The Invalidity of the Laplace Law for Biological Vessels and of Estimating Elastic Modulus from Total Stress vs. Strain: a New Practical Method

The quantification of the stiffness of tubular biological structures is often obtained, both in vivo and in vitro, as the slope of total transmural hoop stress plotted against hoop strain. Total hoop stress is typically estimated using the "Laplace law." We show that this procedure is fundamentally flawed for two reasons: Firstly, the Laplace law predicts total stress incorrectly for biological vessels. Furthermore, because muscle and other biological tissue are closely volume-preserving, quantifications of elastic modulus require the removal of the contribution to total stress from incompressibility. We show that this hydrostatic contribution to total stress has a strong material-dependent nonlinear response to deformation that is difficult to predict or measure. To address this difficulty, we propose a new practical method to estimate a mechanically viable modulus of elasticity that can be applied both in vivo and in vitro using the same measurements as current methods, with care taken to record the reference state. To be insensitive to incompressibility, our method is based on shear stress rather than hoop stress, and provides a true measure of the elastic response without application of the Laplace law. We demonstrate the accuracy of our method using a mathematical model of tube inflation with multiple constitutive models. We also re-analyze an in vivo study from the gastro-intestinal literature that applied the standard approach and concluded that a drug-induced change in elastic modulus depended on the protocol used to distend the esophageal lumen. Our new method removes this protocol-dependent inconsistency in the previous result.Comment: 34 pages, 13 figure

A Fast Frequency Sweep – Green’s Function Based Analysis of Substrate Integrated Waveguide

In this paper, a fast frequency sweep technique is applied to the analysis of Substrate Integrated Waveguides performed with a Green’s function technique. The well-known Asymptotic Waveform Evaluation technique is used to extract the Padè approximation of the frequency response of Substrate Integrated Waveguides devices. The analysis is extended to a large frequency range by adopting the Complex Frequency Hopping algorithm. It is shown that, with this technique, CPU time can be reduced of almost one order of magnitude with respect to a point by point computation

A novel DR/NIR T-shaped aiegen: Synthesis and x-ray crystal structure study

We developed a new benzodifuran derivative as the condensation product between 2,6-diamino-4-(4-nitrophenyl)benzo[1,2-b:4,5-b’]difuran-3,7-dicarboxylate and 3-hydroxy-2-naphthaldehyde. The intramolecular hydrogen-bond interactions in the terminal half-salen moieties produce a sterically encumbered highly conjugated main plane and a D-A-D (donor-acceptor-donor) T-shaped structure. The novel AIEgen (aggregation-induced enhanced emission generator) fulfils the requirement of RIR (restriction of intramolecular rotation) molecules. DR/NIR (deep red/near infrared) emission was recorded in solution and in the solid state, with a noteworthy photoluminescence quantum yield recorded on the neat crystals which undergo some mechanochromism. The crystal structure study of the probe from data collected at a synchrotron X-ray source shows a main aromatic plane π-stacked in a columnar arrangement

Giant cell arteritis and innovative treatments

Purpose of reviewGiant cell arteritis (GCA) is an idiopathic and persistent condition characterized by granulomatous vasculitis of the medium and large vessels with overlapping phenotypes, including conventional cranial arteritis and extra-cranial GCA, also known as large-vessel GCA. Vascular problems linked with large vessel involvement may partly be caused by delayed diagnosis, emphasizing the necessity of early detection and the fast beginning of appropriate therapy. Glucocorticoids are the cornerstone of treatment for GCA, but using them for an extended period has numerous, often severe, side effects.Recent findingsclinical practice and novel discoveries on the pathogenic pathways suggest that steroid-free biologic treatments may be efficient and safe for GCA patients.Summarysince now, only Tocilizumab is approved for GCA treatment, but several drugs are currently used, and ongoing trials could give both researchers and patients novel therapeutic strategies for induction, maintenance, and prevention of relapse of GCA. The aims of this work is to synthesize evidence from current studies present in scientific literature about innovative treatment of Giant cell artheritis

State of the art: the treatment of systemic lupus erythematosus

Purpose of reviewSystemic lupus erythematosus (SLE) is a systemic autoimmune disease with dysregulated cells in the immune system. The disease affects organs like kidneys, nervous system, joints, and skin. To manage SLE effectively, novel treatments targeting immune system components have been developed. This review investigates the therapeutic potential of existing targeted therapies and explores future innovative approaches for well tolerated, personalized treatment.Recent findingsSLE treatment involves cytokine targets and specific immunologic pathways, with even small molecules involved.SummaryThe advanced therapeutic options in SLE management give clinicians more tools to control disease activity according to personalized medicine

Rex1p Deficiency Leads to Accumulation of Precursor Initiator tRNA\u3csup\u3eMet\u3c/sup\u3e and Polyadenylation of Substrate RNAs in \u3cem\u3eSaccharomyces cerevisiae\u3c/em\u3e

A synthetic genetic array was used to identify lethal and slow-growth phenotypes produced when a mutation in TRM6, which encodes a tRNA modification enzyme subunit, was combined with the deletion of any non-essential gene in Saccharomyces cerevisiae. We found that deletion of the REX1 gene resulted in a slow-growth phenotype in the trm6-504 strain. Previously, REX1 was shown to be involved in processing the 3′ ends of 5S rRNA and the dimeric tRNAArg-tRNAAsp. In this study, we have discovered a requirement for Rex1p in processing the 3′ end of tRNAiMet precursors and show that precursor tRNAiMet accumulates in a trm6-504 rex1Δ strain. Loss of Rex1p results in polyadenylation of its substrates, including tRNAiMet, suggesting that defects in 3′ end processing can activate the nuclear surveillance pathway. Finally, purified Rex1p displays Mg2+-dependent ribonuclease activity in vitro, and the enzyme is inactivated by mutation of two highly conserved amino acids

Bifid median nerve as a determinant of carpal tunnel syndrome recurrence after endoscopic procedures. A case report

A number of complications have been associated with endoscopic technique in treating carpal tunnel syndrome (CTS). We observed a female patient who had previously undergone endoscopic surgery for CTS. Shortly after surgery, this patient complained of pain, numbness and strength deficiency, as severe as it was before the operation. A new, open, surgical procedure was performed. During this second-look surgery, we found a bifid median nerve, which divided into two branches at the second third of the forearm, proximal to the flexor retinaculum. We strongly suggest a careful exploration of the median nerve in the carpal tunnel. Moreover, we believe that an extensive preoperative assessment of median nerve morphology and function is mandatory prior to endoscopic approach in treating CTS

The seismic performance of a earth dam by different displacementbased methods

The performance-based design of earth dams and the rehabilitation of existing ones require the evaluation of seismic performance based on permanent displacements caused by expected the earthquake. The paper reports a comparison between different methods with increasing complexity for estimating seismic displacements: simplified rigid block method, based on empirical relationships (Bray and Rathje, 1998; Tropeano et al., 2009); simplified uncoupled method, again based on the sliding block analysis, but accounting for soil deformability; coupled ‘stick-slip’ approach, based on a 1D lumped mass model to calculate together dynamic response of the site and movement of sliding block (Tropeano et al., 2011); 2D finite differences analyses by the FLAC code, reproducing the heterogeneity of soil and topographic effects. The methods were applied to the case of the dam of Marello mountain across the Angitola river (Southern Italy). The parameters for static and dynamic geotechnical characterization of subsoil model have been taken from the results of the site investigation published in technical reports. The spectral shape and peak ground acceleration specified by the Italian Seismic Hazard Map, representative of input motion on outcropping bedrock, allowed to choose a set of spectrum-compatible acceleration time histories to simulate the seismic input. The sliding displacements predicted using simplified method resulted strongly dependent on topographic coefficient. Both uncoupled and coupled approaches have shown conservative permanent displacements compared to Newmark method. The average displacement of the sliding block by two-dimensional finite difference analysis, considering the stiffness variability related to depth, results comparable with values obtained by other methods

Innovative 3-D Printing Processing Techniques for Flexible and Wearable Planar Rectennas

This work demonstrates the use of a low-cost, lossy, flexible substrate processed by novel 3-D printing techniques which significantly mitigate its intrinsic losses, thus providing performance comparable to those of traditional substrates. These processing techniques are applied to both microstrip and coplanar waveguide structures; they are first derived theoretically, starting from the electromagnetic theory of modes propagation, then numerically validated by full-wave analysis, and finally experimentally verified. The design of a miniaturized 868 MHz rectenna, adopting a coplanar-fed patch antenna based on the proposed fabrication approach, is presented. By means of nonlinear/electromagnetic co-design, the antenna is directly matched to the rectifier. A 30-dB power range starting from -20 dBm is considered. Direct matching allows to get rid of a dedicated matching network and its associated losses, resulting in a slight efficiency increase and a significant reduction of the overall dimensions. Finally, the 3-Dprinted prototype is presented: the overall rectenna performance proves that design freedom enabled by 3-D printing paves the way to the use of low-cost flexible dielectric materials, even with poor electromagnetic properties, to realize wearable battery-free wireless nodes