356 research outputs found
Antichiral and nematicity-wave superconductivity
Larkin-Ovchinnikov superconducting state has spontaneous modulation of Cooper
pair density, while Fulde-Ferrell state has a spontaneous modulation in the
phase of the order parameter. We report that a quasi-two-dimensional Dirac
metal, under certain conditions has principally different inhomogeneous
superconducting states that by contrast have spontaneous modulation in a
submanifold of a multiple-symmetries-breaking order parameter. The first state
we find can be viewed as a nematic superconductor where the nematicity vector
spontaneously breaks rotational and translational symmetries due to spatial
modulation. The other demonstrated state is a chiral superconductor with
spontaneously broken time-reversal and translational symmetries. It is
characterized by an order parameter, which forms a lattice pattern of
alternating chiralities.Comment: Version published in Physical Review B Rapid Communication
Convergent biochemical pathways for xanthine alkaloid production in plants evolved from ancestral enzymes with different catalytic properties
Convergent evolution is widespread but the extent to which common ancestral conditions are necessary to facilitate the independent acquisition of similar traits remains unclear. In order to better understand how ancestral biosynthetic catalytic capabilities might lead to convergent evolution of similar modern-day biochemical pathways, we resurrected ancient enzymes of the caffeine synthase (CS) methyltransferases that are responsible for theobromine and caffeine production in flowering plants. Ancestral CS enzymes of Theobroma, Paullinia, and Camellia exhibited similar substrate preferences but these resulted in the formation of different sets of products. From these ancestral enzymes, descendants with similar substrate preference and product formation independently evolved after gene duplication events in Theobroma and Paullinia. Thus, it appears that the convergent modern-day pathways likely originated from ancestral pathways with different inferred flux. Subsequently, the modern-day enzymes originated independently via gene duplication and their convergent catalytic characteristics evolved to partition the multiple ancestral activities by different mutations that occurred in homologous regions of the ancestral proteins. These results show that even when modern-day pathways and recruited genes are similar, the antecedent conditions may be distinctive such that different evolutionary steps are required to generate convergence
Magnetic signatures of domain walls in s+is and s+id superconductors: Observability and what that can tell us about the superconducting order parameter
One of the defining features of spontaneously broken time-reversal symmetry (BTRS) is the existence of domain walls, the detection of which would be strong evidence for such systems. There is keen interest in BTRS currently, in part, due to recent muon spin rotation experiments, which have pointed towards Ba1−xKxFe2As2 exhibiting a remarkable case of s-wave superconductivity with spontaneously broken time-reversal symmetry. A key question, however, is how to differentiate between the different theoretical models which describe such a state. Two particularly popular choices of model are s+is and s+id superconducting states. In this paper, we obtain solutions for domain walls in s+is and s+id systems, including the effects of lattice anisotropies. We show that, in general, both models exhibit spontaneous magnetic fields that extend along the entire length of the domain wall. We demonstrate the qualitative difference between the magnetic signatures of s+is and s+id domain walls and propose a procedure to extract the superconducting pairing symmetry from the magnetic-field response of domain walls
Productive Pinning: A Quantitative Content Analysis Determining the Use of Pinterest by Agricultural Businesses and Organizations
In recent years social media sites have experienced rapid growth among users, specifically the image-based site Pinterest. The purpose of this study was to investigate how agricultural producers and businesses were using Pinterest. A sample of 428 Pinterest users were evaluated using a quantitative content analysis to determine basic information about how Pinterest was used and the presence of four possession rituals: personalizing, claiming, sharing, and storing and hoarding. The research objectives of this study included (1) determining the number of businesses and organizations using Pinterest, (2) identifying what possession rituals are most prominently utilized by agribusinesses and agricultural organizations on Pinterest, and (3) determining what segment of the agricultural industry is represented on Pinterest the most. The results indicated agricultural producers and businesses are utilizing Pinterest but progress is still warranted. More specif ically, the results revealed agriculture’s use of Pinterest is highly personalized, with the most room for improvement being in the area of sharing content agriculturists generate themselves
Ring solitons and soliton sacks in imbalanced fermionic systems
We show that in superfluids with fermionic imbalance and uniform ground state, there are stable solitons. These solutions are formed of radial density modulations resulting in nodal rings. We demonstrate that these solitons exhibit nontrivial soliton-soliton and soliton-vortex interactions and can form complicated bound states in the form of “soliton sacks.” In a phase-modulating (Fulde-Ferrell) background, we find different solitonic states, in the form of stable vortex-antivortex pairs
The whole and its parts : why and how to disentangle plant communities and synusiae in vegetation classification
Most plant communities consist of different structural and ecological subsets, ranging from cryptogams to different tree layers. The completeness and approach with which these subsets are sampled have implications for vegetation classification. Non‐vascular plants are often omitted or sometimes treated separately, referring to their assemblages as “synusiae” (e.g. epiphytes on bark, saxicolous species on rocks). The distinction of complete plant communities (phytocoenoses or holocoenoses) from their parts (synusiae or merocoenoses) is crucial to avoid logical problems and inconsistencies of the resulting classification systems. We here describe theoretical differences between the phytocoenosis as a whole and its parts, and outline consequences of this distinction for practise and terminology in vegetation classification. To implement a clearer separation, we call for modifications of the International Code of Phytosociological Nomenclature and the EuroVegChecklist. We believe that these steps will make vegetation classification systems better applicable and raise the recognition of the importance of non‐vascular plants in the vegetation as well as their interplay with vascular plants
Factors influencing epiphytic bryophyte and lichen species richness at different spatial scales in managed temperate forests
The effect of management related factors on species richness of epiphytic
bryophytes and lichens was studied in managed deciduous-coniferous mixed
forests in Western-Hungary. At the stand level, the potential explanatory
variables were tree species composition, stand structure, microclimate and
light conditions, landscape and historical variables; while at tree level host
tree species, tree size and light were studied. Species richness of the two
epiphyte groups was positively correlated. Both for lichen and bryophyte plot
level richness, the composition and diversity of tree species and the abundance of shrub layer were the most influential positive factors. Besides, for
bryophytes the presence of large trees, while for lichens amount and
heterogeneity of light were important. Tree level richness was mainly
determined by host tree species for both groups. For bryophytes oaks, while for lichens oaks and hornbeam turned out the most favourable hosts. Tree size
generally increased tree level species richness, except on pine for bryophytes
and on hornbeam for lichens.
The key variables for epiphytic diversity of the region were directly
influenced by recent forest management; historical and landscape variables
were not influential. Forest management oriented to the conservation of
epiphyte s should focus on: (i) the maintenance of tree species diversity in
mixed stands; (ii) increment the proportion of deciduous trees (mainly oaks);
(iii) conserving large trees within the stands; (iv) providing the presence of
shrub and regeneration layer; (v) creating heterogeneous light conditions. For
these purposes tree selection and selective cutting management seem more
appropriate than shelterwood system
Identification and Characterization of RcMADS1, an AGL24 Ortholog from the Holoparasitic Plant Rafflesia cantleyi Solms-Laubach (Rafflesiaceae)
10.1371/journal.pone.0067243PLoS ONE86-POLN
- …