bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating finite difference block equivalent hydraulic conductivity for numerically solving the Richards' equation
Authors: Feng Chih‐Yung , Lee Tim Hau , Lee Wen Sen , Chen Chu‐Hui 
Published: September 2007

AbstractA method is proposed for calculating the equivalent hydraulic conductivity (EHC) within a finite difference block (FDB). Application of the constant‐flux assumption of Darcy's Law, the EHC equals to the integration of effective hydraulic conductivity (Kw) as a function of pressure head (hw) divided by the head difference at the ends of the FDB. Error analysis show that the constant‐flux (CF) EHC estimates are better than those computed by the commonly used arithmetic‐mean (AM), geometric‐mean (GM), and harmonic‐mean (HM) techniques. CF EHC results are even more superior at larger interblock head difference situations.Simulations of water infiltration experiments show that simulations using the CF EHC or AM or GM weighting technique have only slight difference while applying the Neumann type boundary condition at the ground surface. In case of the Dirichlet type boundary condition, however, the CF EHC is superior to the other two in correctly estimating the depth of infiltration while enlarging the grid size. Therefore, it is recommended to adopt the CF EHC with a larger grid size to the more stable and more efficient results. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of snow models in terrestrial biosphere models using ground observation and satellite data: impact on terrestrial ecosystem processes
Authors: Ichii Kazuhito , White Michael A. , Votava Petr , Michaelis Andrew , Nemani Ramakrishna R. 
Published: September 2007

AbstractSnow is important for water management, and an important component of the terrestrial biosphere and climate system. In this study, the snow models included in the Biome‐BGC and Terrestrial Observation and Prediction System (TOPS) terrestrial biosphere models are compared against ground and satellite observations over the Columbia River Basin in the US and Canada and the impacts of differences in snow models on simulated terrestrial ecosystem processes are analysed. First, a point‐based comparison of ground observations against model and satellite estimates of snow dynamics are conducted. Next, model and satellite snow estimates for the entire Columbia River Basin are compared. Then, using two different TOPS simulations, the default TOPS model (TOPS with TOPS snow model) and the TOPS model with the Biome‐BGC snow model, the impacts of snow model selection on runoff and gross primary production (GPP) are investigated. TOPS snow model predictions were consistent with ground and satellite estimates of seasonal and interannual variations in snow cover, snow water equivalent, and snow season length; however, in the Biome‐BGC snow model, the snow pack melted too early, leading to extensive underpredictions of snow season length and snow covered area. These biases led to earlier simulated peak runoff and reductions in summer GPP, underscoring the need for accurate snow models within terrestrial ecosystem models. Copyright © 2007 John Wiley & Sons, Ltd.
The application of electrical conductivity as a tracer for hydrograph separation in urban catchments
Authors: Pellerin Brian A. , Wollheim Wilfred M. , Feng Xiahong , Vörösmarty Charles J. 
Published: September 2007

AbstractTwo‐component hydrograph separation was performed on 19 low‐to‐moderate intensity rainfall events in a 4·1‐km2 urban watershed to infer the relative and absolute contribution of surface runoff (e.g. new water) to stormflow generation between 2001 and 2003. The electrical conductivity (EC) of water was used as a continuous and inexpensive tracer, with order of magnitude differences in precipitation (12–46 µS/cm) and pre‐event streamwater EC values (520–1297 µS/cm). While new water accounted for most of the increased discharge during storms (61–117%), the contribution of new water to total discharge during events was typically lower (18–78%) and negatively correlated with antecedent stream discharge (r2 = 0·55, p < 0·01). The amount of new water was positively correlated with total rainfall (r2 = 0·77), but hydrograph separation results suggest that less than half (9–46%) of the total rainfall on impervious surfaces is rapidly routed to the stream channel as new water. Comparison of hydrograph separation results using non‐conservative tracers (EC and Si) and a conservative isotopic tracer (δD) for two events showed similar results and highlighted the potential application of EC as an inexpensive, high frequency tracer for hydrograph separation studies in urban catchments. The use of a simple tracer‐based approach may help hydrologists and watershed managers to better understand impervious surface runoff, stormflow generation and non‐point‐source pollutant loading to urban streams. Copyright © 2007 John Wiley & Sons, Ltd.
Cyclin D1/cdk4 can interact with E2F4/DP1 and disrupts its DNA‐binding capacity
Authors: Scimè Anthony , Li Lili , Ciavarra Gianni , Whyte Peter 
Published: September 2007

AbstractThe E2F family of transcription factors regulate the expression of many growth‐related genes in a cell cycle‐dependent manner. These transcription factors can activate or, in conjunction with an Rb‐related protein, repress transcription. E2F transcriptional activity is regulated at several different levels that are each linked to cell cycle progression. In many cell types, E2F4 and E2F5 are the predominant E2F species during G0 and early G1 and function primarily as repressors of E2F‐regulated genes. In this study, co‐immunoprecipitation techniques were used to demonstrate that cyclins D1, D2, and D3 are capable of interacting with E2F4, E2F5, and DP1. Overexpression of cyclin D1/cdk4 reduced E2F4‐mediated transcription in a simple reporter gene assay and electrophoretic mobility shift analyses using nuclear extracts from transfected cells indicated that cyclin D1/cdk4 disrupts the DNA‐binding ability of E2F4. Cell cycle analysis following stimulation of serum‐starved 3T3 cells indicated that E2F4 undergoes changes in its phosphorylation pattern coincident with the synthesis of cyclin D1. Examination of a series of E2F4 deletion mutants indicated that a cyclin D1‐binding site located close to the carboxyl terminus of E2F4 was critical for the disruption of DNA binding by cyclin D1/cdk4. These data support a model in which E2F4 DNA binding is abolished during mid‐G1 at the same time when E2F interactions with pRb‐related proteins are disrupted by cyclin D1/cdk4. J. Cell. Physiol. 214: 568–581, 2008. © 2007 Wiley‐Liss, Inc.
The MAP kinase JNK‐1 of Caenorhabditis elegans: Location, activation, and influences over temperature‐dependent insulin‐like signaling, stress responses, and fitness
Authors: Wolf Marc , Nunes Frank , Henkel Arne , Heinick Alexander , Paul Rüdiger J. 
Published: September 2007

AbstractThe mitogen‐activated protein kinase (MAPK) pathways and insulin‐like signaling play pivotal roles in cellular stress response. Using an anti‐phospho‐SAPK/JNK antibody and a daf‐16::GFP‐based reporter assay, the present study shows in Caenorhabditis elegans that ambient temperature (1–37°C) specifically influences the activation (phosphorylation) of the MAP kinase JNK‐1 as well as the nuclear translocation of DAF‐16, the main downstream target of insulin‐like signaling. Activated JNK‐1 was detected only in neuronal cells, and JNK‐1 was found to be controlled by the MAPK JKK‐1 under heat stress. Comparative analyses on the wildtype and a jnk‐1 deletion mutant revealed a promoting influence of JNK‐1 on both nuclear DAF‐16 translocations and DAF‐16 target gene (superoxide dismutase 3, sod‐3) expressions within peripheral, non‐neuronal tissue. Consequently, the mutant exhibited a reduced thermal tolerance and reproductive fitness at higher temperatures. These results provide evidence of indirect interactions between neuronal MAPK and peripheral insulin‐like signaling in response to environmental stimuli (temperature, H2O2). J. Cell. Physiol. 214: 721–729, 2008. © 2007 Wiley‐Liss, Inc.
The Multi‐PDZ domain protein MUPP1 as a lipid raft‐associated scaffolding protein controlling the acrosome reaction in mammalian spermatozoa
Authors: Ackermann Frauke , Zitranski Nele , Heydecke Diana , Wilhelm Beate , Gudermann Thomas , Boekhoff Ingrid 
Published: September 2007

AbstractThe success of acrosomal exocytosis, a complex process with a variety of interrelated steps, relies on the coordinated interaction of participating signaling molecules. Since scaffolding proteins are known to spatially organize sequential signaling pathways, we examined whether the Multi‐PDZ domain protein MUPP1, recently identified in mammalian spermatozoa, is functionally active in controlling acrosomal secretion in mammalian sperm cells. To address this question, permeabilized mouse sperm were loaded with inhibitory antibodies against MUPP1 as well as with a photosensitive Ca2+ chelator which allows a controlled release of acrosomal Ca2+. The results revealed that MUPP1 controls initial tethering and docking of the acrosomal vesicle, whereas syntaxin 2, a t‐SNARE protein also expressed in the acrosomal cap of mammalian spermatozoa, appears to take part in the final process of acrosomal fusion. Interestingly, using immunogold electron microscopy, it was found that MUPP1 is detectable in the region of the periacrosomal membrane. Furthermore, in isolated detergent‐insoluble glycolipid‐enriched membrane domains from epididymal spermatozoa, MUPP1 was found to show a striking association with the Triton X‐100 insoluble membrane fraction, which did not change significantly upon sperm capacitation or partial chemical extraction of cholesterol. This evidence points to a role of MUPP1 as a membrane raft‐associated molecular organizer, and suggests that mammalian spermatozoa may use a scaffolding protein and distinct membrane subdomains to spatially organize components involved in the process of acrosomal exocytosis. J. Cell. Physiol. 214: 757–768, 2008. © 2007 Wiley‐Liss, Inc.
Gene expression fluctuations in murine hematopoietic stem cells with cell cycle progression
Authors: Dooner Gerri J. , Colvin Gerald A. , Dooner Mark S. , Johnson Kevin W. , Quesenberry Peter J. 
Published: September 2007

AbstractEvolving data suggest that marrow hematopoietic stem cells show reversible changes in homing, engraftment, and differentiation phenotype with cell cycle progression. Furthermore, marrow stem cells are a cycling population. Traditional concepts hold that the system is hierarchical, but the information on the lability of phenotype with cycle progression suggests a model in which stem cells are on a reversible continuum. Here we have investigated mRNA expression in murine lineage negative stem cell antigen‐1 positive stem cells of a variety of cell surface epitopes and transcription regulators associated with stem cell identity or regulation. At isolation these stem cells expressed almost all cell surface markers, and transcription factors studied, including receptors for G‐CSF, GM‐CSF, and IL‐7. When these stem cells were induced to transit cell cycle in vitro by exposure to interleukin‐3 (IL‐3), Il‐6, IL‐11, and steel factor some (CD34, CD45R c‐kit, Gata‐1, Gata‐2, Ikaros, and Fog) showed stable expression over time, despite previously documented alterations in phenotype, while others showed variation of expression between and within experiments. These latter included Sca‐1, Mac‐1, c‐fms, and c‐mpl. Tal‐1, endoglin, and CD4. These studies indicate that defined marrow stem cells express a wide variety of genes at isolation and with cytokine induced cell cycle transit show marked and reversible phenotype lability. Altogether, the phenotypic plasticity of gene expression for murine stem cells indicates a continuum model of stem cell regulation and extends the model to reversible expression with cell cycle transit of mRNA for cytokine receptors and stem cell markers. J. Cell. Physiol. 214: 786–795, 2008. © 2007 Wiley‐Liss, Inc.
DNA damage and cellular differentiation: More questions than responses
Authors: Simonatto Marta , Latella Lucia , Puri Pier Lorenzo 
Published: September 2007

AbstractStudies on DNA damage responses in proliferating cells have revealed the relationship between sensing and repair of the DNA lesions and the regulation of the cell cycle, leading to the discovery and molecular characterization of the DNA damage‐activated cell cycle checkpoints. Much less is known about the DNA damage response in progenitors of differentiated cells, in which cell cycle arrest is a critical signal to trigger the differentiation program, and in terminally differentiated cells, which are typically post‐mitotic. How DNA lesions are detected, processed and repaired in these cells, the functional impact of DNA damage on transcription of differentiation‐specific genes, how these events are coordinated at the molecular level, the consequence of defective DNA damage response on tissue‐specific functions and its potential relationship with age‐related diseases are currently open questions. In particular the biological complexity inherent to the global genome reprogramming of tissue progenitors, such as embryonic or adult stem cells, suggests the importance of an accurate DNA damage response at the transcription level in these cells to ensure the genomic integrity of regenerating tissues. J. Cell. Physiol. 213:642–648. © 2007 Wiley‐Liss, Inc.
Batch cultures of Penicillium camembertii on glucose and amino acids—model for growth and ammonium production
Authors: Ayati Fadila , Aziza Majda , Maachi Rachida , Amrane Abdeltif 
Published: September 2007

AbstractBACKGROUND: Three groups of amino acids were previously characterized based on their ability to be assimilated as carbon source by Penicillium camembertii. To describe the diauxic growth recorded on glucose and amino acids from the second group, such as arginine, an unstructured model was previously developed, based on the sequential consumption of both carbon substrates, glucose, followed after its exhaustion, by arginine. The model was modified to describe also the behaviour recorded during growth on other amino acids.RESULTS: The growth model involved the carbon substrate consumption (Verlhust model) and the biomass on carbon substrate yield. Glucose was therefore considered during P. camembertii growth on nitrogen source amino acids (lysine—first group); and amino acid consumption was considered during growth on carbon source amino acids (glutamate—third group), with glucose being dissimilated only for energy supply. The excess nitrogen from amino acids was released as ammonium; the linking of this production to growth was found to increase with the ability of the amino acid to be assimilated as carbon source by P. camembertii.CONCLUSION: The various metabolic behaviours recorded during P. camembertii growth on amino acids, in the presence of a primary carbon source such as glucose, were proved to be satisfactorily described by the model, showing the robustness of the model. Copyright © 2007 Society of Chemical Industry
Organoiridium complexes for hydrogen isotope exchange labeling
Authors: Heys J. Richard 
Published: September 2007

AbstractAn account of the development of organoiridium‐catalyzed hydrogen isotope exchange methods is given for the regioselective labeling of compounds from isotopic hydrogen gas, and their current status. The concept arose out of organometallic chemistry studies of C–H bond activation that revealed the ability of certain metal centers to interact with specific C–H bonds of molecules adjacent to coordinating heteroatoms. Initial success in labeling of model compounds with [Ir(H)2(acetone)2(PPh3)2]BF4 and deuterium gas provided the stimulus for further investigations into modified catalysts, their use with tritium, and applications to the labeling of a wide variety of more complex compounds. Over time, development of mechanistic models and accumulation of empirical data have grown sufficient to permit the prediction of applicability and regioselectivity based on compound structure. Continuing development of new organoiridium catalysts is broadening the range of compound types that can be labeled. Copyright © 2007 John Wiley & Sons, Ltd.
The history of the International Isotope Society
Authors: Susan Alexander B. 
Published: September 2007

AbstractThe author traces back to the late nineteen fifties the history of events preceding the current activities of the International Isotope Society (IIS) founded in 1986. The obvious conclusions are that there was a need for regular scientific meetings focused on topics such as the synthesis of isotopes, isotopically labelled and their applications. The various existing chemical and technical societies could not cover in their meetings such topics as efficiently as the IIS did. The Kansas City 1982 and 1985 first two unofficial meetings lead to the formation of the IIS in 1986 and then to a series of other regular symposia as 1988 (Innsbruck, Austria), 1991 (Toronto, Canada), 1994 (Strasbourg, France), 1997 (Philadelphia, USA), 2000 (Dresden, Germany), 2003 (Boston, USA), 2006 (Edinburgh, United Kingdom) and then in 2009 (Chicago, USA). The IIS also carries out its activities in yearly local Chapter meetings in the US, UK, Central Europe, Romania, Russia and China. At the same time, according to its Mission stated in the IIS Constitution (available in the www.intl.isotope‐soc.org website) the IIS also encourages the continuation of the independent meetings called the International Conferences of Isotopes; the activities of an international Low Level Waste IIS committee; the publication of the IIS Newsletter and maintenance of its website); organizing various workshops and short courses; and last but not least gives its support to the Journal of Labeled Compounds and Radiopharmaceutical by contributing papers and pro‐bono work on the Editorial as well as on the Advisory Board of the Journal. Copyright © 2007 John Wiley & Sons, Ltd.
[11C]Carbon monoxide, a versatile and useful precursor in labelling chemistry for PET‐ligand development
Authors: Långström Bengt , Itsenko Oleksiy , Rahman Obaidur 
Published: September 2007

AbstractIn this review the recent progress in the development of suitable precursors for 11C‐labelling is discussed. Especially the last few years' advancement of the use of [11C] carbon monoxide as a versatile and useful precursor in labelling chemistry is presented. The development is set in perspective of its potential in applying molecular imaging tools in drug and tracer development.The possibility of exploring small tracer libraries utilizing the microdosing concept is explored. Copyright © 2007 John Wiley & Sons, Ltd.
Neuro MR: Protocols
Authors: Mikulis David J. , Roberts Timothy P.L. 
Published: September 2007

AbstractClinical MRI depends on a symbiosis between MR physics and clinical requirements. The imaging solutions are based on a balance between the “palette” of available image contrasts derived from nuclear spin physics and tissue biophysics, and clinical determinants such as the anticipated pathology and efficient use of imaging time. Imaging is therefore optimized to maximize diagnostic sensitivity and specificity through the development of protocols organized along the lines of major disease categories. In the other part of this two‐part review, the primary determinants of image contrast, including T1, T2, and T2*, were highlighted. The development of pulse sequences designed to optimize each of these image contrasts was discussed and the impact of technological innovation (parallel imaging and high‐field systems) on the manner in which these sequences could be modified to improve clinical efficacy was further emphasized. The scope of that discussion was broadened to include the application of: 1) water diffusion imaging used primarily for detection of pathologies that restrict the free movement of water in the tissues and for defining fiber tracts in the brain; 2) the intravenous administration of exogenous contrast agents (gadolinium‐diethylene triamine pentaacetic acid [GdDTPA]) for assessment of blood‐brain‐barrier (BBB) defects and brain blood flow; and 3) MR spectroscopy (MRS) for assessment of brain metabolites. The goal of this part is to discuss how these acquisitions are combined into specific protocols that can effectively detect and characterize, or in keeping with our artistic analogy, “paint” each of the major diseases affecting the central nervous system (CNS). This work concludes with a discussion of image artifacts and pitfalls in image interpretation, which, in spite our best efforts to minimize or eliminate them, continue to occur. Much of the ensuing discussion is based on our own institutional experience. Protocols, therefore, do not necessarily match those from other institutions due to variability in clinical emphasis, MR instruments, and available software. An attempt was made to focus on basic clinical sequences that are available on most modern MR systems, with protocols employing generally accepted clinical imaging philosophies. J. Magn. Reson. Imaging 2007;26:838–847. © 2007 Wiley‐Liss, Inc.
Simultaneous myocardial and fat suppression in magnetic resonance myocardial delayed enhancement imaging
Authors: Foo Thomas K.F. , Slavin Glenn S. , Bluemke David A. , Montequin Marcela , Hood Maureen N. , Ho Vincent B. 
Published: September 2007

AbstractPurposeTo develop a method for fat suppression in myocardial delayed enhancement (MDE) studies that achieves effective signal intensity reduction in fat but does not perturb myocardial signal suppression.Materials and MethodsA new approach to fat suppression that uses a spectrally‐selective inversion‐recovery (SPEC‐IR) tip‐up radio frequency (RF) pulse following the conventional nonselective IR RF pulse together with a second SPEC‐IR RF pulse is proposed. The tip‐up pulse restores the fat longitudinal magnetization after the nonselective IR pulse and allows the fat magnetization to recover more fully toward its equilibrium value, providing for better fat suppression by the second SPEC‐IR RF pulse. This new approach was validated in phantom studies and in five patients.ResultsEffective fat suppression was achieved using the proposed technique with minimal impact on normal myocardial signal suppression. Mean fat suppression achieved using this approach was 67% ± 8%, as measured in the chest wall immediately opposite the heart.ConclusionThe results indicate this modular‐type approach optimizes fat suppression in myocardial delayed enhancement studies but does not perturb the basic IR pulse sequence or change basic acquisition parameters. J. Magn. Reson. Imaging 2007;26:927–933. © 2007 Wiley‐Liss, Inc.