Absence Of Interaction Effects Research Articles

Higher-order topological superconductors from Weyl semimetals

We propose that doped Weyl semimetals with {time-reversal and certain crystalline symmetries} are natural candidates to realize higher-order topological superconductors, which exhibit a fully gapped bulk while the surface hosts robust gapless chiral hinge states. We show that in such a doped Weyl semimetal, a featureless finite-range attractive interaction favors a p+ip pairing symmetry. By analyzing its topological properties, we identify such a chiral pairing state as a higher-order topological superconductor, which depending on the existence of a four-fold rotoinversion symmetry, is either intrinsic, {meaning that the corresponding hinge states can only be removed by closing the bulk gap, rather than modifying the surface states}, or extrinsic. We achieve this understanding via various methods recently developed for higher-order topology, including Wannier representability, Wannier spectrum, and defect classification approaches. For the four-fold rotoinversion symmetric case, we provide a complete classification of the higher-order topological superconductors. We show that such second-order topological superconductors exhibit chiral hinge modes that are robust in the absence of interaction effects but can be eliminated at the cost of introducing surface topological order.

Unraveling the role of retrieval deficits in autobiographical memory impairment in schizophrenia: A comparison of involuntary and voluntary autobiographical memories

Patients with schizophrenia show severe autobiographical memory impairment, thought to reflect retrieval deficits caused by executive dysfunction. However, prior research has focused exclusively on strategic (voluntary) retrieval, and ignored involuntary retrieval resulting from automatic and associative processes, involving minimal cognitive control. We report two studies with patients diagnosed with schizophrenia (Ns = 40 and 50 respectively) comparing their impairment in involuntary versus voluntary autobiographical memory. We use two different methodologies, not previously used in schizophrenia research: a naturalistic study involving real-life data and an experimental setup. Both studies consistently showed that involuntary and voluntary autobiographical memories were similarly impaired in schizophrenia. The absence of interaction effects between group and retrieval suggests that schizophrenic patients did not benefit from memory tasks involving little retrieval effort. These findings suggest that autobiographical memory impairment in schizophrenia are not caused by problems with self-initiated voluntary retrieval, but instead likely reflect encoding or binding deficits.

PROBLEM-BASED LEARNING STRATEGIES USING MULTIPLE REPRESENTATIONS AND LEARNING STYLES TO ENHANCE CONCEPTUAL UNDERSTANDINGS OF CHEMISTRY

Studies in the area of chemistry teaching discovered that problem-based learning strategies (PBL) effectively improve students’ conceptual understanding. However, there is minimal information about the effectiveness of PBL if it is applied with multiple representations (MR) for the students with different learning preferences. This study aimed to prove the effects of problem-based learning strategies (PBL) using multiple representations (MR) and students’ learning styles on the conceptual understanding in chemistry. There were two whole classes in the Mechanical Engineering Department of Bali State Polytechnic that were assigned to be the experimental group (n =59) and control group (n = 58). Felder-Soloman's Index of Learning Style (ILS) was applied to differentiate the students’ learning preferences, while their conceptual understanding in chemistry was assessed using a test after 6 weeks of treatment. The analysis of covariance (ANCOVA) shows that the conceptual understanding of students taught using PBL strategies with MR was significantly better than those taught using PBL strategies only. Besides, based on the variation of learning styles, students with a visual style had a better conceptual understanding than those with verbal style, but the difference was not statistically significant. The absence of interaction effect between PBL strategies with MR and learning style on students’ conceptual understanding suggests that the support of multiple representations in PBL strategies can effectively enhance students' understanding of concepts in chemistry regardless of their learning style.

BEHAVIORAL BACKGROUND OF CARDIOVASCULAR DISEASE IN PENSIONERS OF VARIOUS PROFESSIONAL TYPES

Studies in the area of chemistry teaching discovered that problem-based learning strategies (PBL) effectively improve students’ conceptual understanding. However, there is minimal information about the effectiveness of PBL if it is applied with multiple representations (MR) for the students with different learning preferences. This study aimed to prove the effects of problem-based learning strategies (PBL) using multiple representations (MR) and students’ learning styles on the conceptual understanding in chemistry. There were two whole classes in the Mechanical Engineering Department of Bali State Polytechnic that were assigned to be the experimental group (n = 59) and control group (n = 58). Felder-Soloman's Index of Learning Style (ILS) was applied to differentiate the students’ learning preferences, while their conceptual understanding in chemistry was assessed using a test after 6 weeks of treatment. The analysis of covariance (ANCOVA) shows that the conceptual understanding of students taught using PBL strategies with MR was significantly better than those taught using PBL strategies only. Besides, based on the variation of learning styles, students with a visual style had a better conceptual understanding than those with verbal style, but the difference was not statistically significant. The absence of interaction effect between PBL strategies with MR and learning style on students’ conceptual understanding suggests that the support of multiple representations in PBL strategies can effectively enhance students' understanding of concepts in chemistry regardless of their learning style.

On how risk and group size interact to influence vigilance.

Vigilance allows animals to monitor their surroundings for signs of danger associated with predators or rivals. As vigilance is costly, models predict that it should increase when the risk posed by predators or rivals increases. In addition, vigilance is expected to decrease in larger groups that provide more safety against predators. Risk and group size are thus two key determinants of vigilance. Together, they could have additive or interactive effects. If risk and group size interacted, the magnitude of the group-size effect on vigilance would vary depending on the level of risk experienced, implying that the benefits of sociality in terms of vigilance vary with risk. Depending on the model, vigilance is predicted to decrease more rapidly with group size at low risk or at high risk. Little work has focused directly on the interaction between risk and group size, making it difficult to understand under which conditions particular interactive effects arise and whether interactive effects are common in natural systems. I review the vast literature on vigilance in birds and mammals to assess whether interactive effects between risk and group size are common, and if present, which pattern occurs more frequently. In studies involving predation risk, the greatest proportion reported no statistically significant interactive effects. In other cases, vigilance decreased with group size more rapidly at low or high risk in a similar proportion of studies. In studies involving risk posed by rivals (social risk), most documented a more rapid decrease in vigilance with group size at low than at high risk, as predicted if the need to monitor rivals increases in larger groups. Low statistical power to detect interactive effects might have been an issue in several studies. The absence of interactive effects, on the other hand, might suggest constraints or limits on the ability of animals to adjust vigilance to current risk or group sizes. Interactive effects on vigilance have implications for the evolution of sociality and for our understanding of the phenotypic plasticity of predator- and competitor-induced defences and deserve more attention in future studies.

Profiles of Language and Behavior in Students With Emotional Disturbance

Although global associations between language and behavioral development are well established, relations among components and subgroups within these disorders remain unclear. The primary aim of this study was to explore whether language components differed by behavioral subtypes: internalizing only, externalizing only, or both. To control for confounding factors identified in prior studies related to sampling and measurement, we conducted profile analyses of receptive, expressive, pragmatic, semantic, syntactic, or higher order language skills in 46 boys with emotional disturbance (ED) using one comprehensive language measure. On average, the internalizing-only group outperformed all other behavioral subgroups. Absence of interaction effects indicated similar patterns of performance, with all groups performing lowest in pragmatic language. We also report prevalence rates of language deficits in the sample and analyze results using two different grouping strategies. Discussion includes the importance of considering comorbidity and establishing independent behavioral subgroups in research, as well as implications for assessment and intervention in practice.

Interaction between feed use efficiency and level of dietary crude protein on enteric methane emission and apparent nitrogen use efficiency with Norwegian Red dairy cows1

We assessed the interactive effects of gross feed use efficiency (FUE, milk yield/kg DMI) background (“high” = HEFF vs. “low” = LEFF) and graded levels of dietary CP (130, 145, 160, and 175 g/kg DM) on milk production, enteric methane (CH4) emission, and apparent nitrogen use efficiency (NUE, g milk protein nitrogen/g nitrogen intake) with Norwegian Red (NRF) dairy cows. Eight early- to mid-lactation cows were used in a 4 × 4 Latin square design experiment (2 efficiency backgrounds, 4 dietary treatments, and 4 periods each lasting 28 d). The diets were designed to be identical in physical nature and energy density, except for the planned changes in CP, which was a contribution of slight changes in other dietary constituents. We hypothesized that HEFF cows would partition more dietary energy and nitrogen into milk components and, as such, partition less energy in the form of methane and excrete less nitrogen in urine and feces compared with their LEFF contemporaries. We observed no interactions between dietary CP level and efficiency background on DMI, other nutrient intake, NUE, CH4 emission, and its intensity (g CH4/kg milk). Gradually decreasing dietary CP from 175 to 130 g/kg DM did not affect DMI, milk and energy-corrected milk yield, and milk component yields and daily CH4 emission. However, decreasing dietary CP increased NUE and reduced urinary nitrogen (UN) excretion both in quantitative terms and as proportion of nitrogen intake. The HEFF cows showed improved NUE and decreased CH4 emission intensity compared with the LEFF cows. In the absence of interaction effects between efficiency background and dietary CP level, our results suggest that CH4 emission intensity and UN excretions can be reduced by selecting dairy cows with higher FUE and reducing dietary CP level, respectively, independent of one another. Furthermore, UN excretion predictions based on milk urea nitrogen (MUN) and cow BW for NRF cows produced very close estimates to recorded values promising an inexpensive and useful tool for estimating UN excretion under the Nordic conditions where ordinary milk analysis comes with MUN estimates.

Assessing the environmental hazard of individual and combined pharmaceuticals: acute and chronic toxicity of fluoxetine and propranolol in the crustacean Daphnia magna.

Pharmaceuticals are widespread emerging contaminants and, like all pollutants, are present in combination with others in the ecosystems. The aim of the present work was to evaluate the toxic response of the crustacean Daphnia magna exposed to individual and combined pharmaceuticals. Fluoxetine, a selective serotonin re-uptake inhibitor widely prescribed as antidepressant, and propranolol, a non-selective β-adrenergic receptor-blocking agent used to treat hypertension, were tested. Several experimental trials of an acute immobilization test and a chronic reproduction test were performed. Single chemicals were first tested separately. Toxicity of binary mixtures was then assessed using a fixed ratio experimental design. Five concentrations and 5 percentages of each substance in the mixture (0, 25, 50, 75, and 100%) were tested. The MIXTOX model was applied to analyze the experimental results. This tool is a stepwise statistical procedure that evaluates if and how observed data deviate from a reference model, either concentration addition (CA) or independent action (IA), and provides significance testing for synergism, antagonism, or more complex interactions. Acute EC50 values ranged from 6.4 to 7.8 mg/L for propranolol and from 6.4 to 9.1 mg/L for fluoxetine. Chronic EC50 values ranged from 0.59 to 1.00 mg/L for propranolol and from 0.23 to 0.24 mg/L for fluoxetine. Results showed a significant antagonism between chemicals in both the acute and the chronic mixture tests when CA was adopted as the reference model, while absence of interactive effects when IA was used.

Optimization of Polysaccharide Extraction from Polygonatum odoratum by Response Surface Methodology and Evaluation of its Antitumor Activity

This work established a microwave-assisted procedure for polysaccharide extraction from Polygonatum odoratum. Response surface methodology was used to optimize microwave-assisted extraction parameters (extraction temperature, water-to-raw material ratio, microwave power, and extraction time) by implementing a three-level, fourvariable Box–Behnken experimental design in a single-factor investigation. Three-dimensional response surfaces were plotted by Design-Expert, and result indicated the absence of interaction effects of extraction temperature and microwave power. A polysaccharide yield of approximately 17.49% was obtained under the following optimized conditions: temperature of 57°C, microwave power of 300 W, extraction time of 10 min, and water-to-raw material ratio of 23:1. The results of preliminary in vitro antitumor activity tests showed that polysaccharides derived from P. odoratum could inhibit growth of A549 cells in a dose-dependent manner. Moreover, 4-400 μg/mL of these polysaccharides exerted no significant cytotoxicity to Panc-1 cells.

GammaMAXT: a fast multiple-testing correction algorithm.

BackgroundThe purpose of the MaxT algorithm is to provide a significance test algorithm that controls the family-wise error rate (FWER) during simultaneous hypothesis testing. However, the requirements in terms of computing time and memory of this procedure are proportional to the number of investigated hypotheses. The memory issue has been solved in 2013 by Van Lishout’s implementation of MaxT, which makes the memory usage independent from the size of the dataset. This algorithm is implemented in MBMDR-3.0.3, a software that is able to identify genetic interactions, for a variety of SNP-SNP based epistasis models effectively. On the other hand, that implementation turned out to be less suitable for genome-wide interaction analysis studies, due to the prohibitive computational burden.ResultsIn this work we introduce gammaMAXT, a novel implementation of the maxT algorithm for multiple testing correction. The algorithm was implemented in software MBMDR-4.2.2, as part of the MB-MDR framework to screen for SNP-SNP, SNP-environment or SNP-SNP-environment interactions at a genome-wide level. We show that, in the absence of interaction effects, test-statistics produced by the MB-MDR methodology follow a mixture distribution with a point mass at zero and a shifted gamma distribution for the top 10 % of the strictly positive values. We show that the gammaMAXT algorithm has a power comparable to MaxT and maintains FWER, but requires less computational resources and time. We analyze a dataset composed of 106 SNPs and 1000 individuals within one day on a 256-core computer cluster. The same analysis would take about 104 times longer with MBMDR-3.0.3.ConclusionsThese results are promising for future GWAIs. However, the proposed gammaMAXT algorithm offers a general significance assessment and multiple testing approach, applicable to any context that requires performing hundreds of thousands of tests. It offers new perspectives for fast and efficient permutation-based significance assessment in large-scale (integrated) omics studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13040-015-0069-x) contains supplementary material, which is available to authorized users.

Psychological influences on customer willingness to pay and choice in automated retail settings

Purpose – The purpose of this paper is to investigate the influence of price attribute framing and factors such as urgency and perceived price fairness on customer willingness to pay (WTP) in automated retail settings. Design/methodology/approach – The authors conducted two sets of quasi-experimental scenarios surrounding vending-machine purchase decisions. The first set was analyzed with MANOVA, the second set with choice-based conjoint (CBC) analysis. Findings – When prices are framed positively (as a discount), customer WTP is higher at high published price levels than it is for unframed or negatively framed prices. The effect on WTP holds whether the reference price range is broad (few large increments) or narrow (numerous small increments). In the CBC scenarios, immediate availability of the product was most influential on choice, followed by price and brand effects. These findings held under conditions invoking both urgency and price fairness. Providing an explanation for higher prices increases perceived price fairness. Research limitations/implications – Further study might assess the presence or absence of interaction effects in the conjoint scenarios. Practical implications – Managers should consider transparency in dynamic pricing, particularly when the price change is outside the control of the firm. The conjoint scenario results also offer evidence that dynamic pricing will not impact other marketing-mix decisions for fast-moving consumer goods (FMCG) dramatically (availability at point of purchase and presence in the consumer consideration set remain strong influences on choice). Social implications – Understanding these effects on WTP could help managers manage perceptions of unfairness and optimize WTP. Originality/value – A theoretical contribution from this study is that the immediate loss/gain consideration under theories of decision making under uncertainty outweigh considerations such as scarcity urgency or perceived unfairness. Use of conjoint analysis in WTP research, study of dynamic pricing in FMCG setting.

Effects of Phenanthrene- and Metal-Contaminated Sediment on the Feeding Activity of the Harpacticoid Copepod, Schizopera knabeni

The effects of sediments contaminated with sublethal concentrations of phenanthrene (PAH) and metals (Cd, Hg, Pb) were evaluated in relation to their influence on the feeding activity of a harpacticoid copepod, Schizopera knabeni. A metal mixture (at the ratio of 5Pb:3Cd:2Hg) and Cd alone reduced grazing rates of S. knabeni feeding on (14)C-labeled microalgae. Cadmium alone and Cd combined with phenanthrene significantly decreased grazing rates of S. knabeni at Cd concentrations above 49 mg kg(-1) dry sediment. No grazing was observed in 98, 106, or 157 mg kg(-1) dry sediment Cd alone or in sediment contaminated with phenanthrene (98 mg kg(-1) dry sediment) combined with Cd at these concentrations. Phenanthrene alone also caused a significant decrease (55%) in S. knabeni grazing rates. Feeding ceased above 344 mg kg(-1) dry sediment of the metal mixture alone and combined with phenanthrene. Results were consistent with an independent effect on feeding when Cd and phenanthrene were combined. When other metals were added (Pb and Hg) to the mixture, results were consistent with an additive influence on feeding rate. Because the underlying mechanisms of toxicity for metals and PAH are probably different, our observations suggest that reductions in grazing probably did not directly contribute to the lethal effects of phenanthrene or metals. The absence of interactive effects on feeding suggests that metal-PAH interactive effects on lethality have a different underlying mechanism and that reductions in grazing probably did not directly contribute to the lethality effects of phenanthrene or metals in S. knabeni.

0135 VERBAL SELF-MONITORING IN PEOPLE AT HIGH RISK OF PSYCHOSIS

Patients with schizophrenia show severe autobiographical memory impairment, thought to reflect retrieval deficits caused by executive dysfunction. However, prior research has focused exclusively on strategic (voluntary) retrieval, and ignored involuntary retrieval resulting from automatic and associative processes, involving minimal cognitive control. We report two studies with patients diagnosed with schizophrenia (Ns = 40 and 50 respectively) comparing their impairment in involuntary versus voluntary autobiographical memory. We use two different methodologies, not previously used in schizophrenia research: a naturalistic study involving real-life data and an experimental setup. Both studies consistently showed that involuntary and voluntary autobiographical memories were similarly impaired in schizophrenia. The absence of interaction effects between group and retrieval suggests that schizophrenic patients did not benefit from memory tasks involving little retrieval effort. These findings suggest that autobiographical memory impairment in schizophrenia are not caused by problems with self-initiated voluntary retrieval, but instead likely reflect encoding or binding deficits.

Vocational Training of Unemployed Workers in Belgium

In this paper we estimate, for the 1989-93 period in Belgium, the effect of vocational classroom training on the rate of transition from unemployment. We propose a “control function” estimator accounting for variable treatment effects. In the absence of interaction effects between explanatory variables this estimator identifies treatment effects free from selection bias. A natural experiment induces exogenous sub-regional variation in the training supply. This provides over-identifying restrictions that cannot be rejected. During participation, the transition rate decreases by 23% to 30%. Afterwards it increases by 47% to 73%. Making training available for a broader population would, however, reduce the

EXPECTED TIME OF TEST AND THE ACQUISITION OF KNOWLEDGE

Summary. Subjects from four classes (two classes in physics and two classes in Dutch literature) expected to receive either a delayed test (one or two weeks later) or a test immediately after their class. For all subjects, the test was given at the same time (immediate test). Male subjects expecting an immediate test performed better than male subjects expecting a delayed test. No clear findings were obtained with female subjects. While the data were inconclusive about a hypothesis derived from information processing studies, the absence of interaction effects with various personality measurements and the data from the post‐experimental questionnaire strongly suggested the inadequacy of the goal gradient hypothesis.