1,721,035 research outputs found
Shared and Searchable Encrypted Data for Untrusted Servers
No full textCurrent security mechanisms pose a risk for organisations that outsource their data management to untrusted servers. Encrypting and decrypting sensitive data at the client side is the normal approach in this situation but has high communication and computation overheads if only a subset of the data is required, for example, selecting records in a database table based on a keyword search. New cryptographic schemes have been proposed that support encrypted queries over encrypted data but all depend on a single set of secret keys, which implies single user access or sharing keys among multiple users, with key revocation requiring costly data re-encryption. In this paper, we propose an encryption scheme where each authorised user in the system has his own keys to encrypt and decrypt data. The scheme supports keyword search which enables the server to return only the encrypted data that satisfies an encrypted query without decrypting it. We provide two constructions of the scheme giving formal proofs of their security. We also report on the results of a prototype implementation
TinyKey: A light-weight architecture for wireless sensor networks securing real-world applications
No full textWhile sharing some commonalities with a canonical computer network, Wireless Sensor Network (WSN) presents many aspects which are unique. Security mechanisms in a WSN are mainly devoted to protect both the resources from attacks and misbehavior of nodes and the information transferred throughout the network itself. While the vast majority of the works on security for WSN in literature are focusing on novel mechanisms or performance evaluation in “protected” environment like simulators or dedicated WSN testbeds, to the best of our knowledge there are no existing works describing the performance of security mechanisms in operational WSN dealing with real-world applications. In this paper, we present TinyKey, a security architecture for WSNs that takes into account pragmatic concerns of a real-work deployment. For instance, most of the approaches in literature have neglected mechanisms related to key management. TinyKey comes with an integrated key management system that can be used in any deployment. We have developed TinyKey to satisfy the security requirements of two projects funded by the local government of the Trento province in Italy that aim at developing and deploying real-world applications based on WSNs. One project aims at improving the safety of the road tunnels around the city of Trento while the second project focuses on improving the quality of life of elderly people. As a result, we have been able to measure the performances of TinyKey in real deployments
Two-Dimensional and Doppler Echocardiographic findings in healthy non-sedated red-eared slider terrapins (Trachemys scripta elegans)
No full textEchocardiographic evaluation was performed in six healthy young adult non-sedated terrapins (Trachemys scripta elegans). The best imaging quality was obtained through the right cervical window. Base-apex inflow and outflow views were recorded, ventricular size, ventricular wall thickness and ventricular outflow tract were measured, and fractional shortening was calculated. Pulsed-wave Doppler interrogation enabled the diastolic biphasic atrio-ventricular flow and the systolic ventricular outflow patterns to be recorded. The following Doppler-derived functional parameters were calculated: early diastolic (E) and late diastolic (A) wave peak velocities, E/A ratio, ventricular outflow systolic peak and mean velocities and gradients, Velocity-Time Integral, acceleration and deceleration times, and Ejection Time. For each parameter the mean, standard deviation and 95% confidence interval were calculated. Echocardiography resulted as a useful and easy-to-perform diagnostic tool in this poorly known species that presents difficulties during evaluation
Interface infectious keratitis after anterior and posterior lamellar keratoplasty. Clinical features and treatment strategies. A review
No full textInterface infectious keratitis (IIK) is a novel corneal infection that may develop after any type of lamellar keratoplasty. Onset of infection occurs in the virtual space between the graft and the host where it may remain localised until spreading with possible risk of endophthalmitis. A literature review identified 42 cases of IIK. Thirty-one of them occurred after endothelial keratoplasty and 12 after deep anterior lamellar keratoplasty. Fungi in the form of Candida species were the most common microorganisms involved, with donor to host transmission of infection documented in the majority of cases. Donor rim cultures were useful to address the infectious microorganisms within few days after surgery. Due to the sequestered site of infection, medical treatment, using both topical and systemic antimicrobials drugs, was ineffective on halting the progression of the infection. Injection of antifungals, right at the graft-host interface, was reported successful in some cases. Spreading of the infection with development of endophthalmitis occurred in five cases after Descemet stripping automated endothelial keratoplasty with severe sight loss in three cases. Early excisional penetrating keratoplasty showed to be the treatment with the highest therapeutic efficacy, lowest rate of complications and greater visual outcomes
Diagnostic approach and epidemiology of Microbial Keratitis: findings from an Italian Tertiary Care center
Full text linkRapid identification of causative microorganisms of microbial keratitis (MK) and knowledge of the most common local pathogens are prerequisites for rational antimicrobial therapy. We retrospectively reviewed the characteristics of MK diagnosed at the IRCCS Arcispedale Santa Maria Nuova of Reggio Emilia (Italy) in a 5-years period, where the Ophthalmologist Unit is a reference center for corneal infections. During the study period, 183 MK were evaluated through corneal scrapings cultures. The positivity rate was 54,1%. A total of 107 microorganisms have been isolated: Acanthamoeba species was the etiologic agent in 19 cases. Pseudomonas aeruginosa and Staphylococcus aureus were more frequently isolated in bacterial keratitis, while Fusarium spp., Candida albicans, and Alternaria alternata were predominant among the fungal isolates. Strict cooperation between ophthalmologists and clinical microbiologists is advisable to allow the best diagnostic approach for MK
Excisional penetrating keratoplasty for fungal interface keratitis after endothelial keratoplasty: surgical timing and visual outcome
No full texturpose: In this paper, we describe two cases of fungal interface infectious keratitis (IIK) developed after endothelial keratoplasty (EK) who underwent delayed therapeutic penetrating keratoplasty (TPK) with a poor visual outcome. Furthermore, we conducted a review of the literature and analyzed the visual outcomes of TPK in relation to the time from IIK diagnosis.
Methods: We searched the literature for fungal IIK cases occurred after EK and treated by TPK. We identified 17 cases of fungal IIK, mostly caused by Candida spp. (88%).
Results: Infection was diagnosed at a median time of 21 (range 1-90 days) days after EK. The median lag time between infection diagnosis and TPK was 30 (range 7-393) days. The median distance corrected visual acuity (DCVA) measured 4-12 months after surgery was 20/40 (range 20/200-20/20). When TPK was performed within one month from diagnosis, the final median DCVA was 20/30 (range 20/100-20/20), with 83% of patients achieving ≥ 20/40 vision. When TPK was carried out later, the final median DCVA was 20/50 (range 20/200-20/22) with 44% of patients achieving ≥ 20/40 vision. One patient in the early surgery and four patients in the late surgery group showed postoperative DCVA ≤ 20/100 despite clear grafts.
Conclusion: TPK with removal of the sequestered infection is advocated as a safe and effective measure to treat a post-EK infection. Early surgery allows a reduced exposure time to infection and therefore may result in better visual outcomes and lower risk of complications caused by prolonged inflammation
Emergency access control management via attribute based encrypted QR codes
No full textIn dynamic environments such as disaster management, mechanisms for the controlled override of access restrictions, a.k.a. break-glass need to be supported. These access control mechanisms should ensure access to facilities, for example, an office building, in an emergency situation, without relying on the use of an online authentication server as connectivity might not be available. In this paper, we propose a break-glass access control mechanism based on a novel use of QR codes, Shamir's Secret Sharing Scheme and Attribute Based Encryption. Our proposed solution is such that a secret access key is split using Shamir's secret sharing scheme and encrypted using attribute based encryption, then encoded in a QR code. Subsequently, emergency actors scan the QR code and recover the individual secret key using their attributes satisfying an access policy associated with the ciphertext. The novelty of our solution lies in the fact that a flexible access control is ensured only when a sufficient number of authorized users collaborate to get access to a building without requiring an online third party. In addition, the access secret key is only decrypted by the authorized users thanks to the use of an attribute based encryption scheme. Finally, we demonstrate the feasibility and the efficiency of the solution by implementing a prototype and analysing its performance
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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