71 research outputs found
Diameter-Selective Dispersion of Carbon Nanotubes via Polymers: A Competition between Adsorption and Bundling
The mechanism of the selective dispersion of single-walled carbon nanotubes
(CNTs) by polyfluorene polymers is studied in this paper. Using extensive
molecular dynamics simulations, it is demonstrated that diameter selectivity is
the result of a competition between bundling of CNTs and adsorption of polymers
on CNT surfaces. The preference for certain diameters corresponds to local
minima of the binding energy difference between these two processes. Such
minima in the diameter dependence occur due to abrupt changes in the CNT's
coverage with polymers and their calculated positions are in quantitative
agreement with preferred diameters, reported experimentally. The presented
approach defines a theoretical framework for the further understanding and
improvement of dispersion/extraction processes.Comment: 22 pages, 5 figures, ACS Nano (2015
No One Left Behind: Real-World Federated Class-Incremental Learning
Federated learning (FL) is a hot collaborative training framework via
aggregating model parameters of decentralized local clients. However, most FL
methods unreasonably assume data categories of FL framework are known and fixed
in advance. Moreover, some new local clients that collect novel categories
unseen by other clients may be introduced to FL training irregularly. These
issues render global model to undergo catastrophic forgetting on old
categories, when local clients receive new categories consecutively under
limited memory of storing old categories. To tackle the above issues, we
propose a novel Local-Global Anti-forgetting (LGA) model. It ensures no local
clients are left behind as they learn new classes continually, by addressing
local and global catastrophic forgetting. Specifically, considering tackling
class imbalance of local client to surmount local forgetting, we develop a
category-balanced gradient-adaptive compensation loss and a category
gradient-induced semantic distillation loss. They can balance heterogeneous
forgetting speeds of hard-to-forget and easy-to-forget old categories, while
ensure consistent class-relations within different tasks. Moreover, a proxy
server is designed to tackle global forgetting caused by Non-IID class
imbalance between different clients. It augments perturbed prototype images of
new categories collected from local clients via self-supervised prototype
augmentation, thus improving robustness to choose the best old global model for
local-side semantic distillation loss. Experiments on representative datasets
verify superior performance of our model against comparison methods. The code
is available at https://github.com/JiahuaDong/LGA.Comment: 17 pages, 8 figure
An optimization study of estimating blood pressure models based on pulse arrival time for continuous monitoring
Continuous blood pressure (BP) monitoring has a significant meaning for the prevention and early diagnosis of cardiovascular disease. However, under different calibration methods, it is difficult to determine which model is better for estimating BP. This study was firstly designed to reveal a better BP estimation model by evaluating and optimizing different BP models under a justified and uniform criterion, i.e., the advanced point-to-point pairing method (PTP). Here, the physical trial in this study caused the BP increase largely. In addition, the PPG and ECG signals were collected while the cuff bps were measured for each subject. The validation was conducted on four popular vascular elasticity (VE) models (MK-EE, L-MK, MK-BH, and dMK-BH) and one representative elastic tube (ET) model, i.e., M-M. The results revealed that the VE models except for L-MK outperformed the ET model. The linear L-MK as a VE model had the largest estimated error, and the nonlinear M-M model had a weaker correlation between the estimated BP and the cuff BP than MK-EE, MK-BH, and dMK-BH models. Further, in contrast to L-MK, the dMK-BH model had the strongest correlation and the smallest difference between the estimated BP and the cuff BP including systolic blood pressure (SBP) and diastolic blood pressure (DBP) than others. In this study, the simple MK-EE model showed the best similarity to the dMK-BH model. There were no significant changes between MK-EE and dMK-BH models. These findings indicated that the nonlinear MK-EE model with low estimated error and simple mathematical expression was a good choice for application in wearable sensor devices for cuff-less BP monitoring compared to others
Doping inorganic ions to regulate bioactivity of Ca–P coating on bioabsorbable high purity magnesium
AbstractPerformance of biomaterials was strongly affected by their surface properties and could be designed artificially to meet specific biomedical requirements. In this study, F−(F), SiO42−(Si), or HCO3−(C)-doped Ca–P coatings were fabricated by biomimetic deposition on the surface of biodegradable high-purity magnesium (HP Mg). The crystalline phases, morphologies and compositions of Ca–P coatings had been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The biomineralization and corrosion resistance of doped Ca–P coatings had also been investigated. The results showed that the Ca–P coating with or without doped elements mainly contained the plate-like dicalcium phosphate dehydrate (DCPD) phase. The doped F, Si, or C changed the surface morphology of Ca–P coatings after mineralization. Doped F enhanced the mineralization of Ca–P coating, and doped Si retarded the mineralization of Ca–P coating. However, H2 evolution of HP Mg discs with different Ca–P coatings was close to 0.4–0.7ml/cm2 after two-week immersion. That meant that the corrosion resistance of the Ca–P coatings with different or without doped elements did not change significantly
In Situ Preservation Fraction of Parathyroid Gland in Thyroidectomy: A Cohort Retrospective Study
Background and Objectives. Parathyroid failure is the most common symptom after thyroidectomy. To prevent it, a gland was preserved in situ or an ischemic one was autotransplanted. This study explored the relationship between in situ preservation of the parathyroid gland and gland failure. Methods. Consecutive patients who underwent initial total thyroidectomy were enrolled retrospectively in a prospectively maintained database. Patients were divided into groups by parathyroid gland remaining in situ fraction (PGRIF) (PGRIF = number of in situ glands/(total number of identified glands − number of glands in specimen). Patients were graded by tertiles and followed at least one year after surgery. Results. 559 patients were included. PGRIF is significantly inversely associated with transient hypoparathyroidism, protracted hypoparathyroidism, and postoperative hypocalcemia. PGRIF was identified as an independent risk factor for transient hypoparathyroidism, protracted hypoparathyroidism, and postoperative hypocalcemia (OR=0.177, 0.190, and 0.330, resp.). Autotransplantation of parathyroid gland would not affect the calcium level in the long term. Conclusion. In situ preservation of parathyroid gland is crucial for parathyroid function. Less preserved is the independent risk factor for postoperative hypoparathyroidism and hypocalcemia, resulting in a worse function of parathyroid gland in the long term
Post-treatment neutrophil-lymphocyte ratio independently predicts amputation in critical limb ischemia without operation
OBJECTIVES: Limited information is available concerning the post-treatment neutrophil-lymphocyte ratio in critical limb ischemia patients who receive conservative therapy. Accordingly, this study was designed to evaluate the predictive value of the post-treatment neutrophil-lymphocyte ratio in critical limb ischemia patients without surgery. METHOD: From January 2009 to January 2011, critical limb ischemia patients were admitted to a vascular center. The demographic data, patient histories, comorbidities and risk factors were documented, and the differential cell count was determined at admission and seven days later after conservative therapy. The cutoff value of the post-treatment neutrophil-lymphocyte ratio was determined by an ROC curve. Patients were divided into groups A and B according to the cutoff value. Amputation-free survival was compared between groups. Univariate and multivariate analyses were used to identify independent risk factors. RESULT: A total of 172 patients were identified with a mean age 71.98±10.09 years; among them, 122 were male. A value of 3.8 was identified as the cutoff value of the post-treatment neutrophil-lymphocyte ratio. Groups A (post-treatment neutrophil-lymphocyte ratio ≥3.8) and B (post-treatment neutrophil-lymphocyte rati
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