Discrete soliton ratchets driven by biharmonic fields

Directed motion of topological solitons (kinks or antikinks) in the damped and AC-driven discrete sine-Gordon system is investigated. We show that if the driving field breaks certain time-space symmetries, the soliton can perform unidirectional motion. The phenomenon resembles the well known effects of ratchet transport and nonlinear harmonic mixing. Direction of the motion and its velocity depends on the shape of the AC drive. Necessary conditions for the occurrence of the effect are formulated. In comparison with the previously studied continuum case, the discrete case shows a number of new features: non-zero depinning threshold for the driving amplitude, locking to the rational fractions of the driving frequency, and diffusive ratchet motion in the case of weak intersite coupling.Comment: 13 pages, 13 figure

Novel Computing Paradigms using Oscillators

This dissertation is concerned with new ways of using oscillators to perform computational tasks. Specifically, it introduces methods for building finite state machines (for general-purpose Boolean computation) as well as Ising machines (for solving combinatorial optimization problems) using coupled oscillator networks.But firstly, why oscillators? Why use them for computation?An important reason is simply that oscillators are fascinating. Coupled oscillator systems often display intriguing synchronization phenomena where spontaneous patterns arise. From the synchronous flashing of fireflies to Huygens' clocks ticking in unison, from the molecular mechanism of circadian rhythms to the phase patterns in oscillatory neural circuits, the observation and study of synchronization in coupled oscillators has a long and rich history. Engineers across many disciplines have also taken inspiration from these phenomena, e.g., to design high-performance radio frequency communication circuits and optical lasers. To be able to contribute to the study of coupled oscillators and leverage them in novel paradigms of computing is without question an interesting andfulfilling quest in and of itself.Moreover, as Moore's Law nears its limits, new computing paradigms that are different from mere conventional complementary metal–oxide–semiconductor (CMOS) scaling have become an important area of exploration. One broad direction aims to improve CMOS performance using device technology such as fin field-effect transistors (FinFET) and gate-all-around (GAA) FETs. Other new computing schemes are based on non-CMOS material and device technology, e.g., graphene, carbon nanotubes, memristive devices, optical devices, etc.. Another growing trend in both academia and industry is to build digital application-specific integrated circuits (ASIC) suitable for speeding up certain computational tasks, often leveraging the parallel nature of unconventional non-von Neumann architectures. These schemes seek to circumvent the limitations posed at the device level through innovations at the system/architecture level.Our work on oscillator-based computation represents a direction that is different from the above and features several points of novelty and attractiveness. Firstly, it makes meaningful use of nonlinear dynamical phenomena to tackle well-defined computational tasks that span analog and digital domains. It also differs from conventional computational systems at the fundamental logic encoding level, using timing/phase of oscillation as opposed to voltage levels to represent logic values. These differences bring about several advantages. The change of logic encoding scheme has several device- and system-level benefits related to noise immunity and interference resistance. The use of nonlinear oscillator dynamics allows our systems to address problems difficult for conventional digital computation. Furthermore, our schemes are amenable to realizations using almost all types of oscillators, allowing a wide variety of devices from multiple physical domains to serve as the substrate for computing. This ability to leverage emerging multiphysics devices need not put off the realization of our ideas far into the future. Instead, implementations using well-established circuit technology are already both practical and attractive.This work also differs from all past work on oscillator-based computing, which mostly focuses on specialized image preprocessing tasks, such as edge detection, image segmentation and pattern recognition. Perhaps its most unique feature is that our systems use transitions between analog and digital modes of operation --- unlike other existing schemes that simply couple oscillators and let their phases settle to a continuum of values, we use a special type of injection locking to make each oscillator settle to one of the several well-defined multistable phase-locked states, which we use to encode logic values for computation. Our schemes of oscillator-based Boolean and Ising computation are built upon this digitization of phase; they expand the scope of oscillator-based computing significantly.Our ideas are built on years of past research in the modelling, simulation and analysis of oscillators. While there is a considerable amount of literature (arguably since Christiaan Huygens wrote about his observation of synchronized pendulum clocks in the 17th century) analyzing the synchronization phenomenon from different perspectives at different levels, we have been able to further develop the theory of injection locking, connecting the dots to find a path of analysis that starts from the low-level differential equations of individual oscillators and arrives at phase-based models and energy landscapes of coupled oscillator systems. This theoretical scaffolding is able not only to explain the operation of oscillator-based systems, but also to serve as the basis for simulation and design tools. Building on this, we explore the practical design of our proposed systems, demonstrate working prototypes, as well as develop the techniques, tools and methodologies essential for the process

The Battle Against Geo-Blocking: The Consumer Strikes Back

The first part of this article will focus on the background of copyright law and its expansion in the digital age. The development of copyright law in the United States will be discussed along with a focus on current case law that has applied copyright law to the Internet and advancing technologies. Part I will also look into the expansion of copyright protection to an international level, including the creation of WIPO and the WIPO Copyright Treaty. Finally, Part I will discuss the popular trend of how consumers use the Internet to access digital copyrightable material. The second part of this article will focus on one hand how television networks (Networks), as copyright holders, use the rising popularity of Internet streaming to their benefit. Alternatively, it will also focus on how these Networks also hinder themselves in the precautions that they set forth, such as region locking (also called geo-blocking ) and delayed viewing for certain areas of the world. Due to the precautions used, this part will also highlight how these methods hurt, rather than help, these copyright holders. This section will discuss arguments for and against geo-blocking. Additionally, the section will consider the legality and rationality of geo-blocking and the use of circumvention measures. Finally, the third part of this article will discuss how the Industry should change to keep up with social change. Industry change would achieve two main goals. The first goal is to keep up to date with changing technology and the way that people use the Internet. The second goal is to reduce the amount of piracy that occurs. This will in turn help copyright holders reclaim lost profits in both advertisement revenue and the purchasing of television programs. This section will also discuss how some of this change is already occurring with international organizations

Coupled normal fluid and superfluid profiles of turbulent helium II in channels

We perform fully coupled two--dimensional numerical simulations of plane channel helium II counterflows with vortex--line density typical of experiments. The main features of our approach are the inclusion of the back reaction of the superfluid vortices on the normal fluid and the presence of solid boundaries. Despite the reduced dimensionality, our model is realistic enough to reproduce vortex density distributions across the channel recently calculated in three--dimensions. We focus on the coarse--grained superfluid and normal fluid velocity profiles, recovering the normal fluid profile recently observed employing a technique based on laser--induced fluorescence of metastable helium molecules.Comment: 26 pages, 8 Figures, accepted for publication in Phys. Rev.

Addressing telecommuting in cyber security guidelines

Cyber security threats are becoming more common than before. New phenomena in society include new cyber security threats which organisations and society should prepare for. One of these phenomena is telecommuting. Telecommuting has its roots already in the 1970s, but it has become increasingly popular during the last years. Especially the pandemic caused by Covid-19 has changed the way of working drastically. Pandemic and the social distancing forced many organisations to have their employees working from home. Information technology has abled telecommuting, but it has also brought some problems such as security issues. Cyber security threats have increased and become more diverse during the mass telecommuting caused by Covid-19. Telecommuting has some special features that can increase cyber security threats and risks. In this research the following cyber security threats relating to telecommuting were identified to be most relevant: cyber attacks, social engineering, unauthorized access and physical security. Previous literature has identified that there exist cyber security threats in telecommuting, but it has remained unclear how organisations manage and mitigate these in practice. Many of the identified threats relate to employees’ unwanted behaviour. Employees are unaware of the threats facing the organisation in telecommuting. Some employees have not been provided with proper guidelines and instruction on secure way of working. Information security policies and guidelines are important for maintaining cyber security in organisations. Policies can be even seen as the basis for organisation’s cyber security. This research studied which guidelines could be applicable in a telecommuting environment in order to mitigate the common cyber security threats. Most prominent cyber security guidelines for telecommuting identified in this research were guidelines for personal and mobile devices, guidelines for social engineering, guidelines for physical security, network guidelines, password guidelines and guidelines for online meetings. Case study of multiple cases was used as a method for this study. The cases are seven Finnish universities. The empirical data consists of cyber security and telecommuting guidelines from the universities. These guidelines were analysed by reflecting to the theoretical framework. The analysis showed that especially guidelines for physical security and online meetings were lacking. The presence of outsiders in the telecommuting environment was addressed poorly. Outsiders are a threat both to physical and online meeting security as outsiders may see or hear confidential things. In addition, guidelines were not addressing data labelling and information release. Threats specific to Covid-19 were also addressed poorly even though cyber criminals have exploited the pandemic. Guidelines seemed to be otherwise comprehensive. Threats that were addressed poorly have been especially relevant during the pandemic which suggests that organisations’ guidelines are not quite up to date even though otherwise applicable. Organisations should review and update their guidelines periodically and if a major change occurs in the operation environment.Kyberturvallisuusuhat ovat yleistymässä. Uudet ilmiöt tuovat mukanaan uusia kyberturvallisuusuhkia, joihin organisaatioiden ja yhteiskunnan tulee varautua. Yksi näistä ilmiöistä on etätyö. Etätyön juuret ovat jo 1970-luvulla, mutta sen suosio on kasvanut viime vuosina. Erityisesti Covid-19 ja sen aiheuttama pandemia ovat muuttaneet työn toimintatapoja radikaalisti, sillä pandemia pakotti monet työntekijät etätyöhön. Tietotekniikka on mahdollistanut etätyön, mutta se on tuonut myös ongelmia liittyen kyberturvaan. Kyberturvallisuusuhat ovat lisääntyneet ja monipuolistuneet pandemian aiheuttaman laajalle levinneen etätyön myötä. Etätyössä on joitain erityispiirteitä, jotka voivat lisätä kyberturvallisuusuhkia ja -riskejä perinteiseen työntekoon verraten. Tässä tutkimuksessa tärkeimmiksi etätyöhön liittyviksi kyberuhiksi tunnistettiin kyberhyökkäykset, sosiaalinen manipulointi, valtuuttamaton pääsy ja huono fyysinen turvallisuus. Aikaisemmassa kirjallisuudessa on havaittu, että etätyöhön liittyy kyberturvallisuusuhkia, mutta on jäänyt epäselväksi, miten organisaatiot hallitsevat ja vähentävät niitä käytännössä. Monet tunnistetuista uhista liittyvät työntekijöiden ei-toivottuun käyttäytymiseen. Työntekijät eivät välttämättä ole tietoisia etätyön uhista organisaatiolle. Osalle työntekijöistä ei ole myöskään annettu asianmukaisia ohjeita kyberturvallisista työskentelytavoista. Tietoturvapolitiikat ja - ohjeet ovat tärkeitä organisaatioiden kyberturvallisuuden ylläpitämisessä. Politiikkoja voidaan pitää jopa organisaation kyberturvallisuuden perustana. Tässä tutkimuksessa selvitettiin, minkälaisia ohjeita tarvitaan etätyössä yleisten kyberturvallisuusuhkien lieventämiseksi. Tässä tutkimuksessa tunnistetut kyberturvallisuusohjeet etätyöhön liittyivät henkilökohtaisten ja mobiililaitteiden käyttöön, sosiaaliseen manipulointiin, fyysiseen turvallisuuteen, turvattomiin verkkoihin, salasanoihin ja online-kokouksiin. Tutkimusmetodina tässä tutkimuksessa käytettiin usean tapauksen tapaustutkimusta. Tapauksina toimivat seitsemän suomalaista yliopistoa. Empiirinen data koostuu Suomessa toimivien yliopistojen kyberturvallisuus- ja etätyöohjeista. Nämä ohjeet analysoitiin teoreettiseen viitekehyksen avulla ja siihen viitaten. Analyysi osoitti, että erityisesti fyysistä turvallisuutta ja online-kokouksia koskevat ohjeet ovat puutteellisia. Ulkopuolisten läsnäolo etätyöympäristössä on huomioitu huonosti. Ulkopuoliset ovat uhka sekä fyysiselle että online-kokousten turvallisuudelle, koska ulkopuoliset voivat nähdä tai kuulla luottamuksellisia asioita. Lisäksi datan merkitsemiseen ja tiedon jakamiseen liittyvät ohjeet puuttuivat. Covid-19 oli myös huomioitu huonosti, vaikka pandemian aikana on ollut useita kyberhyökkäyksiä, jotka ovat hyödyntäneet Covid-19 tuomaa epävarmuutta. Yliopistojen ohjeet näyttivät muuten olevan kattavat. Huonosti huomioon otetut ohjeet ovat sellaisia, jotka ovat olleet esillä etenkin pandemian aikana. Vaikuttaa siltä, että organisaatioiden ohjeet eivät ole täysin ajan tasalla, vaikka ne muuten olisivat tarkoituksenmukaiset. Organisaatioiden tuleekin tarkistaa ja päivittää ohjeitaan säännöllisesti ja aina, jos toimintaympäristössä tapahtuu suuria muutoksia

Analyzing confidentiality and privacy concerns: insights from Android issue logs

Context: Post-release user feedback plays an integral role in improving software quality and informing new features. Given its growing importance, feedback concerning security enhancements is particularly noteworthy. In considering the rapid uptake of Android we have examined the scale and severity of Android security threats as reported by its stakeholders. Objective: We systematically mine Android issue logs to derive insights into stakeholder perceptions and experiences in relation to certain Android security issues. Method: We employed contextual analysis techniques to study issues raised regarding confidentiality and privacy in the last three major Android releases, considering covariance of stakeholder comments, and the level of consistency in user preferences and priorities. Results: Confidentiality and privacy concerns varied in severity, and were most prevalent over Jelly Bean releases. Issues raised in regard to confidentiality related mostly to access, user credentials and permission management, while privacy concerns were mainly expressed about phone locking. Community users also expressed divergent preferences for new security features, ranging from more relaxed to very strict. Conclusions: Strategies that support continuous corrective measures for both old and new Android releases would likely maintain stakeholder confidence. An approach that provides users with basic default security settings, but with the power to configure additional security features if desired, would provide the best balance for Android's wide cohort of stakeholders

Security attacks taxonomy on bring your own devices (BYOD) model

Mobile devices, specifically smartphones, have become ubiquitous. For this reason, businesses are starting to develop “Bring Your Own Device” policies to allow their employees to use their owned devices in the workplace. BYOD offers many potential advantages: enhanced productivity, increased revenues, reduced mobile costs and IT efficiencies. However, due to emerging attacks and limitations on device resources, it is difficult to trust these devices with access to critical proprietary information. Therefore, in this paper, the potential attacks of BYOD and taxonomy of BYOD attacks are presented. Advanced persistent threat (APT) and malware attack are discussed in depth in this paper. Next, the proposed solution to mitigate the attacks of BYOD is discussed. Lastly, the evaluations of the proposed solutions based on the X. 800 security architecture are presented