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The aggregate behavior of hot spots in shocked plastic-bonded explosives (PBX) was studied by nanosecond optical pyrometry. The averaged thermal emission spectra from at least 25 tiny (50 μg) explosive charges of a pentaerythritol tetranitrate PBX, at several impact velocities from 1.5 to 4.5 km/s, was used to determine average temperatures and emissivities. Individual spectra were analyzed to determine the distribution of hot spot temperatures in individual charges with unique microstructures. Understanding shocks in tiny charges with different microstructures is needed to understand shocks in large PBX charges which sample many microstructures as they propagate. The initial hot spot density was several percent, and the average initial hot spot temperature of 4000 K was, surprisingly, independent of impact velocity. With underdriven shocks, the initial hot spot temperatures clustered around 4000 K, but with overdriven shocks, there were both hotter and colder hot spots. The initial hot spot density increased quadratically with impact velocity. The generation of hot spots was described by a model with a threshold energy to trigger hot spot formation and a distribution of energetic barriers to hot spot formation. [ABSTRACT FROM AUTHOR]

The Hawaiian-Emperor seamount chain that includes the Hawaiian volcanoes was created by the Hawaiian mantle plume. Although the mantle plume hypothesis predicts an oceanic plateau produced by massive decompression melting during the initiation stage of the Hawaiian hot spot, the fate of this plateau is unclear. We discovered a megameter-scale portion of thickened oceanic crust in the uppermost lower mantle west of the Sea of Okhotsk by stacking seismic waveforms of SS precursors. We propose that this thick crust represents a major part of the oceanic plateau that was created by the Hawaiian plume head ~100 million years ago and subducted 20 million to 30 million years ago. Our discovery provides temporal and spatial clues of the early history of the Hawaiian plume for future plate reconstructions. [ABSTRACT FROM AUTHOR]

A detailed analysis has been carried out to study efficient heating due to microwaves for one-dimensional samples placed on ceramic supports (Al2O3, SiC). The greater effects on microwave heating of samples have been illustrated via average power within a sample versus sample thickness diagram for various cases. The maxima in power, also termed as “resonances,” is observed for specific sample thicknesses and the two consecutive maxima in average power are termed as R1 and R2 modes. The greater heating effects leading to hot spots would occur in water samples during both-sides incidence when the sample is kept on Al2O3 support. SiC support may be recommended for water samples due to uniform heating throughout the sample. In contrast, SiC support could cause local hot spots or thermal runaway for oil samples. The localized hot spots are more pronounced for the samples exposed to microwaves on both faces. The choice of support may not be trivial due to the complex dielectric response of sample-support assembly. Current analysis has been illustrated for low- and high-dielectric materials (water and oil) and a representative case study has also been shown for beef samples. Based on such observations, a generalized heating strategy for materials due to uniform plane waves has been derived. [ABSTRACT FROM AUTHOR]

The central and western Sahara is the largest source of mineral aerosols during boreal summer, but observed ground‐based data are extremely scarce and typically distant from key source regions. Knowledge of dust emission mechanisms has therefore been mostly limited to short‐term observations from a point or model approximations. To address this deficiency, dust plumes from the central and western Sahara are classified according to emission mechanism for June, July, and August of 2004–2017 using an automated inference method, which accurately tracks the timing, convective association, and geometry of plumes observed with the Spinning Enhanced Visible and Infrared Imager aboard Meteosat Second Generation satellites. From these characteristics, plumes are classified as either low‐level jet or cold pool outflow events. The extensive data set is used to generate the largest available climatology of dust emission sources and Saharan emission mechanisms. Automated inference compares well with ground‐based measurements from the Fennec Campaign (76% accuracy) as well as with an entirely manual approach (88% accuracy). Cold pool activity accounts for 82% of total observed dust and 88% at the point of emission. Dust from cold pools evolves seasonally from hot spots around the Mali‐Niger‐Algeria border triple point toward the central Sahara to the northwest, while dust from low‐level jets is organized along the axis of the northeasterly Harmattan, and dominates emission within the Tidihelt Depression of central Algeria. The widespread importance of cold pool outflows in this research supports the findings of the Fennec Campaign, but low‐level jets remain highly significant in certain isolated hot spots. Key Points: A novel method is developed to identify emission mechanisms from automatically tracked dust plumes in the central and western SaharaDust plumes across 14 summers are tracked individually and classified probabilistically as low‐level jet or cold pool outflow eventsEighty‐two percent of dust pixels are associated with cold pool outflow events, but low‐level jets dominate in the highly active Tidihelt Depression [ABSTRACT FROM AUTHOR]

A Regional Extreme Climatic Change Index (RECCI), simultaneously considering the changes in intensity, frequency and interannual variability of three major extreme climatic variables (i.e., precipitation, temperature and wind speed), is constructed to represent regional changes of climate extremes in response to global warming. First, the daily outputs from 13 models in the Coupled Model Intercomparison Project phase 5 project in both historical and future simulations under the Representative Concentration Pathway 8.5 scenario are used to compute the extreme climatic indices. Second, the RECCI is computed on both annual and seasonal time scales during three periods (i.e., 2016–2035, 2046–2065 and 2080–2099) over 26 subregions. Finally, the spatiotemporal change of the RECCI is investigated, and then, the 26 subregions are classified into four categories for each period. The first category with the largest RECCI value is very sensitive to global warming, which is called hot spots of climate extremes. The results show that most hot spots are not time invariant on annual and seasonal time scales with some exceptions. On the annual time scale, the Amazon Basin is the only persistent hot spot in all three periods. For the seasonal time scale in March‐April‐May, the climate extremes in the Amazon Basin always display the strongest responsiveness to global warming, and the Eastern Africa is the only persistent hot spot in June‐July‐August in three periods. Similar results are also found for the other two seasons and periods. In addition, the change in extreme temperature is crucial over the East Asia with change in frequency prominent. Key Points: The majority of the regions in different categories of climate extremes are not time invariant on annual and seasonal time scalesThe Amazon Basin is the only persistent hot spot of climate extremes in 2016–2035, 2046–2065 and 2080–2099The Regional Extreme Climatic Change Index is a robust metric that is not sensitive to the actual models chosen [ABSTRACT FROM AUTHOR]

In this article, a dynamic ignition criterion for magnetized cylindrical implosions is derived. The analysis of the hot spot dynamics after stagnation performed by Christopherson et al. [Phys. Plasmas 25, 012703 (2018)] for spherical implosions is extended to cylindrical geometry with the addition of an external magnetic field. The hot spot dynamics have been consistently solved with a kinetic model for the alpha particle motion. The magnetic field confines the alpha particles and enhances their energy deposition inside the fuel. The ignition criterion is based on the identification of ignited solutions, where pressure exhibits a singularity in finite time and neutron yield diverges. It is formulated in terms of a normalized Lawson parameter and the magnetization of the alpha particles at stagnation. The beneficial effect of magnetizing the fuel to increase the neutron yield is asserted by the analysis. [ABSTRACT FROM AUTHOR]

Thermal anomaly spots (both hot and cold) have been found in the global 37-GHz brightness temperature (TB) map of the moon based on the Chang’E (CE) microwave radiometer measurements. To explain their origin, a rock model is proposed to simulate the TB variation against latitude along the profile of a fresh crater in a single track way, which is selected to highlight the topographic effect and avoid any modification to the data. A mixed upper layer made up of rock and soil (regolith and dust) was employed into our previous multilayer model. The thermal properties (thermal conductivity and heat capacity) of the mixture layer are presumed to be linear with the fraction of rocks. Given that high-frequency (37 GHz) measurements are chosen, only the meter size and larger rocks of the upper mixed layer are considered to avoid scattering effects. Several fresh craters poor/rich in ilmenite are selected as testing sites. Despite uncertainties in parameters such as rock abundance (RA), and iron and titanium abundances, three conclusions can be reached from these cases: 1) RA has a significant effect on both the TB value and TB variation trend against latitude; its contribution over some craters may be as high as 15 K; 2) the simulations based on our rock model fit the CE observations better than those when rocks are not included; and 3) the rock and ilmenite contributions could be the main cause for the cold and hot spots found in the CE microwave map. [ABSTRACT FROM AUTHOR]

Hot spots generated from the ultra-small nanogaps will tremendously contribute to the strong electromagnetic field. Therefore, the establishment and design of nanogaps are extremely significant. Here, a hierarchical structure, AgNPs/bilayer graphene/Au nanonet, was proposed to form the dense three-dimensional (3D) hot spots and demonstrated in experiment and theory. Numerous nanometer gaps in the complex Au nanonet structure (∼8.67 nm) and in AgNPs/Au nanonet isolated by bilayer graphene (0.64 nm) were achieved, which is much beneficial for the obtainment of the hot spots. Based on this surface enhanced Raman scattering (SERS) substrate, an excellent SERS activity (EF ∼ 9.1 × 10 9 ), high sensitivity (10 −13 and 10 −12  M respective for Rhodamine 6G (R6G) and crystal violet (CV)), and SERS signals homogeneity, outstanding reproducibility (maximum intensity deviation from substrate to substrate ∼10.43%) were obtained, which can be attributed to the abundant lateral and vertical hot spots introduced by the hierarchical structure. Moreover, the proposed SERS substrate was used to sensitively detect the harmful malachite green (MG), which exhibits a great prospect as a potential SERS sensor in food safety field and biochemical molecules. [ABSTRACT FROM AUTHOR]

Microwave heating technology is widely used in food catering and domestic households. Non- uniformity of microwave temperature distribution causes the formation of hot and cold spots in heated product has led to the survival of foodborne pathogens which may later cause food borne diseases. It is the aim of this study to determine the effect of different microwave heating on the microbiological quality of microwavable frozen chicken curries. Nine commercialised frozen chicken curries were thawed overnight in the chiller (< 4°C) and exposed to different microwave power levels and times (270 W at 60 s; 950 W at 150 s and 300 s). 25 g of chicken curry were homogenised, serial diluted and enumerated aseptically. Total Aerobic Count (TAC), Total Coliform Count (TCC), Escherichia coli count and Salmonella count were carried out and no microorganisms were detected. Enterobacteriaceae were found in the food samples after enrichment process. Polymerase Chain Reaction (PCR) amplification and 16S ribosomal ribonucleic acid (rRNA) sequencing were carried out. Results of 16S rRNA sequence analysis indicated that two gram-negative isolates after enrichment were identified as Klebsiella pneumoniae. [ABSTRACT FROM AUTHOR]

VZ Psc is a W-type contact binary system with a short period of 0.26125897 days. B, V, R c and I c light curves of the eclipsing binary system were obtained by using the 1.0 m reflecting telescope at Weihai Observatory of Shandong University. By collecting 136 times of minimum light, we studied the orbital period change of VZ Psc. A sinusoidal variation was discovered in the O − C diagram, and the amplitude of 0. d 0023 and the period of 17.7 year were obtained. This can be caused by Applegate mechanism or light-time effect. Both the mechanisms are suited according to our investigation, but we prefer the latter that the light-time effect due to the presence of a third body results in the cyclic variation. By using the W-D program, we analyzed the four color light curves. Because of the asymmetric light curves and the possible third body, we used the spot mode of W-D program with and without L 3 . We found that a hot spot on the primary component with the third light leads to the best result. A very high filling factor of 94.4% ± 2.8% and orbit inclination of 53.2° were obtained. [ABSTRACT FROM AUTHOR]

We consider the possibility that tidal disruption events (TDEs) caused by supermassive black holes (SMBHs) in nearby galaxies can account for the ultrahigh-energy cosmic ray (UHECR) hotspot reported recently by the Telescope Array (TA) and the warm spot by Pierre Auger Observatory. We describe the expected cosmic ray signal from a TDE and derive the constraints set by the time-scale for dispersion due to Galactic and intergalactic magnetic fields and the accretion time of the SMBH. We find that TDEs in M82 can explain the hotspot detected by the TA regardless of whether the UHECRs are composed of protons or heavier nuclei. We then check for consistency of the hot and warm spots from M82 and Cen A with the full-sky isotropic signal from all SMBHs within the Greisen-Zatsepin-Kuzmin (GZK) radius. This analysis applies to any scenario in which the hot/warm spots are real and due to M82 and Cen A, regardless of whether TDEs are the source of UHECRs. We find that the isotropic flux implied by the luminosity density inferred from M82 and Cen A is bigger than that observed by roughly an order of magnitude, but we provide several possible explanations, including the possibility of a local overdensity and the possibility of intermediate-mass nuclei in UHECRs, to resolve the tension. [ABSTRACT FROM AUTHOR]

The results of X-pinch experiments performed using a small-sized pulse generator are analyzed. The generator, capable of producing a 200-kA, 180-ns current, was loaded with an X-pinch made of four 35-lm-diameter aluminum wires. The analysis consists of a one-dimensional radiation magnetohydrodynamic simulation of the formation of a hot spot in an X-pinch, taking into account the outflow of material from the neck region. The radiation loss and the ion species composition of the pinch plasma are calculated based on a stationary collisional-radiative model, including balance equations for the populations of individual levels. With this model, good agreement between simulation predictions and experimental data has been achieved: the experimental and the calculated radiation power and pulse duration differ by no more than twofold. It has been shown that the x-ray pulse is formed in the radiative collapse region, near its boundary. [ABSTRACT FROM AUTHOR]

The ITER-like tungsten divertor with toroidally symmetric 1 mm × 1 mm chamfers on monoblock tiles has been installed in EAST in 2014. Hot spots were experimentally observed mostly along the toridial facing gaps between two columns of W/Cu monoblock units, which are often aggravated by installation misalignment. These hot spots can significantly degrade the power handling capability of W divertor and need to be alleviated. A numerical optimization model for tile chamfering design is built based on the finite element method (FEM), in which the numerical experiments are designed by the uniform table. The calculation results in ANSYS for these experiments are then processed employing the code Design and Analysis of Computer Experiments (DACE) in which the Kriging method is adopted to reconstruct a response surface. The optimum geometry can be derived from the minimum point on the surface. The results show that, under 200 MW/m 2 parallel heat flux with an inclination angle of 3° with respect to tile surface, the maximum temperature on W tile with a 0.5 mm misalignment can be decreased to 2084 °C by adopting an optimized single-sided chamfer, 1.8 times lower than 1 mm × 1 mm symmetrically chamfered tile. The optimum chamfering geometry has a strong dependence on the inclination angle of plasma flux to tile surface. As a result, the monoblock tiles in a flat cassette module need to be chamfered differently to adapt to the varied inclination angles. [ABSTRACT FROM AUTHOR]

The emergence of 2D SERS substrates with large areas of hot spots has enabled data to be gathered at large scale. This work presents a statistical tool for analysing large amounts of SERS data by utilizing a peak-fitting model in a specific spectral range. By analysing the distributions of Raman intensities and peak positions it is possible to directly inspect the interplay between DNA and 6-mercapto-1-hexanol on gold covered nanopillars. It is demonstrated that optimised functionalization parameters can be extracted from the Raman spectra directly. Using the peak-fitting approach it is possible to avoid miss-interpretation of intensity histograms, where contamination might contribute with an enhanced background and not a peak. [ABSTRACT FROM AUTHOR]

According to theoretical predictions, young extragalactic radio sources may release a significant fraction of their total radiative power in the high-energy domain. X-ray emission is expected from the central active galactic nucleus (AGN), and from the extended radio components, jet, hot spots, and lobes. The X-rays should also trace the interactions of the radio source with its environment, and reveal to us how the young source clears its way out of the host galaxy and finally reaches the giant stage. Observational campaigns with Chandra and XMM- Newton telescopes have confirmed that young radio sources are indeed relatively X-ray luminous. Recently, efforts have been undertaken to obtain a complete X-ray view of the whole population of young sources, focusing on the youngest and faintest objects. At the same time, the study of the X-ray properties of the samples of quasars and galaxies provides us with clues on the nature of the observed high-energy emission. In specific cases, X-ray and multi-wavelength data allow for a direct test of the different models. A detection in the y-ray band would represent a robust proof of a non-thermal, high-energy component and the launch of the Fermi telescope has opened the hunt to young radio sources in the y-ray window. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We present the results of multifrequency VLBA observations of J1944+5448 and J0111+3906. These sources are compact symmetric objects, completely embedded in the narrow line region of the host galaxy. Multi-epoch observations allowed us to derive the hot-spot separation speed that was used to estimate the kinematic age of both sources. Their asymmetric shape is likely due to an inhomogeneous ambient medium with which these sources interact. Finally we present the results on the spectral analysis of J0111+3906 whose spectrum is fitted with either a synchrotron self-absorption mechanism or a free free absorption model. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Disordered noble-metal nanoparticle films exhibit highly localized and stable nonlinear light emission from subdiffraction regions upon illumination by near-infrared femtosecond pulses. Such hot spot emission spans a continuum in the visible and near-infrared spectral range. Strong plasmonic enhancement of light-matter interaction and the resulting complexity of experimental observations have prevented the development of a universal understanding of the origin of light emission. Here, we study the dependence of emission spectra on excitation irradiance and provide the most direct evidence yet that the continuum emission observed from both silver and gold nanoparticle aggregate surfaces is caused by recombination of hot electrons within the conduction band. The electron gas in the emitting particles, which is effectively decoupled from the lattice temperature for the duration of emission, reaches temperatures of several thousand Kelvin and acts as a subdiffraction incandescent light source on subpicosecond time scales. [ABSTRACT FROM AUTHOR]

Active debris removal is one of current hot spots in space research, necessary for space exploitation durability. Different techniques have been proposed for this challenging task, among them the use of throw-nets and tow-tethers seems promising: that opens new challenges for Guidance Navigation and Control (GNC) design, especially whenever flexible connections are involved. Via numerical simulations using a multi-body dynamics simulation tool developed at Politecnico di Milano – Department of Aerospace Science and Technology, this paper shows that tethered-net systems are a promising technology to capture and remove space debris and discusses the main difficulties that are likely to take place during capture and disposal phases, particularly from a GNC point of view. [ABSTRACT FROM AUTHOR]

The results of modeling the structure and spectra of hot accretion spots on the surface of young stars with allowance made for the departures from LTE for hydrogen and helium are presented. The existence of ram pressure of the infalling gas at the outer boundary of the hot spot has been found to lead to Stark broadening of the hydrogen line profiles to ∼1000 km s at the accretion parameters considered. It is shown that allowance for the departures from LTE for carbon and oxygen atoms and ions does not lead to noticeable changes in the structure of the hot spot. [ABSTRACT FROM AUTHOR]

Context. L1157-mm powers a molecular outflow that is well-known for its shock-induced chemical activity in several hot-spots. Aims. We have studied the molecular emission toward L1157-mm searching for a jet component responsible for these spots. Methods. We used the IRAM 30 m telescope to observe the vicinity of L1157-mm in several lines of SiO. Results. The SiO(5-4) and SiO(6-5) spectra toward L1157-mm present blue and red detached components about 45 km s-1 away from the ambient cloud. These extremely high-velocity (EHV) components are similar to those found in the L1448 and IRAS 04166+2706 outflows and probably arise from a molecular jet driven by L1157-mm. Observations of off-center positions indicate that the jet is unresolved in SiO(5-4) (<11"). Conclusions. The EHV jet seen in SiO probably excites L1157-B1 and the other chemically active spots of the L1157 outflow. [ABSTRACT FROM AUTHOR]

In this work, two-dimensional hot spots are modelled by combining a linear temperature gradient with a constant temperature plateau. This approach retains the simplicity of a linear temperature gradient, but captures the effects of a local temperature maximum of finite size. Symmetric and asymmetric plateau regions are modelled using both rectangular and elliptical geometries. A one-step Arrhenius reaction for H2–air is used to model the reactive mixture. Plateaus with different ratios of excitation to acoustic timescales, spanning two orders of magnitude, are simulated. Even with clear differences in behaviour between one and two dimensions, thea prioriprescribed hot spot timescale ratio is shown to characterise the 2-D gasdynamic response. The relationship between one and two dimensions is explored using asymmetric plateau regions. It is shown that 1-D behaviour is recovered over a finite time. Furthermore, the duration of this 1-D behaviour is directly related to the asymmetry of the plateau. [ABSTRACT FROM PUBLISHER]

We present data exhibiting the spontaneous emergence of hot spots in forward biased thin film photovoltaics based on a-Si:H technology. These spots evolve over time, shrinking in their diameter and increasing in temperature up to approximately 300 °C above that of the surrounding area. Our numerical approach explores a system of many identical diodes in parallel connected through the resistive electrode and through thermal connectors, a model which couples electric and thermal processes. The modeling results show that hot spots emerge from a rather large area of nonuniform temperature, then collapse to local entities. Finally, we present a simplified analytical treatment establishing relations between the hot spot parameters. The technological importance of our findings is that they open a venue to improving the large area device performance and reliability by properly scaling the device thickness, substrate material, and thermal insulation. [ABSTRACT FROM AUTHOR]

Abstract: New complete BV light curves of a poorly investigated contact binary HH Ursae Majoris (HH UMa) are presented. The light curves are analyzed by using the 2003 version of the Wilson–Devinney (W–D) code. Combining with the radial velocity published by the previous investigators, we obtain the photometric solution of the system. The solution indicates that HH UMa is a W-type W UMa system with a mass ratio of and a contact degree of 31.9%. The system has a very low inclination of and a temperature difference of 247K between two components. The asymmetry of the light curves can be explained by adding a hot spot located near the neck region of the more massive component. A period investigation based on all available data shows that the period increases at a rate of daysyr−1, which can be explained by mass transfer from the less massive component to the more massive one. We also give the absolute parameters of the system. [Copyright &y& Elsevier]

Availability of long-term and high-quality instrumental climate records is still insufficient and the rich heritage of meteorological surface observations is largely underexploited in many parts of the world. This is particularly striking over the Greater Mediterranean region ( GMR), where meteorological observations have been taken since the 18th century at some locations. The lack of high quality and long series here is despite this region being regarded as a climate change hot spot. This article mainly assesses relevant sources containing Mediterranean historical climate data and metadata either from online repositories worldwide or physical archives, with the emphasis here on the rich holdings kept at French archives. A particular case study is the data rescue ( DARE) program undertaken by the Algerian National Meteorological Service, as well as some of the past and ongoing projects and initiatives aimed at enhancing climate data availability and accessibility over the GMR. Our findings point to the high potential for undertaking DARE activities over the GMR and the need for bringing longer and higher quality climate time series to support a diverse number of scientific and technical assessments and policies. [ABSTRACT FROM AUTHOR]

We investigate giant radio galaxy candidates that were selected based on the components cataloged as separate sources in the NVSS survey. The radio and optical identification is done for fifty radio galaxies using the CATS, NED, and SkyView databases. [ABSTRACT FROM AUTHOR]

Abstract: As the demand for thin displays with more features accelerates, the need for backlight systems to become thinner and capable of multiple features increases. Direct lit concepts supporting 2-D dimming provide higher contrast ratios. However masking led hot spots with thinner backlight thicknesses is yet a significant design challenge. Efficient light coupling and recycling mechanisms in combination with relatively high optical efficiencies are key parameters in overall system design. We demonstrate an optimal masking design of the led hot spot for a thin light guide plate in the direct lit architecture. The overall concept system is simulated and prototyped. The resultant performance is discussed. [Copyright &y& Elsevier]

Context. Some classical T Tauri stars, with intense line and continuous excess emission, show extremely complex spectral variations. Aims, We aim to map and interpret the spectral variations in one such extreme T Tauri star, namely RU Lupi, and to explore how the changes are related to stellar brightness and rotational phase. Methods. We followed the star over three observing runs, each covering a few days, collecting high-resolution optical spectra,In connection to the third run, complementary NIR spectra, multicolour photometric data, and X-ray observations were obtained,Results,The stellar photospheric absorption line spectrum is weakened by superimposed emission, and this veiling becomes extremely high on occasion, Interpreted as a variable continuous excess emission, its contribution would amount to several times the stellar continuum brightness, However, the stellar brightness does not change much when the veiling changes, and we conclude that the veiling is dominated by narrow line emission that fills in the photospheric lines, Continuous emission, originating at the hot spot on the stellar surface, plays a dominant role only at lower degrees of veiling, The radial velocity of narrow emission components in lines of He I vary periodically in anti-phase with the stellar velocity, reflecting the location and motion of the accretion footprint, The blue-shifted wings in He I, related to a stellar wind, are remarkably stable in equivalent width, This implies that the line flux responds directly to changes in the veiling, which in turn is related to the accretion rate close to the star, In contrast, the equivalent widths of the red-shifted wings change with rotational phase, From the pattern of variability we infer that these wings originate in accreting gas close to the star, and that the accretion funnels are bent and trail the hot spot, The profiles of the forbidden lines of [O I] and [S II] are very stable in strength and shape over the entire observing period, and like a system of narrow, blue-shifted absorption features seen in lines of Ca II and Na I, they originate at larger distances from the star in the disk wind,Slightly blue-shifted emission components are present in the forbidden lines and might be related to a wide angle molecular disk wind proposed by others. [ABSTRACT FROM AUTHOR]

Abstract: Motivated by a recent experimental observation of a nodal liquid on both single crystals and thin films of Bi2Sr2CaCu2O8+ δ by Chatterjee et al. [Nature Phys. 6 (2010) 99], we perform a field-theoretical renormalization group (RG) analysis of a two-dimensional model such that only eight points located near the “hot spots” on the Fermi surface are retained, which are directly connected by spin density wave ordering wavevector. We derive RG equations up to two-loop order describing the flow of renormalized couplings, quasiparticle weight, several order-parameter response functions, and uniform spin and charge susceptibilities of the model. We find that while the order-parameter susceptibilities investigated here become non-divergent at two loops, the quasiparticle weight vanishes in the low-energy limit, indicating a breakdown of Fermi liquid behavior at this RG level. Moreover, both uniform spin and charge susceptibilities become suppressed in the scaling limit which indicate gap openings in both spin and charge excitation spectra of the model. [Copyright &y& Elsevier]

We present the results of a newglobal radiation transport code coupled to a general relativistic magnetohydrodynamic simulation of an accreting, non-rotating black hole. For the first time, we are able to explain from first principles in a self-consistent way all the components seen in the X-ray spectra of stellar-mass black holes, including a thermal peak and all the features associated with strong hard X-ray emission: a power law extending to high energies, a Compton reflection hump, and a broad iron line. Varying only the mass accretion rate, we are able to reproduce a wide range of X-ray states seen in most galactic black hole sources. The temperature in the corona is Te ∼ 10 keV in a boundary layer near the disk and rises smoothly to Te ≳ 100 keV in low-density regions far above the disk. Even as the disk’s reflection edge varies from the horizon out to ≈6M as the accretion rate decreases, we find that the shape of the Fe Kα line is remarkably constant. This is because photons emitted from the plunging region are strongly beamed into the horizon and never reach the observer. We have also carried out a basic timing analysis of the spectra and find that the fractional variability increases with photon energy and viewer inclination angle, consistent with the coronal hot spot model for X-ray fluctuations. [ABSTRACT FROM AUTHOR]

Abstract: We present an updated analysis of Jupiter’s equatorial meteorology from Cassini observations. For two months preceding the spacecraft’s closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5μm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like ‘scooter’ clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150–200ms−1, much faster than the 100ms−1 hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed. [Copyright &y& Elsevier]

The results of longitudinal magnetic field measurements B in the hot accretion spot in three classical T Tauri stars (CTTS) are reported. In all three stars the magnetic field is detected at a level above 2 σ in the formation region of the narrow component of the He I 5876 Å emission line. In the case of DS Tau the longitudinal field B in the hot spot was also measured from the narrow emission components of the Na I D lines, implying +0.8 ± 0.3 kG, which is equal to the B field component measured from the He I 5876 Å line. Our results suggest that the 6-m telescope of the Special Astrophysical Observatory can be used to study magnetic fields in the hot spots of CTTS with magnitudes down to 13, making it possible to double the number of stars of this type with measured B values in the accretion zone. [ABSTRACT FROM AUTHOR]

The purpose of this study is to solve the problem of low achievement in fabricating sandwich surface-enhanced Raman scattering (SERS) substrates. We demonstrated a highly efficient sandwich structure by the oriented assembly of metal nanoparticles (NPs) on a periodic hexagonal array of metal nanoprisms with 1,4-benzenedithiol (1,4-BDT) as linkers. The metal nanoprism array was prepared by vacuum deposition of metal on a close-packed polystyrene nanosphere pre-patterned substrate. The metal nanoprism array presents different surface properties from the pits left from the removal of polystyrene nanospheres, which causes linkers to selectively adsorb on the metal nanoprism array and sequentially leads to the oriented immobilization of the second-layer metal NPs, avoiding mismatched orientation. These sandwich SERS substrates were characterized by extinction spectroscopy and atomic force microscopy and their enhancement activity was evaluated under different excitation wavelengths. The sandwich structure greatly increases the achievement of 'hot spots' to almost 100% of all the metal nanoprisms and enables a large amplification of SERS signals by a factor of ten. This method has the advantages of simplicity, high efficiency, high throughput, controllability and high reproducibility. It has significance in both the study of SERS substrates and the development of plasmonic devices. [ABSTRACT FROM AUTHOR]

Owing to the huge potential impact of precipitation extremes on society, it is important to better understand the mechanisms causing these events, and their variations with respect to a changing climate. In this study, the importance of a particular category of weather systems, namely cyclones, for the occurrence of regional-scale precipitation extremes is quantified globally using the ECMWF Interim reanalysis (ERA-Interim) dataset. Such an event-based climatological approach complements previous case studies, which established the physical relationship between cyclones and heavy precipitation. A high percentage of precipitation extremes is found to be directly related to cyclones. Regional hot spots are identified where this percentage of cyclone-induced precipitation extremes exceeds 80% (e.g., in the Mediterranean region, Newfoundland, near Japan, and over the South China Sea). The results suggest that in these regions changes of heavy precipitation with global warming are specifically sensitive to variations in the dynamical forcing, for example, related to shifts of the storm tracks. Furthermore, properties of cyclones causing extreme precipitation are investigated. In the exit regions of the Northern Hemisphere storm tracks, these cyclones are on average slightly more intense than low pressure systems not associated with precipitation extremes, but no differences with respect to minimum core pressure are found in most other parts of the midlatitudes. The fundamental linkage between cyclones and precipitation extremes may thus provide guidance to forecasters involved in flood prediction, but it is unlikely that forecasting rules based on simple cyclone properties can be established. [ABSTRACT FROM AUTHOR]

It is shown that composite radio spectra of the hot spots of the radio galaxy Cygnus A can be fully explained by assuming a nonuniform distribution of the magnetic fields inside the hot spots, without invoking any physical mechanisms other than synchrotron radiation. The magnetic fields are strong ( B ∼ 10−10 G) at the center of the hot spots, and decreases at the hot-spot edges to the level of the magnetic field of the radio lobes in which the hot spots are embedded ( B ∼ 10−10 G). The difference in the magnetic field between the hot-spot center and edge decreases during the evolution, while the average magnetic-field intensity increases. [ABSTRACT FROM AUTHOR]

Recent observations of the central compact object in the Kesteven 79 supernova remnant show that this neutron star (NS) has a weak dipole magnetic field (a few x 1010 G) but an anomalously large (~64%) pulse fraction in its surface X-ray emission. We explore the idea that a substantial sub-surface magnetic field exists in the NS crust, which produces diffuse hot spots on the stellar surface due to anisotropic heat conduction, and gives rise to the observed X-ray pulsation. We develop a general-purpose method, termed "Temperature Template with Full Transport" (TTFT), that computes the synthetic pulse profile of surface X-ray emission from NSs with arbitrary magnetic field and surface temperature distributions, taking into account magnetic atmosphere opacities, beam pattern, vacuum polarization, and gravitational light bending. We show that a crustal toroidal magnetic field of order a few x 1014 G or higher, varying smoothly across the crust, can produce sufficiently distinct surface hot spots to generate the observed pulse fraction in the Kes 79 NS. This result suggests that substantial sub-surface magnetic fields, much stronger than the "visible" dipole fields, may be buried in the crusts of some young NSs, and such hidden magnetic fields can play an important role in their observational manifestations. The general TTFT tool we have developed can also be used for studying radiation from other magnetic NSs. [ABSTRACT FROM AUTHOR]

The article focuses on a study on motion of photons in the equatorial plane of Schwarzschild backgrounds of black hole which are affected by radiation drag. It informs about the calculation of the signal produced by hot spot moving in a Schwarzschild metric under the influence of a radiation field. It informs that all photons in the radiation field possess the same angular momentum and travel along metric spaces. It discusses the result which depicts astrophysical applications.

Abstract: Recent measurements of the surface magnetic fields of classical T Tauri stars (CTTSs) and magnetic cataclysmic variables show that their magnetic fields have a complex structure. Investigation of accretion onto such stars requires global three-dimensional (3D) magnetohydrodynamic (MHD) simulations, where the complexity of simulations strongly increases with each higher-order multipole. Previously, we were able to model disc accretion onto stars with magnetic fields described by a superposition of dipole and quadrupole moments. However, in some stars, like CTTS V2129 Oph and BP Tau, the octupolar component is significant and it was necessary to include the next octupolar component. Here, we show results of global 3D MHD simulations of accretion onto stars with superposition of the dipole and octupole fields, where we vary the ratio between components. Simulations show that if octupolar field strongly dominates at the disc-magnetosphere boundary, then matter flows into the ring-like octupolar poles, forming ring-shape spots at the surface of the star above and below equator. The light-curves are complex and may have two peaks per period. In case where the dipole field dominates, matter accretes in two ordered funnel streams towards poles, however the polar spots are meridionally-elongated due to the action of the octupolar component. In the case when the fields are of similar strengths, both, polar and belt-like spots are present. In many cases the light-curves show the evidence of complex fields, excluding the cases of small inclinations angles, where sinusoidal light-curve is observed and ‘hides’ the information about the field complexity. We also propose new mechanisms of phase shift in stars with complex magnetic fields. We suggest that the phase shifts can be connected with: (1) temporal variation of the star’s intrinsic magnetic field and subsequent redistribution of main magnetic poles; (2) variation of the accretion rate, which causes the disc to interact with the magnetic fields associated with different magnetic moments. We use our model to demonstrate these phase shift mechanisms, and we discuss possible applications of these mechanisms to accreting millisecond pulsars and young stars. [Copyright &y& Elsevier]

Abstract: Global night-time fire counts for the years from 1995 to 2009 have been obtained by using the latest version of Along Track Scanning Radiometer Top of Atmosphere radiance products (level 1B), and related trends have been estimated. Possible biases due to cloud coverage variations have been assumed to be negligible. The sampling number (acquisition frequency) has also been analysed in detail and proved not to influence our results. The new ATSR World Fire Atlas (WFA) product continuity has been tested by comparing the partially overlapping fire counts time series from the ATSR-2 (on board ERS-2) and the AATSR (on board ENVISAT) missions which showed negligible offsets. The ATSR-WFA products show very good correlation with the TRMM-VIRS and MODIS-Aqua/Terra monthly night-time fire counts. Global night-time fire trends have been evaluated by inspecting the time series of hot spots aggregated a) at 2°×2° scale; b) at district/country/region/continent scales, and c) globally. The statistical significance of the estimated trend parameters has been verified by means of the Mann–Kendall test. Results indicate that no trends in the absolute number of fire counts can be identified at the global scale, that there has been no appreciable shift in the fire season during the last 14years, and that statistically significant positive and negative trends are only found when data are aggregated at smaller scales. [Copyright &y& Elsevier]

The presence of Extremely Low Frequency (ELF) from electronic devices such as personal computers, laboratory equipment and television sets in selected laboratories and offices at the College of Science and Technology Building, Covenant University, Ota, Nigeria was characterized using an ELF Detection Meter. The study revealed that exposure to ELF fields could be controlled to the minimum depending on the awareness of the occupant. As with all electromagnetic fields, the ELF field decays rapidly with distance from source or hot spots. The average observed value of ELF in the offices ranged from 3.5 to 5.0 mG. A significant hot spot with ELF of approximately 10 mG in an office was detected close to the magnetic board fixed on the wall. From the results, the maximum ELF fields of between 30-50 mG were observed close to some electronic devices, while other areas recorded significant ELF fields of between 4 mG and 25 mG due to the presence of electrical internal conduit wiring with no electrical gadgets in their vicinities. Minimum ELF fields of between 0.1 mG and 0.5 mG were observed in one of the locations surveyed. [ABSTRACT FROM AUTHOR]