8,916 research outputs found
Learning resilience: Household and institutional responses to multiple livelihood threats in the context of Hurricanes Iota and Eta in northern Nicaragua
Despite converging agendas identifying the importance of farm and livelihood diversification as a key strategy to help reduce disaster risk, conserve biodiversity, reduce climate emissions, improve food security, and build resilience in agriculture and food systems (Kremen and Merenlender 2018; Hufnagel et al., 2020), contentious debates continue about how to accelerate broader food system transformations, who should lead them, and where they are going (e.g., the 2021 UN Food Summit). The influential 2016 report of the International Panel of Experts on Sustainable Food Systems, which analyzed obstacles and opportunities for moving from either traditional subsistence agriculture or industrialized monoculture towards diversified agroecological farming (IPES-Food 2016), helped shift the policy agenda toward an alternative approach to food systems transformation (Gliessman & Ferguson, 2020). However, several assumptions about farmers’ initial starting conditions oversimplified how smallholder farmers begin potential transitions. In practice, many smallholders are neither purely subsistence producers nor entirely specialized commodity farmers; instead they combine subsistence and commercial agriculture to try to make a living, feed themselves, shape their cultures, and achieve their self-defined goals (Burnett & Murphy, 2014). Despite recent studies addressing several of these issues (Kerr et al., 2019), research gaps remain, including the absence of broad-based empirical evidence on which diversification strategies are most likely to contribute to farmers’ dietary diversity, food sovereignty, food security, women’s empowerment, and resilience, and under what circumstances; how smallholders learn about these practices and why they adopt or avoid them; and how cooperatives or other institutions promote (or may retard) them. We seek to fill these gaps using a mixed-methods, place-based study
Sensitisation to Act 2d in patientsallergic to Alternaria alternanta: an epiphenomenom without clinical significance?
In the last few years, the introduction of microarrays in the diagnosis of type I allergy is allowing the clinicians to have a much more accurate picture of their allergenic profile. However, the simultaneous measurement of specific
IgE to multiple molecules can show unexpected sensitisations, without knowing their clinical relevance. For instance, we have been observing a high prevalence
(74%) of sensitisation to Act d 2 (the thaumatin of kiwifruit) in patients sensitised to Alt a 1 (major allergen of Alternaria alternata) with a confirmed allergy to this mould. The aim of the present study was to clarify if there was any clinical relevance in this finding
Niche partitioning of feather mites within a seabird host, Calonectris borealis
According to classic niche theory, species can coexist in heterogeneous environments by reducing interspecific competition via niche partitioning, e.g. trophic or spatial partitioning. However, support for the role of competition on niche partitioning remains controversial. Here, we tested for spatial and trophic partitioning in feather mites, a diverse and abundant group of arthropods. We focused on the two dominant mite species, Microspalax brevipes and Zachvatkinia ovata, inhabiting flight feathers of the Cory's shearwater, Calonectris borealis. We performed mite counts across and within primary and tail feathers on free-living shearwaters breeding on an oceanic island (Gran Canaria, Canary Islands). We then investigated trophic relationships between the two mite species and the host using stable isotope analyses of carbon and nitrogen on mite tissues and potential host food sources. The distribution of the two mite species showed clear spatial segregation among feathers; M. brevipes showed high preference for the central wing primary feathers, whereas Z. ovata was restricted to the two outermost primaries. Morphological differences between M. brevipes and Z. ovata support an adaptive basis for the spatial segregation of the two mite species. However, the two mites overlap in some central primaries and statistical modeling showed that Z. ovata tends to outcompete M. brevipes. Isotopic analyses indicated similar isotopic values for the two mite species and a strong correlation in carbon signatures between mites inhabiting the same individual host suggesting that diet is mainly based on shared host-associated resources. Among the four candidate tissues examined (blood, feather remains, skin remains and preen gland oil), we conclude that the diet is most likely dominated by preen gland oil, while the contribution of exogenous material to mite diets is less marked. Our results indicate that ongoing competition for space and resources plays a central role in structuring feather mite communities. They also illustrate that symbiotic infracommunities are excellent model systems to study trophic ecology, and can improve our understanding of mechanisms of niche differentiation and species coexistence
Star Formation Under the Outflow: The Discovery of a Non-Thermal Jet from OMC-2 FIR 3 and its Relationship to the Deeply Embedded FIR 4 Protostar
We carried out multiwavelength (0.7-5 cm), multiepoch (1994-2015) Very Large
Array (VLA) observations toward the region enclosing the bright far-IR sources
FIR 3 (HOPS 370) and FIR 4 (HOPS 108) in OMC-2. We report the detection of 10
radio sources, seven of them identified as young stellar objects. We image a
well-collimated radio jet with a thermal free-free core (VLA 11) associated
with the Class I intermediate-mass protostar HOPS 370. The jet presents several
knots (VLA 12N, 12C, 12S) of non-thermal radio emission (likely synchrotron
from shock-accelerated relativistic electrons) at distances of ~7,500-12,500 au
from the protostar, in a region where other shock tracers have been previously
identified. These knots are moving away from the HOPS 370 protostar at ~ 100
km/s. The Class 0 protostar HOPS 108, which itself is detected as an
independent, kinematically decoupled radio source, falls in the path of these
non-thermal radio knots. These results favor the previously proposed scenario
where the formation of HOPS 108 has been triggered by the impact of the HOPS
370 outflow with a dense clump. However, HOPS 108 presents a large proper
motion velocity of ~ 30 km/s, similar to that of other runaway stars in Orion,
whose origin would be puzzling within this scenario. Alternatively, an apparent
proper motion could result because of changes in the position of the centroid
of the source due to blending with nearby extended emission, variations in the
source shape, and /or opacity effects.Comment: 16 pages, 4 figures, accepted for publication in The Astrophysical
Journa
Infrared spectral fingerprint of neutral and charged endo- and exohedral metallofullerenes
Small metal-containing molecules have been detected and recognized as one of
the hybrid species efficiently formed in space; especially in the circumstellar
envelopes of evolved stars. It has been predicted also that more complex hybrid
species like those formed by metals and fullerenes (metallofullerenes) could be
present in such circumstellar environments. Recently, quantum-chemical
simulations of metallofullerenes have shown that they are potential emitters
contributing to the observed mid-IR spectra in the fullerene-rich circumstellar
environments of different types of evolved stars. Here we present the
individual simulated mid-IR (~5-50 um) spectra of twenty-eight metallofullerene
species; both neutral and charged endo- and exohedral metallofullerenes for
seven different metals (Li, Na, K, Ca, Mg, Ti, and Fe) have been considered.
The changes induced by the metal-C60 interaction on the intensity and position
of the spectral features are highlighted using charge density difference maps
and electron density partitioning. Our calculations identify the fundamental IR
spectral regions where, depending on the metal binding nature, there should be
a major spectral contribution from each of the metallofullerenes. The
metallofullerenes IR spectra are made publicly available to the astronomical
community, especially James Webb Space Telescope users, for comparisons that
could eventually lead to the detection of these species in space.Comment: Accepted for publication in The Astrophysical Journal Supplement
Series on 19 September 2023 (in press) (13 pages, 7 figures, and 1 table
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