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Intet resumé

Private Aggregation from Fewer Anonymous Messages

Consider the setup where $n$ parties are each given a number $x_i \in \mathbb{F}_q$ and the goal is to compute the sum $\sum_i x_i$ in a secure fashion and with as little communication as possible. We study this problem in the anonymized model of Ishai et al. (FOCS 2006) where each party may broadcast anonymous messages on an insecure channel. We present a new analysis of the one-round "split and mix" protocol of Ishai et al. In order to achieve the same security parameter, our analysis reduces the required number of messages by a $\Theta(\log n)$ multiplicative factor. We complement our positive result with lower bounds showing that the dependence of the number of messages on the domain size, the number of parties, and the security parameter is essentially tight. Using a reduction of Balle et al. (2019), our improved analysis of the protocol of Ishai et al. yields, in the same model, an $\left(\varepsilon, \delta\right)$-differentially private protocol for aggregation that, for any constant $\varepsilon > 0$ and any $\delta = \frac{1}{\mathrm{poly}(n)}$, incurs only a constant error and requires only a constant number of messages per party. Previously, such a protocol was known only for $\Omega(\log n)$ messages per party.Comment: 31 pages; 1 tabl

Discontinuous Transition from a Real Bound State to Virtual Bound State in a Mixed-Valence State of SmS

Golden SmS is a paramagnetic, mixed-valence system with a pseudogap. With increasing pressure across a critical pressure Pc, the system undergoes a discontinuous transition into a metallic, anti-ferromagnetically ordered state. By using a combination of thermodynamic, transport, and magnetic measurements, we show that the pseudogap results from the formation of a local bound state with spin singlet. We further argue that the transition Pc is regarded as a transition from an insulating electron-hole gas to a Kondo metal, i.e., from a spatially bound state to a Kondo virtually bound state between 4f and conduction electrons.Comment: 5 pages, 5 figure

Can Weakness in End-Range Plantar Flexion After Achilles Tendon Repair Be Prevented?

Background: Disproportionate end-range plantar flexion weakness, decreased passive stiffness, and inability to perform a heel rise on a decline after Achilles tendon repair are thought to reflect increased tendon compliance or tendon lengthening. Since this was first noted, we have performed stronger repairs and avoided stretching into dorsiflexion for the first 12 weeks after surgery. Hypothesis: Using stronger repairs and avoiding stretching into dorsiflexion would eliminate end-range plantar flexion weakness and normalize passive stiffness. Study Design: Case series; Level of evidence, 4. Methods: Achilles repairs with epitendinous augmentation were performed on 18 patients. Plantar flexion torque, dorsiflexion range of motion (ROM), passive joint stiffness, and standing single-legged heel rise on a decline were assessed at 43 ± 24 months after surgery (range, 9 months to 8 years). Maximum isometric plantar flexion torque was measured at 20° and 10° of dorsiflexion, neutral position, and 10° and 20° of plantar flexion. Passive dorsiflexion ROM was measured with a goniometer. Passive joint stiffness was computed from the increase in passive torque from 10° to 20° of dorsiflexion. Tendon thickness was measured by use of digital calipers. Plantar flexion electromyographic (EMG) data were recorded during strength and functional tests. Analysis of variance and chi-square tests were used to assess weakness and function. Results: Marked weakness was evident on the involved side at 20° of plantar flexion (deficit, 26% ± 18%; Conclusion: The use of stronger repair techniques and attempts to limit tendon elongation by avoiding dorsiflexion stretching did not eliminate weakness in end-range plantar flexion. EMG data confirmed that end-range weakness was not due to neural inhibition. Physiological changes that alter the force transmission capability of the healing tendon may be responsible for this continued impairment. This weakness has implications for high-demand jumping and sprinting after Achilles tendon repair

Structure-Based Discovery of Dual-Target Hits for Acetylcholinesterase and the α7 Nicotinic Acetylcholine Receptors: In Silico Studies and In Vitro Confirmation

Publisher's version (útgefin grein)Despite extensive efforts in the development of drugs for complex neurodegenerative diseases, treatment often remains challenging or ineffective, and hence new treatment strategies are necessary. One approach is the design of multi-target drugs, which can potentially address the complex nature of disorders such as Alzheimer’s disease. We report a method for high throughput virtual screening aimed at identifying new dual target hit molecules. One of the identified hits, N,N-dimethyl-1-(4-(3-methyl-[1,2,4]triazolo[4,3-a]pyrimidin-6-yl)phenyl)ethan-1-amine (Ýmir-2), has dual-activity as an acetylcholinesterase (AChE) inhibitor and as an α7 nicotinic acetylcholine receptor (α7 nAChR) agonist. Using computational chemistry methods, parallel and independent screening of a virtual compound library consisting of 3,848,234 drug-like and commercially available molecules from the ZINC15 database, resulted in an intersecting set of 57 compounds, that potentially possess activity at both of the two protein targets. Based on ligand efficiency as well as scaffold and molecular diversity, 16 of these compounds were purchased for in vitro validation by Ellman’s method and two-electrode voltage-clamp electrophysiology. Ýmir-2 was shown to exhibit the desired activity profile (AChE IC50 = 2.58 ± 0.96 µM; α7 nAChR activation = 7.0 ± 0.9% at 200 µM) making it the first reported compound with this particular profile and providing further evidence of the feasibility of in silico methods for the identification of novel multi-target hit molecules.This research was supported by the Icelandic Centre for Research [grant number: 152604], doctoral grant and financial support from the University of Iceland.Peer Reviewe

Frozen spatial chaos induced by boundaries

We show that rather simple but non-trivial boundary conditions could induce the appearance of spatial chaos (that is stationary, stable, but spatially disordered configurations) in extended dynamical systems with very simple dynamics. We exemplify the phenomenon with a nonlinear reaction-diffusion equation in a two-dimensional undulated domain. Concepts from the theory of dynamical systems, and a transverse-single-mode approximation are used to describe the spatially chaotic structures.Comment: 9 pages, 6 figures, submitted for publication; for related work visit http://www.imedea.uib.es/~victo

Vectorial dissipative solitons in vertical-cavity surface-emitting Lasers with delays

We show that the nonlinear polarization dynamics of a vertical-cavity surface-emitting laser placed into an external cavity leads to the formation of temporal vectorial dissipative solitons. These solitons arise as cycles in the polarization orientation, leaving the total intensity constant. When the cavity round-trip is much longer than their duration, several independent solitons as well as bound states (molecules) may be hosted in the cavity. All these solutions coexist together and with the background solution, i.e. the solution with zero soliton. The theoretical proof of localization is given by the analysis of the Floquet exponents. Finally, we reduce the dynamics to a single delayed equation for the polarization orientation allowing interpreting the vectorial solitons as polarization kinks.Comment: quasi final resubmission version, 12 pages, 9 figure

Global trends in environmental management system and ISO14001 research

The International Organisation for Standardization (ISO) 14001 Environmental Management System (EMS) standard provides a guideline for an organisation to perform a continuous improvement to their environmental performance. In light of continued concerns over global environmental impacts and climate change, the ISO 14001 standard serves to demonstrate organisational commitment to sustainable production processes. The objective of our paper is to determine the thematic and geographical trends of published EMS research with a view of developing a coordinated and holistic research framework which can be applied to facilitate the adoption of ISO 14001 in developing and developed regions of the world. Drawn from a portfolio of 509 articles from the Web of Science database, this study investigates the global trends of ISO 14001 EMS research between 2000 and 2016. The results show a considerable increase in scientific publications; from 10 articles in 2000 to 58 articles in 2016. Three themes were identified from the analysis: socio-ecological (60%), economic implications (25%), and environmental aspects (15%). In addition to a concentration of articles towards the socio-ecological theme of research, it is found that the majority of the published research derived from Europe (40%), North America (21%), and China (11%). Articles authored by researchers from developing countries were poorly represented in the findings. In order to address the thematic and global imbalance of EMS research, a research framework is proposed that promotes multi-stakeholders inclusion (e.g. industry, academics, government, etc.), cross-country research collaboration and a focus on demand-driven approach for problem solving and policy-making

Visiting the iron cage: Bureaucracy and the contemporary workplace

Bureaucracy as an organizational form has always been a controversial issue and placed at the very heart of most discussions within organizational theory. One side of this prolonged discussion praises this administrative form as the ‘rational’ way to run an organization. It provides needed guidance and clarifies responsibilities, which enables employees to become more efficient. However, the opposition claims that in a non-linear world, where industrial organizations are forced to confront the challenging task of sensing and responding to unpredictable, novel situations of highly competitive markets, such an organizational form stifles creativity, fosters de-motivation and causes pressure on employees. Dealing with a bureaucratic form of organization and its consequences begs for a context. It would be appropriate to quit ‘taking sides’ and develop a sound analysis of this phenomenon under the conditions of today’s global workplace environment. This chapter intends to delineate the conditions under which bureaucracy has emerged and the way it has been interpreted since its inception and develop a sound and appropriate analytical approach to its functioning given the prevailing conditions of the contemporary workplace.Publisher's VersionAuthor Post Prin