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Sample records for adhesive remnant index

  1. Effects of Two Soft Drinks on Shear Bond Strength and Adhesive Remnant Index of Orthodontic Metal Brackets

    PubMed Central

    Sajadi, Soodabeh Sadat; Eslami Amirabadi, Gholamreza; Sajadi, Sepideh

    2014-01-01

    Objective: Bond failure of brackets during orthodontic treatment is a common problem; which results in treatment interference, increased treatment time and prolonged clinical time for rebonding of failed brackets. The purpose of this study was to evaluate the effects of Coca-Cola and a non-alcoholic beer on the shear bond strength and adhesive remnant index (ARI) of orthodontic metal brackets in vitro. Materials and Methods: Eighty intact human premolars were divided into two experimental groups of Coca-Cola and non-alcoholic beer (Istak), and a control group of artificial saliva. Over a period of thirty days, the test groups were immersed in the respective soft drinks for 5 minutes, twice a day. For the remainder of the time, they were kept in artificial saliva at 37°C. The control group was stored in artificial saliva during the experiment. All samples were subjected to shearing forces using Universal Testing Machine. ARI was determined with a stereomicroscope at ×12 magnification. The data of shear bond strength were statistically analyzed by one-way ANOVA and Tukey’s Post-Hoc test and the data of ARI scores were analyzed by Kruskal-Wallis test. Results: No significant difference was observed in ARIs of the three groups (P≤ 0.552). The shear bond strength of Coke group was significantly lower than that of the two other groups (P≤ 0.035); but there was no significant difference between the shear bond strength of Istak and the control group (P≤ 0.999). Conclusion: Coca-Cola decreased the shear bond strength of orthodontic brackets. PMID:25584049

  2. A comparative study of qualitative and quantitative methods for the assessment of adhesive remnant after bracket debonding.

    PubMed

    Cehreli, S Burcak; Polat-Ozsoy, Omur; Sar, Cagla; Cubukcu, H Evren; Cehreli, Zafer C

    2012-04-01

    The amount of the residual adhesive after bracket debonding is frequently assessed in a qualitative manner, utilizing the adhesive remnant index (ARI). This study aimed to investigate whether quantitative assessment of the adhesive remnant yields more precise results compared to qualitative methods utilizing the 4- and 5-point ARI scales. Twenty debonded brackets were selected. Evaluation and scoring of the adhesive remnant on bracket bases were made consecutively using: 1. qualitative assessment (visual scoring) and 2. quantitative measurement (image analysis) on digital photographs. Image analysis was made on scanning electron micrographs (SEM) and high-precision elemental maps of the adhesive remnant as determined by energy dispersed X-ray spectrometry. Evaluations were made in accordance with the original 4-point and the modified 5-point ARI scales. Intra-class correlation coefficients (ICCs) were calculated, and the data were evaluated using Friedman test followed by Wilcoxon signed ranks test with Bonferroni correction. ICC statistics indicated high levels of agreement for qualitative visual scoring among examiners. The 4-point ARI scale was compliant with the SEM assessments but indicated significantly less adhesive remnant compared to the results of quantitative elemental mapping. When the 5-point scale was used, both quantitative techniques yielded similar results with those obtained qualitatively. These results indicate that qualitative visual scoring using the ARI is capable of generating similar results with those assessed by quantitative image analysis techniques. In particular, visual scoring with the 5-point ARI scale can yield similar results with both the SEM analysis and elemental mapping.

  3. Effect of adhesive remnant removal on enamel topography after bracket debonding

    PubMed Central

    Cardoso, Larissa Adrian Meira; Valdrighi, Heloísa Cristina; Vedovello, Mario; Correr, Américo Bortolazzo

    2014-01-01

    INTRODUCTION: At orthodontic treatment completion, knowledge about the effects of adhesive remnant removal on enamel is paramount. OBJECTIVE: This study aimed at assessing the effect of different adhesive remnant removal methods on enamel topography (ESI) and surface roughness (Ra) after bracket debonding and polishing. METHODS: A total of 50 human premolars were selected and divided into five groups according to the method used for adhesive remnant removal: high speed tungsten carbide bur (TCB), Sof-Lex discs (SL), adhesive removing plier (PL), ultrasound (US) and Fiberglass burs (FB). Metal brackets were bonded with Transbond XT, stored at 37oC for 24 hours before debonding with adhesive removing plier. Subsequently, removal methods were carried out followed by polishing with pumice paste. Qualitative and quantitative analyses were conducted with pre-bonding, post-debonding and post-polishing analyses. Results were submitted to statistical analysis with F test (ANOVA) and Tukey's (Ra) as well as with Kruskal-Wallis and Bonferroni tests (ESI) (P < 0.05). RESULTS: US Ra and ESI were significantly greater than TCB, SL, PL and FB. Polishing minimized Ra and ESI in the SL and FB groups. CONCLUSION: Adhesive remnant removal with SL and FB associated with polishing are recommended due to causing little damage to the enamel. PMID:25628087

  4. Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes

    PubMed Central

    2014-01-01

    Aims Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Material and methods Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. Results The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Conclusions Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well. PMID:25208969

  5. The modified equipartition calculation for supernova remnants with the spectral index α = 0.5

    NASA Astrophysics Data System (ADS)

    Urošević, Dejan; Pavlović, Marko Z.; Arbutina, Bojan; Dobardžić, Aleksandra

    2015-03-01

    Recently, the modified equipartition calculation for supernova remnants (SNRs) has been derived by Arbutina et al. (2012). Their formulae can be used for SNRs with the spectral indices between 0.5 < α < 1. Here, by using approximately the same analytical method, we derive the equipartition formulae useful for SNRs with spectral index α=0.5. These formulae represent next step upgrade of Arbutina et al. (2012) derivation, because among 30 Galactic SNRs with available observational parameters for the equipartition calculation, 16 have spectral index α = 0.5. For these 16 Galactic SNRs we calculated the magnetic field strengths which are approximately 40 per cent higher than those calculated by using Pacholczyk (1970) equipartition and similar to those calculated by using Beck & Krause (2005) calculation.

  6. Rayleigh-Taylor instabilities in Type Ia supernova remnants undergoing cosmic ray particle acceleration - low adiabatic index solutions

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Yueh

    2011-07-01

    This study investigates the evolution of Rayleigh-Taylor (R-T) instabilities in Type Ia supernova remnants that are associated with a low adiabatic index γ, where γ < 5/3, which reflects the expected change in the supernova shock structure as a result of cosmic ray particle acceleration. Extreme cases, such as the case with the maximum compression ratio that corresponds to γ= 1.1, are examined. As γ decreases, the shock compression ratio rises, and an increasingly narrow intershock region with a more pronounced initial mixture of R-T unstable gas is produced. Consequently, the remnant outline may be perturbed by small-amplitude, small-wavelength bumps. However, as the instability decays over time, the extent of convective mixing in terms of the ratio of the radius of the R-T fingers to the blast wave does not strongly depend on the value of γ for γ≥ 1.2. As a result of the age of the remnant, the unstable gas cannot extend sufficiently far to form metal-enriched filaments of ejecta material close to the periphery of Tycho's supernova remnant. The consistency of the dynamic properties of Tycho's remnant with the adiabatic model γ= 5/3 reveals that the injection of cosmic rays is too weak to alter the shock structure. Even with very efficient acceleration of cosmic rays at the shock, significantly enhanced mixing is not expected in Type Ia supernova remnants.

  7. Docosahexaenoic acid supplementation decreases remnant-like particle-cholesterol and increases omega-3 index in hypertriglyceridemic men1-3.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Plasma remnant-like particle-cholesterol (RLP-C) and RBC omega-3 index are novel risk factors for cardiovascular disease. Effects of docosahexaenoic acid (DHA) supplementation on these risk factors in hypertriglyceridemic men have not been studied. Objective: We determined effects of DHA...

  8. A Novel Adhesion Index for Verifying the Extent of Adhesion for the Extensor Digitorum Communis in Patients with Metacarpal Fractures.

    PubMed

    Lai, Ting-Yu; Chen, Hsiao-I; Shih, Cho-Chiang; Kuo, Li-Chieh; Hsu, Hsiu-Yun; Huang, Chih-Chung

    2016-01-01

    This study aims to determine if the relative displacement between the extensor digitorum communis (EDC) tendon and its surrounding tissues can be used as an adhesion index (AI) for assessing adhesion in metacarpal fractures by comparing two clinical measures, namely single-digit-force and extensor lag (i.e., the difference between passive extension and full active extension). The Fisher-Tippett block-matching method and a Kalman-filter algorithm were used to determine the relative displacements in 39 healthy subjects and 8 patients with metacarpal fractures. A goniometer was used to measure the extensor lag, and a force sensor was used to measure the single-digit-force. Measurements were obtained twice for each patient to evaluate the performance of the AI in assessing the progress of rehabilitation. The Pearson correlation coefficient was calculated to quantify the various correlations between the AI, extensor lag, and single-digit-force. The results showed strong correlations between the AI and the extensor lag, the AI and the single-digit-force, and the extensor lag and the single-digit-force (r = 0.718, -0.849, and -0.741; P = 0.002, P < 0.001, and P = 0.001, respectively). The AI in the patients gradually decreased after continuous rehabilitation, but remained higher than that of healthy participants. PMID:27492808

  9. A Novel Adhesion Index for Verifying the Extent of Adhesion for the Extensor Digitorum Communis in Patients with Metacarpal Fractures

    PubMed Central

    Lai, Ting-Yu; Chen, Hsiao-I; Shih, Cho-Chiang; Kuo, Li-Chieh; Hsu, Hsiu-Yun; Huang, Chih-Chung

    2016-01-01

    This study aims to determine if the relative displacement between the extensor digitorum communis (EDC) tendon and its surrounding tissues can be used as an adhesion index (AI) for assessing adhesion in metacarpal fractures by comparing two clinical measures, namely single-digit-force and extensor lag (i.e., the difference between passive extension and full active extension). The Fisher–Tippett block-matching method and a Kalman-filter algorithm were used to determine the relative displacements in 39 healthy subjects and 8 patients with metacarpal fractures. A goniometer was used to measure the extensor lag, and a force sensor was used to measure the single-digit-force. Measurements were obtained twice for each patient to evaluate the performance of the AI in assessing the progress of rehabilitation. The Pearson correlation coefficient was calculated to quantify the various correlations between the AI, extensor lag, and single-digit-force. The results showed strong correlations between the AI and the extensor lag, the AI and the single-digit-force, and the extensor lag and the single-digit-force (r = 0.718, −0.849, and −0.741; P = 0.002, P < 0.001, and P = 0.001, respectively). The AI in the patients gradually decreased after continuous rehabilitation, but remained higher than that of healthy participants. PMID:27492808

  10. Adhesion

    MedlinePlus

    ... as the shoulder Eyes Inside the abdomen or pelvis Adhesions can become larger or tighter over time. ... Other causes of adhesions in the abdomen or pelvis include: Appendicitis , most often when the appendix breaks ...

  11. Cilostazol prevents remnant lipoprotein particle-induced monocyte adhesion to endothelial cells by suppression of adhesion molecules and monocyte chemoattractant protein-1 expression via lectin-like receptor for oxidized low-density lipoprotein receptor activation.

    PubMed

    Park, So Youn; Lee, Jeong Hyun; Kim, Yong Ki; Kim, Chi Dae; Rhim, Byung Yong; Lee, Won Suk; Hong, Ki Whan

    2005-03-01

    This study shows cilostazol effect to prevent remnant lipoprotein particle (RLP)-induced monocyte adhesion to human umbilical vein endothelial cells (HUVECs). Upon incubation of HUVECs with RLP (50 microg/ml), adherent monocytes significantly increased by 3.3-fold with increased cell surface expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1, E-selectin, and monocyte chemoattractant protein-1 (MCP-1). Cilostazol ( approximately 1-100 microM) concentration dependently repressed these variables as did (E)3-[(4-t-butylphenyl)sulfonyl]-2-propenenitrile (BAY 11-7085) (10 microM), a specific nuclear factor-kappaB (NF-kappaB) inhibitor. Cilostazol effects were significantly antagonized by iberiotoxin (1 microM), a maxi-K channel blocker. RLP significantly increased expression of lectin-like receptor for oxidized low-density lipoprotein (LDL) (LOX-1) receptor protein. Upon transfection with antisense LOX-1 oligodeoxynucleotide (As-LOX-1), LOX-1 receptor expression was reduced, whereas HUVECs with sense LOX-1 oligodeoxynucleotide did express high LOX-1 receptor. RLP-stimulated superoxide and tumor necrosis factor-alpha levels were significantly lowered with decreased expression of VCAM-1 and MCP-1 by transfection with As-LOX-1 as did polyinosinic acid (10 microg/ml, a LOX-1 receptor inhibitor). RLP significantly degraded inhibitory kappaBalpha in the cytoplasm and activated nuclear factor-kappaB (NF-kappaB) p65 in the nucleus of HUVECs with increased luciferase activity of NF-kappaB, all of which were reversed by cilostazol (10 microM), BAY 11-7085, and polyinosinic acid. Together, cilostazol suppresses RLP-stimulated increased monocyte adhesion to HUVECs by suppression of LOX-1 receptor-coupled NF-kappaB-dependent nuclear transcription via mediation of the maxi-K channel opening.

  12. Adhesions

    MedlinePlus

    ... surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They might connect the loops of the intestines to each other, to nearby ... can occur anywhere in the body. But they often form after surgery on the ...

  13. Supernova remnants

    NASA Astrophysics Data System (ADS)

    Decourchelle, A.

    2016-06-01

    Supernova remnants result from the explosion of a star and keep trace, in their young ejecta-dominated phase, both of the explosion mechanism and to a lesser extent of the nature of the progenitor. They inject a large amount of energy into their surroundings, which impacts significantly the interstellar medium and to a larger extent the working of the galaxy by distributing heavy elements, heating to tens of million degrees large fractions of gas, accelerating high-energy particles, generating turbulence and amplification of the magnetic field. I will review the observational results on supernova remnants and their related scientific issues before suggesting directions for future ambitious XMM-Newton observations.

  14. Shear bond strength of orthodontic color-change adhesives with different light-curing times

    PubMed Central

    Bayani, Shahin; Ghassemi, Amirreza; Manafi, Safa; Delavarian, Mohadeseh

    2015-01-01

    Background: The purpose of this study was to evaluate the effect of light-curing time on the shear bond strength (SBS) of two orthodontic color-change adhesives (CCAs). Materials and Methods: A total of 72 extracted premolars were randomly assigned into 6 groups of 12 teeth each. Subsequent to primer application, a metal bracket was bonded to the buccal surface using an orthodontic adhesive. Two CCAs (Greengloo and Transbond Plus) were tested and one conventional light-cured adhesive (Resilience) served as control. For each adhesive, the specimens were light-cured for two different times of 20 and 40 s. All the specimens underwent mechanical testing using a universal testing machine to measure the SBS. Adhesive remnant index (ARI) was used to assess the remnant adhesive material on the tooth surface. All statistical analyses were performed using SPSS software. The significance level for all statistical tests was set at P ≤ 0.05. Results: The SBSs of the tested groups were in the range of 14.05-31.25 MPa. Greengloo adhesive showed the highest SBS values when light-cured for 40 s, and Transbond Plus adhesive showed the lowest values when light-cured for 20 s. ARI scores of Transbond Plus adhesive were significantly higher than those of controls, while other differences in ARI values were not significant. Conclusion: Within the limitations of his study, decreasing the light-curing time from 40 to 20 s decreased the SBS of the tested adhesives; however, this decline in SBS was statistically significant only in Transbond Plus adhesive PMID:26005468

  15. Remnant field detector

    DOEpatents

    Visser, Age T.

    1988-05-03

    A method apparatus for qualitatively detecting remnant magnetic fields in matched pairs of magnet cores. Equal magnitude and oppositely oriented magnetic flux is induced in the magnet cores by oppositely wound primary windings and current source. Identically wound secondary windings generate output voltages in response to the induced flux. The output voltages generated should be of equal magnitude and opposite polarity if there is no remnant field in the cores. The output voltages will be unequal which is detected if either core has a remnant field.

  16. Remnant field detector

    DOEpatents

    Visser, Age T.

    1988-01-01

    A method apparatus for qualitatively detecting remnant magnetic fields in matched pairs of magnet cores. Equal magnitude and oppositely oriented magnetic flux is induced in the magnet cores by oppositely wound primary windings and current source. Identically wound secondary windings generate output voltages in response to the induced flux. The output voltages generated should be of equal magnitude and opposite polarity if there is no remnant field in the cores. The output voltages will be unequal which is detected if either core has a remnant field.

  17. Evaluation of Self-Etching Adhesive and Er:YAG Laser Conditioning on the Shear Bond Strength of Orthodontic Brackets

    PubMed Central

    Contreras-Bulnes, Rosalía; Scougall-Vilchis, Rogelio J.; Rodríguez-Vilchis, Laura E.; Centeno-Pedraza, Claudia; Olea-Mejía, Oscar F.; Alcántara-Galena, María del Carmen Z.

    2013-01-01

    The purpose of this study was to evaluate the shear bond strength, the adhesive remnant index scores, and etch surface of teeth prepared for orthodontic bracket bonding with self-etching primer and Er:YAG laser conditioning. One hundred and twenty bovine incisors were randomly divided into four groups. In Group I (Control), the teeth were conditioned with 35% phosphoric acid for 15 seconds. In Group II the teeth were conditioned with Transbond Plus SEP (5 sec); III and IV were irradiated with the Er:YAG 150 mJ (11.0 J/cm2), 150 mJ (19.1 J/cm2), respectively, at 7–12 Hz with water spray. After surface preparation, upper central incisor stainless steel brackets were bonded with Transbond Plus Color Change Adhesive. The teeth were stored in water at 37°C for 24 hours and shear bond strengths were measured, and adhesive remnant index (ARI) was determined. The conditioned surface was observed under a scanning electron microscope. One-way ANOVA and chi-square test were used. Group I showed the significantly highest values of bond strength with a mean value of 8.2 megapascals (MPa). The lesser amount of adhesive remnant was found in Group III. The results of this study suggest that Er:YAG laser irradiation could not be an option for enamel conditioning. PMID:24228014

  18. Remnant cystic duct adenocarcinoma presenting as gastric outlet obstruction

    PubMed Central

    Lo, Samuel Tsoon Wuan; Cheng, Yue; Cheung, Frances; Tang, Chung Ngai

    2016-01-01

    Only a few case reports of remnant cystic duct carcinoma exist. The presented case of remnant cystic duct carcinoma with invasion to pylorus and bulbus of duodenum leading to gastric outlet obstruction was the first of its kind. We reviewed all cases of remnant cystic duct carcinoma that we found in the literature and summarized its definition, presentation, extent of invasion and clinical outcome after operation. The diagnosis can be difficult due to the rarity of disease, locally advanced nature of disease and distorted postoperative anatomy. A high index of suspicion can increase the likelihood of a preoperative diagnosis. PMID:27154747

  19. Remnants, fuzzballs or wormholes?

    NASA Astrophysics Data System (ADS)

    Mathur, Samir D.

    2014-11-01

    The black hole information paradox has caused enormous confusion over four decades. But in recent years, the theorem of quantum strong-subadditivity has sorted out the possible resolutions into three sharp categories: (i) No new physics at r ≫ lp; this necessarily implies remnants/information loss. A realization of remnants is given by a baby universe attached near r 0. (ii) Violation of the "no-hair" theorem by nontrivial effects at the horizon r M. This possibility is realized by fuzzballs in string theory, and gives unitary evaporation. (iii) Having the vacuum at the horizon, but requiring that Hawking quanta at r M3 be somehow identified with degrees of freedom inside the black hole. A model for this "extreme nonlocality" is realized by conjecturing that wormholes connect the radiation quanta to the hole.

  20. Sedimentary Rock Remnants

    NASA Technical Reports Server (NTRS)

    2005-01-01

    29 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows knobs of remnant, wind-eroded, layered sedimentary rock that once completely covered the floor of a crater located west of the Sinus Meridiani region of Mars. Sedimentary rock outcrops are common throughout the Sinus Meridiani region and its surrounding cratered terrain.

    Location near: 2.2oN, 7.9oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  1. What Shapes Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Lopez, Laura A.

    2014-01-01

    Evidence has mounted that Type Ia and core-collapse (CC) supernovae (SNe) can have substantial deviations from spherical symmetry; one such piece of evidence is the complex morphologies of supernova remnants (SNRs). However, the relative role of the explosion geometry and the environment in shaping SNRs remains an outstanding question. Recently, we have developed techniques to quantify the morphologies of SNRs, and we have applied these methods to the extensive X-ray and infrared archival images available of Milky Way and Magellanic Cloud SNRs. In this proceeding, we highlight some results from these studies, with particular emphasis on SNR asymmetries and whether they arise from ``nature'' or ``nurture''.

  2. Shear Bond Strength of Orthodontic Brackets Fixed with Remineralizing Adhesive Systems after Simulating One Year of Orthodontic Treatment.

    PubMed

    Bezerra, Gisele Lima; Torres, Carlos Rocha Gomes; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique; Kuga, Milton Carlos; Bandeca, Matheus Coelho; Firoozmand, Leily Macedo

    2015-01-01

    The objective of this study is to assess, in vitro, the shear bond strength of orthodontic brackets fixed with remineralizing adhesive systems submitted to thermomechanical cycling, simulating one year of orthodontic treatment. Sixty-four bovine incisor teeth were randomly divided into 4 experimental groups (n = 16): XT: Transbond XT, QC: Quick Cure, OL: Ortholite Color, and SEP: Transbond Plus Self-Etching Primer. The samples were submitted to thermomechanical cycling simulating one year of orthodontic treatment. Shear bond strength tests were carried out using a universal testing machine with a load cell of 50 KgF at 0.5 mm/minute. The samples were examined with a stereomicroscope and a scanning electron microscope (SEM) in order to analyze enamel surface and Adhesive Remnant Index (ARI). Kruskal-Wallis and Mann-Whitney (with Bonferroni correction) tests showed a significant difference between the studied groups (p < 0.05). Groups XT, QC, and SEP presented the highest values of adhesive resistance and no statistical differences were found between them. The highest frequency of failures between enamel and adhesive was observed in groups XT, QC, and OL. Quick Cure (QC) remineralizing adhesive system presented average adhesive resistance values similar to conventional (XT) and self-etching (SEP) adhesives, while remineralizing system (OL) provided the lowest values of adhesive resistance. PMID:26380371

  3. Shear Bond Strength of Orthodontic Brackets Fixed with Remineralizing Adhesive Systems after Simulating One Year of Orthodontic Treatment

    PubMed Central

    Bezerra, Gisele Lima; Torres, Carlos Rocha Gomes; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique; Kuga, Milton Carlos; Bandeca, Matheus Coelho; Firoozmand, Leily Macedo

    2015-01-01

    The objective of this study is to assess, in vitro, the shear bond strength of orthodontic brackets fixed with remineralizing adhesive systems submitted to thermomechanical cycling, simulating one year of orthodontic treatment. Sixty-four bovine incisor teeth were randomly divided into 4 experimental groups (n = 16): XT: Transbond XT, QC: Quick Cure, OL: Ortholite Color, and SEP: Transbond Plus Self-Etching Primer. The samples were submitted to thermomechanical cycling simulating one year of orthodontic treatment. Shear bond strength tests were carried out using a universal testing machine with a load cell of 50 KgF at 0.5 mm/minute. The samples were examined with a stereomicroscope and a scanning electron microscope (SEM) in order to analyze enamel surface and Adhesive Remnant Index (ARI). Kruskal-Wallis and Mann-Whitney (with Bonferroni correction) tests showed a significant difference between the studied groups (p < 0.05). Groups XT, QC, and SEP presented the highest values of adhesive resistance and no statistical differences were found between them. The highest frequency of failures between enamel and adhesive was observed in groups XT, QC, and OL. Quick Cure (QC) remineralizing adhesive system presented average adhesive resistance values similar to conventional (XT) and self-etching (SEP) adhesives, while remineralizing system (OL) provided the lowest values of adhesive resistance. PMID:26380371

  4. Supernova Remnants And GLAST

    SciTech Connect

    Slane, Patrick; /Harvard-Smithsonian Ctr. Astrophys.

    2011-11-29

    It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the area of cosmic ray acceleration by SNRs, and discuss the contributions GLAST will bring to our understanding of this problem.

  5. PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS

    SciTech Connect

    Moriya, Takashi J.

    2012-05-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

  6. Progenitors of Recombining Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.

    2012-05-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

  7. Bond strength of a fluoride-releasing bracket adhesive. Experimental study.

    PubMed

    Graf, I; Breier, M; Huck, L; Schwarze, C W

    1999-01-01

    The aim of the study was to examine a new fluoride-releasing light-cured filling composite for its bonding and debonding qualities when used as a bracket adhesive. The material investigated was a hybrid composite containing a chemically modified fluoride apatite, which is claimed to provide the enamel with phosphate, calcium, and fluoride ions in the presence of an acid pH, recharging its resources of these ions through fluoride-containing toothpastes used in daily oral hygiene. Concurrently suitability as an enamel conditioner was tested in a new self-etching primer, which does not require water rinsing but is gently air dried instead. For comparison a conventional light-cure single-component adhesive was used together with 37% orthophosphoric acid. After application of the respective conditioners, mesh-backed metal brackets were bonded to 20 human premolars in each of the 2 adhesive groups and subjected to a shear test. Bond failure location was evaluated using the Adhesive Remnant Index (ARI). Average bond strength of the experimental bracket adhesive and the conventional etchant was 8.96 MPa. Conditioning with the self-etching primer led to a decrease of mean shear bond strength values to 6.55 MPa. Highest bond strength was determined in the control group (12.19 MPa). The bond strength results obtained in the shear test recommend the new material as a bracket adhesive to be used with orthophosphoric acid for etching. PMID:10028788

  8. HESS upper limits for Kepler's supernova remnant

    NASA Astrophysics Data System (ADS)

    Aharonian, F.; Akhperjanian, A. G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Behera, B.; Beilicke, M.; Benbow, W.; Berge, D.; Bernlöhr, K.; Boisson, C.; Bolz, O.; Borrel, V.; Braun, I.; Brion, E.; Brucker, J.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Carrigan, S.; Chadwick, P. M.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Cornils, R.; Costamante, L.; Dalton, M.; Degrange, B.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubois, F.; Dubus, G.; Dyks, J.; Egberts, K.; Emmanoulopoulos, D.; Espigat, P.; Farnier, C.; Feinstein, F.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gallant, Y. A.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Hadjichristidis, C.; Hauser, D.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jung, I.; Katarzyński, K.; Kendziorra, E.; Kerschhaggl, M.; Khélifi, B.; Keogh, D.; Komin, Nu.; Kosack, K.; Lamanna, G.; Latham, I. J.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Martin, J. M.; Martineau-Huynh, O.; Marcowith, A.; Masterson, C.; Maurin, D.; McComb, T. J. L.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nolan, S. J.; Ohm, S.; Olive, J.-P.; de Oña Wilhelmi, E.; Orford, K. J.; Osborne, J. L.; Ostrowski, M.; Panter, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Renaud, M.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Ruppel, J.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schröder, R.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sol, H.; Spangler, D.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Superina, G.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.

    2008-09-01

    Aims: Observations of Kepler's supernova remnant (G4.5+6.8) with the HESS telescope array in 2004 and 2005 with a total live time of 13 h are presented. Methods: Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. Results: No evidence for a very high energy (VHE: >100 GeV) gamma-ray signal from the direction of the remnant is found. An upper limit (99% confidence level) on the energy flux in the range 230 GeV{-}12.8 TeV of 8.6 × 10-13 erg cm-2 s-1 is obtained. Conclusions: In the context of an existing theoretical model for the remnant, the lack of a detectable gamma-ray flux implies a distance of at least 6.4 kpc. A corresponding upper limit for the density of the ambient matter of 0.7 cm-3 is derived. With this distance limit, and assuming a spectral index Γ = 2, the total energy in accelerated protons is limited to Ep < 8.6 × 1049 erg. In the synchrotron/inverse Compton framework, extrapolating the power law measured by RXTE between 10 and 20 keV down in energy, the predicted gamma-ray flux from inverse Compton scattering is below the measured upper limit for magnetic field values greater than 52 μ G.

  9. A multiwavelength study of the remnant of nova GK Persei

    NASA Astrophysics Data System (ADS)

    Anupama, G. C.; Kantharia, N. G.

    2005-05-01

    We present new observations of the nebular remnant of the old nova GK Persei 1901 in the optical using the Himalayan Chandra Telescope (HCT) and at low radio frequencies using the Giant Metrewave Radio Telescope (GMRT). The dimensions of the shell in the optical emission lines of [NII], [OIII] and [OII] are 108× 94 arcsec2, 104× 94 arcsec2 and 99× 87 arcsec2, respectively. The evolution of the nova remnant indicates shock interaction with the ambient medium, especially in the southwest quadrant. Application of a simple model for the shock and its evolution to determine the time dependence of the radius of the shell in the southwest quadrant indicates that the shell is now expanding into an ambient medium that has a density of 0.12 cm-3, compared to the density of the ambient medium of 0.8 cm-3 ahead of the shock in 1987. There are indications of a recent interaction of the nova remnant with the ambient medium in the northeast quadrant. There is a distinct flattening of the shell, as well as an increase in the number and brightness of the knots in the region. The brightest optical knots in this region are also detected in the radio images. The nova remnant of GK Per is detected at all the observed radio frequencies and is of a similar extent to the optical remnant. Putting together our radio observations with VLA archival data on GK Per from 1997, we obtain three interesting results: 1. the spectrum above 1.4 GHz follows a power law with an index -0.7 (S∝ να) and below 1.4 GHz follows a power law with an index ˜ -0.85. This could be due to the presence of at least two populations of electrons dominating the global emission at different frequencies; 2. we record an annual secular decrease of 2.1% in the flux density of the nova remnant at 1.4 and 4.9 GHz between 1984 and 1997 which has left the spectral index unchanged at -0.7. No such decrease is observed in the flux densities below 1 GHz; 3. we record an increase in the flux density at 0.33 GHz compared to

  10. Remnants of Lost Geology

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    In eastern Arabia Terra, remnants of a once vast layered terrain are evident as isolated buttes, mesas, and deeply-filled craters. The origin of the presumed sediments that created the layers is unknown, but those same sediments, now eroded, may be the source of the thick mantle of dust that covers much of Arabia Terra today.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 20.5, Longitude 50 East (310 West). 19 meter/pixel resolution.

  11. Thermal Radiation of Supernova Remnants in Radio Domain

    NASA Astrophysics Data System (ADS)

    Onić, Dušan

    The evolution of supernova remnants is linked to the propagation of a collisionless shock wave, formed during the initial expansion of high-velocity supernova ejecta through the interstellar environment. Theoretical studies of shock waves are very important for the analysis of supernova remnants, as well as processes in the interstellar medium in general. In this doctoral dissertation, some theoretical results based on the magnetohydrodynamical theory of shock waves are presented, with special emphasis on ideal radiative magnetohydrodynamics for the optically thick case. Particularly, solutions for the case when jump in adiabatic index and/or ratio of gas to total pressure is allowed, are discussed. The main hypothesis of this dissertation is that thermal bremsstrahlung radiation at radio continuum frequencies can provide a significant contribution in the case of several Galactic supernova remnants. This hypothesis can give a natural explanation for nearly concave up radio continuum spectra of several Galactic supernova remnants that are expanding in the environment with higher than average density. In this context, it is important to identify the existence of the possible indicators of ensemble of thermal electrons at sufficiently low temperatures and sufficiently high densities so that the thermal bremsstrahlung radiation linked to a particular remnant could be observed at radio continuum frequencies (vicinity, interaction or expansion through the molecular cloud, presence of the cooled thermal X-ray electrons during the post Sedov-Taylor phases, detection of low-frequency turnovers associated with thermal absorption linked to the remnant, detection in Halpha, identification of radio recombination lines linked to the remnant, etc). The significant presence of thermal component could theoretically explain radio-spectral indices less than 0.5 measured for several evolutionary older supernova remnants, (mainly of mixed-morphology class) that expand in the high

  12. Effects of long-term repeated topical fluoride applications and adhesion promoter on shear bond strengths of orthodontic brackets

    PubMed Central

    Endo, Toshiya; Ishida, Rieko; Komatsuzaki, Akira; Sanpei, Shinya; Tanaka, Satoshi; Sekimoto, Tsuneo

    2014-01-01

    Objective: The purpose of this study was to assess the effects of long-term repeated topical application of fluoride before bonding and an adhesion promoter on the bond strength of orthodontic brackets. Materials and Methods: A total of 76 bovine incisors were collected and divided equally into four groups. In group 1, the brackets were bonded without topical fluoride application or adhesion promoter. In group 2, before bonding, the adhesion promoter was applied to nonfluoridated enamel. In group 3, the brackets were bonded without the application of the adhesion promoter to enamel, which had undergone long-term repeated topical fluoride treatments. Teeth in group 4 received the long-term repeated topical applications of fluoride, and the brackets were bonded using the adhesion promoter. All the brackets were bonded using BeautyOrtho Bond self-etching adhesive. The shear bond strength was measured and the bond failure modes were evaluated with the use of the adhesive remnant index (ARI) after debonding. Results: The mean shear bond strength was significantly lower in group 3 than in groups 1, 2, and 4, and there were no significant differences between the groups except for group 3. There were significant differences in the distribution of ARI scores between groups 2 and 3, and between groups 3 and 4. Conclusions: The adhesion promoter can recover the bond strength reduced by the long-term repeated topical applications of fluoride to the prefluoridation level and had a significantly great amount of adhesives left on either fluoridated or nonfluoridated enamel. PMID:25512720

  13. The Supernova Remnant CTA 1

    NASA Technical Reports Server (NTRS)

    Seward, Frederick D.

    1996-01-01

    The supernova remnants G327.1-1.1 and G327.4+0.4 (Kes 27) are located 1.5 deg apart in the constellation Norma. In 1980, Einstein IPC observations discovered that both were irregular filled-center X-ray sources with possible point sources superposed. This paper describes new ROSAT position sensitive proportional counter (PSPC) observations which both map the diffuse structure and clearly show several unresolved sources in each field. Both remnants have bright emitting regions inside the limb which might indicate the presence of high energy electrons accelerated by a pulsar. The interior region is more prominent in G327.1-1.1 than in Kes 27. The spectra are relatively strongly absorbed, as expected from distant remnants close to the galactic plane. Comparison of the X-ray and radio maps of each remnant allows us to attribute some emission to a shell and some to the interior. With this information, a blast-wave model is used to derive approximate ages and energy release. Indications are that the Kes 27 supernova deposited approximately 10(exp 51) ergs in the surrounding medium. The G327.1-1.1 event probably deposited a factor of 3-10 less.

  14. Constraints on black hole remnants

    SciTech Connect

    Giddings, S.B. )

    1994-01-15

    One possible fate of information lost to black holes is its preservation in black hole remnants. It is argued that a type of effective field theory describes such remnants (generically referred to as informons). The general structure of such a theory is investigated and the infinite pair production problem is revisited. A toy model for remnants clarifies some of the basic issues; in particular, infinite remnant production is not suppressed simply by the large internal volumes as proposed in cornucopion scenarios. Criteria for avoiding infinite production are stated in terms of couplings in the effective theory. Such instabilities remain a problem barring what would be described in that theory as a strong coupling conspiracy. The relation to Euclidean calculations of cornucopion production is sketched, and potential flaws in that analysis are outlined. However, it is quite plausible that pair production of ordinary black holes (e.g., Reissner-Noerdstrom or others) is suppressed due to strong effective couplings. It also remains an open possibility that a microsopic dynamics can be found yielding an appropriate strongly coupled effective theory of neutral informons without infinite pair production.

  15. Einstein Observations of Galactic supernova remnants

    NASA Technical Reports Server (NTRS)

    Seward, Frederick D.

    1990-01-01

    This paper summarizes the observations of Galactic supernova remnants with the imaging detectors of the Einstein Observatory. X-ray surface brightness contours of 47 remnants are shown together with gray-scale pictures. Count rates for these remnants have been derived and are listed for the HRI, IPC, and MPC detectors.

  16. Influence of Adhesives and Methods of Enamel Pretreatment on the Shear Bond Strength of Orthodontic Brackets

    PubMed Central

    Jurišić, Sanja; Jurišić, Gordan

    2015-01-01

    Aim The objective of present study was to examine influence of adhesives and methods of enamel pretreatment on the shear bond strength (SBS) of orthodontic brackets. The adhesives used were resin-reinforced glass ionomer cements-GIC (Fuji Ortho LC) and composite resin (Transbond XT). Material and Methods The experimental sample consisted of 80 extracted human first premolars. The sample was divided into four equal groups, and the metal brackets were bonded with different enamel pretreatments by using two adhesives: group A-10% polyacrylic acid; Fuji Ortho LC, group B–37% phosphoric acid; Fuji Ortho LC, group C–self etching primer; Transbond XT, group D–37% phosphoric acid, primer; Transbond XT. SBS of brackets was measured. After debonding of brackets, the adhesive remnant index (ARI) was evaluated. Results After the statistical analysis of the collected data was performed (ANOVA; Sheffe post-hoc test), the results showed that significantly lower SBS of the group B was found in relation to the groups C (p=0.031) and D (p=0.026). The results of ARI were similar in all testing groups and it was not possible to determine any statistically significant difference of the ARI (Chi- square test) between all four experimental groups. Conclusion The conclusion is that the use of composite resins material with appropriate enamel pretreatment according to manufacturer’s recommendation is the “gold standard” for brackets bonding for fixed orthodontic appliances. PMID:27688410

  17. Influence of Adhesives and Methods of Enamel Pretreatment on the Shear Bond Strength of Orthodontic Brackets

    PubMed Central

    Jurišić, Sanja; Jurišić, Gordan

    2015-01-01

    Aim The objective of present study was to examine influence of adhesives and methods of enamel pretreatment on the shear bond strength (SBS) of orthodontic brackets. The adhesives used were resin-reinforced glass ionomer cements-GIC (Fuji Ortho LC) and composite resin (Transbond XT). Material and Methods The experimental sample consisted of 80 extracted human first premolars. The sample was divided into four equal groups, and the metal brackets were bonded with different enamel pretreatments by using two adhesives: group A-10% polyacrylic acid; Fuji Ortho LC, group B–37% phosphoric acid; Fuji Ortho LC, group C–self etching primer; Transbond XT, group D–37% phosphoric acid, primer; Transbond XT. SBS of brackets was measured. After debonding of brackets, the adhesive remnant index (ARI) was evaluated. Results After the statistical analysis of the collected data was performed (ANOVA; Sheffe post-hoc test), the results showed that significantly lower SBS of the group B was found in relation to the groups C (p=0.031) and D (p=0.026). The results of ARI were similar in all testing groups and it was not possible to determine any statistically significant difference of the ARI (Chi- square test) between all four experimental groups. Conclusion The conclusion is that the use of composite resins material with appropriate enamel pretreatment according to manufacturer’s recommendation is the “gold standard” for brackets bonding for fixed orthodontic appliances.

  18. X-Ray Measured Dynamics of Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Petre, Robert; Hughes, John; Hwang, Una; Yamaguchi, Hiroya; Hayato, Asami; Mori, Koji; Tsunemi, Hiroshi

    2010-01-01

    We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of [approx]0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of [less, similar]0.2 cm-3.

  19. HI Absorption in Merger Remnants

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Veileux, Sylvain; Baker, Andrew J.

    2012-01-01

    It has been proposed that ultraluminous infrared galaxies (ULIRGs) pass through a luminous starburst phase, followed by a dust-enshrouded AGN phase, and finally evolve into optically bright "naked" quasars once they shed their gas/dust reservoirs through powerful wind events. We present the results of our recent 21- cm HI survey of 21 merger remnants with the Green Bank Telescope. These remnants were selected from the QUEST (Quasar/ULIRG Evolution Study) sample of ULIRGs and PG quasars; our targets are all bolometrically dominated by AGN and sample all phases of the proposed ULIRG -> IR-excess quasar -> optical quasar sequence. We explore whether there is an evolutionary connection between ULIRGs and quasars by looking for the occurrence of HI absorption tracing neutral gas outflows; our results will allow us to identify where along the sequence the majority of a merger's gas reservoir is expelled.

  20. Radio emision from supernova remnants

    NASA Astrophysics Data System (ADS)

    Dubner, G.

    2016-06-01

    The vast majority of supernova remnants (SNRs) in our Galaxy and nearby galaxies have been discovered through radio observations, and only a very small number of the SNRs catalogued in the Milky Way have not been detected in the radio band, or are poorly defined by current radio observations. The study of the radio emission from SNRs is an excellent tool to investigate morphological characteristics, marking the location of shock fronts and contact discontinuities; the presence, orientation and intensity of the magnetic field; the energy spectrum of the emitting particles; and the dynamical consequences of the interaction with the circumstellar and interstellar medium. I will review the present knowledge of different important aspects of radio remnants and their impact on the interstellar gas. Also, new radio studies of the Crab Nebula carried out with the Karl Jansky Very Large Array (JVLA) at 3 GHz and with ALMA at 100 GHz, will be presented.

  1. Effects of adhesion promoter on orthodontic bonding in fluorosed teeth: A scanning electron microscopy study

    PubMed Central

    Gaur, Aditi; Maheshwari, Sandhya; Verma, Sanjeev Kumar; Tariq, Mohd.

    2016-01-01

    Introduction: The objectives of the present study were to elucidate the effects of fluorosis in orthodontic bonding and to evaluate the efficiency of an adhesion promoter (Assure Universal Bonding Resin) in bonding to fluorosed teeth. Materials and Methods: Extracted premolars were divided into two groups on the basis of Thylstrup and Fejerskov Index. Ten samples from each group were etched and evaluated for etching patterns using scanning electron microscope (SEM). The remaining samples were subdivided into four groups of 20 each on the basis of adhesives used: IA, IIA - Transbond XT and IB, IIB - Transbond XT plus Assure Universal Bonding Resin. Shear bond strength (SBS) was measured after 24 h using the universal testing machine. Adhesive remnant index (ARI) scores were recorded using SEM. Statistical analysis was conducted using a two-way analysis of variance, and Tukey's post hoc test was performed on SBS and ARI scores. Results: Similar etching patterns were observed in both fluorosed and nonfluorosed teeth. No significant differences were found in the SBS values observed in both groups (8.66 ± 3.19 vs. 8.53 ± 3.44, P = 1.000). Increase in SBS was observed when Assure Universal Bonding Resin was used. Higher ARI scores were observed when adhesion promoter was used for bonding. Conclusions: Mild-moderately fluorosed teeth etch in a manner similar to the nonfluorosed teeth. Similar bond strengths were achieved in fluorosed and nonfluorosed teeth when conventional composite was used. Use of adhesion promoter increases the bond strengths in both groups of teeth. PMID:27556020

  2. New supernova remnant results from radio surveys

    NASA Astrophysics Data System (ADS)

    Helfand, D. J.

    Our knowledge of the Galactic supernova remnant population is woefully incomplete A total of 231 remnants appear in the latest catalog Green 2004 whereas we expect the total population to be between 500 and 1000 Helfand et al 1989 The current discovery rate of new remnants has averaged about four per year over the past two decades In recent years a number of new Galactic plane radio surveys have been undertaken which offer the possibility of significantly increasing this discovery rate For example the VLA MAGPIS survey Helfand et al 2006 has identified fifty new remnant candidates in a 27-degree swath of Galactic longitude Unsurprisingly this high-resolution survey finds many more small-diameter remnants than past single-dish observations increasing by seven-fold the number of remnants with diameters less than 5 arcmin in this region of the Galaxy Brogan et al report 90 cm observations in this region identifying up to 35 new remnants I will review all published results on new radio remnants highlighting the impact of these discoveries on our understanding of the remnant population and noting the value of observations from the mid-infrared to TeV gamma rays in defining the Galaxy s remnant population This work is supported in part by grant AST 05-07598 from the National Science Foundation

  3. Radio emission from supernova remnants

    NASA Astrophysics Data System (ADS)

    Dubner, Gloria; Giacani, Elsa

    2015-09-01

    The explosion of a supernova releases almost instantaneously about 10^{51} ergs of mechanic energy, changing irreversibly the physical and chemical properties of large regions in the galaxies. The stellar ejecta, the nebula resulting from the powerful shock waves, and sometimes a compact stellar remnant, constitute a supernova remnant (SNR). They can radiate their energy across the whole electromagnetic spectrum, but the great majority are radio sources. Almost 70 years after the first detection of radio emission coming from an SNR, great progress has been achieved in the comprehension of their physical characteristics and evolution. We review the present knowledge of different aspects of radio remnants, focusing on sources of the Milky Way and the Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief overview of theoretical background, analyze morphology and polarization properties, and review and critically discuss different methods applied to determine the radio spectrum and distances. The consequences of the interaction between the SNR shocks and the surrounding medium are examined, including the question of whether SNRs can trigger the formation of new stars. Cases of multispectral comparison are presented. A section is devoted to reviewing recent results of radio SNRs in the Magellanic Clouds, with particular emphasis on the radio properties of SN 1987A, an ideal laboratory to investigate dynamical evolution of an SNR in near real time. The review concludes with a summary of issues on radio SNRs that deserve further study, and analysis of the prospects for future research with the latest-generation radio telescopes.

  4. 16 CFR 303.13 - Sale of remnants and products made of remnants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... ACTS OF CONGRESS RULES AND REGULATIONS UNDER THE TEXTILE FIBER PRODUCTS IDENTIFICATION ACT § 303.13... “remnants of undetermined fiber content.” (3) Where textile fiber products are made of such remnants,...

  5. Recent progress on young Galactic supernova remnants

    NASA Astrophysics Data System (ADS)

    Williams, Brian J.

    2016-06-01

    I will review progress in the past few years on several young (less than a few thousand years old) supernova remnants within the Milky Way galaxy and the Magellanic Clouds. I will focus on objects like Tycho, Kepler, 3C 397, W49B, and Cas A. I will discuss not only what has been learned about particular remnants, but also what these remnants can tell us about their pre-supernova progenitor systems. I will also show areas in which newly launched and upcoming observatories, such as Hitomi (Astro-H) and JWST can contribute to the study of supernova remnants.

  6. Supernova Remnants in High Definition

    NASA Astrophysics Data System (ADS)

    Slane, Patrick; Badenes, Carles; Freyer, Chris; Hughes, Jack; Lee, Herman Shiu-Hang; Lopez, Laura; Patnaude, Daniel; Reynolds, Steve; Temim, Tea; Williams, Brian; Wongwathanarat, Annop; Yamaguchi, Hiroya

    2015-10-01

    As the observable products of explosive stellar death, supernova remnants reveal some of the most direct information on the physics of the explosions, the properties of the progenitor systems, and the demographics of compact objects formed in the supernova events. High sensitivity X-ray observations have allowed us to probe the properties of the shocked plasma, providing constraints on abundances and ionization states that connect directly progenitor masses and metallicities, the nature of the explosions (core-collapse vs. thermonuclear), and the physics of shock heating and particle acceleration in fast shocks. Studies of SNRs in the Magellanic Clouds have provided information on source demographics in a low metallicity environment, and deep searches for point sources in Galactic SNRs imply that many remnants contain rapidly cooling neutron stars or black holes. Based on Chandra observations, we know that crucial measurements required to advance our knowledge in these areas are possible only with much more sensitive observations at high angular resolution. From identifying the effects of particle acceleration on the post-shock gas in young SNRs like Tycho to obtaining spatially resolved spectra - and identifying compact objects - for young SNRs in the Magellanic Clouds, the capabilities of a facility like the X-ray Surveyor are required. Here I present a summary of recent advances brought about by spectral investigations of SNRs, and discuss particular examples of new advances that will be enabled by X-ray Surveyor capabilities.

  7. Pacinian Corpuscles in a Cervical Chondrocutaneous Remnant: A Case Report and Update of Pacinian Corpuscles.

    PubMed

    Feito, Jorge; Ramos-García, José L; Gago, Ángel; Cobo, Juan L; García-Suárez, Olivia; Junquera, Luis M; Vega, José A

    2016-03-01

    Cervical chondrocutaneous remnants are congenital, benign, and rare neck masses. We present here for the first time the immunohistochemical profile of Pacinian corpuscles present in cervical chondrocutaneous remnants, removed, and localized in the territory of the second branchial arch from a 5-year-old girl. We have performed immunohistochemistry to analyze these sensory corpuscles using a battery of antibodies including markers for each corpuscle constituent. The central axon was immunoreactive for neurofilaments, neuron-specific enolase, and neural cell adhesion molecule; the Schwann-related cells forming the inner core displayed immunoreactivity for S100 protein, vimentin, and neural cell adhesion molecule; the outer core and the capsule were positive for vimentin, epithelial membrane antigen, and glucose transporter 1. These results are discussed in topographical differences. Moreover, a brief update about the structure, protein composition, and development of Pacinian corpuscles was performed. PMID:26894776

  8. The Influence of No-Primer Adhesives and Anchor Pylons Bracket Bases on Shear Bond Strength of Orthodontic Brackets

    PubMed Central

    Sfondrini, Maria Francesca; Fraticelli, Danilo; Daina, Paola; Tamagnone, Alessandra; Gandini, Paola

    2013-01-01

    Objective. The aim of this study was to compare the shear bond strength (SBS) and adhesive remnant index (ARI) scores of no-primer adhesives tested with two different bracket bases. Materials and Methods. 120 bovine permanent mandibular incisors were divided into 6 groups of 20 specimens. Two brackets (ODP) with different bracket bases (anchor pylons and 80-gauge mesh) were bonded to the teeth using a conventional adhesive (Transbond XT) and two different no-primer adhesive (Ortho Cem; Heliosit) systems. Groups were tested using an instron universal testing machine. SBS values were recorded. ARI scores were measured. SEM microphotographs were taken to evaluate the pattern of bracket bases. Statistical analysis was performed. ANOVA and Tukey tests were carried out for SBS values, whereas a chi-squared test was applied for ARI scores. Results. Highest bond strength values were reported with Transbond XT (with both pad designs), Ortho Cem bonded on anchor pylons and Heliosit on 80-gauge mesh. A higher frequency of ARI score of “3” was reported for Transbond XT groups. Other groups showed a higher frequency of ARI score “2” and “1.” Conclusion. Transbond XT showed the highest shear bond strength values with both pad designs. PMID:23984339

  9. Shear bond strength of fibre-reinforced composite nets using two different adhesive systems.

    PubMed

    Sfondrini, Maria Francesca; Cacciafesta, Vittorio; Scribante, Andrea

    2011-02-01

    The purpose of this study was to evaluate the effect of two different adhesive systems (Tetric Flow and Transbond XT) in combination with fibre-reinforced composites (FRC) net (Ever Stick) on the shear bond strength (SBS) of orthodontic brackets. Eighty bovine permanent mandibular incisors were randomly divided into four equal groups. Stainless steel maxillary central incisor brackets with a 0.018 inch slot (DB Leone) were bonded to the teeth using the two different adhesive systems. Fifty per cent of the brackets were bonded without and 50 per cent with a FRC net under the bracket base. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for SBS. Analysis of variance indicated significant differences among the various groups. Brackets bonded with FRC nets under the base showed a significantly lower SBS than those bonded without nets (P < 0.05). Moreover, teeth bonded with Transbond XT showed a significantly higher SBS than the other groups. Additionally, significant differences in debond locations [adhesive remnant index (ARI) score] were found among the various groups. Transbond XT can successfully be used for direct bonding of FRC nets, thus improving their SBS values. PMID:20573712

  10. 27 CFR 19.359 - Remnants.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., Packaging, and Removal of Products § 19.359 Remnants. When at the end of a bottling run fewer bottles remain than the number necessary to fill a case, the remaining bottles may be placed in a case marked as a... remnant bottles may later be used to complete the filling of a case, or may be used for another...

  11. Searching for GRB Remnants in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Bhargavi, S. G.; Rhoads, J.; Perna, R.; Feldmeier, J.; Greiner, J.

    2004-09-01

    Gamma Ray Bursts (GRBs) are expected to leave behind GRB remnants, similar to how ``standard'' supernovae (SN) leave behind SN remnants. The identification of these remnants in our own and in nearby galaxies would allow a much closer look at GRB birth sites, and possibly lead to the discovery of the compact object left behind. It would also provide independent constraints on GRB rates and energetics. We have initiated an observational program (2002) to search for GRB remnants in nearby galaxies. The identification is based on specific line ratios, such as OIII/Hβ and HeII/Hβ. which are expected to be unusually high in case of GRB remnants according to the theoretical predictions of Perna et al. (2000). The observing strategies and preliminary studies from a test run at 2.34 m VBT as well as archival data from planetary nebulae surveys of spiral galaxies are discussed.

  12. ANTIPROTONS PRODUCED IN SUPERNOVA REMNANTS

    SciTech Connect

    Berezhko, E. G.; Ksenofontov, L. T.

    2014-08-20

    We present the energy spectrum of an antiproton cosmic ray (CR) component calculated on the basis of the nonlinear kinetic model of CR production in supernova remnants (SNRs). The model includes the reacceleration of antiprotons already existing in the interstellar medium as well as the creation of antiprotons in nuclear collisions of accelerated protons with gas nuclei and their subsequent acceleration by SNR shocks. It is shown that the production of antiprotons in SNRs produces a considerable effect in their resultant energy spectrum, making it essentially flatter above 10 GeV so that the spectrum at TeV energies increases by a factor of 5. The calculated antiproton spectrum is consistent with the PAMELA data, which correspond to energies below 100 GeV. As a consistency check, we have also calculated within the same model the energy spectra of secondary nuclei and show that the measured boron-to-carbon ratio is consistent with the significant SNR contribution.

  13. Featured Image: Modeling Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    This image shows a computer simulation of the hydrodynamics within a supernova remnant. The mixing between the outer layers (where color represents the log of density) is caused by turbulence from the Rayleigh-Taylor instability, an effect that arises when the expanding core gas of the supernova is accelerated into denser shell gas. The past standard for supernova-evolution simulations was to perform them in one dimension and then, in post-processing, manually smooth out regions that undergo Rayleigh-Taylor turbulence (an intrinsically multidimensional effect). But in a recent study, Paul Duffell (University of California, Berkeley) has explored how a 1D model could be used to reproduce the multidimensional dynamics that occur in turbulence from this instability. For more information, check out the paper below!CitationPaul C. Duffell 2016 ApJ 821 76. doi:10.3847/0004-637X/821/2/76

  14. Supernovae, young remnants, and nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Kirshner, R. P.

    1982-01-01

    Chemical abundance data from extragalactic supernovae and from supernova remnants (SNR) less than 1000 yrs old are employed to show that nuclear burning beyond helium synthesis actually occurs. Supernova (SN) are classified into types I or II, having no hydrogen lines or featuring hydrogen lines, respectively. The SN I's have been observed as having a preponderance of Fe lines, and emitting from a source at around 12,000 K with a center continuum of approximately 10 AU. Decay chains which could account for detected luminosities and spectra are presented, noting a good fit of Fe II spectrum with observed SN spectra. SNR pass through younger and older stages, going from the outpouring of material to diffusion in the interstellar medium. Expanding flocculi from young SNR show oxygen abundances as well as lines from sulfur, calcium, and argon, with a corresponding necessity of an explosive source of 15 solar masses.

  15. ANTIMATTER PRODUCTION IN SUPERNOVA REMNANTS

    SciTech Connect

    Kachelriess, M.; Ostapchenko, S.; Tomas, R.

    2011-06-01

    We calculate the energy spectra of cosmic rays (CRs) and their secondaries produced in a supernova remnant (SNR) taking into account the time dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusion coefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: the positron/electron ratio F{sub e}{sup +}/F{sub e}{sup +}{sub +e}{sup -} and the antiproton/proton ratio F{sub p-bar/}F{sub p-bar+p} are a few percent and few x 10{sup -5}, respectively. Moreover, the obtained positron/electron ratio decreases with energy, while the antiproton/proton ratio rises at most by a factor of two above 10 GeV.

  16. Evaluation of enamel damages following orthodontic bracket debonding in fluorosed teeth bonded with adhesion promoter

    PubMed Central

    Baherimoghadam, Tahreh; Akbarian, Sahar; Rasouli, Reza; Naseri, Navid

    2016-01-01

    Objective: To evaluate shear bond strength (SBS) of the orthodontic brackets bonded to fluorosed and nonfluorosed teeth using Light Bond with and without adhesion promoters and compare their enamel damages following debonding. Materials and Methods: In this study, 30 fluorosed (Thylstrup and Fejerskov Index = 4–5) and 30 nonfluorosed teeth were randomly distributed between two subgroups according to the bonding materials: Group 1, fluorosed teeth bonded with Light Bond; Group 2, fluorosed teeth bonded with adhesion promoters and Light Bond; Group 3, nonfluorosed teeth bonded with Light Bond; Group 4, nonfluorosed bonded with adhesion promoters and Light Bond. After bonding, the SBS of the brackets was tested with a universal testing machine. Stereomicroscopic evaluation was performed by unbiased stereology in all teeth to determine the amount of adhesive remnants and the number and length of enamel cracks before bonding and after debonding. The data were analyzed using two-way analysis of variance, Kruskal–Wallis, Wilcoxon Signed Rank, and Mann–Whitney test. Results: While fluorosis reduced the SBS of orthodontic bracket (P = 0.017), Enhance Locus Ceruleus LC significantly increased the SBS of the orthodontic bracket in fluorosed and nonfluorosed teeth (P = 0.039). Significant increasing in the number and length of enamel crack after debonding was found in all four groups. There were no significant differences in the length of enamel crack increased after debonding among four groups (P = 0.768) while increasing in the number of enamel cracks after debonding was significantly different among the four groups (P = 0.023). Teeth in Group 2 showed the highest enamel damages among four groups following debonding. Conclusion: Adhesion promoters could improve the bond strength of orthodontic brackets, but conservative debonding methods for decreasing enamel damages would be necessary. PMID:27095895

  17. FERMI LARGE AREA TELESCOPE DETECTION OF SUPERNOVA REMNANT RCW 86

    SciTech Connect

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-20

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ∼5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ∼ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  18. Fermi Large Area Telescope Detection of Supernova Remnant RCW 86

    NASA Astrophysics Data System (ADS)

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-01

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ~5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ~ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  19. Adhesive plasters

    DOEpatents

    Holcombe, Jr., Cressie E.; Swain, Ronald L.; Banker, John G.; Edwards, Charlene C.

    1978-01-01

    Adhesive plaster compositions are provided by treating particles of Y.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Gd.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 with dilute acid solutions. The resulting compositions have been found to spontaneously harden into rigid reticulated masses resembling plaster of Paris. Upon heating, the hardened material is decomposed into the oxide, yet retains the reticulated rigid structure.

  20. Progenitor's Signatures in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.

    2013-01-01

    The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisting of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and kinematics to show that the ejecta has likely interacted with dense circumstellar gas.

  1. Effect of acid etching on bond strength of nanoionomer as an orthodontic bonding adhesive

    PubMed Central

    Khan, Saba; Verma, Sanjeev K.; Maheshwari, Sandhya

    2015-01-01

    Aims: A new Resin Modified Glass Ionomer Cement known as nanoionomer containing nanofillers of fluoroaluminosilicate glass and nanofiller 'clusters' has been introduced. An in-vitro study aimed at evaluating shear bond strength (SBS) and adhesive remnant index (ARI) of nanoionomer under etching/unetched condition for use as an orthodontic bonding agent. Material and Methods: A total of 75 extracted premolars were used, which were divided into three equal groups of 25 each: 1-Conventional adhesive (Enlight Light Cure, SDS, Ormco, CA, USA) was used after and etching with 37% phosphoric acid for 30 s, followed by Ortho Solo application 2-nanoionomer (Ketac™ N100, 3M, ESPE, St. Paul, MN, USA) was used after etching with 37% phosphoric acid for 30 s 3-nanoionomer was used without etching. The SBS testing was performed using a digital universal testing machine (UTM-G-410B, Shanta Engineering). Evaluation of ARI was done using scanning electron microscopy. The SBS were compared using ANOVA with post-hoc Tukey test for intergroup comparisons and ARI scores were compared with Chi-square test. Results: ANOVA (SBS, F = 104.75) and Chi-square (ARI, Chi-square = 30.71) tests revealed significant differences between groups (P < 0.01). The mean (SD) SBS achieved with conventional light cure adhesive was significantly higher (P < 0.05) (10.59 ± 2.03 Mpa, 95% CI, 9.74-11.41) than the nanoionomer groups (unetched 4.13 ± 0.88 Mpa, 95% CI, 3.79-4.47 and etched 9.32 ± 1.87 Mpa, 95% CI, 8.58-10.06). However, nanoionomer with etching, registered SBS in the clinically acceptable range of 5.9–7.8 MPa, as suggested by Reynolds (1975). The nanoionomer groups gave significantly lower ARI values than the conventional adhesive group. Conclusion: Based on this in-vitro study, nanoionomer with etching can be successfully used as an orthodontic bonding agent leaving less adhesive remnant on enamel surface, making cleaning easier. However, in-vivo studies are needed to confirm the validity

  2. HFPK 334: An unusual supernova remnant in the Small Magellanic Cloud

    SciTech Connect

    Crawford, E. J.; Filipović, M. D.; McEntaffer, R. L.; Brantseg, T.; Heitritter, K.; Roper, Q.; Haberl, F.; Urošević, D.

    2014-11-01

    We present new Australia Telescope Compact Array radio-continuum and XMM-Newton/Chandra X-ray Observatory observations of the unusual supernova remnant (SNR) HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell-type morphology in the radio continuum and has a size of ∼20 pc at the SMC distance. The X-ray morphology is similar; however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best-fit power law with a photon index of Γ = 2.7 ± 0.5. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and points toward a younger SNR with an age of ≲ 1800 yr. With an average radio spectral index of α = –0.59 ± 0.09, we find that an equipartition magnetic field for the remnant is ∼90 μG, a value typical of younger SNRs in low-density environments. Also, we report the detection of scattered radio polarization across the remnant at 20 cm, with a peak fractional polarization level of 25% ± 5%.

  3. HFPK 334: An Unusual Supernova Remnant in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Crawford, E. J.; Filipović, M. D.; McEntaffer, R. L.; Brantseg, T.; Heitritter, K.; Roper, Q.; Haberl, F.; Urošević, D.

    2014-11-01

    We present new Australia Telescope Compact Array radio-continuum and XMM-Newton/Chandra X-ray Observatory observations of the unusual supernova remnant (SNR) HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell-type morphology in the radio continuum and has a size of ~20 pc at the SMC distance. The X-ray morphology is similar; however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best-fit power law with a photon index of Γ = 2.7 ± 0.5. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and points toward a younger SNR with an age of <~ 1800 yr. With an average radio spectral index of α = -0.59 ± 0.09, we find that an equipartition magnetic field for the remnant is ~90 μG, a value typical of younger SNRs in low-density environments. Also, we report the detection of scattered radio polarization across the remnant at 20 cm, with a peak fractional polarization level of 25% ± 5%.

  4. Runaway Stars in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Pannicke, Anna; Neuhaeuser, Ralph; Dinçel, Baha

    2016-07-01

    Half of all stars and in particular 70 % of the massive stars are a part of a multiple system. A possible development for the system after the core collapse supernova (SN) of the more massive component is as follows: The binary is disrupted by the SN. The formed neutron star is ejected by the SN kick whereas the companion star either remains within the system and is gravitationally bounded to the neutron star, or is ejected with a spatial velocity comparable to its former orbital velocity (up to 500 km/s). Such stars with a large peculiar space velocity are called runaway stars. We present our observational results of the supernova remnants (SNRs) G184.6-5.8, G74.0-8.5 and G119.5+10.2. The focus of this project lies on the detection of low mass runaway stars. We analyze the spectra of a number of candidates and discuss their possibility of being the former companions of the SN progenitor stars. The spectra were obtained with INT in Tenerife, Calar Alto Astronomical Observatory and the University Observatory Jena. Also we investigate the field stars in the neighborhood of the SNRs G74.0-8.5 and G119.5+10.2 and calculate more precise distances for these SNRs.

  5. Congenital esophageal stenosis owing to tracheobronchial remnants

    PubMed Central

    Rebelo, Priscila Guyt; Ormonde, João Victor C.; Ormonde, João Baptista C.

    2013-01-01

    OBJECTIVE To emphasize the need of an accurate diagnosis of congenital esophageal stenosis due to tracheobronchial remnants, since its treatment differs from other types of congenital narrowing. CASE DESCRIPTION Four cases of lower congenital esophageal stenosis due to tracheobronchial remnants, whose definitive diagnosis was made by histopathology. Except for the last case, in which a concomitant anti-reflux surgery was not performed, all had a favorable outcome after resection and anastomosis of the esophagus. COMMENTS The congenital esophageal stenosis is an intrinsic narrowing of the organâ€(tm)s wall associated with its structural malformation. The condition can be caused by tracheobronchial remnants, fibromuscular stenosis or membranous diaphragm and the first symptom is dysphagia after the introduction of solid food in the diet. The first-choice treatment to tracheobronchial remnants cases is the surgical resection and end-to-end anastomosis of the esophagus. PMID:24142326

  6. Isaac's Remnants; Tropical Storms Kirk, Michael

    NASA Video Gallery

    Animation of GOES-13 satellite observations from Sept. 1-4, 2012, showing Isaac's remnants move from the central to eastern U.S., Tropical Storm Leslie nearing Bermuda, Kirk fading in the No. Atlan...

  7. Fermi Proves Supernova Remnants Make Cosmic Rays

    NASA Video Gallery

    The husks of exploded stars produce some of the fastest particles in the cosmos. New findings by NASA's Fermi show that two supernova remnants accelerate protons to near the speed of light. The pro...

  8. Supernova remnants: the X-ray perspective

    NASA Astrophysics Data System (ADS)

    Vink, Jacco

    2012-12-01

    Supernova remnants are beautiful astronomical objects that are also of high scientific interest, because they provide insights into supernova explosion mechanisms, and because they are the likely sources of Galactic cosmic rays. X-ray observations are an important means to study these objects. And in particular the advances made in X-ray imaging spectroscopy over the last two decades has greatly increased our knowledge about supernova remnants. It has made it possible to map the products of fresh nucleosynthesis, and resulted in the identification of regions near shock fronts that emit X-ray synchrotron radiation. Since X-ray synchrotron radiation requires 10-100 TeV electrons, which lose their energies rapidly, the study of X-ray synchrotron radiation has revealed those regions where active and rapid particle acceleration is taking place. In this text all the relevant aspects of X-ray emission from supernova remnants are reviewed and put into the context of supernova explosion properties and the physics and evolution of supernova remnants. The first half of this review has a more tutorial style and discusses the basics of supernova remnant physics and X-ray spectroscopy of the hot plasmas they contain. This includes hydrodynamics, shock heating, thermal conduction, radiation processes, non-equilibrium ionization, He-like ion triplet lines, and cosmic ray acceleration. The second half offers a review of the advances made in field of X-ray spectroscopy of supernova remnants during the last 15 year. This period coincides with the availability of X-ray imaging spectrometers. In addition, I discuss the results of high resolution X-ray spectroscopy with the Chandra and XMM-Newton gratings. Although these instruments are not ideal for studying extended sources, they nevertheless provided interesting results for a limited number of remnants. These results provide a glimpse of what may be achieved with future microcalorimeters that will be available on board future X

  9. X-ray spectra of supernova remnants

    NASA Technical Reports Server (NTRS)

    Szymkowiak, A. E.

    1985-01-01

    X-ray spectra were obtained from fields in three supernova remnants with the solid state spectrometer of the HEAO 2 satellite. These spectra, which contain lines from K-shell transitions of several abundant elements with atomic numbers between 10 and 22, were compared with various models, including some of spectra that would be produced by adiabatic phase remnants when the time-dependence of the ionization is considered.

  10. The Rediscovery of the Antlia Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Orchard, Alexander; Benjamin, Robert A.; Gostisha, Martin; Haffner, L. Matthew; Hill, Alex S.; Barger, Kathleen

    2015-01-01

    While undertaking a survey of velocity-resolved diffuse optical emission from the [S II] 6716 A line with the Wisconsin H-alpha Mapper, we have rediscovered the Antlia Supernova remnant, a 26 degree diameter remmant near the Gum Nebula that was originally detected in SHASSA (Southern H-alpha Sky Survey Atlas) by P. McCullough in 2002. The original discovery showed this remnant was associated with ¼ keV X-ray emission in the ROSAT All-Sky Survey, and argued that Antlia was potentially the closest remnant to the Sun. We will present an analysis of the H-alpha and [S II] lines in this direction: the ratio of these lines indicate the shell is consistent with being a supernova remnant and the velocities allow us to constrain its age. We discuss this remnant in the context of the evolution of the entire Gum Nebula region, noting that its proximity and age make it possible to search for geochemical evidence of this remnant on Earth. This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.

  11. Multi-frequency study of supernova remnants in the Large Magellanic Cloud. Confirmation of the supernova remnant status of DEM L205

    NASA Astrophysics Data System (ADS)

    Maggi, P.; Haberl, F.; Bozzetto, L. M.; Filipović, M. D.; Points, S. D.; Chu, Y.-H.; Sasaki, M.; Pietsch, W.; Gruendl, R. A.; Dickel, J.; Smith, R. C.; Sturm, R.; Crawford, E. J.; De Horta, A. Y.

    2012-10-01

    Context. The Large Magellanic Cloud (LMC) is an ideal target for the study of an unbiased and complete sample of supernova remnants (SNRs). We started an X-ray survey of the LMC with XMM-Newton, which, in combination with observations at other wavelengths, will allow us to discover and study remnants that are either even fainter or more evolved (or both) than previously known. Aims: We present new X-ray and radio data of the LMC SNR candidate DEM L205, obtained by XMM-Newton and ATCA, along with archival optical and infrared observations. Methods: We use data at various wavelengths to study this object and its complex neighbourhood, in particular in the context of the star formation activity, past and present, around the source. We analyse the X-ray spectrum to derive some remnant's properties, such as age and explosion energy. Results: Supernova remnant features are detected at all observed wavelengths : soft and extended X-ray emission is observed, arising from a thermal plasma with a temperature kT between 0.2 keV and 0.3 keV. Optical line emission is characterised by an enhanced [S ii]-to-Hα ratio and a shell-like morphology, correlating with the X-ray emission. The source is not or only tentatively detected at near-infrared wavelengths (shorter than 10 μm), but there is a detection of arc-like emission at mid and far-infrared wavelengths (24 and 70 μm) that can be unambiguously associated with the remnant. We suggest that thermal emission from dust heated by stellar radiation and shock waves is the main contributor to the infrared emission. Finally, an extended and faint non-thermal radio emission correlates with the remnant at other wavelengths and we find a radio spectral index between -0.7 and -0.9, within the range for SNRs. The size of the remnant is ~79 × 64 pc and we estimate a dynamical age of about 35 000 years. Conclusions: We definitely confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants known in the LMC. The numerous

  12. Supernova Remnant in 3-D

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Click on the image for the movie

    For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, infrared data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly iron observed in X-rays. The yellow region is a combination of argon and silicon seen in X-rays, optical, and infrared including jets of silicon plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.

    Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.

    To create this visualization, scientists took advantage of both a previously known phenomenon the Doppler effect and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as iron, silicon and argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer

  13. Supernova Remnant in 3-D

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Click on the image for the movie

    For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, infrared data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly iron observed in X-rays. The yellow region is a combination of argon and silicon seen in X-rays, optical, and infrared including jets of silicon plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.

    Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.

    To create this visualization, scientists took advantage of both a previously known phenomenon the Doppler effect and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as iron, silicon and argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer

  14. Supernova 1987A: a Template to Link Supernovae to Their Remnants

    NASA Astrophysics Data System (ADS)

    Orlando, S.; Miceli, M.; Pumo, M. L.; Bocchino, F.

    2015-09-01

    The emission of supernova remnants (SNRs) reflects the properties of both the progenitor supernovae (SNe) and the surrounding environment. The complex morphology of the remnants, however, hampers the disentanglement of the two contributions. Here, we aim at identifying the imprint of SN 1987A on the X-ray emission of its remnant and at constraining the structure of the environment surrounding the SN. We performed high-resolution hydrodynamic simulations describing SN 1987A soon after the core-collapse and the following three-dimensional expansion of its remnant between days 1 and 15,000 after the SN. We demonstrated that the physical model reproducing the main observables of SN 1987A during the first 250 days of evolution also reproduces the X-ray emission of the subsequent expanding remnant, thus bridging the gap between SNe and SNRs. By comparing model results with observations, we constrained the explosion energy in the range 1.2–1.4 × 1051 erg and the envelope mass in the range 15–17 M ⊙. We found that the shape of X-ray lightcurves and spectra at early epochs (<15 years) reflects the structure of outer ejecta: our model reproduces the observations if the outermost ejecta have a post-explosion radial profile of density approximated by a power law with index α = ‑8. At later epochs, the shapes of X-ray lightcurves and spectra reflect the density structure of the nebula around SN 1987A. This enabled us to ascertain the origin of the multi-thermal X-ray emission, disentangle the imprint of the SN on the remnant emission from the effects of the remnant interaction with the environment, and constrain the pre-supernova structure of the nebula.

  15. Branchial remnants: a review of 58 cases.

    PubMed

    Doi, O; Hutson, J M; Myers, N A; McKelvie, P A

    1988-09-01

    Most congenital lateral cervical cysts, fistulae, and skin tags are considered to be from the branchial apparatus. This is a 13-year review of 58 patients (with 66 branchial lesions) who were operated on. There were eight simple cysts and six cysts with a fistula; 43 external fistulae with or without an internal opening, and nine skin tags. Eighty-seven percent (39/45) of patients with skin tags and external fistulae were less than 5 years of age at the time of operation. On the other hand, all eight patients with cysts but no fistula were greater than 9 years of age. Eight lesions were considered to be the first branchial remnants, and 44 lesions were suspected to be from the second branchial cleft. One external fistula with an internal communication to the pharynx at the level of thyrohyoid membrane was considered to be a third (or fourth) branchial remnant. The other branchial cyst with thyroid tissue in its wall was suggested to be a fourth branchial remnant. Pathology of the excised lesions showed columnar, squamous, or a mixed epithelium. Lymphoid aggregates were documented in 31 patients. Duration of hospital stay was short, except for four patients with first cleft defects who stayed more than five days. Three of the four recurrent cases were first branchial remnants, including one case with the first operation performed at another hospital. In view of these findings, first branchial remnants must be excised with extra care. PMID:3183888

  16. The radio remnant of Supernova 1987A at high frequencies and high resolution

    NASA Astrophysics Data System (ADS)

    Zanardo, G.; Staveley-Smith, L.; Ng, C.-Y.; Gaensler, B. M.; Potter, T. M.; Manchester, R. N.; Tzioumis, A. K.

    2014-01-01

    As the remnant of Supernova (SN) 1987A has been getting brighter over time, new observations at high frequencies have allowed imaging of the radio emission at unprecedented detail. We present a new radio image at 44 GHz of the supernova remnant (SNR), derived from observations performed with the Australia Telescope Compact Array (ATCA) in 2011. The diffraction-limited image has a resolution of 349×225 mas, which is the highest achieved to date in high-dynamic range images of the SNR. We also present a new image at 18 GHz, also derived from ATCA observations performed in 2011, which is super-resolved to 0''.25. The new 44 and 18 GHz images yield the first high-resolution spectral index map of the remnant. The comparison of the 44 GHz image with contemporaneous X-ray and Hα observations allows further investigations of the nature of the remnant asymmetry and sheds more light into the progenitor hypotheses and SN explosion. In light of simple free-free absorption models, we discuss the likelihood of detecting at 44 GHz the possible emission originating from a pulsar wind nebula (PWN) or a compact source in the centre of the remnant.

  17. Does the time interval after bleaching influence the adhesion of orthodontic brackets?

    PubMed Central

    Nascimento, Glaucia Cristina Rodrigues; de Miranda, Cyndi Albuquerque; Machado, Sissy Maria Mendes; Brandão, Gustavo Antonio Martins; de Almeida, Haroldo Amorim

    2013-01-01

    Objective To test the null hypothesis that no difference exists between the effects of at-home bleaching and in-office bleaching on shear bond strength (SBS) with bracket bonding at 4 different time intervals after dental bleaching. Methods Ninety extracted human premolars were randomly divided into 9 groups (n = 10) according to the bleaching methods used (at-home bleaching and in-office bleaching) and the storage time in artificial saliva (30 min, 1 day, 2 weeks, and 3 weeks before bonding). The control group was stored in artificial saliva for 7 days. Brackets were bonded with the Transbond XT adhesive system, and SBS testing was performed. The adhesive remnant index (ARI) was used to assess the amount of resin remaining on the enamel surfaces after debonding. The SBS data were analyzed by analysis of variance (ANOVA) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. Significance for all statistical tests was predetermined to be p < 0.05. Results The SBS of the unbleached group was significantly higher (p < 0.05) than that of the bleached groups (except for the group bonded 30 min after at-home bleaching). Conclusions The null hypothesis was not totally rejected. All bleaching groups tested had decreased SBS of the brackets to the enamel, except for the group bonded 30 min after at-home bleaching. The SBS returned to values close to those of the unbleached enamel within 3 weeks following bleaching. PMID:24228239

  18. Antlia Supernova Remnant in Far-ultraviolet

    NASA Astrophysics Data System (ADS)

    Shinn, Jong-Ho; Min, K. W.; Seon, K.; Lim, Y.; Edelstein, J.; Han, W.; Sankrit, R.; FIMS Team at KAIST; FIMS Team at KASI; SPEAR Team at SSL

    2006-09-01

    Antlia supernova remnant (l = 276.52°, b = +19.05°) was recently discovered by McCullough et al. (2002), and its angular size ( 24°) is comparable to Monogem Ring. It shows a diffuse appearance in soft X-ray, which is anti-correlated with 100 μm infrared emission and surrounded by annular enhancements in Hα. We present the far-ultraviolet view of the remnant observed with Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR), also known as Far-ultraviolet IMaging Spectrograph (FIMS). C IV λ and Si II emission lines were detected in the remnant region, and their emission-line maps show a rough anti-correlation with a soft X-ray map (ROSAT All Sky Survey 0.25 keV map).

  19. Isothermal blast wave model of supernova remnants

    NASA Technical Reports Server (NTRS)

    Solinger, A.; Buff, J.; Rappaport, S.

    1975-01-01

    The validity of the 'adiabatic' assumption in supernova-remnant calculations is examined, and the alternative extreme of an isothermal blast wave is explored. It is concluded that, because of thermal conductivity, the large temperature gradients predicted by the adiabatic model probably are not maintained in nature. Self-similar solutions to the hydrodynamic equations for an isothermal blast wave have been found and studied. These solutions are then used to determine the relationship between X-ray observations and inferred parameters of supernova remnants. A comparison of the present results with those for the adiabatic model indicates differences which are less than present observational uncertainties. It is concluded that most parameters of supernova remnants inferred from X-ray measurements are relatively insensitive to the specifics of the blast-wave model.

  20. REMNANTS OF BINARY WHITE DWARF MERGERS

    SciTech Connect

    Raskin, Cody; Scannapieco, Evan; Timmes, F. X.; Fryer, Chris; Rockefeller, Gabriel

    2012-02-10

    We carry out a comprehensive smooth particle hydrodynamics simulation survey of double-degenerate white dwarf binary mergers of varying mass combinations in order to establish correspondence between initial conditions and remnant configurations. We find that all but one of our simulation remnants share general properties such as a cold, degenerate core surrounded by a hot disk, while our least massive pair of stars forms only a hot disk. We characterize our remnant configurations by the core mass, the rotational velocity of the core, and the half-mass radius of the disk. We also find that some of our simulations with very massive constituent stars exhibit helium detonations on the surface of the primary star before complete disruption of the secondary. However, these helium detonations are insufficiently energetic to ignite carbon, and so do not lead to prompt carbon detonations.

  1. Pulsar reenergization of old supernova remnant shells

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Fesen, Robert A.; Saken, Jon M.

    1989-01-01

    The morphology of several unusual composite remnants are suggested to be affected by previously unrecognized interactions between high-velocity pulsars and old SNR shells, and the case of CTB 80 is pointed out as a likely example of such interactions. The interactions generate a new class of 'composite remnants' and furnish a novel method for the derivation of kinematic distances and SNR ages; this technique is noted to be especially useful when the pulsar has a measured spindown age or proper motion. It is predicted that a number of pulsars may interact with 80-100 pc radius 'superbubbles' produced by the combined action of winds and supernovae in OB associations.

  2. Planck intermediate results. XXXI. Microwave survey of Galactic supernova remnants

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Brogan, C. L.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Colombi, S.; Colombo, L. P. L.; Crill, B. P.; Curto, A.; Cuttaia, F.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Doré, O.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hobson, M.; Holmes, W. A.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Maino, D.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Noviello, F.; Novikov, D.; Novikov, I.; Oppermann, N.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paladini, R.; Pasian, F.; Peel, M.; Perdereau, O.; Perrotta, F.; Piacentini, F.; Piat, M.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Reich, W.; Reinecke, M.; Remazeilles, M.; Renault, C.; Rho, J.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Stolyarov, V.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-02-01

    The all-sky Planck survey in 9 frequency bands was used to search for emission from all 274 known Galactic supernova remnants. Of these, 16 were detected in at least two Planck frequencies. The radio-through-microwave spectral energy distributions were compiled to determine the mechanism for microwave emission. In only one case, IC 443, is there high-frequency emission clearly from dust associated with the supernova remnant. In all cases, the low-frequency emission is from synchrotron radiation. As predicted for a population of relativistic particles with energy distribution that extends continuously to high energies, a single power law is evident for many sources, including the Crab and PKS 1209-51/52. A decrease in flux density relative to the extrapolation of radio emission is evident in several sources. Their spectral energy distributions can be approximated as broken power laws, Sν ∝ ν-α, with the spectral index, α, increasing by 0.5-1 above a break frequency in the range 10-60 GHz. The break could be due to synchrotron losses.

  3. HIGH RESOLUTION 36 GHz IMAGING OF THE SUPERNOVA REMNANT OF SN 1987A

    SciTech Connect

    Potter, T. M.; Staveley-Smith, L.; Zanardo, G.; Ng, C.-Y.; Gaensler, B. M.; Ball, Lewis; Kesteven, M. J.; Manchester, R. N.; Tzioumis, A. K.

    2009-11-01

    The aftermath of supernova (SN) 1987A continues to provide spectacular insights into the interaction between an SN blastwave and its circumstellar environment. We here present 36 GHz observations from the Australia Telescope Compact Array of the radio remnant of SN 1987A. These new images, taken in 2008 April and 2008 October, substantially extend the frequency range of an ongoing monitoring and imaging program conducted between 1.4 and 20 GHz. Our 36.2 GHz images have a diffraction-limited angular resolution of 0.''3-0.''4, which covers the gap between high resolution, low dynamic range VLBI images of the remnant and low resolution, high dynamic range images at frequencies between 1 and 20 GHz. The radio morphology of the remnant at 36 GHz is an elliptical ring with enhanced emission on the eastern and western sides, similar to that seen previously at lower frequencies. Model fits to the data in the Fourier domain show that the emitting region is consistent with a thick inclined torus of mean radius 0.''85, and a 2008 October flux density of 27 +- 6 mJy at 36.2 GHz. The spectral index for the remnant at this epoch, determined between 1.4 GHz and 36.2 GHz, is alpha = -0.83. There is tentative evidence for an unresolved central source with flatter spectral index.

  4. HIGH-RESOLUTION RADIO OBSERVATIONS OF THE REMNANT OF SN 1987A AT HIGH FREQUENCIES

    SciTech Connect

    Zanardo, Giovanna; Staveley-Smith, L.; Potter, T. M.; Ng, C.-Y.; Gaensler, B. M.; Manchester, R. N.; Tzioumis, A. K.

    2013-04-20

    We present new imaging observations of the remnant of Supernova (SN) 1987A at 44 GHz, performed in 2011 with the Australia Telescope Compact Array (ATCA). The 0.''35 Multiplication-Sign 0.''23 resolution of the diffraction-limited image is the highest achieved to date in high-dynamic range. We also present a new ATCA image at 18 GHz derived from 2011 observations, which is super-resolved to 0.''25. The flux density is 40 {+-} 2 mJy at 44 GHz and 81 {+-} 6 mJy at 18 GHz. At both frequencies, the remnant exhibits a ring-like emission with two prominent lobes, and an east-west brightness asymmetry that peaks on the eastern lobe. A central feature of fainter emission appears at 44 GHz. A comparison with previous ATCA observations at 18 and 36 GHz highlights higher expansion velocities of the remnant's eastern side. The 18-44 GHz spectral index is {alpha} = -0.80 (S{sub {nu}}{proportional_to}{nu}{sup {alpha}}). The spectral index map suggests slightly steeper values at the brightest sites on the eastern lobe, whereas flatter values are associated with the inner regions. The remnant morphology at 44 GHz generally matches the structure seen with contemporaneous X-ray and H{alpha} observations. Unlike the H{alpha} emission, both the radio and X-ray emission peaks on the eastern lobe. The regions of flatter spectral index align and partially overlap with the optically visible ejecta. Simple free-free absorption models suggest that emission from a pulsar wind nebula or a compact source inside the remnant may now be detectable at high frequencies or at low frequencies if there are holes in the ionized component of the ejecta.

  5. Perforated Carcinoma in the Gastric Remnant: A Case of Conservative Treatment Prior to Successful Curative R0 Resection

    PubMed Central

    Kawashima, Hiroshi; Toyoda, Sho; Okumura, Satoshi; Yamamoto, Kansuke; Mizumura, Naoto; Ito, Aya; Maehira, Hiromitsu; Imagawa, Atsuo; Ogawa, Masao; Kawasaki, Masayasu; Kameyama, Masao

    2016-01-01

    An 80-year-old man who had undergone distal gastrectomy and Billroth-II gastrojejunostomy 38 years previously, for a benign gastric ulcer, was diagnosed with remnant gastric cancer based on upper gastrointestinal endoscopy findings. He presented at our emergency department with acute-onset epigastric pain due to perforated remnant gastric cancer. Conservative medical management was selected, including nasogastric tube insertion, antibiotics, and proton pump inhibitors, because his peritonitis was limited to his epigastrium and his general condition was stable. Twenty-one days after the perforation occurred, curative total remnant gastrectomy and D2 lymphadenectomy were performed. Adhesion between the lateral segment of the liver and the dissected lesser curvature of the gastric remnant may have contributed to the peritonitis in this case, which was limited to the epigastrium. This is the first report of perforated remnant gastric cancer in which conservative treatment was effective prior to curative resection. The protocol reported here may be of use to other clinicians who may encounter this clinical entity in their practices.

  6. Perforated Carcinoma in the Gastric Remnant: A Case of Conservative Treatment Prior to Successful Curative R0 Resection.

    PubMed

    Yuu, Ken; Kawashima, Hiroshi; Toyoda, Sho; Okumura, Satoshi; Yamamoto, Kansuke; Mizumura, Naoto; Ito, Aya; Maehira, Hiromitsu; Imagawa, Atsuo; Ogawa, Masao; Kawasaki, Masayasu; Kameyama, Masao

    2016-01-01

    An 80-year-old man who had undergone distal gastrectomy and Billroth-II gastrojejunostomy 38 years previously, for a benign gastric ulcer, was diagnosed with remnant gastric cancer based on upper gastrointestinal endoscopy findings. He presented at our emergency department with acute-onset epigastric pain due to perforated remnant gastric cancer. Conservative medical management was selected, including nasogastric tube insertion, antibiotics, and proton pump inhibitors, because his peritonitis was limited to his epigastrium and his general condition was stable. Twenty-one days after the perforation occurred, curative total remnant gastrectomy and D2 lymphadenectomy were performed. Adhesion between the lateral segment of the liver and the dissected lesser curvature of the gastric remnant may have contributed to the peritonitis in this case, which was limited to the epigastrium. This is the first report of perforated remnant gastric cancer in which conservative treatment was effective prior to curative resection. The protocol reported here may be of use to other clinicians who may encounter this clinical entity in their practices. PMID:27651972

  7. Perforated Carcinoma in the Gastric Remnant: A Case of Conservative Treatment Prior to Successful Curative R0 Resection

    PubMed Central

    Kawashima, Hiroshi; Toyoda, Sho; Okumura, Satoshi; Yamamoto, Kansuke; Mizumura, Naoto; Ito, Aya; Maehira, Hiromitsu; Imagawa, Atsuo; Ogawa, Masao; Kawasaki, Masayasu; Kameyama, Masao

    2016-01-01

    An 80-year-old man who had undergone distal gastrectomy and Billroth-II gastrojejunostomy 38 years previously, for a benign gastric ulcer, was diagnosed with remnant gastric cancer based on upper gastrointestinal endoscopy findings. He presented at our emergency department with acute-onset epigastric pain due to perforated remnant gastric cancer. Conservative medical management was selected, including nasogastric tube insertion, antibiotics, and proton pump inhibitors, because his peritonitis was limited to his epigastrium and his general condition was stable. Twenty-one days after the perforation occurred, curative total remnant gastrectomy and D2 lymphadenectomy were performed. Adhesion between the lateral segment of the liver and the dissected lesser curvature of the gastric remnant may have contributed to the peritonitis in this case, which was limited to the epigastrium. This is the first report of perforated remnant gastric cancer in which conservative treatment was effective prior to curative resection. The protocol reported here may be of use to other clinicians who may encounter this clinical entity in their practices. PMID:27651972

  8. The Cygnus Loop: An Older Supernova Remnant.

    ERIC Educational Resources Information Center

    Straka, William

    1987-01-01

    Describes the Cygnus Loop, one of brightest and most easily studied of the older "remnant nebulae" of supernova outbursts. Discusses some of the historical events surrounding the discovery and measurement of the Cygnus Loop and makes some projections on its future. (TW)

  9. L-D dependence for supernova remnants

    NASA Astrophysics Data System (ADS)

    Stanković, M.; Tešić, Lj.; Urošević, D.

    2003-10-01

    We discuss here the L-D relation (the possible dependence of the radio luminosity on linear diameter) for the supernova remnants (SNRs) in order to see wether determination of SNR distances on the basis of Σ-D relation is possible.

  10. Gamma-Ray Emission From Crushed Clouds in Supernova Remnants

    SciTech Connect

    Uchiyama, Yasunobu; Blandford, Roger D.; Funk, Stefan; Tajima, Hiroyasu; Tanaka, Takaaki; /KIPAC, Menlo Park

    2010-10-27

    It is shown that the radio and gamma-ray emission observed from newly-found 'GeV-bright' supernova remnants (SNRs) can be explained by a model, in which a shocked cloud and shock-accelerated cosmic rays (CRs) frozen in it are simultaneously compressed by the supernova blastwave as a result of formation of a radiative cloud shock. Simple reacceleration of pre-existing CRs is generally sufficient to power the observed gamma-ray emission through the decays of {pi}{sup 0}-mesons produced in hadronic interactions between high-energy protons (nuclei) and gas in the compressed-cloud layer. This model provides a natural account of the observed synchrotron radiation in SNRs W51C, W44 and IC 443 with flat radio spectral index, which can be ascribed to a combination of secondary and reaccelerated electrons and positrons.

  11. Approximate supernova remnant dynamics with cosmic ray production

    NASA Technical Reports Server (NTRS)

    Voelk, H. J.; Drury, L. O.; Dorfi, E. A.

    1985-01-01

    Supernova explosions are the most violent and energetic events in the galaxy and have long been considered probably sources of Cosmic Rays. Recent shock acceleration models treating the Cosmic Rays (CR's) as test particles nb a prescribed Supernova Remnant (SNR) evolution, indeed indicate an approximate power law momentum distribution f sub source (p) approximation p(-a) for the particles ultimately injected into the Interstellar Medium (ISM). This spectrum extends almost to the momentum p = 1 million GeV/c, where the break in the observed spectrum occurs. The calculated power law index approximately less than 4.2 agrees with that inferred for the galactic CR sources. The absolute CR intensity can however not be well determined in such a test particle approximation.

  12. A Multiwavelength Study of Tycho's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Petre, Robert

    The remnant of the supernova of 1572 A.D., now known as Tycho's Supernova Remnant (SNR), is one of the most well studied SNRs in existence, having been observed with telescopes from radio waves to gamma-rays. We propose a multi-wavelength study of this remnant, with particular focus on archival data in the infrared from Spitzer, WISE, and Herschel, and in gamma-rays from Fermi. The IR data is of extremely high-quality, and will allow us to answer or further constrain several mysteries regarding Tycho, known to be the remnant of a Type Ia supernova. Is the remnant a source of particle acceleration producing cosmic-rays in excess of 10^15 ev? What is the source of the gamma-ray emission seen at both GeV and TeV energies? What is the nature of the medium surrounding the remnant, into which it is currently expanding at over 4000 km/s? Has any dust formed in the iron-rich ejected material from the supernova? The answers to all of these questions will require a multi-wavelength approach, and we will supplement the IR and gamma-ray data here with archival X-ray data from both Chandra and XMM- Newton. In young SNRs like Tycho, IR and X-ray emission is inherently connected, since the hot ions and electrons that give rise to the thermal X-ray emission also heat (and destroy) dust grains in the post-shock gas. Infrared spectroscopy is a highly sensitive function of gas density, and provides a more powerful diagnostic tool for this parameter than X-rays alone do. This post-shock density is a crucial parameter for both particle acceleration and gamma-ray emission models, and the IR data will allow us to measure this density at any point in the remnant. We will explore the relationship between dust and gas in the immediate post-shock region. Because the blast wave is encountering the ambient Galactic ISM, this will provide strong constraints on the dust composition and dust-to-gas mass ratio in the general ISM. At all wavelengths, Tycho is a wealth of information, and by

  13. Molecular environment of the supernova remnant IC 443: Discovery of the molecular shells surrounding the remnant

    SciTech Connect

    Su, Yang; Fang, Min; Yang, Ji; Zhou, Ping; Chen, Yang

    2014-06-20

    We have carried out {sup 12}CO, {sup 13}CO, and C{sup 18}O observations toward the mixed morphology supernova remnant (SNR) IC 443. The observations cover a 1.°5 × 1.°5 area and allow us to investigate the overall molecular environment of the remnant. Some northern and northeastern partial shell structure of CO gas is around the remnant. One of the partial shells, about 5' extending beyond the northeastern border of the remnant's bright radio shell, seems to just confine the faint radio halo. On the other hand, some faint CO clumps can be discerned along the eastern boundary of the faint remnant's radio halo. Connecting the eastern CO clumps, the northeastern partial shell structures, and the northern CO partial shell, we can see that a half molecular ring structure appears to surround the remnant. The LSR velocity of the half-ring structure is in the range of –5 km s{sup –1} to –2 km s{sup –1}, which is consistent with that of the –4 km s{sup –1} molecular clouds. We suggest that the half-ring structure of the CO emission at V {sub LSR} ∼ –4 km s{sup –1} is associated with the SNR. The structures are possibly swept up by the stellar winds of SNR IC 443's massive progenitor. Based on the Wide-field Infrared Survey Explorer and the Two Micron All Sky Survey near-IR database, 62 young stellar object (YSO) candidates are selected within the radio halo of the remnant. These YSO candidates concentrated along the boundary of the remnant's bright radio shell are likely to be triggered by the stellar winds from the massive progenitor of SNR IC 443.

  14. Thermal Characterization of Adhesive

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.

    1999-01-01

    The current Space Shuttle Reusable Solid Rocket Motor (RSRM) nozzle adhesive bond system is being replaced due to obsolescence. Down-selection and performance testing of the structural adhesives resulted in the selection of two candidate replacement adhesives, Resin Technology Group's Tiga 321 and 3M's EC2615XLW. This paper describes rocket motor testing of these two adhesives. Four forty-pound charge motors were fabricated in configurations that would allow side by side comparison testing of the candidate replacement adhesives and the current RSRM adhesives. The motors provided an environment where the thermal performance of adhesives in flame surface bondlines was compared. Results of the FPC testing show that: 1) The phenolic char depths on radial bond lines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used; 2) The adhesive char depth of the candidate replacement adhesives is less than the char depth of the current adhesives; 3) The heat-affected depth of the candidate replacement adhesives is less than the heat-affected depth of the current adhesives; and 4) The ablation rates for both replacement adhesives are slower than that of the current adhesives.

  15. Supernova Remnants in the Magellanic Clouds. VI. The DEM L316 Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Williams, R. M.; Chu, Y.-H.

    2005-12-01

    The DEM L316 system contains two shells, both with the characteristic signatures of supernova remnants (SNRs). We analyze Chandra and XMM-Newton data for DEM L316, investigating its spatial and spectral X-ray features. Our Chandra observations resolve the structure of the northeastern SNR (shell A) as a bright inner ring and a set of ``arcs'' surrounded by fainter diffuse emission. The spectrum is well fit by a thermal plasma model with a temperature of ~1.4 keV; we do not find significant spectral differences for different regions of this SNR. The southwestern SNR (shell B) exhibits an irregular X-ray outline, with a brighter interior ring of emission including a bright knot of emission. Overall, the emission of the SNR is well described by a thermal plasma of temperature ~0.6 keV. The bright knot, however, is spectrally distinct from the rest of the SNR, requiring the addition of a high-energy spectral component consistent with a power-law spectrum of photon index 1.6-1.8. We confirm the findings of Nishiuchi and coworkers that the spectra of these shells are notably different, with shell A requiring a high iron abundance for a good spectral fit, implying a Type Ia origin. We further explicitly compare abundance ratios to model predictions for Type Ia and Type II supernovae. The low ratios for shell A (O/Fe of 1.5 and Ne/Fe of 0.2) and the high ratios for shell B (O/Fe of 30-130 and Ne/Fe of 8-16) are consistent with Type Ia and Type II origins, respectively. The difference between the SNR progenitor types casts some doubt on the suggestion that these SNRs are interacting with one another.

  16. Imagery and spectroscopy of supernova remnants and H-2 regions

    NASA Technical Reports Server (NTRS)

    Dufour, R. J.

    1984-01-01

    Research activities relating to supernova remnants were summarized. The topics reviewed include: progenitor stars of supernova remnants, UV/optical/radio/X-ray imagery of selected regions in the Cygnus Loop, UV/optical spectroscopy of the Cygnus Loop spur, and extragalactic supernova remnant spectra.

  17. Understanding Marine Mussel Adhesion

    PubMed Central

    Roberto, Francisco F.

    2007-01-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are water-impervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion. PMID:17990038

  18. Understanding Marine Mussel Adhesion

    SciTech Connect

    H. G. Silverman; F. F. Roberto

    2007-12-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are waterimpervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion.

  19. Two evolved supernova remnants with newly identified Fe-rich cores in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kavanagh, P. J.; Sasaki, M.; Bozzetto, L. M.; Points, S. D.; Crawford, E. J.; Dickel, J.; Filipović, M. D.; Haberl, F.; Maggi, P.; Whelan, E. T.

    2016-02-01

    Aims: We present a multi-wavelength analysis of the evolved supernova remnants MCSNR J0506-7025 and MCSNR J0527-7104 in the Large Magellanic Cloud. Methods: We used observational data from XMM-Newton, the Australian Telescope Compact Array, and the Magellanic Cloud Emission Line Survey to study their broad-band emission and used Spitzer and H i data to gain a picture of the environment into which the remnants are expanding. We performed a multi-wavelength morphological study and detailed radio and X-ray spectral analyses to determine their physical characteristics. Results: Both remnants were found to have bright X-ray cores, dominated by Fe L-shell emission, which is consistent with reverse shock-heated ejecta with determined Fe masses in agreement with Type Ia explosion yields. A soft X-ray shell, which is consistent with swept-up interstellar medium, was observed in MCSNR J0506-7025, suggestive of a remnant in the Sedov phase. Using the spectral fit results and the Sedov self-similar solution, we estimated the age of MCSNR J0506-7025 to be ~16-28 kyr, with an initial explosion energy of (0.07-0.84) × 1051 erg. A soft shell was absent in MCSNR J0527-7104, with only ejecta emission visible in an extremely elongated morphology that extends beyond the optical shell. We suggest that the blast wave has broken out into a low density cavity, allowing the shock heated ejecta to escape. We find that the radio spectral index of MCSNR J0506-7025 is consistent with the standard -0.5 for supernova remnants. Radio polarisation at 6 cm indicates a higher degree of polarisation along the western front and at the eastern knot with a mean fractional polarisation across the remnant of P ≅ (20 ± 6)%. Conclusions: The detection of Fe-rich ejecta in the remnants suggests that both resulted from Type Ia explosions. The newly identified Fe-rich cores in MCSNR J0506-7025 and MCSNR J0527-7104 make them members of the expanding class of evolved Fe-rich remnants in the Magellanic Clouds

  20. Early cancer of the gastric remnant.

    PubMed Central

    Pointner, R; Schwab, G; Königsrainer, A; Bodner, E; Schmid, K W

    1988-01-01

    Early carcinoma of the gastric remnant was diagnosed in 19 patients between January 1976 and January 1986. In all patients early cancer was suspected at endoscopy and confirmed by biopsy and histology. The main reason for endoscopic examination was diffuse epigastric pain suggestive of stump gastritis. The surgical procedure was stump gastrectomy. Two of the 19 patients were not operated on because of advanced age. In contrast with the poor prognosis of patients with cancers of the gastric remnant of tumour stages T2 to T4 according to the TNM-classification regardless of their NM-stage, patients with tumour stage T1N0 and T1N1 have a good prognosis. PMID:3356360

  1. Supernova remnants in the GC region

    NASA Astrophysics Data System (ADS)

    Asvarov, Abdul

    2016-07-01

    Along with the central Black hole the processes of active star formation play very important role in the energetics of the Galactic center region. The SNe and their remnants (SNRs) are the main ingredients of the processes of star formation. SNRs are also the sources of electromagnetic radiation of all wavelengths from the optical to hard gamma rays. In the presented work we consider the physics of supernova remnants evolving in extreme environmental conditions which are typical for the region of the Galactic center. Because of the high density and strong inhomogeneity of the surrounding medium these objects remain practically invisible at almost all wavelengths. We model evolution of SNR taking into account the pressure of the surrounding medium and the gravitational field of the matter (stars, compact clouds, dark matter) inside the remnant. As it is well established, considerable portion of the kinetic energy of the SNR can be converted into the cosmic ray particles by diffusive shock acceleration mechanism. Therefore the effect of particle acceleration is also included in the model (with the effectiveness of acceleration as a free parameter). Using the observed radiation fluxes at different wavelengths we attempt to obtain limits on the parameters of the model of the Galactic Center, namely, the frequency of star birth, the average density of the matter and radiation field, etc.

  2. The First Fermi LAT Supernova Remnant Catalog

    NASA Astrophysics Data System (ADS)

    Acero, F.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen, J. M.; Cohen-Tanugi, J.; Cominsky, L. R.; Condon, B.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Ferrara, E. C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Hou, X.; Iafrate, G.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Laffon, H.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Magill, J.; Maldera, S.; Marelli, M.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Renaud, M.; Reposeur, T.; Rousseau, R.; Saz Parkinson, P. M.; Schmid, J.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Wells, B.; Wood, K. S.; Wood, M.; Yassine, M.; den Hartog, P. R.; Zimmer, S.

    2016-05-01

    To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed the first systematic survey at energies from 1 to 100 GeV using data from the Fermi Large Area Telescope (LAT). Based on the spatial overlap of sources detected at GeV energies with SNRs known from radio surveys, we classify 30 sources as likely GeV SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which the positions of known remnants are scrambled in Galactic longitude allows us to determine an upper limit of 22% on the number of GeV candidates falsely identified as SNRs. We have also developed a method to estimate spectral and spatial systematic errors arising from the diffuse interstellar emission model, a key component of all Galactic Fermi LAT analyses. By studying remnants uniformly in aggregate, we measure the GeV properties common to these objects and provide a crucial context for the detailed modeling of individual SNRs. Combining our GeV results with multiwavelength (MW) data, including radio, X-ray, and TeV, we demonstrate the need for improvements to previously sufficient, simple models describing the GeV and radio emission from these objects. We model the GeV and MW emission from SNRs in aggregate to constrain their maximal contribution to observed Galactic cosmic rays.

  3. The first Fermi LAT supernova remnant catalog

    DOE PAGES

    Acero, F.

    2016-05-16

    To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed the first systematic survey at energies from 1 to 100 GeV using data from the Fermi Large Area Telescope. Based on the spatial overlap of sources detected at GeV energies with SNRs known from radio surveys, we classify 30 sources as likely GeV SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which the positions of known remnants are scrambled in Galactic longitude, allows us to determine an upper limit of 22% on the number of GeV candidatesmore » falsely identified as SNRs. We have also developed a method to estimate spectral and spatial systematic errors arising from the diffuse interstellar emission model, a key component of all Galactic Fermi LAT analyses. By studying remnants uniformly in aggregate, we measure the GeV properties common to these objects and provide a crucial context for the detailed modeling of individual SNRs. Combining our GeV results with multiwavelength (MW) data, including radio, X-ray, and TeV, demonstrates the need for improvements to previously sufficient, simple models describing the GeV and radio emission from these objects. As a result, we model the GeV and MW emission from SNRs in aggregate to constrain their maximal contribution to observed Galactic cosmic rays.« less

  4. Syringomyelia caused by intrathecal remnants of oil-based contrast medium.

    PubMed

    Kubota, Mayumi; Shin, Masahiro; Taniguchi, Makoto; Terao, Toru; Nakauchi, Jun; Takahashi, Hiroshi

    2008-02-01

    Oily contrast medium had been in use since the early 19th century as a radiographic agent for detecting spinal lesions and spinal cord tumors until the late 20th century. At that point computed tomography scanning and magnetic resonance imaging, or other hydrophilic contrast medium substituted for it. Adverse effects of oil-based dye, both acute and chronic, had been reported since the middle of the 20th century. In this paper the authors report the case of syringomyelia that seemed to be caused mainly by remaining oily contrast medium for 44 years. Syringomyelia secondary to adhesive arachnoiditis caused by oily contrast medium after a long period of time is well known. In the present case, however, surgery revealed only mild arachnoiditis at the level of syringomyelia as well as both solid and liquid remnants of contrast medium. Generally, cerebrospinal fluid (CSF) blockage due to an arachnoid adhesion is considered to cause syringomyelia following adhesive arachnoiditis. The authors speculated that in the present case syringomyelia was induced by a mechanism different from that in the previously reported cases; the oily contrast medium itself seems to have induced the functional block of CSF and impaired the buffer system of the intrathecal pressure. No reports on thoracic adhesive arachnoiditis and syringomyelia caused by oil-based dye referred to this mechanism in reviewing the literature. PMID:18248289

  5. Shocked Clouds in the Vela Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Nichols, Joy S.; Slavin, Jonathan D.

    2004-01-01

    Unusually strong high-excitation C I has been detected in eleven lines of sight through the Vela supernova remnant by means of UV absorption-line studies of IUE data. Most of these lines of sight lie near the western edge of the X-ray bright region of the supernova remnant in a spatially distinct band approximately 1deg by 4deg oriented approximately north/south. The high-excitation C I (denoted C I*) is interpreted as evidence of a complex of shocked dense clouds inside the supernova remnant, due to the high pressures indicated in this region. To further analyze the properties of this region of C I*, we present new HIRES-processed IRAS data of the entire Vela SNR. A temperature map calculated from the HIRES IRAS data, based on a two-component dust model, reveals the signature of hot dust at several locations in the SNR. The hot dust is anti-correlated spatially with X-ray emission as revealed by ROSAT, as would be expected for a dusty medium interacting with a shock wave. The regions of hot dust are strongly correlated with optical filaments, supporting a scenario of dense clouds interior to the SNR that have been shocked and are now cooling behind the supernova blast wave. With few exceptions, the lines of sight to the strong C I* pass through regions of hot dust and optical filaments. Possible mechanisms for the production of the anomalously large columns of C I and C I* are discussed. Dense clouds on the back western hemisphere of the remnant may explain the relatively low X-ray emission in the western portion of the Vela supernova remnant due to the slower forward shock velocity in regions where the shock has encountered the dense clouds. An alternate explanation for the presence of neutral, excited state, and ionized species along the same line of sight may be a magnetic precusor that heats and compresses the gas ahead of the shock.

  6. Universal aspects of brittle fracture, adhesion, and atomic force microscopy

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1989-01-01

    This universal relation between binding energy and interatomic separation was originally discovered for adhesion at bimetallic interfaces involving the simple metals Al, Zn, Mg, and Na. It is shown here that the same universal relation extends to adhesion at transition-metal interfaces. Adhesive energies have been computed for the low-index interfaces of Al, Ni, Cu, Ag, Fe, and W, using the equivalent-crystal theory (ECT) and keeping the atoms in each semiinfinite slab fixed rigidly in their equilibrium positions. These adhesive energy curves can be scaled onto each other and onto the universal adhesion curve. The effect of tip shape on the adhesive forces in the atomic-force microscope (AFM) is studied by computing energies and forces using the ECT. While the details of the energy-distance and force-distance curves are sensitive to tip shape, all of these curves can be scaled onto the universal adhesion curve.

  7. PH dependent adhesive peptides

    DOEpatents

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  8. Cosmic ray acceleration at perpendicular shocks in supernova remnants

    SciTech Connect

    Ferrand, Gilles; Danos, Rebecca J.; Shalchi, Andreas; Safi-Harb, Samar; Edmon, Paul; Mendygral, Peter

    2014-09-10

    Supernova remnants (SNRs) are believed to accelerate particles up to high energies through the mechanism of diffusive shock acceleration (DSA). Except for direct plasma simulations, all modeling efforts must rely on a given form of the diffusion coefficient, a key parameter that embodies the interactions of energetic charged particles with magnetic turbulence. The so-called Bohm limit is commonly employed. In this paper, we revisit the question of acceleration at perpendicular shocks, by employing a realistic model of perpendicular diffusion. Our coefficient reduces to a power law in momentum for low momenta (of index α), but becomes independent of the particle momentum at high momenta (reaching a constant value κ{sub ∞} above some characteristic momentum p {sub c}). We first provide simple analytical expressions of the maximum momentum that can be reached at a given time with this coefficient. Then we perform time-dependent numerical simulations to investigate the shape of the particle distribution that can be obtained when the particle pressure back-reacts on the flow. We observe that for a given index α and injection level, the shock modifications are similar for different possible values of p {sub c}, whereas the particle spectra differ markedly. Of particular interest, low values of p {sub c} tend to remove the concavity once thought to be typical of non-linear DSA, and result in steep spectra, as required by recent high-energy observations of Galactic SNRs.

  9. Mini-review: barnacle adhesives and adhesion.

    PubMed

    Kamino, Kei

    2013-01-01

    Barnacles are intriguing, not only with respect to their importance as fouling organisms, but also in terms of the mechanism of underwater adhesion, which provides a platform for biomimetic and bioinspired research. These aspects have prompted questions regarding how adult barnacles attach to surfaces under water. The multidisciplinary and interdisciplinary nature of the studies makes an overview covering all aspects challenging. This mini-review, therefore, attempts to bring together aspects of the adhesion of adult barnacles by looking at the achievements of research focused on both fouling and adhesion. Biological and biochemical studies, which have been motivated mainly by understanding the nature of the adhesion, indicate that the molecular characteristics of barnacle adhesive are unique. However, it is apparent from recent advances in molecular techniques that much remains undiscovered regarding the complex event of underwater attachment. Barnacles attached to silicone-based elastomeric coatings have been studied widely, particularly with respect to fouling-release technology. The fact that barnacles fail to attach tenaciously to silicone coatings, combined with the fact that the mode of attachment to these substrata is different to that for most other materials, indicates that knowledge about the natural mechanism of barnacle attachment is still incomplete. Further research on barnacles will enable a more comprehensive understanding of both the process of attachment and the adhesives used. Results from such studies will have a strong impact on technology aimed at fouling prevention as well as adhesion science and engineering.

  10. Observing Supernovae and Supernova Remnants with JWST

    NASA Astrophysics Data System (ADS)

    Sonneborn, George; Temim, Tea; Williams, Brian J.; Blair, William P.

    2015-01-01

    The James Webb Space Telescope (JWST) will enable near- and mid-infrared studies of supernovae (SN) and supernova remnants (SNR) in the Milky Way and galaxies throughout the local universe and to high redshift. JWST's instrumentation provides imaging, coronography, and spectroscopy (R<3000) over the wavelength range 1-29 microns. The unprecedented sensitivity and angular resolution will enable spectroscopic study of new and recent supernovae, including molecule and dust formation, in galaxies at least out to 30 Mpc, and imaging to much greater distances. The Target of Opportunity response time can be as short as 48 hours, enabling quick follow-up observations of important SN events. JWST will be ideal for the study of Galactic and Magellanic Clouds supernova remnants, particularly young remnants with hot dust. Its high angular resolution (0.07" at 2 microns, 0.7" at 20 microns) will allow direct comparison between the IR, optical, and X-ray morphologies, identifying sites of dust emission in both the ejecta and the shocked ISM unresolved by previous IR telescopes. There is a rich spectrum of atomic lines (H, He I, [Si I], [Fe II], [Ni I-III], [Co II-III], [S III-IV], [Ar II-III], [Ne II, III, V], [O IV]) and molecules (CO, SiO, H2) of importance for SN and SNR studies. JWST is a large aperture (6.5m), cryogenic, infrared-optimized space observatory under construction by NASA, ESA, and CSA for launch in 2018. The JWST observatory will be placed in an Earth-Sun L2 orbit by an Ariane 5 launch vehicle provided by ESA. The observatory is designed for a 5-year prime science mission, with consumables for 10 years of science operations. The first call for proposals for JWST observations will be released in 2017.

  11. VHE Gamma-ray Supernova Remnants

    SciTech Connect

    Funk, Stefan; /KIPAC, Menlo Park

    2007-01-22

    Increasing observational evidence gathered especially in X-rays and {gamma}-rays during the course of the last few years support the notion that Supernova remnants (SNRs) are Galactic particle accelerators up to energies close to the ''knee'' in the energy spectrum of Cosmic rays. This review summarizes the current status of {gamma}-ray observations of SNRs. Shell-type as well as plerionic type SNRs are addressed and prospect for observations of these two source classes with the upcoming GLAST satellite in the energy regime above 100 MeV are given.

  12. Quantum remnants in the classical limit

    NASA Astrophysics Data System (ADS)

    Kowalski, A. M.; Plastino, A.

    2016-09-01

    We analyze here the common features of two dynamical regimes: a quantum and a classical one. We deal with a well known semi-classic system in its route towards the classical limit, together with its purely classic counterpart. We wish to ascertain i) whether some quantum remnants can be found in the classical limit and ii) the details of the quantum-classic transition. The so-called mutual information is the appropriate quantifier for this task. Additionally, we study the Bandt-Pompe's symbolic patterns that characterize dynamical time series (representative of the semi-classical system under scrutiny) in their evolution towards the classical limit.

  13. Excess gamma rays from the Loop I supernova remnant

    NASA Technical Reports Server (NTRS)

    Bhat, C. L.; Mayer, C. J.; Wolfendale, A. W.

    1985-01-01

    Evidence is presented for an excess of cosmic ray intensity within the Loop I supernova remnant based on an interpretation of the observed distribution of gamma-rays across the remnant and the column densities of the associated gas. A strong case can thus be made for the bulk of the cosmic radiation (E , 10 to the 11th power eV) being produced in the Galactic supernova remnants.

  14. Onion-shell model of cosmic ray acceleration in supernova remnants

    NASA Technical Reports Server (NTRS)

    Bogdan, T. J.; Volk, H. J.

    1983-01-01

    A method is devised to approximate the spatially averaged momentum distribution function for the accelerated particles at the end of the active lifetime of a supernova remnant. The analysis is confined to the test particle approximation and adiabatic losses are oversimplified, but unsteady shock motion, evolving shock strength, and non-uniform gas flow effects on the accelerated particle spectrum are included. Monoenergetic protons are injected at the shock front. It is found that the dominant effect on the resultant accelerated particle spectrum is a changing spectral index with shock strength. High energy particles are produced in early phases, and the resultant distribution function is a slowly varying power law over several orders of magnitude, independent of the specific details of the supernova remnant.

  15. X-ray characteristics of the Lupus Loop and SN 1006 supernova remnants

    SciTech Connect

    Toor, A.

    1980-01-01

    The spatial extent of the Lupus Loop and spectra for the Lupus Loop and SN1006 supernova remnants have been determined with a rocket-borne payload. The Lupus Loop is an extended source of soft X-rays (approx. 300' diam) that shows a correlation between its brightest x-ray and radio-emission regions. Its spectrum is characterized by a temperature of 350 eV. Thus, the Lupus Loop appears similar to Vela X and Cygnus Loop, although much weaker. Emission from SN1006 is spatially unresolved and exhibits a harder spectrum than that of the Lupus Loop. All spectral data (0.2 to 10 keV) from our observation and previous observations are satisfactorily fit with a power law (index = 2.15). This spectral dependence suggests the possibility that a rotating neutron star is the underlying source of the radiated energy although such an interpretation appears inconsistent with the remnant's morphology.

  16. FERMI LARGE AREA TELESCOPE DETECTION OF THE YOUNG SUPERNOVA REMNANT TYCHO

    SciTech Connect

    Giordano, F.; Naumann-Godo, M.; Ballet, J.; Mazziotta, M. N.; Raino, S.; Tibolla, O. E-mail: Melitta.Naumann-Godo@cea.fr

    2012-01-15

    After almost three years of data taking in sky-survey mode, the Fermi Large Area Telescope has detected {gamma}-ray emission toward Tycho's supernova remnant (SNR). The Tycho SNR is among the youngest remnants in the Galaxy, originating from a Type Ia Supernova in AD 1572. The {gamma}-ray integral flux from 400 MeV up to 100 GeV has been measured to be (3.5 {+-} 1.1{sub stat} {+-} 0.7{sub syst}) Multiplication-Sign 10{sup -9} cm{sup -2} s{sup -1} with a photon index of 2.3 {+-} 0.2{sub stat} {+-} 0.1{sub syst}. A simple model consistent with TeV, X-ray, and radio data is sufficient to explain the observed emission as originating from {pi}{sup 0} decays as a result of cosmic-ray acceleration and interaction with the ambient medium.

  17. Fermi Large Area Telescope Detection of the Young Supernova Remnant Tycho

    NASA Astrophysics Data System (ADS)

    Giordano, F.; Naumann-Godo, M.; Ballet, J.; Bechtol, K.; Funk, S.; Lande, J.; Mazziotta, M. N.; Rainò, S.; Tanaka, T.; Tibolla, O.; Uchiyama, Y.

    2012-01-01

    After almost three years of data taking in sky-survey mode, the Fermi Large Area Telescope has detected γ-ray emission toward Tycho's supernova remnant (SNR). The Tycho SNR is among the youngest remnants in the Galaxy, originating from a Type Ia Supernova in AD 1572. The γ-ray integral flux from 400 MeV up to 100 GeV has been measured to be (3.5 ± 1.1stat ± 0.7syst)× 10-9 cm-2 s-1 with a photon index of 2.3 ± 0.2stat ± 0.1syst. A simple model consistent with TeV, X-ray, and radio data is sufficient to explain the observed emission as originating from π0 decays as a result of cosmic-ray acceleration and interaction with the ambient medium.

  18. Tachyonic Cherenkov radiation from supernova remnants

    NASA Astrophysics Data System (ADS)

    Tomaschitz, Roman

    2015-12-01

    The subexponential decay observed in the γ-ray spectral maps of supernova remnants is explained in terms of tachyonic Cherenkov emission from a relativistic electron population. The tachyonic radiation densities of an electronic spinor current are derived, the total density as well as the transversal and longitudinal polarization components, taking account of electron recoil. Tachyonic flux quantization subject to dispersive and dissipative permeabilities is discussed, the matrix elements of the transversal and longitudinal Poynting vectors of the Maxwell-Proca field are obtained, Cherenkov emission angles and radiation conditions are derived. The spectral energy flux of an ultra-relativistic electron plasma is calculated, a tachyonic Cherenkov fit to the high-energy (1 GeV to 30 TeV) γ-ray spectrum of the Crab Nebula is performed, and estimates of the linear polarization degree are given. The spectral tail shows subexponential Weibull decay, which can be modeled with a frequency-dependent tachyon mass in the dispersion relations. Tachyonic flux densities interpolate between exponential and power-law spectral decay, which is further illustrated by Cherenkov fits to the γ-ray spectra of the supernova remnants IC 443 and W44. Subexponential spectral decay is manifested in double-logarithmic spectral maps as curved Weibull or straight power-law slope.

  19. Color Composite Image of the Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image is a color composite of the supernova remnant E0102-72: x-ray (blue), optical (green), and radio (red). E0102-72 is the remnant of a star that exploded in a nearby galaxy known as the Small Magellanic Cloud. The star exploded outward at speeds in excess of 20 million kilometers per hour (12 million mph) and collided with surrounding gas. This collision produced two shock waves, or cosmic sonic booms, one traveling outward, and the other rebounding back into the material ejected by the explosion. The radio image, shown in red, was made using the Australia Telescope Compact Array. The radio waves are due to extremely high-energy electrons spiraling around magnetic field lines in the gas and trace the outward moving shock wave. The Chandra X-ray Observatory image, shown in blue, shows gas that has been heated to millions of degrees by the rebounding, or reverse shock wave. The x-ray data show that this gas is rich in oxygen and neon. These elements were created by nuclear reactions inside the star and hurled into space by the supernova. The Hubble Space Telescope optical image, shown in green, shows dense clumps of oxygen gas that have 'cooled' to about 30,000 degrees. Photo Credit: X-ray (NASA/CXC/SAO); optical (NASA/HST): radio: (ACTA)

  20. Ruprecht 3: An old star cluster remnant?

    NASA Astrophysics Data System (ADS)

    Pavani, D. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2003-02-01

    2MASS J and H photometry and integrated spectroscopy are employed to study the nature of the poorly populated compact concentration of stars Ruprecht 3, which was previously catalogued as an open cluster. The integrated spectrum remarkably resembles that of a moderately metal-rich globular cluster. The distribution of the object stars in the colour-magnitude diagram is compatible with that of a 1.5 +/- 0.5 Gyr open cluster or older, depending on whether the bluer stars are interpreted as turnoff stars or blue stragglers, respectively. We derive for the object a distance from the Sun dsun = 0.72 +0.04-0.03 kpc and a colour excess E(B-V) = 0.04. Although a globular cluster remnant cannot be ruled out, the integrated spectrum resemblance to that of a globular cluster probably reflects a stochastic effect owing to the few brighter stars. The structural and photometric properties of Ruprecht 3 are compatible with what would be expected for an intermediate-age open cluster remnant. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  1. A kinematic study of Tycho's supernova remnant

    NASA Astrophysics Data System (ADS)

    Hughes, P. J.; Sato, T.

    2016-06-01

    Thanks to its confirmed nature as the remnant of a standard Type Ia supernova from spectroscopy of its light echo, Tycho's supernova remnant is a unique object that can provide a new perspective into thermonuclear supernova explosions. More than 400 years after its discovery as a supernova in November 1572, the remnant is now spread out over an 8 arcminute diameter region in a fairly symmetric, but patchy, shell-like morphology. The remnant's thermal X-ray emission is dominated by a strong Si Kalpha line and also shows line emission from other species such as S, Ar, Ca, and Fe. Existing proper motion and X-ray line width measurements indicate that Tycho's Si-rich ejecta shell is expanding at ~4700 km/s. We have taken advantage of the huge number of Si line photons in the 750-ks Chandra ACIS observation from 2009 to make the first direct velocity measurements of ejecta in Tycho. The patchy nature of the ejecta shell allows for identification of red- and blue-shifted clumps of emission from the receding and approaching hemispheres. We use nonequilibrium ionization thermal models to jointly fit both ACIS-S and ACIS-I observations to determine the radial expansion velocity of individual clumps and associated systematic uncertainty. Red-shifted clumps have speeds of 3500-7800 km/s and blue-shifted clumps 1600--5000 km/s with a systematic uncertainty of 500-2000 km/s determined by intercomparison of the ACIS-S and ACIS-I spectral results. From our Chandra radial analysis of surface brightness, centroid energy, and line width, we have confirmed previous line width measurements from Suzaku, but are able to utilize finer radial bins that reveal additional structure in the kinematics of Tycho. In particular the Si and S line widths reach a deep minimum at the position of the peak surface brightness near the remnant's edge and where Doppler broadening from the shell expansion is minimum. From the measured line widths and assuming that Doppler and turbulent broadening can be

  2. Adhesion at metal interfaces

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1991-01-01

    A basic adhesion process is defined, the theory of the properties influencing metallic adhesion is outlined, and theoretical approaches to the interface problem are presented, with emphasis on first-principle calculations as well as jellium-model calculations. The computation of the energies of adhesion as a function of the interfacial separation is performed; fully three-dimensional calculations are presented, and universality in the shapes of the binding energy curves is considered. An embedded-atom method and equivalent-crystal theory are covered in the framework of issues involved in practical adhesion.

  3. Gecko adhesion: evolutionary nanotechnology.

    PubMed

    Autumn, Kellar; Gravish, Nick

    2008-05-13

    If geckos had not evolved, it is possible that humans would never have invented adhesive nanostructures. Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1ms-1. Climbing presents a significant challenge for an adhesive in requiring both strong attachment and easy rapid removal. Conventional pressure-sensitive adhesives (PSAs) are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). The gecko adhesive differs dramatically from conventional adhesives. Conventional PSAs are soft viscoelastic polymers that degrade, foul, self-adhere and attach accidentally to inappropriate surfaces. In contrast, gecko toes bear angled arrays of branched, hair-like setae formed from stiff, hydrophobic keratin that act as a bed of angled springs with similar effective elastic modulus to that of PSAs. Setae are self-cleaning and maintain function for months during repeated use in dirty conditions. Setae are an anisotropic 'frictional adhesive' in that adhesion requires maintenance of a proximally directed shear load, enabling either a tough bond or spontaneous detachment. Gecko-like synthetic adhesives may become the glue of the future-and perhaps the screw of the future as well.

  4. Electro-dry-adhesion.

    PubMed

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample.

  5. Electro-dry-adhesion.

    PubMed

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample. PMID:22397643

  6. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  7. Effect of surface treatment of brackets and mechanical cycling on adhesion to enamel.

    PubMed

    Arrais, Fabiola Rossato; Degrazia, Felipe; Peres, Bernardo Urbanetto; Ferrazzo, Vilmar Antonio; Grehs, Renesio Armindo; Valandro, Luiz Felipe

    2014-01-01

    This in vitro study sought to evaluate how surface conditioning from bracket and mechanical cycling aging affected the bond strength between metallic brackets and bovine enamel, and to determine the adhesive remnant index. Eighty bovine incisors were embedded in acrylic resin using polyvinyl chloride rings and divided into 4 groups based on surface treatment (n = 20). Group 1 (control) received no surface treatment, Group 2 specimens were sandblasted with aluminum oxide particles, Group 3 specimens were sandblasted with silicon oxide and treated with a tribochemichemical silica coupling agent, and Group 4 specimens were primed with a multidomain protein-based agent. Half of the specimens were submitted to shear bond testing, while the others were subjected to mechanical cycling. ANOVA showed that mechanical cycling did not have a significant influence on bond strength (P = 0.9244), while surface conditioning of the brackets did (P = 0.0001). Tukey's test results were similar for mechanical cycling, and indicated that only Group 3 significantly improved the resin bond to the brackets; however, this group also demonstrated the highest percentage of enamel failure. PMID:24784526

  8. Limitations of automated remnant lipoprotein cholesterol assay for diagnostic use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    I wish to comment on the limitations of automated remnant lipoprotein cholesterol (RemL-C) assay reported in Clinical Chemistry. Remnants are lipoprotein particles produced after newly formed triglyceride-rich lipoproteins (TRLs) of either hepatic or intestinal origin enter the plasma space and unde...

  9. The likely Fermi detection of the supernova remnant RCW 103

    SciTech Connect

    Xing, Yi; Wang, Zhongxiang; Zhang, Xiao; Chen, Yang

    2014-02-01

    We report on the results from our γ-ray analysis of the supernova remnant (SNR) RCW 103 region. The data were taken with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. An extended source is found at a position consistent with that of RCW 103 and its emission was only detected above 1 GeV (10σ significance), with a power-law spectrum with a photon index of 2.0 ± 0.1. We obtain its 1-300 GeV spectrum and the total flux gives a luminosity of 8.3 × 10{sup 33} erg s{sup –1} at a source distance of 3.3 kpc. Given the positional coincidence and property similarities of this source with other SNRs, we identify it as the likely Fermi γ-ray counterpart to RCW 103. Including radio measurements of RCW 103, the spectral energy distribution (SED) is modeled by considering emission mechanisms based on both hadronic and leptonic scenarios. We find that models in the two scenarios can reproduce the observed SED, while in the hadronic scenario the existence of SNR-molecular cloud interactions is suggested as a high density of the target protons is required.

  10. A comparison of tungsten-quartz-halogen, plasma arc and light-emitting diode light sources for the polymerization of an orthodontic adhesive.

    PubMed

    Thind, Bikram S; Stirrups, David R; Lloyd, Charles H

    2006-02-01

    This study investigated whether there were differences between the debond stress and adhesive remnant index (ARI) of an adhesive cured with three different orthodontic light sources. Sixty sound premolar teeth were divided into three groups of 20. A standard pre-adjusted edgewise premolar bracket (Victory Series) was bonded to each tooth using a light-cured orthodontic adhesive, Transbond X. Group 1 (control) specimens were cured with an Ortholux XT (tungsten-quartz-halogen bulb) light for 20 seconds, group 2 with an Ortho lite (plasma arc) for 6 seconds and group 3 with an Ortholux LED light-emitting diode for 10 seconds. The specimens were debonded 24 hours later using a universal mechanical testing machine, operating at a crosshead speed of 0.5 mm minute(-1). The Weibull modulus and a Logrank test showed no statistically significant differences between the three groups for debond stress. The ARI was assessed at x10 magnification. The ARI scores for group 2 were significantly different (P < 0.01) from those of groups 1 and 3 (between which there was no significant difference). For group 2 there was a greater tendency for failure to occur at the adhesive/tooth interface than for the other two groups. There appears to be no reason why any of the three types of light source cannot be used in orthodontics. Polymerization, as effective as that produced by conventional bulb light sources, was obtained with the short exposure times recommended for the plasma arc or light-emitting diode sources. PMID:16199410

  11. Multi-Wavelength Observations of Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Williams, B.

    2012-01-01

    Supernova remnants (SNRs) provide a laboratory for studying various astrophysical processes, including particle acceleration, thermal and non thermal emission processes across the spectrum, distribution of heavy elements, the physics of strong shock waves, and the progenitor systems and environments of supernovae. Long studied in radio and X-rays, the past decade has seen a dramatic increase in the detection and subsequent study of SNRs in the infrared and gamma-ray regimes. Understanding the evolution of SNRs and their interaction with the interstellar medium requires a multi-wavelength approach. I will review the various physical processes observed in SNRs and how these processes are intertwined. In particular, I will focus on X-ray and infrared observations, which probe two very different but intrinsically connected phases of the ISM: gas and dust. I will discuss results from multi-wavelength studies of several SNRs at various stages of evolution, including Kepler, RCW 86, and the Cygnus Loop.

  12. Vivid View of Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This composite image of the Tycho supernova remnant combines infrared and X-ray observations obtained with NASA's Spitzer and Chandra space observatories, respectively, and the Calar Alto observatory, Spain. It shows the scene more than four centuries after the brilliant star explosion witnessed by Tycho Brahe and other astronomers of that era.

    The explosion has left a blazing hot cloud of expanding debris (green and yellow). The location of the blast's outer shock wave can be seen as a blue sphere of ultra-energetic electrons. Newly synthesized dust in the ejected material and heated pre-existing dust from the area around the supernova radiate at infrared wavelengths of 24 microns (red). Foreground and background stars in the image are white.

  13. Semiclassical geons as solitonic black hole remnants

    SciTech Connect

    Lobo, Francisco S.N.; Olmo, Gonzalo J.; Rubiera-Garcia, D. E-mail: gonzalo.olmo@csic.es

    2013-07-01

    We find that the end state of black hole evaporation could be represented by non-singular and without event horizon stable solitonic remnants with masses of the order the Planck scale and up to ∼ 16 units of charge. Though these objects are locally indistinguishable from spherically symmetric, massive electric (or magnetic) charges, they turn out to be sourceless geons containing a wormhole generated by the electromagnetic field. Our results are obtained by interpreting semiclassical corrections to Einstein's theory in the first-order (Palatini) formalism, which yields second-order equations and avoids the instabilities of the usual (metric) formulation of quadratic gravity. We also discuss the potential relevance of these solutions for primordial black holes and the dark matter problem.

  14. Resolved structure in M33 supernova remnants

    NASA Technical Reports Server (NTRS)

    Blair, William P.; Davidsen, Arthur F.

    1993-01-01

    We present WF/PC narrow band forbidden S II 6725-wavelength images of two M33 supernova remnants obtained with the Wide Field/Planetary Camera on the HST. Comparison of these images with ground-based CCD data indicates that HST has resolved the nebular structures into shells or partial shells, permitting improved measurements of the diameters of these objects. Ground-based echelle spectra obtained at Kitt Peak with the 4-m telescope show profiles with half-width zero-intensity velocities of 163 and 275 km/sec for the two objects, indicating rapid bulk motions of the emitting filaments. The morphology of the emission seen in the WF/PC images allows the non-Gaussian shapes of the integrated echelle profiles to be understood. We briefly compare the predicted WF/PC count rates with those actually realized and discuss the reason for the discrepancy.

  15. Self similar evolution of evaporative supernova remnants

    NASA Astrophysics Data System (ADS)

    Chieze, J. P.; Lazareff, B.

    1981-02-01

    The expansion of a supernova remnant into an inhomogeneous medium of evaporating clouds can be idealized as a self-similar problem. The equations are set up and solved in the two limiting cases of negligible and dominant large scale conductivity, in the presence of an ad hoc external intercloud density equal to the product of Gamma, a parameter dependent on the evaporation parameter and the energy deposited by the supernova, with the -5/3 power of the radial distance, with Gamma equals 0 as a limiting case. While the detailed structure depends on Gamma, the global properties such as the expansion law and the total mass are to a large extent independent of this parameter, and agree with previous approximate results of McKee and Ostriker (1977). The limitations of the formal solutions are briefly discussed.

  16. Radio flux variation of young supernova remnants

    SciTech Connect

    Ivanov, V.P.; Bubukin, I.T.; Stankevich, K.S.

    1982-01-01

    The 31.5-cm radio flux density of Cas A, the Crab Nebula, and the remnant of the 1572 supernova relative to that of the radio galaxies Cyg A and Vir A was measured in 1981. Comparison with similar observations in 1964 and 1972 shows that over the past decade the decline of the Cas A flux has slowed by a factor 2.2 and now amounts to (0.413 +- 0.08)%/yr. The Crab flux was (3.5 +- 1.0)% weaker in 1981 than in 1964 and 1972; it probably dropped abruptly between 1972 and 1977. For the 1572 SNR the annual mean decline over the 17-yr period is (0.5 +- 0.15)%/yr.

  17. Remnants of Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Lopez, Laura

    2015-04-01

    Supernovae (SNe) play an essential role in the Universe, and they are detected routinely through dedicated surveys. However, most of these SNe are often too distant (~1-100 Mpc) to resolve the SN ejecta and immediate surroundings of the exploded stars. Fortunately, supernova remnants (SNRs) offer the means to study explosions and dynamics at sub-pc scales. SNRs are observable for up to 105 years after the explosions across the electromagnetic spectrum, and almost 400 SNRs have now been identified in the Milky Way and nearby galaxies. In this talk, I will review recent advances in the understanding of core-collapse (CC) SNe based on studies of SNRs. In particular, I will highlight investigations of SNR (a)symmetry and of heavy metal (like iron and titanium) abundances which give insight to the nature and mechanisms of the originating explosions.

  18. Black hole remnant from gravity's rainbow

    NASA Astrophysics Data System (ADS)

    Farag Ali, Ahmed

    2014-05-01

    In this work, we investigate black hole (BH) physics in the context of the gravity rainbow. We investigate this through rainbow functions that have been proposed by Amelino-Camelia [Living Rev. Relativity 16, 5 (2013)] and Amelino-Camelia et al. in [Int. J. Mod. Phys. A 12, 607 (1997)]. This modification will give corrections to both the temperature and the entropy of BHs, and hence it changes the picture of Hawking radiation greatly when the size of the BH approaches the Planck scale. It prevents the BH from total evaporation, predicting the existence of a BH remnant, which may resolve the catastrophic behavior of Hawking radiation as the BH mass approaches zero.

  19. The Remnant of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    McCray, Richard; Fransson, Claes

    2016-09-01

    Although it has faded by a factor of ˜107, SN 1987A is still bright enough to be observed in almost every band of the electromagnetic spectrum. Today, the bolometric luminosity of the debris is dominated by a far-infrared (˜200μm) continuum from ˜0.5 M⊙ of dust grains in the interior debris. The dust is heated by UV, optical, and near-infrared (NIR) emission resulting from radioactive energy deposition by 44Ti. The optical light of the supernova debris is now dominated by illumination of the debris by X-rays resulting from the impact of the outer supernova envelope with an equatorial ring (ER) of gas that was expelled some 20,000 years before the supernova explosion. X-ray and optical observations trace a complex system of shocks resulting from this impact, whereas radio observations trace synchrotron radiation from relativistic electrons accelerated by these shocks. The luminosity of the remnant is dominated by an NIR (˜20μm) continuum from dust grains in the ER heated by collisions with ions in the X-ray emitting gas. With the Atacama Large Millimeter Array (ALMA), we can observe the interior debris at millimeter/submillimeter wavelengths, which are not absorbed by the interior dust. The ALMA observations reveal bright emission lines from rotational transitions of CO and SiO lines that provide a new window into the interior structure of the supernova debris. Optical, NIR, and ALMA observations all indicate strongly asymmetric ejecta. Intensive searches have failed to yield any evidence for the compact object expected to reside at the center of the remnant. The current upper limit to the luminosity of such an object is a few tens of solar luminosities.

  20. Neuron adhesion and strengthening

    NASA Astrophysics Data System (ADS)

    Rocha, Aracely; Jian, Kuihuan; Ko, Gladys; Liang, Hong

    2010-07-01

    Understanding the neuron/material adhesion is important for neuron stimulation and growth. The current challenges remain in the lack of precision of measuring techniques and understanding the behavior of neuron. Here, we report a fluid shear method to investigate adhesion at the neuron/poly-D-lysine interface. In this study, the adhesion of 12-day-old chick embryo-retina neurons cultured on poly-D-lysine coated glass coverslips was measured via parallel disk rotational flow. The shear stress experienced by the cells increases with the disk radius. There is a critical point along the radius (Rc) where the stress experienced by the neurons equals their adhesion. The measured Rc can be used to calculate the neuron adhesion. Our results demonstrate that neurons adhered to the poly-D-lysine had a strain hardening effect. The adhesive shear stress of the neuron-material increased with applied shear (τa). When the τa reached or exceeded the value of 40 dyn/cm2, the adhesion remained constant at approximately 30 dyn/cm2. The present work allowed us not only to quantify the adhesive strength and force but also to evaluate the value of strain hardening at the neuron/poly-D-lysine interface.

  1. Postoperative Peritoneal Adhesions

    PubMed Central

    Ryan, Graeme B.; Grobéty, Jocelyne; Majno, Guido

    1971-01-01

    This paper describes an experimental model of peritoneal adhesions, in the rat, based on two relatively minor accidents that may occur during abdominal surgery in man: drying of the serosa, and bleeding. Drying alone had little effect; drying plus bleeding consistently produced adhesions to the dried area. Fresh blood alone produced adhesions between the three membranous structures [omentum and pelvic fat bodies (PFBs)]. The formation of persistent adhesions required whole blood. Preformed clots above a critical size induced adhesions even without previous serosal injury; they were usually captured by the omentum and PFBs. If all three membranous structures were excised, the clots caused visceral adhesions. The protective role of the omentum, its structure, and the mechanism of omental adhesions, are discussed. These findings are relevant to the pathogenesis of post-operative adhesions in man. ImagesFig 3Fig 4Fig 5Fig 6Fig 7Fig 12Fig 13Fig 1Fig 2Fig 14Fig 15Fig 8Fig 9Fig 10Fig 11 PMID:5315369

  2. Instant acting adhesive system

    NASA Technical Reports Server (NTRS)

    Davis, T. R.; Haines, R. C.

    1971-01-01

    Adhesive developes 80 percent of minimum bond strength of 250 psi less than 30 sec after activation is required. Adhesive is stable, handles easily, is a low toxic hazard, and is useful in industrial and domestic prototype bonding and clamping operations.

  3. Fermi-Lat and WMAP Observations of the Puppis a Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Hewitt, John William; Grondin, M. H.; Lemoine-Goumard, M.; Reposeur, T.; Ballet, J.; Tanaka, T.

    2012-01-01

    We report the detection of GeV gamma-ray emission from the supernova remnant Puppis A with the Fermi Gamma-Ray Space Telescope. Puppis A is among the faintest supernova remnants yet detected at GeV energies, with a luminosity of only 2.7×10(exp 34) (D/2.2 kpc)(exp 2) erg s(exp -1) between 1 and 100 GeV. The gamma-ray emission from the remnant is spatially extended, with a morphology matching that of the radio and X-ray emission, and is well described by a simple power law with an index of 2.1. We attempt to model the broadband spectral energy distribution, from radio to gamma-rays, using standard nonthermal emission mechanisms. To constrain the relativistic electron population we use 7 years of WMAP data to extend the radio spectrum up to 93 GHz. Both leptonic and hadronic dominated models can reproduce the nonthermal spectral energy distribution, requiring a total content of cosmic ray (CR) electrons and protons accelerated in Puppis A of at least WCR is approx. (1 - 5)×10 (exp 49) erg.

  4. Modelling the interaction of thermonuclear supernova remnants with circumstellar structures: the case of Tycho's supernova remnant

    NASA Astrophysics Data System (ADS)

    Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.; Kaastra, J. S.

    2013-10-01

    The well-established Type Ia remnant of Tycho's supernova (SN 1572) reveals discrepant ambient medium-density estimates based on either the measured dynamics or the X-ray emission properties. This discrepancy can potentially be solved by assuming that the supernova remnant (SNR) shock initially moved through a stellar wind bubble, but is currently evolving in the uniform interstellar medium with a relatively low density. We investigate this scenario by combining hydrodynamical simulations of the wind-loss phase and the SNR evolution with a coupled X-ray emission model, which includes non-equilibrium ionization. For the explosion models we use the well-known W7 deflagration model and the delayed detonation model that was previously shown to provide good fits to the X-ray emission of Tycho's SNR. Our simulations confirm that a uniform ambient density cannot simultaneously reproduce the dynamical and X-ray emission properties of Tycho. In contrast, models that considered that the remnant was evolving in a dense, but small, wind bubble reproduce reasonably well both the measured X-ray emission spectrum and the expansion parameter of Tycho's SNR. Finally, we discuss possible mass-loss scenarios in the context of single- and double-degenerate models which possibly could form such a small dense wind bubble.

  5. Indexing Images.

    ERIC Educational Resources Information Center

    Rasmussen, Edie M.

    1997-01-01

    Focuses on access to digital image collections by means of manual and automatic indexing. Contains six sections: (1) Studies of Image Systems and their Use; (2) Approaches to Indexing Images; (3) Image Attributes; (4) Concept-Based Indexing; (5) Content-Based Indexing; and (6) Browsing in Image Retrieval. Contains 105 references. (AEF)

  6. Adhesives in larynx repair.

    PubMed

    Lyons, M B; Lyons, G D; Webster, D; Wheeler, V R

    1989-04-01

    Guinea pig laryngeal fractures were used as a model to compare the ease of application and effectiveness of the fibrinogen-adhesive system with the ease of application and effectiveness of cyanoacrylate glue and control fractures stinted with contralateral gelatin film. Seven fibrin adhesive-treated and two cyanoacrylate glue-treated guinea pigs were perfused after 60 and 35 days, respectively. The larynges were serial sectioned, and the wound sites were compared. The fibrinogen adhesive system was easier to dispense than cyanoacrylate glue, did not require a completely dry surface, and stabilized within 3 minutes. Cartilage segment alignment with focal, complete fracture healing and symmetrical chondrocyte proliferation were seen in fibrogen adhesive-stinted larynges. In the cyanoacrylate glue-treated larynges, there was no alignment and minimal, asymmetrical chondrocyte proliferation. Gelatin film-stinted controls exhibited similar features. Thus, fibrogen adhesive was easier to apply and more effectively bound laryngeal fractures than cyanoacrylate glue or gelatin film.

  7. VLA observations of the supernova remnant Puppus A at 327 and 1515 MHz

    NASA Technical Reports Server (NTRS)

    Dubner, G. M.; Braun, R.; Winkler, P. F.; Goss, W. M.

    1991-01-01

    Very Large Array radio images of Puppis A at 327 and 1515 MHz are presented. The observations were performed with the VLA in the C/D and B/C configurations, respectively. The angular resolution is about 77 arcsec x 43 arcsec. The observed radio shell shows signs of interaction between the expanding shock front and the inhomogeneous surrounding medium. An excellent correlation is found between radio and X-ray emission, mainly toward the NE border of the remnant. There is little correspondence between the optical and radio images, suggesting a different origin for the emission. A region of steeper radio spectral index is associated with the highly decelerated eastern periphery.

  8. Cytotoxicity of denture adhesives.

    PubMed

    de Gomes, Pedro Sousa; Figueiral, Maria Helena; Fernandes, Maria Helena R; Scully, Crispian

    2011-12-01

    Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles.

  9. Characterization of chylomicron remnant binding to rat liver membranes.

    PubMed

    Cooper, A D; Erickson, S K; Nutik, R; Shrewsbury, M A

    1982-01-01

    The binding of chylomicron remnants to rat liver membranes was investigated using radioiodinated lipoproteins. The specific activity of binding increased in parallel with increased enrichment in plasma membrane markers. The yield of receptor activity, however, decreased with enrichment. Accordingly, a partially purified plasma membrane preparation was used for routine studies. Binding was saturable, with half maximal binding achieved at 4.6 micro g tetramethylurea-precipitable protein per ml. The rate of binding was time- and temperature-dependent. It could be inhibited only moderately by 10 mM EDTA. Chylomicron remnants appeared to bind to the membrane as a unit. The bound particle was richer in apoproteins of 20,000-50,000 molecular weight relative to low molecular weight apoproteins than the particles that were not bound. Lipoprotein particles containing only human apoB did not bind to liver membranes nor did they compete for the remnant binding site. Rat lipoproteins of d 1.019-1.063 g/ml did compete for remnant binding. When they were separated into apoB-rich (LDL) or apoE-rich (HDL(c)) fractions by block electrophoresis, the apoE-rich fraction was a more potent competitor. ApoE purified and reconstituted into dimyristoyl phosphatidylcholine vesicles was a potent competitor for the remnant binding site. Vesicles containing (125)I-labeled apoE bound to the membranes, and they could be displaced by unlabeled remnants. Dimyristoyl phosphatidylcholine vesicles themselves did not compete with either remnants or apoE-phospholipid vesicles. These results offer strong support for the hypothesis that the liver membrane chylomicron remnant receptor recognizes apoE with a high affinity, and this initiates the rapid removal of lipoproteins that contain this apoprotein.-Cooper, A. D., S. K. Erickson, R. Nutik, and M. A. Shrewsbury. Characterization of chylomicron remnant binding to rat liver membranes.

  10. Three Great Eyes on Kepler's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Composite

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Chandra X-Ray Data (blue) Chandra X-Ray Data (green)Hubble Telescope (visible-light)Spitzer Telescope (infrared)

    NASA's three Great Observatories -- the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory -- joined forces to probe the expanding remains of a supernova, called Kepler's supernova remnant, first seen 400 years ago by sky watchers, including astronomer Johannes Kepler.

    The combined image unveils a bubble-shaped shroud of gas and dust that is 14 light-years wide and is expanding at 4 million miles per hour (2,000 kilometers per second). Observations from each telescope highlight distinct features of the supernova remnant, a fast-moving shell of iron-rich material from the exploded star, surrounded by an expanding shock wave that is sweeping up interstellar gas and dust.

    Each color in this image represents a different region of the electromagnetic spectrum, from X-rays to infrared light. These diverse colors are shown in the panel of photographs below the composite image. The X-ray and infrared data cannot be seen with the human eye. By color-coding those data and combining them with Hubble's visible-light view, astronomers are presenting a more complete picture of the supernova remnant.

    Visible-light images from the Hubble telescope (colored yellow) reveal where the supernova shock wave is slamming into the densest regions of surrounding gas. The bright glowing knots are dense clumps from instabilities that form behind the shock wave. The Hubble data also show thin filaments of gas that look like rippled sheets seen edge-on. These filaments reveal where the shock wave is encountering lower-density, more uniform interstellar material.

    The Spitzer telescope shows microscopic dust particles (colored red) that have been heated by the

  11. [Endothelial cell adhesion molecules].

    PubMed

    Ivanov, A N; Norkin, I A; Puchin'ian, D M; Shirokov, V Iu; Zhdanova, O Iu

    2014-01-01

    The review presents current data concerning the functional role of endothelial cell adhesion molecules belonging to different structural families: integrins, selectins, cadherins, and the immunoglobulin super-family. In this manuscript the regulatory mechanisms and factors of adhesion molecules expression and distribution on the surface of endothelial cells are discussed. The data presented reveal the importance of adhesion molecules in the regulation of structural and functional state of endothelial cells in normal conditions and in pathology. Particular attention is paid to the importance of these molecules in the processes of physiological and pathological angiogenesis, regulation of permeability of the endothelial barrier and cell transmigration.

  12. Focal adhesions in osteoneogenesis

    PubMed Central

    Biggs, M.J.P; Dalby, M.J

    2010-01-01

    As materials technology and the field of tissue engineering advances, the role of cellular adhesive mechanisms, in particular the interactions with implantable devices, becomes more relevant in both research and clinical practice. A key tenet of medical device technology is to use the exquisite ability of biological systems to respond to the material surface or chemical stimuli in order to help develop next-generation biomaterials. The focus of this review is on recent studies and developments concerning focal adhesion formation in osteoneogenesis, with an emphasis on the influence of synthetic constructs on integrin mediated cellular adhesion and function. PMID:21287830

  13. Cell adhesion force microscopy

    PubMed Central

    Sagvolden, G.; Giaever, I.; Pettersen, E. O.; Feder, J.

    1999-01-01

    The adhesion forces of cervical carcinoma cells in tissue culture were measured by using the manipulation force microscope, a novel atomic force microscope. The forces were studied as a function of time and temperature for cells cultured on hydrophilic and hydrophobic polystyrene substrates with preadsorbed proteins. The cells attached faster and stronger at 37°C than at 23°C and better on hydrophilic than on hydrophobic substrates, even though proteins adsorb much better to the hydrophobic substrates. Because cell adhesion serves to control several stages in the cell cycle, we anticipate that the manipulation force microscope can help clarify some cell-adhesion related issues. PMID:9892657

  14. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  15. The Formation and Evolution of Mixed Morphology Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Smith, Randall

    Supernovae inject metals at high velocities into the interstellar medium (ISM), leading to shocks, plasma heating, and dust destruction and creation in addition to host of other processes. Supernova remnants (SNR) themselves are generally categorized as shell-type, center-filled, or ``mixed morphology.'' These categories, which encapsulate both the structure and evolution of the remnant, seem to depend critically on the precursor star and the surrounding ISM. Mixed morphology remnants, in particular, show a radio shell with a central region that emits primarily thermal X-rays. Observations show that these SNR are typically found near or in molecular clouds and, since they usually contain compact objects, arise from high-mass precursors. However, our theoretical understanding of these remnants lags far behind our observational data. There are at least four distinct models for their appearance, usually explaining observations from one or at most a few of the remnants, but there is no general solution. However, there has been a recent breakthrough in mixed morphology remnants. Suzaku observations of three remnants show that a significant fraction of the thermal X-rays are from a non-equilibrium recombining plasma, a surprising result since SNR are expected to generate ionizing, not recombining, plasmas. This new discovery should severely constrains theoretical predictions. We propose a combined semi-analytic and computational approach to understanding how these remnants develop and evolve. A number of observational studies have already cataloged the emission characteristics and sizes of these remnants. Our study will therefore begin with an exploration of simple 1-D spherically symmetric hydrodynamic plasma models that can generate the observed emission in X-ray and other bandpasses as well as the approximate size of a range of mixed morphology remnants. We will expand these studies using both 2-D and 3-D magnetohydrodynamic explosion models combined with a non

  16. Electron acceleration by young supernova remnant blast waves

    NASA Technical Reports Server (NTRS)

    Blandford, R. D.

    1992-01-01

    Some general considerations regarding relativistic particle acceleration by young supernova remnants are reviewed. Recent radio observations of supernova remnants apparently locate the bounding shock and exhibit large electron density gradients which verify the presence of strong particle scattering. The radio 'rim' in Tycho's remnant has been found to contain a predominantly radial magnetic field. This may be attributable to an instability of the shock surface and a progress report on an investigation of the stability of strong shocks in partially ionized media is presented.

  17. Distribution of supernova remnants in the Large Magellanic Cloud

    SciTech Connect

    Forest, T.A.; Spenny, D.L.; Johnson, R.W.

    1988-06-01

    The distribution of SNRs in the LMC may provide some insight concerning the classification of those remnants as Type I or Type II. The distance between each SNR and its nearest H II region was calculated, and the average of these distances was compared to the corresponding value that would be expected if the SNRs were randomly distributed in the LMC. A statistical analysis suggests that the SNRs are closer to H II regions than if the remnants were distributed randomly. Thus, there seems to be an association between SNRs and H II regions which suggests a preponderance of Type II remnants in the LMC. 7 references.

  18. Investigation of the Nebular Remnants of Novae

    NASA Astrophysics Data System (ADS)

    Ribeiro, Valério A. R. M.

    2011-01-01

    Classical and recurrent nova outbursts occur on the surface of a white dwarf in a close binary system. It is widely established that the outburst is due to a thermonuclear runaway. Their study provides a real-time laboratory for the understanding of a wide range of astrophysical phenomena. These include for example, mass transfer in close binary systems, nuclear powered outbursts, dust formation, mass loss from red giants, and many others. Recurrent novae have also been suggested as the progenitors of Type Ia Supernovae. This thesis concentrates on investigating the nebular remnants of novae by studying both resolved imaging (where available) and spectroscopic evolution and combining this with detailed modelling. Such studies have wider implications for example in our understanding of the shaping of proto-Planetary Nebulae. Here, using a morpho-kinematical code, the true 3D geometry, from which information such as the remnant's inclination angle and expansion velocity can be derived, of the recurrent nova RS Ophiuchi and classical novae V2491 Cygni, V2672 Ophiuchi and KT Eridani are established and related to other characteristics of each system. Each of the classical novae have also been suggested as a recurrent nova candidate. Furthermore, several enhancements to the modelling code were implemented prompted by the work described in this thesis. The RS Oph work entailed detailed modelling of Hubble Space Telescope resolved imaging combined with ground-based spectroscopic observations. Here it was shown that the bipolar morphology of RS Oph consisted of two distinct components with an outer dumbbell and an inner hour glass overdensity, which were required to reproduce both the observed images and spectra. This morphology was suggested to arise due to the interaction between the pre-existing anisotropic red-giant wind and the ejecta. The observed asymmetry in the ACS/HRC image was shown to be due to the finite width and offset from the [OIII] line's rest wavelength

  19. MODIFIED EQUIPARTITION CALCULATION FOR SUPERNOVA REMNANTS

    SciTech Connect

    Arbutina, B.; Urosevic, D.; Andjelic, M. M.; Pavlovic, M. Z.; Vukotic, B.

    2012-02-10

    Determination of the magnetic field strength in the interstellar medium is one of the more complex tasks of contemporary astrophysics. We can only estimate the order of magnitude of the magnetic field strength by using a few very limited methods. Besides the Zeeman effect and Faraday rotation, the equipartition or minimum-energy calculation is a widespread method for estimating magnetic field strength and energy contained in the magnetic field and cosmic-ray particles by using only the radio synchrotron emission. Despite its approximate character, it remains a useful tool, especially when there are no other data about the magnetic field in a source. In this paper, we give a modified calculation that we think is more appropriate for estimating magnetic field strengths and energetics in supernova remnants (SNRs). We present calculated estimates of the magnetic field strengths for all Galactic SNRs for which the necessary observational data are available. The Web application for calculation of the magnetic field strengths of SNRs is available at http://poincare.matf.bg.ac.rs/{approx}arbo/eqp/.

  20. New candidate supernova remnants in nearby galaxies

    NASA Astrophysics Data System (ADS)

    Kopsacheili, Maria; Boumis, Panos; Leonidaki, Ioanna; Zezas, Andreas

    2016-06-01

    Supernova remnants (SNRs) are objects of high importance since they provide major amounts of energy to the interstellar medium (ISM), while at the same time, they depict the end-point state of massive stars (M > 8 Mo). In order to investigate the physical properties of these objects and their interplay with their environment, we have embarked in an extensive investigation of the SNR populations in nearby galaxies of different morphological types. This effort has been initiated with six galaxies, mostly irregulars,in the northern hemisphere (Leonidaki et al. 2010, 2013). Following this context, we present new candidate SNRs (down to fluxes of 10^{-16} erg sec^{-1} cm^-2) of five spiral galaxies in the southern hemisphere (NGC 45, NGC 55, NGC 1313, NGC 1672, NGC 7793), based on deep narrow-band Hα and [S II] images observed with the 4m Blanco telescope at CTIO, Chile. The new detections were achieved by calculating the [S II]/Hα flux ratio, where all sources with [S II]/ Hα > 0.4 were considered as candidate SNRs. Furthermore, we use the derived properties of the newly detected candidate SNRs ([S II]/Hα ratios, Hα fluxes) to investigate how they are distributed according to their brightness and their behavior in different environments (irregulars vs. spirals).

  1. Optical adhesive property study

    SciTech Connect

    Sundvold, P.D.

    1996-01-01

    Tests were performed to characterize the mechanical and thermal properties of selected optical adhesives to identify the most likely candidate which could survive the operating environment of the Direct Optical Initiation (DOI) program. The DOI system consists of a high power laser and an optical module used to split the beam into a number of channels to initiate the system. The DOI requirements are for a high shock environment which current military optical systems do not operate. Five candidate adhesives were selected and evaluated using standardized test methods to determine the adhesives` physical properties. EC2216, manufactured by 3M, was selected as the baseline candidate adhesive based on the test results of the physical properties.

  2. Adhesion of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.

    2007-01-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  3. Adhesives for Aerospace

    NASA Technical Reports Server (NTRS)

    Meade, L. E.

    1985-01-01

    The industry is hereby challenged to integrate adhesive technology with the total structure requirements in light of today's drive into automation/mechanization. The state of the art of adhesive technology is fairly well meeting the needs of the structural designers, the processing engineer, and the inspector, each on an individual basis. The total integration of these needs into the factory of the future is the next collective hurdle to be achieved. Improved processing parameters to fit the needs of automation/mechanization will necessitate some changes in the adhesive forms, formulations, and chemistries. Adhesives have, for the most part, kept up with the needs of the aerospace industry, normally leading the rest of the industry in developments. The wants of the aerospace industry still present a challenge to encompass all elements, achieving a totally integrated joined and sealed structural system. Better toughness with hot-wet strength improvements is desired. Lower cure temperatures, longer out times, and improved corrosion inhibition are desired.

  4. 11. REMNANTS OF FLUME BOX WITHIN CANAL. NOTE THE UPRIGHT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. REMNANTS OF FLUME BOX WITHIN CANAL. NOTE THE UPRIGHT SIDE POSTS BOLTED TO BASE STRINGER AND HORIZONTAL BOARD SIDE WALLS. VIEW IS TO THE SOUTHEAST. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO

  5. 11. Detail view southwest foundation remnants and singlestory flat roof ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Detail view southwest foundation remnants and single-story flat roof building associated with the Clark Cotton Mill/Columbia Narrow Fabrics Co. Factory - Shannock Village, Main Street, North Shannock Road, & West Shannock Road, Richmond (historical), Providence County, RI

  6. Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Shinn, Jong-Ho; Min, Kyoung Wook; Sankrit, Ravi; Ryu, Kwang-Sun; Kim, Il-Joong; Han, Wonyong; Nam, Uk-Won; Park, Jang-Hyun; Edelstein, Jerry; Korpela, Eric J.

    2007-12-01

    We present far-ultraviolet observations of the Antlia supernova remnant obtained with Far-Ultraviolet Imaging Spectrograph (FIMS, also called SPEAR). The strongest lines observed are C IV λλ1548, 1551 and C III λ977. The C IV emission of this mixed-morphology supernova remnant shows a clumpy distribution, and the line intensity is nearly constant with radius. The C III λ977 line, although too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio toward the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium.

  7. Remnants of track girder of east roadbed showing detail of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Remnants of track girder of east roadbed showing detail of granite piers at low tide. View north - New York, New Haven & Hartford Railroad, Fort Point Channel Rolling Lift Bridge, Spanning Fort Point Channel, Boston, Suffolk County, MA

  8. The Supernova Remnant RCW 86 and its environment

    NASA Astrophysics Data System (ADS)

    Duvidovich, L.; Dubner, G.; Giacani, E.; Caragiulo, M.; Condon, B.; Hewitt, J. W.; Giordano, F.; Lemoine-Goumard, M.; Reynoso, E.

    2016-08-01

    RCW 86 (G315.4-2.3) is one of the brightest Galactic supernova remnants in X-rays and has been suggested to be the remnant of the supernova 185 (SN 185). It has a shell-like morphology across almost the entire electromagnetic spectrum (radio, optical, infrared, X-rays and -rays). Detailed hydrodynamic simulations show that the overall dynamics and emission properties in different positions of this remnant can be well reproduced by assuming that it is the remnant of a Type Ia SN that exploded within an elongated cavity. This paper presents preliminary results of the neutral gas study conducted around RCW 86 using 21 cm interferometric observations made with the ATCA (Australia) to explore the gaseous environment of this source.

  9. 3. HISTORIC ROADWAY 2 WITH MILL REMNANTS TO THE RIGHT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. HISTORIC ROADWAY 2 WITH MILL REMNANTS TO THE RIGHT OF TREE. CAMERA POINTED WEST-SOUTHWEST. - Florida Mountain Mining Sites, Historic Roadway No. 2, West flank Florida Mountain, East of Rich Gulch Mine & Mill, Silver City, Owyhee County, ID

  10. 7. INTERIOR OF LIVING ROOM SHOWING REMNANT OF ORIGINAL END ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. INTERIOR OF LIVING ROOM SHOWING REMNANT OF ORIGINAL END WALL AND SMOOTH DRY-WALL FINISH OF 1965 ADDITION IN BACKGROUND. VIEW TO SOUTHWEST. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA

  11. FEATURE C. MACHINE GUN POSITION WITH REMNANT OF MOUNT, VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FEATURE C. MACHINE GUN POSITION WITH REMNANT OF MOUNT, VIEW FACING SOUTH-SOUTHEAST. - Naval Air Station Barbers Point, Battery-Machine Gun Positions, South of Point Cruz Road & west of Coral Sea Road, Ewa, Honolulu County, HI

  12. Western end of ATSF rail yard with remnant of rail ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Western end of ATSF rail yard with remnant of rail spur and dumping location. Concrete vault foundation in foreground. Stone foundation and wood foundation in background. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  13. [A study on the dental adhesive containing phosphate diesters].

    PubMed

    Liu, X; Chen, Z; Guan, L; Li, J; Wu, G; Qui, J

    1990-09-01

    Although a lot of kinds of dental adhesives have been applied recently, all of them cannot meet clinical requirement completely. This paper reports a new dental adhesive containing partial phosphate diesters developed by us. We synthesized aryl phosphorodichloridates (APDC), nine kinds of phosphate diester (PDE) adhesive monomers, sodium p-toluenesulfinate (TSS) and p-toluenesulfinic acid (TSA) accelerators, polymethyl methacrylate (PMMA) powder and the other compounds. The chemical structures of PDE adhesive monomers were confirmed by IR, 1HNMR, 31PNMR, refractive index and elementary analysis etc. The results showed that the tensile bond strength (TBS) between PDE dental adhesive and human tooth was better than others reported in China and some others reported in literature.

  14. Energy of Tycho's Supernova Remnant is increasing with time

    PubMed Central

    Barenblatt, Grigory Isaakovich

    2008-01-01

    It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t1/3. This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified. PMID:18202174

  15. GSH 90-28-17: a possible old supernova remnant

    NASA Astrophysics Data System (ADS)

    Xiao, L.; Zhu, M.

    2014-02-01

    GSH 90-28-17 is a high-latitude Galactic H I supershell, identified in the H I supershell catalogues with a velocity vlsr ˜ -17 km s-1. We used the new Galactic Arecibo L-band Feed Array (GALFA) H I survey data, which have much higher resolution and sensitivity than was previously available, to re-examine the properties of the supershell. We derived a new distance of 400 pc for GSH 90-28-17 and suggested that it is related to the Lac OB1 association. The radius of GSH 90-28-17 is 66.0 ± 3.5 pc. The H I mass of the shell is (3.1 ± 0.1) × 104 M⊙. It has an age of ˜4.5 Myr and a total kinetic energy of (8.2 ± 0.3) × 1048 erg. We extracted radio continuum data for the GSH 90-28-17 region from the 408-MHz All-Sky Survey and Bonn 1420-MHz survey and filtered the diffuse background Galactic emission. A radio loop-like ridge is found to be associated with the H I shell at both frequencies and shows a non-thermal origin, with a temperature-temperature (TT)-plot index of α = -1.35 ± 0.69. In addition, the pulsar J2307+2225, with a similar distance, is found in the shell region. We conclude that GSH 90-28-17 is probably an old, type II supernova remnant in the solar neighbourhood.

  16. Properties of optically selected supernova remnant candidates in M33

    SciTech Connect

    Lee, Jong Hwan; Lee, Myung Gyoon E-mail: mglee@astro.snu.ac.kr

    2014-10-01

    Narrowband images covering strong emission lines are efficient for surveying supernova remnants (SNRs) in nearby galaxies. Using the narrowband images provided by the Local Group Galaxy Survey, we searched for SNRs in M33. Culling the objects with enhanced [S II]/Hα and round morphology in the continuum-subtracted Hα and [S II] images, we produced a list of 199 sources. Among them, 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the sample (170 objects) are likely remnants of core-collapse supernovae (SNe), and 29 are remnants of Type Ia SNe. The cumulative size distribution of these objects is found to be similar to that of the M31 remnants derived in a similar way. We obtain a power-law slope, α = 2.38 ± 0.05. Thus, a majority of the sources are considered to be in the Sedov-Taylor phase, consistent with previous findings. The histogram of the emission-line ratio ([S II]/Hα) of the remnants has two concentrations at [S II]/Hα ∼ 0.55 and ∼0.8, as in M31. Interestingly, L {sub X} (and L {sub 20cm}) of the compact center-bright objects are correlated with their optical luminosity. The remnants with X-ray emission have brighter optical surface brightnesses and smaller diameters than those without X-ray emission.

  17. Properties of Optically Selected Supernova Remnant Candidates in M33

    NASA Astrophysics Data System (ADS)

    Lee, Jong Hwan; Lee, Myung Gyoon

    2014-10-01

    Narrowband images covering strong emission lines are efficient for surveying supernova remnants (SNRs) in nearby galaxies. Using the narrowband images provided by the Local Group Galaxy Survey, we searched for SNRs in M33. Culling the objects with enhanced [S II]/Hα and round morphology in the continuum-subtracted Hα and [S II] images, we produced a list of 199 sources. Among them, 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the sample (170 objects) are likely remnants of core-collapse supernovae (SNe), and 29 are remnants of Type Ia SNe. The cumulative size distribution of these objects is found to be similar to that of the M31 remnants derived in a similar way. We obtain a power-law slope, α = 2.38 ± 0.05. Thus, a majority of the sources are considered to be in the Sedov-Taylor phase, consistent with previous findings. The histogram of the emission-line ratio ([S II]/Hα) of the remnants has two concentrations at [S II]/Hα ~ 0.55 and ~0.8, as in M31. Interestingly, L X (and L 20 cm) of the compact center-bright objects are correlated with their optical luminosity. The remnants with X-ray emission have brighter optical surface brightnesses and smaller diameters than those without X-ray emission.

  18. Black hole remnants and the information loss paradox

    NASA Astrophysics Data System (ADS)

    Chen, P.; Ong, Y. C.; Yeom, D.-h.

    2015-11-01

    Forty years after the discovery of Hawking radiation, its exact nature remains elusive. If Hawking radiation does not carry any information out from the ever shrinking black hole, it seems that unitarity is violated once the black hole completely evaporates. On the other hand, attempts to recover information via quantum entanglement lead to the firewall controversy. Amid the confusions, the possibility that black hole evaporation stops with a "remnant" has remained unpopular and is often dismissed due to some "undesired properties" of such an object. Nevertheless, as in any scientific debate, the pros and cons of any proposal must be carefully scrutinized. We fill in the void of the literature by providing a timely review of various types of black hole remnants, and provide some new thoughts regarding the challenges that black hole remnants face in the context of the information loss paradox and its latest incarnation, namely the firewall controversy. The importance of understanding the role of curvature singularity is also emphasized, after all there remains a possibility that the singularity cannot be cured even by quantum gravity. In this context a black hole remnant conveniently serves as a cosmic censor. We conclude that a remnant remains a possible end state of Hawking evaporation, and if it contains large interior geometry, may help to ameliorate the information loss paradox and the firewall controversy. We hope that this will raise some interests in the community to investigate remnants more critically but also more thoroughly.

  19. A Survey For Broadened CO Lines Toward Galactic Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Charles; Bieging, John H.; Rieke, George

    2016-01-01

    We performed molecular spectroscopy in 12CO J=2-1 with the Heinrich Hertz Submillimeter Telescope toward 50 Galactic supernova remnants as part of a systematic survey for broad molecular line regions indicative of interactions with molecular clouds. These observations revealed broad molecular lines toward nineteen remnants, including nine newly identified associations between molecular clouds and remnants. Morphology of the molecular emission suggests molecular shocks can arise at large separations from the remnants, consistent with a scenario where high-velocity ejecta from bipolar outflows or fast-moving knots shocks nearby molecular clouds. Also, broadened 12CO J=2-1 line emission should be detectable toward virtually all supernova remnant/molecular cloud interactions and, therefore, the total number of observed interactions is low. This result favors predictions that SN feedback plays little or no role in star formation over short timescales. In addition, we find no significant association between TeV gamma-ray sources and molecular cloud interactions, contrary to predictions that supernova remnant/molecular cloud interfaces are the primary venues for cosmic ray acceleration.

  20. Dry adhesives with sensing features

    NASA Astrophysics Data System (ADS)

    Krahn, J.; Menon, C.

    2013-08-01

    Geckos are capable of detecting detachment of their feet. Inspired by this basic observation, a novel functional dry adhesive is proposed, which can be used to measure the instantaneous forces and torques acting on an adhesive pad. Such a novel sensing dry adhesive could potentially be used by climbing robots to quickly realize and respond appropriately to catastrophic detachment conditions. The proposed torque and force sensing dry adhesive was fabricated by mixing Carbon Black (CB) and Polydimethylsiloxane (PDMS) to form a functionalized adhesive with mushroom caps. The addition of CB to PDMS resulted in conductive PDMS which, when under compression, tension or torque, resulted in a change in the resistance across the adhesive patch terminals. The proposed design of the functionalized dry adhesive enables distinguishing an applied torque from a compressive force in a single adhesive pad. A model based on beam theory was used to predict the change in resistance across the terminals as either a torque or compressive force was applied to the adhesive patch. Under a compressive force, the sensing dry adhesive was capable of measuring compression stresses from 0.11 Pa to 20.9 kPa. The torque measured by the adhesive patch ranged from 2.6 to 10 mN m, at which point the dry adhesives became detached. The adhesive strength was 1.75 kPa under an applied preload of 1.65 kPa for an adhesive patch with an adhesive contact area of 7.07 cm2.

  1. Transport of magnetic turbulence in supernova remnants

    NASA Astrophysics Data System (ADS)

    Brose, R.; Telezhinsky, I.; Dwarkadas, V.; Pohl, M.

    2016-06-01

    Supernova remnants are known as sources of galactic cosmic rays for their non-thermal emission of radio waves, X-rays, and gamma-rays. However, the observed CR spectra are hard to reproduce within the standard acceleration theories based on the assumption of Bohm diffusion and steady-state calculations. We point out that a time-dependent treatment of the acceleration process together with a self-consistent treatment of the scattering turbulence is necessary. Therefore we numerically solve the coupled system of transport equations for cosmic rays and isotropic Alfvénic turbulence. The equations are coupled through the growth rate of the turbulence determined by the cosmicray gradient and the spatial diffusion coefficient of cosmic rays given by the spectral energy density of the turbulence. The system is solved on a co-moving expanding grid extending upstream for dozens of shock radii, allowing for self-consistent study of cosmic-ray diffusion in the vicinity of their acceleration site. The transport equation for cosmic rays is solved in a test-particle approach based on pre-calculated hydro models. We demonstrate that the system is typically not in a steady state. In fact, even after several thousand years of evolution, no equilibrium situation is reached. The resulting time-dependent particle spectra strongly differ from those derived assuming a steady state and Bohm diffusion. The turbulence spectra show that bohmlike diffusion is achieved only in a small energy band. Our results indicate that proper account for the evolution of scattering turbulence is crucial for the formation of the observed soft spectra.

  2. Transport of magnetic turbulence in supernova remnants

    NASA Astrophysics Data System (ADS)

    Brose, R.; Telezhinsky, I.; Pohl, M.

    2016-08-01

    Context. Supernova remnants are known as sources of Galactic cosmic rays for their nonthermal emission of radio waves, X-rays, and gamma rays. However, the observed soft broken power-law spectra are hard to reproduce within standard acceleration theory based on the assumption of Bohm diffusion and steady-state calculations. Aims: We point out that a time-dependent treatment of the acceleration process together with a self-consistent treatment of the scattering turbulence amplification is necessary. Methods: We numerically solve the coupled system of transport equations for cosmic rays and isotropic Alfvénic turbulence. The equations are coupled through the growth rate of turbulence determined by the cosmic-ray gradient and the spatial diffusion coefficient of cosmic rays determined by the energy density of the turbulence. The system is solved on a comoving expanding grid extending upstream for dozens of shock radii, allowing for the self-consistent study of cosmic-ray diffusion in the vicinity of their acceleration site. The transport equation for cosmic rays is solved in a test-particle approach. Results: We demonstrate that the system is typically not in a steady state. In fact, even after several thousand years of evolution, no equilibrium situation is reached. The resulting time-dependent particle spectra strongly differ from those derived assuming a steady state and Bohm diffusion. Our results indicate that proper accounting for the evolution of the scattering turbulence and hence the particle diffusion coefficient is crucial for the formation of the observed soft spectra. In any case, the need to continuously develop magnetic turbulence upstream of the shock introduces nonlinearity in addition to that imposed by cosmic-ray feedback.

  3. Supernova Remnants, Cosmic Rays, and GLAST

    SciTech Connect

    Reynolds, Steve

    2006-02-13

    The shock waves of supernova remnants (SNRs) are the traditional sources of Galactic cosmic rays, at least up to about 3000 TeV (the "knee" energy in the cosmic-ray spectrum). In the last decade or so, X-ray observations have confirmed in a few SNRs the presence of synchrotron-X-ray-emitting electrons with energies of order 100 TeV. TeV photons from SNRs have been observed with ground-based air Cerenkov telescopes as well, but it is still unclear whether they are due to hadronic processes (inelastic p-p scattering of cosmic-ray protons from thermal gas, with secondary neutral pions decaying to gamma rays), or to leptonic processes (inverse-Compton upscattering of cosmic microwave background photons, or bremsstrahlung). The spatial structure of synchrotron X-rays as observed with the Chandra X-ray Observatory suggests the remarkable possibility that magnetic fields are amplified by orders of magnitude in strong shock waves. The electron spectra inferred from X-rays reach 100 TeV, but at that energy are cutting off steeply, well below the "knee" energy. Are the cutoff processes due only to radiative losses so that ion spectra might continue unsteepened? Can we confirm the presence of energetic ions in SNRs at all? Are typical SNRs capable of supplying the pool of Galactic cosmic rays? Is strong magnetic-field amplification a property of strong astrophysical shocks in general? These major questions require the next generation of observational tools. I shall outline the theoretical and observational framework of particle acceleration to high energies in SNRs, and shall describe how GLAST will advance this field.

  4. Supernova Remnants, Cosmic Rays, and GLAST

    SciTech Connect

    Reynolds, Steve

    2006-02-13

    The shock waves of supernova remnants (SNRs) are the traditional sources of Galactic cosmic rays, at least up to about 3000 TeV (the 'knee' energy in the cosmic-ray spectrum). In the last decade or so, X-ray observations have confirmed in a few SNRs the presence of synchrotron-X-ray-emitting electrons with energies of order 100 TeV. TeV photons from SNRs have been observed with ground-based air Cerenkov telescopes as well, but it is still unclear whether they are due to hadronic processes (inelastic p-p scattering of cosmic-ray protons from thermal gas, with secondary neutral pions decaying to gamma rays), or to leptonic processes (inverse-Compton upscattering of cosmic microwave background photons, or bremsstrahlung). The spatial structure of synchrotron X-rays as observed with the Chandra X-ray Observatory suggests the remarkable possibility that magnetic fields are amplified by orders of magnitude in strong shock waves. The electron spectra inferred from X-rays reach 100 TeV, but at that energy are cutting off steeply, well below the 'knee' energy. Are the cutoff processes due only to radiative losses so that ion spectra might continue unsteepened? Can we confirm the presence of energetic ions in SNRs at all? Are typical SNRs capable of supplying the pool of Galactic cosmic rays? Is strong magnetic-field amplification a property of strong astrophysical shocks in general? These major questions require the next generation of observational tools. I shall outline the theoretical and observational framework of particle acceleration to high energies in SNRs, and shall describe how GLAST will advance this field.

  5. Supernova Remnant Observations with Micro-X

    NASA Astrophysics Data System (ADS)

    Figueroa, Enectali

    Micro-X is a sounding rocket payload that combines an X-ray microcalorimeter with an imaging mirror to offer breakthrough science from high spectral resolution observations of extended X-ray sources. This payload has been in design and development for the last five years and is now completely built and undergoing integration; its first flight will be in November, 2012, as part of our current NASA award. This four-year follow-on proposal seeks funding for: (1) analysis of the first flight data, (2) the second flight and its data analysis, (3) development of payload upgrades and launch of the third flight, and (4) third flight data analysis. The scientific payload consists of a Transition Edge Sensor (TES) microcalorimeter array at the focus of a flight-proven conical imaging mirror. Micro-X capitalizes on three decades of NASA investment in the development of microcalorimeters and X-ray imaging optics. Micro-X offers a unique combination of bandpass, collecting area, and spectral and angular resolution. The spectral resolution goal across the 0.2 - 3.0 keV band is 2 - 4 eV Full-Width at Half Maximum (FWHM). The measured angular resolution of the mirror is 2.4 arcminute Half-Power Diameter (HPD). The effective area of the mirror, 300 square centimeters at 1 keV, is sufficient to provide observations of unprecedented quality of several astrophysical X-ray sources, even in a brief sounding rocket exposure of 300 sec. Our scientific program for this proposal will focus on supernova remnants (SNRs), whose spatial extent has made high-energy resolution observations with grating instruments extremely challenging. X-ray observations of SNRs with microcalorimeters will enable the study of the detailed atomic physics of the plasma; the determination of temperature, turbulence, and elemental abundances; and in conjunction with historical data, full three dimensional mapping of the kinematics of the remnant. These capabilities will open new avenues towards understanding the

  6. Detecting Enriched Ejacta in the Remnant of SN 185 AD

    NASA Astrophysics Data System (ADS)

    Fesen, Robert A.

    Low dispersion IUE spectra of early-type stars lying behind young galactic supernova remnants can provide extremely valuable and unique information via line-of-sight interception of a remnant's ejecta producing strong absorptions lines. From such data, one can directly probe the elemental composition of the remnant's cool ejecta and, in turn, obtain some clue as to the type of supernova involved and explosive nucleosynthesis. Although realized for sometime as a potentially powerful technique due to the great sensitivity of heavy element resonance UV lines for detecting even very low column densities, in practice this method has been attempted only once due to problems in identifying early-type background target stars as well as reddening limitations. The one previous study using this technique has yielded exciting and very important new data on the remnant of SN 1006 AD. Analysis of IUE data for a faint sdOB star situated behind this young supernova remnant show the presence of very strong and definitely non-stellar absorption lines in this star's UV spectrum due to several individual knots of ejecta along the line-of-sight. These features are identified as redshifted S II (1259, 1254), O I (1302), and Si IV (1393, 1402) respectively at radial velocities of 5000 to 6700 krn s^-1 (Fesen, Wu, Leventhal, and Hamilton 1986). Also, very broad and strong absorption Fe II lines at 2370 and 2600 A indicate an Fe II mass of about 0.1 solar mass. This IUE detection is presently the only direct observation of the expected large mass of iron in SN 1006. Obviously, one would very much like to apply this now proven method to investigate other young galactic supernova remnants. Recent SNR studies indicate there is one (but presently only one) young SNR for which similar observations are possible, namely SN 185 (= RCW 86). Estimates for the remnant's distance have recently decreased from 2.5 kpc to < 1.5 kpc and this together with new, more accurate radio maps make UV observations

  7. Magnetic field switchable dry adhesives.

    PubMed

    Krahn, Jeffrey; Bovero, Enrico; Menon, Carlo

    2015-02-01

    A magnetic field controllable dry adhesive device is manufactured. The normal adhesion force can be increased or decreased depending on the presence of an applied magnetic field. If the magnetic field is present during the entire normal adhesion test cycle which includes both applying a preloading force and measuring the pulloff pressure, a decrease in adhesion is observed when compared to when there is no applied magnetic field. Similarly, if the magnetic field is present only during the preload portion of the normal adhesion test cycle, a decrease in adhesion is observed because of an increased stiffness of the magnetically controlled dry adhesive device. When the applied magnetic field is present during only the pulloff portion of the normal adhesion test cycle, either an increase or a decrease in normal adhesion is observed depending on the direction of the applied magnetic field.

  8. Magnetic Fields in Supernova Remnants and Pulsar-Wind Nebulae

    NASA Astrophysics Data System (ADS)

    Reynolds, Stephen P.; Gaensler, B. M.; Bocchino, Fabrizio

    2012-05-01

    We review the observations of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe) that give information on the strength and orientation of magnetic fields. Radio polarimetry gives the degree of order of magnetic fields, and the orientation of the ordered component. Many young shell supernova remnants show evidence for synchrotron X-ray emission. The spatial analysis of this emission suggests that magnetic fields are amplified by one to two orders of magnitude in strong shocks. Detection of several remnants in TeV gamma rays implies a lower limit on the magnetic-field strength (or a measurement, if the emission process is inverse-Compton upscattering of cosmic microwave background photons). Upper limits to GeV emission similarly provide lower limits on magnetic-field strengths. In the historical shell remnants, lower limits on B range from 25 to 1000 μG. Two remnants show variability of synchrotron X-ray emission with a timescale of years. If this timescale is the electron-acceleration or radiative loss timescale, magnetic fields of order 1 mG are also implied. In pulsar-wind nebulae, equipartition arguments and dynamical modeling can be used to infer magnetic-field strengths anywhere from ˜5 μG to 1 mG. Polarized fractions are considerably higher than in SNRs, ranging to 50 or 60% in some cases; magnetic-field geometries often suggest a toroidal structure around the pulsar, but this is not universal. Viewing-angle effects undoubtedly play a role. MHD models of radio emission in shell SNRs show that different orientations of upstream magnetic field, and different assumptions about electron acceleration, predict different radio morphology. In the remnant of SN 1006, such comparisons imply a magnetic-field orientation connecting the bright limbs, with a substantial density gradient across the remnant.

  9. Regulation of Cell Adhesion Strength by Peripheral Focal Adhesion Distribution

    PubMed Central

    Elineni, Kranthi Kumar; Gallant, Nathan D.

    2011-01-01

    Cell adhesion to extracellular matrices is a tightly regulated process that involves the complex interplay between biochemical and mechanical events at the cell-adhesive interface. Previous work established the spatiotemporal contributions of adhesive components to adhesion strength and identified a nonlinear dependence on cell spreading. This study was designed to investigate the regulation of cell-adhesion strength by the size and position of focal adhesions (FA). The cell-adhesive interface was engineered to direct FA assembly to the periphery of the cell-spreading area to delineate the cell-adhesive area from the cell-spreading area. It was observed that redistributing the same adhesive area over a larger cell-spreading area significantly enhanced cell-adhesion strength, but only up to a threshold area. Moreover, the size of the peripheral FAs, which was interpreted as an adhesive patch, did not directly govern the adhesion strength. Interestingly, this is in contrast to the previously reported functional role of FAs in regulating cellular traction where sizes of the peripheral FAs play a critical role. These findings demonstrate, to our knowledge for the first time, that two spatial regimes in cell-spreading area exist that uniquely govern the structure-function role of FAs in regulating cell-adhesion strength. PMID:22208188

  10. Adhesive particle shielding

    DOEpatents

    Klebanoff, Leonard Elliott; Rader, Daniel John; Walton, Christopher; Folta, James

    2009-01-06

    An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.

  11. Natural Underwater Adhesives

    PubMed Central

    Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

    2011-01-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  12. SUPERNOVA REMNANT PROGENITOR MASSES IN M31

    SciTech Connect

    Jennings, Zachary G.; Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Fouesneau, Morgan; Weisz, Daniel R.; Murphy, Jeremiah W.; Dolphin, Andrew E. E-mail: adolphin@raytheon.com

    2012-12-10

    Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (M{sub ZAMS}) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star, then assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the M{sub ZAMS} from this age. Because our technique is not contingent on identification or precise location of the progenitor star, it can be applied to the location of any known SNRs. We identify significant young star formation around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of {approx}2 increase over currently measured progenitor masses. We consider the remaining six SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped their birth sites. In general, the distribution of recovered progenitor masses is bottom-heavy, showing a paucity of the most massive stars. If we assume a single power-law distribution, dN/dM{proportional_to}M{sup {alpha}}, then we find a distribution that is steeper than a Salpeter initial mass function (IMF) ({alpha} = -2.35). In particular, we find values of {alpha} outside the range -2.7 {>=} {alpha} {>=} -4.4 to be inconsistent with our measured distribution at 95% confidence. If instead we assume a distribution that follows a Salpeter IMF up to some maximum mass, then we find that values of M{sub Max} > 26 are inconsistent with the measured distribution at 95% confidence. In either scenario, the data suggest that some fraction of massive stars may not explode. The result is preliminary and requires more SNRs and further analysis. In addition, we use our distribution to estimate a

  13. New Galactic supernova remnants discovered with IPHAS

    NASA Astrophysics Data System (ADS)

    Sabin, L.; Parker, Q. A.; Contreras, M. E.; Olguín, L.; Frew, D. J.; Stupar, M.; Vázquez, R.; Wright, N. J.; Corradi, R. L. M.; Morris, R. A. H.

    2013-05-01

    As part of a systematic search programme of a 10° wide strip of the northern Galactic plane, we present preliminary evidence for the discovery of four (and possibly five) new supernova remnants (SNRs). The pilot search area covered the 19-20 h right ascension zone sampling from +20° to +55° in declination using binned mosaic images from the Isaac Newton Telescope Photometric Hα Survey (IPHAS). The optical identification of the candidate SNRs was based mainly on their filamentary and arc-like emission morphologies, their apparently coherent, even if fractured, structure and clear disconnection from any diffuse neighbouring H II region type nebulosity. Follow-up optical spectroscopy was undertaken, sampling carefully across prominent features of these faint sources. The resulting spectra revealed typical emission-line ratios for shock-excited nebulae which are characteristic of SNRs, which, along with the latest diagnostic diagrams, strongly support the likely SNR nature of these sources: G038.7-1.3 (IPHASX J190640.5+042819), G067.6+0.9 (IPHASX J195744.9+305306), G066.0-0.0 (IPHASX J195749.2+290259) and G065.8-0.5 (IPHASX J195920.4+283740). A fifth possible younger, higher density nebula SNR candidate, G067.8+0.5 (IPHASX J200002.4+305035), was discovered ˜5 arcmin to the west of IPHASX J195744.9+305306, and it warrants further study. A multiwavelength cross-check from available archived data in the regions of these candidates was also performed with a focus on possible radio counterparts. A close positional match between previously unrecognized radio structures at several frequencies and across various components of the Hα optical image data was found for all SNR candidates. This lends further direct support for the SNR nature of these objects. Evolved SNRs may have very weak and/or highly fragmented radio emission which could explain why they had not been previously recognized, but the association becomes clear in combination with the optical emission.

  14. Nonequilibria in thermal emission from supernova remnants

    NASA Astrophysics Data System (ADS)

    Masai, Kuniaki

    1994-12-01

    Nonequipartition between the electron and the ion temperatures, and nonequilibrium ionization are discussed in view of thermal X-ray emission from young supernova remnants (SNRs). For electron heating we consider Coulomb collisions with ions in the postshock region and derive an analytical solution for the electron temperature under the adiabatic condition. By Taylor expansion of the solution, we obtain the electron temperature as a function of the electron density, time, and the shock velocity or the shock temperature (Ts. Defining the equipartition time (Spitzer 1962), tEeq, it is shown that the electron temperature, Te, increases to be approximately equals 0.1 Ts and 0.3 Ts in 10-3 tEeq and 10-2 tEeq, respectively. The result is applied to the self-similar solutions for SNRs in the adiabatic phase, i.e., the free expansion phase and the Sedov phase. We predict a slower variation of the electron temperature than the shock temperature in SNRs expanding into a uniform density medium, while a faster decrease of the electron temperature than the shock temperature in explosions out of the circumstellar matter. We demonstrate the existence of an electron temperature plateau in the shocked matter of an SNR and give analytical expression for the electron temperature and the resultant free-free luminosity. In the free expansion phase, the electron temperatures of the reverse- and the blast-shocked matter are closer to each other than in the case of full equipartition within the shock. This results in a larger difference in the free-free luminosities of the two shocks than the case of full equipartition. Ionization processes are discussed in the framework of the eigenvalue problem to find the key matrix element, which is a pivot of the transformation, and gives the characteristic time constant. The ionization time approximately equals 1012ne-1 s, where ne is the electron density, and has no systematic dependence either on the electron temperature or the atomic number. The

  15. Elastomer toughened polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L. (Inventor)

    1983-01-01

    A rubber-toughened addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state, and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride was mixed, and utilizing solvent or mixture of solvents for the reaction.

  16. Adhesion in hydrogel contacts

    NASA Astrophysics Data System (ADS)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  17. Effect of orthodontic debonding and residual adhesive removal on 3D enamel microroughness

    PubMed Central

    Tomkowski, Robert; Tandecka, Katarzyna; Stepien, Piotr; Szatkiewicz, Tomasz; Sporniak-Tutak, Katarzyna; Grocholewicz, Katarzyna

    2016-01-01

    scale-limited surface). Discussion Confocal laser microscopy allowed 3D surface analysis of enamel surface, avoiding the limitations of contact profilometry. Tungsten carbide burs are the most popular adhesive removing tools, however, the results of the present study indicate, that a one step polisher and finisher as well as Adhesive Residue Remover are less detrimental to the enamel. This is in agreement with a recent study based on direct 3D scanning enamel surface. It proved, that a one-step finisher and polisher as well as Adhesive Residue Remover are characterized by a similar effectiveness in removing residual remnants as tungsten carbide bur, but they remove significantly less enamel. Conclusion Orthodontic debonding and removal of adhesive remnants increases enamel roughness. The smoothest surfaces were achieved using Adhesive Residue Remover, and the roughest using tungsten carbide bur. PMID:27761343

  18. The influence of gas on the structure of merger remnants

    NASA Astrophysics Data System (ADS)

    Naab, Thorsten; Jesseit, Roland; Burkert, Andreas

    2006-10-01

    We present a large set of merger simulations of early-type disc galaxies with mass ratios of 1:1 and 3:1 and 10 per cent of the total disc mass in gas. The internal orbital structure and the kinematic and photometric properties of the remnants are analysed in detail and compared to pure stellar mergers. In contrast to the collisionless case, equal-mass mergers with gas do not result in very boxy remnants which is caused by the suppression of box orbits and the change of the projected shape of minor-axis tube orbits in the more axisymmetric remnants. The isophotal shape of 3:1 remnants and the global kinematic properties of 1:1 and 3:1 remnants are only weakly affected by the presence of gas. 1:1 remnants are slowly rotating, whereas 3:1 remnants are fast rotating and discy. The shape of the stellar line-of-sight velocity distributions (LOSVDs) is strongly influenced by gas. Within the effective radius, the LOSVDs of collisionless remnants have broad leading wings while their gaseous counterparts show steep leading wings, more consistent with observations of elliptical galaxies. We show that this change is also caused by the suppressed populating of box orbits and it is amplified by the formation of extended gas discs in the merger remnants which might eventually turn into stars. If elliptical galaxies have formed from mergers, our results indicate that massive, slowly rotating boxy elliptical galaxies cannot have formed from dissipative mergers of discs. Pure stellar (dry) mergers are the more likely candidates. On the other hand, lower mass, fast rotating and discy ellipticals can have formed from dissipative (wet) mergers of early-type discs. So far, only unequal-mass disc mergers with gas can successfully explain their observed substructure. This is consistent with the revised morphological classification scheme of increasing importance of gas dissipation when moving from boxy to discy ellipticals and then to spiral galaxies, proposed by Kormendy & Bender.

  19. Switchable bio-inspired adhesives

    NASA Astrophysics Data System (ADS)

    Kroner, Elmar

    2015-03-01

    Geckos have astonishing climbing abilities. They can adhere to almost any surface and can run on walls and even stick to ceilings. The extraordinary adhesion performance is caused by a combination of a complex surface pattern on their toes and the biomechanics of its movement. These biological dry adhesives have been intensely investigated during recent years because of the unique combination of adhesive properties. They provide high adhesion, allow for easy detachment, can be removed residue-free, and have self-cleaning properties. Many aspects have been successfully mimicked, leading to artificial, bio-inspired, patterned dry adhesives, and were addressed and in some aspects they even outperform the adhesion capabilities of geckos. However, designing artificial patterned adhesion systems with switchable adhesion remains a big challenge; the gecko's adhesion system is based on a complex hierarchical surface structure and on advanced biomechanics, which are both difficult to mimic. In this paper, two approaches are presented to achieve switchable adhesion. The first approach is based on a patterned polydimethylsiloxane (PDMS) polymer, where adhesion can be switched on and off by applying a low and a high compressive preload. The switch in adhesion is caused by a reversible mechanical instability of the adhesive silicone structures. The second approach is based on a composite material consisting of a Nickel- Titanium (NiTi) shape memory alloy and a patterned adhesive PDMS layer. The NiTi alloy is trained to change its surface topography as a function of temperature, which results in a change of the contact area and of alignment of the adhesive pattern towards a substrate, leading to switchable adhesion. These examples show that the unique properties of bio-inspired adhesives can be greatly improved by new concepts such as mechanical instability or by the use of active materials which react to external stimuli.

  20. Featured Image: A Supernova Remnant in X-Rays

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-09-01

    This is a three-color X-ray image taken by Chandra of the supernova remnant RCW 103. This supernova remnant is an unusual system: its young, but unlike other remnants of its age, metal-rich ejecta hadnt previously been discovered in it. In this paper, Kari Frank (Pennsylvania State University) and collaborators analyze the three deepest Chandra observations of RCW 103 and find the first evidence for metal-rich ejecta emission scattered throughout the remnant. Their analyses also help to constrain the identity of the mysterious compact stellar object powering the remnant. In this image, red = 0.30.85 keV, green = 0.851.70 keV, and blue = 1.73.0 keV; click on the image for the full view. For more information and the original image, see the paper here:Kari A. Frank et al 2015 ApJ 810 113 doi:10.1088/0004-637X/810/2/113.

  1. Fermi-LAT observations of supernova remnants Kesteven 79

    SciTech Connect

    Auchettl, Katie; Slane, Patrick; Castro, Daniel

    2014-03-01

    In this paper, we report on the detection of γ-ray emission coincident with the Galactic supernova remnant (SNR) Kesteven 79 (Kes 79). We analyzed approximately 52 months of data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Kes 79 is thought to be interacting with adjacent molecular clouds, based on the presence of strong {sup 12}CO J = 1 → 0 and HCO{sup +} J = 1 → 0 emission and the detection of 1720 MHz line emission toward the east of the remnant. Acceleration of cosmic rays is expected to occur at SNR shocks, and SNRs interacting with dense molecular clouds provide a good testing ground for detecting and analyzing the production of γ-rays from the decay of π{sup 0} into two γ-ray photons. This analysis investigates γ-ray emission coincident with Kes 79, which has a detection significance of ∼7σ. Additionally, we present an investigation of the spatial and spectral characteristics of Kes 79 using multiple archival XMM-Newton observations of this remnant. We determine the global X-ray properties of Kes 79 and estimate the ambient density across the remnant. We also performed a similar analysis for Galactic SNR Kesteven 78 (Kes 78), but due to large uncertainties in the γ-ray background model, no conclusion can be made about an excess of GeV γ-ray associated with the remnant.

  2. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects.

  3. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives

    PubMed Central

    2015-01-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm2 provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  4. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  5. Wood Composite Adhesives

    NASA Astrophysics Data System (ADS)

    Gomez-Bueso, Jose; Haupt, Robert

    The global environment, in which phenolic resins are being used for wood composite manufacture, has changed significantly during the last decade. This chapter reviews trends that are driving the use and consumption of phenolic resins around the world. The review begins with recent data on volume usage and regional trends, followed by an analysis of factors affecting global markets. In a section on environmental factors, the impact of recent formaldehyde emission regulations is discussed. The section on economics introduces wood composite production as it relates to the available adhesive systems, with special emphasis on the technical requirement to improve phenolic reactivity. Advances in composite process technology are introduced, especially in regard to the increased demands the improvements place upon adhesive system performance. The specific requirements for the various wood composite families are considered in the context of adhesive performance needs. The results of research into current chemistries are discussed, with a review of recent findings regarding the mechanisms of phenolic condensation and acceleration. Also, the work regarding alternate natural materials, such as carbohydrates, lignins, tannins, and proteinaceous materials, is presented. Finally, new developments in alternative adhesive technologies are reported.

  6. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  7. Resistance heating releases structural adhesive

    NASA Technical Reports Server (NTRS)

    Glemser, N. N.

    1967-01-01

    Composite adhesive package bonds components together for testing and enables separation when testing is completed. The composite of adhesives, insulation and a heating element separate easily when an electrical current is applied.

  8. 3-D foam adhesive deposition

    NASA Technical Reports Server (NTRS)

    Lemons, C. R.; Salmassy, O. K.

    1976-01-01

    Bonding method, which reduces amount and weight of adhesive, is applicable to foam-filled honeycomb constructions. Novel features of process include temperature-viscosity control and removal of excess adhesive by transfer to cellophane film.

  9. Assessment of adhesion formation after laparoscopic intraperitoneal implantation of Dynamesh IPOM mesh

    PubMed Central

    Jałyński, Marek; Piskorz, Łukasz; Brocki, Marian

    2013-01-01

    Introduction Formation of adhesions after laparoscopic hernia repair using the intra-peritoneal onlay mesh (IPOM) procedure can lead to intestinal obstruction or mesh erosion into intestinal lumen. The aims of this study included: measurement of adhesion formation with Dynamesh IPOM after laparoscopic intraperitoneal implantation, and assessment of the occurrence of isolated adhesions at the fastening sites of slowly absorbable sutures. Material and methods Twelve healthy pigs underwent laparoscopic implantation of 2 Dynamesh IPOM mesh fragments each, one was fastened with PDSII, and the other with Maxon sutures. An assessment of adhesion formation was carried out after 6 weeks and included an evaluation of surface area, hardness according to the Zhulke scale, and index values. The occurrence of isolated adhesions at slowly absorbable suture fixation points was also analyzed. Results Adhesions were noted in 83.3% of Dynamesh IPOM meshes. Adhesions covered on average 37.7% of the mesh surface with mean hardness 1.46 and index value 78.8. In groups fixed with PDS in comparison to Maxon sutures adhesions covered mean 31.6% vs. 42.5% (p = 0.62) of the mesh surface, mean hardness was 1.67 vs.1.25 (p = 0.34) and index 85.42 vs. 72.02 (p = 0.95). Conclusions The Dynamesh IPOM mesh, in spite of its anti-adhesive layer of PVDF, does not prevent the formation of adhesions. Adhesion hardness, surface area, and index values of the Dynamesh IPOM mesh are close to the mean values of these parameters for other commercially available 2-layer meshes. Slowly absorbable sutures used for fastening did not increase the risk of adhesion formation. PMID:23847671

  10. Supernovae Explosions Theory and Compact Remnant of SN 1987A

    NASA Astrophysics Data System (ADS)

    Chechetkin, V. M.; Baranov, A. A.; Popov, M. V.; Lugovsky, A. Yu.

    Hydrodynamics of massive star explosion within a non-spherical supernova model is presented. The explosive burning is computed in the He-core of a progenitor. It is assumed that the iron core and the other layers of the intermediate-mass nuclei formed a compact central object beyond the mass cut and its formation did not disturb the stellar envelope. A Piecewise Parabolic Method on a Local stencil (PPML) is applied to simulate the hydrodynamics of the explosion. The problem of compact remnant creation after the explosion is discussed in relation with SN 1987A observations. The computations show that at the neighbourhood of compact remnant a significant quantity of the matter should remain. The accretion of this matter to the compact remnant should produce strong radiation which is not observed in the case of SN 1987A.

  11. Multiwavelength Signatures of Cosmic Ray Acceleration by Young Supernova Remnants

    SciTech Connect

    Vink, Jacco

    2008-12-24

    An overview is given of multiwavelength observations of young supernova remnants, with a focus on the observational signatures of efficient cosmic ray acceleration. Some of the effects that may be attributed to efficient cosmic ray acceleration are the radial magnetic fields in young supernova remnants, magnetic field amplification as determined with X-ray imaging spectroscopy, evidence for large post-shock compression factors, and low plasma temperatures, as measured with high resolution optical/UV/X-ray spectroscopy. Special emphasis is given to spectroscopy of post-shock plasma's, which offers an opportunity to directly measure the post-shock temperature. In the presence of efficient cosmic ray acceleration the post-shock temperatures are expected to be lower than according to standard equations for a strong shock. For a number of supernova remnants this seems indeed to be the case.

  12. A HIRES analysis of the FIR emission of supernova remnants

    NASA Technical Reports Server (NTRS)

    Wang, Zhong

    1994-01-01

    The high resolution (HiRes) algorithm has been used to analyze the far infrared emission of shocked gas and dust in supernova remnants. In the case of supernova remnant IC 443, we find a very good match between the resolved features in the deconvolved images and the emissions of shocked gas mapped in other wavelengths (lines of H2, CO, HCO+, and HI). Dust emission is also found to be surrounding hot bubbles of supernova remnants which are seen in soft X-ray maps. Optical spectroscopy on the emission of the shocked gas suggests a close correlation between the FIR color and local shock speed, which is a strong function of the ambient (preshock) gas density. These provide a potentially effective way to identify regions of strong shock interaction, and thus facilitate studies of kinematics and energetics in the interstellar medium.

  13. A multiwavelength investigation of the supernova remnant IC 443

    NASA Technical Reports Server (NTRS)

    Mufson, S. L.; Mccollough, M. L.; Dickel, J. R.; Petre, R.; White, R.

    1986-01-01

    Multiwavelength observations of the supernova remnant IC 443 at radio, infrared, optical, ultraviolet, and X-ray wavelengths are presented. This morphological study of IC 443 presents a detailed picture of an adolescent supernova remnant in a multiphase interstellar medium. Radio observations show that better than 80 percent of the continuum emission at 18 cm is in a large-scale (greater than 18 arcmin) component. Decomposition of the infrared data shows that radiatively heated dust, shocked blackbody dust emission, and infrared line emission are all important components of the observed IRAS fluxes. The morphology of the IC 443 region is consistent with a supernova blast in an interstellar medium with a nonuniform distribution of clouds. The bright northeast rim and the great extent of the remnant to the southwest are most easily explained by a cloud filling factor which is greatest in the northeast and falls off toward the southwest.

  14. Black hole remnants due to Planck-length deformed QFT

    NASA Astrophysics Data System (ADS)

    Dirkes, Alain R. P.; Maziashvili, Michael; Silagadze, Zurab K.

    2016-10-01

    It was argued in a number of papers that the gravitational potential calculated by using the modified QFT that follows from the Planck-length deformed uncertainty relation implies the existence of black hole (BH) remnants of the order of the Planck mass. Usually, this sort of QFTs are endowed with two specific features, the modified dispersion relation, which is universal, and the concept of minimum length, which, however, is not universal. While the emergence of the minimum length most readily leads to the idea of the BH remnants, here, we examine the behavior of the potential that follows from the Planck-length deformed QFT in the absence of the minimum length and show that it might also lead to the formation of the Planck mass BHs in some particular cases. The calculations are made for higher-dimensional case as well. Such BH remnants might be considered as a possible candidates for the dark-matter.

  15. Coating Reduces Ice Adhesion

    NASA Technical Reports Server (NTRS)

    Smith, Trent; Prince, Michael; DwWeese, Charles; Curtis, Leslie

    2008-01-01

    The Shuttle Ice Liberation Coating (SILC) has been developed to reduce the adhesion of ice to surfaces on the space shuttle. SILC, when coated on a surface (foam, metal, epoxy primer, polymer surfaces), will reduce the adhesion of ice by as much as 90 percent as compared to the corresponding uncoated surface. This innovation is a durable coating that can withstand several cycles of ice growth and removal without loss of anti-adhesion properties. SILC is made of a binder composed of varying weight percents of siloxane(s), ethyl alcohol, ethyl sulfate, isopropyl alcohol, and of fine-particle polytetrafluoroethylene (PTFE). The combination of these components produces a coating with significantly improved weathering characteristics over the siloxane system alone. In some cases, the coating will delay ice formation and can reduce the amount of ice formed. SILC is not an ice prevention coating, but the very high water contact angle (greater than 140 ) causes water to readily run off the surface. This coating was designed for use at temperatures near -170 F (-112 C). Ice adhesion tests performed at temperatures from -170 to 20 F (-112 to -7 C) show that SILC is a very effective ice release coating. SILC can be left as applied (opaque) or buffed off until the surface appears clear. Energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) data show that the coating is still present after buffing to transparency. This means SILC can be used to prevent ice adhesion even when coating windows or other objects, or items that require transmission of optical light. Car windshields are kept cleaner and SILC effectively mitigates rain and snow under driving conditions.

  16. Cosmic rays and the Monogem supernova remnant

    NASA Astrophysics Data System (ADS)

    Erlykin, A. D.; Wolfendale, A. W.

    2004-10-01

    Recent findings indicate that the Monogem Ring and the associated pulsar PSR B0656 + 14 may be the `Single Source' responsible for the formation of the sharp knee in the cosmic ray energy spectrum at ˜3 PeV. The energy spectrum of cosmic rays expected for the Monogem Ring supernova remnant (SNR) from our SNR acceleration model [J. Phys. G: Nucl. Part. Phys. 27 (2001) 941] has been published by us elsewhere [J. Phys. G: Nucl. Part. Phys. 29 (2003) 709] . In this paper we go on to estimate the contribution of the pulsar B0656 + 14 to the cosmic rays in the PeV region. We conclude that although the pulsar can contribute to the formation of the knee, it cannot be the dominant source of it and an SNR is still needed. We also examine the possibility of the pulsar giving the peak of the extensive air shower (EAS) intensity observed from the region inside the Monogem Ring [ApJ Lett. 597 (2003) L129]. The estimates of the gamma-ray flux produced by cosmic ray particles from this pulsar indicate that it can be the source of the observed peak, if the particles were confined within the SNR during a considerable fraction of its total age. The flux of gamma quanta at PeV energies has a high sensitivity to the duration of the confinement. The estimates of this time and of the following diffusion of cosmic rays from the confinement volume turn out to be in remarkable agreement with the time needed for these cosmic rays to propagate to the solar system and to form the observed knee in the cosmic ray energy spectrum. Other possible mechanisms for the production of particles which could give rise to the observed narrow peak in the EAS intensity were also examined. Electrons scattered on the microwave background or on X-rays, emitted by SNR, cannot be responsible for the gamma-quanta in the peak. Neutrons produced in PP-collisions or released from the disintegration of accelerated nuclei seem to be also unable to create the peak since they cannot give the observed flux. If the

  17. The Kinematics of Kepler's Supernova Remnant as Revealed by Chandra

    NASA Astrophysics Data System (ADS)

    Vink, Jacco

    2008-12-01

    I have determined the expansion of the supernova remnant of SN 1604 (Kepler's supernova) based on archival Chandra ACIS-S observations made in 2000 and 2006. The measurements were done in several distinct energy bands, and were made for the remnant as a whole, and for six individual sectors. The average expansion parameter indicates that the remnant expands on average as r propto t0.5, but there are significant differences in different parts of the remnant: the bright northwestern part expands as r propto t0.35, whereas the rest of the remnant's expansion shows an expansion r propto t0.6. The latter is consistent with an explosion in which the outer part of the ejecta has a negative power law slope for density (ρ propto v-n) of n = 7, or with an exponential density profile [ρ propto exp (- v/ve) ]. The expansion parameter in the southern region, in conjunction with the shock radius, indicates a rather low value (<5 × 1050 erg) for the explosion energy of SN 1604 for a distance of 4 kpc. A higher explosion energy is consistent with the results if the distance is larger. The filament in the eastern part of the remnant, which is dominated by X-ray synchrotron radiation, seems to mark a region with a fast shock speed r propto t0.7, corresponding to a shock velocity of v = 4200 km s-1, for a distance to SN 1604 of 4 kpc. This is consistent with the idea that X-ray synchrotron emission requires shock velocities in excess of ~2000 km s-1. The X-ray-based expansion measurements reported are consistent with results based on optical and radio measurements but disagree with previous X-ray measurements based on ROSAT and Einstein observations.

  18. X-ray Observations of the Tycho Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Hughes, John P.

    2006-06-01

    In this presentation I summarize some key new findings from recent Chandra and XMM-Newton data on the remnant of the supernova (SN) observed by Tycho Brahe in 1572, which is widely believed to have been of Type Ia origin. Studies of the Tycho supernova remnant (SNR) at the current epoch address aspects of SN Ia physics, the evolution of young SNRs, and cosmic ray acceleration at high Mach-number shocks.Research on the Tycho SNR at Rutgers has been supported by Chandra grants GO3-4066X and AR5-6010X.

  19. A Compact Central Object in the Supernova Remnant Kesteven 79

    NASA Astrophysics Data System (ADS)

    Seward, F. D.; Slane, P. O.; Smith, R. K.; Sun, M.

    2003-02-01

    A Chandra X-ray observation has detected an unresolved source at the center of the supernova remnant Kes 79. The best single-model fit to the source spectrum is a blackbody with an X-ray luminosity of LX(0.3-8.0keV)=7×1033 ergs s-1. There is no evidence for a surrounding pulsar wind nebula. There are no cataloged counterparts at other wavelengths, but the absorption is high. The source properties are similar to the central source in Cas A even though the Kes 79 remnant is considerably older.

  20. High-energy Emission from the Composite Supernova Remnant MSH 15-56

    NASA Technical Reports Server (NTRS)

    Temim, Tea; Slane, Patrick; Castro, Daniel; Plucinsky, Paul; Gelfand, Joseph; Dickel, John R.

    2013-01-01

    MSH 1556 (G326.3-1.8) is a composite supernova remnant (SNR) that consists of an SNR shell and a displaced pulsar wind nebula (PWN) in the radio. We present XMM-Newton and Chandra X-ray observations of the remnant that reveal a compact source at the tip of the radio PWN and complex structures that provide evidence for mixing of the supernova (SN) ejecta with PWN material following a reverse shock interaction. The X-ray spectra are well fitted by a non-thermal power-law model whose photon index steepens with distance from the presumed pulsar, and a thermal component with an average temperature of 0.55 keV. The enhanced abundances of silicon and sulfur in some regions, and the similar temperature and ionization timescale, suggest that much of the X-ray emission can be attributed to SN ejecta that have either been heated by the reverse shock or swept up by the PWN. We find one region with a lower temperature of 0.3 keV that appears to be in ionization equilibrium.Assuming the Sedov model, we derive a number of SNR properties, including an age of 16,500 yr. Modeling of the gamma-ray emission detected by Fermi shows that the emission may originate from the reverse shock-crushed PWN.

  1. HIGH-ENERGY EMISSION FROM THE COMPOSITE SUPERNOVA REMNANT MSH 15-56

    SciTech Connect

    Temim, Tea; Slane, Patrick; Plucinsky, Paul P.; Castro, Daniel; Gelfand, Joseph; Dickel, John R.

    2013-05-01

    MSH 15-56 (G326.3-1.8) is a composite supernova remnant (SNR) that consists of an SNR shell and a displaced pulsar wind nebula (PWN) in the radio. We present XMM-Newton and Chandra X-ray observations of the remnant that reveal a compact source at the tip of the radio PWN and complex structures that provide evidence for mixing of the supernova (SN) ejecta with PWN material following a reverse shock interaction. The X-ray spectra are well fitted by a non-thermal power-law model whose photon index steepens with distance from the presumed pulsar, and a thermal component with an average temperature of 0.55 keV. The enhanced abundances of silicon and sulfur in some regions, and the similar temperature and ionization timescale, suggest that much of the X-ray emission can be attributed to SN ejecta that have either been heated by the reverse shock or swept up by the PWN. We find one region with a lower temperature of 0.3 keV that appears to be in ionization equilibrium. Assuming the Sedov model, we derive a number of SNR properties, including an age of 16,500 yr. Modeling of the {gamma}-ray emission detected by Fermi shows that the emission may originate from the reverse shock-crushed PWN.

  2. Radio spectral characteristics of the supernova remnant Puppis A and nearby sources

    NASA Astrophysics Data System (ADS)

    Reynoso, E. M.; Walsh, A. J.

    2015-08-01

    This paper presents a new study of the spectral index distribution of the supernova remnant (SNR) Puppis A. The nature of field compact sources is also investigated according to the measured spectral indices. This work is based on new observations of Puppis A and its surroundings performed with the Australia Telescope Compact Array in two configurations using the Compact Array Broad-band Backend centred at 1.75 GHz. We find that the global spectral index of Puppis A is α = -0.563 ± 0.013. Local variations have been detected, however this global index represents well the bulk of the SNR. At the SE, we found a pattern of parallel strips with a flat spectrum compatible with small-scale filaments, although not correlated in detail. The easternmost filament agrees with the idea that the SNR shock front is interacting with an external cloud. There is no evidence of the previously suggested correlation between emissivity and spectral index. A number of compact features are proposed to be evolved clumps of ejecta based on their spectral indices, although dynamic measurements are needed to confirm this hypothesis. We estimate precise spectral indices for the five previously known field sources, two of which are found to be double (one of them, probably triple), and catalogue 40 new sources. In the light of these new determinations, the extragalactic nature previously accepted for some compact sources is now in doubt.

  3. Adhesion behaviors on superhydrophobic surfaces.

    PubMed

    Zhu, Huan; Guo, Zhiguang; Liu, Weimin

    2014-04-18

    The adhesion behaviors of superhydrophobic surfaces have become an emerging topic to researchers in various fields as a vital step in the interactions between materials and organisms/materials. Controlling the chemical compositions and topological structures via various methods or technologies is essential to fabricate and modulate different adhesion properties, such as low-adhesion, high-adhesion and anisotropic adhesion on superhydrophobic surfaces. We summarize the recent developments in both natural superhydrophobic surfaces and artificial superhydrophobic surfaces with various adhesions and also pay attention to superhydrophobic surfaces switching between low- and high-adhesion. The methods to regulate or translate the adhesion of superhydrophobic surfaces can be considered from two perspectives. One is to control the chemical composition and change the surface geometric structure on the surfaces, respectively or simultaneously. The other is to provide external stimulations to induce transitions, which is the most common method for obtaining switchable adhesions. Additionally, adhesion behaviors on solid-solid interfaces, such as the behaviors of cells, bacteria, biomolecules and icing on superhydrophobic surfaces are also noticeable and controversial. This review is aimed at giving a brief and crucial overview of adhesion behaviors on superhydrophobic surfaces.

  4. Environmentally compliant adhesive joining technology

    SciTech Connect

    Tira, J.S.

    1996-08-01

    Adhesive joining offers one method of assembling products. Advantages of adhesive joining/assembly include distribution of applied forces, lighter weight, appealing appearance, etc. Selecting environmentally safe adhesive materials and accompanying processes is paramount in today`s business climate if a company wants to be environmentally conscious and stay in business. Four areas of adhesive joining (adhesive formulation and selection, surface preparation, adhesive bonding process, waste and pollution generation/cleanup/management) all need to be carefully evaluated before adhesive joining is selected for commercial as well as military products. Designing for six sigma quality must also be addressed in today`s global economy. This requires material suppliers and product manufacturers to work even closer together.

  5. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1985-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  6. Development of phosphorylated adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.; Jenkins, R. K.; Campbell, P. L.

    1983-01-01

    The synthesis of epoxy prepolymers containing phosphorus was carried out in such a manner as to provide adhesives containing at least 5 percent of this element. The purpose of this was to impart fire retardant properties to the adhesive. The two epoxy derivatives, bis(4-glycidyl-oxyphenyl)phenylphosphine oxide and bis(4-glycidyl-2-methoxyphenyl)phenylphosphonate, and a curing agent, bis(3-aminophenyl)methylphosphine oxide, were used in conjunction with one another and along with conventional epoxy resins and curing agents to bond Tedlar and Polyphenylethersulfone films to Kerimid-glass syntactic foam-filled honeycomb structures. Elevated temperatures are required to cure the epoxy resins with the phosphorus-contaning diamine; however, when Tedlar is being bonded, lower curing temperatures must be used to avoid shrinkage and the concomitant formation of surface defects. Thus, the phosphorus-containing aromatic amine curing agent cannot be used alone, although it is possible to use it in conjunction with an aliphatic amine which would allow lower cure temperatures to be used. The experimental epoxy resins have not provided adhesive bonds quite as strong as those provided by Epon 828 when compared in peel tests, but the differences are not very significant. It should be noted, if optimum properties are to be realized. In any case the fire retardant characteristics of the neat resin systems obtained are quite pronounced, since in most cases the self-extinguishing properties are evident almost instantly when specimens are removed from a flame.

  7. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  8. Adhesion barrier reduces postoperative adhesions after cardiac surgery.

    PubMed

    Kaneko, Yukihiro; Hirata, Yasutaka; Achiwa, Ikuya; Morishita, Hiroyuki; Soto, Hajime; Kobayahsi, Jotaro

    2012-06-01

    Reoperation in cardiac surgery is associated with increased risk due to surgical adhesions. Application of a bioresorbable material could theoretically reduce adhesions and allow later development of a free dissection plane for cardiac reoperation. Twenty-one patients in whom a bioresorbable hyaluronic acid-carboxymethylcellulose adhesion barrier had been applied in a preceding surgery underwent reoperations, while 23 patients underwent reoperations during the same period without a prior adhesion barrier. Blinded observers graded the tenacity of the adhesions from surgical video recordings of the reoperations. No excessive bleeding requiring wound reexploration, mediastinal infection, or other complication attributable to the adhesion barrier occurred. Multiple regression analysis showed that shorter duration of the preceding surgery, non-use of cardiopulmonary bypass in the preceding surgery, and use of the adhesion barrier were significantly associated with less tenacious surgical adhesions. The use of a bioresorbable material in cardiac surgery reduced postoperative adhesions, facilitated reoperation, and did not promote complications. The use of adhesion barrier is recommended in planned staged procedures and those in which future reoperation is likely.

  9. 6. OLD AND NEW TIOGA ROAD. NOTE REMNANTS OF OLD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. OLD AND NEW TIOGA ROAD. NOTE REMNANTS OF OLD ROAD ON LEFT. NOTE ROAD CUT ON CANYON WALL IN CENTER REAR. LOOKING NNE. GIS: N-37 56 19.5 / W-119 13 53.3 - Tioga Road, Between Crane Flat & Tioga Pass, Yosemite Village, Mariposa County, CA

  10. Remnant wharf with two bollards at the south end of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Remnant wharf with two bollards at the south end of row within Pan American Airways/Naval Air Transport Service/destroyer base site. View facing south-southeast. - U.S. Naval Base, Pearl Harbor, Pearl City Peninsula, Pearl City, Honolulu County, HI

  11. 15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. CYLINDRICAL FISH SCALER Remnants of the wire screen remain, through which the fish tumbled as the cylinder revolved. Note geared ring around cylinder, and the small drive shaft by which it was driven. - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA

  12. 15. VIEW SOUTH, DETAIL OF REMNANTS OF EAST SIDE BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. VIEW SOUTH, DETAIL OF REMNANTS OF EAST SIDE BRIDGE ABUTMENT - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  13. Modelling Hard Gamma-Ray Emission from Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    1999-01-01

    The observation by the CANGAROO (Collaboration of Australia and Nippon Gamma Ray Observatory at Outback) experiment of TeV emission from SN 1006, in conjunction with several instances of non-thermal X-ray emission from supernova remnants, has led to inferences of super-TeV electrons in these extended sources. While this is sufficient to propel the theoretical community in their modelling of particle acceleration and associated radiation, the anticipated emergence in the next decade of a number of new experiments probing the TeV and sub-TeV bands provides further substantial motivation for modellers. In particular, the quest for obtaining unambiguous gamma-ray signatures of cosmic ray ion acceleration defines a "Holy Grail" for observers and theorists alike. This review summarizes theoretical developments in the prediction of MeV-TeV gamma-rays from supernova remnants over the last five years, focusing on how global properties of models can impact, and be impacted by, hard gamma-ray observational programs, thereby probing the supernova remnant environment. Properties of central consideration include the maximum energy of accelerated particles, the density of the unshocked interstellar medium, the ambient magnetic field, and the relativistic electron-to-proton ratio. Criteria for determining good candidate remnants for observability in the TeV band are identified.

  14. Modelling Hard Gamma-Ray Emission from Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Baring, Matthew

    2000-01-01

    The observation by the CANGAROO experiment of TeV emission from SN 1006, in conjunction with several instances of non-thermal X-ray emission from supernova remnants, has led to inferences of super-TeV electrons in these extended sources. While this is sufficient to propel the theoretical community in their modelling of particle acceleration and associated radiation, the anticipated emergence in the next decade of a number of new experiments probing the TeV and sub-TeV bands provides further substantial motivation for modellers. In particular, the quest for obtaining unambiguous gamma-ray signatures of cosmic ray ion acceleration defines a "Holy Grail" for observers and theorists alike. This review summarizes theoretical developments in the prediction of MeV-TeV gamma-rays from supernova remnants over the last five years, focusing on how global properties of models can impact, and be impacted by, hard gamma-ray observational programs, thereby probing the supernova remnant environment. Properties of central consideration include the maximum energy of accelerated particles, the density of the unshocked interstellar medium, the ambient magnetic field, and the relativistic electron-to-proton ratio. Criteria for determining good candidate remnants for observability in the TeV band are identified.

  15. Meteorological Station, interior with collapsed roof showing remnant wooden equipment ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Meteorological Station, interior with collapsed roof showing remnant wooden equipment switch box on east wall; view southeast - Fort McKinley, Meteorological Station, East side of Weymouth Way, approximately 225 feet south of Cove Side Drive, Great Diamond Island, Portland, Cumberland County, ME

  16. Hot interstellar tunnels. 1: Simulation of interacting supernova remnants

    NASA Technical Reports Server (NTRS)

    Smith, B. W.

    1976-01-01

    The theory required to build a numerical simulation of interacting supernova remnants is developed. The hot cavities within a population of remnants will become connected, with varying ease and speed, for a variety of assumed conditions in the outer shells of old remnants. Apparently neither radiative cooling nor thermal conduction in a large-scale galactic magnetic field can destroy hot cavity regions, if they grow, faster than they are reheated by supernova shock waves, but interstellar mass motions disrupt the contiguity of extensive cavities necessary for the dispersal of these shocks over a wide volume. Monte Carlo simulations show that a quasi-equilibrium is reached in the test space within 10 million yrs of the first supernova and is characterized by an average cavity filling fraction of the interstellar volume. Aspects of this equilibrium are discussed for a range of supernova rates. Two predictions are not confirmed within this range: critical growth of hot regions to encompass the entire medium, and the efficient quenching of a remnant's expansion by interaction with other cavities.

  17. Steam or water connection with remnant of concrete basin in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Steam or water connection with remnant of concrete basin in foreground. Pipe connection located approximately 6' east of metal stairs leading to Bright Angel Lodge. Dry laid retaining wall in background. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  18. 8. VIEW OF REMNANTS OF COULTERVILLE ROAD BELOW FORESTA. NOTE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF REMNANTS OF COULTERVILLE ROAD BELOW FORESTA. NOTE ASPHALT AT LEFT CENTER. NOTE RETAINING WALL AT RIGHT REAR. LOOKING NW. GIS: N-37 42 40.6 / W-119 43 27.6 - Coulterville Road, Between Foresta & All-Weather Highway, Yosemite Village, Mariposa County, CA

  19. Limb-threatening ischemia secondary to a congenital acromioclavicular remnant.

    PubMed

    Enlow, Jonathan M; McGregor, Walter E

    2009-07-01

    Upper extremity vascular compromise from thoracic outlet syndrome is rare and is usually the result of a "cervical rib," anterior scalene muscle abnormality, or clavicular trauma. We report a case of acute axillary artery thrombosis secondary to a congenital acromioclavicular remnant in a 40-year-old woman.

  20. General exterior view showing remnants of loading dock at three ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General exterior view showing remnants of loading dock at three main doors, view to north - Charlestown Navy Yard, Oxygen Plant, Midway along northern boundary of Charlestown Navy Yard, on Little Mystic Channel, near junction of Eighteenth Street & Fourth Avenue, Boston, Suffolk County, MA

  1. Study of the Composite Supernova Remnant MSH 11-62

    NASA Astrophysics Data System (ADS)

    Harrus, Ilana M.; Hughes, John P.; Slane, Patrick O.

    1998-05-01

    We present the analysis of the X-ray data collected during an observation of the supernova remnant (SNR) MSH 11-62 by the Advanced Satellite for Cosmology and Astrophysics (ASCA). We show that MSH 11-62 is a composite remnant whose X-ray emission comes from two distinct contributions. Nonthermal, synchrotron emission, localized to a region of radius ~3' (consistent with a point source), dominates the total flux above 2 keV. A second contribution comes from a thermal component, extended up to a radius of ~6' and detected only at energies below 2 keV. The spatial and spectral analyses imply the presence of a neutron star losing energy at a rate of about Ė~1036-1037 ergs s-1. No pulsed emission is detected, and we set a limit on the pulsed fraction of ~10%. This is consistent with the lack of a radio pulsar in the remnant, which may indicate that the pulsed emission from the rapidly rotating compact object that should be powering the synchrotron nebula is beamed, and our viewing direction is unfavorable. In either event, the central neutron star deposits much of its spin-down energy into the surrounding synchrotron nebula where, through direct imaging with broadband satellites such as ASCA, it is possible to study the energetics and evolution of the compact remnant.

  2. Satellite Movie Shows Hurricane Dolores' Remnants Bring Rains to U.S. Southwest

    NASA Video Gallery

    This animation of images captured July 17 to 22 from NOAA's GOES-West satellite shows Hurricane Dolores' remnants streaming over the southwestern U.S. The remnants dropped heavy rainfall in Califor...

  3. Young Remnants of Type Ia Supernovae and Their Progenitors: A Study of SNR G1.9+0.3

    NASA Astrophysics Data System (ADS)

    Chakraborti, Sayan; Childs, Francesca; Soderberg, Alicia

    2016-03-01

    SNe Ia, with their remarkably homogeneous light curves and spectra, have been used as standardizable candles to measure the accelerating expansion of the universe. Yet, their progenitors remain elusive. Common explanations invoke a degenerate star (white dwarf) that explodes upon almost reaching the Chandrasekhar limit, by either steadily accreting mass from a companion star or violently merging with another degenerate star. We show that circumstellar interaction in young Galactic supernova remnants can be used to distinguish between these single and double degenerate (DD) progenitor scenarios. Here we propose a new diagnostic, the surface brightness index, which can be computed from theory and compared with Chandra and Very Large Array (VLA) observations. We use this method to demonstrate that a DD progenitor can explain the decades-long flux rise and size increase of the youngest known galactic supernova remnant (SNR), G1.9+0.3. We disfavor a single degenerate scenario for SNR G1.9+0.3. We attribute the observed properties to the interaction between a steep ejecta profile and a constant density environment. We suggest using the upgraded VLA, ASKAP, and MeerKAT to detect circumstellar interaction in the remnants of historical SNe Ia in the Local Group of galaxies. This may settle the long-standing debate over their progenitors.

  4. A 3D numerical model for Kepler's supernova remnant

    NASA Astrophysics Data System (ADS)

    Toledo-Roy, J. C.; Esquivel, A.; Velázquez, P. F.; Reynoso, E. M.

    2014-07-01

    We present new 3D numerical simulations for Kepler's supernova remnant. In this work we revisit the possibility that the asymmetric shape of the remnant in X-rays is the product of a Type Ia supernova explosion which occurs inside the wind bubble previously created by an AGB companion star. Due to the large peculiar velocity of the system, the interaction of the strong AGB wind with the interstellar medium results in a bow shock structure. In this new model we propose that the AGB wind is anisotropic, with properties such as mass-loss rate and density having a latitude dependence, and that the orientation of the polar axis of the AGB star is not aligned with the direction of motion. The ejecta from the Type Ia supernova explosion is modelled using a power-law density profile, and we let the remnant evolve for 400 yr. We computed synthetic X-ray maps from the numerical results. We find that the estimated size and peculiar X-ray morphology of Kepler's supernova remnant are well reproduced by considering an AGB mass-loss rate of 10-5 M⊙ yr-1, a wind terminal velocity of 10 km s-1, an ambient medium density of 10-3 cm-3 and an explosion energy of 7 × 1050 erg. The obtained total X-ray luminosity of the remnant in this model reaches 6 × 1050 erg, which is within a factor of 2 of the observed value, and the time evolution of the luminosity shows a rate of decrease in recent decades of ˜2.4 per cent yr-1 that is consistent with the observations.

  5. Arachnids Secrete a Fluid over Their Adhesive Pads

    PubMed Central

    Peattie, Anne M.; Dirks, Jan-Henning; Henriques, Sérgio; Federle, Walter

    2011-01-01

    Background Many arachnids possess adhesive pads on their feet that help them climb smooth surfaces and capture prey. Spider and gecko adhesives have converged on a branched, hairy structure, which theoretically allows them to adhere solely by dry (solid-solid) intermolecular interactions. Indeed, the consensus in the literature is that spiders and their smooth-padded relatives, the solifugids, adhere without the aid of a secretion. Methodology and Principal Findings We investigated the adhesive contact zone of living spiders, solifugids and mites using interference reflection microscopy, which allows the detection of thin liquid films. Like insects, all the arachnids we studied left behind hydrophobic fluid footprints on glass (mean refractive index: 1.48–1.50; contact angle: 3.7–11.2°). Fluid was not always secreted continuously, suggesting that pads can function in both wet and dry modes. We measured the attachment forces of single adhesive setae from tarantulas (Grammostola rosea) by attaching them to a bending beam with a known spring constant and filming the resulting deflection. Individual spider setae showed a lower static friction at rest (26%±2.8 SE of the peak friction) than single gecko setae (Thecadactylus rapicauda; 96%±1.7 SE). This may be explained by the fact that spider setae continued to release fluid after isolation from the animal, lubricating the contact zone. Significance This finding implies that tarsal secretions occur within all major groups of terrestrial arthropods with adhesive pads. The presence of liquid in an adhesive contact zone has important consequences for attachment performance, improving adhesion to rough surfaces and introducing rate-dependent effects. Our results leave geckos and anoles as the only known representatives of truly dry adhesive pads in nature. Engineers seeking biological inspiration for synthetic adhesives should consider whether model species with fluid secretions are appropriate to their design goals

  6. INDEXING MECHANISM

    DOEpatents

    Kock, L.J.

    1959-09-22

    A device is presented for loading and unloading fuel elements containing material fissionable by neutrons of thermal energy. The device comprises a combination of mechanical features Including a base, a lever pivotally attached to the base, an Indexing plate on the base parallel to the plane of lever rotation and having a plurality of apertures, the apertures being disposed In rows, each aperture having a keyway, an Index pin movably disposed to the plane of lever rotation and having a plurality of apertures, the apertures being disposed in rows, each aperture having a keyway, an index pin movably disposed on the lever normal to the plane rotation, a key on the pin, a sleeve on the lever spaced from and parallel to the index pin, a pair of pulleys and a cable disposed between them, an open collar rotatably attached to the sleeve and linked to one of the pulleys, a pin extending from the collar, and a bearing movably mounted in the sleeve and having at least two longitudinal grooves in the outside surface.

  7. An ATCA radio-continuum study of the Small Magellanic Cloud - III. Supernova remnants and their environments

    NASA Astrophysics Data System (ADS)

    Filipović, M. D.; Payne, J. L.; Reid, W.; Danforth, C. W.; Staveley-Smith, L.; Jones, P. A.; White, G. L.

    2005-11-01

    A total of 717 sources from the Australia Telescope Compact Array (ATCA) catalogue of the Small Magellanic Cloud (SMC) have been classified in Paper II (of this series) by Payne et al. Here, we present a statistical analysis of all 16 confirmed supernova remnants (SNRs) and five new candidate remnants. Included is a detailed discussion of the latter and three other sources that have some SNR characteristics. We have also found a new microquasar candidate (ATCA J005523-721055) in addition to ATCA J004718-723947 reported in Paper II. Source diameter comparisons suggest that SNRs as a group are of similar size in radio, optical and X-ray with surface brightness values in the range of Galactic remnants. Remnant spectral indices, α[defined as Sν~να, with Sν (flux density) and ν (frequency)], have a mean of -0.63 [standard deviation (s.d.) = 0.43] and ROSAT X-ray hardness ratios confirm them to be soft X-ray sources compared to background objects. We could not find any meaningful correlation between SNR surface brightness and diameter; we also discuss the number-diameter relation. A Venn diagram summarizes that most SNRs emit radiation in all three of the radio, optical and X-ray domains. HII region diameter comparisons between radio and optical sources show them to be a very diverse group that defies any simple relationship, preventing any meaningful calculation of flux density or spectral index. To better understand environments containing SNRs, we have scaled Hα images of four SMC regions and subtracted their flux from the ATCA 2.37-GHz radio image. These 2.37 GHz-Hα subtraction (or difference) images reveal some new sources with predominantly non-thermal emission, exposing SNRs confused with HII regions.

  8. [Adhesive cutaneous pharmaceutical forms].

    PubMed

    Gafiţanu, E; Matei, I; Mungiu, O C; Pavelescu, M; Mîndreci, I; Apostol, I; Ionescu, G

    1989-01-01

    The adhesive cutaneous pharmaceutical forms aimed to local action release the drug substance in view of a dermatological, traumatological, antirheumatic, cosmetic action. Two such preparations were obtained and their stability, consistency and pH were determined. The "in vitro" tests of their bioavailability revealed the dynamics of calcium ions release according to the associations of each preparation. The bioavailability determined by evaluating the pharmacological response demonstrated the antiinflammatory action obtained by the association of calcium ions with the components extracted from poplar muds. The therapeutical efficiency of the studied preparations has proved in the treatment of some sport injuries.

  9. Puerperal endometritis and intrauterine adhesions.

    PubMed

    Polishuk, W Z; Anteby, S O; Weinstein, D

    1975-08-01

    The role of puerperal endometritis in intrauterine adhesion formation was studied by hysterography in 171 women who had cesarean sections. Of 28 patients who developed significant endometritis, only one developed intracervical adhesions. In the control group of 143 cases, there was also only one such case. Endometritis alone apparently does not play a significant role in intrauterine and endocervical adhesion formation. The possible role of placental fibroblasts in preventing endometrial regeneration is discussed. PMID:1158622

  10. Adhesion properties of gecko setae

    NASA Astrophysics Data System (ADS)

    Hill, Ginel; Peattie, Anne; Daniels, Roxanne; Full, Robert; Kenny, Thomas

    2005-03-01

    Millions of keratin hairs on gecko feet, called setae, act as a spectacular dry adhesive. Each seta branches into hundreds of smaller fibers that terminate in spatula-shaped ends. Morphological differences between the setae from different gecko species are suspected to affect both single-seta and whole-animal adhesion properties. Single-seta adhesive force measurements made using a MEMS piezoresistive cantilever capable of two-axis measurements are presented.

  11. Second Epoch Hubble Space Telescope Imaging of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Sankrit, Ravi; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.; Patnaude, Daniel; Raymond, John C.; Reynolds, Stephen P.; Williams, Brian J.

    2015-01-01

    We have obtained new HST/WFC3 images of Kepler's supernova remnant in H-alpha (F656N) and [N II] (F658N) emission line filters. The bright radiative shocks in dense clumps are detected in both filters, while non-radiative shocks are seen as faint filaments only in the H-alpha image. Most of these Balmer filaments lie around the periphery of the remnant where the blast wave encounters partially neutral interstellar gas. We compare the new images with HST/ACS images taken nearly 10 years previously, and find that these filaments tracing the forward shock have moved 0.6"-0.9" between the two epochs. Assuming a distance of 4 kpc to the remnant, these proper motions correspond to shock velocities of 1160-1740 km/s, which are consistent with the published values, 1550-2000 km/s (e.g. Blair et al. 1991, ApJ 366, 484). We also find a few Balmer filaments with highly non-radial proper motions. In one particularly interesting case in the projected interior of the remnant, SE of the center, the shock appears to have wrapped around a sharp density enhancement and moved about 0.3" in the period between the observations.The images allow us to study the evolution of the shock around an ejecta knot, which is punching through the remnant boundary in the northwest. The forward shock, visible as an arcuate Balmer filament, has moved about 1". At the trailing edges, the system of radiative knots formed by Rayleigh-Taylor instabilities have undergone significant changes - some knots have disappeared, new ones have appeared, and many have changed in brightness. Elsewhere in the remnant we find changes in the relative intensities of many small, bright knots over the 10 year baseline, indicating the short radiative lifetimes of these features.This work has been supported in part by grant HST-GO-12885 to the Universities Space Research Association.

  12. Topographically Tuning Polymer Adhesion

    NASA Astrophysics Data System (ADS)

    Crosby, Alfred

    2003-03-01

    Nature often uses geometry on micro and nano length scales to systematically tailor performance in multivariable environments. A great example, which has received much attention recently, is the foot of a gecko. The gecko's foot is covered with hundreds of thousands of "hair"-like protrusions which dictate a gecko's precise control of adhesion through van der Waals forces.(1) In our research, we fabricate controlled structures ranging from the nano to micro length scales on elastomeric surfaces. Our initial results are based on the topography of spherical caps and high-aspect ratio posts that decorate the surface of polydimethylsiloxane layers. Based on initial calculations, we demonstrate how the aspect ratio and inter-feature spacing greatly affects the near-surface compliance, thus impacting the processes of interface formation. The density and shape of the features are also shown to enhance the prevention of interfacial failure. These results are relevant for the refinement of the soft lithography processing technique, the development of smart adhesives, and the fabrication of bonding sites for biological implants. (1) Autumn, K.; Liang, Y.A.; Hsieh, S.T.; Zesch, W.; Chan, W.P.; Kenny,T.W.; Fearing, R.; Full, R.J. Nature 2000, 405, 681-685.

  13. Principles of adhesion.

    PubMed

    Baier, R E

    1992-01-01

    Understanding interfacial phenomena has been of direct relevance and practical benefit to extending the use of dental adhesives. Both surface physics, which describes properties of the inorganic materials' interfacial zones from their actual phase boundaries toward the bulk phases of the solids, and surface chemistry, which describes phenomena at the solid/biological interface and beyond it into the variable organic environment, have been important. High-energy materials include solids that are very hard, have high melting points, strong intermolecular forces, and basically crystalline structures, such as dental enamel. Low-energy materials, such as dentinal collagen, salivary films, and the organic resins of restorative materials, are softer, lower melting, and have weaker intermolecular forces, poorer crystallinity, and surface energies generally less than 100 ergs/cm. It has been a properly renewed emphasis on wetting of dental surfaces and their modification by primer coats, displacing or mixing with water and adsorbed proteinaceous films, that has promoted the success of many recently developed fourth-generation dentin adhesives. Their improved wettability for biological phases correlates directly with their better infiltration and anchoring of composites.

  14. Analysis and testing of adhesive bonds

    NASA Technical Reports Server (NTRS)

    Anderson, G. P.; Bennett, S. J.; Devries, K. L.

    1977-01-01

    An adhesive fracture mechanics approach is described with reference to the identification and design of the best tests for evaluating a given adhesive, the definition of the most meaningful fundamental parameters by which adhesives might be characterized, and the application of these parameters to the design of joints and to the prediction of their performance. Topics include standard adhesive test techniques, the theory of adhesive fracture, and adhesive fracture energy tests. Analytical methods and computer techniques for adhesive bonding, chemical and physical aspects of adhesive fracture, and specific applications and aspects of adhesive fracture mechanics are discussed.

  15. Stickiness--some fundamentals of adhesion.

    PubMed

    Gay, Cyprien

    2002-12-01

    We review some adhesion mechanisms that have been understood in the field of synthetic adhesives, and more precisely for adhesives that adhere instantaneously (a property named tackiness) and whose adhesive strength usually depends on the applied pressure (pressure-sensitive adhesives). The discussion includes effects of surface roughness, elasticity, cavitation, viscous and elastic fingering, substrate flexibility. PMID:21680396

  16. Stickiness--some fundamentals of adhesion.

    PubMed

    Gay, Cyprien

    2002-12-01

    We review some adhesion mechanisms that have been understood in the field of synthetic adhesives, and more precisely for adhesives that adhere instantaneously (a property named tackiness) and whose adhesive strength usually depends on the applied pressure (pressure-sensitive adhesives). The discussion includes effects of surface roughness, elasticity, cavitation, viscous and elastic fingering, substrate flexibility.

  17. The VERITAS Supernova Remnant / Pulsar Wind Nebula Observation Program

    NASA Astrophysics Data System (ADS)

    Humensky, Thomas Brian; VERITAS Collaboration

    2011-09-01

    Supernova remnants and pulsar wind nebulae together constitute the vast majority of galactic gamma-ray sources seen at TeV energies. Supernova remnants are widely considered to be the strongest candidate for the source of cosmic rays below the knee around 1015 eV. Pulsar wind nebulae, powered by the spin-down energy released by pulsars and visible due to synchrotron and inverse Compton radiation emitted by their constituent electrons, comprise one of the most populous VHE gamma-ray source classes. VERITAS, an array of four imaging Cherenkov telescopes located at the Whipple Observatory in southern Arizona, has made significant contributions to the study of both classes of objects. This poster will summarize the results of this observation program and prospects for the future.

  18. Is the Eagle Nebula powered by a hidden supernova remnant ?

    NASA Astrophysics Data System (ADS)

    Boulanger, Francois

    2008-10-01

    Spitzer observations of the Eagle nebula (M16) reveal the presence of a large (8 pc diameter) shell of dust heated to anomalously high temperatures. Modeling of dust excitation shows that the shell emission cannot be powered by the cluster UV radiation but that it can be accounted for by collisionally heated dust in a young (a few 1000 yrs) supernova remnant. We have re-analyzed deep Chandra observations that show diffuse emission consistent with this hypothesis, but also with galactic ridge emission. We propose a 50 ksec XMM observation to probe the spatial extent of the diffuse X-ray emission beyond the Spitzer shell. Absence of emission outside of this shell will strongly support the supernova remnant interpretation

  19. Radio evolution of the remnant of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    Zanardo, Giovanna

    Radio supernovae result from the collision between a supernova (SN) shock and the progenitor's circumstellar medium (CSM). Supernova 1987A in the Large Magellanic Cloud, as the only nearby core-collapse supernova observed with a telescope since its early stages, has allowed unique studies of the SN-CSM interaction and the complex structure of the resulting emission. This thesis investigates the evolution of the remnant of SN 1987A, as the shock wave impacts the dense CSM in the equatorial ring, and the possible presence of a compact object in the remnant interior, using new data from the Australia Telescope Compact Array, the Atacama Large Millimeter/submillimeter Array, the Australian Long Baseline Array, and the Parkes telescope.

  20. No cold dust within the supernova remnant Cassiopeia A.

    PubMed

    Krause, Oliver; Birkmann, Stephan M; Rieke, George H; Lemke, Dietrich; Klaas, Ulrich; Hines, Dean C; Gordon, Karl D

    2004-12-01

    A large amount (about three solar masses) of cold (18 K) dust in the prototypical type II supernova remnant Cassiopeia A was recently reported. It was concluded that dust production in type II supernovae can explain how the large quantities (approximately 10(8) solar masses) of dust observed in the most distant quasars could have been produced within only 700 million years after the Big Bang. Foreground clouds of interstellar material, however, complicate the interpretation of the earlier submillimetre observations of Cas A. Here we report far-infrared and molecular line observations that demonstrate that most of the detected submillimetre emission originates from interstellar dust in a molecular cloud complex located in the line of sight between the Earth and Cas A, and is therefore not associated with the remnant. The argument that type II supernovae produce copious amounts of dust is not supported by the case of Cas A, which previously appeared to provide the best evidence for this possibility.

  1. Supernova remnant revolution in an inhomogeneous medium. I - Numerical models

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; Mckee, C. F.; Ostriker, J. P.

    1981-01-01

    The first numerical simulations of supernova remnant evolution in an inhomogeneous gas are presented. Evolution in the lowest density substrate (the intercloud) is assumed to be spherically symmetric with a large intercloud filling factor and many dense regions (clouds) within the remnant; however, mass momentum and energy transfer between cloud and intercloud are included and the position and morphology of individual clouds tracked. Evolution is considered in several different models of the interstellar medium, both those in which the intercloud gas is diffuse (0.001 to 0.01/cu cm) and those in which it is relatively dense (n approximately 0.3/cu cm) under a variety of assumptions about the efficiency of thermal evaporation from the clouds into the intercloud medium.

  2. The broad-line region as supernova remnants

    NASA Astrophysics Data System (ADS)

    Tenorio-Tagle, Guillermo; Terlevich, Roberto; Franco, Jose; Melnick, Jorge

    Supernova remnants evolving in a dense medium (n about 10**7 percc) become strongly radiative while still expanding at velocities of several thousands of km/s. Radiative cooling becomes important well before the thermalization of the ejecta is completed and makes the remnant miss the Sedov adiabatic track. As a result, the shocked matter undergoes a rapid condensation behind both the leading and the reverse shocks. Two concentric, high-density, fast moving thin shells are then formed. Both cool dense shells, as well as the freely expanding ejecta, and a section of the still dynamically unperturbed interstellar gas, are irradiated and ionized by the photon field produced by the radiative shocks. The emitted spectrum has emission-line ratios similar to those observed in the broad line region of low-luminosity active galactic nuclei. Our model combines analytic and numerical hydrodynamic simulations, together with static photoionization calculations to reproduce the observed properties of these broad-line regions.

  3. Distant Supernova Remnant Imaged by Chandra's High Resolution Camera

    NASA Astrophysics Data System (ADS)

    1999-09-01

    The High Resolution Camera (HRC), one of the two X-ray cameras on NASA's Chandra X-ray Observatory, was placed into the focus for the first time on Monday, August 30. The first target was LMC X-1, a point-like source of X rays in the Large Magellanic Cloud. The Large Magellanic Cloud, a companion galaxy to the Milky Way, is 160,000 light years from Earth. After checking the focus with LMC X-1, Chandra observed N132D, a remnant of an exploded star in the Large Magellanic Cloud. "These were preliminary test observations," emphasized Dr. Stephen Murray, of the Harvard-Smithsonian Center for Astrophysics, principal investigator for the High Resolution Camera. "But we are very pleased with the results. All indications are that the HRC will produce X-ray images of unprecedented clarity." The N132D image shows a highly structured remnant, or shell, of 10-million-degree gas that is 80 light years across. Such a shell in the vicinity of the Sun would encompass more than fifty nearby stars. The amount of material in the N132D hot gas remnant is equal to that of 600 suns. The N132D supernova remnant appears to be colliding with a giant molecular cloud, which produces the brightening on the southern rim of the remnant. The molecular cloud, visible with a radio telescope, has the mass of 300,000 suns. The relatively weak x-radiation on the upper left shows that the shock wave is expanding into a less dense region on the edge of the molecular cloud. A number of small circular structures are visible in the central regions and a hint of a large circular loop can be seen in the upper part of the remnant. Whether the peculiar shape of the supernova remnant can be fully explained in terms of these effects, or whether they point to a peculiar cylindrically shaped explosion remains to be seen. -more- "The image is so rich in structure that it will take a while to sort out what is really going on," Murray said. "It could be multiple supernovas, or absorbing clouds in the vicinity of the

  4. Radio structure of the remnant of Tycho's supernova (SN 1572)

    SciTech Connect

    Dickel, J.R.; Van breugel, W.J.M.; Strom, R.G. Lawrence Livermore National Laboratory, Livermore, CA Netherlands Foundation for Research in Astronomy, Dwingeloo )

    1991-06-01

    The radio emission from the remnant of Tycho's supernova of 1572 arises in a nearly circular, clumpy shell. A very distinct, thin bright rim just outside the main shell can be seen around most of the periphery of the remnant. The outer edge of radio emission, usually defined by this bright rim, coincides perfectly with the outer X-ray boundary. Most of the emission is polarized by a modest amount, with the outer rim particularly prominent. Observations at several wavelengths are used to map out the rotation measure at high angular resolution, and determine the intrinsic magnetic field direction. The magnetic field shows a somewhat cellular pattern but with a net radial orientation and a generally fairly low degree of polarization. 44 refs.

  5. Effect of adhesive thickness on adhesively bonded T-joint

    NASA Astrophysics Data System (ADS)

    Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

    2013-12-01

    The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

  6. Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

    PubMed

    Li, Yasong; Gates, Byron D; Menon, Carlo

    2015-08-01

    The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

  7. Stretchable, adhesion-tunable dry adhesive by surface wrinkling.

    PubMed

    Jeong, Hoon Eui; Kwak, Moon Kyu; Suh, Kahp Y

    2010-02-16

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (approximately 10.8 N/cm(2)) and shear adhesion (approximately 14.7 N/cm(2)) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of approximately 3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of approximately 0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment.

  8. Recurrent Ectopic Pregnancy in the Tubal Remnant after Salpingectomy

    PubMed Central

    Samiei-Sarir, Bahareh; Diehm, Christopher

    2013-01-01

    We present two cases of ectopic pregnancy located within the remnant tube following ipsilateral salpingectomy. This particular pathology is rare and yet has significant consequences for the patient, with mortality rates 10–15 times higher than other ectopic pregnancies. It demonstrates that salpingectomy does not exclude ectopic pregnancy on the ipsilateral side. We suggest careful clinical consideration and bring attention to the current surgical technique. PMID:24151570

  9. Cosmic Ray and Tev Gamma Ray Generation by Quasar Remnants

    NASA Technical Reports Server (NTRS)

    Boldt, Elihu; Loewenstein, Michael; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Results from new broadband (radio to X-ray) high-resolution imaging studies of the dormant quasar remnant cores of nearby giant elliptical galaxies are now shown to permit the harboring of compact dynamos capable of generating the highest energy cosmic ray particles and associated curvature radiation of TeV photons. Confirmation would imply a global inflow of interstellar gas all the way to the accretion powered supermassive black hole at the center of the host galaxy.

  10. Midbody remnant licenses primary cilia formation in epithelial cells.

    PubMed

    Ott, Carolyn M

    2016-08-01

    Tethered midbody remnants dancing across apical microvilli, encountering the centrosome, and beckoning forth a cilium-who would have guessed this is how polarized epithelial cells coordinate the end of mitosis and the beginning of ciliogenesis? New evidence from Bernabé-Rubio et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201601020) supports this emerging model. PMID:27482049

  11. Without Remnant Movement, MGs Are Context-Free

    NASA Astrophysics Data System (ADS)

    Kobele, Gregory M.

    Minimalist grammars offer a formal perspective on a popular linguistic theory, and are comparable in weak generative capacity to other mildly context sensitive formalism. Minimalist grammars allow for the straightforward definition of so-called remnant movement constructions, which have found use in many linguistic analyses. It has been conjectured that the ability to generate this kind of configuration is crucial to the super-context-free expressivity of minimalist grammars. This conjecture is here proven.

  12. Radio-Quiet Pulsars and Point Sources in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Helfand, David

    2002-04-01

    Since Baade and Zwicky made their prescient remark identifying the central blue star in the Crab Nebula as a neutron star, this pulsar's period has increased by 0.9 msec, turning 10^48 ergs of rotational kinetic energy into a relativistic wind that has been deposited in its surroundings. This makes the compact remnant of the supernova of 1054 AD highly conspicuous. It also makes this remnant highly anomalous. Nowhere else in the Galaxy does such a luminous young pulsar exists, despite the fact that at least half a dozen core-collapse supernovae have occurred since the Crab's birth. Indeed, the newly discovered central object in Cas A is four orders of magnitude less luminous in the X-ray band. While the Chandra and XMM-Newton Observatories are discovering an increasing number of Crab-like synchrotron nebulae (albeit, far less luminous than the prototype), they are also revealing X-ray point sources inside supernova remnants that lack detectable radio pulses and show no evidence of a relativistic outflow to power a surrounding nebula. I will provide an inventory of these objects, discuss whether or not truly radio-silent young neutron stars exist, and speculate on the emission mechanisms and power sources which make such objects shine. I will conclude with a commentary on the implications of this population for the distributions of pulsar birth parameters such as spin period, magnetic field strength, and space velocity, as well as offer a glimpse of what future observations might reveal about the demographics of core-collapse remnants.

  13. Increased sodium transport by cortical collecting tubules from remnant kidneys.

    PubMed

    Vehaskari, V M; Hering-Smith, K S; Klahr, S; Hamm, L L

    1989-07-01

    To determine whether intrinsic changes in cortical collecting tubule (CCT) transport contribute to the maintenance of sodium and acid-base balance after loss of renal mass, we studied transport functions in isolated perfused CCT from rabbit remnant kidneys. The rabbits were sacrificed three weeks after surgical reduction of renal mass (by 3/4 to 7/8) at which time they were mildly azotemic but had no systemic electrolyte or acid-base disturbances. When perfused by standard methods in vitro, CCT from remnant kidneys exhibited sodium transport rates (lumen-to-bath 22Na-flux) approximately twice as high as those in CCT from control animals (111 +/- 19 vs. 54 +/- 7 pmol/min mm, P less than 0.02). A similar difference was present in the ouabain-sensitive sodium fluxes (81 +/- 16 vs. 39 +/- 8 pmol/min mm, P less than 0.05). In contrast, there were no significant differences in net bicarbonate transport. Significant hypertrophy of the remnant kidney CCT was reflected by 30 to 45% increases in tubule diameters. To examine the possible role of differences in food intake, we studied a separate group of weight-matched, pair-fed sham-operated and remnant kidney rabbits. Similar differences in total and ouabain-sensitive 22Na-flux, and in tubule size persisted in the pair-fed animals. A dissociation between active sodium transport and tubule hypertrophy was documented in the outer medullary collecting tubule: despite the lack of active sodium transport, hypertrophy was present. Our studies show that loss of renal mass results in a selective augmentation of certain transport processes in the CCT, implying selective or specific signals and mechanisms. PMID:2811058

  14. The Unusual Young Supernova Remnant Population in M83

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Dopita, M. A.; Ghavamian, P.; Kuntz, K. D.; Long, K. S.; Plucinsky, P. P.; Soria, R.; Winkler, P. F.

    2014-01-01

    The face-on grand design spiral galaxy M83 (d=4.6 Mpc) is a veritable supernova factory, having generated six known SNe in less than 100 years. Hence, one might expect of order 60 or more supernova remnants (SNRs) less than a thousand years old that might shed light on the poorly understood ejecta-dominated phase of early SNR evolution, as well as many more older, ISM-dominated remnants that should still be visible. We are conducting a multi-wavelength Chandra/Hubble/ground-based campaign to find and characterize the SNRs in M83, concentrating especially on the younger population. HST/WFC3 emission-line data for seven fields covering the bulk of the bright optical disk have allowed us to identify ~50 optical SNR candidates with angular sizes below 0.5” (<11 pc), many with corresponding Chandra X-ray counterparts. However, with the singular exception of the remnant of SN1957D, we are not finding the expected population of ejecta-dominated young SNRs. Rather, most of the young SNRs appear to have quickly evolved into the radiative phase. Gemini-S GMOS spectra of selected objects confirm the lack of observed high velocities or obvious ejecta-enhancement of abundances. This unexpected result implies that the CSM/ISM environments for most young remnants in M83 are very dense, perhaps due in part to the super-solar metal abundances in much of this galaxy. We will show representative data from all relevant data sets that lead us to this conclusion. This work is supported in part by STScI grant HST-GO-12513.01-A and Chandra grant SAO-GO1-12115C to Johns Hopkins University.

  15. Study of the Composite Remnant MSH 11--62

    NASA Astrophysics Data System (ADS)

    Harrus, I. M.; Hughes, J. P.; Slane, P. O.

    1996-12-01

    We present an analysis of the X-ray data collected during an observation of the supernova remnant (SNR) MSH 11-62 by the Advanced Satellite for Cosmology and Astrophysics (ASCA). We show that MSH 11-62 is a composite remnant whose X-ray emission comes from two distinct contributions: a nonthermal, synchrotron emission, dominating the total flux above 2 keV, and localized to a region of radius 3(') (consistent with a point source) and a thermal component, extended up to a radius of ~ 5(') and detected only at energies below 2 keV. The spatial and spectral analysis imply, in the context of empirical models, the presence of a neutron star, losing energy at a rate of about dot E ~ 2.2*E(36) ergs s(-1) . The period of the neutron star is estimated to be around 0.380 sec although our timing analysis leads to only an upper limit to the pulsed fraction of ~ 10%. This is consistent with the lack of a radio pulsar in the remnant, which may be due to insufficient sensitivity of published searches or may indicate that the pulsed emission from the rapidly rotating compact object that should be powering the synchrotron nebula is beamed and our viewing direction is unfavorable. In either event, the central neutron star deposits much of its spin-down energy into the surrounding synchrotron nebula where, through direct imaging with broadband satellites such as ASCA, it is possible to study the energetics and evolution of the compact remnant.

  16. Current status in remnant gastric cancer after distal gastrectomy

    PubMed Central

    Ohira, Masaichi; Toyokawa, Takahiro; Sakurai, Katsunobu; Kubo, Naoshi; Tanaka, Hiroaki; Muguruma, Kazuya; Yashiro, Masakazu; Onoda, Naoyoshi; Hirakawa, Kosei

    2016-01-01

    Remnant gastric cancer (RGC) and gastric stump cancer after distal gastrectomy (DG) are recognized as the same clinical entity. In this review, the current knowledges as well as the non-settled issues of RGC are presented. Duodenogastric reflux and denervation of the gastric mucosa are considered as the two main factors responsible for the development of RGC after benign disease. On the other hand, some precancerous circumstances which already have existed at the time of initial surgery, such as atrophic gastritis and intestinal metaplasia, are the main factors associated with RGC after gastric cancer. Although eradication of Helicobacter pylori (H. pylori) in remnant stomach is promising, it is still uncertain whether it can reduce the risk of carcinogenesis. Periodic endoscopic surveillance after DG was reported useful in detecting RGC at an early stage, which offers a chance to undergo minimally invasive endoscopic treatment or laparoscopic surgery and leads to an improved prognosis in RGC patients. Future challenges may be expected to elucidate the benefit of eradication of H. pylori in the remnant stomach if it could reduce the risk for RGC, to build an optimal endoscopic surveillance strategy after DG by stratifying the risk for development of RGC, and to develop a specific staging system for RGC for the standardization of the treatment by prospecting the prognosis. PMID:26937131

  17. Gravitational waves from the remnants of the first stars

    NASA Astrophysics Data System (ADS)

    Hartwig, Tilman; Volonteri, Marta; Bromm, Volker; Klessen, Ralf S.; Barausse, Enrico; Magg, Mattis; Stacy, Athena

    2016-07-01

    Gravitational waves (GWs) provide a revolutionary tool to investigate yet unobserved astrophysical objects. Especially the first stars, which are believed to be more massive than present-day stars, might be indirectly observable via the merger of their compact remnants. We develop a self-consistent, cosmologically representative, semi-analytical model to simulate the formation of the first stars. By extrapolating binary stellar-evolution models at 10 per cent solar metallicity to metal-free stars, we track the individual systems until the coalescence of the compact remnants. We estimate the contribution of primordial stars to the merger rate density and to the detection rate of the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO). Owing to their higher masses, the remnants of primordial stars produce strong GW signals, even if their contribution in number is relatively small. We find a probability of ≳1 per cent that the current detection GW150914 is of primordial origin. We estimate that aLIGO will detect roughly 1 primordial BH-BH merger per year for the final design sensitivity, although this rate depends sensitively on the primordial initial mass function (IMF). Turning this around, the detection of black hole mergers with a total binary mass of ˜ 300 M⊙ would enable us to constrain the primordial IMF.

  18. Structure of merger remnants. II - Progenitors with rotating bulges

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars

    1993-01-01

    Mergers of identical galaxies consisting of self-gravitating disks, bulges, and halos are examined in the context of the suggestion that such events may form elliptical galaxies. Unlike earlier studies, the simulations reported here include effects arising from intrinsic spin of bulges. It is found that the disks and bulges are able to redistribute their angular momentum so that the luminous remnants rotate slowly near their centers. In addition, if the bulges are sufficiently concentrated, the core radii of the remnants are significantly reduced relative to those of end-states formed in mergers between pure stellar disks to the extent that the remnants share structural properties with observed elliptical galaxies. Nevertheless, it does appear that stellar-dynamical mergers between spiral progenitors will represent a viable mechanism for the production of massive elliptical galaxies only if sufficient mass resides already in dense, spheroidal components. These results suggest that any ellipticals formed in this manner having featureless light profiles were victims of a 'disk-bulge conspiracy' analogous to the disk-halo conspiracy thought to give rise to smooth rotation curves in spiral galaxies. Possible observational signatures of mergers are discussed, along with implications of the findings for our understanding of galaxy formation and evolution.

  19. Dynamical Evolution of Supernova Remnants Breaking Through Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Cho, Wankee; Kim, Jongsoo; Koo, Bon-Chul

    2015-04-01

    We carry out three-dimensional hydrodynamic simulations of the supernova remnants (SNRs) produced inside molecular clouds (MCs) near their surface using the HLL code tep{har83}. We explore the dynamical evolution and the X-ray morphology of SNRs after breaking through the MC surface for ranges of the explosion depths below the surface and the density ratios of the clouds to the intercloud media (ICM). We find that if an SNR breaks out through an MC surface in its Sedov stage, the outermost dense shell of the remnant is divided into several layers. The divided layers are subject to the Rayleigh-Taylor instability and fragmented. On the other hand, if an SNR breaks through an MC after the remnant enters the snowplow phase, the radiative shell is not divided to layers. We also compare the predictions of previous analytic solutions for the expansion of SNRs in stratified media with our one-dimensional simulations. Moreover, we produce synthetic X-ray surface brightness in order to research the center-bright X-ray morphology shown in thermal composite SNRs. In the late stages, a breakout SNR shows the center-bright X-ray morphology inside an MC in our results. We apply our model to the observational results of the X-ray morphology of the thermal composite SNR 3C 391.

  20. Tycho: ambient medium structure by analysis of the supernova remnant

    NASA Astrophysics Data System (ADS)

    Beshley, V.; Dubner, G.; Kuzyo, T.; Miceli, M.; Orlando, S.; Ostrowski, M.; Petruk, O.

    2016-06-01

    The radio (VLA) and X-ray (Chandra) maps of the remnant of the Tycho supernova (SN1572) are used to study the interstellar medium (ISM) density and magnetic field gradients in the ambient medium surrounding the remnant. The analysis uses also the GeV gamma-ray spectrum derived from the recent Fermi data, the radio fluxes from different radio instruments, X-ray spectrum from Suzaku and TeV gamma-ray spectrum from VERITAS. The inferred orientation of ISM density gradient is verified by comparing it to the VLA maps of interstellar medium surrounding the remnant, while the revealed orientation of the magnetic field gradient is checked by measurements of the magnetic field strength in a number of local regions around the shock. The two approaches are applied in order to estimate the magnetic field strength, involving analysis of the temporal variations of the X-ray synchrotron radiation from the shock and modeling the radial X-ray external shock profiles. As a result we reveal that the magnetic field gradient in vicinity of Tycho is almost parallel to the Galactic plane while the interstellar plasma density gradient is almost perpendicular to it. One should note that different approaches adopted in this study lead to fully compatible results.

  1. Search for Nonthermal X-Rays from Supernova Remnant Shells

    NASA Astrophysics Data System (ADS)

    Petre, R.; Keohane, J.; Hwang, U.; Allen, G.; Gotthelf, E.

    The demonstration by ASCA that the nonthermal X-ray emission from the rim of SN1006 is synchrotron emission from TeV electrons, produced in the same environment responsible for cosmic ray protons and nuclei (Koyama et al. 1995, Nature 378, 255), has stimulated a search for nonthermal X-rays from other remnants. Nonthermal emission has subsequently been found to arise in the shells of at least two other remnants, Cas A and IC 443. In Cas A, a hard tail is detected using ASCA, XTE, and OSSE to energies exceeding 100 keV; the shape of the spectrum rules out all mechanisms except synchrotron radiation. In IC 443, the previously known hard emission has been shown using ASCA to be isolated to a small region along the rim of the remnant, where the shock is interacting most strongly with a molecular cloud. Nonthermal X-ray emission is thought to arise here by enhanced cosmic ray production associated with the shock/cloud interaction (Keohane et al. 1997, ApJ in press). We describe the properties of the nonthermal emission in SN1006, Cas A, and IC 443, and discuss the status of our search for nonthermal emission associated with the shocks of other Galactic and LMC SNR's.

  2. The First Reported Infrared Emission from the SN1006 Remnant

    NASA Technical Reports Server (NTRS)

    Winkler, P. Frank; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Ghavamian, Parviz; Long, Knox S.; Raymond, John C.; Reynolds, Stephen P.

    2012-01-01

    We report results of infrared imaging and spectroscopic observations of the SN 1006 remnant, carried out with the Spitzer Space Telescope. The 24 m image from MIPS clearly shows faint filamentary emission along the northwest rim of the remnant shell, nearly coincident with the Balmer filaments that delineate the present position of the expanding shock. The 24 m emission traces the Balmer filaments almost perfectly, but lies a few arcsec within, indicating an origin in interstellar dust heated by the shock. Subsequent decline in the IR behind the shock is presumably due largely to grain destruction through sputtering. The emission drops far more rapidly than current models predict, however, even for a higher proportion of small grains than would be found closer to the Galactic plane. The rapid drop may result in part from a grain density that has always been lowera relic effect from an earlier epoch when the shock was encountering a lower densitybut higher grain destruction rates still seem to be required. Spectra from three positions along the NW filament from the IRS instrument all show only a featureless continuum, consistent with thermal emission from warm dust. The dust-to-gas mass ratio in the pre-shock interstellar medium is lower than that expected for the Galactic ISM-as has also been observed in the analysis of IR emission from other SNRs but whose cause remains unclear. As with other SNIa remnants, SN1006 shows no evidence for dust grain formation in the supernova ejecta.

  3. What do the remnants of superluminous supernovae look like?

    NASA Astrophysics Data System (ADS)

    Leloudas, G.

    2016-06-01

    The remnants of core-collapse supernovae often present significant asymmetries while those of thermonuclear supernovae are, more or less, spherically symmetric. As superluminous supernovae (SLSN) do not occur in Milky Way-type galaxies (they prefer metal-poor starburst dwarfs), our chances of studying directly a SLSN remnant are very limited, except perhaps in the Magellanic clouds. Therefore, the only way of probing the SLSN geometry, and thus identifying potential SLSN remnant candidates, is through polarimetry of the explosions themselves. I will present the first polarimetric observations of SLSNe obtained through a dedicated ToO program at the VLT. LSQ14mo is a SLSN-I that showed only a very limited degree of polarisation (P = 0.52%), which corresponds to an upper limit of 10% in the photosphere asphericity. In addition, this signal can be entirely due to interstellar polarisation in the host galaxy. This is perhaps surprising as the leading models for H-poor SLSNe involve a magnetar or CSM interaction, i.e. configurations that are not expected to be spherically symmetric. Observations of a SLSN-II yielded a more significant degree of polarisation, while preliminary analysis for a SLSN-R reveals similarly low levels of asphericity as for LSQ14mo.

  4. A comparison of remnants in noncommutative Bardeen black holes

    NASA Astrophysics Data System (ADS)

    Mehdipour, S. Hamid; Ahmadi, M. H.

    2016-09-01

    We derive the mass term of the Bardeen metric in the presence of a noncommutative geometry induced minimal length. In this setup, the proposal of a stable black hole remnant as a candidate to store information is confirmed. We consider the possibility of having an extremal configuration with one degenerate event horizon and compare different sizes of black hole remnants. As a result, once the magnetic charge g of the noncommutative Bardeen solution becomes larger, both the minimal nonzero mass M0 and the minimal nonzero horizon radius r0 get larger. This means, subsequently, under the condition of an adequate amount of g, the three parameters g, M0, and r0 are in a connection with each other linearly. According to our results, a noncommutative Bardeen black hole is colder than the noncommutative Schwarzschild black hole and its remnant is bigger, so the minimum required energy for the formation of such a black hole at particle colliders will be larger. We also find a closely similar result for the Hayward solution.

  5. Are young supernova remnants interacting with circumstellar gas

    SciTech Connect

    Chevalier, R.A.

    1982-08-15

    The young remnants of galactic Type I supernovae (SN 1006, SN 1572, and SN 1604) appear to be interacting with moderately dense gas (n/sub O/> or =0.1 cm/sup -3/). If the gas in the ambient interstellar medium, the observations suggest that gas of this density is fairly pervasive. If the gas is circumstellar, there are important implications for the progenitors of Type I supernovae. A plausible density distribution for circumstellar gas is rhoinfinityr/sup -2/. The expansion of a supernova into such a medium is examined and is compared with expansion into a uniform medium. The two cases can be distinguished on the basis of their density profiles and their rates of expansion. Currently available data factor the hypothesis of expansion in a uniform medium for all three Type I remnants; the evidence is the strongest for SN 1572 and the weakest for SN 1604. Further X-ray and radio observations of the galactic remnants and of extragalactic Type I supernovae should serve to test this hypothesis.

  6. What We Can Learn From Supernova Remnant Size Distributions

    NASA Astrophysics Data System (ADS)

    Elwood, Benjamin; Murphy, Jeremiah; Diaz, Mariangelly

    2016-01-01

    Previous literature regarding size distributions of supernova remnants generally discuss a uniform distribution for the radius, occasionally considering a Gaussian alternative. We indeed show that these distributions are consistent with log-normal, which can be considered a natural consequence of the Central Limit Theorem and Sedov expansion. Modeling explosion energy, remnant age, and ambient density as independent, random distributions, we show, using simple Monte Carlo simulations, that the size distribution is indistinguishable from log-normal when the SNR sample size is of order three hundred. This implies that these SNR distributions provide only information on the mean and variance, yielding additional information only when the sample size grows large. We then proceed to Bayesian statistical inference to characterize the information provided by the size distributions. In particular, we use the mean and variance of sizes and explosion energies to subsequently estimate the mean and variance of the ambient medium surrounding SNR progenitors. This in turn allows us to characterize potential bias in studies involving samples of supernova remnants.

  7. Fire-Retardant Epoxy Adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.

    1982-01-01

    Phosphorus-containing epoxy is fire-retardant and translucent. Intended as adhesive for laminated plastic sheets, new material bonds well to titanium dioxide-filled plastic film, which ordinarily shows little surface interaction with adhesives. Fire retardancy has been demonstrated, and smoke density is low enough to avoid smoke obscuration.

  8. Platelet adhesiveness in diabetes mellitus

    PubMed Central

    Shaw, S.; Pegrum, G. D.; Wolff, Sylvia; Ashton, W. L.

    1967-01-01

    Platelet adhesiveness has been assessed on whole blood from a series of 34 diabetics and 50 control subjects using adenosine diphosphate (A.D.P.) and by adherence to glass microspherules (ballotini). Using both techniques it was possible to demonstrate a significant increase in platelet adhesiveness in the diabetic patients. PMID:5614070

  9. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  10. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  11. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  12. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  13. Epidural Lysis of Adhesions

    PubMed Central

    Lee, Frank; Jamison, David E.; Hurley, Robert W.

    2014-01-01

    As our population ages and the rate of spine surgery continues to rise, the use epidural lysis of adhesions (LOA) has emerged as a popular treatment to treat spinal stenosis and failed back surgery syndrome. There is moderate evidence that percutaneous LOA is more effective than conventional ESI for both failed back surgery syndrome, spinal stenosis, and lumbar radiculopathy. For cervical HNP, cervical stenosis and mechanical pain not associated with nerve root involvement, the evidence is anecdotal. The benefits of LOA stem from a combination of factors to include the high volumes administered and the use of hypertonic saline. Hyaluronidase has been shown in most, but not all studies to improve treatment outcomes. Although infrequent, complications are more likely to occur after epidural LOA than after conventional epidural steroid injections. PMID:24478895

  14. Adhesion testing device

    NASA Technical Reports Server (NTRS)

    LaPeyronnie, Glenn M. (Inventor); Huff, Charles M. (Inventor)

    2010-01-01

    The present invention provides a testing apparatus and method for testing the adhesion of a coating to a surface. The invention also includes an improved testing button or dolly for use with the testing apparatus and a self aligning button hook or dolly interface on the testing apparatus. According to preferred forms, the apparatus and method of the present invention are simple, portable, battery operated rugged, and inexpensive to manufacture and use, are readily adaptable to a wide variety of uses, and provide effective and accurate testing results. The device includes a linear actuator driven by an electric motor coupled to the actuator through a gearbox and a rotatable shaft. The electronics for the device are contained in the head section of the device. At the contact end of the device, is positioned a self aligning button hook, attached below the load cell located on the actuator shaft.

  15. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, R.A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe with an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough. 4 figs.

  16. Biological adhesives and fastening devices

    NASA Astrophysics Data System (ADS)

    Wolpert, H. D.

    2012-04-01

    Sea creatures are a leading source to some of the more interesting discoveries in adhesives. Because sea water naturally breaks down even the strongest conventional adhesive, an alternative is important that could be used in repairing or fabricating anything that might have regular contact with moisture such as: Repairing broken and shattered bones, developing a surgical adhesive, use in the dental work, repairing and building ships, and manufacturing plywood. Some of nature's prototypes include the common mussel, limpet, some bacteria and abalone. As we learn more about these adhesives we are also developing non adhesive fasteners, such as mimicked after studying the octopus, burdock burrs (i.e. Velcro®) and the gecko.

  17. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, Ray A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe within an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough.

  18. Dance into the fire: dust survival inside supernova remnants

    NASA Astrophysics Data System (ADS)

    Micelotta, Elisabetta R.; Dwek, Eli; Slavin, Jonathan D.

    2016-06-01

    Core collapse supernovae (CCSNe) are important sources of interstellar dust, potentially capable of producing 1 M_{⊙}) of dust in their explosively expelled ejecta. However, unlike other dust sources, the dust has to survive the passage of the reverse shock, generated by the interaction of the supernova blast wave with its surrounding medium. Knowledge of the net amount of dust produced by CCSNe is crucial for understanding the origin and evolution of dust in the local and high-redshift universe. Our goal is to identify the dust destruction mechanisms in the ejecta, and derive the net amount of dust that survives the passage of the reverse shock. To do so, we have developed analytical models for the evolution of a supernova blast wave and of the reverse shock, and the simultaneous processing of the dust inside the cavity of the supernova remnant. We have applied our models to the special case of the clumpy ejecta of the remnant of Cassiopeia A (Cas A), assuming that the dust (silicates and carbon grains) resides in cool oxygen-rich ejecta clumps which are uniformly distributed within the remnant and surrounded by a hot X-ray emitting plasma (smooth ejecta). The passage of the reverse shock through the clumps gives rise to a relative gas-grain motion and also destroys the clumps. While residing in the ejecta clouds, dust is processed via kinetic sputtering, which is terminated either when the grains escape the clumps, or when the clumps are destroyed by the reverse shock. In either case, grain destruction proceeds thereafter by thermal sputtering in the hot shocked smooth ejecta. We find that 12 and 16 percent of silicate and carbon dust, respectively, survive the passage of the reverse shock by the time the shock has reached the center of the remnant. These fractions depend on the morphology of the ejecta and the medium into which the remnant is expanding, as well as the composition and size distribution of the grains that formed in the ejecta. Results will

  19. Forward Shock Proper Motions of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Katsuda, S.; Tsunemi, H.; Uchida, H.; Kimura, M.

    2008-12-01

    The X-ray structure of Kepler's supernova remnant shows a rounded shape delineated by forward shocks. We measure proper motions of the forward shocks on overall rims of the remnant, by using archival Chandra data taken in two epochs with time difference of 6.09 yr. The proper motions of the forward shocks on the northern rim are measured to be 0.076'' (±0.032'' ±0.016'') to 0.11'' (±0.014'' ±0.016'') yr-1, while those on the rest of the rims are measured to be 0.15'' (±0.017'' ±0.016'') to 0.30'' (±0.048'' ±0.016'') yr-1 here the first-term errors are statistical uncertainties and the second-term errors are systematic uncertainties. Combining the best-estimated shock velocity of 1660 +/- 120 km s-1 measured for Balmer-dominated filaments in the northern and central portions of the remnant (Sankrit et al. 2005) with the proper motions derived for the forward shocks on the northern rim, we estimate a distance of 3.3+1.6-0.4 kpc to the remnant. We measure the expansion indices, m (defined as R propto tm), to be 0.47-0.82 for most of the rims. These values are consistent with those expected in Type Ia SN explosion models, in which the ejecta and the circumstellar medium have power-law density profiles whose indices are 5-7 and 0-2, respectively. In addition, we should note the slower expansion on the northern rim than that on the southern rim. This is likely caused by the inhomogeneous circumstellar medium; the density of the circumstellar medium is higher in the north than that in the south of the remnant. The newly estimated geometric center, around which we believe the explosion point exists, is located at ~5'' offset to the north of the radio center.

  20. EVOLUTION OF POST-IMPACT REMNANT HELIUM STARS IN TYPE Ia SUPERNOVA REMNANTS WITHIN THE SINGLE-DEGENERATE SCENARIO

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu

    2013-08-10

    The progenitor systems of Type Ia supernovae (SNe Ia) are still under debate. Based on recent hydrodynamics simulations, non-degenerate companions in the single-degenerate scenario (SDS) should survive the supernova (SN) impact. One way to distinguish between the SDS and the double-degenerate scenario is to search for the post-impact remnant stars (PIRSs) in SN Ia remnants. Using a technique that combines multi-dimensional hydrodynamics simulations with one-dimensional stellar evolution simulations, we have examined the post-impact evolution of helium-rich binary companions in the SDS. It is found that these helium-rich PIRSs (He PIRSs) dramatically expand and evolve to a luminous phase (L {approx} 10{sup 4} L{sub Sun }) about 10 yr after an SN explosion. Subsequently, they contract and evolve to become hot blue-subdwarf-like (sdO-like) stars by releasing gravitational energy, persisting as sdO-like stars for several million years before evolving to the helium red-giant phase. We therefore predict that a luminous OB-like star should be detectable within {approx}30 yr after the SN explosion. Thereafter, it will shrink and become an sdO-like star in the central regions of SN Ia remnants within star-forming regions for SN Ia progenitors evolved via the helium-star channel in the SDS. These He PIRSs are predicted to be rapidly rotating (v{sub rot} {approx}> 50 km s{sup -1}) and to have high spatial velocities (v{sub linear} {approx}> 500 km s{sup -1}). Furthermore, if SN remnants have diffused away and are not recognizable at a later stage, He PIRSs could be an additional source of single sdO stars and/or hypervelocity stars.

  1. Nonthermal emission properties of the northwestern rim of supernova remnant RX J0852.0-4622

    NASA Astrophysics Data System (ADS)

    Kishishita, T.; Hiraga, J.; Uchiyama, Y.

    2013-03-01

    The supernova remnant (SNR) RX J0852.0-4622 (Vela Jr., G266.6-1.2) is one of the most important SNRs for investigating the acceleration of multi-TeV particles and the origin of Galactic cosmic rays because of its strong synchrotron X-ray and TeV γ-ray emission, which show a shell-like morphology similar to each other. Using the XMM-Newton archival data consisting of multiple pointing observations of the northwestern rim of the remnant, we investigate the spatial properties of the nonthermal X-ray emission as a function of distance from an outer shock wave. All X-ray spectra are well reproduced by an absorbed power-law model above 2 keV. It is found that the spectra show gradual softening from a photon index Γ = 2.56 in the rim region to Γ = 2.96 in the interior region. We show that this radial profile can be interpreted as a gradual decrease of the cutoff energy of the electron spectrum due to synchrotron cooling. By using a simple spectral evolution model that includes continuous synchrotron losses, the spectral softening can be reproduced with the magnetic field strength in the post-shock flow to less than several tens of μG. If this is a typical magnetic field in the SNR shell, γ-ray emission would be accounted for by inverse Compton scattering of high-energy electrons that also produce the synchrotron X-ray emission. Future hard X-ray imaging observations with Nustar and ASTRO-H and TeV γ-ray observations with the Cherenkov Telescope Array (CTA) will allow us to explore other possible explanations of the systematic softening of the X-ray spectra.

  2. Neutrophil adhesion in leukocyte adhesion deficiency syndrome type 2.

    PubMed Central

    Phillips, M L; Schwartz, B R; Etzioni, A; Bayer, R; Ochs, H D; Paulson, J C; Harlan, J M

    1995-01-01

    We have previously reported a newly discovered congenital disorder of neutrophil adhesion, leukocyte adhesion deficiency syndrome type 2 (LAD II). The clinical manifestations of this syndrome are similar to those seen in the classic leukocyte adhesion deficiency syndrome, now designated type 1 (LAD I), but the two syndromes differ in the molecular basis of their adhesion defects. LAD I is caused by a deficiency in the CD18 integrin adhesion molecules while LAD II patients are deficient in expression of sialyl-Lewis X (SLeX), a carbohydrate ligand for selectins. In this report we demonstrate that neutrophils from a LAD II patient bind minimally or not at all to recombinant E-selectin, purified platelet P-selectin, or P-selectin expressed on histamine-activated human umbilical vein endothelial cells, but have normal levels of L-selectin and CD11b/CD18 integrin, and adhere to and migrate across endothelium when CD11b/CD18 is activated. We compare LAD I and LAD II patient neutrophil function in vitro, demonstrating that integrin and selectin adhesion molecules have distinct but interdependent roles in neutrophil adhesion during an inflammatory response. Images PMID:8675661

  3. Effect of Atmospheric Pressure Plasma Treatment on Surface Characteristics and Adhesive Bond Quality of Peel Ply Prepared Composites

    NASA Astrophysics Data System (ADS)

    Tracey, Ashley C.

    The purpose of this research was to investigate if atmospheric pressure plasma treatment could modify peel ply prepared composite surfaces to create strong adhesive bonds. Two peel ply surface preparation composite systems previously shown to create weak bonds (low fracture energy and adhesion failure) that were potential candidates for plasma treatment were Toray T800/3900-2 carbon fiber reinforced polymer (CFRP) prepared with Precision Fabrics Group, Inc. (PFG) 52006 nylon peel ply and Hexcel T300/F155 CFRP prepared with PFG 60001 polyester peel ply. It was hypothesized that atmospheric pressure plasma treatment could functionalize and/or remove peel ply remnants left on the CFRP surfaces upon peel ply removal. Surface characterization measurements and double cantilever beam (DCB) testing were used to determine the effects of atmospheric pressure plasma treatment on surface characteristics and bond quality of peel ply prepared CFRP composites. Previous research showed that Toray T800/3900-2 carbon fiber reinforced epoxy composites prepared with PFG 52006 peel ply and bonded with Cytec MetlBond 1515-3M structural film adhesive failed in adhesion at low fracture energies when tested in the DCB configuration. Previous research also showed that DCB samples made of Hexcel T300/F155 carbon fiber reinforced epoxy composites prepared with PFG 60001 peel ply and bonded with Henkel Hysol EA 9696 structural film adhesive failed in adhesion at low fracture energies. Recent research suggested that plasma treatment could be able to activate these "un-bondable" surfaces and result in good adhesive bonds. Nylon peel ply prepared 177 °C cure and polyester peel ply prepared 127 °C cure CFRP laminates were treated with atmospheric pressure plasma after peel ply removal prior to bonding. Atmospheric pressure plasma treatment was capable of significantly increasing fracture energies and changing failure modes. For Toray T800/3900-2 laminates prepared with PFG 52006 and bonded with

  4. Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives.

    PubMed

    Murphy, Michael P; Kim, Seok; Sitti, Metin

    2009-04-01

    The complex structures that allow geckos to repeatably adhere to surfaces consist of multilevel branching fibers with specialized tips. We present a novel technique for fabricating similar multilevel structures from polymer materials and demonstrate the fabrication of arrays of two- and three-level structures, wherein each level terminates in flat mushroom-type tips. Adhesion experiments are conducted on two-level fiber arrays on a 12-mm-diameter glass hemisphere, which exhibit both increased adhesion and interface toughness over one-level fiber samples and unstructured control samples. These adhesion enhancements are the result of increased surface conformation as well as increased extension during detachment.

  5. Wet Adhesion and Adhesive Locomotion of Snails on Anti-Adhesive Non-Wetting Surfaces

    PubMed Central

    Shirtcliffe, Neil J.; McHale, Glen; Newton, Michael I.

    2012-01-01

    Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces. PMID:22693563

  6. Adhesive friction based on finite element study and n-point asperity model

    NASA Astrophysics Data System (ADS)

    Sahoo, Prasanta; Waghmare, Ajay K.

    2016-08-01

    The present work considers analysis of adhesive friction of rough surfaces using n- point asperity concept for statistical definition of surface roughness features, and accurate finite element analysis of elastic-plastic deformation of single asperity contact. Well defined adhesion index and plasticity index are used to study the prospective contact situations arising out of variation in material properties and surface roughness features. From the present results it is possible to locate the combinations of adhesion index and plasticity index that may yield very low coefficient of friction. Thus suitable choice of surface and material parameters for the contact of two rough surfaces can be made in order to minimize friction typically at low load and micro scale roughness situations.

  7. Marine Bioinspired Underwater Contact Adhesion.

    PubMed

    Clancy, Sean K; Sodano, Antonio; Cunningham, Dylan J; Huang, Sharon S; Zalicki, Piotr J; Shin, Seunghan; Ahn, B Kollbe

    2016-05-01

    Marine mussels and barnacles are sessile biofouling organisms that adhere to a number of surfaces in wet environments and maintain remarkably strong bonds. Previous synthetic approaches to mimic biological wet adhesive properties have focused mainly on the catechol moiety, present in mussel foot proteins (mfps), and especially rich in the interfacial mfps, for example, mfp-3 and -5, found at the interface between the mussel plaque and substrate. Barnacles, however, do not use Dopa for their wet adhesion, but are instead rich in noncatecholic aromatic residues. Due to this anomaly, we were intrigued to study the initial contact adhesion properties of copolymerized acrylate films containing the key functionalities of barnacle cement proteins and interfacial mfps, for example, aromatic (catecholic or noncatecholic), cationic, anionic, and nonpolar residues. The initial wet contact adhesion of the copolymers was measured using a probe tack testing apparatus with a flat-punch contact geometry. The wet contact adhesion of an optimized, bioinspired copolymer film was ∼15.0 N/cm(2) in deionized water and ∼9.0 N/cm(2) in artificial seawater, up to 150 times greater than commercial pressure-sensitive adhesive (PSA) tapes (∼0.1 N/cm(2)). Furthermore, maximum wet contact adhesion was obtained at ∼pH 7, suggesting viability for biomedical applications. PMID:27046671

  8. Osteoblast adhesion on nanophase ceramics.

    PubMed

    Webster, T J; Siegel, R W; Bizios, R

    1999-07-01

    Osteoblast adhesion on nanophase alumina (Al2O3) and titania (TiO2) was investigated in vitro. Osteoblast adhesion to nanophase alumina and titania in the absence of serum from Dulbecco's modified Eagle medium (DMEM) was significantly (P < 0.01) less than osteoblast adhesion to alumina and titania in the presence of serum. In the presence of 10% fetal bovine serum in DMEM osteoblast adhesion on nanophase alumina (23 nm grain size) and titania (32 nm grain size) was significantly (P < 0.05) greater than on conventional alumina (177 nm grain size) and titania (2.12 microm grain size), respectively, after 1, 2, and 4 h. Further investigation of the dependence of osteoblast adhesion on alumina and titania grain size indicated the presence of a critical grain size for osteoblast adhesion between 49 and 67 nm for alumina and 32 and 56 nm for titania. The present study provides evidence of the ability of nanophase alumina and titania to simulate material characteristics (such as surface grain size) of physiological bone that enhance protein interactions (such as adsorption, configuration, bioactivity, etc.) and subsequent osteoblast adhesion.

  9. Adhesives from modified soy protein

    DOEpatents

    Sun, Susan; Wang, Donghai; Zhong, Zhikai; Yang, Guang

    2008-08-26

    The, present invention provides useful adhesive compositions having similar adhesive properties to conventional UF and PPF resins. The compositions generally include a protein portion and modifying ingredient portion selected from the group consisting of carboxyl-containing compounds, aldehyde-containing compounds, epoxy group-containing compounds, and mixtures thereof. The composition is preferably prepared at a pH level at or near the isoelectric point of the protein. In other preferred forms, the adhesive composition includes a protein portion and a carboxyl-containing group portion.

  10. Foreign material in postoperative adhesions.

    PubMed Central

    Luijendijk, R W; de Lange, D C; Wauters, C C; Hop, W C; Duron, J J; Pailler, J L; Camprodon, B R; Holmdahl, L; van Geldorp, H J; Jeekel, J

    1996-01-01

    OBJECTIVE: The authors determined the prevalence of foreign body granulomas in intra-abdominal adhesions in patients with a history of abdominal surgery. PATIENTS AND METHODS: In a cross-sectional, multicenter, multinational study, adult patients with a history of one or more previous abdominal operations and scheduled for laparotomy between 1991 and 1993 were examined during surgery. Patients in whom adhesions were present were selected for study. Quantity, distribution, and quality of adhesions were scored, and adhesion samples were taken for histologic examination. RESULTS: In 448 studied patients, the adhesions were most frequently attached to the omentum (68%) and the small bowel (67%). The amount of adhesions was significantly smaller in patients with a history of only one minor operation or one major operation, compared with those with multiple laparotomies (p < 0.001). Significantly more adhesions were found in patients with a history of adhesions at previous laparotomy (p < 0.001), with presence of abdominal abscess, hematoma, and intestinal leakage as complications after former surgery (p = 0.01, p = 0.002, and p < 0.001, respectively), and with a history of an unoperated inflammatory process (p = 0.04). Granulomas were found in 26% of all patients. Suture granulomas were found in 25% of the patients. Starch granulomas were present in 5% of the operated patients whose surgeons wore starch-containing gloves. When suture granulomas were present, the median interval between the present and the most recent previous laparotomy was 13 months. When suture granulomas were absent, this interval was significantly longer--i.e., 30 months (p = 0.002). The percentage of patients with suture granulomas decreased gradually from 37% if the previous laparotomy had occurred up to 6 months before the present operation, to 18% if the previous laparotomy had occurred more than 2 years ago (p < 0.001). CONCLUSIONS: The number of adhesions found at laparotomy was significantly

  11. Interfacial adhesion of carbon fibers

    NASA Technical Reports Server (NTRS)

    Bascom, Willard D.

    1987-01-01

    Relative adhesion strengths between AS4, AS1, and XAS carbon fibers and thermoplastic polymers were determined using the embedded single filament test. Polymers studied included polycarbonate, polyphenylene oxide, polyetherimide, polysulfone, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate polysiloxane block copolymer. Fiber surface treatments and sizings improved adhesion somewhat, but adhesion remained well below levels obtained with epoxy matrices. An explanation for the differences between the Hercules and Grafil fibers was sought using X ray photon spectroscopy, wetting, scanning electron microscopy and thermal desorption analysis.

  12. Notch-Mediated Cell Adhesion

    PubMed Central

    Murata, Akihiko; Hayashi, Shin-Ichi

    2016-01-01

    Notch family members are generally recognized as signaling molecules that control various cellular responses in metazoan organisms. Early fly studies and our mammalian studies demonstrated that Notch family members are also cell adhesion molecules; however, information on the physiological roles of this function and its origin is limited. In this review, we discuss the potential present and ancestral roles of Notch-mediated cell adhesion in order to explore its origin and the initial roles of Notch family members dating back to metazoan evolution. We hypothesize that Notch family members may have initially emerged as cell adhesion molecules in order to mediate multicellularity in the last common ancestor of metazoan organisms. PMID:26784245

  13. Photovoltaic module with adhesion promoter

    DOEpatents

    Xavier, Grace

    2013-10-08

    Photovoltaic modules with adhesion promoters and methods for fabricating photovoltaic modules with adhesion promoters are described. A photovoltaic module includes a solar cell including a first surface and a second surface, the second surface including a plurality of interspaced back-side contacts. A first glass layer is coupled to the first surface by a first encapsulating layer. A second glass layer is coupled to the second surface by a second encapsulating layer. At least a portion of the second encapsulating layer is bonded directly to the plurality of interspaced back-side contacts by an adhesion promoter.

  14. Advances in light curing adhesives

    NASA Astrophysics Data System (ADS)

    Bachmann, Andy

    2001-11-01

    This paper describes the development of a new family of light curing adhesives containing a new reactive additive previously not used in optical grade light curing adhesives are obtained with the addition of functionalized cellulositics. Outgassing as low as 10-6 grams/gram has been observed based on headspace sampling. Other additives have lowered the shrinkage rates of positioning adhesives from near 1 percent to less than 0.1 percent with fractional, percentage movements over thermal range of -40 degrees C to +200 degrees C.

  15. Wear mechanism based on adhesion

    NASA Technical Reports Server (NTRS)

    Yamamoto, T.; Buckley, D. H.

    1982-01-01

    Various concepts concerning wear mechanisms and deformation behavior observed in the sliding wear track are surveyed. The mechanisms for wear fragment formation is discussed on the basis of adhesion. The wear process under unlubricated sliding conditions is explained in relation to the concept of adhesion at the interface during the sliding process. The mechanism for tearing away the surface layer from the contact area and forming the sliding track contour is explained by assuming the simplified process of material removal based on the adhesion theory.

  16. OXYGEN-RICH SUPERNOVA REMNANT IN THE LARGE MAGELLANIC CLOUD

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is a NASA Hubble Space Telescope image of the tattered debris of a star that exploded 3,000 years ago as a supernova. This supernova remnant, called N132D, lies 169,000 light-years away in the satellite galaxy, the Large Magellanic Cloud. A Hubble Wide Field Planetary Camera 2 image of the inner regions of the supernova remnant shows the complex collisions that take place as fast moving ejecta slam into cool, dense interstellar clouds. This level of detail in the expanding filaments could only be seen previously in much closer supernova remnants. Now, Hubble's capabilities extend the detailed study of supernovae out to the distance of a neighboring galaxy. Material thrown out from the interior of the exploded star at velocities of more than four million miles per hour (2,000 kilometers per second) plows into neighboring clouds to create luminescent shock fronts. The blue-green filaments in the image correspond to oxygen-rich gas ejected from the core of the star. The oxygen-rich filaments glow as they pass through a network of shock fronts reflected off dense interstellar clouds that surrounded the exploded star. These dense clouds, which appear as reddish filaments, also glow as the shock wave from the supernova crushes and heats the clouds. Supernova remnants provide a rare opportunity to observe directly the interiors of stars far more massive than our Sun. The precursor star to this remnant, which was located slightly below and left of center in the image, is estimated to have been 25 times the mass of our Sun. These stars 'cook' heavier elements through nuclear fusion, including oxygen, nitrogen, carbon, iron etc., and the titanic supernova explosions scatter this material back into space where it is used to create new generations of stars. This is the mechanism by which the gas and dust that formed our solar system became enriched with the elements that sustain life on this planet. Hubble spectroscopic observations will be used to determine the exact

  17. Remnant radio galaxies in the LOFAR Lockman Hole

    NASA Astrophysics Data System (ADS)

    Brienza, Marisa; Godfrey, Leith; Morganti, Raffaella

    2016-08-01

    I will present recent 150-MHz deep observations performed with the Low-frequency Array (LOFAR) of the well-known extragalactic region of the Lockman Hole. Thanks to its high sensitivity and resolution this data allows us to perform new studies of the radio loud AGN population at low radio frequencies. In particular, we conducted a systematic search of remnant radio galaxies, which represent the final "dying" phase of the radio galaxy evolution, when the jets have switched off. This class of sources is best to investigate the life-cycle of radio loud AGN as well as to quantify the role of radio AGN feedback. Indeed, the modelling of their radio spectrum provides constraints on the time-scales of activity and quiescence of the radio source and on its energy output. For a long time there have been claims that deep low-frequency surveys would have enhanced the detection of this class of sources, which are usually rare in flux limited samples.With our search, we thus intend to provide good statistics on the detection and properties of remnant radio galaxies. To avoid selection biases towards any specific class of objects we used both morphological and spectral selection criteria. To do this we combined the LOFAR data with publicly available surveys at other frequencies as well as dedicated deep observations. We find that the fraction of candidate remnant sources is < 6-8% of the entire radio source population and is dominated by steep spectrum sources. To better understand the observed fraction we developed mock catalogues of the radio sky population based on radio galaxy evolution models. These models are used to constrain the main mechanisms contributing to the source luminosity evolution i.e. adiabatic expansion, radiative losses, as well as to make predictions on their fraction in flux limited samples.

  18. High or low dose radioiodine ablation of thyroid remnants?

    PubMed

    Creutzig, H

    1987-01-01

    The need for high dose radioiodine for ablation of remnants in patients with thyroid cancer is still in question. We compared the effectiveness of high and low dose 131I for ablation in patients in a prospective randomized study after surgical thyroidectomy. Twenty patients with differentiated pT2-3NoMo thyroid cancer were studied. The uptake was 5%-10% at 24 h. Ten patients received 100 mCi, the others 30 mCi 131I. Three months later all patients received a therapeutic dose of 150 mCi 131I. Another twenty patients with known distant metastases (pulmonary and/or bone) of differentiated thyroid cancer were studied. The remnant uptake was between 4%-10%. Ten patients received 300 mCi and ten 30 mCi 131I as ablation dose. Three months later all received 300 mCi 131I. The uptake at day seven was calculated for the same metastases from a whole body scan after both treatments. If effective ablation was defined as 24 h uptake in the remnant of less than 1%, then the ablation was effective in eight out of ten of the high dose and in seven out of ten of the low dose group. In pT2-3, N X M1 patients the ablation was effective in seven out of ten cases in both groups. If "effective" ablation was defined as an uptake of less than 0.5%, then the ablation was effective both in NoMo and in N X M1 patients in five out of ten with low dose and in six out of ten with high dose ablation treatment.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3569338

  19. ROSAT HRI observations of Magellanic Cloud supernova remnants

    NASA Technical Reports Server (NTRS)

    Hughes, John P.

    1994-01-01

    Analysis of deep ROSAT high resolution imager (HRI) observations of two oxygen-rich supernova remnants (SNR's) in the Magellanic Clouds is described. For N132D, I exploit the limited spectral information provided by the HRI to investigate arcsecond scale spectral variations. I find that there is a region of harder X-ray emission near the southern limb and regions of softer emission near the center and northwestern limb. The remnant is believed to be interacting with a molecular cloud and the harder emission to the south is explained as a result of increased absorption along the line-of-sight there. I argue that the softer emission comes from X-ray emitting material with an enhanced abundance of oxygen. For the second SNR, E0102.2 72.2, the spatial structure is investigated in detail using two-dimensional image fitting techniques. Evidence is found for a ring-like and a spherically symmetric shell-like component both of which were modeled as homogeneous regions. In addition, a significant fraction of the observed flux (approximately 11 percent) must come from a resolved clumped component. A comparison with optical and radio imagery is made to provide a physical basis for the components identified in the X-ray analysis. The mass of X-ray emitting gas in the remnant is estimated and a value of approximately 75 M(solar mass) was determined. The dominant uncertainty on this quantity is the extent of unresolved clumping in the X-ray gas. Such clumping would tend to reduce the mass estimate by f(exp 1/2), where f is the mean volume filling factor of the gas.

  20. Reversing Adhesion: A Triggered Release Self‐Reporting Adhesive

    PubMed Central

    Schenzel, Alexander M.; Klein, Christopher; Rist, Kai; Moszner, Norbert

    2016-01-01

    Here, the development of an adhesive is reported – generated via free radical polymerization – which can be degraded upon thermal impact within minutes. The degradation is based on a stimuli responsive moiety (SRM) that is incorporated into the network. The selected SRM is a hetero Diels‐Alder (HDA) moiety that features three key properties. First, the adhesive can be degraded at relatively low temperatures (≈80 °C), second the degradation occurs very rapidly (less than 3 min), and third, the degradation of the network can readily be analyzed and quantified due to its self‐reporting nature. The new reversible self‐reporting adhesion system is characterized in detail starting from molecular studies of the retro HDA reaction. Moreover, the mechanical properties of the network, as well as the adhesion forces, are investigated in detail and compared to common methacrylate‐based systems, demonstrating a significant decrease in mechanic stability at elevated temperatures. The current study thus represents a significant advance of the current state of the art for debonding on demand adhesives, making the system interesting for several fields of application including dental adhesives. PMID:27812461

  1. Multi-frequency observations of SNR J0453-6829 in the LMC. A composite supernova remnant with a pulsar wind nebula

    NASA Astrophysics Data System (ADS)

    Haberl, F.; Filipović, M. D.; Bozzetto, L. M.; Crawford, E. J.; Points, S. D.; Pietsch, W.; De Horta, A. Y.; Tothill, N.; Payne, J. L.; Sasaki, M.

    2012-07-01

    Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be investigated in detail with radio, optical, and X-ray observations. SNR J0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies. Aims: We study the emission of SNR J0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant. Methods: We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNR J0453-6829. We studied the morphology of SNR J0453-6829 from radio, optical, and X-ray images and investigated the energy spectra in the different parts of the remnant. Results: Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index αCore of -0.04 ± 0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with αShell = -0.43 ± 0.01. We detect regions with a mean polarisation of P ≅ (12 ± 4)% at 6 cm and (9 ± 2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31 ± 1) pc × (29 ± 1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12 000-15 000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56 cm-3, typical for LMC remnants, a large swept-up mass of 830 M⊙, and an explosion energy of 7.6 × 1050 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material.

  2. Adhesion in vascular biology

    PubMed Central

    de Rooij, Johan

    2014-01-01

    The vasculature delivers vital support for all other tissues by supplying oxygen and nutrients for growth and by transporting the immune cells that protect and cure them. Therefore, the microvasculature developed a special barrier that is permissive for gasses like oxygen and carbon dioxide, while fluids are kept inside and pathogens are kept out. While maintaining this tight barrier, the vascular wall also allows immune cells to exit at sites of inflammation or damage, a process that is called transmigration. The endothelial cell layer that forms the inner lining of the vasculature is crucial for the vascular barrier function as well as the regulation of transmigration. Therefore, adhesions between vascular endothelial cells are both tight and dynamic and the mechanisms by which they are established, and the mechanisms by which they are controlled have been extensively studied over the past decades. Because of our fundamental strive to understand biology, but also because defects in vascular barrier control cause a variety of clinical problems and treatment strategies may evolve from our detailed understanding of its mechanisms. This special focus issue features a collection of articles that review key components of the development and control of the endothelial cell-cell junction that is central to endothelial barrier function. PMID:25422845

  3. Pulsar-like emission from the supernova remnant CTB 80

    SciTech Connect

    Strom, R.G.

    1987-08-01

    A compact radio source has been found immersed in the flat-spectrum central component of the peculiar supernova remnant CTB 80. The object's apparent steep radio spectrum, moderate degree of polarization, and near-coincidence with an unresolved X-ray source are consistent with a pulsar/neutron star which provides energy to power the flat-spectrum component. Its eccentric location and other evidence suggest a fast-moving object interacting with its environment. The morphology of the surrounding emission which resembles a wisp near the center of the Crab Nebula provides clues to particle acceleration near the neutron star. 30 references.

  4. AZIMUTHAL DENSITY VARIATIONS AROUND THE RIM OF TYCHO's SUPERNOVA REMNANT

    SciTech Connect

    Williams, Brian J.; Hewitt, John W.; Petre, Robert; Borkowski, Kazimierz J.; Alwin Mao, S.; Reynolds, Stephen P.; Blondin, John M.; Ghavamian, Parviz

    2013-06-20

    Spitzer images of Tycho's supernova remnant in the mid-infrared reveal limb-brightened emission from the entire periphery of the shell and faint filamentary structures in the interior. As with other young remnants, this emission is produced by dust grains, warmed to {approx}100 K in the post-shock environment by collisions with energetic electrons and ions. The ratio of the 70 to 24 {mu}m fluxes is a diagnostic of the dust temperature, which in turn is a sensitive function of the plasma density. We find significant variations in the 70/24 flux ratio around the periphery of Tycho's forward shock, implying order-of-magnitude variations in density. While some of these are likely localized interactions with dense clumps of the interstellar medium (ISM), we find an overall gradient in the ambient density surrounding Tycho, with densities 3-10 times higher in the northeast than in the southwest. This large density gradient is qualitatively consistent with the variations in the proper motion of the shock observed in radio and X-ray studies. Overall, the mean ISM density around Tycho is quite low ({approx}0.1-0.2 cm{sup -3}), consistent with the lack of thermal X-ray emission observed at the forward shock. We perform two-dimensional hydrodynamic simulations of a Type Ia supernova expanding into a density gradient in the ISM, and find that the overall round shape of the remnant is still easily achievable, even for explosions into significant gradients. However, this leads to an offset of the center of the explosion from the geometric center of the remnant of up to 20%, although lower values of 10% are preferred. The best match with hydrodynamical simulations is achieved if Tycho is located at a large (3-4 kpc) distance in a medium with a mean preshock density of {approx}0.2 cm{sup -3}. Such preshock densities are obtained for highly ({approx}> 50%) porous ISM grains.

  5. Shocks in Dense Clouds in the Vela Supernova Remnant: FUSE

    NASA Technical Reports Server (NTRS)

    Nichols, Joy; Sonneborn, George (Technical Monitor)

    2002-01-01

    We have obtained 8 LWRS FUSE spectra to study a recently identified interaction of the Vela supernova remnant with a dense cloud region along its western edge. The goal is to quantify the temperature, ionization, density, and abundance characteristics associated with this shock/dense cloud interface by means of UV absorption line studies. Our detection of high-velocity absorption line C I at +90 to +130 km/s with IUE toward a narrow region interior to the Vela SNR strongly suggests the Vela supernova remnant is interacting with a dense ISM or molecular cloud. The shock/dense cloud interface is suggested by (1) the rarity of detection of high-velocity C I seen in IUE spectra, (2) its very limited spatial distribution in the remnant, and (3) a marked decrease in X-ray emission in the region immediately west of the position of these stars where one also finds a 100 micron emission ridge in IRAS images. We have investigated the shock physics and general properties of this interaction region through a focussed UV absorption line study using FUSE spectra. We have FUSE data on OVI absorption lines observed toward 8 stars behind the Vela supernova remnant (SNR). We compare the OVI observations with IUE observations of CIV absorption toward the same stars. Most of the stars, which are all B stars, have complex continua making the extraction of absorption lines difficult. Three of the stars, HD 72088, HD 72089 and HD 72350, however, are rapid rotators (v sin i less than 100 km/s) making the derivation of absorption column densities much easier. We have measured OVI and CIV column densities for the "main component" (i.e. the low velocity component) for these stars. In addition, by removing the H2 line at 1032.35A (121.6 km/s relative to OVI), we find high velocity components of OVI at approximately 150 km/s that we attribute to the shock in the Vela SNR. The column density ratios and magnitudes are compared to both steady shock models and results of hydrodynamical SNR

  6. Expansion of the Optical Remnant from Tycho’s Supernova

    NASA Astrophysics Data System (ADS)

    Putko, Joseph; Winkler, P. Frank; Blair, William P.

    2015-01-01

    Tycho's supernova remnant (SNR) is the expanding remnant from SN 1572, the penultimate Galactic supernova to have been recorded by contemporary observers. Its optical light is almost exclusively faint hydrogen Balmer emission around the periphery of the SNR, produced where fast nonradiative shocks encounter partly neutral preshock interstellar material. A variety of filaments, presumably thin sheets oriented tangentially, surround about one-third of the radio/X-ray shell. We have used CCD images, taken from KPNO over seven epochs from 1986 to 2009, to give the first optical expansion measurement of Tycho's SNR of the CCD era. Thirty filaments were identified and measured; the majority of them are at or near the remnant's outer rim and have proper motions from 0.19‧‧ ± 0.01‧‧ yr-1 to 0.26‧‧ ± 0.02‧‧ yr-1. The associated expansion indices, defined as the ratio of the current expansion rate to the historical mean, range from 0.35 ± 0.03 to 0.52 ± 0.05. Our measurements are consistent with those from the classic study by Kamper & van den Bergh (1978, ApJ, 224, 851) for the same filaments, but the CCD measurements have higher precision, and we have measured several additional fainter filaments. For direct comparison with X-ray and radio measurements, we selected the subset of optical filaments lying exactly at the outer rim, as identified in Chandra and VLA images. Considering only these filaments, virtually all have expansion indices greater than 0.40, the Sedov value. In addition to the rim filaments, there are several seen in the interior (in projection) that have smaller proper motions; these may have been decelerated, and/or they could be directed non-tangentially. Our final epoch of images, taken from the 3.5m WIYN telescope in 2009, reveals previously undetected extremely faint optical emission surrounding well over half of the remnant shell. This newly detected faint emission agrees well with the limb as defined in X-ray and radio images

  7. Optical observation of supernova remnant in elliptical galaxy NGC 185

    NASA Astrophysics Data System (ADS)

    Vučetić, M.; Arbutina, B.; Pavlovic, M. Z.; Ciprijanovic, A.; Urosevic, D.; Petrov, N.; Onić, D.; Trcka, A.

    2016-06-01

    In this paper we discuss the previously known optical supernova remnant (SNR) in NGC 185 galaxy, a dwarf elliptical companion of the Andromeda galaxy, in order to gain more information about its properties and evolutionary status. To this end, we observed a central portion of NGC 185, through the narrowband Hα and [SII]} filters, on a 2m RCC-telescope at National astronomical observatory Rozhen, Bulgaria. Also, we performed MHD simulations using the Pluto code, for the case of low environmental density and high pressure, in order to discuss evolution of a SNR in a gas poor dwarf galaxy.

  8. Core-collapse supernova remnants and interactions with their surroundings

    NASA Astrophysics Data System (ADS)

    Brantseg, Thomas Felton

    This thesis examines three core-collapse supernova remnants (SNR)---the Cygnus Loop in the Milky Way and 0453-68.5 and 0540-69.3 in the Large Magellanic Cloud---of varying ages and in varying states of interaction with the surrounding interstellar medium (ISM), using X-ray imaging spectroscopy with Chandra and supplemental data from other wavelengths. We use results from our analysis to address three main questions. First, we examine the applicability of the common Sedov-Taylor adiabatic blast wave model to core-collapse supernovae. Second, we determine the elemental abundances around the shell of these supernova remnants to determine if the use of SNRs as a gauge of abundances in the ISM is justified. Finally, we examine the pulsar wind nebulae (PWNe) in 0453-68.5 and 0540-69.3 and search for evidence of interaction between these PWNe and their immediate surroundings. We see highly inhomogeneous ISM surrounding all three surveyed SNRs, contrary to the key assumption in the Sedov-Taylor model of a uniform surrounding medium. In all three studied SNRs, we find that shock speeds are dependent on the density of the surrounding material. As subsidiary results, we also find depleted elemental abundances of oxygen, magnesium, and silicon, relative to typical ISM, around all three studied supernova remnants. Although this subsidiary result is not conclusive, we believe that it merits a followup study. In 0540-69.3 and 0453-68.5, which contain central pulsars, we find that the explosion directionality, which can be inferred from the pulsar's proper motion relative to the SNR, is not related to the morphology of the SNR itself. We conclude from this that the asymmetric shapes common in core-collapse supernova remnants can be more a function of the complex environments surrounding the progenitors of core-collapse supernovae than of the supernova explosions themselves. Finally, we see that the PWN in 0453-68.5 shows signs of having mixed with the surrounding thermal- emitting

  9. Minimum length, extra dimensions, modified gravity and black hole remnants

    SciTech Connect

    Maziashvili, Michael

    2013-03-01

    We construct a Hilbert space representation of minimum-length deformed uncertainty relation in presence of extra dimensions. Following this construction, we study corrections to the gravitational potential (back reaction on gravity) with the use of correspondingly modified propagator in presence of two (spatial) extra dimensions. Interestingly enough, for r→0 the gravitational force approaches zero and the horizon for modified Schwarzschild-Tangherlini space-time disappears when the mass approaches quantum-gravity energy scale. This result points out to the existence of zero-temperature black hole remnants in ADD brane-world model.

  10. Remnant percolative disorder in highly-cured networks

    SciTech Connect

    Adolf, D.; Hance, B.; Martin, J.E. )

    1993-05-24

    The authors have previously reported viscoelastic measurements demonstrating that fully-cured networks and critical gels exhibit similar relaxation spectra, implying that fully-cured networks are somewhat ill- connected. Here, they present restricted valence percolation simulations of networks well beyond the percolation transition that explicitly display remnant disorder over length scales less than the correlation length of the network. They conclude that the topology of highly-cured networks is not well described by a regular three- dimensional tennis net but is ill-connected over length scales that correspond to relaxation modes of practical interest.

  11. Final remnant of binary black hole mergers: Multipolar analysis

    SciTech Connect

    Owen, Robert

    2009-10-15

    Methods are presented to define and compute source multipoles of dynamical horizons in numerical relativity codes, extending previous work in the isolated and dynamical horizon formalisms to allow for horizons that are not axisymmetric. These methods are then applied to a binary black hole merger simulation, providing evidence that the final remnant is a Kerr black hole, both through the (spatially) gauge-invariant recovery of the geometry of the apparent horizon, and through a detailed extraction of quasinormal ringing modes directly from the strong-field region.

  12. Re-Tensioning Technique to Cover the Graft With Remnant in Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Noh, Jung Ho; Yoon, Kyoung Ho; Song, Sang Jun; Roh, Young Hak

    2014-01-01

    A number of remnant-preserving techniques to restore proprioceptive function in anterior cruciate ligament reconstruction have been described. However, they might not cover the significant amount of the graft with the synovium of the remnant in many cases. We introduce a simple technique that can cover nearly the entire graft with the synovium by re-tensioning the remnant, which might enhance synovialization of the graft and restoration of proprioception. PMID:25685673

  13. A high sensitivity search for X-rays from supernova remnants in Aquila

    NASA Technical Reports Server (NTRS)

    Schwartz, D. A.; Bleach, D. A.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.

    1972-01-01

    A high sensitivity scan of the galactic plane was performed to search for 2-20 keV X-rays from supernova remnants. The spectra of five X-ray sources detected between 44 deg and 31 deg longitude, of which only two might be associated with suggested supernova remnants, are reported on. Upper limits are presented for the 19 possible supernova remnants scanned in this survey.

  14. Remnant Trees Affect Species Composition but Not Structure of Tropical Second-Growth Forest

    PubMed Central

    Sandor, Manette E.; Chazdon, Robin L.

    2014-01-01

    Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields. PMID:24454700

  15. Remnant trees affect species composition but not structure of tropical second-growth forest.

    PubMed

    Sandor, Manette E; Chazdon, Robin L

    2014-01-01

    Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2-3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests ("control plots"). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields.

  16. Seafood delicacy makes great adhesive

    ScienceCinema

    Idaho National Laboratory - Frank Roberto, Heather Silverman

    2016-07-12

    Technology from Mother Nature is often hard to beat, so Idaho National Laboratory scientistsgenetically analyzed the adhesive proteins produced by blue mussels, a seafood delicacy. Afterobtaining full-length DNA sequences encoding these proteins, reprod

  17. Seafood delicacy makes great adhesive

    SciTech Connect

    Idaho National Laboratory - Frank Roberto, Heather Silverman

    2008-03-26

    Technology from Mother Nature is often hard to beat, so Idaho National Laboratory scientistsgenetically analyzed the adhesive proteins produced by blue mussels, a seafood delicacy. Afterobtaining full-length DNA sequences encoding these proteins, reprod

  18. A survey for Galactic supernova remnant/molecular cloud interactions ssing carbon monoxide

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Charles; Rieke, George; Bieging, John

    2016-06-01

    Supernova remnants are one of the primary engines through which stars add energy to the interstellar medium. The efficiency of this transfer of energy is enhanced where supernova remnants encounter dense interstellar gas, such as in molecular clouds. Unique signatures have been observed toward these supernova remnant/molecular cloud interactions in the form of unusual molecular line profiles and bright non-thermal radiation. The sites of these interactions also provide some of the best examples for evidence of cosmic-ray acceleration and Galactic sources of very high-energy gamma-rays. Despite the large number of individual studies that examine supernova remnant/molecular cloud interactions, very little is known about their overall rates and characteristics. This lack of information limits the usefulness of individual supernova remnant/molecular cloud interactions to enhance our understanding of supernova feedback and cosmic-ray acceleration. I will discuss recent work studying large populations of supernova remnants in the 12CO J = 2 ‑ 1 and J = 3 ‑ 2 lines and the observational signatures associated with molecular shocks from supernova ejecta. Broadened molecular lines and molecular line ratios indicative of warm gas can be used to identify and characterize populations of supernova remnant/molecular cloud interactions. From this large sample, I will discuss new constraints on the energetic processes to which supernova remnants contribute, especially the rate of GeV and TeV gamma-ray production associated with supernova remnant/molecular cloud interfaces.

  19. G29.7-0.3: another supernova remnant with an identity crisis

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Helfand, D. J.; Szymkowiak, A. E.

    1983-01-01

    New radio and X-ray observations of the galactic supernova remnant G29.7-0.3 show that it is composed of two spectrally distinct components: a steep-spectrum, incomplete shell 3 arcmin in extent enclosing a flat-spectrum, X-ray emitting region 30 arcsec across. Thus, G29.7-0.3 joins the ranks of supernova remnants which exhibit a combination of Crab-like and shell remnant attributes. The Crab-like core has the highest ratio of X-ray radio luminosity of all the Crab-like remnants observed to date, suggesting that it is an extremely young object.

  20. Adhesive interactions between vesicles in the strong adhesion limit

    PubMed Central

    Ramachandran, Arun; Anderson, Travers H.; Leal, L. Gary; Israelachvili, Jacob N.

    2010-01-01

    We consider the adhesive interaction energy between a pair of vesicles in the strong adhesion limit, in which bending forces play a negligible role in determining vesicle shape compared to forces due to membrane stretching. Although force-distance or energy distance relationships characterizing adhesive interactions between fluid bilayers are routinely measured using the surface forces apparatus, the atomic force microscope and the biomembrane force probe, the interacting bilayers in these methods are supported on surfaces (e.g. mica sheet) and cannot be deformed. However, it is known that in a suspension, vesicles composed of the same bilayer can deform by stretching or bending, and can also undergo changes in volume. Adhesively interacting vesicles can thus form flat regions in the contact zone, which will result in an enhanced interaction energy as compared to rigid vesicles. The focus of this paper is to examine the magnitude of the interaction energy between adhesively interacting, deformed vesicles relative to free, undeformed vesicles as a function of the intervesicle separation. The modification of the intervesicle interaction energy due to vesicle deformability can be calculated knowing the undeformed radius of the vesicles, R0, the bending modulus kb, the area expansion modulus Ka, and the adhesive minimum WP(0) and separation DP(0) in the energy of interaction between two flat bilayers, which can be obtained from the force-distance measurements made using the above supported-bilayer methods. For vesicles with constant volumes, we show that adhesive potentials between non-deforming bilayers such as ∣WP(0)∣∼5×10−4mJ/m2, which are ordinarily considered weak in colloidal physics literature, can result in significantly deep (>10×) energy minima due to increase in vesicle area and flattening in the contact region. If the osmotic expulsion of water across the vesicles driven by the tense, stretched membrane in the presence of an osmotically active

  1. Adhesive interactions between vesicles in the strong adhesion limit.

    PubMed

    Ramachandran, Arun; Anderson, Travers H; Leal, L Gary; Israelachvili, Jacob N

    2011-01-01

    We consider the adhesive interaction energy between a pair of vesicles in the strong adhesion limit, in which bending forces play a negligible role in determining vesicle shape compared to forces due to membrane stretching. Although force−distance or energy−distance relationships characterizing adhesive interactions between fluid bilayers are routinely measured using the surface forces apparatus, the atomic force microscope, and the biomembrane force probe, the interacting bilayers in these methods are supported on surfaces (e.g., mica sheet) and cannot be deformed. However, it is known that, in a suspension, vesicles composed of the same bilayer can deform by stretching or bending, and can also undergo changes in volume. Adhesively interacting vesicles can thus form flat regions in the contact zone, which will result in an enhanced interaction energy as compared to rigid vesicles. The focus of this paper is to examine the magnitude of the interaction energy between adhesively interacting, deformed vesicles relative to free, undeformed vesicles as a function of the intervesicle separation. The modification of the intervesicle interaction energy due to vesicle deformability can be calculated knowing the undeformed radius of the vesicles, R0, the bending modulus, k(b), the area expansion modulus, k(a), and the adhesive minimum, W(P)(0), and separation, D(P)(0), in the energy of interaction between two flat bilayers, which can be obtained from the force−distance measurements made using the above supported-bilayer methods. For vesicles with constant volumes, we show that adhesive potentials between nondeforming bilayers such as |W(P)(0)| 5 × 10(−4) mJ/m2, which are ordinarily considered weak in the colloidal physics literature, can result in significantly deep (>10×) energy minima due to increase in vesicle area and flattening in the contact region. If the osmotic expulsion of water across the vesicles driven by the tense, stretched membrane in the presence

  2. Mechanisms of adhesion in geckos.

    PubMed

    Autumn, Kellar; Peattie, Anne M

    2002-12-01

    The extraordinary adhesive capabilities of geckos have challenged explanation for millennia, since Aristotle first recorded his observations. We have discovered many of the secrets of gecko adhesion, yet the millions of dry, adhesive setae on the toes of geckos continue to generate puzzling new questions and valuable answers. Each epidermally-derived, keratinous seta ends in hundreds of 200 nm spatular tips, permitting intimate contact with rough and smooth surfaces alike. Prior studies suggested that adhesive force in gecko setae was directly proportional to the water droplet contact angle (θ) , an indicator of the free surface energy of a substrate. In contrast, new theory suggests that adhesion energy between a gecko seta and a surface (W(GS)) is in fact proportional to (1 + cosθ), and only for θ > 60°. A reanalysis of prior data, in combination with our recent study, support the van der Waals hypothesis of gecko adhesion, and contradict surface hydrophobicity as a predictor of adhesion force. Previously, we and our collaborators measured the force production of a single seta. Initial efforts to attach a seta failed because of improper 3D orientation. However, by simulating the dynamics of gecko limbs during climbing (based on force plate data) we discovered that, in single setae, a small normal preload, combined with a 5 μm displacement yielded a very large adhesive force of 200 microNewton (μN), 10 times that predicted by whole-animal measurements. 6.5 million setae of a single tokay gecko attached maximally could generate 130 kg force. This raises the question of how geckos manage to detach their feet in just 15 ms. We discovered that simply increasing the angle that the setal shaft makes with the substrate to 30° causes detachment. Understanding how simultaneous attachment and release of millions of setae are controlled will require an approach that integrates levels ranging from molecules to lizards.

  3. Silorane adhesive system: a case report.

    PubMed

    Ruschel, Vanessa Carla; Baratieri, Luiz Narciso; Monteiro Júnior, Sylvio; Andrada, Mauro Amaral Caldeira de

    2014-01-01

    Silorane-based composite resin requires a specific adhesive system: a 2-step self-etching adhesive. Clinical protocols are well established and are based on the principles of adhesion to mineralized dental tissues. In this paper, we present a clinical application of the silorane adhesive system in a class-II restoration using silorane-based composite resin.

  4. How to explant a diseased liver for living donor liver transplantation after previous gastrectomy with severe adhesion (with video).

    PubMed

    Eguchi, Susumu; Soyama, Akihiko; Takatsuki, Mitsuhisa; Hidaka, Masaaki; Adachi, Tomohiko; Kitasato, Amane; Baimakhanov, Zhassulan; Kuroki, Tamotsu

    2014-08-01

    We performed living donor liver transplantation (LDLT) in a patient who had undergone distal gastrectomy for gastric ulcer disease with Billroth I reconstruction 30 years before the LDLT. The adhesion was very severe between remnant stomach and hepatic hilum as well as left liver lobe with shortening of hepatoduodenal structures. After dissection of the infrahepatic inferior vena cava, the Spiegel lobe was identified from the dorsal side. The Spiegel lobe was then penetrated with a right angle dissector so that a plastic tape could be placed around the whole adhesion, including important structures in the hepatoduodenal ligament. Next, the right hepatic vein was transected with a vascular stapler using Pringle's maneuver using the plastic tape to fasten the entire adhesional structure. Subsequently, the trunk of the middle and left hepatic vein was transected after clamping. The remaining short hepatic veins in the left side were divided completely from the cranial to the caudal direction to dissect Spiegel's lobe. Finally, the hepatoduodenal ligament was identified from the attached remnant stomach and the duodenum and a vascular clamp was placed on the entire hepatoduaodenal ligament. Finally, the diseased liver was explanted for graft implantation. Thus, retrograde explantation of the liver was effective in decreasing the risk of damaging vital elements in the hepatoduodenal ligament, the remnant stomach, and the duodenum.

  5. An XMM-Newton Study of the Mixed-morphology Supernova Remnant W28 (G6.4-0.1)

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Safi-Harb, Samar; Chen, Yang; Zhang, Xiao; Jiang, Bing; Ferrand, Gilles

    2014-08-01

    We have performed an XMM-Newton imaging and spectroscopic study of supernova remnant (SNR) W28, a prototype mixed-morphology or thermal composite SNR believed to be interacting with a molecular cloud. The observed hot X-ray emitting plasma is characterized by low metal abundances, showing no evidence of ejecta. The X-rays arising from the deformed northeastern shell consist of a thermal component with a temperature of ~0.3 keV plus a hard component of either thermal (temperature ~0.6 keV) or non-thermal (photon index = 0.9-2.4) origin. The X-ray emission in the SNR interior is blobby and the corresponding spectra are best described as the emission from a cold (~0.4 keV) plasma in non-equilibrium ionization with an ionization timescale of ~4.3 × 1011 cm-3 s plus a hot (~0.8 keV) gas in collisional ionization equilibrium. Applying the two-temperature model to the smaller central regions, we find non-uniform interstellar absorption, temperature, and density distribution, which indicates that the remnant is evolving in a non-uniform environment with denser material in the east and north. The cloudlet evaporation mechanism can essentially explain the properties of the X-ray emission in the center, and thermal conduction may also play a role for length scales comparable to the remnant radius. A recombining plasma model with an electron temperature of ~0.6 keV is also feasible for describing the hot central gas with the recombination age of the gas estimated at ~2.9 × 104 yr.

  6. Fibrillar Adhesive for Climbing Robots

    NASA Technical Reports Server (NTRS)

    Pamess, Aaron; White, Victor E.

    2013-01-01

    A climbing robot needs to use its adhesive patches over and over again as it scales a slope. Replacing the adhesive at each step is generally impractical. If the adhesive or attachment mechanism cannot be used repeatedly, then the robot must carry an extra load of this adhesive to apply a fresh layer with each move. Common failure modes include tearing, contamination by dirt, plastic deformation of fibers, and damage from loading/ unloading. A gecko-like fibrillar adhesive has been developed that has been shown useful for climbing robots, and may later prove useful for grasping, anchoring, and medical applications. The material consists of a hierarchical fibrillar structure that currently contains two levels, but may be extended to three or four levels in continuing work. The contacting level has tens of thousands of microscopic fibers made from a rubberlike material that bend over and create intimate contact with a surface to achieve maximum van der Waals forces. By maximizing the real area of contact that these fibers make and minimizing the bending energy necessary to achieve that contact, the net amount of adhesion has been improved dramatically.

  7. [Probe into the platelets adhesion to carbonaceous biomaterials].

    PubMed

    Li, Bogang; Na, Juanjuan; Yin, Guangfu; Yin, Jie; Zheng, Changqiong

    2004-02-01

    In order to clarify the mechanism of blood coagulation for carbonaceous biomaterials, the plasma rich in platelet was obtaining through the centrifugation of fresh human blood containing anticoagulant. Adhesive tests of platelets to surfaces of DLC, diamond film(DF) and graphite was carried out at 37 degrees C. Then, morphology observation, counting and deformation index calculation of the platelets adhering to surfaces of the three kinds of materials were analyzed by SEM. It has been shown that there is no any platelet on the surface of DLC, but on DF and graphite, a lot of platelets are observed with serious deformation of type III-V. The adhesive amounts of platelet on the surface of graphite are more than those on DF, but deformation index of platelets on the surface of DF is more than that on graphite. Three major conclusions have been obtained through comparative analyses with our previous researches and related literatures: (1) Adhesion, deformation and collection of platelets occurred in succession on material surfaces resulting from protein adsorption are the major mechanism of blood coagulation of carbonaceous materials; (2) Deformation degree of platelets is more important hemocompatibility index than consumption ratio of platelets for carbonaceous materials; (3) The purer the DLC, the better is the hemocompatibility. These conclusions possess important directive function for improving and designing carbonaceous materials used in artificial mechanical heart valves.

  8. Focal adhesion kinase

    PubMed Central

    Stone, Rebecca L; Baggerly, Keith A; Armaiz-Pena, Guillermo N; Kang, Yu; Sanguino, Angela M; Thanapprapasr, Duangmani; Dalton, Heather J; Bottsford-Miller, Justin; Zand, Behrouz; Akbani, Rehan; Diao, Lixia; Nick, Alpa M; DeGeest, Koen; Lopez-Berestein, Gabriel; Coleman, Robert L; Lutgendorf, Susan; Sood, Anil K

    2014-01-01

    This investigation describes the clinical significance of phosphorylated focal adhesion kinase (FAK) at the major activating tyrosine site (Y397) in epithelial ovarian cancer (EOC) cells and tumor-associated endothelial cells. FAK gene amplification as a mechanism for FAK overexpression and the effects of FAK tyrosine kinase inhibitor VS-6062 on tumor growth, metastasis, and angiogenesis were examined. FAK and phospho-FAKY397 were quantified in tumor (FAK-T; pFAK-T) and tumor-associated endothelial (FAK-endo; pFAK-endo) cell compartments of EOCs using immunostaining and qRT-PCR. Associations between expression levels and clinical variables were evaluated. Data from The Cancer Genome Atlas were used to correlate FAK gene copy number and expression levels in EOC specimens. The in vitro and in vivo effects of VS-6062 were assayed in preclinical models. FAK-T and pFAK-T overexpression was significantly associated with advanced stage disease and increased microvessel density (MVD). High MVD was observed in tumors with elevated endothelial cell FAK (59%) and pFAK (44%). Survival was adversely affected by FAK-T overexpression (3.03 vs 2.06 y, P = 0.004), pFAK-T (2.83 vs 1.78 y, P < 0.001), and pFAK-endo (2.33 vs 2.17 y, P = 0.005). FAK gene copy number was increased in 34% of tumors and correlated with expression levels (P < 0.001). VS-6062 significantly blocked EOC and endothelial cell migration as well as endothelial cell tube formation in vitro. VS-6062 reduced mean tumor weight by 56% (P = 0.005), tumor MVD by 40% (P = 0.0001), and extraovarian metastasis (P < 0.01) in orthotopic EOC mouse models. FAK may be a unique therapeutic target in EOC given the dual anti-angiogenic and anti-metastatic potential of FAK inhibitors. PMID:24755674

  9. Extremely fast acceleration of cosmic rays in a supernova remnant.

    PubMed

    Uchiyama, Yasunobu; Aharonian, Felix A; Tanaka, Takaaki; Takahashi, Tadayuki; Maeda, Yoshitomo

    2007-10-01

    Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of the SNR RX J1713.7-3946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RX J1713.7-3946 indicate that electron acceleration proceeds in the most effective ('Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1 PeV (10(15) eV) and beyond in young supernova remnants.

  10. Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves

    NASA Technical Reports Server (NTRS)

    Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.

    2015-01-01

    Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities 200 km s(exp -1) for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of approximately 2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of approximately 3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of approximately 2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.

  11. Tycho's Remnant Provides Shocking Evidence for Cosmic Rays

    NASA Astrophysics Data System (ADS)

    2005-09-01

    Astronomers have found compelling evidence that a supernova shock wave has produced a large amount of cosmic rays, particles of mysterious origin that constantly bombard the Earth. This discovery, made with NASA's Chandra X-ray Observatory, supports theoretical arguments that shock waves from stellar explosions may be a primary source of cosmic rays. This finding is important for understanding the origin of cosmic rays, which are atomic nuclei that strike the Earth's atmosphere with very high energies. Scientists believe that some are produced by flares on the Sun, and others by similar events on other stars, or pulsars or black hole accretion disks. But, one of the prime suspects has been supernova shock waves. Now, a team of astronomers has used Chandra observations of Tycho's supernova remnant to strengthen the case for this explanation. "With only a single object involved we can't state with confidence that supernova shock waves are the primary source of cosmic rays," said John P. Hughes of Rutgers University in Piscataway, New Jersey, and coauthor of a report to be published in an upcoming issue of The Astrophysical Journal. "What we have done is present solid evidence that the shock wave in at least one supernova remnant has accelerated nuclei to cosmic ray energies." In the year 1572, the Danish astronomer Tycho Brahe observed and studied the sudden appearance of a bright "new star" in the constellation Cassiopeia. Now known as Tycho's supernova remnant, the event created a sensation in Tycho's time because it exploded the myth that stars never change. Four centuries later, the Chandra results on Tycho's remnant show that some modern ideas of the aftermath of supernova explosions may have to be revised. The report by Hughes and colleagues demonstrates that the shock wave produced by the explosive disruption of the star behaves in a way that cannot be explained by the standard theory. The supernova debris is observed to expand at a speed of about six million

  12. Tycho's Remnant Provides Shocking Evidence for Cosmic Rays

    NASA Astrophysics Data System (ADS)

    2005-09-01

    Astronomers have found compelling evidence that a supernova shock wave has produced a large amount of cosmic rays, particles of mysterious origin that constantly bombard the Earth. This discovery, made with NASA's Chandra X-ray Observatory, supports theoretical arguments that shock waves from stellar explosions may be a primary source of cosmic rays. This finding is important for understanding the origin of cosmic rays, which are atomic nuclei that strike the Earth's atmosphere with very high energies. Scientists believe that some are produced by flares on the Sun, and others by similar events on other stars, or pulsars or black hole accretion disks. But, one of the prime suspects has been supernova shock waves. Now, a team of astronomers has used Chandra observations of Tycho's supernova remnant to strengthen the case for this explanation. "With only a single object involved we can't state with confidence that supernova shock waves are the primary source of cosmic rays," said John P. Hughes of Rutgers University in Piscataway, New Jersey, and coauthor of a report to be published in an upcoming issue of The Astrophysical Journal. "What we have done is present solid evidence that the shock wave in at least one supernova remnant has accelerated nuclei to cosmic ray energies." In the year 1572, the Danish astronomer Tycho Brahe observed and studied the sudden appearance of a bright "new star" in the constellation Cassiopeia. Now known as Tycho's supernova remnant, the event created a sensation in Tycho's time because it exploded the myth that stars never change. Four centuries later, the Chandra results on Tycho's remnant show that some modern ideas of the aftermath of supernova explosions may have to be revised. The report by Hughes and colleagues demonstrates that the shock wave produced by the explosive disruption of the star behaves in a way that cannot be explained by the standard theory. The supernova debris is observed to expand at a speed of about six million

  13. Searches for Continuous Gravitational Waves from Nine Young Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Gossler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.; Howell, E. J.; Hu, Y. M.; Huerta, E.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Islas, G.; Isler, J. C.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacobson, M.; Jang, H.; Jaranowski, P.; Jawahar, S.; Ji, Y.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Keiser, G. M.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, C.; Kim, K.; Kim, N. G.; Kim, N.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, A.; Kumar, P.; Kuo, L.; Kutynia, A.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Lazzaro, C.; Le, J.; Leaci, P.; Leavey, S.; Lebigot, E.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B.; Lewis, J.; Li, T. G. F.; Libbrecht, K.; Libson, A.; Lin, A. C.; Littenberg, T. B.; Lockerbie, N. A.; Lockett, V.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macarthur, J.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña na-Sandoval, F.; Magee, R.; Mageswaran, M.; Maglione, C.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mangano, V.; Mansell, G. L.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McLin, K.; McWilliams, S.; Meacher, D.; Meadors, G. D.; Meidam, J.; Meinders, M.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Moggi, A.; Mohan, M.; Mohanty, S. D.; Mohapatra, S. R. P.; Moore, B.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, I.; Neri, M.; Newton, G.; Nguyen, T.; Nielsen, A. B.; Nissanke, S.; Nitz, A. H.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; Oram, R.; O'Reilly, B.; Ortega, W.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Pai, S.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patrick, Z.; Pedraza, M.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Post, A.; Poteomkin, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qin, J.; Quetschke, V.; Quintero, E.; Quiroga, G.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramirez, K.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Reula, O.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Saleem, M.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J. R.; Sannibale, V.; Santiago-Prieto, I.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Sawadsky, A.; Scheuer, J.; Schilling, R.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Sevigny, A.; Shaddock, D. A.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L.; Singh, R.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Son, E. J.; Sorazu, B.; Souradeep, T.; Staley, A.; Stebbins, J.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Steplewski, S.; Stevenson, S.; Stone, R.; Strain, K. A.; Straniero, N.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sutton, P. J.; Swinkels, B.; Szczepanczyk, M.; Szeifert, G.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Tellez, G.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Tshilumba, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, H.; Wang, M.; Wang, X.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; White, D. J.; Whiting, B. F.; Wilkinson, C.; Williams, L.; Williams, R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Xie, S.; Yablon, J.; Yakushin, I.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yang, Q.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, Fan; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhu, X. J.; Zucker, M. E.; Zuraw, S.; Zweizig, J.

    2015-11-01

    We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering {F}-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10-25 on intrinsic strain, 2 × 10-7 on fiducial ellipticity, and 4 × 10-5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.

  14. Searches for Continuous Gravitational Waves from Nine Young Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M., Jr.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D’Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Gossler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.; Howell, E. J.; Hu, Y. M.

    2015-11-01

    We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3–25.3 days using the matched-filtering {F}-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10‑25 on intrinsic strain, 2 × 10‑7 on fiducial ellipticity, and 4 × 10‑5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.

  15. Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae

    SciTech Connect

    Funk, S.; /KIPAC, Menlo Park

    2007-09-26

    Shell-type Supernova remnants (SNRs) have long been known to harbour a population of ultra-relativistic particles, accelerated in the Supernova shock wave by the mechanism of diffusive shock acceleration. Experimental evidence for the existence of electrons up to energies of 100 TeV was first provided by the detection of hard X-ray synchrotron emission as e.g. in the shell of the young SNR SN1006. Furthermore using theoretical arguments shell-type Supernova remnants have long been considered as the main accelerator of protons - Cosmic rays - in the Galaxy; definite proof of this process is however still missing. Pulsar Wind Nebulae (PWN) - diffuse structures surrounding young pulsars - are another class of objects known to be a site of particle acceleration in the Galaxy, again through the detection of hard synchrotron X-rays such as in the Crab Nebula. Gamma-rays above 100 MeV provide a direct access to acceleration processes. The GLAST Large Area telescope (LAT) will be operating in the energy range between 30 MeV and 300 GeV and will provide excellent sensitivity, angular and energy resolution in a previously rather poorly explored energy band. We will describe prospects for the investigation of these Galactic particle accelerators with GLAST.

  16. Nonlinear Shock Acceleration and Photon Emission in Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Ellison, Donald C.; Berezhko, Evgeny G.; Baring, Matthew G.

    2000-01-01

    We have extended a simple model of nonlinear diffusive shock acceleration (Berezhko & Ellison 1999: Ellison &, Berezhko 1999a) to include the injection and acceleration of electrons and the production of photons from bremsstrahlung, synchrotron, inverse Compton, and pion-decay processes. We argue that, the results of this model, which is simpler to use than more elaborate ones, offer a significant improvement, over test-particle, power-law spectra which are often used in astrophysical applications of diffusive shock acceleration. With an evolutionary supernova remnant (SNR) model to obtain shock parameters as functions of ambient interstellar medium parameters and time, we predict broad-band continuum photon emission from supernova remnants in general, and SN1006 in particular, showing that our results compare well with the more complete time-dependent and spherically symmetric nonlinear model of Berezhko, Ksenofontov, & Petukhov (1999a). We discuss the implications nonlinear shock acceleration has for X-ray line emission, and use our model to describe how ambient conditions determine the TeV/radio flux ratio, an important parameter for gamma-ray observations of radio SNRs.

  17. Improved optical spectrophotometry of supernova remnants in M33

    NASA Technical Reports Server (NTRS)

    Blair, W. P.; Kirshner, R. P.

    1985-01-01

    Optical spectra of SNRs in M33 have been used to investigate abundance gradients and SNR evolution in this galaxy. Abundances of O, N, and S are derived from the spectra using new shock models by Dopita et al. (1984). The results for N and S show abundance gradients similar to those in NGC 300 and the Galaxy. The O abundances may be affected by possible contamination from H II regions and low-velocity shocks. Electron densities derived from the forbidden S II 6717 A/6731 A line ratio are used with a pressure equilibrium argument to estimate the initial explosion energy for each SNR. Evolutionary models for the remnants are investigated, and the distribution of the number of remnants with diameter is found to be consistent with free expansion of the SNRs to diameters of about 26 pc. The results may also be consistent with Sedov evolution if the ranges of initial supernova energies and surrounding interstellar medium densities are large enough.

  18. Extremely Fast Acceleration of Cosmic Rays in a Supernova Remnant

    SciTech Connect

    Uchiyama, Y.; Aharonian, F.A.; Tanaka, T.; Takahashi, T.; Maeda, Y.; /JAERI, Tokai /Dublin Inst. /Heidelberg, Max Planck Inst. /SLAC

    2007-10-23

    Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of theSNRRXJ1713.723946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RXJ1713.723946 indicate that electron acceleration proceeds in the most effective ('Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1 PeV (10{sup 15} eV) and beyond in young supernova remnants.

  19. Investigation of organic adhesives for hybrid microcircuits

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1975-01-01

    The properties of organic adhesives were investigated to acquire information for a guideline document regarding the selection of adhesives for use in high reliability hybrid microcircuits. Specifically, investigations were made of (1) alternate methods for determining the outgassing of cured adhesives, (2) effects of long term aging at 150 C on the electrical properties of conductive adhesives, (3) effects of shelf life age on adhesive characteristics, (4) bond strengths of electrically conductive adhesives on thick film gold metallization, (5) a copper filled adhesive, (6) effects of products outgassed from cured adhesives on device electrical parameters, (7) metal migration from electrically conductive adhesives, and (8) ionic content of electrically insulative adhesives. The tests performed during these investigations are described, and the results obtained are discussed.

  20. Proceedings of the 19th annual meeting of the Adhesion Society

    SciTech Connect

    Ward, T.C.

    1996-12-31

    This is the proceedings of the 19th Annual Meeting of the Adhesion Society, held February 18-21, 1996. Papers are presented on various aspects of adhesion, ranging from studies at the molecular level, to studies of the intermixing of polymer chains across interface joints, to the study of polymer/metal joints. Separate abstracts of articles from this proceedings have been indexed into the database.

  1. Plasma polymerization for cell adhesive/anti-adhesive implant coating

    NASA Astrophysics Data System (ADS)

    Meichsner, Juergen; Testrich, Holger; Rebl, Henrike; Nebe, Barbara

    2015-09-01

    Plasma polymerization of ethylenediamine (C2H8N2, EDA) and perfluoropropane (C3F8, PFP) with admixture of argon and hydrogen, respectively, was studied using an asymmetric 13.56 MHz CCP. The analysis of the plasma chemical gas phase processes for stable molecules revealed consecutive reactions: C2H8N2 consumption, intermediate product NH3, and main final product HCN. In C3F8- H2 plasma the precursor molecule C3F8 and molecular hydrogen are consumed and HF as well as CF4 and C2F6 are found as main gaseous reaction products. The deposited plasma polymer films on the powered electrode are strongly cross-linked due to ion bombardment. The stable plasma polymerized films from EDA are characterized by high content of nitrogen with N/C ratio of about 0.35. The plasma polymerized fluorocarbon film exhibit a reduced F/C ratio of about 1.2. Adhesion tests with human osteoblast cell line MG-63 on coated Ti6Al4V samples (polished) compared with uncoated reference sample yielded both, the enhanced cell adhesion for plasma polymerized EDA and significantly reduced cell adhesion for fluorocarbon coating, respectively. Aging of the plasma polymerized EDA film, in particular due to the reactions with oxygen from air, showed no significant change in the cell adhesion. The fluorocarbon coating with low cell adhesion is of interest for temporary implants. Funded by the Campus PlasmaMed.

  2. Optimizing Adhesive Design by Understanding Compliance.

    PubMed

    King, Daniel R; Crosby, Alfred J

    2015-12-23

    Adhesives have long been designed around a trade-off between adhesive strength and releasability. Geckos are of interest because they are the largest organisms which are able to climb utilizing adhesive toepads, yet can controllably release from surfaces and perform this action over and over again. Attempting to replicate the hierarchical, nanoscopic features which cover their toepads has been the primary focus of the adhesives field until recently. A new approach based on a scaling relation which states that reversible adhesive force capacity scales with (A/C)(1/2), where A is the area of contact and C is the compliance of the adhesive, has enabled the creation of high strength, reversible adhesives without requiring high aspect ratio, fibrillar features. Here we introduce an equation to calculate the compliance of adhesives, and utilize this equation to predict the shear adhesive force capacity of the adhesive based on the material components and geometric properties. Using this equation, we have investigated important geometric parameters which control force capacity and have shown that by controlling adhesive shape, adhesive force capacity can be increased by over 50% without varying pad size. Furthermore, we have demonstrated that compliance of the adhesive far from the interface still influences shear adhesive force capacity. Utilizing this equation will allow for the production of adhesives which are optimized for specific applications in commercial and industrial settings. PMID:26618537

  3. Optimizing Adhesive Design by Understanding Compliance.

    PubMed

    King, Daniel R; Crosby, Alfred J

    2015-12-23

    Adhesives have long been designed around a trade-off between adhesive strength and releasability. Geckos are of interest because they are the largest organisms which are able to climb utilizing adhesive toepads, yet can controllably release from surfaces and perform this action over and over again. Attempting to replicate the hierarchical, nanoscopic features which cover their toepads has been the primary focus of the adhesives field until recently. A new approach based on a scaling relation which states that reversible adhesive force capacity scales with (A/C)(1/2), where A is the area of contact and C is the compliance of the adhesive, has enabled the creation of high strength, reversible adhesives without requiring high aspect ratio, fibrillar features. Here we introduce an equation to calculate the compliance of adhesives, and utilize this equation to predict the shear adhesive force capacity of the adhesive based on the material components and geometric properties. Using this equation, we have investigated important geometric parameters which control force capacity and have shown that by controlling adhesive shape, adhesive force capacity can be increased by over 50% without varying pad size. Furthermore, we have demonstrated that compliance of the adhesive far from the interface still influences shear adhesive force capacity. Utilizing this equation will allow for the production of adhesives which are optimized for specific applications in commercial and industrial settings.

  4. Time-dependent shock acceleration of particles. Effect of the time-dependent injection, with application to supernova remnants

    NASA Astrophysics Data System (ADS)

    Petruk, O.; Kopytko, B.

    2016-11-01

    Three approaches are considered to solve the equation which describes the time-dependent diffusive shock acceleration of test particles at the non-relativistic shocks. At first, the solution of Drury for the particle distribution function at the shock is generalized to any relation between the acceleration time-scales upstream and downstream and for the time-dependent injection efficiency. Three alternative solutions for the spatial dependence of the distribution function are derived. Then, the two other approaches to solve the time-dependent equation are presented, one of which does not require the Laplace transform. At the end, our more general solution is discussed, with a particular attention to the time-dependent injection in supernova remnants. It is shown that, comparing to the case with the dominant upstream acceleration time-scale, the maximum momentum of accelerated particles shifts towards the smaller momenta with increase of the downstream acceleration time-scale. The time-dependent injection affects the shape of the particle spectrum. In particular, (i) the power-law index is not solely determined by the shock compression, in contrast to the stationary solution; (ii) the larger the injection efficiency during the first decades after the supernova explosion, the harder the particle spectrum around the high-energy cutoff at the later times. This is important, in particular, for interpretation of the radio and gamma-ray observations of supernova remnants, as demonstrated on a number of examples.

  5. G346.6-0.2: Non-thermal X-ray emission from a Mixed-Morphology Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Auchettl, K.; Wong, B. T. T.; Ng, C.-Y.; Slane, P.

    2016-06-01

    The detection of non-thermal X-ray emission from supernova remnants (SNRs) provides us with a unique window into studying particle acceleration at the shock-front. All of the 14 or so SNRs in which non-thermal X-ray synchrotron emission has been detected are shell-like in nature, and show no direct evidence of interaction with large nearby molecular clouds. Here we present a new X-ray study of the molecular cloud interacting mixed-morphology (MM) SNR G346.6-0.2 using XMM-Newton. We found that the X-ray emission arises from a cool recombining plasma with sub-solar abundances, confirming previous Suzaku results. In addition, we identified an additional power-law component in the spectrum, with a photon index of ˜2. We investigated its possible origin and conclude that it most likely arises from synchrotron emission produced by particles accelerated at the shock. This makes G346.6-0.2 an important new object in the class of synchrotron emitting SNRs, as unlike shell type X-ray synchrotron SNRs, MM SNRs are usually thought to have shock velocities that are effectively too slow to accelerate electrons. The dense environment and nature of the remnant, provide conditions unseen in shell type X-ray synchrotron SNRs, providing a unique opportunity to study the effect that these properties have on the production of X-ray synchrotron emission.

  6. G346.6-0.2: The Mixed-Morphology Supernova Remnant with Non-Thermal X-Ray Emission

    NASA Astrophysics Data System (ADS)

    Auchettl, Katie; Slane, Patrick; Ng, Stephen C.-Y.; Wong, B. T. T.

    2016-07-01

    The detection of non-thermal X-ray emission from supernova remnants (SNRs) provides us with a unique window into studying particle acceleration at the shock-front. All of the 14 or so SNRs in which non-thermal X-ray synchrotron emission has been detected are shell-like in nature, and show no evidence of interaction with large nearby molecular clouds. Here we present a new X-ray study of the molecular cloud interacting mixed-morphology (MM) SNR G346.6-0.2 using XMM-Newton. We found that the X-ray emission arises from a cool recombining plasma with subsolar abundances, confirming previous Suzaku results. In addition, we identified an additional power-law component in the spectrum, with a photon index of ˜2. We investigated its possible origin and conclude that it most likely arises from synchrotron emission produced by particles accelerated at the shock. This makes G346.6-0.2 an important new object in the class of synchrotron emitting SNRs, as unlike shell type X-ray synchrotron SNRs, MM SNRs are usually thought to have shock velocities that are effectively too slow to accelerate electrons. The dense environment and nature of the remnant, provide conditions unseen in shell type X-ray synchrotron SNRs, providing a unique opportunity to study the effect that these properties have on the production of X-ray synchrotron emission.

  7. Expansion of the supernova remnant 3C 10 /Tycho/ and its implications for models of young remnants

    NASA Astrophysics Data System (ADS)

    Strom, R. G.; Goss, W. M.; Shaver, P. A.

    1982-08-01

    The remnant of Tycho Brahe's supernova (3C 10) was observed with the Westerbork telescope at 21 cm in 1971 and 1979, and these measurements have been used to determine the radial expansion rate. The average value obtained is within 0.026 of 0.256 arcsec/yg, with the individual radio and optical data points agreeing well within the errors. The apparent discrepancy in average values is primarily the result of a low expansion speed at the position of the most prominent nebulosity, and this is attributed to deceleration caused by the higher density of material. While the expansion speed only marginally exceeds that predicted by the Sedov solution, the confirmation lent by the optical data suggests a possible real effect. Either the remnant is not yet fully in the adiabatic phase, or the dynamics are being modified by the evaporation of neutral material behind the shock front. It is clear that swept-up material now dominates the dynamics of 3C 10. No significant change in flux density was detected at a level which favors models where particle acceleration/field amplification are occurring over that of simple adiabatic expansion.

  8. Innovative Electrostatic Adhesion Technologies

    NASA Astrophysics Data System (ADS)

    Gagliano, L.; Bryan, T.; Williams, S.; McCoy, B.; MacLeod, T.

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development

  9. Innovative Electrostatic Adhesion Technologies

    NASA Technical Reports Server (NTRS)

    Bryan, Tom; Macleod, Todd; Gagliano, Larry; Williams, Scott; McCoy, Brian

    2015-01-01

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and

  10. Elastocapilllarity in insect adhesion: the case of beetle adhesive hair

    NASA Astrophysics Data System (ADS)

    Gernay, Sophie; Gilet, Tristan; Lambert, Pierre; Federle, Walter

    2014-11-01

    The feet of many insects are covered with dense arrays of hair-like structures called setae. Liquid capillary bridges at the tip of these micrometric structures are responsible for the controlled adhesion of the insect on a large variety of substrates. The resulting adhesion force can exceed several times the body weight of the insect. The high aspect-ratio of setae suggests that flexibility is a key ingredient in this capillary-based adhesion mechanism. There is indeed a strong coupling between their elastic deformation and the shape of the liquid meniscus. In this experimental work, we observe and quantify the local deflection of dock beetle seta tips under perpendicular loading using interference microscopy. Our results are then interpreted in the light of an analytic model of elastocapillarity. This research has been funded by the FRIA/FNRS and the Interuniversity Attraction Poles Programme (IAP 7/38 MicroMAST) initiated by the Belgian Science Policy Office.

  11. Capillarity-based switchable adhesion.

    PubMed

    Vogel, Michael J; Steen, Paul H

    2010-02-23

    Drawing inspiration from the adhesion abilities of a leaf beetle found in nature, we have engineered a switchable adhesion device. The device combines two concepts: The surface tension force from a large number of small liquid bridges can be significant (capillarity-based adhesion) and these contacts can be quickly made or broken with electronic control (switchable). The device grabs or releases a substrate in a fraction of a second via a low-voltage pulse that drives electroosmotic flow. Energy consumption is minimal because both the grabbed and released states are stable equilibria that persist with no energy added to the system. Notably, the device maintains the integrity of an array of hundreds to thousands of distinct interfaces during active reconfiguration from droplets to bridges and back, despite the natural tendency of the liquid toward coalescence. We demonstrate the scaling of adhesion strength with the inverse of liquid contact size. This suggests that strengths approaching those of permanent bonding adhesives are possible as feature size is scaled down. In addition, controllability is fast and efficient because the attachment time and required voltage also scale down favorably. The device features compact size, no solid moving parts, and is made of common materials.

  12. Capillarity-based switchable adhesion

    PubMed Central

    Vogel, Michael J.; Steen, Paul H.

    2010-01-01

    Drawing inspiration from the adhesion abilities of a leaf beetle found in nature, we have engineered a switchable adhesion device. The device combines two concepts: The surface tension force from a large number of small liquid bridges can be significant (capillarity-based adhesion) and these contacts can be quickly made or broken with electronic control (switchable). The device grabs or releases a substrate in a fraction of a second via a low-voltage pulse that drives electroosmotic flow. Energy consumption is minimal because both the grabbed and released states are stable equilibria that persist with no energy added to the system. Notably, the device maintains the integrity of an array of hundreds to thousands of distinct interfaces during active reconfiguration from droplets to bridges and back, despite the natural tendency of the liquid toward coalescence. We demonstrate the scaling of adhesion strength with the inverse of liquid contact size. This suggests that strengths approaching those of permanent bonding adhesives are possible as feature size is scaled down. In addition, controllability is fast and efficient because the attachment time and required voltage also scale down favorably. The device features compact size, no solid moving parts, and is made of common materials. PMID:20133725

  13. High performance Cu adhesion coating

    SciTech Connect

    Lee, K.W.; Viehbeck, A.; Chen, W.R.; Ree, M.

    1996-12-31

    Poly(arylene ether benzimidazole) (PAEBI) is a high performance thermoplastic polymer with imidazole functional groups forming the polymer backbone structure. It is proposed that upon coating PAEBI onto a copper surface the imidazole groups of PAEBI form a bond with or chelate to the copper surface resulting in strong adhesion between the copper and polymer. Adhesion of PAEBI to other polymers such as poly(biphenyl dianhydride-p-phenylene diamine) (BPDA-PDA) polyimide is also quite good and stable. The resulting locus of failure as studied by XPS and IR indicates that PAEBI gives strong cohesive adhesion to copper. Due to its good adhesion and mechanical properties, PAEBI can be used in fabricating thin film semiconductor packages such as multichip module dielectric (MCM-D) structures. In these applications, a thin PAEBI coating is applied directly to a wiring layer for enhancing adhesion to both the copper wiring and the polymer dielectric surface. In addition, a thin layer of PAEBI can also function as a protection layer for the copper wiring, eliminating the need for Cr or Ni barrier metallurgies and thus significantly reducing the number of process steps.

  14. Predicted TeV Gamma-ray Spectra and Images of Shell Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Reynolds, S. P.

    1999-04-01

    One supernova remnant, SN 1006, is now known to produce synchrotron X-rays (Koyama et al., 1995, Nature, 378, 255), requiring 100 TeV electrons. SN 1006 has also been seen in TeV gamma rays (Tanimori et al., 1998, ApJ, 497, L25), almost certainly due to cosmic-microwave-background photons being upscattered by those same electrons. Other young supernova remnants should also produce high-energy electrons, even if their X-ray synchrotron emission is swamped by conventional thermal X-ray emission. Upper limits to the maximum energy of shock-accelerated electrons can be found for those remnants by requiring that their synchrotron spectrum steepen enough to fall below observed thermal X-rays (Reynolds and Keohane 1999, ApJ, submitted). For those upper-limit spectra, I present predicted TeV inverse-Compton spectra and images for assumed values of the mean remnant magnetic field. Ground-based TeV gamma-ray observations of remnants may be able to put even more severe limits on the presence of highly energetic electrons in remnants, raising problems for conventional theories of galactic cosmic-ray production in supernova remnants. Detections will immediately confirm that SN 1006 is not alone, and will give mean remnant magnetic field strengths.

  15. Pitavastatin versus Pravastatin in Reduction of Remnant Lipoprotein Cholesterol in Patients with Dyslipidemias.

    PubMed

    Roever, Leonardo

    2016-05-01

    Remnant lipoproteins cholesterol are products of partially catabolized chylomicrons and very-low-density lipoprotein, from which some triglycerides have been removed. These particles are smaller and are believed to be strongly atherogenic. Elevated Remnant lipoproteins cholesterol levels were reported to be associated with endothelial dysfunction and atherosclerotic disease.

  16. TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS

    SciTech Connect

    Tang, Xiaping; Chevalier, Roger A. E-mail: rac5x@virginia.edu

    2015-02-20

    Recent gamma-ray observations show that middle-aged supernova remnants (SNRs) interacting with molecular clouds can be sources of both GeV and TeV emission. Models involving reacceleration of preexisting cosmic rays (CRs) in the ambient medium and direct interaction between SNR and molecular clouds have been proposed to explain the observed gamma-ray emission. For the reacceleration process, standard diffusive shock acceleration (DSA) theory in the test particle limit produces a steady-state particle spectrum that is too flat compared to observations, which suggests that the high-energy part of the observed spectrum has not yet reached a steady state. We derive a time-dependent DSA solution in the test particle limit for situations involving reacceleration of preexisting CRs in the preshock medium. Simple estimates with our time-dependent DSA solution plus a molecular cloud interaction model can reproduce the overall shape of the spectra of IC 443 and W44 from GeV to TeV energies through pure π{sup 0}-decay emission. We allow for a power-law momentum dependence of the diffusion coefficient, finding that a power-law index of 0.5 is favored.

  17. Triggered star formation around the G54.1+0.3 supernova remnant

    NASA Astrophysics Data System (ADS)

    Koo, Bon-Chul; Kim, Hyun-Jeong; Moon, Dae-Sik; Kurtz, Stanley; McKee, Christopher F.

    G54.1+0.3 is a young, Crab-like supernova remnant (SNR) at a distance of 8 kpc. Recently, an infrared loop with embedded stellar sources surrounding the SNR was discovered by the Spitzer Space Telescope and the AKARI infrared telescope. The stellar sources are bright in the mid-infrared with significant excess emission. Koo et al. (2008) showed that the broadband near-infrared properties are consistent with OB stars at the same distance as the SNR, and concluded that they are young (≤2 Myr) stellar objects, whose formation was possibly triggered by the progenitor of G54.1+0.3. We present near-infrared (1-2.4 µm) spectra of six sources obtained with the TripleSpec spectrograph on the Palomar 5-m Hale telescope. Strong hydrogen and moderate He I absorption lines in the spectra confirm that the stellar sources are late-O and early-B stars, while no emission lines such as Br γ indicates the absence of circumstellar disks near the central stars, as Koo et al. suggested. We have also analyzed archival VLA data at 4, 6 and 20 cm, and present continuum images of the pulsar wind nebula and a surrounding shell. A spectral index analysis suggests the presence of free-free emission associated with the massive stars. We discuss the relation between the stellar sources, the infrared loop, and the SNR.

  18. Evidence of hadronic interaction in Tycho Supernova Remnant using Fermi-LAT data

    NASA Astrophysics Data System (ADS)

    Caragiulo, M.; Di Venere, L.

    2014-11-01

    The Fermi Large Area Telescope (LAT) has observed Tycho Supernova Remnant in the MeV-GeV energy range. The spectrum has been studied using the first three years of data and new data are being collected. We present a multiwavelength model of the observed spectrum from radio to TeV energy range, based on the hypothesis of hadronic origin of γ-rays. As described by the Fermi acceleration theory, a single proton population was considered, modeled with a simple power-law in momentum. The photon emissivity is computed following Kamae et al (2006) [T. Kamae, et al., ApJ 647 (2006) 692]. The leptonic component is also taken into account according to Giordano et al. (2012) [F. Giordano, et al., ApJ 744 (2012) L2] prescriptions and it turns out to be negligible with respect to the hadronic one. The model returns a spectral index of 2.23 (± 0.05) and an acceleration efficiency of 5% of the total kinetic energy expelled in Supernova explosion and it may provide a hint of the acceleration processes in SNRs up to energies close to the knee of cosmic ray spectrum. This work shows that experimental data can be easily explained with a simple model, representing a good test for the acceleration theory.

  19. SUZAKU OBSERVATIONS OF THE NON-THERMAL SUPERNOVA REMNANT HESS J1731-347

    SciTech Connect

    Bamba, Aya; Yamazaki, Ryo; Puehlhofer, Gerd; Klochkov, Dmitry; Acero, Fabio; Li Zhiyuan; Horns, Dieter; Kosack, Karl

    2012-09-10

    A detailed analysis of the non-thermal X-ray emission from the northwestern and southern parts of the supernova remnant (SNR) HESS J1731-347 with Suzaku is presented. The shell portions covered by the observations emit hard and lineless X-rays. The spectrum can be reproduced by a simple absorbed power-law model with a photon index {Gamma} of 1.8-2.7 and an absorption column density N{sub H} of (1.0-2.1) Multiplication-Sign 10{sup 22} cm{sup -2}. These quantities change significantly from region to region; the northwestern part of the SNR has the hardest and most absorbed spectrum. The western part of the X-ray shell has a smaller curvature than the northwestern and southern shell segments. A comparison of the X-ray morphology to the very high energy gamma-ray and radio images was performed. The efficiency of the electron acceleration and the emission mechanism in each portion of the shell are discussed. Thermal X-ray emission from the SNR was searched for but could not be detected at a significant level.

  20. Effect of the antiglucocorticoid RU-486 on glomerular hemodynamics in remnant nephrons.

    PubMed

    Cardoso, L R; Oliveira, A V; Santos, O F; Boim, M A; Razvickas, C V; Ajzen, H; Schor, N

    1997-01-01

    Endogenous glucocorticoid (GC) has been proposed to play a role in the adaptive functions of remnant nephron and participates in the progression of renal disease. The effect of GC blockade by RU-486 (20 mg/kg), an anti-GC agent, on the progression of chronic renal failure (CRF) was evaluated in Munich-Wistar rats. CRF was induced by 5/6 nephrectomy. Global renal function, glomerular hemodynamics, proteinuria and renal histopathology studies were performed after 60 days of CRF induction. RU administration in control or CRF groups did not induce significant changes in total renal function, mean arterial or intraglomerular hydraulic pressures, 24-hour proteinuria or sclerosis index. However, RU induced a significant reduction in single-nephron glomerular filtration rate in the superficial nephrons in both groups' control (decreases 20%) and CRF (decreases 57%), without changing total glomerular filtration rate, when compared with vehicle administration. These reductions were due to a decline in glomerular plasma flow rate (QA) and in glomerular ultrafiltration coefficient (Kf). These data suggest that GC played a role in the adaptive hyperfiltration associated with the compensatory mechanism but did not participate in the genesis of proteinuria or glomerulosclerosis in this experimental model. PMID:9208281

  1. HESS J1640-465 - an exceptionally luminous TeV γ-ray supernova remnant

    NASA Astrophysics Data System (ADS)

    Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Akhperjanian, A. G.; Angüner, E.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Bernlöhr, K.; Birsin, E.; Bissaldi, E.; Biteau, J.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Chalme-Calvet, R.; Chaves, R. C. G.; Cheesebrough, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Grondin, M.-H.; Grudzińska, M.; Häffner, S.; Hahn, J.; Harris, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Méhault, J.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Moderski, R.; Mohamed, M.; Moulin, E.; Murach, T.; Naumann, C. L.; de Naurois, M.; Niemiec, J.; Nolan, S. J.; Oakes, L.; Ohm, S.; Wilhelmi, E. de Oña; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Arribas, M. Paz; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; Reyes, R. de los; Rieger, F.; Rob, L.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sol, H.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Völk, H. J.; Volpe, F.; Vorster, M.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Zabalza, V.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2014-04-01

    The results of follow-up observations of the TeV γ-ray source HESS J1640-465 from 2004 to 2011 with the High Energy Stereoscopic System (HESS) are reported in this work. The spectrum is well described by an exponential cut-off power law with photon index Γ = 2.11 ± 0.09stat ± 0.10sys, and a cut-off energy of E_c = 6.0^{+2.0}_{-1.2} TeV. The TeV emission is significantly extended and overlaps with the northwestern part of the shell of the SNR G338.3-0.0. The new HESS results, a re-analysis of archival XMM-Newton data and multiwavelength observations suggest that a significant part of the γ-ray emission from HESS J1640-465 originates in the supernova remnant shell. In a hadronic scenario, as suggested by the smooth connection of the GeV and TeV spectra, the product of total proton energy and mean target density could be as high as WpnH ˜ 4 × 1052(d/10kpc)2 erg cm-3.

  2. A GeV Source in the Direction of Supernova Remnant CTB 37B

    NASA Astrophysics Data System (ADS)

    Xin, Yu-Liang; Liang, Yun-Feng; Li, Xiang; Yuan, Qiang; Liu, Si-Ming; Wei, Da-Ming

    2016-01-01

    Supernova remnants (SNRs) are the most attractive candidates for the acceleration sites of Galactic cosmic rays. We report the detection of GeV γ-ray emission with the Pass 8 events recorded by the Fermi Large Area Telescope (Fermi-LAT) in the vicinity of the shell-type SNR CTB 37B that is likely associated with the TeV γ-ray source HESS J1713–381. The photon spectrum of CTB 37B is consistent with a power law with an index of 1.89 ± 0.08 in the energy range of 0.5–500 GeV, and the measured flux connects smoothly with that of HESS J1713–381 at a few hundred GeV. No significant spatial extension and time variation are detected. The multi-wavelength data can be well fitted with either a leptonic model or a hadronic one. However, parameters of both models suggest more efficient particle acceleration than typical SNRs. Meanwhile, the X-ray and γ-ray spectral properties of CTB 37B show that it is an interesting source bridging young SNRs dominated by non-thermal emission and old SNRs interacting with molecular clouds.

  3. Detailed studies of shock-cloud interaction toward the young supernova remnants

    NASA Astrophysics Data System (ADS)

    Sano, H.; Fukui, Y.

    2016-06-01

    In young supernova remnants (SNRs; ˜2000 yrs), the study of the interaction between the shock waves and the inhomogeneous interstellar gas is a key element in understanding the SNR evolution, cosmic-ray acceleration, and multi-wavelength emission. In particular, TeV γ-ray and synchrotron X-ray bright SNRs, RX J1713.7-3946, RX J0852.0-4622, and N132D have been considered good candidates for an efficient cosmic-ray accelerator via shock-cloud interaction (Sano et al. 2013, 2015a; Fukui 2013). In RXJ1713, we performed imaging and spectral analysis of the Suzaku X-rays and compared it with the interstellar gas distribution (Sano et al. 2013; 2015b). The shock interaction with dense gas clumps enhances turbulence and magnetic fields up to mG around the clumps, which was observed as limb-brightening of the synchrotron X-rays and hard spectra with photon indexes of less than 2.4. Moreover, turbulence and magnetic field amplifications may promote an additional acceleration of cosmic-ray electrons. In contrast, the synchrotron X-rays also become bright toward diffuse gas regions due to the high shock velocity. In this talk, we introduce the recent results of shock-cloud interaction toward RX J1713.7-3946, RX J0852.0-4622, and N132D using the Suzaku, XMM-Newton, Chandra X-rays, and interstellar gas datasets.

  4. Suzaku Observations of the Non-thermal Supernova Remnant HESS J1731-347

    NASA Astrophysics Data System (ADS)

    Bamba, Aya; Pühlhofer, Gerd; Acero, Fabio; Klochkov, Dmitry; Tian, Wenwu; Yamazaki, Ryo; Li, Zhiyuan; Horns, Dieter; Kosack, Karl; Komin, Nukri

    2012-09-01

    A detailed analysis of the non-thermal X-ray emission from the northwestern and southern parts of the supernova remnant (SNR) HESS J1731-347 with Suzaku is presented. The shell portions covered by the observations emit hard and lineless X-rays. The spectrum can be reproduced by a simple absorbed power-law model with a photon index Γ of 1.8-2.7 and an absorption column density N H of (1.0-2.1) × 1022 cm-2. These quantities change significantly from region to region; the northwestern part of the SNR has the hardest and most absorbed spectrum. The western part of the X-ray shell has a smaller curvature than the northwestern and southern shell segments. A comparison of the X-ray morphology to the very high energy gamma-ray and radio images was performed. The efficiency of the electron acceleration and the emission mechanism in each portion of the shell are discussed. Thermal X-ray emission from the SNR was searched for but could not be detected at a significant level.

  5. Phosphorus in the young supernova remnant Cassiopeia A.

    PubMed

    Koo, Bon-Chul; Lee, Yong-Hyun; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

    2013-12-13

    Phosphorus ((31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ((56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion.

  6. Remnant group of local Lorentz transformations in f (T ) theories

    NASA Astrophysics Data System (ADS)

    Ferraro, Rafael; Fiorini, Franco

    2015-03-01

    It is shown that the extended teleparallel gravitational theories, known as f (T ) theories, inherit some on shell local Lorentz invariance associated with the tetrad field defining the spacetime structure. We discuss some enlightening examples, such as Minkowski spacetime and cosmological (Friedmann-Robertson-Walker and Bianchi type I) manifolds. In the first case, we show that the absence of gravity reveals itself as an incapability in the selection of a preferred parallelization at a local level, due to the fact that the infinitesimal local Lorentz subgroup acts as a symmetry group of the frame characterizing Minkowski spacetime. Finite transformations are also discussed in these examples and, contrary to the common lore on the subject, we conclude that the set of tetrads responsible for the parallelization of these manifolds is quite vast and that the remnant group of local Lorentz transformations includes one- and two-dimensional Abelian subgroups of the Lorentz group.

  7. ICPP: Collisionless shock and supernova remnant simulation experiments on VULCAN.

    NASA Astrophysics Data System (ADS)

    Woolsey, Nigel C.

    2000-10-01

    The VULCAN laser at the Central Laser Facility is used for laboratory-based simulations of collisionless shocks. One of the most difficult aspects of collisionless shock behaviour, the role of the magnetic field, is to be tested directly against experiment. Preliminary experiments to generate strong magnetic fields using a laser-driven mm-scale Helmholtz coil, and the formation of collisionless colliding plasmas using two counter-streaming exploding foil plasmas will be discussed. We consider the scaling of the hydrodynamics and magnetic field of the these experiments to those in supernova remnants (SNR) impacting the interstellar medium (ISM). This is achieved by ensuring the experiment and the SNR-ISM exhibit similar values of key dimensionless parameters. Work supported in part by EPSRC, CLF Direct Access, CEC-ERB FMR XCT 980168, Euratom and the UK DTI.

  8. Grain destruction in a supernova remnant shock wave

    SciTech Connect

    Raymond, John C.; Gaetz, Terrance J.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Sankrit, Ravi

    2013-12-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants (SNRs), gradually enriching the gas phase with refractory elements. We have measured emission in C IV λ1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus, these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the shock is too high compared with the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-shock medium limit our ability to test dust destruction models in detail.

  9. The neutron star born in the Antlia supernova remnant

    NASA Astrophysics Data System (ADS)

    Tetzlaff, N.; Torres, G.; Neuhäuser, R.; Hohle, M. M.

    2013-10-01

    Among all known young nearby neutron stars, we search for the neutron star that was born in the same supernova event that formed the Antlia supernova remnant (SNR). We also look for a runaway star that could have been the former companion to the neutron star (if it exists) and then got ejected due to the same supernova. We find the pulsar PSR J0630-2834 to be the best candidate for a common origin with the Antlia SNR. In that scenario, the SNR is ≈1.2 Myr old and is presently located at a distance of ≈138 pc. We consider the runaway star HIP 47155 a former companion candidate to PSR J0630-2834. The encounter time and place is consistent with both stars being ejected from the Antlia SNR. We measured the radial velocity of HIP 47155 as 32.42 ± 0.70 km s-1.

  10. What Are the Compact Central Objects in Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Graber, James

    2002-04-01

    Recent Chandra observations of the compact central objects in supernova remnants have shown puzzling results that do not seem to be consistent with either black holes or neutron stars. (See e.g. Pavlov, Sanwal, Garmire and Zavlin, astro-ph-0112322.) In particular, the inferred effective emitting surface is too small to be the entire surface of a neutron star, but too bright to be a black hole. We discuss the possibility that these compact objects might be red holes instead of black holes or neutron stars. Red holes, which occur in alternate theories of gravity, naturally predict both the greater brightness of the emissions and the smaller effective size of the emitting surface from a collapsed object of the appropriate mass.

  11. Type Ia supernova remnants: shaping by iron bullets

    NASA Astrophysics Data System (ADS)

    Tsebrenko, Danny; Soker, Noam

    2015-10-01

    Using 2D numerical hydrodynamical simulations of Type Ia supernova remnants (SNR Ia) we show that iron clumps few times denser than the rest of the SN ejecta might form protrusions in an otherwise spherical SNR. Such protrusions exist in some SNR Ia, e.g. SNR 1885 and Tycho. Iron clumps are expected to form in the deflagration to detonation explosion model. In SNR Ia where there are two opposite protrusions, termed `ears', such as Kepler's SNR and SNR G1.9+0.3, our scenario implies that the dense clumps, or iron bullets, were formed along an axis. Such a preferred axis can result from a rotating white dwarf progenitor. If our claim holds, this offers an important clue to the SN Ia explosion scenario.

  12. SN1987A: The Birth of a Supernova Remnant

    NASA Technical Reports Server (NTRS)

    McCray, Richard

    2003-01-01

    This grant was intended to support the development of theoretical models needed to interpret and understand the observations by the Hubble Space Telescope and the Chandra X-ray telescope of the rapidly developing remnant of Supernova 1987A. In addition, we carried out a few investigations of related topics. The project was spectacularly successful. The models that we developed provide the definitive framework for predicting and interpreting this phenomenon. Following is a list of publications based on our work. Some of these papers include results of both theoretical modeling supported by this project and also analysis of data supported by the Space Telescope Science Institute and the Chandra X-ray Observatory. We first list papers published in refereed journals, then conference proceedings and book chapters, and also an educational web site.

  13. Remnant Pacemaker Lead Tips after Lead Extractions in Pacemaker Infections

    PubMed Central

    Kim, Daehoon; Baek, Yong-Soo; Lee, Misol; Uhm, Jae-Sun; Pak, Hui-Nam; Lee, Moon-Hyoung

    2016-01-01

    Complete hardware removal is recommended in the case of patients with cardiovascular implantable electronic device (CIED) infections. However, the complete extraction of chronically implanted leads is not always achieved. The outcomes and optimal management of CIED infections with retained material after lead extractions have not been elucidated. In this case report, we present five patients with CIED infections with remnant lead tips even after lead extractions. Two patients had localized pocket infections, and were managed with antibiotics for a period of more than two weeks. The other three patients had infective endocarditis, and were managed with antibiotics for a period of more than four weeks. In one patient, the lead tip migrated to the right pulmonary artery, but did not produce any symptoms or complications. Only one of five patients experienced a resurgence of an infection. PMID:27482268

  14. Grain Destruction in a Supernova Remnant Shock Wave

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi

    2014-01-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV (lambda)1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the shock is too high compared to the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- shock medium limit our ability to test dust destruction models in detail.

  15. Intermediate-age globular clusters in four galaxy merger remnants

    SciTech Connect

    Trancho, Gelys; Miller, Bryan W.; Schweizer, François; Burdett, Daniel P.; Palamara, David

    2014-08-01

    We present the results of combining Hubble Space Telescope optical photometry with ground-based K{sub s} -band photometry from the Gemini imagers NIRI and FLAMINGOS-I to study the globular cluster (GC) populations in four early-type galaxies that are candidate remnants of recent mergers (NGC 1700, NGC 2865, NGC 4382, and NGC 7727). These galaxies were chosen based on their blue colors and fine structure, such as shells and ripples that are indicative of past interactions. We fit the combined VIK{sub s} GC data with simple toy models of mixed cluster populations that contain three subpopulations of different age and metallicity. The fits, done via chi-squared mapping of the parameter space, yield clear evidence for the presence of intermediate-age clusters in each galaxy. We find that the ages of ∼1-2 Gyr for these GC subpopulations are consistent with the previously estimated merger ages for the host galaxies.

  16. NGC 2419-Another Remnant of Accretion by the Milky Way

    NASA Astrophysics Data System (ADS)

    Cohen, Judith G.; Kirby, Evan N.; Simon, Joshua D.; Geha, Marla

    2010-12-01

    We isolate a sample of 43 upper red giant branch stars in the extreme outer halo Galactic globular cluster (GC) NGC 2419 from two Keck/DEIMOS slitmasks. The probability that there is more than one contaminating halo field star in this sample is extremely low. Analysis of moderate-resolution spectra of these cluster members, as well as of our Keck/HIRES high-resolution spectra of a subsample of them, demonstrates that there is a small but real spread in Ca abundance of ~0.2 dex within this massive metal-poor GC. This provides additional support to earlier suggestions that NGC 2419 is the remnant of a dwarf galaxy accreted long ago by the Milky Way. Based in part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.

  17. High-Resolution Polarimetry of Supernova Remnant Kesteven 69

    NASA Astrophysics Data System (ADS)

    Wood, C. A.; Mufson, S. L.; Dickel, J. R.

    2008-06-01

    Reported here are high-resolution 6 cm measurements of the adolescent supernova remnant (SNR) Kesteven 69 made with the hybrid BnC configuration of the Very Large Array. Several three-field mosaics of the polarized and total intensity have been used to study this SNR. These investigations lead to a coherent picture of this region. The expanding shock defines an outer rim of high total intensity, suggesting the front is running into large dense clouds with random magnetic field directions. The SNR consists of predominantly of two types of regions, those with high total and relatively weak polarized emission and those with relatively weak total and strong polarized emission. This morphology can be generally explained by the number of clouds with organized magnetic field along the line of sight. Within this SNR there are regions where the field is varying from radial to tangential. As the SN shock encounters clouds, magnetic fields within clouds will strongly affect cloud dynamics.

  18. Observations of supernova remnants with the Sardinia Radio Telescope

    NASA Astrophysics Data System (ADS)

    Egron, E.; Pellizzoni, A.; Loru, S.; Iacolina, M. N.; Marongiu, M.; Righini, S.; Mulas, S.; Murtas, G.; Bachetti, M.; Concu, R.; Melis, A.; Trois, A.; Ricci, R.; Pilia, M.

    2016-06-01

    In the frame of the Astronomical Validation activities for the 64m Sardinia Radio Telescope, we performed 5-22 GHz imaging observations of the complex-morphology supernova remnants (SNRs) W44 and IC443. We adopted innovative observing and mapping techniques providing unprecedented accuracy for single-dish imaging of SNRs at these frequencies, revealing morphological details typically available only at lower frequencies through interferometry observations. High-frequency studies of SNRs in the radio range are useful to better characterize the spatially-resolved spectra and the physical parameters of different regions of the SNRs interacting with the ISM. Furthermore, synchrotron-emitting electrons in the high-frequency radio band are also responsible for the observed high-energy phenomenology as -e.g.- Inverse Compton and bremsstrahlung emission components observed in gamma-rays, to be disentangled from hadron emission contribution (providing constraints on the origin of cosmic rays).

  19. Intermediate-age Globular Clusters in Four Galaxy Merger Remnants

    NASA Astrophysics Data System (ADS)

    Trancho, Gelys; Miller, Bryan W.; Schweizer, François; Burdett, Daniel P.; Palamara, David

    2014-08-01

    We present the results of combining Hubble Space Telescope optical photometry with ground-based Ks -band photometry from the Gemini imagers NIRI and FLAMINGOS-I to study the globular cluster (GC) populations in four early-type galaxies that are candidate remnants of recent mergers (NGC 1700, NGC 2865, NGC 4382, and NGC 7727). These galaxies were chosen based on their blue colors and fine structure, such as shells and ripples that are indicative of past interactions. We fit the combined VIKs GC data with simple toy models of mixed cluster populations that contain three subpopulations of different age and metallicity. The fits, done via chi-squared mapping of the parameter space, yield clear evidence for the presence of intermediate-age clusters in each galaxy. We find that the ages of ~1-2 Gyr for these GC subpopulations are consistent with the previously estimated merger ages for the host galaxies.

  20. 1. Remnants of the last lock on the George Washington ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Remnants of the last lock on the George Washington 'Potowmack Canal, just before the barge entered the Potomac River. The latter can be seen through the foliage of the tree which has grown up in the old canal bed. On the left hand side of the photograph, not shown here in its entirety, are the old iron studdings which held the gates, to permit the barges to pass easily into the river. On the right hand side of the photograph is shown the crumbling remains of the lock with their receased oval space clearly shown, into which the lock gate retrieved when the barge was lowered to the next level. The depth from the spot where the individual is shown pointing to the top of the lock, is about 24 or 25 ft., and the canal has been filled up with broken ... - Potowmack Company: Great Falls Canal, Locks No. 3, 4, 5, Great Falls, Fairfax County, VA

  1. The first few months of a supernova remnant

    NASA Astrophysics Data System (ADS)

    Gabler, M.; Janka, H.-T.; Wongwathanara, A.

    2016-06-01

    We perform long-term, hydrodynamical simulations of supernova remnants in 3 dimensions. Continuing the simulations of A.Wongwathanarat "3D long-time CCSN simulations: from shock revival to shock break-out" we follow the evolution of the shock and the ejecta during the first few months after the explosion. The explosion is simulated with a ray-by-ray gray neutrino transport approximation and the so called Yin-Yang grid (an axis-free spherical polar coordinates grid). For the late phases we investigate here, the neutrino transport is no longer needed. We study the rising bubbles of the ejecta and follow how their morphology changes due to acceleration at the stellar surface. We further include the energy input caused by the decay of nickel and can identify the first traces of the influence of this radioactive heating. The bubbles, which otherwise would expand homologously, start to inflate due to the additional energy source of the nickel decay.

  2. Phosphorus in the young supernova remnant Cassiopeia A.

    PubMed

    Koo, Bon-Chul; Lee, Yong-Hyun; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

    2013-12-13

    Phosphorus ((31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ((56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion. PMID:24337291

  3. Shock Velocity Variations in Supernova Remnant Simulation Experiments

    NASA Astrophysics Data System (ADS)

    Drake, R. P.; Carroll, J. J., III; Smith, T. B.; Reisig, H. N.; Glendinning, S. G.; Estabrook, K.; Remington, B. A.; Wallace, R.; McCray, R.

    1998-11-01

    We are studying the hydrodynamic behavior of a laboratory system that is a good scaled model of young supernova remnants. The hydrodynamic effects are driven by a supersonic flow, produced by the Nova laser. It does this by driving a strong shock, produced by x-ray ablation, out the back of a plastic slab. The ejecta expand, accelerate, cool, and then impact a low-density foam. There the ejecta stagnate and form a reverse shock while driving a strong shock forward through the foam. We observe this hydrodynamic assembly by x-ray radiography. The shock velocities in one case agree with those found by a computer simulation, while in another case they do not. We will report our investigation of this discrepancy. (Work supported by the US Department of Energy under LLNL LDRD-ER Grant No. 97-ERD-022 and by the University of Michigan.)

  4. Spitzer Space Telescope Spectroscopy of the Kepler Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Roellig, T. L.; Onaka, T.

    2004-01-01

    The Infrared Spectrograph on the Spitzer Space Telescope was used for observations of the Kepler supernova remnant, with all four instrument modules targeted on the bright infrared knot located at 17h30m35.80s,-21d28m54.0s (J2000). The low spectral resolution modules data show a dust continuum spectrum consistent with dust grains heated by high-energy electrons, while the high resolution modules data show atomic emission line ratios consistent with excitation by a high velocity shock of greater than 100 kilometers per second and electron densities of approximately 1,000 per centimeter. The abundance ratios for the six detected elements show signs of heavy-element enhancement. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology. Support for this work was provided by NASA's Office of Space Science.

  5. Interfacial adhesion: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Bozzolo, Guillermo H.; Finley, Clarence W.; Banerjea, Amitava

    1988-01-01

    Adhesion, the binding of different materials at an interface, is of general interest to many branches of technology, e.g., microelectronics, tribology, manufacturing, construction, etc. However, there is a lack of fundamental understanding of such diverse interfaces. In addition, experimental techniques generally have practical objectives, such as the achievement of sufficient strength to sustain mechanical or thermal effects and/or have the proper electronic properties. In addition, the theoretical description of binding at interfaces is quite limited, and a proper data base for such theoretical analysis does not exist. This presentation will review both experimental and theoretical aspects of adhesion in nonpolymer materials. The objective will be to delineate the critical parameters needed, governing adhesion testing along with an outline of testing objectives. A distinction will be made between practical and fundamental objectives. Examples are given where interfacial bonding may govern experimental consideration. The present status of theory is presented along wiith recommendations for future progress and needs.

  6. Interfacial adhesion - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Banerjea, Amitava; Bozzolo, Guillermo H.; Finley, Clarence W.

    1988-01-01

    Adhesion, the binding of different materials at an interface, is of general interest to many branches of technology, e.g., microelectronics, tribology, manufacturing, construction, etc. However, there is a lack of fundamental understanding of such diverse interfaces. In addition, experimental techniques generally have practical objectives, such as the achievement of sufficient strength to sustain mechanical or thermal effects and/or have the proper electronic properties. In addition, the theoretical description of binding at interfaces is quite limited, and a proper data base for such theoretical analysis does not exist. This presentation will review both experimental and theoretical aspects of adhesion in nonpolymer materials. The objective will be to delineate the critical parameters needed, governing adhesion testing along with an outline of testing objectives. A distinction will be made between practical and fundamental objectives. Examples are given where interfacial bonding may govern experimental consideration. The present status of theory is presented along with recommendations for future progress and needs.

  7. Platelet adhesiveness after blood donation.

    PubMed

    Pegrum, G D; Harrison, K M; Shaw, S

    1971-03-13

    Platelet adhesiveness to glass was measured in healthy blood donors at the time of and eight days after donating 500 ml of blood. By a whole blood method a highly significant increase was found whereas by a method using platelet-rich plasma with added adenosine diphosphate there was only a slightly significant increase. The discrepancy suggested that changes in the red cell population might influence the results. Packed red cells from 19 blood donors obtained at the time of donation and eight days later were mixed with fresh pooled platelets from the same independent persons on each occasion. The whole blood platelet adhesiveness on this mixture showed an increase in every case after blood donation. It is postulated that the increased adhesiveness is influenced by the presence of young red cells.

  8. UV curable pressure sensitive adhesives

    SciTech Connect

    Glotfelter, C.A.

    1995-12-01

    Pressure sensitive adhesives (PSA`s) have become a ubiquitous element in our society, so much so, that the relative status of a society can be determined by the per capita consumption of PSA`s. We discuss new monomers as components of PSA formulations which enable adhesion to be achieved on a variety of substrates. Since solventless coating systems are desirable, the UV PSA market is of utmost importance to meeting the strict environmental guidelines now being imposed worldwide. In addition, highly ethoxylated monomers have shown promise in water dispersed PSA formulations, and a self-emulsifying acrylate monomer has been developed to offer dispersive abilities without using traditional emulsifying agents. This talk will focus on the effects of the materials described on properties of adhesive strength and shear strength in UV PSA formulations.

  9. Adhesive capsulitis: a case report

    PubMed Central

    Kazemi, Mohsen

    2000-01-01

    Adhesive capsulitis or frozen shoulder is an uncommon entity in athletes. However, it is a common cause of shoulder pain and disability in the general population. Although it is a self limiting ailment, its rather long, restrictive and painful course forces the affected person to seek treatment. Conservative management remains the mainstay treatment of adhesive capsulitis. This includes chiropractic manipulation of the shoulder, therapeutic modalities, mobilization, exercise, soft tissue therapy, nonsteroidal anti-inflammatory drugs, and steroid injections. Manipulation under anesthesia is advocated when the conservative treatment fails. A case of secondary adhesive capsulitis in a forty-seven-year-old female recreational squash player is presented to illustrate clinical presentation, diagnosis, radiographic assessment and conservative chiropractic management. The patient’s shoulder range of motion was full and pain free with four months of conservative chiropractic care. ImagesFigure 1Figure 2Figure 3

  10. A novel addition polyimide adhesive

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Progar, D. J.

    1981-01-01

    An addition polyimide adhesive, LARC 13, was developed which shows promise for bonding both titanium and composites for applications which require service temperatures in excess of 533 K. The LARC 13 is based on an oligomeric bis nadimide containing a meta linked aromatic diamine. The adhesive melts prior to polymerization due to its oligomeric nature, thereby allowing it to be processed at 344 kPa or less. Therefore, LARC 13 is ideal for the bonding of honeycomb sandwich structures. After melting, the resin thermosets during the cure of the nadic endcaps to a highly crosslinked system. Few volatiles are evolved, thus allowing large enclosed structures to be bonded. Preparation of the adhesive as well as bonding, aging, and testing of lap shear and honeycomb samples are discussed.

  11. Supernova remnant W49B and its environment

    SciTech Connect

    Zhu, H.; Tian, W. W.; Zuo, P. E-mail: tww@bao.ac.cn

    2014-10-01

    We study gamma-ray supernova remnant (SNR) W49B and its environment using recent radio and infrared data. Spitzer Infrared Spectrograph low resolution data of W49B shows shocked excitation lines of H{sub 2} (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H{sub 2} gas is composed of two components with temperatures of ∼260 K and ∼1060 K, respectively. Various spectral lines from atomic and ionic particles are detected toward W49B. We suggest that the ionic phase has an electron density of ∼500 cm{sup –3} and a temperature of ∼10{sup 4} K by the spectral line diagnoses. The mid- and far-infrared data from MSX, Spitzer, and Herschel reveal a 151 ± 20 K hot dust component with a mass of 7.5 ± 6.6 × 10{sup –4} M {sub ☉} and a 45 ± 4 K warm dust component with a mass of 6.4 ± 3.2 M {sub ☉}. The hot dust is likely from materials swept up by the shock of W49B. The warm dust may possibly originate from the evaporation of clouds interacting with W49B. We build the H I absorption spectra of W49B and four nearby H II regions (W49A, G42.90+0.58, G42.43-0.26, and G43.19-0.53) and study the relation between W49B and the surrounding molecular clouds by employing the 2.12 μm infrared and CO data. We therefore obtain a kinematic distance of ∼10 kpc for W49B and suggest that the remnant is likely associated with the CO cloud at about 40 km s{sup –1}.

  12. ALEXIS Observations of the Monogem Ring Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Plucinsky, Paul; West, Donald (Technical Monitor)

    2001-01-01

    The subject grant is for the analysis of ALEXIS observations of the Monogem Ring supernova remnant using the diffuse all-sky maps produced from the ALEXIS all-sky survey. The work is to produce ratio maps of the three energy bands provided by ALEXIS, analyze the ratio data to constrain the intervening neutral hydrogen column density and the temperature and elemental abundances of the X-ray emitting gas, compare the structure to that observed in the ROSAT maps, and incorporate the results into current supenova remnant evolution models. The work outlined above has been significantly delayed since the ALEXIS diffuse all-sky maps took longer to produce than anticipated. Unfortunately, the ALEXIS satellite suffered a failure of the Pegasus launch vehicle which left the satellite in a partially functioning condition. The attitude control system of the spacecraft was unable to operate as planned and this has greatly increased the complexity of the aspect solution. Our colleagues at Los Alamos have made progress in producing these maps and are nearing completion of the final maps. However, the quality of the data have been significantly compromised by the overall lower exposure due to the spacecraft problems and the higher background of the micro-channel plate detectors. We have compared the ALEXIS and ROSAT maps of this region of the sky and there is no obvious signal in the ALEXIS maps of the Monogem Ring. We are now exploring correlation techniques to determine if there is indeed a faint signal in the ALEXIS maps. Although, the project has been a disappointment so far, the data may still provide a valuable lower limit on the neutral hydrogen column density. This is a far cry from our original intentions, but would still be valuable science. Given the large delays in producing the ALEXIS sky maps, this work will continue past the end of the grant period.

  13. POPULATION III STARS AND REMNANTS IN HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Xu Hao; Norman, Michael L.; Wise, John H. E-mail: mlnorman@ucsd.edu

    2013-08-20

    Recent simulations of Population III star formation have suggested that some fraction form in binary systems, in addition to having a characteristic mass of tens of solar masses. The deaths of metal-free stars result in the initial chemical enrichment of the universe and the production of the first stellar-mass black holes. Here we present a cosmological adaptive mesh refinement simulation of an overdense region that forms a few 10{sup 9} M{sub Sun} dark matter halos and over 13,000 Population III stars by redshift 15. We find that most halos do not form Population III stars until they reach M{sub vir} {approx} 10{sup 7} M{sub Sun} because this biased region is quickly enriched from both Population III and galaxies, which also produce high levels of ultraviolet radiation that suppress H{sub 2} formation. Nevertheless, Population III stars continue to form, albeit in more massive halos, at a rate of {approx}10{sup -4} M{sub Sun} yr{sup -1} Mpc{sup -3} at redshift 15. The most massive starless halo has a mass of 7 Multiplication-Sign 10{sup 7} M{sub Sun }, which could host massive black hole formation through the direct gaseous collapse scenario. We show that the multiplicity of the Population III remnants grows with halo mass above 10{sup 8} M{sub Sun }, culminating in 50 remnants located in 10{sup 9} M{sub Sun} halos on average. This has implications that high-mass X-ray binaries and intermediate-mass black holes that originate from metal-free stars may be abundant in high-redshift galaxies.

  14. Hubble Space Telescope Image, Supernova Remnant Cassiopeia A

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The colorful streamers that float across the sky in this photo taken by NASA's Hubble Space Telescope (HST) were created by the universe's biggest firecracker, the titanic supernova explosion of a massive star. The light from the exploding star reached Earth 320 years ago, nearly a century before the United States celebrated its birth with a bang. The dead star's shredded remains are called Cassiopeia A, or 'Cas A' for short. Cas A is the youngest known supernova remnant in our Milky Way Galaxy and resides 10,000 light-years away in the constellation Cassiopeia, so the star actually blew up 10,000 years before the light reached Earth in the late 1600s. This HST image of Cas A shows for the first time that the debris is arranged into thousands of small, cooling knots of gas. This material eventually will be recycled into building new generations of stars and planets. Our own Sun and planets are constructed from the debris of supernovae that exploded billions of years ago. This photo shows the upper rim of the super nova remnant's expanding shell. Near the top of the image are dozens of tiny clumps of matter. Each small clump, originally just a small fragment of the star, is tens of times larger than the diameter of our solar system. The colors highlight parts of the debris where chemical elements are glowing. The dark blue fragments, for example, are richest in oxygen; the red material is rich in sulfur. The images were taken with the Wide Field and Planetary Camera 2 in January 2000 and January 2002. Image Credit: NASA and HST team (Stoics/AURA). Acknowledgment: R. Fesen (Darmouth) and J. Morse ( Univ. of Colorado).

  15. Supernova Remnants in the Most Fertile Galaxy: NGC 6946

    NASA Astrophysics Data System (ADS)

    Winkler, P. Frank; Long, Knox S.; Blair, William P.

    2014-08-01

    As the host to more recorded supernovae (nine in the past century) than any other galaxy, ngal is a unique venue for studying young (and old) supernova remnants (SNRs). Using deep emission-line images of ngal we obtained from WIYN, we have identified 148 new emission nebulae through their high S II:Hα ratios, indicating that they are strong SNR candidates. This is over 5 times as many as have previously been identified; yet of the 175 total objects, only 6 have been spectroscopically confirmed. We propose multislit spectroscopy from GMOS-N to study the majority of those with no spectra to date. Some 26 are essentially unresolved in our images (diameters ≲ 1 arcsec=27 pc at ngal) and hence probably are relatively young. Several are also coincident with soft X-ray sources (a further indicator of youthful vigor) and have strong O III emission. Some may be rare, ejecta- dominated core-collapse SNRs akin to Cas A, where ``fresh" nucleosynthesis products can be seen. Only spectroscopy, to look for broad emission lines from fast-moving ejecta, can confirm this. We will include spectra of two of the nine recorded SNe in ngal-the first late-time spectrum of SN 2004et, and the first of SN 1980K with high signal-to-noise-adding to the extremely small number of spectra for SNRs only a few decades old. Finally we will use the H II:Hα ratio in a large number of ISM-dominated SNRs to map the N abundance and its gradient across the disk of ngal, and we will use archival HST images to identify the stellar environments that produced the SNe whose remnants we see today.

  16. Low radio frequency observations and spectral modelling of the remnant of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    Callingham, J. R.; Gaensler, B. M.; Zanardo, G.; Staveley-Smith, L.; Hancock, P. J.; Hurley-Walker, N.; Bell, M. E.; Dwarakanath, K. S.; Franzen, T. M. O.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A.; For, B.-Q.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A. R.; Procopio, P.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2016-10-01

    We present Murchison Widefield Array observations of the supernova remnant (SNR) 1987A between 72 and 230 MHz, representing the lowest frequency observations of the source to date. This large lever arm in frequency space constrains the properties of the circumstellar medium created by the progenitor of SNR 1987A when it was in its red supergiant phase. As of late 2013, the radio spectrum of SNR 1987A between 72 MHz and 8.64 GHz does not show any deviation from a non-thermal power law with a spectral index of -0.74 ± 0.02. This spectral index is consistent with that derived at higher frequencies, beneath 100 GHz, and with a shock in its adiabatic phase. A spectral turnover due to free-free absorption by the circumstellar medium has to occur below 72 MHz, which places upper limits on the optical depth of ≤0.1 at a reference frequency of 72 MHz, emission measure of ≲13 000 cm-6 pc, and an electron density of ≲110 cm-3. This upper limit on the electron density is consistent with the detection of prompt radio emission and models of the X-ray emission from the supernova. The electron density upper limit implies that some hydrodynamic simulations derived a red supergiant mass-loss rate that is too high, or a wind velocity that is too low. The mass-loss rate of ˜5 × 10-6 M⊙ yr-1 and wind velocity of 10 km s-1 obtained from optical observations are consistent with our upper limits, predicting a current turnover frequency due to free-free absorption between 5 and 60 MHz.

  17. A 3-dimensional Analysis of the Cassiopeia A Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Isensee, Karl

    We present a multi-wavelength study of the nearby supernova remnant Cassiopeia A (Cas A). Easily resolvable supernova remnants such as Cas A provide a unique opportunity to test supernova explosion models. Additionally, we can observe key processes in the interstellar medium as the ejecta from the initial explosion encounter Cas A's powerful shocks. In order to accomplish these science goals, we used the Spitzer Space Telescope's Infrared Spectrograph to create a high resolution spectral map of select regions of Cas A, allowing us to make a Doppler reconstruction of its 3-dimensional structure structure. In the center of the remnant, we find relatively pristine ejecta that have not yet reached Cas A's reverse shock or interacted with the circumstellar environment. We observe O, Si, and S emission. These ejecta can form both sheet-like structures as well as filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in some regions, and separated by >500 km s -1 in others. Observed ejecta traveling toward us are, on average, ˜800 km s -1 slower than the material traveling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the emission interior to Cas A's reverse shock. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cassiopeia A will begin brightening in ∼30 years, and the front surface in ˜100 years. We then used similar observations from 3 regions on Cas A's reverse shock in order to create more 3-dimensional maps. In these regions, we observe supernova ejecta both immediately before and during the shock-ejecta interaction. We determine that the

  18. Adhesive, elastomeric gel impregnating composition

    DOEpatents

    Shaw, David Glenn; Pollard, John Randolph; Brooks, Robert Aubrey

    2002-01-01

    An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

  19. Dual-Mode Adhesive Pad

    NASA Technical Reports Server (NTRS)

    Hartz, Leslie

    1994-01-01

    Tool helps worker grip and move along large, smooth structure with no handgrips or footholds. Adheres to surface but easily released by actuating simple mechanism. Includes handle and segmented contact-adhesive pad. Bulk of pad made of soft plastic foam conforming to surface of structure. Each segment reinforced with rib. In sticking mode, ribs braced by side catches. In peeling mode, side catches retracted, and segmented adhesive pad loses its stiffness. Modified versions useful in inspecting hulls of ships and scaling walls in rescue operations.

  20. Protein adhesion force dynamics and single adhesion events.

    PubMed Central

    Sagvolden, G

    1999-01-01

    Using the manipulation force microscope, a novel atomic force microscope, the adhesion forces of bovine serum albumin, myoglobin, ferritin, and lysozyme proteins to glass and polystyrene substrates were characterized by following the force necessary to displace an adsorbed protein-covered microsphere over several orders of magnitude in time. This force was consistent with a power law with exponent a = 0.37 +/- 0.03 on polystyrene, indicating that there is no typical time scale for adhesion on this substrate. On glass, the rate of adhesion depended strongly on protein charge. Forces corresponding to single protein adhesion events were identified. The typical rupture force of a single lysozyme, ferritin, bovine serum albumin, and myoglobin protein adhering to glass was estimated to be 90 +/- 10 pN, 115 +/- 13 pN, 277 +/- 44 pN, and 277 +/- 44 pN, respectively, using a model of the experimental system. These forces, as well as the force amplitudes on hydrophobic polystyrene, correlate with protein stiffness. PMID:10388777

  1. The supernova remnant W50: understanding the magnetic fields in a unique outflow-driven object

    NASA Astrophysics Data System (ADS)

    Farnes, J. S.; Gaensler, B. M.

    We present new radio observations of the nebula W50 (G39.7-2.0), using the Australia Telescope Compact Array (ATCA). Our understanding of this enigmatic object has previously been hindered by the large angular extent of the nebulae (2x1 degrees), with the Western edge dipping into the Galactic plane. Such large objects are typically poorly studied due to the considerable number of separate pointings required for full imaging. The nebula is also entirely unique in that it appears to be interacting with the central compact source and first known Galactic microquasar, SS433. Our mosaiced, spectropolarimetric ATCA observations of this field are centred at 2.1 GHz, using a large bandwidth of 2 GHz. This allows us to measure the polarised fraction, rotation measure, depolarisation, and spectral index of W50's emission, and to detect diffuse linearly polarised emission which 'lights up' the large-scale ordered magnetic fields in the object. The challenge of processing such wide-field, wide-band, spectropolarimetric observations is a significant technical issue that is currently being faced by the upcoming Square Kilometre Array (SKA) pathfinders and will be faced by the SKA itself. We therefore analyse the data using techniques that are fundamental to understanding cosmic magnetism - such as Rotation Measure Synthesis - and that allow us to probe Faraday rotation along the line of sight towards W50. Through these methods it is possible to distinguish between magnetic effects arising in the nebula itself, and those arising along the line of sight in intervening Faraday screens. While W50 is typically considered to be a supernova remnant, the contribution from the initial explosion that presumably preceded formation of the compact object SS433, has not previously been convincingly distinguished from the impact of the jet and wind activity of the central system. We shall discuss how we are able to put constraints on the formation of the object through our discovery of a

  2. Indexing Consistency and Quality.

    ERIC Educational Resources Information Center

    Zunde, Pranas; Dexter, Margaret E.

    A measure of indexing consistency is developed based on the concept of 'fuzzy sets'. It assigns a higher consistency value if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on indexing consistency…

  3. [FTIR spectroscopic studies of facial prosthetic adhesives].

    PubMed

    Kang, Biao; Yang, Qing-fang; Liang, Jian-feng; Zhao, Yi-min

    2008-10-01

    According to the composition of the traditional facial prosthetic adhesives, most of adhesives can be classified into two categories: acrylic polymer-based adhesive and silicone-based adhesive. In previous studies, measurements of various mechanical bond strengths were carried out, whereas the functional groups of the adhesives were evaluated seldom during the adhesion. In the present study the analysis of two facial prosthetic adhesives (Epithane and Secure Adhesive) was carried out by using infrared spectroscopy. Two adhesives in the form of fluid or semisolid were submitted to FTIR spectroscopy, respectively. The results showed that water and ammonia residue volatilized during the solidification of Epithane, and absorption peak reduction of carbonyl was due to the volatilization of acetate vinyl from Secure Adhesive. Similar silicone functional groups both in the silicone-based adhesive and in silicone elastomer could be the key to higher bond strength between silicone elastomer and skin with silicone-based adhesive. The position, shape of main absorption peaks of three adhesives didn't change, which showing that their main chemicals and basic structures didn't change during solidification. PMID:19123392

  4. New adhesive withstands temperature extremes

    NASA Technical Reports Server (NTRS)

    Park, J. J.; Seidenberg, B.

    1978-01-01

    Adhesive, developed for high-temperature components aboard satellites, is useful at both high and low temperatures and exhibits low-vacuum volatility and low shrinkage. System uses polyfunctional epoxy with high aromatic content, low equivalent weight, and more compact polymer than conventional bisphenol A tape.

  5. Candida biofilms: is adhesion sexy?

    PubMed

    Soll, David R

    2008-08-26

    The development of Candida albicans biofilms requires two types of adhesion molecule - the Als proteins and Hwp1. Mutational analyses have recently revealed that these molecules play complementary roles, and their characteristics suggest that they may have evolved from primitive mating agglutinins.

  6. Candida biofilms: is adhesion sexy?

    PubMed

    Soll, David R

    2008-08-26

    The development of Candida albicans biofilms requires two types of adhesion molecule - the Als proteins and Hwp1. Mutational analyses have recently revealed that these molecules play complementary roles, and their characteristics suggest that they may have evolved from primitive mating agglutinins. PMID:18727911

  7. Photoresist substrate having robust adhesion

    DOEpatents

    Dentinger, Paul M.

    2005-07-26

    A substrate material for LIGA applications w hose general composition is Ti/Cu/Ti/SiO.sub.2. The SiO.sub.2 is preferably applied to the Ti/Cu/Ti wafer as a sputtered coating, typically about 100 nm thick. This substrate composition provides improved adhesion for epoxy-based photoresist materials, and particularly the photoresist material SU-8.

  8. Unfolding Grammars in Adhesive Categories

    NASA Astrophysics Data System (ADS)

    Baldan, Paolo; Corradini, Andrea; Heindel, Tobias; König, Barbara; Sobociński, Paweł

    We generalize the unfolding semantics, previously developed for concrete formalisms such as Petri nets and graph grammars, to the abstract setting of (single pushout) rewriting over adhesive categories. The unfolding construction is characterized as a coreflection, i.e. the unfolding functor arises as the right adjoint to the embedding of the category of occurrence grammars into the category of grammars.

  9. Fluorescence Reveals Contamination From Adhesives

    NASA Technical Reports Server (NTRS)

    Nikolia, William

    1992-01-01

    Contamination of nearby surfaces from ingredients in some adhesive materials detected by ultraviolet illumination and observation of resulting fluorescence. Identification of contaminants via telltale fluorescence not new; rather, significance lies in method of implementation and potential extension to wider variety of materials and applications.

  10. Computational Chemistry of Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Phillips, Donald H.

    1999-01-01

    This investigation is intended to determine the electrical mechanical, and chemical properties of adhesive bonds at the molecular level. The initial determinations will be followed by investigations of the effects of environmental effects on the chemistry and properties of the bond layer.

  11. Tackifier Dispersions to Make Pressure Sensitive Adhesives

    SciTech Connect

    2003-02-01

    Development of new processes for tackifier dispersion could improve the production of pressure sensitive adhesives. Pressure sensitive adhesives (PSAs) have the ability to adhere to different surfaces with manual or finger pressure.

  12. Importance of riparian remnants for frog species diversity in a highly fragmented rainforest

    PubMed Central

    Rodríguez-Mendoza, Clara; Pineda, Eduardo

    2010-01-01

    Tropical forests undergo continuous transformation to other land uses, resulting in landscapes typified by forest fragments surrounded by anthropogenic habitats. Small forest fragments, specifically strip-shaped remnants flanking streams (referred to as riparian remnants), can be particularly important for the maintenance and conservation of biodiversity within highly fragmented forests. We compared frog species diversity between riparian remnants, other forest fragments and cattle pastures in a tropical landscape in Los Tuxtlas, Mexico. We found similar species richness in the three habitats studied and a similar assemblage structure between riparian remnants and forest fragments, although species composition differed by 50 per cent. Frog abundance was halved in riparian remnants compared with forest fragments, but was twice that found in pastures. Our results suggest that riparian remnants play an important role in maintaining a portion of frog species diversity in a highly fragmented forest, particularly during environmentally stressful (hot and dry) periods. In this regard, however, the role of riparian remnants is complementary, rather than substitutive, with respect to the function of other forest fragments within the fragmented forest. PMID:20554561

  13. The Evolution and Fate of Super-Chandrasekhar Mass White Dwarf Merger Remnants

    NASA Astrophysics Data System (ADS)

    Schwab, Josiah; Quataert, Eliot; Kasen, Daniel

    2016-09-01

    We present stellar evolution calculations of the remnant of the merger of two carbon-oxygen white dwarfs (CO WDs). We focus on cases that have a total mass in excess of the Chandrasekhar mass. After the merger, the remnant manifests as an L ˜ 3 × 104 L⊙ source for ˜104 yr. A dusty wind may develop, leading these sources to be self-obscured and to appear similar to extreme AGB stars. Roughly ˜10 such objects should exist in the Milky Way and M31 at any time. As found in previous work, off-center carbon fusion is ignited within the merger remnant and propagates inward via a carbon flame, converting the WD to an oxygen-neon (ONe) composition. By following the evolution for longer than previous calculations, we demonstrate that after carbon-burning reaches the center, neutrino-cooled Kelvin-Helmholtz contraction leads to off-center neon ignition in remnants with masses ≥1.35 M⊙. The resulting neon-oxygen flame converts the core to a silicon WD. Thus, super-Chandrasekhar WD merger remnants do not undergo electron-capture induced collapse as traditionally assumed. Instead, if the remnant mass remains above the Chandrasekhar mass, we expect that it will form a low-mass iron core and collapse to form a neutron star. Remnants that lose sufficient mass will end up as massive, isolated ONe or Si WDs.

  14. Analysis of Shock Interactions and Supernova Morphology from Molecular Emission Around Young Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Charles; Bieging, J. H.; Rieke, G.

    2014-01-01

    We have observed the supernova remnant Cassiopeia A (Cas A) in the mid-infrared from 10-40 microns with the Spitzer Space Telescope and at millimeter wavelengths in 12CO and 13CO J=2-1 (230 and 220 GHz) with the Heinrich Hertz Submillimeter Telescope (HHSMT). Broadened (6 - 10 km/s) CO emission in the millimeter indicates that some molecular clouds towards the line of sight of the Cas A shock front have been shock broadened by ejecta from the remnant. The IR spectra demonstrate high-velocity emission along the northern shock front of the remnant coincident with bright radio continuum emission. These features trace a direct interaction with the Cas A shock front. Furthermore, some of the broadened molecular emission extends 1 - 2 arcminutes beyond the furthest extent of the SNR shock front. We infer from the proximity to the remnant as well as the positions of broadened CO emission that this material is accelerated by ejecta with velocity significantly larger than the observed free-expansion velocity of the Cas A shock front. This observation is consistent with a bipolar outflow as well as fast-moving ejecta pistons inferred in the Cas A remnant, in particular along the southwest to northeast axis of the remnant. We extend this type of analysis to other young, galactic supernova remnants in order to place constraints on the morphology and shock interactions during supernova events.

  15. Self-Adjustable Adhesion of Polyampholyte Hydrogels.

    PubMed

    Roy, Chanchal Kumar; Guo, Hong Lei; Sun, Tao Lin; Ihsan, Abu Bin; Kurokawa, Takayuki; Takahata, Masakazu; Nonoyama, Takayuki; Nakajima, Tasuku; Gong, Jian Ping

    2015-12-01

    Developing nonspecific, fast, and strong adhesives that can glue hydrogels and biotissues substantially promotes the application of hydrogels as biomaterials. Inspired by the ubiquitous adhesiveness of bacteria, it is reported that neutral polyampholyte hydrogels, through their self-adjustable surface, can show rapid, strong, and reversible adhesion to charged hydrogels and biological tissues through the Coulombic interaction.

  16. Nonwoven glass fiber mat reinforces polyurethane adhesive

    NASA Technical Reports Server (NTRS)

    Roseland, L. M.

    1967-01-01

    Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength.

  17. Interstellar and Ejecta Dust in the Cas A Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Arendt, Richard G.; Dwek, Eli; Kober, Gladys; Rho, Jonghee; Hwang, Una

    2013-01-01

    The ejecta of the Cas A supernova remnant has a complex morphology, consisting of dense fast-moving line emitting knots and diffuse X-ray emitting regions that have encountered the reverse shock, as well as more slowly expanding, unshocked regions of the ejecta. Using the Spitzer 5-35 micron IRS data cube, and Herschel 70, 100, and 160 micron PACS data, we decompose the infrared emission from the remnant into distinct spectral components associated with the different regions of the ejecta. Such decomposition allows the association of different dust species with ejecta layers that underwent distinct nuclear burning histories, and determination of the dust heating mechanisms. Our decomposition identified three characteristic dust spectra. The first, most luminous one, exhibits strong emission features at approx. 9 and 21 micron, and a weaker 12 micron feature, and is closely associated with the ejecta knots that have strong [Ar II] 6.99 micron and [Ar III] 8.99 micron emission lines. The dust features can be reproduced by magnesium silicate grains with relatively low MgO-to-SiO2 ratios. A second, very different dust spectrum that has no indication of any silicate features, is best fit by Al2O3 dust and is found in association with ejecta having strong [Ne II] 12.8 micron and [Ne III] 15.6 micron emission lines. A third characteristic dust spectrum shows features that best matched by magnesium silicates with relatively high MgO-to-SiO2 ratio. This dust is primarily associated with the X-ray emitting shocked ejecta and the shocked interstellar/circumstellar material. All three spectral components include an additional featureless cold dust component of unknown composition. Colder dust of indeterminate composition is associated with [Si II] 34.8 micron emission from the interior of the SNR, where the reverse shock has not yet swept up and heated the ejecta. The dust mass giving rise to the warm dust component is about approx. 0.1solar M. However, most of the dust mass

  18. SNR 1987A: the birth of a Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Bouchet, Patrice; Danziger, John

    Observations show that the infrared emission from dust observed in Supernovae and Supernova Remants originates both from the freshly synthesized dust in the expanding envelope and from pre-existing dust in the CSM. There are some few cases where it is suggested that dust formed recently in the CSM as a result of interaction with the expanding emvelope. The mass of dust in these various environments is, with a few exceptions, poorly determined. However the few estimates of the dust mass condensed in the ejecta make questionable so far any claims for supernovae being significant dust factories. This is the case in particular for SNR 1987A. We present up to date multiwavelength observations of this incipient remnant obtained with the VLT, Gemini, Chandra, Hubble and Spitzer Space Telescope. The various light curves show that the morphology and luminosity of the remnant are rapidly changing at X-ray, optical, and infrared wavelengths as the blast wave from the explosion expands into the circumstellar equatorial ring produced by mass loss from the progenitor 20000 years before the explosion. The observed IR/soft-X-ray flux ratio (IRX) is consistent with that of a dusty plasma with standard LMC dust abundances. This ratio decreased between days 6190 and 7137, providing the first direct observation of dust destruction, and has been remarkably stable since that date (up to day 8000), which might indicate that the episode of destruction has terminated. We show that the main components of the dust grains present in the ring are silicates and a model consistent with the observations has been elaborated. There remain some spectral features which are not explained. In addition, the lack of a strong correlation between images obtained in the visible (hot spots) and in the mid-infrared (dust clumps) also makes the precise location of the soft X-ray emitting region uncertain. The composition of the grains that have condensed in the ejecta of SN 1987A is still not known with

  19. Anatomic Graft Passage in Remnant-Preserving Posterior Cruciate Ligament Reconstruction

    PubMed Central

    Ahn, Jin Hwan; Lee, Sang Hak

    2014-01-01

    Posterior cruciate ligament (PCL) reconstruction with preservation of the remnant PCL fibers has been performed under the assumption that preserving the fibers contributes to knee kinematics, grafted tendon healing, and recovery of proprioception. This technical note presents a single-bundle, transtibial PCL reconstruction with anatomic graft passage between the remnant PCL fibers. The operation is performed using the posterior trans-septal portal, which can provide excellent visualization while preserving a large amount of remnant PCL fibers. In addition, this technique allows for anatomic graft passage without soft-tissue impingement, and it minimizes the risk of nonanatomic positioning of the PCL grafts. PMID:25473610

  20. DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY

    SciTech Connect

    Seward, F. D.; Charles, P. A.; Foster, D. L.; Dickel, J. R.; Romero, P. S.; Edwards, Z. I.; Perry, M.; Williams, R. M.

    2012-11-10

    A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M {sub Sun}.

  1. Endovascular Coiling of Aneurysm Remnants after Clipping in Patients with Follow-up

    PubMed Central

    Mangiafico, S.; Cellerini, M.; Villa, G.; Ammannati, F.; Paoli, L.; Mennonna, P.

    2005-01-01

    Summary The vast majority of intracranial aneurysms can be obliterated completely with surgical clipping. However, postoperative remnants occur in about 4 to 8% of patients who undergo postoperative angiography. Endovascular embolization has been successfully performed in patients with postoperative aneurysm remnant and it may represent a therapeutic alternative to surgical reintervention. Twelve aneurysm remnants after surgical clipping were treated with endovascular embolization using GDC. All aneurysms were located in the anterior circulation. Our experience confirms the feasibility and relative safety of this treatment strategy that may be considered a valid alternative to reintervention. PMID:20584434

  2. X-ray iron-line emission from the SN 185 remnant

    NASA Technical Reports Server (NTRS)

    Winkler, P. F.

    1979-01-01

    Radio and optical research was carried out in order to show that the supernova remnant RCW86 is a remnant of the earliest supernova event ever recorded in history (185 AD). The results are as follows: (1) an iron-line emission was found at 6.7 keV; (2) the temperature measured from HEAO-1 was approximately 6 keV; and (3) the equivalent width was consistent within the uncertainties with a cosmic iron abundance. These results support the identification of the supernova remnant RCW86 (it's X-ray source) with the historic supernova event.

  3. A Study of Supernova Remnants with Center-Filled X-Ray Morphology

    NASA Technical Reports Server (NTRS)

    Slane, Patrick O.

    2001-01-01

    The proposed study entails use of archival data, primarily from past and active X-ray observatories, to study the properties of a class of supernova remnants (SNRs) which display a centrally-bright X-ray morphology. Several models which have been proposed to explain the morphology are being investigated for comparisons with measured characteristics of several remnants: nonthermal emission from a central synchrotron nebula; thermal emission enhanced by slow evaporation of cool clouds in the hot SNR interior; and relic thermal emission from the SNR interior after the remnant has entered the radiative phase of evolution, thus causing the shell emission to cease.

  4. Esophagogastric reconstruction using remnant stomach with a single vessel pedicel: Technique and outcomes

    PubMed Central

    You, Bin; Hou, Sheng-cai; Li, Hui; Hu, Bin

    2014-01-01

    Esophageal cancer with a history of distal gastrectomy is a clinical problem. To our knowledge there have been no reports of remnant stomach fed from the left gastroepiploic artery being used in esophageal reconstruction. We, herein, report four cases of esophagogastric reconstruction using remnant stomach with a single left gastroepiploic vascular pedicel. It is more functional to use the remnant stomach than other replacements. Meanwhile, the gastric conduit fed from the left gastroepiploic artery showed sufficient vascularity and stable gastroesophageal anastomosis. The technique and outcomes in follow-up have proven feasible and save time. PMID:26767000

  5. The x-ray structure of the supernova remnant W49B

    NASA Technical Reports Server (NTRS)

    Dickel, John R.; Murphy, Rosa; Chu, You-Hua; Garcia, Guillermo; Goscha, Daniel

    1994-01-01

    Comparison of x-ray and radio images of W49B and other supernova remnants (SNR) provides detailed information on the mechanisms responsible for the emission and on the evolution of the remnants. There is faint x-ray emission from all parts of W49B but most of it is concentrated near the center of the remnant, unlike the radio emission which arises in a shell near the periphery. This structure indicates that this SNR is in the adolescent phase of its lifetime.

  6. [Journal selection and indexing for Index Medicus and Chinese periodicals indexed in Index Medicus].

    PubMed

    Zhou, Qing-Hui; Ling, Chang-Quan; Bai, Yu-Jin; Yin, Hui-Xia

    2005-01-01

    Index Medicus/MEDLINE/PubMed published by U. S. National Library of Medicine (NLM) is the most important and commonly used biomedical literature retrieval system in the world. According to the"List of Journals Indexed in Index Medicus (2004)", 4,098 journals are indexed for Index Medicus, including 70 journals from mainland China and Hong Kong and 9 journals from Taiwan. Journal of Chinese Integrative Medicine established in May, 2003 is indexed in Index Medicus in 2004. This article outlines the critical elements of journal selection for Index Medicus/MEDLINE and the journal selection process for indexing at NLM, and introduces some measures for the Journal of Chinese Integrative Medicine being indexed in Index Medicus/MEDLINE.

  7. Ceramic adhesive restorations and biomimetic dentistry: tissue preservation and adhesion.

    PubMed

    Tirlet, Gil; Crescenzo, Hélène; Crescenzo, Dider; Bazos, Panaghiotis

    2014-01-01

    Thanks to sophisticated adhesive techniques in contemporary dentistry, and the development of composite and ceramic materials, it is possible to reproduce a biomimetic match between substitution materials and natural teeth substrates. Biomimetics or bio-emulation allows for the association of two fundamental parameters at the heart of current therapeutic treatments: tissue preservation and adhesion. This contemporary concept makes the retention of the integrity of the maximum amount of dental tissue possible, while offering exceptional clinical longevity, and maximum esthetic results. It permits the conservation of the biological, esthetic, biomechanical and functional properties of enamel and dentin. Today, it is clearly possible to develop preparations allowing for the conservation of the enamel and dentin in order to bond partial restorations in the anterior and posterior sectors therefore limiting, as Professor Urs Belser from Geneva indicates, "the replacement of previous deficient crowns and devitalized teeth whose conservation are justified but whose residual structural state are insufficient for reliable bonding."1 This article not only addresses ceramic adhesive restoration in the anterior area, the ambassadors of biomimetic dentistry, but also highlights the possibility of occasionally integrating one or two restorations at the heart of the smile as a complement to extensive rehabilitations that require more invasive treatment.

  8. Ceramic adhesive restorations and biomimetic dentistry: tissue preservation and adhesion.

    PubMed

    Tirlet, Gil; Crescenzo, Hélène; Crescenzo, Dider; Bazos, Panaghiotis

    2014-01-01

    Thanks to sophisticated adhesive techniques in contemporary dentistry, and the development of composite and ceramic materials, it is possible to reproduce a biomimetic match between substitution materials and natural teeth substrates. Biomimetics or bio-emulation allows for the association of two fundamental parameters at the heart of current therapeutic treatments: tissue preservation and adhesion. This contemporary concept makes the retention of the integrity of the maximum amount of dental tissue possible, while offering exceptional clinical longevity, and maximum esthetic results. It permits the conservation of the biological, esthetic, biomechanical and functional properties of enamel and dentin. Today, it is clearly possible to develop preparations allowing for the conservation of the enamel and dentin in order to bond partial restorations in the anterior and posterior sectors therefore limiting, as Professor Urs Belser from Geneva indicates, "the replacement of previous deficient crowns and devitalized teeth whose conservation are justified but whose residual structural state are insufficient for reliable bonding."1 This article not only addresses ceramic adhesive restoration in the anterior area, the ambassadors of biomimetic dentistry, but also highlights the possibility of occasionally integrating one or two restorations at the heart of the smile as a complement to extensive rehabilitations that require more invasive treatment. PMID:25126616

  9. Neutrino-driven winds from neutron star merger remnants

    NASA Astrophysics Data System (ADS)

    Perego, A.; Rosswog, S.; Cabezón, R. M.; Korobkin, O.; Käppeli, R.; Arcones, A.; Liebendörfer, M.

    2014-10-01

    We present a detailed, three-dimensional hydrodynamic study of the neutrino-driven winds emerging from the remnant of a neutron star merger. Our simulations are performed with the Newtonian, Eulerian code FISH, augmented by a detailed, spectral neutrino leakage scheme that accounts for neutrino absorption. Consistent with earlier two-dimensional studies, a strong baryonic wind is blown out along the original binary rotation axis within ≈100 ms. From this model, we compute a lower limit on the expelled mass of 3.5 × 10-3 M⊙, relevant for heavy element nucleosynthesis. Because of stronger neutrino irradiation, the polar regions show substantially larger electron fractions than those at lower latitudes. The polar ejecta produce interesting r-process contributions from A ≈ 80 to about 130, while the more neutron-rich, lower latitude parts produce elements up to the third r-process peak near A ≈ 195. We calculate the properties of electromagnetic transients powered by the radioactivity in the wind, in addition to the `macronova' transient stemming from the dynamic ejecta. The polar regions produce ultraviolet/optical transients reaching luminosities up to 1041 erg s-1, which peak around 1 d in optical and 0.3 d in bolometric luminosity. The lower latitude regions, due to their contamination with high-opacity heavy elements, produce dimmer and more red signals, peaking after ˜2 d in optical and infrared.

  10. The Fate of the Compact Remnant in Neutron Star Mergers

    DOE PAGES

    Fryer, Chris L.; Belczynski, Krzysztoff; Ramirez-Ruiz, Enrico; Rosswog, Stephan; Shen, Gang; Steiner, Andrew W.

    2015-10-06

    Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the coresmore » of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.« less

  11. THE FATE OF THE COMPACT REMNANT IN NEUTRON STAR MERGERS

    SciTech Connect

    Fryer, Chris L.; Belczynski, Krzysztoff; Ramirez-Ruiz, Enrico; Rosswog, Stephan; Shen, Gang; Steiner, Andrew W.

    2015-10-10

    Neutron star (binary neutron star and neutron star–black hole) mergers are believed to produce short-duration gamma-ray bursts (GRBs). They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and advanced VIRGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of Newtonian merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3–2.4 solar masses. If quick black hole formation is essential in producing GRBs, LIGO/Virgo observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.

  12. A NEW EVOLUTIONARY PHASE OF SUPERNOVA REMNANT 1987A

    SciTech Connect

    Park, Sangwook; Zhekov, Svetozar A.; Burrows, David N.; Racusin, Judith L.; McCray, Richard

    2011-06-01

    We have been monitoring the supernova remnant (SNR) 1987A with Chandra observations since 1999. Here we report on the latest change in the soft X-ray light curve of SNR 1987A. For the last {approx}1.5 yr (since day {approx}8000), the soft X-ray flux has significantly flattened, staying (within uncertainties) at f{sub X} {approx} 5.7 x 10{sup -12} erg cm{sup -2} s{sup -1} (corresponding to L{sub X} {approx} 3.6 x 10{sup 36} erg s{sup -1}) in the 0.5-2 keV band. This remarkable change in the recent soft X-ray light curve suggests that the forward shock is now interacting with a decreasing density structure, after interacting with an increasing density gradient over {approx}10 yr prior to day {approx}8000. Possibilities may include the case that the shock is now propagating beyond a density peak of the inner ring. We briefly discuss some possible implications on the nature of the progenitor and the future prospects of our Chandra monitoring observations.

  13. WHAM Observations of High-latitude Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Orchard, Alexander; Haffner, L. Matthew; Benjamin, Robert A.; Gostisha, Martin

    2016-01-01

    The Wisconsin H-Alpha Mapper Sky Survey (WHAM-SS) traces numerous large-angle, diffuse regions containing filamentary and shell-like structures. The largest of these are complex supershells that harbor recent and on-going star formation, such as the Orion-Eridanus complex, the Gum Nebula, and the extended emission above and below the W3/W4/W5 star-forming regions in the Perseus Arm. Several large-diameter regions with simpler morphologies are also present, which we focus on here. While some of these structures are diffuse H II regions powered by nearby, isolated stars, others are clearly supernova remnants (SNRs) due to their association with X-ray or non-thermal radio emission. We highlight the structure, kinematics, and multi-wavelength properties of several SNRs using Hα maps from the WHAM-SS and data from on-going WHAM multi-wavelength surveys. WHAM research and operations are supported through NSF Award AST-1108911.

  14. Evolution of Pulsar Wind Nebulae inside Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Temim, T.

    2016-06-01

    Composite supernova remnants (SNRs) are those consisting of both a central pulsar that produces a wind of synchrotron-emitting relativistic particle and a supernova (SN) blast wave that expands into the surrounding interstellar medium (ISM). The evolution of the pulsar wind nebula (PWN) is coupled to the evolution of its host SNR and characterized by distinct stages, from the PWN's early expansion into the unshocked SN ejecta to its late-phase interaction with the SNR reverse shock. I will present an overview of the various evolutionary stages of composite SNRs and show how the signatures of the PWN/SNR interaction can reveal important information about the SNR and PWN dynamics, the SN progenitor and explosion asymmetry, the properties of the SN ejecta and newly-formed dust, particle injection and loss processes, and the eventual escape of energetic particles into the ISM. I will also discuss recent multi-wavelength observations and hydrodynamical modeling of evolved systems in which the PWN interacts with the SNR reverse shock and discuss their implications for our general understanding of the structure and evolution of composite SNRs.

  15. Understanding the Balmer Bubble in the Vela Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Chinn, Brian; Smith, C.; Points, S.; Heathcote, S.

    2014-01-01

    We present imaging and spectroscopic data and analysis of the Balmer-dominated filament that is ahead of the eastern edge of the radiative shock of Bullet C in the Vela Supernova Remnant. This filament was discovered in 2002 by Carlin & Smith(2002), and was suggested to be a non-radiative shock. Images of the filament were taken using Hα and R band filters on the SMARTS 0.9m telescope at CTIO. These images were then compared to images taken in 2006 using the MOSAIC II imager on the Blanco Telescope at CTIO, in an attempt to detect proper motion of the filament. Comparison over the 7 year baseline failed to show proper motion of the filament. From this result, we are able to place an upper limit of ~270 km/s on the velocity of the Balmer-dominated filament. We also obtained moderate resolution spectra of the Balmer-dominated filament and the radiative shock using the Goodman Spectrograph at SOAR Telescope. Spectroscopic analysis of the Balmer-dominated filament failed to detect a broad component of the Hα emission line, which would be expected for a high velocity non-radiative shock.

  16. Grammage of cosmic rays around Galactic supernova remnants

    NASA Astrophysics Data System (ADS)

    D'Angelo, Marta; Blasi, Pasquale; Amato, Elena

    2016-10-01

    The residence time of cosmic rays (CRs) in the Galaxy is usually inferred from the measurement of the ratio of secondary-to-primary nuclei, for instance the boron (B)/carbon (C) ratio, which provides an estimate of the amount of matter traversed by CRs during their propagation, the so-called CR grammage. However, after being released by their parent sources, for instance, supernova remnants, CRs must cross the disc of the Galaxy, before entering the much lower density halo, in which they are believed to spend most of their time before eventually escaping the Galaxy. In the near-source region, the CR propagation is shown to be dominated by the nonlinear self-generation of waves. Here we show that due to this effect, the time that CRs with energies up to ˜10 TeV spend within a distance Lc˜100 pc from the sources is much larger than naive estimates would suggest. Depending on the level of ionization of the medium surrounding the source, the grammage accumulated in the source vicinity may be a non-negligible fraction of the total grammage traversed throughout the whole Galaxy. Moreover, there is an irreducible grammage that CRs traverse while trapped downstream of the shock that accelerated them, though this contribution is rather uncertain. We conclude that some caution should be used in inferring parameters of Galactic CR propagation from measurements of the B/C ratio.

  17. A XMM Survey for Compact Objects in Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.

    2004-01-01

    The goal of the project is to identify candidate neutron stars in Galactic supernova remnants (SNRs) through their X-ray emission. With XMM we observed the SNRs and typically find 10 - 50 X-ray sources. Almost all are either background galaxies or foreground stars. Therefore we must also pursue detailed optical/infrared follow-up observations to find counterparts for these X-ray sources and classify them. At the depth of the XMM observations, practically all confusing X-ray sources should have identifiable optical/IR counterparts. We have done a preliminary analysis of the XMM data and identified likely counterparts to the X-ray sources from available surveys(DSS, 2MASS). We then obtained wide-field optical/IR data from Palomar to get counterparts for the remaining sources. This analysis is underway: while often a single bright source is in the XMM error circle and can be considered a counterpart, in a number of cases we must do more detailed studies and evaluate several fainter optical/lR sources. We hope to have the final analysis of the XMM + Palomar data done this Fall. It is possible that additional, deeper optical/IR data may be necessary. We expect to publish our results by the end of this year.

  18. SUPERNOVA REMNANTS AND STAR FORMATION IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Desai, Karna M.; Chu, You-Hua; Gruendl, Robert A.; Dluger, William; Katz, Marshall; Wong, Tony; Looney, Leslie W.; Chen, C.-H. Rosie; Hughes, Annie; Muller, Erik; Ott, Juergen; Pineda, Jorge L.

    2010-08-15

    It has often been suggested that supernova remnants (SNRs) can trigger star formation. To investigate the relationship between SNRs and star formation, we have examined the known sample of 45 SNRs in the Large Magellanic Cloud (LMC) to search for associated young stellar objects (YSOs) and molecular clouds. We find seven SNRs associated with both YSOs and molecular clouds, three SNRs associated with YSOs but not molecular clouds, and eight SNRs near molecular clouds but not associated with YSOs. Among the 10 SNRs associated with YSOs, the association between the YSOs and SNRs either can be rejected or cannot be convincingly established for eight cases. Only two SNRs have YSOs closely aligned along their rims; however, the time elapsed since the SNR began to interact with the YSOs' natal clouds is much shorter than the contraction timescales of the YSOs, and thus we do not see any evidence of SNR-triggered star formation in the LMC. The 15 SNRs that are near molecular clouds may trigger star formation in the future when the SNR shocks have slowed down to <45 km s{sup -1}. We discuss how SNRs can alter the physical properties and abundances of YSOs.

  19. Asymmetric velocity anisotropies in remnants of collisionless mergers

    SciTech Connect

    Sparre, Martin; Hansen, Steen H. E-mail: hansen@dark-cosmology.dk

    2012-07-01

    Dark matter haloes in cosmological N-body simulations are affected by processes such as mergers, accretion and the gravitational interaction with baryonic matter. Typically the analysis of dark matter haloes is performed in spherical or elliptical bins and the velocity distributions are often assumed to be constant within those bins. However, the velocity anisotropy, which describes differences between the radial and tangential velocity dispersion, has recently been show to have a strong dependence on direction in the triaxial halos formed in cosmological simulations. In this study we derive properties of particles in cones parallel or perpendicular to the collision axis of merger remnants. We find that the velocity anisotropy has a strong dependence on direction. The finding that the direction-dependence of the velocity anisotropy of a halo depends on the merger history, explains the existence of such trends in cosmological simulations. It also explains why a large diversity is seen in the velocity anisotropy profiles in the outer parts of high-resolution simulations of cosmological haloes.

  20. Non-cosmological FRBs from young supernova remnant pulsars

    NASA Astrophysics Data System (ADS)

    Connor, Liam; Sievers, Jonathan; Pen, Ue-Li

    2016-05-01

    We propose a new extra but non-cosmological explanation for fast radio bursts (FRBs) based on very young pulsars in supernova remnants. Within a few hundred years of a core-collapse supernova, the ejecta is confined within ˜1 pc, providing a high enough column density of free electrons for the observed 375-1600 pc cm-3 of dispersion measure (DM). By extrapolating a Crab-like pulsar to its infancy in an environment like that of SN 1987A, we hypothesize such an object could emit supergiant pulses sporadically which would be bright enough to be seen at a few hundred megaparsecs. We hypothesize that such supergiant pulses would preferentially occur early in the pulsar's life when the free electron density is still high, which is why we do not see large numbers of moderate DM FRBs (≲300 pc cm-3). In this scenario, Faraday rotation at the source gives rotation measures (RMs) much larger than the expected cosmological contribution. If the emission were pulsar-like, then the polarization vector could swing over the duration of the burst, which is not expected from non-rotating objects. In this model, the scattering, large DM, and commensurate RM all come from one place which is not the case for the cosmological interpretation. The model also provides testable predictions of the flux distribution and repeat rate of FRBs, and could be furthermore verified by spatial coincidence with optical supernovae of the past several decades and cross-correlation with nearby galaxy maps.

  1. Fermi-LAT Observation of Supernova Remnant S147

    SciTech Connect

    Katsuta, J.; Uchiyama, Y.; Tanaka, T.; Tajima, H.; Bechtol, K.; Funk, S.; Lande, J.; Ballet, J.; Hanabata, Y.; Lemoine-Goumard, M.; Takahashi, T.; /JAXA, Sagamihara

    2012-08-17

    We present an analysis of gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region around SNR S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) x 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 x 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with prominent H{alpha} filaments of S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. Reacceleration of pre-existing CRs and subsequent adiabatic compression in the filaments is sufficient to provide the required energy density of high-energy protons.

  2. Expectation on Observation of Supernova Remnants with the LHAASO Project

    NASA Astrophysics Data System (ADS)

    Liu, Ye; Cao, Zhen; Chen, Songzhan; Chen, Yang; Cui, Shuwang; He, Huihai; Huang, Xingtao; Ma, Xinhua; Yuan, Qiang; Zhang, Xiao; LHAASO Collaboration

    2016-07-01

    Supernova remnants (SNRs) are believed to be the most important acceleration sites for cosmic rays (CRs) below ˜1015 eV in the Galaxy. High-energy photons, either directly from the shocks of the SNRs or indirectly from the interaction between SNRs and the nearby clouds, are crucial probes for the CR acceleration. Big progresses on observations of SNRs have been achieved by space- and ground-based γ-ray facilities. However, whether γ-rays come from accelerated hadrons or not, as well as their connection with the CRs observed at Earth, remains in debate. Large High Altitude Air Shower Observatory (LHAASO), a next-generation experiment, is designed to survey the northern part of the very high energy γ-ray sky from ˜0.3 TeV to PeV with the sensitivity of ≲1% of the Crab Nebula flux. In this paper, we indicate that LHAASO will be dedicated to enlarging the γ-ray SNR samples and improving the spectral and morphological measurements. These measurements, especially at energies above 30 TeV, will be important for us to finally understand the CR acceleration in SNRs.

  3. Primary versus Secondary Leptons in the EGRET Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Fatuzzo, Marco; Melia, Fulvio

    2005-09-01

    The EGRET supernova remnants (SNRs) are all expanding into nearby dense molecular clouds, powering a shock at the interface where protons and electrons accelerate to relativistic energies. A viable mechanism for the emission of γ-rays in these sources is the decay of neutral pions created in collisions between the relativistic hadrons and protons in the ambient medium. But neutral pion decay alone cannot reproduce the whole high-energy spectrum, particularly below 100 MeV. A pion decay scenario thus requires a lepton population to fill in the lower part of the spectrum via bremsstrahlung emission. This population, however, is constrained by the SNR radio spectrum. Taking our cue from the behavior of Sgr A East, an energetic EGRET SNR at the Galactic center, we here examine the role played in these sources by secondary leptons-electrons and positrons produced in proton-proton scattering events and the ensuing particle cascades. We show that, while secondary leptons cannot account for the γ-rays below 100 MeV, they can account for the hard radio spectra observed from the EGRET SNRs. Thus, it appears that both primary and secondary leptons may be important contributors to the overall broadband emission from these sources, but if so, they must radiate most of their energy in different parts of the SNR-cloud environment. We show that shock acceleration in dense cores being overtaken by the expanding SNR shell can naturally lead to such a scenario.

  4. HST/ACS Narrowband Imaging of the Kepler Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Sankrit, Ravi; Blair, William P.; Frattare, Lisa M.; Rudnick, Lawrence; DeLaney, Tracey; Harrus, Ilana M.; Ennis, Jessica A.

    2007-01-01

    We present narrowband images of the Kepler supernova remnant obtained with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The images, with an angular resolution of 0.05" reveal the structure of the emitting gas in unprecedented detail. Radiative and nonradiative shocks are found in close proximity, unresolvable in gromd-based spectra, indicating that the pre-shock medium is highly clumped. The ionization structure, traced by differences in the [0 111] to [N 11] flux ratio, varies on subarcsecond scales. The variation is due to 110th differences in shock velocity as well as gradients in the evolutionary stage of the shocks. A prollinent complex of knots protruding beyond the boundary of the rennallt in the northwest is found to consist of bright radiative knots, collected by arcuate nonradiative filaments. Based on the coincidence of the optical emission with a bright isolated knot of X-ray emission, we infer that this feature is due to a Rayleigh-Taylor finger that formed at the contact discontinuity and overtook the primary blast wave.

  5. The Fate of the Compact Remnant in Neutron Star Mergers

    SciTech Connect

    Fryer, Chris L.; Belczynski, Krzysztoff; Ramirez-Ruiz, Enrico; Rosswog, Stephan; Shen, Gang; Steiner, Andrew W.

    2015-10-06

    Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.

  6. Search for surviving companions in type Ia supernova remnants

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E. E-mail: pmricker@illinois.edu E-mail: taam@asiaa.sinica.edu.tw

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  7. SLOW DIFFUSION OF COSMIC RAYS AROUND A SUPERNOVA REMNANT

    SciTech Connect

    Fujita, Yutaka; Ohira, Yutaka; Takahara, Fumio

    2010-04-01

    We study the escape of cosmic-ray protons accelerated at a supernova remnant (SNR). We are interested in their propagation in the interstellar medium (ISM) after they leave the shock neighborhood where they are accelerated, but when they are still near the SNR with their energy density higher than that in the average ISM. Using Monte Carlo simulations, we found that the cosmic rays with energies of {approx}< TeV excite Alfven waves around the SNR on a scale of the SNR itself if the ISM is highly ionized. Thus, even if the cosmic rays can leave the shock, scattering by the waves prevents them from moving further away from the SNR. The cosmic rays form a slowly expanding cosmic-ray bubble, and they spend a long time around the SNR. This means that the cosmic rays cannot actually escape from the SNR until a fairly late stage of the SNR evolution. This is consistent with some results of Fermi and H.E.S.S. observations.

  8. Numerical Simulations of Dust Destruction in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Silvia, Devin W.; Smith, B. D.; Shull, J. M.

    2010-01-01

    We investigate the destruction of newly-formed dust grains by sputtering in the reverse shocks of supernova remnants through hydrodynamic simulations.  Using an idealized setup of planar shock impacting a dense, spherical clump, we implant a population of Lagrangian particles into the clump to represent a distribution of dust grains, then post-process the simulation output to calculate the grain sputtering for a variety of species and size distributions. We explore the parameter space appropriate for this problem by altering the over-density of the ejecta clump, the density profile of the clump, and the speed of the reverse shock. Since radiative cooling could lower the temperature of the medium in which the dust is embedded and potentially protect the dust by slowing or halting grain sputtering, we study the effects of different cooling methods over the time scale of the simulations.  We also consider the influence of increased projectile mass on sputtering yields in metal-enriched plasmas. In general, results indicate that grains with radii less than 0.1 microns are sputtered to much smaller radii and often destroyed completely, while larger grains tend to survive their interaction with the reverse shock. The survival rate of grains formed by supernovae in the early universe is crucial in determining whether or not they can act as the "dust factories” needed to explain high-redshift dust mass estimates.

  9. Acceleration of cosmic rays in supernova-remnants

    NASA Technical Reports Server (NTRS)

    Dorfi, E. A.; Drury, L. O.

    1985-01-01

    It is commonly accepted that supernova-explosions are the dominant source of cosmic rays up to an energy of 10 to the 14th power eV/nucleon. Moreover, these high energy particles provide a major contribution to the energy density of the interstellar medium (ISM) and should therefore be included in calculations of interstellar dynamic phenomena. For the following the first order Fermi mechanism in shock waves are considered to be the main acceleration mechanism. The influence of this process is twofold; first, if the process is efficient (and in fact this is the cas) it will modify the dynamics and evolution of a supernova-remnant (SNR), and secondly, the existence of a significant high energy component changes the overall picture of the ISM. The complexity of the underlying physics prevented detailed investigations of the full non-linear selfconsistent problem. For example, in the context of the energy balance of the ISM it has not been investigated how much energy of a SN-explosion can be transfered to cosmic rays in a time-dependent selfconsistent model. Nevertheless, a lot of progress was made on many aspects of the acceleration mechanism.

  10. Approximation of muscle remnants improves cosmesis following hemimandibulectomy.

    PubMed

    Chaturvedi, P

    2009-10-01

    Hemimandibulectomy should be avoided whenever possible, as it results in significant deterioration in quality of life. If hemimandibulectomy is unavoidable, attempts should be made to reconstruct the bone and soft tissue defect by free tissue transfer or a pedicled flap such as a pectoralis major myocutaneous flap. Bony reconstruction may become challenging when oncological safety mandates removal of the vertical ramus or the condyle. Elderly patients and those with significant co-morbidity are not suitable for prolonged microvascular surgery. Oral cancer is a disease of impoverished nations, where most health institutions may not have the infrastructure to offer microvascular reconstruction. The pectoralis major myocutaneous flap, the workhorse for reconstruction of such defects, occasionally has limitations in terms of bulk, limited arc of rotation, shoulder dysfunction etc. Therefore, hemimandibulectomy and primary mucosal closure continues to be a common procedure in developing nations. A simple technique is proposed with which to improve cosmesis following hemimandibulectomy, utilising the locally available muscle remnants. In highly selected patients, the remaining muscles can be approximated to prevent the lateral hollow that is a common but unacceptable sequel to hemimandibulectomy. PMID:19566975

  11. Genetic rescue of remnant tropical trees by an alien pollinator.

    PubMed Central

    Dick, C. W.

    2001-01-01

    Habitat fragmentation is thought to lower the viability of tropical trees by disrupting their mutualisms with native pollinators. However, in this study, Dinizia excelsa (Fabaceae), a canopy-emergent tree, was found to thrive in Amazonian pastures and forest fragments even in the absence of native pollinators. Canopy observations indicated that African honeybees (Apis mellifera scutellata) were the predominant floral visitors in fragmented habitats and replaced native insects in isolated pasture trees. Trees in habitat fragments produced, on average, over three times as many seeds as trees in continuous forest, and microsatellite assays of seed arrays showed that genetic diversity was maintained across habitats. A paternity analysis further revealed gene flow over as much as 3.2 km of pasture, the most distant pollination precisely recorded for any plant species. Usually considered only as dangerous exotics, African honeybees have become important pollinators in degraded tropical forests, and may alter the genetic structure of remnant populations through frequent long-distance gene flow. PMID:11703880

  12. High Energy Signatures of POST Adiabatic Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Telezhinsky, Igor; Hnatyk, Bohdan

    Between the well-known adiabatic and radiative stages of the Supernova remnant (SNR) evolution there is, in fact, a transition stage with a duration comparable to the duration of adiabatic one. Physical existence of the transition stage is motivated by cooling of some part of the downstream hot gas with formation of a thin cold shell that is joined to a shell of swept up interstellar medium (ISM). We give an approximate analytical method for full hydrodynamical description of the transition stage. On its base we investigate the evolution of X-ray and γ-ray radiation during this stage. It is shown that formation of a dense shell during the transition stage is accompanied by the decrease of X-ray luminosity because of hot gas cooling and increase of gamma-ray flux according to the increase of target proton density and CR energy in the newly born shell. The role of nonuniformity of ISM and its influence on the high energy fluxes from the SNRs is also discussed.

  13. Search for Surviving Companions in Type Ia Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E.

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  14. Chandra observation of the supernova remnant N11L

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Chen, Yang; Chu, You-Hua; Williams, Rosa M.

    2016-06-01

    We performed a Chandra X-ray study of the supernova remnant (SNR) N11L in the Large Magellanic Cloud (LMC). The X-ray emission is predominantly distributed within the main shell and the northern loop-like filaments traced by the optical narrow band images, with an indistinct extension along the north area. The brightest emission comes from a northeast-southwest ridge, and peaks at two patches at center and southwest. Spectral analysis indicates that the blast wave is propagating in a inhomogenous environment, and the X-ray emission overall is dominated by thermal gas whose composition is consistent with the LMC average abundance. The ionization time of the hot plasma implied by the X-ray spectral analysis is consistent with the Sedov age of the SNR derived from the best-fit parameters and the apparent radius of the SNR based on the optical images, however, the consequent explosion energy is no only at least one order of magnitude less than the canonical value of 10^{51} ergs, but also takes a small portion of the thermal energy of the hot gas. That discrepancy supports the blown-out scenario.

  15. A Newly Recognized Very Young Supernova Remnant in M83

    NASA Astrophysics Data System (ADS)

    Blair, William P.; Winkler, P. Frank; Long, Knox S.; Whitmore, Bradley C.; Kim, Hwihyun; Soria, Roberto; Kuntz, K. D.; Plucinsky, Paul P.; Dopita, Michael A.; Stockdale, Christopher

    2015-01-01

    As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and GMOS, we have discovered one object whose spectrum shows very broad lines at Halpha, [O I] 6300, and [O III] 5007, similar to those from other objects classified as `late time supernovae.' Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was not observed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 M(sun), and the presence of broad Halpha in the spectrum makes a type II supernova likely. The supernova must predate the 1983 VLA radio detection of the object. We suggest examination of archival images of M83 to search for evidence of the supernova event that gave rise to this object, and thus provide a precise time since the explosion.We acknowledge STScI grants under the umbrella program ID GO-12513 to Johns Hopkins University, STScI, and Middlebury College. PFW acknowledges additional support from the National Science Foundation through grant AST-0908566.

  16. IS THERE A HIDDEN HOLE IN TYPE Ia SUPERNOVA REMNANTS?

    SciTech Connect

    Garcia-Senz, D.; Badenes, C.; Serichol, N. E-mail: carles@astro.tau.ac.il

    2012-01-20

    In this paper, we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova (SN Ia) explosion. In particular we are interested in the long-term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant (SNR) after several centuries of evolution, which is a hot topic in current SN Ia studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the SNR resulting from the interaction of this ejected material with the ambient medium. Our aim is to use SNR observations to constrain the single degenerate scenario for SN Ia progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that approach the edge of the forward shock. We also discuss other geometrical properties of the simulations, like the evolution of the contact discontinuity.

  17. Pervasive Defaunation of Forest Remnants in a Tropical Biodiversity Hotspot

    PubMed Central

    Canale, Gustavo R.; Peres, Carlos A.; Guidorizzi, Carlos E.; Gatto, Cassiano A. Ferreira; Kierulff, Maria Cecília M.

    2012-01-01

    Tropical deforestation and forest fragmentation are among the most important biodiversity conservation issues worldwide, yet local extinctions of millions of animal and plant populations stranded in unprotected forest remnants remain poorly explained. Here, we report unprecedented rates of local extinctions of medium to large-bodied mammals in one of the world's most important tropical biodiversity hotspots. We scrutinized 8,846 person-years of local knowledge to derive patch occupancy data for 18 mammal species within 196 forest patches across a 252,669-km2 study region of the Brazilian Atlantic Forest. We uncovered a staggering rate of local extinctions in the mammal fauna, with only 767 from a possible 3,528 populations still persisting. On average, forest patches retained 3.9 out of 18 potential species occupancies, and geographic ranges had contracted to 0–14.4% of their former distributions, including five large-bodied species that had been extirpated at a regional scale. Forest fragments were highly accessible to hunters and exposed to edge effects and fires, thereby severely diminishing the predictive power of species-area relationships, with the power model explaining only ∼9% of the variation in species richness per patch. Hence, conventional species-area curves provided over-optimistic estimates of species persistence in that most forest fragments had lost species at a much faster rate than predicted by habitat loss alone. PMID:22905103

  18. OH Zeeman Magnetic Field Detections Toward Five Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Brogan, C. L.; Frail, D. A.; Goss, W. M.; Troland, T. H.

    1999-12-01

    We have observed OH (1720 MHz) masers in five galactic SNRs with the VLA to measure their magnetic field strengths using the Zeeman effect. We detected all 12 of the bright (Sν > 200 mJy) OH (1720 MHz) masers previously detected by Frail et al. (1996) and Green et al. (1997) and measured significant magnetic fields (i.e. > 3σ ) in ten of them. Assuming that the ``thermal'' Zeeman equation can be used to estimate | B| for OH masers, our estimated fields range from 0.2 to 2 mG. We show that these magnetic field strengths are consistent with the hypothesis that ambient molecular cloud magnetic fields are compressed via the SNR shock to the observed values. Magnetic fields of this magnitude exert a considerable influence on the properties of the cloud with the magnetic pressures (10-7 - 10-9 erg cm-3) exceeding the pressure in the ISM or even the thermal pressure of the hot gas interior to the remnant. This study brings the number of galactic SNRs with OH (1720 MHz) Zeeman detections to ten. This work was supported by the NRAO.

  19. Indexing Consistency and Quality.

    ERIC Educational Resources Information Center

    Zunde, Pranas; Dexter, Margaret E.

    Proposed is a measure of indexing consistency based on the concept of "fuzzy sets." By this procedure a higher consistency value is assigned if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on…

  20. Comparative Index Terms.

    ERIC Educational Resources Information Center

    Rasheed, Muhammad Abdur

    1989-01-01

    Describes a study that compared indexing terms suggested by authors of articles in "The American Journal of the Medical Science" and indexing terms assigned to the same articles in MEDLARS. Case studies are used to examine the differences between author and indexer indexing. (CLB)

  1. Quaker Resources Online Index.

    ERIC Educational Resources Information Center

    Beke-Harrigan, Heidi

    The Quaker Resources Online Index is a World Wide Web-based index, including author, title, subject, and meeting indexes, that provides access to Quaker materials available on the Web. Given the current failings and shortcomings of search engines and automated key word searches, this index brings together information from a variety of sources and…

  2. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A.; Guo, Zhen

    1999-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  3. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A.; Guo, Zhen

    2001-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  4. Gecko adhesion pad: a smart surface?

    NASA Astrophysics Data System (ADS)

    Pesika, Noshir S.; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  5. Gecko adhesion pad: a smart surface?

    PubMed

    Pesika, Noshir S; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-18

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  6. Nanocapillary Adhesion between Parallel Plates.

    PubMed

    Cheng, Shengfeng; Robbins, Mark O

    2016-08-01

    Molecular dynamics simulations are used to study capillary adhesion from a nanometer scale liquid bridge between two parallel flat solid surfaces. The capillary force, Fcap, and the meniscus shape of the bridge are computed as the separation between the solid surfaces, h, is varied. Macroscopic theory predicts the meniscus shape and the contribution of liquid/vapor interfacial tension to Fcap quite accurately for separations as small as two or three molecular diameters (1-2 nm). However, the total capillary force differs in sign and magnitude from macroscopic theory for h ≲ 5 nm (8-10 diameters) because of molecular layering that is not included in macroscopic theory. For these small separations, the pressure tensor in the fluid becomes anisotropic. The components in the plane of the surface vary smoothly and are consistent with theory based on the macroscopic surface tension. Capillary adhesion is affected by only the perpendicular component, which has strong oscillations as the molecular layering changes.

  7. Particle adhesion in powder coating

    SciTech Connect

    Mazumder, M.K.; Wankum, D.L.; Knutson, M.; Williams, S.; Banerjee, S.

    1996-12-31

    Electrostatic powder coating is a widely used industrial painting process. It has three major advantages: (1) it provides high quality durable finish, (2) the process is environmentally friendly and does not require the use of organic solvents, and (3) it is economically competitive. The adhesion of electrostatically deposited polymer paint particles on the grounded conducting substrate depends upon many parameters: (a) particle size and shape distributions, (b) electrostatic charge distributions, (c) electrical resistivity, (d) dielectric strength of the particles, (e) thickness of the powder film, (f) presence and severity of the back corona, and (g) the conductivity and surface properties of the substrate. The authors present a model on the forces of deposition and adhesion of corona charged particles on conducting substrates.

  8. Nanocapillary Adhesion between Parallel Plates.

    PubMed

    Cheng, Shengfeng; Robbins, Mark O

    2016-08-01

    Molecular dynamics simulations are used to study capillary adhesion from a nanometer scale liquid bridge between two parallel flat solid surfaces. The capillary force, Fcap, and the meniscus shape of the bridge are computed as the separation between the solid surfaces, h, is varied. Macroscopic theory predicts the meniscus shape and the contribution of liquid/vapor interfacial tension to Fcap quite accurately for separations as small as two or three molecular diameters (1-2 nm). However, the total capillary force differs in sign and magnitude from macroscopic theory for h ≲ 5 nm (8-10 diameters) because of molecular layering that is not included in macroscopic theory. For these small separations, the pressure tensor in the fluid becomes anisotropic. The components in the plane of the surface vary smoothly and are consistent with theory based on the macroscopic surface tension. Capillary adhesion is affected by only the perpendicular component, which has strong oscillations as the molecular layering changes. PMID:27413872

  9. The Index cohesive effect on stock market correlations

    NASA Astrophysics Data System (ADS)

    Shapira, Y.; Kenett, D. Y.; Ben-Jacob, E.

    2009-12-01

    We present empirical examination and reassessment of the functional role of the market Index, using datasets of stock returns for eight years, by analyzing and comparing the results for two very different markets: 1) the New York Stock Exchange (NYSE), representing a large, mature market, and 2) the Tel Aviv Stock Exchange (TASE), representing a small, young market. Our method includes special collective (holographic) analysis of stock-Index correlations, of nested stock correlations (including the Index as an additional ghost stock) and of bare stock correlations (after subtraction of the Index return from the stocks returns). Our findings verify and strongly substantiate the assumed functional role of the index in the financial system as a cohesive force between stocks, i.e., the correlations between stocks are largely due to the strong correlation between each stock and the Index (the adhesive effect), rather than inter-stock dependencies. The Index adhesive and cohesive effects on the market correlations in the two markets are presented and compared in a reduced 3-D principal component space of the correlation matrices (holographic presentation). The results provide new insights into the interplay between an index and its constituent stocks in TASE-like versus NYSE-like markets.

  10. Host Selection of Microbiota via Differential Adhesion.

    PubMed

    McLoughlin, Kirstie; Schluter, Jonas; Rakoff-Nahoum, Seth; Smith, Adrian L; Foster, Kevin R

    2016-04-13

    The host epithelium is the critical interface with microbial communities, but the mechanisms by which the host regulates these communities are poorly understood. Here we develop the hypothesis that hosts use differential adhesion to select for and against particular members of their microbiota. We use an established computational, individual-based model to study the impact of host factors that regulate adhesion at the epithelial surface. Our simulations predict that host-mediated adhesion can increase the competitive advantage of microbes and create ecological refugia for slow-growing species. We show how positive selection via adhesion can be transformed into negative selection if the host secretes large quantities of a matrix such as mucus. Our work predicts that adhesion is a powerful mechanism for both positive and negative selection within the microbiota. We discuss molecules-mucus glycans and IgA-that affect microbe adhesion and identify testable predictions of the adhesion-as-selection model. PMID:27053168

  11. Theory of adhesion: Role of surface roughness

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.; Scaraggi, M.

    2014-09-01

    We discuss how surface roughness influences the adhesion between elastic solids. We introduce a Tabor number which depends on the length scale or magnification, and which gives information about the nature of the adhesion at different length scales. We consider two limiting cases relevant for (a) elastically hard solids with weak (or long ranged) adhesive interaction (DMT-limit) and (b) elastically soft solids with strong (or short ranged) adhesive interaction (JKR-limit). For the former cases we study the nature of the adhesion using different adhesive force laws (F ˜ u-n, n = 1.5-4, where u is the wall-wall separation). In general, adhesion may switch from DMT-like at short length scales to JKR-like at large (macroscopic) length scale. We compare the theory predictions to results of exact numerical simulations and find good agreement between theory and simulation results.

  12. Adhesive mechanisms in cephalopods: a review.

    PubMed

    von Byern, Janek; Klepal, Waltraud

    2006-01-01

    Several genera of cephalopods (Nautilus, Sepia, Euprymna and Idiosepius) produce adhesive secretions, which are used for attachment to the substratum, for mating and to capture prey. These adhesive structures are located in different parts of the body, viz. in the digital tentacles (Nautilus), in the ventral surface of the mantle and fourth arm pair (Sepia), in the dorsal epidermis (Euprymna), or in the dorsal mantle side and partly on the fins (Idiosepius). Adhesion in Sepia is induced by suction of dermal structures on the mantle, while for Nautilus, Euprymna and Idiosepius adhesion is probably achieved by chemical substances. Histochemical studies indicate that in Nautilus and Idiosepius secretory cells that appear to be involved in adhesion stain for carbohydrates and protein, whilst in Euprymna only carbohydrates are detectable. De-adhesion is either achieved by muscle contraction of the tentacles and mantle (Nautilus and Sepia) or by secretion of substances (Euprymna). The de-adhesive mechanism used by Idiosepius remains unknown. PMID:17110356

  13. Adhesion effects in contact interaction of solids

    NASA Astrophysics Data System (ADS)

    Goryacheva, Irina; Makhovskaya, Yulya

    2008-01-01

    An approach to solving problems of the interaction of axisymmetric elastic bodies in the presence of adhesion is developed. The different natures of adhesion, i.e. capillary adhesion, or molecular adhesion described by the Lennard-Jones potential are examined. The effect of additional loading of the interacting bodies outside the contact zone is also investigated. The approach is based on the representation of the pressure outside the contact zone arising from adhesion by a step function. The analytical solution is obtained and is used to analyze the influence of the form of the adhesion interaction potential, of the surface energy of interacting bodies or the films covering the bodies, their shapes (parabolic, higher power exponential function), volume of liquid in the meniscus, density of contact spots, of elastic modulus and the Poisson ratio on the characteristics of the interaction of the bodies in the presence of adhesion. To cite this article: I. Goryacheva, Y. Makhovskaya, C. R. Mecanique 336 (2008).

  14. Adhesive mechanisms in cephalopods: a review.

    PubMed

    von Byern, Janek; Klepal, Waltraud

    2006-01-01

    Several genera of cephalopods (Nautilus, Sepia, Euprymna and Idiosepius) produce adhesive secretions, which are used for attachment to the substratum, for mating and to capture prey. These adhesive structures are located in different parts of the body, viz. in the digital tentacles (Nautilus), in the ventral surface of the mantle and fourth arm pair (Sepia), in the dorsal epidermis (Euprymna), or in the dorsal mantle side and partly on the fins (Idiosepius). Adhesion in Sepia is induced by suction of dermal structures on the mantle, while for Nautilus, Euprymna and Idiosepius adhesion is probably achieved by chemical substances. Histochemical studies indicate that in Nautilus and Idiosepius secretory cells that appear to be involved in adhesion stain for carbohydrates and protein, whilst in Euprymna only carbohydrates are detectable. De-adhesion is either achieved by muscle contraction of the tentacles and mantle (Nautilus and Sepia) or by secretion of substances (Euprymna). The de-adhesive mechanism used by Idiosepius remains unknown.

  15. Spatial Diagnostics of Potential X-ray Remnants in Old Novae T Aur and DK Lac

    NASA Astrophysics Data System (ADS)

    Drake, Jeremy

    2013-09-01

    We propose 5 and 3 ks ACIS-S snapshots of potentially extended X-ray remnants of two old classical novae, T Aur and DK Lac. They are the likely counterparts of X-ray sources discovered in our Swift survey of old classical novae, and each target has a spatially-resolved optical remnant with a size of order arcseconds. The additional short Chandra snapshots will confirm or reject the tentative Swift identifications through pinpoint astrometry, and will distinguish between extended remnant emission or rejuvenated accretion. Both are important for understanding binary evolution and also potential post-outburst hibernation, while detection of extended emission will represent extremely rare additions to the exclusive club of X-ray emitting classical nova remnants.

  16. Pair of bollards and remnant seawall of Pan American Airways/Naval ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Pair of bollards and remnant seawall of Pan American Airways/Naval Air Transport Service/destroyer base site. View facing north. - U.S. Naval Base, Pearl Harbor, Pearl City Peninsula, Pearl City, Honolulu County, HI

  17. Two-temperature models of old supernova remnants with ion and electron thermal conduction

    NASA Technical Reports Server (NTRS)

    Cui, Wei; Cox, Donald P.

    1992-01-01

    To investigate the potential effects thermal conduction may have on the evolution of old supernova remnants, we present the results of 1D (spherically symmetric) numerical simulations of a remnant in a homogeneous interstellar medium for four different cases: (1) without thermal conduction; (2) with both electron and ion thermal conduction assuming equal temperatures; (3) with electron thermal conduction only, following electron and ion temperatures separately; and (4) with both electron and ion thermal conduction following separate temperatures. We followed the entire evolution until the completion of the remnant bubble collapse. Our most significant result is that in remnant evolution studies concerned principally with either the shell or bubble evolution at late times, reasonable results are obtained with single-temperature models. When the electron and ion temperatures are followed separately, however, ion thermal conduction cannot safely be ignored.

  18. Satellite Sees Remnants from Hurricane Patricia Affecting Southern U.S.

    NASA Video Gallery

    This 21 second animation of infrared and visible imagery from NOAA's GOES-East satellite from Oct. 24-26 shows the remnants of Hurricane Patricia move through the Gulf of Mexico and Gulf Coast Stat...

  19. Expansion of Kes 73, a shell supernova remnant containing a magnetar

    NASA Astrophysics Data System (ADS)

    Borkowski, Kazimierz

    2014-09-01

    Formation and evolution of highly magnetized neutron stars (magnetars) remain poorly understood. We can learn about magnetars by studying their remnants. Kes 73 is a young supernova remnant containing a magnetar. But basic properties of Kes 73, including its age, remain poorly known. We propose a third-epoch observation of Kes 73 with Chandra. When combined with the 2000 and 2006 observations, this will allow for determination of the remnant's age through expansion rate measurements. We will also search for spatial variations in expansion rate that will help in understanding of the remnant's dynamics. New observations will also be used to determine abundances of heavy-element supernova ejecta, placing further constraints on the supernova that produced Kes 73.

  20. Are supernova remnants quasi-parallel or quasi-perpendicular accelerators

    NASA Technical Reports Server (NTRS)

    Spangler, S. R.; Leckband, J. A.; Cairns, I. H.

    1989-01-01

    Observations of shock waves in the solar system which show a pronounced difference in the plasma wave and particle environment depending on whether the shock is propagating along or perpendicular to the interplanetary magnetic field are discussed. Theories for particle acceleration developed for quasi-parallel and quasi-perpendicular shocks, when extended to the interstellar medium suggest that the relativistic electrons in radio supernova remnants are accelerated by either the Q parallel or Q perpendicular mechanisms. A model for the galactic magnetic field and published maps of supernova remnants were used to search for a dependence of structure on the angle Phi. Results show no tendency for the remnants as a whole to favor the relationship expected for either mechanism, although individual sources resemble model remnants of one or the other acceleration process.