499 research outputs found
Application of multireïŹection grazing incidence method for stress measurements in polished AlâMg alloy and CrN coating
Multi-reïŹection grazing incidence geometry, referred to as MGIXD, characterized by a small and constant incidence angle, was applied to measure low surface stresses in very thin layers of AlâMg alloy and CrN coating. These two materials were selected in order to deal with the low and high levels of residual stress, respectively. The inïŹuence of different mechanical treatments on residual stresses was studied for AlâMg samples. It was found that both rolling and mechanical polishing inïŹuence the distribution and amplitude of residual stress in surface layers. In the case of CrN coating, a very high compressive stress was generated during the deposition process. The stress distributions determined by the MGIXD method is in good agreement with the classic sin2 technique results for all studied samples. In performing stress measurements for a powder sample, it was found that the application of the Göbel mirror in the incident beam strongly reduces statistical and misalignment errors. Additionally, the root mean square values of the third order lattice strain within diffracting grains were determined
Bilateral double-layered patella in a patient with advanced knee osteoarthritis
Double layered patella (DLP) is a rare anomaly of the patella that may go undiagnosed, especially in patients with progressive knee dysfunction and early degenerative changes. Clinical symptoms such as motion-dependent pain and anterior knee pain most typically occur in adolescents or young adults; however, gradually increasing pain and early generalised degenerative changes have also been seen in patients over 40 years old. Diagnosis of DLP could be difficult, especially in cases with coexisting arthrosis. DLP is considered to be pathognomonic for the diagnosis of multiple epiphyseal dysplasia and usually coexists with other anomalies seen in this syndrome, such as hip dysplasia. In extremely rare cases, DLP can occur as a solitary disorder. The prevalence of such cases, however, is unknown, and they could be easily misdiagnosed. Computed tomography and magnetic resonance imaging are the most sensitive radiological methods used in DLP diagnosis. This case report presents a case of a bilateral DLP incidentally found in a 47-year-old patient with advanced arthritis referred for arthroplasty because of increasing symptoms of knee joint failure with no other abnormalities recorded. An important goal of our case study is to raise the awareness of this abnormality with radiologists and orthopaedic surgeons
Learning and generation of long-range correlated sequences
We study the capability to learn and to generate long-range, power-law
correlated sequences by a fully connected asymmetric network. The focus is set
on the ability of neural networks to extract statistical features from a
sequence. We demonstrate that the average power-law behavior is learnable,
namely, the sequence generated by the trained network obeys the same
statistical behavior. The interplay between a correlated weight matrix and the
sequence generated by such a network is explored. A weight matrix with a
power-law correlation function along the vertical direction, gives rise to a
sequence with a similar statistical behavior.Comment: 5 pages, 3 figures, accepted for publication in Physical Review
Decreased levels of the gelsolin plasma isoform in patients with rheumatoid arthritis
Introduction Gelsolin is an intracellular actin-binding protein involved in cell shape changes, cell motility, and apoptosis. An extracellular gelsolin isoform, plasma gelsolin circulates in the blood of healthy individuals at a concentration of mg/L and has been suggested to be a key component of an extracellular actin-scavenging system during tissue damage. Levels of plasma gelsolin decrease during acute injury and inflammation, and administration of recombinant plasma gelsolin to animals improves outcomes following sepsis or burn injuries. In the present study, we investigated plasma gelsolin in patients with rheumatoid arthritis.Methods Circulating and intra-articular levels of plasma gelsolin were measured in 78 patients with rheumatoid arthritis using a functional (pyrene-actin nucleation) assay and compared with 62 age- and gender-matched healthy controls.Results Circulating plasma gelsolin levels were significantly lower in patients with rheumatoid arthritis compared with healthy controls ( versus mg/L, P = 0.0002). The patients' intra-articular plasma gelsolin levels were significantly lower than in the paired plasma samples ( versus mg/L, P = 0.0001). Actin was detected in the synovial fluids of all but four of the patients, and immunoprecipitation experiments identified gelsolin-actin complexes.Conclusions The plasma isoform of gelsolin is decreased in the plasma of patients with rheumatoid arthritis compared with healthy controls. The reduced plasma concentrations in combination with the presence of actin and gelsolin-actin complexes in synovial fluids suggest a local consumption of this potentially anti-inflammatory protein in the inflamed joint
Application of multireïŹection grazing incidence method for stress measurements in polished AlâMg alloy and CrN coating
Multi-reïŹection grazing incidence geometry, referred to as MGIXD, characterized by a small and constant incidence angle, was applied to measure low surface stresses in very thin layers of AlâMg alloy and CrN coating. These two materials were selected in order to deal with the low and high levels of residual stress, respectively. The inïŹuence of different mechanical treatments on residual stresses was studied for AlâMg samples. It was found that both rolling and mechanical polishing inïŹuence the distribution and amplitude of residual stress in surface layers. In the case of CrN coating, a very high compressive stress was generated during the deposition process. The stress distributions determined by the MGIXD method is in good agreement with the classic sin2 technique results for all studied samples. In performing stress measurements for a powder sample, it was found that the application of the Göbel mirror in the incident beam strongly reduces statistical and misalignment errors. Additionally, the root mean square values of the third order lattice strain within diffracting grains were determined
A toy model of the five-dimensional universe with the cosmological constant
A value of the cosmological constant in a toy model of the five-dimensional
universe is calculated in such a manner that it remains in agreement with both
astronomical observations and the quantum field theory concerning the
zero-point fluctuations of the vacuum. The (negative) cosmological constant is
equal to the inverse of the Planck length squared, which means that in the toy
model the vanishing of the observed value of the cosmological constant is a
consequence of the existence of an energy cutoff exactly at the level of the
Planck scale. In turn, a model for both a virtual and a real
particle-antiparticle pair is proposed which describes properly some energetic
properties of both the vacuum fluctuations and created particles, as well as it
allows one to calculate the discrete "bare" values of an elementary-particle
mass, electric charge and intrinsic angular momentum (spin) at the energy
cutoff. The relationships between the discussed model and some phenomena such
as the Zitterbewegung and the Unruh-Davies effect are briefly analyzed, too.
The proposed model also allows one to derive the Lorentz transformation and the
Maxwell equations while considering the properties of the vacuum filled with
the sea of virtual particles and their antiparticles. Finally, the existence of
a finite value of the vacuum-energy density resulting from the toy model leads
us to the formulation of dimensionless Einstein field equations which can be
derived from the Lagrangian with a dimensionless (naively renormalized)
coupling constant.Comment: 52 pages, 1 figure; a post-final, rewritten version with a number of
new remarks and conclusion
Strigolactones inhibit auxin feedback on PIN-dependent auxin transport canalization
Directional transport of the phytohormone auxin is a versatile, plant-specific mechanism regulating many aspects of plant development. The recently identified plant hormones, strigolactones (SLs), are implicated in many plant traits; among others, they modify the phenotypic output of PIN-FORMED (PIN) auxin transporters for fine-tuning of growth and developmental responses. Here, we show in pea and Arabidopsis that SLs target processes dependent on the canalization of auxin flow, which involves auxin feedback on PIN subcellular distribution. D14 receptor- and MAX2 F-box-mediated SL signaling inhibits the formation of auxin-conducting channels after wounding or from artificial auxin sources, during vasculature de novo formation and regeneration. At the cellular level, SLs interfere with auxin effects on PIN polar targeting, constitutive PIN trafficking as well as clathrin-mediated endocytosis. Our results identify a non-transcriptional mechanism of SL action, uncoupling auxin feedback on PIN polarity and trafficking, thereby regulating vascular tissue formation and regeneration
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