the role of symmetry, dimension, and frustration

Recently, the interplay between spin and lattice degrees of freedom has gained a lot of attention due to its importance for various fundamental phenomena as well as for spintronic and magnonic applications. Examples are ultrafast angular momentum transfer between the spin and lattice subsystems during ultrafast demagnetization, frustration driven by structural distortions in transition-metal oxides, or in acoustically driven spin-wave resonances. In this work, we provide a systematic analysis of spin-lattice interactions for ferro- and antiferromagnetic materials and focus on the role of lattice symmetries and dimensions, magnetic order, and the relevance of spin-lattice interactions for angular momentum transfer as well as magnetic frustration. For this purpose, we use a recently developed scheme, which allows an efficient calculation of spin-lattice interaction tensors from first principles. In addition to that, we provide a more accurate and self-consistent scheme to calculate ab initio spin-lattice interactions by using embedded clusters, which allows us to benchmark the performance of the scheme introduced previously

Calculating spin-lattice interactions in ferro- and antiferromagnets: the role of symmetry, dimension and frustration

Recently, the interplay between spin and lattice degrees of freedom has gained a lot of attention due to its importance for various fundamental phenomena as well as for spintronic and magnonic applications. Examples are ultrafast angular momentum transfer between the spin and lattice subsystems during ultrafast demagnetization, frustration driven by structural distortions in transition metal oxides, or in acoustically driven spin-wave resonances. In this work, we provide a systematic analysis of spin-lattice interactions for ferro- and antiferromagnetic materials and focus on the role of lattice symmetries and dimensions, magnetic order, and the relevance of spin-lattice interactions for angular momentum transfer as well as magnetic frustration. For this purpose, we use a recently developed scheme which allows an efficient calculation of spin-lattice interaction tensors from first principles. In addition to that, we provide a more accurate and self consistent scheme to calculate ab initio spin lattice interactions by using embedded clusters which allows to benchmark the performance of the scheme introduced previously

Rotationally invariant formulation of spin-lattice coupling in multi-scale modeling

In the spirit of multi-scale modeling, we develop a theoretical framework for spin-lattice coupling that connects, on the one hand, to ab initio calculations of spin-lattice coupling parameters and, on the other hand, to the magneto-elastic continuum theory. The derived Hamiltonian describes a closed system of spin and lattice degrees of freedom and explicitly conserves the total momentum, angular momentum and energy. Using a new numerical implementation that corrects earlier Suzuki-Trotter decompositions we perform simulations on the basis of the resulting equations of motion to investigate the combined magnetic and mechanical motion of a ferromagnetic nanoparticle, thereby validating our developed method. In addition to the ferromagnetic resonance mode of the spin system we find another low-frequency mechanical response and a rotation of the particle according to the Einstein-de-Haas effect. The framework developed herein will enable the use of multi-scale modeling for investigating and understanding a broad range of magneto-mechanical phenomena from slow to ultrafast time scales

From workplace to home environment: spreading of mouse allergens by laboratory animal workers

PURPOSE Laboratory animal workers (LAW) working with laboratory mice are exposed to mouse allergens (MA). If MA are spread to home environments, this might increase the risk for allergies in LAW and their families. This study aimed to assess 1. whether spreading of MA from workplace to home environment takes place; 2. which factors increase spreading of MA. METHODS In a cross-sectional study, dust samples were taken on the mattress and seating in homes of LAW (n = 105) and an unexposed comparison group (n = 13). From 89 LAW, additional dust samples were taken from their workplaces. Samples were analysed using Mus m1 ELISA kits detection limit (DL) 0.2~ng mus m1/ml. Sociodemographic data, personal history of allergies and cleaning habits, as well as work-related characteristics (LAW only) were assessed by questionnaire. Latent factors were assessed via factor analysis. Tobit models were fitted to analyse the latent factors' contribution to MA spreading. RESULTS MA concentration on the seating was significantly higher in home environments of LAW (median = 1.28~ng mus m1/m2) than in the comparison group (median < DL, p = 0.019). The highest workplace MA concentration was found on the floor of the scullery (median = 140,000.00~ng mus m1/m2), followed by hair-covering caps (median = 76.02~ng mus m1/m2). Cage and mouse facility cleaning tasks and infrequent changing of bed linen at home were statistically significantly associated with higher MA concentrations at home. CONCLUSIONS Spreading of MA from LAW's workplace to their home environment takes place, especially among LAWs involved in cleaning tasks

Data Atlas for Climate-Smart Agriculture in Kenya

Thousands of studies have been published on agricultural innovations in Africa, but those data are generally difficult to access. To make those data accessible, we conducted a systematic review of the impact of more than 100 potential CSA practices on over 50 indicators of productivity, resilience and mitigation in Africa (Rosenstock et al. 2015). The result is a powerful database combining information from more than 1700 studies of CSA in Africa

Neuronal mTORC1 inhibition promotes longevity without suppressing anabolic growth and reproduction in C. elegans.

mTORC1 (mechanistic target of rapamycin complex 1) is a metabolic sensor that promotes growth when nutrients are abundant. Ubiquitous inhibition of mTORC1 extends lifespan in multiple organisms but also disrupts several anabolic processes resulting in stunted growth, slowed development, reduced fertility, and disrupted metabolism. However, it is unclear if these pleotropic effects of mTORC1 inhibition can be uncoupled from longevity. Here, we utilize the auxin-inducible degradation (AID) system to restrict mTORC1 inhibition to C. elegans neurons. We find that neuron-specific degradation of RAGA-1, an upstream activator of mTORC1, or LET-363, the ortholog of mammalian mTOR, is sufficient to extend lifespan in C. elegans. Unlike raga-1 loss of function genetic mutations or somatic AID of RAGA-1, neuronal AID of RAGA-1 robustly extends lifespan without impairing body size, developmental rate, brood size, or neuronal function. Moreover, while degradation of RAGA-1 in all somatic tissues alters the expression of thousands of genes, demonstrating the widespread effects of mTORC1 inhibition, degradation of RAGA-1 in neurons only results in around 200 differentially expressed genes with a specific enrichment in metabolism and stress response. Notably, our work demonstrates that targeting mTORC1 specifically in the nervous system in C. elegans uncouples longevity from growth and reproductive impairments, and that many canonical effects of low mTORC1 activity are not required to promote healthy aging. These data challenge previously held ideas about the mechanisms of mTORC1 lifespan extension and underscore the potential of promoting longevity by neuron-specific mTORC1 modulation

What is the evidence-base for climate-smart agriculture in Kenya? An analysis of what works where powered by Evidence for Resilient Agriculture (ERA)

Agriculture, forestry and fishing drives Kenya’s economy. This sector accounts for 34% of Gross Domestic Product (GDP), generates more than 60% of the national export earnings, and accounts for 40% of the country's total employment (World Bank 2020). Most farmers (between 70 and 80%) are smallholders who produce almost two thirds of the food in the country (FAO 2015). Maize and beans are the cornerstone of agricultural production, covering 37% and 21% of the total cultivated land, respectively. Other major food crops are cowpea, pigeon pea, potatoes, cassava, millet, sweet potato, mango, coconut, banana, rice and cabbage. Major export crops include tea, coffee, cut flowers, avocados, beans and nuts

The business case for resilient agriculture: A financial and risk analysis of maize farming technologies in Kenya

Maize-mixed farming is the most important food production system in East and Southern Africa, stretching over 19% of the cultivated area and engaging approximately 60 million people [1]. In Kenya, maize (Zea mays L.) is the main staple of 96% of the population and is cultivated by more than a third (38%) of the farmers [2]. Roughly 70% of production is small-scale (0.1-2 hectares [ha]) [3]. Maize areas cover approximately 1.8 million ha, from the coast lowlands (1-1250 meters above the sea level [masl]) to high potential highlands (>2100 masl), including eight provinces: Rift Valley (with the largest area under maize), Nyanza, Eastern, Western, Coast, Central, North Eastern, and Nairobi

The business case for resilient agriculture: A financial and risk analysis of maize farming technologies in Malawi

Maize-based farming systems are the most important food production system in East and Southern Africa, stretching over 19% of the cultivated area and engaging approximately 60 million people [1]. In Malawi, maize (Zea mays L.) is the main staple crop. It represents roughly 48% of the population’s dietary energy consumption and occupies 80-85% of the total cultivated land [2]. Almost all farmers cultivate some maize. Maize areas cover all eight Agricultural Development Divisions (ADD), with Lilongwe and Kasungu containing nearly 50% of the country’s area planted to maize

What is the evidence-base for climate-smart agriculture in Malawi? An analysis of what works where powered by Evidence for Resilient Agriculture (ERA)

Agriculture drives Malawi’s economy. This sector accounts for 30% of Gross Domestic Product (GDP), generates more than 80% of the national export earnings and employs 64% of the country's workforce. This productivity results in large part from the actions of smallholder farmers, which generate 70% of the economic agricultural value in the country. Much of this productivity is from maize, which covers about 50% of the total cultivated land in Malawi and is grown by 97% of farmers. Other major food crops include cassava, rice, sorghum, sweet potato, beans, groundnuts and pigeon pea