565 research outputs found
Citizen Science Time Domain Astronomy with Astro-COLIBRI
Astro-COLIBRI is an innovative tool designed for professional astronomers to
facilitate the study of transient astronomical events. Transient events - such
as supernovae, gamma-ray bursts and stellar mergers - are fleeting cataclysmic
phenomena that can offer profound insights into the most violent processes in
the universe. Revealing their secrets requires rapid and precise observations:
Astro-COLIBRI alerts its users of new transient discoveries from observatories
all over the world in real-time. The platform also provides observers the
details they need to make follow-up observations.
Some of the transient phenomena available through Astro-COLIBRI are
accessible by amateur astronomers and citizen scientists. A subset of the
features dedicated to this growing group of users are highlighted here. They
include the possibility of receiving only alerts on very bright events, the
possibility of defining custom observer locations, as well as the calculation
of optimized observation plans for searches for optical counterparts to
gravitational wave events.Comment: Proceedings Atelier Pro-AM Gemini, Journ\'ees SF2A 2023. arXiv admin
note: text overlap with arXiv:2308.0704
Decision process in large-scale crisis management
International audienceThis paper deals with the decision-aiding process in large-scale crisis such as natural disasters. It consists in four phases: decision context characterization, system modelling, aggregation and integration. The elements of the context, such as crisis level, risk situation, decision-maker problem issue are defined through the characterization phase. At the feared event occurrence, these elements will interact on a target system. Through the model on this system, the consequences to stakes could be assessed or estimated. The presented aggregation approaches will allow taking the right decisions. The architecture of a Decision Support System is presented in the integration phase
Drug hypersensitivity caused by alteration of the MHC-presented self-peptide repertoire
Idiosyncratic adverse drug reactions are unpredictable, dose independent and
potentially life threatening; this makes them a major factor contributing to
the cost and uncertainty of drug development. Clinical data suggest that many
such reactions involve immune mechanisms, and genetic association studies have
identified strong linkage between drug hypersensitivity reactions to several
drugs and specific HLA alleles. One of the strongest such genetic associations
found has been for the antiviral drug abacavir, which causes severe adverse
reactions exclusively in patients expressing the HLA molecular variant B*57:01.
Abacavir adverse reactions were recently shown to be driven by drug-specific
activation of cytokine-producing, cytotoxic CD8+ T cells that required
HLA-B*57:01 molecules for their function. However, the mechanism by which
abacavir induces this pathologic T cell response remains unclear. Here we show
that abacavir can bind within the F-pocket of the peptide-binding groove of
HLA-B*57:01 thereby altering its specificity. This supports a novel explanation
for HLA-linked idiosyncratic adverse drug reactions; namely that drugs can
alter the repertoire of self-peptides presented to T cells thus causing the
equivalent of an alloreactive T cell response. Indeed, we identified specific
self-peptides that are presented only in the presence of abacavir, and that
were recognized by T cells of hypersensitive patients. The assays we have
established can be applied to test additional compounds with suspected HLA
linked hypersensitivities in vitro. Where successful, these assays could speed
up the discovery and mechanistic understanding of HLA linked hypersensitivities
as well as guide the development of safer drugs
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The programming of sequences of saccades
Saccadic eye movements move the high-resolution fovea to point at regions of interest. Saccades can only be generated serially (i.e., one at a time). However, what remains unclear is the extent to which saccades are programmed in parallel (i.e., a series of such moments can be planned together) and how far ahead such planning occurs. In the current experiment, we investigate this issue with a saccade contingent preview paradigm. Participants were asked to execute saccadic eye movements in response to seven small circles presented on a screen. The extent to which participants were given prior information about target locations was varied on a trial-by-trial basis: participants were aware of the location of the next target only, the next three, five, or all seven targets. The addition of new targets to the display was made during the saccade to the next target in the sequence. The overall time taken to complete the sequence was decreased as more targets were available up to all seven targets. This was a result of a reduction in the number of saccades being executed and a reduction in their saccade latencies. Surprisingly, these results suggest that, when faced with a demand to saccade to a large number of target locations, saccade preparation about all target locations is carried out in paralle
Uncertainty information in climate data records from Earth observation
Climate data records (CDRs) derived from Earth observation (EO) should include rigorous uncertainty information, to support application of the data in policy, climate modelling and numerical weather prediction reanalysis. Uncertainty, error and quality are distinct concepts, and CDR products should follow international norms for presenting quantified uncertainty. Ideally, uncertainty should be quantified per datum in a CDR, and the uncertainty estimates should be able to discriminate more and less certain data with confidence. In this case, flags for data quality should not duplicate uncertainty information, but instead describe complementary information (such as the confidence held in the uncertainty estimate provided, or indicators of conditions violating retrieval assumptions). Errors have many sources and some are correlated across a wide range of time and space scales. Error effects that contribute negligibly to the total uncertainty in a single satellite measurement can be the dominant sources of uncertainty in a CDR on large space and long time scales that are highly relevant for some climate applications. For this reason, identifying and characterizing the relevant sources of uncertainty for CDRs is particularly challenging. Characterisation of uncertainty caused by a given error effect involves assessing the magnitude of the effect, the shape of the error distribution, and the propagation of the uncertainty to the geophysical variable in the CDR accounting for its error correlation properties. Uncertainty estimates can and should be validated as part of CDR validation, where possible. These principles are quite general, but the form of uncertainty information appropriate to different essential climate variables (ECVs) is highly variable, as confirmed by a quick review of the different approaches to uncertainty taken across different ECVs in the European Space Agency’s Climate Change Initiative. User requirements for uncertainty information can conflict with each other, and again a variety of solutions and compromises are possible. The concept of an ensemble CDR as a simple means of communicating rigorous uncertainty information to users is discussed. Our review concludes by providing eight recommendations for good practice in providing and communicating uncertainty in EO-based climate data records
Presence of papillomavirus sequences in condylomatous lesions of the mamillae and in invasive carcinoma of the breast
BACKGROUND: Viruses including Epstein–Barr virus (EBV), a human equivalent of murine mammary tumour virus (MMTV) and human papillomavirus (HPV) have been implicated in the aetiology of human breast cancer. We report the presence of HPV DNA sequences in areolar tissue and tumour tissue samples from female patients with breast carcinoma. The presence of virus in the areolar–nipple complex suggests to us a potential pathogenic mechanism. METHODS: Polymerase chain reaction (PCR) was undertaken to amplify HPV types in areolar and tumour tissue from breast cancer cases. In situ hybridisation supported the PCR findings and localised the virus in nipple, areolar and tumour tissue. RESULTS: Papillomavirus DNA was present in 25 of 29 samples of breast carcinoma and in 20 of 29 samples from the corresponding mamilla. The most prevalent type in both carcinomas and nipples was HPV 11, followed by HPV 6. Other types detected were HPV 16, 23, 27 and 57 (nipples and carcinomas), HPV 20, 21, 32, 37, 38, 66 and GA3-1 (nipples only) and HPV 3, 15, 24, 87 and DL473 (carcinomas only). Multiple types were demonstrated in seven carcinomas and ten nipple samples. CONCLUSIONS: The data demonstrate the occurrence of HPV in nipple and areolar tissues in patients with breast carcinoma. The authors postulate a retrograde ductular pattern of viral spread that may have pathogenic significance
Immunological Detection of Potential Signal-Transduction Proteins Expressed during Wheat Somatic Tissue Culture
H.E.S.S. Follow-up Observations of GRB 221009A
GRB 221009A is the brightest gamma-ray burst (GRB) ever detected. To probe the very-high-energy (VHE; >100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hr after the triggering event, when the brightness of the moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from the third, fourth, and ninth nights after the initial GRB detection, after applying atmospheric corrections. The combined observations yield an integral energy flux upper limit of FUL = 9.7 ´ 10- erg cm- s- 95% 12 2 1 above Ethr = 650 GeV. The constraints derived from the H.E.S.S. observations complement the available multiwavelength data. The radio to X-ray data are consistent with synchrotron emission from a single electron population, with the peak in the spectral energy distribution occurring above the X-ray band. Compared to the VHE-bright GRB 190829A, the upper limits for GRB 221009A imply a smaller gamma-ray to X-ray flux ratio in the afterglow. Even in the absence of a detection, the H.E.S.S. upper limits thus contribute to the multiwavelength picture of GRB 221009A, effectively ruling out an IC-dominated scenario.F. Aharonian ... S. Einecke ... G. Rowell ... et al. (H.E.S.S. Collaboration
The Vanishing of the Primary Emission Region in PKS 1510–089
Published 2023 August 1In 2021 July, PKS 1510−089 exhibited a significant flux drop in the high-energy γ-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementioned bands, the very-high-energy γ-ray and X-ray fluxes did not exhibit a significant flux drop from year to year. This suggests that the steady-state very-high-energy γ-ray and X-ray fluxes originate from a different emission region than the vanished parts of the high-energy γ-ray and optical jet fluxes. The latter component has disappeared through either a swing of the jet away from the line of sight or a significant drop in the photon production efficiency of the jet close to the black hole. Either change could become visible in high-resolution radio images.F. Aharonian ... S. Einecke ... G. Rowell ... et al. (H.E.S.S. Collaboration
Photosynthetic growth despite a broken Q-cycle
Central in respiration or photosynthesis, the cytochrome bc1 and b6f complexes are regarded as functionally similar quinol oxidoreductases. They both catalyse a redox loop, the Q-cycle, which couples electron and proton transfer. This loop involves a bifurcated electron transfer step considered as being mechanistically mandatory, making the Q-cycle indispensable for growth. Attempts to falsify this paradigm in the case of cytochrome bc1 have failed. The rapid proteolytic degradation of b6f complexes bearing mutations aimed at hindering the Q-cycle has precluded so far the experimental assessment of this model in the photosynthetic chain. Here we combine mutations in Chlamydomonas that inactivate the redox loop but preserve high accumulation levels of b6f complexes. The oxidoreductase activity of these crippled complexes is sufficient to sustain photosynthetic growth, which demonstrates that the Q-cycle is dispensable for oxygenic photosynthesis
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