Month: June 2024

Aeromagnetic and field data characterization of structural features for the delineation of potential gold mining sites in Northern Cameroon: a case study of Tchollire and environs

Latest Results

Abstract

The processing of aeromagnetic data was carried out in Northern Cameroon, with the aim of delineating the structural features which may be associated with the gold occurrence. Hence, the Horizontal Gradient upward continued at 1, 3, 5, and 9 km, and Euler Deconvolution (using a structural index = 0), were applied in this study. As a result, contacts/faults were delineated from both methods. The solution depths of those contacts/faults were computed around 0.1–2.49 km from the Euler Deconvolution, with a good match with the contacts/faults obtained from the Horizontal Gradient upward continued at 1 km; the interpretation of the depth to the top and to the bottom of the Tchollire Banyo Shear Zone (TBSZ) was estimated between 0.1 and 0.49 km and > 4.5 km, respectively. Besides, the qualitative interpretation of the aeromagnetic data shows that the study area is characterized by contacts/faults trending in the NE–SW/ENE–WSW, E–W, and NW/SE–WNW–ESE directions which are consistent with the main structural directions observed in the field. Hence, the new structural framework was established from the aeromagnetic data processing results constrained with field data of Tchollire locality and environs; the structural deformation phases are defined by WNW–ESE to NW–SE foliation/schistosity linked to deformation phase D1, NE–SW/ENE–WSW regional foliation (D2), and E–W shear zones/contacts (D3). Furthermore, a proximal match was observed between both aeromagnetic lineaments and gold mining locations, suggesting a structural control of hydrothermal fluids linked to the gold mineralizations. Thus, the results of this study (lineaments and their depths) could serve as an important tool for prospective mining studies in Northern Cameroon.

Seasonal analysis of long-term (1970–2020) rainfall variability using clustering and wavelet transform approach in the Mahi River Basin, India

Latest Results

Abstract

Understanding the trend of seasonal rainfall in the context of climate change is crucial for the maintenance of regional water resources management. The present study examines the seasonal rainfall trend in the Mahi River basin, India by using the wavelet transform and clustering method. Daily gridded rainfall data (0.25° × 0.25° spatial resolution) for 51 grids from 1970 to 2020 have been taken from India Meteorological Department (IMD). The monthly, seasonal, and annual statistic has been analyzed for 51 years. We have also plotted the relationship between precipitation trend–elevation. After that, homogeneous precipitation regions are delineated with hierarchical clustering analysis. Results reveal that seasonal precipitation over the basin clusters into 4 subregions for monsoon and 3 subregions for winter, pre-monsoon, and post-monsoon seasons. After the regionalization of the subregions, the periodicity and the inter-seasonal relationship were analyzed using continuous wavelet transform (CWT). In addition, it was clear that the cross-correlation between pre-monsoon and monsoon seasons had a significant periodic change in the last 30 years over the basin. The basin is located adjacent to the Arabian sea, which makes the basin more sensitive to a natural event like ENSO, it can cause changes in ocean temperatures and atmospheric circulation patterns that affect precipitation patterns during the study period. It is expected that some natural phenomena like monsoon variability, low-level jet streams, and many more also have an impact on the rainfall patterns of the basin. Thus, the understanding of seasonal precipitation variation provides a practical reference for water resources management, agricultural planning, and a forecast of precipitation in different regions and river basins of India which may give a better climate change indication.

Intellectual property rights, taxation, and firms’ innovation: theory and evidence from China

Latest Results

Abstract

This study develops an R &D-based growth model with corporate taxation to explore the heterogeneous effects of intellectual property rights (IPR) protection on innovation of firms with different tax rates. Our theoretical analysis shows that strengthening IPR stimulates innovation, and a higher tax rate dampens the positive effect of IPR. To account for the interactive effect between IPR and taxation, we find supportive evidence for the theoretical result using firm-level data in China. Moreover, our empirical analysis shows that strengthening IPR is associated with less innovation by high-tax firms and more innovation by low-tax firms.

Revisiting conservation units for the endangered mountain yellow-legged frog species complex (Rana muscosa, Rana sierrae) using multiple genomic methods

Latest Results

Abstract

Insights from conservation genomics have dramatically improved recovery plans for numerous endangered species. However, most taxa have yet to benefit from the full application of genomic technologies. The mountain yellow-legged frog species complex, Rana muscosa and Rana sierrae, inhabits the Sierra Nevada mountains and Transverse/Peninsular Ranges of California and Nevada. Both species have declined precipitously throughout their historical distributions. Conservation management plans outline extensive ongoing recovery efforts but are still based on the genetic structure determined primarily using a single mitochondrial sequence. Our study used two different sequencing strategies – amplicon sequencing and exome capture – to refine our understanding of the population genetics of these imperiled amphibians. We used buccal swabs, museum tissue samples, and archived skin swabs to genotype frog populations across their range. Using the amplicon sequencing and exome capture datasets separately and combined, we document five major genetic clusters. Notably, we found evidence supporting previous species boundaries within Kings Canyon National Park with some exceptions at individual sites. Though we see evidence of genetic clustering, especially in the R. muscosa clade, we also found evidence of some admixture across cluster boundaries in the R. sierrae clade, suggesting a stepping-stone model of population structure. We also find that the southern R. muscosa cluster had large runs of homozygosity and the lowest overall heterozygosity of any of the clusters, consistent with previous reports of marked declines in this area. Overall, our results clarify management unit designations across the range of an endangered species and highlight the importance of sampling the entire range of a species, even when collecting genome-scale data.

The Hakcheon-Chogok Megaturbidite in the Miocene Pohang-Youngduk Basin, SE Korea: high-gradient slope failure probably triggered by a giant tsunami wave

Latest Results

Abstract

In ancient records, discrimination of specific triggering events from sediment gravity flow deposits is very difficult, due to multiple interactions between triggering events and similar sedimentary characteristics. For this study, we introduce the Hakcheon-Chogok Megaturbidite (HCM) in the Miocene Pohang-Youngduk Basin (PYB), providing an opportunity to differentiate the triggering events. This megaturbidite is over 70 m thick in the proximal part and less than 4 m thick in the distal part. The diachronous stratigraphic position and distinct coarser sediments than those of the underlying and overlying successions suggest a large-scale slope failure of the fine-grained foreset (more than 2 km3). The occurrence of exotic granitic boulders, originating from the basement rock, more than 1 km west of the present fan-apex, is indicative of extreme sea-level run-up. The dispersal pattern and paleocurrent direction suggest that the HCM flowed to the northeast, irrespective of the local depositional slope which show a radial distribution from the fan-apex. The distribution pattern almost perpendicular to the strike of the NW-SE trending transfer fault suggests that the HCM was triggered by a reflection flow of giant tsunami wave, resulting in a large-scale failure of high-gradient (> 15° in slope angle) fandelta slope.

Geochemistry of Stream Waters of the Lo River Catchment, Ha Giang Province (Northern Vietnam)

Latest Results

Abstract

A set of 41 stream water samples of the Lo River catchment, Ha Giang province, collected in dry season was analyzed for pH, major cation and anion, trace element concentrations. The stream waters exhibits a midly acidic to alkaline, meanwhile, the Total Dissolved Solids (TDS) values have a wide range of 17.4–284.9 mg L–1. Among major cations and anions, the stream water within the Lo River catchment is characterized by the predominant presence of Ca2+ and \({\text{HCO}}_{3}^{ - }\) . This compositional pattern gives rise to the emergence of the Ca–Mg–HCO3 water type as the most dominant species, followed by Na–Cl, Ca–Mg–Cl–SO4 and Na–HCO3–Cl types. However, the distribution of these water types corresponds closely with the geological conditions, with Na–Cl type prevailing in the watershed of granite complex, while watersheds characterized by lithologies such as Quaternary sediments, limestone, marble, shale, schist, and sandstone primarily exhibit the Ca–Mg–HCO3 water type. The dominant reaction in the water system is the dissolution of carbonate minerals, like calcite and dolomite, followed by the contribution of modest rainfall during the dry season, and small-scale processes of mixing and cation exchange. Comparison of major ions and trace element with technical standard reveal the stream waters are generally deemed suitable for the routine activities of the local population in Ha Giang province. However, stream water of a few specific sites may require treatment before these waters can be safely utilized.

Integration of satellite SAR and optical acquisitions for the characterization of the Lake Sarez landslides in Tajikistan

Latest Results

Abstract

Tajikistan is an area characterized by several lakes created after rockfalls and moraine deposits collapsed due to its geographic position on the collisional area of the Euro-Asian and Indian tectonic plates. In 1911, a violent earthquake generated the Usoi dam, which led to the creation of Lake Sarez. The purpose of the article is to provide an overview of the ground deformation of the two landslides that affect and threaten the area of Lake Sarez exploiting the combination of two different techniques, the interferometric synthetic aperture radar (InSAR) method with the SqueeSAR approach and optical image analysis through the use of COSI-Corr software. The combination of these two techniques turned out to be useful and provide more information because InSAR method balances lack the optical analysis and vice versa giving the possibility to obtain a complete overview of the displacement of the area. Moreover, InSAR data have been used to reconstruct the geometry and depth of the sliding surface of a potential landslide that could affect the lake, generating a wave that could overtop the dam and affect the villages downstream.

Radicalizing Theory and Vygotsky: Addressing Crisis Through Activist-Transformative Methodology

Latest Results

Abstract

In this paper, I discuss the topic of crisis and, more centrally, focus on methodologies to address it. My argument is that the methodology most useful to moving forward with research (including theorizing), especially at this time of crisis, is to clearly connect this work to, and embed it within, the ongoing sociopolitical struggles on the ground via contributing to, and taking a stance on, these struggles. This includes going to the roots of conflicts these struggles address, as the term radical implies. Arguably, this is the path to turning research into a critical/radical—and thus, also and simultaneously, theoretical/practical—work directly relevant to real-life issues and concerns. This is especially pertinent during the times of crisis since such times demand not only having a critical lens in order to interrogate the status quo but also, and more to the point, being decisive (as the word “crisis” implies), that is, ready and resolute to take a stand, stake a claim, and make a commitment to a particular future. I draw on Vygotsky’s methodology (grounded in Marxism) and expand it in several ways, including through the notion of ethico-ontoepistemology, to advance an activist-transformative methodology. In developing it, I draw on the scholarship of resistance by scholars of color and others who pursue activist agendas and connect to struggles on the ground. To preface this approach, I contrast it with what I term scholastic approaches to historical legacies.

Discussing the Concept of Crisis in Cultural-historical Activity Research: a Dialectical Perspective

Latest Results

Abstract

The concept of crisis has a long history across disciplines (medicine, history, political economy, political science, sociology, psychology, history, philosophy of science, etc.). This concept has been used in a variety of different ways. Vygotsky employed the concept of crisis in a critique of psychology as a ‘problematic discipline’. Additionally, Vygotsky used the concept of crisis to refer to the specific mechanisms related to psychological development. More generally, the concept of crisis is crucial for the conceptualisation of the process of development of Vygotsky’s project. From a dialectical perspective, a crisis is a critical moment of a dynamic, contradictory, developmental process. The elaboration of the concept of crisis as a part of a broader, dialectical vision of society in the long-term process of its historical development can become a moment of regenerating cultural-historical activity research.

How Community School Members Discuss Power: A Case Study

Latest Results

Abstract

School communities have been shut out of many of the more critical decision-making processes impacting local public schools. Decisions are mostly made as top-down actions from federal mandates, general assemblies, state departments, districts, and school level administration teams, isolating the school communities they are tasked to serve. To better understand the ways members of the school community can engage in decision making power, a critical discourse analysis was used to examine how school community members talk about power, who has power, and shifts in power as their schools undergo a community school implementation process. Using an updated public school model that is technically over a century old, some schools are using their communities to shift power through a community school model. Interviews and elicitation devices revealed that some school community members were beginning to understand their power through decision making. To continue this momentum, I recommend that community schools continue the discourse, make better distinctions between students and their data, and create parent liaison positions. In addition, community schools should look at ways to better engage parents, bus drivers, cafeteria workers, instructional assistants, and other classified staff to draw upon their expertise and knowledge. Finally, I urge districts and governance groups to consider the sustainability of their community schools and the actions they can take to ensure these schools have the time, funding, and power to make lasting, measurable changes.