Massive stars (initial mass ≳10M ⊙ , where M ⊙ is the mass of the Sun) end their life through violent explosions known as core-collapse supernovae, which are supposed to be among the brightest events ...of the universe. Nucleosynthesis inside the ejecta of such exploding stars was proposed to be the main source of its years-long radiated power. With the advent of timedomain astronomy, brilliant supernovae with longer evolutionary time scales and larger peak luminosities (10-100 times) than canonical supernovae, have been revealed. These are Superluminous Supernovae (SLSNe). The powering mechanisms of SLSNe are yet not resolved. The proposed theories are the interaction of SN-shock with circumstellar medium (CSM), the presence of a spindown magnetar, or pair-instability (PISNe) in very massive stars. Most likely, In the case of SLSNe, these physical processes generate extra radiated power in addition to the radioactive power due to explosive nucleosynthesis inside the ejecta. Here, I review different mechanisms behind the radiated luminosity of supernovae created from massive progenitors.
Abstract We present multiband follow-up observations of the supermassive binary black hole (BBH) candidate and misaligned double–double radio galaxy, J1328+2752. To investigate its parsec-scale ...structure, we have carried out observations with the Very Long Baseline Array (VLBA) and the European Very Long Baseline Interferometry (VLBI) Network. Additionally, we have obtained optical spectroscopic observations with the 3.6 m Devasthal Optical Telescope. Within 3.5 yr of our previous VLBI observations, the central parsec-scale radio structure of J1328+2752 has changed from a double component to a single central component and its flux density has increased by a factor of 3 in the 5 GHz VLBA observations. The new radio component is largely unresolved at 3, 5, and 8 GHz. The multifrequency radio data shows a convex-shaped spectrum for this unresolved component. The turnover frequency is at ∼3 GHz. While the total intensity image does not reveal any details, a super-resolved VLBA 5 and 8 GHz spectral index image does indicate the presence of two components at a separation of ∼4.2 pc with spectral indices −0.5 ± 0.3 and −0.9 ± 0.3. We have not observed a simultaneous change in the optical line profiles or intensities over the past few years. The radio structure, the variation of the flux density, and spectral shape can potentially be consistent both with the signature of a young radio source or a BBH at the center of J1328+2752.
Acute Zonal Occult Outer Retinopathy (AZOOR) is characterized by sudden visual impairment, often presenting with scotoma and photopsia in young to middle-aged adults, showing a female predominance. ...This condition, distinct from genetic disorders like retinitis pigmentosa, lacks a hereditary basis and exhibits unique fundus changes and imaging features indicative of outer retinal dysfunction. Recent advancements have broadened our understanding, identifying variants like Acute Annular Outer Retinopathy (AAOR) and Multizonal outer retinopathy and retinal pigment epitheliopathy (MORR), each with specific clinical presentations and imaging characteristics. The diagnosis of AZOOR and its variants primarily relies on excluding other conditions through comprehensive evaluation, including imaging and serological testing. Treatment approaches, including the use of corticosteroids and immunosuppressives, remain debated, with some evidence suggesting benefits in the early stages. The prognosis of AZOOR varies, with most patients experiencing stabilization, although complications like choroidal neovascularization may occur, requiring targeted therapy. This manuscript elucidates the complexity of AZOOR, emphasizing the necessity of high clinical suspicion and the role of advanced imaging in diagnosis and management.
The clinical characteristics of pachychoroid phenotype are reduced choroidal vascular markings in fundus, drusenoid retinal pigment epithelium (RPE) changes, and small pigment epithelium detachments. ...3 With the evolution of our knowledge about pachychoroid, it is now believed that the total thickness of choroid was not the sole criterion to define pachychoroid phenotype and eyes with choroidal thickness less than 300 micron too could manifest pathological changes of diseases associated with pachychoroid. The present study also reports pachydrusen as a feature of chronic, persistent or resolved CSC and not of acute CSC. It will be interesting to note pachydrusen in eyes with uncomplicated pachychoroid or pachychoroid pigment epitheliopathy which have not developed CSC. Similarly, a longitudinal study of pachydrusen in CSC will be able to shed light on their natural history, their influence on spontaneous resolution of CSC, as well as on the response to treatment.
Conventional High Intensity Focused Ultrasound (HIFU) is a therapeutic modality which is extracorporeally administered. In applications where a relatively small HIFU lesion is required, an ...intravascular HIFU probe can be deployed to the ablation site. In this paper, we demonstrate the design and implementation a fully integrated HIFU drive system on a chip to be placed on a 6 Fr catheter probe. An 8-element capacitive micromachined ultrasound transducer (CMUT) ring array of 2 mm diameter has been used as the ultrasound source. The driver chip is fabricated in 0.35 μm AMS high-voltage CMOS technology and comprises eight continuous-wave (CW) high-voltage CMUT drivers (10.9 ns and 9.4 ns rise and fall times at 20 V pp output into a 15 pF), an eight-channel digital beamformer (8-12 MHz output frequency with 11.25° phase accuracy) and a phase locked loop with an integrated VCO as a tunable clock source (128-192 MHz). The chip occupies 1.85 × 1.8 mm 2 area including input and output (I/O) pads. When the transducer array is immersed in sunflower oil and driven by the IC with eight 20 V pp CW pulses at 10 MHz, real-time thermal images of the HIFU beam indicate that the focal temperature rises by 16.8 °C in 11 seconds. Each HV driver consumes around 67 mW of power when driving the CMUT array at 10 MHz, which adds up to 560 mW for the whole chip. FEM based analysis reveals that the outer surface temperature of the catheter is expected to remain below the 42 °C tissue damage limit during therapy.
The transmit and receive sensitivity of the capacitive micromachined ultrasonic transducer (CMUT) is proportional to the active device capacitance formed by the vacuum gap of the device, and an ...insulation layer between the gap and the device electrode. In the sacrificial release process of CMUT fabrication, this insulation layer cannot be made arbitrarily thin due to conformality issues. In this paper, we propose and prove the applicability of a micromachining technique by which metallic sacrificial islands are embedded inside grooves etched on the substrate, yielding topology free surfaces. This obviates the conformality requirement, and enables the growth of a thinner insulation layer which reduces the effective gap height, and, hence, improves sensitivity. Embedded metalic layers, which provide a flat surface for subsequent process steps, have also been used as the back electrode of the CMUT, which facilitated the manufacturing of devices with reduced stray capacitance on thermally oxidized wafers. CMUT devices were fabricated using the proposed technique, and their parameters were measured to justify the performance improvement. While the dc bias requirement is reduced by 19%, the output sensitivity of the device is 10% higher than that of the conventional CMUT, and spurious capacitance is decreased by 70%.
Purpose: The aim of this study is to assess the ability of multicolour imaging (MCI) to detect foveal cysts in diabetic macular edema (DME) and compare it with conventional color fundus photography ...(CFP) and foveal autofluorescence (FAF) pattern. Methods: It was a retrospective review of 112 eyes of 84 DME patients with central foveal thickness ≥250 μ who underwent MCI, CFP and shortwave autofluorescence imaging. MCI was performed with Sepctralis spectral domain optical coherence tomography (SDOCT) (Heidelberg Engineering, Germany). Results: 97 (86.6%) eyes had cystoid increased autofluorescence (cystoid iFAF), 9 (8%) had spot iFAF and 6 (5.35%) had irregular decreased FAF (dFAF). Among eyes with cystoid iFAF, OCT detected DME cysts in 93 (95.6%) eyes, MCI in 75 (77.3%) and CFP in 5 (5.15%) eyes. In all these eyes, the location of cysts on OCT and MCI corresponded with the location of cystoid iFAF, whereas none of the eyes with cyst seen on CFP correlated with the location of cystoid iFAF. Conclusion: MCI was superior to CFP in detecting DME cysts at fovea. It also correlated with hyperautofluorescence pattern in these eyes. MCI may have a potential role in diabetic retinopathy screening by segregating eyes with DME which would require treatment. Our findings need to be further validated in a larger and prospective study design.
Purpose: To describe treatment outcomes of eyes with pachychoroid neovasculopathy (PNV) with PDT and anti-(vascular endothelial growth factor) VEGF therapy. Methods: Retrospective interventional case ...series. Records of six consecutive cases of PNV were reviewed. Four cases were treated with PDT+ inj ranibizumab. Two cases underwent only PDT. Final visual outcomes and functional outcome including macular status and choroidal thickness were assessed. Results: We analysed six eyes of six patients with PNV. There were four males and two females. Mean age of the patients was 56.5 years. Mean duration of follow up was 8.2 months. All patients received reduced fluence PDT. Four patients received ranibizumab along with PDT; mean BCVA at presentation was 0.41 log MAR units and mean BCVA at final follow up was 0.44 log MAR units. There was significant improvement at final follow up (P = 0.03). Mean subfoveal choroidal thickness (SFCT) at presentation was 445 microns and mean SFCT at final follow up was 293 microns. There was a significant reduction at final follow up (P = 0.02). Conclusion: PDT with or without ranibizumab appears to be an effective treatment modality for PNV.
Incorporation of SDOCT in all cases of Eales' disease in their clinic, irrespective of presence or absence of suggestive macular findings on slit-lamp biomicroscopy which would warrant an SDOCT scan ...is intriguing but does bring value to the report. Looking for macular edema in cases of retinal vasculitis is vital and is often not sought after because of continued focus of clinician on the peripheral retina; seeking changes such as retinal neovascularization and fibrovascular proliferation which would increase the risk of vitreous hemorrhage. Inflammation of the retinal vessels in Eales disease is the harbinger of chain of clinical events which range from vascular nonperfusion to neovascularization, vitreous hemorrhage, and tractional retinal detachment.
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