14,646 research outputs found
The distinctions between CDM and gravity according Noether symmetry
Noether's theory offers us a useful tool to research the conserved quantities
and symmetries of the modified gravity theories, among which the theory,
a generally modified teleparallel gravity, has been proposed to account for the
dark energy phenomena. By the Noether symmetry approach, we investigate the
power-law, exponential and polynomial forms of theories. All forms of
concerned in this work possess the time translational symmetry, which is
related with energy condition or Hamilton constraint. In addition, we find out
that the performances of the power-law and exponential forms are not pleasing.
It is rational adding a linear term to as the most efficient
amendment to resemble the teleparallel gravity or General Relativity on small
scales, ie., the scale of the solar system. The corresponding Noether symmetry
indicates that only time translational symmetry remains. Through numerically
calculations and observational data-sets constraining, the optimal form is obtained, whose cosmological solution resembles the
standard CDM best with lightly reduced cosmic age which can be
alleviated by introducing another term. More important is that we find
the significant differences between CDM and gravity. The
CDM model has also two additional symmetries and corresponding
positive conserved quantities, except the two negative conserved quantities.Comment: 9 pages, 5 figures, 2 tables, typos corrected, Refs. added, accepted
by EPJ-
Dual-view Curricular Optimal Transport for Cross-lingual Cross-modal Retrieval
Current research on cross-modal retrieval is mostly English-oriented, as the
availability of a large number of English-oriented human-labeled
vision-language corpora. In order to break the limit of non-English labeled
data, cross-lingual cross-modal retrieval (CCR) has attracted increasing
attention. Most CCR methods construct pseudo-parallel vision-language corpora
via Machine Translation (MT) to achieve cross-lingual transfer. However, the
translated sentences from MT are generally imperfect in describing the
corresponding visual contents. Improperly assuming the pseudo-parallel data are
correctly correlated will make the networks overfit to the noisy
correspondence. Therefore, we propose Dual-view Curricular Optimal Transport
(DCOT) to learn with noisy correspondence in CCR. In particular, we quantify
the confidence of the sample pair correlation with optimal transport theory
from both the cross-lingual and cross-modal views, and design dual-view
curriculum learning to dynamically model the transportation costs according to
the learning stage of the two views. Extensive experiments are conducted on two
multilingual image-text datasets and one video-text dataset, and the results
demonstrate the effectiveness and robustness of the proposed method. Besides,
our proposed method also shows a good expansibility to cross-lingual image-text
baselines and a decent generalization on out-of-domain data
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Hierarchical Structure with Highly Ordered Macroporous-Mesoporous Metal-Organic Frameworks as Dual Function for CO2 Fixation.
As a major greenhouse gas, the continuous increase of carbon dioxide (CO2) in the atmosphere has caused serious environmental problems, although CO2 is also an abundant, inexpensive, and nontoxic carbon source. Here, we use metal-organic framework (MOF) with highly ordered hierarchical structure as adsorbent and catalyst for chemical fixation of CO2 at atmospheric pressure, and the CO2 can be converted to the formate in excellent yields. Meanwhile, we have successfully integrated highly ordered macroporous and mesoporous structures into MOFs, and the macro-, meso-, and microporous structures have all been presented in one framework. Based on the unique hierarchical pores, high surface area (592 m2/g), and high CO2 adsorption capacity (49.51Â cm3/g), the ordered macroporous-mesoporous MOFs possess high activity for chemical fixation of CO2 (yield of 77%). These results provide a promising route of chemical CO2 fixation through MOF materials
Polysaccharides isolated from Morinda officinalis How roots inhibits cyclophosphamide-induced leukopenia in mice
Purpose: To investigate the optimum parameters for extracting polysaccharides from Morinda officinalis How (MOP), and explore their inhibitory effects on leukopenia in mice.Methods: Orthogonal design was performed to investigate the optimum parameters for extracting MOP. A leukopenia mouse model was established by injection of cyclophosphamide (CTX) for three days. Thereafter, MOP (100, 200 and 400 mg/kg) was administered orally for 10 days. Furthermore, blood cells (leukocytes, neutrophil, lymphocyte and mononuclear cell) were analyzed, while serum IL-3 and IL- 6 were determined by ELISA. The thymus and spleen of the mice were separated and weighed to determine viscera indices.Results: Orthogonal design showed that the influence order of the four factors was extraction times (C) > ratio of water to raw material (RWM, D) > extraction time (B) > extraction temperature (A). The optimum extraction parameters for MOP were: extraction temperature (80 °C), extraction duration (2 h), no. of extractions (3), and ratio of water to raw material (30 mL/g). Furthermore, the results indicate that MOP (100, 200 and 400 mg/kg) elevated the levels of leukocyte (p < 0.01), neutrophil (p < 0.01), lymphocyte (p < 0.01) and mononuclear cell (p < 0.01) in leukopenia mice. Besides, MOP (100, 200 and 400 mg/kg) also increased thymus (p < 0.01) and spleen (p < 0.05) indices and serum levels of IL-3 (p < 0.05) and IL-6 (p < 0.01).Conclusion: Orthogonal design is a good strategy for optimizing extraction parameters of MOP. Furthermore, MOP stimulated synthesis of leukocytes in CTX-induced leukopenia in mice. Thus, MOP is a potential adjunct for the treatment of tumors/cancers.Keywords: Morinda officinalis, Polyscacharide, Orthogonal design, Leukopenia, Thymus index, Spleen inde
The Effects of Qigong on Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis
Objective. The purpose of this study was to investigate the effects of Qigong on type 2 diabetes mellitus (DM) using the systematic review and meta-analysis. Methods. All prospective, randomized, controlled clinical trials published in English or Chinese and involving the use of Qigong by patients with DM were searched in 7 electronic databases from their respective inception to June 2016. The meta-analysis was conducted using the Revman 5.2. The quality of the included trials was assessed using the Jadad rating scale. Two researchers independently completed the inclusion, data extraction, and quality assessment. Results. Twenty-one trials with 1326 patients met the inclusion criteria and were reviewed. The meta-analysis demonstrated that, compared with no exercise, the Qigong had significant effects on fasting blood glucose (MD = −0.99, 95% CI (−1.23, 0.75), P<0.0001), HbA1c (MD = −0.84, 95% CI (−1.02, −0.65), P<0.0001), and postprandial blood glucose (MD = −1.55, 95% CI (−2.19, −0.91), P<0.00001). Conclusion. The Qigong training can improve the blood glucose status of the type 2 DM patients and has positive effects on the management of type 2 DM. However, future research with better quality still needs to be conducted to address the effects of Qigong on type 2 DM
Reduced glutamine synthetase activity alters the fecundity of female Bactrocera dorsalis (Hendel)
Glutamine synthetase (GS) is a key enzyme in glutamine synthesis and is associated with multiple physiological processes in insects, such as embryonic development, heat shock response, and fecundity regulation. However, little is known about the influence of GS on female fecundity in the oriental fruit fly, Bactrocera dorsalis. Based on the cloning of BdGSs, mitochondrial BdGSm and cytoplasmic BdGSc, we determined their expressions in the tissues of adult B. dorsalis. BdGSm was highly expressed in the fat body, while BdGSc was highly expressed in the head and midgut. Gene silencing by RNA interference against two BdGSs isoforms suppressed target gene expression at the transcriptional level, leading to a reduced ovarian size and lower egg production. The specific inhibitor L-methionine S-sulfoximine suppressed enzyme activity, but only the gene expression of BdGSm was suppressed. A similar phenotype of delayed ovarian development occurred in the inhibitor bioassay. Significantly lower expression of vitellogenin and vitellogenin receptor was observed when GS enzyme activity was suppressed. These data illustrate the effects of two GS genes on adult fecundity by regulating vitellogenin synthesis in different ways
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