bluuebunny/crossref_metadata_2025 huggingface dataset:
Prognostic significance of lymph node metastasis and surgical margin status for distal cholangiocarcinoma
Authors: Murakami Yoshiaki , Uemura Kenichiro , Hayashidani Yasuo , Sudo Takeshi , Hashimoto Yasushi , Ohge Hiroki , Sueda Taijiro
Published: February 2007

Background and Objectives

Prognostic indicators for patients with distal cholangiocarcinoma have not been confirmed because of its rarity. The aim of this study was to identify useful prognostic factors in patients undergoing surgical resection for distal cholangiocarcinoma.

Methods

Charts of 43 patients with distal cholangiocarcinoma who underwent surgical resection were retrospectively reviewed. Pancreatoduodenectomy was performed in 35 patients, and segmental bile duct resection in 8. Potential clinicopathological prognostic factors were examined by univariate and multivariate survival analysis.

Results

Postoperative complications occurred after surgery in 19 patients (44%), but there was no mortality. Overall survival rates were 72%, 53%, and 44% for 1, 3, and 5 years, respectively (median survival time, 26.0 months). Univariate analysis found that older age, pathological pancreatic invasion, lymph node metastasis, perineural invasion, positive surgical margin, and TNM stages II and III were significant predictors of poor prognosis (P < 0.05). Furthermore, lymph node metastasis and positive surgical margin were found to be significant independent predictors of poor prognosis with a Cox proportional hazards regression model (P < 0.05).

Conclusions

These results suggest that lymph node metastasis and positive surgical margin as determined by surgical resection might be useful in predicting post‐surgical outcome in patients with distal cholangiocarcinoma. J. Surg. Oncol. 2007;95:207–212. © 2007 Wiley‐Liss, Inc.
The effect of seasonal flooding on the clay mineralogy of a soil series in the Volta Lake drawdown area, Ghana
Authors: Amatekpor J. K.
Published: February 2007

Four pedons of Arenic/Grossarenic Paleustalf (Denteso Series), in the Volta Lake drawdown area in Northern Ghana, were described and sampled just before seasonal floodings commenced in the area. After 5 years of periodic flooding the soils were re‐examined and sampled. Soil properties required for soil classification, including the clay mineralogy, of both the pre‐flooding and the post‐flooding samples were determined. One of the main objectives was to identify changes in soil properties which result from the periodic flooding.

X‐ray diffraction (XRD) indicated that before flooding the main clay minerals of the Denteso were kaolinite and smectite, and there were also some mica and quartz in the total clay fraction. Comparison of the pre‐flooding with the post‐flooding data revealed that practically all the smectite disappeared from all the three sampled pedons that were flooded for 5 to 20 weeks during each flood cycle, while the smectite persisted in the non‐flooded pedon. With the disappearance of the 2 : 1 lattice clays there occurred a considerable decrease in cation exchange capacity (CEC) and in base saturation of the flooded pedons ranging from 0.04 to 3.63 cmol kg −1. Also, there was an increase in pH by 0.4 to 1 unit in most horizons of the flooded pedons in spite of the general decrease in base saturation. These changes in CEC, base saturation and pH support the XRD evidence that the seasonal floodings caused pedochemical weathering of the smectite in this loamy sand soil at a very fast rate during the 5 year period and this had resulted in the lowering of the buffering capacity and a general impoverishment of the soil series.
Land degradation, stocking rates and conservation policies in the communal rangelands of Botswana and Zimbabwe
Authors: Abel N. O. J. , Blaikie P. M.
Published: February 2007

Communal rangeland management policies in Botswana and Zimbabwe are based on incorrect technical assumptions about the stability of semiarid rangeland, the nature of rangeland degradation, and the benefits of destocking. Consequently, inappropriate policies, stressing the need to destock and stabilise the rangelands, are pursued. Acknowledgement of the great instability but intrinsic resilience of rangeland would encourage the Governments to more favourably regard the opportunistic stocking strategies of the agro‐pastoralists of the Communal Areas. However, degradation of rangelands is occurring, although at varying rates. This justifies the promotion of a ‘tracking strategy’, in which livestock densities are encouraged to follow, more closely that at present, variations in rainfall.

The establishment of grazing territories controlled by specific ‘communities’ may be a prerequisite for the promotion of the tracking strategy, and for communal rangeland management and improvement. However, the establishment of such territories must take into account social equity, institutional problems and transaction costs, as well as spatial and temporal variation in rangeland resources.
Modelling soil organic matter decomposition and rainfall erosion in two tropical soils after forest clearing for permanent agriculture
Authors: Bouwman A. F.
Published: February 2007

A soil organic matter turnover model has been developed to analyse soil carbon (soil organic‐C) loss caused by organic matter decomposition and rainfall erosion in soils used for permanent cultivation. It has been used to build up model profiles of five soils, one occurring in temperate and four in tropical regions, on the basis of estimates for ‘natural’ organic matter input. Organic matter input data for different systems of cultivation were used to model the long‐term decomposition of soil organic‐C in these model profiles. The modelling results show that soil organic matter decomposition in the tropics is three to four times faster than in temperate regions, and that there is a marked influence of soil type and soil climate. Simulated losses of organic‐C in the tropical soils, not accounting for erosion are 31 to 50 per cent after 50 years and 43 to 63 per cent after 100 years of continuous cultivation. The simulated loss of soil organic‐C when rainfall erosion is also allowed for is 40 to 80 per cent. Erosion caused an extra loss of at least 7 per cent after 100 years. The initial input of charcoal from forest burning is lost through erosion at a rate of 50 to almost 100 per cent, depending on the severity of erosion. The sensitivity of modelling results to variations in input data was also analysed. The losses of soil carbon were also used to calculate the global flux of CO2 from soils. Soils are probably a small but not negligible source of CO2.
Quantification of accelerated soil erosion using the environmental tracer caesium‐137
Authors: Sutherland R. A.
Published: February 2007

The principal objective of this investigation was to quantify erosion rates for five agricultural fields in three separate study areas in Saskatchewan. The radionuclide tracer caesium‐137 (137Cs) was used to quantify net erosion and net deposition within the landscape over a 30‐year period. Uneroded (native) sites were used to establish the mean background level of 137Cs in each of the study areas. The assumption being that agricultural sites with 137Cs areal activities greater than the native site were subject to deposition, and sites with 137Cs less than the native control site were subject to erosion. A linear proportionality model was used to convert the loss or gain of 137Cs to net soil erosion or deposition. Results have indicated that accelerated (anthropogenic) erosion has been commonplace on arable land in Saskatchewan, even on near‐level fields (< 1.3 degrees). The net integrated sediment output from the five agricultural fields ranged from — 0.6 t th−1 y−1 to — 6.8 t ha−1 y−1 (where negative values represent erosion). What is more alarming is that between 40 and 75 per cent of all sites sampled within individual fields had erosion rates in excess of the generally accepted rate of soil formation (1.0 t ha−1 y−1). Also, in one highly eroded field (Crystal Springs medium sloping site) 65 per cent of the sites sampled exceeded the upper tolerable erosion rate of 11.0 t ha−1 y−1. These results indicate significant degradation of the non‐renewable soil resource has occurred over the past 30 years and is still presently active. Land degradation by accelerated erosion would result in reductions in effective rooting depth, soil moisture holding capacity, essential nutrient stores, and would adversely effect the physical structure of the topsoil. The major reason for accelerated erosion on arable land in Saskatchewan is the practice of summer fallowing, where the field is left in a ‘bare’ state and repeatedly tilled every second or third year. During a fallow period, or prior to crop emergence during a cropping year, fields are subject to wind and water erosion. On near‐level fields wind would be the dominant transport agent, while on sloping fields inter‐rill and rill erosion would be the primary forces of erosion. It is suggested that the appropriate conservation farming response would be to increase application of surface mulches and possibly to decrease the frequency of summer fallowing. Without such efforts long‐term sustainable agricultural production in the Prairies of Canada is considered to be a tenuous land use practice.
Development paths for rural areas in the european community
Authors: Conrad Jobst
Published: February 2007

Based on the findings from the research project: ‘Alternative Uses for Land and the New Farmworker—Segregation versus Integration’, this paper analyses broad lines of development and available options for rural areas in the European Community. Taking into account various limitations on agricultural, forestry, and nature conservation activities, the emergence of three agro‐structural regional types is likely to occur:

—rural areas with intensive agriculture;

—rural areas constituting mainly agrarian‐touristic peripheries, which exploit their endogenous development potentials on the basis of quasi‐tourism

—less‐favoured areas with a tendency towards depopulation, which may serve as ecological balance areas.
Preliminary evaluation of pineapple mixed‐cropping systems for protecting reclaimed gulleys in the tropics: An experiment in Southeast Nigeria
Authors: Asoegwu S. N. , Obiefuna J. C.
Published: February 2007

This paper reports on research into the effectiveness of pineapple monocropping or intercropping systems (with cowpeas or egusi‐melon) for reestablishing vegetative cover to check soil erosion on a reclaimed gulley in the tropical rainforest of southeastern Nigeria.

High‐density pineapple planting, intercropped with egusi‐melon, was found to promote rapid vegetative cover, checked soil loss, improved soil structural stability and produced a high crop yield. Soil loss was moderate in pineapple plots intercropped with cowpeas and least in pineapple plots intercropped with egusi‐melon. Increasing pineapple density enhanced the field establishment of cowpea and egusi‐melon respectively.
Avoidance of degradation of alpine pasture through grazing management: Investigations of change in vegetation nutrition characteristics as a consequence of sheep grazing at different periods of the growing season
Authors: Andrighetto I. , Cozzi G. , Zancan M. , Berzaghi P.
Published: February 2007

The maintenance of animal husbandry in mountain areas can prevent the general degradation of the landscape due to the disuse of pastures and meadows. This study investigated the changes over the productive season of the nutritional characteristics of an Alpine pasture with the objective of maintaining grazing sheep fed only on the available herbage.

Four homogeneous areas of an Alpine pasture located in northeast Italy were cut at the end of June, July, August, and September, simulating different grazing periods by the animals. the herbage was sampled to estimate the botanical and chemical composition and fed to four Lamon breed wethers (76‐5 kg average bodyweight) measuring voluntary intake, digestibility and energy value. the botanical composition of the pasture changed as the vegetative season advanced, with a progressive increase in grass species. the protein content decreased from 16‐3 per cent dry matter in the first grazing period, to 9‐6, 9‐9 and 7‐9 per cent, respectively, in the following, while the neutral detergent fibre increased from 62‐1 per cent in the first period to 78‐4, 77‐7 and 79‐4 per cent in July, August, and September, respectively.

The nutritional evaluation of the forage material was carried out using four Lamon wethers housed in single metabolic cages. the voluntary intake of herbage was 1151 g d−1 at the end of June, decreasing significantly to values below the recommended requirement for maintenance in the subsequent periods of the study. No selectivity was observed for specific botanical species. the in vivo digestibility of the herbage was lowered by the delay in the use of the pasture and the resulting energy intake met the recommended maintenance requirements for grazing only in the earlier period of pasture consumption. the late use of the pasture and the corresponding underfeeding of the animals would necessitate a feed supplementation to limit excessive loss of bodyweight. the conclusion is that the objective of maintaining grazing animals in mountain areas without any supplementation can be carried out exclusively by adopting an efficient grazing management able to provide good quality pasture throughout the vegetative season.
Environmental consequences of land degradation in coastal drainage basins of north Queensland, Australia: Influence of farming practices
Authors: Arakel A. V. , Loder T. , McConchie D. , Pailles C.
Published: February 2007

Views expressed by sugar cane farmers in the Johnstone Rivers system, north Queensland, are consistent with the broader community concern about the potentially adverse ecological effects of point source discharges to the Great Barrier Reef lagoon. the main link between agricultural land use and the deterioration of surface and groundwater quality in the region is perceived by the farmers to be a consequence of the influence exerted by new farm management strategies and economic constraints on local environmental variables, particularly soils. the effectiveness of the land use practices in relation to land capability and productivity thresholds is considered by farmers to be essential for developing new farm management strategies and for improving water quality in the north Queensland coastal regions. as a result of increasing inhomogeneity of land use practices involving the application of chemicals, catchment based investigation, including systematic interviews with the land users, is needed for the development of reliable databases on problems related to the discharge of agricultural chemicals to coastal waters.
Potential chemical time bombs in the schelde estuary
Authors: Van Eck G. T. M. , De Rooij N. M.
Published: February 2007

The Schelde estuary is heavily polluted with many different (micro)pollutants. This results in high concentrations in the abiotic and biotic compartments of the Schelde estuary and in various effects. the present day suboxic and anoxic conditions in the upper estuary are probably responsible for the high distribution coefficients for some trace metals in the lower Schelde estuary (Western Schelde). a future reduction in discharges with a high biological oxygen demand will therefore not only result in higher oxygen concentrations, but probably also in lower distribution coefficients for trace metals in the Western Schelde. Simulations show that lower trace metal distribution coefficients will probably result in higher concentrations of dissolved (bioavailable) trace metals, even with substantially reduced discharge rates, due to the desorption of trace metals from resuspended bottom sediments.
Dyke‐protected floodplains: A possible chemical time bomb?
Authors: Japenga J. , Salomons W.
Published: February 2007

For more than a century contaminated sediment has been deposited on the Rhine floodplains. Freshly deposited sediment samples from the regularly flooded dyke‐protected floodplain were obtained in 1958, 1970, 1972, 1981 and 1988. Heavy metals and arsenic as well as chemically persistent organic micropollutants [polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB) and DDT derivatives] were determined in the air‐dried samples stored in a specimen bank. Pollutant levels showed a tendency to decrease; for PCBs and HCB the highest levels were present in the 1970s. Concentrations exceed natural background levels and in some instances are well above alarm levels established for the Netherlands. Although a decrease has been seen in the average annual input of pollutants onto the floodplain, accumulation in the upper layer of the floodplain sediments continues. as a consequence of the general chemical characteristics of the sediment (high organic matter, calcium carbonate and clay contents) the pollutants remain tightly bound to the sediment particles. as the pollutant levels are high, changes which reduce the organic matter and calcium carbonate contents May, cause severe environmental problems: enhanced bioavailability and leaching of pollutants May, result from the increased solubilization of pollutants.
Local faces, global flows: The role of land use and land cover in global environmental change
Authors: Turner B. L.
Published: February 2007

The emergence of land‐use and land‐cover change (LUCC) as one of the major themes within the global environmental change research community poses a series of difficult but not insurmountable problems. LUCC takes place incrementally through the operation of sets of human and biophysical forces largely specific to the locale in question, but cumulatively LUCC contributes significantly to global environmental change. Linking LUCC to global change requires the cooperation of the natural and social sciences to bridge the local to global dynamics involved. The International Geosphere‐Biosphere Programme and the Human Dimensions of Global Environmental Change Programme are undertaking the development of an international research project with such aims in mind. This project seeks to improve understanding of LUCC dynamics by balancing the need for a nuanced understanding at the local level with the need from improved regional and global LUCC models. The rudiments of this effort and some of problems confronting it are outlined here.
Future of land use in Australia: An economic perspective
Authors: Mues C. , Peterson D. , Walshaw T. , Morris P.
Published: February 2007

It is proposed that the standard economist's model of optimum land use is extended to include the interaction with land cover and land condition. Such a model allows consideration of the influence of market factors and government policies and programmes on land use patterns and management practices, and the feedback effect on land cover and land condition. Recent developments in the approach to modelling land condition, which include the joint consideration of economic factors and physical processes, are discussed. Factors affecting the pattern of agricultural land use in Australia are then reviewed. The importance of considering economic and physical interactions when assessing land use patterns is increasingly being recognized in research and policy development. If research is to meet the needs of land managers in the future then economists and physical scientists will need to integrate their data modelling capabilities in order to address natural resource management issues.
Contribution of ‘sustainability’ criteria to social perceptions of land use options
Authors: Cocks K. D. , Walker B. H.
Published: February 2007

With relatively minor exceptions, the process of land use change is one of intensification and the narrowing of future land use options. This has led to community concern for the gradual irrecoverable loss of values associated with less intensive land uses; in particular, concern for the availability and functional capacity of biodiversity, earth materials, water and air. Concern extends to the functionality of these resources in industrial, amenity and service roles.

Such losses, called, inter alia, environmental costs, are never wholly avoidable despite the hopes behind the sustainable development concept. What is realistically possible is conservative development, meaning that land uses with environmental costs exceeding the economic net benefits would be proscribed as options, through the application of extant and emerging social technologies such as land use zoning, environmental standards and environmental impact assessment.

This paper presents some general and some more specific ideas about land uses susceptible to proscription under the conservative development criterion. Most major land uses stand to be challenged to a degree, particularly in densely populated areas, regions of economic opportunity and/or in regions recognized as having a high conservation value. Proposals involving a leap in intensification or loss of remnant or old‐established land uses will be more liable to assessment for proscription. Several regions are identified where joint assessment for exclusion across members of a suite of land uses would not be surprising (e.g. the Kimberleys); also some regions and situations where particular land uses stand to be challenged, e.g. irrigated cotton, high country developments and integrated forest harvesting.

Rather than list intensification trends at length and predict which challenges to intensification might succeed, this paper discusses the prospects for development of social technologies which evaluate community concerns about the environmental costs of land use intensification. It is suggested that a blending of the existing procedures of the Resource Assessment Commission for regional resource inventory and evaluation and the existing resource allocation procedures of the Great Barrier Reef Marine Park Authority would form a highly defensible core for a new generation of option‐defining technologies. The social importance of having a rich suite of social technologies for addressing intensification issues is emphasized.
Study of salinity and waterlogging in Uttar Pradesh (India) using remote sensing data
Authors: Dwivedi R. S.
Published: February 2007

Salinization/alkalization and waterlogging have rendered a sizeable area of India's arable lands unproductive. These highly dynamic phenomena can be studied using remote sensing data collected at regular intervals. Landsat Multi‐spectral Scanner data of 28 February 1975 and 9 March 1990 were interpreted visually to derive information about the spatial extent and distribution of salt‐affected soils. A significant decrease in the area of salt‐affected soils was noted over this period, which can be attributed to reclamation efforts by government agencies and farmers. On a large scale, i.e. 1:50000, the waterlogged area could also be mapped using a Landsat Thematic Mapper false‐colour composite print.
The effect of leaching and irrigation on the growth of Atriplex semibaccata
Authors: De Villiers A. J. , Van Rooyen M. W. , Theron G. K. , Claassens A. S.
Published: February 2007

Mining activities along the west coast of South Africa will lead to salinization of the soil if sea‐water is used in the mining process. Laboratory studies were conducted to determine the influence of leaching depth and the amount and frequency of irrigation on the growth of Atriplex semibaccata R. Br. Leaching depth as well as the amount and frequency of irrigation had no significant effect on biomass production. However, the interaction between leaching depth and amount of irrigation did influence the biomass production of Atriplex semibaccata. Root:shoot ratio increased as the amount of irrigation decreased.
Landscape changes as visible indicators in the social, economic and political process of soil erosion: A case study of the municipality of puebla de valles (Guadalajara Province), Spain
Authors: Garcia Perez J. D. , Charlton C. , Martin Ruiz P.
Published: February 2007

This paper proposes a methodological approach to data gathering as a sound basis for understanding land degradation processes, breaking down barriers of distrust between Government officials and land users, and promoting participation in planning for soil and water conservation. It examines how landscape changes, of value as indicators of erosion, are perceived by land users and can be used in planning. It is proposed that the participation of land users in the construction of questionnaires, data gathering, analysis and writing up of the findings are examples of the participatory initial stages in planning.
Land evaluation and conservation of semiarid agrosystems in Zaragoza (ne Spain) using an expert evaluation system and GIS
Authors: Machin J. , Navas A.
Published: February 2007

In the area around Zaragoza, agrosystems are very fragile. Water is the main limiting factor for cultivation. Annual rainfall does not exceed 350mm, and the occurrence of convective storms with short and intense periods of very heavy rainfall greatly increases the danger of water erosion. Also, the mostly squeletic soils in this sparsely vegetated area are prone to erosion. In this semiarid environment, soil essentially constitutes a non‐renewable resource, and therefore conservation of these agrosystems is an important issue and a serious environmental concern.

Effective land management and soil conservation strategies require a variety of information and maps. In this paper, an expert land evaluation system (MicroLEIS) along with a geographic information system (IDRISI) are used to develop a computerized spatial database in order to suggest suitable land management strategies for environment conservation.
Fast analysis of fats, oils and biodiesel by FT‐IR
Authors: Tseng Ching‐Hui , Wang Nan
Published: February 2007

Historically, the determination of chemical information or traits which describe the quality of fats and oils required analysis using wet chemistry, chromatography, and spectroscopic methods. Unfortunately, each of these methods is time‐consuming and requires a well equipped laboratory staffed with trained chemists. In contrast, Fourier Transform Infrared (FT‐IR) Spectroscopy is a fast analytical technique, but requires expertise for method development and operation. To overcome these difficulties, we have successfully developed a FT‐IR system which utilizes remote/local FT‐IR data collection, Internet communication to a central database, FT‐IR based chemometric analysis, and re‐communication of the analysis results to the remote unit. This Internet‐enabled quality trait analysis (QTA®) FT‐IR system has been thoroughly field tested. It has been found to be a rugged, fast, and accurate technique for the analysis of fats and oils and biodiesel. In addition, the Internet‐enabled QTA® FT‐IR system requires minimal skills for operation. Examples using the Internet‐enabled QTA® FT‐IR system for the analysis of fats and oils and biodiesel are described in this article.
Spin–spin coupling and substituent and halogen isotope shift effects in the fluorine NMR spectra of fluorinated cyclopropanes and cyclopropyl ethers
Authors: Brey Wallace S. , Richardson David , Bechtel Bethany , Aksenov Alexander
Published: February 2007

The 19F NMR spectra of a series of fluorinated cyclopropanes, most of which contain chlorine or bromine on the ring, have been observed and analyzed. A scheme has been developed to assign the resonances and the molecular stereochemistry, based on substituent effects, comparison of related molecules, and isotope shifts induced by the halogens. Replacement of fluorine by chlorine shifts cis fluorine resonances to lower field, and bromine has an even greater downfield influence. However, the shift effect of bromine compared to chlorine on gem or trans fluorines is variable. The magnitude of the isotope shifts is found to be regularly related to the geometrical relationship of the halogen to the observed fluorine and thus makes a significant contribution to the fluorine assignments. The three‐bond spin–spin coupling constants between fluorine atoms in cyclopropanes display unusual behavior and are not helpful for assignment of the fluorine resonances. The signs of the coupling constants have been investigated by spin‐tickling experiments, and the previously developed relation of the coupling constant sign to its temperature dependence has been found to be violated for some molecules. Copyright © 2007 John Wiley & Sons, Ltd.
A dual BIE approach for large‐scale modelling of 3‐D electrostatic problems with the fast multipole boundary element method
Authors: Liu Y. J. , Shen L.
Published: February 2007

A dual boundary integral equation (BIE) formulation is presented for the analysis of general 3‐D electrostatic problems, especially those involving thin structures. This dual BIE formulation uses a linear combination of the conventional BIE and hypersingular BIE on the entire boundary of a problem domain. Similar to crack problems in elasticity, the conventional BIE degenerates when the field outside a thin body is investigated, such as the electrostatic field around a thin conducting plate. The dual BIE formulation, however, does not degenerate in such cases. Most importantly, the dual BIE is found to have better conditioning for the equations using the boundary element method (BEM) compared with the conventional BIE, even for domains with regular shapes. Thus the dual BIE is well suited for implementation with the fast multipole BEM. The fast multipole BEM for the dual BIE formulation is developed based on an adaptive fast multiple approach for the conventional BIE. Several examples are studied with the fast multipole BEM code, including finite and infinite domain problems, bulky and thin plate structures, and simplified comb‐drive models having more than 440 thin beams with the total number of equations above 1.45 million and solved on a PC. The numerical results clearly demonstrate that the dual BIE is very effective in solving general 3‐D electrostatic problems, as well as special cases involving thin perfect conducting structures, and that the adaptive fast multipole BEM with the dual BIE formulation is very efficient and promising in solving large‐scale electrostatic problems. Copyright © 2007 John Wiley & Sons, Ltd.
Electrocatalytic reduction of alkyl iodides in tetrahydrofuran at silver electrodes
Authors: Paddon Christopher A. , Bhatti Farrah L. , Donohoe Timothy J. , Compton Richard G.
Published: February 2007

Recent interest in the electrocatalytic activity of silver towards the reduction of alkyl iodides has led us to investigate whether the effect is observed in tetrahydrofuran (THF) at room temperature. Using platinum electrodes in THF for the reduction of alkyl halides at 298 K has been hampered by the solvent window, which ‘obscures’ the voltammetric signals of interest. In order to overcome these problems, voltammetry has been performed at low temperature and was shown to extend the voltammetric window, leading to accurate electrochemical analyses and even novel changes in mechanism(s) of the reactive species following electron‐transfer (ET). Herein, it is shown that for a primary and tertiary alkyl iodide in THF, electroreduction at silver leads to a significant shift in the reduction potential to more positive values compared to platinum. In addition, following reduction, a characteristic series of oxidation peaks are observed and are shown to be due to the specific activity of iodide ions towards silver following reductive cleavage of the parent alkyl iodide. This characteristic feature is not observed with other halide ions: bromide and chloride. Preparative electrolyses at controlled‐potential have suggested that the reduction of the above alkyl iodides is a one‐electron concerted process. The ‘free’ iodide ions act as a monitor of reaction progression, and the carbon‐centred radical either dimerises and/or abstracts a hydrogen atom from the electrolyte/solvent; 1‐iodoadamantane giving percentage yields of 58% adamantane and 39% 1,1'‐biadamantane, the primary alkyl iodide, prepared in‐house, giving 67% R‐H and 25% R‐R. Copyright © 2007 John Wiley & Sons, Ltd.
Determinants of participation in social support groups for prostate cancer patients
Authors: Voerman Bert , Visser Adriaan , Fischer Maarten , Garssen Bert , van Andel George , Bensing Jozien
Published: February 2007

Objective: This study aims at determining factors related to the intention to participate and actual participation in social support groups for prostate cancer patients, using the framework of the theory of planned behavior. The factors studied are background variables, medical variables, psychosocial variables and attitude, social norms and perceived control.

Methods: From various sources, 238 prostate cancer patients were recruited. The patients filled out a questionnaire, containing standardized instruments on several psychosocial problems and social support, besides questions on demographic and medical characteristics. A specific questionnaire was developed to assess attitude, social norms and perceived control concerning the participation in support groups. From the recruited men, 48 participated in one of the support groups organized by the researchers.

Results: Logistic regression revealed that age, lack of social support, a positive attitude and a high perceive control are predictive for the intention to participate in a social support group. Perceived control and the number of prostate‐specific problems did predict the factual participation.

Conclusion: Many prostate cancer patients report psychosocial problems. A more positive attitude towards group participation and the availability of support groups at short travel distance facilitates the interest in and the factual group participation.

Practical implications: Urologist and urological nurses can play a role in creating a more positive attitude towards group participation, especially if the social support system is weak. Groups should be organized close to patients' place of residence. Copyright © 2007 John Wiley & Sons, Ltd.
Implications for palaeoenvironmental reconstruction of recent ice‐wedge development at Mayo, Yukon territory
Authors: Burn C. R.
Published: February 2007

Elevated tritium concentrations in ice veins and wedges recently exposed near Mayo, Yukon Territory, indicate that these features have formed or recracked from time to time during the past thirty years. The mean annual air temperature at Mayo is −4.0°C. Therefore, these features are active in an environment that conventionally would be regarded as too warm for thermal contraction cracking and ice‐wedge development. Periodic cracking is probably related to below‐normal winter air temperatures. Such conditions are not readily apparent in long‐term climatic statistics. It follows that many ice‐wedges whose casts are preserved in the geologic record may not have formed under conditions as cold as previously suggested.
Some observations on the growth and deformation of epigenetic, syngenetic and anti‐syngenetic ice wedges
Authors: Mackay J. Ross
Published: February 2007

Ice wedges are normally classified into two main types: epigenetic and syngenetic. Epigenetic wedges grow wider rather than higher or deeper. Syngenetic wedges grow both wider and higher more or less simultaneously with the deposition of material at the growth site. Field studies show that there is a third type, an anti‐syngenetic wedge, which grows downward on receding slopes in a direction normal to the slope. The downward growth rate is a function of the rate of ice‐veinlet growth and slope recession. The downward growth of an anti‐syngenetic wedge at a site with a net removal of material is thus opposite to that of the upward growth of a syngenetic wedge at a site with a net addition of material. The deformation of epigenetic, syngenetic and anti‐syngenetic wedges by shear and creep may complicate attempts at age‐dating the wedges by ice petrofabrics, stable isotopes and other methods.
Observations on buried glacier ice and massive segregated ice, western arctic coast, Canada
Authors: French H. M. , Harry D. G.
Published: February 2007

The two main theories for the origin of the thick bodies of massive ground ice known to exist in the Western Canadian Arctic are (1) segregation‐injection and (2) buried glacier ice. Because buried glacier ice may contain significant quantities of stratified debris and may have experienced thawing and refreezing (regelation) on several occasions, it may be very difficult to distinguish between massive segregated ice and buried basal glacier ice. By use of cryostratigraphic and cryotextural (petrofabric) observations, massive ground ice bodies observed in the Sandhills Moraine, southern Banks Island, and the southern Eskimo Lakes region, Pleistocene Mackenzie Delta, are both interpreted as basal glacier ice. Other massive ground ice bodies which have been examined in the Western Canadian Arctic are best explained in terms of segregation‐injection.
Permafrost and groundwater conditions, Huola river basin, northeast China
Authors: Wang Baolai
Published: February 2007

Permafrost and geohydrological investigations in a small basin in northeast China indicate that permafrost affects both the depth at which groundwater occurs and its artesian pressure. Artesian flow in the basin is common, and artesian head may be as much as 10 m above ground surface. The thickness of permafrost bears a close relationship to groundwater discharge (i.e. artesian flow rate), since a number of boreholes indicate that the greater the discharge, the thinner the permafrost. Over time the average rate of artesian flow from the boreholes decreases. The duration of flow depends on the rate of artesian flow, and permafrost temperature and thickness. Long‐term observations in areas where the permafrost is 70 m thick and has a mean annual ground temperature of −2.5°C indicate that if flow rate is larger than 0.8 l/s, flow continues for an indefinite period of time, but that if flow is less than 0.6 l/s, flow stops shortly. The difference in permafrost thickness, caused by the differential development of fractures and associated artesian head, may be as great as 50 m. Massive ground ice, with a thickness of more than 20 m, occurs in some boreholes at depth and is probably intrusive in nature.
Apparent hydraulic conductivities associated with thawing, frost‐susceptible soils
Authors: Egginton P. A. , Dyke L. D.
Published: February 2007

Horizontal permeameter tests indicate that the apparent hydraulic conductivity of a frost‐susceptible soil increases by one or more orders of magnitude as ice‐rich layers are encountered by an advancing thawing front. When thaw progresses into ice‐poor layers and the former ice‐rich layers consolidate, permeability decreases.

On arctic slopes it is postulated that if the water enters a given slope segment under excess hydraulic head, then consolidation of the thawing soil in that segment may be retarded for some period of time; as a result, macropores formed by thawing ice lenses may be maintained and horizontal permeabilities may be elevated relative to those that may be encountered once the soil has consolidated.
Drainage karstique en milieu de pergélisol: le cas de l'ǐle d'akpatok, T.N.O. Canada
Authors: Lauriol B. , Gray J. T.
Published: February 2007

L'ǐle étudiée, située au nord‐ouest de la baie d'Ungava, est formée de calcaires ordoviciens qui reposent en strates subhorizontales sur le socle archéen. Des observations sur le terrain et sur des photos‐aériennes ont révélé que le drainage souterrain est trés important, malgré le fait que la température moyenne annuelle d'environ −7 °C implique un pergélisol profond. L'eau issue de la fonte nivale printanière pénétre dans les fissures, et dans les dolines aux fonds des dépressions associèes aux lacs. Cette disparition des eaux de surface est plus rapide dans le secteur sud de l'ǐle, que dans le secteur nord. Une diminution de l'épaisseur du tapis nival vers le sud de l'ǐle est peutětre responsable en partie de ce contraste. Peu d'eau réapparait le long des falaises et au fond des vallées, ce qui laisse supposer la présence de sources sous‐marines. Des profils thermiques ont montré que le pergélisol est présent sur l'ǐle, mais qu'il est possiblement interrompu par des taliks associés aux pertes d'eaux verticales. Les analyses hydrochimiques ont fourni des résultats comparables à ceux des autres eaux des karsts arctiques: des duretès totales voisines de 100 mg/1 CaCo3. Un modèle de circulation d'eau souterraine en milieu de pergèlisol est proposé.
Periglacial phenomena in New Zealand
Authors: Soons J. M. , Price L. W.
Published: February 2007

The presence of periglacial phenomena and activity in New Zealand is controlled primarily by altitude, especially as modified by topography and lithology. Thus, the alpine‐type mountains that form the backbone of the South Island (Southern Alps) show little in the way of patterned ground, while the block mountains of Otago and less sharply peaked mountains in Canterbury and Marlborough display these features on varying scales. Some forms are considered to be fossil, while others are at present active. This paper reviews the distribution and character of periglacial phenomena in New Zealand, as well as the broad factors controlling their origin and development.
Late pleistocene ice‐wedge casts and sand‐wedge relics in the wyoming basins, USA
Authors: Nissen Thomas C. , Mears Brainerd
Published: February 2007

Previous studies of late Pleistocene periglacial wedge relics in the present‐day steppe environment of the Wyoming plains are supplemented by laboratory analyses of the wedge‐filling materials. Field observations of the wedges now allow the differentiation of ice‐wedge casts, sand‐wedge relics and composite types, as well as epigenetic, syngenetic and polygenetic forms. The wedges penetrate both bedrock and unconsolidated Pleistocene deposits. The poorly sorted clastic wedge‐fills contain secondary pedogenic clays, clasts from abutting host materials and arkosic silty sands derived from late Pleistocene aeolian surficial deposits. Quartz grains in the coarser fractions of the wedge‐fills are well‐rounded and wind‐abraded, reflecting aeolian transport. Quartz particles displaying distinctive conchoidally fractured surfaces become increasingly abundant in the finer sand fractions—a phenomenon attributed to in situ, cryogenic weathering at the microscopic level. The wedges indicate a windswept permafrost environment characterized by thin or minimal snow covers. The abundance of sites where wedges penetrate weathered bedrock is attributed to the ongoing episode of late Cenozoic regional erosion in Wyoming.
Temperature variation and apparent thermal diffusivity in the refreezing active layer, Toolik Lake, Alaska
Authors: Hinkel K. M. , Outcalt S. I. , Nelson F. E.
Published: February 2007

Temperatures were sampled at eight‐hour intervals over a five‐month period within the refreezing active layer at Toolik Lake, Alaska. The variance spectra of the temperature series, calculated as a function of wavelength, reveal relatively high‐frequency (sub‐diurnal) temperature fluctuations near the base of the active layer during refreezing, behaviour that is not consistent with a purely conductive system. The thermal records were also used in a numerical scheme to calculate apparent thermal diffusivity at regularly spaced depths in the substrate. Widely fluctuating positive and negative diffusivity values suggest that non‐conductive processes play an important role in heat transport during and after freezeback. Phase transformations, vapour diffusion and water advection all can enhance or oppose the conductive tendency. Models based exclusively on conductive principles are inadequate to explain thermal evolution in the dynamic near‐surface layer of permafrost regions.
Chronology of periglacial structures in Northern China
Authors: Jianzhong Sun
Published: February 2007

Structures of assumed periglacial significance in Northern China include (1) ice‐wedge casts, (2) frost cracks and (3) involutions. On the basis of involutions and palynological analyses, the earliest period of periglacial conditions (Nangou Periglacial Stage) occurred 2.5‐3.15 × 106 years BP. Ice‐wedge casts near Beijing indicate that permafrost extended at least that far south during the Taipingshan Periglacial Stage, dated at 900‐730 × 103 years BP. The most widely distributed periglacial structures relate to the Guxiangtun stage (36 000‐13 000 years BP), which can be broadly correlated with the last Glacial Stage. The most recent periglacial structures are involutions related to the Zhoulu (10000‐8500 years BP), Zhalainoer (5000‐3000 years BP) and Disaogouwan (≈ 2300 years BP) stages.
Present‐day periglacial activity in the Natal Drakensberg, Southern Africa: A Short Review
Authors: Boelhouwers J.
Published: February 2007

Active periglacial features are described for the Natal Drakensberg, a mountain region in southern Africa reaching up to 3482 m a.s.l. Surficial diurnal freezing is evident by features associated with needle ice activity, while thufa and micropatterned ground indicate more severe frost penetration. Solifluction phenomena are noted but have been insufficiently described as yet. Local environmental factors, such as aspect, moisture, topography, soil depth and texture, appear important in the regional distribution of periglacial features.

An altitudinal zonation of periglacial activity is tentatively linked to climatic thresholds but is inhibited by the influence of other environmental factors and a lack of climatic data. A marginal periglacial environment appears to prevail in the Drakensberg.
The evidence for cirque glaciation in Lesotho
Authors: Marker Margaret E
Published: February 2007

The cirque‐like hollows of the Lesotho high Plateau and its South African extension are a class of erosional landform attributed to processes active during Pleistocene cold phases. The hypothesis that these hollows are the product of glaciation is examined by a morphological analysis based on 12 parameters from a population of 628 hollows. Eight parameters were derived from map analysis. The survey extends over 156000 km2 between latitudes 28º30′ S and 30º00′ S. The data were considered by latitudinal belts subdivided into the Escarpment region and the Interior.

Most hollows are 800‐1000 m wide, almost circular and relatively shallow. Hollow distribution is related to plateau residuals on Drakensberg Formation basalt. Hollow frequency and density are greatest adjacent to the Great Escarpment between latitudes 29º S and 30º S and diminish westwards towards the Interior.

Indices of Flatness, as a means of differentiation between cirques of glacial and nival origin, were computed. Only 27% fall unequivocally into the glacial size class; a further 29% are intermediate in depth. The correlation of hollow frequency, density and morphological variability with areas of high present‐day precipitation and high altitudes support the hypothesis. The strong northern orientation and strong preference for hollows on the leeside of ridges aligned NW‐SE and E‐W is attributed to snow‐bearing southerly and southwesterly winds. This also supports the hypothesis. The conclusion is reached that weak cirque glaciation occurred on the high plateau at least once during the Pleistocene.
Thermal gradients and rock weathering at low temperatures: Some simulation data
Authors: Hall Kevin , Hall Alida
Published: February 2007

The heating of rock by insolation during subzero air temperatures may cause thermal stresses within that rock. The values of Δt may be such that fracturing due to thermal shock may occur. The uneven heating of a rock body may cause buttressing of the heated faces such that thermal stresses are accentuated. Upon removal of the heat source, rapid cooling may occur and values of Δt may be sufficient to cause thermal shock.

Replications of these thermal stresses may lead to fatigue and failure. The zone within which these stresses may occur is also one within which freeze‐thaw can take place if water is present. It is suggested that thermally induced fracturing of rock in cold environments may be a significant but underrated process. Thermal results of laboratory simulation experiments are presented during which values of Δt = >500ºC/h occurred for short periods.