Parameters Standard Deviation Research Articles

Effects of OSA Surgery on Ophthalmological Microstructures.

Obstructive sleep apnea/hypopnea syndrome (OSA) could compromise oxygenation of the optic nerve and cause glaucomatous optic neuropathy; however, there were no studies to investigate the changes of visual function and retinal microstructures in OSA patients after upper airway surgery. We aim to assess the changes in the visual sensitivity and retinal fiber layer thickness in OSA patients before and after surgery. This prospective single-blind study enrolled patients with OSA from a tertiary academic medical center who had unsuccessful conservative therapy and then underwent surgery. The patients were referred for comprehensive ophthalmologic evaluation at baseline and 6 months after OSA surgery. The polysomnographic findings were collected pre- and postoperatively. Visual sensitivities on standard automated perimetry (SAP) were assessed. Peripapillary retinal nerve fiber layer (RNFL) thickness and macular layer (ML) thickness parameters were measured by spectral-domain optical coherence tomography (OCT). A total of 108 OSA patients were enrolled. Six months after surgery, the major parameters of polysomnography (PSG), mean deviation, and pattern standard deviation of SAP significantly improved in these OSA patients. Regarding the OCT parameters, thickness of ML in the nasal-outer, superior-inner, temporal-inner, inferior-inner, nasal-inner sectors, and total ML thickness significantly increased 6 months after upper airway surgery in the severe OSA group (apnea/hypopnea index ⩾30 per hour). The visual sensitivities on SAP, ML thickness on OCT, and oxygenation status on PSG significantly improved 6 months after upper airway surgery in patients with severe OSA. Upper airway surgery may ameliorate the microstructures of the retina in patients with severe OSA.

Transverse vibration analysis of a single-walled carbon nanotube under a random load action

The paper presents the dynamic model of a nanobeam loaded by a uniformly distributed random load, which is considered as a nonstationary stochastic process. The equation of motion is derived on the basis of non-local elasticity theory by using the Galerkin Finite Element Method. Probabilistic characteristics, in the form of time histories of the expected values and standard deviations of dynamic displacements, are computed applying Monte Carlo simulations and the Newmark method. The formulated algorithm is verified within the scope of the eigenvalue problem with a strict solution. A very good agreement is found. The influence of load standard deviation and non-local parameters on dynamic response is considered on the example of a clamped-clamped single-walled carbon nanotube (SWCNT). The obtained results show that random load perturbations should not be a priori neglected in dynamic analyses. The dispersion of displacements, caused by stochastic loads, can be greater than would be expected considering the level of deviations of applied loads.

Improved invasive weed optimization algorithm (IWO) based on chaos theory for optimal design of PID controller

Abstract Weed is a phenomenon which is looks for optimality and finds the best environment for life and quickly adapts itself to environmental conditions and resists changes. Considering these features, a powerful optimization algorithm is developed in this study. The invasive weed optimization algorithm (IWO) is a population-based evolutionary optimization method inspired by the behavior of weed colonies. In this paper, the IWO algorithm is based on chaos theory. Among parameters of weed optimization algorithm, standard deviation affects the performance of the algorithm significantly. Therefore, chaotic maps are used in the standard deviation parameter. Performance of the chaotic invasive weed development method is investigated on five benchmark functions, using logistic chaotic mapping. Additionally, the problem of setting the PID controller parameters for a DC motor using the proposed method is discussed. The statistical results on optimization problems show that the improved chaotic weed algorithm has gained fast convergence rate and high accuracy. Highlights Improved Invasive weed optimization Algorithm (IWO) based on Chaos theory. Improved setting the parameters of PID controller uses Chaotic IWO Algorithm.

Heart rate variability study in adult Nigerian subjects with sickle cell disease during vaso-occlusive crisis.

Autonomic nervous system (ANS) dysfunction assessed by abnormalities in heart rate variability (HRV) is thought to play a role in the pathophysiology of sickle cell disease (SCD). There is suggestion that changes in ANS may occur in SCD subjects during episodes of vaso-occlusive crises (VOC). The aim of this study was to evaluate the ANS by determining the HRV in patients with SCD during VOC. This was a cross-sectional observational study. HRV studies were carried out in 76 participants with SCD during episodes of VOC. Eighty-two SCD participants in steady state served as controls. Comparison of two independent groups with Student's t-test and Mann-Whitney's test, and multiple linear regressions were also carried out. Participants with SCD and VOC had significant reductions in the time-domain HRV parameters of standard deviation of RR intervals (45.8 [59.36] ms vs. 66.3 [129.2] ms, P = 0.0073) and root mean square of successive differences of RR intervals (48.3 [87.66] ms vs. 74.2 [174.5] ms, P = 0.0015). The frequency-domain HRV indices of low frequency (145.8 [81.62] ms2 vs. 157.5 [68.9] ms2, P = 0.1442) and high frequency (145.0 [118.40] ms2 vs. 146.3 [90.3] ms2, P = 0.3683) were similar between the two groups. Age and the heart rate were the major independent relations of the HRV parameters. Time-domain HRV parameters were impaired during crises in participants with SCD. This finding suggests further impairment of ANS activity in SCD patients during crises. Further studies are needed to clarify the prognostic implication of these findings.

Spatial externality and indeterminacy

We study conditions for existence and uniqueness of solutions in some space-structured economic models with long-distance interactions between locations. The solution of these models satisfies non local equations, in which the interactions are modeled by convolution terms. Using properties of the spectrum location obtained by studying the characteristic equation, we derive conditions for the existence and uniqueness of the solution. This enables us to characterize the degree of indeterminacy of the system being considered. We apply our methodology to a theoretical one-sector growth model with increasing returns, which takes into account technological interdependencies among countries that are modeled by spatial externalities. When symmetric interaction kernels are considered, we prove that conditions for which indeterminacy occurs are the same as the ones needed when no interactions are taken into account. For Gaussian kernels, we study the impact of the standard deviation parameter on the degree of indeterminacy. We prove that when some asymmetric kernels are considered, indeterminacy can occur with classical assumptions on supply and demand curves.

Correlation of peripapillary nerve fiber layer thickness with visual outcomes after decompression surgery in subclinical and clinical thyroid-related compressive optic neuropathy

PurposeTo assess the correlation of peripapillary retinal nerve fiber layer (PRNFL) thickness with visual recovery in compressive optic neuropathy (CON) in patients with thyroid eye disease (TED). MethodsTwenty-three eyes of 13 consecutive patients with TED-related CON were prospectively recruited. Assessment of PRNFL by means of spectral domain optical coherence tomography (SD-OCT), visual field (VF) parameters, color vision, and visual acuity in logMAR were compared before and 6 months after decompression surgery in the operated eye for each patient, which in ten cases included both eyes. Decompression surgery was performed as medial and inferior wall decompression sparing the orbital strut by the same surgeon. ResultsThere was a significant correlation between the preoperative PRNFL average thickness and postoperative improvement in visual acuity among all patients (P = 0.048). This correlation was found to be significant in clinically non-edematous optic neuropathy cases (P = 0.023) but not in edematous optic neuropathy (P = 0.23). There was significant correlation between PRNFL thickness and improvement of postoperative mean deviation (MD) and pattern standard deviation (PSD) parameters in VF studies and in color vision scores (P = 0.005, P = 0.02, P = 0.01, respectively). Average PRNFL thickness and quadrantal PRNFL were all significantly reduced after decompression surgery in all of the cases (P = 0.024). ConclusionsPRNFL thickness measured by SD-OCT is correlated with visual recovery after decompression surgery in TED-related CON. In eyes with severe VF defect (MD worse than −10 dB), the ones with higher preoperative PRNFL thicknesses (>65 μm) had more improvement in MD compared with those with thin PRNFL measures (<60 μm).

Direct determination by portable ED-XRF of mineral profile in cocoa powder samples.

The present study has exploited the rapidity of the analysis and the multi-elemental capability of the energy dispersive X- ray fluorescence (ED-XRF) technique for the mineral profile determination in cocoa powder. A fast, cheap and environmental sustainable method without reagent consumption or toxic waste generation has been proposed. The samples can be prepared in the form of pellets of 13 mm in diameter and 2-3 mm thickness. The different internal calibrations used by ED-XRF equipment did not provide accurate results when comparing the mineral profile with the concentration obtained by Inductively Couple Plasma Optical Emission Spectroscopy (ICP-OES) after microwave assisted digestion of samples. For direct ED-XRF analysis of the cocoa samples, an external calibration using as standards the cocoa samples diluted with sugar was prepared. The analytical parameters of Relative Standard Deviation and Limit of Detection for the determined elements are adequate to the concentration levels found in the samples.

Use of cepstral analysis for differentiating dysphonic from normal voices in children

ObjectivesCepstral measures have mainly been evaluated by studies conducted on dysphonic and healthy adults, and many of these studies have reported the advantages of using cepstral measures for the evaluation of dysphonia however there is a paucity regarding to the cepstral analyses' results in dysphonic children. In this present study, it is hypothesized that cepstral peak prominence (CPP) and some other parameters of cepstral analysis would differ in children with vocal nodules when compared with the same parameters of cepstral analysis of healthy children. MethodsIn this present study, totally 54 children aged between 5 years old to 12 years and 7 months participated. The study group consisted of 20 males and 7 females diagnosed with vocal nodules. The control group consisted of an equal number of age- and gender-matched healthy peers. Analysis of Dysphonia in Speech and Voice software (CSL Model 4500 equipment, Kay Elemetrics Group) was used to gather speech sample recordings according to the Consensus Auditory-Perceptual Evaluation of Voice/Turkish protocol. Cepstral measures of all the six CAPE-V sentences and sustained/a/sample were calculated. CPP, CPP fundamental frequency, CPP standard deviation (CPP SD), Low_high spectral ratio (L/H ratio), L/H ratio standard deviation parameters were taken into account when statistical analyses were completed. In addition to the descriptive statistics of ceptral measures for both groups, the differences between the study and control groups according to the gender were documented. ResultsIt was found that for both genders CPP and CPP SD values were significantly higher for the control group for vowel-weighted sample, all voiced-weighted sample, glottal attack-weighted sample, nasal weighted sample, and voiceless-weighted sample. In the vowel-weighted sample, CPP and CPP SD were significantly higher for the control group in males. In females, a difference was only observed on the CPP parameter for the same sentence. In terms of the CPP value of the sustained phonation sample, a significant difference was only detected for males, whereas no difference was detected for females. ConclusionsIn conclusion, present study found that cepstral analysis can be used to determine the difference between dysphonic and healthy voices of children and indicated that cepstral analysis should be a compulsory component of routine clinical voice evaluation of children. In addition, this present study indicates that of the cepstral analysis of sentences appear to be more sensitive to dysphonia than the analysis of vowel samples. In future studies, normative values of the CAPE-V/Turkish sentences and cutoff values for differentiating dysphonia from normal voice should be evaluated using a larger sample size.

Image fusion algorithm based on improved K-singular value decomposition and Hadamard measurement matrix

To solve the problem of high time and space complexity of traditional image fusion algorithms, this paper elaborates the framework of image fusion algorithm based on compressive sensing theory. A new image fusion algorithm based on improved K-singular value decomposition and Hadamard measurement matrix is proposed. This proposed algorithm only acts on a small amount of measurement data after compressive sensing sampling, which greatly reduces the number of pixels involved in the fusion and improves the time and space complexity of fusion. In the fusion experiments of full-color image with multispectral image, infrared image with visible light image, as well as multispectral image with full-color image, this proposed algorithm achieved good experimental results in the evaluation parameters of information entropy, standard deviation, average gradient, and mutual information.

Evaluation of raw wastewater characteristic and effluent quality in Kashan Wastewater Treatment Plant

Due to the lack of water in arid and semi-arid areas, reuse of wastewater can be a suitable way to compensate for water scarcity. Therefore, in this research, evaluation of the quality of wastewater of Kashan Treatment Plant to use for irrigation was studied. This descriptive cross-sectional study was conducted in 2016. pH, TSS, TDS, turbidity, COD, BOD5, Total Kjeldahl Nitrogen, Total Phosphorus, Total Coliform, fecal coliform, nematode eggs of inlet and outlet of wastewater treatment plant in Kashan were studied. Mean and standard deviation and wastewater quality parameters before and after treatment were tested with SPSS 22 (2014) software. The mean wastewater output of COD, BOD5, TSS, TDS and turbidity were respectively 86.6, 41.2, 11.11, 1095 mgL-1 and 17.5 NTU and the pH was equal to 7.22. Also, the average of Total Kjeldahl Nitrogen and phosphorus were 22.4 and 2.2 mgL-1 respectively. The mean of Total Coliform and fecal coliform were 225, 161 MPN / 100 ml respectively. In addition, no nematode eggs were found in final effluent. The results indicated that the treatment plants had a significant role in the control of microbial and organic pollution load of wastewater. Also, it is concluded that all parameters were in accordance with the standards of Iran\'s Department of Environment, so, it can be used for unrestricted irrigation.

Classification between natural and graphics images based on generalized Gaussian distributions

We propose a novel method for classifying photographic and computer-generated images based on generalized Gaussian distribution (GGD) modeling of subband coefficients. The estimated shape and standard deviation parameters of GGD within each resolution level, the ratio of the estimated shape parameters between different resolution levels, and the ratio of the estimated standard deviation parameters between different resolution levels are used as features for the classification.

Threading Dislocations in InGaAs/GaAs (001) Buffer Layers for Metamorphic High Electron Mobility Transistors

In order to evaluate various buffer layers for metamorphic devices, threading dislocation densities have been calculated for uniform composition In x Ga1−xAs device layers deposited on GaAs (001) substrates with an intermediate graded buffer layer using the LMD model, where LMD is the average length of misfit dislocations. On this basis, we compare the relative effectiveness of buffer layers with linear, exponential, and S-graded compositional profiles. In the case of a 2 μm thick buffer layer linear grading results in higher threading dislocation densities in the device layer compared to either exponential or S-grading. When exponential grading is used, lower threading dislocation densities are obtained with a smaller length constant. In the S-graded case, lower threading dislocation densities result when a smaller standard deviation parameter is used. As the buffer layer thickness is decreased from 2 μm to 0.1 μm all of the above effects are diminished, and the absolute threading dislocation densities increase.

The lognormal distribution explains the remarkable pattern documented by characteristic scores and scales in scientometrics

Abstract Characteristic scores and scales (CSS) – a well-established scientometric tool for the study of citation counts – have been used to document a striking phenomenon that characterizes citation distributions at high levels of aggregation: irrespective of scientific field and citation window empirical studies find a persistent pattern whereby about 70% of scientific papers belong to the class of poorly cited papers, about 21% belong to the class of fairly cited papers, 6% to that of remarkably cited papers and 3% to the class of outstandingly cited papers. This article aims to advance the understanding of this remarkable result by examining it in the context of the lognormal distribution, a popular model used to describe citation counts across scientific fields. The article shows that the application of the CSS method to lognormal distributions provides a very good fit to the 70–21–6–3% empirical pattern provided these distributions are characterized by a standard deviation parameter in the range of about 0.8–1.3. The CSS pattern is essentially explainable as an epiphenomenon of the lognormal functional form and, more generally, as a consequence of the skewness of science which is manifest in heavy-tailed citation distributions.

Model for threading dislocations in metamorphic tandem solar cells on GaAs (001) substrates

We present an approximate model for the threading dislocations in III–V heterostructures and have applied this model to study the defect behavior in metamorphic triple-junction solar cells. This model represents a new approach in which the coefficient for second-order threading dislocation annihilation and coalescence reactions is considered to be determined by the length of misfit dislocations, LMD, in the structure, and we therefore refer to it as the LMD model. On the basis of this model we have compared the average threading dislocation densities in the active layers of triple junction solar cells using linearly-graded buffers of varying thicknesses as well as S-graded (complementary error function) buffers with varying thicknesses and standard deviation parameters. We have shown that the threading dislocation densities in the active regions of metamorphic tandem solar cells depend not only on the thicknesses of the buffer layers but on their compositional grading profiles. The use of S-graded buffer layers instead of linear buffers resulted in lower threading dislocation densities. Moreover, the threading dislocation densities depended strongly on the standard deviation parameters used in the S-graded buffers, with smaller values providing lower threading dislocation densities.

Consumer Panel Size in Sensory Cosmetic Product Evaluation: A Pilot Study from a Statistical Point of View

Subjective evaluations are nowadays applied more commonly in cosmetic product assessment. They are used in quality control, product development steps and efficacy studies for claim support. Several studies have been published to determine the adequate number of panelists, but recommendations and guidelines dealing with this topic are rare in the cosmetic sector. The aim of the present pilot study was to recommend a suitable study plan and define the adequate consumer panel size for cosmetic consumer assessment. A questionnaire-based product evaluation study, with three different cosmetic products, was organized as a consumer test using a seven-point scale. As a last step, a specific statistical calculation was performed to define the minimum sample size. It showed that the minimum sample size, besides the obvious statistical parameters of standard deviation and confidence interval, also depends on age and gender of the panelists and product assessment item. Utilizing a CI of 95% a minimum of 60 panelists seems to be sufficient for home-use-test (HUT) with a given seven-point scale. A minimum of 101 panelists are shown to be sufficient utilizing a CI of 99%.

Population pharmacokinetics of continuous infusion of piperacillin in critically ill patients

Dosing recommendations for continuous infusion of piperacillin, a broad-spectrum beta-lactam antibiotic, are mainly guided by outputs from population pharmacokinetic models constructed with intermittent infusion data. However, the probability of target attainment in patients receiving piperacillin by continuous infusion may be overestimated when drug clearance estimates from population pharmacokinetic models based on intermittent infusion data are used, especially when higher doses (e.g. 16 g/24 h or more) are simulated. Therefore, the purpose of this study was to describe the population pharmacokinetics of piperacillin when infused continuously in critically ill patients. For this analysis, 270 plasma samples from 110 critically ill patients receiving piperacillin were available for population pharmacokinetic model building. A one-compartment model with linear clearance best described the concentration–time data. The mean ± standard deviation parameter estimates were 8.38 ± 9.91 L/h for drug clearance and 25.54 ± 3.65 L for volume of distribution. Creatinine clearance improved the model fit and was supported for inclusion as a covariate. In critically ill patients with renal clearance higher than 90 mL/min/1.73 m2, a high-dose continuous infusion of 24 g/24 h is insufficient to achieve adequate exposure (pharmacokinetic/pharmacodynamic target of 100% fT>4 x MIC) against susceptible Pseudomonas aerginosa isolates (MIC ≤16 mg/L). These findings suggest that merely increasing the dose of piperacillin, even with continuous infusion, may not always result in adequate piperacillin exposure. This should be confirmed by evaluating piperacillin target attainment rates in critically ill patients exhibiting high renal clearance.

Certificação ISO 14001: análise dos fatores relacionados à conscientização ambiental de colaboradores de uma indústria de papel da região centro-sul do Paraná

Environmental management systems certified by NBR ISO 14001:2004 emerge as alternatives for organizations to structure their environmental activities. The certification requires a primordial factor, which is environmental awareness. Given this, this research aims to identify and analyze the factors related to the environmental awareness of employees included in the ISO 14001 certification process, on a paper industry of the Center-South region of Paraná. In order to achieve the proposed objectives, we applied a quantitative approach by the application of questionnaires to the employees of the industry researched. The treatment of the data occurred by means of descriptive statistics, being used the parameters of average, standard deviation and coefficient of variation, as well as the factor analysis for grouping and analysis of factors that showed more awareness and testing validation of the scale. As a result, they identified the factors related to environmental awareness, which were passed on to the employees by training, internal disclosures and other mechanisms that helped the company to achieve a satisfactory level of awareness. However, there was an opportunity for the paper industry to enhance awareness to waste management, wastewater and chemicals, since not all employees know the destination and the treatment of waste at the end of process.

Fuzzy cerebellar model articulation controller network optimization via self-adaptive global best harmony search algorithm

Fuzzy cerebellar model articulation controller (FCMAC) networks with excellent nonlinear appropriation ability and simple implementation are used to solve complex uncertainties problems in engineering applications. Both online and off-line learning algorithm of FCMAC networks usually applies the gradient-descent-type methods. However, such gradient-descent methods lead to the high possibility to converging into local minima. To cope with the local minimum problem, this paper alternatively proposes to apply harmony search algorithm to find optimal network parameters, so as to achieve better performances of FCMAC. The harmony search algorithm optimizes not only FCMAC network’s weight variables, but also optimizes network receptive field’s center position and standard deviation parameters. In order to obtain an optimal network, the weight values, center positions, and standard deviations are transformed to three data strings that can be processed by harmony search algorithm. In particular, the self-adaptive global best harmony search algorithm (SGHS) is used to search optimal parameter combinations of FCMAC within solution domains. The network’s performances are verified by approximating six nonlinear formulae. In order to compare the performances of the FCMAC networks optimized by the SGHS algorithm, a back-propagation trained network and another harmony search variant optimized networks are also tested in this work. The experimental results show that the networks optimized by SGHS perform the faster convergence speed and better accuracy.

Method Development and Validation for Related Impurities of Efavirenz by RP-HPLC Method

A simple, specific, validated reverse phase high performance liquid chromatographic method has been developed for the quantification of related impurities of Efavirenz in bulk drug substance. In this method impurities are quantified successfully at 0.2% quantification threshold. This method utilizes high purity silica based RP-C18 column i.e Inertsil-ODS 3 V (250 × 4.6 mm × 5 μm) with which efficient separation and resolution was achieved at a temperature of 45°C with a flow rate of 1.5 ml/min. 0.1% o-Phoshoric acid and Acetonitrile in the ratio of 20:80 v/v was employed as a mobile phase and samples were scanned at a wavelength of 245 nm. Validation of the method was successfully established by performing various validation parameters such as specificity, precision, linearity, accuracy, LOD, LOQ, robustness, ruggedness according to ICH guidelines. A strong linear relation exists over the range of 20 to 120% specification level with a correlation coefficient value of 0.999. The method was sufficiently accurate, precise, robust and rugged with a good recovery, acceptable standard deviation and system suitability parameters within the stipulated limits. The method sensitivity was accomplished by LOD & LOQ. This method can be successfully employed for the routine in process quality control and for the quantification of impurities in bulk drug substance.

Is there a systematic relationship between random parameters and process heuristics?

•Inclusion of decision process heterogeneity together with preference heterogeneity.•Mean and standard deviation parameters conditioned by process strategies.•Value learning process strategy.•Links between process rules and random parameters under standard LPAA.•Influence on the estimates' distribution and willingness to pay.