Late 1980s Research Articles

Ricardo’s Law of Comparative Advantage in Bronze Age, Iron Age, and Early Historic Mainland Southeast Asian Metallurgy: Copper-base Metal Production, Exchange, and Consumption Behaviours at Khao Sai On, Nil Kham Haeng, Non Pa Wai, Phromthin Tai, Sab Champa, and Tha Kae in Central Thailand

Since its late 1970s to early 1980s discovery, the Khao Wong Prachan Valley (KWPV) of central Thailand has been assumed to have been a major supplier of copper in Bronze Age, Iron Age, and Early Historic Southeast Asia. KWPV was the first regional metal production system to be characterised by lead isotope (LI) analysis in the late 2000s, revealing a coherent signature easily distinguished from subsequent analyses of production systems at Phu Lon (northern Thailand) and the Vilabouly Complex (central Laos). Despite KWPV’s scale of production, its LI signature has scarcely been detected at Bronze Age metal consumption sites in nearby northeast Thailand and not at all in Iron Age assemblages. We study copper production and copper/bronze consumption behaviours of Iron Age and Early Historic sites in KWPV’s immediate vicinity: Khao Sai On, Phromthin Tai, Tha Kae, and Sab Champa. Khao Sai On and Phromthin Tai production signatures are highly consistent with those previously established, while the uranogenic tendency at Tha Kae explains outliers from Bronze Age Non Pa Wai and Nil Kham Haeng. Analysis of consumption assemblages reveals little to no consistency with local production signatures. This tendency was tested with LI Iron Age and Early Historic datasets for Ban Khu Muang, Ban Mai Chaimongkol, Ban Pong Manao, and Ban Pong Takhob. The pattern is clear: central Thai populations imported copper/bronze, potentially from the Vilabouly Complex or production loci with closely comparable signatures. We examine this counterintuitive behaviour inductively using Ricardo’s Law of Comparative Advantage combined with a technological appreciation of the relatively low productivity of central Thai primary copper production. This suggests central Thailand’s unattached copper producers freely exchanged copper for exotic goods (bronze, glass, semi-precious stone), with potentially poor terms of exchange, from their desire to participate in wider regional trends in conspicuous consumption.

Ricardo’s Law of Comparative Advantage in Bronze Age, Iron Age, and Early Historic Mainland Southeast Asian Metallurgy: Copper-base Metal Production, Exchange, and Consumption Behaviours at Khao Sai On, Nil Kham Haeng, Non Pa Wai, Phromthin Tai, Sab Champa, and Tha Kae in Central Thailand

Since its late 1970s to early 1980s discovery, the Khao Wong Prachan Valley (KWPV) of central Thailand has been assumed to have been a major supplier of copper in Bronze Age, Iron Age, and Early Historic Southeast Asia. KWPV was the first regional metal production system to be characterised by lead isotope (LI) analysis in the late 2000s, revealing a coherent signature easily distinguished from subsequent analyses of production systems at Phu Lon (northern Thailand) and the Vilabouly Complex (central Laos). Despite KWPV’s scale of production, its LI signature has scarcely been detected at Bronze Age metal consumption sites in nearby northeast Thailand and not at all in Iron Age assemblages. We study copper production and copper/bronze consumption behaviours of Iron Age and Early Historic sites in KWPV’s immediate vicinity: Khao Sai On, Phromthin Tai, Tha Kae, and Sab Champa. Khao Sai On and Phromthin Tai production signatures are highly consistent with those previously established, while the uranogenic tendency at Tha Kae explains outliers from Bronze Age Non Pa Wai and Nil Kham Haeng. Analysis of consumption assemblages reveals little to no consistency with local production signatures. This tendency was tested with LI Iron Age and Early Historic datasets for Ban Khu Muang, Ban Mai Chaimongkol, Ban Pong Manao, and Ban Pong Takhob. The pattern is clear: central Thai populations imported copper/bronze, potentially from the Vilabouly Complex or production loci with closely comparable signatures. We examine this counterintuitive behaviour inductively using Ricardo’s Law of Comparative Advantage combined with a technological appreciation of the relatively low productivity of central Thai primary copper production. This suggests central Thailand’s unattached copper producers freely exchanged copper for exotic goods (bronze, glass, semi-precious stone), with potentially poor terms of exchange, from their desire to participate in wider regional trends in conspicuous consumption.

Intersectionality, gender norms, and young adolescents in context: a review of longitudinal multicountry research programmes to shape future action.

Discriminatory gender norms can intersect and interact with other dimensions of discrimination-such as age, race, ethnicity, disability, education status, and sexual orientation-to shape individuals' experiences and impact their health and wellbeing. This interaction is referred to as intersectionality. Although the theory has been in circulation since the late 1980s, only recently has it gained traction in low-income and middle-income settings, and it has yet to fully penetrate global research on adolescence. The social and structural intersectional drivers of adolescent health and wellbeing, particularly during early adolescence (age 10-14 years), are poorly understood. The evidence base for designing effective interventions for this formative period of life is therefore relatively small. In this Review, we examine how gender intersects with other forms of disadvantage in the early stages of adolescence. Analysing data from hybrid observation-intervention longitudinal studies with young adolescents in 16 countries, our aim is to inform the health and wellbeing of girls and boys from a range of social contexts, including in conflict settings. Adolescents' perceptions about gender norms vary by context, depend on individual opinion, and are shaped by socioecological drivers of gender inequalities in health. Shifting those perceptions is therefore challenging. We argue for the importance of applying an intersectionality lens to improve health and wellbeing outcomes for young adolescents and conclude with five practical recommendations for programme design and research.

Communalism Factor in Evolution of Political Situation in British India (1920s-1930s)

This article delves into specific aspects of complex political processes that unfolded in the interwar decades in British India, serving as the foundation for the subsequent decolonization of Hindustan. Drawing from an analysis of documentary sources and literary works, a comprehensive overview is provided regarding the factors shaping Indian communalism and the conceptual perspectives of its proponents during the period under review. The study concludes on the contradictory nature of colonial policy during this period. On one hand, it contributed to the formation of elements of political culture within Indian society and to some extent laid the groundwork for India’s future federative system. On the other hand, its aim was to deepen divisions among various ethno-confessional and social groups of the Indian population to solidify control over a key segment of the British colonial system. The actions of colonial authorities significantly exacerbated relations between key ethno-confessional groups of the Indian population by the late 1930s, setting the stage for the dramatic post-World War II processes leading to the partition of British India into two sovereign entities. The complex relations between these entities largely shape the contemporary character of international relations in South Asia.

Exploration of the value of Japanese-style gardens in incarceration camps during world war II: the case of the Amache, Colorado, U.S.

ABSTRACT Japanese immigration to the U.S. began in the late 1800s. Japanese immigrants and later their children were mostly engaged in agriculture; however, some owned nurseries and gardening or landscaping businesses. Following the outbreak of World War II, most Japanese and Japanese Americans were sent to one of ten incarceration camps, one of which was Amache, in the High Plains of Colorado. Inmates there planted trees and created hundreds of gardens to improve its stark institutional landscape. These gardens were located in the front of individual barracks and other public spaces. They formed the most significant landscape element within the camp and helped Japanese inmates retain their identities during wartime. This study focuses on two Japanese-style gardens created in the public spaces of barracks Blocks 6H and 12F in the Amache incarceration camp. Framed by archival research on professional gardener associations and the Japanese language section of the camp newspaper, it explores the significance of these Japanese-style gardens, revealing the value and role the gardens played among Japanese detainees. It also reveals the long-term impact of these gardens as a material legacy.

Effects of silvicultural release on artificial oak regeneration in bottomland hardwood forests in northern Missouri

In bottomland forests, managing oak regeneration is challenging due to competition with other species. Low understory light levels in mature stands favor more shade-tolerant tree species, whereas harvest often results in release of fast-growing competitors. In the late 1990s, a study was initiated in northeastern Missouri to evaluate the effects of overstory harvests on stand development of bottomland forests, with particular interest in oak regeneration. Canopy removal resulted in rapid growth of undesired soft-mast species without increasing the abundance of oak reproduction. In 2017, bare-rooted pin oak (Quercus palustris Muenchh.) and swamp white oak (Quercus bicolor Willd.) seedlings were planted, to increase the oak component through enrichment planting in the stands that had previously been harvested and underplanting in the stands that had received no regeneration harvest. For all planted seedlings, three levels of midstory release treatments were applied after planting in 2017, including a control (no release), and light release, and a heavy release. This study tested the effects of the original overstory harvests and the subsequent midstory release on survival and development of planted oak advance reproduction over 5 years. Our results suggest that establishing oak advance reproduction prior to overstory harvest is more efficient than enrichment planting after overstory harvest. A prior midstory release is important to develop competitive oak advance reproduction before a later overstory harvest to ensure successful oak regeneration.

Quality vs. Quantity: the Consequences of Elevated CO2 on Wood Biomaterial Properties.

Since the late 1800s, anthropogenic activities such as fossil fuel consumption and deforestation have driven up the concentration of atmospheric CO2 around the globe by more than 45%. Such heightened concentrations of carbon dioxide in the atmosphere are a leading contributor to global climate change with estimates of a 2-5 degree increase in global air temperature by the end of the century. While such climatic changes are mostly considered detrimental, a great deal of experimental work has shown that increased atmospheric CO2 will actually increase growth in various plants, which may lead to increased biomass for potential harvesting or CO2 sequestration. However, it is not clear whether this increase in growth or biomass will be beneficial to the plants, as such increases may lead to weaker plant materials. In this review, I examine our current understanding of how elevated atmospheric CO2 caused by anthropogenic effects may influence plant material properties focusing on potential effects on wood. For the first part of the review, I explore how aspects of wood anatomy and structure influence resistance to bending and breakage. This information is then used to review how changes in CO2 levels may later these aspects of wood anatomy and structure in ways that have mechanical consequences. The major pattern that emerges is that the consequences of elevated CO2 on wood properties is highly dependent on species, and environment, with different tree species showing contradictory responses to atmospheric changes. In the end, I describe a couple avenues for future research into better understanding the influence of atmospheric CO2 levels on plant biomaterial mechanics.

Association of Childhood Exposure to School Racial Segregation with Late-Life Cognitive Outcomes among Older Americans.

Disparities in cognition, including dementia occurrence, persist between White and Black older adults, and are possibly influenced by early educational differences stemming from structural racism. However, the relationship between school racial segregation and later-life cognition remains underexplored. To investigate the association between childhood contextual exposure to school racial segregation and cognitive outcomes in later life. Data from 16,625 non-Hispanic White (hereafter, White) and 3,335 non-Hispanic Black (hereafter, Black) Americans aged 65 or older were analyzed from the Health and Retirement Study. State-level White-Black dissimilarity index for public elementary schools in the late 1960s (range: 0-100) was used to measure school segregation. States were categorized into high segregation (383.6) and low segregation (<83.6) based on the top quintile. Cognitive scores, cognitive impairment (with or without dementia), and dementia were assessed using the Telephone Interview for Cognitive Status (TICS) and proxy assessment. Multilevel regression analyses were conducted, adjusting for demographic covariates, socioeconomic status, and health factors. Stratified analyses by race were performed. The mean (SD) age of participants was 78.5 (5.7) years, and 11,208 (56.2%) were female. Participants exposed to high segregation exhibited lower cognitive scores (12.6 vs. 13.6; P<0.001) and higher prevalence of cognitive impairment (50.8% vs 41.4%; P<0.001) and dementia (26.0% vs. 19.5%; P<0.001), compared to those with low segregation exposure. Multilevel analyses revealed a significant negative association between school segregation and later-life cognitive even after adjusting sequentially for potential confounders, and these associations were stronger among Black than White participants. Notably, in the fully adjusted model, Black participants exposed to high segregation displayed significantly lower cognitive scores (-0.51; 95% CI: -0.94, -0.09) and higher likelihood of cognitive impairment (adjusted Odds Ratio [aOR]: 1.45, 95% CI: 1.22, 1.72) and dementia (aOR: 1.31, 95% CI: 1.06, 1.63). Our study underscores that childhood exposure to state-level school segregation is associated with late-life cognition, especially for Black Americans. Given the rising trend of school segregation in the US, educational policies aimed at reducing segregation are crucial to address health inequities. Clinicians can leverage patients' early-life educational circumstances to promote screening, prevention, and management of cognitive disorders.

Right to Development and the Role of DAC OECD Foreign Aid to Development in Africa

When the concept of the human right to development was articulated in Africa in the late 1960s and early 1970s, the idea was not to ask for development aid but to assert the right to self-determination, or even the right to genuine liberation from continued external domination, in order to assume sovereign control and determine the continent’s own developmental destiny. However, in the course of evolution, the idea of the right to development has been distorted to some extent and has been thwarted in order to imply recourse for its realization. Developed countries were required to provide 0.7% of their annual gross domestic product as foreign aid to assist developing countries, including African countries, in their efforts to achieve comprehensive development. Over more than six decades, from 1960 to 2022, the Development Assistance Committee of the Organization for Economic Cooperation and Development (DAC OECD) donor countries provided a total of USD 1.23 trillion in development assistance to 48 recipient countries in Africa. This paper examines the extent to which the foreign aid allocations have contributed to development of recipient countries in Africa. The findings illustrate that despite the continued shipment of foreign aid to Africa, impoverishment and underdevelopment have worsened across the continent, raising the question of why Africa should remain trapped in the DAC OECD “dead aid” conundrum when alternative, mutually beneficial development cooperation mechanisms could be explored.

A dynamic microRNA profile that tracks a chemotherapy resistance phenotype in osteosarcoma. Implications for novel therapeutics.

Osteosarcoma is a rare primary bone tumor for which no significant therapeutic advancement has been made since the late 1980s despite ongoing efforts. Overall, the five-year survival rate remains about 65%, and is much lower in patients with tumors unresponsive to methotrexate, doxorubicin, and cisplatin therapy. Genetic studies have not revealed actionable drug targets, but our group, and others, have reported that epigenomic biomarkers, including regulatory RNAs, may be useful prognostic tools for osteosarcoma. We tested if microRNA (miRNA) transcriptional patterns mark the transition from a chemotherapy sensitive to resistant tumor phenotype. Small RNA sequencing was performed using 14 patient matched pre-chemotherapy biopsy and post-chemotherapy resection high-grade osteosarcoma frozen tumor samples. Independently, small RNA sequencing was performed using 14 patient matched biopsy and resection samples from untreated tumors. Separately, miRNA specific Illumina DASL arrays were used to assay an independent cohort of 65 pre-chemotherapy biopsy and 26 patient matched post-chemotherapy resection formalin fixed paraffin embedded (FFPE) tumor samples. mRNA specific Illumina DASL arrays were used to profile 37 pre-chemotherapy biopsy and five post-chemotherapy resection FFPE samples, all of which were also used for Illumina DASL miRNA profiling. The National Cancer Institute Therapeutically Applicable Research to Generate Effective Treatments dataset, including PCR based miRNA profiling and RNA-seq data for 86 and 93 pre-chemotherapy tumor samples, respectively, was also used. Paired differential expression testing revealed a profile of 17 miRNAs with significantly different transcriptional levels following chemotherapy. Genes targeted by the miRNAs were differentially expressed following chemotherapy, suggesting the miRNAs may regulate transcriptional networks. Finally, an in vitro pharmacogenomic screen using miRNAs and their target transcripts predicted response to a set of candidate small molecule therapeutics which potentially reverse the chemotherapy resistance phenotype and synergize with chemotherapy in otherwise treatment resistant tumors. Importantly, these novel therapeutic targets are distinct from targets identified by a similar pharmacogenomic analysis of previously published prognostic miRNA profiles from pre chemotherapy biopsy specimens.

Right to Development and the Role of DAC OECD Foreign Aid to Development in Africa

When the concept of the human right to development was articulated in Africa in the late 1960s and early 1970s, the idea was not to ask for development aid but to assert the right to self-determination, or even the right to genuine liberation from continued external domination, in order to assume sovereign control and determine the continent’s own developmental destiny. However, in the course of evolution, the idea of the right to development has been distorted to some extent and has been thwarted in order to imply recourse for its realization. Developed countries were required to provide 0.7% of their annual gross domestic product as foreign aid to assist developing countries, including African countries, in their efforts to achieve comprehensive development. Over more than six decades, from 1960 to 2022, the Development Assistance Committee of the Organization for Economic Cooperation and Development (DAC OECD) donor countries provided a total of USD 1.23 trillion in development assistance to 48 recipient countries in Africa. This paper examines the extent to which the foreign aid allocations have contributed to development of recipient countries in Africa. The findings illustrate that despite the continued shipment of foreign aid to Africa, impoverishment and underdevelopment have worsened across the continent, raising the question of why Africa should remain trapped in the DAC OECD “dead aid” conundrum when alternative, mutually beneficial development cooperation mechanisms could be explored.

Like mama always said: family socio-economic status, maternal attitudes and leader role occupancy in adulthood

Leadership research has always recognised the importance of childhood factors for the occupation of formal or informal leader positions later in life. Still, empirical research in the field has mainly been based on retrospective accounts from selective and small samples. Such research has also concentrated on individual traits and experiences, less on characteristics of the family. Our aim is to fill this void by prospectively examining the role of the family of origin on educational attainment and holding a managerial position in adulthood. Analyses were based on the Stockholm Multigenerational Study, including register and survey data, regarding 3,088 males born between 1950 and 1976 and their mothers’ attitudes to education and child-rearing in the late 1960s. Our results showed a significant effect of family socio-economic status (SES) on managerial role occupancy in late adulthood. This effect was mainly mediated through educational level. However, a noteworthy share of the total effect of family SES was channelled through maternal attitudes towards education. Positive attitudes towards education in the home environment accounted for an equally large share of the total indirect effect of family SES as the offspring’s cognitive capacity did. Authoritarian attitudes to child-rearing among mothers were also found to have a negative impact on cognitive capacity and educational level – two well-known antecedents to leader emergence. Parental attitudes may boost or modify structural characteristics and individual traits associated with holding formal leader roles such as a managerial position – but also showed an independent effect several decades later.

Российско-американские отношения конца XX – первой четверти XXI века: тенденции и перспективы

The article studies the relations between Russia and the USA in the late 20th – first decades of the 21st centuries as a central problem of modern international relations. The analysis is performed in the historicalpolitical retrospect, from the 1990s to the present day. When it comes to the 1990s, viewed as a time of friendship and partnership, the reasons for the rapprochement between the two countries are described, as well as the events of the late 1990s – eastward NATO expansion and the NATO bombing of Belgrade – which were the turning point for the decline in Russia–US relations. Talking about the 2000s – 2010s, the author indicates the contradictions in the development of the bilateral relations, namely, a trend towards both improvement (establishment of the NATO–Russia Council following the attacks of September 11, 2001 and the “reset” policy in the late 2000s) and deterioration (as a result of the US-led invasion of Iraq in 2003, Russo-Georgian conflict in August 2008, Syrian civil war, Ukrainian political crisis and the accession of Crimea to Russia in 2014). According to the author, Russian-American relations over the past decade (2014–2024) could be described as hostile, which eliminates the possibility for their normalization through direct contacts between the two parties. The downward trend in Russia– US relations, which emerged in the late 1990s and continued to grow during the 2000s – 2020s, can be explained by the two countries’ irreconcilable positions on the system of international relations. The United States seek to create a unipolar – Americentric – world, while Russia insists on multipolarity. According to the author, the only way to improve relations between Russia and the USA is to stabilize the system of international relations. This problem is discussed in the final part of the article.

How the other half works: Claudia Goldin's contributions to our understanding of women's labour market outcomes

AbstractThe Royal Swedish Academy of Sciences awarded the 2023 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel to Claudia Goldin “for having advanced our understanding of women's labour market outcomes”. This paper surveys Goldin's contributions, analysing women's labour force participation from the late 1700s through to the present. To document women's participation in the workforce, Goldin uncovered rich data from varied sources, from government reports and city directories to health surveys and university registration cards. She combined these data with economic theory to identify the factors affecting women's employment and to explore how we might achieve gender equity today. Her work has had an immense influence on how we understand the labour market, household decision‐making, and gender inequality.

Siberian Pine and Larch Response to Warming-Drying Climate in the Southern Boundary of Their Range

Trees’ growth and areal responses to changing climate are primarily expected within the edges of the species range. Here, we compared the responses of Siberian pine (Pinus sibirica Du Tour), a moisture-sensitive species, and drought-resistant larch (Larix sibirica Ledeb.) at the southern part of their ranges in the Siberian Mountains (the Tannu-Ola Ridge). We study the species’ growth and proportion in the forests from forest-steppe to treeline ecotone along the elevation gradient. These studies are based on radial growth index (GI) analysis and GI dependence on the climate variables. We used satellite time series to detect the land cover changes (areas of larch and Siberian pine, as well as shrubs and birch). We compared trees’ GI before and after warming “restart” in the late 1990s. Generally, GI dependence on the air temperature was negative at elevations below c. 1600 m a.s.l., whereas GI dependence on the moisture variables (precipitation, vapor pressure deficit, and soil moisture) was positive for both species. Above 1600 m, increasing air temperatures stimulated species growth, whereas the influence of moisture variables was negative (for larch) or neutral (for Siberian pine). After the warming restart, the GI of both conifers increased in moisture-sufficient high elevations and treeline ecotone, whereas within low elevations (&lt;1300 m), the GI was stagnant or suppressed. Both species’, especially Siberian pine, negative growth dependence on air temperature and positive dependence on the moisture variables strongly increased since the warming restart. We found a risen growth dependence of both species on the soil-stored water during the previous year (September–October), which smoothed moisture stress at the beginning of the growing season. Yet both species’ growth also suffered as a result of early spring warms. We found that larch is migrating in both uphill and downhill directions, while Siberian pine is migrating uphill only. Forests loss occurred at low elevations (&lt;1300 m), whereas forest and shrub gain occurred at high (&gt;2000 m) ones. The upper boundary of the forests and shrubs is migrating uphill at rates of about 0.8 and 0.3 m/y, respectively. We observed a decrease in Siberian pine proportion in the forests, whereas areas of larch and birch strongly increased (by 150% and 100%, respectively), which indicates the retreat of Siberian pine from its southern habitat. We suggested afforestation of the areas of Siberian pine mortality by the drought-tolerant larch species.

Novel Targets and Advanced Therapies in Diffuse Large B Cell Lymphomas.

Since the introduction of rituximab in the late 1990s, significant progress has been made in advancing targeted therapies for B cell lymphomas, improving patients' chance of being cured and clinicians' therapeutic armamentarium. A better understanding of disease biology and pathogenic pathways, coupled with refinements in immunophenotypic and molecular diagnostics, have been instrumental in these achievements. While traditional chemotherapy remains fundamental in most cases, concerns surrounding chemorefractoriness and cumulative toxicities, particularly the depletion of the hemopoietic reserve, underscore the imperative for personalized treatment approaches. Integrating targeted agents, notably monoclonal antibodies, alongside chemotherapy has yielded heightened response rates and prolonged survival. A notable paradigm shift is underway with innovative-targeted therapies replacing cytotoxic drugs, challenging conventional salvage strategies like stem cell transplantation. This review examines the landscape of emerging targets for lymphoma cells and explores innovative therapies for diffuse large B cell lymphoma (DLBCL). From Chimeric Antigen Receptor-T cells to more potent monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, checkpoint inhibitors, and small molecules targeting intracellular pathways, each modality offers promising avenues for therapeutic advancement. This review aims to furnish insights into their potential implications for the future of DLBCL treatment strategies.

Strengthened Combined Impact of the Pacific and Atlantic Meridional Modes on Eastern North Pacific Tropical Cyclones since the 1990s

Abstract There has been increased focus in recent years on the impact of the Pacific meridional mode (PMM) and the Atlantic meridional mode (AMM) on weather and climate events. This study shows an increased synergistic impact of both the PMM and AMM on eastern North Pacific (ENP) extended boreal summer (June–November) tropical cyclone frequency (TCF) since the 1990s. This increase in the combined impact of both the PMM and AMM on ENP TCF is mainly due to a stronger modulation of the AMM on TCF since the early 1990s and of a stronger modulation of the PMM on TCF since the late 1990s. A budget analysis of the genesis potential index highlights the important contribution of changes in vertical wind shear to the recent strengthened AMM–TCF relationship, while potential intensity and vertical wind shear are the two most important drivers of the recent increase in the PMM–TCF relationship. This intensified association is largely explained by changes in the mean state of sea surface temperatures in the tropical Atlantic associated with the Atlantic multidecadal oscillation (AMO) and trade wind magnitude in the subtropical Pacific Ocean associated with the Pacific decadal oscillation (PDO). This study highlights an asymmetric effect of the AMO and PDO on these two meridional modes and ENP TC genesis frequency and provides a better understanding of ENP TC activity on interannual-to-decadal time scales.

Laser-driven ion and electron acceleration from near-critical density gas targets: Towards high-repetition rate operation in the 1 PW, sub-100 fs laser interaction regime

Ion acceleration from gaseous targets driven by relativistic-intensity lasers was demonstrated as early as the late 1990s, yet most of the experiments conducted to date have involved picosecond-duration, Nd:glass lasers operating at low repetition rate. Here, we present measurements on the interaction of ultraintense (≈1020Wcm−2, 1 PW), ultrashort (≈70fs) Ti:Sa laser pulses with near-critical (≈1020cm−3) helium gas jets, a debris-free targetry with the potential for future compatibility with high (≈1 Hz) repetition rate operation. We provide evidence of α particles being forward accelerated up to ≈2.7−MeV energy with a total flux of ≈1011sr−1 as integrated over &gt;0.1−MeV energies and detected within a 0.5−mrad solid angle. We also report on on-axis emission of relativistic electrons with an exponentially decaying spectrum characterized by a ≈10−MeV slope, i.e., five times larger than the standard ponderomotive scaling. The total charge of these electrons with energy above 2 MeV is estimated to be of ≈1nC, corresponding to ≈0.1% of the laser drive energy. In addition, we observe the formation of a plasma channel, extending longitudinally across the gas density maximum and expanding radially with time. These results are well captured by large-scale particle-in-cell simulations, which reveal that the detected fast ions most likely originate from reflection off the rapidly expanding channel walls. The latter process is predicted to yield ion energies in the MeV range, which compare well with the measurements. Finally, direct laser acceleration is shown to be the dominant mechanism behind the observed electron energization. Published by the American Physical Society 2024

Comparative genomic analysis of Bradyrhizobium strains with natural variability in the efficiency of nitrogen fixation, competitiveness, and adaptation to stressful edaphoclimatic conditions.

Bradyrhizobium is known for fixing atmospheric nitrogen in symbiosis with agronomically important crops. This study focused on two groups of strains, each containing eight natural variants of the parental strains, Bradyrhizobium japonicum SEMIA 586 (=CNPSo 17) or Bradyrhizobium diazoefficiens SEMIA 566 (=CNPSo 10). CNPSo 17 and CNPSo 10 were used as commercial inoculants for soybean crops in Brazil at the beginning of the crop expansion in the southern region in the 1960s-1970s. Variants derived from these parental strains were obtained in the late 1980s through a strain selection program aimed at identifying elite strains adapted to a new cropping frontier in the central-western Cerrado region, with a higher capacity of biological nitrogen fixation (BNF) and competitiveness. Here, we aimed to detect genetic variations possibly related to BNF, competitiveness for nodule occupancy, and adaptation to the stressful conditions of the Brazilian Cerrado soils. High-quality genome assemblies were produced for all strains. The core genome phylogeny revealed that strains of each group are closely related, as confirmed by high average nucleotide identity values. However, variants accumulated divergences resulting from horizontal gene transfer, genomic rearrangements, and nucleotide polymorphisms. The B. japonicum group presented a larger pangenome and a higher number of nucleotide polymorphisms than the B. diazoefficiens group, possibly due to its longer adaptation time to the Cerrado soil. Interestingly, five strains of the B. japonicum group carry two plasmids. The genetic variability found in both groups is discussed considering the observed differences in their BNF capacity, competitiveness for nodule occupancy, and environmental adaptation.IMPORTANCEToday, Brazil is a global leader in the study and use of biological nitrogen fixation with soybean crops. As Brazilian soils are naturally void of soybean-compatible bradyrhizobia, strain selection programs were established, starting with foreign isolates. Selection searched for adaptation to the local edaphoclimatic conditions, higher efficiency of nitrogen fixation, and strong competitiveness for nodule occupancy. We analyzed the genomes of two parental strains of Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens and eight variant strains derived from each parental strain. We detected two plasmids in five strains and several genetic differences that might be related to adaptation to the stressful conditions of the soils of the Brazilian Cerrado biome. We also detected genetic variations in specific regions that may impact symbiotic nitrogen fixation. Our analysis contributes to new insights into the evolution of Bradyrhizobium, and some of the identified differences may be applied as genetic markers to assist strain selection programs.

‘Linguistic compatriots’: on the relationship between Tajik and Judeo-Tajik language and literature

ABSTRACT This paper follows the traces of Tajik and Judeo-Tajik literature in the early Soviet period and compares some prominent works and biographies of Tajik and Bukharan Jewish writers. In the 1920s and 1930s, national literatures were heavily supported by the Party and the state and used as vehicles for propagating the new ideology, creating Soviet nationalities (the Tajiks) and national minorities (the Bukharan Jews). For a period that lasted about ten years, parallels and mutual influences within an emerging scene of Tajik and Bukharan Jewish literature are well documented. While this laboratory of Soviet nation-building continued with the Tajiks, the Judeo-Tajik project was stopped in the late 1930s. From then until the end of the Soviet period, Bukharan Jewish writers, artists, and intellectuals contributed to mainstream Tajik culture.