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The gravitational wave detectors have shown a population of massive black holes that do not resemble those observed in the Milky Way 1 – 3 and whose origin is debated 4 – 6 . According to a possible explanation, these black holes may have formed from density fluctuations in the early Universe (primordial black holes) 7 – 9 , and they should comprise several to 100% of dark matter to explain the observed black hole merger rates 10 – 12 . If these black holes existed in the Milky Way dark matter halo, they would cause long-timescale gravitational microlensing events lasting years 13 . The previous experiments were not sufficiently sensitive to such events 14 – 17 . Here we present the results of the search for long-timescale microlensing events among the light curves of nearly 80 million stars located in the Large Magellanic Cloud that were monitored for 20 years by the Optical Gravitational Lensing Experiment survey 18 . We did not find any events with timescales longer than 1 year, whereas all shorter events detected may be explained by known stellar populations. We find that compact objects in the mass range from 1.8 × 10 −4 M ⊙ to 6.3 M ⊙ cannot make up more than 1% of dark matter, and those in the mass range from 1.3 × 10 −5 M ⊙ to 860  M ⊙ cannot make up more than 10% of dark matter. Thus, primordial black holes in this mass range cannot simultaneously explain a substantial fraction of dark matter and gravitational wave events. The results of the search for long-timescale microlensing events among the light curves of nearly 80 million stars located in the Large Magellanic Cloud indicate that there are no massive black holes in the Milky Way halo.

Stellar-mass black holes are the final remnants of stars born with more than 15 solar masses. Billions are expected to reside in the Local Group, yet only a few are known, mostly detected through X-rays emitted as they accrete material from a companion star. Here, we report on VFTS 243: a massive X-ray-faint binary in the Large Magellanic Cloud. With an orbital period of 10.4 d, it comprises an O-type star of 25 solar masses and an unseen companion of at least nine solar masses. Our spectral analysis excludes a non-degenerate companion at a 5 σ confidence level. The minimum companion mass implies that it is a black hole. No other X-ray-quiet black hole is unambiguously known outside our Galaxy. The (near-)circular orbit and kinematics of VFTS 243 imply that the collapse of the progenitor into a black hole was associated with little or no ejected material or black-hole kick. Identifying such unique binaries substantially impacts the predicted rates of gravitational-wave detections and properties of core-collapse supernovae across the cosmos. An inactive black hole has been found in the Large Magellanic Cloud, bound into a binary star system. Having experienced a negligible ‘kick’ during formation, the existence of this black hole has strong implications for black hole-–black hole mergers.

Premature ovarian insufficiency (POI) is defined as a cessation of ovarian function before the age of 40. Such early deprivation of estrogens in women may be associated with several adverse cardiovascular and metabolic consequences. The aim of this retrospective study was to investigate whether women with POI and a serum follicle-stimulating hormone (FSH) level of 25–40 I/U (Group A) have the same metabolic profile as women with POI and a serum FSH level of >40 I/U (Group B). One hundred twenty-three women were included in the study group (Group A; n = 41; Group B; n = 82). The control group comprised 77 healthy women with regular menstruation. In the age- and BMI-adjusted model, no differences were found between the groups with respect to total cholesterol, high-density lipoproteins, triglycerides, HOMA-IR, glucose, and insulin. The only significant difference was found in terms of low-density lipoprotein cholesterol (LDL-C). The highest serum concentration was found in Group B, the second highest was found in Group A, and the lowest was in the controls. In conclusion, changing the threshold of FSH required to establish a POI diagnosis may have an impact on the level of serum LDL-C.

In modern astronomy, the quantity of data collected has vastly exceeded the capacity for manual analysis, necessitating the use of advanced artificial intelligence (AI) techniques to assist scientists with the most labor-intensive tasks. AI can optimize simulation codes where computational bottlenecks arise from the time required to generate forward models. One such example is PHOEBE, a modeling code for eclipsing binaries (EBs), where simulating individual systems is feasible, but analyzing observables for extensive parameter combinations is highly time-consuming. To address this, we present a fully connected feedforward artificial neural network (ANN) trained on a dataset of over one million synthetic light curves generated with PHOEBE. Optimization of the ANN architecture yielded a model with six hidden layers, each containing 512 nodes, provides an optimized balance between accuracy and computational complexity. Extensive testing enabled us to establish ANN's applicability limits and to quantify the systematic and statistical errors associated with using such networks for EB analysis. Our findings demonstrate the critical role of dilution effects in parameter estimation for EBs, and we outline methods to incorporate these effects in AI-based models. This proposed ANN framework enables a speedup of over four orders of magnitude compared to traditional methods, with systematic errors not exceeding 1\\%, and often as low as 0.01\\%, across the entire parameter space.

We present an analysis of 991 heartbeat stars (HBSs) from the OGLE Collection of Variable Stars (OCVS). The sample consists of 512 objects located toward the Galactic bulge (GB), 439 in the Large Magellanic Cloud (LMC) and 40 in the Small Magellanic Cloud (SMC). We model the \\(I\\)-band OGLE light curves using an analytical model of flux variations, reflecting tidal deformations between stars. We present distributions of the model parameters that include the eccentricity, orbital inclination, and argument of the periastron, but also the period-amplitude diagrams. On the Hertzsprung-Russell (HR) diagram, our HBS sample forms two separate groups of different evolutionary status. The first group of about 90 systems, with short orbital periods (\\(P\\lesssim50\\)~days), consists of an early-type primary star lying on (or close to) the main sequence (MS). The second group of about 900 systems, with long orbital periods (\\(P\\gtrsim100\\)~days), contains a red giant (RG). The position of RG HBSs on the period-luminosity diagram strongly indicates their binary nature. They appear to be a natural extension of confirmed binary systems that include the OGLE ellipsoidal and Long Secondary Period (LSP) variables. We also present a time-series analysis leading to detection of tidally-excited oscillations (TEOs). We identify such pulsations in about 5\\% of stars in the sample with a total number of 78 different modes. This first relatively large homogeneous sample of TEOs allowed us to construct a diagram revealing the correlation between the TEO's orbital harmonic number and the eccentricity of the host binary system.

Observations of the Galactic bulge revealed an excess of short-timescale gravitational microlensing events that are generally attributed to a large population of free-floating or wide-orbit exoplanets. However, in recent years, some authors suggested that planetary-mass primordial black holes (PBHs) comprising a substantial fraction (1%-10%) of the dark matter in the Milky Way may be responsible for these events. If that was the case, a large number of short-timescale microlensing events should also be seen toward the Magellanic Clouds. Here, we report the results of a high-cadence survey of the Magellanic Clouds carried out from 2022 October through 2024 May as part of the Optical Gravitational Lensing Experiment. We observed almost 35 million source stars located in the central regions of the Large and Small Magellanic Clouds and found only one long-timescale microlensing event candidate. No short-timescale events were detected despite high sensitivity to such events. That allows us to infer the strongest available limits on the frequency of planetary-mass PBHs in dark matter. We find that PBHs and other compact objects with masses from \\(1.4 \\times 10^{-8}\\,M_{\\odot}\\) (half of the Moon mass) to \\(0.013\\,M_{\\odot}\\) (planet/brown dwarf boundary) may comprise at most 1% of dark matter. That rules out the PBH origin hypothesis for the short-timescale events detected toward the Galactic bulge and indicates they are caused by the population of free-floating or wide-orbit planets.

Uterine serous carcinoma (USC) is an uncommon but aggressive type of endometrial cancer associated with rapid progression of disease and a poor prognosis. The morphological and clinical features of the typical USC have been well delineated, but its precursor lesion is still under debate in terms of morphology as well as terminology. The putative precursor lesion of USC previously designated as endometrial intraepithelial carcinoma (EIC) or endometrial adenocarcinoma in situ or uterine surface carcinoma is now being referred to as serous EIC. Serous EIC is defined morphologically as replacement of endometrial surface epithelium and glands by frankly malignant cells that resemble the cells of the invasive high-grade endometrial carcinoma. Serous EIC is commonly associated with extrauterine serous carcinoma. Therefore it may be an early form of cancer rather than a precursor lesion. Endometrial glandular dysplasia (EmGD) is a newly defined entity that is commonly and specifically associated with serous EIC and USC. It has been proposed as a true precancerous lesion of USC based on recent studies showing morphological and molecular linkages between these 2 lesions.

According to our observations and data from the literature, vaginitis, vulvitis and cervitis are among the commonest issues found in outpatient gynaecological practice. Senescence of the human population, an increase in the number of women after menopause, the frequent use of hormone replacement therapy and therapeutic agents, and increasing incidence of systemic diseases make the problem very common in postmenopausal women.

The aim of the study was to present a new EIN classification of premalignant endometrial lesions. The diagnosis of precancerous disease of the endometrium remains non-standardized because the most widely used World Health Organisation classification is a poorly reproducible system, which does not specify objective architectural criteria for each category of hyperplasia and does not correspond to appropriate clinical management (undertreatment, overtreatment of the lesions). The new proposed EIN diagnostic schema, based on integrated morphological, genetic molecular, objective histomorphometric (D-score) and clinical outcome studies, divides endometrial lesions into three categories: benign hyperplasia, endometrial intraepithelial neoplasia, and cancer.

Some accreting binary systems containing a white dwarf (such as classical novae or persistent supersoft sources) are seen to emit low-energy X-rays with temperatures of ~10^6 K and luminosities exceeding 10^35 erg/s. These X-rays are thought to originate from nuclear burning on the white dwarf surface, either caused by a thermonuclear runaway (classical novae) or a high mass-accretion rate that sustains steady nuclear burning (persistent sources). The discovery of transient supersoft X-rays from ASASSN-16oh challenged these ideas, as no clear signatures of mass ejection indicative of a classical nova eruption were detected, and the origin of these X-rays remains controversial. It was unclear whether this star was one of a kind or representative of a larger, as yet undiscovered, group. Here, we present the discovery of 29 stars located in the direction of the Magellanic Clouds exhibiting long-duration, symmetrical optical outbursts similar to that seen in ASASSN-16oh. We observed one of these objects during an optical outburst and found it to be emitting transient supersoft X-rays, while no signatures of mass ejection (indicative of a classical nova eruption) were detected. We therefore propose that these objects form a homogeneous group of transient supersoft X-ray sources, which we dub ``millinovae'' because their optical luminosities are approximately a thousand times fainter than those of ordinary classical novae.