1,965 research outputs found
Estimating Trotter Approximation Errors to Optimize Hamiltonian Partitioning for Lower Eigenvalue Errors
One of the ways to encode many-body Hamiltonians on a quantum computer to
obtain their eigen-energies through Quantum Phase Estimation is by means of the
Trotter approximation. There were several ways proposed to assess the quality
of this approximation based on estimating the norm of the difference between
the exact and approximate evolution operators. Here, we would like to explore
how these different error estimates are correlated with each other and whether
they can be good predictors for the true Trotter approximation error in finding
eigenvalues. For a set of small molecular systems we calculated the exact
Trotter approximation errors of the first order Trotter formulas for the ground
state electronic energies. Comparison of these errors with previously used
upper bounds show almost no correlation over the systems and various
Hamiltonian partitionings. On the other hand, building the Trotter
approximation error estimation based on perturbation theory up to a second
order in the time-step for eigenvalues provides estimates with very good
correlations with the Trotter approximation errors. The developed perturbative
estimates can be used for practical time-step and Hamiltonian partitioning
selection protocols, which are paramount for an accurate assessment of
resources needed for the estimation of energy eigenvalues under a target
accuracy.Comment: 3 figure
Effects of Bulk Viscosity in Non-linear Bubble Dynamics
The non-linear bubble dynamics equations in a compressible liquid have been
modified considering the effects of compressibility of both the liquid and the
gas at the bubble interface. A new bubble boundary equation has been derived,
which includes a new term resulted from the liquid bulk viscosity effects. The
influence of this term has been numerically investigated considering the
effects of water vapor and chemical reactions on the bubble evolution. The
results clearly indicate that the new term has an important damping role at the
collapse, so that its consideration decreases the amplitude of the bubble
rebounds after the collapse. This damping feature is more remarkable for higher
deriving pressures.Comment: 4 pages, 7 figure
Robotic-arm assisted lateral unicompartmental knee arthroplasty: 5-Year outcomes & survivorship
INTRODUCTION: Robotic-arm assisted unicompartmental knee arthroplasty (RA-UKA) has demonstrated accurate component positioning and excellent outcomes for medial components. However, there is a paucity of literature on lateral compartment RA-UKA. The purpose of our study was to assess the midterm clinical outcomes and survivorship of lateral RA-UKA.
METHODS: This study was a retrospective review of a single-center prospectively maintained cohort of 33 patients (36 knees) indicated for lateral UKA. Perioperative, and postoperative two- and five-year Knee injury Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Score (WOMAC), and Forgotten Joint Score (FJS) patient reported outcome measures were collected. Five-year follow-up was recorded in 29 patients (32 knees).
RESULTS: Mean follow up was 5.1 ± 0.1 years. Mean age and BMI was 70.9 ± 7.2 years and 29.0 ± 4.2 kg/m2, respectively. At discharge, mean distance walked was 273.4 ± 70.4 feet, and mean pain score was 2.0 ± 2.5. At 2-year follow up, mean KOOS, WOMAC, and FJS were 75.1 ± 13.5, 15.0 ± 7.2, and 81.0 ± 23.3, respectively. At 5-year follow up, mean KOOS, WOMAC, and FJS were 75.3 ± 14.6, 14.9 ± 5.0, and 75.8 ± 27.4, respectively. Mean change in KOOS and WOMAC were 35.6 ± 27.1 and 11.7 ± 13.4 (p\u3c .001 and p\u3c .001). 94% of patients were very satisfied/satisfied, 3% neutral, and 3% dissatisfied. 91% met activity expectations, and 59% were more active than before. Survivorship was 100% at 5 years.
DISCUSSION: In this study, lateral RA-UKA demonstrated significantly improved clinical outcomes, high patient satisfaction, met expectations, and excellent functional recovery at midterm follow up. Comparative studies are needed to determine differences between robotic-assisted and conventional lateral UKA, as well as TKA
Validating a novel score based on interaction between ACLF grade and MELD score to predict waitlist mortality
Background and Aim:
Among candidates listed for liver transplant (LT), MELD score may not capture acute on chronic liver failure (ACLF) severity. Data on interaction between ACLF and MELD score in predicting waitlist (WL) mortality are scanty. /
Methods:
UNOS database (01/2002 to 06/2018) on LT listings for adults with cirrhosis and ACLF (without HCC) was analyzed. ACLF grades 1, 2, 3a, and 3b- were defined using modified EASL-CLIF criteria. /
Results:
Of 18,416 candidates with ACLF at listing (mean age 54 years, 69% males, 63% Caucasians), 90-d WL mortality (patient death or being too sick for LT) was 21.6% (18%, 20%, 25%, and 39% for ACLF grades 1, 2, 3a, and 3b respectively). Fine and Gray regression model identified interaction between MELD and ACLF grade, with higher impact of ACLF at lower MELD score. Other variables included candidate’s age, gender, liver disease etiology, listing MELD, ACLF grade, obesity, and performance status. A score developed using parameter estimates from the interaction model on the derivation cohort (N=9181) stratified the validation cohort (N=9235) to four quartiles Q1 (score 15.50). WL mortality increased with each quartile from 13%, 18%, 23%, and 36% respectively. Observed versus expected deciles on WL mortality in validation cohort showed good calibration (goodness of fit P=0.98) and correlation (R=0.99). /
Conclusion:
Among selected candidates who are in ACLF at listing, MELD score and ACLF interact in predicting cumulative risk of 90-d WL mortality, with higher impact of ACLF grade at lower listing MELD score. Validating these findings in large prospective studies will support to factor in both MELD and ACLF in prioritizing transplant candidates and allocation of liver grafts
5-Year Survivorship and Outcomes of Robotic-Arm-Assisted Medial Unicompartmental Knee Arthroplasty
Purpose: While unicompartmental knee arthroplasty (UKA) has demonstrated benefits over total knee arthroplasty (TKA) in selected populations, component placement continues to be challenging with conventional surgical instruments, resulting in higher early failure rates. Robotic-arm-assisted UKA (RA-UKA) has shown to be successful in component positioning through preop planning and intraop adjustability. The purpose of this study is to assess the 5-year clinical outcomes of medial RA-UKA.
Methods: This study was a retrospective review of a single-center prospectively maintained cohort of 133 patients (146 knees) indicated for medial UKA from 2009 to 2013. Perioperative data and 2- and 5-year Knee injury Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Score (WOMAC), and Forgotten Joint Score (FJS) outcome measures were collected. Five-year follow-up was recorded in 119 patients (131 knees).
Results: Mean follow-up was 5.1 ± 0.2 years. Mean age and BMI were 68.0 ± 8.1 years and 29.3 ± 4.7 kg/m(2), respectively. At 2-year follow-up, mean KOOS, WOMAC, and FJS were 71.5 ± 15.3, 14.3 ± 7.9, and 79.1 ± 25.8, respectively. At 5-year follow-up, mean KOOS, WOMAC, and FJS were 71.6 ± 15.2, 14.2 ± 7.9, and 80.9 ± 25.1, respectively. Mean change in KOOS and WOMAC was 34.6 ± 21.4 and 11.0 ± 13.6, respectively (p \u3c 0.001 and p \u3c 0.001). For patient satisfaction at last follow-up, 89% of patients were very satisfied/satisfied and 5% were dissatisfied. For patient activity expectations at last follow-up, 85% met activity expectations, 52% were more active than before, 25% have the same level of activity, 23% were less active than before, and 89% were walking without support. All patients returned to driving after surgery at a mean 15.2 ± 9.4 days. Survivorship was 95% (95% CI 0.91-0.98) at 5 years. One knee (1%) had a patellofemoral revision, two knees (1.3%) were revised to different partial knee replacements, and five knees (3.4%) were converted to TKA.
Conclusion: Overall, medial RA-UKA demonstrated improved patient-recorded outcomes, high patient satisfaction, met expectations, and excellent functional recovery. Midterm survivorship was excellent. Longitudinal follow-up is needed to evaluate long-term outcomes of robotic-arm-assisted UKA procedures
Pioglitazone corrects dysregulation of skeletal muscle mitochondrial proteins involved in ATP synthesis in type 2 diabetes
Context: In this study, we aimed to identify the determinants of mitochondrial dysfunction in skeletal muscle (SKLM) of subjects with type 2 diabetes (T2DM), and to evaluate the effect of pioglitazone (PIO) on SKLM mitochondrial proteome. Methods: Two different groups of adults were studied. Group I consisted of 8 individuals with normal glucose tolerance (NGT) and 8 with T2DM, subjected to SKLM mitochondrial proteome analysis by 2D-gel electrophoresis followed by mass spectrometry-based protein identification. Group II included 24 individuals with NGT and 24 with T2DM, whose SKLM biopsies were subjected to immunoblot analysis. Of the 24 subjects with T2DM, 20 were randomized to receive placebo or PIO (15 mg daily) for 6 months. After 6 months of treatment, SKLM biopsy was repeated. Results: Mitochondrial proteomic analysis on Group I revealed that several mitochondrial proteins involved in oxidative metabolism were differentially expressed between T2DM and NGT groups, with a downregulation of ATP synthase alpha chain (ATP5A), electron transfer flavoprotein alpha-subunit (ETFA), cytochrome c oxidase subunit VIb isoform 1 (CX6B1), pyruvate dehydrogenase protein X component (ODPX), dihydrolipoamide dehydrogenase (DLDH), dihydrolipoamide-S-succinyltransferase (DLST), and mitofilin, and an up-regulation of hydroxyacyl-CoA-dehydrogenase (HCDH), 3,2-trans-enoyl-CoA-isomerase (D3D2) and delta3,5-delta2,4-dienoyl-CoA-isomerase (ECH1) in T2DM as compared to NGT subjects. By immunoblot analysis on SKLM lysates obtained from Group II we confirmed that, in comparison to NGT subjects, those with T2DM exhibited lower protein levels of ATP5A (−30%, P = 0.006), ETFA (−50%, P = 0.02), CX6B1 (−30%, P = 0.03), key factors for ATP biosynthesis, and of the structural protein mitofilin (−30%, P = 0.01). T2DM was associated with a reduced abundance of the enzymes involved in the Krebs cycle DLST and ODPX (−20%, P ≤ 0.05) and increased levels of HCDH and ECH1, enzymes implicated in the fatty acid catabolism (+30%, P ≤ 0.05). In subjects with type 2 diabetes treated with PIO for 6 months we found a restored SKLM protein abundance of ATP5A, ETFA, CX6B1, and mitofilin. Moreover, protein levels of HCDH and ECH1 were reduced by −10% and − 15% respectively (P ≤ 0.05 for both) after PIO treatment. Conclusion: Type 2 diabetes is associated with reduced levels of mitochondrial proteins involved in oxidative phosphorylation and an increased abundance of enzymes implicated in fatty acid catabolism in SKLM. PIO treatment is able to improve SKLM mitochondrial proteomic profile in subjects with T2DM
Mechanisms for Stable Sonoluminescence
A gas bubble trapped in water by an oscillating acoustic field is expected to
either shrink or grow on a diffusive timescale, depending on the forcing
strength and the bubble size. At high ambient gas concentration this has long
been observed in experiments. However, recent sonoluminescence experiments show
that in certain circumstances when the ambient gas concentration is low the
bubble can be stable for days. This paper presents mechanisms leading to
stability which predict parameter dependences in agreement with the
sonoluminescence experiments.Comment: 4 pages, 3 figures on request (2 as .ps files
A QCD Sum Rule Approach to the Contribution to the Radiative Decay
QCD sum rules are used to calculate the contribution of short-distance
single-quark transition , to the amplitudes of the
hyperon radiative decay, . We re-evaluate the
Wilson coefficient of the effective operator responsible for this transition.
We obtain a branching ratio which is comparable to the unitarity limit.Comment: 15 pages, Revtex, 13 figures available as a uuencoded, gz-compressed
ps fil
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