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1,517 result(s) for "ADAPT"
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Biophysical Investigations Elucidating the Mechanisms of Action of Antimicrobial Peptides and Their Synergism
Biophysical and structural investigations are presented with a focus on the membrane lipid interactions of cationic linear antibiotic peptides such as magainin, PGLa, LL37, and melittin. Observations made with these peptides are distinct as seen from data obtained with the hydrophobic peptide alamethicin. The cationic amphipathic peptides predominantly adopt membrane alignments parallel to the bilayer surface; thus the distribution of polar and non-polar side chains of the amphipathic helices mirror the environmental changes at the membrane interface. Such a membrane partitioning of an amphipathic helix has been shown to cause considerable disruptions in the lipid packing arrangements, transient openings at low peptide concentration, and membrane disintegration at higher peptide-to-lipid ratios. The manifold supramolecular arrangements adopted by lipids and peptides are represented by the ‘soft membranes adapt and respond, also transiently’ (SMART) model. Whereas molecular dynamics simulations provide atomistic views on lipid membranes in the presence of antimicrobial peptides, the biophysical investigations reveal interesting details on a molecular and supramolecular level, and recent microscopic imaging experiments delineate interesting sequences of events when bacterial cells are exposed to such peptides. Finally, biophysical studies that aim to reveal the mechanisms of synergistic interactions of magainin 2 and PGLa are presented, including unpublished isothermal titration calorimetry (ITC), circular dichroism (CD) and dynamic light scattering (DLS) measurements that suggest that the peptides are involved in liposome agglutination by mediating intermembrane interactions. A number of structural events are presented in schematic models that relate to the antimicrobial and synergistic mechanism of amphipathic peptides when they are aligned parallel to the membrane surface.
Career Adaptability, Self‐Esteem, and Social Support Among Hong Kong University Students
Career adaptability manifests itself through 4 self‐regulated internal resources for coping with occupational challenges and transitions: concern, control, curiosity, and confidence. Few studies have examined career adaptability specifically in the Hong Kong context. The Career Adapt‐Abilities Scale–China Form (CAAS‐China; Hou, Leung, Li, Li, & Xu, 2012) was administered, along with measures of self‐esteem and social support, to 522 Hong Kong Chinese undergraduate students. Results indicated that the CAAS‐China is a reliable and valid instrument for use with these students. Data also showed that self‐esteem was strongly associated with career adaptability, and this relationship was partially mediated by perceived social support. Implications for careers counseling in universities and colleges are discussed.
Analysis of online plan adaptation for 1.5T magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) of prostate cancer
Purpose To analyze and characterize the online plan adaptation of 1.5T magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) of prostate cancer (PC). Methods PC patients ( n  = 107) who received adaptive 1.5 Tesla MRgSBRT were included. Online plan adaptation was implemented by either the adapt-to-position (ATP) or adapt-to-shape (ATS) methods. Patients were assigned to the ATS group if they underwent ≥ 1 ATS fraction ( n  = 51); the remainder were assigned to the ATP group ( n  = 56). The online plan adaptation records of 535 (107 × 5) fractions were retrospectively reviewed. Rationales for ATS decision-making were determined and analyzed using predefined criteria. Statistics of ATS fractions were summarized. Associations of patient characteristics and clinical factors with ATS utilization were investigated. Results There were 87 (16.3%) ATS fractions and 448 ATP fractions (83.7%). The numbers of ATS adoptions in fractions 1–5 were 29 (29/107, 27.1%), 18 (16.8%), 15 (14.0%), 16 (15.0%), and 9 (8.4%), respectively, with significant differences in adoption frequency between fractions ( p  = 0.007). Other baseline patient characteristics and clinical factors were not significantly associated with ATS classification (all p  > 0.05). Underlying criteria for the determination of ATS implementation comprised anatomical changes (77 fractions in 50 patients) and discrete multiple targets (15 fractions in 3 patients). No ATS utilization was determined using dosimetric or online quality assurance criteria. Conclusions This study contributes to facilitating the establishment of a standardized protocol for online MR-guided adaptive radiotherapy in PC.
Online Adaptive MRI-Guided Stereotactic Body Radiotherapy for Pancreatic and Other Intra-Abdominal Cancers
A 1.5T MRI combined with a linear accelerator (Unity®, Elekta; Stockholm, Sweden) is a device that shows promise in MRI-guided stereotactic body radiation treatment (SBRT). Previous studies utilized the manufacturer’s pre-set MRI sequences (i.e., T2 Weighted (T2W)), which limited the visualization of pancreatic and intra-abdominal tumors and organs at risk (OAR). Here, a T1 Weighted (T1W) sequence was utilized to improve the visualization of tumors and OAR for online adapted-to-position (ATP) and adapted-to-shape (ATS) during MRI-guided SBRT. Twenty-six patients, 19 with pancreatic and 7 with intra-abdominal cancers, underwent CT and MRI simulations for SBRT planning before being treated with multi-fractionated MRI-guided SBRT. The boundary of tumors and OAR was more clearly seen on T1W image sets, resulting in fast and accurate contouring during online ATP/ATS planning. Plan quality in 26 patients was dependent on OAR proximity to the target tumor and achieved 96 ± 5% and 92 ± 9% in gross tumor volume D90% and planning target volume D90%. We utilized T1W imaging (about 120 s) to shorten imaging time by 67% compared to T2W imaging (about 360 s) and improve tumor visualization, minimizing target/OAR delineation uncertainty and the treatment margin for sparing OAR. The average time-consumption of MRI-guided SBRT for the first 21 patients was 55 ± 15 min for ATP and 79 ± 20 min for ATS.
Dynamic NO x emission prediction based on composite models adapt to different operating conditions of coal-fired utility boilers
An accurate NO concentration prediction model plays an important role in low NO emission control in power stations. Predicting NO in advance is of great significance in satisfying stringent environmental policies. This study aims to accurately predict the NO emission concentration at the outlet of boilers on different operating conditions to support the DeNO procedure. Through mutual information analysis, suitable features are selected to build models. Long short-term memory (LSTM) models are utilized to predict NO concentration at the boiler's outlet from selected input features and exhibit power in fitting multivariable coupling, nonlinear, and large time-delay systems. Moreover, a composite LSTM model composed of models on different operating conditions, like steady-state and transient-state condition, is prosed. Results of one whole day of typical operating data show that the accuracy of the NO concentration and fluctuation trend prediction based on this composite model is superior to that using a single LSTM model and other non-time-sequence models. The root mean square error (RMSE) and R of the composite LSTM model are 3.53 mg/m and 0.89, respectively, which are better than those of a single LSTM (i.e., 5.50 mg/m and 0.78, respectively).
Risk analysis of the Unity 1.5T MR‐Linac adapt‐to‐shape workflow
Background and Purpose The adapt‐to‐shape (ATS) workflow on the Unity MR‐Linac (Elekta AB, Stockholm, Sweden) allows for full replanning including recontouring and reoptimization5. Additional complexity to this workflow is added when the adaptation involves the use of MIM Maestro (MIM Software, Cleveland, OH) software in conjunction with Monaco (Elekta AB, Stockholm, Sweden). Given the interplay of various systems and the inherent complexity of the ATS workflow, a risk analysis would be instructive. Method Failure modes and effects analysis (FMEA) following Task Group 10013 was completed to evaluate the ATS workflow. A multi‐disciplinary team was formed for this analysis. The team created a process map detailing the steps involved in ATS treating both the standard Monaco workflow and a workflow with the use of MIM software in parallel. From this, failure modes were identified, scored using three categories (likelihood of occurrence, severity, and detectability which multiplied create a risk priority number), and then mitigations for the top 20th percentile of failure modes were found. Results Risk analysis found 264 failure modes in the ATS workflow. Of those, 82 were high‐ranking failure modes that ranked in the top 20th percentile for risk priority number and severity scores. Although high‐ranking failure modes were identified in each step in the process, 62 of them were found in the contouring and planning steps, highlighting key differences from adapt‐to‐position (ATP), where the importance of these steps are minimized. Mitigations are suggested for all high‐ranking failure modes. Conclusion The flexibility of the ATS workflow, which enables reoptimization of the treatment plan, also introduces potential critical points where errors can occur. There are more opportunities for error in ATS that can create unintentionally negative dosimetric impact. FMEA can help mitigate these risks by identifying and addressing potential failure points in the ATS process.
A direct aspiration first-pass technique (ADAPT) versus stent retriever for acute ischemic stroke (AIS): a systematic review and meta-analysis
Background and purposeThere is an ongoing debate about whether a direct aspiration first-pass technique (ADAPT) or stent retriever should be used as the first-pass mechanical thrombectomy device for patients with acute ischemic stroke (AIS). This meta-analysis aimed to compare the safety and efficacy of ADAPT versus stent retriever in patients with AIS.MethodsStructured searches on the PubMed, Embase, and Cochrane Library databases were conducted through July 2020. The primary outcomes of this study were: successful and complete recanalization; excellent and favorable outcomes; all-cause mortality at 90 days; and symptomatic intracerebral hemorrhage (sICH). The secondary outcomes of this study were: successful recanalization by primary chosen device; additional therapy; occurrence of emboli in a new territory; hemorrhagic complication; hemorrhagic infarction; parenchymatous hematoma; and subarachnoid hemorrhage. The odds ratios (ORs) with 95% confidence intervals (CIs) of the primary and secondary outcomes were calculated using a random-effects model. I2 statistics were used to assess the heterogeneity for each outcome among the included studies.ResultsFinally, 20 studies with a total of 6311 patients were included in our meta-analysis. There were no significant differences between the ADAPT group and the stent retriever group of the primary and secondary outcomes except additional therapy. Our pooled results indicated that patients in the ADAPT group needed more additional therapy than those in the stent retriever group (OR 2.24, 95% CI 1.41–3.57).ConclusionIn conclusion, our meta-analysis showed similar clinical outcomes of ADAPT and stent retriever. However, patients in the ADAPT group had higher additional therapy rates than those in the stent retriever group. Due to several inevitable limitations of this meta-analysis, more large-scale randomized controlled trials are required to further investigate this topic.
Tuning a secondary dose verification software for a CT‐guided online adaptive delivery system
Background Quality assurance (QA) remains unstandardized for CT‐guided online adaptive radiotherapy (CTgART) platforms (Ethos, Varian Medical Systems, Inc., Palo Alto, CA), as they become more clinically prevalent. A secondary dose calculation software (Mobius3D, Varian Medical Systems, Inc., Palo Alto, CA) is provided for this closed CTgART system. However, the clinical impact of tuning dosimetric leaf gap (DLG) correction values for specific delivery techniques for CTgART secondary dose calculations remains uninvestigated. Purpose Tuning the DLG correction value for different delivery techniques of the independent secondary dose verification software for adaptive online QA. Methods A total of 31 volumetric arc therapy (VMAT) and 13 fixed‐gantry intensity modulated radiation therapy (IMRT) plans were selected from representative anatomical sites treated in our clinic. All plans were evaluated on a patient CT dataset and a QA dataset of a solid water phantom with an embedded ion chamber placed at the center in both primary treatment planning systems (TPS) and secondary dose verification software. Primary TPS plan doses were compared with secondary calculation doses on patient CT by calculating 3D gamma passing criteria under different DLG correction values ranging from –2 to 2 mm to determine the optimal DLG correction range. Ion chamber verification measurements were then compared to secondary calculation dose to determine the optimal DLG correction value by minimizing the difference for IMRT and VMAT plans, separately. Results The optimal DLG correction values for VMAT and IMRT techniques were –0.3 and 0.4 mm respectively for the selected clinical cohort of patients. The mean gamma passing rate between primary and secondary doses for VMAT and IMRT were 99.0% ± 1.0% and 99.9% ± 0.1% with 3%/2 mm and excluding 10% low dose criteria. The mean ion chamber agreement for VMAT and IMRT were 0.0% ± 2.1% and 0.2% ± 1.4%. Conclusion DLG correction value should be tuned for each delivery technique (VMAT and IMRT) separately to maximize the robustness of CTgART online QA programs.
Healthcare Access and Quality Index based on mortality from causes amenable to personal health care in 195 countries and territories, 1990–2015: a novel analysis from the Global Burden of Disease Study 2015
National levels of personal health-care access and quality can be approximated by measuring mortality rates from causes that should not be fatal in the presence of effective medical care (ie, amenable mortality). Previous analyses of mortality amenable to health care only focused on high-income countries and faced several methodological challenges. In the present analysis, we use the highly standardised cause of death and risk factor estimates generated through the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) to improve and expand the quantification of personal health-care access and quality for 195 countries and territories from 1990 to 2015. We mapped the most widely used list of causes amenable to personal health care developed by Nolte and McKee to 32 GBD causes. We accounted for variations in cause of death certification and misclassifications through the extensive data standardisation processes and redistribution algorithms developed for GBD. To isolate the effects of personal health-care access and quality, we risk-standardised cause-specific mortality rates for each geography-year by removing the joint effects of local environmental and behavioural risks, and adding back the global levels of risk exposure as estimated for GBD 2015. We employed principal component analysis to create a single, interpretable summary measure–the Healthcare Quality and Access (HAQ) Index–on a scale of 0 to 100. The HAQ Index showed strong convergence validity as compared with other health-system indicators, including health expenditure per capita (r=0·88), an index of 11 universal health coverage interventions (r=0·83), and human resources for health per 1000 (r=0·77). We used free disposal hull analysis with bootstrapping to produce a frontier based on the relationship between the HAQ Index and the Socio-demographic Index (SDI), a measure of overall development consisting of income per capita, average years of education, and total fertility rates. This frontier allowed us to better quantify the maximum levels of personal health-care access and quality achieved across the development spectrum, and pinpoint geographies where gaps between observed and potential levels have narrowed or widened over time. Between 1990 and 2015, nearly all countries and territories saw their HAQ Index values improve; nonetheless, the difference between the highest and lowest observed HAQ Index was larger in 2015 than in 1990, ranging from 28·6 to 94·6. Of 195 geographies, 167 had statistically significant increases in HAQ Index levels since 1990, with South Korea, Turkey, Peru, China, and the Maldives recording among the largest gains by 2015. Performance on the HAQ Index and individual causes showed distinct patterns by region and level of development, yet substantial heterogeneities emerged for several causes, including cancers in highest-SDI countries; chronic kidney disease, diabetes, diarrhoeal diseases, and lower respiratory infections among middle-SDI countries; and measles and tetanus among lowest-SDI countries. While the global HAQ Index average rose from 40·7 (95% uncertainty interval, 39·0–42·8) in 1990 to 53·7 (52·2–55·4) in 2015, far less progress occurred in narrowing the gap between observed HAQ Index values and maximum levels achieved; at the global level, the difference between the observed and frontier HAQ Index only decreased from 21·2 in 1990 to 20·1 in 2015. If every country and territory had achieved the highest observed HAQ Index by their corresponding level of SDI, the global average would have been 73·8 in 2015. Several countries, particularly in eastern and western sub-Saharan Africa, reached HAQ Index values similar to or beyond their development levels, whereas others, namely in southern sub-Saharan Africa, the Middle East, and south Asia, lagged behind what geographies of similar development attained between 1990 and 2015. This novel extension of the GBD Study shows the untapped potential for personal health-care access and quality improvement across the development spectrum. Amid substantive advances in personal health care at the national level, heterogeneous patterns for individual causes in given countries or territories suggest that few places have consistently achieved optimal health-care access and quality across health-system functions and therapeutic areas. This is especially evident in middle-SDI countries, many of which have recently undergone or are currently experiencing epidemiological transitions. The HAQ Index, if paired with other measures of health-system characteristics such as intervention coverage, could provide a robust avenue for tracking progress on universal health coverage and identifying local priorities for strengthening personal health-care quality and access throughout the world. Bill & Melinda Gates Foundation.
Toward more flood resilience
European countries face increasing flood risks because of urbanization, increase of exposure and damage potential, and the effects of climate change. In literature and in practice, it is argued that a diversification of strategies for flood risk management (FRM), including flood risk prevention (through proactive spatial planning), flood defense, flood risk mitigation, flood preparation, and flood recovery, makes countries more flood resilient. Although this thesis is plausible, it should still be empirically scrutinized. We aim to do this. Drawing on existing literature we operationalize the notion of “flood resilience” into three capacities: capacity to resist; capacity to absorb and recover; and capacity to transform and adapt. Based on findings from the EU FP7 project STAR-FLOOD, we explore the degree of diversification of FRM strategies and related flood risk governance arrangements at the national level in Belgium, England, France, the Netherlands, Poland, and Sweden, as well as these countries’ achievement in terms of the three capacities. We found that the Netherlands and to a lesser extent Belgium have a strong capacity to resist, France a strong capacity to absorb and recover, and especially England a high capacity to transform and adapt. Having a diverse portfolio of FRM strategies in place may be conducive to high achievements related to the capacities to absorb/recover and to transform and adapt. Hence, we conclude that diversification of FRM strategies contributes to resilience. However, the diversification thesis should be nuanced in the sense that there are different ways to be resilient. First, the three capacities imply different rationales and normative starting points for flood risk governance, the choice between which is inherently political. Second, we found trade-offs between the three capacities, e.g., being resistant seems to lower the possibility to be absorbent. Third, to explain countries’ achievements in terms of resilience, the strategies’ feasibility in specific physical circumstances and their fit in existing institutional contexts (appropriateness), as well as the establishment of links between strategies, through bridging mechanisms, have also been shown to be crucial factors. We provide much needed reflection on the implications of this diagnosis for governments, private parties, and citizens who want to increase flood resilience.