bluuebunny/crossref_metadata_2025_split huggingface dataset:
Boundary and border considerations in hydrology
Authors: Woo Ming‐ko 
Published: March 2004

AbstractThis paper examines several issues related to hydrological boundaries and their border zones. In a two‐dimensional space, a boundary is a line that separates two domains possessing different hydrological properties or dominated by different hydrological processes, and a border is an area that experiences an edge effect owing to transitions or mixing of processes. Hydrological boundaries may be static, such as drainage divides, or dynamic, such as the edges of a seasonal snow cover. They may be open or closed to the transfer of matter and energy, although most boundaries tend to be perforated, permitting different rates of movement across different segments. Borders may be narrow or the edge effect can affect large areas, as happens to the sensible heat flux over a highly fragmented melting snowfield. The introduction of artificial boundaries, notably the grid patterns of remote sensing pixels, digital elevation models and land surface schemes, gives rise to problems of mismatch with the natural hydrological boundaries. Incorrect demarcation, omission and generalization of boundaries can produce errors that are hard to rectify. Serious biases are involved when point observations are used to calibrate parameters or to validate model outputs integrated over a bounded area. Examples are drawn mainly from cold climate hydrology to illustrate the boundary issues but the questions transcend disciplinary areas. The intent of this presentation is to stimulate discussions that could be a prelude to finding solutions to many boundary problems which have thus far eluded hydrological investigations. Copyright © 2004 John Wiley & Sons, Ltd.
A simulation of large‐scale groundwater flow and travel time in a fractured rock environment for waste disposal purposes
Authors: Ophori Duke U. 
Published: March 2004

AbstractTwo‐dimensional regional groundwater flow was simulated based on a conceptual model of low‐permeability crystalline rocks of the Whiteshell Research Area (WRA) in south‐eastern Manitoba. The conceptual model consists of fracture zones that strike in different directions and dip at various angles in the background rock mass. The thickness and hydraulic properties of the fracture zones in the conceptual model were varied as were the fluid properties and the boundary conditions of the groundwater flow system. The effects of these variations on the groundwater flow pattern and on the convective travel time along pathways from a hypothetical disposal vault at 500 m depth to discharge locations at the ground surface were evaluated. The vault was located in the regional discharge area of the groundwater system. A homogeneous conceptual model of the WRA, having only freshwater flow, formed a groundwater flow pattern with a regional flow system. Local flow systems developed increasingly with the introduction of fracture zones 20 m and 3 m thick, and depth‐dependent fluid density. This indicates a reduction in groundwater residence time by fracture zones and fluid density. Flow pathways were analysed using both a stream‐function and a particle‐tracking technique. The pathways and their lengths from the location of the vault to the surface varied spatially according to the flow patterns. The minimum travel time along these pathways was less than 150 000 and greater than 4 000 000 years in models with and without fracture zones, respectively, indicating that the presence of fracture zones was the major controlling factor. A precise knowledge and refinement of conceptual model parameters is necessary during site selection for waste disposal purposes. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling the effects of land‐use change on water and salt delivery from a catchment affected by dryland salinity in south‐east Australia
Authors: Vaze Jai , Barnett Paul , Beale Geoffrey , Dawes Warrick , Evans Ray , Tuteja Narendra Kumar , Murphy Brian , Geeves Guy , Miller Michelle 
Published: March 2004

AbstractA comprehensive framework for the assessment of water and salt balance for large catchments affected by dryland salinity is applied to the Boorowa River catchment (1550 km2), located in south‐eastern Australia. The framework comprised two models, each focusing on a different aspect and operating on a different scale. A quasi‐physical semi‐distributed model CATSALT was used to estimate runoff and salt fluxes from different source areas within the catchment. The effects of land use, climate, topography, soils and geology are included. A groundwater model FLOWTUBE was used to estimate the long‐term effects of land‐use change on groundwater discharge. Unlike conventional salinity studies that focus on groundwater alone, this study makes use of a new approach to explore surface and groundwater interactions with salt stores and the stream.Land‐use change scenarios based on increased perennial pasture and tree‐cover content of the vegetation, aimed at high leakage and saline discharge areas, are investigated. Likely downstream impacts of the reduction in flow and salt export are estimated.The water balance model was able to simulate both the daily observed stream flow and salt load at the catchment outlet for high and low flow conditions satisfactorily. Mean leakage rate of about 23·2 mm year−1 under current land use for the Boorowa catchment was estimated. The corresponding mean runoff and salt export from the catchment were 89 382 ML year−1 and 38 938 t year−1, respectively.Investigation of various land‐use change scenarios indicates that changing annual pastures and cropping areas to perennial pastures is not likely to result in substantial improvement of water quality in the Boorowa River. A land‐use change of about 20% tree‐cover, specifically targeting high recharge and the saline discharge areas, would be needed to decrease stream salinity by 150 µS cm−1 from its current level. Stream salinity reductions of about 20 µS cm−1 in the main Lachlan River downstream of the confluence of the Boorowa River is predicted.The FLOWTUBE modelling within the Boorowa River catchment indicated that discharge areas under increased recharge conditions could re‐equilibrate in around 20 years for the catchment, and around 15 years for individual hillslopes. Copyright © 2004 John Wiley & Sons, Ltd.
A fast method of flood discharge estimation
Authors: Chen Yen‐Chang , Chiu Chao‐Lin 
Published: March 2004

AbstractDischarge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open‐channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross‐section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross‐sectional area can be determined from the gauge height, the water depth at the y‐axis or the product of the channel width multiplied by the water depth at the y‐axis. Then the most commonly used method, i.e. the velocity–area method, which determines discharge as the product of the cross‐sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y‐axis are necessary to estimate flood discharge. Moreover the location of the y‐axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream‐flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. Copyright © 2004 John Wiley & Sons, Ltd.
Ser‐249TP53 mutation in tumour and plasma DNA of hepatocellular carcinoma patients from a high incidence area in the Gambia, West Africa
Authors: Szymańska Katarzyna , Lesi Olufunmilayo A. , Kirk Gregory D. , Sam Omar , Taniere Philippe , Scoazec Jean‐Yves , Mendy Maimuna , Friesen Marlin D. , Whittle Hilton , Montesano Ruggero , Hainaut Pierre 
Published: March 2004

AbstractHepatocellular carcinoma (HCC) is frequent in areas of high exposure to aflatoxin and high prevalence of HBV infection, such as western Africa and south‐east China. A selective mutation in TP53 (AGG→AGT at codon 249, Arg→Ser) has been identified as a hotspot in HCCs from such areas, reflecting DNA damage caused by aflatoxin metabolites. Recent studies have shown that circulating free DNA can be retrieved from human plasma, and it is hypothesised that plasma DNA may serve as a source for biomarkers of tumorigenic processes. In our study, we have determined the prevalence of Ser‐249 mutation, using a PCR‐restriction digestion method, with selective use of short oligonucleotide mass spectrometry analysis (SOMA), in a series of 29 biopsy specimens of HCC from The Gambia in West Africa. Overall, we identified the Ser‐249 mutation in 35% (10/29) of the tumours. In parallel, we tested 17 plasma samples from HCC patients with matching tumour tissue. The 249 status concordance between tumour tissues and matched plasma was 88.5%. These results indicate that the Ser‐249 mutation is common in HCC in The Gambia (35%), although a higher prevalence has been reported in other regions with high population exposure to aflatoxin (e.g., eastern China: >50%). Moreover, our studies indicate that plasma is a convenient source of liver tumour‐derived DNA, thus holding promise for earlier detection and diagnosis of cancer. © 2004 Wiley‐Liss, Inc.
Expression of the metastasis‐associated MTA1 protein and its relationship to deacetylation of the histone H4 in esophageal squamous cell carcinomas
Authors: Toh Yasushi , Ohga Takefumi , Endo Kazuya , Adachi Eisuke , Kusumoto Hiroki , Haraguchi Masaru , Okamura Takeshi , Nicolson Garth L. 
Published: March 2004

AbstractMetastasis‐associated protein MTA1 and histone deacetylase form a protein complex with histone deacetylase activity that plays an important role in histone deacetylation, alteration of chromatin structure and transcriptional control. The precise role of the MTA1 protein in the malignant progression of human cancers remains unknown, however, especially its overexpression and relationship with histone acetylation/deacetylation in experimental and clinical tumors. The expression levels of MTA1 protein and the acetylation levels of histone H4 were examined in 70 cases of surgically resected esophageal squamous cell carcinomas, using immunohistochemistry. The intensities of immunostaining of MTA1 protein and acetylated histone H4 in carcinoma tissues (Ca) were compared to normal epithelium (N) contained in the same section. Thirty of 70 cases (42.9%) displayed overexpression of MTA1 protein (N < Ca). Cancers overexpressing MTA1 protein invaded deeper into the esophageal wall (p < 0.005) and showed significantly higher degrees of lymph node metastasis (p < 0.01), higher pathological stage, more lymphatic involvement and poorer prognosis (p < 0.05) than the remaining cases. The acetylation levels of histone H4 inversely correlated to the depth of cancer invasion and pathological stage (p < 0.05), and the patients with higher level of histone H4 acetylation had a better prognosis (p < 0.05). Furthermore, immunostaining patterns of MTA1 and acetylated histone H4 were inversely correlated (p < 0.001), demonstrating the relationship of deacetylation of histone H4 in MTA1‐overexpressing carcinomas. In conclusion, the data suggest that the overexpression of MTA1 protein and acetylation level of histone H4 protein, both of which are closely related, might be useful predictors of malignant potential of esophageal squamous cell carcinomas. Thus, strategies involving inhibition of MTA1 function as well as inhibition of histone deacetylation could be novel approaches for the treatment of esophageal squamous cell carcinomas. © 2004 Wiley‐Liss, Inc.
Succimer treatment and calcium supplementation reduce tissue lead in suckling rats
Authors: Marija Varnai Veda , Piasek Martina , Blanuša Maja , Matek Sarić Marijana , Jureša Dijana , Kostial Krista 
Published: March 2004

AbstractThe effect of combined treatment with meso‐2,3‐dimercaptosuccinic acid (DMSA) and calcium supplementation in reducing lead absorption and enhancing lead elimination was evaluated in suckling rats under two experimental conditions: during ongoing oral lead exposure (lead acetate, 2 mg Pb kg−1 day−1, total dose 16 mg Pb kg−1) or after lead exposure (72 h after a 2‐day lead exposure, total dose 12 mg Pb kg−1 s.c.). The artificial feeding method was used for calcium supplementation, with 6% Ca (as CaHPO4) suspension in cow's milk to increase the daily calcium intake about three times above control values. Artificial feeding lasted for 7 h a day over eight consecutive days. During this period DMSA was administered on 6 days twice a day (0.5 mmol kg−1 day−1 p.o.). At the end of the experiments, Pb, Ca and Zn in the carcass and Pb, Fe and Cu in the liver, kidneys and brain were analysed by atomic absorption spectrometry.Calcium supplementation during lead exposure reduced tissue lead but had no effect when applied after lead exposure, and DMSA administered either during or after lead exposure lowered the tissue lead. Combined treatment during ongoing lead exposure caused a greater reduction in tissue lead than either DMSA or calcium treatment alone. When administered after lead exposure, it had no advantage over DMSA treatment alone but did not impair its efficacy. Combined treatment had no influence on growth and did not seriously disturb essential element status. It is concluded that calcium supplementation could be applied during DMSA therapy, when indicated. Copyright © 2004 John Wiley & Sons, Ltd.
Tissue regeneration patterns in acellular bovine pericardia implanted in a canine model as a vascular patch
Authors: Chang Yen , Liang Huang‐Chien , Wei Hao‐Ji , Chu Chih‐Ping , Sung Hsing‐Wen 
Published: March 2004

AbstractIt was noted in our previous study that acellular tissues can provide a natural microenvironment for host cell migration and proliferation to accelerate tissue regeneration. The purpose of this study was to further investigate the tissue regeneration patterns in acellular bovine pericardia fixed with glutaraldehyde or genipin as a biological patch to repair a defect in the pulmonary trunk in a canine model. The implanted samples were retrieved at distinct durations postoperatively. The structural remodeling of retrieved samples was then examined. It was found that the degree of inflammatory reaction observed for the genipin‐fixed acellular patch was significantly less than its glutaraldehyde‐fixed counterpart. At 1 month postoperatively, intimal thickening was found on the inner surfaces of both studied groups. The intimal thickening observed on the glutaraldehyde‐fixed acellular patch was significantly thicker than its genipin‐fixed counterpart. An intact layer of endothelial cells was found on the intimal thickening of the genipin‐fixed acellular patch, whereas endothelial cells did not universally and totally cover the entire surface of the glutaraldehyde‐fixed acellular patch. Additionally, fibroblasts with neocollagen fibrils and myofibroblasts were observed in the acellular patches for both studied groups, an indication of tissue regeneration. This phenomenon was more prominent for the genipin‐fixed acellular patch than its glutaraldehyde‐fixed counterpart. At 6 months postoperatively, foci of chondroid and/or bony metaplasia were found in each retrieved sample for both studied groups. The observed adverse response of chondroid metaplasia may be attributed to a compliance mismatch at the implanted site of the canine pulmonary trunk after implantation or a lack of angiogenesis in the regenerated tissue observed at 1 month postoperatively. Bony metaplasia may then develop as in other chondroid tissues. It was reported that ischemia is a usual cause of metaplasia. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 323–333, 2004
Hierarchically biomimetic bone scaffold materials: Nano‐HA/collagen/PLA composite
Authors: Liao S. S. , Cui F. Z. , Zhang W. , Feng Q. L. 
Published: March 2004

AbstractA bone scaffold material (nano‐HA/ collagen/PLA composite) was developed by biomimetic synthesis. It shows some features of natural bone both in main composition and hierarchical microstructure. Nano‐hydroxyapatite and collagen assembled into mineralized fibril. The three‐dimensional porous scaffold materials mimic the microstructure of cancellous bone. Cell culture and animal model tests showed that the composite material is bioactive. The osteoblasts were separated from the neonatal rat calvaria. Osteoblasts adhered, spread, and proliferated throughout the pores of the scaffold material within a week. A 15‐mm segmental defect model in the radius of the rabbit was used to evaluate the bone‐remodeling ability of the composite. Combined with 0.5 mg rhBMP‐2, the material block was implanted into the defect. The segmental defect was integrated 12 weeks after surgery, and the implanted composite was partially substituted by new bone tissue. This scaffold composite has promise for the clinical repair of large bony defects according to the principles of bone tissue engineering. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 158–165, 2004
The effect of cesium‐containing leucite additions on the thermal and mechanical properties of two leucite‐based porcelains
Authors: Rasmussen Stephen T. , McLaren Charles I. , O'Brien William J. 
Published: March 2004

AbstractIt has been demonstrated that a Cs2O‐stabilized leucite porcelain was susceptible to a stress‐induced phase transformation, but toughening was not observed.1 It was hypothesized that if Cs2O‐stabilized leucite core particles were added to a cesium‐free matrix porcelain, selected or designed to enhance the toughening mechanism, toughening would occur. A commercial porcelain (VP) and a synthesized leucite‐based porcelain (NP) were the matrix materials. Core particles of Cs2O (0.0–2.0 mol%) containing synthetic leucite were mixed with the two cesium‐free matrix porcelains and vacuum fired into specimens for testing. The toughness of both types of matrix‐based materials was dependent upon cesium content of the added core particles with a maximum toughness reached for those containing 0.75 mol% Cs2O. The toughness of the 0.75 mol% specimens (1.42 MNm−3/2 for VP based and 2.15 MNm−3/2 for NP based) was statistically (p < .02) higher than either of the matrix materials alone or the matrix materials containing added core particles of synthetic cesium‐free leucite. However, the toughest materials (0.75 mol% Cs2O) were not the strongest materials, most likely because of large internal flaws. The results suggested that transformation toughening was possible. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 195–204, 2004
A new resin matrix for dental composite having low volumetric shrinkage
Authors: Kim Y. , Kim C. K. , Cho B. H. , Son H. H. , Um C. M. , Kim O. Y. 
Published: March 2004

AbstractThe applications of dental restorative composite resins containing 2,2 bis [4‐(2‐hydroxy‐3‐methacryloyloxy propoxy) phenyl] propane (Bis‐GMA), as a base resin, and triethylene glycol dimethacrylate (TEGDMA), as a diluent, are often limited in dentistry due to the relatively large amount of volumetric shrinkage that occurs during the curing reaction. In this study, various new resin matrices were examined for use as dental composites in order to reduce the amount of volumetric shrinkage that occurs in dental composites as a result of curing. Bis‐GMA derivatives were synthesized by substituting methyl groups for hydrogen on the phenyl ring. The derivatives of TEGDMA with different chain lengths or reactive groups were also examined. The molecular structural changes in the TEGDMA derivatives were not effective in reducing the level of volumetric shrinkage. The resin matrix containing a Bis‐GMA derivative and TEGDMA showed a reduced amount of volumetric shrinkage in proportion to the number of methyl groups on the phenyl rings. Polymerization with a mixture of Bis‐GMA, its derivatives and a diluent is a promising strategy for obtaining a polymer with a low amount of volumetric shrinkage. A comparison of the volumetric shrinkage of dental composites containing Bis‐GMA, TMBis‐GMA (2,2‐bis[3,5‐dimethyl, 4‐(2‐hydroxy‐3‐methacryloyloxy propoxy) phenyl] propane)), and TEGDMA with that prepared from a Bis‐GMA and TEGDMA mixture showed that the volumetric shrinkage reduction in the new resin was approximately 50%. Furthermore, the mechanical strength of the former was higher than that of the latter. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 82–90, 2004
Quantitative analysis of biologic specimens by X‐ray scanning analytic microscopy
Authors: Uo Motohiro , Tanaka Masaya , Watari Fumio 
Published: March 2004

AbstractX‐ray scanning analytic microscopy (XSAM) can be used to visualize the elemental distribution in biologic specimens. In this article, the authors prepared standard specimens for XSAM and performed quantitative analysis of various elements dissolved in soft tissues. Two different types of standard specimens were prepared. Methylmethacrylate (MMA) resin‐based standard specimens were prepared with organic compounds of elements for low‐concentration standards and lithium borate glass‐based standard specimens were prepared with oxides of elements for higher concentration standards. Using these standard specimens, the P and Ca concentrations in normal rat tissue and dissolved Ni, Fe, and Ni concentrations around metal‐implanted tissues were quantitatively analyzed. The estimated concentrations of dissolved Fe, Cu, and Ni from the implants were 1000, 40, and 20 mM, respectively. From the concentration levels causing inflammation around these implants, the high toxicity for soft tissue of Ni and Cu at low concentrations, for example, 10 mM, was confirmed. The toxicity of Cu was estimated as next to that of Ni. In contrast, Fe had low toxicity despite high concentrations of dissolved Fe of as much as 1000 mM. In this article, it was possible to estimate the nonmetallic elements and low‐concentration metallic elements dispersed in soft tissue by XSAM. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 146–151, 2004