bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Modeling of the Slit Mode of Cavity Evolution Associated With Sand Production
Authors: Detournay C. 
Published: July 2009

Summary
This paper documents progress in the development of a numerical model to predict the amount and rate of sand production at the scale of a wellbore or perforation. The model uses a continuum hydro-mechanical description of the rock mass, coupled with a superficial erosion scheme with evolving geometry. Different modes of cavity evolution have been observed in laboratory experiments to study sand production (uniform, dog-ear, and slit), and the various modes have been associated with different rock failure types (tension, shear, and compaction). In this work, the sand-production model (which can accommodate tension and shear failure) is also expanded to account for the combination of volumetric collapse (compaction band formation) and transport of failed material by hydrodynamic forces. It is shown, using numerical experiments, that those two basic ingredients can lead to the development of the slit mechanism.
In this paper, we review the basic conditions for the compaction mode of failure to occur by considering a simple cap constitutive law and give examples of numerical simulations that illustrate band formation in a (dry) hollow cylinder test. Also, using numerical experiments, we show that the sand-production model, enhanced with a constitutive law featuring a volumetric cap, is able to reproduce qualitatively the slit mode of cavity evolution that has been observed in laboratory settings. One key feature of the computational model is a sand-production curve giving sand-mass production versus simulation time. With the documented enhancement, the model can generate sand-production curves associated with tension, shear, and compaction failure. The sand-production model needs to be developed and validated further, and calibrated using laboratory experiments. However, at this stage, it shows good potential as an engineering tool to help characterize the impact of rock strength on sand production associated with oil production.
The influence of Trisenox on actin organization in HL-60 cells
Authors: Izdebska Magdalena , Grzanka Dariusz , Gackowska Lidia , Żuryń Agnieszka , Grzanka Alina 
Published: July 2009

AbstractThe aim of this study was to show the influence of Trisenox (arsenic trioxide, ATO) on cytoplasmic and nuclear F-actin organization in HL-60 human leukemia cell line. Changes in localization were determined with the use of fluorescence microscopy and flow cytometry. Alterations, in both cytoplasmic and nuclear actin, were observed in cells exposed to ATO. F-actin network underwent accumulation and formed aggregates, that were very often placed under the cell membrane in whole cells and at the periphery of isolated nuclei. Addition of ATO also induced apoptosis and a decrease in G2 phase cells. These results suggest the influence of actin on the formation of apoptotic bodies and also participation of this protein in apoptotic alterations within nuclei, i.e. chromatin reorganization.
Occurrence and chemical diversity of the genus Bryoria in the Sučí Potok Valley, Veporské Vrchy Mountains (Central Slovakia)
Authors: Lukáč Miloš 
Published: July 2009

AbstractFour species of the genus, Bryoria were found in the Sučí Potok Valley: B. capilaris (Ach.) Brodo & D. Hawksw., B. fuscescens (Gyeln.) Brodo & D. Hawksw., B. implexa (Hoffm.) Brodo & D. Hawksw., B. nadvornikiana (Gyeln.) Brodo & D. Hawksw. The most common species in the valley was B. implexa. Four chemotypes of this lichen were recognized.
Obestatin as contractile mediator of excised frog heart
Authors: Sazdova Iliyana , Ilieva Bilyana , Minkov Ignat , Schubert Rudolf , Gagov Hristo 
Published: July 2009

AbstractThe aim of this study is to investigate the mechanism of positive inotropic effect of obestatin on in vitro heart preparations of Rana ridibunda frog. The application of increasing amounts of obestatin in the concentration range from 1 μmol/l to 1 μmol/l significantly enhances the force of contraction of excised and cannulated frog hearts. This effect was partially reduced in the presence of prazosin (3 μmol/l). Propranolol (30 μmol/l), pertussis toxin (2 ng/ml) and the specific inhibitor of cAMP-dependent protein kinase (PKA) Rp-adenosine 3′,5′-cyclic monophosphothioate triethylamine (30 μmol/l) completely blocked the obestatin-induced increase of the force of frog heart contractions. It is concluded that, via its receptor molecule, obestatin activates neuronal pertussis toxin sensitive G-protein(s) that further enhance the secretion of epinephrine from sympathetic neurons. This epinephrine activates mainly the myocardial β-adrenoreceptors and PKA downstream targets, and is responsible for the observed positive inotropic effect of obestatin. An alternative explanation of our data is that obestatin directly enhances the effect of myocardial β-adrenergic signaling.
Genetic evolution and diversity of common carp Cyprinus carpio L.
Authors: Chistiakov Dimitry , Voronova Natalia 
Published: July 2009

AbstractKnowledge of genetic variation and population structure of existing strains of both farmed and wild common carp Cyprinus carpio L. is absolutely necessary for any efficient fish management and/or conservation program. To assess genetic diversity in common carp populations, a variety of molecular markers were analyzed. Of those, microsatellites and mitochondrial DNA were most frequently used in the analysis of genetic diversity and genome evolution of common carp. Using microsatellites showed that the genome evolution in common carp exhibited two waves of rearrangements: one whole-genome duplication (12–16 million years ago) and a more recent wave of segmental duplications occurring between 2.3 and 6.8 million years ago. The genome duplication event has resulted in tetraploidy since the common carp currently harbors a substantial portion of duplicated loci in its genome and twice the number of chromosomes (n = 100–104) of most other cyprinid fishes. The variation in domesticated carp populations is significantly less than that in wild populations, which probably arises from the loss of variation due to founder effects and genetic drift. Genetic differentiation between the European carp C.c. carpio and Asian carp C.c. haematopterus is clearly evident. In Asia, two carp subspecies, C.c. haematopterus and C.c. varidivlaceus, seem to be also genetically distinct.
Circadian clocks and phosphorylation: Insights from computational modeling
Authors: Leloup Jean-Christophe 
Published: July 2009

AbstractCircadian clocks are based on a molecular mechanism regulated at the transcriptional, translational and post-translational levels. Recent experimental data unravel a complex role of the phosphorylations in these clocks. In mammals, several kinases play differential roles in the regulation of circadian rhythmicity. A dysfunction in the phosphorylation of one clock protein could lead to sleep disorders such as the Familial Advanced Sleep Phase Disorder, FASPS. Moreover, several drugs are targeting kinases of the circadian clocks and can be used in cancer chronotherapy or to treat mood disorders. In Drosophila, recent experimental observations also revealed a complex role of the phosphorylations. Because of its high degree of homology with mammals, the Drosophila system is of particular interest. In the circadian clock of cyanobacteria, an atypical regulatory mechanism is based only on three clock proteins (KaiA, KaiB, KaiC) and ATP and is sufficient to produce robust temperature-compensated circadian oscillations of KaiC phosphorylation. This review will show how computational modeling has become a powerful and useful tool in investigating the regulatory mechanism of circadian clocks, but also how models can give rise to testable predictions or reveal unexpected results.
Resolving group delay of narrowband optical filters from their transmission characteristics
Authors: Śliwczyński Ł. 
Published: July 2009

AbstractIn the paper, the factors affecting the accuracy of calculating the optical filter group delay basing on the measured power transmission characteristic are analyzed. Having the phase characteristic of the filter recovered from its transmission, the group delay is usually calculated via differentiation. The new, direct formula is proposed giving more accurate results when the characteristic of the filter is available in the limited frequency range. Also the limitations arising from the noise of the optical spectrum analyzer are examined.
Determination of optical field generated by a microlens using digital holographic method
Authors: Kozacki T. , Józwik M. , Jóźwicki R. 
Published: July 2009

AbstractIn the paper, application of the digital holographic method for full field characterization of the beam generated by microlenses is considered. For this goal, the laboratory setup was designed based on Mach-Zehnder interferometry with the additional reference channel. The beam generated by a microlens was imaged by an afocal system and intensity distributions or interferograms (holograms) were registered by CCD camera. The digital holography using one image allows us to determine microlens parameters, i.e., focal length, aberrations, and shape. The optimum conditions to determine the surface shape of a microlens using holographic method have been found. We compare obtained results with geometrical and interferometric measurements. We show the advantage of digital holography for a shape microlens determination (improved accuracy), aberrations, and focal length (characterization facility). Through optimum refocusing, the digital holography gives more precise shape. The paper is accompanied with computer simulations and the experimental measurement data for geometrical, interferometric, and holographic methods.
Improvement in dispersion tolerance of high-speed fiber optic transmission link by optimization of laser modulation
Authors: Krehlik P. 
Published: July 2009

AbstractIn this paper, the improvement in dispersion tolerance of high-speed transmission link with directly modulated laser is presented. The method is based on adopting the laser modulation (its amplitude and depth) accordingly to the dispersion of actual link. As it is shown, the tolerance of negative dispersion may be doubled and of positive increased even seven times. The simulations are proved by hardware experiment, in which the extended dispersion tolerance is demonstrated.
Light-controlled helical pitch and dynamic gratings
Authors: Boychuk V. , Gerus I. , Iljin A. , Parka J. 
Published: July 2009

AbstractA chiral nematic liquid crystal (LC) with a photo-sensitive chiral agent is employed for a light-controlled modulation of optical activity and used as a model substance for a dynamic diffraction grating recording. The described liquid crystalline system has shown a strong nonlinear response with effective parameter of cubic nonlinearity being much greater of that characteristic of the orientational nonlinearity of LC. A simple mathematical model of light diffraction on the grating of modulated optical activity was developed. Calculated values of intensities and polarisation states of diffracting beams have shown very good agreement with the experimental data. LC systems with light-controlled chirality could be promising media for nonlinear optical applications or all-optical switching devices.
Consensual Decision-Making Among Epistemic Peers
Authors: Hartmann Stephan , Martini Carlo , Sprenger Jan 
Published: July 2009

ABSTRACTThis paper focuses on the question of how to resolve disagreement and uses the Lehrer-Wagner model as a formal tool for investigating consensual decision-making. The main result consists in a general definition of when agents treat each other as epistemic peers (Kelly 2005; Elga 2007), and a theorem vindicating the “equal weight view” to resolve disagreement among epistemic peers. We apply our findings to an analysis of the impact of social network structures on group deliberation processes, and we demonstrate their stability with the help of numerical simulations.
Deliberative Exchange, Truth, and Cognitive Division of Labour: A Low-Resolution Modeling Approach
Authors: Hegselmann Rainer , Krause Ulrich 
Published: July 2009

ABSTRACTThis paper develops a formal framework to model a process in which the formation of individual opinions is embedded in a deliberative exchange with others. The paper opts for a low-resolution modeling approach and abstracts away from most of the details of the social-epistemic process. Taking a bird's eye view allows us to analyze the chances for the truth to be found and broadly accepted under conditions of cognitive division of labour combined with a social exchange process. Cognitive division of labour means that only some individuals are active truth seekers, possibly with different capacities. Both mathematical tools and computer simulations are used to investigate the model. As an analytical result, the Funnel Theorem states that under rather weak conditions on the social process, a consensus on the truth will be reached if all individuals possess an arbitrarily small capacity to go for the truth. The Leading the pack Theorem states that under certain conditions even a single truth seeker may lead all individuals to the truth. Systematic simulations analyze how close agents can get to the truth depending upon the frequency of truth seekers, their capacities as truth seekers, the position of the truth (more to the extreme or more in the centre of an opinion space), and the willingness to take into account the opinions of others when exchanging and updating opinions.
Extending the Hegselmann–Krause Model III: From Single Beliefs to Complex Belief States
Authors: Riegler Alexander , Douven Igor 
Published: July 2009

ABSTRACTIn recent years, various computational models have been developed for studying the dynamics of belief formation in a population of epistemically interacting agents that try to determine the numerical value of a given parameter. Whereas in those models, agents’ belief states consist of single numerical beliefs, the present paper describes a model that equips agents with richer belief states containing many beliefs that, moreover, are logically interconnected. Correspondingly, the truth the agents are after is a theory (a set of sentences of a given language) rather than a numerical value. The agents epistemically interact with each other and also receive evidence in varying degrees of informativeness about the truth. We use computer simulations to study how fast and accurately such populations as wholes are able to approach the truth under differing combinations of settings of the key parameters of the model, such as the degree of informativeness of the evidence and the weight the agents give to the evidence.
Optimal Publishing Strategies
Authors: Zollman Kevin J. S. 
Published: July 2009

ABSTRACTJournals regulate a significant portion of the communication between scientists. This paper devises an agent-based model of scientific practice and uses it to compare various strategies for selecting publications by journals. Surprisingly, it appears that the best selection method for journals is to publish relatively few papers and to select those papers it publishes at random from the available “above threshold” papers it receives. This strategy is most effective at maintaining an appropriate type of diversity that is needed to solve a particular type of scientific problem. This problem and the limitation of the model is discussed in detail.
Meta-Induction and Social Epistemology: Computer Simulations of Prediction Games
Authors: Schurz Gerhard 
Published: July 2009

ABSTRACTThe justification of induction is of central significance for cross-cultural social epistemology. Different ‘epistemological cultures’ do not only differ in their beliefs, but also in their belief-forming methods and evaluation standards. For an objective comparison of different methods and standards, one needs (meta-)induction over past successes. A notorious obstacle to the problem of justifying induction lies in the fact that the success of object-inductive prediction methods (i.e., methods applied at the level of events) can neither be shown to be universally reliable (Hume's insight) nor to be universally optimal. My proposal towards a solution of the problem of induction ismeta-induction. The meta-inductivist applies the principle of induction to all competing prediction methods that areaccessibleto her. By means of mathematical analysis and computer simulations ofprediction gamesI show that there exist meta-inductive prediction strategies whose success is universally optimal among all accessible prediction strategies, modulo a small short-run loss. The proposed justification of meta-induction is mathematically analytical. It implies, however, an a posteriori justification of object-induction based on the experiences in our world. In the final section I draw conclusions about the significance of meta-induction for the social spread of knowledge and the cultural evolution of cognition, and I relate my results to other simulation results which utilize meta-inductive learning mechanisms.
The Impact of Systemic Lupus Erythematosus on Employment
Authors: CAMPBELL ROBERT , COOPER GLINDA S. , GILKESON GARY S. 
Published: July 2009

Objective.Our primary objective was to examine work status (e.g., job loss, changes in amount worked) and predictors of job loss in patients with systemic lupus erythematosus (SLE).Methods.Recently diagnosed SLE patients were enrolled in the Carolina Lupus Study between 1997 and 1999; an age-, sex-, and state-matched control group selected through driver’s license registries for the 60-county study area was also enrolled. In 2001, a followup study of both groups was conducted (median 4 yrs since diagnosis). Work history data were obtained in an in-person interview at enrollment and a telephone interview at followup.Results.Fifty-one patients (26%) and 26 controls (9%) (p < 0.0001) who were working the year before diagnosis (or for controls, a corresponding reference year) were no longer working at followup; 92% of patients compared with 40% of controls who were no longer working indicated that they had stopped working because of their health (p < 0.0001). College graduates were less likely to quit their jobs due to health compared to non-college graduates (adjusted OR = 0.27, 95% CI 0.09, 0.84). SLE patients with arthritis were 3 times more likely to have left their jobs due to health reasons compared to those who didn’t have arthritis (adjusted OR = 3.3, 95% CI 1.2, 8.8); an association was also seen with pleuritis (adjusted OR 2.3, 95% CI 1.1, 4.6).Conclusion.The burden expressed as work cessation due to health, especially among lesser educated patients and those with arthritis or pleuritis, is significant even early in the disease process.
Proteolytic Activation of the Cytotoxic Phenotype during Human NK Cell Development
Authors: Meade Josephine L. , Wilson Erica B. , Holmes Tim D. , de Wynter Erika A. , Brett Peter , Straszynski Liz , Ballard Paul A. S. , Trapani Joseph A. , McDermott Michael F. , Cook Graham P. 
Published: July 2009

Abstract
NK cells induce apoptosis in target cells via the perforin-mediated delivery of granzyme molecules. Cytotoxic human NK cells can be generated by IL-15-mediated differentiation of CD34+ cells in vitro and these cultures have been used extensively to analyze the development of the NK cell surface phenotype. We have used NK cell differentiation in vitro together with protease-deficient human NK cells to analyze the acquisition of the cytotoxic phenotype. Granzymes are synthesized as inactive zymogens and are proteolytically activated by the cysteine protease cathepsin C. Cathepsin C is also synthesized as a zymogen and activated by proteolysis. We show that human NK cells generated in vitro undergo granule exocytosis and induce the caspase cascade in target cells. IL-15 and stem cell factor (IL-15 plus SCF) induced the expression of the granzyme B and perforin genes and the activation of cathepsin C and granzyme B zymogens. Perforin activation is also mediated by a cysteine protease and IL-15 plus SCF-mediated differentiation was accompanied by perforin processing. However, cathepsin C-deficient human NK cells revealed that perforin processing could occur in the absence of cathepsin C activity. The combination of IL-15 plus SCF is therefore sufficient to coordinate the development of the NK cell surface phenotype with the expression and proteolytic activation of the cytotoxic machinery, reflecting the central role of IL-15 in NK cell development.
Inhibition of ERK MAPK Suppresses IL-23- and IL-1-Driven IL-17 Production and Attenuates Autoimmune Disease
Authors: Brereton Corinna F. , Sutton Caroline E. , Lalor Stephen J. , Lavelle Ed C. , Mills Kingston H. G. 
Published: July 2009

Abstract
IL-17-producing CD4+ T (Th17) cells are pathogenic in many autoimmune diseases. The induction and expansion of Th17 cells is directed by cytokines, including IL-23 and IL-1β, produced by innate immune cells through activation of pathogen recognition receptors. The NF-κB and IFN regulatory factor families of transcriptional factors mediate IL-12 production; however, distinct signaling pathways appear to be required for IL-23 production. In this study, we show that inhibition of ERK MAPK suppressed IL-23 and IL-1β production by dendritic cells stimulated with TLR or dectin-1 agonists but did not affect IL-12p70 production. Furthermore, an ERK inhibitor suppressed the ability of Ag-pulsed TLR-activated dendritic cells to induce Ag-specific Th17 cells in vivo, but interestingly also inhibited the induction of Th1 cells. Treatment with an ERK inhibitor attenuated experimental autoimmune encephalomyelitis (EAE), when administered either at the induction phase of acute EAE or during remission in the relapsing-remitting EAE model. This was associated with significant suppression of autoantigen-specific Th17 and Th1 responses. The suppressive effect of the ERK inhibitor on attenuation of EAE was reversed by administration of IL-1β and IL-23. Our findings suggest that ERK MAPK plays a critical and hitherto undescribed role in activating innate production of IL-23 and IL-1β, which promote pathogenic T cell responses, and therefore represents an important target for therapeutic intervention against autoimmune diseases.
Cutting Edge: Regulatory T Cells Directly Suppress B Cells in Systemic Lupus Erythematosus
Authors: Iikuni Noriko , Lourenço Elaine V. , Hahn Bevra H. , La Cava Antonio 
Published: July 2009

Abstract
In systemic lupus erythematosus (SLE), adaptive CD4+CD25+Foxp3+ regulatory T cells (Tregs) suppress Th cells that help autoantibody (autoAb)-producing B cells. It is not known whether naturally occurring Tregs can directly suppress B cells in SLE without an intermediate suppression of Th cells. This aspect is important for its implications in the natural course of SLE, because most if not all of the clinical and pathologic effects in SLE are associated with a dysregulated production of autoAbs. In this study, we show that natural Tregs can inhibit B cell activity in vitro and in vivo in SLE through cell contact-mediated mechanisms that directly suppress autoAb-producing B cells, including those B cells that increase numerically during active disease. These results indicate that one way by which natural Tregs attempt to limit humoral autoimmunity in SLE is by directly targeting autoreactive B cells.