Which Factors Determine User’s First and Repeat Online Music Listening Respectively? Music Itself, User Itself, or Online Feedback

In the era of Web 2.0, does online feedback mainly dominant online users’ buying behavior, or are user’s own preference and product quality still important? Previous studies paid more attention to the influence of online feedback on users’ online buying behavior, however this paper focuses on how users’ own factors, product quality related factors and online feedback factors together influence a user’s buying behavior, and also how does this effect change as time goes by. Taking online music as our research industry and using the data from Last.fm website, this research shows that users’ preference and product quality are still the two most dominate factors influencing users’ online music listening, while online feedback plays an important role on users’ first listening. It is also found that the different influences of crowds and friends

Scala with Explicit Nulls

The Scala programming language makes all reference types implicitly nullable. This is a problem, because null references do not support most operations that do make sense on regular objects, leading to runtime errors. In this paper, we present a modification to the Scala type system that makes nullability explicit in the types. Specifically, we make reference types non-nullable by default, while still allowing for nullable types via union types. We have implemented this design for explicit nulls as a fork of the Dotty (Scala 3) compiler. We evaluate our scheme by migrating a number of Scala libraries to use explicit nulls. Finally, we give a denotational semantics of type nullification, the interoperability layer between Java and Scala with explicit nulls. We show a soundness theorem stating that, for variants of System F_? that model Java and Scala, nullification preserves values of types

Workplace Engagement Around Stewardship and Recyling in a Healthcare Setting

The healthcare industry is second only to the food industry in overall waste production, and there are many opportunities to mitigate the environmental impacts of waste through waste reduction and recycling programs in healthcare. Beaumont Royal Oak is a 1,000-bed hospital in Southeast Michigan that is part of an eight-hospital, non-profit health system called Beaumont Health. Beaumont Royal Oak is unique in that it has a voluntary training program that educates employees on environmental stewardship in the work place. The Green Officer program is administered by a Green Team made up of leaders in the hospital. In addition to running the Green Officer training program, the Green Team also implements other environmental stewardship initiatives at the hospital. While the Green Team had been successful in recruiting 483 employees to undergo the Green Officer certification program at Royal Oak, as of January 2015, they lacked information about whether Green Officer’s attitudes, knowledge, and behaviors differed from non-trained employees. At the same time, data on the hospital’s waste management revealed that the hospital’s recycling rate was lower than other hospitals with dedicated stewardship programs. This master’s project attempted to answer two questions: (1) how do Beaumont Royal Oak staff perceive and engage in environmental stewardship in the work place, and (2) how can Beaumont Royal Oak increase its recycling rate? To help us answer the second question, we used the Community-Based Social Marketing (CBSM) framework to give us guidance on how to address recycling in particular. The framework helped us focus on identifying barriers and benefits to recycling and engagement in environmental stewardship. We employed a wide variety of methods, including site visits, a literature review, an online survey, and employee interviews to answer our two questions. Our survey formed the crux of our data collection process and the findings from it provided the foundation for our recommendations. We used Qualtrics software to design our 10-minute, online survey which we distributed to both Green Officers and non-Green officers within the hospital. The goals of this survey instrument were two-fold: one, to gather data about environmental stewardship among employees at Beaumont Royal Oak, and two, to identify reasons why employees were not recycling at Beaumont Royal Oak. The first half of our survey measured whether there were differences between the environmental behavior and attitudes reported by Green Officers and non-Green Officers, while the second half narrowed in on recycling and measured employee knowledge and awareness of recycling procedures, self-reported recycling behaviors, and employee perceptions of barriers to recycling. We conducted our analysis based on a sample of 294 responses, composed of 116 GOs and 178 non- GOs. Based on our analysis, we saw that attitudes towards the hospital’s work in environmental stewardship were positive across all employees suggesting ample support for future stewardship programming. Green Officers, however, reported practicing environmental stewardship behaviors in the work place more often than their colleagues who are not Green Officers. This finding suggested that Green Officers are a key group to include in developing and rolling out behavior change interventions. The second portion of the survey focused on recycling, and for all items that we asked about, we found that Green Officers recycle them more frequently than employees who have not been trained. Our survey findings demonstrated that Green Officers are also more knowledgeable about what is recyclable in the hospital. However, across both groups we found that there was a lower level of knowledge about how recycling worked in the hospital. When we asked about barriers to recycling, we found that non- Green Officers reported finding recycling more difficult than Green Officers. They consider it more inconvenient, they are more confused about labels, and they do not feel it is as worthwhile as their Green Officers counterparts do. They also reported feeling less encouragement from supervisors and colleagues to recycle. The barriers identified by respondents demonstrated a need for greater communication about how the recycling program works and how the hospital is performing over time. The physical infrastructure of the recycling bins could also use greater standardization, while still keeping unique needs for different types of workspaces in mind. Based on our site visits, survey, literature review, and interviews, we created six recommendations that fit into three themes: convenience, awareness and knowledge, and motivation. These six recommendations are to increase bin availability, standardize bin appearance, inform employees how and where to recycle, tap into effective communication channels, renew commitments regularly, and to recognize recycling leaders for their efforts. A summary table of recommendations is shown in Section 7.3. After describing our recommendations, we provide guidance to Beaumont for completing the final steps of the CBSM process. This includes piloting, evaluating, and adjusting strategies, then scaling them up across the hospital. In conclusion, this project helps the Beaumont RO Green Team understand the current state of attitudes, knowledge, and engagement regarding environmental stewardship and recycling. After investing heavily in training hundreds of GOs, a feat unique in healthcare organizations across the country, there is still much more to do to help GOs succeed in helping their peers be better stewards at work. This project contributes to the small body of knowledge surrounding healthcare professionals’ opinions on environmental issues. This is an important contribution because healthcare professionals are trusted members of the community and can be strong environmental leaders with the right support and direction.Master of ScienceNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/117634/1/Masters Project Beaumont Sustainability Final Report.pd

Scala with Explicit Nulls (Artifact)

This artifact is a companion to the paper "Scala with Explicit Nulls", where we present a modification to the Scala type system that makes nullability explicit in the types. Specifically, we make reference types non-nullable by default, while still allowing for nullable types via union types. The artifact contains an implementation of this new type system design as a fork of the Dotty (Scala 3) compiler. Additionally, the artifact contains the source code of multiple Scala libraries that we used to evaluate our design

Profit-Maximizing Planning and Control of Battery Energy Storage Systems for Primary Frequency Control

We consider a two-level profit-maximizing strategy, including planning and control, for battery energy storage system (BESS) owners that participate in the primary frequency control (PFC) market. Specifically, the optimal BESS control minimizes the operating cost by keeping the state of charge (SoC) in an optimal range. Through rigorous analysis, we prove that the optimal BESS control is a "state-invariant" strategy in the sense that the optimal SoC range does not vary with the state of the system. As such, the optimal control strategy can be computed offline once and for all with very low complexity. Regarding the BESS planning, we prove that the the minimum operating cost is a decreasing convex function of the BESS energy capacity. This leads to the optimal BESS sizing that strikes a balance between the capital investment and operating cost. Our work here provides a useful theoretical framework for understanding the planning and control strategies that maximize the economic benefits of BESSs in ancillary service markets

Protease Cleavage Leads to Formation of Mature Trimer Interface in HIV-1 Capsid

During retrovirus particle maturation, the assembled Gag polyprotein is cleaved by the viral protease into matrix (MA), capsid (CA), and nucleocapsid (NC) proteins. To form the mature viral capsid, CA rearranges, resulting in a lattice composed of hexameric and pentameric CA units. Recent structural studies of assembled HIV-1 CA revealed several inter-subunit interfaces in the capsid lattice, including a three-fold interhexamer interface that is critical for proper capsid stability. Although a general architecture of immature particles has been provided by cryo-electron tomographic studies, the structural details of the immature particle and the maturation pathway remain unknown. Here, we used cryo-electron microscopy (cryoEM) to determine the structure of tubular assemblies of the HIV-1 CA-SP1-NC protein. Relative to the mature assembled CA structure, we observed a marked conformational difference in the position of the CA-CTD relative to the NTD in the CA-SP1-NC assembly, involving the flexible hinge connecting the two domains. This difference was verified via engineered disulfide crosslinking, revealing that inter-hexamer contacts, in particular those at the pseudo three-fold axis, are altered in the CA-SP1-NC assemblies compared to the CA assemblies. Results from crosslinking analyses of mature and immature HIV-1 particles containing the same Cys substitutions in the Gag protein are consistent with these findings. We further show that cleavage of preassembled CA-SP1-NC by HIV-1 protease in vitro leads to release of SP1 and NC without disassembly of the lattice. Collectively, our results indicate that the proteolytic cleavage of Gag leads to a structural reorganization of the polypeptide and creates the three-fold interhexamer interface, important for the formation of infectious HIV-1 particles. © 2012 Meng et al

Women as Victims of ‘Misogyny’: Re-centering Gender Marginalization

Among various views concerning the nature of womanhood, one kind of divergence between the materialist and the pluralist account centres on whether a woman should be defined or identified based on her typical female biological features. The former treats “woman” as the social meaning of the biological female, while the latter insists that one can be a woman in virtue of their internal identity without also having the normatively associated biological features. In this paper, I argue against the latter view that the inclusion or demarginalization of transwomen requires more than self-identification and that it demands the recognition of the role of “misogyny”