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.

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.

Cost-effectiveness analysis of resorbable biosynthetic mesh in contaminated ventral hernia repair.

BACKGROUND: The aim of this study was to compare, in terms of cost and serious complications, the use of biosynthetic resorbable parietal mesh with biologic mesh in patients undergoing contaminated ventral hernia repair (modified Ventral Hernia Working Group grade 3). Poly-4-hydroxy-butyrate (P4HB) biosynthetic mesh has rarely been the subject of comparative studies in the context of contamination. Data are required to confirm the effects of a transition from biological mesh to biosynthetic resorbable mesh. PATIENTS AND METHODS: A cost-effectiveness analysis was conducted. It was based on a decision analysis model built with clinical and economic data issued from a before-after study that included 94 patients hospitalized for ventral hernia repair at the University Hospital of Strasbourg (France) from June 2011 to February 2018. The effectiveness endpoint was the number of patients presenting with a serious specific complication or a general complication at 6 months. Data for surgical hospitalization stays, home hospitalizations and ambulatory care costs were included. RESULTS: We found fewer serious complications with biosynthetic mesh: 21% versus 33% with biologic mesh. A cost savings of US $5146 was determined. Deterministic sensitivity analyses and a probabilistic analysis confirmed our findings and the robustness of the model. CONCLUSION: P4HB biosynthetic resorbable mesh appeared to be the most effective and the least costly option. Additional data will be needed to confirm the superiority of biosynthetic mesh in terms of the recurrence risk reduction over a longer period.

Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow.

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

A very-high-energy component deep in the γ-ray burst afterglow.

Gamma-ray bursts (GRBs) are brief flashes of γ-rays and are considered to be the most energetic explosive phenomena in the Universe1. The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow-produced by the interaction between the ejected matter and the circumburst medium-slows down, and a gradual decrease in brightness is observed2. GRBs typically emit most of their energy via γ-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments3. However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive4. Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow-ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and γ-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.

Table-top high-energy 7 µm OPCPA and 260 mJ Ho:YLF pump laser.

We present a state-of-the-art compact high-energy mid-infrared (mid-IR) laser system for TW-level eight-cycle pulses at 7 µm. This system consists of an Er:Tm:Ho:fiber MOPA which serves as the seeder for a ZGP-based optical parametric chirped pulse amplification (OPCPA) chain, in addition to a Ho:YLF amplifier which is Tm:fiber pumped. Featuring all-optical synchronization, the system delivers 260 mJ pump energy at 2052 nm and 16 ps duration at 100 Hz with a stability of 0.8% rms over 20 min. We show that chirp inversion in the OPCPA chain leads to excellent energy extraction and aids in compression of the 7 µm pulses to eight optical cycles (188 fs) in bulk BaF2 with 93.5% efficiency. Using 21.7 mJ of the available pump energy, we generate 0.75 mJ energy pulses at 7 µm due to increased efficiency with a chirp inversion scheme. The pulse quality of the system's output is shown by generating high harmonics in ZnSe which span up to harmonic order 13 with excellent contrast. The combination of the passive carrier-envelope phase stable mid-IR seed pulses and the high-energy 2052 nm picosecond pulses makes this compact system a key enabling tool for the next generation of studies on extreme photonics, strong field physics, and table-top coherent X-ray science.

Search for γ-Ray Line Signals from Dark Matter Annihilations in the Inner Galactic Halo from 10 Years of Observations with H.E.S.S.

Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy γ rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of the signal versus background. The analysis makes use of Galactic center observations accumulated over ten years (2004-2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant γ-ray excess above the background is found. We derive upper limits on the annihilation cross section ⟨σv⟩ for monoenergetic DM lines at the level of 4×10^{-28} cm^{3} s^{-1} at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of 6. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV-70 TeV. Ground-based γ-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two γ-ray photons at the level expected from the thermal relic density for TeV DM particles.

Preparation of monopodal and bipodal aluminum surface species by selective protonolysis of highly reactive [AlH3(NMe2Et)] on silica.

The synthesis and characterization of silica-grafted monopodal and bipodal aluminum hydrides has been achieved starting from 200 °C- and 700 °C-annealed silica and [AlH3(NMe2Et)]. The mechanism by which aluminum trishydride reacts with isolated and vicinal silanols, assisted by the amine, has been investigated computationally at the ωB97XD-DFT level.

Highly scalable femtosecond coherent beam combining demonstrated with 19 fibers.

Coherent beam combining in the femtosecond regime of a record number of 19 fibers is demonstrated. The interferometric phase measurement technique, particularly well suited to phase-lock a very large number of fibers, is successfully demonstrated in the femtosecond regime. A servo loop is implemented to control piezoelectric fiber stretchers for both phase and delay variation compensation. The residual phase errors are below λ/60 rms. Nearly 50% of the total energy is contained in the far-field central lobe. After compression, we obtain a combined pulse width of 300 fs identical to the master oscillator pulse width.

H.E.S.S. Limits on Linelike Dark Matter Signatures in the 100 GeV to 2 TeV Energy Range Close to the Galactic Center.

A search for dark matter linelike signals iss performed in the vicinity of the Galactic Center by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis iss developed to improve the sensitivity to linelike signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% C.L. the presence of a 130 GeV line (at l=-1.5°, b=0° and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S. RESULTS: No significant excess associated with dark matter annihilations was found in the energy range of 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given.

Search for Dark Matter Annihilations towards the Inner Galactic Halo from 10 Years of Observations with H.E.S.S.

The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using γ-ray observations towards the inner 300 pc of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic Center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant γ-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section ⟨σv⟩. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach ⟨σv⟩ values of 6×10^{-26} cm^{3} s^{-1} in the W^{+}W^{-} channel for a DM particle mass of 1.5 TeV, and 2×10^{-26} cm^{3} s^{-1} in the τ^{+}τ^{-} channel for a 1 TeV mass. For the first time, ground-based γ-ray observations have reached sufficient sensitivity to probe ⟨σv⟩ values expected from the thermal relic density for TeV DM particles.

Constraints on an annihilation signal from a core of constant dark matter density around the milky way center with H.E.S.S.

An annihilation signal of dark matter is searched for from the central region of the Milky Way. Data acquired in dedicated on-off observations of the Galactic center region with H.E.S.S. are analyzed for this purpose. No significant signal is found in a total of ∼9 h of on-off observations. Upper limits on the velocity averaged cross section, ⟨σv⟩, for the annihilation of dark matter particles with masses in the range of ∼300 GeV to ∼10 TeV are derived. In contrast to previous constraints derived from observations of the Galactic center region, the constraints that are derived here apply also under the assumption of a central core of constant dark matter density around the center of the Galaxy. Values of ⟨σv⟩ that are larger than 3×10^{-24} cm^{3}/s are excluded for dark matter particles with masses between ∼1 and ∼4 TeV at 95% C.L. if the radius of the central dark matter density core does not exceed 500 pc. This is the strongest constraint that is derived on ⟨σv⟩ for annihilating TeV mass dark matter without the assumption of a centrally cusped dark matter density distribution in the search region.

Search for photon-linelike signatures from dark matter annihilations with H.E.S.S.

Gamma-ray line signatures can be expected in the very-high-energy (E(γ)>100 GeV) domain due to self-annihilation or decay of dark matter (DM) particles in space. Such a signal would be readily distinguishable from astrophysical γ-ray sources that in most cases produce continuous spectra that span over several orders of magnitude in energy. Using data collected with the H.E.S.S. γ-ray instrument, upper limits on linelike emission are obtained in the energy range between ∼ 500 GeV and ∼ 25 TeV for the central part of the Milky Way halo and for extragalactic observations, complementing recent limits obtained with the Fermi-LAT instrument at lower energies. No statistically significant signal could be found. For monochromatic γ-ray line emission, flux limits of (2 × 10(-7) -2 × 10(-5)) m(-2) s(-1) sr(-1) and (1 × 10(-8) -2 × 10(-6)) m(-2) s(-1)sr(-1) are obtained for the central part of the Milky Way halo and extragalactic observations, respectively. For a DM particle mass of 1 TeV, limits on the velocity-averaged DM annihilation cross section ⟨σv⟩(χχ → γγ) reach ∼ 10(-27) cm(3)s(-1), based on the Einasto parametrization of the Galactic DM halo density profile.

[Sugammadex and renal failure: a case report]. / Sugammadex et insuffisance rénale: à propos d'un cas.

We report a case of delayed rocuronium-induced deep block antagonization with sugammadex, thus requiring a total of three injections and a cumulative dose of 12 mg/kg over a 30 min period. The patient was an emergency case with full stomach that had required a rapid sequence induction. Because of hyperkaliemia due to an acute renal failure, rocuronium was preferred to succinylcholine. Use of sugammadex in the acute renal failure context is discussed.

Search for a dark matter annihilation signal from the galactic center halo with H.E.S.S.

A search for a very-high-energy (VHE; ≥100 GeV) γ-ray signal from self-annihilating particle dark matter (DM) is performed towards a region of projected distance r∼45-150 pc from the Galactic center. The background-subtracted γ-ray spectrum measured with the High Energy Stereoscopic System (H.E.S.S.) γ-ray instrument in the energy range between 300 GeV and 30 TeV shows no hint of a residual γ-ray flux. Assuming conventional Navarro-Frenk-White and Einasto density profiles, limits are derived on the velocity-weighted annihilation cross section (σv) as a function of the DM particle mass. These are among the best reported so far for this energy range and in particular differ only little between the chosen density profile parametrizations. In particular, for the DM particle mass of ∼1 TeV, values for (σv) above 3×10(-25) cm(3) s(-1) are excluded for the Einasto density profile.

[Triple nerve block for ambulatory knee arthroscopy]. / Tribloc (fémoral, sciatique, obturateur) pour la chirurgie ambulatoire arthroscopique de genou: étude prospective de faisabilité et d'efficacité.

BACKGROUND: The purpose of this study was to evaluate intra- and postoperative conditions of the triple nerve block technique (femoral, obturator, sciatic block) for outpatient knee arthroscopic procedures. METHODS: After written informed consent, ASA I-III patients received a combined triple nerve block with 30-40 ml lidocaine or mepivacaine (1,5%). Blocks were performed using a nerve stimulation technique. Onset time, block failure, supplemental general anesthesia (GA) or analgesia and pain score were recorded intraoperatively. After surgery, side effects (at days 0, 1, 3, 7 and after 4 weeks), patient and surgeon satisfactions were noted. RESULTS: Three hundred and twelve patients were screened and 115 triple blocks were performed (157 chose GA, 19 spinal anaesthesia, 21 exclusion for regional anaesthesia). Failed blocks occurred for 12 (10%) patients. These 12 patients received GA before surgery incision. Time to complete block was 40 (10-60) min. Supplemental GA was required for 12 patients (12%) due to surgical (n=7, 7%) or tourniquet (n=5, 5%) pain. Intraoperative surgeon satisfaction was 90 (60-100). After surgery, time to discharge the postoperative care unit was 15 (5-60) min. Pain score at rest (Visual Analog Scale) until six hours was less than 30 /100, without any additional morphine. Two patients (< 2%) failed for ambulatory discharge criteria (no relation with triple block). At day 0, 3, 5% patients suffered PONV (8% at D1), paresthesia was noted in 1.7% at D0 (0,8% D3). No other secondary effects were observed after seven days and 91% patients "would like same anaesthesia" for next surgery. CONCLUSION: We conclude that triple nerve block provided reliable intraoperative patient and surgical conditions for outpatient knee arthroscopy. Failed block (10%) was the major reason of supplemental anaesthesia. To increase surgical turn over under triple nerve block, a preoperative room may be required (block onset time).

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.

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.

[Blood requirements and transfusion practice evolution in surgery]. / Evolution des besoins transfusionnels en chirurgie.

During the years 1990, the focus was on transfusion hazards and blood savings strategies. This resulted in a decrease in labile blood products consumption. For a few years, there is a reverse tendency, with a reincrease in blood products consumption. In the same time, the limit of saving strategies has been attained, by identifying the risk of lack of transfusion (or too low transfusion threshold). A so-called multimodal blood savings strategy must be set. Vigilance is mandatory concerning the blood savings strategies that are detailed by scientific societies consensus conferences. Those strategies include a good anticipation of blood requirement, improvement of surgical techniques, pre- and intra-operative autologous transfusion, blood clotting pharmacological improvements, and anesthesia techniques. Transfusion today is relatively safe. Blood requirements must be precisely assessed to avoid going from Charybdis to Scylla i.e. from over- to under-transfusion.