On reducing mesh delay for peer-to-peer live streaming

Peer-to-peer (P2P) technology has emerged as a promising scalable solution for live streaming to large group. In this paper, we address the design of overlay which achieves low source-to-peer delay, is robust to user churn, accommodates of asymmetric and diverse uplink bandwidth, and continuously improves based on existing user pool. A natural choice is the use of mesh, where each peer is served by multiple parents. Since the peer delay in a mesh depends on its longest path through its parents, we study how to optimize such delay while meeting a certain streaming rate requirement. We first formulate the minimum delay mesh problem and show that it is NP-hard. Then we propose a centralized heuristic based on complete knowledge which serves as our benchmark and optimal solution for all the other schemes under comparison. Our heuristic makes use of the concept of power in network given by the ratio of throughput and delay. By maximizing the network power, our heuristic achieves very low delay. We then propose a simple distributed algorithm where peers select their parents based on the power concept. The algorithm makes continuous improvement on delay until some minimum delay is reached. Simulation results show that our distributed protocol performs close to the centralized one, and substantially outperforms traditional and state-of-the-art approaches

Use of the tetrazolium salt MTT to measure cell viability effects of the bacterial antagonist Lysobacter enzymogenes on the filamentous fungus Cryphonectria parasitica

Despite substantial interest investigating bacterial mechanisms of fungal growth inhibition, there are few methods available that quantify fungal cell death during direct interactions with bacteria. Here we describe an in vitro cell suspension assay using the tetrazolium salt MTT as a viability stain to assess direct effects of the bacterial antagonist Lysobacter enzymogenes on hyphal cells of the filamentous fungus Cryphonectria parasitica. The effects of bacterial cell density, fungal age and the physiological state of fungal mycelia on fungal cell viability were evaluated. As expected, increased bacterial cell density correlated with reduced fungal cell viability over time. Bacterial effects on fungal cell viability were influenced by both age and physiological state of the fungal mycelium. Cells obtained from 1-week-old mycelia lost viability faster compared with those from 2-week-old mycelia. Likewise, hyphal cells obtained from the lower layer of the mycelial pellicle lost viability more quickly compared with cells from the upper layer of the mycelial pellicle. Fungal cell viability was compared between interactions with L. enzymogenes wildtype strain C3 and a mutant strain, DCA, which was previously demonstrated to lack in vitro antifungal activity. Addition of antibiotics eliminated contributions to MTT-formazan production by bacterial cells, but not by fungal cells, demonstrating that mutant strain DCA had lost complete capacity to reduce fungal cell viability. These results indicate this cell suspension assay can be used to quantify bacterial effects on fungal cells, thus providing a reliable method to differentiate strains during bacterial/fungal interactions

Novel DNA methylation profiles associated with key gene regulation and transcription pathways in blood and placenta of growth-restricted neonates

BB/H012494/1/ Biotechnology and Biological Sciences Research Counci

Niobium based intermetallics as a source of high-current/high-magnetic field superconductors

The article is focused on low temperature intermetallic A15 superconducting wires development for Nuclear Magnetic Resonance, NMR, and Nuclear Magnetic Imaging, MRI, magnets and also on cryogen-free magnets. There are many other applications which would benefit from new development such as future Large Hadron Collider to be built from A15 intermetallic conductors. This paper highlights the current status of development of the niobium based intermetallics with special attention to Nb 3 (Al 1-x, Ge x). Discussion is focused on the materials science aspects of conductor manufacture, such as b-phase (A15) formation, with particular emphasis on the maximisation of the superconducting parameters, such as critical current density, Jc, critical temperature, Tc, and upper critical field, Hc2 . Many successful manufacturing techniques of the potential niobium-aluminide intermetallic superconducting conductors, such as solid-state processing, liquid-solid processing, rapid heating/cooling processes, are described, compared and assessed. Special emphasis has been laid on conditions under which the Jc (B) peak effect occurs in some of the Nb3(Al,Ge) wires. A novel electrodeoxidizing method developed in Cambridge whereby the alloys and intermetallics are produced cheaply making all superconducting electromagnetic devices, using low cost LTCs, more cost effective is presented.This new technique has potential to revolutionise the existing superconducting industry enabling reduction of cost orders of magnitude.Comment: Paper presented at EUCAS'01 conference, Copenhagen, 26-30 August 200

Progression of renal cell carcinoma is inhibited by genistein and radiation in an orthotopic model

BACKGROUND: We have previously reported the potentiation of radiotherapy by the soy isoflavone genistein for prostate cancer using prostate tumor cells in vitro and orthotopic prostate tumor models in vivo. However, when genistein was used as single therapy in animal models, it promoted metastasis to regional para-aortic lymph nodes. To clarify whether these intriguing adverse effects of genistein are intrinsic to the orthotopic prostate tumor model, or these results could also be recapitulated in another model, we used the orthotopic metastatic KCI-18 renal cell carcinoma (RCC) model established in our laboratory. METHODS: The KCI-18 RCC cell line was generated from a patient with papillary renal cell carcinoma. Following orthotopic renal implantation of KCI-18 RCC cells and serial in vivo kidney passages in nude mice, we have established a reliable and predictable metastatic RCC tumor model. Mice bearing established kidney tumors were treated with genistein combined with kidney tumor irradiation. The effect of the therapy was assessed on the primary tumor and metastases to various organs. RESULTS: In this experimental model, the karyotype and histological characteristics of the human primary tumor are preserved. Tumor cells metastasize from the primary renal tumor to the lungs, liver and mesentery mimicking the progression of RCC in humans. Treatment of established kidney tumors with genistein demonstrated a tendency to stimulate the growth of the primary kidney tumor and increase the incidence of metastasis to the mesentery lining the bowel. In contrast, when given in conjunction with kidney tumor irradiation, genistein significantly inhibited the growth and progression of established kidney tumors. These findings confirm the potentiation of radiotherapy by genistein in the orthotopic RCC model as previously shown in orthotopic models of prostate cancer. CONCLUSION: Our studies in both RCC and prostate tumor models demonstrate that the combination of genistein with primary tumor irradiation is a more effective and safer therapeutic approach as the tumor growth and progression are inhibited both in the primary and metastatic sites

Readmission to intensive care: development of a nomogram for individualising risk

Background: Readmission to intensive care during the same hospital stay has been associated with a greater risk of in-hospital mortality and has been suggested as a marker ofquality of care. There is lack of published research attempting to develop clinical prediction tools that individualise the risk of readmission to the intensive care unit during the same hospital stay. Objective: To develop a prediction model using an inception cohort of patients surviving an initial ICU stay. Design, setting and participants: The study was conducted at Liverpool Hospital, Sydney. An inception cohort of 14 952 patients aged 15 years or more surviving an initial ICU stay and transferred to general wards in the study hospital between 1 January 1997 and 31 December 2007 was used to develop the model. Binary logistic regression was used to develop the prediction model and anomogram was derived to individualise the risk of readmission to the ICU during the same hospital stay. Main outcome measure: Readmission to the ICU during the same hospital stay.Results: Among members of the study cohort there were 987 readmissions to ICU during the study period. Compared with patients not readmitted to the ICU, patients who were readmitted were more likely to have had ICU stays of at least 7 days (odds ratio [OR], 2.2 [95% CI, 1.85-2.56]); non-elective initial admission to the ICU (OR, 1.7[95% CI, 1.44-2.08]); and acute renal failure (OR, 1.6 [95%CI, 0.97-2.47]). Patients admitted to the ICU from the operating theatre or recovery ward had a lower risk of readmission to ICU than those admitted from general wards, the emergency department or other hospitals. The maximum error between observed frequencies and predicted probabilities of readmission to ICU was estimatedto be 3%. The area under the receiver operating characteristic curve of the final model was 0.66.Conclusion: We have developed a practical clinical tool toindividualise the risk of readmission to the ICU during the same hospital stay in patients who survive an initial episodeof intensive care

Nova multiwavelength light curves: predicting UV precursor flashes and pre-maximum halts

The dramatic brightenings of classical novae have yielded rich data sets of detailed light curves. Modelling these light curves is a challenge for any theory of classical novae. We have used our extended grid of nova outburst calculations to predict the luminosities of erupting novae expected in three electromagnetic bands – the visual, the near UV and the X-ray. Our models predict and explain many features of novae before eruption, as well as detailed characterizations of nova outbursts and post-nova declines. The evolutionary time-scales of eruption features vary by orders of magnitude, and depend on the basic nova parameters: white dwarf mass, luminosity and accretion rate. However, all light curves are found to share common features. Some of these features are unique to only one electromagnetic passband, while others show up in two, or in all three of the analysed bands. One extraordinary feature, common to all of our low-mass white dwarfs (0.65 M_⊙) novae, is that all exhibit a sharp rise followed by a more gradual decline in the near-UV luminosity, prior to the eruption in the visual luminosity. This is because the expansion of the outer layers lags behind the rise in bolometric luminosity. These predicted precursor-UV-flashes last between a few hours and a few days, and the predicted luminosity increase is between ∼0.5 and ∼3 mag. These flashes should be easily observable if a nova event is detected early and its time coverage is dense. Many observed novae exhibit a pre-maximum halt, and this feature is found in all three electromagnetic bands of many, but not all, of our nova models. We explain the presence or absence of pre-maximum halts as due to changes in the convective energy transfer regime. Finally we note cases where the maximum visual magnitude reaches as high as −8.5 mag for low-mass white dwarfs. This re-emphasizes the fact that white dwarf mass is not always the determining factor in setting a nova's peak luminosity

Electron spin coherence in semiconductors: Considerations for a spin-based solid state quantum computer architecture

We theoretically consider coherence times for spins in two quantum computer architectures, where the qubit is the spin of an electron bound to a P donor impurity in Si or within a GaAs quantum dot. We show that low temperature decoherence is dominated by spin-spin interactions, through spectral diffusion and dipolar flip-flop mechanisms. These contributions lead to 1-100 $\mu$s calculated spin coherence times for a wide range of parameters, much higher than former estimates based on $T_{2}^{*}$ measurements.Comment: Role of the dipolar interaction clarified; Included discussion on the approximations employed in the spectral diffusion calculation. Final version to appear in Phys. Rev.