TCP smart framing: a segmentation algorithm to reduce TCP latency

TCP Smart Framing, or TCP-SF for short, enables the Fast Retransmit/Recovery algorithms even when the congestion window is small. Without modifying the TCP congestion control based on the additive-increase/multiplicative-decrease paradigm, TCP-SF adopts a novel segmentation algorithm: while Classic TCP always tries to send full-sized segments, a TCP-SF source adopts a more flexible segmentation algorithm to try and always have a number of in-flight segments larger than 3 so as to enable Fast Recovery. We motivate this choice by real traffic measurements, which indicate that today's traffic is populated by short-lived flows, whose only means to recover from a packet loss is by triggering a Retransmission Timeout. The key idea of TCP-SF can be implemented on top of any TCP flavor, from Tahoe to SACK, and requires modifications to the server TCP stack only, and can be easily coupled with recent TCP enhancements. The performance of the proposed TCP modification were studied by means of simulations, live measurements and an analytical model. In addition, the analytical model we have devised has a general scope, making it a valid tool for TCP performance evaluation in the small window region. Improvements are remarkable under several buffer management schemes, and maximized by byte-oriented schemes

A Hybrid Adaptive Protocol for Reliable Data Delivery in WSNs with Multiple Mobile Sinks

In this paper we deal with reliable and energy-efficient data delivery in sparse Wireless Sensor Networks with multiple Mobile Sinks (MSs). This is a critical task, especially when MSs move randomly, as interactions with sensor nodes are unpredictable, typically of short duration, and affected by message losses. In this paper we propose an adaptive data delivery protocol that combines efficiently erasure coding with an ARQ scheme. The key features of the proposed protocol are: (i) the use of redundancy to cope efficiently with message losses, and (ii) the ability of adapting the level of redundancy based on feedbacks sent back by MSs through ACKs. We observed by simulation that our protocol outperforms an alternative protocol that relies only on an ARQ scheme, even when there is a single MS. We also validated our simulation results through a set of experimental measurements based on real sensor nodes. Our results show that the adoption of encoding techniques is beneficial to energy-efficient (and reliable) data delivery in WSNs with Mobile Sinks

Scientific Opinion on the pest categorisation of Citrus tristeza virus

The Panel on Plant Health performed a pest categorisation of European isolates of Citrus tristeza virus (CTV) for the European Union (EU) territory. European CTV isolates are listed in Annexes IIAII and IIB of Directive 2000/29/EC. CTV is a well-defined and easily diagnosed Closterovirus species transmitted by the vegetative multiplication of infected hosts and through the activity of aphid vectors. Toxoptera citricida is the most efficient vector but Aphis gossypii is the most important in Europe. European isolates of CTV have been reported in seven of the eight EU Member States (MSs) with significant citrus production. The natural host range of CTV is restricted to citrus species and to a few, related genera, such as Fortunella and Poncirus. CTV is unlikely to be affected by ecoclimatic conditions in regions where its host plants are grown and has the potential to establish in southern regions of the EU territory. The majority of European CTV isolates cause severe decline symptoms (tristeza disease) in several citrus species, in particular sweet orange and mandarin grafted on susceptible sour orange or lemon rootstocks, which are commonly used in many EU MSs with the exception of Spain and, to a lesser extent, France. Symptoms of the severe stem pitting disease (SP) have not been reported by any EU MSs, despite the identification of isolates closely related to non-European isolates that cause SP in other regions of the world. The observed impact of CTV is on citrus industries still heavily reliant on susceptible rootstocks. Replacing those with CTV-tolerant rootstocks, as was done in Spain, virtually eliminates the impact of CTV in the absence of SP. Comprehensive certification systems can also reduce CTV spread and impact. The most critical area of uncertainty concerns the potential ability of some European isolates to cause SP in sweet orange

QualDash: Adaptable Generation of Visualisation Dashboards for Healthcare Quality Improvement

YesAdapting dashboard design to different contexts of use is an open question in visualisation research. Dashboard designers often seek to strike a balance between dashboard adaptability and ease-of-use, and in hospitals challenges arise from the vast diversity of key metrics, data models and users involved at different organizational levels. In this design study, we present QualDash, a dashboard generation engine that allows for the dynamic configuration and deployment of visualisation dashboards for healthcare quality improvement (QI). We present a rigorous task analysis based on interviews with healthcare professionals, a co-design workshop and a series of one-on-one meetings with front line analysts. From these activities we define a metric card metaphor as a unit of visual analysis in healthcare QI, using this concept as a building block for generating highly adaptable dashboards, and leading to the design of a Metric Specification Structure (MSS). Each MSS is a JSON structure which enables dashboard authors to concisely configure unit-specific variants of a metric card, while offloading common patterns that are shared across cards to be preset by the engine. We reflect on deploying and iterating the design of QualDash in cardiology wards and pediatric intensive care units of five NHS hospitals. Finally, we report evaluation results that demonstrate the adaptability, ease-of-use and usefulness of QualDash in a real-world scenario

A gp41 MPER-specific llama VHH requires a hydrophobic CDR3 for neutralization but not for antigen recognition

The membrane proximal external region (MPER) of the HIV-1 glycoprotein gp41 is targeted by the broadly neutralizing antibodies 2F5 and 4E10. To date, no immunization regimen in animals or humans has produced HIV-1 neutralizing MPER-specific antibodies. We immunized llamas with gp41-MPER proteoliposomes and selected a MPER-specific single chain antibody (VHH), 2H10, whose epitope overlaps with that of mAb 2F5. Bi-2H10, a bivalent form of 2H10, which displayed an approximately 20-fold increased affinity compared to the monovalent 2H10, neutralized various sensitive and resistant HIV-1 strains, as well as SHIV strains in TZM-bl cells. X-ray and NMR analyses combined with mutagenesis and modeling revealed that 2H10 recognizes its gp41 epitope in a helical conformation. Notably, tryptophan 100 at the tip of the long CDR3 is not required for gp41 interaction but essential for neutralization. Thus bi-2H10 is an anti-MPER antibody generated by immunization that requires hydrophobic CDR3 determinants in addition to epitope recognition for neutralization similar to the mode of neutralization employed by mAbs 2F5 and 4E10

Energy-Efficient Power Control in Cell-Free and User-Centric Massive MIMO at Millimeter Wave

In a cell-free massive MIMO architecture a very large number of distributed access points simultaneously and jointly serves a much smaller number of mobile stations; a variant of the cell-free technique is the user-centric approach, wherein each access point just serves a reduced set of mobile stations. This paper introduces and analyzes the cell-free and user-centric architectures at millimeter wave frequencies, considering a training-based channel estimation phase, and the downlink and uplink data transmission phases. First of all, a multiuser clustered millimeter wave channel model is introduced in order to account for the correlation among the channels of nearby users; second, an uplink multiuser channel estimation scheme is described along with low-complexity hybrid analog/digital beamforming architectures. Third, the non-convex problem of power allocation for downlink global energy efficiency maximization is addressed. Interestingly, in the proposed schemes no channel estimation is needed at the mobile stations, and the beamforming schemes used at the mobile stations are channel-independent and have a very simple structure. Numerical results show the benefits granted by the power control procedure, that the considered architectures are effective, and permit assessing the loss incurred by the use of the hybrid beamformers and by the channel estimation errors.Comment: To appear on the IEEE Transactions on Green Communications and Networking; originally submitted on April 24, 2018 and finally accepted for publication on March 24, 201