372 research outputs found
Simplified TeV leptophilic dark matter in light of DAMPE data
Using a simplified framework, we attempt to explain the recent DAMPE cosmic
flux excess by leptophilic Dirac fermion dark matter (LDM). The
scalar () and vector () mediator fields connecting LDM and
Standard Model particles are discussed. Under constraints of DM relic density,
gamma-rays, cosmic-rays and Cosmic Microwave Background (CMB), we find that the
couplings , , and can
produce the right bump in flux for a DM mass around 1.5 TeV with a
natural thermal annihilation cross-section today. Among them, coupling is tightly constrained by
PandaX-II data (although LDM-nucleus scattering appears at one-loop level) and
the surviving samples appear in the resonant region, . We also study the related collider signatures, such as dilepton
production , and muon anomaly. Finally,
we present a possible realization for such leptophilic dark matter.Comment: discussions added, version accepted by JHE
Novel path curvature optimization algorithm for intelligent wheelchair to smoothly pass a narrow space
This paper presents a novel algorithm to address the smooth narrow pass traversing issue, which is based on optimizing the curvature of the wheelchair path. Being aware of the fact that the path smoothness is determined by the path curvature and its change rate, after calculating the position of the narrow pass relative to the base frame of the wheelchair from perception sensor data, the algorithm takes the curvature and its change rate of Bezier curve as the optimal objective, and the wheelchair heading and the condition that the Bezier curve polygon should be convex polygon as constraints, and plans a smooth and optimal path for the controlled wheelchair to follow. This process is iterated dynamically to enable the intelligent wheelchair to traverse the narrow pass smoothly. Simulation is firstly conducted to compare the performances of our method and the A*-based path planning navigation algorithm, which shows that the proposed algorithm is able to achieve more smooth path with smaller curvature when the wheelchair traverses narrow path. Furthermore, the algorithm can control the wheelchair to traverse narrow pass smoothly even without any global map and localization. Real experiment with detailed explanation of algorithm implementation is also given to verify the effectiveness of the proposed algorithm
Further discussion on soil and water conservation effect on water resources in the Yellow River Basin -TASAE, 2004 Further discussion on the effect of soil and water conservation on water resources in the Yellow River Basin
In the last half century, because of climate change and large scale human activities, such as water resources engineering, water use of industry, agriculture, and soil and water conservation practices (SWCP), the water resource problems in the Yellow River Basin (YRB) have become more obvious. As a result of sediment erosion control, runoff has decreased in the YRB, and therefore its impact on water resources has become an issue of great concerned. Cui (2002) blamed rainfall reduction and SWCP for cutting-off of flowing to the sea. Chen Characteristics and problems of water resources in the YRB The amount and per capita volume of water resources are both very low. The lack of water resource in the YRB in the last fifty years is not only because the water resources distribution is not temporally and spatially even
AutoDiffusion: Training-Free Optimization of Time Steps and Architectures for Automated Diffusion Model Acceleration
Diffusion models are emerging expressive generative models, in which a large
number of time steps (inference steps) are required for a single image
generation. To accelerate such tedious process, reducing steps uniformly is
considered as an undisputed principle of diffusion models. We consider that
such a uniform assumption is not the optimal solution in practice; i.e., we can
find different optimal time steps for different models. Therefore, we propose
to search the optimal time steps sequence and compressed model architecture in
a unified framework to achieve effective image generation for diffusion models
without any further training. Specifically, we first design a unified search
space that consists of all possible time steps and various architectures. Then,
a two stage evolutionary algorithm is introduced to find the optimal solution
in the designed search space. To further accelerate the search process, we
employ FID score between generated and real samples to estimate the performance
of the sampled examples. As a result, the proposed method is (i).training-free,
obtaining the optimal time steps and model architecture without any training
process; (ii). orthogonal to most advanced diffusion samplers and can be
integrated to gain better sample quality. (iii). generalized, where the
searched time steps and architectures can be directly applied on different
diffusion models with the same guidance scale. Experimental results show that
our method achieves excellent performance by using only a few time steps, e.g.
17.86 FID score on ImageNet 64 64 with only four steps, compared to
138.66 with DDIM. The code is available at
https://github.com/lilijiangg/AutoDiffusion
Mitigation of chronic unpredictable stress–induced cognitive deficits in mice by Lycium barbarum L (Solanaceae) polysaccharides
Purpose: To investigate the neuroprotective effects of Lycium barbarum polysaccharide (LBP) against concomitant cognitive dysfunction and changes in hippocampal CREB-BDNF signaling pathway in chronically unpredictable stressed mice.Methods: The mice were subjected to different unpredictable stressors for a period of 4 weeks. Behavioral tests, including open field (OFT) and Morris water maze (MWMT) tests were used to evaluate pharmacological effects. Serum corticosterone levels, protein expression level of BDNF and pCREB/CREB in hippocampus were assessed by ELISA, Western blot and immunohistochemistry methods, respectively. Morphological changes in pyramidal neurons in the hippocampus were studied by Nissl staining.Results: LBP improved mice performance in MWMT, indicating that it reversed chronic unpredictable stress (CUS)-induced cognitive deficits. LBP treatment reduced serum corticosterone levels and prevented neuron loss in the hippocampus. It maintained expression levels of BDNF and phosphorylation of CREB in hippocampus during CUS procedure.Conclusion: Lycium barbarum polysaccharide protects CREB-BDNF signaling pathway in hippocampus and relieves CUS-induced cognitive deficits. These results suggest that Lycium barbarum polysaccharides is potentially an alternative neuro-protective agent against stress-induced psychopathological dysfunction.Keywords: Lycium barbarum, Polysaccharide, Chronic unpredictable stress, Cognitive deficits, Brainderived neurotrophic factor, Calcium/cyclic-AMP responsive binding protei
Parent artery reconstruction for large or giant cerebral aneurysms using a Tubridge flow diverter (PARAT): study protocol for a multicenter, randomized, controlled clinical trial
BACKGROUND: The treatment of large (10-25 mm) or giant (≥25 mm) cerebral aneurysms remains technically challenging, with a much higher complication and recanalization rate than that is observed for smaller aneurysms. The use of a flow diverter seems to facilitate the treatment of this special entity. In a previous single-center prospective study approved by the Ethics Committee and China Food and Drug Administration (CFDA), we obtained promising results, showing remarkable safety and effectiveness for the Tubridge flow diverter. Nevertheless, the previous study may have been limited by biases due to its single-center design and limited number of subjects. Furthermore, although various articles have reported durable results from treating aneurysms using flow diverters, increasing questions have arisen about this form of treatment. Thus, prospective, multiple-center, randomized trials containing more subjects are needed. METHODS/DESIGN: This study is a multicenter, randomized, controlled clinical trial comparing clinical outcomes for patients with unruptured large/giant intracranial aneurysms treated with either conventional stent-assisted coiling or flow diverter implantation. A total of 124 patients who fulfill the inclusion and exclusion criteria will be randomized into either a treatment group or a control group in the ratio of 1:1. The treatment group will receive Tubridge implantation alone or combined with bared coils, and the control group will be treated with stent-assisted coiling (bare coils). The primary endpoint will be the complete occlusion rate at 6-month follow-up. Secondary endpoints include the immediate technique success rate, overall mortality, adverse events (ischemic stroke or intracranial bleeding) within 30 days, 90 days and 1 year post-operation, and the rate of intra-stent stenosis and thrombosis 6 months post-operation. DISCUSSION: This prospective trial may provide more information on the safety and efficacy of the Tubridge flow diverter and may potentially change the strategy for treatment of large or giant aneurysms. TRIAL REGISTRATION: The trial is registered on the Chinese Clinical Trial Registry: ChiCTR-TRC-1300312
A Covalently Imprinted Photonic Crystal for Glucose Sensing
We demonstrate a glucose-sensing material based on the combination of photonic crystal templating and a molecular-imprinting technique. In the presence of the target molecule glucose, poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) hydrogel with pendent phenylboronic acid groups was synthesized in the void of a poly(methyl methacrylate) (PMMA) colloidal crystal. After removing the PMMA photonic crystal template and glucose molecules, a 3D-ordered porous covalently imprinted photonic crystal (CIPC) hydrogel was created. The unique 3D-ordered porous hydrogel revealed optical changes in response to glucose concentration. At pH = 11 and 37∘C, the diffraction of CIPC redshifted from 725 nm to 880 nm in response to 20 mmol L−1 glucose. Due to the covalently imprinted recognizer, boronic acid group, the selectivity of the CIPC towards glucose over D-ribose and L-rhamnose was improved significantly
The Interaction between Stent(s) Implantation, PICA Involvement, and Immediate Occlusion Degree Affect Symptomatic Intracranial Spontaneous Vertebral Artery Dissection Aneurysm (sis-VADA) Recurrence after Reconstructive Treatment with Stent(s)-Assisted Coiling
OBJECTIVES: We aimed to evaluate risk factors of sis-VADAs recurrence after reconstructive treatment based on 113 reconstructed lesions. METHODS: A total of 111 patients (M:F = 68:43; median age, 47 years) with 113 sis-VADAs underwent reconstruction from October 2000 to March 2011, using stent(s) and coils. Treatments and predictors of recurrence were retrospectively analysed. RESULTS: Fifty-eight sis-VADAs underwent single-stent treatment, and the remaining 55 sis-VADAs underwent treatment with 2-4 overlapping stents. Follow-up angiography was available for 94 sis-VADAs 12 -78 months, with recurrence in ten patients, including seven angiographic recurrences and three post-treatment haemorrhagic recurrences. A higher rate of post-treatment recurrence was observed in the single stent group than in the multiple stents group (p = 0.010). The interaction between stent (s) implantation and immediate occlusion degree (odds ratio [OR] =3.152; 95 % confidence interval [CI], 1.293-7.686; p = 0.012), between stent (s) implantation and the posterior inferior cerebellar artery (PICA) involvement (OR = 4.607; 95 % CI, 1.172-18.113; p = 0.029), and between PICA involvement and immediate occlusion degree (OR = 5.018; 95 % CI, 1.263-19.933; p = 0.022) affect recurrence in the reconstructed sis-VADAs. CONCLUSIONS: This single centre cohort study indicated that the interaction effect between stent (s) implantation, PICA involvement, and immediate occlusion degree were closely associated with recurrence after reconstructive treatment of sis-VADA. KEY POINTS: • The interaction between stent (s) and immediate occlusion degree affect aneurysmal recurrence • The interaction between stent and PICA involvement affect aneurysmal recurrence • The interaction between PICA involvement and immediate occlusion degree affect aneurysmal recurrence ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00330-014-3225-7) contains supplementary material, which is available to authorized users
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