bluuebunny/crossref_metadata_2025 huggingface dataset:
Breadth and intensity: Salient, separable, and developmentally significant dimensions of structured youth activity involvement
Authors: Busseri Michael A. , Rose‐Krasnor Linda
Published: January 2009

In recent years, an impressive volume of evidence has accumulated demonstrating that youth involvement in structured, organized activities (e.g. school sports, community clubs) may facilitate positive youth development. We present a theory‐based framework for studying structured activity involvement (SAI) as a context for positive youth development based on two key dimensions: breadth and intensity of involvement. Our main goal is to demonstrate the separability, salience, and developmental significance of these two dimensions. We review three developmental theoretical approaches (identity development, life‐span selection–optimization–compensation theory, and affordances) that support our conceptualization of breadth and intensity as salient and significant dimensions of SAI. We also summarize our recent program of research on SAI demonstrating the separability of breadth and intensity dimensions, which shows links between these dimensions and indicators of positive development. Finally, we discuss how the proposed breadth‐intensity approach could be used to extend research on the linkage between youth SAI and successful development.
Listening comprehension in preschoolers: The role of memory
Authors: Florit Elena , Roch Maja , Altoè Gianmarco , Levorato Maria Chiara
Published: January 2009

The current study analyzed the relationship between text comprehension and memory skills in preschoolers. We were interested in verifying the hypothesis that memory is a specific contributor to listening comprehension in preschool children after controlling for verbal abilities. We were also interested in analyzing the developmental path of the relationship between memory skills and listening comprehension in the age range considered. Forty‐four, 4‐year‐olds (mean age = 4 years and 6 months, SD =4 months) and 40, 5‐year‐olds (mean age = 5 years and 4 months, SD =5 months) participated in the study. The children were administered measures to evaluate listening comprehension ability (story comprehension), short‐term and working memory skills (forward and backward word span), verbal intelligence and receptive vocabulary. Results showed that both short‐term and working memory predicted unique and independent variance in listening comprehension after controlling for verbal abilities, with working memory explaining additional variance over and above short‐term memory. The predictive power of memory skills was stable in the age range considered. Results also confirm a strong relation between verbal abilities and listening comprehension in 4‐ and 5‐year‐old children.
Return of the Candy Witch: Individual differences in acceptance and stability of belief in a novel fantastical being
Authors: Boerger Elizabeth A. , Tullos Ansley , Woolley Jacqueline D.
Published: January 2009

Recent research indicates that preschoolers make sophisticated choices in accepting testimony as a source of knowledge. Nonetheless, many children accept fantastical beings as real based on misleading testimony. The present study probes factors associated with belief in a novel fantastical figure, the Candy Witch, that 3‐ to 7‐year‐olds heard about at school. Short‐term belief was predicted by an interaction of age, existing beliefs in fantastical figures, and whether the child was ‘visited’ by the Candy Witch. Stability of belief was assessed over the course of 3 weeks and again 1‐year later. First year results revealed three patterns of belief: stable belief, wavering belief and stable non‐belief. First year belief status was not related to age, but older children from the stable belief group were more likely than younger children to disbelieve 1‐year later. The discussion presents a new proposal for the trajectory from belief to disbelief and an updated perspective on the role of individual differences in belief.
Predicting children's media use in the USA: Differences in cross‐sectional and longitudinal analysis
Authors: Lee Sook‐Jung , Bartolic Silvia , Vandewater Elizabeth A.
Published: January 2009

The purpose of this paper is to examine the predictors of children's media use in the USA, comparing cross‐sectional and longitudinal analyses. Data come from Waves 1 and 2 of the Child Development Supplement (CDS‐I; CDS‐II), a nationally representative sample of American children aged 0–12 in 1997 and 5–18 in 2002. Twenty‐four hour time use diaries are used to assess children's time spent with media (television, video games, computers, and reading). Predictors examined include socio‐demographics, neighbourhood quality, family factors, and other media use. Ordinary least square (OLS) multiple regressions were performed by three age groups (preschoolers, early school age, and preadolescence). The findings suggest that neighbourhood quality, parental limits and family conflict are significant predictors of children's media use within time or over time, but the significance depends on the type of media and child's developmental stage. In addition, children's television viewing and reading habits are formed early in life and reinforced over time. This study is among the first to provide empirical evidence for the effect of early contextual factors on the life course of children's media use from a developmental perspective.
The role of deception in P300 memory detection
Authors: Verschuere Bruno , Rosenfeld J. Peter , Winograd Michael R. , Labkovsky Elena , Wiersema Roeljan
Published: January 2009

Purpose. P300 memory detection test is a neuroscientific procedure to assess memories stored in the brain. P300 memory detection can and is currently applied to assess criminal suspects on recognition of critical crime information. Contrasting memory detection with lie detection, researchers have argued that P300 memory detection does not involve deception. We empirically investigated this argument by manipulating deception between groups.

Methods. Thirty‐four community volunteers participated in a P300 memory detection test, answering either deceptively (deceptive condition) or truthfully (truth condition) to their own name.

Results. P300 memory detection was significant in the truth condition, indicating that deceptive responding is not a prerequisite for valid P300 memory detection. However, there were clear indications that deceptive responding improved memory detection.

Conclusions. Deception seems involved in the P300 memory detection test; and deceptive responding may add to test accuracy.
Metaphors of organ donation, social representations of the body and the opt‐out system
Authors: Lauri Mary Anne
Published: January 2009

Organ donation is the only available treatment for end‐stage failure of organs such as liver, lung, and heart and therefore increasing the number of organ donors is a priority for most countries. One measure that could be taken by a country to increase the number of organ transplants is to introduce the opt‐out system of organ donation. Public opinion is divided on this issue and policy makers need to tread with caution before introducing legislation. This paper proposes that understanding the social representations the public has of organ donation is important in taking the right policy decisions. We propose here that an in‐depth study of the views held by people on the issue is essential in this regard and that this can best be done by investigating the metaphors people use to describe organ donation, interpreted within the theory of social representation. In this study, the social representations of organ donation were investigated through five focus groups with 57 participants living in Malta. Analysis of the transcriptions of these focus groups yielded pertinent issues related to organ donation. Moreover, metaphors of organ donations and how these were related to social representations of the body and attitudes towards the opt‐out system are discussed. It is being suggested that these findings could be of relevance to the present discussion on the opt‐out system in the UK and in other countries.
Codifying the Law on Evidential Burdens
Authors: Glover Richard
Published: January 2009

This article examines the concept of the evidential burden and argues that the decision in R v Malinina illustrates that the concept of the evidential burden is in desperate need of clarification. It will be contended that, ultimately, codification would be the best means of achieving that end.
Characterization of the Mechanisms Involved in the Increased Renal Elimination of Bromosulfophthalein During Cholestasis: Involvement of Oatp1
Authors: Brandoni Anabel , Torres Adriana Mònica
Published: January 2009

The kidneys and liver are the major routes for organic anion elimination. We have recently shown that acute obstructive jaundice is associated with increased systemic and renal elimination of two organic anions, p-aminohippurate and furosemide, principally excreted through urine. This study examined probable adaptive mechanisms involved in renal elimination of bromosulfophthalein (BSP), a prototypical organic anion principally excreted in bile, in rats with acute obstructive jaundice. Male Wistar rats underwent bile duct ligation (BDL rats). Pair-fed sham-operated rats served as controls. BSP renal clearance was performed by conventional techniques. Renal organic anion-transporting polypeptide 1 (Oatp1) expression was evaluated by immunoblotting and IHC. Excreted, filtered, and secreted loads of BSP were all higher in BDL rats compared with Sham rats. The higher BSP filtered load resulted from the increase in plasma BSP concentration in BDL rats, because glomerular filtration rate showed no difference with the Sham group. The increase in the secreted load might be explained by the higher expression of Oatp1 observed in apical membranes from kidneys of BDL animals. This likely adaptation to hepatic injury, specifically in biliary components elimination, might explain, at least in part, the huge increase in BSP renal excretion observed in this experimental model. (J Histochem Cytochem 57:449–456, 2009)
Effects of Cooling Rate Fluctuation on Cooling and Transformation Behavior of Steel upon Direct Quenching
Authors: Luo Xinmin , Li Jiankang
Published: January 2009

TTT-diagrams and CCT-diagrams, which are derived from isothermal Newtonian cooling conditions, have been traditionally used for developing and examining heat treating processes. However, actual cooling and transformation behavior of a steel part upon direct quenching is controlled by a number of factors. When examining actual quenching practice, it is important to correlate cooling performance of the quenchant and the cooling and transformational behavior of steel, especially if there is a variation of cooling rate during the quenching process. This behavior is very difficult to detect by a cooling curve method only. Theoretically, dynamic measurement may be used to detect any transient, even a very small variance in thermoelectric potential. Thus, measurement of thermoelectric potential may provide more detail and insight into the quenching process than a simple temperature-time response as reflected by conventional cooling curve analysis. Therefore, to detect dynamic cooling and steel transformation behavior upon direct quenching, an experiment was conducted using plain carbon steel rods of ⊘5–8 mm diameter with a thermocouple located at the geometric center of the bar. Cooling rate variation upon direct quenching was characteristically demonstrated by dynamic cooling curves. The smaller the diameter of the rods, the more drastic the quench severity and the more sensitive the cooling curve. By comparison to an appropriate temperature-time-transformation (TTT)-diagram or continuous cooling transformation (CCT)-diagram, the cooling process and the transformation behavior of steel upon direct quenching was analyzed with respect to the cooling rate fluctuation obtained in this experiment. The presence of lamellar pearlite of 0.70 % carbon steel wire substantiated the effects of cooling methods and quenchant on the cooling and transformation behavior of the steel wire upon direct quenching. Dynamic measurements revealed new and helpful details related to the direct quenching process.
The structural properties of amides and imides as hydrogen storage materials
Authors: Ichikawa Takayuki , Isobe Shigehito
Published: January 2009

We discuss crystal structure of amides and imides, which are focusing on promising hydrogen storage materials. They are ionic crystal with anion of (NH2)– or (NH)2– and cation of Li+, Na+, Mg2+, Ca2+, and so forth. We also discuss reaction mechanisms on hydrogen ab/desorption of amide/imide hydrogen storage materials.
RicePi5-Mediated Resistance toMagnaporthe oryzaeRequires the Presence of Two Coiled-Coil–Nucleotide-Binding–Leucine-Rich Repeat Genes
Authors: Lee Sang-Kyu , Song Min-Young , Seo Young-Su , Kim Hye-Kyung , Ko Seho , Cao Pei-Jian , Suh Jung-Pil , Yi Gihwan , Roh Jae-Hwan , Lee Sichul , An Gynheung , Hahn Tae-Ryong , Wang Guo-Liang , Ronald Pamela , Jeon Jong-Seong
Published: January 2009

Rice blast, caused by the fungus Magnaporthe oryzae, is one of the most devastating diseases of rice. To understand the molecular basis of Pi5-mediated resistance to M. oryzae, we cloned the resistance (R) gene at this locus using a map-based cloning strategy. Genetic and phenotypic analyses of 2014 F2 progeny from a mapping population derived from a cross between IR50, a susceptible rice cultivar, and the RIL260 line carrying Pi5 enabled us to narrow down the Pi5 locus to a 130-kb interval. Sequence analysis of this genomic region identified two candidate genes, Pi5-1 and Pi5-2, which encode proteins carrying three motifs characteristic of R genes: an N-terminal coiled-coil (CC) motif, a nucleotide-binding (NB) domain, and a leucine-rich repeat (LRR) motif. In genetic transformation experiments of a susceptible rice cultivar, neither the Pi5-1 nor the Pi5-2 gene was found to confer resistance to M. oryzae. In contrast, transgenic rice plants expressing both of these genes, generated by crossing transgenic lines carrying each gene individually, conferred Pi5-mediated resistance to M. oryzae. Gene expression analysis revealed that Pi5-1 transcripts accumulate after pathogen challenge, whereas the Pi5-2 gene is constitutively expressed. These results indicate that the presence of these two genes is required for rice Pi5-mediated resistance to M. oryzae.
Cystic fibrosis and pregnancy
Authors: Goddard Julie , Bourke Stephen J
Published: January 2009

Cystic fibrosis is the most common inherited life‐threatening disease.

Advances in treatment have led to increased life expectancy.

Increasing numbers of women with cystic fibrosis are choosing to embark on pregnancy; for most, it does not appear to have a detrimental effect on long‐term health.

Pregnancy outcomes are generally good but 20% of women do not live to see their child's tenth birthday.

Learning objectives:

To be aware of the effects of cystic fibrosis on pregnancy.

To understand the importance of preconceptual counselling.

To appreciate that pregnancy management requires a multidisciplinary approach.

Ethical issues:

Should doctors advise women with cystic fibrosis and poor lung function against undertaking pregnancy?

Should assisted reproductive technology be available for women with life‐limiting diseases?

Please cite this article as: Goddard J, Bourke SJ. Cystic fibrosis and pregnancy. The Obstetrician & Gynaecologist 2009;11:19–24.
Surrogate pregnancy: an essential guide for clinicians
Authors: Bhatia Kalsang , Martindale Elizabeth A , Rustamov Oybek , Nysenbaum Anthony M
Published: January 2009

The incidence of surrogacy is rising.

Literature on associated obstetric risks is scarce and caution must be exercised when labelling surrogate pregnancies as low risk.

Although obstetricians’ responsibilities lie with the surrogate mother, they must ensure her wishes do not conflict with the best interests of the baby.

Prepregnancy counselling is the key to a successful surrogacy arrangement.

Learning objectives:

To gain an awareness of the different types of surrogacy.

To understand the law surrounding surrogacy.

To learn about antenatal, intrapartum and postpartum care in surrogacy.

Ethical issues:

When the surrogate mother's wishes and the interests of the child conflict, do obstetricians have the right to discuss this with the commissioning parents without her consent?

When should obstetricians seek ethical and legal support?

Please cite this article as: Bhatia K, Martindale EA, Rustamov O, Nysenbaum AM. Surrogate pregnancy: an essential guide for clinicians. The Obstetrician & Gynaecologist 2009;11:49–54.
Multiprofessional ‘fire‐drill’ training in the labour ward
Authors: Siassakos Dimitrios , Crofts Joanna , Winter Cathy , Draycott Timothy ,   on behalf of the SaFE Study Group
Published: January 2009

Regular multiprofessional rehearsals of the management of obstetric emergencies have been recommended since 1997.

In‐house training is cheap and associated with improved outcomes.

Teamwork failure is associated with poor obstetric outcome but aviation‐based team training is not a panacea: we may need to develop and evaluate obstetric‐specific interventions.

Learning objectives:

To comprehend the importance of rehearsals in the labour ward.

To understand the components of successful ‘fire‐drills’.

Ethical issues:

Excessive focusing on the processes of training can lead to neglect of teamworking and prevent sustainable differences in outcomes.

Entrenched negative attitudes to risk management processes can reduce the impact of training.

Please cite this article as: Siassakos D, Crofts J, Winter C, Draycott T. Multiprofessional ‘fire‐drill’ training in the labour ward. The Obstetrician & Gynaecologist 2009;11:55–60.
Corticosteroid receptors, macrophages and cardiovascular disease
Authors: Rickard Amanda J , Young Morag J
Published: January 2009

The mineralocorticoid receptor (MR) and glucocorticoid receptor are ligand-activated transcription factors that have important physiological and pathophysiological actions in a broad range of cell types including monocytes and macrophages. While the glucocorticoids cortisol and corticosterone have well-described anti-inflammatory actions on both recruited and tissue resident macrophages, a role for the mineralocorticoid aldosterone in these cells is largely undefined. Emerging evidence, however, suggests that MR signalling may promote pro-inflammatory effects. This review will discuss the current understanding of the role of corticosteroid receptors in macrophages and their effect on diseases involving inflammation, with a particular focus on cardiovascular disease.
Changes in gut hormone levels and negative energy balance during aerobic exercise in obese young males
Authors: Ueda Shin-ya , Yoshikawa Takahiro , Katsura Yoshihiro , Usui Tatsuya , Nakao Hayato , Fujimoto Shigeo
Published: January 2009

We examined whether changes in gut hormone levels due to a single bout of aerobic exercise differ between obese young males and normal controls, and attempted to determine the involvement of hormonal changes during exercise in the regulation of energy balance (EB) in these obese subjects. Seven obese and seven age-matched subjects of normal weight participated in exercise and rest sessions. Subjects consumed a standardized breakfast that was followed by constant cycling exercise at 50% VO2max or rest for 60 min. At lunch, a test meal was presented, and energy intake (EI) and relative energy intake (REI) were calculated. Blood samples were obtained at 30 min intervals during both sessions for measurement of glucose, insulin, glucagon, ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1). Plasma levels of PYY and GLP-1 were increased by exercise, whereas plasma ghrelin levels were unaffected by exercise. The areas under the curve (AUC) of the time courses of PYY and GLP-1 levels did not significantly differ between the two groups. In contrast, EI and REI were decreased by exercise in both groups, and energy deficit was significantly larger in obese subjects than in normal controls. The present findings suggest that short-term EB during a single exercise session might be regulated not by increased amounts of these gut hormones per se.
Nature and origin of the Triassic volcanism in Albania and Othrys: a key to understanding the Neotethys opening?
Authors: Monjoie Philippe , Lapierre Henriette , Tashko Artan , Mascle Georges H. , Dechamp Aline , Muceku Bardhyl , Brunet Pierre
Published: January 2009

Triassic volcanic rocks, stratigraphically associated with pelagic or reef limestones, are tectonically juxtaposed with Mesozoic ophiolites in the Tethyan realm. From the central (Dinarides, Hellenides) and eastern Mediterranean (Antalya, Troodos, Baër Bassit) to the Semail nappes (Oman), they occur either associated to the tectonic sole of the ophiolitic nappes or as a distinct tectonic pile intercalated between the ophiolites and other underthrust units. In the Dinaro-Hellenic belt, the Pelagonian units represent the lower plate, which is underthrust beneath the ophiolites. Middle to Late Triassic volcanic sequences are interpreted as the eastern flank of the Pelagonian platform and are therefore considered as a distal, deep-water part of the Pelagonian margin.

The Triassic volcanics from Albania and Othrys are made up of basaltic pillowed and massive flows, associated locally with dolerites and trachytes. New elemental, Nd and Pb isotopic data allow to recognize four types of volcanic suites: (1) intra-oceanic alkaline and tholeiitic basalts, (2) intra-oceanic arc-tholeiites, (3) back-arc basin basalts, (4) calc-alkaline mafic to felsic rocks. Nd and Pb isotopic initial ratios suggest that the within-plate volcanic rocks were derived from an enriched oceanic island basalt type mantle source, devoid of any continental crustal component. The lower εNd value of the trachyte could be due to assimilation of oceanic altered crust or sediments in a shallow magma chamber. Island arc tholeiites and back-arc basin basalts have a similar wide range of εNd. The absence of Nb negative anomalies in the back-arc basin basalts suggests that the basin floored by these basalts was wide and mature. The high Th contents of the island arc tholeiites suggest that the arc volcanoes were located not far away from the continental margin.

Albania and Othrys volcanics contrast with the Late Triassic volcanism from eastern Mediterranean (SW Cyprus, SW Turkey), which displays solely features of oceanic within plate suites. The presence of back-arc basin basalts associated with arc-related volcanics in Central Mediterranean indicates that they were close to a still active subduction during the Upper Triassic, while back-arc basins developed, associated with within-plate volcanism, leading to the NeoTethys opening.
Carbon Dioxide and Nitrous Oxide Fluxes in Corn Grown under Two Tillage Systems in Southwestern Quebec
Authors: Almaraz Juan J. , Mabood Fazli , Zhou Xiaomin , Madramootoo Chandra , Rochette Philippe , Ma Bao-Luo , Smith Donald L.
Published: January 2009

Agriculture has an important potential role in mitigating greenhouse gas emissions (GHG). However, practices that reduce CO2 emissions from soils and increase the soil organic C level may stimulate N2O emissions. This is particularly critical in Quebec where heavy soils and a humid climate may limit the adoption of agricultural practices designed to mitigate GHG. The objective of this work was to study the effects of two tillage and N fertilization regimes on CO2 and N2O fluxes and the seasonal variability in emissions of these gases, associated with corn (Zea mays L.) grown in southwestern Quebec. Different seasonal emission patterns of CO2 and N2O were observed. Higher N2O fluxes occurred during the spring and were associated with precipitation events, while higher CO2 fluxes occurred in mid‐season and were related to temperature. Conventional tillage (CT) had greater peaks of CO2 emissions than no‐till (NT) only after disking in the spring. Once corn was established, differences between tillage systems were small. Peaks of N2O emission occurred in both systems (NT and CT) following N application. Plots receiving 180 kg N ha−1 in both tillage systems had large peak of N2O emission rates during the wettest parts of the season. The CT and NT systems generally had similar cumulative CO2 emissions but NT had higher cumulative N2O emissions than CT. Our findings suggests that changing from CT to NT under the heavy soil conditions of Quebec may increase GHG, mainly as result of the increase in N2O emission. This negative effect of NT could be reduced by avoiding fertilizing when precipitation is more intense.
Continuing Acidification of Organic Soils across the Northeastern USA: 1984–2001
Authors: Warby Richard A. F. , Johnson Chris E. , Driscoll Charles T.
Published: January 2009

We conducted a resurvey of the O horizon in 2001 in watersheds previously sampled in 1984 under the Direct/Delayed Response Program (DDRP) to evaluate the effects of reductions in acidic deposition in the northeastern United States. In this 17‐yr interval, median base saturation in the Oa horizon decreased from 56.2% in 1984 to 33.0% in 2001. Effective cation exchange capacity (CECe), normalized to soil C concentration, showed no significant change between 1984 and 2001. The change in base saturation was the result of almost equivalent changes in C‐normalized exchangeable Ca (CaN) and exchangeable Al (AlN). The median CaN declined by more than 50%, from 23.5 to 10.6 cmolc kg−1 C, while median AlN more than doubled, from 8.8 to 21.3 cmolc kg−1 C. We observed the greatest change in soil acid–base properties in the montane regions of Central New England (CNE) and Maine, where base saturation decreased by more than 50% and median soil pH in 0.01 M CaCl2 (pHs) decreased from 3.19 to 2.97. Changes in median concentrations of other exchangeable cations were either statistically insignificant (MgN, KN) or very small (NaN). We observed no significant change in the median values of either total soil C content (%C) or total soil N content (%N) over the 17‐yr interval. The acidification of the Oa horizon between 1984 and 2001 occurred despite substantial reductions in atmospheric acidic deposition. Our results may help to explain the surprisingly slow rate of recovery of surface waters.
Organic Matter and Water Stability of Field Aggregates Affected by Tillage in South Dakota
Authors: Pikul Joseph L. , Chilom Gabriela , Rice James , Eynard Anna , Schumacher Thomas E. , Nichols Kristine , Johnson Jane M. F. , Wright Sara , Caesar TheCan , Ellsbury Michael
Published: January 2009

Tillage has been associated with soil organic matter (SOM) decline. A case study of two adjacent farms was conducted in eastern South Dakota. One farm used no‐till (NT) and the other used chisel tillage (CT). We hypothesized that soil under NT, compared with tillage, would have both greater quantity and greater quality of SOM and that this improved SOM condition would result in increased water stable aggregation (WSA). A rotary sieve was used to sort dry field aggregates into six size groups: <0.4, 0.4 to 0.8, 0.8 to 2.0, 2.0 to 6.0, 6.0 to 19.0, and >19 mm. Water stable aggregation, soil organic C (SOC), N, glomalin, and basidiomycete fungi were measured. Fine particulate soil organic matter (fPOM, 0.5–0.053 mm) and coarse particulate organic matter (2.0–0.5 mm) were isolated by sieving. Quantitative solid‐state13C nuclear magnetic resonance was used to determine C type in humic acid, humin, and whole soil. The fPOM/SOM ratio was greatest in <0.4‐mm aggregates and 24% greater in NT than CT. Soil organic C was greatest in 0.8‐ to 2.0‐mm aggregates and 11% greater in NT than CT. Average WSA was 63% greater under NT than under CT. Aggregate wettability was less under NT than CT. Slower water uptake under NT might be attributed to a greater abundance of wax‐type C under NT than under CT. We conclude that NT, compared with CT, resulted in better SOM quality during the course of 10 yr. Improved SOM quality was related to improved WSA.
Soil Bulk Electrical Conductivity Measurement using High‐Dielectric Coated Time Domain Reflectometry Probes
Authors: Moret-Fernández D. , Merino R. I. , Lera F. , López M. V. , Arrúe J. L.
Published: January 2009

Time domain reflectometry (TDR) is a technique that allows simultaneous estimates of apparent permittivity (εa) and hence volumetric water content (θ) and bulk electrical conductivity (σa). Difficulties arise for θ and σa determination, however, when uncoated TDR probes (UP) are used in highly conductive media. This work shows that σa can be estimated in highly conductive media using a TDR probe coated with a high‐dielectric insulator (CP). To this end, the Dalton method for σa estimations was applied to a 10‐cm‐long three‐rod TDR probe insulated with a 0.2‐mm‐thick epoxy‐ceramic composite coating with a relative permittivity, εr, of 32.3. This method was calibrated on different NaCl–water solutions (0–15 dS m−1) and compared with the standard long‐time TDR method for σa estimations using an UP. The method was subsequently used for determining σa in four different soils with different values of θ and σa (0–6 dS m−1) and again compared with the standard TDR procedure. The low error (RMSE = 1.5) for the comparison between the εa measured with the CP and that calculated with the analytical solution for coaxial probes indicates that the CP is accurate enough for εa estimations. For σa values <4 dS m−1, the UP allows determinations of εa and the most accurate estimations of σa using the standard TDR method (R2 = 0.99). For higher σa values, however, estimations of εa were only possible using the CP, where σa was satisfactorily determined (R2 = 0.99) using the Dalton method. To this end, a previous calibration between the real and the apparent bulk electrical conductivity estimated with the CP was required.
Characterization of Structural Profiles in Clay‐Rich Marsh Soils by Cone Resistance and Resistivity Measurements
Authors: Bernard-Ubertosi M. , Dudoignon P. , Pons Y.
Published: January 2009

The management of clay‐rich soils in agriculture is mainly dependent on their hydromechanical properties that govern their structural evolutions. These structural evolutions are commonly described along the shrinkage curves obtained in a laboratory. Nevertheless, the field survey needs tools of in situ investigations able to characterize the structural profile evolutions of soils through the seasons. This paper presents a method based on the cone penetration and resistivity measurement by penetrometer–salinometer coupling that was gauged in the West Marsh of the French Atlantic Coast. First, the parallel measurements of water and cone resistance (Qd ) profiles in clay dominant soils, characterized by very large ranges of water content (W), allows the calculation of a Perdock's‐type equation that links the Qd profiles and the shrinkage curve of the clay dominant material. Second, thanks to the homogeneity of mineralogy and cationic exchange capacity of the soil, the structure–resistivity relationship was gauged according to the Archie's law taking into account porosity (ϕ), saturation index of the soil (Sat), and the resistivity of the wetting fluid (ρw). The vertical evolutions of structure, resistivity, and cone resistance can be represented in a crossed diagram showing the shrinkage curve–resistivity and Qd profile relationships. Finally, the structural profiles of soils can be modeled from the recorded resistivity and Qd profiles taking into account the ρw
Fungal and Bacterial Abundance in Long‐Term No‐Till and Intensive‐Till Soils of the Northern Great Plains
Authors: Helgason Bobbi L. , Walley Fran L. , Germida James J.
Published: January 2009

Abundance of fungi and bacteria in long‐term no‐till (NT) and intensively tilled (IT) soils in the Northern Great Plains were measured using phospholipid fatty acid analysis (PLFA) to determine if a shift in the relative abundance of fungi and bacteria occurs as the result of conversion to NT. Four tillage trials located in four different soil zones were sampled in spring of 2005 and 2006 before the crop was seeded to evaluate the long‐term effect of tillage on the microbial community. With the exception of one site‐year, total, bacterial, and fungal PLFA were greater in NT than IT soils at the soil surface (0‐ to 5‐cm depth) (p < 0.05). Increases ranged from 8 to 202% for total biomass, 26 to 58% for bacterial biomass, and 0 to 120% for fungal biomass. At one site (Ellerslie) all biomass measurements were greater in IT than NT in 2005 and bacterial biomass was also greater under IT in 2006. The influence of tillage on microbial biomass was less pronounced with depth. Fungal dominance is commonly assumed under NT; however, our results demonstrate that although biomass of both fungi and bacteria increase in NT, the abundance of fungi vs. bacteria was not consistently greater under NT in the soils studied. Further research is needed to determine if fungi may be able to exert a more functionally dominant role in NT soils without an increase in relative abundance.
Interactive Effects of Tillage and Mineral Fertilization on Soil Carbon Profiles
Authors: Poirier Vincent , Angers Denis A. , Rochette Philippe , Chantigny Martin H. , Ziadi Noura , Tremblay Gilles , Fortin Josée
Published: January 2009

Both tillage and fertilizer management influence soil organic C (SOC) storage, but their interactive effects remain to be determined for various soil and climatic conditions. We evaluated the long‐term effects of tillage (no‐till, NT, and moldboard plowing, MP), and N and P fertilization on SOC stocks and concentrations in profiles of a clay loam soil (clayey, mixed, mesic Typic Humaquept). Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] were grown in a yearly rotation for 14 yr. Our results showed that NT enhanced the SOC content in the soil surface layer, but MP resulted in greater SOC content near the bottom of the plow layer. When the entire soil profile (0–60 cm) was considered, both effects compensated each other, which resulted in statistically equivalent SOC stocks for both tillage practices. Nitrogen and P fertilization with MP increased the estimated crop C inputs to the soil but did not significantly influence SOC stocks in the whole soil profile. At the 0‐ to 20‐cm depth, however, lower C stocks were measured in the plowed soil with the highest N fertilizer level than in any other treatment, which was probably caused by a greater decomposition of crop residues and soil organic matter. Conversely, the highest SOC stocks of the 0‐ to 20‐cm soil layer were observed in the NT treatment with the highest N rates, reflecting a greater residue accumulation at the soil surface. When accounting for the whole soil profile, the variations in surface SOC due to tillage and fertilizer interactions were masked by tillage‐induced differences in the 20‐ to 30‐cm soil layer.
Modeling of Soil Organic Carbon Fractions Using Visible–Near‐Infrared Spectroscopy
Authors: Vasques Gustavo M. , Grunwald Sabine , Sickman James O.
Published: January 2009

There is a pressing need for rapid and cost‐effective tools to estimate soil C across larger landscapes. Visible–near‐infrared diffuse reflectance spectroscopy (VNIRS) offers comparable levels of accuracy to conventional laboratory methods for estimating various soil properties. We used VNIRS to estimate soil total organic C (TC) and four organic C fractions in 141 samples collected in the Santa Fe River watershed of Florida. The C fractions measured were (in order of decreasing potential residence time in soils): recalcitrant C (RC), hydrolyzable C (HC), hot‐water‐soluble C (SC), and mineralizable C (MC). Soil samples were scanned in the visible–near‐infrared spectral range. Six preprocessing transformations were applied to the soil reflectance, and five multivariate techniques were tested to model soil TC and the organic C fractions: stepwise multiple linear regression (SMLR), principal components regression, partial least squares regression (PLSR), regression tree, and committee trees. Total organic C was estimated with the highest accuracy, obtaining a coefficient of determination using a validation set (Rv2) of 0.86, followed by RC (Rv2 = 0.82), both using PLSR. The SC fraction was modeled best by SMLR (Rv2 = 0.70), while PLSR produced the best models of MC (Rv2 = 0.65) and HC (Rv2 = 0.40). The addition of TC as a predictor improved the VNIRS models of the soil organic C fractions. Our study indicates the suitability of VNIRS to quantify soil organic C pools with widely varying turnover times in soils, which are important in the context of C sequestration and climate change.
Free Iron Oxide Determination in Mediterranean Soils using Diffuse Reflectance Spectroscopy
Authors: Richter N. , Jarmer T. , Chabrillat S. , Oyonarte C. , Hostert P. , Kaufmann H.
Published: January 2009

Soil Fe oxides occur in almost all soils and reflect different environmental conditions by the high variability of their mineralogy and concentration. Quantitatively determining this important pedogenic indicator enables diffuse reflectance spectroscopy (DRS) based on material‐specific absorption characteristics. This paper presents a methodology that directly links free Fe oxide content (Fed, citrate‐dithionite extractable Fe) with the diagnostic Fe absorption band near 900 nm (Fe‐NIR). In addition, we investigated the influence of soil texture on the spectral characteristics and prediction accuracy. We showed that the Fe absorption bands of clay‐dominated soil samples were, in general, deeper than sand‐dominated samples with comparable Fedcontent. Based on the Fe‐NIR absorption depth, we created two texture‐dependent Fedprediction models, retrieving the best Fedestimates for the sand calibrated model (R2v= 0.87, rel. MSEv= 13.9%). Due to the high texture variability in sand, silt, and clay fractions of the clay–silt dominated samples, the clay–silt calibrated model produced good predictions (R2v= 0.70, rel. RMSEv= 19.0%). The soil texture appeared to have no significant influence on model stability but did affect the prediction accuracy. Constant Fedcontents were over‐ and underestimated when applying the texture‐dependent models to other texture groups. The texture‐independent model was stable and performed well (R2v= 0.76, rel. RMSEv= 18.1%). These results are highly relevant to the subsequent spatial assessment of free Fe oxide content as an indicator for soil development from hyperspectral remote sensing data.
Clay, Organic Matter, and Wetting Effects on Splash Detachment and Aggregate Breakdown under Intense Rainfall
Authors: Wuddivira Mark N. , Stone Reynold J. , Ekwue Edwin I.
Published: January 2009

The binding and cementing potentials of clay and organic matter (OM) and the weakening effect of wetting are important in the stability of soil aggregates. They can therefore influence aggregate breakdown (AB) and splash detachment (SD), which are initial steps in the erosion process. We investigated the interactive effects of clay and OM on AB and SD under various wetting rates (WR) and antecedent moisture contents (AMC) using six agricultural soils from Trinidad. The selection criteria for the six soils were based on three levels of clay; low (<20%), medium (20–45%) and high (>45%) and two levels of OM; low (≤3%), and high (>3%). Samples were prewetted with mist at slow (7.5 mm h−1) and fast (75 mm h−1) WR to AMC of 0.5 of field capacity (FC) and FC and exposed to intense simulated rainfall of 120 mm h−1 The sensitivity of a sample to disruption under varying wetting conditions and intense rainfall depended on the level of combination of clay and OM in the sample. Increase in clay beyond the medium level without raising OM to high level strengthened disruptive forces and increased the proportion of microaggregates. The AB and SD of the medium clay‐high organic matter (McHom) soils were significantly lower than their high clay‐low organic matter (HcLom) counterparts irrespective of WR and AMC. This implies that a threshold clay content exists beyond which an accompanying increase in OM is required to mitigate detachment mechanisms and erosion under intense rainfall.
Comparing the EM38DD and DUALEM‐21S Sensors for Depth‐to‐Clay Mapping
Authors: Saey T. , Simpson D. , Vermeersch H. , Cockx L. , Van Meirvenne M.
Published: January 2009

Geophysical instruments show great potential for the detailed quantification of soil stratigraphy. In this study, two electromagnetic induction sensors were evaluated on their capacity to map small‐scale variations of the depth to the interface (zin) in a two‐layered soil. On a 2‐ha study site,zinbetween the silty topsoil and the contrasting clayey subsoil was modeled first by relating the two apparent electrical conductivity (ECa) measurements of the EM38DD sensor to observations ofzinobtained by augering. A substantial number of these calibration observations was needed, however, to account for the modeling parameters. To avoid this step, an entirely noninvasive procedure was proposed based on one survey with the DUALEM‐21S sensor. This sensor simultaneously records four ECavalues with different coil configurations. These measurements correspond to four different depth response functions that allow modelingzinwithout calibration observations. The only assumption was a two‐layered soil profile. Thezinpredictions were validated with 24 independent depth observations. Both procedures resulted in equal correlation coefficients (0.85) between predicted and measuredzinand average estimation errors (0.26 m). This indicated that both sensors allowed the accurate mapping of the depth to a contrasting textural layer. With the EM38DD, calibration observations are needed, whereas the four different coil conurations of the DUALEM‐21S sensor provided sufficient information to predict the interface depth without augering.
The Academic Impact of Financial Stress on College Students
Authors: Joo So-Hyun , Durband Dorothy Bagwell , Grable John
Published: January 2009

Staying in school and graduating on time is an important factor for students and their families. Greater financial burdens may lead students to reduce coursework or drop out of school for paid work. A Web-based survey ( N = 503) was conducted in fall 2004 at a large public university to examine the characteristics of students who experienced dropping out or reducing credit hours due to financial reasons. Analyses were conducted to compare these students with those who did not drop out or reduce their coursework. Findings show the relationship between financial stress and academic performance.
Hispanic Students and the Gates Millennium Scholarship Program: Promising Results Extending to the Third College Year
Authors: Oseguera Leticia , Denson Nida , Hurtado Sylvia
Published: January 2009

Financing college is increasingly difficult for many college students and it can be especially difficult for low-income students. Using data from the Gates Millennium Scholarship Program, this study provides a portrait of the 1st and 3rd year experiences of a sample of both high achieving Hispanic scholarship recipients and non-recipients. Applying Nora, Barlow, and Crisp's Student/Institution Engagement Theoretical Model (2005), we show how freedom from the stressors of paying for college enables students to become more engaged in academics and campus leadership activities even as we control for equally high levels of ability and involvement prior to college entry.
Academic-Centered Peer Interactions and Retention in Undergraduate Mathematics Programs
Authors: Callahan Kadian M.
Published: January 2009

Peer interactions are a critical component of students' academic success and retention in undergraduate programs. Scholars argue that peer interactions influence students' cognitive development, identity development, self-confidence and self-efficacy, and social and academic integration into the university environment (Pascarella & Terenzini, 1980, 1991, 2005). Research shows that reasonable levels of social interactions along with interactions that are academically-centered support students' persistence in undergraduate study (Bank, Slavings, & Biddle, 1990; Liu & Liu, 2000; Loo & Rolison, 1986). While both social and academic interactions among students shape undergraduate learning experiences, these interactions can differentially influence students' academic success and retention in undergraduate education. This study examined the ways first-year students supported their academic success in undergraduate mathematics-based programs by exploring the types of academic-centered peer interactions (ACPIs) in which students engaged both inside and outside of the classroom setting, and the relationship between participation in ACPIs to retention in undergraduate mathematics-based programs.
Bio‐Economics of Large‐Scale Eradication of Feral Goats From Santiago Island, Galápagos
Authors: CRUZ FELIPE , CARRION VICTOR , CAMPBELL KARL J. , LAVOIE CHRISTIAN , DONLAN C. JOSH
Published: January 2009

ABSTRACT  Invasive mammals are premier drivers of extinction and ecosystem change, particularly on islands. In the 1960s, conservation practitioners started developing techniques to eradicate invasive mammal populations from islands. Larger and more biologically complex islands are being targeted for restoration worldwide. We conducted a feral goat (Capra hircus) eradication campaign on Santiago Island in the Galápagos archipelago, which was an unprecedented advance in the ability to reverse biodiversity impacts by invasive species. We removed >79,000 goats from Santiago Island (58,465 ha) in <4.5 years, at an approximate cost of US$6.1 million. An eradication ethic combined with a suite of techniques and technologies made eradication possible. A field‐based Geographic Information System facilitated an adaptive management strategy, including adjustment and integration of hunting methods. Specialized ground hunting techniques with dogs removed most of the goat population. Aerial hunting by helicopter and Judas goat techniques were also critical. Mata Hari goats, sterilized female Judas goats induced into a long‐term estrus, removed males from the remnant feral population at an elevated rate, which likely decreased the length and cost of the eradication campaign. The last 1,000 goats cost US$2.0 million to remove; we spent an additional US$467,064 on monitoring to confirm eradication. Aerial hunting is cost‐effective even in countries where labor is inexpensive. Local sociopolitical environments and best practices emerging from large‐scale, fast‐paced eradications should drive future strategies. For nonnative ungulate eradications, island size is arguably no longer the limiting factor. Future challenges will involve removing invasive mammals from large inhabited islands while increasing cost‐effectiveness of removing low‐density populations and confirming eradication. Those challenges will require leveraging technology and applying theory from other disciplines, along with conservation practitioners working alongside sociologists and educators.