Supervised discretization for decluttering classification models.

Presented here is the first demonstration of supervised discretization to 'declutter' multivariate classification data in chemical sensor applications. The performance of multivariate classification models is often limited by the non-informative chemical variance within each target class; decluttering methods seek to reduce within-class variance while retaining between-class variance. Supervised discretization is shown to declutter classes in a manner that is superior to the state-of-the-art External Parameter Orthogonalization (EPO) by constructing a more parsimonious model with fewer parameters to optimize and is, consequently, less susceptible to overfitting and information loss. The comparison of supervised discretization and EPO is performed on three classification applications: X-ray fluorescence spectra of pine ash where the pine was grown in three distinct soil types, laser induced breakdown spectroscopy of colored artisanal glasses, and laser induced breakdown spectroscopy of exotic hardwood species.

Traumatic Finger Amputation in the U.S. Military.

INTRODUCTION: Finger amputations can lead to loss of work time and suboptimal function, particularly in the active duty military. There is a paucity of epidemiologic and outcome data for these injuries. The purposes of this study are to define key demographic data pertaining to transphalangeal finger amputations in the U.S. Military and to assess epidemiological data to define risk factors for medical readiness following finger injuries. MATERIALS AND METHODS: This was a retrospective review of the military electronic medical record of encounters between 2016 and 2019 with traumatic transphalangeal amputation ICD 10 codes S68.5 (thumb) and S68.6 (finger). Primary outcomes included median military occupational activity limitation length, ability to return to duty, and medical separation from the military. RESULTS: A total of 235 patients were included in the final dataset. 221 (94.0%) of these service members were able to return to full duty, although 14 (6.0%) underwent medical separation from the military because of their finger injuries. The median limited duty timeline was 6 weeks. Significant risk factors identified that led to increased rates of medical separation were the use of tobacco (odds ratio [OR] of 5.53, 95% CI 1.21-25.29), junior enlisted status (OR of 5.51, 95% CI 1.67-18.17), and thumb or index finger involvement (OR of 3.50, 95% CI 1.13-10.83). CONCLUSIONS: Within a physically high-demand population, traumatic finger amputation can limit duties and may lead to medical separation from service. Traumatic finger amputations are common and often require 6 weeks of restricted short-term disability, particularly in a tobacco-using, young, physically active cohort.

The Hopewell airburst event, 1699-1567 years ago (252-383 CE).

Meteorites, Fe and Si-rich microspherules, positive Ir and Pt anomalies, and burned charcoal-rich Hopewell habitation surfaces demonstrate that a cosmic airburst event occurred over the Ohio River valley during the late Holocene. A comet-shaped earthwork was constructed near the airburst epicenter. Twenty-nine radiocarbon ages establish that the event occurred between 252 and 383 CE, a time when 69 near-Earth comets were documented. While Hopewell people survived the catastrophic event, it likely contributed to their cultural decline. The Hopewell airburst event expands our understanding of the frequency and impact of cataclysmic cosmic events on complex human societies.

Assessing utility of handheld laser induced breakdown spectroscopy as a means of Dalbergia speciation.

Many species of Dalbergia are prized hardwoods, generally referred to as 'Rosewood,' and used in high-end products due to their distinctive hue and scent. Despite more than 58 species of Dalbergia being listed as endangered in Appendix 1 of The Convention on International Trade in Endangered Species of Fauna and Flora (CITES), the illegal logging and trade of this timber is ongoing. In this work, a handheld laser induced breakdown spectrometer (LIBS) was used to analyze seven Dalbergia species and two other exotic hardwood species to evaluate the ability of handheld LIBS for rapid classification of Dalbergia in the field. The KNN model of the classification presented 80% to 90% sensitivity for discriminating between Dalbergia species in the training set. PLS-DA models were based on a binary decision tree structure. Cumulatively, the PLS-DA decision tree model showed greater than 97% sensitivity and 99% selectivity for prediction of Dalbergia species included in the training set. The data presented in the following study are promising for the use of handheld LIBS devices and both KNN and PLS-DA models for applications in customs screenings at the port of entry of hard woods, among others.

Coaxial fiber-optic chemical-sensing excitation-emission matrix fluorometer.

Great reductions in the overall size and complexity of high throughput multichannel UV-visible fluorometers were achieved by coupling a compact optical fiber array to compact dispersive transmission optics. The coaxial configuration centers on the insertion of a silica/silica optical fiber into the hollow region of a UV-fused silica capillary waveguide. The outer core delivers the maximum power of the narrow wavelength region of the excitation spectrum created by coupling a xenon arc discharge lamp to a compact spectrometer. The molecular fluorescence resulting from the interaction of light emitted at the distal end of the hollow waveguide and the sample matrix is received and transmitted to a CCD via a compact dispersive grating-prism (grism) optical assembly. A linear array of the coaxial optical fibers permits a full excitation-emission matrix spectrum of the analyte matrix to be projected onto the face of the CCD. The in situ identification and monitoring of polycyclic aromatic hydrocarbons was carried out for the initial application testing for this prototype.

Photocatalytic degradation-excitation-emission matrix fluorescence for increasing the selectivity of polycyclic aromatic hydrocarbon analyses.

The application of photocatalysis enhancement to calibration of fluorescence excitation-emission matrixes (EEMs) with parallel factor (PARAFAC) analysis is described. In this study, three- and four-way PARAFAC analysis was employed to extract the fluorescent species' spectra from overlapping EEMs. Time-dependent photocatalysis degradation of the polycyclic aromatic hydrocarbons (PAHs) was employed to create an additional dimension for analysis. The consequent four-dimension degradation-EEM data cubes have greater selectivity for each PAH than do three-dimension EEM data cubes alone. On a scale of 0 to 1, with 0 being completely collinear spectra and 1 being orthogonal spectra, including the time-dependent measurements increased the selectivity an average of 21%, from 0.73 to 0.87.