bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Infrared Emissivity Coating Based on Graphene Surface-Modified Flaky Aluminum
Authors: He Lihua , Zhao Yan , Xing Liying , Liu Pinggui , Zhang Youwei , Wang Zhiyong
Published: August 2018

A low infrared emissivity coating was prepared using graphene surface-modified flaky aluminum complex powders (rGO-FAl) as fillers. The flaky aluminum powders were coated with graphene through chemical bonding. Compared with pure flaky aluminum, the Vis-NIR diffuse reflectance of rGO-FAl complex powders was significantly decreased, which was beneficial to the low glossiness of the coating. After the modification, the glossiness at 60° of the coating with 40% (mass fraction) pigments decreased from 12.8 to 6.7, while the coating maintained low infrared emissivity (0.238~0.247) at a spectral range of 8–14 μm. In the electrochemical impedance spectroscopy (EIS) measurement, at the lowest frequency, the impedance of the Al-rGO test plate was at least two orders of magnitude greater than that of the control Al test plate, and the graphene layer significantly increased the bandwidth of the maximum phase angle, which indicates a good protective effect of the ultra-thin graphene layer on metal in a corrosive environment. The coating with 40% rGO-FAl complex powders can maintain its appearance after 500 h of salt spray corrosion testing. In contrast, the color of the coating with the original aluminum powders changed after only 300 h.
Synthesis of Macroporous Magnetic Fe3O4 Microparticles Via a Novel Organic Matter Assisted Open-Cell Hollow Sphere Assembly Method
Authors: Wang Huixia , Pu Ximing , Zhou Yaquan , Chen Xianchun , Liao Xiaoming , Huang Zhongbing , Yin Guangfu
Published: August 2018

Macroporous magnetic Fe3O4 microparticles, which might act as both drug carriers and magnetocaloric media, were expected to have broad application prospects on magnetocaloric-responsively controlled drug release systems. A kind of macroporous magnetic Fe3O4 microparticle was prepared by an organic matter assisted open-cell hollow sphere (hollow sphere with holes on shell) assembly method in this study. 1-vinyl-2-pyrrolidinone (NVP) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) were selected as the template and the binder, respectively. Ferrous ions were specifically bound to carbonyl groups on NVP and were then reduced by NaBH4. The reduced irons underwent heterogeneous nucleation and grain growth to form Fe0/Fe3O4 microspheres consisting of a lot of nano-Fe0 grains, and were then assembled into Fe0/Fe3O4 microparticles wrapped by AMPS. Results indicate that NVP binding with ferrous ions can promote a self-polymerization process and the formation of Fe0/Fe3O4 microspheres, while AMPS enwrapping around the resultant microspheres can facilitate their assembly into larger aggregates. As a result, macroporous Fe3O4 microparticles composed of several open-cell hollow Fe3O4 microspheres can be obtained under a Kirkendall-controlled oxidation. Moreover, these as-prepared macroporous Fe3O4 microparticles possess a narrow particle size distribution and exhibit ferromagnetism (Ms = 66.14 emu/g, Mr = 6.33 emu/g, and Hc = 105.32 Oe). Our work, described here, would open up a novel synthesis method to assemble macroporous magnetic Fe3O4 microparticles for potential application in magnetocaloric-responsively controlled drug release systems.
Magnetite–Corrole Hybrid Nanoparticles
Authors: Pereira Rute , Trindade Tito , Barata Joana
Published: August 2018

This study describes the first example of a hybrid material comprising corrole- and silica-coated magnetite nanoparticles. Firstly, cuboid and spheroid magnetite nanoparticles were prepared using a simple hydrothermal route, followed by a silica coating. The hybrid nanoparticles were obtained by promoting a covalent link between a gallium (III)(pyridine) complex of 5,10,15-tris(pentafluorophenyl)corrole (GaPFC) and the surface of magnetite–silica core/shell nanoparticles (Fe3O4@SiO2), shaped both as cuboids and spheroids. The hybrids were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV-Vis) and transmission electron microscopy (TEM). Preliminary studies on the capacity of singlet oxygen generation of the hybrid nanoparticles showed that these have lower efficiency values when compared to the pure corrole compound.
Improving Blood Transfusion Practices in a Community Hospital Setting: Our Experience with Real-Time Clinical Decision Support
Authors: Sardar Muhammad , Azharuddin Muhammad , Subedi Ananta , Ghatage Prateek , Du Doantarang , Szallasi Arpad
Published: August 2018

There is good evidence that 50% or more of red blood cell (RBC) transfusions are unnecessary. To curtail inappropriate RBC transfusions at our hospital, real-time clinical decision support was implemented in our electronic medical record (EMR) that alerts clinicians to the patient’s most recent pretransfusion hemoglobin value upon order entry and provides Best Practice Advisory. This is a soft pop-up alert which is activated when the hemoglobin exceeds 7 g/dL. The ordering clinician can either honor (by cancelling the order) or override the alert. We studied the impact of the alert on blood utilization during a 3-month period (November 2016 to January 2017). For patients who were transfused despite the alert, a retrospective review of the medical chart was performed to determine whether or not the transfusion was clinically indicated. During the study period, 178 of the 895 RBC transfusion orders (20%) triggered the alert. After excluding duplicates, 144 orders were included in our analysis. Most of these orders (124/144, 86%) were carried out despite the alert. According to our chart review, 48% of the alert transfusions could be considered inappropriate, with hemodynamically stable, asymptomatic anemia being the leading indication. Of clinical services, orthopedic surgery had the highest rate of overriding the alert with no clinical justification (70%). The number of RBC transfusions dropped from 313.5 units per month (preintervention period) to 293.2 units per month (postintervention period)—a 6.5% decrease. Real-time clinical decision support may reduce the number of inappropriate RBC transfusions in a community hospital setting, though in our study, the decrease in blood utilization (6.5%) did not reach statistical significance.
Effect of Cryogenic Temperature on Low-Cycle Fatigue Behavior of AISI 304L Welded Joint
Authors: Oh Dongjin , Song Sangwoo , Kim Namkyu , Kim Myunghyun
Published: August 2018

The aim of this study is to investigate the low-cycle fatigue (LCF) properties of an AISI 304L welded joint based on experimental data. The influential parameters on the LCF such as the specimen thickness, strain ratio and cryogenic temperature were considered in this experimental study. In order to investigate the thickness effect on the LCF behavior, two types of specimens with thicknesses of 5 mm and 10 mm were used in an LCF test. In addition, the fatigue tests were conducted under strain control with three different strain ratios of R = −1, 0, and 0.5 at room and cryogenic temperatures. Based on the results obtained by this experimental study, no significant effect involved with the thickness and the strain ratio were observed. However, it was clearly observed that LCF performance at room temperature is lower than that at cryogenic temperature. Finally, an LCF design curve that can be used in design of the liquefied natural gas (LNG) applications is suggested.
Comparative Study of Two Aging Treatments on Microstructure and Mechanical Properties of an Ultra-Fine Grained Mg-10Y-6Gd-1.5Zn-0.5Zr Alloy
Authors: Liu Huan , Huang He , Wang Ce , Ju Jia , Sun Jiapeng , Wu Yuna , Jiang Jinghua , Ma Aibin
Published: August 2018

Developing high strength and high ductility magnesium alloys is an important issue for weight-reduction applications. In this work, we explored the feasibility of manipulating nanosized precipitates on LPSO-contained (long period stacking ordered phase) ultra-fine grained (UFG) magnesium alloy to obtain simultaneously improved strength and ductility. The effect of two aging treatments on microstructures and mechanical properties of an UFG Mg-10Y-6Gd-1.5Zn-0.5Zr alloy was systematically investigated and compared by a series of microstructure characterization techniques and tensile test. The results showed that nano γ’’ precipitates were successfully introduced in T5 peak aged alloy with no obvious increase in grain size. While T6 peak aging treatment stimulated the growth of α-Mg grains to 4.3 μm (fine grained, FG), together with the precipitation of γ’’ precipitates. Tensile tests revealed that both aging treatments remarkably improved the strengths but impaired the ductility slightly. The T5 peak aged alloy exhibited the optimum mechanical properties with ultimate strength of 431 MPa and elongation of 13.5%. This work provided a novel strategy to simultaneously improve the strength and ductility of magnesium alloys by integrating the intense precipitation strengthening with ductile LPSO-contained UFG/FG microstructure.
One-Dimensional Control System for a Linear Motor of a Two-Dimensional Nanopositioning Stage Using Commercial Control Hardware
Authors: Díaz Pérez Lucía Candela , Torralba Gracia Marta , Albajez García José Antonio , Yagüe Fabra José Antonio
Published: August 2018

A two-dimensional (2D) nanopositioning platform stage (NanoPla) is in development at the University of Zaragoza. To provide a long travel range, the actuators of the NanoPla are four Halbach linear motors. These motors present many advantages in precision engineering, and they are custom made for this application. In this work, a one-dimensional (1D) control strategy for positioning a Halbach linear motor has been developed, implemented, and experimentally validated. The chosen control hardware is a commercial Digital Motor Control (DMC) Kit from Texas Instruments that has been designed to control the torque or the rotational speed of rotative motors. Using a commercial control hardware facilitates the applicability of the developed control system. Nevertheless, it constrains the design, which needs to be adapted to the hardware and optimized. Firstly, a dynamic characterization of the linear motor has been performed. By leveraging the dynamic properties of the motor, a sensorless controller is proposed. Then, a closed-loop control strategy is developed. Finally, this control strategy is implemented in the control hardware. It was verified that the control system achieves the working requirements of the NanoPla. It is able to work in a range of 50 mm and perform a minimum incremental motion of 1 μm.
Optimization of Ultrasonic-Assisted Simultaneous Extraction of Three Active Compounds from the Fruits of Forsythia suspensa and Comparison with Conventional Extraction Methods
Authors: Fang Xinsheng , Gu Shubo , Jin Zongyuan , Hao Mingqian , Yin Zhenzhen , Wang Jianhua
Published: August 2018

An efficient ultrasonic-assisted extraction (UAE) method was developed for simultaneous extraction of three active compounds, forsythiaside A (FSA), phillyrin (PHI) and rutin (RT), from the fruits of Forsythia suspensa. The effects of various factors including a binary mixed solvent of methanol/water and ethanol/water, the pH of the solvent, particle size, temperature, solvent to material ratio, ultrasonic input power and extraction time on UAE were investigated in detail. The mass transfer mechanism of UAE using different mixed solvents was further explained by comparison with the maceration extraction method. The response surface methodology was used to optimize the experimental variables including ethanol concentration, solvent to material ratio and extraction time. The optimized conditions for the simultaneous extraction of RT, FSA and PHI were: particle size 60–80 mesh, temperature 30 °C, ultrasonic power 200 W, ethanol concentration 50%, solvent to material ratio 32 mL/g and extraction time 37 min. Compared to conventional extraction methods, UAE provided the highest extraction efficiency and offered many advantages including the reduction of solvent, temperature and time for extraction.
Self-Cleaning Properties of Electrospun PVA/TiO2 and PVA/ZnO Nanofibers Composites
Authors: Khan Muhammad Qamar , Kharaghani Davood , Ullah Sana , Waqas Muhammad , Abbasi Abdul Malik Rehan , Saito Yusuke , Zhu Chunhong , Kim Ick Soo
Published: August 2018

In this report, polyvinyl alcohol/zinoxide (PVA/ZnO) & polyvinyl alcohol/titanium dioxide (PVA/TiO2) nanofibers were manufactured in three different concentrations of ZnO and TiO2 NPs for the application of self-cleaning properties because metallic oxides, specifically ZnO & TiO2, have the properties to remove the contaminants by hydroxyl radical (OH−1), which degrades the contaminants into small molecules and finally into CO2 and H2O. Therefore, these composites were manufactured by electrospinning. The resultant nanofibers were characterized for morphology by scan electron microscopy (SEM) & transmission electron microscopy (TEM), chemical interactions by Fourier-transform infrared (FT-IR) spectra, crystalline structure by X-ray diffraction (XRD) spectra water absorbency was evaluated by water contact angle, self-cleaning by solar simulator, and thermal degradation was done by thermogravimetric analysis (TGA) for the sake of nanoparticles the content. On the base of the characterization results it was concluded that these PVA/ZnO & PVA/TiO2 nanofibers have self cleaning properties, but PVA/ZnO nanofibers have higher self-cleaning properties than PVA/TiO2 nanofibers because PVA/ZnO nanofibers have 95% self-cleaning properties, which is higher than PVA/TiO2 nanofibers.
Assessment of the Suitability of the One-Step Hydrothermal Method for Preparation of Non-Covalently/Covalently-Bonded TiO2/Graphene-Based Hybrids
Authors: Kusiak-Nejman Ewelina , Moszyński Dariusz , Kapica-Kozar Joanna , Wanag Agnieszka , Morawski Antoni W.
Published: August 2018

A hybrid nanocomposites containing nanocrystalline TiO2 and graphene-related materials (graphene oxide or reduced graphene oxide) were successfully prepared by mechanical mixing and the hydrothermal method in the high-pressure atmosphere. The presented X-ray photoelectron spectroscopy (XPS) study and quantitative elemental analysis confirm similar content of carbon in graphene oxide GO (52 wt% and 46 wt%, respectively) and reduced graphene oxide rGO (92 wt% and 98 wt%, respectively). No chemical interactions between TiO2 and GO/rGO was found. TiO2 nanoparticles were loaded on GO or rGO flakes. However, Fourier transform infrared-diffuse reflection spectroscopy (FTIR/DRS) allowed finding peaks characteristic of GO and rGO. XPS study shows that since the concentration of TiO2 in the samples was no less than 95 wt%, it was assumed that the interactions between TiO2 and graphene should not influence the lower layers of titanium atoms in the TiO2 and they occurred as Ti4+ ions. Hydrothermal treatment at 200 °C did not cause the reduction of GO to rGO in TiO2-GO nanocomposites. In general, the one-step hydrothermal method must be considered to be inefficient for preparation of chemically-bonded composites synthesized from commercially available TiO2 and unfunctionalized graphene sheets obtained from graphite powder.
Transparent and Water-Resistant Composites Prepared from Acrylic Resins ABPE-10 and Acetylated Nanofibrillated Cellulose as Flexible Organic Light-Emitting Device Substrate
Authors: Song Xueping , Yang Shuang , Liu Xiuyu , Wu Min , Li Yao , Wang Shuangfei
Published: August 2018

Acetylated nanofibrillated cellulose (ANFC)/acrylic resin ABPE-10 composite film was prepared by impregnating ABPE-10 into ANFC films under negative pressure, which can enhance properties of ANFC films by forming an interpenetrating polymer network structure between ABPE-10 and the ANFC film. The ANFC/ABPE-10 composite film met the high performance flexible organic light-emitting diode substrate requirement, even when the ANFC dosage was as high as approximately 70%. The transparency of films with different ANFC dosages significantly increased from 67% (42 µm) to 88% (45 µm), as determined by ultraviolet-visible analysis. The composite film inherited the properties of AFNC, with a low coefficient of thermal expansion and a ductile compact structure. The contact angles of ANFC films increased from 49.2° to 102.9° after dipping in ABPE-10. Additionally, the composite films had good surface smoothness and mechanical properties.
Hourly Breast Expression to Estimate the Rate of Synthesis of Milk and Fat
Authors: Kent Jacqueline C. , Gardner Hazel , Lai Ching-Tat , Hartmann Peter E. , Murray Kevin , Rea Alethea , Geddes Donna T.
Published: August 2018

Objective measurement of the rate of synthesis of breast milk and fat in breastfeeding mothers requires test-weighing of each breastfeed and the measurement of each expression from each breast over 24 h, with the collection of milk samples before and after each breastfeed and expression. We sought an abbreviated technique for measuring these rates of synthesis. Participants completed a 24-h breastfeeding milk profile, and expressed their breasts on arrival at the research room and each hour thereafter for 3 h (4 expressions). The hourly rate of milk synthesis, as measured by the yield of milk from the fourth expression, was closely related to the hourly rate of milk synthesis calculated from the 24-h milk profile. The hourly rate of fat synthesis, calculated from the fat content of small samples of the first and last milk expressed during the fourth expression, was different from the rate of fat synthesis calculated from the fat content and volumes of all the breastfeeds and expressions during the 24-h milk profile. The study confirms the use of an abbreviated technique to measure the rate of breast milk synthesis, but is not reliable as a measure of the rate of fat synthesis for an individual.
Identifiability and Reconstruction of Biochemical Reaction Networks from Population Snapshot Data
Authors: Cinquemani Eugenio
Published: August 2018

Inference of biochemical network models from experimental data is a crucial problem in systems and synthetic biology that includes parameter calibration but also identification of unknown interactions. Stochastic modelling from single-cell data is known to improve identifiability of reaction network parameters for specific systems. However, general results are lacking, and the advantage over deterministic, population-average approaches has not been explored for network reconstruction. In this work, we study identifiability and propose new reconstruction methods for biochemical interaction networks. Focusing on population-snapshot data and networks with reaction rates affine in the state, for parameter estimation, we derive general methods to test structural identifiability and demonstrate them in connection with practical identifiability for a reporter gene in silico case study. In the same framework, we next develop a two-step approach to the reconstruction of unknown networks of interactions. We apply it to compare the achievable network reconstruction performance in a deterministic and a stochastic setting, showing the advantage of the latter, and demonstrate it on population-snapshot data from a simulated example.
The Global Influence of the Seventh-Day Adventist Church on Diet
Authors: Banta Jim E. , Lee Jerry W. , Hodgkin Georgia , Yi Zane , Fanica Andrea , Sabate Joan
Published: August 2018

The emphasis on health ministry within the Seventh-day Adventist (SDA) movement led to the development of sanitariums in mid-nineteenth century America. These facilities, the most notable being in Battle Creek, Michigan, initiated the development of vegetarian foods, such as breakfast cereals and analogue meats. The SDA Church still operates a handful of food production facilities around the world. The first Battle Creek Sanitarium dietitian was co-founder of the American Dietetics Association which ultimately advocated a vegetarian diet. The SDA Church established hundreds of hospitals, colleges, and secondary schools and tens of thousands of churches around the world, all promoting a vegetarian diet. As part of the ‘health message,’ diet continues to be an important aspect of the church’s evangelistic efforts. In addition to promoting a vegetarian diet and abstinence from alcohol, the SDA church has also invested resources in demonstrating the health benefits of these practices through research. Much of that research has been conducted at Loma Linda University in southern California, where there have been three prospective cohort studies conducted over 50 years. The present study, Adventist Health Study-2, enrolled 96,194 Adventists throughout North America in 2003–2004 with funding from the National Institutes of Health. Adventist Health Studies have demonstrated that a vegetarian diet is associated with longer life and better health.
Consistent Calibration of VIRR Reflective Solar Channels Onboard FY-3A, FY-3B, and FY-3C Using a Multisite Calibration Method
Authors: Wang Ling , Hu Xiuqing , Chen Lin , He Lingli
Published: August 2018

The FengYun-3 (FY-3) Visible Infrared Radiometer (VIRR), along with its predecessor, the Multispectral Visible Infrared Scanning Radiometer (MVISR), onboard the FY-1C and FY-1D, has collected continuous daily global observations for 18 years. Achieving accurate and consistent calibration for VIRR reflective solar bands (RSBs) has been challenging, as there is no onboard calibrator and the frequency of in situ vicarious calibration is limited. In this study, a new set of reflectance calibration coefficients were derived for RSBs of the FY-3A, FY-3B, and FY-3C VIRRs using a multisite (MST) calibration method. This method is an extension of a previous MST calibration method, which relies on radiative transfer modeling over the multiple stable earth sites, and no synchronous in situ measurements are needed; hence, it can be used to update the VIRR calibration on a daily basis. The on-orbit radiometric changes of the VIRR onboard the FY-3 series were assessed based on analyses of new sets of calibration slopes. Then, all recalibrated VIRR reflectance data over Libya 4, the most frequently used stable Earth site, were compared with those provided from the Level 1B (L1B) product. Additional validation was performed by comparing the recalibrated VIRR data with those derived from radiative transfer simulations using measurements from automatic calibration instruments in Dunhuang. The results indicate that the radiometric response changes of the VIRRs onboard FY-3A and FY-3B were larger than those of FY-3C VIRR and were wavelength dependent. The current approach can provide consistent VIRR reflectances across different FY-3 satellite platforms. After recalibration, differences in top-of-atmosphere (TOA) reflectance data across different VIRRs during the whole lifetime decreased from 5–10% to less than 3%. The comparison with the automatic calibration method indicates that MST calibration shows good accuracy and lower temporal oscillations.
Toward Long-Term Aquatic Science Products from Heritage Landsat Missions
Authors: Pahlevan Nima , Balasubramanian Sundarabalan V. , Sarkar Sudipta , Franz Bryan A.
Published: August 2018

This paper aims at generating a long-term consistent record of Landsat-derived remote sensing reflectance (Rrs) products, which are central for producing downstream aquatic science products (e.g., concentrations of total suspended solids). The products are derived from Landsat-5 and Landsat-7 observations leading to Landsat-8 era to enable retrospective analyses of inland and nearshore coastal waters. In doing so, the data processing was built into the SeaWiFS Data Analysis System (SeaDAS) followed by vicariously calibrating Landsat-7 and -5 data using reference in situ measurements and near-concurrent ocean color products, respectively. The derived Rrs products are then validated using (a) matchups using the Aerosol Robotic Network (AERONET) data measured by in situ radiometers, i.e., AERONET-OC, and (b) ocean color products at select sites in North America. Following the vicarious calibration adjustments, it is found that the overall biases in Rrs products are significantly reduced. The root-mean-square errors (RMSE), however, indicate noticeable uncertainties due to random and systematic noise. Long-term (since 1984) seasonal Rrs composites over 12 coastal and inland systems are further evaluated to explore the utility of Landsat archive processed via SeaDAS. With all the qualitative and quantitative assessments, it is concluded that with careful algorithm developments, it is possible to discern natural variability in historic water quality conditions using heritage Landsat missions. This requires the changes in Rrs exceed maximum expected uncertainties, i.e., 0.0015 [1/sr], estimated from mean RMSEs associated with the matchups and intercomparison analyses. It is also anticipated that Landsat-5 products will be less susceptible to uncertainties in turbid waters with Rrs(660) > 0.004 [1/sr], which is equivalent of ~1.2% reflectance. Overall, end-users may utilize heritage Rrs products with “fitness-for-purpose” concept in mind, i.e., products could be valuable for one application but may not be viable for another. Further research should be dedicated to enhancing atmospheric correction to account for non-negligible near-infrared reflectance in CDOM-rich and extremely turbid waters.
Characterizing Near-Surface Fractured-Rock Aquifers: Insights Provided by the Numerical Analysis of Electrical Resistivity Experiments
Authors: Demirel Serdar , Roubinet Delphine , Irving James , Voytek Emily
Published: August 2018

Fractured-rock aquifers represent an important part of the groundwater that is used for domestic, agricultural, and industrial purposes. In these natural systems, the presence and properties of fractures control both the quantity and quality of water extracted, meaning that knowledge about the fractures is critical for effective water resource management. Here, we explore through numerical modeling whether electrical resistivity (ER) geophysical measurements, acquired from the Earth’s surface, may potentially be used to identify and provide information about shallow bedrock fractures. To this end, we conduct a systematic numerical modeling study whereby we evaluate the effect of a single buried fracture on ER-profiling data, examining how the corresponding anomaly changes as a function of the fracture and domain characteristics. Two standard electrode configurations, the Wenner-Schlumberger (WS) and dipole-dipole (DD) arrays, are considered in our analysis, with three different spacing factors. Depending on the considered electrode array, we find that the fracture dip angle and length will impact the resistivity anomaly curves differently, with the WS array being better adapted for distinguishing between sub-horizontal and sub-vertical fractures, but the DD array leading to larger overall anomaly magnitudes. We also find that, unsurprisingly, the magnitude of the resistivity anomaly, and thus fracture detectability, is strongly affected by the depth of overburden and its electrical resistivity, as well as the fracture aperture and contrast between the fracture and bedrock resistivities. Further research into the electrical properties of fractures, both above and below the water table, is deemed necessary.
Variations of the Snow Water Equivalent in the Ourika Catchment (Morocco) over 2000–2018 Using Downscaled MERRA-2 Data
Authors: Baba Mohamed Wassim , Gascoin Simon , Jarlan Lionel , Simonneaux Vincent , Hanich Lahoucine
Published: August 2018

The Ourika River is an important tributary of the Tensift River in the water-stressed region of Marrakesh (Morocco). The Ourika river flow is dominated by the snow melt contribution from the High Atlas mountains. Despite its importance in terms of water resources, the snow water equivalent (SWE) is poorly monitored in the Ourika catchment. Here, we used MERRA-2 data to run a distributed energy-balance snowpack model (SnowModel) over 2000–2018. MERRA-2 data were downscaled to 250-m spatial resolution using a digital elevation model. The model outputs were compared to in situ measurements of snow depth, precipitation, river flow and remote sensing observations of the snow cover area from MODIS. The results indicate that the model provides an overall acceptable representation of the snow cover dynamics given the coarse resolution of the MERRA-2 forcing. Then, we used the model output to analyze the spatio-temporal variations of the SWE in the Ourika catchment for the first time. We suggest that MERRA-2 data, which are routinely available with a delay of a few weeks, can provide valuable information to monitor the snow resource in high mountain areas without in situ measurements.
New Approach for an Easily Detachable Electric Drive Unit for Off-the-Shelf Bicycles
Authors: Roemer Felix , Mrosek Marius , Schmalfuss Simon , Lienkamp Markus
Published: August 2018

While an increasing number of electric bicycles are sold, the majority is still conventional, i.e., pedal powered.Electric bicycles could raise the share of people cycling in place of more inefficient modes of transportation. This paper investigates and proposes a new approach for an electric drive unit that can easily be attached and detached to a large majority of existing off-the-shelf bicycles to convert them into legal electric assisted bicycles (pedelecs). Different drive mechanisms were investigated and a design with a friction roller at the rear wheel showed the greatest potential. A good solution is achieved with a single unit that incorporates batteries, electronics, motors and sensors in a single enclosure to minimize the mounting time. With a fastening on the seat stay tube using a simple clamp mechanism it can assist the cyclist on most existing bicycles. The legally-required pedal detection is done with an integrated proximity sensor. A prototype is built to prove a simple and nonspecific installation and convenient usage.
Starspot Occultations in Infrared Transit Spectroscopy: The Case of WASP-52b
Authors: Bruno Giovanni , Lewis Nikole K. , Stevenson Kevin B. , Filippazzo Joseph , Hill Matthew , Fraine Jonathan D. , Wakeford Hannah R. , Deming Drake , López-Morales Mercedes , Alam Munazza K.
Published: August 2018

Stellar activity is one of the main obstacles to high-precision exoplanet observations and has motivated extensive studies in detection and characterization problems. Most efforts focused on unocculted starspots in optical transit spectrophotometry, while the impact of starspot crossings is assumed to be negligible in the near-infrared. Here, we present HST/WFC3 transit observations of the active star WASP-52, hosting an inflated hot Jupiter, which present a possible starspot occultation signal. By using this data set as a benchmark, we investigated whether the masking of the transit profile distortion or modeling it with both a starspot model and a Gaussian process affects the shape of the transmission spectrum. Different methods produced spectra with the same shape and a robust detection of water vapor, and with ≲1σ different reference radii for the planet. The solutions of all methods are in agreement and reached a similar level of precision. Our WFC3 light curve of WASP-52b hints that starspot crossings might become more problematic with JWST's higher sensitivity and complete coverage of the transit profile.
MOPSS. I. Flat Optical Spectra for the Hot Jupiters WASP-4 b and WASP-52b
Authors: May E. M. , Zhao M. , Haidar M. , Rauscher E. , Monnier J. D.
Published: August 2018

We present the first results from MOPSS, The Michigan Optical Planetary Spectra Survey, aimed at creating a database of optical planetary transmission spectra all observed, reduced, and analyzed with a uniform method for the benefit of enabling comparative exoplanet studies. We discuss our methods, and present results for our first two targets observed with the Magellan Baade 6.5 m telescope, one transit of the Hot Jupiter WASP-4b and two transits of the Hot Saturn WASP-52b. Both targets present flat, featureless spectra, corresponding to the presence of aerosols. We find that the cloud decks must begin no lower than 10−4 bar for both planets. For WASP-52b, we also consider the effects of star spots on the transmission spectrum, including unocculted spots and spots on the stellar limb influencing the light curve limb-darkening parameters. We discuss the usefulness of this program in the coming James Webb Space Telescope era.
Population Syntheses of Millisecond Pulsars from the Galactic Disk and Bulge
Authors: Gonthier Peter L. , Harding Alice K. , Ferrara Elizabeth C. , Frederick Sara E. , Mohr Victoria E. , Koh Yew-Meng
Published: August 2018

We present the results of a population synthesis of radio and γ-ray millisecond pulsars (MSPs) from the galactic disk (GD). Using 92 radio MSPs detected in 13 radio surveys and 54 Fermi MSPs detected as point sources in the first point source catalog, we establish six free parameters corresponding to the overall factor and the exponents of the period and period derivative dependence for each of the radio and γ-ray empirical luminosity models. We test three high-energy emission models described by the two-pole caustic slot-gap, outer-gap, and pair-starved polar-cap geometries. The simulated distributions of pulsar properties adequately describe the distributions of detected MSPs from the GD. We explore the γ-ray emission from groups of MSPs in globular clusters and in the galactic bulge. The simulation predicts reasonable numbers of Fermi MSPs detected in the other point source catalogs and anticipates a bright future for Fermi observations of MSPs, expecting a total of ≈170 MSP detections from the GD within 10 years. Our numbers of simulated MSPs in globular clusters are in agreement with those derived from Fermi detections. The simulation predicts that about 11,000 MSPs in the galactic bulge are required to explain the γ-ray galactic center excess.
Spectral Properties of Magnetohydrodynamic Turbulence Revealed by Polarization Synchrotron Emission with Faraday Rotation
Authors: Zhang Jian-Fu , Lazarian Alex , Xiang Fu-Yuan
Published: August 2018

We investigate how to recover the spectral properties of underlying magnetohydrodynamic (MHD) turbulence using fluctuation statistics of synchrotron polarization radiation, based on the synthetic observations. Taking spatially coincident, separated, and compounded synchrotron emission and Faraday rotation regions into account, we extract the power spectrum of synchrotron polarization intensities integrated along the line of sight. Our results demonstrate that in the short wavelength range, the power spectra reflect fluctuation statistics of the perpendicular component of turbulent magnetic fields, and the spectra at long wavelengths reveal the fluctuation of the Faraday rotation density, which is a product of the parallel component of magnetic field and thermal electron density. We find that our numerical results (in the case of spatially coincident regions) are in agreement with the analytical prediction in Lazarian & Pogosyan, and this theoretical prediction is applicable to more complicated settings, i.e., the spatially separated and compounded regions. We simulate telescopic observations that incorporate the effects of telescope angular resolution and noise, and find that statistics of underlying MHD turbulence can be recovered successfully. We expect that the technique can be applied to a variety of astrophysical environments, with existing synchrotron data cubes and a large number of forthcoming data sets from such as the LOw Frequency Array for Radio astronomy, the Square Kilometer Array, and the Five-hundred-meter Aperture Spherical radio Telescope.
Dust in the Wind: Composition and Kinematics of Galaxy Outflows at the Peak Epoch of Star Formation
Authors: Jones Tucker , Stark Daniel P. , Ellis Richard S.
Published: August 2018

Galactic-scale outflows regulate the stellar mass growth and chemical enrichment of galaxies, yet key outflow properties such as the chemical composition and mass-loss rate remain largely unknown. We address these properties with Keck/ESI echellete spectra of nine gravitationally lensed z ≃ 2–3 star-forming galaxies, probing a range of absorption transitions. Interstellar absorption in our sample is dominated by outflowing material with typical velocities of ∼−150

. Approximately 80% of the total column density is associated with a net outflow. Mass-loss rates in the low-ionization phase are comparable to or in excess of the star formation rate, with total outflow rates likely higher when accounting for ionized gas. On the order of half of the heavy element yield from star formation is ejected in the low-ionization phase, confirming that outflows play a critical role in regulating galaxy chemical evolution. Covering fractions vary and are in general non-uniform, with most galaxies having incomplete covering by the low ions across all velocities. Low-ion abundance patterns show remarkably little scatter, revealing a distinct “chemical fingerprint” of outflows. Gas-phase Si/Fe abundances are significantly supersolar ([Si/Fe] ≳ 0.4), indicating a combination of α-enhancement and dust depletion. The derived properties are comparable to the most kinematically broad, metal-rich, and depleted intergalactic absorption systems at similar redshifts, suggesting that these extreme systems are associated with galactic outflows at impact parameters conservatively within a few tens of kiloparsecs. We discuss implications of the abundance patterns in z ≃ 2–3 galaxies and the role of outflows at this epoch.
Narrow Absorption Lines Complex. II. Probing the Line-locking Signatures within the Trough-like Broad Absorption Line
Authors: Lu 陆伟 Wei-Jian 坚 , Lin 林樱 Ying-Ru 如
Published: August 2018

In this paper, we report the line-locking phenomenon of the blended narrow absorption lines (NALs) within trough-like broad absorption lines (BALs) in quasar SDSS J021740.96–085447.9 (hereafter J0217–0854). Utilizing the two-epoch spectroscopic observations of J0217–0854 from the Sloan Digital Sky Survey, we find that each of its C iv, Si iv, N v, and Lyα BAL troughs actually contain at least seven NAL systems. By splitting these BAL troughs into multiple NAL systems, we find that the velocity separations between the NAL systems are similar to their doublet splittings, with some of them matching perfectly. Cases like J0217–0854, showing line-locking signatures of NALs within BAL troughs, offer direct observational evidence for the idea that radiative forces play a significant role in driving BAL (at least for Type N BAL) outflows.
Observations of Low-frequency Radio Emission from Millisecond Pulsars and Multipath Propagation in the Interstellar Medium
Authors: Bhat N. D. R. , Tremblay S. E. , Kirsten F. , Meyers B. W. , Sokolowski M. , Straten W. van , McSweeney S. J. , Ord S. M. , Shannon R. M. , Beardsley A. , Crosse B. , Emrich D. , Franzen T. M. O. , Horsley L. , Johnston-Hollitt M. , Kaplan D. L. , Kenney D. , Morales M. F. , Pallot D. , Steele K. , Tingay S. J. , Trott C. M. , Walker M. , Wayth R. B. , Williams A. , Wu C.
Published: August 2018

Studying the gravitational-wave sky with pulsar timing arrays (PTAs) is a key science goal for the Square Kilometre Array (SKA) and its pathfinder telescopes. With current PTAs reaching sub-microsecond timing precision, making accurate measurements of interstellar propagation effects and mitigating them effectively has become increasingly important to realize PTA goals. As these effects are much stronger at longer wavelengths, low-frequency observations are most appealing for characterizing the interstellar medium (ISM) along the sight lines toward PTA pulsars. The Murchison Widefield Array (MWA) and the Engineering Development Array (EDA), which utilizes MWA technologies, present promising opportunities for undertaking such studies, particularly for PTA pulsars located in the southern sky. Such pulsars are also the prime targets for PTA efforts planned with the South African MeerKAT, and eventually with the SKA. In this paper we report on observations of two bright southern millisecond pulsars, PSR J0437−4715 and PSR J2145−0750, made with these facilities; MWA observations sampled multiple frequencies across the 80–250 MHz frequency range, while the EDA provided direct-sampled baseband data to yield a large instantaneous usable bandwidth of ∼200 MHz. Using these exploratory observations, we investigate various aspects relating to pulsar emission and ISM properties, such as spectral evolution of the mean pulse shape, scintillation as a function of frequency, chromaticity in interstellar dispersion, and flux density spectra at low frequencies. Systematic and regular monitoring observations will help ascertain the role of low-frequency measurements in PTA experiments, while simultaneously providing a detailed characterization of the ISM toward the pulsars, which will be useful in devising optimal observing strategies for future PTA experiments.
Discovery and Characterization of Superefficiency in Pulsar Wind Nebulae
Authors: Torres Diego F. , Lin Tingting
Published: August 2018

We numerically study the radiative properties of the reverberation phase of pulsar wind nebulae. Reverberation brings a significant evolution in a short period of time. We show that even the Crab Nebula, associated with the more energetic pulsar of the sample that we consider, has a period in its future time evolution where the X-ray luminosity will exceed the spin-down power at the time. In fact, all of the nebulae in our sample are expected to have a period of radio, X-ray, and GeV superefficiency, and most will also have a period of TeV superefficiency. We analyze and characterize these superefficient phases.
Glass Micro-Bubbles as Additional Thermal Insulation/Shielding for Translucent and Non-Transparent Materials
Authors: Novotný František , Prokopová Lenka , Bošová Daniela
Published: August 2018

Our research is based on innovative use of the hollow glass micro-spherical material "Glass micro-bubbles" 3MTM. We apply this material like a thin-layer additional thermal insulation/shielding for polycarbonate and steel matrices. 3 identical cargo container units with polycarbonate roof skylight are used for the research: A - without application, B - with inner application of Glass micro-bubble coating and C - with outside application of Glass micro-bubble coating.Observed parameters are translucence of daylight through layer of micro-glass bubbles on the skylight, the indoor temperature and humidity and the surface temperature of the outer and inner shell are measured.
Survivalism, collectivism and proud heritage: A study of informal arts and crafts entrepreneurship in rural Zimbabwe
Authors: Bango Sibusiswe P. , Ndiweni Esinath , Galloway Laura , Verhoeven Helen
Published: August 2018

Background: Entrepreneurship has most often been studied in the context of developed economies and results extrapolated to apply universally. This tells us little about entrepreneurship in other contexts, including in developing economy situations. In the developing world, entrepreneurship has been explored as a means of reducing poverty, but there has been little inspection of it from other perspectives. Aim: This article explores the motives and experiences of arts and crafts traders in rural Zimbabwe and provides information about the purposes of the business for financial and social life from the perspectives of our research participants. Method: The study used a qualitative methodology, conducting interviews with 12 rural arts and crafts traders. Results: The research identifies drivers, experiences and outcomes of entrepreneurship that are explained by the unique structural and sociocultural context, and the value ascribed to business refers both to financial income and the dissemination of culture and heritage. Evidence of specific sub-Saharan modes of conducting business, reflecting the collectivity, reciprocity and strong ethnic identity characteristics of sub-Saharan African societies also emerges. Conclusion: The article illustrates that western models of business and entrepreneurship may be limited in terms of informing us about the experiences in other contexts. We argue that research on entrepreneurship, and any policy on it in sub-Saharan Africa, takes cognisance of the non-western context and the potential for unique contextual business orientation and outcomes.
Expatriate mentoring: The case of a multinational corporation in Abu Dhabi
Authors: Kokt Desere , Dreyer Tommy F.
Published: August 2018

Orientation: Despite numerous studies on the adjustment challenges faced by expatriates, not much emphasis has been placed on mentoring and what mentoring plans should entail. This also pertains to research on expatriate mentoring in the United Arab Emirates (UAE), which has experienced massive economic growth and an influx of expatriates from across the globe.Research purpose: The main purpose of the study was to propose guidelines to a multinational corporation in Abu Dhabi on compiling an expatriate mentoring plan.Motivation for the study: The prevalence of expatriate assignments to the UAE and the fact that multinational companies report high failure rates served as the motivation for the study.Research approach/design and method: A mixed-method approach was followed, and a case study design was applied. A structured questionnaire was administered to 391 expatriate employees, after which principles for expatriate mentoring were formulated and presented to a focus group for discussion.Main findings: The findings show that expatriates faced challenges regarding work-related and personal-level adaptations, which emphasise the need for an expatriate mentoring plan.Practical/managerial implications: Principles for expatriate mentoring emanated from this study, namely structured interaction, clear objectives, target dates, regular reflection on challenges, formal evaluation and remedial action. These principles informed a proposed expatriate mentoring plan.Contribution/value-add: The study contributes both theoretically and empirically to the compilation of an expatriate mentoring plan.
SAND: Smart and Adaptable Networking Design Using Virtual Slicing over Software-Deﬁned Network
Authors: I. Kandah Farah , Schmitt Steven
Published: August 2018

The importance of reliable and adaptable networks has become increasingly relevant with the escalation of connectivity in our lives. The growth of streaming of entertainment and development of always online software has created an environment of large data flows that need to be handled efficiently. Historically this problem has been solved with hardware-based load-balancers. These solutions often times are expensive and lack flexibility and scalability. With the use of Software-Defined Networking, a more dynamic solution can be created to meet network load balancing needs. We propose a Smart and adaptable network design seeking to utilize network resources more efficiently by identifying traffic patterns and analyzing network metric to dynamically build virtual slices. With this design, we were able to solve the aforementioned issues through minimizing packet loss, maximizing network link utilization, and efficiently reduce the load on the controller.