Uncertainties in gas kinematics arising from stellar continuum modelling in integral field spectroscopy data: the case of NGC2906 observed with MUSE/VLT

We study how the use of several stellar subtraction methods and line fitting approaches can affect the derivation of the main kinematic parameters (velocity and velocity dispersion fields) of the ionized gas component. The target of this work is the nearby galaxy NGC 2906, observed with the MUSE instrument at Very Large Telescope. A sample of twelve spectra is selected from the inner (nucleus) and outer (spiral arms) regions, characterized by different ionization mechanisms. We compare three different methods to subtract the stellar continuum (FIT3D, STARLIGHT and pPXF), combined with one of the following stellar libraries: MILES, STELIB and GRANADA+MILES. The choice of the stellar subtraction method is the most important ingredient affecting the derivation of the gas kinematics, followed by the choice of the stellar library and by the line fitting approach. In our data, typical uncertainties in the observed wavelength and width of the H\alpha and [NII] lines are of the order of _rms \sim 0.1\AA\ and _rms \sim 0.2\AA\ (\sim 5 and 10km/s, respectively). The results obtained from the [NII] line seem to be slightly more robust, as it is less affected by stellar absorption than H\alpha. All methods considered yield statistically consistent measurements once a mean systemic contribution \Delta\bar\lambda=\Delta\bar\sigma=0.2xDelta_{MUSE} is added in quadrature to the line fitting errors, where \Delta_{MUSE} = 1.1\AA\ \sim 50 km/s denotes the instrumental resolution of the MUSE spectra. Although the subtraction of the stellar continuum is critical in order to recover line fluxes, any method (including none) can be used in order to measure the gas kinematics, as long as an additional component of 0.2 x Delta_MUSE is added to the error budget.Comment: 20 pages, 14 figure

Impact and costs of proposed scenarios for power sector decarbonisation: An Italian case study

In the face of ever more ambitious global energy challenges, the European Union has set striving climate targets for 2030, planning to increase renewable energy penetration in the electricity generation as a key measure towards a clean energy transition. To respond to the challenge of keeping the increase in power sector costs, that inevitably arises when a profound reconfiguration of the electricity generation sector is expected, to the lowest possible, this paper aims to quantify the economic burden associated with the reduction of direct CO2 emissions through a comparative assessment of various alternatives proposed for 2030 ranked in terms of their cost-effectiveness. A sensitivity analysis is also applied to the main economic and energy parameters that make up CO2 mitigation costs to include those uncertainties that characterise future projections. The impact of electricity generation shares on CO2 mitigation costs is assessed thus providing a basis for the definition of alternative configurations for the Italian electricity sector capable to achieve the desired environmental performance with a limited economic impact. Finally, results reveal that those scenarios based largely on natural gas and solar source are characterized by high mitigation costs, while energy efficiency is essential for a virtuous and clean electricity sector along with the use of all available sources in appropriate shares, both renewable and non-renewable, to pursue the highest environmental objectives in a cost-effective manner. Although related to the Italian case, the methodology provided in this study can be applied to any other electricity sector to ultimately evaluate the economic burden arising from possible different configurations

Modelling transpiration of greenhouse gerbera (Gerbera jamesonii H. Bolus) grown in substrate with saline water in a Mediterranean climate

Gerbera plants were grown in semi-closed rockwool culture under greenhouse conditions in different seasons in a Mediterranean climate. The plants were irrigated using either fresh (FW; 1.0 mol m−3NaCl)or moderately saline (SW; 9.0 mol m−3NaCl) water. In autumn, NaCl concentration did not influence significantly plant growth, flower production and transpiration (E), which instead were reduced in springin the plants irrigated with SW. In both seasons, water salinity did not affect leaf stomatal resistance (rl),which was determined by the inversion of the Penman–Monteith (PM) equation or measured with a diffusion porometer. The PM formula and two regression equations were calibrated and validated for estimating the hourly rate of daytime transpiration (Ed); a regression model was also fit to nocturnal transpiration (En). Regression models predicted Edas a function of vapour pressure deficit (VPD) and/or the radiation intercepted by the canopy. Leaf area index (LAI), which is required by all the equations, was modelled as function of crop thermal time (i.e. growing degree days). The PM model predicted Ed using a constant value of rl. Model calibration and validation were performed using independent data sets. The irrigation with FW or SW did not require a different calibration of transpiration models. Both PM formula and regression equations provided accurate estimates of Ed; fitted equations explained between 80% and96% of the variance in measured Ed. A linear regression of En against (LAI·VPD) accounted for 92% of measured En

Cardiopulmonary exercise testing in a combined screening approach to individuate pulmonary arterial hypertension in systemic sclerosis

Objectives The DETECT algorithm has been developed to identify SSc patients at risk for pulmonary arterial hypertension (PAH) yielding high sensitivity but low specificity, and positive predictive value. We tested whether cardiopulmonary exercise testing (CPET) could improve the performance of the DETECT screening strategy. Methods Consecutive SSc patients over a 30-month period were screened with the DETECT algorithm and positive subjects were referred for CPET before the execution of right-heart catheterization. The predictive performance of CPET on top of DETECT was evaluated and internally validated via bootstrap replicates. Results Out of 314 patients, 96 satisfied the DETECT application criteria and 54 were positive. PAH was ascertained in 17 (31.5%) and pre-capillary pulmonary hypertension in 23 (42.6%) patients. Within CPET variables, the slope of the minute ventilation to carbon dioxide production relationship (VE/VCO2 slope) had the best performance to predict PAH at right-heart catheterization [median (interquartile range) of specificity 0.778 (0.714\u20130.846), positive predictive value 0.636 (0.556\u20130.750)]; exploratory analysis on pre-capillary yielded a specificity of 0.714 (0.636\u20130.8) and positive predictive value of 0.714 (0.636\u20130.8). Conclusion In association with the DETECT algorithm, CPET may be considered as a useful tool in the workup of SSc-related pulmonary hypertension. The sequential determination of the VE/VCO2 slope in DETECT-positive subjects may reduce the number of unnecessary invasive procedures without any loss in the capability to capture PAH. This strategy had also a remarkable performance in highlighting the presence of pre-capillary pulmonary hypertension

Projecting grassland sensitivity to climate change from an ensemble of models

The grassland biome covers about one-quarter of the earth’s land area and contributes to the livelihoods of ca. 800 million people. Increased aridity and persistent droughts are projected in the twenty-first century for most of Africa, southern Europe and the Middle East, most of the Americas, Australia and South East Asia. A number of these regions have a large fraction of their land use covered by grasslands and rangelands. Grasslands are the ecosystems that respond most rapidly to precipitation variability. However, global projections of climate change impacts on grasslands are still lacking in the scientific literature. Within AgMIP, based on the C3MP protocol initially developed for crops, we have explored the sensitivity of temperate grasslands to climate change drivers with an ensemble of models. Site calibrated models are used to provide projections under probabilistic climate change scenarios, which are defined by a combination of air temperature, precipitation and atmospheric CO2 changes resulting in 99 runs for each model times site combination. This design provides a test of grassland production, GHG (N2O and CH4) emissions and soil carbon sensitivity to climate change drivers. This integrated approach has been tested for 12 grassland simulation models applied to 19 sites over three continents. We show here that a single polynomial emulator can be fitted with high significance to the results of all models and sites, when these are expressed as relative changes from the optimal combination of climate drivers. This polynomial emulator shows that elevated atmospheric CO2 expands the thermal and hydric range which allows for the development of temperate grasslands. Moreover, we calculate the climatic response surface of GHG emissions per unit grassland production and we show that this surface varies with elevated CO2. From these results we provide first estimates of the impacts of climate change on temperate grasslands based on a range of climate scenarios

Limited impact of jet induced feedback in the multi-phase nuclear interstellar medium of 4C12.50

Although the ultraluminous infrared radio galaxy 4C12.50 at z=0.12 is a promising candidate to reveal how radio induced feedback may regulate star formation in galaxies, we find no solid evidence for current or past impact of this mechanism on the evolution of this system, neither by clearing out the dusty central cocoon efficiently, nor by suppressing star formation. We study in detail for the first time the hot (>~1500 K) molecular gas in this object. The potential impact of the radio jet on this gas phase, as well as on the star formation activity, are investigated. 4C12.50 hosts (2.1+/-0.4)x1e4 Msun of hot molecular gas. An unusually high rotational temperature T =3020+/-160 K is inferred. The molecular gas mass obeys a power law temperature distribution d(M(H2))/dT ~ T^-5 from T~300 K and up to ~3000 K. Both results support that shocks (probably induced by the radio jet) contribute to the heating and excitation of the hot molecular gas. A molecular outflow is not detected. The coupling of the outflowing ionized and neutral outflows with the hot molecular gas is poor. We find no evidence for star formation supression. NIR and MIR integral field spectroscopy at very high spatial resolution (for instance, with the JWST) would be of key value to further investigate these issues.Comment: Accepted for publication in A&A,18 pages, 13 figure

Modulation of Human Immunodeficiency Virus 1 Replication by Interferon Regulatory Factors

Transcription of the human immunodeficiency virus (HIV)-1 is controlled by the cooperation of virally encoded and host regulatory proteins. The Tat protein is essential for viral replication, however, expression of Tat after virus entry requires HIV-1 promoter activation. A sequence in the 5′ HIV-1 LTR, containing a binding site for transcription factors of the interferon regulatory factors (IRF) family has been suggested to be critical for HIV-1 transcription and replication. Here we show that IRF-1 activates HIV-1 LTR transcription in a dose-dependent fashion and in the absence of Tat. This has biological significance since IRF-1 is produced early upon virus entry, both in cell lines and in primary CD4+ T cells, and before expression of Tat. IRF-1 also cooperates with Tat in amplifying virus gene transcription and replication. This cooperation depends upon a physical interaction that is blocked by overexpression of IRF-8, the natural repressor of IRF-1, and, in turn is released by overexpression of IRF-1. These data suggest a key role of IRF-1 in the early phase of viral replication and/or during viral reactivation from latency, when viral transactivators are absent or present at very low levels, and suggest that the interplay between IRF-1 and IRF-8 may play a key role in virus latency

Physics of ULIRGs with MUSE and ALMA: The PUMA project: I. Properties of the survey and first MUSE data results

Ultraluminous infrared galaxies (ULIRGs) are characterised by extreme starburst (SB) and AGN activity, and are therefore ideal laboratories for studying the outflow phenomena. We have recently started a project called Physics of ULIRGs with MUSE and ALMA (PUMA), which is a survey of 25 nearby (z < 0.165) ULIRGs observed with the integral field spectrograph MUSE and the interferometer ALMA. This sample includes systems with both AGN and SB nuclear activity in the pre- and post-coalescence phases of major mergers. The main goals of the project are to study the prevalence of multi-phase outflows as a function of the galaxy properties, to constrain the driving mechanisms of the outflows (e.g. distinguish between SB and AGN winds), and to identify feedback effects on the host galaxy. In this first paper, we present details on the sample selection, MUSE observations, and derive first data products. MUSE data were analysed to study the dynamical status of each of the 21 ULIRGs observed so far, taking the stellar kinematics and the morphological properties inferred from MUSE narrow-band images into account. We also located the ULIRG nuclei, using near-IR (HST) and mm (ALMA) data, and studied their optical spectra to infer the ionisation state through BPT diagnostics, and outflows in both ionised and neutral gas. We show that the morphological and stellar kinematic classifications are consistent: post-coalescence systems are more likely associated with ordered motions, while interacting (binary) systems are dominated by non-ordered and streaming motions. We also find broad and asymmetric [OIII] and NaID profiles in almost all nuclear spectra, with line widths in the range 300-2000 km/s, possibly associated with AGN- and SB-driven winds. This result reinforces previous findings that indicated that outflows are ubiquitous during the pre- and post-coalescence phases of major mergers.ERC STF