Mobility Gap Research Articles

The Geography of Intergenerational Mobility in Latin America and the Caribbean

This paper estimates intergenerational mobility in education, using data from 91 censuses in 24 countries in Latin America and the Caribbean spanning over half a century. It measures upward mobility as the likelihood that individuals will complete one educational stage more than their parents (primary education for those whose parents did not finish primary school, or secondary education for those whose parents did not complete secondary school). It measures downward mobility as the likelihood that an individual will fail to complete a level of education (primary or secondary) that their parents did attain. In addition, the paper explores the geography of educational intergenerational mobility using nearly 400 “provinces” and more than 6,000 “districts,” finding substantial cross-country and within-country heterogeneity. It documents a decline in the mobility gap between urban and rural populations with small differences by gender. It also finds that upward mobility is increasing, and downward mobility is decreasing over time. Within countries, the level of mobility correlates closely to the share of the preceding generation that completed primary school. In addition, upward mobility is negatively correlated with distance to the capital and the share of the workforce employed in agriculture but is positively correlated with the share of the workforce employed in industry. The opposite is true of downward mobility. JEL Classification Codes: D63; I24; J62

Influence of Social Context and Gender Gap Awareness on Women’s Mobility on Public Transportation

A gender gap in mobility, although with different levels, exists everywhere. Several factors are linked to this gap, such as females’ daily schedules and duties, economic aspects, or preferences. Women’s personal risk perception and its counterpart, i.e., actual (in)security in the transportation system, are related aspects as well. This research focuses on these last factors and adds a novel perspective: the influence of the social context and its awareness of the gender gap. To this end, a twofold methodological approach was applied to the cities of Barcelona and Budapest. It included the comprehensive evaluation of local policies aimed at closing gender gap in mobility as well as the distribution and analysis of an ad hoc developed survey. The main research findings indicate that harassment on public transportation is associated with general societal gender dynamics and behaviors. Actions taken by local administrations in the pursuit of gender equality in mobility become effective in the medium term, leading to a decrease in severe aggressions. Among these actions, awareness-raising plays a key role. First, women gain self-confidence and increase their own commitment to the cause; second, a snowball effect takes place, causing the rejection of harassment and the fight against it to spread across different social spheres.

Superior P-Type Switching in InSe Nanosheets for Complementary Multifunctional Systems.

van der Waals (vdW) indium selenide (InSe) is receiving attention for its exceptional electron mobility and moderate band gap, enabling various applications. However, the intrinsic n-type behavior of InSe has restricted its use predominantly to n-type devices, constraining its application in complementary integrated microsystems. Here, we show superior ambipolar InSe transistors with vdW bottom contacts, achieving impressive p-type on/off current ratios greater than 109 and Schottky barrier heights approaching the ideal Schottky-Mott limit. By introducing a partially gate-coupled architecture, we also demonstrate an ambipolar-to-unipolar transition and reconfigurable complementary multifunctionality, including n-type and p-type transistors as well as negative and positive rectifiers and breakdown diodes. The rectification polarity and ratio are gate-tunable from 3.5 × 107 down to ∼10 without complex heterostructures, chemical doping, and multigate layouts. The negative and positive breakdowns are reversible, with both the breakdown voltage and switching ratio, which can exceed 108, also being electrically tunable.

Monolayer and bilayer BP as efficient optoelectronic materials in visible and ultraviolet regions

Hexagonal boron phosphide (BP) shows significant promise for optoelectronic applications due to its high carrier mobility and moderate band gap. Strain inevitably occurs during the synthesis of two-dimensional (2D) nanomaterials. In this work, a detailed study on the strain-dependent phonon dispersion and optical properties of monolayer and bilayer BP was performed. The calculated phonon dispersion curves demonstrate that both monolayer and bilayer BP systems remain dynamically stable under tensile strain. By increasing tensile strain, the LO and TO modes soften and the phonon band gap between optical and acoustic modes becomes narrower. The LO and TO modes display expanded phonon spectra under large tensile strains in contrast to the ZA mode. The absorption edge of bilayer BP is located around 0.6 eV, lower in energy with respect to the monolayer BP at ∼ 0.8 eV. The results indicate that the optical absorption may be enhanced by applying the compressive strain. With their broad absorption range and strain-tunable absorption strength and phononic properties, monolayer and bilayer BP are highly promising for next-generation nanodevices.

Advancing Sustainable Transportation Equity for Older Adults: A Geospatial Analysis of Mobility Gaps in Florida

As older adults face increasing mobility challenges due to diminished driving ability, they encounter heightened risks of social exclusion, impacting their mental, social, and physical well-being. This study investigates spatial gaps in the availability of sustainable transportation options—including public transit, paratransit, and specialized senior services—and examines their alignment with the distribution of older adults segmented by age group (65–74, 75–84, and 85+). Using Florida as a case study, Geographic Information System (GIS) was employed to conduct a geospatial analysis, identifying statistically significant clusters of low transportation availability alongside high concentrations of older adults. The primary contribution of this research lies in its innovative methodology, which integrates precise transportation service boundaries with age-segmented demographic data, offering a nuanced assessment of transportation equity as a crucial aspect of sustainability. Findings provide a comprehensive framework for policymakers, enabling targeted resource allocation and planning that enhance mobility, accessibility, and quality of life for older adults. This study contributes to advancing sustainable development goals by addressing transportation disparities, supporting equitable, age-sensitive transportation solutions, and informing broader discussions on sustainable urban planning.

Origin of Oxidation Variations in Ambient-Stable β-InSe.

Understanding and controlling the oxidation of layered materials remain critical issues in the final stages of their practical application in devices. Layered materials achieve a band gap by removing inversion symmetry. However, the oxidation process becomes complex, and the oxidation of these materials is not yet fully understood. As a representative example, InSe has attracted considerable attention due to its high charge mobility and Si-like band gap. However, conflicting observations such as oxidation by Se and In have been reported, including contrasting assessments of the oxidation susceptibility. In this study, we report in situ spectroscopy results detailing the origins of various oxidation pathways. We observed that at low defect densities the reduced reaction barrier of InSe due to Se vacancies leads to oxygen adsorption, while as defects increase, the lower electronegativity of In rises as a new pathway for oxidation. At low defect density, the bulk layer was more energetically favored for oxygen adsorption, allowing oxygen to diffuse to a depth sufficient to form pseudoheterojunctions and making the surface layer seemingly resistant to oxidation. Our results provide an answer to why the resulting diversity of optical responses is expected to increase as well as strategies to achieve gas stability.

Improving the crystallinity of quaternary sputtered CIGS absorber layer properties via optimized deposition and annealing temperature

This study presents a method to improve Cu(In1−xGax)Se2 (CIGS) absorber layer performance through an annealing technique that enhances the quality of as-deposited CIGS films. CIGS films were deposited on soda-lime glass substrates using RF magnetron sputtering at 300 °C, 400 °C, and 500 °C, followed by annealing at 500 °C for 30 min. By annealing, the crystal structure of the CIGS films is aligned, and surface strain is minimized. It can significantly boost the films’ crystallinity, crystallite sizes, carrier concentration, mobility, and energy gap. The highest temperatures enhanced crystallinity due to larger crystallite size, resulting in lower resistivity. The properties improvements are crucial for optimizing CIGS absorber layer performance. Complete CIGS solar cell at 300 °C yield Voc = 253 mV, Jsc = 1.78 mA/cm2, and efficiency = 0.15 %.

Vertical Mobility and Mental Gap of Scheduled Caste Students in West Bengal

This study investigates the complex relationship between vertical mobility and the mental gap experienced by Scheduled Caste (SC) students in West Bengal. Vertical mobility refers to the process by which individuals or groups ascend the social hierarchy, while the mental gap represents psychological barriers that often impede SC students from realizing their full potential. This research aims to elucidate various aspects of vertical mobility, examine the factors contributing to the mental gap experienced by SC students in higher education, and explore strategies to address these challenges to promote both personal development and upward mobility. To accomplish this objective, we employed qualitative documentary analysis and conducted a comprehensive review of existing literature, policy documents, and relevant case studies to gain a deeper understanding of the socioeconomic realities and educational trajectories of SC students. Our findings indicate that vertical mobility encompasses multiple dimensions, including educational attainment, career progression, and diverse social perspectives. Furthermore, we identified key contributors to the mental gap, such as internalized biases, economic constraints, and the pervasive influence of caste consciousness. By elucidating these critical factors, this study sought to propose effective strategies for bridging mental gaps and enhancing upward mobility among SC students. Ultimately, this research aims to contribute to the ongoing discourse surrounding social equity and empowerment for marginalized communities, emphasizing the urgent need for targeted interventions that facilitate the full integration of SC students into mainstream educational and social spheres.

Mobility Gaps of Hydrogenated Amorphous Silicon Related to Hydrogen Concentration and Its Influence on Electrical Performance.

This paper presents a comprehensive study of hydrogenated amorphous silicon (a-Si)-based detectors, utilizing electrical characterization, Raman spectroscopy, photoemission, and inverse photoemission techniques. The unique properties of a-Si have sparked interest in its application for radiation detection in both physics and medicine. Although amorphous silicon (a-Si) is inherently a highly defective material, hydrogenation significantly reduces defect density, enabling its use in radiation detector devices. Spectroscopic measurements provide insights into the intricate relationship between the structure and electronic properties of a-Si, enhancing our understanding of how specific configurations, such as the choice of substrate, can markedly influence detector performance. In this study, we compare the performance of a-Si detectors deposited on two different substrates: crystalline silicon (c-Si) and flexible Kapton. Our findings suggest that detectors deposited on Kapton exhibit reduced sensitivity, despite having comparable noise and leakage current levels to those on crystalline silicon. We hypothesize that this discrepancy may be attributed to the substrate material, differences in film morphology, and/or the alignment of energy levels. Further measurements are planned to substantiate these hypotheses.

Lasting Legacy: The Enduring Relationship Between Racially Restrictive Housing Covenants and Health and Wellbeing.

Racially restrictive covenants in housing deeds, commonplace in Minnesotafor houses built from the 1910s to the 1950s, provided a foundation for the myriad of policies that made it difficult for people of color to obtain housing. Though covenants were ruled illegal in 1968, their legacy continues to shape neighborhoods. The Mapping Prejudice Project's efforts in Hennepin County, Minnesota, produced the first systematic documentation of racially restrictive covenants. We use this novel data set to explore the relationship between historic covenants and current health and wellbeing outcomes. Using regression analysis to control for neighborhood level covariates, we compare previously covenanted neighborhoods to neighborhoods without covenants. Today, previously covenanted neighborhoods have higher life expectancy and lower rates of obesity, diabetes, coronary heart disease, and asthma than neighborhoods without racially restrictive covenants. Additionally, previously covenanted neighborhoods have less upward mobility for children from poorer households, and there are larger gaps in upward mobility between white and Black children. These findings contribute to a growing literature that shows racist policies, even decades after they are legally enforceable, leave an imprint on neighborhoods. Using the novel data from the MappingPrejudiceProject, we provide statistical analysis that confirms qualitative and anecdotal evidence on the role of racial covenants in shaping neighborhoods.

Nitrogen: A promising doping strategy for high-performance ovonic threshold switching selectors

The Ovonic Threshold Switching (OTS) selector serves as an essential component in the development of three-dimensional high-density memory integration technology. Nevertheless, the state-of-the-art high-performance OTS materials usually contain toxic elements such as arsenic (As), posing significant risks to both environmental and human health. Nitrogen (N), which belongs to the same group as arsenic (As), has emerged as a highly promising alternative for As doping. However, the underlying mechanisms that govern N-based OTS materials have not yet been extensively investigated. In this study, we delve into the effects of N doping on the structural, bonding, and electronic properties of amorphous GeSe (a-GeNSe) by ab initio molecular dynamics simulations to bridge the knowledge gap. Our findings indicate that upon N doping in a-GeSe, the formation of robust Ge-N bonds, along with N-centered tetrahedral and triangular structures, resulting in the sluggish atomic movement that enhances the thermal stability and endurance of a-GeNSe. The OTS characteristics are significantly influenced by the material’s electronic band structure, and thus the relatively slow performance drift can be attributed to the stabilization of mid-gap states, a result of N doping which effectively slows down the aging process of chalcogenide glass. Moreover, the increased mobility gap in a-GeNSe raises the threshold voltage (Vth), making it more compatible with commercially available phase-change memory materials. Our findings reveal the extensive impact of the N element on a typical OTS material and offer valuable perspectives for alternative doping strategies that could potentially supplant As practices.

Social sustainability in urban mobility: An approach for policies and urban planning from the Global South

Historically, transportation projects and urban mobility policies overlook the dimension of social sustainability, mainly focusing on economic and environmental criteria. This neglect, seen enhanced in the Global South, leads to long travel times, growing congestion, reliance on motorcycles, high traffic accident rates, and limited access to public transport, jobs, and urban facilities, especially for the more vulnerable population. In light of these issues, this paper proposes the Social Sustainability of Urban Mobility (SSUM) approach as an analytical framework that assesses the state of social sustainability in urban mobility by applying a Systematic Literature Review where three gaps were found. First, by tailoring the SSUM approach to the context of the Global South, it is possible to address the population-focused gap in urban mobility. Second, in the literature review, a theoretical gap defining social sustainability in urban mobility and its three primary categories has yet to reach a consensus among practitioners and academics. Finally, more empirical research should be conducted to discuss methodological aspects of operationalizing the SSUM approach through the three main categories: accessibility, the sustainability of the community, and institutionality. The SSUM approach promotes implementing a sustainable urban agenda that builds inclusive, equitable, and just cities in urban mobility.

A decision support scheme for solving the mobile coverage gap in rural areas in developing countries – Demonstrated with a case in Indonesia

As a primary means of communication, the role of mobile telecommunications networks is important for a developing country's economic and social development. However, especially rural areas in low-income countries still lack mobile coverage. In the academic literature, only segmented solution strategies for this mobile coverage problem in rural areas are proposed. These are either technological, regulatory, or organizational solutions, whereas solving the mobile coverage gap requires an integrated approach to develop arrangements for mobile network rollout in rural areas. This paper presents a comprehensive overview of the causes of the lack of mobile coverage, the available solutions, and how they can be combined. Based on this overview, the paper proposes a decision support scheme for selecting a suitable arrangement for solving the mobile coverage gap. In this decision support scheme, the technical, organizational, and regulatory solutions are combined to develop a set of arrangements that match the local key causes of the lack of mobile coverage and that fit with the local context. In the last phase of the decision support scheme, the relevant stakeholders are involved in selecting the most suitable arrangement. We demonstrate the decision support scheme by applying it to the case of an unserved rural village in Indonesia, Unipa on the island of Papua, to show how it can guide a developing country to initiate the process of developing a solution for mobile coverage problems in rural areas.

Nonvolatile Modulation of Bi2O2Se/Pb(Zr,Ti)O3 Heteroepitaxy.

The pursuit of high-performance electronic devices has driven the research focus toward 2D semiconductors with high electron mobility and suitable band gaps. Previous studies have demonstrated that quasi-2D Bi2O2Se (BOSe) has remarkable physical properties and is a promising candidate for further exploration. Building upon this foundation, the present work introduces a novel concept for achieving nonvolatile and reversible control of BOSe's electronic properties. The approach involves the epitaxial integration of a ferroelectric PbZr0.2Ti0.8O3 (PZT) layer to modify BOSe's band alignment. Within the BOSe/PZT heteroepitaxy, through two opposite ferroelectric polarization states of the PZT layer, we can tune the Fermi level in the BOSe layer. Consequently, this controlled modulation of the electronic structure provides a pathway to manipulate the electrical properties of the BOSe layer and the corresponding devices.

Understanding older adults' travel behaviour and mobility needs during the COVID-19 pandemic through the lens of the hierarchy of travel needs: a systematic review

Abstract The aim of this article is to critically review the scientific literature about the changes in travel behaviour and mobility amongst older adults caused by the COVID-19 pandemic across various countries, identify unmet travel needs and highlight patterns of inequalities in older adults' mobility. We have collected articles from four academic databases: PubMed, Scopus, Transportation Research International Documentation (TRID) and Web of Science. Papers were considered for inclusion if they were published online in 2020 or later, written in English, and referred to urban or rural changes in travel behaviour and mobility of older adults over 50 years old. We examined the pre-existing models developed before the outbreak and classified the articles based on Musselwhite and Haddad's hierarchy of older adults' travel needs. The synthesis of the selected 25 articles shows a general decline in literal mobility amongst older adults, an increased share of virtual travel and their decreased capacity to fulfil different levels of travel needs. Findings also indicate an increased gap in older adults' mobility across geographical regions with various levels of transport infrastructure and digital capital. We conclude the paper with the lessons learned, the opportunities ahead, and the challenges that must be overcome to achieve sustainable development and the United Nations Decades of Healthy Ageing goals in the post-pandemic world.

Compromise Design of Resonant Levels in GeTe‐Based Alloys with Enhanced Thermoelectric Performance

AbstractResonant levels (RLs) are expected to increase the density of states (DOS) abruptly, thereby increasing the Seebeck coefficient for a high thermoelectric figure of merit (ZT). However, the negative effects of RLs on reducing the carrier mobility and band gap have rarely been explored. In this work, the pros and cons of resonant‐state doping of group IIIA elements (In, Ga) in GeTe‐based alloys are studied by experimental transport properties and density‐functional‐theory calculations. RLs effects of Fermi level pinning and increased effective mass are strong in Ge0.9‐xInxSb0.1Te but weak in Ge0.9‐y(In0.5Ga0.5)ySb0.1Te, which shows dependence on the hump DOS relative to the background, location of RLs, and energy width of RLs. Using the In‐Ga co‐doping strategy to make a compromise between the DOS, carrier mobility, and bipolar transport, combined with beneficial alloying effects of Pb and Sb, a peak ZT≈ 2.1 at 773 K and a high average ZT≈ 1.43 within 300–773 K can be obtained in Ge0.78In0.005Ga0.005Pb0.1Sb0.07Te. The corresponding single‐leg device shows a remarkable energy conversion efficiency of 13.7% at a temperature difference of 451 K. This work suggests that RLs are not always beneficial for improving ZT, and the compromise design of RLs should be carefully considered to advance ZT.

Unveiling the potential of vanadium-doped CVD-grown p-type MoS2 in vertical homojunction UV–Vis photodiodes

2D materials are a popular choice for the fabrication of p-n diodes for applications in integrated optoelectronics owing to their outstanding properties such as strong light-matter interactions, high mobility, and tunable band gap. The synthesis of monolayer and few-layer 2D materials with both p-type and n-type behavior is thus essential for the design and fabrication of such devices. However, the large-scale direct synthesis of p-type 2D materials is still a challenge as most of these materials are either n-type or ambipolar. Here, we report the successful synthesis of large-area, p-type MoS2 layers doped with vanadium on SiO2/Si substrates, achieving flake sizes >100 μm. By varying the concentration of the vanadium precursor, we precisely controlled the doping level, achieving vanadium atomic percentages ranging from 0.70 % to 1.57 %. Back gate field-effect transistors (FETs) were fabricated, enabling the tuning of device characteristics to exhibit ambipolar or p-type behavior. Moreover, a vertical p-n MoS2 homojunction was fabricated for rectification and optoelectronic applications, demonstrating a high responsivity of up to 978.1 A/W and a specific detectivity (D*) of 1.06 × 1012 Jones at λ = 365 nm with varied powers of the incident light source. This work demonstrates the role of vanadium as a dopant for tunable electrical transport behavior as well as for the fabrication of a photodiode, which can be used for high-performance optoelectronic devices in the future.

The parental role in intergenerational educational persistence: an empirical investigation with cross-country panel data

PurposeThe main aim of this study is to investigate the role of fathers and mothers in the intergenerational educational persistence for sons and daughters under two dimensions that characterize the clusters of countries: redistributive policy and governance.Design/methodology/approachData from the Global Database of Intergenerational Mobility (GDIM), hierarchical cluster analysis on principal components and panel regression are used in this study to estimate intergenerational educational correlation and to investigate its determinants related to the parents’ and descendants’ education variables in 93 countries grouped in four clusters. The empirical analysis is differentiated by gender combinations of parents and descendants.FindingsIn the clusters of countries characterized by high inequalities and poor governance, our findings show that the role of the fathers is stronger than that of the mothers in educational transmission; fathers and mothers are more influential for the daughters rather than for the sons; parental educational privilege is the main driver of intergenerational educational persistence; there is an inverse U-curve in the association between educational inequality of the parents and educational correlation for the sons. Differently, in the countries characterized by high income, low redistributive conflict and better governance, the role of the mothers is stronger and education mobility for the daughters is higher than that for the sons.Social implicationsThe authors’ results remark on the importance of social welfare policies aimed to expand a meritocratic public education system including schooling transfers for lower social class students and narrowing the gender gap in educational mobility between daughters and sons. Social welfare policies should also be oriented to spread high quality child care systems that help to foster greater women equality in the labor market, because the strength of educational persistence depends on the position of the mother in the economic hierarchy.Originality/valueThe distinctiveness of the paper can be found in the fact that this study investigates the parental role differentiating by gender and coupling hierarchical cluster analysis on principal components with panel regression models. This allows us to have a sample of 93 countries aggregated in four groups defined in two dimensions: redistributive policy and governance. Amongst the determinants of educational transmission, we consider not only education’s years of the parents but also other determinants, such as educational inequality and privilege of the parents. We also identify the effects of investment in human capital and educational inequalities for the descendants on education mobility.

Creating an Informal Transport Route

Problem, research strategy, and findings This study shares the results of a test I established of a new minibus route in Kampala with the Uganda Transport Operators Federation (UTOF). Informal transport provides the bulk of urban mobility in the Global South but may be limited in the connectivity and spatial coverage it is able to provide. I tested the effectiveness of market response by temporarily subsidizing operations in an unserved location and found that even a limited expansion of routing found passenger demand, showing a countercurrent of travel against the existing pattern of radial, central business district–to-suburb travel. Female street vendors were a particularly important previously unserved group of passengers. For operators, the study revealed that establishing new services can be difficult, requiring organizational capacity and substantial investment and risk in terms of time and money. In parallel, when such investments are made, other formal and informal actors, such as police, government bureaucracy, and competing operators, can act to extract the benefits, further slowing the change and growth of the transport network. Takeaway for practice I describe the implementation steps and lessons learned from a small-scale pilot project that could be scaled for use as a planning intervention as well as to assess the equity of market-driven public transport and identify mobility gaps. This study expands the body of evidence on the effectiveness of informal transport systems for diverse mobility needs and spatial coverage, providing unique data and a methodological approach to address latent and hidden mobility needs for urban residents. It develops a potential avenue of intervention for regulators and planning practitioners for a cheap, light-touch intervention that collaborates with informal transport workers to expand accessibility and equity for passengers.

Excited State Regulated Emission in Hybrid Indium Halides via Crystal Structure Switch.

Organic-inorganic metal halides have become one of the most promising materials in the next generation of optoelectronic applications due to their high charge carrier mobility and tunable band gaps. In this study, Sb:PA6InCl9 and Sb:PA4NaInCl8 single crystals were prepared through evaporation crystallization, respectively. Due to the different degrees of lattice distortions, the highly efficient yellow emission in Sb:PA6InCl9 at 610 nm and the green emission in Sb:PA4NaInCl8 at 545 nm were achieved by regulation of the excited state, respectively. By introducing additional sodium ions in the post-treatment, we found that the zero-dimensional Sb:PA6InCl9 could rapidly convert into a two-dimensional layered structure of Sb:PA4NaInCl8, thus resulting in a novel green/yellow emission switch. This work guides the structural and performance control of organic-inorganic hybrid In-based metal halides and offers broad prospects for luminescent switching in anticounterfeiting applications.