109 research outputs found
CTP regulates membrane-binding activity of the nucleoid occlusion protein Noc
No full text\ua9 2021 The Author(s). ATP- and GTP-dependent molecular switches are extensively used to control functions of proteins in a wide range of biological processes. However, CTP switches are rarely reported. Here, we report that a nucleoid occlusion protein Noc is a CTPase enzyme whose membrane-binding activity is directly regulated by a CTP switch. In Bacillus subtilis, Noc nucleates on 16 bp NBS sites before associating with neighboring non-specific DNA to form large membrane-associated nucleoprotein complexes to physically occlude assembly of the cell division machinery. By in vitro reconstitution, we show that (1) CTP is required for Noc to form the NBS-dependent nucleoprotein complex, and (2) CTP binding, but not hydrolysis, switches Noc to a membrane-active state. Overall, we suggest that CTP couples membrane-binding activity of Noc to nucleoprotein complex formation to ensure productive recruitment of DNA to the bacterial cell membrane for nucleoid occlusion activity
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No full textCTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable
Colluding Tags Attack on the ECC-based Grouping Proofs for Rfids
No full textRecently, a new privacy-preserving elliptic curve based grouping proof protocol with colluding tag prevention( CTP) has been proposed. The CTP protocol is claimed to be resistant against colluding tags attacks in which the involved tags can exchange some messages via another reader before the protocol starts without revealing their private keys. In this paper, we show that the CTP protocol is vulnerable to some colluding tag attacking scenario. In addition, we propose a new elliptic curve based grouping protocol which can fix the problem. Our proposal is based on a formally proved privacy preserving authentication protocol and has the advantage of being resistant against colluding tags attacks with the same amount of computation
Quantification of myocardial blood flow using dynamic 320-row multi-detector CT as compared with O-15-H2O PET
No full textThis study introduces a method to calculate myocardium blood flow (MBF) and coronary flow reserve (CFR) using the relatively low-dose dynamic 320-row multi-detector computed tomography (MDCT), validates the method against O-15-H2O positron-emission tomography (PET) and assesses the CFRs of coronary artery disease (CAD) patients. Thirty-two subjects underwent both dynamic CT perfusion (CTP) and PET perfusion imaging at rest and during pharmacological stress. In 12 normal subjects (pilot group), the calculation method for MBF and CFR was established. In the other 13 normal subjects (validation group), MBF and CFR obtained by dynamic CTP and PET were compared. Finally, the CFRs obtained by dynamic CTP and PET were compared between the validation group and CAD patients (n = 7). Correlation between MBF of MDCT and PET was strong (r = 0.95, P < 0.0001). CFR showed good correlation between dynamic CTP and PET (r = 0.67, P = 0.0126). CFRCT in the CAD group (2.3 +/- 0.8) was significantly lower than that in the validation group (5.2 +/- 1.8) (P = 0.0011). We established a method for measuring MBF and CFR with the relatively low-dose dynamic MDCT. Lower CFR was well demonstrated in CAD patients by dynamic CTP. aEuro cent MBF and CFR can be calculated using dynamic CTP with 320-row MDCT. aEuro cent MBF and CFR showed good correlation between dynamic CTP and PET. aEuro cent Lower CFR was well demonstrated in CAD patients by dynamic CTP
Network Lifetime Analysis of Data Collection Protocols
No full textWhen a sensor network is deployed, we fundamentally care about three main outcomes: to obtain as much data as possible (high delivery rate), to obtain data as fast as possible (low latency), and to obtain data for as long as possible (long lifetime). This last metric, called network lifetime, is of great importance and has been widely investigated because sensor nodes are usually battery-operated. However, there is a gap between the many theoretical studies and the very few empirical ones. The aim of this thesis is to bridge that gap. To achieve our aim, we analyze two well-known data collection protocols: one based on shortest-path trees, called CTP; and the other based on opportunistic routing, called ORW. Both protocols have advantages and disadvantages with respect to the network lifetime. On the one hand, CTP reduces the total number of ransmissions in the network, but uses an expensive communication primitive and does not care about load balancing. On the other hand, ORW has the exact opposite characteristics, good load balancing with an efficient communication primitive at the cost of increasing the total number of transmissions. There is hence an open question to solve: which protocol provides longer lifetimes? We tackle the problem from an analytical and a practical erspective. For the analytical part, we improve the accuracy of current energy models for CTP and develop a new energy model for ORW. Our models for CTP are up to 95% more accurate than the state-of-the-art. For the empirical part, we evaluate both protocols on a public testbed with 100 nodes. Our analytical results show that ORW has longer lifetimes than CTP for high density networks, and that this advantage should vanish in low density networks. Our empirical results validate that ORW is indeed better than CTP under high densities, but for lower densities, our experiments actually show that ORW performs significantly worse than CTP. We show that this unexpected behaviour (according to the model) is due to some inherent flaws in the implementation of ORW.Embedded SystemMicroelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
Time dependency of automated collateral scores in computed tomography angiography and computed tomography perfusion images in patients with intracranial arterial occlusion
No full textPurpose: The assessment of collateral status may depend on the timing of image acquisition. The purpose of this study is to investigate whether there are optimal time points in CT Perfusion (CTP) for collateral status assessment, and compare collaterals scores at these time points with collateral scores from multiphase CT angiography (mCTA). Methods: Patients with an acute intracranial occlusion who underwent baseline non-contrast CT, mCTA and CT perfusion were selected. Collateral status was assessed using an automatically computed Collateral Ratio (CR) score in mCTA, and predefined time points in CTP acquisition. CRs extracted from CTP were correlated with CRs from mCTA. In addition, all CRs were related to baseline National Institutes of Health Stroke Scale (NIHSS) and Alberta Stoke Program Early CT Score (ASPECTS) with linear regression analysis to find the optimal CR. Results: In total 58 subjects (median age 74 years; interquartile range 61–83 years; 33 male) were included. When comparing the CRs from the CTP vs. mCTA acquisition, the strongest correlations were found between CR from baseline mCTA and the CR at the maximal intensity projection of time-resolved CTP (r = 0.81) and the CR at the peak of arterial enhancement point (r = 0.78). Baseline mCTA-derived CR had the highest correlation with ASPECTS (β = 0.36 (95%CI 0.11, 0.61)) and NIHSS (β = − 0.48 (95%CI − 0.72, − 0.16)). Conclusion: Collateral status assessment strongly depends on the timing of acquisition. Collateral scores obtained from mCTA imaging is close to the optimal collateral score obtained from CTP imaging.ImPhys/Medical ImagingImPhys/Computational Imagin
[[alternative]]The Experimental Study of Application of Critical Thinking in Senior High School Music Appreciation Instruction
No full text[[abstract]]The purposes of this study were to develop a critical thinking program(CTP) based on the theoretical framework and teaching model of music appreciation. The study methods were employed including literature review, experiments and interviews, to comprehended CTP’s feasibility in the school music curriculum, and by undergoing a 5-week teaching experiment to evaluate the effects of appreciation instruction on comprehensive school students. The subjects of this study were totally 96 students of 10th grades in senior industrial vocational school National Changhua University of Education. Among them, 48 were grouped as the experiment group and 46 as the control group.
After CTP instruction, the major results indicated:
1. CTP could improve 10th grade students’ holistic ability of music appreciation.
2. The students in the experiment team had a positive assessment toward the experiment.
Great improvement could be found in the design of CTP and students’ reaction by using CTP instruction.
The interviews were confirmed the students’ positive assessment again, and found preparing together with reviewing could enhance the interesting and effectiveness of music learning. Besides, there were other suggestions as follow: First, to play more times of music pieces; second, to base on the foundation of solo music while listening music in concert; third, to prolong and add discuss time both in groups and at worksheet, and the last as to establish students’ music aesthetic value before CTP instruction.
The suggestions based on the process and results of this study in the hope to serve as references for future improvement and research on education were proposed.
Computed tomography angiography-based deep learning method for treatment selection and infarct volume prediction in anterior cerebral circulation large vessel occlusion
No full textBackground: Computed tomography perfusion (CTP) is the mainstay to determine possible eligibility for endovascular thrombectomy (EVT), but there is still a need for alternative methods in patient triage. Purpose: To study the ability of a computed tomography angiography (CTA)-based convolutional neural network (CNN) method in predicting final infarct volume in patients with large vessel occlusion successfully treated with endovascular therapy. Materials and Methods: The accuracy of the CTA source image-based CNN in final infarct volume prediction was evaluated against follow-up CT or MR imaging in 89 patients with anterior circulation ischemic stroke successfully treated with EVT as defined by Thrombolysis in Cerebral Infarction category 2b or 3 using Pearson correlation coefficients and intraclass correlation coefficients. Convolutional neural network performance was also compared to a commercially available CTP-based software (RAPID, iSchemaView). Results: A correlation with final infarct volumes was found for both CNN and CTP-RAPID in patients presenting 6-24 h from symptom onset or last known well, with r = 0.67 (p < 0.001) and r = 0.82 (p < 0.001), respectively. Correlations with final infarct volumes in the early time window (0-6 h) were r = 0.43 (p = 0.002) for the CNN and r = 0.58 (p < 0.001) for CTP-RAPID. Compared to CTP-RAPID predictions, CNN estimated eligibility for thrombectomy according to ischemic core size in the late time window with a sensitivity of 0.38 and specificity of 0.89. Conclusion: A CTA-based CNN method had moderate correlation with final infarct volumes in the late time window in patients successfully treated with EVT.Peer reviewe
Appropriate Use of CT Perfusion following Aneurysmal Subarachnoid Hemorrhage: A Bayesian Analysis Approach
No full textThese investigators evaluated the test characteristics of CTP in patients with SAH for detection of delayed cerebral ischemia. Ninety-seven patients were assessed with CTP for ischemia and with DSA for vasospasm. The authors concluded that positive CTP findings identified patients who should be carefully considered for induced hypertension, hypervolemia, and hemodilution and/or intra-arterial therapy while negative CTP findings are useful in guiding a no-treatment decision. BACKGROUND AND PURPOSE: In recent years CTP has been used as a complementary diagnostic tool in the evaluation of delayed cerebral ischemia and vasospasm. Our aim was to determine the test characteristics of CTP for detecting delayed cerebral ischemia and vasospasm in SAH, and then to apply Bayesian analysis to identify subgroups for its appropriate use. MATERIALS AND METHODS: Our retrospective cohort comprised consecutive patients with SAH and CTP performed between days 6 and 8 following aneurysm rupture. Delayed cerebral ischemia was determined according to primary outcome measures of infarction and/or permanent neurologic deficits. Vasospasm was determined by using DSA. The test characteristics of CTP and its 95% CIs were calculated. Graphs of conditional probabilities were constructed by using Bayesian techniques. Local treatment thresholds (posttest probability of delayed cerebral ischemia needed to initiate induced hypertension, hypervolemia, and hemodilution or intra-arterial therapy) were determined via a survey of 6 independent neurologists. RESULTS: Ninety-seven patients with SAH were included in the study; 39% (38/97) developed delayed cerebral ischemia. Qualitative CTP deficits were seen in 49% (48/97), occurring in 84% (32/38) with delayed cerebral ischemia and 27% (16/59) without. The sensitivity, specificity, and positive and negative predictive values (95% CI) for CTP were 0.84 (0.73-0.96), 0.73 (0.62-0.84), 0.67 (0.51-0.79), and 0.88 (0.74-0.94), respectively. A subgroup of 57 patients underwent DSA; 63% (36/57) developed vasospasm. Qualitative CTP deficits were seen in 70% (40/57), occurring in 97% (35/36) with vasospasm and 23% (5/21) without. The sensitivity, specificity, and positive and negative predictive values (95% CI) for CTP were 0.97 (0.92-1.0), 0.76 (0.58-0.94), 0.88 (0.72-0.95), and 0.94 (0.69-0.99), respectively. Treatment thresholds were determined as 30% for induced hypertension, hypervolemia, and hemodilution and 70% for intra-arterial therapy. CONCLUSIONS: Positive CTP findings identify patients who should be carefully considered for induced hypertension, hypervolemia, and hemodilution and/or intra-arterial therapy while negative CTP findings are useful in guiding a no-treatment decision
Practical issues relating to the taxation of Real Estate Investment Trusts ("REITs") in South Africa.
No full textIncludes bibliographical references.In this dissertation, the author focuses on the practical tax issues relating to the recently adopted South African Real Estate Investment Trust tax dispensation, by discussing international principles of Real Estate Investment Trust taxation and two foreign regimes, i.e. the US and UK Real Estate Investment Trust regimes which, it is understood, were used as a basis for the South African legislation. In addition, the dissertation discusses the details of the South African property investment vehicles regime pre- 1 April 2013, and the new Real Estate Investment Trust tax regime applicable from 1 April 2013. Furthermore, it looks at suggestions and possible improvement to the taxation of Real Estate Investment Trusts in South Africa and whether the proposed amendments released by National Treasury, on 4 July 2013, satisfactorily address the issues raised in this dissertation
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