On generators of transition semigroups associated to semilinear stochastic partial differential equations

Let $\mathcal{X}$ be a real separable Hilbert space. Let $Q$ be a linear, self-adjoint, positive, trace class operator on $\mathcal{X}$, let $F:\mathcal{X}\rightarrow\mathcal{X}$ be a (smooth enough) function and let $\{W(t)\}_{t\geq 0}$ be a $\mathcal{X}$-valued cylindrical Wiener process. For $\alpha\in [0,1/2]$ we consider the operator $A:=-(1/2)Q^{2\alpha-1}:Q^{1-2\alpha}(\mathcal{X})\subseteq\mathcal{X}\rightarrow\mathcal{X}$. We are interested in the mild solution $X(t,x)$ of the semilinear stochastic partial differential equation \begin{gather} \left\{\begin{array}{ll} dX(t,x)=\big(AX(t,x)+F(X(t,x))\big)dt+ Q^{\alpha}dW(t), & t>0;\\ X(0,x)=x\in \mathcal{X}, \end{array} \right. \end{gather} and in its associated transition semigroup \begin{align} P(t)\varphi(x):=E[\varphi(X(t,x))], \qquad \varphi\in B_b(\mathcal{X}),\ t\geq 0,\ x\in \mathcal{X}; \end{align} where $B_b(\mathcal{X})$ is the space of the real-valued, bounded and Borel measurable functions on $\mathcal{X}$. In this paper we study the behavior of the semigroup $P(t)$ in the space $L^2(\mathcal{X},\nu)$, where $\nu$ is the unique invariant probability measure of \eqref{Tropical}, when $F$ is dissipative and has polynomial growth. Then we prove the logarithmic Sobolev and the Poincar\'e inequalities and we study the maximal Sobolev regularity for the stationary equation $$\lambda u-N_2 u=f,\qquad \lambda>0,\ f\in L^2(\mathcal{X},\nu);$$ where $N_2$ is the infinitesimal generator of $P(t)$ in $L^2(\mathcal{X},\nu)$

A possibly inflated planet around the bright, young star DS Tuc A

The origin of the observed diversity of planetary system architectures is one of the main topic of the exoplanetary research. The detection of a statistically significant sample of planets around young stars allows us to study the early stages of planet formation and evolution, but only a handful of them is known so far. In this regard, a considerable contribution is expected from the NASA TESS satellite, which is now performing a survey of $\sim 85 \%$ of the sky to search for short-period transiting planets In its first month of operations, TESS found a planet candidate with an orbital period of 8.14 days around a member of the Tuc-Hor young association ($\sim$ 40 Myr), the G6V main component of the binary system DS\,Tuc. If confirmed, it would be the first transiting planet around a young star suitable for radial velocity and/or atmospheric characterization. We aim to validate the planetary nature of this companion and to measure its orbital and physical parameters. We obtain accurate planet parameters by coupling an independent reprocessing of the TESS light curve with improved stellar parameters and the dilution caused by the binary companion; we analyse high precision archival radial velocities to impose an upper limit of about 0.1 M$_{\rm Jup}$ on the planet mass; we finally rule out the presence of external companions beyond 40 au with adaptive optics images. We confirm the presence of a young, giant (${\rm R} = 0.50$ R$_{\rm Jup}$) planet having a not negligible possibility to be inflated (theoretical mass $\lesssim 20$ M$_{\oplus}$) around DS\,Tuc~A. We discuss the feasibility of mass determination, Rossiter-McLaughlin analysis and atmosphere characterization, allowed by the brightness of the star.Comment: 12 pages, 11 figures. Accepted for publication in A&

Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation?

The X(3872) is universally accepted to be an exotic hadron. In this letter we assume that the X(3872) is a D0 \bar D0* molecule, as claimed by many authors, and attempt an estimate of its prompt production cross section at Tevatron. A comparison with CDF data allows to draw some qualitative conclusions about this statement.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let

Effects of the combination between selected phytochemicals and the carriers silica and Tween 80 on dry matter and neutral detergent fibre digestibility of common feeds

The overall objective of the current study was to evaluate the effects of 2 carriers (Silica, SIL, and Tween 80, T80) and their interaction with 8 phytochemicals (PCs), on in vitro dry matter and neutral detergent fibre digestibility (DMD, NDFD) of 3 substrates commonly used as feed for dairy cattle (soybean meal, maize meal and total mixed ration –TMR). A total of eight PCs were tested: 4 essential oils (EO) - cinnamon oil (CIN), clove oil (CLO), thyme oil (THY) and oregano oil (ORE) - and 4 essential oil active compounds (EOAC) - cinnamaldehyde (CIN-AC), eugenol (EUG), thymol (THY-AC) and carvacrol (CAR). A positive control with carrier and no PCs was tested for each substrate (CRR). Each PC was tested at 0.5 mg L−1 of medium on DMD and NDFD in an in vitro batch fermentation system. The incubation was performed twice at the intervals of 4 (DMD4, NDFD4) and 24 (DMD24, NDFD24) h. The PCs effect was significant on maize meal and soybean meal DMD24. The carrier’s effect was significant on soybean meal DMD24, indicating a depressive effect of T80 on soybean meal. The PC-carrier interactions were significant on both DMD and NDFD of the tested substrates, except for maize meal and soybean meal DMD24. The PCs-SIL combinations generally increased digestibility while the combination with T80 exerted positive effect only on maize DMD4. The PC-carrier combinations variably affect digestibility of different substrates and these interactions should be considered both for their scientific and commercial implications.HIGHLIGHTS PC-Carrier interactions affect in vitro digestibility. In general, the PC-SIL combinations increase digestibility while those with Tween 80 exert depressing effect. The PC-Carrier effect is variable depending on the degraded substrate

Staphylococcus haemolyticus superinfection of Legionella pneumonia during infliximab therapy

We present the case of a 42-year-old man affected by psoriasis with Staphylococcus Haemolyticus superinfection of Legionella pneumonia during infliximab therapy. The introduction of compounds that block TNF-\u3b1 has yielded great benefits for patients affected by selected autoimmune diseases that fail to respond to classic anti-inflammatory agents, but, on the other hand, has led to an increased susceptibility to infections, in particular of those caused by intracellular pathogens, such as L. Pneumophila. Emerging evidence suggests that legionellosis can be complicated by superinfection with other agents, including saprophytic microorganisms, among which coagulasenegative staphylococci. To our knowledge, this is the first report of systemic legionellosis with superinfection by S. haemolyticus, an emerging nosocomial multi-resistant pathogen that commonly causes septicemia, osteomyelitis or endocarditis, but has not so far been associated with necrotizing pneumonia. Despite the optimal antimicrobial therapy for Staphylococcus spp. Pneumonia is still controversial, evidence suggests that in patients with confirmed positivity for methicillin resistant strains, particularly if sensitivity to vancomycin is suboptimal, linezolid should be the first choice therapy, being superior to vancomycin and teicoplanin

X-ray and ultraviolet emission of the young planet-hosting star V1298 Tau from coordinated observations with XMM-Newton and Hubble Space Telescope

Atmospheric mass loss plays a major role in the evolution of exoplanets. This process is driven by the stellar high-energy irradiation, especially in the first hundreds of millions of years after dissipation of the proto-planetary disk. A major source of uncertainty in modeling atmospheric photoevaporation and photochemistry is due to the lack of direct measurements of the stellar flux at extreme-UV (EUV) wavelengths. Several empirical relationships have been proposed in the past to link EUV fluxes to emission levels in X-rays, but the stellar samples employed for this aim are heterogeneous, and the available scaling laws provide significantly different predictions, especially for very active stars. We present new far-UV and X-ray observations of V1298 Tau with Hubble Space Telescope/Cosmic Origins Spectrograph and XMM-Newton, aimed to determine more accurately the high-energy emission of this solar-mass pre-main-sequence star, which hosts four exoplanets. Spectroscopic data were employed to derive the plasma emission measure distribution versus temperature, from the chromosphere to the corona, and the possible variability of this irradiation on short and year-long timescales, due to magnetic activity. As a side result, we have also measured the chemical abundances of several elements in the outer atmosphere of V1298 Tau. We employ our results as a new benchmark point for the calibration of the X-ray to EUV scaling laws, and hence to predict the time evolution of the irradiation in the EUV band, and its effect on the evaporation of exo-atmospheres

Neutral Iron Emission Lines From The Day-side Of KELT-9b -- The GAPS Programme With HARPS-N At TNG XX

We present the first detection of atomic emission lines from the atmosphere of an exoplanet. We detect neutral iron lines from the day-side of KELT-9b (Teq $\sim$ 4, 000 K). We combined thousands of spectrally resolved lines observed during one night with the HARPS-N spectrograph (R $\sim$ 115, 000), mounted at the Telescopio Nazionale Galileo. We introduce a novel statistical approach to extract the planetary parameters from the binary mask cross-correlation analysis. We also adapt the concept of contribution function to the context of high spectral resolution observations, to identify the location in the planetary atmosphere where the detected emission originates. The average planetary line profile intersected by a stellar G2 binary mask was found in emission with a contrast of 84 $\pm$ 14 ppm relative to the planetary plus stellar continuum (40 $\pm$ 5$\%$ relative to the planetary continuum only). This result unambiguously indicates the presence of an atmospheric thermal inversion. Finally, assuming a modelled temperature profile previously published (Lothringer et al. 2018), we show that an iron abundance consistent with a few times the stellar value explains the data well. In this scenario, the iron emission originates at the $10^{-3}$-$10^{-5}$ bar level.Comment: Accepted for publication on ApJL; 19 pages, 4 figures, 3 table