Modeling Air Traffic Demand for a Real-Time Queuing Network Model of the National Airspace System

predictive model for departure traffic demand and its route distribution at look-ahead times of 2-15 hours is proposed, for use in a queuing-network-based tool for strategic Traffic Flow Management (TFM). The proposed model uses a combination of operational data (filed flight plans, schedules), historical statistics of demand, and time- of-operation-specific factors to generate statistical predictions of traffic demand for particular routes between pairs of airports or airport clusters. Specifically, a two-stage predictor for demand is proposed. First, traffic demand for an origin-destination (O-D) pair is modeled as the summation of a known demand which captures filed and scheduled traffic, and an unknown demand which is modeled as non-homogeneous Poisson process. Second, the fraction of this O-D traffic demand on each route is modeled using a linear regression, with the historical route fractions, known (filed) route fractions, and wind-adjusted transit times for the routes serving as regressors. Historical data on demands and actual traffic volumes are used to evaluate aspects of the model, including the Poisson-process assumption and the regression model for route distributions

A Modified Self-Growing Rod Technique for Treatment of Early-Onset Scoliosis

Background: Surgical treatment of early-onset scoliosis (EOS) remains challenging as no definitive surgical technique has emerged as the single best option in this varied patient population(1-3). Although the available surgical techniques may differ substantially, they all share the same goals of achieving and maintaining deformity correction, allowing physiological spinal growth, and reducing the number of operations and complications. Herein, we present a modified self-growing rod technique that represents a valid alternative to the existing surgical procedures for EOS.Description: The patient is positioned prone on a radiolucent table, and the spine is prepared and draped in a standard fashion. A posterior midline skin incision is made from the upper to the lower instrumented level. Subperiosteal exposure of the spine is carried out, ensuring that capsules of the facet joints are spared. Pedicle screws are inserted bilaterally at the cranial and caudal ends of the instrumentation. Fixation with pedicle screws of at least 3 levels at the top and bottom end is usually advised; in nonambulatory patients with pelvic obliquity, caudal fixation can be extended to the pelvis with bilateral iliac screws. Sublaminar wires are positioned bilaterally at every level between the cranial and caudal ends of the instrumentation and are passed as medially as possible to avoid damage to the facet joints. Four 5-mm cobalt-chromium rods are cut, contoured, and inserted at each end of the construct. Ipsilateral rods are secured with use of sublaminar wires, making sure that they overlap over a sufficient length to allow for the remaining spinal growth. Correction of the deformity is achieved with use of a combination of cantilever maneuvers and apical translation by progressive and sequential tightening of the sublaminar wires. The wound is closed in layers over a subfascial drain. The patient is allowed free mobilization after surgery. No postoperative brace is required.Alternatives: Nonoperative alternative treatment for EOS includes serial cast immobilization and bracing(4). Alternative surgical treatments include traditional growing rods(5), magnetically controlled growing rods(6), the vertical expandable prosthetic titanium rib-expansion technique(7), and the Shilla technique(8). The use of compression-based systems (i.e., staples or tether)(9) or early limited fusion has also been reported by other authors.Rationale: The main advantage of our technique is that it relies on physiological spinal growth and does not require surgery or external devices for rod lengthening, which is particularly beneficial in frail patients with a neuromuscular disease in whom repeated surgery is not advised. Segmental fixation by sublaminar wires allows good control of the deformity apex during growth. Concerns regarding early fusion of the spine have not been confirmed in our mid-term follow-up study(10).Expected Outcomes: This technique allows correction of the deformity and continuous spinal growth in the years following surgery. At 6.0 years postoperatively, the average main curve correction was reported to be 61% and the average pelvic obliquity correction was 69%. The spine was reported to lengthen an average of 40.9 mm (range, 14.0 to 84.0 mm) immediately postoperatively, and the T1-S1 segment was reported to continue growing at 10.5 mm/year (range, 3.6 to 16.5 mm/year) thereafter(10). The most common complication is rod breakage at the thoracolumbar junction, which seems to be more common in patients with idiopathic or cerebral palsy EOS and during the pubertal growth spurt(10).Important Tips: Subperiosteal exposure of the spine should be carried out, making sure to preserve facet joints in the unfused area of the spine. Achieve segmental fixation with use of sublaminar wires at every level and pedicle screws at the top and bottom ends of the instrumentation. If pelvic imbalance is present and the patient is nonambulatory, pelvic fixation with iliac screws is advised. First round correction of the deformity is achieved with a cantilever technique; correction fine-tuning can be performed by tightening sublaminar wires. Consider utilizing thicker rods in cases of idiopathic or cerebral palsy EOS

Evaluation of SWIR Crop Residue Bands for the Landsat Next Mission

This research reports the findings of a Landsat Next expert review panel that evaluated the use of narrow shortwave infrared (SWIR) reflectance bands to measure ligno-cellulose absorption features centered near 2100 and 2300 nm, with the objective of measuring and mapping non-photosynthetic vegetation (NPV), crop residue cover, and the adoption of conservation tillage practices within agricultural landscapes. Results could also apply to detection of NPV in pasture, grazing lands, and non-agricultural settings. Currently, there are no satellite data sources that provide narrowband or hyperspectral SWIR imagery at sufficient volume to map NPV at a regional scale. The Landsat Next mission, currently under design and expected to launch in the late 2020’s, provides the opportunity for achieving increased SWIR sampling and spectral resolution with the adoption of new sensor technology. This study employed hyperspectral data collected from 916 agricultural field locations with varying fractional NPV, fractional green vegetation, and surface moisture contents. These spectra were processed to generate narrow bands with centers at 2040, 2100, 2210, 2260, and 2230 nm, at various bandwidths, that were subsequently used to derive 13 NPV spectral indices from each spectrum. For crop residues with minimal green vegetation cover, two-band indices derived from 2210 and 2260 nm bands were top performers for measuring NPV (R2 = 0.81, RMSE = 0.13) using bandwidths of 30 to 50 nm, and the addition of a third band at 2100 nm increased resistance to atmospheric correction residuals and improved mission continuity with Landsat 8 Operational Land Imager Band 7. For prediction of NPV over a full range of green vegetation cover, the Cellulose Absorption Index, derived from 2040, 2100, and 2210 nm bands, was top performer (R2 = 0.77, RMSE = 0.17), but required a narrow (≤20 nm) bandwidth at 2040 nm to avoid interference from atmospheric carbon dioxide absorption. In comparison, broadband NPV indices utilizing Landsat 8 bands centered at 1610 and 2200 nm performed poorly in measuring fractional NPV (R2 = 0.44), with significantly increased interference from green vegetation

Optimizing Landsat Next Shortwave Infrared Bands for Crop Residue Characterization

This study focused on optimizing the placement of shortwave infrared (SWIR) bands for pixel-level estimation of fractional crop residue cover (fR) for the upcoming Landsat Next mission. We applied an iterative wavelength shift approach to a database of crop residue field spectra collected in Beltsville, Maryland, USA (n = 916) and computed generalized two- and three-band spectral indices for all wavelength combinations between 2000 and 2350 nm, then used these indices to model field-measured fR. A subset of the full dataset with a Normalized Difference Vegetation Index (NDVI) fR estimation. For the two-band wavelength shift analyses applied to the NDVI fR estimation performance (R2 = 0.8222; RMSE = 0.1296). These findings were similar to the established two-band Shortwave Infrared Normalized Difference Residue Index (SINDRI) (R2 = 0.8145; RMSE = 0.1324). Performance of the two-band generalized normalized difference and SINDRI decreased for the full-NDVI dataset (R2 = 0.5865 and 0.4144, respectively). For the three-band wavelength shift analyses applied to the NDVI R2 = 0.8397; RMSE = 0.1231). Three-band indices with CAI-type wavelengths maintained top fR estimation performance for the full-NDVI dataset with a 2036–2111–2217 nm band combination (R2 = 0.7581; RMSE = 0.1548). The 2036–2111–2217 nm band combination was also top performing in fR estimation (R2 = 0.8690; RMSE = 0.0970) for an additional analysis assessing combined green vegetation cover and surface moisture effects. Our results indicate that a three-band configuration with band centers and wavelength tolerances of 2036 nm (±5 nm), 2097 nm (±14 nm), and 2214 (±11 nm) would optimize Landsat Next SWIR bands for fR estimation

Evaluating the sensitivity and specificity of promising circulating biomarkers to diagnose liver injury in humans

Early diagnosis of drug-induced liver injury (DILI) continues to be a major hurdle during drug development and post marketing. The objective of this study was to evaluate the diagnostic performance of promising biomarkers of liver injury - glutamate dehydrogenase (GLDH), cytokeratin-18 (K18), caspase-cleaved K18 (ccK18), osteopontin (OPN), macrophage colony-stimulating factor (MCSF), MCSF receptor (MCSFR), and microRNA-122 (miR-122) in comparison to the traditional biomarker alanine aminotransferase (ALT). Biomarkers were evaluated individually and as a multivariate model in a cohort of acetaminophen overdose (n=175) subjects and were further tested in cohorts of healthy adults (n=135), patients with liver damage from various causes (n=104), and patients with damage to the muscle (n=74), kidney (n=40), gastrointestinal tract (n=37) and pancreas (n=34). In the acetaminophen cohort, a multivariate model with GLDH, K18 and miR-122 was able to detect DILI more accurately than individual biomarkers alone. Furthermore, the three-biomarker model could accurately predict patients with liver injury compared to healthy volunteers or patients with damage to muscle, pancreas, gastrointestinal tract and kidney. Expression of K18, GLDH ad miR-122 was evaluated using a database of transcriptomic profiles across multiple tissues/organs in humans and rats. K18 mRNA (Krt18) and MiR-122 were highly expressed in liver whereas GLDH mRNA (Glud1) was widely expressed. We performed a comprehensive, comparative performance assessment of seven promising biomarkers and demonstrated that a three-biomarker multivariate model can accurately detect liver injury