563 research outputs found
Long-Term Optical Monitoring of Eta Carinae. Multiband light curves for a complete orbital period
The periodicity of 5.5 years for some observational events occurring in Eta
Carinae manifests itself across a large wavelength range and has been
associated with its binary nature. These events are supposed to occur when the
binary components are close to periastron. To detect the previous periastron
passage of Eta Car in 2003, we started an intensive, ground-based, optical,
photometric observing campaign. We continued observing the object to monitor
its photometric behavior and variability across the entire orbital cycle. Our
observation program consisted of daily differential photometry from CCD images,
which were acquired using a 0.8 m telescope and a standard BVRI filter set at
La Plata Observatory. The photometry includes the central object and the
surrounding Homunculus nebula. We present up-to-date results of our observing
program, including homogeneous photometric data collected between 2003 and
2008. Our observations demonstrated that Eta Car has continued increasing in
brightness at a constant rate since 1998. In 2006, it reached its brightest
magnitude (V ~ 4.7) since about 1860s. The object then suddenly reverted its
brightening trend, fading to V = 5.0 at the beginning of 2007, and has
maintained a quite steady state since then. We continue the photometric
monitoring of Eta Car in anticipation of the next "periastron passage",
predicted to occur at the beginning of 2009.Comment: Accepted by A&A. The paper contains 3 figures and 2 table
Probing the atmosphere of HD189733b with the Na I and K I lines
High spectral resolution transmission spectroscopy is a powerful tool to
characterize exoplanet atmospheres. Especially for hot Jupiters, this technique
is highly relevant, due to their high altitude absorption e.g. from resonant
sodium (Na I) and potassium (K I) lines. We resolve the atmospheric K
I-absorption on HD189733b with the aim to compare the resolved K I -line and
previously obtained high resolution Na I-D-line observations with synthetic
transmission spectra. The line profiles suggest atmospheric processes leading
to a line broadening of the order of 10 km/s for the Na I-D-lines, and only a
few km/s for the K I-line. The investigation hints that either the atmosphere
of HD189733b lacks a significant amount of K I or the alkali lines probe
different atmospheric regions with different temperature, which could explain
the differences we see in the resolved absorption lines
The Factor Structure of Traumatic Stress in Parents of Children With Cancer: A Longitudinal Analysis*
ObjectivesâTo determine the factor structure of posttraumatic stress symptoms (PTSS) and assess its stability over time among parents of children diagnosed with cancer.âMethodsâParents of children with cancer included in a longitudinal study completed the posttraumatic stress disorder (PTSD) ChecklistâCivilian Version 2 weeks (nâ=â249) and 2 (nâ=â234) and 4 (nâ=â203) months after their child's diagnosis. Confirmatory factor analysis (CFA) was used to assess 3 models of the underlying dimensions of PTSD and invariance tests were used to assess stability over time.âResultsâA longitudinal CFA with the factors reexperiencing, avoidance, dysphoria, and hyperarousal provided best fit to the data. Invariance testing suggested that the pattern and size of loadings were equivalent across the three assessments.âDiscussionsâFindings tentatively suggest that PTSS among parents of children with cancer consist of four factors. Implications for research and clinical practice are discussed
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Health-related quality of life in Huntingtonâs Disease patients: a comparison of proxy assessment and patient self-rating using the disease-specific Huntingtonâs Disease health-related quality of life questionnaire (HDQoL)
Huntingtonâs disease (HD) is a fatal, neurodegenerative disease for which there is no known cure. Proxy evaluation is relevant for HD as its manifestation might limit the ability of persons to report their health-related quality of life (HrQoL). This study explored patientâproxy ratings of HrQoL of persons at different stages of HD, and examined factors that may affect proxy ratings. A total of 105 patientâproxy pairs completed the Huntingtonâs disease health-related quality of life questionnaire (HDQoL) and other established HrQoL measures (EQ-5D and SF-12v2). Proxyâpatient agreement was assessed in terms of absolute level (mean ratings) and intraclass correlation. Proxiesâ ratings were at a similar level to patientsâ self-ratings on an overall Summary Score and on most of the six Specific Scales of the HDQoL. On the Specific Hopes and Worries Scale, proxies on average rated HrQoL as better than patientsâ self-ratings, while on both the Specific Cognitive Scale and Specific Physical and Functional Scale proxies tended to rate HrQoL more poorly than patients themselves. The patientâs disease stage and mental wellbeing (SF-12 Mental Component scale) were the two factors that primarily affected proxy assessment. Proxy scores were strongly correlated with patientsâ self-ratings of HrQoL, on the Summary Scale and all Specific Scales. The patientâproxy correlation was lower for patients at moderate stages of HD compared to patients at early and advanced stages. The proxy report version of the HDQoL is a useful complementary tool to self-assessment, and a promising alternative when individual patients with advanced HD are unable to self-report
Weight Consistency Specifies Regularities of Macaque Cortical Networks
To what extent cortical pathways show significant weight differences and whether these differences are consistent across animals (thereby comprising robust connectivity profiles) is an important and unresolved neuroanatomical issue. Here we report a quantitative retrograde tracer analysis in the cynomolgus macaque monkey of the weight consistency of the afferents of cortical areas across brains via calculation of a weight index (fraction of labeled neurons, FLN). Injection in 8 cortical areas (3 occipital plus 5 in the other lobes) revealed a consistent pattern: small subcortical input (1.3% cumulative FLN), high local intrinsic connectivity (80% FLN), high-input form neighboring areas (15% cumulative FLN), and weak long-range corticocortical connectivity (3% cumulative FLN). Corticocortical FLN values of projections to areas V1, V2, and V4 showed heavy-tailed, lognormal distributions spanning 5 orders of magnitude that were consistent, demonstrating significant connectivity profiles. These results indicate that 1) connection weight heterogeneity plays an important role in determining cortical network specificity, 2) high investment in local projections highlights the importance of local processing, and 3) transmission of information across multiple hierarchy levels mainly involves pathways having low FLN values
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