Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433.

SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.

Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey.

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100 GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26} cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26} cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi.

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE; [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to 1 month after its 2021 outburst, observed using the High Energy Stereoscopic System (H.E.S.S.). The temporal profile of VHE emission is similar to that of lower-energy giga-electron volt emission, indicating a common origin, with a 2-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic rays to very high energies.

A large oxygen-dominated core from the seismic cartography of a pulsating white dwarf.

White-dwarf stars are the end product of stellar evolution for most stars in the Universe. Their interiors bear the imprint of fundamental mechanisms that occur during stellar evolution. Moreover, they are important chronometers for dating galactic stellar populations, and their mergers with other white dwarfs now appear to be responsible for producing the type Ia supernovae that are used as standard cosmological candles. However, the internal structure of white-dwarf stars-in particular their oxygen content and the stratification of their cores-is still poorly known, because of remaining uncertainties in the physics involved in stellar modelling codes. Here we report a measurement of the radial chemical stratification (of oxygen, carbon and helium) in the hydrogen-deficient white-dwarf star KIC08626021 (J192904.6+444708), independently of stellar-evolution calculations. We use archival data coupled with asteroseismic sounding techniques to determine the internal constitution of this star. We find that the oxygen content and extent of its core exceed the predictions of existing models of stellar evolution. The central homogeneous core has a mass of 0.45 solar masses, and is composed of about 86 per cent oxygen by mass. These values are respectively 40 per cent and 15 per cent greater than those expected from typical white-dwarf models. These findings challenge present theories of stellar evolution and their constitutive physics, and open up an avenue for calibrating white-dwarf cosmochronology.

Leptospirosis in domestic animals in France: serological results from 1988 to 2007.

Leptospirosis is a common infection in domestic animals. The microscopic agglutination test (MAT) is used for serological diagnosis. From 1988 to 2007, the Leptospira Medical and Molecular Bacteriology Laboratory at the Nantes National College of Veterinary Medicine, Food Science and Engineering used the MAT to test serum samples from more than 40,000 cattle, 40,000 pigs, 20,000 horses and 9,500 dogs. Five Leptospira serogroups were prominent, with specific variations within the four animal species: Icterohaemorrhagiae, Australis, Sejroë, Grippotyphosa and Autumnalis. The prevalence and incidence of each serogroup varied for each species over the 20-year period: some serogroups were emergent during some years but disappeared later. This study reports the complex epidemiological features of leptospirosis.

La leptospirose est une infection courante affectant les animaux domestiques. Le diagnostic sérologique est réalisé au moyen du test d'agglutination microscopique (MAT). De 1988 à 2007, le Laboratoire de l'Unité de recherche de bactériologie médicale et moléculaire des leptospires (École nationale vétérinaire, agroalimentaire et de l'alimentation de Nantes) a utilisé cette épreuve pour tester des échantillons de sérum prélevés sur plus de 40 000 bovins, 40 000 porcs, 20 000 chevaux et 9 500 chiens. Cinq sérogroupes de Leptospira étaient majoritairement présents, à savoir Icterohaemorrhagiae, Australis, Sejroë, Grippotyphosa et Autumnalis, avec des variations en fonction de l'espèce. La prévalence et l'incidence des différents sérogroupes dans chacune des quatre espèces ont présenté des fluctuations au cours des vingt années de l'étude, certains sérogroupes ayant émergé pendant quelques années, puis régressé. Cette étude fait état de la complexité des caractéristiques épidémiologiques de la leptospirose.

La leptospirosis es una infección frecuente en los animales domésticos, para cuyo diagnóstico serológico se utiliza la prueba de aglutinación microscópica. Entre 1988 y 2007, el Laboratorio de Bacteriología Médica y Molecular de las Leptospiras de la Facultad Nacional Veterinaria, Agroalimentaria y de Alimentación Nantes-Atlántico aplicó dicha prueba al análisis de muestras séricas de más de 40 000 vacunos, 40 000 cerdos, 20 000 caballos y 9 500 perros. Se observó que predominaban cinco serogrupos de Leptospira, con variaciones específicas dentro de las cuatro especies animales: Icterohaemorrhagiae, Australis, Sejroë, Grippotyphosa y Autumnalis. En cada especie, la prevalencia y la incidencia de uno u otro serogrupo fueron variando a lo largo de esos veinte años: algunos serogrupos aparecían durante unos años para desaparecer después. En este estudio, la autora da cuenta de las complejas características epidemiológicas de la leptospirosis.

Modifications of the endosomal compartment in peripheral blood mononuclear cells and fibroblasts from Alzheimer's disease patients.

Identification of blood-based biomarkers of Alzheimer's disease (AD) remains a challenge. Neuropathological studies have identified enlarged endosomes in post-mortem brains as the earliest cellular change associated to AD. Here the presence of enlarged endosomes was investigated in peripheral blood mononuclear cells from 48 biologically defined AD patients (25 with mild cognitive impairment and 23 with dementia (AD-D)), and 23 age-matched healthy controls using immunocytochemistry and confocal microscopy. The volume and number of endosomes were not significantly different between AD and controls. However, the percentage of cells containing enlarged endosomes was significantly higher in the AD-D group as compared with controls. Furthermore, endosomal volumes significantly correlated to [C(11)]PiB cortical index measured by positron emission tomography in the AD group, independently of the APOE genotype, but not to the levels of amyloid-beta, tau and phosphorylated tau measured in the cerebrospinal fluid. Importantly, we confirmed the presence of enlarged endosomes in fibroblasts from six unrelated AD-D patients as compared with five cognitively normal controls. This study is the first, to our knowledge, to report morphological alterations of the endosomal compartment in peripheral cells from AD patients correlated to amyloid load that will now be evaluated as a possible biomarker.

Starch-Based Layer by Layer Assembly: Efficient and Sustainable Approach to Cotton Fire Protection.

Starch has been employed via layer by layer assembly for building an efficient and sustainable biobased coatings capable of protecting cotton from fire. In order to obtain a better understanding of the coating to substrate relationship, the coating efficiency has been tested on cotton fabrics having different densities (i.e., 100, 200, and 400 g/m(2)). The adopted deposition conditions allow for the buildup of a homogeneous coating even at a low number of deposition steps. The physical and chemical mechanisms are described and related to the achieved results. The coating can greatly enhance the char forming ability of cellulose, nearly doubling the amount of thermally stable organic residue produced by cotton at high temperatures, as assessed by thermogravimetric analyses. After only 2 bilayers deposited, this biobased system is capable of self-extinguishing a flame during flammability tests with less than 5% in weight deposited on cotton. This high efficiency is kept even when the coating is deposited on cotton with the highest density. By cone calorimetry, all treated cottons showed significant reductions (up to 40%) of the total heat released during combustion, thus demonstrating the high efficiency achieved.

Diagnosis algorithm for leptospirosis in dogs: disease and vaccination effects on the serological results.

Leptospirosis is a common disease in dogs, despite their current vaccination. Vet surgeons may use a serological test to verify their clinical observations. The gold standard is the Microscopic Agglutination Test (MAT). After infection, the dog produces agglutinating antibodies against the lipopolyosidic antigens shared by the infectious strain but also, after vaccination, against the lipopolyosidic antigens shared by the serovars used in the bacterins (Leptospira species serovars Icterohaemorrhagiae and Canicola in most countries). MATs were performed in a group of 102 healthy field dogs and a group of 6 Canicola-challenged dogs. A diagnosis algorithm was constructed based on age, previous vaccinations, kinetics of the agglutinating antibodies after infection or vaccination and the delay after onset of the disease. This algorithm was applied to 169 well-documented sera (clinical and vaccine data) from 272 sick dogs with suspected leptospirosis. Totally, 102 dogs were vaccinated according to the usual vaccination scheme and 30 were not vaccinated. Leptospirosis was confirmed by MAT in 37/102 (36.2 per cent) vaccinated dogs and remained probable in 14 others (13.7 per cent), thus indicating the permanent exposure of dogs and the weakness of the protection offered by the current vaccines to pathogenic Leptospira.

A compact system of small planets around a former red-giant star.

Planets that orbit their parent star at less than about one astronomical unit (1 AU is the Earth-Sun distance) are expected to be engulfed when the star becomes a red giant. Previous observations have revealed the existence of post-red-giant host stars with giant planets orbiting as close as 0.116 AU or with brown dwarf companions in tight orbits, showing that these bodies can survive engulfment. What has remained unclear is whether planets can be dragged deeper into the red-giant envelope without being disrupted and whether the evolution of the parent star itself could be affected. Here we report the presence of two nearly Earth-sized bodies orbiting the post-red-giant, hot B subdwarf star KIC 05807616 at distances of 0.0060 and 0.0076 AU, with orbital periods of 5.7625 and 8.2293 hours, respectively. These bodies probably survived deep immersion in the former red-giant envelope. They may be the dense cores of evaporated giant planets that were transported closer to the star during the engulfment and triggered the mass loss necessary for the formation of the hot B subdwarf, which might also explain how some stars of this type did not form in binary systems.

Synthetic peptide issued from Hap1/LipL32 for new early serodiagnosis of human leptospirosis.

Leptospirosis is a worldwide zoonosis. Today, serological diagnosis is generally assessed by MAT. We performed ELISA with a synthetic peptide derived from Hap1/lipL32 which is a protein expressed only by pathogenic Leptospira. Repeatability and thresholds were defined with 85 controls sera and 119 hospitalized leptospirosis. The PP-ELISA repeatability and IgM/IgG cut-off values were based on control sera. For these cut-off values, we observed the IgM-PP-ELISA specificity of 89%, whereas it was 100% for the IgG. Then, we compared PP-ELISA and standard MAT results for leptospirosis patients. The concordance rate for IgM-PP-ELISA and MAT was low (43%), whereas it was 85% for IgG-PP-ELISA and MAT. During the first 5 days after hospitalization, PP-ELISA gave positive results in 13 out of 16 patients (81%) whereas 8 out of 14 patients (57%) were positive to MAT. ELISA using Hap1/lipL 32-derived synthetic peptide PP is an earlier serological diagnosis of human leptospirosis than MAT.

Seismic evidence for the loss of stellar angular momentum before the white-dwarf stage.

White-dwarf stars represent the final products of the evolution of some 95% of all stars. If stars were to keep their angular momentum throughout their evolution, their white-dwarf descendants, owing to their compact nature, should all rotate relatively rapidly, with typical periods of the order of a few seconds. Observations of their photospheres show, in contrast, that they rotate much more slowly, with periods ranging from hours to tens of years. It is not known, however, whether a white dwarf could 'hide' some of its original angular momentum below the superficial layers, perhaps spinning much more rapidly inside than at its surface. Here we report a determination of the internal rotation profile of a white dwarf using a method based on asteroseismology. We show that the pulsating white dwarf PG 1159-035 rotates as a solid body (encompassing more than 97.5% of its mass) with the relatively long period of 33.61 +/- 0.59 h. This implies that it has lost essentially all of its angular momentum, thus favouring theories which suggest important angular momentum transfer and loss in evolutionary phases before the white-dwarf stage.

Detection of gamma rays from a starburst galaxy.

Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of approximately 10(15) electron volts. We report the detection of gamma rays--tracers of such cosmic rays--from the starburst galaxy NGC 253 using the High Energy Stereoscopic System (H.E.S.S.) array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 billion electron volts is F = (5.5 +/- 1.0(stat) +/- 2.8(sys)) x 10(-13) cm(-2) s(-1), implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is five times as large as that in our Galaxy.

Leptospira exposure in the human environment in France: A survey in feral rodents and in fresh water.

This paper confirms the important role of rodents to be maintenance hosts of leptospires. Their role is related to renal carriage and shedding of leptospires into urine, thus contaminating fresh water. Serological and carriage of feral rodents trapped in France were determined by MAT and hap1PCR specific for pathogenic leptospires. In same areas, fresh water samples were analyzed by hap1PCR. The overall seroprevalence was 44% in 649 rodents and was similar regardless of the species. Seroprevalence for leptospirosis is about 20-53% according to species. hap1PCR (516 kidneys) showed that renal carriage was higher in brown rats (34.7%) and muskrats (15.8%) than in coypus (3.3%). hap1PCR demonstrates a significative difference (P-value > 10(-12)) for the renal carriage between the different species: muskrats and rats are more efficient maintenance hosts than coypu but all infect water. Moreover 5/38 water samples associated with human cases were hap1PCR positive and 1/113 in controlled waters.

Limits on an energy dependence of the speed of light from a flare of the active galaxy PKS 2155-304.

In the past few decades, several models have predicted an energy dependence of the speed of light in the context of quantum gravity. For cosmological sources such as active galaxies, this minuscule effect can add up to measurable photon-energy dependent time lags. In this Letter a search for such time lags during the High Energy Stereoscopic System observations of the exceptional very high energy flare of the active galaxy PKS 2155-304 on 28 July 2006 is presented. Since no significant time lag is found, lower limits on the energy scale of speed of light modifications are derived.

[Seroprevalence of Lyme Borreliosis and tick-borne encephalitis in workers at risk, in eastern France]. / Séroprévalence de la borréliose de Lyme et de l'encéphalite à tiques chez des professionnels exposés dans le Grand est de la France.

OBJECTIVE: The aim of this article was to assess the seroprevalence of Lyme Borreliosis and tick-borne encephalitis (TBE) among occupationally exposed forest workers. METHODS: Workers exposed to tick bites in Eastern France were interviewed by occupational health physicians of the mutualité sociale agricole (MSA) on their sociodemographic features, their occupational activity, their last tick bite, their clinical history, and their means of prevention. Blood sampling was carried out for antibody detection. RESULTS: Among the 2975 subjects included in the study, the observed seroprevalence was 14.1% for Lyme borreliosis and 3.4% for TBE. Age, occupational activity, and place of residence significantly influenced the serological status of Lyme borreliosis. The seroprevalence was significantly higher among woodcutters (17.5%) than among other occupational categories (p<.001). Seroprevalence in Alsace (26.9%) and Lorraine (16.5%) were significantly higher than in other regions (p<0.001 and p<0.01, respectively). The seroprevalence of TBE was significantly higher in Alsace (5.5%; p<0.001). The rates of seroprevalence for both infections varied according to forest areas. The multifactorial analysis of prevention practices revealed three types of behaviors as far as protection was concerned: "rigorous", "partial", or "insufficient". CONCLUSION: These results do not change the present French indications for use of TBE vaccine. They highlight the importance of information on these diseases and the need for further studies on microbial ecology and risk-factors identification.

Energy spectrum of cosmic-ray electrons at TeV energies.

The very large collection area of ground-based gamma-ray telescopes gives them a substantial advantage over balloon or satellite based instruments in the detection of very-high-energy (>600 GeV) cosmic-ray electrons. Here we present the electron spectrum derived from data taken with the High Energy Stereoscopic System (H.E.S.S.) of imaging atmospheric Cherenkov telescopes. In this measurement, the first of this type, we are able to extend the measurement of the electron spectrum beyond the range accessible to direct measurements. We find evidence for a substantial steepening in the energy spectrum above 600 GeV compared to lower energies.

White dwarf stars with carbon atmospheres.

White dwarfs represent the endpoint of stellar evolution for stars with initial masses between approximately 0.07 and 8-10, where is the mass of the Sun (more massive stars end their life as either black holes or neutron stars). The theory of stellar evolution predicts that the majority of white dwarfs have a core made of carbon and oxygen, which itself is surrounded by a helium layer and, for approximately 80 per cent of known white dwarfs, by an additional hydrogen layer. All white dwarfs therefore have been traditionally found to belong to one of two categories: those with a hydrogen-rich atmosphere (the DA spectral type) and those with a helium-rich atmosphere (the non-DAs). Here we report the discovery of several white dwarfs with atmospheres primarily composed of carbon, with little or no trace of hydrogen or helium. Our analysis shows that the atmospheric parameters found for these stars do not fit satisfactorily in any of the currently known theories of post-asymptotic giant branch evolution, although these objects might be the cooler counterpart of the unique and extensively studied PG 1159 star H1504+65 (refs 4-7). These stars, together with H1504+65, might accordingly form a new evolutionary sequence that follows the asymptotic giant branch.

HESS observations of the galactic center region and their possible dark matter interpretation.

The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin.

Fast variability of tera-electron volt gamma rays from the radio galaxy M87.

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.

A low level of extragalactic background light as revealed by gamma-rays from blazars.

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the 'first stars', which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the gamma-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of gamma-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources-in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to gamma-rays than previously thought.