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Second Level (second + level)
Selected AbstractsThree-Dimensional Optimization of Urban Drainage SystemsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2000A. Freire Diogo A global mathematical model for simultaneously obtaining the optimal layout and design of urban drainage systems for foul sewage and stormwater is presented. The model can handle every kind of network, including parallel storm and foul sewers. It selects the optimal location for pumping systems and outfalls or wastewater treatment plants (defining the natural and artificial drainage basins), and it allows the presence of special structures and existing subsystems for optimal remodeling or expansion. It is possible to identify two basic optimization levels: in the first level, the generation and transformation of general layouts (consisting of forests of trees) until a convergence criterion is reached, and in the second level, the design and evaluation of each forest. The global strategy adopted combines and develops a sequence of optimal design and plan layout subproblems. Dynamic programming is used as a very powerful technique, alongside simulated annealing and genetic algorithms, in this discrete combinatorial optimization problem of huge dimension. [source] Adults with self-reported learning disabilities in Slovenia: Findings from the international adult literacy survey on the incidence and correlates of learning disabilities in SloveniaDYSLEXIA, Issue 4 2003Lidija Magajna This study of adults with self-reported learning disabilities (SRLD) in Slovenia is part of a larger secondary analysis of the data from the International Literacy Survey project (IALS). The purpose of the study was to examine the characteristics of 79 (2.68%) individuals who reported experiencing learning disabilities and compare them to the general population on a variety of indicators of educational background, employment status, and reading and writing activities at work and at home. The proficiency scores of the SRLD individuals were lower in all three literacy domains (prose, document and quantitative literacy). In prose literacy 77.9% of SRLD adults performed at Level 1 and only 7.8% reached the level necessary for a modern technological society. Experiencing learning disabilities was not related to gender or age, however, results showed significant differences between the levels achieved by older and younger people with SRLD. In SRLD groups aged 40 years and above, no one achieved more than the second level of literacy in any domain. Learning disabilities were reported more frequently in rural areas. SRLD groups achieve significantly lower educational attainment, and lower employment status, with a preference for manual labour or craft. These findings are of critical importance. SRLD people report that poorer literacy skills are an obstacle to their progression in employment. In the Slovene sample, the SRLD group stands out for low scores in quantitative literacy. Results show that they are less active, pick up information only auditorily or in short written form. They need more frequent help from relatives in literacy activities. Interpretation of the IALS data on SRLD presents many problems. These include amongst others, problems in terminology, different background factors, and the validity of self-report measures. However, the study also raises many interesting challenges for future research and policy. Increasing the availability of support, assistance and counselling for adolescents and adults with learning disabilities remains a very important goal for dyslexia and LD policies in Slovenia. Copyright © 2003 John Wiley & Sons, Ltd. [source] A 3-D dielectrophoretic filter chipELECTROPHORESIS, Issue 7 2007Ciprian Iliescu Dr. Abstract The paper presents a 3-D filter chip employing both mechanical and dielectrophoretic (DEP) filtration, and its corresponding microfabrication techniques. The device structure is similar to a classical capacitor: two planar electrodes, made from a stainless steel mesh, and bonded on both sides of a glass frame filled with round silica beads. The solution with the suspension of particles flows through both the mesh-electrodes and silica beads filter. The top stainless steel mesh (with openings of 60,,m and wires of 30,,m-thickness) provides the first stage of filtration based on mechanical trapping. A second level of filtration is based on DEP by using the nonuniformities of the electric field generated in the capacitor due to the nonuniformities of the dielectric medium. The filter can work also with DC and AC electric fields. The device was tested with yeast cells (Saccharomyces cerevisae) and achieved a maximal trapping efficiency of 75% at an applied AC voltage of 200,V and a flow rate of 0.1,mL/min, from an initial concentration of cells of 5×105 cells/mL. When the applied frequency was varieted in the range between 20 and 200,kHz, a minimal value of capture efficiency (3%) was notticed at 50,kHz, when yeast cells exhibit negative DEP and the cells are repelled in the space between the beads. [source] Integrated regulation in response to aromatic compounds: from signal sensing to attractive behaviourENVIRONMENTAL MICROBIOLOGY, Issue 12 2003Victoria Shingler Summary Deciphering the complex interconnecting bacterial responses to the presence of aromatic compounds is required to gain an integrated understanding of how aromatic catabolic processes function in relation to their genome and environmental context. In addition to the properties of the catabolic enzymes themselves, regulatory responses on at least three different levels are important. At a primary level, aromatic compounds control the activity of specific members of many families of transcriptional regulators to direct the expression of the specialized enzymes for their own catabolism. At a second level, dominant global regulation in response to environmental and physiological cues is incorporated to subvert and couple transcription levels to the energy status of the bacteria. Mediators of these global regulatory responses include the alarmone (p)ppGpp, the DNA-bending protein IHF and less well-defined systems that probably sense the energy status through the activity of the electron transport chain. At a third level, aromatic compounds can also impact on catabolic performance by provoking behavioural responses that allow the bacteria to seek out aromatic growth substrates in their environment. [source] Bayesian hierarchical generalized linear models for a geographical subset of recovery dataENVIRONMETRICS, Issue 2 2002Daniela Cocchi Abstract The aim of this work is to check whether modifications in the length of the hunting seasons had an effect on the chance of reproduction of different species of ringed birds. We start from a national data set of ringing-recovered data on three species of game birds. Only data on birds recovered as juveniles are used. Data on recoveries are organized in a 4-way contingency table. Several generalized linear models are proposed for the counts of recovered birds. Bayesian hierarchical modeling is particularly suitable for this kind of data, for which an over-dispersion parameter can be introduced at the second level of the hierarchy. Maximum Likelihood and Bayesian solutions are computed for the different models: the Bayesian framework, in particular under an individual modeling of over-dispersion, exhibits the best fit in terms of Bayesian p -value. The results show that the modification in the length of the hunting seasons does not produce equal benefits for the three species considered. Copyright © 2002 John Wiley & Sons, Ltd. [source] Mechanisms of time-based figure,ground segregationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2003Farid I. Kandil Abstract Figure,ground segregation can rely on purely temporal information, that is, on short temporal delays between positional changes of elements in figure and ground (Kandil, F.I. & Fahle, M. (2001) Eur. J. Neurosci., 13, 2004,2008). Here, we investigate the underlying mechanisms by measuring temporal segregation thresholds for various kinds of motion cues. Segregation can rely on monocular first-order motion (based on luminance modulation) and second-order motion cues (contrast modulation) with a high temporal resolution of ,,20 ms. The mechanism can also use isoluminant motion with a reduced temporal resolution of 60 ms. Figure,ground segregation can be achieved even at presentation frequencies too high for human subjects to inspect successive frames individually. In contrast, when stimuli are presented dichoptically, i.e. separately to both eyes, subjects are unable to perceive any segregation, irrespective of temporal frequency. We propose that segregation in these displays is detected by a mechanism consisting of at least two stages. On the first level, standard motion or flicker detectors signal local positional changes (flips). On the second level, a segregation mechanism combines the local activities of the low-level detectors with high temporal precision. Our findings suggest that the segregation mechanism can rely on monocular detectors but not on binocular mechanisms. Moreover, the results oppose the idea that segregation in these displays is achieved by motion detectors of a higher order (motion-from-motion), but favour mechanisms sensitive to short temporal delays even without activation of higher-order motion detectors. [source] Detailed examination of lymph nodes improves prognostication in colorectal cancerINTERNATIONAL JOURNAL OF CANCER, Issue 11 2010Fania S. Doekhie Abstract Up to 30% of stage II patients with curatively resected colorectal cancer (CRC) will develop disease recurrence. We evaluated whether examination of lymph nodes by multilevel sectioning and immunohistochemical staining can improve prognostication. Lymph nodes (n = 780) from 36 CRC patients who had developed disease recurrence (cases) and 72 patients who showed no recurrence of disease for at least 5 years (controls) were analyzed. Sections of 4 levels at 200-,m interval were immunohistochemically stained for cytokeratin expression. The first level was analyzed by conventional and automated microscopy, and the 3 following levels were analyzed by automated microscopy for the presence of tumor cells. Overall, cases showed more micrometastases (3 patients) than controls (1 patient). Analysis of a second level led to the additional detection of 1 patient with micrometastases (case) and 1 patient with macrometastasis (case). Examining more levels only led to additional isolated tumor cells, which were equally divided between cases and controls. Likewise, automated microscopy resulted only in detection of additional isolated tumor cells when compared with conventional microscopy. In multivariate analysis, micrometastases [odds ratio (OR) 26.3, 95% confidence interval (CI) 1.9,364.8, p = 0.015], T4 stage (OR 4.8, 95% CI 1.4,16.7, p = 0.013) and number of lymph nodes (OR 0.9, 95% CI 0.8,1.0, p = 0.028) were independent predictors for disease recurrence. Lymph node analysis of 2 levels and immunohistochemical staining add to the detection of macrometastases and micrometastases in CRC. Micrometastases were found to be an independent predictor of disease recurrence. Isolated tumor cells were of no prognostic significance. [source] Regional Inequalities in Consumption Patterns: A Multilevel Approach to the Case of ItalyINTERNATIONAL STATISTICAL REVIEW, Issue 1 2007Filippa Bono Summary The main aim of this paper is to evaluate the disparities in the Italian regions on the demand side. In more detail, an attempt will be made to find if the consumption behaviour of Italian households is different in the regions. With this in mind, Istat's 2000 Italian Family Budget data set was analysed. The data in question, which were collected through a two-stage sample over Italy's 20 regions, contains information regarding the expenses of approximately 23,000 households. In this analysis, both households and regions are considered as units: households are nested in the regions so that the basic data structure is hierarchical. In order to take this hierarchical structure into account, a multilevel model was used, making it possible for parameters to vary randomly from region to region. The model in question also made it possible to consider heterogeneity across different groups (regions), such as stochastic variation. First, regional inequalities were tested using a simple model in which households constituted the first level of analysis and were grouped according to their region (the second level). As a second step, and in order to investigate the interaction between geographical context and income distribution, another model was used. This was cross-classified by income and regions. The most relevant results showed that there is wide fragmentation of consumption behaviour and, at the same time, various differentiated types of behaviour in the regions under analysis. These territorial differentials become clear from income class and items of consumption. Resumé L'objet du travail est l'analyse des différences, entre les régions italiennes, des comportements des consommateurs. Le traitement statistique des données individuelles est originale car il est conduit par un modèle ,multilevel'. Le modèle multilevel tient compte de la structure hiérarchique de données et permet au paramètres estimée de varier par hasard. En outre, ce modèle permet que l'hétérogénéité entre le différent groupes de familles (les unités statistiques) peut varier par hasard entre le régions. Pour l'analyse des différences régionales modèle ,multilevel nous avons estimée un premier modèle avec les familles au premier dégrée hiérarchique et les régions au second dégrée. Car le facteur géographique interagit avec la distribution du revenue dans chaque région nous avons estimée un autre modèle cross-classifiée par lequel le familles sont groupées par le revenue. [source] Setting the agenda of attributes in the 1996 Spanish general electionJOURNAL OF COMMUNICATION, Issue 2 2000M McCombes We advance the central proposition of agenda-setting theory - that elements prominent in the mass media's picture of the world influence the salience of those elements in the audience's picture - through the explication of a second level of agenda setting: attribute agenda setting. This preliminary research on candidate images during the 1996 Spanish general election simultaneously examined 2 attribute dimensions - substantive and affective descriptions - to test the hypothesis that media attribute agendas influence the voters' attribute agenda. Empirically, a high degree of correspondence was found between the attribute agendas of 7 different mass media and the voters' attribute agenda for each of the 3 candidates. The median correlation from these 21 tests of the hypothesis is +.72. Sixth-order partial correlations in which the influence of the other 6 mass media are removed from the correlation between a medium's agenda and the voters' agenda for a particular candidate have a median value of +.73. Additional analyses of the attribute agendas of each medium's primary audience in comparison with its principal competitor also yielded evidence of second-level agenda setting. Future research should pursue complex longitudinal designs tracing the impact of media content on voters' images at both the aggregate and individual levels as part of the continuing scholarly dialogue on competing approaches to framing research and attribute agenda setting. [source] Importance of interpolation when constructing double-bootstrap confidence intervalsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 2 2000Peter Hall We show that, in the context of double-bootstrap confidence intervals, linear interpolation at the second level of the double bootstrap can reduce the simulation error component of coverage error by an order of magnitude. Intervals that are indistinguishable in terms of coverage error with theoretical, infinite simulation, double-bootstrap confidence intervals may be obtained at substantially less computational expense than by using the standard Monte Carlo approximation method. The intervals retain the simplicity of uniform bootstrap sampling and require no special analysis or computational techniques. Interpolation at the first level of the double bootstrap is shown to have a relatively minor effect on the simulation error. [source] Bayesian geoadditive sample selection modelsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 3 2010Manuel Wiesenfarth Summary., Sample selection models attempt to correct for non-randomly selected data in a two-model hierarchy where, on the first level, a binary selection equation determines whether a particular observation will be available for the second level, i.e. in the outcome equation. Ignoring the non-random selection mechanism that is induced by the selection equation may result in biased estimation of the coefficients in the outcome equation. In the application that motivated this research, we analyse relief supply in earthquake-affected communities in Pakistan, where the decision to deliver goods represents the dependent variable in the selection equation whereas factors that determine the amount of goods supplied are analysed in the outcome equation. In this application, the inclusion of spatial effects is necessary since the available covariate information on the community level is rather scarce. Moreover, the high temporal dynamics underlying the immediate delivery of relief supply after a natural disaster calls for non-linear, time varying effects. We propose a geoadditive sample selection model that allows us to address these issues in a general Bayesian framework with inference being based on Markov chain Monte Carlo simulation techniques. The model proposed is studied in simulations and applied to the relief supply data from Pakistan. [source] A Bayesian hierarchical approach to ensemble weather forecastingJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 3 2010A. F. Di Narzo Summary., In meteorology, the traditional approach to forecasting employs deterministic models mimicking atmospheric dynamics. Forecast uncertainty due to partial knowledge of the initial conditions is tackled by ensemble predictions systems. Probabilistic forecasting is a relatively new approach which may properly account for all sources of uncertainty. We propose a hierarchical Bayesian model which develops this idea and makes it possible to deal with ensemble predictions systems with non-identifiable members by using a suitable definition of the second level of the model. An application to Italian small-scale temperature data is shown. [source] A hierarchical modelling approach to analysing longitudinal data with drop-out and non-compliance, with application to an equivalence trial in paediatric acquired immune deficiency syndromeJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 1 2002Joseph W Hogan Longitudinal clinical trials with long follow-up periods almost invariably suffer from a loss to follow-up and non-compliance with the assigned therapy. An example is protocol 128 of the AIDS Clinical Trials Group, a 5-year equivalency trial comparing reduced dose zidovudine with the standard dose for treatment of paediatric acquired immune deficiency syndrome patients. This study compared responses to treatment by using both clinical and cognitive outcomes. The cognitive outcomes are of particular interest because the effects of human immunodeficiency virus infection of the central nervous system can be more acute in children than in adults. We formulate and apply a Bayesian hierarchical model to estimate both the intent-to-treat effect and the average causal effect of reducing the prescribed dose of zidovudine by 50%. The intent-to-treat effect quantifies the causal effect of assigning the lower dose, whereas the average causal effect represents the causal effect of actually taking the lower dose. We adopt a potential outcomes framework where, for each individual, we assume the existence of a different potential outcomes process at each level of time spent on treatment. The joint distribution of the potential outcomes and the time spent on assigned treatment is formulated using a hierarchical model: the potential outcomes distribution is given at the first level, and dependence between the outcomes and time on treatment is specified at the second level by linking the time on treatment to subject-specific effects that characterize the potential outcomes processes. Several distributional and structural assumptions are used to identify the model from observed data, and these are described in detail. A detailed analysis of AIDS Clinical Trials Group protocol 128 is given; inference about both the intent-to-treat effect and average causal effect indicate a high probability of dose equivalence with respect to cognitive functioning. [source] A systematic review of evaluation in formal continuing medical educationTHE JOURNAL OF CONTINUING EDUCATION IN THE HEALTH PROFESSIONS, Issue 1 2007Jing Tian MD Abstract Introduction: Physicians spend a considerable amount of time in Continuing Medical Education (CME) to maintain their medical licenses. CME evaluation studies vary greatly in evaluation methods, levels of evaluation, and length of follow-up. Standards for CME evaluation are needed to enable comparison among different studies and to detect factors influencing CME evaluation. Methods: A review of the CME evaluation literature was conducted on primary research studies published from January 2000 to January 2006. Studies assessing only satisfaction with CME were excluded, as were studies where fewer than 50% of the participants were practicing physicians. Thirty-two studies were included in the analyses. Determinations were made about evaluation methods, outcome measures, and follow-up assessment. Results: Only 2 of 32 reviewed studies addressed all evaluation levels: physician changes in knowledge and attitudes (level 2), practices (level 3), and improved patient health status (level 4). None of the studies using self-developed instruments (n = 10) provided reliability and validity information. Only 6 studies used validated scales. Twenty studies had a follow-up period of 6 months or less, and 11 had a follow-up period between 1 and 2 years. Discussion: A gold standard for evaluating the effectiveness of CME would include assessment of all 4 levels of evaluation. A valid, reliable, and adaptable CME evaluation questionnaire addressing variables in the second level is needed to allow comparison of effectiveness across CME interventions. A minimum 1-year postintervention follow-up period may also be indicated to investigate the sustainability of intervention outcomes. [source] Automated assignment of graph-set descriptors for crystallographically symmetric moleculesACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2000W. D. Samuel Motherwell Algorithms for the automatic assignment of graph-set notation for intermolecular networks have been extended to molecules having internal crystallographic symmetry, for patterns up to the second level. This provides a means of achieving systematic and consistent assignments for networks containing symmetric molecules. These methodologies have been implemented in the program RPLUTO. Examples are given of the application of the method to a number of molecules with hydrogen-bonded and other intermolecular networks, illustrating the diversity of the patterns that occur. [source] Functional Hierarchical Models for Identifying Genes with Different Time-Course Expression ProfilesBIOMETRICS, Issue 2 2006F. Hong Summary Time-course studies of gene expression are essential in biomedical research to understand biological phenomena that evolve in a temporal fashion. We introduce a functional hierarchical model for detecting temporally differentially expressed (TDE) genes between two experimental conditions for cross-sectional designs, where the gene expression profiles are treated as functional data and modeled by basis function expansions. A Monte Carlo EM algorithm was developed for estimating both the gene-specific parameters and the hyperparameters in the second level of modeling. We use a direct posterior probability approach to bound the rate of false discovery at a pre-specified level and evaluate the methods by simulations and application to microarray time-course gene expression data on Caenorhabditis elegans developmental processes. Simulation results suggested that the procedure performs better than the two-way ANOVA in identifying TDE genes, resulting in both higher sensitivity and specificity. Genes identified from the C. elegans developmental data set show clear patterns of changes between the two experimental conditions. [source] Dynamic Capabilities: An Exploration of How Firms Renew their Resource BaseBRITISH JOURNAL OF MANAGEMENT, Issue 2009Véronique Ambrosini The aim of this paper is to extend the concept of dynamic capabilities. Building on prior research, we suggest that there are three levels of dynamic capabilities which are related to managers' perceptions of environmental dynamism. At the first level we find incremental dynamic capabilities: those capabilities concerned with the continuous improvement of the firm's resource base. At the second level are renewing dynamic capabilities, those that refresh, adapt and augment the resource base. These two levels are usually conceived as one and represent what the literature refers to as dynamic capabilities. At the third level are regenerative dynamic capabilities, which impact, not on the firm's resource base, but on its current set of dynamic capabilities, i.e. these change the way the firm changes its resource base. We explore the three levels using illustrative examples and conclude that regenerative dynamic capabilities may either come from inside the firm or enter the firm from outside, via changes in leadership or the intervention of external change agents. [source] Biochemical changes in selenite cataract model measured by high-resolution MAS 1H NMR spectroscopyACTA OPHTHALMOLOGICA, Issue 5 2006Miroslav Fris Abstract. Purpose:, To correlate certain levels of lens opacification with high-resolution magic-angle spinning proton nuclear magnetic resonance (HR-MAS 1H NMR) spectroscopy analysis of the biochemical changes in rat lenses in a selenite cataract model. Methods:, Selenite cataract was induced by injecting 13-day-old Sprague-Dawley rat pups with a single subcutaneous dose of sodium selenite (3.28 mg/kg in 0.9% sodium chloride solution). Lens opacification was observed using a photographic slit-lamp microscope at selected time-points 3, 6 and 9 days after selenite injection and was then graded (levels 0, 1 and 2). The animals were killed after the slit-lamp microscopy, lenses were removed and HR-MAS 1H NMR spectra from intact lenses were obtained. Relative changes in metabolite concentrations were determined after comparison with matched lenses from untreated animals. Results:, Photographic slit-lamp microscopy revealed different stages of cataract in all animals treated with selenite. In the high quality HR-MAS 1H NMR spectra of the lenses, more than 30 different metabolites were identified in each lens. With the exception of taurine, the concentrations of all amino acids showed a significant increase (p < 0.05) in the second level of cataract. By contrast, glutathione (GSH), succinate and phosphocholine concentrations were significantly reduced. Conclusions:, For the first time, this study demonstrates the potential to correlate the level of lens opacification with the biochemical changes obtained with HR-MAS 1H NMR spectroscopy analysis in a selenite cataract model. [source] | ||||||||||||||||