Richness, composition and trophic niche of stingless bee assemblages in urban forest remnants

Few studies directly address the consequences of habitat fragmentation for pollinating insect communities, particularly for the neotropical key pollinator group of stingless bees. Most studies on bees have defined habitat fragments as remnant patches of floral hosts or forests, overlooking the nesting needs of bees. Their conclusion is that habitat fragmentation is broadly deleterious; however, there are contrasting results in the literature. Insightful studies on habitat fragmentation and bees should consider fragmentation, alteration and loss of nesting habitats—not just patches of forage plants –, as well as the permeability of the surrounding matrix to interpatch movement. Here we investigated the effects of fragmentation caused by urbanization on stingless bee species’ composition and richness, as well as the permeability of the surrounding matrix. We collected bees from flowering plants and recorded phytosociological variables of five forest remnants (ranging from 64 ha to 900 ha) in southeastern Brazil. Large fragments did not contain more species per unit area than smaller ones; in fact, we found more species in small fragments, most of which were generalist bees. The presence of more habitat generalist stingless bee species was also correlated to the structure of vegetation in these fragments. In conclusion, the quality of the habitat within a fragment (structure of vegetation) as well as the quality of the matrix has a direct relation to the bee species composition. This can be seen in the direct relationship between structural diversity of the environment and age of the fragments. The matrix that holds the most recent fragments, probably due to the sprawl of the city, is more heterogeneous than the one with the oldest fragments. The most heterogeneous matrices have a certain balance between the trees, buildings and bare soil or herbaceous vegetation coverage, making the array less impermeable to bees.     

Happiness Inequality: How Much is Reasonable?

We compute the Gini indexes for income, happiness and various simulated utility levels. Due to decreasing marginal utility of income, happiness inequality should be lower than income inequality. We find that happiness inequality is about half that of income inequality. To compute the utility levels we need to assume values for a key parameter that can be interpreted as a measure of relative risk aversion. If this coefficient is above one, as many economists believe, then a large part of happiness inequality is not related to pecuniary dimensions of life.     

An Estimation of the Economic Impact of Migrant Access on GDP: the Case of the Madrid Region

In recent years, the Madrid Region (Comunidad de Madrid) has experienced a huge increase in immigrants accessing the labour market. In this paper, a dynamic input‐output exercise is presented, yielding the direct and indirect effects of this migration inflow on the Madrid GDP. In addition, the induced demand effect is estimated, offering a complete estimate framework of the impact of migrant access on regional value added.     

Strong boundary control,weak boundary control and tailor-made solutions: the role of household governance structures in work–family time allocation and mismatch

To date, the gaps between actual and preferred working hours are mostly theorised and analysed at the individual level. This article provides new insights as to what extent different household arrangements relate to matches or mismatches concerning the achievement of a desired time allocation. The concept of household governance refers to regulations and practices families apply to keep work–family relationships under control, like the earner model, outsourcing of household task and household rules. This article explores by linear regression analyses how these are related to time-use problems of families: the gap between actual and preferred working hours, lack of free time and the experience of time pressure. The rivalling perspectives of flexibility, regulation and boundary theory have different predictions as to which modes of governance produce favourable outcomes. The results generally support boundary theory. However, households often are unable to choose their earner model optimally.     

Avoiding the valley of death in educating strategists

Billions of dollars and hundreds of millions of hours are invested every year in executive education. However, much of this investment dies in a familiar “Valley of Death” (VoD) wherein what is learned in the classroom is not applied when the strategist returns back to work. Based on 30 in-depth interviews and live observation, we investigate the architecture of an executive education program designed to avoid the VoD. In the observed program, senior partners of a strategy consulting firm, and their key strategist clients, are brought together to co-learn strategy associated with scenario planning, and, at the same time, improve their ongoing business relations. We find that adopting a “paired learning structure” and utilizing “live case content” results in “group-level co-learning” (or the co-production of knowledge) that, participants report, avoids the VoD. This research contributes to the scholarship on learning architecture in executive education by establishing linkages to the literature on client-partner relationships, modelling the student, and service co-production in knowledge-intensive organizations, and, in the end, provides a blueprint that professional service firms and business schools, seeking to produce more value for their participants, can jointly emulate.     

Algebraic and combinatorial properties of ideals and algebras of uniform clutters of TDI systems

Let \(\mathcal{C}\) be a uniform clutter and let A be the incidence matrix of \(\mathcal{C}\). We denote the column vectors of A by v ₁,…,v _q . Under certain conditions we prove that \(\mathcal{C}\) is vertex critical. If \(\mathcal{C}\) satisfies the max-flow min-cut property, we prove that A diagonalizes over ? to an identity matrix and that v ₁,…,v _q form a Hilbert basis. We also prove that if \(\mathcal{C}\) has a perfect matching such that \(\mathcal{C}\) has the packing property and its vertex covering number is equal to 2, then A diagonalizes over ? to an identity matrix. If A is a balanced matrix we prove that any regular triangulation of the cone generated by v ₁,…,v _q is unimodular. Some examples are presented to show that our results only hold for uniform clutters. These results are closely related to certain algebraic properties, such as the normality or torsion-freeness, of blowup algebras of edge ideals and to finitely generated abelian groups. They are also related to the theory of Gröbner bases of toric ideals and to Ehrhart rings.