Infrared polar brightenings on Jupiter. V - A thermal equilibrium model for the north polar hot spot

NASA Technical Reports Server (NTRS)

Halthore, Rangasayi; Burrows, Adam; Caldwell, John

1988-01-01

Voyager IRIS instrument records of the IR hydrocarbon emissions from Jupiter's north polar region are presently studied to determine the spatial and other characteristics of the north polar hot spot. Attention is given to a thermal equilibrium model that exploits the asymmetry found in 7.8-micron emission of stratospheric methane with respect to system III longitude in order to estimate stratospheric zonal wind velocity. This model accurately predicts the observed asymmetry in acetylene's 13.6-micron emission; this requires, however, enhanced acetylene abundance in the hot spot, as well as ethane depletion. Energetic charged particles are suggested to be the most probable cause of these effects.

First Liquid Layer Inertial Confinement Fusion Implosions at the National Ignition Facility

DOE PAGES

Olson, R. E.; Leeper, R. J.; Kline, J. L.; ...

2016-12-07

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D 2 and DT layer Inertial Confinement Fusion (ICF) implosions that can access low-to-moderate hot spot convergence ratio (1230) DT ice layer implosions. Although high CR is desirable in an idealized 1D sense, it amplifies the deleterious effects of asymmetries. To date, these asymmetries prevented the achievement of ignition at the NIF and are the major cause of simulation-experiment disagreement. In the initial liquid layer experiments, high neutron yields were achieved with CR’s of 12-17, and the hot spot formation is well understood, demonstratedmore » by good agreement between the experimental data and the radiation hydrodynamic simulations. These initial experiments open a new NIF experimental capability that provides an opportunity to explore the relationship between hot-spot convergence ratio and the robustness of hot-spot formation during ICF implosions.« less

First Liquid Layer Inertial Confinement Fusion Implosions at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Olson, R. E.; Leeper, R. J.; Kline, J. L.; Zylstra, A. B.; Yi, S. A.; Biener, J.; Braun, T.; Kozioziemski, B. J.; Sater, J. D.; Bradley, P. A.; Peterson, R. R.; Haines, B. M.; Yin, L.; Berzak Hopkins, L. F.; Meezan, N. B.; Walters, C.; Biener, M. M.; Kong, C.; Crippen, J. W.; Kyrala, G. A.; Shah, R. C.; Herrmann, H. W.; Wilson, D. C.; Hamza, A. V.; Nikroo, A.; Batha, S. H.

2016-12-01

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D2 and DT layer inertial confinement fusion (ICF) implosions that can access a low-to-moderate hot-spot convergence ratio (12 30 ) DT ice layer implosions. Although high CR is desirable in an idealized 1D sense, it amplifies the deleterious effects of asymmetries. To date, these asymmetries prevented the achievement of ignition at the NIF and are the major cause of simulation-experiment disagreement. In the initial liquid layer experiments, high neutron yields were achieved with CRs of 12-17, and the hot-spot formation is well understood, demonstrated by a good agreement between the experimental data and the radiation hydrodynamic simulations. These initial experiments open a new NIF experimental capability that provides an opportunity to explore the relationship between hot-spot convergence ratio and the robustness of hot-spot formation during ICF implosions.

Minimizing hot spot temperature in asymmetric gradient coil design.

PubMed

While, Peter T; Forbes, Larry K; Crozier, Stuart

2011-08-01

Heating caused by gradient coils is a considerable concern in the operation of magnetic resonance imaging (MRI) scanners. Hot spots can occur in regions where the gradient coil windings are closely spaced. These problem areas are particularly common in the design of gradient coils with asymmetrically located target regions. In this paper, an extension of an existing coil design method is described, to enable the design of asymmetric gradient coils with reduced hot spot temperatures. An improved model is presented for predicting steady-state spatial temperature distributions for gradient coils. A great amount of flexibility is afforded by this model to consider a wide range of geometries and system material properties. A feature of the temperature distribution related to the temperature gradient is used in a relaxed fixed point iteration routine for successively altering coil windings to have a lower hot spot temperature. Results show that significant reductions in peak temperature are possible at little or no cost to coil performance when compared to minimum power coils of equivalent field error.

First Liquid Layer Inertial Confinement Fusion Implosions at the National Ignition Facility.

PubMed

Olson, R E; Leeper, R J; Kline, J L; Zylstra, A B; Yi, S A; Biener, J; Braun, T; Kozioziemski, B J; Sater, J D; Bradley, P A; Peterson, R R; Haines, B M; Yin, L; Berzak Hopkins, L F; Meezan, N B; Walters, C; Biener, M M; Kong, C; Crippen, J W; Kyrala, G A; Shah, R C; Herrmann, H W; Wilson, D C; Hamza, A V; Nikroo, A; Batha, S H

2016-12-09

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D_{2} and DT layer inertial confinement fusion (ICF) implosions that can access a low-to-moderate hot-spot convergence ratio (1230) DT ice layer implosions. Although high CR is desirable in an idealized 1D sense, it amplifies the deleterious effects of asymmetries. To date, these asymmetries prevented the achievement of ignition at the NIF and are the major cause of simulation-experiment disagreement. In the initial liquid layer experiments, high neutron yields were achieved with CRs of 12-17, and the hot-spot formation is well understood, demonstrated by a good agreement between the experimental data and the radiation hydrodynamic simulations. These initial experiments open a new NIF experimental capability that provides an opportunity to explore the relationship between hot-spot convergence ratio and the robustness of hot-spot formation during ICF implosions.

The distribution of hot spots

NASA Technical Reports Server (NTRS)

Stefanick, M.; Jurdy, D. M.

1984-01-01

Statistical analyses are compared for two published hot spot data sets, one minimal set of 42 and another larger set of 117, using three different approaches. First, the earths surface is divided into 16 equal-area fractions and the observed distribution of hot spots among them is analyzed using chi-square tests. Second, cumulative distributions about the principal axes of the hot spot inertia tensor are used to describe hot spot distribution. Finally, a hot spot density function is constructed for each of the two hot spot data sets. The methods all indicate that hot spots have a nonuniform distribution, even when statistical fluctuations are considered. To the first order, hot spots are concentrated on one half of of the earth's surface area; within that portion, the distribution is consistent with a uniform distribution. The observed hot spot densities for neither data set are explained solely by plate speed.

Designing gradient coils with reduced hot spot temperatures.

PubMed

While, Peter T; Forbes, Larry K; Crozier, Stuart

2010-03-01

Gradient coil temperature is an important concern in the design and construction of MRI scanners. Closely spaced gradient coil windings cause temperature hot spots within the system as a result of Ohmic heating associated with large current being driven through resistive material, and can strongly affect the performance of the coils. In this paper, a model is presented for predicting the spatial temperature distribution of a gradient coil, including the location and extent of temperature hot spots. Subsequently, a method is described for designing gradient coils with improved temperature distributions and reduced hot spot temperatures. Maximum temperature represents a non-linear constraint and a relaxed fixed point iteration routine is proposed to adjust coil windings iteratively to minimise this coil feature. Several examples are considered that assume different thermal material properties and cooling mechanisms for the gradient system. Coil winding solutions are obtained for all cases considered that display a considerable drop in hot spot temperature (>20%) when compared to standard minimum power gradient coils with equivalent gradient homogeneity, efficiency and inductance. The method is semi-analytical in nature and can be adapted easily to consider other non-linear constraints in the design of gradient coils or similar systems. Crown Copyright (c) 2009. Published by Elsevier Inc. All rights reserved.

Amorphous-silicon module hot-spot testing

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.

1985-01-01

Hot spot heating occurs when cell short-circuit current is lower than string operating current. Amorphous cell hot spot are tested to develop the techniques required for performing reverse bias testing of amorphous cells. Also, to quantify the response of amorphous cells to reverse biasing. Guidelines are developed from testing for reducing hot spot susceptibility of amorphous modules and to develop a qualification test for hot spot testing of amorphous modules. It is concluded that amorphous cells undergo hot spot heating similarly to crystalline cells. Comparison of results obtained with submodules versus actual modules indicate heating levels lower in actual modules. Module design must address hot spot testing and hot spot qualification test conducted on modules showed no instabilities and minor cell erosion.

The rise and fall of a human recombination hot spot.

PubMed

Jeffreys, Alec J; Neumann, Rita

2009-05-01

Human meiotic crossovers mainly cluster into narrow hot spots that profoundly influence patterns of haplotype diversity and that may also affect genome instability and sequence evolution. Hot spots also seem to be ephemeral, but processes of hot-spot activation and their subsequent evolutionary dynamics remain unknown. We now analyze the life cycle of a recombination hot spot. Sperm typing revealed a polymorphic hot spot that was activated in cis by a single base change, providing evidence for a primary sequence determinant necessary, though not sufficient, to activate recombination. This activating mutation occurred roughly 70,000 y ago and has persisted to the present, most likely fortuitously through genetic drift despite its systematic elimination by biased gene conversion. Nonetheless, this self-destructive conversion will eventually lead to hot-spot extinction. These findings define a subclass of highly transient hot spots and highlight the importance of understanding hot-spot turnover and how it influences haplotype diversity.

Relationship between hot spot residues and ligand binding hot spots in protein-protein interfaces.

PubMed

Zerbe, Brandon S; Hall, David R; Vajda, Sandor; Whitty, Adrian; Kozakov, Dima

2012-08-27

In the context of protein-protein interactions, the term "hot spot" refers to a residue or cluster of residues that makes a major contribution to the binding free energy, as determined by alanine scanning mutagenesis. In contrast, in pharmaceutical research, a hot spot is a site on a target protein that has high propensity for ligand binding and hence is potentially important for drug discovery. Here we examine the relationship between these two hot spot concepts by comparing alanine scanning data for a set of 15 proteins with results from mapping the protein surfaces for sites that can bind fragment-sized small molecules. We find the two types of hot spots are largely complementary; the residues protruding into hot spot regions identified by computational mapping or experimental fragment screening are almost always themselves hot spot residues as defined by alanine scanning experiments. Conversely, a residue that is found by alanine scanning to contribute little to binding rarely interacts with hot spot regions on the partner protein identified by fragment mapping. In spite of the strong correlation between the two hot spot concepts, they fundamentally differ, however. In particular, while identification of a hot spot by alanine scanning establishes the potential to generate substantial interaction energy with a binding partner, there are additional topological requirements to be a hot spot for small molecule binding. Hence, only a minority of hot spots identified by alanine scanning represent sites that are potentially useful for small inhibitor binding, and it is this subset that is identified by experimental or computational fragment screening.

PRDM9 variation strongly influences recombination hot-spot activity and meiotic instability in humans.

PubMed

Berg, Ingrid L; Neumann, Rita; Lam, Kwan-Wood G; Sarbajna, Shriparna; Odenthal-Hesse, Linda; May, Celia A; Jeffreys, Alec J

2010-10-01

PRDM9 has recently been identified as a likely trans regulator of meiotic recombination hot spots in humans and mice. PRDM9 contains a zinc finger array that, in humans, can recognize a short sequence motif associated with hot spots, with binding to this motif possibly triggering hot-spot activity via chromatin remodeling. We now report that human genetic variation at the PRDM9 locus has a strong effect on sperm hot-spot activity, even at hot spots lacking the sequence motif. Subtle changes within the zinc finger array can create hot-spot nonactivating or enhancing variants and can even trigger the appearance of a new hot spot, suggesting that PRDM9 is a major global regulator of hot spots in humans. Variation at the PRDM9 locus also influences aspects of genome instability-specifically, a megabase-scale rearrangement underlying two genomic disorders as well as minisatellite instability-implicating PRDM9 as a risk factor for some pathological genome rearrangements.

PRDM9 variation strongly influences recombination hot-spot activity and meiotic instability in humans

PubMed Central

Berg, Ingrid L.; Neumann, Rita; Lam, Kwan-Wood G.; Sarbajna, Shriparna; Odenthal-Hesse, Linda; May, Celia A.; Jeffreys, Alec J.

2011-01-01

PRDM9 has recently been identified as a likely trans-regulator of meiotic recombination hot spots in humans and mice1-3. The protein contains a zinc finger array that in humans can recognise a short sequence motif associated with hot spots4, with binding to this motif possibly triggering hot-spot activity via chromatin remodelling5. We now show that variation in the zinc finger array in humans has a profound effect on sperm hot-spot activity, even at hot spots lacking the sequence motif. Very subtle changes within the array can create hot-spot non-activating and enhancing alleles, and even trigger the appearance of a new hot spot. PRDM9 thus appears to be the preeminent global regulator of hot spots in humans. Variation at this locus also influences aspects of genome instability, specifically a megabase-scale rearrangement underlying two genomic disorders6 as well as minisatellite instability7, implicating PRDM9 as a risk factor for some pathological genome rearrangements. PMID:20818382

Hot spot-based design of small-molecule inhibitors for protein-protein interactions.

PubMed

Guo, Wenxing; Wisniewski, John A; Ji, Haitao

2014-06-01

Protein-protein interactions (PPIs) are important targets for the development of chemical probes and therapeutic agents. From the initial discovery of the existence of hot spots at PPI interfaces, it has been proposed that hot spots might provide the key for developing small-molecule PPI inhibitors. However, there has been no review on the ways in which the knowledge of hot spots can be used to achieve inhibitor design, nor critical examination of successful examples. This Digest discusses the characteristics of hot spots and the identification of druggable hot spot pockets. An analysis of four examples of hot spot-based design reveals the importance of this strategy in discovering potent and selective PPI inhibitors. A general procedure for hot spot-based design of PPI inhibitors is outlined. Copyright © 2014 Elsevier Ltd. All rights reserved.

Relationship between Hot Spot Residues and Ligand Binding Hot Spots in Protein-Protein Interfaces

PubMed Central

Zerbe, Brandon S.; Hall, David R.

2013-01-01

In the context of protein-protein interactions, the term “hot spot” refers to a residue or cluster of residues that makes a major contribution to the binding free energy, as determined by alanine scanning mutagenesis. In contrast, in pharmaceutical research a hot spot is a site on a target protein that has high propensity for ligand binding and hence is potentially important for drug discovery. Here we examine the relationship between these two hot spot concepts by comparing alanine scanning data for a set of 15 proteins with results from mapping the protein surfaces for sites that can bind fragment-sized small molecules. We find the two types of hot spots are largely complementary; the residues protruding into hot spot regions identified by computational mapping or experimental fragment screening are almost always themselves hot spot residues as defined by alanine scanning experiments. Conversely, a residue that is found by alanine scanning to contribute little to binding rarely interacts with hot spot regions on the partner protein identified by fragment mapping. In spite of the strong correlation between the two hot spot concepts, they fundamentally differ, however. In particular, while identification of a hot spot by alanine scanning establishes the potential to generate substantial interaction energy with a binding partner, there are additional topological requirements to be a hot spot for small molecule binding. Hence, only a minority of hot spots identified by alanine scanning represent sites that are potentially useful for small inhibitor binding, and it is this subset that is identified by experimental or computational fragment screening. PMID:22770357

Rigorous assessment and integration of the sequence and structure based features to predict hot spots

PubMed Central

2011-01-01

Background Systematic mutagenesis studies have shown that only a few interface residues termed hot spots contribute significantly to the binding free energy of protein-protein interactions. Therefore, hot spots prediction becomes increasingly important for well understanding the essence of proteins interactions and helping narrow down the search space for drug design. Currently many computational methods have been developed by proposing different features. However comparative assessment of these features and furthermore effective and accurate methods are still in pressing need. Results In this study, we first comprehensively collect the features to discriminate hot spots and non-hot spots and analyze their distributions. We find that hot spots have lower relASA and larger relative change in ASA, suggesting hot spots tend to be protected from bulk solvent. In addition, hot spots have more contacts including hydrogen bonds, salt bridges, and atomic contacts, which favor complexes formation. Interestingly, we find that conservation score and sequence entropy are not significantly different between hot spots and non-hot spots in Ab+ dataset (all complexes). While in Ab- dataset (antigen-antibody complexes are excluded), there are significant differences in two features between hot pots and non-hot spots. Secondly, we explore the predictive ability for each feature and the combinations of features by support vector machines (SVMs). The results indicate that sequence-based feature outperforms other combinations of features with reasonable accuracy, with a precision of 0.69, a recall of 0.68, an F1 score of 0.68, and an AUC of 0.68 on independent test set. Compared with other machine learning methods and two energy-based approaches, our approach achieves the best performance. Moreover, we demonstrate the applicability of our method to predict hot spots of two protein complexes. Conclusion Experimental results show that support vector machine classifiers are quite effective in predicting hot spots based on sequence features. Hot spots cannot be fully predicted through simple analysis based on physicochemical characteristics, but there is reason to believe that integration of features and machine learning methods can remarkably improve the predictive performance for hot spots. PMID:21798070

Druggable orthosteric and allosteric hot spots to target protein-protein interactions.

PubMed

Ma, Buyong; Nussinov, Ruth

2014-01-01

Drug designing targeting protein-protein interactions is challenging. Because structural elucidation and computational analysis have revealed the importance of hot spot residues in stabilizing these interactions, there have been on-going efforts to develop drugs which bind the hot spots and out-compete the native protein partners. The question arises as to what are the key 'druggable' properties of hot spots in protein-protein interactions and whether these mimic the general hot spot definition. Identification of orthosteric (at the protein- protein interaction site) and allosteric (elsewhere) druggable hot spots is expected to help in discovering compounds that can more effectively modulate protein-protein interactions. For example, are there any other significant features beyond their location in pockets in the interface? The interactions of protein-protein hot spots are coupled with conformational dynamics of protein complexes. Currently increasing efforts focus on the allosteric drug discovery. Allosteric drugs bind away from the native binding site and can modulate the native interactions. We propose that identification of allosteric hot spots could similarly help in more effective allosteric drug discovery. While detection of allosteric hot spots is challenging, targeting drugs to these residues has the potential of greatly increasing the hot spot and protein druggability.

Scaling of Liquid DT Layer Capsules to an ICF Burning Plasma

NASA Astrophysics Data System (ADS)

Olson, R. E.; Peterson, R. R.; Haines, B. M.; Yi, S. A.; Bradley, P. A.; Zylstra, A. B.; Kline, J. L.; Leeper, R. J.; Batha, S. H.

2017-10-01

Recent experiments at the NIF demonstrated cryogenic liquid DT layer ICF implosions. Unlike DT ice layer implosions, DT liquid layer designs can operate with low-to-moderate convergence ratio (12

Computational prediction of protein hot spot residues.

PubMed

Morrow, John Kenneth; Zhang, Shuxing

2012-01-01

Most biological processes involve multiple proteins interacting with each other. It has been recently discovered that certain residues in these protein-protein interactions, which are called hot spots, contribute more significantly to binding affinity than others. Hot spot residues have unique and diverse energetic properties that make them challenging yet important targets in the modulation of protein-protein complexes. Design of therapeutic agents that interact with hot spot residues has proven to be a valid methodology in disrupting unwanted protein-protein interactions. Using biological methods to determine which residues are hot spots can be costly and time consuming. Recent advances in computational approaches to predict hot spots have incorporated a myriad of features, and have shown increasing predictive successes. Here we review the state of knowledge around protein-protein interactions, hot spots, and give an overview of multiple in silico prediction techniques of hot spot residues.

Computational Prediction of Hot Spot Residues

PubMed Central

Morrow, John Kenneth; Zhang, Shuxing

2013-01-01

Most biological processes involve multiple proteins interacting with each other. It has been recently discovered that certain residues in these protein-protein interactions, which are called hot spots, contribute more significantly to binding affinity than others. Hot spot residues have unique and diverse energetic properties that make them challenging yet important targets in the modulation of protein-protein complexes. Design of therapeutic agents that interact with hot spot residues has proven to be a valid methodology in disrupting unwanted protein-protein interactions. Using biological methods to determine which residues are hot spots can be costly and time consuming. Recent advances in computational approaches to predict hot spots have incorporated a myriad of features, and have shown increasing predictive successes. Here we review the state of knowledge around protein-protein interactions, hot spots, and give an overview of multiple in silico prediction techniques of hot spot residues. PMID:22316154

Inhibition of turbulence in inertial-confinement-fusion hot spots by viscous dissipation.

PubMed

Weber, C R; Clark, D S; Cook, A W; Busby, L E; Robey, H F

2014-05-01

Achieving ignition in inertial confinement fusion (ICF) requires the formation of a high-temperature (>10 keV) central hot spot. Turbulence has been suggested as a mechanism for degrading the hot-spot conditions by altering transport properties, introducing colder, mixed material, or reducing the conversion of radially directed kinetic energy to hot-spot heating. We show, however, that the hot spot is very viscous, and the assumption of turbulent conditions in the hot spot is incorrect. This work presents the first high-resolution, three-dimensional simulations of National Ignition Facility (NIF) implosion experiments using detailed knowledge of implosion dynamics and instability seeds and including an accurate model of physical viscosity. We find that when viscous effects are neglected, the hot spot can exhibit a turbulent kinetic energy cascade. Viscous effects, however, are significant and strongly damp small-scale velocity structures, with a hot-spot Reynolds number in the range of only 10-100.

Inhibition of turbulence in inertial-confinement-fusion hot spots by viscous dissipation

NASA Astrophysics Data System (ADS)

Weber, C. R.; Clark, D. S.; Cook, A. W.; Busby, L. E.; Robey, H. F.

2014-05-01

Achieving ignition in inertial confinement fusion (ICF) requires the formation of a high-temperature (>10 keV) central hot spot. Turbulence has been suggested as a mechanism for degrading the hot-spot conditions by altering transport properties, introducing colder, mixed material, or reducing the conversion of radially directed kinetic energy to hot-spot heating. We show, however, that the hot spot is very viscous, and the assumption of turbulent conditions in the hot spot is incorrect. This work presents the first high-resolution, three-dimensional simulations of National Ignition Facility (NIF) implosion experiments using detailed knowledge of implosion dynamics and instability seeds and including an accurate model of physical viscosity. We find that when viscous effects are neglected, the hot spot can exhibit a turbulent kinetic energy cascade. Viscous effects, however, are significant and strongly damp small-scale velocity structures, with a hot-spot Reynolds number in the range of only 10--100.

Recombination or mutational hot spots in human mtDNA?

PubMed

Innan, Hideki; Nordborg, Magnus

2002-07-01

Awadalla, Eyre-Walker, and Maynard Smith (1999) recently argued that there might be recombination in human mitochondrial DNA (mtDNA). Their claim was based on their observation of decaying linkage disequilibrium (LD) as a function of physical distance. Their study was much criticized, and follow-up studies have failed to find any evidence for recombination. We argue that the criticisms levied, even if correct, could not possibly explain the findings of Awadalla, Eyre-Walker, and Maynard Smith (1999). Nonetheless, the test proposed by Awadalla, Eyre-Walker, and Maynard Smith (1999 ) is not robust because recombination is not the only explanation for decay of LD. We show that such a pattern can be caused by mutational hot spots as well. However, a closer look at the data suggests that the pattern observed was not caused by mutational hot spots but rather by chance. Thus, there appears to be no evidence for recombination in the mtDNA polymorphism data. In conclusion, we discuss the possibility of detecting recombination in mtDNA and the implications of its existence.

Image-guided brachytherapy for cervical cancer: analysis of D2 cc hot spot in three-dimensional and anatomic factors affecting D2 cc hot spot in organs at risk.

PubMed

Kim, Robert Y; Dragovic, Alek F; Whitley, Alexander C; Shen, Sui

2014-01-01

To analyze the D2 cc hot spot in three-dimensional CT and anatomic factors affecting the D2 cc hot spot in organs at risk (OARs). Thirty-one patients underwent pelvic CT scan after insertion of the applicator. High-dose-rate treatment planning was performed with standard loading patterns. The D2 cc structures in OARs were generated in three dimensional if the total equivalent dose in 2 Gy exceeded our defined dose limits (hot spot). The location of D2 cc hot spot was defined as the center of the largest D2 cc fragment. The relationship between the hot spot and the applicator position was reported in Digital Imaging and Communication in Medicine coordinates. The location of sigmoid, small bowel, and bladder D2 cc hot spots was around the endocervix: The mean location of sigmoid hot spot for lateral view was 1.6 cm posteriorly and 2.3 cm superiorly (Y, 1.6 and Z, 2.3), small bowel was 1.6 cm anteriorly and 2.7 cm superiorly (Y, -1.6 and Z, 2.7). The mean location of bladder hot spot was 1.6 cm anteriorly and 1.6 cm superiorly (Y, -1.6 and Z, 1.6). These hot spots were near the plane of Point A (X, 2.0 or -2.0; Y, 0; and Z, 2.0). The mean location of rectal hot spot was 1.6 cm posteriorly and 1.9 cm inferiorly (Y, 1.6 and Z, -1.9). D2 cc hot spot was affected by uterine wall thickness, uterine tandem position, fibroids, bladder fullness, bowel gas, and vaginal packing. Because of the location of the D2 cc hot spots, larger tumors present a challenge for adequate tumor coverage with a conventional brachytherapy applicator without an interstitial implant. Additionally, anatomic factors were identified which affect the D2 cc hot spot in OARs. Copyright © 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Criticality conditions of heterogeneous energetic materials under shock loading

NASA Astrophysics Data System (ADS)

Nassar, Anas; Rai, Nirmal Kumar; Sen, Oishik; Udaykumar, H. S.

2017-06-01

Shock interaction with the microstructural heterogeneities of energetic materials can lead to the formation of locally heated regions known as hot spots. These hot spots are the potential sites where chemical reaction may be initiated. However, the ability of a hot spot to initiate chemical reaction depends on its size, shape and strength (temperature). Previous study by Tarver et al. has shown that there exists a critical size and temperature for a given shape (spherical, cylindrical, and planar) of the hot spot above which reaction initiation is imminent. Tarver et al. assumed a constant temperature variation in the hot spot. However, the meso-scale simulations show that the temperature distribution within a hot spot formed from processes such as void collapse is seldom constant. Also, the shape of a hot spot can be arbitrary. This work is an attempt towards development of a critical hot spot curve which is a function of loading strength, duration and void morphology. To achieve the aforementioned goal, mesoscale simulations are conducted on porous HMX material. The process is repeated for different loading conditions and void sizes. The hot spots formed in the process are examined for criticality depending on whether they will ignite or not. The metamodel is used to obtain criticality curves and is compared with the critical hot spot curve of Tarver et al.

Bubble migration inside a liquid drop in a space laboratory

NASA Technical Reports Server (NTRS)

Annamalai, P.; Shankar, N.; Cole, R.; Subramanian, R. S.

1982-01-01

The design of experiments in materials processing for trials on board the Shuttle are described. Thermocapillary flows will be examined as an aid to mixing in the formation of glasses. Acoustically levitated molten glass spheres will be spot heated to induce surface flow away from the hot spot to induce mixing. The surface flows are also expected to cause internal convective motion which will drive entrained gas bubbles toward the hot spot, a process also enhanced by the presence of thermal gradients. The method is called fining, and will be augmented by rotation of the sphere to cause bubble migration toward the axes of rotation to form one large bubble which is more easily removed. Centering techniques to fix the maximum centering accuracy will also be tried. Ground-based studies of bubble migration in a rotating liquid and in a temperature gradient in a liquid drop are reviewed.

Topographic hot spot before descemet stripping automated endothelial keratoplasty is associated with postoperative hyperopic shift.

PubMed

Shimizu, Tsutomu; Yamaguchi, Takefumi; Satake, Yoshiyuki; Shimazaki, Jun

2015-03-01

The aim of this study was to investigate topographic "hot spots" on the anterior corneal surface before Descemet stripping automated endothelial keratoplasty (DSAEK) and their effects on postoperative visual acuity and hyperopic shift. Twenty-seven eyes of 27 patients with bullous keratopathy, who underwent DSAEK were studied. We defined a hot spot as a focal area with relatively high refractive power on the anterior corneal surface in eyes with bullous keratopathy. Refractive spherical equivalent, keratometric value, and corneal topography were retrospectively evaluated using anterior segment optical coherence tomography (AS-OCT). Hot spots were identified in 11 eyes (42.3%) before DSAEK and disappeared in 9 eyes of these eyes (81.8%) at 6 months after DSAEK. AS-OCT revealed focal epithelial thickening in the same areas as the hot spots. There was no significant difference in the postoperative visual acuity between eyes with and without hot spots (P > 0.05). The keratometric value of the anterior corneal surface significantly flattened from 45.7 ± 2.7 diopters (D) before DSAEK to 44.2 ± 2.7 D 1 month after DSAEK in eyes with hot spots (P = 0.01), whereas in eyes without hot spots, there were no significant differences in the keratometric values before and after DSAEK. At 6 months, the refractive change was +1.1 ± 1.3 D in eyes with hot spots and -0.2 ± 0.6 D in eyes without hot spots (P = 0.034). In eyes with focal epithelial thickening, topographic hot spots on the anterior corneal surface were observed using AS-OCT. The hot spots disappeared after DSAEK and had no influence on the postoperative visual acuity.

Hot spot mix in ICF implosions on the NIF

NASA Astrophysics Data System (ADS)

Ma, Tammy

2016-10-01

In the quest to achieve ignition through the inertial confinement fusion scheme, one of the critical challenges is to drive a symmetric implosion at high velocity without hydrodynamic instabilities becoming detrimental. These instabilities, primarily at the ablation front and the fuel-ablator interface, can cause mix of the higher-Z shell into the hot spot, resulting in increased radiation loss and thus reduced temperature and neutron yield. To quantify the level of mix, we developed a model that infers the level of hot spot contamination using the ratio of the enhanced x-ray production relative to the neutron yield. Applying this methodology to the full ensemble of indirect-drive National Ignition Facility (NIF) cryogenically layered DT implosions provides insight on the sensitivity of performance to the level of ablator-hot spot mix. In particular, the improvement seen with the High Foot design can be primarily attributed to a reduction in ablation-front instability mix that enabled the implosions to be pushed to higher velocity and performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, Lawrence Livermore National Security, LLC.

Solar 'hot spots' are still hot

NASA Technical Reports Server (NTRS)

Bai, Taeil

1990-01-01

Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

HotRegion: a database of predicted hot spot clusters.

PubMed

Cukuroglu, Engin; Gursoy, Attila; Keskin, Ozlem

2012-01-01

Hot spots are energetically important residues at protein interfaces and they are not randomly distributed across the interface but rather clustered. These clustered hot spots form hot regions. Hot regions are important for the stability of protein complexes, as well as providing specificity to binding sites. We propose a database called HotRegion, which provides the hot region information of the interfaces by using predicted hot spot residues, and structural properties of these interface residues such as pair potentials of interface residues, accessible surface area (ASA) and relative ASA values of interface residues of both monomer and complex forms of proteins. Also, the 3D visualization of the interface and interactions among hot spot residues are provided. HotRegion is accessible at http://prism.ccbb.ku.edu.tr/hotregion.

Dynamic programming-based hot spot identification approach for pedestrian crashes.

PubMed

Medury, Aditya; Grembek, Offer

2016-08-01

Network screening techniques are widely used by state agencies to identify locations with high collision concentration, also referred to as hot spots. However, most of the research in this regard has focused on identifying highway segments that are of concern to automobile collisions. In comparison, pedestrian hot spot detection has typically focused on analyzing pedestrian crashes in specific locations, such as at/near intersections, mid-blocks, and/or other crossings, as opposed to long stretches of roadway. In this context, the efficiency of the some of the widely used network screening methods has not been tested. Hence, in order to address this issue, a dynamic programming-based hot spot identification approach is proposed which provides efficient hot spot definitions for pedestrian crashes. The proposed approach is compared with the sliding window method and an intersection buffer-based approach. The results reveal that the dynamic programming method generates more hot spots with a higher number of crashes, while providing small hot spot segment lengths. In comparison, the sliding window method is shown to suffer from shortcomings due to a first-come-first-serve approach vis-à-vis hot spot identification and a fixed hot spot window length assumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatially Resolved Sub-millimeter Continuum Imaging of Neptune with ALMA

NASA Astrophysics Data System (ADS)

Iino, Takahiro; Yamada, Takayoshi

2018-02-01

This paper reports the result of spatially resolved 646 GHz sub-millimeter imaging observation of Neptune obtained by the Atacama Large Millimeter and sub-millimeter Array. The observation was performed in 2012 August as the flux calibration and synthesized beam size were small enough to resolve Neptune’s disk at this time. This analysis aims to constrain the vertical structure of deep and upper-tropospheric South polar hot spot detected previously with mid-IR, millimeter, and centimeter wavelength. The probed atmospheric pressure region estimated by the radiative-transfer method was between 1.0 and 0.6 bar for the nadir and South pole views, respectively. The South polar hot spot was not detected clearly with an uncertainty of 2.1 K. The apparent discontinuity of tropospheric and stratospheric hot spot may be caused by the vertical wind shear of South polar zonal jet.

Hot-spot investigations of utility scale panel configurations

NASA Technical Reports Server (NTRS)

Arnett, J. C.; Dally, R. B.; Rumburg, J. P.

1984-01-01

The causes of array faults and efforts to mitigate their effects are examined. Research is concentrated on the panel for the 900 kw second phase of the Sacramento Municipal Utility District (SMUD) project. The panel is designed for hot spot tolerance without comprising efficiency under normal operating conditions. Series/paralleling internal to each module improves tolerance in the power quadrant to cell short or open circuits. Analtyical methods are developed for predicting worst case shade patterns and calculating the resultant cell temperature. Experiments conducted on a prototype panel support the analytical calculations.

Impact Protection Assessment of the Redesigned Oregon Aero ZetaLiner Fitting System in the HGU-56/P Aircrew Integrated Helmet System

DTIC Science & Technology

2008-02-01

with atypical head anthropometry . A limited number of current users have anecdotally cited the TPL® as causing hot spots. Hot spots are defined as...6) is available in sizes: extra-extra-small (XXS), extra- small (XS), small(S), medium (M), large (L), and extra-large ( XL ). Each helmet is made up...head anthropometries than the small HGU-56/P. This is accomplished by 6 thickening the polystyrene energy-absorbing liners (EALs) in the XS and XXS

Identification of hot spot area of sediment contamination in a lake system using texture characteristics.

PubMed

Sheela, A M; Letha, J; Joseph, Sabu; Thomas, Jobin

2013-04-01

Texture plays an important role in the identification of polluted stretch in a lake system. The organic matter as well as toxic elements get accumulated in the finer sediments. The aim of the work is to show the spatio-temporal distribution of texture of the lake sediment (Akkulam-Veli lake, Kerala) and to identify the hot spot areas of contamination. Hot spot areas vary with seasons. During PRM, (premonsoon), the upstream portion of the Akkulam lake is the hot spot. During MON (monsoon), the downstream portion of the Akkulam lake and the upstream portion of the Veli lake are the hot spots. During POM (postmonsoon), hot spot area is the downstream portion of the Akkulam lake. This methodology can be used for the quick identification of hot spots in water bodies.

Computational identification of binding energy hot spots in protein-RNA complexes using an ensemble approach.

PubMed

Pan, Yuliang; Wang, Zixiang; Zhan, Weihua; Deng, Lei

2018-05-01

Identifying RNA-binding residues, especially energetically favored hot spots, can provide valuable clues for understanding the mechanisms and functional importance of protein-RNA interactions. Yet, limited availability of experimentally recognized energy hot spots in protein-RNA crystal structures leads to the difficulties in developing empirical identification approaches. Computational prediction of RNA-binding hot spot residues is still in its infant stage. Here, we describe a computational method, PrabHot (Prediction of protein-RNA binding hot spots), that can effectively detect hot spot residues on protein-RNA binding interfaces using an ensemble of conceptually different machine learning classifiers. Residue interaction network features and new solvent exposure characteristics are combined together and selected for classification with the Boruta algorithm. In particular, two new reference datasets (benchmark and independent) have been generated containing 107 hot spots from 47 known protein-RNA complex structures. In 10-fold cross-validation on the training dataset, PrabHot achieves promising performances with an AUC score of 0.86 and a sensitivity of 0.78, which are significantly better than that of the pioneer RNA-binding hot spot prediction method HotSPRing. We also demonstrate the capability of our proposed method on the independent test dataset and gain a competitive advantage as a result. The PrabHot webserver is freely available at http://denglab.org/PrabHot/. leideng@csu.edu.cn. Supplementary data are available at Bioinformatics online.

Applications and results of X-ray spectroscopy in implosion experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Epstein, R.; Regan, S. P.; Hammel, B. A.; Suter, L. J.; Scott, H. A.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Cerjan, C.; Collins, G. W.; Dixit, S. N.; Döppner, T.; Edwards, M. J.; Farley, D. R.; Fournier, K. B.; Glenn, S.; Glenzer, S. H.; Golovkin, I. E.; Hamza, A.; Hicks, D. G.; Izumi, N.; Jones, O. S.; Key, M. H.; Kilkenny, J. D.; Kline, J. L.; Kyrala, G. A.; Landen, O. L.; Ma, T.; MacFarlane, J. J.; Mackinnon, A. J.; Mancini, R. C.; McCrory, R. L.; Meyerhofer, D. D.; Meezan, N. B.; Nikroo, A.; Park, H.-S.; Patel, P. K.; Ralph, J. E.; Remington, B. A.; Sangster, T. C.; Smalyuk, V. A.; Springer, P. T.; Town, R. P. J.; Tucker, J. L.

2017-03-01

Current inertial confinement fusion experiments on the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] are attempting to demonstrate thermonuclear ignition using x-ray drive by imploding spherical targets containing hydrogen-isotope fuel in the form of a thin cryogenic layer surrounding a central volume of fuel vapor [J. Lindl, Phys. Plasmas 2, 3933 (1995)]. The fuel is contained within a plastic ablator layer with small concentrations of one or more mid-Z elements, e.g., Ge or Cu. The capsule implodes, driven by intense x-ray emission from the inner surface of a hohlraum enclosure irradiated by the NIF laser, and fusion reactions occur in the central hot spot near the time of peak compression. Ignition will occur if the hot spot within the compressed fuel layer attains a high-enough areal density to retain enough of the reaction product energy to reach nuclear reaction temperatures within the inertial hydrodynamic disassembly time of the fuel mass [J. Lindl, Phys. Plasmas 2, 3933 (1995)]. The primary purpose of the ablator dopants is to shield the ablator surface adjacent to the DT ice from heating by the hohlraum x-ray drive [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. Simulations predicted that these dopants would produce characteristic K-shell emission if ablator material mixed into the hot spot [B. A. Hammel et al., High Energy Density Phys. 6, 171 (2010)]. In NIF ignition experiments, emission and absorption features from these dopants appear in x-ray spectra measured with the hot-spot x-ray spectrometer in Supersnout II [S. P. Regan et al., "Hot-Spot X-Ray Spectrometer for the National Ignition Facility," to be submitted to Review of Scientific Instruments]. These include K-shell emission lines from the hot spot (driven primarily by inner-shell collisional ionization and dielectronic recombination) and photoionization edges, fluorescence, and absorption lines caused by the absorption of the hot-spot continuum in the shell. These features provide diagnostics of the central hot spot and the compressed shell, plus a measure of the shell mass that has mixed into the hot spot [S. P. Regan et al., Phys. Plasmas 19, 056307 (2012)] and evidence locating the origin of the mixed shell mass in the imploding ablator [S. P. Regan et al., Phys. Rev. Lett. 111, 045001 (2013)]. Spectra are analyzed and interpreted using detailed atomic models (including radiation-transport effects) to determine the characteristic temperatures, densities, and sizes of the emitting regions. A mix diagnostic based on enhanced continuum x-ray production, relative to neutron yield, provides sensitivity to the undoped shell material mixed into the hot spot [T. Ma et al., Phys. Rev. Lett., 111, 085004 (2013)]. Together, these mix-mass measurements confirm that mix is a serious impediment to ignition. The spectroscopy and atomic physics of shell dopants have become essential in confronting this impediment and will be described.

Hot spot detection, segmentation, and identification in PET images

NASA Astrophysics Data System (ADS)

Blaffert, Thomas; Meetz, Kirsten

2006-03-01

Positron Emission Tomography (PET) images provide functional or metabolic information from areas of high concentration of [18F]fluorodeoxyglucose (FDG) tracer, the "hot spots". These hot spots can be easily detected by the eye, but delineation and size determination required e.g. for diagnosis and staging of cancer is a tedious task that demands for automation. The approach for such an automated hot spot segmentation described in this paper comprises three steps: A region of interest detection by the watershed transform, a heart identification by an evaluation of scan lines, and the final segmentation of hot spot areas by a local threshold. The region of interest detection is the essential step, since it localizes the hot spot identification and the final segmentation. The heart identification is an example of how to differentiate between hot spots. Finally, we demonstrate the combination of PET and CT data. Our method is applicable to other techniques like SPECT.

Concentrator hot-spot testing, phase 1

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.

1987-01-01

Results of a study to determine the hot-spot susceptibility of concentrator cells, to provide a hot-spot qualification test for concentrator modules, and to provide guidelines for reducing hot-spot susceptibility are presented. Hot-spot heating occurs in a photovoltaic module when the short-circuit current of a cell is lower than the string operating current forcing the cell into reverse bias with a concurrent power dissipation. Although the basis for the concentrator module hot-spot qualification test is the test developed for flat-plate modules, issues, such as providing cell illumination, introduce additional complexities into the testing procedure. The same general guidelines apply for protecting concentrator modules from hot-spot stressing as apply to flat-plate modules. Therefore, recommendations are made on the number of bypass diodes required per given number of series cells per module or source circuit. In addition, a new method for determining the cell temperature in the laboratory or in the field is discussed.

Hot spots and active longitudes: Organization of solar activity as a probe of the interior

NASA Technical Reports Server (NTRS)

Bai, Taeil; Hoeksema, J. Todd; Scherrer, Phil H.

1995-01-01

In order to investigate how solar activity is organized in longitude, major solar flares, large sunspot groups, and large scale photospheric magnetic field strengths were analyzed. The results of these analyses are reported. The following results are discussed: hot spots, initially recognized as areas of high concentration of major flares, are the preferred locations for the emergence of big sunspot groups; double hot spots appear in pairs that rotate at the same rate separated by about 180 deg in longitude, whereas, single hot spots have no such companions; the northern and southern hemispheres behave differently in organizing solar activity in longitude; the lifetime of hot spots range from one to several solar cycles; a hot spot is not always active throughout its lifetime, but goes through dormant periods; and hot spots with different rotational periods coexist in the same hemisphere during the same solar cycle.

The evolutionary turnover of recombination hot spots contributes to speciation in mice.

PubMed

Smagulova, Fatima; Brick, Kevin; Pu, Yongmei; Camerini-Otero, R Daniel; Petukhova, Galina V

2016-02-01

Meiotic recombination is required for the segregation of homologous chromosomes and is essential for fertility. In most mammals, the DNA double-strand breaks (DSBs) that initiate meiotic recombination are directed to a subset of genomic loci (hot spots) by sequence-specific binding of the PRDM9 protein. Rapid evolution of the DNA-binding specificity of PRDM9 and gradual erosion of PRDM9-binding sites by gene conversion will alter the recombination landscape over time. To better understand the evolutionary turnover of recombination hot spots and its consequences, we mapped DSB hot spots in four major subspecies of Mus musculus with different Prdm9 alleles and in their F1 hybrids. We found that hot spot erosion governs the preferential usage of some Prdm9 alleles over others in hybrid mice and increases sequence diversity specifically at hot spots that become active in the hybrids. As crossovers are disfavored at such hot spots, we propose that sequence divergence generated by hot spot turnover may create an impediment for recombination in hybrids, potentially leading to reduced fertility and, eventually, speciation. Published by Cold Spring Harbor Laboratory Press.

The evolutionary turnover of recombination hot spots contributes to speciation in mice

PubMed Central

Smagulova, Fatima; Brick, Kevin; Pu, Yongmei; Camerini-Otero, R. Daniel; Petukhova, Galina V.

2016-01-01

Meiotic recombination is required for the segregation of homologous chromosomes and is essential for fertility. In most mammals, the DNA double-strand breaks (DSBs) that initiate meiotic recombination are directed to a subset of genomic loci (hot spots) by sequence-specific binding of the PRDM9 protein. Rapid evolution of the DNA-binding specificity of PRDM9 and gradual erosion of PRDM9-binding sites by gene conversion will alter the recombination landscape over time. To better understand the evolutionary turnover of recombination hot spots and its consequences, we mapped DSB hot spots in four major subspecies of Mus musculus with different Prdm9 alleles and in their F1 hybrids. We found that hot spot erosion governs the preferential usage of some Prdm9 alleles over others in hybrid mice and increases sequence diversity specifically at hot spots that become active in the hybrids. As crossovers are disfavored at such hot spots, we propose that sequence divergence generated by hot spot turnover may create an impediment for recombination in hybrids, potentially leading to reduced fertility and, eventually, speciation. PMID:26833728

High-temperature hot spots on Io as seen by the Galileo solid state imaging (SSI) experiment

USGS Publications Warehouse

McEwen, A.S.; Simonelli, D.P.; Senske, D.R.; Klaasen, K.P.; Keszthelyi, L.; Johnson, T.V.; Geissler, P.E.; Carr, M.H.; Belton, M.J.S.

1997-01-01

High-temperature hot spots on Io have been imaged at ???50 km spatial resolution by Galileo's CCD imaging system (SSI). Images were acquired during eclipses (Io in Jupiter's shadow) via the SSI clear filter (???0.4-1.0 ??m), detecting emissions from both small intense hot spots and diffuse extended glows associated with Io's atmosphere and plumes. A total of 13 hot spots have been detected over ???70% of Io's surface. Each hot spot falls precisely on a low-albedo feature corresponding to a caldera floor and/or lava flow. The hot-spot temperatures must exceed ???700 K for detection by SSI. Observations at wavelengths longer than those available to SSI require that most of these hot spots actually have significantly higher temperatures (???1000 K or higher) and cover small areas. The high-temperature hot spots probably mark the locations of active silicate volcanism, supporting suggestions that the eruption and near-surface movement of silicate magma drives the heat flow and volcanic activity of Io. Copyright 1997 by the American Geophysical Union.

Hot Spot and Whole-Tumor Enumeration of CD8+ Tumor-Infiltrating Lymphocytes Utilizing Digital Image Analysis Is Prognostic in Triple-Negative Breast Cancer.

PubMed

McIntire, Patrick J; Irshaid, Lina; Liu, Yifang; Chen, Zhengming; Menken, Faith; Nowak, Eugene; Shin, Sandra J; Ginter, Paula S

2018-05-07

CD8 + tumor-infiltrating lymphocytes (TILs) have emerged as a prognostic indicator in triple-negative breast cancer (TNBC). There is debate surrounding the prognostic value of hot spots for CD8 + TIL enumeration. We compared hot spot versus whole-tumor CD8 + TIL enumeration in prognosticating TNBC using immunohistochemistry on whole tissue sections and quantification by digital image analysis (Halo imaging analysis software; Indica Labs, Corrales, NM). A wide range of clinically relevant hot spot sizes was evaluated. CD8 + TIL enumeration was independently statistically significant for all hot spot sizes and whole-tumor annotations for disease-free survival by multivariate analysis. A 10× objective (2.2 mm diameter) hot spot was found to correlate significantly with overall survival (P = .04), while the remaining hot spots and whole-tumor CD8 + TIL enumeration did not (P > .05). Statistical significance was not demonstrated when comparing between hot spots and whole-tumor annotations, as the groups had overlapping confidence intervals. CD8 + TIL hot spot enumeration is equivalent to whole-tumor enumeration for prognostication in TNBC and may serve as a good alternative methodology in future studies and clinical practice. Copyright © 2018 Elsevier Inc. All rights reserved.

Wetted foam liquid fuel ICF target experiments

DOE PAGES

Olson, R. E.; Leeper, R. J.; Yi, S. A.; ...

2016-05-26

We are developing a new NIF experimental platform that employs wetted foam liquid fuel layer ICF capsules. We will use the liquid fuel layer capsules in a NIF sub-scale experimental campaign to explore the relationship between hot spot convergence ratio (CR) and the predictability of hot spot formation. DT liquid layer ICF capsules allow for flexibility in hot spot CR via the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density. Our hypothesis is that the predictive capability of hot spot formation is robust and 1D-like for a relatively low CR hot spot (CR~15), but will becomemore » less reliable as hot spot CR is increased to CR>20. Simulations indicate that backing off on hot spot CR is an excellent way to reduce capsule instability growth and to improve robustness to low-mode x-ray flux asymmetries. In the initial experiments, we will test our hypothesis by measuring hot spot size, neutron yield, ion temperature, and burn width to infer hot spot pressure and compare to predictions for implosions with hot spot CR's in the range of 12 to 25. Larger scale experiments are also being designed, and we will advance from sub-scale to full-scale NIF experiments to determine if 1D-like behavior at low CR is retained as the scale-size is increased. The long-term objective is to develop a liquid fuel layer ICF capsule platform with robust thermonuclear burn, modest CR, and significant α-heating with burn propagation.« less

An approach for addressing hard-to-detect hot spots.

PubMed

Abelquist, Eric W; King, David A; Miller, Laurence F; Viars, James A

2013-05-01

The Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) survey approach is comprised of systematic random sampling coupled with radiation scanning to assess acceptability of potential hot spots. Hot spot identification for some radionuclides may not be possible due to the very weak gamma or x-ray radiation they emit-these hard-to-detect nuclides are unlikely to be identified by field scans. Similarly, scanning technology is not yet available for chemical contamination. For both hard-to-detect nuclides and chemical contamination, hot spots are only identified via volumetric sampling. The remedial investigation and cleanup of sites under the Comprehensive Environmental Response, Compensation, and Liability Act typically includes the collection of samples over relatively large exposure units, and concentration limits are applied assuming the contamination is more or less uniformly distributed. However, data collected from contaminated sites demonstrate contamination is often highly localized. These highly localized areas, or hot spots, will only be identified if sample densities are high or if the environmental characterization program happens to sample directly from the hot spot footprint. This paper describes a Bayesian approach for addressing hard-to-detect nuclides and chemical hot spots. The approach begins using available data (e.g., as collected using the standard approach) to predict the probability that an unacceptable hot spot is present somewhere in the exposure unit. This Bayesian approach may even be coupled with the graded sampling approach to optimize hot spot characterization. Once the investigator concludes that the presence of hot spots is likely, then the surveyor should use the data quality objectives process to generate an appropriate sample campaign that optimizes the identification of risk-relevant hot spots.

Hot Spots of Recombination in Fission Yeast: Inactivation of the M26 Hot Spot by Deletion of the Ade6 Promoter and the Novel Hotspot Ura4-Aim

PubMed Central

Zahn-Zabal, M.; Lehmann, E.; Kohli, J.

1995-01-01

The M26 mutation in the ade6 gene of Schizosaccharomyces pombe creates a hot spot of meiotic recombination. A single base substitution, the M26 mutation is situated within the open reading frame, near the 5' end. It has previously been shown that the heptanucleotide sequence 5' ATGACGT 3', which includes the M26 mutation, is required for hot spot activity. The 510-bp ade6-delXB deletion encompasses the promoter and the first 23 bp of the open reading frame, ending 112 bp upstream of M26. Deletion of the promoter in cis to M26 abolishes hot spot activity, while deletion in trans to M26 has no effect. Homozygous deletion of the promoter also eliminates M26 hot spot activity, indicating that the heterology created through deletion of the promoter per se is not responsible for the loss of hot spot activity. Thus, DNA sequences other than the heptanucleotide 5' ATGACGT 3', which must be located at the 5' end of the ade6 gene, appear to be required for hot spot activity. While the M26 hotspot stimulates crossovers associated with M26 conversion, it does not affect the crossover frequency in the intervals adjacent to ade6. The flanking marker ura4-aim, a heterology created by insertion of the ura4(+) gene upstream of ade6, turned out to be a hot spot itself. It shows disparity of conversion with preferential loss of the insertion. The frequency of conversion at ura4-aim is reduced when the M26 hot spot is active 15 kb away, indicating competition for recombination factors by hot spots in close proximity. PMID:7498729

Correlates of county-level nonviral sexually transmitted infection hot spots in the US: application of hot spot analysis and spatial logistic regression.

PubMed

Chang, Brian A; Pearson, William S; Owusu-Edusei, Kwame

2017-04-01

We used a combination of hot spot analysis (HSA) and spatial regression to examine county-level hot spot correlates for the most commonly reported nonviral sexually transmitted infections (STIs) in the 48 contiguous states in the United States (US). We obtained reported county-level total case rates of chlamydia, gonorrhea, and primary and secondary (P&S) syphilis in all counties in the 48 contiguous states from national surveillance data and computed temporally smoothed rates using 2008-2012 data. Covariates were obtained from county-level multiyear (2008-2012) American Community Surveys from the US census. We conducted HSA to identify hot spot counties for all three STIs. We then applied spatial logistic regression with the spatial error model to determine the association between the identified hot spots and the covariates. HSA indicated that ≥84% of hot spots for each STI were in the South. Spatial regression results indicated that, a 10-unit increase in the percentage of Black non-Hispanics was associated with ≈42% (P < 0.01) [≈22% (P < 0.01), for Hispanics] increase in the odds of being a hot spot county for chlamydia and gonorrhea, and ≈27% (P < 0.01) [≈11% (P < 0.01) for Hispanics] for P&S syphilis. Compared with the other regions (West, Midwest, and Northeast), counties in the South were 6.5 (P < 0.01; chlamydia), 9.6 (P < 0.01; gonorrhea), and 4.7 (P < 0.01; P&S syphilis) times more likely to be hot spots. Our study provides important information on hot spot clusters of nonviral STIs in the entire United States, including associations between hot spot counties and sociodemographic factors. Published by Elsevier Inc.

A Computational Investigation of Small-Molecule Engagement of Hot Spots at Protein-Protein Interaction Interfaces.

PubMed

Xu, David; Si, Yubing; Meroueh, Samy O

2017-09-25

The binding affinity of a protein-protein interaction is concentrated at amino acids known as hot spots. It has been suggested that small molecules disrupt protein-protein interactions by either (i) engaging receptor protein hot spots or (ii) mimicking hot spots of the protein ligand. Yet, no systematic studies have been done to explore how effectively existing small-molecule protein-protein interaction inhibitors mimic or engage hot spots at protein interfaces. Here, we employ explicit-solvent molecular dynamics simulations and end-point MM-GBSA free energy calculations to explore this question. We select 36 compounds for which high-quality binding affinity and cocrystal structures are available. Five complexes that belong to three classes of protein-protein interactions (primary, secondary, and tertiary) were considered, namely, BRD4•H4, XIAP•Smac, MDM2•p53, Bcl-xL•Bak, and IL-2•IL-2Rα. Computational alanine scanning using MM-GBSA identified hot-spot residues at the interface of these protein interactions. Decomposition energies compared the interaction of small molecules with individual receptor hot spots to those of the native protein ligand. Pharmacophore analysis was used to investigate how effectively small molecules mimic the position of hot spots of the protein ligand. Finally, we study whether small molecules mimic the effects of the native protein ligand on the receptor dynamics. Our results show that, in general, existing small-molecule inhibitors of protein-protein interactions do not optimally mimic protein-ligand hot spots, nor do they effectively engage protein receptor hot spots. The more effective use of hot spots in future drug design efforts may result in smaller compounds with higher ligand efficiencies that may lead to greater success in clinical trials.

Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

NASA Technical Reports Server (NTRS)

Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

2013-01-01

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 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, 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 150-200 m/s, much faster than the 100 m/s 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.

The crime prevention value of hot spots policing.

PubMed

Braga, Anthony A

2006-08-01

This paper reviews the available research evidence on the effectiveness of hot spots policing programs in reducing crime and disorder. The research identified five randomized controlled experiments and four non-equivalent control group quasi-experiments evaluating the effects of hot spots policing interventions on crime. Seven of nine selected evaluations reported noteworthy crime and disorder reductions. Meta-analyses of the randomized experiments revealed statistically significant mean effect sizes favoring hot spots policing interventions in reducing citizen calls for service in treatment places relative to control places. When immediate spatial displacement was measured, it was very limited and unintended crime prevention benefits were associated with the hot spots policing programs. The results of this review suggest that hot spots policing is an effective crime prevention strategy.

Digital image analysis of Ki67 in hot spots is superior to both manual Ki67 and mitotic counts in breast cancer.

PubMed

Stålhammar, Gustav; Robertson, Stephanie; Wedlund, Lena; Lippert, Michael; Rantalainen, Mattias; Bergh, Jonas; Hartman, Johan

2018-05-01

During pathological examination of breast tumours, proliferative activity is routinely evaluated by a count of mitoses. Adding immunohistochemical stains of Ki67 provides extra prognostic and predictive information. However, the currently used methods for these evaluations suffer from imperfect reproducibility. It is still unclear whether analysis of Ki67 should be performed in hot spots, in the tumour periphery, or as an average of the whole tumour section. The aim of this study was to compare the clinical relevance of mitoses, Ki67 and phosphohistone H3 in two cohorts of primary breast cancer specimens (total n = 294). Both manual and digital image analysis scores were evaluated for sensitivity and specificity for luminal B versus A subtype as defined by PAM50 gene expression assays, for high versus low transcriptomic grade, for axillary lymph node status, and for prognostic value in terms of prediction of overall and relapse-free survival. Digital image analysis of Ki67 outperformed the other markers, especially in hot spots. Tumours with high Ki67 expression and high numbers of phosphohistone H3-positive cells had significantly increased hazard ratios for all-cause mortality within 10 years from diagnosis. Replacing manual mitotic counts with digital image analysis of Ki67 in hot spots increased the differences in overall survival between the highest and lowest histological grades, and added significant prognostic information. Digital image analysis of Ki67 in hot spots is the marker of choice for routine analysis of proliferation in breast cancer. © 2017 John Wiley & Sons Ltd.

Effects on Ridge Segmentation, Magmatic Plumbing and Eruption Style Caused by Weak Hot-spot to Ridge Interaction: the Central Indian Ridge and Rodrigues Hot-spot Couplet.

NASA Astrophysics Data System (ADS)

Murton, B. J.; Parson, L. M.; Sauter, D.

2001-12-01

The intermediate spreading, Central Indian Ridge (CIR) forms a couplet with a weak hot-spot of which the Rodrigues archipelago is an expression. Recently collected bathymetry shows that despite having little in the way of a significant topographic swell, the hot-spot is associated with a change in offset sense across adjacent transforms of the CIR causing the ridge to draw nearer to the Rodrigues island system. The most proximal ridge segment of the CIR is over 20km long and comprises three non-transform bounded sub-segments. The most northerly sub-segment has a shallow (<3000m), narrow (<5km) and featureless flat rift valley. TOBI sidescan sonar imagery shows that the segment is host to a 15km-long, 5km-wide single sheet flow. Elsewhere in the segment the valley floor is characterised by long (>5km), narrow (<1km) ridges that often terminate in conical seamounts. These ridges are the loci of some of the acoustically freshest volcanic facies in the rift valley. Samples recovered from these ridges have similar petrology along strike. With increasing distance south along the CIR, the ridge segments are typically 500m deeper than to the north. Here they are about 75km long and bounded by transform offsets that are 50 km long. However, even in the deepest parts of these segments, where the axial floor is over 4000m deep at the ridge-transform-intersections, there is fresh lava and other evidence for abundant volcanic activity. Within these segments, the rift valley comprises mainly seamounts and hummocky volcanic features. We believe the westward stepping trend of the CIR towards the Rodrigues islands is a function of the hot spot. The elevated temperature and volatile content to the west reduces mantle viscosity which, combined with thinner and hence weaker lithosphere, influencec the loci of initial oceanic rifting and the relative position of the ridge axis. The unusually great length of the northern segment has a similar origin with the presence of thin and weak lithosphere and less viscous mantle reducing the tectonic ``memory" of the ridge system. Despite being farther from the hot-spot, the southern segments have a similarly robust melt supply to the northern segment. The main difference is melt delivery, with the northern segments supplied via long dikes that also erupt as fissure ridges, while to the south the supply is more disseminated. The massive lava sheet and robust and narrow axial valley in the northernmost sub-segment coincides with the tip of a southward propagating system. This system appears to herald the onset of more productive melting a may represent a relocation of the hot-spot-ridge interaction.

Climate impacts on global hot spots of marine biodiversity.

PubMed

Ramírez, Francisco; Afán, Isabel; Davis, Lloyd S; Chiaradia, André

2017-02-01

Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming. In particular, these marine biodiversity hot spots have undergone local to regional increasing water temperatures, slowing current circulation, and decreasing primary productivity. Furthermore, when we overlapped these hot spots with available industrial fishery data, albeit coarser than our estimates of climate impacts, they suggest a worrying coincidence whereby the world's richest areas for marine biodiversity are also those areas mostly affected by both climate change and industrial fishing. In light of these findings, we offer an adaptable framework for determining local to regional areas of special concern for the conservation of marine biodiversity. This has exposed the need for finer-scaled fishery data to assist in the management of global fisheries if the accumulative, but potentially preventable, effect of fishing on climate change impacts is to be minimized within areas prioritized for marine biodiversity conservation.

Accurate prediction of hot spot residues through physicochemical characteristics of amino acid sequences.

PubMed

Chen, Peng; Li, Jinyan; Wong, Limsoon; Kuwahara, Hiroyuki; Huang, Jianhua Z; Gao, Xin

2013-08-01

Hot spot residues of proteins are fundamental interface residues that help proteins perform their functions. Detecting hot spots by experimental methods is costly and time-consuming. Sequential and structural information has been widely used in the computational prediction of hot spots. However, structural information is not always available. In this article, we investigated the problem of identifying hot spots using only physicochemical characteristics extracted from amino acid sequences. We first extracted 132 relatively independent physicochemical features from a set of the 544 properties in AAindex1, an amino acid index database. Each feature was utilized to train a classification model with a novel encoding schema for hot spot prediction by the IBk algorithm, an extension of the K-nearest neighbor algorithm. The combinations of the individual classifiers were explored and the classifiers that appeared frequently in the top performing combinations were selected. The hot spot predictor was built based on an ensemble of these classifiers and to work in a voting manner. Experimental results demonstrated that our method effectively exploited the feature space and allowed flexible weights of features for different queries. On the commonly used hot spot benchmark sets, our method significantly outperformed other machine learning algorithms and state-of-the-art hot spot predictors. The program is available at http://sfb.kaust.edu.sa/pages/software.aspx. Copyright © 2013 Wiley Periodicals, Inc.

75 FR 29537 - Draft Transportation Conformity Guidance for Quantitative Hot-spot Analyses in PM2.5

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-26

... Quantitative Hot- spot Analyses in PM 2.5 and PM 10 Nonattainment and Maintenance Areas AGENCY: Environmental... finalized, this guidance would help state and local agencies complete quantitative PM 2.5 and PM 10 hot-spot...), EPA stated that quantitative PM 2.5 and PM 10 hot-spot analyses would not be required until EPA...

Density-based kinetics for mesoscale simulations of detonation initiation in energetic materials

NASA Astrophysics Data System (ADS)

Jackson, Thomas Luther; Zhang, Ju

2017-07-01

In this work we present one- and two-dimensional mesoscale simulations of detonation initiation in energetic materials. We solve the reactive Euler equations, with the energy equation augmented by a power deposition term. The reaction rate at the mesoscale is modelled using a density-based kinetics scheme, adapted from standard 'Ignition and Growth' models. The deposition term is based on previous results of simulations of void collapse at the microscale, modelled at the mesoscale as hot spots. For an isolated hot spot in a homogeneous medium, it is found that a critical size of the hot spots exists. If the hot spots exceed the critical size, initiation of detonation can be achieved. For sub-critical hot-spot sizes, we show that it takes a collection of hot spots to achieve detonation. We also carry out two-dimensional mesoscale simulations of random packs of HMX crystals in a binder, and show that the transition between no detonation and detonation depends on the number density of the hot spots, the initial radius of the hot spot, the post-shock pressure of an imposed shock, and the amplitude of the power deposition term.

Hot-spot qualification testing of concentrator modules

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.; Sugimura, R. S.; Ross, R. G., Jr.

1987-01-01

Results of a study to determine the hot-spot susceptibility of concentrator cells, to provide a hot-spot qualification test for concentrator modules, and to provide guidelines for reducing hot-spot susceptibility are presented. Hot-spot heating occurs in a photovoltaic module when the short-circuit current of a cell is lower than the string operating current, forcing the cell into reverse bias with a concurrent power dissipation. Although the basis for the concentrator-module hot-spot qualification test is the test developed for flat-plate modules, issues such as providing cell illumination introduce additional complexities into the testing procedure. The results indicate that the same general guidelines apply to protecting concentrator modules from hot-spot stressing as apply to flat-plate modules, and recommendations are made on the number of bypass diodes required per given number of series cells per module or source circuit. A method for determining the cell temperature in the laboratory or in the field is discussed.

Three-dimensional simulations of void collapse in energetic materials

NASA Astrophysics Data System (ADS)

Rai, Nirmal Kumar; Udaykumar, H. S.

2018-03-01

The collapse of voids in porous energetic materials leads to hot-spot formation and reaction initiation. This work advances the current knowledge of the dynamics of void collapse and hot-spot formation using 3D reactive void collapse simulations in HMX. Four different void shapes, i.e., sphere, cylinder, plate, and ellipsoid, are studied. For all four shapes, collapse generates complex three-dimensional (3D) baroclinic vortical structures. The hot spots are collocated with regions of intense vorticity. The differences in the vortical structures for the different void shapes are shown to significantly impact the relative sensitivity of the voids. Voids of high surface area generate hot spots of greater intensity; intricate, highly contorted vortical structures lead to hot spots of corresponding tortuosity and therefore enhanced growth rates of reaction fronts. In addition, all 3D voids are shown to be more sensitive than their two-dimensional (2D) counterparts. The results provide physical insights into hot-spot formation and growth and point to the limitations of 2D analyses of hot-spot formation.

Hot Spots on Io: Initial Results From Galileo's Near Infrared Mapping Spectrometer

NASA Technical Reports Server (NTRS)

Lopes-Gautier, Rosaly; Davies, A. G.; Carlson, R.; Smythe, W.; Kamp, L.; Soderblom, L.; Leader, F. E.; Mehlman, R.

1997-01-01

The Near-Infrared Mapping Spectrometer on Galileo has monitored the volcanic activity on Io since June 28, 1996. This paper presents preliminary analysis of NIMS thermal data for the first four orbits of the Galileo mission. NIMS has detected 18 new hot spots and 12 others which were previously known to be active. The distribution of the hot spots on Io's surface may not be random, as hot spots surround the two bright, SO2-rich regions of Bosphorus Regio and Colchis Regio. Most hot spots scan to be persistently active from orbit to orbit and 10 of those detected were active in 1979 during the Voyager encounters. We report the distribution of hot spot temperatures and find that they are consistent with silicate volcanism.

Photovoltaic module hot spot durability design and test methods

NASA Technical Reports Server (NTRS)

Arnett, J. C.; Gonzalez, C. C.

1981-01-01

As part of the Jet Propulsion Laboratory's Low-Cost Solar Array Project, the susceptibility of fat-plate modules to hot-spot problems is investigated. Hot-spot problems arise in modules when the cells become back-biased and operate in the negative-voltage quadrant, as a result of short-circuit current mismatch, cell cracking or shadowing. The details of a qualification test for determining the capability of modules of surviving field hot-spot problems and typical results of this test are presented. In addition, recommended circuit-design techniques for improving the module and array reliability with respect to hot-spot problems are presented.

Hot spot and trench volcano separations

NASA Technical Reports Server (NTRS)

Lingenfelter, R. E.; Schubert, G.

1974-01-01

It is suggested that the distribution of separations between trench volcanos located along subduction zones reflects the depth of partial melting, and that the separation distribution for hot spot volcanoes near spreading centers provides a measure of the depth of mantle convection cells. It is further proposed that the lateral dimensions of mantle convection cells are also represented by the hot-spot separations (rather than by ridge-trench distances) and that a break in the distribution of hot spot separations at 3000 km is evidence for both whole mantle convection and a deep thermal plume origin of hot spots.

40 CFR 93.116 - Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots).

Code of Federal Regulations, 2012 CFR

2012-07-01

..., PM10, and PM2.5 violations (hot-spots). 93.116 Section 93.116 Protection of Environment ENVIRONMENTAL....116 Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots). (a) This paragraph... hot-spot analysis in PM10 and PM2.5 nonattainment and maintenance areas for FHWA/FTA projects that are...

40 CFR 93.116 - Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots).

Code of Federal Regulations, 2013 CFR

2013-07-01

..., PM10, and PM2.5 violations (hot-spots). 93.116 Section 93.116 Protection of Environment ENVIRONMENTAL....116 Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots). (a) This paragraph... hot-spot analysis in PM10 and PM2.5 nonattainment and maintenance areas for FHWA/FTA projects that are...

40 CFR 93.116 - Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots).

Code of Federal Regulations, 2014 CFR

2014-07-01

..., PM10, and PM2.5 violations (hot-spots). 93.116 Section 93.116 Protection of Environment ENVIRONMENTAL....116 Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots). (a) This paragraph... hot-spot analysis in PM10 and PM2.5 nonattainment and maintenance areas for FHWA/FTA projects that are...

40 CFR 93.116 - Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots).

Code of Federal Regulations, 2011 CFR

2011-07-01

..., PM10, and PM2.5 violations (hot-spots). 93.116 Section 93.116 Protection of Environment ENVIRONMENTAL....116 Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots). (a) This paragraph... hot-spot analysis in PM10 and PM2.5 nonattainment and maintenance areas for FHWA/FTA projects that are...

40 CFR 93.116 - Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots).

Code of Federal Regulations, 2010 CFR

2010-07-01

..., PM10, and PM2.5 violations (hot-spots). 93.116 Section 93.116 Protection of Environment ENVIRONMENTAL....116 Criteria and procedures: Localized CO, PM10, and PM2.5 violations (hot-spots). (a) This paragraph... hot-spot analysis in PM10 and PM2.5 nonattainment and maintenance areas for FHWA/FTA projects that are...

DBAC: A simple prediction method for protein binding hot spots based on burial levels and deeply buried atomic contacts

PubMed Central

2011-01-01

Background A protein binding hot spot is a cluster of residues in the interface that are energetically important for the binding of the protein with its interaction partner. Identifying protein binding hot spots can give useful information to protein engineering and drug design, and can also deepen our understanding of protein-protein interaction. These residues are usually buried inside the interface with very low solvent accessible surface area (SASA). Thus SASA is widely used as an outstanding feature in hot spot prediction by many computational methods. However, SASA is not capable of distinguishing slightly buried residues, of which most are non hot spots, and deeply buried ones that are usually inside a hot spot. Results We propose a new descriptor called “burial level” for characterizing residues, atoms and atomic contacts. Specifically, burial level captures the depth the residues are buried. We identify different kinds of deeply buried atomic contacts (DBAC) at different burial levels that are directly broken in alanine substitution. We use their numbers as input for SVM to classify between hot spot or non hot spot residues. We achieve F measure of 0.6237 under the leave-one-out cross-validation on a data set containing 258 mutations. This performance is better than other computational methods. Conclusions Our results show that hot spot residues tend to be deeply buried in the interface, not just having a low SASA value. This indicates that a high burial level is not only a necessary but also a more sufficient condition than a low SASA for a residue to be a hot spot residue. We find that those deeply buried atoms become increasingly more important when their burial levels rise up. This work also confirms the contribution of deeply buried interfacial atomic contacts to the energy of protein binding hot spot. PMID:21689480

Advantages of Fast Ignition Scenarios with Two Hot Spots for Space Propulsion Systems

NASA Astrophysics Data System (ADS)

Shmatov, M. L.

The use of the fast ignition scenarios with the attempts to create two hot spots in one blob of the compressed thermonuclear fuel or, briefly, scenarios with two hot spots in space propulsion systems is proposed. The model, predicting that for such scenarios the probability pf of failure of ignition of thermonuclear microexplosion can be significantly less than that for the similar scenarios with the attempts to create one hot spot in one blob of the compressed fuel, is presented. For space propulsion systems consuming a relatively large amount of propellant, a decrease in pf due to the choice of the scenario with two hot spots can result in large, for example, two-fold, increase in the payload mass. Other advantages of the scenarios with two hot spots and some problems related to them are considered.

Hot spots on Io: Initial results from Galileo's near infrared mapping spectrometer

USGS Publications Warehouse

Lopes-Gautier, R.; Davies, A.G.; Carlson, R.; Smythe, W.; Kamp, L.; Soderblom, L.; Leader, F.E.; Mehlman, R.

1997-01-01

The Near-Infrared Mapping Spectrometer on Galileo has monitored the volcanic activity on Io since June 28, 1996. This paper presents preliminary analysis of NIMS thermal data for the first four orbits of the Galileo mission. NIMS has detected 18 new hot spots and 12 others which were previously known to be active. The distribution of the hot spots on Io's surface may not be random, as hot spots surround the two bright, SO2-rich regions of Bosphorus Regio and Colchis Regio. Most hot spots seem to be persistently active from orbit to orbit and 10 of those detected were active in 1979 during the Voyager encounters. We report the distribution of hot spot temperatures and find that they are consistent with silicate volcanism. Copyright 1997 by the American Geophysical Union.

Analysis of microstructure-dependent shock dissipation and hot-spot formation in granular metalized explosive

NASA Astrophysics Data System (ADS)

Chakravarthy, Sunada; Gonthier, Keith A.

2016-07-01

Variations in the microstructure of granular explosives (i.e., particle packing density, size, shape, and composition) can affect their shock sensitivity by altering thermomechanical fields at the particle-scale during pore collapse within shocks. If the deformation rate is fast, hot-spots can form, ignite, and interact, resulting in burn at the macro-scale. In this study, a two-dimensional finite and discrete element technique is used to simulate and examine shock-induced dissipation and hot-spot formation within low density explosives (68%-84% theoretical maximum density (TMD)) consisting of large ensembles of HMX (C4H8N8O8) and aluminum (Al) particles (size ˜ 60 -360 μm). Emphasis is placed on identifying how the inclusion of Al influences effective shock dissipation and hot-spot fields relative to equivalent ensembles of neat/pure HMX for shocks that are sufficiently strong to eliminate porosity. Spatially distributed hot-spot fields are characterized by their number density and area fraction enabling their dynamics to be described in terms of nucleation, growth, and agglomeration-dominated phases with increasing shock strength. For fixed shock particle speed, predictions indicate that decreasing packing density enhances shock dissipation and hot-spot formation, and that the inclusion of Al increases dissipation relative to neat HMX by pressure enhanced compaction resulting in fewer but larger HMX hot-spots. Ensembles having bimodal particle sizes are shown to significantly affect hot-spot dynamics by altering the spatial distribution of hot-spots behind shocks.

A feature-based approach to modeling protein-protein interaction hot spots.

PubMed

Cho, Kyu-il; Kim, Dongsup; Lee, Doheon

2009-05-01

Identifying features that effectively represent the energetic contribution of an individual interface residue to the interactions between proteins remains problematic. Here, we present several new features and show that they are more effective than conventional features. By combining the proposed features with conventional features, we develop a predictive model for interaction hot spots. Initially, 54 multifaceted features, composed of different levels of information including structure, sequence and molecular interaction information, are quantified. Then, to identify the best subset of features for predicting hot spots, feature selection is performed using a decision tree. Based on the selected features, a predictive model for hot spots is created using support vector machine (SVM) and tested on an independent test set. Our model shows better overall predictive accuracy than previous methods such as the alanine scanning methods Robetta and FOLDEF, and the knowledge-based method KFC. Subsequent analysis yields several findings about hot spots. As expected, hot spots have a larger relative surface area burial and are more hydrophobic than other residues. Unexpectedly, however, residue conservation displays a rather complicated tendency depending on the types of protein complexes, indicating that this feature is not good for identifying hot spots. Of the selected features, the weighted atomic packing density, relative surface area burial and weighted hydrophobicity are the top 3, with the weighted atomic packing density proving to be the most effective feature for predicting hot spots. Notably, we find that hot spots are closely related to pi-related interactions, especially pi . . . pi interactions.

Understanding the effects of laser imprint on plastic-target implosions on OMEGA

DOE PAGES

Hu, S. X.; Michel, D. T.; Davis, A. K.; ...

2016-10-03

Understanding the effects of laser imprint on target performance is critical to the success of direct-drive inertial confinement fusion. Directly measuring the disruption caused by laser imprints to the imploding shell and hot-spot formation, in comparison with multidimensional radiation–hydrodynamic simulations, can provide a clear picture of how laser nonuniformities cause target performance to degrade. With the recently developed x-ray self-emission imaging technique and the state-of-the-art physics models recently implemented in the two-dimensional hydrocode DRACO, a systematic study of laser-imprint effects on warm target implosions on OMEGA has been performed using both experimental results and simulations. By varying the laser-picket intensity,more » the imploding shells were set at different adiabats (from α = 2 to α = 6). As the shell adiabats decreased, it was observed that (1) the measured shell thickness at the time the hot spot lit up became larger than the uniform one-dimensional (1-D) predictions; (2) the hot-spot core emitted earlier than the corresponding 1-D predictions; (3) the measured neutron yield first increased then decreased as the shell adiabat α was reduced; and (4) the hot-spot size reduced as α decreased for cases where SSD (smoothing by spectral dispersion) was on but became larger for low-α shots in cases where SSD was off. Most of these experimental observations are well reproduced by DRACO simulations with laser imprints including modes up to λ max = 200. In addition, these studies identify the importance of laser imprint as the major source of degrading target performance for OMEGA implosions of adiabat α ≤ 3. Mitigating laser imprints is required to improve low-α target performance.« less

Understanding the effects of laser imprint on plastic-target implosions on OMEGA

NASA Astrophysics Data System (ADS)

Hu, S. X.; Michel, D. T.; Davis, A. K.; Betti, R.; Radha, P. B.; Campbell, E. M.; Froula, D. H.; Stoeckl, C.

2016-10-01

Understanding the effects of laser imprint on target performance is critical to the success of direct-drive inertial confinement fusion. Directly measuring the disruption caused by laser imprints to the imploding shell and hot-spot formation, in comparison with multidimensional radiation-hydrodynamic simulations, can provide a clear picture of how laser nonuniformities cause target performance to degrade. With the recently developed x-ray self-emission imaging technique and the state-of-the-art physics models recently implemented in the two-dimensional hydrocode DRACO, a systematic study of laser-imprint effects on warm target implosions on OMEGA has been performed using both experimental results and simulations. By varying the laser-picket intensity, the imploding shells were set at different adiabats (from α = 2 to α = 6). As the shell adiabats decreased, it was observed that (1) the measured shell thickness at the time the hot spot lit up became larger than the uniform one-dimensional (1-D) predictions; (2) the hot-spot core emitted earlier than the corresponding 1-D predictions; (3) the measured neutron yield first increased then decreased as the shell adiabat α was reduced; and (4) the hot-spot size reduced as α decreased for cases where SSD (smoothing by spectral dispersion) was on but became larger for low-α shots in cases where SSD was off. Most of these experimental observations are well reproduced by DRACO simulations with laser imprints including modes up to λmax = 200. These studies identify the importance of laser imprint as the major source of degrading target performance for OMEGA implosions of adiabat α ≤ 3. Mitigating laser imprints is required to improve low-α target performance.

Understanding the effects of laser imprint on plastic-target implosions on OMEGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, S. X.; Michel, D. T.; Davis, A. K.

Understanding the effects of laser imprint on target performance is critical to the success of direct-drive inertial confinement fusion. Directly measuring the disruption caused by laser imprints to the imploding shell and hot-spot formation, in comparison with multidimensional radiation–hydrodynamic simulations, can provide a clear picture of how laser nonuniformities cause target performance to degrade. With the recently developed x-ray self-emission imaging technique and the state-of-the-art physics models recently implemented in the two-dimensional hydrocode DRACO, a systematic study of laser-imprint effects on warm target implosions on OMEGA has been performed using both experimental results and simulations. By varying the laser-picket intensity,more » the imploding shells were set at different adiabats (from α = 2 to α = 6). As the shell adiabats decreased, it was observed that (1) the measured shell thickness at the time the hot spot lit up became larger than the uniform one-dimensional (1-D) predictions; (2) the hot-spot core emitted earlier than the corresponding 1-D predictions; (3) the measured neutron yield first increased then decreased as the shell adiabat α was reduced; and (4) the hot-spot size reduced as α decreased for cases where SSD (smoothing by spectral dispersion) was on but became larger for low-α shots in cases where SSD was off. Most of these experimental observations are well reproduced by DRACO simulations with laser imprints including modes up to λ max = 200. In addition, these studies identify the importance of laser imprint as the major source of degrading target performance for OMEGA implosions of adiabat α ≤ 3. Mitigating laser imprints is required to improve low-α target performance.« less

VLBI observations of 23 hot spots in the starburst galaxy M82

NASA Technical Reports Server (NTRS)

Bartel, Norbert; Ratner, Michael I.; Shapiro, Irwin I.; Rogers, Alan E. E.; Preston, Robert A.

1987-01-01

The simultaneous 2.3 and 8.4 GHz VLBI observations of 23 hot spots in the nuclear region of M82 presented indicate the presence of six hot spots at 2.3 GHz, but only one at 8.4 GHz. Attention is given to a mapping of the brightest hot spot, 41.9+58, at 2.3 GHz, which exhibits a complex brightness distribution whose angular width in the NE-SW direction is 45 mas at the 10-percent contour. These data are consistent with the hot spots in M82 being powerful SNRs, with ages between about 10 and 300 yr.

Radiotherapy Dose Perturbation of Esophageal Stents Examined in an Experimental Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atwood, Todd F.; Hsu, Annie; Ogara, Maydeen M.

2012-04-01

Purpose: To investigate the radiotherapy dose perturbations caused by esophageal stents in patients undergoing external beam treatments for esophageal cancer. Methods and Materials: Four esophageal stents were examined (three metallic stents: WallFlex, Ultraflex, and Alveolus; one nonmetallic stent with limited radiopaque markers for visualization: Polyflex). All experiments were performed in a liquid water phantom with a custom acrylic stent holder. Radiochromic film was used to measure the dose distributions adjacent to the stents at locations proximal and distal to the radiation source. The stents were placed in an air-filled cavity to simulate the esophagus. Treatment plans were created and deliveredmore » for photon energies of 6 and 15 MV, and data analysis was performed on uniform regions of interest, according to the size and geometric placement of the films, to quantify the dose perturbations. Results: The three metallic stents produced the largest dose perturbations with distinct patterns of 'hot' spots (increased dose) measured proximal to the radiation source (up to 15.4%) and both 'cold' (decreased dose) and hot spots measured distal to the radiation source (range, -6.1%-5.8%). The polymeric Polyflex stent produced similar dose perturbations when the radiopaque markers were examined (range, -7.6%-15.4%). However, when the radiopaque markers were excluded from the analysis, the Polyflex stent produced significantly smaller dose perturbations, with maximum hot spots of 7.3% and cold spots of -3.2%. Conclusions: The dose perturbations caused by esophageal stents during the treatment of esophageal cancer using external beam radiotherapy should be understood. These perturbations will result in hot and cold spots in the esophageal mucosa, with varying magnitudes depending on the stent. The nonmetallic Polyflex stent appears to be the most suitable for patients undergoing radiotherapy, but further studies are necessary to determine the clinical significance of the dose perturbations.« less

Radiotherapy dose perturbation of esophageal stents examined in an experimental model.

PubMed

Atwood, Todd F; Hsu, Annie; Ogara, Maydeen M; Luba, Daniel G; Tamler, Bradley J; Disario, James A; Maxim, Peter G

2012-04-01

To investigate the radiotherapy dose perturbations caused by esophageal stents in patients undergoing external beam treatments for esophageal cancer. Four esophageal stents were examined (three metallic stents: WallFlex, Ultraflex, and Alveolus; one nonmetallic stent with limited radiopaque markers for visualization: Polyflex). All experiments were performed in a liquid water phantom with a custom acrylic stent holder. Radiochromic film was used to measure the dose distributions adjacent to the stents at locations proximal and distal to the radiation source. The stents were placed in an air-filled cavity to simulate the esophagus. Treatment plans were created and delivered for photon energies of 6 and 15 MV, and data analysis was performed on uniform regions of interest, according to the size and geometric placement of the films, to quantify the dose perturbations. The three metallic stents produced the largest dose perturbations with distinct patterns of "hot" spots (increased dose) measured proximal to the radiation source (up to 15.4%) and both "cold" (decreased dose) and hot spots measured distal to the radiation source (range, -6.1%-5.8%). The polymeric Polyflex stent produced similar dose perturbations when the radiopaque markers were examined (range, -7.6%-15.4%). However, when the radiopaque markers were excluded from the analysis, the Polyflex stent produced significantly smaller dose perturbations, with maximum hot spots of 7.3% and cold spots of -3.2%. The dose perturbations caused by esophageal stents during the treatment of esophageal cancer using external beam radiotherapy should be understood. These perturbations will result in hot and cold spots in the esophageal mucosa, with varying magnitudes depending on the stent. The nonmetallic Polyflex stent appears to be the most suitable for patients undergoing radiotherapy, but further studies are necessary to determine the clinical significance of the dose perturbations. Copyright © 2012 Elsevier Inc. All rights reserved.

An automated decision-tree approach to predicting protein interaction hot spots.

PubMed

Darnell, Steven J; Page, David; Mitchell, Julie C

2007-09-01

Protein-protein interactions can be altered by mutating one or more "hot spots," the subset of residues that account for most of the interface's binding free energy. The identification of hot spots requires a significant experimental effort, highlighting the practical value of hot spot predictions. We present two knowledge-based models that improve the ability to predict hot spots: K-FADE uses shape specificity features calculated by the Fast Atomic Density Evaluation (FADE) program, and K-CON uses biochemical contact features. The combined K-FADE/CON (KFC) model displays better overall predictive accuracy than computational alanine scanning (Robetta-Ala). In addition, because these methods predict different subsets of known hot spots, a large and significant increase in accuracy is achieved by combining KFC and Robetta-Ala. The KFC analysis is applied to the calmodulin (CaM)/smooth muscle myosin light chain kinase (smMLCK) interface, and to the bone morphogenetic protein-2 (BMP-2)/BMP receptor-type I (BMPR-IA) interface. The results indicate a strong correlation between KFC hot spot predictions and mutations that significantly reduce the binding affinity of the interface. 2007 Wiley-Liss, Inc.

Detection of spatial hot spots and variation for the neon flying squid Ommastrephes bartramii resources in the northwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Feng, Yongjiu; Chen, Xinjun; Liu, Yan

2017-07-01

With the increasing effects of global climate change and fishing activities, the spatial distribution of the neon flying squid ( Ommastrephes bartramii) is changing in the traditional fishing ground of 150°-160°E and 38°-45°N in the northwest Pacific Ocean. This research aims to identify the spatial hot and cold spots (i.e. spatial clusters) of O. bartramii to reveal its spatial structure using commercial fishery data from 2007 to 2010 collected by Chinese mainland squid-jigging fleets. A relatively strongly-clustered distribution for O. bartramii was observed using an exploratory spatial data analysis (ESDA) method. The results show two hot spots and one cold spot in 2007 while only one hot and one cold spots were identified each year from 2008 to 2010. The hot and cold spots in 2007 occupied 8.2% and 5.6% of the study area, respectively; these percentages for hot and cold spot areas were 5.8% and 3.1% in 2008, 10.2% and 2.9% in 2009, and 16.4% and 11.9% in 2010, respectively. Nearly half (>45%) of the squid from 2007 to 2009 reported by Chinese fleets were caught in hot spot areas while this percentage reached its peak at 68.8% in 2010, indicating that the hot spot areas are central fishing grounds. A further change analysis shows the area centered at 156°E/43.5°N was persistent as a hot spot over the whole period from 2007 to 2010. Furthermore, the hot spots were mainly identified in areas with sea surface temperature (SST) in the range of 15-20°C around warm Kuroshio Currents as well as with the chlorophyll- a (chl- a) concentration above 0.3 mg/m3. The outcome of this research improves our understanding of spatiotemporal hotspots and its variation for O. bartramii and is useful for sustainable exploitation, assessment, and management of this squid.

Computational Characterization of Impact Induced Multi-Scale Dissipation in Reactive Solid Composites

DTIC Science & Technology

2016-07-01

Predicted variation in (a) hot-spot number density , (b) hot-spot volume fraction, and (c) hot-spot specific surface area for each ensemble with piston speed...packing density , characterized by its effective solid volume fraction φs,0, affects hot-spot statistics for pressure dominated waves corresponding to...distribution in solid volume fraction within each ensemble was nearly Gaussian, and its standard deviation decreased with increasing density . Analysis of

Bounds on geologically current rates of motion of groups of hot spots

NASA Astrophysics Data System (ADS)

Wang, Chengzu; Gordon, Richard G.; Zhang, Tuo

2017-06-01

It is widely believed that groups of hot spots in different regions of the world are in relative motion at rates of 10 to 30 mm a-1 or more. Here we present a new method for analyzing geologically current motion between groups of hot spots beneath different plates. In an inversion of 56 globally distributed, equally weighted trends of hot spot tracks, the dispersion is dominated by differences in trend between different plates rather than differences within plates. Nonetheless the rate of hot spot motion perpendicular to the direction of absolute plate motion, vperp, differs significantly from zero for only 3 of 10 plates and then by merely 0.3 to 1.4 mm a-1. The global mean upper bound on |vperp| is 3.2 ± 2.7 mm a-1. Therefore, hot spots move slowly and can be used to define a global reference frame for plate motions.

Live-Cell Pyrophosphate Imaging by in Situ Hot-Spot Generation.

PubMed

Li, Mingmin; Li, Jin; Di, Huixia; Liu, Huiqiao; Liu, Dingbin

2017-03-21

Controlling the electromagnetic hot-spot generation is essential for surface-enhanced Raman scattering (SERS) assays. Current hot-spot-based SERS assays have been extensively studied in solutions or on substrates. However, probing biospecies by controlling the hot-spot assembly in living systems has not been demonstrated thus far. Herein, we report a background-free SERS probe for imaging pyrophosphate (PPi), a biochemically significant anion, in living cells. Intracellular PPi is able to induce the nanoparticle dimerization, thus creating an intense electromagnetic hot spot and dramatically enhancing the signal of the Raman reporters residing in the hot spot. More impressively, the reporter we used in this study provides a strong and sharp single peak in the cellular Raman-silent region (1800-2800 cm -1 ), thus eliminating the possible background interference. This strategy could be readily extended to detect other biomarkers by only replacing the recognition ligands.

KFC Server: interactive forecasting of protein interaction hot spots.

PubMed

Darnell, Steven J; LeGault, Laura; Mitchell, Julie C

2008-07-01

The KFC Server is a web-based implementation of the KFC (Knowledge-based FADE and Contacts) model-a machine learning approach for the prediction of binding hot spots, or the subset of residues that account for most of a protein interface's; binding free energy. The server facilitates the automated analysis of a user submitted protein-protein or protein-DNA interface and the visualization of its hot spot predictions. For each residue in the interface, the KFC Server characterizes its local structural environment, compares that environment to the environments of experimentally determined hot spots and predicts if the interface residue is a hot spot. After the computational analysis, the user can visualize the results using an interactive job viewer able to quickly highlight predicted hot spots and surrounding structural features within the protein structure. The KFC Server is accessible at http://kfc.mitchell-lab.org.

KFC Server: interactive forecasting of protein interaction hot spots

PubMed Central

Darnell, Steven J.; LeGault, Laura; Mitchell, Julie C.

2008-01-01

The KFC Server is a web-based implementation of the KFC (Knowledge-based FADE and Contacts) model—a machine learning approach for the prediction of binding hot spots, or the subset of residues that account for most of a protein interface's; binding free energy. The server facilitates the automated analysis of a user submitted protein–protein or protein–DNA interface and the visualization of its hot spot predictions. For each residue in the interface, the KFC Server characterizes its local structural environment, compares that environment to the environments of experimentally determined hot spots and predicts if the interface residue is a hot spot. After the computational analysis, the user can visualize the results using an interactive job viewer able to quickly highlight predicted hot spots and surrounding structural features within the protein structure. The KFC Server is accessible at http://kfc.mitchell-lab.org. PMID:18539611

Numerical Modeling of the Sensitivity of X-Ray Driven Implosions to Low-Mode Flux Asymmetries

DOE PAGES

Scott, R. H. H.; Clark, D. S.; Bradley, D. K.; ...

2013-02-01

In this study, the sensitivity of inertial confinement fusion implosions of the type performed on the National Ignition Facility (NIF) [1] to low-mode flux asymmetries has been investigated numerically. It is shown that large-amplitude, low-order mode shapes (Legendre polynomial P4), resulting from associated low order flux asymmetries, cause spatial variations in capsule and fuel momentum that prevent the DT “ice” layer from being decelerated uniformly by the hot spot pressure. This reduces the transfer of kinetic to internal energy of the central hot spot, thus reducing neutron yield. Furthermore, synthetic gated x-ray images indicate that the P4 component of hotmore » spot self-emission shape is insensitive to P4 hot spot shapes, and a positive P4 asymmetry aliases itself as a negative or oblate P2 in these images. Correction of this apparent P2 distortion can further distort the implosion while creating a round x-ray image. Long wavelength asymmetries may be playing a significant role in the observed yield reduction of NIF DT implosions relative to detailed post-shot 2D simulations.« less

New tuning method of the low-mode asymmetry for ignition capsule implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Jianfa, E-mail: gu-jianfa@iapcm.ac.cn; Dai, Zhensheng; Zou, Shiyang

2015-12-15

In the deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility, the hot spot and the surrounding main fuel layer show obvious P2 asymmetries. This may be caused by the large positive P2 radiation flux asymmetry during the peak pulse resulting form the poor propagation of the inner laser beam in the gas-filled hohlraum. The symmetry evolution of ignition capsule implosions is investigated by applying P2 radiation flux asymmetries during different time intervals. A series of two-dimensional simulation results show that a positive P2 flux asymmetry during the peak pulse results in a positive P2 shell ρR asymmetry;more » while an early time positive P2 flux asymmetry causes a negative P2 in the fuel ρR shape. The opposite evolution behavior of shell ρR asymmetry is used to develop a new tuning method to correct the radiation flux asymmetry during the peak pulse by adding a compensating same-phased P2 drive asymmetry during the early time. The significant improvements of the shell ρR symmetry, hot spot shape, hot spot internal energy, and neutron yield indicate that the tuning method is quite effective. The similar tuning method can also be used to control the early time drive asymmetries.« less

Phenotyping at hot spots and tagging of QTLs conferring spot blotch resistance in bread wheat.

PubMed

Singh, Virender; Singh, Gyanendra; Chaudhury, A; Ojha, Ashish; Tyagi, B S; Chowdhary, A K; Sheoran, Sonia

2016-11-01

Spot blotch is a major foliar disease of wheat caused by Bipolaris sorokiniana in warm and humid environments of the world including South Asian countries. In India, it has a larger impact in Indo-Gangetic plains of the country. Therefore, the present study was undertaken to phenotype a mapping population at different hot spots of India and to detect quantitative trait loci (QTL) for resistance to spot blotch in wheat. For this study, 209 single seed descent (SSD) derived F 8 , F 9 , F 10 recombinant inbred lines (RILs) of the cross 'Sonalika' (an Indian susceptible cultivar)/'BH 1146' (a Brazilian resistant cultivar) were assessed for spot blotch resistance at two hot spot locations (Coochbehar and Kalyani) for three years and for two years under controlled conditions in the polyhouse (Karnal). The population showed large variation in spot blotch reaction for disease severity in all the environments indicating polygenic nature of the disease. Microsatellite markers were used to create the linkage maps. Joint and/or individual year analysis by composite interval mapping (CIM) and likelihood of odds ratio (LOD) >2.1, detected two consistent QTLs mapped on chromosome 7BL and 7DL and these explained phenotypic variation of 11.4 percent and 9.5 percent over the years and locations, respectively. The resistance at these loci was contributed by the parent 'BH 1146' and shown to be independent of plant height and earliness. Besides, association of some agro-morphological traits has also been observed with percent disease severity. These identified genomic regions may be used in future wheat breeding programs through marker assisted selection for developing spot blotch resistant cultivars.

Smart SERS Hot Spots: Single Molecules Can Be Positioned in a Plasmonic Nanojunction Using Host-Guest Chemistry.

PubMed

Kim, Nam Hoon; Hwang, Wooseup; Baek, Kangkyun; Rohman, Md Rumum; Kim, Jeehong; Kim, Hyun Woo; Mun, Jungho; Lee, So Young; Yun, Gyeongwon; Murray, James; Ha, Ji Won; Rho, Junsuk; Moskovits, Martin; Kim, Kimoon

2018-04-04

Single-molecule surface-enhanced Raman spectroscopy (SERS) offers new opportunities for exploring the complex chemical and biological processes that cannot be easily probed using ensemble techniques. However, the ability to place the single molecule of interest reliably within a hot spot, to enable its analysis at the single-molecule level, remains challenging. Here we describe a novel strategy for locating and securing a single target analyte in a SERS hot spot at a plasmonic nanojunction. The "smart" hot spot was generated by employing a thiol-functionalized cucurbit[6]uril (CB[6]) as a molecular spacer linking a silver nanoparticle to a metal substrate. This approach also permits one to study molecules chemically reluctant to enter the hot spot, by conjugating them to a moiety, such as spermine, that has a high affinity for CB[6]. The hot spot can accommodate at most a few, and often only a single, analyte molecule. Bianalyte experiments revealed that one can reproducibly treat the SERS substrate such that 96% of the hot spots contain a single analyte molecule. Furthermore, by utilizing a series of molecules each consisting of spermine bound to perylene bisimide, a bright SERS molecule, with polymethylene linkers of varying lengths, the SERS intensity as a function of distance from the center of the hot spot could be measured. The SERS enhancement was found to decrease as 1 over the square of the distance from the center of the hot spot, and the single-molecule SERS cross sections were found to increase with AgNP diameter.

A feature-based approach to modeling protein–protein interaction hot spots

PubMed Central

Cho, Kyu-il; Kim, Dongsup; Lee, Doheon

2009-01-01

Identifying features that effectively represent the energetic contribution of an individual interface residue to the interactions between proteins remains problematic. Here, we present several new features and show that they are more effective than conventional features. By combining the proposed features with conventional features, we develop a predictive model for interaction hot spots. Initially, 54 multifaceted features, composed of different levels of information including structure, sequence and molecular interaction information, are quantified. Then, to identify the best subset of features for predicting hot spots, feature selection is performed using a decision tree. Based on the selected features, a predictive model for hot spots is created using support vector machine (SVM) and tested on an independent test set. Our model shows better overall predictive accuracy than previous methods such as the alanine scanning methods Robetta and FOLDEF, and the knowledge-based method KFC. Subsequent analysis yields several findings about hot spots. As expected, hot spots have a larger relative surface area burial and are more hydrophobic than other residues. Unexpectedly, however, residue conservation displays a rather complicated tendency depending on the types of protein complexes, indicating that this feature is not good for identifying hot spots. Of the selected features, the weighted atomic packing density, relative surface area burial and weighted hydrophobicity are the top 3, with the weighted atomic packing density proving to be the most effective feature for predicting hot spots. Notably, we find that hot spots are closely related to π–related interactions, especially π · · · π interactions. PMID:19273533

Hot-spot durability testing of amorphous cells and modules

NASA Technical Reports Server (NTRS)

Gonzalez, Charles; Jetter, Elizabeth

1985-01-01

This paper discusses the results of a study to determine the hot-spot susceptibility of amorphous-silicon (a-Si) cells and modules, and to provide guidelines for reducing that susceptibility. Amorphous-Si cells are shown to have hot-spot susceptibility levels similar to crystalline-silicon (C-Si) cells. This premise leads to the fact that the same general guidelines must apply to protecting a-Si cells from hot-spot stressing that apply to C-Si cells. Recommendations are made on ways of reducing a-Si module hot-spot susceptibility including the traditional method of using bypass diodes and a new method unique to thin-film cells, limiting the string current by limiting cell area.

Hot-spot mix in ignition-scale inertial confinement fusion targets.

PubMed

Regan, S P; Epstein, R; Hammel, B A; Suter, L J; Scott, H A; Barrios, M A; Bradley, D K; Callahan, D A; Cerjan, C; Collins, G W; Dixit, S N; Döppner, T; Edwards, M J; Farley, D R; Fournier, K B; Glenn, S; Glenzer, S H; Golovkin, I E; Haan, S W; Hamza, A; Hicks, D G; Izumi, N; Jones, O S; Kilkenny, J D; Kline, J L; Kyrala, G A; Landen, O L; Ma, T; MacFarlane, J J; MacKinnon, A J; Mancini, R C; McCrory, R L; Meezan, N B; Meyerhofer, D D; Nikroo, A; Park, H-S; Ralph, J; Remington, B A; Sangster, T C; Smalyuk, V A; Springer, P T; Town, R P J

2013-07-26

Mixing of plastic ablator material, doped with Cu and Ge dopants, deep into the hot spot of ignition-scale inertial confinement fusion implosions by hydrodynamic instabilities is diagnosed with x-ray spectroscopy on the National Ignition Facility. The amount of hot-spot mix mass is determined from the absolute brightness of the emergent Cu and Ge K-shell emission. The Cu and Ge dopants placed at different radial locations in the plastic ablator show the ablation-front hydrodynamic instability is primarily responsible for hot-spot mix. Low neutron yields and hot-spot mix mass between 34(-13,+50)  ng and 4000(-2970,+17 160)  ng are observed.

Hot-spot mix in ignition-scale inertial confinement fusion targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Regan, S. P.; Epstein, R.; Hammel, B. A.

Mixing of plastic ablator material, doped with Cu and Ge dopants, deep into the hot spot of ignition-scale inertial confinement fusion implosions by hydrodynamic instabilities is diagnosed with x-ray spectroscopy on the National Ignition Facility. The amount of hot-spot mix mass is determined from the absolute brightness of the emergent Cu and Ge K-shell emission. The Cu and Ge dopants placed at different radial locations in the plastic ablator show the ablation-front hydrodynamic instability is primarily responsible for hot-spot mix. As a result, low neutron yields and hot-spot mix mass between 34(–13,+50) ng and 4000(–2970,+17 160) ng are observed.

Hot-spot mix in ignition-scale inertial confinement fusion targets

DOE PAGES

Regan, S. P.; Epstein, R.; Hammel, B. A.; ...

2013-07-22

Mixing of plastic ablator material, doped with Cu and Ge dopants, deep into the hot spot of ignition-scale inertial confinement fusion implosions by hydrodynamic instabilities is diagnosed with x-ray spectroscopy on the National Ignition Facility. The amount of hot-spot mix mass is determined from the absolute brightness of the emergent Cu and Ge K-shell emission. The Cu and Ge dopants placed at different radial locations in the plastic ablator show the ablation-front hydrodynamic instability is primarily responsible for hot-spot mix. As a result, low neutron yields and hot-spot mix mass between 34(–13,+50) ng and 4000(–2970,+17 160) ng are observed.

DNA methylation epigenetically silences crossover hot spots and controls chromosomal domains of meiotic recombination in Arabidopsis.

PubMed

Yelina, Nataliya E; Lambing, Christophe; Hardcastle, Thomas J; Zhao, Xiaohui; Santos, Bruno; Henderson, Ian R

2015-10-15

During meiosis, homologous chromosomes undergo crossover recombination, which is typically concentrated in narrow hot spots that are controlled by genetic and epigenetic information. Arabidopsis chromosomes are highly DNA methylated in the repetitive centromeres, which are also crossover-suppressed. Here we demonstrate that RNA-directed DNA methylation is sufficient to locally silence Arabidopsis euchromatic crossover hot spots and is associated with increased nucleosome density and H3K9me2. However, loss of CG DNA methylation maintenance in met1 triggers epigenetic crossover remodeling at the chromosome scale, with pericentromeric decreases and euchromatic increases in recombination. We used recombination mutants that alter interfering and noninterfering crossover repair pathways (fancm and zip4) to demonstrate that remodeling primarily involves redistribution of interfering crossovers. Using whole-genome bisulfite sequencing, we show that crossover remodeling is driven by loss of CG methylation within the centromeric regions. Using cytogenetics, we profiled meiotic DNA double-strand break (DSB) foci in met1 and found them unchanged relative to wild type. We propose that met1 chromosome structure is altered, causing centromere-proximal DSBs to be inhibited from maturation into interfering crossovers. These data demonstrate that DNA methylation is sufficient to silence crossover hot spots and plays a key role in establishing domains of meiotic recombination along chromosomes. © 2015 Yelina et al.; Published by Cold Spring Harbor Laboratory Press.

Climate impacts on global hot spots of marine biodiversity

PubMed Central

Ramírez, Francisco; Afán, Isabel; Davis, Lloyd S.; Chiaradia, André

2017-01-01

Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming. In particular, these marine biodiversity hot spots have undergone local to regional increasing water temperatures, slowing current circulation, and decreasing primary productivity. Furthermore, when we overlapped these hot spots with available industrial fishery data, albeit coarser than our estimates of climate impacts, they suggest a worrying coincidence whereby the world’s richest areas for marine biodiversity are also those areas mostly affected by both climate change and industrial fishing. In light of these findings, we offer an adaptable framework for determining local to regional areas of special concern for the conservation of marine biodiversity. This has exposed the need for finer-scaled fishery data to assist in the management of global fisheries if the accumulative, but potentially preventable, effect of fishing on climate change impacts is to be minimized within areas prioritized for marine biodiversity conservation. PMID:28261659

Hot spot generation in energetic materials created by long-wavelength infrared radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ming-Wei; You, Sizhu; Suslick, Kenneth S.

Hot spots produced by long-wavelength infrared (LWIR) radiation in an energetic material, crystalline RDX (1,3,5-trinitroperhydro-1,3,5-triazine), were studied by thermal-imaging microscopy. The LWIR source was a CO{sub 2} laser operating in the 28-30 THz range. Hot spot generation was studied using relatively low intensity (∼100 W cm{sup −2}), long-duration (450 ms) LWIR pulses. The hot spots could be produced repeatedly in individual RDX crystals, to investigate the fundamental mechanisms of hot spot generation by LWIR, since the peak hot-spot temperatures were kept to ∼30 K above ambient. Hot spots were generated preferentially beneath RDX crystal planes making oblique angles with the LWIR beam. Surprisingly,more » hot spots were more prominent when the LWIR wavelength was tuned to be weakly absorbed (absorption depth ∼30 μm) than when the LWIR wavelength was strongly absorbed (absorption depth ∼5 μm). This unexpected effect was explained using a model that accounts for LWIR refraction and RDX thermal conduction. The weakly absorbed LWIR is slightly focused underneath the oblique crystal planes, and it penetrates the RDX crystals more deeply, increasing the likelihood of irradiating RDX defect inclusions that are able to strongly absorb or internally focus the LWIR beam.« less

Distinct Rayleigh scattering from hot spot mutant p53 proteins reveals cancer cells.

PubMed

Jun, Ho Joon; Nguyen, Anh H; Kim, Yeul Hong; Park, Kyong Hwa; Kim, Doyoun; Kim, Kyeong Kyu; Sim, Sang Jun

2014-07-23

The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Causes of hot-spot wetland loss in the Mississippi delta plain

USGS Publications Warehouse

Morton, R.A.; Tiling, G.; Ferina, N.F.

2003-01-01

Field surveys and sediment cores were used to estimate marsh erosion and land subsidence at Madison Bay, a well-known wetland loss hot spot in coastal Louisiana. Former marshes of Madison Bay are under about 1 m of water. Nearly two-thirds of the permanent flooding was caused by rapid subsidence in the late 1960s, whereas the other third was caused by subsequent erosion. Subsidence rates near Madison Bay since the 1960s (???20 mm/yr) are an order of magnitude greater than deltaic subsidence rates averaged for the past 400-4000 yr (???2 mm/yr). The rapid acceleration and unexpected decline in wetland losses in the Mississippi delta plain are difficult to explain on the basis of most physical and biogeochemical processes. There are, however, close temporal and spatial correlations among regional wetland loss, high subsidence rates, and large-volume fluid production from nearby hydrocarbon fields. The decreased rates of wetland loss since the 1970s may be related to decreased rates of subsidence caused by significantly decreased rates of subsurface fluid withdrawal. Annual fluid production from the Lapeyrouse, Lirette, and Bay Baptiste fields that encompass Madison Bay accelerated in the 1960s, peaked about 1970, and then declined abruptly. Large decreases in pore pressure in the Lapeyrouse field have likely altered subsurface stresses and reactivated a major fault that coincides with the wetland loss hot spot. Therefore, wetland losses at Madison Bay can be closely linked to rapid subsidence and possible fault reactivation induced by long-term, large-volume hydrocarbon production. ?? 2003. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Vortices Bump into a Hot Spot in Jupiter Atmosphere

NASA Image and Video Library

2013-03-14

In this series of images from NASA Cassini spacecraft, a dark, rectangular hot spot interacts with a line of vortices that approaches from on the upper-right side. The interaction distorts the shape of the hot spot, leaving it diminished.

Integrating water exclusion theory into βcontacts to predict binding free energy changes and binding hot spots

PubMed Central

2014-01-01

Background Binding free energy and binding hot spots at protein-protein interfaces are two important research areas for understanding protein interactions. Computational methods have been developed previously for accurate prediction of binding free energy change upon mutation for interfacial residues. However, a large number of interrupted and unimportant atomic contacts are used in the training phase which caused accuracy loss. Results This work proposes a new method, βACV ASA , to predict the change of binding free energy after alanine mutations. βACV ASA integrates accessible surface area (ASA) and our newly defined β contacts together into an atomic contact vector (ACV). A β contact between two atoms is a direct contact without being interrupted by any other atom between them. A β contact’s potential contribution to protein binding is also supposed to be inversely proportional to its ASA to follow the water exclusion hypothesis of binding hot spots. Tested on a dataset of 396 alanine mutations, our method is found to be superior in classification performance to many other methods, including Robetta, FoldX, HotPOINT, an ACV method of β contacts without ASA integration, and ACV ASA methods (similar to βACV ASA but based on distance-cutoff contacts). Based on our data analysis and results, we can draw conclusions that: (i) our method is powerful in the prediction of binding free energy change after alanine mutation; (ii) β contacts are better than distance-cutoff contacts for modeling the well-organized protein-binding interfaces; (iii) β contacts usually are only a small fraction number of the distance-based contacts; and (iv) water exclusion is a necessary condition for a residue to become a binding hot spot. Conclusions βACV ASA is designed using the advantages of both β contacts and water exclusion. It is an excellent tool to predict binding free energy changes and binding hot spots after alanine mutation. PMID:24568581

Characterization of hot spots for natural chloroform formation: Relevance for groundwater quality

NASA Astrophysics Data System (ADS)

Jacobsen, Ole S.; Albers, Christian N.; Laier, Troels

2015-04-01

Chloroform soil hot spot may deteriorate groundwater quality and may even result in chloroform concentration exceeding the Danish maximum limit of 1 µg/L in groundwater for potable use. In order to characterize the soil properties important for the chloroform production, various ecosystems were examined with respect to soil air chloroform and soil organic matter type and content. Coniferous forest areas, responsible for highest chloroform concentrations, were examined on widely different scales from km to cm scale. Furthermore, regular soil gas measurements including chloroform were performed during 4 seasons at various depths, together with various meteorological measurements and soil temperature recordings. Laboratory incubation experiments were also performed on undisturbed soil samples in order to examine the role of various microbiota, fungi and bacteria. To identify hot spots responsible for the natural contamination we have measured the production of chloroform in the upper soil from different terrestrial systems. Field measurements of chloroform in top soil air were used as production indicators. The production was however not evenly distributed at any scale. The ecosystems seem to have quite different net-productions of chloroform from very low in grassland to very high in some coniferous forests. Within the forest ecosystem we found large variation in chloroform concentrations depending on vegetation. In beech forest we found the lowest values, somewhat higher in an open pine forest, but the highest concentrations were detected in spruce forest without any vegetation beneath. Within this ecotype, it appeared that the variation was also large; hot spots with 2-4 decades higher production than the surrounding area. These hot spots were not in any way visually different from the surroundings and were of variable size from 3 to 20 meters in diameter. Besides this, measurements within a seemingly homogenous hot spot showed that there was still high variability at 10 cm level. We suggest that the mechanism behind the formation of chloroform is an unspecific chlorination of organic matter, caused by microbial activity in the soil forming trichloroacetyl compounds. Laboratory measurements on intact soil cores have identified that the F and H horizons in the forest soil are the main producers of chloroform. Despite various attempts to identify the mechanisms responsible for the variability within a visually and chemically homogeneous area we have not yet succeeded. Parameters like soil respiration, inorganic and total organic chlorine, organic matter and soil structure were studied without any significant difference in favour of hot spots. By the use of 13C-isotopes we could identify the natural origin of the chloroform, and over a three years period we could conclude that the hot spots were permanent on the sites. At the same time a significant seasonal variation were measured depending on temperature and soil moisture.

Mitigation of Hot-Spots in Photovoltaic Systems Using Distributed Power Electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olalla, Carlos; Hasan, Md. Nazmul; Deline, Chris

In the presence of partial shading and other mismatch factors, bypass diodes may not offer complete elimination of excessive power dissipation due to cell reverse biasing, commonly referred to as hot-spotting in photovoltaic (PV) systems. As a result, PV systems may experience higher failure rates and accelerated ageing. In this paper, a cell-level simulation model is used to assess occurrence of hot-spotting events in a representative residential rooftop system scenario featuring a moderate shading environment. The approach is further used to examine how well distributed power electronics converters mitigate the effects of partial shading and other sources of mismatch bymore » preventing activation of bypass diodes and thereby reducing the chances of heavy power dissipation and hot-spotting in mismatched cells. The simulation results confirm that the occurrence of heavy power dissipation is reduced in all distributed power electronics architectures, and that submodule-level converters offer nearly 100% mitigation of hot-spotting. In addition, the paper further elaborates on the possibility of hot-spot-induced permanent damage, predicting a lifetime energy loss above 15%. In conclusion, this energy loss is fully recoverable with submodule-level power converters that mitigate hot-spotting and prevent the damage.« less

Mitigation of Hot-Spots in Photovoltaic Systems Using Distributed Power Electronics

DOE PAGES

Olalla, Carlos; Hasan, Md. Nazmul; Deline, Chris; ...

2018-03-23

In the presence of partial shading and other mismatch factors, bypass diodes may not offer complete elimination of excessive power dissipation due to cell reverse biasing, commonly referred to as hot-spotting in photovoltaic (PV) systems. As a result, PV systems may experience higher failure rates and accelerated ageing. In this paper, a cell-level simulation model is used to assess occurrence of hot-spotting events in a representative residential rooftop system scenario featuring a moderate shading environment. The approach is further used to examine how well distributed power electronics converters mitigate the effects of partial shading and other sources of mismatch bymore » preventing activation of bypass diodes and thereby reducing the chances of heavy power dissipation and hot-spotting in mismatched cells. The simulation results confirm that the occurrence of heavy power dissipation is reduced in all distributed power electronics architectures, and that submodule-level converters offer nearly 100% mitigation of hot-spotting. In addition, the paper further elaborates on the possibility of hot-spot-induced permanent damage, predicting a lifetime energy loss above 15%. In conclusion, this energy loss is fully recoverable with submodule-level power converters that mitigate hot-spotting and prevent the damage.« less

A hot spot for systemic lupus erythematosus, but not for psoriatic arthritis, identified by spatial analysis suggests an interaction between ethnicity and place of residence.

PubMed

Al-Maini, Mustafa; Jeyalingam, Thurarshen; Brown, Patrick; Lee, Jennifer J Y; Li, Lennon; Su, Jiandong; Gladman, Dafna D; Fortin, Paul R

2013-06-01

To describe the spatial distribution of incident cases of systemic lupus erythematosus (SLE) using geographic information systems (GIS). Spatial analyses were carried out on 890 SLE patients and 541 psoriatic arthritis (PsA) patients (controls). Age- and sex-adjusted rates for SLE/PsA for each census tract were calculated using denominator population values from the Canadian census. Spatial variations in relative risk were estimated by modeling risk as the product of a time effect, an age effect, and a spatially autocorrelated risk surface to identify hot spots. Patients within the detected hot spot were compared to those outside the hot spot to identify explanatory factors. SLE patients were predominantly female (87.75%) and the incidence rate was highest among those 15-19 years of age (2.4 cases/100,000 person-years). In an SLE hot spot containing 59 patients, 100% of the patients were female and 49.1% (n = 29) were Caucasian, while outside of the hot spot, 86.9% (n = 722) of the patients were female and 68.4% (n = 568) were Caucasian. The proportion of cases of Chinese ethnicity was significantly greater within the hot spot. An interaction was found between Chinese ethnicity and residence within the hot spot, with the risk of SLE to the Chinese population found to be twice the risk to the non-Chinese population. GIS was used to map SLE cases and a hot spot was identified after adjustment for age and sex. Ethnicity by itself did not confer an increased risk of SLE, but the interaction of ethnicity with location of residence significantly increased the risk of SLE. Copyright © 2013 by the American College of Rheumatology.

Two New Hot Spots on Io

NASA Image and Video Library

1998-03-26

The Near-Infrared Mapping Spectrometer (NIMS) on Galileo obtained this image of half of Io's disk in darkness on September 19, 1997. This image, at 5 microns, shows several hot spots on Io, which are volcanic regions of enhanced thermal emission. The area shown is part of the leading hemisphere of Io. Two new hot spots are shown and indicated in the image (New, and Shamshu). Neither of these hot spots were seen by NIMS or the Solid State Imaging Experiment, (SSI) prior to this observation, becoming only recently active. Several other previously known hot spots are labelled in the image. Galileo was at a distance of 342,000 km from Io when this observation was made. http://photojournal.jpl.nasa.gov/catalog/PIA01226

Thermally-Driven Mantle Plumes Reconcile Hot-spot Observations

NASA Astrophysics Data System (ADS)

Davies, D.; Davies, J.

2008-12-01

Hot-spots are anomalous regions of magmatism that cannot be directly associated with plate tectonic processes (e.g. Morgan, 1972). They are widely regarded as the surface expression of upwelling mantle plumes. Hot-spots exhibit variable life-spans, magmatic productivity and fixity (e.g. Ito and van Keken, 2007). This suggests that a wide-range of upwelling structures coexist within Earth's mantle, a view supported by geochemical and seismic evidence, but, thus far, not reproduced by numerical models. Here, results from a new, global, 3-D spherical, mantle convection model are presented, which better reconcile hot-spot observations, the key modification from previous models being increased convective vigor. Model upwellings show broad-ranging dynamics; some drift slowly, while others are more mobile, displaying variable life-spans, intensities and migration velocities. Such behavior is consistent with hot-spot observations, indicating that the mantle must be simulated at the correct vigor and in the appropriate geometry to reproduce Earth-like dynamics. Thermally-driven mantle plumes can explain the principal features of hot-spot volcanism on Earth.

Thermal Infrared Hot Spot and Dependence on Canopy Geometry

NASA Technical Reports Server (NTRS)

Smith, James A.; Ballard, Jerrell R., Jr.; Smith, David E. (Technical Monitor)

2001-01-01

We perform theoretical calculations of the canopy thermal infrared (TIR) hot spot using a first principles 3-D model described earlier. Various theoretical canopies of varying leaf size and for differing canopy height are used to illustrate the magnitude of the TIR effect. Our results are similar to predicted behavior in the reflective hot spot as a function of canopy geometry and comparable to TIR measurements from the literature and our own simple ground experiments. We apply the MODTRAN atmospheric code to estimate the at-sensor variation in brightness temperature with view direction in the solar principal plane. For simple homogeneous canopies, we predict canopy thermal infrared hot spot variations of 2 degrees C at the surface with respect to nadir viewing. Dependence on leaf size is weak as long as the ratio of leaf size to canopy height is maintained. However, the angular width of the hot spot increases as the ratio of leaf diameter to canopy height increases. Atmospheric effects minimize but do not eliminate the TIR hot spot at satellite altitudes.

Hot Spots on Io: Correlation of Infrared Emission and Visible Reflectance

NASA Technical Reports Server (NTRS)

Mcewen, A. S.; Soderblom, L.; Matson, D. L.; Johnson, T. V.

1985-01-01

The Voyager 1 infrared spectrometer (IRIS) data and two recently compiled data sets (Voyager imaging mosaics and measurements of Io's thermal emission from the NASA Infrared Telescope Facility) are correlated. These data were used to refine the correlation between dark spot optical properties (albedo and color) and thermal emission, to examine this correspondence on a satellite-wide scale, and to identify additional hot spots not included in the IRIS inventory. The results suggest the hot spots are liquid sulfur lava lakes, for the following reasons: (1) the melting point of sulfur is 390 K, and the model hot spot temperatures range from approximately 200 to 450 K; (2) the albedos and color of the dark spots, measured from the global mosaics, are consistent with laboratory measurements for liquid sulfur; (3) high resolution images of the dark features show morphologies suggestive of lava lakes; and (4) this hypothesis provides a simple and direct explanation for why dark spots are hot on Io.

The Earth's Hot Spots.

ERIC Educational Resources Information Center

Vink, Gregory E.; And Others

1985-01-01

Hot spots are isolated areas of geologic activity where volcanic eruptions, earthquakes, and upwelling currents occur far from plate boundaries. These mantle plumes are relatively stable and crustal plates drift over them. The nature and location of hot spots (with particular attention to the Hawaiian Islands and Iceland) are discussed. (DH)

Hot spots of Io

NASA Technical Reports Server (NTRS)

Pearl, J. C.; Sinton, W. M.

1982-01-01

The size and temperature, morphology and distribution, variability, possible absorption features, and processes of hot spots on Io are discussed, and an estimate of the global heat flux is made. Size and temperature information is deconvolved to obtain equivalent radius and temperature of hot spots, and simultaneously obtained Voyager thermal and imaging data is used to match hot sources with specific geologic features. In addition to their thermal output, it is possible that hot spots are also characterized by production of various gases and particulate materials; the spectral signature of SO2 has been seen. Origins for relatively stable, low temperature sources, transient high temperature sources, and relatively stable, high-tmperature sources are discussed.

Prediction of protein interaction hot spots using rough set-based multiple criteria linear programming.

PubMed

Chen, Ruoying; Zhang, Zhiwang; Wu, Di; Zhang, Peng; Zhang, Xinyang; Wang, Yong; Shi, Yong

2011-01-21

Protein-protein interactions are fundamentally important in many biological processes and it is in pressing need to understand the principles of protein-protein interactions. Mutagenesis studies have found that only a small fraction of surface residues, known as hot spots, are responsible for the physical binding in protein complexes. However, revealing hot spots by mutagenesis experiments are usually time consuming and expensive. In order to complement the experimental efforts, we propose a new computational approach in this paper to predict hot spots. Our method, Rough Set-based Multiple Criteria Linear Programming (RS-MCLP), integrates rough sets theory and multiple criteria linear programming to choose dominant features and computationally predict hot spots. Our approach is benchmarked by a dataset of 904 alanine-mutated residues and the results show that our RS-MCLP method performs better than other methods, e.g., MCLP, Decision Tree, Bayes Net, and the existing HotSprint database. In addition, we reveal several biological insights based on our analysis. We find that four features (the change of accessible surface area, percentage of the change of accessible surface area, size of a residue, and atomic contacts) are critical in predicting hot spots. Furthermore, we find that three residues (Tyr, Trp, and Phe) are abundant in hot spots through analyzing the distribution of amino acids. Copyright © 2010 Elsevier Ltd. All rights reserved.

Infrared characterization of thermal gradients on disc brakes

NASA Astrophysics Data System (ADS)

Panier, Stephane; Dufrenoy, Philippe; Bremond, Pierre

2003-04-01

The heat generated in frictional organs like brakes and clutches induces thermal distortions which may lead to localized contact areas and hot spots developments. Hot spots are high thermal gradients on the rubbing surface. They count among the most dangerous phenomena in frictional organs leading to damage, early failure and unacceptable braking performances such as brake fade or undesirable low frequency vibrations called hot judder. In this paper, an experimental study of hot spots occurrence in railway disc brakes is reported on. The aim of this study was to better classify and to explain the thermal gradients appearance on the surface of the disc. Thermograph measurements with an infrared camera have been carried out on the rubbing surface of brake discs on a full-scale test bench. The infrared system was set to take temperature readings in snap shot mode precisely synchronized with the rotation of the disc. Very short integration time allows reducing drastically haziness of thermal images. Based on thermographs, a classification of hot-spots observed in disc brakes is proposed. A detailed investigation of the most damaging thermal gradients, called macroscopic hot spots (MHS) is given. From these experimental researches, a scenario of hot spots occurrence is suggested step by step. Thanks to infrared measurements at high frequency with high resolution, observations give new highlights on the conditions of hot spots appearance. Comparison of the experimental observations with the theoretical approaches is finally discussed.

Numerical modeling of the sensitivity of x-ray driven implosions to low-mode flux asymmetries.

PubMed

Scott, R H H; Clark, D S; Bradley, D K; Callahan, D A; Edwards, M J; Haan, S W; Jones, O S; Spears, B K; Marinak, M M; Town, R P J; Norreys, P A; Suter, L J

2013-02-15

The sensitivity of inertial confinement fusion implosions, of the type performed on the National Ignition Facility (NIF) [1], to low-mode flux asymmetries is investigated numerically. It is shown that large-amplitude, low-order mode shapes (Legendre polynomial P(4), resulting from low-order flux asymmetries, cause spatial variations in capsule and fuel momentum that prevent the deuterium and tritium (DT) "ice" layer from being decelerated uniformly by the hot spot pressure. This reduces the transfer of implosion kinetic energy to internal energy of the central hot spot, thus reducing the neutron yield. Furthermore, synthetic gated x-ray images of the hot spot self-emission indicate that P(4) shapes may be unquantifiable for DT layered capsules. Instead the positive P(4) asymmetry "aliases" itself as an oblate P(2) in the x-ray images. Correction of this apparent P(2) distortion can further distort the implosion while creating a round x-ray image. Long wavelength asymmetries may be playing a significant role in the observed yield reduction of NIF DT implosions relative to detailed postshot two-dimensional simulations.

Identification of a Non-Gatekeeper Hot Spot for Drug-Resistant Mutations in mTOR Kinase.

PubMed

Wu, Tzung-Ju; Wang, Xiaowen; Zhang, Yanjie; Meng, Linghua; Kerrigan, John E; Burley, Stephen K; Zheng, X F Steven

2015-04-21

Protein kinases are therapeutic targets for human cancer. However, "gatekeeper" mutations in tyrosine kinases cause acquired clinical resistance, limiting long-term treatment benefits. mTOR is a key cancer driver and drug target. Numerous small-molecule mTOR kinase inhibitors have been developed, with some already in human clinical trials. Given our clinical experience with targeted therapeutics, acquired drug resistance in mTOR is thought likely, but not yet documented. Herein, we describe identification of a hot spot (L2185) for drug-resistant mutations, which is distinct from the gatekeeper site, and a chemical scaffold refractory to drug-resistant mutations. We also provide new insights into mTOR kinase structure and function. The hot spot mutations are potentially useful as surrogate biomarkers for acquired drug resistance in ongoing clinical trials and future treatments and for the design of the next generation of mTOR-targeted drugs. Our study provides a foundation for further research into mTOR kinase function and targeting. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

A small-area study of environmental risk assessment of outdoor falls.

PubMed

Lai, Poh-Chin; Wong, Wing-Cheung; Low, Chien-Tat; Wong, Martin; Chan, Ming-Houng

2011-12-01

Falls in public places are an issue of great health concern especially for the elderly. Falls among the elderly is also a major health burden in many countries. This study describes a spatial approach to assess environmental causes of outdoor falls using a small urban community in Hong Kong as an example. The method involves collecting data on fall occurrences and mapping their geographic positions to examine circumstances and environmental evidence that contribute to falls. High risk locations or hot spots of falls are identified on the bases of spatial proximity and concentration of falls within a threshold distance by means of kernel smoothing and standard deviational ellipses. This method of geographic aggregation of individual fall incidents for a small-area study yields hot spots of manageable sizes. The spatial clustering approach is effective in two ways. Firstly, it allows visualisation and isolation of fall hot spots to draw focus. Secondly and especially under conditions of resource decline, policy makers are able to target specific locations to examine the underlying causal mechanisms and strategise effective response and preventive measures based on the types of environmental risk factors identified.

Evaluation of the physical process controlling beach changes adjacent to nearshore dredge pits

USGS Publications Warehouse

Benedet, L.; List, J.H.

2008-01-01

Numerical modeling of a beach nourishment project is conducted to enable a detailed evaluation of the processes associated with the effects of nearshore dredge pits on nourishment evolution and formation of erosion hot spots. A process-based numerical model, Delft3D, is used for this purpose. The analysis is based on the modification of existing bathymetry to simulate "what if" scenarios with/without the bathymetric features of interest. Borrow pits dredged about 30??years ago to provide sand for the nourishment project have a significant influence on project performance and formation of erosional hot spots. It was found that the main processes controlling beach response to these offshore bathymetric features were feedbacks between wave forces (roller force or alongshore component of the radiation stress), pressure gradients due to differentials in wave set-up/set-down and bed shear stress. Modeling results also indicated that backfilling of selected borrow sites showed a net positive effect within the beach fill limits and caused a reduction in the magnitude of hot spot erosion. ?? 2008 Elsevier B.V. All rights reserved.

Systems and methods for photovoltaic string protection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krein, Philip T.; Kim, Katherine A.; Pilawa-Podgurski, Robert C. N.

A system and method includes a circuit for protecting a photovoltaic string. A bypass switch connects in parallel to the photovoltaic string and a hot spot protection switch connects in series with the photovoltaic string. A first control signal controls opening and closing of the bypass switch and a second control signal controls opening and closing of the hot spot protection switch. Upon detection of a hot spot condition the first control signal closes the bypass switch and after the bypass switch is closed the second control signal opens the hot spot protection switch.

Calculation of TIR Canopy Hot Spot and Implications for Earth Radiation Budget

NASA Technical Reports Server (NTRS)

Smith, J. A.; Ballard, J. R., Jr.

2000-01-01

Using a 3-D model for thermal infrared exitance and the Lowtran 7 atmospheric radiative transfer model, we compute the variation in brightness temperature with view direction and, in particular, the canopy thermal hot spot. We then perform a sensitivity analysis of surface energy balance components for a nominal case using a simple SVAT model given the uncertainty in canopy temperature arising from the thermal hot spot effect. Canopy thermal hot spot variations of two degrees C lead to differences of plus or minus 24% in the midday available energy.

Hot spot formation and stagnation properties in simulations of direct-drive NIF implosions

NASA Astrophysics Data System (ADS)

Schmitt, Andrew J.; Obenschain, Stephen P.

2016-05-01

We investigate different proposed methods of increasing the hot spot energy and radius in inertial confinement fusion implosions. In particular, shock mistiming (preferentially heating the inner edge of the target's fuel) and increasing the initial vapor gas density are investigated as possible control mechanisms. We find that only the latter is effective in substantially increasing the hot spot energy and dimensions while achieving ignition. In all cases an increase in the hot spot energy is accompanied by a decrease in the hot spot energy density (pressure) and both the yield and the gain of the target drop substantially. 2D simulations of increased vapor density targets predict an increase in the robustness of the target with respect to surface perturbations but are accompanied by significant yield degradation.

Calculation of the fast ion tail distribution for a spherically symmetric hot spot

NASA Astrophysics Data System (ADS)

McDevitt, C. J.; Tang, X.-Z.; Guo, Z.; Berk, H. L.

2014-10-01

The fast ion tail for a spherically symmetric hot spot is computed via the solution of a simplified Fokker-Planck collision operator. Emphasis is placed on describing the energy scaling of the fast ion distribution function in the hot spot as well as the surrounding cold plasma throughout a broad range of collisionalities and temperatures. It is found that while the fast ion tail inside the hot spot is significantly depleted, leading to a reduction of the fusion yield in this region, a surplus of fast ions is observed in the neighboring cold plasma region. The presence of this surplus of fast ions in the neighboring cold region is shown to result in a partial recovery of the fusion yield lost in the hot spot.

Distribution of flares on the sun during 1955-1985 - 'Hot spots' (active zones) lasting for 30 years

NASA Technical Reports Server (NTRS)

Bai, Taeil

1988-01-01

The coordinates of 'major solar flares' observed during the period from January 1955 through August 1985 are analyzed. About 100 'superactive' regions (large, complex, active regions containing large sunspots) produced 46 percent of the major flares during the period. Superactive regions appeared more frequently in certain areas of the sun called 'hot spots' or 'active zones'. The synodic rotation periods of the northern and southern hemisphere hot spots were 26.72 d and 26.61 d, respectively. One of the two hot spots persisted through three solar cycles, and the other was active during cycles 19 and 21 but was dormant during cycle 20. These findings suggest that the mechanism producing hot spots must be stable for two or three solar cycles or longer.

The hot-spot environment of SW Sex in a low state

NASA Astrophysics Data System (ADS)

Groot, Paul J.; Rutten, René G. M.; van Paradijs, Jan

2000-04-01

Based on observations obtained with the 2.5m Isaac Newton Telescope we show that the characteristics of the SW Sex stars can be explained by the dominance of a `hot-spot' like feature in the accretion disk. In SW Sex this `hot-spot' region is located at a distance of 0.5 RL 1 from the white-dwarf and is best visible at phase ϕ=0.95. The location of the hot-spot as deduced from spectral eclipse mapping coincides with the formation site of the main emission lines. We deduce that this hot-spot region is formed by a shock, which we speculate to be the consequence of a high mass-transfer rate and a long spin-period of the non-magnetic white dwarf.

Predicting hot spots in protein interfaces based on protrusion index, pseudo hydrophobicity and electron-ion interaction pseudopotential features

PubMed Central

Xia, Junfeng; Yue, Zhenyu; Di, Yunqiang; Zhu, Xiaolei; Zheng, Chun-Hou

2016-01-01

The identification of hot spots, a small subset of protein interfaces that accounts for the majority of binding free energy, is becoming more important for the research of drug design and cancer development. Based on our previous methods (APIS and KFC2), here we proposed a novel hot spot prediction method. For each hot spot residue, we firstly constructed a wide variety of 108 sequence, structural, and neighborhood features to characterize potential hot spot residues, including conventional ones and new one (pseudo hydrophobicity) exploited in this study. We then selected 3 top-ranking features that contribute the most in the classification by a two-step feature selection process consisting of minimal-redundancy-maximal-relevance algorithm and an exhaustive search method. We used support vector machines to build our final prediction model. When testing our model on an independent test set, our method showed the highest F1-score of 0.70 and MCC of 0.46 comparing with the existing state-of-the-art hot spot prediction methods. Our results indicate that these features are more effective than the conventional features considered previously, and that the combination of our and traditional features may support the creation of a discriminative feature set for efficient prediction of hot spots in protein interfaces. PMID:26934646

A comprehensive alpha-heating model for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christopherson, A. R.; Betti, R.; Bose, A.

In this paper, a comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot confined by a compressible shell, heated by fusion alphas, and cooled by radiation and thermal losses. The model includes the deceleration, stagnation, and burn phases of inertial confinement fusion implosions, and is valid for sub-ignited targets with ≤10× amplification of the fusion yield from alpha-heating. The results of radiation-hydrodynamic simulations are used to derive realistic initial conditions and dimensionless parameters for the model. It is found that most of the alpha energy (~90%) producedmore » before bang time is deposited within the hot spot mass, while a small fraction (~10%) drives mass ablation off the inner shell surface and its energy is recycled back into the hot spot. Of the bremsstrahlung radiation emission, ~40% is deposited in the hot spot, ~40% is recycled back in the hot spot by ablation off the shell, and ~20% leaves the hot spot. We show here that the hot spot, shocked shell, and outer shell trajectories from this analytical model are in good agreement with simulations. Finally, a detailed discussion of the effect of alpha-heating on the hydrodynamics is also presented.« less

A comprehensive alpha-heating model for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Christopherson, A. R.; Betti, R.; Bose, A.; Howard, J.; Woo, K. M.; Campbell, E. M.; Sanz, J.; Spears, B. K.

2018-01-01

A comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot confined by a compressible shell, heated by fusion alphas, and cooled by radiation and thermal losses. The model includes the deceleration, stagnation, and burn phases of inertial confinement fusion implosions, and is valid for sub-ignited targets with ≤10 × amplification of the fusion yield from alpha-heating. The results of radiation-hydrodynamic simulations are used to derive realistic initial conditions and dimensionless parameters for the model. It is found that most of the alpha energy (˜90%) produced before bang time is deposited within the hot spot mass, while a small fraction (˜10%) drives mass ablation off the inner shell surface and its energy is recycled back into the hot spot. Of the bremsstrahlung radiation emission, ˜40% is deposited in the hot spot, ˜40% is recycled back in the hot spot by ablation off the shell, and ˜20% leaves the hot spot. We show here that the hot spot, shocked shell, and outer shell trajectories from this analytical model are in good agreement with simulations. A detailed discussion of the effect of alpha-heating on the hydrodynamics is also presented.

A measurement concept for hot-spot BRDFs from space

NASA Technical Reports Server (NTRS)

Gerstl, S.A.W.

1996-01-01

Several concepts for canopy hot-spot measurements from space have been investigated. The most promising involves active illumination and bistatic detection that would allow hot-spot angular distribution (BRDF) measurements from space in a search-light mode. The concept includes a pointable illumination source, such as a laser operating at an atmospheric window wavelength, coupled with a number of high spatial-resolution detectors that are clustered around the illumination source in space, receiving photons nearly coaxial with the reto-reflection direction. Microwave control and command among the satellite cluster would allow orienting the direction of the laser beam as well as the focusing detectors simultaneously so that the coupled system can function like a search light with almost unlimited pointing capabilities. The concept is called the Hot-Spot Search-Light (HSSL) satellite. A nominal satellite altitude of 600 km will allow hot-spot BRDF measurements out to about 18 degrees phase angle. The distributed are taking radiometric measurements of the intensity wings of the hot-spot angular distribution without the need for complex imaging detectors. The system can be operated at night for increased signal-to-noise ratio. This way the hot-spot angular signatures can be quantified and parameterized in sufficient detail to extract the biophysical information content of plant architectures.

A comprehensive alpha-heating model for inertial confinement fusion

DOE PAGES

Christopherson, A. R.; Betti, R.; Bose, A.; ...

2018-01-08

In this paper, a comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot confined by a compressible shell, heated by fusion alphas, and cooled by radiation and thermal losses. The model includes the deceleration, stagnation, and burn phases of inertial confinement fusion implosions, and is valid for sub-ignited targets with ≤10× amplification of the fusion yield from alpha-heating. The results of radiation-hydrodynamic simulations are used to derive realistic initial conditions and dimensionless parameters for the model. It is found that most of the alpha energy (~90%) producedmore » before bang time is deposited within the hot spot mass, while a small fraction (~10%) drives mass ablation off the inner shell surface and its energy is recycled back into the hot spot. Of the bremsstrahlung radiation emission, ~40% is deposited in the hot spot, ~40% is recycled back in the hot spot by ablation off the shell, and ~20% leaves the hot spot. We show here that the hot spot, shocked shell, and outer shell trajectories from this analytical model are in good agreement with simulations. Finally, a detailed discussion of the effect of alpha-heating on the hydrodynamics is also presented.« less

Prediction of hot spots in protein interfaces using a random forest model with hybrid features.

PubMed

Wang, Lin; Liu, Zhi-Ping; Zhang, Xiang-Sun; Chen, Luonan

2012-03-01

Prediction of hot spots in protein interfaces provides crucial information for the research on protein-protein interaction and drug design. Existing machine learning methods generally judge whether a given residue is likely to be a hot spot by extracting features only from the target residue. However, hot spots usually form a small cluster of residues which are tightly packed together at the center of protein interface. With this in mind, we present a novel method to extract hybrid features which incorporate a wide range of information of the target residue and its spatially neighboring residues, i.e. the nearest contact residue in the other face (mirror-contact residue) and the nearest contact residue in the same face (intra-contact residue). We provide a novel random forest (RF) model to effectively integrate these hybrid features for predicting hot spots in protein interfaces. Our method can achieve accuracy (ACC) of 82.4% and Matthew's correlation coefficient (MCC) of 0.482 in Alanine Scanning Energetics Database, and ACC of 77.6% and MCC of 0.429 in Binding Interface Database. In a comparison study, performance of our RF model exceeds other existing methods, such as Robetta, FOLDEF, KFC, KFC2, MINERVA and HotPoint. Of our hybrid features, three physicochemical features of target residues (mass, polarizability and isoelectric point), the relative side-chain accessible surface area and the average depth index of mirror-contact residues are found to be the main discriminative features in hot spots prediction. We also confirm that hot spots tend to form large contact surface areas between two interacting proteins. Source data and code are available at: http://www.aporc.org/doc/wiki/HotSpot.

Automated quantification of proliferation with automated hot-spot selection in phosphohistone H3/MART1 dual-stained stage I/II melanoma.

PubMed

Nielsen, Patricia Switten; Riber-Hansen, Rikke; Schmidt, Henrik; Steiniche, Torben

2016-04-09

Staging of melanoma includes quantification of a proliferation index, i.e., presumed melanocytic mitoses of H&E stains are counted manually in hot spots. Yet, its reproducibility and prognostic impact increases by immunohistochemical dual staining for phosphohistone H3 (PHH3) and MART1, which also may enable fully automated quantification by image analysis. To ensure manageable workloads and repeatable measurements in modern pathology, the study aimed to present an automated quantification of proliferation with automated hot-spot selection in PHH3/MART1-stained melanomas. Formalin-fixed, paraffin-embedded tissue from 153 consecutive stage I/II melanoma patients was immunohistochemically dual-stained for PHH3 and MART1. Whole slide images were captured, and the number of PHH3/MART1-positive cells was manually and automatically counted in the global tumor area and in a manually and automatically selected hot spot, i.e., a fixed 1-mm(2) square. Bland-Altman plots and hypothesis tests compared manual and automated procedures, and the Cox proportional hazards model established their prognostic impact. The mean difference between manual and automated global counts was 2.9 cells/mm(2) (P = 0.0071) and 0.23 cells per hot spot (P = 0.96) for automated counts in manually and automatically selected hot spots. In 77 % of cases, manual and automated hot spots overlapped. Fully manual hot-spot counts yielded the highest prognostic performance with an adjusted hazard ratio of 5.5 (95 % CI, 1.3-24, P = 0.024) as opposed to 1.3 (95 % CI, 0.61-2.9, P = 0.47) for automated counts with automated hot spots. The automated index and automated hot-spot selection were highly correlated to their manual counterpart, but altogether their prognostic impact was noticeably reduced. Because correct recognition of only one PHH3/MART1-positive cell seems important, extremely high sensitivity and specificity of the algorithm is required for prognostic purposes. Thus, automated analysis may still aid and improve the pathologists' detection of mitoses in melanoma and possibly other malignancies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steward, G.; Mays, R. O.; Converse, M.

Microwave Interferometry (MI) offers the advantage of a continuous time measurement of detonation front velocity from detonation initiation to disassembly, which is an important step to assure the quality of stockpile high explosives. However, the method is currently characterized by areas of poor signal strength, which lead to low confidence measurements. Experiments in inert materials were conducted to determine if reflective hot spots, pockets of plasma that form during detonation, are responsible due to varying hot spot concentrations. Instead, it was found that the copper tube used in a range of standard HE test configurations is the cause of themore » poor signal reception. Hot spots were represented by microwave reflective aluminum particles. The aluminum was mixed with Titanium Dioxide, a material electrically similar to the insensitive high explosive, triaminotrinitrobenzene (TATB), in volume percent fractions (VPFs) between 0 and 100% aluminum, in increments of 10%. Reflectivity was measured based on input and reflection received from a test apparatus with a layer representing undetonated explosive and another representing an approaching shockwave. The results showed no correlation between VPF and measured reflectivity test cases while enclosed in the standard copper tube. Upon further testing, each sample’s measured reflectivity independent of the copper enclosure did correlate with VPF. This revealed that the test enclosure currently used for MI measurements is causing poor MI signal reception, and new methods must be developed to account for this aberration in MI measurements.« less

Potential hot spot for de novo mutations in PTCH1 gene in Gorlin syndrome patients: a case report of twins from Croatia.

PubMed

Musani, Vesna; Ozretić, Petar; Trnski, Diana; Sabol, Maja; Poduje, Sanja; Tošić, Mateja; Šitum, Mirna; Levanat, Sonja

2018-02-28

We describe a case of twins with sporadic Gorlin syndrome. Both twins had common Gorlin syndrome features including calcification of the falx cerebri, multiple jaw keratocysts, and multiple basal cell carcinomas, but with different expressivity. One brother also had benign testicular mesothelioma. We propose this tumor type as a possible new feature of Gorlin syndrome. Gorlin syndrome is a rare autosomal dominant disorder characterized by both developmental abnormalities and cancer predisposition, with variable expression of various developmental abnormalities and different types of tumors. The syndrome is primarily caused by mutations in the Patched 1 (PTCH1) gene, although rare mutations of Patched 2 (PTCH2) or Suppressor of Fused (SUFU) genes have also been found. Neither founder mutations nor hot spot locations have been described for PTCH1 in Gorlin syndrome patients. Although de novo mutations of the PTCH1 gene occur in almost 50% of Gorlin syndrome cases, there are a few recurrent mutations. Our twin patients were carriers of a de novo mutation in the PTCH1 gene, c.3364_3365delAT (p.Met1122ValfsX22). This is, to our knowledge, the first Gorlin syndrome-causing mutation that has been reported four independent times in distant geographical locations. Therefore, we propose the location of the described mutation as a potential hot spot for mutations in PTCH1.

THE IMPACT OF SURFACE TEMPERATURE INHOMOGENEITIES ON QUIESCENT NEUTRON STAR RADIUS MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elshamouty, K. G.; Heinke, C. O.; Morsink, S. M.

Fitting the thermal X-ray spectra of neutron stars (NSs) in quiescent X-ray binaries can constrain the masses and radii of NSs. The effect of undetected hot spots on the spectrum, and thus on the inferred NS mass and radius, has not yet been explored for appropriate atmospheres and spectra. A hot spot would harden the observed spectrum, so that spectral modeling tends to infer radii that are too small. However, a hot spot may also produce detectable pulsations. We simulated the effects of a hot spot on the pulsed fraction and spectrum of the quiescent NSs X5 and X7 inmore » the globular cluster 47 Tucanae, using appropriate spectra and beaming for hydrogen atmosphere models, incorporating special and general relativistic effects, and sampling a range of system angles. We searched for pulsations in archival Chandra HRC-S observations of X5 and X7, placing 90% confidence upper limits on their pulsed fractions below 16%. We use these pulsation limits to constrain the temperature differential of any hot spots, and to then constrain the effects of possible hot spots on the X-ray spectrum and the inferred radius from spectral fitting. We find that hot spots below our pulsation limit could bias the spectroscopically inferred radius downward by up to 28%. For Cen X-4 (which has deeper published pulsation searches), an undetected hot spot could bias its inferred radius downward by up to 10%. Improving constraints on pulsations from quiescent LMXBs may be essential for progress in constraining their radii.« less

What controls the distribution and tectono-magmatic features of oceanic hot spot volcanoes

NASA Astrophysics Data System (ADS)

Acocella, Valerio; Vezzoli, Luigina

2016-04-01

Hot spot oceanic volcanoes worldwide show significant deviations from the classic Hawaiian reference model; these mainly concern the distribution of edifices and overall tectono-magmatic features, as the development of the volcanic rift zones and extent of flank instability. Here we try to explain these deviations investigating and comparing the best-known hot spot oceanic volcanoes. At a general scale, these volcanoes show an age-distance progression ranging from focused to scattered. This is here explained as due to several independent factors, as the thermal or mechanical weakening of the plate (due to the lithosphere thickness or regional structures, respectively), or the plume structure. At a more detailed scale, hot spot volcanoes show recurrent features, including mafic shield edifices with summit caldera and volcanic rift zones, often at the head of an unstable flank. However, despite this recurrence, a widespread tectono-magmatic variability is often found. Here we show how this variability depends upon the magma supply and age of the oceanic crust (influencing the thickness of the overlying pelagic sediments). Well-developed rift zones and larger collapses are found on hot spot volcanoes with higher supply rate and older crust, as Hawaii and Canary Islands. Poorly-developed rift zones and limited collapses occur on hot spot volcanoes with lower supply rate and younger crust, as Easter Island and Ascension. Transitional features are observed at hot spots with intermediate productivity (Cape Verde, Reunion, Society Islands and, to a minor extent, the Azores), whereas the scarcity or absence of pelagic sediments may explain the lack of collapses and developed rift zones in the productive Galapagos hot spot.

Alternative hot spot formation techniques using liquid deuterium-tritium layer inertial confinement fusion capsules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, R. E.; Leeper, R. J.

2013-09-27

The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ~34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid”more » (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.« less

Alternative hot spot formation techniques using liquid deuterium-tritium layer inertial confinement fusion capsules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, R. E.; Leeper, R. J.

2013-09-15

The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ∼34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid”more » (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.« less

Magmatic effects of the Cobb hot spot on the Juan de Fuca Ridge

USGS Publications Warehouse

Chadwick, John; Perfit, M.; Ridley, I.; Jonasson, I.; Kamenov, G.; Chadwick, W.; Embley, R.; le, Roux P.; Smith, M.

2005-01-01

The interaction of the Juan de Fuca Ridge with the Cobb hot spot has had a considerable influence on the magmatism of the Axial Segment of the ridge, the second-order segment that overlies the hot spot. In addition to the construction of the large volcanic edifice of Axial Seamount, the Axial Segment has shallow bathymetry and a prevalence of constructional volcanic features along its 100-km length, suggesting that hot spot-derived magmas supplement and oversupply the ridge. Lavas are generally more primitive at Axial Seamount and more evolved in the Axial Segment rift zones, suggesting that fractional crystallization is enhanced with increasing distance from the hot spot because of a reduced magma supply and more rapid cooling. Although the Cobb hot spot is not an isotopically enriched plume, it produces lavas with some distinct geochemical characteristics relative to normal mid-ocean ridge basalt, such as enrichments in alkalis and highly incompatible trace elements, that can be used as tracers to identify the presence and prevalence of the hot spot influence along the ridge. These characteristics are most prominent at Axial Seamount and decline in gradients along the Axial Segment. The physical model that can best explain the geochemical observations is a scenario in which hot spot and mid-ocean ridge basalt (MORB) magmas mix to varying degrees, with the proportions controlled by the depth to the MORB source. Modeling of two-component mixing suggests that MORB is the dominant component in most Axial Segment basalts. Copyright 2005 by the American Geophysical Union.

A virus-binding hot spot on human angiotensin-converting enzyme 2 is critical for binding of two different coronaviruses.

PubMed

Wu, Kailang; Chen, Lang; Peng, Guiqing; Zhou, Wenbo; Pennell, Christopher A; Mansky, Louis M; Geraghty, Robert J; Li, Fang

2011-06-01

How viruses evolve to select their receptor proteins for host cell entry is puzzling. We recently determined the crystal structures of NL63 coronavirus (NL63-CoV) and SARS coronavirus (SARS-CoV) receptor-binding domains (RBDs), each complexed with their common receptor, human angiotensin-converting enzyme 2 (hACE2), and proposed the existence of a virus-binding hot spot on hACE2. Here we investigated the function of this hypothetical hot spot using structure-guided biochemical and functional assays. The hot spot consists of a salt bridge surrounded by hydrophobic tunnel walls. Mutations that disturb the hot spot structure have significant effects on virus/receptor interactions, revealing critical energy contributions from the hot spot structure. The tunnel structure at the NL63-CoV/hACE2 interface is more compact than that at the SARS-CoV/hACE2 interface, and hence RBD/hACE2 binding affinities are decreased either by NL63-CoV mutations decreasing the tunnel space or by SARS-CoV mutations increasing the tunnel space. Furthermore, NL63-CoV RBD inhibits hACE2-dependent transduction by SARS-CoV spike protein, a successful application of the hot spot theory that has the potential to become a new antiviral strategy against SARS-CoV infections. These results suggest that the structural features of the hot spot on hACE2 were among the driving forces for the convergent evolution of NL63-CoV and SARS-CoV.

Direct-Drive DT Cryogenic Implosion Performance with a Fill Tube

NASA Astrophysics Data System (ADS)

Regan, S. P.; Cao, D.; Goncharov, V. N.; Anderson, K. S.; Betti, R.; Bonino, M. J.; Campbell, E. M.; Collins, T. J. B.; Epstein, R.; Forrest, C. J.; Glebov, V. Yu.; Harding, D.; Hu, S. X.; Igumenshchev, I. V.; Marozas, J. A.; Marshall, F. J.; McKenty, P. W.; Radha, P. B.; Sangster, T. C.; Stoeckl, C.; Luo, R. W.; Tambazidis, A.; Schoff, M. E.; Farrell, M.

2017-10-01

The effects of a fill tube on the performance of direct-drive DT cryogenic implosions on the 60-beam, 30-kJ, 351-nm OMEGA laser are presented. The calculated adiabat, convergence ratio, and in-flight-aspect ratio quantities were 4, 17, and 23, respectively. Changes to the measured neutron yield, areal density, and ion temperature caused by the fill tube were found to be within experimental uncertainties. Gated x-ray images recorded during the acceleration phase at photon energies down to 1 keV show evidence of the fill tube perturbing the imploding shell and causing a region of enhanced emission from the hot spot, while gated x-ray images of the hot spot in the 4- to 8-keV photon energy range show no effect from the fill tube. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

"Hot spots" growth on single nanowire controlled by electric charge.

PubMed

Xi, Shaobo; Liu, Xuehua; He, Ting; Tian, Lei; Wang, Wenhui; Sun, Rui; He, Weina; Zhang, Xuetong; Zhang, Jinping; Ni, Weihai; Zhou, Xiaochun

2016-06-09

"Hot spots" - a kind of highly active site, which are usually composed of some unique units, such as defects, interfaces, catalyst particles or special structures - can determine the performance of nanomaterials. In this paper, we study a model system, i.e. "hot spots" on a single Ag nanowire in the galvanic replacement reaction (GRR), by dark-field microscopy. The research reveals that electric charge can be released by the formation reaction of AgCl, and consequently the electrochemical potential on Ag nanowire drops. The electric charge could induce the reduction of Ag(+) to form the "hot spots" on the nanowire during the GRR. The appearance probability of "hot spots" is almost even along the Ag nanowire, while it is slightly lower near the two ends. The spatial distance between adjacent "hot spots" is also controlled by the charge, and obeys a model based on Boltzmann distribution. In addition, the distance distribution here has an advantage in electron transfer and energy saving. Therefore, it's necessary to consider the functions of electric charge during the synthesis or application of nanomaterials.

EDF experience with {open_quotes}hot spot{close_quotes} management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guio, J.M. de

1995-03-01

During the past few years, {open_quotes}hot spots{close_quotes} due to the presence of particles of metal activated during their migration through the reactor core, have been detected at several French pressurized water reactor (PWR) units. These {open_quotes}hot spots,{close_quotes} which generate very high dose rates (from about 10 Gy/h to 200 G/h) are a significant factor in increase occupational exposures during outrates. Of particular concern are the difficult cases which prolong outage duration and increase the volume of radiological waste. Confronted with this situation, Electricite de France (EDF) has set up a national research group, as part of its ALARA program, tomore » establish procedures and techniques to avoid, detect, and eliminate of hot spots. In particular, specific processes have been developed to eliminate these hot spots which are most costly in terms of occupational exposure due to the need for reactor maintenance. This paper sets out the general approach adopted at EDF so far to cope with the problem of hot spots, illustrated by experience at Blayais 3 and 4.« less

Analytical modeling of the temporal evolution of hot spot temperatures in silicon solar cells

NASA Astrophysics Data System (ADS)

Wasmer, Sven; Rajsrima, Narong; Geisemeyer, Ino; Fertig, Fabian; Greulich, Johannes Michael; Rein, Stefan

2018-03-01

We present an approach to predict the equilibrium temperature of hot spots in crystalline silicon solar cells based on the analysis of their temporal evolution right after turning on a reverse bias. For this end, we derive an analytical expression for the time-dependent heat diffusion of a breakdown channel that is assumed to be cylindrical. We validate this by means of thermography imaging of hot spots right after turning on a reverse bias. The expression allows to be used to extract hot spot powers and radii from short-term measurements, targeting application in inline solar cell characterization. The extracted hot spot powers are validated at the hands of long-term dark lock-in thermography imaging. Using a look-up table of expected equilibrium temperatures determined by numerical and analytical simulations, we utilize the determined hot spot properties to predict the equilibrium temperatures of about 100 industrial aluminum back-surface field solar cells and achieve a high correlation coefficient of 0.86 and a mean absolute error of only 3.3 K.

Hot luminescence from gold nanoflowers and its application in high-density optical data storage.

PubMed

Zheng, Yunbao; Liu, Haiying; Xiang, Jin; Dai, Qiaofeng; Ouyang, Min; Tie, Shaolong; Lan, Sheng

2017-04-17

Gold nanoflowers with feature sizes ranging from several tenths to several hundred nanometers were synthesized by using the one-pot method. They were formed by the self-organization of gold nanoparticles of several nanometers and exhibited broad extinction spectra in the near infrared spectral range. Randomly distributed hot spots originating from the strongly localized modes were generated in gold nanoflowers and their appearances exhibited strong dependences on both the polarization and wavelength of the excitation light. Under the excitation of femtosecond laser pulses, such hot spots emitted efficient hot luminescence spanning the visible to near infrared spectral range. Distinct from the hot luminescence of single hot spots formed on rough gold and silver surfaces, the hot luminescence from gold nanoflowers composed of a large number of hot spots exhibited excitation-intensity dependence quite similar to the emission spectrum. It was demonstrated that the polarization- and wavelength-dependent hot luminescence of gold nanoflowers can be utilized to realize optical data storage with high density and low energy.

Hot spot formation from shock reflections

NASA Astrophysics Data System (ADS)

Menikoff, R.

2011-04-01

Heterogeneities sensitize an explosive to shock initiation. This is due to hot-spot formation and the sensitivity of chemical reaction rates to temperature. Here, we describe a numerical experiment aimed at elucidating a mechanism for hot-spot formation that occurs when a shock wave passes over a high-density impurity. The simulation performed is motivated by a physical experiment in which glass beads are added to liquid nitromethane. The impedance mismatch between the beads and the nitromethane results in shock reflections. These, in turn, give rise to transverse waves along the lead shock front. Hot spots arise on local portions of the lead front with a higher shock strength, rather than on the reflected shocks behind the beads. Moreover, the interactions generated by reflected waves from neighboring beads can significantly increase the peak hot-spot temperature when the beads are suitably spaced.

Determination of hot-spot susceptibility of multistring photovoltaic modules in a central-station application

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.; Weaver, R. W.; Ross, R. G., Jr.; Spencer, R.; Arnett, J. C.

1984-01-01

Part of the effort of the Jet Propulsion Laboratory (JPL) Flat-Plate Solar Array Project (FSA) includes a program to improve module and array reliability. A collaborative activity with industry dealing with the problem of hot-spot heating due to the shadowing of photovoltaic cells in modules and arrays containing several paralleled cell strings is described. The use of multiparallel strings in large central-station arrays introduces the likelihood of unequal current sharing and increased heating levels. Test results that relate power dissipated, current imbalance, cross-strapping frequency, and shadow configuration to hot-spot heating levels are presented. Recommendations for circuit design configurations appropriate to central-station applications that reduce the risk of hot-spot problems are offered. Guidelines are provided for developing hot-spot tests for arrays when current imbalance is a threat.

Focal areas of increased lipid concentration on the coating of microbubbles during short tone-burst ultrasound insonification.

PubMed

Kooiman, Klazina; van Rooij, Tom; Qin, Bin; Mastik, Frits; Vos, Hendrik J; Versluis, Michel; Klibanov, Alexander L; de Jong, Nico; Villanueva, Flordeliza S; Chen, Xucai

2017-01-01

Acoustic behavior of lipid-coated microbubbles has been widely studied, which has led to several numerical microbubble dynamics models that incorporate lipid coating behavior, such as buckling and rupture. In this study we investigated the relationship between microbubble acoustic and lipid coating behavior on a nanosecond scale by using fluorescently labeled lipids. It is hypothesized that a local increased concentration of lipids, appearing as a focal area of increased fluorescence intensity (hot spot) in the fluorescence image, is related to buckling and folding of the lipid layer thereby highly influencing the microbubble acoustic behavior. To test this hypothesis, the lipid microbubble coating was fluorescently labeled. The vibration of the microbubble (n = 177; 2.3-10.3 μm in diameter) upon insonification at an ultrasound frequency of 0.5 or 1 MHz at 25 or 50 kPa acoustic pressure was recorded with the UPMC Cam, an ultra-high-speed fluorescence camera, operated at ~4-5 million frames per second. During short tone-burst excitation, hot spots on the microbubble coating occurred at relative vibration amplitudes > 0.3 irrespective of frequency and acoustic pressure. Around resonance, the majority of the microbubbles formed hot spots. When the microbubble also deflated acoustically, hot spot formation was likely irreversible. Although compression-only behavior (defined as substantially more microbubble compression than expansion) and subharmonic responses were observed in those microbubbles that formed hot spots, both phenomena were also found in microbubbles that did not form hot spots during insonification. In conclusion, this study reveals hot spot formation of the lipid monolayer in the microbubble's compression phase. However, our experimental results show that there is no direct relationship between hot spot formation of the lipid coating and microbubble acoustic behaviors such as compression-only and the generation of a subharmonic response. Hence, our hypothesis that hot spots are related to acoustic buckling could not be verified.

Focal areas of increased lipid concentration on the coating of microbubbles during short tone-burst ultrasound insonification

PubMed Central

van Rooij, Tom; Qin, Bin; Mastik, Frits; Vos, Hendrik J.; Versluis, Michel; Klibanov, Alexander L.; de Jong, Nico; Villanueva, Flordeliza S.; Chen, Xucai

2017-01-01

Acoustic behavior of lipid-coated microbubbles has been widely studied, which has led to several numerical microbubble dynamics models that incorporate lipid coating behavior, such as buckling and rupture. In this study we investigated the relationship between microbubble acoustic and lipid coating behavior on a nanosecond scale by using fluorescently labeled lipids. It is hypothesized that a local increased concentration of lipids, appearing as a focal area of increased fluorescence intensity (hot spot) in the fluorescence image, is related to buckling and folding of the lipid layer thereby highly influencing the microbubble acoustic behavior. To test this hypothesis, the lipid microbubble coating was fluorescently labeled. The vibration of the microbubble (n = 177; 2.3–10.3 μm in diameter) upon insonification at an ultrasound frequency of 0.5 or 1 MHz at 25 or 50 kPa acoustic pressure was recorded with the UPMC Cam, an ultra-high-speed fluorescence camera, operated at ~4–5 million frames per second. During short tone-burst excitation, hot spots on the microbubble coating occurred at relative vibration amplitudes > 0.3 irrespective of frequency and acoustic pressure. Around resonance, the majority of the microbubbles formed hot spots. When the microbubble also deflated acoustically, hot spot formation was likely irreversible. Although compression-only behavior (defined as substantially more microbubble compression than expansion) and subharmonic responses were observed in those microbubbles that formed hot spots, both phenomena were also found in microbubbles that did not form hot spots during insonification. In conclusion, this study reveals hot spot formation of the lipid monolayer in the microbubble’s compression phase. However, our experimental results show that there is no direct relationship between hot spot formation of the lipid coating and microbubble acoustic behaviors such as compression-only and the generation of a subharmonic response. Hence, our hypothesis that hot spots are related to acoustic buckling could not be verified. PMID:28686673

Gluonic hot spots and spatial correlations inside the proton

NASA Astrophysics Data System (ADS)

Albacete, Javier L.; Petersen, Hannah; Soto-Ontoso, Alba

2017-11-01

In this work, largely based on [J. L. Albacete, A. Soto-Ontoso, Hot spots and the hollowness of proton-proton interactions at high energies, arXiv:1605.09176; J. L. Albacete, H. Petersen, A. Soto-Ontoso, Correlated wounded hot spots in proton-proton interactions, arXiv:1612.06274], we present a novel initial state geometry for proton-proton interactions. We rely on gluonic hot spots as effective degrees of freedom whose transverse positions inside the proton are correlated. We explore the impact of these non-trivial spatial correlations on the eccentricity and triangularity of the system following a Monte Carlo Glauber approach.

Hotspots and sunspots - Surface tracers of deep mantle convection in the earth and sun

NASA Technical Reports Server (NTRS)

Stothers, Richard B.

1993-01-01

The evolution of the hot-spot distribution on earth in time and space is investigated using available age data. The statistics of continental flood basalt eruptions suggests the formation of a total of about 40 hot spots worldwide during the Cenozoic and Mesozoic, with no true antipodal pairs found. It was found that hot spots tend to concentrate mainly in mid-latitudes, but the pattern of new appearances of hot spots may migrate from high to low latitudes in both hemispheres in long cycles, and may also drift in longitude, although much more slowly prograde.

Mean Streets and Mental Health: Depression and Post-Traumatic Stress Disorder at Crime Hot Spots.

PubMed

Weisburd, David; Cave, Breanne; Nelson, Matthew; White, Clair; Haviland, Amelia; Ready, Justin; Lawton, Brian; Sikkema, Kathleen

2018-03-07

This study explores the relationship between mental health and place at microgeographic units of analysis. We examine self-reported symptomology for depression and PTSD for 2,724 survey respondents interviewed in three types of randomly selected street segments: violent crime hot spots, cool spots, and cold spots. We find that the mean symptomology score is 61% higher for depression in violent crime hot spots than cold spots, and 85% higher for PTSD. Overall, we estimate that 14.8% of residents of violent crime hot spots meet thresholds for moderate depression or a diagnosis of PTSD. This can be compared to only 6.5% of residents at the cold spots. Using PSM and weighted negative binomial regression approaches we show that observable selection factors are not responsible for the relationships identified. Examining geographic influences, we find an important area effect of violent crime for both mental health measures, and an additional impact of the specific street of residence for PTSD. © Society for Community Research and Action 2018.

Repeat ridge jumps associated with plume-ridge interaction, melt transport, and ridge migration

NASA Astrophysics Data System (ADS)

Mittelstaedt, Eric; Ito, Garrett; van Hunen, Jeroen

2011-01-01

Repeated shifts, or jumps, of mid-ocean ridge segments toward nearby hot spots can produce large, long-term changes to the geometry and location of the tectonic plate boundaries. Ridge jumps associated with hot spot-ridge interaction are likely caused by several processes including shear on the base of the plate due to expanding plume material as well as reheating of lithosphere as magma passes through it to feed off-axis volcanism. To study how these processes influence ridge jumps, we use numerical models to simulate 2-D (in cross section) viscous flow of the mantle, viscoplastic deformation of the lithosphere, and melt migration upward from the asthenospheric melting zone, laterally along the base of the lithosphere, and vertically through the lithosphere. The locations and rates that magma penetrates and heats the lithosphere are controlled by the time-varying accumulation of melt beneath the plate and the depth-averaged lithospheric porosity. We examine the effect of four key parameters: magmatic heating rate of the lithosphere, plate spreading rate, age of the seafloor overlying the plume, and the plume-ridge migration rate. Results indicate that the minimum value of the magmatic heating rate needed to initiate a ridge jump increases with plate age and spreading rate. The time required to complete a ridge jump decreases with larger values of magmatic heating rate, younger plate age, and faster spreading rate. For cases with migrating ridges, models predict a range of behaviors including repeating ridge jumps, much like those exhibited on Earth. Repeating ridge jumps occur at moderate magmatic heating rates and are the result of changes in the hot spot magma flux in response to magma migration along the base of an evolving lithosphere. The tendency of slow spreading to promote ridge jumps could help explain the observed clustering of hot spots near the Mid-Atlantic Ridge. Model results also suggest that magmatic heating may significantly thin the lithosphere, as has been suggested at Hawaii and other hot spots.

Protein-protein interface analysis and hot spots identification for chemical ligand design.

PubMed

Chen, Jing; Ma, Xiaomin; Yuan, Yaxia; Pei, Jianfeng; Lai, Luhua

2014-01-01

Rational design for chemical compounds targeting protein-protein interactions has grown from a dream to reality after a decade of efforts. There are an increasing number of successful examples, though major challenges remain in the field. In this paper, we will first give a brief review of the available methods that can be used to analyze protein-protein interface and predict hot spots for chemical ligand design. New developments of binding sites detection, ligandability and hot spots prediction from the author's group will also be described. Pocket V.3 is an improved program for identifying hot spots in protein-protein interface using only an apo protein structure. It has been developed based on Pocket V.2 that can derive receptor-based pharmacophore model for ligand binding cavity. Given similarities and differences between the essence of pharmacophore and hot spots for guiding design of chemical compounds, not only energetic but also spatial properties of protein-protein interface are used in Pocket V.3 for dealing with protein-protein interface. In order to illustrate the capability of Pocket V.3, two datasets have been used. One is taken from ASEdb and BID having experimental alanine scanning results for testing hot spots prediction. The other is taken from the 2P2I database containing complex structures of protein-ligand binding at the original protein-protein interface for testing hot spots application in ligand design.

Comparison of the manual, semiautomatic, and automatic selection and leveling of hot spots in whole slide images for Ki-67 quantification in meningiomas.

PubMed

Swiderska, Zaneta; Korzynska, Anna; Markiewicz, Tomasz; Lorent, Malgorzata; Zak, Jakub; Wesolowska, Anna; Roszkowiak, Lukasz; Slodkowska, Janina; Grala, Bartlomiej

2015-01-01

Background. This paper presents the study concerning hot-spot selection in the assessment of whole slide images of tissue sections collected from meningioma patients. The samples were immunohistochemically stained to determine the Ki-67/MIB-1 proliferation index used for prognosis and treatment planning. Objective. The observer performance was examined by comparing results of the proposed method of automatic hot-spot selection in whole slide images, results of traditional scoring under a microscope, and results of a pathologist's manual hot-spot selection. Methods. The results of scoring the Ki-67 index using optical scoring under a microscope, software for Ki-67 index quantification based on hot spots selected by two pathologists (resp., once and three times), and the same software but on hot spots selected by proposed automatic methods were compared using Kendall's tau-b statistics. Results. Results show intra- and interobserver agreement. The agreement between Ki-67 scoring with manual and automatic hot-spot selection is high, while agreement between Ki-67 index scoring results in whole slide images and traditional microscopic examination is lower. Conclusions. The agreement observed for the three scoring methods shows that automation of area selection is an effective tool in supporting physicians and in increasing the reliability of Ki-67 scoring in meningioma.

Modeling deflagration waves out of hot spots

NASA Astrophysics Data System (ADS)

Partom, Yehuda

2017-01-01

It is widely accepted that shock initiation and detonation of heterogeneous explosives comes about by a two-step process known as ignition and growth. In the first step a shock sweeping through an explosive cell (control volume) creates hot spots that become ignition sites. In the second step, deflagration waves (or burn waves) propagate out of those hot spots and transform the reactant in the cell into reaction products. The macroscopic (or average) reaction rate of the reactant in the cell depends on the speed of those deflagration waves and on the average distance between neighboring hot spots. Here we simulate the propagation of deflagration waves out of hot spots on the mesoscale in axial symmetry using a 2D hydrocode, to which we add heat conduction and bulk reaction. The propagation speed of the deflagration waves may depend on both pressure and temperature. It depends on pressure for quasistatic loading near ambient temperature, and on temperature at high temperatures resulting from shock loading. From the simulation we obtain deflagration fronts emanating out of the hot spots. For 8 to 13 GPa shocks, the emanating fronts propagate as deflagration waves to consume the explosive between hot spots. For higher shock levels deflagration waves may interact with the sweeping shock to become detonation waves on the mesoscale. From the simulation results we extract average deflagration wave speeds.

Comparison of the Manual, Semiautomatic, and Automatic Selection and Leveling of Hot Spots in Whole Slide Images for Ki-67 Quantification in Meningiomas

PubMed Central

Swiderska, Zaneta; Korzynska, Anna; Markiewicz, Tomasz; Lorent, Malgorzata; Zak, Jakub; Wesolowska, Anna; Roszkowiak, Lukasz; Slodkowska, Janina; Grala, Bartlomiej

2015-01-01

Background. This paper presents the study concerning hot-spot selection in the assessment of whole slide images of tissue sections collected from meningioma patients. The samples were immunohistochemically stained to determine the Ki-67/MIB-1 proliferation index used for prognosis and treatment planning. Objective. The observer performance was examined by comparing results of the proposed method of automatic hot-spot selection in whole slide images, results of traditional scoring under a microscope, and results of a pathologist's manual hot-spot selection. Methods. The results of scoring the Ki-67 index using optical scoring under a microscope, software for Ki-67 index quantification based on hot spots selected by two pathologists (resp., once and three times), and the same software but on hot spots selected by proposed automatic methods were compared using Kendall's tau-b statistics. Results. Results show intra- and interobserver agreement. The agreement between Ki-67 scoring with manual and automatic hot-spot selection is high, while agreement between Ki-67 index scoring results in whole slide images and traditional microscopic examination is lower. Conclusions. The agreement observed for the three scoring methods shows that automation of area selection is an effective tool in supporting physicians and in increasing the reliability of Ki-67 scoring in meningioma. PMID:26240787

75 FR 9411 - Official Release of the MOVES2010 Motor Vehicle Emissions Model for Emissions Inventories in SIPs...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-02

... hot-spot analyses at this time; the Agency will approve the model for such analyses in the near future...-Level Conformity Hot-Spot Analyses Availability of MOVES2010 and Support Materials Copies of the... for regional emissions analyses and CO hot-spot analyses for transportation conformity (73 FR 3464...

New 40Ar/39Ar age progression for the Louisville hot spot trail and implications for inter-hot spot motion

NASA Astrophysics Data System (ADS)

Koppers, Anthony A. P.; Gowen, Molly D.; Colwell, Lauren E.; Gee, Jeffrey S.; Lonsdale, Peter F.; Mahoney, John J.; Duncan, Robert A.

2011-12-01

In this study we present 42 new 40Ar/39Ar incremental heating age determinations that contribute to an updated age progression for the Louisville seamount trail. Louisville is the South Pacific counterpart to the Hawaiian-Emperor seamount trail, both trails representing intraplate volcanism over the same time interval (˜80 Ma to present) and being examples of primary hot spot lineaments. Our data provide evidence for an age-progressive trend from 71 to 21 Ma. Assuming fixed hot spots, this makes possible a direct comparison to the Hawaiian-Emperor age progression and the most recent absolute plate motion (APM) model (WK08G) of Wessel and Kroenke (2008). We observe that for the Louisville seamount trail the measured ages are systematically older relative to both the WK08G model predictions and Hawaiian seamount ages, with offsets ranging up to 6 Myr. Taking into account the uncertainty about the duration of eruption and magmatic succession at individual Louisville volcanoes, these age offsets should be considered minimum estimates, as our sampling probably tended to recover the youngest lava flows. These large deviations point to either a contribution of inter-hot spot motion between the Louisville and Hawaiian hot spots or to a more easterly location of the Louisville hot spot than the one inferred in the WK08G model. Both scenarios are investigated in this paper, whereby the more eastern hot spot location (52.0°S, 134.5°W versus 52.4°S, 137.2°W) reduces the average age offset, but still results in a relatively large maximum offset of 3.7 Myr. When comparing the new ages to the APM models (S04P, S04G) by Steinberger et al. (2004) that attempt to compensate for the motion of hot spots in the Pacific (Hawaii) or globally (Hawaii, Louisville, Reunion and Walvis), the measured and predicted ages are more in agreement, showing only a maximum offset of 2.3 Myr with respect to the S04G model. At face value these more advanced APM models, which consider both plate and hot spot motions, therefore provide a better fit to the new Louisville age data. The fit is particularly good for seamounts younger than 50 Ma, a period for which there is little predicted motion for the Louisville hot spot and little inter-hot spot motion with Hawaii. However, discrepancies in the Louisville age-distance record prior to 50 Ma indicate there is an extra source of inter-hot spot motion between Louisville and the other Pacific hot spots that was not corrected for in the global S04G model. Finally, based on six new 40Ar/39Ar age dates, the 169°W bend in the Louisville seamount trail seems to have formed at least 3 Myr before the formation of the Hawaiian-Emperor bend. The timing of the most acute parts of both bends thus appears to be asynchronous, which would require other processes (e.g., plume motions) than a global plate motion change between 50 and 47 Ma to explain these two observations.

Comprehensive Experimental and Computational Analysis of Binding Energy Hot Spots at the NF-κB Essential Modulator (NEMO)/IKKβ Protein-Protein Interface

PubMed Central

Golden, Mary S.; Cote, Shaun M.; Sayeg, Marianna; Zerbe, Brandon S.; Villar, Elizabeth A.; Beglov, Dmitri; Sazinsky, Stephen L.; Georgiadis, Rosina M.; Vajda, Sandor; Kozakov, Dima; Whitty, Adrian

2013-01-01

We report a comprehensive analysis of binding energy hot spots at the protein-protein interaction (PPI) interface between NF-κB Essential Modulator (NEMO) and IκB kinase subunit β (IKKβ), an interaction that is critical for NF-κB pathway signaling, using experimental alanine scanning mutagenesis and also the FTMap method for computational fragment screening. The experimental results confirm that the previously identified NBD region of IKKβ contains the highest concentration of hot spot residues, the strongest of which are W739, W741 and L742 (ΔΔG = 4.3, 3.5 and 3.2 kcal/mol, respectively). The region occupied by these residues defines a potentially druggable binding site on NEMO that extends for ~16 Å to additionally include the regions that bind IKKβ L737 and F734. NBD residues D738 and S740 are also important for binding but do not make direct contact with NEMO, instead likely acting to stabilize the active conformation of surrounding residues. We additionally found two previously unknown hot spot regions centered on IKKβ residues L708/V709 and L719/I723. The computational approach successfully identified all three hot spot regions on IKKβ. Moreover, the method was able to accurately quantify the energetic importance of all hot spots residues involving direct contact with NEMO. Our results provide new information to guide the discovery of small molecule inhibitors that target the NEMO/IKKβ interaction. They additionally clarify the structural and energetic complementarity between “pocket-forming” and “pocket occupying” hot spot residues, and further validate computational fragment mapping as a method for identifying hot spots at PPI interfaces. PMID:23506214

Hot spot formation and chemical reaction initiation in shocked HMX crystals with nanovoids: a large-scale reactive molecular dynamics study.

PubMed

Zhou, Tingting; Lou, Jianfeng; Zhang, Yangeng; Song, Huajie; Huang, Fenglei

2016-07-14

We report million-atom reactive molecular dynamic simulations of shock initiation of β-cyclotetramethylene tetranitramine (β-HMX) single crystals containing nanometer-scale spherical voids. Shock induced void collapse and subsequent hot spot formation as well as chemical reaction initiation are observed which depend on the void size and impact strength. For an impact velocity of 1 km s(-1) and a void radius of 4 nm, the void collapse process includes three stages; the dominant mechanism is the convergence of upstream molecules toward the centerline and the downstream surface of the void forming flowing molecules. Hot spot formation also undergoes three stages, and the principal mechanism is kinetic energy transforming to thermal energy due to the collision of flowing molecules on the downstream surface. The high temperature of the hot spot initiates a local chemical reaction, and the breakage of the N-NO2 bond plays the key role in the initial reaction mechanism. The impact strength and void size have noticeable effects on the shock dynamical process, resulting in a variation of the predominant mechanisms leading to void collapse and hot spot formation. Larger voids or stronger shocks result in more intense hot spots and, thus, more violent chemical reactions, promoting more reaction channels and generating more reaction products in a shorter duration. The reaction products are mainly concentrated in the developed hot spot, indicating that the chemical reactivity of the hmx crystal is greatly enhanced by void collapse. The detailed information derived from this study can aid a thorough understanding of the role of void collapse in hot spot formation and the chemical reaction initiation of explosives.

Investigation of Jupiter's Equatorial Hotspots and Plumes Using Cassini ISS Observations

NASA Technical Reports Server (NTRS)

Choi, David S.; Showman, A. P.; Vasavada, A. R.; Simon-Miller, A. A.

2012-01-01

We present updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the ISS onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial 5-micron hot spots and their interactions with adjacent latitudes. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but a diffuse western edge serving as a nebulous boundary 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-iike 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. This raises the possibility that the plumes and fast-moving clouds are at higher altitudes, because their speed does not match previously published zonal wind profiles. Most 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 waves controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed. Instead, our expanded data set demonstrating the rapid flow of these scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. This research was supported by a NASA JDAP grant and the NASA Postdoctoral Program.

Ion distribution in the hot spot of an inertial confinement fusion plasma

NASA Astrophysics Data System (ADS)

Tang, Xianzhu; Guo, Zehua; Berk, Herb

2012-10-01

Maximizing the fusion gain of inertial confinement fusion (ICF) for inertial fusion energy (IFE) applications leads to the standard scenario of central hot spot ignition followed by propagating burn wave through the cold/dense assembled fuel. The fact that the hot spot is surrounded by cold but dense fuel layer introduces subtle plasma physics which requires a kinetic description. Here we perform Fokker-Planck calculations and kinetic PIC simulations for an ICF plasma initially in pressure balance but having large temperature gradient over a narrow transition layer. The loss of the fast ion tail from the hot spot, which is important for fusion reactivity, is quantified by Fokker-Planck models. The role of electron energy transport and the ambipolar electric field is investigated via kinetic simulations and the fluid moment models. The net effect on both hot spot ion temperature and the ion tail distribution, and hence the fusion reactivity, is elucidated.

Absence of ras-gene hot-spot mutations in canine fibrosarcomas and melanomas.

PubMed

Murua Escobar, Hugo; Günther, Kathrin; Richter, Andreas; Soller, Jan T; Winkler, Susanne; Nolte, Ingo; Bullerdiek, Jörn

2004-01-01

Point mutations within ras proto-oncogenes, particularly within the mutational hot-spot codons 12, 13 and 61, are frequently detected in human malignancies and in different types of experimentally-induced tumours in animals. So far little is known about ras mutations in naturally occurring canine fibrosarcomas or K-ras mutations in canine melanomas. To elucidate whether ras mutations exist in these naturally occurring tumours in dogs, in the present study we screened 13 canine fibrosarcomas, 2 feline fibrosarcomas and 11 canine melanomas for point mutations, particularly within the mutational hot-spots, making this the first study to investigate a large number of canine fibrosarcomas. None of the samples showed a K- or N-ras hot spot mutation. Thus, our data strongly suggest that ras mutations at the hot-spot loci are very rare and do not play a major role in the pathogenesis of the spontaneously occurring canine tumours investigated.

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

PubMed

Agrawal, Neeraj J; Helk, Bernhard; Trout, Bernhardt L

2014-01-21

Identifying hot-spot residues - residues that are critical to protein-protein binding - can help to elucidate a protein's function and assist in designing therapeutic molecules to target those residues. We present a novel computational tool, termed spatial-interaction-map (SIM), to predict the hot-spot residues of an evolutionarily conserved protein-protein interaction from the structure of an unbound protein alone. SIM can predict the protein hot-spot residues with an accuracy of 36-57%. Thus, the SIM tool can be used to predict the yet unknown hot-spot residues for many proteins for which the structure of the protein-protein complexes are not available, thereby providing a clue to their functions and an opportunity to design therapeutic molecules to target these proteins. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

The thermal emission spectrum of Io and a determination of the heat flux from its hot spots

NASA Technical Reports Server (NTRS)

Sinton, W. M.

1981-01-01

Observations of thermal emission from Io in the near infrared made during an eclipse were combined with unpublished 8- to 13-micron intermediate band photometry and a 16- to 22-micron spectrum to specify Io's emission spectrum from 2.2 to 22 microns. Models were calculated having 'hot spots' at several different temperatures superposed on a surface, the major part of which is assumed to be at the solar equilibrium temperature. It was possible to fit the entire composite spectrum with this model. It is argued that the total emission from the hot spots can be equated to the nonsolar energy input into Io. The disk-averaged heat radiated by the hot spots is found to be 180 + or 60 microwatts/sq cm = 43 + or - 14 microcalories/sq cm-sec. A possible bimodal temperature distribution of the hot spots is discussed.

Volcanic hot spots on Io - Correlation with low-albedo calderas

NASA Technical Reports Server (NTRS)

Mcewen, A. S.; Soderblom, L. A.; Matson, D. L.; Johnson, T. V.

1985-01-01

In the present investigation, it is shown that a one-to-one correspondence exists on Io between hot spots and features with normal albedos less than or equal to 0.3 (in the Voyager orange filter). It is pointed out that the hot spots are a manifestation of the prolific volcanic activity and heat flow of Io, widely believed to be due to dissipation of tidal energy resulting from the forward eccentricity of Io's orbit and the tides raised by Jupiter. All of the hot spots identified by the Voyager 1 infrared interferometric spectrometer (IRIS) correspond to relatively low-albedo features. An approach has been developed to identify hot spots not included in the IRIS inventory and to model their temperatures. The spectral reflectivities of the low-albedo features, extracted from the multispectral mosaics produced by Soderblom et al. (1985), are also presented, and compared to the laboratory spectra of a variety of candidate materials.

Kinematic Age Estimates for Four Compact Symmetric Objects from the Pearson-Readhead Survey

NASA Astrophysics Data System (ADS)

Taylor, G. B.; Marr, J. M.; Pearson, T. J.; Readhead, A. C. S.

2000-09-01

Based on multiepoch observations at 15 and 43 GHz with the Very Long Baseline Array (VLBA), we detect significant angular expansions between the two hot spots of four compact symmetric objects (CSOs). From these relative motions we derive kinematic ages of between 300 and 1200 yr for the radio emission. These ages lend support to the idea that CSOs are produced in a recent phase of activity. These observations also allow us to study the evolution of the hot spots dynamically in individual sources. In all four sources the hot spots are separating along the source axis, but in 1031+567 the tip of the hot spot appears to be moving almost orthogonally to the source axis. Jet components, seen in three of the four sources observed, are found to be moving relativistically outward from the central engines toward the more slowly moving hot spots.

Effects of Hot-Spot Geometry on Backscattering and Down-Scattering Neutron Spectra

NASA Astrophysics Data System (ADS)

Mohamed, Z. L.; Mannion, O. M.; Forrest, C. J.; Knauer, J. P.; Anderson, K. S.; Radha, P. B.

2017-10-01

The measured neutron spectrum produced by a fusion experiment plays a key role in inferring observable quantities. One important observable is the areal density of an implosion, which is inferred by measuring the scattering of neutrons. This project seeks to use particle-transport simulations to model the effects of hot-spot geometry on backscattering and down-scattering neutron spectra along different lines of sight. Implosions similar to those conducted at the Laboratory of Laser Energetics are modeled by neutron transport through a DT plasma and a DT ice shell using the particle transport codes MCNP and IRIS. Effects of hot-spot geometry are obtained by ``detecting'' scattered neutrons along different lines of sight. This process is repeated for various hot-spot geometries representing known shape distortions between the hot spot and the shell. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Protein protein interactions: organization, cooperativity and mapping in a bottom-up Systems Biology approach

NASA Astrophysics Data System (ADS)

Keskin, Ozlem; Ma, Buyong; Rogale, Kristina; Gunasekaran, K.; Nussinov, Ruth

2005-06-01

Understanding and ultimately predicting protein associations is immensely important for functional genomics and drug design. Here, we propose that binding sites have preferred organizations. First, the hot spots cluster within densely packed 'hot regions'. Within these regions, they form networks of interactions. Thus, hot spots located within a hot region contribute cooperatively to the stability of the complex. However, the contributions of separate, independent hot regions are additive. Moreover, hot spots are often already pre-organized in the unbound (free) protein states. Describing a binding site through independent local hot regions has implications for binding site definition, design and parametrization for prediction. The compactness and cooperativity emphasize the similarity between binding and folding. This proposition is grounded in computation and experiment. It explains why summation of the interactions may over-estimate the stability of the complex. Furthermore, statistically, charge-charge coupling of the hot spots is disfavored. However, since within the highly packed regions the solvent is screened, the electrostatic contributions are strengthened. Thus, we propose a new description of protein binding sites: a site consists of (one or a few) self-contained cooperative regions. Since the residue hot spots are those conserved by evolution, proteins binding multiple partners at the same sites are expected to use all or some combination of these regions.

Protein binding hot spots prediction from sequence only by a new ensemble learning method.

PubMed

Hu, Shan-Shan; Chen, Peng; Wang, Bing; Li, Jinyan

2017-10-01

Hot spots are interfacial core areas of binding proteins, which have been applied as targets in drug design. Experimental methods are costly in both time and expense to locate hot spot areas. Recently, in-silicon computational methods have been widely used for hot spot prediction through sequence or structure characterization. As the structural information of proteins is not always solved, and thus hot spot identification from amino acid sequences only is more useful for real-life applications. This work proposes a new sequence-based model that combines physicochemical features with the relative accessible surface area of amino acid sequences for hot spot prediction. The model consists of 83 classifiers involving the IBk (Instance-based k means) algorithm, where instances are encoded by important properties extracted from a total of 544 properties in the AAindex1 (Amino Acid Index) database. Then top-performance classifiers are selected to form an ensemble by a majority voting technique. The ensemble classifier outperforms the state-of-the-art computational methods, yielding an F1 score of 0.80 on the benchmark binding interface database (BID) test set. http://www2.ahu.edu.cn/pchen/web/HotspotEC.htm .

Functional Roles of Acetylated Histone Marks at Mouse Meiotic Recombination Hot Spots

PubMed Central

Wu, Zhen; Fallahi, Mohammad; Ouizem, Souad; Liu, Qin; Li, Weimin; Costi, Roberta; Roush, William R.; Bois, Philippe R. J.

2016-01-01

ABSTRACT Meiotic recombination initiates following the formation of DNA double-strand breaks (DSBs) by the Spo11 endonuclease early in prophase I, at discrete regions in the genome coined “hot spots.” In mammals, meiotic DSB site selection is directed in part by sequence-specific binding of PRDM9, a polymorphic histone H3 (H3K4Me3) methyltransferase. However, other chromatin features needed for meiotic hot spot specification are largely unknown. Here we show that the recombinogenic cores of active hot spots in mice harbor several histone H3 and H4 acetylation and methylation marks that are typical of open, active chromatin. Further, deposition of these open chromatin-associated histone marks is dynamic and is manifest at spermatogonia and/or pre-leptotene-stage cells, which facilitates PRDM9 binding and access for Spo11 to direct the formation of DSBs, which are initiated at the leptotene stage. Importantly, manipulating histone acetylase and deacetylase activities established that histone acetylation marks are necessary for both hot spot activity and crossover resolution. We conclude that there are functional roles for histone acetylation marks at mammalian meiotic recombination hot spots. PMID:27821479

Hot spot heat transfer - Its application to Venus and implications to Venus and earth

NASA Technical Reports Server (NTRS)

Morgan, P.; Phillips, R. J.

1983-01-01

Using a model that gives a relationship between surface elevation, lithospheric thickness, and heat flux, the hot spot heat loss mechanism is tested for Venus. The mechanism is found to readily explain the predicted heat loss of the planet with a modest number of hot spots (of the order of 35). Lithospheric thickness variations can explain approximately 93 percent of the mapped topography of Venus. Above a radius of 6053 km, additional compensation is required, and this can be effected by incorporating a variable thickness crust into the model. If it is assumed that the crust is generated on the crests of the hot spots, probably by processes associated with volcanism, the model is consistent with nearly 99 percent of the mapped topography of Venus. In addition, the model is basically consistent with available gravity data and interpretations that suggest compensated topography and great depths of compensation (100-1000 km) for the midlatitudes of the planet. It is thought that the approximately 1 percent of the topography not explained by hot spot crustal generation is compensated at a shallower depth primarily by variations in crustal thickness that are not directly related to hot spot volcanism.

Hot spot dynamics in carbon nanotube array devices.

PubMed

Engel, Michael; Steiner, Mathias; Seo, Jung-Woo T; Hersam, Mark C; Avouris, Phaedon

2015-03-11

We report on the dynamics of spatial temperature distributions in aligned semiconducting carbon nanotube array devices with submicrometer channel lengths. By using high-resolution optical microscopy in combination with electrical transport measurements, we observe under steady state bias conditions the emergence of time-variable, local temperature maxima with dimensions below 300 nm, and temperatures above 400 K. On the basis of time domain cross-correlation analysis, we investigate how the intensity fluctuations of the thermal radiation patterns are correlated with the overall device current. The analysis reveals the interdependence of electrical current fluctuations and time-variable hot spot formation that limits the overall device performance and, ultimately, may cause device degradation. The findings have implications for the future development of carbon nanotube-based technologies.

Rocket engine hot-spot detector

NASA Astrophysics Data System (ADS)

Collamore, F. N.

1985-04-01

On high performance devices such as rocket engines it is desirable to know if local hot spots or areas of reduced cooling margin exist. The objective of this program is to design, fabricate and test an electronic hot spot detector capable of sensing local hot spot on the exterior circumference of a regeneratively cooled combustion chamber in order to avoid hardware damage. The electronic hot spot sensor consists of an array of 120 thermocouple elements which are bonded in a flexible belt of polyimide film. The design temperature range is from +30 F to +400 F continuously with an intermittent temperature of 500 F maximum. The thermocouple belt consists of 120 equally spaced copper-Constantan thermocouple junctions which is wrapped around the OMS liquid rocket engine combustion chamber, to monitor temperatures of individual cooling channels. Each thermocouple is located over a cooling channel near the injector end of the combustion chamber. The thermocouple array sensor is held in place by a spring loaded clamp band. Analyses show that in the event of a blocked cooling channel the surface temperature of the chamber over the blocked channel will rise from a normal operating temperature of approx. 300 F to approx. 600 F. The hot spot detector will respond quickly to this change with a response time constant less than 0.05 seconds. The hot spot sensor assembly is fabricated with a laminated construction of layers of Kapton film and an outer protective layer of fiberglass reinforced silicone rubber.

Simultaneous diagnosis of radial profiles and mix in NIF ignition-scale implosions via X-ray spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciricosta, O.; Scott, H.; Durey, P.

In a National Ignition Facility implosion, hydrodynamic instabilities may cause the cold material from the imploding shell to be injected into the hot-spot (hot-spot mix), enhancing the radiative and conductive losses, which in turn may lead to a quenching of the ignition process. The bound-bound features of the spectrum emitted by high-Z ablator dopants that get mixed into the hot-spot have been previously used to infer the total amount of mixed mass; however, the typical errorbars are larger than the maximum tolerable mix. We present in this paper an improved 2D model for mix spectroscopy which can be used tomore » retrieve information on both the amount of mixed mass and the full imploded plasma profile. By performing radiation transfer and simultaneously fitting all of the features exhibited by the spectra, we are able to constrain self-consistently the effect of the opacity of the external layers of the target on the emission, thus improving the accuracy of the inferred mixed mass. The model's predictive capabilities are first validated by fitting simulated spectra arising from fully characterized hydrodynamic simulations, and then, the model is applied to previously published experimental results, providing values of mix mass in agreement with previous estimates. Finally, we show that the new self consistent procedure leads to better constrained estimates of mix and also provides insight into the sensitivity of the hot-spot spectroscopy to the spatial properties of the imploded capsule, such as the in-flight aspect ratio of the cold fuel surrounding the hotspot.« less

Lung Hot Spot Without Corresponding Computed Tomography Abnormality on Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: Artifactual or Real, Iatrogenic or Pathologic?

PubMed

Liu, Yiyan

Focal lung uptake without corresponding lesions or abnormalities on computed tomography (CT) scan poses a dilemma in the interpretation of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT). A limited number of case reports have previously suggested an artifactual or iatrogenic nature of the uptake. In the present study, 8 relevant cases were included within a retrospective search of the database. Medical records were reviewed for follow-up radiological and pathologic information. In 7 of 8 cases with focal increased FDG uptake but no corresponding lesions or abnormalities on CT scan, the lung hot spots were artifactual or iatrogenic upon follow-up diagnostic chest CT or repeated PET/CT or both the scans. Microemboli were most likely a potential cause of the pulmonary uptake, with or without partial paravenous injection. One case in the series had a real pulmonary lesion demonstrated on follow-up PET/CT scans and on surgical pathology, although the initial integrated CT and follow-up diagnostic chest CT scans revealed negative findings to demonstrate pulmonary abnormalities corresponding to the hot spot on the PET scan. In conclusion, the finding of a lung hot spot in the absence of anatomical abnormality on FDG PET/CT was most likely artifactual or iatrogenic, but it might also represent a real pulmonary lesion. Nonvisualization of anatomical abnormality could be because of its small size and position directly overlying a segmental vessel. Further image follow-up is necessary and important to clarify the nature of the uptake. Copyright © 2017 Elsevier Inc. All rights reserved.

Simultaneous diagnosis of radial profiles and mix in NIF ignition-scale implosions via X-ray spectroscopy

DOE PAGES

Ciricosta, O.; Scott, H.; Durey, P.; ...

2017-11-06

In a National Ignition Facility implosion, hydrodynamic instabilities may cause the cold material from the imploding shell to be injected into the hot-spot (hot-spot mix), enhancing the radiative and conductive losses, which in turn may lead to a quenching of the ignition process. The bound-bound features of the spectrum emitted by high-Z ablator dopants that get mixed into the hot-spot have been previously used to infer the total amount of mixed mass; however, the typical errorbars are larger than the maximum tolerable mix. We present in this paper an improved 2D model for mix spectroscopy which can be used tomore » retrieve information on both the amount of mixed mass and the full imploded plasma profile. By performing radiation transfer and simultaneously fitting all of the features exhibited by the spectra, we are able to constrain self-consistently the effect of the opacity of the external layers of the target on the emission, thus improving the accuracy of the inferred mixed mass. The model's predictive capabilities are first validated by fitting simulated spectra arising from fully characterized hydrodynamic simulations, and then, the model is applied to previously published experimental results, providing values of mix mass in agreement with previous estimates. Finally, we show that the new self consistent procedure leads to better constrained estimates of mix and also provides insight into the sensitivity of the hot-spot spectroscopy to the spatial properties of the imploded capsule, such as the in-flight aspect ratio of the cold fuel surrounding the hotspot.« less

Simultaneous diagnosis of radial profiles and mix in NIF ignition-scale implosions via X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Ciricosta, O.; Scott, H.; Durey, P.; Hammel, B. A.; Epstein, R.; Preston, T. R.; Regan, S. P.; Vinko, S. M.; Woolsey, N. C.; Wark, J. S.

2017-11-01

In a National Ignition Facility implosion, hydrodynamic instabilities may cause the cold material from the imploding shell to be injected into the hot-spot (hot-spot mix), enhancing the radiative and conductive losses, which in turn may lead to a quenching of the ignition process. The bound-bound features of the spectrum emitted by high-Z ablator dopants that get mixed into the hot-spot have been previously used to infer the total amount of mixed mass; however, the typical errorbars are larger than the maximum tolerable mix. We present here an improved 2D model for mix spectroscopy which can be used to retrieve information on both the amount of mixed mass and the full imploded plasma profile. By performing radiation transfer and simultaneously fitting all of the features exhibited by the spectra, we are able to constrain self-consistently the effect of the opacity of the external layers of the target on the emission, thus improving the accuracy of the inferred mixed mass. The model's predictive capabilities are first validated by fitting simulated spectra arising from fully characterized hydrodynamic simulations, and then, the model is applied to previously published experimental results, providing values of mix mass in agreement with previous estimates. We show that the new self consistent procedure leads to better constrained estimates of mix and also provides insight into the sensitivity of the hot-spot spectroscopy to the spatial properties of the imploded capsule, such as the in-flight aspect ratio of the cold fuel surrounding the hotspot.

40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

Code of Federal Regulations, 2011 CFR

2011-07-01

... (“Localized CO, PM10, and PM2.5 violations”) must be based on quantitative analysis using the applicable air... § 93.116 may be based on either: (i) Quantitative methods that represent reasonable and common... hot-spot analyses. (1) The hot-spot demonstration required by § 93.116 must be based on quantitative...

40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

Code of Federal Regulations, 2013 CFR

2013-07-01

... (“Localized CO, PM10, and PM2.5 violations”) must be based on quantitative analysis using the applicable air... § 93.116 may be based on either: (i) Quantitative methods that represent reasonable and common... hot-spot analyses. (1) The hot-spot demonstration required by § 93.116 must be based on quantitative...

40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

Code of Federal Regulations, 2012 CFR

2012-07-01

... (“Localized CO, PM10, and PM2.5 violations”) must be based on quantitative analysis using the applicable air... § 93.116 may be based on either: (i) Quantitative methods that represent reasonable and common... hot-spot analyses. (1) The hot-spot demonstration required by § 93.116 must be based on quantitative...

40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

Code of Federal Regulations, 2010 CFR

2010-07-01

... (“Localized CO, PM10, and PM2.5 violations”) must be based on quantitative analysis using the applicable air... § 93.116 may be based on either: (i) Quantitative methods that represent reasonable and common... hot-spot analyses. (1) The hot-spot demonstration required by § 93.116 must be based on quantitative...

Searching for biogeochemical hot spots in three dimensions: soil C and N cycling in hydropedologic settings in a northern hardwood forest

Treesearch

J.L. Morse; S.F. Werner; C.P. Gillin; C.L. Goodale; S.W. Bailey; K.J. McGuire; P.M. Groffman

2014-01-01

Understanding and predicting the extent, location, and function of biogeochemical hot spots at the watershed scale is a frontier in environmental science. We applied a hydropedologic approach to identify (1) biogeochemical differences among morphologically distinct hydropedologic settings and (2) hot spots of microbial carbon (C) and nitrogen (N) cycling activity in a...

Content-based analysis of Ki-67 stained meningioma specimens for automatic hot-spot selection.

PubMed

Swiderska-Chadaj, Zaneta; Markiewicz, Tomasz; Grala, Bartlomiej; Lorent, Malgorzata

2016-10-07

Hot-spot based examination of immunohistochemically stained histological specimens is one of the most important procedures in pathomorphological practice. The development of image acquisition equipment and computational units allows for the automation of this process. Moreover, a lot of possible technical problems occur in everyday histological material, which increases the complexity of the problem. Thus, a full context-based analysis of histological specimens is also needed in the quantification of immunohistochemically stained specimens. One of the most important reactions is the Ki-67 proliferation marker in meningiomas, the most frequent intracranial tumour. The aim of our study is to propose a context-based analysis of Ki-67 stained specimens of meningiomas for automatic selection of hot-spots. The proposed solution is based on textural analysis, mathematical morphology, feature ranking and classification, as well as on the proposed hot-spot gradual extinction algorithm to allow for the proper detection of a set of hot-spot fields. The designed whole slide image processing scheme eliminates such artifacts as hemorrhages, folds or stained vessels from the region of interest. To validate automatic results, a set of 104 meningioma specimens were selected and twenty hot-spots inside them were identified independently by two experts. The Spearman rho correlation coefficient was used to compare the results which were also analyzed with the help of a Bland-Altman plot. The results show that most of the cases (84) were automatically examined properly with two fields of view with a technical problem at the very most. Next, 13 had three such fields, and only seven specimens did not meet the requirement for the automatic examination. Generally, the Automatic System identifies hot-spot areas, especially their maximum points, better. Analysis of the results confirms the very high concordance between an automatic Ki-67 examination and the expert's results, with a Spearman rho higher than 0.95. The proposed hot-spot selection algorithm with an extended context-based analysis of whole slide images and hot-spot gradual extinction algorithm provides an efficient tool for simulation of a manual examination. The presented results have confirmed that the automatic examination of Ki-67 in meningiomas could be introduced in the near future.

Persistence of forage fish ‘hot spots’ and its association with foraging Steller sea lions (Eumetopias jubatus) in southeast Alaska

NASA Astrophysics Data System (ADS)

Gende, Scott M.; Sigler, Michael F.

2006-02-01

Whereas primary and secondary productivity at oceanic 'hotspots' may be a function of upwelling and temperature fronts, the aggregation of higher-order vertebrates is a function of their ability to search for and locate these areas. Thus, understanding how predators aggregate at these productive foraging areas is germane to the study of oceanic hot spots. We examined the spatial distribution of forage fish in southeast Alaska for three years to better understand Steller sea lion ( Eumetopias jubatus) aggregations and foraging behavior. Energy densities (millions KJ/km 2) of forage fish were orders of magnitude greater during the winter months (November-February), due to the presence of schools of overwintering Pacific herring ( Clupea pallasi). Within the winter months, herring consistently aggregated at a few areas, and these areas persisted throughout the season and among years. Thus, our study area was characterized by seasonally variable, highly abundant but highly patchily distributed forage fish hot spots. More importantly, the persistence of these forage fish hot spots was an important characteristic in determining whether foraging sea lions utilized them. Over 40% of the variation in the distribution of sea lions on our surveys was explained by the persistence of forage fish hot spots. Using a simple spatial model, we demonstrate that when the density of these hot spots is low, effort necessary to locate these spots is minimized when those spots persist through time. In contrast, under similar prey densities but lower persistence, effort increases dramatically. Thus an important characteristic of pelagic hot spots is their persistence, allowing predators to predict their locations and concentrate search efforts accordingly.

Tuning temperature and size of hot spots and hot-spot arrays.

PubMed

Saïdi, Elika; Babinet, Nicolas; Lalouat, Loïc; Lesueur, Jérôme; Aigouy, Lionel; Volz, Sébastian; Labéguerie-Egéa, Jessica; Mortier, Michel

2011-01-17

By using scanning thermal microscopy, it is shown that nanoscale constrictions in metallic microwires deposited on an oxidized silicon substrate can be tuned in terms of temperature and confinement size. High-resolution temperature maps indeed show that submicrometer hot spots and hot-spot arrays are obtained when the SiO(2) layer thickness decreases below 100 nm. When the SiO(2) thickness becomes larger, heat is less confined in the vicinity of the constrictions and laterally spreads all along the microwire. These results are in good agreement with numerical simulations, which provide dependences between silica-layer thickness and nanodot shape and temperature. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

KFC2: a knowledge-based hot spot prediction method based on interface solvation, atomic density, and plasticity features.

PubMed

Zhu, Xiaolei; Mitchell, Julie C

2011-09-01

Hot spots constitute a small fraction of protein-protein interface residues, yet they account for a large fraction of the binding affinity. Based on our previous method (KFC), we present two new methods (KFC2a and KFC2b) that outperform other methods at hot spot prediction. A number of improvements were made in developing these new methods. First, we created a training data set that contained a similar number of hot spot and non-hot spot residues. In addition, we generated 47 different features, and different numbers of features were used to train the models to avoid over-fitting. Finally, two feature combinations were selected: One (used in KFC2a) is composed of eight features that are mainly related to solvent accessible surface area and local plasticity; the other (KFC2b) is composed of seven features, only two of which are identical to those used in KFC2a. The two models were built using support vector machines (SVM). The two KFC2 models were then tested on a mixed independent test set, and compared with other methods such as Robetta, FOLDEF, HotPoint, MINERVA, and KFC. KFC2a showed the highest predictive accuracy for hot spot residues (True Positive Rate: TPR = 0.85); however, the false positive rate was somewhat higher than for other models. KFC2b showed the best predictive accuracy for hot spot residues (True Positive Rate: TPR = 0.62) among all methods other than KFC2a, and the False Positive Rate (FPR = 0.15) was comparable with other highly predictive methods. Copyright © 2011 Wiley-Liss, Inc.

Preliminary results on the composition of Jupiter's troposphere in hot spot regions from the JIRAM/Juno instrument

NASA Astrophysics Data System (ADS)

Grassi, D.; Adriani, A.; Mura, A.; Dinelli, B. M.; Sindoni, G.; Turrini, D.; Filacchione, G.; Migliorini, A.; Moriconi, M. L.; Tosi, F.; Noschese, R.; Cicchetti, A.; Altieri, F.; Fabiano, F.; Piccioni, G.; Stefani, S.; Atreya, S.; Lunine, J.; Orton, G.; Ingersoll, A.; Bolton, S.; Levin, S.; Connerney, J.; Olivieri, A.; Amoroso, M.

2017-05-01

The Jupiter InfraRed Auroral Mapper (JIRAM) instrument on board the Juno spacecraft performed observations of two bright Jupiter hot spots around the time of the first Juno pericenter passage on 27 August 2016. The spectra acquired in the 4-5 µm spectral range were analyzed to infer the residual opacities of the uppermost cloud deck as well as the mean mixing ratios of water, ammonia, and phosphine at the approximate level of few bars. Our results support the current view of hot spots as regions of prevailing descending vertical motions in the atmosphere but extend this view suggesting that upwelling may occur at the southern boundaries of these structures. Comparison with the global ammonia abundance measured by Juno Microwave Radiometer suggests also that hot spots may represent sites of local enrichment of this gas. JIRAM also identifies similar spatial patterns in water and phosphine contents in the two hot spots.

A study of the long-term properties of Jovian hot spots from HST and ground-based observations between 1994 and 1998

NASA Astrophysics Data System (ADS)

Arregui, E.; Rojas, J. F.; Sanchez-Lavega, A.; Lecacheux, J.; Colas, F.; Miyazaki, I.; Parker, D.

2000-10-01

We have used the HST-WFPC2 archived images of Jupiter in the period 1994-1998 together with a large set of CCD ground based images, to study the zonal distribution, long-term motions, lifetimes, interactions and other properties of the hot spot - plume regions at 7 degrees North. Red and near infrared filters covering the wavelength range 650 - 953 nm have been used since they show the hot spots with a high contrast. We have found that the hot spots have velocities ranging from 95 to 112 m/s and are grouped typically in families of three to six members. We do not found any correlation between their velocity and wavenumber. The long-term survey allowed us to identify mergers and splitting of the hot spots areas. The Spanish team was supported by Gobierno Vasco PI 034/97. The French team was supported by the "Programme National de Planetologie."

Tunable subwavelength hot spot of dipole nanostructure based on VO2 phase transition.

PubMed

Park, Jun-Bum; Lee, Il-Min; Lee, Seung-Yeol; Kim, Kyuho; Choi, Dawoon; Song, Eui Young; Lee, Byoungho

2013-07-01

We propose a novel approach to generate and tune a hot spot in a dipole nanostructure of vanadium dioxide (VO2) laid on a gold (Au) substrate. By inducing a phase transition of the VO2, the spatial and spectral distributions of the hot spot generated in the feed gap of the dipole can be tuned. Our numerical simulation based on a finite-element method shows a strong intensity enhancement difference and tunability near the wavelength of 678 nm, where the hot spot shows 172-fold intensity enhancement when VO2 is in the semiconductor phase. The physical mechanisms of forming the hot spots at the two-different phases are discussed. Based on our analysis, the effects of geometric parameters in our dipole structure are investigated with an aim of enhancing the intensity and the tunability. We hope that the proposed nanostructure opens up a practical approach for the tunable near-field nano-photonic devices.

Controlling surface-plasmon-polaritons launching with hot spot cylindrical waves in a metallic slit structure.

PubMed

Yao, Wenjie; Sun, Chengwei; Gong, Qihuang; Chen, Jianjun

2016-09-23

Plasmonic nanostructures, which are used to generate surface plasmon polaritons (SPPs), always involve sharp corners where the charges can accumulate. This can result in strong localized electromagnetic fields at the metallic corners, forming the hot spots. The influence of the hot spots on the propagating SPPs are investigated theoretically and experimentally in a metallic slit structure. It is found that the electromagnetic fields radiated from the hot spots, termed as the hot spot cylindrical wave (HSCW), can greatly manipulate the SPP launching in the slit structure. The physical mechanism behind the manipulation of the SPP launching with the HSCW is explicated by a semi-analytic model. By using the HSCW, unidirectional SPP launching is experimentally realized in an ultra-small metallic step-slit structure. The HSCW bridges the localized surface plasmons and the propagating surface plasmons in an integrated platform and thus may pave a new route to the design of plasmonic devices and circuits.

Finite volume analysis of temperature effects induced by active MRI implants: 2. Defects on active MRI implants causing hot spots.

PubMed

Busch, Martin H J; Vollmann, Wolfgang; Grönemeyer, Dietrich H W

2006-05-26

Active magnetic resonance imaging implants, for example stents, stent grafts or vena cava filters, are constructed as wireless inductively coupled transmit and receive coils. They are built as a resonator tuned to the Larmor frequency of a magnetic resonance system. The resonator can be added to or incorporated within the implant. This technology can counteract the shielding caused by eddy currents inside the metallic implant structure. This may allow getting diagnostic information of the implant lumen (in stent stenosis or thrombosis for example). The electro magnetic rf-pulses during magnetic resonance imaging induce a current in the circuit path of the resonator. A by material fatigue provoked partial rupture of the circuit path or a broken wire with touching surfaces can set up a relatively high resistance on a very short distance, which may behave as a point-like power source, a hot spot, inside the body part the resonator is implanted to. This local power loss inside a small volume can reach (1/4) of the total power loss of the intact resonating circuit, which itself is proportional to the product of the resonator volume and the quality factor and depends as well from the orientation of the resonator with respect to the main magnetic field and the imaging sequence the resonator is exposed to. First an analytical solution of a hot spot for thermal equilibrium is described. This analytical solution with a definite hot spot power loss represents the worst case scenario for thermal equilibrium inside a homogeneous medium without cooling effects. Starting with this worst case assumptions additional conditions are considered in a numerical simulation, which are more realistic and may make the results less critical. The analytical solution as well as the numerical simulations use the experimental experience of the maximum hot spot power loss of implanted resonators with a definite volume during magnetic resonance imaging investigations. The finite volume analysis calculates the time developing temperature maps for the model of a broken linear metallic wire embedded in tissue. Half of the total hot spot power loss is assumed to diffuse into both wire parts at the location of a defect. The energy is distributed from there by heat conduction. Additionally the effect of blood perfusion and blood flow is respected in some simulations because the simultaneous appearance of all worst case conditions, especially the absence of blood perfusion and blood flow near the hot spot, is very unlikely for vessel implants. The analytical solution as worst case scenario as well as the finite volume analysis for near worst case situations show not negligible volumes with critical temperature increases for part of the modeled hot spot situations. MR investigations with a high rf-pulse density lasting below a minute can establish volumes of several cubic millimeters with temperature increases high enough to start cell destruction. Longer exposure times can involve volumes larger than 100 mm3. Even temperature increases in the range of thermal ablation are reached for substantial volumes. MR sequence exposure time and hot spot power loss are the primary factors influencing the volume with critical temperature increases. Wire radius, wire material as well as the physiological parameters blood perfusion and blood flow inside larger vessels reduce the volume with critical temperature increases, but do not exclude a volume with critical tissue heating for resonators with a large product of resonator volume and quality factor. The worst case scenario assumes thermal equilibrium for a hot spot embedded in homogeneous tissue without any cooling due to blood perfusion or flow. The finite volume analysis can calculate the results for near and not close to worst case conditions. For both cases a substantial volume can reach a critical temperature increase in a short time. The analytical solution, as absolute worst case, points out that resonators with a small product of inductance volume and quality factor (Q V(ind) < 2 cm3) are definitely save. Stents for coronary vessels or resonators used as tracking devices for interventional procedures therefore have no risk of high temperature increases. The finite volume analysis shows for sure that also conditions not close to the worst case reach physiologically critical temperature increases for implants with a large product of inductance volume and quality factor (Q V(ind) > 10 cm3). Such resonators exclude patients from exactly the MRI investigation these devices are made for.

Finite volume analysis of temperature effects induced by active MRI implants: 2. Defects on active MRI implants causing hot spots

PubMed Central

Busch, Martin HJ; Vollmann, Wolfgang; Grönemeyer, Dietrich HW

2006-01-01

Background Active magnetic resonance imaging implants, for example stents, stent grafts or vena cava filters, are constructed as wireless inductively coupled transmit and receive coils. They are built as a resonator tuned to the Larmor frequency of a magnetic resonance system. The resonator can be added to or incorporated within the implant. This technology can counteract the shielding caused by eddy currents inside the metallic implant structure. This may allow getting diagnostic information of the implant lumen (in stent stenosis or thrombosis for example). The electro magnetic rf-pulses during magnetic resonance imaging induce a current in the circuit path of the resonator. A by material fatigue provoked partial rupture of the circuit path or a broken wire with touching surfaces can set up a relatively high resistance on a very short distance, which may behave as a point-like power source, a hot spot, inside the body part the resonator is implanted to. This local power loss inside a small volume can reach ¼ of the total power loss of the intact resonating circuit, which itself is proportional to the product of the resonator volume and the quality factor and depends as well from the orientation of the resonator with respect to the main magnetic field and the imaging sequence the resonator is exposed to. Methods First an analytical solution of a hot spot for thermal equilibrium is described. This analytical solution with a definite hot spot power loss represents the worst case scenario for thermal equilibrium inside a homogeneous medium without cooling effects. Starting with this worst case assumptions additional conditions are considered in a numerical simulation, which are more realistic and may make the results less critical. The analytical solution as well as the numerical simulations use the experimental experience of the maximum hot spot power loss of implanted resonators with a definite volume during magnetic resonance imaging investigations. The finite volume analysis calculates the time developing temperature maps for the model of a broken linear metallic wire embedded in tissue. Half of the total hot spot power loss is assumed to diffuse into both wire parts at the location of a defect. The energy is distributed from there by heat conduction. Additionally the effect of blood perfusion and blood flow is respected in some simulations because the simultaneous appearance of all worst case conditions, especially the absence of blood perfusion and blood flow near the hot spot, is very unlikely for vessel implants. Results The analytical solution as worst case scenario as well as the finite volume analysis for near worst case situations show not negligible volumes with critical temperature increases for part of the modeled hot spot situations. MR investigations with a high rf-pulse density lasting below a minute can establish volumes of several cubic millimeters with temperature increases high enough to start cell destruction. Longer exposure times can involve volumes larger than 100 mm3. Even temperature increases in the range of thermal ablation are reached for substantial volumes. MR sequence exposure time and hot spot power loss are the primary factors influencing the volume with critical temperature increases. Wire radius, wire material as well as the physiological parameters blood perfusion and blood flow inside larger vessels reduce the volume with critical temperature increases, but do not exclude a volume with critical tissue heating for resonators with a large product of resonator volume and quality factor. Conclusion The worst case scenario assumes thermal equilibrium for a hot spot embedded in homogeneous tissue without any cooling due to blood perfusion or flow. The finite volume analysis can calculate the results for near and not close to worst case conditions. For both cases a substantial volume can reach a critical temperature increase in a short time. The analytical solution, as absolute worst case, points out that resonators with a small product of inductance volume and quality factor (Q Vind < 2 cm3) are definitely save. Stents for coronary vessels or resonators used as tracking devices for interventional procedures therefore have no risk of high temperature increases. The finite volume analysis shows for sure that also conditions not close to the worst case reach physiologically critical temperature increases for implants with a large product of inductance volume and quality factor (Q Vind > 10 cm3). Such resonators exclude patients from exactly the MRI investigation these devices are made for. PMID:16729878

Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice

PubMed Central

de Boer, Esther; Jasin, Maria; Keeney, Scott

2015-01-01

Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency. PMID:26251527

Practice-Based Research: Ex Post Facto Evaluation of Evidence-Based Police Practices Implemented in Residential Burglary Micro-Time Hot Spots.

PubMed

Santos, Roberto G; Santos, Rachel Boba

2015-10-01

Police agencies around the country are implementing various strategies to reduce crime in their communities that need to be evaluated. These strategies are often based on systematic crime analysis and are focused on crime occurring in hot spots, which are areas of disproportionate amounts of crime. This article takes a practice-based research approach to evaluate whether evidence-based police strategies implemented by one police agency as its normal everyday crime reduction practice are effective in reducing residential burglary incidents in micro-time hot spots. A quasi-experimental ex post facto design is employed using 5 years of data from one police agency that has institutionalized the identification and response to micro-time hot spots into its day-to-day practices. Propensity score matching is used to match 54 pairs of micro-time hot spots using logistic regression to compute the propensity scores and greedy 1 to 1 matching with a caliper width of 0.5 of the standard deviation of the logit to match the cases. Independent t-tests show that tactical police response to micro-time hot spots can lead to significant reductions in residential burglary incidents without the spatial displacement of crime. Tactical police responses that seek to achieve short-term reductions in crime appear to be well suited for micro-time hot spots since they are, by nature, short term. Importantly, the conclusions are based on the evaluation of an agency's systematic implementation of the evidence-based practices as its normal practices and not for the sake of research. © The Author(s) 2015.

Ridge-crossing mantle plumes and gaps in tracks

NASA Astrophysics Data System (ADS)

Sleep, Norman H.

2002-12-01

Hot spot tracks approach, cross, and leave ridge axes. The complications of this process make it difficult to determine the track followed by a plume and the evolution of its vigor. When a plume is sufficiently near the ridge axis, buoyant plume material flows along the base of the lithosphere toward the axis, forming an on-axis hot spot. The track of the on-axis hot spot is a symmetric V on both plates and an unreliable indication of the path followed by the plume. Aseismic ridges form more or less along flowlines from a plume to a ridge axis when channels form at the base of the lithosphere. A dynamic effect is that off-axis hot spots appear to shut off at the time that an on-axis hot spot becomes active along an axis-approaching track. This produces a gap in the obvious track and a jump of the hot spot to the ridge axis. The gap results from the effects of ponded plume material on intraplate (membrane) stress. Membrane tension lets dikes ascend efficiently to produce obvious tracks of edifices. An off-axis hot spot shuts down when the plume is sufficiently near the ridge axis that plume material flows there, putting the nearby lithosphere above the plume into compression, preventing dikes. In addition, the off-axis thickness of plume material, which produces membrane tension, decreases as the slope of the base of the lithosphere increases beneath young lithosphere. Slow spreading rates favor gaps produced in this way. Gaps are observed near both fast and slow ridges.

The C-terminus hot spot region helps in the fibril formation of bacteriophage-associated hyaluronate lyase (HylP2).

PubMed

Shukla, Harish; Singh, Sudhir Kumar; Singh, Amit Kumar; Mitra, Kalyan; Akhtar, Md Sohail

2015-09-23

The bacteriophage encoded hyaluronate lyases (HylP and HylP2) degrade hyaluronan and other glycosaminoglycans. HylP2 forms a functional fibril under acidic conditions in which its N-terminus is proposed to form the fibrillar core, leading to nucleation and acceleration of fibril formation. Here we report the presence of a hot spot region (A144GVVVY149) towards the carboxy terminus of HylP2, essential for the acceleration of fibril formation. The 'hot spot' is observed to be inherently mutated for valines (A178AMVMY183) in case of HylP. The N- terminal swapped chimeras between these phage HLs ((N)HylP2(C)HylP and (N)HylP(C)HylP2) or HylP did not form fibrils at acidic pH. However, seeding of prefibrils of HylP2 recompensed nucleation and led to fibrillation in (N)HylP(C)HylP2. The V147A mutation in the 'hot spot' region abolished fibril formation in HylP2. The M179V and M181V double mutations in the 'hot spot' region of HylP led to fibrillation with the seeding of prefibrils. It appears that fibrillation in HylP2 even though is initiated by the N-terminus, is accelerated by the conserved 'hot spot' region in the C-terminus. A collagenous (Gly-X-Y)10 motif in the N-terminus and a mutated 'hot spot' region in the C-terminus of HylP affect fibrillar nucleation and acceleration respectively.

Jumping-droplet electronics hot-spot cooling

NASA Astrophysics Data System (ADS)

Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

2017-03-01

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

On the Solar Stimuli That Initiate Makkah Al Mukaramah, Al-Madinah Al-Munawarah And Jeddah Flash Floods

NASA Astrophysics Data System (ADS)

Elfaki, H.; Yousef, S.; Mawad, Ramy; Algafari, Y. H. O.; Amer, M.; Abdel-Sattar, W.

2017-12-01

Severe solar events manifested as highly energetic X-Ray events accompanied by coronal mass ejections ( CMEs) and proton flares caused flash floods in Makkah Al-Mukaramah, Al-Madinah Al-Munawarah and Jeddah. In the case of the 20 January 2005 CME that initiated severe flash on the 22 of January. it is shown that the CME lowered the pressure in the polar region and extended the low pressure regime to Saudi Arabia passing by the Mediterranean. Such passage accelerated evaporation and caused Cumulonimbus clouds to form and discharge flash floods over Makkah Al-Mukaramah. On the other hand, solar forcing due coronal holes have a different technique in initiating flash floods. The November 25 2009 and the 13-15 January 2011 Jeddah flash floods are attributed to prompt events due to fast solar streams emanated from two coronal holes that arrived the Earth on 24 November 2009 and 13 January 2011. We present evidences that those streams penetrated the Earth's magnetosphere and hit the troposphere at the western part of the Red Sea, dissipated their energy at 925mb geopotential height and left two hot spots. It follows that the air in the hot spots expanded and developed spots of low pressure air that spread over the Red Sea to its eastern coast. Accelerated evaporation due to reduced pressure caused quick formation of Cumulonimbus clouds that caused flash floods over Makkah Al-Mukaramah and Jeddah.

Coulomb explosion of “hot spot”

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oreshkin, V. I., E-mail: oreshkin@ovpe.hcei.tsc.ru; Tomsk Polytechnic University, Tomsk; Oreshkin, E. V.

The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulombmore » explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed, and the estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.« less

Hot Spot Detection System Using Landsat 8/OLI Data

NASA Astrophysics Data System (ADS)

Kato, S.; Nakamura, R.; Oda, A.; Iijima, A.; Kouyama, T.; Iwata, T.

2015-12-01

We developed a simple algorithm and a Web-based visualizing system to detect hot spots using Landsat 8 OLI multispectral data as one of the applications of the real-time processing of Landsat 8 data. An empirical equation and radiometric and reflective thresholds were derived to detect hot spots using the OLI data at band 5 (0.865 μm) and band 7 (2.200 μm) based on the increase in spectral radiance at shortwave infrared (SWIR) region due to the emission from objects with high surface temperature. We surveyed typical patterns of surface spectra using the ASTER spectral library to delineate a threshold to distinguish hot spots from background surfaces. To adjust the empirical coefficients of our detection algorithm, we visually inspected the detected hot spots using 6593 Landsat 8 scenes, which cover eastern part of East Asia, taken from January 1, 2014 to December 31, 2014, displayed on a dedicated Web GIS system. Eventually we determined threshold equations which can theoretically detect hot spots at temperatures above 230 °C over isothermal pixels and hot spots as small as 1 m2 at temperatures of 1000 °C as the lowest temperature and the smallest subpixel coverage, respectively, for daytime scenes. The algorithm detected hot spots including wildfires, volcanos, open burnings and factories. 30-m spatial resolution of Landsat 8 enabled to detect wild fires and open burnings accompanied by clearer shapes of fire front lines than MODIS and VIIRS fire products. Although the 16-day revisit cycle of Landsat 8 is too long to effectively find unexpected wildfire or outbreak of eruption, the revisit cycle is enough to monitor temporally stable heat sources, such as continually erupting volcanos and factories. False detection was found over building rooftops, which have relatively smooth surfaces at longer wavelengths, when specular reflection occurred at the satellite overpass.

Investigation of Hardness Change for Spot Welded Tailored Blank in Hot Stamping Using CCT and Deformation-CCT Diagrams

NASA Astrophysics Data System (ADS)

Yogo, Yasuhiro; Kurato, Nozomi; Iwata, Noritoshi

2018-04-01

When an outer panel of a B-pillar is manufactured with the hot stamping process, reinforcements are spot welded on its inner side. Before reinforcements are added, the microstructure of the outer panel is martensite. However, reheating during spot welding changes the martensite to ferrite, which has a lower hardness in the heat-affected zone than in other areas. If spot welding is conducted before hot stamping for making a spot welded tailored blank, the microstructure in the spot welded tailored blank after hot stamping is martensite. This sequence of processes avoids hardness reduction due to spot welding. In this study, the hardness and microstructure around spot welded parts of the tailored blank were investigated. The results clearly showed that areas close to the spot welded parts are severely stretched during hot stamping. In addition, stretching suppresses the martensitic phase transformation and reduces the hardness. To characterize this phenomenon, a simulation was conducted that considered the effects of pre-strain on the phase transformation. A continuous cooling transformation (CCT) diagram and a deformation continuous cooling transformation (DCCT) diagram were made in order to quantify the effect of the cooling rate and pre-strain on the phase transformation and hardness. The hardness was then calculated using the experimentally measured CCT and DCCT diagrams and the finite element analysis results. The calculated hardness was compared with the experimental hardness. Good agreement was found between the calculated and experimental results.

Investigation of Hardness Change for Spot Welded Tailored Blank in Hot Stamping Using CCT and Deformation-CCT Diagrams

NASA Astrophysics Data System (ADS)

Yogo, Yasuhiro; Kurato, Nozomi; Iwata, Noritoshi

2018-06-01

When an outer panel of a B-pillar is manufactured with the hot stamping process, reinforcements are spot welded on its inner side. Before reinforcements are added, the microstructure of the outer panel is martensite. However, reheating during spot welding changes the martensite to ferrite, which has a lower hardness in the heat-affected zone than in other areas. If spot welding is conducted before hot stamping for making a spot welded tailored blank, the microstructure in the spot welded tailored blank after hot stamping is martensite. This sequence of processes avoids hardness reduction due to spot welding. In this study, the hardness and microstructure around spot welded parts of the tailored blank were investigated. The results clearly showed that areas close to the spot welded parts are severely stretched during hot stamping. In addition, stretching suppresses the martensitic phase transformation and reduces the hardness. To characterize this phenomenon, a simulation was conducted that considered the effects of pre-strain on the phase transformation. A continuous cooling transformation (CCT) diagram and a deformation continuous cooling transformation (DCCT) diagram were made in order to quantify the effect of the cooling rate and pre-strain on the phase transformation and hardness. The hardness was then calculated using the experimentally measured CCT and DCCT diagrams and the finite element analysis results. The calculated hardness was compared with the experimental hardness. Good agreement was found between the calculated and experimental results.

Time variability of Io's volcanic activity from near-IR adaptive optics observations on 100 nights in 2013-2015

NASA Astrophysics Data System (ADS)

de Kleer, Katherine; de Pater, Imke

2016-12-01

Jupiter's moon Io is a dynamic target, exhibiting extreme and time-variable volcanic activity powered by tidal forcing from Jupiter. We have conducted a campaign of high-cadence observations of Io with the goal of characterizing its volcanic activity. Between Aug 2013 and the end of 2015, we imaged Io on 100 nights in the near-infrared with adaptive optics on the Keck and Gemini N telescopes, which resolve emission from individual volcanic hot spots. During our program, we made over 400 detections of 48 distinct hot spots, some of which were detected 30+ times. We use these observations to derive a timeline of global volcanic activity on Io, which exhibits wide variability from month to month. The timelines of thermal activity at individual volcanic centers have geophysical implications, and will permit future characterization by others. We evaluate hot spot detection limits and give a simple parameterization of the minimum detectable intensity as a function of emission angle, which can be applied to other analyses. We detected three outburst eruptions in August 2013, but no other outburst-scale events were observed in the subsequent ∼90 observations. Either the cluster of events in August 2013 was a rare occurrence, or there is a mechanism causing large events to occur closely-spaced in time. We also detected large eruptions (though not of outburst scale) within days of one another at Kurdalagon Patera and Sethlaus/Gabija Paterae in 2015. As was also seen in the Galileo dataset, the hot spots we detected can be separated into two categories based on their thermal emission: those that are persistently active for 1 year or more at moderate intensity, and those that are only briefly active, are time-variable, and often reach large intensities. A small number of hot spots in the latter category appear and subside in a matter of days, reaching particularly high intensities; although these are not bright enough to qualify as outbursts, their thermal signatures follow the same pattern, suggesting that a similar mechanism may be responsible for these events though at a smaller scale. Two eruptions seen at Kurdalagon Patera in January and April 2015 occurred simultaneously with a brightening of the neutral cloud and plasma torus which are sourced from Io's atmosphere. A plume at Kurdalagon Patera, such as was seen by New Horizons in 2007, could have been responsible for the influx of material that caused these brightenings.

Geostatistical risk estimation at waste disposal sites in the presence of hot spots.

PubMed

Komnitsas, Kostas; Modis, Kostas

2009-05-30

The present paper aims to estimate risk by using geostatistics at the wider coal mining/waste disposal site of Belkovskaya, Tula region, in Russia. In this area the presence of hot spots causes a spatial trend in the mean value of the random field and a non-Gaussian data distribution. Prior to application of geostatistics, subtraction of trend and appropriate smoothing and transformation of the data into a Gaussian form were carried out; risk maps were then generated for the wider study area in order to assess the probability of exceeding risk thresholds. Finally, the present paper discusses the need for homogenization of soil risk thresholds regarding hazardous elements that will enhance reliability of risk estimation and enable application of appropriate rehabilitation actions in contaminated areas.

An energy efficient multiple mobile sinks based routing algorithm for wireless sensor networks

NASA Astrophysics Data System (ADS)

Zhong, Peijun; Ruan, Feng

2018-03-01

With the fast development of wireless sensor networks (WSNs), more and more energy efficient routing algorithms have been proposed. However, one of the research challenges is how to alleviate the hot spot problem since nodes close to static sink (or base station) tend to die earlier than other sensors. The introduction of mobile sink node can effectively alleviate this problem since sink node can move along certain trajectories, causing hot spot nodes more evenly distributed. In this paper, we mainly study the energy efficient routing method with multiple mobile sinks support. We divide the whole network into several clusters and study the influence of mobile sink number on network lifetime. Simulation results show that the best network performance appears when mobile sink number is about 3 under our simulation environment.

Hot Spots and Mantle Plumes: A Window Into the Deep Earth and a Lesson on How Science Really Works

NASA Astrophysics Data System (ADS)

Caplan-Auerbach, J.

2010-12-01

Despite years of discussion, debate and controversy over the causes of ocean island volcanism, most students simply learn that such features form from fixed plumes of hot material rising from the core mantle boundary. Although we know that the Hawaiian plume exhibited substantial southward motion, most introductory geology textbooks still report that hot spots are fixed and that the Hawaiian-Emperor bend reflects a change in plate motion. That mantle plumes are the focus of significant controversy within the scientific community is rarely, if ever, discussed, and alternative models for the formation of intraplate volcanoes are ignored. Students may thus complete their studies without learning about the dynamic debate focused on the existence and formation of mantle plumes. This issue represents an opportunity for students to see how science really works, how new models are constructed, and what distinguishes a hypothesis from a theory. The culminating project in Western Washington University’s Introduction to Geophysics class, a course required for the BS degree in geology, focuses on the hot spot and mantle plume debate. For the first nine weeks of the quarter students learn about general topics in geophysics including plate tectonics, magnetism, seismology, gravity and heat flow. At the end of the course, students break into small research groups with the goal of investigating how geophysics may be used to address three questions: (1) Do ocean island volcanoes form from mantle plumes? (2) Are “hot spots” actually hot? (3) Are hot spots stationary? Each group examines how these questions may be addressed using a specific geophysical tool. In addition to the five topics described above, a sixth group investigates the question of “if not hot spots/mantle plumes, how do ocean island volcanoes form?” Students read the current literature on the topic and present their results to their classmates. Presentations focus on topics such as the use of seismic tomography to image deep plumes, the use of magnetic data to determine plume paleolatitude, and the search for heat flow anomalies near hot spots. On the final day of the class students revisit the three questions presented above and discuss whether their thoughts on the topic have changed as a result of studying the geophysics. Finally, the class discusses the issue in terms of Thomas Kuhn’s phases of scientific study, considering whether or not the mantle plumes paradigm is in crisis. As evidenced by comments in student course evaluations, the project is very popular and students appreciate the opportunity to investigate a modern scientific controversy. The project not only helps students learn how geophysics may be used to study the deep earth, it familiarizes them with current scientific literature, and perhaps most importantly, it allows them to learn about and engage in a critical scientific debate.

Global Distribution of Active Volcanism on Io as Known at the End of the Galileo Mission

NASA Technical Reports Server (NTRS)

Lopes, Rosaly M. C.; Kamp. Lucas W.; Smythe, W. D.; Radebaugh, J.; Turtle, E.; Perry, J.; Bruno, B.

2004-01-01

Hot spots are manifestations of Io s mechanism of internal heating and heat transfer. Therefore, the global distribution of hot spots and their power output has important implications for how Io is losing heat. The end of the Galileo mission is an opportune time to revisit studies of the distribution of hot spots on Io, and to investigate the distribution of their power output.

Hot-spot residues at the E9/Im9 interface help binding via different mechanisms.

PubMed

Wong, Sergio E; Baron, Riccardo; McCammon, J Andrew

2008-11-01

Protein-protein association involves many interface interactions, but they do not contribute equally. Ala scanning experiments reveal that only a few mutations significantly lower binding affinity. These key residues, which appear to drive protein-protein association, are called hot-spot residues. Molecular dynamics simulations of the Colicin E9/Im9 complex show Im9 Glu41 and Im9 Ser50, both hot-spots, bind via different mechanisms. The results suggest that Im9 Ser50 restricts Glu41 in a conformation auspicious for salt-bridge formation across the interface. This type of model may be helpful in engineering hot-spot clusters at protein-protein interfaces and, consequently, the design of specificity.

Lessons from hot spot analysis for fragment-based drug discovery

PubMed Central

Hall, David R.; Vajda, Sandor

2015-01-01

Analysis of binding energy hot spots at protein surfaces can provide crucial insights into the prospects for successful application of fragment-based drug discovery (FBDD), and whether a fragment hit can be advanced into a high affinity, druglike ligand. The key factor is the strength of the top ranking hot spot, and how well a given fragment complements it. We show that published data are sufficient to provide a sophisticated and quantitative understanding of how hot spots derive from protein three-dimensional structure, and how their strength, number and spatial arrangement govern the potential for a surface site to bind to fragment-sized and larger ligands. This improved understanding provides important guidance for the effective application of FBDD in drug discovery. PMID:26538314

Coulomb explosion of the hot spot of micropinches

NASA Astrophysics Data System (ADS)

Oreshkin, V. I.; Oreshkin, E. V.

2017-01-01

It has been shown that the generation of hard X-ray radiation, electron beam, and high energy ions that have been detected in experiments on compressing pinches can be related to the Coulomb explosion of a micropinch hot spot, which is formed due to the outflow of the material. In the outflow process, the plasma temperature in the hot spot increases and conditions appear for the transition of electrons to the regime of continuous acceleration. The exit of runaway electrons from the hot spot region leads to the creation of a positive bulk charge, then to a Coulomb explosion. Conditions under which electrons pass to the continuous acceleration regime have been determined and estimates of the ion kinetic energy upon a Coulomb explosion have been obtained.

Jovian longitudinal asymmetry in Io-related and Europa-related auroral hot spots

NASA Technical Reports Server (NTRS)

Dessler, A. J.; Chamberlain, J. W.

1979-01-01

Auroral emissions generated by the Jovian moons Io and Europa, originating at the foot of the magnetic flux tubes of the satellites, may be largely limited to longitudes where the planet's ionospheric conductivity is enhanced. The enhanced conductivity is produced by trapped energetic electrons that drift into the Jovian atmosphere in regions where the planet's magnetic field is anomalously weak. The most active auroral hot-spot emissions lie in a sector of the northern hemisphere defined by decametric radio emission. Weaker auroral hot spots are found in the southern hemisphere along a magnetic conjugate trace. The brightness and the longitude of the Jovian hot spots predicted in this paper are in agreement with observations reported by Atreya et al. (1977).

Mapping Sensory Spots for Moderate Temperatures on the Back of Hand.

PubMed

Yang, Fan; Chen, Guixu; Zhou, Sikai; Han, Danhong; Xu, Jingjing; Xu, Shengyong

2017-12-04

Thermosensation with thermoreceptors plays an important role in maintaining body temperature at an optimal state and avoiding potential damage caused by harmful hot or cold environmental temperatures. In this work, the locations of sensory spots for sensing moderate temperatures of 40-50 °C on the back of the hands of young Chinese people were mapped in a blind-test manner with a thermal probe of 1.0 mm spatial resolution. The number of sensory spots increased along with the testing temperature; however, the surface density of sensory spots was remarkably lower than those reported previously. The locations of the spots were irregularly distributed and subject-dependent. Even for the same subject, the number and location of sensory spots were unbalanced and asymmetric between the left and right hands. The results may offer valuable information for designing artificial electronic skin and wearable devices, as well as for clinical applications.

X-ray penumbral imaging diagnostic developments at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Bachmann, B.; Abu-Shawareb, H.; Alexander, N.; Ayers, J.; Bailey, C. G.; Bell, P.; Benedetti, L. R.; Bradley, D.; Collins, G.; Divol, L.; Döppner, T.; Felker, S.; Field, J.; Forsman, A.; Galbraith, J. D.; Hardy, C. M.; Hilsabeck, T.; Izumi, N.; Jarrot, C.; Kilkenny, J.; Kramer, S.; Landen, O. L.; Ma, T.; MacPhee, A.; Masters, N.; Nagel, S. R.; Pak, A.; Patel, P.; Pickworth, L. A.; Ralph, J. E.; Reed, C.; Rygg, J. R.; Thorn, D. B.

2017-08-01

X-ray penumbral imaging has been successfully fielded on a variety of inertial confinement fusion (ICF) capsule implosion experiments on the National Ignition Facility (NIF). We have demonstrated sub-5 μm resolution imaging of stagnated plasma cores (hot spots) at x-ray energies from 6 to 30 keV. These measurements are crucial for improving our understanding of the hot deuterium-tritium fuel assembly, which can be affected by various mechanisms, including complex 3-D perturbations caused by the support tent, fill tube or capsule surface roughness. Here we present the progress on several approaches to improve x-ray penumbral imaging experiments on the NIF. We will discuss experimental setups that include penumbral imaging from multiple lines-of-sight, target mounted penumbral apertures and variably filtered penumbral images. Such setups will improve the signal-to-noise ratio and the spatial imaging resolution, with the goal of enabling spatially resolved measurements of the hot spot electron temperature and material mix in ICF implosions.

CT-guided automated detection of lung tumors on PET images

NASA Astrophysics Data System (ADS)

Cui, Yunfeng; Zhao, Binsheng; Akhurst, Timothy J.; Yan, Jiayong; Schwartz, Lawrence H.

2008-03-01

The calculation of standardized uptake values (SUVs) in tumors on serial [ 18F]2-fluoro-2-deoxy-D-glucose ( 18F-FDG) positron emission tomography (PET) images is often used for the assessment of therapy response. We present a computerized method that automatically detects lung tumors on 18F-FDG PET/Computed Tomography (CT) images using both anatomic and metabolic information. First, on CT images, relevant organs, including lung, bone, liver and spleen, are automatically identified and segmented based on their locations and intensity distributions. Hot spots (SUV >= 1.5) on 18F-FDG PET images are then labeled using the connected component analysis. The resultant "hot objects" (geometrically connected hot spots in three dimensions) that fall into, reside at the edges or are in the vicinity of the lungs are considered as tumor candidates. To determine true lesions, further analyses are conducted, including reduction of tumor candidates by the masking out of hot objects within CT-determined normal organs, and analysis of candidate tumors' locations, intensity distributions and shapes on both CT and PET. The method was applied to 18F-FDG-PET/CT scans from 9 patients, on which 31 target lesions had been identified by a nuclear medicine radiologist during a Phase II lung cancer clinical trial. Out of 31 target lesions, 30 (97%) were detected by the computer method. However, sensitivity and specificity were not estimated because not all lesions had been marked up in the clinical trial. The method effectively excluded the hot spots caused by mediastinum, liver, spleen, skeletal muscle and bone metastasis.

Identifying tumor vascular permeability heterogeneity using reduced encoding techniques

NASA Astrophysics Data System (ADS)

Aref, Michael

We test the hypothesis that the loss of spatial resolution to gain temporal resolution in clinical dynamic contrast enhanced (DCE) magnetic resonance mammography (MRM) causes partial volume effects that yield inaccurate permeability-surface area products (PS = Kp↔t) which results in erroneous diagnostic information and we offer a potential solution using reduced encoding techniques to solve this problem. We compared the PS obtained from DCE MRI at clinical MRI resolutions (2500 x 2500 mum resolution), to that obtained from resolutions analogous to histopathological in plane resolutions (938 x 938 mum and 469 x 469 mum resolution). Secondly, we determined the accuracy of PS obtained from Keyhole, Ṟeduced-encoding I&barbelow;maging by G&barbelow;eneralized-series Ṟeconstruction (RIGR), and Ṯwo-reference RIGR (TRIGR) using high-resolution baseline data (469 x 469 mum resolution) and clinical resolution dynamic data (2500 x 2500 mum resolution). Lastly, we statistically correlated two-compartment model fitting parameters (tumor EES volume fraction, ve, tumor plasma volume fraction, vp, and PS) obtained from DCE MRI at all three resolutions to histopathologically determined tumor diagnosis. In our model, female Sprague Dawley rats with N-ethyl-N-nitrosourea (ENU) induced mammary tumors imaged with fast T1-weighted gradient echo DCE MRI following a Gd-DTPA injection, there is a window of resolutions that detects similar PS "hot spots" compared to those obtained from the clinical imager resolution. The top five PS "hot spots" obtained from 469 mum resolution FFT are statistically different from those at 938 mum resolution FFT, p = 0.0014, and 2500 mum resolution FFT, p < 0.0001. Keyhole when compared with a FFT of similar resolution does not detect PS "hot spots" of similar value, p = 0.0002. PS "hot spots" obtained from RIGR compared to those from FFT are statistically the same value, p = 0.2734, but do not statistically agree on the location of mapped values. The top five Kp↔t/VT "hot spots" and their corresponding ve can statistically differentiate invasive ductal carcinoma from non-invasive papillary carcinoma for the 469 mum and 938 mum resolution, p = 0.0017 and p = 0.0047, respectively, but not for 2500 mum resolution, p = 0.9008.

Urogenital schistosomiasis transmission on Unguja Island, Zanzibar: characterisation of persistent hot-spots.

PubMed

Pennance, Tom; Person, Bobbie; Muhsin, Mtumweni Ali; Khamis, Alipo Naim; Muhsin, Juma; Khamis, Iddi Simba; Mohammed, Khalfan Abdallah; Kabole, Fatma; Rollinson, David; Knopp, Stefanie

2016-12-16

Elimination of urogenital schistosomiasis transmission is a priority for the Zanzibar Ministry of Health. Preventative chemotherapy together with additional control interventions have successfully alleviated much of the disease burden. However, a persistently high Schistosoma haematobium prevalence is found in certain areas. Our aim was to characterise and evaluate these persistent "hot-spots" of transmission and reinfection in comparison with low-prevalence areas, to support the intervention planning for schistosomiasis elimination in Zanzibar. Prevalences of S. haematobium were annually determined by a single urine filtration in schoolchildren from 45 administrative areas (shehias) in Unguja in 2012, 2013 and 2014. Coverage data for biannual treatment with praziquantel were available from ministerial databases and internal surveys. Among the 45 shehias, five hot-spot (≥ 15 % prevalence) and two low-prevalence (≤ 5 %) shehias were identified and surveyed in mid-2014. Human-water contact sites (HWCSs) and the presence of S. haematobium-infected and uninfected Bulinus globosus, as well as safe water sources (SWSs) and their reliability in terms of water availability were determined and mapped. We found no major difference in the treatment coverage between persistent hot-spot and low-prevalence shehias. On average, there were considerably more HWCSs containing B. globosus in hot-spot than in low-prevalence shehias (n = 8 vs n = 2) and also more HWCSs containing infected B. globosus (n = 2 vs n = 0). There was no striking difference in the average abundance of SWSs in hot-spot and low-prevalence shehias (n = 45 vs n = 38) and also no difference when considering SWSs with a constant water supply (average: 62 % vs 62 %). The average number of taps with a constant water supply, however, was lower in hot-spot shehias (n = 7 vs n = 14). Average distances from schools to the nearest HWCS were considerably shorter in hot-spot shehias (n = 229 m vs n = 722 m). The number of HWCSs, their infestation with B. globosus and their distance to schools seem to play a major role for a persistently high S. haematobium prevalence in children. In addition to treatment, increasing access to reliably working taps, targeted snail control at HWCSs near schools and enhanced behaviour change measures are needed to reduce prevalences in hot-spot areas and to finally reach elimination. ISRCTN48837681 .

Small Molecules Engage Hot Spots through Cooperative Binding To Inhibit a Tight Protein-Protein Interaction.

PubMed

Liu, Degang; Xu, David; Liu, Min; Knabe, William Eric; Yuan, Cai; Zhou, Donghui; Huang, Mingdong; Meroueh, Samy O

2017-03-28

Protein-protein interactions drive every aspect of cell signaling, yet only a few small-molecule inhibitors of these interactions exist. Despite our ability to identify critical residues known as hot spots, little is known about how to effectively engage them to disrupt protein-protein interactions. Here, we take advantage of the ease of preparation and stability of pyrrolinone 1, a small-molecule inhibitor of the tight interaction between the urokinase receptor (uPAR) and its binding partner, the urokinase-type plasminogen activator uPA, to synthesize more than 40 derivatives and explore their effect on the protein-protein interaction. We report the crystal structure of uPAR bound to previously discovered pyrazole 3 and to pyrrolinone 12. While both 3 and 12 bind to uPAR and compete with a fluorescently labeled peptide probe, only 12 and its derivatives inhibit the full uPAR·uPA interaction. Compounds 3 and 12 mimic and engage different hot-spot residues on uPA and uPAR, respectively. Interestingly, 12 is involved in a π-cation interaction with Arg-53, which is not considered a hot spot. Explicit-solvent molecular dynamics simulations reveal that 3 and 12 exhibit dramatically different correlations of motion with residues on uPAR. Free energy calculations for the wild-type and mutant uPAR bound to uPA or 12 show that Arg-53 interacts with uPA or with 12 in a highly cooperative manner, thereby altering the contributions of hot spots to uPAR binding. The direct engagement of peripheral residues not considered hot spots through π-cation or salt-bridge interactions could provide new opportunities for enhanced small-molecule engagement of hot spots to disrupt challenging protein-protein interactions.

Calculation methods study on hot spot stress of new girder structure detail

NASA Astrophysics Data System (ADS)

Liao, Ping; Zhao, Renda; Jia, Yi; Wei, Xing

2017-10-01

To study modeling calculation methods of new girder structure detail's hot spot stress, based on surface extrapolation method among hot spot stress method, a few finite element analysis models of this welded detail were established by finite element software ANSYS. The influence of element type, mesh density, different local modeling methods of the weld toe and extrapolation methods was analyzed on hot spot stress calculation results at the toe of welds. The results show that the difference of the normal stress in the thickness direction and the surface direction among different models is larger when the distance from the weld toe is smaller. When the distance from the toe is greater than 0.5t, the normal stress of solid models, shell models with welds and non-weld shell models tends to be consistent along the surface direction. Therefore, it is recommended that the extrapolated point should be selected outside the 0.5t for new girder welded detail. According to the results of the calculation and analysis, shell models have good grid stability, and extrapolated hot spot stress of solid models is smaller than that of shell models. So it is suggested that formula 2 and solid45 should be carried out during the hot spot stress extrapolation calculation of this welded detail. For each finite element model under different shell modeling methods, the results calculated by formula 2 are smaller than those of the other two methods, and the results of shell models with welds are the largest. Under the same local mesh density, the extrapolated hot spot stress decreases gradually with the increase of the number of layers in the thickness direction of the main plate, and the variation range is within 7.5%.

Jumping-droplet electronics hot-spot cooling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oh, Junho; Birbarah, Patrick; Foulkes, Thomas

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobicmore » surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm 2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm 2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.« less

Jumping-droplet electronics hot-spot cooling

DOE PAGES

Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; ...

2017-03-20

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobicmore » surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm 2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm 2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.« less

Lorenz curve and Gini coefficient reveal hot spots and hot moments for nitrous oxide emissions

USDA-ARS?s Scientific Manuscript database

Identifying hot spots and hot moments of N2O emissions in the landscape is critical for monitoring and mitigating the emission of this powerful greenhouse gas. We propose a novel use of the Lorenz curve and Gini coefficient (G) to quantify the heterogeneous distribution of N2O emissions from a lands...

40 CFR 93.109 - Criteria and procedures for determining conformity of transportation plans, programs, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

...) through (k) of this section explain when the budget, interim emissions, and hot-spot tests are required... § 93.115 Project from a conforming plan and TIP § 93.116 CO, PM10, and PM2.5 hot-spots. § 93.117 PM10... Currently conforming plan and TIP § 93.116 CO, PM10, and PM2.5 hot-spots. § 93.117 PM10 and PM2.5 control...

40 CFR 93.109 - Criteria and procedures for determining conformity of transportation plans, programs, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

...) through (k) of this section explain when the budget, interim emissions, and hot-spot tests are required... § 93.115 Project from a conforming plan and TIP § 93.116 CO, PM10, and PM2.5 hot-spots. § 93.117 PM10... Currently conforming plan and TIP § 93.116 CO, PM10, and PM2.5 hot-spots. § 93.117 PM10 and PM2.5 control...

The hot spot of vegetation canopies

NASA Technical Reports Server (NTRS)

Myneni, Ranga B.; Kanemasu, Edward T.

1988-01-01

A conventional radiometer is used to identify the hot spot (the peak in reflected radiation in the retrosolar direction) of vegetation. A multiwavelength-band radiometer collected radiances on fully grown dense wheat and maize canopies on several clear sunny days. It is noted that the hot spot is difficult to detect in the near IR wavelengths because the shadows are much darker. In general, the retrosolar brightness is found to be higher for smaller sun polar angles than for larger angles.

Wetted Foam Liquid DT Layer ICF Experiments at the NIF

NASA Astrophysics Data System (ADS)

Olson, R. E.; Leeper, R. J.; Peterson, R. R.; Yi, S. A.; Zylstra, A. B.; Kline, J. L.; Bradley, P. A.; Yin, L.; Wilson, D. C.; Haines, B. M.; Batha, S. H.

2016-10-01

A key physics issue in indirect-drive ICF relates to the understanding of the limitations on hot spot convergence ratio (CR), principally set by the hohlraum drive symmetry, the capsule mounting hardware (the ``tent''), and the capsule fill tube. An additional key physics issue relates to the complex process by which a hot spot must be dynamically formed from the inner ice surface in a DT ice-layer implosion. These physics issues have helped to motivate the development of a new liquid DT layer wetted foam platform at the NIF that provides an ability to form the hot spot from DT vapor and experimentally study and understand hot spot formation at a variety of CR's in the range of 12

Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice.

PubMed

de Boer, Esther; Jasin, Maria; Keeney, Scott

2015-08-15

Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency. © 2015 de Boer et al.; Published by Cold Spring Harbor Laboratory Press.

A Comparison of the Hot Spot and the Average Cancer Cell Counting Methods and the Optimal Cutoff Point of the Ki-67 Index for Luminal Type Breast Cancer.

PubMed

Arima, Nobuyuki; Nishimura, Reiki; Osako, Tomofumi; Nishiyama, Yasuyuki; Fujisue, Mamiko; Okumura, Yasuhiro; Nakano, Masahiro; Tashima, Rumiko; Toyozumi, Yasuo

2016-01-01

In this case-control study, we investigated the most suitable cell counting area and the optimal cutoff point of the Ki-67 index. Thirty recurrent cases were selected among hormone receptor (HR)-positive/HER2-negative breast cancer patients. As controls, 90 nonrecurrent cases were randomly selected by allotting 3 controls to each recurrent case based on the following criteria: age, nodal status, tumor size, and adjuvant endocrine therapy alone. Both the hot spot and the average area of the tumor were evaluated on a Ki-67 immunostaining slide. The median Ki-67 index value at the hot spot and average area were 25.0 and 14.5%, respectively. Irrespective of the area counted, the Ki-67 index value was significantly higher in all of the recurrent cases (p < 0.0001). The multivariate analysis revealed that the Ki-67 index value of 20% at the hot spot was the most suitable cutoff point for predicting recurrence. Moreover, higher x0394;Ki-67 index value (the difference between the hot spot and the average area, ≥10%) and lower progesterone receptor expression (<20%) were significantly correlated with recurrence. A higher Ki-67 index value at the hot spot strongly correlated with recurrence, and the optimal cutoff point was found to be 20%. © 2015 S. Karger AG, Basel.

Criticality and Induction Time of Hot Spots in Detonating Heterogeneous Explosives

NASA Astrophysics Data System (ADS)

Hill, Larry

2017-06-01

Detonation reaction in physically heterogeneous explosives is-to an extent that depends on multiple material attributes-likewise heterogeneous. Like all heterogeneous reaction, detonation heterogeneous reaction begins at nucleation sites, which, in this case, comprise localized regions of higher-than-average temperature-so-called hot spots. Burning grows at, and then spreads from these nucleation sites, via reactive-thermal (R-T) waves, to consume the interstitial material. Not all hot spots are consequential, but only those that are 1) supercritical, and 2) sufficiently so as to form R-T waves before being consumed by those already emanating from neighboring sites. I explore aspects of these two effects by deriving simple formulae for hot spot criticality and the induction time of supercritical hot spots. These results serve to illustrate the non-intuitive, yet mathematically simplifying, effects of extreme dependence of reaction rate upon temperature. They can play a role in the development of better reactive burn models, for which we seek to homogenize the essentials of heterogeneous detonation reaction without introducing spurious complexity. Work supported by the US Dept. of Energy.

Shock initiation of explosives: High temperature hot spots explained

NASA Astrophysics Data System (ADS)

Bassett, Will P.; Johnson, Belinda P.; Neelakantan, Nitin K.; Suslick, Kenneth S.; Dlott, Dana D.

2017-08-01

We investigated the shock initiation of energetic materials with a tabletop apparatus that uses km s-1 laser-driven flyer plates to initiate tiny explosive charges and obtains complete temperature histories with a high dynamic range. By comparing various microstructured formulations, including a pentaerythritol tetranitrate (PETN) based plastic explosive (PBX) denoted XTX-8003, we determined that micron-scale pores were needed to create high hot spot temperatures. In charges where micropores (i.e., micron-sized pores) were present, a hot spot temperature of 6000 K was observed; when the micropores were pre-compressed to nm scale, however, the hot spot temperature dropped to ˜4000 K. By comparing XTX-8003 with an analog that replaced PETN by nonvolatile silica, we showed that the high temperatures require gas in the pores, that the high temperatures were created by adiabatic gas compression, and that the temperatures observed can be controlled by the choice of ambient gases. The hot spots persist in shock-compressed PBXs even in vacuum because the initially empty pores became filled with gas created in-situ by shock-induced chemical decomposition.

Two New Hot Spots on Io

NASA Technical Reports Server (NTRS)

1997-01-01

The Near-Infrared Mapping Spectrometer (NIMS) on Galileo obtained this image of half of Io's disk in darkness on September 19, 1997. This image, at 5 microns, shows several hot spots on Io, which are volcanic regions of enhanced thermal emission. The area shown is part of the leading hemisphere of Io.

Two new hot spots are shown and indicated in the image (New, and Shamshu). Neither of these hot spots were seen by NIMS or the Solid State Imaging Experiment, (SSI) prior to this observation, becoming only recently active. Several other previously known hot spots are labelled in the image. Galileo was at a distance of 342,000 km from Io when this observation was made.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

Hot-spot tectonics on Io

NASA Technical Reports Server (NTRS)

Mcewen, A. S.

1985-01-01

The thesis is that extensional tectonics and low-angle detachment faults probably occur on Io in association with the hot spots. These processes may occur on a much shorter timescale on Ion than on Earth, so that Io could be a natural laboratory for the study of thermotectonics. Furthermore, studies of heat and detachment in crustal extension on Earth and the other terresrial planets (especially Venus and Mars) may provide analogs to processes on Io. The geology of Io is dominated by volcanism and hot spots, most likely the result of tidal heating. Hot spots cover 1 to 2% of Io's surface, radiating at temperatures typically from 200 to 400 K, and occasionally up to 700K. Heat loss from the largest hot spots on Io, such as Loki Patera, is about 300 times the heat loss from Yellowstone, so a tremendous quantity of energy is available for volcanic and tectonic work. Active volcanism on Io results in a resurfacing rate as high as 10 cm per year, yet many structural features are apparent on the surface. Therefore, the tectonics must be highly active.

Measurement of the hot spot electron temperature in NIF ICF implosions using Krypton x-ray emission spectroscopy

NASA Astrophysics Data System (ADS)

Ma, T.; Chen, H.; Patel, P. K.; Schneider, M.; Barrios, M.; Berzak Hopkins, L.; Casey, D.; Chung, H.-K.; Hammel, B.; Jarrott, C.; Nora, R.; Pak, A.; Scott, H.; Spears, B.; Weber, C.

2015-11-01

The inference of ion temperature from neutron spectral measurements in indirect-drive ICF implosions is known to be sensitive to non-thermal velocity distributions in the fuel. The electron temperature (Te) inferred from dopant line ratios should not be sensitive to these bulk motions and hence may be a better measure of the thermal temperature of the hot spot. Here we describe a series of experiments to be conducted on the NIF where a small concentration of a mid-Z dopant (Krypton) is added to the fuel gas. The x-ray spectra is measured and the electron temperature is inferred from Kr line ratios. We also quantify the level of radiative cooling in the hot spot due to this mid-Z dopant. These experiments represent the first direct measurement of hot spot Te using spectroscopy, and we will describe the considerations for applying x-ray spectroscopy in such dense and non-uniform hot spots. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

A Model of Mantle Plume Based on Hawaiian Magmatism

NASA Astrophysics Data System (ADS)

Takahashi, E.

2001-12-01

In order to constrain the chemistry and temperature of the hot rising material (mantle plume), we have studied growth history of Koolau volcano in Hawaii based on reconstruction of giant submarine landslides (Evolution of Hawaiian Volcanoes, AGU Monograph, 2001). Based on petrology of the Koolau lava and high-pressure melting experiments, we propose a model that the Hawaiian plume has a potential mantle temperature (PMT) of only 1400C and the primitive magma at the final growth stage of Koolau volcano (Makapuu stage) was formed by extensive melting of a large block of recycled old oceanic crust (eclogite block of 1000km3 in volume). Our PMT is much lower than the estimate for the modern Hawaiian plume by Watson and McKenzie (1991, PMT=1558C) assuming homogeneous peridotite source. Melting experiments of basalt/peridotite hybrid source at 3 GPa (Takahashi and Nakajima, 2001) show that only slight temperature increase (less than 50deg) will shift the Koolau type primary melts (SiO2=53, MgO=7 wt.%) to the parental Mauna Loa and Kilauea type melts (SiO2=49, MgO=14). Geometry of the partial melt zone surrounding upwelling eclogite blocks may cause the inter-shield chemical variation among the Hawaiian volcanoes. The lower plume temperature and the existence of large blocks of former oceanic crust in the plume require reconsideration on the origin of the mantle plume and the mechanism of its upwelling transport. Presence or absence of the old oceanic crust in the plume will explain chemical diversity and the contrasting melt productivity between hot spots (e.g., Iceland vs. Azores). The large low velocity anomaly down to the CMB underneath the South Pacific hot spots (most distinct in global tomography), presently yields smaller magma flux than a single Hawaiian hot spot. The South Pacific plume may consist of upwelling warm hurzburgite (depleted ancient oceanic lithosphere). The South Pacific hot spot however was very magma productive in the Cretaceous time when large amount of recycled oceanic crust was entrained in the same plume. High-pressure experiments on density of subducted oceanic crust suggest that much of the subducted eclogite is stored above the 660km discontinuity. The fluctuation in magmatism in given hot spots may be explained by the interaction of the eclogite stock layer and the ascending plume.

Ridge Jumps Associated with Plume-Ridge Interaction 1: Off-axis Heating due to Lithospheric Magma Penetration

NASA Astrophysics Data System (ADS)

Mittelstaedt, E.; Ito, G.

2005-12-01

In many hot spot-ridge systems, changes in the ridge axis geometry occur between the hot spot centers and nearby mid-ocean ridges in the form of ridge jumps. Such ridge jumps likely occur as a result of anomalous lithospheric stresses associated with mantle plume-lithosphere interaction, as well as weakening of the hot spot lithosphere due to physical and thermal thinning caused by rising buoyant asthenosphere and magma transport through the lithosphere. In this study, we use numerical models to quantify the effects of excess magmatism through the near-ridge lithosphere. Hot spot magmatism can weaken the lithosphere both mechanically through fracturing and thermally through conduction and advection of heat into the plate. Here we focus on the effects of thermal weakening. Using a plane-strain approximation, we examine deformation in a 2-D cross section of a visco-elastic-plastic lithosphere with the finite element code FLAC. The model has isothermal top and bottom boundaries and a prescribed velocity equal to the half spreading rate is imposed on the sides to drive seafloor spreading. The initial condition, as predicted for normal mid-ocean ridges, is a square root of lithospheric age cooling curve with a corner flow velocity field symmetric about the ridge axis. A range of heat inputs are introduced at various plate ages and spreading rates to simulate off-axis magma transport. To reveal the physical conditions that allow for a ridge jump and control its timing, we vary 4 parameters: spreading rate, lithospheric age, crustal thickness and heat input. Results indicate that the heating rate required to produce a ridge jump increases as a function of lithospheric age at the location of magma intrusion. The time necessary for a ridge jump to develop in lithosphere of a particular age decreases with increasing crustal thicknesses. For magma fluxes comparable to those estimated for Galapagos and Iceland, lithospheric heating by the penetrating magma alone is sufficient to cause a ridge jump, even without the other effects.

Three Dimensional Analysis of Induced Detonation of Cased Explosive

DTIC Science & Technology

2014-10-16

hardness and ductility . RHA steel is largely used in military applications to manufacture armoured vehicles. The Johnson Cook (JC) constitutive...armour (RHA) steel were investigated through the LS-DYNA. The investigation focused on shock to detonation simulations of Composition B, with the... hot spots caused by the compression of the explosive from the initial shockwave. Detonation was also caused by pressure waves reflecting against the

Lessons from Hot Spot Analysis for Fragment-Based Drug Discovery.

PubMed

Hall, David R; Kozakov, Dima; Whitty, Adrian; Vajda, Sandor

2015-11-01

Analysis of binding energy hot spots at protein surfaces can provide crucial insights into the prospects for successful application of fragment-based drug discovery (FBDD), and whether a fragment hit can be advanced into a high-affinity, drug-like ligand. The key factor is the strength of the top ranking hot spot, and how well a given fragment complements it. We show that published data are sufficient to provide a sophisticated and quantitative understanding of how hot spots derive from a protein 3D structure, and how their strength, number, and spatial arrangement govern the potential for a surface site to bind to fragment-sized and larger ligands. This improved understanding provides important guidance for the effective application of FBDD in drug discovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Measurement of Hot-Spots in Granulated Ammonium Nitrate

NASA Astrophysics Data System (ADS)

Proud, W. G.

2002-07-01

Ammonium Nitrate (AN) is one of the components of the most widely used explosive in the world namely, ammonium nitrate: fuel oil mixtures (ANFO). By itself, it is an oxygen positive explosive with a large critical diameter. Hot-spots are produced in explosives by various means including gas space collapse, localised shear or friction. If these hot-spots reach critical conditions of size, temperature and duration reaction can grow. This deflagration stage may eventually transition to detonation. This paper describes high-speed image-intensified photography study in which the number and growth of hot spots in granular AN are monitored for a range of different impact pressures. The results can be used in detonation codes to provide a more accurate and realistic description of the initiation process.

The Measurement of Hot-spots in Granulated Ammonium Nitrate

NASA Astrophysics Data System (ADS)

Proud, William; Field, John

2001-06-01

Ammonium Nitrate (AN) is one of the components of the most widely used explosive in the world ammonium nitrate: fuel oil mixtures (ANFO). By itself, it is an oxygen negative explosive with a large critical diameter. Hot-spots are produced in explosives by various means including gas space collapse, localised shear or friction. If these hot-spots reach critical conditions of size, temperature and duration size reaction can grow. This deflagration stage may eventually transition to detonation. This paper describes a system and presents results where high-speed image intensified photography is used to monitor the number and growth of hot spots in granular AN under a range of different impact pressures. The results can be used in detonation codes to provide a more accurate and realistic description of the initiation process.

Detecting fluorescence hot-spots using mosaic maps generated from multimodal endoscope imaging

NASA Astrophysics Data System (ADS)

Yang, Chenying; Soper, Timothy D.; Seibel, Eric J.

2013-03-01

Fluorescence labeled biomarkers can be detected during endoscopy to guide early cancer biopsies, such as high-grade dysplasia in Barrett's Esophagus. To enhance intraoperative visualization of the fluorescence hot-spots, a mosaicking technique was developed to create full anatomical maps of the lower esophagus and associated fluorescent hot-spots. The resultant mosaic map contains overlaid reflectance and fluorescence images. It can be used to assist biopsy and document findings. The mosaicking algorithm uses reflectance images to calculate image registration between successive frames, and apply this registration to simultaneously acquired fluorescence images. During this mosaicking process, the fluorescence signal is enhanced through multi-frame averaging. Preliminary results showed that the technique promises to enhance the detectability of the hot-spots due to enhanced fluorescence signal.

Dust as the cause of spots on Jupiter

NASA Technical Reports Server (NTRS)

Field, G. B.; Tozzi, G. P.; Stanga, R. M.

1995-01-01

The long-lived spots caused by the impact of fragments of Comet S-L 9 on Jupiter can be understood if clouds of dust are produced by the impact. These clouds reside in the stratosphere, where they absorb visible light that would ordinarily reflect from the cloud deck below, and reflect radiation at infrared wavelengths that would ordinarily be absorbed by atmospheric methane. Here we show that, provided that the nucleus of a fragment is composed substantially of silicates and has a diameter greater than about 0.4 km, dust in the required amounts will condense from the hot gas composed of cometary and Jovian material ejected from the site where the fragment entered, and the dust will be suspended in the stratosphere for long periods. Particles about 1 micron in radius can explain both the optical properties and longevities of the spots. According to our model, a silicate band should be present in the 10 - micron spectra of the spots.

Ultrafast Surface-Enhanced Raman Probing of the Role of Hot Electrons in Plasmon-Driven Chemistry.

PubMed

Brandt, Nathaniel C; Keller, Emily L; Frontiera, Renee R

2016-08-18

Hot electrons generated through plasmonic excitations in metal nanostructures show great promise for efficiently driving chemical reactions with light. However, the lifetime, yield, and mechanism of action of plasmon-generated hot electrons involved in a given photocatalytic process are not well understood. Here, we develop ultrafast surface-enhanced Raman scattering (SERS) as a direct probe of plasmon-molecule interactions in the plasmon-catalyzed dimerization of 4-nitrobenzenethiol to p,p'-dimercaptoazobenzene. Ultrafast SERS probing of these molecular reporters in plasmonic hot spots reveals transient Fano resonances, which we attribute to near-field coupling of Stokes-shifted photons to hot electron-driven metal photoluminescence. Surprisingly, we find that hot spots that yield more photoluminescence are much more likely to drive the reaction, which indirectly proves that plasmon-generated hot electrons induce the photochemistry. These ultrafast SERS results provide insight into the relative reactivity of different plasmonic hot spot environments and quantify the ultrafast lifetime of hot electrons involved in plasmon-driven chemistry.

Resolving Hot Spots in the C-Terminal Dimerization Domain that Determine the Stability of the Molecular Chaperone Hsp90

PubMed Central

Reimann, Sven; Smits, Sander H. J.; Schmitt, Lutz; Groth, Georg; Gohlke, Holger

2014-01-01

Human heat shock protein of 90 kDa (hHsp90) is a homodimer that has an essential role in facilitating malignant transformation at the molecular level. Inhibiting hHsp90 function is a validated approach for treating different types of tumors. Inhibiting the dimerization of hHsp90 via its C-terminal domain (CTD) should provide a novel way to therapeutically interfere with hHsp90 function. Here, we predicted hot spot residues that cluster in the CTD dimerization interface by a structural decomposition of the effective energy of binding computed by the MM-GBSA approach and confirmed these predictions using in silico alanine scanning with DrugScorePPI. Mutation of these residues to alanine caused a significant decrease in the melting temperature according to differential scanning fluorimetry experiments, indicating a reduced stability of the mutant hHsp90 complexes. Size exclusion chromatography and multi-angle light scattering studies demonstrate that the reduced stability of the mutant hHsp90 correlates with a lower complex stoichiometry due to the disruption of the dimerization interface. These results suggest that the identified hot spot residues can be used as a pharmacophoric template for identifying and designing small-molecule inhibitors of hHsp90 dimerization. PMID:24760083

Online Adaptive Hyperthermia Treatment Planning During Locoregional Heating to Suppress Treatment-Limiting Hot Spots.

PubMed

Kok, H Petra; Korshuize-van Straten, Linda; Bakker, Akke; de Kroon-Oldenhof, Rianne; Geijsen, Elisabeth D; Stalpers, Lukas J A; Crezee, Johannes

2017-11-15

Adequate tumor temperatures during hyperthermia are essential for good clinical response, but excessive heating of normal tissue should be avoided. This makes locoregional heating using phased array systems technically challenging. Online application of hyperthermia treatment planning could help to improve the heating quality. The aim of this study was to evaluate the clinical benefit of online treatment planning during treatment of pelvic tumors heated with the AMC-8 locoregional hyperthermia system. For online adaptive hyperthermia treatment planning, a graphical user interface was developed. Electric fields were calculated in a preprocessing step using our in-house-developed finite-difference-based treatment planning system. This allows instant calculation of the temperature distribution for user-selected phase-amplitude settings during treatment and projection onto the patient's computed tomographic scan for online visualization. Online treatment planning was used for 14 treatment sessions in 8 patients to reduce the patients' reports of hot spots while maintaining the same level of tumor heating. The predicted decrease in hot spot temperature should be at least 0.5°C, and the tumor temperature should decrease less than 0.2°C. These predictions were compared with clinical data: patient feedback about the hot spot and temperature measurements in the tumor region. In total, 17 hot spot reports occurred during the 14 sessions, and the alternative settings predicted the hot spot temperature to decrease by at least 0.5°C, which was confirmed by the disappearance of all 17 hot spot reports. At the same time, the average tumor temperature was predicted to change on average -0.01°C (range, -0.19°C to 0.34°C). The measured tumor temperature change was on average only -0.02°C (range, -0.26°C to 0.31°C). In only 2 cases the temperature decrease was slightly larger than 0.2°C, but at most it was 0.26°C. Online application of hyperthermia treatment planning is reliable and very useful to reduce hot spots without affecting tumor temperatures. Copyright © 2017 Elsevier Inc. All rights reserved.

Hot Accretion Spots and Nitrogen Enhancement in Algol-Type Interacting Binary Systems

NASA Astrophysics Data System (ADS)

Peters, Geraldine J.

2013-07-01

The shock from the impact of a gas stream onto the photosphere of a mass gainer in an Algol system is expected to produce a hot spot and also heat circumstellar material that is splashed from the impact site. Furthermore in some cases we expect the stripped-down mass loser (a late-type subgiant) to be nitrogen rich and carbon poor if CNO-processed material is currently being transferred. I will present observational evidence from the Kepler and FUSE spacecrafts for the presence of hot spots and discuss their behavior. FUSE observations of Algols that convincingly show that the gas stream material from some Algol secondaries is N-enhanced and virtually devoid of carbon is also presented. From Kepler data we have identified a long-term phenomenon in which the relative brightness of the quadrature light varies by a few percent and numerically reverses over a time scale of about a 100-400 days. We call the systems T/L (trailing hemisphere/leading hemisphere) variables. Such behavior has never been identified from ground-based photometry. WX Draconis (A8 + K0 IV, P = 1.80 d), a system whose primary displays delta Scuti-like pulsations, is the prototype. The Kepler light curves are being modeled with the latest version of the Wilson-Devinney program that includes the capability of treating migrating hot/cool spots. I will discuss whether the T/L behavior is likely due to a migrating hot accretion spot on the primary or variability in a large cool-spotted area on the secondary. From archival FUSE data we have confirmed the presence of a hot accretion spot in the Algol system U Cephei and present information on the spot parameters/behavior and conditions in a splash plasma from the impact site. Kepler and archival FUSE observations continue to provide important information on the nature of the component stars in Algol systems and the detailed physics of mass transfer, especially the role of accretion hot spots. We are grateful for support from NASA grants NNX11AC78G and NNX12AE44G.

Hot spots and hot moments in riparian zones: Potential for improved water quality management

Treesearch

Philippe Vidon; Craig Allan; Douglas Burns; Tim P. Duval; Noel Gurwick; Shreeram Inamdar; Richard Lowrance; Judy Okay; Durelle Scott; Stephen Sebestyen

2010-01-01

Biogeochemical and hydrological processes in riparian zones regulate contaminant movement to receiving waters and often mitigate the impact of upland sources of contaminants on water quality. These heterogeneous processes have recently been conceptualized as "hot spots and moments" of retention, degradation, or production. Nevertheless, studies investigating...

Enceladus' Geysers and Small-scale Thermal Hot Spots: Spatial Correlations and Implications

NASA Astrophysics Data System (ADS)

Porco, C.; Helfenstein, P.; Goguen, J.

2016-12-01

The geysering south polar terrain (SPT) of Enceladus has been a major focus of the Cassini mission ever since Cassini's first sighting of it in images taken in early 2005 (1). A high resolution imaging survey of the region conducted over the course of seven years resulted in the identification of 100 geysers erupting from the four main fractures crossing the SPT (2). The Cassini Visual and Infrared Mapping Spectrometer (VIMS) detected enhanced thermal emission arising from these fractures and taking the form of small-scale ( ≤ 10 meter) discrete spots (3,4). Four of these hot spot observations have already been spatially associated with four geysers on the Baghdad Sulcus fracture (2). The inferred spatial correlation and small size of each hot spot eliminated shear heating along the near-surface walls of the fractures as the source of the heat and erupting materials. Instead, it was concluded that condensation of vapor (and liquid), and the deposition of latent heat, on the near-surface vent walls, and the subsequent conduction of that heat to the surface, was the source of the observed thermal emission. This indicated that the hot spots are the secondary signature of a geyser eruption process deeply rooted in the moon's sub-surface liquid water reservoir (2). We extend the examination of these relationships to include seven additional VIMS observations of hot spots. At the present time, we have associated a total of 11 VIMS hot spot observations with 13 (maybe 14) geysers distributed over all four tiger stripe fractures. It's not uncommon for the locations of multiple (often two but sometimes three) surveyed geysers to overlap within estimated uncertainties. This can occur when they have different 3D orientations, making them identifiable in our 2014 survey as distinct features; However, the raw, thermally unmodeled VIMS maps, with their (relatively) coarse resolution, may register at that location only one corresponding hot spot. It is also possible that closely overlapping clusters of geysers in the survey represent a single geyser that changes its direction over the course of an Enceladus orbit as its vent widens and narrows with the diurnally varying normal stresses. Nonetheless, future thermal modeling of these VIMS hot spots should help constrain the conditions in the near-surface vents from which the geysers erupt.

Complementarity of stability patches at the interfaces of protein complexes: Implication for the structural organization of energetic hot spots.

PubMed

Kuttner, Yosef Y; Engel, Stanislav

2018-02-01

A rational design of protein complexes with defined functionalities and of drugs aimed at disrupting protein-protein interactions requires fundamental understanding of the mechanisms underlying the formation of specific protein complexes. Efforts to develop efficient small-molecule or protein-based binders often exploit energetic hot spots on protein surfaces, namely, the interfacial residues that provide most of the binding free energy in the complex. The molecular basis underlying the unusually high energy contribution of the hot spots remains obscure, and its elucidation would facilitate the design of interface-targeted drugs. To study the nature of the energetic hot spots, we analyzed the backbone dynamic properties of contact surfaces in several protein complexes. We demonstrate that, in most complexes, the backbone dynamic landscapes of interacting surfaces form complementary "stability patches," in which static areas from the opposing surfaces superimpose, and that these areas are predominantly located near the geometric center of the interface. We propose that a diminished enthalpy-entropy compensation effect augments the degree to which residues positioned within the complementary stability patches contribute to complex affinity, thereby giving rise to the energetic hot spots. These findings offer new insights into the nature of energetic hot spots and the role that backbone dynamics play in facilitating intermolecular recognition. Mapping the interfacial stability patches may provide guidance for protein engineering approaches aimed at improving the stability of protein complexes and could facilitate the design of ligands that target complex interfaces. © 2017 Wiley Periodicals, Inc.

Symmetric cumulants as a probe of the proton substructure at LHC energies

NASA Astrophysics Data System (ADS)

Albacete, Javier L.; Petersen, Hannah; Soto-Ontoso, Alba

2018-03-01

We present a systematic study of the normalized symmetric cumulants, NSC(n,m), at the eccentricity level in proton-proton interactions at √{ s } = 13TeV within a wounded hot spot approach. We focus our attention on the influence of spatial correlations between the proton constituents, in our case gluonic hot spots, on this observable. We notice that the presence of short-range repulsive correlations between the hot spots systematically decreases the values of NSC (2 , 3) and NSC (2 , 4) in mid- to ultra-central collisions while increases them in peripheral interactions. In the case of NSC (2 , 3) we find that, as suggested by data, an anti-correlation of ε2 and ε3 in ultra-central collisions, i.e. NSC (2 , 3) < 0, is possible within the correlated scenario while it never occurs without correlations when the number of gluonic hot spots is set to three. We attribute this fact to the decisive role of correlations on enlarging the probability of interaction topologies that reduce the value of NSC (2 , 3) and, eventually, make it negative. Further, we explore the dependence of our conclusions on the number of hot spots, the values of the hot spot radius and the repulsive core distance. Our results add evidence to the idea that considering spatial correlations between the subnucleonic degrees of freedom of the proton may have a strong impact on the initial state properties of proton-proton interactions [1].

Suppression of Aedes albopictus, the Asian tiger mosquito, using a 'hot spot' approach.

PubMed

Unlu, Isik; Klingler, Kim; Indelicato, Nicholas; Faraji, Ary; Strickman, Daniel

2016-07-01

Recent changes in climate and human behavior have led to dramatic increases in the abundance and geographic expansion of invasive mosquito vectors such as Aedes albopictus. Although source reduction has been shown to be effective in reducing mosquito populations, thousands of backyards need to be inspected during door-to-door campaigns, which is labor intensive and expensive. We identified 'hot spots' as high (five or more female or male Ae. albopictus) adult mosquito populations at very focal locations. We tested whether hot spot source reduction efforts were effective in reducing mosquito populations in the early summer season (June to July). Analysis of historical data from the study sites indicated the proportion of hot spots in the control site relative to the intervention site was much greater in 2011, when hot spot treatments were applied to the intervention site, than in 2012, 2013 and 2014 combined, when no sites were treated [OR (95% CI) = 3.9 (1.8, 8.5), Z = 3.39, P < 0.001). Hot spot treatments can be incorporated into existing integrated mosquito management programs to increase effectiveness while reducing the time, cost and effort spent on methods such as door-to-door source reduction. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

ESA uncovers Geminga's `hot spot'

NASA Astrophysics Data System (ADS)

2004-07-01

16 July 2004 Astronomers using ESA’s X-ray observatory XMM-Newton have detected a small, bright ‘hot spot’ on the surface of the neutron star called Geminga, 500 light-years away. The hot spot is the size of a football field and is caused by the same mechanism producing Geminga’s X-ray tails. This discovery identifies the missing link between the X-ray and gamma-ray emission from Geminga. hi-res Size hi-res: 1284 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot This figure shows the effects of charged particles accelerated in the magnetosphere of Geminga. Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of particles kicked out by Geminga’s strong magnetic field, trail the neutron star as it moves about in space. Panel (b) shows how electrically charged particles interact with Geminga’s magnetic field. For example, if electrons (blue) are kicked out by the star, positrons (in red) hit the star’s magnetic poles like in an ‘own goal’. Panel (c) illustrates the size of Geminga’s magnetic field (blue) compared to that of the star itself at the centre (purple). The magnetic field is tilted with respect to Geminga’s rotation axis (red). Panel (d) shows the magnetic poles of Geminga, where charged particles hit the surface of the star, creating a two-million degrees hot spot, a region much hotter than the surroundings. As the star spins on its rotation axis, the hot spot comes into view and then disappears, causing the periodic colour change seen by XMM-Newton. An animated version of the entire sequence can be found at: Click here for animated GIF [low resolution, animated GIF, 5536 KB] Click here for AVI [high resolution, AVI with DIVX compression, 19128 KB] hi-res Size hi-res: 371 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (a) Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of particles kicked out by Geminga’s strong magnetic field, trail the neutron star as it moves about in space. hi-res Size hi-res: 377 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (b) Panel (b) shows how electrically charged particles interact with Geminga’s magnetic field. For example, if electrons (blue) are kicked out by the star, positrons (red) hit the star’s magnetic poles like in an ‘own goal’. hi-res Size hi-res: 435 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (c) Panel (c) illustrates the size of Geminga’s magnetic field (blue) compared to that of the star itself at the centre (purple). The magnetic field is tilted with respect to Geminga’s rotation axis (red). hi-res Size hi-res: 121 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (d) Panel (d) shows the magnetic poles of Geminga, where charged particles hit the surface of the star, creating a two-million degree hot spot, a region much hotter than the surroundings. As the star spins on its rotation axis, the hot spot comes into view and then disappears, causing the periodic colour change seen by XMM-Newton. Neutron stars are the smallest kind of stars known. They are the super-dense remnants of massive stars that died in cataclysmic explosions called supernovae. They have been thrown through space like cannonballs and set spinning at a furious rate, with magnetic fields hundreds of billions of times stronger than Earth’s. In the case of Geminga, this cannonball contains one and a half times the mass of the Sun, squeezed into a sphere just 20 kilometres across and spinning four times every second. A cloud bustling with electrically charged particles surrounds Geminga. These particles are shepherded by its magnetic and electric fields. ESA’s XMM-Newton observatory had already discovered that some of these particles are ejected into space, forming tails that stream behind the neutron star as it hurtles along. Scientists did not know whether Geminga’s tails are formed by electrons or by their twin particles with an opposite electrical charge, called positrons. Nevertheless, they expected that, if for instance electrons are kicked into space, then the positrons should be funnelled down towards the neutron star itself, like in an ‘own goal’. Where these particles strike the surface of the star, they ought to create a hot spot, a region considerably hotter than the surroundings. An international team of astronomers, lead by Patrizia Caraveo, IASF-CNR, Italy, has now reported the detection of such a hot spot on Geminga using ESA’s XMM-Newton observatory. With a temperature of about two million degrees, this hot spot is considerably hotter than the one half million degrees of the surrounding surface. According to this new work, Geminga’s hot spot is just 60 metres in radius. "This hot spot is the size of a football field," said Caraveo, "and is the smallest object ever detected outside of our Solar System." Details of this size can presently be measured only on the Moon and Mars and, even then, only from a spacecraft in orbit around them. The presence of a hot spot was suspected in the late 1990s but only now can we see it ‘live’, emitting X-rays as Geminga rotates, thanks to the superior sensitivity of ESA’s X-ray observatory, XMM-Newton. The team used the European Photon Imaging Cameras (EPIC) to conduct a study of Geminga, lasting about 28 consecutive hours and recording the arrival time and energy of every X-ray photon that Geminga emitted within XMM-Newton’s grasp. "In total, this amounted to 76 850 X-ray counts - twice as many as have been collected by all previous observations of Geminga, since the time of the Roman Empire," said Caraveo. Knowing the rotation rate of Geminga and the time of each photon’s arrival meant that astronomers could identify which photons were coming from each region of the neutron star as it rotates. When they compared photons coming from different regions of the star, they found that the ‘colour’ of the X-rays, which corresponds to their energy, changed as Geminga rotated. In particular, they could clearly see a distinct colour change when the hot spot came into view and then disappeared behind the star. This research closes the gap between the X-ray and gamma-ray emission from neutron stars. XMM-Newton has shown that they both can originate through the same physical mechanism, namely the acceleration of charged particles in the magnetosphere of these degenerate stars. "XMM-Newton’s Geminga observation has been particularly fruitful," said Norbert Schartel, ESA’s Project Scientist for XMM-Newton. "Last year, it yielded the discovery of the source tails and now it has found its rotating hot spot." Caraveo is already applying this new technique to other pulsating neutron stars observed by XMM-Newton looking for hot spots. This research represents an important new tool for understanding the physics of neutron stars. Notes for editors The original paper appeared on 16 July 2004, in Science magazine, under the title 'Phase-resolved spectroscopy of Geminga shows rotating hotspot(s)'. Besides P. Caraveo, the author list includes A. De Luca, S. Mereghetti, A. Pellizzoni and G. Bignami. During the search to track down this elusive celestial object, a co-author on the paper, Giovanni Bignami, named it Geminga almost 30 years ago. He was Principal Investigator of XMM-Newton's EPIC camera from 1987 to 1997 and is now Director of the Centre d'Etude Spatiale des Rayonnements (CESR, Toulouse). Geminga was first glimpsed as a mysterious source of gamma rays, coming from somewhere in the constellation Gemini by NASA's SAS-2 spacecraft in 1973. While searching to pin down its exact location and nature, Bignami named it Geminga because it was a ‘Gemini gamma-ray source’. As an astronomer in Milan, Italy, he was also aware that in his native dialect ‘gh'èminga’ means ‘it is not there’, which he found amusing. It was also remarkably apt, for it was not until 1993 that he succeeded in finally ‘seeing’ and therefore pinpointing Geminga, using optical wavelengths. While it lacked radio emissions, the pulsating X-ray and gamma-ray emissions meant Geminga could only belong to a new class of objects, the radio-quiet neutron stars. The original announcement of the discovery of Geminga’s tails, issued on 25 July 2003, can be found at: http://www.esa.int/esaSC/Pr_11_2003_s_en.html More about XMM-Newton XMM-Newton can detect more X-ray sources than any previous observatory and is helping to solve many cosmic mysteries of the violent Universe, from black holes to the formation of galaxies. It was launched on 10 December 1999, using an Ariane-5 rocket from French Guiana. It is expected to return data for a decade. XMM-Newton’s high-tech design uses over 170 wafer-thin cylindrical mirrors spread over three telescopes. Its orbit takes it almost a third of the way to the Moon, so that astronomers can enjoy long, uninterrupted views of celestial objects. More information on XMM-Newton can be found at: http://www.esa.int/esaSC/SEMM8IGHZTD_1_spk.html

Influence of hot spot features on the shock initiation of heterogenous nitromethane

NASA Astrophysics Data System (ADS)

Dattelbaum, Dana; Sheffield, Stephen; Stahl, David; Dattelbaum, Andrew

2009-06-01

The shock initiation sensitivity of heterogeneous explosives is known to be strongly related to the confluence of ``hot spots'' or localized regions of high pressure and temperature. Physical origins of hot spots within a material include dynamic pore collapse, friction from motion along closed cracks, and wave reflections from other in situ interfaces. A complex interplay among numerous physical and chemical factors, spanning several length scales, determines whether or not a hot spot will quench or lead to initiation. To further elucidate key features of hot spots on energetic materials sensitivity and initiation mechanisms, we have intentionally introduced well-defined particles into the homogeneous liquid explosive nitromethane which has been gelled so the particles are somewhat stationary. Gas-gun driven shock initiation experiments using embedded electromagnetic gauging methods have been performed on these materials, revealing new insights into the role of heterogeneities on the sensitivity of the explosives through shock input-to-run distance relationships (Pop-plots), and reactive chemistry growth in and behind the incident shock front. By logically mapping out these relationships, the data provide a scientific foundation for the development of predictive capabilities for modeling new formulations, and designing next-generation energetic materials.

Alma Polarization Observations Of The Particle Accelerators In The Peculiar Hot Spot 3C 445 South

NASA Astrophysics Data System (ADS)

Orienti, Monica; Brunetti, G.; Mack, K.-H.; Nagai, H.; Paladino, R.; Prieto, M. A.

2017-10-01

Radio hot spots are bright and compact regions at the edges of powerful radio galaxies. In these regions the relativistic particles are reaccelerated by shocks produced by the interaction between the supersonic jets and the external environment. The discovery of synchrotron optical emission extending on kpc scale in some hot spots suggests that additional efficient and spatially distributed acceleration mechanisms must take place in order to compensate the severe radiative losses of optical emitting electrons. The key parameter to unveil the mechanism at work is the polarization intensity: high fractional polarization in the case of shocks, whereas low values or absence of polarization are expected in case of turbulence. In this contribution I will present results on full-polarization ALMA observations at 97 GHz of the hot spot 3C 445 South. This arc-shaped hot spot is characterized by two main components enshrouded by extended emission that is visible from radio to X-rays. The ALMA results, complemented by mutiband VLA, VLT, HST and Chandra data, will be used to shed a light on the complex distribution and nature of particle acceleration at the edge of powerful radio galaxies.

Alcohol-related hot-spot analysis and prediction : final report.

DOT National Transportation Integrated Search

2017-05-01

This project developed methods to more accurately identify alcohol-related crash hot spots, ultimately allowing for more effective and efficient enforcement and safety campaigns. Advancements in accuracy came from improving the calculation of spatial...

The Nature, Number and Evolution of Hot-Spots in Ammonium Nitrate

NASA Astrophysics Data System (ADS)

Proud, W. G.; Kirby, I. J.; Field, J. E.

2004-07-01

Ammonium nitrate (AN) is a commonly used fertiliser and also one component of the most widely used explosive in the world AN: Fuel Oil mixtures. This study uses a combination of high-speed photography, UV/Visible spectroscopy and modelling. By using thin beds, <0.5 mm thick, with a porosity of 22%vol the number and evolution of hot-spots in ammonium nitrate are monitored directly under dynamic loading conditions. The critical conditions for ignition are defined in terms of energy localisation mechanisms, temperature rise and inter-communication between the hot-spots.

3D plasmonic nanoarchitectures for extreme light concentration

NASA Astrophysics Data System (ADS)

Arnob, Md Masud Parvez; Zhao, Fusheng; Shih, Wei-Chuan

2017-08-01

Plasmonic nanomaterials are known to concentrate incident light to their surfaces by collective electron oscillation. Plasmonic hot-spot refers to locations where electromagnetic fields are particularly enhanced relative to the incident field. Traditional plasmonic nanomaterials are 1D (e.g., colloidal nanoparticles) or 2D (lithographically patterned nanostructure arrays) in nature, which typically result in sparse field concentration patterns. To improve efficiency and better utilization of hot-spots, we investigate 3D plasmonic nanoarchitecture where abundant hot-spots are formed in a 3D volumetric fashion, a feature drastically departing from traditional nanostructures.

Io hot spots - Infrared photometry of satellite occultations

NASA Technical Reports Server (NTRS)

Goguen, J. D.; Matson, D. L.; Sinton, W. M.; Howell, R. R.; Dyck, H. M.

1988-01-01

Io's active hot spots, which are presently mapped on the basis of IR photometry of this moon's occultation by other Gallilean satellites, are obtained with greatest spatial resolution near the sub-earth point. A model is developed for the occultation lightcurves, and its fitting to the data defines the apparent path of the occulting satellite relative to Io; the mean error in apparent relative position of occulting satellites is of the order of 178 km. A heretofore unknown, 20-km diameter hot spot is noted on Io's leading hemisphere.

Disturbance Impacts on Thermal Hot Spots and Hot Moments at the Peatland-Atmosphere Interface

NASA Astrophysics Data System (ADS)

Leonard, R. M.; Kettridge, N.; Devito, K. J.; Petrone, R. M.; Mendoza, C. A.; Waddington, J. M.; Krause, S.

2018-01-01

Soil-surface temperature acts as a master variable driving nonlinear terrestrial ecohydrological, biogeochemical, and micrometeorological processes, inducing short-lived or spatially isolated extremes across heterogeneous landscape surfaces. However, subcanopy soil-surface temperatures have been, to date, characterized through isolated, spatially discrete measurements. Using spatially complex forested northern peatlands as an exemplar ecosystem, we explore the high-resolution spatiotemporal thermal behavior of this critical interface and its response to disturbances by using Fiber-Optic Distributed Temperature Sensing. Soil-surface thermal patterning was identified from 1.9 million temperature measurements under undisturbed, trees removed and vascular subcanopy removed conditions. Removing layers of the structurally diverse vegetation canopy not only increased mean temperatures but it shifted the spatial and temporal distribution, range, and longevity of thermal hot spots and hot moments. We argue that linking hot spots and/or hot moments with spatially variable ecosystem processes and feedbacks is key for predicting ecosystem function and resilience.

78 FR 46298 - Airworthiness Directives; Fokker Services B.V. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-31

... above, this [EASA] AD requires the installation of fuses in the Max Level sensor wiring and subsequently..., which revealed that under certain failure conditions of the maximum level (Max Level) sensor wiring, a short circuit may develop that causes a hot spot on the wiring conduit, or puncturing of the wiring...

Fatigue analysis of the bow structure of FPSO

NASA Astrophysics Data System (ADS)

Hu, Zhi-Qiang; Gao, Zhen; Gu, Yong-Ning

2003-06-01

The bow structure of FPSO moored by the single mooring system is rather complicated. There are many potential hot spots in connection parts of structures between the mooring support frame and the forecastle. Mooring forces, which are induced by wave excitation and transferred by the YOKE and the mooring support frame, may cause fatigue damage to the bow structure. Different from direct wave-induced-forces, the mooring force consists of wave frequency force (WF) and 2nd draft low frequency force (LF)[3], which are represented by two sets of short-term distribution respectively. Based on two sets of short-term distribution of mooring forces obtained by the model test, the fatigue damage of the bow structure of FPSO is analyzed, with emphasis on two points. One is the procedure and position selection for fatigue check, and the other is the application of new formulae for the calculation of accumulative fatigue damage caused by two sets of short-term distribution of hot spot stress range. From the results distinguished features of fatigue damage to the FPSO’s bow structure can be observed.

Hydrodynamic scaling of the deceleration-phase Rayleigh–Taylor instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, A., E-mail: abos@lle.rochester.edu; Woo, K. M.; Betti, R.

2015-07-15

The scaling of the deceleration phase of inertial fusion direct-drive implosions is investigated for OMEGA and National Ignition Facility (NIF)-size targets. It is shown that the deceleration-phase Rayleigh–Taylor instability (RTI) does not scale hydro-equivalently with implosion size. This is because ablative stabilization resulting from thermal conduction and radiation transport in a spherically converging geometry is different on the two scales. As a consequence, NIF-scale implosions show lower hot-spot density and mass ablation velocity, allowing for higher RTI growth. On the contrary, stabilization resulting from density-gradient enhancement, caused by reabsorption of radiation emitted from the hot spot, is higher on NIFmore » implosions. Since the RTI mitigation related to thermal conduction and radiation transport scale oppositely with implosion size, the degradation of implosion performance caused by the deceleration RTI is similar for NIF and OMEGA targets. It is found that a minimum threshold for the no-α Lawson ignition parameter of χ{sub Ω} ≈ 0.2 at the OMEGA scale is required to demonstrate hydro-equivalent ignition at the NIF scale for symmetric direct-drive implosions.« less

Hydrodynamic scaling of the deceleration-phase Rayleigh–Taylor instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, A.; Woo, K. M.; Nora, R.

2015-07-02

The scaling of the deceleration phase of inertial fusion direct-drive implosions is investigated for OMEGA and National Ignition Facility (NIF)-size targets. It is shown that the deceleration-phase Rayleigh–Taylor instability (RTI) does not scale hydro-equivalently with implosion size. This is because ablative stabilization resulting from thermal conduction and radiation transport in a spherically converging geometry is different on the two scales. As a consequence, NIF-scale implosions show lower hot-spot density and mass ablation velocity, allowing for higher RTI growth. On the contrary, stabilization resulting from density-gradient enhancement, caused by reabsorption of radiation emitted from the hot spot, is higher on NIFmore » implosions. Since the RTI mitigation related to thermal conduction and radiation transport scale oppositely with implosion size, the degradation of implosion performance caused by the deceleration RTI is similar for NIF and OMEGA targets. It is found that a minimum threshold for the no-α Lawson ignition parameter of ΧΩ ≈ 0.2 at the OMEGA scale is required to demonstrate hydro-equivalent ignition at the NIF scale for symmetric direct-drive implosions.« less

Prediction of hot spot residues at protein-protein interfaces by combining machine learning and energy-based methods.

PubMed

Lise, Stefano; Archambeau, Cedric; Pontil, Massimiliano; Jones, David T

2009-10-30

Alanine scanning mutagenesis is a powerful experimental methodology for investigating the structural and energetic characteristics of protein complexes. Individual amino-acids are systematically mutated to alanine and changes in free energy of binding (DeltaDeltaG) measured. Several experiments have shown that protein-protein interactions are critically dependent on just a few residues ("hot spots") at the interface. Hot spots make a dominant contribution to the free energy of binding and if mutated they can disrupt the interaction. As mutagenesis studies require significant experimental efforts, there is a need for accurate and reliable computational methods. Such methods would also add to our understanding of the determinants of affinity and specificity in protein-protein recognition. We present a novel computational strategy to identify hot spot residues, given the structure of a complex. We consider the basic energetic terms that contribute to hot spot interactions, i.e. van der Waals potentials, solvation energy, hydrogen bonds and Coulomb electrostatics. We treat them as input features and use machine learning algorithms such as Support Vector Machines and Gaussian Processes to optimally combine and integrate them, based on a set of training examples of alanine mutations. We show that our approach is effective in predicting hot spots and it compares favourably to other available methods. In particular we find the best performances using Transductive Support Vector Machines, a semi-supervised learning scheme. When hot spots are defined as those residues for which DeltaDeltaG >or= 2 kcal/mol, our method achieves a precision and a recall respectively of 56% and 65%. We have developed an hybrid scheme in which energy terms are used as input features of machine learning models. This strategy combines the strengths of machine learning and energy-based methods. Although so far these two types of approaches have mainly been applied separately to biomolecular problems, the results of our investigation indicate that there are substantial benefits to be gained by their integration.

Assessing Statistically Significant Heavy-Metal Concentrations in Abandoned Mine Areas via Hot Spot Analysis of Portable XRF Data

PubMed Central

Kim, Sung-Min; Choi, Yosoon

2017-01-01

To develop appropriate measures to prevent soil contamination in abandoned mining areas, an understanding of the spatial variation of the potentially toxic trace elements (PTEs) in the soil is necessary. For the purpose of effective soil sampling, this study uses hot spot analysis, which calculates a z-score based on the Getis-Ord Gi* statistic to identify a statistically significant hot spot sample. To constitute a statistically significant hot spot, a feature with a high value should also be surrounded by other features with high values. Using relatively cost- and time-effective portable X-ray fluorescence (PXRF) analysis, sufficient input data are acquired from the Busan abandoned mine and used for hot spot analysis. To calibrate the PXRF data, which have a relatively low accuracy, the PXRF analysis data are transformed using the inductively coupled plasma atomic emission spectrometry (ICP-AES) data. The transformed PXRF data of the Busan abandoned mine are classified into four groups according to their normalized content and z-scores: high content with a high z-score (HH), high content with a low z-score (HL), low content with a high z-score (LH), and low content with a low z-score (LL). The HL and LH cases may be due to measurement errors. Additional or complementary surveys are required for the areas surrounding these suspect samples or for significant hot spot areas. The soil sampling is conducted according to a four-phase procedure in which the hot spot analysis and proposed group classification method are employed to support the development of a sampling plan for the following phase. Overall, 30, 50, 80, and 100 samples are investigated and analyzed in phases 1–4, respectively. The method implemented in this case study may be utilized in the field for the assessment of statistically significant soil contamination and the identification of areas for which an additional survey is required. PMID:28629168

Assessing Statistically Significant Heavy-Metal Concentrations in Abandoned Mine Areas via Hot Spot Analysis of Portable XRF Data.

PubMed

Kim, Sung-Min; Choi, Yosoon

2017-06-18

To develop appropriate measures to prevent soil contamination in abandoned mining areas, an understanding of the spatial variation of the potentially toxic trace elements (PTEs) in the soil is necessary. For the purpose of effective soil sampling, this study uses hot spot analysis, which calculates a z -score based on the Getis-Ord Gi* statistic to identify a statistically significant hot spot sample. To constitute a statistically significant hot spot, a feature with a high value should also be surrounded by other features with high values. Using relatively cost- and time-effective portable X-ray fluorescence (PXRF) analysis, sufficient input data are acquired from the Busan abandoned mine and used for hot spot analysis. To calibrate the PXRF data, which have a relatively low accuracy, the PXRF analysis data are transformed using the inductively coupled plasma atomic emission spectrometry (ICP-AES) data. The transformed PXRF data of the Busan abandoned mine are classified into four groups according to their normalized content and z -scores: high content with a high z -score (HH), high content with a low z -score (HL), low content with a high z -score (LH), and low content with a low z -score (LL). The HL and LH cases may be due to measurement errors. Additional or complementary surveys are required for the areas surrounding these suspect samples or for significant hot spot areas. The soil sampling is conducted according to a four-phase procedure in which the hot spot analysis and proposed group classification method are employed to support the development of a sampling plan for the following phase. Overall, 30, 50, 80, and 100 samples are investigated and analyzed in phases 1-4, respectively. The method implemented in this case study may be utilized in the field for the assessment of statistically significant soil contamination and the identification of areas for which an additional survey is required.

Transportation conformity particulate matter hot-spot air quality modeling.

DOT National Transportation Integrated Search

2013-07-01

In light of the new development in particulate matter (PM) hot-spot regulations and Illinois Department : of Transportation (IDOT)s National Environmental Policy Act (NEPA) documentation requirements, : this project is intended to (1) perform and ...

A New Hot Spot on Northern Io

NASA Image and Video Library

2001-12-10

In August 2001, NASA Galileo spacecraft has returned imagery of a hot spot on Jupiter moon Io that was the source of a towering plume indicating a sulfur-dioxide concentration that may have been fallout from the plume.

Visualization of hot spot formation in energetic materials under periodic mechanical excitation using phosphor thermography

NASA Astrophysics Data System (ADS)

Casey, Alex; Fenoglio, Gabriel; Detrinidad, Humberto

2017-06-01

Under mechanical excitation, energy is known to localize within an energetic material resulting in `hot spot' formation. While many formation mechanisms have been proposed, additional insight to heat generation mechanisms, the effect of binder/crystal interfaces, and predication capabilities can be gained by quantifying the initiation and growth of the hot spots. Phosphor thermography is a well established temperature sensing technique wherein an object's temperature is obtained by collecting the temperature dependent luminescence of an optically excited phosphor. Herein, the phosphor thermography technique has been applied to Dow Corning Sylgard® 184/octahydro 1,3,5,7 tetranitro 1,3,5,7 tetrazocine (HMX) composite materials under mechanical excitation in order to visualize the evolution of the temperature field, and thus hot spot formation, within the binder. Funded by AFOSR. Supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

Measurements of an ablator-gas atomic mix in indirectly driven implosions at the National Ignition Facility.

PubMed

Smalyuk, V A; Tipton, R E; Pino, J E; Casey, D T; Grim, G P; Remington, B A; Rowley, D P; Weber, S V; Barrios, M; Benedetti, L R; Bleuel, D L; Bradley, D K; Caggiano, J A; Callahan, D A; Cerjan, C J; Clark, D S; Edgell, D H; Edwards, M J; Frenje, J A; Gatu-Johnson, M; Glebov, V Y; Glenn, S; Haan, S W; Hamza, A; Hatarik, R; Hsing, W W; Izumi, N; Khan, S; Kilkenny, J D; Kline, J; Knauer, J; Landen, O L; Ma, T; McNaney, J M; Mintz, M; Moore, A; Nikroo, A; Pak, A; Parham, T; Petrasso, R; Sayre, D B; Schneider, M B; Tommasini, R; Town, R P; Widmann, K; Wilson, D C; Yeamans, C B

2014-01-17

We present the first results from an experimental campaign to measure the atomic ablator-gas mix in the deceleration phase of gas-filled capsule implosions on the National Ignition Facility. Plastic capsules containing CD layers were filled with tritium gas; as the reactants are initially separated, DT fusion yield provides a direct measure of the atomic mix of ablator into the hot spot gas. Capsules were imploded with x rays generated in hohlraums with peak radiation temperatures of ∼294  eV. While the TT fusion reaction probes conditions in the central part (core) of the implosion hot spot, the DT reaction probes a mixed region on the outer part of the hot spot near the ablator-hot-spot interface. Experimental data were used to develop and validate the atomic-mix model used in two-dimensional simulations.

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

NASA Astrophysics Data System (ADS)

Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; Sangster, T. C.; Betti, R.; Bose, A.; Boehly, T. R.; Bonino, M. J.; Campbell, E. M.; Cao, D.; Collins, T. J. B.; Craxton, R. S.; Davis, A. K.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu Johnson, M.; Glebov, V. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Jacobs-Perkins, D.; Janezic, R.; Karasik, M.; Keck, R. L.; Kelly, J. H.; Kessler, T. J.; Knauer, J. P.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Obenschain, S. P.; Petrasso, R. D.; Radha, P. B.; Rice, B.; Rosenberg, M. J.; Schmitt, A. J.; Schmitt, M. J.; Seka, W.; Shmayda, W. T.; Shoup, M. J.; Shvydky, A.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Theobald, W.; Ulreich, J.; Wittman, M. D.; Woo, K. M.; Yaakobi, B.; Zuegel, J. D.

2016-07-01

A record fuel hot-spot pressure Phs=56 ±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ˜60 % of the value required for ignition [A. Bose et al., Phys. Rev. E 93, LM15119ER (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

Demonstration of fuel hot-spot pressure in excess of 50 Gbar for direct-drive, layered deuterium-tritium implosions on OMEGA

DOE PAGES

Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; ...

2016-07-07

A record fuel hot-spot pressure P hs = 56±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium–tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility (NIF), these implosions achieved a Lawson parameter ~60% of the value required for ignition [A. Bose et al., Phys. Rev. E (in press)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure ismore » ~40% lower. Furthermore, three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.« less

Demonstration of fuel hot-spot pressure in excess of 50 Gbar for direct-drive, layered deuterium-tritium implosions on OMEGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.

A record fuel hot-spot pressure P hs = 56±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium–tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility (NIF), these implosions achieved a Lawson parameter ~60% of the value required for ignition [A. Bose et al., Phys. Rev. E (in press)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure ismore » ~40% lower. Furthermore, three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.« less

Multiphysics Simulations of Hot-Spot Initiation in Shocked Insensitive High-Explosive

NASA Astrophysics Data System (ADS)

Najjar, Fady; Howard, W. M.; Fried, L. E.

2010-11-01

Solid plastic-bonded high-explosive materials consist of crystals with micron-sized pores embedded. Under mechanical or thermal insults, these voids increase the ease of shock initiation by generating high-temperature regions during their collapse that might lead to ignition. Understanding the mechanisms of hot-spot initiation has significant research interest due to safety, reliability and development of new insensitive munitions. Multi-dimensional high-resolution meso-scale simulations are performed using the multiphysics software, ALE3D, to understand the hot-spot initiation. The Cheetah code is coupled to ALE3D, creating multi-dimensional sparse tables for the HE properties. The reaction rates were obtained from MD Quantum computations. Our current predictions showcase several interesting features regarding hot spot dynamics including the formation of a "secondary" jet. We will discuss the results obtained with hydro-thermo-chemical processes leading to ignition growth for various pore sizes and different shock pressures.

In Situ Hot-Spot Assembly as a General Strategy for Probing Single Biomolecules.

PubMed

Liu, Huiqiao; Li, Qiang; Li, Mingmin; Ma, Sisi; Liu, Dingbin

2017-05-02

Single-molecule detection using surface-enhanced Raman spectroscopy (SERS) has attracted increasing attention in chemical and biomedical analysis. However, it remains a major challenge to probe single biomolecules by means of SERS hot spots owing to the small volume of hot spots and their random distribution on substrates. We here report an in situ hot-spot assembly method as a general strategy for probing single biomolecules. As a proof-of-concept, this proposed strategy was successfully used for the detection of single microRNA-21 (miRNA-21, a potential cancer biomarker) at the single-cell level, showing great capability in differentiating the expression of miRNA-21 in single cancer cells from normal cells. This approach was further extended to single-protein detection. The versatility of the strategy opens an exciting avenue for single-molecule detection of biomarkers of interest and thus holds great promise in a variety of biological and biomedical applications.

Monte Carlo tests of the ELIPGRID-PC algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, J.R.

1995-04-01

The standard tool for calculating the probability of detecting pockets of contamination called hot spots has been the ELIPGRID computer code of Singer and Wickman. The ELIPGRID-PC program has recently made this algorithm available for an IBM{reg_sign} PC. However, no known independent validation of the ELIPGRID algorithm exists. This document describes a Monte Carlo simulation-based validation of a modified version of the ELIPGRID-PC code. The modified ELIPGRID-PC code is shown to match Monte Carlo-calculated hot-spot detection probabilities to within {plus_minus}0.5% for 319 out of 320 test cases. The one exception, a very thin elliptical hot spot located within a rectangularmore » sampling grid, differed from the Monte Carlo-calculated probability by about 1%. These results provide confidence in the ability of the modified ELIPGRID-PC code to accurately predict hot-spot detection probabilities within an acceptable range of error.« less

Compressible Heating in the Condense Phase due to Pore Collapse in HMX

NASA Astrophysics Data System (ADS)

Zhang, Ju; Jackson, Thomas

Axisymmetric pore collapse in HMX is studied numerically by solving multi-phase reactive Euler equations. The generation of hot spots in the condense phase due to compressible heating is examined. The motivation is to improve the understanding of the role of embedded cavities in the initiation of reaction in explosives, and to investigate the effect of hot spots in the condense phase due to compressible heating alone, complementing previous study on hot spots due to the reaction in the gas phase and at the interface. It is found that the shock-cavity interaction results in pressures and thus temperatures that are substantially higher than the post-shock values in the condense phase. However, these hot spots in the condense phase due to compressible heating alone do not seem to be sufficiently hot to lead to ignition at shock pressures of 1-3 GPa. Thus, compressible heating in the condense phase may be excluded as a mechanism for initiation of explosives. It should be pointed out that the ignition threshold for the temperature, the so-called ``switch-on'' temperature, of hot spots depend on chemistry kinetics parameters. Switch-on temperature is lower for faster reaction rate. The current chemistry kinetics parameters are based on previous experimental work. This work was supported in part by the Defense Threat Reduction Agency and by the U.S. Department of Energy.

A recombination hot spot in HIV-1 contains guanosine runs that can form a G-quartet structure and promote strand transfer in vitro.

PubMed

Shen, Wen; Gao, Lu; Balakrishnan, Mini; Bambara, Robert A

2009-12-04

The co-packaged RNA genomes of human immunodeficiency virus-1 recombine at a high rate. Recombination can mix mutations to generate viruses that escape immune response. A cell-culture-based system was designed previously to map recombination events in a 459-bp region spanning the primer binding site through a portion of the gag protein coding region. Strikingly, a strong preferential site for recombination in vivo was identified within a 112-nucleotide-long region near the beginning of gag. Strand transfer assays in vitro revealed that three pause bands in the gag hot spot each corresponded to a run of guanosine (G) residues. Pausing of reverse transcriptase is known to promote recombination by strand transfer both in vivo and in vitro. To assess the significance of the G runs, we altered them by base substitutions. Disruption of the G runs eliminated both the associated pausing and strand transfer. Some G-rich sequences can develop G-quartet structures, which were first proposed to form in telomeric DNA. G-quartet structure formation is highly dependent on the presence of specific cations. Incubation in cations discouraging G-quartets altered gel mobility of the gag template consistent with breakdown of G-quartet structure. The same cations faded G-run pauses but did not affect pauses caused by hairpins, indicating that quartet structure causes pausing. Moreover, gel analysis with cations favoring G-quartet structure indicated no structure in mutated templates. Overall, results point to reverse transcriptase pausing at G runs that can form quartets as a unique feature of the gag recombination hot spot.

Hot spot analysis for driving the development of hits into leads in fragment based drug discovery

PubMed Central

Hall, David R.; Ngan, Chi Ho; Zerbe, Brandon S.; Kozakov, Dima; Vajda, Sandor

2011-01-01

Fragment based drug design (FBDD) starts with finding fragment-sized compounds that are highly ligand efficient and can serve as a core moiety for developing high affinity leads. Although the core-bound structure of a protein facilitates the construction of leads, effective design is far from straightforward. We show that protein mapping, a computational method developed to find binding hot spots and implemented as the FTMap server, provides information that complements the fragment screening results and can drive the evolution of core fragments into larger leads with a minimal loss or, in some cases, even a gain in ligand efficiency. The method places small molecular probes, the size of organic solvents, on a dense grid around the protein, and identifies the hot spots as consensus clusters formed by clusters of several probes. The hot spots are ranked based on the number of probe clusters, which predicts the binding propensity of the subsites and hence their importance for drug design. Accordingly, with a single exception the main hot spot identified by FTMap binds the core compound found by fragment screening. The most useful information is provided by the neighboring secondary hot spots, indicating the regions where the core can be extended to increase its affinity. To quantify this information, we calculate the density of probes from mapping, which describes the binding propensity at each point, and show that the change in the correlation between a ligand position and the probe density upon extending or repositioning the core moiety predicts the expected change in ligand efficiency. PMID:22145575

Extracting Hot spots of Topics from Time Stamped Documents

PubMed Central

Chen, Wei; Chundi, Parvathi

2011-01-01

Identifying time periods with a burst of activities related to a topic has been an important problem in analyzing time-stamped documents. In this paper, we propose an approach to extract a hot spot of a given topic in a time-stamped document set. Topics can be basic, containing a simple list of keywords, or complex. Logical relationships such as and, or, and not are used to build complex topics from basic topics. A concept of presence measure of a topic based on fuzzy set theory is introduced to compute the amount of information related to the topic in the document set. Each interval in the time period of the document set is associated with a numeric value which we call the discrepancy score. A high discrepancy score indicates that the documents in the time interval are more focused on the topic than those outside of the time interval. A hot spot of a given topic is defined as a time interval with the highest discrepancy score. We first describe a naive implementation for extracting hot spots. We then construct an algorithm called EHE (Efficient Hot Spot Extraction) using several efficient strategies to improve performance. We also introduce the notion of a topic DAG to facilitate an efficient computation of presence measures of complex topics. The proposed approach is illustrated by several experiments on a subset of the TDT-Pilot Corpus and DBLP conference data set. The experiments show that the proposed EHE algorithm significantly outperforms the naive one, and the extracted hot spots of given topics are meaningful. PMID:21765568

The Northern Appalachian Anomaly: A modern asthenospheric upwelling

NASA Astrophysics Data System (ADS)

Menke, William; Skryzalin, Peter; Levin, Vadim; Harper, Thomas; Darbyshire, Fiona; Dong, Ted

2016-10-01

The Northern Appalachian Anomaly (NAA) is an intense, laterally localized (400 km diameter) low-velocity anomaly centered in the asthenosphere beneath southern New England. Its maximum shear velocity contrast, at 200 km depth, is about 10%, and its compressional-to-shear velocity perturbation ratio is about unity, values compatible with it being a modern thermal anomaly. Although centered close to the track of the Great Meteor hot spot, it is not elongated parallel to it and does not crosscut the cratonic margin. In contrast to previous explanations, we argue that the NAA's spatial association with the hot spot track is coincidental and that it is caused by small-scale upwelling associated with an eddy in the asthenospheric flow field at the continental margin. That the NAA is just one of several low-velocity features along the eastern margin of North America suggests that this process may be globally ubiquitous.

Nonlinear dynamics of a vapor bubble expanding in a superheated region of finite size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Annenkova, E. A., E-mail: a-a-annenkova@yandex.ru; Kreider, W.; Sapozhnikov, O. A.

2015-10-28

Growth of a vapor bubble in a superheated liquid is studied theoretically. Contrary to the typical situation of boiling, when bubbles grow in a uniformly heated liquid, here the superheated region is considered in the form of a millimeter-sized spherical hot spot. An initial micron-sized bubble is positioned at the hot spot center and a theoretical model is developed that is capable of studying bubble growth caused by vapor pressure inside the bubble and corresponding hydrodynamic and thermal processes in the surrounding liquid. Such a situation is relevant to the dynamics of vapor cavities that are created in soft biologicalmore » tissue in the focal region of a high-intensity focused ultrasound beam with a shocked pressure waveform. Such beams are used in the recently proposed treatment called boiling histotripsy. Knowing the typical behavior of vapor cavities during boiling histotripsy could help to optimize the therapeutic procedure.« less

Study on the effect of sink moving trajectory on wireless sensor networks

NASA Astrophysics Data System (ADS)

Zhong, Peijun; Ruan, Feng

2018-03-01

Wireless sensor networks are developing very fast in recent years, due to their wide potential applications. However there exists the so-called hot spot problem, namely the nodes close to static sink node tend to die earlier than other nodes since they have heavier burden to forward. The introduction of mobile sink node can effectively alleviate this problem since sink node can move along certain trajectories, causing hot spot nodes more evenly distributed. In this paper, we make extensive experimental simulations for circular sensor network, with one mobile sink moving along different radius circumference. The whole network is divided into several clusters and there is one cluster head (CH) inside each cluster. The ordinary sensors communicate with CH and CHs construct a chain until the sink node. Simulation results show that the best network performance appears when sink moves along 0.25 R in terms of network lifetime.

A connection between mix and adiabat in ICF capsules

NASA Astrophysics Data System (ADS)

Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Yi, Sunghuan (Austin); Batha, Steven

2016-10-01

We study the relationship between instability induced mix, preheat and the adiabat of the deuterium-tritium (DT) fuel in fusion capsule experiments. Our studies show that hydrodynamic instability not only directly affects the implosion, hot spot shape and mix, but also affects the thermodynamics of the capsule, such as, the adiabat of the DT fuel, and, in turn, affects the energy partition between the pusher shell (cold DT) and the hot spot. It was found that the adiabat of the DT fuel is sensitive to the amount of mix caused by Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities at the material interfaces due to its exponential dependence on the fuel entropy. An upper limit of mix allowed maintaining a low adiabat of DT fuel is derived. Additionally we demonstrated that the use of a high adiabat for the DT fuel in theoretical analysis and with the aid of 1D code simulations could explain some aspects of the 3D effects and mix in the capsule experiments. Furthermore, from the observed neutron images and our physics model, we could infer the adiabat of the DT fuel in the capsule and determine the possible amount of mix in the hot spot (LA-UR-16-24880). This work was conducted under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.

Advanced operations focused on connected vehicles/infrastructure (CVI-UTC).

DOT National Transportation Integrated Search

2015-12-01

The goal of the Infrastructure Safety Assessment in a Connected Vehicle (CV) Environment : project was to develop a method to identify infrastructure safety hot spots using CV data. : Using these basic safety messages to detect hot spots may al...

Use of roadway attributes in hot spot identification and analysis.

DOT National Transportation Integrated Search

2015-10-01

This research focuses on the addition of roadway attributes in the selection and analysis of hot spots. This : is in conjunction with the framework for highway safety mitigation in Utah with its six primary steps: network : screening, diagnosis...

High-resolution observations of radio-source hot spots at 329 MHz

NASA Technical Reports Server (NTRS)

Linfield, R.; Simon, R. S.

1984-01-01

The hot spots of several luminous double radio sources have been observed at 329 MHz with VLBI at fringe spacings ranging from 0.05 to 0.70 arcsec. Two out of two high-redshift (z = about 0.5) sources, but only one of six low-redshift (z = about 0.05) sources, were detected. For the low-redshift source (3C 234) which was detected, either the hot spot is larger at 329 MHz than at 15 GHz, or else the brightness contrast between it and the surrounding lobe is lower at the lower frequency.

Jovian longitudinal asymmetry in Io-related and Europa-related auroral hot spots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dessler, A.J.; Chamberlain, J.W.

1979-06-15

Jupiter's internal magnetic field is markedly non-dipolar. We propose that Io- or Europa-generated auroral emissions (originating at the foot of either Io's or Europa's magnetic flux tube) are largely restricted to longitudes where Jupiter's ionospheric conductivity is enhanced. Trapped, energetic electrons that drift into Jupiter's atmosphere, in regions where the Jovian magnetic field is anomalously weak, produce the increased conductivity. The longitude range of enchanced auroral hot-spot emissions is thus restricted to an active sector that is determined from dekametric radio emission to lie in the northern hemisphere in the Jovian System III (1965) longitude range of 205/sup 0/ +-more » 30/sup 0/. Relatively weaker auroral hot spots should occur in the southern hemisphere along the mgnetic conjugate trace covering the longitude range of 215/sup 0/ +- 55/sup 0/. At other longitudes, the brightness of the hot spot should decrease by at least one order of magnitude. These results, with respect to both brightness and longitude, are in accord with the observations of Jovian auroral hot spots reported by Atreya et al. We show that the northern hemisphere foot of either Io's or Europa's magnetic flux tube was in the preferred longitude range (the active sector) at the time of each observation.« less

Dramatic reduction of sulfur dioxide emission in Northeastern China in the last decade

NASA Astrophysics Data System (ADS)

Yuan, J.

2017-12-01

Analysis of spatial and temporal variations of sulfur dioxide concentration in planetary boundary layer were conducted. The data were generated by NASA satellite daily from October of 2004 and were obtained through NASA Giovanni. The global monthly mean spatial distribution of sulfur dioxide showed several hot spots including: several spots on some islands in the Pacific Ocean, several spots in central America, and central Africa. Most of these hot spots of sulfur dioxide are related to known active volcanos. The biggest hot spot of sulfur dioxide were observed in Northeastern China. While high concentration sulfur dioxide was still observed in Northeastern China in 2017. The area averaged concentration of sulfur dioxide declined dramatically since its peak in 2008. This temporal trend indicates that sulfur reduction effort has been effective in the last decade or post 2008 financial crisis recovery lead an industry less sulfur dioxide emission.

Petrological systematics of mid-ocean ridge basalts: Constraints on melt generation beneath ocean ridges

NASA Astrophysics Data System (ADS)

Langmuir, Charles H.; Klein, Emily M.; Plank, Terry

Mid-ocean ridge basalts (MORB) are a consequence of pressure-release melting beneath ocean ridges, and contain much information concerning melt formation, melt migration and heterogeneity within the upper mantle. MORB major element chemical systematics can be divided into global and local aspects, once they have been corrected for low pressure fractionation and interlaboratory biases. Regional average compositions for ridges unaffected by hot spots ("normal" ridges) can be used to define the global correlations among normalized Na2O, FeO, TiO2 and SiO2 contents, CaO/Al2O3 ratios, axial depth and crustal thickness. Back-arc basins show similar correlations, but are offset to lower FeO and TiO2 contents. Some hot spots, such as the Azores and Galapagos, disrupt the systematics of nearby ridges and have the opposite relationships between FeO, Na2O and depth over distances of 1000 km. Local variations in basalt chemistry from slow- and fast-spreading ridges are distinct from one another. On slow-spreading ridges, correlations among the elements cross the global vector of variability at a high angle. On the fast-spreading East Pacific Rise (EPR), correlations among the elements are distinct from both global and slow-spreading compositional vectors, and involve two components of variation. Spreading rate does not control the global correlations, but influences the standard deviations of axial depth, crustal thickness, and MgO contents of basalts. Global correlations are not found in very incompatible trace elements, even for samples far from hot spots. Moderately compatible trace elements for normal ridges, however, correlate with the major elements. Trace element systematics are significantly different for the EPR and the mid-Atlantic Ridge (MAR). Normal portions of the MAR are very depleted in REE, with little variability; hot spots cause large long wavelength variations in REE abundances. Normal EPR basalts are significantly more enriched than MAR basalts from normal ridges, and still more enriched basalts can erupt sporadically along the entire length of the EPR. This leads to very different histograms of distribution for the data sets as a whole, and a very different distribution of chemistry along strike for the two ridges. Despite these differences, the mean Ce/Sm ratios from the two ridges are identical. Existing methods for calculating the major element compositions of mantle melts [Klein and Langmuir, 1987; McKenzie and Bickle, 1988; Niu and Batiza, 1991] are critically examined. New quantitative methods for mantle melting and high pressure fractionation are developed to evaluate the chemical consequences of melting and fractionation processes and mantle heterogeneity. The new methods rely on new equations for partition coefficients for the major elements between mantle minerals and melts. The melting calculations can be used to investigate the chemical compositions produced by small extents of melting or high pressures of melting that cannot yet be determined experimentally. Application of the new models to the observations described above leads to two major conclusions: (1) The global correlations for normal ridges are caused by variations in mantle temperature, as suggested by Klein and Langmuir [1987] and not by mantle heterogeneity. (2) Local variations are caused by melting processes, but are not yet quantitatively accounted for. On slower spreading ridges, local variations are controlled by the melting regime in the mantle. On the EPR, local variations are predominantly controlled by ubiquitous, small scale heterogeneites. Volatile content may be an important and as yet undetermined factor in affecting the observed variations in major elements. We propose a hypothesis, similar to one proposed by Allegre et al [1984] for isotopic data, to explain the differences between the Atlantic and Pacific local trends, and the trace element systematics of the two ocean basins, as consequences of spreading rate and a different distribution of enriched components from hot spots in the two ocean basins. In the Atlantic, the hot spot influence is in discrete areas, and produces clear depth and chemical anomalies. Ridge segments far from hot spots do not contain enriched basalts. Melting processes associated with slow-spreading ridges vary substantially over short distances along strike and lead to the local trends discussed above, irrespective of hot spot influence. In the Pacific, enriched components appear to have been more thoroughly mixed into the mantle, leading to ubiquitous small scale heterogeneities. Melting processes do not vary appreciably along strike, so local chemical variations are dominated by the relative contribution of enriched component on short time and length scales. Thus the extent of mixing and distribution of enriched components influences strongly the contrasting local major element trends. Despite the difference in the distribution of enriched components, the mean compositions of each data set are equivalent. This suggests that the hot spot influence is similar in the two ocean basins, but its distribution in the upper mantle is different. These contrasting relationships between hot spots and ridges may result from differences in both spreading rate and tectonic history. Unrecognized hot spots may play an important role in diverse aspects of EPR volcanism, and in the chemical systematics of the erupted basalts. The observations and successful models have consequences for melt formation and segregation. (1) The melting process must be closer to fractional melting than equilibrium melting. This result is in accord with inferences from abyssal peridotites [Johnson et al., 1990]. (2) Small melt fractions generated over a range of pressures must be extracted rapidly and efficiently from high pressures within the mantle without experiencing low pressure equilibration during ascent. This requires movement in large channels, and possibly more efficient extraction mechanisms than nonnally envisaged in porous flow models with small residual porosity. (3) Diverse melts from the melting regime produce variations in basalts that are observable at the surface. (4) Basalt data can be used to constrain the melting process (e.g. active vs. passive upwelling) and its relationship to segmentation. The data cannot be used to constrain the shape of the melting regime, however, for many shapes lead to similar chemical results. (5) Highly incompatible elements and U-series disequilibria results appear not yet to be explained by melting models, and may require additional processes not yet clearly envisaged.

Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

NASA Astrophysics Data System (ADS)

Shan, Tzu-Ray; Wixom, Ryan R.; Thompson, Aidan P.

2016-08-01

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. The formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

78 FR 46303 - Airworthiness Directives; Fokker Services B.V. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-31

... above, this [EASA] AD requires the installation of fuses in the power supply wiring and/or return wiring... revealed that, under certain failure conditions, wiring in the main fuel tank could develop a short circuit that might cause a hot spot on the wiring conduit or puncture the wiring conduit wall. This proposed AD...

How to Find a Planetary Hot Spot

NASA Image and Video Library

2010-10-19

This graph of data from NASA Spitzer Space Telescope shows how astronomers located a hot spot on a distant gas planet named upsilon Andromedae b. Termed an exoplanet, it orbits a star beyond our sun, and whips around very closely to its star.

POTENTIAL AIR TOXICS HOT SPOTS IN TRUCK TERMINALS AND CABS

EPA Science Inventory

All three types of testing sites — upwind and downwind traffic — met the established definition for a hot spot by having periods with concentrations of pollutants that exceeded the EPA’s screening values. Most frequently, the pollutants with concentrations...

Co-Occurring Atomic Contacts for the Characterization of Protein Binding Hot Spots.

PubMed

Liu, Qian; Ren, Jing; Song, Jiangning; Li, Jinyan

2015-01-01

A binding hot spot is a small area at a protein-protein interface that can make significant contribution to binding free energy. This work investigates the substantial contribution made by some special co-occurring atomic contacts at a binding hot spot. A co-occurring atomic contact is a pair of atomic contacts that are close to each other with no more than three covalent-bond steps. We found that two kinds of co-occurring atomic contacts can play an important part in the accurate prediction of binding hot spot residues. One is the co-occurrence of two nearby hydrogen bonds. For example, mutations of any residue in a hydrogen bond network consisting of multiple co-occurring hydrogen bonds could disrupt the interaction considerably. The other kind of co-occurring atomic contact is the co-occurrence of a hydrophobic carbon contact and a contact between a hydrophobic carbon atom and a π ring. In fact, this co-occurrence signifies the collective effect of hydrophobic contacts. We also found that the B-factor measurements of several specific groups of amino acids are useful for the prediction of hot spots. Taking the B-factor, individual atomic contacts and the co-occurring contacts as features, we developed a new prediction method and thoroughly assessed its performance via cross-validation and independent dataset test. The results show that our method achieves higher prediction performance than well-known methods such as Robetta, FoldX and Hotpoint. We conclude that these contact descriptors, in particular the novel co-occurring atomic contacts, can be used to facilitate accurate and interpretable characterization of protein binding hot spots.

Co-Occurring Atomic Contacts for the Characterization of Protein Binding Hot Spots

PubMed Central

Liu, Qian; Ren, Jing; Song, Jiangning; Li, Jinyan

2015-01-01

A binding hot spot is a small area at a protein-protein interface that can make significant contribution to binding free energy. This work investigates the substantial contribution made by some special co-occurring atomic contacts at a binding hot spot. A co-occurring atomic contact is a pair of atomic contacts that are close to each other with no more than three covalent-bond steps. We found that two kinds of co-occurring atomic contacts can play an important part in the accurate prediction of binding hot spot residues. One is the co-occurrence of two nearby hydrogen bonds. For example, mutations of any residue in a hydrogen bond network consisting of multiple co-occurring hydrogen bonds could disrupt the interaction considerably. The other kind of co-occurring atomic contact is the co-occurrence of a hydrophobic carbon contact and a contact between a hydrophobic carbon atom and a π ring. In fact, this co-occurrence signifies the collective effect of hydrophobic contacts. We also found that the B-factor measurements of several specific groups of amino acids are useful for the prediction of hot spots. Taking the B-factor, individual atomic contacts and the co-occurring contacts as features, we developed a new prediction method and thoroughly assessed its performance via cross-validation and independent dataset test. The results show that our method achieves higher prediction performance than well-known methods such as Robetta, FoldX and Hotpoint. We conclude that these contact descriptors, in particular the novel co-occurring atomic contacts, can be used to facilitate accurate and interpretable characterization of protein binding hot spots. PMID:26675422

Temperature and abundances in the Jovian auroral stratosphere. 1: Ethane as a probe of the millibar region

NASA Technical Reports Server (NTRS)

Livengood, Timothy A.; Kostiuk, Theodor; Espenak, Fred

1993-01-01

We report infrared heterodyne spectroscopy (lambda/delta lambda is approximately 10(exp 6)) of C2H6 emission at 11.9 microns from the northern Jovian auroral region, in observations conducted over December 2-7, 1989. Accurately measured line shapes provide information on C2H6 abundance as well as temperature and permit retrieval of the source pressure region. Enhanced emission was observed in the longitude range approximately 150-180 deg at approximately 60 deg north latitude, approximately corresponding to the CH4 7.8 micron hot spot and the region of brightest UV aurora. Significant brightness variations were observed in the hot spot emissions on a time scale of approximately 20 hours. Analysis of the brightest hot spot spectra indicates C2H6 mole fractions of approximately (6.3-6.8) x 10(exp -6) at temperatures of approximately 182-184 K at 1 mbar, compared to mole fractions of (3.8 +/- 1.4) x 10(exp -6) averaged over spectra outside the hot spot at a temperature of approximately 172 K at the same pressure. Fixing the mole fraction to the lower limit retrieved in the quiescent (non-hot spot) region allows the temperature at 1 mbar to be as high as approximately 200 K within the hot spot. These results provide upper limits to the temperature increase near the source of the C2H6 thermal infrared emission. Combined with results from similar measurements of ethylene emission probing the approximately 10-microbar region (Kostiuk et al., this issue), altitude information on the thermal structure of the Jovian auroral stratosphere can be obtained for the first time.

A Whole-Tumor Histogram Analysis of Apparent Diffusion Coefficient Maps for Differentiating Thymic Carcinoma from Lymphoma.

PubMed

Zhang, Wei; Zhou, Yue; Xu, Xiao-Quan; Kong, Ling-Yan; Xu, Hai; Yu, Tong-Fu; Shi, Hai-Bin; Feng, Qing

2018-01-01

To assess the performance of a whole-tumor histogram analysis of apparent diffusion coefficient (ADC) maps in differentiating thymic carcinoma from lymphoma, and compare it with that of a commonly used hot-spot region-of-interest (ROI)-based ADC measurement. Diffusion weighted imaging data of 15 patients with thymic carcinoma and 13 patients with lymphoma were retrospectively collected and processed with a mono-exponential model. ADC measurements were performed by using a histogram-based and hot-spot-ROI-based approach. In the histogram-based approach, the following parameters were generated: mean ADC (ADC mean ), median ADC (ADC median ), 10th and 90th percentile of ADC (ADC 10 and ADC 90 ), kurtosis, and skewness. The difference in ADCs between thymic carcinoma and lymphoma was compared using a t test. Receiver operating characteristic analyses were conducted to determine and compare the differentiating performance of ADCs. Lymphoma demonstrated significantly lower ADC mean , ADC median , ADC 10 , ADC 90 , and hot-spot-ROI-based mean ADC than those found in thymic carcinoma (all p values < 0.05). There were no differences found in the kurtosis ( p = 0.412) and skewness ( p = 0.273). The ADC 10 demonstrated optimal differentiating performance (cut-off value, 0.403 × 10 -3 mm 2 /s; area under the receiver operating characteristic curve [AUC], 0.977; sensitivity, 92.3%; specificity, 93.3%), followed by the ADC mean , ADC median , ADC 90 , and hot-spot-ROI-based mean ADC. The AUC of ADC 10 was significantly higher than that of the hot spot ROI based ADC (0.977 vs. 0.797, p = 0.036). Compared with the commonly used hot spot ROI based ADC measurement, a histogram analysis of ADC maps can improve the differentiating performance between thymic carcinoma and lymphoma.

Active Volcanism on Io: Global Distribution and Variations in Activity

USGS Publications Warehouse

Lopes-Gautier, R.; McEwen, A.S.; Smythe, W.B.; Geissler, P.E.; Kamp, L.; Davies, A.G.; Spencer, J.R.; Keszthelyi, L.; Carlson, R.; Leader, F.E.; Mehlman, R.; Soderblom, L.

1999-01-01

Io's volcanic activity has been monitored by instruments aboard the Galileo spacecraft since June 28, 1996. We present results from observations by the near-infrared mapping spectrometer (NIMS) for the first 10 orbits of Galileo, correlate them with results from the Solid State Imaging System (SSI) and from groundbased observations, and compare them to what was known about Io's volcanic activity from observations made during the two Voyager flybys in 1979. A total of 61 active volcanic centers have been identified from Voyager, groundbased, and Galileo observations. Of these, 41 are hot spots detected by NIMS and/or SSI. Another 25 locations were identified as possible active volcanic centers, mostly on the basis of observed surface changes. Hot spots are correlated with surface colors, particularly dark and red deposits, and generally anti-correlated with white, SO2-rich areas. Surface features corresponding to the hot spots, mostly calderas or flows, were identified from Galileo and Voyager images. Hot spot temperatures obtained from both NIMS and SSI are consistent with silicate volcanism, which appears to be widespread on Io. Two types of hot spot activity are present: persistent-type activity, lasting from months to years, and sporadic events, which may represent either short-lived activity or low-level activity that occasionally flares up. Sporadic events are not often detected, but may make an important contribution to Io's heat flow and resurfacing. The distribution of active volcanic centers on the surface does not show any clear correlation with latitude, longitude, Voyager-derived global topography, or heat flow patterns predicted by the asthenosphere and deep mantle tidal dissipation models. However, persistent hot spots and active plumes are concentrated toward lower latitudes, and this distribution favors the asthenosphere rather than the deep mantle tidal dissipation model. ?? 1999 Academic Press.

Evaluation of dynamic infrared thermography as an alternative to CT angiography for perforator mapping in breast reconstruction: a clinical study.

PubMed

Weum, Sven; Mercer, James B; de Weerd, Louis

2016-07-15

The current gold standard for preoperative perforator mapping in breast reconstruction with a DIEP flap is CT angiography (CTA). Dynamic infrared thermography (DIRT) is an imaging method that does not require ionizing radiation or contrast injection. We evaluated if DIRT could be an alternative to CTA in perforator mapping. Twenty-five patients scheduled for secondary breast reconstruction with a DIEP flap were included. Preoperatively, the lower abdomen was examined with hand-held Doppler, DIRT and CTA. Arterial Doppler sound locations were marked on the skin. DIRT examination involved rewarming of the abdominal skin after a mild cold challenge. The locations of hot spots on DIRT were compared with the arterial Doppler sound locations. The rate and pattern of rewarming of the hot spots were analyzed. Multiplanar CT reconstructions were used to see if hot spots were related to perforators on CTA. All flaps were based on the perforator selected with DIRT and the surgical outcome was analyzed. First appearing hot spots were always associated with arterial Doppler sounds and clearly visible perforators on CTA. The hot spots on DIRT images were always slightly laterally located in relation to the exit points of the associated perforators through the rectus abdominis fascia on CTA. Some periumbilical perforators were not associated with hot spots and showed communication with the superficial inferior epigastric vein on CTA. The selected perforators adequately perfused all flaps. This study confirms that perforators selected with DIRT have arterial Doppler sound, are clearly visible on CTA and provide adequate perfusion for DIEP breast reconstruction. Retrospectively registered at ClinicalTrials.gov with identifier NCT02806518 .

Resolving hot spot microstructure using x-ray penumbral imaging (invited)

NASA Astrophysics Data System (ADS)

Bachmann, B.; Hilsabeck, T.; Field, J.; Masters, N.; Reed, C.; Pardini, T.; Rygg, J. R.; Alexander, N.; Benedetti, L. R.; Döppner, T.; Forsman, A.; Izumi, N.; LePape, S.; Ma, T.; MacPhee, A. G.; Nagel, S.; Patel, P.; Spears, B.; Landen, O. L.

2016-11-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Hot-Spot Ignition Mechanisms for Explosives and Propellants

NASA Astrophysics Data System (ADS)

Field, J. E.; Bourne, N. K.; Palmer, S. J. P.; Walley, S. M.

1992-05-01

This paper describes the response of explosives to stress and impact and in particular the mechanisms of `hot-spot' production. Samples in the form of single crystals, powder layers, pressed pellets, gels, polymer bonded explosives (PBXs) and propellants have been studied. Techniques used include a drop-weight facility with transparent anvils which allows photography at microsecond framing intervals, an instrumented drop-weight machine, a miniaturized Hopkinson bar system for high strain rate property measurement, laser speckle for studying the deformation and fracture of PBXs, an automated system for analysing speckle patterns and heat sensitive film for recording the positions and temperatures of hot spots. Polishing and staining methods have been developed to observe the microstructure of PBXs and failure during quasi-static loading. Ignition, when it occurred, took place at local hot-spot sites. Evidence is discussed for a variety of ignition mechanisms including adiabatic shear of the explosive, adiabatic heating of trapped gases during cavity collapse, viscous flow, friction, fracture and shear of added particles and triboluminescent discharge.

Mobile Launch Platform Vehicle Assembly Building Area (SWMU 056) Hot Spot 3 Bioremediation Interim Measures Work Plan, Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Whitney L. Morrison; Daprato, Rebecca C.

2016-01-01

This Interim Measures Work Plan (IMWP) presents an approach and design for the remediation of chlorinated volatile organic compound (CVOC) groundwater impacts using bioremediation (biostimulation and bioaugmentation) in Hot Spot 3, which is defined by the area where CVOC (trichloroethene [TCE], cis-1,2-dichloroethene [cDCE], and vinyl chloride [VC]) concentrations are greater than 10 times their respective Florida Department of Environmental Protection (FDEP) Natural Attenuation Default Concentration (NADC) [10xNADC] near the western Mobile Launch Platform (MLP) structure. The IM treatment area is the Hot Spot 3 area, which is approximately 0.07 acres and extends from approximately 6 to 22 and 41 to 55 feet below land surface (ft BLS). Within Hot Spot 3, a source zone (SZ; area with TCE concentrations greater than 1% solubility [11,000 micrograms per liter (micrograms/L)]) was delineated and is approximately 0.02 acres and extends from approximately 6 to 16 and 41 to 50 ft BLS.

Transcriptional specificity in various p53-mutant cells.

PubMed

Okaichi, Kumio; Izumi, Nanaka; Takamura, Yuma; Fukui, Shoichi; Kudo, Takashi

2013-03-01

Mutation of the tumor suppressor gene p53 is the most common genetic alteration observed in human tumors. However, the relationship between the mutation point of p53 and the transcriptional specificity is not so obvious. We prepared Saos-2 cells with various mutations of p53 that are found in human tumors, and examined the resulting transcriptional alterations in the cells. Loss of function and gain of function were observed in all p53 mutants. Hot-spot mutations of p53 are frequently found in tumor cells. We compared hot-spot mutations and other mutations of p53 and found that a more than 2-fold transcription of CADPS2, PIWIL4 and TRIM9 was induced by hot spot mutations, but not by other mutations. As PIWIL4 suppresses the p16(INK4A) and ARF pathway, restraining cell growth and genomic instability, induction of PIWIL4 expression may be one reason why hot-spot mutations are frequently found in tumor cells.

[Rapid detection of hot spot mutations of FGFR3 gene with PCR-high resolution melting assay].

PubMed

Li, Shan; Wang, Han; Su, Hua; Gao, Jinsong; Zhao, Xiuli

2017-08-10

To identify the causative mutations in five individuals affected with dyschondroplasia and develop an efficient procedure for detecting hot spot mutations of the FGFR3 gene. Genomic DNA was extracted from peripheral blood samples with a standard phenol/chloroform method. PCR-Sanger sequencing was used to analyze the causative mutations in the five probands. PCR-high resolution melting (HRM) was developed to detect the identified mutations. A c.1138G>A mutation in exon 8 was found in 4 probands, while a c.1620C>G mutation was found in exon 11 of proband 5 whom had a mild phenotype. All patients were successfully distinguished from healthy controls with the PCR-HRM method. The results of HRM analysis were highly consistent with that of Sanger sequencing. The Gly380Arg and Asn540Lys are hot spot mutations of the FGFR3 gene among patients with ACH/HCH. PCR-HRM analysis is more efficient for detecting hot spot mutations of the FGFR3 gene.

Heat flow from Io /JI/

NASA Technical Reports Server (NTRS)

Matson, D. L.; Ransford, G. A.; Johnson, T. V.

1981-01-01

The existing ground-based measurements of Io's thermal emission at infrared wavelengths of 8.4, 10.6, and 21 microns have been reexamined. Present in these data is the signature of hot spots, presumably similar to the hot spots seen by the IRIS experiment on Voyager. It is possible to extract from these data the total amount of power radiated. Since the hot spots are believed to be a result of deep-seated activity in Io and since the remainder of Io's surface is an extraordinarily poor thermal conductor, the power radiated by the hot spots is essentially the total heat flow. The analysis yields a heat flow of 2 + or - 1 W/sq m. This value is tremendously large in comparison to the average heat flow of the earth (0.06 W/sq m) and the moon (0.02 W/sq m), but is characteristic of active geothermal areas on the earth. A heat flow this large requires that the interior of Io be at least partially molten on a global scale.

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

PubMed

Regan, S P; Goncharov, V N; Igumenshchev, I V; Sangster, T C; Betti, R; Bose, A; Boehly, T R; Bonino, M J; Campbell, E M; Cao, D; Collins, T J B; Craxton, R S; Davis, A K; Delettrez, J A; Edgell, D H; Epstein, R; Forrest, C J; Frenje, J A; Froula, D H; Gatu Johnson, M; Glebov, V Yu; Harding, D R; Hohenberger, M; Hu, S X; Jacobs-Perkins, D; Janezic, R; Karasik, M; Keck, R L; Kelly, J H; Kessler, T J; Knauer, J P; Kosc, T Z; Loucks, S J; Marozas, J A; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Myatt, J F; Obenschain, S P; Petrasso, R D; Radha, P B; Rice, B; Rosenberg, M J; Schmitt, A J; Schmitt, M J; Seka, W; Shmayda, W T; Shoup, M J; Shvydky, A; Skupsky, S; Solodov, A A; Stoeckl, C; Theobald, W; Ulreich, J; Wittman, M D; Woo, K M; Yaakobi, B; Zuegel, J D

2016-07-08

A record fuel hot-spot pressure P_{hs}=56±7  Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, 011201(R) (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

Hot-spot selection and evaluation methods for whole slice images of meningiomas and oligodendrogliomas.

PubMed

Swiderska, Zaneta; Markiewicz, Tomasz; Grala, Bartlomiej; Slodkowska, Janina

2015-01-01

The paper presents a combined method for an automatic hot-spot areas selection based on penalty factor in the whole slide images to support the pathomorphological diagnostic procedure. The studied slides represent the meningiomas and oligodendrogliomas tumor on the basis of the Ki-67/MIB-1 immunohistochemical reaction. It allows determining the tumor proliferation index as well as gives an indication to the medical treatment and prognosis. The combined method based on mathematical morphology, thresholding, texture analysis and classification is proposed and verified. The presented algorithm includes building a specimen map, elimination of hemorrhages from them, two methods for detection of hot-spot fields with respect to an introduced penalty factor. Furthermore, we propose localization concordance measure to evaluation localization of hot spot selection by the algorithms in respect to the expert's results. Thus, the results of the influence of the penalty factor are presented and discussed. It was found that the best results are obtained for 0.2 value of them. They confirm effectiveness of applied approach.

Resolving hot spot microstructure using x-ray penumbral imaging (invited).

PubMed

Bachmann, B; Hilsabeck, T; Field, J; Masters, N; Reed, C; Pardini, T; Rygg, J R; Alexander, N; Benedetti, L R; Döppner, T; Forsman, A; Izumi, N; LePape, S; Ma, T; MacPhee, A G; Nagel, S; Patel, P; Spears, B; Landen, O L

2016-11-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Peering through Jupiter’s clouds with radio spectral imaging

NASA Astrophysics Data System (ADS)

de Pater, Imke; Sault, R. J.; Butler, Bryan; DeBoer, David; Wong, Michael H.

2016-06-01

Radio wavelengths can probe altitudes in Jupiter’s atmosphere below its visible cloud layers. We used the Very Large Array to map this unexplored region down to ~8 bar, ~100 kilometers below the visible clouds. Our maps reveal a dynamically active planet at pressures less than 2 to 3 bar. A radio-hot belt exists, consisting of relatively transparent regions (a low ammonia concentration, NH3 being the dominant source of opacity) probing depths to over ~8 bar; these regions probably coincide with 5-micrometer hot spots. Just to the south we distinguish an equatorial wave, bringing up ammonia gas from Jupiter’s deep atmosphere. This wave has been theorized to produce the 5-micrometer hot spots; we observed the predicted radio counterpart of such hot spots.

Infrared sensor for hot spot recognition for a small satellite mission

NASA Astrophysics Data System (ADS)

Skrbek, W.; Bachmann, K.; Lorenz, E.; Neidhardt, M.; Peschel, M.; Walter, I.; Zender, B.

1996-11-01

High temperature events strongly influence the environmental processes. Therefore, their observation is an important constituent of the global monitoring network. Unfortunately the current remote sensing systems are not able to deliver the necessary information about the world wide burn out of vegetation and its consequences. For global observations a dedicated system of small satellites is required. The main components of the corresponding instrumentation are the infrared channels. The proposed HSRS (HOT SPOT RECOGNITION SENSOR) has to demonstrate the possibilities of an such instrumentation and its feasibility for small satellites. The main drawbacks of the HSRS design are the handling of the hot spot recognition in the subpixel area and of the saturation in the case of larger hot areas by a suitable signal processing hardware.

Catalogue of UBVRI photometry of T Tauri stars and analysis of the causes of their variability

NASA Astrophysics Data System (ADS)

Herbst, W.; Herbst, D. K.; Grossman, E. J.; Weinstein, D.

1994-11-01

A computer-based catalogue of UBVRI photoelectric photometry of T Tauri stars and their earlier type analogs has been compiled. It presently includes over 10 000 entries on 80 stars and will be updated on a regular basis; it is available on Internet. The catalogue is used to analyze the sometimes bizarre light variations of pre-main-sequence stars on time scales of days to months in an attempt to illuminate the nature and causes of the phenomenon. It is useful in discussing their light variations to divide the stars into three groups according to their spectra. These are: weak T Tauri stars (WTTS; spectral class later than K0 and WH-alpha less than 10 A, classical T Tauri stars (CTTS; spectral class later than K0 and WH-alpha greater than 10 A), and early type T Tauri stars (ETTS; spectral class of K0 or earlier). Three distinct types of variability are displayed by stars in the catalogue. Type I variations are periodic in VRI and undoubtedly caused by rotational modulation of a star with an asymmetric distribution of cool spots on its surface. Irregular flare activity is sometimes seen on such stars in U and B. Type I variations are easiest to see on WTTS but are clearly present on CTTS and ETTS as well. Type II variations are caused by hot 'spots' or zones and, it is argued, result from changes in the excess or 'veiling' continuum commonly attributed to an accretion boundary layer or impact zone of a magnetically channeled accretion flow. This type of variation is seen predominantly or solely in CTTS. A sub-category, designated Type IIp, consists of stars which display periodic variations caused by hot spots. Whereas cool spots may last for hundreds or thousands of rotations, hot spots appear to come and go on a much shorter time scale. This suggests that both unsteady accretion and rotation of the star contribute to Type II variations. It is shown that a third type of variation exists among ETTS, including stars as early as A type. UX Ori is a typical example and we call these Type III variables or UXors. Their distinguishing characteristic is that they can display very large amplitudes (exceeding 2.8 mag in V) while showing little or no evidence for a veiling continuum or any substantial change in their photospheric spectra. If Type III variations are caused by changes in accretion luminosity, then boundary layers or impact zones in ETTS must be much different from CTTS which, of course, is possible since mass accretion rates are probably much higher. However, the leading hypothesis for explaining Type III variations is variable obscuration by circumstellar dust.

Automated analysis of hot spot X-ray images at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Khan, S. F.; Izumi, N.; Glenn, S.; Tommasini, R.; Benedetti, L. R.; Ma, T.; Pak, A.; Kyrala, G. A.; Springer, P.; Bradley, D. K.; Town, R. P. J.

2016-11-01

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ˜4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Jupiter's atmospheric composition from the Cassini thermal infrared spectroscopy experiment

NASA Technical Reports Server (NTRS)

Kunde, V. G.; Flasar, F. M.; Jennings, D. E.; Bezard, B.; Strobel, D. F.; Conrath, B. J.; Nixon, C. A.; Bjoraker, G. L.; Romani, P. N.; Achterberg, R. K.;

Automated analysis of hot spot X-ray images at the National Ignition Facility

DOE PAGES

Khan, S. F.; Izumi, N.; Glenn, S.; ...

2016-09-02

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. Here, for implosions with temperatures above ~4keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Powerful Radio Galaxies with Simbol-X: Lobes and Hot Spots

NASA Astrophysics Data System (ADS)

Migliori, G.; Grandi, P.; Angelini, L.; Raimondi, L.; Torresi, E.; Palumbo, G. G. C.

2009-05-01

We present here the first Simbol-X simulations of the extended components, lobes and hot spots, of the radio galaxies. We use the paradigmatic case of Pictor A to test the capabilities of Simbol-X in this field of studies. Simulations demonstrate that Simbol-X will be able not only to perform spatially resolved studies on the lobes of radio galaxies below 10 keV but also to observe, for the first time, hard X-ray emission from the hot spots. These extremely promising results show the considerable potentiality of Simbol-X in studying interaction phenomena between relativistic plasma and surrounding environment.

Automated analysis of hot spot X-ray images at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, S. F., E-mail: khan9@llnl.gov; Izumi, N.; Glenn, S.

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Automated analysis of hot spot X-ray images at the National Ignition Facility.

PubMed

Khan, S F; Izumi, N; Glenn, S; Tommasini, R; Benedetti, L R; Ma, T; Pak, A; Kyrala, G A; Springer, P; Bradley, D K; Town, R P J

2016-11-01

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Optical, IUE, and ROSAT observations of the eclipsing nova-like variable V347 Puppis (LB 1800)

NASA Technical Reports Server (NTRS)

Mauche, Christopher W.; Raymond, John C.; Buckley, David A. H.; Mouchet, Martine; Bonnell, Jerry; Sullivan, Denis J.; Bonnet-Bidaud, Jean-Marc; Bunk, Wolfram H.

1994-01-01

Using time-resolved optical spectroscopy and UBVRI and high-speed photometry obtained at Mount Stromlo Observatory, Mount John University Observatory, and the South African Astronomical Observatory; International Ultraviolet Explorer (IUE) ultraviolet spectroscopy; and Roentgen Satellite (ROSAT) survey X-ray fluxes, we present a study of the accretion disk, hot spot, and emission line regions in the bright eclipsing nova-like variable V347 Pup (LB 1800). In the optical and UV, V347 Pup is a strong emission line source with a continuum spectrum which is remarkably red for a high-M cataclysmic variable. Consistent with its high inclination, we interpret the continuum spectrum as the superposition of the spectrum of the cool (T(sub eff) approximately 7000 K) outer edge and the hot (T(sub eff) approximately 100,000 K) inner regions of a self-eclipsed accretion disk. For the assumed parameters, the model matches the level and shape of the observed spectrum for an inclination of approximately 88 and a distance of approximately 300 pc. The prominent hump in the optical and UV light curves just before eclipse manifests the presence of the hot spot where the accretion stream strikes the edge of the disk. The wavelength dependence of the amplitude of the hump is best modeled by a spot having an effective temperature of approximately 25,000 K and an area of approximately 3 x 10(exp 18) sq cm if the spot radiates like a blackbody, or an effective temperatue of approximately 14,000 K and an area of approximately 3 x 10(exp 19) sq cm if it radiates with a stellar spectrum. In either case, the hot spot produces only one-tenth of the predicted luminosity for the assumed mass-transfer rate of 10(exp -8) solar mass/yr. Either the hot spot is 'buried' in the edge of the accretion disk, or a significant fraction of its luminosity is radiated away in lines. The difference in azimuth between the peak of the hump and the dynamically expected location of the hot spot suggests that the spot's emitting surface is rotated forward by approximately 36 deg relative to the edge of the disk.

Optical, IUE, and ROSAT observations of the eclipsing nova-like variable V347 Puppis (LB 1800)

NASA Astrophysics Data System (ADS)

Mauche, Christopher W.; Raymond, John C.; Buckley, David A. H.; Mouchet, Martine; Bonnell, Jerry; Sullivan, Denis J.; Bonnet-Bidaud, Jean-Marc; Bunk, Wolfram H.

1994-03-01

Using time-resolved optical spectroscopy and UBVRI and high-speed photometry obtained at Mount Stromlo Observatory, Mount John University Observatory, and the South African Astronomical Observatory; International Ultraviolet Explorer (IUE) ultraviolet spectroscopy; and Roentgen Satellite (ROSAT) survey X-ray fluxes, we present a study of the accretion disk, hot spot, and emission line regions in the bright eclipsing nova-like variable V347 Pup (LB 1800). In the optical and UV, V347 Pup is a strong emission line source with a continuum spectrum which is remarkably red for a high-M cataclysmic variable. Consistent with its high inclination, we interpret the continuum spectrum as the superposition of the spectrum of the cool (Teff approximately 7000 K) outer edge and the hot (Teff approximately 100,000 K) inner regions of a self-eclipsed accretion disk. For the assumed parameters, the model matches the level and shape of the observed spectrum for an inclination of approximately 88 and a distance of approximately 300 pc. The prominent hump in the optical and UV light curves just before eclipse manifests the presence of the hot spot where the accretion stream strikes the edge of the disk. The wavelength dependence of the amplitude of the hump is best modeled by a spot having an effective temperature of approximately 25,000 K and an area of approximately 3 x 1018 sq cm if the spot radiates like a blackbody, or an effective temperatue of approximately 14,000 K and an area of approximately 3 x 1019 sq cm if it radiates with a stellar spectrum. In either case, the hot spot produces only one-tenth of the predicted luminosity for the assumed mass-transfer rate of 10-8 solar mass/yr. Either the hot spot is 'buried' in the edge of the accretion disk, or a significant fraction of its luminosity is radiated away in lines. The difference in azimuth between the peak of the hump and the dynamically expected location of the hot spot suggests that the spot's emitting surface is rotated forward by approximately 36 deg relative to the edge of the disk.

Monitoring the South Atlantic Anomaly Using ATSR

NASA Astrophysics Data System (ADS)

Casadio, Stefano; Arino, Olivier; Serpe, Danilo

2010-12-01

Space mission planning needs to quantify the risks arising from exposure to high doses of radiation, as to both the effects on human health and the impact on instrumental efficiency. Constant monitoring of the South Atlantic Anomaly (SAA) is therefore required as it is a major cause of radiation flux increase. In order to address this need, the time evolution of the particle induced noise of the SWIR channels of the Along Track Scanning Radiometer (ATSR) instrument series is analysed in the 1991-2009 time window. The data considered in this work are the night-time SWIR hot spots generated by energetic particles hitting the ATSR detectors when satellites pass through the SAA region. To avoid misinterpretation of results, hot spots due to wildfires (individuated from the ATSR World Fire Atlas products) have been removed. The location and area of the SAA are inferred by fitting a two-dimensional, elliptical Gaussian equation to the SWIR (1.6 μm) night- time hot spots detected over the SAA region. The location of the SAA is found to drift westwards with an average drift rate of about 0.35 deg/yr and northward with an average drift rate of about 0.12 deg/yr. These results are in very good agreement with latest works. Irregularities are found where the speed of the drift changes and the SAA moves eastward and southward, especially in the late 1991 and 2002-2003 time windows. These drift anomalies are attributed to geomagnetic jerks. Results indicate that, as expected, the strength and the area of the SAA are anti-correlated with the sun-spot numbers (SSN) and the 11.7 cm Solar Flux (SF).

The evolution of the temperature field during cavity collapse in liquid nitromethane. Part II: reactive case

NASA Astrophysics Data System (ADS)

Michael, L.; Nikiforakis, N.

2018-02-01

This work is concerned with the effect of cavity collapse in non-ideal explosives as a means of controlling their sensitivity. The main objective is to understand the origin of localised temperature peaks (hot spots) which play a leading order role at the early stages of ignition. To this end, we perform two- and three-dimensional numerical simulations of shock-induced single gas-cavity collapse in liquid nitromethane. Ignition is the result of a complex interplay between fluid dynamics and exothermic chemical reaction. In the first part of this work, we focused on the hydrodynamic effects in the collapse process by switching off the reaction terms in the mathematical formulation. In this part, we reinstate the reactive terms and study the collapse of the cavity in the presence of chemical reactions. By using a multi-phase formulation which overcomes current challenges of cavity collapse modelling in reactive media, we account for the large density difference across the material interface without generating spurious temperature peaks, thus allowing the use of a temperature-based reaction rate law. The mathematical and physical models are validated against experimental and analytic data. In Part I, we demonstrated that, compared to experiments, the generated hot spots have a more complex topological structure and that additional hot spots arise in regions away from the cavity centreline. Here, we extend this by identifying which of the previously determined high-temperature regions in fact lead to ignition and comment on the reactive strength and reaction growth rate in the distinct hot spots. We demonstrate and quantify the sensitisation of nitromethane by the collapse of the isolated cavity by comparing the ignition times of nitromethane due to cavity collapse and the ignition time of the neat material. The ignition in both the centreline hot spots and the hot spots generated by Mach stems occurs in less than half the ignition time of the neat material. We compare two- and three-dimensional simulations to examine the change in topology, temperatures, and reactive strength of the hot spots by the third dimension. It is apparent that belated ignition times can be avoided by the use of three-dimensional simulations. The effect of the chemical reactions on the topology and strength of the hot spots in the timescales considered is also studied, in a comparison between inert and reactive simulations where maximum temperature fields and their growth rates are examined.

Encoding Random Hot Spots of a Volume Gold Nanorod Assembly for Ultralow Energy Memory.

PubMed

Dai, Qiaofeng; Ouyang, Min; Yuan, Weiguang; Li, Jinxiang; Guo, Banghong; Lan, Sheng; Liu, Songhao; Zhang, Qiming; Lu, Guang; Tie, Shaolong; Deng, Haidong; Xu, Yi; Gu, Min

2017-09-01

Data storage with ultrahigh density, ultralow energy, high security, and long lifetime is highly desirable in the 21st century and optical data storage is considered as the most promising way to meet the challenge of storing big data. Plasmonic coupling in regularly arranged metallic nanoparticles has demonstrated its superior properties in various applications due to the generation of hot spots. Here, the discovery of the polarization and spectrum sensitivity of random hot spots generated in a volume gold nanorod assembly is reported. It is demonstrated that the two-photon-induced absorption and two-photon-induced luminescence of the gold nanorods adjacent to such hot spots are enhanced significantly because of plasmonic coupling. The polarization, wavelength, and spatial multiplexing of the hot spots can be realized by using an ultralow energy of only a few picojoule per pulse, which is two orders of magnitude lower than the value in the state-of-the-art technology that utilizes isolated gold nanorods. The ultralow recording energy reduces the cross-talk between different recording channels and makes it possible to realize rewriting function, improving significantly both the quality and capacity of optical data storage. It is anticipated that the demonstrated technology can facilitate the development of multidimensional optical data storage for a greener future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HotSpot Wizard 3.0: web server for automated design of mutations and smart libraries based on sequence input information.

PubMed

Sumbalova, Lenka; Stourac, Jan; Martinek, Tomas; Bednar, David; Damborsky, Jiri

2018-05-23

HotSpot Wizard is a web server used for the automated identification of hotspots in semi-rational protein design to give improved protein stability, catalytic activity, substrate specificity and enantioselectivity. Since there are three orders of magnitude fewer protein structures than sequences in bioinformatic databases, the major limitation to the usability of previous versions was the requirement for the protein structure to be a compulsory input for the calculation. HotSpot Wizard 3.0 now accepts the protein sequence as input data. The protein structure for the query sequence is obtained either from eight repositories of homology models or is modeled using Modeller and I-Tasser. The quality of the models is then evaluated using three quality assessment tools-WHAT_CHECK, PROCHECK and MolProbity. During follow-up analyses, the system automatically warns the users whenever they attempt to redesign poorly predicted parts of their homology models. The second main limitation of HotSpot Wizard's predictions is that it identifies suitable positions for mutagenesis, but does not provide any reliable advice on particular substitutions. A new module for the estimation of thermodynamic stabilities using the Rosetta and FoldX suites has been introduced which prevents destabilizing mutations among pre-selected variants entering experimental testing. HotSpot Wizard is freely available at http://loschmidt.chemi.muni.cz/hotspotwizard.

Silver Nanoparticle-Decorated Shape-Memory Polystyrene Sheets as Highly Sensitive Surface-Enhanced Raman Scattering Substrates with a Thermally Inducible Hot Spot Effect.

PubMed

Mengesha, Zebasil Tassew; Yang, Jyisy

2016-11-15

In this study, an active surface-enhanced Raman scattering (SERS) substrate with a thermally inducible hot spot effect for sensitive measurement of Raman-active molecules was successfully fabricated from silver nanoparticle (AgNP)-decorated shape-memory polystyrene (SMP) sheets. To prepare the SERS substrate, SMP sheets were first pretreated with n-octylamine for effective decoration with AgNPs. By varying the formulation and condition of the reduction reaction, AgNP-decorated SMP (Ag@SMP) substrates were successfully prepared with optimized particle gaps to produce inducible hot spot effects on thermal shrink. High-quality SERS spectra were easily obtained with enhancement factors higher than 10 8 by probing with aromatic thiols. Several Ag@SMP substrates produced under different reaction conditions were explored for the creation of inducible hot spot effects. The results indicated that AgNP spacing is crucial for strong hot spot effects. The suitability of Ag@SMP substrates for quantification was also evaluated according to the detection of adenine. Results confirmed that prepared Ag@SMP substrates were highly suitable for quantitative analysis because they yielded an estimated limit of detection as low as 120 pg/cm 2 , a linear range of up to 7 ng/cm 2 , and a regression coefficient (R 2 ) of 0.9959. Ag@SMP substrates were highly reproducible; the average relative standard deviation for all measurements was less than 10%.

Phenomenological model for the evolution of radio galaxies such as Cygnus A

NASA Astrophysics Data System (ADS)

Artyukh, V. S.

2015-06-01

A phenomenological model for the evolution of classical radio galaxies such as Cygnus A is presented. An activity cycle of the host galaxy in the radio begins with the birth of radio jets, which correspond to shocks on scales ˜1 pc (the radio galaxy B0108+388). In the following stage of the evolution, the radio emission comes predominantly from formations on scales of 10-100 pc, whose physical parameters are close to those of the hot spots of Cygnus A (this corresponds to GHz-peaked spectrum radio sources). Further, the hot spots create radio lobes on scales of 103-104 pc (compact steep-spectrum radio sources). The fully formed radio galaxies have radio jets, hot spots, and giant radio lobes; the direction of the jets can vary in a discrete steps with time, creating new hot spots and inflating the radio lobes (as in Cygnus A). In the final stage of the evolutionary cycle, first the radio jets disappear, then the hot spots, and finally the radio lobes (similar to the giant radio galaxies DA 240 and 3C 236). A large fraction of radio galaxies with repeating activity cycles is observed. The close connection between Cygnus A-type radio galaxies and optical quasars is noted, as well as similarity in the cosmological evolution of powerful radio galaxies and optical quasars.

Spectral Eclipse Timing

NASA Astrophysics Data System (ADS)

Dobbs-Dixon, Ian; Agol, Eric; Deming, Drake

2015-12-01

We utilize multi-dimensional simulations of varying equatorial jet strength to predict wavelength-dependent variations in the eclipse times of gas-giant planets. A displaced hot spot introduces an asymmetry in the secondary eclipse light curve that manifests itself as a measured offset in the timing of the center of eclipse. A multi-wavelength observation of secondary eclipse, one probing the timing of barycentric eclipse at short wavelengths and another probing at longer wavelengths, will reveal the longitudinal displacement of the hot spot and break the degeneracy between this effect and that associated with the asymmetry due to an eccentric orbit. The effect of time offsets was first explored in the IRAC wavebands by Williams et al. Here we improve upon their methodology, extend to a broad range of wavelengths, and demonstrate our technique on a series of multi-dimensional radiative-hydrodynamical simulations of HD 209458b with varying equatorial jet strength and hot-spot displacement. Simulations with the largest hot-spot displacement result in timing offsets of up to 100 s in the infrared. Though we utilize a particular radiative hydrodynamical model to demonstrate this effect, the technique is model independent. This technique should allow a much larger survey of hot-spot displacements with the James Webb Space Telescope than currently accessible with time-intensive phase curves, hopefully shedding light on the physical mechanisms associated with thermal energy advection in irradiated gas giants.

The independent pulsations of Jupiter's northern and southern X-ray auroras

NASA Astrophysics Data System (ADS)

Dunn, W. R.; Branduardi-Raymont, G.; Ray, L. C.; Jackman, C. M.; Kraft, R. P.; Elsner, R. F.; Rae, I. J.; Yao, Z.; Vogt, M. F.; Jones, G. H.; Gladstone, G. R.; Orton, G. S.; Sinclair, J. A.; Ford, P. G.; Graham, G. A.; Caro-Carretero, R.; Coates, A. J.

2017-11-01

Auroral hot spots are observed across the Universe at different scales1 and mark the coupling between a surrounding plasma environment and an atmosphere. Within our own Solar System, Jupiter possesses the only resolvable example of this large-scale energy transfer. Jupiter's northern X-ray aurora is concentrated into a hot spot, which is located at the most poleward regions of the planet's aurora and pulses either periodically2,3 or irregularly4,5. X-ray emission line spectra demonstrate that Jupiter's northern hot spot is produced by high charge-state oxygen, sulfur and/or carbon ions with an energy of tens of MeV (refs 4-6) that are undergoing charge exchange. Observations instead failed to reveal a similar feature in the south2,3,7,8. Here, we report the existence of a persistent southern X-ray hot spot. Surprisingly, this large-scale southern auroral structure behaves independently of its northern counterpart. Using XMM-Newton and Chandra X-ray campaigns, performed in May-June 2016 and March 2007, we show that Jupiter's northern and southern spots each exhibit different characteristics, such as different periodic pulsations and uncorrelated changes in brightness. These observations imply that highly energetic, non-conjugate magnetospheric processes sometimes drive the polar regions of Jupiter's dayside magnetosphere. This is in contrast to current models of X-ray generation for Jupiter9,10. Understanding the behaviour and drivers of Jupiter's pair of hot spots is critical to the use of X-rays as diagnostics of the wide range of rapidly rotating celestial bodies that exhibit these auroral phenomena.

Evolution and Persistence of 5-um Hot Spots at the Galileo Probe entry Latitude

NASA Technical Reports Server (NTRS)

Fisher, B. M.

1997-01-01

We present a study on the longtudinal locations, morphology and evolution of the 5-um hot spots at 6.5 deg. N latitude (planetocentric), from an extensive IRTF-NSFCAM data set spanning more that 3 years, which includes the date of the Galileo Probe entry.

Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

DOE PAGES

Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

2016-08-01

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed bymore » coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.« less

Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed bymore » coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.« less

The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, A.; Betti, R.; Shvarts, D.

To achieve ignition with inertial confinement fusion (ICF), it is important to under- stand the effect of asymmetries on the hydrodynamics and energetics of the compres- sion. This paper describes a theoretical model for the compression of distorted hot spots, and quantitative estimates using hydrodynamic simulations. The asymmetries are categorized into low (Ι < 6) and intermediate (Ι < A < 40) modes by comparison of the wavelength with the thermal-diffusion scale length. Long-wavelength modes introduce substantial nonradial motion, whereas intermediate-wavelength modes in- volve more cooling by thermal ablation. We discover that for distorted hot spots, the measured neutron-averaged propertiesmore » can be very different from the real hydro- dynamic conditions. This is because mass ablation driven my thermal conduction introduces flows in the Rayleigh–Taylor bubbles, this results in pressure variation, in addition to temperature variation between the bubbles and the neutron-producing region (~1 keV for intermediate modes). The differences are less pronounced for long-wavelength asymmetries since the bubbles are relatively hot and sustain fusion reactions. The yield degradation$-$ with respect to the symmetric$-$ results primarily from a reduction in the hot-spot pressure for low modes and from a reduction in burn volume for intermediate modes. It is shown that the degradation in internal energy of the hot-spot is equivalent for both categories, and is equal to the total residual energy in the shell including the bubbles. This quantity is correlated with the shell residual kinetic energy for low-modes, and includes the kinetic energy in the bubbles for mid-modes.« less

The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics

DOE PAGES

Bose, A.; Betti, R.; Shvarts, D.; ...

2017-10-03

To achieve ignition with inertial confinement fusion (ICF), it is important to under- stand the effect of asymmetries on the hydrodynamics and energetics of the compres- sion. This paper describes a theoretical model for the compression of distorted hot spots, and quantitative estimates using hydrodynamic simulations. The asymmetries are categorized into low (Ι < 6) and intermediate (Ι < A < 40) modes by comparison of the wavelength with the thermal-diffusion scale length. Long-wavelength modes introduce substantial nonradial motion, whereas intermediate-wavelength modes in- volve more cooling by thermal ablation. We discover that for distorted hot spots, the measured neutron-averaged propertiesmore » can be very different from the real hydro- dynamic conditions. This is because mass ablation driven my thermal conduction introduces flows in the Rayleigh–Taylor bubbles, this results in pressure variation, in addition to temperature variation between the bubbles and the neutron-producing region (~1 keV for intermediate modes). The differences are less pronounced for long-wavelength asymmetries since the bubbles are relatively hot and sustain fusion reactions. The yield degradation$-$ with respect to the symmetric$-$ results primarily from a reduction in the hot-spot pressure for low modes and from a reduction in burn volume for intermediate modes. It is shown that the degradation in internal energy of the hot-spot is equivalent for both categories, and is equal to the total residual energy in the shell including the bubbles. This quantity is correlated with the shell residual kinetic energy for low-modes, and includes the kinetic energy in the bubbles for mid-modes.« less

A hot-spot-active magnetic graphene oxide substrate for microRNA detection based on cascaded chemiluminescence resonance energy transfer.

PubMed

Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying

2015-02-28

Herein, a cascaded chemiluminescence resonance energy transfer (C-CRET) process was demonstrated from horseradish peroxidase (HRP)-mimicking DNAzyme-catalyzed luminol-H2O2 to fluorescein and further to graphene oxide (GO) when HRP-mimicking DNAzyme/fluorescein was in close proximity to the GO surface. The proposed C-CRET system was successfully implemented to construct three modes of C-CRET hot-spot-active substrates (modes I, II and III) by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs (hot-spot-generation probes) on magnetic GO (MGO), resulting in a signal "off" state due to the quenching of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122 (miRNA-122), the targets (mode I) or the new triggers that were generated through a strand displacement reaction (SDR) initiated by miRNA-122 (modes II and III) hybridized with the loop domains of hairpin probes on MGO to form double-stranded (modes I and II) or triplex-stem structures (mode III), causing an "open" configuration of the hairpin probe and a CRET signal "on" state, thus achieving sensitive and selective detection of miRNA-122. More importantly, the substrate exhibited excellent controllability, reversibility and reproducibility through SDR and magnetic separation (modes II and III), especially sequence-independence for hairpin probes in mode III, holding great potential for the development of a versatile platform for optical biosensing.

The Red Queen model of recombination hot-spot evolution: a theoretical investigation.

PubMed

Latrille, Thibault; Duret, Laurent; Lartillot, Nicolas

2017-12-19

In humans and many other species, recombination events cluster in narrow and short-lived hot spots distributed across the genome, whose location is determined by the Zn-finger protein PRDM9. To explain these fast evolutionary dynamics, an intra-genomic Red Queen model has been proposed, based on the interplay between two antagonistic forces: biased gene conversion, mediated by double-strand breaks, resulting in hot-spot extinction, followed by positive selection favouring new PRDM9 alleles recognizing new sequence motifs. Thus far, however, this Red Queen model has not been formalized as a quantitative population-genetic model, fully accounting for the intricate interplay between biased gene conversion, mutation, selection, demography and genetic diversity at the PRDM9 locus. Here, we explore the population genetics of the Red Queen model of recombination. A Wright-Fisher simulator was implemented, allowing exploration of the behaviour of the model (mean equilibrium recombination rate, diversity at the PRDM9 locus or turnover rate) as a function of the parameters (effective population size, mutation and erosion rates). In a second step, analytical results based on self-consistent mean-field approximations were derived, reproducing the scaling relations observed in the simulations. Empirical fit of the model to current data from the mouse suggests both a high mutation rate at PRDM9 and strong biased gene conversion on its targets.This article is part of the themed issue 'Evolutionary causes and consequences of recombination rate variation in sexual organisms'. © 2017 The Authors.

The Red Queen model of recombination hot-spot evolution: a theoretical investigation

PubMed Central

Latrille, Thibault; Duret, Laurent

2017-01-01

In humans and many other species, recombination events cluster in narrow and short-lived hot spots distributed across the genome, whose location is determined by the Zn-finger protein PRDM9. To explain these fast evolutionary dynamics, an intra-genomic Red Queen model has been proposed, based on the interplay between two antagonistic forces: biased gene conversion, mediated by double-strand breaks, resulting in hot-spot extinction, followed by positive selection favouring new PRDM9 alleles recognizing new sequence motifs. Thus far, however, this Red Queen model has not been formalized as a quantitative population-genetic model, fully accounting for the intricate interplay between biased gene conversion, mutation, selection, demography and genetic diversity at the PRDM9 locus. Here, we explore the population genetics of the Red Queen model of recombination. A Wright–Fisher simulator was implemented, allowing exploration of the behaviour of the model (mean equilibrium recombination rate, diversity at the PRDM9 locus or turnover rate) as a function of the parameters (effective population size, mutation and erosion rates). In a second step, analytical results based on self-consistent mean-field approximations were derived, reproducing the scaling relations observed in the simulations. Empirical fit of the model to current data from the mouse suggests both a high mutation rate at PRDM9 and strong biased gene conversion on its targets. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’. PMID:29109226

Reconstructing the History of Maize Streak Virus Strain A Dispersal To Reveal Diversification Hot Spots and Its Origin in Southern Africa ▿ †

PubMed Central

Monjane, Adérito L.; Harkins, Gordon W.; Martin, Darren P.; Lemey, Philippe; Lefeuvre, Pierre; Shepherd, Dionne N.; Oluwafemi, Sunday; Simuyandi, Michelo; Zinga, Innocent; Komba, Ephrem K.; Lakoutene, Didier P.; Mandakombo, Noella; Mboukoulida, Joseph; Semballa, Silla; Tagne, Appolinaire; Tiendrébéogo, Fidèle; Erdmann, Julia B.; van Antwerpen, Tania; Owor, Betty E.; Flett, Bradley; Ramusi, Moses; Windram, Oliver P.; Syed, Rizwan; Lett, Jean-Michel; Briddon, Rob W.; Markham, Peter G.; Rybicki, Edward P.; Varsani, Arvind

2011-01-01

Maize streak virus strain A (MSV-A), the causal agent of maize streak disease, is today one of the most serious biotic threats to African food security. Determining where MSV-A originated and how it spread transcontinentally could yield valuable insights into its historical emergence as a crop pathogen. Similarly, determining where the major extant MSV-A lineages arose could identify geographical hot spots of MSV evolution. Here, we use model-based phylogeographic analyses of 353 fully sequenced MSV-A isolates to reconstruct a plausible history of MSV-A movements over the past 150 years. We show that since the probable emergence of MSV-A in southern Africa around 1863, the virus spread transcontinentally at an average rate of 32.5 km/year (95% highest probability density interval, 15.6 to 51.6 km/year). Using distinctive patterns of nucleotide variation caused by 20 unique intra-MSV-A recombination events, we tentatively classified the MSV-A isolates into 24 easily discernible lineages. Despite many of these lineages displaying distinct geographical distributions, it is apparent that almost all have emerged within the past 4 decades from either southern or east-central Africa. Collectively, our results suggest that regular analysis of MSV-A genomes within these diversification hot spots could be used to monitor the emergence of future MSV-A lineages that could affect maize cultivation in Africa. PMID:21715477

Self-Generated Magnetic Fields in the Stagnation Phase of Indirect-Drive Implosions on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Walsh, C. A.; Chittenden, J. P.; McGlinchey, K.; Niasse, N. P. L.; Appelbe, B. D.

2017-04-01

Three-dimensional extended-magnetohydrodynamic simulations of the stagnation phase of inertial confinement fusion implosion experiments at the National Ignition Facility are presented, showing self-generated magnetic fields over 104 T . Angular high mode-number perturbations develop large magnetic fields, but are localized to the cold, dense hot-spot surface, which is hard to magnetize. When low-mode perturbations are also present, the magnetic fields are injected into the hot core, reaching significant magnetizations, with peak local thermal conductivity reductions greater than 90%. However, Righi-Leduc heat transport effectively cools the hot spot and lowers the neutron spectra-inferred ion temperatures compared to the unmagnetized case. The Nernst effect qualitatively changes the results by demagnetizing the hot-spot core, while increasing magnetizations at the edge and near regions of large heat loss.

Self-Generated Magnetic Fields in the Stagnation Phase of Indirect-Drive Implosions on the National Ignition Facility.

PubMed

Walsh, C A; Chittenden, J P; McGlinchey, K; Niasse, N P L; Appelbe, B D

2017-04-14

Three-dimensional extended-magnetohydrodynamic simulations of the stagnation phase of inertial confinement fusion implosion experiments at the National Ignition Facility are presented, showing self-generated magnetic fields over 10^{4}  T. Angular high mode-number perturbations develop large magnetic fields, but are localized to the cold, dense hot-spot surface, which is hard to magnetize. When low-mode perturbations are also present, the magnetic fields are injected into the hot core, reaching significant magnetizations, with peak local thermal conductivity reductions greater than 90%. However, Righi-Leduc heat transport effectively cools the hot spot and lowers the neutron spectra-inferred ion temperatures compared to the unmagnetized case. The Nernst effect qualitatively changes the results by demagnetizing the hot-spot core, while increasing magnetizations at the edge and near regions of large heat loss.

The Typical Number of Antiprotons Necessary to Heat the Hot Spot in the D-T Fuel Doped with U

NASA Astrophysics Data System (ADS)

Shmatov, M. L.

Fast ignition scenario with heating the hot spot by products of annihilation of antiprotons in the D-T fuel doped with U238 is considered. It is shown that in this scenario the hot spot is being heated effectively only by the fission fragments arising due to annihilation of the antiprotons on the nuclei of uranium. The presented model predicts that fast ignition can be provided by injection of (1.3 to 4.4) x 1015 antiprotons into the D-T fuel compressed to the density of about 200 g/cm3 and containing one nucleus of U238 per about one thousand nuclei of hydrogen isotopes.

76 FR 29235 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-20

.... Please note that EPA's policy is that public comments, whether submitted electronically or in paper, will... learning to perform quantitative hot-spot analyses; new burden associated with using the MOVES model for..., adjustment for increased burden associated with quantitative hot-spot analyses, an adjustment for the...

Environmental assessment hot spots of perforated forest in the eastern United States

Treesearch

Kurt H. Riitters; John W. Coulston

2005-01-01

National assessments of forest fragmentation satisfy international biodiversity conventions, but they do not identify specific places where ecological impacts are likely. In this article, we identify geographic concentrations (hot spots) of forest located near holes in otherwise intact forest canopies (perforated forest) in the eastern United States, and we describe...

PILOT-SCALE INCINERATION OF PCB-CONTAMINATED SEDIMENTS FROM THE NEW BEDFORD HARBOR HOT SPOT SUPERFUND SITE

EPA Science Inventory

Testing was performed at the EPA's Incineration Research Facility (IRF) to determine the incinerability of contaminated marine sediment from the Hot Spot in the New Bedford Harbor Superfund Site. he contaminants at this site were PCBs, at concentrations up to >200,000 mg/kg, and ...

Mapping the Hot Spots: A Zoning Approach to Space Analysis and Design

ERIC Educational Resources Information Center

Bunnell, Adam; Carpenter, Russell; Hensley, Emily; Strong, Kelsey; Williams, ReBecca; Winter, Rachel

2016-01-01

This article examines a preliminary approach to space design developed and implemented in Eastern Kentucky University's Noel Studio for Academic Creativity. The approach discussed here is entitled "hot spots," which has allowed the research team to observe trends in space usage and composing activities among students. This approach has…

Three-dimensional simulations of National Ignition Facility implosions: Insight into experimental observablesa)

NASA Astrophysics Data System (ADS)

Spears, Brian K.; Munro, David H.; Sepke, Scott; Caggiano, Joseph; Clark, Daniel; Hatarik, Robert; Kritcher, Andrea; Sayre, Daniel; Yeamans, Charles; Knauer, James; Hilsabeck, Terry; Kilkenny, Joe

2015-05-01

We simulate in 3D both the hydrodynamics and, simultaneously, the X-ray and neutron diagnostic signatures of National Ignition Facility (NIF) implosions. We apply asymmetric radiation drive to study the impact of low mode asymmetry on diagnostic observables. We examine X-ray and neutron images as well as neutron spectra for these perturbed implosions. The X-ray images show hot spot evolution on small length scales and short time scales, reflecting the incomplete stagnation seen in the simulation. The neutron images show surprising differences from the X-ray images. The neutron spectra provide additional measures of implosion asymmetry. Flow in the hot spot alters the neutron spectral peak, namely, the peak location and width. The changes in the width lead to a variation in the apparent temperature with viewing angle that signals underlying hot spot asymmetry. We compare our new expectations based on the simulated data with NIF data. We find that some recent cryogenic layered experiments show appreciable temperature anisotropy indicating residual flow in the hot spot. We also find some trends in the data that do not reflect our simulation and theoretical understanding.

Crack initiation and potential hot-spot formation around a cylindrical defect under dynamic compression

NASA Astrophysics Data System (ADS)

Ma, Xiao; Li, Xinguo; Zheng, Xianxu; Li, Kewu; Hu, Qiushi; Li, Jianling

2017-11-01

In recent decades, the hot-spot theory of condensed-phase explosives has been a compelling focus of scientific investigation attracting many researchers. The defect in the polymeric binder of the polymer-bonded explosive is called the intergranular defect. In this study, the real polymeric binder was substituted by poly(methyl methacrylate) (PMMA) as it is transparent and has similar thermodynamic properties to some binders. A set of modified split Hopkinson pressure bars equipped with a time-resolved shadowgraph was used to study the process of crack initiation and potential hot-spot formation around a cylindrical defect in PMMA. The new and significant phenomenon that the opening-mode crack emerged earlier than the shearing-mode crack from the cylindrical defect has been published for the first time in this paper. Furthermore, a two-dimensional numerical simulation was performed to show the evolution of both the stress field and the temperature field. The simulation results were in good agreement with the experiment. Finally, the law of potential hot-spot formation is discussed in detail.

Hot-spot heating susceptibility due to reverse bias operating conditions

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.

1985-01-01

Because of field experience (indicating that cell and module degradation could occur as a result of hot spot heating), a laboratory test was developed at JPL to determine hot spot susceptibility of modules. The initial hot spot testing work at JPL formed a foundation for the test development. Test parameters are selected as follows. For high shunt resistance cells, the applied back bias test current is set equal to the test cell current at maximum power. For low shunt resistance cells, the test current is set equal to the cell short circuit current. The shadow level is selected to conform to that which would lead to maximum back bias voltage under the appropriate test current level. The test voltage is determined by the bypass diode frequency. The test conditions are meant to simulate the thermal boundary conditions for 100 mW/sq cm, 40C ambient environment. The test lasts 100 hours. A key assumption made during the development of the test is that no current imbalance results from the connecting of multiparallel cell strings. Therefore, the test as originally developed was applicable for single string case only.

Deletion of exons 3-9 encompassing a mutational hot spot in the DMD gene presents an asymptomatic phenotype, indicating a target region for multiexon skipping therapy.

PubMed

Nakamura, Akinori; Fueki, Noboru; Shiba, Naoko; Motoki, Hirohiko; Miyazaki, Daigo; Nishizawa, Hitomi; Echigoya, Yusuke; Yokota, Toshifumi; Aoki, Yoshitsugu; Takeda, Shin'ichi

2016-07-01

Few cases of dystrophinopathy show an asymptomatic phenotype with mutations in the 5' (exons 3-7) hot spot in the Duchenne muscular dystrophy (DMD) gene. Our patient showed increased serum creatine kinase levels at 12 years of age. A muscle biopsy at 15 years of age led to a diagnosis of Becker muscular dystrophy. The patient showed a slight decrease in cardiac function at the age of 21 years and was administered a β-blocker, but there was no muscle involvement even at the age of 27 years. A deletion of exons 3-9 encompassing a mutational hot spot in the DMD gene was detected, and dystrophin protein expression was ∼15% that of control level. We propose that in-frame deletion of exons 3-9 may produce a functional protein, and that multiexon skipping therapy targeting these exons may be feasible for severe dystrophic patients with a mutation in the 5' hot spot of the DMD gene.

Solvent-accessible surface area: How well can be applied to hot-spot detection?

PubMed

Martins, João M; Ramos, Rui M; Pimenta, António C; Moreira, Irina S

2014-03-01

A detailed comprehension of protein-based interfaces is essential for the rational drug development. One of the key features of these interfaces is their solvent accessible surface area profile. With that in mind, we tested a group of 12 SASA-based features for their ability to correlate and differentiate hot- and null-spots. These were tested in three different data sets, explicit water MD, implicit water MD, and static PDB structure. We found no discernible improvement with the use of more comprehensive data sets obtained from molecular dynamics. The features tested were shown to be capable of discerning between hot- and null-spots, while presenting low correlations. Residue standardization such as rel SASAi or rel/res SASAi , improved the features as a tool to predict ΔΔGbinding values. A new method using support machine learning algorithms was developed: SBHD (Sasa-Based Hot-spot Detection). This method presents a precision, recall, and F1 score of 0.72, 0.81, and 0.76 for the training set and 0.91, 0.73, and 0.81 for an independent test set. Copyright © 2013 Wiley Periodicals, Inc.

A field trip guide to the petrology of Quaternary volcanism on the Yellowstone Plateau

USGS Publications Warehouse

Vazquez, Jorge A.; Stelten, Mark; Bindeman, Ilya N.; Cooper, Kari

2017-12-19

The Yellowstone Plateau is one of the largest manifestations of silicic volcanism on Earth, and marks the youngest focus of magmatism associated with the Yellowstone Hot Spot. The earliest products of Yellowstone Hot Spot volcanism are from ~17 million years ago, but may be as old as ~32 Ma, and include contemporaneous eruption of voluminous mafic and silicic magmas, which are mostly located in the region of northwestern Nevada and southeastern Oregon. Since 17 Ma, the main locus of Yellowstone Hot Spot volcanism has migrated northeastward producing numerous silicic caldera complexes that generally remain active for ~2–4 million years, with the present-day focus being the Yellowstone Plateau. Northeastward migration of volcanism associated with the Yellowstone Hot Spot resulted in the formation of the Snake River Plain, a low relief physiographic feature extending ~750 kilometers from northern Nevada to eastern Idaho. Most of the silicic volcanic centers along the Snake River Plain have been inundated by younger basalt volcanism, but many of their ignimbrites and lava flows are exposed in the extended regions at the margins of the Snake River Plain. 

Five-way smoking status classification using text hot-spot identification and error-correcting output codes.

PubMed

Cohen, Aaron M

2008-01-01

We participated in the i2b2 smoking status classification challenge task. The purpose of this task was to evaluate the ability of systems to automatically identify patient smoking status from discharge summaries. Our submission included several techniques that we compared and studied, including hot-spot identification, zero-vector filtering, inverse class frequency weighting, error-correcting output codes, and post-processing rules. We evaluated our approaches using the same methods as the i2b2 task organizers, using micro- and macro-averaged F1 as the primary performance metric. Our best performing system achieved a micro-F1 of 0.9000 on the test collection, equivalent to the best performing system submitted to the i2b2 challenge. Hot-spot identification, zero-vector filtering, classifier weighting, and error correcting output coding contributed additively to increased performance, with hot-spot identification having by far the largest positive effect. High performance on automatic identification of patient smoking status from discharge summaries is achievable with the efficient and straightforward machine learning techniques studied here.

Jobs and the resource curse in the sun: The effects of oil production on female labor force participation in California counties from 1980-2010

NASA Astrophysics Data System (ADS)

Zavala, Gabriel

This study aims to evaluate the relationship between oil income and the female labor force participation rate in California for the years of 1980, 1990, 2000 and 2010 using panel linear regression models. This study also aims to visualize the spatial patterns of both variables in California through Hot Spot analysis at the county level for the same years. The regression found no sign of a relationship between oil income and female labor force participation rate but did find evidence of a positive relationship between two income control variables and the female labor force participation rate. The hot spot analysis also found that female labor force participation cold spots are not spatially correlated with oil production hot spots. These findings contribute new methodologies at a finer scale to the very nuanced discussion of the resource curse in the United States.

Variation in the Water and Ammonia Abundance in Jupiter’s North Equatorial Belt

NASA Astrophysics Data System (ADS)

Bjoraker, Gordon L.; de Pater, Imke; Wong, Michael H.; Adamkovics, Mate; Hewagama, Tilak; Orton, Glenn

2017-10-01

We used iSHELL on NASA’s Infrared Telescope Facility and NIRSPEC on the Keck telescope concurrent with Juno perijoves 4-6 between February and May 2017 to obtain 5-micron spectra of Jupiter. Here we will focus on observations of the North Equatorial Belt. Spectrally resolved line profiles of CH3D, NH3, and H2O probe the 1 to 8-bar level of Jupiter’s troposphere. This overlaps with the weighting functions for several channels of Juno’s microwave radiometer. The profile of the CH3D lines at 4.66 microns is very broad in Hot Spots due to collisions with up to 8 bars of H2, where unit optical depth occurs due to collision-induced H2 opacity. The extreme width of these CH3D features implies that the Hot Spots that we observed do not have significant cloud opacity for P > 2 bars. We will discuss the abundance of NH3 and gaseous H2O within Hot Spots and other regions near the longitude of perijove for each Juno encounter. We had dry nights on Mauna Kea and a sufficient Doppler shift to detect H2O. We will compare line wings to derive H2O profiles in the 2 to 6-bar region. NEB Hot Spots are depleted in NH3 with respect to adjacent regions, especially for P < 2 bars. NEB Hot Spots are highly depleted in H2O for P < 5 bars.

The problem is not just sample size: the consequences of low base rates in policing experiments in smaller cities.

PubMed

Hinkle, Joshua C; Weisburd, David; Famega, Christine; Ready, Justin

2013-01-01

Hot spots policing is one of the most influential police innovations, with a strong body of experimental research showing it to be effective in reducing crime and disorder. However, most studies have been conducted in major cities, and we thus know little about whether it is effective in smaller cities, which account for a majority of police agencies. The lack of experimental studies in smaller cities is likely in part due to challenges designing statistically powerful tests in such contexts. The current article explores the challenges of statistical power and "noise" resulting from low base rates of crime in smaller cities and provides suggestions for future evaluations to overcome these limitations. Data from a randomized experimental evaluation of broken windows policing in hot spots are used to illustrate the challenges that low base rates present for evaluating hot spots policing programs in smaller cities. Analyses show low base rates make it difficult to detect treatment effects. Very large effect sizes would be required to reach sufficient power, and random fluctuations around low base rates make detecting treatment effects difficult, irrespective of power, by masking differences between treatment and control groups. Low base rates present strong challenges to researchers attempting to evaluate hot spots policing in smaller cities. As such, base rates must be taken directly into account when designing experimental evaluations. The article offers suggestions for researchers attempting to expand the examination of hot spots policing and other microplace-based interventions to smaller jurisdictions.

New Fks hot spot for acquired echinocandin resistance in Saccharomyces cerevisiae and its contribution to intrinsic resistance of Scedosporium species.

PubMed

Johnson, Michael E; Katiyar, Santosh K; Edlind, Thomas D

2011-08-01

Echinocandins represent a new antifungal group with potent activity against Candida species. These lipopeptides inhibit the synthesis of β-1,3-glucan, the major cell wall polysaccharide. Acquired resistance or reduced echinocandin susceptibility (RES) is rare and associated with mutations in two "hot spot" regions of Fks1 or Fks2, the probable β-1,3-glucan synthases. In contrast, many fungi demonstrate intrinsic RES for reasons that remain unclear. We are using Saccharomyces cerevisiae to understand the basis for RES by modeling echinocandin-Fks interaction. Previously characterized mutations confer cross-RES; we screened for mutations conferring differential RES, implying direct interaction of that Fks residue with a variable echinocandin side chain. One mutant (in an fks1Δ background) exhibited ≥16-fold micafungin and anidulafungin versus caspofungin RES. Sequencing identified a novel Fks2 mutation, W714L/Y715N. Equivalent W695L/Y696N and related W695L/F/C mutations in Fks1 generated by site-directed mutagenesis and the isolation of a W695L-equivalent mutation in Candida glabrata confirmed the role of the new "hot spot 3" in RES. Further mutagenesis expanded hot spot 3 to Fks1 residues 690 to 700, yielding phenotypes ranging from cross-RES to differential hypersusceptibility. Fks1 sequences from intrinsically RES Scedosporium species revealed W695F-equivalent substitutions; Fks1 hybrids expressing Scedosporium prolificans hot spot 3 confirmed that this substitution imparts RES.

Effects of void anisotropy on the ignition and growth rates of energetic materials

NASA Astrophysics Data System (ADS)

Rai, Nirmal Kumar; Sen, Oishik; Udaykumar, H. S.

2017-06-01

Initiation of heterogeneous energetic materials is thought to occur at hot spots; reaction fronts propagate from sites of such hot spots into the surrounding material resulting in complete consumption of the material. Heterogeneous materials, such as plastic bonded explosives (PBXs) and pressed materials contain numerous voids, defects and interfaces at which hot spots can occur. Amongst the various mechanisms of hot spot formation, void collapse is considered to be the predominant one in the high strain rate loading conditions. It is established in the past the shape of the voids has a significant effect on the initiation behavior of energetic materials. In particular, void aspect ratio and orientations play an important role in this regard. This work aims to quantify the effects of void aspect ratio and orientation on the ignition and growth rates of chemical reaction from the hot spot. A wide range of aspect ratio and orientations is considered to establish a correlation between the ignition and growth rates and the void morphology. The ignition and growth rates are obtained from high fidelity reactive meso-scale simulations. The energetic material considered in this work is HMX and Tarver McGuire HMX decomposition model is considered to capture the reaction mechanism of HMX. The meso-scale simulations are performed using a Cartesian grid based Eulerian solver SCIMITAR3D. The void morphology is shown to have a significant effect on the ignition and growth rates of HMX.

Material influence on hot spot distribution in the nanoparticle heterodimer on film

NASA Astrophysics Data System (ADS)

Chen, Fang; Huang, Yingzhou; Wei, Hua; Wang, Shuxia; Zeng, Xiping; Cao, Wenbin; Wen, Weijia

2018-04-01

The metal nanoparticle aggregated on film, as an effective plasma enhancement pathway, has been widely used in various surface plasmon-related fields. In this study, the hot spots on the metal nanoparticle dimer composed of different materials (Agsbnd Au, Agsbnd Pd, and Agsbnd Cu) on metal (Au) film were investigated with finite element method. Based on the results, the hot spot distribution affected by the material can be confirmed by the electric field distribution of the metal nanoparticle dimer on the film. The aggregation effects of Au and Ag nanoparticles in Ausbnd Ag dimer system are not significant. However, for the Pdsbnd Ag dimer system, the hot spot aggregation effect is slightly larger than that of the Pd nanoparticle under the Ag nanoparticle. Besides, the non-uniform hot spots would bring about the light focusing phenomenon that the light intensity under Ag nanoparticle is almost 100 times greater than that under Cu nanoparticle in Agsbnd Cu dimer system. These results were further confirmed by the surface charge distribution, and analyzed based on the plasmonic hybridization theory. The data about the nanoparticle dimer on the dielectric (Si) film demonstrate the importance of induced image charges on the film surface in such a light focusing phenomenon. Our findings can enhance the understanding of the surface plasmon coupling in different materials, which may have great application prospects in surface plasmon-related fields, such as SERS, plasmonic enhanced solar cell, and plasmonic sensoring, etc.

Analysis of Binding Site Hot Spots on the Surface of Ras GTPase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buhrman, Greg; O; #8242

2012-09-17

We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the 'off' and 'on' allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond themore » active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target.« less

Development of a Model to Predict the Primary Infection Date of Bacterial Spot (Xanthomonas campestris pv. vesicatoria) on Hot Pepper.

PubMed

Kim, Ji-Hoon; Kang, Wee-Soo; Yun, Sung-Chul

2014-06-01

A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds 10(15) cells/g within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required.

Development of a Model to Predict the Primary Infection Date of Bacterial Spot (Xanthomonas campestris pv. vesicatoria) on Hot Pepper

PubMed Central

Kim, Ji-Hoon; Kang, Wee-Soo; Yun, Sung-Chul

2014-01-01

A population model of bacterial spot caused by Xanthomonas campestris pv. vesicatoria on hot pepper was developed to predict the primary disease infection date. The model estimated the pathogen population on the surface and within the leaf of the host based on the wetness period and temperature. For successful infection, at least 5,000 cells/ml of the bacterial population were required. Also, wind and rain were necessary according to regression analyses of the monitored data. Bacterial spot on the model is initiated when the pathogen population exceeds 1015 cells/g within the leaf. The developed model was validated using 94 assessed samples from 2000 to 2007 obtained from monitored fields. Based on the validation study, the predicted initial infection dates varied based on the year rather than the location. Differences in initial infection dates between the model predictions and the monitored data in the field were minimal. For example, predicted infection dates for 7 locations were within the same month as the actual infection dates, 11 locations were within 1 month of the actual infection, and only 3 locations were more than 2 months apart from the actual infection. The predicted infection dates were mapped from 2009 to 2012; 2011 was the most severe year. Although the model was not sensitive enough to predict disease severity of less than 0.1% in the field, our model predicted bacterial spot severity of 1% or more. Therefore, this model can be applied in the field to determine when bacterial spot control is required. PMID:25288995

High-resolution melting analysis of the single nucleotide polymorphism hot-spot region in the rpoB gene as an indicator of reduced susceptibility to rifaximin in Clostridium difficile.

PubMed

Pecavar, Verena; Blaschitz, Marion; Hufnagl, Peter; Zeinzinger, Josef; Fiedler, Anita; Allerberger, Franz; Maass, Matthias; Indra, Alexander

2012-06-01

Clostridium difficile, a Gram-positive, spore-forming, anaerobic bacterium, is the main causative agent of hospital-acquired diarrhoea worldwide. In addition to metronidazole and vancomycin, rifaximin, a rifamycin derivative, is a promising antibiotic for the treatment of recurring C. difficile infections (CDI). However, exposure of C. difficile to this antibiotic has led to the development of rifaximin-resistance due to point mutations in the β-subunit of the RNA polymerase (rpoB) gene. In the present study, 348 C. difficile strains with known PCR-ribotypes were investigated for respective single nucleotide polymorphisms (SNPs) within the proposed rpoB hot-spot region by using high-resolution melting (HRM) analysis. This method allows the detection of SNPs by comparing the altered melting behaviour of dsDNA with that of wild-type DNA. Discrimination between wild-type and mutant strains was enhanced by creating heteroduplexes by mixing sample DNA with wild-type DNA, leading to characteristic melting curve shapes from samples containing SNPs in the respective rpoB section. In the present study, we were able to identify 16 different rpoB sequence-types (ST) by sequencing analysis of a 325 bp fragment. The 16 PCR STs displayed a total of 24 different SNPs. Fifteen of these 24 SNPs were located within the proposed 151 bp SNP hot-spot region, resulting in 11 different HRM curve profiles (CP). Eleven SNPs (seven of which were within the proposed hot-spot region) led to amino acid substitutions associated with reduced susceptibility to rifaximin and 13 SNPs (eight of which were within the hot-spot region) were synonymous. This investigation clearly demonstrates that HRM analysis of the proposed SNP hot-spot region in the rpoB gene of C. difficile is a fast and cost-effective method for the identification of C. difficile samples with reduced susceptibility to rifaximin and even allows simultaneous SNP subtyping of the respective C. difficile isolates.

Analysis of Biological Features Associated with Meiotic Recombination Hot and Cold Spots in Saccharomyces cerevisiae

PubMed Central

Hansen, Loren; Kim, Nak-Kyeong; Mariño-Ramírez, Leonardo; Landsman, David

2011-01-01

Meiotic recombination is not distributed uniformly throughout the genome. There are regions of high and low recombination rates called hot and cold spots, respectively. The recombination rate parallels the frequency of DNA double-strand breaks (DSBs) that initiate meiotic recombination. The aim is to identify biological features associated with DSB frequency. We constructed vectors representing various chromatin and sequence-based features for 1179 DSB hot spots and 1028 DSB cold spots. Using a feature selection approach, we have identified five features that distinguish hot from cold spots in Saccharomyces cerevisiae with high accuracy, namely the histone marks H3K4me3, H3K14ac, H3K36me3, and H3K79me3; and GC content. Previous studies have associated H3K4me3, H3K36me3, and GC content with areas of mitotic recombination. H3K14ac and H3K79me3 are novel predictions and thus represent good candidates for further experimental study. We also show nucleosome occupancy maps produced using next generation sequencing exhibit a bias at DSB hot spots and this bias is strong enough to obscure biologically relevant information. A computational approach using feature selection can productively be used to identify promising biological associations. H3K14ac and H3K79me3 are novel predictions of chromatin marks associated with meiotic DSBs. Next generation sequencing can exhibit a bias that is strong enough to lead to incorrect conclusions. Care must be taken when interpreting high throughput sequencing data where systematic biases have been documented. PMID:22242140

Real-time person detection in low-resolution thermal infrared imagery with MSER and CNNs

NASA Astrophysics Data System (ADS)

Herrmann, Christian; Müller, Thomas; Willersinn, Dieter; Beyerer, Jürgen

2016-10-01

In many camera-based systems, person detection and localization is an important step for safety and security applications such as search and rescue, reconnaissance, surveillance, or driver assistance. Long-wave infrared (LWIR) imagery promises to simplify this task because it is less affected by background clutter or illumination changes. In contrast to a lot of related work, we make no assumptions about any movement of persons or the camera, i.e. persons may stand still and the camera may move or any combination thereof. Furthermore, persons may appear arbitrarily in near or far distances to the camera leading to low-resolution persons in far distances. To address this task, we propose a two-stage system, including a proposal generation method and a classifier to verify, if the detected proposals really are persons. In contradiction to use all possible proposals as with sliding window approaches, we apply Maximally Stable Extremal Regions (MSER) and classify the detected proposals afterwards with a Convolutional Neural Network (CNN). The MSER algorithm acts as a hot spot detector when applied to LWIR imagery. Because the body temperature of persons is usually higher than the background, they appear as hot spots in the image. However, the MSER algorithm is unable to distinguish between different kinds of hot spots. Thus, all further LWIR sources such as windows, animals or vehicles will be detected, too. Still by applying MSER, the number of proposals is reduced significantly in comparison to a sliding window approach which allows employing the high discriminative capabilities of deep neural networks classifiers that were recently shown in several applications such as face recognition or image content classification. We suggest using a CNN as classifier for the detected hot spots and train it to discriminate between person hot spots and all further hot spots. We specifically design a CNN that is suitable for the low-resolution person hot spots that are common with LWIR imagery applications and is capable of fast classification. Evaluation on several different LWIR person detection datasets shows an error rate reduction of up to 80 percent compared to previous approaches consisting of MSER, local image descriptors and a standard classifier such as an SVM or boosted decision trees. Further time measurements show that the proposed processing chain is capable of real-time person detection in LWIR camera streams.

Legal space for syringe exchange programs in hot spots of injection drug use-related crime.

PubMed

Allen, Sean T; Ruiz, Monica S; Jones, Jeff; Turner, Monique M

2016-04-26

Copious evidence indicates that syringe exchange programs (SEPs) are effective structural interventions for HIV prevention among persons who inject drugs (PWID). The efficacy of SEPs in supporting the public health needs of PWID populations is partially dependent on their accessibility and consistent utilization among injectors. Research has shown that SEP access is an important predictor of PWID retention at SEPs, yet policies exist that may limit the geographic areas where SEP operations may legally occur. Since 2000 in the District of Columbia (DC), SEP operations have been subject to the 1000 Foot Rule (§48-1121), a policy that prohibits the distribution of "any needle or syringe for the hypodermic injection of any illegal drug in any area of the District of Columbia which is within 1000 feet of a public or private elementary or secondary school (including a public charter school)." The 1000 Foot Rule may impede SEP services in areas that are in urgent need for harm reduction services, such as locations where injections are happening in "real time" or where drugs are purchased or exchanged. We examined the effects of the 1000 Foot Rule on SEP operational space in injection drug use (IDU)-related crime (i.e., heroin possession or distribution) hot spots from 2000 to 2010. Data from the DC Metropolitan Police Department were used to identify IDU-related crime hot spots. School operation data were matched to a dataset that described the approximate physical property boundaries of land parcels. A 1000-ft buffer was applied to all school property boundaries. The overlap between the IDU-related crime hot spots and the school buffer zones was calculated by academic year. When overlaying the land space associated with IDU-related crime hot spots on the maps of school boundaries per the 1000-ft buffer zone stipulation, we found that the majority of land space in these locations was ineligible for legal SEP operations. More specifically, the ineligible space in the identified hot spots in each academic year ranged from 51.93 to 88.29 % of the total hot spot area. The removal of the 1000 Foot Rule could significantly improve the public health of PWID via increased access to harm reduction services. Buffer zone policies that restrict SEP operational space negatively affect the provision of harm reduction services to PWID.

Cold-spotting: linking primary care and public health to create communities of solution.

PubMed

Westfall, John M

2013-01-01

By providing enhanced primary care and social services to patients with high utilization of expensive emergency and hospital care, there is evidence that their health can improve and their costs can be lowered. This type of "hot-spotting" improves the care of individual patients. It may be that these patients live in communities with disintegrated social determinants of health, little community support, and poor access to primary care. These "cold spots" in the community may be amenable to interventions targeted at linking primary care and public health at broader community and population levels. Building local communities of solution that address the individual and population may help decrease these cold spots, thereby eliminating the hot spots as well.

A spatial analysis of population dynamics and climate change in Africa: potential vulnerability hot spots emerge where precipitation declines and demographic pressures coincide

USGS Publications Warehouse

López-Carr, David; Pricope, Narcisa G.; Aukema, Juliann E.; Jankowska, Marta M.; Funk, Christopher C.; Husak, Gregory J.; Michaelsen, Joel C.

2014-01-01

We present an integrative measure of exposure and sensitivity components of vulnerability to climatic and demographic change for the African continent in order to identify “hot spots” of high potential population vulnerability. Getis-Ord Gi* spatial clustering analyses reveal statistically significant locations of spatio-temporal precipitation decline coinciding with high population density and increase. Statistically significant areas are evident, particularly across central, southern, and eastern Africa. The highly populated Lake Victoria basin emerges as a particularly salient hot spot. People located in the regions highlighted in this analysis suffer exceptionally high exposure to negative climate change impacts (as populations increase on lands with decreasing rainfall). Results may help inform further hot spot mapping and related research on demographic vulnerabilities to climate change. Results may also inform more suitable geographical targeting of policy interventions across the continent.

Analyses of Transistor Punchthrough Failures

NASA Technical Reports Server (NTRS)

Nicolas, David P.

1999-01-01

The failure of two transistors in the Altitude Switch Assembly for the Solid Rocket Booster followed by two additional failures a year later presented a challenge to failure analysts. These devices had successfully worked for many years on numerous missions. There was no history of failures with this type of device. Extensive checks of the test procedures gave no indication for a source of the cause. The devices were manufactured more than twenty years ago and failure information on this lot date code was not readily available. External visual exam, radiography, PEID, and leak testing were performed with nominal results Electrical testing indicated nearly identical base-emitter and base-collector characteristics (both forward and reverse) with a low resistance short emitter to collector. These characteristics are indicative of a classic failure mechanism called punchthrough. In failure analysis punchthrough refers to an condition where a relatively low voltage pulse causes the device to conduct very hard producing localized areas of thermal runaway or "hot spots". At one or more of these hot spots, the excessive currents melt the silicon. Heavily doped emitter material diffuses through the base region to the collector forming a diffusion pipe shorting the emitter to base to collector. Upon cooling, an alloy junction forms between the pipe and the base region. Generally, the hot spot (punch-through site) is under the bond and no surface artifact is visible. The devices were delidded and the internal structures were examined microscopically. The gold emitter lead was melted on one device, but others had anomalies in the metallization around the in-tact emitter bonds. The SEM examination confirmed some anomalies to be cosmetic defects while other anomalies were artifacts of the punchthrough site. Subsequent to these analyses, the contractor determined that some irregular testing procedures occurred at the time of the failures heretofore unreported. These testing irregularities involved the use of a breakout box and were the likely cause of the failures. There was no evidence to suggest a generic failure mechanism was responsible for the failure of these transistors.

On beyond the standard model for high explosives: challenges & obstacles to surmount

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menikoff, Ralph Ds

2009-01-01

Plastic-bonded explosives (PBX) are heterogeneous materials. Nevertheless, current explosive models treat them as homogeneous materials. To compensate, an empirically determined effective burn rate is used in place of a chemical reaction rate. A significant limitation of these models is that different burn parameters are needed for applications in different regimes; for example, shock initiation of a PBX at different initial temperatures or different initial densities. This is due to temperature fluctuations generated when a heterogeneous material is shock compressed. Localized regions of high temperatures are called hot spots. They dominate the reaction for shock initiation. The understanding of hot spotmore » generation and their subsequent evolution has been limited by the inability to measure transients on small spatial ({approx} 1 {micro}m) and small temporal ({approx} 1 ns) scales in the harsh environment of a detonation. With the advances in computing power, it is natural to try and gain an understanding of hot-spot initiation with numerical experiments based on meso-scale simulations that resolve material heterogeneities and utilize realistic chemical reaction rates. However, to capture the underlying physics correctly, such high resolution simulations will require more than fast computers with a large amount of memory. Here we discuss some of the issues that need to be addressed. These include dissipative mechanisms that generate hot spots, accurate thermal propceties for the equations of state of the reactants and products, and controlling numerical entropy error from shock impedance mismatches at material interfaces. The later can generate artificial hot spots and lead to premature reaction. Eliminating numerical hot spots is critical for shock initiation simulations due to the positive feedback between the energy release from reaction and the hydrodynamic flow.« less

Variability of Jupiter's Five-Micron Hot Spot Inventory

NASA Technical Reports Server (NTRS)

Yanamandra-Fisher, Padma A.; Orton, G. S.; Wakefield, L.; Rogers, J. H.; Simon-Miller, A. A.; Boydstun, K.

2012-01-01

Global upheavals on Jupiter involve changes in the albedo of entire axisymmetric regions, lasting several years, with the last two occurring in 1989 and 2006. Against this backdrop of planetary-scale changes, discrete features such as the Great Red Spot (GRS), and other vortices exhibit changes on shorter spatial- and time-scales. We track the variability of the discrete equatorial 5-micron hot spots, semi-evenly spaced in longitude and confined to a narrow latitude band centered at 6.5degN (southern edge of the North Equatorial Belt, NEB), abundant in Voyager images. Tantalizingly similar patterns were observed in the visible (bright plumes and blue-gray regions), where reflectivity in the red is anti-correlated with 5-microns thermal radiance. Ortiz et al. (1998, GRL, 103) characterized the latitude and drift rates of the hot spots, including the descent of the Galileo probe at the southern edge of a 5-micron hot spot, as the superposition of equatorial Rossby waves, with phase speeds between 99 - 103m/s, relative to System III. We note that the high 5-micron radiances correlate well but not perfectly with high 8.57-micron radiances. Because the latter are modulated primarily by changes in the upper ammonia (NH3) ice cloud opacity, this correlation implies that changes in the ammonia ice cloud field may be responsible for the variability seen in the 5-m maps. During the NEB fade (2011 - early 2012), however, these otherwise ubiquitous features were absent, an atmospheric state not seen in decades. The ongoing NEB revival indicates nascent 5-m hot spots as early as April 2012, with corresponding visible dark spots. Their continuing growth through July 2012 indicates the possit.le re-establishment of Rossby waves. The South Equatorial Belt (SEB) and NEB revivals began similarly with an instability that developed into a major outbreak, and many similarities in the observed propagation of clear regions.

75 FR 14259 - Transportation Conformity Rule PM2.5

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-24

... NAAQS. In addition, EPA is clarifying the regulations concerning hot-spot analyses to address a December... the Revocation of the Annual PM 10 NAAQS IX. Response to the December 2007 Hot-Spot Court Decision X... public docket for this action under Docket ID No. EPA-HQ-OAR-2008-0540. You can get a paper copy of this...

Infrared speckle interferometry and spectroscopy of Io

NASA Technical Reports Server (NTRS)

Howell, Robert R.

1991-01-01

Observations of a series of mutual events of the Galilean satellites occurring in early 1991 are providing high resolution information concerning the volcanic hot spots on Jupiter's moon Io. The brightness of Io is plotted as a function of time as it is occulted by Europa. Voyager derived globes are given and interpreted, giving special attention to observed hot spots.

40 CFR 93.123 - Procedures for determining localized CO, PM10, and PM2.5 concentrations (hot-spot analysis).

Code of Federal Regulations, 2014 CFR

2014-07-01

... PM2.5 violations”) must be based on quantitative analysis using the applicable air quality models... either: (i) Quantitative methods that represent reasonable and common professional practice; or (ii) A...) The hot-spot demonstration required by § 93.116 must be based on quantitative analysis methods for the...

PILOT-SCALE INCINERATION OF PCB-CONTAMINATED SEDIMENTS FROM THE HOT SPOT OF THE NEW BEDFORD HARBOR SUPERFUND SITE

EPA Science Inventory

Testing was performed at the EPA's Incineration Research Facility (IRF) to determine the incinerability of contaminated marine sediment from the Hot Spot in the New Bedford Harbor Superfund Site. he contaminants at this site were PCBs, at concentration up to >200,000 mg/kb, and m...

Influence of Hot SPOT Features on the Shock Initiation of Heterogeneous Nitromethane

NASA Astrophysics Data System (ADS)

Dattelbaum, D. M.; Sheffield, S. A.; Stahl, D. B.; Dattelbaum, A. M.

2009-12-01

"Hot spots," or regions of localized high temperature and pressure that arise during the shock compression of heterogeneous materials, are known to highly influence the initiation characteristics of explosives. By introducing controlled-size particles at known number densities into otherwise homogeneous explosives, details about hot spot criticality can be mapped for a given material. Here, we describe a series of gas gun-driven plate impact experiments on nitromethane loaded with 40 μm silica beads at 6 wt%. Through the use of embedded electromagnetic gauges, we have gained insight into the initiation mechanisms as a function of the input shock pressure, and present a Pop-plot for the mixture, which is further compared to neat nitromethane.

Fusion yield rate recovery by escaping hot-spot fast ions in the neighboring fuel layer

NASA Astrophysics Data System (ADS)

Tang, Xian-Zhu; McDevitt, C. J.; Guo, Zehua; Berk, H. L.

2014-02-01

Free-streaming loss by fast ions can deplete the tail population in the hot spot of an inertial confinement fusion (ICF) target. Escaping fast ions in the neighboring fuel layer of a cryogenic target can produce a surplus of fast ions locally. In contrast to the Knudsen layer effect that reduces hot-spot fusion reactivity due to tail ion depletion, the inverse Knudsen layer effect increases fusion reactivity in the neighboring fuel layer. In the case of a burning ICF target in the presence of significant hydrodynamic mix which aggravates the Knudsen layer effect, the yield recovery largely compensates for the yield reduction. For mix-dominated sub-ignition targets, the yield reduction is the dominant process.

Current redistribution and generation of kinetic energy in the stagnated Z pinch.

PubMed

Ivanov, V V; Anderson, A A; Papp, D; Astanovitskiy, A L; Talbot, B R; Chittenden, J P; Niasse, N

2013-07-01

The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%.

ELIPGRID-PC: A PC program for calculating hot spot probabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, J.R.

1994-10-01

ELIPGRID-PC, a new personal computer program has been developed to provide easy access to Singer`s 1972 ELIPGRID algorithm for hot-spot detection probabilities. Three features of the program are the ability to determine: (1) the grid size required for specified conditions, (2) the smallest hot spot that can be sampled with a given probability, and (3) the approximate grid size resulting from specified conditions and sampling cost. ELIPGRID-PC also provides probability of hit versus cost data for graphing with spread-sheets or graphics software. The program has been successfully tested using Singer`s published ELIPGRID results. An apparent error in the original ELIPGRIDmore » code has been uncovered and an appropriate modification incorporated into the new program.« less

The role of hot spot mix in the low-foot and high-foot implosions on the NIF

NASA Astrophysics Data System (ADS)

Ma, T.; Patel, P. K.; Izumi, N.; Springer, P. T.; Key, M. H.; Atherton, L. J.; Barrios, M. A.; Benedetti, L. R.; Bionta, R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C. J.; Church, J. A.; Clark, D. S.; Dewald, E. L.; Dittrich, T. R.; Dixit, S. N.; Döppner, T.; Dylla-Spears, R.; Edgell, D. H.; Epstein, R.; Field, J.; Fittinghoff, D. N.; Frenje, J. A.; Gatu Johnson, M.; Glenn, S.; Glenzer, S. H.; Grim, G.; Guler, N.; Haan, S. W.; Hammel, B. A.; Hatarik, R.; Herrmann, H. W.; Hicks, D.; Hinkel, D. E.; Berzak Hopkins, L. F.; Hsing, W. W.; Hurricane, O. A.; Jones, O. S.; Kauffman, R.; Khan, S. F.; Kilkenny, J. D.; Kline, J. L.; Kozioziemski, B.; Kritcher, A.; Kyrala, G. A.; Landen, O. L.; Lindl, J. D.; Le Pape, S.; MacGowan, B. J.; Mackinnon, A. J.; MacPhee, A. G.; Meezan, N. B.; Merrill, F. E.; Moody, J. D.; Moses, E. I.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Park, H.-S.; Ralph, J. E.; Regan, S. P.; Remington, B. A.; Robey, H. F.; Rosen, M. D.; Rygg, J. R.; Ross, J. S.; Salmonson, J. D.; Sater, J.; Sayre, D.; Schneider, M. B.; Shaughnessy, D.; Sio, H.; Spears, B. K.; Smalyuk, V.; Suter, L. J.; Tommasini, R.; Town, R. P. J.; Volegov, P. L.; Wan, A.; Weber, S. V.; Widmann, K.; Wilde, C. H.; Yeamans, C.; Edwards, M. J.

2017-05-01

Hydrodynamic mix of the ablator into the DT fuel layer and hot spot can be a critical performance limitation in inertial confinement fusion implosions. This mix results in increased radiation loss, cooling of the hot spot, and reduced neutron yield. To quantify the level of mix, we have developed a simple model that infers the level of contamination using the ratio of the measured x-ray emission to the neutron yield. The principal source for the performance limitation of the "low-foot" class of implosions appears to have been mix. Lower convergence "high-foot" implosions are found to be less susceptible to mix, allowing velocities of >380 km/s to be achieved.

Hot Spots from Generated Defects in HMX Crystals

NASA Astrophysics Data System (ADS)

Sorensen, Christian; Cummock, Nicholas; O'Grady, Caitlin; Gunduz, I. Emre; Son, Steven

2017-06-01

There are several hot spot initiation mechanisms that have been proposed. However, direct observation of shock or impact compression of these mechanisms at macroscopic scale in explosives is difficult. Phase contrast imaging (PCI) may be applied to these systems. Here, high-speed video was used to record optical spectrum and for x-ray Phase Contrast Imaging (PCI) of shockwave interaction with low defect HMX crystals and crystals with engineered defects. Additionally, multiple crystals were arranged and observed under shock loading with PCI and optical high-speed video. Sample preparation techniques for generating voids and other engineered defects will be discussed. These methods include drilled holes and laser machined samples. Insight into hot spot mechanisms was obtained. Funding from ONR's PC@Xtreme MURI.

Modeling of the hydrogen maser disk in MWC 349

NASA Astrophysics Data System (ADS)

Ponomarev, Victor O.; Smith, Howard A.; Strelnitski, Vladimir S.

1994-04-01

Maser amplification in a Keplerian circumstellar disk seen edge on-the idea put forward by Gordon (1992), Martin-Pintado, & Serabyn (1992), and Thum, Martin-Pintado, & Bachiller (1992) to explain the millimeter hydrogen recombination lines in MWC 349-is further justified and developed here. The double-peaked (vs. possible triple-peaked) form of the observed spectra is explained by the reduced emission from the inner portion of the disk, the portion responsible for the central ('zero velocity') component of a triple-peaked spectrum. Radial gradient of electron density and/or free-free absorption within the disk are identified as the probable causes of this central 'hole' in the disk and of its opacity. We calculate a set of synthetic maser spectra radiated by a homogeneous Keplerian ring seen edge-on and compare them to the H30-alpha observations of Thum et al., averaged over about 1000 days. We used a simple graphical procedure to solve an inverse problem and deduced the probable values of some basic disk and maser parameters. We find that the maser is essentially unsaturated, and that the most probable values of electron temperature. Doppler width of the microturbulence, and electron density, all averaged along the amplification path are, correspondingly, Te less than or equal to 11,000 K, Vmicro less than or equal to 14 km/s, ne approx. = (3 +/- 2) x 107/cu cm. The model shows that radiation at every frequency within the spectrum arises in a monochromatic 'hot spot.' The maximum optical depth within the 'hot spot' producing radiation at the spectral peak maximum is taumax approx. = 6 +/- 1; the effective width of the masing ring is approx. = 0.4-0.7 times its outer diameter; the size of the 'hot spot' responsible for the radiation at the spectral peak frequency is approx. = 0.2-0.3 times the distance between the two 'hot spots' corresponding to two peaks. An important derivation of our model is the dynamical mass of the central star, M* approx. = 26 solar masses (D/1.2 kpc), D being the distance to the star. Prospects for improving the model are discussed.

Mitigating road mortality of diamond-backed terrapins (Malaclemy's terrapin) with hybrid barriers at crossing hot spots

USGS Publications Warehouse

Crawford, Brian A.; Moore, Clinton; Norton, Terry M.; Maerz, John C.

2017-01-01

Roads represent a pervasive feature on most landscapes that can pose multiple threats to wildlife populations and substantial challenges for management. To be effective, management strategies must often target where threats are most concentrated. Road mortality and nest predation are well-documented threats to Diamond-backed Terrapins (Malaclemys terrapin) across the majority of their range, including the 8.7-km causeway to Jekyll Island, Georgia, USA, where both are predicted to contribute to population declines if left unmitigated. From 2009 to 2014, we used intensive road surveying to identify spatial peaks (hot spots) of terrapin crossing activity and road mortality and exploit these as targets for management. In 2011, we deployed a hybrid barrier composed of nest boxes, which were designed to prevent terrapins from accessing the road and mitigate nest predation, at one hot spot while leaving two other hot spots unmanaged. We evaluated the impact of the barrier on terrapin emergences on the causeway under a Before-After-Control-Impact (BACI) design, and a companion study evaluated the effects of nest boxes on nest predation rates. We estimated a 57% reduction in annual terrapin emergences at the barrier site compared to no measurable change at control hot spots. Our findings support the use of hybrid barriers for simultaneously addressing road mortality and nest predation for other terrapin populations at risk to these threats. Our approach highlights the need to design feasible but robust management strategies that target spatial peaks of road mortality while addressing additional threats contributing to population declines of terrapins and other species.

Origin of depleted components in basalt related to the Hawaiian hot spot: Evidence from isotopic and incompatible element ratios

NASA Astrophysics Data System (ADS)

Frey, F. A.; Huang, S.; Blichert-Toft, J.; Regelous, M.; Boyet, M.

2005-02-01

The radiogenic isotopic ratios of Sr, Nd, Hf, and Pb in basaltic lavas associated with major hot spots, such as Hawaii, document the geochemical heterogeneity of their mantle source. What processes created such heterogeneity? For Hawaiian lavas there has been extensive discussion of geochemically enriched source components, but relatively little attention has been given to the origin of depleted source components, that is, components with the lowest 87Sr/86Sr and highest 143Nd/144Nd and 176Hf/177Hf. The surprisingly important role of a depleted component in the source of the incompatible element-enriched, rejuvenated-stage Hawaiian lavas is well known. A depleted component also contributed significantly to the ˜76-81 Ma lavas erupted at Detroit Seamount in the Emperor Seamount Chain. In both cases, major involvement of MORB-related depleted asthenosphere or lithosphere has been proposed. Detroit Seamount and rejuvenated-stage lavas, however, have important isotopic differences from most Pacific MORB. Specifically, they define trends to relatively unradiogenic Pb isotope ratios, and most Emperor Seamount lavas define a steep trend of 176Hf/177Hf versus 143Nd/144Nd. In addition, lavas from Detroit Seamount and recent rejuvenated-stage lavas have relatively high Ba/Th, a characteristic of lavas associated with the Hawaiian hot spot. It is possible that a depleted component, intrinsic to the hot spot, has contributed to these young and old lavas related to the Hawaiian hot spot. The persistence of such a component over 80 Myr is consistent with a long-lived source, i.e., a plume.

Orbital Light Curves of UU Aquarii in Stunted Outburst

NASA Astrophysics Data System (ADS)

Robertson, J. W.; Honeycutt, R. K.; Henden, A. A.; Campbell, R. T.

2018-02-01

Stunted outbursts are ∼0.ͫ6 eruptions, typically lasting 5–10 days, which are found in some novalike cataclysmic variables, including UU Aqr. The mechanism responsible for stunted outbursts is uncertain but is likely related to an accretion disk instability or to variations in the mass transfer rate. A campaign to monitor the eclipse light curves in UU Aqr has been conducted in order to detect any light curve distortions due to the appearance of a hot spot on the disk at the location of the impact point of the accretion stream. If stunted outbursts are due to a temporary mass transfer enhancement, then predictable deformations of the orbital light curve are expected to occur during such outbursts. This study used 156 eclipses on 135 nights during the years 2000–2012. During this interval, random samples found the system to be in stunted outbursts 4%–5% of the time, yielding ∼7 eclipses obtained during some stage of stunted outburst. About half of the eclipses obtained during stunted outbursts showed clear evidence for hot spot enhancement, providing strong evidence that the stunted outbursts in UU Aqr are associated with mass transfer variations. The other half of the eclipses during stunted outburst showed little or no evidence for hot spot enhancement. Furthermore, there were no systematic changes in the hot spot signature as stunted outbursts progressed. Therefore, we have tentatively attributed the changes in hot spot visibility during stunted outburst to random blobby accretion, which likely further modulates the strength of the accretion stream on orbital timescales.

Interolog interfaces in protein–protein docking

PubMed Central

Alsop, James D.

2015-01-01

ABSTRACT Proteins are essential elements of biological systems, and their function typically relies on their ability to successfully bind to specific partners. Recently, an emphasis of study into protein interactions has been on hot spots, or residues in the binding interface that make a significant contribution to the binding energetics. In this study, we investigate how conservation of hot spots can be used to guide docking prediction. We show that the use of evolutionary data combined with hot spot prediction highlights near‐native structures across a range of benchmark examples. Our approach explores various strategies for using hot spots and evolutionary data to score protein complexes, using both absolute and chemical definitions of conservation along with refinements to these strategies that look at windowed conservation and filtering to ensure a minimum number of hot spots in each binding partner. Finally, structure‐based models of orthologs were generated for comparison with sequence‐based scoring. Using two data sets of 22 and 85 examples, a high rate of top 10 and top 1 predictions are observed, with up to 82% of examples returning a top 10 hit and 35% returning top 1 hit depending on the data set and strategy applied; upon inclusion of the native structure among the decoys, up to 55% of examples yielded a top 1 hit. The 20 common examples between data sets show that more carefully curated interolog data yields better predictions, particularly in achieving top 1 hits. Proteins 2015; 83:1940–1946. © 2015 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc. PMID:25740680

Hot SPOT Eclipses in Dwarf Novae

NASA Astrophysics Data System (ADS)

Smak, J.

1996-10-01

Eclipses of the hot spot in four dwarf novae: U Gem, IP Peg, Z Cha, and OY Car are re-analyzed, assuming two models for the shape of the spot. In Model 1 an elliptical spot is assumed, with the semi-axes s_a in the orbital plane and s_b perpendicular to the orbital plane, its center located on the stream trajectory. The results show that such an ellipse is, within errors, tangent to the disk's circumference. In all four cases the resulting dimensions of the spot s_a are larger than the theoretical cross-section of the stream. Accordingly, in Model2 the spot is assumed to consist of a head, centered on the stream trajectory, and a tail, extending downstream, ie., along disk's circumference. In some cases the resulting parameters, eg., mass ratios or disk radii, differ significantly from those obtained with Model 1.

40 CFR 93.109 - Criteria and procedures for determining conformity of transportation plans, programs, and...

Code of Federal Regulations, 2014 CFR

2014-07-01

... NAAQS. Paragraph (d) of this section explains when a hot-spot test is required. Paragraph (e) of this... insignificant motor vehicle emissions. Paragraph (g) of this section addresses isolated rural nonattainment and....5 hot-spots. § 93.117 PM10 and PM2.5 control measures Project (Not From a Conforming Plan and TIP...

40 CFR 93.109 - Criteria and procedures for determining conformity of transportation plans, programs, and...

Code of Federal Regulations, 2012 CFR

2012-07-01

... NAAQS. Paragraph (d) of this section explains when a hot-spot test is required. Paragraph (e) of this... insignificant motor vehicle emissions. Paragraph (g) of this section addresses isolated rural nonattainment and....5 hot-spots. § 93.117 PM10 and PM2.5 control measures Project (Not From a Conforming Plan and TIP...

40 CFR 93.109 - Criteria and procedures for determining conformity of transportation plans, programs, and...

Code of Federal Regulations, 2013 CFR

2013-07-01

... NAAQS. Paragraph (d) of this section explains when a hot-spot test is required. Paragraph (e) of this... insignificant motor vehicle emissions. Paragraph (g) of this section addresses isolated rural nonattainment and....5 hot-spots. § 93.117 PM10 and PM2.5 control measures Project (Not From a Conforming Plan and TIP...

75 FR 79370 - Official Release of the MOVES2010a and EMFAC2007 Motor Vehicle Emissions Models for...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-20

...: This Notice announces the availability of two new EPA guidance documents for: completing quantitative... of the MOVES model (MOVES2010a) for official use for quantitative CO, PM 2.5, and PM 10 hot-spot... emissions model is required to be used in quantitative CO and PM hot-spot analyses for project-level...

Controlled formation of intense hot spots in Pd@Ag core-shell nanooctapods for efficient photothermal conversion

NASA Astrophysics Data System (ADS)

Liu, Maochang; Yang, Yang; Li, Naixu; Du, Yuanchang; Song, Dongxing; Ma, Lijing; Wang, Yi; Zheng, Yiqun; Jing, Dengwei

2017-08-01

Plasmonic Ag nanostructures have been of great interest for such applications in cancer therapy and catalysis, etc. However, the relatively week Ag-Ag interaction and spontaneous atom diffusion make it very difficult to generate concaved or branched structures in Ag nanocrystals with sizes less than 100 nm, which has been considered very favorable for plasmonic effects. Herein, by employing a cubic Pd seed and a specific reducing agent to restrict the surface diffusion of Ag atoms, Pd@Ag core-shell nanooctapod structures where Ag atoms can be selectively deposited onto the corner sites of the Pd cubes were obtained. Such selective decoration enables us to precisely control the locations for the hot spot formation during light irradiation. We find that the branched nanooctapod structure shows strong absorption in the visible-light region and generates intense hot spots around the octapod arms of Ag. As such, the photothermal conversion efficiency could be significantly improved by more than 50% with a colloid solution containing only ppm-level nanooctapods compared with pure water. The reported nanostructure is expected to find extensive applications due to its controlled formation of light-induced hot spots at certain points on the crystal surface.

Deflagration Wave Profiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menikoff, Ralph

2012-04-03

Shock initiation in a plastic-bonded explosives (PBX) is due to hot spots. Current reactive burn models are based, at least heuristically, on the ignition and growth concept. The ignition phase occurs when a small localized region of high temperature (or hot spot) burns on a fast time scale. This is followed by a growth phase in which a reactive front spreads out from the hot spot. Propagating reactive fronts are deflagration waves. A key question is the deflagration speed in a PBX compressed and heated by a shock wave that generated the hot spot. Here, the ODEs for a steadymore » deflagration wave profile in a compressible fluid are derived, along with the needed thermodynamic quantities of realistic equations of state corresponding to the reactants and products of a PBX. The properties of the wave profile equations are analyzed and an algorithm is derived for computing the deflagration speed. As an illustrative example, the algorithm is applied to compute the deflagration speed in shock compressed PBX 9501 as a function of shock pressure. The calculated deflagration speed, even at the CJ pressure, is low compared to the detonation speed. The implication of this are briefly discussed.« less

p110α Hot Spot Mutations E545K and H1047R Exert Metabolic Reprogramming Independently of p110α Kinase Activity.

PubMed

Chaudhari, Aditi; Krumlinde, Daniel; Lundqvist, Annika; Akyürek, Levent M; Bandaru, Sashidhar; Skålén, Kristina; Ståhlman, Marcus; Borén, Jan; Wettergren, Yvonne; Ejeskär, Katarina; Rotter Sopasakis, Victoria

2015-10-01

The phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) catalytic subunit p110α is the most frequently mutated kinase in human cancer, and the hot spot mutations E542K, E545K, and H1047R are the most common mutations in p110α. Very little is known about the metabolic consequences of the hot spot mutations of p110α in vivo. In this study, we used adenoviral gene transfer in mice to investigate the effects of the E545K and H1047R mutations on hepatic and whole-body glucose metabolism. We show that hepatic expression of these hot spot mutations results in rapid hepatic steatosis, paradoxically accompanied by increased glucose tolerance, and marked glycogen accumulation. In contrast, wild-type p110α expression does not lead to hepatic accumulation of lipids or glycogen despite similar degrees of upregulated glycolysis and expression of lipogenic genes. The reprogrammed metabolism of the E545K and H1047R p110α mutants was surprisingly not dependent on altered p110α lipid kinase activity. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Cryogenic THD and DT layer implosions with high density carbon ablators in near-vacuum hohlraums

DOE PAGES

Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; ...

2015-06-02

High Density Carbon (HDC or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a DT layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a THD layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightlymore » oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 x 10¹⁵ neutrons, 40% of the 1D simulated yield.« less

Plasmonic Heterodimers with Binding Site-Dependent Hot Spot for Surface-Enhanced Raman Scattering.

PubMed

Tian, Yuanyuan; Shuai, Zhenhua; Shen, Jingjing; Zhang, Lei; Chen, Shufen; Song, Chunyuan; Zhao, Baomin; Fan, Quli; Wang, Lianhui

2018-06-01

A novel plasmonic heterodimer nanostructure with a controllable self-assembled hot spot is fabricated by the conjugation of individual Au@Ag core-shell nanocubes (Au@Ag NCs) and varisized gold nanospheres (GNSs) via the biotin-streptavidin interaction from the ensemble to the single-assembly level. Due to their featured configurations, three types of heterogeneous nanostructures referred to as Vertice, Vicinity, and Middle are proposed and a single hot spot forms between the nanocube and nanosphere, which exhibits distinct diversity in surface plasmon resonance effect. Herein, the calculated surface-enhanced Raman scattering enhancement factors of the three types of heterodimers show a narrow distribution and can be tuned in orders of magnitude by controlling the size of GNSs onto individual Au@Ag NCs. Particularly, the Vertice heterodimer with unique configuration can provide extraordinary enhancement of the electric field for the single hot spot region due to the collaborative interaction of lightning rod effect and interparticle plasmon coupling effect. This established relationship between the architecture and the corresponding optical properties of the heterodimers provides the basis for creating controllable platforms which can be exploited in the applications of plasmonic devices, electronics, and biodetection. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal feature extraction of servers in a datacenter using thermal image registration

NASA Astrophysics Data System (ADS)

Liu, Hang; Ran, Jian; Xie, Ting; Gao, Shan

2017-09-01

Thermal cameras provide fine-grained thermal information that enhances monitoring and enables automatic thermal management in large datacenters. Recent approaches employing mobile robots or thermal camera networks can already identify the physical locations of hot spots. Other distribution information used to optimize datacenter management can also be obtained automatically using pattern recognition technology. However, most of the features extracted from thermal images, such as shape and gradient, may be affected by changes in the position and direction of the thermal camera. This paper presents a method for extracting the thermal features of a hot spot or a server in a container datacenter. First, thermal and visual images are registered based on textural characteristics extracted from images acquired in datacenters. Then, the thermal distribution of each server is standardized. The features of a hot spot or server extracted from the standard distribution can reduce the impact of camera position and direction. The results of experiments show that image registration is efficient for aligning the corresponding visual and thermal images in the datacenter, and the standardization procedure reduces the impacts of camera position and direction on hot spot or server features.

Kinetic Energy Transfer Process in a Double Shell Leading to Robust Burn

NASA Astrophysics Data System (ADS)

Montgomery, D. S.; Daughton, W. S.; Albright, B. J.; Wilson, D. C.; Loomis, E. N.; Merritt, E. C.; Dodd, E. S.; Kirkpatrick, R. C.; Watt, R. G.; Rosen, M. D.

2017-10-01

A goal of double shell capsule implosions is to impart sufficient internal energy to the D-T fuel at stagnation in order to obtain robust α-heating and burn with low hot spot convergence, C.R. < 10. A simple description of the kinetic energy transfer from the outer shell to the inner shell is found using shock physics and adiabatic compression, and compares well with 1D modeling. An isobaric model for the stagnation phase of the inner shell is used to determine the ideal partition of internal energy in the D-T fuel. Robust burn of the fuel requires, at minimum, that α-heating exceeds the rate of cooling by expansion of the hot spot so that the yield occurs before the hot spot disassembles, which is then used to define a minimum requirement for robust burn. One potential advantage of a double shell capsule compared to single shell capsules is the use of a heavy metal pusher, which may lead to a longer hot spot disassembly time. We present these analytic results and compare them to 1D and 2D radiation-hydrodynamic simulations. Work performed under the auspices of DOE by LANL under contract DE-AC52-06NA25396.

Gravitational Evidence for a Low-Density Mass beneath the Galapagos Islands.

PubMed

Case, J E; Ryland, S L; Simkin, T; Howard, K A

1973-09-14

A residual negative free-air and Bouguer anomaly of at least 80 milligals, superimposed on a broader high, occurs over the Galápagos Islands The axis of the anomaly trends roughly east and plunges eastward. Thus, a low-density mass in the crust or upper mantle must underlie the archipelago. This anomaly may be caused by thermal expansion over a crust-mantle " hot spot".

The Saccharomyces cerevisiae MLH3 gene functions in MSH3-dependent suppression of frameshift mutations.

PubMed

Flores-Rozas, H; Kolodner, R D

1998-10-13

The Saccharomyces cerevisiae genome encodes four MutL homologs. Of these, MLH1 and PMS1 are known to act in the MSH2-dependent pathway that repairs DNA mismatches. We have investigated the role of MLH3 in mismatch repair. Mutations in MLH3 increased the rate of reversion of the hom3-10 allele by increasing the rate of deletion of a single T in a run of 7 Ts. Combination of mutations in MLH3 and MSH6 caused a synergistic increase in the hom3-10 reversion rate, whereas the hom3-10 reversion rate in an mlh3 msh3 double mutant was the same as in the respective single mutants. Similar results were observed when the accumulation of mutations at frameshift hot spots in the LYS2 gene was analyzed, although mutation of MLH3 did not cause the same extent of affect at every LYS2 frameshift hot spot. MLH3 interacted with MLH1 in a two-hybrid system. These data are consistent with the idea that a proportion of the repair of specific insertion/deletion mispairs by the MSH3-dependent mismatch repair pathway uses a heterodimeric MLH1-MLH3 complex in place of the MLH1-PMS1 complex.

Dynamic fracture and hot-spot modeling in energetic composites

NASA Astrophysics Data System (ADS)

Grilli, Nicolò; Duarte, Camilo A.; Koslowski, Marisol

2018-02-01

Defects such as cracks, pores, and particle-matrix interface debonding affect the sensitivity of energetic materials by reducing the time-to-ignition and the threshold pressure to initiate an explosion. Frictional sliding of preexisting cracks is considered to be one of the most important causes of localized heating. Therefore, understanding the dynamic fracture of crystalline energetic materials is of extreme importance to assess the reliability and safety of polymer-bonded explosives. Phase field damage model simulations, based on the regularization of the crack surface as a diffuse delta function, are used to describe crack propagation in cyclotetramethylene-tetranitramine crystals embedded in a Sylgard matrix. A thermal transport model that includes heat generation by friction at crack interfaces is coupled to the solution of crack propagation. 2D and 3D dynamic compression simulations are performed with different boundary velocities and initial distributions of cracks and interface defects to understand their effect on crack propagation and heat generation. It is found that, at an impact velocity of 400 m/s, localized damage at the particle-binder interface is of key importance and that the sample reaches temperatures high enough to create a hot-spot that will lead to ignition. At an impact velocity of 10 m/s, preexisting cracks advanced inside the particle, but the increase of temperature will not cause ignition.

Anomalous ultrafast dynamics of hot plasmonic electrons in nanostructures with hot spots

DOE PAGES

Harutyunyan, Hayk; Martinson, Alex B. F.; Rosenmann, Daniel; ...

2015-08-03

The interaction of light and matter in metallic nanosystems is mediated by the collective oscillation of surface electrons, called plasmons. After excitation, plasmons are absorbed by the metal electrons through inter- and intraband transitions, creating a highly non-thermal distribution of electrons. The electron population then decays through electron-electron interactions, creating a hot electron distribution within a few hundred femtoseconds, followed by a further relaxation via electron-phonon scattering on the timescale of a few pico-seconds. In the spectral domain, hot plasmonic electrons induce changes to the plasmonic resonance of the nanostructure by modifying the dielectric constant of the metal. Here, wemore » report on the observation of anomalously strong changes to the ultrafast temporal and spectral responses of these excited hot plasmonic electrons in hybrid metal/oxide nanostructures as a result of varying the geometry and composition of the nanostructure and the excitation wavelength. In particular, we show a large ultrafast, pulsewidth-limited contribution to the excited electron decay signal in hybrid nanostructures containing hot spots. The intensity of this contribution correlates with the efficiency of the generation of highly excited surface electrons. Using theoretical models, we attribute this effect to the generation of hot plasmonic electrons from hot spots. Finally, we then develop general principles to enhance the generation of energetic electrons through specifically designed plasmonic nanostructures that could be used in applications where hot electron generation is beneficial, such as in solar photocatalysis, photodetectors and nonlinear devices.« less

Anomalous ultrafast dynamics of hot plasmonic electrons in nanostructures with hot spots.

PubMed

Harutyunyan, Hayk; Martinson, Alex B F; Rosenmann, Daniel; Khorashad, Larousse Khosravi; Besteiro, Lucas V; Govorov, Alexander O; Wiederrecht, Gary P

2015-09-01

The interaction of light and matter in metallic nanosystems is mediated by the collective oscillation of surface electrons, called plasmons. After excitation, plasmons are absorbed by the metal electrons through inter- and intraband transitions, creating a highly non-thermal distribution of electrons. The electron population then decays through electron-electron interactions, creating a hot electron distribution within a few hundred femtoseconds, followed by a further relaxation via electron-phonon scattering on the timescale of a few picoseconds. In the spectral domain, hot plasmonic electrons induce changes to the plasmonic resonance of the nanostructure by modifying the dielectric constant of the metal. Here, we report on the observation of anomalously strong changes to the ultrafast temporal and spectral responses of these excited hot plasmonic electrons in hybrid metal/oxide nanostructures as a result of varying the geometry and composition of the nanostructure and the excitation wavelength. In particular, we show a large ultrafast, pulsewidth-limited contribution to the excited electron decay signal in hybrid nanostructures containing hot spots. The intensity of this contribution correlates with the efficiency of the generation of highly excited surface electrons. Using theoretical models, we attribute this effect to the generation of hot plasmonic electrons from hot spots. We then develop general principles to enhance the generation of energetic electrons through specifically designed plasmonic nanostructures that could be used in applications where hot electron generation is beneficial, such as in solar photocatalysis, photodetectors and nonlinear devices.

Hot-spot evolution and the global tectonics of Venus

NASA Astrophysics Data System (ADS)

Phillips, R. J.; Grimm, R. E.; Malin, M. C.

1991-05-01

The global tectonics of Venus may be dominated by plumes rising from the mantle and impinging on the lithosphere, giving rise to hot spots. Global sea-floor spreading does not take place, but direct convective coupling of mantle flow fields to the lithosphere leads to regional-scale deformation and may allow lithospheric transport on a limited scale. A hot-spot evolutionary sequence comprises (1) a broad domal uplift resulting from a rising mantle plume, (2) massive partial melting in the plume head and generation of a thickened crust or crustal plateau, (3) collapse of dynamic topography, and (4) creep spreading of the crustal plateau. Crust on Venus is produced by gradual vertical differentiation with little recycling rather than by the rapid horizontal creation and consumption characteristic of terrestrial sea-floor spreading.

Species separation and modification of neutron diagnostics in inertial-confinement fusion

NASA Astrophysics Data System (ADS)

Inglebert, A.; Canaud, B.; Larroche, O.

2014-09-01

The different behaviours of deuterium (D) and tritium (T) in the hot spot of marginally igniting cryogenic DT inertial-confinement fusion (ICF) targets are investigated with an ion Fokker-Planck model. With respect to an equivalent single-species model, a higher density and a higher temperature are found for T in the stagnation phase of the target implosion. In addition, the stagnating hot spot is found to be less dense but hotter than in the single-species case. As a result, the fusion reaction yield in the hot spot is significantly increased. Fusion neutron diagnostics of the implosion find a larger ion temperature as deduced from DT reactions than from DD reactions, in good agreement with NIF experimental results. ICF target designs should thus definitely take ion-kinetic effects into account.

Line formation in the hot spot region of cataclysmic variable accretion disks

NASA Technical Reports Server (NTRS)

Elitzur, Moshe; Clarke, John T.; Kallman, T. R.

1988-01-01

The paper presents a theoretical analysis of the emission lines observed in the cataclysmic variable A0 Psc (=H2252-035), including detailed modeling of the hydrogen Balmer line emission. The analysis makes it possible to deduce the physical conditions in the so called 'hot spot', or 'bulge' region where the accretion column hits the rim of the accretion disk. It is concluded that the bulge is optically thick to the ionizing disk radiation. Consequently, its disk illuminated face is fully ionized whereas the side facing away from the disk is neutral, resulting in modulation of the observed emission lines with the orbital period. The density in the hot spot is about 5 x 10 to the 12th to 10 to the 13th/cu cm.

Hot-spot evolution and the global tectonics of Venus

NASA Technical Reports Server (NTRS)

Phillips, Roger J.; Grimm, Robert E.; Malin, Michael C.

1991-01-01

The global tectonics of Venus may be dominated by plumes rising from the mantle and impinging on the lithosphere, giving rise to hot spots. Global sea-floor spreading does not take place, but direct convective coupling of mantle flow fields to the lithosphere leads to regional-scale deformation and may allow lithospheric transport on a limited scale. A hot-spot evolutionary sequence comprises (1) a broad domal uplift resulting from a rising mantle plume, (2) massive partial melting in the plume head and generation of a thickened crust or crustal plateau, (3) collapse of dynamic topography, and (4) creep spreading of the crustal plateau. Crust on Venus is produced by gradual vertical differentiation with little recycling rather than by the rapid horizontal creation and consumption characteristic of terrestrial sea-floor spreading.

Hot-spot evolution and the global tectonics of venus.

PubMed

Phillips, R J; Grimm, R E; Malin, M C

1991-05-03

The global tectonics of Venus may be dominated by plumes rising from the mantle and impinging on the lithosphere, giving rise to hot spots. Global sea-floor spreading does not take place, but direct convective coupling of mantle flow fields to the lithosphere leads to regional-scale deformation and may allow lithospheric transport on a limited scale. A hot-spot evolutionary sequence comprises (i) a broad domal uplift resulting from a rising mantle plume, (ii) massive partial melting in the plume head and generation of a thickened crust or crustal plateau, (iii) collapse of dynamic topography, and (iv) creep spreading of the crustal plateau. Crust on Venus is produced by gradual vertical differentiation with little recycling rather than by the rapid horizontal creation and consumption characteristic of terrestrial sea-floor spreading.

The role of hot spot mix in the low-foot and high-foot implosions on the NIF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, T.; Patel, P. K.; Izumi, N.

Hydrodynamic mix of the ablator into the DT fuel layer and hot spot can be a critical performance limitation in inertial confinement fusion implosions. This mix results in increased radiation loss, cooling of the hot spot, and reduced neutron yield. To quantify the level of mix, we have developed a simple model that infers the level of contamination using the ratio of the measured x-ray emission to the neutron yield. The principal source for the performance limitation of the “low-foot” class of implosions appears to have been mix. As a result, lower convergence “high-foot” implosions are found to be lessmore » susceptible to mix, allowing velocities of >380 km/s to be achieved.« less

The role of hot spot mix in the low-foot and high-foot implosions on the NIF

DOE PAGES

Ma, T.; Patel, P. K.; Izumi, N.; ...

2017-05-18

Hydrodynamic mix of the ablator into the DT fuel layer and hot spot can be a critical performance limitation in inertial confinement fusion implosions. This mix results in increased radiation loss, cooling of the hot spot, and reduced neutron yield. To quantify the level of mix, we have developed a simple model that infers the level of contamination using the ratio of the measured x-ray emission to the neutron yield. The principal source for the performance limitation of the “low-foot” class of implosions appears to have been mix. As a result, lower convergence “high-foot” implosions are found to be lessmore » susceptible to mix, allowing velocities of >380 km/s to be achieved.« less

Community Rates of Breastfeeding Initiation.

PubMed

Grubesic, Tony H; Durbin, Kelly M

2016-11-01

Breastfeeding initiation rates vary considerably across racial and ethnic groups, maternal age, and education level, yet there are limited data concerning the influence of geography on community rates of breastfeeding initiation. This study aimed to describe how community rates of breastfeeding initiation vary in geographic space, highlighting "hot spots" and "cool spots" of initiation and exploring the potential connections between race, socioeconomic status, and urbanization levels on these patterns. Birth certificate data from the Kentucky Department of Health for 2004-2010 were combined with county-level geographic base files, Census 2010 demographic and socioeconomic data, and Rural-Urban Continuum Codes to conduct a spatial statistical analysis of community rates of breastfeeding initiation. Between 2004 and 2010, the average rate of breastfeeding initiation for Kentucky increased from 43.84% to 49.22%. Simultaneously, the number of counties identified as breastfeeding initiation hot spots also increased, displaying a systematic geographic pattern in doing so. Cool spots of breastfeeding initiation persisted in rural, Appalachian Kentucky. Spatial regression results suggested that unemployment, income, race, education, location, and the availability of International Board Certified Lactation Consultants are connected to breastfeeding initiation. Not only do spatial analytics facilitate the identification of breastfeeding initiation hot spots and cool spots, but they can be used to better understand the landscape of breastfeeding initiation and help target breastfeeding education and/or support efforts.

There is no bidirectional hot-spot in Sentinel-2 data

NASA Astrophysics Data System (ADS)

Li, Z.; Roy, D. P.; Zhang, H.

2017-12-01

The Sentinel-2 multi-spectral instrument (MSI) acquires reflective wavelength observations with directional effects due to surface reflectance anisotropy, often described by the bidirectional reflectance distribution function (BRDF). Recently, we quantified Sentinel-2A (S2A) BRDF effects for 20° × 10° of southern Africa sensed in January and in April 2016 and found maximum BRDF effects for the January data and at the western scan edge, i.e., in the back-scatter direction (Roy et al. 2017). The hot-spot is the term used to describe the increased directional reflectance that occurs over most surfaces when the solar and viewing directions coincide, and has been observed in wide-field of view data such as MODIS. Recently, we observed that Landsat data will not have a hot-spot because the global annual minimum solar zenith angle is more than twice the maximum view zenith angle (Zhang et al. 2016). This presentation examines if there is a S2A hot-spot which may be possible as it has a wider field of view (20.6°) and higher orbit (786 km) than Landsat. We examined a global year of S2A metadata extracted using the Committee on Earth Observation Satellite Visualization Environment (COVE) tool, computed the solar zenith angles in the acquisition corners, and ranked the acquisitions by the solar zenith angle in the back-scatter direction. The available image data for the 10 acquisitions with the smallest solar zenith angle over the year were ordered from the ESA and their geometries examined in detail. The acquisition closest to the hot-spot had a maximum scattering angle of 173.61° on its western edge (view zenith angle 11.91°, solar zenith angle 17.97°) and was acquired over 60.80°W 24.37°N on June 2nd 2016. Given that hot-spots are only apparent when the scattering angle is close to 180° we conclude from this global annual analysis that there is no hot-spot in Sentinel-2 data. Roy, D.P, Li, J., Zhang, H.K., Yan, L., Huang, H., Li, Z., 2017, Examination of Sentinel-2A multi-spectral instrument (MSI) reflectance anisotropy and the suitability of a general method to normalize MSI reflectance to nadir BRDF adjusted reflectance, RSE. 199, 25-38. Zhang, H. K., Roy, D.P., Kovalskyy, V., 2016, Optimal solar geometry definition for global long term Landsat time series bi-directional reflectance normalization, IEEE TGRS. 54(3), 1410-1418.

Quantum and Classical Plasmonic Phenomena in Nanoparticle Arrays

NASA Astrophysics Data System (ADS)

Govorov, Alexander; Besteiro, Lucas; Khosravi Khorashad, Larousse; Kong, Xiang-Tian; Roller, Eva-Maria; Liedl, Tim

Using both classical and quantum approaches, we model plasmonic phenomena in nanoparticle (NP) dimers and trimers. Using a model of three nanoparticles, we propose a mechanism of non-dissipative and ultrafast plasmon passage assisted by hot spots. For this, the NP trimer should include two Au-NPs and one Ag-NP. In the Au-Ag-Au trimer, the two Au-plasmons become coupled via the virtual plasmon of the Ag-NP. The efficient and ultra-fast passage of the Au-plasmons assisted by the virtual Ag-plasmon only becomes possible when the inter-NP gaps in the trimer are small. In this coupling regime, the inter-NP gap regions become plasmonic hot spots that greatly enhance the plasmonic passage effect. At this moment, the plasmonic passage phenomenon was already observed experimentally using optical spectroscopy and the DNA-origami NP complexes. Other systems of our interest were a NP dimer and a nanostar with plasmonic hot spots. For those systems, we predict strong enhancement of the generation of energetic (hot) carriers.

The Median Isn't the Message: Elucidating Nutrient Hot spots and Hot Moments in a Sierra Nevada Forest Soil

NASA Astrophysics Data System (ADS)

Barnes, M. E.; Hart, S. C.; Johnson, D. W.; Meadows, M. W.

2015-12-01

Most biogeochemical studies in forests have concentrated on nutrient pools and transformations occurring at relatively large spatial scales (i.e., stand or small catchment), over monthly or annual time scales. Many of these studies have also focused on the average or medial values observed across the spatial or temporal scale studied, discounting outliers. However, extremely high values found consistently (hot spot) or infrequently (hot moment) at a given soil microsite may be critical for nutrient acquisition by organisms and nutrient retention by terrestrial ecosystems. We have been evaluating soil nutrient hot-spot and hot-moment phenomena vertically (to a 60-cm depth) and horizontally (2-m sampling interval within a 6 m x 6 m grid) in two areas within a mixed-conifer, Sierran forest experiencing a Mediterranean-type climate. Nutrient fluxes in space and time were measured using ion exchange resin capsules placed at various depths and collected at two times (first significant precipitation in fall and post-snowmelt in spring) per year. Our previous work over a single year showed that fluxes of Ca2+ and Mg2+ in mineral soil were substantially greater in the spring than in the fall, suggesting that soil water was a major factor in controlling these nutrient fluxes. The opposite pattern was found for NH4+ and Na+, where greater fluxes occurred following the first precipitation event in fall. Here, we report new data over two additional years at these same sites. Over the entire 3-year study, nutrient fluxes were greater in the fall for all mineral soil nutrients except Ca2+ and Mg2+. Calcium fluxes were consistent with previous results; however, Mg2+ demonstrated no statistical significance between fall and spring sampling dates. Generally, the number of high statistical outliers persisted through time for Ca2+ and Mg2+, suggesting hot spots for these nutrients. In contrast, large seasonal and annual changes in the number of high statistical outliers occurred for NH4+, NO3-, and PO43-, nutrients whose availabilities are more mediated by microbial activity than base cations. Further elucidation of the mechanisms responsible for nutrient hot spot-hot moment phenomena within soil should be invaluable for improving the predictive capacity of biogeochemical models and for scaling these models across space and time.

The evolution of the temperature field during cavity collapse in liquid nitromethane. Part I: inert case

NASA Astrophysics Data System (ADS)

Michael, L.; Nikiforakis, N.

2018-02-01

This work is concerned with the effect of cavity collapse in non-ideal explosives as a means of controlling their sensitivity. The main objective is to understand the origin of localised temperature peaks (hot spots) which play a leading order role at the early stages of ignition. To this end, we perform two- and three-dimensional numerical simulations of shock-induced single gas-cavity collapse in liquid nitromethane. Ignition is the result of a complex interplay between fluid dynamics and exothermic chemical reaction. In order to understand the relative contribution between these two processes, we consider in this first part of the work the evolution of the physical system in the absence of chemical reactions. We employ a multi-phase mathematical formulation which can account for the large density difference across the gas-liquid material interface without generating spurious temperature peaks. The mathematical and physical models are validated against experimental, analytic, and numerical data. Previous inert studies have identified the impact of the upwind (relative to the direction of the incident shock wave) side of the cavity wall to the downwind one as the main reason for the generation of a hot spot outside of the cavity, something which is also observed in this work. However, it is also apparent that the topology of the temperature field is more complex than previously thought and additional hot spot locations exist, which arise from the generation of Mach stems rather than jet impact. To explain the generation mechanisms and topology of the hot spots, we carefully follow the complex wave patterns generated in the collapse process and identify specifically the temperature elevation or reduction generated by each wave. This enables tracking each hot spot back to its origins. It is shown that the highest hot spot temperatures can be more than twice the post-incident shock temperature of the neat material and can thus lead to ignition. By comparing two-dimensional and three-dimensional simulation results in the context of the maximum temperature observed in the domain, it is apparent that three-dimensional calculations are necessary in order to avoid belated ignition times in reactive scenarios.

Global plate motion frames: Toward a unified model

NASA Astrophysics Data System (ADS)

Torsvik, Trond H.; Müller, R. Dietmar; van der Voo, Rob; Steinberger, Bernhard; Gaina, Carmen

2008-09-01

Plate tectonics constitutes our primary framework for understanding how the Earth works over geological timescales. High-resolution mapping of relative plate motions based on marine geophysical data has followed the discovery of geomagnetic reversals, mid-ocean ridges, transform faults, and seafloor spreading, cementing the plate tectonic paradigm. However, so-called "absolute plate motions," describing how the fragments of the outer shell of the Earth have moved relative to a reference system such as the Earth's mantle, are still poorly understood. Accurate absolute plate motion models are essential surface boundary conditions for mantle convection models as well as for understanding past ocean circulation and climate as continent-ocean distributions change with time. A fundamental problem with deciphering absolute plate motions is that the Earth's rotation axis and the averaged magnetic dipole axis are not necessarily fixed to the mantle reference system. Absolute plate motion models based on volcanic hot spot tracks are largely confined to the last 130 Ma and ideally would require knowledge about the motions within the convecting mantle. In contrast, models based on paleomagnetic data reflect plate motion relative to the magnetic dipole axis for most of Earth's history but cannot provide paleolongitudes because of the axial symmetry of the Earth's magnetic dipole field. We analyze four different reference frames (paleomagnetic, African fixed hot spot, African moving hot spot, and global moving hot spot), discuss their uncertainties, and develop a unifying approach for connecting a hot spot track system and a paleomagnetic absolute plate reference system into a "hybrid" model for the time period from the assembly of Pangea (˜320 Ma) to the present. For the last 100 Ma we use a moving hot spot reference frame that takes mantle convection into account, and we connect this to a pre-100 Ma global paleomagnetic frame adjusted 5° in longitude to smooth the reference frame transition. Using plate driving force arguments and the mapping of reconstructed large igneous provinces to core-mantle boundary topography, we argue that continental paleolongitudes can be constrained with reasonable confidence.

Anisotropic tomography of the Atlantic ocean

NASA Astrophysics Data System (ADS)

Silveira, G.; Stutzmann, E.

2003-04-01

We present a regional tri-dimensional model of the Atlantic Ocean with anisotropy. The model, derived from Rayleigh and Love phase velocity measurements, is defined from the Moho down to 300 km depth with a lateral resolution of about 500 km and is presented in terms of average isotropic S-wave velocity, azimuthal anisotropy and transverse isotropy. The cratons beneath North America, Brazil and Africa are clearly associated with fast S-wave velocity anomalies. The Mid Atlantic Ridge is a shallow structure in the North Atlantic corresponding to a negative velocity anomaly down to about 150 km depth. In contrast, the ridge negative signature is visible in the South Atlantic down to the deepest depth inverted, that is 300~km depth. This difference is probably related to the presence of hot-spots along or close to the ridge axis in the South Atlantic and may indicate a different mechanism for the ridge between the North and South Atlantic. Negative velocity anomalies are clearly associated with hot-spots from the surface down to at least 300km depth, they are much broader that the supposed size of the hot-spots and seem to be connected along a North-South direction. Down to 100 km depth, a fast S-wave velocity anomaly is extenting from Africa into the Atlantic Ocean within the zone defined as the Africa superswell area. This result indicates that the hot material rising from below does not reach the surface in this area but may be pushing the lithosphere upward. In most parts of the Atlantic, the azimuthal anisotropy directions remain stable with increasing depth. Close to the ridge, the fast S-wave velocity direction is roughly parallel to the sea floor spreading direction. The hot-spot anisotropy signature is striking beneath Bermuda, Cape Verde and Fernando Noronha islands where the fast S-wave velocity direction seems to diverge radially from the hot-spots. The Atlantic average radial anisotropy is similar to that of the PREM model, that is positive down to about 220 km, but with slightly smaller amplitude and null deeper. Cratons have a lower than average radial anisotropy. As for the velocities, there is a difference between North and South Atlantic. Most hot-spots and the South Atlantic ridge are associated with positive radial anisotropy perturbation whereas the North atlantic ridge corresponds to negative radial anisotropy perturbation.

Volcanic activity of Io observed in December 2001 with the Keck AO system: 2-5μ m sunlit and eclipse observations

NASA Astrophysics Data System (ADS)

Marchis, F.; de Pater, I.; Le Mignant, D.; Roe, H.; Fusco, T.; Graham, J. R.; Prange, R.; Macintosh, B.; Keck Science Team

2002-09-01

Volcanically active Io remains a mysterious and intriguing moon, despite numerous spacecraft flybys. Groundbased monitoring programs help characterize the time evolution of Io's volcanic activity, such as the frequency, spatial distribution and temperature of hot spots and outbursts. The satellite was observed intensively in December 2001 with the Keck II Adaptive Optics (AO) system and its recently installed near-infrared camera NIRC2. The spatial resolution after applying the MISTRAL myopic deconvolution method (130 km in K band and 200 km in L band) is better than that of the global images from the Galileo/NIMS instrument. A movie produced from 12 pictures taken every 30o in Ionian longitude provides a complete survey of Io's surface during one full rotation. A total of 26 active hot spots were detected in L band (3.8μ m), and approximatively three times more in M band (4.7μ m). One active hot spot is seen in K band (2.2μ m) in the Pele area. While Io is in Jupiter's shadow, it is invisible to the wavefront sensor, but its hot spots are easily visible in the near-infrared. We imaged Io during the 18 Dec. 2001 eclipse using Ganymede (30" from Io, moving relative to Io at 0.5"/min) as a reference source. Although isoplanatic effects limited AO performance, numerous spots are detected at both K' and L'. We will show the results of detailed studies (temperature, emission area, nature) for several of the hot spots. Keck Science team is composed of S. Kwok, P. Amico, R. Campbell, F. Chaffee, A. Conrad, A. Contos, B. Goodrich, G. Hill, D. Sprayberry, P. Stomski, P. Wizinowich (W.M. Keck Observatory). This work has been supported in part by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783.

Effects of the P2 M-band flux asymmetry of laser-driven gold Hohlraums on the implosion of ICF ignition capsule

NASA Astrophysics Data System (ADS)

Li, Yongsheng; Gu, Jianfa; Wu, Changshu; Song, Peng; Dai, Zhensheng; Li, Shuanggui; Li, Xin; Kang, Dongguo; Gu, Peijun; Zheng, Wudi; Zou, Shiyang; Ding, Yongkun; Lan, Ke; Ye, Wenhua; Zhang, Weiyan

2016-07-01

Low-mode asymmetries in the laser-indirect-drive inertial confinement fusion implosion experiments conducted on the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] are deemed the main obstacles hindering further improvement of the nuclear performance of deuterium-tritium-layered capsules. The dominant seeds of these asymmetries include the P2 and P4 asymmetries of x-ray drives and P2 asymmetry introduced by the supporting "tent." Here, we explore the effects of another possible seed that can lead to low-mode asymmetric implosions, i.e., the M-band flux asymmetry (MFA) in laser-driven cylindrical gold Hohlraums. It is shown that the M-band flux facilitates the ablation and acceleration of the shell, and that positive P2 MFAs can result in negative P2 asymmetries of hot spots and positive P2 asymmetries of shell's ρR. An oblate or toroidal hot spot, depending on the P2 amplitude of MFA, forms at stagnation. The energy loss of such a hot spot via electron thermal conduction is seriously aggravated not only due to the enlarged hot spot surface but also due to the vortices that develop and help transferring thermal energy from the hotter center to the colder margin of such a hot spot. The cliffs of nuclear performance for the two methodologies of applying MFA (i.e., symmetric flux in the presence of MFA and MFA added for symmetric soft x-ray flux) are obtained locating at 9.5% and 5.0% of P2/P0 amplitudes, respectively.

Geodynamic implications for zonal and meridional isotopic patterns across the northern Lau and North Fiji Basins

NASA Astrophysics Data System (ADS)

Price, Allison A.; Jackson, Matthew G.; Blichert-Toft, Janne; Kurz, Mark D.; Gill, Jim; Blusztajn, Jerzy; Jenner, Frances; Brens, Raul; Arculus, Richard

2017-03-01

We present new Sr-Nd-Pb-Hf-He isotopic data for 65 volcanic samples from the northern Lau and North Fiji Basins. This includes 47 lavas obtained from 40 dredge sites spanning an east-west transect across the Lau and North Fiji basins, 10 ocean island basalt (OIB)-type lavas collected from seven Fijian islands, and eight OIB lavas sampled on Rotuma. For the first time, we are able to map clear north-south and east-west geochemical gradients in 87Sr/86Sr across the northern Lau and North Fiji Basins: lavas with the most geochemically enriched radiogenic isotopic signatures are located in the northeast Lau Basin, while signatures of geochemical enrichment are diminished to the south and west away from the Samoan hot spot. Based on these geochemical patterns and plate reconstructions of the region, these observations are best explained by the addition of Samoa, Rurutu, and Rarotonga hot spot material over the past 4 Ma. We suggest that underplated Samoan material has been advected into the Lau Basin over the past ˜4 Ma. As the slab migrated west (and toward the Samoan plume) via rollback over time, younger and hotter (and therefore less viscous) underplated Samoan plume material was entrained. Thus, entrainment efficiency of underplated plume material was enhanced, and Samoan plume signatures in the Lau Basin became stronger as the trench approached the Samoan hot spot. The addition of subducted volcanoes from the Cook-Austral Volcanic Lineament first from the Rarotonga hot spot, then followed by the Rurutu hot spot, contributes to the extreme geochemical signatures observed in the northeast Lau Basin.

To Treat or to Prevent?

PubMed Central

Cerdá, Magdalena; Tracy, Melissa; Keyes, Katherine M.; Galea, Sandro

2015-01-01

Background Violence-related post-traumatic stress disorder (PTSD) remains a prevalent and disabling psychiatric disorder in urban areas. However, the most effective allocation of resources into prevention and treatment to reduce this problem is unknown. We contrasted the impact of two interventions on violence-related PTSD: (1) a population-level intervention intended to prevent violence (i.e., hot-spot policing), and (2) an individual-level intervention intended to shorten PTSD duration (i.e., cognitive-behavioral therapy—CBT). Methods We used agent-based modeling to simulate violence and PTSD in New York City under four scenarios: (1) no intervention, (2) targeted policing to hot spots of violence, (3) increased access to CBT for people who suffered from violence-related PTSD, and (4) a combination of the two interventions. Results Combined prevention and treatment produced the largest decrease in violence-related PTSD prevalence: hot-spot policing plus a 50% increase in CBT for 5 years reduced the annual prevalence of violence-related PTSD from 3.6% (95% confidence interval = 3.5%, 3.6%) to 3.4% (3.3%, 3.5%). It would have been necessary to implement hot-spot policing or to increase CBT by 200% for 10 years for either intervention to achieve the same reduction in isolation. Conclusions This study provides an empirically informed demonstration that investment in combined strategies that target social determinants of mental illness and provide evidence-based treatment to those affected by psychiatric disorders can produce larger reductions in the population burden from violence-related PTSD than either preventive or treatment interventions alone. However, neither hot-spot policing nor CBT, alone or combined, will produce large shifts in the population prevalence of violence-related PTSD. PMID:26237744

To Treat or to Prevent?: Reducing the Population Burden of Violence-related Post-traumatic Stress Disorder.

PubMed

Cerdá, Magdalena; Tracy, Melissa; Keyes, Katherine M; Galea, Sandro

2015-09-01

Violence-related post-traumatic stress disorder (PTSD) remains a prevalent and disabling psychiatric disorder in urban areas. However, the most effective allocation of resources into prevention and treatment to reduce this problem is unknown. We contrasted the impact of two interventions on violence-related PTSD: (1) a population-level intervention intended to prevent violence (i.e., hot-spot policing), and (2) an individual-level intervention intended to shorten PTSD duration (i.e., cognitive-behavioral therapy-CBT). We used agent-based modeling to simulate violence and PTSD in New York City under four scenarios: (1) no intervention, (2) targeted policing to hot spots of violence, (3) increased access to CBT for people who suffered from violence-related PTSD, and (4) a combination of the two interventions. Combined prevention and treatment produced the largest decrease in violence-related PTSD prevalence: hot-spot policing plus a 50% increase in CBT for 5 years reduced the annual prevalence of violence-related PTSD from 3.6% (95% confidence interval = 3.5%, 3.6%) to 3.4% (3.3%, 3.5%). It would have been necessary to implement hot-spot policing or to increase CBT by 200% for 10 years for either intervention to achieve the same reduction in isolation. This study provides an empirically informed demonstration that investment in combined strategies that target social determinants of mental illness and provide evidence-based treatment to those affected by psychiatric disorders can produce larger reductions in the population burden from violence-related PTSD than either preventive or treatment interventions alone. However, neither hot-spot policing nor CBT, alone or combined, will produce large shifts in the population prevalence of violence-related PTSD.

Shock Initiation of Explosives - High Temperature Hot Spots Explained

NASA Astrophysics Data System (ADS)

Bassett, Will

2017-06-01

The pore-collapse mechanism for hot spot creation is currently one of the most intensely studied subjects in the initiation of energetic materials. In the present study, we use 1.5 - 3.5 km s-1 laser-driven flyer plates to impact microgram charges of both polymer-bound and pure pentaerythritol tetranitrate (PETN) while recording the temperature and spatially-averaged emissivity with a high-speed optical pyrometer. The 32-color pyrometer has nanosecond time resolution and a high dynamic range with sensitivity to temperatures from 7000 to 2000 K. Hot spot temperatures of 4000 K at impact are observed in the polymer-bound explosive charges where an elastomeric binder is used to fill void spaces. In pure PETN and more heterogeneous polymer-bound charges, in which significant void space is present, hot spot temperatures of 6000 K are observed, similar to previous reports with significant porosity. We attribute these high temperatures to gas-phase products formed in-situ being compressed under the driving shock. Experiments performed under various gas environments (air, butane, etc.) showed a strong influence on observed temperature upon impact. Control experiments where the PETN in the polymer-bound charges were replaced with sucrose and silica reinforce the result that hot spots are a result of in-situ gas formation from decomposition of organic molecules. US Air Force Office of Scientific Research awards FA9550-14-1-0142 and FA9550-16-1-0042; US Army Research Office award W911NF-13-1-0217; Defense Threat Reduction Agency award HDTRA1-12-1-0011. In collaboration with: Belinda Pacheco and Dana Dlott, University of Illinois at Urbana Champaign.

Effects of the P2 M-band flux asymmetry of laser-driven gold Hohlraums on the implosion of ICF ignition capsule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yongsheng; Graduate School, China Academy of Engineering Physics, Beijing 100088; Gu, Jianfa

Low-mode asymmetries in the laser-indirect-drive inertial confinement fusion implosion experiments conducted on the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] are deemed the main obstacles hindering further improvement of the nuclear performance of deuterium-tritium-layered capsules. The dominant seeds of these asymmetries include the P2 and P4 asymmetries of x-ray drives and P2 asymmetry introduced by the supporting “tent.” Here, we explore the effects of another possible seed that can lead to low-mode asymmetric implosions, i.e., the M-band flux asymmetry (MFA) in laser-driven cylindrical gold Hohlraums. It is shown that the M-band flux facilitates themore » ablation and acceleration of the shell, and that positive P2 MFAs can result in negative P2 asymmetries of hot spots and positive P2 asymmetries of shell's ρR. An oblate or toroidal hot spot, depending on the P2 amplitude of MFA, forms at stagnation. The energy loss of such a hot spot via electron thermal conduction is seriously aggravated not only due to the enlarged hot spot surface but also due to the vortices that develop and help transferring thermal energy from the hotter center to the colder margin of such a hot spot. The cliffs of nuclear performance for the two methodologies of applying MFA (i.e., symmetric flux in the presence of MFA and MFA added for symmetric soft x-ray flux) are obtained locating at 9.5% and 5.0% of P2/P0 amplitudes, respectively.« less

Comparison of the methods for measuring the Ki-67 labeling index in adrenocortical carcinoma: manual versus digital image analysis.

PubMed

Yamazaki, Yuto; Nakamura, Yasuhiro; Shibahara, Yukiko; Konosu-Fukaya, Sachiko; Sato, Naomi; Kubota-Nakayama, Fumie; Oki, Yutaka; Baba, Satoshi; Midorikawa, Sanae; Morimoto, Ryo; Satoh, Fumitoshi; Sasano, Hironobu

2016-07-01

Adrenocortical carcinoma (ACC) is a rare, highly malignant neoplasm harboring marked histologic heterogeneity. The Ki-67 labeling index (LI) is one of the most effective diagnostic and prognostic markers in ACC. However, its assessment has by no means been standardized. Therefore, in this study, we analyzed the Ki-67 LI in 18 ACC cases both by seven pathologists using microscopes (MA; manual analysis) and with digital image analysis (DIA) and also compared the Ki-67 LI obtained by selecting "hot spots" and formulating the "average" reading of the whole tumor specimen. In addition, we performed statistical analysis of the association between Ki-67 LI and the clinical and pathologic features of individual cases. The DIA was significantly correlated with MA in hot spots but not in the average fields. The Ki-67 LI in hot spots was significantly and consistently higher than that in average areas by both MA and DIA, indicating intratumoral heterogeneity. The Ki-67 LI was significantly correlated with the Weiss criteria (eosinophilic cytoplasm, nuclear atypia, atypical mitoses, and sinusoidal invasion) by any mode of evaluation. The clinical outcome was significantly better in the patients with a Ki-67 < 10% than in those with a Ki-67 > 10% by MA in hot spots. The Ki-67 LI in hot spots measured by MA best reflected the clinical and pathologic features of ACC. Employment of DIA to obtain the Ki-67 LI in ACC requires further improvement, including correction of its overestimation of the value by counting non-tumorous cells and nuclear segmentation in areas of high cell density. Copyright © 2016 Elsevier Inc. All rights reserved.

Noise of high-performance aircraft at afterburner

NASA Astrophysics Data System (ADS)

Tam, Christopher K. W.; Parrish, Sarah A.

2015-09-01

The noise from a high-performance aircraft at afterburner is investigated. The main objective is to determine whether the dominant noise components are the same or similar to those of a hot supersonic laboratory jet. For this purpose, measured noise data from F-22A Raptors are analyzed. It is found, based on both spectral and directivity data, that there is a new dominant noise component in addition to the usual turbulent mixing noise. The characteristic features of the new noise component are identified. Measured data indicates that the new noise component is observed only when the rate of fuel burn of the engine is increased significantly above that of the intermediate power setting. This suggests that the new noise component is combustion related. The possibility that it is indirect combustion noise generated by the passage of hot spots from the afterburner through the nozzle of the jet is investigated. Because flow and temperature data were not measured in the F-22A engine tests, to provide support to the proposition, numerical simulations of indirect combustion noise generation due to the passing of an entropy wave pulse (a hot spot) through a military-style nozzle are carried out. Sound generation is observed at the front and at the back of the pulse. This creates a fast and a slow acoustic wave as the sound radiates out from the nozzle exit. Quantitative estimates of the principal directions of acoustic radiation due to the emitted fast and slow acoustic waves are made. It is found that there are reasonably good agreements with measured data. To estimate the intensity level (IL) of the radiated indirect combustion noise, a time-periodic entropy wave train of 15 percent temperature fluctuation is used as a model of the hot spots coming out of the afterburner. This yields an IL of 175.5 dB. This is a fairly intense noise source, well capable of causing the radiation of the new jet noise component.

WE-D-BRA-04: Online 3D EPID-Based Dose Verification for Optimum Patient Safety

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spreeuw, H; Rozendaal, R; Olaciregui-Ruiz, I

2015-06-15

Purpose: To develop an online 3D dose verification tool based on EPID transit dosimetry to ensure optimum patient safety in radiotherapy treatments. Methods: A new software package was developed which processes EPID portal images online using a back-projection algorithm for the 3D dose reconstruction. The package processes portal images faster than the acquisition rate of the portal imager (∼ 2.5 fps). After a portal image is acquired, the software seeks for “hot spots” in the reconstructed 3D dose distribution. A hot spot is in this study defined as a 4 cm{sup 3} cube where the average cumulative reconstructed dose exceedsmore » the average total planned dose by at least 20% and 50 cGy. If a hot spot is detected, an alert is generated resulting in a linac halt. The software has been tested by irradiating an Alderson phantom after introducing various types of serious delivery errors. Results: In our first experiment the Alderson phantom was irradiated with two arcs from a 6 MV VMAT H&N treatment having a large leaf position error or a large monitor unit error. For both arcs and both errors the linac was halted before dose delivery was completed. When no error was introduced, the linac was not halted. The complete processing of a single portal frame, including hot spot detection, takes about 220 ms on a dual hexacore Intel Xeon 25 X5650 CPU at 2.66 GHz. Conclusion: A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for various kinds of gross delivery errors. The detection of hot spots was proven to be effective for the timely detection of these errors. Current work is focused on hot spot detection criteria for various treatment sites and the introduction of a clinical pilot program with online verification of hypo-fractionated (lung) treatments.« less

Using absolute x-ray spectral measurements to infer stagnation conditions in ICF implosions

NASA Astrophysics Data System (ADS)

Patel, Pravesh; Benedetti, L. R.; Cerjan, C.; Clark, D. S.; Hurricane, O. A.; Izumi, N.; Jarrott, L. C.; Khan, S.; Kritcher, A. L.; Ma, T.; Macphee, A. G.; Landen, O.; Spears, B. K.; Springer, P. T.

2016-10-01

Measurements of the continuum x-ray spectrum emitted from the hot-spot of an ICF implosion can be used to infer a number thermodynamic properties at stagnation including temperature, pressure, and hot-spot mix. In deuterium-tritium (DT) layered implosion experiments on the National Ignition Facility (NIF) we field a number of x-ray diagnostics that provide spatial, temporal, and spectrally-resolved measurements of the radiated x-ray emission. We report on analysis of these measurements using a 1-D hot-spot model to infer thermodynamic properties at stagnation. We compare these to similar properties that can be derived from DT fusion neutron measurements. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Chemistry Related to Possible Outgassing Sources on Mars

NASA Technical Reports Server (NTRS)

Wong, A. S.; Atreya, S. K.; Renno, N. O.

2003-01-01

An earlier paper, Chemical markers of possible hot spots on Mars by A. S. Wong, S. K. Atreya and Th. Encrenaz, explored the modification of the atmosphere of Mars following an influx of methane, sulfur dioxide and hydrogen sulfide (CH4, SO2, H2S) from any outgassing sources which are referred to as hot spots. The feasibility of detection of the new species by Planetary Fourier Spectrometer on Mars Express is reported in a subsequent paper, Atmospheric photochemistry above possible martian hot spots by A. S. Wong, S. K. Atreya, V. Formisano, Th. Encrenaz and N. Ignatiev. This abstract is a follow-up on the previous two papers. Here we treat the effect of any outgassed halogens rigorously. We also make estimates of dilution factors relative to the source location following convection and meridional transport.

Universal Scaling of Robust Thermal Hot Spot and Ionic Current Enhancement by Focused Ohmic Heating in a Conic Nanopore

NASA Astrophysics Data System (ADS)

Pan, Zehao; Wang, Ceming; Li, Meng; Chang, Hsueh-Chia

2016-09-01

A stable nanoscale thermal hot spot, with temperature approaching 100 °C , is shown to be sustained by localized Ohmic heating of a focused electric field at the tip of a slender conic nanopore. The self-similar (length-independent) conic geometry allows us to match the singular heat source at the tip to the singular radial heat loss from the slender cone to obtain a self-similar steady temperature profile along the cone and the resulting ionic current conductance enhancement due to viscosity reduction. The universal scaling, which depends only on a single dimensionless parameter Z , collapses the measured conductance data and computed temperature profiles in ion-track conic nanopores and conic nanopipettes. The collapsed numerical data reveal universal values for the hot-spot location and temperature in an aqueous electrolyte.

Universal Scaling of Robust Thermal Hot Spot and Ionic Current Enhancement by Focused Ohmic Heating in a Conic Nanopore.

PubMed

Pan, Zehao; Wang, Ceming; Li, Meng; Chang, Hsueh-Chia

2016-09-23

A stable nanoscale thermal hot spot, with temperature approaching 100 °C, is shown to be sustained by localized Ohmic heating of a focused electric field at the tip of a slender conic nanopore. The self-similar (length-independent) conic geometry allows us to match the singular heat source at the tip to the singular radial heat loss from the slender cone to obtain a self-similar steady temperature profile along the cone and the resulting ionic current conductance enhancement due to viscosity reduction. The universal scaling, which depends only on a single dimensionless parameter Z, collapses the measured conductance data and computed temperature profiles in ion-track conic nanopores and conic nanopipettes. The collapsed numerical data reveal universal values for the hot-spot location and temperature in an aqueous electrolyte.

Identifying fish diversity hot-spots in data-poor situations.

PubMed

Fonseca, Vinícius Prado; Pennino, Maria Grazia; de Nóbrega, Marcelo Francisco; Oliveira, Jorge Eduardo Lins; de Figueiredo Mendes, Liana

2017-08-01

One of the more challenging tasks in Marine Spatial Planning (MSP) is identifying critical areas for management and conservation of fish stocks. However, this objective is difficult to achieve in data-poor situations with different sources of uncertainty. In the present study we propose a combination of hierarchical Bayesian spatial models and remotely sensed estimates of environmental variables to be used as flexible and reliable statistical tools to identify and map fish species richness and abundance hot-spots. Results show higher species aggregates in areas with higher sea floor rugosity and habitat complexity, and identify clear richness hot-spots. Our findings identify sensitive habitats through essential and easy-to-use interpretation tools, such as predictive maps, which can contribute to improving management and operability of the studied data-poor situations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reproducible nucleation sites for flux dendrites in MgB 2

NASA Astrophysics Data System (ADS)

Johansen, T. H.; Shantsev, D. V.; Olsen, Å. A. F.; Roussel, M.; Pan, A. V.; Dou, S. X.

2007-12-01

Magneto-optical imaging was used to study dendritic flux penetration in films of MgB 2. By repeating experiments under the same external conditions, reproducible features were seen in the pattern formation; dendrites tend to nucleate from fixed locations along the edge. However, their detailed structure deeper inside the film is never reproduced. The reproducibility in nucleation sites is explained as a result of edge roughness causing field hot spots.

Beach Erosional Hot Spots: Types, Causes, and Solutions

DTIC Science & Technology

2001-09-01

Pope, and McClung (1999) showed that variable erosion rates along a beach nourishment project on Presque Isle , Pennsylvania (Lake Erie ) were related to...and McClung, J. K. (1999). “Coastal response to a detached breakwater system: Presque Isle , Erie , PA, U.S.A,” Proc. Coastal Sediments ’99, ASCE...borrow pits located too close to shore at Grand Isle , LA. The resultant cuspate shoreline was subsequently predicted by refraction analysis

CO oxidation studies over supported noble metal catalysts and single crystals: A review

NASA Technical Reports Server (NTRS)

Boecker, Dirk; Gonzalez, Richard D.

1987-01-01

The catalytic oxidation of CO over noble metal catalysts is reviewed. Results obtained on supported noble metal catalysts and single crystals both at high pressures and under UHV conditions are compared. The underlying causes which result in surface instabilities and multiple steady-state oscillations are considered, in particular, the occurrence of hot spots. CO islands of reactivity, surface oxide formation and phase transformations under oscillatory conditions are discussed.

Rationalizing Tight Ligand Binding through Cooperative Interaction Networks

PubMed Central

2011-01-01

Small modifications of the molecular structure of a ligand sometimes cause strong gains in binding affinity to a protein target, rendering a weakly active chemical series suddenly attractive for further optimization. Our goal in this study is to better rationalize and predict the occurrence of such interaction hot-spots in receptor binding sites. To this end, we introduce two new concepts into the computational description of molecular recognition. First, we take a broader view of noncovalent interactions and describe protein–ligand binding with a comprehensive set of favorable and unfavorable contact types, including for example halogen bonding and orthogonal multipolar interactions. Second, we go beyond the commonly used pairwise additive treatment of atomic interactions and use a small world network approach to describe how interactions are modulated by their environment. This approach allows us to capture local cooperativity effects and considerably improves the performance of a newly derived empirical scoring function, ScorpionScore. More importantly, however, we demonstrate how an intuitive visualization of key intermolecular interactions, interaction networks, and binding hot-spots supports the identification and rationalization of tight ligand binding. PMID:22087588

Hot-Spot Fatigue and Impact Damage Detection on a Helicopter Tailboom

DTIC Science & Technology

2011-09-01

other 14 PZT disks were used as sensors. Among the 28 PZT disks, 16 PZT disks were placed in the two fatigue hot-spot areas to detect cracks initiated...more efficient and effective airframe maintenance, fatigue cracking and impact damage detection technologies were developed and demonstrated on a...SHM system in successfully monitoring fatigue cracks initiated from cyclical loading conditions; detecting, locating and quantifying ballistic

Sensitivity Characterization of Pressed Energetic Materials using Flyer Plate Mesoscale Simulations

NASA Astrophysics Data System (ADS)

Rai, Nirmal; Udaykumar, H. S.

Heterogeneous energetic materials like pressed explosives have complicated microstructure and contain various forms of heterogeneities such as pores, micro-cracks, energetic crystals etc. It is widely accepted that the presence of these heterogeneities can affect the sensitivity of these materials under shock load. The interaction of shock load with the microstructural heterogeneities may leads to the formation of local heated regions known as ``hot spots''. Chemical reaction may trigger at the hot spot regions depending on the hot spot temperature and the duration over which the temperature can be maintained before phenomenon like heat conduction, rarefaction waves withdraws energy from it. There are different mechanisms which can lead to the formation of hot spots including void collapse. The current work is focused towards the sensitivity characterization of two HMX based pressed energetic materials using flyer plate mesoscale simulations. The aim of the current work is to develop mesoscale numerical framework which can perform simulations by replicating the laboratory based flyer plate experiments. The current numerical framework uses an image processing approach to represent the microstructural heterogeneities incorporated in a massively parallel Eulerian code SCIMITAR3D. The chemical decomposition of HMX is modeled using Henson-Smilowitz reaction mechanism. The sensitivity characterization is aimed towards obtaining James initiation threshold curve and comparing it with the experimental results.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Ya-Wen; Dutrey, Anne; Guilloteau, Stéphane

We aim to unveil the observational imprint of physical mechanisms that govern planetary formation in the young, multiple system GG Tau A. We present ALMA observations of {sup 12}CO and {sup 13}CO 3–2 and 0.9 mm continuum emission with 0.″35 resolution. The {sup 12}CO 3–2 emission, found within the cavity of the circumternary dust ring (at radius <180 au) where no {sup 13}CO emission is detected, confirms the presence of CO gas near the circumstellar disk of GG Tau Aa. The outer disk and the recently detected hot spot lying at the outer edge of the dust ring are mappedmore » both in {sup 12}CO and {sup 13}CO. The gas emission in the outer disk can be radially decomposed as a series of slightly overlapping Gaussian rings, suggesting the presence of unresolved gaps or dips. The dip closest to the disk center lies at a radius very close to the hot spot location at ∼250–260 au. The CO excitation conditions indicate that the outer disk remains in the shadow of the ring. The hot spot probably results from local heating processes. The two latter points reinforce the hypothesis that the hot spot is created by an embedded proto-planet shepherding the outer disk.« less

Hot-spot analysis for drug discovery targeting protein-protein interactions.

PubMed

Rosell, Mireia; Fernández-Recio, Juan

2018-04-01

Protein-protein interactions are important for biological processes and pathological situations, and are attractive targets for drug discovery. However, rational drug design targeting protein-protein interactions is still highly challenging. Hot-spot residues are seen as the best option to target such interactions, but their identification requires detailed structural and energetic characterization, which is only available for a tiny fraction of protein interactions. Areas covered: In this review, the authors cover a variety of computational methods that have been reported for the energetic analysis of protein-protein interfaces in search of hot-spots, and the structural modeling of protein-protein complexes by docking. This can help to rationalize the discovery of small-molecule inhibitors of protein-protein interfaces of therapeutic interest. Computational analysis and docking can help to locate the interface, molecular dynamics can be used to find suitable cavities, and hot-spot predictions can focus the search for inhibitors of protein-protein interactions. Expert opinion: A major difficulty for applying rational drug design methods to protein-protein interactions is that in the majority of cases the complex structure is not available. Fortunately, computational docking can complement experimental data. An interesting aspect to explore in the future is the integration of these strategies for targeting PPIs with large-scale mutational analysis.

SERS Assay for Copper(II) Ions Based on Dual Hot-Spot Model Coupling with MarR Protein: New Cu2+-Specific Biorecognition Element.

PubMed

Wang, Yulong; Su, Zhenhe; Wang, Limin; Dong, Jinbo; Xue, Juanjuan; Yu, Jiao; Wang, Yuan; Hua, Xiude; Wang, Minghua; Zhang, Cunzheng; Liu, Fengquan

2017-06-20

We have developed a rapid and ultrasensitive surface-enhanced Raman scattering (SERS) assay for Cu 2+ detection using the multiple antibiotic resistance regulator (MarR) as specific bridging molecules in a SERS hot-spot model. In the assay, Cu 2+ induces formation of MarR tetramers, which provide Au nanoparticle (NP)-AuNP bridges, resulting in the formation of SERS hot spots. 4-Mercaptobenzoic acid (4-MBA) was used as a Raman reporter. The addition of Cu 2+ increased the Raman intensity of 4-MBA. Use of a dual hot-spot signal-amplification strategy based on AuNP-AgNP heterodimers combined through antigen-antibody reactions increased the sensitivity of the sensing platform by 50-fold. The proposed method gave a linear response for Cu 2+ detection in the range of 0.5-1000 nM, with a detection limit of 0.18 nM, which is 5 orders of magnitude lower than the U.S. Environmental Protection Agency limit for Cu 2+ in drinking water (20 μM). In addition, all analyses can be completed in less than 15 min. The high sensitivity, high specificity, and rapid detection capacity of the SERS assay therefore provide a combined advantage over current assays.

A Pulsating X-Ray Hot Spot on Jupiter

NASA Technical Reports Server (NTRS)

Gladstone, G. R.; Waite, J. H.; Grodent, D. C.; Crary, F. J.; Elsner, R. F.; Weisskopf, M. C.; Majeed, T.; Lewis, W. S.; Jahn, J.-M.; Bhardwaj, A.;

Wafer hotspot prevention using etch aware OPC correction

NASA Astrophysics Data System (ADS)

Hamouda, Ayman; Power, Dave; Salama, Mohamed; Chen, Ao

2016-03-01

As technology development advances into deep-sub-wavelength nodes, multiple patterning is becoming more essential to achieve the technology shrink requirements. Recently, Optical Proximity Correction (OPC) technology has proposed simultaneous correction of multiple mask-patterns to enable multiple patterning awareness during OPC correction. This is essential to prevent inter-layer hot-spots during the final pattern transfer. In state-of-art literature, multi-layer awareness is achieved using simultaneous resist-contour simulations to predict and correct for hot-spots during mask generation. However, this approach assumes a uniform etch shrink response for all patterns independent of their proximity, which isn't sufficient for the full prevention of inter-exposure hot-spot, for example different color space violations post etch or via coverage/enclosure post etch. In this paper, we explain the need to include the etch component during multiple patterning OPC. We also introduce a novel approach for Etch-aware simultaneous Multiple-patterning OPC, where we calibrate and verify a lumped model that includes the combined resist and etch responses. Adding this extra simulation condition during OPC is suitable for full chip processing from a computation intensity point of view. Also, using this model during OPC to predict and correct inter-exposures hot-spots is similar to previously proposed multiple-patterning OPC, yet our proposed approach more accurately corrects post-etch defects too.

Cryogenic tritium-hydrogen-deuterium and deuterium-tritium layer implosions with high density carbon ablators in near-vacuum hohlraums

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meezan, N. B., E-mail: meezan1@llnl.gov; Hopkins, L. F. Berzak; Pape, S. Le

2015-06-15

High Density Carbon (or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a deuterium-tritium (DT) layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a tritium-hydrogen-deuterium (THD) layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape.more » Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 × 10{sup 15} neutrons, 40% of the 1D simulated yield.« less

A quarter century of biomonitoring atmospheric pollution in the Czech Republic.

PubMed

Suchara, Ivan; Sucharová, Julie; Holá, Marie

2017-05-01

The Czech Republic (CZ) had extremely high emissions and atmospheric deposition of pollutants in the second half of the 1980s. Since the beginning of the 1990s, moss, spruce bark and forest floor humus have been used as bioindicators of air quality. In the first half of the 1990s, seven larger areas were found to be affected by high atmospheric deposition loads. Six of these "hot spots" were caused by industrial pollution sources, mainly situated in coal basins in the NW and NE part of the country, and one large area in the SE was affected by increased deposition loads of eroded soil particles. After restructuring of industry in CZ, these hot spots were substantially reduced or even disappeared between 1995 and 2000. Since 2000, only two larger areas with slightly increased levels of industrial pollutant deposition and a larger area affected by soil dust have repeatedly been identified by biomonitoring. The distribution of lead isotope ratios in moss showed the main deposition zones around important emission sources. Very high SO 2 emissions led to extreme acidity of spruce bark extracts (pH of about 2.3) at the end of the 1980s. The rate of increasing bark pH was strikingly similar to the rate of recovery of acid wet deposition measured at forest stations in CZ. By about 2005, when the median pH value in bark increased to about 3.2, the re-colonisation of trees by several epiphyte lichen species was observed throughout CZ. An increase in the accumulation of Chernobyl-derived 137 Cs in bark was detected at about ten sites affected by precipitation during the time when radioactive plumes crossed CZ (1986). Accumulated deposition loads in forest floor humus corresponded to the position of the moss and bark hot spots.

Absorptivity modulation on wavy molten steel surfaces: The influence of laser wavelength and angle of incidence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaplan, A. F. H.

The modulation of the angle-dependent Fresnel absorptivity across wavy molten steel surfaces during laser materials processing, like drilling, cutting, or welding, has been calculated. The absorptivity is strongly altered by the grazing angle of incidence of the laser beam on the processing front. Owing to its specific Brewster-peak characteristics, the 10.64 {mu}m wavelength CO{sub 2}-laser shows an opposite trend with respect to roughness and angle-of-incidence compared to lasers in the wavelength range of 532-1070 nm. Plateaus or rings of Brewster-peak absorptivity can lead to hot spots on a wavy surface, often in close proximity to cold spots caused by shadowmore » domains.« less

Answer to the dynamic (fretting effect) and static (oxide) behavior of electric contact surfaces: based on a five-year infrared thermographic study

NASA Astrophysics Data System (ADS)

Paez-Leon, Cristobal D.; Patino, Antonio R.; Aguillon, Luis

1991-03-01

This paper describes the results of a five-year study carried out in 38 power substations (230, 115, 34.5 and 13.8 Kv), located in the Western power electric system of CADAFE (Venezuela's national Electric Utility). A total of 154 hot spots were found between 1980 and 1982, a time span considered a reliable source of information in connection with methodology, term and results. The distribution of hot spots found during those years was 77, 33 and 44. The reduction of the spot/substation parameter was found to be 4.1, 3.3 and 3.1, respectively. Every item detected could have been the cause of major interruptions, locally and regionally, or even the system's blackout. The methodology used to determine the major concentration of findings and their location on the equipment, followed the sequence of Pareto's Diagram and Ishikawa's Graphic. Based on the results of the study whose results are presented here, a lubricant and compound-aid connector for Al-Al and bimetallic electric connections was formulated, developed, manufactured, tested (at IREQ laboratories) and traded (CONECTECH CAC- 01). To date, the whole process represents 12 years of work. The connector's behavior and reliability are being tested throughout Venezuela's national electric system (responsible for the supply of around 50,000 Gwh/year) with the use of 12 Tons of CONECTECH CAC-01.

A hot-spot-active magnetic graphene oxide substrate for microRNA detection based on cascaded chemiluminescence resonance energy transfer

NASA Astrophysics Data System (ADS)

Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying

2015-02-01

Herein, a cascaded chemiluminescence resonance energy transfer (C-CRET) process was demonstrated from horseradish peroxidase (HRP)-mimicking DNAzyme-catalyzed luminol-H2O2 to fluorescein and further to graphene oxide (GO) when HRP-mimicking DNAzyme/fluorescein was in close proximity to the GO surface. The proposed C-CRET system was successfully implemented to construct three modes of C-CRET hot-spot-active substrates (modes I, II and III) by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs (hot-spot-generation probes) on magnetic GO (MGO), resulting in a signal ``off'' state due to the quenching of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122 (miRNA-122), the targets (mode I) or the new triggers that were generated through a strand displacement reaction (SDR) initiated by miRNA-122 (modes II and III) hybridized with the loop domains of hairpin probes on MGO to form double-stranded (modes I and II) or triplex-stem structures (mode III), causing an ``open'' configuration of the hairpin probe and a CRET signal ``on'' state, thus achieving sensitive and selective detection of miRNA-122. More importantly, the substrate exhibited excellent controllability, reversibility and reproducibility through SDR and magnetic separation (modes II and III), especially sequence-independence for hairpin probes in mode III, holding great potential for the development of a versatile platform for optical biosensing.Herein, a cascaded chemiluminescence resonance energy transfer (C-CRET) process was demonstrated from horseradish peroxidase (HRP)-mimicking DNAzyme-catalyzed luminol-H2O2 to fluorescein and further to graphene oxide (GO) when HRP-mimicking DNAzyme/fluorescein was in close proximity to the GO surface. The proposed C-CRET system was successfully implemented to construct three modes of C-CRET hot-spot-active substrates (modes I, II and III) by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs (hot-spot-generation probes) on magnetic GO (MGO), resulting in a signal ``off'' state due to the quenching of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122 (miRNA-122), the targets (mode I) or the new triggers that were generated through a strand displacement reaction (SDR) initiated by miRNA-122 (modes II and III) hybridized with the loop domains of hairpin probes on MGO to form double-stranded (modes I and II) or triplex-stem structures (mode III), causing an ``open'' configuration of the hairpin probe and a CRET signal ``on'' state, thus achieving sensitive and selective detection of miRNA-122. More importantly, the substrate exhibited excellent controllability, reversibility and reproducibility through SDR and magnetic separation (modes II and III), especially sequence-independence for hairpin probes in mode III, holding great potential for the development of a versatile platform for optical biosensing. Electronic supplementary information (ESI) available: Sequences of RNA and DNA used in this study, relationship of the proposed three modes, CRET mechanism of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein system, calculation of the surface coverage of hairpin probe I-1 on MGO, control experiment, comparison between different modes for microRNA detection, and advantages of the proposed strategy. See DOI: 10.1039/c4nr06603k

Evaluation of pavement bleeding problem on I-55 in Illinois

DOT National Transportation Integrated Search

1991-01-01

Shortly after construction fat spots began to appear throughout the project on a 3 inch hot mix asphalt (HMA) overlay of an existing PCC pavement. The fat spots appeared to occur at end of truck loads. After time the fat spots developed into potholes...

Mutations in Protein-Binding Hot-Spots on the Hub Protein Smad3 Differentially Affect Its Protein Interactions and Smad3-Regulated Gene Expression

PubMed Central

Schiro, Michelle M.; Stauber, Sara E.; Peterson, Tami L.; Krueger, Chateen; Darnell, Steven J.; Satyshur, Kenneth A.; Drinkwater, Norman R.; Newton, Michael A.; Hoffmann, F. Michael

2011-01-01

Background Hub proteins are connected through binding interactions to many other proteins. Smad3, a mediator of signal transduction induced by transforming growth factor beta (TGF-β), serves as a hub protein for over 50 protein-protein interactions. Different cellular responses mediated by Smad3 are the product of cell-type and context dependent Smad3-nucleated protein complexes acting in concert. Our hypothesis is that perturbation of this spectrum of protein complexes by mutation of single protein-binding hot-spots on Smad3 will have distinct consequences on Smad3-mediated responses. Methodology/Principal Findings We mutated 28 amino acids on the surface of the Smad3 MH2 domain and identified 22 Smad3 variants with reduced binding to subsets of 17 Smad3-binding proteins including Smad4, SARA, Ski, Smurf2 and SIP1. Mutations defective in binding to Smad4, e.g., D408H, or defective in nucleocytoplasmic shuttling, e.g., W406A, were compromised in modulating the expression levels of a Smad3-dependent reporter gene or six endogenous Smad3-responsive genes: Mmp9, IL11, Tnfaip6, Fermt1, Olfm2 and Wnt11. However, the Smad3 mutants Y226A, Y297A, W326A, K341A, and E267A had distinct differences on TGF-β signaling. For example, K341A and Y226A both reduced the Smad3-mediated activation of the reporter gene by ∼50% but K341A only reduced the TGF-β inducibilty of Olfm2 in contrast to Y226A which reduced the TGF-β inducibility of all six endogenous genes as severely as the W406A mutation. E267A had increased protein binding but reduced TGF-β inducibility because it caused higher basal levels of expression. Y297A had increased TGF-β inducibility because it caused lower Smad3-induced basal levels of gene expression. Conclusions/Significance Mutations in protein binding hot-spots on Smad3 reduced the binding to different subsets of interacting proteins and caused a range of quantitative changes in the expression of genes induced by Smad3. This approach should be useful for unraveling which Smad3 protein complexes are critical for specific biological responses. PMID:21949838

Mutations in protein-binding hot-spots on the hub protein Smad3 differentially affect its protein interactions and Smad3-regulated gene expression.

PubMed

Schiro, Michelle M; Stauber, Sara E; Peterson, Tami L; Krueger, Chateen; Darnell, Steven J; Satyshur, Kenneth A; Drinkwater, Norman R; Newton, Michael A; Hoffmann, F Michael

2011-01-01

Hub proteins are connected through binding interactions to many other proteins. Smad3, a mediator of signal transduction induced by transforming growth factor beta (TGF-β), serves as a hub protein for over 50 protein-protein interactions. Different cellular responses mediated by Smad3 are the product of cell-type and context dependent Smad3-nucleated protein complexes acting in concert. Our hypothesis is that perturbation of this spectrum of protein complexes by mutation of single protein-binding hot-spots on Smad3 will have distinct consequences on Smad3-mediated responses. We mutated 28 amino acids on the surface of the Smad3 MH2 domain and identified 22 Smad3 variants with reduced binding to subsets of 17 Smad3-binding proteins including Smad4, SARA, Ski, Smurf2 and SIP1. Mutations defective in binding to Smad4, e.g., D408H, or defective in nucleocytoplasmic shuttling, e.g., W406A, were compromised in modulating the expression levels of a Smad3-dependent reporter gene or six endogenous Smad3-responsive genes: Mmp9, IL11, Tnfaip6, Fermt1, Olfm2 and Wnt11. However, the Smad3 mutants Y226A, Y297A, W326A, K341A, and E267A had distinct differences on TGF-β signaling. For example, K341A and Y226A both reduced the Smad3-mediated activation of the reporter gene by ∼50% but K341A only reduced the TGF-β inducibilty of Olfm2 in contrast to Y226A which reduced the TGF-β inducibility of all six endogenous genes as severely as the W406A mutation. E267A had increased protein binding but reduced TGF-β inducibility because it caused higher basal levels of expression. Y297A had increased TGF-β inducibility because it caused lower Smad3-induced basal levels of gene expression. Mutations in protein binding hot-spots on Smad3 reduced the binding to different subsets of interacting proteins and caused a range of quantitative changes in the expression of genes induced by Smad3. This approach should be useful for unraveling which Smad3 protein complexes are critical for specific biological responses.

Eclipse cooling of selected lunar features

NASA Technical Reports Server (NTRS)

Shorthill, R. W.; Saari, J. M.; Baird, F. E.; Lecompte, J. R.

1970-01-01

Thermal measurements were made in the 10 to 12 micron band of the lunar surface during the total eclipse of December19, 1964. A normalized differential thermal contour map is included, showing the location of the thermal anomalies or hot spots on the disk and the eclipse cooling curves of 400 sites, of which more than 300 were hot spots. The eclipse cooling data is compared to a particulate thermophysical model of the soil.

Linewidth dependence of coherent terahertz emission from Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks in the hot-spot regime

NASA Astrophysics Data System (ADS)

Li, Mengyue; Yuan, Jie; Kinev, Nickolay; Li, Jun; Gross, Boris; Guénon, Stefan; Ishii, Akira; Hirata, Kazuto; Hatano, Takeshi; Koelle, Dieter; Kleiner, Reinhold; Koshelets, Valery P.; Wang, Huabing; Wu, Peiheng

2012-08-01

We report on measurements of the linewidth Δf of terahertz radiation emitted from intrinsic Josephson junction stacks, using a Nb/AlN/NbN integrated receiver for detection. Previous resolution-limited measurements indicated that Δf may be below 1 GHz—much smaller than expected from a purely cavity-induced synchronization. While at low bias we found Δf to be not smaller than ˜500 MHz, at high bias, where a hot spot coexists with regions which are still superconducting, Δf turned out to be as narrow as 23 MHz. We attribute this to the hot spot acting as a synchronizing element. Δf decreases with increasing bath temperature, a behavior reminiscent of motional narrowing in NMR or electron spin resonance (ESR), but hard to explain in standard electrodynamic models of Josephson junctions.

Hot spot temperature measurements in DT layered implosions

NASA Astrophysics Data System (ADS)

Patel, Pravesh; Ma, T.; Macphee, A.; Callahan, D.; Chen, H.; Cerjan, C.; Clark, D.; Edgell, D.; Hurricane, O.; Izumi, N.; Khan, S.; Jarrott, L.; Kritcher, A.; Springer, P.

2015-11-01

The temperature of the burning DT hot spot in an ICF implosion is a crucial parameter in understanding the thermodynamic conditions of the fuel at stagnation and and the performance of the implosion in terms of alpha-particle self-heating and energy balance. The continuum radiation spectrum emitted from the hot spot provides an accurate measure of the emissivity-weighted electron temperature. Absolute measurements of the emitted radiation are made with several independent instruments including spatially-resolved broadband imagers, and space- and time-integrated monochromatic detectors. We present estimates of the electron temperature in DT layered implosions derived from the radiation spectrum most consistent with the available measurements. The emissivity-weighted electron temperatures are compared to the neutron-averaged apparent ion temperatures inferred from neutron time-of-flight detectors. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Consideration of IP Telephony Quality on the IEEE802.11a Wireless LAN

NASA Astrophysics Data System (ADS)

Miyashita, Michifumi; Takamatsu, Hideyuki; Kurono, Masahiro

Recently, IP telephony services in wired network are started, and paid attention for its charge-free nature due to IP technology. On the other hand, the Hot-Spot service, which provides one to access the Internet at the public space such as cafe, using the IEEE wireless LAN has been evolved, and it is expected that the IP telephony service on the Hot-Spot network will be developed. However, the IP telephony quality on the IEEE802.11a wireless LAN has not been fully studied yet. In this paper, we discuss about the quality of IP telephony service on the IEEE802.11a wireless LAN from the aspect of R-value, and show ability to improve the IP telephony quality on the Hot-Spot network employing PLC function defined in the ITU-T Recommendation G.711 Appendix I.

Plasma behaviour in the neighbourhood of the hot-spot during an active experiment

NASA Astrophysics Data System (ADS)

Sallago, Patricia

In order to study the physical quantities that characterize a plasma, several active experiments have been done by many researcher groups around the world. These experimental papers, describing their measurements and the observed phenomena under a variety of geomagnetical conditions, bring some clues about the plasma behaviour in the neighbourhood of the hot-spot during and soon after the turn-off of ionospheric heating devices. A review of these works was faced in the frame of the application of IAR (Argentinian Radioas-tronomy Institute), La Plata, Argentine, as a site of installation for the AMISR (Advanced Modular Incoherent Scatter Radar), in a contest of research projets called by NSF (National Scientific Foundation). The present contribution gives a possible theoretical explanation, based on the generation and propagation of Alfven waves, of the plasma behaviour in the neighbourhood of the hot-spot during an active experiment and, as a consequence, for some experimental results.

Onset of hydrodynamic mix in high-velocity, highly compressed inertial confinement fusion implosions.

PubMed

Ma, T; Patel, P K; Izumi, N; Springer, P T; Key, M H; Atherton, L J; Benedetti, L R; Bradley, D K; Callahan, D A; Celliers, P M; Cerjan, C J; Clark, D S; Dewald, E L; Dixit, S N; Döppner, T; Edgell, D H; Epstein, R; Glenn, S; Grim, G; Haan, S W; Hammel, B A; Hicks, D; Hsing, W W; Jones, O S; Khan, S F; Kilkenny, J D; Kline, J L; Kyrala, G A; Landen, O L; Le Pape, S; MacGowan, B J; Mackinnon, A J; MacPhee, A G; Meezan, N B; Moody, J D; Pak, A; Parham, T; Park, H-S; Ralph, J E; Regan, S P; Remington, B A; Robey, H F; Ross, J S; Spears, B K; Smalyuk, V; Suter, L J; Tommasini, R; Town, R P; Weber, S V; Lindl, J D; Edwards, M J; Glenzer, S H; Moses, E I

2013-08-23

Deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility have demonstrated yields ranging from 0.8 to 7×10(14), and record fuel areal densities of 0.7 to 1.3 g/cm2. These implosions use hohlraums irradiated with shaped laser pulses of 1.5-1.9 MJ energy. The laser peak power and duration at peak power were varied, as were the capsule ablator dopant concentrations and shell thicknesses. We quantify the level of hydrodynamic instability mix of the ablator into the hot spot from the measured elevated absolute x-ray emission of the hot spot. We observe that DT neutron yield and ion temperature decrease abruptly as the hot spot mix mass increases above several hundred ng. The comparison with radiation-hydrodynamic modeling indicates that low mode asymmetries and increased ablator surface perturbations may be responsible for the current performance.

Hotspot electron temperature from x-ray continuum measurements on the NIF

NASA Astrophysics Data System (ADS)

Jarrott, L. C.; Benedetti, L. R.; Chen, H.; Izumi, N.; Khan, S. F.; Ma, T.; Nagel, S. R.; Landen, O. L.; Pak, A.; Patel, P. K.; Schneider, M.; Scott, H. A.

2016-11-01

We report on measurements of the electron temperature in the hotspot of inertially confined, layered, spherical implosions on the National Ignition Facility using a differential filtering diagnostic. Measurements of the DT and DD ion temperatures using neutron time-of-flight detectors are complicated by the contribution of hot spot motion to the peak width, which produce an apparent temperature higher than the thermal temperature. The electron temperature is not sensitive to this non-thermal velocity and is thus a valuable input to interpreting the stagnated hot spot conditions. Here we show that the current differential filtering diagnostic provides insufficient temperature resolution for the hot spot temperatures of interest. We then propose a new differential filter configuration utilizing larger pinhole size to increase spectral fluence, as well as thicker filtration. This new configuration will improve measurement uncertainty by more than a factor of three, allowing for a more accurate hotspot temperature.

Universal Scaling of Robust Thermal Hot Spot and Ionic Current Enhancement by Focused Ohmic Heating in a Conic Nanopore

PubMed Central

Pan, Zehao; Wang, Ceming; Li, Meng; Chang, Hsueh-Chia

2017-01-01

A stable nanoscale thermal hot spot, with temperature approaching 100 °C, is shown to be sustained by localized Ohmic heating of a focused electric field at the tip of a slender conic nanopore. The self-similar (length-independent) conic geometry allows us to match the singular heat source at the tip to the singular radial heat loss from the slender cone to obtain a self-similar steady temperature profile along the cone and the resulting ionic current conductance enhancement due to viscosity reduction. The universal scaling, which depends only on a single dimensionless parameter Z, collapses the measured conductance data and computed temperature profiles in ion-track conic nanopores and conic nanopipettes. The collapsed numerical data reveal universal values for the hot-spot location and temperature in an aqueous electrolyte. PMID:27715110

Hot spots, indicator taxa, complementarity and optimal networks of taiga.

PubMed Central

Virolainen, K M; Ahlroth, P; Hyvärinen, E; Korkeamäki, E; Mattila, J; Päiivinen, J; Rintala, T; Suomi, T; Suhonen, J

2000-01-01

If hot spots for different taxa coincide, priority-setting surveys in a region could be carried out more cheaply by focusing on indicator taxa. Several previous studies show that hot spots of different taxa rarely coincide. However, in tropical areas indicator taxa may be used in selecting complementary networks to represent biodiversity as a whole. We studied beetles (Coleoptera), Heteroptera, polypores or bracket fungi (Polyporaceae) and vascular plants of old growth boreal taiga forests. Optimal networks for Heteroptera maximized the high overall species richness of beetles and vascular plants, but these networks were least favourable options for polypores. Polypores are an important group indicating the conservation value of old growth taiga forests. Random selection provided a better option. Thus, certain groups may function as good indicators for maximizing the overall species richness of some taxonomic groups, but all taxa should be examined separately. PMID:10885520

Structural hot spots for the solubility of globular proteins

PubMed Central

Ganesan, Ashok; Siekierska, Aleksandra; Beerten, Jacinte; Brams, Marijke; Van Durme, Joost; De Baets, Greet; Van der Kant, Rob; Gallardo, Rodrigo; Ramakers, Meine; Langenberg, Tobias; Wilkinson, Hannah; De Smet, Frederik; Ulens, Chris; Rousseau, Frederic; Schymkowitz, Joost

2016-01-01

Natural selection shapes protein solubility to physiological requirements and recombinant applications that require higher protein concentrations are often problematic. This raises the question whether the solubility of natural protein sequences can be improved. We here show an anti-correlation between the number of aggregation prone regions (APRs) in a protein sequence and its solubility, suggesting that mutational suppression of APRs provides a simple strategy to increase protein solubility. We show that mutations at specific positions within a protein structure can act as APR suppressors without affecting protein stability. These hot spots for protein solubility are both structure and sequence dependent but can be computationally predicted. We demonstrate this by reducing the aggregation of human α-galactosidase and protective antigen of Bacillus anthracis through mutation. Our results indicate that many proteins possess hot spots allowing to adapt protein solubility independently of structure and function. PMID:26905391

Hot-spot contributions in shocked high explosives from mesoscale ignition models

NASA Astrophysics Data System (ADS)

Levesque, G.; Vitello, P.; Howard, W. M.

2013-06-01

High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing the population of mesoscale hot spots that are active in the shocked ignition of explosives is important for the development of predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with a chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. Implementing first-principles based decomposition kinetics, burning hot spots are monitored, and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive 1,3,5-triamino-2,4,6-trinitrobenzene.

Rapid experimental SAD phasing and hot-spot identification with halogenated fragments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauman, Joseph D.; Harrison, Jerry Joe E. K.; Arnold, Eddy

2016-01-01

Through X-ray crystallographic fragment screening, 4-bromopyrazole was discovered to be a `magic bullet' that is capable of binding at many of the ligand `hot spots' found in HIV-1 reverse transcriptase (RT). The binding locations can be in pockets that are `hidden' in the unliganded crystal form, allowing rapid identification of these sites forin silicoscreening. In addition to hot-spot identification, this ubiquitous yet specific binding provides an avenue for X-ray crystallographic phase determination, which can be a significant bottleneck in the determination of the structures of novel proteins. The anomalous signal from 4-bromopyrazole or 4-iodopyrazole was sufficient to determine the structuresmore » of three proteins (HIV-1 RT, influenza A endonuclease and proteinase K) by single-wavelength anomalous dispersion (SAD) from single crystals. Both compounds are inexpensive, readily available, safe and very soluble in DMSO or water, allowing efficient soaking into crystals.« less

Hotspot electron temperature from x-ray continuum measurements on the NIF.

PubMed

Jarrott, L C; Benedetti, L R; Chen, H; Izumi, N; Khan, S F; Ma, T; Nagel, S R; Landen, O L; Pak, A; Patel, P K; Schneider, M; Scott, H A

2016-11-01

We report on measurements of the electron temperature in the hotspot of inertially confined, layered, spherical implosions on the National Ignition Facility using a differential filtering diagnostic. Measurements of the DT and DD ion temperatures using neutron time-of-flight detectors are complicated by the contribution of hot spot motion to the peak width, which produce an apparent temperature higher than the thermal temperature. The electron temperature is not sensitive to this non-thermal velocity and is thus a valuable input to interpreting the stagnated hot spot conditions. Here we show that the current differential filtering diagnostic provides insufficient temperature resolution for the hot spot temperatures of interest. We then propose a new differential filter configuration utilizing larger pinhole size to increase spectral fluence, as well as thicker filtration. This new configuration will improve measurement uncertainty by more than a factor of three, allowing for a more accurate hotspot temperature.

Pole of rotating analysis of present-day Juan de Fuca plate motion

NASA Technical Reports Server (NTRS)

Nishimura, C.; Wilson, D. S.; Hey, R. N.

1984-01-01

Convergence rates between the Juan de Fuca and North American plates are calculated by means of their relative, present-day pole of rotation. A method of calculating the propagation of errors in addition to the instantaneous poles of rotation is also formulated and applied to determine the Euler pole for Pacific-Juan de Fuca. This pole is vectorially added to previously published poles for North America-Pacific and 'hot spot'-Pacific to obtain North America-Juan de Fuca and 'hot spot'-Juan de Fuca, respectively. The errors associated with these resultant poles are determined by propagating the errors of the two summed angular velocity vectors. Under the assumption that hot spots are fixed with respect to a mantle reference frame, the average absolute velocity of the Juan de Puca plate is computed at approximately 15 mm/yr, thereby making it the slowest-moving of the oceanic plates.

Tuning and Switching Enantioselectivity of Asymmetric Carboligation in an Enzyme through Mutational Analysis of a Single Hot Spot.

PubMed

Wechsler, Cindy; Meyer, Danilo; Loschonsky, Sabrina; Funk, Lisa-Marie; Neumann, Piotr; Ficner, Ralf; Brodhun, Florian; Müller, Michael; Tittmann, Kai

2015-12-01

Enantioselective bond making and breaking is a hallmark of enzyme action, yet switching the enantioselectivity of the reaction is a difficult undertaking, and typically requires extensive screening of mutant libraries and multiple mutations. Here, we demonstrate that mutational diversification of a single catalytic hot spot in the enzyme pyruvate decarboxylase gives access to both enantiomers of acyloins acetoin and phenylacetylcarbinol, important pharmaceutical precursors, in the case of acetoin even starting from the unselective wild-type protein. Protein crystallography was used to rationalize these findings and to propose a mechanistic model of how enantioselectivity is controlled. In a broader context, our studies highlight the efficiency of mechanism-inspired and structure-guided rational protein design for enhancing and switching enantioselectivity of enzymatic reactions, by systematically exploring the biocatalytic potential of a single hot spot. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Calculated occultation profiles of Io and the hot spots

NASA Technical Reports Server (NTRS)

Mcewen, A. S.; Soderblom, L. A.; Matson, D. L.; Johnson, T. V.; Lunine, J. I.

1986-01-01

Occultations of Io by other Galilean satellites in 1985 provide a means to locate volcanic hot spots and to model their temperatures. The expected time variations in the integral reflected and emitted radiation of the occultations are computed as a function of wavelength (visual to 8.7 microns). The best current ephemerides were used to calculate the geometry of each event as viewed from earth. Visual reflectances were modeled from global mosaics of Io. Thermal emission from the hot spots was calculated from Voyager 1 IRIS observations and, for regions unobserved by IRIS, from a model based on the distribution of low-albedo features. The occultations may help determine (1) the location and temperature distribution of Loki; (2) the source(s) of excess emission in the region from long 50 deg to 200 deg and (3) the distribution of small, high-temperature sources.

Tidal dissipation, surface heat flow, and figure of viscoelastic models of Io

NASA Technical Reports Server (NTRS)

Segatz, M.; Spohn, T.; Ross, M. N.; Schubert, G.

1988-01-01

The deformation of Io, the tidal dissipation rate, and its interior spatial distribution are investigated by means of numerical simulations based on (1) a three-layer model (with dissipation in the mantle) or (2) a four-layer model (with dissipation in the asthenosphere). The mathematical derivation of the models is outlined; the selection of the input-parameter values is explained; the results are presented in extensive graphs and contour maps; and the constraints imposed on the models by observational data on the hot-spot distribution, tidal deformation, and gravity field are discussed in detail. It is found that both dissipation mechanisms may play a role on Io: model (2) is better able to explain the concentration of hot spots near the equator, while the presence of a large hot spot near the south pole (if confirmed by observations) would favor model (1).

Diagnosing and controlling mix in National Ignition Facility implosion experiments a)

NASA Astrophysics Data System (ADS)

Hammel, B. A.; Scott, H. A.; Regan, S. P.; Cerjan, C.; Clark, D. S.; Edwards, M. J.; Epstein, R.; Glenzer, S. H.; Haan, S. W.; Izumi, N.; Koch, J. A.; Kyrala, G. A.; Landen, O. L.; Langer, S. H.; Peterson, K.; Smalyuk, V. A.; Suter, L. J.; Wilson, D. C.

2011-05-01

High mode number instability growth of "isolated defects" on the surfaces of National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] capsules can be large enough for the perturbation to penetrate the imploding shell, and produce a jet of ablator material that enters the hot-spot. Since internal regions of the CH ablator are doped with Ge, mixing of this material into the hot-spot results in a clear signature of Ge K-shell emission. Evidence of jets entering the hot-spot has been recorded in x-ray images and spectra, consistent with simulation predictions [Hammel et al., High Energy Density Phys. 6, 171 (2010)]. Ignition targets have been designed to minimize instability growth, and capsule fabrication improvements are underway to reduce "isolated defects." An experimental strategy has been developed where the final requirements for ignition targets can be adjusted through direct measurements of mix and experimental tuning.

Design of Hybrid Nanostructural Arrays to Manipulate SERS-Active Substrates by Nanosphere Lithography.

PubMed

Zhao, Xiaoyu; Wen, Jiahong; Zhang, Mengning; Wang, Dunhui; Wang, Yaxin; Chen, Lei; Zhang, Yongjun; Yang, Jinghai; Du, Youwei

2017-03-01

An easy-handling and low-cost method is utilized to controllably fabricate nanopattern arrays as the surface-enhanced Raman scattering (SERS) active substrates with high density of SERS-active areas (hot spots). A hybrid silver array of nanocaps and nanotriangles are prepared by combining magnetron sputtering and plasma etching. By adjusting the etching time of polystyrene (PS) colloid spheres array in silver nanobowls, the morphology of the arrays can be easily manipulated to control the formation and distribution of hot spots. The experimental results show that the hybrid nanostructural arrays have large enhancement factor, which is estimated to be seven times larger than that in the array of nanocaps and three times larger than that in the array of nanorings and nanoparticles. According to the results of finite-difference time-domain simulation, the excellent SERS performance of this array is ascribed to the high density of hot spots and enhanced electromagnetic field.

Simulation of zones of contribution to wells at site GM–38, Naval Weapons Industrial Reserve Plant, Bethpage, New York

USGS Publications Warehouse

Misut, Paul

2014-01-01

A three-dimensional groundwater-flow model is coupled with the particle-tracking program MODPATH to delineate zones of contribution to wells pumping from the Magothy aquifer and supplying water to a chlorinated volatile organic compound removal plant at site GM–38, Naval Weapons Industrial Reserve Plant, Bethpage, New York. By use of driller’s logs, a transitional probability approach generated three alternative realizations of heterogeneity within the Magothy aquifer to assess uncertainty in model representation. Finer-grained sediments with low hydraulic conductivity were realized as laterally discontinuous, thickening towards the south, and comprising about 17 percent of the total aquifer volume. Particle-tracking evaluations of a steady state present conditions model with alternative heterogeneity realizations were used to develop zones of contribution of remedial pumping wells. Because of heterogeneity and high rates of advection within the coarse-grained sediments, transport by dispersion and (or) diffusion was assumed to be negligible. Resulting zones of contribution of existing remedial wells are complex shapes, influenced by heterogeneity of each realization and other nearby hydrologic stresses. The use of two particle tracking techniques helped identify zones of contribution to wells. Backtracking techniques and observations of points of intersection of backward-tracked particles at shells of the GM–38 Hot Spot, as defined by surfaces of equal total volatile organic compound concentration, identified the source of water within the GM–38 Hot Spot to simulated wells. Forward-tracking techniques identified the fate of water within the GM–38 Hot Spot, including well capture and discharge to model constant head and drain boundaries. The percentage of backward-tracked particles, started at GM–38 wells that were sourced from within the Hot Spot, varied from 72.0 to 98.2, depending on the Hot Spot delineation used (present steady state model and Magothy aquifer heterogeneity realization A). The percentage of forward-tracked particles that were captured by GM–38 wells varied from 81.1 to 94.6, depending on the Hot Spot delineation used, with the remainder primarily captured by Bethpage Water District Plant 4 production wells (present steady state model and Magothy aquifer heterogeneity realization A). Less than 1 percent of forward-tracked particles ultimately discharge at model constant head and drain boundaries. The differences between forward- and backward-tracked particle percentage ranges are due to some forward-tracked particles not being captured by GM–38 wells, and some backward-tracked particles not intersecting specific regions of the Hot Spot. During 2013, an aquifer test generated detailed time series of well pumping rates and corresponding water-level responses were recorded at numerous locations. These data were used to verify the present conditions steady state model and demonstrate the sensitivity of model results to transient-state changes.

Two strains of male-killing Wolbachia in a ladybird, Coccinella undecimpunctata, from a hot climate.

PubMed

Elnagdy, Sherif; Messing, Susan; Majerus, Michael E N

2013-01-01

Ladybirds are a hot-spot for the invasion of male-killing bacteria. These maternally inherited endosymbionts cause the death of male host embryos, to the benefit of female sibling hosts and the bacteria that they contain. Previous studies have shown that high temperatures can eradicate male-killers from ladybirds, leaving the host free from infection. Here we report the discovery of two maternally inherited sex ratio distorters in populations of a coccinellid, Coccinella undecimpunctata, from a hot lowland region of the Middle East. DNA sequence analysis indicates that the male killing is the result of infection by Wolbachia, that the trait is tetracycline sensitive, and that two distinct strains of Wolbachia co-occur within one beetle population. We discuss the implications of these findings for theories of male-killing and suggest avenues for future field-work on this system.

Two Strains of Male-Killing Wolbachia in a Ladybird, Coccinella undecimpunctata, from a Hot Climate

PubMed Central

Elnagdy, Sherif; Messing, Susan

2013-01-01

Ladybirds are a hot-spot for the invasion of male-killing bacteria. These maternally inherited endosymbionts cause the death of male host embryos, to the benefit of female sibling hosts and the bacteria that they contain. Previous studies have shown that high temperatures can eradicate male-killers from ladybirds, leaving the host free from infection. Here we report the discovery of two maternally inherited sex ratio distorters in populations of a coccinellid, Coccinella undecimpunctata, from a hot lowland region of the Middle East. DNA sequence analysis indicates that the male killing is the result of infection by Wolbachia, that the trait is tetracycline sensitive, and that two distinct strains of Wolbachia co-occur within one beetle population. We discuss the implications of these findings for theories of male-killing and suggest avenues for future field-work on this system. PMID:23349831

Research on Forming Mechanisms and Controlling Measurements for Surface Light Spot Defects of Galvanizing Steel Coils for Automobile Use

NASA Astrophysics Data System (ADS)

Guangmin, Wei; Haiyan, Sun; Jianqiang, Shi; Lianxuan, Wang; Haihong, Wu

When producing high surface quality galvanizing steel coils for automobile use, there are always many light spots on the surface since Hansteel CGL No.1 has been put into operation. The defect samples were analyzed by SEM and EDS. The result shows that cause for light spot is not only one. There are more Mn and P in high strength auto sheet, which can result in difficulty to be cleaned off the oxide on the hot rolled coils, so the defects coming. This is why the defects come with high strength auto sheet. When coils galvanized, the defects can't be covered up. To the contrary, the defects will be more obvious when zinc growing on the surface. And sometimes zinc or residue can adhere to work rolls when strips passing through SPM. The deposits then press normal coating. So the light spots come more. When the defect comes from pressing, there is no defect on steel base. The causation is found and measures were taken including high pressure cleaning equipments adopted. Result shows that the defects disappeared.

Effects of Laser Frequency and Multiple Beams on Hot Electron Generation in Fast Ignition

NASA Astrophysics Data System (ADS)

Royle, Ryan B.

Inertial confinement fusion (ICF) is one approach to harnessing fusion power for the purpose of energy production in which a small deuterium-tritium capsule is imploded to about a thousand times solid density with ultra-intense lasers. In the fast ignition (FI) scheme, a picosecond petawatt laser pulse is used to deposit ˜10 kJ of energy in ˜10 ps into a small hot-spot at the periphery of the compressed core, igniting a fusion burn wave. FI promises a much higher energy gain over the conventional central hot-spot ignition scheme in which ignition is achieved through compression alone. Sufficient energy coupling between ignition laser and implosion core is critical for the feasibility of the FI scheme. Laser-core energy coupling is mediated by hot electrons which absorb laser energy near the critical density and propagate to the dense core, depositing their energy primarily through collisions. The hot electron energy distribution plays a large role in achieving efficient energy coupling since electrons with energy much greater than a few MeV will only deposit a small fraction of their energy into the hot-spot region due to reduced collisional cross section. It is understood that it may be necessary to use the second or third harmonic of the 1.05 mum Nd glass laser to reduce the average hot electron energy closer to the few-MeV range. Also, it is likely that multiple ignition beams will be used to achieve the required intensities. In this study, 2D particle-in-cell simulations are used to examine the effects of frequency doubling and tripling of a 1 mum laser as well as effects of using various dual-beam configurations. While the hot-electron energy spectrum is indeed shifted closer to the few-MeV range for higher frequency beams, the overall energy absorption is reduced, canceling the gain from higher efficiency. For a fixed total laser input energy, we find that the amount of hot electron energy able to be deposited into the core hot-spot is fairly insensitive to the laser configuration used. Our results hint that the more important issue at hand may be divergence and transport of the hot electrons, which tend to spray into 2pi radians due to instabilities and current filamentation present in the laser-plasma interaction region.

Sodium Chloride Crystal-Induced SERS Platform for Controlled Highly Sensitive Detection of Illicit Drugs.

PubMed

Yu, Borong; Li, Pan; Zhou, Binbin; Tang, Xianghu; Li, Shaofei; Yang, Liangbao

2018-04-03

A sodium chloride crystal-driven spontaneous 'hot spot' structure was demonstrated as a SERS-active platform, to get reproducible SERS signals, and eliminate the need for mapping large areas, in comparison with solution phase testing. During the process of solvent evaporation, the crystals produced induced silver aggregates to assemble around themselves. The micro-scale crystals can also act as a template to obtain an optical position, such that the assembled hot area is conveniently located during SERS measurements. More importantly, the chloride ions added in colloids can also replace the citrate and on the surface of the silver sol, and further decrease the background interference. High quality SERS spectra from heroin, methamphetamine (MAMP), and cocaine have been obtained on the crystal-driven hot spot structure with high sensitivity and credible reproducibility. This approach can not only bring the nanoparticles to form plasmonic hot spots in a controlled way, and thus provide high sensitivity, but also potentially be explored as an active substrate for label-free detection of other illicit drugs or additives. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hot Spots and Hot Moments of Nitrogen in a Riparian Corridor

NASA Astrophysics Data System (ADS)

Dwivedi, Dipankar; Arora, Bhavna; Steefel, Carl I.; Dafflon, Baptiste; Versteeg, Roelof

2018-01-01

We use 3-D high-resolution reactive transport modeling to investigate whether the spatial distribution of organic-carbon-rich and chemically reduced sediments located in the riparian zone and temporal variability in groundwater flow direction impact the formation and distribution of nitrogen hot spots (regions that exhibit higher reaction rates when compared to other locations nearby) and hot moments (times that exhibit high reaction rates as compared to longer intervening time periods) within the Rifle floodplain in Colorado. Groundwater flows primarily toward the Colorado River from the floodplain but changes direction at times of high river stage. The result is that oxic river water infiltrates the Rifle floodplain during these relatively short-term events. Simulation results indicate that episodic rainfall in the summer season leads to the formation of nitrogen hot moments associated with Colorado River rise and resulting river infiltration into the floodplain. The results further demonstrate that the naturally reduced zones (NRZs) present in sediments of the Rifle floodplain have a higher potential for nitrate removal, approximately 70% greater than non-NRZs for typical hydrological conditions. During river water infiltration, nitrate reduction capacity remains the same within the NRZs, however, these conditions impact non-NRZs to a greater extent (approximately 95% less nitrate removal). Model simulations indicate chemolithoautotrophs are primarily responsible for the removal of nitrate in the Rifle floodplain. These nitrogen hot spots and hot moments are sustained by microbial respiration and the chemolithoautotrophic oxidation of reduced minerals in the riparian zone.

Self-defrosting recuperative air-to-air heat exchanger

DOEpatents

Drake, Richard L.

1993-01-01

A heat exchanger includes a stationary spirally or concentrically wound heat exchanger core with rotating baffles on upper and lower ends thereof. The rotating baffles include rotating inlets and outlets which are in communication with respective fixed inlets and outlets via annuli. The rotation of the baffles causes a concurrent rotation of the temperature distribution within the stationary exchanger core, thereby preventing frost build-up in some applications and preventing the formation of hot spots in other applications.

Monitoring of metal pollution in waterways across Bangladesh and ecological and public health implications of pollution.

PubMed

Kibria, Golam; Hossain, Md Maruf; Mallick, Debbrota; Lau, T C; Wu, Rudolf

2016-12-01

Using innovative artificial mussels technology for the first time, this study detected eight heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, U, Zn) on a regular basis in waterways across Bangladesh (Chittagong, Dhaka and Khulna). Three heavy metals, viz. Co, Cr and Hg were always below the instrumental detection levels in all the sites during the study period. Through this study, seven metal pollution "hot spots" have been identified, of which, five "hot spots" (Cu, Fe, Mn, Ni, Pb) were located in the Buriganga River, close to the capital Dhaka. Based on this study, the Buriganga River can be classified as the most polluted waterway in Bangladesh compared to waterways monitored in Khulna and Chittagong. Direct effluents discharged from tanneries, textiles are, most likely, reasons for elevated concentrations of heavy metals in the Buriganga River. In other areas (Khulna), agriculture and fish farming effluents may have caused higher Cu, U and Zn in the Bhairab and Rupsa Rivers, whereas untreated industrial discharge and ship breaking activities can be linked to elevated Cd in the coastal sites (Chittagong). Metal pollution may cause significant impacts on water quality (irrigation, drinking), aquatic biodiversity (lethal and sub-lethal effects), food contamination/food security (bioaccumulation of metals in crops and seafood), human health (diseases) and livelihoods of people associated with wetlands. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of trends in experimental observables: Reconstruction of the implosion dynamics and implications for fusion yield extrapolation for direct-drive cryogenic targets on OMEGA

NASA Astrophysics Data System (ADS)

Bose, A.; Betti, R.; Mangino, D.; Woo, K. M.; Patel, D.; Christopherson, A. R.; Gopalaswamy, V.; Mannion, O. M.; Regan, S. P.; Goncharov, V. N.; Edgell, D. H.; Forrest, C. J.; Frenje, J. A.; Gatu Johnson, M.; Yu Glebov, V.; Igumenshchev, I. V.; Knauer, J. P.; Marshall, F. J.; Radha, P. B.; Shah, R.; Stoeckl, C.; Theobald, W.; Sangster, T. C.; Shvarts, D.; Campbell, E. M.

2018-06-01

This paper describes a technique for identifying trends in performance degradation for inertial confinement fusion implosion experiments. It is based on reconstruction of the implosion core with a combination of low- and mid-mode asymmetries. This technique was applied to an ensemble of hydro-equivalent deuterium-tritium implosions on OMEGA which achieved inferred hot-spot pressures ≈56 ± 7 Gbar [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)]. All the experimental observables pertaining to the core could be reconstructed simultaneously with the same combination of low and mid-modes. This suggests that in addition to low modes, which can cause a degradation of the stagnation pressure, mid-modes are present which reduce the size of the neutron and x-ray producing volume. The systematic analysis shows that asymmetries can cause an overestimation of the total areal density in these implosions. It is also found that an improvement in implosion symmetry resulting from correction of either the systematic mid or low modes would result in an increase in the hot-spot pressure from 56 Gbar to ≈ 80 Gbar and could produce a burning plasma when the implosion core is extrapolated to an equivalent 1.9 MJ symmetric direct illumination [Bose et al., Phys. Rev. E 94, 011201(R) (2016)].

Feasibility of field portable near infrared (NIR) spectroscopy to determine cyanide concentrations in soil

NASA Astrophysics Data System (ADS)

Sut, Magdalena; Fischer, Thomas; Repmann, Frank; Raab, Thomas

2013-04-01

In Germany, at more than 1000 sites, soil is polluted with an anthropogenic contaminant in form of iron-cyanide complexes. These contaminations are caused by former Manufactured Gas Plants (MGPs), where electricity for lighting was produced in the process of coal gasification. The production of manufactured gas was restrained in 1950, which caused cessation of MGPs. Our study describes the application of Polychromix Handheld Field Portable Near-Infrared (NIR) Analyzer to predict the cyanide concentrations in soil. In recent times, when the soil remediation is of major importance, there is a need to develop rapid and non-destructive methods for contaminant determination in the field. In situ analysis enables determination of 'hot spots', is cheap and time saving in comparison to laboratory methods. This paper presents a novel usage of NIR spectroscopy, where a calibration model was developed, using multivariate calibration algorithms, in order to determine NIR spectral response to the cyanide concentration in soil samples. As a control, the contaminant concentration was determined using conventional Flow Injection Analysis (FIA). The experiments revealed that portable near-infrared spectrometers could be a reliable device for identification of contamination 'hot spots', where cyanide concentration are higher than 2400 mg kg-1 in the field and >1750 mg kg-1 after sample preparation in the laboratory, but cannot replace traditional laboratory analyses due to high limits of detection.

Analysis of trends in experimental observables: Reconstruction of the implosion dynamics and implications for fusion yield extrapolation for direct-drive cryogenic targets on OMEGA

DOE PAGES

Bose, A.; Betti, R.; Mangino, D.; ...

2018-05-29

This paper describes a technique for identifying trends in performance degradation for inertial con finement fusion implosion experiments. It is based on reconstruction of the implosion core with a combination of low- and mid-mode asymmetries. This technique was applied to an ensemble of hydro-equivalent deuterium-tritium implosions on OMEGA that achieved inferred hot-spot pressures ≈56 ± 7 Gbar [S. Regan et al., Phys. Rev. Lett. 117, 025001 (2016)]. All the experimental observables pertaining to the core could be reconstructed simultaneously with the same combination of low and mid modes. This suggests that in addition to low modes, that can cause amore » degradation of the stagnation pressure, mid modes are present that reduce the size of the neutron and x-ray producing volume. The systematic analysis shows that asymmetries can cause an overestimation of the total areal density in these implosions. Finally, it is also found that an improvement in implosion symmetry resulting from correction of either the systematic mid or low modes would result in an increase of the hot-spot pressure from 56 Gbar to ≈ 80 Gbar and could produce a burning plasma when the implosion core is extrapolated to an equivalent 1.9 MJ symmetric direct illumination [A. Bose et al., Phys. Rev. E 94, 011201(R) (2016)].« less

Analysis of trends in experimental observables: Reconstruction of the implosion dynamics and implications for fusion yield extrapolation for direct-drive cryogenic targets on OMEGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, A.; Betti, R.; Mangino, D.

This paper describes a technique for identifying trends in performance degradation for inertial con finement fusion implosion experiments. It is based on reconstruction of the implosion core with a combination of low- and mid-mode asymmetries. This technique was applied to an ensemble of hydro-equivalent deuterium-tritium implosions on OMEGA that achieved inferred hot-spot pressures ≈56 ± 7 Gbar [S. Regan et al., Phys. Rev. Lett. 117, 025001 (2016)]. All the experimental observables pertaining to the core could be reconstructed simultaneously with the same combination of low and mid modes. This suggests that in addition to low modes, that can cause amore » degradation of the stagnation pressure, mid modes are present that reduce the size of the neutron and x-ray producing volume. The systematic analysis shows that asymmetries can cause an overestimation of the total areal density in these implosions. Finally, it is also found that an improvement in implosion symmetry resulting from correction of either the systematic mid or low modes would result in an increase of the hot-spot pressure from 56 Gbar to ≈ 80 Gbar and could produce a burning plasma when the implosion core is extrapolated to an equivalent 1.9 MJ symmetric direct illumination [A. Bose et al., Phys. Rev. E 94, 011201(R) (2016)].« less

Spatial patterns of the congenital heart disease prevalence among 0- to 14-year-old children in Sichuan Basin, P. R China, from 2004 to 2009

PubMed Central

2014-01-01

Background Congenital heart disease (CHD) is the most common type of major birth defects in Sichuan, the most populous province in China. The detailed etiology of CHD is unknown but some environmental factors are suspected as the cause of this disease. However, the geographical variations in CHD prevalence would be highly valuable in providing a clue on the role of the environment in CHD etiology. Here, we investigate the spatial patterns and geographic differences in CHD prevalence among 0- to 14-year-old children, discuss the possible environmental risk factors that might be associated with CHD prevalence in Sichuan Basin from 2004 to 2009. Methods The hierarchical Bayesian model was used to estimate CHD prevalence at the township level. Spatial autocorrelation statistics were performed, and a hot-spot analysis with different distance thresholds was used to identify the spatial pattern of CHD prevalence. Distribution and clustering maps were drawn using geographic information system tools. Results CHD prevalence was significantly clustered in Sichuan Basin in different spatial scale. Typical hot/cold clusters were identified, and possible CHD causes were discussed. The association between selected hypothetical environmental factors of maternal exposure and CHD prevalence was evaluated. Conclusions The largest hot-spot clustering phenomena and the CHD prevalence clustering trend among 0- to 14-year-old children in the study area showed a plausibly close similarity with those observed in the Tuojiang River Basin. The high ecological risk of heavy metal(Cd, As, and Pb)sediments in the middle and lower streams of the Tuojiang River watershed and ammonia–nitrogen pollution may have contribution to the high prevalence of CHD in this area. PMID:24924350

Genetic Diversity of Infectious Laryngotracheitis Virus during In Vivo Coinfection Parallels Viral Replication and Arises from Recombination Hot Spots within the Genome

PubMed Central

Hartley, Carol A.; Vaz, Paola K.; Diaz-Méndez, Andrés; García, Maricarmen; Spatz, Stephen; Devlin, Joanne M.

2017-01-01

ABSTRACT Recombination is a feature of many alphaherpesviruses that infect people and animals. Infectious laryngotracheitis virus (ILTV; Gallid alphaherpesvirus 1) causes respiratory disease in chickens, resulting in significant production losses in poultry industries worldwide. Natural (field) ILTV recombination is widespread, particularly recombination between attenuated ILTV vaccine strains to create virulent viruses. These virulent recombinants have had a major impact on animal health. Recently, the development of a single nucleotide polymorphism (SNP) genotyping assay for ILTV has helped to understand ILTV recombination in laboratory settings. In this study, we applied this SNP genotyping assay to further examine ILTV recombination in the natural host. Following coinoculation of specific-pathogen-free chickens, we examined the resultant progeny for evidence of viral recombination and characterized the diversity of the recombinants over time. The results showed that ILTV replication and recombination are closely related and that the recombinant viral progeny are most diverse 4 days after coinoculation, which is the peak of viral replication. Further, the locations of recombination breakpoints in a selection of the recombinant progeny, and in field isolates of ILTV from different geographical regions, were examined following full-genome sequencing and used to identify recombination hot spots in the ILTV genome. IMPORTANCE Alphaherpesviruses are common causes of disease in people and animals. Recombination enables genome diversification in many different species of alphaherpesviruses, which can lead to the evolution of higher levels of viral virulence. Using the alphaherpesvirus infectious laryngotracheitis virus (ILTV), we performed coinfections in the natural host (chickens) to demonstrate high levels of virus recombination. Higher levels of diversity in the recombinant progeny coincided with the highest levels of virus replication. In the recombinant progeny, and in field isolates, recombination occurred at greater frequency in recombination hot spot regions of the virus genome. Our results suggest that control measures that aim to limit viral replication could offer the potential to limit virus recombination and thus the evolution of virulence. The development and use of vaccines that are focused on limiting virus replication, rather than vaccines that are focused more on limiting clinical disease, may be indicated in order to better control disease. PMID:28939604