Convective cloud systems in the maritime tropics play a critical role in
global climate, but accurately representing aerosol interactions within
these clouds persists as a major challenge for weather ...and climate
modelling. We quantify the effect of ice-nucleating particles (INPs) on the
radiative properties of a complex tropical Atlantic deep convective cloud
field using a regional model with an advanced double-moment microphysics
scheme. Our results show that the domain-mean daylight outgoing radiation
varies by up to 18 W m−2 depending on the chosen INP parameterisation.
The key distinction between different INP parameterisations is the
temperature dependence of ice formation, which alters the vertical
distribution of cloud microphysical processes. The controlling effect of the
INP temperature dependence is substantial even in the presence of
Hallett–Mossop secondary ice production, and the effects of secondary ice
formation depend strongly on the chosen INP parameterisation. Our results
have implications for climate model simulations of tropical clouds and
radiation, which currently do not consider a link between INP particle type
and ice water content. The results also provide a challenge to the INP
measurement community, as we demonstrate that INP concentration
measurements are required over the full mixed-phase temperature regime,
which covers around 10 orders of magnitude.
Ice crystal formation in the mixed-phase region of deep convective clouds can affect the properties of climatically important convectively generated anvil clouds. Small ice crystals in the ...mixed-phase cloud region can be formed by heterogeneous ice nucleation by ice-nucleating particles (INPs) and secondary ice production (SIP) by, for example, the Hallett-Mossop process. We quantify the effects of INP number concentration, the temperature dependence of the INP number concentration at mixed-phase temperatures, and the Hallett-Mossop splinter production efficiency on the anvil of an idealised deep convective cloud using a Latin hypercube sampling method, which allows optimal coverage of a multidimensional parameter space, and statistical emulation, which allows us to identify interdependencies between the three uncertain inputs.
The MiniBooNE Collaboration observes unexplained electronlike events in the reconstructed neutrino energy range from 200 to 475 MeV. With 6.46x10;{20} protons on target, 544 electronlike events are ...observed in this energy range, compared to an expectation of 415.2+/-43.4 events, corresponding to an excess of 128.8+/-20.4+/-38.3 events. The shape of the excess in several kinematic variables is consistent with being due to either nu_{e} and nuover _{e} charged-current scattering or nu_{mu} neutral-current scattering with a photon in the final state. No significant excess of events is observed in the reconstructed neutrino energy range from 475 to 1250 MeV, where 408 events are observed compared to an expectation of 385.9+/-35.7 events.
The observation of neutrino oscillations is clear evidence for physics beyond the standard model. To make precise measurements of this phenomenon, neutrino oscillation experiments, including ...MiniBooNE, require an accurate description of neutrino charged current quasielastic (CCQE) cross sections to predict signal samples. Using a high-statistics sample of nu_(mu) CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events observed in a carbon-based detector. The extracted parameters include an effective axial mass, M_(A)(eff)=1.23+/-0.20 GeV, that describes the four-momentum dependence of the axial-vector form factor of the nucleon, and a Pauli-suppression parameter, kappa=1.019+/-0.011. Such a modified Fermi gas model may also be used by future accelerator-based experiments measuring neutrino oscillations on nuclear targets.
OBJECTIVES
This study was conducted to assess whether myocardial ischemia and/or infarction are involved in the pathogenesis of late right ventricular dysfunction in adult survivors of atrial baffle ...repair for transposition of the great arteries in infancy.
BACKGROUND
The medium-term success of intraatrial baffle repair for transposition of the great arteries is good, with many patients surviving into adult life, but prognosis can be limited by progressive right ventricular dysfunction. We hypothesized that ongoing myocardial ischemia and/or infarction are important factors in the pathogenesis of this complication. Radionuclide techniques offer an opportunity to study both myocardial perfusion and concomitant ventricular wall motion.
METHODS
Dipyridamole sestamibi single-photon emission computed tomography followed by rest sestamibi single-photon emission computed tomography was used to assess right ventricular myocardial perfusion, wall motion, wall thickening and ejection fraction in 22 adolescents/young adults who had undergone atrial baffle repair for simple transposition of the great arteries at median 6.7 (range 0.5 to 54) months of age. The patients were aged 10 to 25 (median 15.5) years; 19 in New York Heart Association class I, 2 in class II and 1 in class III. All were in a regular cardiac rhythm during the studies. The right ventricular tomographic images were examined in three parallel and two orthogonal planes, analyzed in 12 segments.
RESULTS
Perfusion defects were evident in all patients in at least one segment, in either the rest or stress images. Twelve patients (55%) demonstrated fixed defects only, nine (41%) had fixed and reversible defects and one (4.5%) had reversible defects only. Concomitant wall-thickening abnormalities occurred in 83% of segments with fixed perfusion defects, mirrored by a reduction in wall motion in 91% of segments analyzed. Right ventricular ejection fraction was correlated with age (R = 0.62; p = 0.002), and with wall-thickening abnormalities (R = 0.60; p < 0.005).
CONCLUSIONS
Reversible and fixed perfusion defects with concordant regional wall motion abnormalities occur in the right (systemic) ventricle 10 to 20 years after Mustard repair for transposition of the great arteries; this may be important in the pathogenesis of late right ventricular dysfunction in this group.
The MiniBooNE Collaboration reports a search for nu_{micro} and nuover_{micro} disappearance in the Deltam;{2} region of 0.5-40 eV;{2}. These measurements are important for constraining models with ...extra types of neutrinos, extra dimensions, and CPT violation. Fits to the shape of the nu_{micro} and nuover_{micro} energy spectra reveal no evidence for disappearance at the 90% confidence level (C.L.) in either mode. The test of nuover_{micro} disappearance probes a region below Deltam;{2} = 40 eV;{2} never explored before.
We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a deuterium target. The muon angular distributions in the dilepton rest frame have ...been measured over the kinematic range 4.5<m{mu mu}<15 GeV/c{2}, 0<p{T}<4 GeV/c, and 0<x{F}<0.8. No significant cos2phi dependence is found in these proton-induced Drell-Yan data, in contrast with the situation for pion-induced Drell-Yan data. The data are compared with expectations from models which attribute the cos2phi distribution to a QCD vacuum effect or to the presence of the transverse-momentum-dependent Boer-Mulders structure function h{1}{perpendicular}. Constraints on the magnitude of the sea-quark h{1}{perpendicular} structure functions are obtained.
Objective: Because of the complexity of traditional 1- and 2-patch techniques for the repair of complete atrioventricular septal defect, we modified our repair technique to avoid the use of any ...ventricular septal patch material. We report our prospective experience with this simplified 1-patch technique.
Method: Forty-seven consecutive patients between May 1995 and August 1998 underwent repair with the use of this technique without modification. Repair was done in all patients by direct suturing of the common atrioventricular valve leaflets to the crest of the ventricular septum. No division of valve leaflets was necessary. A single pericardial patch was used to close the defect in the atrial septal component. Follow-up included electrocardiography and echocardiographic assessment of ventricular function, atrioventricular valve function, and adequacy of the left ventricular outflow tract.
Results: There were 2 deaths (4%), only 1 cardiac related, in the series. There were 17 male patients and 30 female patients. Mean age at repair was 5.6 months (median, 3.4 months). Associated lesions were repaired in 19 patients (40%). Mean follow-up was 1.85 years (median, 1.9 years). There was no heart block. There were no significant residual ventricular septal defects detected and no left ventricular outflow tract obstruction seen on echocardiography in any patient to date. Mitral valve status after operation was assessed as no incompetence in 13 patients (28%), minimal in 19 patients (40%), mild in 12 patients (26%), and moderate in 3 patients (6%).
Conclusion: The repair of complete atrioventricular septal defect by direct suturing of the atrioventricular valve leaflets to the crest of the ventricular septum with a single-patch technique greatly simplifies the repair and does not lead to left ventricular outflow tract obstruction nor interfere with valve function. (J Thorac Cardiovasc Surg 1999;118:642-7)
The phenomenon of posttraumatic growth (PTG) and contributing factors were studied in a sample of 10 Iraq and Afghanistan veterans using a phenomenological methodology. Veterans were included in the ...study if they reported experiencing moderate to high levels of PTG in at least two of the five domains of growth identified in PTG literature. Through semi-structured interviews, participants reported that the factors which mostly contributed to their growth were: (a) remaining connected to veterans or the military, (b) connecting with others and feeling supported by loved ones, (c) working with a counselor, (d) time, and (e) developmental reading. Seven participants reported symptoms of posttraumatic stress disorder (PTSD). The narratives provided by participants indicate the importance for clinicians to ask clients about PTG, in addition to PTSD symptoms. This article concludes with the description of clinical implications for working with veterans who have experienced combat-related trauma, and recommendations for future research.
Background Patients with systemic ventricles of right ventricular morphology are at high risk of contractile dysfunction, the cause of which has not been fully elucidated. Objective To assess whether ...ischaemia or infarction contributes to ventricular impairment in unoperated patients with uncomplicated congenitally corrected transposition of the great arteries (TGA) by studying myocardial perfusion and function. Setting Paediatric and adult congenital cardiac clinics of a tertiary referral centre. Patients Five patients with congenitally corrected TGA but without associated structural cardiac defects (aged 3.5 to 34 years). Interventions Maximal exercise stress testing using standard or modified Bruce protocols. Sestamibi (technetium-99m methoxy isobutyl isonitrile) scanning after isotope injection at maximal exercise and rest. Main outcome measures Maximum exercise capacity; right ventricular myocardial perfusion, regional wall motion, and thickening; right ventricular ejection fraction. Results The two youngest patients (3.5 and 11 years) had normal exercise capacity for age, while the others had reduced exercise performance. Sestamibi scanning showed reversible myocardial ischaemia in four patients and fixed defects indicating infarction in five. Irreversible defects were mostly associated with impaired wall motion and thickening. The ejection fraction was normal (65%) in the youngest patient but < 55% in the others (mean (SD) 47(11)%). Conclusions Patients with unoperated congenitally corrected TGA have a high prevalence of myocardial perfusion defects, with consequent abnormalities of regional wall motion and thickening, and impaired ventricular contractility. These data suggest that ischaemia and infarction are important in the pathogenesis of ventricular failure in this condition.
PDF
