Enhanced spin injection efficiency in a four-terminal double quantum dot system

Within the scheme of quantum rate equations, we investigate the spin-resolved transport through a double quantum dot system with four ferromagnetic terminals. It is found that the injection efficiency of spin-polarized electrons can be significantly improved compared with single dot case. When the magnetization in one of four ferromagnetic terminals is antiparallel with the other three, the polarization rate of the current through one dot can be greatly enhanced, accompanied by the drastic decrease of the current polarization rate through the other one. The mechanism is the exchange interaction between electrons in the two quantum dots, which can be a promising candidate for the improvement of the spin injection efficiency.Comment: 10 pages and 5 figure

Connecting routine, life order and recycling : a field study of waste management In Augustenborg

Recycling station is hardly a space imbued with neutrality. Hannah Arendt observed: "public space is where a people's dominant ethos of self is decided, normalized and regulated."(1985). Normality and dominant ethos of the society are patently advocated and promoted in the recycling station, in other words, the recycling station implies within it a normative way of behavior which is systematic and consistent recycling activity. Such desired normality is latently in accordance with the interest of the society and the expectation of the technocrats who designed the recycling facilities in place. However, there exists a great diversity of recycling behaviors in reality, some of which are in sharp contrast with the normality. The normality and dominant ethos of the society congregated in the field of recycling undergo a vigorous process filled with negotiation, appropriation and modification initiated by the users. Therefore, a better understanding of how waste management is perceived and experienced on the user end is crucial to both the organization of knowledge campaigns of waste management and the design of recycling facility. Key factors, phycologically and practically, that influence recycling perception and behavior will be brought under scrutiny in the thesis. The thesis argues that the practice of recycling conjures up a dynamic personal sphere where environmental consciousness, family values, individual identity, life order and concerns for practicality congregate. Recycling is never an isolated and static event, rather, it slides on a spectrum with two polar opposites. On one hand, recycling is pushed to the background, serving as a mindless routine. On the other, recycling becomes a personal ritual fully charged with meanings. Based on the data gathered from a four-month field work in Augustenborg, Malmö, the thesis examines how recycling is perceived and experienced on the user end to make explicit the gap between the designed and the lived practices in the field of waste management