Latest Articles

Open AccessArticle
Experimentally Accessible Witnesses of Many-Body Localization
Quantum Reports 2019, 1(1), 50-62; https://doi.org/10.3390/quantum1010006 (registering DOI) -
Abstract
The phenomenon of many-body localized (MBL) systems has attracted significant interest in recent years, for its intriguing implications from a perspective of both condensed-matter and statistical physics: they are insulators even at non-zero temperature and fail to thermalize, violating expectations from quantum statistical [...] Read more.
The phenomenon of many-body localized (MBL) systems has attracted significant interest in recent years, for its intriguing implications from a perspective of both condensed-matter and statistical physics: they are insulators even at non-zero temperature and fail to thermalize, violating expectations from quantum statistical mechanics. What is more, recent seminal experimental developments with ultra-cold atoms in optical lattices constituting analog quantum simulators have pushed many-body localized systems into the realm of physical systems that can be measured with high accuracy. In this work, we introduce experimentally accessible witnesses that directly probe distinct features of MBL, distinguishing it from its Anderson counterpart. We insist on building our toolbox from techniques available in the laboratory, including on-site addressing, super-lattices, and time-of-flight measurements, identifying witnesses based on fluctuations, density–density correlators, densities, and entanglement. We build upon the theory of out of equilibrium quantum systems, in conjunction with tensor network and exact simulations, showing the effectiveness of the tools for realistic models. Full article
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Open AccessArticle
Thermomechanical Characterization of SiC/SiC Ceramic Matrix Composites in a Combustion Facility
Ceramics 2019, 2(2), 407-425; https://doi.org/10.3390/ceramics2020032 (registering DOI) -
Abstract
A combustion facility which includes uniaxial mechanical loading was implemented that enables environmental conditions more akin to jet engine environments compared to conventional static environment tests. Two types of woven SiC/SiC ceramic matrix composites (CMCs), melt-infiltrated (MI) and chemical vapor infiltrated (CVI), were [...] Read more.
A combustion facility which includes uniaxial mechanical loading was implemented that enables environmental conditions more akin to jet engine environments compared to conventional static environment tests. Two types of woven SiC/SiC ceramic matrix composites (CMCs), melt-infiltrated (MI) and chemical vapor infiltrated (CVI), were subjected to fatigue loading in the combustion facility and under isothermal furnace conditions. Some CVI test coupons were coated with a multilayer environmental barrier coating (EBC) of mullite + ytterbium monosilicate using slurry infiltration process to demonstrate the performance with a coating. Combustion conditions were applied using a high velocity oxy fuel gun on the front side of the specimen and mechanical loading was applied using a horizontal hydraulic MTS machine. All the specimens considered were subjected to tension-tension fatigue loading at 100 MPa, stress ratio of 0.1 and specimen front-side surface temperature of 1200 ± 20 °C. Nondestructive evaluation (NDE) methods, such as electrical resistance (ER), was used as an in-situ health monitoring technique. Similar fatigue tests were performed in an isothermal furnace for comparison. A much lower fatigue life was observed for the uncoated specimens tested under combustion conditions in comparison to isothermal furnace condition. This difference in fatigue life was attributed to damage associated with added thermal stress due to the thermal gradient and higher rate of oxidative embrittlement due to the presence of high velocity combustion gases in the combustion environment. EBC coating increased the fatigue life in combustion environment. However, EBC coated specimens experienced spallation in the high-velocity flame due to the presence of micro cracks in the coating surface. Fracture surfaces of the failed specimens were investigated under the scanning electron microscope (SEM) to determine the extent of oxidation and damage. Full article
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Open AccessArticle
Development of an Occupational Health Safe Return to Work Prototype Application and Ergonomics Dataset for Agricultural Tasks
Safety 2019, 5(2), 40; https://doi.org/10.3390/safety5020040 -
Abstract
Serious, restrictive, non-fatal injuries are commonplace in large animal agriculture including in pork and dairy production. Primary care clinicians often have few resources to facilitate workers’ return to work and have difficulties communicating work restrictions/limitations to workers and their employers. This project developed [...] Read more.
Serious, restrictive, non-fatal injuries are commonplace in large animal agriculture including in pork and dairy production. Primary care clinicians often have few resources to facilitate workers’ return to work and have difficulties communicating work restrictions/limitations to workers and their employers. This project developed SafeReturnToWork.org, a web-based platform to aid physicians and farmers in farmworkers’ timely and safe return to work. This prototype characterizes the duties of dairy and pork workers, and facilitates the creation of applicable light duty job assemblies for farmers and farmworkers by physicians and other healthcare providers. Guided by interviews and focus groups with physicians, farmers, and farmworkers, the system was developed for use with workplace injuries that could eventually link to human resource department systems, an electronic health record, or expand to other industries beyond agriculture. Full article
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Open AccessReview
Mass Spectrometry-Based Proteomics of Fungal Pathogenesis, Host–Fungal Interactions, and Antifungal Development
J. Fungi 2019, 5(2), 52; https://doi.org/10.3390/jof5020052 (registering DOI) -
Abstract
The prevalence of fungal diseases is increasing on a global scale, ranging from acute to systemic infections caused by commensal or pathogenic microorganisms, often associated with the immune status of the host. Morbidity and mortality rates remain high and our ability to treat [...] Read more.
The prevalence of fungal diseases is increasing on a global scale, ranging from acute to systemic infections caused by commensal or pathogenic microorganisms, often associated with the immune status of the host. Morbidity and mortality rates remain high and our ability to treat fungal infections is challenged by a limited arsenal of antifungal agents and the emergence of drug resistant pathogens. There is a high demand for new approaches to elucidate the fungal mechanisms of pathogenesis and the interplay between host and pathogen to discover novel treatment options. Moreover, the need for improved drug efficacy and reduced host toxicity requires the identification and characterization of antifungal biological targets and molecular mechanisms of action. Mass spectrometry (MS)-based proteomics is a rapidly advancing field capable of addressing these priorities by providing comprehensive information on the dynamics of cellular processes, modifications, and interactions. In this Review, we focus on applications of MS-based proteomics in a diverse array of fungal pathogens and host systems to define and distinguish the molecular details of fungal pathogenesis and host–fungal interactions. We also explore the emerging role of MS-based proteomics in the discovery and development of novel antifungal therapies and provide insight into the future of MS-based proteomics in fungal biology. Full article
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Open AccessArticle
Exchange Rate Misalignment and Capital Flight from Botswana: A Cointegration Approach with Risk Thresholds
J. Risk Financial Manag. 2019, 12(2), 101; https://doi.org/10.3390/jrfm12020101 (registering DOI) -
Abstract
This study investigates the impact of exchange rate misalignment on outward capital flight in Botswana over the period 1980–2015. The study uses the autoregressive distributed lag (ARDL) approach to cointegration and the Toda and Yamamoto (1995) approach to Granger causality. Botswana’s currency misalignment [...] Read more.
This study investigates the impact of exchange rate misalignment on outward capital flight in Botswana over the period 1980–2015. The study uses the autoregressive distributed lag (ARDL) approach to cointegration and the Toda and Yamamoto (1995) approach to Granger causality. Botswana’s currency misalignment was caused by current account imbalances. The most important determinant of capital flight from Botswana is trade openness, which indicates that exportable commodities are misinvoiced leading to net capital outflows. Our main findings show that in the long-run, when the currency is overvalued, the volume of capital flight through trade misinvoicing declines and increasing foreign reserves does not reduce outward capital flight. However, when the currency is undervalued, the volume of capital flight through trade misinvoicing increases and foreign reserves reduce outward capital flight. Investors respond more to prospects of devaluation than to inflation. Botswana should tolerate overvaluation of the pula of only up to 5%. When the pula is overvalued beyond 5%, capital flight increases substantially. The government has to formulate trade regulations and monitor imported and exported commodities. Botswana should also implement capital controls to limit capital smuggling and maintain monetary autonomy. Full article
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Open AccessArticle
Effect of Thermal Processing on Carotenoids and Folate Changes in Six Varieties of Sweet Potato (Ipomoes batata L.)
Foods 2019, 8(6), 215; https://doi.org/10.3390/foods8060215 (registering DOI) -
Abstract
Carotenoids and folate are two mandatory supplying micronutrients for children or pregnant women. Inadequate intake of these two nutrients was relevant to a higher mortality of both children and pregnancies. This study is intended to investigate the thermal impact on the changes of [...] Read more.
Carotenoids and folate are two mandatory supplying micronutrients for children or pregnant women. Inadequate intake of these two nutrients was relevant to a higher mortality of both children and pregnancies. This study is intended to investigate the thermal impact on the changes of carotenoids and folate in sweet potato roots (SPRs). Carotenoids were identified by high performance liquid chromatography (HPLC) while the folate was estimated using a microbial assay. An obvious decline was observed in total carotenoids after heating. Nevertheless, the content of provitamin compound β-carotene exhibited incredible stability during steaming and α-carotene multiplied in certain varieties, evidencing that SPRs could be an efficient way for addressing Vitamin A deficiency (VAD). As for the total folate contents, two varieties were found no significant loss after thermal process while the others showed a significant decrease. The results indicated that steaming process led to generally loss of both carotenoids and folate while the α-carotene and β-carotene were well preserved. The information provided by this study might help with enhancing the food quality in processing industry and the understanding in the nutrition changes during steaming. Full article
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Open AccessFeature PaperReview
The Use of Polymers in the Flotation Treatment of Wastewater
Processes 2019, 7(6), 374; https://doi.org/10.3390/pr7060374 (registering DOI) -
Abstract
The use of flotation for the treatment of wastewaters in general, but especially for the removal of oil, grease, general organic matter, and suspended solids, is well established as a low energy process. Polyelectrolytes (PEs) can enhance performance without adding to the solids [...] Read more.
The use of flotation for the treatment of wastewaters in general, but especially for the removal of oil, grease, general organic matter, and suspended solids, is well established as a low energy process. Polyelectrolytes (PEs) can enhance performance without adding to the solids load that occurs with inorganic additives such as alum. The bridging of pollutants and the attachment of the resulting aggregates to the air-water interface can be effectively carried out with most wastewaters. Hydrophobic modification of the PEs can be useful for difficult species. It should be applied to the flotation of polyfluoroalkyl substances, for example, as they are not amenable to economical conventional treatment. Similarly, the removal of microplastic particles from sewage effluents by flotation could be enhanced. Full article
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Open AccessArticle
Impact of Fiscal Policy on Consumption and Labor Supply under a Time-Varying Structural VAR Model
Economies 2019, 7(2), 57; https://doi.org/10.3390/economies7020057 (registering DOI) -
Abstract
This paper investigates the impact of fiscal policy on private consumption and labor supply in the UK economy using time-varying parameter vector autoregression (TVP-VAR) with stochastic volatility for the period Q2 1987 to Q2 2017. It considers fiscal variables such as government expenditure [...] Read more.
This paper investigates the impact of fiscal policy on private consumption and labor supply in the UK economy using time-varying parameter vector autoregression (TVP-VAR) with stochastic volatility for the period Q2 1987 to Q2 2017. It considers fiscal variables such as government expenditure and net tax revenue and evaluates their impact on private consumption and average hours worked per week. Three sample periods were selected and two approaches were used to identify impulse responses, first taking the average of stochastic volatility over the sample period, and then allowing for sign restrictions based on contemporaneous relationships among the selected variables. The study found a negative wealth effect of public spending on private consumption and a positive effect on hours worked, as people tend to work more hours to maintain the same standard of living. Similarly, a tax shock generates negative effects on consumption but the impact on worked hours remains unclear over a three-year time horizon. These findings are almost consistent across sample periods and alternative specifications of impulse responses. This is one of only a few studies to determine the linkages between fiscal policy and the labor market using a macroeconomic framework. Full article
Open AccessArticle
An Experiment on Autoregressive and Threshold Autoregressive Models with Non-Gaussian Error with Application to Realized Volatility
Economies 2019, 7(2), 58; https://doi.org/10.3390/economies7020058 (registering DOI) -
Abstract
This article explores the fitting of Autoregressive (AR) and Threshold AR (TAR) models with
a non-Gaussian error structure. This is motivated by the problem of finding a possible probabilistic
model for the realized volatility. A Gamma random error is proposed to cater for [...] Read more.
This article explores the fitting of Autoregressive (AR) and Threshold AR (TAR) models with
a non-Gaussian error structure. This is motivated by the problem of finding a possible probabilistic
model for the realized volatility. A Gamma random error is proposed to cater for the non-negativity of
the realized volatility. With many good properties, such as consistency even for non-Gaussian errors,
the maximum likelihood estimate is applied. Furthermore, a non-gradient numerical Nelder–Mead
method for optimization and a penalty method, introduced for the non-negative constraint imposed
by the Gamma distribution, are used. In the simulation experiments, the proposed fitting method
found the true model with a rather insignificant bias and mean square error (MSE), given the true AR
or TAR model. The AR and TAR models with Gamma random error are then tested on empirical
realized volatility data of 30 stocks, where one third of the cases are fitted quite well, suggesting
that the model may have potential as a supplement for current Gaussian random error models with
proper adaptation. Full article
Open AccessArticle
Heavy Metals: Might as Well Jump
Int. J. Financial Stud. 2019, 7(2), 33; https://doi.org/10.3390/ijfs7020033 (registering DOI) -
Abstract
Financial times series, and commodity prices in particular, are known to exhibit fat tails in the distribution of prices. As with many natural resources price series, the arrival of new information can lead to unexpectedly rapid changes—or jump—in prices. This suggests that natural [...] Read more.
Financial times series, and commodity prices in particular, are known to exhibit fat tails in the distribution of prices. As with many natural resources price series, the arrival of new information can lead to unexpectedly rapid changes—or jump—in prices. This suggests that natural resource commodity prices should follow a more complex process than geometric Brownian motion (GBM), which is linked to the Gaussian distribution. The presence of jumps (discontinuities) in several heavy metal price series is investigated, as well as time-varying volatility. The results demonstrate that allowing for jumps and time-varying volatility provides statistically important improvements in the modelling or prices, relative to GBM. These complex processes contributed to the fatness of the tails in the distribution of heavy metal price returns. Full article
Open AccessArticle
Temporal, Plant Part, and Interpopulation Variability of Secondary Metabolites and Antioxidant Activity of Inula helenium L.
Plants 2019, 8(6), 179; https://doi.org/10.3390/plants8060179 (registering DOI) -
Abstract
Variations in abiotic environmental factors have significant effects on quantity and quality of secondary metabolites, which is particularly important for plant species that possess biologically active compounds. The purpose of this study is determination of the total phenolic content, flavonoid concentration, and antioxidant [...] Read more.
Variations in abiotic environmental factors have significant effects on quantity and quality of secondary metabolites, which is particularly important for plant species that possess biologically active compounds. The purpose of this study is determination of the total phenolic content, flavonoid concentration, and antioxidant activity of the different parts of Inula helenium L. (Asteraceae) sampled from different populations and in different time periods. The amounts obtained for the total phenolics varied from 16.73 to 89.85 mg of gallic acid (GA)/g. The concentration of flavonoids ranged from 9.32 to 376.22 mg of rutin (Ru)/g. The IC50 values of antioxidant activity determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical method varied from 161.60 to 1563.02 μg/ml. The inflorescence and roots possessed high concentration of phenolic compounds and significant antioxidant activity, while leaves contained the highest concentration of flavonoids. Additionally, the quantity of the phenolics, as well as antioxidant activity, significantly varied among the different populations due to different impacts of environmental factors. This research showed that I. helenium represents an abundant source of bioactive substances, and that the quantity of these compounds greatly differs among the different populations as well as in the same populations regarding the different time periods as well as plant parts. Full article
Open AccessArticle
A Segmentation-Cooperated Pansharpening Method Using Local Adaptive Spectral Modulation
Electronics 2019, 8(6), 685; https://doi.org/10.3390/electronics8060685 (registering DOI) -
Abstract
In order to improve the spatial resolution of multispectral (MS) images and reduce spectral distortion, a segmentation-cooperated pansharpening method using local adaptive spectral modulation (LASM) is proposed in this paper. By using the k-means algorithm for the segmentation of MS images, different connected [...] Read more.
In order to improve the spatial resolution of multispectral (MS) images and reduce spectral distortion, a segmentation-cooperated pansharpening method using local adaptive spectral modulation (LASM) is proposed in this paper. By using the k-means algorithm for the segmentation of MS images, different connected component groups can be obtained according to their spectral characteristics. For spectral information modulation of fusion images, the LASM coefficients are constructed based on details extracted from images and local spectral relationships among MS bands. Moreover, we introduce a cooperative theory for the pansharpening process. The local injection coefficient matrix and LASM coefficient matrix are estimated based on the connected component groups to optimize the fusion result, and the parameters of the segmentation algorithm are adjusted according to the feedback from the pansharpening result. In the experimental part, degraded and real data sets from GeoEye-1 and QuickBird satellites are used to assess the performance of our proposed method. Experimental results demonstrate the validity and effectiveness of our method. Generally, the method is superior to several classic and state-of-the-art pansharpening methods in both subjective visual effect and objective evaluation indices, achieving a balance between the injection of spatial details and maintenance of spectral information, while effectively reducing the spectral distortion of the fusion image. Full article
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