264 research outputs found
First record of Eunotosaurus (Amniota: Parareptilia) from the Eastern Cape.
Main articleEunotosaurus is a rare tetrapod fossil until recently known only from the Tapinocephaluszone of
the main Karoo basin of Cape Province. A single specimen has recently been collected in the Free
State (Weiman, pers. com.). This paper describes a new find from the Eastern Cape, where outcrops
of Karoo rocks are scarce. The new specimen adds previously unknown morphological detail, particularly about the limbs. Phylogenetic affinities are clearly with the Parareptilia.
particularly about the limbs. Phy logene tic affinities are clearly with the Parareptilia.Non
Integration of multiple platforms for the analysis of multifluorescent marking technology applied to pediatric GBM and dipg
The intratumor heterogeneity represents one of the most difficult challenges for the development of effective therapies to treat pediatric glioblastoma (pGBM) and diffuse intrinsic pontine glioma (DIPG). These brain tumors are composed of heterogeneous cell subpopulations that coexist and cooperate to build a functional network responsible for their aggressive phenotype. Understanding the cellular and molecular mechanisms sustaining such network will be crucial for the identification of new therapeutic strategies. To study more in-depth these mechanisms, we sought to apply the Multifluorescent Marking Technology. We generated multifluorescent pGBM and DIPG bulk cell lines randomly expressing six different fluorescent proteins and from which we derived stable optical barcoded single cell-derived clones. In this study, we focused on the application of the Multifluorescent Marking Technology in 2D and 3D in vitro/ex vivo culture systems. We discuss how we integrated different multimodal fluorescence analysis platforms, identifying their strengths and limitations, to establish the tools that will enable further studies on the intratumor heterogeneity and interclonal interactions in pGBM and DIPG
Three-dimensional localization of ultracold atoms in an optical disordered potential
We report a study of three-dimensional (3D) localization of ultracold atoms
suspended against gravity, and released in a 3D optical disordered potential
with short correlation lengths in all directions. We observe density profiles
composed of a steady localized part and a diffusive part. Our observations are
compatible with the self-consistent theory of Anderson localization, taking
into account the specific features of the experiment, and in particular the
broad energy distribution of the atoms placed in the disordered potential. The
localization we observe cannot be interpreted as trapping of particles with
energy below the classical percolation threshold.Comment: published in Nature Physics; The present version is the initial
manuscript (unchanged compared to version 1); The published version is
available online at
http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2256.htm
Anderson localization in Bragg-guiding arrays with negative defects
We show that Anderson localization is possible in waveguide arrays with
periodically-spaced defect waveguides having lower refractive index. Such
localization is mediated by Bragg reflection, and it takes place even if
diagonal or off-diagonal disorder affects only defect waveguides. For
off-diagonal disorder the localization degree of the intensity distributions
monotonically grows with increasing disorder. In contrast, under appropriate
conditions, increasing diagonal disorder may result in weaker localization.Comment: 4 pages, 5 figures, to appear in Optics Letter
Fractal superconductivity near localization threshold
We develop a semi-quantitative theory of electron pairing and resulting
superconductivity in bulk "poor conductors" in which Fermi energy is
located in the region of localized states not so far from the Anderson mobility
edge . We review the existing theories and experimental data and argue
that a large class of disordered films is described by this model.
Our theoretical analysis is based on the analytical treatment of pairing
correlations, described in the basis of the exact single-particle eigenstates
of the 3D Anderson model, which we combine with numerical data on eigenfunction
correlations. Fractal nature of critical wavefunction's correlations is shown
to be crucial for the physics of these systems.
We identify three distinct phases: 'critical' superconductive state formed at
, superconducting state with a strong pseudogap, realized due to
pairing of weakly localized electrons and insulating state realized at
still deeper inside localized band. The 'critical' superconducting phase is
characterized by the enhancement of the transition temperature with respect to
BCS result, by the inhomogeneous spatial distribution of superconductive order
parameter and local density of states. The major new feature of the
pseudo-gaped state is the presence of two independent energy scales:
superconducting gap , that is due to many-body correlations and a new
"pseudogap" energy scale which characterizes typical binding energy
of localized electron pairs and leads to the insulating behavior of the
resistivity as a function of temperature above superconductive . Two gap
nature of the "pseudo-gaped superconductor" is shown to lead to a number of
unusual physical properties.Comment: 110 pages, 39 figures. The revised version corrects a number of
typos, adds references and discussion of recent result
A Green's function approach to transmission of massless Dirac fermions in graphene through an array of random scatterers
We consider the transmission of massless Dirac fermions through an array of
short range scatterers which are modeled as randomly positioned -
function like potentials along the x-axis. We particularly discuss the
interplay between disorder-induced localization that is the hallmark of a
non-relativistic system and two important properties of such massless Dirac
fermions, namely, complete transmission at normal incidence and periodic
dependence of transmission coefficient on the strength of the barrier that
leads to a periodic resonant transmission. This leads to two different types of
conductance behavior as a function of the system size at the resonant and the
off-resonance strengths of the delta function potential. We explain this
behavior of the conductance in terms of the transmission through a pair of such
barriers using a Green's function based approach. The method helps to
understand such disordered transport in terms of well known optical phenomena
such as Fabry Perot resonances.Comment: 22 double spaced single column pages. 15 .eps figure
Localization of ultrasound in a three-dimensional elastic network
After exactly half a century of Anderson localization, the subject is more
alive than ever. Direct observation of Anderson localization of electrons was
always hampered by interactions and finite temperatures. Yet, many theoretical
breakthroughs were made, highlighted by finite-size scaling, the
self-consistent theory and the numerical solution of the Anderson tight-binding
model. Theoretical understanding is based on simplified models or
approximations and comparison with experiment is crucial. Despite a wealth of
new experimental data, with microwaves, light, ultrasound and cold atoms, many
questions remain, especially for three dimensions. Here we report the first
observation of sound localization in a random three-dimensional elastic
network. We study the time-dependent transmission below the mobility edge, and
report ``transverse localization'' in three dimensions, which has never been
observed previously with any wave. The data are well described by the
self-consistent theory of localization. The transmission reveals non-Gaussian
statistics, consistent with theoretical predictions.Comment: Final published version, 5 pages, 4 figure
Contribution of NFP LysM Domains to the Recognition of Nod Factors during the Medicago truncatula/Sinorhizobium meliloti Symbiosis
The root nodule nitrogen fixing symbiosis between legume plants and soil bacteria called rhizobia is of great agronomical and ecological interest since it provides the plant with fixed atmospheric nitrogen. The establishment of this symbiosis is mediated by the recognition by the host plant of lipo-chitooligosaccharides called Nod Factors (NFs), produced by the rhizobia. This recognition is highly specific, as precise NF structures are required depending on the host plant. Here, we study the importance of different LysM domains of a LysM-Receptor Like Kinase (LysM-RLK) from Medicago truncatula called Nod factor perception (NFP) in the recognition of different substitutions of NFs produced by its symbiont Sinorhizobium meliloti. These substitutions are a sulphate group at the reducing end, which is essential for host specificity, and a specific acyl chain at the non-reducing end, that is critical for the infection process. The NFP extracellular domain (ECD) contains 3 LysM domains that are predicted to bind NFs. By swapping the whole ECD or individual LysM domains of NFP for those of its orthologous gene from pea, SYM10 (a legume plant that interacts with another strain of rhizobium producing NFs with different substitutions), we showed that NFP is not directly responsible for specific recognition of the sulphate substitution of S. meliloti NFs, but probably interacts with the acyl substitution. Moreover, we have demonstrated the importance of the NFP LysM2 domain for rhizobial infection and we have pinpointed the importance of a single leucine residue of LysM2 in that step of the symbiosis. Together, our data put into new perspective the recognition of NFs in the different steps of symbiosis in M. truncatula, emphasising the probable existence of a missing component for early NF recognition and reinforcing the important role of NFP for NF recognition during rhizobial infection
Patient Selection in One Anastomosis/Mini Gastric Bypass—an Expert Modified Delphi Consensus
Purpose: One anastomosis/mini gastric bypass (OAGB/MGB) is up to date the third most performed obesity and metabolic procedure worldwide, which recently has been endorsed by ASMBS. The main criticisms are the risk of bile reflux, esophageal cancer, and malnutrition. Although IFSO has recognized this procedure, guidance is needed regarding selection criteria. To give clinicians a daily support in performing the right patient selection in OAGB/MGB, the aim of this paper is to generate clinical guidelines based on an expert modified Delphi consensus.
Methods: A committee of 57 recognized bariatric surgeons from 24 countries created 69 statements. Modified Delphi consensus voting was performed in two rounds. An agreement/disagreement among ≥ 70.0% of the experts was considered to indicate a consensus.
Results: Consensus was achieved for 56 statements. Remarkably, ≥ 90.0% of the experts felt that OAGB/MGB is an acceptable and suitable option "in patients with Body mass index (BMI) > 70, BMI > 60, BMI > 50 kg/m2 as a one-stage procedure," "as the second stage of a two-stage bariatric surgery after Sleeve Gastrectomy for BMI > 50 kg/m2 (instead of BPD/DS)," and "in patients with weight regain after restrictive procedures. No consensus was reached on the statement that OAGB/MGB is a suitable option in case of resistant Helicobacter pylori. This is likely as there is a concern that this procedure is associated with reflux and its related long-term complications including risk of cancer in the esophagus or stomach. Also no consensus reached on OAGB/MGB as conversional surgery in patients with GERD after restrictive procedures. Consensus for disagreement was predominantly achieved "in case of intestinal metaplasia of the stomach" (74.55%), "in patients with severe Gastro Esophageal Reflux Disease (GERD)(C,D)" (75.44%), "in patients with Barrett's metaplasia" (89.29%), and "in documented insulinoma" (89.47%).
Conclusion: Patient selection in OAGB/MGB is still a point of discussion among experts. There was consensus that OAGB/MGB is a suitable option in elderly patients, patients with low BMI (30-35 kg/m2) with associated metabolic problems, and patients with BMIs more than 50 kg/m2 as one-stage procedure. OAGB/MGB can also be a safe procedure in vegetarian and vegan patients. Although OAGB/MGB can be a suitable procedure in patients with large hiatal hernia with concurrent hiatal hernia, it should not be offered to patients with grade C or D esophagitis or Barrett's metaplasia.info:eu-repo/semantics/publishedVersio
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