The popularity of e-commerce has impacted traditional retail business. Farmer cooperatives running green agri-food pick-your-own (PYO) farms are facing the choice of whether or not to adopt online channels. PYO operation refers to consumers picking and purchasing the agri-food growing on a farm, and due to it being environmentally-friendly, healthy, and popular, it has been widely adopted by many farm cooperatives. This paper aims to discuss the practicality of introducing online channels to already established PYO farms in the green agri-food supply chain (GASC), who can personally take charge of the online channel or transfer it to one online retailer. Firstly, we constructed the demand functions of green agri-food by putting consumer utility, the freshness of agri-food, and transportation cost into consideration. Secondly, five decision models are built to characterize five operation modes, namely pure PYO mode, self-operated dual-channel mode, decentralized dual-channel mode, centralized dual-channel mode, and contractual cooperation mode. Furthermore, by taking price, demand, and profit with different modes into consideration, we are able to explore the introduction of online channels and green brand construction. Finally, numerical analysis is performed. We found that: (1) introducing an online channel is preferable strategy since the profit of the farmer cooperative in pure PYO mode is always less than the profit of a farmer cooperative in non-self-operated dual-channel modes; (2) the decision of self-operating an online channel is related to the fixed cost of creating a new online channel and the green food brand effect of online channel, and it is the optimal mode in some cases, while the contractual cooperation mode is the optimal mode in the remaining cases; and (3) the green food brand effect of online channels is does not necessarily improve with scale, and the initial freshness has a positive relationship to the profit, demand, and price of farmer cooperatives and online retailers.

Background: One-lung ventilation (OLV) is becoming an essential component of thoracic anesthesia.The two principal devices used for OLV are a double-lumen tube (DLT) and a bronchial blocker (BB).We hypothesized that the use of a BB with the disconnection technique would improve the quality of lung collapse in video-assisted thoracoscopic surgery (VATS). Methods: Seventy-five patients undergoing scheduled VATS were enrolled in this study and were randomly divided into two groups: a left-sided DLT group (Group D) and a BB with the disconnection technique group (Group B). OLV was initiated when the surgeon performed the skin incision. In Group D, the left channel of the DLT was opened to the air. In Group B, the lung was deflated via the disconnection technique, thus opening the breathing circuit to the air fifteen seconds after opening the pleura. The mean arterial pressure (MAP) and heart rate (HR) during induction; the quality of lung collapse 1 and 10 minutes after pleural opening; the time required for complete lung collapse; the correct placement of the device; and the number of patients suffering from a sore throat after surgery were recorded. Results: Compared with the use of the DLT, the use of the BB with the disconnection technique was associated with a similar quality of lung collapse, a comparable required time for total lung collapse (P>0.05, respectively), a lower incidence of sore throat both when leaving the PACU and 24 hours after surgery (34.2% vs. 13.5%, 15.8% vs. 5.4%, P<0.05, respectively) and fewer hemodynamic fluctuations after intubation both one and ten minutes after pleural opening. Conclusions: The use of a BB with the disconnection technique in VATS offers an effective method for improving the quality of lung collapse and reducing postoperative sore throat.

Energy cascade is one of the most prominent features of turbulence. Energy is injected at large scales, like fluid scales, then cascades to small scales through non-linear interactions, and finally dissipated at kinetic scales, leading to plasma heating and particle acceleration and the formation of suprathermal tails in the particle energy spectrum (Kiyani et al., 2015). Space plasma is typical of weak collisionality; hence collisionless mechanisms play a critical role in turbulent energy dissipation in space plasmas (Chen, 2016;Howes, 2017;Matthaeus et al., 2015). How the particles are heated/accelerated by turbulence is one of the most outstanding questions in plasma turbulence; however, the mechanism of turbulent energy dissipation and the consequent plasma heating is not fully understood after decades of intensive study. Different types of acceleration mechanisms have been proposed to explain plasma heating by the turbulent cascade in collisionless plasma. These mechanisms can be generally classified into two categories: resonant acceleration and non-resonant acceleration. The dissipation of waves is usually due to the resonance between fields and particles thereby transferring energy to the particles, which can work over a long distance and a long time. It includes Landau damping, cyclotron damping, and transit-time damping (

No abstract

How are particles being energized by turbulent electromagnetic fields is an outstanding question in plasma physics and astrophysics. This paper investigates the electron acceleration mechanism in strong turbulence (δB/B0 ~ 1) in the Earth’s magnetosheath based on the novel observations of the Magnetospheric Multiscale (MMS) mission. We find that electrons are magnetized in turbulent fields for the majority of the time. By directly calculating the electron acceleration rate from Fermi, betatron mechanism, and parallel electric field, it is found that electrons are primarily accelerated by the parallel electric field within coherent structures. Moreover, the acceleration rate by parallel electric fields increases as the spatial scale reduces, with the most intense acceleration occurring over about one ion inertial length. This study is an important step towards fully understanding the turbulent energy dissipation in weakly collisional plasmas.