2,362 research outputs found
Commercial frying oils: characteristics during frying and models for prediction of oil degradation
Higher-order modulation instability and multi-Akhmediev breathers of Manakov equations: Frequency jumps over the stable gaps between the instability bands
We study higher-order modulation instability phenomena in the frame of
Manakov equations. Evolution that starts with a single pair of sidebands
expands over several higher harmonics. The choice of initial pair of sidebands
influences the structure of unstable frequency components and changes
drastically the wave evolution leading, in some cases, to jumps across spectral
components within the discrete spectrum. This complex dynamics includes several
growth-decay cycles of evolution. We show this using numerical simulations of
the MI process and confirm the results using the exact multi-Akhmediev breather
solutions. Detailed explanation of the observed phenomena are given.Comment: 9 pages, 6 figure
Superior Mesenteric Artery Syndrome: A Single-institution Experience
Background:Superior mesenteric artery syndrome (SMAS) is a rare disease in adult. SMAS is characterized by acute, or, more commonly, chronic nonspecific symptoms due to duodenal obstruction and severe malnutrition with reduced arterio-mesenteric angle and distance. Surgical treatment may be necessary in most cases with chronic symptoms or when conservative treatment fails in SMAS.Methods:A retrospective chart review was performed on patients who underwent operation for SMAS from January 2008 to August 2020 in Cardinal Tien Hospital. Patients’ clinical presentations, surgical intervention, and outcomes.Results:Data from a total of 14 patients diagnosed with SMAS were analyzed, of which seven were diagnosed with SMAS by abdominal computed tomography and upper gastrointestinal series with water-soluble barium contrast. Six of the confirmed cases underwent surgery, namely, gastric decompression using a nasogastric tube, andcorrection of electrolyte imbalance. The nasoduodenal tube was placed through the obstructed duodenum to provide a high-nutrient fluid supplement. After conservative treatment failure, the patients underwent surgery. Of the six patients, four underwent duodenojejunostomy, one underwent a mini-laparotomy duodenojejunostomy bypass, and the last one underwent Roux-en-Y duodenojejunal bypass with duodenal feeding tube insertion.Conclusion:Patients with SMAS should initially be treated conservative. Surgical intervention should be considered in patients in whom conservative treatments were not effective.Complete resolution of all symptoms may not always be guaranteed after surgical intervention. Laparoscopy is currently widely used. In well-selected patients, minimally invasive or mini-laparotomy duodenojejunostomy is a safe and effective treatment for SMAS. The main advantages of mini-laparotomy duodenojejunostomy over other surgical approaches include half-length surgical incision and a shorter operative time. Duodenojejunostomy is rapidly becoming the standard procedure of this condition, and it has excellent outcomes comparable with those of open surgery
Diffusion Model-Augmented Behavioral Cloning
Imitation learning addresses the challenge of learning by observing an
expert's demonstrations without access to reward signals from environments.
Most existing imitation learning methods that do not require interacting with
environments either model the expert distribution as the conditional
probability p(a|s) (e.g., behavioral cloning, BC) or the joint probability p(s,
a) (e.g., implicit behavioral cloning). Despite its simplicity, modeling the
conditional probability with BC usually struggles with generalization. While
modeling the joint probability can lead to improved generalization performance,
the inference procedure can be time-consuming and it often suffers from
manifold overfitting. This work proposes an imitation learning framework that
benefits from modeling both the conditional and joint probability of the expert
distribution. Our proposed diffusion model-augmented behavioral cloning (DBC)
employs a diffusion model trained to model expert behaviors and learns a policy
to optimize both the BC loss (conditional) and our proposed diffusion model
loss (joint). DBC outperforms baselines in various continuous control tasks in
navigation, robot arm manipulation, dexterous manipulation, and locomotion. We
design additional experiments to verify the limitations of modeling either the
conditional probability or the joint probability of the expert distribution as
well as compare different generative models
Dual-Octave Convolution for Accelerated Parallel MR Image Reconstruction
Magnetic resonance (MR) image acquisition is an inherently prolonged process,
whose acceleration by obtaining multiple undersampled images simultaneously
through parallel imaging has always been the subject of research. In this
paper, we propose the Dual-Octave Convolution (Dual-OctConv), which is capable
of learning multi-scale spatial-frequency features from both real and imaginary
components, for fast parallel MR image reconstruction. By reformulating the
complex operations using octave convolutions, our model shows a strong ability
to capture richer representations of MR images, while at the same time greatly
reducing the spatial redundancy. More specifically, the input feature maps and
convolutional kernels are first split into two components (i.e., real and
imaginary), which are then divided into four groups according to their spatial
frequencies. Then, our Dual-OctConv conducts intra-group information updating
and inter-group information exchange to aggregate the contextual information
across different groups. Our framework provides two appealing benefits: (i) it
encourages interactions between real and imaginary components at various
spatial frequencies to achieve richer representational capacity, and (ii) it
enlarges the receptive field by learning multiple spatial-frequency features of
both the real and imaginary components. We evaluate the performance of the
proposed model on the acceleration of multi-coil MR image reconstruction.
Extensive experiments are conducted on an {in vivo} knee dataset under
different undersampling patterns and acceleration factors. The experimental
results demonstrate the superiority of our model in accelerated parallel MR
image reconstruction. Our code is available at:
github.com/chunmeifeng/Dual-OctConv.Comment: Proceedings of the 35th AAAI Conference on Artificial Intelligence
(AAAI) 202
Meta-analysis of clinical randomized controlled trials comparing ReZOOM with ReSTOR multifocal intraocular lenses in cataract surgery
AIM: To systematic review the effectiveness of refractive multifocal intraocular lens(MIOL)ReZOOM <i>vs</i> diffractive MIOL ReSTOR in the treatment of cataract.<p>METHODS: Randomized controlled trials comparing refractive MIOL ReZOOM with diffractive MIOL ReSTOR were identified by searching CENTRAL, MEDLINE, EMbase, WANFANG MED ONLINE, CMJD, SinoMed, and CNKI. Related journals also were hand-searched. Methodological quality of randomized controlled trials(RCTs)was evaluated by simple evaluate method that recommended by the Cochrane Collaboration. Data extracted by two reviewers with designed extraction form. RevMan software(release 5.2)was used for data management and analysis.<p>RESULTS:A total of 7 trials(846 eyes)were included for systematic review. Subgroup analyses were used according to different model comparison of ReSTOR MIOL. The results showed a significant difference in the mean of the best distance corrected intermediate visual acuity(BDCIVA)in the ReZOOM MIOL group with WMD= -0.11, 95% <i>CI</i>(-0.16, -0.06)(<i>P</i><0.0001). It showed a significantly difference in the mean of the uncorrected near visual acuity(UCNVA), complete spectacle independent rate, halo rate and glare rate in the ReSTOR MIOL group with WMD= 0.09, 95% <i>CI</i>(0.05, 0.14)(<i>P</i><0.00001), WMD= 2.62, 95%<i>CI</i>(1.76, 3.91)(<i>P</i><0.00001), WMD=1.35, 95% <i>CI</i>(1.15, 1.60)(<i>P</i>=0.0004)and WMD= 1.29, 95% <i>CI</i>(1.09, 1.53)(<i>P</i>=0.003). There was no significant difference between the two groups in the mean of the uncorrected distance visual acuity(UCDVA), the uncorrected intermediate visual acuity(UCIVA), the best corrected distance visual acuity(BCDVA)and the best distance corrected near visual acuity(BDCNVA)with WMD -0.03, 95% <i>CI</i>(-0.06, 0.01)(<i>P</i>=0.15), WMD= -0.04, 95% <i>CI</i>(-0.09, 0.01)(<i>P</i>=0.10), WMD= -0.01, 95%<i>CI</i>(-0.04, 0.02)(<i>P</i>=0.55)and WMD= 0.06, 95% <i>CI</i>(-0.06, 0.17)(<i>P</i>=0.32). <p>CONCLUSION: Patients implanted with ReZOOM MIOL can provide better BDCIVA; patients implanted with ReSTOR MIOL show better UCNVA, are less likely to appear light halo, glare and other visual adverse reactions; correction in spectacles cases, patients implanted with ReZOOM or ReSTOR MIOL have considerable performances in the far and near visual acuity
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