bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cobalt‐Tungsten‐Boron as an Active Electrocatalyst for Water Electrolysis
Authors: Cao Guo‐Xuan , Xu Ning , Chen Zheng‐Jun , Kang Qing , Dai Hong‐Bin , Wang Ping 
Published: July 2017

AbstractElectrochemically splitting water to produce clean hydrogen fuel requires high‐performance electrocatalysts. Here, we report transition metal‐boron alloy Co‐W−B is an active electrocatalyst for water electrolysis. The Co‐W−B catalyst can be readily deposited on nickle foam (NF) using a simple electroless plating method. A combination of phase/chemical state/microstructural analyses of the Co‐W−B electrocatalyst was conducted using XRD, TEM, Raman spectroscopy and XPS techniques. The properly annealed Co‐W−B/NF catalyst with an optimal composition exhibits a low overpotential along with a high stability for the hydrogen evolution reaction (HER) in alkaline solution, which is among the best reported levels for non‐noble HER catalysts. In addition, the Co‐W−B/NF catalyst also shows moderate activity towards the oxygen evolution reaction (OER). These study results highlight the potential of transition metal‐boron alloys as high‐performance and low‐cost electrocatalyst for water splitting.
Slicing the pie: how big could carbon dioxide removal be?
Authors: Psarras Peter , Krutka Holly , Fajardy Mathilde , Zhang Zhiqu , Liguori Simona , Dowell Niall Mac , Wilcox Jennifer 
Published: July 2017

The current global dependence on fossil fuels to meet energy needs continues to increase. If a 2°C warming by 2100 is to be prevented, it will become important to adopt strategies that not only avoid CO2 emissions but also allow for the direct removal of CO2 from the atmosphere, enabling the intervention of climate change. The primary direct removal methods discussed in this review include land management and mineral carbonation in addition to bioenergy and direct air capture with carbon capture and reliable storage. These methods are discussed in detail, and their potential for CO2 removal is assessed. The global upper bound for annual CO2 removal was estimated to be 12, 10, 6, and 5 GtCO2/year for bioenergy with carbon capture and reliable storage (BECCS), direct air capture with reliable storage (DACS), land management, and mineral carbonation, respectively—giving a cumulative value of ~35 GtCO2/year. However, in the case of DACS, global data on the overlap of low‐emission energy sources and reliable CO2 storage opportunities—set as a qualification for DAC viability—were unavailable, and the potential upper bound estimate is thus considered conservative. The upper bounds on the costs associated with the direct CO2 removal methods varied from approximately $100/tCO2 (land management, BECCS, and mineral carbonation) to $1000/tCO2 for DACS (again, these are the upper bounds for costs). In this review, these direct CO2 removal technologies are found to be technically viable and are potentially important options in preventing 2°C warming by 2100. WIREs Energy Environ 2017, 6:e253. doi: 10.1002/wene.253This article is categorized under:

Bioenergy > Climate and Environment
Energy and Climate > Climate and Environment
Energy and Development > Climate and Environment
Indexing ages of antelope jackrabbits and other Leporids using x‐ray
Authors: Altemus Maria M. , Babb Randall D. , Brown David E. , Cataldo Lynne , Heffelfinger Jim , Klima Karen , O'Brien James , Mulligan Grant 
Published: July 2017

ABSTRACTThe ability to determine wildlife age classes is important for wildlife management and the key to understanding the life histories of species. We used radiograph images of the epiphyseal cartilage at the distal end of the radius and the age‐class criteria developed by Lechleitner (1959) for black‐tailed jackrabbits (Lepus californicus) to determine age classes for antelope jackrabbits (L. alleni) between 2011–2016. Using 2 known‐age antelope jackrabbits, we found that 3 developmental phases similar to those identified by Lechleitner (1959; class 1 [juvenile: <7 months], class 2 [subadult: 7–11.4 months], and class 3 [adult: >11.4 months]) were also applicable to radiographs of forelegs of antelope jackrabbits. Although requiring some interpretive experience, we consider this technique superior to other lagomorph aging methods because radiographs can be obtained from live and dead animals. Using this method, biologists can determine ages of individuals in the population, which would help to estimate recruitment rates and predict population changes. © 2017 The Wildlife Society.
Dissolved organic carbon (DOC) input to the soil: DOC fluxes and their partitions during the growing season in a cool‐temperate broad‐leaved deciduous forest, central Japan
Authors: Chen Siyu , Yoshitake Shinpei , Iimura Yasuo , Asai Chiyuki , Ohtsuka Toshiyuki 
Published: July 2017

AbstractDissolved organic carbon (DOC) plays an important role in C cycling in forest ecosystems. Here we measured the concentrations and fluxes of DOC in a cool‐temperate broad‐leaved deciduous forest (Takayama Forest) to quantify the contribution of DOC from different forest water flux conditions. Mean DOC concentration during the growing season increased in the sequence from bulk precipitation (2.98 ± 0.45 mg L−1), throughfall above dwarf bamboo (6.84 ± 0.45 mg L−1), throughfall below dwarf bamboo (7.08 ± 0.42 mg L−1), stemflow (15.05 ± 0.98 mg L−1), and litter leachate (21.33 ± 1.01 mg L−1). Litter leachate DOC concentration, being high in spring and autumn, which was fairly correlated with the amount of litterfall of bamboo and trees. In stemflow, the DOC concentration was high during early summer and gradually decreased, in addition, it also showed dramatic variation among different plant species. Litter leachate (72.5%) accounted for most of the DOC input to the soil during the growing season (311.5 kg C ha−1 7 months−1), while stemflow (1.6%) contributed the least. A great quantity of precipitation at the study site was associated with a subsequent high atmospheric contribution of DOC flux (8.6%), which was more than half of throughfall (16.5%). The high input of DOC to the soil and andisol soil characteristics at the Takayama Forest suggest that the DOC fluxes are vital to the soil carbon sequestration. Therefore, DOC fluxes should be taken into account when the carbon balance is assessed at forest ecosystems.
The influence of residual apixaban on bleeding complications during and after catheter ablation of atrial fibrillation
Authors: Mukai Yutaro , Wada Kyoichi , Miyamoto Koji , Nakagita Kazuki , Fujimoto Mai , Hosomi Kouichi , Kuwahara Takeshi , Takada Mitsutaka , Kusano Kengo , Oita Akira 
Published: July 2017

AbstractBackgroundThe periprocedural protocol for atrial fibrillation (AF) ablation commonly includes anticoagulation therapy. Apixaban, a direct oral anticoagulant, is currently approved for clinical use; however, little is known about the effects of residual apixaban concentration on bleeding complications during/after AF ablation. Therefore, we measured residual apixaban concentration by using mass spectrometry and examined the anticoagulant's residual effects on bleeding complications.MethodsFifty‐eight patients (Mean age of 64.7±12.5 years; 31 males, 27 females) were enrolled and administered apixaban twice daily. We analyzed trough apixaban concentration, activated clotting time (ACT), heparin dose, and bleeding complications during/after AF ablation. Apixaban concentrations were directly measured using mass spectrometry.ResultsBleeding complications were observed in 19 patients (delayed hemostasis at the puncture site, 16; hematuria, 3; hemosputum, 1). No patient required blood transfusion. The mean trough apixaban concentration was significantly lower in patients with bleeding complications than without (152.4±73.1 vs. 206.8±98.8 ng/mL respectively, P=0.037), while the heparin dose to achieve ACT>300 s was significantly higher in patients with bleeding complications (9368.4±2929.0 vs. 7987.2±2135.2 U/body respectively, P=0.046). Interestingly, a negative correlation was found between the trough apixaban concentration and the heparin dose to achieve ACT>300 s (P=0.033, R=‐0.281).ConclusionsLow residual plasma apixaban is associated with a higher incidence of bleeding complications during/after AF ablation, potentially because of a greater heparin requirement during AF ablation.
Low Plasma Testosterone is Associated with Elevated Cardiovascular Disease Biomarkers
Authors: Pastuszak Alexander W. , Kohn Taylor P. , Estis Joel , Lipshultz Larry I. 
Published: July 2017

Abstract

Background
The relation between testosterone (T) plasma concentration and cardiovascular (CV) risk is unclear, with evidence supporting increased risk in men with low and high T levels. Few studies have assessed CV risk as a function of plasma T levels using objective biomarkers.

Aim
To determine the relation between T levels and high-sensitivity CV risk biomarkers.

Methods
Ten thousand forty-one male patients were identified in the database of a commercial clinical laboratory performing biomarker testing. Patients were grouped by total T concentration and associations with the following biomarkers were determined: cardiac troponin I (cTnI), endothelin-1 (ET-1), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-17A, N-terminal pro–B-type natriuretic peptide (NTproBNP), high-density lipoprotein (HDL) cholesterol, high-sensitivity C-reactive protein (hs-CRP), hemoglobin A1c (HbA1c), and leptin.

Outcomes
Association of CV risk markers with levels of T in men.

Results
The median age of the cohort was 58 years (interquartile range = 48–68), and the median plasma T level was 420 ng/dL (interquartile range = 304–565); T levels did not vary with patient age. An inverse relation between plasma T levels and CV risk was observed for 9 of 10 CV markers: cTnI, ET-1, IL-6, TNF-α, NTproBNP, HDL cholesterol, hs-CRP, HbA1c, and leptin. Even after adjusting for age, body mass index, HbA1c, hs-CRP, and HDL cholesterol levels, the CV markers IL-6, ET-1, NTproBNP, and leptin were significantly associated with a T level lower than 250 ng/dL.

Clinical Implications
Men with low T levels could be at increased risk for increased CV disease as seen by increased CV risk markers.

Strength and Limitations
This study was performed in a group of 10,041 men and is the first study to examine CV risk associated with circulating T levels using a large panel of 10 objective biomarkers. This study is limited by an absence of clinical data indicating whether men had pre-existing CV disease or other CV risk factors.

Conclusion
Men with low plasma T levels exhibit increases in CV risk markers, consistent with a potential increased risk of CV disease.
The contribution of fish studies to the “number sense” debate
Authors: Agrillo Christian , Bisazza Angelo 
Published: July 2017

AbstractLeibovich et al. propose that number sense is not innate but gradually emergent during ontogeny following experience. We argue that this hypothesis cannot be reasonably tested in humans, in which the contribution of neural maturation and experience cannot be experimentally manipulated. Studies on animals, especially fish, can more effectively provide critical insights into the innate nature of numerical abilities.
Multitudes are adaptable magnitudes in the estimation of number
Authors: Durgin Frank H. 
Published: July 2017

AbstractVisual number comparison does not require participants to choose a unit, whereas units are fundamental to the definition of number. Studies using magnitude estimation rather than comparison show that number perception is compressed dramatically past about 20 units. Even estimates of 5–20 items are increasingly susceptible to effects of visual adaptation, suggesting a rather narrow range in which subitizing-like categorization processes blend into greater reliance on adaptable magnitude information.
Selecting the model that best fits the data
Authors: van Woerkom Willemijn , Zuidema Willem 
Published: July 2017

AbstractLeibovich et al. argue that that none of the experiments they review really establishes that human adults, infants, or nonhuman animals are sensitive to numerosity independent of a range of continuous quantities. We do not dispute their claim that the empirical record is inconclusive but argue that model-based data analysis does offer a way to make progress.
The quest for magnetic massive stars in the Magellanic Clouds
Authors: Nazé Y. , Bagnulo S. , Walborn N. R. , Morrell N. , Wade G. A. , Szymanski M. K. , Townsend R. H. D. 
Published: July 2017

AbstractThe Of?p category was introduced more than 40 years ago to gather several Galactic stars with some odd properties. Since 2000, spectropolarimetry, high-resolution spectroscopy, long-term photometry, and X-ray observations have revealed their nature: magnetic oblique rotators - they all have magnetic fields that confine their winds. Several Of?p stars have now been detected in the Magellanic Clouds, likely the prototypes of magnetic massive stars at low metallicity. This contribution will present the most recent photometric, spectroscopic, and spectropolarimetric data, along with the first modeling of these objects.
X-rays from colliding winds in massive binaries
Authors: Nazé Yaël , Rauw Gregor 
Published: July 2017

AbstractIn a massive binary, the strong shock between the stellar winds may lead to the generation of bright X-ray emission. While this phenomenon was detected decades ago, the detailed study of this emission was only made possible by the current generation of X-ray observatories. Through dedicated monitoring and observations at high resolution, unprecedented information was revealed, putting strong constraints on the amount and structure of stellar mass-loss.
Disentangling rotational velocity distribution of stars
Authors: Curé Michel , Rial Diego F. , Cassetti Julia , Christen Alejandra 
Published: July 2017

AbstractRotational speed is an important physical parameter of stars: knowing the distribution of stellar rotational velocities is essential for understanding stellar evolution. However, rotational speed cannot be measured directly and is instead the convolution between the rotational speed and the sine of the inclination angle vsin(i). The problem itself can be described via a Fredhoml integral of the first kind. A new method (Curé et al. 2014) to deconvolve this inverse problem and obtain the cumulative distribution function for stellar rotational velocities is based on the work of Chandrasekhar & Münch (1950). Another method to obtain the probability distribution function is Tikhonov regularization method (Christen et al. 2016). The proposed methods can be also applied to the mass ratio distribution of extrasolar planets and brown dwarfs (in binary systems, Curé et al. 2015).For stars in a cluster, where all members are gravitationally bounded, the standard assumption that rotational axes are uniform distributed over the sphere is questionable. On the basis of the proposed techniques a simple approach to model this anisotropy of rotational axes has been developed with the possibility to “disentangling” simultaneously both the rotational speed distribution and the orientation of rotational axes.
Mass-ejection events in Be stars triggered by coupled nonradial pulsation modes
Authors: Baade D. , Rivinius Th. , Pigulski A. , Carciofi A. ,   BEST
Published: July 2017

AbstractBe stars (for an in-depth review see Rivinius, Carciofi & Martayan 2013) rotate at ⩾80% of the critical velocity and are multi-mode nonradial pulsators. Magnetic dipole fields are not detected, and binaries with periods less than 30 days are rare. The name-giving emission lines form in a Keplerian decretion disk, which is viscously re-accreted and also radiatively ablated unless replenished by outburts of unknown origin.Months-long, high-cadence space photometry with the BRITE-Constellation nanosatellites (Pablo et al. 2016) of about 10 early-type Be stars reveals the following (cf. Baade et al. 2016a, Baade et al. 2016b):
○Many Be stars exhibit 1 or 2 so-called Δ frequencies, which are differences between two nonradial-pulsation (NRP) frequencies and much lower (mostly less than 0.1 c/d) than the parent frequencies. The associated light curves are roughly sinusoidal. The amplitudes can exceed that of the sum of the parent amplitudes.○Conventional beat patterns also occur.○Amplitudes of both Δ and beat frequencies can temporarily be enhanced. Around phases of maximal amplitude the mean brightness is in- or decreased, and the scatter can be enhanced.○During high-activity phases (outbursts), broad and dense groups of numerous spikes arise in the power spectra. The two strongest groups often have a frequency ratio near 2. The phase coherence seems to be low.○Time coverage (less than half a year) is not yet sufficient to infer whether two Δ or beat frequencies can combine to cause long-lasting (years) superoutbursts (cf. Carciofi et al. 2012).From these observations it is concluded:
•The variable mean brightness and the increased Δ-frequency amplitude and scatter trace the amount of near-circumstellar matter.•Increase or decrease of mean brightness is aspect-angle dependent (pole-on vs. equator-on).•Increased amounts of near-circumstellar matter are due to rotation-assisted mass ejections caused by coupled NRP modes.•Observations do not constrain the location of the coupling (atmosphere or stellar interior).•Broad frequency groups do not represent stellar pulsation modes but circumstellar variability.•Be stars later than B5 are less active and may in some cases even behave differently.
The formation of Wolf-Rayet stars in the SMC is not dominated by mass transfer
Authors: Shenar Tomer , Hainich R. , Todt H. , Sander A. , Hamann W.-R. , Moffat A. , Eldridge J. J. , Pablo H. , Oskinova L. , Richardson N. 
Published: July 2017

AbstractWe analyzed spectra of all Wolf-Rayet stars in the Small Magellanic Cloud (SMC). We find that, unlike predicted, mass-transfer in binaries is not needed to explain their formation.
Testing the Wind-shock Paradigm for B-Type Star X-Ray Production with θ Car
Authors: Doyle T. F. , Petit V. , Cohen D. , Leutenegger M. 
Published: July 2017

AbstractWe present Chandra X-ray grating spectroscopy of the B0.2V star, θ Carina. θ Car is in a critical transition region between the latest O-type and earliest B-type stars, where some stars are observed to have UV-determined wind densities much lower than theoretically expected (e.g., Marcolino et al. 2009). In general, X-ray emission in this low-density wind regime should be less prominent than for O-stars (e.g., Martins et al. 2005), but observations suggest a higher than expected X-ray emission filling factor (Lucy 2012; Huenemoerder et al. 2012); if a larger fraction of the wind is shock-heated, it could explain the weak UV wind signature seen in weak wind stars, but this might severely challenge predictions of radiatively-driven wind theory.We measured the line widths of several He-, H-like and Fe ions and the f/i ratio of He-like ions in the X-ray spectrum, which improves upon the results from Nazé et al. (2008) (XMM-Newton RGS) with additional measurements (Chandra HETG) of Mgxi and Sixiii by further constraining the X-ray emission location. The f/i ratio is modified by the proximity to the UV-emitting stellar photosphere, and is therefore a diagnostic of the radial location of the X-ray emitting plasma. The measured widths of X-ray lines are narrow, <300 km s−1 and the f/i ratios place the X-rays relatively close to the surface, both implying θ Car is a weak wind star. The measured widths are also consistent with other later-type stars in the weak wind regime, β Cru (Cohen et al. 2008), for example, and are smaller on average than earlier weak wind stars such as μ Col (Huenemoerder et al. 2012). This could point to a spectral type divide, where one hypothesis, low density, works for early-B type stars and the other hypothesis, a larger fraction of shock-heated gas, explains weak winds in late-O type stars. Archival IUE data still needs to be analyzed to determine the mass loss rate and hydrodynamical simulations will be compared with observations to determine which hypothesis works for θ Car.
Proper Motions of η Carinae’s Outer Ejecta and Its Eruptive History
Authors: Kiminki Megan M. , Reiter Megan , Smith Nathan 
Published: July 2017

Abstractη Carinae, the most extreme luminous blue variable in our Galaxy, underwent a Great Eruption in the 1800s and ejected significant mass into the well-known bipolar Homunculus. But η Car's outer ejecta, a spread of dense, nitrogen-rich knots outside the Homunculus, have led to suspicion that the Great Eruption was not this star's first major mass-loss event. We have measured proper motions for nearly 800 distinct features in the outer ejecta using 21 years of HST WFPC2 and ACS imaging. With motions measured across sixteen baselines, we find that the outer ejecta are expanding ballistically and belong to three age groups: one dating to the mid-1200s, another to the mid-1500s, and a third to the early 1800s, associated with but perhaps predating the peak of the Great Eruption. These three age groups are separated in space and radial velocity. There is no evidence for interaction between the dense ejecta that could be powering η Car's soft X-ray shell, which is instead likely driven by fast, rarefied ejecta from the Great Eruption striking the older dense ejecta. The thirteenth-century event was strikingly asymmetric, ejecting mass almost entirely to one side of the star. The sixteenth-century event displays bipolar symmetry, but along a different axis than the current Homunculus. These observations provide constraints on theoretical models of η Car's behavior, as viable models must explain the repetition, timescale, and asymmetry of these major mass-loss events. For more details, see Kiminki, Reiter, & Smith (2016, MNRAS, 463, 845).
Wind inhibition by X-ray irradiation in high-mass X-ray binaries
Authors: Krtička Jiří , Kubát Jiří , Krtičková Iva 
Published: July 2017

AbstractWinds of hot massive stars are driven radiatively by light absorption in the lines of heavier elements. Therefore, the radiative force depends on the wind ionization. That is the reason why the accretion powered X-ray emission of high-mass X-ray binaries influences the radiative force and may even lead to wind inhibition. We model the effect of X-ray irradiation on the stellar wind in high-mass X-ray binaries. The influence of X-rays is given by the X-ray luminosity, by the optical depth between a given point and the X-ray source, and by the distance to the X-ray source. The influence of X-rays is stronger for higher X-ray luminosities and in closer proximity of the X-ray source. There is a forbidden area in the diagrams of X-ray luminosity vs. the optical depth parameter. The observations agree with theoretical predictions, because all wind-powered high-mass X-ray binary primaries lie outside the forbidden area. The positions of real binaries in the diagram indicate that their X-ray luminosities are self-regulated.
Line-Driven Ablation of Circumstellar Disks
Authors: Kee Nathaniel Dylan , Owocki Stan , Kuiper Rolf , Sundqvist Jon 
Published: July 2017

AbstractMass is a key parameter in understanding the evolution and eventual fate of hot, luminous stars. Mass loss through a wind driven by UV-scattering forces is already known to reduce the mass of such stars by 10−10 − 10−4 M⊙/yr over the course of their lifetimes. However, high-mass stars already drive such strong winds while they are still in their accretion epoch. Therefore, stellar UV-scattering forces will efficiently ablate material off the surface of their circumstellar disks, perhaps even shutting off the final accretion through the last several stellar radii and onto a massive protostar. By using a three-dimensional UV-scattering prescription, we here quantify the role of radiative ablation in controlling the disk’s accretion rate onto forming high-mass stars. Particular emphasis is given to the potential impact of this process on the stellar upper mass limit.