ABSTRACT We report on radio and X-ray observations of the only known repeating Fast Radio Burst (FRB) source, FRB 121102. We have detected six additional radio bursts from this source: five with the ...Green Bank Telescope at 2 GHz, and one at 1.4 GHz with the Arecibo Observatory, for a total of 17 bursts from this source. All have dispersion measures consistent with a single value (∼559 pc cm−3) that is three times the predicted maximum Galactic contribution. The 2 GHz bursts have highly variable spectra like those at 1.4 GHz, indicating that the frequency structure seen across the individual 1.4 and 2 GHz bandpasses is part of a wideband process. X-ray observations of the FRB 121102 field with the Swift and Chandra observatories show at least one possible counterpart; however, the probability of chance superposition is high. A radio imaging observation of the field with the Jansky Very Large Array at 1.6 GHz yields a 5 upper limit of 0.3 mJy on any point-source continuum emission. This upper limit, combined with archival Wide-field Infrared Survey Explorer 22 m and IPHAS H surveys, rules out the presence of an intervening Galactic H ii region. We update our estimate of the FRB detection rate in the PALFA survey to be FRBs sky−1 day−1 (95% confidence) for peak flux density at 1.4 GHz above 300 mJy. We find that the intrinsic widths of the 12 FRB 121102 bursts from Arecibo are, on average, significantly longer than the intrinsic widths of the 13 single-component FRBs detected with the Parkes telescope.
A repeating fast radio burst Spitler, L G; Scholz, P; Hessels, J W T ...
Nature (London),
03/2016, Volume:
531, Issue:
7593
Journal Article
Peer reviewed
Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find ...additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.
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Background
The level of neuromuscular blockade (NMB) that provides optimal surgical conditions during abdominal surgery has not been well established. The aim of this systematic review was to ...evaluate current evidence on the use of neuromuscular blocking agents in order to optimise surgical conditions during laparoscopic procedures and open abdominal surgery.
Methods
A wide search was performed in PubMed, Cochrane library and Embase with systematic approach including PRISMA recommendations. Individual risk of bias was assessed and systematic data extraction were performed.
Results
Fifteen studies with data from 998 patients were included. There is good evidence that the use of deep NMB compared with moderate NMB is associated with optimised surgical conditions during laparoscopic cholecystectomy, hysterectomy and nephrectomy/prostatectomy. In laparoscopic cholecystectomy during low pressure pneumoperitoneum, deep NMB marginally improves the surgical conditions. However, to ensure acceptable surgical conditions, it may be necessary to increase the intra‐abdominal pressure in up to half of the patients regardless of level of NMB. There is good evidence that moderate NMB improves surgical conditions in some cases during open radical retropubic prostatectomy. However, good and excellent surgical conditions may be achievable even without NMB. There is good evidence to recommend deep NMB in laparoscopic cholecystectomy, nephrectomy and prostatectomy to improve surgical conditions. There is insufficient evidence to recommend an ideal level of NMB creating optimal surgical condition during laparotomy.
Conclusion
Use of deep NMB in certain laparoscopic procedures may improve surgical conditions. In open abdominal surgery, use of NMB may optimise surgical conditions under certain circumstances.
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ABSTRACT We report the discovery of two long-term intermittent radio pulsars in the ongoing Pulsar Arecibo L-Band Feed Array survey. Following discovery with the Arecibo Telescope, extended ...observations of these pulsars over several years at Jodrell Bank Observatory have revealed the details of their rotation and radiation properties. PSRs J1910+0517 and J1929+1357 show long-term extreme bimodal intermittency, switching between active (ON) and inactive (OFF) emission states and indicating the presence of a large, hitherto unrecognized underlying population of such objects. For PSR J1929+1357, the initial duty cycle was fON = 0.008, but two years later, this changed quite abruptly to fON = 0.16. This is the first time that a significant evolution in the activity of an intermittent pulsar has been seen, and we show that the spin-down rate of the pulsar is proportional to the activity. The spin-down rate of PSR J1929+1357 is increased by a factor of 1.8 when it is in active mode, similar to the increase seen in the other three known long-term intermittent pulsars. These discoveries increase the number of known pulsars displaying long-term intermittency to five. These five objects display a remarkably narrow range of spin-down power ( ) and accelerating potential above their polar caps. If confirmed by further discoveries, this trend might be important for understanding the physical mechanisms that cause intermittency.
ABSTRACT We report here the Einstein@Home discovery of PSR J1913+1102, a 27.3 ms pulsar found in data from the ongoing Arecibo PALFA pulsar survey. The pulsar is in a 4.95 hr double neutron star ...(DNS) system with an eccentricity of 0.089. From radio timing with the Arecibo 305 m telescope, we measure the rate of advance of periastron to be ° yr−1. Assuming general relativity accurately models the orbital motion, this corresponds to a total system mass of Mtot = 2.875(14) , similar to the mass of the most massive DNS known to date, B1913+16, but with a much smaller eccentricity. The small eccentricity indicates that the second-formed neutron star (NS) (the companion of PSR J1913+1102) was born in a supernova with a very small associated kick and mass loss. In that case, this companion is likely, by analogy with other systems, to be a light (∼1.2 ) NS; the system would then be highly asymmetric. A search for radio pulsations from the companion yielded no plausible detections, so we cannot yet confirm this mass asymmetry. By the end of 2016, timing observations should permit the detection of two additional post-Keplerian parameters: the Einstein delay (γ), which will enable precise mass measurements and a verification of the possible mass asymmetry of the system, and the orbital decay due to the emission of gravitational waves ( ), which will allow another test of the radiative properties of gravity. The latter effect will cause the system to coalesce in ∼0.5 Gyr.
During laparotomy, surgeons may experience difficult surgical conditions if the patient's abdominal wall or diaphragm is tense. Deep neuromuscular block (NMB), defined as a post-tetanic-count (PTC) ...between 0-1, paralyses the abdominal wall muscles and the diaphragm. We hypothesized that deep NMB (PTC 0-1) would improve subjective ratings of surgical conditions during upper laparotomy as compared with standard NMB.
This was a double blinded, randomized study. A total of 128 patients undergoing elective upper laparotomy were randomized to either continuous deep NMB (infusion of rocuronium 2 mg ml−1) or standard NMB (bolus of rocuronium 10 mg or increased depth of anaesthesia). Surgical conditions were evaluated using a 5-point subjective rating scale (1: extremely poor, 5: optimal) every 30 min. Primary outcome was the average of scores for a patient's surgical conditions. Other outcomes were surgical rating score during fascial closure, episodes of a need to optimize surgical conditions, occurrence of wound dehiscence, and wound infection.
Deep compared with standard NMB resulted in better ratings of surgical conditions; median 4.75 (range 3–5) compared with 4.00 (range 1–5) (P<0.001), respectively. Deep compared with standard NMB resulted in better ratings of surgical conditions during fascial closure (P<0.001), fewer episodes of need to optimize surgical conditions (P<0.001), and fewer incidents with sudden movements (P<0.001). No differences in operating time, occurrence of wound infection, and wound dehiscence were found.
Deep NMB compared with standard NMB resulted in better subjective ratings of surgical conditions during laparotomy.
NCT02140593.
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Increasing levels of distributed generation (DG), as well as changes in electricity consumption behavior, are reshaping power distribution systems. These changes might place particular stress on the ...secondary low-voltage (LV) distribution systems not originally designed for bi-directional power flows. Voltage violations, reverse power flow, and congestion are the main arising concerns for distribution system operators (DSOs), while observability in these grids is typically nonexistent or very low. The present paper addresses this issue by developing a method for nodal voltage estimation in unbalanced radial LV grids (at 0.4 kV). The workflow of the proposed method combines a data-driven grey-box modeling approach with generalized additive models (GAMs). Furthermore, the proposed method relies on experimental data from a real-world LV grid in Denmark and uses data input from only one measuring device per feeder. Predictions are evaluated by using a test data set of 31 days, which is more than twice the size of the training data set of 13 days. The prediction results show high accuracy at root mean squared errors (RMSEs) of 0.002–0.0004 p.u. The method also requires a short computation time (14 s for the first stage and 2 s for the second stage) that meets requirements for the practical, real-time monitoring of DSO grids.
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ABSTRACT The on-going Arecibo Pulsar-ALFA (PALFA) survey began in 2004 and is searching for radio pulsars in the Galactic plane at 1.4 GHz. Here we present a comprehensive description of one of its ...main data reduction pipelines that is based on the PRESTO software and includes new interference-excision algorithms and candidate selection heuristics. This pipeline has been used to discover 40 pulsars, bringing the survey's discovery total to 144 pulsars. Of the new discoveries, eight are millisecond pulsars (MSPs; ms) and one is a Fast Radio Burst (FRB). This pipeline has also re-detected 188 previously known pulsars, 60 of them previously discovered by the other PALFA pipelines. We present a novel method for determining the survey sensitivity that accurately takes into account the effects of interference and red noise: we inject synthetic pulsar signals with various parameters into real survey observations and then attempt to recover them with our pipeline. We find that the PALFA survey achieves the sensitivity to MSPs predicted by theoretical models but suffers a degradation for ms that gradually becomes up to ∼10 times worse for at pc cm−3. We estimate 33 3% of the slower pulsars are missed, largely due to red noise. A population synthesis analysis using the sensitivity limits we measured suggests the PALFA survey should have found 224 16 un-recycled pulsars in the data set analyzed, in agreement with the 241 actually detected. The reduced sensitivity could have implications on estimates of the number of long-period pulsars in the Galaxy.
Background
Deep neuromuscular blockade during laparoscopic surgery may provide some clinical benefit. We present the ‘Pro‐’ argument in this paired position paper.
Methods
We reviewed recent evidence ...from a basic database of references which we agreed on with the ‘Con‐’ side, and present this in narrative form. We have shared our analysis and text with the authors of the ‘Con‐’ side of these paired position papers during the preparation of the manuscripts.
Results
There are a few low risk of bias studies indicating that use of deep neuromuscular blockade improve surgical conditions and improve patient outcomes such as post‐operative pain in laparoscopic surgery.
Conclusion
Our interpretation of recent findings is that there is reason to believe that there may be some patient benefit of deep neuromuscular blockade in this context, and more detailed study is needed.
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•Saliva metabolome was explored for potential biomarkers for gastric ulcers in pigs.•Effects of hemp products on incidence of gastric ulcers were examined.•Oxylipins derived from linoleic acid seemed ...to be associated with gastric ulcers.•Salivary oxylipins might function as biomarkers for gastric ulceration in pigs.•Hemp hulls may reduce the incidence of severe gastric ulcers in pigs.
Gastric ulceration is a common disease in pig production worldwide and is associated with economic losses as well as animal health and welfare issues. The aim of this study was to explore potential salivary biomarkers for gastric ulceration in pigs. In addition, the aim was to study the effect of hemp on the incidence of gastric ulcers. Approximately 440 growing-finishing pigs in the period from 30 to 110 kg BW were allocated to four different diets: meal feed (Meal); pelleted feed (Pellets); pelleted feed added 4% hempseed cake (Hemp Cake); pelleted feed added 4% hempseed hulls (Hemp Hulls). The day before slaughter, saliva samples from each pig were collected. After slaughter, the stomachs were emptied to assess the consistency of the stomach content and examined for gastric ulceration using an index scale (0–10). Noticeable changes of the gastric mucosa (total index score ≥ 6) were observed in 291 pigs. The odds of having index scores 0–5 relative to index scores 6–8 and 9–10, respectively, were higher (P < 0.001) for pigs fed Meal compared to pigs fed Pellets. The odds of suffering from severe gastric ulcers tended (P = 0.08) to be lower in pigs fed Hemp Hulls compared to pigs fed Pellets. A non-targeted liquid chromatography mass spectrometry based metabolomics analysis was performed on saliva samples to determine any separation between pigs with healthy stomachs and those with gastric ulcers and to examine a possible correlation between gastric ulcer index and potential biomarkers. Partial least-squares discriminant analysis showed a separation between pigs with ulcers and those with healthy stomachs/hyperkeratosis (HK). Metabolites contributing to the separation between groups were identified. Levels of oxylipins deriving from linoleic acid were lower (P < 0.001) in pigs with ulcers compared to healthy/HK pigs. This may indicate a shift in the metabolic pathways towards more pro-inflammatory arachidonic acid-derived eicosanoids, which might reflect an increased inflammatory response. Thus, reduced levels of oxylipins derived from linoleic acid seemed to be associated with active gastric ulcers, and thereby they might function as biomarkers for gastric ulceration in pigs. In addition, supplementation of hempseed hulls had a beneficial effect on severe gastric ulcers, as hempseed hulls changed the consistency of the gastric content by conferring more solidness. However, it was not possible to observe any reliable separation between pigs fed pellets supplemented with hemp products and pigs fed non-supplemented pellets according to the identified salivary metabolites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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