bluuebunny/crossref_metadata_2025 huggingface dataset:
A two-dimensional piezoelectric traveling wave generator using a multi-integer frequency, two-mode method (MIF-TM)
Authors: Hsu Yu-Hsiang , Lin Yu-Min , Lee Chih-Kung
Published: October 2021

In this paper, we report a new method called a multi-integer frequency, two-mode (MIF-TM) to generate multi-directional traveling waves on a square plate. The uniqueness of this driving method is threefold. Firstly, as the two driving frequencies are at or near resonant frequencies of the two bending modes, the driving efficiency can be largely enhanced by using structural resonance. Secondly, as the two actuating areas can sufficiently induce traveling waves, each of them is driven by one of the two driving frequencies. It is possible to generate steady traveling waves by making the two driving frequencies possess a multi-integer relationship and with a phase difference. Thirdly, the direction of the traveling wave can be controlled to propagate toward either the x- or y-direction by designing the location and size of the actuating area. To assist in the design of the MIF-TM traveling wave generator, an analytical model was derived to depict the induction of the traveling waves. Using this analytical model, we designed a piezoelectric traveling wave generator with weight of 2.35 g, dimension of 45 × 45 × 0.4 mm piezoelectric bimorph with four designated electrode pairs. It was verified to be either in the positive or negative direction traveling wave as it was controlled by adjusting the phase difference between the two driving frequencies. Our experimental results demonstrated that the generated x-direction traveling wave can move a 0.3 g object at a speed of 1.48 mm s−1, and the generated y-direction travel wave can move this same object at a speed of 1.36 mm s−1. The design, numerical analysis, finite element analysis, and experimental studies are detailed in this paper.
Experimental characterization and modular modeling of hystereses for smart material actuators
Authors: Yi Sicheng , Zhang Quan , Xu Liang , Wang Tianhong , Li Long
Published: October 2021

In this article, we present a novel modular modeling approach to describe the hystereses for piezoelectric, magnetostrictive and shape memory alloy (SMA) actuators. For the above actuators, the output vs. input loops exhibit varying hystereses under the input signals of the different frequencies and amplitudes. To this end, the experimental characterization is conducted and hysteresis modeling approach is studied. Two characteristic indexes, i.e. loop relative width, loop asymmetry coefficients, are quantitatively analyzed according to the open-loop experiments for the three actuators. Based on the hysteresis phenomenon analyses, different submodels are selected to describe those phenomena. The Prandtl-Ishlinskii submodel is applied for symmetry rate-independent hysteresis identification; the arctangent-polynomial modified Prandtl-Ishlinskii submodel is proposed for asymmetry rate-independent hysteresis identification; infinite impulse response submodel is used for rate-dependent hysteresis identification. Those submodels are selected to construct a cascaded overall model to describe the hysteresis of piezoelectric, magnetostrictive, and SMA actuators. The hysteresis experimental identification results show that, with the proposed phenomenon-based hysteresis modular modeling approach, better performance can be obtained in terms of modeling accuracy and computation time than some other approaches.
Hydrodynamic response time of magnetorheological fluid in valve mode: model and experimental verification
Authors: Kubík M , Šebesta K , Strecker Z , Jeniš F , Goldasz J , Mazůrek I
Published: October 2021

The transient behaviour of magnetorheological (MR) actuators affects their performance in progressive semiactive control suspension systems. The two sources of the time delay between the control signal and damping force are (a) dynamics of MR damper hardware and (b) the MR fluid dynamics. The significant part of the MR fluid response time is the so-called hydrodynamic response time which is connected with the transient flow. Due to the above, the main aim of this paper is to experimentally determine the hydrodynamic response time of MR fluid and present systematic means for characterizing it via computational fluid dynamics (CFD) or analytical tools. The unique measurement method using an in-house patented slit flow rheometer is presented. The essence of the method relies on determining the pressure drop variation with the time spent by the fluid in the MR gap. The experimental determined hydrodynamic response time of MR fluid ranges from 0.4 to 1 ms for a selected gap size and a range of magnetic field stimuli. The results show that the higher the magnetic field, the lower the hydrodynamic response time is. Both CFD and analytical models exhibit similar trends as the experimental data. Moreover, the impact of temperature and gap size was determined. Here, the higher the gap size and temperature of MR fluid, the longer the response time is.
Exceptional points in a topological waveguide-cavity coupled system
Authors: Dong Junhua , Hu Qingmei , Ji Chang-Yin , Zou Bingsuo , Zhang Yongyou
Published: October 2021

Exceptional points (EPs) as branch singularities describe peculiar degeneracies of non-Hermitian systems, widely studied in topological and non-topological optical architectures with introducing gain or loss technically. This work focuses on the EPs in a topological waveguide (TW)-cavity coupled structure, where there is no need to introduce practical gain or loss. The topological cavity contains two degenerate counter-propagation topological whispering gallery modes, whose coupling with the TW leads to the effective gain and loss, responsible for the EP. Such a photonic architecture is designed practically by crystal-symmetry-protected topological photonic insulators based on air rods in conventional dielectric materials. The relevant EP reveals the breaking of the parity-time symmetry, reflected by the change of the transmission-dip number in the optical transmission spectra of the system. Achieving EPs in topological photonic systems possibly opens a new avenue toward robust optical devices with exceptional-point-based unique properties and functionalities.
Fitting ultracold resonances without a fit
Authors: Simoni A
Published: October 2021

We present a numerical procedure allowing one to extract Feshbach resonance parameters from numerical calculations without relying on approximate fitting procedures. Our approach is based on a simple decomposition of the reactance matrix in terms of poles and residual background contribution, and can be applied to the general situation of inelastic overlapping resonances. A simple lineshape for overlapping inelastic resonances, equivalent to known results in the particular cases of isolated and overlapping elastic features, is also rigorously derived.
Multi-messenger emission from the parsec-scale jet of the flat-spectrum radio quasar PKS 1502+106 coincident with high-energy neutrino IceCube-190730A
Authors: Oikonomou Foteini , Petropoulou Maria , Murase Kohta , Tohuvavohu Aaron , Vasilopoulos Georgios , Buson Sara , Santander Marcos
Published: October 2021

On July 30th, 2019 IceCube detected a high-energy astrophysical muon neutrino candidate, IC-190730A with a 67% probability of astrophysical origin. The flat spectrum radio quasar (FSRQ) PKS 1502 +106 is in the error circle of the neutrino. Motivated by this observation, we study PKS 1502+106 as a possible source of IC-190730A. PKS 1502+106 was in a quiet state in terms of UV/optical/X-ray/γ-ray flux at the time of the neutrino alert, we therefore model the expected neutrino emission from the source during its average long-term state, and investigate whether the emission of IC-190730A as a result of the quiet long-term emission of PKS 1502+106 is plausible. We analyse UV/optical and X-ray data and collect additional observations from the literature to construct the multi-wavelength spectral energy distribution of PKS 1502+106. We perform leptohadronic modelling of the multi-wavelength emission of the source and determine the most plausible emission scenarios and the maximum expected accompanying neutrino flux. A model in which the multi-wavelength emission of PKS 1502+106 originates beyond the broad-line region and inside the dust torus is most consistent with the observations. In this scenario, PKS 1502+106 can have produced up to of order one muon neutrino with energy exceeding 100 TeV in the lifetime of IceCube. An appealing feature of this model is that the required proton luminosity is consistent with the average required proton luminosity if blazars power the observed ultra-high-energy-cosmic-ray flux and well below the source's Eddington luminosity. If such a model is ubiquitous among FSRQs, additional neutrinos can be expected from other bright sources with energy ≳ 10 PeV.
AGN Lifetimes in UV-selected Galaxies: A Clue to Supermassive Black Hole-galaxy Coevolution
Authors: Lin Xiaozhi , Xue Yongquan , Fang Guanwen , Fan Lulu , Le Huynh Anh N , Ayubinia Ashraf
Published: October 2021

The coevolution between supermassive black holes (SMBHs) and their host galaxies has been proposed for more than a decade, albeit with little direct evidence about black hole accretion activities regulating galaxy star formation at z > 1. In this paper, we study the lifetimes of X-ray active galactic nuclei (AGNs) in UV-selected red sequence (RS), blue cloud (BC) and green valley (GV) galaxies, finding that AGN accretion activities are most prominent in GV galaxies at z ∼ 1.5–2, compared with RS and BC galaxies. We also compare AGN accretion timescales with typical color transition timescales of UV-selected galaxies. We find that the lifetime of GV galaxies at z ∼ 1.5–2 is very close to the typical timescale when the AGNs residing in them stay in the high-accretion-rate mode at these redshifts; for BC galaxies, the consistency between the color transition timescale and the black hole strong accretion lifetime is more likely to happen at lower redshifts (z < 1). Our results support the scenario where AGN accretion activities govern UV color transitions of host galaxies, making galaxies and their central SMBHs coevolve with each other.
Status of the DOM electronics
Authors: Real D. , Calvo D. , van Beveren V. , Musico P. , Pellegini G. , Jansweijer P. , Colonges S. , Chiarusi T. , Bozza C. , Nicolau C. , Díaz A. , Filippini F. , Benfenati F.
Published: October 2021

The KM3NeT collaboration has already produced electronics to assemble more than one thousand digital optical modules, which have started to be deployed at the bottom of the Mediterranean Sea. An upgrade of the electronics is currently underway, expecting to have a revision of it by end of 2021. Here we describe the main improvements added to the digital optical module electronics, including the new high reliability transceiver in the central logic board and the increased efficiency in the power board.
Self-financed marine protected areas
Authors: Millage Katherine D , Villaseñor-Derbez Juan Carlos , Bradley Darcy , Burgess Matthew G , Lenihan Hunter S , Costello Christopher
Published: October 2021

Marine protected areas (MPAs) are an important tool for conservation but can be victims of their own success—higher fish biomass within MPAs create incentives to poach. This insight underpins the finding that fishing persists in most MPAs worldwide, and it raises questions about MPA monitoring and enforcement. We propose a novel institution to enhance MPA design—a ‘Conservation Finance Area (CFA)’—that utilizes leased fishing zones inside of MPAs, fed by spillover, to finance monitoring and enforcement and achieve greater conservation success. Using a bioeconomic model we show that CFAs can fully finance enforcement, deter illegal fishing, and ultimately maximize fish biomass. Moreover, we show that unless a large, exogenous, and perpetual enforcement budget is available, implementing a CFA in a no-take MPA would always result in higher biomass than without. We also explore real-world enabling conditions, providing a plausible funding pathway to improve outcomes for existing and future MPAs.
Quantum pattern recognition in photonic circuits
Authors: Wang Rui , Hernani-Morales Carlos , Martín-Guerrero José D , Solano Enrique , Albarrán-Arriagada Francisco
Published: October 2021

This paper proposes a machine learning method to characterize photonic states via a simple optical circuit and data processing of photon number distributions, such as photonic patterns. The input states consist of two coherent states used as references and a two-mode unknown state to be studied. We successfully trained supervised learning algorithms that can predict the degree of entanglement in the two-mode state as well as perform the full tomography of one photonic mode, obtaining satisfactory values in the considered regression metrics.
Theory of perturbation of electric potential by a 3D object made of an anisotropic dielectric material
Authors: Lakhtakia Akhlesh , Alkhoori Hamad M , Tsitsas Nikolaos L
Published: October 2021

The extended boundary condition method (EBCM) was formulated for the perturbation of a source electric potential by a 3D object composed of a homogeneous anisotropic dielectric medium whose relative permittivity dyadic is positive definite. The formulation required the application of Green’s second identity to the exterior region to deduce the electrostatic counterpart of the Ewald–Oseen extinction theorem. The electric potential inside the object was represented using a basis obtained by implementing an affine bijective transformation of space to the Gauss equation for the electric field. The EBCM yields a transition matrix that depends on the geometry and the composition of the 3D object, but not on the source potential.
Sympathy and Empathy
Authors: Greiner Rae
Published: October 2021

Sympathy and empathy are complex and entwined concepts with philosophical and scientific roots relating to issues in ethics, aesthetics, psychology, biology, and neuroscience. For some, the two concepts are indistinguishable, the two terms interchangeable, but each has a unique history as well as qualities that make both concepts distinct. Although each is associated with feeling, especially the capacity to feel with others or to imaginatively put oneself “in their shoes,” the concepts’ sometimes shared, sometimes divergent histories reveal more complicated origins, as well as vexed and ongoing relations to feeling and emotion and to the ethical value of emotional sharing. Though empathy regularly is considered the more advanced and egalitarian of the two, it shares with sympathy a controversial role in historical debates regarding questions of an inborn or divine moral sense, prosocial behavior and the development of human communities, the relation of sensation to unconscious mental processes, brain matter, and neurons, and animal/human difference. In literary criticism, sympathy and empathy have been key components of aesthetic movements such as sentimentalism, realism, and modernism, and of literary techniques like free indirect discourse (FID), which are thought (by some) to enhance readerly intimacy and closeness to novelistic characters and perspectives. Both concepts have also received their fair share of suspicion, as the capacity to feel, or imagine feeling, the emotions of others remains a controversial basis for ethics.
Race and Blackness in Premodern Arabic Literature
Authors: Schine Rachel
Published: October 2021

The signal works of poetry that prominently feature racialized Blackness in early Arabic literature (c. ad 500–1250) include works composed by authors of Afro-Arab heritage as well as by Arab authors who satirized and panegyrized Black subjects. These poets include the pre-Islamic author ʿAntarah ibn Shaddād and the ʿAbbasid-era figures al-Mutanabbī and Ibn al-Rūmī, and thus reflect the shift, across an extensive timeline, from a local, Bedouin poetics to a self-styled cosmopolitan, courtly aesthetic characterized as muḥdath, or modernist. The works are situated not only within the changing conventions of genre, but also within an arc that traces the emergence of new race concepts and racialized social institutions in the transition from the pre-Islamic era to Islam and from the early conquests to ʿAbbasid imperialization. Critical instances of these works’ intertextual movements demonstrate how racial logic accretes in various Arab-Muslim textual traditions, showing how poetry intersects with popular epic as well as high literary geographical, ethnological, and commentarial corpuses. As verse moves across a myriad of later literary forms, its context-specific representations of racial difference are recontextualized and received in ways that contribute to a broader transregional and transtemporal discourse of racialized Blackness.
Latin American Public Administration
Authors: Chudnovsky Mariana
Published: October 2021

The reality of Latin American public administrations has surpassed many of the categories that could be derived theoretically. In fact, a common feature of most public administrations in the region is, precisely, their internal heterogeneity. The alternation of “fashions and models” has left various (and at times contradictory) organizational remnants: accumulated “geological layers” of different instruments (and modes) of management—replaced by other “prettier and better” ones before concluding their cycle; frustrated and/or interrupted reforms that generate daily confusion as a result of the tensions caused between management systems; and half-implemented regulations patched up with new laws that seek to resolve the failures of the previous ones, causing complex regulatory mosaics for the future implementers of the new reforms. The difficulty of professionalizing the civil service in the region is a good indicator of the (continued) absence of consolidated Weberian administrative bureaucracies and a clear expression of the coexistence of different public administration models and development strategies.
Political Culture in Africa
Authors: Nyenhuis Robert , Mattes Robert
Published: October 2021

A useful summary of political culture is a people’s values, knowledge, and evaluations of their political community, political regime, and political institutions, as well as how they see themselves and others as citizens.

Although the current map of Africa was originally drawn by European colonial powers, its states and state boundaries are no longer artificial abstractions. Ordinary Africans have developed a strong identification with their national identities, even as many maintain strong attachments to subnational linguistic, regional, or religious identities. Africans also say they want those states to be governed democratically, though the depth of their commitment to all aspects of democratic governance is not always consistent.

Other aspects of political culture are marked by important contradictions. Even though people can be highly critical of incumbent leaders, they tend to exhibit high and often uncritical levels of trust in government and state institutions. At the same time, they express very low levels of trust in other citizens, or at least in those who do not share common ethnic or local identities. Yet they have high levels of membership in community organizations and are often involved in local politics. And though they express a high level of interest in politics, most Africans exhibit low levels of political efficacy.

But Africa is not a country, and these attitudes often are often very different across the continent. Indeed, in many places, it is far from certain whether citizen support is sufficient to sustain the multiparty systems and democratic rule that emerged in the 1990s.
Civilian Coup Advocacy
Authors: Kinney Drew Holland
Published: October 2021

Available scholarship on civil–military relations, and coup politics in particular, tends to treat military coups d’état as originating purely within the minds of military officers; that is, the overwhelming bulk of scholarship assumes that the idea to seize power stems from officer cliques. To the extent that societal factors (e.g., polarization, economic decline, party factionalism) explain coups, they merely account for why officers decide to seize power. Most research that discusses civilian support for coups does so within single case studies—almost entirely drawn from the Middle East and North Africa. Building on a vibrant wave of studies that disaggregates civil–military institutions, a small body of recent research has begun to systematically and comprehensively consider the theoretical and empirical importance of civilian involvement in military coups. This perspective deemphasizes the military’s possession of weapons and instead focuses on ideational sources of power. Civilians have more power and resources to offer military plotters than existing scholarship has given them credit for. Civilian elites and publics can legitimate coups, organize them, manipulate information on behalf of the plotters, and finance coups for their own economic interests. In short, to fully understand coups, one must seek as much knowledge as possible about their formation, including where the idea for each plot originated. Such detailed analysis of coup plots will give researchers a clearer picture about the motivating factors behind coups.
Telework and Remote Work
Authors: Vartiainen Matti
Published: October 2021

“Telework” and “remote work” have both increased sharply in recent years during and after the pandemic. The basic difference between telework and remote work is that a teleworker uses personal electronic devices in addition to working physically remotely from a place other than an office or company premises, whereas remote work does not require visits to the main workplace or the use of electronic personal devices. “Mobile tele- and remote workers” use several other places in addition to home for working. “Digital online telework” is a global form of employment that uses online platforms to enable individuals, teams, and organizations to access other individuals or organizations to solve problems or to provide services in exchange for payment. Often tele- and remote workers cowork in virtual teams and projects. The prevalence of various types of tele- and remote working vary. Although there are conceptual challenges to operationalizing the concept, it is estimated that hundreds of millions—and possibly more—people today earn their living working at and from their home or other places using digital tools and platforms. In the future, it is expected that new hybrid modes of working will emerge enabled by digital technologies. These changes in working increase the complexity of job demands because of the increased variety of contextual job characteristics. The main benefits of these new ways of working are organizational flexibility and individual autonomy; at the same time, unclear social relations may increase feelings of isolation and challenge the work-life balance.
Race, Ethnicity, and Police–Community Relations
Authors: Peck Jennifer H. , Elligson Richard L.
Published: October 2021

The relationship between race, ethnicity, and police–community relations can be traced through the historical development of the United States. Through the eras of slavery, the Civil Rights movement, and, most recently, the Black Lives Matter movement, police–community relations with racial and ethnic minorities are a complex and complicated area of inquiry. Although research has shown that Blacks hold the most negative perceptions of police, followed by Hispanics and then Whites, understanding race relations between minority citizens and law enforcement is tied to numerous issues. The individual and combined effects of disadvantaged neighborhood characteristics, personal and vicarious experiences with police, and media exposure to high-profile incidents of police–citizen encounters are only a few of the factors that relate to differences in police–community relations across racial/ethnic groups. To mitigate the negative effect of media exposure of high-profile incidents related to police perceptions and behaviors, organizational justice is one component of law enforcement that may offer some perspective.

Additional issues that are correlated with police–community relations for Blacks and Hispanics are greater levels of mistrust between minorities and the police, over- and underenforcement in minority communities, and negative perceptions of police legitimacy and procedural justice held by minorities. Problems surrounding police culture, cynicism, and misconduct (e.g., use of force) are further areas that connect to police–community relations and are more salient for minority residents than for their White counterparts. Practices such as the use of evidence-based policing, invested partnerships between social services and law enforcement, the fair and effective use of authority and force by police, and understanding the specific needs of minority communities may provide promising areas for the enhancement of police–community relations with minorities.
A Political History of Educational Development through International Organizations
Authors: Scott Kamkwamba Olivia
Published: October 2021

International aid to African education is a complicated system involving thousands of organizations and billions of dollars. From global policy provisions to school block construction, the scale of educational development in Africa encompasses a range of solutions unlike those seen in any other region of the world. African classrooms are molded through local, national, regional, and global forces in ways unknown elsewhere. Understanding international aid to African education through a historical lens allows for an informed exploration of theoretical foundations and their impact on today’s realities. A political history emphasizes the oft-times hidden assumptions of aid and development while revealing necessary shifts for future disruption.
Cultural Well-Being in Classroom Communities in Australia
Authors: Emery Sherridan
Published: October 2021

Well-being is an increasingly important topic of schooling policy and research internationally. While the concept of well-being is understood in various ways, little attention has been given to its cultural aspects. The convergence between culture, well-being, and learning is being realized, and the concept of cultural well-being presents new insights relevant to ongoing school reform efforts.

Cultural well-being is a nascent concept in education considered to relate to students’ sense of connection to school, people, places, and cultures. A typology of cultural well-being produced from an Australian study of teachers’ perceptions depicts three prominent interpretations of culture: (a) school culture, (b) processes of recognition, and (c) cultural participation and production. The typology of cultural well-being enables the interrogation of complex power relations, revealing some of the ways that schools continue to reproduce social and cultural inequalities. The application of a typology of cultural well-being illustrates the interplay between school culture, recognition, and cultural participation and can support international initiatives to reform schooling with a greater emphasis on the well-being of all students, potentially addressing and reducing inequalities.
Politics, Policy, and Practice of Teacher Education Reform in India
Authors: Batra Poonam
Published: October 2021

Educational reform measures adopted in India since early liberalization led to systemic changes in the provisioning and practice of school and teacher education. Despite judicial intervention, the state withdrew from the responsibility of developing institutional capacity to prepare teachers, leading to a de facto public policy that undermines the potential role of teachers and their education in achieving equitable, quality education. The policy narrative constructed around quality and knowledge created the logic of marginalizing the teacher, undermining the teacher’s agency and the need for epistemic engagement. Commitment to the Constitution-led policy frame was gradually subverted by a polity committed to privatizing education and a bureaucracy committed to incrementalism and suboptimal solutions to the several challenges of universalizing quality education.

A discourse constructed around teachers, their education, and practice led to narrowing curriculum to a disconnected set of learning outcomes and putting the onus of learning on the child. In the absence of robust institutional monitoring of the Right to Education effort and poor fiscal and teacher provisioning, this act too became a target of neoliberal reform, leading to dilution. The wedge between the constitutional aims of education and market-based reforms has become sharper as the practice of education prioritizes narrow economic self-interest over crucial public and social concerns. This has gradually hollowed out the Constitution-centered national policy perspective on education as critical to the needs of India’s disadvantaged and plural society. A major fallout of this has been the decoupling of concerns for social justice from those for quality education.
Cultural and Linguistic Diversity in School Reform
Authors: Scanlan Martin , López Francesca , Baez-Cruz Maria , Bailey-Jones Tsuru
Published: October 2021

The United States has a rich history of migration, from involuntary immigration resulting from the slave trade to the waves of immigrants who sought a new life on its shores. Partly due to the legislative changes in immigration policy in the last quarter of the 20th century, the cultural and linguistic diversity of the immigrant population has made the country more diverse. These demographic shifts affect schools across sectors in the United States—public and private, secular and religious—and across all geographical settings from urban to suburban to rural. Different immigrant groups have faced prejudice and marginalization, which have cemented cycles of socioeconomic disadvantage and persistent barriers to integration. Immigrant students tend to be disproportionately distributed across schools and are highly concentrated in schools with large numbers of students who are socioeconomically disadvantaged. In tandem, educational policy prioritizes social efficiency (moving immigrant students into the workforce) instead of social mobility (advancing to higher education). The growing knowledge base that is centered on effective approaches to providing equitable opportunities to learn has identified three axes for action: (a) promoting students’ sociocultural integration, (b) cultivating their language proficiency, and (c) supporting their academic achievement. School reforms supporting these axes include the promotion of bilingual education, integration of immigrant students into schools, and advancement of authentic partnerships with families and communities.
Success for All
Authors: Slavin Robert E. , Madden Nancy A.
Published: October 2021

The development, evaluation, and dissemination of Success for All (SFA)—a comprehensive improvement approach for elementary schools—is a story of how developers, coaches, researchers, and practitioners work together to implement this program. There is considerable formal research informing the program and its continual development. However, although there is reliance on rigorous, quantitative research methods in informing model development, there is also a very strong commitment to learn from teacher practice. SFA seeks a constant interplay between teachers’ practice and research. The knowledge SFA coaches bring to the table, many of whom were former SFA teachers, is also integral to the continual development of the model and its implementation strategies.
Roman Libya at the Time of Septimius Severus (193–211 CE)
Authors: Cali Denise
Published: October 2021

The acclamation of the African-born Septimius Severus on April 14, 193 ce, as twenty-first ruler of the Roman Empire, had an enormous impact on the provinces of North Africa and particularly on those territories which nowadays correspond to modern Libya. The emperor’s systematic plan of military consolidation along the border, administrative and fiscal reassessment of minor centers, restoration of social order, and urban renovation of the major cities all resulted in the unprecedented modernization of this part of the Roman provincial system. The Severan period represented the cultural climax of Roman Libya and was a period during which African citizens exerted enormous influence as elected officials at various levels of the imperial administration. Nevertheless, while Libya was for the Greeks a clear geopolitical and cultural entity, in Roman times, despite the reformative actions of Septimius Severus, which targeted first and for the most part Tripolitania and Cyrenaica, the concept of Roman Libya remained a utopia.
Muslim Brotherhoods in West African History
Authors: Nobili Mauro
Published: October 2021

Muslim Sufi brotherhoods (ṭuruq, sing. ṭarīqa) are ubiquitous in contemporary Islamic West Africa. However, they are relative latecomers in the history of the region, making their appearance in the mid-18th century. Yet, Sufism has a longer presence in West Africa that predates the consolidation of ṭuruq. Early evidence of Sufi practices dates to the period between the 11th and the 17th centuries. By that time traces of the Shādhiliyya and the lesser-known Maḥmūdiyya are available between the Atlantic Ocean and Lake Chad, but it was the activities of the Kunta of the Qādiriyya and of al-ḥājj ‘Umar of the Tijāniyya that led to the massive spread of Sufi brotherhoods in the region. The authority of leaders of ṭuruq did not disappear with the imposition of European colonialism. In fact, the power of those leaders who adjusted to the novel political situation further consolidated thanks to their role as mediators between their constituencies and the colonial government. Eventually, the end of the colonial period did not signal the decline of ṭuruq in West Africa. Conversely, during the postcolonial years, Sufi brotherhoods continued flourishing despite the secular nature of West African independent states and the increasing tension with a plethora of equally rising Salafi movements.
Makeba, Miriam
Authors: Jolaosho Omotayo
Published: October 2021

Miriam Makeba (March 4, 1932–November 9, 2008) was among the first to popularize African music on a global scale. Nelson Mandela named her South Africa’s first lady of song; she was also nicknamed Mama Africa. Makeba has been credited with inaugurating the “world music” movement, a designation that she did not like as it marginalized music from a so-called Third World. Already renowned in her native South Africa as a sophisticated and highly sought-after performer in her own right, Makeba’s arrival in the United States in 1959 transformed that country’s music scene. She was a contemporary of Nina Simone and Odetta, with the three women credited for a resurgence of folk music in the United States as they drew songs of everyday life onto the concert stage. South Africa’s apartheid government revoked Makeba’s passport in 1960, when she sought to return home to bury her mother. She was a vocal critic of apartheid in exile, appearing before the United Nations (UN) on at least four occasions (including twice as a delegate of Guinea) to urge sanctions against the apartheid regime and mobilize support for Black South Africans caught under apartheid’s yoke. She supported US civil rights movement organizations and activists, and through her activism embedded US struggles for civil rights within a continuum of African liberation struggles, including anti-apartheid and anti-colonial liberation movements on the continent. She was a cultural ambassador who bore witness to the independence of many African countries through song, with countries for which her performances contributed to the ushering in of independent regimes including Kenya, Tanzania, and Mozambique. She was the only performer at the inaugural conference of the Organization for African Unity. As South Africa’s apartheid government began transitioning power, Makeba was able to return home in 1992 for a brief visit and subsequently decided to permanently return. Under South Africa’s democratically elected regime, Makeba was appointed an FAO (Food and Agriculture Organization) Goodwill ambassador for the UN. She continued performing in her later years, but in November 2008 she collapsed following a performance in Italy and died from cardiac arrest. Her legacy continues through the work of the ZM Makeba Foundation.
Econometrics for Modelling Climate Change
Authors: Castle Jennifer L. , Hendry David F.
Published: October 2021

Shared features of economic and climate time series imply that tools for empirically modeling nonstationary economic outcomes are also appropriate for studying many aspects of observational climate-change data. Greenhouse gas emissions, such as carbon dioxide, nitrous oxide, and methane, are a major cause of climate change as they cumulate in the atmosphere and reradiate the sun’s energy. As these emissions are currently mainly due to economic activity, economic and climate time series have commonalities, including considerable inertia, stochastic trends, and distributional shifts, and hence the same econometric modeling approaches can be applied to analyze both phenomena. Moreover, both disciplines lack complete knowledge of their respective data-generating processes (DGPs), so model search retaining viable theory but allowing for shifting distributions is important. Reliable modeling of both climate and economic-related time series requires finding an unknown DGP (or close approximation thereto) to represent multivariate evolving processes subject to abrupt shifts. Consequently, to ensure that DGP is nested within a much larger set of candidate determinants, model formulations to search over should comprise all potentially relevant variables, their dynamics, indicators for perturbing outliers, shifts, trend breaks, and nonlinear functions, while retaining well-established theoretical insights. Econometric modeling of climate-change data requires a sufficiently general model selection approach to handle all these aspects. Machine learning with multipath block searches commencing from very general specifications, usually with more candidate explanatory variables than observations, to discover well-specified and undominated models of the nonstationary processes under analysis, offers a rigorous route to analyzing such complex data. To do so requires applying appropriate indicator saturation estimators (ISEs), a class that includes impulse indicators for outliers, step indicators for location shifts, multiplicative indicators for parameter changes, and trend indicators for trend breaks. All ISEs entail more candidate variables than observations, often by a large margin when implementing combinations, yet can detect the impacts of shifts and policy interventions to avoid nonconstant parameters in models, as well as improve forecasts. To characterize nonstationary observational data, one must handle all substantively relevant features jointly: A failure to do so leads to nonconstant and mis-specified models and hence incorrect theory evaluation and policy analyses.
Planetary Systems Around White Dwarfs
Authors: Veras Dimitri
Published: October 2021

White dwarf planetary science is a rapidly growing field of research featuring a diverse set of observations and theoretical explorations. Giant planets, minor planets, and debris discs have all been detected orbiting white dwarfs. The innards of broken-up minor planets are measured on an element-by-element basis, providing a unique probe of exoplanetary chemistry. Numerical simulations and analytical investigations trace the violent physical and dynamical history of these systems from astronomical unit (au)-scale distances to the immediate vicinity of the white dwarf, where minor planets are broken down into dust and gas and accrete onto the white dwarf photosphere. Current and upcoming ground-based and space-based instruments are likely to further accelerate the pace of discoveries.
The Irish Border
Authors: Komarova Milena , Hayward Katy
Published: October 2021

The emergence, development, and transformation of the border between Ireland and Northern Ireland reveals much about the changing nature of nation-statehood over the century that followed its creation. In its own way, it is also a subject of innovation. The three interrelated strands of relationships safeguarded by the Good Friday (Belfast) Agreement of 1998 in many ways define the border. These relationships run within and between the two islands of Ireland and Britain, and also between the two political traditions in Northern Ireland. Nationalists and Unionists have come to define much of their ethos in relation to the symbolic meaning of the Irish border: The former want the border removed and the latter see the border as necessary to keep Northern Ireland as part of the United Kingdom. This helps to understand the prominence given to the Irish border in the context of the United Kingdom’s withdrawal from the European Union (EU), as well as the controversy around the terms of the U.K.–EU Withdrawal Agreement, which changed the nature of the relationship between Northern Ireland and the rest of the United Kingdom as well as between Northern Ireland and Ireland. As a consequence of Brexit, the future of borders in and around Ireland—their openness and their governance—will be inevitably shaped by the vicissitudes of the EU–U.K. relationship.
Origins of Food Production in the High Andes
Authors: Langlie BrieAnna S.
Published: October 2021

Vertical topography, high altitude, infertile soils, and an arid climate make the Andes of South America a difficult region for agriculture. Nonetheless, archaeologists have found that potatoes, oca, quinoa, and kañawa were first domesticated by ancient famers in and near a region known as the Altiplano. Research indicates that approximately 6,000 years ago hunter-gatherers began to cultivate wild ancestors of these crops. Shortler thereafter, llama and alpaca herders played an important role in developing crop cultivation strategies; potatoes were uniquely adapted to a mobile pastoral lifestyle. By about 1,500 bce there is archaeological evidence that these crops were fully domesticated and supported early village life. Eventually tubers and chenopods were foundational sustenance for civilization and cities across the pre-Hispanic Andean highlands. Breeding over the last four millennia by generations of Indigenous Andean farmers in the diverse environments and climatic conditions of the Andes has resulted in a hugely diverse array of these crops. The outcome of these efforts is that hundreds of varieties of quinoa and over 5,000 varieties of potatoes are grown by Andean farmers in the 21st century. Potatoes in particular are a unique case of domestication for two reasons: (a) ancient farmers figured out how to store them long term through a freeze-drying process; (b) chemicals that are toxic to humans were not bred out of all varieties; rather, ancient people figured out that eating particular clays made the toxic potatoes less bitter and edible. Through paleoethnobotanical and genetic research, archaeologists have begun to shed light on the tangled history of Andean peoples and their crops.
Elizabeth Seton, American Saint
Authors: O'Donnell Catherine
Published: October 2021

Elizabeth Bayley Seton is the first native-born US citizen to be made a Roman Catholic saint. Canonized in 1975, Seton founded the Sisters of Charity of St. Joseph, the first vowed community of Catholic women religious created in the United States. Seton’s sainthood marked the culmination of a role she first served during her life: a respectable, benevolent face for a church whose local leaders were eager to demonstrate its compatibility with American culture. Seton’s founding of the American Sisters of Charity was a more practical achievement and one that shaped the Catholic Church in the United States in tangible ways. Starting in 1809, when Seton began a school and vowed community in Emmitsburg, Maryland, the Sisters of Charity expanded throughout the United States, eventually running hundreds of schools and orphanages and offering both a spiritual home and a career path for women who chose it. Seton’s life is expressive for what it reveals about her era as well as for her distinctive achievements. Her prominence led to the preservation of decades of correspondence and spiritual writings. Through them it is possible to see with unusual clarity the ways in which the Age of Revolutions and the rise of Napoleon variously disrupted, reinvigorated, and transformed Catholic traditions; to observe the possibilities and constraints Catholicism offered a spiritually ambitious woman; and to witness changes in the relationship between Protestants and Catholics in the United States. Finally, Seton’s rich archive also renders visible one woman’s experience of intellectual inquiry, marriage, widowhood, motherhood, spiritual ambition, and female friendship.
Enslaved and Free Workers and the Growth of the Working Class in Brazil
Authors: Espada Lima Henrique
Published: October 2021

Since the early successful colonial enterprises in Brazil’s territory, men and women forcibly transferred from Africa were used as enslaved workers not only on plantations and other agricultural settings, but also in protoindustrial contexts, such as in the sugar mills and the mining trade and metallurgy. Enslaved people were also a fundamental part of the labor force in the urban artisanry, manufacturing, and the early industrial ventures in the 18th century and after Independence in 1822. In the second half of the 19th century, the first drive of industrialization, in places like Rio de Janeiro, Bahia, and São Paulo, was driven by British investments led by slave-owning entrepreneurs and powered by the intensive use of enslaved labor. Foreign workers brought to the country, Brazilian free manual laborers and other poor immigrants, freed, and enslaved people often worked side by side in shipyards, gunpowder factories, mining endeavors, railways constructions, and many other activities.

In Brazil, especially in urban contexts, many enslaved men and women would rent themselves out, or they would be leased out by their masters, to perform a variety of urban activities, including working in the country’s many artisan shops and industries. In doing so, not only were they able to get financial compensation for their work by becoming ganhadores (enslaved wage earners), but, in that capacity, they also experienced situations usually associated with “free” laborers, such as wage negotiation, bargaining, and even strikes. Some of the enslaved ganhadores were able to buy their own freedom and carried their experiences into their lives as free workers. Therefore, both free and unfree laborers of African descent were present in a variety of trades and enterprises, and the multiplicity of their experiences shaped the dynamics of labor relations, identity building, political and labor cultures, and individual and collective action and organization in the long history of the making of Brazilian working classes.

The heterogeneity that defined the Brazilian laboring classes, composed of people of African descent as well as poor White Portuguese settlers and other immigrants, united and divided by race, gender, nationality, legal status, histories, and cultural backgrounds cannot be stressed enough. It is crucial to understand how the institution of slavery impacted the social and economic relations of all workers, free and unfree, in Brazil even after slavery was abolished in 1888: its legacy of oppression, but also diversity, is expressed in the conflicts and collaborations that marked workers’ collective experience and impacted the transformations that the working classes underwent in post-emancipation Brazil.