Home About us Contact
|
Home About us Contact | ||
|
|
||
Preliminary Step (preliminary + step)
Selected AbstractsThe Efficacy of Curettage in Delineating Margins of Basal Cell Carcinoma Before Mohs Micrographic SurgeryDERMATOLOGIC SURGERY, Issue 9 2003Désirée Ratner MD Background. Curettage may be helpful as a preliminary step to outline the gross subclinical extensions of high-risk basal cell carcinomas (BCCs) before the first stage of Mohs micrographic surgery. Although many Mohs surgeons use curettage in the Mohs surgical setting, no prospective studies have as yet been performed that demonstrate the efficacy of curettage in delineating tumor margins before Mohs surgery. Objective. To document the efficacy of curettage in delineating BCC margins before Mohs micrographic surgery. Methods. This was a prospective evaluation of 599 patients with biopsy-proven BCCs treated with Mohs surgery. The preoperative dimensions of each tumor, the curetted dimensions before the first surgical stage, the proposed excisional margins before each surgical stage, and the final defect dimensions after each surgical stage were measured. The maximum curetted margin around each tumor was calculated and compared with typical Mohs excisional margins of 1, 2, 3, and 4 mm. A hypothetical 1-, 2-, 3-, or 4-mm excisional margin was added to the preoperative X and Y dimensions of each tumor, and the actual final defect sizes were compared with the hypothetical final defect sizes to determine whether an additional surgical stage would have been needed had curettage not been performed. The amount of tissue stretch occurring after specimen removal was calculated to determine whether tissue stretch falsely elevated the number of instances in which an additional surgical stage would have been needed had curettage not been performed. Results. The curetted margin around the observed extent of each tumor exceeded 1 mm in 87.6% of cases, 2 mm in 47.1% of cases, 3 mm in 19.7% of cases, and 4 mm in 5.7% of cases. The mean curetted margin was 1.7 mm. Taking a 1-mm margin in the first stage of Mohs surgery without first performing curettage would have necessitated an extra surgical stage in 99.2% of cases, whereas taking a 2-, 3-, or 4-mm margin would have necessitated an extra surgical stage in 93.0%, 88.1%, and 49.4% of cases, respectively. After calculating and eliminating the effects of tissue stretch, it was found that a 1-mm excisional margin taken in the first stage of Mohs surgery without first performing curettage would have necessitated an extra surgical stage in 99.0% of the cases. Taking a 2-, 3-, or 4-mm margin would have necessitated an extra surgical stage in 87.5%, 57.9%, and 29.5% of cases, respectively. Conclusion. Careful debulking and palpation with the curette significantly reduce the number of Mohs surgical stages required for BCC clearance. Even after taking the effects of tissue stretch into consideration, a significant proportion of tumors would still require an additional stage for tumor clearance without aggressive presurgical curettage. [source] Sample Splitting and Threshold EstimationECONOMETRICA, Issue 3 2000Bruce E. Hansen Threshold models have a wide variety of applications in economics. Direct applications include models of separating and multiple equilibria. Other applications include empirical sample splitting when the sample split is based on a continuously-distributed variable such as firm size. In addition, threshold models may be used as a parsimonious strategy for nonparametric function estimation. For example, the threshold autoregressive model (TAR) is popular in the nonlinear time series literature. Threshold models also emerge as special cases of more complex statistical frameworks, such as mixture models, switching models, Markov switching models, and smooth transition threshold models. It may be important to understand the statistical properties of threshold models as a preliminary step in the development of statistical tools to handle these more complicated structures. Despite the large number of potential applications, the statistical theory of threshold estimation is undeveloped. It is known that threshold estimates are super-consistent, but a distribution theory useful for testing and inference has yet to be provided. This paper develops a statistical theory for threshold estimation in the regression context. We allow for either cross-section or time series observations. Least squares estimation of the regression parameters is considered. An asymptotic distribution theory for the regression estimates (the threshold and the regression slopes) is developed. It is found that the distribution of the threshold estimate is nonstandard. A method to construct asymptotic confidence intervals is developed by inverting the likelihood ratio statistic. It is shown that this yields asymptotically conservative confidence regions. Monte Carlo simulations are presented to assess the accuracy of the asymptotic approximations. The empirical relevance of the theory is illustrated through an application to the multiple equilibria growth model of Durlauf and Johnson (1995). [source] Rapid Cooling Aborts Seizure-Like Activity in Rodent Hippocampal-Entorhinal SlicesEPILEPSIA, Issue 10 2000Matthew W. Hill Summary Purpose: As a preliminary step in the development of an implantable Peltier device to abort focal neocortical seizures in vivo, we have examined the effect of rapid cooling on seizures in rodent hippocampal-entorhinal slices. Methods: Seizure-like discharges were induced by exposing the slices to extracellular saline containing 4-aminopyridine (50 ,mol/L). Results: When we manually activated a Peltier device that was in direct contact with the slice, seizures terminated within seconds of the onset of cooling, sometimes preceding a detectable decrease in temperature measured near the top of the slice. However, activation of the Peltier device did not stop seizures when slices were no longer in direct physical contact with the device, indicating that this was not a field effect. When cooling was shut off and temperature returned to 33oC, bursting some-times returned, but a longer-term suppressive effect on seizure activity could be observed. In two of our experiments, a custom computer program automatically detected seizure discharges and triggered a transistor-transistor logic pulse to activate the Peltier device. In these experiments, the Peltier device automatically terminated the slice bursting in less than 4 seconds. When the Peltier device was placed in contact with the normal, exposed cortex of a newborn pig, we found that the cortical temperature decreased rapidly from 36oC to as low as 26oC at a depth of 1.7 mm below the cooling unit. Conclusions: These experiments show that local cooling may rapidly terminate focal paroxysmal discharges and might be adapted for clinical practice. [source] Bacterial diseases of tomato in southern Spain: application of a detached tissue assay to evaluate bacterial pathogenicityEPPO BULLETIN, Issue 2 2000F. M. Cazorla Tomatoes are one of the most important crops in southern Spain, especially during the cold season. As a preliminary step in the design of an integrated disease management programme for tomato, a study on the occurrence of bacterial diseases in tomato houses of Almería (ES) was carried out during the 1993/1997 growing seasons. Sixty-four bacterial strains were isolated from tomato plants showing symptoms of bacterial diseases and 41 of them (64%) were characterized as pathogenic. The bacterial tomato pathogens most frequently isolated were Erwinia carotovora subsp. carotovora, Pseudomonas corrugata, Pseudomonas syringae pv. tomato and Xanthomonas vesicatoria. The pathogenicity of the bacterial isolates on tomato was tested by the conventional seedling assay and by an in vitro assay using detached tissues developed in our laboratory. Close correspondence between the two assays was observed. An in vitro detached tissue assay is proposed for determining the pathogenicity of bacterial isolates on tomato. [source] Feedforward networks in financial predictions: the future that modifies the presentEXPERT SYSTEMS, Issue 3 2000Massimo Budcema The main goal of this paper is to show how relatively minor modifications of well-known algorithms (in particular, back propagation) can dramatically increase the performance of an artificial neural network (ANN) for time series prediction. We denote our proposed sets of modifications as the 'self-momentum', 'Freud' and 'Jung' rules. In our opinion, they provide an example of an alternative approach to the design of learning strategies for ANNs, one that focuses on basic mathematical conceptualization rather than on formalism and demonstration. The complexity of actual prediction problems makes it necessary to experiment with modelling possibilities whose inherent mathematical properties are often not well understood yet. The problem of time series prediction in stock markets is a case in point. It is well known that asset price dynamics in financial markets are difficult to trace, let alone to predict with an operationally interesting degree of accuracy. We therefore take financial prediction as a meaningful test bed for the validation of our techniques. We discuss in some detail both the theoretical underpinnings of the technique and our case study about financial prediction, finding encouraging evidence that supports the theoretical and operational viability of our new ANN specifications. Ours is clearly only a preliminary step. Further developments of ANN architectures with more and more sophisticated 'learning to learn' characteristics are now under study and test. [source] Towards a geography of transnational spaces: Indian transnational communities in AustraliaGLOBAL NETWORKS, Issue 1 2004Carmen Voigt-Graf In this article, the geography of the transnational spaces of Punjabis, Kannadigas and Indo-Fijians is analysed. Punjabis have constructed complex transnational spaces that are virtually global in scale. Kannadigas are engaged in transnational activities linking their places of residence with south India. Indo-Fijians have emerged as a regional transnational community stretching across the Pacific Ocean. On the basis of their experiences, a consistent terminology is suggested and a typology of different models of transnational spaces is developed. This typology provides a tool to compare different transnational communities beyond the Indian experience. It can be seen as a preliminary step in the direction of a more theoretical approach that links the geography of migrant transnational spaces with sociological debates on social space. [source] Lie detection by functional magnetic resonance imagingHUMAN BRAIN MAPPING, Issue 3 2002Tatia M.C. Lee Abstract The accurate detection of deception or lying is a challenge to experts in many scientific disciplines. To investigate if specific cerebral activation characterized feigned memory impairment, six healthy male volunteers underwent functional magnetic resonance imaging with a block-design paradigm while they performed forced-choice memory tasks involving both simulated malingering and under normal control conditions. Malingering that demonstrated the existence and involvement of a prefrontal-parietal-sub-cortical circuit with feigned memory impairment produced distinct patterns of neural activation. Because astute liars feign memory impairment successfully in testing once they understand the design of the measure being employed, our study represents an extremely significant preliminary step towards the development of valid and sensitive methods for the detection of deception. Hum. Brain Mapping 15:157,164, 2002. © 2002 Wiley-Liss, Inc. [source] Application of radial basis meshless methods to direct and inverse biharmonic boundary value problemsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 4 2005Jichun Li Abstract In this paper, we develop a non-iterative way to solve biharmonic boundary value problems by using a radial basis meshless method. This is an original application of meshless method to solving inverse problems without any iteration, since traditional numerical methods for inverse boundary value problems mainly are iterative and hence very time-consuming. Numerical examples are presented for inverse biharmonic boundary value problems and corresponding direct problems, since solving direct problems is a preliminary step for inverse problems. All our examples of direct and inverse problems are solved within seconds in CPU time on a standard PC, which makes our proposed technique a great potential candidate for wide-spread applications to other inverse problems. Copyright © 2004 John Wiley & Sons, Ltd. [source] The roles of science and technology in energy and environment research and developmentINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2001Ibrahim Dincer Abstract Countries are becoming increasingly aware of the importance of science and technology in relation to national development and the necessity of formulating a concise science and technology policy. The need to strengthen and orient the scientific and technological infrastructure in line with national development goals, through more effective use of an available qualified work force and the higher education system, is becoming widely recognized. Consequently, appropriate methods of assessing the impact of science and technology on national development are needed so that efforts are concentrated on areas potentially having substantial impacts. Numerous planning studies have been undertaken to this end, particularly by international organizations such as UNESCO, UNIDO, OECD and IEA. This study examines the inter-relationships of the disciplines of science and technology with energy and environment research and development (R&D) activities, particularly for developing countries. The connections between these topics are discussed along with some basic methods that can be used to exploit the relations. Some illustrative examples are presented. It is anticipated that the present study will serve as a preliminary step for more comprehensive work by providing an example of the utilization of formal methods in formulating science and technology policy for energy and environment R&D. Copyright © 2001 John Wiley & Sons, Ltd. [source] Internal energy distribution of peptides in electrospray ionization : ESI and collision-induced dissociation spectra calculationJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2008Alireza Pak Abstract The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to estimate and compare the internal energy distributions of different ions (different nature, degree of freedom ,DOF' and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vékey). The internal energy calibration is the preliminary step for ESI and collision-induced dissociation (CID) spectra calculation. meta -Methyl-benzylpyridinium ion and four protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compounds. Cone voltages (Vc) were linearly correlated with the mean internal energy values ( Validation of a quantitative assay using GC/MS for trace determination of free and conjugated estrogens in environmental water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003Asmaa Mouatassim-Souali Abstract It has been shown that sewage effluent can discharge human hormones and pharmaceuticals, particularly estrogens and synthetic chemicals, which are able to disrupt animal and human endocrine systems into surface waters. Since many surface waters receive sewage effluent and are subsequently used to produce drinking water, it is of principal interest to assess their contamination level and thereby their possible public health and environmental impact. To date, no data concerning the occurrence of estrogens present in the French aquatic environment are available. We therefore developed and validated an analytical procedure, which allows simultaneous quantitative determination of three natural estrogens, 17,-estradiol, estriol, and estrone and one of the synthetic estrogens most widely used in contraception, ethinylestradiol, in water. Water samples are extracted using solid-phase extraction (SPE) and then separated by gas-chromatography coupled with mass spectrometric detection. Under our conditions, detection limits of estrogens reached the pg range of injected sample, i. e. less than 0.1 ng L,1. Conjugated estrogens were also investigated using the same procedure as described above but with a enzymatic hydrolysis preliminary step before extraction. The analysis of samples collected from four wastewater treatment plants and from surface water showed significant concentrations of estrogens ranging from 2 to 18 ng L,1 and from 0.5 to 3 ng L,1, respectively. Furthermore, no estrogen conjugated forms were detected in the water samples. [source] Firm strategy, innovation and consumer demand: a market process approachMANAGERIAL AND DECISION ECONOMICS, Issue 4-5 2001Paul L. Robertson Despite recent advances by economists such as Porter and those associated with the resource-based school, the economics of demand rarely features in discussions of business strategy. Porter and the resource-based school take the characteristics of demand as given, and place almost exclusive emphasis on the role of supply-side factors in formulating strategy. Scholars in strategic marketing, by contrast, recognize the importance of demand factors, but do not analyse them from an economic standpoint. Moreover, none of the important schools of strategic management attempts to explore the relationship between supply and demand in much analytical depth. In this paper, we adopt a market process approach to strategy formulation as a preliminary step towards rectifying these problems. First, we explore the factors that affect the economics of demand, particularly in innovative situations. Second, we adapt Lancaster's attribute analysis to show how the interaction between supply and demand can be represented from a market process perspective. On the basis of our efforts, we conclude that further work in these areas would benefit students of both strategic management and economics. Copyright © 2001 John Wiley & Sons, Ltd. [source] A study on the optimization of the deployment of targeted observations using adjoint-based methodsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 583 2002Thierry Bergot Abstract A new adjoint-based method to find the optimal deployment of targeted observations, called Kalman Filter Sensitivity (KFS), is introduced. The major advantage of this adjoint-based method is that it allows direct computation of the reduction of the forecast-score error variance that would result from future deployment of targeted observations. This method is applied in a very simple one-dimensional context, and is then compared to other adjoint-based products, such as classical gradients and gradients with respect to observations. The major conclusion is that the deployment of targeted observation is strongly constrained by the aspect ratio between the length-scale of the sensitivity area and the length-scale of the analysis-error covariance matrix. This very simple example also clearly illustrates that the reduction of forecast-error variance is stronger for assimilation schemes which have a smaller characteristic length-scale. Finally, the KFS technique is applied in a diagnostic way (i.e. once the observations are done) to four FASTEX cases. For these cases, the reduction of the forecasterror variance is in agreement with the efficiency of targeted observations as previously studied. A preliminary step towards an operational use has been performed on FASTEX IOP18, and results seem to validate the KFS approach of targeting. Copyright © 2002 Royal Meteorological Society. [source] Single-step purification of the recombinant green fluorescent protein from intact Escherichia coli cells using preparative PAGEELECTROPHORESIS, Issue 17 2009Few Ne Chew Abstract Mechanical and non-mechanical breakages of bacterial cells are usually the preliminary steps in intracellular protein purification. In this study, the recombinant green fluorescent protein (GFP) was purified from intact Escherichia coli cells using preparative PAGE. In this purification process, cells disruption step is not needed. The cellular content of E. coli was drifted out electrically from cells and the negatively charged GFP was further electroeluted from polyacrylamide gel column. SEM investigation of the electrophoresed cells revealed substantial structural damage at the cellular level. This integrated purification technique has successfully recovered the intracellular GFP with a yield of 82% and purity of 95%. [source] Use of sweet sorghum juice for lactic acid fermentation: preliminary steps in a process optimizationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010Kata Hetényi Abstract BACKGROUND: Lactic acid has many applications in the chemical industries and it can be produced economically by microorganisms using biomass raw materials of different origins. Sweet sorghum juice is a high sugar content raw material with potential for lactic acid production because after hydrolysis of its sucrose content the remaining glucose and fructose can supply the carbon demand of most lactic acid bacteria. However, satisfying the nitrogen and B-vitamin needs of the bacteria by supplementation with yeast extract and/or other alternative nitrogen-containing supplements can make the process too expensive. RESULTS: Using a statistical optimization process much of the yeast extract can be replaced by a cheaper alternative nitrogen source, namely wheat gluten. This resulted in a fermentation with 99% lactic acid yield and 3.04 g L,1 h,1 volumetric productivity. CONCLUSION: Using response surface methodology (RSM) media optimization was performed for lactic acid fermentation with an industrially acceptable result, reducing the costs of raw materials by half, replacing yeast extract by an alternative nitrogen source and applying yeast extract only as a source of micro-elements (vitamins, salts, etc.) Copyright © 2010 Society of Chemical Industry [source] Relevance of European alignment for micronutrients' recommendation regarding pregnant and lactating women, infants, children and adolescents: an insight into preliminary steps of EURRECAMATERNAL & CHILD NUTRITION, Issue 2010Irene Cetin No abstract is available for this article. [source]
| | |||||||||||||||||||||