bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThis 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

AbstractIn 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

AbstractHistorically, 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

AbstractThe 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

AbstractA 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

AbstractRecent 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

AbstractObjective: 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

AbstractElevated 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

AbstractIce 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

AbstractThe 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

AbstractPermafrost 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

AbstractHorizontal 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

AbstractL'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

AbstractThe 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

AbstractPrevious 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

AbstractTemperatures 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

AbstractStructures 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

AbstractActive 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

AbstractThe 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.