A rotating white dwarf shows different compositions on its opposite faces.

White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink towards the centre and the upper layer of the atmosphere contains only the lightest element present, usually hydrogen or helium1,2. Several mechanisms compete with gravitational settling to change a white dwarf's surface composition as it cools3, and the fraction of white dwarfs with helium atmospheres is known to increase by a factor of about 2.5 below a temperature of about 30,000 kelvin4-8; therefore, some white dwarfs that appear to have hydrogen-dominated atmospheres above 30,000 kelvin are bound to transition to be helium-dominated as they cool below it. Here we report observations of ZTF J203349.8+322901.1, a transitioning white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. This peculiar nature is probably caused by the presence of a small magnetic field, which creates an inhomogeneity in temperature, pressure or mixing strength over the surface9-11. ZTF J203349.8+322901.1 might be the most extreme member of a class of magnetic, transitioning white dwarfs-together with GD 323 (ref. 12), a white dwarf that shows similar but much more subtle variations. This class of white dwarfs could help shed light on the physical mechanisms behind the spectral evolution of white dwarfs.

Radiofrequency as a method of localizing impalpable breast lesions.

BACKGROUND: The incidence of early stage breast cancer has risen as a result of increased detection of non-palpable tumors through the implementation of screening programs and greater public awareness. Performing breast-conserving surgery can be challenging due to the need for accurate localization of non-palpable breast lesions, particularly given the logistical difficulties associated with wire localization. After implementing a new technique for localizing non-palpable breast lesions (LOCalizerTM Radiofrequency identification TAG-Hologic®), a radiofrequency identification tag localization device manufactured by Hologic, Inc. in Marlborough, MA, was launched in 2017, our objective was to investigate its impact on surgical outcomes, whether there was an increase in re-excision rates for positive margins and whether the attainment of clear margins was dependent on the exact positioning of the RFID device. METHOD: A single-center single-arm interventional study, data were gathered both in a forward-looking manner for 1 year (prospectively) and by looking back at past records for 1 year (retrospectively) for a total period of two years. Individuals who were diagnosed with non-palpable breast lesions, as confirmed by histological analysis, or invasive breast cancer and who were scheduled to undergo breast-conserving surgery were eligible for inclusion in the study. The RFID (Radiofrequency Identification) method was used to localize the lesions prior to surgery. Either with a mammogram or ultrasound scan position of the Tag was recorded, including the distance of the lesion from the center of the lesion and the lesion depth from the skin in millimeters. The rate of re-excision was documented and examined in relation to the parameters mentioned above. RESULTS: Two hundred and twenty RFID Tags were inserted in two hundred and seventeen (three patient had bilateral tags insertion), patients aged between 30 and 85 had a localizer Tag inserted between Oct 2020 and Oct 2022. Three patients had non-palpable breast lesions in both breasts. Fourteen were inserted under stereotactic guidance and two hundred and six under ultrasound guidance. Ten patients subsequently had wire insertion also due to Tag position. Of 210 procedures, RFIF Tags within the lesion was seen in hundred and sixty patients (76.19 %). An additional 50 procedures were performed using the RFID Tag system, which were not directly related to the lesion but were deemed appropriate to proceed with. Out of a total of 220 procedures, positive margins were observed in 38 cases (17.27 %). Among these cases, eleven (28.94 %) involved the use of the RFID Tag system, not within the lesion but adjacent to it (within 15 mm surrounding the lesion). CONCLUSION: RFID is a good alternative to wire localization of non-palpable breast lesions. Re-excision rates are higher in patients with Tag outside the lesion compared to those with Tag within the lesion.

Detection of Bonamia exitiosa (Haplosporidia) in European flat oysters Ostrea edulis cultivated in mainland Britain.

Following a reported mortality event of European flat oysters Ostrea edulis in southwestern England in December 2010, a sample of 30 oysters was examined using histology and molecular techniques. Histological examination of the oysters revealed the presence of microcell stages in the haemocytes and connective tissues of 3 out of the 30 animals examined. One animal showing marked haemocyte infiltration of the connective tissues was considered to be infected with Bonamia ostreae based on the presence of small uninucleate microcells measuring approximately 1 to 1.5 µm in diameter. Two other oysters were considered by histology to be infected with B. exitiosa. Infected haemocytes contained up to 5 microcells, measuring approximately 2 to 3 µm in diameter with a central or subcentral nucleus. Rarely, larger plasmodia-like multinucleated stages were noted in the haemocyte cytoplasm characterised by its irregular shape and increased eosinophilic cytoplasm. Haemocyte infiltration of the connective tissues surrounding the digestive gland and the mantle was noted along with necrosis of the tissues associated with the infection. Molecular analysis of the infected animals confirmed the presence of B. exitiosa in the sample. This study describes the parasite from flat oysters cultured in the UK; subsequent targeted sampling has not detected the parasite in flat oyster populations at this or other sites within the UK.