71,165 research outputs found
Geologic atlas of the United States : topography, areal geology, economic geology, structure sections / 70 Washington Folio : District of Columbia - Maryland - Virginia
No full textN. H. Darton ; Arthur Keith; H. M. Wilson ; J. D. Hoffman ; D. J. Howell ; A. E. Murlin ; J. H. Jennings ; M. Hackett ; W. M. Beaman ; H. Munroe ; A. Pike ; R. Muldrow ; W. J. Lloyd ; J. W. Thom ; A. M. Walker ; E. B. Clark ; G. E. HydeList of Sheets: Topography, Historical Geology, Economic Geology, Structure Sections, Physiographic GeologyIndirektes handschriftliches Exlibris: "1901, 594", das ist Geological Survey U. S. Washington Exemplar der ETH-BI
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Letter from Carl Hayden to M. J. Riordan
No full textLetter from Carl Hayden to M. J. Riordan expressing his support for Coconino County in turning over the Bright Angel Trail to the federal government
Glass formation in upper tropospheric aerosol particles
No full textPedernera de Neuhaus DA. Glasbildung in Aerosolpartikeln der oberen Troposphäre. Bielefeld (Germany): Bielefeld University; 2008.Over the last two decades the chemical composition of atmospheric aerosols has changed significantly. Recent field measurements have shown that atmospheric aerosol particles in the upper tropical troposphere contain increasing quantities of organic solutes. At the same time it has been observed that in those aerosols the formation of cirrus clouds is inhibited.
In this work a new process is presented, that might retard or even entirely impede ice nucleation, ice growth as well as the water uptake of atmospheric aerosol particles in the upper troposphere: the formation of glassy aerosol particles.
The glass transition temperatures, Tg, homogeneous ice nucleation temperatures, Thom, and ice melting temperatures, Tm, of various aqueous organic, inorganic and mixed solutions were investigated with a differential scanning calorimeter. The following water-soluble compounds were investigated in binary and ternary aqueous solutions with different mass mixing ratios: glucose, levoglucosan, glutaric acid, 1,4-butanediol, H2SO4, NH4NO3, NH4HSO4, Ca(NO3)2 and NaNO3.
The results of these experiments are presented by means of state diagrams. They reveal that aqueous solutions containing atmospherically relevant inorganic solutes such as NH4NO3 or H2SO4 exhibit only very low Tg-values below 180 K. Therefore, it is expected that atmospheric aerosol particles of such inorganic solutions exist in the liquid or in the crystalline state, but not as glasses. In contrast, aqueous solutions of the investigated organic compounds tend to form glasses at atmospherically relevant temperatures.
In order to apply the laboratory data to the atmospheric situation, the measured phase transition temperatures Tg, Thom and Tm were transformed from the concentration scale to the water activity scale by parameterizing water activities determined experimentally.
The results show that both ice nucleation and ice growth in aqueous organic-enriched aerosol particles can be considerably reduced or even completely inhibited, which can explain the observed inhibition of cirrus cloud formation in the upper tropical troposphere.Im Laufe der letzten zwei Jahrzehnte hat sich die Zusammensetzung atmosphärischer Aerosole stark verändert. Feldmessungen haben kürzlich gezeigt, dass atmosphärische Aerosolpartikel der oberen tropischen Troposphäre immer größere Mengen an organischen Substanzen enthalten. Gleichzeitig wurde in diesen Aerosolen eine Hemmung der Eiswolkenbildung beobachtet.
In dieser Arbeit wird ein neuer Mechanismus präsentiert, welcher die Eisnukleation, das Eiswachstum und die Wasseraufnahme in atmosphärischen Aerosolpartikeln unter den in der oberen Troposphäre herrschenden Bedingungen (wie etwa Temperaturen zwischen 180 und 200 K) verlangsamen oder verhindern kann: die Bildung glasartiger Aerosolpartikel.
Die Temperatur der Glasumwandlung, Tg, der homogenen Eisnukleation, Thom, und des Eisschmelzens, Tm, diverser wässriger Systeme aus organischen und/oder anorganischen Substanzen wurde mittels dynamischer Kalorimetrie experimentell bestimmt. Die Substanzen Glucose, Levoglucosan, Glutarsäure, 1,4-Butandiol, H2SO4, NH4NO3, NH4HSO4, Ca(NO3)2 und NaNO3 wurden dabei in verschiedenen Massenverhältnissen in binären und ternären wässrigen Lösungen untersucht.
Die aus diesen Messungen erhaltenen Phasendiagramme zeigen, dass wässrige Lösungen aus atmosphärisch relevanten anorganischen Substanzen wie H2SO4 oder NH4NO3 nur sehr niedrige Tg-Werte unterhalb 180 K aufweisen. Es ist daher zu erwarten, dass die entsprechenden atmosphärischen Aerosolpartikel im flüssigen oder im kristallinen Zustand vorliegen, nicht jedoch als Glas. Dagegen neigen wässrige Lösungen der untersuchten organischen Verbindungen zu einer Glasbildung.
Um diese im Labor experimentell bestimmten Daten auf die Atmosphäre anwenden zu können, wurden die Temperaturen Tg, Thom und Tm von der Konzentrationsskala mit Hilfe von Messungen und entsprechenden Parametrisierungen in die Wasseraktivitätsskala umgewandelt.
Die Ergebnisse zeigen, dass sowohl die Eisnukleation als auch das Eiswachstum in wässrigen organischen Aerosolpartikeln erheblich reduziert oder gar vollständig unterbunden werden können, was die beobachtete Hemmung der Eiswolkenbildung in der oberen tropischen Troposphäre erklären kann
Gastrocnemius muscle-tendon behaviour during walking in young and older adults
No full textAim: Age-related differences in muscle architectural and tendon mechanical properties have been observed in vivo under static conditions and during single joint contractions. The aim of this study was to determine if there are age-related differences in gastrocnemius fascicle-tendon interactions during a fundamental locomotor task - walking. Methods: Eight young adults (YA; 27 ± 4 years) and eight older adults (OA; 77 ± 4 years) walked on a treadmill at 1.11 m s-1 whilst length changes in the gastrocnemius lateralis muscle tendon complex (MTC), fascicles and tendinous tissue (TT) were determined from joint angles, ultrasonography and a geometric MTC model (combining MTC and fascicle measurements) respectively. Results: There was no age-related difference in lengthening of the MTC during stance. However, the fascicle and TT contribution to MTC lengthening was altered; TT lengthening was larger in OA than in YA (P = 0.05) and fascicle lengthening was less in OA than YA (P < 0.05). There were no differences between groups in MTC, fascicle or TT shortening amplitude during push-off. Conclusion: The observations are consistent with previous reports of increased compliance of TT in older adults. © 2007 The Authors
Letter from M. J. Riordan, Arizona Lumber and Timber Company, to Carl Hayden
No full textLetter from M. J. Riordan to Carl Hayden expressing his opposition to the federal government's takeover of Bright Angel Trail
Metabolic cost, mechanical work, and efficiency during walking in young and older men
No full textAim: To investigate mechanical work, efficiency, and antagonist muscle co-activation with a view to better understand the cause of the elevated metabolic cost of walking (CW) in older adults. Methods: Metabolic, mechanical and electromyographic measurements were made as healthy young (YOU; n = 12, age = 27 ± 3 years) and older (OLD; n = 20, age = 74 ± 3 years) men of equivalent body mass and leg length walked on a treadmill at four speeds (ranging from 0.83 to 1.67 m s-1). Results: Net (above resting) CW, determined by indirect calorimetry was 31% higher (average across speeds) in OLD (P < 0.05). The integrity of the passive pendulum like interchange of mechanical energies of the centre of mass (COM B), an energy-saving mechanism, was maintained in OLD. Furthermore, total mechanical work, determined from fluctuations in mechanical energy of COMB and of body segments relative to COMB, was not significantly elevated in OLD. This resulted in a lower efficiency in OLD (-17%, P < 0.05). Co-activation, temporally quantified from electromyography recordings, was 31% higher in OLD for antagonist muscles of the thigh (P < 0.05). Thigh co-activation was moderately correlated with CW at three speeds (r = 0.38-0.52, P < 0.05). Conclusion: Healthy septuagenarians with no gait impairment have an elevated CW which is not explained by an elevation in whole body mechanical work. Increased antagonist muscle co-activation (possibly an adaptation to ensure adequate joint stability) may offer partial explanation of the elevated CW. © 2006 Scandinavian Physiological Society
E. J. Hughes
No full textThom surveys Hughes’ career from the 1930s to 2002 in this book produced in conjunction with a major retrospective of the artist’s work. A portrait of Hughes’ peripatetic life in British Columbia and elsewhere, it includes an account of his experience as a war artist and focuses on the significant influence of his dealer, Max Stern, and their correspondence. Bibliography (1 p.) and chronology (1 p.) 2 maps. Index of works. Circa 100 bibl. ref
Changes in triceps surae muscle architecture with sarcopenia
No full textAim: To investigate whether sarcopenia was evenly distributed among the three components of the triceps surae (TS) muscle group. Methods: Muscle volume (VOL), fibre fascicle length (Lf), pennation angle (θ) and physiological cross-sectional area (PCSA = VOL/Lf) were measured in vivo for the lateral (GL) and medial (GM) heads of the gastrocnemius muscles and for the soleus muscle (SOL), in 15 young males (YM, aged 25.3 ± 4.5 years) and 12 elderly males (EM aged 73.8 ± 4.4 years). Results: In the EM, VOL of all three muscles was significantly smaller than in the YM; differences were: 27% for the GL (P < 0.01), 29% for the GM (P < 0.01) and 17% for the SOL (P < 0.05). In total, TS VOL was 22% smaller in EM than in YM (P < 0.01). In the EM, values of θ were significantly smaller than in the YM; by 15-18% for the GL, GM and SOL (P < 0.05). In the EM, Lf of the GM was 16% smaller than in the YM (P < 0.01); no significant differences were found in the other muscles. PCSA of the GL and GM were both found to be smaller in EM by 19% (P < 0.01) and 14.5% (P < 0.05), respectively. No difference was observed in the SOL PCSA between YM and EM. Interestingly, probably because of the prevalent contribution of the SOL to PCSA distribution of each muscle to the TS PCSA, the relative TS PCSA was not different between YM and EM. Furthermore, the Lf/muscle length ratio did not differ between YM and EM. Conclusion: The present study shows that the relative PCSA composition of the TS is maintained with ageing and that the PCSA is scaled down harmonically with the decrease in muscle volume and fascicle length. Such observation suggests that the relative contribution of the components of the TS muscle to the total force developed by this muscle group is maintained with ageing. © 2005 Scandinavian Physiological Society
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
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