Place-making in public spaces is an important and worthy objective in the field of architecture. Sense of place is rooted in the dynamic interaction among people, space and activities. Hence, scholars observed human behaviors in successful public spaces and explored how the physical environment supports users' goals, expectations, activities and social interactions. Consequently, designers adopted the findings of these studies and created inhabitable public spaces in the urban area in which activities are diverse, social interactions are plentiful and sense of place is attached. What distinguishes public spaces from private spaces is the interaction partners. In public spaces, people interact with strangers whereas in private spaces, users participate in interpersonal behaviors with acquaintances. However, the ubiquitous use of digital media devices has blurred the line between public and private spaces. It modifies human behaviors and produces new genres of public spaces: the socializing private space and the privatizing public space. In the socializing private space, people participate in public activities and interact with strangers in social networking sites, online video games and news forums while the body is physically situated in private environments, e.g. home; whereas in privatizing public space, through digital media devices, users isolate themselves from other participants and build private zones to interact with acquaintances in physical public environments, such as local coffee shop and urban plazas. The juxtaposition of public and private life has challenged the existing theories of place-making in public spaces. Following the step of previous studies in social interactions and public spaces, this research adopts behavioral observations as the major methods to investigate current public spaces. Different types of computer-mediated public spaces were selected and examined. After careful investigations and analyses, the findings of this research pointed to two directions. On one hand, in the same type of computer-mediated public spaces, the ability to closely observe the interaction partners facilitates social interactions and enhances sense of place. If users are able to perceive more visual cues of appropriate behaviors, they experience better social interactions and attach sense of place to the environment. On the other hand, each type of computer-mediated public spaces is equipped with its social potentials and design problems. Although users somehow experience perception and interaction difficulties in the socializing private space due to the limited visibility to the interaction partners, the worldwide social pleasure, unexpectedness and exclusive activities associate the environment with sense of place. In the privatizing public spaces, people are able to directly sense, consciously understand, and automatically response each other; however, their ignorance of physical surrounding decreases sense of place. Therefore, by learning from different types of computer-mediated public spaces, the outcome of this research contributes to the design of both physical and virtual public spaces. It provides practical suggestions to the designs of information technologies as well as spatial designers. Furthermore, the analysis scheme and experimental process of this research extend the methodological approach for the future research of social interactions in public spaces.

The most prevalent human carcinogen is sunlight-associated UV, a physiologic dose of which generates thousands of DNA lesions per cell, mostly of two types: cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs). To cope with these lesions that are DNA- distorting and mutagenic, cells trigger ATR-mediated checkpoint signaling to regulate diverse processes including cell cycle arrest, DNA replication, DNA repair, and apoptosis. These ATR- mediated processes determine the mutagenic outcomes of UV-damaged cells. Thus, elucidating the fundamental mechanism by which cells sense UV lesions and activate DNA damage response pathways would be important for our understanding and control of UV carcinogenesis. Although it is known that UV generates distinct types of lesions and triggers DNA damage responses, it remains unclear whether and how these two structurally distinct types of UV lesions are different in their abilities to activate ATR. We hypothesized that there are striking differences in the mechanisms and impact of these two lesion types on DNA replication and DNA damage responses. To determine the individual contributions of CPD and 6-4PP to ATR activation (Aim 1), we generated cells with a single type of lesion (using photolyases that selectively repair either CPD or 6-4PP) and evaluated lesion-specific ATR activation by multiparameter flow cytometry. Strikingly, we found that the ATR-Chk1 pathway is potently activated by 6-4PP, but not by CPD lesions. To investigate the mechanism by which only 6-4PP activates ATR (Aim 2), we examined the effect of each lesion type on replication progression. Using microfluidic-assisted replication track analysis (maRTA), we found that 6-4PPs, but not CPDs, markedly impede DNA replication across the genome. Moreover, we demonstrated that only 6-4PPs preferentially become surrounded by single-stranded DNA in S phase, indicating selective and prolonged replication blockage at 6-4PPs. Taken together, 6-4PPs, although 8- fold fewer in number than CPDs, are critical for replication blockage and activation of the UV- induced ATR-Chk1 pathway. This study identifying the respective roles of CPD and 6-4PP lesions that occur at dipyrimidine sites provides a molecular basis for their remarkably distinct effects on DNA damage responses and insight into the mechanisms of UV carcinogenesis.

This paper studies a job-assignment model incorporating taste discrimination and statistical discrimination simultaneously. We argue that when taste discrimination of some employers can affect the human capital investment behavior of a particular group of workers, other employers without taste discrimination will take this effect into account when hiring. Statistical discrimination thus arises naturally and is influenced by the degree of taste discrimination. We demonstrate that even if employers have ex-ante homogeneous beliefs about different groups, this belief can be transformed into negative stereotypes by taste discrimination. When such externalities exist, affirmative-action policies need to persist in the long run, and once removed, inequality still occurs. Moreover, we show that the specific direction of impact on statistical discrimination depends on the relative strength of the two effects: (i) Compared to other groups, stricter standards lead to lower investment incentives. (ii) Compared to non-investors within the same group, stricter standards lead to better identification of investments.