bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of slugs for self-designed Ti-alloy shaped charge liner after penetrating reinforced concrete and steel target
Authors: Xue Xinying
Published: August 2024

Shaped charge liners were sintered from a self-designed β-Ti alloy by powder metallurgy. Although the lightweight β-Ti alloy shows the characteristics of a brittle material, the shaped charge liner forms a Ti-alloy jet, which is capable of penetrating 45# steel and C40 reinforced concrete under the detonation of an 8701 explosive. After penetration, the slugs are characterized by X-ray diffraction and optical micrography. Compared with α’ laths in the slug after penetrating the steel, those are found to be more sparse, shorter, and thicker in the slug after penetrating the C40 concrete, since the slug is extruded less severely. Moreover, the streamline is more remarkable in the slug after penetrating the C40 concrete. It is suggested that the α→β phase transformation occurred due to the adiabatic temperature rise during the penetration, followed by martensite transformation β→α’ due to rapid cooling.
Optimization of high-precision pyroelectric coefficient testing method
Authors: Zhang Hengda , Xiao Bo , Wang Xiaobo , Wu Delin , Gao Shenping , Wang Hongyuan , Jin Pian , Yu Xingyan , Yao Lei
Published: August 2024

In response to the existing GB/T 3389-2008 “Test Methods for Performance of Piezoelectric Ceramic Materials” (hereinafter referred to as GB/T 3389-2008), the charge integration method used for pyroelectric coefficient testing has the shortcomings that the charge quantity does not vary significantly with temperature, the process of the oil bath heating is nonlinear, the oil bath medium itself carrying charges causes errors in the test result, the capacitance of the integrating capacitor causes the mismatch in testing accuracy, and the testing range of the electrostatic meter is limited. Based on these situations, this paper proposes a more reliable high-precision pyroelectric coefficient testing method. This method adopts a more optimal step heating mode combined with small range temperature fluctuations to meet the high-sensitivity testing requirements. Electrode heating is used instead of oil bath heating to eliminate errors caused by the charges of the oil bath medium. Finally, a KEITHLEY model 6517B electrometer is employed to replace the electrostatic meter and the integrating capacitor, improving the testing accuracy while adapting to a larger measurement range.
Diamond wire saw forming cutting simulation analysis of arc workpieces
Authors: Fan Honghao
Published: August 2024

The application of diamond wire saws in the field of cutting hard and brittle materials is becoming increasingly widespread, especially in the photovoltaic industry where the demand for slicing processes for monocrystalline and polycrystalline silicon is continuously growing. Among these, the craftsmanship involved in arc-shaped workpieces is particularly complex. To analyze the impact of diamond wire saw processes on arc-shaped workpieces, PFC discrete element simulation software was utilized, aiming to produce a 1/8 arc segment, and the influence of the wire saw’s linear speed on the process was analyzed. The simulation results indicate that an increase in linear speed leads to improved particle distribution and a shape more closely resembling a circular form. However, the cutting process with a diamond wire saw must be controlled at an appropriate operating speed. If the speed is too high, it may lead to the destruction of the workpiece.
A design of Ultra Wideband (UWB) antenna applied in coal mine underground
Authors: Yang Yong
Published: August 2024

This article designs an ultra-wideband (UWB) hourglass-shaped antenna for underground coal mines, using FR-4 as the dielectric substrate, with microstrip feeder feeding, whose radiation direction can be changed using guides. On the basis of theoretical calculation, MATLAB high-frequency structure simulation software is used to simulate and analyze, and the final structure model and the optimal parameter value are determined according to the model construction and parameter sweep optimization. According to the simulation results, the relative bandwidth of the designed antenna is 109.3% (3.96 GHz~13.51 GHz), the return loss at the two resonant points is −30.99 dB and −28.22 dB, the standing wave ratio is 1.06 and 1.08, and the maximum gain is 6.2 dB. The designed antenna also has a simple structure, high economy, ultra wideband, high transmission efficiency, strong anti-interference performance, relatively small size, and a wide range of applications, which is conducive to design and development.
Effect of annealing treatment on electromagnetic parameters and wave-absorbing properties of Fe-based soft magnetic particles
Authors: Wang Wei , Wang Xiaodong
Published: August 2024

Fe-based soft magnetic particles have excellent soft magnetic properties but have limitations in practical applications. In order to obtain better wave-absorbing properties, Fe-based soft magnetic particles have been modified to meet the demand for their properties. The wave-absorbing properties of Fe-based soft magnetic amorphous powders are improved by annealing them, because annealing not only increases the dielectric constant and permeability of the material but also improves the soft magnetic properties of the material and increases the impedance matching of electromagnetic waves. Compared with the as-prepared state, although the annealing treatment cannot increase the peak value of the wave absorption peak, it can make the wave absorption frequency domain wider and the area of the wave absorption peak larger. The samples annealed at 500°C have excellent wave-absorbing properties in the 8-10 GHz and 14-18 GHz bands.
The analysis of aging characteristics of RTV insulating coatings with varying silicone rubber contents
Authors: Zhang Xinxin , Zhou Yuanxiang , Zhu Xiaoqian , Yu Jingzhe , Huang Xiaolong , Su Bin , Liu Min , Fan Shuochao
Published: August 2024

Room-temperature vulcanized silicone rubber coatings are widely used in the field of high-voltage outdoor insulation. Silicone rubber (RTV-SIR) coatings are used to improve the anti-pollution flashover performance of high-voltage ceramic insulators by imparting hydrophobicity to the surface. Different high-temperature aging experiments were conducted on coating samples with varying silicone rubber contents, and their physicochemical properties were tested to analyze the aging mechanisms involved, aiming to further evaluate the lifespan of the coatings. It was observed that lower silicone rubber content led to more significant changes in surface functional groups, accelerated degradation of coating properties during aging, and increased susceptibility to microcrack formation and subsequent crack development, further promoting the aging process. The aging process accelerated gradually from the surface to deeper layers at the same temperature, resulting in increased disorder and densification of the three-dimensional network structure, along with fragmentation of low-molecular-weight molecules.
An improved surface defect detection method based on DeepLabv3+ for piston pins
Authors: Cao Yifan , Zhang Jianwu , Xu Yunlong , Yu Bangqi , Li Hong
Published: August 2024

To address the pressing challenges of slow computation and suboptimal edge feature extraction in current piston pin surface defect detection techniques, this study introduces a refined methodology. By leveraging MobileNetV2, a streamlined convolutional backbone network, our approach accelerates processing speeds. Concurrently, the integration of an attention mechanism ensures that the model devotes increased focus to both edge irregularities and minute defect details. A tailored loss function mitigates the prevalent issue of sample imbalance, further enhancing model performance. Empirical evidence drawn from the piston pin dataset evidences the efficacy of our improvements: an MIoU of 85.41, MPA of 88.45, and a frame rate of 32.64 FPS, marking substantial gains in both accuracy and speed relative to pre-upgraded benchmarks. This optimized method not only delivers precise and timely defect delineation with a reduced parameter count, but it also contributes a novel and efficacious strategy for enhancing surface defect detection outcomes.
Comparison of AgCuSn15 brazing fillers prepared by mechanical alloying and layer composite methods for vacuum brazing of Ni substrate: microstructure and mechanical properties analysis
Authors: Song Ruili , Zhao Jiacun , Chen Jiacheng , Tian Caili
Published: August 2024

In order to reduce the brazing temperature of Ag-based filler and simultaneously avoid the problem of difficult processing, AgCuSn15 brazing fillers prepared by mechanical alloying method (named MA-1) and layer composite method (named LC-2) were employed to vacuum braze Ni substrate. The microstructure and mechanical properties of Ni/Ni joints brazed using MA-1 and LC-2 were compared. The effects of brazing temperature and brazing time on the mechanical properties of joints brazed using MA-1 were studied. The results suggest that the microstructure of the joint brazed using MA-1 is Ni/(Ni, Cu)3Sn + (Cu, Ni)6Sn5/Ag(s, s)+Cu(s, s)/(Cu, Ni)6Sn5+(Ni, Cu)3Sn/Ni, and there are small cracks caused by Cu6Sn5 phase in the joint. Due to the incomplete alloying of AgCu and Sn, the microstructure of joint brazed using LC-2 is Ni/(Cu, Ni)6Sn5+(Ni, Cu)3Sn/Ag(s, s)+Cu(s, s)+Ag-Cu eutectic/(Ni, Cu)3Sn +(Cu, Ni)6Sn5/Ni. The strength of the Ni/Ni joint brazed using MA-1 is highest (42.74 Mpa) at 680°C for 30 min. The strength of the Ni/Ni joint brazed using LC-2 under the same conditions is 24.86 Mpa.
Dynamic monitoring of spring strain and fatigue in high voltage circuit breakers
Authors: Cheng Yingzhe , Xu Zhixin , Weng Deming , Pan Qindi , Xie Peng , Chen Kuosong , Chen Sheng , Lin Jianlong , Chen Jiehao , Wang Weimin
Published: August 2024

The performance of high-voltage circuit breaker springs is crucial for the normal operation, safety performance, and equipment reliability of the circuit breaker. Their main functions include contact separation, rapid action, and load support. Therefore, it is required that the springs have good long-term stable performance and are not easily deformed or damaged. The circuit breaker spring may experience creep, fracture, and other conditions during use, resulting in abnormal working conditions of the circuit breaker and the inability to close. At present, the main maintenance methods adopt manual regular inspections and calibration of springs, which belong to post-control measures and cannot monitor the status of springs. This article studies the quantitative relationship between spring stress and strain, fatigue, and creep states, analyzes the changes in principal stress and shear stress during fatigue cracks, and monitors the status of springs by studying the optimal position of strain gauges.
Study on the effect of impeller wear on dredging pump performance under medium-coarse sand conditions
Authors: Zhao Guoquan , Zhu Ping , Wei Jianfeng , Lu Jin , Yuan Chaozhe
Published: August 2024

The dredging pump is the most critical dredging equipment for the cutter suction dredger, and its performance is one of the decisive factors for the cutter suction dredger productivity. Relying on the Xiamen New Airport Phase II Project, a comparative analysis of the dredging pump performance before and after impeller wear was carried out under medium-coarse sand conveying conditions. The results show that impeller wears will cause the dredging pump head to fall and performance degradation. In the range of normal construction process parameters, the larger the impeller rotational speed is or the smaller the concentration of medium-coarse sand conveying is, the more significant the decline in dredging pump performance will be. The research results can provide guidance for the cutter suction dredger pump working point adjustment and process optimization in the dredging pump wear condition.
Optimization of braking noise caused by eccentric wear of friction plates based on response surface method
Authors: Zhang Xuesong , Jiao Quanwei
Published: August 2024

Given the noise caused by the friction plate of wear, the finite element model of the brake after eccentric wear of the friction pad was established, and the complex eigenvalue method was used to analyze the influence of eccentric wear of friction pads on braking noise. The value range of brake material parameters is determined by a single-factor test, and the response surface approximate model was constructed to reduce the TOI value of the vibration tendency coefficient. The results show that the braking noise tends to increase with the increase of the eccentric wear of the friction plate. After material parameter optimization, the vibration tendency coefficient of the eccentric wear brake is reduced by 66.2%, and the vibration tendency coefficient of the new brake is reduced by 36.8%. The conclusion provides some basis for the design of the brake.
Damage identification of simply-supported beams based on SD value method
Authors: Li Yiming , Liu Qiyang , Geng Jiangwei , Wang Yang
Published: August 2024

Combining the relationships among the displacement mode, rotation mode, and curvature mode, this study proposes a structural curvature variance ratio (SD) method that can simplify the calculation and reduce the damage recognition error. Using beam structures in the western region as an example, a finite element model is established, and the impact of the displacement modulus on beam damage recognition is analyzed. The applicability of the SD method for damage recognition is also investigated. In the presence of measurement errors, the SD method and the curvature modulus difference method are compared and analyzed. The results show that this method can effectively identify structural damage, determine the location and quantity of local damage, and simplify calculations while reducing error transmission and amplification.
Additional outpatient expenditures due to heatwaves: evidence from the Chinese older population
Authors: Li Weilong , Liao Hua , Zeng Hongmei , Zhang Ying
Published: August 2024

As global temperatures rise, the impact on health becomes increasingly apparent, especially for vulnerable seniors. This study analyzed the additional financial burden caused by heatwaves on outpatient healthcare spending among China’s older people, using data from the China Health and Retirement Longitudinal Study (CHARLS) covering 126 cities between 2011 and 2018. Applying generalized estimating equations (GEE) models and incorporating local weather data, we examined the data from 22 023 questionnaires. The findings show that each heatwave in the past 30 d increased individual outpatient costs by 2.29 CNY (95% CI: 0.31–4.27), affecting individuals with chronic diseases, those without air conditioning, and those in rural areas more severely. Naps proved effective in mitigating heatwave effects. Projections suggest that in the summer of 2050, under the SSP5-8.5 scenario, additional healthcare expenses attributable to rising temperatures might reach 29.14 billion CNY (95% CI: 3.94–54.33). These findings highlight the urgent need for proactive heat and health strategies in China and support naps as a protective measure against heat-induced health risks for older people.
Generalized parity-oblivious communication games powered by quantum preparation contextuality
Authors: Roy Prabuddha , Pan A K
Published: August 2024

The parity-oblivious random-access-code (PORAC) is a class of communication games involving a sender (Alice) and a receiver (Bob). In such games, Alice’s amount of communication to Bob is constraint by the parity-oblivious (PO) conditions, so that the parity information of her inputs remains oblivious to Bob. The PO condition in an operational theory is equivalently represented in an ontological model that satisfies the preparation noncontextuality. In this paper, we provide a nontrivial generalization of the existing two-level PORAC and derive the winning probability of the game in the preparation noncontextual ontological model. We demonstrate that the quantum theory outperforms the preparation noncontextual model by predicting higher winning probability in our generalized PORAC.
A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field for fixed boundary equilibria
Authors: FARENGO Ricardo , GARCÍA-MARTÍNEZ Pablo L , FERRARI Hugo E
Published: August 2024

A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field consistent with a given internal magnetohydrodynamic (MHD) equilibrium and coil geometry is presented. The constrained optimization technique employed allows to fix the exact position of the X-points. The external poloidal flux and field are calculated using Green’s functions expressed in terms of elliptic integrals that are calculated using a fast and accurate routine. The calculation can be limited to the region between the plasma and the device wall. An example for a double null configuration is presented.
Lycium ruthenicum stem extract mediated green synthesis of MnO2/Mn3(PO4)2 composite nanowire electrocatalyst for oxygen evolution reaction
Authors: Kumar Raj , Raj Ritu , Ahmed Imtiaz , Kumar Vikash , Singh Gajendra Prasad , Haldar Krishna Kanta
Published: August 2024

A composite of manganese oxide (MnO2) and Mn3(PO4)2 decorated nanowires (MnO2/Mn3(PO4)2) was prepared using Lycium ruthenicum stem-extract mediated green synthesis. This composite material functions as an efficient and long-lasting electrocatalyst for water-splitting reactions, which could significantly improve the performance of oxygen evolution reaction (OER). The OER activity of MnO2/Mn3(PO4)2-based nanowires is boosted by blending with a conducting support, such as manganese oxide (MnO2). The x-ray diffraction pattern and Fourier transform infrared data indicate that the nanowires are highly crystalline. The MnO2/Mn3(PO4)2 composite material demonstrates superior stability compared to its individual constituents and generates a current density of 10 mA cm−2 at a low overpotential of 244 mV for OER in alkaline media. This research may lead to the development of MnO2/Mn3(PO4)2 composite materials as electrocatalysts for overall water-splitting reactions.
Dwelling Love
Authors: Swanton Christine
Published: August 2024

In this chapter I show that the various loves of other and self should be integrated with “dwelling” love, a form of love that Heidegger claims is foundational in all our loves. The integration has two aspects. First, dwelling love is not simply a love of nature: it is a love of nature as a dwelling place, a place where individual humans and other beings that are objects of love, dwell. Love of “nature” cannot swamp self-love and love of others. Second, love of self and other cannot be abstracted away from our being situated in our dwelling place. For Heidegger to dwell is to be and feel “at home” in one’s day to day life. At the core of dwelling love is an emotional construal of appropriate things as ‘holy’ or somehow sacred. Construing as holy is the fundamental Grundstimmung of dwelling love.
Alfonso Reyes
Authors: Barrera Enderle Víctor
Published: August 2024

The work of Alfonso Reyes represents a watershed in modern Hispano-American literature thanks not only to his contributions to the genres of essays and poetry, but also his role in the process of specialization of the role of the writer and intellectual in the public sphere. His path represents a shift from the 19th-century “man of letters” to the modern intellectual. Alfonso Reyes was part of the Ateneo de la Juventud generation (the first modern intellectual association in Mexico), and after these formative years, he took on (and reformed) the main literary currents of Hispano-American modernism and complemented them with the underlying concerns of his generation, such as the search for professionalization in literature and the creation of modern cultural and educational policies.
Digital Platform Innovation and Opportunities
Authors: Madsen Tammy L.
Published: August 2024

Multi-sided digital platform (MSDP) business models have enabled the reorganization of industries and are fundamentally changing the way firms innovate and grow. Fueled by advances in digital technology, digital platform firms such as Apple, Alibaba, Amazon, Google, Tencent, and ByteDance have gained prominence around the globe. MSDPs create value by facilitating interconnections of products, services, or systems generated by a variety of external actors, thereby enabling them to interact in ways that otherwise might be elusive. Theoretical and empirical work on digital platforms also has accelerated in recent decades. Scholars have explored a variety of topics such as platform competition, network effects and their implications, platforms and corporate scope (i.e., vertical integration into complementary offerings), platform types, complementor heterogeneity, and platform governance and ecosystem orchestration. Much of the empirical literature directs attention to the economics of platforms at the exclusion of analyzing how differences in strategic objectives and choices contribute to unique MSDP positions within an ecosystem.

Heterogeneity in strategic objectives contributes to variation in platform scope, governance practices, and potential externalities and thus influences the strategic and organizational benefits accruing to participating actors and the platform itself. It follows that analyzing platforms from a strategic view can help to identify innovations in MSDPs and their governance.

In one novel MSDP model, the co-innovation platform, the primary strategic objective is accelerating innovation and ecosystem growth by enabling collaboration among a wide array of diverse external actors. Aligned with a focus on the quality of collaborations, one of a co-innovation MSDP’s distinguishing value creation features is its hands-on approach to the formation and execution of co-innovation partnerships. This hands-on approach relies on different governance choices and yields a different mix of strategic and organizational benefits for partners and the platform relative to the hands-off approach employed by most MSDPs. Many opportunities exist for advancing theory and empirical work on the implications of platform heterogeneity.
Lateralization of Brain Function
Authors: Rogers Lesley J.
Published: August 2024

The left and right hemispheres of the brain process sensory information in different ways and function differently in controlling behavior. This lateralization of brain function, originally thought to be unique to humans, is now known to occur in a broad range of non-human vertebrates and even in invertebrates, indicating that it is an essential feature of both large and small brains. Some evidence indicates that lateralization of brain function improves cognitive capacity of the brain. Many, often unrelated, brain functions are lateralized. In humans, these include differential specialization of the hemispheres to process language and produce speech, express emotions, respond to faces, attend to spatial information, and control hand use. As now clear for handedness, both genetic expression and environmental influences are involved in complex ways. Since lateral division of function in the brains of non-human animals has sufficient similarity to that of humans, it is probable that at least some asymmetries were evolutionary precursors to language and speech.

It is notable that lateralization is in no species totally in a single direction. Some evidence from studies of animal species provides support for the hypothesis that alignment of laterality in most individuals in a species occurs only for control of behavior that requires one lateralized individual to interact with another lateralized individual (i.e., in social interaction). In humans, individuals with non-right-handedness (left-handed and mixed-handed) are more prone to a number of psychiatric conditions or other behavioral conditions, including autism, schizophrenia, and dyslexia.
Representing Masculinities in Children’s Literature Series
Authors: Potter Troy
Published: August 2024

Children’s literature operates as discursive social structures that establish young readers’ understanding of gender, including masculinities. Oftentimes, however, children’s literature perpetuates limited or normative constructions of gender. This is particularly the case for two genres that are popular with male readers: fantasy and comedy. Both genres for young readers contribute to the maintenance of a hegemony of masculinity that values independence, action, resourcefulness, and bravery.While some fantasy and comedy series for young readers begin to expand the repertoire of acceptable masculine traits by incorporating empathy and consideration of others, validating more sensitive models of masculinity, they do not necessarily undermine the hierarchy seemingly inherent to masculine dynamics. By understanding the complex and sometimes contradictory messages about masculinity that are presented in books for young people, educators can develop critical ways of reading fiction to engage children in meaningful conversations about gendered identities in order to promote acceptance and understanding of all genders and differences, not just those relating to masculinities.
Textiles in West Africa up to the 20th Century
Authors: Benjamin Jody
Published: August 2024

Across the large, dynamic diverse space of West Africa—from the dense urban enclaves in Oyo, Kano, Kumasi, Jenne, and Timbuktu to the smaller towns and village settings of the Sahel or rainy tropics of the southern coast—textiles were important to the social, economic, religious, and cultural lives of local communities. In many parts of the region south from Lake Chad to the Bight of Biafra and west along the Atlantic coast to Mauritania, artisans have processed and woven textiles from raffia, bark, bast, wool, silk, and cotton that was used for clothing such as infant swaddling, wrappers, head ties, turbans, tunics, gowns, trousers, and burial cloths. Textiles have served a variety of utilitarian and ceremonial purposes such as a flexible form of exchange currency to pay a customs tax or to give as a dowry in marriage. Whether as artifacts of everyday use or exceptional splendor, West African textiles have reflected the region’s enormous historical, geographical, ethnic, and religious diversity, as well as the specificity of distinct areas and time periods. Archeologists, art historians, anthropologists, and historians have produced much scholarly literature on cloth both manufactured in and imported to West Africa. These works have debated the still imprecisely understood origins of cloth weaving in West Africa, the use of natural dyes, and the impact of the capitalist global economy that began to emerge in the 18th and 19th centuries on local textile manufacturing and consumers. The study of textiles, especially their circulation and use before the 20th century, challenges the notion of West African societies as either static or isolated from the evolving global scene.
The Stone Age of the Congo Basin
Authors: Cornelissen Els
Published: August 2024

The Stone Age in the Congo Basin has a rich yet troubled research tradition. During the colonial era, prehistory was high on the research agenda in search of ancient sites yet slipped into the background within the context of postcolonial states focusing on recent history and the last five thousand years. In archaeological terms, attention shifted from flaked stone to pottery and iron as material traces of the past. Issues with site integrity and lack of absolute chronology imply that often the identification of the various phases of the Stone Age, as well as of cultures and industries, is essentially based on typo-technological characteristics.

A clear challenge both for studying and for occupation during the Stone Age in the Congo Basin is the rainforest. Though poorly documented at the time of Stone Age occupations, the last twenty-five hundred to four thousand years yield a very dynamic picture of this once-thought immutable biome.

Despite all methodological and factual caveats and the disparity of the archaeological record in terms of chronological, typo-technological, behavioral, and environmental characteristics, there can be no doubt about the flexibility and adaptability of human populations and their ancestors in the Congo Basin. The field of genetic studies is increasingly contributing to understanding this fascinating human history of rainforest occupation.
African Economies in the Late Colonial Period, c . 1945–1960
Authors: Hillbom Ellen
Published: August 2024

During the late colonial era, the focus of economic strategies was on supporting the export sectors dominated by cash-crop production and extractive industries. While the empires paid for the postwar reconstruction of the European metropoles, colonies also experienced economic growth. Increasing incomes and changing consumption patterns created some opportunities for local agro-processing, manufacturing, and services, but there were few larger initiatives for diversification of the colonial economies. Growth was extensive rather than intensive, and the reliance on a small number of commodities made the economies vulnerable to fluctuating world market prices.

The colonial budgets grew due to increasing tax revenues and more generous grants and loans from the metropoles. Subsequently, there was increasing government spending on administration, infrastructure, and human development. Urbanization led to substantial social transformation with new types of occupations, changing consumption patterns, unionization, and new relationships between the urban populations and the emerging African political leadership. With an expanding wage sector and opportunities for engaging in export-oriented commercialization, there was growing differentiation and increasing income inequality. Finally, living standards also improved through better hygiene and healthcare, housing, infrastructure, and other investments in social development.
Post-Apartheid Memorialization in South Africa
Authors: Roux Naomi
Published: August 2024

Public memory and memorialization were a realm of significant change in the aftermath of the fall of apartheid in South Africa. Memorialization processes, particularly in the late 1990s and first decade of the 2000s, were closely linked with constructions of new national identities, narratives, and meanings. The Truth and Reconciliation Commission process of the late 1990s was particularly crucial in bringing suppressed narratives of memory and trauma to light, and strongly influenced the production of memory and memorialization in this period.

Postapartheid memorialization took several forms, including the funding and construction of large-scale national projects for new museums and heritage sites. In some instances, these state-led projects were enfolded with ambitions of urban remaking, or were positioned as drivers of social and economic development. At the same time, the postapartheid period saw a burgeoning of smaller, community-driven projects of memory that tended to make use of more open-ended narratives and methodologies to engage the complexities of memory, particularly around instances of forced removals and collective traumas within communities.

While the construction of new museums and memorials were crucial to postapartheid memorialization processes, there has also been a strong drive to transform and reformulate existing museums and places of memory. These processes include the establishment of the Southern and Northern Flagship Institutions, which restructured the functioning of national museums and their approaches. Sites closely linked with histories of Afrikaner Nationalism have, in some instances, attempted to present reconfigured narratives focusing on cultural presence rather than nationalist politics, while many smaller museums have struggled to develop more inclusive and reflective approaches. In the first decades of the 21st century, the persistence of heroic and monumental forms of memory-making and of colonial memorials has been called into question via the Rhodes Must Fall movement and ongoing calls for a more radical remaking of public memory.
Trans-Saharan Trade
Authors: Scheele Judith
Published: August 2024

Trade in the Sahara is as old as its current human occupation. The many different and often highly specialized ways in which Saharans have pursued their livelihoods since the region developed its current hyper-aridity roughly three thousand years ago, from settled agriculture to pastoral nomadism via intermediate forms, all fundamentally rely on mobility and exchange over short, medium, and long distances. Oases were established to facilitate trade, but they could not survive without sustained exchange with pastoral and trading economies. Pastoral nomads relied on sedentary outlets in their economic and migratory cycles. This simple observation has several implications for trans-Saharan trade: One, although historical periods can be identified when trans-Saharan trade visibly increased, in particular areas and for historically specific reasons, it is difficult and probably counterproductive to search for the origins of trans-Saharan trade as such. Two, the kind of trade that is most familiar from Arabic and European sources—namely, the trade in trans-Saharan luxuries—was only the tip of the iceberg of more stable patterns of exchange, much of which concerned rather mundane staples such as cereals, salt, and dates. The decline of visible, trans-Saharan trade at any particular moment and in any particular place hence does not imply the decline of all forms of Saharan trade. Three, thinking needs to extend beyond north–south axes, so that patterns of connectivity—which might just as easily stretch east or west—can be analyzed in their own terms. Four, all trade should not be assumed as necessarily trans-Saharan, that is to say, carrying goods produced beyond the Sahara across it to the other side, but Saharan production and consumption, also with regards to the enslaved, need to be taken into account. In turn, this means that Saharan trade should not be conceived of as in any way external to Saharan societies but as part and parcel of broader political, social, and economic logics, where calculations of material profits were not always the main driving force. Kin ties and marital alliances, and hence women, played major parts in this. Much of this is still true today, allowing transregional practice of exchange to continue in new forms, despite profound technological changes—from camel caravans to trucks—and the contemporary economic and political weight of postcolonial nation-states and their borders throughout the region. The current criminalization of all trans-Saharan activities, mostly through foreign military or diplomatic intervention, therefore cannot but have disastrous consequences for the region as a whole.
Warfare among Yoruba in the Nineteenth Century
Authors: Usman Aribidesi
Published: August 2024

One cannot discuss the 19th-century Yoruba warfare without emphasizing some of the pre-19th-century events that led to the wars. Military aggression among Yoruba in the 19th century was an escalation of the political and economic turmoil in Yorubaland during the previous century. Critical questions are: What caused warfare in Yorubaland in the 19th century or earlier? Did the wars lead to socio-political changes in Yorubaland? Yoruba wars can be identified with three, though not widely distinct, periods: 1750 to 1837, 1837 to 1878, and 1878 to 1893. In the first period, Nupe intensified their raids in northern Yoruba as the constitutional crisis in Old Oyo began to distract the administration and reduced Old Oyo’s control in the north. In the south, Yoruba were gripped by the Owu-Ife war and, later, the Ijebu-Ife-Old Oyo military coalition against Owu. The second period began with the collapse of Old Oyo and the struggle for leadership among the successor states of Ibadan, Ijaye, and Ilorin. The third and last period of warfare saw a military alliance against Ibadan. The oppressive regime of Ibadan led to a revolt among the subjugated towns that formed the Ekitiparapo confederacy.

Warfare and military threat in Yorubaland have led to aggregated communities, the manufacturing of weapons of war, the construction of fortifications, and the abandonment and settlement relocation. Warfare in Yorubaland gave rise to both conqueror states and small, fragmented, conquered polities. Constant military pressure from north and south transformed Old Oyo into a militant state. The collapse of Old Oyo in the 19th century ushered in a long period of Yoruba internecine warfare. The unrest destroyed many royal households, which gave able warriors opportunities to gain wealth and power.
Prophets and Prophecy in Eastern Africa, 1800–1950
Authors: Waller Richard
Published: August 2024

The article covers the history of prophets and prophecy in Eastern Africa in the 19th and 20th centuries, up to Independence. It divides the field into two contrasting zones of interest that can be usefully compared. One includes the southern Sudan, northeast Uganda, and Kenya; the other has parts of southern Malawi and northern Zambia. Earlier attempts to write on this topic have been baffled by conceptual and terminological difficulties—what exactly are prophets?—and the earlier predominance of sociological enquiry that assumed that “politics” rather than “religion” should be the focus. This article stresses the importance of understanding the “religious” aspect of prophecy and the allegiance to prophets. Prophets and their followers were driven by their awareness of the presence of spiritual agents who intervened in human affairs and with whom communication was possible—without an understanding of this, analysis fails. The article also considers prophets’ followings and the study of prophecy (as a separate topic).
Head, Bessie
Authors: Driver Dorothy
Published: August 2024

Bessie Head (b. 1937–d. 1986), claimed as a national literary figure by both South Africa and Botswana, has acquired an international reputation for pathbreaking postcolonial explorations of individual, social, and psychic life. Texts published in her lifetime include three novels, a volume of short stories, and two revisionist histories of Botswana, as well as stories, sketches, essays, poems, and reviews in journals and anthologies. Most of the latter, along with a novella, selected correspondence, and other previously unpublished work, have been posthumously gathered into book-length collections and journal sections. Her most widely celebrated (and most challenging) novel is A Question of Power (1974), with Maru (1971) a close second, but other writing also receives continuing attention.

Born in South Africa to a nonmarital, “mixed-race” union, Bessie Amelia Emery grew up in foster and orphanage care, thereafter working as a teacher and a journalist. After marrying fellow journalist Harold Head and bearing their child, she relocated in 1964, as a single parent, to the then Bechuanaland, now Botswana, where she earned a meager living from writing and market-gardening while dealing with psychological ill health. Although freed from apartheid South Africa and its near overwhelming stranglehold on creativity, her writing frequently recurs to its currents of insult, abuse, and degradation. Botswana offered her a more humane environment, despite problematic race and gender relations. Drawn from her transnational experience, her deftly crafted narratives provide a sustained social critique of the dynamics of power and its intersecting subordinations without descending into crude identity politics, thus formulating what may be called a transnational black aesthetic. Boldly transgressing genre, Head foregrounds the role of creativity, individual and social, as she reimagines a world more hospitable than even her Botswana experience could provide. Into this newly imagined world, the writer resituates and redefines herself, formulating a life-in-writing and a reality-to-come.
Quasi Maximum Likelihood Estimation of High-Dimensional Factor Models
Authors: Barigozzi Matteo
Published: August 2024

Factor models are some of the most common dimension reduction techniques in time series econometrics. They are based on the idea that each element of a set of N time series is made of a common component driven by few latent factors capturing the main comovements among the series, plus idiosyncratic components often representing just measurement error or at most being weakly cross-sectionally correlated with the other idiosyncratic components. When N is large the factors can be retrieved by cross-sectional aggregation of the observed time series. This is the so-called blessing of dimensionality, meaning that having N growing to infinity poses no estimation problem but in fact is a necessary condition for consistent estimation of the factors and for identification of the common and idiosyncratic components.

There exist two main ways to estimate a factor model: principal component analysis and maximum likelihood estimation. The former method is more recent and more common in econometrics, but the latter, which is the classical approach, has many appealing features such as allowing one to impose constraints, deal with missing values, and explicitly model the dynamic of the factors. Maximum likelihood estimation of large factor models has been studied in two influential papers: Doz et al.’s “A Quasi Maximum Likelihood Approach for Large Approximate Dynamic Factor Models” and Bai and Li’s “Maximum Likelihood Estimation and Inference for Approximate Factor Models of High Dimension.” The latter considers the static case, which is closer to the classical approach and no model for the factors is assumed, and the former is more general: it considers estimation combined with the use of Kalman filtering techniques, which has grown popular in macroeconomic policy analysis.

Those two papers, together with other recent results, have brought new asymptotic results for which a synthesis is provided. Special attention is paid to the set of assumptions, which is taken to be the minimal set of assumptions required to get the results.
Spices in Cuisines and Cookbooks
Authors: Albala Ken
Published: August 2024

Spices are defined in culinary terms as plant products such as roots, bark, stems, seeds, and other parts, usually dried, which have been historically important in recipes around the world and in global trade. Because they traveled great distances and went through the hands of many different merchants, they were often extremely expensive and a perfect marker of status in medieval and Renaissance European cooking. They were also considered medicinal and perfect for balancing the humors. Pepper, ginger, and cloves, for example, were categorized as hot because they left a burning sensation on the tongue and presumably in the body as well, so ideal for counteracting cold imbalances. The height of the spice trade into Europe was the late Middle Ages into the 17th century, handled primarily by the Venetians, Portuguese, and then Dutch in turn. Their decline in popularity may be attributed to the advent of classical French haute cuisine, in which it was thought that food should taste of itself and not be adorned with complex exotic flavorings. Because they were imported in greater volume, they also lost their power as a marker of status and were generally relegated to the end of meals, along with sugar, or were used in moderate amounts. The only major spice to remain on the table in the early 21st century is pepper.
Food in the Medieval Islamic World (9th–15th Centuries)
Authors: Newman Daniel
Published: August 2024

The medieval Islamic world boasts a rich tapestry of culinary traditions reflecting the diverse cultures that make up the region. This period saw the introduction of significant changes in dietary practices, food culture, and foodways.

As the Islamic Empire expanded, it became a trading hub, introducing spices and culinary practices from across the known world. During the Abbasid caliphate, culinary literature emerged, showcasing a sophisticated cuisine that is arguably the richest of the Middle Ages. Surviving works originated in an area spanning from Muslim Spain (al-Andalus) to the Near East (Mashriq) and reveal the importance attached to the culinary arts and gastronomy in elite circles. The cuisine was inextricably linked with medicine, with an emphasis on the health benefits of ingredients and dishes.

Culinary texts also reveal the sophisticated kitchen equipment and tableware available and the attention paid to presentation. There was a structured approach to dining that started with appetizers and progressed to more substantial dishes, often involving complex flavors and cooking techniques. Religious teachings also influenced dietary practices, with prohibitions on certain foods and an emphasis on moderation.

The culinary treatises provide insights into the interconnection of food, culture, and religion in the medieval Islamic world, showing how culinary practices were influenced by trade, geography, and religious teachings, whereas the emphasis on gustatory sensation, health, and etiquette reflects the rich cultural heritage and the significant role food played in the social and religious fabric of medieval Islamic societies.
A History of Latino/as and Sports
Authors: Alamillo José M.
Published: August 2024

Before the arrival of Europeans, Mesoamerican indigenous populations participated in various ball games that served some form of cultural and religious ritual. In an effort to suppress indigenous traditions, Spaniards introduced colonial sporting practices using animals. In the 19th century, British merchants brought cricket, soccer, and tennis to South America and the Caribbean, and occupying US soldiers disseminated baseball and other modern sports throughout Latin America. During the early 20th century, Latino/a immigrants and their children embraced European and American sporting practices, but they also used sports to express cultural and ethnic pride while rejecting Euro-American patronizing messages. As the financial crisis and anti-immigrant anxieties worsened during the Great Depression, sports took on a more political meaning to combat negative stereotypes. With professional sports coming to a halt, Latino/a organizations stepped up efforts to organize amateur athletic competitions. Their fight for equality in sports became more visible after World War II when they sacrificed their lives abroad only to return home to limited opportunities in jobs, education, and politics. During the 1960s civil rights movement, Latino/as used sports as a platform to speak about the social injustices their communities faced. The dramatic growth of the US Latino population since 1980 has alerted sports industry leaders that Latino/a fans and athletes are the future of US sports. Into the 21st century, Latino/as will continue to use sports to assert their identity while stressing their community’s integral place within American society.