2,260 research outputs found
The orientation of galaxy pairs with filamentary structures: dependence on morphology
Aims. With the aim of performing an analysis of the orientations of galaxy
pair systems with respect to the underlying large-scale structure, we study the
alignment between the axis connecting the pair galaxies and the host cosmic
filament where the pair resides. In addition, we analyze the dependence of the
amplitude of the alignment on the morphology of pair members as well as
filament properties. Methods. We build a galaxy pair catalog requiring r_p <
100\kpc and \Delta V < 500 \kms within redshift from the Sloan
Digital Sky Survey (SDSS). We divided the galaxy pair catalog taking into
account the morphological classification by defining three pair categories
composed by elliptical-elliptical (E-E), elliptical-spiral (E-S) and
spiral-spiral (S-S) galaxies. We use a previously defined catalog of filaments
obtained from SDSS and we select pairs located closer than 1\mpc from the
filament spine, which are considered as members of filaments. For these pairs,
we calculate the relative angle between the axis connecting each galaxy, and
the direction defined by the spine of the parent filament.
Results. We find a statistically significant alignment signal between the
pair axes and the spine of the host filaments consistent with a relative excess
of 15\% aligned pairs. We obtain that pairs composed by elliptical
galaxies exhibit a stronger alignment, showing a higher alignment signal for
pairs closer than 200 \kpc to the filament spine. In addition, we find that
the aligned pairs are associated with luminous host filaments populated with a
high fraction of elliptical galaxies.
The findings of this work show that large scale structures play a fundamental
role in driving galactic anisotropic accretion as induced by galaxy pairs
exhibiting a preferred alignment along the filament direction.Comment: 8 pages, 6 figures. Accepted for publication in A&
Polarization Properties of Extragalactic Radio Sources and Their Contribution to Microwave Polarization Fluctuations
We investigate the statistical properties of the polarized emission of
extragalactic radio sources and estimate their contribution to the power
spectrum of polarization fluctuations in the microwave region. The basic
ingredients of our analysis are the NVSS polarization data, the multifrequency
study of polarization properties of the B3-VLA sample (Mack et al. 2002) which
has allowed us to quantify Faraday depolarization effects, and the 15 GHz
survey by Taylor et al. (2001), which has provided strong constraints on the
high-frequency spectral indices of sources. The polarization degree of both
steep- and flat-spectrum at 1.4 GHz is found to be anti-correlated with the
flux density. The median polarization degree at 1.4 GHz of both steep- and
flat-spectrum sources brighter than mJy is . The data by Mack et al. (2002) indicate a substantial mean Faraday
depolarization at 1.4 GHz for steep spectrum sources, while the depolarization
is undetermined for most flat/inverted-spectrum sources. Exploiting this
complex of information we have estimated the power spectrum of polarization
fluctuations due to extragalactic radio sources at microwave frequencies. We
confirm that extragalactic sources are expected to be the main contaminant of
Cosmic Microwave Background (CMB) polarization maps on small angular scales. At
frequencies GHz the amplitude of their power spectrum is expected to be
comparable to that of the -mode of the CMB. At higher frequencies, however,
the CMB dominates.Comment: 10 pages, A&A in pres
Fracturas estallido de columna toracolumbar: Evaluación clinicoradiológica y terapéutica de 90 casos
Presentamos un estudio retrospectivo de 90 fracturas toracolumbares tipo estallido con un seguimiento mínimo de 12 meses. Se realizó tratamiento ortopédico en 43 casos y en 47 se indicó una artrodesis instrumentada. Realizamos una evaluación clínico-radiológica en base al dolor residual y evolución del ángulo de cifosis con el objetivo de valorar el tratamiento ortopédico como opción terapéutica y la necesidad de distinguir fracturas estallido con afectación de 2 ó 3 columnas. No apreciamos diferencias estables significativas en el dolor y la lesión de las tres columnas. El aumento de cifosis angular media en las fracturas estallido estable no operadas es de 4.7º y de 5.2º en las fracturas estallido inestables tratadas ortopédicamente. Observamos una alta incidencia de complicaciones relacionadas con la fijación (21%) cuando la fractura asentaba en la charnela y se instrumentaba a un solo nivel. El tratamiento ortopédico es una opción aceptable en las fracturas estallido en pacientes neurológicamente indemnes.Ninety burst fractures of the thoracolumbar spine were retrospectively assessed with a minum follow-up of 12 months. Conservative treatment was indicated in 43 cases, and reduction and surgical stabilization in 47. The aim was to compare the two treatment modalities according to fracture stability. Clinical and radiological evaluation included chronic pain and kyphotic angle progression. No statistical differences were found between stable and unstable fractures as to chronic pain. The kyphotic angle average progression for stable burst fractures was 4.7º and 5.2º for unstable fractures conservatively treated. There was a high rate of complications related to instrumentation (21%) particularly when the fracture was at the thoracolumbar junction and a single level was fixed. The orthopaedic treatment is an acceptable alternative treatment for stable burst fractures without neurological injury
Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution
We present C and O abundances in the Magellanic Clouds derived from deep
spectra of HII regions. The data have been taken with the Ultraviolet-Visual
Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in
the Large Magellanic Cloud (LMC) and 4 in the Small Magellanic Cloud (SMC). We
measure pure recombination lines (RLs) of CII and OII in all the objects,
permitting to derive the abundance discrepancy factors (ADFs) for O^2+, as well
as their O/H, C/H and C/O ratios. We compare the ADFs with those of other HII
regions in different galaxies. The results suggest a possible metallicity
dependence of the ADF for the low-metallicity objects, but more uncertain for
high-metallicity objects. We compare nebular and B-type stellar abundances and
we find that the stellar abundances agree better with the nebular ones derived
from collisionally excited lines (CELs). Comparing these results with other
galaxies we observe that stellar abundances seem to agree better with the
nebular ones derived from CELs in low-metallicity environments and from RLs in
high-metallicity environments. The C/H, O/H and C/O ratios show almost flat
radial gradients, in contrast with the spiral galaxies where such gradients are
negative. We explore the chemical evolution analysing C/O vs. O/H and comparing
with the results of HII regions in other galaxies. The LMC seems to show a
similar chemical evolution to the external zones of small spiral galaxies and
the SMC behaves as a typical star-forming dwarf galaxy.Comment: Accepted for publication in MNRAS, 17 pages, 11 figures, 8 table
Positive affect and functional somatic symptoms in young adults
Background Functional Somatic Symptoms (FSS) are symptoms for which an underlying pathology cannot be found. High negative affect (NA) has been linked to the etiology of FSS, but little is known about the role of Positive Affect (PA). Objective: The aim of this study was to test if PA is related to current and future lower levels of FSS. We also examined the interactions between PA and NA, and PA and sex on FSS. Method: Data from the Dutch Tracking Adolescents' Individual Lives Survey (TRAILS) cohort were used (N = 1247 cases, 60% females, mean age T5 = 22.2, T6 = 25.6). PA was measured with the PANAS schedule and FSS with the Adult Self Report questionnaire (ASR). A Principal Component Analysis (PCA) was performed on the physical complaints subscale of the ASR. Regression analyses with bootstrapping were performed to assess the associations and interactions. Results: PA had a significant negative association with current FSS when adjusted for NA, age, sex and socioeconomic status (B = 0.004; BCa 95% CI = [ -0.006; -0.002]), but the association was not significant longitudinally. No interactions were found. In secondary analysis, PA was significantly related to the component "General Physical Symptoms" (B = -0.019; BCa 95% CI = [ -0.0028; -0.011]) but not to the component "Gastrointestinal Symptoms" (B = -0.008; BCa 95% CI = [ -0.016;0.001]) in the cross-sectional analysis. Conclusion: In conclusion, high PA was significantly related to current lower levels of FSS, but the effect was small. Further research on individual variations in affect is needed to obtain more insight in their contribution to FSS
Childhood Cancer Survival in the Highly Vulnerable Population of South Texas: Persistent Challenges for Adolescents and Hispanic Ethnicity
Background: This study examines childhood cancer survival rates and prognostic factors related to survival in the majority Hispanic population of South Texas (STX), whereas most other population studies in childhood cancer survival focus on populations with relatively few Hispanics.
Methods: The population-based cohort study used Texas Cancer Registry data (1995-2017) to examine survival and prognostic factors.
Results: The 5-year relative survival rate for STX cancer patients diagnosed at 0–19 years was 80.3% for all races/ethnicity. Hispanics had statistically significant lower 5-year relative survival rates than non-Hispanic Whites (NHW) for male and female together diagnosed at age ≥ 5 years. When comparing survival among Hispanics and NHW for the most common cancer, acute lymphocytic leukemia (ALL), the difference was most striking in the 15-19 years age range, with 47.7% Hispanic patients surviving at 5 years compared to 78.4% of NHW counterparts. The multivariable-adjusted analysis showed that males [hazard ratio (HR): 1.13], patients diagnosed at age \u3c 1 year (HR: 1.69), at 10–14 year (HR: 1.42), or at 15–19 years (HR: 1.40), and Hispanics (HR: 1.38) had significantly increased mortality risk compared to the corresponding counterparts for all cancers.
Conclusions: STX Hispanics had lower 5-year relative survival than NHW especially for ALL. Male gender, diagnosis at age \u3c 1 year or 10–19 years were also associated with decreased childhood cancer survival. Despite advances in treatment, Hispanics lag significantly behind NHW. Further cohort studies in STX are warranted to identify additional factors affecting survival and to develop interventional strategies
Improving the Measurement of Functional Somatic Symptoms With Item Response Theory
More than 40 questionnaires have been developed to assess functional somatic symptoms (FSS), but there are several methodological issues regarding the measurement of FSS. We aimed to identify which items of the somatization subscale of the Symptom Checklist-90 (SCL-90) are more informative and discriminative between persons at different levels of severity of FSS. To this end, item response theory was applied to the somatization scale of the SCL-90, collected from a sample of 82,740 adult participants without somatic conditions in the Lifelines Cohort Study. Sensitivity analyses were performed with all the participants who completed the somatization scale. Both analyses showed that Items 11 "feeling weak physically" and 12 "heavy feelings in arms or legs" were the most discriminative and informative to measure severity levels of FSS, regardless of somatic conditions. Clinicians and researchers may pay extra attention to these symptoms to augment the assessment of FSS
Exploitation of washing products of granitic tin-bearing sands from Conquista (Córdoba)
8 páginas, 10 figuras, 3 tablas, 21 referencias.[EN]: An argillaceous material, high in kaolinite, from washing products of granitic sands of Pedroches (Córdoba) formation, is studied. The following determinations were carried out: mechanical analysis, chemical analysis. X-ray diffraction study, DTA-TG and dilatometric analysis, as well as a ceramic study of pressed and fîred bodies for two hours up to 1.300°C, to obttain the sintering diagrams.
Through mineralogical analysis, it is concluded that the raw material is very high in kaolinite with variable contents of quartz, illite, feldspars (potassic), an iron oxides (~5% F2O3) mainly as gel.
Through firing up to 1.300°C of presssed bodies, we can observe by the X-ray study the appearance and development of new phases among which mullite stands out, together with great vitreous phase formation.
The location and great potential of the deposit, as well as the good ceramic properties of this material, permit their use in the good ceramic properties of this material, permit their use in the floor and tile industry due to its iron oxide content, being possible the processing by pressing, extrusion and slip casting.[ES]: Se estudia un material arcilloso con alto contenido en caolinita, procedente del lavado de arenas graníticas de la formación de Los Pedroches (Córdoba). Se han realizado las siguientes determinaciones: análisis granulométrico, químico y mediante difracción de rayos X, estudio térmico por ATD-TG y dilatométrico, así como estudio de las propiedades cerámicas del material en probetas prensadas y cocidas durante dos horas hasta la temperatura de 1.300°C, obteniéndose los correspondientes diagramas de gresificación.
El análisis mineralógico del material crudo lo señala,como altamente caolinítico, con variable contenido eh cuarzo, ilita, feldespatos (potásicos) y óxidos de hierro (~5% F2O3), en estado de gel en su mayor parte.
Mediante cocción hasta 1.300°C de las probetas prensadas, el estudio mediante difracción de rayos X permite observar la aparición y desarrollo de nuevas fases, entre las que destaca la mullita, junto con abundante formación de fase vítrea.
La situación y gran potencia del yacimiento, así como las buenas propiedades cerámicas de este material natural, permiten su empleo en la industria de pavimentos y revestimientos cerámicos gresificados de pasta roja dado su contenido en óxidos de hierro que preparados adecuadamente pueden modelarse por prensado, extrusión y colaje.Peer reviewe
Connection Between Type A and E Factorizations and Construction of Satellite Algebras
Recently, we introduced a new class of symmetry algebras, called satellite
algebras, which connect with one another wavefunctions belonging to different
potentials of a given family, and corresponding to different energy
eigenvalues. Here the role of the factorization method in the construction of
such algebras is investigated. A general procedure for determining an so(2,2)
or so(2,1) satellite algebra for all the Hamiltonians that admit a type E
factorization is proposed. Such a procedure is based on the known relationship
between type A and E factorizations, combined with an algebraization similar to
that used in the construction of potential algebras. It is illustrated with the
examples of the generalized Morse potential, the Rosen-Morse potential, the
Kepler problem in a space of constant negative curvature, and, in each case,
the conserved quantity is identified. It should be stressed that the method
proposed is fairly general since the other factorization types may be
considered as limiting cases of type A or E factorizations.Comment: 20 pages, LaTeX, no figure, to be published in J. Phys.
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