93 research outputs found
Dynamic Flow-Adaptive Spectrum Leasing with Channel Aggregation in Cognitive Radio Networks
Cognitive radio networks (CRNs), which allow secondary users (SUs) to dynamically access a network without affecting the primary users (PUs), have been widely regarded as an effective approach to mitigate the shortage of spectrum resources and the inefficiency of spectrum utilization. However, the SUs suffer from frequent spectrum handoffs and transmission limitations. In this paper, considering the quality of service (QoS) requirements of PUs and SUs, we propose a novel dynamic flow-adaptive spectrum leasing with channel aggregation. Specifically, we design an adaptive leasing algorithm, which adaptively adjusts the portion of leased channels based on the number of ongoing and buffered PU flows. Furthermore, in the leased spectrum band, the SU flows with access priority employ dynamic spectrum access of channel aggregation, which enables one flow to occupy multiple channels for transmission in a dynamically changing environment. For performance evaluation, the continuous time Markov chain (CTMC) is developed to model our proposed strategy and conduct theoretical analyses. Numerical results demonstrate that the proposed strategy effectively improves the spectrum utilization and network capacity, while significantly reducing the forced termination probability and blocking probability of SU flows.publishedVersio
UCF-Crime Annotation: A Benchmark for Surveillance Video-and-Language Understanding
Surveillance videos are an essential component of daily life with various
critical applications, particularly in public security. However, current
surveillance video tasks mainly focus on classifying and localizing anomalous
events. Existing methods are limited to detecting and classifying the
predefined events with unsatisfactory generalization ability and semantic
understanding, although they have obtained considerable performance. To address
this issue, we propose constructing the first multimodal surveillance video
dataset by manually annotating the real-world surveillance dataset UCF-Crime
with fine-grained event content and timing. Our newly annotated dataset, UCA
(UCF-Crime Annotation), provides a novel benchmark for multimodal surveillance
video analysis. It not only describes events in detailed descriptions but also
provides precise temporal grounding of the events in 0.1-second intervals. UCA
contains 20,822 sentences, with an average length of 23 words, and its
annotated videos are as long as 102 hours. Furthermore, we benchmark the
state-of-the-art models of multiple multimodal tasks on this newly created
dataset, including temporal sentence grounding in videos, video captioning, and
dense video captioning. Through our experiments, we found that mainstream
models used in previously publicly available datasets perform poorly on
multimodal surveillance video scenarios, which highlights the necessity of
constructing this dataset. The link to our dataset and code is provided at:
https://github.com/Xuange923/UCA-dataset
Matching-based Hybrid Service Trading for Task Assignment over Dynamic Mobile Crowdsensing Networks
By opportunistically engaging mobile users (workers), mobile crowdsensing
(MCS) networks have emerged as important approach to facilitate sharing of
sensed/gathered data of heterogeneous mobile devices. To assign tasks among
workers and ensure low overheads, a series of stable matching mechanisms is
introduced in this paper, which are integrated into a novel hybrid service
trading paradigm consisting of futures trading mode and spot trading mode to
ensure seamless MCS service provisioning. In the futures trading mode, we
determine a set of long-term workers for each task through an
overbooking-enabled in-advance many-to-many matching (OIA3M) mechanism, while
characterizing the associated risks under statistical analysis. In the spot
trading mode, we investigate the impact of fluctuations in long-term workers'
resources on the violation of service quality requirements of tasks, and
formalize a spot trading mode for tasks with violated service quality
requirements under practical budget constraints, where the task-worker mapping
is carried out via onsite many-to-many matching (O3M) and onsite many-to-one
matching (OMOM). We theoretically show that our proposed matching mechanisms
satisfy stability, individual rationality, fairness and computational
efficiency. Comprehensive evaluations also verify the satisfaction of these
properties under practical network settings, while revealing commendable
performance on running time, participators' interactions, and service quality
Effect of Restricted Grazing Time on the Foraging Behavior and Movement of Tan Sheep Grazed on Desert Steppe
To investigate the effect of restricted grazing time on behavior of Tan sheep on desert steppe, forty 4-months old male Tan sheep with an original body weight (BW) of 15.62±0.33 kg were randomly allocated to 4 grazing groups which corresponded to 4 different restricted grazing time treatments of 2 h/d (G2), 4 h/d (G4), 8 h/d (G8) and 12 h/d (G12) access to pasture. The restricted grazing times had a significant impact on intake time, resting time, ruminating time, bite rate and movement. As the grazing time decreased, the proportion of time spent on intake, bite rate and grazing velocity significantly (p<0.05) increased, but resting and ruminating time clearly (p<0.05) decreased. The grazing months mainly depicted effect on intake time and grazing velocity. In conclusion, by varying their foraging behavior, Tan sheep could improve grazing efficiency to adapt well to the time-limited grazing circumstance
Development, validation, comparison, and implementation of a highly efficient and effective method using magnetic solid-phase extraction with hydrophilic-lipophilic-balanced materials for LC-MS/MS analysis of pesticides in seawater
Abstract(#br)To achieve multi-pesticides residue analysis in seawater, hydrophilic-lipophilic-balanced magnetic particles were designed and fabricated by swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe 3 O 4 @SiO 2 magnetic particles. The ratio of DVB to NVP was adjusted to achieve a proper balance in hydrophilicity and lipophilicity. The obtained magnetic particles were systematically characterized by TEM, SEM, FT-IR and vibrating sample magnetization. Based on the optimized magnetic nanoparticles, a sensitive magnetic solid-phase extraction method was developed for the simultaneous pre-concentration and determination of 96-pesticide residues from large-volume seawater samples prior to being detected by liquid chromatography-tandem mass spectrometry. Recoveries of pesticides in spiked seawater samples (0.001, 0.01, 0.1, 1.0 μg L −1 ) ranged from 62% to 112% with RSDs less than 21%. The method limits of detection of 96 pesticides ranged from 0.13 to 0.42 ng L −1 , the method limits of quantification of 96 pesticides ranged from 1.0 to 10 ng L −1 . The method was successfully applied to pesticide residue analysis in water samples from Jiulong River Estuary of China, demonstrating the prospects of this technique as a potential method for the rapid determination of trace levels of multi-pesticide residues in seawater
Development, validation, comparison, and implementation of a highly efficient and effective method using magnetic solid-phase extraction with hydrophilic-lipophilic-balanced materials for LC-MS/MS analysis of pesticides in seawater.
To achieve multi-pesticides residue analysis in seawater, hydrophilic-lipophilic-balanced magnetic particles were designed and fabricated by swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe3O4@SiO2 magnetic particles. The ratio of DVB to NVP was adjusted to achieve a proper balance in hydrophilicity and lipophilicity. The obtained magnetic particles were systematically characterized by TEM, SEM, FT-IR and vibrating sample magnetization. Based on the optimized magnetic nanoparticles, a sensitive magnetic solid-phase extraction method was developed for the simultaneous pre-concentration and determination of 96-pesticide residues from large-volume seawater samples prior to being detected by liquid chromatography-tandem mass spectrometry. Recoveries of pesticides in spiked seawater samples (0.001, 0.01, 0.1, 1.0 μg L-1) ranged from 62% to 112% with RSDs less than 21%. The method limits of detection of 96 pesticides ranged from 0.13 to 0.42 ng L-1, the method limits of quantification of 96 pesticides ranged from 1.0 to 10 ng L-1. The method was successfully applied to pesticide residue analysis in water samples from Jiulong River Estuary of China, demonstrating the prospects of this technique as a potential method for the rapid determination of trace levels of multi-pesticide residues in seawater
Compared the efficacy of mitoxantrone hydrochloride injection for tracing with radionuclide in sentinel lymph node biopsy of breast cancer
Background and purpose: Both domestic and foreign guidelines recommend the use of radionuclide as sentinel lymph node (SLN) biopsy (SLNB) tracer, however this technique has not been popularized in China for a variety of reasons. Mitoxantrone hydrochloride injection for tracing (MHI), a new strategy to identify lymph nodes, has not been tested for axillary node staging in breast cancer. This multicenter, self-controlled, non-inferiority trial aimed to evaluate the differences between MHI and radionuclide in SLNB tracing. Methods: The trial was conducted across 7 hospitals from December 2019 to December 2020. Patients with early-stage breast cancer received MHI and radionuclide (technetium 99 labeled sulfur colloid, 99mTc-Sc) as SLN tracers during the surgery. The number of SLNs detected and sentinel node detection rates of MHI and radionuclide were counted to evaluate differences in the tracing effects between the two tracers. Results: SLN detection rates of MHI and radionuclide were 96.9% (370/382) and 97.4% (372/382), respectively, with no significant difference (P>0.05). SLNs were co-detected by both tracers in 362 (94.7%) patients; 16 (4.1%) had adverse events possibly related to the trial drugs. Conclusion: In this study, it was found that the lymphatic tracing ability of MHI was not inferior to that of radionuclide. Meanwhile, the use of MHI does not require special instrument/equipment assistance
Genome Sequence of Striga asiatica Provides Insight into the Evolution of Plant Parasitism
Parasitic plants in the genus Striga, commonly known as witchweeds, cause major crop losses in sub-Saharan Africa and pose a threat to agriculture worldwide. An understanding of Striga parasite biology, which could lead to agricultural solutions, has been hampered by the lack of genome information. Here, we report the draft genome sequence of Striga asiatica with 34,577 predicted protein-coding genes, which reflects gene family contractions and expansions that are consistent with a three-phase model of parasitic plant genome evolution. Striga seeds germinate in response to host-derived strigolactones (SLs) and then develop a specialized penetration structure, the haustorium, to invade the host root. A family of SL receptors has undergone a striking expansion, suggesting a molecular basis for the evolution of broad host range among Striga spp. We found that genes involved in lateral root development in non-parasitic model species are coordinately induced during haustorium development in Striga, suggesting a pathway that was partly co-opted during the evolution of the haustorium. In addition, we found evidence for horizontal transfer of host genes as well as retrotransposons, indicating gene flow to S. asiatica from hosts. Our results provide valuable insights into the evolution of parasitism and a key resource for the future development of Striga control strategies.Peer reviewe
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