Although episodic volunteering is a popular form of volunteering and has received increasing attention from researchers, the motives and characteristics of episodic volunteers in different industries or types of events remain underresearched, especially in the context of cultural events. This study is based on a sample of more than 2000 episodic volunteers and analyzes demographic characteristics, motives, and volunteer experience of cultural event volunteers by applying between and within analysis. The between analysis compares cultural and social event volunteers and finds that cultural event volunteers show higher time engagement but are more self-serving in their motives. The within analysis emphasizes intrinsic motives over extrinsic motives, leading to the conclusion that saturation of extrinsic motives reduces willingness for future engagements.

In this introductory article to the thematic issue, our aim is to discuss the state of the art in research on co-production of public services. We define co-production, for the purpose of this article rather narrowly, as the involvement of individual citizens and groups in public service delivery. We discuss the concept along three main research lines that emerge from the literature: what are the motives for co-production? How can co-production be organized effectively? What are the effects of co-production? Secondly, we also critically assess the state of the art and discuss some conceptual and methodological issues that are still open to debate. Thirdly, we propose some directions for future research: greater methodological diversity and the need for empirical and comparative research with a specific attention for theoretical advancement in co-production research.

Although episodic volunteers are a critical resource for many organisations, their motives for volunteering are poorly understood. A systematic review was conducted to describe empirical evidence about motives for episodic volunteering (EV) across sectors (sport, tourism, events, health and social welfare). Identified EV motives were then categorised using core functions from the Volunteer Functions Inventory (VFI) for comparison across studies. Twelve databases (1990–December 2014) were searched. Thirty-three English language studies included results describing EV motives. Studies were predominantly cross-sectional, quantitative, event-based and originating in North America. Measurement of motives was also inconsistent. Common motives were helping others and socialising. Physical challenge and healing motives were specific to sport-based events and charity sport events, respectively. Over 80 % of motives were classified using VFI functions, particularly enhancement, values and social functions. The VFI supplemented by qualitative work may be efficacious to further identify EV motives and retention strategies.

Following the literature that focuses on the psychosocial, cognitive and economic motivations for volunteerism, this article presents a phenomenological study of voluntary participation in a community-based waste management initiative involving a total of 24 participants. In line with phenomenology’s accent on uncovering cognitive meanings and essential structures, data were collected by means of 12 individually semi-structured interviews and two focus group discussions. Common cognitive meaning units were identified, guiding an understanding of the essence and structure underlying the volunteer experience, beyond the focus on motives, functions and intentions of volunteer work, yielding insight into the unintended effects of volunteer action on the volunteers themselves and on the community they serve. The data were critically reviewed as a means of understanding the hidden dimensions of volunteerism as they seem to relate to individual and social agency and social transformation and the inherent challenges that such change can effect. From our analysis it appears that it would be valuable to conduct further detailed and larger studies examining the agentic nature of volunteerism in low-to middle-income contexts.

We extend the notion of the J-invariant to arbitrary semisimple linear algebraic groups and provide complete decompositions for the normed Chow motives of all generically quasi-split twisted flag varieties. Besides, we establish some combinatorial patterns for normed Chow groups and motives and provide some explicit formulae for values of the J-invariant.

We prove the geometric Satake equivalence for mixed Tate motives over the integral motivic cohomology spectrum. This refines previous versions of the geometric Satake equivalence for split reductive groups. Our new geometric results include Whitney–Tate stratifications of Beilinson–Drinfeld Grassmannians and cellular decompositions of semi-infinite orbits. With future global applications in mind, we also achieve an equivalence relative to a power of the affine line. Finally, we use our equivalence to give Tannakian constructions of Deligne’s modification of the dual group and a modified form of Vinberg’s monoid over the integers.

We prove cohomological vanishing criteria for the Ceresa cycle of a curve C embedded in its Jacobian J: (A) if $\mathrm{H}^3(J)^{\mathrm{Aut}(C)} = 0$, then the Ceresa cycle is torsion modulo rational equivalence; (B) if $\mathrm{H}^0(J, \Omega_J^3)^{\mathrm{Aut}(C)} = 0$, then the Ceresa cycle is torsion modulo algebraic equivalence, with criterion (B) conditional on the Hodge conjecture. We then use these criteria to study the simplest family of curves where (B) holds but (A) does not, namely the family of Picard curves $C \colon y^3 = x^4 + ax^2 + bx + c$. Criterion (B) and work of Schoen combine to show that the Ceresa cycle of a Picard curve is torsion in the Griffiths group. We furthermore determine exactly when it is torsion in the Chow group. As a byproduct, we deduce that there exist one-parameter families of plane quartic curves with torsion Ceresa Chow class; that the torsion locus in $\mathcal{M}_3$ of the Ceresa Chow class contains infinitely many components; and that the order of a torsion Ceresa Chow class of a Picard curve over a number field K is bounded, with the bound depending only on $[K\colon \mathbb{Q}]$. Finally, we determine which automorphism group strata are contained in the vanishing locus of the universal Ceresa cycle over $\mathcal{M}_3$.

A real variety whose real locus achieves the Smith–Thom equality is called maximal. This paper introduces new constructions of maximal real varieties, by using moduli spaces of geometric objects. We establish the maximality of the following real varieties:

• – moduli spaces of stable vector bundles of coprime rank and degree over a maximal real curve (recovering Brugallé–Schaffhauser’s theorem with a short new proof), which extends to moduli spaces of parabolic vector bundles;

• – moduli spaces of stable Higgs bundles of coprime rank and degree over a maximal real curve, providing maximal hyper-Kähler manifolds in every even dimension;

• – if a real variety has maximal Hilbert square, then the variety and its Hilbert cube are maximal, which happens for all maximal real cubic 3-folds, but never for maximal real cubic 4-folds;

• – punctual Hilbert schemes on a maximal real surface with vanishing first $\mathbb {F}_2$-Betti number and connected real locus, such as $\mathbb {R}$-rational maximal real surfaces and some generalized Dolgachev surfaces;

• – moduli spaces of stable sheaves on an $\mathbb {R}$-rational maximal Poisson surface (e.g. the real projective plane).

This study clarifies the types of motives that are important as a source of cooperation in a linear public goods experiment. Our experimental design separates contributions into those due to confusion, one-shot motives (which includes altruism, warm-glow, inequality aversion, and conditional cooperation), and multi-round motives (which includes a strategic motive under incomplete information, a failure of backward induction, and reciprocity). The experiment reveals that multi-round motives plays an important role in driving cooperative behavior. Confusion and one-shot motives play a minor role.