Optimising node selection probabilities in multi-hop M/D/1 queuing networks to reduce latency of Tor

In this paper the expected cell latency for multi-hop M/D/1 queuing networks, where users choose nodes randomly according to some distribution, is derived. It is shown that the resulting optimisation surface is convex, and thus gradient based methods can be used to find the optimal node assignment probabilities. This is applied to a typical snapshot of the Tor anonymity network at 50%usage, and leads to a reduction in expected cell latency from 11.7 ms using the original method of assigning node selection probabilities to 1.3 ms. It is also shown that even if the usage is not known exactly, the proposed method still leads to an improvement.This is the accepted manuscript version. The final version is available from IET at http://digital-library.theiet.org/content/journals/10.1049/el.2014.2136

Range extension and reproduction of the barnacle Balanus perforatus in the eastern English Channel

The distribution of the warm-water barnacle, Balanus perforatus, was surveyed along the south coast of England and the north-east coast of France between 1993 and 2001, repeating work carried out between the 1940s and 1960s. The species has recovered from catastrophic mortality during the severe winter of 1962–1963 and was found over 120 km (UK) and 190 km (France) east of previous records on both sides of the Channel. The presence of the species in the eastern Channel refutes suggestions in the 1950s that larvae, and hence adults, would not be found east of the Isle of Wight because of reproductive sterility close to the limits of distribution. Brooding of specimens translocated to Bembridge, Isle of Wight, commenced in May, earlier than previously observed in British waters, and continued until September. The stage of embryo development at Bembridge in mid-August was comparable to that of the large population at Lyme Regis, Dorset 100 km further west. However the size of brood per standard body weight was greater at Lyme Regis. Factors influencing the rate of colonization and further geographic range extension of the species as a possible result of climate change, are discussed

Optimising node selection probabilities in multi-hop M/D/1 queuing networks to reduce latency of Tor

The expected cell latency for multi-hop M/D/1 queuing networks, where users choose nodes randomly according to some distribution, is derived. It is shown that the resulting optimisation surface is convex, and thus gradient-based methods can be used to find the optimal node assignment probabilities. This is applied to a typical snapshot of the Tor anonymity network at 50% usage, and leads to a reduction in expected cell latency from 11.7 ms using the original method of assigning node selection probabilities to 1.3 ms. It is also shown that even if the usage is not known exactly, the proposed method still leads to an improvement

Deformation mechanisms in ionic liquid spun cellulose fibers

This is the final version of the article. Available from the publisher via the DOI in this record.The molecular deformation and crystal orientation of a range of next generation regenerated cellulose fibers, produced from an ionic liquid solvent spinning system, are correlated with macroscopic fiber properties. Fibers are drawn at the spinning stage to increase both molecular and crystal orientation in order to achieve a high tensile strength and Young’s modulus for potential use in engineering applications. Raman spectroscopy was utilized to quantify both molecular strain and orientation of fibers deformed in tension. X-ray diffraction was used to characterize crystal orientation of single fibers. These techniques are shown to provide complimentary information on the microstructure of the fibers. A shift in the position of a characteristic Raman band, initially located at ∼1095 cm−1, emanating from the backbone structure of the cellulose polymer chains was followed under tensile deformation. It is shown that the shift rate of this band with respect to strain increases with the draw ratio of the fibers, indicative of an increase in the axial molecular alignment and subsequent deformation of the cellulose chains. A linear relationship between the Raman band shift rate and the modulus was established, indicating that the fibers possess a series aggregate structure of aligned crystalline and amorphous domains. Wide-angle X-ray diffraction data show that crystal orientation increases with an increase in the draw ratio, and a crystalline chain slip model was used to fit the change in orientation with fiber draw ratio. In addition to this a new model is proposed for a series aggregate structure that takes into better account the molecular deformation of the fibers. Using this model a prediction for the crystal modulus of a cellulose-II structure is made (83 GPa) which is shown to be in good agreement with other experimental approaches for its determination.The Engineering and Physical Sciences Research Council (EPSRC) is acknowledged for funding provided under Grant No. EP/L017679/1

Multiple sclerosis susceptibility alleles in African Americans.

Multiple sclerosis (MS) is an autoimmune demyelinating disease characterized by complex genetics and multifaceted gene-environment interactions. Compared to whites, African Americans have a lower risk for developing MS, but African Americans with MS have a greater risk of disability. These differences between African Americans and whites may represent differences in genetic susceptibility and/or environmental factors. SNPs from 12 candidate genes have recently been identified and validated with MS risk in white populations. We performed a replication study using 918 cases and 656 unrelated controls to test whether these candidate genes are also associated with MS risk in African Americans. CD6, CLEC16a, EVI5, GPC5, and TYK2 contained SNPs that are associated with MS risk in the African American data set. EVI5 showed the strongest association outside the major histocompatibility complex (rs10735781, OR=1.233, 95% CI=1.06-1.43, P-value=0.006). In addition, RGS1 seems to affect age of onset whereas TNFRSF1A seems to be associated with disease progression. None of the tested variants showed results that were statistically inconsistent with the effects established in whites. The results are consistent with shared disease genetic mechanisms among individuals of European and African ancestry

A method for encoding clinical datasets with SNOMED CT

<p>Abstract</p> <p>Background</p> <p>Over the past decade there has been a growing body of literature on how the Systematised Nomenclature of Medicine Clinical Terms (SNOMED CT) can be implemented and used in different clinical settings. Yet, for those charged with incorporating SNOMED CT into their organisation's clinical applications and vocabulary systems, there are few detailed encoding instructions and examples available to show how this can be done and the issues involved. This paper describes a heuristic method that can be used to encode clinical terms in SNOMED CT and an illustration of how it was applied to encode an existing palliative care dataset.</p> <p>Methods</p> <p>The encoding process involves: identifying input data items; cleaning the data items; encoding the cleaned data items; and exporting the encoded terms as output term sets. Four outputs are produced: the SNOMED CT reference set; interface terminology set; SNOMED CT extension set and unencodeable term set.</p> <p>Results</p> <p>The original palliative care database contained 211 data elements, 145 coded values and 37,248 free text values. We were able to encode ~84% of the terms, another ~8% require further encoding and verification while terms that had a frequency of fewer than five were not encoded (~7%).</p> <p>Conclusions</p> <p>From the pilot, it would seem our SNOMED CT encoding method has the potential to become a general purpose terminology encoding approach that can be used in different clinical systems.</p

Titin genotype is associated with skeletal muscle fascicle length in recreationally active men and running performance in habitually trained marathon runners

Objectives The titin gene (TTN) encodes the largest described protein to date and, due to its size, provides a molecular blueprint for the organisation and assembly of the muscle sarcomere. Differences in sarcomere length, due to the expression of different titin isoforms, have been observed previously and may influence muscle fascicle length, which could provide an advantage for running performance. Thus, the aim of this study was to investigate if the TTN rs10497520 polymorphism was associated with muscle fascicle length in recreationally active men and marathon personal best time in elite male marathon runners, and to investigate any differences in genotype frequency between RA and MR.Methods The sample comprised 278 healthy, unrelated Caucasian men who all gave written consent to take part. Participants were categorised as either recreationally active [RA; n = 137; age = 20.7 (2.7) yr; height = 1.79 (0.06) m; mass = 75.3 (10.1) kg] or marathon runners [MR; n = 141; age = 34.9 (7.8) yr; height = 1.79 (0.07) m; mass = 66.5 (6.7) kg]. MR comprised Olympic, international and national level athletes, who had all achieved marathon personal best times under 2 hr 36 mins. Resting fascicle length of the vastus lateralis muscle was assessed in vivo using B-mode ultrasonography at 50% of muscle length in RA only. All participants provided either a whole blood, saliva or buccal cell sample, from which DNA was isolated and genotyped using real-time polymerase chain reaction. Independent samples t-tests were used to determine any genotype-dependent differences in fascicle length in RA and marathon personal best time in MR. Pearson’s chi-square tests were conducted to compare genotype frequencies between RA and MR.Results Vastus lateralis fascicle length was 10.4% longer in CC homozygotes than CT heterozygotes (P = 0.003) in RA. In the absence of any TT homozygotes, reflective of the low T-allele frequency within Caucasian populations, it is unclear if fascicle length for this group would have been smaller still. No differences in genotype frequency between the RA and MR groups were observed (P = 0.500), however, within the MR group the T-allele carriers demonstrated marathon personal best times 2 min 25 s faster than CC homozygotes (P = 0.020).Conclusions These results suggest that the T-allele at rs10497520 in the TTN gene is associated with shorter skeletal muscle fascicle length and conveys an advantage for marathon running performance in habitually trained men

The presence of the proteolysis-inducing factor in urine does not predict the malignancy of a pancreatic tumour

BACKGROUND: The proteolysis-inducing factor (PIF) was identified as a tumour product in various gastrointestinal cancers. A previous study in pancreatic cancer patients suggested PIF expression as a tumour marker, which is not related to tumour size. We hypothesized that PIF could be a useful marker to exclude benign pancreatic tumors, as chronic pancreatitis with a pancreatic mass. METHODS: Urine of patients with a pancreatic mass of uncertain malignancy was investigated for PIF expression by Western blot. Sufficient urine protein for analysis was available in 59 patients. The diagnosis was established by histology in 54 patients and by follow up in five patients with chronic pancreatitis. In addition, serum CA19-9 was measured. RESULTS: The sensitivity (specifity) for the detection of a malignant pancreatic tumour was 90% (75%) and 54% (71%) for CA19-9 and PIF, respectively. The sensitivity (specifity) for the distinction of pancreatic cancer from chronic pancreatitis was 89% (80%) and 57% (63%) for CA19-9 and PIF, respectively. CONCLUSION: Evaluation of PIF in urine is of no diagnostic value in patients with a pancreatic mass of unknown malignancy

No association between tendon-related genes and performance in elite European Caucasian marathon runners.

Tendons adapt to load under normal physiological conditions, however, under extreme loading conditions, such as those experienced by elite endurance athletes, incomplete adaptation may occur and cause injury. The prevalence of tendinopathies in elite endurance athletes is approximately 50%, thus variability exists in an athlete's tolerance to extreme loading. A number of intrinsic and extrinsic factors contribute to modulating injury risk, some of which are modifiable and others, such as genetic variants, are non-modifiable. It was hypothesized that elite marathon runners would possess a genotype associated with enhanced tendon function, and thus protective against tendinopathy. Here, we compared the genotype frequencies of six genetic variants (COL1A1 rs1800012, VEGFA rs699947, TIMP2 rs4789932, MMP3 rs591058, MMP3 rs650108, MMP3 rs679620), previously associated with tendinopathy, in elite (men <2 h 30 min, n = 109, women <3 h 00 min, n = 99) and sub-elite (men 2 h 30 min-2 h 45 min, n = 189; women 3 h 00 min-3 h 15 min, n = 71) marathon runners with those of a non-athletic control group (n = 564). Genotype associations with marathon personal best time in the athlete group were also investigated. All participants provided either a whole blood, saliva or buccal cell sample, from which DNA was isolated, and genotyped for all six variants using real-time PCR. Genotype frequency differed between athletes and controls for TIMP2 rs4789932 (TT = 17%, CT = 51%, CC = 32% vs. TT = 22%, CT = 42%, CC = 36%, respectively; χ2 = 8.135, P = 0.017) only. However, there was no clear difference in allele frequencies between groups for TIMP2 rs4789932. MMP3 rs650108 genotype frequency differed between female elite and sub-elite athletes (χ2 = 11.913, P = 0.003) only and, as hypothesized, it was the “risk” A-allele that was ~10% less frequent in the elite, than sub-elite athletes. Following combination of all genotype data into a total genotype score, no differences in score between athletes and controls were observed (t = 2.93, P = 0.769). Similarly, no associations between total genotype score and marathon personal best time in male and female runners were observed (r ≤ 0.066, P ≥ 0.394). The results suggest elite marathon runners do not possess a genotype protective against tendinopathy, at least for the tendon-related genetic variants we investigated