624 research outputs found
A microscopic model for spiral ordering along (110) on the MnSi lattice
We study an extended Heisenberg model on the MnSi lattice. In the cubic B20
crystal structure of MnSi, Mn atoms form lattices of of corner-shared
equilateral triangles. We find an ubiquitous spiral ordering along (110) for J1
0, where J1, J2, and J3 are 1st, 2nd and 3rd nearest neighbor
Heisenberg interactions, respectively. While the ordering direction of (110) is
reasonably robust to the presence of the Dzyaloshinskii-Moriya interaction, it
can be shifted to the (111) direction with the introduction of a magnetic
anisotropy term for small J2/|J1|. We discuss the possible relevance of these
results to the partially ordered state recently reported in MnSi.Comment: 5 pages, 4 figure
New Lncs to mesendoderm specification.
Mammalian genomes are pervasively transcribed generating thousands of long noncoding RNAs (lncRNAs) with emergent regulatory roles. Many of these lncRNAs exhibit highly specialised expression patterns during development and typically flank and regulate key developmental factors. In this review, we discuss and summarise the latest advances in our understanding of the roles of lncRNAs during mesendoderm (ME) specification, a key step during gastrulation and the formation of the primitive streak (PS)
Spatial pattern of landslides in Swiss Rhone valley
The present study analyses the spatial pattern of quaternary gravitational
slope deformations (GSD) and historical/present-day instabilities
(HPI) inventoried in the Swiss Rhone Valley. The main objective is
to test if these events are clustered (spatial attraction) or randomly
distributed (spatial independency). Moreover, analogies with the
cluster behaviour of earthquakes inventoried in the same area were
examined. The Ripley's K-function was applied to measure and test
for randomness. This indicator allows describing the spatial pattern
of a point process at increasing distance values. To account for
the non-constant intensity of the geological phenomena, a modification
of the K-function for inhomogeneous point processes was adopted.
The specific goal is to explore the spatial attraction (i.e. cluster
behaviour) among landslide events and between gravitational slope
deformations and earthquakes. To discover if the two classes of instabilities
(GSD and HPI) are spatially independently distributed, the cross
K-function was computed. The results show that all the geological
events under study are spatially clustered at a well-defined distance
range. GSD and HPI show a similar pattern distribution with clusters
in the range 0.75?9 km. The cross K-function reveals an attraction
between the two classes of instabilities in the range 0?4 km confirming
that HPI are more prone to occur within large-scale slope deformations.
The K-function computed for GSD and earthquakes indicates that both
present a cluster tendency in the range 0?10 km, suggesting that
earthquakes could represent a potential predisposing factor which
could influence the GSD distribution
Discovery and functional characterization of cardiovascular long noncoding RNAs
Recent advances in sequencing and genomic technologies have resulted in the discovery of thousands of previously unannotated long noncoding RNAs (lncRNAs). However, their function in the cardiovascular system remains elusive. Here we review and discuss considerations for cardiovascular lncRNA discovery, annotation and functional characterization. Although we primarily focus on the heart, the proposed pipeline should foster functional and mechanistic exploration of these transcripts in various cardiovascular pathologies. Moreover, these insights could ultimately lead to novel therapeutic approaches targeting lncRNAs for the amelioration of cardiovascular diseases including heart failure
Exploring high temperature magnetic order in CeTi_1-xSc_xGe
Most of magnetic transitions related to Ce ordering are found below
T_ord~12K. Among the few cases exceeding that temperature, two types of
behaviors can be distinguished. One of them is related to the rare cases of Ce
binary compounds formed in BCC structures, with a quartet ground state, whose
degeneracy is reduced by undergoing different types of transitions mostly
structural. The other group shows evidences of itinerant character with the
outstanding example of CeRh_3B_2 showing the highest T_ord=115K. The second
highest ordering temperature has been reported for CeScGe with T_ord=47K, but
the nature of this magnetic state has not been investigated very deeply. In
order to shed more light into this unusual high temperature ordering we studied
the structural, magnetic, transport and thermal properties of CeTi_1-xSc_xGe
alloys in the stability range of the CeScSi-type structure 0.25<x<1 This system
presents a rich variety of magnetic behaviors along this concentration range,
with the magnetic ordering growing from ferromagnetic (FM) T_C~7K up to an
antiferromagnetic (AFM) transition at T_N=47K. The different regions show the
following characteristics: i) on the Ti rich side (0.25<x<0.50) it exhibits a
FM ground state (GS) with large saturation magnetization values M_sat up to
~1.15 mu_B. ii) Around x=0.60, the first crystal electric field excited doublet
starts to contribute to the GS magnetic properties. Furthermore an AFM
component with a connected metamagnetic transition appears. iii) At x=0.65 a
clear change in the GS nature is associated to a critical point above which the
GS properties can be described like for an itinerant system (with decreasing
M_sat) and an effective GS degeneracy N_eff=4. iv) For x>0.65, the magnetic
phase boundary splits into two transitions, with an intermediate phase
presenting incommensurate spin density waves features.Comment: 8 pages, 10 figure
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