CMS has a two level trigger system. The first stage is hardware based and provides fast trigger decisions up to a rate 100 kHz. The second stage, known as the High-Level Trigger, is entirely software ...based and required to provide a trigger decision within 40 ms and a rejection factor of a thousand to achieve a write-to-disk rate of 100 Hz. One of the most CPU-intensive tasks within the High-Level Trigger is the reconstruction of tracking hits using raw data from the strip tracker. This study profiles the performance of these reconstruction algorithms. Even at low luminosities, the average processing time is 5.5 s, which already exceeds the HLT budget. A new schema, optimised for speed and performance, has been developed to reconstruct hits within regions-of-interest only. For the entire sub-detector, hit reconstruction times are reduced to 140 ms. Since only 10 % of High-Level Trigger events are expected to require track reconstruction, the average contribution per event is then ∼14 ms i.e. 30 % of the full budget. Regional reconstruction is tested over Z0 → e+e− events, by unpacking in η-φ windows of 0.16 × 0.16 around seeds identified in the calorimeter. In this case, only 2 ± 1 % of the silicon strip tracker raw data is reconstructed in 5 ± 3 ms (or an average contribution per event of 0.5 ms) whilst maintaining 99 % of the original dielectron trigger efficiency.
The CMS silicon strip tracker, providing a sensitive area of approximately 200 m2 and comprising 10 million readout channels, has recently been completed at the tracker integration facility at CERN. ...The strip tracker community is currently working to develop and integrate the online and offline software frameworks, known as XDAQ and CMSSW respectively, for the purposes of data acquisition and detector commissioning and monitoring. Recent developments have seen the integration of many new services and tools within the online data acquisition system, such as event building, online distributed analysis, an online monitoring framework, and data storage management. We review the various software components that comprise the strip tracker data acquisition system, the software architectures used for stand-alone and global data-taking modes. Our experiences in commissioning and operating one of the largest ever silicon micro-strip tracking systems are also reviewed.
The CMS Silicon Strip Tracker at the LHC comprises a sensitive area of approximately 200 m2 and 10 million readout channels. Its data acquisition system is based around a custom analogue front-end ...chip. Both the control and the readout of the front-end electronics are performed by off-detector VME boards in the counting room, which digitise the raw event data and perform zero-suppression and formatting. The data acquisition system uses the CMS online software framework to configure, control and monitor the hardware components and steer the data acquisition. The first data analysis is performed online within the official CMS reconstruction framework, which provides many services, such as distributed analysis, access to geometry and conditions data, and a Data Quality Monitoring tool based on the online physics reconstruction. The data acquisition monitoring of the Strip Tracker uses both the data acquisition and the reconstruction software frameworks in order to provide real-time feedback to shifters on the operational state of the detector, archiving for later analysis and possibly trigger automatic recovery actions in case of errors. Here we review the proposed architecture of the monitoring system and we describe its software components, which are already in place, the various monitoring streams available, and our experiences of operating and monitoring a large-scale system.
A study was made of the photochemical degradation of copper complexes of nitrilotriacetate that may occur under sunlight irradiation by irradiating solutions of copper complexes in distilled water, ...and in water from the Rideau river, Ont., at 350 nm in a photoreactor based on a Rayonet unit. The results, presented with graphs, indicate that significant photodecomposition of the ligand occurs; formaldehyde and iminodiacetic acid are produced during the reaction and carbon dioxide is released.
We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic ...adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods—especially in Greenland and West Antarctica—and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -152 ± 49, +14 ± 43, -65 ± 26, and -20 ± 14 gigatonnes year⁻¹, respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year⁻¹ to the rate of global sea-level rise.
The existence of many subglacial lakes provides clear evidence for the widespread presence of water beneath the East Antarctic ice sheet, but the hydrology beneath this ice mass is poorly understood. ...Such knowledge is critical to understanding ice flow, basal water transfer to the ice margin, glacial landform development and subglacial lake habitats. Here we present ice-sheet surface elevation changes in central East Antarctica that we interpret to represent rapid discharge from a subglacial lake. Our observations indicate that during a period of 16 months, 1.8 km3 of water was transferred over 290 km to at least two other subglacial lakes. While viscous deformation of the ice roof above may moderate discharge, the intrinsic instability of such a system suggests that discharge events are a common mode of basal drainage. If large lakes, such as Lake Vostok or Lake Concordia, are pressurizing, it is possible that substantial discharges could reach the coast. Our observations conflict with expectations that subglacial lakes have long residence times and slow circulations, and we suggest that entire subglacial drainage basins may be flushed periodically. The rapid transfer of water between lakes would result in large-scale solute and microbe relocation, and drainage system contamination from in situ exploration is, therefore, a distinct risk.
Background
Cardiac rehabilitation improves health-related quality of life (HRQoL) and reduces hospitalizations in patients with heart failure, but international uptake of cardiac rehabilitation for ...heart failure remains low.
Design and methods
The aim of this multicentre randomized trial was to compare the REACH-HF (Rehabilitation EnAblement in CHronicHeart Failure) intervention, a facilitated self-care and home-based cardiac rehabilitation programme to usual care for adults with heart failure with reduced ejection fraction (HFrEF). The study primary hypothesis was that the addition of the REACH-HF intervention to usual care would improve disease-specific HRQoL (Minnesota Living with Heart Failure questionnaire (MLHFQ)) at 12 months compared with usual care alone.
Results
The study recruited 216 participants, predominantly men (78%), with an average age of 70 years and mean left ventricular ejection fraction of 34%. Overall, 185 (86%) participants provided data for the primary outcome. At 12 months, there was a significant and clinically meaningful between-group difference in the MLHFQ score of –5.7 points (95% confidence interval –10.6 to –0.7) in favour of the REACH-HF intervention group (p = 0.025). With the exception of patient self-care (p < 0.001) there was no significant difference in other secondary outcomes, including clinical events (p > 0.05) at follow-up compared with usual care. The mean cost of the REACH-HF intervention was £418 per participant.
Conclusions
The novel REACH-HF home-based facilitated intervention for HFrEF was clinically superior in disease-specific HRQoL at 12 months and offers an affordable alternative to traditional centre-based programmes to address current low cardiac rehabilitation uptake rates for heart failure.
This paper investigates the conditions under which a marine ice sheet may adopt a steady profile. The ice is treated as a linear viscous fluid caused to flow from a rigid base to and over water, ...treated as a denser but inviscid fluid. The solutions in the region around the point of flotation, or ‘transition’ zone, are calculated numerically. In-flow and out-flow conditions appropriate to ice sheet and ice shelf flow are applied at the ends of the transition zone and the rigid base is specified; the flow and steady free surfaces are determined as part of the solutions. The basal stress upstream, and the basal deflection downstream, of the flotation point are examined to determine which of these steady solutions satisfy ‘contact’ conditions that would prevent (i) the steady downstream basal deflection contacting the downstream base, and (ii) the upstream ice commencing to float in the event it was melted at the base. In the case that the upstream bed is allowed to slide, we find only one mass flux that satisfies the contact conditions. When no sliding is allowed at the bed, however, we find a range of mass fluxes satisfy the contact conditions. The effect of ‘backpressure’ on the solutions is investigated, and is found to have no affect on the qualitative behaviour of the junctions. To the extent that the numerical, linearly viscous treatment may be applied to the case of ice flowing out over the ocean, we conclude that when sliding is present, Weertman's ‘instability’ hypothesis holds.
Abstract We report the discovery of the transiting planet GJ 238 b, with a radius of 0.566 ± 0.014 R ⊕ (1.064 ± 0.026 times the radius of Mars) and an orbital period of 1.74 days. The transit signal ...was detected by the TESS mission and designated TOI-486.01. The star’s position close to the southern ecliptic pole allows for almost continuous observations by TESS when it is observing the southern sky. The host star is an M2.5 dwarf with V = 11.57 ± 0.02 mag, K = 7.030 ± 0.023 mag, a distance of 15.2156 ± 0.0030 pc, a mass of 0.4193 − 0.0098 + 0.0095 M ☉ , a radius of 0.4314 − 0.0071 + 0.0075 R ☉ , and an effective temperature of 3485 ± 140 K. We validate the planet candidate by ruling out or rendering highly unlikely each of the false positive scenarios, based on archival data and ground-based follow-up observations. Validation was facilitated by the host star’s small size and high proper motion of 892.633 ± 0.025 mas yr –1 .
This paper describes the calibration of the CryoSat-2 interferometer, whose principal purpose is to accurately measure the height of the Antarctic and Greenland ice sheets. A sequence of CryoSat-2 ...data acquisitions over the tropical and midlatitude oceans were obtained between June and September 2010, from the SIRAL "A" and redundant SIRAL "B" radars operating in their "SARIN" mode, during a sequence of satellite rolls between -0.6° and 0.4°. Using the arrival angle of the echo relative to the interferometer baseline, the attitude of the satellite determined by the star trackers, and estimates of the ocean surface across-track slope from the EGM08 geoid, we determined the errors in the interferometer estimate of surface slope as functions of the roll angle and ocean surface waveheight. These were found to be in close agreement with the theoretical description. The scale factor of the interferometric measurement of angle was determined to be 0.973 ± 0.002. We estimate the accuracy of the across-track slope measurement of the interferometer by applying this scale factor to the measured phase. In applying this scale factor to the measurements, the across-track slope of the marine geoid was obtained with an accuracy of 26 μrad at 10 km and 10 μrad at 1000 km. We conclude that the instrument performance considerably exceeds that needed for the accurate determination of height over the sloping surfaces of the continental ice sheets. The results also demonstrate that CryoSat-2 provides the first observations of the instantaneous vector gradient of the ocean surface, and that the normal-incidence interferometric configuration has a greater potential for the measurement of the ocean across-track slope than has been previously recognized.
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