11 research outputs found
Magneto--Acoustic Energetics Study of the Seismically Active Flare of 15 February 2011
Multi--wavelength studies of energetic solar flares with seismic emissions
have revealed interesting common features between them. We studied the first
GOES X--class flare of the 24th solar cycle, as detected by the Solar Dynamics
Observatory (SDO). For context, seismic activity from this flare
(SOL2011-02-15T01:55-X2.2, in NOAA AR 11158) has been reported in the
literature (Kosovichev, 2011; Zharkov et al., 2011). Based on Dopplergram data
from the Helioseismic and Magnetic Imager (HMI), we applied standard methods of
local helioseismology in order to identify the seismic sources in this event.
RHESSI hard X-ray data are used to check the correlation between the location
of the seismic sources and the particle precipitation sites in during the
flare. Using HMI magnetogram data, the temporal profile of fluctuations in the
photospheric line-of-sight magnetic field is used to estimate the magnetic
field change in the region where the seismic signal was observed. This leads to
an estimate of the work done by the Lorentz-force transient on the photosphere
of the source region. In this instance this is found to be a significant
fraction of the acoustic energy in the attendant seismic emission, suggesting
that Lorentz forces can contribute significantly to the generation of
sunquakes. However, there are regions in which the signature of the
Lorentz-force is much stronger, but from which no significant acoustic emission
emanates.Comment: Submitted to Solar Physic
A statistical correlation of sunquakes based on their seismic and white-light emission
Several mechanisms have been proposed to explain the transient seismic emission, i.e. âsunquakes,â from some solar flares. Some theories associate high-energy electrons and/or white-light emission with sunquakes. High-energy charged particles and their subsequent heating of the photosphere and/or chromosphere could induce acoustic waves in the solar interior. We carried out a correlative study of solar flares with emission in hard X-rays, enhanced continuum emission at 6173 Ă
, and transient seismic emission. We selected those flares observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) with a considerable flux above 50 keV between 1 January 2010 and 26 June 2014. We then used data from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory to search for excess visible-continuum emission and new sunquakes not previously reported. We found a total of 18 sunquakes out of 75 flares investigated. All of the sunquakes were associated with an enhancement of the visible continuum during the flare. Finally, we calculated a coefficient of correlation for a set of dichotomic variables related to these observations. We found a strong correlation between two of the standard helioseismic detection techniques, and between sunquakes and visible-continuum enhancements. We discuss the phenomenological connectivity between these physical quantities and the observational difficulties of detecting seismic signals and excess continuum radiation
Trends and outcome of neoadjuvant treatment for rectal cancer: A retrospective analysis and critical assessment of a 10-year prospective national registry on behalf of the Spanish Rectal Cancer Project
Introduction: Preoperative treatment and adequate surgery increase local control in rectal cancer. However, modalities and indications for neoadjuvant treatment may be controversial. Aim of this study was to assess the trends of preoperative treatment and outcomes in patients with rectal cancer included in the Rectal Cancer Registry of the Spanish Associations of Surgeons.
Method: This is a STROBE-compliant retrospective analysis of a prospective database. All patients operated on with curative intention included in the Rectal Cancer Registry were included. Analyses were performed to compare the use of neoadjuvant/adjuvant treatment in three timeframes: I)2006â2009; II)2010â2013; III)2014â2017. Survival analyses were run for 3-year survival in timeframes I-II.
Results: Out of 14, 391 patients, 8871 (61.6%) received neoadjuvant treatment. Long-course chemo/radiotherapy was the most used approach (79.9%), followed by short-course radiotherapy ± chemotherapy (7.6%). The use of neoadjuvant treatment for cancer of the upper third (15-11 cm) increased over time (31.5%vs 34.5%vs 38.6%, p = 0.0018). The complete regression rate slightly increased over time (15.6% vs 16% vs 18.5%; p = 0.0093); the proportion of patients with involved circumferential resection margins (CRM) went down from 8.2% to 7.3%and 5.5% (p = 0.0004). Neoadjuvant treatment significantly decreased positive CRM in lower third tumors (OR 0.71, 0.59â0.87, Cochrane-Mantel-Haenszel P = 0.0008). Most ypN0 patients also received adjuvant therapy. In MR-defined stage III patients, preoperative treatment was associated with significantly longer local-recurrence-free survival (p < 0.0001), and cancer-specific survival (p < 0.0001). The survival benefit was smaller in upper third cancers.
Conclusion: There was an increasing trend and a potential overuse of neoadjuvant treatment in cancer of the upper rectum. Most ypN0 patients received postoperative treatment. Involvement of CRM in lower third tumors was reduced after neoadjuvant treatment. Stage III and MRcN + benefited the most
Changes in soil physical properties alter conversiĂłn of tropical montane cloud forest to pasture in northern Costa Rica
Sediment-Trapping by Beaver Ponds in Streams of the Mid-Atlantic Piedmont and Coastal Plain, USA
International Nosocomial Infection Control Consortium report, data summary of 50 countries for 2010-2015: Device-associated module
âąWe report INICC device-associated module data of 50 countries from 2010-2015.âąWe collected prospective data from 861,284 patients in 703 ICUs for 3,506,562 days.âąDA-HAI rates and bacterial resistance were higher in the INICC ICUs than in CDC-NHSN's.âąDevice utilization ratio in the INICC ICUs was similar to CDC-NHSN's.
Background: We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2010-December 2015 in 703 intensive care units (ICUs) in Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific.
Methods: During the 6-year study period, using Centers for Disease Control and Prevention National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI), we collected prospective data from 861,284 patients hospitalized in INICC hospital ICUs for an aggregate of 3,506,562 days.
Results: Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the INICC medical-surgical ICUs, the pooled rate of central line-associated bloodstream infection, 4.1 per 1,000 central line-days, was nearly 5-fold higher than the 0.8 per 1,000 central line-days reported from comparable US ICUs, the overall rate of ventilator-associated pneumonia was also higher, 13.1 versus 0.9 per 1,000 ventilator-days, as was the rate of catheter-associated urinary tract infection, 5.07 versus 1.7 per 1,000 catheter-days. From blood cultures samples, frequencies of resistance of Pseudomonas isolates to amikacin (29.87% vs 10%) and to imipenem (44.3% vs 26.1%), and of Klebsiella pneumoniae isolates to ceftazidime (73.2% vs 28.8%) and to imipenem (43.27% vs 12.8%) were also higher in the INICC ICUs compared with CDC-NHSN ICUs.
Conclusions: Although DA-HAIs in INICC ICU patients continue to be higher than the rates reported in CDC-NSHN ICUs representing the developed world, we have observed a significant trend toward the reduction of DA-HAI rates in INICC ICUs as shown in each international report. It is INICC's main goal to continue facilitating education, training, and basic and cost-effective tools and resources, such as standardized forms and an online platform, to tackle this problem effectively and systematically
Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study
International audienceBackground: Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods: WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings: Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0â4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (â€1 day), 457 (10·1%) had intermediate weaning (2â6 days), 433 (9·6%) required prolonged weaning (â„7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation: In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates. Funding: European Society of Intensive Care Medicine, European Respiratory Society