A near-infrared morphological comparison of high-redshift submm and radio galaxies: massive star-forming discs vs relaxed spheroids

We present deep, high-quality K-band images of complete subsamples of powerful radio and sub-mm galaxies at z=2. The data were obtained in the best available seeing at UKIRT and Gemini North, with integration times scaled to ensure that comparable rest-frame surface brightness levels are reached for all galaxies. We fit two-dimensional axi-symmetric galaxy models to determine galaxy morphologies at rest-frame optical wavelengths > 4000A, varying luminosity, axial ratio, half-light radius, and Sersic index. We find that, while some images show evidence of galaxy interactions, >95% of the rest-frame optical light in all galaxies is well-described by these simple models. We also find a clear difference in morphology between these two classes of galaxy; fits to the individual images and image stacks reveal that the radio galaxies are moderately large (=8.4+-1.1kpc; median r{1/2}=7.8), de Vaucouleurs spheroids ( = 4.07+-0.27; median n=3.87), while the sub-mm galaxies appear to be moderately compact (=3.4+-0.3kpc; median r{1/2}=3.1kpc) exponential discs (=1.44+-0.16; median n=1.08). We show that the z=2 radio galaxies display a well-defined Kormendy relation but that, while larger than other recently-studied high-z massive galaxy populations, they are still ~1.5 times smaller than their local counterparts. The scalelengths of the starlight in the sub-mm galaxies are comparable to those reported for the molecular gas. Their sizes are also similar to those of comparably massive quiescent galaxies at z>1.5. In terms of stellar mass surface density, the majority of the radio galaxies lie within the locus defined by local ellipticals. In contrast, while best modelled as discs, most of the sub-mm galaxies have higher stellar mass densities than local galaxies, and appear destined to evolve into present-day massive ellipticals.Comment: 24 pages, 9 figure

An Ultrasonic Sensor for Distance Measurement in Automotive Applications

This paper describes an ultrasonic sensor that is able to measure the distance from the ground of selected points of a motor vehicle. The sensor is based on the measurement of the time of flight of an ultrasonic pulse, which is reflected by the ground. A constrained optimization technique is employed to obtain reflected pulses that are easily detectable by means of a threshold comparator. Such a technique, which takes the frequency response of the ultrasonic transducers into account, allows a sub-wavelength detection to be obtained. Experimental tests, performed with a 40 kHz piezoelectric-transducer based sensor, showed a standard uncertainty of 1 mm at rest or at low speeds; the sensor still works at speeds of up to 30 m/s, although at higher uncertainty. The sensor is composed of only low cost components, thus being apt for first car equipment in many cases, and is able to self-adapt to different conditions in order to give the best result

There\u27s A Million Heroes in Each Corner of the U.S.A

[Verse 1] Virginia gave us Washington, way back in Sev’nty six Kentucky gave us Lincoln when our boys were in a fix Ohio gave us Grant and Dixie gave us Lee They fought it out and patched it up and made our history If you asked Uncle Sammy who could take their place today He’d rub his chin and with a grin he’d answer in this way. [Chorus] There’s a million heroes in each corner of the U.S.A. In cities and farms They’ve taken up arms The East and West have sent their best the rest are coming from the land of cotton You can bank on ev’ry loyal Yank to fight till the end of the fray When danger threatens they all rally ‘round That’s why the flag has never touched the ground There’s a million heroes in each corner of the U.S.A. [Verse 2] Columbus found America the home of peace and rest And Betsy Ross she found a flag to stand each battle test Tho’ heroes of the past have laid away the gun Their spirits live within the hearts of ev’ry native son Our flag is just as clean today as when it first was made each stripe and star a battle scar and still I’m not afraid. [Chorus

Revisiting the Best of the Best: Innovations in the Hotel Practice

[Excerpt] To what extent will current industry best practices stand the rest of time? Will existing excellent practices become integral to the organization or become obsolete and be discarded? The answers to these critical questions rest on the process of continuous reassessment and renewal that is a feature of organizational learning. Organizational learning often begins with an individual champion who recognizes a gap between what is and what could be, engages in a process of discovery and data gathering, and then develops an idea – often in the form of a new practice – to produce a change in the organization.1 The question we discuss in this paper is how well best practices persist. Specifically, we discuss whether the best practices chronicled in a comprehensive study of the U.S. lodging industry five years ago are still being used and the extent to which they have been refined or modified over the years.2 The original best-practices study constituted a compilation of what industry practitioners and customers considered to be the most effective strategies and techniques used at the end of the twentieth century by the lodging industry’s best operators to create excellence for all stakeholders

The Rest-Frame Optical Properties of z~3 Galaxies

We present the results of a near-infrared imaging survey of z~3 Lyman Break Galaxies (LBGs). The survey covers a total of 30 arcmin^2 and includes 118 photometrically selected LBGs with K_s band measurements, 63 of which also have J band measurements, and 81 of which have spectroscopic redshifts. Using the distribution of optical {\cal R} magnitudes from previous work and {\cal R}-K_s colors for this sub-sample, we compute the rest-frame optical luminosity function of LBGs. At the brightest magnitudes, where it is fairly well constrained, this luminosity function strikingly exceeds locally determined optical luminosity functions. The V-band luminosity density of only the observed bright end of the z~3 LBG luminosity function already approaches that of all stars in the local universe. For the 81 galaxies with measured redshifts, we investigate the range of LBG stellar populations implied by the photometry which generally spans the range 900--5500 AA in the rest-frame. While there are only weak constraints on the parameters for most of the individual galaxies, there are strong trends in the sample as a whole. A unified scenario which accounts for the observed trends in bright LBGs is one in which a relatively short period of very rapid star-formation (hundreds of M_sun/yr) lasts for roughly 50--100 Myr, after which both the extinction and star-formation rate are considerably reduced and stars are formed at a more quiescent, but still rapid, rate for at least a few hundred Myr. In our sample, a considerable fraction (~20%) of the LBGs have best-fit star-formation ages ~> 1 Gyr, implied stellar masses of ~> 10^10 M_sun, and are still forming stars at \~30 M_sun/yr.Comment: 61 pages including 19 figures. Accepted for publication in Ap

Endogenous Differential Mortality, Non-Contractible Effort and Non Linear Taxation

This paper studies a problem of non linear taxation when individuals have different longevities resulting from a non-monetary effort (like exercising). We first present the laissez-faire and the first best. Like Becker and Philipson (1998), we find that the laissez-faire level of effort is too high compared with the first best, because individuals do not internalize the impact of survival on the return of their savings. We also claim that because of its non-monetary form, effort is not contractible. That is why we modify our framework and assume, for the rest of the paper, that effort is determined by the individual while the social planner only allocates consumptions. It turns out that, under full information, a tax on the return of annuitized savings is desirable for both types. This tax is higher for the low-survival individual. Under asymmetric information, the low-survival individual still faces a tax while the high-survival individual might now face a positive or negative tax on annuities. Interestingly, our results depend on the value of life.annuities, effort, differential mortality, non linear taxation, value of life

Ionized Nitrogen Mono-hydride Bands are Identified in the Pre-solar and Carbonado Diamond Spectra

None of the well established Nitrogen related IR absorption bands, common in synthetic and terrestrial diamonds, have been identified in the pre-solar diamond spectra. In the carbonado diamond spectra only the single nitrogen impurity (C centre) is identified and the assignments of the rest of the nitrogen-related bands are still debated. It is speculated that the unidentified bands in the Nitrogen absorption region are not induced by Nitrogen but rather by Nitrogen-hydrides because in the interstellar environment Nitrogen reacts with Hydrogen and forms NH+; NH; NH2; NH3. Among these Hydrides the electronic configuration of NH+ is the closest to Carbon. Thus this ionized Nitrogen-mono-hydride is the best candidate to substitute Carbon in the diamond structure. The bands of the substitutional NH+ defect are deduced by red shifting the irradiation induced N+ bands due to the mass of the additional Hydrogen. The six bands of the NH+ defects are identified in both the pre-solar and the carbonado diamond spectra. The new assignments identify all of the nitrogen-related bands in the spectra, indicating that pre-solar and carbonado diamonds contain only single nitrogen impurities

Legitimate Peripheral Participation: Entering A Community of Practice

Etienne Wenger and Jean Lave were authors critiquing educational assumptions that are largely still with us in public education, namely that learning is an individual process, that is has a beginning and an end, that is is best separated from the rest of our activities, and that it is the result of teaching. This article will introduce and explore the social theory of learning, identify key concepts and illustrate them with specific examples, and will conclude with considerations around the promise and challenge of leveraging the power of this theory in the seminary experience