bluuebunny/crossref_metadata_2025 huggingface dataset:
Ventral Mesencephalon-Enriched Genes That Regulate the Development of Dopaminergic NeuronsIn Vivo
Authors: Yin Min , Liu Shuxi , Yin Yanqing , Li Sen , Li Zhihua , Wu Xuefei , Zhang Bo , Ang Siew-Lan , Ding Yuqiang , Zhou Jiawei
Published: April 2009

Mesodiencephalic dopaminergic (mDA) neurons are critical for movement control and other physiological activities. However, the molecular mechanisms underlying their development are poorly understood. We aimed to establish the expression profiles of genes involved in this process and unravel genetic programs that control late development of mDA neurons. We compared genome-wide gene expression profiles of developing mouse ventral mesencephalon (VM) using microarrays. We identified a set of genes that show spatially and temporally restricted expression in the VM in anNgn2(neurogenin 2)-dependent manner and are potentially important for mDA neuron development. Functional analysis on mice lacking the VM-specific gene early B-cell factor 1 (Ebf1) revealed thatEbf1is essential for the terminal migration of mDA neurons in the substantia nigra pars compacta. Thus, we identified a set of VM-enriched genes that are important for mDA neuron development. Our analysis also provides a genetic framework for further investigation of the molecular mechanisms mediating mDA neuron development.
Expertise with Artificial Nonspeech Sounds Recruits Speech-Sensitive Cortical Regions
Authors: Leech Robert , Holt Lori L. , Devlin Joseph T. , Dick Frederic
Published: April 2009

Regions of the human temporal lobe show greater activation for speech than for other sounds. These differences may reflect intrinsically specialized domain-specific adaptations for processing speech, or they may be driven by the significant expertise we have in listening to the speech signal. To test the expertise hypothesis, we used a video-game-based paradigm that tacitly trained listeners to categorize acoustically complex, artificial nonlinguistic sounds. Before and after training, we used functional MRI to measure how expertise with these sounds modulated temporal lobe activation. Participants' ability to explicitly categorize the nonspeech sounds predicted the change in pretraining to posttraining activation in speech-sensitive regions of the left posterior superior temporal sulcus, suggesting that emergent auditory expertise may help drive this functional regionalization. Thus, seemingly domain-specific patterns of neural activation in higher cortical regions may be driven in part by experience-based restructuring of high-dimensional perceptual space.
Gap Junctions between Striatal Fast-Spiking Interneurons Regulate Spiking Activity and Synchronization as a Function of Cortical Activity
Authors: Hjorth Johannes , Blackwell Kim T. , Hellgren Kotaleski Jeanette
Published: April 2009

Striatal fast-spiking (FS) interneurons are interconnected by gap junctions into sparsely connected networks. As demonstrated for cortical FS interneurons, these gap junctions in the striatum may cause synchronized spiking, which would increase the influence that FS neurons have on spiking by the striatal medium spiny (MS) neurons. Dysfunction of the basal ganglia is characterized by changes in synchrony or periodicity, thus gap junctions between FS interneurons may modulate synchrony and thereby influence behavior such as reward learning and motor control. To explore the roles of gap junctions on activity and spike synchronization in a striatal FS population, we built a network model of FS interneurons. Each FS connects to 30–40% of its neighbors, as found experimentally, and each FS interneuron in the network is activated by simulated corticostriatal synaptic inputs. Our simulations show that the proportion of synchronous spikes in FS networks with gap junctions increases with increased conductance of the electrical synapse; however, the synchronization effects are moderate for experimentally estimated conductances. Instead, the main tendency is that the presence of gap junctions reduces the total number of spikes generated in response to synaptic inputs in the network. The reduction in spike firing is due to shunting through the gap junctions; which is minimized or absent when the neurons receive coincident inputs. Together these findings suggest that a population of electrically coupled FS interneurons may function collectively as input detectors that are especially sensitive to synchronized synaptic inputs received from the cortex.
Organization of Intralaminar and Translaminar Neuronal Connectivity in the Superficial Spinal Dorsal Horn
Authors: Kato Go , Kawasaki Yasuhiko , Koga Kohei , Uta Daisuke , Kosugi Masafumi , Yasaka Toshiharu , Yoshimura Megumu , Ji Ru-Rong , Strassman Andrew M.
Published: April 2009

The spinal dorsal horn exhibits a high degree of intrinsic connectivity that is critical to its role in the processing of nociceptive information. To examine the spatial organization of this intrinsic connectivity, we used laser-scanning photostimulation in parasagittal and transverse slices of lumbar spinal cord to stimulate presynaptic neurons by glutamate uncaging, and mapped the location of sites that provide excitatory and inhibitory synaptic input to neurons of the superficial laminae. Excitatory interneuronal connectivity within lamina II exhibited a pronounced sagittal orientation, in keeping with the somatotopic organization present in the pattern of primary afferent projections. Excitatory inputs to all classes of lamina II neurons arose from a wider rostrocaudal area than inhibitory inputs, whereas both excitatory and inhibitory input zones were restricted mediolaterally. Lamina I–II neurons exhibited cell type-specific patterns in the laminar distribution of their excitatory inputs that were related to their dorsoventral dendritic expanse. All cell types received excitatory input predominantly from positions ventral to that of their soma, but in lamina I neurons and lamina II vertical cells this ventral displacement of the excitatory input zone was greater than in the other cell types, resulting in a more pronounced translaminar input pattern. A previously unknown excitatory input to the superficial dorsal horn from lamina III–IV was identified in a subset of the vertical cell population. These results reveal a specific three-dimensional organization in the local patterns of excitatory and inhibitory connectivity that has implications for the processing of information related to both somatotopy and sensory modality.
Kein König im Palast. Heterodoxe Überlegungen zur politischen und sozialen Ordnung in der mykenischen ZeitNo King in the Palace. Heterodox Observations on the Political and Social Order in the Mycenaean Era
Authors: Schmitt Tassilo
Published: April 2009

Der Beitrag geht der Frage nach, wie gut die in der Forschung verbreitete Vorstellung begründet ist, daß die mykenischen Reiche unter der Herrschaft von Königen standen. Ausgangspunkt ist die vor einigen Jahren gemachte überraschende Beobachtung, daß eindeutige Zeichen einer monarchischen Repräsentation fehlen. Methodisch ergibt sich daraus nicht die Notwendigkeit, Erklärungen dafür zu suchen, warum ein Herrscher hier ohne Repräsentation auskommt, sondern zu überprüfen, ob es einen solchen Herrscher überhaupt gibt. Die Analyse archäologischer Befunde, die Interpretation einschlägiger Texte und Untersuchungen von Sprachentwicklungen und Sprachgebrauch führen zu dem Ergebnis, daß der meist als König angesprochene /wanax/ als ein Gott anzusehen ist. Der sogenannte Palast selbst erweist sich als Stätte kultischer und sozialer Interaktion, gerade nicht aber als politisches oder als Herrschaftszentrum. Insbesondere ist er in keiner Weise in die militärischen Angelegenheiten einbezogen, die für das politische Leben ebenso wie für das Selbstverständnis der mykenischen Eliten von wesentlicher Bedeutung waren.
Evaluation of an enzyme immunoassay for plasma-free metanephrines in the diagnosis of catecholamine-secreting tumors
Authors: Procopiou Michel , Finney Hazel , Akker Scott A , Chew Shern L , Drake William M , Burrin Jacky , Grossman Ashley B
Published: April 2009

Objective

To define the test characteristics of an enzyme immunoassay (EIA) for plasma-free metanephrines (metanephrine and normetanephrine) in the diagnosis of pheochromocytoma and paraganglioma.

Design

Prospective observational design from a single University Hospital. Twenty-four hour urine for catecholamines and plasma for free metanephrines were collected from patients with a clinical suspicion of pheochromocytoma or paraganglioma. Patient records were reviewed for clinical data, follow-up, imaging and laboratory results to establish or exclude the diagnosis of pheochromocytoma.

Patients and methods

Out of 178 consecutive patients, 10 had a paraganglioma and 12 had a pheochromocytoma: 156 were finally judged not to harbour active tumors and were therefore considered as controls. The main outcome measure was the diagnosis or exclusion of paraganglioma or pheochromocytoma and test characteristics of plasma-free metanephrines measured by EIA.

Results

Urinary epinephrine had a sensitivity of 45.5% and norepinephrine a sensitivity of 75% (98.8% specificity) for the diagnosis of pheochromocytoma. Plasma-free metanephrine and normetanephrine both had a sensitivity of 66.7% and a specificity of 100%, but when combined (either positive) they demonstrated a 91.7% sensitivity with a preserved specificity of 100%. For the diagnosis of paraganglioma, urinary norepinephrine gave slightly better results than plasma-free metanephrines, but combined testing was of no additional value.

Conclusions

Plasma-free metanephrines measured by EIA have better diagnostic test characteristics than urinary catecholamines in the diagnosis of pheochromocytoma. The EIA offers a simple and effective measurement of plasma-free metanephrines.
Revealing the bovine embryo transcript profiles during early in vivo embryonic development
Authors: Vallée Maud , Dufort Isabelle , Desrosiers Stéphanie , Labbe Aurélie , Gravel Catherine , Gilbert Isabelle , Robert Claude , Sirard Marc-André
Published: April 2009

Gene expression profiling is proving to be a powerful approach for the identification of molecular mechanisms underlying complex cellular functions such as the dynamic early embryonic development. The objective of this study was to perform a transcript abundance profiling analysis of bovine early embryonic developmentin vivousing a bovine developmental array. The molecular description of the first week of life at the mRNA level is particularly challenging when considering the important fluctuations in RNA content that occur between developmental stages. Accounting for the different intrinsic RNA content between developmental stages was achieved by restricting the reaction time during the global amplification steps and by using spiked controls and reference samples. Analysis based on intensity values revealed that most of the transcripts on the array were present at some point duringin vivobovine early embryonic development, while the varying number of genes detected in each developmental stage confirmed the dynamic profile of gene expression occurring during embryonic development. Pair-wise comparison of gene expression showed a marked difference between oocytes and blastocysts profiles, and principal component analysis revealed that the majority of the transcripts could be regrouped into three main clusters representing distinct RNA abundance profiles. Overall, these data provide a detailed temporal profile of the abundance of mRNAs revealing the richness of signaling processes in early mammalian development. Results presented here provide better knowledge of bovinein vivoembryonic development and contribute to the progression of our current knowledge regarding the first week of life in mammals.
Struvite infection calculi in dogs: problems with urinary calculus identification, and the value of the results
Authors: Dunlevey John , Laing Michael
Published: April 2009

Identifying the crystalline components of a urinary calculus is a valuable aid to correct diagnosis, and subsequent treatment of the underlying cause of the problem. Calculus formation is often an end product brought about by urine with a high concentration of insoluble material causing bladder irritation. This promotes bacterial infection by Proteus, which not only raises the pH in the bladder and generates ammonia, but also provides sites for mineral nucleation and crystal growth. Treating the infection and removing the stone will not necessarily cure the disorder. Correct identification of a calculus as struvite and even its potassium analogue can be critical in choice of curative protocols, but this is not always straightforward. Our experience with 'problem calculi' is described.
The first fossil of the Congo peafowl (Galliformes: Afropavo)
Authors: Stidham Thomas A.
Published: April 2009

A fossil from the Middle Stone Age internal deposits of Plovers Lake Cave in the Sterkfontein Valley, Gauteng province, South Africa, is the first fossil specimen that can be allocated to the Congo peafowl (Afropavo congensis), a species that is currently endemic to the Democratic Republic of Congo in central Africa. The fossil greatly extends the known geographic range of this rainforest taxon and suggests the presence of forested or even rainforest habitats near Plovers Lake Cave during the Middle Stone Age when the fossil was deposited. The presence of this central African taxon in South Africa implies that either its geographic range expanded during a period of climate change during the late Pleistocene or that its currently restricted distribution is a relict of a more extensive past distribution across a larger part of Africa.
Enhanced stabilization of collagen-based dermal regeneration scaffolds through the combination of physical and chemical crosslinking
Authors: Wessels Q.B. , Pretorius E.
Published: April 2009

The use of collagen in the biomedical device industry has led to major advances in soft tissue repair. This is attributed largely to the favourable biological and physiochemical properties of collagen. Regenerative medicine and tissue engineering favoured the use of this biomaterial and various commercial products have become available in the past few decades. This study aims to develop a collagen and chondroitin-6-sulphate dermal regeneration scaffold with enhanced resistance against enzymatic degradation. Frozen slurries (0.5% collagen) were dried under vacuum, coated with silicone, crosslinked and then thoroughly rinsed. The scaffolds were subjected to a range of quantitative and qualitative tests that included: scanning electron microscopy analysis, collagenase enzymatic degradation, and cytotoxicity assessment. Scaffold resistance to enzymatic degradation was manipulated after dehydrothermal treatment by employing combinations of crosslinking agents, such as glutaraldehyde and/or carbodiimide, with or without the presence of L-lysine. Results indicate that highly porous (mean pore diameter of 87.3 µm), bioactive, non-cytotoxic tissue engineering matrices were obtained. Enhanced stability of these scaffolds was achieved through extensive crosslinking and suggests the potential to prevent in vivo wound contraction sufficiently.
Global sugar, regional water, and local people: EU sugar regime liberalisation, rural livelihoods, and the environment in the Incomati River Basin
Authors: Lorentzen Jo
Published: April 2009

This paper is concerned with how changes in the global economy, triggered by actions undertaken in one part of the world, can affect the lives and the prospects of poor rural people, as well as the environment they live in, in another very distant part of the world. It analyses the linkages between changes in the European Union (EU) sugar regime and the economic fortunes and the environmental future of a very poor and highly water-stressed area in southern Africa—the Incomati River Basin—where sugar production is the single most important economic activity. The case study epitomises the complex interactions between trade liberalisation on the one hand and poverty and the environment on the other.
Preference for dry sex, condom use and risk of STI among HIV-negative black women in the Western Cape province, South Africa
Authors: Reddy Priscilla , Saleh-Onoya Dorina , Sifunda Sibusiso , Lang Delia , Wingood Gina , van den Borne Bart , Ruiter Robert A.C.
Published: April 2009

The practice of dry sex is reportedly common among young black women in South Africa. The aim of this study was to explore the relationship of women's preference for dry sex with condom use and the prevalence of Chlamydia trachomatis (CT), Neisseria gonorrhoea (NG) and Trichomonas vaginalis (TV) infections. Between January 2006 and December 2007, 446 women completed a behavioural survey in isiXhosa which assessed demographic information, sexual behaviours, condom use behaviour and other potential correlates. In total, 159 (36.72%) women indicated preferring dry sex. A multivariate logistic regression model indicated that participants who preferred dry sex were more likely to report past STI episodes and to have a partner who also preferred dry sex. The findings indicate that dry sex behaviour was not directly associated with condom use and STI (CT, NG, and TV) prevalence but may have been associated with relationships in which sexual preferences of the male partner were dominant.
Caracterização física de dois substratos orgânicos para plantas e a estimativa da umidade por meio da reflectometria no domínio do tempo
Authors: Valero Roger Manuel Mestas , Matsura Edson Eiji , Souza Anderson Luiz de
Published: April 2009

O crescente uso de substratos na produção agrícola e no cultivo em ambiente protegido, promove produção em grande escala. Nesse sentido, as caracterizações químicas, biológicas e físicas desses materiais se fazem necessárias à proposição e à avaliação de padrões de qualidade que devem preceder a sua comercialização. As propriedades físicas dos substratos influenciam no bom desenvolvimento da plantas, sobretudo, no manejo de irrigação, onde a compreensão da relação retenção de água e aeração é imprescindível. Para tanto, mostra-se necessário que também se determine o volume de água presente nos substratos utilizados. Nesse sentido, o uso da reflectometria no domínio do tempo (TDR) pode representar um avanço em estudos dessa natureza. Dessa forma, baseado na determinação das curvas de retenção de água, neste trabalho, foram feitas as caracterizações físicas de dois substratos orgânicos: casca de pinus e fibra de coco. Também foram ajustadas, para cada um dos substratos avaliados, uma curva de calibração, através da qual, por meio da técnica da TDR, estimou-se o seu conteúdo de água. De maneira geral, com exceção da densidade seca, os substratos em estudo apresentaram características físicas da relação ar-água muito semelhantes. Quando comparado com os valores obtidos pelo método gravimétrico, na faixa de água facilmente disponível, a técnica da TDR apresentou um bom desempenho na estimativa da umidade de ambos substratos apresentando um coeficiente de determinação de 0,9319 para a casca de pinus e de 0,9385 para a fibra de coco.
Environmental approach of companies within the pulp/paper, metallurgical and sugar/alcohol sectors
Authors: Jacovine Laércio Antônio Gonçalves , Viana Wellerson David , Alves Ricardo Ribeiro , Walter Michele Karina Cotta , Silva Márcio Lopes da , Valverde Sebastião Renato
Published: April 2009

Companies have been witnessing major changes in their environment and environmental models have been developed aiming to improve their strategic planning. The objective of this study was to examine the environmental approach adopted by companies within the Pulp and Paper, Metallurgical and Sugar and Alcohol sectors, in order to evaluate their environmental performances. The analysis was based on a matrix which relates managerial functions with a set of environmental approaches and performance indicators, classifying the company environmental performance as weak, moderate or strong. The managerial functions approached in this model are: Management (General, Legal Affairs, Finance, Human Resources and Purchasing); Product and Process Development; Production and Maintenance; and Marketing. The analyzed indicators include: international insertion; capital origin and location. The pulp and paper and metallurgical companies obtained average scores of 54.5 and 51.56 points, respectively, being classified as having a strong environmental performance. On the other hand, the sugar and alcohol companies obtained average score of 46 points, being classified as moderate in environmental performance. The high level of environmental performance of pulp and paper and metallurgical companies can be attributed to the following factors: larger international insertion, presence of foreign capital in controlling shares, performance in the international market and company location near large population centers. Pulp and paper and mainly sugar and alcohol companies are less efficient in meeting the requirements of the environmental legislation, particularly those related to the conformity of permanent protected areas and legal reserves.
Standards for associations and alliances of the U.S. National Vegetation Classification
Authors: Jennings Michael D. , Faber-Langendoen Don , Loucks Orie L. , Peet Robert K. , Roberts David
Published: April 2009

This article provides guidelines for the description, documentation, and review of proposals for new or revised plant associations and alliances to be recognized as units of vegetation within the U.S. National Vegetation Classification (NVC). By setting forth standards for field records, analysis, description, peer review, and archiving, the Ecological Society of America's Vegetation Classification Panel, in collaboration with the U.S. Federal Geographic Data Committee, NatureServe, and others, seeks to advance our common understanding of vegetation and improve our capability to sustain and restore natural systems. We provide definitions for the two floristic levels of the NVC hierarchy: associations and alliances. This is followed by a description of standards for field plot records and the identification and classification of vegetation types. Procedures for review and evaluation of proposed additions and revisions of types are provided, as is a structure for data archiving and dissemination. These procedures provide a dynamic and practical way to publish new or revised descriptions of vegetation types while maintaining a current, authoritative list of types for multiple users to access and apply.
A geographic selection mosaic in a generalized plant–pollinator–herbivore system
Authors: Gómez J. M. , Perfectti F. , Bosch J. , Camacho J. P. M.
Published: April 2009

The concept of Selection Mosaic is central to the Geographic Mosaic Theory of Coevolution. Most information on coevolving interactions, however, comes from specialized organisms. In contrast, an accurate understanding of the effect of geographically varying evolutionary dynamics on the evolution of generalist organisms is lacking, although these kinds of organisms are the most frequent in nature. In flowering plants, pollinators and herbivores are important selective agents. In this study we investigate whether a geographic selection mosaic for floral traits in a generalist plant,Erysimum mediohispanicum(Brassicaceae), can be mediated by the interplay of mutualistic and antagonistic interacting organisms. In eight populations we quantified the selection exerted by these organisms on several plant traits. We found significant spatial variation in pollinator assemblage. In different populations, the main pollinators belonged to different functional groups (beeflies, large bees, small bees, and beetles). Damage by ungulates also varied among populations. Consequently, we found that different populations were under different selective regimes, and the traits affected by selection depended on the local interaction intensity with pollinators and mammal herbivores. Some traits, such as flower number and stalk height, were selected similarly in most populations. Other traits, such as corolla diameter and tube length, were selected only in some populations. Finally, we found divergent selection for some traits, such as corolla tube width and corolla shape, which were selected in contrasting directions in different localities. This spatial variation in selective scenarios results in populations with strong selective regimes (hot spots) intermingled with populations with weak selective regimes (cold spots). Four important outcomes emerge from theE. mediohispanicumselection mosaic. (1) Interactions with generalist organisms may produce strong selection. (2) Spatial changes in main pollinators result in divergent selection across populations. (3) Geographic mosaics depend on a balance between mutualistic and antagonistic selection. (4) Selection mosaics operate at fairly small spatial scales. These findings will surely contribute to expanding the conceptual framework of the Geographic Mosaic Theory of Coevolution.
Defoliation and patchy nutrient return drive grazing effects on plant and soil properties in a dairy cow pasture
Authors: Mikola J. , Setälä H. , Virkajärvi P. , Saarijärvi K. , Ilmarinen K. , Voigt W. , Vestberg M.
Published: April 2009

Large herbivores can influence plant and soil properties in grassland ecosystems, but especially for belowground biota and processes, the mechanisms that explain these effects are not fully understood. Here, we examine the capability of three grazing mechanisms—plant defoliation, dung and urine return, and physical presence of animals (causing trampling and excreta return in patches)—to explain grazing effects inPhleum pratense–Festuca pratensisdairy cow pasture in Finland. Comparison of control plots and plots grazed by cows showed that grazing maintained original plant‐community structure, decreased shoot mass and root N and P concentrations, increased shoot N and P concentrations, and had an inconsistent effect on root mass. Among soil fauna, grazing increased the abundance of fungivorous nematodes andAporrectodeaearthworms and decreased the abundance of detritivorous enchytraeids andLumbricusearthworms. Grazing also increased soil density and pH but did not affect average soil inorganic‐N concentration. To reveal the mechanisms behind these effects, we analyzed results from mowed plots and plots that were both mowed and treated with a dung and urine mixture. This comparison revealed that grazing effects on plant attributes were almost entirely explained by defoliation, with only one partly explained by excreta return. Among belowground attributes, however, the mechanisms were more mixed, with effects explained by defoliation, patchy excreta return, and cow trampling. Average soil inorganic‐N concentration was not affected by grazing because it was simultaneously decreased by defoliation and increased by cow presence. Presence of cows created great spatial heterogeneity in soil N availability and abundance of fungivorous nematodes. A greenhouse trial revealed a grazing‐induced soil feedback on plant growth, which was explained by patchiness in N availability rather than changes in soil biota. Our results show that grazing effects on plant attributes can be satisfactorily predicted using the effects of defoliation, whereas those on soil fauna and soil N availability need understanding of other mechanisms as well. The results indicate that defoliation‐induced changes in plant ecophysiology and the great spatial variation in N availability created by grazers are the two key mechanisms through which large herbivores can control grassland ecosystems.
Modeling Soil Flux by Manual Tillage as a Nonlinear Slope‐Dependent Process
Authors: Ziegler Alan D. , Sutherland Ross A.
Published: April 2009

A review of seven studies addressing soil flux related to manual hoeing and weeding in Asia and Africa indicates that tillage erosion from hand‐held implements on steep hillslopes can alter topography and influence the distribution of soil and nutrients within fields. Soil flux resulting from manual tillage increases with slope in a near‐linear fashion until the slope angle approaches the angle of repose for displaced aggregates. On steeper slope gradients, the increase in soil flux is nonlinear because displaced clods roll, bounce, or slide relatively long distances downslope before coming to rest or breaking down. Because of this ravel‐like transport process, soil flux is modeled most appropriately across a wide range of gradients as a nonlinear process. A modified nonlinear ravel model predicted soil fluxes in the reviewed studies better than a linear model, but it was not superior to a general exponential model. Additional field studies are needed to increase the basic understanding and predictability of soil erosion by manual tillage on steep slopes, as this activity is still practiced in many areas of the world.
Calculating the Effect of Soil Organic Matter Concentration on Soil Bulk Density
Authors: Ruehlmann Joerg , Körschens Martin
Published: April 2009

Soil bulk density (ρb) is required to estimate, evaluate, and calculate many physical soil properties and processes and is essential to convert data from weight‐based to volume‐ and area‐related data. One of the dominating factors changing ρb is the soil's organic matter (SOM) concentration that alters the soil's compressibility; ρb is an important soil structure attribute. Currently, no parameter for characterizing soil compactness giving directly comparable values for all soils is available. Therefore, our aim was to develop a general approach to calculate the effect of SOM concentration on ρb that would be universally valid for soils different in their genesis, compaction, and type of land use. To describe the effect of SOM on ρb mathematically, we used a nonlinear regression model that was parameterized and validated using published data from experiments where SOM concentration was the main ρb–affecting factor (long‐term fertilization and proctor experiments, wetlands, reclaimed soils, and volcanic soils). To obtain a standardized parameter describing the present compaction status of a site, we introduced the standardized bulk density sρb Mathematically, sρb is the intercept parameter of the used nonlinear regression model, and ranged between 0.7 and 2.1 Mg m−3 and was very simple to estimate. Another distinct advantage of this novel concept is that only one representative pair of ρb and SOM has to be known to calculate sρb as well as the bulk densities corresponding to other SOM concentrations measured on the site. This concept might also be helpful for identifying similar universal approaches to standardize the effect of other ρb affecting parameters (e.g., texture, soil depth, tillage regime), however, reassessed from the SOM effect.
Spatial and Temporal Distributions in Sandy Soils with Seepage Irrigation: II. Phosphorus and Potassium
Authors: Sato Shinjiro , Morgan Kelly T. , Ozores-Hampton Monica , Simonne Eric H.
Published: April 2009

Fertilizer management, particularly of P and K, on sandy soils is crucial to maximize production and minimize environmental impact in agricultural systems. Experiments were conducted at commercial tomato (Lycopersicon esculentum Mill.) farms in southwest Florida during the 2006 spring and winter growing seasons to elucidate P and K distributions in tomato beds and to determine leaching potential under seepage irrigation. Most P was found in the top (0–10 cm) and middle (10–20 cm) soil layers at the centerline (plant row) of the soil bed, and P concentration remained relatively constant. Phosphorus in the bottom layer (20–30 cm) and bed shoulder were similar or less than preplant levels, implying that P did not likely move outside the root zone. However, P fractionation and soil P storage capacity (SPSC) of the root zone samples revealed higher risk of P loss when applied P remained more in soil solution. Most K remained in the top layer of the fertilizer band in an order of magnitude higher concentration compared with the rest of the bed, where low and constant amounts of K were found throughout the season. This result indicated that little or no K leached during this study. Seepage irrigation may have limited downward water movement in the bed, thus nutrient leaching, therefore nutrient loss through surface runoff between growing seasons could be substantial. Current Best Management Practices (BMP) for tomato fertilization should be monitored and evaluated.
Plantation Management Intensity Affects Belowground Carbon and Nitrogen Storage in Northern California
Authors: McFarlane Karis J. , Schoenholtz Stephen H. , Powers Robert F.
Published: April 2009

Belowground C and N storage is important in maintaining forest productivity and to CO2 sequestration. How these pools respond to management is poorly understood. We investigated effects of repeated applications of complete fertilizer and competing vegetation control with herbicides on C and N storage in forest‐floor, fine‐root, and mineral‐soil C and N pools to 1‐m depth at three Pinus ponderosa P. Lawson & C. Lawson var. ponderosa plantations across a site quality gradient in northern California. Belowground C pools without treatment were 66, 153, and 199 Mg C ha−1 for the low‐, intermediate‐, and high‐quality sites, respectively, and N pools were 5.1, 6.7, and 6.5 Mg N ha−1, respectively. Treatments increased tree‐bole volume at 20 yr as much as 400%, while changes in C and N pools belowground were less dramatic. Herbicide treatment increased forest‐floor C pools 35% at the poorer quality site. Fertilization increased forest‐floor C and N storage 46 to 106% at all sites. Fertilization decreased fine‐root C pools at 0 to 0.3 m at the most productive site 43% and increased this N pool 43% at the least productive site, but did not influence fine‐root pools to 1 m. Fertilization increased mineral‐soil C pools on lower quality sites, resulting in 12 to 57% more belowground C storage. At the intermediate site, fertilization increased total belowground N storage 12%. Results of this study suggest that the major sequestration mechanism up to this point in stand development is through gains in tree biomass rather than storage in fine roots and soil belowground.
Complex Permittivity Model for Time Domain Reflectometry Soil Water Content Sensing: I. Theory
Authors: Schwartz R. C. , Evett S. R. , Pelletier M. G. , Bell J. M.
Published: April 2009

Despite numerous applications of time‐domain reflectometry (TDR), serious difficulties remain in estimating accurate soil water contents under field conditions, especially in fine‐textured soils. We developed a physically based calibration model to predict the frequency‐ and temperature‐dependent complex dielectric response of soils. The model was used to predict frequency‐dependent attenuation and a single “effective” frequency approximation of apparent permittivity of the soil. Effective frequency was predicted to decline from 450 to 160 MHz as water contents increased from air dry to saturation. Predicted frequency decline was small for an input bandwidth of 130 MHz, reflecting that modeled polarization mechanisms associated with relaxation frequencies above 100 MHz were responsible for most of the frequency‐dependent attenuation. For specific surface areas ranging from 150 to 300 m2 g−1, simulations indicate that ignoring dielectric and conductive losses or the associated decline in effective frequency results in a 5 to 22% underestimation of the apparent permittivity. Both the power‐law and de Loor–Dobson mixing models gave a reasonable approximation to the measured apparent permittivity for a silty clay loam (34% clay) across the entire water content range. Moreover, the models were able to describe the behavior of apparent permittivity in response to temperature for two soils with contrasting bulk electrical conductivity contributions to losses. These results demonstrate that loss mechanisms and declines in effective frequency need to be considered to accurately predict the soil water content of fine‐textured soils.
Crop‐Residue‐Derived Char Influences Sorption, Desorption and Bioavailability of Atrazine in Soils
Authors: Loganathan Vijay A. , Feng Yucheng , Sheng G. Daniel , Clement T. Prabhakar
Published: April 2009

The bioavailability of pesticides in soils is affected by the addition of crop‐residue‐derived char, which alters the sorption and desorption characteristics of the soils. Sorption, desorption, and biodegradation experiments were performed using atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] as the target compound in two soils (Hartsells and Grady) with and without a wheat (Triticum aestivum L.) char, and the char alone. The sorption isotherms for both soils were highly linear, whereas the isotherms for 1% char‐amended soils showed an increased sorption capacity and isotherm nonlinearity. The amount of atrazine sorbed by the char alone was 800 to 3800 times greater than sorbed by the soils. Successive desorption experiments showed that char‐amended soils contained higher nondesorbable fractions of atrazine than soils without char amendment. Pseudomonas sp. strain ADP capable of rapidly mineralizing atrazine was used to evaluate atrazine bioavailability. The presence of char reduced 14CO2 production by 11 and 20% in the char‐amended soils and char, respectively. The two‐step successive desorption experiments appeared to be able to predict the bioavailabilty of atrazine in char‐amended soils. This study shows that the presence of char in soils significantly influences the sorption and desorption processes and, ultimately, the bioavailability of atrazine.
Enhancing Carbon and Nitrogen Sequestration in Reclaimed Soils through Organic Amendments and Chiseling
Authors: Shrestha Raj K. , Lal Rattan , Jacinthe Pierre-Andre
Published: April 2009

The choice of reclamation techniques could affect restoration success, ecosystem productivity, and the capacity of reclaimed mine soil (RMS) to sequester soil organic carbon (SOC). A field experiment was conducted at three reclaimed coal mine sites across eastern Ohio to assess the impact of several reclamation techniques on biomass production, soil properties, and temporal changes in SOC and N pools. Amendments and reclamation practices tested were: normal reclamation practice (NRP, control), cow (Bos taurus) manure (10 Mg ha−1), mulching with oat straw (15 Mg ha−1), and chiseling (30‐cm depth). At each site, all treatments were applied in triplicate to experimental plots in accord with a randomized complete block design. After 5 yr of restoration, results showed no effect of mulching on any of the soil properties investigated but significant effects of manuring and chiseling. During that period, SOC sequestration rates ranged between 0.6 and 2.8 Mg C ha−1yr−1, with the highest rates recorded in the manure‐treated plots. Aboveground biomass production, biomass N content, and soil N and SOC pools were also significantly higher in the manure and chiseling treatments, probably due to greater exploration of the soil volume by plant roots and more efficient uptake of water and available nutrients. Ecosystem C (SOC + biomass C) in these two treatments also exceeded that in the NRP by 25 to 27 Mg C ha−1Thus, manure application and chiseling are effective reclamation practices for restoring RMS and enhancing C sequestration in these ecosystems.
Characterization of the Organic Nitrogen Fraction Determined by the Illinois Soil Nitrogen Test
Authors: Kwon Ho-Young , Hudson Robert J. M. , Mulvaney Richard L.
Published: April 2009

The Illinois soil nitrogen test (ISNT) has shown promise as a predictor of corn (Zea mays L.) response to N fertilization in several field trials, but controversy has arisen regarding whether the test detects a particular class of organic N compounds or a constant fraction of the organic N in agricultural soils (SON). The goal of this study is to elucidate the chemical properties of the ISNT‐labile N and its relationship to microbial growth in agricultural soils. In the ISNT, NH3 generated during alkaline hydrolysis of whole soil samples is separated from the hydrolysate by diffusion and quantified by trapping and acidimetric titration. Analyses of pure organic N compounds confirmed that the ISNT detects the N in some components of microbial biomass, such as the monomeric amino sugars (AS) of bacterial cell walls (95% recovery) and amides (AM, 55% of monomers), but not α amino acids (αAA) or chitin (CTN), a refractory AS polymer. Because the ISNT detects different proportions of these N containing compounds than any other conventional acid hydrolyzable SON fraction, ISNT‐N can be considered a fifth fraction that together with the others permits one to distinguish AS of bacterial and fungal origin. Using this approach, the average proportions of SON components observed in 10 manured (and 16 non‐manured) agricultural soils from Illinois are 18% (10%) CTN, 11% (5%) bacterial amino sugars (BAS), 10% (17%) AM, 29% (25%) αAA, and 15% (20%) unknown. The reason that the sum of CTN and BAS is 50% greater than the conventional AS N fraction (AS‐N) of these soils—18% (9.5%) of SON—is the lack of recovery correction conventionally made to AS‐N data. To investigate N fractions in living biomass, we conducted studies of 15NH4+ immobilization in two fresh soils. ISNT‐N was more rapidly labeled than AS‐N, a fact that is indicative of more rapid labeling of bacteria than fungi. Taken together, these findings suggest that the effectiveness of the ISNT for predicting corn N response is due largely to its ability to quantify N in BAS. Because ISNT also detects some AM‐N, the BAS‐N signal may be obscured in soil N datasets where these components are highly variable.
Waste composts as nitrogen fertilizers for forage leys
Authors: TONTTI T. , NYKÄNEN A. , KUISMA M.
Published: April 2009

Two field experiments, conventional grass ley and organic grass-clover ley, were established with barley as a nurse crop in spring 2000 and given either low or high fertilization with mineral fertilizer (Mineral) or composts. The compost types were municipal biowaste (Biowaste), biowaste + sewage sludge (BioSludge) and cattle manure (Manure). Plant yields and nitrogen (N) uptakes were measured for three years and efficiency of N utilization was estimated. In single application of compost, the total N was mainly in organic form and less than 10% was in inorganic form. Along with increasing amount of inorganic N applied in compost, the yield, N uptake and N recovery increased during the application year. The highest compost N recovery in the application year was 12%, found with Biowaste. In the following years the highest N recovery was found where the lowest total N had been applied. Clover performance was improved in the organic grass-clover ley established with BioSludge fertilization, producing total ley yield comparable with Manure compost. High total N application in composts caused high N surplus and low N use efficiency over three years. Generally, moderate compost fertilization is suitable for ley crops when supplemented with mineral N fertilizer or clover N fixation.;
Winter triticale yield formation and quality affected by N rate, timing and splitting
Authors: ALARU M. , LAUR Ü. , EREMEEV V.
Published: April 2009

The field experiment was conducted to study the effects different nitrogen (N) quantities (N0120 kg ha-1) and application regimes (N applied at stages of tillering BBCH2830 and flag leaf sheath opening BBCH47) on (i) the formation of winter triticale above ground biomass (AGB), (ii) the grain yield (iii) the yield quality, and also (iiii) to find more suitable N fertilizing regimes for winter triticale depending on their utilization. Winter rye and winter wheat were used as reference crops. The efficiency of applying all N at the tillering stage (N100%+N0) was the highest for the grain yield of triticale. N application at development stage of plants BBCH47 increased the grain protein concentration significantly and the increase by 1 kg N was the highest in triticale cultivars. More stabile grain yield was produced by triticales in application regime N+N. N splitting did not influence significantly either the duration of the grain-filling period or the dry matter accumulation rate of triticale. N splitting affected Hagberg falling number (HFN) indirectly through the effect on the grain yield formation and grain protein concentration. HFN was positively correlated with the grain yield and negatively with the grain protein concentration. The suitable N regimes are: 1) triticale as the energy plant  N60+N0  N applied at the tillering stage of plants and suitable N norm is not more than 60 kg N ha-1; 2) triticale as a feed or food  N60+N60  High grain yield, protein and lysine concentration level are assured then.;
Getting Serious about Job Creation: Part I
Authors: Edlin Aaron S. , Phelps Edmund
Published: April 2009

The ideal economic stimulus would be something that should be done in any event --- making work pay with employee tax credits --- according to Aaron Edlin and Edmund Phelps.
Environmental and Pro-Social Norms: Evidence on Littering
Authors: Torgler Benno , Frey Bruno S. , Wilson Clevo
Published: April 2009

The paper investigates the relationship between pro-social norms and its implications for improved environmental outcomes. This is an area, which has been neglected in the environmental economics literature. We provide empirical evidence to demonstrate a small but significant positive impact between perceived environmental cooperation (reduced public littering) and increased voluntary environmental morale. For this purpose we use European Values Survey (EVS) data for 30 European countries. We also demonstrate that Western European countries are more sensitive to perceived environmental cooperation than the public in Eastern Europe. Interestingly, the results also demonstrate that environmental morale is strongly correlated with several socio-economic and environmental variables. Several robustness tests are conducted to check the validity of the results.
The Socioeconomic Gap in University Dropouts
Authors: Vignoles Anna F , Powdthavee Nattavudh
Published: April 2009

In many countries, including the U.S. and the U.K., there is ongoing concern about the extent to which young people from lower-income backgrounds can acquire a university degree. Recent evidence from the U.K. suggests that for a given level of prior achievement in secondary school a disadvantaged student has as much chance of enrolling in a university as a more advantaged student. However, simply participating in higher education is not sufficientgraduation is important. Therefore, this paper investigates whether students from lower socioeconomic backgrounds have a higher rate of university dropout when compared to their wealthier counterparts, allowing for their differential prior achievement. Using a combination of school and university administrative data sets, we show that there is indeed a sizeable and statistically significant gap in the rate of withdrawal after the first year of university between advantaged and disadvantaged English students. This socioeconomic gap in university dropouts remains even after allowing for their personal characteristics, prior achievement in secondary school and university characteristics. In the English context, at least, this implies that retention in university of disadvantaged students is arguably a more important policy issue than barriers to entry for these students.
Gestational Diabetes Mellitus: Developments in Diagnosis and Treatment
Authors: Fraser Robert
Published: April 2009

After many years of uncertainty regarding the true pathological nature of mild gestational diabetes and the possible benefits of treatment, the situation appears to have been resolved by the publication of the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS). It is now appropriate for obstetric units to review their treatment and screening programs for gestational diabetes mellitus. Furthermore, with the publication of the Metformin in Gestational Diabetes (MiG) trial, consideration should be given as to whether metformin should be the first choice when diet fails to maintain glycemic control.