Repository of works by Caltech published authors.
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Mostrando recursos 1 - 20 de 31.609
The evolution of the dust temperatures of galaxies in the SFR–M_∗ plane up to z ~ 2 - Magnelli, B.; Bock, J.
We study the evolution of the dust temperature of galaxies in the SFR− M∗ plane up to z ~ 2 using far-infrared and submillimetre observations from the Herschel Space Observatory taken as part of the PACS Evolutionary Probe (PEP) and Herschel Multi-tiered Extragalactic Survey (HerMES) guaranteed time key programmes. Starting from a sample of galaxies with reliable star-formation rates (SFRs), stellar masses (M_∗) and redshift estimates, we grid the SFR− M_∗parameter space in several redshift ranges and estimate the mean dust temperature (T_(dust)) of each SFR–M_∗ − z bin. Dust temperatures are inferred using the stacked far-infrared flux densities (100–500 ...
Planck intermediate results XIII. Constraints on peculiar velocities - Ade, P. A. R.; Bock, J. J.; Doré, O.; Hildebrandt, S. R.; Rusholme, B.; Crill, B. P.
Using Planck data combined with the Meta Catalogue of X-ray detected Clusters of galaxies (MCXC), we address the study of peculiar motions by searching for evidence of the kinetic Sunyaev-Zeldovich effect (kSZ). By implementing various filters designed to extract the kSZ generated at the positions of the clusters, we obtain consistent constraints on the radial peculiar velocity average, root mean square (rms), and local bulk flow amplitude at different depths. For the whole cluster sample of average redshift 0.18, the measured average radial peculiar velocity with respect to the cosmic microwave background (CMB) radiation at that redshift, i.e., the kSZ...
Anthracyclines Induce DNA Damage Response-Mediated Protection against Severe Sepsis - Figueiredo, Nuno; Zhao, Jimmy L.; Baltimore, David
Severe sepsis remains a poorly understood systemic inflammatory condition with high mortality rates and limited therapeutic options in addition to organ support measures. Here we show that the clinically approved group of anthracyclines acts therapeutically at a low dose regimen to confer robust protection against severe sepsis in mice. This salutary effect is strictly dependent on the activation of DNA damage response and autophagy pathways in the lung, as demonstrated by deletion of the ataxia telangiectasia mutated (Atm) or the autophagy-related protein 7 (Atg7) specifically in this organ. The protective effect of anthracyclines occurs irrespectively of pathogen burden, conferring disease...
Rapid Earthquake Characterization Using MEMS Accelerometers
and Volunteer Hosts Following the M 7.2 Darfield, New Zealand, Earthquake - Lawrence, Jesse F.; Cochran, Elizabeth S.; Chung, Angela; Kaiser, Anna; Christensen, Carl M.; Allen, Richard; Baker, Jack W.; Fry, Bill; Heaton, Thomas; Kilb, Deborah; Kohler, Monica D.; Taufer, Michela
We test the feasibility of rapidly detecting and characterizing earthquakes with the Quake‐Catcher Network (QCN) that connects low‐cost microelectromechanical systems accelerometers to a network of volunteer‐owned, Internet‐connected computers. Following the 3 September 2010 M 7.2 Darfield, New Zealand, earthquake we installed over 180 QCN sensors in the Christchurch region to record the aftershock sequence. The sensors are monitored continuously by the host computer and send trigger reports to the central server. The central server correlates incoming triggers to detect when an earthquake has occurred. The location and magnitude are then rapidly estimated from a minimal set of received ground‐motion parameters....
Developing Image Processing Meta-Algorithms with Data Mining of Multiple Metrics - Leung, Kelvin; Cunha, Alexandre; Toga, A. W.; Parker, D. Stott
People often use multiple metrics in image processing, but here we take a novel approach of mining the values of batteries of metrics on image processing results. We present a case for extending image processing methods to incorporate automated mining of multiple image metric values. Here by a metric we mean any image similarity or distance measure, and in this paper we consider intensity-based and statistical image measures and focus on registration as an image processing problem. We show how it is possible to develop meta-algorithms that evaluate different image processing results with a number of different metrics and mine...
Process Simulation and Control Optimization of a Blast Furnace Using Classical Thermodynamics Combined to a Direct Search Algorithm - Harvey, Jean-Phillipe; Gheribi, Aïmen
Several numerical approaches have been proposed in the literature to simulate the behavior of modern blast furnaces: finite volume methods, data-mining models, heat and mass balance models, and classical thermodynamic simulations. Despite this, there is actually no efficient method for evaluating quickly optimal operating parameters of a blast furnace as a function of the iron ore composition, which takes into account all potential chemical reactions that could occur in the system. In the current study, we propose a global simulation strategy of a blast furnace, the 5-unit process simulation. It is based on classical thermodynamic calculations coupled to a direct...
Perturbations to the Ubiquitin Conjugate Proteome in Yeast Δubx Mutants Identify Ubx2 as a Regulator of Membrane Lipid Composition - Kolawa, Natalie; Sweredoski, Michael J.; Graham, Robert L. J.; Oania, Robert; Hess, Sonja; Deshaies, Raymond J.
Yeast Cdc48 (p97/VCP in human cells) is a hexameric AAA ATPase that is thought to use ATP hydrolysis to power the segregation of ubiquitin-conjugated proteins from tightly bound partners. Current models posit that Cdc48 is linked to its substrates through adaptor proteins, including a family of seven proteins (13 in human) that contain a Cdc48-binding UBX domain. However, few substrates for specific UBX proteins are known, and hence the generality of this hypothesis remains untested. Here, we use mass spectrometry to identify ubiquitin conjugates that accumulate in cdc48 and ubx mutants. Different ubx mutants exhibit unique patterns of conjugate accumulation...
Effect of dry oxidation on the energy gap and chemical composition of CVD graphene on nickel - Aria, Adrianus I.; Gani, Adi W.; Gharib, Morteza
The findings presented herein show that the electronic properties of CVD graphene on nickel can be altered from metallic to semiconducting by introducing oxygen adsorbates via UV/ozone or oxygen plasma treatment. These properties can be partially recovered by removing the oxygen adsorbates via vacuum annealing treatment. The effect of oxidation is studied by scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS). As probed by STM/STS, an energy gap opening of 0.11–0.15 eV is obtainable as the oxygen/carbon atomic ratio reaches 13–16%. The corresponding XPS spectra show a significant monotonic increase in the concentration of oxygenated functional groups due to...
L∞-Multivariate approximation theory - Schultz, Martin H.
This paper is concerned with multivariate analogues of
many standard results in the L∞-approximation theory of functions of one real variable, cf. , , , ,  and . In particular, asymptotic bounds are given for the distance of a given smooth function from various finite-dimensional spaces such as multivariate trigonometric polynomials, multivariate algebraic polynomials and multivariate polynomial spline functions.
Fe^(2+)-Ti^(4+) charge transfer in stoichiometric Fe^(2+),Ti^(4+) -minerals - Mattson, Stephanie M.; Rossman, George R.
Optical absorption spectra are presented for taramellite, traskite and neptunite, all of which have both Fe^(2+) and Ti^(4+) as major elements. The spectra of each of these minerals are dominated by a single, intense absorption band in the 415 to 460 nm region with 7000 to 9000 cm^(−1) half width. These transitions, assigned to Fe^(2+)-Ti^(4+) intervalence charge transfer, showed little difference in intensity at 80 and 300 K and have molar absorptivities which range from ∼100 to ∼1300 M^(−1) cm^(−1). The Fe^(2+)-Ti^(4+) absorptions in these standards generally compare well to other mineral spectra in which Fe^(2+) — Ti^(4+) intervalence absorption...
Genetic Control of Wiring Specificity in the Fly Olfactory System - Hong, Weizhe; Luo, Liqun
Precise connections established between pre- and postsynaptic partners during development are essential for the proper function of the nervous system. The olfactory system detects a wide variety of odorants and processes the information in a precisely connected neural circuit. A common feature of the olfactory systems from insects to mammals is that the olfactory receptor neurons (ORNs) expressing the same odorant receptor make one-to-one connections with a single class of second-order olfactory projection neurons (PNs). This represents one of the most striking examples of targeting specificity in developmental neurobiology. Recent studies have uncovered central roles of transmembrane and secreted proteins...
Fe^(2+)-Fe^(3+) interactions in tourmaline - Mattson, Stephanie M.; Rossman, George R.
The color and spectroscopic properties of ironbearing tourmalines (elbaite, dravite, uvite, schorl) do not vary smoothly with iron concentration. Such behavior has often been ascribed to intervalence charge transfer between Fe^(2+) and Fe^(3+) which produces a new, intense absorption band in the visible portion of the spectrum. In the case of tourmaline, an entirely different manifestation of the interaction between Fe^(2+) and Fe^(3+) occurs in which the Fe^(2+) bands are intensified without an intense, new absorption band. At low iron concentrations, the intensity of light absorption from Fe^(2+) is about the same for E∥c and E⊥c polarizations, but at high...
Ferric Iron in Tourmaline - Mattson, Stephanie M.; Rossman, George R.
Red Fe^(3+)-rich and black Fe^(3+), Fe^(2+)-rich tourmalines have been studied by optical and Mössbauer spectroscopies to determine the optical characteristics of Fe^(3+) in tourmaline. Prominent optical absorption features at 485 and 540 nm are assigned to transitions of multiple exchange-coupled Fe^(3+) pairs in several site combinations. These transitions are more intense than those of isolated Fe^(3+) and are polarized along the vector between the interacting ions, thus permitting site assignments. The 485 nm band occurs at an unusually low energy for Fe^(3+) in silicate minerals. Similar behavior has been observed in the spectrum of coalingite, Mg_(10)Fe_2^(3+) (OH)_(24)CO_(3)·2H_2O, in which Fe^(3+)...
New data on Lotharmeyerite - Kampf, Anthony R.; Shigley, James E.; Rossman, George R.
The new species lotharmeyerite from the Ojuela mine, Mapimi,
Durango, Mexico was recently described by Dunn (1983). Unfortunately,
the very small crystals in drusy growths which that author
had at his disposal did not permit the determination of a number of
important characteristics. The availability of larger, individual
crystals from the same locality now makes possible a more complete
description of the species.
Dynamic Right-Sizing for Power-Proportional Data Centers - Lin, Minghong; Wierman, Adam; Andrew, Lachlan L. H.; Thereska, Eno
Power consumption imposes a significant cost for data centers implementing cloud services, yet much of that power is used to maintain excess service capacity during periods of low load. This paper investigates how much can be saved by dynamically “right-sizing” the data center by turning off servers during such periods and how to achieve that saving via an online algorithm. We propose a very general model and prove that the optimal offline algorithm for dynamic right-sizing has a simple structure when viewed in reverse time, and this structure is exploited to develop a new “lazy” online algorithm, which is proven...
Determination of Fe^(3+) and Fe^(2+) Concentrations in Feldspar by Optical Absorption and EPR Spectroscopy - Hofmeister, Anne M.; Rossman, George R.
Ferrous and ferric iron concentrations in feldspars with low total iron content (<0.32 wt% total Fe) were determined from optical and electron paramagnetic resonance (EPR) spectra to better than ±15 percent of the amount present. Optical spectra indicate that Fe^(2+) occupies two distorted M-sites in plagioclases of intermediate structural state. The linear dependence of the Fe^(2+)/Fe total ratio on An content demonstrates that Fe^(2+) substitutes for Ca (not Na) so that the number of Ca-sites is a principal factor in iron partitioning in plagioclase. EPR powder spectra show that the number of sites for Fe^(3+) depends on structural state rather...
Spectroscopic Standard for Tetrahedrally Coordinated
Ferric Iron: γ LiAIO_2:Fe^(3+) - Waychunas, Glenn A.; Rossman, George R.
γ LiAlO_2 doped with Fe^(3+) in the tetrahedral site has been examined by extended X-ray absorption fine structure (EXAFS) analysis, and Mössbauer and optical spectroscopy. The isomer shift (IS) is −0.026 mm/s (Fe-Pd); the quadrupole splitting (QS) is 0.62 mm/s. Anisotropic optical absorption is prominent at ∼391, 452, and 463 nm. The K-edge absorption spectrum shows a prominent absorption near 7,113 ev typical of tetrahedrally coordinated Fe^(3+).
Co-ordination of boron in sillimanite - Grew, Edward S.; Rossman, George R.
Ion-Microprobe analyses of six sillimanites
associated with kornerupine show that the sillimanite
can incorporate from 0.035 to 0.43 wt. %
B_2O_3 (Grew and Hinthorne, 1983). Boron appears
to substitute for silicon concomitantly with Mg
substitution for Al such that the atomic Mg/B ratio
is close to 0.5. This substitution results in a
deficiency of cationic charge, which Grew and
Hinthorne (1983) attributed to a submicroscopic
rearrangement of the sillimanite structure involving
loss of oxygen. A possible substitution scheme is
2(B + xMg) → 2(Si + xAl) + (1 + x)O, where x ≃ 0.5.
In the present study, we have addressed the question
of co-ordination of boron in sillimanite. As
boron can occur in...
Radioactive Irradiated Spodumene - Rossman, George R.; Qiu, Yuanxun
During routine testing, a parcel of spodumene imported from Brazil was found to be radioactive. Detailed analysis showed that individual stones had levels of gamma ray emission far above those acceptable for jewelry purposes. Gamma ray spectroscopy revealed that they had been irradiated with neutrons. The colors of these stones are similar to those observed in citrine and have no counterpart in untreated spodumene. They range from brownish orange through orange to orange-yellow and greenish yellow.
Orientation and Motion of Water Molecules in Cordierite:
A Proton Nuclear Magnetic Resonance Study - Carson, Douglas G.; Rossman, George R.; Vaughan, Robert W.
Conventional and solid state proton nuclear magnetic resonance (NMR) techniques have been used to examine water molecules in the channels of a single crystal of cordierite, (Mg, Fe)_2Al_4Si_5O_(18), as a function of temperature, magnetic field, and orientation. Only one type of water was found rather than water in two distinct rigid orientations which were indicated by earlier infrared spectral studies. However, the measured dipolar splittings indicate that this water is in rapid motion. Shifts in the dipolar doublet due to Fe^(2+) impurities indicate that the water molecules are not moving among adjacent channel sites along a channel cavity. A two-site...