154 research outputs found
STUDY ON KNEE JOINT ISOKINETIC STRENGTH OF MALE VOLLEYBALLPLAYERS
The purpose of this study is to measure the knee joint mechanics of eight elite volleyball players using isokinetic system and to discuss the possible diagnosis of injury risk of the results. Isokinetic-concentric contraction peak torque of the knee flexors and extensors decreased when angular velocity increased. With the same angular velocity, extension peak torque became higher than flexion peak torque. There was also a significant difference between the left and right knees in each flexion and extension peak torques. As the angular velocity increased, the flexion to extension peak torque ratios decreased; at the same time, average power increased while the work done decreased. The extensors showed greater work done than the flexors. The knee torque curves could be used as evidence for diagnosis of possible knee injury risks among volleyball players
Precoding and Beamforming Design for Intelligent Reconfigurable Surface-Aided Hybrid Secure Spatial Modulation
Intelligent reflecting surface (IRS) is an emerging technology for wireless
communication composed of a large number of low-cost passive devices with
reconfigurable parameters, which can reflect signals with a certain phase shift
and is capable of building programmable communication environment. In this
paper, to avoid the high hardware cost and energy consumption in spatial
modulation (SM), an IRS-aided hybrid secure SM (SSM) system with a hybrid
precoder is proposed. To improve the security performance, we formulate an
optimization problem to maximize the secrecy rate (SR) by jointly optimizing
the beamforming at IRS and hybrid precoding at the transmitter. Considering
that the SR has no closed form expression, an approximate SR (ASR) expression
is derived as the objective function. To improve the SR performance, three IRS
beamforming methods, called IRS alternating direction method of multipliers
(IRS-ADMM), IRS block coordinate ascend (IRS-BCA) and IRS semi-definite
relaxation (IRS-SDR), are proposed. As for the hybrid precoding design,
approximated secrecy rate-successive convex approximation (ASR-SCA) method and
cut-off rate-gradient ascend (COR-GA) method are proposed. Simulation results
demonstrate that the proposed IRS-SDR and IRS-ADMM beamformers harvest
substantial SR performance gains over IRS-BCA. Particularly, the proposed
IRS-ADMM and IRS-BCA are of low-complexity at the expense of a little
performance loss compared with IRS-SDR. For hybrid precoding, the proposed
ASR-SCA performs better than COR-GA in the high transmit power region.Comment: 14pages,8figure
Joint Optimization for RIS-Assisted Wireless Communications: From Physical and Electromagnetic Perspectives
Reconfigurable intelligent surfaces (RISs) are envisioned to be a disruptive
wireless communication technique that is capable of reconfiguring the wireless
propagation environment. In this paper, we study a free-space RIS-assisted
multiple-input single-output (MISO) communication system in far-field
operation. To maximize the received power from the physical and electromagnetic
nature point of view, a comprehensive optimization, including beamforming of
the transmitter, phase shifts of the RIS, orientation and position of the RIS
is formulated and addressed. After exploiting the property of line-of-sight
(LoS) links, we derive closed-form solutions of beamforming and phase shifts.
For the non-trivial RIS position optimization problem in arbitrary
three-dimensional space, a dimensional-reducing theory is proved. The
simulation results show that the proposed closed-form beamforming and phase
shifts approach the upper bound of the received power. The robustness of our
proposed solutions in terms of the perturbation is also verified. Moreover, the
RIS significantly enhances the performance of the mmWave/THz communication
system
Loss of the multifunctional RNA-binding protein RBM47 as a source of selectable metastatic traits in breast cancer.
The mechanisms through which cancer cells lock in altered transcriptional programs in support of metastasis remain largely unknown. Through integrative analysis of clinical breast cancer gene expression datasets, cell line models of breast cancer progression, and mutation data from cancer genome resequencing studies, we identified RNA binding motif protein 47 (RBM47) as a suppressor of breast cancer progression and metastasis. RBM47 inhibited breast cancer re-initiation and growth in experimental models. Transcriptome-wide HITS-CLIP analysis revealed widespread RBM47 binding to mRNAs, most prominently in introns and 3'UTRs. RBM47 altered splicing and abundance of a subset of its target mRNAs. Some of the mRNAs stabilized by RBM47, as exemplified by dickkopf WNT signaling pathway inhibitor 1, inhibit tumor progression downstream of RBM47. Our work identifies RBM47 as an RNA-binding protein that can suppress breast cancer progression and demonstrates how the inactivation of a broadly targeted RNA chaperone enables selection of a pro-metastatic state
UATVR: Uncertainty-Adaptive Text-Video Retrieval
With the explosive growth of web videos and emerging large-scale
vision-language pre-training models, e.g., CLIP, retrieving videos of interest
with text instructions has attracted increasing attention. A common practice is
to transfer text-video pairs to the same embedding space and craft cross-modal
interactions with certain entities in specific granularities for semantic
correspondence. Unfortunately, the intrinsic uncertainties of optimal entity
combinations in appropriate granularities for cross-modal queries are
understudied, which is especially critical for modalities with hierarchical
semantics, e.g., video, text, etc. In this paper, we propose an
Uncertainty-Adaptive Text-Video Retrieval approach, termed UATVR, which models
each look-up as a distribution matching procedure. Concretely, we add
additional learnable tokens in the encoders to adaptively aggregate
multi-grained semantics for flexible high-level reasoning. In the refined
embedding space, we represent text-video pairs as probabilistic distributions
where prototypes are sampled for matching evaluation. Comprehensive experiments
on four benchmarks justify the superiority of our UATVR, which achieves new
state-of-the-art results on MSR-VTT (50.8%), VATEX (64.5%), MSVD (49.7%), and
DiDeMo (45.8%). The code is available at https://github.com/bofang98/UATVR.Comment: To appear at ICCV202
- …