bluuebunny/crossref_metadata_2025 huggingface dataset:
Objectively Measured Steps/Day in Patients With Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis
Authors: Saunders Travis , Campbell Nerissa , Jason Timothy , Dechman Gail , Hernandez Paul , Thompson Kara , Blanchard Chris M.
Published: June 2016

Background:

Although individual studies have reported on the number of steps/day taken by individuals with chronic obstructive pulmonary disease (COPD), this evidence has not been systematically reviewed or synthesized.

Methods:

MEDLINE and PsycINFO were searched for studies reporting objectively-measured steps/day and percent predicted forced expiratory volume in 1 second (FEV1%) in patients with COPD. Meta-analyses were used to estimate steps/day across studies, while metaregression was used to estimate between-study variance based on clinical and demographic factors (year and location of study, activity monitor brand, number of days wearing the monitor, whether participants were about to enter pulmonary rehabilitation, 6-minute walk distance (6MWD), FEV1%, age, and sex).

Results:

38 studies including 2621 participants met inclusion criteria. The pooled mean estimate was 4579 steps/day (95% CI:4310 to 5208) for individuals with COPD. Only 6MWD, FEV1% and whether patients were about to undergo pulmonary rehabilitation explained a significant portion of the variance (P < 0.1) in univariate meta-regression. In a multivariate model including the above risk factors, only FEV1% was associated with steps/day after adjustment for other covariates.

Conclusions:

These results indicate that patients with COPD achieve extremely low levels of physical activity as assessed by steps/day, and that severity of airflow obstruction is associated with activity level.
Tolerogenic nanoparticles inhibit T cell–mediated autoimmunity through SOCS2
Authors: Yeste Ada , Takenaka Maisa C. , Mascanfroni Ivan D. , Nadeau Meghan , Kenison Jessica E. , Patel Bonny , Tukpah Ann-Marcia , Babon Jenny Aurielle B. , DeNicola Megan , Kent Sally C. , Pozo David , Quintana Francisco J.
Published: June 2016

Nanoparticles decrease disease severity and induce immune tolerance in a mouse model of type 1 diabetes.
The adaptor protein insulin receptor substrate 2 inhibits alternative macrophage activation and allergic lung inflammation
Authors: Dasgupta Preeta , Dorsey Nicolas J. , Li Jiaqi , Qi Xiulan , Smith Elizabeth P. , Yamaji-Kegan Kazuyo , Keegan Achsah D.
Published: June 2016

An adaptor protein mediates feedback inhibition of cytokine receptor signaling to limit airway inflammation.
Science Signaling
Podcast for 21 June 2016: MET and skin cancer
Authors: Yuspa Stuart H. , VanHook Annalisa M.
Published: June 2016

The tyrosine kinase receptor MET promotes squamous cell carcinoma by stimulating signaling through the epidermal growth factor receptor.
Akt regulates primary cilium dynamics
Authors: VanHook Annalisa M.
Published: June 2016

Activated Akt functions at the basal body of primary cilia, a hub for cellular signaling.
Enhancing quality of life as a goal for anticancer therapeutics
Authors: Pettit Syril D. , Lipshultz Steven E. , Cleeland Charles S. , Roberts Samantha , Davis Myrtle , Berridge Brian R. , Kirch Rebecca A.
Published: June 2016

Translational cancer research requires a quality-of-life–driven agenda.
The brainstem and traumatic brain injury
Authors: Lucey Brendan P.
Published: June 2016

Traumatic brain injury damages arousal-producing neurons in the brainstem and hypothalamus.
The splice of life: Understanding human macrophage polarization
Authors: Rayner Katey J.
Published: June 2016

Alternative splicing is highly active in human inflammatory macrophages and may be a causal factor in the genetic risk of developing cardiometabolic disease.
Human Survivors of Disease Outbreaks Caused by Ebola or Marburg Virus Exhibit Cross-Reactive and Long-Lived Antibody Responses
Authors: Natesan Mohan , Jensen Stig M. , Keasey Sarah L. , Kamata Teddy , Kuehne Ana I. , Stonier Spencer W. , Lutwama Julius Julian , Lobel Leslie , Dye John M. , Ulrich Robert G.
Published: June 2016

A detailed understanding of serological immune responses to Ebola and Marburg virus infections will facilitate the development of effective diagnostic methods, therapeutics, and vaccines. We examined antibodies from Ebola or Marburg survivors 1 to 14 years after recovery from disease, by using a microarray that displayed recombinant nucleoprotein (NP), viral protein 40 (VP40), envelope glycoprotein (GP), and inactivated whole virions from six species of filoviruses. All three outbreak cohorts exhibited significant antibody responses to antigens from the original infecting species and a pattern of additional filoviruses that varied by outbreak. NP was the most cross-reactive antigen, while GP was the most specific. Antibodies from survivors of infections by
Marburg marburgvirus
(MARV) species were least cross-reactive, while those from survivors of infections by
Sudan virus
(SUDV) species exhibited the highest cross-reactivity. Based on results revealed by the protein microarray, persistent levels of antibodies to GP, NP, and VP40 were maintained for up to 14 years after infection, and survival of infection caused by one species imparted cross-reactive antibody responses to other filoviruses.
Infection Susceptibility in Gastric Intrinsic Factor (Vitamin B
12
)-Defective Mice Is Subject to Maternal Influences
Authors: Mottram Lynda , Speak Anneliese O. , Selek Reza M. , Cambridge Emma L. , McIntyre Zoe , Kane Leanne , Mukhopadhyay Subhankar , Grove Carolyn , Colin Amy , Brandt Cordelia , Duque-Correa Maria A. , Forbester Jessica , Nguyen Tu Anh Pham , Hale Christine , Vasilliou George S. , Arends Mark J. , Wren Brendan W. , Dougan Gordon , Clare Simon
Published: June 2016

Mice harboring a mutation in the gene encoding gastric intrinsic factor (Gif), a protein essential for the absorption of vitamin B
12
/cobalamin (Cbl), have potential as a model to explore the role of vitamins in infection. The levels of Cbl in the blood of
Gif
tm1a/tm1a
mutant mice were influenced by the maternal genotype, with offspring born to heterozygous (high Cbl, F
1
) mothers exhibiting a significantly higher serum Cbl level than those born to homozygous (low Cbl, F
2
) equivalents. Low Cbl levels correlated with susceptibility to an infectious challenge with
Salmonella enterica
serovar Typhimurium or
Citrobacter rodentium
, and this susceptibility phenotype was moderated by Cbl administration. Transcriptional and metabolic profiling revealed that Cbl deficient mice exhibited a bioenergetic shift similar to a metabolic phenomenon commonly found in cancerous cells under hypoxic conditions known as the Warburg effect, with this metabolic effect being exacerbated further by infection. Our findings demonstrate a role for Cbl in bacterial infection, with potential general relevance to dietary deficiency and infection susceptibility.

IMPORTANCE
Malnutrition continues to be a major public health problem in countries with weak infrastructures. In communities with a high prevalence of poor diet, malnourishment and infectious disease can impact vulnerable individuals such as pregnant women and children. Here, we describe a highly flexible murine model for monitoring maternal and environmental influences of vitamin B
12
metabolism. We also demonstrate the potential importance of vitamin B
12
in controlling susceptibility to bacterial pathogens such as
C. rodentium
and
S
. Typhimurium. We postulate that this model, along with similarly vitamin deficient mice, could be used to further explore the mechanisms associated with micronutrients and susceptibility to diseases, thereby increasing our understanding of disease in the malnourished.
Social determinants of health: poverty, national infrastructure and investment
Authors: Douthit Nathan T , Alemu Haimanot Kasahun
Published: June 2016

This case presentation of a 19-year-old Ethiopian woman diagnosed with nasopharyngeal carcinoma reveals the barriers the patient has to medical treatment, including poverty and a lack of national infrastructure. The patient lives a life of poverty, and the outcome of her illness is a result of her being unable to overcome barriers to accessing health care due to inability to afford transport, lodging and treatment. In this case, the patient's vulnerability to disease due to her poverty is not overcome because of lack of infrastructure. The infrastructure fails to develop because of inadequate investment and other delays in building. The end result is that the patient is vulnerable to disease. Her disease process impacts her family and their contribution to Ethiopia's development.
Patient and family satisfaction levels in the intensive care unit after elective cardiac surgery: study protocol for a randomised controlled trial of a preoperative patient education intervention
Authors: Lai Veronica Ka Wai , Lee Anna , Leung Patricia , Chiu Chun Hung , Ho Ka Man , Gomersall Charles David , Underwood Malcolm John , Joynt Gavin Matthew
Published: June 2016

Introduction

Patients and their families are understandably anxious about the risk of complications and unfamiliar experiences following cardiac surgery. Providing information about postoperative care in the intensive care unit (ICU) to patients and families may lead to lower anxiety levels, and increased satisfaction with healthcare. The objectives of this study are to evaluate the effectiveness of preoperative patient education provided for patients undergoing elective cardiac surgery.

Methods and analysis

100 patients undergoing elective coronary artery bypass graft, with or without valve replacement surgery, will be recruited into a 2-group, parallel, superiority, double-blinded randomised controlled trial. Participants will be randomised to either preoperative patient education comprising of a video and ICU tour with standard care (intervention) or standard education (control). The primary outcome measures are the satisfaction levels of patients and family members with ICU care and decision-making in the ICU. The secondary outcome measures are patient anxiety and depression levels before and after surgery.

Ethics and dissemination

Ethical approval has been obtained from the Joint Chinese University of Hong Kong—New Territories East Cluster Clinical Research Ethics Committee (reference number CREC 2015.308). The findings will be presented at conferences and published in peer-reviewed journals. Study participants will receive a 1-page plain language summary of results.

Trial registration number

ChiCTR-IOR-15006971.
A novel flow cytometric-based method to measure kinase inhibition in sputum from COPD subjects
Authors: Nicholson G C , Holloway R A , Leaker B R , Kilty I , Salganik M , Tan L , Barnes P J , Donnelly L E
Published: June 2016

Introduction

Janus kinases (JAKs) regulate inflammatory gene expression through phosphorylation of signal transducer and activator of transcription (STAT) proteins. Expression of STAT proteins is increased in chronic obstructive pulmonary disease (COPD), and may be involved in driving chronic inflammation. Oral JAK inhibitors are effective as anti-inflammatory therapy but exhibit dose-limiting adverse effects. Development of inhaled compounds would be enhanced by robust biomarkers that directly reflect the anti-inflammatory and pharmacological activity in the lung.

Methods

A novel flow cytometry assay was developed to measure STAT1 phosphorylation in sputum inflammatory cells. The standard sputum processing method was refined to improve sputum cell viability. The flow cytometric assay was used to assess the reproducibility of the measurement of STAT1 phosphorylation and the in vitro activity of a pan JAK-inhibitor on three separate visits in patients with COPD.

Results

Upregulation of STAT1 phosphorylation was measured following in vitro IFNγ stimulation of sputum macrophages (stimulated/unstimulated ratio 1.57; p<0.00001). Upregulation was inhibited following in vitro preincubation with a pan JAK-inhibitor (inhibited+stimulated/unstimulated ratio 0.97). STAT1 phosphorylation activity could only be measured in macrophages.

Conclusions

Sputum from patients with COPD can be used to reproducibly measure phospho-STAT expression in sputum macrophages. The flow cytometry-based method can be used to evaluate kinase inhibitors in vitro and subsequently in ex vivo studies. The assay is particularly useful for the assessment of inhaled compounds where whole blood assays may not be relevant.
Enhancing generational change in patient safety attitudes through peer leadership
Authors: Walpola Ramesh L , Fois Romano A , McLachlan Andrew J , Chen Timothy F
Published: June 2016

Background

Despite peer-led teaching demonstrating benefits in patient safety education, few studies have evaluated these programmes from the perspective of peer leaders.

Objective

To evaluate the impact of peer leader participation in a patient safety education workshop in improving their patient safety attitudes.

Participants

34 final year pharmacy student peer leaders.

Methods

An interactive peer-led patient safety workshop was delivered to 249 first year pharmacy students. Peer leaders' attitudes were assessed 2 months prior to and immediately after peer leader training; and immediately after and 1 month following the workshop. Using a validated patient safety attitudinal survey, repeated measures analysis of variance and pairwise comparisons were used to evaluate changes in four key attitudes over time: being quality improvement focused; internalising errors; questioning more senior healthcare professionals' behaviours; and attitudes towards the open disclosure of errors.

Results

Compared to baseline, peer leaders' attitudes towards open disclosure significantly improved immediately following the workshop (p=0.010) and were sustained after 1 month (p=0.028). Attitudes towards being quality improvement focused also improved significantly 1 month after the workshop (p=0.003).

Conclusions

Participation in a peer-led patient safety education programme benefits both students and peer leaders, enabling further mastery of concepts and enhancing generational change in patient safety practices.
Estimating genetic structure and diversity of cyanobacterial communities in Atlantic forest phyllosphere
Authors: Rigonato Janaina , Gonçalves Natalia , Andreote Ana Paula Dini , Lambais Marcio Rodrigues , Fiore Marli Fátima
Published: June 2016

Cyanobacterial communities on the phyllosphere of 4 plant species inhabiting the endangered Brazilian Atlantic Forest biome were evaluated using cultivation-independent molecular approaches. Total genomic DNA was extracted from cells detached from the surface of leaves of Euterpe edulis, Guapira opposita, Garcinia gardneriana, and Merostachys neesii sampled in 2 Brazilian Atlantic Forest locations along an elevational gradient, i.e., lowland and montane forest. The DNA fingerprinting method PCR–DGGE revealed that the cyanobacterial phyllosphere community structures were mainly influenced by the plant species; geographical location of the plant had little effect. The 16S rRNA gene sequences obtained by clone libraries showed a predominance of nitrogen-fixing cyanobacteria of the order Nostocales, even though the majority of retrieved operational taxonomic units (∼60% of the sequences) showed similarity only to uncultured cyanobacteria phylotypes. The leaf surface of Guapira opposita had the highest richness and diversity of cyanobacteria, whereas the M. neesii (bamboo) had the largest number of copies of cyanobacterial 16S rRNA gene per cm2of leaf. This study investigated cyanobacteria diversity and its distribution pattern in Atlantic forest phyllosphere. The results indicated that plant species is the main driver of cyanobacteria community assemblage in the phyllosphere and that these communities are made up of a high diversity of cyanobacterial taxa that need to be discovered.
Electron two-stream instability and its application in solar and heliophysics
Authors: Che Haihong
Published: June 2016

It is well known that electron beams accelerated in solar flares can drive two-stream instability and produce radio bursts in the solar corona as well as in the interplanetary medium. Recent observations show that the solar wind likely originates from nanoflare-like events near the surface of the Sun where locally heated plasma escapes along open field lines into space. Recent numerical simulations and theoretical studies show that electron two-stream instability (ETSI) driven by nanoflare-accelerated electron beams can produce the observed nanoflare-type radio bursts, the non-Maxwellian electron velocity distribution function of the solar wind, and the kinetic scale turbulence in solar wind. This brief review focus on the basic theoretical framework and recent progress in the nonlinear evolution of ETSI driven by electron beams, including the formation of electron holes, Langmuir wave generation in warm plasma, and the nonlinear modulation instability and Langmuir collapse. Potential applications in heliophysics and astrophysics are discussed.
Relativistic drag and emission radiation pressures in an isotropic photonic gas
Authors: Lee Jeffrey S. , Cleaver Gerald B.
Published: June 2016

By invoking the relativistic spectral radiance, as derived by Lee and Cleaver,1 the drag radiation pressure of a relativistic planar surface moving through an isotropic radiation field, with which it is in thermal equilibrium, is determined in inertial and non-inertial frames. The forward- and backward-directed emission radiation pressures are also derived and compared. A fleeting (inertial frames) or ongoing (some non-inertial frames) Carnot cycle is shown to exist as a result of an intra-surfaces temperature gradient. The drag radiation pressure on an object with an arbitrary frontal geometry is also described.
Designing liquid-crystalline gold nanoparticles via the olefin cross-metathesis reaction
Authors: Nguyen Thanh Tung , Nguyen Thi Le Anh , Deschenaux Robert
Published: June 2016

Liquid-crystalline gold nanoparticles were prepared by grafting mesomorphic [Formula: see text],[Formula: see text]-unsaturated carbonyl olefins onto the organic shell of gold nanoparticles containing terminal olefin ligands by applying the olefin cross-metathesis. The latter reaction was performed under standard conditions using second-generation Grubbs catalyst. The title materials were found to be stable up to 200[Formula: see text] C and gave rise to the formation of smectic A phases in agreement with the structure and nature of the liquid-crystalline promoters. The olefin cross-metathesis proved to be a reaction of choice for the design of liquid-crystalline nanoparticles.
A MARKER-BASED EULERIAN-LAGRANGIAN METHOD FOR MULTIPHASE FLOW WITH SUPERSONIC COMBUSTION APPLICATIONS
Authors: FAN XIAOFENG , WANG JIANGFENG
Published: June 2016

The atomization of liquid fuel is a kind of intricate dynamic process from continuous phase to discrete phase. Procedures of fuel spray in supersonic flow are modeled with an Eulerian-Lagrangian computational fluid dynamics methodology. The method combines two distinct techniques and develops an integrated numerical simulation method to simulate the atomization processes. The traditional finite volume method based on stationary (Eulerian) Cartesian grid is used to resolve the flow field, and multi-component Navier-Stokes equations are adopted in present work, with accounting for the mass exchange and heat transfer occupied by vaporization process. The marker-based moving (Lagrangian) grid is utilized to depict the behavior of atomized liquid sprays injected into a gaseous environment, and discrete droplet model 13 is adopted. To verify the current approach, the proposed method is applied to simulate processes of liquid atomization in supersonic cross flow. Three classic breakup models, TAB model, wave model and K-H/R-T hybrid model, are discussed. The numerical results are compared with multiple perspectives quantitatively, including spray penetration height and droplet size distribution. In addition, the complex flow field structures induced by the presence of liquid spray are illustrated and discussed. It is validated that the maker-based Eulerian-Lagrangian method is effective and reliable.
EFFICIENT CFD/CSD COUPLING METHODS FOR AEROELASTIC APPLICATIONS
Authors: CHEN LONG , XU TIANHAO , XIE JING
Published: June 2016

A fast aeroelastic numerical simulation method using CFD/CSD coupling are developed. Generally, aeroelastic numerical simulation costs much time and significant hardware resources with CFD/CSD coupling. In this paper, dynamic grid method, full implicit scheme, parallel technology and improved coupling method are researched for efficiency simulation. An improved Delaunay graph mapping method is proposed for efficient dynamic grid deform. Hybrid grid finite volume method is used to solve unsteady flow fields. The dual time stepping method based on parallel implicit scheme is used in temporal discretization for efficiency simulation. An approximate system of linear equations is solved by the GMRES algorithm with a LU-SGS preconditioner. This method leads to a significant increase in performance over the explicit and LU-SGS implicit methods. A modification of LU-SGS is proposed to improve the parallel performance. Parallel computing overs a very effective way to improve our productivity in doing CFD/CFD coupling analysis. Improved loose coupling method is an efficiency way over the loose coupling method and tight coupling method. 3D wing's aeroelastic phenomenon is simulated by solving Reynolds-averaged Navier–Stokes equations using improved loose coupling method. The flutter boundary is calculated and agrees well with experimental data. The transonic hole is very clear in numerical simulation results.
GPU IMPLEMENTATION OF A VISCOUS FLOW SOLVER ON UNSTRUCTURED GRIDS
Authors: XU TIANHAO , CHEN LONG
Published: June 2016

Graphics processing units have gained popularities in scientific computing over past several years due to their outstanding parallel computing capability. Computational fluid dynamics applications involve large amounts of calculations, therefore a latest GPU card is preferable of which the peak computing performance and memory bandwidth are much better than a contemporary high-end CPU. We herein focus on the detailed implementation of our GPU targeting Reynolds-averaged Navier-Stokes equations solver based on finite-volume method. The solver employs a vertex-centered scheme on unstructured grids for the sake of being capable of handling complex topologies. Multiple optimizations are carried out to improve the memory accessing performance and kernel utilization. Both steady and unsteady flow simulation cases are carried out using explicit Runge-Kutta scheme. The solver with GPU acceleration in this paper is demonstrated to have competitive advantages over the CPU targeting one.
LARGE-EDDY SIMULATION OF SHOCK-WAVE/TURBULENT BOUNDARY LAYER INTERACTION AND ITS CONTROL USING SPARKJET
Authors: YANG GUANG , YAO YUFENG , FANG JIAN , GAN TIAN , LU LIPENG
Published: June 2016

Large-eddy simulation (LES) of an oblique shock-wave generated by an 8° sharp wedge impinging onto a spatially-developing Mach 2.3 turbulent boundary layer and their interactions has been carried out in this study. The Reynolds number based on the incoming flow property and the boundary layer displacement thickness at the impinging point without shock-wave is 20,000. The detailed numerical approaches are described and the inflow turbulence is generated using the digital filter method to avoid artificial temporal or streamwise periodicity. Numerical results are compared with the available wind tunnel PIV measurements of the same flow conditions. Further LES study on the control of flow separation due to the strong shock-viscous interaction is also conducted by using an active control actuator “SparkJet” concept. The single-pulsed characteristics of the control device are obtained and compared with the experiments. Instantaneous flowfield shows that the “SparkJet” promotes the flow mixing in the boundary layer and enhances its ability to resist the flow separation. The time and spanwise averaged skin friction coefficient distribution demonstrates that the separation bubble length is reduced by maximum 35% with the control exerted.
An assessment of Palaeogene and Neogene clay deposits in Denmark as possible host rocks for final disposal of low- and intermediate-level radioactive waste
Authors: Gravesen Peter , Pedersen Stig A. Schack , Nilsson Bertel , Binderup Merete
Published: June 2016

In Denmark, mapping and preliminary investigations of Palaeogene and Early Neogene clay deposits have been performed over the past 5 years. The goal was to locate potential host rocks for the final disposal of low- and intermediate-level radioactive waste from the Danish Research Centre Risø, which has to be decommissioned within the next 5–8 years. Five areas with low-permeability Paleocene and Oligocene clay formations, situated in northern Jylland, NE Fyn and southern Lolland, not far from the Baltic coast at Femern Belt, have been suggested. The clay formations are between 75 and 150 m thick, and have large lateral distribution. They are covered by thin layers of glacial clayey tills and the shallow depth to the clay formations is attractive, partly because they are easy to access and partly because there are no groundwater aquifers situated above or below the clay deposits. The paper gives an overall review of the characteristics of the six different clay formations within four of the areas.
Combining high-resolution two-phase with simplified single-phase simulations in order to optimize the performance of PA/SA simulations for a deep geological repository for radioactive waste
Authors: Schaedle Philipp , Kaempfer Thomas , Pépin Guillaume , Wendling Jacques , Brommundt Juergen
Published: June 2016

The transport of a radioactive solute during the transient thermo-hydraulic regime with gas generation in and around a disposal cell depends on complex multi-phase processes. Numerical simulations can improve the understanding of the system by providing detailed information on the temporal and spatial distribution of the radionuclides. In particular, their fluxes can be computed under the given transient conditions considering radionuclide, heat and gas release from the waste. However, such detailed multi-phase simulations are very demanding with respect to computational resources and time. Based on the knowledge gained from such complex simulations, we have developed a robust simplified single-phase approach for performance and safety assessment, the improved efficiency of which enables extensive parameter studies. The simplified approach comprises, on the one hand, homogenization of features of high detail and, on the other hand, the employment of two-phase simulation results that are used to deduce equivalent single-phase parameterizations. The results have been validated with various benchmark criteria at well-defined interfaces in the modelled disposal cells based on the simulated radionuclides fluxes.
Towards efficient traffic-analysis resistant anonymity networks
Authors: Le Blond Stevens , Choffnes David , Zhou Wenxuan , Druschel Peter , Ballani Hitesh , Francis Paul
Published: June 2016

Existing IP anonymity systems tend to sacrifice one of low latency, high bandwidth, or resistance to traffic-analysis. High-latency mix-nets like Mixminion batch messages to resist traffic-analysis at the expense of low latency. Onion routing schemes like Tor deliver low latency and high bandwidth, but are not designed to withstand traffic analysis. Designs based on DC-nets or broadcast channels resist traffic analysis and provide low latency, but are limited to low bandwidth communication.

In this paper, we present the design, implementation, and evaluation of Aqua, a high-bandwidth anonymity system that resists traffic analysis. We focus on providing strong anonymity for BitTorrent, and evaluate the performance of Aqua using traces from hundreds of thousands of actual BitTorrent users. We show that Aqua achieves latency low enough for efficient bulk TCP flows, bandwidth sufficient to carry BitTorrent traffic with reasonable efficiency, and resistance to traffic analysis within anonymity sets of hundreds of clients. We conclude that Aqua represents an interesting new point in the space of anonymity network designs.
zUpdate
Authors: Liu Hongqiang Harry , Wu Xin , Zhang Ming , Yuan Lihua , Wattenhofer Roger , Maltz David
Published: June 2016

Datacenter networks (DCNs) are constantly evolving due to various updates such as switch upgrades and VM migrations. Each update must be carefully planned and executed in order to avoid disrupting many of the mission-critical, interactive applications hosted in DCNs. The key challenge arises from the inherent difficulty in synchronizing the changes to many devices, which may result in unforeseen transient link load spikes or even congestions. We present one primitive, zUpdate, to perform congestion-free network updates under asynchronous switch and traffic matrix changes. We formulate the update problem using a network model and apply our model to a variety of representative update scenarios in DCNs. We develop novel techniques to handle several practical challenges in realizing zUpdate as well as implement the zUpdate prototype on OpenFlow switches and deploy it on a testbed that resembles real DCN topology. Our results, from both real-world experiments and large-scale trace-driven simulations, show that zUpdate can effectively perform congestion-free updates in production DCNs.
Mosaic
Authors: Xia Ning , Song Han Hee , Liao Yong , Iliofotou Marios , Nucci Antonio , Zhang Zhi-Li , Kuzmanovic Aleksandar
Published: June 2016

With the proliferation of online social networking (OSN) and mobile devices, preserving user privacy has become a great challenge. While prior studies have directly focused on OSN services, we call attention to the privacy leakage in
mobile network data
. This concern is motivated by two factors. First, the prevalence of OSN usage leaves identifiable digital footprints that can be traced back to users in the real-world. Second, the association between users and their mobile devices makes it easier to associate traffic to its owners. These pose a serious threat to user privacy as they enable an adversary to attribute significant portions of data traffic including the ones with
NO
identity leaks to network users' true identities. To demonstrate its feasibility, we develop the
Tessellation
methodology. By applying Tessellation on traffic from a cellular service provider (CSP), we show that up to 50% of the traffic can be attributed to the names of users. In addition to revealing the user identity, the reconstructed profile, dubbed as "mosaic," associates personal information such as political views, browsing habits, and favorite apps to the users. We conclude by discussing approaches for preventing and mitigating the alarming leakage of sensitive user information.
SplitX
Authors: Chen Ruichuan , Akkus Istemi Ekin , Francis Paul
Published: June 2016

There is a growing body of research on mechanisms for preserving online user privacy while still allowing aggregate queries over private user data. A common approach is to store user data at users' devices, and to query the data in such a way that a differentially private noisy result is produced without exposing individual user data to any system component. A particular challenge is to design a system that scales well while limiting how much the malicious users can distort the result. This paper presents
SplitX
, a high-performance analytics system for making differentially private queries over distributed user data. SplitX is typically two to three orders of magnitude more efficient in bandwidth, and from three to five orders of magnitude more efficient in computation than previous comparable systems, while operating under a similar trust model. SplitX accomplishes this performance by replacing public-key operations with exclusive-or operations. This paper presents the design of SplitX, analyzes its security and performance, and describes its implementation and deployment across 416 users.
Reducing web latency
Authors: Flach Tobias , Dukkipati Nandita , Terzis Andreas , Raghavan Barath , Cardwell Neal , Cheng Yuchung , Jain Ankur , Hao Shuai , Katz-Bassett Ethan , Govindan Ramesh
Published: June 2016

To serve users quickly, Web service providers build infrastructure closer to clients and use multi-stage transport connections. Although these changes reduce client-perceived round-trip times, TCP's current mechanisms fundamentally limit latency improvements. We performed a measurement study of a large Web service provider and found that, while connections with no loss complete close to the ideal latency of one round-trip time, TCP's timeout-driven recovery causes transfers with loss to take five times longer on average.

In this paper, we present the design of novel loss recovery mechanisms for TCP that judiciously use redundant transmissions to minimize timeout-driven recovery.
Proactive, Reactive,
and
Corrective
are three qualitatively-different, easily-deployable mechanisms that (1) proactively recover from losses, (2) recover from them as quickly as possible, and (3) reconstruct packets to mask loss. Crucially, the mechanisms are compatible both with middleboxes and with TCP's existing congestion control and loss recovery. Our large-scale experiments on Google's production network that serves billions of flows demonstrate a 23% decrease in the mean and 47% in 99th percentile latency over today's TCP.
Ambient backscatter
Authors: Liu Vincent , Parks Aaron , Talla Vamsi , Gollakota Shyamnath , Wetherall David , Smith Joshua R.
Published: June 2016

We present the design of a communication system that enables two devices to communicate using ambient RF as the only source of power. Our approach leverages existing TV and cellular transmissions to eliminate the need for wires and batteries, thus enabling ubiquitous communication where devices can communicate among themselves at unprecedented scales and in locations that were previously inaccessible.

To achieve this, we introduce ambient backscatter, a new communication primitive where devices communicate by backscattering ambient RF signals. Our design avoids the expensive process of generating radio waves; backscatter communication is orders of magnitude more power-efficient than traditional radio communication. Further, since it leverages the ambient RF signals that are already around us, it does not require a dedicated power infrastructure as in traditional backscatter communication. To show the feasibility of our design, we prototype ambient backscatter devices in hardware and achieve information rates of 1 kbps over distances of 2.5 feet and 1.5 feet, while operating outdoors and indoors respectively. We use our hardware prototype to implement proof-of-concepts for two previously infeasible ubiquitous communication applications.
BigStation
Authors: Yang Qing , Li Xiaoxiao , Yao Hongyi , Fang Ji , Tan Kun , Hu Wenjun , Zhang Jiansong , Zhang Yongguang
Published: June 2016

Multi-user multiple-input multiple-output (MU-MIMO) is the latest communication technology that promises to linearly increase the wireless capacity by deploying more antennas on access points (APs). However, the large number of MIMO antennas will generate a huge amount of digital signal samples in real time. This imposes a grand challenge on the AP design by multiplying the computation and the I/O requirements to process the digital samples. This paper presents BigStation, a scalable architecture that enables realtime signal processing in large-scale MIMO systems which may have tens or hundreds of antennas. Our strategy to scale is to extensively parallelize the MU-MIMO processing on many simple and low-cost commodity computing devices. Our design can incrementally support more antennas by proportionally adding more computing devices. To reduce the overall processing latency, which is a critical constraint for wireless communication, we parallelize the MU-MIMO processing with a distributed pipeline based on its computation and communication patterns. At each stage of the pipeline, we further use data partitioning and computation partitioning to increase the processing speed. As a proof of concept, we have built a BigStation prototype based on commodity PC servers and standard Ethernet switches. Our prototype employs 15 PC servers and can support real-time processing of 12 software radio antennas. Our results show that the BigStation architecture is able to scale to tens to hundreds of antennas. With 12 antennas, our BigStation prototype can increase wireless capacity by 6.8x with a low mean processing delay of 860μs. While this latency is not yet low enough for the 802.11 MAC, it already satisfies the real-time requirements of many existing wireless standards, e.g., LTE and WCDMA.
Leveraging endpoint flexibility in data-intensive clusters
Authors: Chowdhury Mosharaf , Kandula Srikanth , Stoica Ion
Published: June 2016

Many applications do not constrain the destinations of their network transfers. New opportunities emerge when such transfers contribute a large amount of network bytes. By choosing the endpoints to avoid congested links, completion times of these transfers as well as that of others without similar flexibility can be improved. In this paper, we focus on leveraging the flexibility in replica placement during writes to cluster file systems (CFSes), which account for
almost half
of all cross-rack traffic in data-intensive clusters. The replicas of a CFS write can be placed in any subset of machines as long as they are in multiple fault domains and ensure a balanced use of storage throughout the cluster.

We study CFS interactions with the cluster network, analyze optimizations for replica placement, and propose Sinbad -- a system that identifies imbalance and adapts replica destinations to navigate around congested links. Experiments on EC2 and trace-driven simulations show that block writes complete 1.3X (respectively, 1.58X) faster as the network becomes more balanced. As a collateral benefit, end-to-end completion times of data-intensive jobs improve as well. Sinbad does so with little impact on the long-term storage balance.
SIMPLE-fying middlebox policy enforcement using SDN
Authors: Qazi Zafar Ayyub , Tu Cheng-Chun , Chiang Luis , Miao Rui , Sekar Vyas , Yu Minlan
Published: June 2016

Networks today rely on middleboxes to provide critical performance, security, and policy compliance capabilities. Achieving these benefits and ensuring that the traffic is directed through the desired sequence of middleboxes requires significant manual effort and operator expertise. In this respect, Software-Defined Networking (SDN) offers a promising alternative. Middleboxes, however, introduce new aspects (e.g., policy composition, resource management, packet modifications) that fall outside the purvey of traditional L2/L3 functions that SDN supports (e.g., access control or routing).

This paper presents SIMPLE, a SDN-based policy enforcement layer for efficient middlebox-specific "traffic steering''. In designing SIMPLE, we take an explicit stance to work within the constraints of legacy middleboxes and existing SDN interfaces. To this end, we address algorithmic and system design challenges to demonstrate the feasibility of using SDN to simplify middlebox traffic steering. In doing so, we also take a significant step toward addressing industry concerns surrounding the ability of SDN to integrate with existing infrastructure and support L4-L7 capabilities.
Less pain, most of the gain
Authors: Fayazbakhsh Seyed Kaveh , Lin Yin , Tootoonchian Amin , Ghodsi Ali , Koponen Teemu , Maggs Bruce , Ng K.C. , Sekar Vyas , Shenker Scott
Published: June 2016

Information-Centric Networking (ICN) has seen a significant resurgence in recent years. ICN promises benefits to users and service providers along several dimensions (e.g., performance, security, and mobility). These benefits, however, come at a non-trivial cost as many ICN proposals envision adding significant complexity to the network by having routers serve as content caches and support nearest-replica routing. This paper is driven by the simple question of whether this additional complexity is justified and if we can achieve these benefits in an incrementally deployable fashion. To this end, we use trace-driven simulations to analyze the quantitative benefits attributed to ICN (e.g., lower latency and congestion). Somewhat surprisingly, we find that pervasive caching and nearest-replica routing are not fundamentally necessary---most of the performance benefits can be achieved with simpler caching architectures. We also discuss how the qualitative benefits of ICN (e.g., security, mobility) can be achieved without any changes to the network. Building on these insights, we present a proof-of-concept design of an incrementally deployable ICN architecture.
Developing a predictive model of quality of experience for internet video
Authors: Balachandran Athula , Sekar Vyas , Akella Aditya , Seshan Srinivasan , Stoica Ion , Zhang Hui
Published: June 2016

Improving users' quality of experience (QoE) is crucial for sustaining the advertisement and subscription based revenue models that enable the growth of Internet video. Despite the rich literature on video and QoE measurement, our understanding of Internet video QoE is limited because of the shift from traditional methods of measuring video quality (e.g., Peak Signal-to-Noise Ratio) and user experience (e.g., opinion scores). These have been replaced by new quality metrics (e.g., rate of buffering, bitrate) and new engagement centric measures of user experience (e.g., viewing time and number of visits). The goal of this paper is to develop a predictive model of Internet video QoE. To this end, we identify two key requirements for the QoE model: (1) it has to be tied in to observable user engagement and (2) it should be actionable to guide practical system design decisions. Achieving this goal is challenging because the quality metrics are interdependent, they have complex and counter-intuitive relationships to engagement measures, and there are many external factors that confound the relationship between quality and engagement (e.g., type of video, user connectivity). To address these challenges, we present a data-driven approach to model the metric interdependencies and their complex relationships to engagement, and propose a systematic framework to identify and account for the confounding factors. We show that a delivery infrastructure that uses our proposed model to choose CDN and bitrates can achieve more than 20\% improvement in overall user engagement compared to strawman approaches.
Ananta
Authors: Patel Parveen , Bansal Deepak , Yuan Lihua , Murthy Ashwin , Greenberg Albert , Maltz David A. , Kern Randy , Kumar Hemant , Zikos Marios , Wu Hongyu , Kim Changhoon , Karri Naveen
Published: June 2016

Layer-4 load balancing is fundamental to creating scale-out web services. We designed and implemented Ananta, a scale-out layer-4 load balancer that runs on commodity hardware and meets the performance, reliability and operational requirements of multi-tenant cloud computing environments. Ananta combines existing techniques in routing and distributed systems in a unique way and splits the components of a load balancer into a consensus-based reliable control plane and a decentralized scale-out data plane. A key component of Ananta is an agent in every host that can take over the packet modification function from the load balancer, thereby enabling the load balancer to naturally scale with the size of the data center. Due to its distributed architecture, Ananta provides direct server return (DSR) and network address translation (NAT) capabilities across layer-2 boundaries. Multiple instances of Ananta have been deployed in the Windows Azure public cloud with combined bandwidth capacity exceeding 1Tbps. It is serving traffic needs of a diverse set of tenants, including the blob, table and relational storage services. With its scale-out data plane we can easily achieve more than 100Gbps throughput for a single public IP address. In this paper, we describe the requirements of a cloud-scale load balancer, the design of Ananta and lessons learnt from its implementation and operation in the Windows Azure public cloud.
Speeding up distributed request-response workflows
Authors: Jalaparti Virajith , Bodik Peter , Kandula Srikanth , Menache Ishai , Rybalkin Mikhail , Yan Chenyu
Published: June 2016

We found that interactive services at Bing have highly variable datacenter-side processing latencies because their processing consists of many sequential stages, parallelization across 10s-1000s of servers and aggregation of responses across the network. To improve the tail latency of such services, we use a few building blocks: reissuing laggards elsewhere in the cluster, new policies to return incomplete results and speeding up laggards by giving them more resources. Combining these building blocks to reduce the overall latency is non-trivial because for the same amount of resource (e.g., number of reissues), different stages improve their latency by different amounts. We present Kwiken, a framework that takes an end-to-end view of latency improvements and costs. It decomposes the problem of minimizing latency over a general processing DAG into a manageable optimization over individual stages. Through simulations with production traces, we show sizable gains; the 99th percentile of latency improves by over 50% when just 0.1% of the responses are allowed to have partial results and by over 40% for 25% of the services when just 5% extra resources are used for reissues.
Dude, where's my card?
Authors: Wang Jue , Katabi Dina
Published: June 2016

RFIDs are emerging as a vital component of the Internet of Things. In 2012, billions of RFIDs have been deployed to locate equipment, track drugs, tag retail goods, etc. Current RFID systems, however, can only identify whether a tagged object is within radio range (which could be up to tens of meters), but cannot pinpoint its exact location. Past proposals for addressing this limitation rely on a line-of-sight model and hence perform poorly when faced with multipath effects or non-line-of-sight, which are typical in real-world deployments. This paper introduces the first fine-grained RFID positioning system that is robust to multipath and non-line-of-sight scenarios. Unlike past work, which considers multipath as detrimental, our design exploits multipath to accurately locate RFIDs. The intuition underlying our design is that nearby RFIDs experience a similar multipath environment (e.g., reflectors in the environment) and thus exhibit similar
multipath profiles
. We capture and extract these multipath profiles by using a synthetic aperture radar (SAR) created via antenna motion. We then adapt dynamic time warping (DTW) techniques to pinpoint a tag's location. We built a prototype of our design using USRP software radios. Results from a deployment of 200 commercial RFIDs in our university library demonstrate that the new design can locate misplaced books with a median accuracy of 11~cm.
pFabric
Authors: Alizadeh Mohammad , Yang Shuang , Sharif Milad , Katti Sachin , McKeown Nick , Prabhakar Balaji , Shenker Scott
Published: June 2016

In this paper we present pFabric, a minimalistic datacenter transport design that provides near theoretically optimal flow completion times even at the 99th percentile for short flows, while still minimizing average flow completion time for long flows. Moreover, pFabric delivers this performance with a very simple design that is based on a key conceptual insight: datacenter transport should decouple flow scheduling from rate control. For flow scheduling, packets carry a single priority number set independently by each flow; switches have very small buffers and implement a very simple priority-based scheduling/dropping mechanism. Rate control is also correspondingly simpler; flows start at line rate and throttle back only under high and persistent packet loss. We provide theoretical intuition and show via extensive simulations that the combination of these two simple mechanisms is sufficient to provide near-optimal performance.