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Caltech Authors (115,846 recursos)
Repository of works by Caltech published authors.

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Mostrando recursos 1 - 20 de 50,479

1. Infrared Observations of Eta Carinae - Neugebauer, G.; Westphal, J. A.
Eta Carinae is a non-stellar object less than 5" in diameter seen projected on a region of dense nebulosity. Spectroscopic observations, reviewed by Rodgers and Searle (1967) and Aller (1966) have shown strong emission lines superimposed on a smooth continuum. This continuum contributes about 60 per cent of the visual energy and rises steeply into the infrared; no entirely satisfactory mechanism for producing this radiation has been proposed. In this Letter photometric data which extend the continuum observations to 1.65, 2.2, and 3.4 μ are presented.

2. The Change of Intensity, Color, Line Strength, and Line Position in the QSS 3C 446 during the 1966 Outburst - Sandage, Allan; Westphal, J. A.; Strittmatter, P. A.
During the course of routine observations of quasi-stellar radio sources, 3C 446 was found to be abnormally bright on June 24.4 U.T., 1966 (Sandage 1966). A further observation on July 12.4 U.T., 1966, confirmed this result, showing that the object had undergone an outburst of at least 3.2 mag. sometime between October 5, 1964, and June 24, 1966. This time interval can be narrowed appreciably because a visual estimate of the V magnitude by Schmidt on September 23 and 25, 1965, gave V not brighter than 18 on those dates. The event is of particular importance as it enables us to make several tests concerning the intensity...

3. Electronic Excitation of Molecules by Electron Impact - McKoy, Vincent; Lee, Mu-Tao
In this talk I will review the recent progress that has been made in the theoretical determination of differential and integral cross sections for the electronic excitation of molecules by low-energy electrons. Whereas there has been considerable progress in the development and application of theoretical methods for treating inelastic electron-atom scattering [1], the situation is quite different for the related molecular problem. It is well-known that this difference is ultimately due to the difficulties associated with the nonspherical nature of the electron-molecule force field. In fact, it was not until the 1960’s that a renewed interest in processes involving H2...

4. On the Dynamic Response of a Beam to a Randomly Moving Load - Knowles, J. K.
The problem considered is that of an infinitely long elastic beam subject to a moving concentrated force whose position is a stochastic function of time, X(t). The expected deflection and expected bending moment are analyzed, with special attention being given to the case of a stationary process X(t) and to the case in which X(t) is a Wiener process.

5. The Feel of the Moon - Scott, Ronald F.
In September Surveyor V showed that the moon's surface is not unlike the earth's in composition. Six months earlier Surveyor III had found that its consistency was also much like a granular terrestrial soil.

6. Glacier Bay: The Land and the Silence [Book Review] - Sharp, Robert P.
Glacier Bay-the name alone calls up an image of spectacular scenery, but imagination must surely fall short of reality. Glacier Bay National Monument extends west from the Chilkat Range to Cape Fairweather (a gross misnomer), and north from Cross Sound to the Canadian border. Within this area of 4319 square miles is a plexus of deep berg-choked fjords, glacier-filled valleys, and snow-clad peaks. Relief ranges from sea level to 15,300 feet.

7. Dynamic Penetration Studies in Crushed Rock under Atmospheric and Vacuum Conditions - Roddy, David J.; Rittenhouse, John B.; Scott, Ronald F.
A device was constructed to study dynamic penetration in crushed rock both in air and a high-vacuum (10^(-5) mm Hg) condition. The apparatus is designed to drop cylindrical, metal rods, pointed on one end, into cohesion-less crushed rock material. Dynamic penetration is studied as a function of several particle sizes and mixtures of these particle sizes. Other factors considered are the density of packing, probe dimensions, vacuum pressure, and vacuum degassing rates. Experimental results show that the density of packing of the crushed rock particles is the dominant factor affecting the dynan1ic penetration. The maximum penetration occurs in air in the crushed rock with low-density packing....

8. Search for a Higgs boson in the mass range from 145 to 1000 GeV decaying to a pair of W or Z bosons - Khachatryan, V.; Anderson, D.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Mott, A.; Newman, H. B.; Pena, C.; Pierini, M.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Dubinin, M.
A search for a heavy Higgs boson in the H → WW and H → ZZ decay channels is reported. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 fb^(−1) at √s =7 TeV and up to 19.7fb^(−1) at √s = 8 TeV, recorded by the CMS experiment at the CERN LHC. Several final states of the H → WW and H → ZZ decays are analyzed. The combined upper limit at the 95% confidence level on the product of the cross section and branching fraction exclude a Higgs boson with...

9. Measurement of initial-state–final-state radiation interference in the processes e^+e^− → μ^+μ^−γ and e^+e^− → π^+π^−γ - Lees, J. P.; Chao, D. S.; Cheng, C. H.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Kim, J.; Miyashita, T. S.; Ongmongkolkul, P.; Porter, F. C.; Röhrken, M.
Charge asymmetry in the processes e^+e^− → μ^+μ^−γ and e^+e− → π^+π^−γ is measured using 232 fb^(−1 of data collected with the BABAR detector at eþe− center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial- and final-state radiation (FSR). The asymmetry is determined as a function of the invariant mass of the final-state tracks from production threshold to a few GeV=c^2. It is compared to the expectation from QED for e^+e^− → μ^+μ^−γ, and from theoretical models for e^+e^− →...

10. The World of Ice [Book Review] - Sharp, Robert P.
This is neither a textbook nor an exhaustive technical treatise on ice. Rather, it is a skillful distillation and integration of the author's extensive reading, covering at least a quarter of a century. The objectives are not specifically stated, but one quickly senses that the book is designed to give an intelligent lay public knowledge and understanding of, and, above all, an interest in, that common substance, ice-what it has done, what it is doing, and what it may do in the future to the world in which we live. Judged in the light of this aim, "The World of Ice" should be highly successful.

11. Shockwaves from Cavity Collapse - Plesset, M. S.
The determination of the stresses produced by cavity collapse has been of interest since Rayleigh's discussion of the problem. One theoretical calculation relating to this problem is the magnitude of the pressure pulse which is radiated when a spherical bubble collapses and rebounds in a liquid. A calculation of this kind has been made although it was necessary to idealize the physical situation. The peak pressures predicted by this treatment were of the order of some thousands of atmospheres and could, therefore, furnish a mechanism for the damage of solid surfaces. Since these peak pressures decrease rapidly with distance from...

12. Transcurrent Faults in Continental Areas - Allen, C. R.
Seismic fault-plane solutions, displacements observed during historic earthquakes, and an increasing number of geological reports of active transcurrent faults in many parts of the world all suggest that transcurrent faulting is a far more important tectonic process than has usually been recognized. Characteristic features of active transcurrent faults-easily overlooked in the absence of aerial photographs-include: abundant Recent scarps that often show a scissoring relationship to one another; elongate closed depressions; consistently offset streams; and unique rift topography that is remarkably linear over distances of hundreds of kilometers. Thrusts that steepen abruptly with depth typify many transcurrent faults at the base...

13. Hand Shape Representations in the Human Posterior Parietal Cortex - Klaes, Christian; Kellis, Spencer; Aflalo, Tyson; Lee, Brian; Pejsa, Kelsie; Shanfield, Kathleen; Hayes-Jackson, Stephanie; Aisen, Mindy; Heck, Christi; Liu, Charles; Andersen, Richard A.
Humans shape their hands to grasp, manipulate objects, and to communicate. From nonhuman primate studies, we know that visual and motor properties for grasps can be derived from cells in the posterior parietal cortex (PPC). Are non-grasp-related hand shapes in humans represented similarly? Here we show for the first time how single neurons in the PPC of humans are selective for particular imagined hand shapes independent of graspable objects. We find that motor imagery to shape the hand can be successfully decoded from the PPC by implementing a version of the popular Rock-Paper-Scissors game and its extension Rock-Paper-Scissors-Lizard-Spock. By simultaneous...

14. Isolation of a Chloramphenicol-Resistant Protein From λ-Infected Cells - Levine, Arnold J.; Sinsheimer, Robert L.
During infection with bacteriophage ϕX174, a protein, made in the presence of 30 γ chloramphenicol/ml but not made in the presence of concentrations greater than 100 γ/ml, has been shown to be essential for viral DNA replication. A protein with similar chromatographic properties and “chloramphenicol resistance” has now been demonstrated in cells infected with λ bacteriophage.

15. The 8-14-μ Appearance of Venus Before the 1964 Conjunction - Westphal, J. A.; Wildey, R. L.; Murray, B. C.
In an earlier paper (Murray, Wildey, and Westphal 1963) we have described the detailed mapping of the 8-14-μ radiation from Venus using the 200-inch Hale telescope. This paper extends that work over a period of about 7 months from December 15, 1963, to June 6, 1964. Detailed maps for 6 days are presented that show the morphology of the upper-atmosphere brightness temperature and illustrate a number of anomalous features near the cusps. The problem of atmospheric extinction and the derived brightness temperature is discussed.

16. Measurement of the ratio of the production cross sections times branching fractions of B^±_c → J/ψπ^± and B^± → J/ψK^± and B(B^±_c → J/ψπ^±π^±π^∓)/B(B^±_c → J/ψπ^±) in pp collisions at √s = 7 TeV - Khachatryan, V.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Mott, A.; Newman, H. B.; Pena, C.; Rogan, C.; Spiropulu, M.; Timciuc, V.; Vlimant, J. R.; Wilkinson, R.; Xie, S.; Zhu, R. Y.; Dubinin, M.
The ratio of the production cross sections times branching fractions (σ(B±c)B(B^±_c → J/ψπ^±))σ(B±)B(B± → J/ψK^±)) is studied in proton-proton collisions at a center-of-mass energy of 7TeV with the CMS detector at the LHC. The kinematic region investigated requires B^±_c and B^± mesons with transverse momentum p_T > 15 GeV and rapidity |y| < 1.6. The data sample corresponds to an integrated luminosity of 5.1 fb^(−1). The ratio is determined to be [0.48 ± 0.05 (stat) ± 0.03 (syst) ± 0.05 (T_B_c)]%. The B^±_c → J/ψπ^±π^±π^∓ decay is also observed in the same data sample. Using a model-independent method developed to measure the...

17. Dynamic Photoelastic Studies of P and S Wave Propagation in Prestressed Media - Thomson, Ker C.; Ahrens, Thomas J.; Toksöz, M. Nafi
The occasional existence of very pronounced, anomalous, horizontally polarized seismic waves from underground nuclear bomb blasts has been reported by several investigators. In order to further understanding of this phenomenon and the processes of mechanical radiation from explosions, particularly in prestressed media, a model study has been undertaken. Experimental apparatus has been developed which permits the generation and propagation of body waves from explosions in transparent plate models prestressed to various two-dimensional stress configurations. High-speed framing camera sequences are presented showing the explosion process and the resulting plate compressional and shear wave propagation in prestressed models. These are compared to...

18. Conformations of the Single-Stranded DNA of Bacteriophage M13 - Forsheit, Arleen B.; Ray, Dan S.
At least two conformations of M13 single-stranded DNA have been demonstrated by measuring differences in sedimentation coefficient and by direct visualization in the electron microscope. Which form is obtained from infected cells and/or intact phage depends on the pH, ionic strength, and temperature. The slower-sedimenting form can be converted to the faster-sedimenting, single-stranded form by low ionic strength, alkali treatment, formamide, or formaldehyde, but not by exposure to 100°C in 1.0 M NaCl. The ability to assume either conformation appears to be a function of the nucleic acid alone. Whether or not these different conformations are of biological significance is still unknown.

19. Two Transiting Earth-size Planets Near Resonance Orbiting a Nearby Cool Star - Petigura, Erik A.; Schlieder, Joshua E.; Crossfield, Ian J. M.; Howard, Andrew W.; Deck, Katherine M.; Ciardi, David R.; Sinukoff, Evan; Allers, Katelyn N.; Best, William M. J.; Liu, Michael C.; Beichman, Charles A.; Isaacson, Howard; Sinukoff, Brad M. S.; Lépine, Sébastien
Discoveries from the prime Kepler mission demonstrated that small planets (<3 R_⊕) are common outcomes of planet formation. While Kepler detected many such planets, all but a handful orbit faint, distant stars and are not amenable to precise follow up measurements. Here, we report the discovery of two small planets transiting K2-21, a bright (K = 9.4) M0 dwarf located $65\pm 6$ pc from Earth. We detected the transiting planets in photometry collected during Campaign 3 of NASA's K2 mission. Analysis of transit light curves reveals that the planets have small radii compared to their host star, R_P/R_* = 2.60...

20. Model-reduced variational fluid simulation - Liu, Beibei; Mason, Gemma; Hodgson, Julian; Tong, Yiying; Desbrun, Mathieu
We present a model-reduced variational Eulerian integrator for incompressible fluids, which combines the efficiency gains of dimension reduction, the qualitative robustness of coarse spatial and temporal resolutions of geometric integrators, and the simplicity of sub-grid accurate boundary conditions on regular grids to deal with arbitrarily-shaped domains. At the core of our contributions is a functional map approach to fluid simulation for which scalar- and vector-valued eigenfunctions of the Laplacian operator can be easily used as reduced bases. Using a variational integrator in time to preserve liveliness and a simple, yet accurate embedding of the fluid domain onto a Cartesian grid,...

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