432 research outputs found
Dosimetric uncertainties related to the elasticity of bladder and rectal walls: Adenocarcinoma of the prostate
Purpose. - Radiotherapy is an important treatment for prostate cancer.During
treatment sessions, bladder and rectal repletion is difficult to quantify and
cannot be measured with a single and initial CT scan acquisition. Some methods,
such as image-guided radiation therapy and dose-guided radiation therapy, aimto
compensate thismissing information through periodic CT acquisitions. The aimis
to adapt patient's position, beam configuration or prescribed dose for a
dosimetric compliance. Methods. -We evaluated organmotion (and repletion) for
54 patients after having computed the original ballistic on a new CT scan
acquisition. A new delineation was done on the prostate, bladder and rectum to
determine the newdisplacements and define organ dosesmistakes (equivalent
uniformdose, average dose and dose-volume histograms). Results. - The new CT
acquisitions confirmed that bladder and rectal volumes were not constant during
sessions. Some cases showed that previously validated treatment plan became
unsuitable. A proposed solution is to correct dosimetries when bladder volume
modifications are significant. The result is an improvement for the stability
of bladder doses, D50 error is reduced by 25.3%, mean dose error by 5.1% and
equivalent uniform dose error by 2.6%. For the rectum this method decreases
errors by only 1%. This process can reduce the risk of mismatch between the
initial scan and following treatment sessions. Conclusion. - For the
proposedmethod, the cone-beamCT is necessary to properly position the isocenter
and to quantify bladder and rectal volume variation and deposited doses. The
dosimetries are performed in the event that bladder (or rectum) volume
modification limits are exceeded. To identify these limits, we have calculated
that a tolerance of 10% for the equivalent uniformdose (compared to the initial
value of the first dosimetry), this represents 11% of obsolete dosimetries for
the bladder, and 4% for the rectum
Tetraspanin CD53 promotes lymphocyte recirculation by stablising L-selectin surface expression
Tetraspanins regulate key processes in immune cells; however, the function of the leukocyterestricted tetraspanin, CD53 has remained unknown. Here we show that CD53 is essential for lymphocyte recirculation. Lymph nodes of Cd53-/- mice were smaller than wild-type mice due to a marked reduction in B cells and a 50% decrease in T cells. This reduced cellularity reflected an inability of Cd53-/- B and T cells to efficiently home to lymph nodes, due to the near absence of L-selectin from Cd53-/- B cells and reduced stability of L-selectin on Cd53-/- T cells. Further analyses, including on human lymphocytes, showed that CD53 inhibits L-selectin shedding via both ADAM17-dependent and -independent mechanisms. The disruption in lymphocyte recirculation in Cd53-/- mice led to impaired immune responses dependent on antigen delivery to lymph nodes. Together these findings demonstrate a previously unrecognized essential role for CD53 in lymphocyte trafficking and immune responses
Objectives, design and main findings until 2020 from the Rotterdam Study
The Rotterdam Study is an ongoing prospective cohort study that started in 1990 in the city of Rotterdam, The Netherlands. The study aims to unravel etiology, preclinical course, natural history and potential targets for intervention for chronic diseases in mid-life and late-life. The study focuses on cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1700 research articles and reports. This article provides an update on the rationale and design of the study. It also presents a summary of the major findings from the preceding 3 years and outlines developments for the coming period
Signaling in Secret: Pay-for-Performance and the Incentive and Sorting Effects of Pay Secrecy
Key Findings: Pay secrecy adversely impacts individual task performance because it weakens the perception that an increase in performance will be accompanied by increase in pay; Pay secrecy is associated with a decrease in employee performance and retention in pay-for-performance systems, which measure performance using relative (i.e., peer-ranked) criteria rather than an absolute scale (see Figure 2 on page 5); High performing employees tend to be most sensitive to negative pay-for- performance perceptions; There are many signals embedded within HR policies and practices, which can influence employeesâ perception of workplace uncertainty/inequity and impact their performance and turnover intentions; and When pay transparency is impractical, organizations may benefit from introducing partial pay openness to mitigate these effects on employee performance and retention
A proposition for the diagnosis and treatment of gastro-oesophageal reflux disease in children: A report from a working group on gastro-oesophageal reflux disease
In this paper, a Working Group on Gastro-Oesophageal Reflux discusses recommendations for the first line diagnostic and therapeutic approach of gastro-oesophageal reflux disease in infants and children. All members of the Working Group agreed that infants with uncomplicated gastro-oesophageal reflux can be safely treated before performing (expensive and often unnecessary) complementary investigations. However, the latter are mandatory if symptoms persist despite appropriate treatment. Oesophageal pH monitoring of long duration (18-24 h) is recommended as the investigation technique of choice in infants and children with atypical presentations of gastro-oesophageal reflux. Upper gastro-intestinal endoscopy in a specialised centre is the technique of choice in infants and children presenting with symptoms suggestive of peptic oesophagitis. Prokinetics, still a relatively new drug family, have already obtained a definitive place in the treatment of gastro-oesophageal reflux disease in infants and children, especially if "non-drug" treatment (positional therapy, dietary recommendations, etc.) was unsuccessful. It was the aim of the Working Group to help the paediatrician with this consensus statement and guide-lines to establish a standardised management of gastro-oesophageal reflux disease in infants and children
Evaluation of a clinical decision rule to guide antibiotic prescription in children with suspected lower respiratory tract infection in The Netherlands
BACKGROUND: Optimising the use of antibiotics is a key component of antibiotic stewardship. Respiratory tract infections (RTIs) are the most common reason for antibiotic prescription in children, even though most of these infections in children under 5 years are viral. This study aims to safely reduce antibiotic prescriptions in children under 5 years with suspected lower RTI at the emergency department (ED), by implementing a clinical decision rule.
METHODS AND FINDINGS: In a stepped-wedge cluster randomised trial, we included children aged 1-60 months presenting with fever and cough or dyspnoea to 8 EDs in The Netherlands. The EDs were of varying sizes, from diverse geographic and demographic regions, and of different hospital types (tertiary versus general). In the pre-intervention phase, children received usual care, according to the Dutch and NICE guidelines for febrile children. During the intervention phase, a validated clinical prediction model (Feverkidstool) including clinical characteristics and C-reactive protein (CRP) was implemented as a decision rule guiding antibiotic prescription. The intervention was that antibiotics were withheld in children with a low or intermediate predicted risk of bacterial pneumonia (â€10%, based on Feverkidstool). Co-primary outcomes were antibiotic prescription rate and strategy failure. Strategy failure was defined as secondary antibiotic prescriptions or hospitalisations, persistence of fever or oxygen dependency up to day 7, or complications. Hospitals were randomly allocated to 1 sequence of treatment each, using computer randomisation. The trial could not be blinded. We used multilevel logistic regression to estimate the effect of the intervention, clustered by hospital and adjusted for time period, age, sex, season, ill appearance, and fever duration; predicted risk was included in exploratory analysis. We included 999 children (61% male, median age 17 months [IQR 9 to 30]) between 1 January 2016 and 30 September 2018: 597 during the pre-intervention phase and 402 during the intervention phase. Most children (77%) were referred by a general practitioner, and half of children were hospitalised. Intention-to-treat analyses showed that overall antibiotic prescription was not reduced (30% to 25%, adjusted odds ratio [aOR] 1.07 [95% CI 0.57 to 2.01, p = 0.75]); strategy failure reduced from 23% to 16% (aOR 0.53 [95% CI 0.32 to 0.88, p = 0.01]). Exploratory analyses showed that the intervention influenced risk groups differently (p < 0.01), resulting in a reduction in antibiotic prescriptions in low/intermediate-risk children (17% to 6%; aOR 0.31 [95% CI 0.12 to 0.81, p = 0.02]) and a non-significant increase in the high-risk group (47% to 59%; aOR 2.28 [95% CI 0.84 to 6.17, p = 0.09]). Two complications occurred during the trial: 1 admission to the intensive care unit during follow-up and 1 pleural empyema at day 10 (both unrelated to the study intervention). Main limitations of the study were missing CRP values in the pre-intervention phase and a prolonged baseline period due to logistical issues, potentially affecting the power o
Quantitative estimate of the paleo-Agulhas leakage
The Indian-Atlantic water exchange south of Africa (Agulhas leakage) is a key component of the global ocean circulation. No quantitative estimation of the paleo-Agulhas leakage exists. We quantify the variability in interocean exchange over the past 640,000âyears, using planktic foraminiferal assemblage data from two marine sediment records to define an Agulhas leakage efficiency index. We confirm the validity of our new approach with a numerical ocean model that realistically simulates the modern Agulhas leakage changes. Our results suggest that, during the past several glacial-interglacial cycles, the Agulhas leakage varied by ~10âsverdrup and more during major climatic transitions. This lends strong credence to the hypothesis that modifications in the leakage played a key role in changing the overturning circulation to full strength mode. Our results are instrumental for validating and quantifying the contribution of the Indian-Atlantic water leakage to the global climate changes
Whole number thinking, learning and development: neuro-cognitive, cognitive and developmental approaches
The participants of working group 2 presented a broad range of studies, 11 papers in total, related to whole number learning representing research groups from 11 countries as follows.
Two large cross-sectional studies focused on developmental aspects of young childrenâs number learning provide a lens for re-examining âtraditionalâ features of number acquisition. van den Heuvel-Panhuizen (the Netherlands) presented a co-authored paper with Elia (Cyprus; Elia and van den Heuvel-Panhuizen 2015) on a cross-cultural study of kindergartnersâ number competence focused on counting, additive and multiplicative thinking. Second, MilinkoviÄ (2015) examined the development of young Serbian childrenâs initial understanding of representations of whole numbers and counting strategies in a large study of 3- to 7-year-olds. Childrenâs invented (formal) representations such as set representation and the number line were found to be limited in their recordings. In a South African study focused on early counting and addition, Roberts (2015) directs attention to the role of teachers by providing a framework to support teachersâ interpretation of young disadvantaged learnersâ representations of number when engaging with whole number additive tasks. Some papers reflected the increasing role of neuroscientific concepts and methodologies utilised in research on WNA learning and development. Sinclair and Coles (2015) drew upon neuroscientific research to highlight the significant role of symbol-to-symbol connections and the use of fingers and touch counting exempli- fied by the TouchCounts iPad app.
Gould (2015) reported aspects of a large Australian large study of children in the first years of schooling aimed at improving numeracy and literacy in disadvantaged communities. A case study exemplified how numerals were identified by relying on a mental number line by using location to retrieve number names. This raised the question addressed in the neuroscientific work of Dehaene and other papers focused on individual differences in how the brain processes numbers.
The Italian PerContare1 project (Baccaglini-Frank 2015) built upon the collaboration between cognitive psychologists and mathematics educators, aimed at developing teaching strategies for preventing and addressing early low achievement in arithmetic. It takes an innovative approach to the development of number sense that is grounded upon a kinaesthetic and visual-spatial approach to part-whole relationships. Mulligan and Woolcott (2015) provided a discussion paper on the underlying nature of number. They presented a broader view of mathematics learning (including WNA) as linked to spatial interaction with the environment; the concept of connectivity across concepts and the development of underlying pattern and structural relationships are central to their approach
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
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