bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the effects of ultrafine particulate matter while accounting for human exposure
Authors: REICH B. J. , Fuentes Montserrat , Burke Janet 
Published: April 2008

AbstractParticulate matter (PM) has been associated with mortality in several epidemiological studies. The US EPA currently regulates PM10 and PM2.5 (mass concentration of particles with diameter less than 10 and 2.5 µm, respectively), but it is not clear which size of particles are most responsible for adverse heath outcomes. A current hypothesis is that ultrafine particles with diameter less than 0.1 µm are particularly harmful because their small size allows them to deeply penetrate the lungs. This paper investigates the association between exposure to particles of varying diameter and daily mortality. We propose a new dynamic factor analysis model to relate the ambient concentrations of several sizes of particles with diameters ranging from 0.01 to 0.40 µm with mortality. We introduce a Bayesian model that converts ambient concentrations into simulated personal exposure using the EPA's Stochastic Human Exposure and Dose Simulator, and relates simulated exposure with mortality. Using new data from Fresno, CA, we find that the 4‐day lag of particles with diameter between 0.02 and 0.08 µm is associated with mortality. This is consistent with the small particles hypothesis. Copyright © 2008 John Wiley & Sons, Ltd.
The distribution of Voronoi cells generated by Southern California earthquake epicenters
Authors: Schoenberg Frederic Paik , Barr Christopher , Seo Jungju 
Published: April 2008

AbstractThe cells of Voronoi diagrams generated by epicentral locations of Southern California earthquakes are inspected. The tapered Pareto distribution is shown to fit quite well to the distribution of cell areas and perimeters. This same distribution, which has been used to model the distribution of seismic moments, is also a close approximation to the empirical distributions of times and distances between successive earthquakes for the same catalog of Southern California events. Verification is performed using a variety of different windows and sub‐sampling procedures in order to confirm that the results are not an artifact of the particular parameters of the selected earthquake catalog. Copyright © 2008 John Wiley & Sons, Ltd.
A quantal statistical isobologram model to identify joint action for chemical mixtures
Authors: Chen D. G. 
Published: April 2008

AbstractThe isobologram model is a commonly used and powerful graphical and statistical tool for analyzing the joint action for simple chemical mixtures. Substantial research has been done for the quantitative response and the amount of research in the qualitative framework is minuscule. In this paper, isobologram model is proposed to analyze the joint action of chemical mixtures for quantal dose‐response relationship based on the generalized linear model technique to estimate the associated parameters by the maximum likelihood estimation and then to be used to construct the isobologram so that the joint action from the chemicals can be identified both by the isobologram and the statistical inference for interaction parameter. A real dataset is used to illustrate the application of the developed approach. Copyright © 2008 John Wiley & Sons, Ltd.
Simple confidence intervals for lognormal means and their differences with environmental applications
Authors: Zou G. Y. , Huo Cindy Yan , Taleban Julia 
Published: April 2008

AbstractThe lognormal distribution has frequently been applied to approximate environmental data, with inference focusing on arithmetic means. Confidence interval estimation involving lognormal means in small to moderate sample sizes has received much attention over the years without a simple procedure in sight. We therefore propose a closed‐form procedure for constructing confidence intervals for a lognormal mean and a difference between two lognormal means. The advantage of our procedure is that it only requires confidence limits for a normal mean and variance. The results of a numerical study show that our method performs as well as the generalized confidence interval (GCI) approach, which relies completely on computer simulation. Two real datasets are used to illustrate the methodology. Copyright © 2008 John Wiley & Sons, Ltd.
Instability investigation of cantilevered seacliffs
Authors: Young Adam P. , Ashford Scott A. 
Published: April 2008

AbstractWave action is a fundamental mechanism in seacliff erosion, whereby wave undercutting creates an unstable cantilevered seacliff profile and can lead to large catastrophic cliff failures, thus threatening coastal infrastructure. This study investigated the instability of two such failures that occurred in Solana Beach, California, by combining terrestrial LIDAR scanning, cantilever beam theory and finite element analysis. Each landslide was detected by evaluating the surface change between subsequent high resolution digital terrain models derived from terrestrial LIDAR data. The dimensions of failed cantilever masses were determined using the surface change measurements and then incorporated into failure stress analysis. Superimposing stress distributions computed from elastic cantilever beam theory and finite element modeling provided a method to back‐calculate the maximum developed tensile and shear stresses along each failure plane. The results of the stress superposition revealed that the bending stresses caused by the cantilevered load contributed the majority of stress leading to collapse. Both shear and tensile failure modes were investigated as potential cliff failure mechanisms by using a comparison of the back‐calculated failure stresses to material strengths found in laboratory testing. Based on the results of this research, the tensile strength of the cliff material was exceeded at both locations, thus causing the cliffs to collapse in tension. Copyright © 2008 John Wiley & Sons, Ltd.
Defining and measuring braiding intensity
Authors: Egozi Roey , Ashmore Peter 
Published: April 2008

AbstractGeomorphological studies of braided rivers still lack a consistent measurement of the complexity of the braided pattern. Several simple indices have been proposed and two (channel count and total sinuosity) are the most commonly applied. For none of these indices has there been an assessment of the sampling requirements and there has been no systematic study of the equivalence of the indices to each other and their sensitivity to river stage. Resolution of these issues is essential for progress in studies of braided morphology and dynamics at the scale of the channel network.A series of experiments was run using small‐scale physical models of braided rivers in a 3 m ∞ 20 m flume. Sampling criteria for braid indices and their comparability were assessed using constant‐discharge experiments. Sample hydrographs were run to assess the effect of flow variability.Reach lengths of at least 10 times the average wetted width are needed to measure braid indices with precision of the order of 20% of the mean. Inherent variability in channel pattern makes it difficult to achieve greater precision. Channel count indices need a minimum of 10 cross‐sections spaced no further apart than the average wetted width of the river. Several of the braid indices, including total sinuosity, give very similar numerical values but they differ substantially from channel‐count index values. Consequently, functional relationships between channel pattern and, for example, discharge, are sensitive to the choice of braid index. Braid indices are sensitive to river stage and the highest values typically occur below peak flows of a diurnal (melt‐water) hydrograph in pro‐glacial rivers. There is no general relationship with stage that would allow data from rivers at different relative stage to be compared. At present, channel count indices give the best combination of rapid measurement, precision, and range of sources from which measurements can be reliably made. They can also be related directly to bar theory for braided pattern development. Copyright © 2008 John Wiley & Sons, Ltd.
Historic and contemporary sediment transfer in an upland Pennine catchment, UK
Authors: Holliday V. J. , Warburton J. , Higgitt D. L. 
Published: April 2008

AbstractA sediment budget for an upland catchment–reservoir system at Burnhope Reservoir, North Pennines, UK has been developed. This provides a framework for quantifying historic and contemporary sediment yields and drainage basin response to disturbance from climate change and human activities in the recent past. Bathymetric survey, core sampling, 137Cs dating and aerial photographs have been used to assess sediment accumulation in the reservoir. The average reservoir sedimentation rate is 1·24 cm yr−1 (annual sediment yield 33·3 t km−2 yr−1 ± 10%, trap efficiency 92%). Mean annual reservoir sedimentation over the 67 year period has been estimated at 592 t ± 10%. Inputs of suspended sediment from direct catchwater streams account for 54% of sediment supply to the budget (best estimate yield of 318 t yr−1 ± 129%), while those from actively eroding reservoir shorelines contribute 328 t yr−1 ± 92%. Sediment yield estimates from stream monitoring and reservoir sedimentation are an order of magnitude lower than those reported from South Pennine reservoirs of comparable drainage basin area. Analysis of historical rainfall series for the catchment shows fluctuations in winter and summer rainfall patterns over the past 62 years. From 1976 to 1998 there has been a diverging trend between winter and summer rainfall, with a large increase in winter and a gradual decrease in summer totals. Periods of maximum variation occur during the summer drought events of the late 1970s, early 1980s and mid‐1990s. Analysis of the particle size of core sediments highlights abrupt increases in sand‐sized particles in the top 20 cm of the core. Based on the 137Cs chronology, these layers were deposited from the late 1970s onwards and relate to these diverging rainfall records and rapidly fluctuating reservoir levels. This provides evidence of potential sediment reworking within the reservoir by rapid water‐level rise after drought. Copyright © 2008 John Wiley & Sons, Ltd.
Code‐aided simplified receiver design in downlink MC‐CDMA communication system with transmit diversity
Authors: Wu Wei‐Chiang 
Published: April 2008

AbstractIn this paper, we propose a code‐aided optimum receiver and exploit transmit diversity in downlink multicarrier code division multiple access (MC‐CDMA) system to provide a receiving scheme that is robust to fading channel. Our first emphasis is on designing a blind (without knowing the undesired users' signature sequences) MC‐CDMA mobile receiver that can suppress the multiple access interference (MAI) and combine the desired signal stemmed from all the transmitting antennas. The matched filter (MF) receiver, though simple in structure, suffers from the near‐far problem and is severely degraded by MAI. The minimum‐output‐energy (MOE) receiver, though alleviates the problems of the MF receiver, is with computational complexity and suffers from severe performance degradation due to channel estimation error in practical environment. Thereby, we propose a spreading codes selection rule that enables the simple MF receiver to achieve optimum performance regardless of the variation of channel parameters. Moreover, we develop two blind (without requiring training sequences) algorithms to estimate the composite multiple‐inputs‐single‐output (MISO) channel impulse response (IR). Furthermore, we deduce that the complexity of the channel estimator can be extensively reduced for the code‐aided optimum receiver. Simulation results demonstrate significant gain by employing the proposed codes selection rule and transmit diversity. Copyright © 2008 John Wiley & Sons, Ltd.
Enhanced detection of genetic association of hypertensive heart disease by analysis of latent phenotypes
Authors: Charles Gu C. , Flores Hubert R. , de las Fuentes Lisa , Dávila‐Román Victor G. 
Published: April 2008

AbstractHypertension and hypertensive heart disease (HHD) are inter‐related phenotypes frequently observed with other comorbidities such as diabetes, obesity, and dyslipidemia, which probably reflect the complex gene‐gene and/or gene‐environment interactions resulting in HHD. The complexity of HHD led us to examine intermediate phenotypes (e.g., echocardiographically‐derived measures) for simpler clues to the genetic underpinnings of the disease. We applied the method of independent component analysis to a prospective study of the metabolic predictors of left ventricular hypertrophy and extracted latent traits of HHD from panels of multi‐dimensional anthropomorphic, hemodynamic echocardiographic and metabolic data. Based on the latent trait values, classification of subjects into different risk groups for HHD captured meaningful subtypes of the disease as reflected in the distributions of primary clinical indicators. Furthermore, we detected genetic associations of the latent HHD traits with single nucleotide polymorphisms in three candidate genes in the peroxisome proliferator‐activated receptors complex, for which no significant association was found with the original clinical indicators of HHD. Consensus analysis of the results from repeated independent component analysis runs showed satisfactory robustness and estimated about 3–4 separate unseen sources for the observed HHD‐related outcomes. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
Orphan drug legislation: lessons for neglected tropical diseases
Authors: Villa Stefano , Compagni Amelia , Reich Michael R. 
Published: April 2008

AbstractIn the last 20 years, orphan drug legislation (ODL) has been adopted in several countries around the world (USA, Japan, Australia, and the European Union) and has successfully promoted R&D investments to develop new pharmaceutical products for the treatment of rare diseases. Without these incentives, many life‐saving new drugs would have not been developed and produced.For economic reasons, the development of medicines for the treatment of diseases prevalent in the developing world (or tropical diseases) is lagging behind. Among several factors, the low average per‐capita income makes pharmaceutical markets in developing countries appear relatively unprofitable and therefore unattractive for R&D‐oriented companies.The case of ODL may offer some useful insights and perspectives for the fight against neglected tropical diseases. First, the measures used in ODL may also be effective in boosting R&D for neglected tropical diseases, if appropriately adapted to this market. Second, small‐sized companies, which have played a successful role in the development of orphan drugs for rare diseases, may also represent a good business strategy for the case of tropical diseases. Copyright © 2008 John Wiley & Sons, Ltd.
Measuring and managing progress in the establishment of basic health services: the Afghanistan health sector balanced scorecard
Authors: Hansen Peter M. , Peters David H. , Niayesh Haseebullah , Singh Lakhwinder P. , Dwivedi Vikas , Burnham Gilbert 
Published: April 2008

AbstractThe Ministry of Public Health (MOPH) of Afghanistan has adopted the Balanced Scorecard (BSC) as a tool to measure and manage performance in delivery of a Basic Package of Health Services. Based on results from the 2004 baseline round, the MOPH identified eight of the 29 indicators on the BSC as priority areas for improvement. Like the 2004 round, the 2005 and 2006 BSCs involved a random selection of more than 600 health facilities, 1700 health workers and 5800 patient‐provider interactions. The 2005 and 2006 BSCs demonstrated substantial improvements in all eight of the priority areas compared to 2004 baseline levels, with increases in median provincial scores for presence of active village health councils, availability of essential drugs, functional laboratories, provider knowledge, health worker training, use of clinical guidelines, monitoring of tuberculosis treatment, and provision of delivery care. For three of the priority indicators—drug availability, health worker training and provider knowledge—scores remained unchanged or decreased between 2005 and 2006. This highlights the need to ensure that early gains achieved in establishment of health services in Afghanistan are maintained over time. The use of a coherent and balanced monitoring framework to identify priority areas for improvement and measure performance over time reflects an objectives‐based approach to management of health services that is proving to be effective in a difficult environment. Copyright © 2008 John Wiley & Sons, Ltd.
Identifying the differential effects of silymarin constituents on cell growth and cell cycle regulatory molecules in human prostate cancer cells
Authors: Deep Gagan , Oberlies Nicholas H. , Kroll David J. , Agarwal Rajesh 
Published: April 2008

AbstractProstate cancer (PCa) is the leading cause of cancer‐related deaths in men; urgent measures are warranted to lower this deadly malignancy. Silymarin is a known cancer chemopreventive agent, but the relative anticancer efficacy of its constituents is still unknown. Here, we compared the efficacy of 7 pure flavonolignan compounds isolated from silymarin, namely silybin A, silybin B, isosilybin A, isosilybin B, silydianin, isosilydianin, silychristin and isosilychristin, in advanced human PCa PC3 cells. Silybin A, silybin B, isosilybin A, isosilybin B, silibinin and silymarin strongly inhibited the colony formation by PC3 cells (p < 0.001), while silydianin, silychristin and isosilychristin had marginal effect (p < 0.05). Using cell growth and death assays, we identified isosilybin B as the most effective isomer. FACS analysis for cell cycle also showed that silybin A, silybin B, isosilybin A, isosilybin B, silibinin and silymarin treatment resulted in strong cell cycle arrest in PC3 cells after 72 hr of treatment, while the effect of silydianin, silychristin and isosilychristin was marginal (if any). Western blot analysis also showed the differential effect of these compounds on the levels of cell cycle regulators‐cyclins (D, E, A and B), CDKs (Cdk2, 4 and Cdc2), CDKIs (p21 and p27) and other cell cycle regulators (Skp2, Cdc25A, B, C and Chk2). This study provided further evidence for differential anticancer potential among each silymarin constituent, which would have potential implications in devising better formulations of silymarin against prostate and other cancers. © 2008 Wiley‐Liss, Inc.
Towards accurate in vivo spectroscopy of the human prostate
Authors: Svensson Tomas , Alerstam Erik , Einarsdóttír Margrét , Svanberg Katarina , Andersson‐Engels Stefan 
Published: April 2008

AbstractThe recent interest in photodynamic therapy of human prostate cancer is accompanied by a need for techniques for in vivo monitoring of optical and physiological characteristics. We propose time‐of‐flight (TOF) spectroscopy in combination with Monte Carlo evaluation as a reliable optical technique for quantitative assessment of absorption, scattering, hemoglobin content and tissue oxygenation in the human prostate. For the first time, we demonstrate Monte Carlo‐based evaluation of in vivo TOF photon migration data. We show that this approach is crucial in order to avoid the large errors associated with the use of time‐resolved diffusion theory of light propagation in prostate‐like tissues. This progress also allows us to present the first in vivo scattering spectroscopy of human prostate tissue. Furthermore, TOF spectroscopy, in contrast to the more common steady‐state approach, is insensitive to bleedings, and has been found highly reliable (100% success rate). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction of Sr‐doped hydroxyapatite nanocrystals with osteoclast and osteoblast‐like cells
Authors: Capuccini C. , Torricelli P. , Boanini E. , Gazzano M. , Giardino R. , Bigi A. 
Published: April 2008

AbstractThis article reports the effect of strontium incorporation into hydroxyapatite nanocrystals on bone cells response. Hydroxyapatite nanocrystals were synthesized at strontium contents of 0, 1, 3, 7 atom %. Strontium incorporation for calcium is confirmed by the linear increase of the unit cell parameters of hydroxyapatite, in agreement with the different ionic radii of the two ions. Moreover, strontium substitution slightly affects hydroxyapatite structural order and the shape of the nanocrystals. Osteoblast‐like MG63 cells cultured on the nanocrystals display good proliferation and increased values of the differentiation parameters. In particular, when cultured on samples with Sr concentration in the range 3–7 atom %, osteoblasts display increased values of ALP activity, collagen type I, and osteocalcin production. Moreover, the osteoclast number on all the Sr‐doped samples is significantly smaller than on hydroxyapatite, and it decreases on increasing strontium content. The data indicate that strontium stimulates osteoblast activity and exerts its inhibitory effect on osteoclast proliferation even when incorporated into hydroxyapatite. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
A library of tunable poly(ethylene glycol)/poly(L‐lysine) hydrogels to investigate the material cues that influence neural stem cell differentiation
Authors: Hynes Sara R. , Rauch Millicent F. , Bertram James P. , Lavik Erin B. 
Published: April 2008

AbstractNeural stem cells (NSCs) have the potential to replace the major cell types of the central nervous system (CNS) and may be important in therapies for injuries to and diseases of the CNS. However, for such treatments to be safe and successful, NSCs must survive and differentiate appropriately following transplantation. A number of polymer scaffolds have shown promise in improving the survival and promoting the differentiation of NSCs. To capitalize on the interaction between scaffolds and NSCs, we need to determine the fundamental material properties that influence NSC behavior. To investigate the role of material properties on NSCs, we synthesized a library of 52 hydrogels composed of poly(ethylene glycol) and poly(L‐lysine) (PLL). This library of hydrogels allows independent variation of chemical and mechanical properties across a wide range of values. By culturing NSCs on this library, we have identified a subset of gels that promotes NSC migration and a further subset that promotes NSC differentiation. By combining the material properties of these subsets with the cell behavior, we determined that mechanical properties play a critical role in NSC behavior with elastic moduli promoting NSC migration and neuronal differentiation. Amine concentration is less critical, but PLL molecular weight also plays a role in NSC differentiation. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Bone‐like tissue formation on a biomimetic titanium surface in an explant model of osteoconduction
Authors: Isaac Juliane , Loty Sabine , Hamdan Ahmad , Kokubo Tadashi , Kim Hyun‐Min , Berdal Ariane , Sautier Jean‐Michel 
Published: April 2008

AbstractThe clinical use of titanium in dental and orthopedic applications is limited. Over recent years, implant surfaces have undergone numerous modifications to enhance bone integration. In this study, we experimented a bioactive titanium using a simple chemical and moderate heat treatment that led to the formation of a bone‐like apatite layer on its surface in simulated body fluids. We used a bone explant model to demonstrate that cells can migrate from the explants and subsequently differentiate to form a mineralized nodular structure. Furthermore, these cells expressed alkaline phosphatase, bone sialoprotein, osteocalcin and the transcription factor, Runx2. Using this model of osteoconduction, we showed that bioactive titanium bonds directly to bone, while pure titanium cannot. These findings show the importance of implant surface composition in promoting osteogenic cell differentiation and subsequent apposition of the bone matrix, allowing strong bonds to form. This model could be particularly beneficial to closely mimic bone formation adjacent to endosseous implants. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009