168 research outputs found
Split Distributed Computing in Wireless Sensor Networks
We designed a novel method intended to improve the performance of distributed computing in wireless sensor networks. Our proposed method is designed to rapidly increase the speed of distributed computing and decrease the number of the messages required for a network to achieve the desired result. In our analysis, we chose Average consensus algorithm. In this case, the desired result is that every node achieves the average value calculated from all the initial values in the reduced number of iterations. Our method is based on the idea that a fragmentation of a network into small geographical structures which execute distributed calculations in parallel significantly affects the performance
The Distributed Convergence Classifier Using the Finite Difference
The paper presents a novel distributed classifier of the convergence, which allows to detect the convergence/the divergence of a distributed converging algorithm. Since this classifier is supposed to be primarily applied in wireless sensor networks, its proposal makes provision for the character of these networks. The classifier is based on the mechanism of comparison of the forward finite differences from two consequent iterations. The convergence/the divergence is classifiable only in terms of the changes of the inner states of a particular node and therefore, no message redundancy is required for its proper functionality
A MESSAGE FAILURE ANALYSIS OF SYSTEMS EXECUTING AVERAGE CONSENSUS ALGORITHM
A communication failure is an aspect which may affect a whole system so significantly that it is unable to provide its functionality any longer. In this paper, we have implemented average consensus algorithm into 30 distributed systems and focused on examining the effect of a message delivery failure modeled by Bernoulli distribution. We modified the probability of a failure occurrence and examined the effect of these changes on the number of the iterations necessary for a distributed system to achieve the consensus and the deviation of the final values from the expected ones
The Analysis Of The Push-sum Protocol In Various Distributed Systems
In this paper, we have focused on an analysis of the push-sum protocol in various topologies. We analyzed the behavior of distributed systems forming a tree, a star, a ring and a fully-connected mesh topology. We also examined the influence of stochastic features of the push-sum protocol on the properties of this protocol and the convergence rates in the particular topologies
Nerve diffusion tensor imaging
Diffusion tensor imaging (DTI) is a magnetic resonance imaging technique
that in vivo visualises random translational movement of water molecules. DTI has inherent difficulties with low signal-to-noise ratio, sensitivity to patient motion, field inhomogeneities and fast T2 relaxation. It has been used in the central nervous system, although it has not been assessed in the peripheral nervous system. The aim of this thesis was to investigate if DTI in peripheral nerves was feasible, and if so, to investigate clinical implications.
Study I showed that in healthy volunteers the peripheral nerves, the sciatic
nerves, could be visualised in vivo using DTI and fiber tracking. Study II showed that sciatic nerves, including their division into the tibial and common fibular nerves, have a characteristic diffusion pattern with most impaired diffusion perpendicular to the nerve direction. This allowed nerves, excluding other tissues and artifacts, to be visualised using a novel approach called diffusion-direction- dependent imaging and with a simple unidirectional diffusion maximum-intensity projection approach. Study III showed that the olfactory bulbs (OBs) and olfactory tracts could be visualised in vivo using DTI and fiber tracking. In Study IV, Parkinsonâs disease (PD) patients with impaired olfaction were evaluated with DTI of the OBs. A novel approach of DTI was used, taking advantage of the techniqueâs inherent directional information, for region of interest placement and diffusion measurements in the OBs. In the PD patient group diffusion was altered in the OBs, compared to healthy controls. This was hypothesised, since α-synuclein inclusions and Lewy neurites interfering with nerve structure have been detected in the OBs. However, the coefficient of variation between two identical DTI series was high, due to the small size of the OBs and their location in an area susceptible to artifacts, and the difference between the groups was statistically significant only for the first of two series. In Study V, patients of the Swedish âHuddinge Spinocerebellar ataxia (SCA) Familyâ with peripheral neuropathy, were evaluated with DTI of a peripheral nerve. Diffusion alterations were found in peripheral nerves in SCA patients, compared to healthy controls, which was statistically significant.
In conclusion, DTI in peripheral nerves is feasible and can be used to detect
diffusion alterations in OBs in PD patients and in peripheral nerves in SCA patients with peripheral neuropathy
Accuracy in local staging of prostate cancer by adding a three-dimensional T2-weighted sequence with radial reconstructions in magnetic resonance imaging.
BACKGROUND: The evidence supporting the use of magnetic resonance imaging (MRI) in prostate cancer detection has been established, but its accuracy in local staging is questioned. PURPOSE: To investigate the additional value of multi-planar radial reconstructions of a three-dimensional (3D) T2-weighted (T2W) MRI sequence, intercepting the prostate capsule perpendicularly, for improving local staging of prostate cancer. MATERIAL AND METHODS: Preoperative, bi-parametric prostate MRI examinations in 94 patients operated between June 2014 and January 2015 where retrospectively reviewed by two experienced abdominal radiologists. Each patient was presented in two separate sets including diffusion-weighted imaging, without and with the 3D T2W set that included radial reconstructions. Each set was read at least two months apart. Extraprostatic tumor extension (EPE) was assessed according to a 5-point grading scale. Sensitivity and specificity for EPE was calculated and presented as receiver operating characteristics (ROC) with area under the curve (AUC), using histology from whole-mount prostate specimen as gold standard. Inter-rater agreement was calculated for the two different reading modes using Cohen's kappa. RESULTS: The AUC for detection of EPE for Readers 1 and 2 in the two-dimensional (2D) set was 0.70 and 0.68, respectively, and for the 2Dâ+â3D set 0.62 and 0.65, respectively. Inter-rater agreement (Reader 1 vs. Reader 2) on EPE using Cohen's kappa for the 2D and 2Dâ+â3D set, respectively, was 0.42 and 0.17 (i.e. moderate and poor agreement, respectively). CONCLUSION: The addition of 3D T2W MRI with radial reconstructions did not improve local staging in prostate cancer
The Scandinavian Sarcoma Group Central Register : 6,000 patients after 25 years of monitoring of referral and treatment of extremity and trunk wall soft-tissue sarcoma
Purpose - We wanted to examine the potential of the Scandinavian Sarcoma Group (SSG) Central Register, and evaluate referral and treatment practice for soft-tissue sarcomas in the extremities and trunk wall (STS) in the Nordic countries. Background - Based on incidence rates from the literature, 8,150 (7,000-9,300) cases of STS of the extremity and trunk wall should have been diagnosed in Norway, Finland, Iceland, and Sweden from 1987 through 2011. The SSG Register has 6,027 cases registered from this period, with 5,837 having complete registration of key variables. 10 centers have been reporting to the Register. The 5 centers that consistently report treat approximately 90% of the cases in their respective regions. The remaining centers have reported all the patients who were treated during certain time periods, but not for the entire 25-year period. Results - 59% of patients were referred to a sarcoma center untouched, i.e. before any attempt at open biopsy. There was an improvement from 52% during the first 5 years to 70% during the last 5 years. 50% had wide or better margins at surgery. Wide margins are now achieved less often than 20 years ago, in parallel with an increase in the use of radiotherapy. For the centers that consistently report, 97% of surviving patients are followed for more than 4 years. Metastasis-free survival (MFS) increased from 67% to 73% during the 25-year period. Interpretation - The Register is considered to be representative of extremity and trunk wall sarcoma disease in the population of Scandinavia, treated at the reporting centers. There were no clinically significant differences in treatment results at these centers.Peer reviewe
Expression of the Arabidopsis thaliana immune receptor EFR in Medicago truncatula reduces infection by a root pathogenic bacterium, but not nitrogenâfixing rhizobial symbiosis
Interfamily transfer of plant pattern recognition receptors (PRRs) represents a promising biotechnological approach to engineer broadâspectrum, and potentially durable, disease resistance in crops. It is however unclear whether new recognition specificities to given pathogenâassociated molecular patterns (PAMPs) affect the interaction of the recipient plant with beneficial microbes. To test this in a direct reductionist approach, we transferred the Brassicaceaeâspecific PRR ELONGATION FACTORâTHERMO UNSTABLE RECEPTOR (EFR), conferring recognition of the bacterial EFâTu protein, from Arabidopsis thaliana to the legume Medicago truncatula. Constitutive EFR expression led to EFR accumulation and activation of immune responses upon treatment with the EFâTuâderived elf18 peptide in leaves and roots. The interaction of M. truncatula with the bacterial symbiont Sinorhizobium meliloti is characterized by the formation of root nodules that fix atmospheric nitrogen. Although nodule numbers were slightly reduced at an early stage of the infection in EFRâMedicago when compared to control lines, nodulation was similar in all lines at later stages. Furthermore, nodule colonization by rhizobia, and nitrogen fixation were not compromised by EFR expression. Importantly, the M. truncatula lines expressing EFR were substantially more resistant to the root bacterial pathogen Ralstonia solanacearum. Our data suggest that the transfer of EFR to M. truncatula does not impede root nodule symbiosis, but has a positive impact on disease resistance against a bacterial pathogen. In addition, our results indicate that Rhizobium can either avoid PAMP recognition during the infection process, or is able to actively suppress immune signaling
Measurement of global polarization of {\Lambda} hyperons in few-GeV heavy-ion collisions
The global polarization of {\Lambda} hyperons along the total orbital angular
momentum of a relativistic heavy-ion collision is presented based on the high
statistics data samples collected in Au+Au collisions at \sqrt{s_{NN}} = 2.4
GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer
(HADES) at GSI, Darmstadt. This is the first measurement below the strangeness
production threshold in nucleon-nucleon collisions. Results are reported as a
function of the collision centrality as well as a function of the hyperon
transverse momentum (p_T) and rapidity (y_{CM}) for the range of centrality
0--40%. We observe a strong centrality dependence of the polarization with an
increasing signal towards peripheral collisions. For mid-central (20--40%)
collisions the polarization magnitudes are (%) = 6.0 \pm 1.3
(stat.) \pm 2.0 (syst.) for Au+Au and (%) = 4.6 \pm 0.4 (stat.)
\pm 0.5 (syst.) for Ag+Ag, which are the largest values observed so far. This
observation thus provides a continuation of the increasing trend previously
observed by STAR and contrasts expectations from recent theoretical
calculations predicting a maximum in the region of collision energies about 3
GeV. The observed polarization is of a similar magnitude as predicted by 3D
fluid dynamics and the UrQMD plus thermal vorticity model and significantly
above results from the AMPT model.Comment: 8 pages, 4 figure
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