Upper mantle electrical resistivity structure beneath the Southwest Indian Ridge 37ºE

第3回極域科学シンポジウム/第32回極域地学シンポジウム 11月30日（金） 国立極地研究所 ３階ラウン

Framing safety of women in public transport: A media discourse analysis of sexual harassment cases in Bangladesh

This paper analyzes the role of print media in framing incidences of sexual harassment in public transport; particularly in the context of Bangladesh, where gender-based violence is highly prevalent in the public sphere. This article uses Douglas’ cultural theory to reflect on media practices and its institutional power to reframe the social problem through risk and blame attribution. We conducted a discourse analysis of 71 news articles extracted from four of the widely circulated and influential newspapers of Bangladesh. Our findings reveal that the hegemonic discourse of gender-based violence in public transport is systemic and/or primarily reliant on legal recourse. By contrast, discourses presenting sexual harassment as symptomatic of broader gender inequality is less frequent. Moreover, these media platforms belong to an assemblage of patriarchal social-power holders that collaborate with established law and order to facilitate a blame game, thereby relieving the same stakeholders of ownership and accountability. Given the power of news media in constructing meta-narratives of safety (and nudging policymakers), journalists must tread responsibly on issues of blame, women’s safety, and their rights to the city

Riding the change: Exploring women’s navigation of risk and respectability through two-wheeler mobility in Dhaka

This paper sheds light on the understudied phenomenon of female two-wheeler riders in Bangladesh, and their everyday negotiations of moto-mobility in patriarchal public spaces. In transportation research, female riders have traditionally been characterized as occupying the pillion seat. By conducting ethnographic observations of two-wheeler training clubs in Bangladesh (Dhaka) and qualitative interviews with female riders, the paper expands the discussion of gender and mobility beyond the usual focus on car and public transport in the Global South, which is critical for planning equitable and inclusive transport policies. Using the motility framework (access, competence and appropriation), this paper unravels the cultural, spatial and social dynamics of women's everyday moto-mobility. Through engagement in women-only training clubs which also serve as gendered social spaces, female riders actively build technical and spatial competence. They opt for safety-conscious approaches in driving behaviour, subverting traditional/masculine notions of dominance and authority. The findings also reveal how young riders subvert families and communities to acquire and ride motorbikes, but still largely conform (and adapt) to social norms to manufacture respectability (following normative sartorial choices, sex-segregated seclusion/purdah). In other words, their resistance is in proportion to how much they can assert themselves without facing negative repercussions from communities and society at large. As their presence and performances of micro-subversions rewrite spatial geographies (of risk and respectability), this has implications for reshaping the everyday transport geographies of women in urban public spaces. By presenting gender scripts as an element of appropriation in the constant negotiation of mobility, this paper contextualises motility in a non-western setting, and shows how multiple (seemingly contradictory) gender performances can feed into each other and regroup to facilitate women's access (to mobility) and rights in a gendered city

Affects and assemblages of (un)safety among female bus commuters in Dhaka

By examining the lived experiences of 30 female bus commuters in Dhaka using in-depth qualitative approaches, this paper argues for an enhanced understanding of socio-cognitive undercurrents of gendered mobilities. By privileging a feminist-affective lens, and tracing the emotionally and politically charged everyday negotiations of space, power struggles, (dis) comfort, and encounters between gendered bodies, the paper contends that women’s agency to act and respond to harassment in public transport is contingent on multi-scalar assemblages comprising socio-technical infrastructures, lifestyles, cultural histories, personal dispositions and situated knowledge. Moreover, by applying assemblage thinking and affect theories in transport spaces, the study links discussions on gender, violence and mobility beyond the common economic tropes as is common in transport studies of the Global South

Characterization of the in situ magnetic architecture of oceanic crust (Hess Deep) using near-source vector magnetic data

Marine magnetic anomalies are a powerful tool for detecting geomagnetic polarity reversals, lithological boundaries, topographic contrasts, and alteration fronts in the oceanic lithosphere. Our aim here is to detect lithological contacts in fast-spreading lower crust and shallow mantle by characterizing magnetic anomalies and investigating their origins. We conducted a high-resolution, near-bottom, vector magnetic survey of crust exposed in the Hess Deep “tectonic window” using the remotely operated vehicle (ROV) Isis during RRS James Cook cruise JC21 in 2008. Hess Deep is located at the western tip of the propagating rift of the Cocos-Nazca plate boundary near the East Pacific Rise (EPR) (2°15′N, 101°30′W). ROV Isis collected high-resolution bathymetry and near-bottom magnetic data as well as seafloor samples to determine the in situ lithostratigraphy and internal structure of a section of EPR lower crust and mantle exposed on the steep (~20°dipping) south facing slope just north of the Hess Deep nadir. Ten magnetic profiles were collected up the slope using a three-axis fluxgate magnetometer mounted on ROV Isis. We develop and extend the vertical magnetic profile (VMP) approach of Tivey (1996) by incorporating, for the first time, a three-dimensional vector analysis, leading to what we here termed as “vector vertical magnetic profiling” approach. We calculate the source magnetization distribution, the deviation from two dimensionality, and the strike of magnetic boundaries using both the total field Fourier-transform inversion approach and a modified differential vector magnetic analysis. Overall, coherent, long-wavelength total field anomalies are present with a strong magnetization contrast between the upper and lower parts of the slope. The total field anomalies indicate a coherently magnetized source at depth. The upper part of the slope is weakly magnetized and magnetic structure follows the underlying slope morphology, including a “bench” and lobe-shaped steps, imaged by microbathymetry. The lower part of the slope is strongly magnetized, with a gradual reduction in amplitude from east to west across the slope. Surface morphology and recent drilling results indicate that the slope has been affected by mass wasting, but the observation of internally coherent magnetization distributions within the upper and lower slopes suggest that the disturbance is surficial. We attribute the spatial differences in magnetization distribution to the combination of changes in in situ lithology and depth to the source. These survey lines document the first magnetic profiles that capture the gabbro-ultramafic and possibly dike-gabbro boundaries in fast-spreading lower crust

Devising gender-responsive transport policies in South Asia: Gender & Development

Over time, the transport sector has grown more cognisant of gender differences in planning and policy. Yet, extant literature on transport shows that challenges, such as sexual harassment of women still prevail. The value of this study is its contribution towards gender-responsive transport policies with a focus on women by highlighting (1) the spectrum of barriers that prevent women’s mobility across origin to destination journeys; and (2) construction of safety by using interventions and tools available to them, namely technology, women-only solutions, and infrastructural design. The findings are based on data from in-depth interviews with women participants in two Indian cities–Delhi and Kolkata. Drawing from our research, key policy suggestions include framing interventions in a rights-based manner, institutionalising gender-disaggregated data to inform interventions, and sensitising institutions such as the law enforcement on gender equity and women’s rights to the city. This research would be especially beneficial for regions in and beyond South Asia sharing similar contexts

Source of oceanic magnetic anomalies and the geomagnetic polarity time scale

Marine magnetic anomalies provide the framework for the geomagnetic polarity timescale for the Late Jurassic to Recent (since 160 Ma). Magnetostratigraphic records confirm that the polarity reversal sequence interpreted from magnetic anomalies is complete to a resolution of better than 30 ky. In addition to this record of polarity reversals, magnetic anomalies also appear to preserve information on geomagnetic intensity fluctuations. The correspondence of coherent near-bottom anomaly variations with independent estimates of field intensity provides strong evidence that geomagnetic intensity modulates the magnetization of the ocean crust. Indeed, many short wavelength anomaly variations in sea-surface magnetic profiles over fast-spreading ridges are likely attributable to geomagnetic intensity variations. Although longer-term geomagnetic field behavior may also be reflected in anomaly amplitudes, documenting such a signal requires a better understanding of time-dependent changes in the magnetic source (e.g., from low-temperature alteration) that may also affect magnetic anomalies. The extrusive layer, with an average remanence of ∼ 5 A m−1, is the largest contributor to magnetic anomalies. However, enhanced sampling of oceanic gabbros (average remanence ∼ 1 A m−1) and, to a lesser extent, dikes (average remanence ∼ 2 A m−1) reveals that these deeper (and thicker) layers likely generate anomalies comparable to those from the lavas. Lava accumulation at intermediate- and fast-spreading ridges typically occurs over a narrow (1–3 km) region and dike emplacement is even more narrowly confined, resulting in a relatively high fidelity record of geomagnetic field behavior. The slow cooling of the gabbroic layer, however, results in gently dipping polarity boundaries that significantly affect the skewness of the resulting anomalies, which is also a sensitive measure of net rotations of the source layer(s). The magnetizations of the dikes and gabbros are characterized by high stability and are not expected to significantly change with time, although there are insufficient data to confirm this. The lavas, however, typically show evidence of low-temperature alteration, which has been long regarded as a process that progressively reduces the magnetization (and degrades the geomagnetic signal) in the extrusive layer and reduces the amplitude of magnetic anomalies. Sufficient data have become available to examine this conventional wisdom. There is a substantial (∼ 4x) reduction in magnetization from on-axis samples to immediately off-axis drillsites (∼ 0.5 My), but little further change in half-dozen or so deep crustal sites to ∼ 160 Ma. High paleointensity that characterizes the last few thousand years may contribute significantly to the high on-axis magnetization. The task of evaluating changes in remanence of the extrusive layer is made more difficult by substantial cooling-rate-dependent changes in magnetic properties and the systematic variation in remanence with iron content (magnetic telechemistry). The commonly cited magnetic anomaly amplitude envelope is in fact not systematically observed – the Central Anomaly is elevated at slow-spreading ridges but is not as prominent at faster spreading rates. Nonetheless, magnetic anomaly amplitudes are consistent with magnetization change is poorly constrained. Direct determinations of the degree of low-temperature oxidation reveal the presence of highly oxidized titanomagnetite in samples less than 1 My old, suggesting a short (∼ 105 years) time constant though the effects of low-temperature oxidation are quite heterogeneous. While low-temperature oxidation does have some affect on lava magnetization and anomaly amplitudes, there is increasing evidence that marine magnetic anomalies are capable of recording a broad spectrum of geomagnetic field behavior, ranging from millennial-scale paleointensity variations to polarity reversals to apparent polar wander to, more speculatively, long-term changes in average field strength. Several emerging tools and approaches – autonomous vehicles, oriented samples, absolute paleointensity of near-ridge lavas, and measurements of the vector anomalous field – are therefore likely to significantly advance our understanding of the geomagnetic signal recorded in the oceanic crust, as well as our ability to utilize this information in addressing outstanding problems in crustal accretion processes

Understanding of the style of extension and the architecture of oceanic crust ― Drilling through the upper oceanic crust off-Hawaii

International Conference on Ophiolites and the Oceanic Lithosphereによる発表資料金沢大学理工研究域地球社会基盤学系conference pape

Investigating the Potential of Ridesharing to Reduce Vehicle Emissions

As urban populations grow, cities need new strategies to maintain a good standard of living while enhancing services and infrastructure development. A key area for improving city operations and spatial layout is the transportation of people and goods. While conventional transportation systems (i.e., fossil fuel based) are struggling to serve mobility needs for growing populations, they also represent serious environmental threats. Alternative-fuel vehicles can reduce emissions that contribute to local air pollution and greenhouse gases as mobility needs grow. However, even if alternative-powered vehicles were widely employed, road congestion would still increase. This paper investigates ridesharing as a mobility option to reduce emissions (carbon, particulates and ozone) while accommodating growing transportation needs and reducing overall congestion. The potential of ridesharing to reduce carbon emissions from personal vehicles in Changsha, China, is examined by reviewing mobility patterns of approximately 8,900 privately-owned vehicles over two months. Big data analytics identify ridesharing potential among these drivers by grouping vehicles by their trajectory similarity. The approach includes five steps: data preprocessing, trip recognition, feature vector creation, similarity measurement and clustering. Potential reductions in vehicle emissions through ridesharing among a specific group of drivers are calculated and discussed. While the quantitative results of this analysis are specific to the population of Changsha, they provide useful insights for the potential of ridesharing to reduce vehicle emissions and the congestion expected to grow with mobility needs. Within the study area, ridesharing has the potential to reduce total kilometers driven by about 24% assuming a maximum distance between trips less than 10 kilometers, and schedule time less than 60 minutes. For a more conservative maximum trip distance of 2 kilometers and passenger schedule time of less than 40 minutes, the reductions in traveled kilometers could translate to the equivalent of approximately 4.0 tons CO2 emission reductions daily