Prognostic factors for chronic neck pain in persons with minor or moderate injuries in traffic accidents

Prognostic factors for chronic neck pain were identified in a prospective Norwegian insurance cohort comprising 636 persons with minor or moderate traffic injuries. One questionnaire was used at baseline and another at 3 years post-injury. Daily severe or very severe neck pain at three years follow up was defined as chronic neck pain. Eight significant independent prognostic factors for chronic neck pain were identified: (1) rear-end or frontal and rear-end collision, odds ratio (OR): 4.10 (95% confidence interval (CI): 1.72-10.82); (2) neck and/or shoulder pain before the accident, OR: 2.38 (95% CI: 1.07-5.37); (3) post-accident (a) memory and concentration problems, OR: 4.62 (95% CI: 1.99-11.20), (b) bodily tension, OR: 3.43 (95% CI: 1.49-8.42), (c) difficulties to climb stairs, OR: 5.03 (95% CI: 1.77-14.95), (d) difficulties to bend forward, OR: 4.85 (95% CI: 2.06-11.79), (e) difficulties to do heavy labour, OR: 3.70 (95% CI: 1.24-11.64); (4) beliefs in future work disability, OR: 2.64 (95% CI: 1.11-6.48). The results indicate that development of chronic neck pain is influenced by pre-accident neck and/or shoulder pain, the impact of the collision, as well as post-accident symptoms, perceived impaired function and pessimism for the future ability to work.     

A Crystalline Si3N4/Amorphous Si3N4 Composite

A composite consisting of elongated α-Si₃N₄ crystallites (5–50 (Am in diameter) embedded in an amorphous Si₃N₄ matrix was synthesized by chemical vapor deposition. The hardness and indentation fracture toughness of the amorphous matrix and of the composite have been evaluated at temperatures from ambient to 1200°C. It was found that the crystallites have relatively little influence on the hardness and indentation fracture toughness when the surrounding matrix is amorphous. However, a 1400°C heat treatment of the material results in a matrix consisting of small crystals (100 nm in diameter) surrounded by carbon-containing regions which appear to be amorphous in the TEM; TEM and EELS in nearby triple points revealed the presence of amorphous carbon. After heat treatment, the indentation fracture toughness at ambient and at 1200°C is increased due to extensive microcracking. The Vickers hardness at 1200°C also increased significantly as a result of the heat treatment. The relationship between the mechanical properties and the microstructure is discussed.     

An excavation method for large vertical cylindrical caverns

Construction of underground storage chambers in rock has traditionally adopted a construction-oriented approach; the cavern design and the method of excavation have been governed by the capabilities of the equipment available. One example is oil storage in unlined horizontal caverns. Today, however, equipment is no longer a limiting factor. The time has come to integrate the construction and operational aspects in the design process. This paper presents a construction concept developed for large vertical rock caverns with a circular or elliptical horizontal cross-section. The method of excavation, called PBM (Pillar Blasting Method), is condensed into a few main operations which are geometrically separated but overlapping in time. PBM is characterized by two main working sites per cavern, and by long-hole bench-drilling, massive blasting rounds, continuous loading and easy ventilation. Recent developments in drilling and blasting techniques are incorporated, such as the water-driven in-the-hole hammer and the electronic ignition system. PBM enables a high rate of excavation and provides a satisfactory working environment with respect to labour safety and human health (a limited exposure to large openings, no exposure to oil mist and to combustion and explosive fumes, etc). Considerable construction cost savings and time savings may thus be achieved compared to conventional methods of excavation for vertical and horizontal caverns of equal storage volume. A preliminary PCT patent (application No PCT/SE95/00324) has been granted. Examples of applications are fresh-water reservoirs, natural gas reservoirs, subsurface hydroelectric pump power plants, and similar objects which require a large underground storage space in preferably unlined rock caverns.     

The Compelling Case for Indentation as a Functional Exploratory and Characterization Tool

The utility of indentation testing for characterizing a wide range of mechanical properties of brittle materials is highlighted in light of recent articles questioning its validity, specifically in relation to the measurement of toughness. Contrary to assertion by some critics, indentation fracture theory is fundamentally founded in Griffith–Irwin fracture mechanics, based on model crack systems evolving within inhomogeneous but well‐documented elastic and elastic–plastic contact stress fields. Notwithstanding some numerical uncertainty in associated stress intensity factor relations, the technique remains an unrivalled quick, convenient and economical means for comparative, site‐specific toughness evaluation. Most importantly, indentation patterns are unique fingerprints of mechanical behavior and thereby afford a powerful functional tool for exploring the richness of material diversity. At the same time, it is cautioned that unconditional usage without due attention to the conformation of the indentation patterns can lead to overstated toughness values. Limitations of an alternative, more engineering approach to fracture evaluation, that of propagating a precrack through a “standard” machined specimen, are also outlined. Misconceptions in the critical literature concerning the fundamental nature of crack equilibrium and stability within contact and other inhomogeneous stress fields are discussed.     

Effects of transference work in the context of therapeutic alliance and quality of object relations.

Objective: Transference interpretation is considered as a core active ingredient in dynamic psychotherapy. In common clinical theory, it is maintained that more mature relationships, as well as a strong therapeutic alliance, may be prerequisites for successful transference work. In this study, the interaction between quality of object relations, transference interpretation, and alliance is estimated. Method: One hundred outpatients seeking psychotherapy for depression, anxiety, and personality disorders were randomly assigned to 1 year of weekly sessions of dynamic psychotherapy with transference interpretation or to the same type and duration of treatment, but without the use of transference interpretation. Quality of Object Relations (QOR)–lifelong pattern was evaluated before treatment (P. H?glend, 1994). The Working Alliance Inventory (A. O. Horvath & L. S. Greenberg, 1989; T. J. Tracey & A. M. Kokotovic, 1989) was rated in Session 7. The primary outcome variable was the Psychodynamic Functioning Scales (P. H?glend et al., 2000), measured at pretreatment, posttreatment, and 1 year after treatment termination. Results: A significant Treatment Group × Quality of Object Relations × Alliance interaction was present, indicating that alliance had a significantly different impact on effects of transference interpretation, depending on the level of QOR. The impact of transference interpretation on psychodynamic functioning was more positive within the context of a weak therapeutic alliance for patients with low quality of object relations. For patients with more mature object relations and high alliance, the authors observed a negative effect of transference work. Conclusion: The specific effects of transference work was influenced by the interaction of object relations and alliance, but in the direct opposite direction of what is generally maintained in mainstream clinical theory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

EFFECT OF PRECIPITATION TEMPERATURE ON THE COMPOSITION OF N-HEPTANE ASPHALTENES Part 2

ABSTRACT

Petroleum asphaltenes precipitated by n-heptane at temperatures between ambient and 80^°C from two crude oils have been characterized regarding hydrocarbon structures using ¹H and ¹³C nmr, and fluorescence spectroscopy. This indicates a very complex and apparently very small change in structural features except for a molecular weight increase as more material stays in solution at elevated temperature. Aromaticity increase and apparently alkyl chains diminish. The latter trend is however affected by the structural equation used. According to the fluorescence spectroscopy the content of large and complex chromophores increases but a significant effect of the presence of porphyrins on the spectra is also observed. The data is analyzed in combination with previous characterizations of the same asphaltenes presented in the first part of this work (Andersen, 1994). This indicates that as smaller molecules are extracted at elevated temperature the precipitated asphaltenes tend to associate more. This implys that these small molecules block association sites which therefore become available for further association at elevated temperature. For Boscan part of the smaller easy to extract porphyrins may have this behavior.     

Variation in Composition of Subfractions of Petroleum Asphaltenes

ABSTRACT

Boscan asphaltenes were precipitated from the crude oil using mixtures of toluene and heptane at temperatures of 24, 50, and 80°C. Another process of extracting solid n-heptane asphaltenes (24°C) using the same solvent systems and temperatures was also investigated. Asphaltene yield is different by the two processes at similar conditions although both increases in temperature or toluene content lead to lower solid yield. This way the asphaltene continuum was investigated from incipient flocculation to total n-heptane precipitated asphaltenes. The asphaltenes were analyzed using elemental analysis, fluorescence spectroscopy, vapor pressure osmometry, and HPLC size exclusion chromatography. The distribution of porphyrins was also measured using absor-bance spectroscopy. The asphaltenes were found to follow a regular trend in elemental ratios, H/C and N/C, indicating increased aromaticity and nitrogen content as the solid yield decreases. Also the molecular weight was seen to increase. Size exclusion chro-matograms and fluorescence spectra were found to be different comparing solids from the two separation processes. This indicates that the asphaltene fractions obtained by extraction of solid asphaltenes are altered relative to asphaltenes obtained by ordinary precipitation. The porphyrin concentration was found to diminish rapidly with solid yield decrease in both precipitation and extraction experiments, the latter fractions, however, containing significantly less asphaltenes indicating an adsorption step in the coprecipitation of porphyrins. Soluble fractions were found to exhibit relatively low molecular weights and an apparent lack of indications of association up to a point of solubles exceeding 50 % of the total asphaltenes. The-latter have implications for the further understanding and experimental investigation. of the associating nature of asphaltenes such as concentration effects during analytical characterization.     

A Group Theoretical Analysis of Conformational Flexibility

The chemical identity group of a conformationally flexible molecule has very special properties. An analysis of its group structure leads to a detailed interpretation of the properties of the conformationally flexible molecules and their permutation isomers. In contrast to conventional conformational analysis our treatment of conformationally flexible molecules on the basis of chemical identity groups emphasizes ensembles of interconverting conformers. This leads to an interpretation of the observed increase in “symmetry” through conformational flexibility.