dd-abelian quotients of (d+2)(d+2)-angulated categories

Let ${\mathscr T}$ be a triangulated category. If $T$ is a cluster tilting object and $I = [ \operatorname{add} T ]$ is the ideal of morphisms factoring through an object of $\operatorname{add} T$, then the quotient category ${\mathscr T} / I$ is abelian. This is an important result of cluster theory, due to Keller-Reiten and K\"{o}nig-Zhu. More general conditions which imply that ${\mathscr T} / I$ is abelian were determined by Grimeland and the first author. Now let ${\mathscr T}$ be a suitable $( d+2 )$-angulated category for an integer $d \geqslant 1$. If $T$ is a cluster tilting object in the sense of Oppermann-Thomas and $I = [ \operatorname{add} T ]$ is the ideal of morphisms factoring through an object of $\operatorname{add} T$, then we show that ${\mathscr T} / I$ is $d$-abelian. The notions of $( d+2 )$-angulated and $d$-abelian categories are due to Geiss-Keller-Oppermann and Jasso. They are higher homological generalisations of triangulated and abelian categories, which are recovered in the special case $d = 1$. We actually show that if $\Gamma = \operatorname{End}_{ \mathscr T }T$ is the endomorphism algebra of $T$, then ${\mathscr T} / I$ is equivalent to a $d$-cluster tilting subcategory of $\operatorname{mod} \Gamma$ in the sense of Iyama; this implies that ${\mathscr T} / I$ is $d$-abelian. Moreover, we show that $\Gamma$ is a $d$-Gorenstein algebra. More general conditions which imply that ${\mathscr T} / I$ is $d$-abelian will also be determined, generalising the triangulated results of Grimeland and the first author.Comment: 19 pages. This is the final accepted version, which has been accepted for publication in the Journal of Algebr

Are Nurses More Altruistic than Real Estate Brokers?

We report results from a dictator game experiment with nurse students and real estate broker students as dictators, and Amnesty International as the recipient. Although brokers contributed substantial amounts, nurses contributed significantly more, on average 76 percent of their endowment. In a second part, subjects chose between a certain repetition of the experiment and a 50-50 chance of costly exit. About one third of the brokers and half of the nurses chose the exit option. While generosity was indeed higher among nurses, even when taking exits into account, the difference cannot readily be attributed to different degrees of altruism.dictator game, exit option, generosity, occupational differences

Dynamic behavior of impurities and native components in model LSM microelectrodes on YSZ

Energy conversion materials exhibit complex dynamic behavior when subjected to elevated temperatures and polarization.</p

The role of gentle algebras in higher homological algebra

We investigate the role of gentle algebras in higher homological algebra. In the first part of the paper, we show that if the module category of a gentle algebra $\Lambda$ contains a $d$-cluster tilting subcategory for some $d \geq 2$, then $\Lambda$ is a radical square zero Nakayama algebra. This gives a complete classification of weakly $d$-representation finite gentle algebras. In the second part, we use a geometric model of the derived category to prove a similar result in the triangulated setup. More precisely, we show that if $\mathcal{D}^b(\operatorname{proj}\Lambda)$ contains a $d$-cluster tilting subcategory that is closed under $[d]$, then $\Lambda$ is derived equivalent to an algebra of Dynkin type $A$. In this case, our approach gives a geometric characterization of all $d$-cluster tilting subcategories of $\mathcal{D}^b(\Lambda)$ that are closed under $[d]$.Comment: 19 pages, comments welcom

Loss of beef during primary production at Swedish farms 2002-2021

Loss of animals is a considerable waste of resources in the meat supply chain, where quantitative data are scarce but critical for guiding improvements. In this study, we used material flow analysis to track the amount of beef diverted away from the food supply chain at the farm level. The beef losses (absolute and as the proportion of yearly initial production) were estimated from data on assisted and unassisted deaths of cattle on Swedish farms obtained from the central register of bovine animals for 2002-2021 combined with official statistics on slaughter weight. The fallen animals were grouped according to age, sex and breed, to enable estimations of the lost amount of carcass weight, both in total and per animal group. The yearly loss during primary production 2017-2021 was on average 13,000 ton carcass weight, or 8.5% of the initial production. No decreasing trend for the loss rate could be determined after 2015, when the Agenda 2030 target 12.3 (Halved food waste and reduced early losses) was introduced. Female dairy breeds showed greater beef losses than dairy males or beef breeds and crossbreeds of both sexes, and their beef losses mostly occurred at 4-5 years of age, thus constituting the hot spot group for lost beef. The results can serve as a base for directed reduction efforts