Nuisance Factor Research Articles

Improved quantification of livestock associated odorous volatile organic compounds in a standard flow-through system using solid-phase microextraction and gas chromatography–mass spectrometry

Aerial emissions of odorous volatile organic compounds (VOCs) are an important nuisance factor from livestock production systems. Reliable air sampling and analysis methods are needed to develop and test odor mitigation technologies. Quantification of VOCs responsible for livestock odor remains an analytical challenge due to physicochemical properties of VOCs and the requirement for low detection thresholds. A new air sampling and analysis method was developed for testing of odor/VOCs mitigation in simulated livestock emissions system. A flow-through standard gas generating system simulating odorous VOCs in livestock barn emissions was built on laboratory scale and tested to continuously generate ten odorous VOCs commonly defining livestock odor. Standard VOCs included sulfur VOCs (S-VOCs), volatile fatty acids (VFAs), and p-cresol. Solid-phase microextraction (SPME) was optimized for sampling of diluted odorous gas mixtures in the moving air followed by gas chromatography–mass spectrometry (GC-MS) analysis. CAR/PDMS 85μm fiber was shown to have the best sensitivity for the target odorous VOCs. A practical 5-min sampling time was selected to ensure optimal extraction of VFAs and p-cresol, as well as minimum displacement of S-VOCs. Method detection limits ranged from 0.39 to 2.64ppbv for S-VOCs, 0.23 to 0.77ppbv for VFAs, and 0.31ppbv for p-cresol. The method developed was applied to quantify VOCs and odorous VOC mitigation with UV light treatment. The measured concentrations ranged from 20.1 to 815ppbv for S-VOCs, 10.3 to 315ppbv for VFAs, and 4.73 to 417ppbv for p-cresol. Relative standard deviations between replicates ranged from 0.67% to 12.9%, 0.50% to 11.4%, 0.83% to 5.14% for S-VOCs, VFAs, and p-cresol, respectively. This research shows that a simple manual SPME sampler could be used successfully for quantification of important classes of odorous VOCs at concentrations relevant for real aerial emissions from livestock operations.

Effects of scanner acoustic noise on intrinsic brain activity during auditory stimulation

Although the effects of scanner background noise (SBN) during functional magnetic resonance imaging (fMRI) have been extensively investigated for the brain regions involved in auditory processing, its impact on other types of intrinsic brain activity has largely been neglected. The present study evaluated the influence of SBN on a number of intrinsic connectivity networks (ICNs) during auditory stimulation by comparing the results obtained using sparse temporal acquisition (STA) with those using continuous acquisition (CA). Fourteen healthy subjects were presented with classical music pieces in a block paradigm during two sessions of STA and CA. A volume-matched CA dataset (CAm) was generated by subsampling the CA dataset to temporally match it with the STA data. Independent component analysis was performed on the concatenated STA-CAm datasets, and voxel data, time courses, power spectra, and functional connectivity were compared. The ICA revealed 19 ICNs; the auditory, default mode, salience, and frontoparietal networks showed greater activity in the STA. The spectral peaks in 17 networks corresponded to the stimulation cycles in the STA, while only five networks displayed this correspondence in the CA. The dorsal default mode and salience networks exhibited stronger correlations with the stimulus waveform in the STA. SBN appeared to influence not only the areas of auditory response but also the majority of other ICNs, including attention and sensory networks. Therefore, SBN should be regarded as a serious nuisance factor during fMRI studies investigating intrinsic brain activity under external stimulation or task loads.

A gradient in cortical pathology in multiple sclerosis by in vivo quantitative 7 T imaging.

We used a surface-based analysis of T2* relaxation rates at 7 T magnetic resonance imaging, which allows sampling quantitative T2* throughout the cortical width, to map in vivo the spatial distribution of intracortical pathology in multiple sclerosis. Ultra-high resolution quantitative T2* maps were obtained in 10 subjects with clinically isolated syndrome/early multiple sclerosis (≤ 3 years disease duration), 18 subjects with relapsing-remitting multiple sclerosis (≥ 4 years disease duration), 13 subjects with secondary progressive multiple sclerosis, and in 17 age-matched healthy controls. Quantitative T2* maps were registered to anatomical cortical surfaces for sampling T2* at 25%, 50% and 75% depth from the pial surface. Differences in laminar quantitative T2* between each patient group and controls were assessed using general linear model (P < 0.05 corrected for multiple comparisons). In all 41 multiple sclerosis cases, we tested for associations between laminar quantitative T2*, neurological disability, Multiple Sclerosis Severity Score, cortical thickness, and white matter lesions. In patients, we measured, T2* in intracortical lesions and in the intracortical portion of leukocortical lesions visually detected on 7 T scans. Cortical lesional T2* was compared with patients' normal-appearing cortical grey matter T2* (paired t-test) and with mean cortical T2* in controls (linear regression using age as nuisance factor). Subjects with multiple sclerosis exhibited relative to controls, independent from cortical thickness, significantly increased T2*, consistent with cortical myelin and iron loss. In early disease, T2* changes were focal and mainly confined at 25% depth, and in cortical sulci. In later disease stages T2* changes involved deeper cortical laminae, multiple cortical areas and gyri. In patients, T2* in intracortical and leukocortical lesions was increased compared with normal-appearing cortical grey matter (P < 10(-10) and P < 10(-7)), and mean cortical T2* in controls (P < 10(-5) and P < 10(-6)). In secondary progressive multiple sclerosis, T2* in normal-appearing cortical grey matter was significantly increased relative to controls (P < 0.001). Laminar T2* changes may, thus, result from cortical pathology within and outside focal cortical lesions. Neurological disability and Multiple Sclerosis Severity Score correlated each with the degree of laminar quantitative T2* changes, independently from white matter lesions, the greatest association being at 25% depth, while they did not correlate with cortical thickness and volume. These findings demonstrate a gradient in the expression of cortical pathology throughout stages of multiple sclerosis, which was associated with worse disability and provides in vivo evidence for the existence of a cortical pathological process driven from the pial surface.

Sciarid fungus-gnats as nuisance factor in Pinus timber yards

Some Sciaridae species are considered as cosmopolitan pests in greenhouses and mushrooms farms. The potential harm of these insects involves plant tissue damage and transmission of pathogens to the seedlings. Recently, large sciarid masses were found infesting wood log stocking of processing industries and turned to be a severe nuisance factor and a public health issue. The Sciarid specimens from infested areas were identified belonging to the genus Bradysia Winnertz, 1867. These species certainly do not correspond to pests, but to species that are possibly associated to microenvironments generated by the fungi on the wood bark.

Modeling bi-modality improves characterization of cell cycle on gene expression in single cells.

Advances in high-throughput, single cell gene expression are allowing interrogation of cell heterogeneity. However, there is concern that the cell cycle phase of a cell might bias characterizations of gene expression at the single-cell level. We assess the effect of cell cycle phase on gene expression in single cells by measuring 333 genes in 930 cells across three phases and three cell lines. We determine each cell's phase non-invasively without chemical arrest and use it as a covariate in tests of differential expression. We observe bi-modal gene expression, a previously-described phenomenon, wherein the expression of otherwise abundant genes is either strongly positive, or undetectable within individual cells. This bi-modality is likely both biologically and technically driven. Irrespective of its source, we show that it should be modeled to draw accurate inferences from single cell expression experiments. To this end, we propose a semi-continuous modeling framework based on the generalized linear model, and use it to characterize genes with consistent cell cycle effects across three cell lines. Our new computational framework improves the detection of previously characterized cell-cycle genes compared to approaches that do not account for the bi-modality of single-cell data. We use our semi-continuous modelling framework to estimate single cell gene co-expression networks. These networks suggest that in addition to having phase-dependent shifts in expression (when averaged over many cells), some, but not all, canonical cell cycle genes tend to be co-expressed in groups in single cells. We estimate the amount of single cell expression variability attributable to the cell cycle. We find that the cell cycle explains only 5%–17% of expression variability, suggesting that the cell cycle will not tend to be a large nuisance factor in analysis of the single cell transcriptome.

A study on education quality using the Taguchi method

This article introduces a case study using the Taguchi method to improve education quality. Developed by Taguchi Genichi, this method has its strength in finding the control factor that is robust against other nuisance factors. Finding the condition for such a control factor has an effect of reducing the dispersion of the results. Various forms of noise exist in university classrooms. Multiple factors such as the psychology of the students and the instructor can have an effect on education quality but are often neglected in current teaching standards. The Taguchi method, which has successfully been implemented in manufacturing, can also be applied in education settings to provide better lectures (of higher quality) to students (customers). Hence this article introduces a methodology to improve lecture quality by using the Taguchi method in education settings and discusses a case study for it. The study analyses the factors that affect lecture quality and distinguishes between the control factor that is controllable by the instructor and the nuisance factor that is not controllable but is important in terms of lecture quality. Then the experiment is conducted as guided by Taguchi's experimental design, and after discussion of the results the optimal lecture method is suggested. The difficulty with the approach lies in defining and measuring lecture quality and conducting the experiment under settings with various factors. A suggestion regarding this difficulty is discussed. However, this difficulty still raises a question. The contribution of this article is the discussion of the possibility of implementing the Taguchi method – traditionally used in manufacturing – in university lectures, which can be considered a form of service provided to the students, and offering Taguchi's optimum result as a solution to a practical problem.

Learning time-varying categories

Many kinds of objects and events in our world have a strongly time-dependent quality. However, most theories about concepts and categories either are insensitive to variation over time or treat it as a nuisance factor that produces irrational order effects during learning. In this article, we present two category learning experiments in which we explored peoples' ability to learn categories whose structure is strongly time-dependent. We suggest that order effects in categorization may in part reflect a sensitivity to changing environments, and that understanding dynamically changing concepts is an important part of developing a full account of human categorization.

Analysis of small-sample clinical genomics studies using multi-parameter shrinkage: application to high-throughput RNA interference screening

High-throughput (HT) RNA interference (RNAi) screens are increasingly used for reverse genetics and drug discovery. These experiments are laborious and costly, hence sample sizes are often very small. Powerful statistical techniques to detect siRNAs that potentially enhance treatment are currently lacking, because they do not optimally use the amount of data in the other dimension, the feature dimension.We introduce ShrinkHT, a Bayesian method for shrinking multiple parameters in a statistical model, where 'shrinkage' refers to borrowing information across features. ShrinkHT is very flexible in fitting the effect size distribution for the main parameter of interest, thereby accommodating skewness that naturally occurs when siRNAs are compared with controls. In addition, it naturally down-weights the impact of nuisance parameters (e.g. assay-specific effects) when these tend to have little effects across siRNAs. We show that these properties lead to better ROC-curves than with the popular limma software. Moreover, in a 3 + 3 treatment vs control experiment with 'assay' as an additional nuisance factor, ShrinkHT is able to detect three (out of 960) significant siRNAs with stronger enhancement effects than the positive control. These were not detected by limma. In the context of gene-targeted (conjugate) treatment, these are interesting candidates for further research.

Problems with single interest scales: Implications of the general factor

The presence of the general factor in interest and self-efficacy assessment and its meaning are reviewed. The general factor is found in all interest and self-efficacy assessment and has been viewed as (a) a nuisance factor with little effect on assessment, (b) a variable having substantive meaning and thus worthy of including in interpretation, and (c) as systematic bias that distorts the interpretation of the meaning of assessments. The premise of this article is that each interpretation is correct but only depending upon the context of the assessment. The main implication is that narrow single content interest scales are very subject to contaminating effects of the general factor making interpretation very difficult. Methods of correcting this contamination are presented.

Willingness to Pay for Mosquito Control: How Important Is West Nile Virus Risk Compared to the Nuisance of Mosquitoes?

Public health programs that control mosquitoes and other disease vectors have the added benefit of reducing residents' exposure to pest insects. We surveyed homeowners in Madison, Wisconsin, and used an economic valuation method, stated-choice experiments, to measure willingness to pay (WTP) for control of West Nile virus (WNV)-transmitting and nuisance mosquitoes under current and increased levels of WNV risk. Under current WNV risk levels (approximately 1 in 250,000), the average Madison survey respondent was not willing to pay for programs that targeted West Nile-transmitting mosquitoes only (WTP=-$21, 95% [CI -$63, $20]), while WTP for a reduction in nuisance mosquitoes was substantial (WTP=$147, 95% [CI $109, $186]). As the risk of WNV was increased, WTP for control of disease-carrying mosquitoes also increased (WTP=$158; 95% CI [$111, $206] at the highest risk level), but WTP for nuisance control remained high (WTP=$108; 95% CI [$78, $138]). Among homeowners in our sample, the "nuisance factor" was more important than the "disease factor" in terms of respondents' demand for mosquito control.

Placebo effect in patients with irritable bowel syndrome

The placebo effect has evolved from being considered a nuisance factor in clinical research to a hot topic of scientific investigation. New research findings show that a placebo has real psychobiological and biological effects that are attributable to the overall therapeutic context. Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal tract that shows a significant placebo response of around 40–50% among different clinical trials.A positive patient-practitioner relationship can enhance the placebo effect in IBS patients.Emerging literature using functional brain imaging has started to document the neuronal changes associated with the placebo phenomenon in IBS patients, showing aberrant neural network during visceral placebo analgesia when compared to controls. Further promotion and integration of laboratory and clinical research are encouraged to advance the understanding of placebo mechanisms in IBS patients.

Evaluation of Tag Entanglement as a Factor in Harmonic Radar Studies of Insect Dispersal

The observation of insects and other small organisms entangled in the habitat after the addition of vertical or trailing electronic tags to their body has generated concerns on the suitability of harmonic radars to track the dispersal of insects. This study compared the walking behavior of adult Colorado potato beetle (Leptinotarsa decemlineata (Say) Chrysomelidae), plum curculio (Conotrachelus nenuphar (Herbst) Curculionidae), and western corn rootworm (Diabrotica virgifera virgifera (LeConte) Chrysomelidae) with and without vertical and or trailing tags in field plots or arenas. The frequency of the larger Colorado potato beetles crossing bare ground or grassy plots was unaffected by the presence of an 8 cm trailing harmonic radar tag. However, plum curculios and western corn rootworms, were either unable to walk with a 4 cm trailing tag (plum curculio) or displayed a reduced ability to successfully cross a bare ground arena. Our results revealed the significant impact of vegetation on successful insect dispersal, whether tagged or not. The vertical movement of these insects on stems, stalks, and tubes was also unaffected by the presence of vertical tags. Trailing tags had a significant negative effect on the vertical movement of the western corn rootworm. Results show that harmonic radar technology is a suitable method for studying the walking paths of the three insects with appropriate tag type and size. The nuisance factor generated by appropriately sized tags was small relative to that of vegetation.

Parameter Setting for Rod Push Production Process on Multiple Responses : A Case Study in Motorcycle Parts Factory

The aim of this research is to study appropriate setting of parameters in the production process ofRod Push which affect quality characteristics such as diameter and surface roughness. Cycle time is alsoconsidered. The problem was done at a study plant and it was found that the actual process capability index(Cpk) of two quality characteristics was less than the manufacturer’s standard of 1.33. Central composite designwas used to examine Rod Push produced by CNC with 5 controllable process factors including three factorsfrom rough-cutting process (spindle speed, feed rate, and depth of cut) and two factors from finish-cuttingprocess (spindle speed and feed rate). The nuisance factor of CNC was cutting tool wear. After collectingall data, the appropriate setting was investigated. The new results indicated that the new condition yieldedthe better process performance index and shorter cycle time. Keywords: DOE; Central Composite Design; Rod Push Process; CNC Turning Machine

Epistasis: Obstacle or Advantage for Mapping Complex Traits?

Identification of genetic loci in complex traits has focused largely on one-dimensional genome scans to search for associations between single markers and the phenotype. There is mounting evidence that locus interactions, or epistasis, are a crucial component of the genetic architecture of biologically relevant traits. However, epistasis is often viewed as a nuisance factor that reduces power for locus detection. Counter to expectations, recent work shows that fitting full models, instead of testing marker main effect and interaction components separately, in exhaustive multi-locus genome scans can have higher power to detect loci when epistasis is present than single-locus scans, and improvement that comes despite a much larger multiple testing alpha-adjustment in such searches. We demonstrate, both theoretically and via simulation, that the expected power to detect loci when fitting full models is often larger when these loci act epistatically than when they act additively. Additionally, we show that the power for single locus detection may be improved in cases of epistasis compared to the additive model. Our exploration of a two step model selection procedure shows that identifying the true model is difficult. However, this difficulty is certainly not exacerbated by the presence of epistasis, on the contrary, in some cases the presence of epistasis can aid in model selection. The impact of allele frequencies on both power and model selection is dramatic.

Multiresponse optimization with consideration of probabilistic covariates

AbstractIn many complex experiments, nuisance factor may have large effects that must be accounted for. Covariates are one of the most important kinds of nuisance factors that can be measured but cannot be controlled within the experimental runs. In this paper a novel approach is proposed, based on goal programming, to find the best combination of factors so as to optimize multiresponse‐multicovariate surfaces with consideration of location and dispersion effects. Furthermore, it is supposed that several covariates considered in the experiment have probability distributions of known form. One objective is to find the most probable values of each covariate. For this purpose, a multiobjective mathematical optimization model is proposed and its efficacy is demonstrated by two numerical examples. Copyright © 2010 John Wiley &amp; Sons, Ltd.

What a nuisance: Controlling for negative affectivity versus personality in hospitality stress research

One stream of dispositional stress research examines the role negative affectivity (NA) plays in the stressor–strain relationship, with most research showing NA is a nuisance factor – spuriously inflating stressor–strain associations. Personality is not unidimensional, though, and measuring a single construct may be inadequate. This study reexamines the impact NA has in the hospitality context, and the role played by NA when all five global dimensions of personality – the Big Five – are included. Variance reduction rates revealed that (a) NA is a “nuisance factor,” and (b) the Big Five have differential effects – either inflationary or deflationary – depending upon the stressor–strain relationship examined.

Adjusting for Founder Relatedness in a Linkage Analysis Using Prior Information

In genetic linkage studies, while the pedigrees are generally known, background relatedness between the founding individuals, assumed by definition to be unrelated, can seriously affect the results of the analysis. Likelihood approaches to relationship estimation from genetic marker data can all be expressed in terms of finding the most likely pedigree connecting the individuals of interest. When the true relationship is the main focus, the set of all possible alternative pedigrees can be too large to consider. However, prior information is often available which, when incorporated in a formal and structured way, can restrict this set to a manageable size thus enabling the calculation of a posterior distribution from which inferences can be drawn. Here, the unknown relationships are more of a nuisance factor than of interest in their own right, so the focus is on adjusting the results of the analysis rather than on direct estimation. In this paper, we show how prior information on founder relationships can be exploited in some applications to generate a set of candidate extended pedigrees. We then weight the relevant pedigree-specific likelihoods by their posterior probabilities to adjust the lod score statistics.

Trend‐Free Nested Balanced Incomplete Block Designs and Designs for Diallel Cross Experiments

Abstract: Nested balanced incomplete block (NBIB) designs are useful when the experiments are conducted to deal with experimental situations when one nuisance factor is nested within the blocking factor. Similar to block designs, trend may exist in experimental units within sub‐blocks or within blocks in NBIB designs over time or space. A necessary and sufficient condition, for a nested block design to be trend‐free at sub‐block level, is derived. Families and catalogues of NBIB designs that can be converted into trend‐free NBIB designs at sub‐block and block levels have been obtained. A NBIB design with sub‐block size 2 has a one to one correspondence with designs for diallel crosses experiments. Therefore, optimal block designs for dialled cross experiments have been identified to check if these can be converted in to trend‐free optimal block designs for diallel cross experiments. A catalogue of such designs is also obtained. Trend‐free design is illustrated with example for a NBIB design and a design for diallel crosses experiments. AMS (2000) Subject Classification: 62K05, 62K10.

The mosquito, the elephant and the House of Lords Water Management Inquiry

In 2005, sensing that there was growing public interest and concern about water, the House of Lords Science and Technology Committee decided to hold an Inquiry into Water Management in England and Wales. The nature of such inquiries is that they seek to elicit evidence of the latest thinking, experience and opinion from a wide cross-section of persons and sources, and to weigh such evidence in an impartial manner in order to make recommendations to Government with regard to policies and actions. In this paper we examine three of the issues that provide communication spaces for the sense-making of policy, science and technological thinking around the subject of water management: levels of affordability, debt and disconnections; the appropriateness or otherwise of defined 'economic' or 'sustainable' levels of leakage; and burgeoning housing development and associated projections of water demand. Although in policy matters the House of Lords Science and Technology Committee has limited formal powers, it can exercise a significant nuisance factor on Government, much like a mosquito on an elephant.

Medical Errors Arising from Outsourcing Laboratory and Radiology Services

Objective Document errors and the nuisance factor inherent in the informational exchange that occurs with the outsourcing of laboratory and radiology examinations. Methods Three infectious diseases physicians at a tertiary care hospital recorded problems involving data transmitted by telephone or fax from outsource providers for 4 months. This included in- and outpatients, and those in transition from one status to another. Results Outsourcing laboratory and radiology examinations of insured outpatients is a common practice. Insurance companies determine which healthcare facility performs these tests based on contractual agreements with outsource providers. This leads to confusion and frustration for the doctor and patient alike, and occasionally, to medical error. Conclusions The exchange of patient data involved in outsourcing is subject to systemic errors that do not allow of easy solution.