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Grant-free random access (GFRA) can reduce the access delay and signaling cost, and satisfy the short transmission packet and strict delay constraints requirement in internet of things (IoT). IoT is a major trend in the future, which is characterized by the variety of applications and devices. However, most existing studies on GFRA only consider a single type of device and omit the effect of access delay. In this paper, we study GFRA in multicell massive multiple-input multiple-output (MIMO) systems where different types of devices with various configurations and requirements co-exist. By introducing the backoff mechanism, each device is randomly activated according to the backoff parameter, and active devices randomly select an orthogonal pilot sequence from a predefined pilot pool. An analytical approximation of the average spectral efficiency for each type of device is derived. Based on it, we obtain the optimal backoff parameter for each type of devices under their delay constraints. It is found that the optimal backoff parameters are closely related to the device number and delay constraint. In general, devices that have larger quantity should have more backoff time before they are allowed to access. However, as the delay constraint become stricter, the required backoff time reduces gradually, and the device with larger quantity may have less backoff time than that with smaller quantity when its delay constraint is extremely strict. When the pilot length is short, the effect of delay constraints mentioned above works more obviously. [ABSTRACT FROM AUTHOR]

Lophatheri Herba is a traditional Chinese medicine, which is commonly used in the treatment of fever, stomatitis, urodynia. The aim of the study is to evaluate the antidiarrheal activity of the ethanol extract of Lophatheri Herba (Gramineae, ELH) and observe its effect on isolated jejunum smooth muscle in rabbits, so that we can provide a possible pharmacological basis for its clinical use. Methods: In vivo, the antidiarrheal activity of ELH (250, 500 and 1000 mg/kg; orally) in castor oil-induced Kun Ming mice was evaluated. In vitro, the effect of ELH (0.01-10 mg/mL) on the spontaneous and ACh (10µM)/K+ (60mM)-induced contraction of isolated rabbit jejunum smooth muscle was studied. The possible mechanism of spasmolytic effect of ELH (1, 3mg/mL) was explored by pretreatment of intestinal tract with CaCl2. Results: ELH (500 and 1000mg/kg) exhibited antidiarrheal effect and it (0.01-10 mg/mL) inhibited the spontaneous and ACh/K+ -induced contraction with an EC50 value of 1.27 (0.89-1.34), 0.76 (0.54-1.02) and 0.34 (0.27- 0.53), it also shifted the concentration-response curves of CaCl2 to right with decreased in max, similar to verapamil. Conclusions: ELH has significant antidiarrheal and spasmolytic effect, this provides the pharmacological basis for use in gastrointestinal disorders. [ABSTRACT FROM AUTHOR]

Scutellaria barbata (S. barbata), a traditional herbal medicine used in southern China, possesses antiinflammatory, antitumor, spasmolytic and expectorant effects. However, there are not many recent studies on its gastrointestinal effects. This study aimed to evaluate the antidiarrheal effect of the ethanol extract of S. barbata (SBE) and its effect on the isolated jejunum smooth muscle. Methods: The antidiarrheal effect of SBE (doses: 125, 250 and 500 mg/kg) on castor oil-induced diarrhea was investigated in vivo. The effect of SBE (0.01-10 mg/mL) on spontaneous or acetylcholine chloride (ACh, 10μM)/KCl (60mM)-induced contraction of isolated rabbit jejunum smooth muscle was examined in vitro. The possible spasmolytic mechanism of SBE (1 and 3mg/mL) was analyzed by accumulating CaCl2 in a Ca2+-free high-K+ (60mM) solution. Results: SBE (125, 250 and 500mg/kg) could delay the initial semi-solid onset time of mice and also reduce the diarrhea index in vivo. Furthermore, SBE (0.01-10mg/mL) could alleviate the spontaneous or ACh/KCl-induced contraction in vitro. SBE (1 and 3mg/mL) also inhibited the contraction induced by CaCl2, and the concentration–response curves of CaCl2 moved downward and to the right, similar to those of verapamil (0.01 and 0.1μM). Conclusions: SBE exerts antidiarrheal and spasmolytic effects, which provides a pharmacological basis for its use in functional gastrointestinal disorders. [ABSTRACT FROM AUTHOR]