The interaction between e-shopping and store shopping: empirical evidence from Nanjing, China

The rise of e-shopping significantly changes the way that people shop. Transportation planners have a keen interest in the substitution of e-shopping for store shopping and its impact on transportation systems. The literature offers mixed findings on the relationship between online and store shopping. Few studies have explored this relationship in China where e-shopping has proliferated and retail land use and transportation systems have evolved. Using data gathered from adult Internet users in Nanjing, this paper applies structural equation modeling to investigate the relationships among store shopping, online shopping, and online searching. The results show that online shopping and store shopping have a positive association, however, the effect is from the latter to the former. Online searching positively influences both online shopping and store shopping. These results imply that e-shopping as an information channel promotes store shopping

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Examining the effect of the Hiawatha LRT on auto use in the Twin Cities

Many studies have investigated the impact of rail transit on transit use. However, few have focused on auto use. This study explores the effect of the Hiawatha LRT in Minneapolis on vehicle miles driven (VMD). Negative binomial models show that Hiawatha residents drive shorter distance than those in urban and suburban control corridors, after demographics and neighborhood characteristics are controlled for. The LRT can reduce an urban resident\u27s VMD by about 20%, all else equal. Once attitudes are included in the model, however, the differences become insignificant. Demographics and attitudes altogether are more important in influencing auto use than the built environment. Overall, the LRT reduces driving because it enables new housing development and allows those valuing transit to better match their attitudes

Residential Preference and Choice of Movers in Light Rail Neighborhoods in Minneapolis, Minnesota

Light rail transit (LRT) has advocated for ridership growth, but not all residents move to LRT corridors because of transit. This study explores motivations of people moving to the Hiawatha LRT corridor in the Minneapolis–Saint Paul, Minnesota, metropolitan area and how their preferences factor into location choice. Few differences in residential preferences, except for transit preferences, are found between people moving to the Hiawatha and urban control corridors. Transportation-disadvantaged people and people who prefer transit are more likely to live in a location that is mismatched with their preferences for transit characteristics. Good transit service and job accessibility are important for urban and suburban residents, but affordability and safety dominate location choice. These findings highlight the importance of neighborhood design in addition to rail transit investment

Heterogeneous effects of neighborhood type on commute mode choice: An exploration of residential dissonance in the Twin Cities

Many studies have measured residential and travel preferences to address residential self-selection and they often focused on the average or independent effect of the built environment on travel behavior. However, individuals\u27 behavioral responses to built environment interventions may vary by their different tastes. Using the 2011 data from the Minneapolis–St. Paul metropolitan area, this study examines the influences of neighborhood type, travel attitudes, and their interaction terms on commute mode choice. The interactions between neighborhood type and travel attitudes have no significant impact on driving commute frequency whereas the effects of neighborhood type on the propensity for transit commute differ by transit preference. Specifically, urban consonants (including those in LRT neighborhoods) have the highest propensity for transit commute, followed by suburban dissonants, urban dissonants, and then suburban consonants. Therefore, individuals\u27 heterogeneous responses to built environment elements should be taken into account in future research and in the design of land use and transportation policies aiming to shape urban travel

Exploring causal effects of neighborhood type on walking behavior using stratification on the propensity score

The causality issue has become one of the key questions in the debate over the relationship between the built environment and travel behavior. To ascertain whether changes to the built environment are a cost-effective way to change travel behavior, it is necessary to determine the magnitude of the effect. Further, it is important to understand whether the observed influence of the built environment on travel behavior diminishes substantially once we control for self-selection. Using 1553 residents living in four traditional and four suburban neighborhoods in Northern California, this study explores the causal effect of neighborhood type on walking behavior and the relationship between this effect and the observed influence of neighborhood type on walking behavior. Specifically, propensity score stratification, which has been widely used to reduce selection bias, was applied. The results showed that, on average, the causal influences of neighborhood type are likely to be overstated by 64% for utilitarian walking frequency and 16% for recreational walking frequency, if residential self-selection is not controlled for. However, neighborhood type still plays a more important role in affecting walking behavior than does self-selection. This study also offers a basic tutorial for the propensity score stratification approach and discusses its strengths and weaknesses for applications in the field of land use and travel behavior.

The influence of light rail transit on transit use: An exploration of station area residents along the Hiawatha line in Minneapolis

Rail transit is often implemented in the corridors already with high transit demand. When evaluating their ridership benefits, previous studies often choose the city/county/region as control groups, rather than comparable corridors without rail, and hence overstate their impacts. In this study, we employ propensity score matching to explore the impact of Hiawatha light rail transit (LRT) on transit use. We find that compared to residents in similar urban corridors, the Hiawatha LRT promotes transit use of residents who have lived in the corridor before its opening, and that residents who moved to the corridor after its opening use transit as often as new residents in the comparable urban corridors without LRT. We conclude that besides LRT, land use and transportation policies are necessary for ridership growth

When and How Much Did the Green Line LRT Increase Single-Family Housing Values in St. Paul, Minnesota?

Studies quantifying value added of transit often cannot differentiate whether the premiums are transit effects or location effects. Limited studies have examined the timing of value added. Using before and after data, this study explores the impact of the Green Line LRT on housing sales prices. Compared to the studied period before its funding announcement, its announcement increased housing values by $9.2/sq ft and its commencement increased sales prices by$13.7/sq ft. Further analyses show that housing value appreciation actually occurred after the announcement but before the commencement. Thus, using the right timing of value added is critical for value capture programs and benefit–cost analysis