Cyclones over Fram Strait: impact on sea ice and variability

The relation between sea ice drift and cyclone activity in the Fram Strait region was studied by both in situ observations and long-term time series. In a 1999 field campaign, the atmospheric forcing and the ice drift were determined using a research aircraft and drifting ice buoys. One cyclone entered the experimental area and caused a temporal increase in ice drift speed. Long-term studies are based on 16 years of cyclone statistics and model, satellite and sonar ice drift estimates. The actual impact of a cyclone depends on its particular track through Fram Strait. On the average, cyclones increase the Arctic ice export through Fram Strait.     

Ecology, shell morphology, anatomy and sperm ultrastructure of the caenogastropod Pyrgula annulata, with a discussion of the relationship between the ‘Pyrgulidae’ and Caspian and Baikalian Rissooideans

The composition of the Pyrgulidae and its relationships to other member families of the caenogastropod superfamily Rissooidea are examined after a consideration of new anatomical (including gross anatomy, sperm ultrastructure), conchological (including protoconch features), ecological, biogeographical and palaeontological data and a re-evaluation of existing literature. Pyrgulidae can be distinguished from hydrobiids unequivocally only with the aid of the radula. Sperm ultrastructural features suggest a very close relationship between the Pyrgulidae, the Hydrobiidae and the Bithyniidae (in fact no family-diagnostic sperm characters can be found to separate these three taxa). Based upon neontological and fossil evidence it is likely that pyrgulids represent a Miocene offshoot from a paratethyal hydrobiid lineage. Pyrgulids may also represent the stock from which the baicaliids arose, in which case the Pyrgulidae must be considered a paraphyletic group. The huge biogeographic gap between the Caspian Sea and Lake Baikal is to some extent bridged by the finding of a Neogene pyrgulid from the Altai Mountains. An alternative scenario for the origin of baicaliids is presented.     

Spatial Relationship between Dwelling Crowding and Selected Causes of Morbidity in Sydney,Australia, 1994–97

The environment in which we live greatly influences our health. One particular factor that has been related to morbidity and mortality is dwelling crowding. A range of mechanisms have been proposed as links between dwelling crowding and disease, including increased exposures to allergens, respiratory irritants and infectious agents in crowded dwellings. While studies of dwelling crowding have been conducted in many locations around the world, this factor has received little attention in Australian health studies. We examine relationships between dwelling crowding and health in Sydney, using three case studies at the local government area (LGA) level within the Sydney Statistical Division. Dwelling and demographic data from the 1996 Australian census are used, along with four socio-economic indexes produced by the Australian Bureau of Statistics, and hospital inpatient data for the period 1 July 1994 to 30 June 1997 as the health indicator. Results suggest that dwelling crowding is a significant factor in certain diseases in Sydney. Asthma hospital separations are not correlated with dwelling crowding, although multiple linear regression analysis produces three models which include crowding and three of the socio-economic indexes as significant variables. Separations for bronchitis and emphysema, and all causes combined, are positively correlated with dwelling crowding. Dwelling crowding is strongly negatively correlated with all but one of the socio-economic indicators.     

Damaging Weather Conditions in the United States: A Selection of Data Quality and Monitoring Issues

The limitations of observational data available for the study of damaging weather conditions (e.g., storms and extreme temperature events) are discussed. Crop and property insurance loss records are advocated as a potential supplement to traditional weather observations, as they integrate specific information about the spatial dimension of damaging weather conditions and the cost of damage they cause. Insurance loss data may also be analyzed in combination with meteorological data sets to derive indicator variables for the detection of damaging weather events.Two sets of insurance data are described. One record provides adjusted property losses associated with "catastrophic" weather events since 1949, and the other is an index of the amount of crop-hail losses per year since 1948. Additionally, an example of the benefits of the combination of insurance and meteorological data is presented through a selection of results from a recent study of freezing temperatures in the southeastern United States and associated insurance claims related to pipe bursting.If insurance data are to be applied in the future in similar studies of damaging weather conditions, it is essential that the insurance industry continues to collect and adjust loss data and periodically confirm that adjustment factors are temporally consistent.     

The Speciation of (CH3)2Sn2+ in Electrolyte Solution Containing the Major Components of Natural Waters

Hydrolysis constants of dimethyltin(IV) cation, in different salt solutions (CaCl₂: 0.15 I 0.90; MgCl₂: 0.30 I 0.60; NaCl-–NaClO₄, NaCl-–NaNO₃ mixtures: I = 3; NaCl-–Na₂SO₄ mixtures: I = 1 mol dm^-3) were determined by potentiometric ([H⁺]-glass electrode) measurements. These data, together with previous data (De Stefano et al., 1996b) were interpreted in terms of DHT (Debye–Hückel type) and Pitzer equations. The mixed electrolyte solution results also allowed us to obtain and parameters for the Pitzer equation. Calorimetric measurements were made at different ionic strengths in order to find the temperature dependence of hydrolysis constants and of the relative interaction parameters. The body of results allows us to determine the speciation of natural waters in a wide range of ionic strengths and temperatures.     

Grouped regression analysis—A sedimentologic example

When sample data are divided into groups, and observations consist of the independent variable xand associated dependent variable y,a logical form of analysis is “grouped regression.” This statistical technique allows testing of the relationship between the two variables and assessment of how the relationship is affected by the grouping. A sedimentologic example illustrates the usefulness of such a technique in classifying environments of deposition based on the size of quartz grains and the quartz content.     

Flow over an embankment: Speed-up and pressure perturbation

The speed-up of the flow over a small embankment is studied. Wind speed was measured in both the inner and outer layer of the flow. Hence, the height of the inner layer can be clearly identified in the measurements. The influence of stratification on the speed-up ratio is also investigated. Additionally, pressure was measured at six sites over the embankment. The results are compared with theoretical studies of Hoff (1987) and Sykes (1980). The perturbation pressure scales withu(l)u(L)H/L and not withu ² (L)H/L as assumed by Jackson and Hunt (1975).