Selective Disproportionation Research Articles

Person Misfit and Person Reliability in Rating Scale Measures: The Role of Response Styles

ABSTRACT Person misfit and person reliability indices in item response theory (IRT) can play an important role in evaluating the validity of a test or survey instrument at the respondent level. Prior empirical comparisons of these indices have been applied to binary item response data and suggest that the two types of indices return very similar results. In this paper, however, we demonstrate an important applied distinction between these methods when applied to polytomously-scored rating scale items, namely their varying sensitivities to response style tendencies. Using several empirical datasets, we illustrate settings in which these indices are in one case highly correlated and in two other cases weakly correlated. In the datasets showing a weak correlation between indices, the primary distinction appears due to the effects of response style behavior, whereby respondents whose response styles are less common (e.g. a disproportionate selection of the midpoint response) are found to misfit using Drasgow et al’s person misfit index, but often show high levels of reliability from a person reliability perspective; just the opposite frequently occurs for respondents that over-select the rating scale extremes. It is suggested that person misfit reporting should be supplemented with an evaluation of person reliability to best understand the validity of measurement at the respondent level when using IRT models with rating scale measures.

Simulating self-selection in public management research: implications from caseworker discretion in the child welfare system

PurposeThe purpose of this study was to measure the bias on a binary option's effect estimate that appeared in the types of questions asked and in the placement changes of public service users.Design/methodology/approachThe author designed Monte Carlo simulations with the analytical strategy of latent trait theory leveraging a probability of care-placement change. The author used difference-in-difference (DID) method to estimate the effects of care settings.FindingsThe author explained the extent of discrepancy between the estimates and the true values of care service effects in changes across time. The time trend of in-home care for the combined effect of in-home care, general maturity, and other environmental factors was estimated in a biased manner, while the bias for the estimate of the incremental effect for foster care could be negligible.Research limitations/implicationsThis study was designed based on individual child-unit only. Therefore, higher-level units, such as care setting or cluster, county, and state, should be considered for the simulation model.Social implicationsThis study contributed to illuminating an overlooked facet in causal inferences that embrace disproportionate selection biases that appear in categorical data scales in public management research.Originality/valueTo model the nuance of a disproportionate self-selection problem, the author constructed a scenario surrounding a caseworker's judgment of care placement in the child welfare system and investigated potential bias of the caseworker's discretion. The unfolding model has not been widely used in public management research, but it can be usefully leveraged for the estimation of a decision probability.

Intrasynovial triamcinolone treatment is not associated with incidence of acute laminitis.

Intrasynovial corticosteroid injections are commonly used in the treatment of equine orthopaedic disease, but corticosteroid administration is widely considered a risk factor for the development of laminitis. Despite a list of putative mechanisms and a number of case reports of steroid-induced laminitis, no case-control or cohort studies investigating the association between use of intrasynovial corticosteroids and acute laminitis have been published. To quantify the risk of laminitis posed by intrasynovial triamcinolone acetonide (TA) administration in a mixed population of horses. Retrospective observational cohort study. Clinical records of horses registered with one large UK equine practice were reviewed retrospectively to identify all horses receiving intrasynovial TA treatment between 1 January 2007 and 31 December 2017. A total of 1510 horses were selected and records investigated for incidence of laminitis over a 4-month period following treatment. For each TA-treated horse, an untreated horse, individually matched by age, sex, date of treatment and client type, was selected from the clinical records. Untreated horses were then investigated for laminitis over the same 4-month period. Data were analysed in a 2×2 contingency table using Fisher's exact test. A total of 489 horses were lost to follow-up and 55 horses were excluded, leaving 966 treated and matched, untreated horses. The incidence of laminitis over the 4-month study period in both groups was identical: 3/966 horses (0.31%) (95% C.I. [0.08%, 0.91%]), equivalent to 0.93 cases per 100 horses per year (P>.9). Retrospective study; large proportion (489/1510) of horses lost to follow-up; large proportion of study population were racehorses; selection method resulted in disproportionate selection of horses born before 2013; similar incidence between groups may reflect existing risk-based selection by clinicians. intrasynovial triamcinolone acetonide administration does not increase the risk of laminitis in this study population.

Juggling options: Manipulation ease determines primate optimal fruit‐size choice

AbstractOptimal foraging theory predicts that animals will seek simultaneously to minimize food processing time and maximize energetic gain. To test this hypothesis, we evaluated whether a specialist seed‐predator primate forages optimally when choosing among variable‐sized thick‐husked fruits. Our objects of study were the golden‐backed uacari (Cacajao ouakary, Pitheciidae) and single‐seeded pods of the macucu tree (Aldina latifolia, Fabaceae). We predict that golden‐backed uacari will consume fruits of the size class that requires the least time to obtain, handle, and ingest. We used scan sampling, ad libitum to record feeding observations, and measured fruits, their penetrability, and the size of taxidermized C. ouakary hands. To test whether uacaris selected for optimal characteristics, we compared 8 metrics from 75 eaten and 105 uneaten seeds/fruits collected. Uacaris selected fruits of medium size and weight disproportionately to their abundance. Processing large fruits took six times longer than did medium‐sized fruits, but seeds were only four times as large, that is, for energetic yield per unit time, thus choosing medium‐sized pods was optimal. Disproportionate selection by C. ouakary of fruits of medium size and mass in relation to their abundance suggests active sub‐sampling of the available weight–size continuum. This selectivity probably maximizes trade‐offs between the energy derived from a seed, and time and energy expended in processing fruit to access this, so following optimal foraging theory predictions. The greater time spent processing large pods is attributed to difficulties manipulating objects five to seven times the size of the animal's palm and one‐sixth its own body weight.

Phylodynamics of Influenza A/H1N1pdm09 in India Reveals Circulation Patterns and Increased Selection for Clade 6b Residues and Other High Mortality Mutants.

The clinical severity and observed case fatality ratio of influenza A/H1N1pdm09 in India, particularly in 2015 and 2017 far exceeds current global estimates. Reasons for these frequent and severe epidemic waves remain unclear. We used Bayesian phylodynamic methods to uncover possible genetic explanations for this, while also identifying the transmission dynamics of A/H1N1pdm09 between 2009 and 2017 to inform future public health interventions. We reveal a disproportionate selection at haemagglutinin residue positions associated with increased morbidity and mortality in India such as position 222 and clade 6B characteristic residues, relative to equivalent isolates circulating globally. We also identify for the first time, increased selection at position 186 as potentially explaining the severity of recent A/H1N1pdm09 epidemics in India. We reveal national routes of A/H1N1pdm09 transmission, identifying Maharashtra as the most important state for the spread throughout India, while quantifying climactic, ecological, and transport factors as drivers of within-country transmission. Together these results have important implications for future A/H1N1pdm09 surveillance and control within India, but also for epidemic and pandemic risk prediction around the world.

The Effect of Viscosity on the Diffusion and Termination Reaction of Organic Radical Pairs.

The effect of viscosity on the diffusion efficiency (Fdif ) of an organic radical pair in a solvent cage and the termination mechanism, that is, the selectivity of disproportionation (Disp) and combination (Comb) of the geminated caged radical pair and the diffused radicals encountered, were investigated quantitatively by following the photolysis of dimethyl 2,2'-azobis(2-methylpropionate) (V-601) in the absence and presence of PhSD. Fdif and Disp/Comb selectivity outside the cage [Disp(dif) /Comb(dif) ] are highly sensitive to the viscosity. In contrast, the Disp/Comb selectivity inside the cage [Disp(cage) /Comb(cage) ] is rather insensitive. The difference in viscosity dependence between Disp(cage) /Comb(cage) and Disp(dif) /Comb(dif) is explained by the spin state of the radical pair inside and outside the cage and the spin state dependent configurational changes of the radical pair upon their collision. Given that the configurational change of the radicals associates the displacement and reorganization of solvents around the radicals, the termination outside the cage, which requires larger change than that inside the cage, is highly viscosity dependent. Furthermore, while the bulk viscosity of each solvent shows good correlation with Fdif and Disp/Comb selectivity, microviscosity is the better parameter predicting Fdif and Disp(dif) /Comb(dif) selectivity regardless of the solvents.

Shape selectivity in toluene disproportionation into para-xylene generated by chemical vapor deposition of tetramethoxysilane on MFI zeolite catalyst

Dependence of shape selectivity for para-xylene production by toluene disproportionation on conditions of chemical vapor deposition (CVD) of tetramethoxysilane on MFI (ZSM-5) zeolite were investigated in detail. The CVD after pelletization was necessary to obtain 0.7–1 mm particles with high selectivity. The influences of preparation conditions on the selectivity were investigated in detail to find the optimum conditions. The parent zeolite with small number of Brønsted acid sites on the external surface brought the high selectivity after the CVD. The catalyst prepared in the optimized conditions showed the selectivity 99.7% at ca. 10% of the toluene conversion.

Spectroscopic Investigations of Catalase Compound II: Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme.

We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pKa = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pKa in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules.

Termination Mechanism of the Radical Polymerization of Acrylates.

The termination mechanism of the radical polymerization of acrylates, namely the selectivity of disproportionation (Disp) and combination (Comb) between polymer end radicals, is unambiguously determined by the reaction of polyacrylate end radicals generated from corresponding "living" organotellurium ω-end polymer. While textbooks describe the occurrence of Comb, the reaction at 25 °C exclusively gives the Disp products. Ab initio molecular dynamics suggests that the products form by two pathways: The direct disproportionation reaction and a novel stepwise process that involves the initial formation of the C-O coupling product followed by intramolecular rearrangement. The termination at high temperature and low radical concentration increases the contribution of back-biting reaction giving mid-chain radicals, and complex reaction pathways of the mid-chain radicals are clarified for the first time.

Kinetic Studies of Xylene Transformation Reactions Over ZSM-5 Zeolite

A systematic study on the influence of reaction time and temperature during transformation reaction of m-, o- and p-xylene has been carried out over HZSM-5 catalyst using a riser simulator reactor system. The product selectivities have revealed that isomerization and disproportionation are the primary reactions. A higher conversion was observed for p-X as compared to that of m-X and o-X at all temperatures and all concentrations of ZSM-5. The highest selectivity of isomerization (100 %) was observed for p-X and o-X at 200 °C over 20 % ZSM-5, whereas the highest disproportionation selectivity (25 %) was observed for m-X at 400 °C over 10 % ZSM-5. The order of reactivity was observed to be dependent upon the concentration of ZSM-5. When ZSM-5 concentration was 10 % the order of reactivity was p-X > m-X > o-X, whereas at a higher concentration of ZSM-5 the order of reactivity was p-X > o-X > m-X. The experimental results have been modeled also using quasi-steady-state approximation. Kinetic parameters for o-X, m-X and p−X conversions into isomerization and disproportionation products were calculated using the catalyst activity decay function based on the time on stream. The apparent activation energies for disproportion as well as for the combined isomerization reactions over 10 % ZSM-5 catalyst were found to decrease as follows: E p-X > E m-X > E o-X . It was also noted that when concentration of ZSM-5 was increased from 10 to 20 % the activation energies were increased for isomerization reactions but decreased for disproportionation reactions.

Occupational Exposures to Noise Resulting from the Workplace Use of Personal Media Players at a Manufacturing Facility

This study examined the contribution of noise exposures from personal media player (PMP) use in the workplace to overall employee noise exposures at a Colorado manufacturing facility. A total of 24 workers’ PMP and background noise exposures were measured. Twelve PMP users worked in high-background-noise exposure (HBNE) areas, and 12 worked in low-background-noise exposure (LBNE) areas. The self-selected PMP listening level of each worker was measured using an ear simulator, and the background noise of each employee workstation was measured using a sound level meter. Workers’ self-reported PMP duration of use, PMP listening exposure levels, and background noise levels were used to estimate the daily occupational noise exposures. Measured background noise levels averaged 81 dBA for HBNE workers and 59 dBA for LBNE workers. Measured, free-field equivalent listening exposure levels were significantly greater for HBNE workers (85 dBA) compared with LBNE workers (75 dBA) (p = 0.0006). Estimated mean daily noise exposures for both groups were below the ACGIH threshold limit value for noise of 85 dBA8-hr time weighted average (TWA), specifically 84 dBA TWA for HBNE workers and 72 dBA TWA for LBNE workers. Three of 12 (25%) HBNE workers had estimated exposures greater than 85 dBA TWA when only background noise was considered, yet when PMP use was also considered, 6 of 12 (50%) had estimated exposures greater than 85 dBA TWA, suggesting that PMP use doubled the number of overexposed workers. None of the LBNE workers had estimated exposures greater than 85 dBA TWA. The contribution of PMP use to overall noise exposures was substantially less among HBNE workers than LBNE workers due to the disproportionate selection of noise-attenuating headsets among HBNE workers compared with LBNE workers. It is recommended that the facility management either restrict workplace PMP use among HBNE workers or require output-limiting technology to prevent occupational noise-induced hearing loss.

ChemInform Abstract: Transformation of m-Xylene Over Al-Pillared Clays and Ultrastable Zeolite Y.

The reaction of m-xylene has been carried out at 623 K over Al-pillared beidellite and montmorillonite, and over ultrastable zeolite Y (USY) as a reference catalyst. These microporous acidic solids exhibit similar open porosities and, therefore, the activity toward disporportionation and/or isomerization is not primarily ruled by geometrical limitations but merely reflects the relative amount and strength of the acid sites, strong Broensted acid sites being required for disproportionation and weaker ones for isomerization. In terms of overall conversion and disproportionation selectivity, USY is more active than the pillared clays. This is due to a higher content of strong acid sites and to the greater micropore volume of USY. Al-pillared beidellite is more active than Al-pillared montmorillonite, which is interpreted in terms of framework substitution differences between the two clays. The OH/Al molar ratio of the starting pillaring solution does not confer to the pillared materials any significant effect on their catalytic performances. Deactivation is observed for all the catalysts, and there is some evidence that the stronger sites would deactivate first. 40 refs., 3 tabs., 2 tabs.

Effect of pore size and acidity on the coke formation during ethylbenzene conversion on zeolite catalysts

The present work provides solid-state 13C NMR spectroscopic evidence that the zeolites acidity and the pore size strongly affect the catalytic behavior of ethylbenzene disproportionation and coke formation. The medium-pore zeolite H-ZSM-5 ( ca. 0.56 nm) and the large-pore zeolite H-Y ( ca. 0.74 nm) used in this study have exclusively Brønsted acid sites, but with different acid strength. Due to the transition state shape selectivity of ethylbenzene disproportionation, ethylbenzene transalkylation on H-Y takes place at low reaction temperature without side-reactions. On H-ZSM-5, dealkylation/realkylation was observed and generation of alkylcarbenium ions resulted in secondary reactions. These alkylcarbenium ions initiate coke formation on zeolite H-ZSM-5 via oligomerization, six-ring closure, and aromatization of alicyclic hydrocarbons. Ethylbenzene disproportionation on large-pore zeolites Y is an attractive reaction due to its low reaction temperature, high selectivity without side-reactions, and low coke formation. Medium-pore zeolite H-ZSM-5 showed higher reactivity for dealkylation of ethylbenzene and protolytic cracking of light alkanes due to its narrow channels and stronger Brønsted acid sites.

Spatial attention and response control in healthy younger and older adults and individuals with Alzheimer's disease: Evidence for disproportionate selection impairments in the simon task.

The authors examined the degree to which aging and Alzheimer's disease (AD) influence the ability to control attention when conflict is presented in terms of incongruent mapping between a stimulus and the appropriate response. In a variant of the Simon task, healthy older adults and older adults with mild or very mild AD showed disproportionately larger reaction time (RT) costs when the stimulus and response were in conflict relative to RT costs of healthy younger adults. Analyses of RT distributions provide support for a 2-process model of the Simon effect in which there is a short-lived transient effect of the irrelevant dimension in younger adults and a more sustained influence across the RT distribution in older adults. An analysis of error rates showed that the older adults with mild and very mild AD made more errors on incongruent trials, suggesting that AD leads to increased likelihood of selecting the prepotent pathway. The findings are discussed in terms of the special nature of the response requirements of the Simon task to better illuminate the attentional decrements in both healthy aging and early stage AD.

Winter habitat selection by female moose in western interior montane forests

Winter range has been identified as an important component of moose ( Alces alces (L., 1758)) conservation in managed forests, yet there have been few studies on habitat associations in montane ecosystems. We investigated habitat selection by moose at landscape and stand scales during late winter in southeastern British Columbia using global positioning system (GPS) collars on 24 adult moose cows in each of two winters. The strongest determinant of late-winter range at the landscape scale was decreasing elevation, while moose also selected for areas of gentler slopes and higher solar insolation. Elevation likely is a surrogate for snow depth, which is probably the primary causative factor influencing late-winter distribution of moose. Within late-winter range, topographic variables had little influence on moose habitat selection. Lower crown closure was the strongest determinant of stand-scale selection, although the resultant model was weak. We found no disproportionate selection for stands with high crown closure, and there was little evidence for greater use of cover stands with increasing snow as winter progressed. Within late-winter range, moose selected forage habitats (42% use vs. 30% availability) over cover habitats (22% use vs. 37% availability). The delineation of late-winter moose range can be based on snow depth, or elevation as its surrogate.

Increase in Selectivity of Toluene Disproportionation and in p-Xylene Yield by Optimization of Zeolite Microporous Structure

The possibility of increasing the yield of target products and para-selectivity of toluene disproportionation on modified zeolites by optimization of their microporous structure was studied.

Ni–Pt/H–Y Zeolite Catalysts for Disproportionation of Toluene and 1,2,4-trimethylbenzene

Ni–Pt/H–Y zeolite catalysts with different Ni contents were prepared and applied to the disproportionation of toluene and 1,2,4-trimethylbenzene in the temperature range 250–400 °C. The line broadening XRD analysis indicates that the increasing Ni addition decreases the crystallinity of zeolites. ESCA studies show the complete reduction of Ni species up to 0.3 wt.% Ni addition over 0.1 wt.% Pt/H-Y and further addition leads to the occurrence of unreduced nickel species as NiAl2O4. A TEM study shows the formation of bimetallic (Ni–Pt) particles of nanoscale size and the average particle size is found to increase with increasing Ni loading. Acidity measurements by NH3-TPD and pyridine-adsorbed FT–IR spectroscopy show the increasing occupation of acid sites by increasing nickel loading. The catalytic activity of Ni–Pt/H–Y zeolite and Pt/H–Y catalysts was compared and it was found that addition of Ni up to 0.3 wt.% increases conversion of toluene and 1,2,4-trimethylbenzene, disproportionation selectivity and sustainability of the catalysts. Further addition of Ni leads to a decrease in conversion and disproportionation selectivity and increasing dealkylated products, which may be due to the presence of unreduced Ni species and pore blockage by large-sized bimetallic particles formed.

US Valuation of the EQ-5D Health States

The EQ-5D is a brief, multiattribute, preference-based health status measure. This article describes the development of a statistical model for generating US population-based EQ-5D preference weights. A multistage probability sample was selected from the US adult civilian noninstitutional population. Respondents valued 13 of 243 EQ-5D health states using the time trade-off (TTO) method. Data for 12 states were used in econometric modeling. The TTO valuations were linearly transformed to lie on the interval [-1, 1]. Methods were investigated to account for interaction effects caused by having problems in multiple EQ-5D dimensions. Several alternative model specifications (eg, pooled least squares, random effects) also were considered. A modified split-sample approach was used to evaluate the predictive accuracy of the models. All statistical analyses took into account the clustering and disproportionate selection probabilities inherent in our sampling design. Our D1 model for the EQ-5D included ordinal terms to capture the effect of departures from perfect health as well as interaction effects. A random effects specification of the D1 model yielded a good fit for the observed TTO data, with an overall R of 0.38, a mean absolute error of 0.025, and 7 prediction errors exceeding 0.05 in absolute magnitude. The D1 model best predicts the values for observed health states. The resulting preference weight estimates represent a significant enhancement of the EQ-5D's utility for health status assessment and economic analysis in the US.

Conversion of xylene over mordenites: an operando infrared spectroscopy study of the effect of Na +

A series of progressively proton-exchanged sodium mordenite samples was studied by operando infrared spectroscopy during xylene conversion. This unique, powerful tool allowed us to characterize the species adsorbed to the surface during catalysis and to follow the evolution of the active sites as the reaction proceeded. We were then able to correlate the surface data with the catalytic results obtained by gas-phase chromatography analysis. When very few hydroxyls are present on site O 7H close to the main-channel walls, the initial isomerization selectivity is very high and the high Na + content leads to the preferential adsorption of 1,2,4-TMB inside the micropores. When the amount of acidic hydroxyls increases, new sites O 2H are generated at the intersection between main channels and side pockets. The initial disproportionation selectivity then increases roughly. Finally, the last hydroxyls appear on site O 9H located at the end of the side pockets. These constrained hydroxyls are not accessible to the reactant in the reaction conditions, but their presence leads to a global activity increase without any selectivity modification. Acid strength considerations, together with the observation of the “working hydroxyls,” indicate an indirect effect of O 9H on the overall activity, which is probably related to a modification in the void space inside the micropores.

Effects of zeolite pore sizes on the mechanism and selectivity of xylene disproportionation—a DFT study

The disproportionation reaction of xylenes, catalyzed by acidic zeolites, is investigated by means of periodic ab initio calculations. Two relevant 10- and 12-membered ring (MR) frameworks are chosen: theta-1 (TON) and mordenite (MOR). As a first step, two bimolecular mechanisms proposed for this reaction are investigated: the first one is assumed to occur through a one-step methyl shift and involves a highly unstable methyl cation as a transition state. The second and energetically favored mechanism implies the formation of a benzylic-like carbocation, subsequently converted into a trimethyldiphenylmethane, also called DPM intermediate. The energetics of this reaction path are mainly governed by the different sterical constraints induced by the 10-MR or 12-MR zeolites on the DPM intermediates. Therefore, the relative stability of the DPM inside the pores appears as the key parameter for understanding the selectivity observed experimentally.