1,595 research outputs found
Spectral Analysis of the Stromlo-APM Survey I. Spectral Properties of Galaxies
We analyze spectral properties of 1671 galaxies from the Stromlo-APM survey,
selected to have 15 < b_J < 17.15 and having a mean redshift z = 0.05. This is
a representative local sample of field galaxies, so the global properties of
the galaxy population provide a comparative point for analysis of more distant
surveys. We measure Halpha, Oii 3727, Sii 6716, 6731, Nii 6583 and Oi 6300
equivalent widths and the D_4000 break index. The 5A resolution spectra use an
8 arcsec slit, which typically covers 40-50% of the galaxy area. We find no
evidence for systematic trends depending on the fraction of galaxy covered by
the slit, and further analysis suggests that our spectra are representative of
integrated galaxy spectra.
We classify spectra according to their Halpha emission, which is closely
related to massive star formation. Overall we find 61% of galaxies are Halpha
emitters with rest-frame equivalent widths EW(Halpha) >= 2A. The emission-line
galaxy (ELG) fraction is smaller than seen in the CFRS at z = 0.2 and is
consistent with a rapid evolution of Halpha luminosity density. The ELG
fraction, and EW(Halpha), increase at fainter absolute magnitudes, smaller
projected area and smaller D_4000. In the local Universe, faint, small galaxies
are dominated by star formation activity, while bright, large galaxies are more
quiescent. This picture of the local Universe is quite different from the
distant one, where bright galaxies appear to show rapidly-increasing activity
back in time.
(Abridged)Comment: 40 pages, 25 figures, MNRAS, in pres
Biological stress regulation in female adolescents: a key role for confiding
Attachment behaviors play a critical role in regulating emotion within the context of close relationships, and attachment theory is currently used to inform evidence-based practice in the areas of adolescent health and social care. This study investigated the association between female adolescents’ interview-based attachment behaviors and two markers of hypothalamic–pituitary–adrenal axis activity: cortisol and dehydroepiandrosterone (DHEA). Unlike the classic stress hormone cortisol, there is very limited investigation of DHEA—a quintessential developmental hormone—in relation to attachment, especially in adolescents. Fifty-five healthy females mean age 14.36 (±2.41) years participated in the attachment style interview. A smaller cortisol awakening response was related to anxious attachment attitudes, including more fear of rejection, whereas greater morning basal DHEA secretion was only predicted by lower levels of reported confiding in one’s mother. These attachment–hormone relationships may be developmental markers in females, as they were independent of menarche status. These findings highlight that the normative shifts occurring in attachment to caregivers around adolescence are reflected in adolescents’ biological stress regulation. We discuss how studying these shifts can be informed by evolutionary– developmental theory
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Neuropsychological profile of patients with normal pressure hydrocephalus and Alzheimer's disease
RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Neuropsychological profile of patients with normal pressure hydrocephalus and Alzheimer's disease
RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Mecanismos de transmisión de la política monetaria y el impacto de una devaluación en el nivel de las firmas
La presente investigación examina distintas evidencias sobre la existencia del canal de hoja de balance en el nivel de firmas en la economía peruana. Mediante el empleo de modelos de panel estáticos y dinámicos y una muestra de 2 054 empresas no financieras, con información anual para el intervalo entre 1997 y 2001, se valida el funcionamiento de dicho canal, con efectos asimétricos de la emisión primaria y la devaluación real a través del nivel de endeudamiento y su costo implícito.
Human immunodeficiency virus rebound after suppression to < 400 copies/mL during initial highly active antiretroviral therapy regimens, according to prior nucleoside experience and duration of suppression
This study evaluated 1433 human immunodeficiency virus (HIV)-infected patients starting highly active antiretroviral therapy (HAART), 409 (28%) of whom had prior nucleoside experience and achieved an HIV load of <400 copies/mL by 24 weeks of therapy. Three hundred seven patients experienced virus rebound during a total of 2773.3 person-years of follow-up. There was a higher rate of virus rebound among the patients with pre-HAART nucleoside experience (relative hazard [RH], 2.86; 95% confidence interval, 2.22-3.84; P < .0001) and a decreasing rate of virus rebound with increasing duration of virus suppression (i.e., time since achieving a virus load of <400 HIV RNA copies/mL) among both the nucleoside-experienced and naive patients (P < .0001), but the difference between the groups persisted into the third year of follow-up (P = .0007). Even patients who had experienced <2 months of nucleoside therapy before beginning HAART had an increased risk of virus rebound (RH, 1.95; P = .009). It appears that only a small period of pre-HAART nucleoside therapy is sufficient to confer a disadvantage, in terms of risk of virus rebound, that persists for several years
The Clustering of Colour Selected Galaxies
We present measurements of the angular correlation function of galaxies
selected from a B_J=23.5 multicolour survey of two 5 degree by 5 degree fields
located at high galactic latitudes. The galaxy catalogue of approximately
400,000 galaxies is comparable in size to catalogues used to determine the
galaxy correlation function at low-redshift. Measurements of the z=0.4
correlation function at large angular scales show no evidence for a break from
a power law though our results are not inconsistent with a break at >15 Mpc.
Despite the large fields-of-view, there are large discrepancies between the
measurements of the correlation function in each field, possibly due to dwarf
galaxies within z=0.11 clusters near the South Galactic Pole.
Colour selection is used to study the clustering of galaxies z=0 to z=0.4.
The galaxy correlation function is found to strongly depend on colour with red
galaxies more strongly clustered than blue galaxies by a factor of 5 at small
scales. The slope of the correlation function is also found to vary with colour
with gamma=1.8 for red galaxies while gamma=1.5 for blue galaxies. The
clustering of red galaxies is consistently strong over the entire magnitude
range studied though there are large variations between the two fields. The
clustering of blue galaxies is extremely weak over the observed magnitude range
with clustering consistent with r_0=2 Mpc. This is weaker than the clustering
of late-type galaxies in the local Universe and suggests galaxy clustering is
more strongly correlated with colour than morphology. This may also be the
first detection of a substantial low redshift galaxy population with clustering
properties similar to faint blue galaxies.Comment: Accepted for publication in MNRAS. 13 pages, 20 figure
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