bluuebunny/crossref_metadata_2025 huggingface dataset:
Dysprosium(III) and thulium(III) complexes of DO3A-monoanilides: an investigation of electronic effects on their relaxometric and amide-based PARACEST properties
Authors: Lewis Melissa M. , Milne Mark , Bartha Robert , Hudson Robert H.E.
Published: October 2014

A series of 1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate monoamide (DO3A-monoanilide) complexes Dy3+ and Tm3+ were prepared and their magnetic properties evaluated in the context of their potential use as pH sensors. The ligands varied by para-substitution of the aniline moiety and represent electron-withdrawing and electron-donating groups. Only the Tm3+ complexes produced chemical exchange saturation transfer (CEST) spectra with CEST intensities due to the amide proton ranging from 1% to 8%. A maximum CEST signal was observed under slightly alkaline conditions (pH ∼8) when electron-donating groups were present, whereas the strongly electron-withdrawing nitro group produced a maximum CEST at neutral pH (pH = 7). The T1 and T2 relaxivities of the Dy3+ and Tm3+ complexes were also assessed. The T1 relaxivities of the Dy3+ and Tm3+ complexes were both low (r1 ≤ 0.3 mM−1 s−1, 25 °C, pH = 7) but, as expected, the Dy3+ complexes had much higher T2 relaxivities (r2 = 2–7 mM−1 s−1, 25 °C, pH = 7) as compared to the Tm3+-based chelates (r2 ≤ 0.09 mM−1 s−1, 25 °C, pH = 7).
Mapping a knot by a continuous map
Authors: Taniyama Kouki
Published: October 2014

By a fixed continuous map from a 3-space to itself, a knot in the 3-space may be mapped to another knot in the 3-space. We analyze possible knot types of them. Then we map a knot repeatedly by a fixed continuous map and analyze possible infinite sequences of knot types.
AN EFFECTIVE APPROXIMATION FOR ZERO-COUPON BONDS AND ARROW–DEBREU PRICES IN THE BLACK–KARASINSKI MODEL
Authors: STEHLÍKOVÁ BEÁTA , CAPRIOTTI LUCA
Published: October 2014

We present an accurate and easy-to-compute approximation of zero-coupon bonds and Arrow–Debreu (AD) prices for the Black–Karasinski (BK) model of interest rates or default intensities. Through this procedure, dubbed exponent expansion, AD prices are obtained as a power series in time to maturity. This provides remarkably accurate results — for time horizons up to several years — even when truncated to the first few terms. For larger time horizons the exponent expansion can be combined with a fast numerical convolution to obtain extremely accurate results.
A Novel Forecasting Model Based on Support Vector Regression and Bat Meta-Heuristic (Bat–SVR): Case Study in Printed Circuit Board Industry
Authors: Tavakkoli Amirmohammad , Rezaeenour Jalal , Hadavandi Esmaeil
Published: October 2014

Sales forecasting is very beneficial to most businesses. A successful business needs accurate sales forecasting to understand the market and sales trends. This paper presents a novel sales forecasting model by integrating support vector regression (SVR) and bat algorithm (BA). Since the accuracy of SVR forecasting mainly depends on SVR parameters, we use BA for tuning these parameters because Bat is a newly introduced algorithm and has many parameters. In order to find the best set of BA parameters Taguchi method was utilized. We validated our model on four known UCI datasets. Then we applied our model in printed circuit board (PCB) sales forecasting case study. We compared the accuracy of the proposed model with Genetic algorithm (GA)–SVR, particle swarm optimization (PSO)–SVR, and classic-SVR. The experimental results show that the proposed model outperforms the others. To ensure the robustness of our proposed model, sensitivity analysis was also done using our model to find out the effects of dependent variables values on sales time series.
Global Sparse Analysis Framework
Authors: Oh Hakjoo , Heo Kihong , Lee Wonchan , Lee Woosuk , Park Daejun , Kang Jeehoon , Yi Kwangkeun
Published: October 2014

In this article, we present a general method for achieving global static analyzers that are precise and sound, yet also scalable. Our method, on top of the abstract interpretation framework, is a general sparse analysis technique that supports relational as well as nonrelational semantics properties for various programming languages. Analysis designers first use the abstract interpretation framework to have a global and correct static analyzer whose scalability is unattended. Upon this underlying sound static analyzer, analysis designers add our generalized sparse analysis techniques to improve its scalability while preserving the precision of the underlying analysis. Our method prescribes what to prove to guarantee that the resulting sparse version should preserve the precision of the underlying analyzer.

We formally present our framework and show that existing sparse analyses are all restricted instances of our framework. In addition, we show more semantically elaborate design examples of sparse nonrelational and relational static analyses. We then present their implementation results that scale to globally analyze up to one million lines of C programs. We also show a set of implementation techniques that turn out to be critical to economically support the sparse analysis process.
Mulsemedia
Authors: Ghinea Gheorghita , Timmerer Christian , Lin Weisi , Gulliver Stephen R.
Published: October 2014

Mulsemedia—multiple sensorial media—captures a wide variety of research efforts and applications. This article presents a historic perspective on mulsemedia work and reviews current developments in the area. These take place across the traditional multimedia spectrum—from virtual reality applications to computer games—as well as efforts in the arts, gastronomy, and therapy, to mention a few. We also describe standardization efforts, via the MPEG-V standard, and identify future developments and exciting challenges the community needs to overcome.
Wikidata
Authors: Vrandečić Denny , Krötzsch Markus
Published: October 2014

This collaboratively edited knowledgebase provides a common source of data for Wikipedia, and everyone else.
A Local Frequency Analysis of Light Scattering and Absorption
Authors: Belcour Laurent , Bala Kavita , Soler Cyril
Published: October 2014

Rendering participating media requires significant computation, but the effect of volumetric scattering is often eventually smooth. This article proposes an innovative analysis of absorption and scattering of local light fields in the Fourier domain and derives the corresponding set of operators on the covariance matrix of the power spectrum of the light field. This analysis brings an efficient prediction tool for the behavior of light along a light path in participating media. We leverage this analysis to derive proper frequency prediction metrics in 3D by combining per-light path information in the volume.

We demonstrate the use of these metrics to significantly improve the convergence of a variety of existing methods for the simulation of multiple scattering in participating media. First, we propose an efficient computation of second derivatives of the fluence, to be used in methods like irradiance caching. Second, we derive proper filters and adaptive sample densities for image-space adaptive sampling and reconstruction. Third, we propose an adaptive sampling for the integration of scattered illumination to the camera. Finally, we improve the convergence of progressive photon beams by predicting where the radius of light gathering can stop decreasing. Light paths in participating media can be very complex. Our key contribution is to show that analyzing local light fields in the Fourier domain reveals the consistency of illumination in such media and provides a set of simple and useful rules to be used to accelerate existing global illumination methods.
Toward Personalized Context Recognition for Mobile Users
Authors: Huai Baoxing , Chen Enhong , Zhu Hengshu , Xiong Hui , Bao Tengfei , Liu Qi , Tian Jilei
Published: October 2014

The problem of mobile context recognition targets the identification of semantic meaning of context in a mobile environment. This plays an important role in understanding mobile user behaviors and thus provides the opportunity for the development of better intelligent context-aware services. A key step of context recognition is to model the personalized contextual information of mobile users. Although many studies have been devoted to mobile context modeling, limited efforts have been made on the exploitation of the sequential and dependency characteristics of mobile contextual information. Also, the latent semantics behind mobile context are often ambiguous and poorly understood. Indeed, a promising direction is to incorporate some domain knowledge of common contexts, such as “waiting for a bus” or “having dinner,” by modeling both labeled and unlabeled context data from mobile users because there are often few labeled contexts available in practice. To this end, in this article, we propose a sequence-based semisupervised approach to modeling personalized context for mobile users. Specifically, we first exploit the Bayesian Hidden Markov Model (B-HMM) for modeling context in the form of probabilistic distributions and transitions of raw context data. Also, we propose a sequential model by extending B-HMM with the prior knowledge of contextual features to model context more accurately. Then, to efficiently learn the parameters and initial values of the proposed models, we develop a novel approach for parameter estimation by integrating the Dirichlet Process Mixture (DPM) model and the Mixture Unigram (MU) model. Furthermore, by incorporating both user-labeled and unlabeled data, we propose a semisupervised learning-based algorithm to identify and model the latent semantics of context. Finally, experimental results on real-world data clearly validate both the efficiency and effectiveness of the proposed approaches for recognizing personalized context of mobile users.
Efficiently Estimating Motif Statistics of Large Networks
Authors: Wang Pinghui , Lui John C. S. , Ribeiro Bruno , Towsley Don , Zhao Junzhou , Guan Xiaohong
Published: October 2014

Exploring statistics of locally connected subgraph patterns (also known as network motifs) has helped researchers better understand the structure and function of biological and Online Social Networks (OSNs). Nowadays, the massive size of some critical networks—often stored in already overloaded relational databases—effectively limits the rate at which nodes and edges can be explored, making it a challenge to accurately discover subgraph statistics. In this work, we propose
sampling methods
to accurately estimate subgraph statistics from as few queried nodes as possible. We present sampling algorithms that efficiently and accurately estimate subgraph properties of massive networks. Our algorithms require no precomputation or complete network topology information. At the same time, we provide theoretical guarantees of convergence. We perform experiments using widely known datasets and show that, for the same accuracy, our algorithms require an order of magnitude less queries (samples) than the current state-of-the-art algorithms.
Reading news with maps by exploiting spatial synonyms
Authors: Samet Hanan , Sankaranarayanan Jagan , Lieberman Michael D. , Adelfio Marco D. , Fruin Brendan C. , Lotkowski Jack M. , Panozzo Daniele , Sperling Jon , Teitler Benjamin E.
Published: October 2014

Use this map query interface to search the world, even when not sure what information you seek.
Continuity Transition with a Single Regular Curved-Knot Spline Surface
Authors: Shi Kan-Le , Yong Jun-Hai , Sun Jia-Guang , Paul Jean-Claude
Published: October 2014

We propose a specialized form of the curved-knot B-spline surface of Hayes [1982] that we call
regular curved-knot spline surface
. Unlike the original formulation where the knots of the first parametric coordinate can evolve arbitrarily with respect to the second coordinate, our formulation designs the knot functions as special curves that guarantee a monotonic blending of the knots corresponding to opposite surface boundaries. Furthermore, we demonstrate that local derivatives on the boundary can be described as an ordinary B-spline surface. The latter property allows for constructing smooth transitions between B-spline boundaries with different knot vectors.
EEG Correlates of Pleasant and Unpleasant Odor Perception
Authors: Kroupi Eleni , Yazdani Ashkan , Vesin Jean-Marc , Ebrahimi Touradj
Published: October 2014

Olfaction-enhanced multimedia experience is becoming vital for strengthening the sensation of reality and the quality of user experience. One approach to investigate olfactory perception is to analyze the alterations in brain activity during stimulation with different odors. In this article, the changes in the electroencephalogram (EEG) when perceiving hedonically-different odors are studied. Results of within and across-subject analysis are presented. We show that EEG-based odor classification using brain activity is possible and can be used to automatically recognize odor pleasantness when a subject-specific classifier is trained. However, it is a challenging problem to design a generic classifier.
Feel Effects
Authors: Israr Ali , Zhao Siyan , Schwalje Kaitlyn , Klatzky Roberta , Lehman Jill
Published: October 2014

Despite a long history of use in communication, haptic feedback is a relatively new addition to the toolbox of special effects. Unlike artists who use sound or vision, haptic designers cannot simply access libraries of effects that map cleanly to media content, and they lack even guiding principles for creating such effects. In this article, we make progress toward both capabilities: we generate a foundational library of usable haptic vocabulary and do so with a methodology that allows ongoing additions to the library in a principled and effective way. We define a
feel effect
as an explicit pairing between a meaningful linguistic phrase and a rendered haptic pattern. Our initial experiment demonstrates that users who have only their intrinsic language capacities, and no haptic expertise, can generate a core set of feel effects that lend themselves via semantic inference to the design of additional effects. The resulting collection of more than 40 effects covers a wide range of situations (including precipitation, animal locomotion, striking, and pulsating events) and is empirically shown to produce the named sensation for the majority of our test users in a second experiment. Our experiments demonstrate a unique and systematic approach to designing a vocabulary of haptic sensations that are related in both the semantic and parametric spaces.
A Generic Utility Model Representing the Quality of Sensory Experience
Authors: Rainer Benjamin , Timmerer Christian
Published: October 2014

Current QoE research is mainly focusing on single modalities (audio, visual) or combinations thereof. In our research, we propose annotating traditional multimedia content with additional sensory effects, such as ambient light, vibration, wind, and olfaction, which could potentially stimulate all human senses. Investigating the influence of individual sensory effects and combinations thereof is important in order to understand how these individual sensory effects influence the Quality of Experience (QoE) as a whole. In this article, we describe the results of such a subjective quality assessment of audio-visual sequences which are annotated with additional sensory effects such as ambient light, wind, and vibration using the MPEG-V standard. The results of this assessment allow us to derive a utility model representing the Quality of Sensory Experience (QuaSE) complementary to existing QoE models described in terms of Quality of Service (QoS) parameters. For validating our proposed utility model, we provide an example instantiation and validate it against results of subjective quality assessments.
“Wow! You Are So Beautiful Today!”
Authors: Liu Luoqi , Xing Junliang , Liu Si , Xu Hui , Zhou Xi , Yan Shuicheng
Published: October 2014

Beauty e-Experts, a fully automatic system for makeover recommendation and synthesis, is developed in this work. The makeover recommendation and synthesis system simultaneously considers many kinds of makeover items on hairstyle and makeup. Given a user-provided frontal face image with short/bound hair and no/light makeup, the Beauty e-Experts system not only recommends the most suitable hairdo and makeup, but also synthesizes the virtual hairdo and makeup effects. To acquire enough knowledge for beauty modeling, we built the Beauty e-Experts Database, which contains 1,505 female photos with a variety of attributes annotated with different discrete values. We organize these attributes into two different categories, beauty attributes and beauty-related attributes. Beauty attributes refer to those values that are changeable during the makeover process and thus need to be recommended by the system. Beauty-related attributes are those values that cannot be changed during the makeup process but can help the system to perform recommendation. Based on this Beauty e-Experts Dataset, two problems are addressed for the Beauty e-Experts system: what to recommend and how to wear it, which describes a similar process of selecting hairstyle and cosmetics in daily life. For the what-to-recommend problem, we propose a multiple tree-structured supergraph model to explore the complex relationships among high-level beauty attributes, mid-level beauty-related attributes, and low-level image features. Based on this model, the most compatible beauty attributes for a given facial image can be efficiently inferred. For the how-to-wear-it problem, an effective and efficient facial image synthesis module is designed to seamlessly synthesize the recommended makeovers into the user facial image. We have conducted extensive experiments on testing images of various conditions to evaluate and analyze the proposed system. The experimental results well demonstrate the effectiveness and efficiency of the proposed system.
Gradual evolution
Authors: Savage Neil
Published: October 2014

Dynamically typed languages adopt features of static typing to cope with growth.
Certificate transparency
Authors: Laurie Ben
Published: October 2014

Public, verifiable, append-only logs.
Outsourcing responsibility
Authors: Neville-Neil George V.
Published: October 2014

What do you do when your debugger fails you?
Tesseract
Authors: Arya Kapil , Baskakov Yury , Garthwaite Alex
Published: October 2014

Double-paging is an often-cited, if unsubstantiated, problem in multi-level scheduling of memory between virtual machines (VMs) and the hypervisor. This problem occurs when both a virtualized guest and the hypervisor overcommit their respective physical address-spaces. When the guest pages out memory previously swapped out by the hypervisor, it initiates an expensive sequence of steps causing the contents to be read in from the hypervisor swapfile only to be written out again, significantly lengthening the time to complete the guest I/O request. As a result, performance rapidly drops.

We present Tesseract, a system that directly and transparently addresses the double-paging problem. Tesseract tracks when guest and hypervisor I/O operations are redundant and modifies these I/Os to create indirections to existing disk blocks containing the page contents. Although our focus is on reconciling I/Os between the guest disks and hypervisor swap, our technique is general and can reconcile, or deduplicate, I/Os for guest pages read or written by the VM.

Deduplication of disk blocks for file contents accessed in a common manner is well-understood. One challenge that our approach faces is that the locality of guest I/Os (reflecting the guest's notion of disk layout) often differs from that of the blocks in the hypervisor swap. This loss of locality through indirection results in significant performance loss on subsequent guest reads. We propose two alternatives to recovering this lost locality, each based on the idea of asynchronously reorganizing the indirected blocks in persistent storage.

We evaluate our system and show that it can significantly reduce the costs of double-paging. We focus our experiments on a synthetic benchmark designed to highlight its effects. In our experiments we observe Tesseract can improve our benchmark's throughput by as much as 200% when using traditional disks and by as much as 30% when using SSD. At the same time worst case application responsiveness can be improved by a factor of 5.
Virtual asymmetric multiprocessor for interactive performance of consolidated desktops
Authors: Kim Hwanju , Kim Sangwook , Jeong Jinkyu , Lee Joonwon
Published: October 2014

This paper presents virtual asymmetric multiprocessor, a new scheme of virtual desktop scheduling on multi-core processors for user-interactive performance. The proposed scheme enables virtual CPUs to be dynamically performance-asymmetric based on their hosted workloads. To enhance user experience on consolidated desktops, our scheme provides interactive workloads with fast virtual CPUs, which have more computing power than those hosting background workloads in the same virtual machine. To this end, we devise a hypervisor extension that transparently classifies background tasks from potentially interactive workloads. In addition, we introduce a guest extension that manipulates the scheduling policy of an operating system in favor of our hypervisor-level scheme so that interactive performance can be further improved. Our evaluation shows that the proposed scheme significantly improves interactive performance of application launch, Web browsing, and video playback applications when CPU-intensive workloads highly disturb the interactive workloads.
Efficient memory virtualization for Cross-ISA system mode emulation
Authors: Chang Chao-Jui , Wu Jan-Jan , Hsu Wei-Chung , Liu Pangfeng , Yew Pen-Chung
Published: October 2014

Cross-ISA system-mode emulation has many important applications. For example, Cross-ISA system-mode emulation helps computer architects and OS developers trace and debug kernel execution-flow efficiently by emulating a slower platform (such as ARM) on a more powerful plat-form (such as an x86 machine). Cross-ISA system-mode emulation also enables workload consolidation in data centers with platforms of different instruction-set architectures (ISAs). However, system-mode emulation is much slower. One major overhead in system-mode emulation is the multi-level memory address translation that maps guest virtual address to host physical address. Shadow page tables (SPT) have been used to reduce such overheads, but primarily for same-ISA virtualization. In this paper we propose a novel approach called embedded shadow page tables (ESPT). EPST embeds a shadow page table into the address space of a cross-ISA dynamic binary translation (DBT) and uses hardware memory management unit in the CPU to translate memory addresses, instead of software translation in a current DBT emulator like QEMU. We also use the larger address space on modern 64-bit CPUs to accommodate our DBT emulator so that it will not interfere with the guest operating system. We incorporate our new scheme into QEMU, a popular, retargetable cross-ISA system emulator. SPEC CINT2006 benchmark results indicate that our technique achieves an average speedup of 1.51 times in system mode when emulating ARM on x86, and a 1.59 times speedup for emulating IA32 on x86_64.
A virtualized separation kernel for mixed criticality systems
Authors: Li Ye , West Richard , Missimer Eric
Published: October 2014

Multi- and many-core processors are becoming increasingly popular in embedded systems. Many of these processors now feature hardware virtualization capabilities, such as the ARM Cortex A15, and x86 processors with Intel VT-x or AMD-V support. Hardware virtualization offers opportunities to partition physical resources, including processor cores, memory and I/O devices amongst guest virtual machines. Mixed criticality systems and services can then co-exist on the same platform in separate virtual machines. However, traditional virtual machine systems are too expensive because of the costs of trapping into hypervisors to multiplex and manage machine physical resources on behalf of separate guests. For example, hypervisors are needed to schedule separate VMs on physical processor cores. In this paper, we discuss the design of the Quest-V separation kernel, which partitions services of different criticalities in separate virtual machines, or sandboxes. Each sandbox encapsulates a subset of machine physical resources that it manages without requiring intervention of a hypervisor. Moreover, a hypervisor is not needed for normal operation, except to bootstrap the system and establish communication channels between sandboxes.
Composable multi-level debugging with Stackdb
Authors: Johnson David , Hibler Mike , Eide Eric
Published: October 2014

Virtual machine introspection (VMI) allows users to debug software that executes within a virtual machine. To support rich, whole-system analyses, a VMI tool must inspect and control systems at multiple levels of the software stack. Traditional debuggers enable inspection and control, but they limit users to treating a whole system as just one kind of target: e.g., just a kernel, or just a process, but not both.

We created Stackdb, a debugging library with VMI support that allows one to monitor and control a whole system through multiple, coordinated targets. A target corresponds to a particular level of the system's software stack; multiple targets allow a user to observe a VM guest at several levels of abstraction simultaneously. For example, with Stackdb, one can observe a PHP script running in a Linux process in a Xen VM via three coordinated targets at the language, process, and kernel levels. Within Stackdb, higher-level targets are components that utilize lower-level targets; a key contribution of Stackdb is its API that supports multi-level and flexible "stacks" of targets. This paper describes the challenges we faced in creating Stackdb, presents the solutions we devised, and evaluates Stackdb through its application to a security-focused, whole-system case study.
Twitter analytics
Authors: Goonetilleke Oshini , Sellis Timos , Zhang Xiuzhen , Sathe Saket
Published: October 2014

With the inception of the Twitter microblogging platform in 2006, a myriad of research efforts have emerged studying different aspects of the Twittersphere. Each study exploits its own tools and mechanisms to capture, store, query and analyze Twitter data. Inevitably, platforms have been developed to replace this ad-hoc exploration with a more structured and methodological form of analysis. Another body of literature focuses on developing languages for querying Tweets. This paper addresses issues around the big data nature of Twitter and emphasizes the need for new data management and query language frameworks that address limitations of existing systems. We review existing approaches that were developed to facilitate twitter analytics followed by a discussion on research issues and technical challenges in developing integrated solutions.
What is Tumblr
Authors: Chang Yi , Tang Lei , Inagaki Yoshiyuki , Liu Yan
Published: October 2014

Tumblr, as one of the most popular microblogging platforms, has gained momentum recently. It is reported to have 166.4 millions of users and 73.4 billions of posts by January 2014. While many articles about Tumblr have been published in major press, there is not much scholar work so far. In this paper, we provide some pioneer analysis on Tumblr from a variety of aspects. We study the social network structure among Tumblr users, analyze its user generated content, and describe reblogging patterns to analyze its user behavior. We aim to provide a comprehensive statistical overview of Tumblr and compare it with other popular social services, including blogosphere, Twitter and Facebook, in answering a couple of key questions: What is Tumblr? How is Tumblr different from other social media networks? In short, we find Tumblr has more rich content than other microblogging platforms, and it contains hybrid characteristics of social networking, traditional blogosphere, and social media. This work serves as an early snapshot of Tumblr that later work can leverage.
New Methods in Tissue Engineering: Improved Models for Viral Infection
Authors: Ramanan Vyas , Scull Margaret A. , Sheahan Timothy P. , Rice Charles M. , Bhatia Sangeeta N.
Published: October 2014

New insights in the study of virus and host biology in the context of viral infection are made possible by the development of model systems that faithfully recapitulate the in vivo viral life cycle. Standard tissue culture models lack critical emergent properties driven by cellular organization and in vivo–like function, whereas animal models suffer from limited susceptibility to relevant human viruses and make it difficult to perform detailed molecular manipulation and analysis. Tissue engineering techniques may enable virologists to create infection models that combine the facile manipulation and readouts of tissue culture with the virus-relevant complexity of animal models. Here, we review the state of the art in tissue engineering and describe how tissue engineering techniques may alleviate some common shortcomings of existing models of viral infection, with a particular emphasis on hepatotropic viruses. We then discuss possible future applications of tissue engineering to virology, including current challenges and potential solutions.
Polydnaviruses: Nature's Genetic Engineers
Authors: Strand Michael R. , Burke Gaelen R.
Published: October 2014

Virus-host associations are usually viewed as parasitic, but several studies in recent years have reported examples of viruses that benefit host organisms. The Polydnaviridae are of particular interest because these viruses are all obligate mutualists of insects called parasitoid wasps. Parasitoids develop during their immature stages by feeding inside the body of other insects, which serve as their hosts. Polydnaviruses are vertically transmitted as proviruses through the germ line of wasps but also function as gene delivery vectors that wasps rely upon to genetically manipulate the hosts they parasitize. Here we review the evolutionary origin of polydnaviruses, the organization and function of their genomes, and some of their roles in parasitism.
Cytoplasmic RNA Granules and Viral Infection
Authors: Tsai Wei-Chih , Lloyd Richard E.
Published: October 2014

RNA granules are dynamic cellular structures essential for proper gene expression and homeostasis. The two principal types of cytoplasmic RNA granules are stress granules, which contain stalled translation initiation complexes, and processing bodies (P bodies), which concentrate factors involved in mRNA degradation. RNA granules are associated with gene silencing of transcripts; thus, viruses repress RNA granule functions to favor replication. This article discusses the breadth of viral interactions with cytoplasmic RNA granules, focusing on mechanisms that modulate the functions of RNA granules and that typically promote viral replication. Currently, mechanisms for virus manipulation of RNA granules can be loosely grouped into three nonexclusive categories: (a) cleavage of key RNA granule factors, (b) regulation of PKR activation, and (c) co-opting of RNA granule factors for new roles in viral replication. Viral modulation of RNA granules supports productive infection by inhibiting their gene-silencing functions and counteracting their role in linking stress sensing with innate immune activation.
(Invited) Spectroscopy of Deep Gap States in High-k Insulators
Authors: Afanas'ev Valery V , Wang Wan Chih , Cerbu Florin , Madia Oreste , Houssa Michel , Stesmans Andre
Published: October 2014

The work describes the physical principles of the exhaustive photodepopulation spectroscopy. This method allows one to determine the energy distribution of gap states in insulating materials using the observation of optically-assisted electron removal from the gap states in incremental spectral windows. Examples of the inferred energy distributions of acceptor-type electron states in several high-k oxide insulators (Al2O3, HfO2, GdxAl2-xO3) indicate that these are »1-2 eV broad. At the same time, no detectable density of donor states, expected to be present due to oxygen vacancies, is found in the studied oxides.
Effect of Al Doping on the Reliability of ALD HfO2
Authors: Bhuyian Mdnasiruddin , Misra Durga , Tapily Kandabara , Clark Robert , Consiglio Steve , Wajda Cory , Nakamura G. , Leusink Gert
Published: October 2014

This work has demonstrated a high quality HfO2 based gate stack by depositing atomic layer deposited (ALD) HfAlOx along with HfO2 in a layered structure. In order to get multifold enhancement of the gate stack quality both Al percentage and distribution were observed by varying the HfAlOx layer thickness and it was found that < 2% Al/(Al+Hf)% incorporation can result in up to 18% reduction in average EOT along with up to six fold reduction in gate leakage current as compared to the dielectric with no Al content. On the other hand, excess Al presence in the interfacial layer moderately increased the interface state density (Dit). When devices were stressed in the gate injection mode at a constant field stress dielectrics with Al/(Hf+Al)% ~ 2% showed resistance to stress induced flat-band voltage shift (DVFB), and stress induced leakage current (SILC). The time dependent dielectric breakdown (TDDB) characteristics of these devices showed a reduced charge to breakdown and an increase in the extracted Weibull slope (β) that further confirms an enhanced dielectric reliability.
(Invited) High Electron Mobility n-Channel Ge MOSFETs with Sub-Nm EOT
Authors: Toriumi Akira , Lee Choonghyun , Lu Cimang , Nishimura Tomonori
Published: October 2014

We demonstrate that Ge FETs show significantly high mobility of not only hole but also electron. In particular, this paper discusses what challenging issues are in n-channel FETs to achieve high electron mobility both in high electron density and in very thin EOT regions, by carefully considering electron scattering mechanisms in Ge MOS inversion channel. The results show us a promising future of Ge devices beyond Si FET technology.
(Invited) Interaction of Silicene and Germanene with Non-Metallic Substrates
Authors: Houssa Michel , Scalise Emilio , van den Broek Bas , Lu Augustin , Pourtois Geoffrey , Afanas'ev Valeri V. , Stesmans Andre
Published: October 2014

By using first-principles simulations, we investigate the interaction of silicene and germanene with various non-metallic substrates. We first consider weak van der Waals interactions between the 2D layers and dichalcogenide substrates, like MoX2 (X=S, Se, Te). The buckling of the silicene or germanene layer is correlated to the lattice mismatch between the 2D material and the MoX2 template. The electronic properties of silicene or germanene on these different templates then largely depend on the buckling of the 2D material layer: highly buckled silicene or germanene on MoS2 are predicted to be metallic, while low buckled silicene on MoTe2 is predicted to be semi-metallic, with preserved Dirac cones at the K points. We next study the covalent bonding of silicene and germanene on (0001) ZnS and ZnSe surfaces. On these substrates, silicene or germanene are found to be semiconducting. Remarkably, the nature and magnitude of their energy band gap can be controlled by an out-of-plane electric field.
(Invited) Doping, Functionalization, and Permeability of Graphene: Insights from First-Principles Studies
Authors: Tsetseris Leonidas , Wang Bin , Pantelides Sokrates T
Published: October 2014

Even though graphene is exceptional with respect to several physical properties, its use in electronic devices requires modification of the material. For example, development of graphene-based transistors necessitates the controlled increase of the number of charge carriers. Other applications may employ graphene chemical derivatives with enhanced functionalities. Here we review results from recent density-functional theory (DFT) studies on key processes that could dope or functionalize graphene. We demonstrate the crucial role carbon vacancies (single vacancies or double vacancies) can play in enabling substitutional doping and describe a vacancy-free doping scheme that employs the physisorption of ammonium groups. Finally, we show that graphene may be selectively permeable to certain atomic species, for example boron atoms.
Electrical Characteristics of Multilayer MoS2 Transistors at Real Operating Temperatures and Different Ambient Conditions
Authors: Kwon Hyuk-Jun , Jang Jaewon , Kang Hongki , Kim Sunkook , Subramanian Vivek , Grigoropoulos Costas P.
Published: October 2014

We describes the electrical characteristics of multilayer MoS2 thin film transistors (TFTs) through variable temperature measurement (from room temperature up to 350 K) and different operating ambients (in air and in a vacuum, ~10-5 Torr). Carrier transport mechanism was predicted through the observed temperature dependent electrical parameters (threshold voltage, field effect mobility, sub-threshold slope). Preliminary evidences were explained that the dominant transport mechanism of multilayer MoS2 TFTs could be the combination of the optical phonon scattering and thermionic emission depending on the working temperature. Furthermore, through additional low-frequency noise measurement, we supported the expectation that the multilayer MoS2 has better immunity than single-layer for the effect of chemisorption because multilayer MoS2 has relativley thick compared to Debye length where real carrier transportation occurs in the underlying channel.
(Invited) Investigation of Frenkel-Pair Formation in HfO2 and Its Influence on OxRAM Memory Reliability
Authors: Vianello Elisa , Blaise Philippe , Traoré Boubacar , Xue Kanhao , Fonseca Leonardo , Molas Gabriel , de Salvo Barbara , Perniola Luca , Nishi Yoshio
Published: October 2014

In this work we combine experimental data and first principles calculations to investigate the conductive filament (CF) creation in HfO2 based resistive switching memories. First, we propose that the CF in HfO2-based resistive OxRAMs is due to HfOx sub-oxides, possibly assuming a tetragonal symmetry with x≤1.5. Second, we demonstrate that Frenkel-Pair formation is favored by electron injection and by the adoption of oxygen reactive electrodes with low work function, such as Ti. Finally, endurance tests on a memory cell with Ti as the top electrode were performed to assess its cycling stability. Endurance up to 108 cycles with optimized set conditions has been demonstrated.
(Invited) Resistive Switching Characteristics and Controllable Quantized Conductance in Single-Crystal Anatase TiO2 on Si (001)
Authors: Yu Edward T. , Hu Chengqing , McDaniel Martin D. , Posadas Agham B. , Demkov Alexander A. , Ekerdt John G.
Published: October 2014

Resistive switching in single crystal anatase TiO2 grown by atomic layer deposition on Si (001) with an epitaxial single crystal SrTiO3 buffer layer is characterized and analyzed. Although switching occurs via a valence-change mechanism involving motion of oxygen vacancies, electrical characteristics highly reminiscent of electrochemical metallization memories – low leakage current in the high-resistance state, highly linear current-voltage characteristics in the low-resistance state, and a very high on/off current ratio – are observed. We postulate that these characteristics may be associated with formation of Ti
n
O2n-1 Magnéli or Magnéli-like nanophases in the low-resistance state. In addition, quantized conductance is observed in the low-resistance state, with the number of conducting ballistic channels being highly controllable via application of different compliance currents during the memory SET process. For compliance currents of 10-200µA, low resistance state conductances corresponding to 1 to 4 conductance channels, controllable to within a single quantum of conductance, are observed.
(Invited) The Interplay between Electronic and Ionic Transport in the Resistive Switching Process of Random Access Memory Devices
Authors: Magyari-Kope Blanka , Zhao Liang , Kamiya Katsumasa , Yang Moon Young , Niwa Masaaki , Shiraishi Kenji , Nishi Yoshio
Published: October 2014

The formation of conductive filamentary structures characteristic to the “ON” state (or LRS - low resistance state) of the resistance based memory devices were studied using ab initio simulation techniques. The atomistic description of the rupturing/dissolution process into the “OFF” state of the memory operation (HRS - high resistance state) was found to involve both ionic and electronic transport processes. Moreover, electron and hole trapping effects were shown to have a significant role in the switching process under applied electrical field. While hole injection into oxygen reduced transition metal oxides containing a formed filament can favor the dissolution process, electron injection induces filament formation. As possible ways to achieve improved device characteristics, preferential impurity doping in these types of systems is proposed to favorably affect and control the “ON” - “OFF” transition process.
(Invited) Ferroelectric Hafnium Oxide Based Materials and Devices: Assessment of Current Status and Future Prospects
Authors: Müller Johannes , Polakowski Patrick , Müller Stefan , Mikolajick Thomas
Published: October 2014

Bound to complex perovskite systems, ferroelectric random access memory (FRAM) suffers from limited CMOS-compatibility and faces severe scaling issues in today´s and future technology nodes. Nevertheless, compared to its current-driven non-volatile memory contenders, the field-driven FRAM excels in terms of low voltage operation and power consumption and therewith has managed to claim embedded as well as stand-alone niche markets. However, in order to overcome this restricted field of application, a material innovation is needed. With the ability to engineer ferroelectricity in HfO2, a high-k dielectric well established in memory and logic devices, a new material choice for improved manufacturability and scalability of future 1T and 1T-1C ferroelectric memories has emerged. This paper reviews the recent progress in this emerging field and critically assesses its current and future potential. Moreover, a general understanding of the thin film properties and stabilization mechanism of ferroelectric HfO2 will be given. Suitable memory concepts as well as new applications will be proposed accordingly.
(Invited) Stress-Induced Asymmetric Switching and Filament Instability in Electrochemical Memories
Authors: Ielmini Daniele , Ambrogio Stefano , Balatti Simone
Published: October 2014

Resistive switching memory based on electrochemical reaction are receiving a great interest as a future technology for nonvolatile storage class memories with fast programming and low power operation. To achieve scalable and reliable electrochemical memories, the switching and stability mechanisms must be carefully understood. This work shows that the switching characteristics of electrochemical memory devices display a strong asymmetric behavior, which is attributed to the mechanical stress around the conductive filament (CF) in the set state. CF instability after pulsed set is also evidenced and explained in terms of the compressive stress. Stress relaxation is shown to significantly stabilize ECM, thus providing new guidelines to improve memory stability at low set/reset power.
Fabrication and Physical Properties of Thin Films TiNx for Infrared Absorption
Authors: Jiang Bo , Dong Tao , He Yong , Yang Zhaochu , Su Yan , Wang Kaiying
Published: October 2014

This paper reports fabrication, electrical and optical characterization of TiNx thin films formed by reactive magnetron sputtering. The optimized resistivity of the films is applied to build a resonant structure for enhancing infrared absorptivity. The resistivity with 13% N2 at 200 °C is close to the theoretical value 377 Ω/square. The light absorptivity of a multilayer structure (TiNx/ SiNx/Al, SiNx/Al) has been recorded by Fourier Transform Infrared Spectroscopy (FTIR). A dramatic increase has been obtained as compared with the pristine SiNx. The offset of optimal sheet resistance is about 70 Ω/square compared to the theoretical value in the FTIR measurements. The thickness of TiNx and absorption of silicon nitride caused by Si-N vibration are major factors leading to the differences.
Ceramides mediate cigarette smoke-induced metabolic disruption in mice
Authors: Thatcher Mikayla O. , Tippetts Trevor S. , Nelson Michael B. , Swensen Adam C. , Winden Duane R. , Hansen Melissa E. , Anderson Madeline C. , Johnson Ian E. , Porter James P. , Reynolds Paul R. , Bikman Benjamin T.
Published: October 2014

Cigarette smoke exposure increases lung ceramide biosynthesis and alters metabolic function. We hypothesized that ceramides are released from the lung during cigarette smoke exposure and result in elevated skeletal muscle ceramide levels, resulting in insulin resistance and altered mitochondrial respiration. Employing cell and animal models, we explored the effect of cigarette smoke on muscle cell insulin signaling and mitochondrial respiration. Muscle cells were treated with conditioned medium from cigarette smoke extract (CSE)-exposed lung cells, followed by analysis of ceramides and assessment of insulin signaling and mitochondrial function. Mice were exposed to daily cigarette smoke and a high-fat, high-sugar (HFHS) diet with myriocin injections to inhibit ceramide synthesis. Comparisons were conducted between these mice and control animals on standard diets in the absence of smoke exposure and myriocin injections. Muscle cells treated with CSE-exposed conditioned medium were completely unresponsive to insulin stimulation, and mitochondrial respiration was severely blunted. These effects were mitigated when lung cells were treated with the ceramide inhibitor myriocin prior to and during CSE exposure. In mice, daily cigarette smoke exposure and HFHS diet resulted in insulin resistance, which correlated with elevated ceramides. Although myriocin injection was protective against insulin resistance with either smoke or HFHS, it was insufficient to prevent insulin resistance with combined CS and HFHS. However, myriocin injection restored muscle mitochondrial respiration in all treatments. Ceramide inhibition prevents metabolic disruption in muscle cells with smoke exposure and may explain whole body insulin resistance and mitochondrial dysfunction in vivo.