Collisions in a gas-rich white dwarf planetary debris disc

WD 0145+234 is a white dwarf that is accreting metals from a circumstellar disc of planetary material. It has exhibited a substantial and sustained increase in 3-5 [Formula: see text]m flux since 2018. Follow-up Spitzer photometry reveals that emission from the disc had begun to decrease by late 2019. Stochastic brightening events superimposed on the decline in brightness suggest the liberation of dust during collisional evolution of the circumstellar solids. A simple model is used to show that the observations are indeed consistent with ongoing collisions. Rare emission lines from circumstellar gas have been detected at this system, supporting the emerging picture of white dwarf debris discs as sites of collisional gas and dust production.

A giant planet candidate transiting a white dwarf

Astronomers have discovered thousands of planets outside the Solar System¹, most of which orbit stars that will eventually evolve into red giants and then into white dwarfs. During the red giant phase, any close-orbiting planets will be engulfed by the star², but more distant planets can survive this phase and remain in orbit around the white dwarf^3,4. Some white dwarfs show evidence for rocky material floating in their atmospheres⁵, in warm debris disks^6-9 or orbiting very closely^10-12, which has been interpreted as the debris of rocky planets that were scattered inwards and tidally disrupted¹³. Recently, the discovery of a gaseous debris disk with a composition similar to that of ice giant planets¹⁴ demonstrated that massive planets might also find their way into tight orbits around white dwarfs, but it is unclear whether these planets can survive the journey. So far, no intact planets have been detected in close orbits around white dwarfs. Here we report the observation of a giant planet candidate transiting the white dwarf WD 1856+534 (TIC 267574918) every 1.4 days. We observed and modelled the periodic dimming of the white dwarf caused by the planet candidate passing in front of the star in its orbit. The planet candidate is roughly the same size as Jupiter and is no more than 14 times as massive (with 95 per cent confidence). Other cases of white dwarfs with close brown dwarf or stellar companions are explained as the consequence of common-envelope evolution, wherein the original orbit is enveloped during the red giant phase and shrinks owing to friction. In this case, however, the long orbital period (compared with other white dwarfs with close brown dwarf or stellar companions) and low mass of the planet candidate make common-envelope evolution less likely. Instead, our findings for the WD 1856+534 system indicate that giant planets can be scattered into tight orbits without being tidally disrupted, motivating the search for smaller transiting planets around white dwarfs.

Interplay between synthetic conditions and micromorphology in poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos): an atomistic investigation

A systematic analysis was performed to elucidate the role played by proton scavengers in PEDOT chain length distribution and micromorphology.

Hepatic schistosomiasis with massive splenomegaly: a case report and literature review

Schistosomiasis is a parasitic disease caused by Schistosoma species. Intestinal and hepatic schistosomiases are the most common forms of chronic disease. We describe a case of a 26-year old patient from Eritrea who was referred to our hospital with abdominal pain and diarrhea. The diagnosis of hepatosplenic schistosomiasis was made by liver biopsy and the patient was treated with praziquantel. Hepatic schistosomiasis is characterised by deposition of schistosomal eggs in the liver which results in a host cell immune response and leads to granuloma formation and neoangiogenesis. This is hallmarked by different grades of periportal fibrosis with portal hypertension leading to splenomegaly. Normal liver architecture is preserved and periportal fibrosis can be reversible if treated adequately and timely. With a recent native schistosomiasis cluster report from France and the expected influx to Europe of persons from regions endemic for schistosomiasis, increased awareness of this disease in healthcare practitioners is needed. We review the epidemiology, pathogenesis, clinical presentation and treatment of schistosomiasis.

A VLBI resolution of the Pleiades distance controversy

Because of its proximity and its youth, the Pleiades open cluster of stars has been extensively studied and serves as a cornerstone for our understanding of the physical properties of young stars. This role is called into question by the "Pleiades distance controversy," wherein the cluster distance of 120.2 ± 1.5 parsecs (pc) as measured by the optical space astrometry mission Hipparcos is significantly different from the distance of 133.5 ± 1.2 pc derived with other techniques. We present an absolute trigonometric parallax distance measurement to the Pleiades cluster that uses very long baseline radio interferometry (VLBI). This distance of 136.2 ± 1.2 pc is the most accurate and precise yet presented for the cluster and is incompatible with the Hipparcos distance determination. Our results cement existing astrophysical models for Pleiades-age stars.

Dissection of the HLA association with multiple sclerosis in the founder isolated population of Sardinia

Several studies have indicated that multiple sclerosis (MS) is associated and linked to the major histocompatibility complex (MHC)/human leukocyte antigen (HLA) region of chromosome 6p21.3, but the exact location and nature of the primarily associated locus within the HLA complex is still controversial and largely presumptive. By linkage disequilibrium mapping, we have systematically investigated this chromosome region in the founder population of Sardinia to determine the relative associations of the various loci with MS. An overall 11.4 Mb region, which encompasses the whole HLA complex, was scanned with 19 microsatellite markers and with single nucleotide polymorphisms within 12 functional candidate genes and assessed for MS association using the extended transmission disequilibrium test (ETDT). A peak of association represented by the three adjacent DRB1, -DQA1 and -DQB1 loci was detected in the class II region. Two additional less significant areas of association were detected, respectively, in the centromeric side of the class II region at the DPB1 locus and, telomeric of the classically defined class I loci, at the D6S1683 microsatellite. Conditional ETDT analysis indicated that these regions of association could be independent of each other. Within the main peak of association, DRB1 and DQB1 contribute to the disease association independently of each other whereas DQA1 had no detectable primary genetic effects. We evaluated the haplotype distribution at the region showing the strongest association and found five DQB1-DRB1 haplotypes positively associated with MS in Sardinia. These consistently included all the haplotypes previously found associated with MS in the various human populations, thus supporting a primary effect of the products of these loci in MS. Overall these results are consistent with a multilocus model of the MHC encoded susceptibility to MS.

Differences in autonomic physiological responses between good and poor inductive reasoners

We investigated individual- and task-related differences in autonomic physiological responses induced by time limited figural and verbal inductive reasoning tasks. In a group of 52 participants, the percentage of correctly responded task items was evaluated together with nine different autonomic physiological response measures and respiration rate (RR). Weighted multidimensional scaling analyses of the physiological responses revealed three underlying dimensions, primarily characterized by RR, parasympathetic, and sympathetic activity. RR and sympathetic activity appeared to be relatively more important response dimensions for poor reasoners, whereas parasympathetic responsivity was relatively more important for good reasoners. These results suggest that poor reasoners showed higher levels of cognitive processing intensity than good reasoners. Furthermore, for the good reasoners, the dimension of sympathetic activity was relatively more important during the figural than during the verbal reasoning task, which was explained in terms of hemispheric lateralization in autonomic function.

High-resolution analysis of IL-6 minisatellite polymorphism in Sardinian multiple sclerosis: effect on course and onset of disease

A minisatellite polymorphism located in the 3' flanking region of the interleukin-6 (IL-6) gene was analysed in 192 Sardinian simplex families with multiple sclerosis (MS). By applying a high-resolution sizing approach, 9 alleles were identified. None of these were associated with in globo susceptibility to MS as shown by transmission disequilibrium testing. Analysis of clinically different groups showed that the A5 allele was associated with a benign (P = 0.007) but not with a malignant (P = 0.45) course of disease. In particular, the frequency of the A5/A5 genotype was significantly higher in patients with benign MS (P = 0.002). In addition, carriage of any of the larger alleles (A6-->A9) was associated with accelerated onset of disease (P = 0.025). Our results suggest that allelic variations in the IL-6 gene may predispose to alterations in the course and initial onset of MS.

[Lewis antigen and diabetes]

The Lewis negative (Le a--b--) red blood cell phenotype was observed three times more frequently in 170 diabetics (29%) irrespective of their clinical type and in 27 non-diabetics low insulin responders to glucose than in 100 controls (10%). This difference could not be accounted for by factors influencing the serological typing ("ABH secretion and ABO groups) nor by the geographic origin of the populations tested. The Lewis substances are primarly soluble antigens present in blood, saliva, others fluids and absorbed on red blood cells. In 50 diabetics saliva was also analysed. Blood cell and saliva results were concordant allowing to interpret the Lewis negative blood cell phenotype as reflecting the absence of Lewis antigen. The higher frequency of Lewis negative phenotype was not related to the severity or the duration of the diabetes and therefore was unlikely to depend on metabolic factors. The similarity between the results for juvenile and maturity onset diabetes seems to indicate that these two clinical types of diabetes are genetically related. Furthermore, the same results obtained in low insulin responders afford additional support for considering these subjects as potential diabetics. It probably indicates, in the diabetic population, an increased frequency of le/le genotype or of one or several genes inhibiting the expression of Le.

[14 cases of "anti-N" antibodies in hemodialysis patients in Marseille]

Some medical centers re-use dialysis units sterilized with formaldehyde. In a study of 239 cases, 14 "anti-N" antibodies were found only among the 59 patients of the medical centers which re-use dialysis units. The action of formol seems to be confirmed by the presence of "anti-N" in 2 patients who had undergone prosthesis several times, but not dialysis. For these prostheses, a bone cement, sterilized with formol, was used. These "anti-N" are very often associated with cold autoagglutinins, and appear regardless of the patient's MN group. The action of formaldehyde suggests the following hypotheses:--antigenic modification;--disturbances in the immune response mechanisms;--a combination of the two. In the first hypothesis: the action of formol discovered since a long time on red cells. In the second hypothesis: the existence of auto-agglutinins only among the 14 hemo-dialysis patients with anti-N antibodies.

[Irregular agglutinins, hemolysins, antilymphocyte antibodies, serum anticomplementarity, human and species antiglobulins and cryoglobulins in a series of 33 patients with rheumatoid arthritis]

An immunological investigation was carried out on 33 rheumatoid polyarthritis patients. The phenomena of antierythrocytes immunization were investigated by standard tests : irregular agglutinins, haemolysins, and auto-antibodies which all proved negative. The lymphocyte immunological phenomena were also studied. Cold (4 degrees C) lymphocytotoxins were shown in 8 patients, 5 of whom had anti-lymphocyte auto-antibodies. The proportions of "sheep rosettes" were significantly reduced. The sera did not show notable anti-complementary activity. Studies on the human antiglobulins and on species antiglobulins were not very conclusive. Cryoglobulins were never detected. No clear correlation was found between these different tests and those of standard rheumatism serology.