Applying Formal Methods to Networking: Theory, Techniques and Applications

Despite its great importance, modern network infrastructure is remarkable for the lack of rigor in its engineering. The Internet which began as a research experiment was never designed to handle the users and applications it hosts today. The lack of formalization of the Internet architecture meant limited abstractions and modularity, especially for the control and management planes, thus requiring for every new need a new protocol built from scratch. This led to an unwieldy ossified Internet architecture resistant to any attempts at formal verification, and an Internet culture where expediency and pragmatism are favored over formal correctness. Fortunately, recent work in the space of clean slate Internet design---especially, the software defined networking (SDN) paradigm---offers the Internet community another chance to develop the right kind of architecture and abstractions. This has also led to a great resurgence in interest of applying formal methods to specification, verification, and synthesis of networking protocols and applications. In this paper, we present a self-contained tutorial of the formidable amount of work that has been done in formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial

Finding twin smooth integers by solving Pell equations

Any pair of consecutive B-smooth integers for a given smoothness bound B corresponds to a solution (x, y) of the equation x^2 - 2Dy^2 = 1 for a certain square-free, B-smooth integer D and a B-smooth integer y. This paper describes algorithms to find such twin B-smooth integers that lie in a given interval by using the structure of solutions of the above Pell equation. The problem of finding such twin smooth integers is motivated by the quest for suitable parameters to efficiently instantiate recent isogeny-based cryptosystems. While the Pell equation structure of twin B-smooth integers has previously been used to describe and compute the full set of such pairs for very small values of B, increasing B to allow for cryptographically sized solutions makes this approach utterly infeasible. We start by revisiting the Pell solution structure of the set of twin smooth integers. Instead of using it to enumerate all twin smooth pairs, we focus on identifying only those that lie in a given interval. This restriction allows us to describe algorithms that navigate the vast set of Pell solutions in a more targeted way. Experiments run with these algorithms have provided examples of twin B-smooth pairs that are larger and have smaller smoothness bound B than previously reported pairs. Unfortunately, those examples do not yet provide better parameters for cryptography, but we hope that our methods can be generalized or used as subroutines in future work to achieve that goal

Analysis of final state lepton polarization-dependent observables in H→ℓ+ℓ−γH\to \ell^{+}\ell^{-} \gamma in the SM at loop level

Recently, the CMS and ATLAS collaborations have announced the results for $H\rightarrow Z[\rightarrow \ell^{+}\ell^{-}]\gamma$ with $\ell=e$ or $\mu$, where $H\rightarrow Z\gamma$ is a sub-process of $H\rightarrow \ell^{+} \ell^{-} \gamma$. This semi-leptonic Higgs decay receives loop induced resonant $H\rightarrow Z[\rightarrow \ell^{+}\ell^{-}]\gamma$ as well as non-resonant contributions as discussed in. To probe further features coming from these contributions to $H\rightarrow \ell^{+} \ell^{-} \gamma$, we suggest that the polarization of the final state lepton is an important parameter. We show that the resonant and non-resonant cross-terms play an important role when the polarization of final state lepton is taken into account, which is negligible in the case of un-polarized leptons. For this purpose, we have calculated the polarized decay rates and the longitudinal, normal and transverse polarization asymmetries. We find that these asymmetries purely come from the loop contributions and are helpful to further investigate the resonant and non-resonant nature of $H\rightarrow Z[\rightarrow \ell^{+}\ell^{-}]\gamma$ decay. We observe that for $\ell=e,\mu$, the longitudinal decay rate is highly suppressed around $m_{\ell\ell}\approx 60$GeV when the final lepton spin is $-\frac{1}{2}$, dramatically increasing the corresponding lepton polarization asymmetries. Furthermore, we analyze another clean observable, the ratio of decay rates $\Gamma$, $R^{\ell\ell'}\equiv \frac{\Gamma_{H\rightarrow \ell^{+} \ell^{-} \gamma}}{\Gamma_{H\rightarrow \ell^{'+} \ell^{'-} \gamma}}$, where $\ell$ and $\ell'$ refer to different final state lepton generations. Therefore, the precise measurements of these observables at CMS and ATLAS can provide a fertile ground to test not only the Standard Model (SM) but also to examine the signatures of possible new physics (NP) beyond the SM.Comment: 28 pages, 7 figure

2D MXene Ti3C2Tx Enhanced Plasmonic Absorption in Metasurface for Terahertz Shielding

With the advancement of technology, shielding for terahertz (THz) electronic and communication equipment is increasingly important. The metamaterial absorption technique is mostly used to shield electromagnetic interference (EMI) in THz sensing technologies. The most widely used THz metamaterial absorbers suffer from their narrowband properties and the involvement of complex fabrication techniques. Materials with multifunctional properties, such as adjustable conductivity, broad bandwidth, high flexibility, and robustness, are driving future development to meet THz shielding applications. In this article, a theoretical simulation approach based on finite difference time domain (FDTD) is utilized to study the absorption and shielding characteristics of a two-dimensional (2D) MXene Ti3C2Tx metasurface absorber in the THz band. The proposed metamaterial structure is made up of a square-shaped array of MXene that is 50 nm thick and is placed on top of a silicon substrate. The bottom surface of the silicon is metalized with gold to reduce the transmission and ultimately enhance the absorption at 1–3 THz. The symmetric adjacent space between the MXene array results in a widening of bandwidth. The proposed metasurface achieves 96% absorption under normal illumination of the incident source and acquires an average of 25 dB shielding at 1 THz bandwidth, with the peak shielding reaching 65 dB. The results show that 2D MXene-based stacked metasurfaces can be proven in the realization of low-cost devices for THz shielding and sensing applications

Mental illness and injuries: emerging health challenges of urbanisation in South Asia

This article was published in the BMJ (Online) [© 2017 BMJ Publishing Group] and the definitive version is available at: http://doi.org10.1136/bmj.j1126 The Journal's website is at: http://www.bmj.com/content/357/bmj.j1126Publishe

Towards Mobile Edge Computing: Taxonomy, Challenges, Applications and Future Realms

The realm of cloud computing has revolutionized access to cloud resources and their utilization and applications over the Internet. However, deploying cloud computing for delay critical applications and reducing the delay in access to the resources are challenging. The Mobile Edge Computing (MEC) paradigm is one of the effective solutions, which brings the cloud computing services to the proximity of the edge network and leverages the available resources. This paper presents a survey of the latest and state-of-the-art algorithms, techniques, and concepts of MEC. The proposed work is unique in that the most novel algorithms are considered, which are not considered by the existing surveys. Moreover, the chosen novel literature of the existing researchers is classified in terms of performance metrics by describing the realms of promising performance and the regions where the margin of improvement exists for future investigation for the future researchers. This also eases the choice of a particular algorithm for a particular application. As compared to the existing surveys, the bibliometric overview is provided, which is further helpful for the researchers, engineers, and scientists for a thorough insight, application selection, and future consideration for improvement. In addition, applications related to the MEC platform are presented. Open research challenges, future directions, and lessons learned in area of the MEC are provided for further future investigation

A Survey: Implementations of Non-fungible Token System in Different Fields

In the realm of digital art and collectibles, NFTs are sweeping the board. Because of the massive sales to a new crypto audience, the livelihoods of digital artists are being transformed. It is no surprise that celebs are jumping on the bandwagon. It is a fact that NFTs can be used in multiple ways, including digital artwork such as animation, character design, digital painting, collection of selfies or vlogs, and many more digital entities. As a result, they may be used to signify the possession of any specific object, whether it be digital or physical. NFTs are digital tokens that may be used to indicate ownership of one of a-kind goods. For example, I can buy a shoe or T shirt from any store, and then if the store provides me the same 3D model of that T-Shirt or shoe of the exact same design and color, it would be more connected with my feelings. They enable us to tokenize items such as artwork, valuables, and even real estate. NFTs can only be owned by one person at a time, and they are protected by the Ethereum blockchain no one can alter the ownership record or create a new NFT. The word non-fungible can be used to describe items like your furniture, a song file, or your computer. It is impossible to substitute these goods with anything else because they each have their own distinct characteristics. The goal was to find all the existing implementations of Non-fungible Tokens in different fields of recent technology, so that an overall overview of future implementations of NFT can be found and how it can be used to enrich user experiences.Comment: 14 pages, 3 figures, 3 table

Transport time to trauma facilities in Karachi: an exploratory study

Background: Rapid urban growth in developing countries has outpaced the development of health infrastructure, including trauma centers, leading to potential delays in trauma care. This study was conducted in Karachi, a city of 16 million people in Pakistan. Aims: Our aim was to determine the time taken to reach the nearest 24-h emergency care facility (ECF) and the government-designated trauma center (TC). We also sought to determine the availability of supplies and equipment required for basic trauma care at these centers.Methods:We selected five towns in Karachi that had the highest number of road traffic injuries (RTIs) (as identified through medicolegal records). We then measured the time taken to reach the nearest ECF and the government-designated TC from four compass points within each town. We also asked about the equipment and supplies used in basic trauma care.Results: All three TCs in Karachi were located in the selected towns and were within 5.0-10.5 km of each other. The transport times to the 3 TCs were an average of 13.3 min (+/- 7.1) and to the 16 ECFs an average of 4.7 min (+/- 2.4) (p value \u3c 0.00). Most ECFs did not have all equipment and supplies necessary for basic trauma care, 90% had the basic equipment for management of airway, oxygen, and IV fluids, 70% had morphine, and 45% had C-spine collars. Conclusions: Vital time is lost in reaching a government-designated TC. ECFs might be an alternative option, but are not fully equipped and funded to provide adequate trauma care to all

Blockchain-Based Solution for COVID-19 Digital Medical Passports and Immunity Certificates

COVID-19 has emerged as a highly contagious disease which has caused a devastating impact across the world with a very large number of infections and deaths. Timely and accurate testing is paramount to an effective response to this pandemic as it helps identify infections and therefore mitigate (isolate/cure) them. In this paper, we investigate this challenge and contribute by presenting a blockchain-based solution that incorporates self-sovereign identity, re-encryption proxies, and decentralized storage, such as the interplanetary file systems (IPFS). Our solution implements digital medical passports (DMP) and immunity certificates for COVID-19 test-takers. We present smart contracts based on the Ethereum blockchain written and tested successfully to maintain a digital medical identity for test-takers that help in a prompt trusted response directly by the relevant medical authorities. We reduce the response time of the medical facilities, alleviate the spread of false information by using immutable trusted blockchain, and curb the spread of the disease through DMP. We present a detailed description of the system design, development, and evaluation (cost and security analysis) for the proposed solution. Since our code leverages the use of the on-chain events, the cost of our design is almost negligible. We have made our smart contract codes publicly available on Github

Can trained field community workers identify stroke using a stroke symptom questionnaire as well as neurologists? Adaptation and validation of a community worker administered stroke symptom questionnaire in a peri-urban Pakistani community.

Background: Stroke is a leading cause of morbidity and mortality worldwide. There is a paucity of data from South Asia where stroke is highly prevalent. Validated tools administrable by Community Health Workers (CHWs) are required to identify stroke in the community in a resource strapped region such as this. Methods: The study was conducted in a transitional slum in Karachi, Pakistan. Questionnaire for Verifying Stroke-Free Status (QVSFS) was adapted and translated into Urdu. Two CHWs, trained by a neurologist, selected 322 community dwelling subjects using purposive sampling. Each CHW collected data independently which was validated by a vascular neurologist who directly examined each participant. To assess the effect of audit and feedback, data from the final 10% of the subjects was collected following a second training session for the CHWs. Sensitivity, specificity and Cohen’s kappa was determined for the CHW administered questionnaire against neurovascular assessment. Results: Mean age of participants was 56.5 years with 71% of participants being women. The sensitivity and specificity of the questionnaire of detecting stroke was 77.1% (CI: 64.1%–86.9%) and 85.8% (CI: 83.5%–87.5%). The chance corrected agreement using the Cohen’s Kappa statistic was 0.51 (CI: 0.38–0.60). Kappa ranged from 0.37 to 0.58 for each of the seven stroke symptoms. Hemianesthesia (72.9%) and hemiplegia (64.6%) were the most sensitive symptoms. The performance and agreement improved from moderate to substantial after audit and feedback. Conclusion: We found a reasonable sensitivity and specificity and moderate agreement between CHW administered QVSFS and assessment by a vascular neurologist