2,672 research outputs found

    Fingerprint Identification - New Directions

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    In most of the algorithms that have been suggested in this report, the fingerprint image is reduced to a relatively short sequence of integers. This reduces the memory size required by the database. Each algorithm is intended to exploit specific properties and features of the fingerprint that vary from finger to finger, and that can be localized relatively fast using digital techniques, thus also reducing the computational time requirements to a minimum. In each case, the sensitivity of the algorithm to small variations in the image was also discussed, with the aim of reducing the False Rejection Rate, and of increasing the general robustness of the algorithm

    The Blackhole-Dark Matter Halo Connection

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    We explore the connection between the central supermassive blackholes (SMBH) in galaxies and the dark matter halo through the relation between the masses of the SMBHs and the maximum circular velocities of the host galaxies, as well as the relationship between stellar velocity dispersion of the spheroidal component and the circular velocity. Our assumption here is that the circular velocity is a proxy for the mass of the dark matter halo. We rely on a heterogeneous sample containing galaxies of all types. The only requirement is that the galaxy has a direct measurement of the mass of its SMBH and a direct measurement of its circular velocity and its velocity dispersion. Previous studies have analyzed the connection between the SMBH and dark matter halo through the relationship between the circular velocity and the bulge velocity dispersion, with the assumption that the bulge velocity dispersion stands in for the mass of the SMBH, via the well{}-established SMBH mass{}-bulge velocity dispersion relation. Using intermediate relations may be misleading when one is studying them to decipher the active ingredients of galaxy formation and evolution. We believe that our approach will provide a more direct probe of the SMBH and the dark matter halo connection. We find that the correlation between the mass of supermassive blackholes and the circular velocities of the host galaxies is extremely weak, leading us to state the dark matter halo may not play a major role in regulating the blackhole growth in the present Universe.Comment: Accepted for publication in the Ap

    Cation Alloying as a Pathway to Reproducible olution Based Preparation of Efficient Metal Halide Perovskites Solar Cells with Increased Stability

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    With a certain amount of serendipity, research on dye sensitized solar cells led to the discovery of metal halide perovskite semiconductors as a solar energy conversion material1,2 that has inspired world wide research activities leading to efficiency increases from about 10 in 20123,4 to now 22 .5 8 Apart from their use as a single junction solar cell technology, metal halide perovskites can be processed as an add on layer onto other solar cells to realize efficient and low cost tandem architectures. The perovskite band gap can be tuned continuously from 1.1 to 3.0 eV by chemical engineering which makes them particularly relevant for multi junction devices.9 12 Experimental demonstrations of efficient tandem devices comprising metal halide perovskites as one13 15 or both10,16 components in a tandem stack highlight the potential for scalable and low cost multi junction devices17 with efficiencies approaching 30 is considered feasible.18,12,19,20 To reach this performance in a perovskite silicon tandem, the ideal band gap of the absorber material in top device should be about 1.7 eV18,12,21 sine silicon has a band gap of 1.1 eV .11,22,23 In this review, we dedicate section I to the discussion of the chemical tunability of metal halide perovskite with a particular focus on absorber materials with absorption onsets around 1.6 eV. Section II reflects on the benefit and role of including cesium Cs highlighting the work by Saliba et al.5,6 as this approach demonstrates a reliable pathway to obtain efficient solution processed metal halide perovskite absorbers with high reproducibility and extended operational device stability. Section III focuses on the state of the art of perovskite photovoltaics as a function of the absorption onset of the absorber layer highlighting materials with band gaps between 1.6 eV 1.75 eV as these are of great importance to the development of efficient tandem solar cells.12,18 20 In the conclusion section IV, we reflect on more general trends in metal halide alloys partially iscussed elsewhere23 highlighting cation alloying as an approach to obtain highly efficient devices in the band gap range between 1.6 and 1.7 eV. The data shown and discussed here is dominantly based on three of our recent publications and the interested reader is kindly referred to Unger et al.23 and Saliba et al.5,6 for more in depth discussions and experimental details

    Fourier Transform Holography: A Lensless Non-Destructive Imaging Technique

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    Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201

    Effect of EGF-Receptor Tyrosine Kinase Inhibitor on Rab5 Function During Endocytosis

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    Tyrosine autophosphorylation within the cytoplasmic tail of EGF-receptor is a key event, which in turn recruits several factors including Shc, Grb2 and Rin1 that are essential activities for receptor-mediated endocytosis and signaling. In this study, we demonstrated that treatment with AG1478, an EGF-receptor kinase inhibitor, blocked the formation of Rab5-positive endosomes as well as the activation of Rab5 upon addition of EGF. We also found that EGF-receptor catalytically inactive mutant failed to activate Rab5 upon EGF stimulation. Additionally, endosomal co-localization of Rab5 and EGF-receptor was inhibited by AG1478. Interestingly, AG1478 inhibitor did not block the formation of enlarged Rab5-positive endosomes in cells expressing Rab5 GTP hydrolysis defective mutant (Rab5:Q79L). AG1478 inhibitor also blocked the in vitroendosome fusion in a concentration-dependent manner, and more importantly, Rab5:Q79L mutant rescued it. Furthermore, addition of Rin1, a Rab5 guanine nucleotide exchange factor, partially restored endosome fusion in the presence of AG1478 inhibitor. Consistent with these observations, we also observed that Rin1 was unable to localize to membranes upon EGF-stimulation in the presence of AG1478 inhibitor. These results constitute first evidence that the enzymatic activity of a tyrosine kinase receptor is required endosome fusion via the activation of Rab5

    No Difference in Transverse Abdominis Activation Ratio between Healthy and Asymptomatic Low Back Pain Patients during Therapeutic Exercise

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    Dysfunction of the transverse abdominis (TrA) has been associated with LBP. Several therapeutic exercises are prescribed to help target the TrA. Rehabilitative ultrasound imaging (RUSI) is used to capture activation of the TrA during exercise. The purpose was to examine TrA activation during the ADIM and quadruped exercises between healthy and nonsymptomatic LBP patients. We instructed the subjects how to perform the exercises and measured muscle thickness of the TrA at rest and during the exercises using RUSI. This allowed us to calculate TrA activation ratio during these exercises. We found no significant differences between activation ratios of the two groups during either exercise; however TrA activation during the ADIM was higher than the quadruped exercise. These exercises were capable of activating the TrA, which may be in part due to the verbal instruction they received. These exercises could be used during prevention or rehabilitation programs, since the TrA is activated

    Design of a compact, dexterous robot hand with remotely located actuators and sensors

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    Abstract-In this work, we report on our progress in the development of a new anthropomorphic robot hand at the University of Malta. Following a brief overview of the work carried out in our laboratory so far, we discuss in some detail and through a fresh perspective a number of important lessons that can be learned from the human hand, and that can be very useful in the development of an artificial hand that can ultimately match the human counterpart in the execution of many tasks. We present a new design for a robot hand with joint position and grasping force sensing, based on the specific approaches brought up in this discussion, and targeted to reproduce many of the capabilities of the human hand. In particular, all of the actuation and sensing devices of the hand are located remotely from the device, therefore facilitating the development of a compact and lightweight hand design. A prototype of the new hand has been constructed and is presented herein. Finally, we present the initial results of our analysis to demonstrate how the magnitude and location of grasping forces can be inferred from the sensor readings

    Recognition and Assessment of Geomorphosites in Malta at the Il-Majjistral Nature and History Park

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    The Il-Majjistral Nature and History Park, located on the northwestern coast of the Island of Malta, is a protected area with natural, cultural and tourist interests. The Park, which was registered in 2008, is characterised by a landscape dominated by limestone and clay. Geomorphological features are highly controlled by the presence of faults and rock masses characterised by different physical and mechanical properties. Coastal cliffs, bays and sandy beaches are the most outstanding geomorphological features of the Park, creating a breathtaking landscape which is an attraction for a number of visitors. In the framework of an international research project, a study for the identification, selection and enhancement of the rich geomorphological heritage of the area has been carried out. In particular, a recognition and a quantitative assessment of geomorphosites on the basis of two different methodologies has been developed, and the results have been compared to establish the reliability of the methodologies. The results represent the first step and the necessary basic knowledge for possible enhancement of geomorphosites in Malta and the promotion of tourism activities at the Il-Majjistral Nature and History Park through the auspices of environmental agencies
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