Mean Values Of Samples Research Articles

Antecedents of mass customization capability: Direct and interaction effects

Research suggests that flexible manufacturing resources, customer involvement, and product management tools contribute to a high level of mass customization capability. Conceptualizing these antecedents as resource types, we examine hypotheses about their direct and complementary effects on mass customization capability. Analyzing secondary survey data from 238 plants in eight countries and three industries via hierarchical linear regression, we find that each individual resource type has a positive direct effect on mass customization capability, as long as the levels of the other two resources are at their sample mean value. Probing these results via conditional effects and marginal effects plots provides partial support for the complementarity argument, and unveil complex nonlinear interactions among the three resource types. When the level of one resource type is low, the two remaining resource types exhibit a strong bivariate complementary effect on mass customization capability. Conversely, when one resource type is at a high level, the complementary effect on mass customization capability of the two remaining resource types disappears and is replaced by a cancellation effect. The detection of complementary effects and of cancellation effects are two specific theoretical contributions to the literature on how manufacturers can enhance their capability to mass customize.

Pre-impoundment Macroinvertebrate Composition of Elemi River, Ado-Ekiti, Ekiti State, Nigeria

Benthic organisms are generally considered to be good indicators of environmental conditions of aquatic ecosystem. The present study was undertaken to study the pre-impoundment composition, abundance, distribution and diversity of the macroinvertebrate fauna of Elemi River, Ado-Ekiti, while using these organisms as water-quality bioindicators. Physicochemical, metals and benthic samples were collected biweekly at four stations between April –July, 2015, using standard methods of APHA (1998). The mean values of triplicate samples of physicochemical parameters include pH (6.82±0.06), temperature (27.05°C ± 4.35), TDS (0.07 ± 0.0001), DO (11.15 ± 1.88), BOD (5.8 ± 0.71), NO3 (57.08 ± 6.48), SO4 (76.14 ± 10.4). For the metals, the mean values are Pb (0.01 ± 0.0001), Cr (0.21 ± 0.04), Cu (0.07 ± 0.003), Mg (152.68 ± 79.5), Zn (2.05 ± 5.19), and Fe (1.98 ± 0.21). When compared with the WHO permissible standards for freshwaters, DO, BOD and NO3 had mean values that were significantly higher than the WHO standards for drinking and agricultural purposes. Also, metals including Cr, Mg, Zn, and Fe had mean values significantly higher than the WHO standards. Seven families of macroinvertebrates representing five orders of Mollusca (66.6%), Coleoptera (14.6%), Plecoptera (12.7%), Hemiptera (4.3%), and Tricoptera (1.8%) were recorded during the period of study. Of the total collected macroinvertebrates, insects comprised only 33.4%, but they are more diverse compared with the gastropods which made up the highest (66.6%) percentage, but are less diverse. Their high abundance coupled with high concentrations of some physicochemical parameters indicates high impact of anthropogenic activities and may result into high organic pollution of the river. Elemi River thus experiences degradation as it flows downstream and benthic macroinvertebrates can serve as a good biological indicator to monitor the river health.

Bootstrap tests for mean value differences over fuzzy samples

This paper aims to statistically test the null hypothesis H∞ for equality of the mean values of 1D continuous parameter in two different populations, each represented by a fuzzy sample of i.i.d. observations. A degree of membership to the corresponding population is assigned to any of the observations in the fuzzy sample. A Bootstrap algorithm is developed for simulation-based approximation for the CDF of the difference between the sample means, provided that H∞ is true. The needed pvalue of the statistical test is derived using the constructed conditional distribution of the test statistic. The main idea of the proposed Bootstrap test is that, if H∞ is true, then each sample can be shifted so that to have mean value equal to the fuzzy mean value of the united fuzzy sample. The two shifted fuzzy samples are summarized into conditional sample distributions of the 1D continuous parameter used for generation of synthetic couples of fuzzy samples in different pseudo-realities. The proposed algorithm has eight modifications, which differ by the method to generate the synthetic fuzzy sample, by the type of the conditional sample distributions derived from the shifted fuzzy samples, and by the type of the statistical test performed (one-tail or two-tail test). Numerical example are included to demonstrate the proposed algorithm.

The effect on the flexural strength, flexural modulus and compressive strength of fibre reinforced acrylic with that of plain unfilled acrylic resin - an in vitro study.

The aim of this in vitro study was to compare the flexural strength, the flexural modulus and compressive strength of the acrylic polymer reinforced with glass, carbon, polyethylene and Kevlar fibres with that of plain unfilled resin. A total of 50 specimens were prepared and divided into 10 specimens each under 5 groups namely group 1- control group without any fibres, group 2 - carbon fibres, group 3- glass fibres, group 4 - polyethylene, group 5- Kevlar. Universal testing machine (Tinius olsen, USA) was used for the testing of these specimens. Out of each group, 5 specimens were randomly selected and testing was done for flexural strength using a three point deflection test and three point bending test for compressive strength and the modulus was plotted using a graphical method. Statistical analysis was done using statistical software. The respective mean values for samples in regard to their flexural strength for PMMA plain, PMMA+ glass fibre, PMMA+ carbon, PMMA+ polyethylene and PMMA+ Kevlar were 90.64, 100.79, 102.58, 94.13 and 96.43 respectively. Scheffes post hoc test clearly indicated that only mean flexural strength values of PMMA + Carbon, has the highest mean value. One-way ANOVA revealed a non-significant difference among the groups in regard to their compressive strength. The study concludes that carbon fibre reinforced samples has the greatest flexural strength and greatest flexural modulus, however the compressive strength remains unchanged.

Ex vivo estimation of photoacoustic imaging for detecting thyroid microcalcifications.

BackgroundThe aim of this study was to evaluate the diagnostic utility of PAI at detecting thyroid microcalcifications at 700 nm laser wavelengths.MethodsThis study included 36 resected samples in 18 patients. To evaluate the PA manifestation of microcalcifications in PAI, gray level histogram and co-occurrence matrix (COM) texture parameters were extracted from the 3 fixed ROI US and PA images, respectively, per sample. We compared the textural parameters obtained from specimen PAIs between samples with punctate microcalcifications on specimen radiography and those without microcalcifications.ResultsOn specimen US, the mean value (2748.4±862.5) of samples with microcalcifications on specimen radiography was higher than that (1961.9±780.2) of those without microcalcifications (P = 0.007). However, there were no significant differences in textural parameters obtained from specimen PAIs between samples with punctate microcalcifications on specimen radiography and those without when applying both the mean value of the three slices of thyroid specimens and the value of the thyroid specimen slice which had the highest value of the mean values in specimen US.ConclusionPAI did not show significant PA contrast on thyroid microcalcifications indicating that the experimental setup and protocols should be enhanced, e.g., method of complete blood rejection from ex vivo specimens, the multi-wavelength spectroscopic PA imaging method which can solely extract the PA signal from microcalcifications even with high spectral interferences, or PA imaging with narrower slice thickness using 2-dimensional array transducer, etc.

Implications of short‐range spatial variation of soil bulk density for adequate field‐sampling protocols: methodology and results from two contrasting soils

SummarySoil bulk density (BD) is measured during soil monitoring. Because it is spatially variable, an appropriate sampling protocol is required. This paper shows how information on short‐range variability can be used to quantify uncertainty of estimates of mean BD and soil organic carbon on a volumetric basis (SOCv) at a sampling site with different sampling intensities. We report results from two contrasting study areas, with mineral soil and with peat. More sites should be investigated to develop robust protocols for national‐scale monitoring, but these results illustrate the methodology. A 20 × 20‐m2 monitoring site was considered and sampling protocols were evaluated under geostatistical models of our two study areas. At sites with local soil variability comparable to our mineral soil, sampling at 16 points (4 × 4 square grid of interval 5 m) would achieve a root mean square error (RMSE) of the sample mean value of both BD and SOCv of less than 5% of the mean (topsoil and subsoil). Pedotransfer functions (PTFs) gave predictions of mean soil BD at a sample site, comparable to our study area on mineral soil, with similar precision to a single direct measurement of BD. On peat soils comparable to our second study area, the mean BD for the monitoring site at depth 0–50 cm would be estimated with RMSE to be less than 5% of the mean with a sample of 16 cores, but at greater depths this criterion cannot be achieved with 25 cores or fewer.

Determination of Elements Leachability from Sarcheshmeh Porphyry Copper Mine Tailings: Application of Toxicity Characteristic Leaching Procedure

The Toxicity Characteristic Leaching Procedure (TCLP) was applied in order to determine the leachability and mobility of different trace metals and metalloids from the Sarcheshemh Cu mine tailings. Twenty one solid samples were collected from weathered and fresh tailings and also from evaporative secondary minerals and efflorescence salts associated with the oxidation zone of dried tailings. According to the TCLP results, the most leachable and mobile trace elements are Ag, Al, Cd, Ni, S, Se, Co, Cr, Cu, Fe, Mn and Zn. These contaminant elements were concentrated in the surface evaporative layer formed on the top of old weathered tailings. Very high concentrations of Al (27,600 mgL−1), Cu (56,900 mgL−1), Mn (13,260 mgL−1), S (151,800 mgL−1), and Zn (3,935 mgL−1) were observed in the TCLP results of the evaporative samples (mean values are presented). The results obtained from evaporative and efflorescence samples were higher than the regulatory levels for Al, Cu, Cd, Ni, Se, and Zn. The maximum leachability was found for Al and Cu, followed by Ni, Cd, Zn, and Se. The results of this study are useful for the prediction of contamination potential of trace elements and environmental management of mine tailings.

Evaluation of natural gamma radiation and absorbed gamma dose in soil and rocks of Perambalur district (Tamil Nadu, India)

The activity concentrations and absorbed gamma dose of primordial radionuclides 238U, 232Th and 40K were determined employing γ-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg−1 for 238U, 66 Bq kg−1 for 232Th and 340.3 Bq kg−1 for 40K as compared to mean values for rock samples (238U—8.0 Bq kg−1; 232Th—65.1 Bq kg−1; 40K—199.1 Bq kg−1). The mean absorbed gamma dose rate for soil (61.4 nGy h−1) marginally exceeded the prescribed limit of 55 nGy h−1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h−1. The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg−1) than in rock (20.0 Bq kg−1). However, these values were lower than the limit (370 Bq kg−1) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district.

A Survey of the Processing and Chemical Composition of Gariss Produced by Nomadic Camel Women Herders in Al Gaderif State , Sudan

Gariss is the most popular stable food for the camel herders who depend on Gariss for the sustainability of their livestock. The objective of the current study is to assess the traditional fermented camel milk (Gariss) prepared by nomadic camel woman herders in AlGadarif State in Butana. It is also meant to improve the quality of camel milk products through sharing knowledge. The samples (n= 19) were collected during rainy and dry seasons. The nomad’s housekeepers were interviewed in the study area. The effect of different types of containers and the additives used during Gariss preparation and the compositional quality were all estimated. The survey reported the different types of spoilage and the variations in the shelf life of Gariss. When compared with the mean values of the Gariss samples collected during dry season, the result indicated that the values of the total solids and the pH of the samples collected during the rainy season were significantly higher (p<0.05), whereas the values of the fat, protein and ash were significantly lower (p<0.05). The container types had a significant (p<0.05) effect on the total solids, fat and ash content only. The Gariss prepared in Bukhsa showed the highest total solids content (13.15±0.54%) and that prepared in stainless steel showed the highest fat (4.65± 0.34%) content. However, when Gariss was prepared in plastic containers it showed the lowest pH value (3.59±0.16%), whereas samples from ‘‘Siin’’ (goat leather) was significantly lower (p<0.05) in the ash content (0.35± 0.09%). The present study concludes that the chemical composition of Gariss from the nomadic camel women herders is affected by seasons, types of additives and containers used. Hence more studies are needed to be done on the effect of the additive and containers on Gariss quality.

Goal-oriented sensitivity analysis for lattice kinetic Monte Carlo simulations

In this paper we propose a new class of coupling methods for the sensitivity analysis of high dimensional stochastic systems and in particular for lattice Kinetic Monte Carlo (KMC). Sensitivity analysis for stochastic systems is typically based on approximating continuous derivatives with respect to model parameters by the mean value of samples from a finite difference scheme. Instead of using independent samples the proposed algorithm reduces the variance of the estimator by developing a strongly correlated-"coupled"- stochastic process for both the perturbed and unperturbed stochastic processes, defined in a common state space. The novelty of our construction is that the new coupled process depends on the targeted observables, e.g., coverage, Hamiltonian, spatial correlations, surface roughness, etc., hence we refer to the proposed method as goal-oriented sensitivity analysis. In particular, the rates of the coupled Continuous Time Markov Chain are obtained as solutions to a goal-oriented optimization problem, depending on the observable of interest, by considering the minimization functional of the corresponding variance. We show that this functional can be used as a diagnostic tool for the design and evaluation of different classes of couplings. Furthermore, the resulting KMC sensitivity algorithm has an easy implementation that is based on the Bortz-Kalos-Lebowitz algorithm's philosophy, where events are divided in classes depending on level sets of the observable of interest. Finally, we demonstrate in several examples including adsorption, desorption, and diffusion Kinetic Monte Carlo that for the same confidence interval and observable, the proposed goal-oriented algorithm can be two orders of magnitude faster than existing coupling algorithms for spatial KMC such as the Common Random Number approach. We also provide a complete implementation of the proposed sensitivity analysis algorithms, including various spatial KMC examples, in a supplementary MATLAB source code.

Role of atomic variability and mechanical constraints on the martensitic phase transformation of a model disordered shape memory alloy via molecular dynamics

We use molecular dynamics (MD) with an embedded atom model potential parameterized for NiAl to study martensitic phase transformations in a disordered shape memory alloy. We focus on the role of intrinsic atomic-level variability and mechanical constraints on the martensite and austenite transformation temperatures and on the martensite microstructure for specimens with varying size. We find that periodic system size has a weak effect on transformation temperature all the way to the nanometer scale, with the entropy-stabilized austenite phase slightly penalized with decreasing size. Atomic-level variability in these random alloys leads to significant sample-to-sample variability in transformation temperature. The uncertainty in the austenite transformation temperature increases with decreasing size, reaching ∼10% of the mean value for samples 10nm on the side. Interestingly, the variability of the high-temperature martensite transition shows little size dependence. We find that a critical size of ∼40nm is required to develop multidomain martensite microstructures, and mechanical constraints reduce this critical size to ∼7nm, while significantly affecting the transformation temperatures. These results contribute to the understanding of martensitic transformation in nanocrystalline samples and of the fundamental limits of miniaturization of these alloys.

Environmental Deposition of Lead (Pb) in Chickens and Litter Samples Collected from Selected Areas of Bangladesh

The present work reported here was conducted to detect the deposition of lead (Pb) from the environment in chickens. The considered samples were muscles, liver, kidney, brain, bone and poultry litter. Twenty samples of each category were collected from different locations of major cities and districts of Bangladesh. The collected samples were digested by acid digestion procedures. The detection procedures were operated by Flame Atomic Absorption Spectrophotometric Analysis (FAAS) with Zeeman background correction by subtracting the mean value of blank sample. The analysis of variance of mean Pb concentration in different samples collected from different locations differed significantly (P<0.01).The highest concentration of lead (Pb) was found in bone (0.096±0.048mg/kg), followed by brain (0.085±0.044mg/kg), kidney (0.077±0.007mg/kg), liver (0.053±0.011mg/kg) and muscles (0.040±0.0211mg/kg). The natural accumulation of Pb was significantly (P<0.01) present in egg shell (0.251±0.032ml/kg) compared with to the yolk (0.089±0.010ml/kg) and albumen (0.066±0.003ml/kg). A significant level of (Pb) was also detected in poultry litter (0.580±0.067 mg/kg). Lead (Pb) levels in chickens meat and eggs in this study at present showed accepted level which is at present not in alarming stage but repeated consumption of lead (Pb) contaminated chicken meats and eggs may bring a serious public health hazard.

Accuracy of tablet splitting: Comparison study between hand splitting and tablet cutter

BackgroundTablet splitting is often used in pharmacy practice to adjust the administered doses. It is also used as a method of reducing medication costs. ObjectiveTo investigate the accuracy of tablet splitting by comparing hand splitting vs. a tablet cutter for a low dose drug tablet. MethodsSalbutamol tablets (4mg) were chosen as low dose tablets. A randomly selected equal number of tablets were split by hand and a tablet cutter, and the remaining tablets were kept whole. Weight variation and drug content were analysed for salbutamol in 0.1N HCl using a validated spectrophotometric method. The percentages by which each whole tablet’s or half-tablet’s drug content and weight difference from sample mean values were compared with USP specification ranges for drug content. The %RSD was also calculated in order to determine whether the drugs met USP specification for %RSD. The tablets and half tablets were scanned using electron microscopy to show any visual differences arising from splitting. Results27.5% of samples differed from sample mean values by a percentage that fell outside of USP specification for weight, of which 15% from the tablet cutter and 25% from those split by hand fell outside the specifications. All whole tablets and half tablets met the USP specifications for drug content but the variation of content between the two halves reached 21.3% of total content in case of hand splitting, and 7.13% only for the tablet cutter. The %RSDs for drug content and weight met the USP specification for whole salbutamol tablets and the half tablets which were split by tablet cutter. The halves which were split by hand fell outside the specification for %RSD (drug content=6.43%, weight=8.33%). The differences were visually clear in the electron microscope scans. ConclusionDrug content variation in half-tablets appeared to be attributable to weight variation occurring during the splitting process. This could have serious clinical consequences for medications with a narrow therapeutic-toxic range. On the basis of our results, we recommend to avoid tablet splitting whenever possible or the use of an accurate tablet splitting device when splitting cannot be avoided.

Relationship between post-exercise heart rate variability and skinfold thickness

This investigation aimed to determine if groupings based upon sum of skinfold thickness (SF) would reflect the differences in heart rate variability (HRV) measured for up to 30-minutes following maximal exercise, and to determine the extent in variation in post-exercise HRV that could be accounted for between the following independent variables: SF, body mass index (BMI) and maximal oxygen consumption (VO2max). SF and BMI measurements were performed on fifty-four men who completed maximal exercise testing to determine VO2max. HRV was evaluated for five-minutes before (Pre), at 0-5 minutes post- (Post1) and 25-30 minutes post-exercise (Post2), and analyzed by frequency domain [high frequency (HF) power, and HF to low frequency power ratio (LF:HF)). Two groups were formed based on being above or below the sample mean value of SF. HF and LF:HF were significantly higher and lower, respectively, at Pre and Post 2 in Group 1 compared to Group 2 (p < 0.05), which remained after controlling for VO2max and BMI. Furthermore, there was a significant trend toward baseline in post-exercise HRV in Group 1 (p < 0.05) but not in Group 2 (p > 0.05). In addition, SF was the only variable to significantly relate to the post-exercise HRV parameters (p < 0.05). The findings of this investigation suggest greater SF is related to a delayed return of HRV toward baseline from maximal exercise. The association between SF and HRV is independent of VO2max and BMI.

Assessment of the Residual Strength Thresholds of Composite Pressure Receptacles – Criteria for Hydraulic Load Cycle Testing

Abstract The current practice of periodic retesting of composite pressure receptacles primarily based on the hydraulic pressure test has to be evaluated as critical. This is justified by micro damages caused to the specimen by the test itself and by a lack of informative values. Thus, BAM Federal Institute of Materials Research and Testing uses a new validation approach in the case of retest periods of more than 5 years. It enables the description of the condition of a specific design type series based on destructive tests parallel to operation. With respect to this approach it is explained how the statistical evaluation of sample tests and their extrapolation to end of life or at least to the time of next retesting can be achieved. In addition, it is explained how the reliability limits may be linked to the size and pressure level of the respective composite pressure receptacle. The frame of this safety approach includes the influence of the maximum working pressure on the safety assessment. One topic of this approach is the introduction of the working diagram essential for safety assessments that allows graphical evaluation of load cycle strength by mean value, scatter and survival rate of samples as well as instruction how to use it. For this, it is explained how the number of filling cycles and the reduction of the respective hydraulic residual cycle strength interacts with the newly introduced value of specific filling sensitivity.

Survey on aflatoxin in beer sold in Spain and other European countries

Aflatoxins (B1, B2, G1 and G2) were surveyed in 417 beer samples purchased from the retail market in Spain (n=336), France (n=49), Portugal (n=15), Ireland (n=11) and Italy (n=6) in the period 2006-2012. In addition, 4 samples were acquired from Ghana and one from Israel. The analytical procedure was based on immunoaffinity clean-up and liquid chromatography with fluorescence detection. Aflatoxin was detected in 72.6% of the samples acquired in the Spanish market and in 182 out of 200 samples brewed in Spain with levels ranging from 0.08 to 36.12 ng/l for all four aflatoxins. The mean and median values of positive samples were estimated to be 3.51 and 2.07 ng/l, respectively, for samples acquired in Spain and 3.82 and 2.60 ng/l, respectively, for samples brewed in Spain. The mean and median values for the group of imported beers were 2.64 and 0.51 ng/l, respectively. Regarding the whole group of beers from European countries (417 samples), the incidence of positive samples was 64.7% with concentrations ranging from 0.07 to 45.18 ng/l for total aflatoxins with mean and median values of 3.47 and 1.82 ng/l, respectively. The overall median concentrations of aflatoxins in the samples of beers produced in Spain were 2.27-2.32 ng/l and for the whole group of European beers 0.43-0.62 ng/l (lower bound - upper bound). The median values obtained in this study for aflatoxin in beers consumed in Spain would result in an intake of approx. 97-112 pg/per capita/day, which represents a very small fraction (approx. 0.5% in a worst-case scenario) of the estimated average exposure to total aflatoxins.

Does Prior Specification Matter in Hotspot Identification and Before–After Road Safety Studies?

This study investigated the effects of prior assumptions in applications of full Bayes methods in road safety analysis. The effect of prior choice was evaluated in the accuracy of model parameters, hotspot identification, goodness of fit, and a treatment effectiveness index in before–after studies. Particular attention was devoted to conditions with a lack of data, which were referenced as the low-mean and small-sample problem. In this research, informative, semi-informative, and noninformative priors were determined on the basis of past published studies. A simulation framework was used to evaluate various scenarios of sample size and crash occurrence mean. Quasi-simulated data were generated on the basis of two empirical databases of divided and undivided rural highway segments in New York and Texas. Various sample mean values were obtained on the basis of time period (number of years) and classifying accidents in fatal–injury and total accidents. The outcomes under low-mean and small-sample conditions were found to be significantly biased. However, the introduction of informative priors can make observational before–after studies feasible when a few observations from treatment or comparison sites are used. Informative priors can help provide more accurate estimates of the effectiveness of the treatment. Finally, in accordance with previous works, the inverse dispersion parameter was significantly affected by prior specifications; nevertheless, regression parameters, goodness of fit, and hotspot identification were less sensitive to prior choices.

Analysis on Some Physical and Chemical Properties of Oreke Dolomite Deposit

The suitability of Oreke dolomite in Kwara State, Nigeria as a raw material for the manufacturing of refractories was investigated. The Oreke dolomite samples were mingled with feldspar, clay, and quartz to form a blend. The fifteen (15) Blend samples were moulded and analyzed for their chemical, physical and mechanical properties. The characterization was carried out in accordance with American Society of Testing and Material (ASTM). The blend samples were tested for various refractory properties such as bulk density, porosity, cold crushing strength, linear shrinkage, refractoriness and others like water absorption and compressive strength. The chemical composition of the Blend was determined, using X-Ray Fluorescence Spectrometer and the result shows that Silica is 60%, Alumina is 11.5%, Iron Oxide is 0.48%, Calcium Oxide is 10%, Magnesium is 6.4%, Alkali is 10.4%, and Loss of Ignition of the sample is 15.28%. The addition of 10%-12% quart contents with dolomite of 20%-25% contents complements the percentage of silica in the blend thereby improving the properties of the blend. The strength characterization shows that the Compressive Strength (mean value) of the blend samples is 5.65 N/m2 with respect firing temperature. The strength classification varies between medium to high and was found to satisfy the allowable standard values for the production of refractory wares.

Goodness-of-fit testing for accident models with low means

The modeling of relationships between motor vehicle crashes and underlying factors has been investigated for more than three decades. Recently, many highway safety studies have documented the use of negative binomial (NB) regression models. On rare occasions, the Poisson model may be the only alternative especially when crash sample mean is low. Pearson's X2 and the scaled deviance (G2) are two common test statistics that have been proposed as measures of goodness-of-fit (GOF) for Poisson or NB models. Unfortunately, transportation safety analysts often deal with crash data that are characterized by low sample mean values. Under such conditions, the traditional test statistics may not perform very well.This study has three objectives. The first objective is to examine all the traditional test statistics and compare their performance for the GOF of accident models subjected to low sample means. Secondly, this study proposes a new test statistic that is not dependent on the sample size for Poisson regression model, as opposed to the grouped G2 method. The proposed method is easy to use and does not require grouping data, which is time consuming and may not be feasible to use if the sample size is small. Moreover, the proposed method can be used for lower sample means than documented in previous studies. Thirdly, this study provides guidance on how and when to use appropriate test statistics for both Poisson and negative binomial (NB) regression models.

Sensitive determination of the peptide AP301 – A motif of TNF-α – From human plasma using HPLC–MS/MS

The AP301 peptide mimics the lectin-like domain of TNF-α. The synthetic peptide AP301 (molecular weight 1923.1amu) is composed of 17 amino acids and contains an intramolecular disulfide bond between the N-terminal and the C-terminal cysteine. AP301 interacts with the endothelial sodium channel (ENaC) and activates pulmonary liquid clearance both in vitro and in animal studies. Currently, AP301 is subject to clinical investigations for the treatment of pulmonary oedema. With HPLC–MS/MS on reversed phase chromatography a determination limit of 1ng AP301/mL human plasma can be achieved. The MS-ionisation was done with ESI positive. 50μL of human plasma was mixed with the internal standard (a stable isotope labelled AP301, with a total of 6 carbon 13) in acetonitrile for protein precipitation. After centrifugation a part of the clear supernatant was injected into HPLC–MS/MS. Validation was performed according to FDA-guideline in three batches [U.S. Department of Health and Human Services, Food and Drug Administration (FDA): Guidance for Industry, Bioanalytical Method Validation, May 2001]. By using a 6xC13 isotopically labelled internal standard good precision, accuracy and linearity can be gained. The inter-batch precision (CV) of the quality control samples in human plasma (conc. 2.50/20/240ng/mL) ranged from 5.54 to 10.15%. The inter-batch accuracy (with reference to the mean value) of the quality control samples in plasma ranged from 96.1% to 99.9%. The analyte was stable in human plasma over three freeze/thaw cycles, or for 4h at room temperature, or for at least 20weeks when stored at below −20°C. This method was used for quantifying AP301 after inhalative application in a phase I-study.