The kinetics of the reactions of PO with O2 and PO2 with O3 were studied at temperatures ranging from ∼190 to 340 K, using a pulsed laser photolysis-laser induced fluorescence technique. For the ...reaction of PO + O2, there is evidence of both a two- and three-body exit channel, producing PO2 + O and PO3, respectively. Potential energy surfaces of both the PO + O2 and PO2 + O3 systems were calculated using electronic structure theory and combined with RRKM calculations to explain the observed pressure and temperature dependences. For PO + O2, at pressures typical of a planetary upper atmosphere where meteoric ablation of P will occur, the reaction is effectively pressure independent with a yield of PO2 + O of >99%; the rate coefficient can be expressed by log10(k, 120–500 K, cm3 molecule–1 s–1) = −13.915 + 2.470 log10(T) – 0.5020(log10(T))2, with an uncertainty of ±10% over the experimental temperature range (191–339 K). With increasing pressure, the yield of PO3 increases, reaching ∼90% at a pressure of 1 atm and T = 300 K. For PO2 + O3, k(188–339 K) = 3.7 × 10–11 exp(−1131/T) cm3 molecule–1 s–1, with an uncertainty of ±26% over the stated temperature range. Laser-induced fluorescence spectra of PO over the wavelength range 245–248 nm were collected and simulated using pgopher to obtain new spectroscopic constants for the ground and v = 1 vibrational levels of the X 2Π and A 2Σ+ states of PO.
Summary Background Minocycline has anti-apoptotic and anti-inflammatory effects in vitro, and extends survival in mouse models of some neurological conditions. Several trials are planned or are in ...progress to assess whether minocycline slows human neurodegeneration. We aimed to test the efficacy of minocycline as a treatment for amyotrophic lateral sclerosis (ALS). Methods We did a multicentre, randomised placebo-controlled phase III trial. After a 4-month lead-in phase, 412 patients were randomly assigned to receive placebo or minocycline in escalating doses of up to 400 mg/day for 9 months. The primary outcome measure was the difference in rate of change in the revised ALS functional rating scale (ALSFRS-R). Secondary outcome measures were forced vital capacity (FVC), manual muscle testing (MMT), quality of life, survival, and safety. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov , number NCT00047723. Findings ALSFRS-R score deterioration was faster in the minocycline group than in the placebo group (−1·30 vs −1·04 units/month, 95% CI for difference −0·44 to −0·08; p=0·005). Patients on minocycline also had non-significant tendencies towards faster decline in FVC (−3·48 vs −3·01, −1·03 to 0·11; p=0·11) and MMT score (−0·30 vs −0·26, −0·08 to 0·01; p=0·11), and greater mortality during the 9-month treatment phase (hazard ratio=1·32, 95% CI 0·83 to 2·10; p=0·23) than did patients on placebo. Quality-of-life scores did not differ between the treatment groups. Non-serious gastrointestinal and neurological adverse events were more common in the minocycline group than in the placebo group, but these events were not significantly related to the decline in ALSFRS-R score. Interpretation Our finding that minocycline has a harmful effect on patients with ALS has implications for trials of minocycline in patients with other neurological disorders, and for how potential neuroprotective agents are screened for use in patients with ALS.
Airglow is a well-known phenomenon in the Earth’s upper atmosphere, which arises from the emissions of energetic atoms and molecules. The Meinel band emission from high vibrationally excited OH(X) ...radicals is one of the more important contributors to the airglow from the mesosphere/lower thermosphere. The H + O3 reaction has long been regarded as the dominant source of these OH(X, high v) radicals. Here we demonstrate that vacuum ultraviolet (VUV) photolysis of water vapor at λ ∼ 112.8 nm represents another source of exceptionally highly vibrationally excited OH(X) radicals, with a nascent vibrational state population distribution that maximizes at v = 9 and extends to at least the v = 15 level. Atmospheric chemistry modeling indicates that OH(X, high v) radicals from H2O photolysis might be detectable in the OH Meinel band dayglow in the upper atmosphere of Earth and should dominate the corresponding emission from the Martian atmosphere. VUV photolysis of H2O also produces electronically excited OH(A) radicals, and simultaneous detection of emissions from OH(X, high v) and OH(A) is shown to offer a route to identifying high-oxygen exoplanetary atmospheres.
Population-based evidence on second cancer risk following autologous haematopoietic SCT (HCT) is lacking. We quantified second cancer risk for a national, population-based cohort of adult Australians ...receiving autologous HCT for cancer and notified to the Australasian Bone Marrow Transplant Recipient Registry 1992-2007 (n=7765). Cancer diagnoses and deaths were ascertained by linkage with the Australian Cancer Database and National Death Index. Standardized incidence ratios (SIRs) were calculated and Cox regression models were used to estimate within-cohort risk factors treating death as a competing risk. During a median 2.5 years follow-up, second cancer risk was modestly increased compared with the general population (SIR 1.4, 95% confidence interval 1.2-1.6); significantly elevated risk was also observed for AML/myelodysplastic syndrome (SIR=20.6), melanoma (SIR=2.6) and non-Hodgkin lymphoma (SIR=3.3). Recipients at elevated risk of any second cancer included males, and those transplanted at a younger age, in an earlier HCT era, or for lymphoma or testicular cancer. Male sex, older age (>45 years) and history of relapse after HCT predicted melanoma risk. Transplantation for Hodgkin lymphoma and older age were associated with lung cancer risk. Second malignancies are an important late effect and these results inform and emphasize the need for cancer surveillance in autologous HCT survivors.
•The study assesses the impact of using year-to-year variable monthly LAI to calibrate VIC model and its performance.•VIC model efficiency can be improved by using year-to-year variable monthly LAI ...to calibrate the model.•Leaf area index elasticity of runoff is strongly related to catchment characteristics.•Uses of long-term mean monthly LAI in VIC model tend to underestimate simulate runoff in dry period and overestimate in wet period.
This study assessed the effect of using observed monthly leaf area index (LAI) on hydrological model performance and the simulation of runoff using the Variable Infiltration Capacity (VIC) hydrological model in the Goulburn–Broken catchment of Australia, which has heterogeneous vegetation, soil and climate zones. VIC was calibrated with both observed monthly LAI and long-term mean monthly LAI, which were derived from the Global Land Surface Satellite (GLASS) leaf area index dataset covering the period from 1982 to 2012. The model performance under wet and dry climates for the two different LAI inputs was assessed using three criteria, the classical Nash–Sutcliffe efficiency, the logarithm transformed flow Nash–Sutcliffe efficiency and the percentage bias. Finally, the deviation of the simulated monthly runoff using the observed monthly LAI from simulated runoff using long-term mean monthly LAI was computed. The VIC model predicted monthly runoff in the selected sub-catchments with model efficiencies ranging from 61.5% to 95.9% during calibration (1982–1997) and 59% to 92.4% during validation (1998–2012). Our results suggest systematic improvements, from 4% to 25% in Nash–Sutcliffe efficiency, in sparsely forested sub-catchments when the VIC model was calibrated with observed monthly LAI instead of long-term mean monthly LAI. There was limited systematic improvement in tree dominated sub-catchments. The results also suggest that the model overestimation or underestimation of runoff during wet and dry periods can be reduced to 25 mm and 35 mm respectively by including the year-to-year variability of LAI in the model, thus reflecting the responses of vegetation to fluctuations in climate and other factors. Hence, the year-to-year variability in LAI should not be neglected; rather it should be included in model calibration as well as simulation of monthly water balance.
Rate coefficients for the CH3 + CH3 reaction, over the temperature range 300–900 K, have been corrected for errors in the absorption coefficients used in the original publication ( Slagle et al., J. ...Phys. Chem. 1988, 92, 2455−2462 ). These corrections necessitated the development of a detailed model of the B̃2A1′ (3s)–X̃2A2″ transition in CH3 and its validation against both low temperature and high temperature experimental absorption cross sections. A master equation (ME) model was developed, using a local linearization of the second-order decay, which allows the use of standard matrix diagonalization methods for the determination of the rate coefficients for CH3 + CH3. The ME model utilized inverse Laplace transformation to link the microcanonical rate constants for dissociation of C2H6 to the limiting high pressure rate coefficient for association, k ∞(T); it was used to fit the experimental rate coefficients using the Levenberg–Marquardt algorithm to minimize χ2 calculated from the differences between experimental and calculated rate coefficients. Parameters for both k ∞(T) and for energy transfer ⟨ΔE⟩down(T) were varied and optimized in the fitting procedure. A wide range of experimental data were fitted, covering the temperature range 300–2000 K. A high pressure limit of k ∞(T) = 5.76 × 10–11(T/298 K)−0.34 cm3 molecule–1 s–1 was obtained, which agrees well with the best available theoretical expression.
Anthropogenic climate change is projected to enrich the atmosphere with carbon dioxide, change vegetation dynamics and influence the availability of water at the catchment scale. This study combines ...a nonlinear model for estimating changes in leaf area index (LAI) due to climatic fluctuations with the variable infiltration capacity (VIC) hydrological model to improve catchment streamflow prediction under a changing climate. The combined model was applied to 13 gauged sub-catchments with different land cover types (crop, pasture and tree) in the Goulburn–Broken catchment, Australia, for the "Millennium Drought" (1997–2009) relative to the period 1983–1995, and for two future periods (2021–2050 and 2071–2100) and two emission scenarios (Representative Concentration Pathway (RCP) 4.5 and RCP8.5) which were compared with the baseline historical period of 1981–2010. This region was projected to be warmer and mostly drier in the future as predicted by 38 Coupled Model Intercomparison Project Phase 5 (CMIP5) runs from 15 global climate models (GCMs) and for two emission scenarios. The results showed that during the Millennium Drought there was about a 29.7–66.3 % reduction in mean annual runoff due to reduced precipitation and increased temperature. When drought-induced changes in LAI were included, smaller reductions in mean annual runoff of between 29.3 and 61.4 % were predicted. The proportional increase in runoff due to modeling LAI was 1.3–10.2 % relative to not including LAI. For projected climate change under the RCP4.5 emission scenario, ignoring the LAI response to changing climate could lead to a further reduction in mean annual runoff of between 2.3 and 27.7 % in the near-term (2021–2050) and 2.3 to 23.1 % later in the century (2071–2100) relative to modeling the dynamic response of LAI to precipitation and temperature changes. Similar results (near-term 2.5–25.9 % and end of century 2.6–24.2 %) were found for climate change under the RCP8.5 emission scenario. Incorporating climate-induced changes in LAI in the VIC model reduced the projected declines in streamflow and confirms the importance of including the effects of changes in LAI in future projections of streamflow.
Photodissociation of vibrationally and electronically excited sulfur dimer molecules (S2) has been studied in a combined experimental and computational quantum chemistry study in order to ...characterize bound-continuum transitions. Ab initio quantum chemistry calculations are carried out to predict the potential energy curves, spin–orbit coupling, transition moments, and bound-continuum spectra of S2 for comparison with the experimental data. The experiment uses velocity map imaging to measure S-atom production following S2 photoexcitation in the ultraviolet region (320–205 nm). A pulsed electric discharge in H2S produces ground-state S2 X3Σg –(v = 0–15) as well as electronically excited singlet sulfur and b1Σg +(v = 0, 1), and evidence is presented for the production and photodissociation of S2 a1Δg. In a previous paper, we reported threshold photodissociation of S2X3Σg –(v = 0) in the 282–266 nm region. In the present study, S(3P J ) fine structure branching and angular distributions for photodissociation of S2 (X3Σg –(v = 0), a1Δg and b1Σg +) via the B″3Πu, B3Σu – and 11Πu excited states are reported. In addition, photodissociation of the X3Σg –(v = 0) state of S2 to the second dissociation limit producing S(3P2) + S(1D) is characterized. The present results on S2 photodynamics are compared to those of the well-studied electronically isovalent O2 molecule.
Updated analyses of several singlet Rydberg states of O
2
via spectra involving excitation from the metastable a
1
Δ
g
and
states are presented. The high-quality FT-VUV spectra available from the ...DESIRS beamline at the SOLEIL synchrotron gives significantly improved spectra compared to previous work. The Rydberg states analysed include
v = 0-4, 3pσ
1
Π
u
v = 0-2, 3pπ
1
Δ
u
v = 0-2,
v = 0-1, 4pσ
1
Π
u
v = 0 and 4pπ
1
Δ
u
v = 0. This is complemented by high-quality ab initio calculations on the
and
1
Δ
u
Rydberg states to determine the transition moments providing the first quantitative cross-sections for Rydberg -
transitions. These are validated against the experimental data. The results suggest the most promising candidate for determining
number density is likely to be the 1-0 band of the
transition at 131.3 nm.
Crohn's disease (CD) is a heterogeneous disorder characterized by diverse clinical phenotypes. Childhood-onset CD has been described as a more aggressive phenotype. Genetic and immune factors may ...influence disease phenotype and clinical course. We examined the association of immune responses to microbial antigens with disease behavior and prospectively determined the influence of immune reactivity on disease progression in pediatric CD patients.
Sera were collected from 196 pediatric CD cases and tested for immune responses: anti-I2, anti-outer membrane protein C (anti-OmpC), anti-CBir1 flagellin (anti-CBir1), and anti-Saccharomyces-cerevisiae (ASCA) using ELISA. Associations between immune responses and clinical phenotype were evaluated.
Fifty-eight patients (28%) developed internal penetrating and/or stricturing (IP/S) disease after a median follow-up of 18 months. Both anti-OmpC (p < 0.0006) and anti-I2 (p < 0.003) were associated with IP/S disease. The frequency of IP/S disease increased with increasing number of immune responses (p trend = 0.002). The odds of developing IP/S disease were highest in patients positive for all four immune responses (OR (95% CI): 11 (1.5-80.4); p = 0.03). Pediatric CD patients positive for > or =1 immune response progressed to IP/S disease sooner after diagnosis as compared to those negative for all immune responses (p < 0.03).
The presence and magnitude of immune responses to microbial antigens are significantly associated with more aggressive disease phenotypes among children with CD. This is the first study to prospectively demonstrate that the time to develop a disease complication in children is significantly faster in the presence of immune reactivity, thereby predicting disease progression to more aggressive disease phenotypes among pediatric CD patients.
PDF
