A Study of the Polishing Characteristics of Limestone and Sandstone Aggregates in Regard to Pavement Slipperiness

The coefficient of friction on dry highway surfaces regardless of stone composition and texture has in most cases been at least 0.6 or above. However, some of these same surfaces when lubricated by a small amount of water have given test results dangerously lower. Some interesting theoretical aspects of this situation are presented here along with results from a laboratory study of the fundamental factors affecting tractive friction. A machine is described for measuring the coefficient of friction between the plane surfaces of four-inch diameter stone specimens and a rubber annulus of slightly smaller diameter. Measurements were made both wet and dry on finely polished surfaces and on surfaces ground with 80 and 150 grit Carborundum. Tests were conducted under varying loads and speeds. A 60-degree reflectometer was used to evaluate texture and roughness of the plane surfaces. Reflectivity (gloss) values correlated significantly with wet friction values in the highly polished ranges. Tests were conducted on representative samples of four limestones and two sandstones. Coefficient of friction values of 0.01 and lower were measured on finely polished wet limestone surfaces. Sandstones subjected to the same polishing action averaged about 0.22 when wet. In another series of testing, the specimens were abraded with a coarse Carborundum grit, and the wet friction values were consistently between 0.6 and 0.7 for both limestones and sandstones. For further comparison a piece of plate glass was abraded with this same material, and it too measured within the above limits. Dry friction values remained fairly constant regardless of type of stone or texture. Test results reveal the tendency for fine grained particles bound in a matrix of similar hardness to polish more readily and to a greater extent than hard particles such as quartz bound in a soft matrix. Limestones, being typical of the former condition, polished easier than sands tones

Biomechanical Demands and Postural Control During Exercises Commonly Performed by Older Adults in Falls Prevention Programs

Exercise programs that are individualized and moderately challenge balance to address falls risk factors are recommended for preventing falls in community-dwelling older adults. Little is known regarding the biomechanical and postural control demands in exercises commonly performed in falls prevention programs. Twenty-two non-sedentary, healthy older adults (11 men, 11 women, mean age 69 5 years) performed 5 standing exercises (hip abduction (HA), side step (SS), squat (SQ), forward lunge (FL), and side lunge (SL)) commonly performed in efficacious falls prevention programs. A biomechanical analysis of the dominant limb was performed using motion-capture and kinetic data to calculate peak joint angles and peak net joint moments, peak power and total work at the ankle, knee and hip in multiple planes. Center of pressure (CoP) measures of mean time-to-boundary (TTB), mean velocity, path length, and 95% confidence ellipse area were also analyzed during performance of the SS and HA exercises. Significant differences and some degree of ranking in characteristics of biomechanical demand was found along with significant differences in characteristics of postural control demand between the SS and HA. Greater joint angles at the ankle, knee and hip were generally found during the SQ exercise. The FL demonstrated characteristics of greater hip extension demand while the SL demonstrated greater knee extension moment. The SS and HA exercises generally demonstrated greater or similar demand to other exercises in sagittal plane ankle and frontal plane hip kinetics. Differences in characteristics of postural control were found between the HA and SS exercises. Study findings suggest the SS exercise provided greater challenge to postural stability in the AP direction while the HA moved the CoP to a greater extent and provided greater challenge to postural control in the ML direction than the SS. Varying lower extremity joint angles, kinetics, and characteristics of postural control found during performance of the selected exercises suggest that combinations of these exercises may assist clinicians in tailoring exercise programs. Our results also suggest that postural control demand in the SS and HA may be similar to balance activities often included in falls prevention programs. Thus, clinicians may address falls risk factors related to mobility and balance deficits in older adults by including the selected exercises in a fall prevention program

The development of corporate tax structures in the European Union from 1998 to 2015 : qualitative and quantitative analysis

Ongoing tax reform processes, competitive pressures and the consequences of the financial and sovereign debt crisis have considerably shaped the tax systems of the Member States of the European Union in the last two decades. Our paper combines a qualitative and quantitative analysis of the development of European tax structures based on a unique and comprehensive dataset for the EU-25 Member States between 1998 and 2015. Especially among the EU-15 Member States, we still find evidence for the often-cited trend of tax rate cut cum tax base broadening. In this context, we identify interest deduction limitation rules and loss provisions as main drivers of tax base broadening. Furthermore, the quantitative analysis of effective tax burden scenarios shows that Member States seem to additionally rely on an increased taxation of dividends to balance possible revenue losses associated with reduced corporate income tax rates

Telehealth Assessment of Frailty in Community Dwelling Older Adults using the Modified Physical Performance Test (Poster)

Frailty in Older Adults ● Frailty is a health condition that effects increasing numbers of the population past the age of 65 ● The modified Physical Performance Test (mPPT) is a test that assesses multiple dimensions of physical function with different levels of difficulty. It has been shown to assess frailty in an older adult population. ● Due to health care barriers, it may be advantageous to assess individuals via telehealth. ● It is critical to determine the concurrent validity of telehealth delivery of mPPT with that of a clinical setting to determine if it can increase access to car

Breaking borders? The European Court of Justice and internal market

Upon more than 400 judgements on direct taxation, the case law of the European Court of Justice has considerably shaped Member States’ tax systems. Based on Member States’ tax law adjustments in the context of four landmark rulings on corporate income taxation, we analyse whether case law is a suitable instrument to eliminate tax distortions towards the realisation of a European internal market. Our analysis is based on effective tax burdens using the Devereux/Griffith methodology. Overall, we find that due to Member States’ mostly heterogeneous adjustments and varying levels of compliance, cross-border investment continues to be discriminated in some Member States following the Marks & Spencer and National Grid Indus judgements. In addition, differences in the general availability of the rules under scrutiny and design of related provisions, cross-country differences in effective tax burdens and hence distortions to the internal market might persist. We conclude that a comprehensive harmonisation of Member States’ tax systems by way of positive integration would be necessary to sustainably eliminate tax obstacles to cross-border business activities

Perturbation-Based Balance Training added to a Fall Prevention Exercise Program and its Effect on Fall Risk and Fear of Falling in Community-Dwelling Older Adults

Background: ● Falls lead to decreased independence, increased disability, and increased risk of death ● Falls occur in more than one out of four older adults each year Research Suggests: ● 50 hours of a structured strength and balance exercise program supplemented with fall prevention education over 12 weeks decreases fall risk in community dwelling older adults ● One session of perturbations provided at the appropriate dosage can decrease fall risk by 50%, with multidirectional perturbations having the greatest benefit Hypothesis: ● Adding one session of perturbation-based training to a structured strength and balance exercise program will reduce the risk of falls and fear of falling in community dwelling older adult

Genomics of Aerobic Cellulose Utilization Systems in Actinobacteria

Cellulose degrading enzymes have important functions in the biotechnology industry, including the production of biofuels from lignocellulosic biomass. Anaerobes including Clostridium species organize cellulases and other glycosyl hydrolases into large complexes known as cellulosomes. In contrast, aerobic actinobacteria utilize systems comprised of independently acting enzymes, often with carbohydrate binding domains. Numerous actinobacterial genomes have become available through the Genomic Encyclopedia of Bacteria and Archaea (GEBA) project. We identified putative cellulose-degrading enzymes belonging to families GH5, GH6, GH8, GH9, GH12, GH48, and GH51 in the genomes of eleven members of the actinobacteria. The eleven organisms were tested in several assays for cellulose degradation, and eight of the organisms showed evidence of cellulase activity. The three with the highest cellulase activity were Actinosynnema mirum, Cellulomonas flavigena, and Xylanimonas cellulosilytica. Cellobiose is known to induce cellulolytic enzymes in the model organism Thermobifida fusca, but only Nocardiopsis dassonvillei showed higher cellulolytic activity in the presence of cellobiose. In T. fusca, cellulases and a putative cellobiose ABC transporter are regulated by the transcriptional regulator CelR. Nine organisms appear to use the CelR site or a closely related binding site to regulate an ABC transporter. In some, CelR also regulates cellulases, while cellulases are controlled by different regulatory sites in three organisms. Mining of genome data for cellulose degradative enzymes followed by experimental verification successfully identified several actinobacteria species which were not previously known to degrade cellulose as cellulolytic organisms