bluuebunny/crossref_metadata_2025 huggingface dataset:
Hindsight modulates Delta expression duringDrosophilacone cell induction
Authors: Pickup Amanda T. , Ming Liang , Lipshitz Howard D.
Published: February 2009

The induction of cone cells in the Drosophila larval eye disc by the determined R1/R6 photoreceptor precursor cells requires integration of the Delta-Notch and EGF receptor signaling pathways with the activity of the Lozenge transcription factor. Here, we demonstrate that the zinc-finger transcription factor Hindsight (HNT) is required for normal cone-cell induction. R-cells in which hindsight levels are knocked down using RNAi show normal subtype specification, but these cells have lower levels of the Notch ligand Delta. We show that HNT functions in the determined R1/R6 precursor cells to allow Delta transcription to reach high enough levels at the right time to induce the cone-cell determinants Prospero and D-Pax2 in neighboring cells. The Delta signal emanating from the R1/R6 precursor cells is also required to specify the R7 precursor cell by repressing seven-up. As hindsight mutants have normal R7 cell-fate determination, we infer that there is a lower threshold of Delta required for R7 specification than for cone-cell induction.
Jasmonic acid control of GLABRA3 links inducible defense and trichome patterning inArabidopsis
Authors: Yoshida Yuki , Sano Ryosuke , Wada Takuji , Takabayashi Junji , Okada Kiyotaka
Published: February 2009

Once attacked by herbivores, plants regenerate new leaves with increased trichome density as an inducible defense. Trichomes are specified from neighboring epidermal cells through local cell-cell interactions in the leaf primordia. However, the molecular mechanism of how herbivore-induced damage at older leaves remodels the pattern of trichome fate specification at newly forming leaves is largely unknown. In this study, we show that mutations in either the biosynthetic or signaling pathway of jasmonates (JAs),long-distance wound signals, abolish the wound-induced formation of trichomes. To identify the factors linking JA signaling to trichome fate specification,we isolated a novel class of mutants, unarmed (urm), which lack trichome induction but show otherwise normal responses to JAs. URM9 encodes an Importin β family protein, and URM23 is identical to TRANSPARENT TESTA GLABRA1 (TTG1), the product of which interacts with the bHLH transcription factor GLABRA3 (GL3). Loss of either URM9 or URM23 disrupts the subnuclear localization of GL3, thus implicating GL3 in trichome induction. The expression of GL3 was enhanced by JA treatment prior to trichome initiation. Genetic analysis of multiple trichome mutants shows that GL3, in concert with the R2R3-Myb transcription factor GLABRA1 (GL1), promotes trichome fate in response to JA in a dosage-dependent manner. These results indicate that GL3 is a key transcription factor of wound-induced trichome formation acting downstream of JA signaling in Arabidopsis.
An essential role for the RNA-binding protein Smaug during theDrosophilamaternal-to-zygotic transition
Authors: Benoit Beatrice , He Chun Hua , Zhang Fan , Votruba Sarah M. , Tadros Wael , Westwood J. Timothy , Smibert Craig A. , Lipshitz Howard D. , Theurkauf William E.
Published: February 2009

Genetic control of embryogenesis switches from the maternal to the zygotic genome during the maternal-to-zygotic transition (MZT), when maternal mRNAs are destroyed, high-level zygotic transcription is initiated, the replication checkpoint is activated and the cell cycle slows. The midblastula transition(MBT) is the first morphological event that requires zygotic gene expression. The Drosophila MBT is marked by blastoderm cellularization and follows 13 cleavage-stage divisions. The RNA-binding protein Smaug is required for cleavage-independent maternal transcript destruction during the Drosophila MZT. Here, we show that smaug mutants also disrupt syncytial blastoderm stage cell-cycle delays, DNA replication checkpoint activation, cellularization, and high-level zygotic expression of protein coding and micro RNA genes. We also show that Smaug protein levels increase through the cleavage divisions and peak when the checkpoint is activated and zygotic transcription initiates, and that transgenic expression of Smaug in an anterior-to-posterior gradient produces a concomitant gradient in the timing of maternal transcript destruction, cleavage cell cycle delays,zygotic gene transcription, cellularization and gastrulation. Smaug accumulation thus coordinates progression through the MZT.
Zebrafish diencephalic A11-related dopaminergic neurons share a conserved transcriptional network with neuroendocrine cell lineages
Authors: Löhr Heiko , Ryu Soojin , Driever Wolfgang
Published: February 2009

Vertebrate dopaminergic neurons develop in distinct neural territories to constitute one of the major neuromodulatory systems. We have identified a zebrafish mutation in the bHLH-PAS family member arnt2, based on a strong reduction in cell number of specific dopaminergic neuron groups in the hypothalamus and posterior tuberculum. Knockdown of sim1 causes a dopaminergic phenotype similar to arnt2 mutants, suggesting that Sim1 acts as a binding partner of Arnt2, similar to their role in hypothalamic neuroendocrine cell specification. sim1, arnt2 and otp are co-expressed in dopaminergic neurons, and combined overexpression of Sim1 and Otp leads to formation of supernumerary dopaminergic neurons in the ventral diencephalon. Arnt2, Sim1 and Otp thus are core components of a conserved transcriptional network, which specifies neuroendocrine as well as A11-related dopaminergic neurons in the fish hypothalamus and posterior tuberculum. Our data suggest a common evolutionary origin of specific hypothalamic neuroendocrine and dopaminergic systems.
Multiple Sourcing and Procurement Process Selection with Bidding Events
Authors: Tunca Tunay I. , Wu Qiong
Published: February 2009

We examine the procurement process selection problem of a large industrial buyer who employs reverse auctions for awarding procurement contracts. We contrast two classes of commonly used strategies under multiple sourcing; namely, single-stage reverse auctions, and two-stage processes where price-quantity adjustments between the buyer and the suppliers follow a first-stage reverse auction. Deriving bounds of efficiency for these two classes of procurement processes under convex supplier production costs, we present insights on the conditions under which each class is preferable for the buyer. Considering the effect of contracting and processing costs, a single-stage process is likely to be preferable to a two-stage process when the number of bidding suppliers is high, especially when capacity is rigid. A two-stage process with one information transfer in the second stage may be the preferred procurement mode when production is highly scalable, i.e., when the marginal production cost increase with increased production is small. When the number of suppliers is low, the effect of a decrease in production scalability depends on the current scalability level. For high scalability levels, a decrease in production scalability may decrease the efficiency of both single-stage and simple two-stage processes, whereas for low scalability levels, it tends to increase efficiency for both of these process classes. A decrease in production costs makes employing simple processes more attractive when production is highly scalable or when supplier capacity is rigid. For intermediate production scalability, however, a cost decrease may make employing two-stage processes with multiple information transfers in the second round preferable for the buyer.
Information Market-Based Decision Fusion
Authors: Perols Johan , Chari Kaushal , Agrawal Manish
Published: February 2009

Improved classification performance has practical real-world benefits ranging from improved effectiveness in detecting diseases to increased efficiency in identifying firms that are committing financial fraud. Multiclassifier combination (MCC) aims to improve classification performance by combining the decisions of multiple individual classifiers. In this paper, we present information market-based fusion (IMF), a novel multiclassifier combiner method for decision fusion that is based on information markets. In IMF, the individual classifiers are implemented as participants in an information market where they place bets on different object classes. The reciprocals of the market odds that minimize the difference between the total betting amount and the potential payouts for different classes represent the MCC probability estimates of each class being the true object class. By using a market-based approach, IMF can adjust to changes in base-classifier performance without requiring offline training data or a static ensemble composition. Experimental results show that when the true classes of objects are only revealed for objects classified as positive, for low positive ratios, IMF outperforms three benchmarks combiner methods, majority, average, and weighted average; for high positive ratios, IMF outperforms majority and performs on par with average and weighted average. When the true classes of all objects are revealed, IMF outperforms weighted average and majority and marginally outperforms average.
Private Network EDI vs. Internet Electronic Markets: A Direct Comparison of Fulfillment Performance
Authors: Yao Yuliang , Dresner Martin , Palmer Jonathan
Published: February 2009

Prior literature has documented the performance benefits from the use of electronic data interchange (EDI) and the Internet. Using purchase and fulfillment records from the U.S. government's Federal Supply Service, we provide a direct comparison of performance between a private network EDI channel and an Internet electronic market. Performance is measured using order cycle time and complete orders fulfilled. Our findings show that the Internet-based electronic market outperforms the EDI-based channel on these two important measures. Order cycle times were significantly lower when using the Internet-based electronic market, whereas the percentage of complete shipments was significantly higher after controlling for product, transaction, seller, and buyer-specific factors. The electronic market even outperforms the EDI channel when buyer and transaction characteristics favor the use of EDI. Because EDI is still prevalent in many industries, these results point to the gains that may be realized by switching to the newer technology.
Iterating between lessons on concepts and procedures can improve mathematics knowledge
Authors: Rittle‐Johnson Bethany , Koedinger Kenneth
Published: February 2009

Background Knowledge of concepts and procedures seems to develop in an iterative fashion, with increases in one type of knowledge leading to increases in the other type of knowledge. This suggests that iterating between lessons on concepts and procedures may improve learning.

Aims The purpose of the current study was to evaluate the instructional benefits of an iterative lesson sequence compared to a concepts‐before‐procedures sequence for students learning decimal place‐value concepts and arithmetic procedures.

Samples In two classroom experiments, sixth‐grade students from two schools participated (N = 77 and 26).

Method Students completed six decimal lessons on an intelligent‐tutoring systems. In the iterative condition, lessons cycled between concept and procedure lessons. In the concepts‐first condition, all concept lessons were presented before introducing the procedure lessons.

Results In both experiments, students in the iterative condition gained more knowledge of arithmetic procedures, including ability to transfer the procedures to problems with novel features. Knowledge of concepts was fairly comparable across conditions. Finally, pre‐test knowledge of one type predicted gains in knowledge of the other type across experiments.

Conclusions An iterative sequencing of lessons seems to facilitate learning and transfer, particularly of mathematical procedures. The findings support an iterative perspective for the development of knowledge of concepts and procedures.
Contact and other‐race effects in configural and component processing of faces
Authors: Rhodes Gillian , Ewing Louise , Hayward William G. , Maurer Daphne , Mondloch Catherine J. , Tanaka James W.
Published: February 2009

Other‐race faces are generally recognized more poorly than own‐race faces. There has been a long‐standing interest in the extent to which differences in contact contribute to this other‐race effect (ORE). Here, we examined the effect of contact on two distinct aspects of face memory, memory for configuration and for components, both of which are better for own‐race than other‐race faces. Configural and component memory were measured using recognition memory tests with intact study faces and blurred (isolates memory for configuration) and scrambled (isolates memory for components) test faces, respectively. Our participants were a large group of ethnically Chinese individuals who had resided in Australia for varying lengths of time, from a few weeks to 26 years. We found that time in a Western country significantly (negatively) predicted the size of the ORE for configural, but not component, memory. There was also a trend for earlier age of arrival to predict smaller OREs in configural, but not component, memory. These results suggest that memory for configural information in other‐race faces improves with experience with such faces. However, as found for recognition memory generally, the contact effects were small, indicating that other factors must play a substantial role in cross‐race differences in face memory.
Reference intervals in evaluation of maternal thyroid function during the first trimester of pregnancy
Authors: Springer Drahomira , Zima Tomas , Limanova Zdena
Published: February 2009

Background

Insufficient function of the thyroid gland can cause low concentrations of thyroid gland hormones which are necessary for the proper development of the foetus brain, especially during the beginning of pregnancy. We determined the reference interval for TSH in the first trimester of pregnancy and the decision point for anti-TPO antibodies' positivity.

Methods

We tested 5520 women from the central part of the Czech Republic during the first trimester of pregnancy for serum TSH, anti-TPO and FT4 by chemiluminometric immunoanalysis on an ADVIA Centaur system (Siemens). The reference interval for TSH during the first trimester of pregnancy was determined using the log transformation, and then summarized as the geometrical mean (95% CI); following which, a suitable decision point for anti-TPO positivity was set.

Results

The reference interval for TSH was determined to be 0.06–3.67 mU/l. The suppression of TSH was found in 2.93% of the women; a raised concentration of TSH had been found in 4.48% of the women. For anti-TPO, the cut-off was established at 143 kU/l; 11.2% of the pregnant women were found to be anti-TPO positive.

Conclusion

Determination of the reference interval for TSH during early pregnancy is one of the basic requirements when implementing a general examination of the thyroid gland at the beginning of pregnancy. The decision level for positivity of anti-TPO is more than double the manufacturer's reference interval.
Neutron Transmutation Doping and Radiation Hardness for Solution-Grown Bulk and Nano-Structured ZnO
Authors: Flitsiyan Elena S. , Swartz Casey M. , Peale Robert E. , Lupan Oleg , Chernyak Leonid , Chow Lee , Vernetson William G. , Dashevsky Zinovi
Published: February 2009

It is shown that solution-grown ZnO nanostructures exhibit enhanced radiation hardness against neutron irradiation as compared to bulk material. The decrease of the cathodoluminescence intensity after irradiation at a neutron dose of 6 × 1016 cm−2 in ZnO nanostructure is nearly identical to that induced by a dose of 1.5 × 1014 cm−2 in bulk material. The damage introduced by irradiation is shown to change the nature of electronic transitions responsible for luminescence. The change of excitonic luminescence to the luminescence related to the tailing of the density of states caused by potential fluctuations occurs at an irradiation dose around 6×1016 cm−2 and 5×1014 cm−2 in nanostructured and bulk materials, respectively.

Hall measurements before and after annealing determined the effect of dose on resistance, mobility, and carrier concentration. Annealing decreased the sheet resistance, increased the mobility, and increased carrier concentration for all doses. While the concentration of carriers in the control sample increased 200-fold after annealing, the increase was ∼1000-fold for the irradiated samples. Annealed irradiated samples showed a maximum carrier concentration increase of about 60x over the unirradiated sample. Interestingly, neutron irradiation increased the mobility even in the un-annealed samples.
The Effects of Partial Crystallinity on the Hydrogen Permeation Properties in Amorphous Metallic Systems
Authors: Brinkman Kyle S. , Fox Elise B , Korinko Paul , Adams Thad , Jurgensen Arthur
Published: February 2009

It is recognized that hydrogen separation membranes are a key component of the emerging hydrogen economy. A potentially exciting material for membrane separations are bulk metallic glass materials due to their low cost, high elastic toughness and resistance to hydrogen ‘embrittlement’ as compared to crystalline Pd-based membrane systems. However, at elevated temperatures and extended operation times structural changes including partial crystallinity may appear in these amorphous metallic systems. A systematic evaluation of the impact of partial crystallinity/devitrification on the diffusion and solubility behavior in multi-component Metallic Glass materials would provide great insight into the potential of these materials for hydrogen applications. This study will report on the development of time and temperature crystallization mapping and their use for interpretation of ‘in-situ’ hydrogen permeation at elevated temperatures.
Effect of Cr Addition on the Multiphase Equilibria in the Nb-rich Nb-Si-Ti System - Thermodynamic Modeling and Designed Experiments
Authors: Yang Ying , Bewlay Bernard P , chen Shuanglin , Jackson M R , Chang Y. A.
Published: February 2009

Refractory Metal Intermetallic Composites (RMICs) based on the Nb-Si system are considered as candidates of next-generation high temperature materials (i.e. >1200°C). Ti and Cr have been shown to have beneficial effects on the oxidation resistance and mechanical properties of Nb-Si alloys. Phase equilibria in the Nb-Si-Ti system have been studied in detail. The present study has investigated multiphase equilibria in the Nb-Si-Ti alloys with Cr additions via an approach of integrating thermodynamic modeling with designed experiments. The alloying effects of Cr on the microstructure of the Nb-Si-Ti alloys are described using both phase equilibria and solidification paths that were calculated from the thermodynamic description of the Nb-Cr-Si-Ti system developed in the present study.
Dynamics of Atomic Ordering in Bulk and Thin Film Intermetallic Alloys: A Complementary Approach to Atomic Migration
Authors: Pfeiler Wolfgang , Püschl Wolfgang , Issro Chaisak , Kozubski Rafal , Pierron-Bohnes Veronique
Published: February 2009

One of the foremost challenges in today's materials science is the design and development of materials with physical properties customized for technical application. Due to their excellent corrosion resistance and their advantageous mechanical and in many cases also magnetic properties, intermetallic alloys are among the most important materials of the 21st century. Most of their outstanding qualities are linked to long-range order, the fact that unlike atoms are preferred as neighbours, which then segregate to different sublattices. In most intermetallics atomic order persists up to rather high temperatures, if not up to melting. However, connected with the entropy gain, the degree of order depends on temperature and thereby the stability of the designed beneficial materials properties is affected. By monitoring changes in the degree of atomic order an access to atom migration is gained, which is complementary to the usual diffusion experiments, where the degree of order is not changed on average. It is shown in this review on some selected examples how an adequate thermal treatment of the samples in combination with the experimental approach gives detailed information on atom jump mechanisms and structural changes, especially if experiment is combined with up-to-date kinetic Monte Carlo simulations.
First-principles Investigations of Point Defect Behavior and Elastic Properties of TiNi Based Alloys
Authors: Lu Jian-min , Hu Qing-miao , Yang Rui
Published: February 2009

First-principles calculations by the use of a plane-wave pseudopotential method are performed to investigate intrinsic point defect behavior in TiNi. The results show that TiNi is an antisite type intermetallic compound. The calculated interaction energies between the point defects demonstrate that Ti antisites are attractive to each other whereas Ni antisites are mutually repulsive. The attraction between Ti antisites indicates that excess Ti in TiNi may agglomerate so that a Ti-rich phase can easily precipitate. The repulsion between Ni antisites implies that the excess Ni is of certain solubility in TiNi. This result explains well the asymmetric feature of TiNi field on the binary phase diagram. In order to understand the correlation between the composition dependent elastic modulus and martensitic transformation (MT) temperature, the elastic moduli critical to MT, i.e., c′ and c44, are calculated as a function of the composition of the off-stoichiometric TiNi and a series of ternary TiNi-X alloys, by the use of exact muffin-tin orbital method in combination with coherent potential approximation. It turns out that, generally speaking, the early transition metal (TM) alloying elements in the periodic table increase c′ but decrease c44; the middle ones increase both c′ and c44, whereas the late ones decrease c′ but increase c44. An examination of the theoretical composition dependent elastic modulus and the experimental MT temperature shows that the MT temperature is more sensitive to the variation of c44 than to that of c′.
The persistence of workplace ideology and identity across communicative contexts
Authors: Cotter Colleen , Marschall Daniel
Published: February 2009

We examine the discursive construction of organizational ideology, its role in sustaining membership in a workplace community, and the achievement of community cohesion in a workplace environment through the practice and reinforcement of communicative norms and identities that reflect this ideology. Using a range of spoken and written discourse examples from internal employee listservs, company documents, ethnographic interviews, and participant observation over a continuous four-year period during a time of rapid change at a small U.S. software development firm, we articulate interactional processes by which community membership and organizational alignments are conceptualized, established, challenged, and sustained in the day-to-day physical workplace and the concurrent online sphere. The longitudinal dimension demonstrates how the adoption and interpretation of the firm’s organizational ideology, which contributes to the formation and maintenance of its identity as an occupational community, persists across time and channels of transmission.
Research on transnational Yucatec Maya-speakers negotiating multilingual California
Authors: Whiteside Anne
Published: February 2009

This project combined methodologies from linguistic anthropology, participatory action research and interactional sociolinguistics. Data was collected from participant observation, four case studies, extensive interviews and a language and literacy survey. Multilingual conversations were recorded and analyzed with Conversation Analysis, with a focus on actions and identities as they emerge through enacted stance. The analysis was informed by concepts taken from the anthropology and sociology of transnationalism. The study shows four Maya-speaking individuals negotiating highly multilingual social worlds, where English, when it appears, is more often lingua franca than dominant code, and where participants use their various languages strategically and contingently to accomplish their various goals. These choices are constrained by their status as workers at the bottom rung of a social field characterized by undocumented status and the persistence of colonial discourses. Recommendations for research and practice based on research findings: -reconsideration of second language pedagogies for such immigrant populations -the use of stance in the analysis of multilingual conversations -more research on undocumented status and how it contributes to the silencing of minority language populations -the use of participatory research methods in studies of undocumented and indigenous communities
Student control in the second language classroom
Authors: Kissau Scott , Quach Lan Hue
Published: February 2009

Male disinterest in second language (L2) programs has in recent years been well documented. In attempt to explain the lack of male participation recent studies have suggested that traditional teacher-centered second and foreign language classrooms deprive males of the internal control they crave. Using data from a large-scale study by Author (2006), in this article the researcher attempts to determine if gender differences exist in perceptions of control in the L2 classroom and further, if perceptions of control appear to be an important factor in whether or not students pursue L2 studies. Approximately 500 students studying French as a second language in Grade 9 completed a questionnaire. The data were then explored in interviews with students and teachers. Results suggest that control is an important factor in the decision to study French and that boys perceive themselves to have less control in the L2 classroom than do girls. Suggestions for how such gender differences can be addressed are also discussed.
“But big is a funny word”
Authors: Alanen Riikka , Jäppinen Aini-Kristiina , Nikula Tarja
Published: February 2009

In recent years, foreign-language mediated instruction (immersion, content-based language learning and teaching) has been studied from various perspectives. In the following study, a single event from a Finnish third-grade EFL-mediated geography lesson is studied by combining insights from three research approaches: sociocultural, socio-cognitive, and discourse-pragmatic. The data analysis focuses on how during concept formation, the participants use commonplace means present in every classroom – textbook and chalkboard, spoken and written, verbal and nonverbal communicative means – to construct knowledge and its social context. The results indicate that there exist strong parallels among the ways the various means are used by the participants in the activity, and that this pattern coincides with the changes in the teacher’s control of classroom interaction. Methodologically, the multiple perspective adopted in the study highlights the nature of social interaction and the complex issues involved in the teaching and learning processes in the classroom context.
Can green infrastructure promote urban sustainability?
Authors: Mell I. C.
Published: February 2009

In 2000, a UK government white paper promoted the prospect of an urban renaissance in the UK to be developed through a series of urban renewal initiatives to create better places for living, working and recreation. Eight years on, there continues to be a policy drive promoting better quality environments through integrative design, social inclusion and public participation. However, whether urban renewal can succeed without a progressive integration of multi-functional green spaces into the urban matrix is still uncertain. This paper proposes that green infrastructure can play a pivotal role in urban renaissance by providing a complementary green matrix of spaces that offer multi-level benefits for human populations. Green infrastructure can also be viewed as simultaneously providing natural resource sinks to assist urban climate control, water management and provide important green networks in an increasingly urbanised Britain. Due to the potential of green infrastructure to be ‘retrofitted’ into most environments, this paper argues that green infrastructures can be delivered across diverse urban environments in the UK to promote sustainable communities and landscape management. Overall, this paper will address how green infrastructure can be planned within urban environments to promote increased human integration, ecological sustainability and economic regeneration. Finally, it is suggested that the broader implications for climate control and economic regeneration delivered by green infrastructure integration will, in the long term, provide a base for a continued urban renaissance.
Intelligent transport systems in China
Authors: Wu J. , Sui Y. , Wang T.
Published: February 2009

The rapid development of the Chinese economy over the past 30 years has increased demand for passenger and freight transport considerably. Although restrictions on economic development have been alleviated by a major programme of road construction, China has begun to seek more sustainable ways of supporting transport development. Intelligent transport systems (ITS) have been introduced and a series of research has been conducted to take advantage of ITS applications in traffic management and control with significant social, economic and environmental benefits. This paper reviews the current use of ITS in China and presents policies, technologies, typical applications and recent activities in ITS development. The main achievements that reflect the current level of China's ITS development are described, in particular the ITS showcase programme and preparation for the 2008 Olympic Games. Finally, the paper discusses China's future ITS plans.
Towards probabilistic projections of climate change
Authors: Hewitt C. D. , Goodess C. M. , Betts R. A.
Published: February 2009

As evidence of climate change increases, so too are the effects of weather events and climate variability on civil engineering projects becoming increasingly recognised and understood. The changes indicated by the UKCIP02 scenarios, for example, suggest a number of threats and opportunities for the built environment. The Ensembles project will develop an ensemble climate prediction system for use across a range of timescales (from seasonal to decadal and longer) and spatial scales (from global to regional and local). The outputs from this European Commission funded project will allow further development, within a probabilistic framework, of tailored scenarios for urban areas developed as part of the UKCIP/EPSRC Building Knowledge for a Changing Climate programme. Examples of these projections for London Heathrow are presented; they illustrate the uncertainties in projected changes in extremes for urban and other sites. Modelling work that indicates the importance of representing urban areas within climate simulations is also presented.
Core competencies in the public sector
Authors: Worthington N. D.
Published: February 2009

The objective of this paper is to demonstrate the application of a strategic model for identifying core competencies within public sector organisation (e.g. local authorities and public corporations). Core competencies are defined as those activities that provide strategic advantage to an organisation. A strategic model has been developed, which is simple to use and can be adjusted to suit any public sector organisation. The model consists of criterion elements, which are used to assess the significance of a given activity; these elements are weighted to reflect the organisation's aims, values and strategic vision. The application of the model results in each activity having a percentage value, which can then be used to determine its core status and consequently, its potential for outsourcing, or supporting an in-house capability. The model is a simple, yet effective means of initial core competence decision-making. It is concluded that by applying the model, core competencies can be identified in a systematic manner, strategically linking them to an organisation's corporate aims and objectives.
Comparison of methods of assessing cycle routes
Authors: Parkin J. , Coward A.
Published: February 2009

This paper compares the Institution of Highways and Transportation (IHT) Guidelines for Cycle Audit and Cycle Review with two methods of assessment based on research into perceptions of risk by cycle users in a study of fifteen routes from ten origins into Chester, the county town of Cheshire. One method uses risk ratings for components of a journey and the other uses variables based on generic features of the journey. The most direct route and a reasonable alternative were analysed for five origins. A large range of review scores from the IHT, risk rating and generic feature methods was estimated, demonstrating widely varying circumstances for cycle traffic including routes that were both heavily motor trafficked or were traffic free. Very strong correlation was found between the risk rating method and the IHT method (−0·877); moderate correlation was found between the generic feature method and the IHT method (−0·564). Based on the ease of use of the risk rating and generic feature methods, it is recommended that these are used more extensively for cycle route assessment. It is also recommended that the IHT guidelines are developed further to allow for a full and proper estimate of the impact of large junctions on routes. Further, it is recommended that more work be undertaken on the perceptions of risk of cycle users in order to determine coefficients for a wider range of carriageway and junction types.
Optimizing Pedotransfer Functions for Estimating Soil Bulk Density Using Boosted Regression Trees
Authors: Martin M. P. , Lo Seen D. , Boulonne L. , Jolivet C. , Nair K. M. , Bourgeon G. , Arrouays D.
Published: February 2009

Pedotransfer functions (PTFs) are used to estimate certain soil properties that are difficult and costly to measure from others more easily available. Bulk density is one important soil property. Although not requiring complex analysis, its measurement remains time consuming and is lacking in many soil surveys. For several decades, PTFs have been developed for predicting soil bulk density. Most of these PTFs are suited only for specific agro‐pedo‐climatic conditions, however, and can be applied only within a limited geographic area. In this study, we derived and experimented with two new PTFs based on a multiple additive regression trees (MART) method, and assessed their performance compared with existing PTFs when applied to a country‐level soil database, the Réseau de Mesures de la Qualité des Sols (RMQS) survey network. This database was designed to include the major soil types and land uses in France. The first proposed PTF (Model m) involves only three predictors typically found in the existing PTFs for bulk density (C content and texture) and the second one (Model M) includes eight easily accessible quantitative and qualitative predictors (e.g., soil taxon). Both models significantly outperformed existing PTFs. Without arbitrarily partitioning the data set before fitting the model, the m and M MART models yielded R2 values of 0.83 and 0.94, respectively. The predictive quality on independent data, assessed using cross‐validation, was also improved compared with published PTFs, with R2 reaching 0.62 and 0.66 and root mean square prediction errors of 0.123 and 0.117 Mg m−3 for the two MART models.
Axisymetrical Infiltration in Soil Imaged by Noninvasive Electrical Resistivimetry
Authors: Batlle-Aguilar J. , Schneider S. , Pessel M. , Tucholka P. , Coquet Y. , Vachier P.
Published: February 2009

To progress in the monitoring and understanding of soil water processes, geophysical methods can be helpful because they are noninvasive and as such do not disturb either the structure or the water dynamics of the soil. In this study we attempt to image water infiltration dynamics under a tension infiltrometer in a vertical two‐dimensional (2D) plane using electrical resistivity tomography (ERT). Two‐dimensional images of soil electrical resistivity at different times were obtained using a Wenner array with 32 electrodes and a 10‐cm spacing during the infiltration of a Cl− or Br− solution at 0.36 and 0.34 M, respectively. This procedure allowed monitoring the development of the infiltration bulb through time. Both unipotential and multipotential infiltrations were performed and used to derive soil hydraulic conductivity and sorptivity values. Anion concentrations in soil samples taken after infiltration were compared with resistivity values obtained with ERT measurements. The axisymetrical pattern of the multipotential infiltration exhibited large distortions, well detected and imaged by the ERT and consistent with the anion concentration data. In general, images derived from 2D inversions of ERT measurements underestimated the depth of the infiltration bulb. Axisymetrical inversion software would be helpful for the interpretation of ERT data taken below tension disc infiltrometers. The ERT on a small scale seems a helpful and promising tool for deriving in situ soil hydraulic parameters and for monitoring infiltration processes without the need for placing sensors into the soil.
Using Hydrologic Patterns and Precipitation Data to Construct an Empirical Model for Understanding Cumulative Saturation
Authors: Morgan Charles P. , Stolt Mark H.
Published: February 2009

Soil morphology is often used as a predictor of water table levels in hydric soil determinations or other on‐site evaluations. These predictions are based on the assumption that the relationships between water table levels and morphologic properties were established during typical weather patterns. Because climatic factors such as precipitation and evapotranspiration vary widely from year to year, there are often concerns about the validity of using short‐term hydrologic data to predict longer term relationships. In this study, we monitored water table levels in three soils formed in glacial fluvial and till parent materials for 18 mo. Using these data, we developed a simple model that applies archived precipitation data and established hydrologic patterns to predict water table levels and cumulative saturation. The model was calibrated for each site through an iterative process. The minimal average differences between actual and predicted water table levels (<12 cm), R2 values (0.68–0.86), and the similarities between the cumulative saturation curves compiled from predicted and measured data suggested that the model performed well at predicting water table depths. Archived precipitation data (1950–1984) were applied to predict longer term cumulative saturation, cumulative saturation during a period of excessive wetness, and cumulative saturation associated with a period of moderate to extreme drought. The model showed that cumulative saturation can vary widely between years depending on climatic conditions. This variability in cumulative saturation should be considered when making land use decisions based on the identification of hydromorphic features such as redox depletions and concentrations.
Short‐Term Reducing Conditions Decrease Soil Aggregation
Authors: De-Campos Alfredo B. , Mamedov Amrakh I. , Huang Chi-hua
Published: February 2009

Upland soils in the midwestern United States are often ponded during the spring for days or weeks and may undergo reduction. Short‐term reducing conditions change the chemistry of the soil and that may affect soil aggregation. The objective of this study was to determine how changes in the redox status of the soil under a set of controlled temperature and light conditions can impact soil aggregation during short‐term flooding conditions. A biogeochemical reactor was built to achieve reducing conditions. Six different soils, three cultivated and three uncultivated, with different organic C contents were incubated (1:1.5 soil/water ratio) in the reactor for 1 h and 1, 3, 7, and 14 d. After each treatment, the soil solution was collected and analyzed for metals and dissolved organic C (DOC). A high‐energy moisture characteristic procedure was used to determine the aggregate stability of the incubated soil samples. A strong correlation was found between changes in the redox potential (Eh) and aggregate stability. As Eh decreased, aggregate stability decreased. The changes in redox‐sensitive elements (Mn and Fe), alkaline metals (Ca, Mg, and K), and DOC under reducing conditions were found to also contribute to decreased aggregate stability. The aggregate stabilities of cultivated soils were more sensitive to reducing conditions than those of uncultivated ones. The decrease in aggregate stability reached up to 21% in the cultivated soils and might be irreversible under field conditions. Short‐term reducing conditions may have detrimental effects on soil structure and water quality due to changes in soil aggregation and the chemistry of the soil solution.
Morphodynamics of Headcut Development and Soil Erosion in Upland Concentrated Flows
Authors: Wells Robert R. , Alonso Carlos V. , Bennett Sean J.
Published: February 2009

In agricultural regions, gully erosion is now recognized as a dominant source of soil loss, and the development and upstream migration of headcuts is critical to the initiation, incision, and dissection of these upland areas. This study examined the effect of soil texture on headcut development and migration using four common soils from the southeastern United States, tested on bed surface slopes ranging from 1 to 5% and overland flow rates ranging from 45 to 71 L min−1 In response to this flow, actively migrating headcuts developed with migration rates ranging from 0.00001 to 0.0025 m s−1, maximum scour depths ranging from 0.042 to 0.148 m, and sediment discharge rates ranging from 0.00017 to 0.0356 kg s−1 depending on the soil and boundary conditions imposed. Nearly all experimental runs resulted in steady‐state soil erosion, wherein the headcut developed attained a constant rate of migration, shape, and sediment discharge as a function of time. These experimental observations were successfully compared with predictive equations for mass conservation, jet entry angle, maximum scour depth, and migration rate developed for actively migrating headcuts in upland concentrated flows. These results further demonstrate that systematic headcut development can occur in a range of soils, slopes, and flow rates, and that modified jet impingement theory can be used to predict the erosional characteristics of these headcuts, thus providing the necessary analytical framework for improving soil erosion prediction technology.
Hydraulic Conductivity as Influenced by Stoniness in Degraded Drylands of Chile
Authors: Verbist K. , Baetens J. , Cornelis W.M. , Gabriels D. , Torres C. , Soto G.
Published: February 2009

Infiltration measurements in arid, stony soils are notoriously variable in visually homogeneous areas, and have been reported to be influenced by embedded stone fragments. This study aimed to identify the influence of rock fragment contents, orientation, and position within a small arid watershed on hydraulic conductivity in northern Chile. Two different measurement techniques were used, a single‐ring infiltrometer with constant ponding head and a tension infiltrometer, which were applied at both an undisturbed field site (44 locations along three transects) and on the disturbed <2‐mm soil fraction from the same locations. Variations in saturated and unsaturated hydraulic conductivities were observed when using different calculation methods, adding to the observed variability. For saturated conditions, only small differences in conductivities were observed between two calculation methods, whereas unsaturated hydraulic conductivities calculated by five different methods showed more important variations. Stone fragment content correlated significantly with both saturated and unsaturated conductivities, probably due to a positive correlation between stone content and coarse lacunar pore space. Slope orientations with higher amounts of stone fragments gave higher infiltration rates, as well as transects with steeper slopes and more, but smaller, rock fragments. When evaluating differences in infiltration rates observed along three transects in the watershed, variability could be mainly attributed to stone fragment content influences.
In Situ DRIFT Characterization of Organic Matter Composition on Soil Structural Surfaces
Authors: Ellerbrock Ruth H. , Gerke Horst H. , Böhm Christian
Published: February 2009

The properties of preferential flow path surfaces may affect transport processes in structured soil. Wetting and sorption depends on the organic matter (OM) at the effective outermost surface of flow paths, which is largely unknown locally with respect to OM composition and distribution. The objectives are to adapt Diffuse Reflectance infrared Fourier Transform (DRIFT) spectral analysis for the in situ characterization of coated crack surfaces and linings of earthworm burrow walls. The Kubelka‐Munk (KM) transformed DRIFT spectra are used to analyze OM composition in terms of the ratio between CH‐ (Band A) and C=O groups (Band B). The A/B ratio indicates a relation between hydrophobic and hydrophilic groups in OM. Disturbed soil samples are arranged (i) in standard cup (CUP) and (ii) larger box (BOX) devices; intact aggregate and burrow surfaces are prepared from clods with cracks and earthworm burrows. The disturbed samples with relatively homogeneous surfaces are used to compare data obtained from CUP with those from the BOX device. The A/B ratios are determined in a stepwise mapping‐type procedure and compared with pictures of the surfaces for inferring a spatial distribution of OM composition along transects. The DRIFT mapping results indicate negligibly small texture effects for the finer‐textural subsoil samples for which the applicability of KM is not restricted. For intact surfaces like soil aggregates, cracks, and earthworm burrow walls, the A/B ratios are relatively higher near a root residue and relatively lower near a quartz grain. The millimeter‐scale variability of OM composition obtained here by an in situ analysis of A/B ratios at structural surfaces seems promising for determination of locally distributed OM properties. The DRIFT mapping may improve understanding the development of soil structural properties, from which descriptions of preferential flow and transport may benefit.