Cranes for Building Construction Projects

Cranes have come to symbolize building construction itself. They perform indispensable services in moving materials and components vertically and horizontally. Used since antiquity, their history is interrelated with the development of new power sources that replaced man and mule, first steam and later internal combustion, diesel, and electric engines. Mobile cranes can be rapidly deployed to lift heavy loads. New models with telescoping booms and all-terrain travel capability, compact urban machines, and even hybrids with tower cranes are beginning to replace the familiar lattice boom truck cranes. Mobile cranes have dominated the North American market, but a cultural change appears to be taking place toward tower cranes for building projects. Tower cranes, common in Europe for decades, are globally gaining in popularity with surging real estate developments. Ideal for dense urban environments and coming with a small footprint, they are available in a growing diversity of sizes and configurations. Sophisticated electronic controls and operator assistance devices are enhancing their safe and productive operation. While cranes occupy a central role on midrise and high-rise building projects, they operate in conjunction with other types of supporting equipment that are an essential part of the overall equipment array on today’s industrialized construction sites.     

A Review of 25 Years of CSCW Research in Healthcare: Contributions, Challenges and Future Agendas

CSCW as a field has been concerned since its early days with healthcare, studying how healthcare work is collaboratively and practically achieved and designing systems to support that work. Reviewing literature from the CSCW Journal and related conferences where CSCW work is published, we reflect on the contributions that have emerged from this work. The analysis illustrates a rich range of concepts and findings towards understanding the work of healthcare but the work on the larger policy level is lacking. We argue that this presents a number of challenges for CSCW research moving forward: in having a greater impact on larger-scale health IT projects; broadening the scope of settings and perspectives that are studied; and reflecting on the relevance of the traditional methods in this field - namely workplace studies - to meet these challenges.     

A demonstration of level-anchored ratio scaling for prediction of grip strength

Level-anchored ratio scaling, such as the Borg CR10 scale^® and the Borg CR100 scale^®, uses verbal anchors in congruence with numbers to give ratio data together with natural levels of intensity. This presupposes that the anchors possess natural positions in the subjective dynamic range and also “numerical” inter-relations. In an experiment, subjects had to produce a force of handgrip corresponding to their conception of “Strong”, followed by a “Maximal” performance. By using the previously found relationship between “Strong” and “Maximal” of 1:2 together with knowledge of the exponent in the power S-R-function (R = c × Sⁿ) for grip strength, n = 1.8, predictions of individual maximal performances were obtained. The predicted values correlated 0.76 with, and deviated only 3% (ns) from, actual maximal performances of grip strength. This result –as previously also found for aerobic capacity–gives a strong support for the use of verbal anchors, so common in category scaling, also in “ratio scaling” and that the Borg CR-scales fulfill the requirements for ratio scales. For estimation of muscular strength, such as grip strength, this present study points to the value of using submaximal determinations as a compliment to maximal performances (e.g., to obtain measures of functional capacity). The results also support the increasingly common use of the CR-methodology in other ergonomic settings concerning suitable design of tools and equipment.     

Software Assumptions Lead to Preventable Errors

Undocumented assumptions are often the cause of serious software system failure. Thus, to reduce such failures, developers must become better at discovering and documenting their assumptions. In this article, we focus on common categories of assumptions in software, discuss methods for recognizing when developers are making them, and recommend techniques for documenting them.     

Between Elderly Parents and Grandchildren—Geographic Proximity and Trends in Four-Generation Families

In an ageing society, families may have an important role in the caretaking and well-being of the elderly. Demographic changes have an impact on the size and structure of families; one aspect is how intergenerational support is distributed when there is a need for support to both older and younger generations at the same time. Another vital aspect of the provision of care for the elderly is geographic proximity. This study is oriented towards the potential “both-end carers” i.e. persons who have grandchildren in potential need of care while still having living ageing parents. The incidence of having grandchildren and having living parents at age 55 and the proximity between generations is described using Swedish register data. The results show that the share of 55-year-olds who are grandparents decreased dramatically from 70% to 35% between 1990 and 2005. As expected, more 55-year-olds have living parents—a proportion that increased from 37% to 47% during this period. As a result of delayed childbearing among the children of these cohorts, the likelihood of belonging to a four-generation family among 55-year-olds has not increased, despite increased longevity. Furthermore, most individuals live within daily reach of their kin and no evidence was found of a trend of increasing geographic distances between generations.     

Non-positive autoimmune responses against CYP2E1 in refrigeration mechanics exposed to halogenated hydrocarbons

The aim of the study was to determine if occupational exposure to hydrofluorocarbons (HFC) and hydrochlorofluorocarbons (HCFC) generates autoimmune responses against CYP2E1. HFCs and HCFCs have replaced the chlorofluorocarbons (CFC) in e.g. refrigeration installations and air-conditioning systems. During the substitution period, refrigeration mechanics reported symptoms like asthma, influenza-like reactions, and joint troubles. These symptoms resemble those of chronic inflammatory diseases with an autoimmune component. Since exposure to structurally similar chemicals, e.g. halothane, has previously been associated with autoimmune responses and diseases, autoimmunity among the refrigeration mechanics might hypothetically explain the reported inflammatory symptoms. Serum from 44 Swedish men, occupationally exposed to halogenated hydrocarbons, was screened for antibodies against CYP2E1 with enzyme-linked immunosorbent assay. Thirty of the workers had asthma, joint problems or influenza-like symptoms whereas 14 of them had no such symptoms. They were all selected from a cohort of 280 refrigeration mechanics. Unexposed, healthy, Swedish men (n=35) constituted control group. The study was approved by the Ethics Committee at Karolinska Institutet. No increase in autoantibodies against CYP2E1 was detected among the occupationally exposed workers as compared to the unexposed controls. Further, there was no difference in antibody titer between the exposed workers with symptoms and the exposed, asymtomatic workers or the unexposed controls. The present study does not completely exclude a connection between exposure and effect but makes the relation less likely at these exposure levels.     

Prof. Dr.-Ing. Dr. h. c. Franz Kollmann Zum 65. Geburtstag

Ohne Zusammenfassung     

Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry     

Influence of Oxygen During Pretreatment of Kraft Pulp with NO2

Abstract

Large additions of O₂ during the pretreatment of modified or industrial kraft pulp with NO₂ under conditions which favored an autocatalytic generation of NO₂ from produced and added HNO₃ led to a decreased viscosity after a subsequent oxygen bleaching, If the comparison was made at high kappa numbers. The difference was less apparent when the oxygen bleaching was extended. The yield of pulp at a given kappa number was reduced by large O₂ additions. An Increased yield of nitric acid contributed to these effects.

Hydrogen cyanide and ammonia were produced during the pretreatment in reactions between lignin and generated nitrogen oxides. Addition of O₂ led to decreased yields of these products.