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Caltech Authors (96,904 recursos)
Repository of works by Caltech published authors.

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Mostrando recursos 1 - 20 de 37,808

1. The loss of atmosphere from Mars - Response - Johnson, R. E.; Liu, M.; Kass, D. M.; Yung, Y. L.
The results presented in our report (1) indicated that it was necessary to consider dissociation during all collisions in calculating the atmospheric loss from Mars that results from sputtering. With the use of the newly calculated cross sections presented by Johnson and Liu in our model, we find that Mars has lost about 1 bar of CO_2. The revised cross sections reduce our sputtering yields (Table 1), but do not bring our results into agreement with Luhmann et al. (2) and Jakosky et al. (3).

2. Review of Particle Physics - Olive, K. A.; Golwala, S.; Vogel, P.; Zhu, R. Y.
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,283 new measurements from 899 Japers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as heavy neutrinos, supersymmetric and technicolor particles, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Supersymmetry, Extra Dimensions, Particle Detectors, Probability, and Statistics. Among the 112 reviews are many that...

3. Acetylene on Titan - Reply - Matteson, Donald S.; Lunine, Jonathan I.; Stevenson, David J.; Yung, Yuk L.
We acknowledge the rather explosive properties of pure, solid acetylene, as noted by Matteson. However, we envision the composition of the solid material underlying the ethane-methane ocean to be considerably more complicated than pure acetylene, as we suggest briefly in our report. The dissociation of methane and consequent production of hydrocarbons in the Titan stratosphere from methane must produce not only C_2 and C_3 hydrocarbons but also much heavier long-chain polymers (incorporating nitrogen), at the expense, in part, of acetylene.

4. Ultraviolet spectrometer experiment for the Voyager mission - Broadfoot, A. L.; Sandel, B. R.; Shemansky, D. E.; Atreya, S. K.; Donahue, T. M.; Moos, H. W.; Bertaux, J. L.; Blamont, J. E.; Ajello, J. M.; Strobel, D. F.; McConnell, J. C.; Dalgarno, A.; Goody, R.; McElroy, M. B.; Yung, Y. L.
The Voyager Ultraviolet Spectrometer (UVS) is an objective grating spectrometer covering the wavelength range of 500–1700 Å with 10 Å resolution. Its primary goal is the determination of the composition and structure of the atmospheres of Jupiter, Saturn, Uranus and several of their satellites. The capability for two very different observational modes have been combined in a single instrument. Observations in the airglow mode measure radiation from the atmosphere due to resonant scattering of the solar flux or energetic particle bombardment, and the occultation mode provides measurements of the atmospheric extinction of solar or stellar radiation as the spacecraft enters...

5. Receptive Fields of Disparity-Tuned Simple Cells in Macaque V1 - Tsao, Doris Y.; Conway, Bevil R.; Livingstone, Margaret S.
Binocular simple cells in primary visual cortex (V1) are the first cells along the mammalian visual pathway to receive input from both eyes. Two models of how binocular simple cells could extract disparity information have been put forward. The phase-shift model proposes that the receptive fields in the two eyes have different subunit organizations, while the position-shift model proposes that they have different overall locations. In five fixating macaque monkeys, we recorded from 30 disparity-tuned simple cells that showed selectivity to the disparity in a random dot stereogram. High-resolution maps of the left and right eye receptive fields indicated that...

6. Long-lasting neurotrophin-induced enhancement of synaptic transmission in the adult hippocampus - Kang, Hyejin; Schuman, Erin M.
The neurotrophins are signaling factors important for the differentiation and survival of distinct neuronal populations during development. To test whether the neurotrophins also function in the mature nervous system, the effects of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and neurotrophic factor 3 (NT-3) on the strength of synaptic transmission in hippocampal slices were determined. Application of BDNF or NT-3 produced a dramatic and sustained (2 to 3 hours) enhancement of synaptic strength at the Schaffer collateral-CA1 synapses; NGF was without significant effect. The enhancement was blocked by K252a, an inhibitor of receptor tyrosine kinases. BDNF and NT-3 decreased...

7. The trithorax gene, a trans-acting regulator of the bithorax complex in Drosophila, encodes a protein with zinc-binding domains - Mazo, Alexander M.; Huang, Der-Hwa; Mozer, Brian A.; Dawid, Igor B.
The trithorax (trx) gene functions in segment determination in Drosophila through interaction with genes of the bithorax complex and Antennapedia complex. Genetic evidence suggests that trx may be considered a positive regulator of homeotic genes. Sequencing of cDNAs corresponding to the entire trx transcription unit revealed the existence of an unusually long open reading frame encoding 3759 amino acids. The main features of the predicted trx protein are several cysteine-rich regions which can be folded into zinc finger-like domains. Cysteine-rich portions expressed from trx cDNAs in Escherichia coli are capable of zinc binding in vitro, suggesting a possible function for...

8. Scanning Electron Microscopy and X-Ray Microanalysis [Book Review] - Albee, Arden L.
This outstanding volume has managed the nearly impossible task of combining the expertise of all six authors in a lucid and homogeneous style of writing. Subtitled ‘A Text for Biologists, Material Scientists and Geologists,’ the book has evolved from a short course taught each summer at Lehigh University. The book provides a basic knowledge of (1) the electron optics for these instruments a nd their controls, (2) the characteristics of the electron beam-sample interactions, (3) image formation and interpretation, (4) X ray spectrometry and quantitative X ray microanalysis with separate detailed sections on wavelength dispersive and energy dispersive techniques, and (5)...

9. Contributions of Bird Studies to Biology - Konishi, Masakazu; Emlen, Stephen T.; Ricklefs, Robert E.; Wingfield, John C.
Birds are widely distributed, highly diversified, and exhibit behavior and social organizations equal in complexity to mammals, yet they are generally more conspicuous and approachable in natural environments. These attributes make birds excellent subjects in many areas of biological research. The topics in which studies on birds have figured prominently include the mechanisms of species formation, the regulation of the distribution and abundance of animals, the effects of the environment on behavior and physiology, the biological and evolutionary significance of variations in social organizations, the encoding of information in animal communication, the sensory basis for migration and navigation, the effects...

10. Similarity of sli-1, a regulator of vulval development in C. elegans, to the mammalian proto-oncogene c-cbl - Yoon, Charles H.; Lee, Junho; Jongeward, Gregg D.; Sternberg, Paul W.
Vulval induction during Caenorhabditis elegans development is mediated by LET-23, a homolog of the mammalian epidermal growth factor receptor tyrosine kinase. The sli-1 gene is a negative regulator of LET-23 and is shown here to encode a protein similar to c-Cbl, a mammalian proto-oncoprotein. SLI-1 and c-Cbl share approximately 55 percent amino acid identity over a stretch of 390 residues, which includes a C_3HC_4 zinc-binding motif known as the RING finger, and multiple consensus binding sites for Src homology 3 (SH3) domains. SLI-1 and c-Cbl may define a new class of proteins that modify receptor tyrosine kinase-mediated signal transduction.

11. A ratiometric-based measure of gene co-expression - Abelin, Anna C. T.; Marinov, Georgi K.; Williams, Brian A.; McCue, Kenneth; Wold, Barbara J.
Background: Gene co-expression analysis has previously been based on measures that include correlation coefficients and mutual information, as well as newcomers such as MIC. These measures depend primarily on the degree of association between the RNA levels of two genes and to a lesser extent on their variability. They focus on the similarity of expression value trajectories that change in like manner across samples. However there are relationships of biological interest for which these classical measures are expected to be insensitive. These include genes whose expression levels are ratiometrically stable and genes whose variance is tightly constrained. Large-scale studies of relatively...

12. Researches on Insulin - Abel, John J.; Geiling, E. M. K.; Alles, G.; Raymond, A.
In the early autumn of 1924 we were invited by Professor A. A. Noyes, director of the Gates Chemical Laboratory of the California Institute of Technology, Pasadena, California, to investigate the chemical and other properties of insulin in his laboratory under a grant from the Carnegie Foundation. Commercial insulin as prepared by the Lilly Research Laboratories of Eli Lilly and Company, Indianapolis, Indiana, has served as the material for our investigation. Two forms of commercial insulin have been used by us; one a dry powder evaluated at approximately 8 rabbit units per milligram; the second a highly concentrated aqueous solution...

13. Wave transmission in time- and space-variant helicoidal phononic crystals - Li, F.; Chong, C.; Yang, J.; Kevrekidis, P. G.; Daraio, C.
We present a dynamically tunable mechanism of wave transmission in one-dimensional helicoidal phononic crystals in a shape similar to DNA structures. These helicoidal architectures allow slanted nonlinear contact among cylindrical constituents, and the relative torsional movements can dynamically tune the contact stiffness between neighboring cylinders. This results in cross-talking between in-plane torsional and out-of-plane longitudinal waves. We numerically demonstrate their versatile wave mixing and controllable dispersion behavior in both wavenumber and frequency domains. Based on this principle, a suggestion toward an acoustic configuration bearing parallels to a transistor is further proposed, in which longitudinal waves can be switched on and...

14. A Far-Infrared Spectroscopic Survey of Intermediate Redshift (Ultra) Luminous Infrared Galaxies - Magdis, Georgios E.; Rigopoulou, D.; Hopwood, R.; Huang, J.-S.; Farrah, D.; Pearson, C.; Alonso-Herrera, Almudena; Bock, J. J.; Clements, D.; Cooray, A.; Griffin, M. J.; Oliver, S.; Perez-Fournon, I.; Riechers, D.; Swinyard, B. M.; Scott, D.; Thatte, N.; Valtchanov, I.; Vaccari, M.
We present Herschel far-IR photometry and spectroscopy as well as ground-based CO observations of an intermediate redshift (0.21 ≤ z ≤ 0.88) sample of Herschel-selected (ultra)-luminous infrared galaxies (L_(IR) > 10^(11.5) L_☉). With these measurements, we trace the dust continuum, far-IR atomic line emission, in particular [C II] 157.7 μm, as well as the molecular gas of z ~ 0.3 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) and perform a detailed investigation of the interstellar medium of the population. We find that the majority of Herschel-selected intermediate redshift (U)LIRGs have L_(CII)/L_(FIR) ratios that are a factor of about 10...

15. Neuroimaging Weighs In: Humans Meet Macaques in “Primate” Visual Cortex - Tootell, Roger B. H.; Tsao, Doris; Vanduffel, Wim
It has been only a decade since functional magnetic resonance imaging (fMRI) was introduced, but approximately four fMRI papers are now published every working day. Here we review this progress in a well studied system: primate visual cortex.

16. Paleontological and Geological Investigations in the John Day Region of Eastern Oregon - Buwalda, John P.
A coordinated program of research, rather unique in the range and detailed nature of the studies included in it, is being conducted in the John Day region of eastern Oregon. Through investigations in vertebrate and invertebrate paleontology, paleobotany and physical geology, an attempt is being made to construct as completely as possible the history of the development of animal and plant life and of geologic and climatic changes in this part of the northwest in the later eras of geologic time.

17. Algebraic renormalization and Feynman integrals in configuration spaces - Ceyhan, Özgür; Marcolli, Matilde
This paper continues our previous study of Feynman integrals in configuration spaces and their algebro-geometric and motivic aspects. We consider here both massless and massive Feynman amplitudes, from the point of view of potential theory. We consider a variant of the wonderful compactification of configuration spaces that works simultaneously for all graphs with a given number of vertices and that also accounts for the external structure of Feynman graph. As in our previous work, we consider two version of the Feynman amplitude in configuration space, which we refer to as the real and complex versions. In the real version, we...

18. The Electrical Specific Action to Melt of Structural Copper and Aluminum Alloys - Vanderburg, Andrew; Stefani, Francis; Sitzman, Alex; Crawford, Mark; Surls, Dwayne; Ling, Chloe; McDonald, Jason
This paper describes an exploding wire experiment to measure the electrical specific action to melt of structural alloys of copper and aluminum, including C10100, C11000, C18000, C18200, Al6061, and Al7075. These alloys, which are commonly used in railguns and other pulsed power devices, are not produced in fine wire form. Instead of wires, we developed a technique to test macroscopic samples (0.25 mm × 0.5 mm cross section) manufactured with wire electrical discharge machining. This paper includes a description of the design considerations for such macroscopic exploding wire experiments.

19. Kepler Eclipsing Binary Stars. V. Identification of 31 Candidate Eclipsing Binaries in the K2 Engineering Dataset - Conroy, Kyle E.; Prša, Andrej; Stassun, Keivan G.; Bloemen, Steven; Parvizi, Mahmoud; Quarles, Billy; Boyajian, Tabetha; Barclay, Thomas; Shporer, Avi; Latham, David W.; Abdul-Masih, Michael
Over 2500 eclipsing binaries were identified and characterized from the ultraprecise photometric data provided by the Kepler space telescope. Kepler is now beginning its second mission, K2, which is proving to again provide ultraprecise photometry for a large sample of eclipsing binary stars. In the 1951 light curves covering 12 days in the K2 engineering dataset, we have identified and determined the ephemerides for 31 candidate eclipsing binaries that demonstrate the capabilities for eclipsing binary science in the upcoming campaigns in K2. Of those, 20 are new discoveries. We describe both manual and automated approaches to harvesting the complete set...

20. The Finding of Pleistocene Material in an Asphalt Pit at Carpinteria, California - Hoffmann, Ralph; Stock, Chester; Miller, Loye; Chaney, Ralph W.; Mason, Herbert L.
In February, 1927, on the Lucien Higgins ranch in Carpinteria in southern Santa Barbara County, California, a steam-shovel which was taking out road material over a deposit of asphalt disclosed some bones. These were brought to the attention of Mr. Norton Stuart, curator of the Santa Barbara Museum of Natural History. Mr. Stuart at once began an investigation of the field and after several attempts to locate the source of the earlier finds, at last discovered a mass of material which extends to a depth that has not yet been measured. Here, Mr. Stuart found a great number of bones...

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