hot spot

Top PDF hot spot:

Analysis of hot spot directional signatures measured from space

Analysis of hot spot directional signatures measured from space

as a result of correlated probabilities of transmission in the incoming and reflected paths within the canopy and soil. On the other hand, a rough surface may also generate a reflectance maximum in the backscattering direction, even if the sun rays do not penetrate it. For instance, an horizontal surface with a few vertical walls produces a broad reflectance increase toward the backscattering direc- tion [Roujean et al., 1992]. The effect of the tree-scale structure of a canopy on the reflectance is similar to the roughness effect. Its physics is rather different from that of the correlated transmissions within the canopy, and may involve multiple scattering. The geometries involved in the two processes have similar vertical scales (the canopy depth), when the horizontal scales are very differ- ent (leaf size versus intercrown distance). The directional signature characteristic angle is related to the ratio of horizontal and vertical scales [Chen and Leblanc, 1997]. Thus we suggest that the directional signature observed within a few degrees is the result of correlated trans- mission, and that the broader shape, over tens of degrees, is generated by the roughness of the canopy. In the following, we focus on the directional signature for the smallest phase angles, which we refer to as the ‘‘hot spot’’. This is of course an idealistic view. For example, in a forest stand, the shape of the hot spot is determined by different levels of canopy structural hierarchy [Chen and Leblanc, 1997]: tree distribution pattern, crown size and shape, branches, shoots and leaves, each of these elements contributing to the hot spot feature with various characteristic widths, from 0.05 for needles to several degrees for the tree structure.
Show more

16 Read more

P-wave tomography of eastern North America: Evidence for mantle evolution from Archean to Phanerozoic, and modification during subsequent hot spot tectonism

P-wave tomography of eastern North America: Evidence for mantle evolution from Archean to Phanerozoic, and modification during subsequent hot spot tectonism

[ 50 ] Northwest of the Grenville–Superior boundary, the Archean portion of our study area shows no evidence for low wave speed anomalies along the proposed Great Meteor hot spot track. The only record of the hot spot magmatism in the Superior craton is the presence of kimberlite pipes [e.g., Heaman and Kjarsgaard, 2000]. Kimberlite melts are typi- cally small in volume, developing deep within the mantle before rising rapidly towards the surface, causing little modification of the mantle lithosphere en route. The nature of the magmatism, together with the lack of any discernible seismic signature of lithospheric modification along the hot spot track in this region is consistent with the idea of the cratonic keels being intrinsically resistant to pervasive modification or erosion via interaction with plumes, due to their distinct composition, buoyancy and thickness [e.g., Sleep et al., 2002].
Show more

15 Read more

Detailed Analysis of Near Tectonic Features Along the East Pacific Rise at 16°N, Near the Mathematician Hot Spot

Detailed Analysis of Near Tectonic Features Along the East Pacific Rise at 16°N, Near the Mathematician Hot Spot

Laboratoire Géosciences Océan, UBO/UBS/CNRS, IUEM, Plouzané, France, 2 Now at Geomar Helmholtz Centre for Ocean Research, Kiel, Germany, 3 École Navale, IRENav, Brest, France Abstract Spreading processes at the axes of fast spreading ridges are mainly controlled by magmatic activity, whereas tectonic activity dominates further away from the axis. High-resolution near-bottom bathymetry data, photographs, videos, and human observations from submersible surveys are used to develop a detailed tectonic analysis of the 16°N segment of the East Paci fic Rise (EPR). These data are used to evaluate how a highly magmatic segment, close to a hot spot, affects the nucleation and evolution of faulting patterns and impacts the evaluation of tectonic strain within 2 km of the spreading axis. Our study shows that (1) the growth of tectonic features differs in response to dike intrusion and tectonic extension, (2) the initiation of brittle extension is strongly controlled by the location of the axial magma lens and the development of layer 2A, and (3) the high magmatic budget and the off-axis magma lens in the west part of the plateau do not signi ficantly impact the initiation of brittle extension along the central portion of the 16°N segment. Within the axial summit region, more than 2% of plate separation at 16°N on the EPR is
Show more

23 Read more

Strong competition between $\Theta_{II}$-loop-current order and $d$-wave charge order along the diagonal direction in a two-dimensional hot spot model

Strong competition between $\Theta_{II}$-loop-current order and $d$-wave charge order along the diagonal direction in a two-dimensional hot spot model

At this point, we would like to point out that we will consider only the lowest energy band of the noninteract- ing Hamiltonian defined in Eq. ( 1 ). For physically mo- tivated choices of the parameters in the present model, the low-energy band will naturally give rise to a Fermi surface shown in Fig. 3 . The most singular contribu- tion in this effective model will arise from the points at the Fermi surface (the so-called hot spots) that represents the intersection of this surface with the antiferromagnetic zone boundary. Therefore, we will restrict the analysis of the present model to the vicinity of these important hot spot points in the considerations that follow. With this in mind and to set up our notation, we now define the following 16-component fermionic spinors
Show more

17 Read more

Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA

Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA

DOI: 10.1103/PhysRevLett.117.025001 The spherical concentric layers of a direct-drive inertial confinement fusion (ICF) target nominally consist of a central region of a near-equimolar deuterium and tritium (DT) vapor surrounded by a cryogenic DT-fuel layer and a thin, nominally plastic (CH) ablator. The outer surface of the ablator is uniformly irradiated with multiple laser beams having a peak overlapped intensity of <10 15 watts=cm 2 . The resulting laser-ablation process causes the target to accelerate and implode. As the DT-fuel layer decelerates, the initial DT vapor and the fuel mass thermally ablated from the inner surface of the ice layer are compressed and form a central hot spot, in which fusion reactions occur. ICF relies on the 3.5-MeV DT-fusion alpha particles depositing their energy in the hot spot, causing the hot- spot temperature to rise sharply and a thermonuclear burn wave to propagate out through the surrounding nearly degenerate, cold, dense DT fuel, producing significantly more energy than was used to heat and compress the fuel. Ignition is predicted to occur when the product of the temperature and areal density of the hot spot reach a minimum of 5 keV × 0.3 g=cm 2 [1 –3] .
Show more

6 Read more

The R304X mutation of the Aryl hydrocarbon receptor Interacting Protein gene in familial isolated pituitary adenomas: mutational Hot-Spot or founder effect?

The R304X mutation of the Aryl hydrocarbon receptor Interacting Protein gene in familial isolated pituitary adenomas: mutational Hot-Spot or founder effect?

Genotyping Because the AIP R304X mutation was identified in three ap- parently unrelated Italian FIPA families, we wished to find out whether the c.910T mutated allele had a common origin or was the result of a mutational hot-spot. To ad- dress this issue, 12 microsatellite markers around AIP and MEN1 genes were first analyzed in all consenting patients and relatives. In family 1, an at risk haplotype of at least 12 Mb was found to segregate in all mutation carriers. Interestingly, the AIP R304X mutation carriers in family 2,

6 Read more

Renormalization group analysis of the pair-density-wave and charge order within the fermionic hot-spot model for cuprate superconductors

Renormalization group analysis of the pair-density-wave and charge order within the fermionic hot-spot model for cuprate superconductors

V. CONCLUSIONS In the present work, we have investigated within a complete two-loop RG framework the fermionic hot spot model relevant to the phenomenology of the cuprates, which describes excitations with a linearized dispersion in the vicinity of eight hot spots (i.e., the points in mo- mentum space in which the AF zone boundary intersects a putative underlying Fermi surface of the cuprate su- perconductors at low hole doping). The present model can be seen as descendant of the Abanov-Chubukov spin- fermion model that, most importantly, includes here all relevant interactions between the fermions and, for this reason, allows one to investigate on equal footing all of its possible instabilities from a weak to moderate coupling regime.
Show more

13 Read more

Badlands as a hot spot of petrogenic contribution to riverine particulate organic carbon to the Gulf of Lion (NW Mediterranean Sea)

Badlands as a hot spot of petrogenic contribution to riverine particulate organic carbon to the Gulf of Lion (NW Mediterranean Sea)

6. Discussion 6.1 SPM fluxes delivered by the Rhône River: contribution of the Durance River and the badlands hot spot The Durance River significantly contributes to the SPM fluxes delivered to the Gulf of Lion (Sadaoui et al., 2016). These last authors report the major role of sedimentary rocks outcropping in the mountains (e.g., the Alps and Pyrénées) as a source of the solid fluxes delivered by coastal rivers to the Mediterranean Sea (Sadaoui et al., 2016). By using a model based on sedimentary mass balance, these authors estimated that the Durance River contributes 23 % of the SPM flux transported by the Rhône River. Furthermore, Zebracki et al. (2015) used geogenic radionuclides as fingerprints of sedimentary masses transported during flood events to estimate that the Pre-Alpine tributaries (Durance, Ouvèze, Aigues, fig. 1) would account for 38 to 53% of the SPM flux delivered by the Rhône River. In our study, the Durance River contribution to the SPM load of the Rhône River is estimated at 32% (fig. 7B), which agrees well with these previous estimates.
Show more

55 Read more

A computational tool to predict the evolutionarily conserved protein-protein interaction hot-spot residues from the structure of the unbound protein

A computational tool to predict the evolutionarily conserved protein-protein interaction hot-spot residues from the structure of the unbound protein

computational methods to be lower than the true coverage. Second, a lack of exhaustive experimental data on the identification of all hot-spot residues of a protein leads to lower observed accuracy of the predictive computational methods than their true accuracy. In fact, for the proteins that we studied, experimental mutagenesis data were lacking for a number of binding-region residues, and this lack of data is reflected by a large difference between the accuracy and the theoretical maximum accuracy of hot-spot residue prediction in our analysis. Third, any computational tool that is based on the structure of the unbound protein will fail to account for the conformational change in the structure of the protein upon binding to its receptor. Although simple molecular-dynamics simulations can account for some of the protein flexibility around the unbound conformation, advanced molecular simulation techniques must be used to observe large protein conformational changes in these simulations.
Show more

34 Read more

Hot spot of N 2 fixation in the western tropical South Pacific pleads for a spatial decoupling between N 2 fixation and denitrification

Hot spot of N 2 fixation in the western tropical South Pacific pleads for a spatial decoupling between N 2 fixation and denitrification

cific (ETSP), seriously bringing into question the pro- posed close spatial coupling between N input (through N 2 fixation) and loss (through denitrification) (3). Here, we compile data from recently published and unpublished studies revealing a hot spot of N 2

3 Read more

Heterogeneity in southern Central Indian Ridge MORB: implications for ridge-hot spot interaction.

Heterogeneity in southern Central Indian Ridge MORB: implications for ridge-hot spot interaction.

elevated incompatible element concentrations and ratios (including elevated H 2 O, lower Fe [8] , and higher Al [8] ). In addition, the northernmost samples are relatively enriched in strontium and have heavy REE to middle REE depletion. To the south, the samples resemble normal MORB. These form the depleted end of a mixing line that includes the northern basalts at its enriched end and whose compositions overlap the field for La Re´union Island tholeiites. After testing to what extent the enrichment is a function of varying conditions of crystal fractionation, plagioclase assimilation or mantle melting (including hydrous melting), we conclude it is caused by mixing between depleted asthenosphere (yielding normal MORB in the south) and mantle from the Re´union hot spot. This requires hot spot asthenosphere to migrate east- ward away from La Re´union and toward the CIR, against the motion of the lithosphere, over a distance of 1100 km. While the initial depth of mantle melting increases northward along the CIR, it remains shallower than beneath La Re´union, suggesting that the eastward flowing hot spot mantle cools during its migration toward the ridge. However, the hot spot mantle that reaches the CIR retains its incompatible element content and vola- tile hydrous phase, and hence is not depleted by melting en route. Thus the influence of Re´union hot spot mantle on the CIR remains compelling evidence for active migration of hot spot material from La Re´union to the spreading ridge, over a distance of 1100 km.
Show more

25 Read more

Implications for Deriving Regional Fossil Fuel CO 2 Estimates from Atmospheric Observations in a Hot Spot of Nuclear Power Plant 14 CO 2 Emissions

Implications for Deriving Regional Fossil Fuel CO 2 Estimates from Atmospheric Observations in a Hot Spot of Nuclear Power Plant 14 CO 2 Emissions

2 emission data on daily or synoptic timescale would be desirable. This seems unrealistic at the moment, but weekly to monthly average 14 CO 2 emissions might be feasible for many sites and would decrease the uncertainty of FFCO 2,mask and help to identify situations where the observational data needs to be flagged. Until these high-resolution emission inventories are available, data flagging might be an option for sites within hot spot regions (like Egbert), as the signal is noticeable in the observed 14 C time series. Identifying such periods at sites further downwind of the nuclear power plant site will, however, be challenging. Although the effect will be smaller there, it, if not accounted for, can still cause a (significant) bias in the fossil fuel CO 2 estimate. This is especially noteworthy as the highly populated regions e.g. the NE coast of America can be affected by CANDU and other nuclear reactors. Previous studies estimated that the emissions of the nuclear industry account for a masking of about 0.2–0.8 ppm FFCO 2 (monthly average) for a site downwind of Ontario (Miller et al. 2012) or ratios of FFCO 2,mask to FFCO 2 of 0–90% (Graven and Gruber 2011). Our study suggests that the influence of Canadian CANDU reactors should be expected to be at the upper end of this range.
Show more

19 Read more

The Amsterdam-St. Paul Plateau: A complex hot spot/DUPAL-flavored MORB interaction

The Amsterdam-St. Paul Plateau: A complex hot spot/DUPAL-flavored MORB interaction

rapprochement of a ridge and a hot spot, has been observed in some seamounts of the Foundation chain [Maia et al., 2000]. It is therefore conceivable that the same process may have occurred when the early CDP seamounts formed. The second seamount generation (<2.1 Ma) displays much more variable isotopic signatures and the youngest seamount even exhibits the most extreme composition among our new data set. Apollinaire is therefore, in composition, the closest sample to ASP hot spot end-member. Considering those samples as repre- sentative of the bulk composition of the seamounts, we can explain this observation as follows: (1) the large old seamounts may result from larger degrees of melting, and therefore exhibit a more dilute enriched signature because of mixing with local depleted mantle melts and (2) the youngest sea- mounts, which formed above lithospheric cracks [Janin et al., 2011], would result from lower degrees of melting of more enriched materiel left by the plume under or in the lithosphere. Maia et al. [2011] suggested an episodic activity of ASP mantle plume. In the frame of Maia et al. models, the youngest seamounts are related to the second pulse which constructed the ASP plateau [Janin et al., 2011]. Some plume material could have been ponded underneath the plateau, enhancing melt eruption through a weaker lithosphere, and the construction of the young seamounts along the Capricorn and Australian plate diverging boundary. Such material migration can occur prior or after the plume melting, that is to say in a solid or liquid state. The survival of extreme isotope signature, and the survival small scales heterogeneities within a single seamount, rather suggest a solid state for
Show more

27 Read more

Recent and present-day tectonics near a hot spot : the transform zones of iceland

Recent and present-day tectonics near a hot spot : the transform zones of iceland

To conclude, Iceland provides a unique opportunity to compare immature and mature transform zones on land (totally in the SISZ, partly in the TFZ) and using seismological data. This comparison demonstrates that the trend of the transform motion, as reflected in the major features, is hidden at the beginning of the transform process and develops when the transform zone becomes mature. The geometry related to the immature stage shows a diffuse shear zone with a Riedel-type pattern of faults, with a dominating stress field that reflects the behaviour of the transform zone. At the mature stage, the geometry becomes simpler, with the development of a well-localised shear fault zone where most of the transform process concentrates, but a complex stress pattern prevails with major variations in friction along the fault and different stress states that reflect abrupt changes in mechanical coupling, probably as a function of the major magmatic crises. To this respect, it is likely that not only does the Icelandic hot spot induce rift jumps; it also significantly influences the behaviour of the transform faults.
Show more

7 Read more

ACCRETION TORQUES AND MOTION OF THE HOT SPOT ON THE ACCRETING MILLISECOND PULSAR XTE J1807-294

ACCRETION TORQUES AND MOTION OF THE HOT SPOT ON THE ACCRETING MILLISECOND PULSAR XTE J1807-294

and (−0.6, +3.8) × 10 −14 Hz s −1 for the fundamental and second harmonics, respectively. The sinusoidal frac- tional amplitudes of the pulsations are the highest observed among AMXPs and can reach values of up to 27% (2.5–30 keV). The pulse arrival time residuals of the fundamental frequency follow a linear anti-correlation with the fractional amplitudes that suggests hot spot motion both in longitude and latitude over the surface of the neutron star. An anti-correlation between residuals and X-ray flux suggests an influence of the accretion rate on pulse phase and casts doubts on the interpretation of pulse frequency derivatives in terms of changes of spin rates and torques on the neutron star.
Show more

10 Read more

Land cover composition, local plant community composition and honeybee colony density affect wild bee species assemblages in a Mediterranean biodiversity hot-spot

Land cover composition, local plant community composition and honeybee colony density affect wild bee species assemblages in a Mediterranean biodiversity hot-spot

Our objectives were (i) to assess the composition of the wild bee species assemblages, and (ii) to explore the e ffect of a) land cover composition (anthropogenic zone, low scrubland, for[r]

11 Read more

Crustal thickness of V-shaped ridges south of the Azores: Interaction of the Mid-Atlantic Ridge (36°-39°N) and the Azores hot spot

Crustal thickness of V-shaped ridges south of the Azores: Interaction of the Mid-Atlantic Ridge (36°-39°N) and the Azores hot spot

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignemen[r]

18 Read more

Using Activated Transport in Parallel Nanowires for Energy Harvesting and Hot Spot Cooling

Using Activated Transport in Parallel Nanowires for Energy Harvesting and Hot Spot Cooling

also found to reach promising values Z e T ≈ 3 when Q is maximal [see Fig. 3(b)]. Furthermore, we discuss how the phononic thermal conductance K ph will inevitably reduce the full figure of merit ZT and argue that, even if record high ZT is probably not to be sought in such setups, the latter have the great advantage of offering at once high output power and reasonable efficiency with standard nanotechnology building blocks. The most im- portant result of this paper is given in Sec. V. We study how deposited NWs in the FET configuration can be used to manage heat in the substrate, generating hot/cold spots “on demand”. The idea is simple to grasp and re- lies on the calculation of the local heat exchanges between the NWs electrons and the substrate phonons: When the gate voltage is adjusted such that the equilibrium electro- chemical potential µ (defined in the electronic reservoirs) roughly coincides with one (say the lower) impurity band edge, basically all energy states in the NWs lie above µ. Therefore, if charge carriers injected into the system around µ are to gain the other end, they need to (on the average) absorb phonons at the entrance so as to jump to available states, and then to release phonons when tun- neling out (again at µ). This generates in the nearby substrate regions cold strips near the injecting electrode and hot strips near the drain electrode [see Figs. 1(b) and 4]. These strips get scrambled along the nanowires if µ does not probe the edges of the NWs impurity band. Such reliable and tunable cold spots may be exploited in devising thermal management tools for high-density cir- cuitry, where ever increasing power densities have become a critical issue. 51 Moreover, the creation/annihilation of
Show more

13 Read more

XCO2 in an emission hot-spot region: the COCCON Paris campaign 2015

XCO2 in an emission hot-spot region: the COCCON Paris campaign 2015

The calibration measurements for this campaign were performed in Karlsruhe using the Total Carbon Column Ob- serving Network (TCCON) (Wunch et al., 2011) spectrome- ter at the Karlsruhe [r]

16 Read more

A Hot-spot of In-frame Duplications Activates the Oncoprotein AKT1 in Juvenile Granulosa Cell Tumors

A Hot-spot of In-frame Duplications Activates the Oncoprotein AKT1 in Juvenile Granulosa Cell Tumors

Fig. Mutated AKT1 phosphorylation and activation levels. A) Western-blot analysis of the phosphorylation levels of several AKT1 variants (wild-type/WT, E17K and 4 elongated pro- teins). [r]

12 Read more

Show all 636 documents...