We present a method for narrowing nonparametric bounds on treatment effects by adjusting for potentially large numbers of covariates, using generalized random forests. In many experimental or quasi-experimental studies, outcomes of interest are only observed for subjects who select (or are selected) to engage in the activity generating the outcome. Outcome data are thus endogenously missing for units who do not engage, and random or conditionally random treatment assignment before such choices is insufficient to identify treatment effects. Nonparametric partial identification bounds address endogenous missingness without having to make disputable parametric assumptions. Basic bounding approaches often yield bounds that are wide and minimally informative. Our approach can tighten such bounds while permitting agnosticism about the data-generating process and honest inference. A simulation study and replication exercise demonstrate the benefits.

Arnaldo Tamayo Méndez, the first Cuban, Latin American, and person of African descent to travel to space, has experienced a significant evolution in his persona since his historic flight aboard Soyuz 38 in 1980. This article explores three pivotal phases in this transformation: first, his portrayal in the media as a pioneering Cuban cosmonaut, which positioned him among the socialist elite of the Space Age; second, the controversy regarding the identity of the first Black person in space, which brought renewed attention to Tamayo’s achievements; and third, the ongoing reconfiguration of his image through social-media platforms, allowing for broader engagement with diverse audiences. By applying the principles of persona analysis to a multilinguistic set of historical documents and images related to Tamayo, this study illustrates the malleability of his self-fashioning for different audiences and how it has adapted to reflect changing sociopolitical contexts and the evolving landscape of public representation in the digital age.

This article theorises Indigenous feminist relational freedom that emphasises the ways in which relations and structures of domination disproportionately impact women and gender-diverse people, including through gender-based violence and environmental harm. The theory of relational freedom critiques both one-dimensional conceptions of Indigenous relationality and the conventional framing of Indigenous sovereignty and self-determination through the lens of non-interference, a concept rooted in political autonomy grounded in liberal thought. While non-interference correctly emphasises the need for Indigenous autonomy from state intervention, it falls short in addressing the deeper aspects of Indigenous freedom. Western interference has long impacted Indigenous life, which has led Indigenous self-determination discourses to focus on avoiding state intervention. However, while this emphasis on political autonomy is valid, it does not account for structural forms of domination, particularly underlying inequalities that perpetuate subordination within these structures. These structures range from state institutions that dispossess Indigenous communities to internal systems of gender-based domination that marginalise Indigenous women and LGBTQ+ individuals. The persistence of these structures significantly impedes the full realisation of Indigenous self-determination. The article ultimately theorises Indigenous feminist relational freedom within broader frameworks of feminist relational autonomy and citizenship and Indigenous gift relations, exploring practical approaches for applying the principles of relational freedom within Indigenous governance.

Interfacial interactions, including adhesion and friction, directly affect the ability of the robot system to interact with the external environment, such as the realization of operation and motion functions. Bionics provides guidance for the active control of interface forces. Creatures such as geckos, tree frogs, octopuses, and beetles have developed delicate topological structures and smart control strategies during long-term evolution, facilitating their ability to adhere to, manipulate, capture, and traverse various surfaces across diverse environments. Inspired by the advantages of high strength, adaptability, controllability, durability, and no residue, biomimetic controllable adhesion structures, materials, and systems have been developed, showing a wide range of potential applications in reversible attachment, flexible locomotion, and dexterous grasping. In this paper, the mechanisms and theoretical models of various biological reversible adhesion systems in nature are summarized. Then the design criteria, optimization method, and preparation technology of the artificial adhesion structures based on van der Waals interaction, capillary force, negative pressure, and mechanical interlocking mechanisms are reviewed. In particular, the adhesion/load ratio and the switch ratio of adhesive materials and structures are highlighted to evaluate the adhesion ability and controllability of various designs. The applications of biomimetic controllable adhesion structures and systems in robotics manipulation and locomotion are presented. Finally, the conclusion and possible future direction are discussed.

Drawing on focus groups conducted with musicians based in England, we discuss how musicians with backgrounds in different genres evaluate the effects of a range of music-related digital platforms on musicians and music culture. Alongside criticisms, some of them familiar from recent public debate and academic research, we identify a number of more ambivalent and even positive perspectives on the platformisation of music. We analyse the divided responses of our focus group participants under three main headings: attitudes towards music streaming platforms and record labels; attitudes towards social media and short video platforms, in particular, their use as promotional and branding mechanisms; and attitudes towards the abundance of data available to musicians from these various kinds of digital platforms. In our concluding comments, we consider the possible objection that musicians’ ambivalent and sometimes positive appraisals might represent misguided or mistaken perspectives concerning the effects of platformisation.

This study explores an emerging yet under-researched group within the Chinese bureaucratic system: grassroots female civil servants. Although there is a growing focus in academia on female officials in China, existing research mainly concentrates on the gender representation and career pathways of high-ranking female officials. This research delves into the work and life choices faced by female civil servants in local governments. Despite official discourse advocating for gender equality, interviews with 21 female public servants from a poverty-stricken county in northern China reveal that the demands of local government work and gender norms impose a double burden on them. Although the civil service is known for its stability, these women often have to put in extra effort into demanding and exhausting jobs, frequently sacrificing promotion opportunities to balance family and caregiving responsibilities. However, they seldom express dissatisfaction with this situation, reflecting the entrenched nature of gender role perceptions. This study provides a new explanation for the underrepresentation of female officials at higher levels from a grassroots perspective and reveals the impact of overloaded bureaucratic work on career mobility.

This brief article explores forms for the verb “melt” in Gyalrongic languages, demonstrating that they are cognates and not Tibetan loanwords. Clarification is made on a phonological rule in Japhug, where w- transforms to m- following a nasal, merging the nasal and w-. The article also suggests that the preinitial m- in Mazur Stau and Geshiza is a fossilized autive prefix, possibly resulting from independent changes or language contact. Additionally, Tangut, Bawang, and Puxi Stosde’s usage of a labial medial -w-/-v- for “melt” is hypothesized as an ancient labial causative infix.

Short-form video platforms have reshaped the practices of record companies and music streaming services, giving rise to new cross-audiovisual platform ecosystems. This article adopts the concept of the ‘platform adaptor’ to analyse how music industry practitioners and content producers in China have adjusted their production, distribution, and promotion strategies in response to the affordances of this emerging industrial ecosystem. It discusses the practices of staff who work with musicians to construct ‘hot songs’ (热歌) that can gain popularity across audiovisual platforms and music streaming services. Connecting theoretical ideas about affordance, platform ecologies, and adaptation, this article contributes to research on how cultural forms are ‘optimised’ to be more amenable to the requirements of platforms. The findings demonstrate that emotional encoding has become a pivotal mechanism through which musical commodities gain value as production processes increasingly conform to shareable short-form video formats within the platform economy.

Just before World War I, the Hudson’s Bay Company (HBC) geographically expanded its trade in the Canadian Arctic to derive profits from Arctic fox fur and secure its position in a global value chain (GVC) delivering fur to metropolitan consumers. The “problem of nature” challenged the company’s business venture. Furthermore, “nature” was made and remade by the HBC’s own capital investments. The fox trade itself changed human ecology. Technology transfers to Inuit modified their hunting regimes to increase the company’s returns of polar bear skins. Though these skins had high potential market value, modes of production introduced by the HBC to the Arctic precluded the company from sending high-quality products to metropolitan dressers. Within a changing Arctic human ecology, the HBC produced one highly valued commodity for the market while producing another from which it could derive only modest profit. The HBC’s fox and polar bear trade at the onset of the last century suggests ways that business empires can set off complex and unanticipated changes in human ecologies and, therefore, the dynamics of nature and business at their very peripheries.

This paper presents an effective approach to a compact antenna system incorporating a single artificial magnetic conductor (AMC), designed to operate in the GSM and WiFi frequency bands. The proposed system features a dual-band AMC single element measuring 60 × 60 mm2 with $\pm90^{\circ}$ bandwidths of 100 and 170 MHz. A comprehensive parametric study was conducted to optimize performance and determine the AMC phase while maintaining the compact size of the antenna system. Significant improvements in gain were observed, from −1.61 to 1.88 dBi at 0.9 GHz and from 3.33 to 5.66 dBi at 2.45 GHz. Additionally, the complete system achieves a compact electrical size of 0.18λ0 × 0.18λ0 × 0.048λ0, with an increased front-to-back ratio of 12.3 and 19.9 dB at both frequencies. Finally, measurements of the fabricated prototype show good agreement with the simulation results.