With the recent discovery of a dozen dusty star-forming galaxies and around 30 quasars at z > 5 that are hyper-luminous in the infrared (μ LIR > 1013 L⊙, where μ is a lensing magnification factor), the possibility has opened up for SPICA, the proposed ESA M5 mid-/far-infrared mission, to extend its spectroscopic studies toward the epoch of reionisation and beyond. In this paper, we examine the feasibility and scientific potential of such observations with SPICA’s far-infrared spectrometer SAFARI, which will probe a spectral range (35–230 μm) that will be unexplored by ALMA and JWST. Our simulations show that SAFARI is capable of delivering good-quality spectra for hyper-luminous infrared galaxies at z = 5 − 10, allowing us to sample spectral features in the rest-frame mid-infrared and to investigate a host of key scientific issues, such as the relative importance of star formation versus AGN, the hardness of the radiation field, the level of chemical enrichment, and the properties of the molecular gas. From a broader perspective, SAFARI offers the potential to open up a new frontier in the study of the early Universe, providing access to uniquely powerful spectral features for probing first-generation objects, such as the key cooling lines of low-metallicity or metal-free forming galaxies (fine-structure and H2 lines) and emission features of solid compounds freshly synthesised by Population III supernovae. Ultimately, SAFARI’s ability to explore the high-redshift Universe will be determined by the availability of sufficiently bright targets (whether intrinsically luminous or gravitationally lensed). With its launch expected around 2030, SPICA is ideally positioned to take full advantage of upcoming wide-field surveys such as LSST, SKA, Euclid, and WFIRST, which are likely to provide extraordinary targets for SAFARI.

Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.

SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.

SPICA instruments offer spectral resolving power ranging from R ~50 through 11 000 in the 17–230 μm domain and R ~28.000 spectroscopy between 12 and 18 μm. SPICA will provide efficient 30–37 μm broad band mapping, and small field spectroscopic and polarimetric imaging at 100, 200 and 350 μm. SPICA will provide infrared spectroscopy with an unprecedented sensitivity of ~5 × 10−20 W m−2 (5σ/1 h)—over two orders of magnitude improvement over what earlier missions. This exceptional performance leap, will open entirely new domains in infrared astronomy; galaxy evolution and metal production over cosmic time, dust formation and evolution from very early epochs onwards, the formation history of planetary systems.

Excavations at several locations in Verteba Cave have uncovered a large amount of human skeletal remains in association with faunal bones and Tripolye material culture. We aim to establish radiocarbon (14C) dates for eight sites and to evaluate whether these deposits are singular events, or slow accumulations over time. 14C measurements, along with stable carbon and nitrogen isotope data from human and faunal remains, were collected from 18 specimens. Stable isotope values were used to evaluate human and animal diet, and whether freshwater reservoir effects offset measured dates. We found diets of the sampled species had limited to no influence from freshwater resources. Human diet appears to be dominated by terrestrial plants and herbivores. Four new sites were identified as Eneolithic. Comparisons of dates from top and bottom strata for two sites (7 and 20) reveal coeval dates, and we suggest that these deposits represent discrete events rather than slow continuous use. Lastly, we identified dates from the Mesolithic (8490±45 BP, 8765±30 BP), Iron Age (2505±20 BP), Slavic state era (1315±25 BP), and Medieval Period (585±15 BP), demonstrating periodic use of the cave by humans prior to and after the Eneolithic.

The SPICA mid- and far-infrared telescope will address fundamental issues in our understanding of star formation and ISM physics in galaxies. A particular hallmark of SPICA is the outstanding sensitivity enabled by the cold telescope, optimised detectors, and wide instantaneous bandwidth throughout the mid- and far-infrared. The spectroscopic, imaging, and polarimetric observations that SPICA will be able to collect will help in clarifying the complex physical mechanisms which underlie the baryon cycle of galaxies. In particular, (i) the access to a large suite of atomic and ionic fine-structure lines for large samples of galaxies will shed light on the origin of the observed spread in star-formation rates within and between galaxies, (ii) observations of HD rotational lines (out to ~10 Mpc) and fine structure lines such as [C ii] 158 μm (out to ~100 Mpc) will clarify the main reservoirs of interstellar matter in galaxies, including phases where CO does not emit, (iii) far-infrared spectroscopy of dust and ice features will address uncertainties in the mass and composition of dust in galaxies, and the contributions of supernovae to the interstellar dust budget will be quantified by photometry and monitoring of supernova remnants in nearby galaxies, (iv) observations of far-infrared cooling lines such as [O i] 63 μm from star-forming molecular clouds in our Galaxy will evaluate the importance of shocks to dissipate turbulent energy. The paper concludes with requirements for the telescope and instruments, and recommendations for the observing strategy.

IR spectroscopy in the range 12–230 μm with the SPace IR telescope for Cosmology and Astrophysics (SPICA) will reveal the physical processes governing the formation and evolution of galaxies and black holes through cosmic time, bridging the gap between the James Webb Space Telescope and the upcoming Extremely Large Telescopes at shorter wavelengths and the Atacama Large Millimeter Array at longer wavelengths. The SPICA, with its 2.5-m telescope actively cooled to below 8 K, will obtain the first spectroscopic determination, in the mid-IR rest-frame, of both the star-formation rate and black hole accretion rate histories of galaxies, reaching lookback times of 12 Gyr, for large statistically significant samples. Densities, temperatures, radiation fields, and gas-phase metallicities will be measured in dust-obscured galaxies and active galactic nuclei, sampling a large range in mass and luminosity, from faint local dwarf galaxies to luminous quasars in the distant Universe. Active galactic nuclei and starburst feedback and feeding mechanisms in distant galaxies will be uncovered through detailed measurements of molecular and atomic line profiles. The SPICA’s large-area deep spectrophotometric surveys will provide mid-IR spectra and continuum fluxes for unbiased samples of tens of thousands of galaxies, out to redshifts of z ~ 6.

The physical processes driving the chemical evolution of galaxies in the last ~ 11Gyr cannot be understood without directly probing the dust-obscured phase of star-forming galaxies and active galactic nuclei. This phase, hidden to optical tracers, represents the bulk of the star formation and black hole accretion activity in galaxies at 1 < z < 3. Spectroscopic observations with a cryogenic infrared observatory like SPICA, will be sensitive enough to peer through the dust-obscured regions of galaxies and access the rest-frame mid- to far-infrared range in galaxies at high-z. This wavelength range contains a unique suite of spectral lines and dust features that serve as proxies for the abundances of heavy elements and the dust composition, providing tracers with a feeble response to both extinction and temperature. In this work, we investigate how SPICA observations could be exploited to understand key aspects in the chemical evolution of galaxies: the assembly of nearby galaxies based on the spatial distribution of heavy element abundances, the global content of metals in galaxies reaching the knee of the luminosity function up to z ~ 3, and the dust composition of galaxies at high-z. Possible synergies with facilities available in the late 2020s are also discussed.

Background. This paper examines genetic and environmental contributions to risk of cannabis dependence.

Method. Symptoms of cannabis dependence and measures of social, family and individual risk factors were assessed in a sample of 6265 young adult male and female Australian twins born 1964–1971.

Results. Symptoms of cannabis dependence were common: 11·0% of sample (15·1% of men and 7·8% of women) reported two or more symptoms of dependence. Correlates of cannabis dependence included educational attainment, exposure to parental conflict, sexual abuse, major depression, social anxiety and childhood conduct disorder. However, even after control for the effects of these factors, there was evidence of significant genetic effects on risk of cannabis dependence. Standard genetic modelling indicated that 44·7% (95% CI = 15–72·2) of the variance in liability to cannabis dependence could be accounted for by genetic factors, 20·1% (95% CI = 0–43·6) could be attributed to shared environment factors and 35·3% (95% CI = 26·4–45·7) could be attributed to non-shared environmental factors. However, while there was no evidence of significant gender differences in the magnitude of genetic and environmental influences, a model which assumed both genetic and shared environmental influences on risks of cannabis dependence among men and shared environmental but no genetic influences among women provided an equally good fit to the data.

Conclusions. There was consistent evidence that genetic risk factors are important determinants of risk of cannabis dependence among men. However, it remains uncertain whether there are genetic influences on liability to cannabis dependence among women.

Bioarchaeological studies have found that, in general, the adoption of agriculture is associated with deteriorating oral health, most frequently manifested as an increase in the prevalence of dental caries. However, compared to other regions of the world, bioarchaeological studies focusing on prehistoric Europe have produced more variable results, with different populations experiencing deteriorations, improvements, and stasis in oral health. This study assesses the oral health of individuals of the Tripolye culture buried in Verteba Cave, Ukraine, within the context of the transition to agriculture in Eastern Europe. We compare the rates of dental caries between Tripolye farmers with earlier hunter-fisher-gatherers from Ukraine. The Tripolye were found to have carious lesions on 9.5 per cent of teeth, while the hunter-fisher-gatherers were found to be universally free of carious lesions. A Fisher's exact test demonstrates that this difference is statistically significant, supporting the model that the transition to agriculture was detrimental to oral health in prehistoric Ukraine. This could be related to the manner in which grain was processed by the Tripolye and the needs of their relatively population-dense society.

The aim of the present study was to determine whether age and sex influence both the status and incorporation of EPA and DHA into blood plasma, cells and tissues. The study was a double-blind, randomised, controlled intervention trial, providing EPA plus DHA equivalent to 0, 1, 2 or 4 portions of oily fish per week for 12 months. The participants were stratified by age and sex. A linear regression model was used to analyse baseline outcomes, with covariates for age or sex groups and by adjusting for BMI. The change in outcomes from baseline to 12 months was analysed with additional adjustment for treatment and average compliance. Fatty acid profiles in plasma phosphatidylcholine, cholesteryl esters, NEFA and TAG, mononuclear cells (MNC), erythrocyte membranes, platelets, buccal cells (BU) and adipose tissue (AT) were determined. At baseline, EPA concentrations in plasma NEFA and DHA concentrations in MNC, BU and AT were higher in females than in males (all P< 0·05). The concentrations of EPA in AT (P= 0·003) and those of DHA in plasma TAG (P< 0·01) and AT (P< 0·001) were higher with increasing age. Following 12-month supplementation with EPA plus DHA, adjusted mean difference for change in EPA concentrations in plasma TAG was significantly higher in females than in males (P< 0·05) and was greater with increasing age (P= 0·02). Adjusted mean difference for change in DHA concentrations in AT was significantly smaller with increasing age (P= 0·02). Although small differences in incorporation with age and sex were identified, these were not of sufficient magnitude to warrant a move away from population-level diet recommendations for n-3 PUFA.

We present Herschel-SPIRE imaging spectroscopy (194-671 μm) of the bright starburst galaxy M82. We use RADEX and a Bayesian Likelihood Analysis to simultaneously model the temperature, density, column density, and filling factor of both the cool and warm components of molecular gas traced by the entire CO ladder up to J=13-12. The high-J lines observed by SPIRE trace much warmer gas (~500 K) than those observable from the ground. The addition of 13CO (and [C I]) is new and indicates that [C I] may be tracing different gas than 12CO. At such a high temperature, cooling is dominated by molecular hydrogen; we conclude with a discussion on the possible excitation processes in this warm component. Photon-dominated region (PDR) models require significantly higher densities than those indicated by our Bayesian likelihood analysis in order to explain the high-J CO line ratios, though cosmic-ray enhanced PDR models can do a better job reproducing the emission at lower densities. Shocks and turbulent heating are likely required to explain the bright high-J emission.