502 research outputs found
Comparative Outcomes of Resident vs Attending Performed Surgery: A Systematic Review and Meta-Analysis
OBJECTIVE: To determine whether outcomes are different when surgery is performed by resident or attending surgeons, and which variables may affect outcomes. DESIGN: MEDLINE, EMBASE, and the Cochrane Library were searched from inception to May 2014 alongside the bibliographies of all included or relevant studies. Any study comparing outcomes from surgery performed by resident vs attending surgeons was eligible for inclusion. The main outcome measures were surgical complications (classified by Clavien-Dindo grade), death, operative time, and length of stay. Data were extracted independently by 2 authors and analyzed using the random-effects model. RESULTS: The final analysis included 182 eligible studies that enrolled 141 555 patients. Resident performed surgery took longer by 10.2 minutes (95% confidence interval (CI): 8.38-11.95), and had more Clavien-Dindo grade 1 (rate ratio = 1.14, 95% CI: 1.02-1.29) and grade 3a complications (rate ratio = 1.22, 95% CI: 1.04-1.44). Resident performed surgery resulted in fewer deaths (risk ratio = 0.83, 95% CI: 0.70-0.999) with a shorter length of stay of -0.49 days (95% CI: -0.77 to -0.21). Significant heterogeneity was present in 7 of 10 outcomes, which persisted during multiple subgroup analyses. CONCLUSIONS: Resident performed surgery appears to be safe in carefully selected patients. The significant amount of heterogeneity present in the study outcomes prevents generalizability of these results to specific clinical contexts
Towards the high-accuracy determination of the 238U fission cross section at the threshold region at CERN - N-TOF
The 238U fission cross section is an international standard beyond 2 MeV where the fission plateau starts. However, due to its importance in fission reactors, this cross-section should be very accurately known also in the threshold region below 2 MeV. The 238U fission cross section has been measured relative to the 235U fission cross section at CERN - n-TOF with different detection systems. These datasets have been collected and suitably combined to increase the counting statistics in the threshold region from about 300 keV up to 3 MeV. The results are compared with other experimental data, evaluated libraries, and the IAEA standards
High accuracy 234U(n,f) cross section in the resonance energy region
New results are presented of the 234U neutron-induced fission cross section, obtained with high accuracy in the resonance region by means of two methods using the 235U(n,f) as reference. The recent evaluation of the 235U(n,f) obtained with SAMMY by L. C. Leal et al. (these Proceedings), based on previous n-TOF data [1], has been used to calculate the 234U(n,f) cross section through the 234U/235U ratio, being here compared with the results obtained by using the n-TOF neutron flux
Ni-62(n,gamma) and Ni-63(n,gamma) cross sections measured at the n_TOF facility at CERN
The cross section of the Ni-62(n,gamma) reaction was measured with the time-of-flight technique at the neutron time-of-flight facility n_TOF at CERN. Capture kernels of 42 resonances were analyzed up to 200 keV neutron energy and Maxwellian averaged cross sections (MACS) from kT = 5-100 keV were calculated. With a total uncertainty of 4.5%, the stellar cross section is in excellent agreement with the the KADoNiS compilation at kT = 30 keV, while being systematically lower up to a factor of 1.6 at higher stellar temperatures. The cross section of the Ni-63(n,gamma) reaction was measured for the first time at n_TOF. We determined unresolved cross sections from 10 to 270 keV with a systematic uncertainty of 17%. These results provide fundamental constraints on s-process production of heavier species, especially the production of Cu in massive stars, which serve as the dominant source of Cu in the solar system.Peer reviewedFinal Accepted Versio
Tailoring cassava starch properties: A study on Heat-Moisture Treatment (HMT) and Annealing (ANN) for enhanced functional applications
Native cassava starch was subjected to HMT and ANN under varying temperature and treatment duration conditions, as designed using a response surface methodology. The physicochemical properties of the modified starch were compared to those of native starch. The two treatments resulted in distinct alterations of the starch properties. HMT and ANN caused changes in solubility, swelling power, pasting properties, freeze-thaw stability, water and oil absorption capacities, water activity, colour and gelatinization characteristics. Solubility increased by 1.4 % and 3.81 % under HMT 25 % and HMT 30 % respectively, whereas ANN at 1: 3 starch-to-water ratio reduced solubility by 4.02 % compared to untreated starch. Swelling power decreased in the modified starch compared to the control sample. Viscosity studies revealed that peak viscosity decreased from 3812 cP in untreated sample to 3267 cP and 3150 cP after HMT - 25 % and HMT - 30 % respectively. In contrast, ANN increased the peak viscosity to 4014 cP. Freeze-thaw stability was narrowed for both HMT and ANN treated starches compared to the untreated starch. The treatments enhanced water absorption capacity but reduced oil absorption capacity (OAC). The clarity of the modified cassava starch pastes slightly decreased compared to the native starch. Moreover, the whiteness of the treated cassava starch powder was marginally lower than that of the untreated starch, though the differences were not statistically significant. These consequences disclosed that HMT and ANN techniques effectively modified the physicochemical properties of cassava starch
Measurement of the 12C(n,p)12B cross section at n-TOF at CERN by in-beam activation analysis
The integral cross section of the 12C(n,p)12B reaction has been determined for the first time in the neutron energy range from threshold to several GeV at the n-TOF facility at CERN. The measurement relies on the activation technique with the β decay of 12B measured over a period of four half-lives within the same neutron bunch in which the reaction occurs. The results indicate that model predictions, used in a variety of applications, are mostly inadequate. The value of the integral cross section reported here can be used as a benchmark for verifying or tuning model calculations.Peer reviewedFinal Accepted Versio
Effect of invader removal: pollinators stay but some native plants miss their new friend
Removal of invasive species often benefits
biological diversity allowing ecosystems’ recovery.
However, it is important to assess the functional roles
that invaders may have established in their new areas
to avoid unexpected results from species elimination.
Invasive animal-pollinated plants may affect the
plant–pollination interactions by changing pollinator
availability and/or behaviour in the community. Thus,
removal of an invasive plant may have important
effects on pollinator community that may then be
reflected positive or negatively on the reproductive
success of native plants. The objective of this study
was to assess the effect of removing Oxalis pescaprae,
an invasive weed widely spread in the
Mediterranean basin, on plant–pollinator interactions
and on the reproductive success of co-flowering native
plants. For this, a disturbed area in central Portugal,
where this species is highly abundant, was selected.
Visitation rates, natural pollen loads, pollen tube
growth and natural fruit set of native plants were
compared in the presence of O. pes-caprae and after
manual removal of their flowers. Our results showed a
highly resilient pollination network but also revealed
some facilitative effects of O. pes-caprae on the
reproductive success of co-flowering native plants.
Reproductive success of the native plants seems to
depend not only on the number and diversity of floral
visitors, but also on their efficiency as pollinators. The
information provided on the effects of invasive species
on the sexual reproductive success of natives is
essential for adequate management of invaded areas.This work is financed by FEDER funds through the
COMPETE Program and by Portuguese Foundation for Science
and Technology (FCT) funds in the ambit of the project PTDC/
BIA-BIC/110824/2009, by CRUP Acc¸o˜es Integradas Luso-
Espanholas 2010 with the project E10/10, by MCI-Programa de
Internacionalizacio´n de la I ? D (PT2009-0068) and by the
Spanish DGICYT (CGL2009-10466), FEDER funds from the
European Union, and the Xunta de Galicia (INCITE09-
3103009PR). FCT also supported the work of S. Castro (FCT/
BPD/41200/2007) and J. Costa (CB/C05/2009/209; PTDC/
BIA-BIC/110824/2009). The work of V. Ferrero was supported
by the Fundacio´n Ramo´n Areces
Fission Fragment Angular Distribution measurements of 235U and 238U at CERN n-TOF facility
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. EJP Web of Conferences 111, 10002 (2016). DOI: http://dx.doi.org/10.1051/epjconf/201611110002. © 2016 The Authors. Published by EDP Sciences.Neutron-induced fission cross sections of 238U and 235U are used as standards in the fast neutron region up to 200 MeV. A high accuracy of the standards is relevant to experimentally determine other neutron reaction cross sections. Therefore, the detection effciency should be corrected by using the angular distribution of the fission fragments (FFAD), which are barely known above 20 MeV. In addition, the angular distribution of the fragments produced in the fission of highly excited and deformed nuclei is an important observable to investigate the nuclear fission process. In order to measure the FFAD of neutron-induced reactions, a fission detection setup based on parallel-plate avalanche counters (PPACs) has been developed and successfully used at the CERN-n-TOF facility. In this work, we present the preliminary results on the analysis of new 235U(n,f) and 238U(n,f) data in the extended energy range up to 200 MeV compared to the existing experimental data
Medical Therapies for Uterine Fibroids - A Systematic Review and Network Meta-Analysis of Randomised Controlled Trials
BACKGROUND: Uterine fibroids are common, often symptomatic and a third of women need repeated time off work. Consequently 25% to 50% of women with fibroids receive surgical treatment, namely myomectomy or hysterectomy. Hysterectomy is the definitive treatment as fibroids are hormone dependent and frequently recurrent. Medical treatment aims to control symptoms in order to replace or delay surgery. This may improve the outcome of surgery and prevent recurrence. PURPOSE: To determine whether any medical treatment can be recommended in the treatment of women with fibroids about to undergo surgery and in those for whom surgery is not planned based on currently available evidence. STUDY SELECTION: Two authors independently identified randomised controlled trials (RCT) of all pharmacological treatments aimed at the treatment of fibroids from a list of references obtained by formal search of MEDLINE, EMBASE, Cochrane library, Science Citation Index, and ClinicalTrials.gov until December 2013. DATA EXTRACTION: Two authors independently extracted data from identified studies. DATA SYNTHESIS: A Bayesian network meta-analysis was performed following the National Institute for Health and Care Excellence-Decision Support Unit guidelines. Odds ratios, rate ratios, or mean differences with 95% credible intervals (CrI) were calculated. RESULTS AND LIMITATIONS: A total of 75 RCT met the inclusion criteria, 47 of which were included in the network meta-analysis. The overall quality of evidence was very low. The network meta-analysis showed differing results for different outcomes. CONCLUSIONS: There is currently insufficient evidence to recommend any medical treatment in the management of fibroids. Certain treatments have future promise however further, well designed RCTs are needed
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