bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of brassinosteroid responses by Phytochrome B in rice
Authors: JEONG DONG‐HOON , LEE SHINYOUNG , KIM SONG LIM , HWANG ILDOO , AN GYNHEUNG
Published: March 2007

Plant growth and development are coordinately controlled by environmental signals and internal factors. Light signals, mediated by phytochromes, regulate photomorphogenesis by interacting with endogenous programmes that involve multiple phytohormones. Brassinosteroids (BRs) are a group of growth‐promoting phytohormones with a crucial role in the light‐dependent development of plants. However, the interaction between light‐signalling pathways and BR signalling is not well understood. Here, we examined the responses of lamina joint inclination and coleoptile elongation to exogenous brassinolide (BL) under light or dark conditions. Both responses were more pronounced under darkness, implying that BR signalling is inhibited by light. To elucidate which phytochrome is involved in this interaction, we isolated rice phytochrome‐deficient mutants (osphyA, osphyB and osphyC) from a T‐DNA insertional population. Whereas the osphyA and osphyC knockout mutants did not differ from the wild‐type plants in their BL responses, osphyB mutants were more sensitive. In addition, RT‐PCR analysis revealed enhanced expression of BR‐inducible genes and decreased transcript levels of BR‐biosynthetic genes in osphyB plants. These results suggest that Phytochrome B acts as a negative regulator of BL‐regulated growth and development processes in rice.
Transcriptional profiling of hexaploid wheat (Triticum aestivum L.) roots identifies novel, dehydration‐responsive genes
Authors: MOHAMMADI MOHSEN , KAV NAT N. V. , DEYHOLOS MICHAEL K.
Published: March 2007

We used a long‐oligonucleotide microarray to identify transcripts that increased or decreased in abundance in roots of dehydration‐tolerant hexaploid bread wheat, in response to withholding of water. We observed that the major classes of dehydration‐responsive genes (e.g. osmoprotectants, compatible solutes, proteases, glycosyltransferases/hydrolases, signal transducers components, ion transporters) were generally similar to those observed previously in other species and osmotic stresses. More specifically, we highlighted increases in transcript expression for specific genes including those putatively related to the synthesis of asparagine, trehalose, oligopeptide transporters, metal‐binding proteins, the gamma‐aminobutyric acid (GABA) shunt and transcription factors. Conversely, we noted a decrease in transcript abundance for diverse classes of glutathione and sulphur‐related enzymes, specific amino acids, as well as MATE‐efflux carrier proteins. From these data, we identified a novel, dehydration‐induced putative AP2/ERF transcription factor, which we predict to function as a transcriptional repressor. We also identified a dehydration‐induced ‘little protein’ (LitP; predicted mass: 8 kDa) that is highly conserved across spermatophytes. Using qRT‐PCR, we compared the expression patterns of selected genes between two related wheat genotypes that differed in their susceptibility to dehydration, and confirmed that these novel genes were highly inducible by water limitation in both genotypes, although the magnitude of induction differed.
The relationship between isoprene emission rate and dark respiration rate in white poplar (Populus alba L.) leaves
Authors: LORETO FRANCESCO , CENTRITTO MAURO , BARTA CSENGELE , CALFAPIETRA CARLO , FARES SILVANO , MONSON RUSSELL K.
Published: March 2007

In past studies, it was hypothesized that reductions in chloroplast isoprene emissions at high atmospheric CO2 concentrations were caused by competition between cytosolic and mitochondrial processes for the same substrate, possibly phosphoenolpyruvate (PEP). We conducted field and laboratory experiments using leaves of white poplar (Populus alba L.) to identify whether an inverse relationship occurs between the dark respiration rate (a mitochondrial process) and the isoprene emission rate. Field experiments that were carried out in a free‐air CO2‐enriched (FACE) facility showed no clear effect of elevated CO2 on either isoprene emission rate or respiration rate by leaves. In young, not yet fully expanded leaves, low isoprene emission and high dark respiration rates were measured in both ambient and elevated CO2. In these leaves, isoprene emission was inversely correlated with dark respiration. It is possible to interpret from these results that, in young leaves, high rates of growth respiration compete with isoprene biosynthesis for the same substrate. However, it is also possible that the negative correlation reflects the contrasting reductions in growth respiration and increases in expression of the enzyme isoprene synthase at this final stage of leaf maturation. In contrast to our observations on young leaves, respiration rate and isoprene emission rate were positively correlated in older, fully expanded leaves (8 and 11 from apex). A positive correlation was also found between respiration rate and isoprene emission rate when these parameters were modulated using different ozone exposure, growth light intensity, growth temperature and exposure to different leaf temperatures in laboratory experiments. These data show that competition for substrate between isoprene biosynthesis and leaf respiration does not determine the rate of isoprene emission in most circumstances that affect both processes. A negative correlation was observed across all experiments between isoprene emission rate and the activity of phosphoenolpyruvate carboxylase (PEPc), a cytosolic enzyme that competes with isoprene biosynthesis for substrate. The cytosolic metabolite, PEP, occurs at a metabolic branch point from which substrate flows into three processes: (1) the production of pyruvate for mitochondrial respiration, (2) the production of oxaloacetate (OAA) by PEPc for anabolic support of mitochondrial respiration and (3) transport into the chloroplast to support chloroplastic demands for pyruvate, including isoprenoid biosynthesis. The results of our observations suggest that only the second process competes for substrate with isoprenoid synthesis, while the partitioning of PEP between mitochondrial respiration and chloroplast isoprenoid biosynthesis is controlled in a way that retains balance in substrate demand.
Measurement of stem respiration of sycamore (Platanus occidentalis L.) trees involves internal and external fluxes of CO2 and possible transport of CO2 from roots
Authors: TESKEY R. O. , MCGUIRE M. A.
Published: March 2007

CO2 released by respiring cells in tree stems can either diffuse to the atmosphere or dissolve in xylem sap. In this study, the internal and external fluxes of CO2 released from respiring stems of five sycamore (Platanus occidentalis L.) trees were calculated. Mean rates of stem respiration were highest in mid‐afternoon and lowest at night, and were positively correlated with air temperature. Over a 24 h period, on average 34% of the CO2 released by respiring cells in the measured stem segment remained within the tree. CO2 efflux to the atmosphere consisted of similar proportions of CO2 derived from local respiring cells (55%) and CO2 that had been transported in the xylem (45%), indicating that CO2 efflux does not accurately estimate respiration. A portion of the efflux of transported CO2 appeared to have originated in the root system. A modification of the method for calculating stem respiration based on internal and external fluxes of CO2 was developed to separate efflux due to local respiration from efflux of transported CO2.
Impacts of tree height on leaf hydraulic architecture and stomatal control in Douglas‐fir
Authors: WOODRUFF DAVID R. , MCCULLOH KATHERINE A. , WARREN JEFFREY M. , MEINZER FREDERICK C. , LACHENBRUCH BARBARA
Published: March 2007

This study investigated the mechanisms involved in the regulation of stomatal closure in Douglas‐fir and evaluated the potential impact of compensatory adjustments in response to increasing tree height upon these mechanisms. In the laboratory, we measured leaf hydraulic conductance (Kleaf) as leaf water potential (Ψl) declined for comparison with in situ diurnal patterns of stomatal conductance (gs) and Ψl in Douglas‐fir across a height gradient, allowing us to infer linkages between diurnal changes in Kleaf and gs. A recently developed timed rehydration technique was used in conjunction with data from pressure–volume curves to develop hydraulic vulnerability curves for needles attached to small twigs. Laboratory‐measured Kleaf declined with increasing leaf water stress and was substantially reduced at Ψl values of −1.34, −1.45, −1.56 and −1.92 MPa for foliage sampled at mean heights of approximately 20, 35, 44 and 55 m, respectively. In situ gs measurements showed that stomatal closure was initiated at Ψl values of −1.21, −1.36, −1.74 and −1.86 MPa along the height gradient, which was highly correlated with Ψl values at loss of Kleaf. Cryogenic scanning electron microscopy (SEM) images showed that relative abundances of embolized tracheids in the central vein increased with increasing leaf water stress. Leaf embolism appeared to be coupled to changes in gs and might perform a vital function in stomatal regulation of plant water status and water transport in conifers. The observed trends in gs and Kleaf in response to changes in Ψl along a height gradient suggest that the foliage at the tops of tall trees is capable of maintaining stomatal conductance at more negative Ψl. This adaptation may allow taller trees to continue to photosynthesize during periods of greater water stress.
Thellungiella: an Arabidopsis‐related model plant adapted to cold temperatures
Authors: GRIFFITH MARILYN , TIMONIN MARY , WONG ANNIE C. E. , GRAY GORDON R. , AKHTER SAJJAD R. , SALDANHA MARSHA , ROGERS MICHAEL A. , WERETILNYK ELIZABETH A. , MOFFATT BARBARA
Published: March 2007

Thellungiella salsuginea, a wild crucifer that grows in subarctic Canada and is closely related to Arabidopsis thaliana, was examined for its suitability as a model plant for studies of tolerance to cold and freezing temperatures. Thellungiella completed its life cycle at 5 °C, demonstrating that temperature‐sensitive processes such as seed germination and the production of pollen and seeds were resistant to cold temperatures. Moreover, the plant exhibited dramatically different vegetative and flowering phenotypes in response to growth at cold temperature and shifts to cold temperature. Northern analyses showed that genes induced by cold in Arabidopsis, including CBF1, the transcriptional activator for the cold‐regulated (COR) genes COR15a and COR47, were also expressed in Thellungiella. Freezing tolerance, assayed by the regrowth of intact plants, increased from −13.0 to −18.5 °C after cold treatment. The plants lacked endogenous ice nucleation or anti‐freeze activity, indicating a potential for supercooling. As a close relative to Arabidopsis, Thellungiella exhibits extreme cold tolerance and should be an important model system in the elucidation of stress tolerance mechanisms.
Kaposi's sarcoma in Nigeria
Authors: Onunu Abel N. , Okoduwa Cynthia , Eze Emeka U. , Adeyekun Ademola A. , Kubeyinje Emmanuel P. , Schwartz Robert A.
Published: March 2007

Background  The prevalence of Kaposi's sarcoma (KS) in parts of Africa has been on the increase as a result of the human immunodeficiency virus (HIV) infection pandemic. However, there is a paucity of information for Nigeria.

Objective  To describe the clinical and epidemiological characteristics of cutaneous KS in patients with HIV‐infection in Benin City, Nigeria.

Methods  All patients presenting to the dermatology and infectious diseases clinics of the University of Benin Teaching Hospital, or admitted to its medical wards, within the period July 2000–June 2005 were examined retrospectively in a chart review for KS. Diagnosis of HIV was based upon ELISA testing. The CD4+ cell counts were performed using the Dyna Bead method and KS was diagnosed histologically.

Results  In our survey, 31 patients, representing 0.84% of all new HIV patients seen during the study period, had cutaneous KS. There were 19 males and 12 females, giving a male to female ratio of 1.6 : 1. The mean age was 36.3 ± 9 years; mean CD4+ count was 127 ± 14  cells/dl. The lower limbs (74.2%), trunk (48.4%) and the face (22.6%) were the most frequent sites affected. The lesions were solitary in three patients (9.7%) and multiple in 28 patients (90.3%).

Conclusion  The prevalence of HIV‐related KS is increasing in Nigeria. There is an increase in the number of women being diagnosed with this form of KS, probably owing to more females having HIV disease.
A Ca2+ binding cyclic peptide derived from the α‐subunit of LFA‐1: inhibitor of ICAM‐1 /LFA‐1‐mediated T‐cell adhesion
Authors: Jois S. D. S. , Siahaan T. J. , Tibbetts S. A. , Chan M. A. , Benedict S. H.
Published: March 2007

The objective of this work is to study the conformation of cyclic peptide (1), cyclo (1, 12) Pen1‐Gly2‐Val3‐Asp4‐Val5‐Asp6‐Gln7‐Asp8‐Gly9‐Glu10‐Thr11‐Cys12, in the presence and absence of calcium. Cyclic peptide 1 is derived from the divalent cation binding sequence of the α‐subunit of LFA‐1. This peptide has been shown to inhibit ICAM‐1‐LFA‐1 mediated T‐cell adhesion. In order to understand the structural requirements for this biologically active peptide, its solution structure was studied by nuclear magnetic resonance (NMR), circular dichroism (CD) and molecular dynamics simulations. This cyclic peptide exhibits two types of possible conformations in solution. Structure I is a loop‐turn‐loop type of structure, which is suitable to bind cations such as EF hand proteins. Structure II is a more extended structure with β‐hairpin bend at Asp4‐Val5‐Asp6‐Gln7. There is evidence that alterations in the conformation of LFA‐1 upon binding to divalent cations cause LFA‐1 to bind to ICAM‐1. To understand this mechanism, the cation‐binding properties of the peptide were studied by CD and NMR. CD studies indicated that the peptide binds to calcium and forms a 1: 1 (peptide: calcium) complex at low calcium concentrations and multiple types of complexes at higher cation concentrations. NMR studies indicated that the conformation of the peptide is not significantly altered upon binding to calcium. The peptide can inhibit T‐cell adhesion by directly binding to ICAM‐1 or by disrupting the interaction of the α and β‐subunits of LFA‐1 protein. This study will help us to understand the mechanism(s) of action of this peptide and will improve our ability to design a better inhibitor of T‐cell adhesion.
Effects of temperature on the growth of spring ephemerals: Crocus vernus
Authors: Badri Mohamed A. , Minchin Peter E. H. , Lapointe Line
Published: March 2007

Spring ephemerals of deciduous forests appear shortly after snow melt and senesce shortly after the overstorey canopy has closed. During this short period, they take advantage of the high light conditions, but also of the low‐temperature regime that favours growth in these species. This better growth at cooler temperatures has been attributed to longer leaf life duration. The objective of this study was to test if temperature effect on growth in spring ephemerals can be explained solely by the leaf life duration, or if there is also a direct temperature effect on the underground organ growth. Crocus vernus (L.) Hill was exposed to two temperature regimes, 12/8 and 18/14°C (day/night), for sequential harvests and to four differential air to soil temperature regimes: 12/12, 12/18, 18/12 and 18/18°C (air/soil temperature). Dry mass, leaf nitrogen, starch concentration and cell size of the new corm were determined. Final dry mass and cell size were higher at the lower temperature regime while leaf lasted longer than at the higher temperature regime. Although both air and soil temperatures had an impact on the different growth parameters measured, the impact of soil temperatures was greater and it also influenced leaf life duration. At higher temperature, corm growth stopped before the first visual sign of leaf senescence, suggesting that corm growth controls leaf life duration in C. vernus rather than the opposite and that crocus growth becomes rapidly sink limited at higher temperatures.
Balance module allows consistent monitoring and documentation of the pooling process for nucleic acid amplification technology testing
Authors: Hourfar M. K. , Koller M. , Roth W. K. , Kehrli R. , Seifried E. , Schmidt M.
Published: March 2007

Background and Aims  When performing minipool testing of blood donations for transfusion‐transmissible viruses, it is crucial to correctly dispense plasma from each donation into the pools. However, concerns regarding the monitoring and documentation of the pooling process exist.

Methods  A balance module with a tube holder has been developed, which can be easily integrated into liquid handling platforms. The existing software monitors and evaluates every single dispensing from primary samples to the minipool to confirm liquid arrival. The weighing accuracy of the balance module is approximately 2 mg per dispensing episode.

Results  Ten thousand one hundred and fifty‐six blood donations were tested on a Tecan Genesis RSP‘ pipetting system. Thirty‐one donations were not pipetted because the pipetting workstation identified a clot or sample shortage in the primary tube. The balance module exclusively detected another 18 mispipettings, which were outside of the acceptance criteria of 100 ± 10%. The mean pipetted volume for these samples was 34.2 µl (range 0–87 µl). Visual inspection of the corresponding primary tubes showed blood clots, short sample or no apparent cause. The average deceleration of the pooling process, using the balance, was determined to be about 22%.

Conclusions  With the novel liquid arrival check system, complete and consistent process documentation of pooling for nucleic acid amplification technology (NAT) testing is feasible. It enables blood banks to monitor and compare every single dispense made with predefined, required volumes. Results can be transferred to the laboratory information management system for automated selective exclusion of inaccurately dispensed samples.

One sentence summary   Monitoring and documenting the pooling process for NAT testing using a balance‐based liquid arrival check system.
Experimental evidence of habitat provision by aggregations of Riftia pachyptila at hydrothermal vents on the East Pacific Rise
Authors: Govenar Breea , Fisher Charles R.
Published: March 2007

Habitat created or modified by the physical architecture of large or spatially dominant species plays an important role in structuring communities in a variety of terrestrial, aquatic, and marine habitats. At hydrothermal vents, the giant tubeworm Riftia pachyptila forms large and dense aggregations in a spatially and temporally variable environment. The density and diversity of smaller invertebrates is higher in association with aggregations of R. pachyptila than on the surrounding basalt rock seafloor. Artificial substrata designed to mimic R. pachyptila aggregations were deployed along a gradient of productivity to test the hypothesis that high local species diversity is maintained by the provision of complex physical structure in areas of diffuse hydrothermal flow. After 1 year, species assemblages were compared among artificial aggregations in low‐, intermediate‐, and high‐productivity zones and compared to natural aggregations of R. pachyptila from the same site. Hydrothermal vent fauna colonized every artificial aggregation, and both epifaunal density and species richness were highest in areas of high chemosynthetic primary production. The species richness was also similar between natural aggregations of R. pachyptila and artificial aggregations in intermediate‐ and high‐productivity zones, suggesting that complex physical structure alone can support local species diversity in areas of chemosynthetic primary production. Differences in the community composition between natural and artificial aggregations reflect the variability in microhabitat conditions and biological interactions associated with hydrothermal fluid flux at low‐temperature hydrothermal vents. Moreover, these local ecological factors may further contribute to the maintenance of regional species diversity in hydrothermal vent communities on the East Pacific Rise.
Biocontrol efficacy of Colletotrichum truncatum for hemp sesbania (Sesbania exaltata) is enhanced with unrefined corn oil and surfactant
Authors: BOYETTE C. DOUGLAS , HOAGLAND ROBERT E. , WEAVER MARK A.
Published: March 2007

In greenhouse and field experiments, an oil‐in‐water emulsion of unrefined corn oil and Silwet L‐77 increased the biological weed control efficacy of Colletotrichum truncatum (Schw.) Andrus et Moore for control of the weed, hemp sesbania (Sesbania exaltata[Raf.] Rydb. ex A.W. Hill). The surfactant – corn oil emulsion stimulated germination and appressoria formation in vivo and in vitro and delayed the need for dew. We hypothesize that the corn oil protected the conidia from desiccation during the dew‐free period and the surfactant stimulated spore germination and appressoria formation. In field experiments conducted over 3 years, a single application of a 50% (v/v) unrefined corn oil tank mixture containing 0.2% (v/v) Silwet L‐77 surfactant controlled hemp sesbania in soybeans an average of 95%. Aqueous fungal suspensions or adjuvants alone did not visually affect or control hemp sesbania. The soybean yields were significantly higher in the plots where weeds were effectively controlled. These results suggest that formulating C. truncatum in unrefined corn oil and surfactant greatly increases its infectivity and the biocontrol potential of this pathogen.
On the experimental evolution of specialization and diversity in heterogeneous environments
Authors: Jasmin Jean‐Nicolas , Kassen Rees
Published: March 2007

Environmental variance can be decomposed into two components: the contrast among patches in the optimal phenotype and the variance in productivity among patches. Both components can influence the outcome of selection in heterogeneous environments. In general genetic diversity within a population should increase as the contrast among patches increases. As the variance in productivity increases, on the other hand, individual niche breadth should decrease since the response to selection becomes dominated by adaptation to the most productive patch. We tested this interpretation of diversity in heterogeneous environments by selecting the bacterium Pseudomonas fluorescens over several hundred generations in pair‐wise mixtures of four carbon substrates. We then assessed the response to selection in the mixtures in terms of performance on each component substrate. The results provide general support for this interpretation of the environmental variance and suggest further that competition among genotypes promotes diversification in heterogeneous environments.
Plasticity in metabolic allometry: the role of dietary stoichiometry
Authors: Jeyasingh Punidan D.
Published: March 2007

Metabolism involves multiple elements. While we know much about the allometry in metabolic response of organisms to energy (carbon, C) availability, little is known about how different‐sized organisms respond to the relative availability of elements. I experimentally manipulated availability of phosphorus (P) relative to C, to test whether dietary C : P affects metabolism in four species of Daphnia, spanning an order of magnitude in body mass. Results indicated that the slope of the relationship between individual respiration and body mass was M0.83 under a balanced diet (C : P c. 150), and M0.67 under an imbalanced diet (C : P c. 800). Increased respiration under dietary imbalance was not due to increased ingestion. The change in the scaling exponent was due to the greater respiratory response of smaller species to altered diets. Diet‐induced metabolic plasticity contributes to variation in metabolic allometry, at least at such small scales of body size.
Escape in space from enemies: a comparison between stands with and without enhanced densities of the spruce bark beetle
Authors: Schroeder Leif Martin
Published: March 2007

1 Populations of the spruce bark beetle, Ips typographus (L.), are known to grow rapidly in storm‐disturbed stands as a result of relaxation from intraspecific competition. In the present study, it was tested whether a second mechanism, escape in space from natural enemies, also contributes to the rapid population increase.

2 The experiment was conducted during the initiation phase of five local outbreaks of I. typographus triggered by a storm‐disturbance in November 1995 in southern Sweden.

3 The impact of natural enemies on the ratio of increase (number of daughters per mother) of I. typographus was compared pairwise between disturbed stands with high numbers of storm‐felled trees and undisturbed stands without wind‐felled trees.

4 Enemy impact was assessed by comparing the ratio of increase in uncaged (exposed to enemies) and caged (protected from enemies) bolts colonized by I. typographus prior to being placed in the stands. The experiment was conducted in the second and third summers after the storm‐felling.

5 Enemy impact was about twice as high in stands without wind‐felled trees compared with in stands with wind‐felled trees in the second summer whereas there was no significant difference between the stand types in the third summer.

6 The result demonstrates that spatial escape from enemies contributes to the rapid population growth of I. typographus after storm‐disturbances.
TOPO TA is A‐OK: a test of phylogenetic bias in fungal environmental clone library construction
Authors: Taylor D. Lee , Herriott Ian C. , Long James , O'Neill Keith
Published: March 2007

TA cloning methods are widely used in analyses of environmental microbial diversity, yet the potential of TA methods to yield phylogenetically biased results has received little attention. To test for a TA bias, we constructed clone libraries of fungal amplicons spanning the ribosomal internally transcribed spacer (ITS) and partial large subunit (LSU) from 92 boreal forest soil DNA extracts using two contrasting methods: the Invitrogen TOPO‐TA system and the Lucigen PCR‐SMART system. The Lucigen system utilizes blunt‐ended rather than TA cloning and transcription terminators to reduce biases due to toxicity of expressed inserts. We analysed 588 clone sequences from the two libraries. Species diversity estimators applied to operational taxonomical units (OTUs) were slightly higher for Invitrogen than Lucigen, but confidence intervals for accumulation curves overlapped. Abundances of OTUs were correlated between the libraries (r2 = 0.5, P < 0.0001), but certain OTUs had contrasting abundances in the two libraries and a likelihood ratio test rejected homogeneity of the OTU counts. We constructed parsimony and Bayesian trees from aligned LSU regions, and the ‘phylogenetic test’ revealed that lineage representation was not significantly different between the two libraries. We conclude that characterization of this fungal community was fairly robust to cloning method and no biases due to TA cloning were found.
Conflict, trade and the medium‐term future of food security in Sudan
Authors: Keen David , Lee Vivian
Published: March 2007

Recent economic growth and the Comprehensive Peace Agreement (CPA) have both been seen as grounds for optimism about the future of food security in Sudan. However, solving the North‐ South conflict (if indeed it is solved) does not resolve conflicts within either the North or the South and may even encourage a variety of conflicts. The classic neoliberal prescription of peace, growth and foreign investment may deepen (and obscure) the needs and grievances of those who have historically been left behind in a dysfunctional development process. Historically, some of those marginalised by patterns of development in Sudan have chosen to rebel, while others have had their grievances diverted against those even more marginal than themselves. Dysfunctional and violent processes of development must be reversed. They cannot be adequately compensated for‐but may be legitimised‐by attempts to use food aid as a ‘safety net’. Meanwhile, those who benefited from war may have incentives to derail the peace.
Communicating uncertainty in spatial databases
Authors: HUNTER GARY J , GOODCHILD MICHAEL F
Published: March 2007

As applications of spatial databases become more sophisticated and diverse, an issue of growing concern is the inability to communicate to users the uncertainty of products derived from their systems. This is important not only because users should be able to compare the quality of database outputs against the quality requirements of their tasks (in order to determine product suitability), but also to protect the integrity of past, present, and future decisions that may be made through the use of such information. While there has already been considerable research undertaken to develop models of spatial data error and uncertainty, there is an additional requirement for the results of these models to be effectively conveyed to users. This paper reviews advances now being made in communicating the uncertainty of spatial databases which may soon assist users in overcoming this critical barrier.
Integrating dynamic environmental models in GIS: The development of a Dynamic Modelling language
Authors: WESSELUNG CEES G , KARSSENBERG DERC‐JAN , BURROUGH PETER A , VAN DEURSEN WILLEM P A
Published: March 2007

An integrated, executable mathematical modelling language for environmental and ecological applications has been developed to create and run Dynamic Models in a GIS. The modelling language is embedded in the GIS, providing the ability to model complex space‐time systems free from the technical burdens of database management and algorithm optimization. The spatial modelling language uses a structured script, which is illustrated here by an example of a model of plant dispersion.
A GIS for hydrological modelling in the semi‐arid, HAPEX‐Sahel experiment area of Niger, Africa
Authors: DESCONNETS J C , VIEUX B E , CAPPELAERE B , DELCLAUX F
Published: March 2007

During the HAPEX‐Sahel experiment (1991–94), water redistribution processes were studied at the meso‐scale (10 000 km2) near Niamey, Niger. A project now under way at ORSTOM aims at modelling the regional water balance through a spatial approach combining GIS data organization and distributed hydrological modelling. The main objective is to extend the surface water balance, by now available only on a few, small (around 1 km2) unconnected endoreic catchments, to a more significant part of the HAPEX‐Sahel square degree, a 1500 km2 region called SSZ that includes most of the environmental and hydrology measurement sites. GIS architecture and model design consistently consider data and processes at the local, catchment scale, and at the regional scale. The GIS includes spatial and temporal hydrological data (rainfall, surface runoff, ground water), thematic maps (topography, soil, geomorphology, vegetation) and multi‐temporal remote sensing data (SPOT, aerial pictures). The GIS supports the simulation of the composite effect at the regional scale of highly variable and discontinuous component hydrologic processes operating at the catchment scale, in order to simulate inter‐annual aquifer recharge and response to climatic scenarios at the regional scale.
Catchment infiltration I: Distribution of variables
Authors: ROGOWSKI ANDREW S , HOOVER JAMES R
Published: March 2007

Environmental modelling usually requires spatially distributed inputs for model operation. We propose that such inputs are best obtained from field measured data. Geographic information systems (GIS) provide a logical framework to distribute measured inputs spatially, to manipulate ensuing data fields during analysis, and to display the results. This paper describes a study conducted on a 123 km2catchment in Pennsylvania. The purpose was to evaluate how spatial variability of macroporosity affects distribution of other infiltration‐related parameters. We measured sorptivity, conductivity and macroporosity at specific points within a catchment, and interpolated their spatial distributions by kriging. The measurements were made with ring and disk infiltrometers, sampling locations were geo‐referenced with a global positioning system (GPS), and data were analysed using geostatistical techniques in a GIS context. Field values (hard data) were supplemented bysoft dataderived from cumulative distribution functions (cdfs) and available soil maps. Results showed that, when spatial variability associated with macroporosity was removed, infiltration parameters became less variable. Observed correlation among measured parameters suggested a form of potential transfer functions. We conclude that infiltration can be modelled at either the farm or catchment scale if macroporosity and spatial variability of infiltration parameters are adequately defined, and we suggest approaches which can be used in a GIS context to attain that goal.
Data models – progress towards their description using EXPRESS
Authors: BUCHANAN HUGH
Published: March 2007

Data models are used in conjunction with geographic information. However, the tools for describing such data models have been limited in their capabilities. Data description languages that have been developed elsewhere offer a set of tools for describing data models for geographic information. One of these languages is EXPRESS, which has recently been used for describing geographic information data models in a project concerned with creating a European standard for geographic information data exchange. This paper discusses three of the important issues that need to be addressed to utilize EXPRESS with geographic information. The first was whether to characterize real world phenomena as features classified by their geometric characteristics or alternatively whether to characterize them as named object types. The second was whether to insist that all data conformed to a common semantic data model, or whether to leave this flexible in order to minimize the restrictions on users, and thereby encourage use. Finally, a method was required to ensure that the EXPRESS description of a dataset is always associated with the data set itself, and therefore that the interpretation of the data set is made with all available information.
A visual programming language for spatial modelling in GIS
Authors: HADDOCK GREGORY , JANKOWSKI PIOTR
Published: March 2007

An integration between a visual programming environment and GIS has been developed to create and run spatial models. The visual programming environment provides graphical objects to create flowchart‐like models of spatial phenomena using GIS data. The integrated system is object‐oriented and designed to lessen the technical burdens of GIS programming. The system capabilities are demonstrated using a hydrological model example, and the model execution speed is compared with an equivalent model implementation in a traditional raster‐based modelling system.
Catchment infiltration II: Contributing areas
Authors: ROGOWSKI ANDREW S
Published: March 2007

This study considers two issues of interest to the hydrologic and geographical information systems community. One deals with identifying the spatial distribution of infiltration and runoff contributing areas. The other addresses process modelling within a GIS framework. The study operates on the premise that partitioning of precipitation into runoff or infiltration depends on rainfall intensity and on soil properties. The problem is that neither local rainfall intensity, nor soil properties such as infiltration capacity and macroporosity are known well enough for all points of a catchment and need to be estimated. We infer local intensity from the interpolated distribution of cumulated rain depths over the catchment and record duration at the official met site. Measured values of sorptivity and hydraulic conductivity define infiltration. Negative head infiltration describes macroporosity. To scale‐up measured point values to larger areas and to model infiltration and macropore continuity at a catchment scale we use geostatistical kriging and conditional simulation together with standard GIS techniques of overlay manipulation. Results delineate areas contributing to runoff and infiltration and relate them to macroporosity. By intersecting overlays of precipitation with those of infiltration we create alternate GIS masks targeting specific portions of the watershed as either runoff or infiltration contributing zones. Choice of cell size and time interval define the scales of averaging for the application. Kriged surfaces illustrate the distribution of catchment infiltration, while conditional simulation provides a mechanism to define model uncertainty.
Selecting conservation reserves using species‐covering models: Adapting the ARC/INFO GIS
Authors: GERRARD ROSS A , CHURCH RICHARD L , STOMS DAVID M , DAVIS FRANK W
Published: March 2007

Conflicts between human development of the landscape and conservation of biodiversiry will continue to grow. Given this reality, there have been a number of attempts to model the optimal selection of conservation reserve sites such that maximum biodiversity protection can be attained within a limited budget for land acquisition. Here we adapt the Location‐Allocation module of ARC/INFO to solve the problem of representing, or covering, as many species as possible in a fixed number of selected reserve sites. Resident ARC/INFO solution routines are applied to an innovative ‘logical’ network that converts the problem of optimal reserve selection into a problem of optimal facility placement, which the Location‐Allocation module can recognize and solve. Use of this unique logical network structure as input to ARC/INFO's internal solvers makes possible, compared to previous methods, a much tighter integration of spatial optimization tools with mapping and database tools, all of which are internal to the GIS and accessed via a menu‐driven interface. The main advantage is that users of public domain data (such as the US Gap Analysis data) can conduct their own explorations of possible reserve systems without having to acquire and master optimization packages and reformat model output data for GIS display and post‐analysis of solutions. Our sample application uses species data from south‐western California. We also present a second major form of species‐covering model grounded in the same logical network. This enhanced modcl accommodates weighting of species by their conservation importance, thus allowing reserve systems to be designed around the protection of the most threatened or vulnerable biota.
The Geographer's Craft: Teaching GIS in the Web
Authors: FOOTE KENNETH E
Published: March 2007

The Geographer's Craft is a two‐semester course introducing GIS and geographic research methods using active‐learning, problem‐solving techniques. All of the materials for the course were developed in hypertext form in the World‐Wide Web (WWW). The organization of this electronic textbook and laboratory manual is explained and related to principles for using the WWW to enrich GIS education. Teaching strategies are discussed as are lessons learnt in developing hypertext courseware. The value of enlisting student participation in the development process is stressed. Note is made of the ways in which Web‐based materials may lead to the emergence of distance of education programmes in GIS. The project homepage ishttp://www.utexas.edu/depts/grg/gcraft/contents.html
The NCGIA core curricula in GIS and remote sensing
Authors: KEMP KAREN K
Published: March 2007

Since the development of the original NCGIA Core Curriculum in GIS (Goodchild and Kemp 1990), the National Center for Geographic Information and Analysis has been providing support and direction to the GIS education community. Following the success of the original Core Curriculum, three new curricula are now under development. All are being constructed and distributed on the World‐Wide Web and involve international authorship and editorial input. This paper outlines the origins of these projects and some of the issues related to the development of Web‐based instructional materials that they raise.
Capacity Constraints and Hedge Fund Strategy Returns
Authors: Naik Narayan Y. , Ramadorai Tarun , Stromqvist Maria
Published: March 2007

Hedge funds have generated significant absolute returns (alpha) in the decade between 1995 and 2004. However, the level of alpha has declined substantially over this period. We investigate whether capacity constraints at the level of hedge fund strategies have been responsible for this decline. For four out of eight hedge fund strategies, capital inflows have statistically preceded negative movements in alpha, consistent with this hypothesis. We also find evidence that hedge fund fees have increased over the same period. Our results provide support for the

Berk and Green (2004)

rational model of active portfolio management.
The Performance of Hedge Fund Strategies and the Asymmetry of Return Distributions
Authors: Ding Bill , Shawky Hany A.
Published: March 2007

We present hedge fund performance estimates that adjust for stale prices, Fama‐French risk factors and skewness. We contrast these new performance estimates with traditional performance measures. Using three‐factor models to adjust for staleness in prices and to incorporate Fama‐French factors along with the Harvey‐Siddique (2000) two‐factor model that incorporates skewness, we find that for the period 1990–2003, all hedge fund categories achieve above average performance when measured against an aggregate market index. More significantly, however, when we estimate performance at the individual hedge fund level, we discover that only 40 to 47% of the funds are shown to achieve an above average performance over that time period depending on the model used. These results have important implications for investors, endowments and pensions when they choose hedge fund managers.
The Evolution of an Innovation System in a Rural Area: The Case of La Pocatière, Québec
Authors: DOLOREUX DAVID , DIONNE STÈVE , JEAN BRUNO
Published: March 2007

This article aims to examine the development trajectory of a local innovation system in a rural region, namely La Pocatière, Québec (Canada), from an extended historical perspective (1830–2005). More specifically, its objective is to identify and analyse historical factors that give us a better understanding of the main determinants of the special heritage of this innovation system and of the institutional context in which it emerged and evolved. In short, the relation between the dynamics of innovation and institutional change is examined over time. Historical documents are analysed and the research provides a description and contextualization of the development of this innovation system, and of its spread, particularly in the farming and agricultural‐science sector initially, and subsequently in technological and industrial areas (physical technologies and the transport equipment industry). Four main periods are described, corresponding to changes in types of institutional behaviour in relation to innovation: a phase of setting up pioneering institutions and innovations (1827–1911), a phase of growth and influence of the agricultural‐science institutions (1911–62), a phase of rupture, economic diversification and development of the technological cluster (1962–97), and a phase of redeployment and growing complexity of the elements of the innovation system (1997–2005).
City‐Regions, Neoliberal Globalization and Democracy: A Research Agenda
Authors: PURCELL MARK
Published: March 2007

This paper argues that research on city‐regions could benefit from more sustained and critical attention to the question of democracy. That is, it should examine more closely how decisions in city‐regions are made, why they are made that way, and how they can be made more democratically. Much current research on politics in cities has framed the issue in terms of citizenship. That work has produced great insight. However, the attention to citizenship has prompted very little attention to democracy, even though the two concepts are deeply intertwined. Current interest in city‐regions opens up the possibility that a vibrant line of research on democracy can be added to and engage with that on citizenship.
Connecting the gendered door: women, violence and doorwork*
Authors: Hobbs Dick , O'Brien Kate , Westmarland Louise
Published: March 2007

This paper explores the emerging role of women who work as ‘bouncers’, or doorstaff, in the night‐time economy and examines how the cultural capital of the female bouncer is connected to the methods utilized to control licensed premises. It is drawn from a study that combined ethnographic observations and interviews in five major UK cities which explored a diverse range of issues such as gendered bodies, femininities and violence; the changing needs of the night‐time economy in the UK and the experiences of women engaged in ‘non‐traditional’ occupations. In this paper, we draw on interview data with one particular category of female door staff; women who share similar histories of exposure to violence and violent cultures, and we examine how their experiential knowledge of violence equips them with the resources to ‘work the doors’. Our attention focuses on this group of women, who we refer to as ‘The Connected’, and examine how they are ‘doing gender’ when they negotiate violence ‘on the door’
The changing practice of eating: evidence from UK time diaries, 1975 and 20001
Authors: Cheng Shu‐Li , Olsen Wendy , Southerton Dale , Warde Alan
Published: March 2007

This paper examines some central themes about change in consumption behaviour through an empirical investigation of the practice of eating. It analyses patterns of food consumption in the UK using time diary data from 1975 and 2000. The practice of eating is decomposed into four component activities which are used to explore systematically the inter‐relationships between social processes – such as commodification and temporal fragmentation – and ways of providing and consuming food. It charts the expansion of eating out, the degree to which it substitutes for other eating activities, and the implications of its development for social relations and the temporal organization of daily life. Analysis reveals that food consumption continues to be differentiated along established lines of social division, although the content of those divisions has changed and varies across components of the practice. Increasing commodification of the food chain is documented, but without appearing to have a corrosive impact on household organization or social relationships. While tendencies indicative of temporal fragmentation are revealed, counter‐tendencies exist which suggest that the practice of eating is resilient to many forms of external pressure. Finally, the application of a practice‐based analytical approach permits critical evaluation of theories of social transformation.