Different Methods For Quantification Research Articles

Precision of Cerebrovascular Reactivity Assessment with Use of Different Quantification Methods for Hypercapnia Functional MR Imaging

Tools for noninvasive mapping of hemodynamic function including cerebrovascular reactivity are emerging and may become clinically useful to predict tissue at hemodynamic risk. One such technique assesses blood oxygen level-dependent (BOLD) MR imaging contrast in response to hypercapnia, but the reliability of its quantification is uncertain. The aim of this study was to prospectively investigate the intersubject and interhemispheric variability and short-term reproducibility of hypercapnia functional MR imaging (fMRI) in healthy volunteers and to assess the effects of different methods of quantification and normalization. Sixteen healthy volunteers, (7 women and 9 men) underwent hypercapnia fMRI with a clinical 1.5T scanner; 8 underwent scanning twice. We determined BOLD amplitude changes using a visually defined block design or automated regression to end-tidal (ET) carbon dioxide (CO2). Absolute percent signal intensity changes (PSC) were extracted for whole-brain, gray matter, and middle cerebral artery territory, and also normalized to ETCO2 change. Intersubject and intrasubject (between hemispheres and sessions) coefficients of variation (COV) were derived. We assessed the effects of different quantification methods on reproducibility indices using the t test and U tests. The mean change in ETCO2 was 7.8 +/- 3.3 mm Hg. Averaged BOLD increases varied from 2.54% to 2.92%. Short-term reproducibility was good for absolute PSC (4.8% to 10%) but poor for normalized PSC (range, 24% to 27% COV). Intersubject reproducibility varied between 11% and 23% for absolute PSC and, again, was poorer for normalized data (32% to 39%). Interhemispheric reproducibility of absolute PSC was excellent ranging between 1.24 and 2.16% COV. In conclusion, quantification of cerebrovascular reactivity with use of hypercapnia fMRI was found to have good between-session and very good interhemispheric reproducibility. The technique holds promise as a diagnostic tool, especially for sensitive detection of unilateral disease.

Food forensics: Analysis of food, raw and processed materials with molecular biological methods

The identification of species is vital for product quality control as well as for detection of fraud and even more so for the investigation of crimes when biological trace material is found. They all have in common that the correct assignment of biological samples to species is aggravated due to highly degraded (e.g. due to heavy processing) or low amounts of DNA. Here we present examples of successful identification of species and even varieties in raw and processed materials such as textiles, seafood and plant products. We also show the use of two different methods for quantification of fractions different species contributed to a sample.

Morphometry of the Retrobulbar Human Optic Nerve: Comparison between Conventional Sonography and Ultrafast Magnetic Resonance Sequences

To compare different methods for quantification of optic nerve and nerve sheath diameter. To apply a novel magnetic resonance protocol using half-Fourier acquired single-shot turbo spin-echo (HASTE) sequences to analyze optic nerve dimensions. Measurements were taken in right eyes of 33 subjects whose median age was 25 years. A-scan ultrasonography was repeated three times in straight gaze. B-scan ultrasonography was repeated three times in straight gaze and abduction. HASTE sequences were applied in straight gaze, analyzed twice by two different radiologists, and completely repeated in a subset of 10 subjects; 95% confidence intervals and coefficients of variation were calculated. HASTE sequences yielded high contrast between cerebrospinal fluid and optic nerve parenchyma. Acquisition time for each sequence was 1.5 seconds per slice. Optic nerve diameters decreased from 3.23 mm at 5 mm to 2.67 mm at 15 mm behind the eye. Sheath diameters decreased from 5.72 mm to 3.98 mm. A- and B-scan ultrasonography yielded significantly smaller diameters. For HASTE sequences, the coefficients of variation ranged from 2% to 7% and were significantly smaller than those obtained with ultrasonographic measurements (9%-13%). The precision of magnetic resonance imaging exceeds that of ultrasonographic methods for determining optic nerve and nerve sheath diameters. HASTE sequences appear particularly appropriate for investigating the retrobulbar optic nerve complex and may be useful in future studies quantifying axonal loss within the optic nerve.

Amyloid β1–40 Quantification in CSF: Comparison between Chromatographic and Immunochemical Methods

Background/Aims: Amyloid β (Aβ) is the principal component of senile plaques, one of the hallmarks of Alzheimer’s disease (AD). Evidence is accumulating that soluble aggregates (oligomers) of Aβ are important in the pathogenesis of AD. Methods: We compared three different methods for quantification of the 40 amino acid form of Aβ (Aβ₄₀) in CSF, two based on antibodies [ELISA and surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF) with antibody-coated arrays] and one based on direct binding of proteins to a protein array [SELDI-TOF and immobilized metal affinity [copper] (IMAC30)]. Results: CSF Aβ₄₀ concentration was only found to be significantly elevated in AD (127% of control levels; p = 0.0095) using SELDI-TOF with IMAC30 arrays. Conclusions: These data suggest that the measured Aβ level in CSF may differ depending on whether antibody-based methods are used or not, possibly caused by epitope masking due to Aβ oligomerization or to binding of Aβ to carrier proteins.

Indexing reliability for condition survey data

Abstract This paper discusses the application of existing methods for measuring reliability to collection condition survey data. The essential requirement of reliability is understood by conservators but has never been quantified. The relatively recent introduction of computer methods that calculate reliability is mentioned as a significant step towards introducing the practice of ensuring reliability during pilot studies. The paper discusses different methods of quantification, and their qualities, as well as the aims of assessing reliability for condition surveys. The most satisfactory methods, and choosing an appropriate level of reliability for conservation applications are suggested. However, no single number is offered as a standard. It is recommended that more than one index should be used. The paper also describes techniques to use indices to determine causes of disagreement, so reliability can be increased.

Quantification, Localization, and Expression of IGF-I and TGF-�1 During Growth Factor-Stimulated Fracture Healing

Because of the increasing interest on stimulating fracture healing, knowledge about the role and chronology of growth factors during the healing process is important. The purpose of this study was to quantify the protein concentration of IGF-I and TGF-beta1 during rat tibial fracture healing 5, 10, and 15 days after fracture using ELISA methods and to analyze the distribution of the proteins and the related mRNA expression in the fracture callus by immunohistochemistry and in situ hybridization. The following three groups were analyzed: Fractured tibiae intramedullary stabilized with K-wires coated with IGF-I and TGF-beta1 compared with fractures stabilized with uncoated K-wires and unfractured tibiae. The weight of the callus increased during the healing process in both experimental groups. The protein concentration of IGF-I and TGF-beta1 in the fracture callus showed significant changes between the investigated time points and treatment groups compared with the unfractured tibia. IGF-I increased with healing time whereas TGF-beta1 revealed a constantly elevated level at the investigated time points. Mesenchymal cells, osteoblasts, osteocytes, proliferating and immature chondrocytes, and osteoclasts expressed both growth factors. No differences in the expression and localization pattern of the growth factors were detectable among the groups. Using the different methods for quantification and visualization of the growth factors, no differences (except the increased IGF-I concentration at day 15 in the growth factor group) were seen between the normal and the growth factor-stimulated fracture healing as an indication for physiological healing after exogenous growth factor treatment.

Quantificação de micélio extrarradicular de fungos micorrízicos arbusculares em plantas cítricas: II. Comparação entre diferentes espécies cítricas e endófitos

Visando verificar a influência da utilização de diferentes métodos de quantificação de micélio extrarradicular ativo (MEA) e micélio extrarradicular total (MET) de fungos micorrízicos arbusculares (FMAs) e de diferentes hospedeiros nesta simbiose, foi realizado um experimento em casa de vegetação, com delineamento inteiramente casualizado e esquema fatorial: 3 espécies de FMAs (Glomus intraradices, G. etunicatum e G. clarum) e um controle sem FMA x 6 doses de P (0, 50, 100, 150, 200 e 250 mg kg-1 de substrato) x 2 plantas cítricas: tangerina cleópatra (Citrus reshni) e laranja caipira (Citrus sinensis), com 5 repetições por tratamento. Seis meses após o transplantio e inoculação das mudas, determinaram-se altura e diâmetro do caule, colheram-se as plantas e avaliaram-se matéria seca e nutrientes da parte aérea, porcentagem de colonização radicular e comprimento de MEA e MET pelos métodos de fluorescência induzida com diacetato de fluoresceína (FDA) e redução do iodonitrotetrazólio (INT). As doses crescentes de P proporcionaram redução da porcentagem de colonização radicular nos dois porta-enxertos estudados e aumentos nas características altura, diâmetro, matéria seca da parte aérea e quantidade total absorvida de macro e micronutrientes por ambos os porta-enxertos. Houve correlação negativa entre comprimento de MEA e quantidade total absorvida de macronutrientes (P, N, Ca e Mg) por laranja caipira e correlação positiva entre comprimento de MET e quantidade absorvida por tangerina cleópatra, sugerindo ser esta última mais micotrófica que a anterior, além de haver, possivelmente, outros mecanismos de absorção de nutrientes que não pelo MEA, cujos resultados variaram em função do método empregado.

An analytical methodology to quantify the incorporation of enzymes in polyalkylcyanoacrylate nanoparticles based on size exclusion chromatography

The performances of different methods of quantification of protein (methods based on direct spectrophotometric and spectrofluorimetric analysis, chemical reactions and liquid chromatography) to quantify the amount of enzyme incorporated into polyalkylcyanoacrylate nanoparticles, were compared. A methodology based on size exclusion chromatography was selected. The performances of the analytical method to quantify the enzymes l-asparaginase and superoxide dismutase in different polymerization media of poly-isobutilcyanoacrylate, were evaluated. The quantification of superoxide dismutase in the presence of esterase, enzyme used to solubilize nanoparticles, was attempted. An adequate separation between enzyme and the other components of polymerization media was achieved, so the selectivity of the method is adequate to the quantification of an enzyme in polymerization medium, either before or after polymerization. Although lack of selectivity of the column to separate enzymes was observed. The retention time of L-asparaginase and superoxide dismutase in polymerization medium are, respectively, 7.4 and 7.5. Linear correlation between peak area and enzyme concentration were observed for both enzymes in the concentration range from 10 to 80 μg ml −1, either before or after polymerization and in different polymerization media. This SE-HPLC analytical methodology is adequate to determine the degree of incorporation of enzymes in polyalkylcyanoacrylate nanoparticles as evidenced by the linear responses of the chromatographic method, the reproductibility of repeated sample injections and the precision of the quantification of enzyme concentration.

Comparison of four quantification methods for the determination of PCB in transformer oils

The analysis of PCB in transformer oils has been achieved with three HRGC/ECD based methods, proposed by the International Electrotechnical Commission (IEC/TC 10), by the Comite Europeen de Normalisation (CEN/TC 19/WG 22) and by the Deutsches Institut fur Normung (DIN 51 527). The same clean-up, described in the CEN/TC 19/WG 22, has been used for all the samples, allowing a comparison of the quantification procedure only. The total chlorine content has also been determined with X-ray fluorescence. These different methods of quantification are compared and their application for legislative purposes is discussed.

Effects of resolution, peak ratio and sampling frequency in diode-array fluorescence detection in liquid chromatography

In this work, different methods of quantification that use both fluorescence spectral and retention time data were evaluated for accuracy and precision in diode-array fluorence detection in liquid chromatography. The methods evaluated include the peak height and peak area methods of quantification, an adaptive Kalman filter and the generalized rank annihilation method. All of these methods were used to estimate the concentration of a model led component in the presence of other partially resolved unmodelled components. The peak area and peak height methods of quantification gave the largest errors as the chromatographic resolution was decreased. The generalized rank annihilation method gave the most reliable results when the chromatographic resolution was greater than 0.3. However, this method was affected by retention time shifts between the calibration and unknown samples and the rate at which spectra were acquired.

Statistics of the hidden economy and informal activities inside the production boundary of the national accounts. An overview of national practices

In five chapters, this paper reviews definitions, activities, measurements, the scale and, finally, the hidden economy and national accounts. The first chapter examines different concepts and ap­ proaches to the definition of the hidden economy. It calls attention to the distinction between the macro-economic, micro-economic and institutional-economic approach. The second chapter reviews different kind of activities within the hidden economy. It emphasizes the importance of appropriate definition in regard to this aspect of the hidden economy. The third chapter examines different methods of quantification as developed in Western Europe, United Kingdom and United States. It reviews both indirect approaches (monetary, fiscal, national accounts) as well as methods of direct measurement. The fourth and fifth chapter deal with the scale of the hidden economy in various countries. While the fourth chapter mainly examines results of the different estimates of the hidden economy size, the fifth chapter looks at different country's practices and treatment of the hidden economy within the system of national accounts. In the general conclusion, the author essentially stresses the difficulty of defining and measuring such an elusive phenomenon.

The role of hippocampal commissures in the interhemispheric transfer of epileptiform afterdischarges in the rat: a study using linear and non-linear regression analysis

The role of the forebrain commissures and the septal area in the interhemispheric transfer of hippocampal afterdischarges (ADs) was investigated in the rat under halothane anesthesia. Electrical seizures were elicited from the dorsal hippocampus before and after commissurotomy. The degree of relatedness between EEG signals recorded from homologous sites of both hippocampi was quantified using two approaches: (i) a time domain analysis considering an AD as a succession of discrete bursts; the onset times of such bursts were measured and used to estimate interhemispheric onset delays; (ii) using signal analysis the linear ( r 2) and non-linear ( h 2)regression coefficients between pairs of EEG signals were computed as a function of time shift between the two signals. In this way the values of association (linear and non-linear) and the corresponding time delays were measured. In general a tetanus applied unilaterally to the dorsal CA3 field resulted in bilaterally synchronous ADs. The estimated interhemispheric time delay was in most cases zero. This bilateral synchrony disappeared after section of a specific part of the ventral hippocampal commissure (VHC), the dorso-caudal third, but was not affected by section of other commissural fibers or by a lesion of the septal area. This study also allowed evaluation of different methods of quantification of the association between EEG signals, namely the linear ( r 2) and the non-linear ( h 2) regression coefficients. The latter was shown to be a more robust measure than the former and to yield values of association even in cases in which r 2 was at noise level. The experimental findings allow the conclusion that ADs elicited from an epileptogenic focus spread to homologous sites in the contralateral hemisphere following commissural systems that may be strong enough to ensure the forming of one bilateral oscillating system.

Evaluation of Hematuria in Adults

GROSS hematuria (GH) or microscopic hematuria (MH) may be a clue to serious urologic disease, including malignancy. However, there is no consensus concerning either the level of MH to evaluate or the extent of the evaluation.^1-5In recent series, 39% to 90% of those with MH on screening urinalysis were not tested further.^3-5In those who were evaluated, an intravenous pyelogram (IVP) and cystoscopy were commonly not performed. With these points in mind, I will review the subject of hematuria in adults. <h3>DEFINITION AND DEMOGRAPHICS OF MH</h3> The marked variations in the reported upper limit of normal for urinary red blood cells (RBCs) in subjects without apparent renal disease are primarily due to the different methods of quantification (Table 1) and to the lack of control of activities just prior to urine collection that may induce transient MH (eg, mild trauma, exercise, viral illness, sexual activity, or digital

Comparison of different methods for quantification of urinary leakage in incontinent women

AbstractTo evaluate different methods for assessment of diagnosis and severity of urinary incontinence, 72 women underwent two consecutive 24 hours pad tests, a 1 hour pad test, a stress test, urodynamic examination, and a voiding‐cysto‐urethrography. The results were analysed and related to clinical findings.The 24 hours pad test revealed a good patient compliance, was as informative as to grade of incontinence as a 48 hours test, was reliable for all grades and types of incontinence, and correlated to clinical findings.The 1 hour pad test underestimated the grade of incontinence and was less correlated to clinical parameters than the 24 hours test.To estimate a level for pathological leakage, 25 continent controls underwent a 24 hours pad test. The results of the pad tests could be stratified by mean leakage per 24 hours as follows: up to 5 g in continent women, 40 g in mild incontinence, 80 g in moderate incontinence, and 200 g in severe incontinence.It could be concluded that a 24 hours home test was the pad test of choice for quantification and diagnosis of urinary incontinence.

Nuclear chromatin decondensation of human sperm assessed by DNA measurement.

A sperm nuclear decondensation ability test using 1% SDS + 6 mM EDTA was used to determine an objective method of quantification of the decondensation process by comparing two different methods of quantification: the usual histological method, after staining by the method of Shoor and classification of the sperm heads into normal heads, doubtful heads, swollen heads, and very swollen heads, and the measurement of the removal of DNA from the extremely swollen spermatozoa. After 5 min of exposure to SDS/EDTA, the percentage of removed DNA was correlated (negatively) to the percentage of normal heads, which assessed the two methods and confirmed that all decondensation results obtained after long periods of treatment with SDS/EDTA can be discarded since spermatozoa can be extremely swollen and disappear.

A note on the measurement, quantification, and use of consumer confidence

It is argued that consumer spending on durable items is not necessarily the only type of consumer spending to be influenced by consumer confidence but. given a certain degree of affluence. spending on non-durables can also be influenced by it. Different methods of quantification of consumer confidence are touched upon and the issue of equal weighting versus differential weighting, where weights are ascertained by the use of factor analysis, is discussed in more detail. Various indices of consumer confidence are computed and tested by means of regression analyses. It was found that it is immaterial whether a composite measure of confidence is based on factor analysis or simply on the summing and averaging of responses. The results of the regression analyses suggest that the hypothesis that consumer sentiment partly determines movements in private consumption expenditure holds true, especially in the case of durables. There are indications, however, that spending on non-durable goods might also be influenced by consumer sentiment.

The Role of Attitudes in Consumer Spending

SUMMARYThis paper comments very briefly on the central theme of work done on consumer sentiment and consumer expenditure. It is argued that consumer spending on durable items is not necessarily the only type of consumer spending to be influenced by consumer confidence but, given a certain degree of affluence, spending on non-durables can also be influenced by it. The paper then continues to investigate the use of sentiment data in the explaining of private consumption expenditure in South Africa.Quantification of consumer confidence is an extremely difficult exercise and this is emphasized in this paper. Different methods of quantification is touched upon and the issue of equal weighting versus differential weighting, where weights are ascertained by the use of factor analysis, is discussed in more detail. Various indices of consumer confidence are computed and tested by means of regression analyses.As is the case with economic magnitudes in general, attitudes are highly interrelated and this makes it difficult to assess their contribution to the explanation of changes in spending. The methods applied in the paper do suggest, however, that consumer sentiment measures are useful in this regard. This is true for measures derived from single questions as well as for those based on responses to more than one question. It was found that it is immaterial whether a composite measure of confidence is based on factor analysis or simply on the summing and averaging of responses.The results of regression analyses as discussed in the paper, as well as correlation analyses, suggest that the hypothesis that consumer sentiment partly determines movements in private consumption expenditure holds true, expecially in the case of durables. There are strong indications, however, that even spending on non-durable goods are influenced by consumer sentiment. A particularly important finding is that the sentiment measures perform best in lagged form which improves their use in short-term forecasting.

Methodological aspects of life events research

This paper reviews the methodology of studies of recent life events and illness, as relevant to psychosomatic studies. Three critical issues are discussed: the method of data collection; elimination of events which are consequences of illness; quantification of stress. It is concluded that the most important aspect is collection of data by careful interview technique covering defined events and time periods. Self-report event questionnaires, although heuristically valuable in the past, must now be regarded as inadequate. Exclusion of events which may be consequences of illness is also important in psychosomatic studies. Different methods of quantification produce refinements but are less crucial and alternative approaches may give similar results.

Demography in Roman History: Facts and Impressions

History is craving for definite results. At the end of the nineteenth century it was taught its lesson in a rude way. Historical evidence appeared to be fundamentally different from the evidence of the sciences. Dilthey and others vindicated its own position in the scholarly disciplines and proved, irrefutably I think, how many differences there are between the results of an historical investigation and those of, say, mathematical research. Time and again, however, new forms of positivism have come forward to declare proudly that history is a science in the same sense as the natural sciences. Presently, quantification of historical data seems to return to the history of classical antiquity not only under the urge of neopositivism, but also under the challenge of the impressive results which different methods of quantification attained for later periods of history, especially in the field of demography. A warning by an eminent modern scholar is not out of place, however. A. Momigliano sketches the situation in recent research as follows: negative fact [is] that full-blooded social history is becoming more and more intractable owing to its increasing refinements and complications. Anyone who follows with admiration the activities of the Sixi?me Section of the ?cole des Hautes ?tudes wonders whether such a microscopic analysis of social developments can be pursued indefinitely *). The learned and masterly book of Professor Brunt on Italian manpower 2) is in accordance with this renewed quantifying tendency in historiography. The results, however, prove that Dilthey was right. History, as a