17,066 research outputs found
Spitzer Imaging of Herschel-ATLAS Gravitationally Lensed Submillimeter Sources
We present physical properties of two submillimeter selected gravitationally lensed sources, identified in the
Herschel Astrophysical Terahertz Large Area Survey. These submillimeter galaxies (SMGs) have flux densities
>100 mJy at 500 μm, but are not visible in existing optical imaging. We fit light profiles to each component of
the lensing systems in Spitzer IRAC 3.6 and 4.5 μm data and successfully disentangle the foreground lens from
the background source in each case, providing important constraints on the spectral energy distributions (SEDs)
of the background SMG at rest-frame optical–near-infrared wavelengths. The SED fits show that these two SMGs
have high dust obscuration with A_V ~ 4–5 and star formation rates of ~100M_⊙ yr^(−1). They have low gas fractions
and low dynamical masses compared with 850 μm selected galaxies
The case for the multi-species ecological system, with special reference to succession and stability
Multi-species life support system based on ecological theor
Case study of a female ocean racer: prerace preparation and nutritional intake during the Vendee Globe 2008.
The Vendée Globe is a solo round-the-world sailing race without stopovers or assistance, a physically demanding challenge for which appropriate nutrition should maintain energy balance and ensure optimum performance. This is an account of prerace nutritional preparation with a professional and experienced female racer and assessment of daily nutritional intake (NI) during the race using a multimethod approach. A daily energy intake (EI) of 15.1 MJ/day was recommended for the race and negotiated down by the racer to 12.7 MJ/day, with carbohydrate and fluid intake goals of 480 g/day and 3,020 ml/day, respectively. Throughout the 99-day voyage, daily NI was recorded using electronic food diaries and inventories piloted during training races. NI was assessed and a postrace interview and questionnaire were used to evaluate the intervention. Fat mass (FM) and fat-free mass (FFM) were assessed pre- (37 days) and postrace (11 days) using dual-energy X-ray absorptiometry, and body mass was measured before the racer stepped on the yacht and immediately postrace. Mean EI was 9.2 MJ/day (2.4-14.3 MJ/day), representing a negative energy balance of 3.5 MJ/day under the negotiated EI goal, evidenced by a 7.9-kg loss of body mass (FM -7.5 kg, FFM -0.4 kg) during the voyage, with consequent underconsumption of carbohydrate by ~130 g/day. According to the postrace yacht food inventory, self-reported EI was underreported by 7%. This intervention demonstrates the practicality of the NI approach and assessment, but the racer's nutrition strategy can be further improved to facilitate meeting more optimal NI goals for performance and health. It also shows that evaluation of NI is possible in this environment over prolonged periods, which can provide important information for optimizing nutritional strategies for ocean racing
The development and application of aerodynamic uncertainties: And flight test verification for the space shuttle orbiter
The approach used in establishing the predicted aerodynamic uncertainties and the process used in applying these uncertainties during the design of the Orbiter flight control system and the entry trajectories are presented. The flight test program that was designed to verify the stability and control derivatives with a minimum of test flights is presented and a comparison of preflight predictions with preliminary flight test results is made. It is concluded that the approach used for the Orbiter is applicable to future programs where testing is limited due to time constraints or funding
Three-dimensional calculation of shuttle charging in polar orbit
The charged particles environment in polar orbit can be of sufficient intensity to cause spacecraft charging. In order to gain a quantitative understanding of such effects, the Air Force is developing POLAR, a computer code which simulates in three dimensions the electrical interaction of large space vehicles with the polar ionospheric plasma. It models the physical processes of wake generation, ambient ion collection, precipitating auroral electron fluxes, and surface interactions, including secondary electron generation and backscattering, which lead to vehicle charging. These processes may be followed dynamically on a subsecond timescale so that the rapid passage through intense auroral arcs can be simulated. POLAR models the ambient plasma as isotropic Maxwellian electrons and ions (0+, H+), and allows for simultaneous precipitation of power-law, energetic Maxwellian, and accelerated Gaussian distributions of electrons. Magnetic field effects will be modeled in POLAR but are currently ignored
Gyrotron experiments employing a field emission array cathode
The design and operation of a field emission array (FEA) cathode and the subsequent demonstration of the first FEA gyrotron are presented. Up to 10 mA from 30 000 tips was achieved reproducibly from each of ten chips in a gyrotron environment, namely, a vacuum 1 x 10(-8) mbar, -50 kV potential with multiple chip operation, The design parameters of the FEA gun were similar to those of a magnetron injection gun with an achievable electron beam current of 50-100 mA and measured power 720 W cw. Coherent microwave radiation was detected in both TE(02) at 30.1 GHz and TE(03) at 43.6 GHz, with a starting current of 1 mA
A geometric proof of the Kochen-Specker no-go theorem
We give a short geometric proof of the Kochen-Specker no-go theorem for
non-contextual hidden variables models. Note added to this version: I
understand from Jan-Aake Larsson that the construction we give here actually
contains the original Kochen-Specker construction as well as many others (Bell,
Conway and Kochen, Schuette, perhaps also Peres).Comment: This paper appeared some years ago, before the author was aware of
quant-ph. It is relevant to recent developments concerning Kochen-Specker
theorem
SU(3) breaking in hyperon transition vector form factors
We present a calculation of the SU(3)-breaking corrections to the hyperon
transition vector form factors to in heavy baryon chiral
perturbation theory with finite-range regularisation. Both octet and decuplet
degrees of freedom are included. We formulate a chiral expansion at the
kinematic point , which can be conveniently accessed
in lattice QCD. The two unknown low-energy constants at this point are
constrained by lattice QCD simulation results for the
and transition form factors. Hence we determine
lattice-informed values of at the physical point. This work constitutes
progress towards the precise determination of from hyperon
semileptonic decays
The economic and innovation contribution of universities: a regional perspective
Universities and other higher education institutions (HEIs) have come to be regarded as key sources of knowledge utilisable in the pursuit of economic growth. Although there have been numerous studies assessing the economic and innovation impact of HEIs, there has been little systematic analysis of differences in the relative contribution of HEIs across regions. This paper provides an exploration of some of these differences in the context of the UK’s regions. Significant differences are found in the wealth generated by universities according to regional location and type of institution. Universities in more competitive regions are generally more productive than those located in less competitive regions. Also, traditional universities are generally more productive than their newer counterparts, with university productivity positively related to knowledge commercialisation capabilities. Weaker regions tend to be more dependent on their universities for income and innovation, but often these universities under-perform in comparison to counterpart institutions in more competitive regions. It is argued that uncompetitive regions lack the additional knowledge infrastructure, besides universities, that are more commonly a feature of more competitive regions
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