bluuebunny/crossref_metadata_2025 huggingface dataset:
JITPR
Authors: Sidiropoulos Harry , Siozios Kostas , Figuli Peter , Soudris Dimitrios , Hübner Michael , Becker Jürgen
Published: April 2020

The execution runtime usually is a headache for designers performing application mapping onto reconfigurable architectures. In this article we propose a methodology, as well as the supporting toolset, targeting to provide fast application implementation onto reconfigurable architectures with the usage of a Just-In-Time (JIT) compilation framework. Experimental results prove the efficiency of the introduced framework, as we reduce the execution runtime compared to the state-of-the-art approach on average by 53.5×. Additionally, the derived solutions achieve higher operation frequencies by 1.17×, while they also exhibit significant lower fragmentation ratios of hardware resources.
Verifying autonomous systems
Authors: Fisher Michael , Dennis Louise , Webster Matt
Published: April 2020

Exploring autonomous systems and the agents that control them.
The other side of language
Authors: Denning Peter J.
Published: April 2020

The conversation for action gives a framework for completing professional actions effectively.
Examining a Large Keystroke Biometrics Dataset for Statistical-Attack Openings
Authors: Serwadda Abdul , Phoha Vir V.
Published: April 2020

Research on keystroke-based authentication has traditionally assumed human impostors who generate forgeries by physically typing on the keyboard. With bots now well understood to have the capacity to originate precisely timed keystroke sequences, this model of attack is likely to underestimate the threat facing a keystroke-based system in practice. In this work, we investigate how a keystroke-based authentication system would perform if it were subjected to synthetic attacks designed to mimic the typical user. To implement the attacks, we perform a rigorous statistical analysis on keystroke biometrics data collected over a 2-year period from more than 3000 users, and then use the observed statistical traits to design and launch algorithmic attacks against three state-of-the-art password-based keystroke verification systems.

Relative to the zero-effort attacks typically used to test the performance of keystroke biometric systems, we show that our algorithmic attack increases the mean Equal Error Rates (EERs) of three high performance keystroke verifiers by between 28.6% and 84.4%. We also find that the impact of the attack is more pronounced when the keystroke profiles subjected to the attack are based on shorter strings, and that some users see considerably greater performance degradation under the attack than others. This article calls for a shift from the traditional zero-effort approach of testing the performance of password-based keystroke verifiers, to a more rigorous algorithmic approach that captures the threat posed by today’s bots.
Ubik
Authors: Kasture Harshad , Sanchez Daniel
Published: April 2020

Chip-multiprocessors (CMPs) must often execute workload mixes with different performance requirements. On one hand, user-facing, latency-critical applications (e.g., web search) need low tail (i.e., worst-case) latencies, often in the millisecond range, and have inherently low utilization. On the other hand, compute-intensive batch applications (e.g., MapReduce) only need high long-term average performance. In current CMPs, latency-critical and batch applications cannot run concurrently due to interference on shared resources. Unfortunately, prior work on quality of service (QoS) in CMPs has focused on guaranteeing average performance, not tail latency.

In this work, we analyze several latency-critical workloads, and show that guaranteeing average performance is insufficient to maintain low tail latency, because microarchitectural resources with state, such as caches or cores, exert inertia on instantaneous workload performance. Last-level caches impart the highest inertia, as workloads take tens of milliseconds to warm them up. When left unmanaged, or when managed with conventional QoS frameworks, shared last-level caches degrade tail latency significantly. Instead, we propose Ubik, a dynamic partitioning technique that predicts and exploits the transient behavior of latency-critical workloads to maintain their tail latency while maximizing the cache space available to batch applications. Using extensive simulations, we show that, while conventional QoS frameworks degrade tail latency by up to 2.3x, Ubik simultaneously maintains the tail latency of latency-critical workloads and significantly improves the performance of batch applications.
Finding the limit
Authors: Ding Yufei , Zhou Mingzhou , Zhao Zhijia , Eisenstat Sarah , Shen Xipeng
Published: April 2020

This work aims to find out the full potential of compilation scheduling for JIT-based runtime systems. Compilation scheduling determines the order in which the compilation units (e.g., functions) in a program are to be compiled or recompiled. It decides when what versions of the units are ready to run, and hence affects performance. But it has been a largely overlooked direction in JIT-related research, with some fundamental questions left open: How significant compilation scheduling is for performance, how good the scheduling schemes employed by existing runtime systems are, and whether a great potential exists for improvement. This study proves the strong NP-completeness of the problem, proposes a heuristic algorithm that yields near optimal schedules, examines the potential of two current scheduling schemes empirically, and explores the relations with JIT designs. It provides the first principled understanding to the complexity and potential of compilation scheduling, shedding some insights for JIT-based runtime system improvement.
Deterministic galois
Authors: Nguyen Donald , Lenharth Andrew , Pingali Keshav
Published: April 2020

Non-determinism in program execution can make program development and debugging difficult. In this paper, we argue that solutions to this problem should be on-demand, portable and parameterless. On-demand means that the programming model should permit the writing of non-deterministic programs since these programs often perform better than deterministic ones for the same problem. Portable means that the program should produce the same answer even if it is run on different machines. Parameterless means that if there are machine-dependent scheduling parameters that must be tuned for good performance, they must not affect the output.

Although many solutions for deterministic program execution have been proposed in the literature, they fall short along one or more of these dimensions. To remedy this, we propose a new approach, based on the Galois programming model, in which (i) the programming model permits the writing of non-deterministic programs and (ii) the runtime system executes these programs deterministically if needed. Evaluation of this approach on a collection of benchmarks from the PARSEC, PBBS, and Lonestar suites shows that it delivers deterministic execution with substantially less overhead than other systems in the literature.
VSwapper
Authors: Amit Nadav , Tsafrir Dan , Schuster Assaf
Published: April 2020

The number of guest virtual machines that can be consolidated on one physical host is typically limited by the memory size, motivating memory overcommitment. Guests are given a choice to either install a "balloon" driver to coordinate the overcommitment activity, or to experience degraded performance due to uncooperative swapping. Ballooning, however, is not a complete solution, as hosts must still fall back on uncooperative swapping in various circumstances. Additionally, ballooning takes time to accommodate change, and so guests might experience degraded performance under changing conditions.

Our goal is to improve the performance of hosts when they fall back on uncooperative swapping and/or operate under changing load conditions. We carefully isolate and characterize the causes for the associated poor performance, which include various types of superfluous swap operations, decayed swap file sequentiality, and ineffective prefetch decisions upon page faults. We address these problems by implementing VSwapper, a guest-agnostic memory swapper for virtual environments that allows efficient, uncooperative overcommitment. With inactive ballooning, VSwapper yields up to an order of magnitude performance improvement. Combined with ballooning, VSwapper can achieve up to double the performance under changing load conditions.
K2
Authors: Lin Felix Xiaozhu , Wang Zhen , Zhong Lin
Published: April 2020

Mobile System-on-Chips (SoC) that incorporate heterogeneous coherence domains promise high energy efficiency to a wide range of mobile applications, yet are difficult to program. To exploit the architecture, a desirable, yet missing capability is to replicate operating system (OS) services over multiple coherence domains with minimum inter-domain communication. In designing such an OS, we set three goals: to ease application development, to simplify OS engineering, and to preserve the current OS performance. To this end, we identify a shared-most OS model for multiple coherence domains: creating per-domain instances of core OS services with no shared state, while enabling other extended OS services to share state across domains. To test the model, we build K2, a prototype OS on the TI OMAP4 SoC, by reusing most of the Linux 3.4 source. K2 presents a single system image to applications with its two kernels running on top of the two coherence domains of OMAP4. The two kernels have independent instances of core OS services, such as page allocator and interrupt management, as coordinated by K2; the two kernels share most extended OS services, such as device drivers, whose state is kept coherent transparently by K2. Despite platform constraints and unoptimized code, K2 improves energy efficiency for light OS workloads by 8x-10x, while incurring less than 6% performance overhead for a device driver shared between kernels. Our experiences with K2 show that the shared-most model is promising.
High-performance fractal coherence
Authors: Voskuilen Gwendolyn , Vijaykumar T.N.
Published: April 2020

Bugs in cache coherence protocols can cause system failures. Despite many advances, verification runs into state explosion for even moderately-sized systems. As multicores' core counts increase, coherence verifiability continues to be a key problem. A recent proposal, called fractal coherence, avoids the state explosion problem by applying the idea of observational equivalence between a larger system and its smaller sub-systems. A fractal protocol for a larger system is verified by design if a minimal sub-system is verified completely. While fractal coherence is a significant step forward, there are two shortcomings: (1) Architectural limitation: To achieve fractal coherence's logical hierarchy, TreeFractal, the specific fractal protocol, employs a tree architecture where each miss traverses many levels up and down the tree and each level redundantly holds its sub-trees' coherence tags. (2) Protocol restrictions: TreeFractal imposes a restriction on responses to read requests that forces read requests to obtain clean blocks from the nearest sharer even if the shared L2 or L3 is faster. These limitations impose significant performance and coherence tag state overheads. In this paper, we propose architectural support for coherence protocols to achieve scalable performance and verifiability. To address the architectural limitation, we propose FlatFractal, a directory-based architecture which decouples fractal coherence's logical hierarchy from the architecture and eliminates redundant tag state. To address the protocol restriction, we propose a simple change to the protocol that, while preserving observational equivalence, allows read requests to obtain the blocks from the shared L2 or L3. Our simulations show that for 16 cores, FlatFractal performs, on average, 57% better than TreeFractal and within 3% of a conventional directory.
Homotopy type theory
Authors: Awodey Steve , Harper Robert
Published: April 2020

Homotopy type theory is a recently-developed unification of previously disparate frameworks, which can serve to advance the project of formalizing and mechanizing mathematics. One framework is based on a computational conception of the type of a construction, the other is based on a homotopical conception of the homotopy type of a space. The computational notion of type has its origins in Brouwer's program of intuitionism, and Church's λ-calculus, both of which sought to ground mathematics in computation (one would say "algorithm" these days). The homotopical notion comes from Grothendieck's late conception of homotopy types of spaces as represented by ∞-groupoids [Grothendieck 1983]. The computational perspective was developed most fully by Per Martin-Löf, leading in particular to his Intuitionistic Theory of Types [Martin-Löf and Sambin 1984], on which the formal system of homotopy type theory is based. The connection to homotopy theory was first hinted at in the groupoid interpretation of Hofmann and Streicher [Hofmann and Streicher 1994; 1995]. It was then made explicit by several researchers, roughly simultaneously. The connection was clinched by Voevodsky's introduction of the
univalence axiom
, which is motivated by the homotopical interpretation, and which relates type equality to homotopy equivalence [Kapulkin et al. 2012; Awodey et al. 2013].
Flow caching for high entropy packet fields
Authors: Shelly Nick , Jackson Ethan J. , Koponen Teemu , McKeown Nick , Rajahalme Jarno
Published: April 2020

Packet classification on general purpose CPUs remains expensive regardless of advances in classification algorithms. Unless the packet forwarding pipeline is both simple and static in function, fine-tuning the system for optimal forwarding is a time-consuming and brittle process. Network virtualization and network function virtualization value general purpose CPUs exactly for their flexibility: in such systems, a single x86 forwarding element does not implement a single, static classification step but a sequence of dynamically reconfigurable and potentially complex forwarding operations. This leaves a software developer looking for maximal packet forwarding throughput with few options besides flow caching. In this paper, we consider the problem of flow caching and more specifically, how to cache forwarding decisions that depend on packet fields with high entropy (and therefore, change often); to this end, we arrive at algorithms that allow us to efficiently compute near optimal flow cache entries spanning several transport connections, even if forwarding decisions depend on transport protocol headers.
Traffic steering in software defined networks
Authors: Cao Zizhong , Kodialam Murali , Lakshman T. V.
Published: April 2020

Middleboxes have become ubiquitous in data center as well as wide area networks. Simple routing of flows from ingress to egress along shortest paths has been replaced by policy aware paths that have to pass through the required set of middleboxes. The complex routing is one of the major impetus for the Software Defined Networking (SDN) paradigm. In this paper, we consider both offline planning and online routing problems in SDN framework. The offline planning problem is one where aggregate demands are specified and the objective is to determine whether there is enough capacity in the network to handle the demands. We develop a fast FPTAS for the problem based on segmentation and lazy dual update. In the online routing problem, flow requests are given one at a time and the objective is to steer the flows to maximize the total amount of traffic accepted over time. We develop a log-competitive algorithm based on time-dependent duals.
Cross-Kernel Control-Flow--Graph Analysis for Event-Driven Real-Time Systems
Authors: Dietrich Christian , Hoffmann Martin , Lohmann Daniel
Published: April 2020

Embedded real-time control systems generally have a dedicated purpose and fixed set of functionalities. This manifests in a large amount of implicit and explicit static knowledge, available already at compile time. Modern compilers can extract and exploit this information to perform extensive whole-program analyses and interprocedural optimizations. However, these analyses typically end at the application--kernel boundary, thus control-flow transitions between different threads are not covered, yet. This restriction stems from the pessimistic assumption of a probabilistic scheduling policy of the underlying operating system, impeding detailed predictions of the overall system behavior. Real-time operating systems, however, do provide deterministic and exactly specified scheduling decisions, as embedded control systems rely on a timely and precise behavior.

In this paper, we present an approach that incorporates the RTOS semantics into the control-flow analysis, to cross the application--kernel boundary. By combining operating system semantics, the static system configuration and the application logic, we determine a cross-kernel control-flow--graph, that provides a global view on all possible execution paths of a real-time system. Having this knowledge at hand, enables us to tailor the operating system kernel more closely to the particular application scenario. On the example of a real-world safety-critical control system, we present two possible use cases: Run-time optimizations, by means of specialized system calls for each call site, allow to speed up the kernel execution path by 33 percent in our benchmark scenario. An automated generation of OS state assertions on the expected system behavior, targeting transient hardware fault tolerance, leverages significant robustness improvements.
The tale of the quantifier alternation hierarchy of first-order logic over words
Authors: Place Thomas , Zeitoun Marc
Published: April 2020

In this survey, we present ideas developed until recently in order to understand the expressive power of logical fragments in the quantifier alternation hierarchy of first-order logic interpreted on finite words.
Automata column
Authors: Bojańczyk Mikołaj
Published: April 2020

This is a survey of extensions of logics and automata which talk about boundedness. A typical property of interest is the set of ω-words which satisfy "there exists some
k
, such that every
a
letter is followed by a
b
letter in at most
k
steps". The main points of interest are the logic
mso+u
, its fragments and related automata models, as well as the regular cost functions of Colcombet.
Prospects for the internet of things
Authors: Cerf Vinton G.
Published: April 2020

The future of the Internet of Things may rely on our ability to tackle issues of safety, security, and privacy, while creating standardized systems that are easy to use and configure.
Semantics column
Authors: Mislove Michael
Published: April 2020

In this quarter's column, Andrzej Murawski and Nikos Tzevelekos offer us an invitation to game semantics. This approach to giving semantics originated in work of the philosopher and mathematician Paul Lorenzen in the late 1950s [10], who viewed the meaning of a proposition ϕ as a dialogue between two players, a proponent who asserts ϕ, and an opponent, who denies ϕ. A proof of ϕ is then a winning strategy for proponent. The approach was used by Andreas Blass [5] to give a semantics to Girard's linear logic [7]. Noting some shortcomings in Blass's model, Abramsky and Jagadeesan [2] refined the model to devise a more expressive game semantics for multiplicative linear logic.
Conference reports
Authors: Pérez Jorge A.
Published: April 2020

This installment of the conference report column includes two nice personal recollections on two recent (and closely related) events on programming language research:

---Fritz Henglein (University of Copenhagen, Denmark) offers some personal impressions on POPL 2016: the 43rd ACM Symposium on Principles of Programming Languages, which took place in St. Petersburg, Florida, during January 20-22, 2016.
2016 POPL impressions
Authors: Henglein Fritz
Published: April 2020

The 43rd ACM Symposium on Principles of Programming Languages, POPL, took place in St. Petersburg, Florida, January 20th--22nd. POPL is the longest-running annual conference series in programming languages. It is one of SIGPLAN's four flagship conferences and has throughout its history consistently been one of the most highly regarded programming language research conferences. Like its sibling conference, Programming Language Design and Implementation (PLDI), POPL covers both theoretical and experimental topics, but traditionally leans more to the left where the PLDI leans more to the right on the theory-practice spectrum. (Another difference is that POPL does not declare itself to be the premier forum, just a forum for programming language research.)
Unmanned aircraft systems in the national airspace system
Authors: Muñoz César A. , Dutle Aaron , Narkawicz Anthony , Upchurch Jason
Published: April 2020

As the technological and operational capabilities of unmanned aircraft systems (UAS) have grown, so too have international efforts to integrate UAS into civil airspace. However, one of the major concerns that must be addressed in realizing this integration is that of safety. For example, UAS lack an on-board pilot to comply with the legal requirement that pilots see and avoid other aircraft. This requirement has motivated the development of a detect and avoid (DAA) capability for UAS that provides situational awareness and maneuver guidance to UAS operators to aid them in avoiding and remaining well clear of other aircraft in the airspace. The NASA Langley Research Center Formal Methods group has played a fundamental role in the development of this capability. This article gives a selected survey of the formal methods work conducted in support of the development of a DAA concept for UAS. This work includes specification of low-level and high-level functional requirements, formal verification of algorithms, and rigorous validation of software implementations.
Probabilistic bisimilarity distances
Authors: van Breugel Franck
Published: April 2020

In a recent column, Panangaden discusses probabilistic bisimilarity. Here, we show how probabilistic bisimilarity can be quantitatively generalized leading to probabilistic bisimilarity distances.
POPSTAR
Authors: Delaune Stéphanie
Published: April 2020

The shrinking size of microprocessors as well as the ubiquity of wireless communication have led to the proliferation of portable computing devices with novel security requirements. Whereas traditional security protocols achieve their security goals relying solely on cryptographic primitives like encryptions and hash functions, the protocols employed to secure these devices establish and rely in addition on properties of the physical world. For instance, they may use, as basic building blocks, protocols for ensuring physical proximity, secure localisation, or secure neighbourhood discovery.

The aim of the POPSTAR ERC project is to develop techniques and tools to analyse protocols that establish and rely on properties of the physical world. We foresee that, at the end of the project, appropriate verification tools will be available to analyse the security and privacy of these "physical protocols". The research community in logics, program verification, and security has already a long tradition in developing techniques and tools to analyse key establishment and authentication protocols. Distance bounding protocols which are used to provide secure proximity control, raise new research challenges, and can not be analysed today using off-the-shelf verification tools.
Verification column
Authors: Lazić Ranko
Published: April 2020

Any computer scientist who does research in logic and verification will sooner or later cross their path with Presburger arithmetic. This column, authoritatively and accessibly composed by Christoph Haase, fills the gap for a state-of-the-art introduction to the logic of Presburger arithmetic and its algorithmic properties. As well as conveying an illuminating brief history, the article provides plenty of pointers to ongoing cutting-edge work.
Conference reports
Authors: Pérez Jorge A
Published: April 2020

In this installment of the conference report column, Claudio Antares Mezzina reports on the 13th International Federated Conference on Distributed Computing Techniques (DisCoTec 2018), which took place in Madrid (Spain) during June 18--21, 2018.
1
This was the 13th edition of this event, which included three conferences (COORDINATION, DAIS, and FORTE) and one workshop (ICE). I am most grateful to Claudio for his detailed report.
Session details: Selected extended papers from SBESC 2012 Brazilian symposium on computing system engineering
Authors: de Faria Corrêa Edgard , Kreutz Marcio Eduardo
Published: April 2020

The Brazilian Symposium on Computing System Engineering (SBESC) is an initiative of the research community originally associated with three events: the Brazilian Workshop on Real-Time Systems, created in 1998; the Brazilian Workshop on Operating Systems, created in 2004; and the Brazilian Workshop on Embedded Systems, created in 2010. The identification of a strong synergy among these research areas added to the fact that designing computing systems is an increasingly multidisciplinary task has motivated the workshops to move from their native conferences to form an independent symposium. The broad term "Computing System Engineering" emerged in the context of contemporary Cyber-Physical Systems, which challenge Engineers and Scientist as they shape a new reality for modern societies.

This year, the symposium was hosted by the Federal University of Rio Grande do Norte (UFRN) in the beautiful coastal city of Natal in Northeast Brazil. The program spanned a whole week, from November 5 to 9, and was organized in two big blocks: peer-reviewed paper sessions and tutorials. The event was organized by UFRN's Computer Science Department (DIMAP), sponsored by the Brazilian Computing Society (SBC), and financed by CAPES, CNPq, and FAPERN.

SBESC's Technical Program Committee also selected two papers from those presented at the symposium addressing operating systems issues to appear in the Operating Systems Review and thus offer ACM fellows a glimpse of the event. Authors were invited to extend and improve their manuscripts with recent research results. The first paper, On the Formal Verification of Component-based Embedded Operating Systems, by M. Ludwich and A. Frohlich, introduces an approach to formally verify the functional correctness and safety properties of embedded operating system components described at system-level. The convergence between software and hardware in the domain of embedded systems is pressing operating systems in the filed to deliver their services both as software and as hardware. In such a scenario, it is desirable to verify system properties regardless of whether components are instantiated as software or hardware. The approach combines software model checking and programming by contract concepts to address such issues. The second, Adaptive Request Batching for Byzantine Replication, by A. de Sa, A. Freitas, and R. Macedo, proposes an adaptation of the Practical Byzantine Fault Tolerance algorithm proposed by Liskov and Castro to increase its performance. The original PBFT algorithm uses a batch to store client requests on the primary replica. Requests in a batch are handled together, aiming at decreasing the time spent with message authentication. The adaptation strategy dynamically varies the batch size and the batch time-out according with application activity.
Constraint satisfaction problems
Authors: Bulatov Andrei A.
Published: April 2020

In this paper we briefly survey the history of the Dichotomy Conjecture for the Constraint Satisfaction problem, that was posed 25 years ago by Feder and Vardi. We outline some of the approaches to this conjecture, and then describe an algorithm that yields an answer to the conjecture.
Federated logic conference (FLoC) at Oxford
Authors: Ahmed Daniele , Fletcher Katherine , Gutierrez Julian
Published: April 2020

Oxford University was proud to host the Federated Logic Conference (FLoC), in July of 2018. FLoC is a meta-conference, which occurs every 4 years, with the 2018 edition bringing together 9 major conferences in the fields of logic and foundations of computer science. With 9 headline conferences, nearly 80 workshops, a summer school, a public lecture and a public debate in the Oxford Union (and a variety of social events), FLoC 2018 hosted over 2000 individuals between 30 June and 19 July. The stars of the show were the 9 lead conferences: CAV, CSF, FM, FSCD, ICLP, IJCAR, ITP, LICS and SAT.
Trust-Aware Decision Making for Human-Robot Collaboration
Authors: Chen Min , Nikolaidis Stefanos , Soh Harold , Hsu David , Srinivasa Siddhartha
Published: April 2020

Trust in autonomy is essential for effective human-robot collaboration and user adoption of autonomous systems such as robot assistants. This article introduces a computational model that integrates trust into robot decision making. Specifically, we learn from data a partially observable Markov decision process (POMDP) with human trust as a latent variable. The trust-POMDP model provides a principled approach for the robot to (i) infer the trust of a human teammate through interaction, (ii) reason about the effect of its own actions on human trust, and (iii) choose actions that maximize team performance over the long term. We validated the model through human subject experiments on a table clearing task in simulation (201 participants) and with a real robot (20 participants). In our studies, the robot builds human trust by manipulating low-risk objects first. Interestingly, the robot sometimes fails intentionally to modulate human trust and achieve the best team performance. These results show that the trust-POMDP calibrates trust to improve human-robot team performance over the long term. Further, they highlight that maximizing trust alone does not always lead to the best performance.
StyloThai:
Authors: Sarwar Raheem , Porthaveepong Thanasarn , Rutherford Attapol , Rakthanmanon Thanawin , Nutanong Sarana
Published: April 2020

Authorship identification helps to identify the true author of a given anonymous document from a set of candidate authors. The applications of this task can be found in several domains, such as law enforcement agencies and information retrieval. These application domains are not limited to a specific language, community, or ethnicity. However, most of the existing solutions are designed for English, and a little attention has been paid to Thai. These existing solutions are not directly applicable to Thai due to the linguistic differences between these two languages. Moreover, the existing solution designed for Thai is unable to (i) handle outliers in the dataset, (ii) scale when the size of the candidate authors set increases, and (iii) perform well when the number of writing samples for each candidate author is low. We identify a stylometric feature space for the Thai authorship identification task. Based on our feature space, we present an authorship identification solution that uses the probabilistic
k
nearest neighbors classifier by transforming each document into a collection of point sets. Specifically, this document transformation allows us to (i) use set distance measures associated with an outlier handling mechanism, (ii) capture stylistic variations within a document, and (iii) produce multiple predictions for a query document. We create a new Thai authorship identification corpus containing 547 documents from 200 authors, which is significantly larger than the corpus used by the existing study (an increase of 32 folds in terms of the number of candidate authors). The experimental results show that our solution can overcome the limitations of the existing solution and outperforms all competitors with an accuracy level of 91.02%. Moreover, we investigate the effectiveness of each stylometric features category with the help of an ablation study. We found that combining all categories of the stylometric features outperforms the other combinations. Finally, we cross compare the feature spaces and classification methods of all solutions. We found that (i) our solution can scale as the number of candidate authors increases, (ii) our method outperforms all the competitors, and (iii) our feature space provides better performance than the feature space used by the existing study.
Countering Fragmentation in an Enterprise Storage System
Authors: Kesavan Ram , Curtis-Maury Matthew , Devadas Vinay , Mishra Kesari
Published: April 2020

As a file system ages, it can experience multiple forms of fragmentation. Fragmentation of the free space in the file system can lower write performance and subsequent read performance. Client operations as well as internal operations, such as deduplication, can fragment the layout of an individual file, which also impacts file read performance. File systems that allow sub-block granular addressing can gather intra-block fragmentation, which leads to wasted free space. Similarly, wasted space can also occur when a file system writes a collection of blocks out to object storage as a single large object, because the constituent blocks can become free at different times. The impact of fragmentation also depends on the underlying storage media. This article studies each form of fragmentation in the NetApp
®
WAFL
®
file system, and explains how the file system leverages a storage virtualization layer for defragmentation techniques that physically relocate blocks efficiently, including those in read-only snapshots. The article analyzes the effectiveness of these techniques at reducing fragmentation and improving overall performance across various storage media.
Enhancement and Application of a UAV Control Interface Evaluation Technique
Authors: Zhang Wenjuan , Feltner David , Shirley James , Kaber David , Neubert Manida S.
Published: April 2020

UAV supervisory control interfaces are important for safe operations and mission performance. We reviewed existing UAV interface design and evaluation tools and identified limitations. To address issues with existing methods, we developed an enhanced evaluation tool, the M-GEDIS-UAV. The tool includes detailed criteria for all aspects of UAV control interface design to support operator performance. It also supports quantitative and objective assessment of an interface. We prototyped three UAV information displays, including a digital control display, analog control display, and “massive” data display, as part of a simulated supervisory control interface. Six analysts, including three human factors experts and three novices evaluated the interfaces using the M-GEDIS-UAV. Inter-rater reliability was high for the human factors experts, suggesting training in usability analysis is necessary for tool application. Results also revealed the massive data display to produce significantly lower evaluation scores than the other displays. We concluded that the M-GEDIS-UAV was sensitive to interface manipulations and was most effectively used by human factors experts. Using the M-GEDIS-UAV tool can reveal the majority of design deviations from guidelines early in the design process toward increasing the effectiveness of control interfaces.
Mimicry Attacks on Smartphone Keystroke Authentication
Authors: Khan Hassan , Hengartner Urs , Vogel Daniel
Published: April 2020

Keystroke behaviour-based authentication employs the unique typing behaviour of users to authenticate them. Recent such proposals for virtual keyboards on smartphones employ diverse temporal, contact, and spatial features to achieve over 95% accuracy. Consequently, they have been suggested as a second line of defense with text-based password authentication. We show that a state-of-the-art keystroke behaviour-based authentication scheme is highly vulnerable against mimicry attacks. While previous research used training interfaces to attack physical keyboards, we show that this approach has limited effectiveness against virtual keyboards. This is mainly due to the large number of diverse features that the attacker needs to mimic for virtual keyboards. We address this challenge by developing an augmented reality-based app that resides on the attacker’s smartphone and leverages computer vision and keystroke data to provide real-time guidance during password entry on the victim’s phone. In addition, we propose an audiovisual attack in which the attacker overlays transparent film printed with spatial pointers on the victim’s device and uses audio cues to match the temporal behaviour of the victim. Both attacks require neither tampering or installing software on the victim’s device nor specialized hardware. We conduct experiments with 30 users to mount over 400 mimicry attacks. We show that our methods enable an attacker to mimic keystroke behaviour on virtual keyboards with little effort. We also demonstrate the extensibility of our augmented reality-based technique by successfully mounting mimicry attacks on a swiping behaviour-based continuous authentication system.
Fast Turnaround HLS Debugging Using Dependency Analysis and Debug Overlays
Authors: Jamal Al-Shahna , Cahill Eli , Goeders Jeffrey , Wilton Steven J. E.
Published: April 2020

High-level synthesis (HLS) has gained considerable traction over recent years, as it allows for faster development and verification of hardware accelerators than traditional RTL design. While HLS allows for most bugs to be caught during software verification, certain non-deterministic or data-dependent bugs still require debugging the actual hardware system during execution. Recent work has focused on techniques to allow designers to perform in-system debug of HLS circuits in the context of the original software code; however, like RTL debug, the user must still determine the root cause of a bug using small execution traces, with lengthy debug turns.

In this work, we demonstrate techniques aimed at reducing the time HLS designers spend performing in-system debug. Our approaches consist of performing data dependency analysis to guide the user in selecting which variables are observed by the debug instrumentation, as well as an associated debug overlay that allows for rapid reconfiguration of the debug logic, enabling rapid switching of variable observation between debug iterations. In addition, our overlay provides additional debug capability, such as selective function tracing and conditional buffer freeze points. We explore the area overhead of these different overlay features, showing a basic overlay with only a 1.7% increase in area overhead from the baseline debug instrumentation, while a deluxe variant offers 2×--7× improvement in trace buffer memory utilization with conditional buffer freeze support.
Verification column
Authors: Lazić Ranko
Published: April 2020

Like the photograph, this issue's verification column may not be entirely formal and horizontal, but like the tea, it is refreshingly authentic and inspiring. I think it will serve the community well in years to come!
Comparative label-free mass spectrometric analysis of temporal changes in the skeletal muscle proteome after impact trauma in rats
Authors: Liu Lian , Broszczak Daniel A. , Broadbent James A. , Singh Daniel P. , Steck Roland , Parker Tony J. , Peake Jonathan M.
Published: April 2020

Proteomics offers the opportunity to identify and quantify many proteins and to explore how they correlate and interact with each other in biological networks. This study aimed to characterize changes in the muscle proteome during the destruction, repair, and early-remodeling phases after impact trauma in male Wistar rats. Muscle tissue was collected from uninjured control rats and rats that were euthanized between 6 h and 14 days after impact injury. Muscle tissue was analyzed using unbiased, data-independent acquisition LC-MS/MS. We identified 770 reviewed proteins in the muscle tissue, 296 of which were differentially abundant between the control and injury groups ( P ≤ 0.05). Around 50 proteins showed large differences (≥10-fold) or a distinct pattern of abundance after injury. These included proteins that have not been identified previously in injured muscle, such as ferritin light chain 1, fibrinogen γ-chain, fibrinogen β-chain, osteolectin, murinoglobulin-1, T-kininogen 2, calcium-regulated heat-stable protein 1, macrophage-capping protein, retinoid-inducible serine carboxypeptidase, ADP-ribosylation factor 4, Thy-1 membrane glycoprotein, and ADP-ribosylation factor-like protein 1. Some proteins increased between 6 h and 14 days, whereas other proteins increased in a more delayed pattern at 7 days after injury. Bioinformatic analysis revealed that various biological processes, including regulation of blood coagulation, fibrinolysis, regulation of wound healing, tissue regeneration, acute inflammatory response, and negative regulation of the immune effector process, were enriched in injured muscle tissue. This study advances the understanding of early muscle healing after muscle injury and lays a foundation for future mechanistic studies on interventions to treat muscle injury.
Partnering with Palliative Care: A Case Report of Severe Pain in Critical Limb Ischemia Treated Successfully with a Continuous Popliteal Nerve Catheter
Authors: D’Souza Ryan S. , Shen Stephanie , Ojukwu Frederick , Gazelka Halena M. , Pulos Bridget P.
Published: April 2020

Background. Critical limb ischemia (CLI) is limb pain occurring at rest or impending limb loss as a result of lack of blood flow to the affected extremity. CLI pain is challenging to control despite multimodal pharmacologic analgesia and surgical intervention. We described the successful use of a continuous local anesthetic infusion via a popliteal nerve catheter to control severe refractory ischemic lower limb pain in a patient who failed surgical intervention and performed a brief narrative literature review on regional anesthesia for ischemic pain.Case Presentation. A 74-year-old female with acute myelogenous leukemia presented with CLI after experiencing left popliteal artery occlusion. Palliative medicine service was consulted for pain management in the setting of escalating narcotic dose requirements. She experienced a complicated hospital course with several failed attempts at surgical revascularization due to arterial rethrombosis. In accordance with the patient’s goals of care, a continuous popliteal nerve catheter was placed, despite the high risk nature of an intervention in an immunocompromised patient with thrombocytopenia (platelet count of 30,000 platelets/microliter) and ongoing therapeutic anticoagulation. The patient experienced immediate relief while transitioning to comfort care.Conclusion. This is the first report of successful analgesia for CLI via a continuous popliteal catheter in a patient with rethrombosis and failed surgical revascularization. Based on our collaborative experience, we recommend the development of partnerships between the acute pain service and palliative care service to facilitate the early evaluation and decision to utilize regional anesthesia for treatment of CLI.
Combining a Cognitive Concurrent Task with a Motor or Motor-Cognitive Task: Which Is Better to Differentiate Levels of Affectation in Parkinson’s Disease?
Authors: Pereiro Arturo X. , Resúa Bea , Facal David , Cancela-Carral José María
Published: April 2020

Introduction. Cognitive decline usually coexists with motor impairment in PD. Multitask settings provide appropriate measures to evaluate the complex interaction between motor and cognitive impairments. The main objective was to analyze which concurrent task, i. e., motor or hybrid motor-cognitive, in combination with a cognitive task better differentiates between PD patients with mild and moderate levels of disease. Methods. Thirty-seven individuals (19 male and 18 female) with idiopathic PD performed dual and triple tasks combining a cognitive task (phonemic fluency) with motor (pedaling) and/or cognitive-motor hybrid (tracking) tasks. Mild and moderate disability PD groups were specified considering the Hoehn and Yahr scale. Mixed ANOVA analyses for each of the concurrent task were carried out to test differences between the single and dual or triple condition performances comparing the low and high PD disability groups. Supplementary mixed ANCOVA analysis was performed considering the cognitive status as the covariate. Results. The only significant differences between disability PD groups were found for performances in the cognitive-motor hybrid (tracking) task, both in dual and triple conditions. Our results showed a better performance for the mild rather than for the moderate disability group in the single condition task and a significant decline of the mild disability group in the dual and triple condition when compared to the levels of those shown by the moderate disability group. The group-condition interaction remained significant when the cognitive status was statistically controlled. Conclusion. The hybrid of motor-cognitive task combining with a cognitive task (i. e., fluency) successfully differentiated between mild and moderate PD patients in the context of dual and triple multitask sets even when the cognitive status was statistically controlled. Our results highlight the importance of jointly measuring the complex interplay between motor and cognitive skills in PD.
Robust Feedback Control for Nonminimum Phase, Delayed, or Unstable Systems with Multiple Inputs
Authors: Gil-Martínez Montserrat , Rico-Azagra Javier
Published: April 2020

This paper presents a feedback control solution that achieves robust stability and disturbance rejection in systems with multiple manipulated inputs and a single measurable output. The uncertain plant models may exhibit either nonminimum phase, or delay, or unstable phenomena, which makes it not easy to take full advantage of the frequency response of each plant. In the framework of quantitative feedback theory (QFT), a methodology is proposed to decide the best control bandwidth distribution among inputs and to design the set of parallel controllers with as small as possible gain at each frequency. The temperature regulation in a continuous stirred-tank reactor (CSTR) illustrates the benefits of a quantitative frequency distribution of the dynamic controllability between the jacket flow and the feed flow. The main challenge is that the feed flow exhibits a higher temperature regulation capacity and also produces a temporary decrease in the reactor temperature (nonminimum phase behaviour).
Clinical Features of Type B Insulin Resistance in Japanese Patients: Case Report and Survey-Based Case Series Study
Authors: Hirota Yusuke , Suwanai Hirotsugu , Yamauchi Toshimasa , Kadowaki Takashi
Published: April 2020

Type B insulin resistance (TBIR) is an extremely rare disease characterized by marked hyperglycemia and insulin resistance and often coexists with autoimmune diseases. The characteristics, symptoms, blood glucose patterns, comorbidities, and treatments of TBIR all vary and are not defined. In this study, we described a case of TBIR that developed 6 months after DPP-4 inhibitor administration and immediately after the patient caught a cold. Treatment using prednisolone and insulin-like growth factor-1 was effective. We also conducted an observational survey-based case series study in a Japanese cohort comprising 21 cases. The average age of onset of TBIR was 62.3±14.8 (17–84) years, and 61.9% of subjects were male. The majority of patients (90.4%) were 50 years old and over. During the study period, there was a high percentage (85.7%) of episodes of hypoglycemia, which was the trigger for diagnosis in more than 50% of cases. Glycemic patterns included 7 cases of hyperglycemia (33.3%), 10 cases of hypoglycemia (47.6%), and 4 cases of both hyperglycemia and hypoglycemia (19.1%). In the hypoglycemic group, 90.0% of patients were male. Furthermore, 71.4% of cases were antinuclear antibody positive, and 81.0% of cases were complicated with autoimmune disease. Systemic lupus erythematosus (38.1%) and Sjögren’s syndrome (23.8%) were relatively common as coexisting autoimmune diseases. Treatment was based on prednisolone use, which was used in 88.9% of patients. On the other hand, the effect of IGF-1 was limited. Overall, the prognosis of TBIR was good.