Mobility Gap Research Articles

Autonomous vehicles and mobility for people with special needs

Large mobility gaps exist between people with and without disabilities. People with special needs are heavily dependent upon public transportation for their essential needs. Autonomous vehicles (AVs) have the potential to increase mobility for these populations. However, they have been largely absent from AV perception research. To fill this gap, we analyzed their perceptions, willingness to use, and concerns over autonomous public transit (APT) based on an on-board intercept survey of 1861 current bus riders in Michigan, with 40% having some type of special needs. We found significant differences among different special needs groups. While respondents who were visually impaired, mobility restricted, or with multiple accommodation needs were more likely to rely on public transit than those without any special needs, their willingness to use APT varied. Respondents with visual impairment were more likely, but riders with mobility disabilities were less likely to be willing to use APT. In addition, our survey results suggest that respondents with special needs perceive AVs primarily negatively. This was especially true for mobility-restricted groups. Furthermore, there were differences in bus riders’ reasons not to use APT. Compared to respondents without special needs, those with multiple accommodation needs hold concerns over APT’s safety more, while respondents with mobility disabilities were more likely to distrust AV technology. This study advances our understanding of different special needs populations’ perception and acceptance of APT, providing support to policymakers in developing inclusive policies and practices that would bring the promised benefits of AVs to these populations.

A novel reconfigurable spherical joint based on linear independence of screws and its resultant metamorphic mechanisms

This paper presents a novel reconfigurable spherical (rS) joint resulting from the line dependence of screws and their embodiment geometry. Subsequently, the structure and phase change of the rS joint are elaborated. With this new invention, two novel metamorphic mechanisms, that are, the Schatz-derived metamorphic mechanism and the R(rS)R-R(rS)R metamorphic mechanism, are obtained by inserting the rS joint. The mechanisms entail a reconfiguration process that occurs in two manners: the phase change of the rS joint and the bifurcation of the mechanism. The Schatz-derived metamorphic mechanism entails reconfiguration by phase change of the rS joint and the bifurcation, the R(rS)R-R(rS)R metamorphic mechanism reconfigures the configuration based on phase change of the two rS joints. Remarkably, the former realizes the switch between two assembly configurations without resorting to disassembly and reassembly, and maintains the characteristics of the original Schatz mechanism while the rS joint situates in phase R. The latter changes the mobility and bridges gap between a spatial single-loop mechanism and a structure. With this new reconfigurable joint, various reconfigurable mechanisms could be generated by inserting the reconfigurable joint into the classical ones.

Shorter commutes, but for whom? Comparing the distributional effects of Bus Rapid Transit on commute times in Cape Town, South Africa, and Barranquilla, Colombia

Bus rapid transit has become an increasingly popular investment in cities in the Global South, where policy discourse often positions BRT as a pro-poor investment. Planners usually expect BRT to reduce commute times in urban areas, particularly for economically disadvantaged populations, thus reducing mobility gaps between transit users across different socioeconomic population groups. Despite increased interest in BRT, there is surprisingly limited research testing these assumptions. Using data from a retrospective survey administered in Barranquilla, Colombia, and Cape Town, South Africa, we investigated whether BRT contributes to reducing commute time gaps between socioeconomic populations. Our comparative and distributional analyses indicate that, while BRT narrowed the gap in commute times in Cape Town, it did not contribute to closing the gap in Barranquilla. We argue that this contradiction may, in part, be explained by the degree to which BRT route configuration responded to the urban form and pre-BRT transit conditions in each city—two factors often overlooked in academic literature and discussions surrounding BRT planning. We close by providing policy recommendations that promote more equitable planning practices and recognize the links between transport and land uses in the Global South urban context.

Women in Transport Research and Innovation: A European Perspective

Several gender differences exist in the transport sector. These include accessibility to transport modes, safety and security when travelling, and the participation of women in transport research and innovation (R&I). In order to achieve sustainable and inclusive transport, planners and policymakers should consider all impacts on gender equality. This paper sheds light on two main issues which interconnect through the decision-making process. The first relates to women’s behaviour in the transport system (i.e., studies the gender mobility gap). The second concerns the role of women in transport R&I, particularly the topics covered by research projects and relevant descriptive statistics of their participation in the sector. Based on a literature review, this paper identifies critical issues in the European transport sector and key European Union policy initiatives and regulations that address gender equality and transport. The European Commission’s Transport Research and Innovation Monitoring and Information System (TRIMIS) is used to summarise the status and evolution of European research in addressing women’s issues in transport. It also analyses the participation of women in European transport research and innovation activities. The paper assesses progress to date and identifies challenges and opportunities for women, mobility, and transport. It concludes by providing policy recommendations to overcome the major barriers to gender equality in the European transport sector and to transport research and innovation.

Development of a novel methyl germanane modified disposable sensor and its application for voltammetric phenol detection

Germanane is a novel 2D material and a good candidate for electrochemical applications due to it has high electron mobility and direct band gap. Methyl germanane (m-GMN) is a covalently terminated germanane and has superior catalytic activity, electron mobility and stability. Herein, m-GMN modified chemically activated pencil graphite electrodes (m-GMN/c-PGEs) were developed and m-GMN/c-PGEs were utilized for voltammetric detection of phenol (PNL). Chemical activation of PGEs (c-PGEs) was firstly performed, then m-GMN was modified at the surface of c-PGEs. Electrochemical and microscopic characterizations of m-GMN/c-PGEs were performed. The detection limits (LODs) were estimated as 0.72 µg/mL (7.65 µM) and 0.35 µg/mL (3.72 µM) using c-PGEs and m-GMN/c-PGEs, respectively. Application of the sensor was tested in water samples and the selectivity of the sensor system was tested against Cu2+, Hg2+, 2,4-dichlorophenoxyacetic acid, 2,6-di-tert-butyl-4-methylphenol, D(+)glucose and paracetamol. A novel electrochemical sensor which had crucial properties such as being reproducible, repeatable, and stable was developed for PNL detection by the development of m-GMN/c-PGEs.

III-V-on-Si transistor technologies: Performance boosters and integration

In this work, we review progress in III-V transistor technologies. Key approaches for silicon integration are described, with a distinction being made between large area layer transfer and selective growth techniques. We show how the integration approach must be tailored for the intended application to maximize performance, functionality and minimize cost. We also highlight performance boosters such as heterostructure channel stacks, which offer increased carrier mobility towards improved RF and RF-CMOS performance. Recent progress in tunneling field-effect transistors (TFETs) have enabled the TFET architecture as a process module, allowing for dense integration with MOSFETs on the same chip towards an extremely low-power CMOS technology. Finally, we highlight emerging applications for III-V devices at cryogenic temperatures, where there is a rising need for low-power electronics to support the scaling of quantum computers. The unique properties of III-V, their high mobility and band gap engineering make them highly suitable for this application.

Simulation of hydrogenated amorphous silicon: temperature dependence of nonequilibrium distribution functions for trap states

Nonequilibrium distribution functions (NDFs) for trap states in the mobility gap under photoillumination and zero bias voltage are derived by a constructed self-consistent drift–diffusion simulator consisting of the Poisson equation and current continuity equations for hydrogenated amorphous silicon (a-Si:H). Regarding the temperature dependence of the NDF, we find that the values of the NDF decrease with increasing temperature (negative temperature dependence) in the energy region near the conduction band for p-type a-Si:H. This is the reverse of the temperature dependence of the equilibrium distribution functions (EDFs) for the trap states in the mobility gap. Furthermore, we show that this new physical characteristic can be applied in explaining the temperature characteristic of the photoconductivity caused by electron hopping in the conduction band tail for a-Si:H. The photoconductivity of a-Si:H decreases with increasing temperature, which is called thermal quenching (TQ). We show that the TQ observed at low temperatures of approximately 200 K for p-type a-Si:H can be explained by the electron hopping model, with the p-type NDF having a negative temperature dependence.

Using Longitudinal Data to Explore the Gender Gap for Academic Economists

There are widespread gender inequities within the economics discipline. In this paper, we collect and analyze new longitudinal salary and personnel data from top economics departments at public institutions. A panel spanning 2005 to 2018 allows us to follow individuals and facilitates the examination of gender gaps in career progression, salary growth, and mobility. Using these data, we document the growth of salary gender gaps with the length of time in the profession, emerging roughly 10 years after the start of one's career. Some of these gaps are attributable to women moving through academic ranks more slowly than men.

The mobility gap: estimating mobility thresholds required to control SARS-CoV-2 in Canada.

BACKGROUND:Nonpharmaceutical interventions remain the primary means of controlling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) until vaccination coverage is sufficient to achieve herd immunity. We used anonymized smartphone mobility measures to quantify the mobility level needed to control SARS-CoV-2 (i.e., mobility threshold), and the difference relative to the observed mobility level (i.e., mobility gap).METHODS:We conducted a time-series study of the weekly incidence of SARS-CoV-2 in Canada from Mar. 15, 2020, to Mar. 6, 2021. The outcome was weekly growth rate, defined as the ratio of cases in a given week versus the previous week. We evaluated the effects of average time spent outside the home in the previous 3 weeks using a log-normal regression model, accounting for province, week and mean temperature. We calculated the SARS-CoV-2 mobility threshold and gap.RESULTS:Across the 51-week study period, a total of 888 751 people were infected with SARS-CoV-2. Each 10% increase in the mobility gap was associated with a 25% increase in the SARS-CoV-2 weekly case growth rate (ratio 1.25, 95% confidence interval 1.20–1.29). Compared to the prepandemic baseline mobility of 100%, the mobility threshold was highest in the summer (69%; interquartile range [IQR] 67%–70%), and dropped to 54% in winter 2021 (IQR 52%–55%); a mobility gap was present in Canada from July 2020 until the last week of December 2020.INTERPRETATION:Mobility strongly and consistently predicts weekly case growth, and low levels of mobility are needed to control SARS-CoV-2 through spring 2021. Mobility measures from anonymized smartphone data can be used to guide provincial and regional loosening and tightening of physical distancing measures.

Electronic Structure Modification of Rectangular Phosphorene Quantum Dots Via Edge Passivation

Phosphorene is an elemental two-dimensional material that shows great promise as a metal-free photocatalyst owing to its high carrier mobility and direct band gap. Doping and edge functionalization...

Challenges and Strategies for Post-COVID-19 Gender Equity and Sustainable Mobility

The COVID-19 pandemic has forced countries around the world to take unprecedented measures to contain it. In particular, its impact on mobility has been enormous, causing a sudden decrease in the number of trips and changes in the choice and use of modes of transport. Furthermore, the effects of this health crisis on the social and economic spheres have aggravated inequalities between population groups, with women being one of the most affected groups, which may accentuate the already known gender gap in mobility. Based on these premises, we carried out a strategic analysis of urban mobility from the perspective of sustainability and gender equity in the context of the pandemic, identifying a set of effective strategies to address the post-COVID-19 urban mobility scenario. To this end, based on the review of the literature and expert opinions, we carried out a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis that allowed us to formulate 16 strategies after careful consideration of the weaknesses, strengths, threats and opportunities encountered. Our results provide useful recommendations for making successful policy decisions on post-COVID-19 mobility planning towards a more sustainable, equitable and safe model.

The role of gender and living context in shaping Palestinian children’s agency and well-being

Through a mixed-method design, the study investigated gender and context differences within the domains of agency, life satisfaction, affectivity, and symptoms of trauma. Two-hundred-fifty Palestinian children from cities, villages, and refugee camps (M = 11.58, SD = 1.49) completed four self-reported measures, Multilevel Student’s Life Satisfaction Scale, Children’s Hope Scale, Children’s Impact of Event Scale, and Positive and Negative Affect Scales. Based on drawings and walk-along interviews with 75 children (M = 10.27, SD = 1.38), thematic analysis was performed to detect gender and context-specific differences regarding all the variables, which assisted in the interpretation of quantitative findings. Findings showed higher girls’ satisfaction in the dimension of school (MD = 1.497, p< .05) and higher values of negative affect (MD = 1.192, p< .05). Correlation analysis revealed that older girls displayed lower levels of life satisfaction, positive emotions, arousal symptoms, and agency (p< .05). Children living in the West Bank reported higher levels of agency (MD = 1.898, p< .05) in comparison to those in Gaza. The comparison of urban, rural, and refugee camp participants yielded significant differences concerning children’s satisfaction with their lives (MSLSS: F (2, 245) = 10.69, p < .001) and positive emotions (F (2, 245) = 6.49, p = .002). Six themes emerged from the TA: girls’ feelings of insecurity and uncertainty; gender gaps in mobility and accessibility to public spaces; education as a mean for equal rights; perceived gender inequality; environmental unpredictability in the context of Gaza; unstable social and environmental conditions in the refugee camps. We explored participants’ strategies of resistance to endure adverse living conditions.

Physical, linear and nonlinear optical properties of amorphous Se90-xTe10Mx (M = Zn, In, Pb, x = 0, 5) chalcogenide thin films by electron-beam deposition

Amorphous Se90Te10 and Se85Te10M5 (M= Zn, In, Pb) were deposited as thin films on glass substrates by electron-beam evaporation. The effect of Zn, In and Pb incorporated at the expense of Se on optical and physical properties of chalcogenide Se90Te10 were investigated and results were correlated. The transmission and reflectance spectra of the samples were used to deduce some dispersive linear optical constants which were studied from 250 to 2500 nm. The optical gap was evaluated through extrapolation of the Tauc plot in the strongly absorbing region and based on the Wemple-DiDomenico single oscillator model. Ideas from the chemical bond approach and consideration of disorders emanating from localized states in the mobility gap were employed to explain the optical trends. Some dielectric and nonlinear optical parameters including nonlinear refractive index and susceptibility of the thin films were calculated.

Possibilities and Limits of Decreasing the Gap of Anatase TiO2 by Alloying with Nitrogen

Nitrogen doping has been suggested to increase the photocatalytic activity of titanium dioxide in the visible. For this purpose, narrowing of the mobility gap (the gap between conductive states) wo...

The gender gap in intergenerational mobility

This paper employs mobility matrices, univariate regressions and multivariate econometric techniques based on the recently published Brazilian National Household Sampling Survey to investigate the relevance of the gendered patterns in the intergenerational transmission of educational attainment. The empirical evidence from these three different approaches is absolutely unanimous: In Brazil there is a significant variation in degree of mobility across genders, with a higher mobility level for daughters than for sons. The reason for this gender gap in mobility lies in the chances of attaining the educational levels: regardless of the educational background of the parents, females have a lower chance of remaining without school certificate and a greater probability to achieve a tertiary education. This study has demonstrated also that the educational attainment of children is strongly associated with the education of their most educated parent, regardless of their gender and this correlation is higher for female than for male.

The Geography of Intergenerational Mobility in Latin America and the Caribbean

In this paper, I estimate intergenerational mobility (IGM) in education using cross-sectional data from 91 censuses that span 24 countries in Latin America and the Caribbean (LAC) over half a century. I measure upward mobility as the likelihood of obtaining at least a primary education for individuals whose parents did not finish primary school, whereas downward mobility as the likelihood of failing to complete primary education for individuals whose parents completed at least primary school. In addition, I explore the geography of educational IGM using nearly 400 “provinces” (coarse administrative units similar to states in the U.S.) and more than 6,000 “districts” (fine administrative units similar to counties in the U.S.). I document wide cross-country and within-country heterogeneity. In LAC, the distance between the most and least upwardly mobile country is close to what has been recently documented in Africa, although the least mobile countries in Africa are less mobile than the least mobile in LAC. I document a declining trend in the mobility gap between urban and rural populations, but I do not find important differences by gender. Within countries, the level of mobility is highly correlated to the share of primary completion of the previous generation, which suggests a high level of inertia. In addition, upward (downward) mobility is negatively (positively) correlated to distance to the capital and the share of employment in agriculture, but positively (negatively) correlated to the share of employment in industry.

Is Gender Destiny? Gender Bias and Intergenerational Educational Mobility in India

Many recent studies provide evidence of gender bias against girls in India, for example, in health, education expenditure, breast feeding, and sex selection. In contrast, the gender gap in schooling has narrowed substantially over the decades. Does gender convergence in schooling attainment imply that the girls in the younger generation in India enjoy equal educational opportunities as the boys? To analyze this question, we study intergenerational schooling persistence addressing both empirical and theoretical challenges. We incorporate gender bias against girls in the family, school and labor market in a Becker-Tomes model and derive mobility and investment equations that can be taken to data. Parents may underestimate a girl's ability, expect lower returns, and assign lower welfare weights (“pure son preference”). The model delivers the widely used linear conditional expectation function (CEF) for mobility under constant returns but generates strong predictions: parental bias cannot cause gender gap in relative mobility. With diminishing returns, the CEF is concave, and parental bias affects both relative and absolute mobility. Since coresidency causes severe underestimation of the gender gap, we use data from India Human Development Survey that includes nonresident children and parents. Evidence rejects the linear mobility CEF in favor of a concave relation (both rural and urban). The daughters of uneducated fathers face lower relative and absolute mobility irrespective of rural/urban location. We find gender equality in absolute mobility for the children of college educated fathers in urban areas, but not in villages. Theoretical insights help understand the mechanisms, suggesting underestimation of academic ability and unfavorable school environment for girls. Rural parents exhibit pure son preference. Differences in the incidence of unwanted girls and the impact of parental nonfinancial inputs explain the rural-urban differences. The standard linear model misses important heterogeneity and yields misleading conclusions such as no son preference in rural India.

Reparations and Persistent Racial Wealth Gaps

Reparations is a policy proposal aiming to address the wealth gap between Black and White households. We provide a first formal analysis of the economics of reparations using a long-run model of heterogeneous dynasties with an occupational choice and bequests. Our innovation is to introduce endogenous dispersion of beliefs about risky returns, reflecting differences in dynasties' experiences with entrepreneurship over time. Feeding the exclusion of Black dynasties from labor and capital markets as driving force, the model quantitatively reproduces current and historical racial gaps in wealth, income, entrepreneurship, mobility, and beliefs about risky returns. We use the model to evaluate reparations and find that transfers eliminating the racial gap in average wealth today do not lead to wealth convergence in the long run. The logic is that century-long exclusions lead Black dynasties to enter into reparations with pessimistic beliefs about risky returns and to forego investment opportunities. We conclude by showing that entrepreneurial subsidies are more effective than wealth transfers in achieving racial wealth convergence in the long run.

A new two-dimensional all-sp3 carbon allotrope with an indirect band gap and superior carrier mobility.

The success of fascinating graphene has motivated much interest in exploiting new two-dimensional (2D) carbon allotropes with excellent electronic and mechanical properties such as graphdiyne and penta-graphene. However, there are only very few reported structures for stable 2D all-sp3 carbon allotropes. Here, we proposed a new 2D all-sp3 carbon allotrope, named as TTH-carbon. Using first-principles calculations, we investigated its structure, stability, elastic constants, band structure, carrier mobility and optical properties. The results show that it exhibits good stability. Meanwhile, it possesses a total monolayer thickness of 1.35 Å and an indirect band gap of 3.23 eV, comparable to those of well-known penta-graphene (1.20 Å and 3.25 eV). The calculated mechanical and optical properties of TTH-carbon strongly depend on the crystal orientation. The mobilities of electrons and holes along the y direction are ∼3000 cm2 V-1 s-1, which are ten times of its carrier mobilities along the x direction and three times of that of black phosphorus (∼1000 cm2 V-1 s-1). The proposed structure richens the 2D all-sp3 carbon allotropes and its properties make it a promising material for nanoelectronic and photoelectronic devices.

Electrical resistivity and thermopower of hole-doped delafossite CuCoO2 polycrystals

We have synthesized the polycrystalline samples of the delafossite oxide CuCo1−y Mg y O2 through the thermal decomposition of copper–cobalt–magnesium hydroxycarbonates. As is expected from the theoretical calculations, relatively large thermopower of S ∼ 700 μV K−1 is observed at room temperature in the parent compound CuCoO2, whereas the resistivity is too high even in the doped compounds compared with other thermoelectric oxides. The high-temperature transport is thermal-activation type characterized by two energy gaps, Δ ρ and Δ S , which are estimated from the resistivity and the thermopower, respectively. In the parent compound, we obtain Δ ρ ≃ 0.47 eV and Δ S ≃ 0.38 eV. We find that Δ ρ is larger than Δ S in all the samples, implying a mobility gap opening due to a grain-boundary scattering.