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Elliptical
Terms modified by Elliptical Selected AbstractsDemonstration of Left Ventricular Outflow Tract Eccentricity by Real Time 3D Echocardiography: Implications for the Determination of Aortic Valve AreaECHOCARDIOGRAPHY, Issue 8 2007Sanjay Doddamani M.D. Background: Determination of the left ventricular outflow tract cross-sectional area (ALVOT) is necessary for calculating aortic valve area (AVA) by echocardiography using the continuity equation (CE). In the commonly applied form of CE, ,r2 is used to estimate ALVOT utilizing the assumptions that LVOT is round and the parasternal long axis (PLAX) plane bisects LVOT. Imaging LVOT using real time 3D echocardiography (RT3DE) eliminates the need for these assumptions. We tested the hypothesis that LVOT is round based on a formula for eccentricity. Methods and Results: In 53 patients, 2D echocardiography (2DE) and RT3DE were acquired. ALVOT was calculated by 2DE using ,r2 (ALVOT-2D). Using RT3DE, ALVOT planimetry was performed immediately beneath the aortic valve (ALVOT-3Dplan). Eccentricity Index (EI) was calculated using the shortest and longest LVOT diameters. The long axis was measured to be larger by 0.53 cm ± 0.36 (P < 0.005). The median EI was 0.20 (0.00,0.54), indicating that half the subjects had at least a 20% difference between the major and minor diameters. ALVOT-3Dplan was larger than ALVOT-2D (3.73 ± 0.95 cm2 vs. 3.18 ± 0.73 cm2; P < 0.001) by paired analysis. Using the equation of an ellipse (,ab), ALVOT-3Dellip was 3.57 ± 0.95 resulting in improved agreement with ALVOT-3Dplan. Conclusions: In our small patient sample with normal aortic valves, we showed the LVOT shape is usually not round and frequently, elliptical. Incorrectly assuming a round LVOT underestimated the ALVOT-3Dplan and consequently the AVA by 15%. Investigating the LVOT in aortic stenosis is warranted to evaluate whether RT3DE may improve measurement of AVA. [source] Biology of Bactrocera (Zeugodacus) tau (Walker) (Diptera: Tephritidae)ENTOMOLOGICAL RESEARCH, Issue 5 2010Shakti Kumar SINGH Abstract The biology of the fruit fly Bactrocera tau, an important horticultural pest, was studied under laboratory conditions at 25°C and 60,70% relative humidity on Cucurbita maxima. The duration of mating averaged 408.03 ± 235.93 min. After mating, the female fly had a preoviposition period of 11.7 ± 4.49 days. The oviposition rate was 9.9 ± 8.50 eggs and fecundity was 464.6 ± 67.98 eggs/female. Eggs were elliptical, smooth and shiny white, turning darker as hatching approached, and measured 1.30 ± 0.07 mm × 0.24 ± 0.04 mm. The chorion has polygonal microsculpturing and is species-specific with polygonal walls. The egg period lasts for 1.3 ± 0.41 days. The duration of the larval period is 1.2 ± 0.42, 1.7 ± 0.48 and 4.0 ± 0.94 days for first, second and third instars, respectively. Pupation occurs in the sand or soil and pupal periods are 7.0 ± 0.47 days. The life cycle from egg to adult was completed in 14.2 ± 1.69 days; the longevity of mated females and males was 130.33 ± 14.18 and 104.66 ± 31.21 days, respectively. At least two to three generations were observed from June 2008 to June 2009. [source] A numerical solution for the equation of the lifting surface in ground effectsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2002r Drago Abstract Using the Gauss-type quadrature formulas one discretizes the 2d integral equation of the lifting surface in ground effects. Numerical calculations of the aerodynamical coefficients are performed for the elliptical and rectangular wings. Copyright 2002 John Wiley & Sons, Ltd. [source] Trefftz solutions for piezoelectricity by Lekhnitskii's formalism and boundary-collocation methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2006N. Sheng Abstract In this paper, a solution procedure for plane piezoelectricity is developed by Trefftz boundary-collocation method. Starting with the general plane piezoelectricity solution derived by Lekhnitskii's formalism, the basic sets of Trefftz functions which satisfy the homogeneous governing equations are derived. Moreover, special sets of Trefftz functions are derived for impermeable elliptical voids, impermeable sharp cracks and permeable sharp cracks with arbitrary orientations with respect to the material poling direction. The functions in the special sets satisfy not only the homogeneous governing equations but also the boundary conditions at the peripheries of the pertinent defects. By adopting Trefftz functions as the trial functions, multi-domain Trefftz boundary-collocation method is formulated. Numerical examples are presented to illustrate the efficacy of the formulation. Copyright © 2005 John Wiley & Sons, Ltd. [source] Surgical approach to benign small papular and dome-shaped melanocytic naevi on the faceJOURNAL OF COSMETIC DERMATOLOGY, Issue 3-4 2003U Tursen Summary Patients frequently request removal of benign papular and dome-shaped naevi for cosmetic or functional reasons. Melanocytic naevi can be removed by elliptical, round, punch or shave excision or destroyed using electrodessication or cryotherapy. Total elliptical excision is probably the most widely used method of removal. If malignancy is suspected, adequate specimens for histological interpretation are required. When malignancy is not suspected, the cosmetic result becomes the first priority. Smaller incisions minimize tissue trauma and so give cosmetically superior results. Round excision has been recommended for the removal of moles but has not been widely practised. Round excision and punch excision may be better alternatives than conventional fusiform excision of benign dome-shaped or papular naevi of the face, as more tissue is preserved. Shave excision of naevi may be preferable to elliptical excision in sites where the incidence of hypertrophic scarring is high, as preservation of some thickness of the dermis may result in a more acceptable scar or even avoid a scar entirely. Expedient and simple surgery with excellent cosmetic results can be accomplished by the use of punches. Cryotherapy with cutting or curetting and electrodesiccation combined with shaving have been described. Round excision may be a better alternative to conventional fusiform or shave excision of benign papular or dome-shape nevus of the face because it leaves an almost imperceptible scar. In this technique, less skin is excised and histopathological examination can be done. [source] Role of MRI in investigating the effects of elastic compression stockings on the deformation of the superficial and deep veins in the lower legJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2007Steven P. Downie MEng Abstract Purpose To evaluate the potential of MRI to investigate the mechanical effects of compression stockings on the veins of the lower limb. Materials and Methods The right calves of eight healthy volunteers were imaged in the prone position, with and without the presence of a compression stocking. Cross-sectional areas of all peroneal and posterior tibial veins, both saphenous veins, and any sufficiently large superficial veins were segmented in all subjects at mid-calf level in both cases. Variation in cross-sectional area along the axis of the great saphenous vein and a peroneal vein was also examined in three subjects. Results The mean cross-sectional area reduction was found to be greater in the deep veins (64%) than in the superficial veins (39%). Deep-vein cross-sections were generally elliptical, while superficial veins were approximately circular. Significant axial fluctuations were found in the cross-sectional areas. Conclusion MRI offers a precise source of data on the mechanical effects of lower-limb compression. Ultrasound (US) may be more cost-effective, but the data acquired are less comprehensive. Future biomechanical studies of lower-limb compression should make use of MRI. J. Magn. Reson. Imaging 2007;26:80,85. © 2007 Wiley-Liss, Inc. [source] Nanoscale uniformity of pore architecture in diatomaceous silica: a combined small and wide angle x-ray scattering studyJOURNAL OF PHYCOLOGY, Issue 1 2000Engel G. Vrieling Combined small and wide angle X-ray scattering (SAXS and WAXS) analysis was applied to purified biogenic silica of cultured diatom frustules and of natural populations sampled on marine tidal flats. The overall WAXS patterns did not reveal crystalline phases (WAXS domain between 0.07 to 0.5 nm) in this biogenic silica, which is in line with previous reports on the amorphous character of the SiO2 matrix of diatom frustules. One exception was the silica of the pennate species Cylindrotheca fusiformis Reimann et Lewin, which revealed wide peaks in the WAXS spectra. These peaks either indicate the presence of a yet unknown crystalline phase with a repetitive distance (d -value ,0.06 nm) or are caused by the ordering of the fibrous silica fragments; numerous girdle bands. The SAXS spectra revealed the size range of pores (diameter d between 3.0 and 65 nm), the presence of distinct pores (slope transitions), and structure factors (oscillation of the spectra). All slopes varied in the range of ,4.0 to ,2.5, with two clear common regions among species: d < 10 nm (slopes ,4, denoted as region I and also called the Porod region), and 10.0 < d < 40.0 nm (slopes ,2.9 to ,3.8, denoted as region II). The existence of these common regions suggests the presence of comparable form (region I) and structure (region II) factors, respectively the shape of the primary building units of the silica and the geometry of the pores. Contrast variation experiments using dibromomethane to fill pores in the SiO2 matrix showed that scattering was caused by pores rather than silica particles. Electron microscopic analysis confirmed the presence of circular, elliptical, and rectangular pores ranging in size from 3 to 65 nm, determining the structure factor. The fine architecture (length/width ratio of pore diameters) and distribution of the pores, however, seemed to be influenced by environmental factors, such as the salinity of and additions of AlCl3 to the growth medium. The results indicate that diatoms deposit silica with pores <50 nm in size and are highly homologous with respect to geometry. Consequently, it is suggested that in diatoms, whether pennate or centric, the formation of silica at a nanoscale level is a uniform process. [source] Predatory boreholes in Tournaisian (Lower Carboniferous) spiriferid brachiopodsLETHAIA, Issue 3 2009BERNARD MOTTEQUIN A brachiopod fauna from the uppermost part of the Tournaisian Tournai Formation (Belgium) contains an undetermined species of Crurithyris (Spiriferida, Ambocoeliidae), which displays numerous bored shells. About 8% of the 432 specimens with conjoined valves display single, small (, 1 mm) boreholes, which are smooth-sided, cylindrical or weakly conical, circular to slightly elliptical in plan view, perpendicular to the shell surface and generally complete. Of the 35 bored articulated specimens, 27 were drilled on the ventral valve. Most of the boreholes are located in the posterior half of the shell, and no case of edge-drilling has been observed. The boreholes were drilled by a predator, or possibly a parasite, which selected individuals greater than 2.5 mm long. Crurithyris sp. may have represented an attractive (in terms of energy cost) and easy target for a small-sized predator because of its thin shell and ornament of minute spines. [source] Quasistatic TEM characteristics of multilayer elliptical and cylindrical coplanar waveguidesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2004Volkan Akan Abstract Simple analytic CAD-oriented expressions are presented for calculating the quasistatic TEM parameters of multilayer elliptical coplanar waveguides (ME CPWs) and multilayer cylindrical coplanar waveguides (MC CPWs) by using the conformal mapping method. It is shown that the derived expressions are accurate and very simple for use in related applications. Comparisons have also been made between the results of this paper and those available in the literature. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 317,322, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20290 [source] Structure and dynamics of galaxies with a low surface-brightness disc , I. The stellar and ionized-gas kinematicsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008A. Pizzella ABSTRACT Photometry and long-slit spectroscopy are presented for a sample of six galaxies with a low surface-brightness stellar disc and a bulge. The characterizing parameters of the bulge and disc components were derived by means of a two-dimensional photometric decomposition of the images of the sample galaxies. Their surface-brightness distribution was assumed to be the sum of the contribution of a Sérsic bulge and an exponential disc, with each component being described by elliptical and concentric isophotes of constant ellipticity and position angle. The stellar and ionized-gas kinematics were measured along the major and minor axes in half of the sample galaxies, whereas the other half was observed only along two diagonal axes. Spectra along two diagonal axes were obtained also for one of the objects with major and minor axis spectra. The kinematic measurements extend in the disc region out to a surface-brightness level ,R, 24 mag arcsec,2, reaching in all cases the flat part of the rotation curve. The stellar kinematics turns out to be more regular and symmetric than the ionized-gas kinematics, which often shows the presence of non-circular, off-plane and non-ordered motions. This raises the question about the reliability of the use of the ionized gas as the tracer of the circular velocity in the modelling of the mass distribution, in particular in the central regions of low surface-brightness galaxies. [source] Is AGN feedback necessary to form red elliptical galaxies?MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008A. Khalatyan ABSTRACT We have used the smoothed particle hydrodynamics (SPH) code gadget-2 to simulate the formation of an elliptical galaxy in a group-size cosmological dark matter halo with mass Mhalo, 3 × 1012 h,1 M, at z= 0. The use of a stellar population synthesis model has allowed us to compute magnitudes, colours and surface brightness profiles. We have included a model to follow the growth of a central black hole and we have compared the results of simulations with and without feedback from active galactic nuclei (AGN). We have studied the interplay between cold gas accretion and merging in the development of galactic morphologies, the link between colour and morphology evolution, the effect of AGN feedback on the photometry of early-type galaxies, the redshift evolution in the properties of quasar hosts, and the impact of AGN winds on the chemical enrichment of the intergalactic medium (IGM). We have found that the early phases of galaxy formation are driven by the accretion of cold filamentary flows, which form a disc galaxy at the centre of the dark matter halo. Disc star formation rates in this mode of galaxy growth are about as high as the peak star formation rates attained at a later epoch in galaxy mergers. When the dark matter halo is sufficiently massive to support the propagation of a stable shock, the gas in the filaments is heated to the virial temperature, cold accretion is shut down, and the star formation rate begins to decline. Mergers transform the spiral galaxy into an elliptical one, but they also reactivate star formation by bringing gas into the galaxy. Without a mechanism that removes gas from the merger remnants, the galaxy ends up with blue colours, which are atypical for its elliptical morphology. We have demonstrated that AGN feedback can solve this problem even with a fairly low heating efficiency. Our simulations support a picture where AGN feedback is important for quenching star formation in the remnant of wet mergers and for moving them to the red sequence. This picture is consistent with recent observational results, which suggest that AGN hosts are galaxies in migration from the blue cloud to the red sequence on the colour,magnitude diagram. However, we have also seen a transition in the properties of AGN hosts from blue and star forming at z, 2 to mainly red and dead at z, 0. Ongoing merging is the primary but not the only triggering mechanism for luminous AGN activity. Quenching by AGN is only effective after the cold filaments have dried out, since otherwise the galaxy is constantly replenished with gas. AGN feedback also contributes to raising the entropy of the hot IGM by removing low-entropy tails vulnerable to developing cooling flows. We have also demonstrated that AGN winds are potentially important for the metal enrichment of the IGM a high redshift. [source] The mass assembly of fossil groups of galaxies in the Millennium simulationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2007Ali Dariush ABSTRACT The evolution of present-day fossil galaxy groups is studied in the Millennium simulation. Using the corresponding Millennium gas simulation and semi-analytic galaxy catalogues, we select fossil groups at redshift zero according to the conventional observational criteria, and trace the haloes corresponding to these groups backwards in time, extracting the associated dark matter, gas and galaxy properties. The space density of the fossils from this study is remarkably close to the observed estimates and various possibilities for the remaining discrepancy are discussed. The fraction of X-ray bright systems which are fossils appears to be in reasonable agreement with observations, and the simulations predict that fossil systems will be found in significant numbers (3,4 per cent of the population) even in quite rich clusters. We find that fossils assemble a higher fraction of their mass at high redshifts, compared to non-fossil groups, with the ratio of the currently assembled halo mass to final mass, at any epoch, being about 10,20 per cent higher for fossils. This supports the paradigm whereby fossils represent undisturbed, early-forming systems in which large galaxies have merged to form a single dominant elliptical. [source] The SAURON project , VIII.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2006OASIS/CFHT integral-field spectroscopy of elliptical, lenticular galaxy centres ABSTRACT We present high spatial resolution integral-field spectroscopy of 28 elliptical (E) and lenticular (S0) galaxies from the SAURON representative survey obtained with the OASIS spectrograph during its operation at the Canada,France,Hawaii Telescope. These seeing-limited observations explore the central 8 × 10 arcsec2 (typically 1 kpc diameter) regions of these galaxies using a spatial sampling four times higher than SAURON (0.27-arcsec versus 0.94-arcsec spatial elements), resulting in almost a factor of 2 improvement in the median point spread function. These data allow accurate study of the central regions to complement the large-scale view provided by SAURON. Here we present the stellar and gas kinematics, stellar absorption-line strengths and nebular emission-line strengths for this sample. We also characterize the stellar velocity maps using the ,kinemetry' technique, and derive maps of the luminosity-weighted stellar age, metallicity and abundance ratio via stellar population models. We give a brief review of the structures found in our maps, linking also to larger-scale structures measured with SAURON. We present two previously unreported kinematically decoupled components (KDCs) in the centres of NGC 3032 and NGC 4382. We compare the intrinsic size and luminosity-weighted stellar age of all the visible KDCs in the full SAURON sample, and find two types of components: kiloparsec-scale KDCs, which are older than 8 Gyr, and are found in galaxies with little net rotation; and compact KDCs, which have intrinsic diameters of less than a few hundred parsec, show a range of stellar ages from 0.5 to 15 Gyr (with 5/6 younger than 5 Gyr), are found exclusively in fast-rotating galaxies, and are close to counter-rotating around the same axis as their host. Of the seven galaxies in the SAURON sample with integrated luminosity-weighted ages less than 5 Gyr, five show such compact KDCs, suggesting a link between counter-rotation and recent star formation. We show that this may be due to a combination of small sample size at young ages, and an observational bias, since young KDCs are easier to detect than their older and/or corotating counterparts. [source] A Subaru/Suprime-Cam wide-field survey of globular cluster populations around M87 , I. Observation, data analysis and luminosity functionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006Naoyuki Tamura ABSTRACT In this paper and a companion paper, we report on a wide-field imaging survey of the globular cluster (GC) populations around M87 carried out with Suprime-Cam on the 8.2-m Subaru telescope. Here, we describe the observations, data reduction and data analysis, and present luminosity functions of GC populations around M87 and NGC 4552, another luminous Virgo elliptical in our survey field. The imaging data were taken in the B, V and I bands with a sky coverage of extending from the M87 centre out to ,0.5 Mpc. GC candidates were selected by applying a colour criterion on the B,V and V,I diagram to unresolved objects, which greatly reduces contamination. The data from control fields taken with Subaru/Suprime-Cam were also analysed for subtraction of contamination in the GC sample. These control field data are compatible with those in the M87 field in terms of the filter set (BVI), limiting magnitudes and image quality, which minimize the possibility of introducing any systematic errors into the subtractive correction. We investigate GC luminosity functions (GCLFs) at distances , 10 arcmin (,45 kpc) from the host galaxy centre in detail. By fitting Gaussians to the GCLFs, the V -band turnover magnitude (VTO) is estimated to be 23.62 ± 0.06 and 23.56 ± 0.20 mag for the GC population in M87 and NGC 4552, respectively. The GCLF is found to be a function of GC colour; VTO of the red GC subpopulation (V,I > 1.1) is fainter than that of the blue GC subpopulation (V,I, 1.1) in both M87 and NGC 4552, as expected if the colour differences are primarily due to a metallicity effect, and the mass functions of the two subpopulations are similar. The radial dependence of the GCLF is also investigated for the GC population in M87. The GCLF of each subpopulation at 1 ,R, 5 arcmin is compared to that at 5 ,R, 10 arcmin, but no significant trend with distance is found in the shape of the GCLF. We also estimate GC-specific frequencies (SN) for M87 and NGC 4552. The SN of the M87 GC population is estimated to be 12.5 ± 0.8 within 25 arcmin. The SN value of the NGC 4552 GC population is estimated to be 5.0 ± 0.6 within 10 arcmin. [source] A Subaru/Suprime-Cam wide-field survey of globular cluster populations around M87 , II.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006Colour, spatial distribution ABSTRACT We have performed a wide-field imaging survey of the globular cluster (GC) populations around M87 with Suprime-Cam on the 8.2-m Subaru Telescope. A field extending from the centre of M87 out to a radius of ,0.5 Mpc was observed through the BVI filters. By investigating the GC colour distribution as a function of distance from M87 and NGC 4552, another luminous Virgo elliptical in our survey field, it is found that clear bimodality [(V,I)peak, 1.0 and 1.2] is seen only in the inner regions (,10 kpc) of the host galaxies and that it becomes weaker with radius due to the decreasing contribution of the red GC (V,I > 1.1) subpopulation. It is also found (both around M87 and around NGC 4552) that while the spatial distribution of the red GCs is as centrally concentrated as the host galaxy halo light distribution, the distribution of the blue GCs (V,I, 1.1) tends to be more extended. However, the blue GC distribution around M87 is not as extended as the Virgo cluster mass density profile. Based on these facts, we argue that the contribution of GCs associated with the Virgo cluster [e.g. intergalactic GCs (i-GCs)] is not significant around M87 and is not the primary reason for the high SN value of M87. Instead, most of the blue GCs around luminous ellipticals, as well as the red GCs, are presumed to be associated with the host galaxy. We model the radial profile of GC surface densities out to ,0.5 Mpc from M87 by a superposition of the GC populations associated with M87 and with NGC 4552. It is found that there are some regions where the GC surface densities are larger than that which is expected from this model, suggesting the existence of an additional i-GC population independent of the luminous ellipticals. By comparing the estimated i-GC surface density with the luminosity density of the intracluster stellar population inferred from the intergalactic planetary nebulae in the Virgo cluster, we obtain a crude estimate of i-GC specific frequency SN= 2.9+4.2,1.5. If this SN value represents the stellar population tidally stripped by a massive central galaxy from other (less-luminous) galaxies, the contribution of tidally captured GCs in the GC population of M87 would need to be low to be consistent with the high SN value of M87. [source] An extensive study of dynamical friction in dwarf galaxies: the role of stars, dark matter, halo profiles and MONDMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006F. J. Sánchez-Salcedo ABSTRACT We investigate the in-spiralling time-scales of globular clusters (GCs) in dwarf spheroidal (dSph) and dwarf elliptical (dE) galaxies, due to dynamical friction (DF). We address the problem of these time-scales having been variously estimated in the literature as much shorter than a Hubble time. Using self-consistent two-component (dark matter and stars) models, we explore mechanisms which may yield extended DF time-scales in such systems in order to explain why dwarf galaxies often show GC systems. As a general rule, dark matter and stars both give a comparable contribution to the dynamical drag. By exploring various possibilities for their gravitational make-up, it is shown that these studies help to constrain the parameters of the dark matter haloes in these galaxies, as well as to test alternatives to dark matter. Under the assumption of a dark halo having a central density core with a typical King core radius somewhat larger than the observed stellar core radius, DF time-scales are naturally extended upwards of a Hubble time. Cuspy dark haloes yield time-scales ,4.5 Gyr, for any dark halo parameters in accordance with observations of stellar line-of-sight velocity dispersion in dSph galaxies. We confirm, after a detailed formulation of the DF problem under the alternative hypothesis of modified Newtonian dynamics (MOND) and in the lack of any dark matter, that due to the enhanced dynamical drag of the stars, the DF time-scales in MOND would be extremely short. Taking the well-measured structural parameters of the Fornax dSph and its GC system as a case study, we conclude that requiring DF time-scales comparable to the Hubble time strongly favours dark haloes with a central core. [source] The SAURON project , VI.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006Line strength maps of 48 elliptical, lenticular galaxies ABSTRACT We present absorption line strength maps of 48 representative elliptical and lenticular galaxies obtained as part of a survey of nearby galaxies using our custom-built integral-field spectrograph, SAURON, operating on the William Herschel Telescope. Using high-quality spectra, spatially binned to a constant signal-to-noise ratio, we measure four key age, metallicity and abundance ratio sensitive indices from the Lick/IDS system over a two-dimensional field extending up to approximately one effective radius. A discussion of calibrations and offsets is given, along with a description of error estimation and nebular emission correction. We modify the classical Fe5270 index to define a new index, Fe5270S, which maximizes the useable spatial coverage of SAURON. Maps of H,, Fe5015, Mg b and Fe5270S are presented for each galaxy. We use the maps to compute average line strengths integrated over circular apertures of one-eighth effective radius, and compare the resulting relations of index versus velocity dispersion with previous long-slit work. The metal line strength maps show generally negative gradients with increasing radius roughly consistent with the morphology of the light profiles. Remarkable deviations from this general trend exist, particularly the Mg b isoindex contours appear to be flatter than the isophotes of the surface brightness for about 40 per cent of our galaxies without significant dust features. Generally, these galaxies exhibit significant rotation. We infer from this that the fast-rotating component features a higher metallicity and/or an increased Mg/Fe ratio as compared to the galaxy as a whole. The H, maps are typically flat or show a mild positive outwards radial gradient, while a few galaxies show strong central peaks and/or elevated overall H, strength likely connected to recent star formation activity. For the most prominent post-starburst galaxies, even the metal line strength maps show a reversed gradient. [source] The SAURON project , IV.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006The mass-to-light ratio, lenticular galaxies, the Fundamental Plane of elliptical, the virial mass estimator ABSTRACT We investigate the well-known correlations between the dynamical mass-to-light ratio (M/L) and other global observables of elliptical (E) and lenticular (S0) galaxies. We construct two-integral Jeans and three-integral Schwarzschild dynamical models for a sample of 25 E/S0 galaxies with SAURON integral-field stellar kinematics to about one effective (half-light) radius Re. They have well-calibrated I -band Hubble Space Telescope WFPC2 and large-field ground-based photometry, accurate surface brightness fluctuation distances, and their observed kinematics is consistent with an axisymmetric intrinsic shape. All these factors result in an unprecedented accuracy in the M/L measurements. We find a tight correlation of the form (M/L) = (3.80 ± 0.14) × (,e/200 km s,1)0.84±0.07 between the M/L (in the I band) measured from the dynamical models and the luminosity-weighted second moment ,e of the LOSVD within Re. The observed rms scatter in M/L for our sample is 18 per cent, while the inferred intrinsic scatter is ,13 per cent. The (M/L),,e relation can be included in the remarkable series of tight correlations between ,e and other galaxy global observables. The comparison of the observed correlations with the predictions of the Fundamental Plane (FP), and with simple virial estimates, shows that the ,tilt' of the FP of early-type galaxies, describing the deviation of the FP from the virial relation, is almost exclusively due to a real M/L variation, while structural and orbital non-homology have a negligible effect. When the photometric parameters are determined in the ,classic' way, using growth curves, and the ,e is measured in a large aperture, the virial mass appears to be a reliable estimator of the mass in the central regions of galaxies, and can be safely used where more ,expensive' models are not feasible (e.g. in high-redshift studies). In this case the best-fitting virial relation has the form (M/L)vir= (5.0 ± 0.1) ×Re,2e/(LG), in reasonable agreement with simple theoretical predictions. We find no difference between the M/L of the galaxies in clusters and in the field. The comparison of the dynamical M/L with the (M/L)pop inferred from the analysis of the stellar population, indicates a median dark matter fraction in early-type galaxies of ,30 per cent of the total mass inside one Re, in broad agreement with previous studies, and it also shows that the stellar initial mass function varies little among different galaxies. Our results suggest a variation in M/L at constant (M/L)pop, which seems to be linked to the galaxy dynamics. We speculate that fast-rotating galaxies have lower dark matter fractions than the slow-rotating and generally more-massive ones. If correct, this would suggest a connection between the galaxy assembly history and the dark matter halo structure. The tightness of our correlation provides some evidence against cuspy nuclear dark matter profiles in galaxies. [source] Constraining the star formation histories of spiral bulgesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2000R. N. Proctor Stellar populations in spiral bulges are investigated using the Lick system of spectral indices. Long-slit spectroscopic observations of line strengths and kinematics made along the minor axes of four spiral bulges are reported. Comparisons are made between central line strengths in spiral bulges and those in other morphological types [elliptical, spheroidal (Sph) and S0]. The bulges investigated are found to have central line strengths comparable to those of single stellar populations of approximately solar abundance or above. Negative radial gradients are observed in line strengths, similar to those exhibited by elliptical galaxies. The bulge data are also consistent with correlations between Mg2, Mg2 gradient and central velocity dispersion observed in elliptical galaxies. In contrast to elliptical galaxies, central line strengths lie within the loci defining the range of ,Fe, and Mg2 achieved by Worthey's solar abundance ratio, single stellar populations (SSPs). The implication of solar abundance ratios indicates significant differences in the star formation histories of spiral bulges and elliptical galaxies. A ,single zone with infall' model of galactic chemical evolution, using Worthey's SSPs, is used to constrain the possible star formation histories of our sample. We show that the ,Fe,, Mg2 and H, line strengths observed in these bulges cannot be reproduced using primordial collapse models of formation but can be reproduced by models with extended infall of gas and star formation (2,17 Gyr) in the region modelled. One galaxy (NGC 5689) shows a central population with a luminosity-weighted average age of ,5 Gyr, supporting the idea of extended star formation. Kinematic substructure, possibly associated with a central spike in metallicity, is observed at the centre of the Sa galaxy NGC 3623. [source] SDSS J150634.27+013331.6: the second compact elliptical galaxy in the NGC 5846 group,MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2010Igor V. Chilingarian ABSTRACT We report the discovery of the second compact elliptical (cE) galaxy SDSS J150634.27+013331.6 in the nearby NGC 5846 group by the Virtual Observatory (VO) workflow. This object (MB=,15.98 mag, Re= 0.24 kpc) becomes the fifth cE where the spatially resolved kinematics and stellar populations can be obtained. We used archival HST WFPC2 images to demonstrate that its light profile has a two-component structure, and integrated photometry from GALEX, SDSS, UKIDSS and Spitzer to build the multiwavelength spectral energy distribution to constrain the star formation history (SFH). We observed this galaxy with the PMAS IFU spectrograph at the Calar-Alto 3.5-m telescope and obtained two-dimensional maps of its kinematics and stellar population properties using the full-spectral fitting technique. Its structural, dynamical and stellar population properties suggest that it had a massive progenitor heavily tidally stripped by NGC 5846. [source] The dark halo of the main lens galaxy in QSO 0957 + 561MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2005L. J. Goicoechea ABSTRACT We present an analysis of infrared/optical/ultraviolet spectra of the two images of the first gravitationally lensed quasar Q0957 + 561A,B. The Hubble Space Telescope observations of Q0957 + 561A and Q0957 + 561B are separated in time by the known time delay in this system, so we can directly deduce the flux ratios. These flux ratios of images lead to important information on the dark halo of the main lens galaxy (a giant elliptical at redshift z= 0.36). Our measurements for the continuum are in good agreement with extinction in the elliptical galaxy and a small fraction of mass in collapsed objects (no need for gravitational microlensing). From the continuum and emission-line ratios, we also show evidence in favour of the existence of a network of compact dusty clouds. [source] A NEW SPINICAUDATAN GENUS (CRUSTACEA: ,CONCHOSTRACA') FROM THE LATE CRETACEOUS OF MADAGASCARPALAEONTOLOGY, Issue 5 2008ALYCIA L. STIGALL Abstract:, A new spinicaudatan genus and species, Ethmosestheria mahajangaensis gen. et sp. nov., is described from the Anembalemba Member (Upper Cretaceous, Maastrichtian) of the Maevarano Formation, Mahajanga Basin, Madagascar. This is the first spinicaudatan reported from the post-Triassic Mesozoic of Madagascar. The new species is assigned to the family Antronestheriidae based on the cavernous or sievelike ornamentation on the carapace. Of well-documented Mesozoic spinicaudatan genera, Ethmosestheria mahajangaensis is most closely related to Antronestheria Chen and Hudson from the Great Estuarine Group (Jurassic) of Scotland. However, relatively poor documentation of the ornamentation of most Gondwanan Mesozoic spinicaudatan species precludes detailed comparison among taxa. Ethmosestheria mahajangaensis exhibits ontogenetic trends in carapace growth: a change in carapace outline from subcircular/subelliptical to elliptical, and from very wide juvenile growth bands to narrow adult growth bands. Ornamentation style, however, does not vary with ontogeny. Ethmosestheria mahajangaensis individuals lived in temporary pools in a broad channel-belt system within a semiarid environment; preserved desiccation structures on carapaces indicate seasonal drying out of pools within the river system. Specimens of Ethmosestheria mahajangaensis are preserved with exquisite detail in debris flow deposits; these are the first spinicaudatans reported from debris flow deposits. These deposits also contain a varied vertebrate fauna, including dinosaurs, crocodyliforms, turtles, and frogs. Rapid entombment of the spinicaudatan carapaces likely promoted early fossil diagenesis leading to highly detailed preservation. [source] Morphometric and spatial analysis of thaw lakes and drained thaw lake basins in the western Arctic Coastal Plain, AlaskaPERMAFROST AND PERIGLACIAL PROCESSES, Issue 4 2005K. M. Hinkel Abstract Landsat-7 ETM,+ scenes were acquired for the western Arctic Coastal Plain of Alaska extending from 152° to 162° W longitude. A segmentation algorithm was used to classify lakes and drained thaw lake basins (DTLBs) exceeding 1,ha in size. A total of 13,214 lakes and 6539 DTLBs were identified. Several indices were obtained from the image processing software and used for a comparative analysis of lakes and basins including object size, goodness of elliptic fit, shape complexity, shape asymmetry, and orientation of the major axis. Nonparametric statistical analyses indicate that lakes and basins share similar orientation only. Three subregions of the western Arctic Coastal Plain were identified based on landscape age, as demarcated by ancient shorelines. The surfaces become progressively older inland and include the Younger Outer Coastal Plain, the Outer Coastal Plain, and the oldest Inner Coastal Plain. Lakes and basins in all subregions have statistically similar orientation, indicating that summer wind direction has not changed appreciably over the past several thousand years. Basin orientation is less clustered than lake orientation. Lakes are highly elliptical, while basins have more complex shapes. Lake coverage (%) is fairly constant across the three subregions, while DTLB coverage decreases on older surfaces. Lake and basin size decreases on progressively older surfaces, but the number of features per unit area increases. It is uncertain if surface age is responsible for differences in regional metrics as an analysis of the Inner Coastal Plain demonstrates significant internal variation. Distance from the coast, ground ice content, surficial sediments, and local relief may also influence lake morphometry. Copyright © 2005 John Wiley & Sons, Ltd. [source] Geissleria gereckei sp. nov. (Bacillariophyta) from leaf-litter covered stones of very shaded carbonate mountain springs with extremely low dischargePHYCOLOGICAL RESEARCH, Issue 3 2009Marco Cantonati SUMMARY A new benthic freshwater diatom, Geissleria gereckei sp. nov., was identified from light and scanning electron micrographs. The most characteristic morphological features are the valve outline (elliptical, but with lateral margins that can range from slightly convex to slightly concave and also straight, and protracted, almost capitate ends), the size and length/width ratio, and the pattern of the striae around the central area. The new species was found to be epilithic, and characteristic of leaf-litter covered stones of very shaded carbonate mountain springs of the Italian Alps with extremely-low discharge (likely to be affected by seasonal desiccation). Very-low-discharge springs host a highly specialized diatom microflora, and are likely to increase in number in the near future due to the reduction of water, which is predicted to be caused by climate change in many regions. [source] First record of Asteronema rhodochortonoides (Phaeophyceae) for the Pacific OceanPHYCOLOGICAL RESEARCH, Issue 4 2001Kazuhiro Kogame SUMMARY Morphological observations of a minute, filamentous, branched brown alga epiphytic on Sargassum thun-bergii (Mertens ex Roth) Kuntze were made on material collected at Tsuyazaki (33°48,N, 130°27,E), Fukuoka Prefecture, southern Japan. This alga was assignable to Asteronema rhodochortonoides (Břrgesen) Möller et Parodi in having stellately arranged chloroplasts with several pyrenoids grouped in the center, predominantly apical growth, narrow filaments, and elliptical or broadly elliptical plurilocular zoidangia that are apically or laterally formed on upright filaments. A comparison of partial nuclear small subunit rDNA sequences between the Japanese material and A. rhodochortonoides from the Canary Islands showed only two or three nucleotide differences. This supports our assignment of the Japanese material to this species as a first report for the Pacific Ocean. In laboratory cultures, zoids released from plurilocular zoidangia developed into plants with morphology similar to the field-collected plants. This cycle repeated without production of unilocular zoidangia in our cultures. [source] The influence of dipolar interaction on magnetic properties in nanomagnets with different shapesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2010Ying Li Abstract With the Monte Carlo method, we investigate the magnetic properties of four nanomagnets of different shapes, i.e., the circular-shaped, the square-shaped, the elliptical, and the ring-shaped nanomagnets. A systematic study of the effects of the dipolar interaction on the magnetic configurations is performed in these nanomagnets, and further the coercive field and the remanence as a function of dipolar interaction are analyzed. The results show that the magnetic configuration and thus the magnetization reversal process of nanomagnets are dependent strongly on the strength of dipolar interactions. For the case of small dipolar interaction, the magnetization reversal process is mainly dominated by spin rotation, while the reversal transforms to the vortex nucleation and propagation formations with increasing dipolar interaction. Moreover, if the dipolar interaction is neglected in the calculation of the total energy, no clear difference is found among hysteresis loops of four nanomagnets with same areas, but the inclusion of dipolar interaction can lead to different hysteresis loops for nanomagnets with same areas but different shapes. This indicates that the dipolar interaction is important for accounting for the shape effect of the magnetic properties in nanomagnets. [source] Two related lithium calixarene complexes, [p-tert -butylcalix[4]arene(OMe)(OH)2(OLi)]2·4MeCN and {p-tert -butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}2·8MeCN, determined using synchrotron radiationACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Darren S. Lee The crystal structures of acetonitrile solvates of two related lithium calixarene complexes have been determined by low-temperature single-crystal X-ray diffraction using synchrotron radiation. Bis(,-5,11,17,23-tetra- tert -butyl-26,28-dihydroxy-25-methoxy-27-oxidocalix[4]arene)dilithium(I) acetonitrile tetrasolvate, [Li2(C45H57O4)2]·4C2H3N or [p-tert -butylcalix[4]arene(OMe)(OH)2(OLi)]2·4MeCN, (I), crystallizes with the complex across a centre of symmetry and with four molecules of unbound acetonitrile of crystallization per complex. Tetraacetonitrilebis(,-5,11,17,23-tetra- tert -butyl-26,28-dihydroxy-25,27-dioxidocalix[4]arene)tetralithium(I) acetonitrile octasolvate, [Li4(C44H54O4)2(C2H3N)4]·8C2H3N or {p-tert -butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}2·8MeCN, (II), also crystallizes with the complex lying across a centre of symmetry and contains eight molecules of unbound acetonitrile per complex plus four more directly bound to two of the lithium ions, two on each ion. The cores of both complexes are partially supported by O,H...O hydrogen bonds. The methoxy methyl groups in (I) prevent the binding of any more than two Li+ ions, while the corresponding two O-atom sites in (II) bind an extra Li+ ion each, making four in total. The calixarene cone adopts an undistorted cone conformation in (I), but an elliptical one in (II). [source] ERROR SPACE MOTION CONTROL METHODOLOGY FOR COMPLEX CONTOURSASIAN JOURNAL OF CONTROL, Issue 1 2005Robert G. Landers ABSTRACT Motion control is a critical component of many engineering systems (e.g., manufacturing, robotics). Most systems have standard interpolation and control schemes for linear and circular contours; therefore, complex contours are often decomposed into a series of line segments and circular arcs. However, there are discontinuities where the line segments and arcs are joined together, and time to complete the contour is substantially increased when acceleration/deceleration interpolation schemes are employed. A motion control scheme known as the error space motion control methodology is proposed in this paper to design servomechanism motion control systems that may be utilized for complex contours. The error space motion control methodology is applied to a two-axis motion control system and simulation studies are conducted for linear, circular, elliptical, and limacon contours. The results demonstrate the excellent tracking ability of the proposed error space motion control methodology and its utility for complex contours. [source] The evolution of spheroidal galaxies in different environmentsASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009A. Fritz Abstract We analyse the kinematic and chemical evolution of 203 distant spheroidal (elliptical and S0) galaxies at 0.2 < z < 0.8 which are located in different environments (rich clusters, low-mass clusters and in the field). VLT/FORS and CAHA/MOSCA spectra with intermediate-resolution have been acquired to measure the internal kinematics and stellar populations of the galaxies. From HST/ACS and WFPC2 imaging, surface brightness profiles and structural parameters were derived for half of the galaxy sample. The scaling relations of the Faber-Jackson relation and Kormendy relation as well as the Fundamental Plane indicate a moderate evolution for the whole galaxy population in each density regime. In all environments, S0 galaxies show a faster evolution than elliptical galaxies. For the cluster galaxies a slight radial dependence of the evolution out to one virial radius is found. Dividing the samples with respect to their mass, a mass dependent evolution with a stronger evolution of lower-mass galaxies (M < 2 × 1011 M,) is detected. Evidence for recent star formation is provided by blue colours and weak [OII] emission or strong H, absorption features in the spectra. The results are consistent with a down-sizing formation scenario which is independent from the environment of the galaxies (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comparative floral anatomy of PontederiaceaeBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2004AMY STRANGE Floral anatomy is described in eight species (representing five genera) of Pontederiaceae, and floral ontogeny is described in Pontederia cordata. The results are assessed in the context of recent phylogenetic work on Pontederiaceae, which indicates that the unilocular ovary condition has been achieved by two different, non-homologous routes in Pontederiaceae: via loss of interlocular septa in Heteranthera and Hydrothrix, and via pseudomonomery in Pontederia, which has a single fertile carpel. Absence of septal nectaries has evolved more than once in Pontederiaceae, at least in Heterantha and Monochoria, probably due to a transfer of the insect reward from nectar to pollen in these taxa. The presence of an elliptical or linear unvascularized appendage on the abaxial outer stamen in Monochoria is also probably correlated with enantiostyly. In Pontederia, air spaces in the ovary wall are modified into canals, each with a ring of apparently secretory epithelial cells. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 144, 395,408. [source] | |||||||||||||||||||||||||