Job level risk assessment using task level strain index scores: a pilot study.

This paper explores 2 methods of modifying the Strain Index (SI) to assess the ergonomic risk of multi-task jobs. Twenty-eight automotive jobs (15 cases and 13 controls) were studied. The first method is based on the maximum task SI score, and the second method is modeled on the NIOSH Composite Lifting Index (CLI) algorithm, named cumulative assessment of risk to the distal upper extremity (CARD). Significant odds ratios of 11 (CI 1.7-69) and 24 (CI 2.4-240) were obtained using the modified maximum task and CARD, respectively. This indicates that modification of the SI may be useful in determining the risk of distal upper extremity injury associated with a multi-task job.     

Cesium isotope ratios as indicators of nuclear power plant operations

There are multiple paths by which radioactive cesium can reach the effluent from reactor operations. The radioactive ¹³⁵Cs/¹³⁷Cs ratios are controlled by these paths. In an effort to better understand the origin of this radiation, these ¹³⁵Cs/¹³⁷Cs ratios in effluents from three power reactor sites have been measured in offsite samples. These ratios are different from global fallout by up to six fold and as such cannot have a significant component from this source. A cesium ratio for a sample collected outside of the plant boundary provides integration over the operating life of the reactor. A sample collected inside the plant at any given time can be much different from this lifetime ratio. The measured cesium ratios vary significantly for the three reactors and indicate that the multiple paths have widely varying levels of contributions. There are too many ways these isotopes can fractionate to be useful for quantitative evaluations of operating parameters in an offsite sample, although it may be possible to obtain limited qualitative information for an onsite sample.     

Stable carbon isotope variability in marine macrophytes and its implications for food web studies

Stable carbon isotope ratios (¹³C) of eelgrass Zostera marina and of kelp Laminaria longicruris showed considerable variation in time and space. The isotopic composition of Z. marina varied seasonally from a mean of-6 for leaves formed in June to a mean of-10 for leaves formed in February. The maximum range for individual leaves was from-5 to-11.4. Once a leaf was fully formed, its isotopic composition appeared not to change. In L. longicruris there was no clear seasonal pattern of variation, but in any given blade there was a spatial pattern of variation, with the thickened central band tending to be least negative and the margins most negative. In one blade the range was from-12 to-20. Since this range overlaps values that are found in various other macrophytes and in seston, the value of the stable carbon isotope ratio as a tracer in food webs involving macroalgae is questioned. For Z. marina, in which the values are seasonally predictable, the technique may be useful if interpreted with care. The most probable explanation of variation in the ratios is differential storage of biochemical components of different isotopic compostion.     

Ecological energetics of the seaweed zone in a marine bay on the Atlantic coast of Canada. I. Zonation and biomass of seaweeds

An intertidal and underwater survey of the zonation of seaweed in St. Margaret's Bay, NovaScotia, Canada showed 8 major zones as one proceeded away from shore: (1) Fucus and Ascophyllum; (2) Chorda with filamentous browns; (3) Chondrus crispus; (4) Zostera marina; (5) Laminaria digitata with L. longicrusis; (6) Laminaria longicruris; (7) L. longicruris with Agarum cribrosum; (8) Agarum cribrosum with Ptilota serrata. Zostera occurred at the same level as O. crispus but replaced it in sheltered water. Ascophyllum was more abundant in sheltered water. L. digitata was confined to the more exposed, steeper shore. The average horizontal extent of the seaweed zone was 369 m, and the greatest depth of significant amounts of seaweed 20 to 30 m. Laminaria longicruris contributed 36% of the total biomass, and Laminaria spp. and Agarum together constituted 83%, while intertidal seaweeds contributed less than 10% of the biomass. The estimated average total biomass per m of shore line was 1,481 kg fresh weight, 326 kg dry weight, 98 kg carbon, or 980x10³ kcal. When averaged over the whole area of the bay, the corresponding figures were 1.38 kg/m² fresh weight, 0.30 kg/m² dry weight, 91 g/m² carbon or 912 kcal/m². Dry matter of Laminaria was 15 to 27% of fresh weight in blades, 10 to 12% in stipes. The dry matter content of blades was least in spring and highest in autumn, but carbon content and calorific value of dry matter showed little difference with species or season.Contribution to the International Biological Programme CCIBP 108.Bedford Institute Contribution BI 249.     

The role of isopods and amphipods in the initial fragmentation of eelgrass detritus in Nova Scotia,Canada

Daytime observations on the isopods Idotea phosphorea and I. baltica and the amphipod Gammarus oceanicus held in laboratory microcosms showed that I. phosphorea and G. oceanicus spent 45% and 30% respectively, of their active time feeding on dead, intact eelgrass leaves which had been recently released from plants. I. baltica spent 41% of its active time consuming intact green leaves. The shredding of intact dead leaves by I. phosphorea and G. oceanicus resulted in production of small detrital particles which were liberated from the faeces of the invertebrates and this type of feeding led to the breakdown of whole leaves. Field experiments which separated the effects of shredding by invertebrates and grinding by waves and ice on the loss of weight from leaf packs showed that relative to controls isopods significantly increased weight loss from dead leaves. Loss of weight from leaf packs exposed to both biotic and physical shredding forces was not significantly different from that found on those exposed only to shredding by isopods. However, trends in the data indicated that fragmentation of whole, dead leaves in the field probably is a result of the synergistic effects of shredding by invertebrates and physical factors, particularly ice grinding. The role played by invertebrates in fragmenting intact, dead leaves is discussed in the light of energy flow and nutrient cycling within seagrass systems.     

Mytilus edulis planulatus: an “integrator” of cadmium pollution?

Mussels, Mytilus edulis planulatus, were collected from Port Phillip Bay, Victoria, Australia, in February 1984, to test the assumption that they are integrators of cadmium pollution. Groups of mussels were subjected to the same average dose of cadmium (21 g l^-1), administered according to different dosing regimes over 4 wk (Regimes 1, 2, 3, 5); other groups received twice the average dose (42 g l^-1) in half the time (Regime 4). During each regime, the mussels were exposed to the different cadmium concentrations for one week at each concentration. Nominally, the regimes were: (1) 36 g (Wk 1) to 26 g (Wk 2) to 16 g (Wk 3) to 6 g (Wk 4) Cd l^-1; (2) 6 to 16 to 26 to 36 g Cd l^-1; (3) 21 to 21 to 21 to 21 g Cd l^-1; (4) 42 to 42 g Cd l^-1; (5) 42 to 42 g Cd l^-1 to background (<0.5 g) to background. Differences in cadmium accumulation by mussels from Regimes 1 and 4 were not statistically significant, nor were differences in accumulation between mussels from Regimes 2 and 3. However, mussels from Regimes 1 and 4 had accumulated significantly more cadmium than had mussels from Regimes 2 and 3. Accumulation by mussels from Regime 5 was not significantly different from that by mussels from any of the other regimes. These results suggest that, at least for cadmium, the assumption that mussels are integrators of pollution should be treated with caution. They also have implications with regard to the quantitative biological monitoring of pollution. For example, even in a carefully controlled monitoring program, using mussels of standard size and condition, significant differences in cadmium content between mussels need not indicate exposure to different levels of contamination. Rather, these differences could reflect differences in the regime by which the contamination was received.     

Use of signature whistles during separations and reunions by wild bottlenose dolphin mothers and infants

We examine the contexts and patterns of signature whistle production by wild bottlenose dolphin mother-infant pairs (Tursiops spp.) to gain insight into the functional significance of whistles. Results are based on focal observations and simultaneous recordings of underwater vocalizations. Whistles occur primarily when mother-infant pairs are separated, and the probability of whistles increases with distance of separation. The timing of whistles during separations varies, but whistles tend to be produced in repetitive series and are generally concentrated toward the later stages of the separation, i.e., during the process of reunion. Although we focused on infants, mothers do not appear to whistle during separations as frequently as infants. Infant whistles may function to facilitate reunions by conveying information to the mother concerning the infant's motivation to reunite and/or its location. Infant whistles could induce a cooperative response from the mother including approach, slowing to allow the infant to catch up or whistling. Highly individualized signature whistles may be particularly useful in a fission-fusion society in which individuals (mothers and infants as well as adults) join and leave temporary parties in a fluid manner, yet maintain consistent, long-term associations with particular individuals. Correspondence to: R.A. Smolker     

Modulation-assisted high speed machining of compacted graphite iron (CGI)

The application of controlled, low-frequency modulation (～100 Hz) superimposed onto the cutting process in the feed-direction – modulation-assisted machining (MAM) – is shown to be quite effective in reducing the wear of cubic boron nitride (CBN) tools when machining compacted graphite iron (CGI) at high machining speeds (>500 m/min). The tool life is at least 20 times greater than in conventional machining. This significant reduction in wear is a consequence of the multiple effects realized by MAM, including periodic disruption of the tool–workpiece contact, formation of discrete chips, enhanced fluid action and lower cutting temperatures. The propensity for thermochemical wear of CBN, the principal wear mode at high speeds in CGI machining, is thus reduced. The tool wear in MAM is also found to be smaller at the higher cutting speeds (730 m/min) tested. The feed-direction MAM appears feasible for implementation in industrial machining applications involving high speeds.     

Overcoming barriers to sustainability by combining conceptual,visual, and networking systems

Sustainability challenges rarely align with the conventional boundaries of our disciplines, institutions and means of communication. To address these challenges amid real-world complexity, we need to think holistically and collaborate across disciplines. In this paper, we synthesise three themes: (1) more integrated conceptual frameworks; (2) digital visual communication which provides fluid expression of complex ideas and perceptions; and (3) online networks which can empower sustainability initiatives and communicate them across social and institutional barriers at a global scale. Each of these tools can help to overcome persistent barriers to sustainability. When used together, they provide a strategic basis for the design of digital collaboration platforms for addressing sustainability challenges. Using design thinking, we developed a Synergy Map which identifies relationships among a number of barriers to sustainability and conceptual and digital tools which help to address them. The Map identifies the potential for synthesising these tools into effective digital artefacts. We provide several examples and identify characteristics of particular value for overcoming barriers to sustainability. Combining new theoretical developments in sustainability sciences with recent advances in communication and networking technologies offers substantial potential for advancing sustainability on multiple fronts.     

Temporal and geographical genetic variation in the amphipod Melita plumulosa (Crustacea: Melitidae): Link of a localized change in haplotype frequencies to a chemical spill

Anthropogenic effects such as contamination affect the genetic structure of populations. This study examined the temporal and geographical patterns of genetic diversity among populations of the benthic crustacean amphipod Melita plumulosa in the Parramatta River (Sydney, Australia), following an industrial chemical spill. The spill of an acrylate/methacrylate co-polymer in naphtha solvent occurred in July 2006. M. plumulosa were sampled temporally between December 2006 and November 2009 and spatially in November 2009. Genetic variation was examined at the mitochondrial cytochrome c oxidase subunit I locus. Notably, nucleotide diversity was low and Tajima’s D was significantly negative amongst amphipods collected immediately downstream from the spill for 10 months. We hypothesize that the spill had a significant localized effect on the genetic diversity of M. plumulosa. Alternate explanations include an alternate and unknown toxicant or a localized sampling bias. Future proposed studies will dissect these alternatives.