bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential and pitfalls of GPR traveltime tomography for ancient buildings investigation: experiments on a small‐scalem real and synthetic calcarenitic block
Authors: Nuzzo L. , Quarta T. , Galati M.B. , Fedi M. , Garofalo B. 
Published: August 2009

ABSTRACTEven if its use is not widespread in the archaeological community, GPR tomography is a viable tool in the maintenance of Cultural Heritage and for the diagnosis of internal defects in masonry, originating either at the building stage or later because of normal decay or natural disasters. Two‐dimensional GPR traveltime tomography aims to obtain information on the distribution of the dielectric constant on a section of the investigated medium from the picked direct arrival traveltimes between sources and receivers. This paper shows the results of a GPR tomographic experiment on a calcarenitic stone block with an empty central hole, using 1000 MHz as transmitter and 1800 MHz as receiver antennas. The original aims of this work were firstly, to assess the usefulness and limits of very basic tomographic tools, accessible also to the non academic community, in the limited case of locating voids in small‐scale structures (pillars or columns) and secondly, to identify possible pitfalls due to acquisition/ processing procedures or to inadequacy of the inversion algorithm. We examine some problems encountered in data acquisition and we propose a method to estimate the effective bandwidth of antenna pairs of different nominal frequencies and to estimate the zero time correction. The experiment shows that picking the first arrivals is a very delicate operation when the airwaves interfere with the transmitted ones and that using the wrong picked traveltimes in the inversion could lead to inconsistencies or to strong reconstruction artefacts. Finite‐difference numerical modelling is helpful both for identifying the correct arrivals to be picked and for exploring the dependence of the tomographic inversion on cell size, geometry of transmitters and receivers and initial model. The inversion results show a strong dependence on the angular ray coverage. The general improvement observed by increasing the illumination directions confirms the opportunity of using, whenever all sides are accessible, as in the case of columns or pillars, both parallel and orthogonal antenna positioning. In the presence of strong velocity gradients, as in this case, even using the best acquisition configuration for transmitters and receivers, the straight‐ray tomography based on the SIRT algorithm can only detect the anomaly but is unable to resolve adequately its geometry and dielectric constant. Although more time‐demanding, curved‐ray tomography or more sophisticated algorithms are therefore necessary for a better characterization of internal defects in most problems of structural assessment.
Localization of small PEC spheres by multiview/single‐frequency data
Authors: Solimene Raffaele , Buonanno Aniello , Pierri Rocco 
Published: August 2009

ABSTRACTThe problem of determining the number and the locations of perfect electric conducting small spheres from the knowledge of their scattered far‐field is addressed. A multistatic/multiview/single‐frequency configuration is considered. The multiple scattering between the spheres is neglected in the problem formulation and the scatterers’ locations are represented as the support of (δ‐functions. This allows us to cast the problem as the inversion of a linear integral operator with the (δ‐functions being the actual unknowns of the problem. The inversion of such a linear integral operator is achieved by means of the truncated‐singular value decomposition. The performances achievable by the inversion algorithm are checked by synthetic exact data against model error and an additive white Gaussian noise.
The reconstruction of inhomogeneous targets from single view transient data
Authors: Belkebir K. , Catapano I. , Geffrin J.‐M. 
Published: August 2009

ABSTRACTThis paper addresses the problem of characterizing scattering systems from the knowledge of transient scattered fields measured when only one source is used to illuminate an investigating region. The inverse problem is formulated in the frequency domain rather than in the time domain and the modified2 conjugate gradient method, which is a hybrid strategy belonging to the class of the modified conjugate gradient approaches, is exploited to retrieve the unknown permittivity and/or conductivity profiles. The aim of the paper is to investigate how the reconstruction capabilities of the adopted inversion procedure may be improved by acting on the characteristic parameters of the incident pulse that is its central frequency and bandwidth. In order to provide a preliminary analysis, experimental data corresponding to inhomogeneous two‐dimensional objects embedded into a homogenous medium are processed.
Practical representations of electromagnetic interferometry for GPR applications: a tutorial
Authors: Slob Evert , Slob Evert 
Published: August 2009

ABSTRACTStarting from the reciprocity theorems of the time‐convolution and time‐correlation types, several exact interferometric representations for electric and magnetic field Green’s functions due to electric dipole and quadrupole sources are derived. The abundance of ambient noise, over a wide electromagnetic spectrum from sources in the atmosphere or in space, is used to define three different practical acquisition geometries that can be used to create new data from cross‐correlations of the noise recordings. Similar setups are given for band limited transient sources to create new data from cross‐correlations or cross‐convolutions of the recordings from these transient sources. In all these applications the Earth can be arbitrarily anisotropic and dissipative as long as one receiver is located at the Earth’s surface or in the air above. In applications where both receivers are located in the Earth we show that cross‐correlations of such recordings lead to accurate new GPR data when the Earth is almost lossless.
A time frequency domain feature extraction algorithm for landmine identification from GPR data
Authors: Lopera Olga , Milisavljević Nada , Daniels David , Gauthier Alain , Macq Benoît 
Published: August 2009

ABSTRACTGround‐penetrating radar (GPR) is a promising technique for demining procedures since it is able to detect both plastic and metal cased antipersonnel landmines. Yet, landmine identification using GPR is a challenging task since other buried reflectors such as stones or metallic debris can be detected. In this paper, a target discrimination approach is analysed and tested experimentally. It is based on relevant features extracted from 1D, GPR signals in the time frequency domain using the Wigner‐Ville distribution. Firstly, a filtering algorithm is applied to remove unwanted reflections from the background (e.g., soil surface reflection). Secondly, the preprocessed signal is transformed into a time frequency image using the Wigner‐Ville distribution. Finally, relevant features are extracted based on the singular value decomposition of the time frequency distribution. The algorithm is tested on radar data collected using two different hand‐held systems: (i) an impulse GPR‐based dual‐sensor system and (ii) a stepped‐frequency continuous‐wave GPR. Data were acquired over different types of soil and for different landmines and objects. Results are compared to features extracted using the wavelet transform and the Wilk’s lambda value is used as a criterion for optimal discrimination. Promising results are obtained, which show that time frequency features from Wigner‐Ville distribution could be used for differentiating between landmines and false alarms and could contain more valuable information than the features extracted using wavelet transform.
Biorheology
Authors: Dietrich Bauer Rudolf , Volk Tilmann 
Published: August 2009

AbstractThe article contains sections titled:IntroductionRheological ConceptsBasic Constitutive EquationsViscoelastic ModelsTransient TestsOscillatory TestsPressure–Volume RelationshipsPressure–Flow RelationshipsLaminar FlowTurbulent FlowOscillatory FlowRheology of Body FluidsViscosity of Non‐Newtonian FluidsInstrumentationRheology of BloodMacrorheologyMicrorheologyRheology of Viscoelastic Body FluidsHemodynamicsHeart MechanicsEvents of the Cardiac CycleRheological Properties of the HeartRheological Approaches to ArteriesQuasistatic Mechanical Properties of ArteriesDynamic Mechanical Properties of ArteriesPressure and Flow in the Vascular SystemSystemic ArteriesPulmonary SystemArterial DynamicsPressure and Flow in VeinsPneumodynamicsFunctional Anatomy of the LungsAirwaysLung VolumesVentilationMechanics of BreathingMechanics of InspirationMechanics of ExpirationRheology of the Respiratory TractRheology of the LungRheology of the ChestRheology of the Lung–Chest SystemAir Flow in the Respiratory TractIntrapulmonary PressureDistribution of Airway ResistancesPressure–Air Flow RelationshipAcronyms
Excited State Dynamics in Biomolecules
Authors: Groenhof Gerrit , Schäfer Lars V. , Boggio‐Pasqua Martial , Robb Michael A. 
Published: August 2009

Abstract
Organisms have evolved a wide variety of mechanisms to utilize and respond to light. In many cases, the biological response is mediated by structural changes that follow photon absorption. These reactions typically occur at femto‐ to picosecond timescales. As the relevant time and spatial resolutions are notoriously hard to access experimentally, molecular dynamics (MD) simulations are the method of choice to study such ultrafast processes.
In the simulations, a multiconfigurational quantum mechanical (QM) description (CASSCF, CASPT2) is required to model the electronic rearrangement of those parts of the system that are involved in the absorption. For the remainder, typically consisting of the apoprotein and the solvent, a simple forcefield model (MM) suffices. QM/MM gradients have to be computed on‐the‐fly, and surface hopping procedures are needed to model the excited state decay. In this chapter, the computational framework underlying the atomistic simulation of photochemical events is reviewed and a few representative applications are discussed that demonstrate the validity of hybrid QM/MM approaches for photobiological reactions.
Protein–Lipid Interactions in Biological Membranes
Authors: Nielsen Claus Helix 
Published: August 2009

AbstractThe canonical Singer–Nicolson model of lipid bilayers with embedded proteins emphasize the passive barrier properties of the bilayer component. It is, however, becoming increasingly clear that the notion of bilayers as essentially inert two‐dimensional sheets of liquid hydrocarbon is problematic. There is increasing evidence for regulation of integral membrane protein function by the molecular composition of the bilayer matrix. In many cases, the regulation is nonspecific in the sense that the regulation is coupled to a physical property of the bilayer such as equilibrium thickness and spontaneous monolayer curvature. This regulation can be rationalized by considering the hydrophobic matching between proteins and the lipid bilayer. Thus, whenever an integral membane protein undergoes a conformational change involving its hydrophobic transmembrane moiety, part of the free energy associated with the conformational change is determined by the physical properties of the lipid bilayer. This chapter first reviews the basic structural properties of lipid bilayers and the two main structural classes of integral membrane proteins: alpha‐helical bundles and beta‐barrels. Then, examples of recent advances in electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopy revealing structural and orientational information about integral membrane protein in fluid lipid bilayers are presented. Finally, a continuum elastic description of protein–lipid interactions is presented with emphasis on how to quantify the energetics of protein–lipid interactions.
Single Molecule Biophysics with Fluorescence
Authors: Prummer Michael , Huebner Christian 
Published: August 2009

AbstractWe give an overview of the physical basics, experimental techniques, and selected applications of single molecule fluorescence in biophysical research. The photophysical principles underlying single molecule fluorescence resonance energy transfer (smFRET) experiments are treated. Its application in protein biophysics, in particular protein folding and conformational dynamics associated with enzymatic activity, is outlined with selected model systems.
SMB chromatography design using profile advancement factors, miniplant data, and rate‐based process simulation
Authors: Feist Shawn D. , Hasabnis Yogesh , Pynnonen Bruce W. , Frank Timothy C. 
Published: August 2009

AbstractThis article describes a systematic miniplant‐based approach to rapid development of simulated moving bed (SMB) chromatography applications. The methodology involves analysis of single‐column pulse tests to screen adsorbents and operating conditions and to determine initial values of profile advancement factors used to specify flow rates for an initial SMB miniplant experiment. A lumped‐parameter linear driving force rate‐based model is developed by fitting process data from a single miniplant run. The data are fit in a two‐step procedure involving initial determination of effective adsorption isotherm constants as best‐fit parameters with subsequent adjustment of calculated mass transfer coefficients to refine the data fit. The resulting simulation is used to guide further miniplant work and minimize experimental effort. The methodology is illustrated with miniplant data for a binary protein separation showing excellent agreement between model results and process data generated over a wide range of operating conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Classifying functional manifestations of ectodermal dysplasias
Authors: Simeonsson Rune J. 
Published: August 2009

AbstractEctodermal dysplasias (ED) encompass more than 200 conditions involving some combination of disorders of hair, nails, teeth, and sweat glands. The incidence of ED is relatively rare affecting about 7 of 10,000 births [Itin and Fistarol (2004)]. Individuals manifesting ED present with a wide range of disorders involving hair, nails, teeth, and sweat glands and in many cases other characteristics as well. The complex nature of the disorder has presented challenges for clinical practice and required the involvement of multiple approaches and disciplines. It has also resulted in significant research initiatives on cause and symptomatology. A significant challenge has been the search for comprehensive documentation of the varied and complex manifestations associated with ED. Existing classification systems of ED have focused on physiological and structural dimensions. Classification approaches with a broader focus including characteristics of functioning in persons with ED could facilitate clinical work and research initiatives. In this context, the potential utility of available classifications that address functioning and disability would be appropriate to consider in the search for a consensus classification of ED. To that end, the purpose of this article is to (a) review the status of classification of ED, (b) provide a brief overview of the International Classification of Functioning, Disability and Health‐Children and Youth, ICF‐CY [World Health Organization (2007); International Classification of Functioning, Disability and Health‐Children and Youth. Geneva: WHO.], and (c) identify possible contributions of the ICF‐CY to classification of ED's. © 2009 Wiley‐Liss, Inc.
Synthesis, structural characterization and electrochemical recognition of metal ions of two new ferrocenylhydrazone‐based receptors
Authors: Qiao Chunjie , Li Jie , Xu Yan , Guo Shuyan , Qi Xue , Fan Yaoting 
Published: August 2009

AbstractTwo new ferrocenylhydrazone‐based receptors FcL1 and FcL2 were prepared and the X‐ray crystal structure of FcL1 was described. The electrochemical studies reveal that the receptor FcL1 is responsive to Hg2+ and Cr3+, whereas, receptor FcL2 only responsive to Hg2+. The maximum electrochemical shift of FcL1 for Cr3+ is about 56 mV. Copyright © 2009 John Wiley & Sons, Ltd.
Influence of the filler CaCO3 on the cure kinetic of the epoxy network diglycidyl ether of bisphenol a (BADGE n = 0) with isophorone diamine
Authors: Fraga Francisco , Vázquez Ivan , Rodríguez‐Núñez Eugenio , Martínez‐Ageitos José Manuel , Miragaya Javier 
Published: August 2009

AbstractThe influence of the presence of CaCO3 on the cure reaction of the epoxy network diglycidyl ether of bisphenol A with isophorone diamine has been studied. The total enthalpy of reaction, the glass transition temperature and the partial enthalpies at different isothermal temperatures have been determined using differential scanning calorimetry (DSC) in dynamic and isothermal mode. A kinetic model accounting the influence of the diffusion of the reactive groups at high conversions was used. All the kinetic parameters have been compared with those of the system without filler (CaCO3). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Ultrastructure Changes of Cardiac Lymphatics During Cardiac Fibrosis in Hypertensive Rats
Authors: Li Xiaodong , Shimada Tatsuo , Zhang Yafang , Zhou Xianli , Zhao Linghui 
Published: August 2009

AbstractHypertension is one of the most common diseases that induce a series of pathological changes in different organs of the human body, especially in the heart. There is a wealth of evidence about blood vessels in hypertensive myocardium, but little is known about structural changes in the cardiac lymphatic system. To clarify the changes in structure of the cardiac lymphatic system during hypertension, we developed a hypertension animal model with Dahl S rats and we used Dahl R rats as the control group. We examined the expression of collagen fibers, atrial natriuretic peptide, connexin43, and LYVE‐1 in the rat heart by immunohistochemistry. The ultrastructure of the cardiac lymphatics was detected by transmission electron microscopy and scanning electron microscopy. We demonstrated extensive lymphatic fibrosis in the hearts of the Dahl S hypertension group, characterized by increased thin collagen fibrils that connected with the lymphatics directly. Ultrastructural changes in the cardiac lymphatic endothelium such as an increase of vesicles and occurrence of vacuoles, active exocytosis, and cytoplasmic processes, restored the draining of tissue fluid. Our study suggests that during hypertension, the changes in structure of the cardiac lymphatics may be one important factor involved in cardiac fibrosis. Therefore, the lymphatics may be a possible target for reducing fibrosis in the treatment of hypertension. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
Interactions of Serotoninergic, Cholinergic, and Tachykinin‐Containing Nerve Elements in the Rabbit Small Intestine
Authors: Dénes Viktoria , Wilhelm Marta , NÉMeth Agnes , GÁBriel Robert 
Published: August 2009

AbstractThis report presents novel results on the effects of serotonin (5‐HT) on longitudinal muscle contractions in the rabbit ileum and the interactions of serotonin with some neuronal elements of the myenteric plexus. We showed previously that serotonin‐triggered contractions involved two mechanisms in the rabbit ileum: neuronal excitation (via 5‐HT2receptors in the neurons) and direct muscular stimulation (via 5‐HT4receptors in the muscle). Here, we focus on the neuronal 5‐HT2receptor pathway and report further pharmacological and immunocytochemical data clarifying the details of the mechanisms. We observed that antagonists for neurokinin (NK1 and NK2) receptors partially blocked the serotonin response, but NK3 receptor antagonists had no effect. Pretreatment by atropine (ATR) eliminated the NK1 receptor antagonist resistant contractions. In contrast, the NK1 antagonist did not depress the ATR‐resistant contraction when ATR was added first. 5‐HT2receptor agonist‐induced contractions were partially suppressed by ATR, hexamethonium, and NK1 or NK2 receptor antagonists. In conclusion, serotonin acting through 5‐HT2receptors could stimulate interneurons and excitatory motor neurons. Immunocytochemical staining revealed an extensive tachykinin‐immunoreactive (IR) network in the myenteric plexus. Approximately 52% of all myenteric neurons were labeled. 5‐HT‐IR fibers could be detected around both choline acetyltransferase‐ and tachykinin‐IR cells, suggesting functional relationships between them. Consistent with our pharmacological observations, we found that immunopositive nerve elements for 5‐HT2Areceptor and double‐labeled immunostaining revealed a remarkable overlap between tachykinin‐IR neurons and 5‐HT2A‐IR elements. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
Microbioreactor array for full‐factorial analysis of provision of multiple soluble factors in cellular microenvironments
Authors: Titmarsh Drew , Cooper‐White Justin 
Published: August 2009

AbstractWe report a scalable microbioreactor architecture which uses nested dilution structures to generate a full‐factorial array of cell culture conditions. The proof‐of‐concept microbioreactor array produces all combinations of three concentration levels of two soluble factors (32 = 9 unique conditions in total). The full‐factorial design is especially useful in optimizing soluble factor treatments and elucidating interaction effects between factors which are otherwise difficult to deconvolute. By nesting hierarchical levels of dilution structures, and designing the device purely by resistive flow (no valves are required), suitable diffusive mixing of growth factors up to 40 kDa is achieved such that the nine culture conditions can be generated and maintained from a minimal number of stock solutions. Biotechnol. Bioeng. 2009; 104: 1240–1244. © 2009 Wiley Periodicals, Inc.
Substrate uptake, phosphorus repression, and effect of seed culture on glycopeptide antibiotic production: Process model development and experimental validation
Authors: Maiti Soumen K. , Singh Kamaleshwar P. , Lantz Anna Eliasson , Bhushan Mani , Wangikar Pramod P. 
Published: August 2009

AbstractActinomycetes, the soil borne bacteria which exhibit filamentous growth, are known for their ability to produce a variety of secondary metabolites including antibiotics. Industrial scale production of such antibiotics is typically carried out in a multi‐substrate medium where the product formation may experience catabolite repression by one or more of the substrates. Availability of reliable process models is a key bottleneck in optimization of such processes. Here we present a structured kinetic model to describe the growth, substrate uptake and product formation for the glycopeptide antibiotic producer strain Amycolatopsis balhimycina DSM5908. The model is based on the premise that the organism is an optimal strategist and that the various metabolic pathways are regulated via key rate limiting enzymes. Further, the model accounts for substrate inhibition and catabolite repression. The model is also able to predict key phenomena such as simultaneous uptake of glucose and glycerol but with different specific uptake rates, and inhibition of glycopeptide production by high intracellular phosphate levels. The model is successfully applied to both production and seed medium with varying compositions and hence has good predictive ability over a variety of operating conditions. The model parameters are estimated via a well‐designed experimental plan. Adequacy of the proposed model was established via checking the model sensitivity to its parameters and confidence interval calculations. The model may have applications in optimizing seed transfer, medium composition, and feeding strategy for maximizing production. Biotechnol. Bioeng. 2010;105: 109–120. © 2009 Wiley Periodicals, Inc.