126 research outputs found
Forecasts and assimilation experiments of the Antarctic ozone hole 2008
The 2008 Antarctic ozone hole was one of the largest and most long-lived in
recent years. Predictions of the ozone hole were made in near-real time
(NRT) and hindcast mode with the Integrated Forecast System (IFS) of the
European Centre for Medium-Range Weather Forecasts (ECMWF). The forecasts
were carried out both with and without assimilation of satellite
observations from multiple instruments to provide more realistic initial
conditions. Three different chemistry schemes were applied for the
description of stratospheric ozone chemistry: (i) a linearization of the
ozone chemistry, (ii) the stratospheric chemical mechanism of the Model of
Ozone and Related Chemical Tracers, version 3, (MOZART-3) and (iii) the
relaxation to climatology as implemented in the Transport Model, version 5,
(TM5). The IFS uses the latter two schemes by means of a two-way coupled
system. Without assimilation, the forecasts showed model-specific
shortcomings in predicting start time, extent and duration of the ozone
hole. The assimilation of satellite observations from the Microwave Limb
Sounder (MLS), the Ozone Monitoring Instrument (OMI), the Solar
Backscattering Ultraviolet radiometer (SBUV-2) and the SCanning Imaging
Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) led to a
significant improvement of the forecasts when compared with total columns
and vertical profiles from ozone sondes. The combined assimilation of
observations from multiple instruments helped to overcome limitations of the
ultraviolet (UV) sensors at low solar elevation over Antarctica. The
assimilation of data from MLS was crucial to obtain a good agreement with
the observed ozone profiles both in the polar stratosphere and troposphere.
The ozone analyses by the three model configurations were very similar
despite the different underlying chemistry schemes. Using ozone analyses as
initial conditions had a very beneficial but variable effect on the
predictability of the ozone hole over 15 days. The initialized forecasts
with the MOZART-3 chemistry produced the best predictions of the increasing
ozone hole whereas the linear scheme showed the best results during the
ozonehole closure
Are older adults with chronic musculoskeletal pain less active than older adults without pain? A systematic review and meta-analysis.
Objective:
To compare the overall levels of physical activity of older adults with chronic musculoskeletal pain and asymptomatic controls.
Review Methods:
A systematic review of the literature was conducted using a Cochrane methodology and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Major electronic databases were searched from inception until December 2012, including the Cochrane Library, CINAHL, EBSCO, EMBASE, Medline, PubMed, PsycINFO, and the international prospective register of systematic reviews. In addition, citation chasing was undertaken, and key authors were contacted. Eligibility criteria were established around participants used and outcome measures focusing on daily physical activity. A meta-analysis was conducted on appropriate studies.
Results:
Eight studies met the eligibility criteria, four of these reported a statistically lower level of physical activity in the older adult sampl e with chronic pain compared with the asymptomatic group. It was possible to perform a non-heterogeneous meta-analysis on five studies. This established that 1,159 older adults with chronic pain had a significantly lower level of physical activity (â0.20, confidence interval 95%â=ââ0.34 to â0.06, pâ=â0.004) compared with 576 without chronic pain.
Conclusion:
Older adults with chronic pain appear to be less active than asymptomatic controls. Although this difference was small, it is likely to be clinically meaningful. It is imperative that clinicians encourage older people with chronic pain to remain active as physical activity is a central non-pharmacological strategy in the management of chronic pain and is integral for healthy aging. Future research should prioritize the use of objective measurement of physical activity
Global model simulations of air pollution during the 2003 European heat wave
Three global Chemistry Transport Models - MOZART, MOCAGE, and TM5 - as well as MOZART coupled to the IFS meteorological model including assimilation of ozone (O-3) and carbon monoxide (CO) satellite column retrievals, have been compared to surface measurements and MOZAIC vertical profiles in the troposphere over Western/Central Europe for summer 2003. The models reproduce the meteorological features and enhancement of pollution during the period 2-14 August, but not fully the ozone and CO mixing ratios measured during that episode. Modified normalised mean biases are around -25% (except similar to 5% for MOCAGE) in the case of ozone and from -80% to -30% for CO in the boundary layer above Frankfurt. The coupling and assimilation of CO columns from MOPITT overcomes some of the deficiencies in the treatment of transport, chemistry and emissions in MOZART, reducing the negative biases to around 20%. The high reactivity and small dry deposition velocities in MOCAGE seem to be responsible for the overestimation of O-3 in this model. Results from sensitivity simulations indicate that an increase of the horizontal resolution to around 1 degrees x1 degrees and potential uncertainties in European anthropogenic emissions or in long-range transport of pollution cannot completely account for the underestimation of CO and O-3 found for most models. A process-oriented TM5 sensitivity simulation where soil wetness was reduced results in a decrease in dry deposition fluxes and a subsequent ozone increase larger than the ozone changes due to the previous sensitivity runs. However this latest simulation still underestimates ozone during the heat wave and overestimates it outside that period. Most probably, a combination of the mentioned factors together with underrepresented biogenic emissions in the models, uncertainties in the modelling of vertical/horizontal transport processes in the proximity of the boundary layer as well as limitations of the chemistry schemes are responsible for the underestimation of ozone (overestimation in the case of MOCAGE) and CO found in the models during this extreme pollution event
Global model simulations of air pollution during the 2003 European heat wave
Three global Chemistry Transport Models â MOZART, MOCAGE, and TM5 â as well as MOZART coupled to the IFS meteorological model including assimilation of ozone (O<sub>3</sub>) and carbon monoxide (CO) satellite column retrievals, have been compared to surface measurements and MOZAIC vertical profiles in the troposphere over Western/Central Europe for summer 2003. The models reproduce the meteorological features and enhancement of pollution during the period 2â14 August, but not fully the ozone and CO mixing ratios measured during that episode. Modified normalised mean biases are around &minus;25% (except ~5% for MOCAGE) in the case of ozone and from &minus;80% to &minus;30% for CO in the boundary layer above Frankfurt. The coupling and assimilation of CO columns from MOPITT overcomes some of the deficiencies in the treatment of transport, chemistry and emissions in MOZART, reducing the negative biases to around 20%. The high reactivity and small dry deposition velocities in MOCAGE seem to be responsible for the overestimation of O<sub>3</sub> in this model. Results from sensitivity simulations indicate that an increase of the horizontal resolution to around 1&deg;&times;1&deg; and potential uncertainties in European anthropogenic emissions or in long-range transport of pollution cannot completely account for the underestimation of CO and O<sub>3</sub> found for most models. A process-oriented TM5 sensitivity simulation where soil wetness was reduced results in a decrease in dry deposition fluxes and a subsequent ozone increase larger than the ozone changes due to the previous sensitivity runs. However this latest simulation still underestimates ozone during the heat wave and overestimates it outside that period. Most probably, a combination of the mentioned factors together with underrepresented biogenic emissions in the models, uncertainties in the modelling of vertical/horizontal transport processes in the proximity of the boundary layer as well as limitations of the chemistry schemes are responsible for the underestimation of ozone (overestimation in the case of MOCAGE) and CO found in the models during this extreme pollution event
Robot tutors:Welcome or ethically questionable?
Robot tutors provide new opportunities for education. However, they also introduce moral challenges. This study reports a systematic literature re-view (N = 256) aimed at identifying the moral considerations related to ro-bots in education. While our findings suggest that robot tutors hold great potential for improving education, there are multiple values of both (special needs) children and teachers that are impacted (positively and negatively) by its introduction. Positive values related to robot tutors are: psychological welfare and happiness, efficiency, freedom from bias and usability. However, there are also concerns that robot tutors may negatively impact these same values. Other concerns relate to the values of friendship and attachment, human contact, deception and trust, privacy, security, safety and accountability. All these values relate to children and teachers. The moral values of other stakeholder groups, such as parents, are overlooked in the existing literature. The results suggest that, while there is a potential for ap-plying robot tutors in a morally justified way, there are imported stake-holder groups that need to be consulted to also take their moral values into consideration by implementing tutor robots in an educational setting. (from Narcis.nl
Einstein's quantum theory of the monatomic ideal gas: non-statistical arguments for a new statistics
In this article, we analyze the third of three papers, in which Einstein
presented his quantum theory of the ideal gas of 1924-1925. Although it failed
to attract the attention of Einstein's contemporaries and although also today
very few commentators refer to it, we argue for its significance in the context
of Einstein's quantum researches. It contains an attempt to extend and exhaust
the characterization of the monatomic ideal gas without appealing to
combinatorics. Its ambiguities illustrate Einstein's confusion with his initial
success in extending Bose's results and in realizing the consequences of what
later became to be called Bose-Einstein statistics. We discuss Einstein's
motivation for writing a non-combinatorial paper, partly in response to
criticism by his friend Ehrenfest, and we paraphrase its content. Its arguments
are based on Einstein's belief in the complete analogy between the
thermodynamics of light quanta and of material particles and invoke
considerations of adiabatic transformations as well as of dimensional analysis.
These techniques were well-known to Einstein from earlier work on Wien's
displacement law, Planck's radiation theory, and the specific heat of solids.
We also investigate the possible role of Ehrenfest in the gestation of the
theory.Comment: 57 pp
Rapid, high sensitivity, point-of-care test for cardiac troponin based on optomagnetic biosensor
Abstract BACKGROUND: We present a prototype handheld device based on a newly develope
Role of regional wetland emissions in atmospheric methane variability
Atmospheric methane (CH4) accounts for ~20% of the total direct anthropogenic radiative forcing by long-lived greenhouse gases. Surface observations show a pause (1999-2006) followed by a resumption in CH4 growth, which remain largely unexplained. Using a land surface model, we estimate wetland CH4 emissions from 1993 to 2014 and study the regional contributions to changes in atmospheric CH4. Atmospheric model simulations using these emissions, together with other sources, compare well with surface and satellite CH4 data. Modelled global wetland emissions vary by ±3%/yr (Ï=4.8 Tg), mainly due to precipitation-induced changes in wetland area, but the integrated effect makes only a small contribution to the pause in CH4 growth from 1999 to 2006. Increasing temperature, which increases wetland area, drives a long-term trend in wetland CH4 emissions of +0.2%/yr (1999 to 2014). The increased growth post-2006 was partly caused by increased wetland emissions (+3%), mainly from Tropical Asia, Sourthern Africa and Australia
The added value of C-reactive protein to clinical signs and symptoms in patients with obstructive airway disease: results of a diagnostic study in primary care
BACKGROUND: To evaluate the diagnostic accuracy of clinical signs and symptoms, C-reactive protein (CRP) and spirometric parameters and determine their interrelation in patients suspected to have an obstructive airway disease (OAD) in primary care. METHODS: In a cross sectional diagnostic study, 60 adult patients coming to the general practitioner (GP) for the first-time with complaints suspicious for obstructive airway disease (OAD) underwent spirometry. Peak expiratory flow (PEF)-variability within two weeks was determined in patients with inconspicuous spirometry. Structured medical histories were documented and CRP was measured. The reference standard was the Tiffeneau ratio (FEV(1)/VC) in spirometry and the PEF-variability. OAD was diagnosed when FEV(1)/VC †70% or PEF-variability > 20%. RESULTS: 37 (62%) patients had OAD. The best cut-off value for CRP was found at 2 mg/l with a diagnostic odds ratio (OR) of 4.4 (95% CI 1.4â13.8). Self-reported wheezing was significantly related with OAD (OR 3.4; CI 1.1â10.3), whereas coughing was inversely related (OR 0.2; CI 0.1â0.7). The diagnostic OR of CRP increased when combined with dyspnea (OR 8.5; 95% CI 1.7â42.3) or smoking history (OR 8.4; 95% CI 1.5â48.9). CRP (p = 0.004), FEV(1 )(p = 0.001) and FIV(1 )(p = 0.023) were related with the severity of dyspnea. CRP increased with the number of cigarettes, expressed in pack years (p = 0.001). CONCLUSION: The diagnostic accuracy of clinical signs and symptoms was low. The diagnostic accuracy of CRP improved in combination with dyspnea and smoking history. Due to their coherence with the severity of dyspnea and number of cigarettes respectively, CRP and spirometry might allow risk stratification of patients with OAD in primary care. Further studies need to be done to confirm these findings
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