Incremental Decrease Research Articles

Letter: Neurosurgeons and Curves: The Need for Critical Appraisal of Modeling in the Post-COVID Era

Letter: Neurosurgeons and Curves: The Need for Critical Appraisal of Modeling in the Post-COVID Era

Prediction of Hypoglycemia By Quality of Life Measures: A Retrospective Analysis of Electronically Patient-Reported Data

We aimed to examine the utility of electronically patient-reported data (e-PRD) in exploring the risk of diabetes-related hypoglycemia and to evaluate hypoglycemia prediction by the quality of life (QoL) measures. A retrospective analysis of e-PRD for patients with diabetes mellitus who completed the American Diabetes Association's Low Blood Sugar Questionnaire (Hypo-Q) and the Patient-Reported Outcomes Measurement Information System (PROMIS) for QoL assessment. Associations between Hypo-Q answers and PROMIS scores were described using Spearman correlations and 95% confidence intervals, or medians and quartiles. Records of 538 subjects were reviewed; 55% were female, 95% were non-Hispanic, with a mean age (± SD) of 53 ± 15 years. Patients with type 1 diabetes had a longer disease duration and more hypoglycemic episodes (P<.001) with higher PROMIS Physical and Mental T-scores (P<.001, both), when compared to patients with type 2 diabetes. The latter had a higher number of co-existing conditions. Having >5 episodes of either moderate or severe hypoglycemia in a year were reported by 18% and 5% of all patients, respectively. Mean PROMIS Physical and Mental health T-scores were 46 ± 10 and 47 ± 10, respectively. Patients with fewer moderate and severe hypoglycemic episodes had better Physical (P = .047 and P<.001) and Mental (P = .015 and P<.001) PROMIS T-scores with incremental decreases in the odds of hypoglycemia with each point increase in PROMIS T-scores. e-PRD of QoL measures and Hypo-Q were effective in exposing the risks for hypoglycemia and reproducing published findings with significant associations between QoL measures and hypoglycemia risks while providing new insights.

A novel preoperative risk score to optimize patient selection for performing concomitant liver resection with cytoreductive surgery/HIPEC.

While parenchymal hepatic metastases were previously considered a contraindication to cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC), liver resection (LR) is increasingly performed with CRS/HIPEC. Patients from the US HIPEC Collaborative (2000-2017) with invasive appendiceal or colorectal adenocarcinoma undergoing primary, curative intent CRS/HIPEC with CC0-1 resection were included. LR was defined as a formal parenchymal resection. Primary endpoints were postoperative complications and overall survival (OS). A total of 658 patients were included. About 83 (15%) underwent LR of colorectal (58%) or invasive appendiceal (42%) metastases. LR patients had more complications (81% vs. 60%; p = .001), greater number of complications (2.3 vs. 1.5; p < .001) per patient and required more reoperations (22%vs. 11%; p = .007) and readmissions (39% vs. 25%; p = .014) than non-LR patients. LR patients had decreased OS(2-year OS 62% vs. 79%, p < .001), even when accounting for peritoneal carcinomatosis index and histology type. Preoperative factors associated with decreased OS on multivariable analysis in LR patients included age < 60 years(HR, 3.61; 95% CI, 1.10-11.81), colorectal histology (HR, 3.84; 95% CI, 1.69-12.65), and multiple liver tumors (HR, 3.45; 95% CI, 1.21-9.85) (all p < .05). When assigning one point for each factor, there was an incremental decrease in 2-year survival as the risk score increased from 0 to 3 (0: 100%; 1: 91%; 2: 58%; 3: 0%). As CRS/HIPEC + LR has become more common, we created a simple risk score to stratify patients considered for CRS/HIPEC + LR. These data aid in striking the balance between an increased perioperative complication profile with the potential for improvement in OS.

Success factors in high-effect, low-cost eHealth programs for patients with hypertension: a systematic review and meta-analysis.

eHealth programs can lower blood pressure but also drive healthcare costs. This study aims to review the evidence on the effectiveness and costs of eHealth for hypertension and assess commonalities in programs with high effect and low additional cost. Overall, the incremental decrease in systolic blood pressure using eHealth, compared to usual care, was 3.87 (95% confidence interval (CI) 2.98-4.77) mmHg at 6 months and 5.68 (95% CI 4.77-6.59) mmHg at 12 months' follow-up. High intensity interventions were more effective, resulting in a 2.6 (95% CI 0.5-4.7) (at 6 months) and 3.3 (95% CI 1.4-5.1) (at 12 months) lower systolic blood pressure, but were also more costly, resulting in €170 (95% CI 56-284) higher costs at 6 months and €342 (95% CI 128-556) at 12 months. Programs that included a high volume of participants showed €203 (95% CI 99-307) less costs than those with a low volume at 6 months, and €525 (95% CI 299-751) at 12 months without showing a difference in systolic blood pressure. Studies that implemented eHealth as a partial replacement, rather than addition to usual care, were also less costly (€119 (95% CI -38-201 at 6 months) and €346 (95% CI 261-430 at 12 months)) without being less effective. Evidence on eHealth programs for hypertension is ambiguous, heterogeneity on effectiveness and costs is high (I2 = 56-98%). Effective eHealth with limited additional costs should focus on high intensity interventions, involve a large number of participants and use eHealth as a partial replacement for usual care.

Blood utilization and clinical outcomes in pancreatic surgery before and after implementation of patient blood management.

Over the past decade, patient blood management (PBM) programs have been developed to reduce allogeneic blood utilization. This is particularly important in pancreatic surgery, which has historically been associated with high transfusion requirements and morbid event rates. This study investigated blood utilization and clinical outcomes in pancreatic surgery before, during, and after the implementation of PBM. A total of 3482 pancreatic surgery patients were assessed in a 10-year retrospective cohort study (2009-2019) at a single academic center. Baseline patient characteristics, transfusion practices, postoperative morbidity (infectious, thrombotic, ischemic, respiratory, and renal complications), mortality, and length of stay were compared between patients in the pre-PBM (2009-2013), early-PBM (2014-2016), and mature-PBM (2017-2019) time periods. Multivariable analysis assessed the odds for composite morbidity/mortality. Comparing the mature-PBM to pre-PBM cohorts, transfused units per 100 discharged patients decreased by 53% for erythrocytes (155 to 73; P < .0001), 81% for plasma (79 to 15; P < .038), and 75% for platelets (10 to 2.5; P < .005). Clinical outcomes improved as well, with composite morbid event rates decreasing by more than 50%, from 236 in 1438 patients (16.4%) to 85 in 1145 patients (7.4%) (P < .0001). Mortality and length of stay remained unchanged. Compared to the pre-PBM time period, early-PBM was associated with a risk-adjusted decrease in composite morbidity/mortality (OR 0.73; 95% CI 0.57-0.93; P = .010), while mature-PBM demonstrated a further incremental decrease (OR 0.44; 95% CI 0.33-0.57; P < .0001). The implementation of PBM was associated with substantially decreased blood utilization in pancreatic surgery, without negatively impacting clinical outcomes.

Board monitoring, director connections, and credit quality☆

Firms with poor board monitoring effectiveness receive lower credit ratings and larger credit spreads. I identify these effects by using director deaths as exogenous shocks to monitoring effectiveness. These effects are especially pronounced when firms are highly levered. Incremental decreases in monitoring effectiveness impact credit quality the most when a majority of the board members become co-opted by management and when firms are more likely to increase corporate risk.

Provenance- and life-history stage-specific responses of the dwarf shrub Calluna vulgaris to elevated vapour pressure deficit

Climate change may alter microscale-effective ecosystem properties such as atmospheric water vapour pressure, but consequences for plant growth are insufficiently understood. Within a northwest German heathland an open-top chamber experiment was established to analyse the effects of elevated vapour pressure deficit (eVPD) on growth responses of Calluna vulgaris considering both plant origin (Atlantic (AP), sub-Atlantic (SAP), sub-Continental (SCP)) and life-history stage (1-year vs. 10-year old plants). We hypothesised that the plants’ sensitivity to eVPD decreases (i) from AP to SCP and (ii) with progressing life-history stage. Elevated VPD caused a provenance-specific decrease of shoot increment whilst aboveground biomass productivity remained unaffected. AP and SAP responded with increasing belowground biomass δ13C signatures to eVPD, whereas δ13C values decreased for SCP. Moreover, eVPD increased and decreased belowground biomass δ13C signatures of 1- and 10-year old plants, respectively. These responses to eVPD were related to differences in morphological-chemical traits and the plants’ trait plasticity in response to eVPD. SCP showed the highest aboveground tissue mass density and significantly increased tissue C:N ratios under eVPD. One-year old plants had a tenfold higher shoot:root ratio than 10-year old plants, making young plants more sensitive to eVPD. Our findings demonstrate that the atmospheric water status affects the morphology and physiology of Calluna independent of the soil water status. The results have implications for the conservation of heathlands under climate change: (i) SCP may constitute an appropriate ecotype for assisted migration-approaches, and (ii) management needs to weigh different options for heathland rejuvenation.

Methodology of dynamic factor influence of services on security subsystems that ensure comprehensive security of enterprises

Introduction. In the structure of management of industrial enterprises, it is necessary to create an integrated safety and security system, which has already become traditional and includes sectoral areas (industrial and fi re safety, labor safety, environmental and information security, anti-terrorism security of the facility). The statistics confi rm the facts that the major part of determined hazards is caused by the human factor, including shortcomings (gaps) in the fi eld of impact of personnel of industrial and fi re safety services, labor safety, information security and anti-terrorism security, environmental security (hereinafter – services) on the supervised safety subsystems. To solve this problem, a methodological basis is presented in obtaining indicators of the infl uence (impact) of each of the services, that allows to reveal vulnerabilities in management of considered integrated safety and security system.Methods of research. Approaches using existing methods in integrated safety and security of the enterprises are analyzed, and the features of their application are considered. At the stage of analytical research, it is proposed to apply the method of direct determined factor analysis, which makes it possible to specify the indicators of factor infl uence, divide them into components. At the stage of synthesizing the obtained analytical results, it is offered to apply the method of the objective tree on the basis of inverse calculations allowing to receive coeffi - cients of increment (decrease) of gaps (erroneous actions) of service personnel arising in the dynamic process of their employment relations.Problem statement. The statistical data of fi res at the enterprises of electric power industry of the Russian Federation were processed. The coeffi cients of characteristic infl uence (direct, indirect) were determined. It was necessary to solve the problem with dynamic presentation of service performance indicators (by years) to identify those areas that require the formation of management instructions by the head of the enterprise.Problem solution. The example of inverse problem solution based on the construction of the objective tree, which is characterized by ease of use, visibility, dynamism, universality and uniformity is presented.Conclusion. The results obtained can be integrated as an embedding into an expert or intelligent management system created at the enterprise (for example SAP).

A Comparison of Two Data Sets Used to Measure Expenditure Trends for Local Public Park and Recreation Services

Six studies published between 1978 and 2017 used data from the Census Bureau’s annual publication, Government Finances, to identify trends in local park and recreation expenditures. This paper evaluates the validity of the Government Finances data and conclusions of analyses drawn from it by comparing annual data on park and recreation expenditures collected annually by the Trust for Public Land (TPL) from 2008 through 2017 from the same agencies in the same years published in the U.S. Census Bureau’s Government Finances.Results revealed several key discrepancies between the datasets. First, the Government Finances average total, operating, and capital expenditures for the 100 cities were substantially higher than those reported by TPL. Second, the TPL data showed a gradual and incremental decrease in total expenditures over the decade, whereas the Government Finances data showed a substantial increase in total spending, especially after 2012. Third, the declines in the TPL data in total and operational spending from 2008 to 2009, which marked the onset of the Great Recession were 11.31% and 17.69%, respectively, whereas the Government Finances data showed increases of 1.05% and 5.96%, respectively. Fourth, the Government Finances data showed increases from 2008 to 2016 of 22% in total spending and 6% in operational spending, suggesting park and recreation agencies had fully recovered from the Great Recession, but the TPL data showed declines of 20% and 16% in those expenditures, respectively. Fifth, averages masked substantial variations among cities, as there were dramatic differences in expenditures in the two data sets for many individual municipalities. Our analyses confirmed that concerns relating to the Government Finances dataset were legitimate. Applying those data to monitor trends in expenditures of “mainline” park and recreation agencies is inappropriate and is likely to mislead rather than inform. For the Government Finances data to have utility, the Census Bureau should divide them into “core” and “non-core” services. If that is not done, then we recommend that state associations use the TPL definitions and questionnaire to collect primary information about park and recreation expenditures either annually or biennially to improve monitoring accuracy and inform policy and decision-making. Subscribe to JPRA

The influence of reverse arthroplasty humeral component design features on scapular spine strain

Reverse shoulder arthroplasty (RSA) humeral implant parameters have been previously studied with respect to range of motion, deltoid function, and stability. However, limited literature exists on the influence of humeral design features on scapular spine strain. The purpose of this cadaveric biomechanical simulator study was to evaluate the role of humeral component lateralization and neck-shaft angle (NSA) on scapular spine strain. Eight fresh-frozen cadaveric shoulders were tested using an invitro shoulder simulator. A custom-designed modular RSA system was implanted that allowed for the in situ adjustment of humeral lateralization and NSA. Scapular spine strain was measured by strain gauges placed along the acromion and scapular spine in clinically relevant positions representative of the Levy fracture zones. All testing was conducted in both abduction and forward elevation. In Levy zones 2 and 3, increasing humeral lateralization caused significant incremental decreases in scapular spine strain at 0° and 90° abduction (P < .042). Strain decreases as high as 34% were noted with increases in humeral lateralization from -5 to 15 mm (P = .042). Changing NSA had no statistically significant effect on scapular spine strain (P > .14). Some humeral implant design features in RSA have effects on scapular spine strain. Humeral component lateralization had significant effects, whereas adjusting NSA resulted in no substantial differences in scapular spine strain. Understanding humeral component variables is important to allow for design optimization of future RSA implants.

Exploring the relationship between stand growth, structure and growth dominance in Eucalyptus monoclonal plantations across a continent-wide environmental gradient in Brazil

Stand structure can have a considerable influence on forest growth and productivity. A stand’s response to factors like temperature, precipitation, vapor pressure deficit and different soil characteristics may result not only from the mean change in tree responses (e.g. growth decrease or increase), but may also depend on how individual tree responses vary in relation to their size and how they cope with competition. There may be a large growth imbalance among trees as a function of their size, which is referred to as growth dominance. That is, a change in a factor may have different impacts on stand growth depending on stand structure and how growth is distributed. Thus, using an experimental platform spanning tropical Brazil, we explored the relationship between growth dominance and stand growth, and whether this relationship changes across a wide climatic gradient, represented by soil water deficit. We found a predominance of negative growth dominance during the early phase of stand development which increased until dominance became positive, after about 30 months, and kept increasing afterwards. Increasing soil water deficit slowed the increase in growth dominance throughout time. The intensification of growth dominance (either positive or negative) was associated with decreasing stand growth. Increasing soil water deficit decreased the negative effect of growth dominance on increment in absolute terms, but we showed that, at the end of a 5-year rotation, increasing growth dominance at a site with more intense water deficit led to a greater growth loss in relative terms than at a site with milder water deficit. For example, the estimated difference in increment between a stand with a low growth dominance of 0.05 and a stand with a high growth dominance of 0.20 at the end of a 60–month rotation at a site with an accumulated water deficit of −200 mm was about 28 m3 ha−1 year−1, which is equivalent to a 39% decrease in relative terms. This same GDC difference under a water stress of −4000 mm resulted in a decrease in increment of approximately 18 m3 ha−1 year−1, or 48% in relative terms.

SCREENING OF POST-MENOPAUSAL OSTEOPOROSIS BY ANTIOSTEOPOROTIC ACTIVITY

Postmenopausal osteoporosis, a quiet plague, has become a significant wellbeing danger, harassing about half of postmenopausal ladies around the world, and is accepted to be a malady that is one of the most well-known face to face who is encountering dementia achieved by mature age. It is a constant, dynamic condition, related with infinitesimal weakening of bone tissue, bringing about diminished bone mass, diminished bone quality which builds the danger of break.&#x0D; Ladies are bound to create osteoporosis than men because of decrease in estrogen during menopause which prompts decrease in bone-development and increment in bone-resorption action. Estrogen can stifle creation of proinflammatory cytokines like IL-1, IL-6, IL-7 and TNF-α. This is the reason these cytokines are raised in postmenopausal ladies. This paper manages the different techniques and parameters most every now and again utilized for screening of antiosteoporotic movement in post-menopausal osteoporesis. The ovariectomized creature model is the most proper model for considering the adequacy of various medications to forestall bone misfortune in postmenopausal osteoporosis. Different parameters dissected are: Biomechanical parameters as Three point bowing of tibia, Compression IV lumbar vertebra, Loading trial of femoral neck, Bone mineral thickness estimation; Biochemical parameters viz. serum calcium and inorganic phosphorus, serum basic phosphatase (ALP), Tartrate safe corrosive phosphatase (TRAP), protein profile, serum ACTH, corticosterone, IL-6, TNF-α, osteoprotegerin (OPG) and deoxypyridinoline crosslinks to creatinine proportion (DPD/Cr); Physical parameters like thickness and the length of the femur, weight of femur, Femur bone volume, bone thickness and so forth; Histopathology of femur to watch histopathological changes like size, shape and bone design; problematic and lytic changes, and fibrocartilageneous lattice with osteodystrophy; therapeutic advancement with mineralization alongside genuinely very much dispersed osteocytes; trabeculae and grid, and shaft size and so on; Histopathology of tibia to watch bone zone, bone volume per tissue volume, bone edge, outright number of dynamic osteoblasts, the proportion of indisputably the quantity of dynamic cuboid osteoblasts per bone border, the proportion of without a doubt the quantity of osteoclasts per osteoclast edge which speak to part of the trabeculae that are secured with osteoclasts, trabecular thickness, trabecular partition, trabecular number, mineralized bone volume per tissue volume, the osteoid volume per bone volume, the osteoid surface per bone surface, the osteoblast surface per bone surface, the disintegrated surface per bone surface. Different parameters as histopathology of uterus and mammary organ tissue, immunohistochemical recoloring to quantify ER level, pee examinations, body weight, organ weight, nourishment utilization, estrogen receptor ligand restricting test (ER-LBA), assurance of oxidative pressure, social test by constrained swimming test, neonatal mouse parietal bone resorption measure and so forth can likewise be completed.

Reduction of paediatric head CT utilisation at a rural general hospital emergency department

BackgroundBlunt head injury is a common pediatric injury and often evaluated in general emergency departments. It estimated that 50% of children will undergo a head computed tomography (CT), often unnecessarily...

Estimating the Impact of Switching from a Lower to Higher Valent Pneumococcal Conjugate Vaccine in Colombia, Finland, and The Netherlands: A Cost-Effectiveness Analysis.

IntroductionWidespread use of ten-valent (Synflorix™, GSK) or 13-valent (Prevenar 13™; Pfizer) conjugate vaccination programs has effectively reduced invasive pneumococcal disease (IPD) globally. However, IPD caused by serotypes not contained within the respective vaccines continues to increase, notably serotypes 3, 6A, and 19A in countries using lower-valent vaccines. Our objective was to estimate the clinical and economic benefit of replacing PCV10 with PCV13 in Colombia, Finland, and The Netherlands.MethodsCountry-specific databases, supplemented with published and unpublished data, informed the historical incidence of pneumococcal disease as well as direct and indirect medical costs. A decision-analytic forecasting model was applied, and both costs and outcomes were discounted. The observed invasive pneumococcal disease (IPD) trends from each country were used to forecast the future number of IPD cases given a PCV13 or PCV10 program.ResultsOver a 5-year time horizon, a switch to a PCV13 program was estimated to reduce overall IPD among 0–2 year olds by an incremental − 37.6% in Colombia, − 32.9% in Finland, and − 26% in The Netherlands, respectively, over PCV10. Adults > 65 years experienced a comparable incremental decrease in overall IPD in Colombia (− 32.2%), Finland (− 15%), and The Netherlands (− 3.7%). Serotypes 3, 6A, and 19A drove the incremental decrease in disease for PCV13 over PCV10 in both age groups. A PCV13 program was dominant in Colombia and Finland and cost-effective in The Netherlands at 1 × GDP per capita (€34,054/QALY).ConclusionIn Colombia, Finland, and The Netherlands, countries with diverse epidemiologic and population distributions, switching from a PCV10 to PCV13 program would significantly reduce the burden of IPD in all three countries in as few as 5 years.Electronic supplementary materialThe online version of this article (10.1007/s40121-020-00287-5) contains supplementary material, which is available to authorized users.

To see or not to see: Importance of color perception to color therapy

AbstractColor therapy, healing through color, supposedly works through the physical exposure to color. In two studies, we assessed stress and anxiety reduction after color exposure using a commercially available relaxation‐through‐color routine. Participants either completed the routine by looking at the accompanying color disks or at a white patch. In study 1 (longitudinal), 60 participants completed the routine three times, each testing session separated by a week. In study 2 (cross‐sectional), 63 participants completed half of the trials once. In both studies, we recorded a decrease in stress and anxiety levels comparing before‐after scores. In study 1, we recorded incremental decreases with each week. Crucially, decreases were the same whether participants (a) physically saw colors or not, and (b) completed the full or shortened version. We conclude that other factors but physical exposure to color explain changes in affective states associated with this and probably other color therapy routines.

A novel preoperative risk score to optimize patient selection for performing concomitant liver resection with cytoreductive surgery/HIPEC.

37 Background: While parenchymal hepatic metastases were previously considered a contraindication to cytoreductive surgery(CRS) and heated intraperitoneal chemotherapy(HIPEC), liver resection(LR) is increasingly performed concomitantly with CRS/HIPEC. As this practice continues to expand, identification of preoperative factors associated with poor outcomes is paramount. Methods: Patients from the US HIPEC Collaborative(2000-2017) with invasive appendiceal or colorectal adenocarcinoma undergoing primary, curative intent CRS/HIPEC with CC0-1 resection were included. LR was defined as a formal parenchymal resection. Primary endpoints were postoperative complications and overall survival(OS). Results: 658 patients were included. Average age was 54 years and 45% were male; 83 (15%) underwent liver resection of colorectal (58%) or invasive appendiceal (42%) metastases. Liver resection patients had more complications (81 vs 60%; p = 0.001), greater number of complications (2.3 vs 1.5; p &lt; 0.001), and required more reoperations (22 vs 11%; p = 0.007) and readmissions (39 vs 25%; p = 0.014) than non-liver resection patients. Liver resection patients had decreased OS (2-year OS 62% vs 79%, p &lt; 0.001), which persisted on multivariable Cox regression when accounting for PCI and histology type. Preoperative factors associated with decreased OS on multivariable analysis in patients undergoing liver resection included age &lt; 60 years (HR:3.61), colorectal histology (HR:3.84), and multiple liver tumors (HR:3.45) (all p &lt; 0.05). When assigning one point for each factor, there was an incremental decrease in 2-yr survival as the risk score increased from 0 to 3 (0: 100%; 1: 91%; 2: 58%; 3: 0%; p &lt; 0.001). Conclusions: As concurrent liver resection with CRS/HIPEC has become more common, we created a simple risk score to stratify patients considered for CRS/HIPEC with liver resection. These data aid in striking the balance between an increased perioperative complication profile with the potential for improvement in overall survival.

Reducing polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil using short-path molecular distillation

ABSTRACTBleached olive pomace oil (BOPO) was distilled using a short-path molecular distillation unit to determine the impacts of distillation conditions on the removal of 15 PAHs from the list of 16 EPA-priority pollutant PAHs. The removal of PAHs was achieved at elevated temperatures (110–230°C) and pressures (0.05, 0.5, 5 mbar). The oil was also deodorised at 230°C under 0.5, 1 and 5 mbar pressures to determine the effect of pressure during deodorisation on the removal of PAHs. High-performance liquid chromatography (HPLC) with fluorescence detector (HPLC-FLD) was used for quantifying PAH concentrations in oil samples. PAH concentrations in BOPO were considerably reduced after molecular distillation and both temperature increment and pressure decrease were effective for the removal of PAHs from olive pomace oil. When above 190°C, BaP could be reduced to <2 µg/kg at all pressures. Distillation at 230°C under 0.05 mbar absolute pressure reduced the sum of four PAHs (BaP, Chr, BaA, BbF) to 7 µg/kg, which meets the acceptable levels established by the European Union (10 µg/kg). Deodorisation effectiveness was increased by decreasing absolute pressure, particularly for light PAHs.

Different Geometries of Superheterodyne Amplification of Electromagnetic Beams in Waveguides Nitride-Dielectric

The superheterodyne amplification of electromagnetic waves is investigated when the resonant three-wave interaction of two electromagnetic waves with the space charge wave occurs in the waveguides nitride n-GaN, n-InN films-dielectric. The amplification of SCW waves due to the negative differential conductivity is investigated in nitride n-GaN, n-InN films at the frequencies f ≤ 400 GHz in the lower part of the terahertz (THz) range. The electromagnetic waves are either in the upper part of THz range or in the optical range. The superheterodyne amplification is considered in two geometries, the collinear one in which the three interacting waves travel in the same direction and the anti-collinear geometry where the second electromagnetic wave propagates in the opposite direction. The preferences and drawbacks of each geometry are pointed out. The finite width of space charge waves leads to decrease of increments of amplification.

In situ long-term membrane performance evaluation of hydrogen-bromine flow batteries

Because of the impracticality of long life time testing of hydrogen bromine flow batteries (HBFBs) under real, cyclic operating conditions, we utilized a high-frequency cycling load accelerated lifetime test (ALT) to evaluate the membrane electrode assembly performance in HBFBs. Four different membrane chemistries were tested to assess the relative long-term performance and durability of the corresponding HBFBs and to understand the main long-term failure mechanism in HBFB technology. The high-frequency cycling load ALT is a highly valuable method to assess long-term HBFB (components) stability and to understand the degradation/failure mechanism. The results showed that the utilization of long side chain perfluorosulfonic acid (LSC PFSA, i.e. Nafion®) membranes result in stable HBFB operation until a sudden cell failure at the end of the cycle life. The use of a more selective (lower bromine species crossover) reinforced LSC PFSA membrane results in approx. five times longer life times. In contrast, the use of a grafted polyvinylidene fluoride (SPVDF) membrane results in a slow incremental performance decrease (or area resistance increase) during the ALT and, again, a sudden cell failure at the end of the cycle life. After the ALT, the LSC PFSA membrane still shows high chemical stability. On the other hand, the grafted SPVDF and SPE membranes show clear membrane degradation visible as a strong decrease in IEC and an increase in ohmic AR. Gradual Pt catalyst degradation-dissolution, that results in insufficient Pt catalyst loading and subsequently low hydrogen reaction kinetics, is the main failure mechanism of the HBFBs. The membrane bromine species crossover rate is directly related to the rate of Pt catalyst degradation-dissolution and scales almost linearly with the cell total ampere-hours. As long as the catalyst loading is sufficient and does not reach a minimum value, this observed Pt degradation-dissolution rate does not significantly impact the cell performance.

Automated calcium scores collected during myocardial perfusion imaging improve identification of obstructive coronary artery disease

BackgroundMyocardial perfusion imaging (MPI) is an accurate noninvasive test for patients with suspected obstructive coronary artery disease (CAD) and coronary artery calcium (CAC) score is known to be a powerful predictor of cardiovascular events. Collection of CAC scores simultaneously with MPI is unexplored. AimWe aimed to investigate whether automatically derived CAC scores during myocardial perfusion imaging would further improve the diagnostic accuracy of MPI to detect obstructive CAD. MethodsWe analyzed 150 consecutive patients without a history of coronary revascularization with suspected obstructive CAD who were referred for 82Rb PET/CT and available coronary angiographic data. Myocardial perfusion was evaluated both semi quantitatively as well as quantitatively according to the European guidelines. CAC scores were automatically derived from the low-dose attenuation correction CT scans using previously developed software based on deep learning. Obstructive CAD was defined as stenosis >70% (or >50% in the left main coronary artery) and/or fractional flow reserve (FFR) ≤0.80. ResultsIn total 58% of patients had obstructive CAD of which seventy-four percent were male. Addition of CAC scores to MPI and clinical predictors significantly improved the diagnostic accuracy of MPI to detect obstructive CAD. The area under the curve (AUC) increased from 0.87 to 0.91 (p: 0.025). Sensitivity and specificity analysis showed an incremental decrease in false negative tests with our MPI + CAC approach (n = 14 to n = 4), as a consequence an increase in false positive tests was seen (n = 11 to n = 28). ConclusionCAC scores collected simultaneously with MPI improve the detection of obstructive coronary artery disease in patients without a history of coronary revascularization.