56 research outputs found
Semantic Communications with Explicit Semantic Base for Image Transmission
Semantic communications, aiming at ensuring the successful delivery of the
meaning of information, are expected to be one of the potential techniques for
the next generation communications. However, the knowledge forming and
synchronizing mechanism that enables semantic communication systems to extract
and interpret the semantics of information according to the communication
intents is still immature. In this paper, we propose a semantic image
transmission framework with explicit semantic base (Seb), where Sebs are
generated and employed as the knowledge shared between the transmitter and the
receiver with flexible granularity. To represent images with Sebs, a novel
Seb-based reference image generator is proposed to generate Sebs and then
decompose the transmitted images. To further encode/decode the residual
information for precise image reconstruction, a Seb-based image encoder/decoder
is proposed. The key components of the proposed framework are optimized jointly
by end-to-end (E2E) training, where the loss function is dedicated designed to
tackle the problem of nondifferentiable operation in Seb-based reference image
generator by introducing a gradient approximation mechanism. Extensive
experiments show that the proposed framework outperforms state-of-art works by
0.5 - 1.5 dB in peak signal-to-noise ratio (PSNR) w.r.t. different
signal-to-noise ratio (SNR)
Recommended from our members
Using personally controlled air movement to improve comfort after simulated summer commute
People often feel uncomfortably warm and sweaty in their workspace after commuting there by walking or cycling in summer. This is because body heat stored during the commute takes a substantial time to dissipate. People complaining about this uncomfortable transition may cause operators to lower the thermostat setpoint, causing long-term overcooling and wasting energy. In addition, space cooling is slow, requiring minutes to take effect. This study addresses how to improve comfort in the transition by increasing the availability of convective cooling, where the response time is in seconds. Thirty-five subjects (17 men and 18 women) dressed in 0.6 clo en-tered a test room after exercising at 4.4 met for 15 min in 30 ºC. The exercise emulates the commute activity in summer. The test room was controlled to 24, 26, and 28 ºC, with and without the option of cooling using fan-produced horizontal airflow. Subjects were sedentary for 60 minutes, during which subjective thermal responses and physiological responses were measured. The enhanced convective and evaporative heat loss caused by fans significantly shortened the time needed to reach thermal comfort after the exercise-induced thermal stress and improved the final comfort level. Compared to a typical indoor condition of 24 ºC and still air, 26 and 28 ºC with fans provided equal or better comfort more quickly, and inherently required much less energy to do so. Our study suggests that personally controlled air movement should be available in spaces where thermal and metabolic down-steps take plac
Dynamic UAV Swarm Collaboration for Multi-Targets Tracking under Malicious Jamming: Joint Power, Path and Target Association Optimization
In this paper, the multi-target tracking (MTT) with an unmanned aerial
vehicle (UAV) swarm is investigated in the presence of jammers, where UAVs in
the swarm communicate with each other to exchange information of targets during
tracking. The communication between UAVs suffers from severe interference,
including inter-UAV interference and jamming, thus leading to a deteriorated
quality of MTT. To mitigate the interference and achieve MTT, we formulate a
interference minimization problem by jointly optimizing UAV's sub-swarm
division, trajectory, and power, subject to the constraint of MTT, collision
prevention, flying ability, and UAV energy consumption. Due to the multiple
coupling of sub-swarm division, trajectory, and power, the proposed
optimization problem is NP-hard. To solve this challenging problem, it is
decomposed into three subproblems, i.e., target association, path plan, and
power control. First, a cluster-evolutionary target association (CETA)
algorithm is proposed, which involves dividing the UAV swarm into the multiple
sub-swarms and individually matching these sub-swarms to targets. Second, a
jamming-sensitive and singular case tolerance (JSSCT)-artificial potential
field (APF) algorithm is proposed to plan trajectory for tracking the targets.
Third, we develop a jamming-aware mean field game (JA-MFG) power control
scheme, where a novel cost function is established considering the total
interference. Finally, to minimize the total interference, a dynamic
collaboration approach is designed. Simulation results validate that the
proposed dynamic collaboration approach reduces average total interference,
tracking steps, and target switching times by 28%, 33%, and 48%, respectively,
comparing to existing baselines.Comment: 14 pages, 17 figure
Childhood Sexual Abuse and the Development of Recurrent Major Depression in Chinese Women
Background
Our prior study in Han Chinese women has shown that women with a history of childhood sexual abuse (CSA) are at increased risk for developing major depression (MD). Would this relationship be found in our whole data set? Method
Three levels of CSA (non-genital, genital, and intercourse) were assessed by self-report in two groups of Han Chinese women: 6017 clinically ascertained with recurrent MD and 5983 matched controls. Diagnostic and other risk factor information was assessed at personal interview. Odds ratios (ORs) were calculated by logistic regression. Results
We confirmed earlier results by replicating prior analyses in 3,950 new recurrent MD cases. There were no significant differences between the two data sets. Any form of CSA was significantly associated with recurrent MD (OR 4.06, 95% confidence interval (CI) [3.19–5.24]). This association strengthened with increasing CSA severity: non-genital (OR 2.21, 95% CI 1.58–3.15), genital (OR 5.24, 95% CI 3.52–8.15) and intercourse (OR 10.65, 95% CI 5.56–23.71). Among the depressed women, those with CSA had an earlier age of onset, longer depressive episodes. Recurrent MD patients those with CSA had an increased risk for dysthymia (OR 1.60, 95%CI 1.11–2.27) and phobia (OR 1.41, 95%CI 1.09–1.80). Any form of CSA was significantly associated with suicidal ideation or attempt (OR 1.50, 95% CI 1.20–1.89) and feelings of worthlessness or guilt (OR 1.41, 95% CI 1.02–2.02). Intercourse (OR 3.47, 95%CI 1.66–8.22), use of force and threats (OR 1.95, 95%CI 1.05–3.82) and how strongly the victims were affected at the time (OR 1.39, 95%CI 1.20–1.64) were significantly associated with recurrent MD
Associations of Educational Attainment, Occupation, Social Class and Major Depressive Disorder among Han Chinese Women
Background
The prevalence of major depressive disorder (MDD) is higher in those with low levels of educational attainment, the unemployed and those with low social status. However the extent to which these factors cause MDD is unclear. Most of the available data comes from studies in developed countries, and these findings may not extrapolate to developing countries. Examining the relationship between MDD and socio economic status in China is likely to add to the debate because of the radical economic and social changes occurring in China over the last 30 years. Principal findings
We report results from 3,639 Chinese women with recurrent MDD and 3,800 controls. Highly significant odds ratios (ORs) were observed between MDD and full time employment (OR = 0.36, 95% CI = 0.25–0.46, logP = 78), social status (OR = 0.83, 95% CI = 0.77–0.87, logP = 13.3) and education attainment (OR = 0.90, 95% CI = 0.86–0.90, logP = 6.8). We found a monotonic relationship between increasing age and increasing levels of educational attainment. Those with only primary school education have significantly more episodes of MDD (mean 6.5, P-value = 0.009) and have a clinically more severe disorder, while those with higher educational attainment are likely to manifest more comorbid anxiety disorders. Conclusions
In China lower socioeconomic position is associated with increased rates of MDD, as it is elsewhere in the world. Significantly more episodes of MDD occur among those with lower educational attainment (rather than longer episodes of disease), consistent with the hypothesis that the lower socioeconomic position increases the likelihood of developing MDD. The phenomenology of MDD varies according to the degree of educational attainment: higher educational attainment not only appears to protect against MDD but alters its presentation, to a more anxious phenotype
Recommended from our members
Using personally controlled air movement to improve comfort after simulated summer commute
People often feel uncomfortably warm and sweaty in their workspace after commuting there by walking or cycling in summer. This is because body heat stored during the commute takes a substantial time to dissipate. People complaining about this uncomfortable transition may cause operators to lower the thermostat setpoint, causing long-term overcooling and wasting energy. In addition, space cooling is slow, requiring minutes to take effect. This study addresses how to improve comfort in the transition by increasing the availability of convective cooling, where the response time is in seconds. Thirty-five subjects (17 men and 18 women) dressed in 0.6 clo en-tered a test room after exercising at 4.4 met for 15 min in 30 ºC. The exercise emulates the commute activity in summer. The test room was controlled to 24, 26, and 28 ºC, with and without the option of cooling using fan-produced horizontal airflow. Subjects were sedentary for 60 minutes, during which subjective thermal responses and physiological responses were measured. The enhanced convective and evaporative heat loss caused by fans significantly shortened the time needed to reach thermal comfort after the exercise-induced thermal stress and improved the final comfort level. Compared to a typical indoor condition of 24 ºC and still air, 26 and 28 ºC with fans provided equal or better comfort more quickly, and inherently required much less energy to do so. Our study suggests that personally controlled air movement should be available in spaces where thermal and metabolic down-steps take plac
Highly Enhanced OER Performance by Er-Doped Fe-MOF Nanoarray at Large Current Densities
Great expectations have been held for the electrochemical splitting of water for producing hydrogen as a significant carbon-neutral technology aimed at solving the global energy crisis and greenhouse gas issues. However, the oxygen evolution reaction (OER) process must be energetically catalyzed over a long period at high output, leading to challenges for efficient and stable processing of electrodes for practical purposes. Here, we first prepared Fe-MOF nanosheet arrays on nickel foam via rare-earth erbium doping (Er0.4 Fe-MOF/NF) and applied them as OER electrocatalysts. The Er0.4 Fe-MOF/NF exhibited wonderful OER performance and could yield a 100 mA cm−2 current density at an overpotential of 248 mV with outstanding long-term electrochemical durability for at least 100 h. At large current densities of 500 and 1000 mA cm−2, overpotentials of only 297 mV and 326 mV were achieved, respectively, revealing its potential in industrial applications. The enhancement was attributed to the synergistic effects of the Fe and Er sites, with Er playing a supporting role in the engineering of the electronic states of the Fe sites to endow them with enhanced OER activity. Such a strategy of engineering the OER activity of Fe-MOF via rare-earth ion doping paves a new avenue to design other MOF catalysts for industrial OER applications
Porous Molybdenum Nitride Nanosphere as Carrier-Free and Efficient Nitric Oxide Donor for Synergistic Nitric Oxide and Chemo/Sonodynamic Therapy
Given its abundant physiological functions, nitric oxide
(NO) has
attracted much attention as a cancer therapy. The sensitive release
and great supply capacity are significant indicators of NO donors
and their performance. Here, a transition metal nitride (TMN) MoN@PEG
is adopted as an efficient NO donor. The release process starts with
H+-triggered denitrogen owing to the high electronegativity
of the N atom and weak Mo–N bond. Then, these active NHx are oxidized by O2 and other
reactive oxygen species (ROS) to form NO, endowing specific release
to the tumor microenvironment (TME). With a porous nanosphere structure
(80 nm), MoN@PEG does not require an extra carrier for NO delivery,
contributing to ultrahigh atomic utilization for outstanding release
ability (94.1 ± 5.6 μM). In addition, it can also serve
as a peroxidase and sonosensitizer for anticancer treatment. To further
improve the charge separation, MoN-Pt@PEG was prepared to enhance
the sonodynamic therapy (SDT) effect. Accordingly, ultrasound (US)
further promotes NO generation due to more ROS generation, facilitating
in situ peroxynitrite (·ONOO–) generation with great cytotoxicity. At the same time, the nanostructure
also degrades gradually, leading to high elimination (94.6%) via feces
and urine within 14-day. The synergistic NO and chemo-/sono-dynamic
therapy brings prominent antitumor efficiency and further activates
the immune response to inhibit metastasis and recurrence. This work
develops a family of NO donors that would further widen the application
of NO therapy in other fields
- …