1,080 research outputs found
Volatility and diversification of exports: firm level theory and evidence
We show using detailed firm-level Chinese data that, among small exporters, firms selling to a more diversified set of countries have more volatile exports, while the opposite holds among large exporters. This apriori surprising result for small firms is robust to a wide array of specifications and controls. Our theoretical explanation for these observations rests on the presence of fixed costs of exports per destination and short run demand shocks. In this setup , the volatility of a firm's exports depends not only on the diversification of its destination portfolio but also on whether it exports permanently to all markets. Among all exporters, a more diversified pool of destinations makes the firm more likely to export occasionally to some markets, thereby raising export volatility
Volatility and diversification of exports: Firm-level theory and evidence:Firm-level theory and evidence
We show using detailed firm-level Chinese data that, among small exporters, firms selling to a more diversified set of countries have more volatile exports, while the opposite holds among large exporters. This a priori surprising result for small firms is robust to a wide array of specifications and controls. Our theoretical explanation for these observations rests on the presence of fixed costs of exports per destination and short-run demand shocks. In this setup, the volatility of a firm's exports depends not only on the diversification of its destination portfolio but also on whether it exports permanently to all markets. Among small exporters, a more diversified pool of destinations makes the firm more likely to export occasionally to some markets, thereby raising export volatility
Gene Transfer of Calcitonin Gene-Related Peptide Inhibits Macrophages and Inflammatory Mediators in Vein Graft Disease
Vein graft disease is a chronic inflammatory disease and limits the late results of coronary revascularization. Calcitonin gene-related peptide (CGRP) inhibits macrophages infiltrated and inflammatory mediators, we hypothesized that transfected CGRP gene inhibits macrophages infiltrated and inflammatory mediators in vein graft disease. Autologous rabbit jugular vein grafts were incubated ex vivo in a solution of mosaic adeno-associated virus vectors containing CGRP gene (AAV2/1.CGRP) 、escherichia coli lac Z gene (AAV2/1.LacZ) or saline and then interposed in the carotid artery. Intima/media ratio were evaluated at postoperative 4 weeks, Macrophages were marked with CD68 antibody by immunocytochemistry. Inflammatory mediators were mensurated with real-time PCR. Neointimal thickening was significantly suppressed in AAV2/1.CGRP group. Macrophages infiltrated and inflammatory mediators monocyte chemoattractant protein-1 (MCP-1)、tumor necrosis factorα(TNF-α)、inducible nitricoxide synthase (iNOS)、matrix metalloproteinase-9 (MMP-9) was significantly suppressed in AAV2/1.CGRP group.Gene transfected AAV2/1.CGRP suppressed neointimal hyperplasia in vein graft disease by suppressed macrophages infiltrated and inflammatory mediators
APETALA2 antagonizes the transcriptional activity of AGAMOUS in regulating floral stem cells in Arabidopsis thaliana.
APETALA2 (AP2) is best known for its function in the outer two floral whorls, where it specifies the identities of sepals and petals by restricting the expression of AGAMOUS (AG) to the inner two whorls in Arabidopsis thaliana. Here, we describe a role of AP2 in promoting the maintenance of floral stem cell fate, not by repressing AG transcription, but by antagonizing AG activity in the center of the flower. We performed a genetic screen with ag-10 plants, which exhibit a weak floral determinacy defect, and isolated a mutant with a strong floral determinacy defect. This mutant was found to harbor another mutation in AG and was named ag-11. We performed a genetic screen in the ag-11 background to isolate mutations that suppress the floral determinacy defect. Two suppressor mutants were found to harbor mutations in AP2. While AG is known to shut down the expression of the stem cell maintenance gene WUSCHEL (WUS) to terminate floral stem cell fate, AP2 promotes the expression of WUS. AP2 does not repress the transcription of AG in the inner two whorls, but instead counteracts AG activity
Prognostic nomogram for bladder cancer with brain metastases: a National Cancer Database analysis.
BACKGROUND: This study aimed to establish and validate a nomogram for predicting brain metastasis in patients with bladder cancer (BCa) and assess various treatment modalities using a primary cohort comprising 234 patients with clinicopathologically-confirmed BCa from 2004 to 2015 in the National Cancer Database.
METHODS: Machine learning method and Cox model were used for nomogram construction. For BCa patients with brain metastasis, surgery of the primary site, chemotherapy, radiation therapy, palliative care, brain confinement of metastatic sites, and the Charlson/Deyo Score were predictive features identified for building the nomogram.
RESULTS: For the original 169 patients considered in the model, the areas under the receiver operating characteristic curve (AUC) were 0.823 (95% CI 0.758-0.889, P \u3c 0.001) and 0.854 (95% CI 0.785-0.924, P \u3c 0.001) for 0.5- and 1-year overall survival respectively. In the validation cohort, the nomogram displayed similar AUCs of 0.838 (95% CI 0.738-0.937, P \u3c 0.001) and 0.809 (95% CI 0.680-0.939, P \u3c 0.001), respectively. The high and low risk groups had median survivals of 1.91 and 5.09 months for the training cohort and 1.68 and 8.05 months for the validation set, respectively (both P \u3c 0.0001).
CONCLUSIONS: Our prognostic nomogram provides a useful tool for overall survival prediction as well as assessing the risk and optimal treatment for BCa patients with brain metastasis
Numerical model for geothermal energy utilization from double pipe heat exchanger in abandoned oil wells
The number of abandonded wells are increasing in the late period of oilfield development. The utilization of these abandonded oil wells is promising and environment-friendly for geothermal development. In this study, a numerical model for geothermal heating is derived from a double pipe heat exchanger in abandoned oil wells. The main influencing factors of injection rate, injection time, and the types of filler in casing annulus on temperature profiles and outlet temperature have been considered in this model. The influences of injection rate on heat-mining rate are then discussed. Results show that the double pipe heat exchanger can gain higher temperature at the outlet when the casing annulus is filled by liquid other than dry cement under the given parameter combination. The outlet temperature decreases with the increase in injection rate and injection time. The temperature rapidly decreases in the first 40 days during the injection process. The balance between heat mining rate and outlet temperature is important for evaluating a double pipe heat exchanger in abandoned oil wells. This work may provide a useful tool for a field engineer to estimate the temperature of liquid in wellhead and evaluate the heat transfer efficiency for double pipe heat exchanger in abandoned oil wells.Cited as: Lin, Z., Liu, K., Liu, J., Geng, D., Ren, K., Zheng, Z. Numerical model for geothermal energy utilization from double pipe heat exchanger in abandoned oil wells. Advances in Geo-Energy Research, 2021, 5(2): 212-221, doi: 10.46690/ager.2021.02.1
Experimental demonstration of an integrated on-chip p-bit core utilizing stochastic Magnetic Tunnel Junctions and 2D-MoS FETs
Probabilistic computing is a novel computing scheme that offers a more
efficient approach than conventional CMOS-based logic in a variety of
applications ranging from optimization to Bayesian inference, and invertible
Boolean logic. The probabilistic-bit (or p-bit, the base unit of probabilistic
computing) is a naturally fluctuating entity that requires tunable
stochasticity; by coupling low-barrier stochastic Magnetic Tunnel Junctions
(MTJs) with a transistor circuit, a compact implementation is achieved. In this
work, through integrating stochastic MTJs with 2D-MoS FETs, the first
on-chip realization of a key p-bit building block displaying
voltage-controllable stochasticity is demonstrated. In addition, supported by
circuit simulations, this work provides a careful analysis of the three
transistor-one magnetic tunnel junction (3T-1MTJ) p-bit design, evaluating how
the characteristics of each component influence the overall p-bit output. This
understanding of the interplay between the characteristics of the transistors
and the MTJ is vital for the construction of a fully functioning p-bit, making
the design rules presented in this article key for future experimental
implementations of scaled on-chip p-bit networks
catena-Poly[[[aqua(1,10-phenanthroline)cadmium(II)]-μ-benzene-1,4-dicarboxylato] benzene-1,4-dicarboxylic acid hemisolvate]
A new cadmium(II) coordination polymer, {[Cd(C8H4O4)(C12H8N2)(H2O)]·0.5C8H6O4}n, has been synthesized under hydrothermal conditions. The asymmetric unit contains one CdII atom, one benzene-1,4-dicarboxylate anion, one 1,10-phenanthroline ligand, one coordinated water molecule and half of an uncoordinated benzene-1,4-dicaboxylic acid solvent molecule. The CdII atom is in the centre of a monocapped distorted octahedron made up of four O atoms of two chelating benzene-1,4-dicarboxylate anions, one water O atom and two 1,10-phenanthroline N atoms. The metal centres are connected via bis-chelating benzene-1,4-dicarboxylate anions into a zigzag chain structure along [001]. These chains are further connected by O—H⋯O hydrogen bonds between the water molecules and adjacent carboxylate O atoms. Additional O—H⋯O hydrogen bonding between the uncoordinated benzene-1,4-dicaboxylic acid molecules along [010] consolidates the structure
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