196 research outputs found
Being relevant: Practical guidance for early career researchers interested in solving conservation problems
AbstractIn a human-altered world where biodiversity is in decline and conservation problems abound, there is a dire need to ensure that the next generation of conservation scientists have the knowledge, skills, and training to address these problems. So called āearly career researchersā (ECRs) in conservation science have many challenges before them and it is clear that the status quo must change to bridge the knowledgeāaction divide. Here we identify thirteen practical strategies that ECRs can employ to become more relevant. In this context, ārelevanceā refers to the ability to contribute to solving conservation problems through engagement with practitioners, policy makers, and stakeholders. Conservation and career strategies outlined in this article include the following: thinking ābig pictureā during conservation projects; embracing various forms of knowledge; maintaining positive relationships with locals familiar with the conservation issue; accepting failure as a viable (and potentially valuable) outcome; daring to be creative; embracing citizen science; incorporating interdisciplinarity; promoting and practicing pro-environmental behaviours; understanding financial aspects of conservation; forming collaboration from the onset of a project; accepting the limits of technology; ongoing and effective networking; and finally, maintaining a positive outlook by focusing on and sharing conservation success stories. These strategies move beyond the generic and highlight the importance of continuing to have an open mind throughout the entire conservation process, from establishing oneās self as an asset to embracing collaboration and interdisciplinary work, and striving to push for professional and personal connections that strengthen personal career objectives
The Importance of Time Congruity in the Organisation.
In 1991 Kaufman, Lane, and Lindquist proposed that time congruity in terms of an individual's time preferences and the time use methods of an organisation would lead to satisfactory performance and enhancement of quality of work and general life. The research reported here presents a study which uses commensurate person and job measures of time personality in an organisational setting to assess the effects of time congruity on one aspect of work life, job-related affective well-being. Results show that time personality and time congruity were found to have direct effects on well-being and the influence of time congruity was found to be mediated through time personality, thus contributing to the personājob (PāJ) fit literature which suggests that direct effects are often more important than indirect effects. The study also provides some practical examples of ways to address some of the previously cited methodological issues in PāJ fit research
The ALMA REBELS Survey: The First Infrared Luminosity Function Measurement at $\mathbf{z \sim 7}
We present the first observational infrared luminosity function (IRLF)
measurement in the Epoch of Reionization (EoR) based on a UV-selected galaxy
sample with ALMA spectroscopic observations. Our analysis is based on the ALMA
large program Reionization Era Bright Emission Line Survey (REBELS), which
targets 42 galaxies at with [CII] 158\micron line scans.
16 sources exhibit a dust detection, 15 of which are also spectroscopically
confirmed through the [CII] line. The IR luminosities of the sample range from
to 12.2. Using the UVLF as a proxy to derive the
effective volume for each of our target sources, we derive IRLF estimates, both
for detections and for the full sample including IR luminosity upper limits.
The resulting IRLFs are well reproduced by a Schechter function with the
characteristic luminosity of . Our
observational results are in broad agreement with the average of predicted
IRLFs from simulations at . Conversely, our IRLFs lie significantly
below lower redshift estimates, suggesting a rapid evolution from to
, into the reionization epoch. The inferred obscured contribution to
the cosmic star-formation rate density at amounts to
which is at
least 10\% of UV-based estimates. We conclude that the presence of dust
is already abundant in the EoR and discuss the possibility of unveiling larger
samples of dusty galaxies with future ALMA and JWST observations.Comment: 9 pages, 5 figure
The ALMA REBELS Survey: the first infrared luminosity function measurement at z ā¼ 7
We present the first observational infrared luminosity function (IRLF) measurement in the Epoch of Reionization (EoR) based on a ultraviolet (UV)-selected galaxy sample with the Atacama Large Millimeter Array (ALMA) spectroscopic observations. Our analysis is based on the ALMA large program Reionization Era Bright Emission Line Survey (REBELS), which targets 42 galaxies at z = 6.4ā7.7 with [CāII] 158 Ī¼m
line scans. 16 sources exhibit dust detection, 15 of which are also spectroscopically confirmed through the [CāII] line. The infrared (IR) luminosities of the sample range from logāLIR/Lā = 11.4 to 12.2. Using the UV luminosity function as a proxy to derive the effective volume for each of our target sources, we derive IRLF estimates, both for detections and for the full sample including IR luminosity upper limits. The resulting IRLFs are well reproduced by a Schechter function with the characteristic luminosity of logLā/Lā=11.6+0.2ā0.1
. Our observational results are in broad agreement with the average of predicted IRLFs from simulations at z ā¼ 7. Conversely, our IRLFs lie significantly below lower redshift estimates, suggesting a rapid evolution from z ā¼ 4 to z ā¼ 7, into the reionization epoch. The IR obscured contribution to the cosmic star formation rate density at z ā¼ 7 amounts to log(SFRD/Māyrā1Mpcā3)=ā2.66+0.17ā0.14
that is at least ā¼10 per cent of UV-based estimates. We conclude that the presence of dust is already abundant in the EoR and discuss the possibility of unveiling larger samples of dusty galaxies with future ALMA and JWST observations
Extremely deep 150 MHz source counts from the LoTSS Deep Fields
International audienceWith the advent of new generation low-frequency telescopes, such as the LOw Frequency ARray (LOFAR), and improved calibration techniques, we have now started to unveil the subgigahertz radio sky with unprecedented depth and sensitivity. The LOFAR Two Meter Sky Survey (LoTSS) is an ongoing project in which the whole northern radio sky will be observed at 150 MHz with a sensitivity better than 100 Ī¼Jy beamā1 at a resolution of 6ā²ā². Additionally, deeper observations are planned to cover smaller areas with higher sensitivity. The Lockman Hole, the Boƶtes, and the Elais-N1 regions are among the most well known northern extra-galactic fields and the deepest of the LoTSS Deep Fields so far. We exploited these deep observations to derive the deepest radio source counts at 150 MHz to date. Our counts are in broad agreement with those from the literature and show the well known upturn at ā¤1 mJy, mainly associated with the emergence of the star-forming galaxy population. More interestingly, our counts show, for the first time a very pronounced drop around S ~ 2 mJy, which results in a prominent ābumpā at sub-mJy flux densities. Such a feature was not observed in previous countsā determinations (neither at 150 MHz nor at a higher frequency). While sample variance can play a role in explaining the observed discrepancies, we believe this is mostly the result of a careful analysis aimed at deblending confused sources and removing spurious sources and artifacts from the radio catalogs. This ādrop and bumpā feature cannot be reproduced by any of the existing state-of-the-art evolutionary models, and it appears to be associated with a deficiency of active galactic nuclei (AGN) at an intermediate redshift (1 < z < 2) and an excess of low-redshift (z < 1) galaxies and/or AGN.Key words: galaxies: evolution / surveys / radio continuum: genera
The ALMA-ALPINE [CII] survey: Kennicutt-Schmidt relation in four massive main-sequence galaxies at <i>z</i> ā¼ 4.5
Aims. The Kennicutt-Schmidt (KS) relation between the gas and the star formation rate (SFR) surface density (Ī£ā
āā
Ī£) is essential to understand star formation processes in galaxies. To date, it has been measured up to z ā¼ 2.5 in main-sequence galaxies. In this Letter our aim is to put constraints at zāā¼ā4.5 using a sample of four massive main-sequence galaxies observed by ALMA at high resolution.
Methods. We obtained ā¼0.3ā³-resolution [CII] and continuum maps of our objects, which we then converted into gas and obscured SFR surface density maps. In addition, we produced unobscured SFR surface density maps by convolving Hubble ancillary data in the rest-frame UV. We then derived the average Ī£ in various Ī£ bins, and estimated the uncertainties using a Monte Carlo sampling.
Results. Our galaxy sample follows the KS relation measured in main-sequence galaxies at lower redshift, and is slightly lower than the predictions from simulations. Our data points probe the high end both in terms of Ī£ and Ī£, and gas depletion timescales (285ā843 Myr) remain similar to z ā¼ 2 objects. However, three of our objects are clearly morphologically disturbed, and we could have expected shorter gas depletion timescales (ā²100 Myr) similar to merger-driven starbursts at lower redshifts. This suggests that the mechanisms triggering starbursts at high redshift may be different than in the low- and intermediate-z Universe
The ALMA REBELS survey: the dust content of z ā¼7 Lyman break galaxies
We include a fully coupled treatment of metal and dust enrichment into the Delphi semi-analytic model of galaxy formation to explain the dust content of 13 Lyman break galaxies (LBGs) detected by the Atacama Large millimetre Array (ALMA) REBELS Large Program at z ā 7. We find that the galaxy dust mass, Md, is regulated by the combination of Type II supernova dust production, astration, shock destruction, and ejection in outflows; grain growth (with a standard time-scale Ļ0 = 30 Myr) plays a negligible role. The model predicts a dust-to-stellar mass ratio of ~ 0.07-0.1per cent and a UV-to-total star formation rate relation such that log(ĻUV) = -0.05 [log(Ļ)]2 + 0.86 log(Ļ) - 0.05 (implying that 55-80 per cent of the star formation is obscured) for REBELS galaxies with stellar mass Mā = 109-1010 Mā. This relation reconciles the intrinsic UV luminosity of LBGs with their observed luminosity function at z = 7. However, 2 out of the 13 systems show dust-to-stellar mass ratios (~0.94-1.1per cent) that are up to 18 times larger than expected from the fiducial relation. Due to the physical coupling between dust and metal enrichment, even decreasing Ļ0 to very low values (0.3 Myr) only increases the dust-to-stellar mass ratio by a factor of ā¼2. Given that grain growth is not a viable explanation for such high observed ratios of the dust-to-stellar mass, we propose alternative solutions
The ALMA REBELS survey: obscured star formation in massive Lyman-break galaxies at z = 4-8 revealed by the IRX- and relations
We investigate the degree of dust obscured star formation in 49 massive
() Lyman-break galaxies (LBGs) at
- observed as part of the ALMA Reionization Era Bright Emission
Line Survey (REBELS) large program. By creating deep stacks of the photometric
data and the REBELS ALMA measurements we determine the average rest-frame UV,
optical and far-infrared (FIR) properties which reveal a significant fraction
(-) of obscured star formation, consistent with
previous studies. From measurements of the rest-frame UV slope, we find that
the brightest LBGs at these redshifts show bluer () colours
than expected from an extrapolation of the colour-magnitude relation found at
fainter magnitudes. Assuming a modified blackbody spectral-energy distribution
(SED) in the FIR (with dust temperature of and
), we find that the REBELS sources are in agreement with
the local ''Calzetti-like'' starburst Infrared-excess (IRX)- relation.
By reanalysing the data available for 108 galaxies at - from the
ALPINE ALMA large program using a consistent methodology and assumed FIR SED,
we show that from -, massive galaxies selected in the rest-frame
UV have no appreciable evolution in their derived IRX- relation. When
comparing the IRX- relation derived from the combined ALPINE and
REBELS sample to relations established at , we find a deficit in the
IRX, indicating that at the proportion of obscured star formation is
lower by a factor of at a given a . Our IRX-
results are in good agreement with the high-redshift predictions of simulations
and semi-analytic models for galaxies with similar stellar masses
and SFRs.Comment: 18 pages, 10 figures, 2 tables (plus 1 figure and 2 tables in the
appendix). Updated to match MNRAS accepted version after minor correction
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