18,932 research outputs found
Erratum: Noninvasive Measurements and FEM Analyses for Estimating the Rotor Bar-Lamination Contact Resistance (IEEE Trans. Ind. Appl. (2021) 57: 1 (208-217) DOI: 10.1109/tia.2020.3028347)
No full textIn [1], the correct author affiliations should read: Z. Gmyrek is with the Institute of Mechatronics and Information Systems, Lodz University of Technology, Lodz 90-924, Poland (e-mail: [email protected]). S. Vaschetto, M. Ahmadi Darmani, and A. Cavagnino are with the Politecnico di Torino, Dipartimento Energia, Turin 10129, Italy (e-mail: [email protected]; [email protected]; andrea. [email protected])
Lyman break galaxies and the star formation rate of the Universe at z ~ 6
No full textWe determine the space density of UV-luminous starburst galaxies at z≈ 6 using deep HST ACS SDSS-i′ (F775W) and SDSS-z′ (F850LP) and VLT ISAAC J and Ks band imaging of the Chandra Deep Field South. We find eight galaxies and one star with (i′−z′) > 1.5 to a depth of z′AB= 25.6 (an 8σ detection in each of the 3 available ACS epochs). This corresponds to an unobscured star formation rate of ≈15 h−270 M⊙ yr−1 at z= 5.9, equivalent to L* for the Lyman-break population at z= 3–4 (ΩΛ= 0.7, ΩM= 0.3). We are sensitive to star-forming galaxies at 5.6 ≲z≲ 7.0 with an effective comoving volume of ≈1.8 × 105h−370 Mpc3 after accounting for incompleteness at the higher redshifts due to luminosity bias. This volume should encompass the primeval subgalactic-scale fragments of the progenitors of about a thousand L* galaxies at the current epoch. We determine a volume-averaged global star formation rate of (6.7 ± 2.7) × 10−4h70 M⊙ yr−1 Mpc−3 at z∼ 6 from rest-frame UV selected starbursts at the bright end of the luminosity function: this is a lower limit because of dust obscuration and galaxies below our sensitivity limit. This measurement shows that at z∼ 6 the star formation density at the bright end is a factor of ∼6 times less than that determined by Steidel et al. for a comparable sample of UV-selected galaxies at z= 3–4, and so extends our knowledge of the star formation history of the Universe to earlier times than previous work and into the epoch where reionization may have occurred
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Triangular Constellations in Flows
No full textParticles advected on the surface of a fluid can exhibit fractal clustering. The local structure of a fractal set is described by its dimension , which is the exponent of a power-law relating the mass in a ball to its radius : . It is desirable to characterise the {\em shapes} of constellations of points sampling a fractal measure, as well as their masses. The simplest example is the distribution of shapes of triangles formed by triplets of points, which we investigate for fractals generated by chaotic dynamical systems. The most significant parameter describing the triangle shape is the ratio of its area to the radius of gyration squared. We show that the probability density of has a phase transition: is independent of and approximately uniform below a critical flow compressibility , which we estimate. For the distribution appears to be described by two power laws: when , and when
Self-archiving practice and the influence of publisher policies in the social sciences
No full textAuthors in different disciplines exhibit very different behaviours on the so-called ‘green’ road to open access, i.e. self-archiving. This study looks at the self-archiving behaviour of authors publishing in leading journals in six social science disciplines. It tests the hypothesis that authors are self-archiving according to the norms of their respective disciplines rather than following self-archiving policies of publishers, and that, as a result, they are self-archiving significant numbers of publisher PDF versions. It finds significant levels of
self-archiving, as well as significant self-archiving of
the publisher PDF version, in all the disciplines
investigated. Publishers’ self-archiving policies have
no influence on author self-archiving practice
Large eddy simulations of weakly heated stratocumulus top boudary layer
No full textPerforming Large Eddy Simulations (LES) of marine stratocumulus in the weakly heated boundary layer is an opportunity to evaluate the relative importance of radiative cooling and of a wind shear in cloud top region on cloud structure. It is shown that cooling due to longwave radiation influences the convective circulation in the atmospheric boundary layer and counteracts dilution caused by the wind shear
Analysis of sesquiterpene pyridine alkaloids using ESI-MS/MS: The product ion at m/z 310 formed by an ion-dipole intermediate
No full textSesquiterpene pyridine alkaloids are a large group of highly oxygenated sesquiterpenoids, attracting attention in the fields of medicine because of their significant biological activities. Three representative sesquiterpene pyridine alkaloids were analyzed by electrospray ionization collision-induced dissociation-tandem mass spectrometry (ESI-CID-MS/MS/MS). In the high mass range, the product ions were formed by the loss of side chains or H2O. In the low mass range, the high-abundance product ions at m/z 206 and 178 were the characteristic ions of the pyridine moiety. Interestingly, the characteristic product ion at m/z 310 was formed through an ion-dipole (ion-neutral) complex. Addition of oxo(phenyl)methylium formed by the loss of the side chain linked to C1 and pyridine moiety produces m/z 310. The product ions at m/z 188 and 105 from m/z 310 support the proposed processes. The product ions were supported by D-labeling experiment. It was found that the formation of the product ion at m/z 310 was related to the position of substituted groups. (C) 2014 Elsevier B.V. All rights reserved
Testing the evolutionary link between submillimetre galaxies and quasars: CO observations of QSOs at z~2
No full textWe have used the IRAM Plateau de Bure millimetre interferometer and the UKIRT 1–5 μm Imager Spectrometer (UIST) to test the connection between the major phases of spheroid growth and nuclear accretion by mapping CO emission in nine submillimetre-detected QSOs at z= 1.7–2.6 with black hole (BH) masses derived from near-infrared spectroscopy. When combined with one QSO obtained from the literature, we present sensitive CO(3–2) or CO(2–1) observations of 10 submillimetre-detected QSOs selected at the epoch of peak activity in both QSOs and submillimetre (submm) galaxies (SMGs). CO is detected in 5/6 very optically luminous (MB∼−28) submm-detected QSOs with BH masses MBH≃ 109–1010 M⊙, confirming the presence of large gas reservoirs of Mgas≃ 3.4 × 1010 M⊙. Our BH masses and dynamical mass constraints on the host spheroids suggest, at face value, that these optically luminous QSOs at z= 2 lie about an order of magnitude above the local BH–spheroid relation, MBH/Msph, although this result is dependent on the size and inclination of the CO-emitting region. However, we find that their BH masses are ∼30 times too large and their surface density is ∼300 times too small to be related to typical SMGs in an evolutionary sequence. Conversely, we measure weaker CO emission in four fainter (MB∼−25) submm-detected QSOs with properties, BH masses (MBH≃ 5 × 108 M⊙), and surface densities similar to SMGs. These QSOs appear to lie near the local MBH/Msph relation, making them plausible ‘transition objects’ in the proposed evolutionary sequence linking QSOs to the formation of massive young galaxies and BHs at high redshift. We show that SMGs have a higher incidence of bimodal CO line profiles than seen in our QSO sample, which we interpret as an effect of their relative inclinations, with the QSOs seen more face-on. Finally, we find that the gas masses of the four fainter submm-detected QSOs imply that their star formation episodes could be sustained for ∼10 Myr, and are consistent with representing a phase in the formation of massive galaxies which overlaps a preceding SMG starburst phase, before subsequently evolving into a population of present-day massive ellipticals
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