bluuebunny/crossref_metadata_2025 huggingface dataset:
NUMERICAL STUDY OF UNSTEADY SUPERCAVITATION PERTURBED BY A PRESSURE WAVE
Authors: ZHENG J. G. , KHOO B. C.
Published: June 2016

The unsteady features of supercavitation disturbed by an introduced pressure wave are investigated numerically using a one-fluid cavitation model. The supercavitating flow is assumed to be the homogeneous mixture of liquid and vapour which are locally under both kinetic and thermodynamic equilibrium. The compressibility effects of liquid water are taken into account to model the propagation of pressure wave through flow and its interaction with supercavitation bubble. The interaction between supercavity enveloping an underwater flat-nose cylinder and pressure wave is simulated and the resulting unsteady behavior of supercavitation is illustrated. It is observed that the supercavity will become unstable under the impact of the pressure wave and may collapse locally, which depends on the strength of perturbation. The huge pressure surge accompanying the collapse of supercavitation may cause the material erosion, noise, vibration and efficiency loss of operating underwater devices.
MODELLING AIR AND WATER TWO-PHASE ANNULAR FLOW IN A SMALL HORIZONTAL PIPE
Authors: YAO JUN , YAO YUFENG , ARINI ANTONINO , MCIIWAIN STUART , GORDON TIMOTHY
Published: June 2016

Numerical simulation using computational fluid dynamics (CFD) has been carried out to study air and water two-phase flow in a small horizontal pipe of an inner diameter of 8.8mm, in order to investigate unsteady flow pattern transition behaviours and underlying physical mechanisms. The surface liquid film thickness distributions, determined by either wavy or full annular flow regime, are shown in reasonable good agreement with available experimental data. It was demonstrated that CFD simulation was able to predict wavy flow structures accurately using two-phase flow sub-models embedded in ANSYS-Fluent solver of Eulerian–Eulerian framework, together with a user defined function subroutine ANWAVER-UDF. The flow transient behaviours from bubbly to annular flow patterns and the liquid film distributions revealed the presence of gas/liquid interferences between air and water film interface. An increase of upper wall liquid film thickness along the pipe was observed for both wavy annular and full annular scenarios. It was found that the liquid wavy front can be further broken down to form the water moisture with liquid droplets penetrating upwards. There are discrepancies between CFD predictions and experimental data on the liquid film thickness determined at the bottom and the upper wall surfaces, and the obtained modelling information can be used to assist further 3D user defined function subroutine development, especially when CFD simulation becomes much more expense to model full 3D two-phase flow transient performance from a wavy annular to a fully developed annular type.
MULTI-DISCIPLINARY DESIGN OPTIMIZATION OF HYPERSONIC AIR-BREATHING VEHICLE
Authors: WU PENG , TANG ZHILI , SHENG JIANDA
Published: June 2016

A 2D hypersonic vehicle shape with an idealized scramjet is designed at a cruise regime: Mach number (Ma) = 8.0, Angle of attack (AOA) = 0 deg and altitude ([Formula: see text]) = 30kms. Then a multi-objective design optimization of the 2D vehicle is carried out by using a Pareto Non-dominated Sorting Genetic Algorithm II (NSGA-II). In the optimization process, the flow around the air-breathing vehicle is simulated by inviscid Euler equations using FLUENT software and the combustion in the combustor is modeled by a methodology based on the well known combination effects of area-varying pipe flow and heat transfer pipe flow. Optimization results reveal tradeoffs among total pressure recovery coefficient of forebody, lift to drag ratio of vehicle, specific impulse of scramjet engine and the maximum temperature on the surface of vehicle.
FUTURE ENERGY BENCHMARK FOR DESALINATION: IS IT BETTER TO HAVE A POWER (ELECTRICITY) PLANT WITH RO OR MED/MSF?
Authors: SHAHZAD MUHAMMAD WAKIL , NG KIM CHOON , THU KYAW
Published: June 2016

Power and desalination cogeneration plants are common in many water scared courtiers. Designers and planners for cogeneration face tough challenges in deciding the options:- Is it better to operate a power plant (PP) with the reverse osmosis (i.e., PP+RO) or the thermally-driven multi-effect distillation/multi-stage flashed (PP+MED/MSF) methods. From literature, the RO methods are known to be energy efficient whilst the MED/MSF are known to have excellent thermodynamic synergies as only low pressure and temperature steam are used. Not with-standing the challenges of severe feed seawater of the Gulf, such as the frequent harmful algae blooms (HABs) and high silt contents, this presentation presents a quantitative analyses using the exergy and energetic approaches in evaluating the performances of a real cogeneration plant that was recently proposed in the eastern part of Saudi Arabia. We demonstrate that the process choice of PP+RO versus PP+MED depends on the inherent efficiencies of individual process method which is closely related to innovative process design. In this connection, a method of primary fuel cost apportionment for a co-generation plant with a MED desalination is presented. We show that an energy approach, that captures the quality of expanding steam, is a better method over the conventional work output (energetic) and the energy method seems to be over-penalizing a thermally-driven MED by as much as 22% in the operating cost of water.
An in-depth study of LTE
Authors: Huang Junxian , Qian Feng , Guo Yihua , Zhou Yuanyuan , Xu Qiang , Mao Z. Morley , Sen Subhabrata , Spatscheck Oliver
Published: June 2016

With lower latency and higher bandwidth than its predecessor 3G networks, the latest cellular technology 4G LTE has been attracting many new users. However, the interactions among applications, network transport protocol, and the radio layer still remain unexplored. In this work, we conduct an in-depth study of these interactions and their impact on performance, using a combination of active and passive measurements. We observed that LTE has significantly shorter state promotion delays and lower RTTs than those of 3G networks. We discovered various inefficiencies in TCP over LTE such as undesired slow start. We further developed a novel and lightweight passive bandwidth estimation technique for LTE networks. Using this tool, we discovered that many TCP connections significantly under-utilize the available bandwidth. On average, the actually used bandwidth is less than 50% of the available bandwidth. This causes data downloads to be longer, and incur additional energy overhead. We found that the under-utilization can be caused by both application behavior and TCP parameter setting. We found that 52.6% of all downlink TCP flows have been throttled by limited TCP receive window, and that data transfer patterns for some popular applications are both energy and network unfriendly. All these findings highlight the need to develop transport protocol mechanisms and applications that are more LTE-friendly.
Compressing IP forwarding tables
Authors: Rétvári Gábor , Tapolcai János , Kőrösi Attila , Majdán András , Heszberger Zalán
Published: June 2016

Lately, there has been an upsurge of interest in compressed data structures, aiming to pack ever larger quantities of information into constrained memory without sacrificing the efficiency of standard operations, like random access, search, or update. The main goal of this paper is to demonstrate how data compression can benefit the networking community, by showing how to squeeze the IP Forwarding Information Base (FIB), the giant table consulted by IP routers to make forwarding decisions, into information-theoretical entropy bounds, with essentially zero cost on longest prefix match and FIB update. First, we adopt the state-of-the-art in compressed data structures, yielding a static entropy-compressed FIB representation with asymptotically optimal lookup. Then, we re-design the venerable prefix tree, used commonly for IP lookup for at least 20 years in IP routers, to also admit entropy bounds and support lookup in optimal time and update in nearly optimal time. Evaluations on a Linux kernel prototype indicate that our compressors encode a FIB comprising more than 440K prefixes to just about 100--400 KBytes of memory, with a threefold increase in lookup throughput and no penalty on FIB updates.
Achieving high utilization with software-driven WAN
Authors: Hong Chi-Yao , Kandula Srikanth , Mahajan Ratul , Zhang Ming , Gill Vijay , Nanduri Mohan , Wattenhofer Roger
Published: June 2016

We present SWAN, a system that boosts the utilization of inter-datacenter networks by centrally controlling when and how much traffic each service sends and frequently re-configuring the network's data plane to match current traffic demand. But done simplistically, these re-configurations can also cause severe, transient congestion because different switches may apply updates at different times. We develop a novel technique that leverages a small amount of scratch capacity on links to apply updates in a provably congestion-free manner, without making any assumptions about the order and timing of updates at individual switches. Further, to scale to large networks in the face of limited forwarding table capacity, SWAN greedily selects a small set of entries that can best satisfy current demand. It updates this set without disrupting traffic by leveraging a small amount of scratch capacity in forwarding tables. Experiments using a testbed prototype and data-driven simulations of two production networks show that SWAN carries 60% more traffic than the current practice.
B4
Authors: Jain Sushant , Kumar Alok , Mandal Subhasree , Ong Joon , Poutievski Leon , Singh Arjun , Venkata Subbaiah , Wanderer Jim , Zhou Junlan , Zhu Min , Zolla Jon , Hölzle Urs , Stuart Stephen , Vahdat Amin
Published: June 2016

We present the design, implementation, and evaluation of B4, a private WAN connecting Google's data centers across the planet. B4 has a number of unique characteristics: i) massive bandwidth requirements deployed to a modest number of sites, ii) elastic traffic demand that seeks to maximize average bandwidth, and iii) full control over the edge servers and network, which enables rate limiting and demand measurement at the edge.

These characteristics led to a Software Defined Networking architecture using OpenFlow to control relatively simple switches built from merchant silicon. B4's centralized traffic engineering service drives links to near 100% utilization, while splitting application flows among multiple paths to balance capacity against application priority/demands. We describe experience with three years of B4 production deployment, lessons learned, and areas for future work.
TCP ex machina
Authors: Winstein Keith , Balakrishnan Hari
Published: June 2016

This paper describes a new approach to end-to-end congestion control on a multi-user network. Rather than manually formulate each endpoint's reaction to congestion signals, as in traditional protocols, we developed a program called Remy that generates congestion-control algorithms to run at the endpoints.

In this approach, the protocol designer specifies their prior knowledge or assumptions about the network and an objective that the algorithm will try to achieve, e.g., high throughput and low queueing delay. Remy then produces a distributed algorithm---the control rules for the independent endpoints---that tries to achieve this objective.

In simulations with ns-2, Remy-generated algorithms outperformed human-designed end-to-end techniques, including TCP Cubic, Compound, and Vegas. In many cases, Remy's algorithms also outperformed methods that require intrusive in-network changes, including XCP and Cubic-over-sfqCoDel (stochastic fair queueing with CoDel for active queue management).

Remy can generate algorithms both for networks where some parameters are known tightly a
priori
, e.g. datacenters, and for networks where prior knowledge is less precise, such as cellular networks. We characterize the sensitivity of the resulting performance to the specificity of the prior knowledge, and the consequences when real-world conditions contradict the assumptions supplied at design-time.
ElasticSwitch
Authors: Popa Lucian , Yalagandula Praveen , Banerjee Sujata , Mogul Jeffrey C. , Turner Yoshio , Santos Jose Renato
Published: June 2016

While cloud computing providers offer guaranteed allocations for resources such as CPU and memory, they do not offer any guarantees for network resources. The lack of network guarantees prevents tenants from predicting lower bounds on the performance of their applications. The research community has recognized this limitation but, unfortunately, prior solutions have significant limitations: either they are inefficient, because they are not work-conserving, or they are impractical, because they require expensive switch support or congestion-free network cores.

In this paper, we propose ElasticSwitch, an efficient and practical approach for providing bandwidth guarantees. ElasticSwitch is efficient because it utilizes the spare bandwidth from unreserved capacity or underutilized reservations. ElasticSwitch is practical because it can be fully implemented in hypervisors, without requiring a specific topology or any support from switches. Because hypervisors operate mostly independently, there is no need for complex coordination between them or with a central controller. Our experiments, with a prototype implementation on a 100-server testbed, demonstrate that ElasticSwitch provides bandwidth guarantees and is work-conserving, even in challenging situations.
Dhwani
Authors: Nandakumar Rajalakshmi , Chintalapudi Krishna Kant , Padmanabhan Venkat , Venkatesan Ramarathnam
Published: June 2016

Near Field Communication (NFC) enables physically proximate devices to communicate over very short ranges in a peer-to-peer manner without incurring complex network configuration overheads. However, adoption of NFC-enabled applications has been stymied by the low levels of penetration of NFC hardware. In this paper, we address the challenge of enabling NFC-like capability on the existing base of mobile phones. To this end, we develop Dhwani, a novel, acoustics-based NFC system that uses the microphone and speakers on mobile phones, thus eliminating the need for any specialized NFC hardware. A key feature of Dhwani is the JamSecure technique, which uses self-jamming coupled with self-interference cancellation at the receiver, to provide an information-theoretically secure communication channel between the devices. Our current implementation of Dhwani achieves data rates of up to 2.4 Kbps, which is sufficient for most existing NFC applications.
Lessons learned from the netsense smartphone study
Authors: Striegel Aaron , Liu Shu , Meng Lei , Poellabauer Christian , Hachen David , Lizardo Omar
Published: June 2016

Over the past few years, smartphones have emerged as one of the most popular mechanisms for accessing content across the Internet driving considerable research to improve wireless performance. A key foundation for such research efforts is the proper understanding of user behavior. However, the gathering of live smartphone data at scale is often difficult and expensive. The focus of this paper is to explore the lessons learned from a two year study of two hundred smart phone users at the University of Notre Dame. In this paper, we offer commentary with regards to the entire process of the study covering aspects including funding considerations, technical architecture design, lessons learned, and recommendations for future efforts gathering live user data.
Whole-home gesture recognition using wireless signals (demo)
Authors: Pu Qifan , Jiang Siyu , Gollakota Shyamnath
Published: June 2016

This demo presents WiSee, a novel human-computer interaction system that leverages wireless networks (e.g., Wi-Fi), to enable sensing and recognition of human gestures and motion. Since wire- less signals do not require line-of-sight and can traverse through walls, WiSee enables novel human-computer interfaces for remote device control and building automation. Further, it achieves this goal without requiring instrumentation of the human body with sensing devices. We integrate WiSee with applications and demonstrate how WiSee enables users to use gestures and control applications including music players and gaming systems. Specifically, our demo will allow SIGCOMM attendees to control a music player and a lighting control device using gestures.
AutoEmbed
Authors: Dietrich David , Rizk Amr , Papadimitriou Panagiotis
Published: June 2016

We present AutoEmbed, a fully-automated framework for VN embedding across multiple substrate networks. To automate VN embedding, AutoEmbed deploys functions over three layers: (i) Service Providers, (ii) VN Providers, and (iii) Infrastructure Providers (InPs). AutoEmbed enables VN Providers to partition VN requests among multiple substrate networks based on resource and network topology information that is not treated as confidential by InPs.

Subsequently, each VN segment is mapped by the corresponding InP onto its substrate network. AutoEmbed enables the evaluation of various aspects of multi-provider VN embedding, such as the efficiency and scalability of embedding algorithms, the impact of different levels of information disclosure on VN embedding efficiency, and the suitability of VN request specifications.
Qphone
Authors: Liu Bo , Zhao Baokang , Wei Ziling , Wu Chunqing , Su Jinshu , Yu Wanrong , Wang Fei , Sun Shihai
Published: June 2016

This work presents a novel quantum security VoIP phone, called Qphone. Qphone integrates quantum key distribution (QKD) and VoIP steganography, and achieves peer-to-peer communication with information-theoretical security (ITS) guaranteeing. Qphone consists of three parts, a real-time QKD system, RT-QKD, a steganography software, VS-Phone, and an audio encryption and authentication hardware, AE-KEY. RT-QKD explores QKD technologies, and is able establish a shared key between two peers ensuring ITS. VS-Phone utilizes VoIP steganography to protect transmission channels of sensitive information. Qphone can provide efficient and real-time security protections to meet different security demands.
Application-awareness in SDN
Authors: Qazi Zafar Ayyub , Lee Jeongkeun , Jin Tao , Bellala Gowtham , Arndt Manfred , Noubir Guevara
Published: June 2016

We present a framework,
Atlas
, which incorporates application-awareness into Software-Defined Networking (SDN), which is currently capable of L2/3/4-based policy enforcement but agnostic to higher layers.
Atlas
enables fine-grained, accurate and scalable application classification in SDN. It employs a machine learning (ML) based traffic classification technique, a crowd-sourcing approach to obtain ground truth data and leverages SDN's data reporting mechanism and centralized control. We prototype
Atlas
on HP Labs wireless networks and observe 94% accuracy on average, for top 40 Android applications.
Cloud3DView
Authors: Yin Jianxiong , Sun Peng , Wen Yonggang , Gong Haigang , Liu Ming , Li Xuelong , You Haipeng , Gao Jinqi , Lin Cynthia
Published: June 2016

The emergence of cloud computing has promoted growing demand and rapid deployment of data centers. However, data center operations require a set of sophisticated skills (e.g., command-line-interface), resulting in a high operational cost. In this demo, to reduce the data center operational cost, we design and build a novel cloud data center management system, based on the concept of 3D gamification. In particular, we apply data visualization techniques to overlay operational status upon a data center 3D model, allowing the operators to monitor the real-time situation and control the data center from a friendly user interface. This demo highlights: (1)a data center 3D view from a First Person Shooter (FPS) camera, (2)a run-time presentation of visualized infrastructures information. Moreover, to improve the user experience, we employ cutting-edge HCI technologies from multi-touch, for remote access to Cloud3DView.
TerraNNI
Authors: Agarwal Pankaj K. , Beutel Alex , Mølhave Thomas
Published: June 2016

With modern focus on remote sensing technology, such as LiDAR, the amount of spatial data, in the form of massive point clouds, has increased dramatically. Furthermore, repeated surveys of the same areas are becoming more common. This trend will only increase as topographic changes prompt surveys over already scanned areas, in which case we obtain large spatiotemporal datasets.

An initial step in the analysis of such spatial data is to create a digital elevation model representing the terrain, possibly over time. In the case of spatial (spatiotemporal, respectively) datasets, these models often represent elevation on a 2D (3D, respectively) grid. This involves interpolating the elevation of LiDAR points on these grid points.

In this article, we show how to efficiently perform natural neighbor interpolation over a 2D and 3D grid. Using a graphics processing unit (GPU), we describe different algorithms to attain speed and GPU-memory tradeoffs. Our experimental results demonstrate that our algorithms not only are significantly faster than earlier ones but also scale to much bigger datasets that previous algorithms were unable to handle.
An Efficient External Memory Algorithm for Terrain Viewshed Computation
Authors: Ferreira Chaulio R. , Andrade Marcus V. A. , Magalhães Salles V. G. , Franklin W. Randolph
Published: June 2016

This article presents T
iled
VS, a fast external algorithm and implementation for computing viewsheds. T
iled
VS is intended for terrains that are too large for internal memory, even more than 100,000×100,000 points. It subdivides the terrain into tiles that are stored compressed on disk and then paged into memory with a custom cache data structure and least recently used algorithm. If there is sufficient available memory to store a whole row of tiles, which is easy, then this specialized data management is faster than relying on the operating system’s virtual memory management. Applications of viewshed computation include siting radio transmitters, surveillance, and visual environmental impact measurement.

T
iled
VS runs a rotating line of sight from the observer to points on the region boundary. For each boundary point, it computes the visibility of all terrain points close to the line of sight. The running time is linear in the number of points. No terrain tile is read more than twice. T
iled
VS is very fast, for instance, processing a 104,000×104,000 terrain on a modest computer with only 512MB of RAM took only 1½ hours. On large datasets, T
iled
VS was several times faster than competing algorithms, such as the ones included in GRASS. The source code of T
iled
VS is freely available for nonprofit researchers to study, use, and extend.

A preliminary version of this algorithm appeared in a four-page ACM SIGSPATIAL GIS 2012 conference paper, “More Efficient Terrain Viewshed Computation on Massive Datasets Using External Memory.” This more detailed version adds the fast lossless compression stage that reduces the time by 30% to 40%, and many more experiments and comparisons.
Welcome to AI Matters, volume 2, issue 3
Authors: Eaton Eric , McGovern Amy
Published: June 2016

For the next two issues, we will be featuring
abstracts of recent doctoral theses
related to AI. We've assembled a diverse collection of dissertation abstracts, highlighting the excellent work done by doctoral students around the globe. In fact, we collected so many abstracts that we couldn't fit them into just one issue, so stay tuned for the second part of this collection later this summer. And, to see even more current doctoral research, be sure to stop by one of the doctoral consortia at the summer AI conferences (IJCAI, CVPR, ICAPS, etc).
Contextual test
Authors: Koren Oded , Perel Nir
Published: June 2016

The Imitation Game that was presented by Turing back in the 1950s was an important experiment whose purpose was to provide a basic platform for the question of whether a computer can think. Over the years other views were raised that presented weaknesses of and claims against Turing's test, and some alternative tests were even proposed and recently there is a claim that a program already passes Turing Test. The ability to interface with a huge amount of data from a variety of public resources over the internet creates new functionalities and capabilities that may allow updating of the test rules, modifying them (based on examples, that at least part of them are already implemented) and also changing the scope of the question from whether a computer can think to how relevant the answer is to the requester.
Neighborhood graph construction for semi-supervised learning
Authors: Berton Lilian , de Andrade Lopes Alneu
Published: June 2016

Semi-supervised learning (SSL) is useful when few labeled and plenty of unlabeled examples are available. This occurs in most of the cases due to labeled instances be difficult, expensive and time consuming to be obtained since human experts are required for the labeling task (Chapelle, Schlkopf, & Zien, 2010). The training set contain labeled data represented by

X
L

= {(

x
1
, y
1

) ... (

x
1
, y
1

)}, and unlabelled data represented as

X
U

= {

x
l+1
... x
l+u

}. The total amount of training data is
X
=
l ∪ u
. The set of labeled examples is associated with the labels

L
Y

= {
y
1
, ...,
y
l
} where
y
i
ε {1,...,
c
} and
c
is the number of classes. The purpose of SSL is to infer the missing labels

Y
U

= {

y
l+1

,...,

y
n

} corresponding to the unlabelled set

X
U

.
Wow! that looks strange
Authors: Saleh Babak
Published: June 2016

We study various types of atypicalities in images by proposing a new dataset of abnormal images, extracting a list of reasons of atypicality, enumerating distinct modes or types of abnormal images, and deriving computational models motivated by human-level reasoning.
Online machine learning for networked data
Authors: Ghosh Shaona
Published: June 2016

Networked data are ubiquitous in this era of the social, economical and technological revolution resting on the backbone of the internet. With the spread of mobile phones, sensors, embedded devices and industrial robots, the ability to collect and generate interdependent data is on an all time high. This enormity of data is supplemented with social networks like Facebook, Tumblr, LinkedIn, Twitter and many others, that connect people around the globe as a network, allowing them to share the data they collect, generate or distribute, in real-time. Further, with the 'Internet of things', appliances, vehicles and wearable technological devices can communicate with each other. The resulting trend is better and bigger ways of "collecting, creating, managing and storing of data" also known as Big Data (White House, 2014). Most often, such big data capture a rich structure of inter-relationships, resulting in either an extrinsic graphical pattern as in social and sensor networks or dependencies that can be modelled as a graph, like neighbouring pixels sharing similar intensities, in real-time 3D scene capture images from the autonomous vehicle cameras. More often, the nature of such data is such that it is streamed in real-time from multiple sources as in the case of the network of sensors. The data has a sequential nature as seen in product recommendation based on the user clickthrough rate. The data is dynamic as in the case of evolving blog communities or shifting in pattern as often seen in the example of trending tweets. In reality, even with the abundance of data, only a small percentage of it has available labelled information or annotation that can be used to model and categorize the vast quantities of unlabelled data. Naturally, the questions that arise are: how to program computers to automatically learn the underlying model and predict on the fly from streaming data? How does the computer algorithm capture the sequential nature of events? Further, more complex questions are can the algorithms guarantee that they will be efficient regardless of any sequence of data they see, in any order? Are these methods adaptive enough to predict based on dynamic real-time changes or how can the algorithms learn the unknown labels from the few available labels for very large and sparse networked data?
A fully GIS-integrated simulation approach for analyzing the spread of epidemics in urban areas
Authors: Haddad Hedi , Moulin Bernard , Thériault Marius
Published: June 2016

Human-to-human communicable diseases can be devastating in urban areas where large heterogeneous population groups are living in restricted spaces, causing serious concerns for public health, especially during epidemic outbreaks. Even though Geographic Information Systems (GIS) have been used to study a variety of public health issues in the last decade, their use to study human communicable diseases has been limited to the development of disease clustering, mapping and surveillance systems. These systems don't provide ways to understand and predict the dynamics of diseases spread across an urban region, taking into account the dynamics of human contacts and mobility, which are the main widely recognized mechanisms responsible for diseases' spread. In this paper we address such limits by presenting a GIS-based spatial-temporal simulation approach and software to support public health decision making in the context of communicable diseases in urban areas. The approach fully integrates epidemiological, mobility and GIS-data models at an aggregate population level in order to support spatialized interventions.
IWCTS 2015 workshop report: the Eighth ACM SIGSPATIAL International Workshop on International Workshop on Computational Transportation Science Seattle, Washington, USA - November 3, 2015
Authors: Huang Yan , Chen Xin
Published: June 2016

In the near future, vehicles, travelers, and the infrastructure will collectively have billions of sensors that can communicate with each other. Transportation systems, due to their distributed/mobile nature, can become the ultimate test-bed for a ubiquitous (i.e., embedded, highly-distributed, and sensor-laden) computing environment of unprecedented scale. This environment will enable numerous novel applications and order of magnitude improvement of the performance of existing applications. Information technology is the foundation for implementing new strategies, particularly if they are to be made available in real-time to wireless devices in vehicles or in the hands of people. Contributing are increasingly more sophisticated geospatial and spatio-temporal information management capabilities. Human factors, technology adoption and use, user feedback and incentives for collaborative behaviour are areas of technology policy central to the success of this ubiquitous computing environment.
Virtual cursors to enhance web accessibility for people with limited dexterity
Authors: Pérez J. Eduardo , Arrue Myriam
Published: June 2016

Basic web interactions, such as pointing and clicking links with an on-screen cursor, can be highly challenging for people with a lack of dexterity in their hands or arms. Much research has been done on studying point and click interactions, but most of this has focused mainly on able-bodied people interacting with standard pointing devices. In this paper, we present the design and the usability evaluation of two virtual cursors for assisting motor-impaired users when pointing and clicking links while browsing the Web. Results of a usability study involving nine motor-impaired and six able-bodied users applying their usual pointing device in a web-based experiment are presented. According to their self-reported assessments, the results show the acceptance and usefulness of both virtual cursors compared to the original unassisted one, underlining the importance of providing motor-impaired people with virtual enhancements to improve their web browsing ability.
Towards screen readers with concurrent speech
Authors: Guerreiro João
Published: June 2016

Blind people rely mostly on the auditory feedback of screen readers to consume digital information. Despite the browsing strategies employed by blind users [3], how fast can information be processed remains a major problem. Sighted people use scanning as a strategy to achieve this goal, by glancing at all content expecting to identify information of interest to be subsequently analyzed with further care. In contrast, screen readers rely on a sequential auditory channel that is impairing a quicker overview of the content, when compared to the visual presentation on screen.
Chamber-specific differences in human cardiac fibroblast proliferation and responsiveness toward simvastatin
Authors: Rizvi Farhan , DeFranco Alessandra , Siddiqui Ramail , Negmadjanov Ulugbek , Emelyanova Larisa , Holmuhamedov Alisher , Ross Gracious , Shi Yang , Holmuhamedov Ekhson , Kress David , Tajik A. Jamil , Jahangir Arshad
Published: June 2016

Fibroblasts, the most abundant cells in the heart, contribute to cardiac fibrosis, the substrate for the development of arrythmogenesis, and therefore are potential targets for preventing arrhythmic cardiac remodeling. A chamber-specific difference in the responsiveness of fibroblasts from the atria and ventricles toward cytokine and growth factors has been described in animal models, but it is unclear whether similar differences exist in human cardiac fibroblasts (HCFs) and whether drugs affect their proliferation differentially. Using cardiac fibroblasts from humans, differences between atrial and ventricular fibroblasts in serum-induced proliferation, DNA synthesis, cell cycle progression, cyclin gene expression, and their inhibition by simvastatin were determined. The serum-induced proliferation rate of human atrial fibroblasts was more than threefold greater than ventricular fibroblasts with faster DNA synthesis and higher mRNA levels of cyclin genes. Simvastatin predominantly decreased the rate of proliferation of atrial fibroblasts, with inhibition of cell cycle progression and an increase in the G0/G1 phase in atrial fibroblasts with a higher sensitivity toward inhibition compared with ventricular fibroblasts. The DNA synthesis and mRNA levels of cyclin A, D, and E were significantly reduced by simvastatin in atrial but not in ventricular fibroblasts. The inhibitory effect of simvastatin on atrial fibroblasts was abrogated by mevalonic acid (500 μM) that bypasses 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibition. Chamber-specific differences exist in the human heart because atrial fibroblasts have a higher proliferative capacity and are more sensitive to simvastatin-mediated inhibition through HMG-CoA reductase pathway. This mechanism may be useful in selectively preventing excessive atrial fibrosis without inhibiting adaptive ventricular remodeling during cardiac injury.
Ubiquitin-dependent and independent roles of SUMO in proteostasis
Authors: Liebelt Frauke , Vertegaal Alfred C. O.
Published: June 2016

Cellular proteomes are continuously undergoing alterations as a result of new production of proteins, protein folding, and degradation of proteins. The proper equilibrium of these processes is known as proteostasis, implying that proteomes are in homeostasis. Stress conditions can affect proteostasis due to the accumulation of misfolded proteins as a result of overloading the degradation machinery. Proteostasis is affected in neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, and multiple polyglutamine disorders including Huntington's disease. Owing to a lack of proteostasis, neuronal cells build up toxic protein aggregates in these diseases. Here, we review the role of the ubiquitin-like posttranslational modification SUMO in proteostasis. SUMO alone contributes to protein homeostasis by influencing protein signaling or solubility. However, the main contribution of SUMO to proteostasis is the ability to cooperate with, complement, and balance the ubiquitin-proteasome system at multiple levels. We discuss the identification of enzymes involved in the interplay between SUMO and ubiquitin, exploring the complexity of this crosstalk which regulates proteostasis. These enzymes include SUMO-targeted ubiquitin ligases and ubiquitin proteases counteracting these ligases. Additionally, we review the role of SUMO in brain-related diseases, where SUMO is primarily investigated because of its role during formation of aggregates, either independently or in cooperation with ubiquitin. Detailed understanding of the role of SUMO in these diseases could lead to novel treatment options.
Direct real-time quantification of mitochondrial oxidative phosphorylation efficiency in permeabilized skeletal muscle myofibers
Authors: Lark Daniel S. , Torres Maria J. , Lin Chien-Te , Ryan Terence E. , Anderson Ethan J. , Neufer P. Darrell
Published: June 2016

Oxidative phosphorylation (OXPHOS) efficiency, defined as the ATP-to-O ratio, is a critical feature of mitochondrial function that has been implicated in health, aging, and disease. To date, however, the methods to measure ATP/O have primarily relied on indirect approaches or entail parallel rather than simultaneous determination of ATP synthesis and O2 consumption rates. The purpose of this project was to develop and validate an approach to determine the ATP/O ratio in permeabilized fiber bundles (PmFBs) from simultaneous measures of ATP synthesis ( JATP) and O2 consumption ( JO2) rates in real time using a custom-designed apparatus. JO2 was measured via a polarigraphic oxygen sensor and JATP via fluorescence using an enzyme-linked assay system (hexokinase II, glucose-6-phosphate dehydrogenase) linked to NADPH production. Within the dynamic linear range of the assay system, ADP-stimulated increases in steady-state JATP mirrored increases in steady-state JO2 ( r2 = 0.91, P < 0.0001, n = 57 data points). ATP/O ratio was less than one under low rates of respiration (15 μM ADP) but increased to more than two at moderate (200 μM ADP) and maximal (2,000 μM ADP) rates of respiration with an interassay coefficient of variation of 24.03, 16.72, and 11.99%, respectively. Absolute and relative (to mechanistic) ATP/O ratios were lower in PmFBs (2.09 ± 0.251, 84%) compared with isolated mitochondria (2.44 ± 0.124, 98%). ATP/O ratios in PmFBs were not affected by the activity of adenylate kinase or creatine kinase. These findings validate an enzyme-linked respiratory clamp system for measuring OXPHOS efficiency in PmFBs and provide evidence that OXPHOS efficiency increases as energy demand increases.
Fine-tuning autophagy: from transcriptional to posttranslational regulation
Authors: Botti-Millet Joëlle , Nascimbeni Anna Chiara , Dupont Nicolas , Morel Etienne , Codogno Patrice
Published: June 2016

Macroautophagy (hereafter called autophagy) is a vacuolar lysosomal pathway for degradation of intracellular material in eukaryotic cells. Autophagy plays crucial roles in tissue homeostasis, in adaptation to stress situations, and in immune and inflammatory responses. Alteration of autophagy is associated with cancer, diabetes and obesity, cardiovascular disease, neurodegenerative disease, autoimmune disease, infection, and chronic inflammatory disease. Autophagy is controlled by autophagy-related (ATG) proteins that act in a coordinated manner to build up the initial autophagic vacuole named the autophagosome. It is now known that the activities of ATG proteins are modulated by posttranslational modifications such as phosphorylation, ubiquitination, and acetylation. Moreover, transcriptional and epigenetic controls are involved in the regulation of autophagy in stress situations. Here we summarize and discuss how posttranslational modifications and transcriptional and epigenetic controls regulate the involvement of autophagy in the proteostasis network.
PanIN-associated pericyte, glial, and islet remodeling in mice revealed by 3D pancreatic duct lesion histology
Authors: Lin Pei-Yu , Peng Shih-Jung , Shen Chia-Ning , Pasricha Pankaj J. , Tang Shiue-Cheng
Published: June 2016

Pericytes and glial cells are accessory cells of neurovascular networks, which have been reported to participate in scar formation after tissue injury. However, it remains unclear whether similar reactive cellular responses occur in pancreatic intraepithelial neoplasia (PanIN). In this study we developed three-dimensional (3D) duct lesion histology to investigate PanIN and the associated pericyte, glial, and islet remodeling. Transparent mouse pancreata with a KrasG12D mutation were used to develop 3D duct lesion histology. Deep-tissue, tile-scanning microscopy was performed to generate panoramic views of the diseased pancreas for global examination of early stage and advanced duct lesion formation. Fluorescence signals of ductal and neurovascular networks were simultaneously detected to reveal associated remodeling. Significantly, in KrasG12D-mutant mice, when the low-grade PanINs emerge, duct lesions appear as epithelial buds with perilesional pericyte and glial activation. When PanINs occur in large scale (induced by cerulein injections to the mutant mice), the 3D image data identifies 1) aggregation of PanINs in clusters in space; 2) overexpression of the pericyte marker NG2 in the PanIN microenvironment; and 3) epithelial in-growth to islets, forming the PanIN-islet complexes. Particularly, the PanIN-islet complexes associate with proliferating epithelial and stromal cells and receive substantial neurovascular supplies, making them landmarks in the atrophic lobe. Overall, perilesional pericyte and glial activation and formation of the PanIN-islet complex underline cellular heterogeneity in the duct lesion microenvironment. The results also illustrate the advantage of using 3D histology to reveal previously unknown details of neurovascular and endocrine links to the disease.
Podocyte injury: the role of proteinuria, urinary plasminogen, and oxidative stress
Authors: Raij Leopoldo , Tian Runxia , Wong Jenny S. , He John C. , Campbell Kirk N.
Published: June 2016

Podocytes are the key target for injury in proteinuric glomerular diseases that result in podocyte loss, progressive focal segmental glomerular sclerosis (FSGS), and renal failure. Current evidence suggests that the initiation of podocyte injury and associated proteinuria can be separated from factors that drive and maintain these pathogenic processes leading to FSGS. In nephrotic urine aberrant glomerular filtration of plasminogen (Plg) is activated to the biologically active serine protease plasmin by urokinase-type plasminogen activator (uPA). In vivo inhibition of uPA mitigates Plg activation and development of FSGS in several proteinuric models of renal disease including 5/6 nephrectomy. Here, we show that Plg is markedly increased in the urine in two murine models of proteinuric kidney disease associated with podocyte injury: Tg26 HIV-associated nephropathy and the Cd2ap−/−model of FSGS. We show that human podocytes express uPA and three Plg receptors: uPAR, tPA, and Plg-RKT. We demonstrate that Plg treatment of podocytes specifically upregulates NADPH oxidase isoforms NOX2/NOX4 and increases production of mitochondrial-dependent superoxide anion (O2−) that promotes endothelin-1 synthesis. Plg via O2−also promotes expression of the B scavenger receptor CD36 and subsequent increased intracellular cholesterol uptake resulting in podocyte apoptosis. Taken together, our findings suggest that following disruption of the glomerular filtration barrier at the onset of proteinuric disease, podocytes are exposed to Plg resulting in further injury mediated by oxidative stress. We suggest that chronic exposure to Plg could serve as a “second hit” in glomerular disease and that Plg is potentially an attractive target for therapeutic intervention.
Rebuilding the Damaged Heart: Mesenchymal Stem Cells, Cell-Based Therapy, and Engineered Heart Tissue
Authors: Golpanian Samuel , Wolf Ariel , Hatzistergos Konstantinos E. , Hare Joshua M.
Published: June 2016

Mesenchymal stem cells (MSCs) are broadly distributed cells that retain postnatal capacity for self-renewal and multilineage differentiation. MSCs evade immune detection, secrete an array of anti-inflammatory and anti-fibrotic mediators, and very importantly activate resident precursors. These properties form the basis for the strategy of clinical application of cell-based therapeutics for inflammatory and fibrotic conditions. In cardiovascular medicine, administration of autologous or allogeneic MSCs in patients with ischemic and nonischemic cardiomyopathy holds significant promise. Numerous preclinical studies of ischemic and nonischemic cardiomyopathy employing MSC-based therapy have demonstrated that the properties of reducing fibrosis, stimulating angiogenesis, and cardiomyogenesis have led to improvements in the structure and function of remodeled ventricles. Further attempts have been made to augment MSCs' effects through genetic modification and cell preconditioning. Progression of MSC therapy to early clinical trials has supported their role in improving cardiac structure and function, functional capacity, and patient quality of life. Emerging data have supported larger clinical trials that have been either completed or are currently underway. Mechanistically, MSC therapy is thought to benefit the heart by stimulating innate anti-fibrotic and regenerative responses. The mechanisms of action involve paracrine signaling, cell-cell interactions, and fusion with resident cells. Trans-differentiation of MSCs to bona fide cardiomyocytes and coronary vessels is also thought to occur, although at a nonphysiological level. Recently, MSC-based tissue engineering for cardiovascular disease has been examined with quite encouraging results. This review discusses MSCs from their basic biological characteristics to their role as a promising therapeutic strategy for clinical cardiovascular disease.
The Function of V-ATPases in Cancer
Authors: Stransky Laura , Cotter Kristina , Forgac Michael
Published: June 2016

The vacuolar ATPases (V-ATPases) are a family of proton pumps that couple ATP hydrolysis to proton transport into intracellular compartments and across the plasma membrane. They function in a wide array of normal cellular processes, including membrane traffic, protein processing and degradation, and the coupled transport of small molecules, as well as such physiological processes as urinary acidification and bone resorption. The V-ATPases have also been implicated in a number of disease processes, including viral infection, renal disease, and bone resorption defects. This review is focused on the growing evidence for the important role of V-ATPases in cancer. This includes functions in cellular signaling (particularly Wnt, Notch, and mTOR signaling), cancer cell survival in the highly acidic environment of tumors, aiding the development of drug resistance, as well as crucial roles in tumor cell invasion, migration, and metastasis. Of greatest excitement is evidence that at least some tumors express isoforms of V-ATPase subunits whose disruption is not lethal, leading to the possibility of developing anti-cancer therapeutics that selectively target V-ATPases that function in cancer cells.