26 research outputs found
The Genomic Signature of Crop-Wild Introgression in Maize
The evolutionary significance of hybridization and subsequent introgression
has long been appreciated, but evaluation of the genome-wide effects of these
phenomena has only recently become possible. Crop-wild study systems represent
ideal opportunities to examine evolution through hybridization. For example,
maize and the conspecific wild teosinte Zea mays ssp. mexicana, (hereafter,
mexicana) are known to hybridize in the fields of highland Mexico. Despite
widespread evidence of gene flow, maize and mexicana maintain distinct
morphologies and have done so in sympatry for thousands of years. Neither the
genomic extent nor the evolutionary importance of introgression between these
taxa is understood. In this study we assessed patterns of genome-wide
introgression based on 39,029 single nucleotide polymorphisms genotyped in 189
individuals from nine sympatric maize-mexicana populations and reference
allopatric populations. While portions of the maize and mexicana genomes were
particularly resistant to introgression (notably near known
cross-incompatibility and domestication loci), we detected widespread evidence
for introgression in both directions of gene flow. Through further
characterization of these regions and preliminary growth chamber experiments,
we found evidence suggestive of the incorporation of adaptive mexicana alleles
into maize during its expansion to the highlands of central Mexico. In
contrast, very little evidence was found for adaptive introgression from maize
to mexicana. The methods we have applied here can be replicated widely, and
such analyses have the potential to greatly informing our understanding of
evolution through introgressive hybridization. Crop species, due to their
exceptional genomic resources and frequent histories of spread into sympatry
with relatives, should be particularly influential in these studies
Patients visiting the complementary medicine clinic for pain: a cross sectional study
<p>Abstract</p> <p>Background</p> <p>Pain is one of the most common reasons for seeking medical care. The purpose of this study was to characterize patients visiting the complementary medicine clinic for a pain complaint.</p> <p>Methods</p> <p>This is a cross-sectional study. The study took place at Clalit Health Services (CHS) complementary clinic in Beer-Sheva, Israel. Patients visiting the complementary clinic, aged 18 years old and older, Hebrew speakers, with a main complaint of pain were included. Patients were recruited consecutively on random days of the month during a period of six months. Main outcome measures were: pain levels, location of pain, and interference with daily activities. Once informed consent was signed patients were interviewed using a structured questionnaire by a qualified nurse. The questionnaire included socio-demographic data, and the Brief Pain Inventory (BPI).</p> <p>Results</p> <p>Three-hundred and ninety-five patients were seen at the complementary medicine clinic during the study period, 201 (50.8%) of them met the inclusion criteria. Of them, 163 (81.1%) agreed to participate in the study and were interviewed. Pain complaints included: 69 patients (46.6%) with back pain, 65 (43.9%) knee pain, and 28 (32.4%) other limbs pain. Eighty-two patients (50.3%) treated their pain with complementary medicine as a supplement for their conventional treatment, and 55 (33.7%) felt disappointed from the conventional medicine experience. Eighty-three patients (50.9%) claimed that complementary medicine can result in better physical strength, or better mental state 51 (31.3%). Thirty-seven patients (22.7%) were hoping that complementary medicine will prevent invasive procedures.</p> <p>Conclusion</p> <p>Given the high proportion of patients with unsatisfactory pain relief using complementary and alternative medicine (CAM), general practitioners should gain knowledge about CAM and CAM providers should gain training in pain topics to improve communication and counsel patients. More clinical research to evaluate safety and efficiency of CAM for pain is needed to provide evidence based counseling.</p
Timing and Tempo of Early and Successive Adaptive Radiations in Macaronesia
The flora of Macaronesia, which encompasses five Atlantic archipelagos (Azores, Canaries, Madeira, Cape Verde, and Salvage), is exceptionally rich and diverse
Maze Solving Using Fatty Acid Chemistry
This
study demonstrates that the Marangoni flow in a channel network
can solve maze problems such as exploring and visualizing the shortest
path and finding all possible solutions in a parallel fashion. The
Marangoni flow is generated by the pH gradient in a maze filled with
an alkaline solution of a fatty acid by introducing a hydrogel block
soaked with an acid at the exit. The pH gradient changes the protonation
rate of fatty acid molecules, which translates into the surface tension
gradient at the liquid–air interface through the maze. Fluid
flow maintained by the surface tension gradient (Marangoni flow) can
drag water-soluble dye particles toward low pH (exit) at the liquid–air
interface. Dye particles placed at the entrance of the maze dissolve
during this motion, thus exhibiting and finding the shortest path
and all possible paths in a maze
The double solid solution (Zr, Nb)₂(Al, Sn)C MAX phase: a steric stability approach
The addition of Nb and Sn to Zr2AlC is investigated, targeting the synthesis of a Zr-rich bulk MAX phase free of ZrC. The 211 phase formation in the two quaternary Zr-Nb-Al-C and Zr-Al-Sn-C systems is evaluated. Solubility over the entire compositional range in (Zr, Nb)2AlC and Zr2(Al, Sn)C is observed. In terms of effectiveness, the addition of Sn is preferred over the addition of Nb, as the former is selectively incorporated into the 211 structure. A combinatorial approach results in the formation of phase-pure (Zr0.8, Nb0.2)2(Al0.5, Sn0.5)C. The effect of the added solutes on the microstructure and crystallographic parameters is investigated. The addition of Nb and Sn reduces the distortion parameter of the trigonal prism compared to pure Zr2AlC. Therefore, an attempt is made to establish a more general stability criterion for the M2AC structure based on the steric relationship between the atoms in the M6A trigonal prism. Inspired by the Hume-Rothery rules, it is suggested that comparable atomic radii of the M- and A-atoms provide a good starting point to obtain a stable 211 MAX phase.status: publishe
Magnetic ordering in the nano laminar ternary Mn2AlB2 using neutron and X ray diffraction
International audienceThe nano-laminar ceramic Mn2AlB2 belongs to the orthorhombic M2AlB2 system (M = Cr, Fe, Mn), in which Fe2AlB2 was shown to be ferromagnetic near room temperature. Herein, the magnetic state of Mn2Al11B2 is investigated using magnetization measurements, in the 5–360 K temperature range, X-ray diffraction in the 300–800 K range and neutron diffraction in the 1.6–300 K range. From the totality of our results we conclude that below ∼390 K Mn2AlB2 becomes a canted antiferromagnet. The crystallographic unit cell is doubled along the c axis (i.e. a propagation vector of 0,0,1/2) and the ordered Mn magnetic moments are oriented either along the a or the b axes, with a magnetic moment reaching 0.71(2) µB per Mn atom at 1.6 K. This magnetic structure is in excellent agreement with, and contributes to the validity of the recently reported theoretical calculations for the (Fe1-xMnx)2AlB2 system