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

Learning from a well-documented geotechnical cold case : the Two Towers of Bologna, Italy.

The Garisenda Tower and the Asinelli Tower, also widely known as the Two Towers, are the best preserved and famous medieval towers in the city of Bologna (Northern Italy). Standing one close to the other, right in the heart of the city centre, the Two Towers are delicate remains of the old towered city, which counted more than 75 towers in the 12th century. The foundations of historic towers and the surrounding soil often hide major hazards for the long-term preservation of these heritage structures. The initial fundamental step to this aim is indeed a deep understanding of their original conception, foundations and subsoil. However, the idea that also such elements are an integral part of the overall structure, and thus subjected to the same conservation rules, is relatively new. The present paper outlines the investigation criteria applied to the soil-foundation systems of the Two Towers of Bologna and describes the authenticity of their characteristics, through the interpretation of new experimental data and the analysis of historical documents. A geotechnical perspective on this type of monuments turns out to be crucial in order to effectively understand the soil-structure interaction mechanisms, which govern their safety conditions over time. This study also aims to better understand the reasons why the Two Towers of Bologna, despite their numerous similarities, have reached completely different structural configurations. The methodology described to investigate this case study, which required the integration of several aspects, can be usefully applied to any historic tower

Sensitivity of the spherical gravitational wave detector MiniGRAIL operating at 5 K

We present the performances and the strain sensitivity of the first spherical gravitational wave detector equipped with a capacitive transducer and read out by a low noise two-stage SQUID amplifier and operated at a temperature of 5 K. We characterized the detector performance in terms of thermal and electrical noise in the system output sygnal. We measured a peak strain sensitivity of $1.5\cdot 10^{-20} Hz^{-1/2}$ at 2942.9 Hz. A strain sensitivity of better than $5\cdot 10{-20}Hz{-1/2}$ has been obtained over a bandwidth of 30 Hz. We expect an improvement of more than one order of magnitude when the detector will operate at 50 mK. Our results represent the first step towards the development of an ultracryogenic omnidirectional detector sensitive to gravitational radiation in the 3kHz range.Comment: 8 pages, 5 figures, submitted to Physical Review

Distinct molecular forms of β-catenin are targeted to adhesive or transcriptional complexes

β-Catenin plays essential roles in both cell–cell adhesion and Wnt signal transduction, but what precisely controls β-catenin targeting to cadherin adhesive complexes, or T-cell factor (TCF)-transcriptional complexes is less well understood. We show that during Wnt signaling, a form of β-catenin is generated that binds TCF but not the cadherin cytoplasmic domain. The Wnt-stimulated, TCF-selective form is monomeric and is regulated by the COOH terminus of β-catenin, which selectively competes cadherin binding through an intramolecular fold-back mechanism. Phosphorylation of the cadherin reverses the TCF binding selectivity, suggesting another potential layer of regulation. In contrast, the main cadherin-binding form of β-catenin is a β-catenin–α-catenin dimer, indicating that there is a distinct molecular form of β-catenin that can interact with both the cadherin and α-catenin. We propose that participation of β-catenin in adhesion or Wnt signaling is dictated by the regulation of distinct molecular forms of β-catenin with different binding properties, rather than simple competition between cadherins and TCFs for a single constitutive form. This model explains how cells can control whether β-catenin is used independently in cell adhesion and nuclear signaling, or competitively so that the two processes are coordinated and interrelated

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

Primi risultati del progetto LIFE+ sulle analisi microbiologiche delle acque nel Parco dei Gessi dell’Emilia Romagna

Dal 2010 è in corso il Progetto Life + 08NAT/IT/000369 “Gypsum” 2, cofinanziato dall’Unione Europea, finalizzato alla tutela e gestione dei principali ambienti gessosi dell’Emilia Romagna. Nell’ambito dell’Azione A3 è previsto un monitoraggio pluriennale dei principali acquiferi carsici sotto l’aspetto chimico e microbiologico. Nel corso del primo anno sono state analizzate le acque carsiche su circa 50 punti di controllo (inghiottitoi, fiumi, torrenti in grotta, e risorgenti). In generale l’obiettivo di questa sperimentazione è quello di valutare l’impatto di sostanze di origine agricola o di altre forme di inquinamento, legate ad insediamenti o attività antropiche o fattori naturali, in acque di grotta. La sperimentazione è stata sviluppata tramite tecniche microbiologiche classiche e di biologia molecolare (PCR 16S rRNA e PCR-DGGE), finalizzate alla caratterizzazione delle popolazioni microbiche presenti nei diversi siti di prelievo e alla determinazione di loro eventuali variazioni e/o evoluzioni. I valori di carica microbica totale determinati oscillavano da un massimo di 3.32 ad un minimo di 0.18 log UFC/ ml e da un massimo di 2.26 fino a valori al di sotto del limite di determinazione (1 log UFC/ml) per quanto riguarda i coliformi totali e fecali. Le analisi genetiche hanno mostrato la presenza di numerosi specie batteriche (Agrobacterium tumefaciens, Pseudomonas spp., Rahnella aquatilis, Stenotrophomonas maltophilia, Pedobacter swuonensis, Enterobacter spp., Aeromonas hydrophila, Citrobacter, Klebsiella and Raoultella). I microrganismi identificati possono avere diverse origini, alcuni provengono dal terreno, altri possono essere comuni contaminanti delle acque ed altri avere un’origine antropica (batteri fecali). Fino a questo step del progetto, l’analisi PCR-DGGE ha evidenziato le evoluzioni ecologiche, in termine di popolazioni microbiche, presenti tra i diversi campioni e i diversi siti di campionamento all’interno di una stessa grotta.The Project Life + 08NAT/IT/000369 “Gypsum” 2, co-financed by the European Union, has started in the spring of 2010. This project aims to protect and manage the main karst caves and sites of Emilia-Romagna region. The A3 action provides a periodic monitoring of the main karst aquifers in terms of chemistry and microbiology. During the first year and a half, karst waters of 50 control points were analysed (sinking streams, rivers and streams in caves, and resurgences). The objective of this study is to evaluate the impact, in the waters of the cave, of agricultural substances or other forms of pollution or settlements related to human activities or natural factors. The experiment was developed using traditional microbiology techniques and molecular biology techniques (PCR and 16S rRNA PCR-DGGE), focused on the characterization of microbial populations in the different sampling sites and determination of their variations and/or changes. The total microbial concentration ranged from a maxiimum of 3.32 or 2.26 to values below the limit of detection (1 log CFU/ml) for total and faecal colifroms, respectively. The genetic analysis showed the presence of numerous bacterial species (Agrobacterium tumefaciens, Pseudomonas spp., Rahnella aquatilis, Stenotrophomonas maltophilia, Pedobacter swuonensis, Enterobacter spp., Aeromonas hydrophila, Citrobacter, Klebsiella and Raoultella). The organisms identified have different origins, some come from the ground, others are common water contaminants and others derive from human activities (faecal bacteria). Up to now, PCR-DGGE revealed the ecological changes, in terms of microbial populations present in the samples, and different sampling sites within the same cave

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