Slowly fading super-luminous supernovae that are not pair-instability explosions.

Super-luminous supernovae that radiate more than 10(44) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of (56)Ni are synthesized; this isotope decays to (56)Fe via (56)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10(-6) times that of the core-collapse rate.

Prognostic factors of intraoperative accidental extubation during laryngeal surgeries.

Background: Head and neck surgery is considered high-risk for difficult intubation and accidental extubation. Laryngomicroscopy implies surgical manipulations at the level of the vocal cords. Also, this type of surgery demands a particular position for the patient during the whole surgical intervention. All of this makes accidental extubation even more possible. Methods: We included a total of 100 patients scheduled for laryngomicroscopy in the study. We have assessed patients' general and clinical data and provided necessary measurements. After the intubation, we documented the depth of the endotracheal tube at the level of the upper incisors and repeated the measurement after the surgical intervention. We recorded all possible difficulties encountered by the surgeon. Results: We found a significantly more frequent tube dislocation in patients from the difficult intubation group, with χ2 =6.632, p =0.010. Inter-incisor gap (IIG) and modified Mallampati score showed statistical significance regarding tube dislocation, with p values of 0.002 and 0.047, respectively. There was statistical significance between tube dislocation and difficulties experienced by surgeons, with χ2 =13.504 and p =0.001. According to the area under the curve (AUC) at the Receiver operating characteristic (ROC) curve, the cut-off value for significant tube dislocation was 1.15 cm. When we divided the enrolled patients into two groups, below and above the cut-off value, the IIG maintained statistical significance with a cut-off value of 5.25 cm. Conclusions: Modified Mallampati score and IIG are considered valuable parameters for rapid preoperative risk assessment of possible accidental extubation. The final depth of the endotracheal tube should be about two cm deeper than necessary, as long as there is adequate ventilation on both sides of the lungs. Difficult intubation undoubtedly represents a risk for accidental extubation occurrence. HIPPOKRATIA 2023, 27 (4):141-147.

X-Rays from the Location of the Double-humped Transient ASASSN-15lh.

We present the detection of persistent soft X-ray radiation with Lx ~ 1041-1042 erg s-1 at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, if the X-ray source is physically associated with the optical-UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event.

Ejection of the Massive Hydrogen-rich Envelope Timed with the Collapse of the Stripped SN 2014C.

We present multi-wavelength observations of SN 2014C during the first 500 days. These observations represent the first solid detection of a young extragalactic stripped-envelope SN out to high-energy X-rays ~40 keV. SN 2014C shows ordinary explosion parameters (Ek ~ 1.8 × 1051 erg and Mej ~ 1.7 M⊙). However, over an ~1 year timescale, SN 2014C evolved from an ordinary hydrogen-poor supernova into a strongly interacting, hydrogen-rich supernova, violating the traditional classification scheme of type-I versus type-II SNe. Signatures of the SN shock interaction with a dense medium are observed across the spectrum, from radio to hard X-rays, and revealed the presence of a massive shell of ~1 M⊙of hydrogen-rich material at ~6 × 1016 cm. The shell was ejected by the progenitor star in the decades to centuries before collapse. This result challenges current theories of massive star evolution, as it requires a physical mechanism responsible for the ejection of the deepest hydrogen layer of H-poor SN progenitors synchronized with the onset of stellar collapse. Theoretical investigations point at binary interactions and/or instabilities during the last nuclear burning stages as potential triggers of the highly time-dependent mass loss. We constrain these scenarios utilizing the sample of 183 SNe Ib/c with public radio observations. Our analysis identifies SN 2014C-like signatures in ~10% of SNe. This fraction is reasonably consistent with the expectation from the theory of recent envelope ejection due to binary evolution if the ejected material can survive in the close environment for 103-104 years. Alternatively, nuclear burning instabilities extending to core C-burning might play a critical role.

Is there a direct correlation between the duration and the treatment of type 2 diabetes mellitus and hearing loss?

AIM: The aim of the study was to determine the impact of the duration of diabetes and the control of glycemia on the auditory function of patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: This prospective study included 80 patients with T2DM (divided depending on when T2DM was diagnosed, and also according to the control of glycemia), and 50 healthy subjects. RESULTS: The hearing threshold in T2DM patients was statistically significantly higher for 1,000 Hz, 2,000 Hz, 4,000 Hz and 8,000 Hz. Absolute latencies of brainstem auditory evoked potentials (BAEP) revealed significant differences between average absolute latencies for waves I, III and V, as well as inter-wave latencies I‒V and I‒III (p <0.001). A statistically significant difference was noted in the presence of transitory otoacoustic emissions (TEOAE) (p <0.001). In T2DM patients with poor glycemic control, where the glycated hemoglobin (HbA1c) is above 7%, the hearing threshold levels were statistically significantly higher in both ears at 8,000 Hz and at 2,000 Hz in the right ear, and the absolute latency of wave V was prolonged in the right ear. There was no evidence that the duration of diabetes significantly affected the auditory threshold, absolute and inter-wave BAEP latencies. CONCLUSION: The patients with T2DM displayed an increased hearing threshold, qualitative changes in BAEP and the absence of TEOAE. The duration of poorly-controlled glycemia had a greater effect on the patients' auditory function than the duration of T2DM. Hippokratia 2016, 20(1): 32-37.

Severe dyspnea as atypical presenting symptom of Madelung's disease.

Madelung's disease (benign symmetrical lipomatosis) is a rare disease of unknown etiology manifesting as symmetric abnormal deposits of adipose tissue in the head, neck and upper trunk. We report a case of a 58-year-old man with a long lasting Madelungs disease in whom progressive fatty tissue accumulation caused a severe inspiratory dyspnea as atypical presenting symptom. The etiopathogenetic, clinico-diagnostic and therapeutic aspects of this rare disease are discussed. Due to its progressive but not so easily predictable enlarging behavior Madelung's disease has not only aesthetic but also functional and sometimes life threatening consequences which need to be treated.

Factors affecting results of treatment of Hypopharyngeal Carcinoma.

OBJECTIVE: A retrospective review of patients with malignant neoplasms of the hypopharynx treated with combined surgery and radiotherapy is presented to highlight the results of treatment and the factors of treatment success for this malignant disease. PATIENTS AND METHODS: Between 1995 and 2004 at the University ORL Clinic Nis 89 patients with malignant neoplasms of hypopharynx (85 males, 4 females, and age ranging from 44 to 77 years) were treated. In the 89 patients (stage I, n=4; stage II, n=3; stage III, n=34; stage IV, n=48), the sites of origin were pyriform sinus (n=75), postcrycoid (n=8), posterior pharyngeal wall (n=3) and superior hypopharynx (n=3). RESULTS: Laryngeal preservation surgery was achieved in 11.2% of patients, while 88.8% had laryngectomy with partial or total pharyngectomy. Pyriform sinus was the most common site of origin of hypopharyngeal carcinoma in 84.3%. Totally 93% of patients had neck metastases, and tumors extended beyond the hypopharynx in 41.6% of patients. TNM stage was highly significant parameter of outcome. Five year survival was 100% for stage I, 66.6% for stage II, 53.9% for stage III, and 33.3% for stage IV. Residual disease (5.6%) and recurrent disease (2.2%) were low. Postoperative fistula developed in 16.8% of patients, and in 60% it was closed successfully using local flaps, while in 40% pectoralis flap was needed. Localization of disease was also an important factor of survival. Retrocrycoid carcinoma resulted in very poor survival rate (12.5%), high residual disease, lymph node metastasis, and pharyngocutaneous fistula formation. CONCLUSION: Localization and TNM stage are highly significant factors for clinical course, treatment, and outcome of hypopharyngeal carcinoma.

Linfangioma cavernoso laringofaríngeo extenso causante de obstrucción de las vías aéreas superiores / Extensive laryngopharyngeal cavernous lymphangioma causing upper airway obstruction

No disponible