bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aeolian activity at a giant sandstone weathering pit in arid south‐central Utah
Authors: Netoff Dennis I. , Chan Marjorie A. 
Published: August 2008

AbstractAeolian abrasional, depositional and deflational features indicate exceptionally strong southwesterly winds in a giant sandstone weathering pit in Grand Staircase Escalante Monument, about 22 km southeast of Escalante, Utah. The 60 m wide, 5–20 m deep pit has developed near the summit of a broad, barren 160‐m‐high dome on the Lower Jurassic Navajo Sandstone. Unlike other giant weathering pits (10–30 m diameter) in the region, the bedrock floor of this pit is undulatory, and there is a cylindrical, 10‐m‐high rock pedestal in the centre of the pit. An active dune surrounds the central pedestal and at times has as much as 8 m of local relief. The dune shifts considerably over brief (<1 year) periods of time. Fine‐grained (<250 µm) dunal sand on the pit floor is periodically removed by deflation, leaving coarser sand (>250 µm) trapped in the pit. Dunal sand is typically derived from external sources (other than the pit walls and floor). Centimetre to metre‐scale abrasional features such as grooves, flutes and dedos occur on the bedrock walls and floor of the pit. These dedos and other streamlined aeolian sculpted host‐rock features occur in clusters and typically form in the lee of iron concretions. The dedos are similar to the controversial stalked blueberries on Mars. Above the western rim of the pit there is a 29‐m‐long, 5‐m‐wide aeolian groove with a fluted bedrock floor. A 1·2‐km‐long bedrock valley descends to the southwest from the pit and groove, amplifying southwesterly winds. Data from hand‐held anemometers suggest that southwesterly winds can be accelerated 200–300 per cent or more by local topography. Copyright © 2008 John Wiley and Sons, Ltd.
Qualitative and quantitative applications of LiDAR imagery in fluvial geomorphology
Authors: Notebaert Bastiaan , Verstraeten Gert , Govers Gerard , Poesen Jean 
Published: August 2008

AbstractThe potential for geomorphological mapping and quantitative calculations of light detection and ranging (LiDAR) data within fluvial geomorphology was studied for two river catchments within Belgium (Dijle and Amblève), which differ in physical settings and floodplain morphology. Two commercial, of‐the‐shelf LiDAR datasets with different specifications (horizontal resolution and vertical accuracy) were available for parts of the floodplains of both catchments. Real‐time kinematic (RTK) Global Positioning System (GPS) data were used as ground truth for error calculations.Qualitative analysis of LiDAR data allowed the identification of former channel patterns, levees, colluvial hillslope and fan deposits. These results were confirmed by field data, topographic surveys and historical maps. The pixel resolution proved to be an important factor in the identification of small landforms: only features with a width equal to or larger than LiDAR resolution can be detected. This poses limits on the usability of regionally available LiDAR data, which often have a horizontal resolution of several metres.The LiDAR data were also used in a quantitative analysis of channel dynamics. In the study area, the width of the Dijle River channel increased 3 m on average between 1969 and 2003. A sediment budget of channel processes for the period 1969–2003 indicated a total river bank erosion of 16·1 103 m3 and a total within channel deposition of 7·1 103 m3, resulting in a net river erosion of 9·0 103 m3 or c. 0·4 Mg year−1 per metre river length. Sequential LiDAR data can in theory be used to calculate vertical sedimentation rates, as long as there is control on the error of the reference levels used. Copyright © 2008 John Wiley and Sons, Ltd.
The effect of shrub canopy upon surface temperatures and evaporation in the Negev Desert
Authors: Kidron Giora J. 
Published: August 2008

AbstractAlthough known as ‘islands of fertility’ or ‘resource islands’, information regarding the effect of shrubs upon microclimate in deserts is scarce. Here we report on measurements of evaporation and temperatures that were carried out in and around a pair of shrubs at the Nizzana research site in the western Negev Desert during 1993–94 and during the growing season (November–March) of 1994–95 and 1996–1997. Whereas evaporation was measured monthly using mini‐atmometers (10 cm diameter and 10 cm tall) at an exposed site and under and around the shrub (at the eastern, southern, western and northern aspects), temperature was measured under a shrub canopy, at its northern aspect, and at an exposed habitat. Evaporation was aspect dependent with increasing rates in the following order: exposed > south‐facing > west‐facing ≈ east‐facing > north‐facing > under canopy. Except from the northern aspect, the under‐canopy habitat showed substantially lower rates of evaporation in comparison with all other habitats. The differences between the under‐canopy and the exposed habitat were larger during wintertime (with the under‐canopy habitat having 0·53 times the evaporation rate than that of the exposed habitat) although higher differences in temperatures characterized both habitats in summertime (up to 14·4 °C in summer as compared with 6·9 °C only in winter). The results were explained by extended surface wetness that characterized the under‐canopy habitat following rainstorms. While already being dried out at the exposed habitat, surface wetness at the under canopy habitat persisted for several days afterwards, resulting, following one rainstorm, in vapour pressure of 2·15–2·39 kPa in comparison with only 0·82–0·83 kPa of the exposed habitat. The substantially lower evaporation rates that characterize the under‐canopy habitat may thus play a pivotal role in providing preferential conditions for lush under‐canopy annual growth. Copyright © 2008 John Wiley and Sons, Ltd.
Flow energy and channel adjustments in rills developed in loamy sand and sandy loam soils
Authors: Stefanovic Jovan R. , Bryan Rorke B. 
Published: August 2008

AbstractThe storms usually associated with rill development in nature are seldom prolonged, so development is often interrupted by interstorm disturbances, e.g. weathering or tillage. In laboratory simulated rainfall experiments, active rill development can be prolonged, and under these conditions typically passes through a period of intense incision, channel extension and bifurcation before reaching quasi‐stable conditions in which little form change occurs. This paper presents laboratory experiments with coarse textured soils under simulated rainfall which show how channel adjustment processes contribute to the evolution of quasi‐stability.Newly incised rills were stabilized for detailed study of links between rill configuration and flow energy. On a loamy sand, adjustment towards equilibrium occurred due to channel widening and meandering, whereas on a sandy loam, mobile knickpoints and chutes, pulsations in flow width and flow depth and changes in stream power and sediment discharge occurred as the channel adjusted towards equilibrium. The tendency of rill systems towards quasi‐stability is shown by changes in stream power values which show short‐lived minima. Differences in energy dissipation in stabilized rills indicate that minimization of energy dissipation was reached locally between knickpoints and at the downstream ends of rills. In the absence of energy gradients in knickpoints and chutes, stabilized rill sections tended toward equilibrium by establishing uniform energy expenditure. The study confirmed that energy dissipation increased with flow aspect ratio. In stabilized rills, flow acceleration reduced energy dissipation on the loamy sand but not on the sandy loam. On both soils flow deceleration tended to increase energy dissipation.Understanding how rill systems evolve towards stability is essential in order to predict how interruptions between storms may affect long‐term rill dynamics. This is essential if event‐based physical models are to become effective in predicting sediment transport on rilled hillslopes under changing weather and climatic conditions. Copyright © 2008 John Wiley and Sons, Ltd.
Nonalcoholic steatohepatitis is associated with altered hepatic MicroRNA expression
Authors: Cheung Onpan , Puri Puneet , Eicken Christoph , Contos Melissa J. , Mirshahi Faridoddin , Maher James W. , Kellum John M. , Min Haeki , Luketic Velimir A. , Sanyal Arun J. 
Published: August 2008

Abstract

The expression of microRNA in nonalcoholic steatohepatitis (NASH) and their role in the genesis of NASH are not known. The aims of this study were to: (1) identify differentially expressed microRNAs in human NASH, (2) tabulate their potential targets, and (3) define the effect of a specific differentially expressed microRNA, miR-122, on its targets and compare these effects with the pattern of expression of these targets in human NASH. The expression of 474 human microRNAs was compared in subjects with the metabolic syndrome and NASH versus controls with normal liver histology. Differentially expressed microRNAs were identified by the μParaflo microRNA microarray assay and validated using quantitative real-time polymerase chain reaction (PCR). The effects of a specific differentially expressed miRNA (miR-122) on its predicted targets were assessed by silencing and overexpressing miR-122

in vitro

. A total of 23 microRNAs were underexpressed or overexpressed. The predicted targets of these microRNAs are known to affect cell proliferation, protein translation, apoptosis, inflammation, oxidative stress, and metabolism. The miR-122 level was significantly decreased in subjects with NASH (63% by real-time PCR,

P

< 0.00001). Silencing miR-122 led to an initial increase in mRNA levels of these targets (

P

< 0.05 for all) followed by a decrease by 48 hours. This was accompanied by an increase in protein levels of these targets (

P

< 0.05 for all). Overexpression of miR-122 led to a significant decrease in protein levels of these targets.

Conclusions

: NASH is associated with altered hepatic microRNA expression. Underexpression of miR-122 potentially contributes to altered lipid metabolism implicated in the pathogenesis of NASH. (Hepatology 2008;48:1810–1820.)
Circadian rhythm disturbances in depression
Authors: Germain Anne , Kupfer David J. 
Published: August 2008

AbstractObjectiveThe aim of this article is to review progress in understanding the mechanisms that underlie circadian and sleep rhythms, and their role in the pathogenesis and treatment of depression.MethodsLiterature was selected principally by Medline searches, and additional reports were identified based on ongoing research activities in the authors' laboratory.ResultsMany physiological processes show circadian rhythms of activity. Sleep and waking are the most obvious circadian rhythms in mammals. There is considerable evidence that circadian and sleep disturbances are important in the pathophysiology of mood disorders. Depressed patients often show altered circadian rhythms, sleep disturbances, and diurnal mood variation. Chronotherapies, including bright light exposure, sleep deprivation, and social rhythm therapies, may be useful adjuncts in non‐seasonal and seasonal depression. Antidepressant drugs have marked effects on circadian processes and sleep.ConclusionsRecent progress in understanding chronobiological and sleep regulation mechanisms may provide novel insights and avenues into the development of new pharmacological and behavioral treatment strategies for mood disorders. Copyright © 2008 John Wiley & Sons, Ltd.
Bone grafts cultured with bone marrow stromal cells for the repair of critical bone defects: An experimental study in mice
Authors: Dumas Aline , Moreau Marie‐Françoise , Ghérardi Romain K. , Baslé Michel F. , Chappard Daniel 
Published: August 2008

AbstractTissue engineering of autologous bone combined with osteoprogenitor cells is a suitable strategy for filling large bone defects. The aim of this study was to evaluate the osteogenicity of a xenogenic bone graft cultured with allogenic bone marrow stromal cells (BMSC) in a mouse critical size craniotomy. Bovine trabecular bone grafts were made free of bone marrow cells or debris and were delipidated. BMSC were harvested from C57BL/6‐Tg(ACTbEGFP)1Osb/J mice (GFP+ cells) and were cultured 14 days on bone grafts in control or osteogenic medium. Engineered grafts were implanted in calvarial defect in C57BL/6 mice. Four groups were studied: graft with BMSC differentiated in osteoblasts (G‐Ob), graft with BMSC (G‐BMSC), graft without cells (G) and no graft. Calvariae were studied 2 and 8 weeks after implantation by radiographic and histomorphometric analyses. G group: the bone ingrowth was limited to the edges of the defect. The center of the graft was filled by a fibrovascular connective tissue. G‐BMSC or G‐Ob groups: bone formation occurred early in the center of the defect and did not increase between 2 and 8 weeks; the newly formed woven bone was partially replaced by lamellar bone. The preoperative osteoblastic differentiation of BMSC did not allow faster and better bone regeneration. After 2 weeks, GFP+ cells were observed around the grafted bone but no GFP+ osteocyte was present in the newly formed bone. No GFP+ cell was noted after 8 weeks. However, pre‐implantation culture of the biomaterial with allogenic BMSC greatly enhanced the bone regeneration. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
A versatile mesoindentation system to evaluate the micromechanical properties of soft, hydrated substrates on a cellular scale
Authors: Saxena Tarun , Gilbert Jeremy L. , Hasenwinkel Julie M. 
Published: August 2008

AbstractIt has become increasingly important to study mechanical properties of substrates on the cellular scale since cells sense and respond to changes in the microenvironment in which they are grown. To study the effects of mechanical substrate properties on the cellular scale, an existing microindentation system has been modified to perform indentation tests on highly hydrated polymeric substrates and tissues. The highly sensitive, modified indentation system, labeled as a mesoindenter, is versatile and can be customized to perform a variety of tests useful for studying tissue mechanics, stress relaxation in polymers, and interfacial adhesion phenomena. To validate the efficacy and accuracy of the system, soft, hydrated hydrogels made from agarose (1–5 wt %), poly(2‐hydroxyethyl methacrylate) (p(HEMA)) (60–90% water), and unfixed, saline‐perfused rat spinal cord tissue were tested. The results demonstrate that moduli vary with water content and are in line with previously published studies. We also demonstrate that the modulus of hydrogels is sensitive to the preload applied, with modulus increasing with preload. Stress relaxation indentation testing of p(HEMA) showed relaxation behavior that can be modeled using a heredity integral and standard linear model. The mesoindenter is versatile, capable of scanning and testing immersed samples, and easily customized to ascertain mechanical properties of substrates ranging from the kPa to GPa range. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Titanium IV ions induced human osteoclast differentiation and enhanced bone resorption in vitro
Authors: Cadosch Dieter , Chan Erwin , Gautschi Oliver P. , Meagher James , Zellweger René , Filgueira Luis 
Published: August 2008

AbstractThere is increasing evidence that titanium (Ti) ions are released from orthopedic implants, with concentrations in the range of 1 μM in tissue and blood, and may play a role in aseptic loosening of orthopedic implants. This study investigated whether Ti(IV) ions induce differentiation of monocytic osteoclast precursors into osteo‐resorptive multinucleated cells and influence the activation and function of in vitro generated osteoclasts. Human monocytes and in vitro generated osteoclasts were exposed to 1 μM Ti(IV) ions for 10 days. Thereafter, osteoclast differentiation, activation, and function were evaluated. Transcription of specific osteoclastic genes was measured using quantitative reverse transcription polymerase chain reactions, which showed increased expression of tartrate‐resistant acid phosphatase (TRAP) in ∼20% of Ti(IV)‐treated monocytes. Detection and quantification of intracellular TRAP activity using ELF97 as a fluorescent substrate revealed a significant increase of TRAP‐positive cells in Ti(IV)‐treated monocytes. Additionally, as demonstrated on dentin slide cultures, Ti(IV)‐treated monocytes became functional bone resorbing cells, significantly increasing their osteo‐resorptive activity to similar levels as osteoclasts in vitro. These results suggest that Ti(IV) ions released by biocorrosion from orthopedic implants induce differentiation of monocytes toward mature, functional osteoclasts, which may well contribute the pathomechanism of aseptic loosening. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Influence of pretreatment on the surface characteristics of PLLA fibers and subsequent hydroxyapatite coating
Authors: Peng F. , Olson J.R. , Shaw M.T. , Wei M. 
Published: August 2008

AbstractA fibrous precursor for bone repair composites was made by coating poly(L‐lactide) (PLLA) fibers with hydroxyapatite (HA) using a biomimetic method. To enhance the bonding between the HA coating and the PLLA fiber, PLLA fibers were etched with either sodium hydroxide or sodium hypochlorite to generate carboxyl groups on fiber surfaces. The experiments were designed to determine the influence of etching on the fiber surface morphology and chemistry as well as the subsequent HA coating on the etched fiber surfaces. It was found that the etching pretreatment increased the roughness as well as the hydrophilicity of fibers, indicating that hydrolysis of PLLA chains had taken place on fiber surfaces. The etching pretreatment also promoted HA coating formation by introducing thicker coating on the surface of fibers with a longer etching time, a higher etching concentration, or with NaOCl as the etching agent. A mechanism of surface hydrolysis and oxidation of PLLA was proposed. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Intruder states in multireference perturbation theory: The ground state of manganese dimer
Authors: Camacho Cristopher , Witek Henryk A. , Yamamoto Shigeyoshi 
Published: August 2008

AbstractA detailed analysis of a severe intruder state problem in the multistate multireference perturbation theory (MS‐MRPT) calculations on the ground state of manganese dimer is presented. An enormous number of detected intruder states (> 5000) do not permit finding even an approximate shape of the X1Σ potential energy curve. The intruder states are explicitly demonstrated to originate from quasidegeneracies in the zeroth‐order Hamiltonian spectrum. The electronic configurations responsible for appearance of the quasidegeneracies are identified as single and double excitations from the active orbitals to the external orbitals. It is shown that the quasidegeneracy problem can be completely eliminated using shift techniques despite of its severity. The resultant curves are smooth and continuous. Unfortunately, strong dependence of the spectroscopic parameters of the X1Σ state on the shift parameter is observed. This finding rises serious controversies regarding validity of employing shift techniques for solving the intruder state problem in MS‐MRPT. Various alternative approaches of removing intruder states (e.g., modification of the basis set or changing the active space) are tested. None of these conventional techniques is able to fully avoid the quasidegeneracies. We believe that the MS‐MRPT calculations on the three lowest Ag states of manganese dimer constitute a perfect benchmark case for studying the behavior of MRPT in extreme situations. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Estimation and extraction of B‐cell linear epitopes predicted by mathematical morphology approaches
Authors: Chang Hao‐Teng , Liu Chih‐Hong , Pai Tun‐Wen 
Published: August 2008

AbstractB‐cell epitope prediction facilitates the design and synthesis of short peptides for various immunological applications. Several algorithms have been developed to predict B‐cell linear epitopes (LEs) from primary sequences of antigens, providing important information for immunobiological experiments and antibody design. This paper describes two robust methods, LE prediction with/without local peak extraction (LEP‐LP and LEP‐NLP), based on antigenicity scale and mathematical morphology for the prediction of B‐cell LEs. Previous studies revealed that LEs could occur in regions with low‐to‐moderate but not globally high antigenicity scales. Hence, we developed a method adopting mathematical morphology to extract local peaks from a linear combination of the propensity scales of physico‐chemical characteristics at each antigen residue. Comparison among LEP‐LP/LEP‐NLP, BepiPred and BEPITOPE revealed that our algorithms performed better in retrieving epitopes with low‐to‐moderate antigenicity and achieved comparable performance according to receiver operation characteristics (ROC) curve analysis. Of the identified LEs, over 30% were unable to be predicted by BepiPred and BEPITOPE employing an average threshold of antigenicity index or default settings. Our LEP‐LP method provides a bioinformatics approach for predicting B‐cell LEs with low‐ to‐moderate antigenicity. The web‐based server was established at http://biotools.cs.ntou.edu.tw/lepd_antigenicity. php for free use. Copyright © 2008 John Wiley & Sons, Ltd.
Excitatory effects of low‐level lead exposure on action potential firing of pyramidal neurons in CA1 region of rat hippocampal slices
Authors: Yan Dan , Xiao Cheng , Ma Fang‐li , Wang Lang , Luo Yun‐Yun , Liu Jin , Wang Hui‐Li , Chen Ju‐Tao , Ruan Di‐Yun 
Published: August 2008

AbstractLead is putatively regarded as an environmental neurotoxicant. Long‐term low‐level lead exposure causes cognitive deficits, but the mechanism remains to be elucidated. In the present study, the excitatory effects of low‐level lead exposure on action potential (AP) firing of pyramidal neurons in CA1 region of rat hippocampal slices and the pathway through which lead induced these effects were studied with conventional whole‐cell recording. Low‐level lead (0.5 and 5 μM) exposure did not significantly change either voltage threshold or amplitude, duration, rise time, or rising velocity of single AP; conversely, 5 μM lead exposure significantly increased AP firing rates and reduced spike frequency adaptation. These excitatory effects of 5 μM lead were blocked by mibefradil, a selective blocker of T‐type voltage‐dependent calcium channels (VDCC), but not by verapamil and ω‐conotoxin, selective blockers of L‐ type and N‐type VDCC, respectively. Five micromolar lead could not change the excitability of pyramidal neurons when slices were perfused with calcium‐free ACSF. In addition, the effects were abolished by inhibitors of two intracellular calcium release channels: 2‐APB, an inhibitor of inositol trisphosphate receptors, and dantrolene, an inhibitor of ryanodine receptors, but not by thapsigargin, an inhibitor of endoplasmic reticulum calcium uptake. These results provide evidence for excitatory neurotoxicity of low‐level lead exposure, contribution of T‐type VDCC in the entrance of lead into neurons, and a possible involvement of calcium flux alteration during APs in this excitatory neurotoxicity. © 2008 Wiley‐Liss, Inc.