866 research outputs found
Frost and drought: Effects of extreme weather events on stem carbon dynamics in a Mediterranean beech forest
Expression of IL-1 family members upon stimulation with IL-17 differs in keratinocytes derived from psoriasis patients and healthy donors
Low-cost chamber design for simultaneous CO<sub>2</sub> and O<sub>2</sub> flux measurements between tree stems and the atmosphere
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Working time regimes: A panel discussion on continuing problems
This article records a panel discussion at the Organizational Working Time Regimes conference on 31 March 2017 at the University of Graz, Austria. The discussion was moderated by Sara Louise Muhr and the panelists were Jana Costas, Susanne Ekman, Laura Empson and Dan Kärreman. The discussion both departed from yet centred on the concept of time itself: how we understand time as academics, employees and managers, and how the notion of time guides and controls all of us in various ways. Through the different perspectives that the panelists have on time and work regimes, it became evident that time – and discussions of time – is complex and context-dependent and needs to be researched as such. The discussion passionately weaved in and out of key questions on work intensification, inequality regimes and resistance to working time regimes that are deeply entwined with dynamic dialectics such as personal/professional, past/future, individual/organizational, worker/leader, good/bad. The panel in this way takes the reader through difficult discussions about what is ‘extreme’, for whom is it extreme and what interventions (if any) can be made by academics. Doing so, the panelists sensitively drew attention to our own line of work, academia, and the work regimes controlling academics
Bayesian calibration of a soil organic carbon model using Δ<sup>14</sup>C measurements of soil organic carbon and heterotrophic respiration as joint constraints
Soils of temperate forests store significant amounts of organic matter and
are considered to be net sinks of atmospheric CO<sub>2</sub>. Soil organic carbon
(SOC) turnover has been studied using the Δ<sup>14</sup>C values of bulk SOC
or different SOC fractions as observational constraints in SOC models.
Further, the Δ<sup>14</sup>C values of CO<sub>2</sub> that evolved during the
incubation of soil and roots have been widely used together with
Δ<sup>14</sup>C of total soil respiration to partition soil respiration into
heterotrophic respiration (HR) and rhizosphere respiration. However, these
data have not been used as joint observational constraints to determine SOC
turnover times. Thus, we focus on (1) how different combinations of
observational constraints help to narrow estimates of turnover times and
other parameters of a simple two-pool model, the Introductory Carbon Balance
Model (ICBM); (2) whether relaxing the steady-state assumption in a multiple
constraints approach allows the source/sink strength of the soil to be
determined while estimating turnover times at the same time. To this end ICBM
was adapted to model SOC and SO<sup>14</sup>C in parallel with
litterfall and the Δ<sup>14</sup>C of litterfall as driving variables. The
Δ<sup>14</sup>C of the atmosphere with its prominent bomb peak was used as a
proxy for the Δ<sup>14</sup>C of litterfall. Data from three spruce-dominated
temperate forests in Germany and the USA (Coulissenhieb II, Solling D0 and
Howland Tower site) were used to estimate the parameters of ICBM via Bayesian
calibration. Key findings are as follows: (1) the joint use of all four
observational constraints (SOC stock and its Δ<sup>14</sup>C, HR flux and its
Δ<sup>14</sup>C) helped to considerably narrow turnover times of the young
pool (primarily by Δ<sup>14</sup>C of HR) and the old pool (primarily by
Δ<sup>14</sup>C of SOC). Furthermore, the joint use of all observational
constraints made it possible to constrain the humification factor in ICBM,
which describes the fraction of the annual outflux from the young pool that
enters the old pool. The Bayesian parameter estimation yielded the following
turnover times (mean ± standard deviation) for SOC in the young pool:
Coulissenhieb II 1.1 ± 0.5 years, Solling D0 5.7 ± 0.8 years and
Howland Tower 0.8 ± 0.4 years. Turnover times for the old pool were
377 ± 61 years (Coulissenhieb II), 313 ± 66 years (Solling D0)
and 184 ± 42 years (Howland Tower), respectively. (2) At all three
sites the multiple constraints approach was not able to determine if the soil
has been losing or storing carbon. Nevertheless, the relaxed steady-state
assumption hardly introduced any additional uncertainty for the other
parameter estimates. Overall the results suggest that using Δ<sup>14</sup>C
data from more than one carbon pool or flux helps to better constrain SOC
models
Analysis of a global Moreton wave observed on October 28, 2003
We study the well pronounced Moreton wave that occurred in as- sociation with
the X17.2 are/CME event of October 28, 2003. This Moreton wave is striking for
its global propagation and two separate wave centers, which implies that two
waves were launched simultane- ously. The mean velocity of the Moreton wave,
tracked within different sectors of propagation direction, lies in the range of
v ~ 900-1100 km/s with two sectors showing wave deceleration. The perturbation
profile analysis of the wave indicates amplitude growth followed by amplitude
weakening and broadening of the perturbation profile, which is con- sistent
with a disturbance first driven and then evolving into a freely propagating
wave. The EIT wavefront is found to lie on the same kinematical curve as the
Moreton wavefronts indicating that both are different signatures of the same
physical process. Bipolar coronal dim- mings are observed on the same opposite
East-West edges of the active region as the Moreton wave ignition centers. The
radio type II source, which is co-spatially located with the first wave front,
indicates that the wave was launched from an extended source region (& 60 Mm).
These findings suggest that the Moreton wave is initiated by the CME expanding
flanks.Comment: accepted to Ap
Visual acuity and central retinal thickness: fulfilment of retreatment criteria for recurrent neovascular AMD in routine clinical care
Background: To evaluate the fulfilment of retreatment criteria in recurrent neovascular age-related macular degeneration (nAMD) for a pro-re-nata treatment regime with ranibizumab in routine clinical care.
Methods: Data from patients with treatment-naive nAMD were analysed retrospectively. As an `upload', all patients had received three-monthly intravitreal ranibizumab injections in a university eye hospital and were then seen by ophthalmologists in private practice who referred them back in case of recurrence. Recurrence was defined as a decrease of visual acuity (VA) of one line or more (functional retreatment criteria), a central retinal thickness (CRT) increase of at least 100 mm upon Optical Coherence Tomography (OCT) examination (morphological retreatment criteria) or a new macular haemorrhage (clinical retreatment criteria).
Results: We included 92 patients (36 men and 56 women). The mean VA before retreatment of a recurrence was -0.63 +/- 0.33 logMAR and improved significantly (p<0.001) by 0.10 +/- 0.16 logMAR to -0.53 +/- 0.28 logMAR thereafter. Mean CRT before retreatment was 278.07 +/- 87.56 mu m and decreased significantly (p<0.001) by 71.22 +/- 106.93 to 206.85 +/- 60.30 mu m. Evaluation of the fulfilment of retreatment criteria revealed functional retreatment criteria in 82.6% of patients. However, upon re-evaluation of VA using Early Treatment Diabetic Retinopathy Study (ETDRS) charts in the treatment centre, mean decrease of VA was 10 letters as compared with the end of upload therapy. All patients presented an increased CRT when treated for recurrence of nAMD (mean increase 69.47 mu m), but the morphological retreatment criteria (CRT increase of 100 mu m or more) were fulfilled in only 44.4% of patients upon Spectral Domain OCT (SD-OCT) evaluation in the treatment centre.
Conclusions: In a routine clinical care, evaluation of VA using ETDRS charts seems to be more sensitive than Snellen VA testing. Quantitative OCT-based retreatment criteria (eg, increase of CRT of 100 mm or more) appear to be not sensitive enough in a clinical setting with referring ophthalmologists
Photosensitiser functionalised luminescent upconverting nanoparticles for efficient photodynamic therapy of breast cancer cells
Photodynamic therapy (PDT) is a well-established treatment of cancer in which cell toxic reactive oxygen species, including singlet oxygen (1O2), are produced by a photosensitiser drug following irradiation of a specific wavelength. Visible light is commonly used as the excitation source in PDT, although these wavelengths do have limited tissue penetration. In this research, upconverting nanoparticles (UCNPs) functionalised with the photosensitiser Rose Bengal (RB) have been designed and synthesised for PDT of breast cancer cells. The use of UCNPs shifts the required excitation wavelength for the production of 1O2 to near infrared light (NIR) thus allowing deeper tissue penetration. The system was designed to maximise the production of 1O2via efficient Förster resonance energy transfer (FRET) from the UCNPs to the photosensitiser. Highly luminescent NaYF4:Yb,Er,Gd@NaYF4 core–shell UCNPs were synthesised that exhibited two main anti-Stokes emission bands at 541 and 652 nm following 980 nm irradiation. RB was chosen as the photosensitiser since its absorption band overlaps with the green emission of the UCNPs. To achieve efficient energy transfer from the nanoparticles to the photosensitiser, the functionalised UCNPs included a short L-lysine linker to attach the RB to the nanocore yielding RB-lysine functionalised UCNPs. The efficient FRET from the UCNPs to the RB was confirmed by luminescence lifetime measurements. The light emitted by the UCNPs at 541 nm, following excitation at 980 nm, generates the 1O2via the RB. Multi-photon and confocal laser scanning microscopies confirmed the internalisation of the RB-lysine-UCNPs by SK-BR-3 breast cancer cells. Cell viability studies revealed that the RB-lysine-UCNPs induced low dark toxicity in cells prior to PDT treatment. Importantly, following irradiation at 980 nm, high levels of cell death were observed in cells loaded with the RB-lysine-UCNPs. Cell death following PDT treatment was also confirmed using propidium iodide and confocal microscopy. The high drug loading capacity (160 RB/nanoparticle) of the UCNPs, the efficient FRET from the UCNPs to the photosensitiser, the high level of accumulation inside the cells and their PDT cell kill suggest that the RB-lysine-UCNPs are promising for NIR PDT and hence suitable for the treatment of deep-lying cancer tumours
Visual acuity and central retinal thickness: fulfilment of retreatment criteria for recurrent neovascular AMD in routine clinical care
Background: To evaluate the fulfilment of retreatment criteria in recurrent neovascular age-related macular degeneration (nAMD) for a pro-re-nata treatment regime with ranibizumab in routine clinical care.
Methods: Data from patients with treatment-naive nAMD were analysed retrospectively. As an `upload', all patients had received three-monthly intravitreal ranibizumab injections in a university eye hospital and were then seen by ophthalmologists in private practice who referred them back in case of recurrence. Recurrence was defined as a decrease of visual acuity (VA) of one line or more (functional retreatment criteria), a central retinal thickness (CRT) increase of at least 100 mm upon Optical Coherence Tomography (OCT) examination (morphological retreatment criteria) or a new macular haemorrhage (clinical retreatment criteria).
Results: We included 92 patients (36 men and 56 women). The mean VA before retreatment of a recurrence was -0.63 +/- 0.33 logMAR and improved significantly (p<0.001) by 0.10 +/- 0.16 logMAR to -0.53 +/- 0.28 logMAR thereafter. Mean CRT before retreatment was 278.07 +/- 87.56 mu m and decreased significantly (p<0.001) by 71.22 +/- 106.93 to 206.85 +/- 60.30 mu m. Evaluation of the fulfilment of retreatment criteria revealed functional retreatment criteria in 82.6% of patients. However, upon re-evaluation of VA using Early Treatment Diabetic Retinopathy Study (ETDRS) charts in the treatment centre, mean decrease of VA was 10 letters as compared with the end of upload therapy. All patients presented an increased CRT when treated for recurrence of nAMD (mean increase 69.47 mu m), but the morphological retreatment criteria (CRT increase of 100 mu m or more) were fulfilled in only 44.4% of patients upon Spectral Domain OCT (SD-OCT) evaluation in the treatment centre.
Conclusions: In a routine clinical care, evaluation of VA using ETDRS charts seems to be more sensitive than Snellen VA testing. Quantitative OCT-based retreatment criteria (eg, increase of CRT of 100 mm or more) appear to be not sensitive enough in a clinical setting with referring ophthalmologists
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