A PIV and CFD analysis of natural convection ice melting

The melting of a vertical ice cylinder in water is investigated in this paper. The experiments were carried out in a water-filled cylindrical Perspex barrel with adiabatic walls for Rayleigh numbers of 0.22x108 and 0.475x108. The ice crystal is suspended in the water and experimental images of the natural convection melting process were obtained using both shadowgraphy and particle image velocimetry (PIV) techniques. This data is compared with a numerical model which attempts to capture the melt-front on a fixed computational grid. The numerical model takes into account the density inversion effects in the water. The results show the applicability of PIV to this type of flow and demonstrate a simple numerical model to effectively resolve the melting phenomenon

BitTorrent Sync: Network Investigation Methodology

The volume of personal information and data most Internet users find themselves amassing is ever increasing and the fast pace of the modern world results in most requiring instant access to their files. Millions of these users turn to cloud based file synchronisation services, such as Dropbox, Microsoft Skydrive, Apple iCloud and Google Drive, to enable "always-on" access to their most up-to-date data from any computer or mobile device with an Internet connection. The prevalence of recent articles covering various invasion of privacy issues and data protection breaches in the media has caused many to review their online security practices with their personal information. To provide an alternative to cloud based file backup and synchronisation, BitTorrent Inc. released an alternative cloudless file backup and synchronisation service, named BitTorrent Sync to alpha testers in April 2013. BitTorrent Sync's popularity rose dramatically throughout 2013, reaching over two million active users by the end of the year. This paper outlines a number of scenarios where the network investigation of the service may prove invaluable as part of a digital forensic investigation. An investigation methodology is proposed outlining the required steps involved in retrieving digital evidence from the network and the results from a proof of concept investigation are presented.Comment: 9th International Conference on Availability, Reliability and Security (ARES 2014

Boosted Higgs →bbˉ\rightarrow b\bar{b} in vector-boson associated production at 14 TeV

The production of the Standard Model Higgs boson in association with a vector boson, followed by the dominant decay to $H \rightarrow b\bar{b}$, is a strong prospect for confirming and measuring the coupling to $b$-quarks in $pp$ collisions at $\sqrt{s}=14$ TeV. We present an updated study of the prospects for this analysis, focussing on the most sensitive highly Lorentz-boosted region. The evolution of the efficiency and composition of the signal and main background processes as a function of the transverse momentum of the vector boson are studied covering the region $200-1000$ GeV, comparing both a conventional dijet and jet substructure selection. The lower transverse momentum region ($200-400$ GeV) is identified as the most sensitive region for the Standard Model search, with higher transverse momentum regions not improving the statistical sensitivity. For much of the studied region ($200-600$ GeV), a conventional dijet selection performs as well as the substructure approach, while for the highest transverse momentum regions ($> 600$ GeV), which are particularly interesting for Beyond the Standard Model and high luminosity measurements, the jet substructure techniques are essential.Comment: 13 pages.(Fixed figure layout error

BitTorrent Sync: First Impressions and Digital Forensic Implications

With professional and home Internet users becoming increasingly concerned with data protection and privacy, the privacy afforded by popular cloud file synchronisation services, such as Dropbox, OneDrive and Google Drive, is coming under scrutiny in the press. A number of these services have recently been reported as sharing information with governmental security agencies without warrants. BitTorrent Sync is seen as an alternative by many and has gathered over two million users by December 2013 (doubling since the previous month). The service is completely decentralised, offers much of the same synchronisation functionality of cloud powered services and utilises encryption for data transmission (and optionally for remote storage). The importance of understanding BitTorrent Sync and its resulting digital investigative implications for law enforcement and forensic investigators will be paramount to future investigations. This paper outlines the client application, its detected network traffic and identifies artefacts that may be of value as evidence for future digital investigations.Comment: Proc. of Digtial Forensics Research Workshop (DFRWS EU 2014

Supporting Computer-supported collaborative work (CSCW) in conceptual design

In order to gain a better understanding of online conceptual collaborative design processes this paper investigates how student designers make use of a shared virtual synchronous environment when engaged in conceptual design. The software enables users to talk to each other and share sketches when they are remotely located. The paper describes a novel methodology for observing and analysing collaborative design processes by adapting the concepts of grounded theory. Rather than concentrating on narrow aspects of the final artefacts, emerging “themes” are generated that provide a broader picture of collaborative design process and context descriptions. Findings on the themes of “grounding – mutual understanding” and “support creativity” complement findings from other research, while important themes associated with “near-synchrony” have not been emphasised in other research. From the study, a series of design recommendations are made for the development of tools to support online computer-supported collaborative work in design using a shared virtual environment

Production spectrum of high energy electrons from high energy cosmic ray collisions

Production spectrum of high energy electrons from high energy cosmic ray collision

Delay in diabetic retinopathy screening increases the rate of detection of referable diabetic retinopathy

Aims - To assess whether there is a relationship between delay in retinopathy screening after diagnosis of Type 2 diabetes and level of retinopathy detected. Methods - Patients were referred from 88 primary care practices to an English National Health Service diabetic eye screening programme. Data for screened patients were extracted from the primary care databases using semi-automated data collection algorithms supplemented by validation processes. The programme uses two-field mydriatic digital photographs graded by a quality assured team. Results - Data were available for 8183 screened patients with diabetes newly diagnosed in 2005, 2006 or 2007. Only 163 with Type 1 diabetes were identified and were insufficient for analysis. Data were available for 8020 with newly diagnosed Type 2 diabetes. Of these, 3569 were screened within 6 months, 2361 between 6 and 11 months, 1058 between 12 and 17 months, 366 between 18 and 23 months, 428 between 24 and 35 months, and 238 at 3 years or more after diagnosis. There were 5416 (67.5%) graded with no retinopathy, 1629 (20.3%) with background retinopathy in one eye, 753 (9.4%) with background retinopathy in both eyes and 222 (2.8%) had referable diabetic retinopathy. There was a significant trend (P = 0.0004) relating time from diagnosis to screening detecting worsening retinopathy. Of those screened within 6 months of diagnosis, 2.3% had referable retinopathy and, 3 years or more after diagnosis, 4.2% had referable retinopathy. Conclusions - The rate of detection of referable diabetic retinopathy is elevated in those who were not screened promptly after diagnosis of Type 2 diabetes