Background
Recent studies demonstrate high offer decline and organ non‐utilization rates are associated with increased pediatric heart transplant waitlist mortality. We sought to determine which ...donor, candidate, and offer specific variables most importantly influenced these decisions using only data available at the time of each offer.
Methods
Retrospective review of pediatric (<18 years) heart donor offers made to pediatric candidates in the United States between 2010 and 2020. In addition to standard donor, candidate, and offer data available in UNOS, we extracted objective and qualitative valvar and myocardial function data from all available donor echocardiogram reports.
Results
During the study period, 5625 pediatric donor hearts produced 30 156 offers to 4905 unique candidates, of which 88.7% of all offers were declined and 39.2% of organs were not utilized by pediatric waitlisted candidates. Of the 60.8% utilized hearts, 89.7% had a ‘cumulatively’ normal echocardiogram at the time of offer acceptance; 62.9% of hearts not utilized for a pediatric candidate also had a cumulatively normal final echocardiogram. Random forest and logistic regression modeling demonstrated good predictive performance (AUROC ≥0.83) of likelihood to accept when utilizing donor, candidate, and offer specific variables. SHAP variable importance scores demonstrated number of prior offer declines and candidate institution's prior year acceptance rates as the two most important variables influencing offer decisions.
Conclusions
Behavioral economics appear to play a significant role in pediatric heart transplant candidate institutions' acceptance practices, even when considering the arguably healthier pediatric donor population. Removal of prior institution's decisions from DonorNet may help increase donor utilization.
We report the first observation of the parity-violating gamma-ray asymmetry A_{γ}^{np} in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the ...Spallation Neutron Source at Oak Ridge National Laboratory. A_{γ}^{np} isolates the ΔI=1, ^{3}S_{1}→^{3}P_{1} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured A_{γ}^{np}=-3.0±1.4(stat)±0.2(syst)×10^{-8}, which implies a DDH weak πNN coupling of h_{π}^{1}=2.6±1.2(stat)±0.2(syst)×10^{-7} and a pionless EFT constant of C^{^{3}S_{1}→^{3}P_{1}}/C_{0}=-7.4±3.5(stat)±0.5(syst)×10^{-11} MeV^{-1}. We describe the experiment, data analysis, systematic uncertainties, and implications of the result.
Nab: Measurement principles, apparatus and uncertainties Počanić, Dinko; Alarcon, R.; Alonzi, L.P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2009, Letnik:
611, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Nab collaboration will perform a precise measurement of
a, the electron–neutrino correlation parameter, and
b, the Fierz interference term in neutron beta decay, in the Fundamental Neutron ...Physics Beamline at the SNS, using a novel electric/magnetic field spectrometer and detector design. The experiment is aiming at the
10
-
3
accuracy level in
Δ
a
/
a
, and will provide an independent measurement of
λ
=
G
A
/
G
V
, the ratio of axial-vector to vector coupling constants of the nucleon. Nab also plans to perform the first ever measurement of
b in neutron decay, which will provide an independent limit on the tensor weak coupling.
Experimental results on pion decays obtained with the PIBETA spectrometer at the Paul Scherrer Institute (PSI) are reviewed. For pion beta decay π
+
→ π
0
е
+
ν (πβ), a precision measurement of ...relative probability yields Г(πβ) = 1.036 ± 0.004(stat) ± 0.004(syst) ± 0.003(π
+
→е
+
ν) × 10
–8
, which implies
V
ud
= 0.9728(30) for the corresponding element of the Cabibbo–Kobayashi–Maskawa mixing matrix. Using a sample of 65 × 10
3
events, relative probability of the π
+
→е
+
νγ radiative pion decay (RPD) in the kinematic region of
E
γ
> 10 MeV and
θ
eγ
> 40° is measured as
B
exp
= 73.86(54) × 10
–8
. A statistical analysis of measured
E
e
+
and
E
γ
distributions for this decay yield the values
F
V
= 0.0258(17) and
F
A
= 0.0117(17) for the pion weak formfactors. Assuming that
F
V
linearly depends on the е
+
ν invariant mass
q
2
as
F
V
(
q
2
) =
F
V
(0)(1 +
aq
2
), the slope parameter is extracted as
а
= 0.10(6). The pion polarizability and neutral-pion lifetime are estimated as
α
E
= 2.78(10) × 10
–4
fm
3
and τ(π
0
) = (8.5 ± 1.1) × 10
–17
s, respectively. The data for decays π
+
→ е
+
ν and
μ
+
→
e
+
v
v
¯
γ
have been collected and are being processed. The follow-up PEN experiment aims at reducing the uncertainty on the π
+
→ е
+
ν relative probability by almost an order of magnitude (to 5 × 10
–4
).
In 2018, Alonzi, Drougas, and Condon ("ADC") developed a simple macroeconomic model to analyze the effect of a less equal income distribution. This paper builds upon that paper by constructing a ...model incorporating a rising absolute income in both the high and low groups while at the same time allowing a higher proportion of income to go to the high-income group, but a lower proportion go to the low-income group. Notably, we find that the qualitative results of the "Reverse Robin Hood" case remain in the "Rising Tide" case but there are quantitative differences.
The electromagnetic calorimeter for the new muon (g−2) experiment at Fermilab will consist of arrays of PbF2 Cherenkov crystals read out by large-area silicon photo-multiplier (SiPM) sensors. We ...report here on measurements and simulations using 2.0–4.5GeV electrons with a 28-element prototype array. All data were obtained using fast waveform digitizers to accurately capture signal pulse shapes vs. energy, impact position, angle, and crystal wrapping. The SiPMs were gain matched using a laser-based calibration system, which also provided a stabilization procedure that allowed gain correction to a level of 10−4 per hour. After accounting for longitudinal fluctuation losses, those crystals wrapped in a white, diffusive wrapping exhibited an energy resolution σ/E of (3.4±0.1)%/E/GeV, while those wrapped in a black, absorptive wrapping had (4.6±0.3)%/E/GeV. The white-wrapped crystals—having nearly twice the total light collection—display a generally wider and impact-position-dependent pulse shape owing to the dynamics of the light propagation, in comparison to the black-wrapped crystals, which have a narrower pulse shape that is insensitive to impact position.
The calorimeter system of the new muon g-2 experiment at Fermilab Alonzi, L.P.; Anastasi, A.; Bjorkquist, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The electromagnetic calorimeter for the new muon (g−2) experiment at Fermilab will consist of arrays of PbF2 Čerenkov crystals read out by large-area silicon photo-multiplier (SiPM) sensors. We ...report here the requirements for this system, the achieved solution and the results obtained from a test beam using 2.0–4.5GeV electrons with a 28-element prototype array.
The calorimeter system of the new muon g-2 experiment at Fermilab Alonzi, L. P.; Anastasi, A.; Bjorkquist, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2015, Letnik:
824, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The electromagnetic calorimeter for the new muon (g–2) experiment at Fermilab will consist of arrays of PbF2 Cerenkov crystals read out by large-area silicon photo-multiplier (SiPM) sensors. Here, we ...report here the requirements for this system, the achieved solution and the results obtained from a test beam using 2.0–4.5 GeV electrons with a 28-element prototype array.
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