565 research outputs found
Water use efficiency and climate legacies dominate beech growth at its rear edge
Rear-edge
tree populations are experiencing a combination of higher temperatures
and more intense droughts that might push individuals beyond their tolerance
limits. This trend towards rising atmospheric [CO2] is concurrent with an
increase in intrinsic water use efficiency (iWUE), which theoretically enhances
photosynthesis and decrease evapotranspiration rates, consequently improving
tree resistance to drought. However, it remains unclear whether iWUE is favouring
tree growth under current climate conditions, particularly when climate and
iWUE legacy effects are simultaneously considered.
2. We evaluated this question with an extensive sampling along Iberian rear-edge
(dry) populations comprising four mountain ranges and two distinct altitudes. We
simultaneously examined the effects of climate and iWUE on secondary growth
using annually resolved basal area increments (BAIs) for the period 1901–2017.
We used linear mixed models including second-order
autocorrelation and 1-year
legacy effects of iWUE and summer drought.
3. BAI and iWUE increased across the studied period. iWUE increase was driven
by changes in atmospheric CO2 concentration and water availability during the
growing season. Climate and iWUE exerted direct and lagged effects on beech
growth. Water availability during growing season was the main driver of tree
growth, combining direct and indirect effects through its impact on iWUE. Legacy
effects of water availability and iWUE were more important than growing season
conditions. The net effect of iWUE shifted when lagged effects were considered,
resulting in a net negative impact on tree growth.
4. Synthesis: Our results reveal that climate and iWUE legacy effects must be considered
to assess the net iWUE effect on secondary growth. Considering lagged
effects, the current increase in iWUE is constraining tree growth. Modelling efforts
of tree growth response to climate warming should include climate and
iWUE legacy effects to adequately assess terrestrial ecosystem carbon balanceEU Feder Funds; EU LIFE, Grant/Award
NumberLIFE Soria Forest Adapt [LIFE19
CCA/ES/001181Junta de Castilla y
León-Consejería
de Educación, Grant/
Award Number: IR2020-1-
UVA08;
VA171P20Spanish Ministry for Science
and Innovation, Grant/Award Number:
LAUREL PID2019-109906RA-
I00
MCIN/AEI/10.13039/5011PROWARM
PID2020-118444GA-
100
MCIN/
AEI/10.13039/50Postdoctoral
grant IJC2019-040571-
I
MCIN/
AEI/10.13Predoctoral grant
PRE2018-084106
funded by MCIN/AEspRING CGL2017-87309-
P
MCIN/
AEI/10.13039/50110001
The nature of the dense core population in the Pipe Nebula: A survey of NH3, CCS, and HC5N molecular line emission
Recent extinction studies of the Pipe Nebula (d=130 pc) reveal many cores
spanning a range in mass from 0.2 to 20.4 Msun. These dense cores were
identified via their high extinction and comprise a starless population in a
very early stage of development. Here we present a survey of NH3 (1,1), NH3
(2,2), CCS (2_1,1_0), and HC5N (9,8) emission toward 46 of these cores. An
atlas of the 2MASS extinction maps is also presented. In total, we detect 63%
of the cores in NH3 (1,1) 22% in NH3 (2,2), 28% in CCS, and 9% in HC5N
emission. We find the cores are associated with dense gas (~10^4 cm-3) with 9.5
< T_k < 17 K. Compared to C18O, we find the NH3 linewidths are systematically
narrower, implying that the NH3 is tracing the dense component of the gas and
that these cores are relatively quiescent. We find no correlation between core
linewidth and size. The derived properties of the Pipe cores are similar to
cores within other low-mass star-forming regions: the only differences are that
the Pipe cores have weaker NH3 emision and most show no current star formation
as evidenced by the lack of embedded infrared sources. Such weak NH3 emission
could arise due to low column densities and abundances or reduced excitation
due to relatively low core volume densities. Either alternative implies that
the cores are relatively young. Thus, the Pipe cores represent an excellent
sample of dense cores in which to study the initial conditions for star
formation and the earliest stages of core formation and evolution.Comment: 35 pages, 10 figures (excluding the appendix). For the complete
appendix contact [email protected]. Accepted for publication in ApJ
Detection of HC11N in the Cold Dust Cloud TMC-1
Two consecutive rotational transitions of the long cyanopolyyne HC11N,
J=39-38, and J=38-37, have been detected in the cold dust cloud TMC-1 at the
frequencies expected from recent laboratory measurements by Travers et al.
(1996), and at about the expected intensities. The astronomical lines have a
mean radial velocity of 5.8(1) km/s, in good agreement with the shorter
cyanopolyynes HC7N and HC9N observed in this very sharp-lined source [5.82(5)
and 5.83(5) km/s, respectively]. The column density of HC11N is calculated to
be 2.8x10^(11) cm^(-2). The abundance of the cyanopolyynes decreases smoothly
with length to HC11N, the decrement from one to the next being about 6 for the
longer carbon chains.Comment: plain tex 10 pages plus 3 ps fig file
Triggered Star Formation by Massive Stars
We present our diagnosis of the role that massive stars play in the formation
of low- and intermediate-mass stars in OB associations (the Lambda Ori region,
Ori OB1, and Lac OB1 associations). We find that the classical T Tauri stars
and Herbig Ae/Be stars tend to line up between luminous O stars and
bright-rimmed or comet-shaped clouds; the closer to a cloud the progressively
younger they are. Our positional and chronological study lends support to the
validity of the radiation-driven implosion mechanism, where the Lyman continuum
photons from a luminous O star create expanding ionization fronts to evaporate
and compress nearby clouds into bright-rimmed or comet-shaped clouds. Implosive
pressure then causes dense clumps to collapse, prompting the formation of
low-mass stars on the cloud surface (i.e., the bright rim) and
intermediate-mass stars somewhat deeper in the cloud. These stars are a
signpost of current star formation; no young stars are seen leading the
ionization fronts further into the cloud. Young stars in bright-rimmed or
comet-shaped clouds are likely to have been formed by triggering, which would
result in an age spread of several megayears between the member stars or star
groups formed in the sequence.Comment: 2007, ApJ, 657, 88
Interventions on the social dimension of people with chronic heart failure: a systematic review of randomized controlled trials
Aims
The symptom burden of patients with chronic heart failure (CHF), together with social determinants and psychosocial factors, results in limitations to maintain adequate social life and roles, participate in social events and maintain relationships. This situation's impact on health outcomes makes it of utmost importance to develop meaningful social networks for these patients. The primary objective aimed to identify randomized controlled trials that impact the social dimension of people with CHF. The secondary objectives were to analyze the methodological quality of these interventions, establish their components, and synthesize their results.
Methods and results
A systematic review following PRISMA guidelines was conducted in Pubmed, Scopus, Cochrane CENTRAL, PsychINFO, and CINAHL databases between 2010 and February 2022. The Revised Cochrane risk-of-bias tool for randomized trials was used. The protocol was registered in PROSPERO. Eight randomized controlled trials were identified, among which two were at ‘high risk of bias.’ Interventions were synthesized according to the following categories: delivery format, providers and recipients, and the intervention content domains. Half of the studies showed statistical superiority in improving the intervention group's social support in people with CHF.
Conclusion
This review has highlighted the scarcity of interventions targeting the social dimension of people with CHF. Interventions have been heterogeneous, which limits the statistical combination of studies. Based on narrative review and vote counting, such interventions could potentially improve social support and self-care, which are important patient reported outcomes, thus warrant further research. Future studies should be co-created with patients and families to be adequately targeted
Experiencing the possibility of near death on a daily basis: A phenomenological study of patients with chronic heart failure
Background: Chronic heart failure (CHF) is a syndrome that greatly impacts people’s lives. Due to the poor
prognosis of CHF, together with the frequent exacerbations of symptoms, death is a topic that is very present
in the lives of patients with CHF.
Objective: To explore thoughts about death experienced by patients with chronic heart failure in their daily lives.
Methods: A hermeneutic phenomenological study was carried out. Conversational interviews were conducted with 20 outpatients with chronic heart failure. Analysis of the responses was based on the method
proposed by van Manen.
Results: From the analysis, four main themes emerged: (1) Feeling afraid of the possibility of dying; (2) Acceptance of the possibility of death; (3) Desiring death for relief from suffering; and (4) Striving to continue living to enjoy family.
Conclusions: This study presents, as a novel finding, that people with CHF experience the possibility of near
death on a daily basis. This experience, which they must encounter on their own, makes them afraid. In addition, some of them, in view of the discomfort they are living, wish to die, with some even considering committing suicide
Formation scenarios for the young stellar associations between galactic longitudes l = 280-360 deg
We investigate the spatial distribution, the space velocities and age
distribution of the pre-main sequence (PMS) stars belonging to Ophiuchus, Lupus
and Chamaeleon star-forming regions (SFRs), and of the young early-type star
members of the Scorpius-Centaurus OB association. These young stellar
associations extend over the galactic longitude range from 280 deg. to 360
deg., and are at a distance interval of around 100 and 200 pc. This study is
based on a compilation of distances, proper motions and radial velocities from
the literature for the kinematic properties, and of basic stellar data for the
construction of Hertzsprung-Russel diagrams. Although there was no well-known
OB association in Chamaeleon, the distances and the proper motions of a group
of 21 B- and A-type stars, taken from the Hipparcos Catalogue, lead us to
propose that they form a young association. We show that the young early-type
stars of the OB associations and the PMS stars of the SFRs follow a similar
spatial distribution, i.e., there is no separation between the low and the
high-mass young stars. We find no difference in the kinematics nor in the ages
of these two populations studied. We analyze the different scenarios for the
triggering of large-scale star-formation that have been proposed up to now, and
argue that most probably we are observing a spiral arm that passes close to the
Sun. The alignment of young stars and molecular clouds and the average velocity
of the stars in the opposite direction to the Galactic rotation agree with the
expected behavior of star formation in nearby spiral arms.Comment: 14 pages, 14 postscript figures, accepted for publication in A&
The Distance to the Isolated Neutron Star RX J0720.4-3125
We have used a set of dedicated astrometric data from the Hubble Space
Telescope to measure the parallax and proper motion of the nearby neutron star
RX J0720.4-3125. At each of eight epochs over two years, we used the High
Resolution Camera of the Advanced Camera for Surveys to measure the position of
the B=26.6 target to a precision of ~2 mas (~0.07 pix) relative to 22 other
stars. From these data we measure a parallax of pi=2.8+/-0.9 mas (for a
distance of 360+170-90 pc) and a proper motion of mu=107.8+/-1.2 mas/yr.
Exhaustive testing of every stage of our analysis suggests that it is robust,
with a maximum systematic uncertainty on the parallax of 0.4 mas. The distance
is compatible with earlier estimates made from scaling the optical emission of
RX J0720.4-3125 relative to the even closer neutron star RX J1856.5-3754. The
distance and proper motion imply a transverse velocity of 180+90-40 km/s,
comparable to velocities observed for radio pulsars. The speed and direction
suggest an origin for RX J0720.4-3125 in the Trumpler 10 OB association ~0.7
Myr ago, with a possible range of 0.5-1.0 Myr given by the uncertainty in the
distance.Comment: 17 pages, 8 figures. To be published in Ap
Some cultural consequences in Spain of the Spanish Invasion of Morocco 1859-60
This article argues is a contribution to the study of interrelationships between colonialism, art, and literature in the nineteenth century. The article argues that the Spanish invasion of Morocco in 1859 led to contradictions and tensions within liberal nationalism, not least because of concerns about the tensions between the need for military reassertion of Spain and the respect for the independence of nations. This led to some reconfiguration of Spanish intellectuals' already complex relationship with North Africa and Islam. A major, perhaps surprising consequence of this reconfiguration, was some equation of Moroccan identity with a monotonous surface that was resistant to the gaze. In consequence, the Catalan painter Fortuny's crucial experience of Morocco led him to value near blank surfaces, and thus to make a major contribution to the origins of modern art
Mast cell-related disorders presenting with Kounis syndrome
Letter to the Editor.-- et al.Peer Reviewe
- …