Measuring DNS over TCP in the Era of Increasing DNS Response Sizes: A View from the Edge

The Domain Name System (DNS) is one of the most crucial parts of the Internet. Although the original standard defined the usage of DNS over UDP (DoUDP) as well as DNS over TCP (DoTCP), UDP has become the predominant protocol used in the DNS. With the introduction of new Resource Records (RRs), the sizes of DNS responses have increased considerably. Since this can lead to truncation or IP fragmentation, the fallback to DoTCP as required by the standard ensures successful DNS responses by overcoming the size limitations of DoUDP. However, the effects of the usage of DoTCP by stub resolvers are not extensively studied to this date. We close this gap by presenting a view at DoTCP from the Edge, issuing 12.1M DNS requests from 2,500 probes toward Public as well as Probe DNS recursive resolvers. In our measurement study, we observe that DoTCP is generally slower than DoUDP, where the relative increase in Response Time is less than 37% for most resolvers. While optimizations to DoTCP can be leveraged to further reduce the response times, we show that support on Public resolvers is still missing, hence leaving room for optimizations in the future. Moreover, we also find that Public resolvers generally have comparable reliability for DoTCP and DoUDP. However, Probe resolvers show a significantly different behavior: DoTCP queries targeting Probe resolvers fail in 3 out of 4 cases, and, therefore, do not comply with the standard. This problem will only aggravate in the future: As DNS response sizes will continue to grow, the need for DoTCP will solidify.Comment: Published in ACM SIGCOMM Computer Communication Review Volume 52 Issue 2, April 202

Structures of alternatively spliced isoforms of human ketohexokinase

The structures of the two alternatively spliced isoforms of human ketohexokinase, hepatic KHK-C and peripheral KHK-A, and of the ternary complex of KHK-A with the substrate fructose and AMP-PNP have been solved. The differences between KHK-A and KHK-C resulting from the spliced region are subtle and affect thermostability and probably flexibility; the mutations causing fructosuria were modelled

Structure of the response regulator VicR DNA-binding domain

The structure of the DNA-binding domain of the response regulator VicR from E. faecalis has been solved at 1.9 Å resolution. It is very similar to the related domains from PhoB and OmpR, but differs in two loops that may affect transcription activation or DNA–protein interactions

Purification, crystallization and X-ray structures of the two manganese superoxide dismutases from Caenorhabditis elegans

Two manganese superoxide dismutase enzymes isolated from the eukaryote C. elegans have been characterized and their structures determined. The closely related structures reveal a striking similarity to manganese superoxide dismutase found in humans

National trends in hospital-acquired preventable adverse events after major cancer surgery in the USA

Objectives: While multiple studies have demonstrated variations in the quality of cancer care in the USA, payers are increasingly assessing structure-level and process-level measures to promote quality improvement. Hospital-acquired adverse events are one such measure and we examine their national trends after major cancer surgery. Design: Retrospective, cross-sectional analysis of a weighted-national estimate from the Nationwide Inpatient Sample (NIS) undergoing major oncological procedures (colectomy, cystectomy, oesophagectomy, gastrectomy, hysterectomy, lung resection, pancreatectomy and prostatectomy). The Agency for Healthcare Research and Quality Patient Safety Indicators (PSIs) were utilised to identify trends in hospital-acquired adverse events. Setting: Secondary and tertiary care, US hospitals in NIS Participants: A weighted-national estimate of 2 508 917 patients (>18 years, 1999–2009) from NIS. Primary outcome measures Hospital-acquired adverse events. Results: 324 852 patients experienced ≥1-PSI event (12.9%). Patients with ≥1-PSI experienced higher rates of in-hospital mortality (OR 19.38, 95% CI 18.44 to 20.37), prolonged length of stay (OR 4.43, 95% CI 4.31 to 4.54) and excessive hospital-charges (OR 5.21, 95% CI 5.10 to 5.32). Patients treated at lower volume hospitals experienced both higher PSI events and failure-to-rescue rates. While a steady increase in the frequency of PSI events after major cancer surgery has occurred over the last 10 years (estimated annual % change (EAPC): 3.5%, p<0.001), a concomitant decrease in failure-to-rescue rates (EAPC −3.01%) and overall mortality (EAPC −2.30%) was noted (all p<0.001). Conclusions: Over the past decade, there has been a substantial increase in the national frequency of potentially avoidable adverse events after major cancer surgery, with a detrimental effect on numerous outcome-level measures. However, there was a concomitant reduction in failure-to-rescue rates and overall mortality rates. Policy changes to improve the increasing burden of specific adverse events, such as postoperative sepsis, pressure ulcers and respiratory failure, are required

GNOSIS: the first instrument to use fibre Bragg gratings for OH suppression

GNOSIS is a prototype astrophotonic instrument that utilizes OH suppression fibres consisting of fibre Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47-1.7 microns. GNOSIS was commissioned at the 3.9-meter Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibres, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput and excellent suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS and IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise-dominated. OH suppression fibres could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibres paired with a fibre-fed spectrograph will at least provide a real benefits at low resolving powers.Comment: 15 pages, 13 figures, accepted to A

The Sydney-AAO Multi-object Integral field spectrograph (SAMI)

We demonstrate a novel technology that combines the power of the multi-object spectrograph with the spatial multiplex advantage of an integral field spectrograph (IFS). The Sydney-AAO Multi-object IFS (SAMI) is a prototype wide-field system at the Anglo-Australian Telescope (AAT) that allows 13 imaging fibre bundles ("hexabundles") to be deployed over a 1-degree diameter field of view. Each hexabundle comprises 61 lightly-fused multimode fibres with reduced cladding and yields a 75 percent filling factor. Each fibre core diameter subtends 1.6 arcseconds on the sky and each hexabundle has a field of view of 15 arcseconds diameter. The fibres are fed to the flexible AAOmega double-beam spectrograph, which can be used at a range of spectral resolutions (R=lambda/delta(lambda) ~ 1700-13000) over the optical spectrum (3700-9500A). We present the first spectroscopic results obtained with SAMI for a sample of galaxies at z~0.05. We discuss the prospects of implementing hexabundles at a much higher multiplex over wider fields of view in order to carry out spatially--resolved spectroscopic surveys of 10^4 to 10^5 galaxies.Comment: 24 pages, 16 figures. Accepted by MNRA

Degradation of the chemotherapy drug 5-fouorouracil on medical-grade silver surfaces

The degradation of the chemotherapy drug 5-fluorouracil by a non-pristine metal surfaces is studied. Using density functional theory, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy we show that the drug is entirely degraded by medical-grade silver surfaces, already at body temperature, and that all of the fluorine has left the molecule, presumably as HF. Remarkably, this degradation is even more severe than that reported previously for 5-fluorouracil on a pristine monocrystalline silver surface (in which case 80% of the drug reacted at body temperature) [1]. We conclude that the observed reaction is due to a reaction pathway, driven by H to F attraction between molecules on the surface, which results in the direct formation of HF; a pathway which is favoured when competing pathways involving reactive Ag surface sites are made unavailable by environmental contamination. Our measurements indicate that realistically cleaned, non-pristine silver alloys, which are typically used in medical applications, can result in severe degradation of 5-fluorouracil, with the release of HF – a finding which may have important implications for the handling of chemotherapy drugs