1,721,065 research outputs found
InGaAs/InP SPAD with Monolithically Integrated Zinc-Diffused Resistor
No full textAfterpulsing and optical crosstalk are significant performance limitations for applications employing near-infrared single-photon avalanche diodes (SPADs). In this paper, we describe an InGaAs/InP SPAD with monolithically integrated resistor that is fully compatible with the planar fabrication process and provides a significant reduction of the avalanche charge and, thus, of afterpulsing and optical crosstalk. In order to have a fast SPAD reset (<50 ns), we fabricated quenching resistors ranging from 10 to 200 k\Ω, smaller than what is available in the literature. The resistor, fabricated with the zinc diffusions already used for avoiding premature edge-breakdown, promptly reduces the avalanche current to a low value ∼ 100~ μ A in less than 1 ns, while an active circuit completes the quenching and enforces a well-defined hold-off. The proposed mixed-quenching approach guarantees an avalanche charge reduction of more than 20 times compared with similar plain SPADs, enough to reduce the hold-off time down to 1 μ s. Finally, a compact single-photon counting module based on this detector and featuring 70-ps photon-timing jitter is presented
Tendon and ligament fibrillar crimps give rise to left-handed helices of collagen fibrils in both planar and helical crimps
No full textCollagen fibres in tendons and ligaments run straight but in some regions they show crimps which disappear or appear more flattened during the initial elongation of tissues. Each crimp is formed of collagen fibrils showing knots or fibrillar crimps at the crimp top angle. The present study analyzes by polarized light microscopy, scanning electron microscopy, transmission electron microscopy the 3D morphology of fibrillar crimp in tendons and ligaments of rat demonstrating that each fibril in the fibrillar region always twists leftwards changing the plane of running and sharply bends modifying the course on a new plane. The morphology of fibrillar crimp in stretched tendons fulfills the mechanical role of the fibrillar crimp acting as a particular knot/biological hinge in absorbing tension forces during fibril strengthening and recoiling collagen fibres when stretching is removed. The left-handed path of fibrils in the fibrillar crimp region gives rise to left-handed fibril helices observed both in isolated fibrils and sections of different tendons and ligaments (flexor digitorum profundus muscle tendon, Achilles tendon, tail tendon, patellar ligament and medial collateral ligament of the knee). The left-handed path of fibrils represents a new final suprafibrillar level of the alternating handedness which was previously described only from the molecular to the microfibrillar level. When the width of the twisting angle in the fibrillar crimp is nearly 180° the fibrils appear as left-handed flattened helices forming crimped collagen fibres previously described as planar crimps. When fibrils twist with different subsequent rotational angles (< 180°) they always assume a left-helical course but, running in many different nonplanar planes, they form wider helical crimped fibres. © 2010 The Authors. Journal compilation © 2010 Anatomical Society of Great Britain and Ireland
Histological and ultrastructural findings of gingival circular ligament surrounding osseointegrated non submerged loaded titanium implants
No full textInGaAs/InP single-photon detector gated at 1.3 GHz with 1.5% afterpulsing
Full text linkWe demonstrate a single-photon detector based on InGaAs/InP single-photon avalanche diodes (SPADs) sinusoidalgated at 1.3 GHz with very low afterpulsing (about 1.5%), high dynamic range (maximum count rate is 650 Mcount/s), high photon detection efficiency (>30% at 1550 nm), low noise (per-gate dark count rate is 2.2 x 10(-5)), and low timing jitter (<70 ps full-width at half-maximum). The SPAD is paired with a "dummy" structure that is biased in antiphase. The sinusoidal gating signals are cancelled by means of a common-cathode configuration and by adjusting the relative amplitude and phase of the signals biasing the two arms. This configuration allows us to adjust the gating frequency from 1 to 1.4 GHz and can be operated also in the so-called gate-free mode, with the gate sine-wave unlocked with respect to the light stimulus, resulting in a free-running equivalent operation of the InGaAs/InP SPAD with about 4% average photon detection efficiency at 1550 nm
Bone/HA-coated titanium implant interface. Histological and ultrastructural study in man
No full textMedicine and Life Sciences in Pavia and Bologna: History and Legacy (History of Science Exhibition, Tongji University, Shanghai, China, May 17-27, 2007; China Science and Technology Museum, Beijing, China, September 15-25, 2007)
No full textInterdisciplinary exhibition illustrating several fundamental steps in the history of medicine, biology and physics in Pavia and Bologna (14th-20th centuries), with a relevant number of original instruments, preparations and documents. The exhibition was first displayed in Shanghai (Tongji University, May 17-27, 2007) and subsequently in Beijing in the prestigious venue of the China Science and Technology Museum (September 15-25, 2007). The exhibition was the result of a joint effort of various institutions: the University of Pavia (Physics Department "A. Volta" and University Museums System), the IUSS-Pavia, the University of Bologna and the Tongji University (Shanghai). Under the patronage of the Italian Ministry of University and Research (MIUR), thousands of Chinese students and visitors had the opportunity to see and read in their own language about such a relevant part of Italy's scientific legacy.
The exhibition presented several significant steps in the development of natural history, medicine and physics at the Universities of Pavia and Bologna from the 14th to the 20th century.
The exhibition put a specific focus on the figures of Mondino de' Liuzzi (1270-1326: human dissection and teaching of anatomy), Marcantonio della Torre (1478-1511: anatomy and medicine), Gerolamo Cardano (1501-1576: medicine and mathematics), Gaspare Aselli (1580-1625: discovery of lymphatic vessels), Marcello Malpighi (1628-1694: the founder of microscopic anatomy), Antonio Maria Valsalva (1666-1723: anatomy of the ear), Giovan Battista Morgagni (1628-1771: the founder of pathological anatomy), Lazzaro Spallanzani (1729-1799: artificial fecundation and volcanology), Luigi Galvani (1737-1798: the discovery of animal electricity), Alessandro Volta (1745-1827: contact electricity and the invention of the battery), Antonio Scarpa (1752-1832: anatomy and surgery), Alessandro Codivilla (1861-1912: orthopaedic surgery), Camillo Golgi (1843-1926: neuroscience and cell biology)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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