A dusty veil shading Betelgeuse during its Great Dimming.

Red supergiants are the most common final evolutionary stage of stars that have initial masses between 8 and 35 times that of the Sun1. During this stage, which lasts roughly 100,000 years1, red supergiants experience substantial mass loss. However, the mechanism for this mass loss is unknown2. Mass loss may affect the evolutionary path, collapse and future supernova light curve3 of a red supergiant, and its ultimate fate as either a neutron star or a black hole4. From November 2019 to March 2020, Betelgeuse-the second-closest red supergiant to Earth (roughly 220 parsecs, or 724 light years, away)5,6-experienced a historic dimming of its visible brightness. Usually having an apparent magnitude between 0.1 and 1.0, its visual brightness decreased to 1.614 ± 0.008 magnitudes around 7-13 February 20207-an event referred to as Betelgeuse's Great Dimming. Here we report high-angular-resolution observations showing that the southern hemisphere of Betelgeuse was ten times darker than usual in the visible spectrum during its Great Dimming. Observations and modelling support a scenario in which a dust clump formed recently in the vicinity of the star, owing to a local temperature decrease in a cool patch that appeared on the photosphere. The directly imaged brightness variations of Betelgeuse evolved on a timescale of weeks. Our findings suggest that a component of mass loss from red supergiants8 is inhomogeneous, linked to a very contrasted and rapidly changing photosphere.

Large granulation cells on the surface of the giant star π1 Gruis.

Convection plays a major part in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars, in dust clouds and on brown dwarfs. Most of our knowledge about stellar convection has come from studying the Sun: about two million convective cells with typical sizes of around 2,000 kilometres across are present on the surface of the Sun-a phenomenon known as granulation. But on the surfaces of giant and supergiant stars there should be only a few large (several tens of thousands of times larger than those on the Sun) convective cells, owing to low surface gravity. Deriving the characteristic properties of convection (such as granule size and contrast) for the most evolved giant and supergiant stars is challenging because their photospheres are obscured by dust, which partially masks the convective patterns. These properties can be inferred from geometric model fitting, but this indirect method does not provide information about the physical origin of the convective cells. Here we report interferometric images of the surface of the evolved giant star π1 Gruis, of spectral type S5,7. Our images show a nearly circular, dust-free atmosphere, which is very compact and only weakly affected by molecular opacity. We find that the stellar surface has a complex convective pattern with an average intensity contrast of 12 per cent, which increases towards shorter wavelengths. We derive a characteristic horizontal granule size of about 1.2 × 1011 metres, which corresponds to 27 per cent of the diameter of the star. Our measurements fall along the scaling relations between granule size, effective temperature and surface gravity that are predicted by simulations of stellar surface convection.

First Experimental Characterization of Microwave Emission from Cosmic Ray Air Showers.

We report the first direct measurement of the overall characteristics of microwave radio emission from extensive air showers. Using a trigger provided by the KASCADE-Grande air shower array, the signals of the microwave antennas of the Cosmic-Ray Observation via Microwave Emission experiment have been read out and searched for signatures of radio emission by high-energy air showers in the GHz frequency range. Microwave signals have been detected for more than 30 showers with energies above 3×10^{16} eV. The observations presented in this Letter are consistent with a mainly forward-directed and polarized emission process in the GHz frequency range. The measurements show that microwave radiation offers a new means of studying air showers at E≥10^{17} eV.

Kneelike structure in the spectrum of the heavy component of cosmic rays observed with KASCADE-Grande.

We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about 8×10(16) eV. This structure is also seen in the all-particle energy spectrum, but is less significant. Whereas the "knee" of the cosmic ray spectrum at 3-5×10(15) eV was assigned to light primary masses by the KASCADE experiment, the new structure found by the KASCADE-Grande experiment is caused by heavy primaries. The result is obtained by independent measurements of the charged particle and muon components of the secondary particles of extensive air showers in the primary energy range of 10(16) to 10(18) eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables.

Detection and imaging of atmospheric radio flashes from cosmic ray air showers.

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.

Adenoma sebáceo en un paciente con síndrome de Muir-Torre / Sebaceous adenoma in a patient with a Muir-Torre syndrome

El síndrome de Muir-Torre comprende la asociación de uno o más tumores de glándulas sebáceas, con una o más malignidades internas y antecedentes familiares de neoplasias. Presentamos el caso de un paciente masculino de 33 años, con antecedentes familiares de cáncer de colon, que consulta a nuestro servicio por lesión en cuero cabelludo de seis meses de evolución, con posterior diagnóstico histopatológico de adenoma sebáceo. Dentro de los exámenes complementarios se observan por colonoscopía, dos lesiones que correspondieron a adenocarcinomas de colon bien diferenciados. Con los antecedentes familiares, el examen clínico y la histopatología se efectúa el diagnóstico de síndrome de Muir-Torre.

Muir-Torre syndrome represents the association of one or more sebaceous tumors, with one or more visceral malignancies and a family history of cancer. We report the case of a 33-year-old man, with a family history of colon cancer, who presented with a scalp tumor. The histopathological diagnosis was sebaceous adenoma. Two lesions were found in the colonoscopy, which corresponded to colon adenocarcionomas. With a compatible personal and family history of cancer and the results of the histopathology, we diagnosed the patient as Muir-Torre syndrome.

Leishmaniasis mucocutánea con afectación laríngea / Mucocutaneous leishmaniasis with laryngeal involvement

La leishmaniasis es la infección producida por protozoos del género Leishmania. Presenta diferentes formas clínicas, dentro de las cuales, la leishmaniasis mucocutánea es una de las que conlleva mayor gravedad debido al compromiso de la vía aérea superior, que puede producir secuelas incapacitantes e incluso la muerte. Presentamos el caso de un paciente con diagnóstico de leishmaniasis mucocutánea con importante compromiso laríngeo, el cual tuvo excelente respuesta al tratamiento con antimoniales pentavalentes (AU)

Leishmaniasis is an infection caused by protozoa of the genus Leishmania. Mucocutaneous leishmaniasis is one of the clinical forms that presents more severity, due to the involvement of the upper airway, which can lead to incapacitating consequences or even death. We report the case of a patient with diagnosis of mucocutaneous leishmaniasis with significant laryngeal involvement which had excellent response to treatment with pentavalent antimonials (AU)

Hidradenitis supurativa con transformación carcinomatosa / Suppurative hidradenitis with carcinomatous transformation

La Hidradenitis Supurativa o Enfermedad de Verneuil es un proceso inflamatorio crónico, recurrente que afecta las glándulas apócrinas de axila, ingle, periné, cuero cabelludo y región anoperineal. Se desconoce la etiología precisa. Es una enfermedad poco frecuente, mal diagnosticada, se estima la incidencia en 1 cada 300 adultos. Afecta más a mujeres y personas de raza negra, sin embargo la enfermedad de localización perianal afecta más a varones. El tratamiento médico mitigaría los síntomas pero la mayoría de los pacientes presentan lesiones crónicas que requerirán tratamiento quirúrgico. El Carcinoma de Células Escamosas es una complicación rara vez informada que se desarrolla en las lesiones crónicas de Hidradenitis Supurativa de larga evolución. Presentamos un caso de un paciente de sexo masculino, de 51 años de edad, que presenta sobre antiguas lesiones cicatrizales formación tumoral multilobulada, ulcerada centralmente localizada en región glútea-perineal izquierda de 3 meses de evolución. Se realizaron métodos complementarios arribando al diagnóstico de Hidradenitis Supurativa con Transformación Carcinomatosa (Carcinoma de Células Escamosas). Se realizó tratamiento quirúrgico con posterior injerto cutáneo con excelente evolución. Motiva ésta presentación la localización infrecuente y la complicación inusual. Como dato relevante cabe destacar las escasas publicaciones sobre dicho tema (AU)

Hidradenitis Suppurativa or Verneuil's disease is a chronic inflammatory recurring process that affects the apocrine glands of the armpit, groin, perineal area, scalp and an operineal area. Its accurate ethiology is unknown. It is a rare disease, it is misdiagnosed and its incidence rate is estimated in 1 every 300 adults. It affects mainly women and black race people. However the perianal localization disease affects mainly men. The medical treatment would mitigate the symptoms but most patients have chronic lesions that would require surgical treatment. The squamous cell carcinoma is a rarely reported complication which develops in the chronic lesions of Hidradenitis Suppurativa of long-term evolution. We present a case of a male patient, 51 years old, who has, on old scar lesions, a centrally ulcerated multilobulated tumor formation of 3 months of evolution localized in the left gluteo-perineal area. Complementary methods were used which led to the diagnostics of Hydradernitis Suppurativa with Carcinomatose Transformation (Squamous cellcarcinoma). Surgical treatment followed by skin graft was used with excellent evolution. The reason for this presentation is the infrequent localization and the unusual complication. Something important to point out is that publications on this topic are rare (AU)

Dermatomicosis por Fusarium solani / Dermatomycosis by Fusarium solani

Se presenta el caso de un paciente de 76 años de edad, con lesiones cutáneas ocasionadas por Fusarium solani, agente oportunista que escasamente causa infección cutánea, no que se registran antecedentes en nuestra literatura. Se destacan las características remarcables de su acción patógena y la buena respuesta terapéutica con la utilización de 200 mg diarios de ketoconazol