ABSTRACT To date, the Burst Alert Telescope (BAT) onboard Swift has detected ∼1000 gamma-ray bursts (GRBs), of which ∼360 GRBs have redshift measurements, ranging from z = 0.03 to z = 9.38. We ...present the analyses of the BAT-detected GRBs for the past ∼11 years up through GRB 151027B. We report summaries of both the temporal and spectral analyses of the GRB characteristics using event data (i.e., data for each photon within approximately 250 s before and 950 s after the BAT trigger time), and discuss the instrumental sensitivity and selection effects of GRB detections. We also explore the GRB properties with redshift when possible. The result summaries and data products are available at http://swift.gsfc.nasa.gov/results/batgrbcat/index.html. In addition, we perform searches for GRB emissions before or after the event data using the BAT survey data. We estimate the false detection rate to be only one false detection in this sample. There are 15 ultra-long GRBs (∼2% of the BAT GRBs) in this search with confirmed emission beyond ∼1000 s of event data, and only two GRBs (GRB 100316D and GRB 101024A) with detections in the survey data prior to the starting of event data.
he burst alert telescope (BAT) is one of three instruments on the Swift MIDEX spacecraft to study gamma-ray bursts (GRBs). The BAT first detects the GRB and localizes the burst direction to an ...accuracy of 1-4 arcmin within 20 s after the start of the event. The GRB trigger initiates an autonomous spacecraft slew to point the two narrow field-of-view (FOV) instruments at the burst location within 20-70 s so to make follow-up X-ray and optical observations. The BAT is a wide-FOV, coded-aperture instrument with a CdZnTe detector plane. The detector plane is composed of 32,768 pieces of CdZnTe (4×4×2 mm), and the coded-aperture mask is composed of 52,000 pieces of lead (5×5×1 mm) with a 1-m separation between mask and detector plane. The BAT operates over the 15-150 keV energy range with 7 keV resolution, a sensitivity of 10^sup -8^ erg s^sup -1^ cm^sup -2^, and a 1.4 sr (half-coded) FOV. We expect to detect > 100 GRBs/year for a 2-year mission. The BAT also performs an all-sky hard X-ray survey with a sensitivity of 2 m Crab (systematic limit) and it serves as a hard X-ray transient monitor.PUBLICATION ABSTRACT
During the New Horizons spacecraft's encounter with Pluto, the Alice ultraviolet spectrograph conducted a series of observations that detected emissions from both the interplanetary medium (IPM) and ...Pluto. In the direction of Pluto, the IPM was found to be 133.4 0.6 R at Ly , 0.24 0.02 R at Lyβ, and <0.10 R at He i 584 . We analyzed 3900 s of data obtained shortly before closest approach to Pluto and detect airglow emissions from H i, N i, N ii, N2, and CO above the disk of Pluto. We find Pluto's brightness at Ly to be 29.3 1.9 R, in good agreement with preencounter estimates. The detection of the N ii multiplet at 1085 marks the first direct detection of ions in Pluto's atmosphere. We do not detect any emissions from noble gases and place a 3 upper limit of 0.14 R on the brightness of the Ar i 1048 line. We compare preencounter model predictions and predictions from our own airglow model, based on atmospheric profiles derived from the solar occultation observed by New Horizons, to the observed brightness of Pluto's airglow. Although completely opaque at Ly , Pluto's atmosphere is optically thin at wavelengths longer than 1425 . Consequently, a significant amount of solar far-UV light reaches the surface, where it can participate in space weathering processes. From the brightness of sunlight reflected from Pluto, we find the surface has a reflectance factor (I/F) of 17% between 1400 and 1850 . We also report the first detection of a C3 hydrocarbon molecule, methylacetylene, in absorption, at a column density of ∼5 × 1015 cm−2, corresponding to a column-integrated mixing ratio of 1.6 × 10−6.
The double burst, GRB 110709B, triggered the Swift/Burst Alert Telescope (BAT) twice at 21:32:39 UT and 21:43:45 UT, respectively, on 2011 July 9. This is the first time we observed a gamma-ray burst ...(GRB) with two BAT triggers. In this paper, we present simultaneous Swift and Konus-WIND observations of this unusual GRB and its afterglow. If the two events originated from the same physical progenitor, their different time-dependent spectral evolution suggests they must belong to different episodes of the central engine, which may be a magnetar-to-BH accretion system.
GRB 090417B was an unusually long burst with a T{sub 90} duration of at least 2130 s and a multi-peaked light curve at energies of 15-150 keV. It was optically dark and has been associated with a ...bright star-forming galaxy at a redshift of 0.345 that is broadly similar to the Milky Way. This is one of the few cases where a host galaxy has been clearly identified for a dark gamma-ray burst (GRB) and thus an ideal candidate for studying the origin of dark bursts. We find that the dark nature of GRB 090417B cannot be explained by high redshift, incomplete observations, or unusual physics in the production of the afterglow. Assuming the standard relativistic fireball model for the afterglow we find that the optical flux is at least 2.5 mag fainter than predicted by the X-ray flux. The Swift/XRT X-ray data are consistent with the afterglow being obscured by a dense, localized sheet of dust approximately 30-80 pc from the burst along the line of sight. Our results suggest that this dust sheet imparts an extinction of A{sub V} {approx_gt} 12 mag, which is sufficient to explain the missing optical flux. GRB 090417B is an example of a GRBs that is dark due to the localized dust structure in its host galaxy.
We report on the spectral cross-calibration results of the Konus-Wind, the Suzaku/WAM, and the Swift/BAT instruments using simultaneously observed gamma-ray bursts (GRBs). This is the first attempt ...to use simultaneously observed GRBs as a spectral calibration source to understand systematic problems among the instruments. Based on these joint spectral fits, we find that (1) although a constant factor (a normalization factor) agrees within 20% among the instruments, the BAT constant factor shows a systematically smaller value by 10%–20% compared to that of Konus-Wind, (2) there is a systematic trend that the low-energy photon index becomes steeper by 0.1–0.2 and
$E_{\rm peak}$
becomes systematically higher by 10%–20% when including the BAT data in the joint fits, and (3) the high-energy photon index agrees within 0.2 among the instruments. Our results show that cross-calibration based on joint spectral analysis is an important step to understanding the instrumental effects that could be affecting the scientific results from the GRB prompt emission data.
Pain and gastrointestinal dysfunction are primary factors that delay recovery after posterior spinal fusion. Previous reports suggest that the choice of analgesic management may effect the course of ...recovery. This prospective, randomized study compared continuous thoracic epidural analgesia and patient-controlled analgesia in the postoperative care of adolescents undergoing posterior spinal fusion for idiopathic scoliosis.
Patients between 11 and 18 years of age were randomized to receive continuous thoracic epidural analgesia with bupivacaine-fentanyl (CEA, n = 17) or intravenous patient-controlled analgesia with morphine sulfate (n = 16). After surgery under general anesthesia, pain intensity was evaluated using a self-report visual analog scale (VAS). Postoperative time to resumption of bowel sounds, liquid intake, and side effects were also recorded.
There were no significant differences between groups in VAS pain scores, side effects, or time to resumption of liquid intake. There was a significant difference (P = .0089) between groups in return of bowel sounds, which occurred earlier in patients receiving CEA.
Continuous epidural analgesia and patient-controlled analgesia are comparably effective and safe after posterior spinal fusion. Return of bowel sounds occurred significantly more rapidly in patients receiving CEA postoperatively.
We performed a case-control study to determine whether occult bone disease is associated with a history of frequent fractures in children.
Healthy children with > or = 2 incidences of low-energy ...fractures were recruited (n = 68). Children with no history of fractures served as control subjects (n = 57). Food logs, activity surveys, physical examinations, laboratory tests, and dual-energy radiographic absorptiometry were used.
Bone mineral density z scores were significantly reduced in case subjects, compared with control subjects. Three case subjects (4.3%) and 1 control subject (1.8%) had bone mineral density z scores below the expected range. Of those 4 subjects, 2 had dairy avoidance and 2 had delayed puberty. An additional case subject had evidence of vitamin D deficiency. A significant number of subjects (20% of case subjects and 23% of control subjects) had idiopathic hypercalcuria, based on 24-hour urine collections. Among the case subjects, bone mineral density z scores were significantly lower for those with idiopathic hypercalcuria. Among the control subjects, the presence of idiopathic hypercalcuria did not affect bone mineral density. The case subjects with idiopathic hypercalcuria accounted for virtually all of the differences in bone mineral density between the case and control groups. Analysis of parathyroid hormone and 1,25-dihydroxy-vitamin D levels showed that children with frequent fractures and hypercalcuria had renal hypercalcuria, whereas children with no fractures and hypercalcuria had absorptive hypercalcuria.
We identified a significant association between a history of frequent fractures and hypercalcuria in children. We propose that the appropriate screening evaluation for children who present with a history of frequent fractures consists of a dietary history targeted at calcium and vitamin D intakes, a physical examination to assess for pubertal delay, and urinary calcium concentration/creatinine ratio determination to assess for hypercalcuria. Children with abnormalities in this screening should undergo dual-energy radiographic absorptiometry and appropriate evaluation.
Paediatric femoral fracture Cummings, R Jay
The Lancet (British edition),
03/2005, Volume:
365, Issue:
9465
Journal Article
Peer reviewed
In this issue of The Lancet, James Wright and colleagues report a multicentre randomised trial comparing external fixation to early hip-spica casting for the treatment of paediatric femoral shaft ...fractures. Randomised trials of surgical treatments such as that reported by Wright and colleagues are difficult to do. After parents are informed of the advantages and disadvantages of the various treatments to be studied, they often decline to participate in the randomisation because they are reluctant to give up their right to choose the method that has a set of complications and inconveniences that are most acceptable to them. Because there are few other randomised studies that compare the various treatments of paediatric femoral shaft fractures, Wright's study is important.
The classification of adolescent idiopathic scoliosis with use of the system of King et al. has become widely accepted since its introduction. The purpose of the present study was to establish the ...interobserver reliability and intraobserver reproducibility of this classification system. The preoperative radiographs of sixty-three patients who were managed operatively for adolescent idiopathic scoliosis were classified by five observers with the system of King et al. Interobserver reliability was assessed by comparison of the classification of the curves among the observers, and intraobserver reproducibility was evaluated by comparison of the classifications of each set of radiographs by each observer on two occasions three weeks apart. The median interobserver reliability kappa coefficient for the classification system of King et al. was 0.44 (range, 0.28 to 0.50), and the median intraobserver reproducibility kappa coefficient was 0.64 (range, 0.44 to 0.72). According to the definition of Landis and Koch, the classification system of King et al. is substantially reproducible but is only moderately reliable. However, according to the stricter definition of Svanholm et al., its reproducibility is only fair and its reliability is poor.
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