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To investigate discrepancies in dose calculation algorithms used for lung stereotactic body radiotherapy (SBRT) plans.
Methods and materials
In total, 30 patients lung SBRT treatment plans, initially generated using BrainLab Pencil Beam (BL_PB) algorithm for 10 Gy×5 Fractions to the planning target volume (PTV) were included in the study. These plans were recalculated using BrainLab Monte Carlo (BL_MC), Eclipse AAA (EC_AAA), Eclipse Acuros XB (EC_AXB) and ADAC Pinnacle CCC (AP_CCC) algorithms. Dose volume histograms of PTV were used to calculate dosimetric and radiobiological quality indices, and equivalent dose to 2 Gy per fraction using linear-quadratic-linear model. The BL_MC algorithm is considered gold standard tool to compare PTV parameters and quality indices to investigate dose calculation discrepancies of abovementioned plans.
BL_PB overestimates doses that may be due to inability of the algorithm to properly account for electron scattering and transport in inhomogeneous medium. Compared with BL_MCNO plans, the EC_AAA and EC_AXB yield lower homogeneity indices and overestimate the dose in the penumbra region, whereas AP_CCC plans were comparable for small PTV (≈8 cc) and had significant difference for large PTV.
BL_PB algorithm overestimates PTV doses than BL_MC calculated doses. The EC_AAA, EC_AXB and AP_CCC algorithms calculate doses within acceptable limits of radiotherapy dose delivery recommendations.
Climate change is increasingly forcing population displacement, better described by the phrase environmentally induced forced migration. Rising global temperatures, rising sea levels, increasing frequency and severity of natural disasters, and progressive depletion of life-sustaining resources are among the drivers that stimulate population mobility. Projections forecast that current trends will rapidly accelerate. This will lead to an estimated 200 million climate migrants by the year 2050 and create dangerous tipping points for public health and security.
Among the public health consequences of climate change, environmentally induced forced migration is one of the harshest and most harmful outcomes, always involving a multiplicity of profound resource and social losses and frequently exposing migrants to trauma and violence. Therefore, one particular aspect of forced migration, the effects of population displacement on mental health and psychosocial functioning, deserves dedicated focus. Multiple case examples are provided to elucidate this theme. (Disaster Med Public Health Preparedness. 2019;13:116–122)
Phased Array Feed (PAF) technology is the next major advancement in radio astronomy in terms of combining high sensitivity and large field of view. The Focal L-band Array for the Green Bank Telescope (FLAG) is one of the most sensitive PAFs developed so far. It consists of 19 dual-polarization elements mounted on a prime focus dewar resulting in seven beams on the sky. Its unprecedented system temperature of ~17 K will lead to a 3 fold increase in pulsar survey speeds as compared to contemporary single pixel feeds. Early science observations were conducted in a recently concluded commissioning phase of the FLAG where we clearly demonstrated its science capabilities. We observed a selection of normal and millisecond pulsars and detected giant pulses from PSR B1937+21.
We have investigated Kelvin-Helmholtz (K-H) instabilities for a homogeneous compressible plasma containing a uniform magnetic field and a linear velocity shear. A derivation of the relevant K-H dispersion equation and details regarding method of solution are given elsewhere (submitted to Mon. Not. R. Astr. Soc.). We present here an outline of our results.
Given steam-quality challenges at our facility, the financial impact of options for reopening the sterile processing service unit were explored; duration of closure was the major driver of costs. Other potential negative effects of operating-room shutdowns include injury to facility reputation, loss of staff, loss of reimbursements, and harm to residency programs.
The possible thermal history of the Moon is investigated by means of theoretical models. The calculations include the effects of melting and time-dependent redistribution of radioactive heat sources. The known constraints can best be satisfied by a model which is characterized by relatively high initial temperatures close to the melting range; melting and, consequently, fractionation and redistribution of radionuclides would occur during the first 1.5 × 109 yr and would then be followed by an effective cooling process. Heat flow measurements on the lunar surface should permit a distinction between such a completely fractionated model and a non-fractionated model or a model with restricted fractionation in the outer few hundred kilometers.
Sorted patterned ground refers to polygons, nets, or stripes defined by rocky borders which are the result of sorting in soil subjected to frost action. This paper presents a model in which convection cells, driven by unstable density stratification in the aqueous phase, result in uneven melting of the underlying ice front during thawing. The resulting undulatory ice front with regularly spaced peaks and troughs provides the pattern which results in the regularity observed for certain types of patterned ground. In addition, the model predicts the width to depth-of-sorting ratio for both polygons and stripes, and explains the characteristic hexagonal shape of sorted polygons, the transition from sorted polygons to sorted stripes on sloped terrain, and the formation of sorted polygons under water. The predicted ratio of width to depth-of-sorting of 3.81 for sorted polygons is compared with the ratio of width to depth-of-sorting of 3.57 found from a linear regression analysis of 18 field study data.
In this paper, we experimentally study the unique surface sensing property and enhanced sensitivity in subwavelength grating (SWG) based microring resonator biosensors versus conventional ring resonator biosensors. In contrast to a conventional ring, the effective sensing region in the SWG microring resonator includes not only the top and side of the waveguide, but also the space between the silicon pillars on the propagation path of the optical mode. It leads to an unique property of thickness-independent surface sensitivity versus common evanescent wave sensors; in other words, the surface sensitivity remains constantly high with progressive attachment of biomolecules to the sensor surface. To increase the robustness of performance of ring shaped circular SWG biosensors, we experimentally demonstrate silicon SWG racetrack resonators. A quality factor of 9800 and bulk sensitivity (S) is ∼429.7 nm/RIU (refractive index per unit) results in an intrinsic detection limit (iDL) 3.71×10-4 RIU in racetrack SWG biosensors while still retaining the accumulated surface thickness properties of circular rings.
In this article, we use Mellin transforms to derive alternative results for option pricing and implied volatility estimation when the underlying asset price is governed by jump-diffusion dynamics. The current well known results are restrictive since the jump is assumed to follow a predetermined distribution (e.g., lognormal or double exponential). However, the results we present are general since we do not specify a particular jump-diffusion model within the derivations. In particular, we construct and derive an exact solution to the option pricing problem in a general jump-diffusion framework via Mellin transforms. This approach of Mellin transforms is further extended to derive a Dupire-like partial integro-differential equation, which ultimately yields an implied volatility estimator for assets subjected to instantaneous jumps in the price. Numerical simulations are provided to show the accuracy of the estimator.
Large volumes of data and multiple computing platforms are now universal components of paediatric cardiovascular medicine, but are in a constant state of evolution. Often, multiple sets of related data reside in disconnected “silos”, resulting in clinical, administrative, and research activities that may be duplicative, inefficient, and at times inaccurate. Comprehensive and integrated data solutions are needed to facilitate these activities across congenital heart centres. We describe methodology, key considerations, successful use cases, and lessons learnt in developing an integrated data platform across our congenital heart centre.
Two dimensional spectro-imaging of the planetary nebula NGC 40 was done to create spatially resolved intensity and electron density images. The CCD images, taken in Hβ, [S ii] λ6717, and [S ii] λλ6717, 6731, were calibrated, then correlated using previously published spectroscopic and photometric data of NGC 40 as a flux standard.
We present maps in the visible emission lines of [S II] and the infrared emission lines of H2, at 2.12μm, for several bipolar outflow complexes which exhibit jet structures. A comparison of the morphology of this infrared emission and that seen in visible emission lines shows both the visible and the H2 emission exhibit clumpy structure on similar scales. It appears that the brightest H2 emission occurs at the working surfaces of the jets. Virtually no H2 emission is associated with the jets themselves.
Velocity profiles are presented for several objects and possible emission mechanisms are discussed.
This study evaluated dosimetric parameters for cervical high-dose-rate (HDR) brachytherapy treatment using varying dose prescription methods.
This study includes 125 tandem-based cervical HDR brachytherapy treatment plans of 25 patients who received HDR brachytherapy. Delineation of high-risk clinical target volumes (HR-CTVs) and organ at risk were done on original computed tomographic images. The dose prescription point was defined as per International Commission in Radiation Units and Measurements Report Number 38 (ICRU-38), also redefined using American Brachytherapy Society (ABS) 2011 criteria. The coverage index (V100) for each HR-CTV was calculated using dose volume histogram parameters. A plot between HR-CTV and V100 was plotted using the best-fit linear regression line (least-square fit analysis).
Mean prescribed dose to ICRU-38 Point A was 590·47±28·65 cGy, and to ABS Point A was 593·35±30·42 cGy. There was no statistically significant difference between planned ICRU-38 and calculated ABS Point A doses (p=0·23). The plot between HR-CTV and V100 is well defined by the best-fit linear regression line with a correlation coefficient of 0·9519.
For cervical HDR brachytherapy, dose prescription to an arbitrarily defined point (e.g., Point A) does not provide consistent coverage of HR-CTV. The difference in coverage between two dose prescription approaches increases with increasing CTV. Our ongoing work evaluates the dosimetric consequences of volumetric dose prescription approaches for these patients.
The structure and the size of the core of massive presupernova stars are determined by the electron fraction and entropy of the core during its late stages of evolution; these in turn affect the subsequent evolution during gravitational collapse and supernova explosion phases. Beta decay and electron capture on a number of neutron rich nuclei can contribute substantially towards the reduction of the entropy and possibly the electron fraction in the core. Methods for calculating the weak transition rates for a number of nuclei for which no reliable rates exist (particularly for A > 60) are outlined. The calculations are particularly suited for presupernova matter density (p = 107 - 109 g/cc) and temperature (T = 2 - 6 × 109 °K). We include besides the contributions from the ground state and the known excited states, the Gamow-Teller (GT) resonance states (e.g. for beta decay rates, the GT+ states) in the mother nucleus which are populated thermally. For the GT strength function for transitions from the ground state (as well as excited states) we use a sum rule calculated by the spectral distribution method where the centroid of the distribution is obtained from experimental data on (p,n) reactions. The contribution of the excited levels and GT+ resonances turn out to be important at high temperatures which may prevail in presupernova stellar cores.
The present observational problem of understanding the nature and origin of comets is analogous to that we would face in attempting to understand a planet and its atmosphere if we possessed only data on its ionosphere and exosphere. Virtually everything we can observe remotely is a part of the rapidly escaping gas and dust atmosphere of the comet.
The response to sulphur (S) and irrigation of mustard although site-specific, is less studied across sites. Economics and greenhouse gases (GHGs) emissions are other important considerations for developing resource-efficient technologies, but hardly studied in mustard. The objectives of this study were to appraise productivity, economics and GHGs emissions under three irrigation regimes combined with four levels of S, laid out in a split plot design with three replications. Results showed that two irrigations at 30 and 60 DAS combined with 60 kg S ha−1 resulted in highest gross and net returns, which were 30.9 and 37.2% higher than that in single irrigation at 30 DAS, and 47.2 and 68.0% higher than that in single irrigation at 60 DAS without S application, respectively. Estimated GHGs emissions from common inputs (machinery, diesel, fertilizer and insecticides) of mustard were 1486.2 kg CO2 eq ha−1 with greater share (95%) of fertilizer. Econometric analysis predicts that 1% increase in irrigation and S use will lead to 10.29 and 9.98% increase in mustard yield, respectively.
Patients with candidemia are at risk for other invasive infections, such as methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI).
To identify the risk factors for, and outcomes of, BSI in adults with Candida spp. and MRSA at the same time or nearly the same time.
Population-based cohort study.
Metropolitan Atlanta, March 1, 2008, through November 30, 2012.
All residents with Candida spp. or MRSA isolated from blood.
The Georgia Emerging Infections Program conducts active, population-based surveillance for candidemia and invasive MRSA. Medical records for patients with incident candidemia were reviewed to identify cases of MRSA coinfection, defined as incident MRSA BSI 30 days before or after candidemia. Multivariate logistic regression was performed to identify factors associated with coinfection in patients with candidemia.
Among 2,070 adult candidemia cases, 110 (5.3%) had coinfection within 30 days. Among these 110 coinfections, MRSA BSI usually preceded candidemia (60.9%; n=67) or occurred on the same day (20.0%; n=22). The incidence of coinfection per 100,000 population decreased from 1.12 to 0.53 between 2009 and 2012, paralleling the decreased incidence of all MRSA BSIs and candidemia. Thirty-day mortality was similarly high between coinfection cases and candidemia alone (45.2% vs 36.0%, P=.10). Only nursing home residence (odds ratio, 1.72 [95% CI, 1.03–2.86]) predicted coinfection.
A small but important proportion of patients with candidemia have MRSA coinfection, suggesting that heightened awareness is warranted after 1 major BSI pathogen is identified. Nursing home residents should be targeted in BSI prevention efforts.
Infect. Control Hosp. Epidemiol. 2015;36(11):1298–1304
Spectra of infrared sources associated with molecular clouds have shown absorption features at wavelengths of 6.0 and 6.8 μm. We suggest that the 6.0 μm feature can be identified with the stretching vibration of C=0 and the 6.8 μm feature with the bending vibrations of CH2 and CH3. The amount of carbon in the form of hydrocarbon molecules may be comparable to the amount in CO. This abundance of hydrocarbons is probably too large to be consistent with radio observations if the molecules are gaseous, but large abundances of hydrocarbons on the surfaces of grains may explain the infrared features, yet be unobservable in the radio.
We present a novel motorized semi-autonomous mobile hospital bed guided by a human operator and a reactive navigation algorithm. The proposed reactive navigation algorithm is launched when the sensory device detects that the hospital bed is in the potential danger of collision. The semi-autonomous hospital bed is able to safely and quickly deliver critical neurosurgery (head trauma) patients to target locations in dynamic uncertain hospital environments such as crowded hospital corridors while avoiding en-route steady and moving obstacles. We do not restrict the nature or the motion of the obstacles, meaning that the shapes of the obstacles may be time-varying or deforming and they may undergo arbitrary motions. The only information available to the navigation system is the current distance to the nearest obstacle. Performance of the proposed navigation algorithm is verified via theoretical studies. Simulation and experimental results also confirm the performance of the reactive navigation algorithm in real world scenarios.