Física y teoría del conocimiento.

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NEWTON, I.: Principios matemáticos de la filosofía natural.

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El ideal ilustrado de descripción de la Naturaleza a la luz del siglo XX.

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NEWTON, I.: Principios matemáticos de la filosofía natural.

Sin resume

Physical properties of high-mass clumps in different stages of evolution

(Abridged) Aims. To investigate the first stages of the process of high-mass star formation, we selected a sample of massive clumps previously observed with the SEST at 1.2 mm and with the ATNF ATCA at 1.3 cm. We want to characterize the physical conditions in such sources, and test whether their properties depend on the evolutionary stage of the clump. Methods. With ATCA we observed the selected sources in the NH3(1,1) and (2,2) transitions and in the 22 GHz H2O maser line. Ammonia lines are a good temperature probe that allow us to accurately determine the mass and the column-, volume-, and surface densities of the clumps. We also collected all data available to construct the spectral energy distribution of the individual clumps and to determine if star formation is already occurring, through observations of its most common signposts, thus putting constraints on the evolutionary stage of the source. We fitted the spectral energy distribution between 1.2 mm and 70 microns with a modified black body to derive the dust temperature and independently determine the mass. Results. The clumps are cold (T~10-30 K), massive (M~10^2-10^3 Mo), and dense (n(H2)>~10^5 cm^-3) and they have high column densities (N(H2)~10^23 cm^-2). All clumps appear to be potentially able to form high-mass stars. The most massive clumps appear to be gravitationally unstable, if the only sources of support against collapse are turbulence and thermal pressure, which possibly indicates that the magnetic field is important in stabilizing them. Conclusions. After investigating how the average properties depend on the evolutionary phase of the source, we find that the temperature and central density progressively increase with time. Sources likely hosting a ZAMS star show a steeper radial dependence of the volume density and tend to be more compact than starless clumps.Comment: Published in A&A, Vol. 556, A1

Física y teoría del conocimiento.

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Elderly day care centers: Recommendations for improvement

Indexación: Scopus.Introduction: Chile has become a country that continues to grow at an accelerated pace. One of the key pieces of the Comprehensive Policy for Positive Aging for Chile is the development of Day Centers for the Elderly (CDPM) directed elderly at the foot of the dependency. Objective: To know the perception of a group of PMs, their caregivers and professionals of their participation in the CDPM with the purpose of designing recommendations to improve this new type of geriatric service established in the country. Methodology: Qualitative descriptive study performed in 30 participants through 4 focus groups: 2 in elderly (n=12), 1 with caregivers (n=8) and 1 with center professionals (n=10). Results: Two main comprehensive categories were identified: 1) Perception of benefits for elderly: improvement of functionality, increase of well-being and insertion of the social mayor, 2) Recommendations for improvement of CDPM: Criteria for inclusive income, flexibility and diversity in activities stipulated and Improvements in egress. Conclusions: The elderly, their caregivers and the professionals who attend them are consistent in pointing out that elderly assistance to this type of service reports benefits in its functionality, well-being and social insertion. This study contributes to broadening the understanding of results in the uses of CDPM by reporting an experience in a particular social context. © 2018 Spanish Publishers Associate. All rights reserved.Introduction: Chile has become a country that continues to grow at an accelerated pace. One of the key pieces of the Comprehensive Policy for Positive Aging for Chile is the development of Day Centers for the Elderly (CDPM) directed elderly at the foot of the dependency. Objective: To know the perception of a group of PMs, their caregivers and professionals of their participation in the CDPM with the purpose of designing recommendations to improve this new type of geriatric service established in the country. Methodology: Qualitative descriptive study performed in 30 participants through 4 focus groups: 2 in elderly (n=12), 1 with caregivers (n=8) and 1 with center professionals (n=10). Results: Two main comprehensive categories were identified: 1) Perception of benefits for elderly: improvement of functionality, increase of well-being and insertion of the social mayor, 2) Recommendations for improvement of CDPM: Criteria for inclusive income, flexibility and diversity in activities stipulated and Improvements in egress. Conclusions: The elderly, their caregivers and the professionals who attend them are consistent in pointing out that elderly assistance to this type of service reports benefits in its functionality, well-being and social insertion. This study contributes to broadening the understanding of results in the uses of CDPM by reporting an experience in a particular social context.http://www.gerokomos.com/wp-content/uploads/2018/03/29-1-2018-009.pd

The Location of the Core in M81

We report on VLBI observations of M81*, the northwest-southeast oriented nuclear core-jet source of the spiral galaxy M81, at five different frequencies between 1.7 and 14.8 GHz. By phase referencing to supernova 1993J we can accurately locate the emission region of M81* in the galaxy's reference frame. Although the emission region's size decreases with increasing frequency while the brightness peak moves to the southwest, the emission region seems sharply bounded to the southwest at all frequencies. We argue that the core must be located between the brightness peak at our highest frequency (14.8 GHz) and the sharp bound to the southwest. This narrowly constrains the location of the core, or the purported black hole in the center of the galaxy, to be within a region of +/-0.2 mas or +/-800 AU (at a distance of ~4 Mpc). This range includes the core position that we determined earlier by finding the most stationary point in the brightness distribution of M81* at only a single frequency. This independent constraint therefore strongly confirms our earlier core position. Our observations also confirm that M81* is a core-jet source, with a one-sided jet that extends to the northeast from the core, on average curved somewhat to the east, with a radio spectrum that is flat or inverted near the core and steep at the distant end. The brightness peak is unambiguously identified with the variable jet rather than the core, which indicates limitations in determining the proper motion of nearby galaxies and in refining the extragalactic reference frame.Comment: LaTeX, 10 pages with 3 figures. Typos fixed and slight rewording for clarity from previous version. Accepted for publication in the Astrophysical Journa