143 research outputs found
Modeling Social Media User Content Generation Using Interpretable Point Process Models
In this article, we study the activity patterns of modern social media users
on platforms such as Twitter and Facebook. To characterize the complex patterns
we observe in users' interactions with social media, we describe a new class of
point process models. The components in the model have straightforward
interpretations and can thus provide meaningful insights into user activity
patterns. A composite likelihood approach and a composite EM estimation
procedure are developed to overcome the challenges that arise in parameter
estimation. Using the proposed method, we analyze Donald Trump's Twitter data
and study if and how his tweeting behavior evolved before, during and after the
presidential campaign. Additionally, we analyze a large-scale social media data
from Sina Weibo and identify interesting groups of users with distinct
behaviors; in this analysis, we also discuss the effect of social ties on a
user's online content generating behavior
catena-Poly[[[aqua(7-hydroxy-2H-1-benzopyran-2-one)sodium]-di-μ-aqua] 2-oxo-2H-1-benzopyran-7-olate monohydrate]
The asymmetric unit of the title compound, {[Na(C9H6O3)(H2O)3](C9H5O3)·H2O}n, contains two crystallographically independent Na atoms, two 7-hyÂdroxyÂcoumarin ligands, six coordinated water molÂecules, two 7-hyÂdroxyÂcoumarin anions and two uncoordinated water molÂecules. Both Na atoms exhibit a distorted octaÂhedral coordination geometry and are coordinated by five water O atoms and the terminal O atom from a 7-hyÂdroxyÂcoumarin ligand. Four of the water molÂecules are bridging, whereas the fifth is terminal. Na—O bond distances are in the range 2.288 (2)–2.539 (2) Å. In the chains, extending parallel to [100], adjacent Na atoms are separated by 3.60613 (7) Å. The uncoordinated water molÂecules and 7-hyÂdroxyÂcoumarin phenolate anions are located between the chains and are hydrogen bonded to the chains
Identifying and decoupling many-body interactions in spin ensembles in diamond
We simulate the dynamics of varying density quasi-two-dimensional spin
ensembles in solid-state systems, focusing on the nitrogen-vacancy centers in
diamond. We consider the effects of various control sequences on the averaged
dynamics of large ensembles of spins, under a realistic "spin-bath"
environment. We reveal that spin locking is efficient for decoupling spins
initialized along the driving axis, both from coherent dipolar interactions and
from the external spin-bath environment, when the driving is two orders of
magnitude stronger than the relevant coupling energies. Since the application
of standard pulsed dynamical decoupling sequences leads to strong decoupling
from the environment, while other specialized pulse sequences can decouple
coherent dipolar interactions, such sequences can be used to identify the
dominant interaction type. Moreover, a proper combination of pulsed decoupling
sequences could lead to the suppression of both interaction types, allowing
additional spin manipulations. Finally, we consider the effect of finite-width
pulses on these control protocols and identify improved decoupling efficiency
with increased pulse duration, resulting from the interplay of dephasing and
coherent dynamics
Design, Synthesis, and Pharmacological Evaluation of Haloperidol Derivatives as Novel Potent Calcium Channel Blockers with Vasodilator Activity
Several haloperidol derivatives with a piperidine scaffold that was decorated at the nitrogen atom with different alkyl, benzyl, or substituted benzyl moieties were synthesized at our laboratory to establish a library of compounds with vasodilator activity. Compounds were screened for vasodilatory activity on isolated thoracic aorta rings from rats, and their quantitative structure–activity relationships (QSAR) were examined. Based on the result of QSAR, N-4-tert-butyl benzyl haloperidol chloride (16c) was synthesized and showed the most potent vasodilatory activity of all designed compounds. 16c dose-dependently inhibited the contraction caused by the influx of extracellular Ca2+ in isolated thoracic aorta rings from rats. It concentration-dependently attenuated the calcium channel current and extracellular Ca2+ influx, without affecting the intracellular Ca2+ mobilization, in vascular smooth muscle cells from rats. 16c, possessing the N-4-tert-butyl benzyl piperidine structure, as a novel calcium antagonist, may be effective as a calcium channel blocker in cardiovascular disease
Effect of geotextile sewing method on dewatering performance of geotubes: an experimental study
Geotubes are made by sewing geotextiles together and geotextiles are woven with warp and weft threads of different mechanical properties. This research explores effect of geotextile sewing method on dewatering performance of geotubes using a hanging bag test. Two types of hanging bags are made by different geotextile sewing methods: horizontal bag with the warp threads along its circular direction and vertical bag with the warp threads along its axial direction. The test results show that the dewatering performance of the bag is better if its weft stress is greater than warp stress. Combined with the stress analysis of a simplified geotube, the effect of geotextile sewing method on dewatering performance of geotubes is obtained: when the circumferential direction of geotubes is consistent with the weft threads, dewatering performance of geotubes will be better. This finding has the potential to act as a guideline for construction of geotubes in engineering
Comparison of PET/CT and MRI in the Diagnosis of Bone Metastasis in Prostate Cancer Patients: A Network Analysis of Diagnostic Studies
Background: Accurate diagnosis of bone metastasis status of prostate cancer (PCa) is becoming increasingly more important in guiding local and systemic treatment. Positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) have increasingly been utilized globally to assess the bone metastases in PCa. Our meta-analysis was a high-volume series in which the utility of PET/CT with different radioligands was compared to MRI with different parameters in this setting.
Materials and Methods: Three databases, including Medline, Embase, and Cochrane Library, were searched to retrieve original trials from their inception to August 31, 2019 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. The methodological quality of the included studies was assessed by two independent investigators utilizing Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). A Bayesian network meta-analysis was performed using an arm-based model. Absolute sensitivity and specificity, relative sensitivity and specificity, diagnostic odds ratio (DOR), and superiority index, and their associated 95% confidence intervals (CI) were used to assess the diagnostic value.
Results: Forty-five studies with 2,843 patients and 4,263 lesions were identified. Network meta-analysis reveals that 68Ga-labeled prostate membrane antigen (68Ga-PSMA) PET/CT has the highest superiority index (7.30) with the sensitivity of 0.91 and specificity of 0.99, followed by 18F-NaF, 11C-choline, 18F-choline, 18F-fludeoxyglucose (FDG), and 18F-fluciclovine PET/CT. The use of high magnetic field strength, multisequence, diffusion-weighted imaging (DWI), and more imaging planes will increase the diagnostic value of MRI for the detection of bone metastasis in prostate cancer patients. Where available, 3.0-T high-quality MRI approaches 68Ga-PSMA PET/CT was performed in the detection of bone metastasis on patient-based level (sensitivity, 0.94 vs. 0.91; specificity, 0.94 vs. 0.96; superiority index, 4.43 vs. 4.56).
Conclusions: 68Ga-PSMA PET/CT is recommended for the diagnosis of bone metastasis in prostate cancer patients. Where available, 3.0-T high-quality MRI approaches 68Ga-PSMA PET/CT should be performed in the detection of bone metastasis
β-Arrestin2 Inhibits Expression of Inflammatory Cytokines in BEAS-2B Lung Epithelial Cells Treated with Cigarette Smoke Condensate via Inhibition of Autophagy
Background/Aims: β-arrestin2 has been shown to have a role in human inflammatory disease. However, the role of β-arrestin2 in cigarette smoke-induced inflammation in the lung remains unknown. The aims of this study were to investigate the effects of β-arrestin2 on cigarette smoke condensate (CSC)-induced expression of inflammatory cytokines in the BEAS-2B human bronchial epithelial cell line in vitro, and the mechanisms involved. Methods: The MTT assay determined cell viability of cultured BEAS-2B cells. Autophagy was assessed by western blot, adenoviral mRFP-GFP-LC3 transfection, and immunofluorescence. The effects of β-arrestin2 shRNA knockdown were studied by western blot and real-time reverse transcription-polymerase chain reaction (RT-PCR). Western blot evaluated the AMPK/mTOR signaling pathway. Levels of inflammatory cytokines, interleukin (IL)-6, IL-8, and MCP-1 were measured in cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). Results: CSC suppressed expression of β-arrestin2 in BEAS-2B cells, activated the AMPK/mTOR signaling pathway, increased cell autophagy and the expression of IL-6, IL-8, and MCP-1,pretreatment with the β-arrestin2 biased ligands, propranolol, and ICI118551 reversed these changes. Inhibition of autophagy reduced the expression of inflammatory cytokines following CSC. Conclusion: In the human bronchial epithelial cell line, BEAS-2B, β-arrestin2 reduced the expression of CSC-induced inflammatory cytokines by inhibiting autophagy, most likely via the AMPK/mTOR signaling pathway
Six underutilized grain crops for food and nutrition in China
Underutilized grain crops are an essential part of the food system that supports humankind. A number of these crops can be found in China, such as barley, buckwheat, broomcorn millet, foxtail millet, oat, and sorghum, which have characteristics such as containing more nutritional elements, being resistant to biotic and abiotic stresses, and having strong adaptability to poor environments. The diversity of these crops provides options for farmers’ livelihoods and healthy food for the population. Although some mentioned crops such as barley, oat, and sorghum are not underutilized crops globally, they could be considered underutilized in China as they were more important in the past and could be revitalized for food and nutrition in the future. This paper reviews current progress in research and development in the areas of germplasm resource conservation, variety improvement, cultivation technologies, processing, and the nutrition and benefits of six underutilized grain crops in China. It is concluded that underutilized grain crops could play a critical role in food and nutritional security in China
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