6,607 research outputs found
Limitations of Absolute Current Densities Derived from the Semel & Skumanich Method
Semel and Skumanich proposed a method to obtain the absolute electric current
density, |Jz|, without disambiguation of 180 degree in the transverse field
directions. The advantage of the method is that the uncertainty in the
determination of the ambiguity in the magnetic azimuth is removed. Here, we
investigate the limits of the calculation when applied to a numerical MHD
model. We found that the combination of changes in the magnetic azimuth with
vanishing horizontal field component leads to errors, where electric current
densities are often strong. Where errors occur, the calculation gives |Jz| too
small by factors typically 1.2 ~ 2.0.Comment: 10 pages, 4 figures. To appear on Science in China Series G: Physics,
Mechanics & Astronomy, October 200
The Impact of Organizational Coordination and Climate on Marketing Executives\u27 Satisfaction with Information Systems Services
Information system (IS) managers rely on a number of devices to improve performance and the perception of performance on the part of the user. These techniques can be a variety of tools and organizational structures put in place by various levels of management. Horizontal coordination activities are such a device, one that is intended to improve the communication between users and IS developers. Past research has found an impact of coordination on IS success. However, the climate, general attitudes about the IS function in an organization in which the developers and users operate, can serve as an important moderator. Analysis of a sample of marketing executives indicates that the climate is an important moderator and may impact the ability of structural features to improve perceived performance. Managers must consider the climate as an important feature
SwinCross: Cross-modal Swin Transformer for Head-and-Neck Tumor Segmentation in PET/CT Images
Radiotherapy (RT) combined with cetuximab is the standard treatment for
patients with inoperable head and neck cancers. Segmentation of head and neck
(H&N) tumors is a prerequisite for radiotherapy planning but a time-consuming
process. In recent years, deep convolutional neural networks have become the de
facto standard for automated image segmentation. However, due to the expensive
computational cost associated with enlarging the field of view in DCNNs, their
ability to model long-range dependency is still limited, and this can result in
sub-optimal segmentation performance for objects with background context
spanning over long distances. On the other hand, Transformer models have
demonstrated excellent capabilities in capturing such long-range information in
several semantic segmentation tasks performed on medical images. Inspired by
the recent success of Vision Transformers and advances in multi-modal image
analysis, we propose a novel segmentation model, debuted, Cross-Modal Swin
Transformer (SwinCross), with cross-modal attention (CMA) module to incorporate
cross-modal feature extraction at multiple resolutions.To validate the
effectiveness of the proposed method, we performed experiments on the HECKTOR
2021 challenge dataset and compared it with the nnU-Net (the backbone of the
top-5 methods in HECKTOR 2021) and other state-of-the-art transformer-based
methods such as UNETR, and Swin UNETR. The proposed method is experimentally
shown to outperform these comparing methods thanks to the ability of the CMA
module to capture better inter-modality complimentary feature representations
between PET and CT, for the task of head-and-neck tumor segmentation.Comment: 9 pages, 3 figures. Med Phys. 202
On reducing mesh delay for peer-to-peer live streaming
Peer-to-peer (P2P) technology has emerged as a promising scalable solution for live streaming to large group. In this paper, we address the design of overlay which achieves low source-to-peer delay, is robust to user churn, accommodates of asymmetric and diverse uplink bandwidth, and continuously improves based on existing user pool. A natural choice is the use of mesh, where each peer is served by multiple parents. Since the peer delay in a mesh depends on its longest path through its parents, we study how to optimize such delay while meeting a certain streaming rate requirement. We first formulate the minimum delay mesh problem and show that it is NP-hard. Then we propose a centralized heuristic based on complete knowledge which serves as our benchmark and optimal solution for all the other schemes under comparison. Our heuristic makes use of the concept of power in network given by the ratio of throughput and delay. By maximizing the network power, our heuristic achieves very low delay. We then propose a simple distributed algorithm where peers select their parents based on the power concept. The algorithm makes continuous improvement on delay until some minimum delay is reached. Simulation results show that our distributed protocol performs close to the centralized one, and substantially outperforms traditional and state-of-the-art approaches
Myricetin inhibits proliferation of cisplatin-resistant cancer cells through a p53-dependent apoptotic pathway
Cisplatin is a commonly used drug for cancer treatment by crosslinking DNA, leading to apoptosis of cancer cells, resistance to cisplatin treatment often occurs, leading to relapse. Therefore, there is a need for the development of more effective treatment strategies that can overcome chemoresistance. Myricetin is a flavonoid from fruits and vegetables, showing anticancer activity in various cancer cells. In this study, we found myricetin exhibited greater cytotoxicity than cisplatin in two cisplatin-resistant ovarian cancer cell lines, OVCAR-3 and A2780/CP70, and it was less cytotoxic to the normal ovarian cell line IOSE-364. Myricetin selectively induced apoptosis in both cisplatin-resistant cancer cell lines, but did not induce apoptosis in the normal ovarian cell line. It induced both Bcl-2 family-dependent intrinsic and DR5 dependent extrinsic apoptosis in OVCAR-3 cells. P53, a multifunctional tumor suppressor, regulated apoptosis in OVCAR-3 cells through a Bcl-2 family protein-dependent pathway. Myricetin did not induce cell cycle arrest in either ovarian cancer cell line. Because of its potency and selectivity against cisplatin-resistant cancer cells, myricetin could potentially be used to overcome cancer chemoresistance against platinum-based therapy
Myricetin inhibits proliferation of cisplatin-resistant cancer cells through a p53-dependent apoptotic pathway
Cisplatin is a commonly used drug for cancer treatment by crosslinking DNA, leading to apoptosis of cancer cells, resistance to cisplatin treatment often occurs, leading to relapse. Therefore, there is a need for the development of more effective treatment strategies that can overcome chemoresistance. Myricetin is a flavonoid from fruits and vegetables, showing anticancer activity in various cancer cells. In this study, we found myricetin exhibited greater cytotoxicity than cisplatin in two cisplatin-resistant ovarian cancer cell lines, OVCAR-3 and A2780/CP70, and it was less cytotoxic to the normal ovarian cell line IOSE-364. Myricetin selectively induced apoptosis in both cisplatinresistant cancer cell lines, but did not induce apoptosis in the normal ovarian cell line. It induced both Bcl-2 familydependent intrinsic and DR5 dependent extrinsic apoptosis in OVCAR-3 cells. P53, a multifunctional tumor suppressor, regulated apoptosis in OVCAR-3 cells through a Bcl-2 family protein-dependent pathway. Myricetin did not induce cell cycle arrest in either ovarian cancer cell line. Because of its potency and selectivity against cisplatin-resistant cancer cells, myricetin could potentially be used to overcome cancer chemoresistance against platinum-based therapy
Fate of the Black String Instability
Gregory and Laflamme showed that certain nonextremal black strings (and
p-branes) are unstable to linearized perturbations. It is widely believed that
this instability will cause the black string horizon to classically pinch off
and then quantum mechanically separate, resulting in higher dimensional black
holes. We argue that this cannot happen. Under very mild assumptions, classical
event horizons cannot pinch off. Instead, they settle down to new static black
string solutions which are not translationally invariant along the string.Comment: 11 pages, v2: few clarifications and references adde
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