bluuebunny/crossref_metadata_2025_split huggingface dataset:
Attenuation estimation in thin transitional layers with gradational velocity change
Authors: Tian Gang , Cheng Suo , Shi Zhanjie , Wang Kai 
Published: August 2009

ABSTRACTIn a desert area, unconsolidated sediment can seriously attenuate the high frequency components of seismic data. In order to evaluate the attenuation of a seismic wave in the medium, we firstly analysed the primary seismic wave from up‐hole survey data acquired from the Takelamagan desert of north‐west China and then performed numerical simulations. The up‐hole results showed that there is a stratum in which the velocity increases gradually when the depth increases and where amplitudes and frequency components are attenuated and are decreased seriously by the waves being reflected or passing through the stratum. We regard the stratum as a linear transition layer. Based on the linear transition theory and the velocity structures obtained from up‐hole data, the one‐dimensional numerical simulation method was used to calculate seismograms of transmission waves and reflection waves. By analysing these two records, it was found that both amplitudes and frequency components attenuated greatly due to the existing linear transition layer. This can be interpreted as scattering or multiples since the reflection and the transmission actions usually occurred in this kind of stratum more than once. This is a significant factor for the amplitudes and frequency components attenuation of a partially saturated layer in a desert area. The filter character of the transition stratum can be described as a low‐pass filter for reflection waves and as a high‐pass filter for transmission waves.
The lining quality detection and grouting effect evaluation of the Kunlun Mountain railway tunnel using ground‐penetrating radar
Authors: Zhang Li , Liu Zhengping , Gong Chengming 
Published: August 2009

ABSTRACTThe ground‐penetrating radar (GPR) method is increasingly applied to the quality evaluation of large‐scale civil engineering projects due to its accuracy, non‐destructive application and rapidity. In this paper, we discuss the acquisition and analysis of GPR data acquired in the Kunlun Mountain railway tunnel, China. We evaluate the tunnel lining quality and detect the hidden flaws in the lining, which are used to direct the subsequent grouting. Finally, GPR is used to assess the quality of the grouting. The results verify the flexibility and effectiveness of this method.
The role of geomagnetic methods in the detection of mineral deposits at El‐Hody area, south‐eastern Aswan, Egypt
Authors: Rabeh T. , El Faragawy K.O. , Miranda J.M. , Monteiro Santos F.A. , Ahmed M. 
Published: August 2009

ABSTRACTIn this study we delineate the subsurface structures within an area of about 840 km2 in south‐western Egypt, using magnetic methods. The main target is to establish the tectonic framework of the studied area and to understand the role of tectonics in the mineralization process. To do so, a land magnetic survey was conducted, complemented with available aeromagnetic data. This data set is processed using a series of techniques, namely, trend analysis, Werner deconvolution and 2.5 direct modelling. Results indicate that the most predominant tectonic trends are NW–SE, NE–SW and E–W directions. The depth to the basement rocks ranges from 0 to 1.3 km. These results agree with the drilled well data. We show a good correlation between the structures deduced from the magnetic analysis and the known mineral distributions. We conclude that mineralization is structurally controlled by faulting, probably as the result of hydrothermal circulation on fault planes.
Investigation of underground cavities in a two‐layer model using the refraction seismic method
Authors: Engelsfeld Tihomir , Šumanovac Franjo , Pavin Nenad 
Published: August 2009

ABSTRACTThis paper presents a new approach to the investigation of underground cavities. Our technique is based on the refraction seismic method. We have studied a two‐dimensional, two‐layer geological model. In our model, the lower seismic velocity layer is situated above the higher seismic velocity layer, with a circular cavity positioned within the upper layer. We have investigated the influence exerted by the cavity on the first arrivals of seismic waves. The obtained traveltimes are solutions of the eikonal equation and are presented using the time‐distance graph. All refracted waves encountering the cavity have to circumvent it, as it represents an impediment to the propagation of seismic energy. This circumvention causes delays in the first arrivals of the seismic waves at the surface as compared to traveltimes with no cavity present. These delays create a characteristic shape of the time‐distance graph, characterized by the peak point in which the plot line has a discontinuous change. Using this graph and analysing the delays of the first arrivals, we have derived expressions for determining both the position and size of the circular cavity. The practical application of the derived relations has been tested on a model test site built in a natural rock setting. This simple method indicates the presence of the cavity. The accuracy of the calculated cavity parameters: the horizontal position , the depth and cavity radius depends on the geophone spacing. For geophone spacing equal to or less than the cavity radius, the accuracy of the method is shown to be acceptable. The maximal estimated error is equal to a half geophone spacing. Finally, we have demonstrated that this method is also applicable in the detection of non‐circular cavities.
Geotechnical analysis and 4D GPR measurements for the assessment of the risk of sinkholes occurring in a Polish mining area
Authors: Marcak Henryk , Golebiowski Tomislaw , Tomecka‐Suchon Sylwia 
Published: August 2009

ABSTRACTThe study presented in this paper concerns georadar investigations at a selected former coal mining site in Upper Silesia (Poland) where the risk of sinkhole appearance is high. The results of 3D GPR surveys obtained in three measurement sessions in December 1997, October 2006 and March 2007 were interpreted. The 4D interpretation, i.e., a time‐space analysis, allowed for the identification of loose zones in the ground and fractured zones of the rock mass, which might be a source of sinkhole creation. After the first measurement session, on the basis of the GPR survey results, a dangerous, fractured zone in the ground was localized. This zone was confirmed by a borehole. Between the second and third sessions, a large sinkhole appeared on site, as predicted on the basis of georadar investigations. The geomechanical analyses presented in this paper explain the development of the fractured zones over the earlier mining excavations. Such zones accumulate water and high contrasts of dielectrical permittivity appear, allowing the use of the GPR method for the location of these zones.
Processing and Presentation of Variant Surface Glycoprotein Molecules to T Cells in African Trypanosomiasis
Authors: Dagenais Taylor R. , Freeman Bailey E. , Demick Karen P. , Paulnock Donna M. , Mansfield John M. 
Published: August 2009

Abstract
Th1 cell responses to the variant surface glycoprotein (VSG) of African trypanosomes play a critical role in controlling infection through the production of IFN-γ, but the role of APCs in the induction and regulation of T cell-mediated protection is poorly understood. In this study, we have investigated the Ag presentation capabilities of dendritic cells (DCs) and macrophages during early trypanosome infection in relatively resistant responder and susceptible nonresponder mouse strains. Splenic DCs appeared to be the primary cell responsible for activating naive VSG-specific Th cell responses in resistant responder animals through the coordinated up-regulation of costimulatory molecules, secretion of IL-12, and presentation of VSG peptides to T cells in vivo. Splenic DC depletion and the down-regulation of costimulatory markers on splenic macrophages were observed in susceptible animals and may be associated with the inability of these animals to elicit a significant VSG-specific T cell response. In contrast to splenic APCs, peritoneal macrophages secreted NO, failed to activate naive Th cells in vitro, and presented relatively low levels of VSG peptides to T cells in vivo. Thus, VSG-specific Th1 cell responses may be determined by tissue- and cell-specific differences in Ag presentation. Additionally, all APCs from resistant and susceptible strains displayed a reduced ability to process and present newly encountered exogenous Ag, including new VSG molecules, during high parasitemia. Thus, initial uptake of VSG (or other trypanosome factors) may interfere with Ag presentation and have dramatic consequences for subsequent T cell responses to other proteins.
Modulation of Single-Cell IgG Secretion Frequency and Rates in Human Memory B Cells by CpG DNA, CD40L, IL-21, and Cell Division
Authors: Henn Alicia D. , Rebhahn Jonathan , Brown Miguel A. , Murphy Alison J. , Coca Mircea N. , Hyrien Ollivier , Pellegrin Tina , Mosmann Tim , Zand Martin S. 
Published: August 2009

Abstract
During the recall response by CD27+ IgG class-switched human memory B cells, total IgG secreted is a function of the following: 1) the number of IgG-secreting cells (IgG-SC), and 2) the secretion rate of each cell. In this study, we report the quantitative ELISPOT method for simultaneous estimation of single-cell IgG secretion rates and secreting cell frequencies in human B cell populations. We found that CD27+ IgM− memory B cells activated with CpG and cytokines had considerable heterogeneity in the IgG secretion rates, with two major secretion rate subpopulations. BCR cross-linking reduced the frequency of cells with high per-cell IgG secretion rates, with a parallel decrease in CD27high B cell blasts. Increased cell death may account for the BCR-stimulated reduction in high-rate IgG-SC CD27high B cell blasts. In contrast, the addition of IL-21 to CD40L plus IL-4-activated human memory B cells induced a high-rate IgG-SC population in B cells with otherwise low per-cell IgG secretion rates. The profiles of human B cell IgG secretion rates followed the same biphasic distribution and range irrespective of division class. This, along with the presence of non-IgG-producing, dividing B cells in CpG plus cytokine-activated B memory B cell populations, is suggestive of an on/off switch regulating IgG secretion. Finally, these data support a mixture model of IgG secretion in which IgG secreted over time is modulated by the frequency of IgG-SC and the distribution of their IgG secretion rates.
Sequential, Ordered Acquisition of Antibodies to Plasmodium falciparum Erythrocyte Membrane Protein 1 Domains
Authors: Cham Gerald K. K. , Turner Louise , Lusingu John , Vestergaard Lasse , Mmbando Bruno P. , Kurtis Jonathan D. , Jensen Anja T. R. , Salanti Ali , Lavstsen Thomas , Theander Thor G. 
Published: August 2009

Abstract
The binding of erythrocytes infected with mature blood stage parasites to the vascular bed is key to the pathogenesis of malignant malaria. The binding is mediated by members of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. PfEMP1s can be divided into groups, and it has previously been suggested that parasites expressing group A or B/A PfEMP1s are most pathogenic. To test the hypothesis that the first malaria infections in infants and young children are dominated by parasites expressing A and B/A PfEMP1s, we measured the plasma Ab level against 48 recombinant PfEMP1 domains of different groupings in 1342 individuals living in five African villages characterized by markedly different malaria transmission. We show that children progressively acquire a broader repertoire of anti-PfEMP1 Abs, but that the rate of expansion is governed by transmission intensity. However, independently of transmission intensity, Abs are first acquired to particular duffy binding ligand-like domains belonging to group A or B/A PfEMP1s. The results support the view that anti-PfEMP1 Ab responses effectively structure the expenditure of the repertoire of PfEMP1 maintained by the parasite. Parasites expressing certain group A and B/A PfEMP1s are responded to first by individuals with limited previous exposure, and the resulting Abs reduce the fitness and pathogenicity of these parasites during subsequent infections. This allows parasites expressing less pathogenic PFEMP1s to dominate during later infections. The identification of PfEMP1 domains expressed by parasites causing disease in infants and young children is important for development of vaccines protecting against severe malaria.
Genetic Control of Severe Egg-Induced Immunopathology and IL-17 Production in Murine Schistosomiasis
Authors: Smith Patrick M. , Shainheit Mara G. , Bazzone Lindsey E. , Rutitzky Laura I. , Poltorak Alexander , Stadecker Miguel J. 
Published: August 2009

Abstract
Infection with the trematode parasite Schistosoma mansoni results in a distinct heterogeneity of disease severity, both in humans and in an experimental mouse model. Severe disease is characterized by pronounced hepatic egg-induced granulomatous inflammation in a proinflammatory cytokine environment, whereas mild disease corresponds with reduced hepatic inflammation in a Th2 skewed cytokine environment. This marked heterogeneity indicates that genetic differences play a significant role in disease development, yet little is known about the genetic basis of dissimilar immunopathology. To investigate the role of genetic susceptibility in murine schistosomiasis, quantitative trait loci analysis was performed on F2 progeny derived from SJL/J and C57BL/6 mice, which develop severe and mild pathology, respectively. In this study, we show that severe liver pathology in F2 mice 7 wk after infection significantly correlated with an increase in the production of the proinflammatory cytokines IL-17, IFN-γ, and TNF-α by schistosome egg Ag-stimulated mesenteric lymph node cells. Quantitative trait loci analysis identified several genetic intervals controlling immunopathology as well as IL-17 and IFN-γ production. Egg granuloma size exhibited significant linkage to two loci, D4Mit203 and D17Mit82, both of which were inherited in a BL/6 dominant manner. Furthermore, a significant reduction of hepatic granulomatous inflammation and IL-17 production in interval-specific congenic mice demonstrated that the two identified genetic loci have a decisive effect on the development of immunopathology in murine schistosomiasis.
Biological Effects of Electromagnetic and Particle Radiation
Authors: Kiefer Jürgen 
Published: August 2009

AbstractThe article contains sections titled:IntroductionRadiation Types and SourcesInteraction with Biosystems at the Physical LevelIonizing RadiationElectromagnetic RadiationParticle RadiationOptical RadiationRadio Frequency and MicrowavesDeposition of EnergyIonizing RadiationUVand Visible RadiationInfraredRadio Frequency and MicrowavesEffects on Molecules of Biological Importance and Cell OrganellesWaterPhotochemistry and Radiation Chemistry ofDNAChromosomal AberrationsMembranesEffects of Heat TreatmentSpecific Molecular Aspects of Radio Frequency and Microwave ActionsCellular EffectsExperimental Endpoints of Cellular Radiation ActionSurvivalMutationsNeoplastic TransformationModifications of Cellular Radiation EffectsThe Temporal Pattern of ExposureChemical Protectors and SensitizersRepair ProcessesRadiation Quality“Nonclassical” Effects in Cellular Radiobiology: Bystander Effect, Genomic Instability, Low Dose Sensitivity, and Adaptive ResponseHeat Effects at the Cellular LevelSpecific Cellular Effects of Radio Frequency and MicrowavesOrgan and Whole‐Body EffectsAcute EffectsSkinEyeNervous System and Other OrgansRadiation Syndromes and LethalityRadiation and ProgenyFertilityTeratogenic EffectsGenetic EffectsRadiation CancerogenesisUltraviolet RadiationIonizing RadiationTissue and Whole‐Body Effects of Infrared RadiationTissue and Whole‐Body Effects of Radio Frequency and MicrowavesApplied Radiation BiologyMolecular TechniquesAction SpectroscopyMolecular Weight Determination by “Radiation Inactivation”Radiation Disinfection and SterilizationTherapeutic ApplicationsNonmalignant DiseasesCancer TherapyBiodosimetryFluorescenceIn situHybridization (FISH) for Chromosomal TranslocationsESRDosimetryRadioecology, Radiation Protection, and GuidelinesRadioecologyNonionizing RadiationsIonizing RadiationPrinciples of Radiation Protection RegulationsIonizing RadiationsNonionizing Radiations
Biological Effects of Sound and Ultrasound
Authors: Nyborg Wesley L. 
Published: August 2009

AbstractAt frequencies mostly in the megahertz range, ultrasound has become indispensable in diagnostic medicine. Sound over a wide frequency range is being used increasingly in therapeutic applications, including drug delivery. Much research has been carried out to study biological effects of this agent, especially, ultrasound, to seek understanding of mechanisms for them. Since sonic energy is converted into heat as it passes through tissues, temperature elevation is an important mechanism. Another important kind of mechanism, calledcavitation, is important when small gas bubbles are present, as is often true duringin vivoexposures of cell suspensions. If the pressure amplitude is modest, the action may be harmless, or even beneficial by making cells temporarily permeable allowing drug transfer. If it is high, the action may be violent and cause permanent damage. The importance of cavitation during applications of diagnostic ultrasound has greatly increased during the last decade because of the widespread use of “contrast agents”. These are small specially coated gas bubbles, which are injected into the blood of a patient to improve image contrast. Whether cavitation occurs or not during an application, sonic fields can produce effectsviatime‐averaged forces and fluid motions known asradiation forceandacoustic streaming(ormicrostreaming). The present chapter is a review of current knowledge on effects that can be produced by sonic fields and causes of these effects.
Radiationless Auger‐Like Electronic Transitions in Biomolecules: Bio‐Auger Process
Authors: Bohr Henrik G. , Malik F. Bary 
Published: August 2009

AbstractNonradiative relaxation process caused by the interaction between electrons in biomolecules following radiative absorption is discussed herein. The process is akin to Auger transitions in atoms to fill K, L, or M shell vacancies. Such Auger transitions in light elements are much faster than the radiative transition rate, and half‐lives could be in femtoseconds, as observed in many recent biomolecules being exposed to laser beams. After a brief introduction, the basic theory of Auger and electromagnetic transitions in atomic systems and the calculations based on that indicating dominance of the Auger process over the radiative one are presented in Section 2.2. The similarity and differentiation between the Auger process in atomic systems and similar ones in biomolecules, termed asBio‐Auger processes, are presented in Section 2.3. The single orbital theory and the estimate of the timescale associated with Bio‐Auger processes are noted in Section 2.4, followed by a section on charge or electronic transfer associated with the Bio‐Auger process. In the last section, experimental evidence of the occurrence of the Bio‐Auger process after biomolecules are exposed to ultraviolet (UV) radiation is presented. In particular, calculations indicating the occurrence of electronic excited states in the energy range of UV radiation are noted. It is pointed out that (i) nonradiative transitions of Bio‐Auger type might be preventing cancer in biotissues exposed to the UV part of solar radiation; (ii) dark structures reported in exposing biomolecules to laser beam are electronic charge transfer; (iii) Bio‐Auger processes may lead to charge transfer of electrons from peridinin to chlorophyll‐ain peridinin‐chlorophyll‐a protein (PCP) complex; and (iv) Bio‐Auger processes lead to de‐dimerization of thymine duplex formed in UV activated thymine bases in DNA as it comes in contact with optically activated cofactor riboflavin.
Electron Interactions and Currents in
CFT
, a Current Functional Theory Applied to Molecules
Authors: Bang Jens M. , Bohr Henrik G. , da Providencia Joao 
Published: August 2009

Abstract
Most of the quantum mechanical calculations of electronic structures of molecules are carried out in a stationary frame where the wave functions of the electrons in the molecule are optimized into a ground state configuration. If one, however, wishes to obtain a more dynamic description of molecules on the electronic level and if one wishes to find the spectrum of excited electron states, one will have to employ a time‐dependent quantum mechanical methodology. In the following sections, we introduce a time‐dependent quantum formalism that can give a dynamic treatment of the electronic systems and that can also take care of the calculation of excited states. Besides that, we shall propose rigorous expressions of exchange correlation potentials in order to get more reliable suggestions for the molecular orbitals.
Exploring Excited State Processes in Photosynthesis — Features of Photosynthetic Light Harvesting
Authors: Sundstrom Villy 
Published: August 2009

Abstract
Photosynthesis is the process by which light energy is converted into chemical energy by plants, algae, and photosynthetic bacteria. For this, highly specialized pigment–proteins have evolved, which capture the light and transform the short‐lived excited states of pigment molecules into a stable transmembrane potential. By close scrutiny of organization and processes of the photosynthetic pigment systems, a number of “design principles” can be recognized. By combining knowledge about structure and light converting energy and electron transfer processes, we can identify the most important features for efficient photosynthetic solar energy conversion.
Protein Dynamics — Concepts and Experimental Tools
Authors: Frauenfelder Hans 
Published: August 2009

AbstractMost textbooks and publications show proteins in a unique structure and naked, without hydration shell and bulk environment. In reality, proteins can assume a very large number of different conformations. They fluctuate continuously and are controlled by the hydration shell and the solvent. Without these fluctuations, proteins could not work. This chapter gives a brief overview of protein dynamics and cites references where more information can be found.
Models of Membrane Fusion
Authors: May Sylvio 
Published: August 2009

AbstractThe fusion of biomembranes is an ubiquitous event in living organisms encountered in diverse situations, such as intracellular trafficking, recycling, fertilization, and infections by enveloped viruses. Even though each specific type of biological fusion is regulated by particular fusion proteins, it always involves the merger of two lipid bilayers. Even in the absence of proteins, bare lipid bilayers can be induced to undergo fusion. The question whether different types of fusion are variants of one or several universal fusion mechanisms has received much attention, but is not finally answered. At present, the most promising candidate is the stalk‐pore fusion pathway, which involves several lipid‐based fusion intermediates. We give an overview of common fusion types, current knowledge of corresponding fusion mechanisms, and efforts to model membrane fusion. The latter includes both phenomenological modeling and computer simulations.