Translational Invariance and the Anisotropy of the Cosmic Microwave Background

Primordial quantum fluctuations produced by inflation are conventionally assumed to be statistically homogeneous, a consequence of translational invariance. In this paper we quantify the potentially observable effects of a small violation of translational invariance during inflation, as characterized by the presence of a preferred point, line, or plane. We explore the imprint such a violation would leave on the cosmic microwave background anisotropy, and provide explicit formulas for the expected amplitudes $$ of the spherical-harmonic coefficients.Comment: Notation improve

Spontaneous Lorentz Violation and the Long-Range Gravitational Preferred-Frame Effect

Lorentz-violating operators involving Standard Model fields are tightly constrained by experimental data. However, bounds are more model-independent for Lorentz violation appearing in purely gravitational couplings. The spontaneous breaking of Lorentz invariance by the vacuum expectation value of a vector field selects a universal rest frame. This affects the propagation of the graviton, leading to a modification of Newton's law of gravity. We compute the size of the long-range preferred-frame effect in terms of the coefficients of the two-derivative operators in the low-energy effective theory that involves only the graviton and the Goldstone bosons.Comment: 11 pages, no figures, revtex4. v4: Replaced to match version to appear in Phys. Lett. B (minor corrections of form

Use of Viscoelastic Changes to Demonstrate the Relationship Between Drying Parameters – A Preliminary Study

Dynamic mechanical thermal analysis (DMTA) is routinely used for mechanical analysis by the polymer industry to provide information on the viscoelastic properties of a material. This report reveals how DMTA has been used to further previous studies by providing insight into the differences between post-tanned leathers (chromium and chromium-free). It demonstrates the potential to correlate the results with an industrial application such as optimization of the drying conditions during cell rotary conditioning (CRC). DMTA can indicate leather fiber response to changes in atmospheric humidity and temperature, potentially facilitating real-time adaptation of conditions during leather drying. Initial DMTA results show that post-tanning, particularly fatliquoring, changes the rate of drying and allows scientists to advise on optimal leather drying conditions based on viscoelastic changes

Investigating the Cell Rotary Conditioning Mechanism Using Dynamic Mechanical Thermal Analysis

Jeyapalina et al. established that dynamic mechanical thermal analysis (DMTA) can be used to gauge the progression of leather drying. This work has now been advanced in order to understand the mechanism surrounding sorption/desorption of moisture during cell conditioning, e.g., cell rotary conditioning (CRC). This paper will demonstrate how the use of DMTA could be used to monitor changes in leather stiffness. A gravimetric moisture analysis was performed on identical leather samples to gauge the progression of desorption. The change in storage modulus (E’) was coupled to the moisture content (leather moisture and atmospheric relative humidity) to obtain a better understanding of the physical properties (specifically stiffness) of leather during a drying process. The research presented illustrates how DMTA can indicate leather fiber response to changes in atmospheric humidity and facilitate real-time adaptation of drying conditions during leather dehydration. The use of a cell conditioning system allows a tanner to control the flexibility of the material through the tension applied and the drying conditions. DMTA shows that the favorable conditions inside a CRC unit result in detectable changes to the leather fiber, similar to findings by Abrahamson and Williams-Wynn. Using this technique a researcher can dry chromium-containing and chromium-free leathers in a manner that is highly customizable to produce desired physical properties. Difficulties experienced in chromium-free leathers can also be investigated in detail using this technique

The use of Profilometry to Characterise the Leather Surface

The quality of the finished leathers is often determined based on the grain characteristics or pattern. The grain characteristics of leathers vary according to the age of the animal, breed, gender, climate, animal husbandry practices and processing conditions. However, the assessment of the leather surface or grain characteristics is often very subjective. In this study, the grain characteristics were determined using a profilometry technique. Profilometry, a metrological method, is essentially the measurement or assessment of surface texture and is linked to its friction and wear properties. The aim of the study was to define and grade the leather surface based on a given scale as well as to analyse the effect of various leather making operations, including tanning, on the grain texture of leather of species from different origins.Hides (bovine) and skins (goat) were subjected to various processing conditions, including extreme conditions, such as extended liming processes and shrunken grain tannage. The surface topography of the grain surface of the manufactured leather was analysed using a Zeta optical profilometer. A scanning electron microscopy was also used to observe the grain characteristics of the produced leather to verify the 3-dimensional stitched scans produced by the profilometer. The results showed a technique that can be used in forensic, quality control and research contexts to provide tanners an indication of the impact of their processing on the grain pattern of their leather. Key words: profilometry, grain characteristics, surface profile, texture.

The use of Profilometry to Characterise the Leather Surface

The quality of the finished leathers is often determined based on the grain characteristics or pattern. The grain characteristics of leathers vary according to the age of the animal, breed, gender, climate, animal husbandry practices and processing conditions. However, the assessment of the leather surface or grain characteristics is often very subjective. In this study, the grain characteristics were determined using a profilometry technique. Profilometry, a metrological method, is essentially the measurement or assessment of surface texture and is linked to its friction and wear properties. The aim of the study was to define and grade the leather surface based on a given scale as well as to analyse the effect of various leather making operations, including tanning, on the grain texture of leather of species from different origins.Hides (bovine) and skins (goat) were subjected to various processing conditions, including extreme conditions, such as extended liming processes and shrunken grain tannage. The surface topography of the grain surface of the manufactured leather was analysed using a Zeta optical profilometer. A scanning electron microscopy was also used to observe the grain characteristics of the produced leather to verify the 3-dimensional stitched scans produced by the profilometer. The results showed a technique that can be used in forensic, quality control and research contexts to provide tanners an indication of the impact of their processing on the grain pattern of their leather. Key words: profilometry, grain characteristics, surface profile, texture.

A telerobotic system for automated assembly of large space structures

Future space missions such as polar platforms and antennas are anticipated to require large truss structures as their primary support system. During the past several years considerable research has been conducted to develop hardware and construction techniques suitable for astronaut assembly of truss structures in space. A research program has recently been initiated to develop the technology and to demonstrate the potential for automated in-space assembly of large erectable structures. The initial effort will be focussed on automated assembly of a tetrahedral truss composed of 2-meter members. The facility is designed as a ground based system to permit evaluation of assembly concepts and was not designed for space qualification. The system is intended to be used as a tool from which more sophisticated procedures and operations can be developed. The facility description includes a truss structure, motionbases and a robot arm equipped with an end effector. Other considerations and requirements of the structural assembly describe computer control systems to monitor and control the operations of the assembly facility

Corporate Sustainability Disclosure: A Leather Industry Perspective

This study aims to identify and compare the key social, economic and environmental sustainability practices in the leather industry. Content analysis was used to analyse extracted sustainability information from either the website, annual report, sustainability report or corporate social responsibility report of six leather-related companies. Review of existing literature assisted in categorising different practices under social, economic and environmental sustainability, while an identification of patterns among practices followed. Findings reveal that companies are observing a good practice of either dedicating a section of their website to revealing their sustainability activities or utilising their sustainability reports or annual reports. Energy efficiency, waste management and reduction of greenhouse gases emission were the most occurring environmental sustainability practices. Health and safety occurred as the dominant social sustainability practice, while economic sustainability practices have not been well defined, providing an opportunity for future research. The study provides a useful resource for managers and companies in the leather supply chain to learn from brands that have been embarking on sustainability efforts and assist them to a better understanding of the concept, in readiness for strategy formulation, implementation and reporting

The Evaluation of the Detection of Cr(VI) in Leather

The topic of hexavalent chromium (Cr(VI)) in leather has been debated throughout the whole supply chain for years. However, its significance has recently increased due to proposed changes in European legislation concerned with skin-sensitising substances suggesting that acceptable Cr(VI) concentrations in leather goods should be lowered from 3 mg kg−1 to 1 mg kg−1. The proposition of a stricter limit and current analytical difficulties created the need for a review of current standard test methods. The research presented in this paper investigates both the colorimetric (Part 1) and chromatographic (Part 2) methods under BS EN ISO 17075. The focus of the study was to identify possible sources of interference leading to large statistical variance in results and to define the limit of quantification with respect to the proposed new compliance limit. This study into the colorimetric method has shown that the presence of Cr(III), dyes, and proteins can be significant interferences, becoming critical at low Cr(VI) concentrations. Dilution factors worsen the problem of detecting low concentrations: a reliable quantitative detection of 0.01 mg kg−1 and 0.003 mg kg−1 Cr(VI) in solution are required at the 3 mg kg−1 and 1 mg kg−1 compliance limits in leather, respectively. BS EN ISO 17075 part 1 was shown to be incapable of reliably resolving to 3 mg kg−1 or below in leather. Part 2 shows a marked improvement in detection limits and reliability; however, data suggest that 1 mg kg−1 Cr(VI) is not reliably detectable in leather. Suggested improvements to the established test methods and a possible alternative are discussed