scholarly journals Testing exoplanet evaporation with multitransiting systems

2019 ◽  
Vol 491 (4) ◽  
pp. 5287-5297 ◽  
Author(s):  
James E Owen ◽  
Beatriz Campos Estrada
Keyword(s):  
Radial Velocity ◽  
Excellent Agreement ◽  
Minimum Mass ◽  
Mass Measurements ◽  
Evolutionary Pathway ◽  
X Ray ◽  
Transiting Planets ◽  
Formation History

ABSTRACT The photoevaporation model is one of the leading explanations for the evolution of small, close-in planets and the origin of the radius-valley. However, without planet mass measurements, it is challenging to test the photoevaporation scenario. Even if masses are available for individual planets, the host star’s unknown EUV/X-ray history makes it difficult to assess the role of photoevaporation. We show that systems with multiple transiting planets are the best in which to rigorously test the photoevaporation model. By scaling one planet to another in a multitransiting system, the host star’s uncertain EUV/X-ray history can be negated. By focusing on systems that contain planets that straddle the radius-valley, one can estimate the minimum masses of planets above the radius-valley (and thus are assumed to have retained a voluminous hydrogen/helium envelope). This minimum mass is estimated by assuming that the planet below the radius-valley entirely lost its initial hydrogen/helium envelope, then calculating how massive any planet above the valley needs to be to retain its envelope. We apply this method to 104 planets above the radius gap in 73 systems for which precise enough radii measurements are available. We find excellent agreement with the photoevaporation model. Only two planets (Kepler-100c and 142c) appear to be inconsistent, suggesting they had a different formation history or followed a different evolutionary pathway to the bulk of the population. Our method can be used to identify TESS systems that warrant radial-velocity follow-up to further test the photoevaporation model. The software to estimate minimum planet masses is publicly available at https://github.com/jo276/EvapMass.

scholarly journals Chest CT as a Complement to RT-PCR to Confirm and Follow-up COVID-19 Patients

Medicinus ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 31
Author(s):  
Aziza Ghanie Icksan ◽  
Muhammad Hafiz ◽  
Annisa Dian Harlivasari
Keyword(s):  
Chest Ct ◽  
Rt Pcr ◽  
High Resolution Computed Tomography ◽  
X Ray ◽  
First Case ◽  
Chest X Ray ◽  
Polymerase Chain

<p><strong>Background : </strong>The first case of COVID-19 in Indonesia was recorded in March 2020. Limitation of reverse-transcription polymerase chain reaction (RT-PCR) has put chest CT as an essential complementary tool in the diagnosis and follow up treatment for COVID-19. Literatures strongly suggested that High-Resolution Computed Tomography (HRCT) is essential in diagnosing typical symptoms of COVID-19 at the early phase of disease due to its superior sensitivity  (97%) compared to chest x-ray (CXR).</p><p>The two cases presented in this case study showed the crucial role of chest CT with HRCT to establish the working diagnosis and follow up COVID-19 patients as a complement to RT-PCR, currently deemed a gold standard.<strong></strong></p>

scholarly journals Consensus Guidelines of Russian Society of Radiology (RSR) and Russian Association of Specialists in Ultrasound Diagnostics in Medicine (RASUDM) «Role of Imaging (X-ray, CT and US) in Diagnosis of COVID-19 Pneumonia» (version 2)

2020 ◽  
Vol 101 (2) ◽  
pp. 72-89
Author(s):  
V. E. Sinitsyn ◽  
I. E. Tyurin ◽  
V. V. Mitkov
Keyword(s):  
Intensive Care ◽  
Lung Tissue ◽  
Russian Society ◽  
Lung Pathology ◽  
Consensus Guidelines ◽  
X Ray ◽  
Ultrasound Diagnostics ◽  
Russian Association

The paper presents Consensus Guidelines of Russian Society of Radiology (RSR) and Russian Association of Specialists in Ultrasound Diagnostics in Medicine (RASUDM) «Role of imaging (X-ray, CT and US) in diagnosis of COVID-19 pneumonia» (version 2) of the Russian Society of Radiology and the Russian Association of Specialists in Ultrasound Diagnostics in Medicine.The guidelines list radiological techniques for lung diseases, which are used in coronavirus COVID-19 infection (chest X-ray, lung computed tomography (CT), and lung ultrasound (US), diagnostic algorithm, and follow-up study. The guidelines propose the models of the work of radiological rooms/departments of a healthcare facility, the procedure for conducting an examination, and recommendations for providing a description and assessing changes in the lung and chest in existing/suspected COVID-19-related pneumonia and present the schemes of X-ray and CT protocols at the initial examination and assessment of the changes.Chest X-ray has a low sensitivity for detecting initial changes in the first days of the disease and is not recommended for early diagnosis. Mobile radiography is an important tool for diagnosis of lung pathology in the intensive care units.CT is the most sensitive technique in detecting lung changes characteristic of COVID-19-related pneumonia. It is advisable to use CT for the initial evaluation of thoracic organs in patients with severe and progressive forms of the disease, as well as for the differential diagnosis and follow up.Lung US in patients with suspected/known COVID-19-related pneumonia is an additional imaging method that does not replace or exclude X-ray and CT. If the correct procedure is followed, correct indications are selected, and trained medical personnel is available, this study is highly sensitive in detecting interstitial changes and consolidations in lung tissue, but only in their subpleural location. The US data do not always allow definite determination of the reasons for the occurrence and/or actual extent of lung tissue changes.Standard reporting guidelines (CT, X-ray) about the possibility of COVID-19 pneumonia and its severity should be used.The follow up using CT, X-ray, or US depends on the clinical indications that necessitate dynamic assessment. The recommended frequency of repeat CT and X-ray in patients having no substantial changes in their clinical condition outside the intensive care units is not more than once every 5-7 days. An objective assessment of the time course of changes is possible only when comparing the data of the same type of study.

scholarly journals Role of ultra low dose CTKUB in follow-up of ureteric calculi not visible on plain X-ray

2016 ◽  
Vol 36 ◽  
pp. S124
Author(s):  
C. Jelley ◽  
L. Forster ◽  
J. Arad ◽  
G.S. Mudhar ◽  
H. Bardgett ◽  
...  
Keyword(s):  
Low Dose ◽  
X Ray ◽  
Ureteric Calculi

scholarly journals COVID-19 pneumonia: current evidence of chest imaging features, evolution and prognosis

2021 ◽  
Author(s):  
Anna Rita Larici ◽  
Giuseppe Cicchetti ◽  
Riccardo Marano ◽  
Lorenzo Bonomo ◽  
Maria Luigia Storto
Keyword(s):  
Current Knowledge ◽  
Current Evidence ◽  
Imaging Features ◽  
Chest Imaging ◽  
High Resolution Computed Tomography ◽  
X Ray ◽  
Prognostic Assessment ◽  
Patient’S Outcome

AbstractCOVID-19 pneumonia represents a global threatening disease, especially in severe cases. Chest imaging, with X-ray and high-resolution computed tomography (HRCT), plays an important role in the initial evaluation and follow-up of patients with COVID-19 pneumonia. Chest imaging can also help in assessing disease severity and in predicting patient’s outcome, either as an independent factor or in combination with clinical and laboratory features. This review highlights the current knowledge of imaging features of COVID-19 pneumonia and their temporal evolution over time, and provides recent evidences on the role of chest imaging in the prognostic assessment of the disease.

Scheduling strategies for the ESPRESSO follow-up of TESS targets

2021 ◽  
Vol 503 (4) ◽  
pp. 5504-5521
Author(s):  
L Cabona ◽  
P T P Viana ◽  
M Landoni ◽  
J P Faria
Keyword(s):  
Radial Velocity ◽  
Planetary Systems ◽  
Data Set ◽  
Noise Component ◽  
Orbital Parameters ◽  
Transiting Planets ◽  
Accuracy And Precision ◽  
Scheduling Strategies ◽  
The Masses

ABSTRACT Radial-velocity follow-up of stars harbouring transiting planets detected by TESS is expected to require very large amounts of expensive telescope time in the next few years. Therefore, scheduling strategies should be implemented to maximize the amount of information gathered about the target planetary systems. We consider myopic and non-myopic versions of a novel uniform-in-phase scheduler, as well as a random scheduler, and compare these scheduling strategies with respect to the bias, accuracy and precision achieved in recovering the mass and orbital parameters of transiting and non-transiting planets. This comparison is carried out based on realistic simulations of radial-velocity follow-up with ESPRESSO of a sample of 50 TESS target stars, with simulated planetary systems containing at least one transiting planet with a radius below 4R⊕. Radial-velocity data sets were generated under reasonable assumptions about their noise component, including that resulting from stellar activity, and analysed using a fully Bayesian methodology. We find the random scheduler leads to a more biased, less accurate, and less precise, estimation of the mass of the transiting exoplanets. No significant differences are found between the results of the myopic and non-myopic implementations of the uniform-in-phase scheduler. With only about 22 radial velocity measurements per data set, our novel uniform-in-phase scheduler enables an unbiased (at the level of 1 per cent) measurement of the masses of the transiting planets, while keeping the average relative accuracy and precision around 16 per cent and 23 per cent, respectively. The number of non-transiting planets detected is similar for all the scheduling strategies considered, as well as the bias, accuracy and precision with which their masses and orbital parameters are recovered.

The Role of Chest X-Ray in the Follow-Up of Primary Breast Cancer

1983 ◽  
Vol 69 (2) ◽  
pp. 151-154 ◽  
Author(s):  
Stefano Ciatto ◽  
Andrea Herd-Smith
Keyword(s):  
Breast Cancer ◽  
Randomized Study ◽  
Breast Cancer Patients ◽  
X Ray ◽  
History Of ◽  
Small Gain ◽  
Chest X Ray ◽  
Phase Out

The results of chest X-ray (CXR) survey in the follow-up of 1697 breast cancer patients are reviewed. Intrathoracic metastases (ITM) accounted for 26% of total first recurrences, but the rate dropped to 13% if isolated ITM and to 7% if asymptomatic isolated ITM were considered. Thus the role of CXR survey was limited to the detection of 39 cases of isolated ITM in the asympatomatic phase out of 7100 patients-year for a total number of 11,543 CXR examinations. Moreover, no difference in mean survival was observed if symptomatic and asymptomatic ITM were considered and survival was calculated from the time of first treatment. A small gain of 3 months, not statistically significant, of mean life from metastases diagnosis was recorded for asymptomatic cases, which is probably entirely due to the lead time effect of anticipated diagnosis. CXR survey in breast cancer follow-up may add to the knowledge of the natural history of the disease, but it appears worthless for other purposes. Thus the high costs related to CXR survey may be unacceptable, and a randomized study on the role of CXR is suggested and justified.

scholarly journals Brown dwarf companion with a period of 4.6 yr interacting with the hot Jupiter CoRoT-20 b

2018 ◽  
Vol 619 ◽  
pp. A115 ◽  
Author(s):  
J. Rey ◽  
F. Bouchy ◽  
M. Stalport ◽  
M. Deleuil ◽  
G. Hébrard ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Parameter Space ◽  
Minimum Mass ◽  
Orbital Eccentricity ◽  
Brown Dwarf ◽  
Migration Mechanism ◽  
Hot Jupiter

We report the discovery of an additional substellar companion in the CoRoT-20 system based on six years of HARPS and SOPHIE radial velocity follow-up. CoRoT-20 c has a minimum mass of 17 ± 1 MJup and orbits the host star in 4.59 ± 0.05 yr, with an orbital eccentricity of 0.60 ± 0.03. This is the first identified system with an eccentric hot Jupiter and an eccentric massive companion. The discovery of the latter might be an indication of the migration mechanism of the hot Jupiter, via the Lidov–Kozai effect. We explore the parameter space to determine which configurations would trigger this type of interactions.

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