the bond between concrete and the polymer did not damage even after the the application of the blast loads. These findings assert the possibility of using the proposed technique as a practical alternative to the existing techniques in strengthening structures being subjected to blast effects
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