The quality and qualities of population statistics, and the place of the census

Population counts are a key anchor for much of the official statistical system and the benchmark for many commercial and research surveys and analysis. Statistical offices around the world face a wide range of challenges in counting their population, most particularly in the years between censuses, as population flows become much freer and family structures continue to evolve. This paper considers these issues, reviewing how population counts have evolved over time in the UK and other countries. The paper also looks to the future, considering ways in which population count methodology might develop.     

Groundwater use by vegetation in a tropical savanna riparian zone (Daly River, Australia)

Soil water matric potentials (Ψ_m) and the deuterium (δ²H) composition at natural abundance levels of xylem water, soil water, river water and groundwater were used to evaluate whether trees use groundwater during the dry season in the riparian zone of the Daly River (Northern Territory, Australia). Groundwater was a significant source of water for plant transpiration, probably accounting for more than 50% of the water transpired during the dry season. Groundwater use occurred either when trees used water from the capillary fringe or when low Ψ_m induced by soil water uptake lifted groundwater in the vadose zone. Several water use strategies were inferred within the riparian plant community. Melaleuca argentea W. Fitzg and Barringtonia acutangula (L.) Gaertn. appeared to be obligate phreatophytes as they used groundwater almost exclusively and were associated with riverbanks and lower terraces with shallow (<5 m) water tables. Several species appeared to be facultative phreatophytes (including Cathorium umbellatum (Vahl.) Kosterm. and Acacia auriculiformis A. Cunn. ex Benth.) and tended to rely more heavily on soil water with increased elevation in the riparian zone. The levee-bound Corymbia bella K.D. Hill and L.A.S. Johnson mostly used soil water and is either a facultative phreatophyte or a non-phreatophyte. The temporal variability in groundwater utilisation by the trees is unclear because the study focused on the end of the dry season only. A decline in the regional water table as a result of groundwater pumping may affect the health of riparian zone vegetation in the Daly River because groundwater use is significant during the dry season.     

Present-day plate interactions in Northeast Asia: North American, Eurasian, and Okhotsk plates

Based on seismicity and focal mechanisms, a separate Okhotsk plate is identified which includes most of the Sea of Okhotsk, Kamchatka Peninsula, and the Suntar-Khayata Mountains, in the northeastern USSR. Using slip vectors from the largest earthquakes in the region, we obtain a North America-Eurasia pole of rotation near the Lena River delta and a Okhotsk-North America pole off western Chukotka. The computed poles satisfy observed thrust faulting mechanisms in the northern Cherskii Mountains which are discordant with models proposed by previous workers. It is suggested that the Arctic rift propagated through northeast Siberia to the Pacific, separating the Okhotsk plate and causing a recent (<3Ma) change in location of the North America-Eurasia pole of rotation.     

Reconstructed summer degree days in central Alaska and northwestern Canada since 1524

Three time series based on precisely dated annual tree-ring widths have been used to reconstruct June plus July degree days for the central Alaska and northwestern Canada region. The time series are the longest recently developed chronologies for the area and represent 57 core samples from 27 trees. The degree-day reconstruction, extending back to A.D. 1524, exhibits much year-to-year variation and extended warming and cooling trends including a general warming trend from about 1840 to 1960. The reconstruction is in agreement with some subaretic glacial information and with data of percentage melting from arctic ice cores. This and similar reconstructions can provide quantitative information to compare with general circulation and energy budget models for longer time periods than are available in recorded meteorological data.     

Towards an understanding of the southern Appalachian Piedmont crustal transition—A multidisciplinary approach

The Piedmont of the southern Appalachians is characterized by significant geophysical and geological anomalies which indicate there is a major crustal transition. Multiple hypotheses, including a suture zone and a subducted continental margin, have been presented to explain the variations. Although crustal seismic reflection data have provided significant constraints, there are ambiguities inherent in the interpretation of such data. The ambiguities can be reduced by careful consideration of related geophysical and geological observations. Although the importance of correlating crustal reflection data with known geologic features by tracing reflections to drill holes or to the surface cannot be overestimated, only rarely are such correlations possible. In almost all interpretations of crustal reflection structure it is necessary to constrain the model with methods such as seismic refraction, gravity, magnetics, conductivity, and surface geology (including palinspastic reconstructions). When information from these techniques is incorporated into interpretations of the Piedmont crustal structure, the model which appears to be most consistent with the observations is one in which the upper crust of the Piedmont is decoupled from the lower crust, and in which the lower crust thins eastward. The lower crust may be a subducted Precambrian continental margin and its associated transition toward thinner, basinal crust.     

Fluxes of gases and particles above a deciduous forest in wintertime

Eddy-correlation measurements of the vertical fluxes of ozone, carbon dioxide, fine particles with diameter near 0.1 m, and particulate sulfur, as well as of momentum, heat and water vapor, have been taken above a tall leafless deciduous forest in wintertime. During the experimental period of one week, ozone deposition velocities varied from about 0.1 cm s^–1 at night to more than 0.4 cm s^-1 during the daytime, with the largest variations associated primarily with changes in solar irradiation. Most of the ozone removal took place in the upper canopy. Carbon dioxide fluxes were directed upward due to respiration and exhibited a strong dependence on air temperature and solar heating. The fluxes were approximately zero at air temperatures less than 5 °C and approached 0.8 mg m^–2 s^–1 when temperatures exceeded 15 °C during the daytime. Fine-particle deposition rates were large at times, with deposition velocities near 0.8 cm s^–1 when turbulence levels were high, but fluxes directed upward were found above the canopy when the surface beneath was covered with snow. Diffusional processes seemed to dominate fine-particle transfer across quasilaminar layers and subsequent deposition to the upper canopy. Deposition velocities for particulate sulfur were highly variable and averaged to a value small in magnitude as compared to similar measurements taken previously over a pine forest in summer.     

Geography fieldwork in a 'risk society'

The recent decline in fieldwork provision in UK schools has partly been attributed to false perceptions of risk among teachers. This paper examines a case study based on geography teachers' perceptions from six state secondary schools in a northern English city. The research shows that owing to the inherent subjectivity of risk perception, these teachers' perceptions of fieldwork risk cannot be dismissed as false. Furthermore, it is argued that owing to the implicit, but powerful, spatialities of teachers' imaginations of fieldwork, these teachers will first need to re-evaluate the role and value of fieldwork before they are willing to re-enter the field.     

‘It’s more than just what it is’: Defetishising commodities, expanding fields, mobilising change…

Commodity geographies are politically weak. Geographical pedagogy isn’t particularly engaging. Radical geography should make connections. But it rarely leaves room for interpretation. Too much seems to be too didactic. And to preach to the converted. That’s a problem that needs attention. So, is it possible to develop a radical, less didactic, geography? With research funding, publication and teaching the way they are? To engage more students, more heartily, in the issues studied? To promote social justice, critical citizenship, and participatory democracy? But not by setting out the right ways to think, be, or act. Some film-makers, artists and writers have been able to do this. It seems. Subtly and cleverly. Through projects attempting to de-fetishise commodities. But their politics have been placed largely in the background, between the lines of, or separated out from, the presentation of scenes, things, relations, bodies, lives and voices. Seen and unseen elements of their audiences’ lives. Re-connected. Perhaps. Through communication strategies giving audiences something to think about and to think with, to argue about and to argue with. Putting themselves in the picture, in the process. These less didactic materials may be difficult to master for an exam or an essay. They may not make it clear who or what’s right or wrong or what audiences are supposed to do. But they could engage them in less direct ways. When they’re shopping for petrol or fish, or when they’re doing or thinking about completely different things. Things that may not even come under the heading of ‘production’ or ‘consumption’. This approach might be labelled as ‘weak’, ‘relativist’, a bit too ‘cultural’ ‘post-modern’, or ‘defunct’. But it’s an approach that may be radical in effect because its ‘politics’ aren’t so straightforward or ‘up front’. This paper is about changing relationships between research, writing, teaching, learning and assessment; expanding fields of commodity geographies to include classrooms as sites not only of ‘instruction’, but also of learning, for researchers and their students¹; showing how such learning might usefully shape research and writing elsewhere in these fields for those engaged in this defetishising project.     

Internal motions and the figures of planets

Summary. The problem discussed in this paper is the effect of specified internal motions upon the external figure of a rotating planet.
An equation for the perturbation of a surface of constant density is derived. The properties of motions which can be maintained in a gravitational field are established.