bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipidomic Analysis of the Outer Membrane Vesicles from Paired Polymyxin-Susceptible and -Resistant Klebsiella pneumoniae Clinical Isolates
Authors: Jasim Raad , Han Mei-Ling , Zhu Yan , Hu Xiaohan , Hussein Maytham H. , Lin Yu-Wei , Zhou Qi (Tony) , Dong Charlie Yao Da , Li Jian , Velkov Tony
Published: August 2018

Gram-negative bacteria produce outer membrane vesicles (OMVs) as delivery vehicles for nefarious bacterial cargo such as virulence factors, which are antibiotic resistance determinants. This study aimed to investigate the impact of polymyxin B treatment on the OMV lipidome from paired polymyxin-susceptible and -resistant Klebsiella pneumoniae isolates. K. pneumoniae ATCC 700721 was employed as a reference strain in addition to two clinical strains, K. pneumoniae FADDI-KP069 and K. pneumoniae BM3. Polymyxin B treatment of the polymyxin-susceptible strains resulted in a marked reduction in the glycerophospholipid, fatty acid, lysoglycerophosphate and sphingolipid content of their OMVs. Conversely, the polymyxin-resistant strains expressed OMVs richer in all of these lipid species, both intrinsically and increasingly under polymyxin treatment. The average diameter of the OMVs derived from the K. pneumoniae ATCC 700721 polymyxin-susceptible isolate, measured by dynamic light scattering measurements, was ~90.6 nm, whereas the average diameter of the OMVs isolated from the paired polymyxin-resistant isolate was ~141 nm. Polymyxin B treatment (2 mg/L) of the K. pneumoniae ATCC 700721 cells resulted in the production of OMVs with a larger average particle size in both the susceptible (average diameter ~124 nm) and resistant (average diameter ~154 nm) strains. In light of the above, we hypothesize that outer membrane remodelling associated with polymyxin resistance in K. pneumoniae may involve fortifying the membrane structure with increased glycerophospholipids, fatty acids, lysoglycerophosphates and sphingolipids. Putatively, these changes serve to make the outer membrane and OMVs more impervious to polymyxin attack.
Magnolol: A Neolignan from the Magnolia Family for the Prevention and Treatment of Cancer
Authors: Ranaware Abhishek , Banik Kishore , Deshpande Vishwas , Padmavathi Ganesan , Roy Nand , Sethi Gautam , Fan Lu , Kumar Alan , Kunnumakkara Ajaikumar
Published: August 2018

The past few decades have witnessed widespread research to challenge carcinogenesis; however, it remains one of the most important health concerns with the worst prognosis and diagnosis. Increasing lines of evidence clearly show that the rate of cancer incidence will increase in future and will create global havoc, designating it as an epidemic. Conventional chemotherapeutics and treatment with synthetic disciplines are often associated with adverse side effects and development of chemoresistance. Thus, discovering novel economic and patient friendly drugs that are safe and efficacious is warranted. Several natural compounds have proved their potential against this dreadful disease so far. Magnolol is a hydroxylated biphenyl isolated from the root and stem bark of Magnolia tree. Magnolol can efficiently prevent or inhibit the growth of various cancers originating from different organs such as brain, breast, cervical, colon, liver, lung, prostate, skin, etc. Considering these perspectives, the current review primarily focuses on the fascinating role of magnolol against various types of cancers, and the source and chemistry of magnolol and the molecular mechanism underlying the targets of magnolol are discussed. This review proposes magnolol as a suitable candidate that can be appropriately designed and established into a potent anti-cancer drug.
Examining the Effect of Flow Rate Ratio on Droplet Generation and Regime Transition in a Microfluidic T-Junction at Constant Capillary Numbers
Authors: Loizou Katerina , Wong Voon-Loong , Hewakandamby Buddhika
Published: August 2018

The focus of this work is to examine the effect of flow rate ratio (quotient of the dispersed phase flow rate over the continuous phase flow rate) on a regime transition from squeezing to dripping at constant capillary numbers. The effect of the flow rate ratio on the volume of droplets generated in a microfluidic T-junction is discussed, and a new scaling law to estimate their volume is proposed. Existing work on a regime transition reported by several researchers focuses on the effect of the capillary number on regime transition, and the results that are presented in this paper advance the current understanding by indicating that the flow rate ratio is another parameter that dictates regime transition. In this paper, the transition between squeezing and dripping regimes is reported at constant capillary numbers, with a transition region identified between squeezing and dripping regimes. Dripping is observed at lower flow rate ratios and squeezing at higher flow rate ratios, with a transition region between the two regimes at flow rate ratios between 1 and 2. This is presented in a flow regime map that is constructed based on the observed mechanism. A scaling model is proposed to characterise droplet volume in terms of flow rate ratio and capillary number. The effect of flow rate ratio on the non-dimensional droplet volume is presented, and lastly, the droplet volume is expressed in terms of a range of parameters, such as the viscosity ratio between the dispersed and the continuous phase, capillary number, and the geometrical characteristics of the channels.
Role of Surfactants in the Properties of Poly(Ethylene Terephthalate)/Purified Clay Nanocomposites
Authors: Dos Santos Elaine Pereira , Fook Marcus Vinícius Lia , Malta Oscar Manoel Loureiro , De Lima Silva Suédina Maria , Leite Itamara Farias
Published: August 2018

Purified clay was modified with different amounts of alkyl ammonium and phosphonium salts and used as filler in the preparation of PET nanocomposites via melt intercalation. The effect of this type of filler on morphology and thermal and mechanical properties of PET nanocomposites was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile properties, and transmission electron microscopy (TEM). The results showed that the mixture of alkyl ammonium and phosphonium salts favored the production of PET nanocomposites with intercalated and partially exfoliated morphologies with slight improvement in thermal stability. In addition, the incorporation of these organoclays tended to inhibit PET crystallization behavior, which is profitable in the production of transparent bottles.
The Formation of Nanoparticles and Their Competitive Interaction with Twins during Eutectic Si Growth
Authors: Wang Wei , Guo Fengxiang , Gai Zhigang , Zhang Tao , Tang Jianguo , Tian Xuelei , Liu Wenqing
Published: August 2018

In order to investigate the competitive interaction between nanoparticles and twin, the eutectic Si microstructures in Al–10Si (wt. %) base alloys with exclusive and combined addition of Sr and Sb are characterized by combined TEM and atom probe tomography (APT). The chemical short range order in Sb–Sb and Sb–Sr pairs is revealed by ab initio molecular dynamics simulation, which promotes the formation of clusters and nanoparticles. The coexistence of nanoparticles and twins is observed in Sb containing alloys, with a negative correlation in the corresponding number density, owing to the competitive stacking of precursors and individual atoms at the solid–liquid interface. Large size particles around 70 nm with a uniform distribution of Sr atoms are formed in Al–10Si–0.35Sb–0.015Sr (wt. %) alloys, due to the precursor aggregation and homogeneous nucleation in the droplets that nucleation are depressed. A model for the formation of nanoparticles and their interaction with twins is proposed.
An Improved Differential Evolution Algorithm for Crop Planning in the Northeastern Region of Thailand
Authors: Ketsripongsa Udompong , Pitakaso Rapeepan , Sethanan Kanchana , Srivarapongse Tassin
Published: August 2018

This research aimed to solve the economic crop planning problem, considering transportation logistics to maximize the profit from cultivated activities. Income is derived from the selling price and production rate of the plants; costs are due to operating and transportation expenses. Two solving methods are presented: (1) developing a mathematical model and solving it using Lingo v.11, and (2) using three improved Differential Evolution (DE) Algorithms—I-DE-SW, I-DE-CY, and I-DE-KV—which are DE with swap, cyclic moves (CY), and K-variables moves (KV) respectively. The algorithms were tested by 16 test instances, including this case study. The computational results showed that Lingo v.11 and all DE algorithms can find the optimal solution eight out of 16 times. Regarding the remaining test instances, Lingo v.11 was unable to find the optimal solution within 400 h. The results for the DE algorithms were compared with the best solution generated within that time. The DE solutions were 1.196–1.488% better than the best solution generated by Lingo v.11 and used 200 times less computational time. Comparing the three DE algorithms, MDE-KV was the DE that was the most flexible, with the biggest neighborhood structure, and outperformed the other DE algorithms.
An Improved Large Signal Model for 0.1 μm AlGaN/GaN High Electron Mobility Transistors (HEMTs) Process and Its Applications in Practical Monolithic Microwave Integrated Circuit (MMIC) Design in W band
Authors: Li Junfeng , Mao Shuman , Xu Yuehang , Zhao Xiaodong , Wang Weibo , Guo Fangjing , Zhang Qingfeng , Wu Yunqiu , Zhang Bing , Chen Tangsheng , Yan Bo , Xu Ruimin , Li Yanrong
Published: August 2018

An improved empirical large signal model for 0.1 µm AlGaN/GaN high electron mobility transistor (HEMT) process is proposed in this paper. The short channel effect including the drain induced barrier lowering (DIBL) effect and channel length modulation has been considered for the accurate description of DC characteristics. In-house AlGaN/GaN HEMTs with a gate-length of 0.1 μm and different dimensions have been employed to validate the accuracy of the large signal model. Good agreement has been achieved between the simulated and measured S parameters, I-V characteristics and large signal performance at 28 GHz. Furthermore, a monolithic microwave integrated circuit (MMIC) power amplifier from 92 GHz to 96 GHz has been designed for validation of the proposed model. Results show that the improved large signal model can be used up to W band.
Mediterranean Diet and Bladder Cancer Risk in Italy
Authors: Bravi Francesca , Spei Maria-Eleni , Polesel Jerry , Di Maso Matteo , Montella Maurizio , Ferraroni Monica , Serraino Diego , Libra Massimo , Negri Eva , La Vecchia Carlo , Turati Federica
Published: August 2018

Previous studies have reported that Mediterranean diet is inversely related to the risk of several neoplasms; however, limited epidemiological data are available for bladder cancer. Thus, we examined the association between Mediterranean diet and this neoplasm in an Italian multicentric case-control study consisting of 690 bladder cancer cases and 665 controls. We assessed the adherence to the Mediterranean diet via a Mediterranean Diet Score (MDS), which represents the major characteristics of the Mediterranean diet and ranges from 0 to 9 (from minimal to maximal adherence, respectively). We derived odds ratios (ORs) of bladder cancer according to the MDS score from multiple logistic regression models, allowing for major confounding factors. The ORs of bladder cancer were 0.72 (95% confidence interval, CI, 0.54–0.98) for MDS of 4–5 and 0.66 (95% CI, 0.47–0.93) for MDS of 6–9 (p for trend = 0.02) compared to MDS = 0–3. Results were similar in strata of sex, age, and education, while the risk appeared somewhat lower in never-smokers and patients with pT1–pT4 bladder carcinomas. Among individual components of the MDS, we observed inverse associations for greater consumption of legumes, vegetables, and fish. In our study, which was carried out on an Italian population, the higher adherence to the Mediterranean diet was related to a lower risk of bladder cancer.
Evaluation of Alignment between the Health Claims Nutrient Profiling Scoring Criterion (NPSC) and the Health Star Rating (HSR) Nutrient Profiling Models
Authors: Dunford Elizabeth K. , Huang Liping , Peters Sanne A. E. , Crino Michelle , Neal Bruce C. , Ni Mhurchu Cliona
Published: August 2018

In Australia, manufacturers can use two government-endorsed approaches to advertise product healthiness: the Health Star Rating (HSR) front-of-pack nutrition labelling system, and health claims. Related, but different, algorithms determine the star rating of a product (the HSR algorithm) and eligibility to display claims (the Nutrient Profiling Scoring Criterion (NPSC) algorithm). The objective of this study was to examine the agreement between the HSR and NPSC algorithms. Food composition information for 41,297 packaged products was extracted from The George Institute’s FoodSwitch database. HSR and the NPSC scores were calculated, and the proportion of products in each HSR category that were eligible to display a health claim under the NPSC was examined. The highest agreement between the HSR scoring algorithm and the NPSC threshold to determine eligibility to display a health claim was at the HSR cut-off of 3.5 stars (k = 0.83). Overall, 97.3% (n = 40,167) of products with star ratings of 3.5 or higher were also eligible to display a health claim, and 94.3% (n = 38,939) of products with star ratings less than 3.5 were ineligible to display a health claim. The food group with greatest divergence was “edible oils”, with 45% products (n = 342) with HSR >3.5, but 64% (n = 495) eligible to display a claim. Categories with large absolute numbers of products with HSR <3.5, but eligible to display a claim, were “yoghurts and yoghurt drinks” (335 products, 25.4%) and “soft drinks” (299 products, 29.7%). Categories with a large number of products with HSR ≥3.5, but ineligible to display a claim, were “milk” (260 products, 21.2%) and “nuts and seeds” (173 products, 19.7%). We conclude that there is good agreement between the HSR and the NPSC systems overall, but divergence in some food groups is likely to result in confusion for consumers, particularly where foods with low HSRs are eligible to display a health claim. The alignment of the NPSC and HSR scoring algorithms should be improved.
Prescribing Empiric Antibiotics for Febrile Neutropenia: Compliance with Institutional Febrile Neutropenia Guidelines
Authors: Naeem Doaa , Alshamrani Majed A. , Aseeri Mohammed A. , Khan Mansoor A.
Published: August 2018

Background: Febrile neutropenia (FN) is an oncologic emergency which should be treated immediately with empiric antibiotics. Different institutions observe different antibiograms and use different FN management guidelines. Our center implemented FN management guidelines for adult cancer patients in 2009. Hence, we decided to assess compliance with FN management guidelines and to describe the pattern of bacterial infections. Method: We conducted a cross-sectional study on all adult cancer patients admitted with FN. Data were collected from electronic medical records between January and December 2014. Results: One hundred FN episodes met the study inclusion criteria. The mean age of the patients was 41 ± 17 years; 52% (52 patients) were women. The most common diagnosis was lymphoma (33%). In terms of compliance to institutional FN guidelines, 55% of patients received guideline non-compliant treatment. The most common non-compliant treatment was incorrect amikacin dosing in 31% of patients, followed by incorrect vancomycin dosing in 20%, incorrect piperacillin/tazobactam dosing in 19%, inappropriate use of carbapenems in 18%, and non-compliant vancomycin use in 12% of patients. Bacterial isolates were only observed in 19% of the FN episodes. Among these 19 episodes of FN, Gram-negative pathogens were predominant and were identified in 74% of the episodes, followed by Gram-positive pathogens in 16% and polymicrobial pathogens in 10%. The mean time to defervescence was 2.21 ± 2 days. Conclusion: Our study concluded that there was a high percentage of non-compliance with our institutional FN management guidelines. We recommend following appropriate empiric antibiotic doses and indications as per institutional guidelines.
Fano Resonance Enhanced Surface Plasmon Resonance Sensors Operating in Near-Infrared
Authors: Huang Tianye , Zeng Shuwen , Zhao Xiang , Cheng Zhuo , Shum Perry Ping
Published: August 2018

In the phase-sensitivity-based surface plasmon resonance (SPR) sensing scheme, the highest phase jump usually happens at the darkness or quasi-darkness reflection point, which results in low power for detection. To overcome such a limitation, in this paper, a waveguide-coupled SPR configuration is proposed to work at near-infrared. The coupling between surface plasmon polariton (SPP) mode and photonic waveguide (PWG) mode results in electromagnetically induced transparency (EIT) and asymmetric Fano resonance (FR). Near the resonance, the differential phase between p-polarized and s-polarized incident waves experience drastic variation upon change of the surrounding refractive index. More importantly, since the FR occurs at the resonance slope of SPP mode, the corresponding phase change is accompanied with relatively high reflectivity, which is essential for signal-to-noise ratio (SNR) enhancement and power consumption reduction. Phase sensitivity up to 106 deg/RIU order with a minimum SPR reflectivity higher than 20% is achieved. The proposed scheme provides an alternative approach for high-performance sensing applications using FR.
On Fund Mapping Regressions Applied to Segregated Funds Hedging Under Regime-Switching Dynamics
Authors: Trottier Denis-Alexandre , Godin Frédéric , Hamel Emmanuel
Published: August 2018

Insurers issuing segregated fund policies apply dynamic hedging to mitigate risks related to guarantees embedded in such policies. A typical industry practice consists of using fund mapping regressions to represent basis risk stemming from the imperfect correlation between the underlying fund and its corresponding hedging instruments. The current work discusses the implications of using fund mapping regressions when the joint dynamics of the underlying and hedging assets is a regime-switching process. The potential underestimation of capital requirements stemming from the use of a fund mapping regression under such dynamics is discussed. The magnitude of the latter phenomenon is quantified through simulations calibrated on market data.
Influence of Spatial Aggregation on Prediction Accuracy of Green Vegetation Using Boosted Regression Trees
Authors: Colin Brigitte , Schmidt Michael , Clifford Samuel , Woodley Alan , Mengersen Kerrie
Published: August 2018

Data aggregation is a necessity when working with big data. Data reduction steps without loss of information are a scientific and computational challenge but are critical to enable effective data processing and information delineation in data-rich studies. We investigated the effect of four spatial aggregation schemes on Landsat imagery on prediction accuracy of green photosynthetic vegetation (PV) based on fractional cover (FCover). To reduce data volume we created an evenly spaced grid, overlaid that on the PV band and delineated the arithmetic mean of PV fractions contained within each grid cell. The aggregated fractions and the corresponding geographic grid cell coordinates were then used for boosted regression tree prediction models. Model goodness of fit was evaluated by the Root Mean Squared Error (RMSE). Two spatial resolutions (3000 m and 6000 m) offer good prediction accuracy whereas others show either too much unexplained variability model prediction results or the aggregation resolution smoothed out local PV in heterogeneous land. We further demonstrate the suitability of our aggregation scheme, offering an increased processing time without losing significant topographic information. These findings support the feasibility of using geographic coordinates in the prediction of PV and yield satisfying accuracy in our study area.
Metal Contamination Distribution Detection in High-Voltage Transmission Line Insulators by Laser-induced Breakdown Spectroscopy (LIBS)
Authors: Wang Naixiao , Wang Xilin , Chen Ping , Jia Zhidong , Wang Liming , Huang Ronghui , Lv Qishen
Published: August 2018

The fast detection of classical contaminants and their distribution on high-voltage transmission line insulators is essential for ensuring the safe operation of the power grid. The analysis of existing insulator contamination has traditionally relied on taking samples during a power cut, taking the samples back to the lab and then testing them with elemental analysis equipment, especially for sugars, bird droppings, and heavy metal particulates, which cannot be analysed by the equivalent salt deposit density (ESDD) or non-soluble deposit density (NSDD) methods. In this study, a novel method called laser-induced breakdown spectroscopy (LIBS) offering the advantages of no sample preparation, being nearly nondestructive and having a fast speed was applied for the analysis of metal contamination. Several LIBS parameters (laser energy and delay time) were optimized to obtain better resolution of the spectral data. The limit of detection (LOD) of the observed elements was obtained using a calibration curve. Compared to calibration curves, multivariate analysis methods including principal component analysis (PCA), k-means and partial least squares regression (PLSR) showed their superiority in analyzing metal contamination in insulators. Then, the elemental distribution of natural pollution was predicted using LIBS to fully capture information about the bulk elements (Na, Ni, Cu, Mn, Ca, etc.) of entire areas with PLSR. The results showed that LIBS could be a promising method for accurate direct online quantification of metal contamination in insulators.
Electricity as a Cooking Means in Nepal—A Modelling Tool Approach
Authors: Bhandari Ramchandra , Pandit Surendra
Published: August 2018

Cooking energy has an important role in energy demand of Nepal. Over the last decade, import of Liquefied Petroleum Gas (LPG) has increased by 3.3 times as an alternate cooking fuel to kerosene and firewood. The growing subsidy burden to endorse modern fuel switching from traditional energy sources and high import of LPG are challenges for sustainability and energy security. This paper analyzes the future residential cooking energy demand and its environmental and economic impacts from 2015 to 2035 using a Long-range Energy Alternative Planning System (LEAP) tool. In 2035, the LPG demand for cooking is projected to be 26.5 million GJ, 16.3 million GJ, 45.2 million GJ and 58.2 million GJ for business as usual (BAU), low growth rate (LGR), medium growth rate (MGR) and high growth rate (HGR) scenarios, respectively. To substitute LPG with electricity in the cooking sector by 2035, an additional 1207 MW, 734 MW, 2055 MW and 2626 MW hydropower installation is required for BAU, LGR, MGR and HGR scenarios, respectively. In the MGR scenario, substituting LPG with electricity could save from $21.8 million (2016) to $70.8 million (2035) each year, which could be used to develop large-scale hydropower projects in the long term.
Market Power Extended: From Foucault to Meadows
Authors: Biely Katharina , Maes Dries , Van Passel Steven
Published: August 2018

Market power is a complex matter that is approximated with quantitative indicators within economics. However, these indicators may not fully capture market power, or they may fail to identify it, although it may be present. Moreover, a quantitative approach restricts market power as a concept, impeding the ability to discuss its relationship with other concepts, such as sustainability. This paper extends the definition of market power, following Foucault’s understanding of power and the associated theoretical discussions of power from different disciplines. We extended Foucault’s work by including systems thinking to capture the importance of the prevalent system’s paradigm, which is the ultimate initiator of action. Apart from distinguishing different elements of power, we also integrate an instrumental view on the elements of power. The developed frame allows us to understand the dynamic character of power as a force that strives to maintain or ameliorate the position of the paradigm that it serves. Based on this frame, we outline how this extended understanding of power can be used to analyze market power itself, and its relation with sustainability.
Nonlinear Error Propagation Analysis of a New Family of Model-Based Integration Algorithm for Pseudodynamic Tests
Authors: Fu Bo , Jiang Huanjun , Wu Tao
Published: August 2018

Error propagation properties of integration algorithms are crucial in conducting pseudodynamic tests. The motivation of this study is to investigate the error propagation properties of a new family of model-based integration algorithm for pseudodynamic tests. To develop the new algorithms, two additional coefficients are introduced in the Chen-Ricles (CR) algorithm. In addition, a parameter—i.e., degree of nonlinearity—is applied to describe the change of stiffness for nonlinear structures. The error propagation equation for the new algorithms implemented in a pseudodynamic test is derived and two error amplification factors are deduced correspondingly. The error amplification factors for three structures with different degrees of nonlinearity are calculated to illustrate the error propagation effect. The numerical simulation of a pseudodynamic test for a two-story shear-type building structure is conducted to further demonstrate the error propagation characteristics of the new algorithms. It can be concluded from the theoretical analysis and numerical study that both nonlinearity and the two additional coefficients of the new algorithms have great influence on its error propagation properties.
Economic Vulnerability and Resilience to Natural Hazards: A Survey of Concepts and Measurements
Authors: Noy Ilan , Yonson Rio
Published: August 2018

With the shift from a hazard-centered disaster paradigm to one that places emphasis on vulnerability and resilience, disasters triggered by natural hazards have begun to be perceived as unnatural occurrences. To date, the theoretical conceptualization and empirical measures of vulnerability and resilience remain subjects of contentions. This survey of the empirical economic literature aims to describe the progress made in the conceptualization and measurement of the economic dimensions of vulnerability and resilience in the context of natural hazards, and to provide useful insights for policy-making. Economic vulnerability and economic resilience, interacting with the hazard itself, and the exposure of populations and physical assets, are considered to be critical determinants of the resulting impacts of disasters. The empirical evidence provides systematic support for the hypothesis that apart from the characteristics of the hazards, the potential for people and economies to avoid adverse impacts and their capacity to withstand and rebound from a disaster are influenced by a confluence of socio-economic factors.
Supply Chain Efficiency Measurement to Maintain Sustainable Performance in the Automobile Industry
Authors: Kim Illi , Kim Changhee
Published: August 2018

The automobile industry is set to undergo a structural transformation in the progress toward next-generation industries that involve autonomous vehicles and connected cars. Thus, supply chain management has become increasingly important for corporate competitiveness. This study aims to identify opportunities for improving supply chain performance by quantifying the impact of suppliers on the supply chain. An analysis was conducted in two phases. First, the efficiency of 139 partners that supply automobile components to the Hyundai Motor Company was measured using the Charnes–Cooper–Rhodes model, while the efficiency of Hyundai Motor Company’s 540 supply chains comprising partners, subsidiaries, and parent companies was measured using the network epsilon-based measure model. Second, the relationship between the partner efficiency and the supply chain efficiency was analyzed using the Mann–Whitney U test and the Tobit regression model. The results showed that efficient operation of partners hampers the efficiency of the total supply chain. Thus, there may be several partners that are not committed to quality improvement, while the Hyundai Motor Company seeks to promote quality management through win–win cooperation with partners. Consequently, automakers must review their partner management system, including their performance measurement and incentive systems.
Assessment of Heavy Metal Pollution in the Sediment of the Main Tributaries of Dongting Lake, China
Authors: Xu Jinying , Chen Yuwei , Zheng Lilin , Liu Baogui , Liu Jinfu , Wang Xiaolong
Published: August 2018

Heavy metal pollution in sediment is one of the most serious problems in water bodies, including rivers, which can cause secondary pollution when environmental conditions change. In this study, surface sediment samples collected from the four main tributaries of Dongting Lake (i.e., Xiangjiang River (XR), Zishui River (ZR), Yuanjiang River (YR), and Lishui River (LR)) were analyzed for concentrations of Zn, Cr, Cu, As, Cd, and Pb. The spatial distribution, source, and potential ecological risk of these metals were determined. The results suggest a great spatial heterogeneity of heavy metals in the sediment of the studied rivers. Heavy metals had highest concentrations in the sediment of XR, especially midstream and downstream. A principal component analysis (PCA) and correlation analysis indicated that Cd and As were mainly from industrial wastewater and mineral mining, Cr came from natural process and agricultural activities, and Zn and Cu potentially from both. Pb was originated from atmospheric deposition and river inflow transportation. According to the geo-accumulation index ( I g e o ), enrichment factor (EF), and risk index (RI) assessment, heavy metals pollution was highest in the sediment of XR, and Cd was the main pollutant in the sediment of XR, presenting considerable potential ecological risk. This may contribute to heavy metal pollution in Dongting Lake. This paper provides a reference for the aquatic environmental management of heavy metals in Dongting Lake area and its tributaries.
To What Degree Can the Specifics of Occurrence of Glacial Relic Betula humilis Schrank Be an Indicator of Habitat Conditions of Moderate Climate Peatlands?
Authors: Serafin Artur , Urban Danuta , Bronowicka-Mielniczuk Urszula , Szczurowska Agnieszka
Published: August 2018

Anthropogenic transformations of habitat conditions in moderate climate peatlands frequently cause a decrease in the number of sites of occurrence and the size of the population of many valuable plant species, including the boreal relic Betula humilis. The objective of this paper was an attempt to relate the specifics of the occurrence of the glacial relic Betula humilis in the peatlands of Central-Eastern Poland, which developed under moderate climate conditions, to the conditions of the natural environment identified through research into the physical and chemical parameters of the groundwater, as well as botanical research into its habitat. The study results confirm that shrub birch has a broad range of ecological tolerance to the majority of the studied factors and can therefore be an indicator of habitat transformation. Important environmental factors affecting its abundance are water relations and the contribution of calcium hydroxide and phosphorus fractions. A condition favouring the proper functioning of individuals of the studied species is TP values lower than other obtained values, in the following range: 0.08–0.32; P-PO4: 0.1; TN: 2.2–21.2; N-NH4: 0.1–0.46; DOC: 24.6–55.9 (mg·dm−3), as well as higher than average pH values, in the following range: 5.34–5.95; Ca: 5.67–28.1; Mg: 0.56–2.41 (mg·dm−3) and EC: 72.1–142.3 (µS·cm−1).
The Application of a Modified Version of the SWAT Model at the Daily Temporal Scale and the Hydrological Response unit Spatial Scale: A Case Study Covering an Irrigation District in the Hei River Basin
Authors: Wei Zheng , Zhang Baozhong , Liu Yu , Xu Di
Published: August 2018

As a well-built, distributed hydrological model, the Soil and Water Assessment Tool (SWAT) has rarely been evaluated at small spatial and short temporal scales. This study evaluated crop growth (specifically, the leaf area index and shoot dry matter) and daily evapotranspiration at the hydrological response unit (HRU) scale, and SWAT2009 was modified to accurately simulate crop growth processes and major hydrological processes. The parameters of the modified SWAT2009 model were calibrated using data on maize for seed from 5 HRUs and validated using data from 7 HRUs. The results show that daily evapotranspiration, shoot dry matter and leaf area index estimates from the modified SWAT2009 model were satisfactory at the HRU level, and the RMSE values associated with daily evapotranspiration, shoot dry matter, and leaf area index were reduced by 17.0%, 1.6%, and 71.2%, compared with SWAT2009. Thus, the influences of various optimal management practices on the hydrology of agricultural watersheds can be effectively assessed using the modified model.
Adaptation of an Existing Intake Structure Caused by Increased Sediment Level
Authors: Gabl Roman , Gems Bernhard , Birkner Florian , Hofer Bernhard , Aufleger Markus
Published: August 2018

An unexpected and massive redistribution of fine sediment in a large Alpine reservoir was triggered by a further lowering of the water level to conduct maintenance work. This caused the need of a total redesign of the existing head race intake for a high head power plant in the Austrian Alps. Two main geometry options for the trash rack support structure are compared with numerical simulations (ANSYS-CFX) as well as with a scale model test (scale 1:20). The laboratory experiment substantially benefited from the preliminary numerical investigation in respect of the location and implementation of the model boundaries. In return was the confidence in the numerics strengthened by the successful validation of the local head loss and the velocity distribution for the main operation cases. This allowed that the main inputs for the structural design and the further optimisation is conducted only with the 3D-numerical tool. The paper presents the interlaced concept as well as the main finding of the investigation, which lead to a successful adaptation of the intake structure.
NEW TESTS OF CALENDAR EFFECTS ON EQUITY AND SECURITIZED REAL ESTATE MARKETS
Authors: Hui Eddie C. M. , Kevin Chan Ka Kwan
Published: August 2018

We construct two new tests of calendar effects, apply them on 12 stock indices during 1996–2016, and compare the results with that using Hui and Chan (2016)’s method. The results show that the January and Halloween effects are significant for the four western generalized equity indices for small moving-window sizes. Furthermore, the securitized real estate indices show a greater difference in the overall calendar effect between the three methods than the general equity indices do. This study has an implication that a certain sector of the market is riskier than the whole market.
A Chemical and Kinematical Analysis of the Intermediate-age Open Cluster IC 166 from APOGEE and Gaia DR2
Authors: Schiappacasse-Ulloa J. , Tang B. , Fernández-Trincado J. G. , Zamora O. , Geisler D. , Frinchaboy P. , Schultheis M. , Dell’Agli F. , Villanova S. , Masseron T. , Mészáros Sz. , Souto D. , Hasselquist S. , Cunha K. , Smith V. V. , García-Hernández D. A. , Vieira K. , Robin A. C. , Minniti D. , Zasowski G. , Moreno E. , Pérez-Villegas A. , Lane R. R. , Ivans I. I. , Pan K. , Nitschelm C. , Santana F. A. , Carrera R. , Roman-Lopes A.
Published: August 2018

IC 166 is an intermediate-age open cluster (OC) (∼1 Gyr) that lies in the transition zone of the metallicity gradient in the outer disk. Its location, combined with our very limited knowledge of its salient features, make it an interesting object of study. We present the first high-resolution spectroscopic and precise kinematical analysis of IC 166, which lies in the outer disk with R
GC ∼ 12.7 kpc. High-resolution H-band spectra were analyzed using observations from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment survey. We made use of the Brussels Automatic Stellar Parameter code to provide chemical abundances based on a line-by-line approach for up to eight chemical elements (Mg, Si, Ca, Ti, Al, K, Mn, and Fe). The α-element (Mg, Si, Ca, and whenever available Ti) abundances, and their trends with Fe abundances have been analyzed for a total of 13 high-likelihood cluster members. No significant abundance scatter was found in any of the chemical species studied. Combining the positional, heliocentric distance, and kinematic information, we derive, for the first time, the probable orbit of IC 166 within a Galactic model including a rotating boxy bar, and found that it is likely that IC 166 formed in the Galactic disk, supporting its nature as an unremarkable Galactic OC with an orbit bound to the Galactic plane.
Robust Transiting Exoplanet Radii in the Presence of Starspots from Ingress and Egress Durations
Authors: Morris Brett M. , Agol Eric , Hebb Leslie , Hawley Suzanne L.
Published: August 2018

We typically measure the radii of transiting exoplanets from the transit depth, which are given by the ratio of cross-sectional areas of the planet and star. However, if a star has dark starspots (or bright regions) distributed throughout the transit chord, the transit depth will be biased toward smaller (larger) values, and thus the inferred planet radius will be smaller (larger) if these are unaccounted for. We reparameterize the transit light curve to account for “self-contamination” by photospheric inhomogeneities by splitting the parameter R

p
/R
⋆ into two parameters: one for the radius ratio, which controls the duration of ingress and egress, and another which measures the possibly contaminated transit depth. We show that this is equivalent to the formulation for contamination by a second star (with positive or negative flux), and that it is sensitive to time-steady inhomogeneity of the stellar photosphere. We use synthetic light curves of spotted stars at high signal-to-noise to show that the radius recovered from measurement of the ingress/egress duration can recover the true radii of planets transiting spotted stars with axisymmetric spot distributions if the limb-darkening parameters are precisely known. We fit time-averaged high signal-to-noise transit light curves from Kepler and Spitzer of 10 planets to measure the planet radii and search for evidence of spot distributions. We find that this sample has a range of measured depths and ingress durations that are self-consistent, providing no strong evidence for contamination by spots. However, there is suggestive evidence for occultation of starspots on Kepler-17, and that relatively bright regions are occulted by the planets of Kepler-412 and HD 80606. Future observations with the James Webb Space Telescope may enable this technique to yield accurate planetary radii in the presence of stellar inhomogeneities.
On Measuring the Variation of High-energy Cutoff in Active Galactic Nuclei
Authors: Zhang 张 Ji-Xian 继贤 , Wang 王俊 Jun-Xian 贤 , Zhu 朱飞 Fei-Fan 凡
Published: August 2018

The variation in the high-energy cutoff, E

c
, in active galactic nuclei (AGNs) uniquely probes the corona physics. In this work, we show that the ratio of two NuSTAR spectra (analogous to the difference-imaging technique widely used in astronomy) is uniquely useful in studying E

c
variations. The spectra ratio could directly illustrate potential E

c
variation between two spectra. By comparing with the ratio of two spectral-fitting models, it also examines the reliability of the spectral fitting measured E

c
variation. Assisted with this technique, we revisit the five AGNs in the literature (MCG-5-23-16, 3C 382, NGC 4593, NGC 5548, and Mrk 335), for which E

c
(kT

e
) variations have been claimed with NuSTAR observations. We show that the claimed E

c
variations appear inconsistent with the spectra ratios in three of them, thus they need to be revised, demonstrating the striking usefulness of spectra ratio. We present thereby improved spectral-fitting results and E

c
variations. We also report a new source with E

c
variations based on NuSTAR observations (radio galaxy 4C+74.26). We find the corona tends to be hotter when it brightens (hotter-when-brighter) in 3C 382, NGC 5548, Mrk 335, and 4C+74.27, but MCG-5-23-16 and NGC 4593 show no evidence of significant E

c
variations. Meanwhile, all six sources in this small sample appear softer when brighter. Changes in corona geometry are required to explain the observed hotter-when-brighter trends.
Time-dependent Study of a Protoplanetary Disk with a Magnetic Prandtl Number
Authors: Gholipour Mahmoud
Published: August 2018

Recent research on the exoplanets caused a particular focus on the protoplanetary disks (PPDs). The time evolution of a PPD gives us new insight on the planetary system around the central objects. Although the time dependency of a quasi-spherical disk has been considered in detail by many theoretical works, the time dependency of a PPD has not yet been fully understood. In this study, we consider the time evolution of the inner regions of a polytropic PPD with a toroidal magnetic field in the non-ideal magnetohydrodynamic regime. In this regime, we consider a magnetic Prandtl number for this disk that is the ratio of magnetic diffusivity to the viscosity. Also, we use a self-similar formalism to study the dynamical behavior of a PPD. Two variables, i.e., the independent self-similar variable (x) and dimensionless polytropic index (a), are mainly considered in the formulation of the problem. Therefore, we are able to consider both polytropic and isothermal cases in a unit formulation. The problem is solvable for small x in the isothermal case, where we obtain a new perspective on the dynamics of a PPD. Furthermore, we investigate the magnetic dissipation originated from the magnetic diffusivity, which is dependent on the magnetic Prandtl number, in the PPDs. The importance of this study is in the angular momentum transport and formation of planetesimal in a PPD.
X-Ray Line Profile Variations during Quasar Microlensing
Authors: Ledvina Lukáš , Heyrovský David , Dovčiak Michal
Published: August 2018

Observations of several gravitationally microlensed quasars in X-rays revealed variations in the profile of the iron Kα line in the course of microlensing events. We explore the effect by simulating a microlensing caustic crossing a spatially resolved model of emission from a thin accretion disk around a Kerr black hole. We demonstrate the sequence of spectral changes during the event, in particular the appearance of additional peaks and edges in the line profile due to microlensing. We trace the origin of these features to points on the disk, at which the total energy shift (g-factor) contours are tangent to the caustic. Contours tangent from the inner side of the caustic generate peaks, while those tangent from its outer side generate edges. We derive analytical shapes of the generated features and map the peak strength as a function of position of the tangent point on the disk. Since the features are determined by the positional geometry of the caustic relative to the g-factor contours, the same type of behavior can be expected in a much broader range of emission models. The sequence of line profile changes thus serves as a sensitive probe of the geometry and physics of the innermost region of the quasar accretion disk.
Star Cluster Ages in the Gaia Era
Authors: Choi Jieun , Conroy Charlie , Ting Yuan-Sen , Cargile Phillip A. , Dotter Aaron , Johnson Benjamin D.
Published: August 2018

We use the framework developed as part of the MESA Isochrones and Stellar Tracks (MIST) project to assess the utility of several types of observables in jointly measuring the age and 1D stellar model parameters in star clusters. We begin with a pedagogical overview summarizing the effects of stellar model parameters, such as the helium abundance, mass-loss efficiency, and mixing-length parameter, on observational diagnostics such as the color–magnitude diagram, mass–radius relation, and surface abundances, among others. We find that these parameters and the stellar age influence observables in qualitatively distinctive, degeneracy-breaking ways. To assess the current state of affairs, we use the recent Gaia Data Release 2 (DR2) along with data from the literature to investigate three well-studied old open clusters—NGC 6819, M67, NGC 6791—as case studies. Although there is no obvious tension between the existing observations and the MIST models for NGC 6819, there are interesting discrepancies in the cases of M67 and NGC 6791. At this time, parallax zero-point uncertainties in Gaia DR2 remain one of the limiting factors in the analysis of these clusters. With a combination of exquisite photometry, parallax distances, and cluster memberships from Gaia at the end of its mission, we anticipate precise and accurate ages for these and other star clusters in the Galaxy.
Is the spider a good biological control agent for Plutella xylostella (Lepidoptera: Plutellidae)?
Authors: Huang Xuan , Quan Xiaoyu , Wang Xia , Yun Yueli , Peng Yu
Published: August 2018

Spiders, as predators of insects and other invertebrates, are an important part of the natural enemies, and they are recognized as an important biological control agent. Plutellaxylostella (Linnaeus, 1758), the diamondback moth (DBM), is a well-known and destructive insect pest of brassicaceous crops worldwide. Here, we analyzed the functional responses of four spiders (Araneae) – Ebrechtellatricuspidata (Fabricius, 1775) (Thomisidae), Pardosalaura (Karsch, 1879) (Lycosidae), Pardosaastrigera (Koch, 1878) (Lycosidae), and Pardosapseudoannulata (Bösenberg & Strand, 1906) (Lycosidae) – on P.xylostella larvae. We also analyzed intraspecific disturbances in the predation reaction and the intensity of scrambling competition of the spiders to P.xylostella larvae. Our results demonstrated that the functional responses of four spiders of different genera were in line with the Holling II model. Two Lycosidae spiders (P.astrigera and P.pseudoannulata) had the potential to control P.xylostella, and female and male spiders that belonged to the same species had different functional responses to P.xylostella. The functional responses of female predation of P.astrigena, P.laura, and P.pseudoannulata was stronger than the males, but male E.tricuspidatus had stronger functional responses to predation than females. We used the Hassell model to describe the intraspecific disturbance experiments of four spiders. There were intraspecific disturbances in the predation reactions of spiders, indicating that the predation ratio of spiders decreased in relation to the increase of its density, and with the increase of spider density, the intensity of scrambling competition of the spider increased.