On the Sensitivity of a Hollow Sphere as a Multi-modal Resonant Gravitational Wave Detector

We present a numerical analysis to simulate the response of a spherical resonant gravitational wave detector and to compute its sensitivity. Under the assump- tion of optimal filtering, we work out the sensitivity curve for a sphere first taking into account only a single transducer, and then using a coherent analysis of the whole set of transducers.Comment: 24 pages, 11 figures, published versio

Optical absorption parameters of amorphous carbon films from Forouhi–Bloomer and Tauc–Lorentz models: a comparative study

International audienceParametrization models of optical constants, namely Tauc-Lorentz (TL), Forouhi-Bloomer (FB) and modified FB models, were applied to the interband absorption of amorphous carbon films. The optical constants were determined by means of transmittance and reflectance measurements in the visible range. The studied films were prepared by rf sputtering and characterized for their chemical properties. The analytical models were also applied to other optical data published in the literature pertaining to films produced by various deposition techniques. The different approaches used to determine important physical parameters of the interband transition yielded different results. A figure-of-merit was introduced to check the applicability of the models and the results showed that FB modified for an energy dependence of the dipole matrix element adequately represents the interband transition in the amorphous carbons. Further, the modified FB model shows a relative superiority over the TL ones for concerning the determination of the band gap energy, as it is the only one to be validated by an independent, though indirect, gap measurement by x-ray photoelectron spectroscopy. Finally, the application of the modified FB model allowed us to establish some important correlations between film structure and optical absorption properties

Optimising the multiplex factor of the frequency domain multiplexed readout of the TES-based microcalorimeter imaging array for the X-IFU instrument on the Athena Xray observatory

Athena is a space-based X-ray observatory intended for exploration of the hot and energetic universe. One of the science instruments on Athena will be the X-ray Integrated Field Unit (X-IFU), which is a cryogenic X-ray spectrometer, based on a large cryogenic imaging array of Transition Edge Sensors (TES) based microcalorimeters operating at a temperature of 100mK. The imaging array consists of 3800 pixels providing 2.5 eV spectral resolution, and covers a field of view with a diameter of of 5 arc minutes. Multiplexed readout of the cryogenic microcalorimeter array is essential to comply with the cooling power and complexity constraints on a space craft. Frequency domain multiplexing has been under development for the readout of TES-based detectors for this purpose, not only for the X-IFU detector arrays but also for TES-based bolometer arrays for the Safari instrument of the Japanese SPICA observatory. This paper discusses the design considerations which are applicable to optimise the multiplex factor within the boundary conditions as set by the space craft. More specifically, the interplay between the science requirements such as pixel dynamic range, pixel speed, and cross talk, and the space craft requirements such as the power dissipation budget, available bandwidth, and electromagnetic compatibility will be discussed

Carbon nanotubes as a novel tool for vaccination against infectious diseases and cancer

Due to their unusual properties, carbon nanotubes have been extensively employed in electronics, nanotechnology and optics, amongst other. More recently, they have also been used as vehicles for drug and antigen delivery, the latter being a novel immunization strategy against infectious diseases and cancer. Here we discuss the potential of carbon nanotubes as an antigen delivery tool and suggest further directions in the field of vaccination. © 2013 Gottardi and Douradinha; licensee BioMed Central Ltd

Effects of exciton deconfinement on the transient photoluminescence from thermally activated delayed fluorescence host-guest systems

For thermally activated delayed fluorescence (TADF) host-guest systems used in organic light-emitting diodes, understanding of the transient photoluminescence (PL) measurements is crucial for accurate determination of the photophysical rates of the emitter. Here, we study how the PL is affected by triplet-exciton deconfinement from the guest to the host molecules. This deconfinement can complicate the analysis of the PL decay and potentially lead to a loss of efficiency. From an analytical model, we find that the transient PL intensity remains bi-exponential in the presence of exciton deconfinement for the case of fast triplet diffusion, albeit with a longer decay time of the delayed component. Deconfinement might, therefore, not always be recognizable from a single transient PL measurement. The role of deconfinement depends on the energetic disorder, the guest concentration, and the energy difference Δ E T between triplet-exciton energies on the host and guest molecules and is effectively suppressed for Δ E T &gt; - &gt; 0.2 eV. We find from analytical modeling and kinetic Monte Carlo simulations that the decay can become non-bi-exponential and even show a distinct third decay step. The shape of the decay curves depends on the characteristic times for guest-host transfer and host diffusion, relative to the prompt and delayed decay times of the TADF emitter. A comparison with available experimental data is included, finding qualitative agreement with dedicated deconfinement studies and indicating the influence of other processes for the often observed power-law decay at long time scales. </p

A Metabolomic Analysis of Cirrhotic Ascites.

Ascites is a common complication of decompensated liver cirrhosis, and yet relatively little is known about its biochemical composition. We conducted two metabolomic investigations, comparing the profile of ascites from 33 cirrhotic patients and postoperative peritoneal drainage fluid from 33 surgical patients (Experiment 1). The profile of paired ascites and plasma was also compared in 17 cirrhotic patients (Experiment 2). Gas chromatography-mass spectrometry-based metabolomics identified 29 metabolites that significantly characterized ascites fluid, whether postoperative drainage fluid or plasma were used as controls. Ten elevated amino acids (glutamine, proline, histidine, tyrosine, glycine, valine, threonine, methionine, lysine, phenylalanine) and seven diminished lipids (laurate, myristate, palmitate, oleate, vaccenate, stearate, cholesterol) largely comprised the cirrhotic ascites metabolomic phenotype that differed significantly (adjusted p &lt; 0.002 to 0.03) from peritoneal drainage fluid or plasma. The pattern of upregulated amino acids in cirrhotic ascites did not indicate albumin proteolysis by peritoneal bacteria. Bidirectional clustering showed that the more severe the cirrhosis, the lower the lipid concentration in ascitic fluid. The metabolomic compartment of ascites in patients with decompensated cirrhosis is characterized by increased amino acids and decreased lipids. These novel findings have potential relevance for diagnostic purposes

Lactobacillus paracasei A13 and high-pressure homogenization stress response

Sub-lethal high-pressure homogenization treatments applied to Lactobacillus paracasei A13 demonstrated to be a useful strategy to enhance technological and functional properties without detrimental effects on the viability of this strain. Modification of membrane fatty acid composition is reported to be the main regulatory mechanisms adopted by probiotic lactobacilli to counteract high-pressure stress. This work is aimed to clarify and understand the relationship between the modification of membrane fatty acid composition and the expression of genes involved in fatty acid biosynthesis in Lactobacillus paracasei A13, before and after the application of different sub-lethal hyperbaric treatments. Our results showed that Lactobacillus paracasei A13 activated a series of reactions aimed to control and stabilize membrane fluidity in response to high-pressure homogenization treatments. In fact, the production of cyclic fatty acids was counterbalanced by the unsaturation and elongation of fatty acids. The gene expression data indicate an up-regulation of the genes accA, accC, fabD, fabH and fabZ after high-pressure homogenization treatment at 150 and 200 MPa, and of fabK and fabZ after a treatment at 200 MPa suggesting this regulation of the genes involved in fatty acids biosynthesis as an immediate response mechanism adopted by Lactobacillus paracasei A13 to high-pressure homogenization treatments to balance the membrane fluidity. Although further studies should be performed to clarify the modulation of phospholipids and glycoproteins biosynthesis since they play a crucial role in the functional properties of the probiotic strains, this study represents an important step towards understanding the response mechanisms of Lactobacillus paracasei A13 to sub-lethal high-pressure homogenization treatments

A High-Throughput Mechanical Activator for Cartilage Engineering Enables Rapid Screening of in vitro Response of Tissue Models to Physiological and Supra-Physiological Loads

Articular cartilage is crucially influenced by loading during development, health, and disease. However, our knowledge of the mechanical conditions that promote engineered cartilage maturation or tissue repair is still incomplete. Current in vitro models that allow precise control of the local mechanical environment have been dramatically limited by very low throughput, usually just a few specimens per experiment. To overcome this constraint, we have developed a new device for the high throughput compressive loading of tissue constructs: the High Throughput Mechanical Activator for Cartilage Engineering (HiT-MACE), which allows the mechanoactivation of 6 times more samples than current technologies. With HiT-MACE we were able to apply cyclic loads in the physiological (e.g., equivalent to walking and normal daily activity) and supra-physiological range (e.g., injurious impacts or extensive overloading) to up to 24 samples in one single run. In this report, we compared the early response of cartilage to physiological and supra-physiological mechanical loading to the response to IL-1β exposure, a common but rudimentary in vitro model of cartilage osteoarthritis. Physiological loading rapidly upregulated gene expression of anabolic markers along the TGF-β1 pathway. Notably, TGF-β1 or serum was not included in the medium. Supra-physiological loading caused a mild catabolic response while IL-1β exposure drove a rapid anabolic shift. This aligns well with recent findings suggesting that overloading is a more realistic and biomimetic model of cartilage degeneration. Taken together, these findings showed that the application of HiT-MACE allowed the use of larger number of samples to generate higher volume of data to effectively explore cartilage mechanobiology, which will enable the design of more effective repair and rehabilitation strategies for degenerative cartilage pathologies

The Garisenda Tower in Bologna: Effects of degradation of selenite basement on its static behaviour

The Garisenda tower in Bologna, a 48 m tall structure with a square base of 7.45 meters per side, is characterized by an overall out of plumb of 3.32m in the South-East direction. Its construction dates back to the XI century and, due to its impressive leaning, in 1350–1353 the original height of 60m was reduced to the 48m of the present day (Cavani 1903; Giordano 2000). The tower can be seen as partitioned in a lower portion, with walls composed by two external leaves of selenite stones filled with rubble conglomerate, and an upper portion where the external leaves are made of masonry bricks. Recent investigations have proved that selenite blocks of the basement have been altered as a result of (a) exposition to high temperatures during important fires, that took place at the end of XIV and XVII centuries, and possibly because of the presence of forges (that were demolished at the end of the XIX centuries) and (b) high level of humidity in the inner lower part of the tower. This process has produced a gradual local disintegration of the selenite stones, leading in some case to a reduction of the original 50 to 60 cm thickness by an amount of about 20 cm. The contribution submitted to this conference is aimed at clarifying this important aspect, linked to the ageing and damage of structural stones and the related consequences in terms of stress distribution and concentrations that could induce fracture propagation and sudden collapse of the tower basement