Structural Constraints Research Articles

A WORKLOAD DEPENDENT RESOURCE CONSTRAINED SCHEDULING PROBLEM FOR NAVY HELICOPTER PILOTS

In this paper, we consider a problem inspired by a real-life problem, which aims to schedule high multiplicity jobs on a single machine by taking into account the organization-specific constraints in a different schedule structure. The schedule is daily with daytime and nighttime periods. The operator is considered as an additional resource that varies in terms of consumption and scheduling depending on the period. There are specific rest periods before and after night-period jobs, and night-period jobs affect both the daily working time and number of the jobs in the daytime- period. In addition, the operator's daily workload is divided into two categories: normal and heavy. If the workload is heavy on consecutive days, specific rest periods must be scheduled. The integer programming model of the problem is presented. The feasible solutions obtained in a short time with greedy constructive heuristic algorithms are used in the exact solution approach as both upper bound and warm-start point. Finally, the effectiveness of the solution approaches is compared and evaluated through numerical experiments carried out for a variety of problem instances of different sizes.

State-led versus market-led: How institutional arrangements impact collaborative governance in participatory urban regeneration in China

Both state-led and market-led institutional arrangements have been experimented in China to form collaborative governance among diverse stakeholders in participatory urban regeneration. Relatively less is known about how institutional arrangements as structural constraints impact the formation of collaborative governance. Building upon Giddens' structuration theory and collaborative governance theory, this paper develops a novel framework that converges on the reciprocity between structural and agency elements and applies it to two residential regeneration cases in Shenzhen. The findings reveal that in residential regeneration, the state-led institutional structure has a greater capacity than the market-led structure to create relational links for community participation. Various factors, including variations in land property rights, path dependencies and institutional certainties, explain the findings. The formation of collaborative governance relies on the shaping effect of structural elements on agents' behaviors in institutional design, including well-designed rules to regulate sanctions, constitute common meaning and premium-allocated resources in accordance with stakeholders’ responsibilities. These findings contribute to a better understanding of collaborative governance and help improve participatory urban regeneration policymaking in China.

Les Métamorphoses D’Apulée 1. Le scénario initiatique archétypal

Apuleius’ Metamorphoses. 1. The Archetypal Initiation Pattern. In this paper I apply a concept I have coined and defined – the anarchetype – to the ancient Greek and Latin novel, more specifically to Apuleius’ Metamorphoses. The text suffers, in my view, from the tension between two contrary formal tendencies, one which is archetypal, another which is anarchetypal. The first structural constraint is the archetypal one. In contrast to the popular narrative Onos, that Apuleius takes as his epic source, The Golden Ass receives a strong organizing pattern, that of an initiation journey. Transformed by mistake, within a sorcery ritual, into an ass, Lucius suffers a series of adventures and encounters with different mystery and philosophical cults (Dea Syria, Dionysos, Isis, Medio-platonism) which bring him back to the human, and then divine condition. This rite of passage offers an archetypal structure to the novel. Keywords: Greek and Latin novel; Apuleius; The Metamorphoses; Mystery Cults; initiation travel; archetype; anarchetype.

Harnessing peer mentorship as a tool to turn human resource for health brain drain into brain gain: a case study of a Nigerian peer-mentored research group

BackgroundPeer mentorship can be a potential tool to reduce the disparities in health research capacity between high- and low- and middle-income countries. This case study describes the potential of peer mentorship to tackle two critical issues: bridging health research capacity of doctors from low- and middle-income countries (LMICs) and the transformation of human resource for health brain drain into "brain gain".Case presentationIn 2021, a virtual peer mentorship group was established by 16 alumni of the University of Benin College of Medical Sciences' 2008 graduating class, residing across three continents. This program aimed to facilitate research collaboration and skill development among colleagues with diverse research experience levels, fostering a supportive environment for career development in research. The group relied heavily on digital technology to carry out its activities due to the different geographical locations of the group members. Led by experienced peer leaders, the group fostered a collaborative learning environment where members leveraged each other's expertise. Within 18 months, we published two research papers in high-impact peer-reviewed global health journals, launched a mixed-methods research study, and conducted training sessions on research design and implementation. Findings from our work were presented at conferences and workshops. However, logistical hurdles, competing priorities, structural constraints, and uneven participation presented challenges.ConclusionThe peer mentorship collaboration has achieved some successes so far, and this model can be emulated by other cohorts of medical professionals across LMICs. Despite the group's success at a micro- or individual level, there remain significant structural barriers to research capacity building in LMICs that can only be addressed at the meso- and macro-levels by institutions and government, respectively. A systems-level approach is required to develop and support research capacity building and foster global research collaboration and effectively turn brain drain into brain gain.

Phage-encoded bismuth bicycles enable instant access to targeted bioactive peptides

Genetically encoded libraries play a crucial role in discovering structurally rigid, high-affinity macrocyclic peptide ligands for therapeutic applications. Bicyclic peptides with metal centres like bismuth were recently developed as a new type of constrained peptide with notable affinity, stability and membrane permeability. This study represents the genetic encoding of peptide-bismuth and peptide-arsenic bicycles in phage display. We introduce bismuth tripotassium dicitrate (gastrodenol) as a water-soluble bismuth(III) reagent for phage library modification and in situ bicyclic peptide preparation, eliminating the need for organic co-solvents. Additionally, we explore arsenic(III) as an alternative thiophilic element that is used analogously to our previously introduced bicyclic peptides with a bismuth core. The modification of phage libraries and peptides with these elements is instantaneous and entirely biocompatible, offering an advantage over conventional alkylation-based methods. In a pilot display screening campaign aimed at identifying ligands for the biotin-binding protein streptavidin, we demonstrate the enrichment of bicyclic peptides with dissociation constants two orders of magnitude lower than those of their linear counterparts, underscoring the impact of structural constraint on binding affinity.

The development of extremely large male genitalia under spatial limitation.

Extensive research in evolutionary biology has focused on the exaggeration of sexual traits; however, the developmental basis of exaggerated sexual traits has only been determined in a few cases. The evolution of exaggerated sexual traits may involve the relaxation of constraints or developmental processes mitigating constraints. Ground beetles in the subgenus Ohomopterus (genus Carabus) have species-specific genitalia that show coevolutionary divergence between the sexes. Here, we examined the morphogenesis of the remarkably enlarged male and female genitalia of Carabus uenoi by X-ray microcomputed tomography. The morphogenetic processes generating the male and female genitalia at the pupal stage were qualitatively similar to those in closely related species with standard genital sizes. Higher growth rates contributed to the exaggeration of both the male and female genital parts of C. uenoi, possibly related to a gene network commonly upregulated in both sexes. Additionally, the length of the copulatory piece (CP), the enlarged male genital part stored in the aedeagus (AD), reached close to that of the AD at the later developmental stages and thereafter decelerated to grow in parallel with the AD, suggesting a structural constraint on the CP by the outer AD. Then, unlike related species, the lengths of the CP and AD increased at eclosion, suggesting a mechanism leading to further elongation of the male genitalia. These observations suggest that a developmental process allows continuous growth of the male genitalia even under the spatial limitation. These results revealed the spatio-temporal dynamics of the development of exaggerated genital structures under structural constraints.

Somali discontinuous coordinate structures with a focus on conjunct hyperbaton in poetry

Abstract Noun phrase coordination in Somali is expressed by the conjunction iyo to create a single coordinate noun phrase. This is well documented. What has not been documented are instances of the conjunction iyo without a conjunct immediately adjacent to one or the other side of it. In this article I consider such cases. Some are discontinous coordinate constructions in which the conjunct following iyo is not present immediately after the conjunction but occurs later, with other words intervening. I suggest two main types of such cases: conjunct hyperbaton and insertion of an adverbial or discourse marker. Another use of iyo, one in which there is no conjunct immediately before the conjunction, and only one immediately following it at the end of a sentence, is also discussed. This is the case of afterthought, and I suggest that these cases occur only at the end of a main clause. The main focus of the article is on conjunct hyperbaton, which I suggest only occurs in poetry. Some implications of this are discussed in the final section with respect to the Coordinate Structure Constraint (Ross, 1967) as well as aesthetics.

Vulmob, a new multidimensional indicator of mobility vulnerability

Mobility enables to find jobs, go to school or meet people. However, long distances, high costs, car dependency and poor accessibility are sources of mobility vulnerabilities. The current rise in fuel prices may have a strong impact on mobility, especially for households that rely heavily on their cars. Moreover, the need to reduce air pollution and greenhouse gases emissions requires the implementation of ambitious environmental policies. It is therefore necessary to identify transport poor households, affected by financial issues, as well as vulnerable households whose mobility would be strongly impacted by changes in individual mobility conditions and would have difficulties to adapt to this situation. To this end, we construct VulMob, a multidimensional indicator made up of thirteen individual factors organized in four dimensions: financial resources and transport affordability, work constraints, heavy car use and accessibility and structural constraints. We apply this indicator to the Grenoble area, in France. Our results show that 9.6% are highly vulnerable, meaning that they face at least six vulnerability issues and 5.5% of the households face transport affordability issues. A typology of five profiles of highly vulnerable households shows that some are financially constrained; others are heavy car users, work at night or face public transport accessibility problems.

“You Always Had to Be Very Careful:” Mapping Civil Leisure Constraints for Collegiate Athletes Engaging in Social Media Activism

Collegiate athletes in the United States increasingly turn to social media to advocate for social change. Drawing from interviews with National Collegiate Athletic Association (NCAA) Division I athletes, the goal of this study was to gain a better understanding of the challenges collegiate athletes face when engaging in social media activism. Combining the theoretical lenses of civil leisure and leisure constraints, five higher-order themes capturing civil leisure constraints were identified. At the intrapersonal level, participants experienced mental stress due to reputational considerations. Participants described intense backlash on social media and interpersonal repercussions as barriers at the interpersonal level. Finally, the participants in this study referred to two structural constraints when it came to civil leisure: institutional vulnerability and control of their social media activities by the athletics department. Theoretical contributions and practical implications are discussed to empower more athletes to utilize their leisure time for activist impact.

Design and experimental evaluation of a novel flow-mode magnetorheological damper without accumulator

Researchers in the field of vibration control have shown increasing interest in magneto-rheological dampers (MRDs) in recent years. Conventional flow-mode MRDs typically employ a gas chamber as an accumulator to accommodate volume changes and promote fluid communication. However, this approach introduces manufacturing complexities and raises production costs. To overcome these challenges, we propose a novel configuration for flow-mode MRDs that replaces the accumulator with a structural constraint. This modification leads to a more compact and cost-effective MRD solution suitable for engineering applications. This paper presents an introduction, followed by the configuration and design of the novel MRD for a case study involving a vehicle suspension system. To enhance output performance, we optimize the significant geometry of the damper using the finite element method (FEM), taking into account the damping force, off-state force, and inductive time constant of the damper. Based on the optimal simulation results, we provide a detailed design of the optimized flow-mode MRD without an accumulator for prototype fabrication. To assess the practical performance of the proposed MRD prototype, we conducted experiments on a test rig and engaged in comprehensive discussions based on the obtained results.

“Making Democracy Safe for the World”: Kenneth Waltz on Realism, Democracy, and War

Abstract This paper reevaluates the history of how some anti-war realists have assessed the relationship between democracy and armed conflict. To do so, I turn to a central realist figure: Kenneth Waltz. Drawing on newly available archival sources and his published work, I explore Waltz’s shifting relationship with American democracy, foreign policymaking, and war. I focus on his career-long anti-war commitments, tracing his foreign policy engagements over the half century of his academic career. Early on, Waltz argued in favor of American democracy as a source of adaptive, effective foreign policy. Gradually, however, his views shifted. After the Cold War and especially after 9/11, his anti-war beliefs and belief in democratic foreign policymaking came increasingly into tension. He moved from defending American democratic foreign policymaking to calling for structural constraints from without. We see this in Waltz’s late-life endorsement of the Iranian nuclear program, which was motivated not just by his well-known optimism about proliferation, but also by the hope that an Iranian nuclear arsenal would deter American intervention in the Middle East. Waltz’s experience has implications both for how we read his body of work and for how we understand realist attempts to shape foreign policy.

The evolution of mammalian Rem2: unraveling the impact of purifying selection and coevolution on protein function, and implications for human disorders.

Rad And Gem-Like GTP-Binding Protein 2 (Rem2), a member of the RGK family of Ras-like GTPases, is implicated in Huntington's disease and Long QT Syndrome and is highly expressed in the brain and endocrine cells. We examine the evolutionary history of Rem2 identified in various mammalian species, focusing on the role of purifying selection and coevolution in shaping its sequence and protein structural constraints. Our analysis of Rem2 sequences across 175 mammalian species found evidence for strong purifying selection in 70% of non-invariant codon sites which is characteristic of essential proteins that play critical roles in biological processes and is consistent with Rem2's role in the regulation of neuronal development and function. We inferred epistatic effects in 50 pairs of codon sites in Rem2, some of which are predicted to have deleterious effects on human health. Additionally, we reconstructed the ancestral evolutionary history of mammalian Rem2 using protein structure prediction of extinct and extant sequences which revealed the dynamics of how substitutions that change the gene sequence of Rem2 can impact protein structure in variable regions while maintaining core functional mechanisms. By understanding the selective pressures, protein- and gene - interactions that have shaped the sequence and structure of the Rem2 protein, we gain a stronger understanding of its biological and functional constraints.

A hierarchical structure in the N-glycosylation process governs the N-glycosylation output: prolonged cultivation induces glycoenzymes expression variations that are reflected in the cellular N-glycome but not in the protein and site-specific glycoprofile of CHO cells.

N-glycosylation is a central component in the modification of secretory proteins. One characteristic of this process is a heterogeneous output. The heterogeneity is the result of both structural constraints of the glycoprotein as well as the composition of the cellular glycosylation machinery. Empirical data addressing correlations between glycosylation output and glycosylation machinery composition are seldom due to the low abundance of glycoenzymes. We assessed how differences in the glycoenzyme expression affected the N-glycosylation output at a cellular as well as at a protein-specific level. Our results showed that cellular N-glycome changes could be correlated with the variation of glycoenzyme expression, whereas at the protein level differential responses to glycoenzymes alterations were observed. We therefore identified a hierarchical structure in the N-glycosylation process: the enzyme levels in this complex pathway determine its capacity (reflected in the N-glycome), while protein-specific parameters determine the glycosite-specificity. What emerges is a highly variable and adaptable protein modification system that represents a hallmark of eukaryotic cells.

Analiza strukturalna i zróżnicowanie pegmatytów w starożytnym twierdzeniu, Giraúl IV, dystrykt pegmatytów Namibe, Angola

Since the early 60´s, in the past XX century, the Giraúl pegmatites have been known for their resources of beryl, mica and feldspars, which were exploited in a regular basis from Giraúl claims I to IV till 1974, during the Portuguese administration of Angolan territory. A broader exploration of this pegmatite field was performed by the ancient Lobito Mining Company (LMC) engaged in detailed geological mapping of the granitic pegmatites and the structural constraints of their location. A structural map of the region was than elaborated, combining the interpretation of aerial photographs with field work performed by the LMC geologists. Recently, a growing economic interest is attributed to these claims, in the region of Bulamucolocai, Pitau and Muvero desert-dry rivers (locally known as “Mulolas”), considering the Li, Cs, and Ta (LCT) metallic specialization of some pegmatite bodies and the occurrence of beryl and tourmaline gemstones, mainly, morganite (Cs-beryl), aquamarine and also elbaite-liddicoatite. Giant crystals of spodumene, up to 6 m in length, define individualized quartz + spodumene units inside some of the more typical LCT pegmatite bodies. Pollucite was identified in the main pegmatites of Giraúl IV claim and not in the adjacent igneous leucocratic breccias. These, in turn, correspond to a complex pegmatite assemblage, very peculiar in what concerns its selective metasomatic effect over some surrounding rocks, with the formation of rims of holmquistite amphibole in contact with gabbro and norite and schorl-dravite tourmaline in contact with gneissic to metapelitic hosts. The breccia-like granitic rock combines clasts of spodumene an K-feldspar with a matrix mainly composed of some quartz, albite and mica including tourmaline, garnet and F-apatite, as accessory minerals. In the same area, huge potassic pegmatites hold giant crystals of microcline and orthoclase and very little quartz, being unusual due to its high content of triplite – zwieselite and triphylite – lithiophilite primary phosphates. The overall composition of these pegmatites is more likely syenitic (low quartz content) than truly granitic. A high-resolution structural analysis of the LCT ensemble (pegmatite plus related lithotypes) is now proposed enhancing the unusual relations between granite breccia plugs, sill-like more typical pegmatites, irregular shaped isodiametric bodies and products of metasomatism. This approach will lead to the understanding of the true dimension, anatomy and inner fraccionation of the different LCT facies and rare-metal deposits with obvious consequences regarding mineral detection and resource – reserve estimation, through the proposal of a more suitable conceptual model to rule its exploration.

Application of a hybrid-driven framework based on sensor optimization placement for the thermal error prediction of the spindle-bearing system

The precise thermal error prediction of spindle-bearing systems (SBSs) necessitates a comprehensive analysis of information gathered from multi-source sensors. However, limited data availability due to structural constraints poses challenges to fully characterize the system state. In this study, we introduce a data-model hybrid-driven framework based on sensor optimization placement for accurate thermal error prediction of SBSs. Firstly, a thermal hypernetwork method is developed to consider uneven temperature distribution and establish a unified information fusion model for state estimation. Secondly, based on an analysis of the rapidity and robustness, robust geodesic distance-based fuzzy c-medoid clustering with a simulated annealing algorithm (RGDFCMSA) is proposed to optimize sensor placement by minimizing the information entropy of the system. Next, uncertain parameters with estimability are selected based on SIAN and Sobol’s sensitivity indicator under optimal sensor placement. Furthermore, a multilayer particle filter (MLPF) is proposed to estimate temperature fields and predict the thermal error of SBSs by fusing information from multiple sources with different fidelity. Finally, experiments under different working conditions are conducted to validate the effectiveness and accuracy of the proposed method. The result indicates that the proposed framework is capable of an accurate estimation of the global temperature field, uncertain thermal parameters and thermal errors.

Children’s Health Lifestyles and the Perpetuation of Inequalities

Health lifestyles are a well-theorized mechanism perpetuating health and social inequalities, but empirical research has not yet documented crucial aspects: (1) health lifestyles’ collective nature or content beyond behaviors and (2) how people choose among available lifestyles in their social contexts. We conducted interviews, observations, and focus groups with families in two middle- to upper-middle-class communities. Contemporary class-privileged parenting involves constructing an individualized health lifestyle reliant on an expansive understanding of health and composed of parents’ identities and narratives, children’s health behaviors and identity expressions, and community norms. Children’s predominant health lifestyles in our sample vary by focus on parent versus child identity expression and on future achievements versus present well-being. Parents expect health lifestyles to influence future socioeconomic attainment and health inequalities. Understanding how health lifestyles encompass more than behaviors and are locally contextualized and how people choose them within structural constraints can inform research and policy.

Struggle, Exit, “Resilience”—or How Precarious Workers Cope with Late Neoliberalism. Individual and Collective Agency of Female Migrant Domestic Workers in Spain

Abstract This article inquires the individual and collective agency of female migrant domestic workers in Spain. I use fieldwork conducted between 2013 and 2023 to examine the interplay between the migrant workers’ individual coping strategies, the claims-making strategies of the domestic workers’ trade union Sindihogar, and the structures they operate within and attempt to challenge. Drawing on contemporary research about precarious workers’ movements, I aim to explore to what extent this social movement union has the potential to reduce the power of structural constraints and increase the power of agency. Implicit is a broader, more provocative question: To what extent is substantial change possible within the current political-economic order, here defined as late neoliberalism? I found that while the movement’s community-building approach may empower activists at an individual level, there are significant structural barriers to its potential to accomplish change in terms of better job conditions for this highly precarious workforce. In addition, I suggest that an increasing focus on precarious workers’ “resilience” risks undermining narratives of structural transformation.

Functional effects of mutations in proteins can be predicted and interpreted by guided selection of sequence covariation information

Predicting the effects of one or more mutations to the in vivo or in vitro properties of a wild-type protein is a major computational challenge, due to the presence of epistasis, that is, of interactions between amino acids in the sequence. We introduce a computationally efficient procedure to build minimal epistatic models to predict mutational effects by combining evolutionary (homologous sequence) and few mutational-scan data. Mutagenesis measurements guide the selection of links in a sparse graphical model, while the parameters on the nodes and the edges are inferred from sequence data. We show, on 10 mutational scans, that our pipeline exhibits performances comparable to state-of-the-art deep networks trained on many more data, while requiring much less parameters and being hence more interpretable. In particular, the identified interactions adapt to the wild-type protein and to the fitness or biochemical property experimentally measured, mostly focus on key functional sites, and are not necessarily related to structural contacts. Therefore, our method is able to extract information relevant for one mutational experiment from homologous sequence data reflecting the multitude of structural and functional constraints acting on proteins throughout evolution.

Professional Women as Perpetrators: A Conversation with Valérie, “Rwanda’s Voice of Death”

ABSTRACT The literature on women’s participation in genocide and related violence focuses on the actions of women who are either at the very top or at the very bottom of social hierarchies. Exceptional roles played by a select few elite women prosecuted at international criminal tribunals have been recognized. Scholars have also examined the motivations of ordinary women who are swayed by ethnocentric scapegoating or commit violence out of fear and coercion, including social and economic incentives. In-depth analyses of female perpetrators in the professionals category who, along with men in that category, serve as bridgemakers between commoners and leaders are scarce. With the exception of nurses, teachers, and secretaries involved in the Holocaust, the professionals category is gravely understudied in scholarship on perpetrators. This article begins to rectify this gap by examining the case of Valérie Bemeriki who, as a journalist for the Radio Télévision Libre des Mille Collines (RTLM), promoted the genocide against the Tutsi in Rwanda. Valérie is a perpetrator who was intimately close to many Rwandans, including her victims, through the radio, yet she is simultaneously unfamiliar as her motivations have not been widely disclosed. The article provides an interpretive analysis of my interview with Valérie, radio transcripts of Valérie’s hate speech obtained by the International Criminal Tribunal for Rwanda (ICTR), and Rwandan and international newspapers and secondary source materials concerning Valérie. The findings suggest that perpetrators in the professionals category convey a contradictory experience in their motivations during the violence and their grievances in the aftermath. While Valérie minimized her agency in the genocidal machine, emphasizing structural constraints, she actively distinguished herself from powerless commoners, including Rwandan women living in a deeply patriarchal society. The article portrays Valérie as a strategic professional who hoped to excel by catering to powerful political figures.

Twin-Tool Orientation Synchronous Smoothing Algorithm of Pinch Milling in Nine-Axis Machine Tools.

Pinch milling is a new technique for slender and long blade machining, which can simultaneously improve the machining quality and efficiency. However, two-cutter orientation planning is a major challenge due to the irregular blade surfaces and the structural constraints of nine-axis machine tools. In this paper, a method of twin-tool smoothing orientation determination is proposed for a thin-walled blade with pinch milling. Considering the processing status of the two cutters and workpiece, the feasible domain of the twin-tool axis vector and its characterization method are defined. At the same time, an evaluation algorithm of global and local optimization is proposed, and a smoothing algorithm is explored within the feasible domain along the two tool paths. Finally, a set of smoothly aligned tool orientations are generated, and the overall smoothness is nearly globally optimized. A preliminary simulation verification of the proposed algorithm is conducted on a turbine blade model and the planning tool orientation is found to be stable, smooth, and well formed, which avoids collision interference and ultimately improves the machining accuracy of the blade with difficult-to-machine materials.