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Sample records for karin persson waller

  1. Superculture? Thoughts Prompted by Roland S. Persson's Essay

    ERIC Educational Resources Information Center

    Tebbs, Trevor J.

    2012-01-01

    The author finds Roland S. Persson's (2012a) paper to be timely, fascinating, important and powerful. At risk of mixing metaphors, it provides much food for thought and a penetrating lens through which all those vested in the optimal realisation of human potential would be prudent to review their own perceptions, boundaries of belief and…

  2. Photometry of Karin family asteroids

    NASA Astrophysics Data System (ADS)

    Hahn, G.; Mottola, S.; Sen, A. K.; Harris, A. W.; Kührt, E.; Mueller, M.

    2006-12-01

    We have performed photometric observations in the V-band of two asteroids belonging to the Karin asteroid family, (11728) Einer and (93690) 2000 VE21 , using the 2-m Himalayan Chandra Telescope, Hanle and 2k ×4k pixels CCD imager. We obtained measurements during two nights (November 25 and 26, 2005) which enabled information on the rotational periods and the lightcurve amplitudes of the asteroids to be derived. In addition, we derived the absolute magnitudes H, improving previously published values. These observations were performed to complement the IR observations obtained for a set of Karin family asteroids with the Spitzer space telescope.

  3. 832 Karin: Absence of rotational spectral variations

    NASA Astrophysics Data System (ADS)

    Vernazza, Pierre; Rossi, Alessandro; Birlan, Mirel; Fulchignoni, Marcello; Nedelcu, Alin; Dotto, Elisabetta

    2007-11-01

    832 Karin is the largest member of the young Karin cluster that formed 5.75±0.05 Myr ago in the outer main belt. Surprisingly, recent near-IR spectroscopy measurements [Sasaki, T., Sasaki, S., Watanabe, J., Sekiguchi, T., Yoshida, F., Kawakita, H., Fuse, T., Takato, N., Dermawan, B., Ito, T., 2004. Astrophys. J. 615 (2), L161-L164] revealed that Karin's surface shows different colors as a function of rotational phase. It was interpreted that 832 Karin shows us the reddish space-weathered exterior surface of the parent body as well as an interior face, which has not had time to become space-weathered. This result is at odds with recent results including seismic and geomorphic modeling, modeling of the Karin cluster formation and measurements of the space weathering rate. Consequently, we aimed to confirm/infirm this surprising result by sampling Karin's spectrum well throughout its rotation. Here, we present new visible (0.45-0.95 μm) and near-infrared (0.7-2.5 μm) spectroscopic observations of 832 Karin obtained in January and April 2006, covering most of Karin's longitudes. In the visible range, we find that Karin shows no rotational spectral variations. Similarly, we find that Karin exhibits very little (to none) spectral variations with rotation in the near-IR range. Our results imply that 832 Karin has a homogeneous surface, in terms of composition and surface age. Our results also imply that the impact that generated the family refreshed entirely Karin's surface, and probably the surfaces of all members.

  4. The Spin Vector of (832) Karin

    NASA Astrophysics Data System (ADS)

    Slivan, Stephen M.; Molnar, L. A.

    2010-10-01

    We observed rotation lightcurves of Koronis family and Karin cluster member (832) Karin during its four consecutive apparitions in 2006-2009, and combined the new observations with previously published lightcurves to determine its spin vector orientation and preliminary model shape. Karin is a prograde rotator with a period of 18.352 h, spin obliquity near 41°, and pole ecliptic longitude near either 51° or 228°. Although the two ambiguous pole solutions are near the clustered pole solutions of four Koronis family members whose spins are thought to be trapped in a spin-orbit resonance (Vokrouhlický et al., 2003), Karin does not seem to be trapped in the resonance; this is consistent with the expectation that the 6 My age of Karin (Nesvorný et al., 2002) is too young for YORP torques to have modified its spin since its formation. The spin vector and shape results for Karin will constrain family formation models that include spin properties, and we discuss the Karin results in the context of the other members of the Karin cluster, the Karin parent body, and the parent body's siblings in the Koronis family.

  5. Drawings of fossils by Robert Hooke and Richard Waller

    PubMed Central

    Kusukawa, Sachiko

    2013-01-01

    The drawings of fossils by Robert Hooke and Richard Waller that were the basis of the engravings in Hooke's Posthumous works (1705) are published here for the first time. The drawings show that both Hooke and Waller were proficient draftsmen with a keen eye for the details of petrified objects. These drawings provided Hooke with a polemic edge in making the case for the organic origins of ‘figured stones’.

  6. Spitzer Survey of the Karin Cluster Asteroids

    NASA Astrophysics Data System (ADS)

    Harris, Alan W.; Mueller, M.; Lisse, C.; Cheng, A.; Osip, D.

    2007-10-01

    The Karin cluster is one of the youngest known families of main-belt asteroids, dating back to a collisional event only 5.8 Myr ago. Using the Spitzer Space Telescope we have sampled the thermal continua of 17 Karin cluster asteroids, down to the smallest members discovered so far, in order to derive accurate sizes and study the physical properties of their surfaces. The albedos of the observed Karins appear to be very similar. The albedos, pv, have a mean of 0.17 and a standard deviation of 0.04, compared to pv = 0.15 ± 0.05 for 832 Karin itself (for H = 11.2 ± 0.3). The derived diameters range from 20 km for 832 Karin to 1.9 km for 93690, with uncertainties of 10%. The Karins data show no evidence of albedo dependence on size, and the small range of albedos is consistent with all program targets being S-type bodies. There is some evidence for higher values of thermal inertia amongst the smaller family members, which may be indicative of coarser regolith. These results are preliminary, pending outstanding Spitzer observations and further analysis. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.

  7. 832 Karin Shows No Rotational Spectral Variations

    NASA Astrophysics Data System (ADS)

    Chapman, Clark R.; Enke, B.; Merline, W. J.; Nesvorny, D.; Tamblyn, P.; Young, E. F.

    2006-09-01

    Sasaki et al. (2004, 2005) claimed that 832 Karin, the brightest member of the very young (5.75 Myr) Karin cluster of the Koronis family, shows dramatically different colors as a function of rotational phase. It was interpreted that Karin is a fragment of the recently broken-up asteroid, showing the reddish space-weathered exterior surface of the precursor asteroid as well as an interior face, which has not had time to become space-weathered. On five nights during UT 7-14 January 2006, we observed Karin with the SpeX instrument, 0.8-2.5 microns, on the IRTF. We sampled its spectrum well throughout its rotation. We analyzed the data in 50 deg. intervals of rotational longitude; some longitudes were sampled during two different nights. We find that Karin exhibits minimal spectral variations with rotation, certainly nothing of the magnitude reported by Sasaki et al. Since our data resemble Sasaki et al.'s "blue" and "green" sets, we suggest that their "red" set is spurious. Indeed, it is difficult to understand how the reported color change could have occurred during such a modest interval ( 4%) of rotational longitude. (Note that we have not determined Karin's pole position nor the phase of the Sasaki et al. data within our own coverage, so the refutation of dramatic color change is not absolutely secure.) Karin and its family members are not quite as red as typical S-types, yet have shallow absorption bands. Perhaps the space-weathering process affecting these young asteroids has had time to reduce spectral contrast, but has not operated long enough to redden them -- an intermediate case of space weathering, which has gone to completion for older main-belt asteroids of these sizes. Supported by the NASA Planetary Astronomy Program. T. Sasaki et al. 2004. ApJ 615, L161-L164; T. Sasaki et al. 2005. LPSC XXXVI, 1590.pdf.

  8. Spectroscopic characterization of the Karin family

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Fulchignoni, M.; Birlan, M.; Dotto, E.; Rossi, A.; Fornasier, S.; Marzari, F.; Nesvorny, D.

    2005-08-01

    The Karin asteroidal family was firstly identified by Nesvorny et al. (2002, Nature 417) who numerically integrated the orbits of 39 known members. More recently Nesvorny and Bottke (2004) analyzed a wider sample of objects and, taking into account also the Yarkovsky effect, identified the common origin of 90 family members at 5.75±0.05 Myr in the past. This is an exceptionally young age for an asteroid family. In fact, other known families are thought to be much older, 100 Myr to Gyrs old. We carried out visible and near-infrared spectroscopy of several members of the Karin family. We observed 5 member of the Karin family on November 2003 using the IRTF telescope. These data confirm that 832 Karin is an S-type asteroid (as indicated by Binzel, private communication), characterized by strong absorption features of olivine and pyroxene at about 1 and 2 μ m. Visible spectra for 20 objects were later obtained in December, 2004 with EMMI/NTT (ESO, La Silla) and with MOS/CFHT (Mauna Kea, Hawaii). Fifteen of these objects (832 Karin among them), have S-type spectra with the maximum of each spectra located at a very similar wavelength. This result sustain the hypothesis of a common origin. Five other spectra obtained seem rather primitive (B,C types). We analysed the spectra of the Karin cluster in the context of the Koronis family. This analysis reveals that the spectra are less red than those of the Koronis members. Moreover, we can interpret them as less mature surfaces. Finally, we made an interpretation of the surface composition of 832 Karin, using the Shkuratov scattering model.

  9. Culture, Globalisation and the Study of Giftedness: Reflections on Persson's Analysis and Recommendations for Future Research

    ERIC Educational Resources Information Center

    Foreman, Jennifer; Renzulli, Joseph

    2012-01-01

    Dr. Persson's (2012a) target article addresses a number of key points that will greatly impact the study of giftedness, gifted education, and talent development in the "flat" world of the 21st century and beyond. Research in these areas needs to continually reflect upon changes in the social world outside its narrow purview to validate its…

  10. Policy, Practice in Giftedness, and Research Methodologies: Response to Roland S. Persson's Article

    ERIC Educational Resources Information Center

    Matthews, Dona J.

    2012-01-01

    The author finds the target article "Cultural Variation and Dominance in a Globalised Knowledge Economy" to be a thoughtful exploration of an important topic for all social scientists, certainly including those who study gifted development and education. Roland S. Persson (2012a) raises many questions about policy and practice in giftedness…

  11. Spin vectors in the Koronis family: III. (832) Karin

    NASA Astrophysics Data System (ADS)

    Slivan, Stephen M.; Molnar, Lawrence A.

    2012-08-01

    Studies of asteroid families constrain models of asteroid collisions and evolution processes, and the Karin cluster within the Koronis family is among the youngest families known (Nesvorný, D., Bottke, Jr., W.F., Dones, L., Levison, H.F. [2002]. Nature 417, 720-722). (832) Karin itself is by far the largest member of the Karin cluster, thus knowledge of Karin's spin vector is important to constrain family formation and evolution models that include spin, and to test whether its spin properties are consistent with the Karin cluster being a very young family. We observed rotation lightcurves of Karin during its four consecutive apparitions in 2006-2009, and combined the new observations with previously published lightcurves to determine its spin vector orientation and preliminary model shape. Karin is a prograde rotator with a period of (18.352 ± 0.003) h, spin obliquity near (42 ± 5)°, and pole ecliptic longitude near either (52 ± 5)° or (230 ± 5)°. The spin vector and shape results for Karin will constrain models of family formation that include spin properties; in the meantime we briefly discuss Karin's own spin in the context of those of other members of the Karin cluster and the parent body's siblings in the Koronis family.

  12. Lightcurves of the Karin family asteroids

    NASA Astrophysics Data System (ADS)

    Yoshida, Fumi; Ito, Takashi; Dermawan, Budi; Nakamura, Tsuko; Takahashi, Shigeru; Ibrahimov, Mansur A.; Malhotra, Renu; Ip, Wing-Huen; Chen, Wen-Ping; Sawabe, Yu; Haji, Masashige; Saito, Ryoko; Hirai, Masanori

    2016-05-01

    The Karin family is a young asteroid family formed by an asteroid breakup 5.8 Myr ago. Since the members of this family probably have not experienced significant orbital or collisional evolution yet, it is possible that they still preserve properties of the original family-forming event in terms of their spin state. We carried out a series of photometric observations of the Karin family asteroids, and here we report on the analysis of the lightcurves including the rotation period of eleven members. The mean rotation rate of the Karin family members turned out to be much lower than those of near-Earth asteroids or small main belt asteroids (diameter D < 12 km), and even lower than that of large main belt asteroids (D > 130 km). We investigated a correlation between the peak-to-trough variation and the rotation period of the eleven Karin family asteroids, and found a possible trend that elongated members have lower spin rates, and less elongated members have higher spin rates. However, this trend has to be confirmed by another series of future observations.

  13. Karin cluster formation by asteroid impact

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Enke, Brian L.; Bottke, William F.; Durda, Daniel D.; Asphaug, Erik; Richardson, Derek C.

    2006-08-01

    Insights into collisional physics may be obtained by studying the asteroid belt, where large-scale collisions produced groups of asteroid fragments with similar orbits and spectra known as the asteroid families. Here we describe our initial study of the Karin cluster, a small asteroid family that formed 5.8±0.2 Myr ago in the outer main belt. The Karin cluster is an ideal 'natural laboratory' for testing the codes used to simulate large-scale collisions because the observed fragments produced by the 5.8-Ma collision suffered apparently only limited dynamical and collisional erosion. To date, we have performed more than 100 hydrocode simulations of impacts with non-rotating monolithic parent bodies. We found good fits to the size-frequency distribution of the observed fragments in the Karin cluster and to the ejection speeds inferred from their orbits. These results suggest that the Karin cluster was formed by a disruption of an ≈33-km-diameter asteroid, which represents a much larger parent body mass than previously estimated. The mass ratio between the parent body and the largest surviving fragment, (832) Karin, is ≈0.15-0.2, corresponding to a highly catastrophic event. Most of the parent body material was ejected as fragments ranging in size from yet-to-be-discovered sub-km members of the Karin cluster to dust grains. The impactor was ≈5.8 km across. We found that the ejections speeds of smaller fragments produced by the collision were larger than those of the larger fragments. The mean ejection speeds of >3-km-diameter fragments were ≈10 ms. The model and observed ejection velocity fields have different morphologies perhaps pointing to a problem with our modeling and/or assumptions. We estimate that ˜5% of the large asteroid fragments created by the collision should have satellites detectable by direct imaging (separations larger than 0.1 arcsec). We also predict a large number of ejecta binary systems with tight orbits. These binaries, located in the

  14. Risk, Russian-roulette and lotteries: Persson and Savulescu on moral enhancement.

    PubMed

    Gunson, Darryl; McLachlan, Hugh

    2013-11-01

    The literature concerning the possibility and desirability of using new pharmacological and possible future genetic techniques to enhance human characteristics is well-established and the debates follow some well-known argumentative patterns. However, one argument in particular stands out and demands attention. This is the attempt to tie the moral necessity of moral enhancement to the hypothesised risks that allowing cognitive enhancement will bring. According to Persson and Savulescu, cognitive enhancement should occur only if the risks they think it to poses are mitigated by moral enhancement. By this they mean the compulsory and universal amplification of the disposition of altruism and the inflation of our sense of fairness, by chemical and/or genetic means. Their claim is important, intriguing and unsettling. This paper focuses on three central, but relatively neglected, features of their argument. First, there is a pernicious ambiguity in the language of 'risk' used by Persson and Savulescu where they tend to conflate 'risk' and 'uncertainty'. Second, their use of the lottery analogy to render their position more plausible is unconvincing. It tends to distort rather than illuminate the relevant considerations. Third, Persson and Savulescu do not adequately take into account the social and individual benefits that enhancing cognition could have. If they did, it would be apparent that those benefits alone would outweigh the considerations used to justify accompanying CE with ME. PMID:23277383

  15. The Black American Press and the New Manifest Destiny: The Waller Affair

    ERIC Educational Resources Information Center

    Woods, Randall B.

    1977-01-01

    In 1895 the United States and France became involved in a dispute concerning the arrest and imprisonment of one John L. Waller, a black American who dared to challenge French imperialism in Madagascar. The black press, perhaps at the height of its power and influence, reacted vigorously to Waller and his goals, and to the Cleveland…

  16. An "Immanent" Social Class Effect on Participation in Higher Education? A Rejoinder to Harrison and Waller

    ERIC Educational Resources Information Center

    Noble, John; Davies, Peter

    2010-01-01

    This article responds to criticisms, put forward by Harrison and Waller in this issue, of an earlier paper by Noble and Davies. In particular, we argue that our interpretation of earlier quantitative research is correct, that Harrison and Waller have misconstrued the purpose of our previous paper and the analysis it contains, and that they…

  17. Age of the Karin Cluster of Asteroids

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Knezevic, Z.; Cellino, A.; Dell'Oro, A.

    2005-12-01

    The Karin Cluster, the youngest known asteroid family, was formed by a catastrophic disruption event about 5.8 million years ago. We have undertaken extensive numerical orbital integrations to confirm and refine the cluster age and to refine cluster membership. The Karin Cluster is important because its members have a precisely known, common formation age, enabling new tests of models for asteroid fragmentation, orbital evolution, surface space weathering, and regolith formation and evolution, but it is necessary to distinguish cluster members from background objects in a densely populated region of the main asteroid belt, close to the center of the Koronis family. We have performed full orbital integrations of 122 numbered asteroids backwards in time over the last 10 million years, to calculate filtered mean Keplerian elements at 500 year time resolution. These calculations show that the age of the Karin cluster is 5.7635 ± 0.0005 Myr, consistent with prior work. The calculations also confirm 54 numbered asteroids as cluster members, and they identify as interlopers some objects included in previous cluster lists.

  18. Revealing Additional Dimensions of Globalisation and Cultural Hegemony: A Response to Roland S. Persson's Call for Cultural Sensitivity in Gifted Studies

    ERIC Educational Resources Information Center

    Ambrose, Don

    2012-01-01

    In this commentary, the author finds the interdisciplinary approach of Roland S. Persson's (2012a) target article refreshing. Persson's (2012a) additional emphases on ethnocentricity, cultural bias and strong threads of influence from the global economy also are helpful. They shed light on some strong contextual influences that shape the…

  19. Color Variation of a Very Young Asteroid, Karin

    NASA Astrophysics Data System (ADS)

    Ito, Takashi; Yoshida, Fumi

    2007-02-01

    We present current results of our long-term campaign to make photometric observations of the new-born Karin family asteroids, especially those of (832) Karin. Karin, an S-type main-belt asteroid, is the largest member of the Karin family. This asteroid is likely a large fragment of a disruption event in the main asteroid belt that occurred about 5.8 million years ago. We obtained multi-color photometric observations of this asteroid in 2003 and 2004. We have reported a potential surface color variation of this asteroid, which indicates the existence of both mature and fresh surfaces on it. However, as of 2004 September, this asteroid apparently does not show a strong surface color difference, which might give us some insight into its spin axis orientation and shape. This is quite an interesting result, but it has to be confirmed by future observations.

  20. Physical characterization of the Karin family

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Birlan, M.; Rossi, A.; Dotto, E.; Nesvorny, D.; Brunetto, R.; Fornasier, S.; Fulchignoni, M.; Renner, S.

    2006-12-01

    Aims.The Karin cluster is a small asteroid family that formed 5.8 ± 0.2 Myr ago in the outer main belt. This is an exceptionally young age for an asteroid family. To investigate the composition and homogeneity of the members of this family, we started a spectroscopic survey in the visible and in the near-IR. Methods: .We observed 24 Karin asteroid members in the visible and 6 members in the near-IR. Results: .In the visible range, all the objects share the same characteristics: a maximum around λ = 0.75 μm, and a spectral slope spanning a continuous but limited range; in the NIR, our spectra show a similar behaviour. Our results suggest global homogeneity of the parent body and none of the investigated objects seems to be an interloper. These results are consistent with the dynamical hypothesis of a common origin. Finally, the range of spectral slopes is similar with the range of slopes for OC meteorites. We interpret this result as an indication of a low degree of spatial alteration for the observed surfaces. This result is coherent with the young age of the family.

  1. An experimental 'Life' for an experimental life: Richard Waller's biography of Robert Hooke (1705).

    PubMed

    Moxham, Noah

    2016-03-01

    Richard Waller's 'Life of Dr Robert Hooke', prefixed to his edition of Hooke's Posthumous Works (1705), is an important source for the life of one of the most eminent members of the early Royal Society. It also has the distinction of being one of the earliest biographies of a man of science to be published in English. I argue that it is in fact the first biography to embrace the subject's natural-philosophical work as the centre of his life, and I investigate Waller's reasons for adopting this strategy and his struggle with the problem of how to represent an early experimental philosopher in print. I suggest that Waller eschews the 'Christian philosopher' tradition of contemporary biography - partly because of the unusually diverse and fragmentary nature of Hooke's intellectual output - and draws instead upon the structure of the Royal Society's archive as a means of organizing and understanding Hooke's life. The most quoted phrase from Waller's biography is that Hooke became 'to a crime close and reserved' in later life; this essay argues that Waller's biographical sketch was fashioned in order to undo the effects of that reserve. In modelling his approach very closely on the structure of the society's records he was principally concerned with making Hooke's work and biography accessible, intelligible and useful to the fellowship in a context familiar to them, a context which had provided the institutional framework for most of Hooke's adult life. I argue that Waller's 'Life' was also intended to make the largest claims for Hooke's intellectual standing that the author dared in the context of the enmity between Hooke and Isaac Newton once the latter became president of the Royal Society. However, I also adduce fresh manuscript evidence that Waller actually compiled, but did not publish, a defence of Hooke's claim to have discovered the inverse square law of gravity, allowing us to glimpse a much more assertive biography of Hooke than the published version. PMID

  2. Temperature dependence of Debye-Waller factor in dye-doped polymers

    NASA Astrophysics Data System (ADS)

    Saikan, S.; Imaoka, A.; Kanematsu, Y.; Sakoda, K.; Kominami, K.; Iwamoto, M.

    1990-02-01

    The temperature dependence of the Debye-Waller factor in dye-doped polymers has been investigated with femtosecond accumulated photon echo. The superiority of polyvinyl alcohol as the host polymer for the optical-memory material is ascribed to the higher phonon sideband frequency in this sample. It is pointed out that the temperature dependence of the Debye-Waller factor, in particular the phonon sideband frequency, is of fundamental importance to finding out the best polymer for high-temperature optical memory based on photochemical hole burning.

  3. John Dewey and the Question of Race: The Fight for Odell Waller

    ERIC Educational Resources Information Center

    Stack, Sam F., Jr.

    2009-01-01

    In an attempt to better understand the complexity of American racism and democracy, this paper explores racism through the plight of an African American sharecropper, Odell Waller, and the reaction and involvement of John Dewey, America's most liberal democratic philosopher of the 20th century. This exploration delves into the nature of American…

  4. Willard Waller's Sociology of Teaching Reconsidered: "What Does Teaching Do to Teachers?"

    ERIC Educational Resources Information Center

    Pajak, Edward F.

    2012-01-01

    Willard Waller's (1932/1976) classic account of what teaching does to teachers is examined through the lens of psychoanalytic theory in conjunction with Ovid's myth of Narcissus. Parallel themes within the two texts are analyzed and interpreted as suggesting that narcissistic psychological processes played a part in distorting teachers'…

  5. VizieR Online Data Catalog: Properties of asteroids in Karin cluster (Carruba+, 2016)

    NASA Astrophysics Data System (ADS)

    Carruba, V.; Nesvorny, D.; Vokrouhlicky, D.

    2016-07-01

    Many new asteroids have been discovered since the last dynamical analysis of the Karin cluster. Here we repeat the analysis of Nesvorny & Bottke (2004Icar..170..324N) with an orbital catalog that contains nearly seven times more asteroids than there were available back in 2004. We revise the Karin family membership by applying the usual clustering method on the new orbital catalog. The taxonomical and albedo interlopers are eliminated. We then apply a more stringent criterion of the Karin family membership by requiring that orbits converged with each other ~5.75Myr ago. In Table1, we report the list of 480 identified Karin cluster members. (1 data file).

  6. Calculation of the Debye-Waller factor for atom-surface scattering: He on Ag(111)

    NASA Astrophysics Data System (ADS)

    Idiodi, J.; Bortolani, V.; Franchini, A.; Santoro, G.; Celli, V.

    1987-04-01

    By a consistent application of the distorted-wave Born approximation, the Debye-Waller exponent for the scattering of He atoms from the Ag(111) surface is directly computed. When diffraction is negligible, as in this case, the decrease in specular intensity is simply obtained by summing the scattering due to all possible one-phonon processes. Using one-phonon computed intensities that agree with experiment along high-symmetry directions of the surface Brillouin zone, we find that the computed Debye-Waller exponent agrees with experiment and corresponds to an effective Debye temperature of 241 K. All corrections to the eikonal-type formula, 2W=4p2z, are automatically included. In particular, the contribution of phonons with high parallel momentum is sharply cut off.

  7. Self-consistent Debye-Waller factors of the electron solid on liquid helium

    NASA Astrophysics Data System (ADS)

    Namaizawa, H.

    1980-05-01

    Based on the self-consistent field formalism we propose a shear-mode self-consistency for the high-frequency Debye-Waller factors (HFDWF) of the electron solid bound on a free surface of liquid helium. Our results are qualitatively in agreement with the empirical DW factor determined by Fisher, Halperin, and Platzman with the experiment of Grimes and Adams. We also report the analysis of the HFDWF according to the Lindemann law.

  8. Who invented the dichotomous key? Richard Waller's watercolors of the herbs of Britain.

    PubMed

    Griffing, Lawrence R

    2011-12-01

    On 27 March 1689, Richard Waller, Fellow and Secretary of the Royal Society presented his "Tables of the English Herbs reduced to such an order, as to find the name of them by their external figures and shapes" to his assembled colleagues at a meeting of the Royal Society. These tables were developed for the novice by being color images, composed in pencil and watercolor, of selected plants and their distinguishing characteristics. The botanical watercolors for the tables are now a Turning-the-Pages document online on the website of the Royal Society. However, for the past 320 years, the scientific context for the creation of these outstanding botanical watercolors has remained obscure. These tables were developed by Waller as an image-based dichotomous key, pre-dating by almost 100 years the text-based dichotomous keys in the first edition of Flora Française (1778) by Jean Baptiste Lamarck, who is generally given priority for the development of the dichotomous key. How these large folio images were arranged to illustrate a dichotomous key is unknown, but an arrangement based on Waller's description is illustrated here as leaf-ordering for the separate hierarchical clusters (tables). Although only 24 species of watercolored dicot herbs out of a total of 65 in the set of watercolors (the others being monocots) are used in these tables, they are a "proof of concept", serving as models upon which a method is based, that of using a key composed of dichotomous choices for aiding identification. PMID:22074776

  9. Young Asteroid 832 Karin shows no rotational spectral variations

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Enke, B.; Merline, W. J.; Tamblyn, P.; Nesvorný, D.; Young, E. F.; Olkin, C.

    2007-11-01

    We have made near-IR spectral observations of the very young (5.75 Myr) S-type asteroid 832 Karin, well sampled in rotational phase over its 18.35-h period. We find no significant variations in its reflectance spectrum. Karin, the brightest member of the Karin cluster (a sub-family of the larger, older Koronis dynamical family), was shown to be exceptionally young by Nesvorný et al. [Nesvorný, D., Bottke, W.F., Dones, L., Levison, H., 2002. Nature 417, 720-722], using backward numerical integration of orbital elements of cluster members. Their precise dating of the collisional breakup gives us an opportunity, for the first time and without age-dating of physical samples, to monitor time-evolution of processes, like space weathering, that operate on timescales of ˜1-10 Myr. Sasaki et al. [Sasaki, T., Sasaki, S., Watanabe, J., Sekiguchi, T., Yoshida, F., Kawakita, H., Fuse, T., Takato, N., Dermawan, B., Ito, T., 2004. Astrophys. J. 615, L161-L164; Sasaki, T., Sasaki, S., Watanabe, J., Sekiguchi, T., Yoshida, F., Ito., T., Kawakita, H., Fuse, T., Takato, N., Dermawan, B., 2005. Lunar Planet. Sci. XXXVI. Abstract #1590] had made similar measurements of Karin, although more sparsely sampled than ours, and claimed dramatically different colors as a function of rotational phase. Sasaki et al. interpreted their data to be showing the reddish, space-weathered exterior surface of the precursor asteroid, as well as an interior face, which had not had time to become space-weathered. On five nights over 2006 January 7-14 UT, we observed Karin with the SpeX (0.8-2.5 μm) spectrometer of the IRTF. We analyze data in 30° intervals of rotational longitude, some of which we sampled on two different nights. The spectra are consistent with little or no spectral variation as the asteroid rotates; certainly there are no changes as large as previously reported. The previous observations were probably spurious. Our average spectrum resembles the "blue" spectrum of Sasaki et al., which

  10. A Surrogate for Debye-Waller Factors from Dynamic Stokes Shifts

    PubMed Central

    Zhong, Qin; Johnson, Jerainne; Aamer, Khaled A.; Tyagi, Madhusudan

    2011-01-01

    We show that the short-time behavior of time-resolved fluorescence Stokes shifts (TRSS) are similar to that of the intermediate scattering function obtained from neutron scattering at q near the peak in the static structure factor for glycerol. This allows us to extract a Debye-Waller (DW) factor analog from TRSS data at times as short as 1 ps in a relatively simple way. Using the time-domain relaxation data obtained by this method we show that DW factors evaluated at times ≥ 40 ps can be directly influenced by α relaxation and thus should be used with caution when evaluating relationships between fast and slow dynamics in glassforming systems. PMID:21701673

  11. Measuring Order and the Debye-Waller Factor for Porous Arrays

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi

    2007-03-01

    We derive methods that explain how to quantify the amount of order in ``ordered'' and ``highly ordered'' porous arrays. Ordered arrays from bee honeycomb and several from the general field of nanoscience are compared. Accurate measures of the order in porous arrays are made using the discrete radial distribution function (RDF) and the Debye-Waller Factor (DWF) from 2-D discrete Fourier transforms calculated from the real-space data using MATLAB routines. Nanoporous anodized aluminum oxide, hexagonal arrays from functional materials, hexagonal arrays from nanosphere lithography, and arrays from block copolymer lithography (all taken from the literature) are compared to two-dimensional model systems. The DWF is normalized to the first harmonic and depends on N, the number of peaks in the fit for these finite arrays. We optimize N to the classical model for the DWF as a fit to reciprocal space K^2.

  12. The anomalous Debye-Waller factor and the fragility of glasses

    NASA Astrophysics Data System (ADS)

    Roland, C. M.; Ngai, K. L.

    1996-02-01

    The correlation between the magnitude of the Debye-Waller anomaly and the temperature dependence of the relaxation time and viscosity of glass-forming liquids (i.e., their fragility) is investigated using the coupling model of relaxation. The correlation is shown to be a natural consequence of the relationship between the noncooperative and intermolecularly cooperative relaxation times of the model. Specifically, the deviation of the mean squared displacement from a linear temperature dependency increases as the fragility (in the Angell sense) of the glass-forming liquid increases because more fragile glasses exhibit substantially more short-time, noncooperative relaxation. This latter fact arises from their shorter noncooperative relaxation times, as deduced from the coupling model.

  13. A newborn asteroid 832 Karin with old and new surfaces SUBARU spectroscopy

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho; Sasaki, Takanori; Watanabe, Jun-ichi; Yoshida, Fumi; Kawakita, Hideyo; Takato, Naruhisa; Dermawan, Budi; Fuse, Tetsuharu; Ito, Takashi; Sekiguchi, Tomohiko

    2006-01-01

    The mismatch between reflectance spectra of most common asteroids (S-type asteroids) and most common meteorites (ordinary chondrites) is thought to be caused by space weathering. Recent study of celestial mechanics has led to the discovery of a young group of S-type asteroids, "Karin cluster group", which is thought to be remnants of a collisional breakup only 5.8 million years ago. We performed near-infrared spectroscopy of the brightest asteroid 832 Karin among this cluster group. For different rotational phases of Karin, we derived different spectra such as reddened spectrum like that of S-type asteroid and unreddened spectrum like that of ordinary chondrites. These findings indicate that a part of Karin may retain spectrally mature surface of its parent body. Although Karin might have formed from gravitational accumulation from catastrophic collision of its parent body, there would be some color heterogeneity on its surface if Karin collected materials which derived the weathered surface of the parent body.

  14. A Robust Survey of the Physical Properties of the Karin Cluster Asteroids

    NASA Astrophysics Data System (ADS)

    Harris, Alan; Cheng, Andrew; Fitzsimmons, Alan; Hicks, Michael; Lisse, Carey; Lowry, Stephen; Mueller, Michael; Osip, Dave

    2005-06-01

    The Karin cluster is by far the youngest known family of main-belt asteroids, dating back to a collisional event only 5.8+/-0.2 Myr ago. We propose to sample the thermal continua of 17 Karin cluster asteroids of different sizes, down to the smallest members discovered so far, in order to derive accurate sizes and study the physical properties of their surfaces. Our aims include a study of trends in thermal inertia and albedo with size. The analysis will be based on sophisticated thermal models that will provide important insight into thermal inertia and regolith coverage. The widely used 'standard thermal model' leads to serious errors in thermal studies of small asteroids and is not adequate for a detailed study of the physical characteristics of Karin cluster members. The following questions are amongst those addressed by this program: 1. Are the distributions of sizes and albedos compatible with the Karin cluster being the result of a single catastrophic collision 5.8+/-0.2 Myr ago (Nesvorny et al., 2002)? 2. Are the sizes and thermal properties of the Karin-cluster members compatible with the claim of Nesvorny and Bottke (2004) that the Yarkovsky Effect is responsible for an apparent non-gravitational drift of their orbital motion? 3. Does the retention of a significant thermally insulating layer of regolith depend on asteroid size? If so, what are the consequences for modeling the Yarkovsky effect and the delivery of main-belt asteroids into near-Earth orbits? 4. Is there a correlation between albedo and size among the Karin cluster members similar to that evident for near-Earth asteroids in the same size range? If so, what are the consequences for models of age-dependent space weathering? (the Karin cluster members all have the same age).

  15. Search for anisotropy in the Debye-Waller factor of HCP solid (4)He.

    PubMed

    Barnes, Ashleigh L; Hinde, Robert J

    2016-02-28

    The properties of hexagonal close packed (hcp) solid (4)He are dominated by large atomic zero point motions. An accurate description of these motions is therefore necessary in order to accurately calculate the properties of the system, such as the Debye-Waller (DW) factors. A recent neutron scattering experiment reported significant anisotropy in the in-plane and out-of-plane DW factors for hcp solid (4)He at low temperatures, where thermal effects are negligible and only zero-point motions are expected to contribute. By contrast, no such anisotropy was observed either in earlier experiments or in path integral Monte Carlo (PIMC) simulations of solid hcp (4)He. However, the earlier experiments and the PIMC simulations were both carried out at higher temperatures where thermal effects could be substantial. We seek to understand the cause of this discrepancy through variational quantum Monte Carlo simulations utilizing an accurate pair potential and a modified trial wavefunction which allows for anisotropy. Near the melting density, we find no anisotropy in an ideal hcp (4)He crystal. A theoretical equation of state is derived from the calculated energies of the ideal crystal over a range of molar volumes from 7.88 to 21.3 cm(3), and is found to be in good qualitative agreement with experimental data. PMID:26931710

  16. Search for anisotropy in the Debye-Waller factor of HCP solid 4He

    NASA Astrophysics Data System (ADS)

    Barnes, Ashleigh L.; Hinde, Robert J.

    2016-02-01

    The properties of hexagonal close packed (hcp) solid 4He are dominated by large atomic zero point motions. An accurate description of these motions is therefore necessary in order to accurately calculate the properties of the system, such as the Debye-Waller (DW) factors. A recent neutron scattering experiment reported significant anisotropy in the in-plane and out-of-plane DW factors for hcp solid 4He at low temperatures, where thermal effects are negligible and only zero-point motions are expected to contribute. By contrast, no such anisotropy was observed either in earlier experiments or in path integral Monte Carlo (PIMC) simulations of solid hcp 4He. However, the earlier experiments and the PIMC simulations were both carried out at higher temperatures where thermal effects could be substantial. We seek to understand the cause of this discrepancy through variational quantum Monte Carlo simulations utilizing an accurate pair potential and a modified trial wavefunction which allows for anisotropy. Near the melting density, we find no anisotropy in an ideal hcp 4He crystal. A theoretical equation of state is derived from the calculated energies of the ideal crystal over a range of molar volumes from 7.88 to 21.3 cm3, and is found to be in good qualitative agreement with experimental data.

  17. Detection of the YORP Effect for Small Asteroids in the Karin Cluster

    NASA Astrophysics Data System (ADS)

    Carruba, V.; Nesvorný, D.; Vokrouhlický, D.

    2016-06-01

    The Karin cluster is a young asteroid family thought to have formed only ≃ 5.75 Myr ago. The young age can be demonstrated by numerically integrating the orbits of Karin cluster members backward in time and showing the convergence of the perihelion and nodal longitudes (as well as other orbital elements). Previous work has pointed out that the convergence is not ideal if the backward integration only accounts for the gravitational perturbations from the solar system planets. It improves when the thermal radiation force known as the Yarkovsky effect is accounted for. This argument can be used to estimate the spin obliquities of the Karin cluster members. Here we take advantage of the fast growing membership of the Karin cluster and show that the obliquity distribution of diameter D≃ 1{--}2 km Karin asteroids is bimodal, as expected if the YORP effect acted to move obliquities toward extreme values (0° or 180°). The measured magnitude of the effect is consistent with the standard YORP model. The surface thermal conductivity is inferred to be 0.07–0.2 W m‑1 K‑1 (thermal inertia ≃ 300{--}500 J m‑2 K‑1 s{}-1/2). We find that the strength of the YORP effect is roughly ≃ 0.7 of the nominal strength obtained for a collection of random Gaussian spheroids. These results are consistent with a surface composed of rough, rocky regolith. The obliquity values predicted here for 480 members of the Karin cluster can be validated by the light-curve inversion method.

  18. Elastic properties of collagen in bone determined by measuring the Debye-Waller factor.

    PubMed

    Sasaki, Naoki; Shirakawa, Hideki; Nozoe, Tsutomu; Furusawa, Kazuya

    2013-11-15

    Force constant values for thermal vibrational motion of a collagen molecule along the helix axis in tendon, completely demineralized bone (CDB), and partially demineralized bone (PDB) were estimated by determining the Debye-Waller factor (DW factor) for the diffracted X-ray intensity from these specimens. The DW factor for nominal value of 0.286nm meridional diffraction representing a period along the helical axis of a collagen molecule was measured. As the atomic scattering factor of mineral constituents is much larger than that of collagen, it is difficult to detect the diffraction from collagen in bone specimen. Therefore, PDB was used in this study. In order to compare obtained force constant value for CDB with mechanical properties of collagen in the literature, the value was translated into Young's modulus value using the cross-sectional area of a collagen molecule. In the case of collagen in PDB, i.e., collagen with the close presence of HAp mineral particles, as the DW factor of the diffracted intensity by hydroxyapatite (HAp) was considered to be negligible compared with that of collagen, the DW factor determined was interpreted as that of collagen molecule in PDB specimen. The force constant value obtained for collagen in PDB was significantly larger than that of collagen in CDB. This result was thought to be a manifestation of the hardening of collagen matrix in bone by HAp mineral particles and the first straightforward evidence for a difference in collagen properties depending on the presence of HAp mineral particles. The method employed in this study can be utilized for detecting mechanical properties of the individual constituents of composite materials. PMID:24090493

  19. Monte Carlo Simulation Using Johnson Potential on Gd-Mg Alloy for Debye-Waller Factor and Debye Temperature

    NASA Astrophysics Data System (ADS)

    Chitra, S.; Ramachandran, K.

    Monte Carlo simulation (MCS) on the thermal properties in Gd-Mg alloy becomes essential as there are only limited experiments available. A realistic Johnson potential is used to workout the specific heats for various temperatures and hence the Debye temperature. The results from the present simulation technique are very well compared with our shell model calculation. The need of better X-ray measurements for Debye-Waller factor and Debye temperature other than the measurements of Subadhra and Sirdeshmukh, is discussed in detail.

  20. Difference in Degree of Space Weathering on the Newborn Asteroid Karin

    NASA Astrophysics Data System (ADS)

    Sasaki, T.; Sasaki, S.; Watanabe, J. I.; Sekiguchi, T.; Yoshida, F.; Ito, T.; Kawakita, H.; Fuse, T.; Takato, N.; Dermawan, B.

    2005-03-01

    Here we report a near-infrared spectroscopy of the newborn asteroid Karin. For different rotational phases, we derived different spectra such as reddened spectrum like that of S- type asteroid and un-reddened spectrum like that of ordinary chondrite.

  1. Details of Recent Collisions of Asteroids 832 Karin and 158 Koronis

    NASA Astrophysics Data System (ADS)

    Molnar, Lawrence A.; Haegert, M. J.

    2009-09-01

    We present analysis of the membership and dynamics of two recently formed asteroid clusters: 832 Karin (5.72 My) and 158 Koronis (15.0 My). The unprecedented detail of both collisions (one catastrophic and one not) provides rigorous tests of asteroid collision models. We use the AstDyS catalog of analytic proper elements to identify asteroids with high quality orbits that are dynamically near the Karin cluster (873 objects), and use the OrbFit software to compute precise synthetic proper elements. We define a cut in five dimensional phase space to determine Karin membership. The key to an effective cut is the use of two linear combinations of elements: a combination of the longitudes that is independent of the Yarkovsky drift and a combination of eccentricity and drift-corrected semimajor axis. Karin cluster membership is increased to 387 objects, four times the previously published number. Highlights of analysis include a size-frequency distribution with significant curvature, and two clusters in the histogram of spin obliquities (inferred from the Yarkovsky drift of the longitudes). The latter is consistent with capture of the smallest members (diameters less than 2 km) in Slivan states. Removal of the Karin members from the sample reveals a previously unknown cluster of 151 objects resulting from a recent non-catastrophic collision with Koronis (which has 98.7% of the total mass). With an age of 15 My, individual longitudes have drifted by as much as 540 degrees due to the Yarkovsky effect, yet it remains possible to unwrap the angles and determine membership. Highlights of the analysis include final speeds relative to Koronis less than the escape speed and a pronounced preference for outflow directions in a small cone. The mass of the material launched below escape speed likely exceeds that of the escaped objects. Funded by a Kuiper endowment and a Calvin Research Fellowship.

  2. A survey of Karin cluster asteroids with the Spitzer Space Telescope

    NASA Astrophysics Data System (ADS)

    Harris, Alan W.; Mueller, Michael; Lisse, Carey M.; Cheng, Andrew F.

    2009-01-01

    The Karin cluster is one of the youngest known families of main-belt asteroids, dating back to a collisional event only 5.8±0.2 Myr ago. Using the Spitzer Space Telescope we have photometrically sampled the thermal continua (3.5-22 μm) of 17 Karin cluster asteroids of different sizes, down to the smallest members discovered so far, in order to make the first direct measurements of their sizes and albedos and study the physical properties of their surfaces. Our targets are also amongst the smallest main-belt asteroids observed to date in the mid-infrared. The derived diameters range from 17.3 km for 832 Karin to 1.5 km for 75176, with typical uncertainties of 10%. The mean albedo is p=0.215±0.015, compared to 0.20±0.07 for 832 Karin itself (for H=11.2±0.3), consistent with the view that the Karin asteroids are closely related physically as well as dynamically. The albedo distribution ( 0.12⩽p⩽0.32) is consistent with the range associated with S-type asteroids but the variation from one object to another appears to be significant. Contrary to the case for near-Earth asteroids, our data show no evidence of an albedo dependence on size. However, the mean albedo is lower than expected for young, fresh "S-type" surfaces, suggesting that space weathering can darken main-belt asteroid surfaces on very short timescales. Our data are also suggestive of a connection between surface roughness and albedo, which may reflect rejuvenation of weathered surfaces by impact gardening. While the available data allow only estimates of lower limits for thermal inertia, we find no evidence for the relatively high values of thermal inertia reported for some similarly sized near-Earth asteroids. Our results constitute the first observational confirmation of the legitimacy of assumptions made in recent modeling of the formation of the Karin cluster via a single catastrophic collision 5.8±0.2 Myr ago.

  3. Temperature dependence of the lattice parameter and Debye-Waller factor of a high-chromium pressure-vessel steel

    NASA Astrophysics Data System (ADS)

    Sumin, V. V.; Simkin, V. G.; Sheverev, S. G.; Leont'eva-Smirnova, M. V.; Chernov, V. M.

    2009-12-01

    The method of thermal neutron diffraction has been used to study samples of the EK-181 steel at temperatures of 15 to 973 K in an IBR-2 reactor (Joint Institute for Nuclear Research (JINR)). Temperature dependences of the lattice parameter, internal textural stresses (of the third kind), and the Debye-Waller factor of this steel have been calculated from diffraction spectra by the Rietveld method. It has been found that at low temperatures the temperature dependence of the lattice parameter in the EK-181 steel (RUSFER EK-181) differs from the corresponding dependence in pure iron and binary iron-chromium alloys containing 12 and 16% Cr. Also, a broadening of the ( 200) reflection has been observed in the diffraction spectra of the EK-181 steel and the Fe-12Cr alloy, while it is not detected in the spectra of Fe-16Cr and pure iron.

  4. Polarimetric evidence of close similarity between members of the Karin and Koronis dynamical families

    NASA Astrophysics Data System (ADS)

    Cellino, A.; Delbò, M.; Bendjoya, Ph.; Tedesco, E. F.

    2010-10-01

    We present the results of a campaign of polarimetric observations of small asteroids belonging to the Karin and Koronis families, carried out at the ESO Cerro Paranal Observatory using the VLT-Kueyen 8-m telescope. The Karin family is known to be very young, having likely been produced by the disruption of an original member of the Koronis family less than 6 Myr ago. The purpose of our study was to derive polarimetric properties for a reasonable sample of objects belonging to the two families, in order to look for possible systematic differences between them, to be interpreted in terms of differences in surface properties, in particular albedo. In turn, systematic albedo differences might be caused by different times of exposure to space weathering processes experienced by the two groups of objects. The results of our analysis indicate that no appreciable difference exists between the polarimetric properties of Karin and Koronis members. We thus find that space-weathering mechanisms may be very efficient in affecting surface properties of S-class asteroids on very short timescales. This result complements some independent evidence found by recent spectroscopic studies of very young families.

  5. Testing the Deployment Repeatability of a Precision Deployable Boom Prototype for the Proposed SWOT Karin Instrument

    NASA Technical Reports Server (NTRS)

    Agnes, Gregory S.; Waldman, Jeff; Hughes, Richard; Peterson, Lee D.

    2015-01-01

    NASA's proposed Surface Water Ocean Topography (SWOT) mission, scheduled to launch in 2020, would provide critical information about Earth's oceans, ocean circulation, fresh water storage, and river discharge. The mission concept calls for a dual-antenna Ka-band radar interferometer instrument, known as KaRIn, that would map the height of water globally along two 50 km wide swaths. The KaRIn antennas, which would be separated by 10 meters on either side of the spacecraft, would need to be precisely deployable in order to meet demanding pointing requirements. Consequently, an effort was undertaken to design build and prototype a precision deployable Mast for the KaRIn instrument. Each mast was 4.5-m long with a required dilitation stability of 2.5 microns over 3 minutes. It required a minimum first mode of 7 Hz. Deployment repeatability was less than +/- 7 arcsec in all three rotation directions. Overall mass could not exceed 41.5 Kg including any actuators and thermal blanketing. This set of requirements meant the boom had to be three times lighter and two orders of magnitude more precise than the existing state of the art for deployable booms.

  6. Atomic disorder of Li0.5Ni0.5O thin films caused by Li doping: estimation from X-ray Debye–Waller factors

    PubMed Central

    Yang, Anli; Sakata, Osami; Yamauchi, Ryosuke; Kumara, L. S. R.; Song, Chulho; Katsuya, Yoshio; Matsuda, Akifumi; Yoshimoto, Mamoru

    2015-01-01

    Cubic type room-temperature (RT) epitaxial Li0.5Ni0.5O and NiO thin films with [111] orientation grown on ultra-smooth sapphire (0001) substrates were examined using synchrotron-based thin-film X-ray diffraction. The 11 and 22 rocking curves including six respective equivalent reflections of the Li0.5Ni0.5O and NiO thin films were recorded. The RT B 1 factor, which appears in the Debye–Waller factor, of a cubic Li0.5Ni0.5O thin film was estimated to be 1.8 (4) Å2 from its 11 and 22 reflections, even though the Debye model was originally derived on the basis of one cubic element. The corresponding Debye temperature is 281 (39) K. Furthermore, the B 2 factor in the pseudo-Debye–Waller factor is proposed. This parameter, which is evaluated using one reflection, was also determined for the Li0.5Ni0.5O thin film by treating Li0.5Ni0.5O and NiO as ideal NaCl crystal structures. A structural parameter for the atomic disorder is introduced and evaluated. This parameter includes the combined effects of thermal vibration, interstitial atoms and defects caused by Li doping using the two Debye–Waller factors. PMID:26664345

  7. Effect of Particle Size and Lattice Strain on the Debye-Waller Factors of Silicon Carbide Nanoparticles.

    PubMed

    Purushotham, E

    2016-03-01

    Nano Silicon Carbide (SiC) particles have been produced by ball milling process. The sample was taken 0, 10, 20, 30, 40 and 50 hours of milling. The resulting nanoparticle powders were characterized by X-ray diffraction measurements. The high-energy ball milling of SiC after 50 hours resulted in particle size of about 24 nm. The Debye temperature, mean-square amplitudes of vibration, Debye-Waller factor, particle size, and lattice strain and vacancy formation of energies of SiC nanoparticles prepared by ball mill have been obtained from X-ray integrated intensities. The integrated intensities have been measured with a Philips CWU 3710 X-ray powder diffractometer fitted with a scintillation counter using filtered CuKα radiation at room temperature and have been corrected for thermal diffuse scattering. The X-ray Debye temperatures obtained in the present investigation has been used to estimate the vacancy formation energies for SiC nanoparticles. PMID:27455685

  8. Modeling asteroid surfaces from observations and irradiation experiments: The case of 832 Karin

    NASA Astrophysics Data System (ADS)

    Brunetto, Rosario; Vernazza, Pierre; Marchi, Simone; Birlan, Mirel; Fulchignoni, Marcello; Orofino, Vincenzo; Strazzulla, Giovanni

    2006-10-01

    We define a new approach to model asteroidal space weathering. We started from recent results of ion irradiation experiments (60-400 keV) of meteorites and silicates to give an accurate description of space weathering, and we included its effects in the Shkuratov model. We found that the reddening and darkening process (in the range 0.3-2.5 μm) does not significantly affect the position or relative intensities of the mafic silicate absorption features and it mainly affects the continuum of reflectance spectra. This continuum is parameterized by a C coefficient, which is strongly related with the number of displacements per unit area (damage parameter); we consequently obtained an exposure time curve, and corresponding astrophysical timescales. We applied this new description of space weathering to model observed spectra of Asteroid 832 Karin, in the 0.4-2.4 μm spectral region. The obtained exposure time is slightly lower than the age of the impact and collisional breakup which originated the Karin asteroidal family, i.e., about 5.75×10 years.

  9. A spectral model for irradiated silicates: application to asteroid 832 Karin

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Vernazza, P.; Marchi, S.; Birlan, M.; Fulchignoni, M.; Orofino, V.; Strazzulla, G.

    We define a new approach to space weathering of airless bodies, and include its effect in the Shkuratov model. We start from recent results of ion irradiation experiments (60-400 keV) of meteorites and silicates; we find that the reddening and darkening process (in the range 0.3-2.5 microns) mainly affects the continuum of reflectance spectra (parameterized by a Cs coefficient), but it does not significantly affect the position or relative intensities of the mafic silicate absorption features. The Cs coefficient is strongly related with the number of displacements per unit area (damage parameter); we consequently obtain an exposure time curve, and corresponding astrophysical timescales. We apply this new description of space weathering to model observed spectra of asteroid 832 Karin, in the 0.4-2.4 microns spectral region. The obtained exposure time is slightly lower than the age of the impact and collisional breakup which originated the Karin asteroidal family, i.e. about 5.75 My.

  10. Self-Consistent Interpretation of the 2D Structure of the Liquid Au82Si18 Surface: Bending Rigidity and the Debye-Waller Effect

    NASA Astrophysics Data System (ADS)

    Mechler, S.; Pershan, P. S.; Yahel, E.; Stoltz, S. E.; Shpyrko, O. G.; Lin, B.; Meron, M.; Sellner, S.

    2010-10-01

    The structural and mechanical properties of 2D crystalline surface phases that form at the surface of liquid eutectic Au82Si18 are studied using synchrotron x-ray scattering over a large temperature range. In the vicinity of the eutectic temperature the surface consists of a 2D atomic bilayer crystalline phase that transforms into a 2D monolayer crystalline phase during heating. The latter phase eventually melts into a liquidlike surface on further heating. We demonstrate that the short wavelength capillary wave fluctuations are suppressed due to the bending rigidity of 2D crystalline phases. The corresponding reduction in the Debye-Waller factor allows for measured reflectivity to be explained in terms of an electron density profile that is consistent with the 2D surface crystals.

  11. Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn)

    NASA Technical Reports Server (NTRS)

    Esteban-Fernandez, Daniel; Rodriquez, Ernesto; Peral, Eva; Clark, Duane I.; Wu, Xiaoqing

    2011-01-01

    An interferometric synthetic aperture radar (SAR) onboard processor concept and algorithm has been developed for the Ka-band radar interferometer (KaRIn) instrument on the Surface and Ocean Topography (SWOT) mission. This is a mission- critical subsystem that will perform interferometric SAR processing and multi-look averaging over the oceans to decrease the data rate by three orders of magnitude, and therefore enable the downlink of the radar data to the ground. The onboard processor performs demodulation, range compression, coregistration, and re-sampling, and forms nine azimuth squinted beams. For each of them, an interferogram is generated, including common-band spectral filtering to improve correlation, followed by averaging to the final 1 1-km ground resolution pixel. The onboard processor has been prototyped on a custom FPGA-based cPCI board, which will be part of the radar s digital subsystem. The level of complexity of this technology, dictated by the implementation of interferometric SAR processing at high resolution, the extremely tight level of accuracy required, and its implementation on FPGAs are unprecedented at the time of this reporting for an onboard processor for flight applications.

  12. KaRIn on SWOT: modeling and simulation of near-nadir Ka-band interferometric SAR images

    NASA Astrophysics Data System (ADS)

    Fjørtoft, Roger; Koudogbo, Fifamè; Duro, Javier; Ruiz, Christian; Gaudin, Jean-Marc; Mallet, Alain; Pourthie, Nadine; Lion, Christine; Ordoqui, Patrick; Arnaud, Alain

    2010-10-01

    The principal instrument of the wide-swath altimetry mission SWOT is KaRIn, a Ka-band interferometric SAR system operating on near-nadir swaths on both sides of the satellite track. Due to the short wavelength and particular observation geometry, there are very limited reports on the backscattering from natural surfaces. Simulators that cover both radiometric and geometric aspects are therefore developed in the framework of the CNES phase 0 and A studies of SWOT. This article presents the modeling and simulation approaches that have been adopted, and shows some preliminary simulation results.

  13. Wrongful death claims. Harriton v Stephens. [2002] NSWSC 461. Edwards v Blomeley. [2002] NSWSC 460. Waller v James [2002] NSWSC 462.

    PubMed

    Devereux, John

    2002-11-01

    Studdert J in all three cases went to great length to summarise the global judicial position of "wrongful life" claims. He did not, however, examine in great length how or whether "wrongful life" claims or "wrongful birth" claims are reconcilable with tort and common law principles. Although the cases identify the difficulty in assessing and quantifying damages, they do not directly address the strict legal principles which apply in the assessment of damages. The main conclusion of the three judgments was that no duty of care is owed to the plaintiff in these circumstances and, even if a duty could be established, the impossibility of quantifying damages and public policy considerations warrant the rejection of such a claim: "thus conscience does make cowards of us all." The significance of the decisions cannot be understand. The decisions deny recognition of "wrongful life" claims in circumstances where a disabled person has incurred injuries en ventre sa mere (in the mother's womb) as a result of infections contracted by a plaintiff's mother or genetic material passed on by a plaintiff's parents. Some countries have now legislated for the abolition of "wrongful life and birth" suits. In January 2002 the French legislature passed a Bill overturning the "wrongful life" decision of the Cour de Cassation in Perruche (17 November 2000). As the issue now falls for ultimate determination by the French Senate, the French pro-life movement continues to lobby for the prohibition of "wrongful birth" suits as well. Furthermore, eight States in the United States have prohibited either one or both actions and the State of Michigan prohibited both actions in 2001. It is likely that all three cases will be appealed. The appeal in Harriton will re-examine the viability of a "wrongful life" claim in Australia whereas the cases of Edwards and Waller still need to determine the "wrongful birth" claims brought by the plaintiffs' parents. It is likely that the latter two cases will

  14. An alternative explanation of the change in T-dependence of the effective Debye-Waller factor at Tc or TB

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.; Habasaki, J.

    2014-09-01

    The cusp-like temperature dependence of the Debye-Waller factor or non-ergodicity parameter fQ(T) at some temperature Tc above Tg found by experiments in several fragile glassformers has been considered as critical evidence for validity of the ideal Mode Coupling Theory (MCT). A comprehensive review of experimental data of fQ(T) and beyond brings out various problems of the MCT predictions. For example, the molten salt, 0.4Ca(NO3)2-0.6KNO3 (CKN), was the first glassformer measured by neutron scattering to verify the cusp-like behavior of fQ(T) at Tc predicted by ideal MCT. While the fits of the other scaling laws of MCT to viscosity, light scattering, and dielectric relaxation data all give Tc in the range from 368 to 375 K, there is no evidence of cusp-like behavior of fQ(T) at Tc from more accurate neutron scattering data obtained later on by Mezei and Russina [J. Phys.: Condens. Matter 11, A341 (1999)] at temperatures below 400 K. In several molecular glass-formers, experiments have found at temperatures below Tc that [1-fQ(T)] is manifested as nearly constant loss (NCL) in the frequency dependent susceptibility. The NCL persists down to below Tg and is not predicted by the ideal MCT. No clear evidence of the change of T-dependence of fQ(T) at any Tc was found in intermediate and strong glassformers, although ideal MCT does not distinguish fragile and strong glassformers in predicting the critical behavior of fQ(T) a priori. Experiments found fQ(T) changes T-dependence not only at Tc but also at the glass transition temperature Tg. The changes of T-dependence of fQ(T) at Tc and Tg are accompanied by corresponding changes of dynamic variables and thermodynamic quantities at TB ≈ Tc and at Tg. The dynamic variables include the relaxation time τα(T), the non-exponentiality parameter n(T), and the generalized fragility m(T) of the structural α-relaxation. The thermodynamic quantities are the free volume deduced from positron annihilation spectroscopy, and the

  15. An alternative explanation of the change in T-dependence of the effective Debye-Waller factor at T{sub c} or T{sub B}

    SciTech Connect

    Ngai, K. L.; Habasaki, J.

    2014-09-21

    The cusp-like temperature dependence of the Debye-Waller factor or non-ergodicity parameter f{sub Q}(T) at some temperature T{sub c} above T{sub g} found by experiments in several fragile glassformers has been considered as critical evidence for validity of the ideal Mode Coupling Theory (MCT). A comprehensive review of experimental data of f{sub Q}(T) and beyond brings out various problems of the MCT predictions. For example, the molten salt, 0.4Ca(NO{sub 3}){sub 2}-0.6KNO{sub 3} (CKN), was the first glassformer measured by neutron scattering to verify the cusp-like behavior of f{sub Q}(T) at T{sub c} predicted by ideal MCT. While the fits of the other scaling laws of MCT to viscosity, light scattering, and dielectric relaxation data all give T{sub c} in the range from 368 to 375 K, there is no evidence of cusp-like behavior of f{sub Q}(T) at T{sub c} from more accurate neutron scattering data obtained later on by Mezei and Russina [J. Phys.: Condens. Matter 11, A341 (1999)] at temperatures below 400 K. In several molecular glass-formers, experiments have found at temperatures below T{sub c} that [1−f{sub Q}(T)] is manifested as nearly constant loss (NCL) in the frequency dependent susceptibility. The NCL persists down to below T{sub g} and is not predicted by the ideal MCT. No clear evidence of the change of T-dependence of f{sub Q}(T) at any T{sub c} was found in intermediate and strong glassformers, although ideal MCT does not distinguish fragile and strong glassformers in predicting the critical behavior of f{sub Q}(T) a priori. Experiments found f{sub Q}(T) changes T-dependence not only at T{sub c} but also at the glass transition temperature T{sub g}. The changes of T-dependence of f{sub Q}(T) at T{sub c} and T{sub g} are accompanied by corresponding changes of dynamic variables and thermodynamic quantities at T{sub B} ≈ T{sub c} and at T{sub g}. The dynamic variables include the relaxation time τ{sub α}(T), the non-exponentiality parameter n(T), and

  16. KaRIN: an Instrument for Measuring High-Resolution Sea-Surface Topography and Fresh Water Extent, Stage, and Slope

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Moller, D.; Enjolras, V.

    2006-12-01

    Traditional nadir profiling altimeters, such as Topex, Jason, or IceSat, are incaple of fully sampling the space- time signatures of both ocean mesoscale and submesoscale phenomena and changes in river discharge. To overcome this limitation, we present an instrument concept, the Ka-band Radar Interferometer (KaRIN), which is able to provide the appropriate space-time sampling to sample these phenomena with a height and slope accuracy suitable to resolve topographic signatures for both ocean and land hydrology applications. Although ocean and hydrlogic applications are quite different, the required sampling characteristics are similar. Both applications require global coverage up to high latitudes (78deg). Measurement of ocean mesoscale and submesoscale phenomena requires a temporal revisit time on the order of 10 days and a height accuracy of about 2cm over a spatial scale of 2km. The sampling of river discharge requires an approximately weekly revisit time, an ability to image water bodies (to determine extent) with a spatial resolution of 100m, a height accuracy better than 10cm and a slope accuracy of 1cm/1km, after averaging over a river area equivalent to 1km x 1km. The similarity in measurement requirements allows for the possibility of meeting both ocean and hydrology requirements with a single instrument. The KaRIN instrument builds on the interferometric SAR concept demonstrated by the NASA Shuttle Radar Topography Mission (SRTM), and the Wide-Swath Ocean Altimeter concept, which was studied by NASA as a potential complement to the Ocean Surface Topography Mission (OSTM). Two major modifications are made to these systems to achieve the desired performance: the spatial sampling requirement implies that full synthetic aperture must be used. Second, achieving the desired height and slope accuracy with a realizable spaceborne instrument requires using a Ka-band (0.8 cm wavelength) radar at near nadir incidence. To validate the science performance of the

  17. The social nature of disability, disease and genetics: a response to Gillam, Persson, Holtug, Draper and Chadwick.

    PubMed Central

    Newell, C

    1999-01-01

    The dominance of the biomedically informed view of disability, genetics, and diagnosis is explored. An understanding of the social nature of disability and genetics, especially in terms of oppression, adds a richer dimension to an understanding of ethical issues pertaining to genetics. This is much wider than the limited question of whether or not such technology discriminates. Instead, it is proposed that such technology will perpetuate the oppression and control of people with disability, especially if the knowledge of people with disability is not utilised in bioethical debates. PMID:10226924

  18. Debye-Waller factor in solid He-4 at sub-Kelvin temperatures

    NASA Astrophysics Data System (ADS)

    Blackburn, Elizabeth; Goodkind, John M.; Sinha, Sunil K.; Hudis, Jacob; Broholm, Collin; van Duijn, Joost; Down, Richard; Kirichek, Oleg; Frost, Chris D.

    2007-03-01

    The recent observation by Kim and Chan [Science 305 (2204) 1941] of a transition at low temperatures (˜ 200 mK) in the hcp-phase of solid helium has re-opened interest in the old question of supersolidity. The nature of the low-temperature phase remains in question, and to investigate this in more detail, we have measured the density distribution of He-4 nuclei in crystals of He-4 with a molar volume of 21.3 cm^3 down to 140 mK. We find no evidence for any changes in the vicinity of the transition. Treating the material as a traditional crystal, we have extracted the mean square displacement for the nuclei and find anisotropy between the in- and out-of-plane motions. Our values are in agreement with previous work at higher temperatures.

  19. I.H. HALL, S.D. WYRICK, C.L. WALLER

    EPA Science Inventory

    Substituted oxoisoindolines are effective cytotoxic agents, causing cell death in a number of tissue culture lines, e.g. L1210, Tmolt-3, and HeLa-S3. n general these agents were not active against the solid cell growth, i.e. KB, skin, HCT-8 ileum, colon, bronchogenic lung, osteos...

  20. Response to commentaries by Karin Rolanda Jongsma and Suzanne van de Vathorst, and Oliver Hallich.

    PubMed

    Buller, Thomas

    2015-08-01

    The authors of the two commentaries raise some interesting and important objections to my paper, 'Advance Consent, Critical Interests, and Dementia Research'. In my response I try to show that the objections raised can be understood as general objections against advance directives, rather than against research directives in particular. Since my main argument in the paper is that if we accept advance directives for treatment then we should accept them for research, arguments showing that we should not accept advance directives at all are consistent with my point of view. PMID:25887513

  1. 75 FR 76482 - Federal Housing Administration (FHA): FHA Maximum Loan Limits for 2011

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    .../ . FOR FURTHER INFORMATION CONTACT: Karin B. Hill, Director, Office of Single Family Program Development.../. Dated: November 29, 2010. Karin Hill, Director, Office of Single Family Program Development....

  2. KARIN: The Ka-Band Radar Interferometer for the Proposed Surface Water and Ocean Topography (SWOT) Mission

    NASA Technical Reports Server (NTRS)

    Esteban-Fernandez, Daniel; Peral, Eva; McWatters, Dalia; Pollard, Brian; Rodriguez, Ernesto; Hughes, Richard

    2013-01-01

    Over the last two decades, several nadir profiling radar altimeters have provided our first global look at the ocean basin-scale circulation and the ocean mesoscale at wavelengths longer than 100 km. Due to sampling limitations, nadir altimetry is unable to resolve the small wavelength ocean mesoscale and sub-mesoscale that are responsible for the vertical mixing of ocean heat and gases and the dissipation of kinetic energy from large to small scales. The proposed Surface Water and Ocean Topography (SWOT) mission would be a partnership between NASA, CNES (Centre National d'Etudes Spaciales) and the Canadian Space Agency, and would have as one of its main goals the measurement of ocean topography with kilometer-scale spatial resolution and centimeter scale accuracy. In this paper, we provide an overview of all ocean error sources that would contribute to the SWOT mission.

  3. 75 FR 40819 - Reliability Standards Development and NERC and Regional Entity Enforcement; Notice Soliciting...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... Technical Conference, 75 FR 36,385 (June 18, 2010). Anyone with questions pertaining to the technical conference or this notice should contact either Karin Larson at 202-502-8236, Karin.Larson@ferc.gov...

  4. 75 FR 3240 - Center for Scientific Review; Notice of Closed Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-20

    ...: Karin F. Helmers, PhD, Scientific Review Officer, Center for Scientific Review, National Institutes of... Institutes of Health, 6701 Rockledge Drive, Bethesda, MD 20892, (Virtual Meeting.) Contact Person: Karin...

  5. Antipsychotics Don't Ease Delirium in Hospitalized Patients

    MedlinePlus

    ... a patient with delirium," said lead researcher Dr. Karin Neufeld, clinical director of psychiatry at Johns Hopkins ... obvious, but they are important," he added. SOURCES: Karin Neufeld, M.D., M.P.H., clinical director, ...

  6. A Catalyst for Charting a Path to Research Validity in the Field of Gifted Education

    ERIC Educational Resources Information Center

    Sisk, Dorothy A.

    2012-01-01

    Roland S. Persson's (2012a) article addresses a concern that many educators have stressed in their theoretical models, namely the importance of the interaction between the individual and the environment, and the impact of culture on not only values and beliefs, but on behaviour. As Persson (2012a) points out these models all have merit, but he…

  7. The Debate on Dominant Culture and Cultural Imperialism

    ERIC Educational Resources Information Center

    Anchan, John P.

    2012-01-01

    In this commentary, the author reviews in depth Roland S. Persson's (2012a) target article. According to him Persson (2012a) presents a convincing argument as he wove through examples and explanations. The idea of superculture connects well with the established neocolonial literature and the North-South/Centre-Periphery debate. From general to…

  8. The Surface Water and Ocean Topography Mission (SWOT): the Ka-band Radar Interferometer (KaRIn) for water level measurements at all scales

    NASA Astrophysics Data System (ADS)

    Rodriguez, Ernesto; Esteban-Fernandez, Daniel

    2010-10-01

    The Surface Water and Ocean Topography (SWOT) mission will study ocean mesoscale and submesoscale phenomena and provide an inventory of storage change and discharge for fresh water bodies and rivers. In this paper, we examine the combination of measurements that will be used by SWOT to achieve a globally consistent data set. We introduce a new channel in the SWOT measurement that combines data transmitted by the interferometer antennas and received by the radiometer antenna allows the closing of the SWOT nadir coverage gap. This new mode also allows for improved calibration between the nadir altimeter and the interferometer, resulting in consistent range measurements. Consistency in the phase measurements is achieved using a mixture of cross-over calibration combined with optimal estimation of system error drift.

  9. Bonding study of TiC and TiN. I. High-precision x-ray-diffraction determination of the valence-electron density distribution, Debye-Waller temperature factors, and atomic static displacements in TiC0.94 and TiN0.99

    NASA Astrophysics Data System (ADS)

    Dunand, A.; Flack, H. D.; Yvon, K.

    1985-02-01

    Single-crystal, high-precision, high-resolution x-ray-diffraction measurements of the substoichiometric refractory compounds TiC and TiN have been performed with AgKα radiation. Severe anisotropic general extinction affects the intense low-order reflections. Inhomogeneity in the mosaic spread and domain size produces small but significant differences between reflection and antireflection for the same plane of diffraction. These effects have been modeled and refined together with a scale factor, isotropic thermal parameters, a population parameter of the nonmetal site, the amplitude of metal-atom static displacements around nonmetal vacancies, and an atomic model which includes occupancy factors of the separate orbital contributions of the valence electrons combined with κ expansion-contraction parameters. At convergence, the ``agreement indices'' (or ``reliability factors'') were R=0.0025 for TiC0.94 and R=0.0023 for TiN0.99. The refined population parameters indicate a chemical composition of TiC0.939(9) and TiN0.99(2). The mean-square amplitudes of thermal vibrations, Ti=0.002 38(2) AṦ, C=0.003 35(8) AṦ, Ti=0.002 94(1) AṦ, and N=0.003 08(12) AṦ are consistent with the respective atomic masses. 36% of the metal atoms in TiC0.94 are involved in a relaxation around the nonmetal vacancies, being displaced from their sublattice sites by 0.097(2) Å along [100]. No evidence for static displacements was found in TiN0.99. The valence-electron density distribution can be described satisfactorily in terms of deformed atoms. No buildup of charge density occurs between atomic sites. Our analysis, similar to a Mulliken partitioning, shows first that ionicity is important, with a charge transfer from the metal to the nonmetal of [2.1(4)]e in the carbide and [1.9(4)]e in the nitride, and secondly that the charge asphericity around the metal atoms is larger in the former than in the latter, while no departure from spherical symmetry is observed around the nonmetal atoms. The titanium 3d electrons can be split into a spherical shell that contains [1.27(6)]e plus an excess of [0.24(5)]e shared by two orbitals of eg symmetry in the carbide and conversely into a spherical shell that contains [0.88(11)]e plus an excess of [0.12(9)]e shared by three orbitals of t2g symmetry in the nitride. This suggests that the metal-to-metal bonding is similar in TiC and in TiN while the metal-to-nonmetal bonding is greater in TiC than in TiN.

  10. Photometric Observation of Young Asteroid Family in 2006-2010 at Maidanak Observatory, Uzbekistan

    NASA Astrophysics Data System (ADS)

    Yoshida, F.; Nozawa, Y.; Ito, T.; Takahashi, S.; Okita, K.; Ibrahimov, M.; Ehgamberdiev, S.; Marshalkina, A.; Karimov, R.; Burhonov, O.; Tillayev, Y.; Hafizov, B.; Yanagisawa, T.; Kurosaki, H.; Yoshikawa, M.; Urakawa, S.; Ohtani, H.

    2012-05-01

    We observed 43 young family asteroids (Karin, Iannini, Veritas) and 7 old family asteroids (Koronis, Themis) at Maidanak Observatory, then determined their rotation period, lightcurve amplitude, B-V, V-R, V-I colors.

  11. Reflectance Spectra of Members of Very Young Asteroid Families

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Enke, B.; Merline, W. J.; Nesvorný, D.; Tamblyn, P.; Young, E. F.

    2009-03-01

    We present SpeX infrared spectra for members of the dynamically young Datura, Iannini, Karin, and Veritas asteroid families (plus Koronis and Themis family controls). S-types are space-weathered on timescales of a few million years.

  12. 75 FR 35021 - Reliability Standards Development and NERC and Regional Entity Enforcement; Notice of Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... conference may be directed to: Karin L. Larson, Office of the General Counsel--Energy Markets, Federal Energy Regulatory Commission, 888 First Street, NE., Washington, DC 20426, (202) 502-8236,...

  13. Research Needs in Business Education.

    ERIC Educational Resources Information Center

    D'Onofrio, Marianne J., Ed.; And Others

    1990-01-01

    Set of five articles includes "Introduction" (D'Onofrio); "Teaching Higher-Order Thinking Skills" (Maxam); "Research Questions in Teaching Software" (Franz, Waller); "Research in International Business Education" (Blockhus); and "The Knowledge Worker and Computer Technology" (Graf). (JOW)

  14. IFLA General Conference, 1990. Division of Collections and Services: Section of Acquisition and Exchange; Section of Interlending and Document Delivery, Section of Serial Publications. Booklet 5.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    The 25 papers in this collection were presented at the meetings of three sections of the Division of Collections and Services and a workshop: (1) "Survey of International Exchange of Non-Official Publications: Progress Report" (Ulla Hojsgaard); (2) "Buying Media for Everyone: Public Library Acquisition in Scandinavia" (Tove Persson); (3) "The…

  15. On Universals, Cultural Variations and Individual Uniqueness: Throwing down the Gauntlet in Giftedness Research

    ERIC Educational Resources Information Center

    Garces-Bacsal, Rhoda Myra

    2012-01-01

    Roland S. Persson's (2012a) piece is extremely comprehensive, timely and very relevant especially in light of a growing appreciation of cultural diversity and the emergence of a global community--which is an inevitable offshoot of globalisation that goes beyond world economy and international markets. It covers multiple themes; ranging from…

  16. Critique of Cultural Variation and Dominance in a Globalised Knowledge-Economy: Towards a Culture-Sensitive Research Paradigm in the Science of Giftedness

    ERIC Educational Resources Information Center

    Harris, Carole Ruth

    2012-01-01

    Persson's (2012a) article is concerned with giftedness research in the light of cultural bias with a view to cultural dominance that derives from ethnocentricity. He questions the validity of current research that appears to ignore or sidestep cultural difference and proposes that an agenda for amelioration of such bias lies in greater awareness…

  17. In the Shadows of Dominant Cultures: The Elusive Definition of Giftedness

    ERIC Educational Resources Information Center

    Polyzoi, Eleoussa; Haydey, Donna Copsey

    2012-01-01

    In this commentary, the authors contend that Persson's (2012a) paper, Cultural Variation and Dominance in a Globalised Knowledge-Economy: Towards a Culture-Sensitive Research Paradigm in the Science of Giftedness, lacks conciseness in defining the connections between the significance of cultural dominance and the definition of giftedness. However,…

  18. Some Thoughts on "Cultural Variation and Dominance in a Globalised Knowledge-Economy"

    ERIC Educational Resources Information Center

    Yang, Yang; Gentry, Marcia

    2012-01-01

    To view giftedness research in a global context is an important and desirable attempt. Roland S. Persson (2012a), in the target article entitled Cultural Variation and Dominance in a Globalised Knowledge-Economy: Towards a Cultural-Sensitive Research Paradigm in the Science of Giftedness, delivers thought-provoking views in the cultural influences…

  19. Basic Framework to Understand Identity Development in a Multicultural Context

    ERIC Educational Resources Information Center

    Shaughnessy, Michael F.; Valdez, Gilbert

    2012-01-01

    In the lead article, Persson (2012a) focuses on salient issues that have not as yet been addressed by others, and which are relevant, and germane. With the advent of the Internet and web and e-mail, conversation and discussion among scholars have increased tremendously. At the current time, researchers are able to share their data, their thoughts…

  20. The Recognition of Cultural Bias in Researching Those Labelled Gifted: An Overdue Perspective

    ERIC Educational Resources Information Center

    Mazzoli Smith, L.; Campbell, R. J.

    2012-01-01

    This commentary addresses the analysis in Persson's (2012a) article. According to the authors, the agenda for change amongst scholars has four productive proposals. These are: (1) that scholars should broaden their disciplinary outlook beyond psychology and education; (2) that they should eschew policy borrowing; (3) that they should clarify, for…

  1. The Scenic Route Is Not Always the Most Informative

    ERIC Educational Resources Information Center

    Freeman, Joan

    2012-01-01

    Roland S. Persson's (2012a) argument is that there is a dominant research culture in the field of gifts and talents, which must of necessity distort research and practice in cultures which are different. He ties this to the dominance of the global economy and points to the need for more cross-cultural studies. In this commentary, the author points…

  2. Probing Asteroid Families for Evidence of Ultraviolet Space Weathering Effects

    NASA Astrophysics Data System (ADS)

    Vilas, Faith

    2005-07-01

    We propose six HST orbits to obtain UV reflectance spectra covering 200-460 nm of two Vesta asteroid family members, asteroid 832 Karin, and two Karin family members. These observations extend work done under a Cycle 13 AR grant, where we analyzed all of the existing IUE and HST S-class asteroids in the MAST database to investigate the effects of space weathering at UV wavelengths. Our hypothesis is that the manifestation of space weathering at UV wavelengths is a spectral bluing, in contrast with a spectral reddening at visible-NIR wavelengths, and that UV wavelengths can be more sensitive to relatively small amounts of weathering than longer wavelengths. The proposed observations will address two objectives: {1} Measure the UV-visible spectra of 832 Karin and two members of the young Karin family {absolute age of 5.8 My}, in order to determine whether intermediate space weathering is observable in objects likely pristine when they originated from the interior of Karin's pa rent body. {2} Measure the UV-visible spectra of two members of the Vesta family to compare with our analysis of IUE Vesta spectra. These observations will probe Vesta's interior, and test our hypothesis by contrasting the apparent amount of alteration on the surfaces of Vestoids with excavated material on Vesta.

  3. The Misfortunes of Moral Enhancement.

    PubMed

    Azevedo, Marco Antonio

    2016-10-01

    In Unfit for the Future, Ingmar Persson and Julian Savulescu present a sophisticated argument in defense of the imperative of moral enhancement. They claim that without moral enhancement, the future of humanity is seriously compromised. The possibility of ultimate harm, caused by a dreadful terrorist attack or by a final unpreventable escalation of the present environmental crisis aggravated by the availability of cognitive enhancement, makes moral enhancement a top priority. It may be considered optimistic to think that our present moral capabilities can be successfully improved by means of moral education, moral persuasion, and fear of punishment. So, without moral enhancement, drastic restrictions on human freedom would become the only alternative to prevent those dramatic potential outcomes. In this article, I will try to show that we still have reason to be less pessimistic and that Persson & Savulescu's arguments are fortunately unconvincing. PMID:27473409

  4. 78 FR 45541 - Center for Scientific Review ;Notice of Closed Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ... Committee: Center for Scientific Review Special Emphasis Panel; OppNet RFA: Culture, Health and Wellbeing... HUMAN SERVICES National Institutes of Health Center for Scientific Review ;Notice of Closed Meeting... Call). Contact Person: Karin F Helmers, Ph.D., Scientific Review Officer, Center for Scientific...

  5. Getting It Done: Leading Academic Success in Unexpected Schools

    ERIC Educational Resources Information Center

    Chenoweth, Karin; Theokas, Christina

    2011-01-01

    "Getting It Done" describes in clear and helpful detail what leaders of successful high-poverty and high-minority schools have done to promote and sustain student achievement. It follows two celebrated books by Karin Chenoweth: "It's Being Done," which established that the work of educating all children is possible, and "How It's Being Done,"…

  6. Astronaut James Wetherbee briefed on use of Sky Genie

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut James D. Wetherbee, STS-63 mission commander, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  7. Psycholinguistics and Foreign Language Learning. Papers from a Conference (Stockholm, Sweden and Abo, Finland, October 25-26, 1982). Meddelanden fran Stiftelsens for Abo Akademi Forskningsinstitut Nr.86.

    ERIC Educational Resources Information Center

    Ringbom, Hakan, Ed.

    At irregular intervals, beginning in 1977, Swedish-Finnish conferences on contrastive and applied linguistics have been arranged in Stockholm and Turko/Abo. This volume presents most of the papers given at the 1982 conference. Papers include: "Free Recall of Mixed Language Lists. Error Patterns in Bilingual Memory" (Karin Aronsson, Anja Metsola,…

  8. "Oya?"--O, Ja! Reading "Jugendliteratur" in the German Classroom.

    ERIC Educational Resources Information Center

    Moffit, Gisela

    1998-01-01

    Makes a plea for reading authentic "Jugendliteratur" in the foreign-language classroom. Focuses on the reasons for inclusions of this literature, discusses some of the reasons for its omission, and offers solutions to the problems perceived. Strategies for reading whole texts are shared and applied to the reading of "Oya" by Karin Konig, Hanne…

  9. How It's Being Done: Urgent Lessons from Unexpected Schools

    ERIC Educational Resources Information Center

    Chenoweth, Karin

    2009-01-01

    "How It's Being Done" offers much-needed help to educators, providing detailed accounts of the ways in which unexpected schools--those with high-poverty and high-minority student populations--have dramatically boosted student achievement and diminished (and often eliminated) achievement gaps. "How It"s Being Done" builds on Karin Chenoweth's…

  10. Persistent Discourses in Physics Education: Gender Neutrality and the Gendering of Competence

    ERIC Educational Resources Information Center

    Gonsalves, Allison

    2014-01-01

    In her article, Karin Due presents us with a contradiction in physics: the construction of physics as a symbolically masculine discipline alongside a simultaneous discourse of the "gender-neutrality" of the discipline. Due's article makes an important contribution to the study of the gendering of physics practices, particularly in…

  11. 77 FR 39499 - Center For Scientific Review; Notice of Closed Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... HUMAN SERVICES National Institutes of Health Center For Scientific Review; Notice of Closed Meetings... Committee: Center for Scientific Review Special Emphasis Panel Revisions on the Protections for Human...: Karin F. Helmers, Ph.D., Scientific Review Officer, Center for Scientific Review, National Institutes...

  12. Astronaut Eileen Collins is briefed on use of Sky Genie

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Eileen M. Collins, STS-63 mission pilot, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  13. The Role of Shared Knowledge in Science: The Failure of the Constructivist Programme in the Sociology of Science.

    ERIC Educational Resources Information Center

    Freudenthal, Gad

    1984-01-01

    Discusses various aspects of contructivism, focusing on the work of Karin Knorr-Cetina. Indicates that an internal critique of Knorr's arguments for the relativist program in the sociology highlights the role of shared knowledge in science and that Knorr's analysis produces new insights concerning the necessity and nature of scientific consensus.…

  14. Varia. Working Papers in Linguistics No. 47.

    ERIC Educational Resources Information Center

    Dowty, David, Ed.; And Others

    1995-01-01

    Papers in phonology, psycholinguistics, and syntax include: "Discriminating between Syntactic and Semantic Processing: Evidence from Event-Related Potentials" (Kim Ainsworth-Darnell); "The Syntactic Structure of Chinese Formal Focus" (Qian Gao); "Employing a Multimodal Logic in an Approach to German Pronoun Fronting" (Karin Golde); "The…

  15. 75 FR 66038 - Planning Resource Adequacy Assessment Reliability Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ...-6652 or toll-free at 1-866-208-3676. FOR FURTHER INFORMATION CONTACT: Karin L. Larson (Legal Information), Office of the General Counsel, Federal Energy Regulatory Commission, 888 First Street, NE., Washington, DC 20426, (202) 502-8236. Scott Sells (Technical Information), Office of Electric...

  16. Astronaut C. Michael Foale is briefed on use of Sky Genie

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut C. Michael Foale, STS-63 mission specialist, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  17. Epistemic Practices and Object Relations in Professional Work

    ERIC Educational Resources Information Center

    Nerland, Monika; Jensen, Karen

    2012-01-01

    Professional practice is embedded in complex dynamics of knowledge that are present within, but reach beyond, local work. Knowledge is generated from a manifold of sources, and further developed and circulated in professional communities as practitioners are confronted with non-routine problems. Drawing on the work of Karin Knorr Cetina and her…

  18. Communication of Love and Decision-Making Power in Dating Relationships.

    ERIC Educational Resources Information Center

    Ting-Toomey, Stella

    A study explored the relationship between romantic love and decision making power in college students' dating relationships. W. Waller's theory that the person who is "least in love" gains power over the person who is relatively "more in love" was tested in terms of C. Safilios-Rothchild's typology of "Orchestration Power" (infrequent but…

  19. Brokenhearts: Dissolution of Romantic Relationships.

    ERIC Educational Resources Information Center

    Meeker, F. B.; La Fong, Carl

    Results of an investigation examining the dissolution of romantic relationships are analyzed. Men and women (N=105) who had ended romantic relationships were surveyed in structured individual interviews. Commonalities and differences in respondents' perceptions of the experience were examined. Specific tests were made of a corollary to Waller's…

  20. The Role of Personality in the Selection of a Major: With and without Vocational Self-Efficacy and Interests

    ERIC Educational Resources Information Center

    Larson, Lisa M.; Wu, Tsui Feng; Bailey, Donna C.; Gasser, Courtney E.; Bonitz, Verena S.; Borgen, Fred H.

    2010-01-01

    The purpose of this study is to examine the role of personality traits measured by the Multidimensional Personality Questionnaire (MPQ; [Tellegen, 2000] and [Tellegen and Waller, 2008]) in selecting educational majors. Personality traits were examined alone, and with the combination of Holland's hexagonal confidence domains, as measured by the…

  1. Correcting Distance Estimates by Interacting With Immersive Virtual Environments: Effects of Task and Available Sensory Information

    ERIC Educational Resources Information Center

    Waller, David; Richardson, Adam R.

    2008-01-01

    The tendency to underestimate egocentric distances in immersive virtual environments (VEs) is not well understood. However, previous research (A. R. Richardson & D. Waller, 2007) has demonstrated that a brief period of interaction with the VE prior to making distance judgments can effectively eliminate subsequent underestimation. Here the authors…

  2. Testing a Readable Writing Approach to Text Revision.

    ERIC Educational Resources Information Center

    Duffy, Thomas M.; Kabance, Paula

    1982-01-01

    The present findings imply that a readability formula is not an effective writing production criterion, even when the writer does not deliberately write to the formula. Comprehensibility of text might be better controlled through the proper use of the transformer concept (MacDonald-Ross and Waller). (Author/PN)

  3. Sex Role Attitudes and Perceived Dating-Mating Choices of Youth.

    ERIC Educational Resources Information Center

    Hansen, Sally L.; Hicks, Mary W.

    1980-01-01

    Investigates the effects of gender, race, demographic, and sex role variables on date and mate preferences of 168 college students 18 to 22 years of age. Personality characteristics were found to be most important in choosing a date or mate. The study provides no support for the rating-dating complex described by Waller. (RMH)

  4. Leading Change in the Primary Science Curriculum

    ERIC Educational Resources Information Center

    Waller, Nicky; Baker, Chris

    2014-01-01

    Nicky Waller and Chris Baker believe that change can be a good thing and explain how their training has helped others to adjust to the new science curriculum. In September 2013, teachers across England received the definitive version of the new primary curriculum "Leading Change in the Primary Science Curriculum." This course aimed to…

  5. SHORTER MENSTRUAL CYCLES ASSOCIATED WITH CHLORINATION BY-PRODUCTS IN DRINKING WATER

    EPA Science Inventory

    Shorter Menstrual Cycles Associated with Chlorination by-Products in Drinking Water.
    Gayle Windham, Kirsten Waller, Meredith Anderson, Laura Fenster, Pauline Mendola, Shanna Swan. California Department of Health Services.

    In previous studies of tap water consumption we...

  6. STRAIN COMPARISON IN PREGNANT RATS OF ENDOCRINE RESPONSE TO BROMODICHLOROMETHANE: A DRINKING WATER DISINFECTION BY-PRODUCT

    EPA Science Inventory

    Bromodichloromethane (BDCM), a trihalomethane, is a by-product of the chlorination of drinking water. In an epidemiological study, consumption of drinking water with high levels of BDCM was associated with an increased risk of spontaneous abortion in pregnant women (Waller et al....

  7. TIME TO PREGNANCY IN RELATION TO TOTAL TRIHALOMETHANE LEVELS IN TAP WATER

    EPA Science Inventory

    Time to pregnancy in relation to total trihalomethane levels in tap water
    Shanna H. Swan, Cuirong Ren, Gayle C. Windham, Laura Fenster, Kirsten Waller. (University of Missouri and California Department of Health Services).

    We have previously reported increased risks o...

  8. Culture and Leadership in Educational Administration: A Historical Study of What Was and What Might Have Been

    ERIC Educational Resources Information Center

    Bates, Richard

    2006-01-01

    This paper examines the consequences for school leadership of the abandonment of Waller's insights into the school as a social organism and the embracing of the cult of efficiency as the foundation for the analysis of school culture. Tracing the separation of conception from execution, leadership from teaching, administration from education…

  9. 78 FR 19599 - Approval and Promulgation of Implementation Plans; Texas; Reasonably Available Control Technology...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-02

    ...The EPA is finalizing its proposal to approve revisions to the Texas State Implementation Plan (SIP) for the Houston/Galveston/ Brazoria (HGB) 1997 8-Hour ozone nonattainment Area (Area). The HGB Area consists of Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery and Waller counties. Specifically, we are finalizing our proposed approval of portions of two revisions to the......

  10. Blacks in Pop Music: A Short Story.

    ERIC Educational Resources Information Center

    Rickelman, Melinda

    1991-01-01

    A short history of black pop music includes artists who have changed pop music or culture and highlights from the 1920s into the 1980s, from Fats Waller to Michael Jackson. In black pop music, there is a direct line of influence from the sharecropper to the current Top 40. (SLD)

  11. What Doth It Profit? The Study of Mountain Religion.

    ERIC Educational Resources Information Center

    Salstrom, Paul; And Others

    1990-01-01

    Five papers examine mountain religion, focusing on Jeff Todd Titon's book, "Powerhouse of God: Speech, Chant, and Song in an Appalachian Baptist Church." Discussants include Paul Salstrom; Deborah Vansau McCauley; Howard Dorgan; Altina Waller; and Charles T. Davis. Titon responds, explaining his views and study of religion. (TES)

  12. TRIHALOMETHANE LEVELS IN HOME TAP WATER AND SEMEN QUALITY

    EPA Science Inventory

    Trihalomethane Levels in Home Tap Water and Semen Quality
    Laura Fenster, 1 Kirsten Waller, 2 Gayle Windham, 1 Tanya Henneman, 2 Meredith Anderson, 2 Pauline Mendola, 3 James W. Overstreet, 4 Shanna H. Swan5

    1California Department of Health Services, Division of Environm...

  13. CHLORINATION BY-PRODUCTS IN DRINKING WATER AND MENSTRUAL CYCLE FUNCTION

    EPA Science Inventory

    Chlorination by-Products in Drinking Water and Menstrual Cycle Function

    Gayle C. Windham1, Kirsten Waller2, Meredith Anderson2, Laura Fenster1, Pauline Mendola3, Shanna Swan4

    1California Department of Health Services, Division of Environmental and Occupational Disea...

  14. Attachment Style and Dysfunctional Career Thoughts: How Attachment Style Can Affect the Career Counseling Process

    ERIC Educational Resources Information Center

    van Ecke, Yolanda

    2007-01-01

    This article examines the relationship between attachment style, measured by Experiences in Close Relationships-Revised (R C. Fraley, N. G. Waller, & K. A. Brennan, 2000), and dysfunctional career thoughts, measured by the Career Thoughts Inventory (CTI; J. P. J. Sampson, G. W. Peterson, J. G. Lenz, R. C. Reardon, & D. E. Saunders, 1994a). Two…

  15. Stretching the boundaries

    NASA Astrophysics Data System (ADS)

    2012-08-01

    Tom Waller of swimwear manufacturer Speedo's global research and development facility, Aqualab, talked to Nature Materials about the competitive sporting goods industry and the technology behind their new racing system that will be put to the test at the 2012 Olympic Games in London.

  16. IMPROVING EXPOSURE ASSESSMENT IN DISINFECTION BYPRODUCTS (DBP) EPIDEMIOLOGIC STUDIES

    EPA Science Inventory

    In 1997, an EPA expert panel was convened to evaluate epidemiologic studies of adverse reproductive or developmental outcomes that may be associated with drinking water DBPs. The panel recommended that further efforts be made in an existing cohort study, headed by Dr. Waller and ...

  17. IMPROVING EXPOSURE ASSESSMENT IN DBP EPIDEMIOLOGIC STUDIES

    EPA Science Inventory

    In 1997, an EPA expert panel was convened to evaluate epidemiologic studies of adverse reproductive or developmental outcomes that may be associated with drinking water DBPs. The panel recommended that further efforts be made in an existing cohort study, headed by Dr. Waller and ...

  18. Relationship of Purported Measures of Pathological and Nonpathological Dissociation to Self-Reported Psychological Distress and Fantasy Immersion

    ERIC Educational Resources Information Center

    Levin, Ross; Spei, Ekaterina

    2004-01-01

    In order to investigate both the psychometric structure of the Dissociative Experiences Survey (DES) and the discriminant validity of the DES-Taxon (Waller, Putnam, & Carlson, 1996) as a specific marker of pathological dissociation, 376 non-clinical community based respondents completed the DES and a battery of psychopathology and imaginative…

  19. Space weathering: from laboratory to observations .

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Orofino, V.; Strazzulla, G.

    An ongoing research program in our laboratories is focusing on the effects of laser ablation and ion irradiation on silicates, meteorites, and ices, as a simulation of space weathering on Solar System minor bodies (asteroids, Trans-Neptunian Objects, etc.). Spectroscopic results show a general reddening and darkening of the various materials in the 0.3-2.7 mu m range. Laboratory data are then compared with observations, through spectral characterization and scattering models, indicating that space weathering is a very efficient process both in the inner and outer Solar System. In particular, we demonstrated that the majority of TNOs and Centaurs can develop an organic crust mantle produced after irradiation of simple C-bearing molecules. Another relevant result is that the exposure to surface space weathering of asteroid 832 Karin, as calculated from our experiments and models, is in agreement with a dynamical time-scale, i.e. the age of the corresponding Karin family.

  20. Perspectives on Positioning, Interaction, and Learning in Small-Group Discussion: Possibilities for Extending the Analytic Lens

    ERIC Educational Resources Information Center

    Kittleson, Julie M.; Wilson, Rachel E.

    2014-01-01

    In this forum piece, we respond to Karin Due's study of social dynamics in groups of students in physics class and gender issues that play out in this context. We discuss two threads that appear in Due's paper: one pertains to patterns of talk within groups and how these patterns open up possibilities for learning, the other pertains to…

  1. ASBMB Journal Club - Office of Cancer Clinical Proteomics Research

    Cancer.gov

    On Wednesday, November 12, 2014 from 2:00 PM to 3:00 PM EST, Daniel Liebler, PhD (Vanderbilt University) and Karin Rodland, PhD (Pacific Northwestern National Laboratory) and Ruedi Aebersold, PhD (Swiss Federal Institute of Technology) will share their research insight as part of the ASBMB Journal Club.  Both Doctors Liebler and Rodland are Principal Investigators in the NCI’s Clinical Proteomic Tumor Analysis Consortium.

  2. Asperity contact theories: Do they predict linearity between contact area and load?

    NASA Astrophysics Data System (ADS)

    Carbone, G.; Bottiglione, F.

    During the last few years, the scientific community has been debating about which theory of contact between rough surfaces can be considered as the most accurate. The authors have been attracted by such a discussion and in this paper try to give their personal thought and contribution to this debate. We present a critical analysis of the principal contact theories of rough surfaces. We focus on the multiasperity contact models (which are all based on the original idea of Greenwood and Williamson (GW) [1966. Proc. R. Soc. London A 295, 300]), and also briefly discuss a relatively recent contact theory developed by Persson [2001. J. Chem. Phys. 115, 3840]. For small loads both asperity contact models and Persson's theory predict a linear relation between the area of true contact and the applied external load, but the two theories differ for the constant of proportionality. However, this is not the only difference between the two approaches. Indeed, we show that the fully calculated predictions of asperity contact models very rapidly deviates from the predicted linear relation already for very small and in many cases unrealistic vanishing applied loads and contact areas. Moreover, this deviation becomes more and more important as the PSD breadth parameter α (as defined by Nayak) increases. Therefore, the asymptotic linear relation of multiasperity contact theories turns out to be only an academic result. On the contrary, Persson's theory is not affected by α and shows a linear behavior between contact area and load up to 10-15% of the nominal contact area, i.e. for physical reasonable loads. The authors also prove that, at high separation, all multiasperity contact models, which take into account the influence of summit curvature variation as a function of summit height, necessarily converge to a (slightly) improved version of the GW model, which, therefore, remains one of the most important milestones in the field of contact mechanics of rough surfaces.

  3. Nanotribology and Nanoscale Friction

    SciTech Connect

    Guo, Yi; Qu, Zhihua; Braiman, Yehuda; Zhang, Zhenyu; Barhen, Jacob

    2008-01-01

    Tribology is the science and technology of contacting solid surfaces in relative motion, including the study of lubricants, lubrication, friction, wear, and bearings. It is estimated that friction and wear cost the U.S. economy 6% of the gross national product (Persson, 2000). For example, 5% of the total energy generated in an automobile engine is lost to frictional resistance. The study of nanoscale friction has a technological impact in reducing energy loss in machines, in microelectromechanical systems (MEMS), and in the development of durable, low-friction surfaces and ultra-thin lubrication films.

  4. A search for T Tauri stars and related objects: Archival photometry of candidate variables in V733 Cep field

    NASA Astrophysics Data System (ADS)

    Jurdana-Šepić, R.; Poljančić Beljan, I.

    Searching for T Tauri stars or related early type variables we carried out a BVRI photometric measurements of five candidates with positions within the field of the pre-main sequence object V733 Cephei (Persson's star) located in the dark cloud L1216 near to Cepheus OB3 Association: VES 946, VES 950, NSV 14333, NSV 25966 and V385 Cep. Their magnitudes are determined on the plates from Asiago Observatory historical photographic archive exposed 1971 - 1978. We provide finding charts for program stars and comparison sequence stars, magnitude estimations, magnitude mean values and BVR_cI_c light curves of program stars.

  5. Infrared recombination lines of hydrogen from young objects in the southern Galactic plane

    NASA Technical Reports Server (NTRS)

    Beck, Sara C.; Fischer, Jacqueline; Smith, Howard A.

    1991-01-01

    Near infrared recombination lines of hydrogen are observed in twelve young objects in the southern Galactic plane. The sample includes Herbig-Haro objects and IRAS dark-cloud point sources from the 1987 catalog of Persson and Campbell. In four of the IRAS sources two or three infrared lines are measured, and their intensity ratios are consistent with models of optically thick ionized winds. The intrinsic line shapes, retrieved from maximum-entropy deconvolutions, indicate gas velocities of 100 km/s or more as expected from ionized winds. These sources are apparently embedded pre-main-sequence objects with outflows. They include some of the brightest known YSOs.

  6. In-situ X-ray diffraction studies of the phase transformations and structural states of B2, R and B19′ phases in Ti{sub 49.5}Ni{sub 50.5} alloy

    SciTech Connect

    Ostapenko, Marina G.; Meisner, Ludmila L.; Lotkov, Aleksandr I. Gudimova, Ekaterina Y.; Zakharova, Margarita A.

    2015-10-27

    The martensitic transformation, Debye–Waller factor, mean-square atomic displacements and the coefficient of thermal expansion on cooling of the Ti{sub 49.5}Ni{sub 50.5} shape memory alloy were examined using in-situ X-ray diffraction. It was revealed B2→R (T{sub R} ≡ T = 273 ± 10 K) along with B2→B19’ (M{sub s} ≡ T = 273 ± 10 K) transitions occur. It was found that Debye–Waller factor and mean-square displacement of B2 phase undergo significant increase as functions of temperature when phase transition B2→R and B2→B19’ take place. The analysis of the thermal expansion coefficient of the B2 phase indicates that the value of a increases almost linearly while cooling.

  7. In-situ X-ray diffraction studies of the phase transformations and structural states of B2, R and B19' phases in Ti49.5Ni50.5 alloy

    NASA Astrophysics Data System (ADS)

    Ostapenko, Marina G.; Meisner, Ludmila L.; Lotkov, Aleksandr I.; Zakharova, Margarita A.; Gudimova, Ekaterina Y.

    2015-10-01

    The martensitic transformation, Debye-Waller factor, mean-square atomic displacements and the coefficient of thermal expansion on cooling of the Ti49.5Ni50.5 shape memory alloy were examined using in-situ X-ray diffraction. It was revealed B2→R (TR ≡ T = 273 ± 10 K) along with B2→B19' (Ms ≡ T = 273 ± 10 K) transitions occur. It was found that Debye-Waller factor and mean-square displacement of B2 phase undergo significant increase as functions of temperature when phase transition B2→R and B2→B19' take place. The analysis of the thermal expansion coefficient of the B2 phase indicates that the value of a increases almost linearly while cooling.

  8. Water-level altitudes in wells completed in the Jasper aquifer, greater Houston area, Texas, Spring 2000

    USGS Publications Warehouse

    Coplin, L.S.

    2001-01-01

    This report, prepared in cooperation with the Harris-Galveston Coastal Subsidence District, presents a map showing the approximate water-level altitudes in spring 2000 in wells completed in the Jasper aquifer (back of page). The most recent previously published water-level-altitude map for the Jasper aquifer in the region is by Popkin (1971). The study area includes Montgomery County and parts of Harris, Waller, Grimes, and Walker Counties.

  9. Comparing ultrafast surface and bulk heating using time-resolved electron diffraction

    SciTech Connect

    Streubühr, C.; Kalus, A.; Zhou, P. Kammler, M.; Linde, D. von der; Ligges, M.; Hanisch-Blicharski, A.; Bovensiepen, U.; Horn-von Hoegen, M.

    2014-04-21

    From measurements of the transient Debye-Waller effect in Bismuth, we determine the buildup time of the random atomic motion resulting from the electronic relaxation after short pulse laser excitation. The surface sensitive reflection high energy electron diffraction and transmission electron diffraction yield a time constant of about 12 ps and 3 ps, respectively. The different energy transfer rates indicate relatively weak coupling between bulk and surface vibrational modes.

  10. Centenary of tele-electrocardiography and telephonocardiography.

    PubMed

    Hjelm, N M; Julius, H W

    2005-01-01

    In the history of electrocardiography the names of two physiologists stand out: Augustus Waller (1865-1922) and Willem Einthoven (1860-1927). Waller was the first to show that the beating heart produces a weak electric potential, which can be registered by a measuring device connected to electrodes attached to the skin. Einthoven developed a 'string' galvanometer, which was much faster and more sensitive than the system used by Waller. Einthoven's electrocardiograph was ready for use in 1903. To facilitate investigations of patients Einthoven connected his instrument to the Academic Hospital in Leyden, by a telephone line, as suggested by his engineering colleague Johannes Bosscha in Delft. The first successful tele-electrocardiogram was transmitted on Sunday 22 March 1905. The heart tones were registered by wiring a specially developed microphone placed on the subject's chest to another string galvanometer. The event was therefore a first both for tele-electrocardiography and for telephonocardiography. We are still awaiting the full-scale implementation of these achievements, 100 years later. PMID:16238834

  11. Annual compilation and analysis of hydrologic data for urban studies in the Austin, Texas Metropolitan Area, 1971

    USGS Publications Warehouse

    Tovar, F.H.

    1973-01-01

    The U.S. Geological Survey, in cooperation with the Texas Water Development Board, began hydrologic studies in the Austin urban area in 1954. The objectives of this project are as follows: 1. To determine the effects of progressive urbanization on infiltration, rates of peak discharge, and rainfall-runoff relations in the Waller Creek watershed. 2. To provide rainfall-and-runoff data from the rural Wilbarger Creek watershed to be used for comparative purposes in determining the effects of existing and progressive urbanization in the Waller Creek watershed. 3. To provide applied research facilities for studies at the University of Texas at Austin. The purpose of this report is to present rainfall-and-runoff data for the Waller Creek and Wilbarger Creek study areas for the 1971 water year (October 1, 1970, to September 30, 1971). To facilitate the publication and distribution of this report at the earliest feasible time, certain material has been included that does not conform to the formal publication standards of the U.S. Geological Survey.

  12. Physical properties of asteroid dust bands and their sources

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Vokrouhlický, David; Bottke, William F.; Sykes, Mark

    2006-03-01

    Disruptive collisions in the main belt can liberate fragments from parent bodies ranging in size from several micrometers to tens of kilometers in diameter. These debris bodies group at initially similar orbital locations. Most asteroid-sized fragments remain at these locations and are presently observed as asteroid families. Small debris particles are quickly removed by Poynting-Robertson drag or comminution but their populations are replenished in the source locations by collisional cascade. Observations from the Infrared Astronomical Satellite (IRAS) showed that particles from particular families have thermal radiation signatures that appear as band pairs of infrared emission at roughly constant latitudes both above and below the Solar System plane. Here we apply a new physical model capable of linking the IRAS dust bands to families with characteristic inclinations. We use our results to constrain the physical properties of IRAS dust bands and their source families. Our results indicate that two prominent IRAS bands at inclinations ≈2.1° and ≈9.3° are byproducts of recent asteroid disruption events. The former is associated with a disruption of a ≈30-km asteroid occurring 5.8 Myr ago; this event gave birth to the Karin family. The latter came from the breakup of a large >100-km-diameter asteroid 8.3 Myr ago that produced the Veritas family. Using an N-body code, we tracked the dynamical evolution of ≈10 6 particles, 1 μm to 1 cm in diameter, from both families. We then used these results in a Monte Carlo code to determine how small particles from each population undergo collisional evolution. By computing the thermal emission of particles, we were able to compare our results with IRAS observations. Our best-fit model results suggest the Karin and Veritas family particles contribute by 5-9% in 10-60-μm wavelengths to the zodiacal cloud's brightness within 50° latitudes around the ecliptic, and by 9-15% within 10° latitudes. The high brightness of

  13. "small problems, Big Trouble": An Art and Science Collaborative Exhibition Reflecting Seemingly small problems Leading to Big Threats

    NASA Astrophysics Data System (ADS)

    Waller, J. L.; Brey, J. A.

    2014-12-01

    "small problems, Big Trouble" (spBT) is an exhibition of artist Judith Waller's paintings accompanied by text panels written by Earth scientist Dr. James A. Brey and several science researchers and educators. The text panels' message is as much the focus of the show as the art--true interdisciplinarity! Waller and Brey's history of art and earth science collaborations include the successful exhibition "Layers: Places in Peril". New in spBT is extended collaboration with other scientists in order to create awareness of geoscience and other subjects (i.e. soil, parasites, dust, pollutants, invasive species, carbon, ground water contaminants, solar wind) small in scale which pose significant threats. The paintings are the size of a mirror, a symbol suggesting the problems depicted are those we increasingly need to face, noting our collective reflections of shared current and future reality. Naturalistic rendering and abstract form in the art helps reach a broad audience including those familiar with art and those familiar with science. The goal is that gallery visitors gain greater appreciation and understanding of both—and of the sober content of the show as a whole. "small problems, Big Trouble" premiers in Wisconsin April, 2015. As in previous collaborations, Waller and Brey actively utilize art and science (specifically geoscience) as an educational vehicle for active student learning. Planned are interdisciplinary university and area high school activities linked through spBT. The exhibition in a public gallery offers a means to enhance community awareness of and action on scientific issues through art's power to engage people on an emotional level. This AGU presentation includes a description of past Waller and Brey activities: incorporating art and earth science in lab and studio classrooms, producing gallery and museum exhibitions and delivering workshops and other presentations. They also describe how walking the paths of several past earth science

  14. Circuit racing, track texture, temperature and rubber friction

    NASA Astrophysics Data System (ADS)

    Sharp, R. S.; Gruber, P.; Fina, E.

    2016-04-01

    Some general observations relating to tyre shear forces and road surfaces are followed by more specific considerations from circuit racing. The discussion then focuses on the mechanics of rubber friction. The classical experiments of Grosch are outlined and the interpretations that can be put on them are discussed. The interpretations involve rubber viscoelasticity, so that the vibration properties of rubber need to be considered. Adhesion and deformation mechanisms for energy dissipation at the interface between rubber and road and in the rubber itself are highlighted. The enquiry is concentrated on energy loss by deformation or hysteresis subsequently. Persson's deformation theory is outlined and the material properties necessary to apply the theory to Grosch's experiments are discussed. Predictions of the friction coefficient relating to one particular rubber compound and a rough surface are made using the theory and these are compared with the appropriate results from Grosch. Predictions from Persson's theory of the influence of nominal contact pressure on the friction coefficient are also examined. The extent of the agreement between theory and experiment is discussed. It is concluded that there is value in the theory but that it is far from complete. There is considerable scope for further research on the mechanics of rubber friction.

  15. Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

    NASA Astrophysics Data System (ADS)

    Yang, Chunyan; Persson, Bo

    2008-03-01

    We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load [1-4]. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the interfacial separation approaches to zero. The present results may be very important for soft solids, e.g., rubber, or for very smooth surfaces, where complete contact can be reached at moderate high loads without plastic deformation of the solids. References: [1] C. Yang and B.N.J. Persson, arXiv:0710.0276, (to appear in Phys. Rev. Lett.) [2] B.N.J. Persson, Phys. Rev. Lett. 99, 125502 (2007) [3] L. Pei, S. Hyun, J.F. Molinari and M.O. Robbins, J. Mech. Phys. Sol. 53, 2385 (2005) [4] M. Benz, K.J. Rosenberg, E.J. Kramer and J.N. Israelachvili, J. Phy. Chem. B.110, 11884 (2006)

  16. The resolution of inflammation: anti-inflammatory roles for NF-kappaB.

    PubMed

    Lawrence, Toby; Fong, Carol

    2010-04-01

    Inflammation is a salutary response to insult or injury that normally resolves with no detriment to the host. While the mechanisms and mediators that regulate the onset of inflammation have been well characterized we still know relatively little about the endogenous mechanisms that terminate the inflammatory response (Lawrence and Gilroy, 2007). Nuclear factor (NF)-kappaB is a generic term for a family of ubiquitous transcription factors with diverse physiological functions (Bonizzi and Karin, 2004; Caamano and Hunter, 2002). NF-kappaB transcription factors are formed by dimerisation of Rel proteins; RelA (p65), c-Rel, RelB, p50, p52. Various hetero or homodimers of Rel proteins can be formed in a tissue and stimulus specific manner, genetic evidence suggests these transcription factors have a critical role in cell survival and pro-inflammatory signalling pathways, which have been extensively reviewed elsewhere (Bonizzi and Karin, 2004; Caamano and Hunter, 2002). The critical role for NF-kappaB in pro-inflammatory gene expression has led to an enormous effort to develop inhibitors of this pathway for the treatment of chronic inflammation (Karin et al., 2004). However, recent research using modern molecular genetic approaches has revealed new anti-inflammatory roles for NF-kappaB that may have important implications for targeting this pathway in the treatment of inflammatory diseases. In this review we will discuss the emerging role of NF-kappaB in the resolution of inflammation and some of the potential mechanisms attributed to this function. PMID:20026420

  17. The Surface Water and Ocean Topography Mission: a mission concept to study the world's oceans and fresh water

    NASA Astrophysics Data System (ADS)

    Vaze, Parag; Albuys, Vincent; Esteban-Fernandez, Daniel; Lafon, Thierry; Lambin, Juliette; Mallet, Alain; Rodriguez, Ernesto

    2010-10-01

    The Surface Water and Ocean Topography (SWOT) is a planned satellite mission to study the world's oceans and terrestrial surface water bodies. The SWOT mission concept has been proposed jointly by the global Hydrology and Oceanography science communities to make the first global survey of the Earth's surface water, observe the fine details of the ocean's surface topography, and measure how water bodies change over time. SWOT was one of 15 missions listed in the 2007 National Research Council's Decadal Survey for Earth science as a mission that NASA should implement in the incoming decade. This mission concept builds upon the heritage of prior missions and technologies such as Topex/Poseidon, Jason-1/ 2, the Shuttle Radar Topography Mission (SRTM), and the initial development of the Wide Swatch Ocean Altimeter intended for the Ocean Surface Topography Mission/Jason-2. The key measurement capability for SWOT is provided by a Ka-band synthetic aperture radar interferometer (KaRIn). With an orbit altitude of 970 km, the KaRIn instrument provides a high-resolution swath width of 120 km enabling global coverage (~90%) of the world's ocean's and fresh water bodies. The KaRIn measurement is being designed to provide a spatial resolution of 1 km for the oceans (after on-board processing), and 100 m for land water, both at centimetric accuracy. An additional instrument suite similar to the Jason series will complement KaRIn: a Ku-band nadir altimeter, a Microwave Radiometer and Precision Orbit Determination (POD) systems. To enable this challenging measurement performance, the SWOT mission concept is designed to overcome several challenges, such as very high raw data rate (320 Mbps), large on-board data volumes, high power demand, stringent pointing and stability requirements, and ground data processing systems, to produce meaningful science data products to our user community. The SWOT mission concept is being developed as a cooperative effort between NASA and CNES. This

  18. Koronis binaries and the role of families in binary frequency

    NASA Astrophysics Data System (ADS)

    Merline, W. J.; Tamblyn, P. M.; Nesvorny, D.; Durda, D. D.; Chapman, C. R.; Dumas, C.; Owen, W. M.; Storrs, A. D.; Close, L. M.; Menard, F.

    2005-08-01

    Our ground-based adaptive optics observations of many larger Koronis members show no binaries, while our HST survey of smaller Koronis members (say smaller than 10 km) shows a surprising 20% binary fraction. Admittedly, this is from small-number statistics, but we nonetheless calculate a 99% confidence that the binary fraction is different from the 2% we observe among the larger (over 20km) main belt asteroids as a whole. In addition, we estimate that among the two young families (Karin and Veritas) that we surveyed for binaries in our HST Cy 13 program, the binary fraction appears to be less than 5%. These young families both have significantly smaller progenitors than the Koronis family. We have speculated that progenitor size may be a more important factor than age in determination of binary frequency. But here we suggest an alternative idea, that the binary fraction may be more related to what part of the family's size distribution is sampled. Our HST program targeted objects of the same physical sizes, but was clearly sampling further down the size distribution (to smaller sizes, relative to the largest remnant) in the Koronis sample than was the case for Karin and Veritas, which we sampled mostly at the larger sizes, relatively. Our SPH collision models are estimating the typical size-frequency distributions to be expected from catastrophic and non-catastrophic impact events. But they are also appear to be showing that the largest fragments from a collision are less likely to form binaries (as co-orbiting ejecta pairs) than are the smaller fragments. Thus, it might be expected that we would have found fewer binaries among Karin and Veritas than among the Koronis sample. In fact, models of the Karin breakup show binary formation to be unlikely in the size range measured. It some might be tempted to tie the small end of the main-belt binary population to the binaries seen among the NEAs (also small and also showing about 20% fraction), given the 20% fraction

  19. Order parameters from image analysis: a honeycomb example

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest H.; Bultheel, Adhemar; Egami, Takeshi

    2008-11-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera ligustica. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP 3 , to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP 3 and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP 3 from 0.33 to 0.60 and values of u from 0.59 to 0.69. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more ‘liquid-like’ than cells made on ‘foundation’ wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells. This is the first description of honeycomb utilizing the Debye-Waller Factor, and provides a complete analysis of the order in comb from a real-space order parameter and a reciprocal space order parameter. It is noted that the techniques used are general in nature and could be applied to any digital photograph of an ordered array.

  20. [100 years' of clinical electrocardiography].

    PubMed

    Bergovec, Mijo

    2003-01-01

    In 1903 Willem Einthoven published in Pflügers Arch his classic article on the investigation of human electrocardiogram by his string galvanometer. Many historians of medicine, Einthoven also marked that publication as the beginning of clinical electrocardiography. Many investigators like Galvani, Manteucci, Kölliker, Müller, Lipmann, Waller, Ader, Einthoven, Lewis, Wilson and others participated in creation and development of electrocardiogram. From that time electrocardiogram quickly became, and has remained the most essential diagnostic laboratory tool in investigation of heart diseases. The aim of this article is to remind us of the beginning of this part of cardiology 100 years ago. PMID:15209030

  1. Historical aspects of electrocardiography.

    PubMed

    Krikler, D M

    1987-08-01

    One hundred years ago, Augustus Desiré Waller recorded the human electrocardiogram for the first time, using a capillary electrometer. Electrocardiography only became clinically relevant in 1901 when Willem Einthoven devised his string galvanometer for this purpose. Sir Thomas Lewis was the key figure in showing the value of the electrocardiography for the diagnosis of disorders of cardiac rhythm and conduction, but many others amplified the technique to encompass the assessment of structural heart disease, especially when due to ischemia. Knowledge of their role and work gives us a better perspective when considering the development of surface electrocardiography. PMID:3319160

  2. Strangles: a pathogenic legacy of the war horse.

    PubMed

    Waller, Andrew S

    2016-01-23

    Strangles, characterised by pyrexia followed by abscessation of the lymph nodes of the head and neck, was first described in 1251 (Rufus 1251) and the causative agent, Streptococcus equi, was identified in 1888 (Schutz 1888). However, despite more than a century of research into this disease, strangles remains the most frequently diagnosed infection of horses with over 600 outbreaks being identified in the UK alone each year (Parkinson and others 2011). Here, Andrew Waller reviews some of the recent advances in the understanding of the evolution of S equi and puts this into the context of preventing and resolving outbreaks of infection. PMID:26795860

  3. The material dependence of temperature measurement resolution in thermal scanning electron microscopy

    SciTech Connect

    Wu, Xiaowei; Hull, Robert

    2013-03-18

    Thermal scanning electron microscopy is a recently developed temperature mapping technique based on thermal diffuse scattering in electron backscatter diffraction in a scanning electron microscope. It provides nano-scale and non-contact temperature mapping capabilities. Due to the specific temperature sensitive mechanism inherent to this technique, the temperature resolution is highly material dependent. A thorough investigation of what material properties affect the temperature resolution is important for realizing the inherent temperature resolution limit for each material. In this paper, three material dependent parameters-the Debye-Waller B-factor temperature sensitivity, backscatter yield, and lattice constant-are shown to control the temperature resolution.

  4. Coverage-dependent quantum versus classical scattering of thermal neon atoms from Li/Cu(100).

    PubMed

    Maclaren, D A; Huang, C; Levi, A C; Allison, W

    2008-09-01

    We show that subtle variations in surface structure can enhance quantum scattering and quench atom-surface energy transfer. The scattering of thermal energy neon atoms from a lithium overlayer on a copper substrate switches between a classical regime, dominated by multiphonon interactions, and a quantum regime, dominated by elastic diffraction. The transition is achieved by simple tailoring of the lithium coverage and quantum scattering dominates only in the narrow coverage range of theta=0.3-0.6 ML. The results are described qualitatively using a modified Debye-Waller model that incorporates an approximate quantum treatment of the adsorbate-substrate vibration. PMID:19044885

  5. FEFF5: An ab initio multiple scattering XAFS code

    SciTech Connect

    Rehr, J.J.; Zabinsky, S.I.

    1992-12-31

    FEFF5 is an efficient automated code which calculates multiple scattering (MS) curved wave XAFS spectra for molecules and solids. The theoretical ingredients and approximations contained in the code are revised, with the aim of describing the how XAFS spectra are efficiently simulated. The FEFF5 code consists of 4 independent modules: a scattering potential and phase shift module, a path finder module, a scattering amplitude module and an XAFS module. Multiple scattering Debye-Waller factors are built in using a correlated Debye model.

  6. FEFF5: An ab initio multiple scattering XAFS code. [In FORTRAN 77

    SciTech Connect

    Rehr, J.J.; Zabinsky, S.I.

    1992-01-01

    FEFF5 is an efficient automated code which calculates multiple scattering (MS) curved wave XAFS spectra for molecules and solids. The theoretical ingredients and approximations contained in the code are revised, with the aim of describing the how XAFS spectra are efficiently simulated. The FEFF5 code consists of 4 independent modules: a scattering potential and phase shift module, a path finder module, a scattering amplitude module and an XAFS module. Multiple scattering Debye-Waller factors are built in using a correlated Debye model.

  7. Experimental Determination of Structure Factors of Titanium Aluminum and Silicon

    NASA Astrophysics Data System (ADS)

    Subramanian, Swaminathan

    Brittleness of TiAl has been attributed to strong directional bonding by a number of researchers. Their predictions have been based on theoretical calculations of electron charge density distribution. It is necessary to complement these predictions by experimental measurements. The work described in this thesis, aimed towards that end, involves measurement of Debye-Waller factors by four circle x-ray diffraction and of structure factors by energy filtered convergent beam electron diffraction CBED methods. Stoichiometric single crystals are required for the measurement of Debye-Waller factors by the four circle x-ray diffraction method. Because of constraints imposed by the phase diagram only non-stoichiometric single crystal of TiAl are available. Measurement of Debye-Waller parameters have been attempted by using aluminum rich TiAl single crystals of compositions Ti54at%Al and Ti56at%Al. The symmetry of L1_0 structure of TiAl dictates that all reflections with Miller indices (hkl) not satisfying the condition h + k = 2n should be extinct. However, during the x-ray diffraction experiments diffuse diffracted intensities were observed for reflections of h + k = 2n + 1 type. This indicates the possibility of occupation of the excess Al atoms on the Ti-sites. If the excess Al atom preferentially occupies one of the Ti-sites, it would lead to the formation of L1_2 type TiAl_3 unit cells within the TiAl lattice. This notion has been further verified by least-squares refinement of the data obtained from Ti54at%Al single crystal. Also Debye-Waller factor values were different for equivalent Ti-sites in TiAl. The CBED method was developed for accurate structure factor measurement. Factors such as limitation due to the angular resolution of the aperture and complex matrix and perturbation treatment of absorption have been considered. Computer routines, incorporating these factors, have been developed for the calculation of CBED patterns and for matching the rocking curves

  8. Quasi-elastic neutron scattering studies of protein dynamics. Progress report, November 1, 1992--May 25, 1993

    SciTech Connect

    Rorschach, H.E.

    1993-05-25

    Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.

  9. Quasi-elastic neutron scattering studies of protein dynamics

    SciTech Connect

    Rorschach, H.E.

    1993-05-25

    Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.

  10. Review of the highlights of X-ray studies of liquid metal surfaces

    SciTech Connect

    Pershan, P. S.

    2014-12-14

    X-ray studies of the interface between liquid metals and their coexisting vapor are reviewed. After a brief discussion of the few elemental liquid metals for which the surface Debye-Waller effect is sufficiently weak to allow measurement, this paper will go on to discuss the various types of surface phenomena that have been observed for liquid metal alloys. These include surface adsorption, surface freezing, surface aggregation of nm size atomic clusters, and surface chemistry that leads to new 3D crystalline phases.

  11. Making babies without sex: the law and the profits.

    PubMed

    Annas, G J

    1984-12-01

    The author reviews scientific and societal developments in artificial reproductive technologies during the past year in the U.S., the United Kingdom, and Australia. Successful births resulted from surrogate embryo transfer and from transfer of an embryo following in vivo fertilization. Recommendations on social policy were made by Australia's Waller Committee, Britain's Warnock Committee, and U.S. congressional hearings. Annas stresses the need to define parenthood and restrict commercialization of childbearing through the enactment of legislation, the promulgation of guidelines for sound clinical practice, and the establishment of an interdisciplinary body to monitor developments and the need for further regulation. PMID:6507700

  12. Slow Wave Conduction Patterns in the Stomach: From Waller’s Foundations to Current Challenges

    PubMed Central

    2015-01-01

    This review provides an overview of our understanding of motility and slow wave propagation in the stomach. It begins by reviewing seminal studies conducted by Walter Cannon and Augustus Waller on in vivo motility and slow wave patterns. Then our current understanding of slow wave patterns in common laboratory animals and humans is presented. The implications of slow wave dysrhythmic patterns that have been recorded in animals and patients suffering from gastroparesis are discussed. Finally, current challenges in experimental methods and techniques, slow wave modulation and the use of mathematical models are discussed. PMID:25313679

  13. The effects of urbanization on floods in the Austin metropolitan area, Texas

    USGS Publications Warehouse

    Veenhuis, J.E.; Gannett, D.G.

    1986-01-01

    The effects of urbanization on flood peaks in streams in the Austin metropolitan area Texas were studied in two separate analyses. In the first analysis, annual peak discharge records at 13 streamflow gaging sites were used to compute a recorded flood frequency relation for each site. Rainfall and streamflow data for 10 to 20 storms for each of these sites were used to simulate 55 annual peak discharges. These simulated discharges also were used to develop a flood frequency relation at each site. The flood frequency relations from recorded and generated data were then combined by weighting the recorded flood frequency by the years of record at each site to produce a combined (or weighted) flood frequency at each site. Flood frequencies for all 13 sites were subsequently regressed against basin characteristics at each site to determine possible effects of urbanization. The regression analysis of the combined flood frequency data for the 13 sites yielded an equation for estimating floods of a given recurrence interval at ungaged sites in the Austin area, as a function of the contributing drainage area, the total impervious area percentage, and basin shape. The regression equation estimates that a near fully developed hypothetical drainage basin (impervious area percentage, 45%) would have discharges for the 2 yr and 100 yr recurrence interval that are 99% and 73% greater, respectively, than discharges for those frequencies from a rural drainage basin (impervious percentage, 0). In the second analysis, records at one streamflow gaging site on Waller Creek were analyzed for changes in rainfall-runoff and flood frequency relations due to urbanization. Annual peak discharges from 1956 to 1980 and data from a total of 80 storms at the Waller Creek site were analyzed. Both analyses showed increases comparable to those predicted using the equations developed from the 13-station analysis. The last 14 years of record (the near fully developed land use stage for the Waller

  14. Anomalous behavior of LEED beam intensity during annealing

    NASA Astrophysics Data System (ADS)

    Fu, Tsu-Yi; Liu, T. F.; Su, C. W.; Shern, C. S.; Chen, R. H.

    2000-10-01

    Low-energy electron diffraction was used to study the annealing effects of 1 ML Ag on the ultra-thin-film Co/Pt (111). The behavior of the specular beam intensity versus temperature is anomalous. Besides the normal Debye-Waller effect, a bend occurs at 550 K, and a dramatic increase occurs at a higher temperature. A corresponding study by Auger electron spectroscopy and ultraviolet photoelectron spectroscopy indicates that the bend results from the Co inter-diffusion. The anomalous increase indicates that a more stable state forms at a higher temperature. The Co coverage plays an important role in determining the turning temperature. Possible mechanisms are discussed.

  15. Higher-Order-Mode Diagnostics and Suppression in Superconducting Cavities (HOMSC12)

    NASA Astrophysics Data System (ADS)

    Jones, Roger M.

    2014-01-01

    From the 25th of June through Wednesday lunchtime of the 27th of June 2012 the Cockcroft Institute and ASTeC hosted an ICFA supported mini workshop on Higher-Order-Mode Diagnostics and Suppression in Superconducting Cavities (HOMSC12). The local organizing committee for this international workshop was chaired by S. Buckley (ASTeC/STFC), conference administration by S. Waller (ASTeC/STFC), and the scientific program committee by R.M. Jones (Cockcroft Institute/University of Manchester).

  16. Rubber friction and tire dynamics.

    PubMed

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms. PMID:21406818

  17. Rubber friction and tire dynamics

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2011-01-01

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  18. VizieR Online Data Catalog: Distant radio galaxies in southern hemisphere (Bryant+, 2009)

    NASA Astrophysics Data System (ADS)

    Bryant, J. J.; Broderick, J. W.; Johnston, H. M.; Hunstead, R. W.; Gaensler, B. M.; De Breuck, C.

    2015-06-01

    Radio images were obtained with the Australia Telescope Compact Array (ATCA) in several runs in 2003-06. Both 1384- and 2368-MHz images were needed to pinpoint the K-band identification. Higher resolution observations were obtained for 29 sources on UT 2008 January 16-20. Our initial Ks-band imaging was begun on the 3.9-m Anglo-Australian Telescope's (AAT) Infrared Imager and Spectrograph (IRIS2) detector on two observing runs on 2004 August 3-5 and 2005 June 21-24. We observed 126 targets in Ks-band with Persson's Auxiliary Nasmyth Infrared Camera (PANIC;) on the 6.5-m Magellan Baade telescope at Las Campanas Observatory on 2006 June 11-13, 2006 November 8-10 and 2007 April 2-4. (2 data files).

  19. Rubber friction on road surfaces: Experiment and theory for low sliding speeds.

    PubMed

    Lorenz, B; Oh, Y R; Nam, S K; Jeon, S H; Persson, B N J

    2015-05-21

    We study rubber friction for tire tread compounds on asphalt road surfaces. The road surface topographies are measured using a stylus instrument and atomic force microscopy, and the surface roughness power spectra are calculated. The rubber viscoelastic modulus mastercurves are obtained from dynamic mechanical analysis measurements and the large-strain effective modulus is obtained from strain sweep data. The rubber friction is measured at different temperatures and sliding velocities, and is compared to the calculated data obtained using the Persson contact mechanics theory. We conclude that in addition to the viscoelastic deformations of the rubber surface by the road asperities, there is an important contribution to the rubber friction from shear processes in the area of contact. The analysis shows that the latter contribution may arise from rubber molecules (or patches of rubber) undergoing bonding-stretching-debonding cycles as discussed in a classic paper by Schallamach. PMID:26001467

  20. Rubber friction on road surfaces: Experiment and theory for low sliding speeds

    SciTech Connect

    Lorenz, B.; Persson, B. N. J.; Oh, Y. R.; Nam, S. K.; Jeon, S. H.

    2015-05-21

    We study rubber friction for tire tread compounds on asphalt road surfaces. The road surface topographies are measured using a stylus instrument and atomic force microscopy, and the surface roughness power spectra are calculated. The rubber viscoelastic modulus mastercurves are obtained from dynamic mechanical analysis measurements and the large-strain effective modulus is obtained from strain sweep data. The rubber friction is measured at different temperatures and sliding velocities, and is compared to the calculated data obtained using the Persson contact mechanics theory. We conclude that in addition to the viscoelastic deformations of the rubber surface by the road asperities, there is an important contribution to the rubber friction from shear processes in the area of contact. The analysis shows that the latter contribution may arise from rubber molecules (or patches of rubber) undergoing bonding-stretching-debonding cycles as discussed in a classic paper by Schallamach.

  1. Rubber friction on road surfaces: Experiment and theory for low sliding speeds

    NASA Astrophysics Data System (ADS)

    Lorenz, B.; Oh, Y. R.; Nam, S. K.; Jeon, S. H.; Persson, B. N. J.

    2015-05-01

    We study rubber friction for tire tread compounds on asphalt road surfaces. The road surface topographies are measured using a stylus instrument and atomic force microscopy, and the surface roughness power spectra are calculated. The rubber viscoelastic modulus mastercurves are obtained from dynamic mechanical analysis measurements and the large-strain effective modulus is obtained from strain sweep data. The rubber friction is measured at different temperatures and sliding velocities, and is compared to the calculated data obtained using the Persson contact mechanics theory. We conclude that in addition to the viscoelastic deformations of the rubber surface by the road asperities, there is an important contribution to the rubber friction from shear processes in the area of contact. The analysis shows that the latter contribution may arise from rubber molecules (or patches of rubber) undergoing bonding-stretching-debonding cycles as discussed in a classic paper by Schallamach.

  2. Metallicity determinations for globular clusters through spectrophotometry of their integrated light

    NASA Astrophysics Data System (ADS)

    Brodie, J. P.; Hanes, D. A.

    1986-01-01

    Using an appropriately weighted combination of 16 indices of absorption line strength measured in low-dispersion spectra of the integrated light of globular clusters, metallicities Fe/H are determined for thirty-six clusters in the Galaxy. The results confirm the suggestion that Zinn's (1980) scale suffers a systematic error in the region of intermediate metallicity and support an explanation in which his metallicity-indicative Q39 index has been diluted by excess ultraviolet light in clusters with anomalously rich blue horizontal branches. The methods, which involve the measurement of spectral features arising from many species, produce estimates of metallicity which are insensitive to this problem. Good agreement is found with several recent studies, but a disagreement is noted for the most metal-rich clusters studied by Frogel, Cohen, and Persson (1983). Finally, a similar method with a modified calibration is used to determine metallicities for the nuclei of six galaxies.

  3. A New Approach for Imposing Artificial Viscosity for Explicit Discontinuous Galerkin Scheme

    NASA Astrophysics Data System (ADS)

    See, Yee Chee; Lv, Yu; Ihme, Matthias

    2014-11-01

    The development of high-order numerical methods for unstructured meshes has been a significant area of research, and the discontinuous Galerkin (DG) method has found considerable interest. However, the DG-method exhibits robustness issues in application to flows with discontinuities and shocks. To address this issue, an artificial viscosity method was proposed by Persson et al. for steady flows. Its extension to time-dependent flows introduces substantial time-step restrictions. By addressing this issue, a novel method, which is based on an entropy formulation, is proposed. The resulting scheme doesn't impose restrictions on the CFL-constraint. Following a description of the formulation and the evaluation of the stability, this newly developed artificial viscosity scheme is demonstrated in application to different test cases.

  4. Preventing ultimate harm as the justification for biomoral modification.

    PubMed

    Murphy, Timothy F

    2015-06-01

    Most advocates of biogenetic modification hope to amplify existing human traits in humans in order to increase the value of such traits as intelligence and resistance to disease. These advocates defend such enhancements as beneficial for the affected parties. By contrast, some commentators recommend certain biogenetic modifications to serve social goals. As Ingmar Persson and Julian Savulescu see things, human moral psychology is deficient relative to the most important risks facing humanity as a whole, including the prospect of Ultimate Harm, the point at which worthwhile life is forever impossible on the planet. These risks can be mitigated, they say, by enhancing moral psychology in novel ways. Persson and Savulescu argue that some parents should modify the underlying biogenetics of their children's moral psychology, if such measures were safe and effective, but they admit these interventions may not decouple humanity from Ultimate Harm. Neither are these modifications the only options, they concede, for addressing risks to humanity. Even with these concessions, saving humanity from itself is a fairly poor reason to modify the moral psychology of children. In most ways, adults would be better candidates, morally speaking, for modifications of psychology. Even then, there is no direct link between morally enhanced human beings and the hoped-for effect of better protection from Ultimate Harm. Asserting a general duty of all to contribute to the avoidance of Ultimate Harm is a better moral strategy than intervening in the moral psychology of some, even though meeting that duty may involve substantial interference with the free exercise of one's interests. PMID:25186171

  5. Koronis asteroid dust within Antarctic ice

    NASA Astrophysics Data System (ADS)

    Genge, Matthew J.

    2008-09-01

    Here I report the first discovery of large numbers of ordinarychondrite-derived micro-meteorites (MMs) recovered fromAntarctic ice. Ordinary chondrite-derived MMs comprise70% coarse-grained igneous particles and are identified on thebasis of their distribution of petrologic types, accessory mineralogy,and minor element compositions, all of which are very similarto those of millimeter-sized igneous objects known as chondrules,from ordinary chondrites, and largely distinct from those ofother meteorite groups. The majority of ordinary chondrite-derivedMMs are unequilibrated materials; however, 15% are equilibrated,indicating parent body metamorphism, and have compositions consistentwith both H (high iron) and L (low iron) chondrites. The totalabundance of ordinary chondrite-derived MMs of ~18% issimilar to predictions by numerical calculations for the abundanceof dust generated by the recent breakup of the Karin group asteroidsof the Koronis asteroid family, suggesting that these asteroidsare the main source of the particles. These MMs represent thefirst to be associated with a known asteroid and imply thatthe Karin group progenitor asteroid was a rubble-pile asteroidthat sampled different depths within the original internallymetamorphosed Koronis parent body.

  6. Order Parameters for Two-Dimensional Networks

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi

    2007-10-01

    We derive methods that explain how to quantify the amount of order in ``ordered'' and ``highly ordered'' porous arrays. Ordered arrays from bee honeycomb and several from the general field of nanoscience are compared. Accurate measures of the order in porous arrays are made using the discrete pair distribution function (PDF) and the Debye-Waller Factor (DWF) from 2-D discrete Fourier transforms calculated from the real-space data using MATLAB routines. An order parameter, OP3, is defined from the PDF to evaluate the total order in a given array such that an ideal network has the value of 1. When we compare PDFs of man-made arrays with that of our honeycomb we find OP3=0.399 for the honeycomb and OP3=0.572 for man's best hexagonal array. The DWF also scales with this order parameter with the least disorder from a computer-generated hexagonal array and the most disorder from a random array. An ideal hexagonal array normalizes a two-dimensional Fourier transform from which a Debye-Waller parameter is derived which describes the disorder in the arrays. An order parameter S, defined by the DWF, takes values from [0, 1] and for the analyzed man-made array is 0.90, while for the honeycomb it is 0.65. This presentation describes methods to quantify the order found in these arrays.

  7. Structural Physics of Bee Honeycomb

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi

    2008-03-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP3, to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP3 and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP3 from 0.33 to 0.60 and values of u from 0.83 to 0.98. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more `liquid-like' than cells made on `foundation' wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells.

  8. Quantum scattering of neon from a nanotextured surface.

    PubMed

    Levi, A C; Huang, C; Allison, W; Maclaren, D A

    2009-06-01

    Phonon exchange is the usual cause of decoherence in atom-surface scattering. By including quantum effects in the treatment of Debye-Waller scattering, we show that phonon exchange becomes ineffective when the relevant phonon frequencies are high. The result explains the surprising observation of strong elastic scattering of Ne from a Cu(100) surface nanotextured with a c(2 × 2) Li adsorbate structure. We extend a previous model to describe the phonon spectra by an Einstein oscillator component with an admixture of a Debye spectrum. The Einstein oscillator represents the dominant, high frequency vibration of the adsorbate, normal to the surface, while the Debye spectrum represents the substrate contribution. Neon scattering is so slow that exciting the adsorbate mode has a low probability and is impossible if the incident energy is below the threshold. Thus, adsorbate vibrations are averaged out. A theoretical discussion and calculation shows that under such circumstances the vibrations of a light adsorbate do not contribute to the Debye-Waller effect, with the result that Ne scattering at thermal energies is quantum mechanical and largely elastic, explaining the high reflectivity and the diffraction peaks observed experimentally. PMID:21715773

  9. Vibrational Properties of Nanocrystals from the Debye Scattering Equation

    PubMed Central

    Scardi, P.; Gelisio, L.

    2016-01-01

    One hundred years after the original formulation by Petrus J.W. Debije (aka Peter Debye), the Debye Scattering Equation (DSE) is still the most accurate expression to model the diffraction pattern from nanoparticle systems. A major limitation in the original form of the DSE is that it refers to a static domain, so that including thermal disorder usually requires rescaling the equation by a Debye-Waller thermal factor. The last is taken from the traditional diffraction theory developed in Reciprocal Space (RS), which is opposed to the atomistic paradigm of the DSE, usually referred to as Direct Space (DS) approach. Besides being a hybrid of DS and RS expressions, rescaling the DSE by the Debye-Waller factor is an approximation which completely misses the contribution of Temperature Diffuse Scattering (TDS). The present work proposes a solution to include thermal effects coherently with the atomistic approach of the DSE. A deeper insight into the vibrational dynamics of nanostructured materials can be obtained with few changes with respect to the standard formulation of the DSE, providing information on the correlated displacement of vibrating atoms. PMID:26916341

  10. Vibrational properties of nanocrystals from the Debye Scattering Equation

    DOE PAGESBeta

    Scardi, P.; Gelisio, L.

    2016-02-26

    One hundred years after the original formulation by Petrus J.W. Debije (aka Peter Debye), the Debye Scattering Equation (DSE) is still the most accurate expression to model the diffraction pattern from nanoparticle systems. A major limitation in the original form of the DSE is that it refers to a static domain, so that including thermal disorder usually requires rescaling the equation by a Debye-Waller thermal factor. The last is taken from the traditional diffraction theory developed in Reciprocal Space (RS), which is opposed to the atomistic paradigm of the DSE, usually referred to as Direct Space (DS) approach. Besides beingmore » a hybrid of DS and RS expressions, rescaling the DSE by the Debye-Waller factor is an approximation which completely misses the contribution of Temperature Diffuse Scattering (TDS). The present work proposes a solution to include thermal effects coherently with the atomistic approach of the DSE. Here, a deeper insight into the vibrational dynamics of nanostructured materials can be obtained with few changes with respect to the standard formulation of the DSE, providing information on the correlated displacement of vibrating atoms.« less

  11. Local Structure and Vibrational Properties of alpha-Pu, alpha-U, and the alpha-U Charge Density Wave

    SciTech Connect

    Nelson, E J; Allen, P G; Blobaum, K M; Wall, M A; Booth, C H

    2004-08-10

    The local atomic environment and vibrational properties of atoms in monoclinic pure {alpha}-plutonium as well as orthorhombic pure {alpha}-uranium and its low-temperature charge-density-wave (CDW) modulation are examined by extended x-ray absorption fine structure spectroscopy (EXAFS). Pu L{sub III}-edge and U L{sub III}-edge EXAFS data measured at low temperatures verify the crystal structures of {alpha}-U and {alpha}-Pu samples previously determined by x-ray diffraction and neutron scattering. Debye-Waller factors from temperature-dependent EXAFS measurements are fit with a correlated Debye model. The observed Pu-Pu bond correlated Debye temperature of {theta}{sub cD}({alpha}-Pu) = 162 {+-} 5 K for the pure {alpha}-Pu phase agrees with our previous measurement of the correlated Debye temperature of the gallium-containing {alpha}'-Pu phase in a mixed phase 1.9 at% Ga-doped {alpha}'-Pu/{delta}-Pu alloy. The temperature dependence of the U-U nearest neighbor Debye-Waller factor exhibits a sharp discontinuity in slope near T{sub CDW} = 43 K, the transition temperature at which the charge-density wave (CDW) in {alpha}-U condenses from a soft phonon mode along the (100) direction. Our measurement of the CDW using EXAFS is the first observation of the structure of the CDW in polycrystalline {alpha}-U. The different temperature dependence of the Debye-Waller factor for T < T{sub CDW} can be modeled by the change in bond length distributions resulting from condensation of the charge density wave. For T > T{sub CDW}, the observed correlated Debye temperature of {theta}{sub cD}({alpha}-U) = 199 {+-} 3 K is in good agreement with other measurements of the Debye temperature for polycrystalline {alpha}-U. CDW structural models fit to the {alpha}-U EXAFS data support a squared CDW at the lowest temperatures, with a displacement amplitude of {var_epsilon} = 0.05 {+-} 0.02 {angstrom}.

  12. Local structure and vibrational properties of alpha-Pu, alpha-Uand the alpha-U charge density wave

    SciTech Connect

    Nelson, E.J.; Allen, P.G.; Blobaum, K.J.M.; Wall, W.A.; Booth, C.H.

    2004-08-10

    The local atomic environment and vibrational properties of atoms in monoclinic pure {alpha}-plutonium as well as orthorhombic pure a-uranium and its low-temperature charge-density-wave (CDW) modulation are examined by extended x-ray absorption fine structure spectroscopy (EXAFS). Pu L{sub III}-edge and U L{sub III}-edge EXAFS data measured at low temperatures verify the crystal structures of {alpha}-U and {alpha}-Pu samples previously determined by x-ray diffraction and neutron scattering. Debye-Waller factors from temperature-dependent EXAFS measurements are fit with a correlated Debye model. The observed Pu-Pu bond correlated Debye temperature of {theta}{sub cD}({alpha}-Pu) = 162 {+-} 5 K for the pure {alpha}-Pu phase agrees with our previous measurement of the correlated Debye temperature of the gallium-containing {alpha}{prime}-Pu phase in a mixed phase 1.9 at% Ga-doped {alpha}{prime}-Pu/{delta}-Pu alloy. The temperature dependence of the U-U nearest neighbor Debye-Waller factor exhibits a sharp discontinuity in slope near T{sub CDW} = 43 K, the transition temperature at which the charge-density wave (CDW) in {alpha}-U condenses from a soft phonon mode along the (100) direction. Our measurement of the CDW using EXAFS is the first observation of the structure of the CDW in polycrystalline {alpha}-U. The different temperature dependence of the Debye-Waller factor for T < T{sub CDW} can be modeled by the change in bond length distributions resulting from condensation of the charge density wave. For T > T{sub CDW}, the observed correlated Debye temperature of {theta}{sub cD}({alpha}-U) = 199 {+-} 3 K is in good agreement with other measurements of the Debye temperature for polycrystalline {alpha}-U. CDW structural models fit to the {alpha}-U EXAFS data support a squared CDW at the lowest temperatures, with a displacement amplitude of {var_epsilon} = 0.05 {+-} 0.02 {angstrom}.

  13. Persistent discourses in physics education: gender neutrality and the gendering of competence

    NASA Astrophysics Data System (ADS)

    Gonsalves, Allison

    2014-06-01

    In her article, Karin Due presents us with a contradiction in physics: the construction of physics as a symbolically masculine discipline alongside a simultaneous discourse of the "gender-neutrality" of the discipline. Due's article makes an important contribution to the study of the gendering of physics practices, particularly in group dynamics, and how this serves to simultaneously reinforce the two competing discourses of physics as a masculine discipline, and the discourse of physics as a gender neutral discipline. Due also suggests that an implication of this contradiction is a limited number of available positions for girls in physics compared to those available to boys. I wish to take up this observation and discuss how available positions for boys and girls in physics are related quite closely to two other concepts discussed in Due's article: competence and recognition.

  14. Origin of the Near-Ecliptic Circumsolar Dust Band

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Bottke, William F.; Vokrouhlický, David; Sykes, Mark; Lien, David J.; Stansberry, John

    2008-06-01

    The zodiacal dust bands are bright infrared (IR) strips produced by thermal emission from circumsolar rings of particles. Two of the three principal dust bands, known as β and γ, were previously linked to the recent asteroid collisions that produced groups of fragments, so-called asteroid families, near the orbits of (832) Karin and (490) Veritas. The origin of the third, near-ecliptic α band has been unknown until now. Here we report the discovery of a recent breakup of a >20 km diameter asteroid near α's originally suspected source location in the Themis family. Numerical modeling and observations of the α-band thermal emission from the Spitzer Space Telescope indicate that the discovered breakup is the source of α-band particles. The recent formation of all principal dust bands implies a significant time variability of the circumstellar debris disks.

  15. Perspectives on positioning, interaction, and learning in small-group discussion: possibilities for extending the analytic lens

    NASA Astrophysics Data System (ADS)

    Kittleson, Julie M.; Wilson, Rachel E.

    2014-06-01

    In this forum piece, we respond to Karin Due's study of social dynamics in groups of students in physics class and gender issues that play out in this context. We discuss two threads that appear in Due's paper: one pertains to patterns of talk within groups and how these patterns open up possibilities for learning, the other pertains to ways in which gender is constructed within groups and made visible via discourse. Our comments are intended to provide alternative ways of thinking about such issues. We hope to provide insight into how to deepen analyses of group dynamics and gender because research in both areas is important in terms of understanding how social contexts support and/or constrain learning, gender identity, and the like.

  16. Observations of Members of Very Young Asteroid Families

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Merline, W. J.; Nesvorny, D.; Tamblyn, P. M.; Young, E. F.

    2005-08-01

    Several asteroid families or clusters have been found [cf. D. Nesvorny et al. 2003, Ap.J. 591:486-497] to have very short dynamical ages. The Veritas family of C-type asteroids, Karin cluster within the S-type Koronis family, and the Iannini cluster (apparently S-type) formed about 8.3, 5.8, and <5 Myr ago, respectively. If one or more kinds of asteroidal processes (e.g. spin evolution, space weathering, devolatilization of near-surface materials, satellite formation and evolution) operate on timescales comparable with or slower than several Myr, then we may expect to observe different physical properties for members of these recently formed families than for older family members. During the first year of our multifaceted observing program, we have used numerous facilities (IRTF/MIRSI, IRTF/SPeX, HST, Spitzer, CTIO 0.9m, KPNO 0.9m and 2.1m, VLT AO, Gemini AO, and Keck AO), during 14 different runs, to obtain about 100 different observational datasets for members of the 3 young families plus numerous additional observations of controls (e.g. Themis family and non-Karin members of the Koronis family). Techniques employed include lightcurve photometry, visible colorimetry, near-IR spectral reflectance, thermal IR, and AO search for satellites. We discuss representative results from these observations. Theoretical synthesis of the data must await a more complete sampling of these family asteroids by the different techniques. This work is being supported primarily by the NASA Planetary Astronomy Program and by the observing facilities listed.

  17. Ultrafast interfacial electron transfer from the excited state of anchored molecules into a semiconductor

    NASA Astrophysics Data System (ADS)

    Gundlach, L.; Ernstorfer, R.; Willig, F.

    Ultrafast heterogeneous electron transfer (HET) from the excited singlet state of the large organic chromophore perylene into the inorganic semiconductor rutile TiO 2 was investigated with femtosecond time-resolved two-photon photoemission (TR-2PPE). The strength of the electronic interaction between the chromophore and the semiconductor was varied by inserting different anchor/bridge groups that functioned either as electronic wire or electronic tunnelling barrier. Both anchor groups, i.e. carboxylic and phosphonic acid, formed strong chemical bonds at the TiO 2 surface. The perylene chromophore with the different anchor/bridge groups was adsorbed from solution in a dedicated ultra-high-vacuum (UHV) chamber. The adsorption geometry of the chromophore perylene was determined from angle and polarization dependent two-photon photoemission (2PPE) signals and was found to be very different for the two different anchor/bridge groups. The measured adsorption geometries are compatible with recent DFT (density functional theory) calculations by P. Persson and co-workers [M. Nilsing, S. Lunell, P. Persson, L. Ojamäe, Phosphonic acid adsorption at the TiO 2 anatase (1 0 1) surface investigated by periodic hybrid HF-DFT computations, Surf. Sci. 582 (2005) 49-60]. Two different processes contributed to the TR-2PPE transients, firstly electron transfer from the chromophore to the electronic acceptor states on the surface and secondly escape of the electrons from the surface into the bulk of the semiconductor. The latter escape process was measured separately by making the interfacial electron injection process instantaneous when the chromophore catechol was employed in place of the perylene compounds. The thus measured electron escape behavior was governed by the same time constants that have recently been predicted by Prezhdo and coworkers from time dependent DFT calculations [W.R. Duncan, W.M. Stier, O.V. Prezhdo, Ab initio nonadiabatic molecular dynamics of the ultrafast

  18. Flat-ramp vs. convex-concave thrust geometries in a deformable hanging wall: new insights from analogue modeling experiments

    NASA Astrophysics Data System (ADS)

    Almeida, Pedro; Tomas, Ricardo; Rosas, Filipe; Duarte, Joao; Terrinha, Pedro

    2015-04-01

    Different modes of strain accommodation affecting a deformable hanging-wall in a flat-ramp-flat thrust system were previously addressed through several (sandbox) analog modeling studies, focusing on the influence of different variables, such as: a) thrust ramp dip angle and friction (Bonini et al, 2000); b) prescribed thickness of the hanging-wall (Koy and Maillot, 2007); and c) sin-thrust erosion (compensating for topographic thrust edification, e.g. Persson and Sokoutis, 2002). In the present work we reproduce the same experimental procedure to investigate the influence of two different parameters on hanging-wall deformation: 1) the geometry of the thrusting surface; and 2) the absence of a velocity discontinuity (VD) that is always present in previous similar analogue modeling studies. Considering the first variable we use two end member ramp geometries, flat-ramp-flat and convex-concave, to understand the control exerted by the abrupt ramp edges in the hanging-wall stress-strain distribution, comparing the obtain results with the situation in which such edge singularities are absent (convex-concave thrust ramp). Considering the second investigated parameter, our motivation was the recognition that the VD found in the different analogue modeling settings simply does not exist in nature, despite the fact that it has a major influence on strain accommodation in the deformable hanging-wall. We thus eliminate such apparatus artifact from our models and compare the obtained results with the previous ones. Our preliminary results suggest that both investigated variables play a non-negligible role on the structural style characterizing the hanging-wall deformation of convergent tectonic settings were such thrust-ramp systems were recognized. Acknowledgments This work was sponsored by the Fundação para a Ciência e a Tecnologia (FCT) through project MODELINK EXPL/GEO-GEO/0714/2013. Pedro Almeida wants to thank to FCT for the Ph.D. grant (SFRH/BD/52556/2014) under the

  19. Structure refinement of sub-cubic-mm volume sample at high pressures by pulsed neutron powder diffraction: application to brucite in an opposed anvil cell

    NASA Astrophysics Data System (ADS)

    Okuchi, Takuo; Tomioka, Naotaka; Purevjav, Narangoo; Abe, Jun; Harjo, Stefanus; Gong, Wu

    2014-04-01

    Neutron powder diffraction measurements of 0.9 mm3 of mixture of deuterated brucite and pressure medium were conducted at pressures to 2.8 GPa, using an opposed anvil cell and a medium-resolution diffractometer at Japan Proton Accelerator Research Complex pulsed neutron source. Spurious-free diffraction patterns were successfully obtained and refined to provide all structural parameters including Debye-Waller factors. Tilting of hydroxyl dipoles of brucite toward one of the three nearest-neighbor oxygen anions was confirmed to be substantial at pressure as low as 1.5 GPa. By this application, technical feasibility to analyze such a small sample has been newly established, which would be useful to extend the applications of neutron diffraction at high pressures.

  20. Molecular dynamics of an α-helical polypeptide: Temperature dependence and deviation from harmonic behavior

    PubMed Central

    Levy, Ronald M.; Perahia, David; Karplus, Martin

    1982-01-01

    The mean square amplitudes of atomic fluctuations for a polypeptide (decaglycine) α-helix evaluated from molecular dynamics simulations at seven temperatures between 5 and 300 K are compared with analytic harmonic results and with experimental values. Above 100 K the harmonic approximation significantly underestimates the amplitudes of the displacements. Analysis of the time dependence of the fluctuations shows that low-frequency modes (<75 cm-1) dominate the atomic fluctuations and that there is a contribution with a very long relaxation time (>10 ps). Quantum corrections to the amplitude of the fluctuations are found to be small above 50 K. The mean square amplitudes obtained from the molecular dynamics simulations are compared with the values derived from x-ray temperature (Debye-Waller) factors for metmyoglobin (80, 250, and 300 K) and ferrocytochrome c (300 K). PMID:16593164

  1. The origins of electrocardiography in Poland.

    PubMed

    Gryglewski, Ryszard W

    2015-06-01

    The progress of science and technology in the 19(th) century enabled better understanding of the electrical activity that occurs during a heartbeat. However, it was only the construction and introduction of the galvanometer that cleared the way for appropriate experimental and clinical studies. Marey, Waller, Wenckebach, Einthoven, and Pardee are just examples of the world's pioneers of electrocardiography. Polish researchers, including Cybulski, Eiger, Rzętkowski, Surzycki, and Latkowski, also contributed to the development of this area of study. The following article is a review aiming to reconstruct the origins of electrocardiography in Poland, both as a measurement method used in experiments and as a diagnostic tool in clinical studies conducted in the years preceding the outbreak of World War I. PMID:26336508

  2. Resuscitation great. Willem Einthoven: the development of the human electrocardiogram.

    PubMed

    Cajavilca, Christian; Varon, Joseph

    2008-03-01

    The electrocardiogram is one of the most commonly used diagnostic tools in healthcare. This ingenious device was developed and created in the early 1900s by Willem Einthoven, MD, PhD after studying the mechanisms of electromagnetism and Waller's capillary electrometer. Einthoven dedicated most of his research and clinical activities to improve the early versions of the electrical current recording medical devices. Einthoven's most notable invention was the string galvanometer which we now know as the electrocardiogram. Although the idea of using the string galvanometer as a diagnostic tool faced opposition by scientists and physicians of his time, he remained convinced of the potential of his machine to improve patient care. Einthoven's string galvanometer subsequently became the standard diagnostic tool for recognition and differentiation of heart conditions through the interpretation of cardiac waves, and has become standard practice in the field of resuscitation. In 1924, Einthoven received the Nobel Prize in Medicine for his development of the string galvanometer. PMID:18164799

  3. Willem Einthoven--inventor of electrocardiography.

    PubMed

    Schweitzer, P; Keller, S

    2002-12-01

    Willem Einthoven, the inventor of the string galvanometer electrocardiograph, was born in the Dutch East Indies, studied medicine in Utrecht Holland, and became chairman of the Department of Physiology at the University of Leiden. In 1924 he was awarded the Nobel Price for physiology and medicine. Einthoven became interested in electrophysiology after Waller's demonstration of the human electrogram using Lippmann's capillary electrometer. Because of important limitations of this device, Einthoven decided to construct the string galvanometer to be used for physiological research and in clinical medicine. Einthoven's main achievements in electrophysiology were the description of the normal ECG, some physiological effects on the ECG, the three ECG leads and the triangle rule. In 1906 in cooperation with the university hospital, Einthoven demonstrated the clinical usefulness of the electrocardiograph. PMID:12744012

  4. Approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-93 and 1992-93, and measured compaction, 1973-92, in the Houston-Galveston region, Texas

    USGS Publications Warehouse

    Kasmarek, Mark C.; Coplin, L.S.; Campodonico, Al

    1993-01-01

    This report is one in a series of reports that depict water-level changes since 1977 and compaction of subsurface material since 1973.  The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District and the City of Houston, and presents maps showing the approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-93 and 1992-93 (figs. 1-4), and measured compaction, 1973-92 (figs. 5 and 6), in the Houston-Galveston region.  The Houston-Galveston region includes Harris and Galveston Counties and adjacent parts of Brazoria, Fort Bend, Waller, Montgomery, Liberty, and Chambers Counties.

  5. Approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-94 and 1993-94, and measured compaction, 1973-93, in the Houston-Galveston region, Texas

    USGS Publications Warehouse

    Kasmarek, Mark C.; Coplin, L.S.; Santos, Horacio X.

    1994-01-01

    This report is one in a series of reports that depict water-level changes since 1977 and compaction of subsurface material since 1973.  The report was prepared in cooperation with the City of Houston and the Harris-Galveston Coastal Subsidence District, and presents maps showing the approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-94 and 1993-94 (figs. 1-4), extensometer site locations (fig. 5), and measured compaction, 1973-93 (fig. 6), in the Houston-Galveston region.  Water-level change maps were prepared previously by Kasmarek and others (1993).  The Houston-galveston region includes Harris and Galveston Counties and adjacent parts of Brazoria, Fort Bend, Waller, Montgomery, Liberty, and Chambers Counties.

  6. Approximate changes in water levels in wells completed in the Chicot and Evangeline aquifers, 1977-92 and 1991-92, and measured compaction, 1973-91 in the Houston-Galveston region, Texas.

    USGS Publications Warehouse

    Kasmarek, Mark C.; Barbie, Dana L.; Campodonico, Al

    1992-01-01

    This report is one in a series of reports that depict water-level changes since 1977 and compaction of subsurface material since 1973.  The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District and the City of Houston, and presents maps showing the approximate changes in water-levels in wells completed in the Chicot and Evangeline aquifers, 1977-92 and 1991-92 (figs. 1-4), and measured compations, 1973-91 (figs. 5 and 6), in the Houston-Galveston region.  The Houston-Galveston region includes Harris and Galveston Counties and adjacent parts of Brazoria, Fort Bend, Waller, Montgomery, Liberty, and Chambers Counties.

  7. A survey of global radiation damage to 15 different protein crystal types at room temperature: a new decay model

    PubMed Central

    Leal, Ricardo Miguel Ferraz; Bourenkov, Gleb; Russi, Silvia; Popov, Alexander N.

    2013-01-01

    The radiation damage rates to crystals of 15 model macromolecular structures were studied using an automated radiation sensitivity characterization procedure. The diffracted intensity variation with dose is described by a two-parameter model. This model includes a strong resolution-independent decay specific to room-temperature measurements along with a linear increase in overall Debye–Waller factors. An equivalent representation of sensitivity via a single parameter, normalized half-dose, is introduced. This parameter varies by an order of magnitude between the different structures studied. The data show a correlation of crystal radiation sensitivity with crystal solvent content but no dose-rate dependency was detected in the range 0.05–300 kGy s−1. The results of the crystal characterization are suitable for either optimal planning of room-temperature data collection or in situ crystallization plate screening experiments. PMID:23254652

  8. LLE (Laboratory for Laser Energetics) review

    SciTech Connect

    Kumpan, S.A.

    1990-01-01

    This volume of the LLE Review, covering the period April--June 1990, contains articles in two main sections, Progress in Laser Fusion and Advanced Technology Developments. The first article presents the theoretical interpretation of the glass-ablator cryogenic-implosion experiments recently conducted on OMEGA. It is followed by an article describing the analysis of neutron time-of-flight data taken during DT and DD experiments; and a discussion of the improvements to laser diagnostics that now provide for precise control of the OMEGA laser is given. This paper contains a report on the development of transparent conductive coatings for KDP crystals, and a discussion of the study of the transient-surface Debye-Waller effect in materials irradiated with an ultrafast laser.

  9. Vibron Solitons and Soliton-Induced Infrared Spectra of Crystalline Acetanilide

    NASA Astrophysics Data System (ADS)

    Takeno, S.

    1986-01-01

    Red-shifted infrared spectra at low temperatures of amide I (C=O stretching) vibrations of crystalline acetanilide measured by Careri et al. are shown to be due to vibron solitons, which are nonlinearity-induced localized modes of vibrons arising from their nonlinear interactions with optic-type phonons. A nonlinear eigenvalue equation giving the eigenfrequency of stationary solitons is solved approximately by introducing lattice Green's functions, and the obtained result is in good agreement with the experimental result. Inclusion of interactions with acoustic phonons yields the Debye-Waller factor in the zero-phonon line spectrum of vibron solitons, in a manner analogous to the case of impurity-induced localized harmonic phonon modes in alkali halides.

  10. Stochastic model for protein flexibility analysis

    NASA Astrophysics Data System (ADS)

    Xia, Kelin; Wei, Guo-Wei

    2013-12-01

    Protein flexibility is an intrinsic property and plays a fundamental role in protein functions. Computational analysis of protein flexibility is crucial to protein function prediction, macromolecular flexible docking, and rational drug design. Most current approaches for protein flexibility analysis are based on Hamiltonian mechanics. We introduce a stochastic model to study protein flexibility. The essential idea is to analyze the free induction decay of a perturbed protein structural probability, which satisfies the master equation. The transition probability matrix is constructed by using probability density estimators including monotonically decreasing radial basis functions. We show that the proposed stochastic model gives rise to some of the best predictions of Debye-Waller factors or B factors for three sets of protein data introduced in the literature.

  11. Molecular environment of Ni after its use for removal of CMP nanoparticle

    NASA Astrophysics Data System (ADS)

    Wei, Y.-L.; Chen, K.-W.; Peng, Y.-S.; Paul Wang, H.

    2010-07-01

    X-ray absorption spectroscopy (XAS) is employed to investigate the molecular environment around nickel that, in the form of nickel sulfate solution, has been added to precipitate nanoparticles in chemical mechanical polishing (CMP) waste water. After phase separation, for the liquid-phase sample, both the white line intensity in the normalized Ni K-edge X-ray absorption near edge structure (XANES) spectrum and the amplitude of the extended X-ray absorption fine structure (EXAFS) spectrum are enhanced due to the presence of solvation of water molecules, as compared to the solid-phase sample. Meanwhile, with the presence of water molecules, the coordination number increases; yet the Debye-Waller factor slightly decreases. The lack of chemical reduction of Ni 2+ in the CMP solution is suggested as the main reason why the charge neutralization precipitation method through the use of Ni 2+ is less effective than the system using Cu 2+ to precipitate nanoparticles as previously reported.

  12. Cross-cultural generalizability of personality dimensions: relating indigenous and imported dimensions in two cultures.

    PubMed

    Katigbak, M S; Church, A T; Akamine, T X

    1996-01-01

    The cross-cultural generalizability of personality dimensions was investigated by (a) identifying indigenous Philippine dimensions, (b) testing the cross-cultural replicability of the NEO 5-factor model (P. T. Costa & R.R. McCrae, 1992), and (c) relating Philippine and Western dimensions in Philippine and U.S. samples of college students. Filipino self-ratings (N = 536) on indigenous items were factor analyzed, and 6 Philippine dimensions were obtained. Conclusions about the replicability of the 5-factor model in the Philippines (N = 432) depended on whether exploratory, Procrustes, or confirmatory factor methods were used. In regression and joint factor analyses, moderate to strong associations were found between the Philippine dimensions and (a) dimensions from the 5-factor model in both Philippine (N = 387) and U.S. (N = 610) samples, and (b) the Tellegen model (A. Tellegen, 1985; A. Tellegen & N.G. Waller, in press) in a U.S. sample (N = 603). PMID:8558409

  13. Experimental signatures of a nonequilibrium phase transition governing the yielding of a soft glass

    NASA Astrophysics Data System (ADS)

    Hima Nagamanasa, K.; Gokhale, Shreyas; Sood, A. K.; Ganapathy, Rajesh

    2014-06-01

    We present direct experimental signatures of a nonequilibrium phase transition associated with the yield point of a prototypical soft solid—a binary colloidal glass. By simultaneously quantifying single-particle dynamics and bulk mechanical response, we identified the threshold for the onset of irreversibility with the yield strain. We extracted the relaxation time from the transient behavior of the loss modulus and found that it diverges in the vicinity of the yield strain. This critical slowing down is accompanied by a growing correlation length associated with the size of regions of high Debye-Waller factor, which are precursors to yield events in glasses. Our results affirm that the paradigm of nonequilibrium critical phenomena is instrumental in achieving a holistic understanding of yielding in soft solids.

  14. Xafs Studies of Transition Metal And Halogen Biomaterials in Invertebrate Tools

    SciTech Connect

    Tao, Y.; Shokes, J.E.; Scott, R.A.; Nesson, M.H.; Schofield, R.M.S.

    2009-06-04

    A significant fraction of arthropods, as well as some worms and members of other phyla, contain extraordinary amounts of transition metals (Mn, Fe, Cu, Zn) and halogens (Cl, Br, I) in their hardened tools (jaws, claws, fangs, stings, etc.). Bulk Zn EXAFS differs for different kinds of tools, whereas Br appears to occupy a common environment in different tools. Zn binding to histidine is observed for most samples but bulk Zn EXAFS is likely to sample a mixture of Zn coordination environments. Principal Component Analysis (PCA) suggests the presence of three main Zn coordination components. The similar Br EXAFS in widely different tools indicates that Br-phenyl is the dominant form, suggesting the presence of brominated aromatic amino acid-derived organic components in these biomaterials. Calculated Debye-Waller factors are used to simulate EXAFS when model compound data are unavailable.

  15. Non invasive measurement of strain and temperature by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Holden, T. M.; Root, J. H.; Tennant, D. C.; Kroeze, D. E.; Leggett, D.

    1990-06-01

    Two methods have been developed to determine temperature noninvasively within engineering components by neutron diffraction. The integrated intensity of a diffraction line depends on temperature through the Debye-Waller factor. The angular position of the line, in the absence of an applied load, depends on temperature through the thermal expansion coefficient. Temperature may thus be determined by accurate relative intensity measurements with respect to a reference temperature and, alternatively, by accurate measurement of the interplanar spacings. It was also shown to be feasible to measure the strain response to an applied load at elevated temperatures. Measurements were made on Waspalloy and the Ti alloy AMS 4928. For Waspalloy, the thermal expansion at zero stress gave the average temperature with a precision of +/- 4 K and agreed with thermocouple measurements to within 5 K on average. The intensity data suggest that temperature can be measured with a precision of +/- 10 K in a loaded component.

  16. Refinement of protein dynamic structure: normal mode refinement.

    PubMed Central

    Kidera, A; Go, N

    1990-01-01

    An x-ray crystallographic refinement method, referred to as the normal mode refinement, is proposed. The Debye-Waller factor is expanded in terms of the effective normal modes whose amplitudes and eigenvectors are experimentally determined by the crystallographic refinement. In contrast to the conventional method, the atomic motions are treated generally as anisotropic and concerted. This method is assessed by using the simulated x-ray data given by a Monte Carlo simulation of human lysozyme. In this article, we refine the dynamic structure by fixing the average static structure to exact coordinates. It is found that the normal mode refinement, using a smaller number of variables, gives a better R factor and more information on the dynamics (anisotropy and collectivity in the motion). Images PMID:2339115

  17. Aggregate sound velocities and acoustic Grüneisen parameter of iron up to 300 GPa and 1,200 K

    PubMed Central

    Dubrovinsky, L. S.; Dubrovinskaia, N. A.; Le Bihan, T.

    2001-01-01

    Successful interpretation of available geophysical data requires experimental and theoretical information on the elasticity of solids under physical conditions of Earth's interior. Because iron is considered as major component in Earth's core, elastic properties of iron at high pressures and temperatures are very important for modeling its composition and dynamics. We use in situ x-ray diffraction data on ɛ-iron at static pressures up to 300 GPa and temperatures to 1,200 K to determine the Debye–Waller temperature factors and calculate aggregate sound velocities and Grüneisen parameter of ɛ-iron by using an approach that is based on Rietveld refinement at high pressures and temperatures. PMID:11504937

  18. The origins of electrocardiography in Poland

    PubMed Central

    2015-01-01

    The progress of science and technology in the 19th century enabled better understanding of the electrical activity that occurs during a heartbeat. However, it was only the construction and introduction of the galvanometer that cleared the way for appropriate experimental and clinical studies. Marey, Waller, Wenckebach, Einthoven, and Pardee are just examples of the world's pioneers of electrocardiography. Polish researchers, including Cybulski, Eiger, Rzętkowski, Surzycki, and Latkowski, also contributed to the development of this area of study. The following article is a review aiming to reconstruct the origins of electrocardiography in Poland, both as a measurement method used in experiments and as a diagnostic tool in clinical studies conducted in the years preceding the outbreak of World War I. PMID:26336508

  19. Investigation on species distribution and EXAFS structure of aqueous rubidium pentaborate solutions

    NASA Astrophysics Data System (ADS)

    Miao, J. T.; Fang, C. H.; Fang, Y.; Zhu, F. Y.; Liu, H. Y.; Zhou, Y. Q.; Ge, H. W.; Sun, P. C.; Zhao, X. C.

    2016-04-01

    Based on the measured pH data and reported equilibrium constants, the main polyborate species formation existing in solution was investigated using the Newton iteration method at 298 and 333 K, and checked by the method of 11B nuclear magnetic resonance (NMR) spectroscopy. The neighboring structure of rubidium ion was studied at room temperature, which the structural parameters, including the coordination number, interatomic distance of Rb-O and Debye-Waller factor, were determined by the synchrotron radiation extended X-ray absorption fine structure (EXAFS). The results show that the average interatomic distance of Rb-O is 2.93 ± 0.004 Å and coordination number is 7.7 ± 0.9 in the first hydration shell around rubidium ion.

  20. Aqueous complexation of citrate with neodymium(III) and americium(III): a study by potentiometry, absorption spectrophotometry, microcalorimetry, and XAFS.

    PubMed

    Brown, M Alex; Kropf, A Jeremy; Paulenova, Alena; Gelis, Artem V

    2014-05-01

    The aqueous complexation of Nd(III) and Am(III) with anions of citrate was studied by potentiometry, absorption spectrophotometry, microcalorimetry, and X-ray absorption fine structure (XAFS). Using potentiometric titration data fitting the metal-ligand (L) complexes that were identified for Nd(III) were NdHL, NdL, NdHL2, and NdL2; a review of trivalent metal-citrate complexes is also included. Stability constants for these complexes were calculated from potentiometric and spectrophotometric titrations. Microcalorimetric results concluded that the entropy term of complex formation is much more dominant than the enthalpy. XAFS results showed a dependence in the Debye-Waller factor that indicated Nd(iii)-citrate complexation over the pH range of 1.56-6.12. PMID:24619154

  1. Vibrational dynamics and surface structure of Bi(111) from helium atom scattering measurements

    NASA Astrophysics Data System (ADS)

    Mayrhofer-Reinhartshuber, M.; Tamtögl, A.; Kraus, P.; Rieder, K. H.; Ernst, W. E.

    2012-03-01

    The Bi(111) surface was studied by elastic scattering of helium atoms at temperatures between 118 and 423 K. The observed diffraction patterns with clear peaks up to third order were used to model the surface corrugation using the eikonal approximation as well as the GR method. Best fit results were obtained with a rather large corrugation height compared to other surfaces with metallic character. The corrugation shows a slight enhancement of the surface electron density in between the positions of the surface atoms. The vibrational dynamics of Bi(111) were investigated by measurements of the Debye-Waller attenuation of the elastic diffraction peaks and a surface Debye temperature of (84 ± 8) K was determined. A decrease of the surface Debye temperature at higher temperatures that was recently observed on Bi nanofilms could not be confirmed in the case of our single-crystal measurements.

  2. Hydrologic data for urban studies in the Austin, Texas, metropolitan area, 1979

    USGS Publications Warehouse

    Slade, R.M.; Dorsey, M.E.; Gordon, J.D.; Mitchell, R.N.; Gaylord, J.L.

    1981-01-01

    This report contains rainfall and runoff data collected during the 1979 water year for the Austin, Texas, metropolitan area. In 1975, the program was expanded to include the collection of water-quality data. In 1978, the program was expanded to include a groundwater resources study of the south Austin metropolitan area in the Balcones fault zone. The information will be useful in determining the extent to which progressive urbanization will affect the yeild and mode of occurrence of storm runoff. The major streams in the study area are the Colorado River, Onion Creek, Barton Creek, Walnut Creek, Bull Creek, Boggy Creek, Shoal Creek, Williamson Creek, Slaughter Creek, Bear Creek, and Waller Creek. Detailed rainfall-runoff computations are presented for eight storm periods during the 1979 water year. Water-quality data for sites in the Austin metropolitan area are also given in this report. (USGS)

  3. Effects of Boron Addition to the Atomic Structure and Soft Magnetic Properties of FeCoB Films

    SciTech Connect

    Yang,A.; Imrane, H.; Lou, J.; Kirkland, J.; Vittoria, C.; Sun, N.; Harris, V.

    2008-01-01

    The magnetic, microwave, and the atomic structure properties of (Fe0.7Co0.3)1?xBx sputtered films on glass substrates were investigated. The addition of boron induced a decrease in coercivity and ferromagnetic resonance linewidth. The amorphous structure was formed at x ? 0.075. Extended x-ray absorption fine structure (EXAFS) of Fe and Co showed the reduced Fourier transform (FT) amplitude, and increased Debye-Waller factors as x was increased, indicating the increased disorder due to the thermal and structural displacements. Possible Fe-B bonding was observed with a reduced bond length, which indicates boron atoms' preference for staying in the interstitial sites in bcc unit cell.

  4. Fungible weights in logistic regression.

    PubMed

    Jones, Jeff A; Waller, Niels G

    2016-06-01

    In this article we develop methods for assessing parameter sensitivity in logistic regression models. To set the stage for this work, we first review Waller's (2008) equations for computing fungible weights in linear regression. Next, we describe 2 methods for computing fungible weights in logistic regression. To demonstrate the utility of these methods, we compute fungible logistic regression weights using data from the Centers for Disease Control and Prevention's (2010) Youth Risk Behavior Surveillance Survey, and we illustrate how these alternate weights can be used to evaluate parameter sensitivity. To make our work accessible to the research community, we provide R code (R Core Team, 2015) that will generate both kinds of fungible logistic regression weights. (PsycINFO Database Record PMID:26651981

  5. Local structure and superconductivity of the Ce1-xLaxRu2 Laves phase system

    NASA Astrophysics Data System (ADS)

    Saini, N. L.; Agrestini, S.; Amato, E.; Filippi, M.; di Castro, D.; Bianconi, A.; Manfrinetti, P.; Palenzona, A.; Marcelli, A.

    2004-09-01

    We have studied local structure of the Laves phase Ce1-xLaxRu2 superconductor by Ru K-edge extended x-ray absorption fine-structure measurements focusing on the small La concentration regime where the transition temperature Tc passes through a local maximum. We find that correlated Debye-Waller factor of the Ru-Ru bonds follows Tc with the varying La concentration in the system. Although, this remarkable Tc correlation on the local atomic structure suggests important role of the electron-lattice interactions, the band-structure effects seem more likely the reason to drive the anomalous superconducting behavior and the Tc maximum in this 4f system.

  6. Effects of boron addition to the atomic structure and soft magnetic properties of FeCoB films

    NASA Astrophysics Data System (ADS)

    Yang, Aria; Imrane, Hassan; Lou, Jing; Kirkland, Johnny; Vittoria, Carmine; Sun, Nian; Harris, Vincent G.

    2008-04-01

    The magnetic, microwave, and the atomic structure properties of (Fe0.7Co0.3)1-xBx sputtered films on glass substrates were investigated. The addition of boron induced a decrease in coercivity and ferromagnetic resonance linewidth. The amorphous structure was formed at x ˜0.075. Extended x-ray absorption fine structure (EXAFS) of Fe and Co showed the reduced Fourier transform (FT) amplitude, and increased Debye-Waller factors as x was increased, indicating the increased disorder due to the thermal and structural displacements. Possible Fe-B bonding was observed with a reduced bond length, which indicates boron atoms' preference for staying in the interstitial sites in bcc unit cell.

  7. LLE (Laboratory for Laser Energetics) review

    NASA Astrophysics Data System (ADS)

    Kumpan, S. A.

    This volume of the LLE Review, covering the period April to June 1990, contains articles in two main sections, Progress in Laser Fusion and Advanced Technology Developments. The first article presents the theoretical interpretation of the glass-ablator cryogenic-implosion experiments recently conducted on OMEGA. It is followed by an article describing the analysis of neutron time-of-flight data taken during DT and DD experiments; and a discussion of the improvements to laser diagnostics that now provide for precise control of the OMEGA laser is given. This paper contains a report on the development of transparent conductive coatings for KDP crystals, and a discussion of the study of the transient-surface Debye-Waller effect in materials irradiated with an ultrafast laser.

  8. Lattice Instability of 2H-TaSe2

    NASA Astrophysics Data System (ADS)

    John Bosco Balaguru, R.; Lawrence, N.; Alfred Cecil Raj, S.

    The charge density wave (CDW) in the layered compound 2H-TaSe2 at low temperatures has a commensurate phase, which causes super lattice points to appear in the Brillöuin zone of the undistorted phase. A Born-von Karman formalism has been employed for the calculation of phonon frequency distribution curves of 2H-TaSe2 both in the normal and in the commensurate charge density wave (CCDW) phases. A folding technique has been adopted for the calculation in the CCDW phase. The phonon distribution for both the phases have been reported. With these distributions the thermal properties such as specific heat capacity, Debye Waller factor W(k) and thermal conductivity have been worked out, and compared with the available experimental results.

  9. Molecular Dynamics of an α -helical Polypeptide: Temperature Dependence and Deviation from Harmonic Behavior

    NASA Astrophysics Data System (ADS)

    Levy, Ronald M.; Perahia, David; Karplus, Martin

    1982-02-01

    The mean square amplitudes of atomic fluctuations for a polypeptide (decaglycine) α -helix evaluated from molecular dynamics simulations at seven temperatures between 5 and 300 K are compared with analytic harmonic results and with experimental values. Above 100 K the harmonic approximation significantly underestimates the amplitudes of the displacements. Analysis of the time dependence of the fluctuations shows that low-frequency modes (<75 cm-1) dominate the atomic fluctuations and that there is a contribution with a very long relaxation time (>10ps). Quantum corrections to the amplitude of the fluctuations are found to be small above 50 K. The mean square amplitudes obtained from the molecular dynamics simulations are compared with the values derived from x-ray temperature (Debye-Waller) factors for metmyoglobin (80, 250, and 300 K) and ferrocytochrome c (300 K).

  10. Is co-ruminating with friends related to health problems in victimized adolescents?

    PubMed

    Guarneri-White, Maria E; Jensen-Campbell, Lauri A; Knack, Jennifer M

    2015-02-01

    Co-rumination, or the tendency to revisit and endlessly discuss problems and negative events, has been linked to depression and other emotional difficulties (Rose, Carson, & Waller, 2007). The current study examined the moderating effect of co-rumination on the relationship between peer victimization and depression, anxiety, PTSD symptoms, and health problems in 108 adolescents aged 10-15 years. Adolescents and a parent completed measures of adolescents' peer victimization, co-rumination, depression, and health problems. Results indicate that adolescents who are both peer victimized and engaged in high levels of co-rumination were at highest risk for psychological problems. Co-rumination also moderated the relationship between peer victimization and physical health problems via general depressive symptoms (i.e., moderated mediation). PMID:25544426

  11. Gastro-intestinal nematode infection in lambs — A model based on climatic indices for forecasting peak pasture larval contamination

    NASA Astrophysics Data System (ADS)

    Paton, G.

    1987-06-01

    The parasite Ostertagia circumcincta is the primary cause of parasitic gastro-enteritis in lambs during their first season at grass. The life-cycle of this nematode parasite involves the development and survival of the free-living stages on pasture. Accordingly the pasture is the site of deposition, development and transmission of infection and meteorological factors affecting the pasture will affect the parasites. In this paper two empirical models for forecasting the timing of the “summer wave” of infective larvae on pasture are presented. These models are similar in form to that described by Starr and Thomas (1980) but involve different approaches to assessing the temperature and moisture components of the daily index value. Further, using the prediction model described by Paton, Thomas and Waller (1984) as an investigative tool, certain tentative suggestions are made as to a general fundamental weakness of empirical index methods.

  12. Automated, ab initio calculations of X-ray spectra including many-body excitations and vibrational damping

    NASA Astrophysics Data System (ADS)

    Jorissen, Kevin; Story, Shauna; Rehr, John

    2014-03-01

    Accurate calculations of x-ray absorption spectra (XAS) often require linking several materials science codes. To reduce the complexity and support the hardware requirements of such calculations, we have virtualized XAS modeling workflows using a Cloud-based approach, with interfacing and configuration of codes handled by developers, and virtual HPC resources allocated on demand. When coupled to user-friendly GUIs this puts powerful multi-code simulations in the hands of general users. For instance, FEFF users can improve XAS interpretation and analysis using accurate ab initio Debye-Waller factors and self energy from the ABINIT DFT code, rather than semi-empirical models. Additionally, such workflows allow robust automation of large-scale calculation sets such as the Materials Project where our approach could enable a theoretical spectroscopy database of many thousands of structures for systematic study of materials. Supported by NSF-1216716.

  13. Establishment of an oil and gas database for increased recovery and characterization of oil and gas carbonate reservoir heterogeneity. [Jurassic Smackover Formation

    SciTech Connect

    Kopaska-Merkel, D.C.; Moore, H.E. Jr.; Mann, S.D.; Hall, D.R.

    1992-06-01

    This volume contains maps, well logging, structural cross section, graph of production history, porosity vs. natural log permeability plots, detailed core log, paragenetic sequence, and reservoir characterization sheet for the following fields in southwest Alabama: North Smiths Church oil field; North Wallers Creek oil field; Northeast Barnett oil field; Northwest Range oil field; Pace Creek oil field; Palmers Crossroads oil field; Perdido oil field; Puss Cuss Creek oil field; Red Creek gas condensate field; Robinson Creek oil field; Silas oil field; Sizemore Creek gas condensate field; Smiths Church gas condensate field; South Burnt Corn Creek oil field; South Cold Creek oil field; South Vocation oil field; South Wild Fork Creek gas condensate field; South Womack Hill oil field; Southeast Chatom gas condensate field; Southwest Barrytown oil field; and Souwilpa Creek gas condensate field.

  14. Establishment of an oil and gas database for increased recovery and characterization of oil and gas carbonate reservoir heterogeneity. Appendix 1, Volume 3

    SciTech Connect

    Kopaska-Merkel, D.C.; Moore, H.E. Jr.; Mann, S.D.; Hall, D.R.

    1992-06-01

    This volume contains maps, well logging, structural cross section, graph of production history, porosity vs. natural log permeability plots, detailed core log, paragenetic sequence, and reservoir characterization sheet for the following fields in southwest Alabama: North Smiths Church oil field; North Wallers Creek oil field; Northeast Barnett oil field; Northwest Range oil field; Pace Creek oil field; Palmers Crossroads oil field; Perdido oil field; Puss Cuss Creek oil field; Red Creek gas condensate field; Robinson Creek oil field; Silas oil field; Sizemore Creek gas condensate field; Smiths Church gas condensate field; South Burnt Corn Creek oil field; South Cold Creek oil field; South Vocation oil field; South Wild Fork Creek gas condensate field; South Womack Hill oil field; Southeast Chatom gas condensate field; Southwest Barrytown oil field; and Souwilpa Creek gas condensate field.

  15. Establishment of an oil and gas database for increased recovery and characterization of oil and gas carbonate reservoir heterogeneity. [Jurassic Smackover Formation

    SciTech Connect

    Kopasaka-Merkel, D.C.; Moore, H.E. Jr.; Mann, S.D; Hall, D.R.

    1992-06-01

    This volume contains maps, well log correlated to lithology, porosity and permeability, structural cross section, graph of production history, porosity vs. natural log permeability plots; detailed core log, porosity vs. natural permeability plot for one lithofacies, paragenetic sequence and reservoir characterization sheet for the following fields in southwest Alabama: Stave Creek oil field; Sugar Ridge oil field; Toxey oil field, Turkey Creed oil field; Turnerville oil field, Uriah oil field; Vocation oil field; Wallace oil field; Wallers Creek oil field; West Appleton oil field; West Barrytown oil field; West Bend oil field; West Okatuppa Creed oil field; Wild Fork Creek oil field; Wimberly oil field; Womack Hill oil field; and Zion Chapel oil field. (AT)

  16. Establishment of an oil and gas database for increased recovery and characterization of oil and gas carbonate reservoir heterogeneity. Appendix 1, Volume 4

    SciTech Connect

    Kopasaka-Merkel, D.C.; Moore, H.E. Jr.; Mann, S.D; Hall, D.R.

    1992-06-01

    This volume contains maps, well log correlated to lithology, porosity and permeability, structural cross section, graph of production history, porosity vs. natural log permeability plots; detailed core log, porosity vs. natural permeability plot for one lithofacies, paragenetic sequence and reservoir characterization sheet for the following fields in southwest Alabama: Stave Creek oil field; Sugar Ridge oil field; Toxey oil field, Turkey Creed oil field; Turnerville oil field, Uriah oil field; Vocation oil field; Wallace oil field; Wallers Creek oil field; West Appleton oil field; West Barrytown oil field; West Bend oil field; West Okatuppa Creed oil field; Wild Fork Creek oil field; Wimberly oil field; Womack Hill oil field; and Zion Chapel oil field. (AT)

  17. An accurate dynamical electron diffraction algorithm for reflection high-energy electron diffraction

    NASA Astrophysics Data System (ADS)

    Huang, J.; Cai, C. Y.; Lv, C. L.; Zhou, G. W.; Wang, Y. G.

    2015-12-01

    The conventional multislice method (CMS) method, one of the most popular dynamical electron diffraction calculation procedures in transmission electron microscopy, was introduced to calculate reflection high-energy electron diffraction (RHEED) as it is well adapted to deal with the deviations from the periodicity in the direction parallel to the surface. However, in the present work, we show that the CMS method is no longer sufficiently accurate for simulating RHEED with the accelerating voltage 3-100 kV because of the high-energy approximation. An accurate multislice (AMS) method can be an alternative for more accurate RHEED calculations with reasonable computing time. A detailed comparison of the numerical calculation of the AMS method and the CMS method is carried out with respect to different accelerating voltages, surface structure models, Debye-Waller factors and glancing angles.

  18. Equilibrium and structural studies on metal complexes of carbohyrates and their derivatives.

    PubMed

    Nagy, L; Szorcsik, A

    2002-04-10

    A summary is presented of the studies of our group on metal complexes of carbohydrates (aldoses, ketoses, mono-, di- and polysaccharides) and their derivatives (aldonic, alduronic acids, polyalcohols, amino sugars, amino acid sugar adducts, AMP, ATP, etc.). The results are reported of equilibrium, electrochemical, solution and solid-state structural studies of complexes of transition metals [Cu(II), Fe(III), Ni(II), Zn(II), Co(II), Ag(I), Mn in different oxidation states and organotin(IV)]. The structural parameters (coordination number, bond distance, and Debye-Waller factor) obtained by extended X-ray absorption fine structure spectroscopic (EXAFS) spectroscopy are discussed in detail. The general rules concerning the formation and structure of such complexes are emphasized. PMID:11931957

  19. Shear-deformation-potential constant of the conduction-band minima of Si: Pseudopotential calculations

    NASA Astrophysics Data System (ADS)

    Li, Ming-Fu; Gu, Zong-Quan; Wang, Jian-Qing

    1990-09-01

    We have calculated the value of the shear-deformation-potential constant Ξu of the conduction-band minima of Si and its temperature coefficient dΞu/dT. The value of Ξu is 9.0 eV for an ab initio pseudopotential calculation and 10.8 eV by the empirical-pseudopotential method (EPM), in good agreement with our experiment. The EPM calculations of the temperature dependence of Ξu yield the values of (dΞu/dT)||DW=-0.04 meV/K due to the Debye-Waller contribution, and (dΞu/dT)||TE=-0.04 meV/K for thermal expansion. We suspect and suggest that the existing experimental value of dΞu/dT~=+3 meV/K is unreliable due to large experimental uncertainty.

  20. Local environment of metal ions in phthalocyanines: K-edge X-ray absorption spectra.

    PubMed

    Rossi, G; d'Acapito, F; Amidani, L; Boscherini, F; Pedio, M

    2016-09-14

    We report a detailed study of the K-edge X-ray absorption spectra of four transition metal phthalocyanines (MPc, M = Fe, Co, Cu and Zn). We identify the important single and multiple scattering contributions to the spectra in the extended energy range and provide a robust treatment of thermal damping; thus, a generally applicable model for the interpretation of X-ray absorption fine structure spectra is proposed. Consistent variations of bond lengths and Debye Waller factors are found as a function of atomic number of the metal ion, indicating a variation of the metal-ligand bond strength which correlates with the spatial arrangement and occupation of molecular orbitals. We also provide an interpretation of the near edge spectral features in the framework of a full potential real space multiple scattering approach and provide a connection to the local electronic structure. PMID:27510989

  1. An in-situ heater for the XAS beamline (12-ID) in Australia

    NASA Astrophysics Data System (ADS)

    Johannessen, B.; Hussain, Z. S.; East, D. R.; Gibson, M. A.

    2013-04-01

    To accommodate for a growing number of requests by our user community an in-situ heater has been commissioned for the X-ray absorption spectroscopy (XAS) beamline 12-ID at the Australian Synchrotron. Here, we present an in-situ method for calibrating the temperature of the heating stage based on an anharmonic, correlated Einstein model. Specifically, we show that a temperature-dependant study of a bulk metallic foil (7.5 μm Cu) can be used to accurately calibrate the temperature of the heater. We also present the temperature-dependant coordination number, bond length, Debye-Waller factor, and third order cumulant to the bond length distribution function of the material from 18K to 1074K. At the higher temperatures we find that the atomic structure is comparable to that of an amorphous or liquid material indicating a gradual transition from crystalline to disordered atomic structure.

  2. Evidence of local structural order and spin-lattice coupling in the frustrated pyrochlore Y2Ru2O7

    NASA Astrophysics Data System (ADS)

    Castellano, C.; Berti, G.; Sanna, S.; Ruiz-Bustos, R.; van Duijn, J.; Brambilla, A.; Muñoz-Noval, Á.; Carretta, P.; Duò, L.; Demartin, F.

    2015-06-01

    We present an extended x-ray absorption fine structure study of the pyrochlore Y2Ru2O7 (8-298 K). We find evidence, on a local scale, of a significant magnetoelastic coupling at the Néel temperature TN˜77 K pointed out by a huge Debye-Waller σ2 factor deviation from a correlated temperature dependent Debye-like local order behavior plus a temperature independent static contribution. Moreover, we notice the occurrence of a potential local order-disorder structural phase transition at T*=150 K. This anomalous behavior is consistent with the pyrochlore's predisposition towards structural disorder and with a strong spin-phonon correlation. Remarkably the low-temperature order competes with the tendency of magnetic frustration to induce a less symmetric local structure.

  3. Diffraction studies of the thermal properties of nanocrystalline Pd and Cr

    SciTech Connect

    Eastman, J.A.; Thompson, L.J. ); Fitzsimmons, M.R.; Lawson, A.C.; Robinson, R.A. )

    1992-09-01

    Quantitative X-ray and neutron diffraction measurements were made on nanocrystalline and coarse-grained samples of Pd and Cr. For both materials, Debye-Waller parameter comparisons over a temperature range of approximately 20-300 K indicate that the nanocrystalline materials have increased static displacements of atoms from their equilibrium sites compared to coarse-grained material. No grain-size-correlated differences in thermal vibrational amplitude, lattice parameter, or thermal expansion coefficients were observed in either material. In contrast to earlier results on nanocrystalline Pd, significantly more non-peak intensity is observed from a nanocrystalline Cr sample than from a coarse-grained Cr sample. Impurities may account for the increased background intensity from nanocrystalline Cr. These results indicate that there is no significant grain boundary excess volume in nanocrystalline Pd, and therefore the reduced density typically observed in nanocrystalline Pd samples must be due to porosity.

  4. EXAFS and X-ray diffraction study of LaCoO3 across the spin-state transition

    NASA Astrophysics Data System (ADS)

    Sikolenko, V. V.; Troyanchuk, I. O.; Efimov, V. V.; Efimova, E. A.; Tiutiunnikov, S. I.; Karpinsky, D. V.; Pascarelli, S.; Zaharko, O.; Ignatov, A.; Aquilanti, D.; Selutin, A. G.; Shmakov, A. N.; Prabhakaran, D.

    2016-05-01

    A combined high-resolution Co K-edge extended x-ray absorption fine structure (EXAFS) and high-resolution X-ray powder diffraction (XRD) study has been performed to clarify the detail of anomalous behavior of temperature-dependent magnetic susceptibility curve on the LaCoO3 across the spin-state (∼120 K) transition. According to XRD analysis, the Debye-Waller factor of Co-O bond exhibit rapid growth below 20 K whereas the temperature dependence of the average Co-O bond length shows linear behavior from 10 K to 400 K. The EXAFS data show an anomalous decrease of the Co-O bond lengths with respect to those obtained by XRD. No local distortion of CoO6 octahedral as temperature increases up to 400 K has been detected.

  5. Electrically Detected Magnetic Resonance (EDMR) of Defects in GaN Light Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Ishida, H.; Maeda, H.; Hirano, A.; Kubozono, Y.; Furukawa, Y.

    1997-02-01

    Local structures around Pb(II) and Sn(II) in CH3NH3PbX3 (X = Cl, Br, I) and CH3NH3SnX3 (X = Br, I) were studied by Pb LIII-edge and Sn K-edge EXAFS in the temperature range of 10 to 293 K. The M-X distances (M = Pb, Sn; X = Cl, Br, I), the coordination numbers, and the Debye-Waller factors were determined in three, four, three, five, and two solid phases of CH3NH3PbCl3, CH3NH3PbBr3, CH3NH3PbI3, CH3NH3SnBr3, and CH3NH3SnI3, respectively. Five kinds of deformed octahedra consisting of halogens were observed.

  6. Influence of the chemical nature of implanted ions on the structure of a silicon layer damaged by implantation

    SciTech Connect

    Shcherbachev, K. D. Voronova, M. I.; Bublik, V. T.; Mordkovich, V. N. Pazhin, D. M.; Zinenko, V. I.; Agafonov, Yu. A.

    2013-12-15

    The influence of the implantation of silicon single crystals by fluorine, nitrogen, oxygen, and neon ions on the distribution of strain and the static Debye-Waller factor in the crystal lattice over the implanted-layer depth has been investigated by high-resolution X-ray diffraction. The density depth distribution in the surface layer of native oxide has been measured by X-ray reflectometry. Room-temperature implantation conditions have ensured the equality of the suggested ranges of ions of different masses and the energies transferred by them to the target. It is convincingly shown that the change in the structural parameters of the radiation-damaged silicon layer and the native oxide layer depend on the chemical activity of the implanted ions.

  7. Neutron diffraction studies of liquid iso-propanol

    NASA Astrophysics Data System (ADS)

    Zetterström, P.; Dahlborg, U.; Delaplane, R. G.; Howells, W. S.

    1991-07-01

    The structure of deuterated liquid iso-propanol has been studied with neutron diffraction at the LAD diffractometer at the ISIS spallation source. Measurements were performed at temperatures 190, 220, 250 and 275 K. To correct for inelastic effects a model for the dynamic structure factor which obeys detailed balance and included recoil effects was used. The static molecular structure factor SM(Q) exhibits a pre-peak at about 0.75 Å-1. The origin of the pre-peak, which increases in amplitude with temperature, is presently unknown. The structure of the iso-propanol molecule was obtained from the total pair distribution function and from a fit of the intramolecular form factor f1(Q) to the measured SM(Q) at large Q. The obtained values of the bond length and Debye-Waller factors are in good agreement to those obtained from lower alcohols.

  8. Coherent X-ray Scattering from Liquid-Air Interfaces

    NASA Astrophysics Data System (ADS)

    Shpyrko, Oleg

    Advances in synchrotron x-ray scattering techniques allow studies of structure and dynamics of liquid surfaces with unprecedented resolution. I will review x-ray scattering measurements of thermally excited capillary fluctuations in liquids, thin polymer liquid films and polymer surfaces in confined geometry. X-ray Diffuse scattering profile due to Debye-Waller like roughening of the surface allows to probe the distribution of capillary fluctuations over a wide range of length scales, while using X-ray Photon Correlation Spectroscopy (XPCS) one is able to directly couple to nanoscale dynamics of these surface fluctuations, over a wide range of temporal and spacial scales. I will also discuss recent XPCS measurements of lateral diffusion dynamics in Langmuir monolayers assembled at the liquid-air interface. This research was supported by NSF CAREER Grant 0956131.

  9. Intermediate range order dynamics - key to understanding of the glass transition

    NASA Astrophysics Data System (ADS)

    Russina, Margarita; Mezei, Ferenc

    2000-03-01

    Introducing a new experimental approach allowed us to extend the study of the collective dynamics to the length scale of intermediate range order in the model glass former Ca-K-NO 3 (CKN) using time-of-flight (NEAT/BENSC) and spin-echo (InLL/ILL) technique. Our results provide for the first time direct experimental evidence that the β-process is of relaxational nature and corresponds to fast heterogeneous flow of groups of atoms.We did not observe any sign of the sharp singularity of the effective Debye-Waller factor, which could be an indication of the mode coupling theory critical temperature (Gotze, Z. Phys. 60 (1985) 195; Gotze and Sjogren, Rep. Progr. Phys. 55 (1992) 242).

  10. Zinc cysteine active sites of metalloproteins: A density functional theory and x-ray absorption fine structure study

    NASA Astrophysics Data System (ADS)

    Dimakis, Nicholas; Farooqi, Mohammed Junaid; Garza, Emily Sofia; Bunker, Grant

    2008-03-01

    Density functional theory (DFT) and x-ray absorption fine structure (XAFS) spectroscopy are complementary tools for the biophysical study of active sites in metalloproteins. DFT is used to compute XAFS multiple scattering Debye Waller factors, which are then employed in genetic algorithm-based fitting process to obtain a global fit to the XAFS in the space of fitting parameters. Zn-Cys sites, which serve important functions as transcriptional switches in Zn finger proteins and matrix metalloproteinases, previously have proven intractable by this method; here these limitations are removed. In this work we evaluate optimal DFT nonlocal functionals and basis sets for determining optimal geometries and vibrational densities of states of mixed ligation Zn(His)4-n(Cys)n sites. Theoretical results are compared to experimental XAFS measurements and Raman spectra from the literature and tabulated for use.

  11. Sourcing and Communicating Cosmic Narratives -- A Role for the IAU?

    NASA Astrophysics Data System (ADS)

    Waller, William Howard

    2015-08-01

    Communicating astronomy critically depends on crafting competent and engaging stories. IAU Commission 55 has an opportunity to take the lead in exploring and celebrating astronomical narratives. Possibilities include an online "Astro Tales" publication of astronomical stories by IAU members for the general public (that complements the trade-oriented CAP), "Profiles in Astronomy" that feature interviews with IAU members, forums featuring exceptional science communicators and their cosmic stories, writing competitions for students, and an awards program. Through some version of these endeavors, the IAU could become a major arbiter of astronomical information and outreach worldwide. In this session, Dr. Waller will use his online journal "The Galactic Inquirer" at http://galacticinquirer.net as an exemplar and encourage input from participants.

  12. The influence of social anxiety on the body checking behaviors of female college students.

    PubMed

    White, Emily K; Warren, Cortney S

    2014-09-01

    Social anxiety and eating pathology frequently co-occur. However, there is limited research examining the relationship between anxiety and body checking, aside from one study in which social physique anxiety partially mediated the relationship between body checking cognitions and body checking behavior (Haase, Mountford, & Waller, 2007). In an independent sample of 567 college women, we tested the fit of Haase and colleagues' foundational model but did not find evidence of mediation. Thus we tested the fit of an expanded path model that included eating pathology and clinical impairment. In the best-fitting path model (CFI=.991; RMSEA=.083) eating pathology and social physique anxiety positively predicted body checking, and body checking positively predicted clinical impairment. Therefore, women who endorse social physique anxiety may be more likely to engage in body checking behaviors and experience impaired psychosocial functioning. PMID:25123084

  13. Dynamics and kinetics of monolayer CH4 on MgO(001) studied by helium-atom scattering

    NASA Astrophysics Data System (ADS)

    Jung, David R.; Cui, Jinhe; Frankl, Daniel R.

    1991-05-01

    The structure, vibrational excitations, and adsorption and desorption kinetics of monolayer CH4 on MgO have been investigated using several techniques of helium scattering. Structural information is presented in the form of high-order diffraction-peak intensities. A vibrational excitation of 7.5 meV measured by time-of-flight methods shows no dispersion. This excitation energy is used in an analysis of the Debye-Waller effect for the [00] and [1¯0] beams. Studies of adsorption and desorption rates exploiting the He-methane diffuse-scattering cross section indicate an island-growth mode and allow determination of the desorption activation energy. Differences between the low-coverage adsorption rates for adsorption on fresh versus previously exposed surfaces suggest that higher-binding-energy sites are present after the desorption of a methane monolayer.

  14. Psychopathic, not psychopath: taxometric evidence for the dimensional structure of psychopathy.

    PubMed

    Edens, John F; Marcus, David K; Lilienfeld, Scott O; Poythress, Norman G

    2006-02-01

    Although psychopathy is frequently regarded as qualitatively distinct from other conditions, relatively little research has examined whether psychopaths represent a distinct class of individuals. Using a sample of 876 prison inmates and court-ordered substance abuse patients who were administered the Psychopathy Checklist-Revised (R. D. Hare, 2003), the authors examined the latent structure of psychopathy using several taxometric procedures developed by Meehl and colleagues (P. E. Meehl & L. J. Yonce, 1994; N. G. Waller & P. E. Meehl, 1998). The results across these procedures offer no compelling support for the contention that psychopathy is a taxonic construct and contradict previous reports that psychopathy is underpinned by a latent taxon. The authors discuss the theoretical, public policy, and practice-level implications of these findings. PMID:16492104

  15. Moessbauer spectroscopic investigations of bimetallic FeCo, FeNi, and FeRu model catalysts supported on magnesium hydroxide carbonate

    SciTech Connect

    Nagorny, K.; Bubert, S.

    1987-11-01

    FeCo, FeNi, and FeRu alloys supported on basic magnesium carbonate have been prepared by precipitation from salt solutions at 340 K onto the support using ion exchange and have been subsequently annealed for 20 h under argon. The reduction, oxidation, and sintering behavior of the samples under H/sub 2/ or CO exposure has been investigated at 723 K by means of Moessbauer spectroscopy. The comparison of the resonance absorption areas of the spectra taken at 4 and 295 K allowed the calculation of the Debye temperatures and Debye-Waller factors of the different components. From the Debye-Waller factors the relative fractions could be extrapolated to the conditions at 0 K. The kinetics of the H/sub 2/ exposure showed an increase in the reduction velocity as well as in the degree of reduction in the sequence FeCo < FeNi < FeRu. Above a critical particle diameter a phase separation occurred because of the segregation of an iron-rich phase at the surface of the alloy particles. The kinetics of the CO exposure demonstrated that with FeCo clusters iron(III) surface oxide layers form, whereas with FeNi clusters iron(II) surface oxide layers are generated. FeCo clusters with a cobalt content of 25% form only unstable surface carbides, whereas clusters with a cobalt content of about 5% form stable bulk carbides. The velocity of carbide formation increases with decreasing particle size. Based on the present data a model is proposed which explains the behavior of FeMe/magnesium hydroxide carbonates catalysts in H/sub 2/ and CO atmospheres.

  16. Probing interlayer interactions between graphene and metal substrates by supersonic rare-gas atom scattering

    NASA Astrophysics Data System (ADS)

    Shichibe, H.; Satake, Y.; Watanabe, K.; Kinjyo, A.; Kunihara, A.; Yamada, Y.; Sasaki, M.; Hayes, W. W.; Manson, J. R.

    2015-04-01

    We demonstrate that highly surface-sensitive supersonic rare-gas (He, Ar, and Xe) atom scattering, in both the quantum and classical regimes, can probe and quantify the interlayer interactions between graphene monolayers and metal substrates in terms of the Debye temperature corresponding to the surface normal vibration, and the surface effective mass. As models of the strongly and weakly interacting graphene, we investigated two systems, graphene on Ru(0001) and Pt(111), respectively. The experimental data for Ar and Xe are compared with the results from theoretical simulations based on the classical smooth surface model. For gr/Pt(111) we find that the scattering pattern of the rare-gas beam, including the Debye-Waller attenuation of the He beam, are quite similar to that from highly oriented pyrolytic graphite (HOPG); this suggests that the graphene-Pt(111) interaction is much like a van der Waals interaction. On the contrary, for the gr/Ru(0001) system, we find a smaller Debye-Waller attenuation and a larger surface effective mass, indicating that graphene on Ru(0001) is tightly bonded to the substrate. Furthermore, asymmetrical spectral shapes in the Ar and Xe scattering spectra from gr/Ru(0001) are interpreted as a result of the lateral distribution of the interlayer interaction corresponding to the moiré pattern. It is found that the "valley" region of the moiré pattern has high effective mass reflecting stronger bonding to the substrate, contributing to the high reflectivity of the He beam reported for this system. On the other hand, the effective mass of the "hill" region is found to be similar to that of HOPG, indicating that this region is well decoupled from the substrate. These results demonstrate a unique capability of atom scattering to probe and evaluate the molecule-substrate interaction and its spatial distributions.

  17. [Prediction of short loops in the proteins with internal disorder].

    PubMed

    Deriusheva, E I; Galzitskaia, O V; Serdiuk, I N

    2008-01-01

    New possibility of the FoldUnfold program for prediction of short disordered regions (loops), which appears by using the short window width (3 amino acid residues), was described. For three representatives of the proteins G family the FoldUnfold program predicted almost all short loops and yield results are well compatible with the X-ray structure data. We have classified the loops predicted in the protein Ras-p21 structure in two types. In the first type, loops have high values of the Debye-Waller factor typical of the so-called functional loops (flexible loops). In the other type, loops have lower values of the Debye-Waller factor and can be considered as loops connecting secondary structure elements (rigid loops). When the results of prediction with the use of our program are compared with the results of other programs (PONDR, RONN, DisEMBL, PreLINK, IUPred, GlobPlot 2, FoldIndex), it is seen that the first enables far better prediction of short loop positions. Use of FoldUnfold for ubiquitin-like domain h-PLIC-2 allows to resolve such task as definition of boundary between the structured and unstructured regions in proteins with a big portion of disordered regions. The FoldUnfold program defines a clear boundary between the structured and unstructured regions at amino acid residues 30-31,whereas each of the other programs outlines the boundary from the 28-th amino acid residues through the 70th. PMID:19140328

  18. EXAFS and XANES investigation of (Li, Ni) codoped ZnO thin films grown by pulsed laser deposition.

    PubMed

    Mino, Lorenzo; Gianolio, Diego; Bardelli, Fabrizio; Prestipino, Carmelo; Senthil Kumar, E; Bellarmine, F; Ramanjaneyulu, M; Lamberti, Carlo; Ramachandra Rao, M S

    2013-09-25

    Ni doped, Li doped and (Li, Ni) codoped ZnO thin films were successfully grown using a pulsed laser deposition technique. Undoped and doped ZnO thin films were investigated using extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge spectroscopy (XANES). Preliminary investigations on the Zn K-edge of the undoped and doped ZnO thin films revealed that doping has not influenced the average Zn-Zn bond length and Debye-Waller factor. This shows that both Ni and Li doping do not appreciably affect the average local environment of Zn. All the doped ZnO thin films exhibited more than 50% of substitutional Ni, with a maximum of 77% for 2% Ni and 2% Li doped ZnO thin film. The contribution of Ni metal to the EXAFS signal clearly reveals the presence of Ni clusters. The Ni-Ni distance in the Ni(0) nanoclusters, which are formed in the film, is shorter with respect to the reference Ni metal foil and the Debye-Waller factor is higher. Both facts perfectly reflect what is expected for metal nanoparticles. At the highest doping concentration (5%), the presence of Li favors the growth of a secondary NiO phase. Indeed, 2% Ni and 5% Li doped ZnO thin film shows %Nisub = 75 ± 11, %Nimet = 10 ± 8, %NiO = 15 ± 8. XANES studies further confirm that the substitutional Ni is more than 50% in all the samples. These results explain the observed magnetic properties. PMID:23988792

  19. The effect of the exchange-correlation functional on H{sub 2} dissociation on Ru(0001)

    SciTech Connect

    Wijzenbroek, M.; Kroes, G. J.

    2014-02-28

    The specific reaction parameter (SRP) approach to density functional theory (DFT) has enabled a chemically accurate description of reactive scattering experiments for activated H{sub 2}–metal systems (H{sub 2} + Cu(111) and Cu(100)), but its application has not yet resulted in a similarly accurate description of non-activated or weakly activated H{sub 2}-metal systems. In this study, the effect of the choice of the exchange-correlation functional in DFT on the potential energy surface and dynamics of H{sub 2} dissociation on Ru(0001), a weakly activated system, is investigated. In total, full potential energy surfaces were calculated for over 20 different functionals. The functionals investigated include functionals incorporating an approximate description of the van der Waals dispersion in the correlation functional (vdW-DF and vdW-DF2 functionals), as well as the revTPSS meta-GGA. With two of the functionals investigated here, which include vdW-DF and vdW-DF2 correlation, it has been possible to accurately reproduce molecular beam experiments on sticking of H{sub 2} and D{sub 2}, as these functionals yield a reaction probability curve with an appropriate energy width. Diffraction probabilities computed with these two functionals are however too high compared to experimental diffraction probabilities, which are extrapolated from surface temperatures (T{sub s}) ⩾ 500 K to 0 K using a Debye–Waller model. Further research is needed to establish whether this constitutes a failure of the two candidate SRP functionals or a failure of the Debye–Waller model, the use of which can perhaps in future be avoided by performing calculations that include the effect of surface atom displacement or motion, and thereby of the experimental T{sub s}.

  20. Tracking changes in natural organic carbon character during artificial infiltration using flourescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Köhler, Stephan J.; Lavonen, Elin; McCleaf, Philip; Hummel, Angelica; Berggren Kleja, Dan; Johansson, Per-Olof

    2016-04-01

    In many Nordic countries more than half of the drinking water is produced using surface water. Artificial infiltration allows increasing water withdrawal from groundwater but may not be sustainable during longer periods. Here we report results from a one year study on changes in dissolved organic carbon concentration (DOC) and DOC character along the whole infiltration area starting with the stream water until the drinking water plant raw water intake. Both DOC, fluorescence spectroscopy and LC-OCD are used to understand the observed changes in the aquatic phase. Large seasonal changes close to the infiltration basin contrasts with stable conditions further away. Selective removal of terrestrial type of DOC is coherent using both analytical techniques. A simple empirical relationship between Humic like material and absorbance developed elsewhere also holds in this system (Köhler et al 2016). Fluorescence is a fast and promising tool for tracking changes in natural organic carbon character during artificial infiltration. References Stephan J. Köhler, Elin Lavonen, Alexander Keucken, Philippe Schmitt-Kopplin, Tom Spanjer and Kenneth Persson. Upgrading coagulation with hollow-fibre nanofiltration for improved organic matter removal during surface water treatment Water research (2016) 89:232-240.

  1. HESS Opinions "On forecast (in)consistency in a hydro-meteorological chain: curse or blessing?"

    NASA Astrophysics Data System (ADS)

    Pappenberger, F.; Cloke, H. L.; Persson, A.; Demeritt, D.

    2011-01-01

    Flood forecasting increasingly relies on Numerical Weather Prediction (NWP) forecasts to achieve longer lead times (see Cloke et al., 2009; Cloke and Pappenberger, 2009). One of the key difficulties that is emerging in constructing a decision framework for these flood forecasts is when consecutive forecasts are different, leading to different conclusions regarding the issuing of forecasts, and hence inconsistent. In this opinion paper we explore some of the issues surrounding such forecast inconsistency (also known as "jumpiness", "turning points", "continuity" or number of "swings"; Zoster et al., 2009; Mills and Pepper, 1999; Lashley et al., 2008). We begin by defining what forecast inconsistency is; why forecasts might be inconsistent; how we should analyse it; what we should do about it; how we should communicate it and whether it is a totally undesirable property. The property of consistency is increasingly emerging as a hot topic in many forecasting environments (for a limited discussion on NWP inconsistency see Persson, 2011). However, in this opinion paper we restrict the discussion to a hydro-meteorological forecasting chain in which river discharge forecasts are produced using inputs from NWP. In this area of research (in)consistency is receiving recent interest and application (see e.g., Bartholmes et al., 2008; Pappenberger et al., 2011).

  2. Extremely red objects in the fields of high redshift radio galaxies

    NASA Technical Reports Server (NTRS)

    Persson, S. E.; Mccarthy, P. J.; Dressler, Alan; Matthews, Keith

    1993-01-01

    We are engaged in a program of infrared imaging photometry of high redshift radio galaxies. The observations are being done using NICMOS2 and NICMOS3 arrays on the DuPont 100-inch telescope at Las Campanas Observatory. In addition, Persson and Matthews are measuring the spectral energy distributions of normal cluster galaxies in the redshift range 0 to 1. These measurements are being done with a 58 x 62 InSb array on the Palomar 5-m telescope. During the course of these observations we have imaged roughly 20 square arcminutes of sky to limiting magnitudes greater than 20 in the J, H, and K passbands (3 sigma in 3 square arcseconds). We have detected several relatively bright, extremely red, extended objects during the course of this work. Because the radio galaxy program requires Thuan-Gunn gri photometry, we are able to construct rough photometric energy distributions for many of the objects. A sample of the galaxy magnitudes within 4 arcseconds diameter is given. All the detections are real; either the objects show up at several wavelengths, or in subsets of the data. The reddest object in the table, 9ab'B' was found in a field of galaxies in a rich cluster at z = 0.4; 9ab'A' lies 8 arcseconds from it.

  3. Surface-state Mediated Interactions: Analytic and Numerical Results for 3 Adatoms

    NASA Astrophysics Data System (ADS)

    Hyldgaard, Per; Einstein, T. L.

    2002-03-01

    When mediated by an isotropic Shockley surface-state band (e.g. on noble-metal (111) surfaces), indirect oscillatory electronic interactions between adsorbed atoms(TLE, in Handbook of Surf. Sci.) 1, ed. W. N. Unertl (Elsevier, 1996). are both strong and (in contrast to bulk-mediated interactions) slowly decaying with separation. Moreover, their simple analytical form(P. Hyldgaard and M. Persson, J. Phys.: Cond. Matt. 12), L13 (2000). has been observed experimentally.(J. Repp et al., PRL 85), 2981 (2000); K. Knorr et al., preprint. The s-wave phase shift needed for analysis is obtained from STM images of standing-wave patterns. The interaction of three adsorbed atoms is the sum of the 3 such pair energies plus a trio contribution from electrons traversing the perimeter, d, of the three-adatom cluster.^2,(T. L. Einstein, Surf. Sci. 84), L497 (1979). This trio contribution has a slightly weaker amplitude than the pair energy and a slightly faster asymptotic envelope decay, d-5/2. It also has a different but well-defined d-dependent oscillation period. The asymptotic description is compared with exact model calculations. It should be observable experimentally. http://www2.physics.umd.edu/ einstein/

  4. Determining the Locations of Brown Dwarfs in Young Star Clusters

    NASA Technical Reports Server (NTRS)

    Porter, Lauren A.

    2005-01-01

    Brown dwarfs are stellar objects with masses less than 0.08 times that of the Sun that are unable to sustain nuclear fusion. Because of the lack of fusion, they are relatively cold, allowing the formation of methane and water molecules in their atmospheres. Brown dwarfs can be detected by examining stars' absorption spectra in the near-infrared to see whether methane and water are present. The objective of this research is to determine the locations of brown dwarfs in Rho Ophiuchus, a star cluster that is only 1 million years old. The cluster was observed in four filters in the near-infrared range using the Wide-Field Infra-Red Camera (WIRC) on the 100" DuPont Telescope and Persson's Auxiliary Nasymith Infrared Camera (PANIC) on the 6.5-m Magellan Telescope. By comparing the magnitude of a star in each of the four filters, an absorption spectrum can be formed. This project uses standard astronomical techniques to reduce raw frames into final images and perform photometry on them to obtain publishable data. Once this is done, it will be possible to determine the locations and magnitudes of brown dwarfs within the cluster.

  5. The Mid-Infrared Cepheid Distance Scale: A Reconnaissance Program of Cepheids in the Local Group

    NASA Astrophysics Data System (ADS)

    Madore, Barry; Freedman, Wendy; Mager, Violet; Rigby, Jane

    2008-03-01

    We request archival funding to search for serendipitous IRAC detections of known Cepheids in Local Group galaxies. This archival proposal is a parallel study in support of a Cycle 5 GO proposal (PI: Freedman) to re-calibrate the Cepheid distance scale from the ground up using new IRAC photometry of ten Galactic Cepheids having HST trigonometric parallaxes (Benedict et al. 2007), in combination with eighty LMC Cepheids (from Persson et al. 2004), to establish the slope and secure the zero point of the Cepheid Period-Luminosity Relation at 3.6 and 4.5 micron. Here we intend to characterize the mid-infrared detectability of Cepheids in Local Group galaxies, by examining upwards of 8,000 archival images containing cataloged Cepheids with known periods and predicted luminosities. The Cepheids in these images exhibit a wide range of background intensity, often have complex crowding, and have a wide range of apparent magnitudes. From this reconnaissance survey we will be able to directly assess the ability of Spitzer to obtain high signal-to-noise observations of Cepheids in individual Local Group galaxies, and we will select the least crowded and least confused of the serendipitously--obserserved Cepheids. We plan to target this sample in the Warm Mission, with the goal of putting the Local Group securely onto the mid-infrared Cepheid distance scale.

  6. Elucidating the contact mechanics of aluminum silicon surfaces with Green's function molecular dynamics

    NASA Astrophysics Data System (ADS)

    Campañá, Carlos; Müser, Martin H.; Denniston, Colin; Qi, Yue; Perry, Thomas A.

    2007-12-01

    We study the contact mechanics of a flat, elastic wall pressed against a rigid substrate with Green's function molecular dynamics. The substrate's height profiles are parametrized from atomic force microscope topography measurements of two different aluminum-silicon alloys. In both samples, roughness lives on disparate length scales, i.e., on relatively large scales defined by size and mean separation of load-bearing silicon particles and on much smaller scales associated with the roughness on top of individual particles. The major differences between the two alloys are their silicon content and the typical silicon particle geometry. These differences lead to quite different stress distributions on both mesoscale and microscale in our calculations. A common feature is that the stress distribution decays exponentially for large stresses σ and not like a Gaussian. Persson's contact mechanics theory is generalized to the case where contact can only occur on silicon particles. This generalization predicts relatively accurate microscopic mean square stresses, however, it fails to predict accurate numbers for mean square stresses on the mesoscopic scales. Local overlap models are not accurate either, because they fail to describe the contact morphology.

  7. ADENOVIRUS INTERACTION WITH ITS CELLULAR RECEPTOR CAR.

    SciTech Connect

    HOWITT,J.; ANDERSON,C.W.; FREIMUTH,P.

    2001-08-01

    The mechanism of adenovirus attachment to the host cell plasma membrane has been revealed in detail by research over the past 10 years. It has long been known that receptor binding activity is associated with the viral fibers, trimeric spike proteins that protrude radially from the vertices of the icosahedral capsid (Philipson et al. 1968). In some adenovirus serotypes, fiber and other virus structural proteins are synthesized in excess and accumulate in the cell nucleus during late stages of infection. Fiber protein can be readily purified from lysates of cells infected with subgroup C viruses, for example Ad2 and Ad5 (Boulanger and Puvion 1973). Addition of purified fiber protein to virus suspensions during adsorption strongly inhibits infection, indicating that fiber and intact virus particles compete for binding sites on host cells (Philipson et al. 1968; Hautala et al. 1998). Cell binding studies using purified radiolabeled fiber demonstrated that fiber binds specifically and with high affinity to the cell plasma membrane, and that cell lines typically used for laboratory propagation of adenovirus have approximately 10{sup 4} high-affinity receptor sites per cell (Persson et al. 1985; Freimuth 1996). Similar numbers of high-affinity binding sites for radiolabeled intact virus particles also were observed (Seth et al. 1994).

  8. New insights on the Karoo shale gas potential from borehole KZF-1 (Western Cape, South Africa)

    NASA Astrophysics Data System (ADS)

    Campbell, Stuart A.; Götz, Annette E.; Montenari, Michael

    2016-04-01

    A study on world shale reserves conducted by the Energy Information Agency (EIA) in 2013 concluded that there could be as much as 390 Tcf recoverable reserves of shale gas in the southern and south-western parts of the Karoo Basin. This would make it the 8th-largest shale gas resource in the world. However, the true extent and commercial viability is still unknown, due to the lack of exploration drilling and modern 3D seismic. Within the framework of the Karoo Research Initiative (KARIN), two deep boreholes were drilled in the Eastern and Western Cape provinces of South Africa. Here we report on new core material from borehole KZF-1 (Western Cape) which intersected the Permian black shales of the Ecca Group, the Whitehill Formation being the main target formation for future shale gas production. To determine the original source potential for shale gas we investigated the sedimentary environments in which the potential source rocks formed, addressing the research question of how much sedimentary organic matter the shales contained when they originally formed. Palynofacies indicates marginal marine conditions of a stratified basin setting with low marine phytoplankton percentages (acritarchs, prasinophytes), good AOM preservation, high terrestrial input, and a high spores:bisaccates ratio (kerogen type III). Stratigraphically, a deepening-upward trend is observed. Laterally, the basin configuration seems to be much more complex than previously assumed. Furthermore, palynological data confirms the correlation of marine black shales of the Prince Albert and Whitehill formations in the southern and south-western parts of the Karoo Basin with the terrestrial coals of the Vryheid Formation in the north-eastern part of the basin. TOC values (1-6%) classify the Karoo black shales as promising shale gas resources, especially with regard to the high thermal maturity (Ro >3). The recently drilled deep boreholes in the southern and south-western Karoo Basin, the first since the

  9. Seine estuary modelling and AirSWOT measurements validation

    NASA Astrophysics Data System (ADS)

    Chevalier, Laetitia; Lyard, Florent; Laignel, Benoit

    2013-04-01

    In the context of global climate change, knowing water fluxes and storage, from the global scale to the local scale, is a crucial issue. The future satellite SWOT (Surface Water and Ocean Topography) mission, dedicated to the surface water observation, is proposed to meet this challenge. SWOT main payload will be a Ka-band Radar Interferometer (KaRIn). To validate this new kind of measurements, preparatory airborne campaigns (called AirSWOT) are currently being designed. AirSWOT will carry an interferometer similar to Karin: Kaspar-Ka-band SWOT Phenomenology Airborne Radar. Some campaigns are planned in France in 2014. During these campaigns, the plane will fly over the Seine River basin, especially to observe its estuary, the upstream river main channel (to quantify river-aquifer exchange) and some wetlands. The present work objective is to validate the ability of AirSWOT and SWOT, using a Seine estuary hydrodynamic modelling. In this context, field measurements will be collected by different teams such as GIP (Public Interest Group) Seine Aval, the GPMR (Rouen Seaport), SHOM (Hydrographic and Oceanographic Service of the Navy), the IFREMER (French Research Institute for Sea Exploitation), Mercator-Ocean, LEGOS (Laboratory of Space Study in Geophysics and Oceanography), ADES (Data Access Groundwater) ... . These datasets will be used first to validate locally AirSWOT measurements, and then to improve a hydrodynamic simulations (using tidal boundary conditions, river and groundwater inflows ...) for AirSWOT data 2D validation. This modelling will also be used to estimate the benefit of the future SWOT mission for mid-latitude river hydrology. To do this modelling,the TUGOm barotropic model (Toulouse Unstructured Grid Ocean model 2D) is used. Preliminary simulations have been performed by first modelling and then combining to different regions: first the Seine River and its estuarine area and secondly the English Channel. These two simulations h are currently being

  10. Spectro-dynamical asteroid families in the main belt

    NASA Astrophysics Data System (ADS)

    Bus, S.

    2014-07-01

    Spectral observations of collisionally-derived asteroid families continue to provide strong evidence that the surfaces of members from each family are spectrally homogeneous. This apparent homogeneity provides motivation to use new approaches in combining physical observations, such as spectral colors or albedo, with orbital parameters for the identification of family members and interlopers (e.g. [1,2]). The work described here uses the combined Sloan Digital Sky Survey colors (fourth release of the SDSS Moving Object Catalog [3]) and proper orbital elements from the Asteroids-Dynamics Site (AstDyS [4]) for 39,147 asteroids with semimajor axes between 2.1 and 3.2 au to search for ''spectro-dynamical'' families. The analysis is designed to identify groupings of asteroids that form statistically significant peaks in number density compared to the background population for a fixed spectral color distribution. A number of techniques from multivariate analysis are folded together and have been calibrated to accommodate asteroid families of different size, shape, and number density. In the final phase of the analysis, the number density for asteroids within a given spectral range is represented by 2-dimensional contour slices through proper-element space, and a visual inspection is made to confirm the reality of each grouping. Some families show evidence of complex structure that may be indicative of multiple collisional events over the history of the family. An example of this is the Karin family, which is located within the older, much larger Koronis family [5]. While both families are composed of asteroids classified as S-types, there is a significant color difference between the Koronis and Karin asteroids that is used to distinguish between members of the two families. In the same way, the Vesta family appears to be comprised of two distributions of asteroids that are offset in proper-element space and exhibit a statistically significant difference in the shape of

  11. Willem Einthoven and the birth of clinical electrocardiography a hundred years ago.

    PubMed

    Barold, S Serge

    2003-01-01

    The first electrocardiogram (ECG) from the intact human heart was recorded with a mercury capillary electrometer by Augustus Waller in May 1887 at St. Mary's Hospital, London. The tracings were poor and exhibited only 2 distorted deflections. Willem Einthoven (1860-1927) who was professor of physiology at the University of Leiden, The Netherlands, began his studies of the ECG with the mercury capillary electrometer, and improved its distortion mathematically so that he was finally able to register a good representation of the ECG before the beginning of the twentieth century. He later further improved ECG recordings with the introduction of a string galvanometer of his design. Einthoven published his first article about the string galvanometer in 1901, followed by a more detailed description in 1903 which included a report of ECGs taken with the new instrument. The year 2002 marks the centennial of Willem Einthoven's first recording of the ECG in a clinically applicable fashion with the string galvanometer. The clinical use of Einthoven's immobile equipment required transtelephonic transmission of the ECG from the physiology laboratory to the clinic at the Academic Hospital about a mile away as documented in the 1906 paper on the "télécardiogramme". This report contained a wealth of ECG patterns and arrhythmias. Einthoven developed a system of electrocardiographic standardization that continues to be used all over the world and introduced the triaxial bipolar system with 3 limb leads and thus established uniformity of the recording process. Einthoven also conceived the famous equilateral triangle with leads I, II, and III at its sides and the calculation of the electrical axis (in the frontal plane) depicted as a single vector with an arrow at the center of the triangle. Einthoven recognized the great potential importance of the ECG as a diagnostic and investigative tool and his achievements made him the founder of modern electrocardiography. He was awarded the

  12. Cross linking molecular systems to form ultrathin dielectric layers

    NASA Astrophysics Data System (ADS)

    Feng, Danqin

    Dehydrogenation leads to cross linking of polymer or polymer like formation in very different systems: self-assembled monolayers and in closo -carboranes leading to the formation of semiconducting and dielectric boron carbide. We find evidence of intermolecular interactions for a self-assembled monolayer (SAM) formed from a large molecular adsorbate, [1,1';4',1"-terphenyl]-4,4"-dimethanethiol, from the dispersion of the molecular orbitals with changing the wave vector k and from the changes with temperature. With the formation self assembled molecular (SAM) layer, the molecular orbitals hybridize to electronic bands, with indications of significant band dispersion of the unoccupied molecular orbitals. Although organic adsorbates and thin films are generally regarded as "soft" materials, the effective Debye temperature, indicative of the dynamic motion of the lattice normal to the surface, can be very high, e.g. in the multilayer film formed from [1,1'-biphenyl]-4,4'-dimethanethiol (BPDMT). Depending on molecular orientation, the effective Debye temperature can be comparable to that of graphite due to the 'stiffness' of the benzene rings, but follows the expected Debye-Waller behavior for the core level photoemission intensities with temperature. This is not always the case. We find that a monomolecular film formed from [1,1';4',1"-terphenyl]-4,4"-dimethanethiol deviates from Debye-Waller temperature behavior and is likely caused by temperature dependent changes in molecular orientation. We also find evidence for the increase in dielectric character with polymerization (cross-linking) in spite of the decrease in the HOMO-LUMO gap upon irradiation of TPDMT. The changes in the HOMO-LUMO gap, with cross-linking, are roughly consistent with the band dispersion. The decomposition and cross-linking processes are also accompanied by changes in molecular orientation. The energetics of the three isomeric carborane cage compounds [ closo-1,2-orthocarborane, closo-1

  13. Water uptake by a maize root system - An explicit numerical 3-dimensional simulation.

    NASA Astrophysics Data System (ADS)

    Leitner, Daniel; Schnepf, Andrea; Klepsch, Sabine; Roose, Tiina

    2010-05-01

    Water is one of the most important resources for plant growth and function. An accurate modelling of the unsaturated flow is not only substantial to predict water uptake but also important to describe nutrient movement regarding water saturation and transport. In this work we present a model for water uptake. The model includes the simultaneous flow of water inside the soil and inside the root network. Water saturation in the soil volume is described by the Richards equation. Water flow inside the roots' xylem is calculated using the Poiseuille law for water flow in a cylindrical tube. The water saturation in the soil as well as water uptake of the root system is calculated numerically in three dimensions. We study water uptake of a maize plant in a confined pot under different supply scenarios. The main improvement of our approach is that the root surfaces act as spatial boundaries of the soil volume. Therefore water influx into the root is described by a surface flux instead of a volume flux, which is commonly given by an effective sink term. For the numerical computation we use the following software: The 3-dimensional maize root architecture is created by a root growth model based on L-Systems (Leitner et al 2009). A mesh of the surrounding soil volume is created using the meshing software DistMesh (Persson & Strang 2004). Using this mesh the partial differential equations are solved with the finite element method using Comsol Multiphysics 3.5a. Modelling results are related to accepted water uptake models from literature (Clausnitzer & Hopmans 1994, Roose & Fowler 2004, Javaux et al 2007). This new approach has several advantages. By considering the individual roots it is possible to analyse the influence of overlapping depletion zones due to inter root competition. Furthermore, such simulations can be used to estimate the influence of simplifying assumptions that are made in the development of effective models. The model can be easily combined with a nutrient

  14. Assessment of wear and periacetabular osteolysis using dual energy computed tomography on a pig cadaver to identify the lowest acceptable radiation dose

    PubMed Central

    Skorpil, M.; Nowik, P.; Olivecrona, H.; Crafoord, J.; Weidenhielm, L.; Persson, A.

    2016-01-01

    Objectives Computed tomography (CT) plays an important role in evaluating wear and periacetabular osteolysis (PAO) in total hip replacements. One concern with CT is the high radiation exposure since standard pelvic CT provides approximately 3.5 millisieverts (mSv) of radiation exposure, whereas a planar radiographic examination with three projections totals approximately 0.5 mSv. The objective of this study was to evaluate the lowest acceptable radiation dose for dual-energy CT (DECT) images when measuring wear and periacetabular osteolysis in uncemented metal components. Materials and Methods A porcine pelvis with bilateral uncemented hip prostheses and with known linear wear and acetabular bone defects was examined in a third-generation multidetector DECT scanner. The examinations were performed with four different radiation levels both with and without iterative reconstruction techniques. From the high and low peak kilo voltage acquisitions, polychrmoatic images were created together with virtual monochromatic images of energies 100 kiloelectron volts (keV) and 150 keV. Results We could assess wear and PAO while substantially lowering the effective radiation dose to 0.7 mSv for a total pelvic view with an accuracy of around 0.5 mm for linear wear and 2 mm to 3 mm for PAO. Conclusion CT for detection of prosthetic wear and PAO could be used with clinically acceptable accuracy at a radiation exposure level equal to plain radiographic exposures. Cite this article: B. Sandgren, M. Skorpil, P. Nowik, H. Olivecrona, J. Crafoord, L. Weidenhielm, A. Persson. Assessment of wear and periacetabular osteolysis using dual energy computed tomography on a pig cadaver to identify the lowest acceptable radiation dose. Bone Joint Res 2016;5:307–313. DOI: 10.1302/2046-3758.57.2000566. PMID:27445358

  15. GLOBIN-5-Dependent O2 Responses Are Regulated by PDL-1/PrBP That Targets Prenylated Soluble Guanylate Cyclases to Dendritic Endings

    PubMed Central

    Soltesz, Zoltan; Oda, Shigekazu; Zelmanovich, Veronica; Abergel, Zohar

    2014-01-01

    Aerobic animals constantly monitor and adapt to changes in O2 levels. The molecular mechanisms involved in sensing O2 are, however, incompletely understood. Previous studies showed that a hexacoordinated globin called GLB-5 tunes the dynamic range of O2-sensing neurons in natural C. elegans isolates, but is defective in the N2 lab reference strain (McGrath et al., 2009; Persson et al., 2009). GLB-5 enables a sharp behavioral switch when O2 changes between 21 and 17%. Here, we show that GLB-5 also confers rapid behavioral and cellular recovery from exposure to hypoxia. Hypoxia reconfigures O2-evoked Ca2+ responses in the URX O2 sensors, and GLB-5 enables rapid recovery of these responses upon re-oxygenation. Forward genetic screens indicate that GLB-5's effects on O2 sensing require PDL-1, the C. elegans ortholog of mammalian PrBP/PDE6δ protein. In mammals, PDE6δ regulates the traffic and activity of prenylated proteins (Zhang et al., 2004; Norton et al., 2005). PDL-1 promotes localization of GCY-33 and GCY-35, atypical soluble guanylate cyclases that act as O2 sensors, to the dendritic endings of URX and BAG neurons, where they colocalize with GLB-5. Both GCY-33 and GCY-35 are predicted to be prenylated. Dendritic localization is not essential for GCY-35 to function as an O2 sensor, but disrupting pdl-1 alters the URX neuron's O2 response properties. Functional GLB-5 can restore dendritic localization of GCY-33 in pdl-1 mutants, suggesting GCY-33 and GLB-5 are in a complex. Our data suggest GLB-5 and the soluble guanylate cyclases operate in close proximity to sculpt O2 responses. PMID:25505325

  16. The Far-UV Albedo of the Moon Determined from Dayside LAMP Observations

    NASA Astrophysics Data System (ADS)

    Bullock, Mark A.; Retherford, K. D.; Gladstone, R.; Greathouse, T. K.; Mandt, K. E.; Hendrix, A. R.; Feldman, P. D.; Miles, P. F.; Egan, A. F.

    2013-10-01

    The Lyman Alpha Mapping Project (LAMP) onboard the Lunar Reconnaissance Orbiter (LRO) has been recording far-UV photons reflected from the lunar surface almost continuously since December 2009 (Gladstone et al., 2010). One photon at a time, LAMP builds up spectra from 575 to 1965 Å with a resolution of 26 Å. We will present 3 years of accumulated LAMP lunar dayside spectral maps and derive the lunar geometric albedo spectrum for a range of phase angles. These LAMP observations can thus be used to reconstruct the lunar far-UV photometric function and refine photometric models of the lunar surface (Hapke, 1963; Lucke et al., 1976). We will also compare LAMP lunar dayside albedo with the albedo from 820-1840 Å obtained by the Hopkins Ultraviolet Telescope (HUT) on the March 1995 Astro-2 Space Shuttle mission (Henry et al., 1995). The improved lunar photometric functions from our analysis of LAMP albedo spectra will enable a better quantitative assessment of how phase angle and composition affect the Moon’s reflectance in the far-UV. Gladstone, G. R., Stern, S. A., Retherford, K. D., Black, R. K., Slater, D. C., Davis, M. W., Versteeg, M. H., Persson, K. B., Parker, J. W., Kaufmann, D. E., Egan, A. F., Greathouse, T. K., Feldman, P. D., Hurley, D., Pryor, W. R., Hendrix, A. R., 2010. LAMP: The lyman alpha mapping project on NASA's lunar reconnaissance orbiter mission. Space Science Reviews. 150, 161-181. Hapke, B. W., 1963. A theoretical photometric function for the lunar surface. Journal of Geophysical Research. 68, 4571-4586. Henry, R. C., Feldman, P. D., Kruk, J. W., Davidsen, A. F., Durrance, S. T., 1995. Ultraviolet Albedo of the Moon with the Hopkins Ultraviolet Telescope. The Astrophysical Journal Letters. 454, L69. Lucke, R. L., Henry, R. C., Fastie, W. G., 1976. Far-ultraviolet albedo of the moon. The Astronomical Journal. 81, 1162-1169.

  17. Velocity transition in the crack growth dynamics of filled elastomers: Contributions of nonlinear viscoelasticity

    NASA Astrophysics Data System (ADS)

    Morishita, Yoshihiro; Tsunoda, Katsuhiko; Urayama, Kenji

    2016-04-01

    The crack growth dynamics of the carbon-black (CB) filled elastomers is studied experimentally and analyzed while focusing on both kinetics and crack tip profiles. The CB amounts are varied to change the mechanical properties of the elastomers. Static crack growth measurements simultaneously reveal the discontinuous-like transition of the crack growth rate v between the "slow mode" (v ≈10-5-10-3 m/s) and "fast mode" (v ≈10-1-102 m/s) in a narrow range of the input tearing energy Γ and the accompanying changes in the crack tip profiles from blunt to sharp shapes. The crack tip profiles are characterized by two specific parameters, i.e., the deviation δ from the parabolic profile and the opening displacement a in the loading direction. The analysis based on the linear and weakly nonlinear elasticity theories of fracture dynamics demonstrates that the Γ dependence of δ and a is simply classified into three groups depending on the mode (slow or fast) and the magnitudes of δ , independent of CB volume fractions. The theories well explain the results in the slow and fast modes with small magnitudes of δ , while they fail to describe the data in the fast mode with large magnitudes of δ , where the contributions of the strong nonlinearity and/or energy dissipation become significant. The correlation between a power-law relationship Γ ˜vα observed in the fast mode and the linear viscoelasticity spectrum is also discussed. The correlation in elastomers with low CB volume fractions is quantitatively explained by the theory of Persson and Brener [Phys. Rev. E 71, 036123 (2005), 10.1103/PhysRevE.71.036123], whereas the deviation from the theory becomes appreciable for elastomers with higher CB volume fractions which exhibit strong nonlinear viscoelasticity.

  18. Correlation in double ionization of He by ultrashort pulses

    NASA Astrophysics Data System (ADS)

    Feist, Johannes

    2008-05-01

    Double ionization of helium has long been of considerable interest in atomic physics since it provides insight into the role of electronic correlation in the full three-body Coulomb break-up process, which is of fundamental importance for the understanding of the dynamics in more complex atoms. The recent availability of attosecond XUV pulses allows to directly probe and possibly control the temporal structure of the ionization process. We have implemented an ab initio simulation of the interaction of ultrashort laser pulses with a helium atom. The wave function is represented in a time-dependent close- coupling (TDCC) scheme and time integration is performed utilizing the Arnoldi-Lanczos method. The spatial discretization employs an FEDVR basis, which lends itself to effective parallelization. We will present results on two-photon double ionization of He by ultrashort pulses over a wide range of photon energies. At low energies only non-sequential double ionization is possible (where both electrons share the energy of the photons, and consequently have to be ionized within a short period). For photon energies above 54.4,V (the ionization potential of the He^+ ground state), sequential double ionization is allowed. This process proceeds in two steps -- single ionization of He followed by ionization of the remaining He^+ ion. By using attosecond XUV pulses, these two separated stages of the sequential process are confined to within a short time interval of each other. We show that the angular distributions of the emitted electrons reveal the signature of a non-sequential process under the condition that sufficiently short pulses are used, while for longer pulses the sequential process completely dominates. The correlation time for double ionization can thus be directly observed using attosecond XUV pulses. This work was performed in collaboration with S. Nagele, R. Pazourek, E. Persson, B. I. Schneider, L. A. Collins, and J. Burgd"orfer.

  19. 210Pb dating

    USGS Publications Warehouse

    Swarzenski, Peter W.

    2014-01-01

    Roughly fifty years ago, a small group of scientists from Belgium and the United States, trying to better constrain ice sheet accumulation rates, attempted to apply what was then know about environmental lead as a potential geochronometer. Thus Goldberg (1963) developed the first principles of the 210Pb dating method, which was soon followed by a paper by Crozaz et al. (1964), who examined accumulation history of Antarctic snow using 210Pb. Shortly thereafter, Koide et al. (1972, 1973) adapted this technique to unravel sediment deposition and accumulation records in deep-sea environments. Serendipitously, they chose to work in a deep basin off California, where an independent and robust age model had already been developed. Krishanswami et al. (1971) extended the use of this technique to lacustrine deposits to reconstruct depositional histories of lake sediment, and maybe more importantly, contaminant inputs and burial. Thus, the powerful tool for dating recent (up to about one century old) sediment deposits was established and soon widely adopted. Today almost all oceanographic or limnologic studies that address recent depositional reconstructions employ 210Pb as one of several possible geochronometers (Andrews et al., 2009; Gale, 2009; Baskaran, 2011; Persson and Helms, 2011). This paper presents a short overview of the principles of 210Pb dating and provides a few examples that illustrate the utility of this tracer in contrasting depositional systems. Potential caveats and uncertainties (Appleby et al., 1986; Binford, 1990; Binford et al., 1993; Smith, 2001; Hancock et al., 2002) inherent to the use and interpretation of 210Pb-derived age-models are also introduced. Recommendations as to best practices for most reliable uses and reporting are presented in the summary.

  20. Approach to voxel-based carbon stock quanticiation using LiDAR data in tropical rainforest, Brunei

    NASA Astrophysics Data System (ADS)

    Kim, Eunji; Piao, Dongfan; Lee, Jongyeol; Lee, Woo-Kyun; Yoon, Mihae; Moon, Jooyeon

    2016-04-01

    Forest is an important means to adapt climate change as the only carbon sink recognized by the international community (KFS 2009). According to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), Agriculture, Forestry, and Other Land Use (AFOLU) sectors including forestry contributed 24% of total anthropogenic emissions in 2010 (IPCC 2014; Tubiello et al. 2015). While all sectors excluding AFOLU have increased Greenhouse Gas (GHG) emissions, land use sectors including forestry remains similar level as before due to decreasing deforestation and increasing reforestation. In earlier researches, optical imagery has been applied for analysis (Jakubowski et al. 2013). Optical imagery collects spectral information in 2D. It is difficult to effectively quantify forest stocks, especially in dense forest (Cui et al. 2012). To detect individual trees information from remotely sensed data, Light detection and ranging (LiDAR) has been used (Hyyppäet al. 2001; Persson et al. 2002; Chen et al. 2006). Moreover, LiDAR has the ability to actively acquire vertical tree information such as tree height using geo-registered 3D points (Kwak et al. 2007). In general, however, geo-register 3D point was used with a raster format which contains only 2D information by missing all the 3D data. Therefore, this research aimed to use the volumetric pixel (referred as "voxel") approach using LiDAR data in tropical rainforest, Brunei. By comparing the parameters derived from voxel based LiDAR data and field measured data, we examined the relationships between them for the quantification of forest carbon. This study expects to be more helpful to take advantage of the strategic application of climate change adaption.

  1. Comparing Arctic Surface Energy Fluxes and Cloud Cover in the ERA-40, SHEBA, and Other Data Sets

    NASA Astrophysics Data System (ADS)

    Wheeler, C.; Persson, O. P.; Shupe, M.

    2008-12-01

    Earth's climate has been changing rapidly in the past few decades. The effects of climate change have been shown to be most noticeable in the Arctic (IPCC 2001). However, the Arctic environment is poorly understood due to several unique factors: relatively high surface albedo, absence of solar radiation during the polar night, extremely cold and dry conditions, and presence of temperature and humidity inversions. In order to understand the response of the Arctic to a changing climate, studies of trends, processes, and feedbacks utilize models and model-observation hybrid data sets. Hence, the accuracy of the processes and feedbacks in these data sets are important. In this study, surface radiative and turbulent fluxes from the ECMWF reanalysis data set (ERA-40; Uppala 2005) are examined from November 1997 through October 1998 over the Arctic Ocean, spanning from 73°N to 76°N latitude and 26°W to 36°W longitude. The reanalysis product is compared to observations taken at the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment (Persson et al. 2002), Russian drifting stations (Lindsay 1998), and the 'Maud' expedition (Sverdrup 1933). In general, the radiative fluxes in ERA-40 agree well with the observations, but with some exceptions that lead to significant differences in the net radiative surface flux and thus in the total surface energy budget. The ERA-40 turbulent fluxes have a similar annual pattern to the observations, but differ in magnitude, again contributing to the error seen in the total surface energy budget. Since clouds have one of the largest impacts on feedback mechanisms, cloud cover from ERA-40 is validated against cloud radar data collected at SHEBA. Finally, the observed relationships between cloud cover and surface fluxes in the SHEBA data are used to validate those in the ERA-40 data.

  2. A Receding Halo Sub-structure Towards Norma

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Sukanya

    2016-01-01

    We present results from follow-up spectroscopic observations of clustered Cepheid candidates identified from K-band light curves towards the Norma constellation (Chakrabarti et al. 2015), as well as others that we have found more recently. The average radial velocity of these stars is ~ 200 km/s, which is large and distinct from that of the Galaxy's stellar disk. These objects at l ~ -27 and b ~ -1 are therefore halo stars; using the period-luminosity relation of Type I Cepheids, they are at ~ 90 kpc. While the spectra do not have sufficient S/N to independently determine the metallicity and spectral type of the stars, there is a clear correspondence between the observed Brackett series lines in these observations and in known Type I Cepheids. Distances determined from the K-band period-luminosity relation (Matsunaga et al. 2013) and the 3.6 μm period-luminosity relation (Scowcroft et al. 2011) agree closely, and I-band observations have confirmed the periods of these sources. The extinction corrected J - Ks colors of these sources are comparable to known Type I Cepheids (Persson et al. 2004). The observed radial velocity of these stars agrees with predictions from dynamical models (Chakrabarti & Blitz 2009). If these stars are indeed members of the predicted dark-matter dominated dwarf galaxy that perturbed the outer HI disk of the Milky Way, this would represent the first application of Galactoseismology. These observations also challenge models of the Galactic halo. Young Cepheid variables are unexpected in models of the Galactic halo, though star formation due to infall of gas-rich dwarf galaxies may well produce a small population of yet undiscovered Cepheids in the outer halo.

  3. High Resolution Far Infrared Fourier Transform Spectroscopy of the NH_2 Radical.

    NASA Astrophysics Data System (ADS)

    Martin-Drumel, M. A.; Pirali, O.; Balcon, D.; Vervloet, M.

    2011-06-01

    First identified toward Sgr B2, the NH_2 radical has recently been detected in the interstellar medium by the HIFI instrument on board of Herschel. Despite the fact that this radical has not been detected in brown dwarfs and exoplanets yet, it is already included in physical and chemical models of those environments (temperature higher than 2000 K expected in several objects). Its detection in those objects will depend on the existence of a reliable high temperature and high resolution spectroscopic database on the NH_2 radical.The absorption spectrum of NH_2 has been recorded between 15 and 700 Cm-1 at the highest resolution available using the Bruker IFS125HR Fourier transform interferometer connected to the far infrared AILES beamline at SOLEIL (R=0.001 Cm-1). The radical was produced by an electrical discharge (DC) through a continuous flow of NH_3 and He using the White-type discharge cell developped on the beamline (optical path: 24m). Thanks to the brilliance of the synchrotron radiation, more than 700 pure rotational transitions of NH_2 have been identified with high N values (NMax=25) in its fundamental and first excited vibrational modes. By comparison to the previous FT spectroscopic study on that radical in the FIR spectral range, asymmetric splitting as well as fine and hyperfine structure have been resolved for several transitions. E. F. Van Dishoeck, D. J. Jansen, P. Schilke, T. G. Phillips The Astrophysical Journal 416, L83-L86 (1993) C. M. Persson, J. H. Black, J. Cernicharo et al. Astronomy and Astrophysics 521, L45 (2010) K. Lodders and B. Fegley, Jr Icarus 155, 393-424 (2002) I. Morino and K. Kawaguchi Journal of Molecular Spectroscopy 182, 428-438 (1997)

  4. Evaluation of New Fluorescent Lipophosphoramidates for Gene Transfer and Biodistribution Studies after Systemic Administration.

    PubMed

    Belmadi, Nawal; Berchel, Mathieu; Denis, Caroline; Berthe, Wilfried; Sibiril, Yann; Le Gall, Tony; Haelters, Jean-Pierre; Jaffres, Paul-Alain; Montier, Tristan

    2015-01-01

    The objective of lung gene therapy is to reach the respiratory epithelial cells in order to deliver a functional nucleic acid sequence. To improve the synthetic carrier's efficacy, knowledge of their biodistribution and elimination pathways, as well as cellular barriers faced, depending on the administration route, is necessary. Indeed, the in vivo fate guides the adaptation of their chemical structure and formulation to increase their transfection capacity while maintaining their tolerance. With this goal, lipidic fluorescent probes were synthesized and formulated with cationic lipophosphoramidate KLN47 (KLN: Karine Le Ny). We found that such formulations present constant compaction properties and similar transfection results without inducing additional cytotoxicity. Next, biodistribution profiles of pegylated and unpegylated lipoplexes were compared after systemic injection in mice. Pegylation of complexes led to a prolonged circulation in the bloodstream, whereas their in vivo bioluminescent expression profiles were similar. Moreover, systemic administration of pegylated lipoplexes resulted in a transient liver toxicity. These results indicate that these new fluorescent compounds could be added into lipoplexes in small amounts without perturbing the transfection capacities of the formulations. Such additional properties allow exploration of the in vivo biodistribution profiles of synthetic carriers as well as the expression intensity of the reporter gene. PMID:26540038

  5. Scientists Outline Volcanic Ash Risks to Aviation

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-01-01

    The ash clouds that belched out of Iceland's Eyjafjallajökull volcano last spring and dispersed over much of Europe, temporarily paralyzing aviation, were vast smoke signal warnings about the hazard that volcanic ash poses for air traffic around the world. At a 15 December news briefing at the AGU Fall Meeting in San Francisco, two experts with the U.S. Geological Survey (USGS) presented an overview of the damage airplanes can sustain from rock fragment- and mineral fragment-laden ash, an update on efforts to mitigate the hazard of ash, and an outline of further measures that are needed to address the problem. Between 1953 and 2009, there were 129 reported encounters of aircraft with volcanic ash clouds, according to a newly released USGS document cited at the briefing. The report, “Encounters of aircraft with volcanic ash clouds: A compilation of known incidents, 1953-2009,” by Marianne Guffanti, Thomas Casadevall, and Karin Budding, indicates that 26 encounters involved significant damage to the airplanes; nine of those incidents resulted in engine shutdown during flight. The report, which does not focus on the effects on airplanes of cumulative exposure to dilute ash and does not include data since 2009, indicates that “ash clouds continue to pose substantial risks to safe and efficient air travel globally.”

  6. FPA helps 33,000 young people get "sexwise".

    PubMed

    1995-01-01

    "Sexwise," an FPA information campaign for teens on sex and relationships, ran March 4-24 in London and Manchester, areas where teenage pregnancy rates are among the highest in England. It was sponsored by the Department of Health in support of "The health of the nation" goal of reducing teenage pregnancies in England by 50% by the year 2000. The average age of first sexual intercourse is 17 years. Although 94% of young people feel their parents should be their primary sources of sex information, they actually receive most of it from their friends and the media. One-eighth of teenage mothers surveyed by FPA and Middlesex University said that they only discussed contraception with their parents after they became pregnant. According to Karin Pappenheim, FPA Head of Publicity, the FPA wants to "enable young people to make informed decisions about whether and when to have sex while giving them the facts they need to avoid unplanned pregnancy and sexually transmitted diseases." Radio advertisements, which were produced by Laing Henry and featured Terry Christian (presenter for "The Word" on channel 4) and LTB (rappers), publicized the "Sexwise" helpline. Calls were free and confidential. Free copies of the FPA booklet, "Sexuality," were available upon request. Ads also appeared in "Just 17" and "Big," and on posters in Manchester pubs, clubs, and discos. PMID:12319464

  7. [The "top ten" of Finnish medicine].

    PubMed

    Leikola, A

    1998-01-01

    In the early 1980s the Wellcome Institute was planning a biographical dictionary on the world's most eminent physicians. The quota reserved for Finland was ten names, and having been asked by Dr. Karin Johannisson, Uppsala, to participate in the project, I undertook the task of choosing them and providing a short biography of each. For this, I asked the advice of ten experts on the history of Finnish medicine, and a "top ten" list was then compiled. The list extended from Johan Haartman, "the father of Finnish medicine", till the Nobel Prize winner Ragnar Granit and the famous pediatrist Arvo Ylppo, who were still alive in the 1980s. The biographies were sent to the editor of the dictionary, but it seems that the work was never published. As I had saved all my correspondence about the matter, it seemed now, fifteen years afterwards, interesting to publish a short report of the project, including an account of how the "top ten" list had been achieved. PMID:11625413

  8. Extended Solar System Structures Observed by WISE

    NASA Astrophysics Data System (ADS)

    Sykes, Mark V.; Masci, Frank; Cutri, Roc; Walker, Russell; Mainzer, Amy; Bauer, James; Stevenson, Rachel; Tricarico, Pasquale

    2014-11-01

    Extended structures associated with recent asteroid collisions and comets were detected by the Infrared Astronomical Satellite, which conducted the first survey of the thermal emission of the sky in 1983. Twenty-seven years later, the Wide-field Infrared Survey Explorer (WISE), conducted a more sensitive survey of the sky at wavelengths spanning the shorter IRAS bandpasses and detected many of these same structures. Initial identifications include asteroid dust bands associated with collisions giving rise to the Karin and Beagle clusters within the Koronis and Themis asteroid families, respectively. An additional pair of bands is associated with the collision giving rise to the Veritas asteroid family. Comet trails associated with short-period comets have also been observed. Type 2 trails, detected by IRAS and possibly associated with asteroid collisions within the past few thousand years, have yet to be identified. Because WISE is significantly more sensitive than IRAS in the mid-infrared, it has detected some trails extending much further over their orbits and will greatly expand the catalog of trails detected in addition to those observed by IRAS and Spitzer (the latter by targeted observations). WISE and the yet more sensitive NEOCAM survey telescope will provide important insights into the recent collisional history of the asteroid belt and the nature and evolution of comets.

  9. Reversible Avalanches and Criticality in Amorphous Solids

    NASA Astrophysics Data System (ADS)

    Reichhardt, Charles

    2015-03-01

    Despite its importance for basic science and industry, the physical process that causes a solid to change its shape permanently under external deformation is still not well understood. In this paper we use molecular dynamics simulations of amorphous solids under oscillatory shear to study this phenomenon, and show that at a critical strain amplitude, the size of the cooperative atomic motion that allows for a permanent deformation diverges. We compare this non-equilibrium critical behavior to that of a ``front depinning'' transition. This viewpoint, based on fluctuations and statistics, is complementary to the dynamical ``transition to chaos'' which was previously identified at the same strain amplitude. Below this irreversibile-depinning transition, we observe large avalanches which are completely repetitive with each shear strain cycle. This suggests that while avalanches on their own do not cause irreversible deformation, it is likely that the irreversibility transition and the ``depinning-like'' transition are two aspects of the same phenomena. One implication is that the transition could be detected before the onset of irreversible flow by an analysis of the power spectra of avalanches. Work done in collaboration with Ido Regev, Karin Dahmen, John Weber, and Turab Lookman.

  10. Yarkovsky/YORP chronology of asteroid families

    NASA Astrophysics Data System (ADS)

    Vokrouhlický, D.; Brož, M.; Bottke, W. F.; Nesvorný, D.; Morbidelli, A.

    2006-05-01

    Asteroid families are the byproducts of catastrophic collisions whose fragments form clusters in proper semimajor axis, eccentricity, and inclination space. Although many families have been observed in the main asteroid belt, only two very young families, Karin and Veritas, have well-determined ages. The ages of other families are needed, however, if we hope to infer information about their ejection velocity fields, space weathering processes, etc. In this paper, we developed a method that allows us to estimate the ages of moderately young asteroid families (approximately in between 0.1 and 1 Gyr). We apply it to four suitable cases—Erigone, Massalia, Merxia, and Astrid—and derive their likely ages and approximate ejection velocity fields. We find that Erigone and Merxia were produced by large catastrophic disruption events (i.e., parent body ⩾100 km) that occurred approximately 280 and 330 Myr ago, respectively. The Massalia family was likely produced by a cratering event on Asteroid (20) Massalia less than 200 Myr ago. Finally, the Astrid family, which was produced by the disruption of a 60-70 km asteroid, is 100-200 Myr old, though there is considerable uncertainty in this result. We estimate that the initial ejection velocities for these families were only a few tens of meters per second, consistent with numerical hydrocode models of asteroid impacts. Our results help to verify that asteroid families are constantly undergoing dynamical orbital evolution from thermal (Yarkovsky) forces and spin vector evolution from thermal (YORP) torques.

  11. Asteroid family classification from very large catalogues

    NASA Astrophysics Data System (ADS)

    Lemaitre, Anne

    2005-02-01

    The paper presents a review of the recent contributions and open questions concerning the families of asteroids. Due to the availability of very large catalogues (synthetic and analytical proper elements of the asteroids and large observational surveys of their spectra) and to the introduction of non gravitational forces in their determination, the concept of static family has disappeared, to be replaced by this of dynamical families. The proper elements are not constant anymore but are ageing on very long timescales. The size distributions of the populations of asteroids, in and out the families, their ages, the ejection velocities of the fragments after an impact, have been reconsidered by several teams of research, with this new approach. Parallel numerical simulations of collisions and fragmentations of bodies have showed that most of the asteroids are likely rubble piles or agglomerates than monolithic blocks. The methods of classification have been refined and combine, in their newest versions, the dynamics and the observations, working now on 5 dimensional space instead of 3. A series of sub families of the large well-known families have been recently identified, using catalogues with more than 100 000 asteroids (the cluster Karin for example).

  12. Evaluation of New Fluorescent Lipophosphoramidates for Gene Transfer and Biodistribution Studies after Systemic Administration

    PubMed Central

    Belmadi, Nawal; Berchel, Mathieu; Denis, Caroline; Berthe, Wilfried; Sibiril, Yann; Le Gall, Tony; Haelters, Jean-Pierre; Jaffres, Paul-Alain; Montier, Tristan

    2015-01-01

    The objective of lung gene therapy is to reach the respiratory epithelial cells in order to deliver a functional nucleic acid sequence. To improve the synthetic carrier’s efficacy, knowledge of their biodistribution and elimination pathways, as well as cellular barriers faced, depending on the administration route, is necessary. Indeed, the in vivo fate guides the adaptation of their chemical structure and formulation to increase their transfection capacity while maintaining their tolerance. With this goal, lipidic fluorescent probes were synthesized and formulated with cationic lipophosphoramidate KLN47 (KLN: Karine Le Ny). We found that such formulations present constant compaction properties and similar transfection results without inducing additional cytotoxicity. Next, biodistribution profiles of pegylated and unpegylated lipoplexes were compared after systemic injection in mice. Pegylation of complexes led to a prolonged circulation in the bloodstream, whereas their in vivo bioluminescent expression profiles were similar. Moreover, systemic administration of pegylated lipoplexes resulted in a transient liver toxicity. These results indicate that these new fluorescent compounds could be added into lipoplexes in small amounts without perturbing the transfection capacities of the formulations. Such additional properties allow exploration of the in vivo biodistribution profiles of synthetic carriers as well as the expression intensity of the reporter gene. PMID:26540038

  13. Ab initio DFT calculations of vibrational properties

    NASA Astrophysics Data System (ADS)

    Story, S. M.; Vila, F. D.; Kas, J. J.; Rehr, J. J.

    2014-03-01

    Vibrational properties such as EXAFS and crystallographic Debye-Waller factors, vibrational free energies, phonon self-energies, and phonon contributions to the electron spectral function, are key to understanding many aspects of materials beyond ground state electronic structure. Thus, their simulation using first principles methods is of particular importance. Many of these vibrational properties can be calculated from the dynamical matrix and electron-phonon coupling coefficients obtained from DFT calculations. Here we present a code DMVP that calculates these properties from the output of electronic structure codes such as ABINIT, Gaussian, Quantum Espresso and VASP. Our modular interfacing tool AI2PS allows us to translate the different outputs into a DMVP compatible format and generate vibrational properties in an automated way. Finally, we present some current applications that take advantage of the modular form of AI2PS to extend its capabilities to the calculation of coefficients of thermal expansion and other properties of interest such as infrared spectra. This work was supported by DOE Grant DE-FG02-97ER45623.

  14. [A history of the electrocardiogram].

    PubMed

    Johansson, B W

    2001-01-01

    The discoveries by Galvani and Volta of electricity and its effects fascinated the intellectual world, but it was not until 1856 that Köllicker and Müller discovered that the heart muscle could produce electric activity. Muirhead in London recorded the first electrocardiogram (ECG) in man in 1869 or 1870 with a siphon instrument and Waller in 1887 with a capillary electrometer. Einthoven's string galvanometer was a breakthrough. As early as five years after his publication Einthoven introduced "Le Télecardiograme" in 1906 by which a cable connected his instrument to a hospital one and a half kilometres away. The string galvanometer produced precise ECG recordings but it was like the opera primadonnas of the time, voluminous and unpredictable. Rune Elmqvist developed the direct-writing inkjet recorder, first demonstrated at the Congress of Cardiology in Paris, 1950. Ohnell's studies of preexcitation, to which the WPW-syndrome belongs, were important. After the initial focus on arrhythmias, ECG became more and more used in the diagnosis of myocardial ischaemia and coronary heart disease. To refine this diagnosis the hypoxaemia (breathing air with low oxygen content) test, as well as the exercise test and other stress tests were introduced. Vectorcardiography displays the spatial movements of the electrical forces generated by the heart. Long-term ECG registration with a portable tape recorder is important both for the diagnosis of arrhythmias and myocardial ischaemia. Foetal and comparative ECG have provided important clinical and scientific information. PMID:11848076

  15. [ECG mapping in clinical practice].

    PubMed

    Boudík, F; Aschermann, M; Anger, Z

    2002-12-01

    First the authors present a review of important cornerstones in the history of the electrocardiogram (ECG) and ECG mapping. The first to describe the electric cardiac field based on twenty ECGs was A.D. Waller in 1889. The decisive cornerstone for practical use was the introduction of a string galvanometer in 1901 by W. Einthoven and his triaxial lead system. Another very important cornerstone in the development of ECG were the findings of F.N. Wilson. Merits as regards the development and application of ECG mapping are due to B. Taccardi. Workers of the Second Medical Clinic in Prague enhanced after 15 years of studies and comparison of ECG maps with coronarographic findings in subjects with ischaemic heart disease (IHD) and microvascular coronary dysfunction (syndrome X--SyX) substantially the specificity of this method in impaired myocardial vascularization. Better diagnosis was achieved by introduction of diagnostic tests which influence coronary vascularization such as e.g. hyperventilation, as well as other tests. After their application progression of chronic myocardial ischaemia occurs, e.g. by the mechanism of the "steal phenomenon" or restriction of the microcirculation after hyperventilation in patients with SyX. Furthermore the authors present examples of ECG maps after PTCA, after application of diagnostic tests in IHD and SyX and also regression of myocardial ischaemia after marked reduction of total cholesterol. PMID:12744039

  16. Simulation of the EXAFS and Raman spectra of InxGa1-xN utilizing the equation of motion routine of FEFF8.

    NASA Astrophysics Data System (ADS)

    Katsikini, M.; Pinakidou, F.; Paloura, E. C.; Arvanitidis, J.; Ves, S.; Reinholz, U.; Papadomanolaki, E.; Iliopoulos, E.

    2016-05-01

    A combined analysis of EXAFS and Raman spectra is applied for the study of InxGa1-xN alloys with 0.3Waller factor (DWF). The static disorder component of the DWFs was obtained by fitting the Ga and In K-edge EXAFS spectra. The analysis revealed that the nearest neighbor distances of the 1st and 2nd shell deviate from the values predicted by the law of Vegard and the virtual crystal approximation. The static disorder in the first nearest neighboring shell (In-N and Ga-N) is null whereas in the cation-cation neighboring shells the static component is generally smaller than the vibrational.

  17. Ion-irradiation-induced amorphization of Cu nanoparticles embedded in SiO2

    NASA Astrophysics Data System (ADS)

    Johannessen, B.; Kluth, P.; Llewellyn, D. J.; Foran, G. J.; Cookson, D. J.; Ridgway, M. C.

    2007-11-01

    Elemental Cu nanoparticles embedded in SiO2 were irradiated with 5MeVSn3+ . The nanoparticle structure was studied as a function of Sn3+ fluence by extended x-ray absorption fine structure spectroscopy, small-angle x-ray scattering, and transmission electron microscopy. Prior to irradiation, Cu nanoparticles exhibited the face-centered-cubic structure. Upon irradiation at intermediate fluences ( 1×1013 to 1×1014ions/cm2 ), the first nearest neighbor Cu-Cu coordination number decreased, while the Debye-Waller factor, bondlength, and third cumulant of the bondlength distribution increased. In particular, at a fluence of 1×1014ions/cm2 we argue for the presence of an amorphous Cu phase, for which we deduce the structural parameters. Low temperature annealing (insufficient for nanoparticle growth) of the amorphous Cu returned the nanoparticles to the initial preirradiation structure. At significantly higher irradiation fluences ( 1×1015 to 1×1016ions/cm2 ), the nanoparticles were dissolved in the matrix with a Cu coordination similar to that of Cu2O .

  18. Vibrational neutron spectroscopy of collagen and model polypeptides.

    PubMed Central

    Middendorf, H D; Hayward, R L; Parker, S F; Bradshaw, J; Miller, A

    1995-01-01

    A pulsed source neutron spectrometer has been used to measure vibrational spectra (20-4000 cm-1) of dry and hydrated type I collagen fibers, and of two model polypeptides, polyproline II and (prolyl-prolyl-glycine)10, at temperatures of 30 and 120 K. the collagen spectra provide the first high resolution neutron views of the proton-dominated modes of a protein over a wide energy range from the low frequency phonon region to the rich spectrum of localized high frequency modes. Several bands show a level of fine structure approaching that of optical data. The principal features of the spectra are assigned. A difference spectrum is obtained for protein associated water, which displays an acoustic peak similar to pure ice and a librational band shifted to lower frequency by the influence of the protein. Hydrogen-weighted densities of states are extracted for collagen and the model polypeptides, and compared with published calculations. Proton mean-square displacements are calculated from Debye-Waller factors measured in parallel quasi-elastic neutron-scattering experiments. Combined with the collagen density of states function, these yield an effective mass of 14.5 a.m.u. for the low frequency harmonic oscillators, indicating that the extended atom approximation, which simplifies analyses of low frequency protein dynamics, is appropriate. PMID:8527680

  19. Controlling the dynamics of a bidimensional gel above and below its percolation transition

    NASA Astrophysics Data System (ADS)

    Orsi, D.; Ruta, B.; Chushkin, Y.; Pucci, A.; Ruggeri, G.; Baldi, G.; Rimoldi, T.; Cristofolini, L.

    2014-04-01

    The morphology and the microscopic internal dynamics of a bidimensional gel formed by spontaneous aggregation of gold nanoparticles confined at the water surface are investigated by a suite of techniques, including grazing-incidence x-ray photon correlation spectroscopy (GI-XPCS). The range of concentrations studied spans across the percolation transition for the formation of the gel. The dynamical features observed by GI-XPCS are interpreted in view of the results of microscopic imaging; an intrinsic link between the mechanical modulus and internal dynamics is demonstrated for all the concentrations. Our work presents an example of a transition from a stretched to a compressed correlation function actively controlled by quasistatically varying the relevant thermodynamic variable. Moreover, by applying a model proposed some time ago by Duri and Cipelletti [Europhys. Lett. 76, 972 (2006), 10.1209/epl/i2006-10357-4] we are able to build a master curve for the shape parameter, whose scaling factor allows us to quantify a "long-time displacement length." This characteristic length is shown to converge, as the concentration is increased, to the "short-time localization length" determined by pseudo-Debye-Waller analysis of the initial contrast. Finally, the intrinsic dynamics of the system is then compared with that induced by means of a delicate mechanical perturbation applied to the interface.

  20. Atomic structure and phason modes of the Sc–Zn icosahedral quasicrystal

    PubMed Central

    Yamada, Tsunetomo; Takakura, Hiroyuki; Euchner, Holger; Pay Gómez, Cesar; Bosak, Alexei; Fertey, Pierre; de Boissieu, Marc

    2016-01-01

    The detailed atomic structure of the binary icosahedral (i) ScZn7.33 quasicrystal has been investigated by means of high-resolution synchrotron single-crystal X-ray diffraction and absolute scale measurements of diffuse scattering. The average atomic structure has been solved using the measured Bragg intensity data based on a six-dimensional model that is isostructural to the i-YbCd5.7 one. The structure is described with a quasiperiodic packing of large Tsai-type rhombic triacontahedron clusters and double Friauf polyhedra (DFP), both resulting from a close-packing of a large (Sc) and a small (Zn) atom. The difference in chemical composition between i-ScZn7.33 and i-YbCd5.7 was found to lie in the icosahedron shell and the DFP where in i-ScZn7.33 chemical disorder occurs on the large atom sites, which induces a significant distortion to the structure units. The intensity in reciprocal space displays a substantial amount of diffuse scattering with anisotropic distribution, located around the strong Bragg peaks, that can be fully interpreted as resulting from phason fluctuations, with a ratio of the phason elastic constants K 2/K 1 = −0.53, i.e. close to a threefold instability limit. This induces a relatively large perpendicular (or phason) Debye–Waller factor, which explains the vanishing of ‘high-Q perp’ reflections. PMID:27437112

  1. Assessing the feasibility of low temperature XAFS experiments at Indus-2, India: First results

    NASA Astrophysics Data System (ADS)

    Ramanan, Nitya; Rajput, Parasmani; Jha, S. N.; Lahiri, Debdutta

    2015-05-01

    In this work, we report installation of displex cryostat XAFS sample holder at XAFS beamline (BL-09) of Indus-2 synchrotron facility, India and make critical assessment of feasibility of low-temperature XAFS experiments in terms of data quality and reproducibility, temperature range, calibration and attainable resolution. We adopted the Debye Model-based calibration method by measuring XAFS of standard Au foil with known Debye temperature (ΘDebye)Autheory = 165 K. The data is of good quality and reproducible with international data. By fitting Debye Waller Factor (σexpt2 (T)), we deduced (ΘDebye)Auexpt = 163 K which implies calibration within 2 K. Error bars for σexpt2 (T) correspond to temperature uncertainty ΔT ≤ 5 K, which defines the temperature resolution for low temperature XAFS experiments. Thus, from both calibration and resolution points-of-view, this work demonstrates the feasibility of low temperature XAFS experiments at BL-09, Indus-2. Feasibility of extending XAFS experiments to lower temperature and unknown samples is discussed.

  2. Parallel calculations of vibrational properties in complex materials: negative thermal expansion and elastic inhomogeneity

    NASA Astrophysics Data System (ADS)

    Vila, F. D.; Rehr, J. J.

    Effects of thermal vibrations are essential to obtain a more complete understanding of the properties of complex materials. For example, they are important in the analysis and simulation of x-ray absorption spectra (XAS). In previous work we introduced an ab initio approach for a variety of vibrational effects, such as crystallographic and XAS Debye-Waller factors, Debye and Einstein temperatures, and thermal expansion coefficients. This approach uses theoretical dynamical matrices from which the locally-projected vibrational densities of states are obtained using a Lanczos recursion algorithm. In this talk I present recent improvements to our implementation, which permit simulations of more complex materials with up to two orders of magnitude larger simulation cells. The method takes advantage of parallelization in calculations of the dynamical matrix with VASP. To illustrate these capabilities we discuss two problems of considerable interest: negative thermal expansion in ZrW2O8; and local inhomogeneities in the elastic properties of supported metal nanoparticles. Both cases highlight the importance of a local treatment of vibrational properties. Supported by DOE Grant DE-FG02-03ER15476, with computer support from DOE-NERSC.

  3. The mediating role of anger in the relationship between PTSD symptoms and impulsivity.

    PubMed

    Contractor, Ateka A; Armour, Cherie; Wang, Xin; Forbes, David; Elhai, Jon D

    2015-03-01

    Research indicates a significant relationship between posttraumatic stress disorder (PTSD) and anger (Olatunji, Ciesielski, & Tolin, 2010; Orth & Wieland, 2006). Individuals may seek urgent coping to deal with the distress of anger, which is a mobilizing and action-oriented emotion (Novaco & Chemtob, 2002); possibly in the form of impulsive actions consistent with impulsivity's association with anger (Milligan & Waller, 2001; Whiteside & Lynam, 2001). This could be 1 of the explanations for the relationship between PTSD and impulsivity (Kotler, Julian, Efront, & Amir, 2001; Ledgerwood & Petry, 2006). The present study assessed the mediating role of anger between PTSD (overall scores and subscales of arousal and negative alterations in mood/cognitions) and impulsivity, using gender as a covariate of impulsivity. The PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), Dimensions of Anger Reaction scale-5, and the UPPS Impulsivity Scale were administered to a sample of 244 undergraduate students with a trauma history. Results based on 1000 bootstrapped samples indicated significant direct effects of PTSD (overall and 2 subscales) on anger, of anger on impulsivity, and of PTSD (overall and 2 subscales) on impulsivity. Further, anger significantly mediated the relationship between PTSD (overall and 2 subscales) and impulsivity, consistent with the hypothesized models. Results suggest that impulsivity aims at coping with distressing anger, possibly explaining the presence of substance usage, and other impulsive behaviors in people with PTSD. Further, anger probably serves as a mobilizing and action-oriented emotion coupled with PTSD symptoms. PMID:25793689

  4. Mössbauer Effect in Hemoglobin and Some Iron-Containing Biological Compounds

    PubMed Central

    Gonser, U.; Grant, R. W.

    1965-01-01

    The Mössbauer effect in Fe57 has been used to study the molecules, hemoglobin, O2-hemoglobin, CO2-hemoglobin, and CO-hemoglobin (within red cells) and the molecules, hemin and hematin (in the crystalline state). Quadrupole splittings and isomeric shifts observed in the Mössbauer spectra of these molecules are tabulated. The temperature dependence of the quadrupole splitting and relative recoil-free fraction for hemoglobin with different ligands has been investigated. An estimate of the Debye-Waller factor in O2-hemoglobin at 5°K is 0.83. An asymmetry in the quadrupole splitting observed in hemoglobin is attributed to a directional dependence of the recoil-free fraction which establishes the sign of the electric field gradient in the molecule and indicates that the lowest lying d orbital of the Fe atoms is |xy>. This asymmetry indicates that the iron atoms in hemoglobin are vibrating farther perpendicular to the heme planes than parallel to them, and, in fact, the ratio of the mean square displacements perpendicular and parallel to the heme planes in hemoglobin is ≈5.5 at 5°K. The temperature dependence of the quadrupole splitting in hemoglobin has been used to estimate a splitting between the lowest lying iron atom d orbitals of ≈420 cm-1. PMID:5884013

  5. Clinicians' judgments of clinical utility: a comparison of the DSM-IV with dimensional models of general personality.

    PubMed

    Lowe, Jennifer Ruth; Widiger, Thomas A

    2009-06-01

    Clinical utility, or the usefulness of a diagnostic system in clinical practice, has been identified as a potential limitation of alternative dimensional models of personality disorder, such as the five-factor model (FFM; McCrae & Costa, 1990), the Temperament and Character Inventory (TCI; Cloninger, 2000), the Multidimensional Personality Questionnaire (MPQ; Tellegen & Waller, 1987), and the Shedler & Westen Assessment Procedure-200 (SWAP-200; Shedler & Westen, 1998). Both proponents of and opponents to dimensional models of personality disorder have suggested that their clinical utility be assessed in preparation for DSM-V (e.g., Rounsaville et al., 2002; First et al., 2002; Verheul, 2005; First, 2005). Samuel & Widiger (2006) found the FFM to have significantly greater clinical utility than the existing diagnostic categories. In the current study, 1,572 practicing psychologists were asked to describe one of three cases using the DSM-IV and the constructs of one of four alternative dimensional models (FFM, TCI, MPQ, SWAP). Clinicians then rated each model on six aspects of clinical utility. Results indicate that clinicians find dimensional models to be higher in clinical utility than the DSM-IV on five of the six aspects of clinical utility, but not significantly different from each other. Implications of these findings are discussed. PMID:19538078

  6. The Recaptured Scale Technique: A Method for Testing the Structural Robustness of Personality Scales.

    PubMed

    Waller, Niels G; DeYoung, Colin G; Bouchard, Thomas J

    2016-01-01

    Tellegen and Waller advocated a complex and time-consuming scale construction method that they called "exploratory test construction." Scales that are constructed by this method-such as the Multidimensional Personality Questionnaire (MPQ)-are presumed to be more "psychologically coherent" and "robust" than scales constructed by other means. Using a novel procedure that we call the "recaptured scale technique," we tested this conjecture by conducting a megafactor analysis on data from the 411 adult participants of the Minnesota Study of Twins Reared Apart who completed the MPQ, the MMPI, and the CPI. We extracted and obliquely rotated 21 factors from a matrix of gender-corrected tetrachoric correlations for the 1,102 nonredundant items of the three omnibus inventories. Robustness of the 11 MPQ scales was assessed by the degree to which these factors recaptured the MPQ item groupings. Our results showed that nine factors were clearly recognizable as MPQ scales and two additional factors represented a bifurcation of an MPQ scale. A higher-order factor analysis of all 21 factor scales yielded five factors that clearly resembled the Big Five. Our results provide strong support for (a) the method of exploratory test construction, (b) the structural robustness of most MPQ scales, and PMID:27191377

  7. Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X  =  S, Se, Te).

    PubMed

    Caramazza, S; Marini, C; Simonelli, L; Dore, P; Postorino, P

    2016-08-17

    The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo-X, Mo-Mo and X-X (X  =  S, Se, and Te) and of the corresponding Debye-Waller factors have been extracted over the 70-500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo-X and X-X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo-X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2. PMID:27345937

  8. Delineating the Construct Network of the Personnel Reaction Blank: Associations with Externalizing Tendencies and Normal Personality

    PubMed Central

    Blonigen, Daniel M.; Patrick, Christopher J.; Gasperi, Marianna; Steffen, Benjamin; Ones, Deniz S.; Arvey, Richard D.; de Oliveira Baumgartl, Viviane; do Nascimento, Elizabeth

    2010-01-01

    Integrity testing has long been utilized in personnel selection to screen for tendencies toward counterproductive workplace behaviors. The construct of externalizing from the psychopathology literature represents a coherent spectrum marked by disinhibitory traits and behaviors. The present study used a sample of male and female undergraduates to examine the construct network of the Personnel Reaction Blank (PRB; Gough, Arvey, & Bradley, 2004), a measure of integrity, in relation to externalizing as well as normal-range personality constructs assessed by the Multidimensional Personality Questionnaire (MPQ; Tellegen & Waller, 2008). Results revealed moderate to strong associations between several PRB scales and externalizing, which were largely accounted for by MPQ traits subsumed by Negative Emotionality and Constraint. After accounting for MPQ traits in the prediction of externalizing, a modest predictive increment was achieved when adding the PRB scales, particularly biographical indicators from the Prosocial Background subscale. The findings highlight externalizing as a focal criterion for scale development in the integrity testing literature, and help delineate the construct network of the PRB within the domains of personality and psychopathology. PMID:21171783

  9. High-resolution elastic and rotationally inelastic diffraction of D2 from NiAl(110)

    NASA Astrophysics Data System (ADS)

    Barredo, Daniel; Laurent, Guillaume; Nieto, Pablo; Farías, Daniel; Miranda, Rodolfo

    2010-09-01

    High-resolution angular distributions of D2 scattered from NiAl(110) have been measured at incident energies between 20 and 150 meV. The measurements were performed along the [11¯0] azimuth using a high sensitivity time-of-flight apparatus, which allows the recording of diffraction channels not previously studied, including out-of-plane rotationally inelastic diffraction peaks. The attenuation of both elastic and rotationally inelastic diffraction intensities with surface temperature was found to follow a Debye-Waller model. The time-of-flight data analysis allowed us to assign unequivocally the different transition probabilities to each final state. In this way, 0→2, 2→0, and 1→3 transition probabilities were observed, covering relative intensities over two orders of magnitude. In the energy range investigated, the 0→2 transition was found to be a factor of 2-3 larger than the 2→0 one, which lies a factor of 10 above the 1→3 transition probability.

  10. Nanoscale heat transport from Ge hut, dome, and relaxed clusters on Si(001) measured by ultrafast electron diffraction

    SciTech Connect

    Frigge, T. Hafke, B.; Tinnemann, V.; Krenzer, B.; Horn-von Hoegen, M.

    2015-02-02

    The thermal transport properties of crystalline nanostructures on Si were studied by ultra-fast surface sensitive time-resolved electron diffraction. Self-organized growth of epitaxial Ge hut, dome, and relaxed clusters was achieved by in-situ deposition of 8 monolayers of Ge on Si(001) at 550 °C under UHV conditions. The thermal response of the three different cluster types subsequent to impulsive heating by fs laser pulses was determined through the Debye-Waller effect. Time resolved spot profile analysis and life-time mapping was employed to distinguish between the thermal response of the different cluster types. While dome clusters are cooling with a time constant of τ = 150 ps, which agrees well with numerical simulations, the smaller hut clusters with a height of 2.3 nm exhibit a cooling time constant of τ = 50 ps, which is a factor of 1.4 slower than expected.

  11. Design rules for rational control of polymer glass formation behavior and mechanical properties with small molecular additives

    NASA Astrophysics Data System (ADS)

    Mangalara, Jayachandra Hari; Simmons, David

    Small molecule additives have long been employed to tune polymers' glass formation, mechanical and transport properties. For example, plasticizers are commonly employed to suppress polymer Tg and soften the glassy state, while antiplasticizers, which stiffen the glassy state of a polymer while suppressing its Tg, are employed to enhance protein and tissue preservation in sugar glasses. Recent literature indicates that additives can have a wide range of possible effects, but all of these have not been clearly understood and well appreciated. Here we employ molecular dynamics simulations to establish design rules for the selection of small molecule additives with size, molecular stiffness, and interaction energy chosen to achieve targeted effects on polymer properties. We furthermore find that a given additive's effect on a polymer's Tg can be predicted from its Debye-Waller factor via a function previously found to describe nanoconfinement effects on the glass transition. These results emphasize the potential for a new generation of targeted molecular additives to contribute to more targeted rational design of polymers. We acknowledge the Keck Foundation and the Ohio Supercomputing Center for financial and computational support of this effort, respectively.

  12. Experimental evidence for an absorbing phase transition underlying yielding of a soft glass

    NASA Astrophysics Data System (ADS)

    Nagamanasa, K. Hima; Gokhale, Shreyas; Sood, A. K.; Ganapathy, Rajesh

    2014-03-01

    A characteristic feature of solids ranging from foams to atomic crystals is the existence of a yield point, which marks the threshold stress beyond which a material undergoes plastic deformation. In hard materials, it is well-known that local yield events occur collectively in the form of intermittent avalanches. The avalanche size distributions exhibit power-law scaling indicating the presence of self-organized criticality. These observations led to predictions of a non-equilibrium phase transition at the yield point. By contrast, for soft solids like gels and dense suspensions, no such predictions exist. In the present work, by combining particle scale imaging with bulk rheology, we provide a direct evidence for a non-equilibrium phase transition governing yielding of an archetypal soft solid - a colloidal glass. The order parameter and the relaxation time exponents revealed that yielding is an absorbing phase transition that belongs to the conserved directed percolation universality class. We also identified a growing length scale associated with clusters of particles with high Debye-Waller factor. Our findings highlight the importance of correlations between local yield events and may well stimulate the development of a unified description of yielding of soft solids.

  13. Ab initio calculations of phonon properties and spectra in condensed matter

    NASA Astrophysics Data System (ADS)

    Story, Shauna M.

    Phonons, the quantization of atomic vibrations, are important in studying many solid state properties, ranging from Raman, infrared, and neutron scattering to thermal expansion, specific heat, and heat conductivity to electrical resistivity and superconductivity. Generally, modeling the interatomic forces and vibrational modes of a given system require costly computer simulations, though once calculated, they provide the means to a wide variety of phonon properties. Our goal is to enable easy access to these phonon properties and to do this, we have developed a framework for easily automating the workflows involved in interfacing a phonon mode calculation with the analysis tools for determining such physical properties. This was originally implemented with the AI2PS (ab initio to phonon spectra) tool, meant solely for the calculation of vibrational properties. It has since greatly expanded in scope and capabilities to a general scientific workflow tool called Corvus, which was started with the eventual goal of collecting all our various scientific workflow efforts---phonon properties, optical properties, and so on---into a single hub. We present here both the evolution of AI2PS into the Corvus project and the phonon properties simulated, including Debye--Waller factors, phonon contributions the electron self--energy and spectral function, vibrational free energy, thermal expansion, and heat capacity.

  14. X-ray specular scattering from statistically rough surfaces: a novel theoretical approach based on the Green function formalism.

    PubMed

    Chukhovskii, F N; Polyakov, A M

    2010-11-01

    The Green function formalism is applied to the problem of grazing-incidence small-angle X-ray scattering from statistically rough surfaces. Kirchhoff's integral equation is used to describe the X-ray wavefield propagation through a single rough surface separating vacuum and medium. Taking into account multiple diffuse X-ray scattering effects, the reflection R(coh)(θ) and transmission T(coh)(θ) coefficients of the specular wave are obtained using the Gaussian statistical model of rough surfaces in terms of the two-point height-height correlation function. In the limiting cases when the correlation length xi is equal to zero or infinity, analytical formulae for the reflection R(coh)(θ) and transmission T(coh)(θ) coefficients of the specular wave are obtained. It is important that in the case xi --> infinity they coincide with the corresponding reflection R(DW)(θ) and transmission T(DW)(θ) coefficients related to the conventional Debye-Waller approximation for describing the grazing X-ray scattering from a rough surface. In the case of finite values of correlation length \\xi the reflection |R(coh)(θ)|(2) and transmission |T(coh)(θ)|(2) scans are numerically calculated. PMID:20962372

  15. "Your feet's too big": an inquiry into psychological and symbolic meanings of the foot.

    PubMed

    Zerbe, K J

    1985-01-01

    The foot is a highly cathected appendage that is commonly singled out as the brunt of humorous or derisive remarks, as if it embodies repugnance and disgust. Attitudes toward the foot are overdetermined, bearing the imprint of man's early linguistic patterns and individual dynamics. This article suggests that feet are symbolic because they bear the feelings derived from earlier separations, good and bad object representations, collective memories, and genital representations. The foot's role as symbol of both the male and female genitals, repository of badness, symbol of passivity, initiator of movement, and site of self-mutilation have been briefly reviewed. As Fats Waller rhapsodizes that the "feet's too big," he finds a convenient way to displace his symbiotic and erotic anxieties vis-à-vis women. Similarly, patients who come for psychiatric treatment and psychotherapy frequently make references to their feet or use them in specific ways. An understanding of this type of communication can often provide insight into individual dynamics and enhance treatment. The weight placed on these communications depends, of course, on the vicissitudes of the previous therapeutic work as well as on the particular problems of the patient. PMID:2413495

  16. Impact of Air Pollution on California Central Valley Fog Frequency

    NASA Astrophysics Data System (ADS)

    Gray, E.; Baldocchi, D. D.; Goldstein, A. H.

    2015-12-01

    Throughout the 20th century, trends in California Central Valley fog frequency have changed dramatically without explanation. While episodes of dense radiation fog, known regionally as Tule Fog, increased steadily from 1930-1970, analysis from both ground and remote sensing measurements confirm a 46-50% reduction in fog days in the last 30 years (Baldocchi and Waller, 2014, Herkes et al., 2014). The dominant hypotheses suggest that the recent decline in radiation fog can be explained by the rising temperatures associated with climate change or urban heat island effect. This assertion fails to explain the significant increase in Central Valley fog midcentury. Here we instead assert that changes in air pollution, rather than climate, better support this upward then downward temporal trend. Automobile use greatly increased emissions of nitrogen oxide (NOx) midcentury, followed by a large decrease in vehicle emissions due to statewide regulation from 1980 to present. In the Central Valley, NOx from automobile emissions contributes to the formation ammonium nitrate (NH4NO3), the dominant hygroscopic aerosol in the valley's wintertime boundary layer that can act as cloud condensation nuclei (CCN) necessary for fog droplet formation. Thus, changes in air pollution not only affect the number of CCN, but may also impact the density and persistence of fog episodes. Using NOAA meteorological records throughout the twentieth century, we will show the correlation between fog frequency, air pollution, and climatic drivers. We conclude that fog trends are closely correlated with changes in air pollution, rather than solely climate change.

  17. The effect of attachment insecurity in the development of eating disturbances across gender: the role of body dissatisfaction.

    PubMed

    Koskina, Nefeli; Giovazolias, Theodoros

    2010-01-01

    The present study examined the effects of insecure attachment on the development of negative body image as a contributing factor to the development of disturbed eating patterns in male and female university students. Participants were nonclinical male (n = 100) and female (n = 381) university students. Administering self-report questionnaires, the authors assessed demographic information (gender, age), anthropometric data (Body Mass Index [BMI], age), romantic attachment (ECRS-R; R. C. Fraley, N. G. Waller, & K. A. Brennan, 2000), body dissatisfaction (BSQ), and disturbed eating (EAT-26). The authors found body dissatisfaction to fully mediate the relationship between attachment anxiety and disordered eating in women. Body dissatisfaction mediated anxious attachment and dieting in men. In addition, attachment avoidance had a direct impact on eating behaviors for both genders, without the mediation of any variables measured in this study. The findings of the present study suggest that the anxiety and avoidance dimensions of attachment insecurity affect eating behaviors differently, and the effects are different across genders. The authors discuss results in the context of therapeutic interventions design. PMID:20806850

  18. The Surface Structure of Liquid Metals and Alloys

    NASA Astrophysics Data System (ADS)

    Pershan, Peter

    2004-03-01

    X-ray scattering of the surface structure of liquid metals and liquid metal alloys will be discussed. We will report observations of the theoretically predicted surface induced atomic layering; however, quantitative interpretation of the local surface structure factor requires that the Debye-Waller effect associated with thermal capillary waves be accounted for. We will explain how that is done. Results that will be described for surfaces that exhibit simple layering , such as Ga, In and K, will be contrasted with anomalous layering that is observed for Sn. In addition data on the surfaces of alloys such as GaBi, InBi, AuGe and AuSi will be presented This work is supported by DE-FG02-88-ER45379 and DMR-0124936. Experiments at BNL and CMC-Cat at the APS are supported by DE-AC02-98CH10886. Experiments at ChemMatCars at the APS are supported by NSF/DOE grant CHE0087817.

  19. Spectroscopic characterization of pigment binding proteins in normal-grown and iron-stressed thermophilic cyanobacteria Synecococcus sp.

    NASA Astrophysics Data System (ADS)

    Lovčinský, M.; Dědic, R.; Pšenčík, J.; Benešová, J.; Štys, D.; Hála, J.

    1999-05-01

    The results of low temperature absorption, fluorescence and hole burning spectroscopy of pigment binding proteins in normal-grown and iron-stressed thermophilic Synecococcus sp. are reported. These experiments revealed that the growing of Synecococcus sp. under the iron-limited condition affects spectral characteristics and excited energy transfer (EET) in pigment proteins. The comparison of low temperature absorption spectra of normal-grown and iron-stressed thermophilic cyanobacteria well documents major changes in composition of the antenna systems and in composition of the core of photosystem II. The absorption of membrane chlorophyll in particular, is blue-shifted from 679 nm in normal cells to 673 nm which is caused by absorption of chlorophyll binding protein CP 34 in stressed sample. The presence of CP 34 in the photosystem II (PS II) has also been seen in the low temperature fluorescence spectra where the increased luminescence at 685 nm has been observed. This implies the decreased efficiency of photosynthesis in iron-limited sample. We studied the energy transfer in PS II by the means of fluorescence and absorption hole-burning spectroscopy which enabled to study the influence of iron-stressed condition on energy transfer and pigment-protein interaction (Debye-Waller factor). The stressed cells exhibit the broadened spectral hole width at 682 and 685.5 nm. Abbreviations: APC, allophycocyanin; CC, cylindrical core; Chl, chlorophyll; LT, low temperature; PBS, phycobilisomes; PSB, phonon sideband; PC, phycocyanin; PR, peripheral rods; PS, photosystem; RC, reaction center, ZPH, zero phonon hole.

  20. High-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type PbTiO3 phases.

    PubMed

    Yoshiasa, Akira; Nakatani, Tomotaka; Nakatsuka, Akihiko; Okube, Maki; Sugiyama, Kazumasa; Mashimo, Tsutomu

    2016-06-01

    A high-temperature single-crystal X-ray diffraction study of a synthetic PbTiO3 perovskite was carried out over the wide temperature range 298-928 K. A transition from a tetragonal (P4mm) to a cubic (Pm \\bar 3 m) phase has been revealed near 753 K. In the non-centrosymmetric P4mm symmetry group, the difference in relative displacement between Pb and O along the c-axis is much larger than that between Ti and O. The Pb and Ti cations contribute sufficiently to polarization being shifted in the opposite direction compared with the shift of O atoms. Deviation from the linear changes in Debye-Waller factors and bonding distances in the tetragonal phases can be interpreted as a precursor phenomenon before the phase transition. Disturbance of the temperature factor Ueq for O is observed in the vicinity of the transition point, while Ueq values for Pb and Ti are continuously changing with increasing temperature. The O site includes the clear configurational disorder in the cubic phase. The polar local positional distortions remain in the cubic phase and are regarded as the cause of the paraelectricity. Estimated values of the Debye temperature ΘD for Pb and Ti are 154 and 467 K in the tetragonal phase and decrease 22% in the high-temperature phase. Effective potentials for Pb and Ti change significantly and become soft after the phase transition. PMID:27240769

  1. Local features of the crystal structure of superconducting iron chalcogenides Fe(TeSe)1 - δ

    NASA Astrophysics Data System (ADS)

    Ivanov, V. G.; Chareev, D. A.; Ivanov, A. A.; Vasil'ev, A. N.; Menushenkova, A. P.

    2016-03-01

    The local crystal structure of superconducting powders of iron chalcogenides FeTe x Se1- x ( x = 0.1, 0.22, 0.49, 0.8, 0.9) prepared by dry synthesis (without mineralizer) has been studied by EXAFS spectroscopy above the K Se and K Fe absorption edges in the temperature range of 80-300 K. The dependences of Se-Fe, Fe-Te, and Fe-Fe interatomic bond lengths and degrees of their local disordering (Debye-Waller factors) on the tellurium content and temperature have been obtained. Einstein temperatures characterizing the stiffness of each bond have been determined. The correlation of the Se-Fe bond stiffness with the dependence of the critical temperature of the superconducting transition T c on the composition of the samples under study have been established, which indicates the specific role of the Se-Fe bond in the superconducting state formation in iron chalcogenides FeTe x Se1- x .

  2. Surface Structure of Bi(111) from Helium Atom Scattering Measurements. Inelastic Close-Coupling Formalism

    PubMed Central

    2015-01-01

    Elastic and inelastic close-coupling (CC) calculations have been used to extract information about the corrugation amplitude and the surface vibrational atomic displacement by fitting to several experimental diffraction patterns. To model the three-dimensional interaction between the He atom and the Bi(111) surface under investigation, a corrugated Morse potential has been assumed. Two different types of calculations are used to obtain theoretical diffraction intensities at three surface temperatures along the two symmetry directions. Type one consists of solving the elastic CC (eCC) and attenuating the corresponding diffraction intensities by a global Debye–Waller (DW) factor. The second one, within a unitary theory, is derived from merely solving the inelastic CC (iCC) equations, where no DW factor is necessary to include. While both methods arrive at similar predictions for the peak-to-peak corrugation value, the variance of the value obtained by the iCC method is much better. Furthermore, the more extensive calculation is better suited to model the temperature induced signal asymmetries and renders the inclusion for a second Debye temperature for the diffraction peaks futile. PMID:26257838

  3. Groundwater environmental tracer data collected from the Chicot, Evangeline, and Jasper aquifers in Montgomery County and adjacent counties, Texas, 2008

    USGS Publications Warehouse

    Oden, Timothy D.

    2011-01-01

    The Gulf Coast aquifer system is the primary water supply for Montgomery County in southeastern Texas, including part of the Houston metropolitan area and the cities of Magnolia, Conroe, and The Woodlands Township, Texas. The U.S. Geological Survey, in cooperation with the Lone Star Groundwater Conservation District, collected environmental tracer data in the Gulf Coast aquifer system, primarily in Montgomery County. Forty existing groundwater wells screened in the Gulf Coast aquifer system were selected for sampling in Montgomery County (38 wells), Waller County (1 well), and Walker County (1 well). Groundwater-quality samples, physicochemical properties, and water-level data were collected once from each of the 40 wells during March-September 2008. Groundwater-quality samples were analyzed for dissolved gases and the environmental tracers sulfur hexafluoride, chlorofluorocarbons, tritium, helium-4, and helium-3/tritium. Water samples were collected and processed onsite using methods designed to minimize changes to the water-sample chemistry or contamination from the atmosphere. Replicate samples for quality assurance and quality control were collected with each environmental sample. Well-construction information and environmental tracer data for March-September 2008 are presented.

  4. Interplay between FAK, PKCδ, and p190RhoGAP in the Regulation of Endothelial Barrier Function

    PubMed Central

    Grinnell, Katie L.; Harrington, Elizabeth O.

    2011-01-01

    Disruption of either intercellular or extracellular junctions involved in maintaining endothelial barrier function can result in increased endothelial permeability. Increased endothelial permeability, in turn, allows for the unregulated movement of fluid and solutes out of the vasculature and into the surrounding connective tissue, contributing to a number of disease states, including stroke and pulmonary edema (Ermert et al., 1995; Lee and Slutsky, 2010; van Hinsbergh, 1997; Waller et al., 1996; Warboys et al., 2010). Thus, a better understanding of the molecular mechanisms by which endothelial cell junction integrity is controlled is necessary for development of therapies aimed at treating such conditions. In this review, we will discuss the functions of three signaling molecules known to be involved in regulation of endothelial permeability: focal adhesion kinase (FAK), protein kinase C delta (PKCδ), and p190RhoGAP (p190). We will discuss the independent functions of each protein, as well as the interplay that exists between them and the effects of such interactions on endothelial function. PMID:21549132

  5. Psychopathic Personality Traits and Environmental Contexts: Differential Correlates, Gender Differences, and Genetic Mediation

    PubMed Central

    Hicks, Brian M.; Carlson, Marie D.; Blonigen, Daniel M.; Patrick, Christopher J.; Iacono, William G.; MGue, Matt

    2011-01-01

    Theorists have speculated that primary psychopathy (or Factor 1 affective-interpersonal features) is prominently heritable whereas secondary psychopathy (or Factor 2 social deviance) is more environmentally determined. We tested this differential heritability hypothesis using a large adolescent twin sample. Trait-based proxies of primary and secondary psychopathic tendencies were assessed using Multidimensional Personality Questionnaire (MPQ; Tellegen & Waller, 2008) estimates of Fearless Dominance and Impulsive Antisociality, respectively (Benning et al., 2005). The environmental contexts of family, school, peers, and stressful life events were assessed using multiple raters and methods. Consistent with prior research, MPQ Impulsive Antisociality was robustly associated with each environmental risk factor, and these associations were significantly greater than those for MPQ Fearless Dominance. However, MPQ Fearless Dominance and Impulsive Antisociality exhibited similar heritability, and genetic effects mediated the associations between MPQ Impulsive Antisociality and the environmental measures. Results were largely consistent across male and female twins. We conclude that gene-environment correlations rather than main effects of genes and environments account for the differential environmental correlates of primary and secondary psychopathy. PMID:22452762

  6. Thermal properties of 1T-TaS 2 at the onset of charge density wave states

    NASA Astrophysics Data System (ADS)

    Balaguru Rayappan, John Bosco; Raj, S. Alfred Cecil; Lawrence, N.

    2010-08-01

    The crystal lattice plays an essential role in the charge density wave (CDW) phase transition together with the electron system through electron-phonon interactions. The CDW in the layered compound 1T-TaS 2 at low temperatures has a commensurate phase, which causes superlattice points to appear in the Brillouin zone of the undistorted phase. Since the effect of CDWs is to directly modulate the lattice, it is evident that an investigation that looks directly at the phonon frequencies would be most instructive in examining this phenomenon. Hence the Born-von Karman formalism, in which the equilibrium conditions are fulfilled, has been employed for the calculation of phonon frequency distribution curves of 1T-TaS 2 both in the normal and in the commensurate charge density wave (CCDW) phases. A folding technique has been adopted for the calculation in the CCDW phase. The phonon distribution and some dominant phonon frequencies for both the phases have been reported. With these results the thermal properties such as specific heat capacity, Debye Waller factor and thermal conductivity have been worked out, and are compared with the available experimental results.

  7. Development and the fragmented self: longitudinal study of dissociative symptomatology in a nonclinical sample.

    PubMed

    Ogawa, J R; Sroufe, L A; Weinfield, N S; Carlson, E A; Egeland, B

    1997-01-01

    Dissociative behaviors and their relation to both the self and self-organization were examined using the developmental psychopathology perspective in a prospective longitudinal study of high-risk children. Participants were 168 young adults (n = 79 females, n = 89 males, age = 18-19 years) considered high-risk for poor developmental outcomes at birth due to poverty. The present study investigated whether trauma, sense of self, quality of early mother-child relationship, temperament, and intelligence were related to dissociative symptomatology measured at four times across 19 years. Findings were (a) age of onset, chronicity and severity of trauma were highly correlated and predicted level of dissociation; (b) both the avoidant and disorganized patterns of attachment were strong predictors of dissociation; (c) dissociation in childhood may be a more normative response to disruption and stress, while dissociation in adolescence and young adulthood may be more indicative of psychopathology; (d) preliminary support was found for a model proposed by G. Liotti that links disorganized attachment, later trauma, and dissociation in adulthood; and (e) strong support was found for N. Waller, F. W. Putnam, and E. B. Carlson's contention that psychopathological dissociation should not be viewed as the top end of a continuum of dissociative symptomatology, but as a separate taxon that represents an extreme deviation from normal development. PMID:9449009

  8. Diffraction Studies of the Atomic Vibrations of Bulk and Surface Atoms in the Reciprocal and Real Spaces of Nanocrystalline SiC

    NASA Technical Reports Server (NTRS)

    Stelmakh, S.; Grzanka, E.; Weber, H.-P.; Vogel, S.; Palosz, B.; Palosz, B.

    2004-01-01

    To describe and evaluate the vibrational properties of nanoparticles it is necessary to distinguish between the surface and the core of the particles. Theoretical calculations show that vibrational density of states of the inner atoms of nanograins is similar to bulk material but shifted to higher energies which can be explained by the fact that the gain core is stressed (hardened) due to the presence of internal pressure. Theoretical calculations also show that there is a difference between vibrational properties of a crystal lattice of the grain interior in isolated particles and in a dense (sintered) nanocrystalline material. This is probably due to a coupling of the modes inside the grains via the grain boundaries in dense nanocrystalline bodies. We examined strains present in the surface shell based on examination of diamond and Sic nanocrystals in reciprocal (Bragg-type scattering) and real (PDF analysis) space analysis of neutron diffraction data. Recently we examined the atomic thermal motions in nanocrystalline Sic based on the assumption of a simple Einstein model for uncorrelated atomic notions. According to this model, the Bragg intensity is attenuated as a function of scattering angle by the Debye-Waller factor. Based on this assumption overall temperature factors were determined from the Wilson plots.

  9. Graphene on Ni(111): Electronic Corrugation and Dynamics from Helium Atom Scattering

    PubMed Central

    2015-01-01

    Using helium atom scattering, we have studied the structure and dynamics of a graphene layer prepared in situ on a Ni(111) surface. Graphene/Ni(111) exhibits a helium reflectivity of ∼20% for a thermal helium atom beam and a particularly small surface electron density corrugation ((0.06 ± 0.02) Å peak to peak height). The Debye–Waller attenuation of the elastic diffraction peaks of graphene/Ni(111) and Ni(111) was measured at surface temperatures between 150 and 740 K. A surface Debye temperature of θD = (784 ± 14) K is determined for the graphene/Ni(111) system and θD = (388 ± 7) K for Ni(111), suggesting that the interlayer interaction between graphene and the Ni substrate is intermediary between those for strongly interacting systems like graphene/Ru(0001) and weakly interacting systems like graphene/Pt(111). In addition we present measurements of low frequency surface phonon modes on graphene/Ni(111) where the phonon modes of the Ni(111) substrate can be clearly observed. The similarity of these findings with the graphene/Ru(0001) system indicates that the bonding of graphene to a metal substrate alters the dynamic properties of the graphene surface strongly and is responsible for the high helium reflectivity of these systems. PMID:26617683

  10. Structures of Plutonium(IV) and Uranium(VI) with N,N-Dialkyl Amides from Crystallography, X-ray Absorption Spectra, and Theoretical Calculations.

    PubMed

    Acher, Eléonor; Hacene Cherkaski, Yanis; Dumas, Thomas; Tamain, Christelle; Guillaumont, Dominique; Boubals, Nathalie; Javierre, Guilhem; Hennig, Christoph; Solari, Pier Lorenzo; Charbonnel, Marie-Christine

    2016-06-01

    The structures of plutonium(IV) and uranium(VI) ions with a series of N,N-dialkyl amides ligands with linear and branched alkyl chains were elucidated from single-crystal X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), and theoretical calculations. In the field of nuclear fuel reprocessing, N,N-dialkyl amides are alternative organic ligands to achieve the separation of uranium(VI) and plutonium(IV) from highly concentrated nitric acid solution. EXAFS analysis combined with XRD shows that the coordination structure of U(VI) is identical in the solution and in the solid state and is independent of the alkyl chain: two amide ligands and four bidentate nitrate ions coordinate the uranyl ion. With linear alkyl chain amides, Pu(IV) also adopt identical structures in the solid state and in solution with two amides and four bidentate nitrate ions. With branched alkyl chain amides, the coordination structure of Pu(IV) was more difficult to establish unambiguously from EXAFS. Density functional theory (DFT) calculations were consequently performed on a series of structures with different coordination modes. Structural parameters and Debye-Waller factors derived from the DFT calculations were used to compute EXAFS spectra without using fitting parameters. By using this methodology, it was possible to show that the branched alkyl chain amides form partly outer-sphere complexes with protonated ligands hydrogen bonded to nitrate ions. PMID:27171842

  11. [Traumatic nerve damage: causes, approaches and prognosis].

    PubMed

    Müller-Vahl, H

    2015-02-01

    Whereas minor injuries to peripheral nerves merely lead to a circumscribed damage of the myelin sheath which is completely healed within 3 months, penetrating injuries lead to degeneration of the distal axonal fragment (Waller degeneration) and simultaneously to time-dependent alterations in the effector organs, in the perikarya in the medulla and spinal ganglia as well as in the brain. Animal experimental studies and also findings in humans confirm that the conditions for regeneration of nerve fibers are most favorable in the first days and weeks following injury. Therefore, for optimal therapy it should be clarified as early as possible whether there is a chance for reinnervation using exclusively conservative therapy or whether an operative reconstruction is necessary due to the severity of structural damage. Imaging investigation procedures, such as neurosonography and magnetic resonance (MR) neurography can provide decisive information on this aspect. As a rule, the decision on the indications for a nerve operation should be made within the first 3 months. Even with optimal therapy the healing process of severe neural injuries is often unsatisfactory. For some years novel procedures for improvement of nerve regeneration have been tested in animal experiments which involve totally different points in the healing process. It is hoped that with these approaches procedures for improvement in the treatment of nerve injuries in humans can be developed in the near future. PMID:25627807

  12. Conversion of amorphous calcium phosphate into hydroxyapatite investigated by EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Harries, J. E.; Hukins, D. W. L.; Holt, C.; Hasnain, S. S.

    1987-10-01

    Amorphous calcium phosphate (ACP) was precipitated from solution at pH 10. Some samples were allowed to transform to poorly crystalline hydroxyapatite (HAP), at this pH, for periods up to 120 h. All samples were stabilised by freeze-drying and characterised by extended X-ray absorption fine structure (EXAFS) spectroscopy as well as by chemical analysis, infra-red spectroscopy and X-ray powder diffraction. EXAFS spectra, recorded above the K absorption edge of Ca, were interpreted using a model developed previously to explain the features of the EXAFS spectrum of fully crystalline HAP. Eight shells of atoms surrounding Ca out to 0.57 nm were required to explain the appearance of poorly crystalline HAP. In contrast, only the innermost three of these shells were required to interpret the spectrum of the initial ACP. Moreover, these three shells had almost identical radii and Debye-Waller factors as in the poorly crystalline HAP and so the process of crystallisation involves only the development of longer-range order without changing the immediate environment of Ca.

  13. The statistics of the thermal motion of the atoms during imaging process in transmission electron microscopy and related techniques.

    PubMed

    Rother, Axel; Gemming, Thomas; Lichte, Hannes

    2009-01-01

    The concern of this work is the influence of the thermal motion of the atoms on electron scattering simulations, used for quantitative interpretation of results in high-resolution electron microscopy. We distinguish between the influence of inelastic phonon excitation and the effect of a moving lattice on images generated by elastically scattered electrons. It is shown that, analog to aberrations, the impact of a moving lattice differs substantially with respect to different imaging conditions and cannot be described by the Debye-Waller damping applicable in XRD. We derive a new formalism, based on the frozen lattice and multislice approach, to incorporate the statistics of the thermal motion into elastic TEM imaging simulations, taking into account different imaging conditions. The averaging over different atom positions is generally performed within a density matrix framework, which can be linearized in the special case of off-axis electron holography. All findings are supported by explicit numerical simulations: molecular dynamics simulations are performed to get a realistic thermal motion and the electron scattering simulations are performed within the new multislice algorithm. PMID:19027234

  14. Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X  =  S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Caramazza, S.; Marini, C.; Simonelli, L.; Dore, P.; Postorino, P.

    2016-08-01

    The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo–X, Mo–Mo and X–X (X  =  S, Se, and Te) and of the corresponding Debye–Waller factors have been extracted over the 70–500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo–X and X–X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo–X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2.

  15. Quantitative x-ray diffraction analysis of bimodal damage distributions in Tm implanted Al0.15Ga0.85N

    NASA Astrophysics Data System (ADS)

    Magalhães, S.; Fialho, M.; Peres, M.; Lorenz, K.; Alves, E.

    2016-04-01

    In this work radial symmetric x-ray diffraction scans of Al0.15Ga0.85N thin films implanted with Tm ions were measured to determine the lattice deformation and crystal quality as functions of depth. The alloys were implanted with 300 keV Tm with 10° off-set to the sample normal to avoid channelling, with fluences varying between 1013 Tm cm-2 and 5  ×  1015 Tm cm-2. Simulations of the radial 2θ-ω scans were performed under the frame of the dynamical theory of x-ray diffraction assuming Gaussian distributions of the lattice strain induced by implantation defects. The structure factor of the individual layers is multiplied by a static Debye-Waller factor in order to take into account the effect of lattice disorder due to implantation. For higher fluences two asymmetric Gaussians are required to describe well the experimental diffractograms, although a single asymmetric Gaussian profile for the deformation is found in the sample implanted with 1013 Tm cm-2. After thermal treatment at 1200 °C, the crystal quality partially recovers as seen in a reduction of the amplitude of the deformation maximum as well as the total thickness of the deformed layer. Furthermore, no evidence of changes with respect to the virgin crystal mosaicity is found after implantation and annealing.

  16. [On the first studies of electrophysiology].

    PubMed

    de Micheli, Alfredo

    2011-01-01

    A historical outline of the evolution of electrophysiology from the eighteenth century is shortly presented. Topics concerning the so called animal electricity starting from the observations on descharges of Torpedo fish until Bolognese Galvani's researches on the frogs are exposed. The points of view of their oppositionists also are examined. These ones, leaded by the physicist Alessandro Volta, professor in the University of Pavia, believed that electricity detected by galvanists was not inherent to animal but was due to the action of the metallic conductors present in the circuit: contact electricity. Only towards the middle of the nineteenth century the physicist Carlo Matteucci attained to demonstrate the existente of the real animal electricity in form of injury current. It was possible to determine that quantitatively thanks to the capillary electrometer built in 1872 by the French physicist Gabriel Lippmann. This instrument was used by the English physiologist Waller in order to obtain the primitive electrocardiographic tracings in humans (1887). At beginnings of the twentieth century, the Dutch professor Willem Einthoven, of the University of Leiden, introduced his string galvanometer which permitted to allow the modern electrocardiography. So it was possible to record the electrical potentials of myocardial cells, first in vitro, later in isolated and perfused heart, son after in dog's heart in situ and finally in human heart. Therefore now it is possible to effectuate endocardial and epicardial mappings, indispensable in order to diagnose and treat the cardiac arrhythmias. PMID:22188891

  17. Emergence: A Planetarium and Art Gallery Collaboration Between Artist, Astronomer, and Musician

    NASA Astrophysics Data System (ADS)

    Beaver, J.; Waller, J. B.; Turner, M.

    2011-09-01

    We describe an unusual planetarium program and art gallery exhibition that premiered in Menasha, Wisconsin. Emergence combines fine art and improvisational music with astronomy and physics. The authors, Judith Baker Waller, John Beaver, and Matt Turner, are, respectively, artist, astronomer, and musician. All three acted as partners in planning and executing the final production. The overall goal of Emergence is to use art, music, and natural science each as a point of departure to learn about the others, and to explore the interaction between humans and the natural world and the differences and commonalities between art, science, and music. Of particular interest, the planetarium portion includes techniques that are, so far as we know, unique. Each night the show is different, the details chosen randomly, but always according to the same theoretical scheme. Various elements are parameterized, the show varying with time according to subroutines that dictate the overall pacing and look, but with details always chosen randomly according to prearranged probabilities. We believe that some of these techniques could be of interest to others who wish to explore the unique possibilities of the planetarium as educational performance space. We argue that this provides a useful format for collaborations between artist and scientist, as scientific content can be delivered in a way that is consistent with the concerns of the artist. We describe some of the approaches taken toward these ends in Emergence, and some of the lessons learned about the process of collaboration between a scientist, a visual artist and a performing artist.

  18. [The historical bases of a super-specialty: electrocardiography].

    PubMed

    Gensini, Gian Franco; Conti, Andrea A; Lippi, Donatella; Conti, Antonio

    2004-01-01

    In the XVIII century the first structured experiments in the field of bioelectricity were performed, and the Italian scientist Luigi Galvani documented the muscular contraction of a frog undergoing an electric shock. In 1791 he showed that the electric stimulation of the heart of a frog determined the contraction of the heart itself. In the first thirty years of the XIX century galvanometers were developed, and in 1842-42 Carlo Matteucci documented that electric activity was present even in the cardiac muscle at rest. At the end of the XIX century Augustus Waller was among the first scientists to publish an electrocardiographic recording obtained from the human body surface; most of his contemporaneous, however, did not retain that electrocardiography might have been an effective clinical application. Willem Einthoven, instead, was convinced of the widespread feasibility of clinical electrocardiography, and promoted a number of improvements and refinements in electrocardiographic technique. The most important and diagnostic-technical development of electrocardiography occurred in the second half of the XX century, and still today, even if many different sophisticated instrumental examinations are available for cardiologic evaluation, electrocardiography represents an essential first-line diagnostic tool in clinical cardiology. PMID:16259095

  19. Structural arrest transitions in fluids described by two Yukawa potentials

    NASA Astrophysics Data System (ADS)

    Wu, Jianlan; Liu, Yun; Chen, Wei-Ren; Cao, Jianshu; Chen, Sow-Hsin

    2004-11-01

    We study a model colloidal system where particles interact via short-range attractive and long-range repulsive Yukawa potentials. Using the structure factor calculated from the mean-spherical approximation as the input, the kinetic phase diagrams as functions of the attraction depth and the volume fraction are obtained by calculating the Debye-Waller factors in the framework of the mode-coupling theory for three different heights of the repulsive barrier. The glass-glass reentrance phenomenon in the attractive colloidal case is also observed in the presence of the long-range repulsive barrier, which results in the lower and upper glass regimes. Competition between the short-range attraction and the long-range repulsion gives rise to new regimes associated with clusters such as “static cluster glass” and “dynamic cluster glass,” which appear in the lower glass regime. Along the liquid-glass transition line between the liquid regime and the lower glass regime, crossover points separating different glass states are identified.

  20. Line Edge Roughness and Cross Sectional Characterization of Sub-50 nm Structures Using Critical Dimension Small Angle X-ray Scattering

    SciTech Connect

    Wang Chengqing; Jones, Ronald L.; Lin, Eric K.; Wu Wenli; Ho, Derek L.; Villarrubia, John S.; Choi, Kwang-Woo; Clarke, James S.; Roberts, Jeanette; Bristol, Robert; Bunday, Benjamin

    2007-09-26

    The need to characterize line edge and line width roughness in patterns with sub-50 nm critical dimensions challenges existing platforms based on electron microscopy and optical scatterometry. The development of x-ray based metrology platforms provides a potential route to characterize a variety of parameters related to line edge roughness by analyzing the diffracted intensity from a periodic array of test patterns. In this study, data from a series of photoresist line/space patterns featuring programmed line width roughness are measured by critical dimension small angle x-ray scattering (CD-SAXS). For samples with designed periodic roughness, CD-SAXS provides the wavelength and amplitude of the periodic roughness through satellite diffraction peaks. For real world applications, the rate of decay of intensity, termed an effective 'Debye-Waller' factor in CD-SAXS, provides an overall measure of the defects of the patterns. CD-SAXS data are compared to values obtained from critical dimension scanning electron microscopy (CD-SEM). Correlations between the techniques exist, however significant differences are observed for the current samples. A tapered cross sectional profile provides a likely explanation for the observed differences between CD-SEM and CD-SAXS measurements.

  1. High-resolution Valence and Core Excitation Spectra via First-Principles Calculations and Experiment

    NASA Astrophysics Data System (ADS)

    Shirley, Eric; Fossard, F.; Gilmore, K.; Hug, G.; Kas, J. J.; Rehr, J. J.; Vila, F.

    We calculate the optical and C K-edge near edge spectra of crystalline and molecular C60 measured with high-resolution electron energy-loss spectroscopy. The calculations are carried out using at least three different methods: Bethe-Salpeter calculations using the NIST Bethe-Salpeter Equation solver (NBSE) in the valence and OCEAN (Obtaining Core Excitation with Ab initio methods and NBSE) suite [Gilmore et al., Comp. Phys. Comm., (2015)]; excited-core-hole calculations using XCH [D. Prendergast and G. Galli, Phys. Rev. Lett. 96, 215502 (2006)]; and constrained occupancy using StoBe (Stockholm-Berlin core-excitation code) [StoBe-deMon version 3.0, K. Hermann et al. (2009)]. They include self-energy effects, lifetime-damping, and Debye-Waller effects. A comparison of spectral features to those observed illustrates the sensitivity of certain features to computation details (e.g., self-energy corrections and core-hole screening). This may point to limitations of various approximations, e.g. in conventional BSE paradigm and/or the incomplete treatment of vibrational effects. Supported in part by DOE BES Grant DE-FG03-97ER45623 (JJR, JJK, FV).

  2. Localization model description of diffusion and structural relaxation in glass-forming Cu–Zr alloys

    NASA Astrophysics Data System (ADS)

    Douglas, Jack F.; Pazmino Betancourt, Beatriz A.; Tong, Xuhang; Zhang, Hao

    2016-05-01

    We test the localization model (LM) prediction of a parameter-free relationship between the α-structural relaxation time τ α and the Debye–Waller factor    for a series of simulated glass-forming Cu–Zr metallic liquids having a range of alloy compositions. After validating this relationship between the picosecond (‘fast’) and long-time relaxation dynamics over the full range of temperatures and alloy compositions investigated in our simulations, we show that it is also possible to estimate the self-diffusion coefficients of the individual atomic species (D Cu, D Zr) and the average diffusion coefficient D using the LM, in conjunction with the empirical fractional Stokes–Einstein (FSE) relation linking these diffusion coefficients to τ α . We further observe that the fragility and extent of decoupling between D and τ α strongly correlate with    at the onset temperature of glass-formation T A where particle caging and the breakdown of Arrhenius relaxation first emerge.

  3. Anomalous structural behavior in the metamagnetic transition of FeRh thin films from a local viewpoint

    NASA Astrophysics Data System (ADS)

    Wakisaka, Yuki; Uemura, Yohei; Yokoyama, Toshihiko; Asakura, Hiroyuki; Morimoto, Hiroyuki; Tabuchi, Masao; Ohshima, Daiki; Kato, Takeshi; Iwata, Satoshi

    2015-11-01

    The metamagnetic transition in FeRh thin films has been investigated via temperature-dependent x-ray-absorption fine-structure spectroscopy in order to gain correlations between magnetization and local electronic and geometric structures. According to the Fe and Rh K -edge x-ray-absorption near-edge structure (XANES), strong hybridization between Fe and Rh was revealed to exist. This Fe-Rh hybridization was observed to decrease during the phase transition from the antiferromagnetic (AFM) to ferromagnetic (FM) phases from the systematic change in the Fe K -edge XANES. In addition, only the Debye-Waller factor of the Fe-Fe pair in the AFM phase was observed to be considerably enhanced when compared with that in the FM phase, which was ascribed to local structural fluctuation inherent in the AFM phase. By considering the different features of the exchange interactions in Fe-Rh and Fe-Fe, this anomalous behavior is interpreted as being consistent with the recent theoretical study proposing the local fluctuations of spin and structure. Therefore, we consider that the local spin and Fe-Fe distance fluctuations play an important role in driving the metamagnetic transition, whereas the Fe-Rh hybridization correlates with the static stability of each magnetic phase.

  4. Theoretical calculations of X-ray absorption spectra of a copper mixed ligand complex using computer code FEFF9

    NASA Astrophysics Data System (ADS)

    Gaur, A.; Shrivastava, B. D.

    2014-09-01

    The terms X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) refer, respectively, to the structure in the X-ray absorption spectrum at low and high energies relative to the absorption edge. Routine analysis of EXAFS experiments generally makes use of simplified models and several many-body parameters, e.g. mean free paths, many-body amplitude factors, and Debye-Waller factors, as incorporated in EXAFS analysis software packages like IFEFFIT which includes Artemis. Similar considerations apply to XANES, where the agreement between theory and experiment is often less satisfactory. The recently available computer code FEFF9 uses the real-space Green's function (RSGF) approach to calculate dielectric response over a broad spectrum including the dominant low-energy region. This code includes improved treatments of many-body effects such as inelastic losses, core-hole effects, vibrational amplitudes, and the extension to full spectrum calculations of optical constants including solid state effects. In the present work, using FEFF9, we have calculated the X-ray absorption spectrum at the K-edge of copper in a complex, viz., aqua (diethylenetriamine) (isonicotinato) copper(II), the crystal structure of which is unknown. The theoretical spectrum has been compared with the experimental spectrum, recorded by us at the XAFS beamline 11.1 at ELETTRA synchrotron source, Italy, in both XANES and EXAFS regions.

  5. Conformational substates in a protein: structure and dynamics of metmyoglobin at 80 K.

    PubMed

    Hartmann, H; Parak, F; Steigemann, W; Petsko, G A; Ponzi, D R; Frauenfelder, H

    1982-08-01

    The crystal structure of sperm whale metmyoglobin has been determined at 80 K to a resolution of 2A. The overall structure at 80 K is similar to that at 300 K except that the volume is smaller. Refinement of the structure by the method of restrained least squares (current R = 0.175) permits the assignment of isotropic atomic mean-square displacements to all nonhydrogen atoms. Comparison with the values obtained earlier at 250-300 K indicates that the protein at 80 K is more rigid. The average experimentally determined Debye-Waller factor, B, for the protein is 14A2 at 300 K and 5A2 at 80 K. Plots of backbone mean-square displacement vs. temperature show a discontinuity of slope for at least one-third of all residues. This behavior is in good agreement with the temperature dependence of the mean-square displacement of the heme iron as measured by Mössbauer absorption. The magnitudes of the smallest mean-square displacements observed at 80 K indicate that intramolecular motions can be frozen out to a surprisingly large degree. Even at 80 K, however, some atoms in myoglobin still have mean-square displacements greater than 0.1A2, thus providing evidence for conformational substates. PMID:6956905

  6. Commensurability and stability in nonperiodic systems

    PubMed Central

    Fasano, Y.; De Seta, M.; Menghini, M.; Pastoriza, H.; de la Cruz, F.

    2005-01-01

    We have investigated the response of 3D Bi2Sr2CaCu2O8 vortex structures to a weak perturbation induced by 2D Fe pinning structures acting on one extremity of vortex lines. The pinning patterns were nano-engineered at the sample surface by means of either a Bitter decoration of the vortex lattice or electron-beam lithography. The commensurability conditions between 2D rigid pinning potentials and 3D elastic structures with short-range positional and long-range orientational correlation have been experimentally determined. When the 2D potential is a replica of the nonperiodic vortex structure an amplification of its interaction with the vortex structure takes place. This effect is detected only for the first matching field, becoming negligible for other matching fields. On the other hand, a periodic 2D perturbation is shown to transform the nonperiodic Bragg glass-like structure into an Abrikosov crystal with an effective Debye–Waller factor. PMID:16576763

  7. Estimating continental hydrology parameters from existing space missions: the need for a dedicated surface water mission

    NASA Astrophysics Data System (ADS)

    Mognard, N. M.; Cazenave, A.; Alsdorf, D. E.; Rodriguez, E.

    2006-12-01

    Different instruments on board Earth observing satellite missions that were designed either for ocean missions or land surface classification have been used to retrieve continental surface hydrology parameters. Conventional altimeter profilers that have been designed for measuring the ocean surface topography provide limited use for surface hydrology. Analysis of conventional altimeter time series over lakes and rivers clearly indicates superimposed seasonal and interannual variabilities while the synergy of altimeter water height estimate with the water extent provided by radiometers is a means of estimating water volume variations. The synergy with the GRACE gravimetry mission, which estimates the variations of the integrated water mass, can provide estimates of the underground water mass variability. However, profiling altimetric methods of measuring water surface elevations and their changes are incapable of capturing the inherent dynamics of all continental surface waters. For example, using a profiling altimeter and a 16-day orbital repeat cycle, like that of Terra, misses about 30 percent of the rivers and 70 percent of the lakes in the global data bases. An international team is proposing the Water Elevation Recovery mission (WatER), a high-resolution, image- based approach with two-dimensional acquisitions of water surface elevations h, dh/dt, and dh/dx required to answer important hydrologic questions. A key technology of the WatER mission is a Ka-band Radar INterferometer (KaRIN) which is a near-nadir viewing, 120 km wideswath based instrument that uses interferometric SAR processing of the returned pulses to yield single-look 5m azimuth and 10m to 70m range resolution, with an elevation accuracy of approximately 50 cm. Polynomial based averaging of heights along the water body increases the height accuracy to about 3 cm. The entire globe is covered twice every 16 days and orbit subcycles allow the average visit to be about half this time at low to mid

  8. WatER: The proposed Water Elevation Recovery satellite mission

    NASA Astrophysics Data System (ADS)

    Alsdorf, D.; Mognard, N.; Rodriguez, E.; Participants, W.

    2005-12-01

    Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial and temporal dynamics of surface water storage and discharge globally. The core mission objective is to describe and understand the continental water cycle and the hydrological processes (e.g., floodplain hydraulics) at work in a river basin. The key question that will be answered by WatER is: "Where is water stored on Earth's land surfaces, and how does this storage vary in space and time?" WatER will facilitate societal needs by (1) improving our understanding of flood hazards; (2) freely providing water volume information to countries who critically rely on rivers that cross political borders; and (3) mapping the variations in water bodies that contribute to disease vectors (e.g., malaria). Conventional altimeter profiles are, without question, incapable of supplying the measurements needed to address scientific and societal questions. WatER will repeatedly measure the spatially distributed water surface elevations (h) of wetlands, rivers, lakes, reservoirs, etc. Successive h measurements yield dh/dt, (t is time), hence a volumetric change in water stored or lost. Individual images of h yield dh/dx (x is distance), hence surface water slope, which is necessary for estimating streamflow. WatER's main instrument is a Ka-band radar interferometer (KaRIN) which is the only technology capable of supplying the required imaging capability of h. KaRIN has a rich heritage based on (1) the many highly successful ocean observing radar altimeters, (2) the Shuttle Radar Topography Mission (SRTM), and (3) the development effort of the Wide Swath Ocean Altimeter (WSOA). The interferometric altimeter is a near-nadir viewing, 120 km wideswath based instrument that uses interferometric SAR processing of the returned pulses to yield single-look 5m azimuth and 10m to 70m range resolution, with an elevation accuracy of approximately 50 cm. Polynomial based averaging of heights along the

  9. NASA Tech Briefs, December 2011

    NASA Technical Reports Server (NTRS)

    2011-01-01

    Topics covered include: 1) SNE Industrial Fieldbus Interface; 2) Composite Thermal Switch; 3) XMOS XC-2 Development Board for Mechanical Control and Data Collection; 4) Receiver Gain Modulation Circuit; 5) NEXUS Scalable and Distributed Next-Generation Avionics Bus for Space Missions; 6) Digital Interface Board to Control Phase and Amplitude of Four Channels; 7) CoNNeCT Baseband Processor Module; 8) Cryogenic 160-GHz MMIC Heterodyne Receiver Module; 9) Ka-Band, Multi-Gigabit-Per-Second Transceiver; 10) All-Solid-State 2.45-to-2.78-THz Source; 11) Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn); 12) Space Environments Testbed; 13) High-Performance 3D Articulated Robot Display; 14) Athena; 15) In Situ Surface Characterization; 16) Ndarts; 17) Cryo-Etched Black Silicon for Use as Optical Black; 18) Advanced CO2 Removal and Reduction System; 19) Correcting Thermal Deformations in an Active Composite Reflector; 20) Umbilical Deployment Device; 21) Space Mirror Alignment System; 22) Thermionic Power Cell To Harness Heat Energies for Geothermal Applications; 23) Graph Theory Roots of Spatial Operators for Kinematics and Dynamics; 24) Spacesuit Soft Upper Torso Sizing Systems; 25) Radiation Protection Using Single-Wall Carbon Nanotube Derivatives; 26) PMA-PhyloChip DNA Microarray to Elucidate Viable Microbial Community Structure; 27) Lidar Luminance Quantizer; 28) Distributed Capacitive Sensor for Sample Mass Measurement; 29) Base Flow Model Validation; 30) Minimum Landing Error Powered-Descent Guidance for Planetary Missions; 31) Framework for Integrating Science Data Processing Algorithms Into Process Control Systems; 32) Time Synchronization and Distribution Mechanisms for Space Networks; 33) Local Estimators for Spacecraft Formation Flying; 34) Software-Defined Radio for Space-to-Space Communications; 35) Reflective Occultation Mask for Evaluation of Occulter Designs for Planet Finding; and 36) Molecular Adsorber Coating

  10. Size and Age Dependence of Koronis Family Colors

    NASA Astrophysics Data System (ADS)

    Molnar, L. A.

    2011-10-01

    The ancient and massive Koronis family now has four identified subfamilies (asteroid families made by the breakup of fragments of the ancient collision), with ages running from 5.7 to 290 My. This presents unique opportunities to explore space weathering processes, along with dynamical processes such as collisions and binary formation and destruction. Analysis of family members with accurate SDSS measurements shows a correlation of average subfamily color with age that for the first time is highly statistically significant. Yet Thomas et al. (2011) report a size dependence of the colors of the ancient family that demands caution when comparing subfamilies with differing size distributions. Reanalyis of the Thomas et al. data show the reported break near asteroid diameter 5 km is not significant. However, analysis of the much more extensive SDSS data set show a significant break past diameter 2.5 km, with smaller objects systematically bluer. The break is not present in the Karin subfamily (the youngest at 5.7 My), but is already fully developed in the Eriphyla subfamily (only 220 My). The reddening trend with age remains even when comparing only asteroids of similar size, confirming the presence of space weathering phenomena. The meaning of the trend with size is not immediately clear. We consider briefly the strengths and weaknesses of several interpretations of the bluer colors for small objects: 1) those objects receive more jolts from random collisions capable of shaking the regolith and exposing fresh material beneath; 2) those objects receive more jolts from the cycle of fission and recombination driven by YORP; and 3) the lower gravity on those objects retains regolith less well.

  11. Lunar and Planetary Science XXXVI, Part 18

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Topics discussed include: PoDS: A Powder Delivery System for Mars In-Situ Organic, Mineralogic and Isotopic Analysis Instruments Planetary Differentiation of Accreting Planetesimals with 26Al and 60Fe as the Heat Sources Ground-based Observation of Lunar Surface by Lunar VIS/NIR Spectral Imager Mt. Oikeyama Structure: First Impact Structure in Japan? Central Mounds in Martian Impact Craters: Assessment as Possible Perennial Permafrost Mounds (Pingos) A Further Analysis of Potential Photosynthetic Life on Mars New Insight into Valleys-Ocean Boundary on Mars Using 128 Pixels per Degree MOLA Data: Implication for Martian Ocean and Global Climate Change; Recursive Topography Based Surface Age Computations for Mars: New Insight into Surficial Processes That Influenced Craters Distribution as a Step Toward the Formal Proof of Martian Ocean Recession, Timing and Probability; Laser-induced Breakdown Spectroscopy: A New Method for Stand-Off Quantitative Analysis of Samples on Mars; Milk Spring Channels Provide Further Evidence of Oceanic, >1.7-km-Deep Late Devonian Alamo Crater, Southern Nevada; Exploration of Martian Polar Residual Caps from HEND/ODYSSEY Data; Outflow Channels Influencing Martian Climate: Global Circulation Model Simulations with Emplaced Water; Presence of Nonmethane Hydrocarbons on Pluto; Difference in Degree of Space Weathering on the Newborn Asteroid Karin; Circular Collapsed Features Related to the Chaotic Terrain Formation on Mars; A Search for Live (sup 244)Pu in Deep-Sea Sediments: Preliminary Results of Method Development; Some Peculiarities of Quartz, Biotite and Garnet Transformation in Conditions of Step-like Shock Compression of Crystal Slate; Error Analysis of Remotely-Acquired Mossbauer Spectra; Cloud Activity on Titan During the Cassini Mission; Solar Radiation Pressure and Transient Flows on Asteroid Surfaces; Landing Site Characteristics for Europa 1: Topography; and The Crop Circles of Europa.

  12. Multiverse: Increasing Diversity in Earth and Space Science Through Multicultural Education

    NASA Astrophysics Data System (ADS)

    Peticolas, L. M.; Raftery, C. L.; Mendez, B.; Paglierani, R.; Ali, N. A.; Zevin, D.; Frappier, R.; Hauck, K.; Shackelford, R. L., III; Yan, D.; Thrall, L.

    2015-12-01

    Multiverse at the University of California, Berkeley Space Sciences Laboratory provides earth and space science educational opportunities and resources for a variety of audiences, especially for those who are underrepresented in the sciences. By way of carefully crafted space and earth science educational opportunities and resources, we seek to connect with people's sense of wonder and facilitate making personal ties to science and the learning process in order to, ultimately, bring the richness of diversity to science and make science discovery accessible for all. Our audiences include teachers, students, education and outreach professionals, and the public. We partner with NASA, the National Science Foundation, scientists, teachers, science center and museum educators, park interpreters, and others with expertise in reaching particular audiences. With these partners, we develop resources and communities of practice, offer educator workshops, and run events for the public. We will will present on our pedagogical techniques, our metrics for success, and our evaluation findings of our education and outreach projects that help us towards reaching our vision: We envision a world filled with science literate societies capable of thriving with today's technology, while maintaining a sustainable balance with the natural world; a world where people develop and sustain the ability to think critically using observation and evidence and participate authentically in scientific endeavors; a world where people see themselves and their culture within the scientific enterprise, and understand science within the context that we are all under one sky and on one Earth. Photo Caption: Multiverse Team Members at our Space Sciences Laboratory from left to right: Leitha Thrall, Daniel Zevin, Bryan Mendez, Nancy Ali, Igor Ruderman, Laura Peticolas, Ruth Paglierani, Renee Frappier, Rikki Shackelford, Claire Raftery, Karin Hauck, and Darlene Yan.

  13. Well-ordered science and Indian epistemic cultures: toward a polycentered history of science.

    PubMed

    Ganeri, Jonardon

    2013-06-01

    This essay defends the view that "modern science," as with modernity in general, is a polycentered phenomenon, something that appears in different forms at different times and places. It begins with two ideas about the nature of rational scientific inquiry: Karin Knorr Cetina's idea of "epistemic cultures," and Philip Kitcher's idea of science as "a system of public knowledge," such knowledge as would be deemed worthwhile by an ideal conversation among the whole public under conditions of mutual engagement. This account of the nature of scientific practice provides us with a new perspective from which to understand key elements in the philosophical project of Jaina logicians in the seventh, eighth, and ninth centuries C.E. Jaina theory seems exceptionally well targeted onto two of the key constituents in the ideal conversation--the classification of all human points of view and the representation of end states of the deliberative process. The Buddhist theory of the Kathāvatthu contributes to Indian epistemic culture in a different way: by supplying a detailed theory of how human dialogical standpoints can be revised in the ideal conversation, an account of the phenomenon Kitcher labels "tutoring." Thus science in India has its own history, one that should be studied in comparison and contrast with the history of science in Europe. In answer to Joseph Needham, it was not 'modern science' which failed to develop in India or China but rather non-well-ordered science, science as unconstrained by social value and democratic consent. What I argue is that this is not a deficit in the civilisational histories of these countries, but a virtue. PMID:23961693

  14. 2012 Aspen Winter Conference New Paradigms for Low-Dimensional Electronic Materials, February 5-10, 2012

    SciTech Connect

    Moore, Joel; Rabe, Karin; Nayak, Chetan; Troyer, Matthias

    2012-05-01

    Aspen Center for Physics Project Summary DOE Budget Period: 10/1/2011 to 9/30/2012 Contract # DE-SC0007479 New Paradigms for Low-Dimensional Electronic Materials The 2012 Aspen Winter Conference on Condensed Matter Physics was held at the Aspen Center for Physics from February 5 to 10, 2012. Seventy-four participants from seven countries, and several universities and national labs attended the workshop titled, New Paradigms for Low-Dimensional Electronic Materials. There were 34 formal talks, and a number of informal discussions held during the week. Talks covered a variety of topics related to DOE BES priorities, including, for example, advanced photon techniques (Hasan, Abbamonte, Orenstein, Shen, Ghosh) and predictive theoretical modeling of materials properties (Rappe, Pickett, Balents, Zhang, Vanderbilt); the full conference schedule is provided with this report. The week's events included a public lecture (Quantum Matters given by Chetan Nayak from Microsoft Research) and attended by 234 members of the public, and a physics caf© geared for high schoolers that is a discussion with physicists conducted by Kathryn Moler (Stanford University) and Andrew M. Rappe (University of Pennsylvania) and attended by 67 locals and visitors. While there were no published proceedings, some of the talks are posted online and can be Googled. The workshop was organized by Joel Moore (University of California Berkeley), Chetan Nayak (Microsoft Research), Karin Rabe (Rutgers University), and Matthias Troyer (ETH Zurich). Two organizers who did not attend the conference were Gabriel Aeppli (University College London & London Centre for Nanotechnology) and Andrea Cavalleri (Oxford University & Max Planck Hamburg).

  15. Dislocation dynamics, plasticity and avalanche statistics using the phase-field crystal model

    NASA Astrophysics Data System (ADS)

    Angheluta, Luiza

    2013-03-01

    The plastic deformation of stressed crystalline materials is characterized by intermittency and scaling behavior. The sudden strain bursts arise from collective interactions between depinned crystal defects such as dislocations. Recent experiments on sheared nanocrystals provide insights into the connection between the crystal plasticity and the mean field theory of the depinning transition, based on the similar power-law statistics of avalanche events. However, a complete theoretical formulation of this connection is still lacking, as are high quality numerical data. Phase field crystal modelling provides an efficient numerical approach to simulating the dynamics of dislocations in plastic flows at finite temperature. Dislocations are naturally created as defects in a periodic ground state that is being sheared, without any ad hoc creation and annihilation rules. These crystal defects interact and annihilate with one another, generating a collective effect of avalanches in the global plastic strain rate. We examine the statistics of plastic avalanches both at finite and zero temperatures, and find good agreement with the predictions of the mean field interface depinning theory. Moreover, we predict universal scaling forms for the extreme statistics of avalanches and universal relations between the power-law exponents of avalanche duration, size and extreme value. These results account for the observed power-law distribution of the maximum amplitudes in acoustic emission experiments of crystal plasticity, but are also broadly applicable to other systems in the mean-field interface depinning universality class, ranging from magnets to earthquakes. The work reported here was performed in collaboration with: Georgios Tsekenis, Michael LeBlanc, Patrick Y Chan, Jon Dantzig, Karin Dahmen, and Nigel Goldenfeld. The work was supported by the Center for Physics of Geological Processes (Norway) through a post-doctoral grant, the National Science Foundation through grant NSF

  16. Assimilation of wide swath altimetry to improve modelling of the Ob river, in western Siberia

    NASA Astrophysics Data System (ADS)

    Biancamaria, Sylvain; Durand, Michael; Andreadis, Kostas; Bates, Paul; Boone, Aaron; Mognard, Nelly; Rodriguez, Ernesto; Alsdorf, Doug; Lettenmaier, Dennis

    2010-05-01

    Variations in the hydrologic cycle of Arctic rivers, due to climate change, have far-reaching consequences on the global water and carbon cycles, as well as the thermohaline circulation in the ocean. Thus, being able to monitor and accurately model Arctic rivers is a crucial issue for the understanding of changes in the Arctic water cycle. The Ob River is one of the largest rivers in the Arctic, contributing nearly 15% of total freshwater flow into the Arctic Ocean. A model of the lower Ob River has been implemented, by coupling the land surface scheme ISBA (Interactions between Soil, Biosphere and Atmosphere), developed by the CNRM (Centre National de Recherche Meteorologique, France), with the flood inundation model LISFLOOD-FP, developed by the University of Bristol, UK. The scarcity of in situ data in the Ob River basin leads to large errors in the modelling. The forecast error has been assumed to be only due to uncertainties on forcing data (precipitation and air temperature). These errors can be reduced by implementing an Ensemble Kalman smoother for assimilating remotely sensed water levels from satellite altimeters. Data from the future Surface Water and Ocean Topography (SWOT) satellite wide swath altimeter mission will be particularly well adapted to improve the modelling of the Arctic rivers. Every few days, the Ka Radar Interferometer (KaRIN) on board SWOT will provide, for the first time, a global estimate of surface water elevation (with a vertical accuracy of a few cm). The SWOT data have been simulated and assimilated to estimate and quantify their potential to reduce the modelling errors. Preliminary results, using a local Ensemble Kalman Smoother over a 3 day time frame, show that assimilation of SWOT measurements (for a 22-day repeat orbit) leads to a decrease of model prediction errors by a factor of 2.4.

  17. Improving a modelling of the Ob river, in western Siberia, by assimilating wide swath altimetry data

    NASA Astrophysics Data System (ADS)

    Biancamaria, S.; Durand, M. T.; Andreadis, K.; Bates, P. D.; Boone, A.; Mognard, N. M.; Rodriguez, E.; Alsdorf, D. E.; Lettenmaier, D. P.

    2009-12-01

    Arctic rivers are a main source of fresh water to the Arctic Ocean: they represent nearly 10% of the world’s river runoff, whereas the Arctic Ocean represents only 6% of the global ocean surface area. Therefore, changes in their hydrological regime due to global warming could impact not only the thermohaline circulation, but also the carbon cycle (via their floodplains) and the human societies living in high latitudes. Thus, being able to model major arctic rivers and therefore predict how they may respond to global warming is a crucial issue. The upcoming Surface Water and Ocean Topography (SWOT) satellite mission will use a wide swath Ka-band Radar Interferometer (KaRIN) to acquire elevations of terrestrial water surfaces at unprecedented spatial and temporal resolutions, and will observe all continental water bodies between 78°N and 78°S. These measurements will be of broad interest for the hydrology community in general and for hydrologic/hydraulic modelling in particular. SWOT measurements will explicitly characterize the spatial and temporal surface water variations; thus, assimilating SWOT measurements into hydraulic models has great potential for estimating river discharge. This study presents hydrological modelling of the lower Ob river, in Western Siberia. The Ob is the third largest arctic river and contributes to nearly 15% of the total freshwater flow into the Arctic Ocean. The hydrological modelling has been performed by coupling the land surface scheme ISBA (Interactions between Soil, Biosphere and Atmosphere) with the flood inundation model LISFLOOD-FP. Virtual SWOT data have been computed within the context of a synthetic data assimilation experiment. We use the Ensemble Kalman Filter and Smoother to better assess the potential of the SWOT measurements to provide information about river discharge. Preliminary results show that these measurements could decrease the modelling errors almost to 50% for the nominal satellite orbit. Yet, these

  18. Surface Water and Ocean Topography (SWOT) mission

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Lindstrom, Eric J.; Vaze, Parag V.; Fu, Lee-Lueng

    2012-09-01

    The Surface Water Ocean Topography (SWOT) mission was recommended in 2007 by the National Research Council's Decadal Survey, "Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond", for implementation by NASA. The SWOT mission is a partnership between two communities, the physical oceanography and the hydrology, to share high vertical accuracy and high spatial resolution topography data produced by the science payload, principally a Ka-band radar Interferometer (KaRIn). The SWOT payload also includes a precision orbit determination system consisting of GPS and DORIS receivers, a Laser Retro-reflector Assembly (LRA), a Jason-class nadir radar altimeter, and a JASON-class radiometer for tropospheric path delay corrections. The SWOT mission will provide large-scale data sets of ocean sea-surface height resolving scales of 15km and larger, allowing the characterization of ocean mesoscale and submesoscale circulation. The SWOT mission will also provide measurements of water storage changes in terrestrial surface water bodies and estimates of discharge in large (wider than 100m) rivers globally. The SWOT measurements will provide a key complement to other NASA spaceborne global measurements of the water cycle measurements by directly measuring the surface water (lakes, reservoirs, rivers, and wetlands) component of the water cycle. The SWOT mission is an international partnership between NASA and the Centre National d'Etudes Spatiales (CNES). The Canadian Space Agency (CSA) is also expected to contribute to the mission. SWOT is currently nearing entry to Formulation (Phase A). Its launch is targeted for October 2020.

  19. Defining the Flora Family: Reflectance Properties and Age

    NASA Astrophysics Data System (ADS)

    Dykhuis, Melissa J.; Molnar, Lawrence A.; Van Kooten, Samuel J; Greenberg, Richard

    2014-05-01

    The Flora family resides in the densely populated inner main belt, bounded in semimajor axis by the ν6 secular resonance and the Jupiter 3:1 mean motion resonance. The presence of several large families that overlap dynamically with the Floras (e.g. the Vesta, Baptistina, and Nysa-Polana families), and the removal of a significant fraction of Floras via the nearby ν6 resonance have historically complicated the Flora family's distinction in both proper orbital elements and reflectance properties. Here we use orbital information from AstDyS, color information from SDSS, and albedo information from WISE, to obtain the characteristic orbital and reflectance properties of the Floras, by sampling the core of the family in multidimensional phase space. We find the characteristic Flora SDSS colors to be a* = 0.127 ± 0.012 and i-z = -0.038 ± 0.008; the characteristic Flora albedo is pV = 0.295 ± 0.006. These properties allow us to select a high-purity sample of Floras with similar orbital and reflectance properties as required for a detailed dynamical study. We then use the young Karin family, for which we have an age determined via direct backward integration of members' orbits, to calibrate the Yarkovsky drift rates for the Flora family without having to estimate the Floras' material properties. The size-dependent dispersion of the Flora members in semimajor axis (the "V" plot) then yields an age for the family of 940+160-120 My. We discuss the effects on our age estimate of two independent processes that both introduce obliquity variations among the family members on short (My) timescales: 1) the capture of Flora members in spin-orbit resonance, and 2) YORP-driven obliquity variation through YORP cycles. Accounting for these effects does not significantly change the age determination.

  20. Towards a Global Model of the Zodiacal Cloud

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Dermott, S.; Kehoe, T. J.

    2006-09-01

    The Zodiacal Cloud, the debris disk of our own solar system, is still the subject of much debate as to the source of its particles, i.e., what are the relative contributions of asteroidal and cometary material to the cloud. The Zodiacal Cloud consists of a broad, low-frequency background, with superimposed high-frequency dust bands, which are the key to deciphering the relative contributions, since they are known to be asteroidal and associated with specific, young, asteroid families, such as Veritas and Karin. The dust bands only exist outside 2AU due to the secular resonance at 2AU dispersing the fine structure of the dust bands into the background cloud. Thus, the bands represent only the tip-of-the-iceberg of the total asteroidal contribution to the cloud, the extent of which can be found by investigating the dynamical and collisional evolution of the asteroidal family dust particles. Through this evolution of particles, we can model the observed line-of-sight dust band flux profiles, which are scans of ecliptic latitude. The models are based on the dynamics, and compared to filtered observations to constrain the models. The effects of collisions, size-frequency distribution, distribution of cross sectional area with semi-major axis, and the total area are the parameters that are varied and constrained. There is a wealth of archival data, including IRAS, COBE, and MSX, as well as the upcoming Spitzer data, which both overlap and extend over a wide range of ecliptic longitudes, wavebands, and solar elongations. We will use the parameters constrained by the observational data, to extend the model to the background cloud, yielding a global model of the asteroidal contribution to the cloud. We present current models and parameters, as well as a preliminary determination of the asteroidal contribution to the Zodiacal cloud.

  1. Whither Cometary Dust?

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.

    2010-10-01

    In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

  2. On the Nature of the Dust in the Debris Disk around HD 69830

    NASA Astrophysics Data System (ADS)

    Lisse, C. M.; Beichman, C. A.; Bryden, G.; Wyatt, M. C.

    2007-03-01

    We have used the infrared mineralogical model derived from the Spitzer IRS observations of the Deep Impact experiment to study the nature of the dust in the debris found around the K0 V star HD 69830. Using a robust approach to determine the bulk average mineralogical composition of the dust, we show it to be substantially different from that found for comets 9P/Tempel 1 and C/Hale-Bopp 1995 O1 or for the comet-dominated YSO HD 100546. Lacking in carbonaceous and ferrous materials but including small icy grains, the composition of the HD 69830 dust most closely resembles that of a disrupted P- or D-type asteroid. The amount of mass responsible for the observed emission is the equivalent of a 30 km radius, 2500 kg m-3 sphere, while the radiative temperature of the dust implies that the bulk of the observed material is at ~1.0 AU from the central source, coincident with the 2:1 and 5:2 mean motion resonances of the outermost of three Neptune-sized planets detected by Lovis and coworkers. In our solar system, P- and D-type asteroids are both large and numerous in the outer main belt and near Jupiter (e.g., the Hildas and Trojans) and have undergone major disruptive events to produce debris disk-like structures (cf. the Karin and Veritas families 5-8 Myr ago). The short-lived nature of the small and icy dust implies that the disruption occurred within the last year, or that replenishment due to ongoing collisional fragmentation is occurring.

  3. A Census of Asteroid Families Between the J5/2 and J7/3 Resonances

    NASA Astrophysics Data System (ADS)

    Molnar, Lawrence A.; McKay, C. L.

    2010-10-01

    Significant theoretical progress has been made in recent years in modeling the history of the main asteroid belt. In particular, the size-frequency distributions of individual collisions (as a function of impact properties) and the collisional rate (as a function of target size) have been computed. In this work we test these results against observations of asteroids between the J5/2 and J7/3 mean motion resonances. We select this particular zone because 1) the asteroid density is low enough that the extent and membership of all families may be determined unambiguously, 2) the boundary resonances isolate it from families in other zones, and 3) other resonances within the zone have had relatively little effect on the orbits of its families. In particular, we computed synthetic proper elements for 16,111 multiopposition asteroids. We used proper a, e, i and absolute magnitude to identify membership in 19 collisional families. For two of these_the Karin and Koronis clusters_we also used proper longitudes of node and perihelion. The absolute magnitude is important for excluding large interlopers when a Yarkovsky signature clearly identifies them as such. For example, (293) Brasilia is probably not a member of the family previously identified as the Brasilia family. We corrected size-frequency distribution (SFDs) using the local background rates. Finally, we inferred collisional ages (or limits) from evidence of Yarkovsky broadening of the distribution in a. We will present and discuss the empirical collision rate function implied by our results and the SFDs of the families and of the background asteroids. We will also present and discuss the average Sloan Digital Sky Survey colors for each family. This work was funded by a Kuiper endowment and a Calvin Research Fellowship.

  4. Surface heterogeneity of small asteroids

    NASA Astrophysics Data System (ADS)

    Sasaki, Sho

    A rubble pile model of asteroid origin would predict averaged rather homogeneous surface of an asteroid. Previous spacecraft observations (mostly S-type asteroids) did not show large color/albedo variation on the surface. Vesta would be exceptional since HST observation suggested that its surface should be heterogeneous due to the impact excavation of the interior. As for a young asteroid (832) Karin (age being 5Ma), Sasaki et al. (2004) detected variation of infrared spectra which could be explained by the difference of the space weathering degree. They discussed the possibility of the survival of the old surface. However, the variation was not confirmed by later observation (Chapman et al., 2007; Vernazza et al., 2007). Recent observation of a small (550m) asteroid Itokawa by Hayabusa spacecraft revealed that Itokawa is heterogeneous in color and albedo although the overall rocky structure is considered as a rubble pile (Saito et al., 2006). The color difference can be explained by the difference of weathering degree (Ishiguro et al., 2008). The heterogeneity could be explained by mass movement caused by rapid rotation from YORP effect (Scheeres et al., 2007) or seismic shaking (Sasaki, 2006). Probably small silicate asteroids without significant regolith could have heterogeneous in color and albedo. On large asteroids (˜ a few 10km), regolith reaccumulation should have covered the underlying heterogeneity. References: Chapman, C. R. et al (2007) Icarus, 191, 323-329 Ishiguro, M. et al. (2008) MAPS, in press. Saito, J. et al. (2006) Science, 312, 1341-1344 Sasaki, S. (2006) in Spacecraft Reconnaissance of Asteroid and Comet Interiors Sasaki, T. et al (2004) Astrophys. J. 615, L161-L164 Scheeres, D. J. (2007) Icarus 188, 425-429 Vernazza, P. et al. (2007) Icarus 191, 330-336.

  5. High Latitude Dust Bands in the Main Asteroid Belt: Fingerprints of Recent Breakup Events

    NASA Astrophysics Data System (ADS)

    Bottke, William; Durda, Daniel; Jayaraman, Sumita; Lien, David; Nesvorny, David; Reach, William; Stansberry, John; Sykes, Mark; Walker, Russell

    2005-06-01

    The present population of main belt asteroids is largely the result of many past collisions. Ideally, the fragments produced by each impact event could help us understand the collisional processes that shaped the planets during early epochs. Most known asteroid fragment families, however, are very old and thus have undergone significant collisional and dynamical evolution since their formation. This evolution masks the properties of the original collisions. To overcome this problem, our team has used numerical methods and a large database of asteroid orbits to identify several families produced by recent disruption events (<< few tens of My). Not only have these young families undergone little collisional and dynamical evolution, but several of them appear to be the source of dust bands observed by IRAS (e.g., the Karin and Veritas families, both which are < 10 My old; Nesvorny et al. 2002; 2003). Here we propose to use Spitzer observations to investigate the structure of high latitude dust bands in the main asteroid belt. Our results indicate that 2 faint dust bands identified by IRAS, the J/K band at proper inclination i = 12 deg and the M/N band at i = 15 deg, were produced by break up events associated with asteroids (4652) Iannini and (1521) Seinajoki, respectively. Numerical integration work by our team suggests the former family is < 5 My old, making it the youngest family yet discovered in the main belt. Taking advantage of the increased sensitivity of Spitzer over IRAS, we will determine the dust production rate and size distribution in the high latitude bands, relate them to the Zodiacal Cloud, and use this data to constrain main belt collisional processes.

  6. An ensemble-based reanalysis approach for estimating river bathymetry from the upcoming SWOT mission

    NASA Astrophysics Data System (ADS)

    Yoon, Y.; Durand, M. T.; Merry, C. J.; Clark, E.; Alsdorf, D. E.

    2011-12-01

    In spite of the critical role of river discharge in land surface hydrology, global gauging networks are sparse and even have been in decline. Over the past decade, researchers have been trying to better estimate river discharge using remote sensing techniques to complement the existing in-situ gage networks. The upcoming Surface Water and Ocean Topography (SWOT) mission will directly provide simultaneous spatial mapping of inundation area (A) and inland water surface elevation (WSE) data (i.e., river, lakes, wetlands, and reservoirs), both temporally (dh/dt) and spatially (dh/dx), with the Ka-band Radar INterferometer (KaRIN). With these observations, the SWOT mission will provide the measurements of water storage changes in terrestrial surface water bodies. However, because the SWOT will measure WSE, not the true depth to the river bottom, the cross section channel bathymetry will not be fully measured. Thus, estimating bathymetry is important in order to produce accurate estimates of river discharge from the SWOT data. In previous work, a local ensemble Kalman filter (LEnKF) was used to estimate the river bathymetry, given synthetic SWOT observations and WSE predictions by the LISFLOOD-FP hydrodynamic model. However, the accuracy of river bathymetry was highly affected by the severe bias of boundary inflows due to the mathematical relationship for the assimilation. The bias in model is not accounted for the data assimilation. Here, we focus on correcting the forecast bias for the LEnKF scheme to result in the improvement of river bathymetry estimates. To correct the forecast bias and improve the accuracy, we combined the LEnKF scheme with continuity and momentum equations. To evaluate the reanalysis approach, the error of bathymetry was evaluated by comparing with the true value and previous work. In addition, we examined the sensitivity to the bathymetry estimate for estimating the river discharge.

  7. Sestrin2 promotes LKB1-mediated AMPK activation in the ischemic heart

    PubMed Central

    Morrison, Alex; Chen, Li; Wang, Jinli; Zhang, Ming; Yang, Hui; Ma, Yina; Budanov, Andrei; Lee, Jun Hee; Karin, Michael; Li, Ji

    2015-01-01

    The regulation of AMPK in the ischemic heart remains incompletely understood. Recent evidence implicates the role of Sestrin2 in the AMPK signaling pathway, and it is hypothesized that Sestrin2 plays an influential role during myocardial ischemia to promote AMPK activation. Sestrin2 protein was found to be expressed in adult cardiomyocytes and accumulated in the heart during ischemic conditions. Sestrin2 knockout (KO) mice were used to determine the importance of Sestrin2 during ischemia and reperfusion (I/R) injury. When wild-type (WT) and Sestrin2 KO mice were subjected to in vivo I/R, myocardial infarct size was significantly greater in Sestrin2 KO compared with WT hearts. Similarly, Langendorff perfused hearts indicated exacerbated postischemic contractile function in Sestrin2 KO hearts compared with WT. Ischemic AMPK activation was found to be impaired in the Sestrin2 KO hearts. Immunoprecipitation of Sestrin2 demonstrated an association with AMPK. Moreover, liver kinase B1 (LKB1), a major AMPK upstream kinase, was associated with the Sestrin2-AMPK complex in a time-dependent manner during ischemia, whereas this interaction was nearly abolished in Sestrin2 KO hearts. Thus, Sestrin2 plays an important role in cardioprotection against I/R injury, serving as an LKB1-AMPK scaffold to initiate AMPK activation during ischemic insults.—Morrison, A., Chen, L. Wang, J., Zhang, M., Yang, H., Ma, Y., Budanov, A., Lee, J. H., Karin, M., Li, J. Sestrin2 promotes LKB1-mediated AMPK activation in the ischemic heart. PMID:25366347

  8. Infrared Sources in the Small Magellanic Cloud: First Results

    NASA Astrophysics Data System (ADS)

    Simon, J. D.; Bolatto, A. D.; Stanimirovic, S.; Shah, R. Y.; Leroy, A.; Sandstrom, K.

    2008-03-01

    We have imaged the entire Small Magellanic Cloud (SMC), one of the two nearest star-forming dwarf galaxies, in all seven IRAC and MIPS bands. The low mass and low metallicity (1/6 solar) of the SMC make it the best local analog for primitive galaxies at high redshift. By studying the properties of dust and star formation in the SMC at high resolution, we can gain understanding of similar distant galaxies that can only be observed in much less detail. In this contribution, we present a preliminary analysis of the properties of point sources detected in the Spitzer Survey of the Small Magellanic Cloud (S^{3}MC). We find ˜400,000 unresolved or marginally resolved sources in our IRAC images, and our MIPS 24 μm mosaic contains ˜17,000 point sources. Source counts decline rapidly at the longer MIPS wavelengths. We use color-color and color-magnitude diagrams to investigate the nature of these objects, cross-correlate their positions with those of known sources at other wavelengths, and show examples of how these data can be used to identify interesting classes of objects such as carbon stars and young stellar objects. For additional examples of some of the questions that can be studied with these data, please see the accompanying contributions by Alberto Bolatto (survey information and images), Adam Leroy (dust and gas in a low-metallicity environment), Karin Sandstrom (far infrared-radio continuum correlation), and Snežana Stanimirović (on a young supernova remnant in the SMC). The mosaic images and point source catalogs we have made have been released to the public on our website (http://celestial.berkeley.edu/spitzer).

  9. Dynamical and Collisional Evolution of Asteroidal Dust Particles and the Structure of the Solar System Dust Bands

    NASA Astrophysics Data System (ADS)

    Dermott, S. F.; Kehoe, T. J. J.; Mahoney-Hopping, L.

    2005-12-01

    Recent modeling of the solar system dust bands has shown a significant discrepancy between the mean proper inclinations of the "ten-degree" band and the Eos asteroid family, its putative source. This has led to the suggestion that the dust bands did not result from the gradual comminution of large, ancient asteroid families but were instead produced by recent catastrophic disruptions of asteroids, such as those that generated the Karin cluster and the Veritas family. The small particles produced in such collisional events spiral rapidly into the Sun under the effect of Poynting-Robertson (P-R) drag. Larger particles have correspondingly longer P-R drag lifetimes but are more likely to be fragmented by inter-particle collisions. It is these large particles and their collisional fragments that we observe today as the dust bands, the decaying remnant of a much larger influx of material. The structure of the dust bands is therefore determined by the combined dynamical and collisional behavior of a realistic size distribution of particles. We present the results of numerical simulations showing the evolution of asteroidal dust particles under the effects of radiation pressure, P-R drag, solar wind drag, planetary perturbations, and stochastic size changes due to particle fragmentation. These results reveal that: (i) the orientation of the mean plane of symmetry of the dust bands outside 2AU is dominated by the effect of Jupiter as it evolves through its secular cycle and it is for this reason that we are able to observe the bands; (ii) the effect of inter-particle collisions introduces dispersion in the distribution of the particle orbits; and (iii) the inner edge to the dust bands at 2AU is a consequence of the effect of secular resonances dispersing particle orbits to the extent that the dust band signal merges into the flux from the background zodiacal cloud.

  10. Retrieving High Precision River Stages and Slopes from Space

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Moller, D.

    2005-12-01

    Conventional radar altimetry has been successful in retrieving water level measurements at altimeter crossings with an accuracy of 10cm to 20cm. Although promising, this measurement accuracy is insufficient to provide global monitoring of fresh water bodies, as has been proposed by the WatER mission, for instance. In this paper we examine in detail the error sources that a near-nadir synthetic aperture radar interferometer, such as the KaRIN instrument proposed to meet the WatER requirements, will be subject to and demonstrate that with appropriate calibration techniques, measurements of river stage with an accuracy of approximately 5 cm and river slope with an accuracy of 1 cm/1km can be obtained. In the first part, we examine the main error contributors to the height measurements and quantify the expected magnitude of the errors. The errors sources examined include tropospheric effects, spacecraft orbit and attitude stability, the effect of vegetation, and the effect of topographic lay-over. These sources of error are examined analytically and also with the help of an instrument simulation which includes all error sources to generate simulated measurements. Simulated performance results will be presented for the Ohio river basin and for the Amazon basin at the Solimoes/Puros confluence. In the second part, we examine calibration techniques to mitigate the errors mentioned above and demonstrate the feasibility of achieving the height and slope performance given in the first paragraph. Simulated calibration results will be presented for both Ohio and Amazon basins. Finally, we propose a method for processing the interferometer data to optimally filter random measurement noise and provide high precision estimates of river stage and slope which can be assimilated simply into hydrologic models or used in conjunction with ancillary data or physical assumptions to provide estimates of river discharge.

  11. Recent Breakups in the Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Nesvorny, D.

    2005-08-01

    Much of what we see in the asteroid belt today is a consequence of past collisions, which shaped the size-frequency distribution of asteroids and led to their heavily-cratered surfaces. Perhaps the most remarkable features of the belt are the asteroid families [1]. An asteroid family is a group of asteroid fragments with similar orbits and spectra produced by a collisional breakup of a large parent body. More than fifty families have been identified to date in the main belt [2]. These structures, when properly analyzed, hold important clues to the interior structure of asteroids, the physics of large scale collisions, and the overall evolution of the main belt since its formation [3]. Most of the known families are very old and thus have experienced significant dynamical and collisional erosion since their formation. This makes it difficult to clearly distinguish between features produced by the original breakup and those produced by on-going processes. Recent dynamical studies, however, have identified several asteroid families that are extremely young: the Iannini, Karin and Veritas families apparently formed at <5, 5.8 and 8.3 Ma, respectively [4,5]. These families represent nearly pristine examples of ejected fragments produced by disruptive asteroid collisions, because the observed remnants of recent breakups have apparently suffered limited dynamical and collisional erosion. Here we will discuss how studies of young asteroid families help us glean insights into the physics of large scale collisions, dynamical processes that affect small bodies in the Solar System, and the surface and interior properties of asteroids. [1] Hirayama, 1918, AJ 31, 185--188. [2] Zappala et al., 2002, In Asteroids III, pp. 619-629. [3] Bottke et al., 2005, Icarus, 175, 111-140. [4] Nesvorny et al., 2002, Nature 417, 720--722. [5] Nesvorny et al., 2003, ApJ 591, 486--497.

  12. A New Solar System Dust Band

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Dermott, S. F.; Kehoe, T. J.; Jayaraman, S.

    2007-10-01

    The relative proportions of asteroidal and cometary material in the zodiacal cloud is an evolving debate. The determination of the asteroidal component is constrained through the study of the dust bands (the fine-structure component superimposed on the broad background cloud), since they have been confidently linked to specific, young, asteroid family disruptions in the main belt. These disruptions represent recent injections of dust into the cloud and thus hold the key to determining at least a minimum value of the asteroidal contribution. There are currently known to be three dust band pairs, one at approximately 10 degrees corresponding to the Veritas family and two central band pairs near the ecliptic, one of which corresponds to the Karin cluster of the Koronis family. However, through careful co-adding of almost all the pole-to-pole intensity scans in the mid infrared wavebands of the IRAS data set, a new solar system dust band has been found at approximately 17 degrees inclination. We think this is a confirmation of the M/N partial band pair suggested by Sykes (1988). The new dust band appears to be mostly, yet not completely formed, which we attribute to the young age of the likely sources. We will present dynamical modeling of the new band which allows us to determine the most likely source and amount of cross-sectional area of dust in the band. This is turn allows us to put constraints on the size of the precursor and amount of dust contributed by this source to the background cloud. Since the band is incomplete, the dynamics of the distribution of the node will allow us to put loose constraints on the time of formation of this band and compare with the ages of the potential sources. This work is funded by NASA GSRP.

  13. Evidence from IRAS for a very young, partially formed dust band

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Dermott, Stanley F.; Kehoe, Thomas J. J.; Jayaraman, Sumita

    2009-02-01

    The relative proportions of asteroidal and cometary materials in the zodiacal cloud is an ongoing debate. The determination of the asteroidal component is constrained through the study of the Solar System dust bands (the fine-structure component superimposed on the broad background cloud), since they have been confidently linked to specific, young, asteroid families in the main belt. The disruptions that produce these families also result in the injection of dust into the cloud and thus hold the key to determining at least a minimum value for the asteroidal contribution to the zodiacal cloud. There are currently known to be at least three dust band pairs, one at approximately 9.35° associated with the Veritas family and two central band pairs near the ecliptic, one of which is associated with the Karin subcluster of the Koronis family. Through careful co-adding of almost all the pole-to-pole intensity scans in the mid-infrared wavebands of the Infrared Astronomical Satellite (IRAS) data set, we find strong evidence for a partial Solar System dust band, that is, a very young dust band in the process of formation, at approximately 17° latitude. We think this is a confirmation of the M/N partial band pair first suggested by Sykes [1988. IRAS observations of extended zodiacal structures. Astrophys. J. 334, L55-L58]. The new dust band appears at some but not all ecliptic longitudes, as expected for a young, partially formed dust band. We present preliminary modeling of the new, partial dust band which allows us to put constraints on the age of the disruption event, the inclination and node of the parent body at the time of disruption, and the quantity of dust injected into the zodiacal cloud.

  14. Size-frequency distributions of fragments from SPH/ N-body simulations of asteroid impacts: Comparison with observed asteroid families

    NASA Astrophysics Data System (ADS)

    Durda, Daniel D.; Bottke, William F.; Nesvorný, David; Enke, Brian L.; Merline, William J.; Asphaug, Erik; Richardson, Derek C.

    2007-02-01

    We investigate the morphology of size-frequency distributions (SFDs) resulting from impacts into 100-km-diameter parent asteroids, represented by a suite of 161 SPH/N-body simulations conducted to study asteroid satellite formation [Durda, D.D., Bottke, W.F., Enke, B.L., Merline, W.J., Asphaug, E., Richardson, D.C., Leinhardt, Z.M., 2004. Icarus 170, 243-257]. The spherical basalt projectiles range in diameter from 10 to 46 km (in equally spaced mass increments in logarithmic space, covering six discrete sizes), impact speeds range from 2.5 to 7 km/s (generally in 1 km/s increments), and impact angles range from 15° to 75° (nearly head-on to very oblique) in 15° increments. These modeled SFD morphologies match very well the observed SFDs of many known asteroid families. We use these modeled SFDs to scale to targets both larger and smaller than 100 km in order to gain insights into the circumstances of the impacts that formed these families. Some discrepancies occur for families with parent bodies smaller than a few tens of kilometers in diameter (e.g., 832 Karin), however, so due caution should be used in applying our results to such small families. We find that ˜20 observed main-belt asteroid families are produced by the catastrophic disruption of D >100 km parent bodies. Using these data as constraints, collisional modeling work [Bottke Jr., W.F., Durda, D.D., Nesvorný, D., Jedicke, R., Morbidelli, A., Vokrouhlický, D., Levison, H.F., 2005b. Icarus 179, 63-94] suggests that the threshold specific energy, QD∗, needed to eject 50% of the target body's mass is very close to that predicted by Benz and Asphaug [Benz, W., Asphaug, E., 1999. Icarus 142, 5-20].

  15. Prey consumption by the juvenile soles, Solea solea and Solea senegalensis, in the Tagus estuary, Portugal

    NASA Astrophysics Data System (ADS)

    Vinagre, C.; Cabral, H. N.

    2008-06-01

    The soles Solea solea and Solea senegalensis are marine flatfish that use coastal and estuarine nursery grounds, which generally present high food availability, refuge from predators and favourable conditions for rapid growth. Two important nursery grounds for these species juveniles have been identified in the Tagus estuary, one in the upper part of the estuary (nursery A) and another in the south bank (nursery B). While S. solea is only present at the uppermost nursery area, S. senegalensis is present at both nurseries. Although they are among the most important predators in these nursery grounds, there are no estimates on their food consumption or on the carrying capacity of the system for soles. The Elliott and Persson [1978. The estimation of daily rates of food consumption for fish. Journal of Animal Ecology 47, 977-993] model was used to estimate food consumption of both species juveniles in both nursery areas, taking into account gastric evacuation rates (previously determined) and 24 h sampling surveys, based on beam-trawl catches carried out every 3 h, in the summer of 1995. Monthly beam trawls were performed to determine sole densities over the summer. Density estimates and daily food consumption values were used to calculate total consumption over the summer period. Sediment samples were taken for the estimation of prey densities and total biomass in the nursery areas. Daily food consumption was lower for S. solea (0.030 g wet weight d -1) than for S. senegalensis (0.075 g wet weight d -1). It was concluded that thermal stress may be an important factor hindering S. solea's food consumption in the warmer months. Total consumption of S. solea over the summer (90 days) was estimated to be 97 kg (wet weight). Solea senegalensis total consumption in nursery A was estimated to be 103 kg, while in nursery B it was 528 kg. Total prey biomass estimated for nursery A was 300 tonnes, while for nursery B it was 58 tonnes. This suggests that food is not a limiting

  16. Delineating Potential Quick-clay Areas Using High-resolution Seismic Methods: Towards a 3D Model of an Area Prone to Slide in SW Sweden

    NASA Astrophysics Data System (ADS)

    Salas Romero, S.; Malehmir, A.; Snowball, I.

    2015-12-01

    , Krawzyck C, Gurk M, Ismail N, Polom U, Persson L (2013) Geophysical assessment and geotechnical investigation of quick-clay landslides—a Swedish case study. Near Surface Geophysics, 11, 341-350

  17. An Imaging and Spectroscopic Study of Four Strong Mg II Absorbers Revealed by GRB 060418

    NASA Astrophysics Data System (ADS)

    Pollack, L. K.; Chen, H.-W.; Prochaska, J. X.; Bloom, J. S.

    2009-08-01

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) gsim 1 Å revealed by the afterglow of GRB 060418 at z GRB = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z GRB, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Lyα systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at Δ θ lsim 3farcs5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity ≈0.1 - 1 L * at impact parameter of ρ lsim 10 h -1 kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of ρ = 2 - 12 h -1 kpc from the afterglow. At the afterglow's position, we derive a 2σ upper limit to the underlying star-formation rate intensity of 0.0074 M sun yr-1 kpc-2. Based in part on observations made with the NASA/ESA Hubble Space Telescope

  18. AN IMAGING AND SPECTROSCOPIC STUDY OF FOUR STRONG Mg II ABSORBERS REVEALED BY GRB 060418

    SciTech Connect

    Pollack, L. K.; Prochaska, J. X.; Chen, H.-W.; Bloom, J. S.

    2009-08-20

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) {approx}> 1 A revealed by the afterglow of GRB 060418 at z{sub GRB} = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z {sub GRB}, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Ly{alpha} systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at {delta} {theta} {approx}< 3.''5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity {approx}0.1 - 1 L{sub *} at impact parameter of {rho} {approx}< 10 h {sup -1} kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of {rho} = 2 - 12 h {sup -1} kpc from the afterglow. At the afterglow's position, we derive a 2{sigma} upper limit to the underlying star-formation rate intensity of 0.0074 M{sub sun} yr{sup -1} kpc

  19. The influence of chemical composition on the properties of Cepheid stars. II. The iron content

    NASA Astrophysics Data System (ADS)

    Romaniello, M.; Primas, F.; Mottini, M.; Pedicelli, S.; Lemasle, B.; Bono, G.; François, P.; Groenewegen, M. A. T.; Laney, C. D.

    2008-09-01

    Context: The Cepheid period-luminosity (PL) relation is unquestionably one of the most powerful tools at our disposal for determining the extragalactic distance scale. While significant progress has been made in the past few years towards its understanding and characterization both on the observational and theoretical sides, the debate on the influence that chemical composition may have on the PL relation is still unsettled. Aims: With the aim to assess the influence of the stellar iron content on the PL relation in the V and K bands, we have related the V-band and the K-band residuals from the standard PL relations of Freedman et al. (2001, ApJ, 553, 47) and Persson et al. (2004, AJ, 128, 2239), respectively, to [Fe/H]. Methods: We used direct measurements of the iron abundances of 68 Galactic and Magellanic Cepheids from FEROS and UVES high-resolution and high signal-to-noise spectra. Results: We find a mean iron abundance ([Fe/H]) about solar (σ = 0.10) for our Galactic sample (32 stars), ~-0.33 dex (σ = 0.13) for the Large Magellanic Cloud (LMC) sample (22 stars) and ~-0.75 dex (σ = 0.08) for the Small Magellanic Cloud (SMC) sample (14 stars). Our abundance measurements of the Magellanic Cepheids double the number of stars studied up to now at high resolution. The metallicity affects the V-band Cepheid PL relation and metal-rich Cepheids appear to be systematically fainter than metal-poor ones. These findings depend neither on the adopted distance scale for Galactic Cepheids nor on the adopted LMC distance modulus. Current data do not allow us to reach a firm conclusion concerning the metallicity dependence of the K-band PL relation. The new Galactic distances indicate a small effect, whereas the old ones support a marginal effect. Conclusions: Recent robust estimates of the LMC distance and current results indicate that the Cepheid PL relation is not Universal. Based on observations made with ESO Telescopes at Paranal and La Silla Observatories under

  20. Precision photometry of early-type galaxies in the Coma and Virgo clusters: A test of the universality of the colour-magnitude relation. I - The data. II. Analysis

    NASA Astrophysics Data System (ADS)

    Bower, Richard G.; Lucey, J. R.; Ellis, Richard S.

    1992-02-01

    We have undertaken a comprehensive study of a large sample of early-type galaxies in the Virgo and Coma clusters. In the first of two papers, we present accurate UVJK photometry for a total of 94 elliptical and SO galaxies. All U- and V-band measurements are based on CCD observations made with the 2.5-m Isaac Newton Telescope. J- and K-band observations for the Coma cluster were made with a chopping photometer at the United Kingdom Infrared Telescope (UKIRT). Virgo J and K-band measurements have been taken from Persson, Frogel & Aaronson. The rms internal scatter of these data are respectively: 0.025, 0.015, 0.03 and 0.03 mag for Virgo U V J and K (60-arcsec aperture) measurements; 0.030, 0.021, 0.026 and 0.027 mag for Coma U, V (1 3-arcsec aperture), J and K (1 7-arcsec aperture) measurements. We have been careful to ensure that the data set is internally homogeneous. We estimate that the photometric zero-points in the two clusters agree to better than 0.01 mag for U and V and 0.02 mag for J and K. From these measurements, we have derived U - V V- K and J - K colours corrected for redshift, galactic extinction and aperture effects. After allowing for the systematic uncertainties in these corrections, we estimate that the U - V V - K and J - K colour systems in both clusters are matched to better than 0.02, 0.03 and 0.04 mag respectively. This data set is completed by photometric diameter parameters derived from our own V-band data, total V-band magnitudes derived from a combination of our measurements and those of Godwin & Peach and Michard, and velocity dispersions and morphological types taken from the literature. A detailed analysis of colour-magnitude correlations of these galaxies will be presented in Paper II (this issue).

  1. Water in the warm inner regions of Class 0 protostars

    NASA Astrophysics Data System (ADS)

    Coutens, Audrey; Jørgensen, Jes K.; Persson, Magnus V.; van Dishoeck, Ewine; vastel, charlotte; Taquet, Vianney; Bottinelli, Sandrine; Caux, Emmanuel; Harsono, Daniel; Lykke, Julie M.

    2015-08-01

    Water plays a key role in many astrophysical environments (star-forming regions, outflows, prestellar cores, comets, asteroids, …) as well as for the emergence of life as we know it. Its detection in the inner regions of low-mass protostars raises the question whether this is similar to the water that is incorporated into comets and asteroids that may deliver it to Earth-like planets. The water deuterium fractionation is very helpful to understand how it forms and evolves. For example, Cleeves et al. (2014) showed that a contribution of water formed in the primordial cloud is necessary to explain the HDO/H2O ratio of the terrestrial oceans. Observations of the deuterated and non-deuterated forms of water at an early stage of star formation may therefore potentially be an important tool to describe the origin of water on Earth.We here present recent interferometric measurements of the distribution and deuteration of water on Solar System scales. During the last few years, a few HDO and H218O lines were observed in the inner regions of Class 0 protostars with interferometers (Jørgensen & van Dishoeck 2010, Codella+2010, Persson+ 2012, 2013, 2014, Taquet+ 2013), which enables estimates of the HDO/H2O ratios. Our recent detection of D2O with the Plateau de Bure interferometer towards the low-mass protostar NGC1333 IRAS2A leads to a surprisingly high D2O/HDO ratio compared with the HDO/H2O ratio (Coutens+ 2014). These results contradict the predictions of current grain surface chemical models and indicate that either an ingredient is missing in our understanding of the surface deuteration process or that both sublimation of grain mantles and water formation at high temperature (T > 230K) take place in the inner regions of protostars. We also present the first results of an ALMA Cycle 2 program (PI: A. Coutens) to target several HDO, H218O and D2O lines at a spatial resolution of ~0.3" (40 AU) toward the nearby protostellar binary IRAS16293-2422. These observations

  2. Real-time sub-Ångstrom imaging of reversible and irreversible conformations in rhodium catalysts and graphene

    NASA Astrophysics Data System (ADS)

    Kisielowski, Christian; Wang, Lin-Wang; Specht, Petra; Calderon, Hector A.; Barton, Bastian; Jiang, Bin; Kang, Joo H.; Cieslinski, Robert

    2013-07-01

    The dynamic responses of a rhodium catalyst and a graphene sheet are investigated upon random excitation with 80 kV electrons. An extraordinary electron microscope stability and resolution allow studying temporary atom displacements from their equilibrium lattice sites into metastable sites across projected distances as short as 60 pm. In the rhodium catalyst, directed and reversible atom displacements emerge from excitations into metastable interstitial sites and surface states that can be explained by single atom trajectories. Calculated energy barriers of 0.13 eV and 1.05 eV allow capturing single atom trapping events at video rates that are stabilized by the Rh [110] surface corrugation. Molecular dynamics simulations reveal that randomly delivered electrons can also reversibly enhance the sp3 and the sp1 characters of the sp2-bonded carbon atoms in graphene. The underlying collective atom motion can dynamically stabilize characteristic atom displacements that are unpredictable by single atom trajectories. We detect three specific displacements and use two of them to propose a path for the irreversible phase transformation of a graphene nanoribbon into carbene. Collectively stabilized atom displacements greatly exceed the thermal vibration amplitudes described by Debye-Waller factors and their measured dose rate dependence is attributed to tunable phonon contributions to the internal energy of the systems. Our experiments suggest operating electron microscopes with beam currents as small as zepto-amperes/nm2 in a weak-excitation approach to improve on sample integrity and allow for time-resolved studies of conformational object changes that probe for functional behavior of catalytic surfaces or molecules.

  3. Centennial of the string galvanometer and the electrocardiogram.

    PubMed

    Fisch, C

    2000-11-15

    This article is a review of the history of the string galvanometer and of the electrocardiogram (ECG) on the occasion of the centennial of the instrument. Einthoven most likely developed the string galvanometer prior to 1901, the date of the first publication. The galvanometer made electrocardiography practical creating a new branch of medicine and even a new industry. In 1791 Galvani, in 1842 Mateucci and in 1855 Kolliker and Muller recorded, using the nerve muscle preparation, contraction of injured muscle, contraction of muscle when laid across a beating heart, and occasionally two contractions. In 1872 Lippmann introduced the capillary manometer. Using the capillary manometer Waller recorded for the first time from body surface voltage changes generated by the heart. Einthoven and Lewis dominated the early years of electrocardiography. The former made his contributions by 1913 while Lewis continued the studies of arrhythmias until 1920. The period following 1920 was influenced largely by Wilson. None did as much to advance ECG knowledge as did Wilson. The interest shifted to the theory of the ECG, abnormalities of wave form and of ECG leads. A major contribution of the ECG is in evaluation of ischemic heart disease and cardiac arrhythmias. Issues facing electrocardiography in the year 2000 include a shortage of experienced electrocardiographers, the advent of new noninvasive procedures and, paradoxically, wide acceptance of the ECG by the medical profession. The role of the computer in analysis of the clinical ECG is limited. The technique, while reasonably reliable for analysis of the normal tracing and some ECG waveforms, has serious limitations when applied to arrhythmias. The early hopes for "stand-alone" programs are yet to be realized. PMID:11092639

  4. History of precordial leads in electrocardiography.

    PubMed

    Burch, G E

    1978-09-01

    Precordial leads were first used by Waller, whose capillary electroscope was too insensitive to detect the electric forces emanating from the human heart unless the electrode was placed over the precordium as near to the heart as possible. When Einthoven developed the elegant, reliable and sensitive string galvanometer, he could record the electric forces of the heart from the hands and feet of the subject without even undressing him. When Einthoven's great galvanometer became available, only the three standard limb leads were used. Thomas Lewis and others experimented with precordial direct leads and made many important discoveries in electrocardiography and cardiology. Wolferth and Wood, in 1932, introduced the first precordial lead in clinical, diagnostic cardiology. The recordings were 'upside-down', i.e. positive deflections were down and negative ones up. They called this the 4th lead (lead IV). The precordial electrode was placed on the chest over the apex of the heart, regardless of where the apex was located. This immediately opened new avenues of study in infarction, ventricular hypertrophy, bundle branch block, and all other cardiac states. Then CL, CR, CF, CB and V leads were introduced. The points considered best for placing the 'exploring' or precordial electrode became an issue, and much confusion prevailed until Wilson and his associates developed the central or isopotential terminal and until the American Heart Association and the Heart Society of Britain and Ireland met in London and published the standards for recording precordial leads in 1938. There followed, for obvious reasons, a slow settling of the confusion until the V1 through V6 precordial leads became standard procedure all over the world, as exists today. Goldberger introduced the augmented unipolar limb leads (aVR, aVL and aVF) which have resulted in the standard 12-lead electrocardiogram of routine use today. No one would consider an electrocardiographic evaluation adequate in a

  5. How electricity was discovered and how it is related to cardiology.

    PubMed

    de Micheli-Serra, Alfredo; Iturralde-Torres, Pedro; Izaguirre-Ávila, Raúl

    2012-01-01

    We relate the fundamental stages of the long road leading to the discovery of electricity and its uses in cardiology. The first observations on the electromagnetic phenomena were registered in ancient texts; many Greek and Roman writers referred to them, although they provided no explanations. The first extant treatise dates back to the XIII century and was written by Pierre de Maricourt during the siege of Lucera, Italy, by the army of Charles of Anjou, French king of Naples. There were no significant advances in the field of magnetism between the appearance of this treatise and the publication of the study De magnete magneticisque corporibus (1600) by the English physician William Gilbert. Scientists became increasingly interested in electromagnetic phenomena occurring in certain fish, i.e., the so-called electric ray that lived in the South American seas and the Torpedo fish that roamed the Mediterranean Sea. This interest increased in the 18th century, when condenser devices such as the Leyden jar were explored. It was subsequently demonstrated that the discharges produced by "electric fish" were of the same nature as those produced in this device. The famous "controversy" relating to animal electricity or electricity inherent to an animal's body also arose in the second half of the 18th century. The school of thought of the physicist Volta sustained the principle of a single electrical action generated by metallic contact. This led Volta to invent his electric pile, considered as the first wet cell battery. Toward the middle of the XIX century, the disciples of the physiologist Galvani were able to demonstrate the existence of animal electricity through experiments exploring the so-called current of injury. On the path of Volta's approach, many characteristics of electricity were detailed, which ultimately led to their usage in the industrial field. The route followed by Galvani-Nobili-Matteucci led to the successes of Waller, Einthoven, etcetera, enabling the

  6. Mode localization in the cooperative dynamics of protein recognition

    NASA Astrophysics Data System (ADS)

    Copperman, J.; Guenza, M. G.

    2016-07-01

    The biological function of proteins is encoded in their structure and expressed through the mediation of their dynamics. This paper presents a study on the correlation between local fluctuations, binding, and biological function for two sample proteins, starting from the Langevin Equation for Protein Dynamics (LE4PD). The LE4PD is a microscopic and residue-specific coarse-grained approach to protein dynamics, which starts from the static structural ensemble of a protein and predicts the dynamics analytically. It has been shown to be accurate in its prediction of NMR relaxation experiments and Debye-Waller factors. The LE4PD is solved in a set of diffusive modes which span a vast range of time scales of the protein dynamics, and provides a detailed picture of the mode-dependent localization of the fluctuation as a function of the primary structure of the protein. To investigate the dynamics of protein complexes, the theory is implemented here to treat the coarse-grained dynamics of interacting macromolecules. As an example, calculations of the dynamics of monomeric and dimerized HIV protease and the free Insulin Growth Factor II Receptor (IGF2R) domain 11 and its IGF2R:IGF2 complex are presented. Either simulation-derived or experimentally measured NMR conformers are used as input structural ensembles to the theory. The picture that emerges suggests a dynamical heterogeneous protein where biologically active regions provide energetically comparable conformational states that are trapped by a reacting partner in agreement with the conformation-selection mechanism of binding.

  7. Mode localization in the cooperative dynamics of protein recognition.

    PubMed

    Copperman, J; Guenza, M G

    2016-07-01

    The biological function of proteins is encoded in their structure and expressed through the mediation of their dynamics. This paper presents a study on the correlation between local fluctuations, binding, and biological function for two sample proteins, starting from the Langevin Equation for Protein Dynamics (LE4PD). The LE4PD is a microscopic and residue-specific coarse-grained approach to protein dynamics, which starts from the static structural ensemble of a protein and predicts the dynamics analytically. It has been shown to be accurate in its prediction of NMR relaxation experiments and Debye-Waller factors. The LE4PD is solved in a set of diffusive modes which span a vast range of time scales of the protein dynamics, and provides a detailed picture of the mode-dependent localization of the fluctuation as a function of the primary structure of the protein. To investigate the dynamics of protein complexes, the theory is implemented here to treat the coarse-grained dynamics of interacting macromolecules. As an example, calculations of the dynamics of monomeric and dimerized HIV protease and the free Insulin Growth Factor II Receptor (IGF2R) domain 11 and its IGF2R:IGF2 complex are presented. Either simulation-derived or experimentally measured NMR conformers are used as input structural ensembles to the theory. The picture that emerges suggests a dynamical heterogeneous protein where biologically active regions provide energetically comparable conformational states that are trapped by a reacting partner in agreement with the conformation-selection mechanism of binding. PMID:27394125

  8. Spinel materials for Li-ion batteries: new insights obtained by operando neutron and synchrotron X-ray diffraction.

    PubMed

    Bianchini, Matteo; Fauth, François; Suard, Emmanuelle; Leriche, Jean Bernard; Masquelier, Christian; Croguennec, Laurence

    2015-12-01

    In the last few decades Li-ion batteries changed the way we store energy, becoming a key element of our everyday life. Their continuous improvement is tightly bound to the understanding of lithium (de)intercalation phenomena in electrode materials. Here we address the use of operando diffraction techniques to understand these mechanisms. We focus on powerful probes such as neutrons and synchrotron X-ray radiation, which have become increasingly familiar to the electrochemical community. After discussing the general benefits (and drawbacks) of these characterization techniques and the work of customization required to adapt standard electrochemical cells to an operando diffraction experiment, we highlight several very recent results. We concentrate on important electrode materials such as the spinels Li1 + xMn2 - xO4 (0 ≤ x ≤ 0.10) and LiNi0.4Mn1.6O4. Thorough investigations led by operando neutron powder diffraction demonstrated that neutrons are highly sensitive to structural parameters that cannot be captured by other means (for example, atomic Debye-Waller factors and lithium site occupancy). Synchrotron radiation X-ray powder diffraction reveals how LiMn2O4 is subject to irreversibility upon the first electrochemical cycle, resulting in severe Bragg peak broadening. Even more interestingly, we show for the first time an ordering scheme of the elusive composition Li0.5Mn2O4, through the coexistence of Mn(3+):Mn(4+) 1:3 cation ordering and lithium/vacancy ordering. More accurately written as Li0.5Mn(3+)0.5Mn(4+)1.5O4, this intermediate phase loses the Fd\\overline 3m symmetry, to be correctly described in the P213 space group. PMID:26634725

  9. On the role of thermal backbone fluctuations in myoglobin ligand gate dynamics

    NASA Astrophysics Data System (ADS)

    Krokhotin, Andrey; Niemi, Antti J.; Peng, Xubiao

    2013-05-01

    We construct an energy function that describes the crystallographic structure of sperm whale myoglobin backbone. As a model in our construction, we use the Protein Data Bank entry 1ABS that has been measured at liquid helium temperature. Consequently, the thermal B-factor fluctuations are very small, which is an advantage in our construction. The energy function that we utilize resembles that of the discrete nonlinear Schrödinger equation. Likewise, ours supports topological solitons as local minimum energy configurations. We describe the 1ABS backbone in terms of topological solitons with a precision that deviates from 1ABS by an average root-mean-square distance, which is less than the experimentally observed Debye-Waller B-factor fluctuation distance. We then subject the topological multi-soliton solution to extensive numerical heating and cooling experiments, over a very wide range of temperatures. We concentrate in particular to temperatures above 300 K and below the Θ-point unfolding temperature, which is around 348 K. We confirm that the behavior of the topological multi-soliton is fully consistent with Anfinsen's thermodynamic principle, up to very high temperatures. We observe that the structure responds to an increase of temperature consistently in a very similar manner. This enables us to characterize the onset of thermally induced conformational changes in terms of three distinct backbone ligand gates. One of the gates is made of the helix F and the helix E. The two other gates are chosen similarly, when open they provide a direct access route for a ligand to reach the heme. We find that out of the three gates we investigate, the one which is formed by helices B and G is the most sensitive to thermally induced conformational changes. Our approach provides a novel perspective to the important problem of ligand entry and exit.

  10. Vibrational dynamics and band structure of methyl-terminated Ge(111)

    NASA Astrophysics Data System (ADS)

    Hund, Zachary M.; Nihill, Kevin J.; Campi, Davide; Wong, Keith T.; Lewis, Nathan S.; Bernasconi, M.; Benedek, G.; Sibener, S. J.

    2015-09-01

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD3-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH3-Ge(111) and CH3-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers.

  11. Vibrational dynamics and band structure of methyl-terminated Ge(111).

    PubMed

    Hund, Zachary M; Nihill, Kevin J; Campi, Davide; Wong, Keith T; Lewis, Nathan S; Bernasconi, M; Benedek, G; Sibener, S J

    2015-09-28

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD3-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH3-Ge(111) and CH3-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers. PMID:26429030

  12. Validation of reference genes for normalization of qPCR gene expression data from Coffea spp. hypocotyls inoculated with Colletotrichum kahawae

    PubMed Central

    2013-01-01

    Background Coffee production in Africa represents a significant share of the total export revenues and influences the lives of millions of people, yet severe socio-economic repercussions are annually felt in result of the overall losses caused by the coffee berry disease (CBD). This quarantine disease is caused by the fungus Colletotrichum kahawae Waller and Bridge, which remains one of the most devastating threats to Coffea arabica production in Africa at high altitude, and its dispersal to Latin America and Asia represents a serious concern. Understanding the molecular genetic basis of coffee resistance to this disease is of high priority to support breeding strategies. Selection and validation of suitable reference genes presenting stable expression in the system studied is the first step to engage studies of gene expression profiling. Results In this study, a set of ten genes (S24, 14-3-3, RPL7, GAPDH, UBQ9, VATP16, SAND, UQCC, IDE and β-Tub9) was evaluated to identify reference genes during the first hours of interaction (12, 48 and 72 hpi) between resistant and susceptible coffee genotypes and C. kahawae. Three analyses were done for the selection of these genes considering the entire dataset and the two genotypes (resistant and susceptible), separately. The three statistical methods applied GeNorm, NormFinder, and BestKeeper, allowed identifying IDE as one of the most stable genes for all datasets analysed, and in contrast GADPH and UBQ9 as the least stable ones. In addition, the expression of two defense-related transcripts, encoding for a receptor like kinase and a pathogenesis related protein 10, were used to validate the reference genes selected. Conclusion Taken together, our results provide guidelines for reference gene(s) selection towards a more accurate and widespread use of qPCR to study the interaction between Coffea spp. and C. kahawae. PMID:24073624

  13. Lyso-glycosphingolipids mobilize calcium from brain microsomes via multiple mechanisms.

    PubMed Central

    Lloyd-Evans, Emyr; Pelled, Dori; Riebeling, Christian; Futerman, Anthony H

    2003-01-01

    Recently, we demonstrated that the GSL (glycosphingolipid), GlcCer (glucosylceramide), modulates Ca2+ release from intracellular stores and from microsomes by sensitizing the RyaR (ryanodine receptor), a major Ca2+-release channel of the endoplasmic reticulum, whereas the lyso derivative of GlcCer, namely GlcSph (glucosylsphingosine), induced Ca2+ release via a mechanism independent of the RyaR [Lloyd-Evans, Pelled, Riebeling, Bodennec, de-Morgan, Waller, Schiffmann and Futerman (2003) J. Biol. Chem. 278, 23594-23599]. We now systematically examine the mechanism by which GlcSph and other lyso-GSLs modulate Ca2+ mobilization from rat brain cortical and cerebellar microsomes. GlcSph, lactosylsphingosine and galactosylsphingosine all mobilized Ca2+, but at significantly higher concentrations than those required for GlcCer-mediated sensitization of the RyaR. GlcSph-induced Ca2+ mobilization was partially blocked by heparin, an inhibitor of the Ins(1,4,5) P3 receptor, and also partially blocked by thapsigargin or ADP, inhibitors of SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase), but completely blocked when both acted together. In contrast, neither lactosylsphingosine nor galactosylsphingosine had any effect on Ca2+ release via either the Ins(1,4,5) P3 receptor or SERCA, but acted as agonists of the RyaR. Finally, and surprisingly, all three lyso-GSLs reversed inhibition of SERCA by thapsigargin. We conclude that different lyso-GSLs modulate Ca2+ mobilization via different mechanisms, and discuss the relevance of these findings to the GSL storage diseases in which lyso-GSLs accumulate. PMID:12917012

  14. A unified description of crystalline-to-amorphous transitions

    SciTech Connect

    Lam, N.Q.; Okamoto, P.R.; Devanathan, R. |; Meshii, M.

    1993-07-01

    Amorphous metallic alloys can now be synthesized by a variety of solid-state processes demonstrating the need for a more general approach to crystalline-to-amorphous (c-a) transitions. By focusing on static atomic displacements as a measure of chemical and topological disorder, we show that a unified description of c-a transformations can be based on a generalization of the phenomenological melting criterion proposed by Lindemann. The generalized version assumes that melting of a defective crystal occurs whenever the sum of thermal and static mean-square displacements exceeds a critical value identical to that for melting of the defect-free crystal. This implies that chemical or topological disorder measured by static displacements is thermodynamically equivalent to heating, and therefore that the melting temperature of the defective crystal will decrease with increasing amount of disorder. This in turn implies the existence of a critical state of disorder where the melting temperature becomes equal to a glass-transition temperature below which the metastable crystal melts to a glass. The generalized Lindemann melting criterion leads naturally to an interpretation of c-a transformations as defect-induced, low-temperature melting of critically disordered crystals. Confirmation of this criterion is provided by molecular-dynamics simulations of heat-induced melting and of defect-induced amorphization of intermetallic compounds caused either by the production of Frenkel pairs or anti-site defects. The thermodynamic equivalence between static atomic disorder and heating is reflected in the identical softening effects which they have on elastic properties and also in the diffraction analysis of diffuse scattering from disordered crystals, where the effect of static displacements appears as an artificially-enlarged thermal Debye-Waller factor. Predictions of this new, unified approach to melting and amorphization are compared with available experimental information.

  15. Structural studies of photoinduced intramolecular electron transfer in cyclopentadienylnickelnitrosyl

    SciTech Connect

    Chen, L.X.; Bowman, M.K.; Wang, Zhiyu; Norris, J.R. |; Montano, P.A. |

    1994-03-01

    A structural study based on EXAFS, FTIR, and optical absorption spectroscopies has been conducted on a photogenerated, metastable state of cyclopentadienylnickelnitrosyl (CpNiNO) produced by a reversible photochemical reaction. The photogenerated, metastable state with distinctively different EXAFS, IR, and optical absorption spectra from those of the ground state molecules was created by irradiating the sample with the 365 nm line of a mercury lamp at 20K . At the same temperature, the reverse reaction was induced by irradiation with the 313 nm line from the mercury lamp. Based on the analysis of the EXAFS data, the photogenerated, metastable state of CpNiNO has undergone considerable nuclear rearrangements compared to its ground state. The nuclear movement is characterized by a 0.12{angstrom} elongation of Ni-N bond and by a bending of Ni-N-O. A shift of the N-O stretching frequency from 1824 to 1387 cm{sup {minus}1} was observed in the photoinduced reaction with 365 nm light, implying that a NO{sup {minus}} like species results from intramolecular electron transfer from Ni to NO. The changes in the absorption spectra for the same reaction showed reduced absorption of the 385 nm band and a newly generated broad band near IR region. Temperature dependence of the Debye-Waller factor of CpNiNO was in good agreement with the diatomic harmonic oscillator for the Ni-N bond, but deviated for the Ni-O and the Ni-C bonds. Based on the structures obtained from EXAFS, ZINDO calculations for both the ground state and the photogenerated, metastable state of CpNiNO reproduced the general features of the observed absorption spectra and qualitatively explained the wavelength dependence of the reaction. The calculated partial charges on each atom in the ground state and the photogenerated, metastable state of CpNiNO are consistent with intramolecular electron transfer upon photoexcitation by 365 nm light.

  16. Time-convolutionless mode-coupling theory near the glass transition-A recursion formula and its asymptotic solutions

    NASA Astrophysics Data System (ADS)

    Tokuyama, Michio

    2015-07-01

    The time-convolutionless mode-coupling theory (TMCT) equation for the intermediate scattering function fα(q , t) derived recently by the present author is analyzed mathematically and numerically, where α = c stands for a collective case and α = s for a self case. All the mathematical formulations discussed by Götze for the MCT equation are then shown to be directly applicable to the TMCT equation. Firstly, it is shown that similarly to MCT, there exists an ergodic to non-ergodic transition at a critical point, above which the long-time solution fα(q , t = ∞) , that is, the so-called Debye-Waller factor fα(q) , reduces to a non-zero value. The critical point is then shown to be definitely different from that of MCT. Secondly, it is also shown that there is a two-step relaxation process in a β stage near the critical point, which is described by the same two different power-law decays as those obtained in MCT. In order to discuss the asymptotic solutions, the TMCT equation is then transformed into a recursion formula for a cumulant function Kα(q , t) (= - ln [fα(q , t) ]) . By employing the same simplified model as that proposed by MCT, the simplified asymptotic recursion formula is then numerically solved for different temperatures under the initial conditions obtained from the simulations. Thus, it is discussed how the TMCT equation can describe the simulation results within the simplified model.

  17. Magnetic and structural properties of nanostructured Fe–20Al–2Cr powder mixtures

    SciTech Connect

    Zerniz, N.; Azzaza, S.; Chater, R.; Abbas, H.; Bououdina, M.; Bouchelaghem, W.

    2015-02-15

    Nanostructured Fe–20Al–2Cr (wt.%) powders have been prepared using high energy planetary ball-mill. Changes in structural, morphological and magnetic properties of the powders during mechanical alloying (MA) and during subsequent annealing have been examined by X-ray diffraction, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The observed structural and microstructural changes have been related to several processes occurring during MA. After MA, the material becomes significantly disordered and refines to nanoscale grain sizes (~ 14 nm). The obtained bcc α-Fe(Al,Cr) solid solution shows a ferromagnetic behavior. Upon subsequent annealing at 400 °C, α-Fe{sub 2}O{sub 3} and spinel oxides are formed at the surface of particles, while structural defects disappeared as Fe(Al,Cr) solid solution becomes more ordered and grain growth occurs. The saturation magnetization (Ms) shows lower values after annealing, attributed to the formation of metal oxides with low magnetic moment. - Graphical abstract: Display Omitted - Highlights: • Nanostructured Fe–Al–Cr powders were prepared by MA. • Careful analysis of the XRD patterns by using the Rietveld refinement • The lattice distortion is evidenced by the increase of both the lattice parameter and the static Debye Waller parameter. • Annealing at 400 °C stabilizes the microstructure at the nanometer range and leads to the formation of Fe{sub 3}O{sub 4} and Fe{sub 2}O{sub 3} oxides. • Both the milled and annealed samples are ferromagnetic.

  18. Local structure study of (In{sub 0.95−x}Fe{sub x}Cu{sub 0.05}){sub 2}O{sub 3} thin films using x-ray absorption spectroscopy

    SciTech Connect

    Ren, Yuan; Xing, Yaya; Ma, Guanxiong; Wang, Shiqi; An, Yukai Liu, Jiwen; Zhao, Xingliang

    2015-07-15

    The (In{sub 0.95−x}Fe{sub x}Cu{sub 0.05}){sub 2}O{sub 3} (x = 0.06, 0.08, 0.15, and 0.20) films prepared by RF-magnetron sputtering were investigated by the combination of x-ray absorption spectroscopy (XAS) at Fe, Cu, and O K-edge. Although the Fe and O K-edge XAS spectra show that the Fe atoms substitute for the In sites of In{sub 2}O{sub 3} lattice for all the films, the Cu K-edge XAS spectra reveal that the codoped Cu atoms are separated to form the Cu metal clusters. After being annealed in air, the Fe atoms are still substitutionally incorporated into the In{sub 2}O{sub 3} lattice, while the Cu atoms form the CuO secondary phases. With the increase of Fe concentration, the bond length R{sub Fe-O} shortens and the Debye–Waller factor σ{sup 2}{sub Fe-O} increases in the first coordination shell of Fe, which are attributed to the relaxation of oxygen environment around the substitutional Fe ions. The forming of Cu relating secondary phases in the films is due to high ionization energy of Cu atoms, leading that the Cu atoms are energetically much harder to be oxidized to substitute for the In sites of In{sub 2}O{sub 3} lattice than Fe atoms. These results provide new experimental guidance in the preparation of the codoped In{sub 2}O{sub 3} based dilute magnetic oxides.

  19. Water-level altitudes 2006 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2005 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    USGS Publications Warehouse

    Kasmarek, Mark C.; Houston, Natalie A.; Brown, Dexter W.

    2006-01-01

    This report is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The Houston-Galveston region comprises Harris, Galveston, Fort Bend, Waller, and Montgomery Counties and adjacent parts of Brazoria, Grimes, Walker, San Jacinto, Liberty, and Chambers Counties. The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District. For the Chicot and Evangeline aquifers, maps show approximate water-level altitudes in 2006, water-level changes from 2005 to 2006, and approximate water-level changes from 2001 to 2006, from 1990 to 2006, and from 1977 to 2006 (figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10). For the Jasper aquifer, maps show approximate water-level altitudes in 2006 and water-level changes from 2005 to 2006 and 2000 to 2006 (figs. 11, 12, 13). The report also contains a map showing borehole extensometer (well equipped with compaction monitor) site locations (fig. 14) and graphs showing measured compaction of subsurface material at these sites from 1973 or later to 2005 (fig. 15).The U.S. Geological Survey (USGS) has published annual reports of water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region since 1979; and annual reports of same for the Fort Bend subregion (Fort Bend County and adjacent areas) since 1990. The USGS published its first water-level-altitude map for the Jasper aquifer in the greater Houston area (primarily Montgomery County) in 2001. The 2006 water-level-altitude and water-level-change maps for the three aquifers are included in this report.

  20. Experimental and theoretical study of rotationally inelastic diffraction of H2(D2) from methyl-terminated Si(111).

    PubMed

    Nihill, Kevin J; Hund, Zachary M; Muzas, Alberto; Díaz, Cristina; Del Cueto, Marcos; Frankcombe, Terry; Plymale, Noah T; Lewis, Nathan S; Martín, Fernando; Sibener, S J

    2016-08-28

    Fundamental details concerning the interaction between H2 and CH3-Si(111) have been elucidated by the combination of diffractive scattering experiments and electronic structure and scattering calculations. Rotationally inelastic diffraction (RID) of H2 and D2 from this model hydrocarbon-decorated semiconductor interface has been confirmed for the first time via both time-of-flight and diffraction measurements, with modest j = 0 → 2 RID intensities for H2 compared to the strong RID features observed for D2 over a large range of kinematic scattering conditions along two high-symmetry azimuthal directions. The Debye-Waller model was applied to the thermal attenuation of diffraction peaks, allowing for precise determination of the RID probabilities by accounting for incoherent motion of the CH3-Si(111) surface atoms. The probabilities of rotationally inelastic diffraction of H2 and D2 have been quantitatively evaluated as a function of beam energy and scattering angle, and have been compared with complementary electronic structure and scattering calculations to provide insight into the interaction potential between H2 (D2) and hence the surface charge density distribution. Specifically, a six-dimensional potential energy surface (PES), describing the electronic structure of the H2(D2)/CH3-Si(111) system, has been computed based on interpolation of density functional theory energies. Quantum and classical dynamics simulations have allowed for an assessment of the accuracy of the PES, and subsequently for identification of the features of the PES that serve as classical turning points. A close scrutiny of the PES reveals the highly anisotropic character of the interaction potential at these turning points. This combination of experiment and theory provides new and important details about the interaction of H2 with a hybrid organic-semiconductor interface, which can be used to further investigate energy flow in technologically relevant systems. PMID:27586939

  1. Bayes-Turchin Analysis of Overlapping L-Edges EXAFS Data of Iron

    NASA Astrophysics Data System (ADS)

    Rossner, H. H.; Schmitz, D.; Imperia, P.; Krappe, H. J.; Rehr, J. J.

    2007-02-01

    Spin polarized and spin averaged extended x-ray absorption fine structure ((M)EXAFS) data were measured at temperatures of 180 K and 296 K in the soft x-ray energy regime of the overlapping L-edges of an iron film grown on V(110). The absorption coefficients were analyzed with the Bayes-Turchin procedure. The analysis yields the correction function to the atomic-like background-absorption coefficient calculated by FEFF8 and reveals components of atomic EXAFS oscillations. The EXAFS Debye-Waller (DW) parameters were determined. Their split into a thermal and a structural contribution was not possible without theoretical input since the two temperatures in this experiment were not sufficiently far apart from each other and the k range of the data was too small. The a priori values of the thermal contribution to the DW parameters were therefore derived from a force-field model with two spring constants. They were adjusted to DW parameters calculated from Born-von Karman force constants which had been obtained from inelastic neutron scattering. Those two spring constants also nicely reproduce the unprojected vibrational density of states deduced from phonon dispersion curves. The MEXAFS oscillations can be described by the rigid-band model and the L2- and L3-EXAFS components. A negative exchange-related energy is obtained by fitting the MEXAFS signal in the extended energy region. This is in contrast to the predictions of the Hedin-Lundquist functional and the Dirac-Hara functional used in the FEFF8 code.

  2. Surface and bulk absorption characteristics of chemically vapor-deposited zinc selenide in the infrared.

    PubMed

    Klein, C A; Miller, R P; Stierwalt, D L

    1994-07-01

    Chemically vapor-deposited zinc selenide exhibits outstanding properties in the infrared and has been established as a prime material for transmissive optics applications. Here we present and discuss data relating to the surface and the bulk absorption forward-looking infrared- (FLIR-) grade chemically vapor-deposited ZnSe, at wavelengths (2-20 µm) and temperatures (100-500 K) of current interest.

    This investigation is based on both spectral emittance measurements and infrared transmission spectroscopy performed in the context of a systems development program. Surface effects can be detected at wavelengths of up to 14 µm and usually predominate at wavelengths of less than 8 µm. Fractional surface absorptions are temperature independent from approximately 200 to 400 K and can be fitted to a Fourier series, at wavelengths ranging from 3.5 to 13.5 µm. The bulk absorption coefficient (βv) is strongly dependent on temperature as well as wavelength, but it can be approximated by a bivariate polynomial expressin that yields recommended values. At wavelengths λ ≲ 10 µm, βv decreases with increasing temperature; it is shown that a wavelength-independent Debye-Waller factor provides a correct description of the temperature dependence, thus pointing to infrared-active localized modes. At wavelengths λ ≳ 14 µm, βv increases with temperature and exhibits temperature dependencies (T(1.7), T(2.6)) that reflect three- and four-phonon summation processes. Finally, an analysis of the temperature dependence of βv at 10.6 µm demonstrates that the intrinsic lattice dynamical contribution to bulk absorption at this wavelength should be close to 4 × 10(-4) cm(-1), in accord with the results of earlier laser calorimetry tests performed on exceptionally pure laser-grade chemically vapor-deposited ZnSe.

    PMID:20935788

  3. Vibrational dynamics and band structure of methyl-terminated Ge(111)

    SciTech Connect

    Hund, Zachary M.; Nihill, Kevin J.; Sibener, S. J.; Campi, Davide; Bernasconi, M.; Wong, Keith T.; Lewis, Nathan S.; Benedek, G.

    2015-09-28

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD{sub 3}-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH{sub 3}-Ge(111) and CH{sub 3}-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers.

  4. Vibration modes of a two-dimensional Wigner lattice coupled to ripplons on a liquid-helium surface

    NASA Astrophysics Data System (ADS)

    Eguiluz, A. G.; Maradudin, A. A.; Elliott, R. J.

    1981-07-01

    We present a theory of the vibration modes of a two-dimensional Wigner lattice coupled to ripplons on a liquid-helium surface based on the use of thermodynamic Green's functions. Starting from the phonon-ripplon Hamiltonian proposed by Fisher, Halperin, and Platzman, the effects of the electron-ripplon interaction (and hence the effects of the temperature and pressing electric field) on the frequencies of the coupled phonon-ripplon modes are obtained from the poles of the Green's function for the phonons of the Wigner lattice. The nature of these poles is determined by the phonon self-energy, which clearly displays the resonant coupling between the phonons and the ripplons. Our theory gives a first-principles derivation of the weights of the ripplon-induced resonances. We present approximate analytical results for the frequencies of the coupled modes. Our results are in qualitative agreement with the experiments of Grimes and Adams and the theory of Fisher et al. However, we do not find justification for the quantitative agreement with experiment that has been reported by Fisher et al. This discrepancy has to do with the fact that we show that the aforementioned weights are not given in terms of an effective Debye-Waller factor for the 2D Wigner lattice, but rather in terms of an exponential whose argument originates from the difference in electron displacement correlation functions given by .u-->(l1t1)q-->.u-->(l2t2)>-<(q-->.u-->)2>. This being the case, the normal modes of the phonon-ripplon Hamiltonian have frequencies whose values are somewhat smaller than the frequencies of the resonances measured by Grimes and Adams.

  5. EXAFS Studies and Microwave Magnetic Properties of FeGaB Thin Films and FeCuZr Ball-Milled Alloys

    NASA Astrophysics Data System (ADS)

    Gao, Jinsheng

    X-ray absorption fine structure (XAFS) is a spectroscopic technique which can investigate the physical and chemical structure of materials at the atomic scale. X-rays are applied in this technique to be near and above the binding energy of a particular core electronic level of a particular atomic species. Over the last decades, XAFS has emerged as a highly informative probe of the local structure around selected atomic species in solids, liquids, and molecular gases. It offers both element specificity and local structure sensitivity. Foremost among its strengths are its ability to probe the local atomic environments of different elements in the sample by selecting the corresponding incident X-ray energy. In the first part of this thesis, FeGaB alloys, which are of value as soft magnetic materials having relatively large magnetostriction coefficient, were fabricated in which varying amounts of boron were added to the host FeGa alloy to investigate its impact upon local atomic structure and magnetic and microwave properties. The impact of B upon the local atomic structure in FeGaB films were investigated by extended X-ray absorption fine structure (EXAFS) analysis. EXAFS fitting results revealed a contraction of lattice parameters with the introduction of B. The Debye-Waller factor determined from EXAFS fitting gradually increases as a function of boron addition and abruptly increases during the structural evolution from crystalline to amorphous. Upon the onset of this transition the static and microwave magnetic properties became exceptionally softer, with values of coercivity and ferromagnetic linewidth reducing dramatically. In the second part of this thesis, metastable alloys of the composition FeCuZr were synthesized by high energy ball milling and measured by EXAFS . The fitting results demonstrate that nanocrystalline or amorphous alloys have been obtained depending on the Zr content.

  6. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Not Available

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  7. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    SciTech Connect

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.

  8. Metastable NAT in Ice-Clouds

    NASA Astrophysics Data System (ADS)

    Weiss, Fabian; Kubel, Frank; Gálvez, Óscar; Hoelzel, Markus; Parker, Stewart F.; Iannarelli, Riccardo; Rossi, Michel J.; Grothe, Hinrich

    2015-04-01

    Polar Stratospheric Clouds and Cirrus Clouds contain, besides pure water ice, a rather large fraction of various hydrates. These are very important for the formation of the cloud, which is a yet not well understood process. We recently solved the structure of a metastable NAT phase (alpha-NAT), we believe to not only be present, but playing a major role in the formation of clouds. On the basis of previous work on this phase by Grothe et al. [1], we enhanced the production of alpha-NAT to the point, where we could produce enough sample to do neutron diffraction. This enabled us to solve the structure. Our quantum mechanical calculations, using this newly found structure, show a large affinity towards water-ice. With this in mind, we interlaced our results with the experiments of R. Iannarelli [2] to derive a new 3-step NAT-formation mechanism in ice-clouds, which could explain some of the observed kinetics better than the mechanism postulated in Zondlo et al. [3]. 1. Grothe, H., Tizek, H., Waller, D. & Stokes, D. The crystallization kinetics and morphology of nitric acid trihydrate. Phys. Chem. Chem. Phys., 8, 2232-2239 (2006) 2. Iannarelli, R. Multidiagnostic Observations on HCl and HNO3 Hydrate Films in the Temperature Range 170-205K: A Kinetic Study. PhD Thesis 21791, ETH Zürich, (2013). 3. Zondlo, M.A., Hudson, P.K., Prenni A.J. & Tolbert, M.A. Chemistry and microphysics of polar stratospheric clouds and Cirrus clouds. Ann. Rev. Phys. Chem., 51, 473-499 (2000).

  9. Influence of chemical substitution on the photoluminescence of Sr{sub (1−x)}Pb{sub x}WO{sub 4} solid solution

    SciTech Connect

    Hallaoui, A.; Taoufyq, A.; Arab, M.; Bakiz, B.; Benlhachemi, A.; Bazzi, L.; Villain, S.; Valmalette, J-C.; Guinneton, F.; Gavarri, J-R.

    2015-07-15

    The solid solution Sr{sub 1−x}Pb{sub x}WO{sub 4} based on luminescent tungstates SrWO{sub 4} and PbWO{sub 4} has been synthesized by solid-state reaction for all compositions 0≤x≤1. Using Rietveld method, the structural data of all polycrystalline samples have been refined and crystal cell parameters exhibited a linear behavior as a function of x. All substituted structures are of scheelite type. Scanning electron microscopy showed that a high level of crystallization characterized the samples, with modifications in sizes and shapes depending on composition x. Infrared and Raman spectroscopy have been performed to characterize the evolution of vibrational modes with substitution rate. Finally, a systematic study of luminescence under X-ray excitation has been performed: in the composition range x=0.2 to 0.4, intensities of emission exhibited increased values. The luminescence profiles have been interpreted in terms of four Gaussian components, two of them depending on substitution rate. - Graphical abstract: Photoluminescence under X-ray excitation of Sr{sub 1−x}Pb{sub x}WO{sub 4} solid solution: (left) decomposition of emission large band into four components for composition x=0.3; (right) variation of total emission intensity with composition x. - Highlights: • Structural study of solid solution Sr{sub 1−x}Pb{sub x} WO{sub 4} using Rietveld analyses. • Variation of Debye–Waller factor with composition x, disorder parameter. • Existence of four components of luminescence under X-ray excitation. • Effect of substitution of Sr by Pb on two components, due to Pb–O–W interactions. • Enhancement of luminescence intensity in a specific composition range.

  10. Silver Valence and Local Environments in Borosilicate and Calcium Aluminoborate Waste Glasses as determined from X-ray Absorption Spectroscopy

    SciTech Connect

    McKeown,D.; Gan, H.; Pegg, I.

    2005-01-01

    Silver K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data were collected and analyzed to characterize silver (Ag) environments in borosilicate and Ca-aluminoborate glass formulations developed as potential candidates for the immobilization of certain nuclear wastes. Silver is found in some nuclear waste streams and must be encapsulated in glass during waste vitrification processes. A related concern deals with phase separation within these glasses and whether colloidal silver would be present in the glass melt, which could present processing issues, or in the waste glass product. Characterization of the silver environments provides useful information for optimizing the silver incorporation ability of such glasses. Data were also gathered on four crystalline standards: Ag-foil, Ag{sub 2}O, argentojarosite (AgFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}), and AgO. XANES data indicate Ag{sup +} as the dominant species in the glasses. XANES and EXAFS data show that the average Ag environment in the Ca-aluminoborate glass is different compared with those in the two borosilicate glasses investigated. EXAFS analyses show that Ag in the borosilicate glasses is coordinated by two oxygens in a similar environment to that in crystalline Ag{sub 2}O, except that the associated Ag-O distances are approximately 0.10 Angstroms longer in the glass. Silver in the Ca-aluminoborate glass may be within one highly disordered site, or possibly, several different sites, where the average Ag-O distance, coordination number, and Debye-Waller factor are larger than those determined for the borosilicate glasses. Despite their relatively high silver contents, there is no evidence from XANES or EXAFS of colloidal silver in the glasses investigated.

  11. Editorial: Focus on Laser- and Beam-Driven Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Joshi, Chan; Malka, Victor

    2010-04-01

    , S Mangles, L O Silva, R Fonseca and P A Norreys Electro-optic shocks from blowout laser wakefields D F Gordon, A Ting, M H Helle, D Kaganovich and B Hafizi Onset of self-steepening of intense laser pulses in plasmas J Vieira, F Fiúza, L O Silva, M Tzoufras and W B Mori Analysis of laser wakefield dynamics in capillary tubes N E Andreev, K Cassou, F Wojda, G Genoud, M Burza, O Lundh, A Persson, B Cros, V E Fortov and C-G Wahlstrom Characterization of the beam loading effects in a laser plasma accelerator C Rechatin, J Faure, X Davoine, O Lundh, J Lim, A Ben-Ismaïl, F Burgy, A Tafzi, A Lifschitz, E Lefebvre and V Malka Energy gain scaling with plasma length and density in the plasma wakefield accelerator P Muggli, I Blumenfeld, C E Clayton, F J Decker, M J Hogan, C Huang, R Ischebeck, R H Iverson, C Joshi, T Katsouleas, N Kirby, W Lu, K A Marsh, W B Mori, E Oz, R H Siemann, D R Walz and M Zhou Generation of tens of GeV quasi-monoenergetic proton beams from a moving double layer formed by ultraintense lasers at intensity 1021-1023Wcm-2 Lu-Le Yu, Han Xu, Wei-Min Wang, Zheng-Ming Sheng, Bai-Fei Shen, Wei Yu and Jie Zhang Carbon ion acceleration from thin foil targets irradiated by ultrahigh-contrast, ultraintense laser pulses D C Carroll, O Tresca, R Prasad, L Romagnani, P S Foster, P Gallegos, S Ter-Avetisyan, J S Green, M J V Streeter, N Dover, C A J Palmer, C M Brenner, F H Cameron, K E Quinn, J Schreiber, A P L Robinson, T Baeva, M N Quinn, X H Yuan, Z Najmudin, M Zepf, D Neely, M Borghesi and P McKenna Numerical modelling of a 10-cm-long multi-GeV laser wakefield accelerator driven by a self-guided petawatt pulse S Y Kalmykov, S A Yi, A Beck, A F Lifschitz, X Davoine, E Lefebvre, A Pukhov, V Khudik, G Shvets, S A Reed, P Dong, X Wang, D Du, S Bedacht, R Zgadzaj, W Henderson, A Bernstein, G Dyer, M Martinez, E Gaul, T Ditmire and M C Downer Effects of laser prepulses on laser-induced proton generation D Batani, R Jafer, M Veltcheva, R Dezulian, O Lundh, F Lindau, A

  12. On Hilbert-Huang Transform Based Synthesis of a Signal Contaminated by Radio Frequency Interference or Fringes

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Shiri, Ron S.; Vootukuru, Meg; Coletti, Alessandro

    2015-01-01

    Norden E. Huang et al. had proposed and published the Hilbert-Huang Transform (HHT) concept correspondently in 1996, 1998. The HHT is a novel method for adaptive spectral analysis of non-linear and non-stationary signals. The HHT comprises two components: - the Huang Empirical Mode Decomposition (EMD), resulting in an adaptive data-derived basis of Intrinsic Mode functions (IMFs), and the Hilbert Spectral Analysis (HSA1) based on the Hilbert Transform for 1-dimension (1D) applied to the EMD IMF's outcome. Although paper describes the HHT concept in great depth, it does not contain all needed methodology to implement the HHT computer code. In 2004, Semion Kizhner and Karin Blank implemented the reference digital HHT real-time data processing system for 1D (HHT-DPS Version 1.4). The case for 2-Dimension (2D) (HHT2) proved to be difficult due to the computational complexity of EMD for 2D (EMD2) and absence of a suitable Hilbert Transform for 2D spectral analysis (HSA2). The real-time EMD2 and HSA2 comprise the real-time HHT2. Kizhner completed the real-time EMD2 and the HSA2 reference digital implementations respectively in 2013 & 2014. Still, the HHT2 outcome synthesis remains an active research area. This paper presents the initial concepts and preliminary results of HHT2-based synthesis and its application to processing of signals contaminated by Radio-Frequency Interference (RFI), as well as optical systems' fringe detection and mitigation at design stage. The Soil Moisture Active Passive (SMAP mission (SMAP) carries a radiometer instrument that measures Earth soil moisture at L1 frequency (1.4 GHz polarimetric - H, V, 3rd and 4th Stokes parameters). There is abundant RFI at L1 and because soil moisture is a strategic parameter, it is important to be able to recover the RFI-contaminated measurement samples (15% of telemetry). State-of-the-art only allows RFI detection and removes RFI-contaminated measurements. The HHT-based analysis and synthesis facilitates

  13. Laboratory investigations on hydrate formation and dissociation in sediments - analogies and differences to natural systems

    NASA Astrophysics Data System (ADS)

    Schicks, J. M.; Spangenberg, E.; Priegnitz, M.; Heeschen, K. U.; Thaler, J.; Abendroth, S.

    2014-12-01

    this contribution we present the experimental set up and discuss the results with regard to the analogies and differences to natural systems. [1] Jürgen Mienert, Maarten Vanneste, Stefan Bünz, Karin Andreassen, Haflidi Haflidason, Hans Petter Sejrup, Marine and Petroleum Geology 22 (2005) 233-244.

  14. Sizes and Albedos of Young C-type Asteroids

    NASA Astrophysics Data System (ADS)

    Tamblyn, Peter; Chapman, Clark; Durda, Dan; Merline, William; Nesvorny, David

    2005-06-01

    We propose to measure the sizes and albedos of 8 very young C-type asteroids with IRAC 8um and near-simultaneous ground-based visible photometry. Asteroid families are created from major collisions between asteroids and are identified from clustering of orbital elements. Co-I Nesvorny has recently identified an exceptionally-young family (Veritas) and precisely-dated it at only 8.3+/-0.5 Myr (just 0.2% of the age of the solar system). We will compare our results for this family with those obtained by our similar Spitzer GO-1 program where we study an even younger S-type family, Karin. C-type asteroids are composed of primitive material (as opposed to the more processed silicate-rich S-types) and comprise the majority of asteorids in the Main Belt, yet their compositions and properties remain elusive. These recent breakup events provide unparalleled opportunities to study compositions, dynamics, and collisions of asteroids. They allow tests of the rates of physical processes that happen on time scales comparable with the family age. Space weathering, for example, appears to affect C- and S-type asteroids very differently. We will test directly whether the Veritas fragments have similar albedos; we will also test if their albedos differ from those of similar asteroids with much older surfaces by study of a second C-type family, Themis. We will compare our observations with those made of larger asteroids of both families, from a companion ground-based program. We will quantify any correlation of size with albedo, a dominant uncertainty in standard size estimates. The size distribution will be used to calibrate hydrocode models of asteroid collisions. To do this will require observations at the smallest practical sizes. In addition, the measured sizes will be immediately applicable to a novel measurement of the Yarkovsky Effect. We have already demonstrated in our GO-1 program that we can make similar Spitzer observations and provide the ground-based visible support.

  15. Predicting polarization and nonlinear dielectric response of arbitrary perovskite superlattice sequences

    NASA Astrophysics Data System (ADS)

    Wu, Xifan

    2008-03-01

    A complete theory of epitaxial perovskite superlattices requires an understanding both of epitaxial strain effects and of electrostatic boundary conditions. Here, focusing on the latter issue, weootnotetextIn collaboration with Massimiliano Stengel, Karin M. Rabe and David Vanderbilt. have carried out first-principles calculations of the nonlinear dielectric properties of short-period ``bicolor'' and ``tricolor'' CaTiO3/SrTiO3/BaTiO3 superlattices having the in-plane lattice constant of SrTiO3. In particular, we have calculated the layer polarizations pj as defined using the Wannier-based method of Wu, Di'eguez, Rabe and VanderbiltootnotetextX. Wu, O. Di'eguez, K. Rabe and D. Vanderbilt, Phys. Rev. Lett. 97, 107602 (2006). for each neutral BaO, SrO, CaO, or TiO2 layer. We use a cluster expansion (CE) technique to model the layer polarizations pj of a selected set of bicolor superlattices as a function of the displacement field D (which is uniform throughout the insulating superlattice), the chemical identity of the layer itself, and the chemical identity of its neighboring layers. We find that pj is a strongly localized function of its chemical environments at fixed D field, i.e., the dependence on the identity of the neighboring layers decays rapidly with distance. This localized property enables us to arrive at a truncated and simplified CE model which can accurately predict pj(D) in arbitrary layer sequences, both bicolor and tricolor. A similar approach is used to model the dependence of the c lattice constant. With all this information in hand, we can predict the polarization, piezoelectric and nonlinear dielectric response of arbitrary superlattice sequences. The power of the approach is demonstrated by showing that a model fitted only to calculations on inversion-symmetric bi-color superlattices can successfully predict the inversion symmetry breaking in tricolor superlattices such as 2SrTiO3/1BaTiO3/1CaTiO3.

  16. Defining the Flora Family: Orbital properties, reflectance properties and age

    NASA Astrophysics Data System (ADS)

    Dykhuis, Melissa J.; Molnar, Lawrence; Van Kooten, Samuel J.; Greenberg, Richard

    2014-11-01

    The Flora family resides in the densely populated inner main belt, bounded in semimajor axis by the ν6 secular resonance and the Jupiter 3:1 mean motion resonance. The presence of several large families that overlap dynamically with the Floras (e.g., the Vesta, Baptistina, and Nysa-Polana families), and the removal of a significant fraction of Floras via the nearby ν6 resonance complicates the Flora family's distinction in both proper orbital elements and reflectance properties. Here we use orbital information from the Asteroids Dynamic Site (AstDyS), color information from the Sloan Digital Sky Survey (SDSS), and albedo information from the Wide-field Infrared Survey Explorer (WISE) to obtain the median orbital and reflectance properties of the Floras by sampling the core of the family in multidimensional phase space. We find the median Flora SDSS colors to be a∗ = 0.126 ± 0.007 and i -z =-0.037±0.007 ; the median Flora albedo is pV = 0.291 ± 0.012. These properties allow us to define ranges for the Flora family in orbital and reflectance properties, as required for a detailed dynamical study. We use the young Karin family, for which we have an age determined via direct backward integration of members' orbits, to calibrate the Yarkovsky drift rates for the Flora family without having to estimate the Floras' material properties. The size-dependent dispersion of the Flora members in semimajor axis (the "V" plot) then yields an age for the family of 950-170+200 My, with the uncertainty dominated by the uncertainty in the material properties of the family members (e.g., density and surface thermal properties). We discuss the effects on our age estimate of two independent processes that both introduce obliquity variations among the family members on short (My) timescales: (1) the capture of Flora members in spin-orbit resonance, and (2) YORP-driven obliquity variation through YORP cycles. Accounting for these effects does not significantly change this age

  17. Redetermination of the Space Weathering Rate Using Spectra of Iannini Asteroid Family Members

    NASA Astrophysics Data System (ADS)

    Willman, Mark; Jedicke, R.; Nesvorny, D.; Moskovitz, N.; Ivezic, Z.; Fevig, R.

    2007-12-01

    We have obtained moderate S/N ( 85) spectra at a realized resolution of R 100 for 11 members of the Iannini family, until recently the youngest known family at under 5 million years of age. The spectra were acquired using ESI in its low-resolution prism mode on the Keck II telescope. The family members belong to the S class of asteroids with perhaps some K class members. The Iannini family members's average spectral slope, the slope of the best-fit line constrained to pivot about 1 at 550 nm, is (0.30±0.04)/μm, matching that previously reported using SDSS color photometry. Using our spectra for this family as well as new observations of Karin family members and new classifications of some older families we revised the space weathering rate of S class asteroids. We parameterize the space weathering rate of the principal component color of the spectrum (PC1), which is correlated with the spectral slope, as PC1(t) = PC1(0) + Δ PC1[1 - \\exp^{-(t/κ)α}]. Our revised rate suggests that the characteristic time scale for space weathering is τ = 570 ± 220 Myr and that new S class clusters will have an initial color of PC1(0) = 0.31 ± 0.04. This rate is in better agreement with lab measurements, supporting the use of space weathering as a dating method. Under the assumption that all the spectra should be identical, since the members all derive from the same parent body and are presumably covered with similar regolith, we combined them to obtain a high-S/N composite spectrum for the family. While the combined spectrum is clearly within the S/K class we note the appearance of a 'green feature' near 550 nm that has not previously been identified in asteroid spectra. We tentatively identify it as a feature in the pyroxene spectra as observed in the lab.

  18. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA (Invited)

    NASA Astrophysics Data System (ADS)

    Soave, K.; Dean, A.; Darakananda, K.; Ball, O.; Butti, C.; Yang, G.; Vetter, M.; Grimaldi, Z.

    2009-12-01

    Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA Kathy Soave, Amy Dean, Olivia Ball, Karin Darakananda, Matt Vetter, Grant Yang, Charlotte Butti, Zoe Grimaldi The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects (A and B) and using randomly determined points within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will analyze the population densities, seasonal abundance and long-term population trends of key algal and invertebrate species. Future analyses and investigations will include intertidal abiotic factors (including water temperature and human foot-traffic) to enhance insights into the workings of the Duxbury Reef ecosystem, in particular, the high intertidal zone which experiences the greatest amount of human

  19. Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Reports included:Long Term Stability of Mars Trojans; Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits; Effect of Roughness on Visible Reflectance Spectra of Planetary Surface; SUBARU Spectroscopy of Asteroid (832) Karin; Determining Time Scale of Space Weathering; Change of Asteroid Reflectance Spectra by Space Weathering: Pulse Laser Irradiation on Meteorite Samples; Reflectance Spectra of CM2 Chondrite Mighei Irradiated with Pulsed Laser and Implications for Low-Albedo Asteroids and Martian Moons; Meteorite Porosities and Densities: A Review of Trends in the Data; Small Craters in the Inner Solar System: Primaries or Secondaries or Both?; Generation of an Ordinary-Chondrite Regolith by Repetitive Impact; Asteroid Modal Mineralogy Using Hapke Mixing Models: Validation with HED Meteorites; Particle Size Effect in X-Ray Fluorescence at a Large Phase Angle: Importance on Elemental Analysis of Asteroid Eros (433); An Investigation into Solar Wind Depletion of Sulfur in Troilite; Photometric Behaviour Dependent on Solar Phase Angle and Physical Characteristics of Binary Near-Earth-Asteroid (65803) 1996 GT; Spectroscopic Observations of Asteroid 4 Vesta from 1.9 to 3.5 micron: Evidence of Hydrated and/or Hydroxylated Minerals; Multi-Wavelength Observations of Asteroid 2100 Ra-Shalom: Visible, Infrared, and Thermal Spectroscopy Results; New Peculiarities of Cometary Outburst Activity; Preliminary Shape Modeling for the Asteroid (25143) Itokawa, AMICA of Hayabusa Mission; Scientific Capability of MINERVA Rover in Hayabusa Asteroid Mission; Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission; Sampling Strategy and Curation Plan of Hayabusa Asteroid Sample Return Mission; Visible/Near-Infrared Spectral Properties of MUSES C Target Asteroid 25143 Itokawa; Calibration of the NEAR XRS Solar Monitor; Modeling Mosaic Degradation of X-Ray Measurements of 433 Eros by NEAR-Shoemaker; Scattered Light Remediation and Recalibration of

  20. HSTOF ENA observations and energetic ion distributions in the heliosheath

    NASA Astrophysics Data System (ADS)

    Czechowski, A.; Hilchenbach, M.; Hsieh, K. C.

    2012-05-01

    caused by the charge-exchange and the escape losses. We dedicate this work to the memory of our longstanding coworker and dear colleague Karin Bamert.

  1. Proton-transfer dynamics in the hydrogen bond. Inelastic neutron scattering, infrared and Raman spectra of KH(CF 3COO) 2 and CsH(CF 3COO) 2

    NASA Astrophysics Data System (ADS)

    Fillaux, F.; Tomkinson, J.

    1991-12-01

    Inelastic neutron scattering (INS), infrared and Raman spectra of potassium and cesium hydrogen bistrifluoroacetate (KH(CF 3COO) 2 and CsH(CF 3COO) 2, respectively) at 20 K are reported. In both crystals H(CF 3COO) 2- centrosymmetric dimers are linked by strong hydrogen bonds, whose lengths are 2.435 and 2.38 Å, respectively. The principal OH modes appear at the same frequencies for both compounds. The OH stretching band shapes are similar in infrared and in INS. The submaxima are attributed to interactions with other internal modes. Below 200 cm -1, the cesium salt shows three narrow bands which emerge from the density-of-states. They are assigned to localized modes involving the proton. A sharp band at 87 cm -1 corresponds to the "tunnelling" transition in a quasi-symmetric double-minimum potential with a barrier height of 1340 cm -1. The other two narrow bands, at 36 and 49 cm -1, are assigned to the internal torsions of coupled CF 3COO groups. Potential barriers are estimated. A detailed band-shape analysis of the OH bending modes provides clear indications of different dynamics for the two salts. KH(CF 3COO) 2 is rather stiff and phonon wings involving the whole lattice density-of-states are observed for the δOH mode but not for the γOH mode. For this latter, the observed combinations indicate a dynamical coupling with the internal torsion. CsH(CF 3COO) 2 is rather soft and recoil occurs. The INS intensities of the OH bending modes are decreased by Debye-Waller factors and their frequencies are shifted upwards. The estimated masses of the recoiling particles are consistent with strong dynamical coupling of the γOH with the torsional mode on the one hand, and of the δOH with translational modes on the other. The polarizability of the counter ion appears to play a leading role in proton dynamics.

  2. XAFS study of gadolinium and samarium bisporphyrinate complexes.

    PubMed

    Agondanou, J H; Spyroulias, G A; Purans, J; Tsikalas, G; Souleau, C; Coutsolelos, A G; Bénazeth, S

    2001-11-19

    The comparative X-ray absorption spectroscopy study of gadolinium and samarium bisporphyrinate complexes represented by the formulas Gd(III)H(oep)(tpp), Gd(III)(oep)(2), Gd(III)H(tpp)(2) and Sm(III)H(oep)(tpp), Sm(III)(oep)(2), Sm(III)H(tpp)(2) is reported. The XAFS spectra are recorded on the LURE-DCI storage ring (Orsay, France) in transmission mode on the microcrystalline samples at the Gd and Sm L(3) edges. The local environment for Ln(3+) ions has been reconstructed applying one-shell and two-shell XAFS analysis procedures. The protonated and nonprotonated bisporphyrinate complexes present different XAFS features. After our analysis on the title derivatives, the gadolinium ion (at 80 K) is found to be bonded: (i) to eight nitrogen atoms at R(Gd-N) 2.50 A, for Gd(III)(oep)(2) [Debye-Waller (DW) factor 0.004 A(2)]; (ii) to seven nitrogen atoms at R(Gd-N) 2.49 A, for Gd(III)H(oep)(tpp) [DW factor 0.005 A(2)] and one nitrogen at long distance; and (iii) to six nitrogen atoms at R(Gd-N) 2.50 A [DW factor 0.006 A(2)] and two nitrogen atoms at long distance for Gd(III)H(tpp)(2). A similar coordination sphere has been detected for the corresponding Sm derivatives. So, the samarium ion (at room temperature) is bonded: (i) to eight nitrogen atoms at R(Sm-N) 2.53 A, for Sm(III)(oep)(2) [DW factor 0.006 A(2)]; (ii) to seven nitrogen atoms at R(Sm-N) 2.53 A, for Sm(III)H(oep)(tpp) [DW factor 0.006 A(2)] and one nitrogen at long distance; and (iii) to six nitrogen atoms at R(Sm-N) 2.50 A, for Sm(III)H(tpp)(2) [DW factor 0.006 A(2)] and two nitrogen atoms at long distance. As far as concerns Ln(III)(oep)(2) complexes, the increase of Ln-N distance in the series Gd(3+) < Eu(3+) < Sm(3+) reflects an increase in the ionic radii, which are in good agreement with previously published XRD data on Eu(III)(oep)(2). Moreover, the protonated Ln(III)H(oep)(tpp) and Ln(III)H(tpp)(2) complexes possess systematically shorter distances of about 0.02 A between the XAFS and XRD data. This

  3. Influence of Urbanicity and County Characteristics on the Association between Ozone and Asthma Emergency Department Visits in North Carolina

    PubMed Central

    Rappold, Ana G.; Davis, J. Allen; Richardson, David B.; Waller, Anna E.; Luben, Thomas J.

    2014-01-01

    Background: Air pollution epidemiologic studies, often conducted in large metropolitan areas because of proximity to regulatory monitors, are limited in their ability to examine potential associations between air pollution exposures and health effects in rural locations. Methods: Using a time-stratified case-crossover framework, we examined associations between asthma emergency department (ED) visits in North Carolina (2006–2008), collected by a surveillance system, and short-term ozone (O3) exposures using predicted concentrations from the Community Multiscale Air Quality (CMAQ) model. We estimated associations by county groupings based on four urbanicity classifications (representative of county size and urban proximity) and county health. Results: O3 was associated with asthma ED visits in all-year and warm season (April–October) analyses [odds ratio (OR) = 1.019; 95% CI: 0.998, 1.040; OR = 1.020; 95% CI: 0.997, 1.044, respectively, for a 20-ppb increase in lag 0–2 days O3]. The association was strongest in Less Urbanized counties, with no evidence of a positive association in Rural counties. Associations were similar when adjusted for fine particulate matter in copollutant models. Associations were stronger for children (5–17 years of age) compared with other age groups, and for individuals living in counties identified with poorer health status compared with counties that had the highest health rankings, although estimated associations for these subgroups had larger uncertainty. Conclusions: Associations between short-term O3 exposures and asthma ED visits differed by overall county health and urbanicity, with stronger associations in Less Urbanized counties, and no positive association in Rural counties. Results also suggest that children are at increased risk of O3-related respiratory effects. Citation: Sacks JD, Rappold AG, Davis JA Jr, Richardson DB, Waller AE, Luben TJ. 2014. Influence of urbanicity and county characteristics on the association

  4. Liquid-glass transition in charge-stabilized colloidal dispersions

    NASA Astrophysics Data System (ADS)

    Lai, S. K.; Wang, G. F.; Peng, W. P.

    2000-06-01

    We model the inter-colloidal interactions in a charge-stabilized colloidal dispersion by a hard-core Yukawa potential φ(r)=σ0γ exp(-κr)/r, r>σ0 and apply the rescaled mean spherical approximation to calculate its static structure factor. In conjunction with the idealized mode-coupling theory, we determine the loci of the liquid-glass transition phase boundary for a salt-free suspension of charged colloids evaluated at different counter-ion environment (characterized by the κ) in terms of the macro-ion parameters: volume fraction ɛ, charge Z0 and size σ0. The calculated parametric phase diagrams are quite general since the results, with slight and straightforward modification, can be utilized to study the glass transition in a more realistic colloidal solution such as an aqueous monodisperse suspension of polystyrene charged spheres with an added electrolyte. Confining our discussion, then, to the simplest salt-free colloidal liquids, we extract from our analysis of the calculated liquid-glass transition boundaries some succinct features. Specifically, we show in this work that given a range of interaction Vkgr=κσ0<~3.8, there is a possibility of observing the liquid⇋glass⇋liquid⇋glass(LGLG) re-entrant phenomenon in restrictive regions of the phase diagram ɛ-σ0 or ɛ-Z0 for a monodisperse charge-stabilized solution. However, as the σ0 increases above a critical size, the LGLG re-entrant behavior vanishes. To delve into this re-entrant phenomenon, we compare, for a given Vkgr, the glassy Debye-Waller factor, static structure factor and their spatial counterparts for two cases-nnone for lower-Z0 colloids at a high ɛ and the other for higher-Z0 colloids at a low ɛ. For the former, the glassification is basically driven by the geometric restriction while that, for the latter, it is mainly induced by the Coulomb force. We conclude from this comparison that under the same screening environment both the excluded volume and the electrostatic effects are

  5. X-ray studies of manganese doped III-V materials

    NASA Astrophysics Data System (ADS)

    Stuckey, Aaron M.

    Two x-ray techniques have been employed to study two classes of semiconductors. X-ray Absorption Fine-structure Spectroscopy (XAFS) was used to examine the Mn environment in the dilute magnetic semiconductors Ga1- xMnxAs and Ga1- x-yMnxBeyAs. X-ray reflectivity was used to characterize the structure of InMnAs heterostructures and InAlP oxide films. XAFS measurements of the Mn local environment were performed in order to match structural parameters such as coordination numbers, bond lengths, and XAFS Debye-Waller factors to the ferromagnetic properties of the materials. The Mn local environment in Ga1-xMn xAs materials with x = 0.01, 0.03, 0.05, and 0.08 was found to be that of a Mn ion substituting for a Ga ion in the GaAs lattice (MnGa). The Mn local environment of the Ga1- x-yMnxBe yAs materials was also measured for six samples with constant x = 0.05 and y = 0.0, 0.01, 0.03, 0.05, 0.08 and 0.11. The Mn local environment depended upon the concentration of Be in the material. At y = 0.0 and y = 0.01 the Mn local environment was found to be that of the MnGa site. The percentage of Mn in this local environment decreased as the Be concentration of the samples increased. Meanwhile, the percentage of Mn in an interstitial site and the percentage of Mn in a precipitate MnAs site both increased. No evidence of Mn-Mn or Mn-Be pairing was found in the Ga1- x-yMnxBeyAs materials. The x-ray reflectivity measurements were used to characterize the structure of InMnAs and InAlP in order to improve understanding of the structural characteristics. This improvement can then be used to improve the growth parameters in order to create materials upon which device development may be undertaken. The InMnAs materials were found to have a structure closely matching the expectations from growth with the addition of a low density surface film. The InAlP oxide films were found to have an additional layer at the interface between the substrate and the oxide film which has higher electron

  6. The old problems of glass and the glass transition, and the many new twists.

    PubMed Central

    Angell, C A

    1995-01-01

    In this paper I review the ways in which the glassy state is obtained both in nature and in materials science and highlight a "new twist"--the recent recognition of polymorphism within the glassy state. The formation of glass by continuous cooling (viscous slowdown) is then examined, the strong/fragile liquids classification is reviewed, and a new twist-the possibility that the slowdown is a result of an avoided critical point-is noted. The three canonical characteristics of relaxing liquids are correlated through the fragility. As a further new twist, the conversion of strong liquids to fragile liquids by pressure-induced coordination number increases is demonstrated. It is then shown that, for comparable systems, it is possible to have the same conversion accomplished via a first-order transition within the liquid state during quenching. This occurs in the systems in which "polyamorphism" (polymorphism in the glassy state) is observed, and the whole phenomenology is accounted for by Poole's bond-modified van der Waals model. The sudden loss of some liquid degrees of freedom through such weak first-order transitions is then related to the polyamorphic transition between native and denatured hydrated proteins, since the latter are also glass-forming systems--water-plasticized, hydrogen bond-cross-linked chain polymers (and single molecule glass formers). The circle is closed with a final new twist by noting that a short time scale phenomenon much studied by protein physicists-namely, the onset of a sharp change in d/dT ( is the Debye-Waller factor)--is general for glass-forming liquids, including computer-simulated strong and fragile ionic liquids, and is closely correlated with the experimental glass transition temperature. The latter thus originates in strong anharmonicity in certain components of the vibrational density of states, which permits the system to access the multiple minima of its configuration space. The connection between the anharmonicity

  7. Investigating the interfacial dynamics of thin films

    NASA Astrophysics Data System (ADS)

    Rosenbaum, Aaron W.

    surface specific nature of helium atom scattering allows for a deft study of the relationship between surface motion and the glass transition temperature. An added parameter in this complex organic system is the film thickness. The confinement effects and enhanced surface displacement were examined as a function of the thermal attenuation of both inelastic and elastic helium atom scattering. The Debye-Waller factor for these thin films of PMMA is similar to the low-density alkanethiol self-assembled monolayers discussed earlier.

  8. Starburst outflows from nearby galaxies

    NASA Technical Reports Server (NTRS)

    Waller, William H.

    1990-01-01

    Starburst outflows from NGC 5461, 1569 and M82 are discussed. The Sc I galaxy, M101, is reknowned for the kpc-size superassociations of star clusters and HII regions that dominate its spiral arms. NGC 5461 is one of the brightest of these superassociations, rivaling the Large Magellanic Cloud in H alpha luminosity. The NGC 5461 superassociation is dominated by a single unresolved HII region of outstanding luminosity (approx. 1000 Orion nebulae). Detailed examination of corresponding continuum images indicates that only the southern plume has any sort of stellar counterpart. The other plumes are clearly diffuse with no underlying hot stars. An image of NGC 1569 is discussed. Besides showing the peculiar arm noted by Zwicky (1971) and the filamentary extensions to the North and South (as noted by Hodge 1974), this image also reveals two arc-like features of diffuse ionized gas to the South. Both arcs are concentric with the bright center of the galaxy - where the super star clusters, A and B are located. The inner arc (Arc 1) appears to follow the same curve as the SW arm thus suggesting that the two features represent limb-brightened fragments of vast superbubble that was blown out by a central starburst sometime in the past. As the classic starburst galaxy, M82 displays all the luminous hallmarks of intense high-mass star formation and outflow activity. The diffuse H alpha and x ray emitting gas along the minor axis provides especially good evidence for a bipolar outflow of hot gas which is shock heating the swept-up interstellar medium (ISM) to temperatures of approx. 10(exp 4) K. An image shows the H alpha emission within the disk and along the minor axis. Another image shows the same field in the light of near-infrared. Both figures are based on charge coupled device images taken with the McGraw-Hill 1.3 m telescope (Waller 1989). The longer wavelength emission clearly shows a more extended morphology along the major axis. The morphological discrepancy is most

  9. X-ray absorption fine structure study of the effect of protonation on disorder and multiple scattering in phosphate solutions and solids.

    PubMed

    Rouff, Ashaki A; Rabe, Stefan; Nachtegaal, Maarten; Vogel, Frédéric

    2009-06-25

    Phosphorus K-edge X-ray absorption fine structure (XAFS) was explored as a means to distinguish between aqueous and solid phosphates and to detect changes in phosphate protonation state. Data were collected for H(3)PO(4), KH(2)PO(4), K(2)HPO(4) and K(3)PO(4) solids and solutions and for the more complex phosphates, hydroxylapatite (HAP) and struvite (MAP). The X-ray absorption near-edge structure (XANES) spectra for solid samples are distinguishable from those of solutions by a shoulder at approximately 4.5 eV above the edge, caused by scattering from cation sites. For phosphate species, the intensity of the white line peak increased for solid and decreased for aqueous samples, respectively, with phosphate deprotonation. This was assigned to increasing charge delocalization in solid samples, and the effect of solvating water molecules on charge for aqueous samples. In the extended X-ray absorption fine structure (EXAFS), backscattering from first-shell O atoms dominated the chi(k) spectra. Multiple scattering (MS) via a four-legged P-O(1)-P-O(1)-P collinear path was localized in the lower k region at approximately 3.5 A(-1) and contributed significantly to the beat pattern of the first oscillation. For EXAFS analysis, increasing Debye-Waller factors suggest more disorder in the P-O shell with addition of protons to the crystal structure due to the lengthening effects of P-OH bonds. This disorder produces splitting in the hybridized P 3p-O 2p band in the density of states. For aqueous samples, however, increased protonation reduced the structural disorder within this shell. This was linked to a change from kosmotropic to chaotropic behavior of the phosphate species, with reduced effects of H bonding on structural distortion. The intensity of MS is correlated to the degree of disorder in the P-O shell, with more ordered structures exhibiting enhanced MS. The observed trends in the XAFS data can be used to distinguish between phosphate species in both solid and

  10. Understanding the changes in ductility and Poisson's ratio of metallic glasses during annealing from microscopic dynamics

    SciTech Connect

    Wang, Z.; Ngai, K. L.; Wang, W. H.

    2015-07-21

    In the paper K. L. Ngai et al., [J. Chem. 140, 044511 (2014)], the empirical correlation of ductility with the Poisson's ratio, ν{sub Poisson}, found in metallic glasses was theoretically explained by microscopic dynamic processes which link on the one hand ductility, and on the other hand the Poisson's ratio. Specifically, the dynamic processes are the primitive relaxation in the Coupling Model which is the precursor of the Johari–Goldstein β-relaxation, and the caged atoms dynamics characterized by the effective Debye–Waller factor f{sub 0} or equivalently the nearly constant loss (NCL) in susceptibility. All these processes and the parameters characterizing them are accessible experimentally except f{sub 0} or the NCL of caged atoms; thus, so far, the experimental verification of the explanation of the correlation between ductility and Poisson's ratio is incomplete. In the experimental part of this paper, we report dynamic mechanical measurement of the NCL of the metallic glass La{sub 60}Ni{sub 15}Al{sub 25} as-cast, and the changes by annealing at temperature below T{sub g}. The observed monotonic decrease of the NCL with aging time, reflecting the corresponding increase of f{sub 0}, correlates with the decrease of ν{sub Poisson}. This is important observation because such measurements, not made before, provide the missing link in confirming by experiment the explanation of the correlation of ductility with ν{sub Poisson}. On aging the metallic glass, also observed in the isochronal loss spectra is the shift of the β-relaxation to higher temperatures and reduction of the relaxation strength. These concomitant changes of the β-relaxation and NCL are the root cause of embrittlement by aging the metallic glass. The NCL of caged atoms is terminated by the onset of the primitive relaxation in the Coupling Model, which is generally supported by experiments. From this relation, the monotonic decrease of the NCL with aging time is caused by the slowing down

  11. Taking centre stage...

    NASA Astrophysics Data System (ADS)

    1998-11-01

    HAMLET (Highly Automated Multimedia Light Enhanced Theatre) was the star performance at the recent finals of the `Young Engineer for Britain' competition, held at the Commonwealth Institute in London. This state-of-the-art computer-controlled theatre lighting system won the title `Young Engineers for Britain 1998' for David Kelnar, Jonathan Scott, Ramsay Waller and John Wyllie (all aged 16) from Merchiston Castle School, Edinburgh. HAMLET replaces conventional manually-operated controls with a special computer program, and should find use in the thousands of small theatres, schools and amateur drama productions that operate with limited resources and without specialist expertise. The four students received a £2500 prize between them, along with £2500 for their school, and in addition they were invited to spend a special day with the Royal Engineers. A project designed to improve car locking systems enabled Ian Robinson of Durham University to take the `Working in industry award' worth £1000. He was also given the opportunity of a day at sea with the Royal Navy. Other prizewinners with their projects included: Jun Baba of Bloxham School, Banbury (a cardboard armchair which converts into a desk and chair); Kobika Sritharan and Gemma Hancock, Bancroft's School, Essex (a rain warning system for a washing line); and Alistair Clarke, Sam James and Ruth Jenkins, Bishop of Llandaff High School, Cardiff (a mechanism to open and close the retractable roof of the Millennium Stadium in Cardiff). The two principal national sponsors of the competition, which is organized by the Engineering Council, are Lloyd's Register and GEC. Industrial companies, professional engineering institutions and educational bodies also provided national and regional prizes and support. During this year's finals, various additional activities took place, allowing the students to surf the Internet and navigate individual engineering websites on a network of computers. They also visited the

  12. Tektite 1, man-in-the-sea project: Marine Science Program

    USGS Publications Warehouse

    Clifton, H.E.; Mahnken, C.V.W.; Van Derwalker, J. C.; Waller, R.A.

    1970-01-01

    The Tektite experiment was designed to provide data for a number of behavioral, biomedical, and engineering studies in addition to the marine sciences program. Conditions for some of these studies were not altogether compatible with the program for the marine sciences. For example, isolation imposed by human behavioral studies precluded physical contact with the surface team, even though such contact was physically possible and desirable for the conduct of the marine sciences program. Isolation also imposed on the scientific team the duty of all in-habitat maintenance, both scheduled and unscheduled, thereby taking substantial time from scientific research. In addition, between 10 and 20 percent of the waking time was devoted to performance of psychological tests required for the biomedical studies. Most of the experiments were directed toward detecting potentially adverse changes and thus were accepted as necessary and desirable. The only health problem to affect the scientific program during the dive was a minor external ear infection contracted by all the divers. Nonetheless, the experiment demon. strated, at least to our satisfaction, the advantages of underwater habitation and saturation diving for biological and geological research. A major advantage is the opportunity for continuous monitoring of organisms or processes. In addition, underwater habitation provides for considerably more research time in the water than surface diving or intermittent bottom dwelling, and this advantage increases greatly as the depth of habitation increases. Even in the relatively shallow depths at which Tektite 1 was conducted, the undersea team could spend appreciably more time at work in the water than their colleagues on the surface. Finally, Tektite 1 demonstrated that the scientist who lives in the sea need not have the extensive qualifications of a professional diver. Of the four scientists of the in-habitat team, only Crew Chief Waller was so qualified; the other three

  13. Glassy Interfacial Dynamics of Ni Nanoparticles: Part II Discrete Breathers as an Explanation of Two-Level Energy Fluctuations

    PubMed Central

    Zhang, Hao; Douglas, Jack F.

    2012-01-01

    Recent studies of the dynamics of diverse condensed amorphous materials have indicated significant heterogeneity in the local mobility and a progressive increase in collective particle motion upon cooling that takes the form of string-like particle rearrangements. In a previous paper (Part I), we examined the possibility that fluctuations in potential energy E and particle mobility μ associated with this ‘dynamic heterogeneity’ might offer information about the scale of collective motion in glassy materials based on molecular dynamics simulations of the glassy interfacial region of Ni nanoparticles (NPs) at elevated temperatures. We found that the noise exponent associated with fluctuations in the Debye-Waller factor, a mobility related quantity, was directly proportional to the scale of collective motion L under a broad range of conditions, but the noise exponent associated with E(t) fluctuations was seemingly unrelated to L. In the present work, we focus on this unanticipated difference between potential energy and mobility fluctuations by examining these quantities at an atomic scale. We find that the string atoms exhibit a jump-like motion between two well-separated bands of energy states and the rate at which these jumps occur seems to be consistent with the phenomenology of the ‘slow-beta’ relaxation process of glass-forming liquids. Concurrently with these local E(t) jumps, we also find ‘quake-like’ particle displacements having a power-law distribution in magnitude so that particle displacement fluctuations within the strings are strikingly different from local E(t) fluctuations. An analysis of these E(t) fluctuations suggests that we are dealing with ‘discrete breather’ excitations in which large energy fluctuations develop in arrays of non-linear oscillators by virtue of large anharmonicity in the interparticle interactions and discreteness effects associated with particle packing. We quantify string collective motions on a fast caging

  14. Microscopic dynamics perspective on the relationship between Poisson's ratio and ductility of metallic glasses

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.; Wang, Li-Min; Liu, Riping; Wang, W. H.

    2014-01-01

    In metallic glasses a clear correlation had been established between plasticity or ductility with the Poisson's ratio νPoisson and alternatively the ratio of the elastic bulk modulus to the shear modulus, K/G. Such a correlation between these two macroscopic mechanical properties is intriguing and is challenging to explain from the dynamics on a microscopic level. A recent experimental study has found a connection of ductility to the secondary β-relaxation in metallic glasses. The strain rate and temperature dependencies of the ductile-brittle transition are similar to the reciprocal of the secondary β-relaxation time, τβ. Moreover, metallic glass is more ductile if the relaxation strength of the β-relaxation is larger and τβ is shorter. The findings indicate the β-relaxation is related to and instrumental for ductility. On the other hand, K/G or νPoisson is related to the effective Debye-Waller factor (i.e., the non-ergodicity parameter), f0, characterizing the dynamics of a structural unit inside a cage formed by other units, and manifested as the nearly constant loss shown in the frequency dependent susceptibility. We make the connection of f0 to the non-exponentiality parameter n in the Kohlrausch stretched exponential correlation function of the structural α-relaxation function, φ (t) = exp [ { - ( {t/{τ _α }})^{1 - n} }]. This connection follows from the fact that both f0 and n are determined by the inter-particle potential, and 1/f0 or (1 - f0) and n both increase with anharmonicity of the potential. A well tested result from the Coupling Model is used to show that τβ is completely determined by τα and n. From the string of relations, (i) K/G or νPoisson with 1/f0 or (1 - f0), (ii) 1/f0 or (1 - f0) with n, and (iii) τα and n with τβ, we arrive at the desired relation between K/G or νPoisson and τβ. On combining this relation with that between ductility and τβ, we have finally an explanation of the empirical correlation between

  15. Modeling correlated motion in filled skutterudites

    NASA Astrophysics Data System (ADS)

    Keiber, Trevor; Bridges, Frank

    2015-10-01

    Recent extended x-ray absorption fine structure (EXAFS) studies suggest that in skutterudites, the nearly square rings (such as As4 in CeFe4As12 ) are quite rigid and may vibrate with low-energy modes in one direction, similar to "rattler" atom vibrations. That work suggests that the motions of the square rings and the rattler atoms are coupled. In addition, for Ln Cu 3Ru4O12 , the second-neighbor pairs about L n have stiffer effective springs than the nearest-neighbor pairs. To investigate these systems, a one-dimensional, four-mass, linear chain spring model is developed to describe the recent experimental results and provide insight about the low-energy vibrations in such systems. Our model solves the resulting coupled network of overlapping weak and strong springs and determines the eigenfrequencies and eigenvectors. The dispersion curves show an acoustic mode, two different low-energy optical rattling modes involving both the rattler and square, and a noninteracting optical mode. Each rattler mode can couple to the acoustic mode, which generates avoided crossings characterized by flattening of the modes; this has important consequences for thermal transport. From these results we calculate atomic correlation functions and the Debye-Waller-like function used in EXAFS σ2 as a function of temperature. These calculations show that for the rattler-neighbor pairs, σ2 is a sum over several modes; it is not the result of a single mode. The inverse slope of σ2(T ) at high T provides a measure of the effective spring constants, and the results show that for small direct spring constants the effective spring constant can be significantly larger than the direct spring constants. The locations of the avoided crossings (between rattler modes and the acoustic mode) in q space can be tuned by the choice of both the rattler and the square atoms. Consequently, it may be possible to further reduce the thermal conductivity using a mixture of nanoparticles, each with avoided

  16. Scientific Advancements and Technological Developments of High P-T Neutron Diffraction at LANSCE, Los Alamos

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Daemen, L. L.; Zhang, J.

    2003-12-01

    In-situ high P-T neutron diffraction experiments provide unique opportunities to study the crystal structure, hydrogen bonding, magnetism, and thermal parameters of light elements (eg. H, Li, B) and heavy elements (eg. Ta, U, Pu,), that are virtually impossible to determine with x-ray diffraction techniques. For example, thermoelasticity and Debye-Waller factor as function of pressure and temperature can be derived using in-situ high P-T neutron diffraction techniques. These applications can also be extended to a much broader spectrum of scientific problems. For instance, puzzles in Earth science such as the carbon cycle and the role of hydrous minerals for water exchange between lithosphere and biosphere can be directly addressed. Moreover, by introducing in-situ shear, texture of metals and minerals accompanied with phase transitions at high P-T conditions can also be studied by high P-T neutron diffraction. We have successfully conducted high P-T neutron diffraction experiments at LANSCE and achieved simultaneous high pressures and temperatures of 10 GPa and 1500 K. With an average 3-6 hours of data collection, the diffraction data are of sufficiently high quality for the determination of structural parameters and thermal vibrations. We have studied hydrous mineral (MgOD), perovskite (K.15,Na.85)MgF3, clathrate hydrates (CH4-, CO2-, and H2-), metals (Mo, Al, Zr), and amorphous materials (carbon black, BMG). The aim of our research is to accurately map bond lengths, bond angles, neighboring atomic environments, and phase stability in P-T-X space. Studies based on high-pressure neutron diffraction are important for multi-disciplinary science and we welcome researchers from all fields to use this advanced technique. We have developed a 500-ton toroidal press, TAP-98, to conduct simultaneous high P-T neutron diffraction experiments inside of HIPPO (High-Pressure and Preferred-Orientation diffractometer). We have also developed a large gem-crystal anvil cell, ZAP-01

  17. Fast and anisotropic flexibility-rigidity index for protein flexibility and fluctuation analysis

    SciTech Connect

    Opron, Kristopher; Xia, Kelin; Wei, Guo-Wei

    2014-06-21

    Protein structural fluctuation, typically measured by Debye-Waller factors, or B-factors, is a manifestation of protein flexibility, which strongly correlates to protein function. The flexibility-rigidity index (FRI) is a newly proposed method for the construction of atomic rigidity functions required in the theory of continuum elasticity with atomic rigidity, which is a new multiscale formalism for describing excessively large biomolecular systems. The FRI method analyzes protein rigidity and flexibility and is capable of predicting protein B-factors without resorting to matrix diagonalization. A fundamental assumption used in the FRI is that protein structures are uniquely determined by various internal and external interactions, while the protein functions, such as stability and flexibility, are solely determined by the structure. As such, one can predict protein flexibility without resorting to the protein interaction Hamiltonian. Consequently, bypassing the matrix diagonalization, the original FRI has a computational complexity of O(N{sup 2}). This work introduces a fast FRI (fFRI) algorithm for the flexibility analysis of large macromolecules. The proposed fFRI further reduces the computational complexity to O(N). Additionally, we propose anisotropic FRI (aFRI) algorithms for the analysis of protein collective dynamics. The aFRI algorithms permit adaptive Hessian matrices, from a completely global 3N × 3N matrix to completely local 3 × 3 matrices. These 3 × 3 matrices, despite being calculated locally, also contain non-local correlation information. Eigenvectors obtained from the proposed aFRI algorithms are able to demonstrate collective motions. Moreover, we investigate the performance of FRI by employing four families of radial basis correlation functions. Both parameter optimized and parameter-free FRI methods are explored. Furthermore, we compare the accuracy and efficiency of FRI with some established approaches to flexibility analysis, namely

  18. Fast and anisotropic flexibility-rigidity index for protein flexibility and fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Opron, Kristopher; Xia, Kelin; Wei, Guo-Wei

    2014-06-01

    Protein structural fluctuation, typically measured by Debye-Waller factors, or B-factors, is a manifestation of protein flexibility, which strongly correlates to protein function. The flexibility-rigidity index (FRI) is a newly proposed method for the construction of atomic rigidity functions required in the theory of continuum elasticity with atomic rigidity, which is a new multiscale formalism for describing excessively large biomolecular systems. The FRI method analyzes protein rigidity and flexibility and is capable of predicting protein B-factors without resorting to matrix diagonalization. A fundamental assumption used in the FRI is that protein structures are uniquely determined by various internal and external interactions, while the protein functions, such as stability and flexibility, are solely determined by the structure. As such, one can predict protein flexibility without resorting to the protein interaction Hamiltonian. Consequently, bypassing the matrix diagonalization, the original FRI has a computational complexity of O(N^2). This work introduces a fast FRI (fFRI) algorithm for the flexibility analysis of large macromolecules. The proposed fFRI further reduces the computational complexity to O(N). Additionally, we propose anisotropic FRI (aFRI) algorithms for the analysis of protein collective dynamics. The aFRI algorithms permit adaptive Hessian matrices, from a completely global 3N × 3N matrix to completely local 3 × 3 matrices. These 3 × 3 matrices, despite being calculated locally, also contain non-local correlation information. Eigenvectors obtained from the proposed aFRI algorithms are able to demonstrate collective motions. Moreover, we investigate the performance of FRI by employing four families of radial basis correlation functions. Both parameter optimized and parameter-free FRI methods are explored. Furthermore, we compare the accuracy and efficiency of FRI with some established approaches to flexibility analysis, namely, normal

  19. Analysis of inelastic x-ray scattering spectra of low-temperature water

    PubMed

    Liao; Chen; Sette

    2000-02-01

    We analyze a set of high-resolution inelastic x-ray scattering (IXS) spectra from H2O measured at T=259, 273, and 294 K using two different phenomenological models. Model I, called the "dynamic cage model," combines the short time in-cage dynamics described by a generalized Enskog kinetic theory with a long-time cage relaxation dynamics described by an alpha relaxation. This model is appropriate for supercooled water where the cage effect is dominant and the existence of an alpha relaxation is evident from molecular-dynamics (MD) simulation data of extended simple point charge (SPC/E) model water. Model II is essentially a generalized hydrodynamic theory called the "three effective eigenmode theory" by de Schepper et al. 11. This model is appropriate for normal liquid water where the cage effect is less prominent and there is no evidence of the alpha relaxation from the MD data. We use the model I to analyze IXS data at T=259 K (supercooled water). We successfully extract the Debye-Waller factor, the cage relaxation time from the long-time dynamics, and the dispersion relation of high-frequency sound from the short time dynamics. We then use the model II to analyze IXS data at all three temperatures, from which we are able to extract the relaxation rate of the central mode and the damping of the sound mode as well as the dispersion relation for the high-frequency sound. It turns out that the dispersion relations extracted from the two models at their respective temperatures agree with each other giving the high-frequency sound speed of 2900+/-300 m/s. This is to be compared with a slightly higher value reported previously, 3200+/-320 m/s, by analyzing similar IXS data with a phenomenological-damped harmonic oscillator model 22. This latter model has traditionally been used exclusively for the analysis of inelastic scattering spectra of water. The k-dependent sound damping and central mode relaxation rate extracted from our model analyses are compared with the known

  20. Efficiency of preventive actions for landslides and flooding - evaluation of Scandinavian practices

    NASA Astrophysics Data System (ADS)

    Bergman, R.; Andersson-sköld, Y. B.; Nyberg, L.; Johansson, M.; Persson, E.

    2011-12-01

    Author: Ramona Bergman, Yvonne Andersson-Sköld, Lars Nyberg, Magnus Johansson, Erik Persson Preventive actions can be, and are frequently, taken to reduce accidents and their consequences in different ways. The MSB funded research programme "Effects of Society's Security actions" (ESS, 2009-2013) aims to study the relationship between such actions and their effects. The program is divided into three subgroups: Frequent accidents Natural hazards (such as flooding, erosion and landslide) Chemical and landfill accidents The results presented here covers natural hazards with focus on land slides and flooding. The results are based on Swedish/Scandinavian contexts. Natural events such as erosion, flooding and land slides are common, but the number of accidents (events causing severe negative impact) is rare. Therefore, in such analysis there is limited data and other information available which can be used for example in statistical analysis of actions and their effects. Instead, the analysis must be based on other information. Therefore, the analysis may have to include aspects that only can be assessed by scenario and "what-if" analyses. In this project the main method has been interviews with officials in Swedish municipalities and national agencies in Sweden and Norway. The two levels are chosen since policies are taken on national (or international) level, while the key actions and actors are on the municipal level. The interviews cover experiences and potential scenarios. In all municipalities, one politician and officials working with planning and rescue service have been interviewed. The study covers hazard and risk mapping, follow up of such maps, physical planning and lessons learned from previous events and activities. The final outcome of the research will be a review of what is found to be well functioning, identification of weak points and recommendations for the management of landslides, erosion and flooding. The present results indicate that hazard

  1. Globular clusters in the Magellanic Clouds - II. IR-array photometry for 12 globular clusters and contributions to the integrated cluster light

    NASA Astrophysics Data System (ADS)

    Ferraro, F. R.; Fusi Pecci, F.; Testa, V.; Greggio, L.; Corsi, C. E.; Buonanno, R.; Terndrup, D. M.; Zinnecker, H.

    1995-01-01

    drawn by Persson et al. and Frogel et al. that the J-K colour is mostly driven by the AGB stars, that V-K is substantially controlled by AGB and RGB stars (AGB stars being slightly more important), and that B-Vis partially influenced by the whole population of red stars brighter than the bulk of the RGB clump, but is also quite strongly dependent on the progressive fading and reddening of the turn-off stars due to age increase.

  2. Biosynthesis of adenovirus type 2 i-leader protein.

    PubMed Central

    Symington, J S; Lucher, L A; Brackmann, K H; Virtanen, A; Pettersson, U; Green, M

    1986-01-01

    The i-leader is a 440-base-pair sequence located between 21.8 and 23.0 map units on the adenovirus type 2 genome and is spliced between the second and third segments of the major tripartite leader in certain viral mRNA molecules. The i-leader contains an open translational reading frame for a hypothetical protein of Mr about 16,600, and a 16,000-Mr polypeptide (16K protein) has been translated in vitro on mRNA selected with DNA containing the i-leader (A. Virtanen, P. Aleström, H. Persson, M. G. Katze, and U. Pettersson, Nucleic Acids Res. 10:2539-2548, 1982). To determine whether the i-leader protein is synthesized during productive infection and to provide an immunological reagent to study the properties and functions of the i-leader protein, we prepared antipeptide antibodies directed to a 16-amino acid synthetic peptide which is encoded near the N terminus of the hypothetical i-leader protein and contains a high acidic amino acid and proline content. Antipeptide antibodies immunoprecipitated from extracts of adenovirus type 2-infected cells a major 16K protein that comigrated with a 16K protein translated in vitro. Partial N-terminal amino acid sequence analysis by Edman degradation of radiolabeled 16K antigen showed that methionine is present at residue 1 and leucine is present at residues 8 and 10, as predicted from the DNA sequence, establishing that the 16K protein precipitated by this antibody is indeed the i-leader protein. Thus, the i-leader protein is a prominent species that is synthesized during productive infection. The i-leader protein is often seen as a doublet on polyacrylamide gels, suggesting that either two related forms of i-leader protein are synthesized in infected cells or that a posttranslational modification occurs. Time course studies using immunoprecipitation analysis with antipeptide antibodies revealed that the E1A 289R T antigen and the E1B-19K (175R) T antigen are synthesized beginning at 2 to 3 and 4 to 5 h postinfection

  3. The Giant Branch of omega Centauri. IV. Abundance Patterns Based on Echelle Spectra of 40 Red Giants

    NASA Astrophysics Data System (ADS)

    Norris, John E.; Da Costa, G. S.

    1995-07-01

    Abundances of some 20 elements have been determined for a (biased) sample of 40 red giants having Mv < -1.5 in the chemically inhomogeneous globular cluster ω Centauri. The results are based on high-resolution, high signal-to-noise echelle spectra and permit one to examine the roles of primordial enrichment and stellar evolutionary mixing effects in the cluster. Our basic conclusions are as follows (1) There is an abundance range -1.8 < [Fe/H] < -0.8, and even more metal rich stars may exist in the cluster. (2) For the α (Mg, Si, Ca, Ti) and iron peak (Cr, Ni) elements and Sc and V, [metal/Fe] is flat as a function of [Fe/H] and is consistent with primordial enrichment from stars having mass greater than 10 Msun, as has been found for field halo stars. (3) There is a large scatter in the abundances of C, N, and 0. The bulk of the stars have -0.9 < [C/Fe] < -0.3 and [O/Fe] ˜ 0.3, as is found at the red giant branch tip in other "normal" (showing no spread in [Fe/H]) clusters of similar abundance, while there also exists a group of CN-strong stars having [C/Fe] ˜ -0.7 and [O/Fe] ˜ -0.5. Nitrogen appears to be enhanced in all of these carbon-depleted stars. These results are most readily explained in terms of evolutionary mixing effects not predicted by standard stellar evolution calculations and are consistent with the earlier suggestions of Cohen & Bell (1986) and Paltoglou & Norris (1989) concerning processing in both the CN and ON cycles in the stars being observed. In contrast, the group of CO-strong stars first identified by Persson et al. (1980) has [C/Fe] ˜ 0.0, [O/Fe] ˜ 0.4, and [N/Fe] ˜ 0.4 (or 0.9 if the nitrogen scale of Brown and Wallerstein is correct) and is suggestive of primordial enrichment of carbon and/or nitrogen from intermediate- and possibly low-mass stars, tempered by later stellar evolutionary effects. (4) [Na/Fe] and [Al/Fe] are anticorrelated with [O/Fe], and there is a positive correlation between [Na/Fe] and [Al/Fe], all of which

  4. Cosmic Blasts Much More Common, Astronomers Discover

    NASA Astrophysics Data System (ADS)

    2006-08-01

    produce gamma rays and X-rays have disks of material rotating rapidly about the central object," Soderberg said. The powerful gamma ray bursts tap the tremendous gravitational energy of their black hole to produce strong beams of energetic radiation, while less-energetic X-ray bursts like the Feburary event tap energy from the strong magnetic field of the magnetar, the scientists speculated. "This discovery means that the 'zoo' of cosmic explosions has just gotten more numerous and more diverse. It also means that our understanding of how the cores of massive stars collapse to produce this variety of explosions is less complete than we had thought," Frail added. Multiwavelength follow-up observations were required by the team to measure the total energy release of the explosion. In particular, Soderberg adds that "Radio observations with the Very Large Array were additionally required to determine the geometry of the ejecta. We find that unlike typical GRBs which produce pencil-beam jets, this object more resembles a spherical explosion." In addition to Soderberg and Frail, the research team includes Shri Kulkarni. Ehud Nakar, Edo Berger, Brian Cameron, Avishay Gal-Yam, Re'em Sari, Mansi Kasiwal, Eran Ofek, Arne Rau, Brad Cenko, Eric Persson and Dae-Sik Moon of Caltech, Derrick Fox and Dave Burrows of Pennsylvania State University, Roger Chevalier of the University of Virginia, Tsvi Piran of the Hebrew University, Paul Price of the University of Hawaii, Brian Schmidt of Mount Stromlo Observatory in Australia, Guy Pooley of the Mullard Radio Astronomy Observatory in the UK, Bryan Penprase of Pomona College, and Neil Gehrels of the NASA Goddard Space Flight Center. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. http://www.nrao.edu/

  5. Obituary: Einar A. Tandberg-Hanssen (1921-2011)

    NASA Astrophysics Data System (ADS)

    Gary, G.; Emslie, A.; Hathaway, David; Moore, Ronald

    2011-12-01

    Dr. Einar Andreas Tandberg-Hanssen was born on 6 August 1921, in Bergen, Norway, and died on July 22, 2011, in Huntsville, AL, USA, due to complications from ALS (Amyotrophic lateral sclerosis, often referred to as Lou Gehrig's disease). His parents were administrator Birger Tandberg-Hanssen (1883-1951) and secretary Antonie "Mona" Meier (1895-1967). He married Erna Rönning (27 October 1921 - 22 November 1994), a nurse, on 22 June 1951. She was the daughter of Captain Einar Rönning (1890-1969) and Borghild Lyshaug (1897-1980). Einar and Erna had two daughters, Else Biesman (and husband Allen of Rapid City, SD, USA) and Karin Brock (and husband Mike of Gulf Shores, AL, USA). At the time of his death Einar had eight grandchildren and eight great-grandchildren. Dr. Tandberg-Hanssen was an internationally-known member of the solar physics community, with over a hundred published scientific papers and several books, including Solar Activity (1967), Solar Prominences (1974), The Physics of Solar Flares (1988) and The Nature of Solar Prominences (1995). Einar grew up in Langesund and Skien, Norway, where he took the qualifying exams at Skien High School in 1941. After the war he studied natural sciences at the University of Oslo and received his undergraduate degree in astronomy in 1950. He worked as a research assistant in the Institute of Theoretical Astrophysics at the University of Oslo for three intervals in the 1950s, interspersed by fellowships at the Institut d'Astrophysique in Paris, Caltech in Pasadena, CA, the High Altitude Observatory in Boulder, CO, and the Cavendish Laboratory in the UK (at the invitation of British radio-astronomer Sir Martin Ryle). He earned a doctorate in astrophysics at the University in Oslo in 1960 with a dissertation titled "An Investigation of the Temperature Conditions in Prominences with a Special Study of the Excitation of Helium." From 1959-61, Tandberg-Hanssen was a professor at the University in Oslo. He then traveled back to

  6. NASA Announces 2009 Astronomy and Astrophysics Fellows

    NASA Astrophysics Data System (ADS)

    2009-02-01

    WASHINGTON -- NASA has selected fellows in three areas of astronomy and astrophysics for its Einstein, Hubble, and Sagan Fellowships. The recipients of this year's post-doctoral fellowships will conduct independent research at institutions around the country. "The new fellows are among the best and brightest young astronomers in the world," said Jon Morse, director of the Astrophysics Division in NASA's Science Mission Directorate in Washington. "They already have contributed significantly to studies of how the universe works, the origin of our cosmos and whether we are alone in the cosmos. The fellowships will serve as a springboard for scientific leadership in the years to come, and as an inspiration for the next generation of students and early career researchers." Each fellowship provides support to the awardees for three years. The fellows may pursue their research at any host university or research center of their choosing in the United States. The new fellows will begin their programs in the fall of 2009. "I cannot tell you how much I am looking forward to spending the next few years conducting research in the U.S., thanks to the fellowships," said Karin Oberg, a graduate student in Leiden, The Netherlands. Oberg will study the evolution of water and ices during star formation when she starts her fellowship at the Smithsonian Astrophysical Observatory in Cambridge, Mass. People Who Read This Also Read... Milky Way's Super-efficient Particle Accelerators Caught in The Act Cosmic Heavyweights in Free-for-all Galaxies Coming of Age in Cosmic Blobs Cassiopeia A Comes Alive Across Time and Space A diverse group of 32 young scientists will work on a wide variety of projects, such as understanding supernova hydrodynamics, radio transients, neutron stars, galaxy clusters and the intercluster medium, supermassive black holes, their mergers and the associated gravitational waves, dark energy, dark matter and the reionization process. Other research topics include

  7. Preface: SQM2006

    NASA Astrophysics Data System (ADS)

    Barish, Kenneth; Zhong Huang, Huan; Kapusta, Joseph; Odyniec, Grazyna; Rafelski, Johann; Whitten, Charles A., Jr.

    2006-12-01

    served as conference coordinator. She and her crew organized all the conference activities and she has been essential for the success of the conference. Staff members from UCLA, Vahe Ghazikhanian, Stephen Trentalange, Mauro Leonardo, Josephine Morrell, Friedel Adler, Tuyet-Hong Truong-Ung, Leticia Cabeza, Karin Nachtigal, Martin Simon, Dylan Thein, Lingyu Xu and Craig Reaves, and graduate students Jingguo Ma, Johan Gonzalez, Xiaoyan Lin, Priscilla Kurnadi and David Staszak, also provided essential support for the conference. We wish to thank Tony Chan, Dean of Physical Sciences at UCLA, Lawrence Berkeley National Laboratory, Brookhaven National Laboratory and the UCLA Department of Physics and Astronomy for financial support of the conference. Their sponsorship allowed many graduate students and junior physicists to attend the conference. We also thank the SQM2006 International Advisory Committee for their valuable input to the scientific programme and conference arrangement.

  8. The Hawaii trails project: comet-hunting in the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Hsieh, H. H.

    2009-10-01

    Context: The mysterious solar system object 133P/(7968) Elst-Pizarro is dynamically asteroidal, yet displays recurrent comet-like dust emission. Two scenarios were hypothesized to explain this unusual behavior: 1) 133P is a classical comet from the outer solar system that has evolved onto a main-belt orbit or 2) 133P is a dynamically ordinary main-belt asteroid on which subsurface ice has recently been exposed. If 1) is correct, the expected rarity of a dynamical transition onto an asteroidal orbit implies that 133P could be alone in the main belt. In contrast, if 2) is correct, other icy main-belt objects should exist and could also exhibit cometary activity. Aims: Believing 133P to be a dynamically ordinary, yet icy main-belt asteroid, I set out to test the primary prediction of the hypothesis: that 133P-like objects should be common and could be found by an appropriately designed observational survey. Methods: I conducted just such a survey - the Hawaii Trails Project - of selected main-belt asteroids in a search for objects displaying cometary activity. Optical observations were made of targets selected from among the Themis, Koronis, and Veritas asteroid families, the Karin asteroid cluster, and low-inclination, kilometer-scale outer-belt asteroids, using the Lulin 1.0 m, small and moderate aperture research telescope system (SMARTS) 1.0 m, University of Hawaii 2.2 m, southern astrophysical research (SOAR) 4.1 m, Gemini North 8.1 m, Subaru 8.2 m, and Keck I 10 m telescopes. Results: I made 657 observations of 599 asteroids, discovering one active object now known as 176P/LINEAR, leading to the identification of the new cometary class of main-belt comets (MBCs). These results suggest that there could be ~100 currently active MBCs among low-inclination, kilometer-scale outer-belt asteroids. Physically and statistically, MBC activity is consistent with initiation by meter-sized impactors. The estimated rate of impacts and sizes of resulting active sites, however

  9. Redetermination of the space weathering rate using spectra of Iannini asteroid family members

    NASA Astrophysics Data System (ADS)

    Willman, Mark; Jedicke, Robert; Nesvorný, David; Moskovitz, Nicholas; Ivezić, Željko; Fevig, Ronald

    2008-06-01

    We have obtained moderate S/N (˜85) spectra at a realized resolution of R˜100 for 11 members of the Iannini family, until recently the youngest known family at under 5 million years of age [Nesvorný, D., Bottke, W.F., Levison, H.F., Dones, L., 2003. Astrophys. J. 591, 486-497, 720-771]. The spectra were acquired using the Echellette Spectrograph and Imager in its low-resolution prism mode on the Keck II telescope. The family members belong to the S-complex of asteroids with perhaps some K class members. The Iannini family members' average spectral slope, defined as the slope of the best-fit line constrained to pivot about 1 at 550 nm, is (0.30±0.04)/μm, matching the (0.26±0.03)/μm reported by Jedicke et al. [Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M., 2004. Nature 429, 275-277] using SDSS [Ivezić, Ž., Jurić, M., Lupton, R.H., Tabachnik, S., Quinn, T., 2002. In: Tyson, J.A., Wolff, S. (Eds.), Survey and Other Telescope Technologies and Discoveries. In: Proc. SPIE, vol. 4836. SPIE, Bellingham, pp. 98-103] color photometry. Using our spectra for this family as well as new observations of Karin family members [Vernazza, P., Birlan, M., Rossi, A., Dotto, E., Nesvorný, D., Brunetto, R., Fornasier, S., Fulchignoni, M., Renner, S., 2006. Astron. Astrophys. 460, 945-951] and new classifications of some older families we have revised the space weathering rate of S-complex asteroids originally determined by Jedicke et al. [Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M., 2004. Nature 429, 275-277]. Following Jedicke et al. [Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M., 2004. Nature 429, 275-277] we parameterize the space weathering rate of the principal component color of the spectrum ( PC), which is correlated with the spectral slope, as PC(t)=PC(0)+ΔPC[1-exp]. Our revised rate suggests that the characteristic time scale for space weathering is τ=570±220 Myr and that new S-complex clusters

  10. Book Review: Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 15)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2002-12-01

    Pisa and the librarian Pozzetti at Bologna, and Karin Reich describes and edits Bessel's boo

  11. Raman Spectroscopy and Structure of MgSiO3 High Temperature C2/c Clinoenstatite

    NASA Astrophysics Data System (ADS)

    Kusu, R.; Yoshiasa, A.; Nishiyama, T.; Akihiko, N.; Maki, O.; Hiroshi, A.; Sugiyama, K.

    2014-12-01

    The high-temperature clinoenstatite (HT-CEn) is one of the important MgSiO3 pyroxene polymorph. The single-crystal of C2/c HT-CEn endmember is firstly synthesized by rapid pressure-temperature quenching from 15-16 GPa and 900-1900 °C [1]. No report that it is produced as single crystal or large domain had been made on the MgSiO3 endmember. The HT-CEn-type modifications were observed in Ca-poor Mg-Fe clinoenstatite and pigeonite and are always found to be unquenchable in rapid cooling. The high pressure and high temperature experiments of MgSiO3 composition were carried out with a Kawai-type multi-anvil apparatus. The samples were quenched by rapidly releasing the oil pressure load and/or by blow out of anvil cell gasket. The space group of C2/c is strictly determined by Rigaku RAPID Weissenberg photographs and synchrotron radiation. HT-CEn and HP-CEn have the greatly different beta angles of 109° and 101°, respectively. Raman spectra of HT-CEn and OEn single crystals were collected at ambient conditions. The unusual bonding distances frozen in the metastable structure. The observed average Mg1-O and Si-O distances in HT-CEn [1.997 and 1.620 Å, respectively] are shorter than those in HP-CEn at 7.9GPa. The average Mg2-O distance in HT-CEn [2.311 Å] is significantly longer than that in L-CEn, providing an abnormal larger distance for the Mg2 atom. The Mg2 polyhedron in HT-CEn is more irregular than that in HP-CEn. The Debye-Waller factor of atoms in HT-CEn have abnormally larger amplitude. The static irregularity of the atomic displacement caused by the transition is frozen in the metastable state. Almost all Raman peaks are broad owing to the large statistical positional arrangement of atoms in HT-CEn. The braod patterns have the common feature which were obserbed by the high temperature Raman spectroscopy for pyroxene. The peaks have been confirmed at 108, 259, 684, and 1097 cm-1. Peak positions for HT-CEn are different from those for protoenstatite under high

  12. The evolution and effectiveness of graduated licensing.

    PubMed

    Simpson, Herb M

    2003-01-01

    This paper traces the history of graduated licensing, starting about the point in time when Pat Waller's paper on the genesis of the concept ends, and examines the extent to which graduated licensing has produced reductions in collisions. It concludes with some general observations about future research needs, anticipating several of the papers that follow. The evolution of graduated licensing is chronicled, beginning with the early and largely unsuccessful efforts to introduce it in the United States in the late 1970s, through the pioneering efforts in New Zealand, which resulted in the first truly graduated system in 1987, to Canada where the program was introduced 7 years later, to the United States where it has flourished in more recent years. This 25-year history lesson hopefully creates an appreciation for the somewhat torturous journey that graduated licensing has experienced in achieving acceptance among the public and policy-makers-a journey that is not yet over, as subsequent papers in the symposium will show. The proliferation of graduated licensing in recent years is a mixed blessing-the wider adoption of graduated licensing has been a very positive development, but the programs that have evolved are anything but homogeneous in structure or content. Although this is often necessary for various reasons, it is worrisome that some programs are graduated licensing in name only. This suggests that future efforts to promote graduated licensing must emphasize adherence to the fundamental risk reduction and multistage principles on which the concept is based. The paper also considers the extent to which graduated licensing achieves its objective of reducing collisions among those covered by the program. Understandably, most jurisdictions would not introduce graduated licensing until it was shown to be effective and this, to some extent, slowed the process of implementation. The obvious irony is that it could not be shown to be effective until it was introduced

  13. Experimental Compressibility of Molten Hedenbergite at High Pressure

    NASA Astrophysics Data System (ADS)

    Agee, C. B.; Barnett, R. G.; Guo, X.; Lange, R. A.; Waller, C.; Asimow, P. D.

    2010-12-01

    Experiments using the sink/float method have bracketed the density of molten hedenbergite (CaFeSi2O6) at high pressures and temperatures. The experiments are the first of their kind to determine the compressibility of molten hedenbergite at high pressure and are part of a collaborative effort to establish a new database for an array of silicate melt compositions, which will contribute to the development of an empirically based predictive model that will allow calculation of silicate liquid density and compressibility over a wide range of P-T-X conditions where melting could occur in the Earth. Each melt composition will be measured using: (i) double-bob Archimedean method for melt density and thermal expansion at ambient pressure, (ii) sound speed measurements on liquids to constrain melt compressibility at ambient pressure, (iii) sink/float technique to measure melt density to 15 GPa, and (iv) shock wave measurements of P-V-E equation of state and temperature between 10 and 150 GPa. Companion abstracts on molten fayalite (Waller et al., 2010) and liquid mixes of hedenbergite-diopside and anorthite-hedenbergite-diopside (Guo and Lange, 2010) are also presented at this meeting. In the present study, the hedenbergite starting material was synthesized at the Experimental Petrology Lab, University of Michigan, where melt density, thermal expansion, and sound speed measurements were also carried out. The starting material has also been loaded into targets at the Caltech Shockwave Lab, and experiments there are currently underway. We report here preliminary results from static compression measurement performed at the Department of Petrology, Vrije Universiteit, Amsterdam, and the High Pressure Lab, Institute of Meteoritics, University of New Mexico. Experiments were carried out in Quick Press piston-cylinder devices and a Walker-style multi-anvil device. Sink/float marker spheres implemented were gem quality synthetic forsterite (Fo100), San Carlos olivine (Fo90), and

  14. EDITORIAL: Wind energy

    NASA Astrophysics Data System (ADS)

    Mann, Jakob; Nørkær Sørensen, Jens; Morthorst, Poul-Erik

    2008-01-01

    addressed within the issue is how much conventional power production can be replaced by the ceaseless wind, with the question of how Greece's target of 29% renewables by 2020 is to be met efficiently. Other topics include an innovative way to determine the power curve of a turbine experimentally more accurately, the use of fluid dynamics tools to investigate the implications of placing vortex generators on wind turbine blades (thereby possibly improving their efficiency) and a study of the perception of wind turbine noise. It turns out that a small but significant fraction of wind turbine neighbours feel that turbine generated noise impairs their ability to rest. The annoyance is correlated with a negative attitude towards the visual impact on the landscape, but what is cause and effect is too early to say. As mentioned there is a rush for wind turbines in many countries. However, this positive development for the global climate is currently limited by practical barriers. One bottleneck is the difficulties for the sub-suppliers of gears and other parts to meet the demand. Another is the difficulties to meet the demand for engineers specialized in wind. For that reason the Technical University of Denmark (DTU) recently launched the world's first Wind Energy Masters Program. Here and elsewhere in the world of wind education and research we should really speed up now, as our chances of contributing to emission free energy production and a healthier global climate have never been better. Focus on Wind Energy Contents The articles below represent the first accepted contributions and further additions will appear in the near future. Wind turbines—low level noise sources interfering with restoration? Eja Pedersen and Kerstin Persson Waye On the effect of spatial dispersion of wind power plants on the wind energy capacity credit in Greece George Caralis, Yiannis Perivolaris, Konstantinos Rados and Arthouros Zervos Large-eddy simulation of spectral coherence in a wind turbine wake

  15. Pollen-inferred quantitative reconstructions of Holocene land-cover in NW Europe for the evaluation of past climate-vegetation feedbacks - The Swedish LANDCLIM project and the NordForsk LANDCLIM network

    NASA Astrophysics Data System (ADS)

    Gaillard, Marie-Jose; Sugita, Shinya; Rundgren, Mats; Smith, Benjamin; Mazier, Florence; Trondman, Anna-Kari; Fyfe, Ralph; Kokfelt, Ulla; Nielsen, Anne-Birgitte; Strandberg, Gustav

    2010-05-01

    of ca. 1o x 1o. The REVEALS estimates of the past cover of PFTs will be 1) compared with the outputs of the LPJ-GUESS (10 PFTs), a widely-used dynamic vegetation model and 2) used as an alternative to the LPJ-GUESS-simulated vegetation (3 PFTs) to run for the past the regional climate model RCA3 developed at the Rossby Centre, Norrköping, Sweden. The study will evaluate and further refine these models (RCA3 and LPJ-GUESS) using a data-model comparison approach that incorporates new syntheses of palaeoclimatic data as well. It will lead to new assessments of the possible effect of various factors on climate, such as deforestations and afforestations, and changes in vegetation composition and spatial patterns of land cover/land use. Refined climate models and empirical land-cover reconstructions will shed new light on controversial hypotheses of past climate change and human impacts, such as the "Ruddiman hypothesis". First maps of REVEALS estimates of plant functional types (PFTs) are now available for Sweden, Norway, Finland, Denmark, Estonia, Poland, Germany, The Czech Republic, Switzerland and Britain (see Mazier et al. C1.21 and Trondman et al. C1.22). Correlation tests show that the REVEALS estimates are robust in terms of ranking of the PFTs' abundance (see Mazier et al, C1.21). The LANDCLIM project and network are a contribution to the IGBP-PAGES-Focus 4 PHAROS programme on human impact on environmental changes in the past. The following LANDCLIM members are acknowledged for providing pollen records, for help with pollen databases, and for providing results to the project: Mihkel Kangur and Tiiu Koff (Univ. Tallinn, Tallinn); Erik Kjellström (SMHI, Norrköping), Anna Broström, Lena Barnekow and Thomas Persson (GeoBiosphere Science Centre, Lund University); Anneli Poska (Physical Geography and Ecosystems Analysis, Lund University); Thomas Giesecke (Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen), Anne Bjune and John Birks (Dept. of

  16. EDITORIAL: Wind energy

    NASA Astrophysics Data System (ADS)

    Mann, Jakob; Nørkær Sørensen, Jens; Morthorst, Poul-Erik

    2008-01-01

    addressed within the issue is how much conventional power production can be replaced by the ceaseless wind, with the question of how Greece's target of 29% renewables by 2020 is to be met efficiently. Other topics include an innovative way to determine the power curve of a turbine experimentally more accurately, the use of fluid dynamics tools to investigate the implications of placing vortex generators on wind turbine blades (thereby possibly improving their efficiency) and a study of the perception of wind turbine noise. It turns out that a small but significant fraction of wind turbine neighbours feel that turbine generated noise impairs their ability to rest. The annoyance is correlated with a negative attitude towards the visual impact on the landscape, but what is cause and effect is too early to say. As mentioned there is a rush for wind turbines in many countries. However, this positive development for the global climate is currently limited by practical barriers. One bottleneck is the difficulties for the sub-suppliers of gears and other parts to meet the demand. Another is the difficulties to meet the demand for engineers specialized in wind. For that reason the Technical University of Denmark (DTU) recently launched the world's first Wind Energy Masters Program. Here and elsewhere in the world of wind education and research we should really speed up now, as our chances of contributing to emission free energy production and a healthier global climate have never been better. Focus on Wind Energy Contents The articles below represent the first accepted contributions and further additions will appear in the near future. Wind turbines—low level noise sources interfering with restoration? Eja Pedersen and Kerstin Persson Waye On the effect of spatial dispersion of wind power plants on the wind energy capacity credit in Greece George Caralis, Yiannis Perivolaris, Konstantinos Rados and Arthouros Zervos Large-eddy simulation of spectral coherence in a wind turbine wake

  17. Cosmic Blasts Much More Common, Astronomers Discover

    NASA Astrophysics Data System (ADS)

    2006-08-01

    explosions is that the blasts that produce gamma rays and X-rays have disks of material rotating rapidly about the central object," Soderberg said. The powerful gamma ray bursts tap the tremendous gravitational energy of their black hole to produce strong beams of energetic radiation, while less-energetic X-ray bursts like the Feburary event tap energy from the strong magnetic field of the magnetar, the scientists speculated. "This discovery means that the 'zoo' of cosmic explosions has just gotten more numerous and more diverse. It also means that our understanding of how the cores of massive stars collapse to produce this variety of explosions is less complete than we had thought," Frail added. Multiwavelength follow-up observations were required by the team to measure the total energy release of the explosion. In particular, Soderberg adds that "Radio observations with the Very Large Array were additionally required to determine the geometry of the ejecta. We find that unlike typical GRBs which produce pencil-beam jets, this object more resembles a spherical explosion." In addition to Soderberg and Frail, the research team includes Shri Kulkarni. Ehud Nakar, Edo Berger, Brian Cameron, Avishay Gal-Yam, Re'em Sari, Mansi Kasiwal, Eran Ofek, Arne Rau, Brad Cenko, Eric Persson and Dae-Sik Moon of Caltech, Derrick Fox and Dave Burrows of Pennsylvania State University, Roger Chevalier of the University of Virginia, Tsvi Piran of the Hebrew University, Paul Price of the University of Hawaii, Brian Schmidt of Mount Stromlo Observatory in Australia, Guy Pooley of the Mullard Radio Astronomy Observatory in the UK, Bryan Penprase of Pomona College, and Neil Gehrels of the NASA Goddard Space Flight Center. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  18. Human-induced environmental degradation during Anthropocene in Turkey

    NASA Astrophysics Data System (ADS)

    Efe, Recep; Curebal, Isa; Soykan, Abdullah; Sönmez, Suleyman

    2015-04-01

    .; Andreae, M.O.; Kadereit, J.W.; Esper, J.; Scholz, D.; Pöschl, U.; Jacob, D.E.; Schöne, B.R.; Schreg, R.; Vött, A.; Jordan, D.; Lelievld, J.: Weller, C.G.; Alt, K.W.; Gaudzinski-Windheuser, S.; Bruhn, K.C.; Tost, H.; Sirocko, F.; Crutzen, P.J. (2013), The Paleoanthropocene - The beginnings of anthropogenic environmental change, Anthropocene, 3: 83-88. Hoang, H.T.T.; Vanacker, V.; Van Rompaey, A.; Vu, K.C.; Nguyen, A.T. (2014), Changing human-landscape interactions after development of tourism in the nothern Vietnamese Highlands, Anthropocene, 5: 42-51 Matteo, G.; Lingua, E.; Marzano, R.; Urbinati, C.; Bhuju, D.; Carrer, M. (2014), Human interactions with forest landscape in the Khumbu valley, Nepal, Anthropocene, 6: 39-47 Sanderson, E.W.; Jaiteh, M.; Levy, M.A.; Redford, K.H.; Wannebo, A.V.; Woolmer, G. (2002), The Human Footprint and the Last of the Wild. Bioscience 52: (10).891-904 Steffen, W.; Persson, A.; Deutsch, L.; Zalasiewicz, J.; Williams, M.; Richardson, K.; Crumley, C.; Crutzen, P.; Folke, C.; Gordon, L.; Molina, M.; Ramanathan, V., Rockström, J.; Scheffer, M.; Schellnhuber, H.J.; Svedin, U. (2011), The Anthropocene: From Global Change to Planetary Stewardship, AMBIO, 40: 739-761 Web-1 http://www.anthropocene.info/en/home Zalasiewicz, J.; Williams, M.; Smith, A.; L. Barry, T.; L. Coe, A.; R. Bown, P.; Brenchley, P.; Cantrill, D.; Gale, A.; Gibbard, P.; Gregory, F.J.; Hounslow, M.W.; Kerr, A.C.; Pearson, P.; Knox, R.; Powell, J.; Waters, C.; Marshall, J.; Oates, M.; Rawson, P.; Stone, P. (2008), Are we now living in the Anthropocene? GSA Today 18 (2): 4-8.

  19. Unravelling the Mystery of Massive Star Birth - All Stars are Born the Same Way

    NASA Astrophysics Data System (ADS)

    2010-07-01

    of a screw on the International Space Station, or more than ten times the resolution possible with current visible-light telescopes in space. With this unique capability, complemented by observations done with another of ESO's telescopes, the 3.58-metre New Technology Telescope at La Silla, Kraus and colleagues were able to detect a disc around IRAS 13481-6124. "This is the first time we could image the inner regions of the disc around a massive young star", says Kraus. "Our observations show that formation works the same for all stars, regardless of mass." The astronomers conclude that the system is about 60 000 years old, and that the star has reached its final mass. Because of the intense light of the star - 30 000 times more luminous than our Sun - the disc will soon start to evaporate. The flared disc extends to about 130 times the Earth-Sun distance - or 130 astronomical units (AU) - and has a mass similar to that of the star, roughly twenty times the Sun. In addition, the inner parts of the disc are shown to be devoid of dust. "Further observations with the Atacama Large Millimeter/submillimeter Array (ALMA), currently being constructed in Chile, could provide much information on these inner parts, and allow us to better understand how baby massive stars became heavy," concludes Kraus. More information This research was presented in a paper to appear in this week issue of Nature ("A hot compact dust disk around a massive young stellar object", by S. Kraus et al.). The team is composed of Stefan Kraus (University of Michigan, USA), Karl-Heinz Hofmann, Karl M. Menten, Dieter Schertl, Gerd Weigelt, Friedrich Wyrowski, and Anthony Meilland (Max-Planck-Institut für Radioastronomie, Bonn, Germany),Karine Perraut (Laboratoire d'Astrophysique de Grenoble, France), Romain Petrov and Sylvie Robbe-Dubois (Université de Nice Sophia-Antipolis/CNRS/Observatoire de la Côte d'Azur, France), Peter Schilke (Universität zu Köln, Germany), and Leonardo Testi (ESO).

  20. Obituary: Einar A. Tandberg-Hanssen (1921-2011)

    NASA Astrophysics Data System (ADS)

    Gary, G.; Emslie, A.; Hathaway, David; Moore, Ronald

    2011-12-01

    Dr. Einar Andreas Tandberg-Hanssen was born on 6 August 1921, in Bergen, Norway, and died on July 22, 2011, in Huntsville, AL, USA, due to complications from ALS (Amyotrophic lateral sclerosis, often referred to as Lou Gehrig's disease). His parents were administrator Birger Tandberg-Hanssen (1883-1951) and secretary Antonie "Mona" Meier (1895-1967). He married Erna Rönning (27 October 1921 - 22 November 1994), a nurse, on 22 June 1951. She was the daughter of Captain Einar Rönning (1890-1969) and Borghild Lyshaug (1897-1980). Einar and Erna had two daughters, Else Biesman (and husband Allen of Rapid City, SD, USA) and Karin Brock (and husband Mike of Gulf Shores, AL, USA). At the time of his death Einar had eight grandchildren and eight great-grandchildren. Dr. Tandberg-Hanssen was an internationally-known member of the solar physics community, with over a hundred published scientific papers and several books, including Solar Activity (1967), Solar Prominences (1974), The Physics of Solar Flares (1988) and The Nature of Solar Prominences (1995). Einar grew up in Langesund and Skien, Norway, where he took the qualifying exams at Skien High School in 1941. After the war he studied natural sciences at the University of Oslo and received his undergraduate degree in astronomy in 1950. He worked as a research assistant in the Institute of Theoretical Astrophysics at the University of Oslo for three intervals in the 1950s, interspersed by fellowships at the Institut d'Astrophysique in Paris, Caltech in Pasadena, CA, the High Altitude Observatory in Boulder, CO, and the Cavendish Laboratory in the UK (at the invitation of British radio-astronomer Sir Martin Ryle). He earned a doctorate in astrophysics at the University in Oslo in 1960 with a dissertation titled "An Investigation of the Temperature Conditions in Prominences with a Special Study of the Excitation of Helium." From 1959-61, Tandberg-Hanssen was a professor at the University in Oslo. He then traveled back to

  1. VLBA Changes Picture of Famous Star-Forming Region

    NASA Astrophysics Data System (ADS)

    2007-10-01

    Using the supersharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA), astronomers have made the most precise measurement ever of the distance to a famous star-forming region. The measurement -- to the heavily studied Orion Nebula -- changes scientists' understanding of the characteristics of the young stars in the region. Parallax Diagram Trigonometric Parallax method determines distance to star by measuring its slight shift in apparent position as seen from opposite ends of Earth's orbit. CREDIT: Bill Saxton, NRAO/AUI/NSF Star Track Apparent track of star GMR A in the Orion Nebula Cluster, showing shift caused by Earth's orbital motion and star's movement in space. CREDIT: Sandstrom et al., NRAO/AUI/NSF Click on Images for Larger Files "This measurement is four times more precise than previous distance estimates. Because our measurement reduces the distance to this region, it tells us that the stars there are less bright than thought before, and changes the estimates of their ages," said Geoff Bower, an astronomer at the University of California at Berkeley. Bower, along with Karin Sandstrom, J.E.G. Peek, Alberto Bolatto and Richard Plambeck, all of Berkeley, published their findings in the October 10 edition of the Astrophysical Journal. The scientists determined the distance to a star called GMR A, one of a cluster of stars in the Orion Nebula, by measuring the slight shift in the star's apparent position in the sky caused by the Earth's motion around the Sun. Observing the star when the Earth is on opposite sides of its annual orbit allows astronomers to measure the angle of this small shift and thus provides a direct trigonometric calculation of its distance. "By using this technique, called parallax, we get a direct measurement that does not depend on various assumptions that are required to use less-direct methods," Bower said. "Only a telescope with the remarkable ability to see fine detail that is provided by the VLBA is

  2. Understanding Electrocatalytic Pathways in Low and Medium Temperature Fuel Cells: Synchrotron-based In Situ X-Ray Absorption Spectroscopy

    SciTech Connect

    Mukerjee, S.; Ziegelbauer, J; Arruda, T; Ramaker, D; Shyam, B

    2008-01-01

    transmission beams respectively. When the energy of the incident X-rays exceed the electron binding energy (E{sub 0}) of the element under investigation, the electron is ejected from the core to available excited states in the form of a photoelectron with kinetic energy: E{sub k} = h? - E{sub 0} (2) with, E{sub k} being the kinetic energy of the released photoelectron and h? the energy of the incident beam. In general, the X-ray absorption spectrum is broken down into two distinct energy regions: the X-ray absorption near-edge structure or XANES (-50eV {le} E{sub 0} {le} 50eV) and the extended X-ray absorption fine-structure or EXAFS (50eV {le} E{sub 0} {le} {approx}1000eV). The XANES region is dominated by low-energy photoelectrons which undergo multiple scattering events. As such, it can reveal information about oxidation state, local symmetry, electronic structure, and the extent of oxidation of a material. Due to this complex multiple scattering, there is no simple XANES equation to describe it quantitatively. However, recent advancements in computers and the evolution of numerical methods such as the FEFF code have made possible reliable XANES simulations. Photoelectrons in the EXAFS region have high enough E{sub k} to undergo primarily single back-scattering events. These back-scattered photoelectrons interfere with the outgoing photoelectrons, causing the oscillations in the absorption spectrum. Using the previously developed EXAFS equations it is now possible to model EXAFS data to determine coordination numbers, bond distances, and mean-square disorder (commonly referred to as Debye-Waller factor). EXAFS data is often shown by Fourier Transforming KSpace into distance, r, space where the total magnitude is plotted against the radial coordinates. This allow for easy qualitative comparison of samples. Employing EXAFS on nanoscale materials has the added advantage that it can quantitatively illustrate changes in atom-atom coordination, which can be related to particle

  3. Water-level altitudes 2010 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2009 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    USGS Publications Warehouse

    Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

    2010-01-01

    -foot rise (2009-10), from a 25-foot decline to a 35-foot rise (2005-10), from a 40-foot decline to an 80-foot rise (1990-2010), and from a 140-foot decline to a 200-foot rise (1977-2010). In 2010, water-level-altitude contours for the Evangeline aquifer ranged from 300 feet below datum in north-central Harris County to 200 feet above datum at the boundary of Waller, Montgomery, and Grimes Counties. Water-level-altitude changes in the Evangeline aquifer ranged from a 58-foot decline to a 69-foot rise (2009-10), from an 80-foot decline to an 80-foot rise (2005-10), from a 200-foot decline to a 220-foot rise (1990-2010), and from a 320-foot decline to a 220-foot rise (1977-2010). In 2010, water-level-altitude contours for the Jasper aquifer ranged from 200 feet below datum in south-central Montgomery County to 250 feet above datum in eastern-central Grimes County. Water-level-altitude changes in the Jasper aquifer ranged from a 39-foot decline to a 39-foot rise (2009-10), from a 110-foot decline to no change (2005-10), and from a 180-foot decline to no change (2000-10). Compaction of subsurface materials (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973, or later, and ending in December 2009, cumulative clay compaction data measured by 12 extensometers ranged from 0.088 foot at the Texas City-Moses Lake site to 3.559 foot at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface materials. Therefore, it is not possible to extrapolate or infer a rate of clay compaction for an area based on the rate of compaction measured at a nearby extensometer.

  4. Water-level altitudes 2011 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2010 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    USGS Publications Warehouse

    Johnson, Michaela R.; Ramage, Jason K.; Kasmarek, Mark C.

    2011-01-01

    decline to an 80-foot rise (2006–11), from a 140-foot decline to a 100-foot rise (1990–2011), and from a 120-foot decline to a 200-foot rise (1977–2011). In 2011, water-level-altitude contours for the Evangeline aquifer ranged from 300 feet below datum in north-central Harris County to 200 feet above datum at the boundary of Waller, Montgomery, and Grimes Counties. Water-level-altitude changes in the Evangeline aquifer ranged from a 43-foot decline to a 73-foot rise (2010–11), from a 40-foot decline to a 160-foot rise (2006–11), from a 200-foot decline to a 240-foot rise (1990–2011), and from a 340-foot decline to a 260-foot rise (1977–2011). In 2011, water-level-altitude contours for the Jasper aquifer ranged from 200 feet below datum in south-central Montgomery County to 250 feet above datum in east-central Grimes County. Water-level-altitude changes in the Jasper aquifer ranged from a 45-foot decline to a 29-foot rise (2010–11), from a 90-foot decline to a 10-foot rise (2006–11), and from a 190-foot decline to no change (2000–11). Compaction of subsurface materials (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973, or later, and ending in December 2010, cumulative clay compaction data measured by 12 extensometers ranged from 0.100 foot at the Texas City–Moses Lake site to 3.544 foot at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface materials. Therefore, it is not possible to extrapolate or infer a rate of clay compaction for an area based on the rate of compaction measured at a nearby extensometer.

  5. Book Review: Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 15)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2002-12-01

    Pisa and the librarian Pozzetti at Bologna, and Karin Reich describes and edits Bessel's book critique of Gauss' Theoria Motus. How many one-time astronomers have to earn their living in other ways, become distracted from astronomical research, and vanish from the horizon of astronomical history? In the ninth paper, Hans-Joachim Ilgauds has traced the life of Georg Koch (1851-1905), who started his career as an astronomer at Leipzig Observatory in 1874. Later Koch worked at Hamburg Observatory, and then became an employee at the statistical office in Kiel, and finally director of the statistical office of the Hamburg revenue service. He was a collaborator for the statistical yearbook of German cities, and also contributed to a book investigating the causes and the impact of the cholera epidemic of 1892 in Hamburg. The last two papers deal with the circumstances of the discovery of the first Near-Earth asteroid (433) Eros. It was recorded on photographic plates taken at the Urania-Sternwarte Berlin and at Nice Observatory. The Berlin observer Witt announced the discovery, and only later, the Nice observer Charlois published a position of Eros. While all plates have disappeared, the authors Hans Scholl and Lutz D. Schmadel could prove that the Nice plate was poorly guided and Charlois would have been unable to discover the object. From a copy of the Berlin plate, published 50 years after the discovery by Witt's co-observer F. Linke, the exact position was determined, and the time of observation (which had not been published) was derived. The second article, by Lutz D. Schmadel, deals with the life of the Eros co-discoverer Felix Linke (1879-1959), who later worked in statistic offices, was a frequent writer of popular scientific articles, and later the editor of a journal, "Technik im Hotel'', and author of a book of the same title. As can be seen from the summaries given above, this collection of essays deals mainly with historical events that occurred in Germany and

  6. a Passage to the Universe

    NASA Astrophysics Data System (ADS)

    1995-11-01

    a concluding Press Conference , during which the outcome of this unique event will be summarized by the participants and the organisers: Monday, November 20, 1995, 15:30 pm, at the ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany List of National First-Prize Winners Belgium: Mr. Freddy Allemeersch (Teacher), Mr. Pieter De Ceuninck, Mr. Jeroen Staelens (Onze-Lieve-Vrouwecollege, Brugge) Denmark: Mr. Joern C. Olsen, Mr. Henrik Struckmann, Mr. Uffe A. Hansen, Mr. Mogens Winther (Teacher) (Soenderborg Amtsgymnasium) Finland: Mr. Reima Eresmaa, Ms. Laura Elina Nykyri, Ms. Reetamaija Janhonen (Cygnaeues-Lukeo, Jyvaeskylae and Jyvaeskylaen Lyseon Lukeo) France: Mr. Rene Cavaroz (Teacher), Mr. Vincent Hardy, Mr. Antoine Lesuffleur (Lycee Chartier, Bayeux) Germany: Ms. Dorothee Barth, Mr. Walter Czech (Teacher), Mr. Uwe Kranz, Ms. Karin Wieland (Immanuel-Kant-Gymnasium, Leinfelden-Echterdingen, Baden-Wuerttemberg) Greece: Ms. Agni Ioannidi, Ms. Elena Katifori, Mr. Vassilis Samiotis, Mr. Vassillos Tzotzes (Teacher) (Second Varvakelo Experimental Lyceum, Athens) Ireland: Mr. Declan Maccuarta (Teacher), Mr. Colm Mcloughlin (St. Peter's College, Wexford, Co. Wexford) Italy: Mr. Pasquale Ciarletta, Ms. Francesca D'elia, Ms. Ada Fortugna (Teacher), Mr. Alfredo Pudano (Liceo Scientifico `Leonardo da Vinci', Reggio Calabria) The Netherlands: Mr. Alex De Beer, Mr. Klaas Huijbregts, Mr. Ruud Nellen (Norbertuscollege, Rosendaal) Spain: Mr. Aritz Atela Aio, Mr. Julen Sarasola Manich (Teacher), Mr. Jon Huertas Rodriquez (Txorierri Batxilergoko Institua, Derio Bizkaia) Sweden: Mr. Rahman Amanullah, Mr. Kjell L. Bonander (Teacher), Mr. Tomas Oppelstrup, Ms. Christin Wiedemann (Saltsjoebadens Samskola, Saltsjoebaden) United Kingdom: Mr. Michael Ching, Dr. Richard Field (Teacher) (Oundle School, Peterborough) National Committees Further information about the national contests may be obtained from the National Committees: Belgium: Dr. C. Sterken, Vrije Universiteit

  7. ESA's Integral detects closest cosmic gamma-ray burst

    NASA Astrophysics Data System (ADS)

    2004-08-01

    be just sensitive enough to reveal a few more of them in the years to come. These could be just the tip of the iceberg and future gamma-ray observatories, such as the planned NASA's Swift mission, should be able to extend this search to a much larger volume of the Universe and find many more sub-energetic GRBs. Notes for editors The results of this investigation are presented in two articles that have appeared in today's issue of the scientific journal Nature. One of them, by S. Sazonov, A. Lutovinov and R. Sunyaev, is entitled "An apparently normal gamma-ray burst with unusually low luminosity". The other, entitled "The sub-energetic GRB 031203 as a cosmic analogue to GRB 980425", is signed by A. Soderberg, S. Kulkarni, E. Berger, D. Fox, M. Sako, D. Frail, A. Gal-Yam, D. Moon, S. Cenko, S. Yost, M. Phillips, E. Persson, W. Freedman, P. Wyatt, R. Jayawardhana and D. Paulson. The original announcement of the Integral detection of GRB 031203 was made by D. Goetz, S. Mereghetti, M. Beck, J. Borkowski and N. Mowlavi, via the Circular Service of the GRB Co-ordinates Network. More about Integral The International Gamma Ray Astrophysics Laboratory (Integral) is the first space observatory that can simultaneously observe celestial objects in gamma rays, X-rays and visible light. Integral was launched on a Russian Proton rocket on 17 October 2002 into a highly elliptical orbit around Earth. Its principal targets include regions of the galaxy where chemical elements are being produced and compact objects, such as black holes. For more information about Integral please see: http://www.esa.int/esaSC/spk.html More about XMM-Newton ESA's XMM-Newton can detect more X-ray sources than any previous satellite and is helping to solve many cosmic mysteries of the violent Universe, from black holes to the formation of galaxies. It was launched on 10 December 1999, using an Ariane-5 rocket, from French Guiana. It is expected to return data for a decade. XMM-Newton's high-tech design uses

  8. Congratulations to Carey King

    NASA Astrophysics Data System (ADS)

    Hall, Charles A. S.

    2012-03-01

    importance of these more comprehensive EROIs but we do understand that our usual methods of including only energy used directly (e.g. to run a pump) or indirectly (e.g. to manufacture the steel forms used) greatly underestimates the total amount of energy needed to produce energy. In conclusion, Carey King appears to be one of the real rising energy stars as energy becomes again much more important. He is very bright, original and is a very hard worker. I look forward to much exciting, innovative and important work from his endeavors. References Barnett H and Morse C 1963 Scarcity and Growth: The Economics of Natural Resource Availability (Baltimore, MD: Johns Hopkins Press) Cleveland C J, Costanza R, Hall C A S and Kaufmann R 1984 Energy and the United States economy: a biophysical perspective Science 225 890-7 Denison E F 1989 Estimates of Productivity Change by Industry, an Evaluation and an Alternative (Washington, DC: The Brookings Institution) Hall C A S 1972 Migration and metabolism in a temperate stream ecosystem Ecology 53 585-604 Hall C A S and Cleveland C J 1981 Petroleum drilling and production in the United States: yield per effort and net energy analysis Science 211 576-9 Hall C A S and Klitgaard K 2011 Energy and the Wealth of Nations: Understanding the Biophysical Economy (New York: Springer) Kaufmann R 2004 The mechanisms for autonomous energy efficiency increases: a cointegration analysis of the US Energy/GDP Ratio The Energy Journal 25 63-86 King C W 2010 Energy intensity ratios as net energy measures of United States energy production and expenditures Environ. Res. Lett. 5 044006 Murphy D J and Hall C A S 2011 Energy return on investment, peak oil, and the end of economic growth in 'Ecological Economics Reviews' ed Robert Costanza, Karin Limburg and Ida Kubiszewski Ann. N.Y. Acad. Sci. 1219 52-72 Solow R M 1974 The economics of resources or the resources of economics American Economic Review 66 1-14 Odum H T 1973 Environment, Power and Society (New York

  9. Biological N2-FIXATION and Mineral N-Fertilization Effects on Soybean (Glicine max L. Merr.) Yield Under Temperate Climate Conditions

    NASA Astrophysics Data System (ADS)

    László Phd, M., ,, Dr.

    2009-04-01

    -fundamental processes and how to control them. Conference at the Royal Swedish Academy of Agriculture and Forestry. April 12th. 1999. (Ed's Jan Persson). 9-23. Kungl Skogs-och Lantbruksakademiens Tidskrift. Stockholm. Kádár, I. & Márton, L., 1999. Mineral Nutrient Cycle of Soya. Agrochemistry and Soil Science. 48:67-82. Kováts, A., Márton, L. & Szabó, L., 1985. Analysis of the relation between humus and pH on the ground of results of soil investigations on farm-scale plots. Plant Production. 34:507-512. László, M., Silva, J.B.C. & José, A.B., 2001. Ecological friendly dragée technics on different crops and vegetables seeds. Acta Agronomica Óváriensis. 43:9-13. László, M., & Jose, E.M., 2001. Effects of Crotalaria juncea L. and Crotalaria spectabilis ROTH on soil fertility and siol conservation in Hungary. Acta Agronomica Óváriensis. 43:1-8. Márton, L., 2000. Effect of NPK fertilization on potao (Solanum tuberosum L.) yield. Ph.D dissertation. University of Veszprém, Keszthely, 136. p. Márton, L., 2001. Climate change and N, P, K, Mg fertilization effect analysis at Tisza-river basin in a long term field experiment. Szent István University, Gödöllő, 21. p. Márton, L. & Kádár, I., 1998. Effect of nitrogen supplies on the yield components of soya. Plant production. 47:677-687. Reeves, T.G., 1998. Sustainable Intensification of Agriculture. International Maize and Wheat Improvement Center. Mexico city. Mexico. Wilcox, J.R., 1987. Soybeans: Improvement, Production, and Uses. Madison, Wisconsin, USA.

  10. EDITORIAL: Van der Waals interactions in advanced materials, in memory of David C Langreth Van der Waals interactions in advanced materials, in memory of David C Langreth

    NASA Astrophysics Data System (ADS)

    Hyldgaard, Per; Rahman, Talat S.

    2012-10-01

    : potential-energy curves for H2 molecules on Cu(111), (100) and (110) surfacesKyuho Lee, Kristian Berland, Mina Yoon, Stig Andersson, Elsebeth Schröder, Per Hyldgaard and Bengt I Lundqvist Ab initio and semi-empirical van der Waals study of graphene-boron nitride interaction from a molecular point of viewVasile Caciuc, Nicolae Atodiresei, Martin Callsen, Predrag Lazić and Stefan Blügel Rationale for switching to nonlocal functionals in density functional theoryP Lazić, N Atodiresei, V Caciuc, R Brako, B Gumhalter and S Blügel Improved description of soft layered materials with van der Waals density functional theoryGabriella Graziano, Jiří Klimeš, Felix Fernandez-Alonso and Angelos Michaelides Structure and stability of weakly chemisorbed ethene adsorbed on low-index Cu surfaces: performance of density functionals with van der Waals interactionsFelix Hanke, Matthew S Dyer, Jonas Björk and Mats Persson Are we van der Waals ready?T Björkman, A Gulans, A V Krasheninnikov and R M Nieminen Nonequilibrium thermodynamics of interacting tunneling transport: variational grand potential, density functional formulation and nature of steady-state forcesP Hyldgaard