Smaller Discrepancy Research Articles

Impact of Preoperative Planning Using Virtual Segmental Volumetry on Liver Resection for Hepatocellular Carcinoma

Accurate assessment of resection volume and vascular anatomy is mandatory in preoperative planning for safe and curative hepatectomy to treat cancer. Accordingly, we examined feasibility and accuracy of a preoperative three-dimensional (3D) computed tomography (CT) scan based simulation in patients with impaired liver function undergoing hepatectomy for hepatocellular carcinoma (HCC). Hepatectomy simulation software was programmed to reconstruct detailed 3D vascular structure and calculate liver volume based on hepatic circulation. In 113 patients with HCC, liver resection volume was estimated preoperatively by both simulation and conventional planimetry. For validation, predicted resection volumes were compared with actual resected specimen weights. The resection margin as estimated by the simulation was compared with the margin in the specimen. Simulation showed higher correlation and smaller discrepancy (r = 0.96; 9.3 ml) between predicted and actual liver resection volume than conventional planimetry (r = 0.74; 174 ml). Simulation showed correlation (p < 0.01) between estimated and actual segmental volume, which was not measurable by planimetry. Simulation showed a correlation (r = 0.84) between predicted and actual margin, with a difference of 1.6 mm. Hepatectomy simulation in 3D predicted segmental liver volume and the resection margin accurately. This virtual method should contribute to preoperative planning to achieve safe, curative resection in HCC patients, whose hepatic function is compromised.

Ion pairing in aqueous calcium chloride solution: Molecular dynamics simulation and diffraction studies

X-ray and neutron diffraction and molecular dynamics simulation studies were performed on 2.5 and 4.0 M aqueous solutions of calcium chloride. The aim of the work, beyond the determination of the solution structure, was to discuss the capability of each method to detect ion pair formation. It has been found that the diffraction methods are performing very well in the determination of Ca 2+–O distances: the obtained values fell in the range 2.43–2.46 Å. Further on, by applying the X-ray diffraction method ion pairs could be observed in the case of higher concentrated solution, but for neutron diffraction study, the most adequate isotope substitution method has to be chosen with care in order to be able to describe ion pairs in solution. The results of diffraction studies were compared to molecular dynamics simulation results; the latter ones were found to be in general accordance with the experimental findings. The smaller discrepancies between the simulation and the experimental results are coming from small differences in the ion–water and ion–ion distances, and they may be due to the potential model applied in the simulation and to the experimental uncertainties.

The second EURADOS intercomparison of national network systems used to provide early warning of a nuclear accident

In 1999 and 2002, the EURADOS Working Group on Environmental Monitoring organised two European intercomparison exercises of national network systems used to provide early warning in case of a nuclear accident. In total, 12 European countries, represented by more than 40 scientists, participated in these two intercomparisons with more than 35 different dose rate detectors. In addition, an in situ gamma spectrometry intercomparison was performed by a group of European scientists during the 2002 exercise. Results of these spectrometry measurements will be reported elsewhere. This report summarises the results of the second intercomparison, performed in 2002, at the environmental dosimetry facilities of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. The unique combination of the ultra-low background Underground Laboratory (UDO) and two free-field sites (a floating platform on a lake showing an almost pure cosmic radiation field and a free-field gamma ray irradiation facility) provide the particular opportunity to precisely quantify the inherent background of the detectors and to calibrate them almost free of any background and traceable to PTB's primary standards. In addition, the intercomparison comprised investigations on the energy and dose rate dependence of the detectors' response to gamma radiation as well as on the response to cosmic radiation. Finally, the sensitivity of the detector systems to small dose rate variations, similar to that caused by a passing overhead radioactive plume, was studied under realistic free-field conditions. Following the Council Directive 96/29/EURATOM, the participants of the 2002 intercomparison were asked to report their results in terms of the operational quantity ambient dose equivalent, H(*)(10). Although the verification of the individual calibrations showed smaller discrepancies than those in the 1999 intercomparison, in a few cases, these discrepancies would be still unacceptably high in the case of a real emergency situation as demonstrated by the plume results. This shows the clear need for further efforts towards a European harmonisation in environmental dosimetry. For this purpose, a further intercomparison shall be held at the PTB in 2006, especially with the participation of new members of the European Union.

New space-averaging procedure for inhomogeneous flow fields using balance equation formulations

This paper features the possibility of averaging space-dependent flow fields using a coupling factor that links the equations of momentum and energy. The scheme is applied to the mean velocity, which is derived straightforwardly through the continuity equation. It creates a small imbalance, which can be eliminated later completely. Smaller discrepancies in the integration of systems of balance equations for inhomogeneous flow are the consequence. The procedure is verified on various flow patterns, and comparisons are made with other conventional methods and with some available experimental data. Despite investigating only numerical examples of incompressible flows here, the technique, in principle, is capable of dealing with compressible flows as well. Furthermore, the proposed method discards some variables required in other techniques while still providing useful and acceptable results for practical problems.

Solvation of calcium ion in methanol: Comparison of diffraction studies and molecular dynamics simulation

Molecular dynamics simulation and diffraction (X-ray and neutron) studies were compared on 1 and 2 M methanol solutions of calcium chloride with aiming at the determination of the solution structures. Beyond that, the capabilities of the methods to describe solution structure are discussed. It has been found that diffraction methods are performing very well in determination of Ca 2+–O distances (2.39 Å in average). Further on, by applying the X-ray diffraction method ion pairs could be observed easily for higher concentrated solution, but for neutron diffraction study, the most adequate isotope substitution method has to be chosen with care in order to be able to detect ion pairs in solution. The results of molecular dynamic simulation were found to be in general accordance with the experimental findings. The smaller discrepancies between simulation and experimental results are coming from small differences in the ion–methanol and ion–ion distances, and they may be due to both the potential model applied in the simulation and to the experimental uncertainties.

Algoritmo de Controle de Potência Distribuído Fundamentado no Modelo Populacional de Verhulst

In this paper the continuous dynamic model of Verhulst is used. It had been elaborated initially to describe the population growth of biological species with food and physical space restrictions, in order to synthesize a new Distributed Power Control Algorithm (DPCA) applicable in Direct Sequence Code Division Multiple Access (DSCDMA) systems. The discretization of the corresponding differential equation is accomplished via Numeric Integration Euler method (NIE). Analytical convergence conditions for the proposed DPCA were also established. The properties of the proposed recursive algorithm, as Euclidian distance from optimum vector after convergence, convergence speed, Normalized mean Squared Error (NSE), average power consumption per user and implementation complexity are investigated through simulations. The simulation results are confronted with two another DPCA: the classic algorithm derived by Foschini and Miljanic and the sigmoidal of Uykan and Koivo. With estimation errors the proposed DPCA showed smaller discrepancy from the optimum power vector allocation after convergence and better convergence. Additionally, the Gerschgorin Circles theory (GC) is applied for the feasibility of the power allocation problem.

Collisional-radiative model in air for earth re-entry problems

A nonlinear time-dependent two-temperature collisional-radiative model for air plasma has been developed for pressures between 1kPa and atmospheric pressure to be applied to the flow conditions of space vehicle re-entry into the Earth’s atmosphere. The model consists of 13 species: N2, O2, N, O, NO, N2+, O2+, N+, O+, NO+, O2−, O− in their ground state and major electronic excited states and of electrons. Many elementary processes are considered given the temperatures involved (up to 10 000K). Time scales to reach the final nonequilibrium or equilibrium steady states are derived. Then we apply our model to two typical re-entry situations and show that O2− and O− play an important role during the ionization phase. Finally, a comparison with existing reduced kinetic mechanisms puts forward significant discrepancies for high velocity flows when the flow is in chemical nonequilibrium and smaller discrepancies when the flow is close to chemical equilibrium. This comparison illustrates the interest of using a time-dependent collisional-radiative model to validate reduced kinetic schemes for the relevant time scales of the flows studied.

Effects of three different network models on the filter coefficient of brownian particles

The dynamic behavior of granular filtration is investigated in the present paper by using the Brownian dynamic simulation method to track the individual particles moving through the 2-D network model of porous media in the filter bed. The scope includes three different network structures, modified square, triangular and honeycomb, all with the same initial permeability, and two types of DLVO interaction energy curves. The specific filtration functions of F 1( α′, σ) and F 2( β′, σ) are determined from the breakthrough curve of effluent concentration and the pressure drop. When comparing those three different network models with the same interaction energy curve, it is found that the honeycomb network can filtrate particles the easiest, because of its lowest coordination number, so its corresponded specific deposit σ is the highest. When comparing with the available experimental data under the unfavorable deposition conditions, it is found that the present triangular network gives smaller discrepancy than that of the convective diffusion model.

Non-independent randomized rounding and coloring

We propose an advanced randomized coloring algorithm for the problem of balanced colorings of hypergraphs (discrepancy problem). Instead of independently coloring the vertices with a random color, we try to use structural information about the hypergraph in the design of the random experiment by imposing suitable dependencies. This yields colorings having smaller discrepancy. We also obtain more information about the coloring, or, conversely, we may enforce the random coloring to have special properties. There are some algorithmic advantages as well. We apply our approach to hypergraphs of d -dimensional boxes and to finite geometries. Among others results, we gain a factor 2 d / 2 decrease in the discrepancy of the boxes, and reduce the number of random bits needed to generate good colorings for the geometries down to O ( n ) (from n ). The latter also speeds up the corresponding derandomization by a factor of n .

THE THEORETICAL PREDICTION FOR THE MUON ANOMALOUS MAGNETIC MOMENT

▪ Abstract This article reviews the standard-model prediction for the anomalous magnetic moment of the muon and describes recent updates of QED, electroweak, and hadronic contributions. Comparison of theory and experiment suggests a 2.4 σ difference if [Formula: see text] hadrons data are used to evaluate the main hadronic effects, but a smaller discrepancy if hadronic τ decay data are employed. Implications of a deviation for “new physics” contributions, along with an outlook for future improvements in theory and experiment, are briefly discussed.

Accuracy of the volume and pressure displays of high frequency oscillators

Objective: To determine the effect of frequency on the accuracy of volume and pressure displays of high frequency oscillators. Methods: The effect of frequency on the displayed volume of the...

Accuracy of the volume and pressure displays of high frequency oscillators

<b>Objective:</b> To determine the effect of frequency on the accuracy of volume and pressure displays of high frequency oscillators. <b>Methods:</b> The effect of frequency on the displayed volume of the Stephanie, Dräger Babylog 8000 Plus, and SLE 5000 oscillators was assessed. A sine wave pump delivered a constant tidal volume at frequencies of 5–15 Hz to the patient manifold of the oscillators. The displayed volumes at each frequency were compared with the delivered volume. The effect of frequency on displayed pressure was assessed by connecting the oscillator’s patient manifold to a lung model; three types of oscillator were studied (SensorMedics 3100A, SLE 5000, and Stephanie). Airway pressure was measured from the manifold using a pressure transducer and non-compliant tubing; the pressure measuring system had a flat frequency response to 30 Hz. <b>Results:</b> The SLE 5000 volume display overread the delivered volume (by about 5%), but was not affected by frequency. At 5 Hz, the Dräger Babylog 8000 Plus and the Stephanie underread the delivered volume (by about 20%). Increasing frequency resulted in a greater discrepancy between the delivered and displayed volume with the Stephanie, but a smaller discrepancy with the Dräger Babylog 8000 Plus. Altering frequency had a small effect (maximum difference 6%) on the relation between the displayed and delivered pressure for all three oscillators. <b>Conclusion:</b> Frequency affects the accuracy of displayed volumes and, to a lesser extent, displayed pressures of high frequency oscillators. The results emphasise that data displayed by new devices should not be uncritically accepted.

Nonexperimental Versus Experimental Estimates of Earnings Impacts

To assess nonexperimental (NX) evaluation methods in the context of welfare, job training, and employment services programs, the authors reexamined the results of twelve case studies intended to replicate impact estimates from an experimental evaluation by using NX methods. They found that the NX methods sometimes came close to replicating experimentally derived results but often produced estimates that differed by policy-relevant margins, which the authors interpret as estimates of bias. Although the authors identified several study design factors associated with smaller discrepancies, no combination of factors would consistently eliminate discrepancies. Even with a large number of impact estimates, the positive and negative bias estimates did not always cancel each other out. Thus, it was difficult to identify an aggregation strategy that consistently removed bias while answering a focused question about earnings impacts of a program. They conclude that although the empirical evidence from this literature can be used in the context of training and welfare programs to improve NX research designs, it cannot on its own justify the use of such designs.

U-measure: A quality measure for multiobjective programming

A multiobjective programming algorithm may find multiple nondominated solutions. If these solutions are scattered more uniformly over the Pareto frontier in the objective space, they are more different choices and so their quality is better. In this paper, we propose a quality measure called U-measure to measure the uniformity of a given set of nondominated solutions over the Pareto frontier. This frontier is a nonlinear hyper-surface. We measure the uniformity over this hyper-surface in three main steps: 1) determine the domains of the Pareto frontier over which uniformity is measured, 2) determine the nearest neighbors of each solution in the objective space, and 3) compute the discrepancy among the distances between nearest neighbors. The U-measure is equal to this discrepancy where a smaller discrepancy indicates a better uniformity. We can apply the U-measure to complement the other quality measures so that we can evaluate and compare multiobjective programming algorithms from different perspectives.

Stability of body image and body image dissatisfaction in American college students over about the last 15 years

It is widely assumed that body image dissatisfaction is increasing, particularly in females. We examined data from comparable samples, University of Pennsylvania introductory psychology students, over a span of about 15 years (1983–1984 versus 1995–1998). Ratings of current and ideal body figure were obtained using silhouettes, along with self-reported height and weight. While males always had a much smaller discrepancy between current and ideal than females, levels of dissatisfaction and gender differences in satisfaction have remained the same in these samples. This finding contrasts with the conclusion of a meta-analysis by Feingold and Mazzella in 1998 (Psychological Science9 (3), 190–195), which indicates an increased difference in body image satisfaction between men and women over the last two decades. Possible accounts for this difference in results are discussed.

Solubility of β-carotene in supercritical CO 2 and the effect of entrainers

Solubilities of trans- β-carotene in supercritical CO 2, both pure and modified, were measured at temperatures 313.2, 323.2 and 333.2 K and pressures up to 28 MPa using a one-pass flow apparatus. The solubility data measured in pure CO 2 were correlated by the density-based equation proposed by Chrastil, and modelled using the Soave-Redlich-Kwong cubic equation of state. Most of the literature data were in good agreement with our results; smaller discrepancies were ascribed mostly to β-carotene degradation. While ethanol entrainer increased the solubility of β-carotene in supercritical CO 2 by one order of magnitude, vegetable oil was less efficient. In both cases, the increase in solubility was proportional to square root of entrainer concentration.

Judgements of food healthfulness: food name stereotypes in adults over age 25

Previous findings indicated that college-aged women (compared to men) were more likely to use stereotypes when judging food names by their healthfulness. The present study is a replication and extension of an earlier study, using older (i.e. not traditional college age) participants (Mage=46). In general, men had fewer and smaller discrepancies between their evaluations of food names and descriptions than did females. As previously found, gender differences occurred for evaluations of food names rather than nutrient descriptions, with women using less information than men. The stereotype women used when judging food names involved negative attitudes toward dietary fat, whereas men appeared to take account of vitamin and mineral content in addition to fat. The older sample was generally more accurate (i.e. had smaller discrepancies when judging food names and descriptions) than were the previous sample of younger adults. Also, the current sample of older adults used more characteristics when evaluating food healthfulness of descriptions than did the previous sample of college students, indicating a more complex strategy of evaluating healthfulness of food descriptions.

Taking a Look Underground: Detecting, Interpreting, and Reacting to Implicit Racial Biases

Abstract Participants were given the opportunity to gain insight into their implicit racial biases by completing the Implicit Association Test (IAT, Greenwald, McGhee, & Schwartz, 1998). We examined participants' detection of their implicit racial biases, and their interpretation of and reactions to such biases. Further, we examined the potential moderating role of proneness to prejudice-related discrepancies. Results revealed strong implicit racial biases that were moderately related to explicit prejudice but unrelated to proneness to discrepancies. The majority of participants detected this bias, and they felt guilty about it to the extent that they attributed the bias to race-related factors. Participants with smaller discrepancies were more prone to misattribute their IAT bias to nonracial factors and not feeling guilty. These latter findings suggest that people who typically experience success at avoiding prejudiced responses might, paradoxically, be least likely to detect subtle racial biases when t...

Estimating denitrification in a large constructed wetland using stable nitrogen isotope ratios

Nitrate losses and their relationships to nitrogen isotope fractionation were evaluated in a wetlands environment in southern California. This paper reports the first study to follow isotope ratio changes in a large natural system with extensive macrophyte growth. As NO 3 concentrations decreased during flow through the wetlands, progressive enrichment in 15NO 3 was found. This increase corresponded to an enrichment value of −2.5‰, a value much lower that those reported for laboratory studies of denitrification (−17 to −29‰), but closer to the range of enrichment factors attributed to denitrification in studies of groundwaters (−3.5 to −16‰). By considering a laboratory derived value of −17‰ as the enrichment factor strictly due to denitrification, 10–23% of the Prado losses could be attributed through isotope enrichment to denitrification. Other studies at Prado, using a mass balance approach which considered macrophyte growth, concluded that bacterial denitrification was the major loss mechanism (89–95%). A similar, but somewhat smaller discrepancy between estimates of denitrification was found in nearby wetlands with large shallow water bodies with dense phytoplankton growth but negligible macrophytes. These discrepancies suggest that enrichment or fractionation factors derived under laboratory conditions where all nitrogen losses are attributable to denitrification cannot be used directly as the denitrification end-member in field situations where organic matter decomposition and nitrogen recycling are occurring simultaneously or sequentially with denitrification. Further studies which consider entire growing and decomposition cycles in macrophyte-rich wetlands are needed to resolve the discrepancy in the various methods of estimating dentrification in natural wetlands.

New Analytical Solution for Pyle-Popovich's Peritoneal Dialysis Model.

Continuous Ambulatory Peritoneal Dialysis (CAPD) is one of the standard treatments for kidney disease patients. A washing solution, called dialysate, is put into the peritoneal cavity to remove waste products and excess amounts of water in CAPD. The dialysate is exchanged four to five times a day by the patient. However, it is not easy to prescribe CAPD therapy, which may have precluded popularization of CAPD therapy. Popovich et al. constructed a mathematical model (P-P model) that applies to the prescription of the treatment schedule. It requires, however, a number of iterative calculations to obtain an exact numerical solution because the model is a set of nonlinear simultaneous ordinary differential equations. In this paper, the authors derived a new approximated analytical solution by employing a time-discrete technique, assuming all the parameters to be constant within each piecewise period of time for the P-P model. We have also described an algorithm of a numerical calculation with the new solution for determining a set of unknown parameters in the P-P model. We compare the validation of the new solution for clinical use with another analytical solution (Vonesh’s solution).The new analytical solution consists of a forward solution (FW solution), that is the solution for the plasma and dialysate concentrations from ti to ti+1 (ti ti+1), and a backward solution (BW solution) from ti to ti–1 (ti–1 ti). The unknown parameters were determined by employing the Newton–Raphson method, a trial-and-error method and the modified Powell method in combination with FW and BW solutions.The new analytical solution show an excellent agreement with the exact numerical solution for entire dwelling time. Moreover, optimized parameters with the new analytical solution show much smaller discrepancy than those with Vonesh’s solution.Although the proposed method requires a slightly longer calculation time than Vonesh’s, it can simulate concentrations in plasma and dialysate for an entire single exchange in CAPD using the clinical data measured at arbitrary time. The proposed method may be useful for determining unknown parameters as well as for prescribing CAPD treatment.