Insights on star formation histories and physical properties of 1.2≤z≲41.2 \leq z \lesssim 4 Herschel-detected galaxies

We test the impact of using variable star forming histories (SFHs) and the use of the IR luminosity (LIR) as a constrain on the physical parameters of high redshift dusty star-forming galaxies. We explore in particular the stellar properties of galaxies in relation with their location on the SFR-M* diagram. We perform SED fitting of the UV-NIR and FIR emissions of a large sample of GOODS-Herschel galaxies, for which rich multi-wavelength observations are available. We test different SFHs and imposing energy conservation in the SED fitting process, to face issues like the age-extinction degeneracy and produce SEDs consistent with observations. Our models work well for the majority of the sample, with the notable exception of the high LIR end, for which we have indications that our simple energy conservation approach cannot hold true. We find trends in the SFHs fitting our sources depending on stellar mass M* and z. Trends also emerge in the characteristic timescales of the SED models depending on the location on the SFR-M* diagram. We show that whilst using the same available observational data, we can produce galaxies less star-forming than usually inferred, if we allow declining SFHs, while properly reproducing their observables. These sources can be post-starbursts undergoing quenching, and their SFRs are potentially overestimated if inferred from their LIR. Fitting without the IR constrain leads to a strong preference for declining SFHs, while its inclusion increases the preference of rising SFHs, more so at high z, in tentative agreement with the cosmic star formation history. Keeping in mind that the sample is biased towards high LIR, the evolution shaped by our model appears as both bursty (initially) and steady-lasting (later on). The global SFH of the sample follows the cosmic SFH with a small scatter, and is compatible with the "downsizing" scenario of galaxy evolution.Comment: 28 pages, 26 figures, one appendix, Accepted for publication in Astronomy & Astrophysic

ALMA detection of [CII] 158 micron emission from a strongly lensed z=2 star-forming galaxy

Our objectives are to determine the properties of the interstellar medium (ISM) and of star-formation in typical star-forming galaxies at high redshift. Following up on our previous multi-wavelength observations with HST, Spitzer, Herschel, and the Plateau de Bure Interferometer (PdBI), we have studied a strongly lensed z=2.013 galaxy, the arc behind the galaxy cluster MACS J0451+0006, with ALMA to measure the [CII] 158 micron emission line, one of the main coolants of the ISM. [CII] emission from the southern part of this galaxy is detected at 10 $\sigma$. Taking into account strong gravitational lensing, which provides a magnification of $\mu=49$, the intrinsic lensing-corrected [CII]158 micron luminosity is $L(CII)=1.2 \times 10^8 L_\odot$. The observed ratio of [CII]-to-IR emission, $L(CII)/L(FIR) \approx (1.2-2.4) \times 10^{-3}$, is found to be similar to that in nearby galaxies. The same also holds for the observed ratio $L(CII)/L(CO)=2.3 \times 10^3$, which is comparable to that of star-forming galaxies and active galaxy nuclei (AGN) at low redshift. We utilize strong gravitational lensing to extend diagnostic studies of the cold ISM to an order of magnitude lower luminosity ($L(IR) \sim (1.1-1.3) \times 10^{11} L_\odot$) and SFR than previous work at high redshift. While larger samples are needed, our results provide evidence that the cold ISM of typical high redshift galaxies has physical characteristics similar to normal star forming galaxies in the local Universe.Comment: 5 pages, 4 figures. Accepted for publication in Astronomy & Astrophysics, Letter

DNA methylome analysis identifies accelerated epigenetic aging associated with postmenopausal breast cancer susceptibility

Aim of the study A vast majority of human malignancies are associated with ageing, and age is a strong predictor of cancer risk. Recently, DNA methylation-based marker of ageing, known as ‘epigenetic clock’, has been linked with cancer risk factors. This study aimed to evaluate whether the epigenetic clock is associated with breast cancer risk susceptibility and to identify potential epigenetics-based biomarkers for risk stratification. Methods Here, we profiled DNA methylation changes in a nested case–control study embedded in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort (n = 960) using the Illumina HumanMethylation 450K BeadChip arrays and used the Horvath age estimation method to calculate epigenetic age for these samples. Intrinsic epigenetic age acceleration (IEAA) was estimated as the residuals by regressing epigenetic age on chronological age. Results We observed an association between IEAA and breast cancer risk (OR, 1.04; 95% CI, 1.007–1.076, P = 0.016). One unit increase in IEAA was associated with a 4% increased odds of developing breast cancer (OR, 1.04; 95% CI, 1.007–1.076). Stratified analysis based on menopausal status revealed that IEAA was associated with development of postmenopausal breast cancers (OR, 1.07; 95% CI, 1.020–1.11, P = 0.003). In addition, methylome-wide analyses revealed that a higher mean DNA methylation at cytosine-phosphate-guanine (CpG) islands was associated with increased risk of breast cancer development (OR per 1 SD = 1.20; 95 %CI: 1.03–1.40, P = 0.02) whereas mean methylation levels at non-island CpGs were indistinguishable between cancer cases and controls. Conclusion Epigenetic age acceleration and CpG island methylation have a weak, but statistically significant, association with breast cancer susceptibility

Properties of z~3-6 Lyman break galaxies. II. Testing star formation histories and the SFR-mass relation with ALMA and near-IR spectroscopy

We examine the dependence of derived physical parameters of distant Lyman break galaxies (LBGs) on the assumed star formation histories (SFHs), their implications on the SFR-mass relation, and we propose observational tests to better constrain these quantities. We use our SED-fitting tool including nebular emission to analyze a large sample of LBGs, assuming five different star formation histories, extending our first analysis of this sample (de Barros et al. 2012, paper I). In addition we predict the IR luminosities consistently with the SED fits. Compared to "standard" SED fits assuming constant SFR and neglecting nebular lines, assuming variable SFHs yield systematically lower stellar masses, higher extinction, higher SFR, higher IR luminosities, and a wider range of equivalent widths for optical emission lines. Exponentially declining and delayed SFHs yield basically identical results and generally fit best. Exponentially rising SFHs yield similar masses, but somewhat higher extinction. We find significant deviations between the derived SFR and IR luminosity from the commonly used SFR(IR) or SFR(IR+UV) calibration, due to differences in the SFHs and ages. Models with variable SFHs, favored statistically, yield generally a large scatter in the SFR-mass relation. We show that the true scatter in the SFR-mass relation can be significantly larger than inferred using SFR(UV) and/or SFR(IR). Different SFHs, and hence differences in the derived SFR-mass relation and in the specific star formation rates, can be tested/constrained observationally with future IR observations with ALMA. Measurement of emission lines, such as Halpha and [OII]3727, can also provide useful constraints on the SED models. We conclude that our findings of a large scatter in SFR-mass at high-z and an increase of the specific star formation rate above z>~3 (paper I) can be tested observationally. (abriged)Comment: 20 pages, 27 figures included, revised version, accepted for publication in Astronomy and Astrophysic

Properties of z∼3−6z\sim3-6 Lyman Break Galaxies. II. Impact of nebular emission at high redshift

We present a homogeneous, detailed analysis of the spectral energy distribution (SED) of $\sim$ 1700 LBGs from the GOODS-MUSIC catalogue with deep multi-wavelength photometry from $U$ band to 8 $\mu$m to determine stellar mass, age, dust attenuation, and star formation rate. Using our SED fitting tool, which takes into account nebular emission, we explore a wide parameter space. We also explore a set of different star formation histories. Nebular emission is found to significantly affect the determination of the physical parameters for the majority of $z \sim$ 3--6 LBGs. We identify two populations of galaxies by determining the importance of the contribution of emission lines to broadband fluxes. We find that $\sim$ $65\%$ of LBGs show detectable signs of emission lines, whereas $\sim$ $35\%$ show weak or no emission lines. This distribution is found over the entire redshift range. We interpret these groups as actively star forming and more quiescent LBGs, respectively. We find that it is necessary to considerer SED fits with very young ages ($<50$ Myr) to reproduce some colours affected by strong emission lines. Other arguments favouring episodic star formation and relatively short star formation timescales are also discussed. Considering nebular emission generally leads to a younger age, lower stellar mass, higher dust attenuation, higher star formation rate, and a large scatter in the SFR-$M_{\star}$ relation. Our analysis yields a trend of increasing specific star formation rate with redshift, as predicted by recent galaxy evolution models. The physical parameters of approximately two thirds of high redshift galaxies are significantly modified when we account for nebular emission. The SED models which include nebular emission shed new light on the properties of LBGs with numerous important implications.Comment: 33 pages, 30 figures, 5 tables, extended version addressing referee comments, conclusions unchanged, accepted for publication in A&A, in pres

Roadmap for investigating epigenome deregulation and environmental origins of cancer: Epigenetics and cancer

The interaction between the (epi)genetic makeup of an individual and his/her environmental exposure record (exposome) is accepted as a determinant factor for a significant proportion of human malignancies. Recent evidence has highlighted the key role of epigenetic mechanisms in mediating gene–environment interactions and translating exposures into tumorigenesis. There is also growing evidence that epigenetic changes may be risk factor‐specific (“fingerprints”) that should prove instrumental in the discovery of new biomarkers in cancer. Here, we review the state of the science of epigenetics associated with environmental stimuli and cancer risk, highlighting key developments in the field. Critical knowledge gaps and research needs are discussed and advances in epigenomics that may help in understanding the functional relevance of epigenetic alterations. Key elements required for causality inferences linking epigenetic changes to exposure and cancer are discussed and how these alterations can be incorporated in carcinogen evaluation and in understanding mechanisms underlying epigenome deregulation by the environment

Roadmap for investigating epigenome deregulation and environmental origins of cancer.

The interaction between the (epi)genetic makeup of an individual and his/her environmental exposure record (exposome) is accepted as a determinant factor for a significant proportion of human malignancies. Recent evidence has highlighted the key role of epigenetic mechanisms in mediating gene-environment interactions and translating exposures into tumorigenesis. There is also growing evidence that epigenetic changes may be risk factor-specific ('fingerprints') that should prove instrumental in the discovery of new biomarkers in cancer. Here, we review the state of the science of epigenetics associated with environmental stimuli and cancer risk, highlighting key developments in the field. Critical knowledge gaps and research needs are discussed as well as advances in epigenomics that may help an understanding of the functional relevance of epigenetic alterations. Key elements required for causality inferences linking epigenetic changes to exposure and cancer are discussed as well as how these alterations can be incorporated in carcinogen evaluation and in understanding mechanisms underlying epigenome deregulation by the environment

The political economy of the Greek economic crisis in 2020

In this article, we emphasize the political causes of the crisis in order to evaluate not only whether these have been the main factors behind the economic crisis (particularly over the last decade), but also whether these can be considered the main factors for the failure of Greek and European officials to overcome the economic crisis. Over the last ten years, there has been something of a deterioration of the political variables and we are now faced with a question of whether we can begin to talk about a way out of the crisis. As per our argument, despite the acceptance of new institutional rules for the efficient operation of the economy through the memoranda of understanding, Greece’s performance has worsened in terms of its political and institutional governance indicators over the last decades. This fact is particularly worrying because it highlights an overall failure to change the political conditions that affect the overall quality of life and prosperity. © 2021 Informa UK Limited, trading as Taylor &amp; Francis Group