Effect Of Sample Composition Research Articles

Talents from abroad. Foreign managers and productivity in the United Kingdom

In this paper, we test the contribution of foreign management to firm productivity. We use a novel data set on the careers of 115,505 managers employed in 10,238 firms in the UK from 2009–2017. We find that domestic manufacturing firms become, on average, 4.9% more productive and about 23.3% more capital intensive after hiring foreign managers. In particular, we find that prior industry-specific experience of foreign managers abroad allows spillover effects to domestic recruiting firms. On the other hand, we find no significant effect on foreign-owned firms after hiring foreign managers, possibly because technological spillovers have already occurred after takeovers by headquarters. The marginal productivity gain is twice as high when the new hires end up on all-British boards without a history of diversity. Our identification strategy combines matching techniques, difference-in-difference and pre-recruitment trends to challenge reverse causality. The results are robust to different specifications and sample composition effects. Ultimately, our results show how restrictions on the global mobility of managerial talent hamper the competitiveness of the domestic industry.

The Predictive Validity of the GRE Across Graduate Outcomes: A Meta-Analysis of Trends Over Time

ABSTRACT This meta-analysis assesses the predictive validity of the Graduate Record Examination (GRE) across outcome variables, including grade point average, for graduate students. In addition to aggregate effects, this paper also assessed changes in observed effects over time as related to increasing diversity in the graduate student population and as a function of gender and racial/ethnic composition of study samples. Framed using a lens of critical whiteness, this analysis examined n = 1,659 individual effects across k = 201 studies. Overall, 62.3% of reported effects were nonsignificant (i.e. no predictive value of GRE scores on student outcomes). Further, the magnitude of observed predictive relationships decreased significantly over time. The aggregate mean effect across all studies and outcomes was small, significant, and positive: GRE score predicted 3.24% of variance across measured outcomes, 4% of variance in overall GPA, and 2.56% of variance in first-year graduate GPA. Sample composition effects by race/ethnicity were notable under some conditions, but nonsignificant, with increasing proportions of people of Color within a study sample associated with poorer predictive validity for GPA. Likewise, the magnitude of negative effects where lower GRE scores predicted stronger student outcomes showed increasing trends from 0.16% of variance for all-white samples to 7.3% for samples comprised entirely of people of Color.

NiO@MXene Nanocomposite as an Anode with Enhanced Energy Density for Asymmetric Supercapacitors

MXene composites with different metal oxides have recently demonstrated good electrochemical performance with enhanced conductivity and also hinder the restacking of MXene. With this motivation, we synthesized the nickel oxide@MXene (NO@MXene) series with varying compositions, which was screen-printed on a flexible stainless-steel mesh (FSSM) substrate as an anode for a supercapacitor. The effect of sample composition, i.e., 5% NO@MX, 10% NO@MX, 15% NO@MX, and 20% NO@MX, on the electrochemical properties is studied systematically. The 15% NO@MX composite electrode demonstrated a maximum capacitance of 1542 F g–1@6 mA cm–2 current density in 1 M KOH. An all-solid-state asymmetric supercapacitor (ASC) with 15% NO@MX (anode) and copper oxide (cathode) displayed a 1 V potential window. The device exhibited a specific capacitance of 73.3 F g–1@10 mA cm–2 current density with a maximum energy density of 10.7 Wh kg–1 and a power density of 3333 W kg–1 in polymer gel of PVA–KOH electrolyte. The cyclic stability of the device demonstrates 90.6% capacitance retention over 5000 cycles. It is envisaged that 15% NO@MX as an anode would serve as a promising electrode for the all-solid-state device for supercapacitor applications.

Steam/CO2 Reforming of Methane Over Impregnated Ni/CeO2 Catalysts: Effect of Sample Composition on Their Activity and Stability

Steam/CO2 reforming of methane was studied at 600–900 °C, molar ratio CO2/H2O 0–2 and contact time 0.04–0.15 s over impregnated Ni/CeO2 catalysts of various compositions. It has been established that with an increase in the Ni content from 2 to 10 wt.%, both the conversion of reactants (X) and the yield of products (Y) increase in the range XCH4 25→80%, XCO2 35→72%, YH2 30→80%, YCO 30→75% (at 750 °C). With a further increase in the nickel content to 15%, the process parameters changed slightly, reaching a plateau. Higher nickel content (10 vs. 2 wt.%) ensures stable operation of the catalyst over time. The functional performance of the catalysts was correlated with physicochemical properties of as-synthesized, activated and spent samples using X-ray fluorescence analysis, low-temperature nitrogen adsorption, X-ray diffraction analysis, electron microscopy, and thermal analysis. It was shown that the Ni content affects the thermal stability, the textural, structural and redox characteristics of the samples. The 10% Ni/CeO2 catalyst was chosen as the optimal one due to higher H2 productivity, and sufficient resistance to sintering and coking. This sample provides a stable hydrogen yield of 85% in steam/CO2 reforming of methane at 800 °C, CO2/H2O = 2 and a contact time 0.15 s.

The Effect of Sample Composition on Inference for Random Effects Using Normal and Dirichlet Process Models

Good inference for the random effects in a linear mixed-effects model is important because of their role in decision making. For example, estimates of the random effects may be used to make decisions about the quality of medical providers such as hospitals, surgeons, etc. Standard methods assume that the random effects are normally distributed, but this may be problematic because inferences are sensitive to this assumption and to the composition of the study sample. We investigate whether using a Dirichlet process prior instead of a normal prior for the random effects is effective in reducing the dependence of inferences on the study sample. Specifically, we compare the two models, normal and Dirichlet process, emphasizing inferences for extrema. Our main finding is that using the Dirichlet process prior provides inferences that are substantially more robust to the composition of the study sample.

Micellar electrokinetic chromatography of organic and peroxide-based explosives

CE methods have been developed for the analysis of organic and peroxide-based explosives. These methods have been developed for deployment on portable, in-field instrumentation for rapid screening. Both classes of compounds are neutral and were separated using micellar electrokinetic chromatography (MEKC). The effects of sample composition, separation temperature, and background electrolyte composition were investigated. The optimised separation conditions (25mM sodium tetraborate, 75mM sodium dodecyl sulfate at 25°C, detection at 200nm) were applied to the separation of 25 organic explosives in 17min, with very high efficiency (typically greater than 300,000 platesm−1) and high sensitivity (LOD typically less than 0.5mgL−1; around 1–1.5μM). A MEKC method was also developed for peroxide-based explosives (10mM sodium tetraborate, 100mM sodium dodecyl sulfate at 25°C, detection at 200nm). UV detection provided LODs between 5.5 and 45.0mgL−1 (or 31.2–304μM), which is comparable to results achieved using liquid chromatography. Importantly, no sample pre-treatment or post-column reaction was necessary and the peroxide-based explosives were not decomposed to hydrogen peroxide. Both MEKC methods have been applied to pre-blast analysis and for the detection of post-blast residues recovered from controlled, small scale detonations of organic and peroxide-based explosive devices.

Measurement of the sulphur isotope ratio (34S/32S) in uranium ore concentrates (yellow cakes) for origin assessment

A novel method has been developed for the measurement of the 34S/32S isotope ratio in uranium ore concentrate (yellow cake) samples for origin assessment in nuclear forensics. The leachable sulphate is separated and pre-concentrated by anion exchange separation followed by the 34S/32S ratio measurement by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The effect of sample composition on the accuracy was investigated and optimized. Matching of the sample to the bracketing standard was necessary to obtain accurate results. The method was validated by the measurement of standard reference materials (IAEA-S-2, IAEA-S-3 and IAEA-S-4) and the δ34S value could be determined with an uncertainty between 0.45‰ and 1.9‰ expressed with a coverage factor of 2. The method was then applied for the analysis of uranium ore concentrates of world-wide origin. In the studied materials distinct 34S/32S isotope ratios could be observed, which can be a promising signature for the nuclear forensic investigations to identify the source of unknown nuclear materials.

Dissolution Kinetics of Magnesite Waste in HCl Solution

In this study, the dissolution of electro-filter magnesite dust samples that were collected from different places in an electrostatic bag house in HCl solution was investigated. The effects of sample composition and variations in the leaching parameters, such as reaction temperature, time, and acid concentration, were studied to elucidate the kinetics of the dust dissolution. The results obtained in this study clearly indicate that the dissolution of the magnesite dust increased with increasing acid concentration and leaching temperature. However, the tests on the effect of temperature, carried out at a constant reagent concentration of 0.5 M HCl, showed that the contribution of the increase in temperature on the dissolution rate was more powerful than that of the reagent concentration. At a temperature range between 290 and 318 K, the rate constants k were calculated as a function of temperature, and the following values were obtained: k = 2.71 × 108 exp(−7550/T) min–1 for EFDS-1, k = 1.31 × 107 exp(−652...

Are Internet surveys an alternative to face-to-face interviews in contingent valuation?

Internet is an increasingly popular data collection mode for stated preference research in environmental economics. However, little is known about how this survey mode may influence data quality and welfare estimates. As part of a national contingent valuation (CV) survey estimating willingness to pay (WTP) for biodiversity protection plans, we assign two groups of respondents either to an Internet or face-to-face (in-home) interview mode. Our design aims to better isolate measurement effects from sample composition effects by drawing both samples from the same sample frame. We find little evidence of social desirability bias in the interview setting or satisficing (shortcutting the response process) in the Internet survey. The share of “don't knows”, zeros and protest responses to the WTP question with a payment card is very similar between modes and equality of mean WTP cannot be rejected. Results are fairly encouraging for the use of Internet in CV as stated preferences do not seem to be significantly different or biased compared to face-to-face interviews.

Study of kinetics of co-pyrolysis of coal and waste LDPE blends under argon atmosphere

Co-pyrolysis of coal with waste plastic is increasingly being looked upon as a potential technique to counter the present day challenges in energy and waste management by harnessing the multiple benefits associated with the same. In the present work, the kinetics of co-pyrolysis of waste LDPE carried out with coal of Ledo origin from the coalfields of Assam (India) has been studied. A thermo-gravimetric (TG) study of the co-pyrolysis has been carried out taking waste LDPE-coal mixtures in ratios of 3:1, 1:1, and 1:3 by weight and at five varying heating rates from 5 to 25 K min −1 with a 5 K increment. Experiments were also carried out for the individual components at all the five heating rates. This TG analysis data was used to evaluate the kinetics parameters such as the activation energy, pre-exponential factors, and the reaction orders, applying a model fitting approach. The results of the kinetics analysis indicate higher activation energy for the mixtures. With increase in the coal percentage, the reaction order is found to increase. Also the synergistic effect between the two sample species in the mixtures has been studied and found to indicate presence of interaction between coal and LDPE. The effect of sample composition on the products of co-pyrolysis has also been compared.

Can Cheap Panel-Based Internet Surveys Substitute Costly In-Person Interviews in CV Surveys?

Internet is an increasingly popular data collection mode for stated preference research in environmental economics. However, little is known about how this survey mode may influence data quality and welfare estimates. As part of a national contingent valuation (CV) survey estimating willingness to pay (WTP) for biodiversity protection plans, we assign two groups of respondents either to an Internet or face-to-face (in-home) interview mode. Our design aims to better isolate measurement effects from sample composition effects by drawing both samples from the same sample frame. We find little evidence of social desirability bias in the interview setting or satisficing (shortcutting the response process) in the Internet survey. The share of “don’t knows”, zeros and protest responses to the WTP question with a payment card is very similar between modes and equality of mean WTP cannot be rejected. Results are fairlyencouraging for the use of Internet in CV as stated preferences do not seem to besignificantly different or biased compared to face-to-face interviews.

Technological diffusion, the diffusion of skill and the growth of outsourcing in US manufacturing

What drives the observed rapid growth of outsourcing in US manufacturing? This article approaches this question by asking whether technological diffusion driven by R&D spillovers is in part responsible for the growth of atypical work arrangements in the USA. Relying on data of technological diffusion since the early 1970s, this study provides some evidence that technological factors may have contributed to the spread of outsourcing. When sample composition effects are accounted for, technological innovation reduces outsourcing in high-tech industries. Furthermore, this study highlights the importance of distinguishing between ‘rent’ and ‘pure knowledge’ spillovers. Rent spillovers are positively correlated with outsourcing, whereas pure knowledge spillovers usually decrease the incentive to outsource. Support to the technological diffusion hypothesis is also found, particularly in a sample of high-tech industries after 1980, in which rapid diffusion of IT technologies is notoriously witnessed. Alternative hypotheses are better applied to low-tech industries.

Study on fluorescence of Maillard reaction compounds in breakfast cereals

During the advanced stage of the Maillard reaction (MR) in food processing and cooking, Amadori rearrangement products undergo dehydration and fission and fluorescent substances are formed. Free and total (free + linked to the protein backbone) fluorescence (FIC) due to Maillard compounds in 60 commercial breakfast cereals was evaluated. Pronase was used for efficient release of linked fluorescent Maillard compounds from the protein backbone. Results were correlated with some heat-induced markers of the extent of the MR or sugar caramelisation during cereal processing, such as hydroxymethylfurfural, furfural, glucosilisomaltol and furosine. The effect of sample composition (dietary-fibre added, protein, etc.) on levels of FIC, expressed as fluorescence intensity (FI) per milligram of sample, is discussed. FIC is significantly correlated to the protein content of the sample and fluorescent Maillard compounds are mainly linked to the protein backbone. The ratio of total-FIC to free-FIC was 10.4-fold for corn-based, wheat-based and multicereal-based breakfast cereals but significantly higher in rice-based samples. Addition of dietary fibre or honey increased the FIC values. Data support the usefulness of FIC measurement as an unspecific heat-induced marker in breakfast cereals.

Gel, thermal, and X-ray diffraction characterization of virgin, scrapped polyethylene and its blends

The characterizations of virgin and scrapped polyethylene samples (VPE and SPE) and VPE/SPE blends were studied using different analytical techniques. The obtained data regarding crosslink density demonstrated that the radiation-induced crosslinking of VPE, SPE, and VPE/SPE samples increased as a result of increasing irradiation dose, blending VPE with SPE, and loading the VPE/SPE blend with trimethylol propane triacrylate (TMPTA). The use of differential scanning calorimetry technique was aimed at revealing the effect of sample composition (VPE, SPE, and VPE/SPE) and also the effect and type of irradiation on the melting temperature (Tm) and the heat of transformation (ΔHf). The melting temperature and heat of transformation increased with increasing either irradiation dose or loading the polymeric samples with TMPTA. In addition, the application of thermogravimetric analysis (TGA) was used to study the degradation characteristics of the polymeric samples in terms of onset temperature (Ti), temperature at maximum weight loss (Ts), and activation energy (Ea). The TGA results showed that the irradiation (EB and γ-rays) and loading of polymeric samples with TMPTA led to a thermally stable polymeric matrix with higher Ti, Ts, and Ea values. The blank SPE sample or those blend rich in SPE matrix were highly thermally stable than that blank VPE one. The X-ray diffraction investigation illustrated that VPE samples undergoes phase transformation between orthorhombic, monomclinic, and/or hexagonal as a result of irradiation. POLYM. COMPOS. 27:709–717, 2006. © 2006 Society of Plastics Engineers

Effect of sample composition on electrophoretic migration: Application to hemoglobin analysis by capillary electrophoresis and agarose electrophoresis

The electrophoretic migration, in routine analysis, is crucial for compound identification especially when multiple components are present in the sample. In complex or crude samples, such as those obtained from biological fluids, electrophoretic migration often does not correspond well to that of a pure standard compound. Several factors, related to the sample itself, have been identified as modulating the electrophoretic migration in zone electrophoresis both in gel and capillary electrophoresis (CE): solute mobility and concentrations, salt content, and protein interaction in the sample. Peak shape asymmetry often signals changes in migration especially when comparing samples with wide differences in concentration or those containing high ionic strength. Also, the migration of a protein can be influenced by the presence of a high concentration of another slowly migrating protein in the sample. A weak interaction during the separation between the two proteins which lead to a decreased velocity has been postulated. This was confirmed by finding a curve–linear relationship between the ratio of the two hemoglobin (Hb) variants, hemoglobin F (Hb F) and hemoglobin S (Hb S), and the distance between the two in gel electrophoresis (GE); and also by the observation of formation of a new small peak based on the analysis of hemoglobin F by capillary electrophoresis upon the addition of Hb S to the separation buffer. These factors when present together have an additive effect on the migration. As an example, Hb F, present in low but variable concentration in patients with sickle cell disease (Hb S), migrates in gel electrophoresis slightly slower than it is expected; enough to be confused with other unknown variants. However, the small peaks with different migration distances between Hb S and the adult Hb (Hb A) correlated well ( r=0.98) with Hb F performed by an alkali-denaturing assay indicating that these peaks are indeed Hb F in spite of the difference in their migration.

Synthesis of methylamines from CO 2, H 2 and NH 3 over Cu–Mg–Al mixed oxides

The synthesis of methylamines from carbon dioxide, hydrogen, and ammonia has been studied over catalysts derived from Cu–Mg–Al lamellar double hydroxides (LDH) with hydrotalcite-like structure. Catalysts containing 33 at.% Cu(II) related to the total metal content, with different ratios of Mg(II) to Al(III), and a binary Cu–Al catalyst containing 67 at.% Cu were prepared by precipitation of metal nitrates with sodium carbonate. The effect of sample composition and of calcination temperature on the catalytic behaviour has been investigated. Catalytic tests were performed in a fixed-bed microreactor in the temperature range 473–573 K and at 0.6 MPa total pressure. Activity for methylamine formation increased for the ternary catalysts with increasing ratio x=M(III)/[M(II)+M(III)]. Maximum activity was observed for a catalyst with x=0.33, for which XRD analysis indicated a pure hydrotalcite-like phase. Increasing the calcination temperature of this sample from 673 K to 773 K improved the activity, whereas a significant loss in activity was observed when calcined at 873 K. This behaviour could be traced to the copper surface area, which increased from 4 to 14 m 2 g −1 (773 K) and then decreased to 9 m 2 g −1 (873 K), depending on calcination temperature. After catalytic testing the catalysts calcined up to 773 K consisted of dispersed copper in an amorphous oxide matrix, whereas calcination at 873 K caused the additional formation of CuAl 2O 4. Distribution of the methylamines was similar for all catalysts with the fraction of monomethylamine being higher than 80%, besides of smaller amounts of di- and trimethylamine. Other carbon containing products observed were carbon monoxide, formed by the reverse water–gas shift reaction (RWGSR), and methanol in the absence of ammonia in the feed. No general correlation between either BET or copper surface area and catalytic activity was observed. However, for the Cu–Mg–Al catalyst with x=0.33 calcined at different temperatures activity for methylamine formation roughly parallelled the copper surface area measured by N 2O-titration.

Morphological studies of lightly-sulfonated polystyrene using 23Na NMR. 1. Effects of sample composition

[sup 23]Na nuclear magnetic resonance (NMR) is used to observe the sodium cations in sulfonated polystyrene ionomers (NaSPS). Three NMR peaks are detected, corresponding to isolated ion pairs, aggregated ions, and hydrated ions. Peak intensities vary with sample composition and treatment and provide insight into the effects of these variables on the morphology of the ionomer. Ion distributions are systematically influenced by hydration treatment, sulfation level, and neutralization level. Fully dried NaSPS at low ion content shows isolated and aggregated sodium ions. Once humidified, the single peak at 0 ppm characteristic of fully hydrated sodium ions indicates that all sodium ions in the NaSPS are available for hydration. As the sulfonation level increases, the fraction of sodium ions held in isolated ion pairs decreases while the fraction of ionic species in aggregates increases. This coincides with a shift in the peak position of the aggregated sodium ions to lower frequency, indicative of increased quadrupolar interactions. Finally, as the neutralization level increases at a constant 3.4% sulfonate content, the aggregate peak shifts to higher frequency due to incorporation of the neutralizing agent, NaOH, into the aggregates. At very high neutralization levels, a separate NMR peak characteristic of phase-separated NaOH appears.

Hyperfine magnetic fields of disordered systems by /sup 57/Fe Mossbauer spectroscopy

The feasibility of /sup 57/Fe transmission Mossbauer spectroscopy in the study of hyperfine magnetic fields is described with emphasis on amorphous, nanocrystalline and quasicrystalline alloys. Distributions of hyperfine magnetic fields obtained are presented via three-dimensional projections where effects of sample composition, temperature and annealing time on magnetic structure are followed by changes in probability of the field values. This allows magnetic transitions as well as mixed electric-quadrupole and magnetic-dipole interactions to be observed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The effect of sample composition and vial type on Ĉerenkov counting in a liquid scintillation counter

The effect of sample vial type and sample composition on the Ĉerenkov count rate detected from 32P and 36Cl was studied using a liquid scintillation counter. When counting was done in the noncoincident mode, glass vials allowed higher counting efficiency than plastic vials. In the coincident mode light scattering caused by polyethylene and polyproplyene vials allowed higher counting efficiency than glass vials. Highest coincident counting efficiency was from plastic minivials in a glass carrier vial. Increased solute concentration in samples caused increased counting efficiency due to changes in the refractive index of the solution. This can cause significant counting efficiency changes with no sample channel ratio change in density gradient fractions. The use of wavelength shifters is shown to be inappropriate when the sample pH varies, as this can change the fluorescent properties of the shifters and thereby the observed count rate.

Effects of Sample Composition on Coefficient Estimation and Hypothesis Testing by Correlation with a Dummy Variable

This paper explored sample composition as a potential source of error in coefficient estimation and hypothesis testing by correlation with a dummy variable. Specific examples were provided to demonstrate to researchers the significance of this source of error. Although the problem is examined in light of the statistical consequences, composition of the sample, which is the actual source of error, is a methodological issue.