Detection of Na, K, and H2O in the hazy atmosphere of WASP-6b

ABSTRACT We present new observations of the transmission spectrum of the hot Jupiter WASP-6b both from the ground with the Very Large Telescope FOcal Reducer and Spectrograph (FORS2) from 0.45 to 0.83 μm, and space with the Transiting Exoplanet Survey Satellite from 0.6 to 1.0 μm and the Hubble Space Telescope (HST) Wide Field Camera 3 from 1.12 to 1.65 μm. Archival data from the HST Space Telescope Imaging Spectrograph (STIS) and Spitzer are also re-analysed on a common Gaussian process framework, of which the STIS data show a good overall agreement with the overlapping FORS2 data. We also explore the effects of stellar heterogeneity on our observations and its resulting implications towards determining the atmospheric characteristics of WASP-6b. Independent of our assumptions for the level of stellar heterogeneity we detect Na i, K i, and H2O absorption features and constrain the elemental oxygen abundance to a value of [O/H] ≃ −0.9 ± 0.3 relative to solar. In contrast, we find that the stellar heterogeneity correction can have significant effects on the retrieved distributions of the [Na/H] and [K/H] abundances, primarily through its degeneracy with the sloping optical opacity of scattering haze species within the atmosphere. Our results also show that despite this presence of haze, WASP-6b remains a favourable object for future atmospheric characterization with upcoming missions such as the James Webb Space Telescope.

Combating acoustic heterogeneity in photoacoustic computed tomography: A review

Based on the energy conversion of light into sound, photoacoustic computed tomography (PACT) is an emerging biomedical imaging modality and has unique applications in a range of biomedical fields. In PACT, image formation relies on a process called acoustic inversion from received photoacoustic signals. While most PACT systems perform this inversion with a basic assumption that biological tissues are acoustically homogeneous, the community gradually realizes that the intrinsic acoustic heterogeneity of tissues could pose distortions and artifacts to finally formed images. This paper surveys the most recent research progress on acoustic heterogeneity correction in PACT. Four major strategies are reviewed in detail, including half-time or partial-time reconstruction, autofocus reconstruction by optimizing sound speed maps, joint reconstruction of optical absorption and sound speed maps, and ultrasound computed tomography (USCT) enhanced reconstruction. The correction of acoustic heterogeneity helps improve the imaging performance of PACT.

Early Clinical Outcome of the First Lung SBRT Program in Jordan: Importance of International Collaboration

Background: The stereotactic radiotherapy (SBRT) program was established at King Hussein Cancer Center (KHCC) in Jordan through cooperation with an internationally renowned institution MD Anderson Cancer Center (MDACC) in USA, and it went clinical in 2012. Until the present day, it stands as the only SBRT program in the entire country with patient population that has increased in the past few years due influx of refugees from regional conflicts. In this presentation, we will present the clinical outcome of our SBRT program. Methods: 17 patients treated to date in the SBRT service. All patients underwent 10-phase 4DCT and PET-CT scans. The internal target volume (ITV) was constructed from the minimum intensity projection (MIP) dataset and expanded, if needed, following PET findings. 5 mm margin added to create the PTV. A dose scheme of 48 Gy in 4 fractions or 50 Gy/4 fractions were used for all patients except for two patients who received 60 Gy in 8 fractions due to toxicity concerns. Lung heterogeneity correction was used during planning and treatment delivery was done on Elekta Precise Linear Accelerator and using CBCT imaging for positioning for every fraction. Follow- up done by performing CT chest 3 months after completion of SBRT, and CT/PET every 6 months in the two years, CT chest every 4-6 months thereafter, and keeping CT/PET whenever indicated. Results: All patients treated were males except one, with age ranging from 50-84 years old (mode of 79). All patients were unfit for surgery except for one who refused surgery. All patients except one are alive with only one patient recurred locally. One patient died not due to cancer. Conclusion: The newly established SBRT clinical service in our country, serves as the only such treatment of a population of 9.5 million including 2.5 million refugees. We have started recruiting inoperable lung patients to the service at a slow pace to gain more confidence and experience before admitting larger number of patients. Clinical results are encouraging with most showing tumor regression/complete response as of last follow-up. This model of collaboration between KHCC and MDACC represents a successful scientific collaboration between cancer centers in developed and developing countries that lead to effective and safe implementation of new techniques and procedures.

Heterogeneity correction for improved breast cancer ablation

The treatment of breast cancer by MR guided HIFU has recently shown great potential for clinical practice. Although innovative lateral firing transducer designs allow to significantly reduce the risk of undesired tissue damage to the thoracic cage, the heart and the lung, such a design is typically limited by the aberration effect of the inhomogeneous tissue composition of the breast. This project proposes a correction strategy for this type of aberrations, based on high resolution MRI in conjunction with tissue ultrasound celerity measurements. The method is compatible with clinical practice and has the potential to lead to improved treatment efficiency and increased patient safety for MR guided HIFU ablations of breast cancer.