268 research outputs found
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Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases
Airborne estimates of greenhouse gas emissions are becoming more
prevalent with the advent of rapid commercial development of trace gas
instrumentation featuring increased measurement accuracy, precision, and
frequency, and the swelling interest in the verification of current emission
inventories. Multiple airborne studies have indicated that emission
inventories may underestimate some hydrocarbon emission sources in US oil-
and gas-producing basins. Consequently, a proper assessment of the accuracy
of these airborne methods is crucial to interpreting the meaning of such
discrepancies. We present a new method of sampling surface sources of any
trace gas for which fast and precise measurements can be made and apply it to
methane, ethane, and carbon dioxide on spatial scales of ∼ 1000 m,
where consecutive loops are flown around a targeted source region at
multiple altitudes. Using Reynolds decomposition for the scalar
concentrations, along with Gauss's theorem, we show that the method
accurately accounts for the smaller-scale turbulent dispersion of the local
plume, which is often ignored in other average mass balance methods. With
the help of large eddy simulations (LES) we further show how the circling
radius can be optimized for the micrometeorological conditions encountered
during any flight. Furthermore, by sampling controlled releases of methane
and ethane on the ground we can ascertain that the accuracy of the method, in
appropriate meteorological conditions, is often better than 10 %, with
limits of detection below 5 kg h−1 for both methane and ethane. Because of the FAA-mandated minimum flight safe altitude of 150 m, placement of the aircraft is critical to preventing a large portion of the emission plume from flowing underneath the lowest aircraft sampling altitude, which is generally the leading source of uncertainty in these measurements. Finally, we show how the accuracy of the method is strongly dependent on the number of sampling loops and/or time spent sampling the source plume
and processes with polarized muons and supersymmetric grand unified theories
and processes are
analyzed in detail with polarized muons in supersymmetric grand unified
theories. We first present Dalitz plot distribution for decay based on effective Lagrangian with general
lepton-flavor-violating couplings and define various P- and T-odd asymmetries.
We calculate branching ratios and asymmetries in supersymmetric SU(5) and
SO(10) models taking into account complex soft supersymmetry breaking terms.
Imposing constraints from experimental bounds on the electron, neutron and
atomic electric dipole moments, we find that the T-odd asymmetry for can be 15% in the SU(5) case. P-odd asymmetry with respect
to muon polarization for varies from -20% to -100%
for the SO(10) model while it is in the SU(5) case. We also show that
the P-odd asymmetries in and the ratio of
and branching
fractions are useful to distinguish different models.Comment: 52 pages, 15 figure
Japanese haemodialysis anaemia management practices and outcomes (1999–2006): results from the DOPPS
Background. Japanese haemodialysis (HD) patients not only have a very low mortality and hospitalization risk but also low haemoglobin (Hb) levels. Internationally, anaemia is associated with mortality, hospitalization and health-related quality of life (QoL) measures of HD patients
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Combining macula clinical signs and patient characteristics for age-related macular degeneration diagnosis: a machine learning approach
Background: To investigate machine learning methods, ranging from simpler interpretable techniques to complex (non-linear) “black-box” approaches, for automated diagnosis of Age-related Macular Degeneration (AMD).
Methods: Data from healthy subjects and patients diagnosed with AMD or other retinal diseases were collected during routine visits via an Electronic Health Record (EHR) system. Patients’ attributes included demographics and, for each eye, presence/absence of major AMD-related clinical signs (soft drusen, retinal pigment epitelium, defects/ pigment mottling, depigmentation area, subretinal haemorrhage, subretinal fluid, macula thickness, macular scar, subretinal fibrosis). Interpretable techniques known as white box methods including logistic regression and decision trees as well as less interpreitable techniques known as black box methods, such as support vector machines (SVM), random forests and AdaBoost, were used to develop models (trained and validated on unseen data) to diagnose AMD. The gold standard was confirmed diagnosis of AMD by physicians. Sensitivity, specificity and area under the receiver operating characteristic (AUC) were used to assess performance.
Results: Study population included 487 patients (912 eyes). In terms of AUC, random forests, logistic regression and adaboost showed a mean performance of (0.92), followed by SVM and decision trees (0.90). All machine learning models identified soft drusen and age as the most discriminating variables in clinicians’ decision pathways to diagnose AMD. C
Conclusions: Both black-box and white box methods performed well in identifying diagnoses of AMD and their decision pathways. Machine learning models developed through the proposed approach, relying on clinical signs identified by retinal specialists, could be embedded into EHR to provide physicians with real time (interpretable) support
Rotational structures and the wobbling mode in Ta167
Excited states in the neutron-deficient nucleus Ta167 were studied through the Sn120(V51,4n) reaction. Twelve rotational bands have been observed and the relative excitation energy of each sequence is now known owing to the multiple interband connections. Several quasineutron alignments were observed that aided in the quasiparticle assignments of these bands. The resulting interpretation is in line with observations in neighboring nuclei. Trends in the wobbling phonon energy seen in Lu161,163,165,167 and Ta167 are also discussed and particle-rotor model calculations (assuming constant moments of inertia) are found to be inconsistent with the experimental data
The Effect of Service on Research Performance: A Study on Italian Academics in Management
Academics all over the world are feeling the increasing pressure to attain satisfactory research performance. Since research is not the only activity required of academics, though, the debate on how it may be coupled with other knowledge transfer activities like teaching, patenting, and dissemination has been captivating scholars interested in higher education. Literature is surprisingly silent about the interplay between research performance and other roles and tasks that faculty are expected to carry out, namely academic citizenship, intended as the service that they provide to their institution, to the scientific community, and to the larger society. Through a negative binomial regression conducted on 692 Italian academics in management, this paper investigates both the direct and moderating effect exerted by academic citizenship on the relationship between research performance in two subsequent evaluation exercises, thus advancing our knowledge of the relationship between research and service. Findings show that institutional service acts as a pure moderator, discipline-based service is a quasi-moderator, while public service exerts only a direct negative effect on research performance. In light of the emergent interplay between research and service, the necessity to boost reflection on academic citizenship is discussed and suggestions for its acknowledgement and advancement are formulated
TLR9-Dependent and Independent Pathways Drive Activation of the Immune System by Propionibacterium Acnes
Propionibacterium acnes is usually a relatively harmless commensal. However, under certain, poorly understood conditions it is implicated in the etiology of specific inflammatory diseases. In mice, P. acnes exhibits strong immunomodulatory activity leading to splenomegaly, intrahepatic granuloma formation, hypersensitivity to TLR ligands and endogenous cytokines, and enhanced resistance to infection. All these activities reach a maximum one week after P. acnes priming and require IFN-γ and TLR9. We report here the existence of a markedly delayed (1–2 weeks), but phenotypically similar TLR9-independent immunomodulatory response to P. acnes. This alternative immunomodulation is also IFN-γ dependent and requires functional MyD88. From our experiments, a role for MyD88 in the IFN-γ-mediated P. acnes effects seems unlikely and the participation of the known MyD88-dependent receptors, including TLR5, Unc93B-dependent TLRs, IL-1R and IL-18R in the development of the alternative response has been excluded. However, the crucial role of MyD88 can partly be attributed to TLR2 and TLR4 involvement. Either of these two TLRs, activated by bacteria and/or endogenously generated ligands, can fulfill the required function. Our findings hint at an innate immune sensitizing mechanism, which is potentially operative in both infectious and sterile inflammatory disorders
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