Round-Optimal Secure Two-Party Computation from Trapdoor Permutations

In this work we continue the study on the round complexity of secure two-party computation with black-box simulation. Katz and Ostrovsky in CRYPTO 2004 showed a 5 (optimal) round construction assuming trapdoor permutations for the general case where both players receive the output. They also proved that their result is round optimal. This lower bound has been recently revisited by Garg et al. in Eurocrypt 2016 where a 4 (optimal) round protocol is showed assuming a simultaneous message exchange channel. Unfortunately there is no instantiation of the protocol of Garg et al. under standard polynomial-time hardness assumptions. In this work we close the above gap by showing a 4 (optimal) round construction for secure two-party computation in the simultaneous message channel model with black-box simulation, assuming trapdoor permutations against polynomial-time adversaries. Our construction for secure two-party computation relies on a special 4-round protocol for oblivious transfer that nicely composes with other protocols in parallel. We define and construct such special oblivious transfer protocol from trapdoor permutations. This building block is clearly interesting on its own. Our construction also makes use of a recent advance on non-malleability: a delayed-input 4-round non-malleable zero knowledge argument

Shape and Charge: Faraday's Ice Pail Experiment Revisited

Electrically insulating objects gain a net electrical charge when brought in and out of contact. This phenomenon, known as triboelectrification, is very common and familiar to many of us from a car static zap, to the danger of ignition for hydrocarbons flowing through poorly grounded pipes, to the transfer of inks in a xerographic device. Despite our familiarity with triboelectrification, we still do not have a complete chemical picture of its origin,(1−4) and the exact mechanism by which objects that do not conduct electricity gain an electric charge remains a long-standing scientific puzzle.(4−6) In this issue of ACS Central Science, Soh and co-workers explore another aspect of this phenomenon: the relationship between static charge and the shape of the objects.(7

Device for vitrectomy surgical operations

A vitrectomy probe for removing vitreous material from an eyeball, having a longitudinal axis and an outer tube with a closed end and a lateral surface, at least one inlet port located proximate to the closed end and configured to allow the vitreous material to enter into the outer tube; an inner tube arranged in the outer tube to relatively move with respect to the outer tube, the inner tube having an opening with a cutting profile through which the vitreous material can be cut and can enter the inner tube, a drive unit configured for causing the outer tube and the inner tube to move relatively with respect to each other, in such a way that the cutting profile cuts the vitreous material entering the inlet port

Escuela, en Daly-City-California

El arquitecto de hoy tiene una gran responsabilidad, no sólo para resolver en el plano técnico todas las consideraciones de forma y material que plantea el proyecto de una escuela de enseñanza media, sino también para considerar los problemas psicológicos y filosóficos de la misma. Estos problemas obligan al arquitecto a empezar su proyecto desde el punto de vista fundamental de crear un ambiente adecuado para la enseñanza. Este ambiente a crear debe responder no sólo a las exigencias presentes, sino que tiene que anticiparse al desarrollo cultural futuro. La escuela debe ser como una fuerza motriz que ofrece al estudiante la oportunidad para su educación

Spatially-resolved magnetic resonance study of the dissolution interface between soaps and water

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Direct-current output of silicon–organic monolayer–platinum Schottky TENGs: Elusive friction-output relationship

Triboelectric nanogenerators (TENGs) are an emerging energy harvesting technology able to convert ubiquitous mechanical energy into electricity. Friction, static charging and flexoelectricity are all involved in the mechanism underpinning TENG operation, but their relative contribution has remained elusive. Here we used dynamic and static conductive atomic force microscopy (C-AFM) measurements on monolayer-modified silicon crystals to detect evidence of a relationship between friction and zero-bias current, and between pressure and the direction of the putative flexovoltage. We demonstrate that a static electricity-related tribovoltage is probably responsible for a friction excess, and that surprisingly this friction excess is found to be dependent on the doping level and type of the silicon substrate. Such friction excess is however no longer measurable once current is allowed to flow across the junction. This observation points to an electrostatic origin of friction in silicon-based Schottky TENGs, and suggests that the zero external bias DC current is at least in part an electronic flow to neutralize static charges. Further, the sign of the zero-bias current, but not its magnitude, is independent of the semiconductor doping type, which is again suggestive of surface statics being a main contributor to the zero-bias output rather than exclusively a space-charge effect. We also reveal the presence of a junction flexovoltage under pressures common in AFM experiments (GPa), even for negligible lateral friction. In a static Pt–monolayer–n-type Si junction the flexovoltage carries the same sign as the tribovoltage, and can reach such magnitude to overwrite external voltages as high as 2 V. The immediate implication is that the flexovoltage is likely to have i) a strong contribution to the zero-bias output of a n-Si Schottky TENG, ii) a negative effect on the output of a p-Si TENG, and iii) its detection can be straightforward, as we discovered that flexoelectricity manifests as an “inverted diode”: a n-type Si–platinum diode with negligible current even when the n-type material is negatively biased as long as the “static” diode remains under a large normal pressure

Safety and effectiveness of a new electrical detachable microcoil for embolization of hemorrhoidal disease, November 2020–December 2021: results of a prospective study

Purpose: The purpose of this study was to prospectively evaluate the efficacy and safety of a new, bare platinum, detachable microcoil as a metallic embolization agent in the treatment of hemorrhoidal disease. Material and Methods: This prospective single-center study evaluated a new, bare platinum, electrical, detachable microcoil (Prestige plus coil (Balt Montmorency France)) for use in vascular embolization in patients with hemorrhoidal disease. Between January 2020 and January 2021, 24 embolization procedures were performed in 21 patients (12 males, 9 females; mean age 44.3 ± 7.3). The inclusion criteria were: (a) participants with grade I, II and III hemorrhoidal disease on the Goligher classification; (b) patients older than 18 years of age with a score of greater than 4 on the French bleeding score (FBS) scale; (c) patients with scores greater than 2 on the scale of discomfort proposed by Tradi and Farfallah. (d) patients who underwent treatment that included the use of the new novel coil (Prestige plus coil (Balt)) as an embolic material. The exclusion criteria were participants who failed to provide informed consent and participants diagnosed with rectal bleeding due to other causes (cancer, fissures or others). Participants with severe renal insufficiency, non-correctable coagulation abnormalities and adverse reactions to the contrast medium not correctable with medication were also excluded. The symptoms, technical aspects, the transarterial approach, clinical and technical success complications and short-term outcomes were assessed. Results: Technical success was obtained in 100% of the cases. Seventeen (80.9%) patients experienced improvements in their hemorrhoidal disease. The VAS and QL scores improved by 4 and 1.5 points (81.2% and 87.5%), respectively, after embolization (pV: 0001). Three (14.2%) patients underwent a second embolization due to rebleeding. One patient (4.7%) underwent surgery. No major complications were observed. Three patients had minor complications. The assessment of subjective post-treatment symptoms and QL surveys showed significant differences from the baseline survey. Likewise, the measurement of the degree of satisfaction using a telephone survey at 12 months revealed a high degree of patient satisfaction over 10 points (mean 8.3 ± 1.1). Conclusions: The present study demonstrates that the use of the new, platinum, detachable, electrical microcoil is safe and well-tolerated in the treatment of hemorrhoidal disease. Key points: Catheter-directed hemorrhoidal dearterialization (CDHD) is the procedure of embolization with embolic agents for the treatment of internal hemorrhoids. CDHD is a simple and safe procedure that is accepted by patients and preserves the anal sphincter; it presents few complications when metal devices or microspheres are used as embolic agents. As the recommended embolization agent in treatments, the Prestige electrical, detachable coil is a safe, easy-to-use and effective arterial embolic device

Single-molecule electrical contacts on silicon electrodes under ambient conditions

The ultimate goal in molecular electronics is to use individual molecules as the active electronic component of a real-world sturdy device. For this concept to become reality, it will require the field of single-molecule electronics to shift towards the semiconducting platform of the current microelectronics industry. Here, we report silicon-based single-molecule contacts that are mechanically and electrically stable under ambient conditions. The single-molecule contacts are prepared on silicon electrodes using the scanning tunnelling microscopy break-junction approach using a top metallic probe. The molecular wires show remarkable current–voltage reproducibility, as compared to an open silicon/nano-gap/metal junction, with current rectification ratios exceeding 4,000 when a low-doped silicon is used. The extension of the single-molecule junction approach to a silicon substrate contributes to the next level of miniaturization of electronic components and it is anticipated it will pave the way to a new class of robust single-molecule circuits