179 research outputs found

    An Iterative Quality-Based Localization Algorithm for Ad Hoc Networks

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    An iterative quality-based algorithm for location discovery is presented which can be used in wireless ad hoc sensor networks. The algorithm will take the reliability of measurements into account and will produce a reliability index for every estimated location using a statistical approach. The algorithm can also work in a hybrid network with different kinds of distance measuring techniques. It will use the reliability of each of these methods in the final result. Satisfactory results can be achieved with this approach

    Modeling charity donations: target selection, response time and gift size

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    Charitable organizations often consider direct mailings to raise donations. Obviously, it is important for a charity to make a profitable selection from available mailing lists, which can be its own list or a list obtained elsewhere. For this purpose, a charitable organization usually has to address the following four questions: 1. Who should we send a mailing? 2. Who is likely to respond to that mailing? 3. How much time will it take for such an individual to respond? 4. How much money will this individual donate? Several techniques for addressing one or more of these questions have been suggested in the literature. For example, Bult and Wansbeek (1995) develop a model that addresses question 2. Otter et al. (1997) develop a model that jointly considers questions 2 and 4. In practice one often relies on techniques such as RFM-based decision rules (Bauer 1988) in order to answer question 1. In this paper we develop a model which enables a charitable organization to make an optimal selection from its own mailing list, while simultaneously considering the four questions above. Hence, our model consists of four components with a possible non-zero correlation structure. The explanatory variables in each of these components are RFM-type variables, where these are allowed to have different effects on the various variables to be explained. In particular, we show that the first component is essential when a target selection model is applied on a database. Neglecting this component can generate a substantial bias in the results of subsequent analysis. The various model parameters are estimated by maximum likelihood. We illustrate our model using a random drawing of about 5,300 individuals from the database of a large Dutch charitable organization. Our empirical results indicate the relevance of the non-zero correlation across the model components, and the relevance of taking account of the target selection part. We find some RFM variables to have effects with opposite signs on the probability to respond, the time for response and the donation. It is found that the most profitable individuals are not the ones who have maximum scores on the RFM variables. We conclude with a discussion of various further research topics

    Validation of a simplified intravascular ultrasound core lab analysis method in stented coronary arteries

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    OBJECTIVES: To validate a simplified core laboratory intravascular ultrasound (IVUS) analysis method based on frames with visually determined minimal lumen areas (MLAs) as compared with a comprehensive (per frame) analysis method. BACKGROUND: IVUS‐guided percutaneous coronary intervention has proven to be superior to angiography‐guided stenting. In clinical practice, cross‐sections with visually determined MLA are measured to determine lesion severity or minimal stent area (MSA), however, its accuracy has not been compared with a comprehensive per frame analysis method. METHODS: A total of 50 stented coronary segments of anonymized core lab datasets were analyzed using a comprehensive analysis method and reanalyzed by two core lab analysts using the simplified method including a maximum of seven frames to be analyzed (the visually determined MSA, the first and last frame, and the MLA of each reference segment). The main parameters of interest were MSA, MLA in the reference segments, and plaque burden. RESULTS: The simplified method showed moderate agreement for measurement of the proximal MLA (7.51 ± 2.52 vs. 6.32 ± 1.88 mm(2), intraclass correlation coefficient [ICC] = 0.73), good agreement for the distal MLA (5.41 ± 1.85 vs. 5.11 ± 1.38 mm(2), ICC = 0.84) and plaque burden proximal (0.49 ± 0.12 vs. 0.50 ± 0.11, ICC = 0.88), and excellent agreement for the MSA (5.35 ± 1.05 vs. 5.32 ± 0.99 mm(2), ICC = 0.94) and plaque burden distal (0.47 ± 0.14 vs. 0.47 ± 0.12, ICC = 0.92), when compared with the comprehensive analysis method. Inter‐ and intraobserver analysis revealed good‐to‐excellent agreement for all parameters. CONCLUSIONS: Measuring poststenting IVUS cross‐sections with visually determined MLAs by experienced core lab analysts is an accurate and reproducible method to identify MLAs

    Paradoxically, Most Flexible Ligand Binds Most Entropy-Favored: Intriguing Impact of Ligand Flexibility and Solvation on Drug-Kinase Binding

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    Biophysical parameters can accelerate drug development; e.g., rigid ligands may reduce entropic penalty and improve binding affinity. We studied systematically the impact of ligand rigidification on thermodynamics using a series of fasudil derivatives inhibiting protein kinase A by crystallography, isothermal titration calorimetry, nuclear magnetic resonance, and molecular dynamics simulations. The ligands varied in their internal degrees of freedom but conserve the number of heteroatoms. Counterintuitively, the most flexible ligand displays the entropically most favored binding. As experiment shows, this cannot be explained by higher residual flexibility of ligand, protein, or formed complex nor by a deviating or increased release of water molecules upon complex formation. NMR and crystal structures show no differences in flexibility and water release, although strong ligand-induced adaptations are observed. Instead, the flexible ligand entraps more efficiently water molecules in solution <i>prior</i> to protein binding, and by release of these waters, the favored entropic binding is observed

    Relationships between renal cytoplasmic and nuclear aldosterone-receptors

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    Relationships between renal cytoplasmic and nuclear aldosteronereceptors.Three 3H-aldosterone receptor complexes have been recovered from rat kidneys: 1) cytosol (high speed supernatants), 2) Tris-soluble nuclear (obtained by an osmotic shock procedure), and 3) chromatin-bound (prepared by extracting post-shock nuclei with 0.4 M KCl).Glycerol density gradient analyses of cytosol labelled in vivo or in vitro with 3H-aldosterone yielded two specific peaks -4.5S and 8.5S.These peaks were sensitive to salt concentration; 0.4 M KCl shifted the 8.5S to 4.5S and the addition of Ca++ (6 mM) resulted in a further shift to 3.5S.The Tris-soluble nuclear species sedimented at 3S and the chromatin-bound species at 4S.The time-course of generation of the 3H-aldosterone-labelled cytosol and nuclear receptor species was studied in vivo and in vitro by tissue slice and reconstitution methods.The results obtained are consistent with a three-step mechanism: cytosol (8.5S or 4.5S)→ Tris-soluble nuclear (3S)→ chromatin-bound (4S).Alternatively, the 3S and 4S complexes may be attached to independent nuclear sites.The formation of the chromatin-bound species was temperature sensitive and failed to form at 0°C.Pre-treatment with DNase but not RNase impaired the generation of both the Tris-soluble nuclear and chromatin-bound species.These results imply a close association between nuclear aldosterone-receptor complexes and intact DNA

    Social networks and political participation in a Sicilian community context

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    AbstractThis study shows the linkage between political and social participation, underlining the relevance of the motivational sphere. The aim is to evaluate politically relevant social capital by adopting a relational perspective and ego-network measures, so that we can understand the interdependence between cognitive maps, motivational factors and relational dimension, both in qualitative and quantitative dimensions

    Interplay of superexchange and orbital degeneracy in Cr-doped LaMnO3

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    We report on structural, magnetic and Electron Spin Resonance (ESR) investigations in the manganite system LaMn_{1-x}Cr_{x}O_{3} (x<=0.5). Upon Cr-doping we observe a reduction of the Jahn-Teller distortion yielding less distorted orthorhombic structures. A transition from the Jahn-Teller distorted O' to the pseudocubic O phase occurs between 0.3<x<0.4. A clear connection between this transition and the doping dependence of the magnetic and ESR properties has been observed. The effective moments determined by ESR seem reduced with respect to the spin-only value of both Mn^{3+} and Cr^{3+} ions

    Comparative assessment of “plaque/media” change on three modalities of IVUS immediately after implantation of either everolimus-eluting bioresorbable vascular scaffold or everolimus-eluting metallic stent in Absorb II study

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    The purpose of the study to assess the comparability of immediate changes in plaque/media volume (PV) on three modalities of intravascular ultrasound (IVUS) after implantation of either bioresorbable vascular scaffold (BVS) or everolimus-eluting metallic stent (EES) in Absorb II Study. The two devices have different device volume and ultrasound backscattering that may interfere with the "plaque/media" assessed by three modalities on IVUS: grayscale, backscattering of radiofrequency and brightness function. In a multicenter randomized controlled trial, 501 patients with stable or unstable angina underwent documentary IVUS pre- and post- implantation. The change in plaque/media volume (PV) was categorized into three groups according to the relative PV change in device segment: PV "increased" >+5% (PVI), PV unchanged ±5% (PVU), and PV decreased <-5% (PVD). The change in PV was re-evaluated three times: after subtraction of theoretical device volume, after analysis of echogenicity based on brightness function. In 449 patients, 483 lesions were analyzed pre- and post-implantation. "PVI" was more frequently observed in BVS (53.8%) than EES group (39.4%), p = 0.006. After subtraction of the theoretical device volume, the frequency of "PVI" decreased in both BVS (36.2%) and EES (32.1%) groups and became comparable (p = 0.581). In addition, the percentage of "PVI" was further reduced in both device groups after correction for either radiofrequency backscattering (BVS 34.4% vs. EES 22.6%) or echogenicity (BVS 25.2% vs. EES 9.7%). PV change in device segment was differently affected by BVS and EES devices implantation due to their differences in device volume and ultrasound backscattering. It implies that the lumen volume was also artifactually affected by the type of device implanted. Comparative IVUS assessment of lumen and plaque/media volume changes following implantation of BVS and EES requires specific methodological adjustmen

    Technology and Society in Equilibrium:

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    This sector portrait of the design engineering sciences describes the common denominator of the various design disciplines in the Netherlands. In a future sector plan, the above investment areas will be further explored and purposefully developed. The implementation of technological innovations aligned to societal issues encompasses a design challenge. This increasingly demands science-based design methodologies. The broad Dutch design landscape can fulfil the role of connector well in this regard. In order to optimally strengthen this bridging function, three areas for further investment have been identified: Research More research and research funding are needed to meet the design challenges posed by Dutch societal missions, as well as for the further development of Key Enabling Methodologies (KEMs) as the basis for effective design. Educational Capacity Expanded teaching capacity and further development of design-driven didactics are needed to meet the growing demand for designers, This demand stems from the emerging need for design approaches in new research programmes within Horizon Europe and the Dutch Research Council (NWO). Access to Technology Continuous access to the rapidly evolving technological disciplines must be guaranteed for professionals who can both understand the technology and meet the investigative design challenge
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