Optical coherence tomography- a non-invasive technique applied to conservation of paintings

It is current practice to take tiny samples from a painting to mount and examine in cross-section under a microscope. However, since conservation practice and ethics limit sampling to a minimum and to areas along cracks and edges of paintings, which are often unrepresentative of the whole painting, results from such analyses cannot be taken as representative of a painting as a whole. Recently in a preliminary study, we have demonstrated that near-infrared Optical Coherence Tomography (OCT) can be used directly on paintings to examine the cross-section of paint and varnish layers without contact and the need to take samples. OCT is an optical interferometric technique developed for in vivo imaging of the eye and biological tissues; it is essentially a scanning Michelson’s interferometer with a ‘broadband’ source that has the spatial coherence of a laser. The low temporal coherence and high spatial concentration of the source are the keys to high depth resolution and high sensitivity 3D imaging. The technique is non-invasive and noncontact with a typical working distance of 2 cm. This non-invasive technique enables cross-sections to be examined anywhere on a painting. In this paper, we will report new results on applying near-infrared en-face OCT to paintings conservation and extend the application to the examination of underdrawings, drying processes, and quantitative measurements of optical properties of paint and varnish layers

New driver alterations in non-small cell lung cancer. A narrative review

Objective: This review aims to provide an up-to-date snapshot on the state of development of novel biomarker-driven treatments in non-small cell lung cancer (NSCLC). Background: The introduction of immune checkpoint inhibitors and target therapies has revolutionized the natural history of many NSCLCs, allowing for lasting and profound responses. In particular, mutations in the epidermal growth factor receptor (EGFR), rearrangements of the anaplastic lymphoma kinase (ALK), or oncogene c-Ros 1 (ROS1) have marked a paradigm shift in the treatment of NSCLC. Furthermore, new inhibitors for B-Raf proto-oncogene (BRAF), rearranged during transfection (RET), mesenchymal-to-epithelial transition factor (MET), or neurotrophic tyrosine kinase (NTRK) 1–3 have revealed fascinating data, obtaining accelerated approvals from the Food and Drug Administration (FDA) and European Medicines Agency (EMA). Today, the extensive use of next-generation sequencing (NGS) techniques has shown a broad molecular heterogeneity of NSCLC. Many of the mutations identified are considered potential therapeutic targets, and numerous studies are currently evaluating the efficacy of selective inhibitors. Methods: We carried out an extensive review of the literature on PubMed, Web of Science, and Scopus databases and the congress abstracts presented at the American Society of Clinical Oncology (ASCO), European Society for Medical Oncology (ESMO), and World Conference on Lung Cancer (WCLC) in the last 5 years. Our analysis considered works regarding new inhibitors for alterations of Kirsten rat sarcoma viral oncogene homolog (KRAS), PIK3CA, neuregulin-1 (NRG-1), human epidermal growth factor receptor 2 (HER2), fibroblast growth factor receptor (FGFR), genes that have recently become no longer undruggable. Conclusions: Precision oncology is revolutionizing the natural history of NSCLC. Several alterations have been identified as possible treatment targets, and numerous inhibitors show promising results in ongoing clinical trials

Bimodal Color Distribution in Hierarchical Galaxy Formation

We show how the observed bimodality in the color distribution of galaxies can be explained in the framework of the hierarchical clustering picture in terms of the interplay between the properties of the merging histories and the feedback/star-formation processes in the progenitors of local galaxies. Using a semi-analytic model of hierarchical galaxy formation, we compute the color distributions of galaxies with different luminosities and compare them with the observations. Our fiducial model matches the fundamental properties of the observed distributions, namely: 1) the distribution of objects brighter than M_r = -18 is clearly bimodal, with a fraction of red objects increasing with luminosity; 2) for objects brighter than M_r = -21 the color distribution is dominated by red objects with color u-r = 2.2-2.4; 3) the spread on the distribution of the red population is smaller than that of the blue population; 4) the fraction of red galaxies is larger in denser environments, even for low-luminosity objects; 5) the bimodality in the distribution persists up to z = 1.5. We discuss the role of the different physical processes included in the model in producing the above results.Comment: 11 pages, accepted for publication in the Astrophysical Journa

The evolving slope of the stellar mass function at 0.6 <= z < 4.5 from deep WFC3 data

We used Early Release Science (ERS) observations taken with the Wide Field Camera 3 (WFC3) in the GOODS-S field to study the galaxy stellar mass function (GSMF) at 0.6<=z<4.5. Deep WFC3 near-IR data (for Y as faint as 27.3, J and H as faint as 27.4 AB mag at 5 sigma), as well as deep Ks (as faint as 25.5 at 5 sigma) Hawk-I band data, provide an exquisite data set with which determine in an unprecedented way the low-mass end of the GSMF, allowing an accurate probe of masses as low as M~7.6 10^9 Msun at z~3. Although the area used is relatively small (~33 arcmin^2), we found generally good agreement with previous studies on the entire mass range. Our results show that the slope of the faint-end increases with redshift, from alpha=-1.44+/-0.03 at z~0.8 to alpha=-1.86+/-0.16 at z~3, although indications exist that it does not steepen further between z~3 and z~4. This result is insensitive to any uncertainty in the M* parameter. The steepness of the GSMF faint-end solves the well-known disagreement between the stellar mass density (SMD) and the integrated star formation history at z>2. However, we confirm the that there appears to be an excess of integrated star formation with respect to the SMD at z<2, by a factor of ~2-3. Our comparison of the observations with theoretical predictions shows that the models forecast a greater abundance of low mass galaxies, at least up to z~3, as well as a dearth of massive galaxies at z~4 with respect to the data, and that the predicted SMD is generally overestimated at z<~2.Comment: Accepted for publication in Astronomy & Astrophysics. Minor language editin

Evidence for a fast evolution of the UV luminosity function beyond redshift 6 from a deep HAWK-I survey of the GOODS-S field

We perform a deep search for galaxies in the redshift range 6.5<z<7.5, to measure the evolution of the number density of luminous galaxies in this redshift range and derive useful constraints on the evolution of their Luminosity Function. We present here the first results of an ESO Large Program, that exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained two Hawk-I pointings on the GOODS South field for a total of 32 observing hours, covering ~90 arcmin2. The images reach Y=26.7 mags for the two fields. We have used public ACS images in the z band to select z-dropout galaxies with the colour criteria Z-Y>1, Y-J<1.5 and Y-K<2. The other public data in the UBVRIJHK bands are used to reject possible low redshift interlopers. The output has been compared with extensive Monte Carlo simulations to quantify the observational effects of our selection criteria as well as the effects of photometric errors. We detect 7 high quality candidates in the magnitude range Y=25.5-26.7. This interval samples the critical range for M* at z>6 (M_1500 ~- 19.5 to -21.5). After accounting for the expected incompleteness, we rule out at a 99% confidence level a Luminosity Function constant from z=6 to z=7, even including the effects of cosmic variance. For galaxies brighter than M_1500=-19.0 we derive a luminosity density rho_UV=1.5^{+2.0}_{-0.9} 10^25 erg/s/Hz/Mpc3, implying a decrease by a factor 3.5 from z=6 to z~6.8. On the basis of our findings, we make predictions for the surface densities expected in future surveys surveys, based on ULTRA-VISTA, HST-WFC3 or JWST-NIRCam, evaluating the best observational strategy to maximise their impact.Comment: Accepted for publication in Astronomy & Astrophysic

The Morphology of Passively Evolving Galaxies at Z approximately 2 from HST/WFC3 Deep Imaging in the Hubble Ultradeep Field

We present near-IR images of six passive galaxies (SSFR< 10(exp -2)/ Gyr) at redshift 1.3 < z < 2.4 with stellar mass M approximately 10(exp 11) solar M, selected from the Great Observatories Origins Deep Survey (GOODS), obtained with the Hubble Space Telescope (HST) and the WFC3/IR camera. These images provide the deepest and highest angular resolution view of the optical rest-frame morphology of such systems to date. We find that the light profile of these galaxies is generally regular and well described by a Sersic model with index typical of today's spheroids. We confirm the existence of compact and massive early-type galaxies at z approximately 2: four out of six galaxies have r(sub e) approximately 1 kpc or less. The images reach limiting surface brightness mu approximates 26.5 mag/square arcsec in the F160W bandpass; yet there is no evidence of a faint halo in the galaxies of our sample, even in their stacked image. We also find very weak "morphological k-correction" in the galaxies between the rest-frame UV (from the ACS z-band), and the rest-frame optical (WFC3 H-band): the visual classification, Sersic indices and physical sizes of these galaxies are independent or only mildly dependent on the wavelength, within the errors. The presence of an active nucleus is suspected in two out of six galaxies (33%), opening the intriguing possibility that a large, presently unaccounted population of AGN is hosted in these galaxies, possibly responsible for the cessation of star formation

The K20 survey. VI. The Distribution of the Stellar Masses in Galaxies up to z~2

We present a detailed analysis of the stellar mass content of galaxies up to z=2.5 in the K20 galaxy sample, that has a 92% spectroscopic completeness and a complete $UBVRIzJK_s$ multicolor coverage. We find that the M/L ratio decreases with redshift: in particular, the average M/L ratio of early type galaxies decreases with $z$, with a scatter that is indicative of a range of star--formation time-scales and redshift of formation. More important, the typical M/L of massive early type galaxies is larger than that of less massive ones, suggesting that their stellar population formed at higher z. The final K20 galaxy sample spans a range of stellar masses from M*=10^9Msun to M*=10^12Msun, with massive galaxies ($M*>10^11Msun) detected up to z~2. We compute the Galaxy Stellar Mass Function at various z, of which we observe only a mild evolution (i.e. by 20-30%) up to z~1. At z>1, the evolution of the GSMF appears to be much faster: at z~2, about 35% of the present day stellar mass in objects with M*~10^11Msun appear to have assembled. We also detect a change in the physical nature of the most massive galaxies, since at z>1 a population of massive star--forming galaxies progressively appears. We finally analyze our results in the framework of Lambda-CDM hierarchical models. First, we show that the large number of massive galaxies detected at high z does not violate any fundamental Lambda-CDM constraint based on the number of massive DM halos. Then, we compare our results with the predictions of renditions of both semianalytic and hydro-dynamical models, that range from severe underestimates to slight overestimates of the observed mass density at z<~2. We discuss how the differences among these models are due to the different implementation of the main physical processes. (Abridged)Comment: Accepted for publication on Astronomy & Astrophysic

Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission

Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of galaxies show a strong evolution from $z = 0$ to $z = 1$, but the FIR LF evolves much stronger than the FUV one. The FUV is dominantly radiated from newly formed short-lived OB stars, while the FIR is emitted by dust grains heated by the FUV radiation field. It is known that dust is always associated with star formation activity. Thus, both FUV and FIR are tightly related to the star formation in galaxies, but in a very complicated manner. In order to disentangle the relation between FUV and FIR emissions, we estimate the UV-IR bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey datasets. Recently we invented a new mathematical method to construct the BLF with given marginals and prescribed correlation coefficient. This method makes use of a tool from mathematical statistics, so called "copula". The copula enables us to construct a bivariate distribution function from given marginal distributions with prescribed correlation and/or dependence structure. With this new formulation and FUV and FIR univariate LFs, we analyze various FUV and FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR BLF. The obtained BLFs naturally explain the nonlinear complicated relation between FUV and FIR emission from star-forming galaxies. Though the faint-end of the BLF was not well constrained for high-$z$ samples, the estimated linear correlation coefficient $\rho$ was found to be very high, and is remarkably stable with redshifts (from 0.95 at $z = 0$ to 0.85 at $z = 1.0$). This implies the evolution of the UV-IR BLF is mainly due to the different evolution of the univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres

The bright end of the z ~ 7 UV Luminosity Function from a wide and deep HAWK-I survey

(Abridged) We present here the second half of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained - 30 observing hours with Hawk-I in the Y-band of two high galactic latitude fields. We combined the Y-band data with deep J and K Hawk-I observations, and with FORS1/FORS2 U, B, V, R, I, and Z observations to select z-drop galaxies having Z - Y > 1, no optical detection and flat Y - J and Y - K colour terms. We detect 8 high-quality candidates in the magnitude range Y = 25.5 - 26.5 that we add to the z-drop candidates selected in two Hawk-I pointings over the GOODS-South field. We use this full sample of 15 objects found in -161 arcmin^2 of our survey to constrain the average physical properties and the evolution of the number density of z ~ 7 LBGs. A stacking analysis yields a best-fit SED with photometric redshift z= 6.85 +0.20 -0.15 and an E(B-V)=0.05 +0.15 -0.05. We compute a binned estimate of the z ~ 7 LF and explore the effects of photometric scatter and model uncertainties on the statistical constraints. After accounting for the expected incompleteness through MonteCarlo simulations, we strengthen our previous finding that a Schechter luminosity function constant from z=6 to z=7 is ruled out at a >99% confidence level, even including the effects of cosmic variance. For galaxies brighter than M_1500= -19.0, we derive a luminosity density rho_UV = 1.5^{+2.1}{-0.8} x 10^25 erg/s/Hz/Mpc^3, implying a decrease by a factor 3.5 from z=6 to z=6.8. We find that, under standard assumptions, the emission rate of ionizing photons coming from UV bright galaxies is lower by at least a factor of two than the value required for reionization. Finally, we exploit deep Hawk-I J and K band observations to derive an upper limit on the number density of M1500<~ -22.0 LBGs at z-8 (Y-dropouts).Comment: 12 pages, 8 figures. Accepted for publication in Astronomy & Astrophysic