Dafny meets the Verification Benchmarks Challenge

A suite of verification benchmarks for software verification tools and techniques, presented at VSTTE 2008 [11], provides an initial catalogue of benchmark challenges for the Verified Software Initiative. This paper presents solutions to these eight benchmarks using the language and verifier Dafny. A Dafny program includes specifications, code, inductive invariants, and termination metrics. Each of the eight programs is fed to the Dafny verifier, which without further user interaction automatically performs the verification in a few seconds

Optical properties of mercury ion thruster exhausts and implications for science instruments

Emission from the exhaust plume of a 30 cm mercury ion thruster was measured from 160 to 600 nm as a function of axial and radial distance from the thruster discharge chamber. The spectrally dispersed absolute intensities were used to construct an empirical volume rate function. The function was integrated along a typical instrument field of view, and the resulting apparent brightness was compared with instrument sensitivities to evaluate the extent of optical interference. Most of the emitted radiation came from UV lines of excited mercury atoms and ions, with no observable continuum emission. The intensity levels degraded rapidly with distance from the thruster so that optical interference was negligible for fields of view not intercepting the beam axis. The operation of only one instrument, a zodiacal photopolarimeter, was considered incompatible with simultaneous thruster operation

Circulating T cell subsets are altered in individuals with chronic spinal cord injury

Traumatic spinal cord injury (SCI) induces changes in the immune system, both acutely and chronically. To better understand changes in the chronic phase of SCI, we performed a prospective, observational study in a research institute and Department of Physical Medicine and Rehabilitation of an academic medical center to examine immune system parameters, including peripheral immune cell populations, in individuals with chronic SCI as compared to uninjured individuals. Here, we describe the relative frequencies of T cell populations in individuals with chronic SCI as compared to uninjured individuals. We show that the frequency of CD3+ and CD3+ CD4+ T cells are decreased in individuals with chronic SCI, although activated (HLA-DR+) CD4+ T cells are elevated in chronic SCI. We also examined regulatory T cells (Tregs), defined as CD3+ CD4+ CD25+ CD127lo and CCR4+, HLA-DR+ or CCR4+ HLA-DR+. To our knowledge, we provide the first evidence that CCR4+, HLA-DR+ or CCR4+ HLA-DR+ Tregs are expanded in individuals with SCI. These data support additional functional studies of T cells isolated from individuals with chronic SCI, where alterations in T cell homeostasis may contribute to immune dysfunction, such as immunity against infections or the persistence of chronic inflammation

Hackflex: low-cost, high-throughput, Illumina Nextera Flex library construction.

We developed a low-cost method for the production of Illumina-compatible sequencing libraries that allows up to 14 times more libraries for high-throughput Illumina sequencing to be generated for the same cost. We call this new method Hackflex. The quality of library preparation was tested by constructing libraries from Escherichia coli MG1655 genomic DNA using either Hackflex, standard Nextera Flex (recently renamed as Illumina DNA Prep) or a variation of standard Nextera Flex in which the bead-linked transposase is diluted prior to use. In order to test the library quality for genomes with a higher and a lower G+C content, library construction methods were also tested on Pseudomonas aeruginosa PAO1 and Staphylococcus aureus ATCC 25923, respectively. We demonstrated that Hackflex can produce high-quality libraries and yields a highly uniform coverage, equivalent to the standard Nextera Flex kit. We show that strongly size-selected libraries produce sufficient yield and complexity to support de novo microbial genome assembly, and that assemblies of the large-insert libraries can be much more contiguous than standard libraries without strong size selection. We introduce a new set of sample barcodes that are distinct from standard Illumina barcodes, enabling Hackflex samples to be multiplexed with samples barcoded using standard Illumina kits. Using Hackflex, we were able to achieve a per-sample reagent cost for library prep of A$7.22 (Australian dollars) (US$5.60; UK £3.87, £1=A$1.87), which is 9.87 times lower than the standard Nextera Flex protocol at advertised retail price. An additional simple modification and further simplification of the protocol by omitting the wash step enables a further price reduction to reach an overall 14-fold cost saving. This method will allow researchers to construct more libraries within a given budget, thereby yielding more data and facilitating research programmes where sequencing large numbers of libraries is beneficial

Hackflex: low cost Illumina sequencing library construction for high sample counts

ABSTRACT We developed Hackflex, a low-cost method for the production of Illumina-compatible sequencing libraries that allows up to 11 times more libraries for high-throughput Illumina sequencing to be generated at a fixed cost. We call this new method Hackflex. Quality of library preparation was tested by constructing libraries from E. coli MG1655 genomic DNA using either Hackflex, standard Nextera Flex or a variation of standard Nextera Flex in which the bead-linked transposase is diluted prior to use. We demonstrated that Hackflex can produce high quality libraries and yields a highly uniform coverage, equivalent to the standard Nextera Flex kit. Using Hackflex, we were able to achieve a per sample reagent cost of library prep of A$8.66, which is 8.23 times lower than the Standard Nextera Flex protocol at advertised retail price. An additional simple modification to the protocol enables a further price reduction of up to 11 fold or about A$6.50/sample. This method will allow researchers to construct more libraries within a given budget, thereby yielding more data and facilitating research programs where sequencing large numbers of libraries is beneficial

Multiple column high-throughput e-beam inspection (EBI)

Single-column e-beam systems are used in production for the detection of electrical defects, but are too slow to be used for the detection of small physical defects, and can't meet future inspection requirements. This paper presents a multiple-column e-beam technology for high throughput wafer inspection. Multibeam has developed all-electrostatic columns for high-resolution imaging. The elimination of magnetic coils enables the columns to be small; e-beam deflection is faster in the absence of magnetic hysteresis. Multiple miniature-columns are assembled in an array. An array of 100 columns covers the entire surface of a 300mm wafer, affording simultaneous cross-wafer sampling. Column performance simulations and system architecture are presented. Also provided are examples of high throughput, more efficient, multiple-column wafer inspection

The weak password problem: chaos, criticality, and encrypted p-CAPTCHAs

Vulnerabilities related to weak passwords are a pressing global economic and security issue. We report a novel, simple, and effective approach to address the weak password problem. Building upon chaotic dynamics, criticality at phase transitions, CAPTCHA recognition, and computational round-off errors we design an algorithm that strengthens security of passwords. The core idea of our method is to split a long and secure password into two components. The first component is memorized by the user. The second component is transformed into a CAPTCHA image and then protected using evolution of a two-dimensional dynamical system close to a phase transition, in such a way that standard brute-force attacks become ineffective. We expect our approach to have wide applications for authentication and encryption technologies.Comment: 5 pages, 6 figer

Discussions of Life Expectancy Moderate Relationships between Prognosis and Anxiety or Depression in Men with Advanced Cancer

Purpose: Oncologists avoid prognostic discussions due to concerns about increasing patients' anxiety or depression. We sought to determine if perceived prognosis or extent of prognostic discussions predicted anxiety or depression and whether prognostic discussions moderated the relationship between prognosis and anxiety or depression. Methods: Men with advanced cancer and their oncologists estimated the likelihood of survival at 6 months and reported extent of prognostic discussions. Anxiety and depression were measured by the Hospital Anxiety and Depression Scale (HADS). Results: Men who died within 6 months reported higher scores on depression but not anxiety. Men who estimated a lower (10%–75%) likelihood of surviving at least 6 months were more depressed and anxious than men who estimated a higher (>90%) likelihood of survival. A similar relationship was seen with oncologists' prognostications. Men who reported having had full prognostic discussions with their oncologist had less depression compared with men who reported having had brief or no discussions. Men for whom the oncologists reported a full discussion had greater anxiety. The relationships between patient-perceived prognosis and depression or anxiety were moderated by extent of prognostic discussions as reported by the patient or oncologist, respectively. Conclusion: Full prognostic discussions are associated with less depression among men who perceive a poor prognosis. Anxiety is increased in men if the oncologists report a full discussion. Oncologists should engage in prognostic discussions but assess for increased anxiety to facilitate coping with advanced cancer

Virtual Reality for early education : a study

This paper investigates the use of Virtual Reality (VR) as a tool for cultural heritage learning, using St Andrews Cathedral as the subject matter. As part of a module focused on local history, first year secondary school pupils in a school in the town of St Andrews took part in virtual tours of the Cathedral as it stood in the 14th Century using the Samsung Gear VR, Google Cardboard, Oculus Rift, computer screen and Xbox controller, and answered questions aimed to elicit their experiences with the various systems. The system design and implementation is presented and the findings, observations and lessons learnt from the study are discussed.Postprin