RTT-Based Congestion Control for the Internet of Things

Part 1: IoT and Sensor NetworksInternational audienceThe design of scalable and reliable transport protocols for IoT environments is still an unsolved issue. A simple stop-and-wait congestion control method and a lightweight reliability mechanism are only implemented in CoAP, an application protocol that provides standardised RESTful services for IoT devices. Inspired by delay-based congestion control algorithms that have been proposed for the TCP, in this work we propose a rate control technique that leverages measurements of round-trip times (RTTs) to infer network state and to determine the flow rate that would prevent network congestion. Our key idea is that the growth of RTT variance, coupled with thresholds on CoAP message losses, is an effective way to detect the onset of network congestion. To validate our approach, we conduct a comparative performance analysis with the two loss-based congestion control methods of standard CoAP under different application scenarios. Results show that our solution outperforms the alternative methods, with a significant improvement of fairness and robustness against unacknowledged traffic

WiTNNess: An international natural history study of infantile‐onset TNNT1 myopathy

ABSTRACT Objective We created WiTNNess as a hybrid prospective/cross‐sectional observational study to simulate a clinical trial for infantile‐onset TNNT1 myopathy. Our aims were to identify populations for future trial enrollment, rehearse outcome assessments, specify endpoints, and refine trial logistics. Methods Eligible participants had biallelic pathogenic variants of TNNT1 and infantile‐onset proximal weakness without confounding conditions. The primary endpoint was ventilator‐free survival. “Thriving” was a secondary endpoint defined as the ability to swallow and grow normally without non‐oral feeding support. Endpoints of gross motor function included independent sitting and standing as defined by the Word Health Organization, a novel TNNT1 abbreviated motor score, and video mapping of limb movement. We recorded adverse events, concomitant medications, and indices of organ function to serve as comparators of safety in future trials. Results Sixteen children were enrolled in the aggregate cohort (6 prospective, 10 cross‐sectional; median census age 2.3 years, range 0.5–13.8). Median ventilator‐free survival was 20.2 months and probability of death or permanent mechanical ventilation was 100% by age 60 months. All six children (100%) in the prospective arm failed to thrive by age 12 months. Only 2 of 16 (13%) children in the aggregate cohort sat independently and none stood alone. Novel exploratory motor assessments also proved informative. Laboratory and imaging data suggest that primary manifestations of TNNT1 deficiency are restricted to skeletal muscle. Interpretation WiTNNess allowed us to streamline and economize the collection of historical control data without compromising scientific rigor, and thereby establish a sound operational framework for future clinical trials

Presenting and visualizing image results for professional image searchers: A field evaluation

Creative professionals such as journalists and copywriters are an important group of users who need to search for images as part of their work task. We describe the design and evaluation of a 'high density' image search interface targeted at this user group. We use a field evaluation together with a qualitative approach with creative professionals to gather feedback on the high density in-terface design. Our results show that creative professional viewed the interface favourably be-cause they were able to get a quick overview of research results. We make suggestions for the ap-propriateness of high density interfaces for different work contexts, and further work in terms of layouts of images in high density interfaces

The synergistic effect of time of exposure, distance and no use of personal protective equipment in the determination of SARS-CoV-2 infection: Results of a contact tracing follow-up study in healthcareworkers

The aim of this study is to assess the effect of contact time, contact distance and the use of personal protective equipment on the determination of SARS-CoV-2 infection in healthcare workers (HCWs). This study consists of an analysis of data gathered for safety reasons at the Sapienza Teaching Hospital Policlinico Umberto I in Rome through the surveillance system that was put into place after the worsening of the COVID-19 pandemic. The studied subjects consist of HCWs who were put under health surveillance, i.e., all employees who were in contact with subjects who were confirmed to have tested positive for SARS-CoV-2. The HCWs under surveillance were monitored for a period encompassing ten days after the date of contact, during which they undertook nasopharyngeal swab tests analysed through RT-PCR (RealStar®SARS-CoV-2 Altona Diagnostic-Germany). Descriptive and univariate analyses have been undertaken, considering the following as risk factors: (a) no personal protective equipment use (PPE); (b) Distance < 1 m between the positive and contact persons; (c) contact time > 150. Finally, a Cox regression and an analysis of the level of synergism between factors, as specified by Rothman, were carried out. We analysed data from 1273 HCWs. Of these HCWs, 799 (62.8%) were females, with a sample average age of 47.8 years. Thirty-nine (3.1%) tested positive during surveillance. The overall incidence rate was 0.4 per 100 person-days. Time elapsed from the last exposure and a positive RT-PCR result ranged from 2 to 17 days (mean = 7, median = 6 days). In the univariate analysis, a distance <1 m and a contact time > 150 proved to be risk factors for the SARS-CoV-2 infection, with a hazard ratio (HR) of 2.62 (95% CI: 1.11-6.19) and 3.59 (95% IC: 1.57-8.21), respectively. The synergism analysis found the highest synergism between the “no PPE use” x “Contact time”. The synergy index S remains strongly positive also in the analysis of the factors “no PPE use” x “Distance” and “Time of contact” x “Distance”. This study confirms the absolute need to implement safety protocols during the pandemic and to use the correct PPE within health facilities in order to prevent SARS-CoV-2 infection. The analysis shows that among the factors considered (contact time and distance, no use of PPE), there is a strong synergistic effect

Presenting and visualizing results on an image retrieval user interface

The volume of images available online has increased significantly but the choices offered by image retrieval systems have not kept pace. We describe the design and evaluation of a ‘high density’ image search interface focusing on the results pages. We quantitatively and qualitatively compared image presentation on a high density interface with a traditional image search interface. Our results show that users had major problems with high-density interfaces for images due to information overload. We point to further work which could improve the user experience