摘要 :
A 1D corona discharge model coupled to a 2D-axisymmetric particle charging model are proposed in this paper to simulate nanoparticle charging process within a wire-tube air corona discharge subjected to an applied positive or nega...
展开
A 1D corona discharge model coupled to a 2D-axisymmetric particle charging model are proposed in this paper to simulate nanoparticle charging process within a wire-tube air corona discharge subjected to an applied positive or negative dc voltage. This 1D discharge model provides the distribution of the electric field, the air ion and free electron concentrations for the 2D charging model which in turn solves the spatial distributions of the various charged nanoparticles within the tube. This 2D charging model takes into account the effect of electrons, on the basis of Fuchs' law usually employed in the literature for modelling of ion diffusion nanoparticle charging. The current approach is valid when the concentration of nanoparticles is much lower than the concentration of ionic species in the gas. Numerical results show that the positive air ions can be assumed to be solely responsible for the charging process in a positive air corona charger, while both the negative air ions and electrons play an important role in the negative charging. At high negative charge intensities, the effect of the electrons becomes appreciable due to their high conduction velocity. In general, the numerical results obtained are in good agreement with the experimental data reported in the literature.
收起
摘要 :
Automatic segmentation of the left ventricle (LV) in late gadolinium enhanced (LGE) cardiac MR (CMR) images is difficult due to the intensity heterogeneity arising from accumulation of contrast agent in infarcted myocardium. In th...
展开
Automatic segmentation of the left ventricle (LV) in late gadolinium enhanced (LGE) cardiac MR (CMR) images is difficult due to the intensity heterogeneity arising from accumulation of contrast agent in infarcted myocardium. In this paper, we present a comprehensive framework for automatic 3D segmentation of the LV in LGE CMR images. Given myocardial contours in cine images as a priori knowledge, the framework initially propagates the a priori segmentation from cine to LGE images via 2D translational registration. Two meshes representing respectively endocardial and epicardial surfaces are then constructed with the propagated contours. After construction, the two meshes are deformed towards the myocardial edge points detected in both short-axis and long-axis LGE images in a unified 3D coordinate system. Taking into account the intensity characteristics of the LV in LGE images, we propose a novel parametric model of the LV for consistent myocardial edge points detection regardless of pathological status of the myocardium (infarcted or healthy) and of the type of the LGE images (short-axis or long-axis). We have evaluated the proposed framework with 21 sets of real patient and four sets of simulated phantom data. Both distance- and region-based performance metrics confirm the observation that the framework can generate accurate and reliable results for myocardial segmentation of LGE images. We have also tested the robustness of the framework with respect to varied a priori segmentation in both practical and simulated settings. Experimental results show that the proposed framework can greatly compensate variations in the given a priori knowledge and consistently produce accurate segmentations.
收起
摘要 :
OBJECTIVE:: We hypothesized that deficiency in 25-hydroxyvitamin D prior to hospital admission would be associated with sepsis in the critically ill. DESIGN:: Two-center observational study of patients treated in medical and surgi...
展开
OBJECTIVE:: We hypothesized that deficiency in 25-hydroxyvitamin D prior to hospital admission would be associated with sepsis in the critically ill. DESIGN:: Two-center observational study of patients treated in medical and surgical ICUs. SETTING:: Two hundred nine medical and surgical intensive care beds in two teaching hospitals in Boston, MA. PATIENTS:: Three thousand three hundred eighty-six patients, 18 years old or older, in whom 25-hydroxyvitamin D was measured prior to hospitalization between 1998 and 2011. INTERVENTIONS:: None MEASUREMENTS AND MAIN RESULTS:: Preadmission 25-hydroxyvitamin D was categorized as deficiency in 25-hydroxyvitamin D (≤ 15 ng/mL), insufficiency (15-30 ng/mL), and sufficiency (≥ 30 ng/mL). The primary outcome was sepsis as defined by International Classification of Diseases, 9th Edition, Clinical Modification and validated by the 2001 Society of Critical Care Medicine/European Society of Intensive Care Medicine, American College of Chest Physicians, American Thoracic Society, and Surgical Infection Society international sepsis definitions conference guidelines. Logistic regression examined the presence of sepsis 3 days prior to critical care initiation to 7 days after critical care initiation. Adjusted odds ratios were estimated by multivariable logistic regression models. Preadmission 25-hydroxyvitamin D deficiency is predictive for the risk of sepsis. In the full cohort, 25-hydroxyvitamin D deficiency is a significant predictor for the risk of International Classification of Diseases, 9th Edition, Clinical Modification-defined sepsis following multivariable adjustment, including age, gender, race, type (surgical vs medical), and Deyo-Charlson index (adjusted odds ratio, 1.51 [95% CI, 1.17-1.94]; p = 0.001) relative to patients with 25-hydroxyvitamin D sufficiency. In a subset of cohort patients enriched for those with International Classification of Diseases, 9th Edition, Clinical Modification-diagnosed sepsis (n = 444), preadmission 25-hydroxyvitamin D deficiency is a significant predictor for the risk of conference guideline-defined sepsis following multivariable adjustment, including age, gender, race, type (surgical vs medical), and Acute Physiology and Chronic Health Evaluation II (adjusted odds ratio, 2.05 [95% CI, 1.19-3.52]; p = 0.009) relative to patients with 25-hydroxyvitamin D sufficiency. Furthermore, in cohort patients with International Classification of Diseases, 9th Edition, Clinical Modification-defined sepsis (n = 568), the multivariable adjusted risk of 90-day mortality was 1.6-fold higher in those with preadmission 25-hydroxyvitamin D values in the insufficient and deficient range, compared with those with preadmission vitamin D sufficiency (adjusted odds ratio, 1.63 [95% CI, 1.11-2.39]; p = 0.01). CONCLUSION:: 25-hydroxyvitamin D deficiency prior to hospital admission is a significant predictor of sepsis in the critically ill. Additionally, patients with sepsis who are not vitamin D sufficient have an increased risk of mortality following critical care initiation.
收起
摘要 :
We have ionized H-2 molecules in intense fields of a 6-ns pulsed Nd:YAG laser at the fundamental, second, and third harmonic wavelengths (lambda = 1064, 532, and 355 nm) and measured the relative population of the vibrational leve...
展开
We have ionized H-2 molecules in intense fields of a 6-ns pulsed Nd:YAG laser at the fundamental, second, and third harmonic wavelengths (lambda = 1064, 532, and 355 nm) and measured the relative population of the vibrational levels of the H-2(+) molecular ions that were thus produced. In comparison with the standard Franck-Condon overlap between the ground state of the neutral molecule and the vibrational levels of the ion, the population is very much shifted towards the lower levels, the more so for shorter wavelengths. In fact, for 355 nm, the shift is so large that practically only the v' = 0 level is populated. At 1064 run, the experimental results compare well with the predictions from a model developed recently on the basis of tunneling ionization directly from the around state of H-2. At shorter wavelengths, transient excitation must be invoked, either to field-dressed ionic states, H+H-, or to short lived resonances in Rydberg, states. [References: 19]
收起
摘要 :
Background: Administration of vitamin D to unselected heterogeneous critically ill patients did not demonstrate outcome benefit. The current study was undertaken to identify if early administration of vitamin D can reduce intensiv...
展开
Background: Administration of vitamin D to unselected heterogeneous critically ill patients did not demonstrate outcome benefit. The current study was undertaken to identify if early administration of vitamin D can reduce intensive care unit (ICU) length of stay and improve clinical outcomes in critically ill patients with sepsis. Methods: This single-center randomized double-blind placebo-controlled trial was done in the ICU and emergency inpatient ward of a tertiary care teaching institute in New Delhi, India. A total of 126 adult patients aged 18 to 80 years of either sex diagnosed to have sepsis were included within 24 hours of admission to the hospital and randomized into vitamin D or placebo groups. The patients in the intervention group received vitamin D3 540,000 units dissolved in 45 mL of milk. The placebo group received 45 mL of milk. Results: The median length of ICU stay (8 vs 9 days; p = 0.32), median length of hospital stay (12 vs 12 days; p = 0.33), median duration of vasopressors requirement (4 vs 3 days; p= 0.84), median duration of mechanical ventilation (5 vs 7 days; p= 0.23), requirement of tracheostomy (34 vs 39%; p = 0.71), and 90-day mortality [35 vs 46%; p = 0.29; HR 0.72 (0.42–1.24)] were similar in vitamin D and placebo arm. A subgroup analysis in patients with severe vitamin D deficiency (vitamin D <12 ng/mL) revealed a significantly decreased incidence of tracheostomy (28 vs 57%; p = 0.04), a trend toward decreased 90-day mortality [34 vs 66%; p = 0.08; HR 0.44 (0.19–1.01)], and duration of mechanical ventilation (6 vs 11 days; p = 0.05) in patients receiving vitamin D. Conclusion: Administration of large-dose vitamin D within 24 hours of admission does not reduce the length of ICU stay in critically ill sepsis patients.
收起
摘要 :
The present paper analyzes manufacturing density effect on the mechanical properties of three-dimensional (3D) printed ABS specimens. Indeed, the optimum density of the printed specimens is investigated to reach the extruded speci...
展开
The present paper analyzes manufacturing density effect on the mechanical properties of three-dimensional (3D) printed ABS specimens. Indeed, the optimum density of the printed specimens is investigated to reach the extruded specimens’ characteristics. Then, the mechanical properties such as the tensile strength, the Young’s modulus, the ultimate tensile and yield strength, the ductility and fracture toughness are identified and compared. Furthermore, we study crosshead speed effect on printed samples with an infill rate of 100% towards crack propagation. Subsequently, the stress intensity factor is determined. The results indicate a considerable effect of the density and the filling rate on tensile properties and on the rupture propagation.
收起
摘要 :
Objective : Vitamin D deficiency is a major health problem in all age groups. In the present study, we aimed to determine the prevalence of vitamin D deficiency in neonates hospitalized in an intensive care unit (NICU) and its ass...
展开
Objective : Vitamin D deficiency is a major health problem in all age groups. In the present study, we aimed to determine the prevalence of vitamin D deficiency in neonates hospitalized in an intensive care unit (NICU) and its association with clinical neonatal outcomes. Materials and methods : A prospective cross-sectional study was carried out on all neonates hospitalized in the NICU of Children's Medical Center over a period of one year (January–December 2018). Immediately on admission, a serum sample for vitamin D measurement was obtained with another routine blood sampling. Demographic and clinical data including sex, gestational age, the season of birth, serum levels of vitamin D and calcium, the causes of hospitalization, age at admission and neonatal outcomes including length of hospital stay and mortality during hospitalization were assessed. Results : One hundred neonates entered the study. Vitamin D deficiency and insufficiency were present in 95% of neonates. There was a significant association between vitamin D status and birth during winter (p=0.014); hypocalcemia (p=0.025) and older age at NICU admission (p<0.001). The mean value of vitamin D in term neonates was significantly lower than in preterm neonates (p=0.031). There were no correlations between length of hospital stay and neonatal mortality rate with vitamin D status (p=0.876). Conclusion : Vitamin D deficiency and insufficiency were highly prevalent among NICU patients. Maternal vitamin D supplementation during pregnancy may prevent or reduce the risk of low levels of vitamin D in neonates.
收起
摘要 :
A systematic study of the relative x-ray intensity ratios of the K- and L-series lines was made on compounds of Fe, Pt and U to examine the influence of chemical state on energy-dispersive x-ray fluorescence analysis. The measurem...
展开
A systematic study of the relative x-ray intensity ratios of the K- and L-series lines was made on compounds of Fe, Pt and U to examine the influence of chemical state on energy-dispersive x-ray fluorescence analysis. The measurements were done using an energy-dispersive Si(Li) detector with photon excitation by radioisotopes, It was shown that reliable x-ray intensity ratios can be derived by employing well-defined experimental conditions. For Fe a significant dependence of the K alpha and K beta x-ray yields per incident photon on the oxidation state of Fe was observed but no discernible effect on the Fe K beta/K alpha intensity ratio was observed. Likewise, no significant effect of chemical state on the various L-series intensity ratios of Pt and U was observed. For the L-series the seldom quoted intensity ratios L beta(2)/L alpha, L beta(1)/L alpha, L eta/L alpha and L beta(6)/L alpha were also measured and reported. The measured intensity ratios agree fairly well with the theoretical values of Scofield, Copyright (C) 2000 John Wiley & Sons, Ltd. [References: 23]
收起
摘要 :
R and D is necessary for growth of hi-tech sectors like pharmaceuticals and is aimed at boosting innovation. Innovation brings new products that could earn revenues to further boost R and D. Indian pharmaceutical industry earns ne...
展开
R and D is necessary for growth of hi-tech sectors like pharmaceuticals and is aimed at boosting innovation. Innovation brings new products that could earn revenues to further boost R and D. Indian pharmaceutical industry earns nearly sixty percent of its revenues from exports and is a leader in global generics market with largest share of ANDA and DMF filings. Significant increase in patenting activity is also observed post India's accession to TRIPS agreement in 1995 and subsequent introduction of product patent regime in 2005. This study aims at establishing a causal relationship amongst R and D intensity, patents, regulatory filings and export intensity. Also, the impact of these variables on export intensity of Indian pharmaceutical sector has been studied by fitting them into an econometric model. Results of the econometric analysis suggested that the current year R and D intensity had a positive and significant impact on pharmaceutical export intensity and that the lagged year regulatory filings had a positive and significant impact on export intensity of Indian pharmaceutical industry. Study concluded that creation of state-of-the-art R and D facilities and manufacturing plants (complying with US and EU norms) was aimed at developing and exporting generic drugs to regulated markets of US and Europe and Indian pharmaceutical industry had not committed enough financial resources on developing new patented products for global markets.
收起
摘要 :
Gynecologic cancers are often asymmetric, yet current Ir-192 brachytherapy techniques provide only limited radial modulation of the dose. The shielded solutions investigated here solve this by providing the ability to modulate bet...
展开
Gynecologic cancers are often asymmetric, yet current Ir-192 brachytherapy techniques provide only limited radial modulation of the dose. The shielded solutions investigated here solve this by providing the ability to modulate between highly asymmetric and radially symmetric dose distributions at a given location. To find applicator designs that can modulate between full dose and less than 50% dose, at the dimensions of the urethra, a 2D calculation algorithm was developed to narrow down the search space. Two shielding design types were then further investigated using Monte Carlo and Boltzmann-solver dose calculation algorithms. 3D printing techniques using ISO 10993 certified biocompatible plastics and 3D printable tungsten-loaded plastics were tested. It was also found that shadowing effects set by the shape of the shielding cannot be easily modulated out, hence careful design is required. The shielded applicator designs investigated here, allow for reduction of the dose by over 50% at 5 mm from the applicator surface in desired regions, while also allowing radially symmetric dose with isodose line deviations less than 0.5 mm from circular. The shielding designs were also chosen with treatment delivery time in mind. Treatment times for these shielded designs were found to be less than 1.4 times longer than a 6-channel unshielded cylinder for the equivalent fully symmetric dose distribution. The 2D calculation methods developed here provide a simple way to rapidly evaluate shielding designs, while the 3D printing techniques also allow for devices with novel shapes to be rapidly prototyped. Both TOPAS Monte Carlo and Acuros BV calculations show that significant dose shaping and organ at risk sparing can be achieved without significantly compromising the plan in regions that require the full dose.
收起
原文获取