967 research outputs found
The Minimum Shared Edges Problem on Grid-like Graphs
We study the NP-hard Minimum Shared Edges (MSE) problem on graphs: decide
whether it is possible to route paths from a start vertex to a target
vertex in a given graph while using at most edges more than once. We show
that MSE can be decided on bounded (i.e. finite) grids in linear time when both
dimensions are either small or large compared to the number of paths. On
the contrary, we show that MSE remains NP-hard on subgraphs of bounded grids.
Finally, we study MSE from a parametrised complexity point of view. It is known
that MSE is fixed-parameter tractable with respect to the number of paths.
We show that, under standard complexity-theoretical assumptions, the problem
parametrised by the combined parameter , , maximum degree, diameter, and
treewidth does not admit a polynomial-size problem kernel, even when restricted
to planar graphs
A study of the time of hospital discharge of differentiated thyroid cancer patients after receiving iodine-131 for thyroid remnant ablation treatment
The aim of this study was to measure the radiation exposure rate from differentiated thyroid carcinoma (DTC) patients who had received iodine-131 (131I) treatment, and to evaluate hospital discharge planning in relation to three different sets of regulations. We studied 100 patients, 78 females and 22 males, aged 13 to 79 years (mean 44.40±15.83 years) with DTC, in three Groups who were treated with 3.7, 5.5 or 7.4GBq of 131I, respectively. The external whole-body dose rates following oral administration of 131I were measured after each one of the first three hospitalization days. A multivariant linear analysis was performed, considering exposure rates as dependent variables to the administered dose for treatment, age, gender, regional and/or distant metastases, thyroglobulin (Tg), antibodies to Tg and thyroid remnant in the three dose groups. We found that the exposure rates after each of the three first days of hospitalization were 30, 50 and 70μSvh-1 at 1m. All our DTC patients had an acceptable dose rate on days 2 and 3 that allowed their hospital discharge. After only 1 day of hospitalization, just 3/11 cases showed not permissible exposure rates above 70μSvh-1. In conclusion, it is the opinion of the authors that after measuring the exposure rates, most treated, DTC patients could be discharged after only one day of hospitalization, even some of those treated with high doses of 131I (7.4GBq). Patients, who received the higher doses of 131I, should not be released before their individual exposure rate is measured
The utility and prognostic value of dipyridamole technetium-99m sestamibi myocardial perfusion imaging SPECT in predicting perioperative cardiac events following non-cardiac surgery
Objective: A perioperative cardiac events is one of the most important medical concerns for both surgeons and patients. The purpose of the current study was to determine the prognostic value of myocardial perfusion imaging (MPI), using dipyridamole 99m Tc-MIBI, for the prediction of perioperative cardiac events. Materials and methods: This study included 253 patients who were candidates for non-cardiac elective surgery and underwent scanning with dipyridamole 99m Tc-MIBI. Based on normal or abnormal MPI, patients were divided into two groups and all preoperative cardiac events were recorded. Risk factors, including diabetes mellitus, dyslipidemia, hypertension, smoking and age .70 years, were compared between patients with normal and abnormal MPI and, also, in patients with or without cardiac events. Results: There were 197 patients with normal and 56 patients with abnormal MPI. In total, 14 patients had perioperative cardiac events, which included myocardial infarction (MI), hypotension, arrhythmia and death; of the 14 patients with perioperative cardiac events, 12 had abnormal and two had normal MPI. There were statistically meaningful differences between the two groups (p<0.001). Based on these findings, we determined that MPI had a sensitivity of 85.7%, a specificity of 81.6%, an accuracy of 81.8%, a positive predictive value of 21.4 % and a negative predictive value of 98.9%. Conclusion: The incidence of perioperative cardiac events is higher in patients with abnormal MPI. Dipyridamole 99m Tc-MIBI myocardial perfusion imaging can accurately detect the preoperative cardiac risk of patients undergoing major non-cardiac surgery. Based on these findings, the occurrence of perioperative cardiac events in patients with abnormal MPI should be considered, especially in the older age population (age ≥70). © The Author(s) 2013
Brain perfusion imaging with voxel-based analysis in secondary progressive multiple sclerosis patients with a moderate to severe stage of disease: a boon for the workforce
Background: The present study was carried out to evaluate cerebral perfusion in multiple sclerosis (MS) patients
with a moderate to severe stage of disease. Some patients underwent hyperbaric oxygen therapy (HBOT) and brain
perfusion between before and after that was compared.
Methods: We retrospectively reviewed 25 secondary progressive (SP)-MS patients from the hospital database.
Neurological disability evaluated by Expanded Disability Status Scale Score (EDSS). Brain perfusion was performed
by (99 m) Tc-labeled bicisate (ECD) brain SPECT and the data were compared using statistical parametric mapping
(SPM). In total, 16 patients underwent HBOT. Before HBOT and at the end of 20 sessions of oxygen treatment,
99mTc-ECD brain perfusion single photon emission computed tomography (SPECT) was performed again then
the results were evaluated and compared. Brain perfusion was performed by (99 m) Tc-labeled bicisate (ECD) brain
SPECT and the data were compared using statistical parametric mapping (SPM).
Results: A total of 25 SP-MS patients, 14 females (56 %) and 11 males (44 %) with a mean age of 38.92 ± 11.
28 years included in the study. The mean disease duration was 8.70 ± 5.30 years. Of the 25 patients, 2 (8 %) had
a normal SPECT and 23 (92 %) had abnormal brain perfusion SPECT studies. The study showed a significant
association between severity of perfusion impairment with disease duration and also with EDSS (P <0.05). There
was a significant improvement in pre- and post-treatment perfusion scans (P <0.05), but this did not demonstrate
a significant improvement in the clinical subjective and objective evaluation of patients (P >0.05).
Conclusions: This study depicted decreased cerebral perfusion in SP-MS patients with a moderate to severe
disability score and its association with clinical parameters. Because of its accessibility, rather low price, practical
ease, and being objective quantitative information, brain perfusion SPECT can be complementing to other
diagnostic modalities such as MRI and clinical examinations in disease surveillance and monitoring. The literature
on this important issue is extremely scarce, and follow up studies are required to assess these preliminary results
Bonding mechanism from the impact of thermally sprayed solid particles
Power particles are mainly in solid state prior to impact on substrates from high velocity oxy-fuel (HVOF) thermal spraying. The bonding between particles and substrates is critical to ensure the quality of coating. Finite element analysis (FEA) models are developed to simulate the impingement process of solid particle impact on substrates. This numerical study examines the bonding mechanism between particles and substrates and establishes the critical particle impact parameters for bonding. Considering the morphology of particles, the shear-instability–based method is applied to all the particles, and the energy-based method is employed only for spherical particles. The particles are given the properties of widely used WC-Co powder for HVOF thermally sprayed coatings. The numerical results confirm that in the HVOF process, the kinetic energy of the particle prior to impact plays the most dominant role in particle stress localization and melting of the interfacial contact region. The critical impact parameters, such as particle velocity and temperature, are shown to be affected by the shape of particles, while higher impact velocity is required for highly nonspherical powder
C13orf31 (FAMIN) is a central regulator of immunometabolic function.
Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.Supported by the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement 260961, the Wellcome Trust (investigator award 106260/Z/14/Z; a PhD fellowship for clinicians; and a Career Re-Entry Fellowship), the Wellcome Trust Sanger Institute, the US National Institutes of Health (5U420D011174 and 5U54HG006348), the Biotechnology and Biological Sciences Research Council, the National Institute for Health Research Cambridge Biomedical Research Centre, the European Crohn’s and Colitis Organisation and the Swedish Medical Research Council and the Olle Engkvist foundation.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ni.353
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