Crystallization and mechanical behavior of semi-crystalline polyethylene

Molecular dynamics simulations are employed to study the crystallinity and mechanical properties of multi-chain polyethylene systems. Results show that structural composition (length and number of chains) and temperature lead to different crystallinity, which are obtained by using two general measurement methods, namely chain orientation and global order. The semi-crystalline polyethylene systems are deformed under various mechanical loading modes and at different temperatures representing different polymer states. The stretching temperature and structural composition have a strong influence on the mechanical properties, including elastic modulus, yield stress and inelastic mechanisms. The orientation crystallization caused by the heat treatment stage induces a significant direction effect on the different parts of the large-strain stress-strain response. Besides, the competition of the two main inelastic deformation mechanisms, namely shear yielding and cavitation damage, are revealed during the course of stretching.

Sustained spatial attention accounts for the direction bias of human microsaccades

Small ballistic eye movements, so called microsaccades, occur even while foveating an object. Previous studies using covert attention tasks have shown that shortly after a symbolic spatial cue, specifying a behaviorally relevant location, microsaccades tend to be directed toward the cued location. This suggests that microsaccades can serve as an index for the covert orientation of spatial attention. However, this hypothesis faces two major challenges: First, effects associated with visual spatial attention are hard to distinguish from those that associated with the contemplation of foveating a peripheral stimulus. Second, it is less clear whether endogenously sustained attention alone can bias microsaccade directions without a spatial cue on each trial. To address the first issue, we investigated the direction of microsaccades in human subjects while they attended to a behaviorally relevant location and prepared a response eye movement either toward or away from this location. We find that directions of microsaccades are biased toward the attended location rather than towards the saccade target. To tackle the second issue, we verbally indicated the location to attend before the start of each block of trials, to exclude potential visual cue-specific effects on microsaccades. Our results indicate that sustained spatial attention alone reliably produces the microsaccade direction effect. Overall, our findings demonstrate that sustained spatial attention alone, even in the absence of saccade planning or a spatial cue, is sufficient to explain the direction bias observed in microsaccades.

THE EFFECT OF FOREIGN DIRECT INVESTMENT ON TAX REVENUE IN DEVELOPING COUNTRIES

The objective of this research paper is to study the effect of Foreign Direct Investment (FDI) on tax revenue in developing countries. FDI net inflow, greenfield, and brownfield FDI are selected as the independent variable, and tax revenue and its types are chosen as the dependent variable. Using panel data analysis, this research finds that FDI net inflow has a positive correlation on total tax revenue, corporate tax revenue, individual tax revenue, and VAT revenue. However, the effect of FDI net inflow on property tax revenue is not statistically significant. This research also finds that in the developing countries, the greenfield FDI has a beneficial effect on tax revenue while brownfield FDI tend to erode tax revenue. To deal with the possibility of endogeneity problems, this research uses “political stability and absence of violence” index as an instrumental variable and conducts a two-stage least square (2SLS) regression to estimate the parameter. The result shows that FDI has a positive correlation on total tax revenue, but not significant. However, the endogeneity test shows that the endogeneity problem is less likely to exist. To conclude, FDI and tax revenue tend to have only one direction effect from FDI to tax revenue.

Is training age predictive of physiological performance changes in developmental rugby league players? A prospective longitudinal study

The aim of this study was to determine if training age – rugby league training age, resistance training age and cardiovascular training age – was predictive of changes in physiological performance in developmental rugby league players. Developmental rugby league players from one elite club ( n = 147, mean age = 15.8 ± 1.1 years) playing at Under 16 and Under 18 representative levels were tracked longitudinally over two consecutive seasons. Estimated aerobic capacity, jump height, upper body strength endurance and change of direction were assessed. Mixed method random effect analysis determined relationships between training age domains and physiological change. Positive relationships were observed between rugby league training age and change in estimated V̇O2max ( β = 0.13, p = 0.018), and change in strength endurance ( β = 0.51, p = 0.033), and resistance training age and change in jump height ( β = 0.11, p = 0.007). A negative relationship was observed between rugby league training age with change in change of direction time ( β = –0.06, p = 0.026). Moderate pre-season training effect sizes were identified for change of direction (effect size = –0.42, confidence interval (CI) = –0.8 to 0.1) and jump height (effect size = 0.41, CI = 0.1–0.7), while small pre-season training effect size was apparent for strength endurance (effect size = 0.33, CI = 0.0–0.7) and estimated V̇O2max (effect size = 0.16). Small in-season performance decrements occurred in strength endurance (effect size = –0.23, CI = –0.6 to 0.1) and change of direction (effect size = 0.30, CI = –0.1 to 0.7). Higher pre-study rugby league training age was associated with greater improvements in estimated V̇O2max, strength endurance and change of direction. Additionally, higher resistance training age was associated with greater improvements in vertical jump. Overall, the magnitude of resistance training age and cardiovascular training age may have been too inadequate to meaningfully impact training adaptations in the population. Decrease in effect size for physiological performance changes during the in-season phase suggests that performance enhancements were not maintained across the competitive season.

Is the Pollution Haven Hypothesis (PHH) valid for Turkey?

The relationship between FDI inflows and carbon dioxide (CO2) emissions is still one of the most important topics among both environmentalists and economists. In this study, the Toda-Yamamoto augmented Granger causality method is applied to analyze the relationship between FDI inflows and CO2 emissions by employing annual data from 1974 to 2011 to determine whether the pollution haven hypothesis is valid in Turkey. The results of the causality test indicated that FDI inflows and CO2 emissions have a short-run univariate causal relationship, with positive causality moving from CO2 emissions to FDI inflows. One direction effect of CO2 emissions on FDI inflows supports the pollution haven hypothesis in Turkey.

Zeolite Synthesis Using Imidazolium Cations as Organic Structure-Directing Agents

Imidazolium-derivative cations are very interesting molecules used as organic structure-directing agents (OSDAs) for zeolite synthesis, widening the possibilities of new materials and applications in this research area. In this review, the studies performed at LABPEMOL using this kind of compound are presented after a quick overview on imidazolium derivatives. The first zeolite synthesis results that started this research study were obtained with 1-butyl-3-methylimidazolium chloride. Then, the design of new OSDAs based on the imidazolium cation, such as 1,2,3-triethylimidazolium, 2-ethyl-1,3-dimethylimidazolium and 1,2,3-triethyl-4-methylimidazolium, is reported. Afterwards, the structure-direction effect caused by the introduction of heteroatoms with already-published imidazolium derivatives (for example, the Al3+ insertion into zeolite frameworks with two different OSDAs and the silicoaluminophosphate (SAPO) synthesis using 2-ethyl-1,3,4 trimethylimidazolium cations) is discussed. Finally, we also present a quick overview of some achievements of other laboratories.