Hotspot Component Research Articles

Potential Social Impacts regarding working conditions of Fuel Cell Electric Vehicles

For a successful energy and mobility transition, multifaceted technologies, e.g., fuel cell electric vehicles (FCEV) are developed. Next to technical advantages, environmental, economic, and social aspects must be considered. Especially the social implications for various stakeholders are often neglected but are no less important. Thus, goal of this study is to identify possible social risks associated with the production of an FCEV in Germany, using the concept of Social Life Cycle Assessment. Social topics investigated are association and bargaining rights, trade unionism, fair salary, gender wage gap and weekly hours of work. Results show that the proton exchange membrane fuel cell is a hotspot component, bearing 31–41% of the risk, which is mainly caused by the membrane. Germany is, next to China and India, the major hotspot country, depending on the social topic. Changes in component prices can have an influence on this, as can be seen at the example of the membrane.

The Description and Application of BRDF Based on Shape Vectors for Typical Landcovers

As the inherent attribute of land cover, anisotropy leads to the heterogeneity of directional reflection; meanwhile, it creates the opportunity for retrieving characteristics of land surface based on multi-angle observations. BRDF (Bidirectional Reflectance Distribution Function) is the theoretical expression of anisotropy and describes the reflectance in terms of incident-view geometry. Prior BRDF knowledge is used to achieve the multi-angle retrieval for earth observation systems with a narrow FOV (Field of View). Shape indicators are a feasible way to capture the characteristics of BRDF or to build an a priori database of BRDF. However, existing shape indicators based on the ratio of reflectance or the weight of scattering effects are too rough to describe the BRDF’s shape. Thus, it is necessary to propose new shape vectors to satisfy the demand. We selected six typical land covers from MODIS-MCD12 on the homogeneous underlayers as the study sites in North America. The daily BRDF is retrieved by MODIS-BRDF parameters and the RossThick-LiSparseR model. When the SZA (Solar Zenith Angle) is set at 45°, seven directions (−70°, −45°, −20°, 0°, 20°, 45°, and 70°) including edge spot, zenith spot, hot spot and approximate dark spot of the BRDF principal plane were selected to construct two vectors by the change rate of reflectance and angle formulation: Partial Anisotropic Vector (PAV) and Angular Effect Vector (AEV). Then, we assessed the effectiveness of PAV and AEV compared with ANIX (Anisotropic Index), ANIF (Anisotropic Factor) and AFX (Anisotropic Flat Index) by two typical BRDF shapes. The representativeness of PAV and AEV for the original BRDF was also assessed by cosine similarity and error transfer function. Lastly, the application of hot spot components in AEV for land cover classification, the monitoring of land cover in mining areas and the adjustment effect by NDVI (Normalized Difference Vegetation Index) were investigated. The results show that (1) the shape vectors have good representativeness compared with original BRDF. The representativeness of PAV assessed by cosine similarity is 0.980, 0.979 and 0.969, and the representativeness of AEV assessed by error transfer function is 0.987, 0.991 and 0.994 in the three MODIS broadbands of Near Infrared (NIR, 0.7–5.0 µm), Short Wave (SW, 0.3–5.0 µm) and Visible (VIS, 0.3–0.7 µm). (2) Some components of shape vectors have high correlation with AFX. The correlation coefficient between hot spot components in AEV and AFX is 0.936, 0.945 and 0.863, respectively, in NIR, SW and VIS bands. (3) The shape vectors show potentiality for land cover classification and the monitoring of land cover in mining areas. The correlation coefficients of hot spot components in AEV for MODIS-pixels with the same types (0.557, 0.561, 0.527) are significantly higher than MODIS-pixels with various types (0.069, 0.055, 0.051) in NIR, SW and VIS bands. The coefficients of variation for hot spot components are significantly higher after land reclamation (0.0071, 0.0099) than before land reclamation (0.0020, 0.0028). (4) The correlation between NDVI and the BRDF shapes is poor in three MODIS broad bands. The correlation coefficients between NDVI and the BRDF shapes in three temporal scales of annual, seasonal and monthly phases are only 0.134, 0.063 and 0.038 (NIR), 0.199, 0.185 and 0.165 (SW), and 0.323, 0.320 and 0.337 (VIS), on average.

NEW PHOTOMETRY AND SPECTROSCOPY OF DW CANCRI

We present new observations of the cataclysmic variable DW Cancri, after the system recovered from a low state. We performed a power spectrum analysis that reveals a clear signal of the 38 min spin period in our photometric data. Our spectroscopic power spectrum search was consistent with studies performed before the low state, showing the orbital and spin modulations. Our Doppler Tomography study exhibits a disc structure and an enhanced asymmetric region, possibly related to a hot spot component. Furthermore, a wavelet transform analysis reveals the 70 min spin-orbit beat period. We interpret these results as an indication of a partial recovery of the system. However, DW Cnc does not yet show all the original photometric modulations reported before the low state. Thus, we propose further observations to elucidate if such original signals require more time to reactivate.

A high-resolution view of the jets in 3C 465

ABSTRACT We present new high-resolution and high-sensitivity studies of the jets in the WAT source 3C 465, using deep transverse-resolved radio observations from e-MERLIN, and with complementary observations from the Very Large Array (VLA). We derive a lower limit βj = (νj/c) ≳ 0.5 for the jet speed, and an upper limit $\theta _{\rm j}\, \lesssim$ 61° for the jet angle to the line of sight. The jet spectral index (α, defined in the sense S ∝ να) is fairly constant (<αjet > = − 0.7), and spectral flattening within 4.4 kpc of the core coincides with bright knots and is consistent with the site of X-ray particle acceleration at the base of the radio jet found in previous studies. There is little difference between the spectra of the two hotspot components, plausibly indicating that electron populations of the same properties are injected there. The north-west (NW) and south-east (SE) plumes are approximately homologous structures, with variations in mass injection and propagation in external pressure and density gradients in the two regions plausibly accounting for the slightly steeper spectrum in the NW plume, <αNWp> = −1.43 compared with the SE plume, <αSEp> = −1.38. Our synchrotron lifetime model supports plausible reacceleration of particles within the plume materials. Overall, our results show that the first-order Fermi process at mildly relativistic and non-relativistic shocks is the most likely acceleration mechanism at play in 3C 465 and distinguish differences between the acceleration at $\beta _{\rm j}\, \gt $ 0.5 and $\beta _{\rm j}\, \lt $ 0.5. The former case can accelerate electrons to higher Lorentz factors.

Jansky VLA observations of synchrotron emitting optical hotspots of 3C 227 and 3C 445 radio galaxies

ABSTRACT We report results on deep Jansky Very Large Array (VLA) A-configuration observations at 22 GHz of the hotspots of the radio galaxies 3C 227 and 3C 445. Synchrotron emission in the optical on scales up to a few kpc was reported for the four hotspots. Our VLA observations point out the presence of unresolved regions with upper limit to their linear size of about 100 pc. This is the first time that such compact components in hotspots have been detected in a mini-sample, indicating that they are not a peculiar characteristic of a few individual hotspots. The polarization may reach values up to 70 per cent in compact (about 0.1 kpc scale) regions within the hotspot, indicating a highly ordered magnetic field with size up to a hundred parsecs. On larger scales, the average polarization of the hotspot component is about 30–45 per cent, suggesting the presence of a significant random field component, rather than an ordered magnetic field. This is further supported by the displacement between the peaks in polarized intensity and in total intensity images that is observed in all the four hotspots. The electric vector position angle is not constant, but changes arbitrarily in the central part of the hotspot regions, whereas it is usually perpendicular to the total intensity contours of the outermost edge of the hotspot structure, likely marking the large-scale shock front. The misalignment between X-ray and radio-to-optical emission suggests that the former is tracing the current particle acceleration, whereas the latter marks older shock fronts.

Oregon’s All Roads Transportation Safety Program: Data-Driven Program to Improve Safety on All Public Roads

Historically, the Oregon Department of Transportation (DOT) has spent the Highway Safety Improvement Program (HSIP) funding only on state highways. However, half of the fatalities and serious injuries occur on nonstate roadways. To address this concern and to comply with the federal requirement that the HSIP funding be spent on all public roads, the Oregon DOT developed a jurisdictionally blind safety program, known as the All Roads Transportation Safety (ARTS) Program, to address safety problems on all public roads in Oregon. The objective of the ARTS Program is the same as that of the HSIP: to reduce fatalities and serious injuries on all public roads using a data-driven approach. The ARTS Program has two components: hot spot and systemic. For the first round of the ARTS Program, safety projects were selected by using a combination of a selection approach and an application-based approach. For the hot spot component, potential safety projects were identified by using crash history, and the projects were prioritized on the basis of benefit–cost ratios. The systemic component—with three emphasis areas: roadway departure, intersection, and pedestrian and bicycle—was an application-based process in which the Oregon DOT and local agencies competed for available safety funding. Systemic projects were prioritized on the basis either of benefit–cost ratios (roadway departure and intersection projects) or cost-effectiveness index (pedestrian and bicycle projects). Through collaboration with various stakeholders, the Oregon DOT was able to select safety projects on all public roads with a data-driven approach. It is expected that these projects will significantly improve safety on all Oregon roads by reducing fatal and serious injury crashes.

Spatial distribution of helium isotopes in volcanic gases and thermal waters along the Vanuatu (New Hebrides) volcanic arc

We report the first helium isotope survey of volcanic gases, hot springs and some olivine phenocrysts along the Vanuatu island arc, from Tanna in the south to Vanua Lava in the north. Low CO2 content and low 3He/4He ratios in thermal fluids of Epi (4.0±0.1Ra), Efate (4.5±0.1Ra) and Pentecost (5.3±0.5Ra) islands coherently indicate reduced mantle gas leakage and crustal contamination by radiogenic helium on these extinct volcanic systems of the former (Pliocene) arc. Instead, presently active Vanuatu volcanoes display 3He/4He and C/3He ratios typical of subduction-related volcanic arcs: 3He/4He ratios range from 6.4±0.5Ra in southernmost Tanna and 7.23±0.09Ra in northernmost Vanua Lava to typical MORB values in the central islands of Gaua (7.68±0.06Ra), Ambrym (7.6±0.8Ra) and Ambae (7±2Ra in groundwaters, 7.9±1.4Ra in olivine phenocrysts, and 8.0±0.1Ra in summit fumaroles of Aoba volcano). On Ambrym, however, we discover that hydrothermal manifestations separated by only 10–15km on both sides of a major E–W transverse fault zone crossing the island are fed by two distinct helium sources, with different 3He/4He signatures: while fluids in southwest Ambrym (Baiap and Sesivi areas) have typical arc ratios (7.6±0.8Ra), fluids on the northwest coast (Buama Bay area) display both higher 3He/4He ratios (9.8±0.2Ra in waters to 10.21±0.08Ra in bubbling gases) and lower C/3He ratios that evidence a hotspot influence. We thus infer that the influx of Indian MORB mantle beneath the central Vanuatu arc, from which Ambrym magmas originate, also involves a 3He-rich hotspot component, possibly linked to a westward influx of Samoan hotspot material or another yet unknown local source. This duality in magmatic He source at Ambrym fits with the bimodal composition and geochemistry of the erupted basalts, implying two distinct magma sources and feeding systems. More broadly, the wide He isotopic variations detected along the Vanuatu arc further verify the complex tectonic and magmatic framework of this intra-oceanic island arc.

Mantle hotspot neon in basalts from the Northwest Lau Back‐arc Basin

The neon isotope compositions of basalts from the Northwest Lau Back‐arc Basin reflect three‐component mixing between an ocean island basalt (OIB) mantle hotspot component, mid‐ocean ridge basalt (MORB) mantle, and atmosphere. Our study confirms that a mantle hotspot signature is present in the neon isotopes of both the Rochambeau Rifts and the Northwest Lau Spreading Center (NWLSC), just as it is in the helium isotopes. Furthermore, the Ne isotope signature in the Rochambeau Rifts lava having the highest3He/4He ratio (28 Ra) most closely resembles that observed previously in the highest 3He/4He lavas from Samoa. The coupled He–Ne isotope systematics are further evidence for incursion into this region of material derived from the Samoan mantle plume.

Complex particle acceleration processes in the hotspots of 3C 105 and 3C 445★

We investigate the nature of the broad-band emission associated with the low-power radio hotspots 3C105 South and 3C445 South. Both hotspot regions are resolved in multiple radio/optical components. High-sensitivity radio VLA, NIR/optical VLT and HST, and X-ray Chandra data have been used to construct the multi-band spectra of individual hotspot components. The radio-to-optical spectra of both hotspot regions are well fitted by a synchrotron model with steep spectral indices ~0.8 and break frequencies 10^12-10^14 Hz. 3C105 South is resolved in two optical components: a primary one, aligned with the jet direction and possibly marking the first jet impact with the surrounding medium, and a secondary, further out from the jet and extended in a direction perpendicular to it. This secondary region is interpreted as a splatter-spot formed by the deflection of relativistic plasma from the primary hotspot. Radio and optical images of 3C445 South show a spectacular 10-kpc arc-shape structure characterized by two main components, and perpendicular to the jet direction. HST images in I and B bands further resolve the brightest components into thin elongated features. In both 3C105 South and 3C445 South the main hotspot components are enshrouded by diffuse optical emission on scale of several kpcs, indicating that very high energy particles, possibly injected at strong shocks, are continuously re-accelerated in situ by additional acceleration mechanisms. We suggest that stochastic processes, linked to turbulence and instabilities, could provide the required additional re-acceleration.

A DOUBLED DOUBLE HOT SPOT IN J0816+5003 AND THE LOGARITHMIC SLOPE OF THE LENSING POTENTIAL

We present an analysis of observations of the doubly-lensed double hotspot in the giant radio galaxy J0816+5003 from MERLIN, MDM, WIYN, WHT, UKIRT and the VLA. The images of the two hotspot components span a factor of two in radius on one side of the lensing galaxy at impact parameters of less than 500pc. Hence we measure the slope of the lensing potential over a large range in radius, made possible by significant improvement in the accuracy of registration of the radio and optical frame and higher resolution imaging data than previously available. We also infer the lens and source redshifts to be 0.332 and > 1 respectively. Purely on the basis of lens modelling, and independently of stellar velocity dispersion measurements, we find the potential to be very close to isothermal.

SDSS 1507+52: A Halo Cataclysmic Variable?11Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan.

ABSTRACTWe report a photometric and spectroscopic study of the peculiar cataclysmic variable SDSS 1507+52. The star shows very deep eclipses on the 67-minute orbital period, and those eclipses are easily separable into white-dwarf and hot-spot components. This leads to tight constraints on binary parameters, with M1 = 0.83(8) M⊙, M2 = 0.057(8) M⊙, R1 = 0.0097(9) R⊙, R2 = 0.097(4) R⊙, q = 0.069(2), and i = 83.18(13)°. Such numbers suggest possible membership among the WZ Sge stars, a common type of dwarf nova. The spectroscopic behavior (strong and broad H emission, double-peaked and showing a classic rotational disturbance during eclipse) is also typical. But the star’s orbital period is shockingly below the “period minimum” of ∼77 minutes that is characteristic of hydrogen-rich CVs; producing such a strange binary will require some tinkering with the theory of cataclysmic-variable evolution. The proper motion is also remarkably high for a star of its distance, which we estimate from photometry and trigonometric parallax as 230 ± 40 pc. This suggests a transverse velocity of 164 ± 30 km s-1 —uncomfortably high if the star belongs to a Galactic-disk population. These difficulties with understanding its evolution and space velocity can be solved if the star belongs to a Galactic-halo population.

Search for a deep-mantle component in mafic lavas using a Nb–Y–Zr plot

Concentrations of trace elements with bulk distribution coefficients < 1 have been utilized to discriminate between mafic magmas erupted in different tectonic settings. Herein, the Nb–Y–Zr contents of mafic lavas will be utilized to pinpoint derivation from a deep-mantle source. Magmas derived from the Icelandic plume exhibit ΔNb > 0, where ΔNb = log (Nb/Y) + 1.74 – 1.92 log (Zr/Y) (Fitton et al. 1997), whereas melts derived from depleted sections of the mantle and the crust show ΔNb < 0. Regardless of the nature of the melting event, it was suggested the ΔNb value of magmas were essentially identical to that of the source material. Theoretical modeling of a garnet lherzolite source suggests very small partial melts may show elevated ΔNb values, yielding a spurious plumelike signature. For mafic rocks from different areas, with hypothesized hot spot derivation, ΔNb is calculated to search for a deep-mantle signature (ΔNb > 0). The signature of the Réunion hot spot, from ~65–0 Ma, is seen in the Deccan Traps, India, lavas from the Mascarene Plateau, and Réunion Island. The signature of the Kerguélen plume is detected in rocks from Kerguélen Island and the Ninetyeast and Broken Ridges, Indian Ocean, a few lavas from the Rajmahal province, India, but none in the Bunbury Basalt, Australia. Some rocks from continental flood basalt provinces show a hot spot component, in agreement with conclusions based on 3He/4He studies, others show ΔNb < 0, due to considerable subcontinental contamination. For lavas from Heard Island and Grand Comore, Indian Ocean, the technique pinpoints those showing a plume component. In an area of plate convergence in the Pacific Ocean, lavas with very low (<1 ppm) Nb contents, serve as a critical test for this method. Only rocks close to the Samoan hot spot show ΔNb > 0, whereas the others show the Nb depletion typical of arc-related material. In conjunction with trace-element and isotopic discriminants, this appears to be a useful tool in identifying a deep-mantle component in mafic lavas from a variety of plate tectonic settings.

Analysis of the interactions of human ribonuclease inhibitor with angiogenin and ribonuclease A by mutagenesis: importance of inhibitor residues inside versus outside the C-terminal “hot spot”

Ribonuclease inhibitor (RI) binds diverse mammalian RNases with extraordinary avidity. Here, we have investigated the structural basis for this tight binding and broad specificity by mutational analysis of the complexes of RI with angiogenin (Ang) and RNase A (KD=0.5 fM and 43 fM, respectively). Both crystal structures are known; the interfaces are large, and the ligands dock similarly, although few of the specific interactions formed are analogous. Our previous mutagenesis studies focused primarily on one contact region, containing RI 434–438 and the enzymatic active site. Many single-residue replacements produced extensive losses of binding energy (2.3–5.9 kcal/mol), suggesting that this region constitutes a “hot spot” in both cases. We have now explored the roles of most of the remaining RI residues that interact with Ang and/or RNase A. One major cluster in each complex lies in a Trp-rich area of RI, containing Trp261, Trp263, Trp318, and Trp375. Although the energy losses from individual replacements in this portion of the Ang complex were small-to-moderate (0–1.5 kcal/mol), the changes from multiple substitutions were much greater than additive, and the binding energy provided by this region is estimated to be ∼6 kcal/mol (30 % of total). Effects of replacing combinations of hot spot components had also been found to be superadditive, and this negative cooperativity is now shown to extend to the neighboring contact residue RI Ser460. The overall contribution of the hot spot, taking superadditivity into account, is then ∼14–15 kcal/mol. The hot spot and Trp-rich regions, although spatially well separated, are themselves functionally linked. No other parts of the RI-Ang interface appear to be energetically important. Binding of RNase A is more sensitive to substitutions throughout the interface, with free energy losses⩾1 kcal/mol produced by nearly all replacements examined, so that the sum of losses greatly exceeds the binding energy of the complex. This discrepancy can be explained, in part, by positive cooperativity, as evident from the subadditive effects observed when combinations of residues in either the hot spot or Trp-rich region are replaced. These findings suggest that the binding energy may be more widely distributed in the RNase A complex than in the Ang complex.

Quiescent accretion disks in black hole X-ray novae

We present detailed time-resolved spectroscopy of the Balmer emission lines from two black hole binary systems in quiescence, A0620-00 and Nova Muscae 1991. We find extraordinary similarities between the two systems. There are 30-40 km/s velocity variations of the emission lines over the orbital period, the phases of which are not aligned with the expected phase of the motion of the compact primary. Detailed modeling of both systems is complicated by variable hot spot components, regions of optical thickness, and intermittent excess emission in the blue line wings of the H-alpha lines. Both sources also display low velocities at the outer edge of the accretion disk, implying a large primary Roche lobe and extreme mass ratios. These complications suggest that although simple optically thin, Keplerian alpha-disk models provide a useful parameterization of emission lines from these systems, the straightforward physical models they imply should be treated with great caution.