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This book provides an illuminating account of teachers' own reflections on their experiences of teaching in urban schools. It was conceived as a direct response to policy-related and media-generated concerns about male teacher shortage and offers a critique of the call for more male role models in elementary schools to address important issues regarding gender, race and the politics of representation. By including the perspectives of minority teachers and students, and by drawing on feminist, queer and anti-racist frameworks, this book rejects the familiar tendency to resort to role modelling as a basis for explaining or addressing boys' disaffection with schooling. Indeed, the authors argue, on the basis of their research in urban schools in Canada and Australia, that educational policy concerned with male teacher shortage and the plight of disadvantaged minority boys would benefit from engaging with analytic perspectives and empirical literature that takes readers beyond hegemonic discourses of role modelling. A compelling case is presented for the need to disarticulate discourses about role modelling from a politics of representation that is committed to addressing the reality of the impact of racial and structural inequalities on both minority teachers and students' participation in the education system. The book also provides insight into the persistence of gender inequality as it relates to the status of elementary school teaching as women's work.

Copyright of Ecografia Dell-Apparato Osteoarticolare is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecografia Dell-Apparato Osteoarticolare is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecografia Dell-Apparato Osteoarticolare is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecografia Dell-Apparato Osteoarticolare is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecografia Dell-Apparato Osteoarticolare is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecografia Dell-Apparato Osteoarticolare is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Interferometers operating with high spectral resolution at visible and infrared wavelengths can provide information in spectral lines and velocity-resolved data on the milliarcsecond and sub-millisecond scale. This enables completely new observational approaches to many open problems regarding the physics of stars and circumstellar matter. Using fibers to couple the output from a relatively simple beam combiner to existing spectrographs offers a fast and cost-effective way to implement interferometric high-resolution spectroscopy. [ABSTRACT FROM AUTHOR]

CRIRES, a pre-dispersed CRyogenic Infrared Echelle Spectrograph, provides a resolving power λ / Δ λ ≈ 105, (or Δ v ≈ 1.5 kms, per pixel) between 1000 and 5000 nm, at the 8m ESO VLT-UT 1. A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide 0.2" spatial resolution along the slit. A mosaic of 4 Aladdin InSb-arrays packaged on custom-fabricated ceramics boards provides for an effective 5k x 0.5k pixel focal plane array. Remote insertion of gas cells to measure high precision radial velocities is possible. A linear and circular polarization mode for magnetic Doppler imaging of stellar surfaces is foreseen with motorized retarders in combination with a Wollaston prism. The major design features of CRIRES and a glimpse tutorial preview of astronomical data are given. [ABSTRACT FROM AUTHOR]

The technique of absolute velocimetry has been applied to the backscattered solar spectrum of Titan in order to measure the Doppler shift associated with the zonal circulation in the equatorial region. Eastward winds were measured, with lower limits of 62 and 50 ms-1, at altitudes near 200 and 170 km, and significant statistical evidence was observed for stronger winds at the higher altitudes. The same technique was applied in January 2005 as part of an international effort in support of the European Space Agency's Huygens Probe mission and led to wind speed values quite consistent with our previous results. [ABSTRACT FROM AUTHOR]

Gaseous and dusty circumstellar disks are commonly thought to be the birth place of planetary systems. Once planets are formed, the so-called "debris disks" are still active complex evolving systems in which gas and dust are interacting and replenishing. This was notably demonstrated through visible and UV absorption spectroscopy of the most famous debris disk around the main sequence star β Pictoris. Hourly variable absorbing components are explained by a multitude of sublimating comets when grazing the star. This intense cometary activity is the proposed source for the gas and one possible origin for the replenishment of the dust. Hundreds of cometary-like events are observed, from different comet families. [ABSTRACT FROM AUTHOR]

Here we show how to determine the orbital parameters of a system composed of a star and N, companions (that can be planets, brown-dwarfs or other stars), using a simple Fourier analysis of the radial velocity data of the star. This method supposes that all objects in the system follow keplerian orbits around the star and gives better results for a large number of observational points. The orbital parameters may present some errors, but they are an excellent starting point for the traditional minimization methods such as the Levenberg-Marquardt algorithms. [ABSTRACT FROM AUTHOR]

We present the results of radial velocity measurements of two samples of active stars. The first sample contains field G and K giants across the Red Giant Branch, whereas the second sample consists of nearby young stars (d<, 150 pc) with ages between 10 and 300 Myrs. The radial velocity monitoring program has been carried out with FEROS at 1.52 m ESO telescope (1999 - 2002) and continued since 2003 at 2.2 m MPG/ESO telescope. We observed stellar radial velocity variations which originate either from the stellar activity or the presence of stellar/substellar companions. By means of a bisector technique we are able to distinguish the sources of the radial velocity variation. Among them we found few candidates of planetary companions, both of young stars and G-K giants sample. [ABSTRACT FROM AUTHOR]

The dependence of planetary statistics on the physical conditions during the initial stages of the system (i.e. in the proto-planetary disk) represent an essential constraint on planetary formation mechanisms. The planets orbiting M dwarfs were formed in a lower-mass disk, with an ice boundary much closer to the star, and a longer orbital period (for the same separation) than the planets formed around solar-type stars. Planetary formation is extremely sensitive to all three parameters, and the relative statistical properties of planets around G dwarfs and very low mass stars therefore represent a very sensitive diagnostic. In this talk we will present the first results of a very sensitive search for planets around southern M dwarfs with the HARPS spectrograph (as part of the HARPS GTO program). The northern counterpart of the survey will be conducted with SOPHIE at OHP, within the SOPHIE Exoplanets Consortium. These first results suggest that that planets around M dwarfs have lower mass than around solar type stars. [ABSTRACT FROM AUTHOR]

The identification of transiting planets candidates and their a posteriori confirmation and characterization by means of spectroscopic follow-up is allowing us to study the internal physics of these planets. Here we briefly discuss the spectroscopic follow-up of the OGLE transiting candidates carried out at the ESO/VLT. [ABSTRACT FROM AUTHOR]

We present results from the first three years of operations of the HARPS spectrograph installed on the ESO-3.6m telescope at La Silla Observatory, Chile. This instrument, primarily built to detect extrasolar planetary systems, has demonstrated a long-term accuracy below the 1 m s-1, level, exploring a new regime in RV precision and discovering several very low-mass planets. We present recent improvements in the wavelength calibration process, including the creation of a new ThAr reference atlas and the use of a much larger number of lines to fit the wavelength solution. Other instrumental error sources such as guiding accuracy and photon noise are discussed and a global error budget is presented. Finally, ongoing studies to obtain an "ideal" wavelength calibration are briefly reviewed. [ABSTRACT FROM AUTHOR]

The use of a gas absorption cell as the velocity metric has become a standard method of achieving the very high velocity precision necessary for detection of low-mass planetary companions to nearby stars. At present, I2, is the most commonly used gas. This gas absorption cell technique has a number of significant advantages: 1) The I2, spectrum is an absorption spectrum superimposed directly on the stellar spectrum. Thus, the reference spectrum follows exactly the same illumination pattern as the stellar spectrum. 2) The extremely narrow I2, absorption lines permit modeling of small-scale variations in the spectrograph instrumental profile. 3) It is easy and inexpensive to retrofit an existing spectrograph with an I2, cell. The I2, cell technique has been exceptionally successful in the detection of extra-solar planets. [ABSTRACT FROM AUTHOR]

We determined [Fe/H] for 17 double-mode Cepheids of the southern hemisphere using high-resolution echelle spectra. For five of the program stars these are the first iron abundances in the literature. The available data suggest that the period ratio for galactic beat Cepheids is mainly determined by their metallicity. Therefore, the observed period ratios do not reflect large differences in their mass, effective temperature or luminosity. [ABSTRACT FROM AUTHOR]

Type II Cepheids populate the same region of the instability strip as Classical Cepheids, but they belong to older stellar population. Their different stellar structure may result in different pulsational characteristics. We study the relative motion of the photospheric and chromospheric layers of Type II Cepheids by comparing radial velocities of metal lines and Hα. It is shown that in the P = 1 - 3, days regime the two types are markedly different, but their atmospheric motions become quite similar at longer periods. [ABSTRACT FROM AUTHOR]

We review methodologies currently available to interprete time series of high-resolution high-S/N spectroscopic data of pulsating stars in terms of the kind of (non-radial) modes that are excited. We illustrate the drastic improvement of the detection treshold of line-profile variability thanks to the advancement of the instrumentation over the past two decades. This has led to the opportunity to interprete line-profile variations with amplitudes of order m/s, which is a factor 1000 lower than the earliest line-profile time series studies allowed for. [ABSTRACT FROM AUTHOR]

High-precision radial-velocity techniques, which enabled the detection of extrasolar planets, are now sensitive to relativistic effects in the data of spectroscopic binary stars (SBs). These effects can be used to derive the absolute masses of the components of eclipsing single-lined SBs and double-lined SBs from Doppler measurements alone. High-precision stellar spectroscopy can thus substantially increase the number of measured stellar masses, thereby improving the mass-radius and mass-magnitude calibrations. [ABSTRACT FROM AUTHOR]

We propose a new method for determination of element abundances in stellar atmospheres aimed for the automatic processing of high-quality stellar spectra. The pan-spectral method is based on weighted cumulative line-widths Qλ=∫λλ0∣dRλdZ∣(1-Rλ)dλ, where Rλ, is residual flux and Z, is abundance of studied element. Difference in quantities Qλ, found from synthetic and observed spectra gives a correction to the initial abundance. Final abundances are then found by rapidly converging iterations. Calculations can be made for many elements simultaneously and do not demand supercomputers. [ABSTRACT FROM AUTHOR]

Spectral-line displacements away from the wavelengths naively expected from the Doppler shift due to radial motion may originate as convective shifts (correlated velocity and brightness patterns), as gravitational redshifts, or be induced by wave motions. Convective shifts are important tools for testing 3-dimensional stellar hydrodynamics; analogous shifts may be expected even in intergalactic absorption lines (convection driven by AGNs in clusters of galaxies). [ABSTRACT FROM AUTHOR]

We describe the joint efforts by the European Southern Observatory (ESO), the Space Telescope European Co-ordinating Facility (ST-ECF), and the United States National Institute of Standards and Technology (NIST) to establish the Th-Ar hollow cathode lamp as a standard for the calibration of VLT (Very Large Telescope) spectrographs in the near infrared (IR). In the near IR only a limited number of wavelength standards are available. Th-Ar hollow cathode lamps provide a rich spectrum in the ultraviolet (UV)-visible region and have been used in astronomy for a long time. We report new measurements using the 2-m UV/visible/IR Fourier transform spectrometer (FTS) at NIST that establish more than 2000 lines as wavelength standards in the range 900 nm to 4500 nm. This line list is used as input for a physical model that provides the wavelength calibration for the Cryogenic High-Resolution IR Echelle Spectrometer (CRIRES), ESO's new high-resolution (R≈100 000) IR spectrograph at the VLT. Based on these data and additional measurements investigating other properties relevant for operations we conclude that Th-Ar lamps hold the promise of becoming a standard source for wavelength calibration in near IR astronomy. [ABSTRACT FROM AUTHOR]

Many theories of dark energy invoke rolling scaler fields which in turn predict time variable fundamental constants such as the ratio of electron to proton mass μ. Molecular energy levels are sensitive to μ, with the electronic, vibrational and rotational levels affected each in a different manner depending on their quantum numbers. High redshift damped Lyman alpha clouds with molecular hydrogen offer an excellent opportunity to search for this possible variation. New, very accurate, laboratory measurements of the wavelengths of the Lyman and Werner transitions make it now possible to check whether the small variations in wavelength due to a time varying value of μ, are present. [ABSTRACT FROM AUTHOR]

Radio spectroscopy in the four redshifted 18cm OH lines allows a probe of changes in three fundamental constants, the fine structure constant α, the proton g-factor gp, and the electron-proton mass ratio $μ ≡ me/mp. After summarizing the technique, we describe WSRT observations of the conjugate satellite OH lines towards PKS 1413+135, which find weak evidence in support of evolution in the constants, over a lookback time of ∼ 2.7, Gyrs. [ABSTRACT FROM AUTHOR]

Precise radial velocity measurements (δ v/c ∼ 10-7) of Fe II lines in damped Lyα systems from very high quality VLT/UVES spectra of quasars HE 0515-4414 and Q 1101-264 are used to probe cosmological time dependence of the fine structure constant, α.It is found that between two redshifts z1 = 1.15, and z2 = 1.84, the value of Δ α/α changes at the level of a few ppm: (αz2 - αz1)/α0 = 5.43±2.52, ppm. Variations of α can be considered as one of the most reliable method to constrain the dark energy equation of state and improvements on the accuracy of the wavelength calibration of QSO spectra are of great importance. [ABSTRACT FROM AUTHOR]

We summarize the constraints on a possible time variation of the fine-structure constant, α, we obtained using UVES/VLT data. In particular, we report new results based on the analysis of 6 Ni II systems. No variation is found to a fractional level of about 0.2X10-5, over a redshift range 0.4≤ z≤ 2.5. We discuss the importance of precision spectroscopy to improve the constraint on α, variation, based on our detailed analysis of a high resolution spectrum (R~ 112 000) obtained with HARPS. [ABSTRACT FROM AUTHOR]

Current analyses of VLT/UVES quasar spectra disagree with the Keck/HIRES evidence for a varying fine-structure constant, α. To investigate this we introduce a simple method for calculating the minimum possible uncertainty on Δα/α for a given quasar absorber. For many absorbers in Chand et al. (2004) and for the single-absorber constraint of Levshakov et al. (2006) the quoted uncertainties are smaller than the minimum allowed by the UVES data. Failure of this basic consistency test prevents reliable comparison of the UVES and HIRES results. [ABSTRACT FROM AUTHOR]