Secure Transmission of Terahertz Signals with Multiple Eavesdroppers.

The terahertz (THz) band is expected to become a key technology to meet the ever-increasing traffic demand for future 6G wireless communications, and a lot of efforts have been paid to develop its capacity. However, few studies have been concerned with the transmission security of such ultra-high-speed THz wireless links. In this paper, we comprehensively investigate the physical layer security (PLS) of a THz communication system in the presence of multiple eavesdroppers and beam scattering. The method of moments (MoM) was adopted so that the eavesdroppers' channel influenced by the PEC can be characterized. To establish a secure link, the traditional beamforming and artificial noise (AN) beamforming were considered as transmission schemes for comparison. For both schemes, we analyzed their secrecy transmission probability (STP) and ergodic secrecy capacity (ESC) in non-colluding and colluding cases, respectively. Numerical results show that eavesdroppers can indeed degrade the secrecy performance by changing the size or the location of the PEC, while the AN beamforming technique can be an effective candidate to counterbalance this adverse effect.

Storage Space Allocation Strategy for Digital Data with Message Importance.

This paper mainly focuses on the problem of lossy compression storage based on the data value that represents the subjective assessment of users when the storage size is still not enough after the conventional lossless data compression. To this end, we transform this problem to an optimization, which pursues the least importance-weighted reconstruction error in data reconstruction within limited total storage size, where the importance is adopted to characterize the data value from the viewpoint of users. Based on it, this paper puts forward an optimal allocation strategy in the storage of digital data by the exponential distortion measurement, which can make rational use of all the storage space. In fact, the theoretical results show that it is a kind of restrictive water-filling. It also characterizes the trade-off between the relative weighted reconstruction error and the available storage size. Consequently, if a relatively small part of total data value is allowed to lose, this strategy will improve the performance of data compression. Furthermore, this paper also presents that both the users' preferences and the special characteristics of data distribution can trigger the small-probability event scenarios where only a fraction of data can cover the vast majority of users' interests. Whether it is for one of the reasons above, the data with highly clustered message importance is beneficial to compression storage. In contrast, from the perspective of optimal storage space allocation based on data value, the data with a uniform information distribution is incompressible, which is consistent with that in the information theory.

[Effects of low intensity resistance training of blood flow restriction with different occlusion pressure on lower limb muscle and cardiopulmonary function of college students].

Objective: The study compared the effects of low intensity resistance training with blood flow restriction (BFR) with different occlusion pressure on lower limb muscle and cardiopulmonary function. Methods: Twenty-seven college students were randomly divided into three groups by different occlusion pressure: 0 mmHg (group C), 120 mmHg (group L) and 180 mmHg (group H). Before and after training (3 times a week for 12 weeks) with an inflatable cuff (20% 1RM, half squat), the muscle thickness(MTH)of rectus femoris and medius femoris, relative peak knee extensor moment(rM), peak power(P), relative maximal oxygen uptake(rVO2max), stroke volume(SV), cardiac output(CO), ejection fraction(EF) and other indicators were measured for all subjects. Results: When compared with pre-training, and rectus femoris, the MTH of medius femoris, rM, rVO2max, SV, CO and EF were significantly increased in group L and group H after 12 weeks training(P＜0.05, P＜0.01), as well as compared with group C after training(P＜0.05, P＜0.01). There was no significant difference between group L and group H after training. Conclusion: BFR training protocols under 120 mmHg or 180 mmHg pressure were effective in improving muscle and cardiopulmonary function.

Relationship between functional movement performance and health-related physical fitness of male college students / 中国学校卫生

Objective@#To analyze the relationship among cardiopulmonary endurance, body composition, flexibility, muscle strength and endurance with functional movement performance of male college students, and to explore the factors associated with the performance of functional movements.@*Methods@#A total of 112 male college students were selected, muscle power and flexibility test was based on the national student physical health standard, founctional movement screen created by Cook was used to test founctional movement performance.@*Results@#Male college students have poor flexibility, stability and control of functional movements, and high probability of compensatory or asymmetric movements; In-line lunge, trunk stability push-up were positively associated with cardiorespiratory fitness(r=0.17, 0.17, P<0.05); hurdle step, shoulder mobility, trunk stability push-up and rotary were negative associated with body composition(r=-0.17, -0.13, -0.25, -0.22,P<0.05); shoulder mobility, trunk stability push-up and rotary were positively associated with score of standing long jump, trunk stability push-up was positively associated with endurance of deltoid and trapetus as well as endurance of pectoralis major and latissimus dorsi; shoulder mobility was positively associated with score of sit and reach(r=0.17, P<0.01). The independent risk factors of functional performance of male college students, hurdle step(β=-0.02), trunk stability push-up (β=-0.12) and rotary were body fat rate(β=-0.03); the protective factors trunk stability push-up were body fat rate(β=-0.04), VO 2max (β=0.04) and endurance of pectoralis major and latissimus dorsi(β=0.03).@*Conclusion@#The functional performance of male college students was not optimistic, which could be improved by increasing health-related physical fitness.

Matching Users' Preference under Target Revenue Constraints in Data Recommendation Systems.

This paper focuses on the problem of finding a particular data recommendation strategy based on the user preference and a system expected revenue. To this end, we formulate this problem as an optimization by designing the recommendation mechanism as close to the user behavior as possible with a certain revenue constraint. In fact, the optimal recommendation distribution is the one that is the closest to the utility distribution in the sense of relative entropy and satisfies expected revenue. We show that the optimal recommendation distribution follows the same form as the message importance measure (MIM) if the target revenue is reasonable, i.e., neither too small nor too large. Therefore, the optimal recommendation distribution can be regarded as the normalized MIM, where the parameter, called importance coefficient, presents the concern of the system and switches the attention of the system over data sets with different occurring probability. By adjusting the importance coefficient, our MIM based framework of data recommendation can then be applied to systems with various system requirements and data distributions. Therefore, the obtained results illustrate the physical meaning of MIM from the data recommendation perspective and validate the rationality of MIM in one aspect.

Attention to the Variation of Probabilistic Events: Information Processing with Message Importance Measure.

Different probabilities of events attract different attention in many scenarios such as anomaly detection and security systems. To characterize the events' importance from a probabilistic perspective, the message importance measure (MIM) is proposed as a kind of semantics analysis tool. Similar to Shannon entropy, the MIM has its special function in information representation, in which the parameter of MIM plays a vital role. Actually, the parameter dominates the properties of MIM, based on which the MIM has three work regions where this measure can be used flexibly for different goals. When the parameter is positive but not large enough, the MIM not only provides a new viewpoint for information processing but also has some similarities with Shannon entropy in the information compression and transmission. In this regard, this paper first constructs a system model with message importance measure and proposes the message importance loss to enrich the information processing strategies. Moreover, the message importance loss capacity is proposed to measure the information importance harvest in a transmission. Furthermore, the message importance distortion function is discussed to give an upper bound of information compression based on the MIM. Additionally, the bitrate transmission constrained by the message importance loss is investigated to broaden the scope for Shannon information theory.

Recognizing Information Feature Variation: Message Importance Transfer Measure and Its Applications in Big Data.

Information transfer that characterizes the information feature variation can have a crucial impact on big data analytics and processing. Actually, the measure for information transfer can reflect the system change from the statistics by using the variable distributions, similar to Kullback-Leibler (KL) divergence and Renyi divergence. Furthermore, to some degree, small probability events may carry the most important part of the total message in an information transfer of big data. Therefore, it is significant to propose an information transfer measure with respect to the message importance from the viewpoint of small probability events. In this paper, we present the message importance transfer measure (MITM) and analyze its performance and applications in three aspects. First, we discuss the robustness of MITM by using it to measuring information distance. Then, we present a message importance transfer capacity by resorting to the MITM and give an upper bound for the information transfer process with disturbance. Finally, we apply the MITM to discuss the queue length selection, which is the fundamental problem of caching operation on mobile edge computing.

[The effects of 10-week core strength training on the body balance in the middle-aged men].

OBJECTIVE: To observe the effects of core strength training on the body balance of middle-aged men, which could provide evidence for improving the body balance and reducing the risk of falls in the middle-aged men. METHODS: Sixteen 50~60 years old men were randomly divided into experimental group (core strength training, n=8) and control group(n=8). Intermittent core strength trainings were used for dynamic and static training, push-pull training and unarmed lower limb strength training by suspension ropes and yoga mat. The time for training was 50~60 min/day, 4~5 times/week for a total of 10 weeks. The men in control group remained their original living habits. We measured the ability of body static balance and dynamic balance before and after the core strength training. RESULTS: ① Compared with before exercise training, both closed single foot standing time and the body dynamic balance were increased significantly in the experimental group after exercise training(P<0.01)(10.63±1.69 s vs 9.00±2.27 s; 77.38±10.94 vs 89.50±5.53). ② Compared with before exercise training, star excursion balance test(SEBT) values were significantly increased in the left leg(the right leg support) in eight directions and the right leg(the left leg support)in six directions (P<0.01). CONCLUSIONS: Ten-week core strength training can significantly increase the body static and dynamic balance in the middle-aged men.

[The effects of endurance training on IL-18 and IL-10 in athero-genic ApoE-/- mice].

OBJECTIVE: To investigate the effects of endurance training on interleukin-18(IL-18) and IL-10 in atherogenice apolipoprotein E gene knockout(ApoE-/-)mice and explore its possible mechanism preventing atherosclerosis occurrence. METHODS: Twenty male ApoE-/- mice (age:8 weeks) were randomly divided into atherosclerosis(AS)model group(AC) and exercise group(AE) and chose male C57BL/6J mice (age:8 weeks) as control group (CC). After 12 weeks, the aortic trunk closed heart was prepared for frozen section, which were used to observe the changes of plaque area and pathology. The expressions of IL-18 and IL-10 proteins and the levels of blood IL-18 and IL-10 were measured by ELISA. RESULTS: ① Twelve weeks high fat diet significantly resulted in typical AS lesion, however, endurance training markedly decreased AS plaque area and pathology in ApoE-/- mice(P<0.01). ②Compared with CC group, serum IL-18 and IL-10 levels were significantly increased in AC group and AE group and IL-18/IL-10 ratio was also increased markedly in AE group(P<0.01). Serum IL-18 level and IL-18/IL-10 ratio in AE group were all significantly lower than those in AC group (P<0.01).③Compared with CC group, the expressions of IL-10 and IL-18 proteins in aorta were significantly increased in AC group and AE group (P<0.01). The expression of IL-10 protein in aorta in AE group was markedly higher than that in AC group but IL-18 protein expression was significantly lower. CONCLUSIONS: Endurance training can prevent AS appeared through enhancing aortic anti-inflammatory capability by decreasing serum and aortic IL-18 levels and by increasing serum and aortic IL-10 level.

[The effects of high fat diet and endurance exercise on the aorta wall structure of experimental animal].

OBJECTIVE: Based on high fat diet induced the model of atherosclerosis (AS) in C57BL/6J mice, authors studied the effect of endurance exercise on the atherosclerostic formation. METHODS: Forty eight 8-week-old C57BL/6J mice were divided into four groups randomly (n=12): control (group N), 12-week atherosclerosis model group(group H), 12-week atherosclerosis model plus 11-week treadmill training group (group H + E) and 22-week atherosclerosis model group (group HS). Then, we observed the effects of endurance exercise on the ultra structure of aorta by electron microscope. RESULTS: Twenty weeks of high fat diet could result in serious AS in mice while endurance exercise could significantly antagonize or restrain the occur of AS. In addition, 10 weeks of endurance exercise could alleviate the symptom of pathological changes which already happened on aorta wall. CONCLUSION: It indicated that endurance exercise could effectively prevent and cure AS that induced by high fat diet.