Understanding the formation and evolution of giant planets (≥1 MJup) at wide orbital separation (≥5 AU) is one of the goals of direct imaging. Over the past 15 yr, many surveys have placed strong ...constraints on the occurrence rate of wide-orbit giants, mostly based on non-detections, but very few have tried to make a direct link with planet formation theories. In the present work, we combine the results of our previously published VLT/NaCo large program with the results of 12 past imaging surveys to constitute a statistical sample of 199 FGK stars within 100 pc, including three stars with sub-stellar companions. Using Monte Carlo simulations and assuming linear flat distributions for the mass and semi-major axis of planets, we estimate the sub-stellar companion frequency to be within 0.75–5.70% at the 68% confidence level (CL) within 20–300 AU and 0.5–75 MJup, which is compatible with previously published results. We also compare our results with the predictions of state-of-the-art population synthesis models based on the gravitational instability (GI) formation scenario with and without scattering. We estimate that in both the scattered and non-scattered populations, we would be able to detect more than 30% of companions in the 1–75 MJup range (95% CL). With the threesub-stellar detections in our sample, we estimate the fraction of stars that host a planetary system formed by GI to be within 1.0–8.6% (95% CL). We also conclude that even though GI is not common, it predicts a mass distribution of wide-orbit massive companions that is much closer to what is observed than what the core accretion scenario predicts. Finally, we associate the present paper with the release of the Direct Imaging Virtual Archive (DIVA), a public database that aims at gathering the results of past, present, and future direct imaging surveys.
We report the first observed Pd-catalyzed isomerization (“cage-walking”) of B(9)-bromo-meta-carborane during Pd-catalyzed cross-coupling, which enables the formation of B–O and B–N bonds at all boron ...vertices (B(2), B(4), B(5), and B(9)) of meta-carborane. Experimental and theoretical studies suggest this isomerization mechanism is strongly influenced by the steric crowding at the Pd catalyst by either a biaryl phosphine ligand and/or substrate. Ultimately, this “cage-walking” process provides a unique pathway to preferentially introduce functional groups at the B(2) vertex using B(9)-bromo-meta-carborane as the sole starting material through substrate control.
Bone quality in Duchenne muscular dystrophy Catalano, A.; Vita, G. L.; Messina, S.
Journal of endocrinological investigation,
06/2022, Letnik:
45, Številka:
6
Journal Article
Context.
Young nearby stars are good candidates in the search for planets with both radial velocity (RV) and direct imaging techniques. This, in turn, allows for the computation of the giant planet ...occurrence rates at all separations. The RV search around young stars is a challenge as they are generally faster rotators than older stars of similar spectral types and they exhibit signatures of magnetic activity (spots) or pulsation in their RV time series. Specific analyses are necessary to characterize, and possibly correct for, this activity.
Aims.
Our aim is to search for planets around young nearby stars and to estimate the giant planet (GP) occurrence rates for periods up to 1000 days.
Methods.
We used the HARPS spectrograph on the 3.6 m telescope at La Silla Observatory to observe 89
A
−
M
young (<600 Myr) stars. We used our SAFIR (Spectroscopic data via Analysis of the Fourier Interspectrum Radial velocities) software to compute the RV and other spectroscopic observables. Then, we computed the companion occurrence rates on this sample.
Results.
We confirm the binary nature of HD 177171, HD 181321 and HD 186704. We report the detection of a close low mass stellar companion for HIP 36985. No planetary companion was detected. We obtain upper limits on the GP (<13
M
Jup
) and BD (∈ 13;80
M
Jup
) occurrence rates based on 83 young stars for periods less than 1000 days, which are set, 2
−2
+3
and 1
−1
+3
%.
•Double seropositivity can occur in MG old patients with a benign course.•Clinicians should detect both AChR and MuSK Abs under certain conditions.•We discuss all the other cases of double positive ...MG reported in literature.
AChR and MuSK double positive myasthenia gravis has been rarely reported. Generally, it occurs in children and adults after thymectomy or immunotherapy. Furthermore, in a few patients with bulbar or respiratory involvement, MuSK antibodies might be detected after clinical deterioration. We report a man with a very late onset myasthenia gravis (86-year-old) and the coexistence of both antibodies at the time of the diagnosis. Despite the presence of MuSK antibodies, he manifested no bulbar symptoms and had a favorable clinical outcome. However, side effects related to low dose pyridostigmine were evident. Hence, double positivity can also occur in elderly and in more benign forms of myasthenia gravis. Other cases of AChR and MuSK double positive myasthenia gravis could allow a better definition of this condition.
Polymorphous low-grade neuroepithelial tumors of the young (PLNTYs) are recently described CNS tumors. Classically, PLNTYs are epileptogenic and are a subtype of a heterogeneous group of low-grade ...neuroepithelial tumors that cause refractory epilepsy, such as angiocentric gliomas, oligodendrogliomas, gangliogliomas, and pleomorphic xanthoastrocytomas. Although they are a relatively new entity, a number of imaging and histologic characteristics of PLNTYs are already known. We present the imaging and pathologic findings of such a tumor as well as the surgical approach and clinical management.
•A branched pipe network in a solar collector with a disc-shaped body for a nanofluid flow is developed.•The size of the pipe network for a nanofluid flow are smaller than a base fluid flow.•Optimal ...size of ramifications and thermal resistance of every level of construction are obtained for a nanofluid flow.
We have developed a network of pipes of dendritic geometry in a solar collector with a disc-shaped body. The fluid in the network pipes is a nanofluid composed of a mixture of nanoparticles of alumina (Al2O3) and water as a base fluid in order to harvest a greater amount of thermal energy from incoming solar radiation. The sizes of the network pipes are obtained by using constructal theory methods. Thermal conductivity was obtained by the Hamilton-Crosser model; physical properties such as density and specific heat capacity were described as a function of the volumetric fraction of nanoparticles in the fluid. Optimal size of the network presented for every level of construction was established by the condition of minimal thermal resistance. Temperature profiles and the aspect ratio of the construction elements were defined as a function of the volumetric fraction of nanoparticles. Results show that by increasing the volume fraction of nanoparticles, thermal energy gain also increases, reaching a higher outlet temperature of the fluid when alumina nanoparticles are used.
Context. Magnetic cycles analogous to the solar cycle have been detected in tens of solar-like stars by analyzing long-term time series of different magnetic activity indexes. The relationship ...between the cycle properties and global stellar parameters is not fully understood yet. One reason for this is the lack of long-term time series for stars covering a wide range of stellar parameters. Aims. We searched for activity cycles in a sample of 90 young solar-like stars with ages between 4 and 95 Myr with the aim to investigate the properties of activity cycles in this age range. Methods. We measured the length Pcyc of a given cycle by analyzing the long-term time series of three different activity indexes: the period of rotational modulation, the amplitude of the rotational modulation and the median magnitude in the V band. For each star, we also computed the global magnetic activity index ⟨ IQR ⟩ that is proportional to the amplitude of the rotational modulation and can be regarded as a proxy of the mean level of the surface magnetic activity. Results. We detected activity cycles in 67 stars. Secondary cycles were also detected in 32 stars of the sample. The lack of correlation between Pcyc and Prot and the position of our targets in the Pcyc/Prot−Ro-1 diagram suggest that these stars belong to the so-called transitional branch and that the dynamo acting in these stars is different from the solar dynamo and from that acting in the older Mt. Wilson stars. This statement is also supported by the analysis of the butterfly diagrams whose patterns are very different from those seen in the solar case. We computed the Spearman correlation coefficient rS between Pcyc, ⟨ IQR ⟩ and various stellar parameters. We found that Pcyc in our sample is uncorrelated with all the investigated parameters. The ⟨ IQR ⟩ index is positively correlated with the convective turnover timescale, the magnetic diffusivity timescale τdiff, and the dynamo number DN, whereas it is anti-correlated with the effective temperature Teff, the photometric shear ΔΩphot and the radius RC at which the convective zone is located. We investigated how Pcyc and ⟨ IQR ⟩ evolve with the stellar age. We found that Pcyc is about constant and that ⟨ IQR ⟩ decreases with the stellare age in the range 4–95 Myr. Finally we investigated the magnetic activity of the star AB Dor A by merging All Sky Automatic Survey (ASAS) time series with previous long-term photometric data. We estimated the length of the AB Dor A primary cycle as Pcyc = 16.78 ± 2 yr and we also found shorter secondary cycles with lengths of 400 d, 190 d, and 90 d, respectively.
Abstract The motor skills of patients with spinal muscular atrophy, type I (SMA-I) are very limited. It is difficult to quantify the motor abilities of these patients and as a result there is ...currently no validated measure of motor function that can be utilized as an outcome measure in clinical trials of SMA-I. We have developed the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (“CHOP INTEND”) to evaluate the motor skills of patients with SMA-I. The test was developed following the evaluation of 26 infants with SMA-I mean age 11.5 months (1.4–37.9 months) with the Test of Infant Motor Performance and The Children’s Hospital of Philadelphia Test of Strength in SMA, a newly devised motor assessment for SMA. Items for the CHOP INTEND were selected by an expert panel based on item mean and standard deviation, item frequency distribution, and Chronbach’s alpha. Intra-rater reliability of the resulting test was established by test–retest of 9 infants with SMA-I over a 2 month period; Intraclass correlation coefficient (ICC) (3,1) = 0.96. Interrater reliability was by video analysis of a mixed group of infants with neuromuscular disease by 4 evaluators; ICC (3,4) = 0.98 and in a group of 8 typically developing infants by 5 evaluators ICC (3,5) = 0.93. The face validity of the CHOP INTEND is supported by the use of an expert panel in item selection; however, further validation is needed. The CHOP INTEND is a reliable measure of motor skills in patients with SMA-I and neuromuscular disorders presenting in infancy.
Young, close stars are ideal targets for searching planets using the direct imaging technique. We have conducted a large program with NaCo at the VLT to search for planets and brown dwarfs in wide ...orbits around 86 stars. A large fraction of the targets observed with NaCo were poorly investigated in the literature. We performed a study to characterize the fundamental properties of the stars in our sample. To improve target age determinations, we compiled and analyzed a complete set of age diagnostics. We measured spectroscopic parameters and age diagnostics using dedicated observations acquired with FEROS and CORALIE spectrographs at La Silla Observatory. We provided updated characterization of all the targets observed in the VLT NaCo Large program, a survey designed to probe the occurrence of exoplanets and brown dwarfs in wide orbits. Several stars are confirmed or proposed here to be members of close young moving groups. Eight spectroscopic binaries are identified.
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