Mid- and long-wave infrared point spectrometer (MLPS): a miniature space-borne science instrument.

The mid- and long-wave infrared point spectrometer (MLPS) is an infrared point spectrometer that utilizes unique technologies to meet the spectral coverage, spectral sampling, and field-of-view (FOV) requirements of many future space-borne missions in a small volume with modest power consumption. MLPS simultaneously acquires high resolution mid-wave infrared (∼2-4 µm) and long-wave infrared (∼5.5-11 µm) measurements from a single, integrated instrument. The broadband response of MLPS can measure spectroscopically resolved reflected and thermally emitted radiation from a wide range of targets and return compositional, mineralogic, and thermophysical science from a single data set. We have built a prototype MLPS and performed end-to-end testing under vacuum showing that the measured spectral response and the signal-to-noise ratio (SNR) for both the mid-wave infrared (MIR) and long-wave infrared (LIR) channels of MLPS agree with established instrument models.

An Ultra-Broadband High Efficiency Polarization Beam Splitter for High Spectral Resolution Polarimetric Imaging in the Near Infrared.

A broadband, high efficiency polarized beam splitter (PBS) metagrating based on integrated resonant units (IRUs) to enable simultaneous polarization analysis, spectral dispersion, and spatial imaging in the near infrared (NIR) is developed. A PBS metagrating with a diameter of 60 mm is the key technology component of the high-resolution multiple-species atmospheric profiler in the NIR (HiMAP-NIR), which is a spaceborne instrument concept crafted to be a core payload of NASA's new generation Earth System Observatory. HiMAP-NIR will enable the aerosol profiling in Earth's planetary boundary layer (from surface to2 km altitude) by simultaneously measuring four spatial-spectral-polarimetric images from 680 to 780 nm. Through detailed optimization of hybridized resonant modes in IRUs, the PBS metagrating shows a diffraction efficiency of 70% (or better) for all four linear-polarized incident light, and polarization contrasts between orthogonal states are 0.996 (or better) from 680 to 780 nm. It meets the stringent performance required by the HiMAP-NIR exploiting a new paradigm for the broad applications of metasurfaces.

A Comparison of Three Neural Network Approaches for Estimating Joint Angles and Moments from Inertial Measurement Units.

The application of artificial intelligence techniques to wearable sensor data may facilitate accurate analysis outside of controlled laboratory settings-the holy grail for gait clinicians and sports scientists looking to bridge the lab to field divide. Using these techniques, parameters that are difficult to directly measure in-the-wild, may be predicted using surrogate lower resolution inputs. One example is the prediction of joint kinematics and kinetics based on inputs from inertial measurement unit (IMU) sensors. Despite increased research, there is a paucity of information examining the most suitable artificial neural network (ANN) for predicting gait kinematics and kinetics from IMUs. This paper compares the performance of three commonly employed ANNs used to predict gait kinematics and kinetics: multilayer perceptron (MLP); long short-term memory (LSTM); and convolutional neural networks (CNN). Overall high correlations between ground truth and predicted kinematic and kinetic data were found across all investigated ANNs. However, the optimal ANN should be based on the prediction task and the intended use-case application. For the prediction of joint angles, CNNs appear favourable, however these ANNs do not show an advantage over an MLP network for the prediction of joint moments. If real-time joint angle and joint moment prediction is desirable an LSTM network should be utilised.

Multidimensional Ground Reaction Forces and Moments From Wearable Sensor Accelerations via Deep Learning.

OBJECTIVE: Monitoring athlete internal workload exposure, including prevention of catastrophic non-contact knee injuries, relies on the existence of a custom early-warning detection system. This system must be able to estimate accurate, reliable, and valid musculoskeletal joint loads, for sporting maneuvers in near real-time and during match play. However, current methods are constrained to laboratory instrumentation, are labor and cost intensive, and require highly trained specialist knowledge, thereby limiting their ecological validity and wider deployment. An informative next step towards this goal would be a new method to obtain ground kinetics in the field. METHODS: Here we show that kinematic data obtained from wearable sensor accelerometers, in lieu of embedded force platforms, can leverage recent supervised learning techniques to predict near real-time multidimensional ground reaction forces and moments (GRF/M). Competing convolutional neural network (CNN) deep learning models were trained using laboratory-derived stance phase GRF/M data and simulated sensor accelerations for running and sidestepping maneuvers derived from nearly half a million legacy motion trials. Then, predictions were made from each model driven by five sensor accelerations recorded during independent inter-laboratory data capture sessions. RESULTS: The proposed deep learning workbench achieved correlations to ground truth, by maximum discrete GRF component, of vertical Fz 0.97, anterior Fy 0.96 (both running), and lateral Fx 0.87 (sidestepping), with the strongest mean recorded across GRF components 0.89, and for GRM 0.65 (both sidestepping). CONCLUSION: These best-case correlations indicate the plausibility of the approach although the range of results was disappointing. The goal to accurately estimate near real-time on-field GRF/M will be improved by the lessons learned in this study. SIGNIFICANCE: Coaching, medical, and allied health staff could ultimately use this technology to monitor a range of joint loading indicators during game play, with the aim to minimize the occurrence of non-contact injuries in elite and community-level sports.

Patient-Reported Outcomes After Multiple-Revision ACL Reconstruction: Good but Not Great.

PURPOSE: To evaluate the patient-reported and objective functional outcomes of patients undergoing multiple-revision anterior cruciate ligament (ACL) reconstruction surgery. The secondary purpose was to determine failure rates and factors associated with failure, with a focus on posterior tibial slope. METHODS: All patients who underwent a repeat revision ACL reconstruction with a single surgeon over a 13-year period were identified. Chart data were obtained, including radiographic findings, operative details and findings, and postoperative examination findings. Failure was defined as subjective instability with evidence of graft incompetence on physical examination and MRI. Patients completed the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC-SKF) and Tegner Activity Level Scale. Patients who had outcomes scores completed a minimum of 2 years postoperatively were included. RESULTS: Fourteen patients were available for follow-up; 12 underwent secondary revision procedures, and 2 underwent tertiary revisions. Three patients (21%) had subsequent failure of the revision graft with mean time to failure of 27 months. Posterior tibial slope was significantly higher in the failures than in the nonfailures (13.3˚; 95% CI 10.1-16.6 versus 10.1˚; 95% CI 6.7-11.4; P = 0.049). Eleven patients completed outcomes measures at a mean of 42 months postoperatively (range 24-79 months). The mean Tegner activity score was 6.3 at follow-up, compared with 8.3 prior to the original ACL injury. The mean IKDC-SKF score was 70 at follow-up. CONCLUSION: Multiple revision ACL reconstruction surgery appears to have reasonable functional outcomes but is associated with a relatively high failure rate. Activity level following repeat revision surgery is diminished compared to the preinjury state, but most patients are able to return to recreational sports. LEVEL OF EVIDENCE: Therapeutic Study, Level IV.

On-field player workload exposure and knee injury risk monitoring via deep learning.

In sports analytics, an understanding of accurate on-field 3D knee joint moments (KJM) could provide an early warning system for athlete workload exposure and knee injury risk. Traditionally, this analysis has relied on captive laboratory force plates and associated downstream biomechanical modeling, and many researchers have approached the problem of portability by extrapolating models built on linear statistics. An alternative approach would be to capitalize on recent advances in deep learning. In this study, using the pre-trained CaffeNet convolutional neural network (CNN) model, multivariate regression of marker-based motion capture to 3D KJM for three sports-related movement types were compared. The strongest overall mean correlation to source modeling of 0.8895 was achieved over the initial 33% of stance phase for sidestepping. The accuracy of these mean predictions of the three critical KJM associated with anterior cruciate ligament (ACL) injury demonstrate the feasibility of on-field knee injury assessment using deep learning in lieu of laboratory embedded force plates. This multidisciplinary research approach significantly advances machine representation of real-world physical models with practical application for both community and professional level athletes.

Predicting athlete ground reaction forces and moments from motion capture.

An understanding of athlete ground reaction forces and moments (GRF/Ms) facilitates the biomechanist's downstream calculation of net joint forces and moments, and associated injury risk. Historically, force platforms used to collect kinetic data are housed within laboratory settings and are not suitable for field-based installation. Given that Newton's Second Law clearly describes the relationship between a body's mass, acceleration, and resultant force, is it possible that marker-based motion capture can represent these parameters sufficiently enough to estimate GRF/Ms, and thereby minimize our reliance on surface embedded force platforms? Specifically, can we successfully use partial least squares (PLS) regression to learn the relationship between motion capture and GRF/Ms data? In total, we analyzed 11 PLS methods and achieved average correlation coefficients of 0.9804 for GRFs and 0.9143 for GRMs. Our results demonstrate the feasibility of predicting accurate GRF/Ms from raw motion capture trajectories in real-time, overcoming what has been a significant barrier to non-invasive collection of such data. In applied biomechanics research, this outcome has the potential to revolutionize athlete performance enhancement and injury prevention. Graphical Abstract Using data science to model high-fidelity motion and force plate data frees biomechanists from the laboratory.

Imaging of Pericardial Diseases.

Given the widespread use of cross-sectional imaging modalities, specifically multidetector computed tomography and magnetic resonance, to evaluate thoracic disease, the pericardium is frequently imaged. Knowledge of the normal appearance and anatomical boundaries is vital for radiologists to avoid confusion with more sinister pathology. A variety of disorders and diseases of the pericardium can bring a patient to clinical attention from inflammatory conditions, resulting in pericarditis and pericardial effusion, to malignancy. This article discusses the anatomy and conditions that affect the pericardium, emphasizing the role imaging plays in diagnosis and management.

No need to abandon focused parathyroidectomy: a multicenter study of long-term outcome after surgery for primary hyperparathyroidism.

OBJECTIVE: The aim of this study was to investigate long-term outcomes after focused parathyroidectomy (FPTX) and open 4-gland parathyroid exploration (OPTX) for primary hyperparathyroidism (pHPT). BACKGROUND: Concerns about increased long-term recurrence rates after FPTX in conjunction with decreased operative times for OPTX have led some groups to abandon FPTX in favor of routine 4-gland exploration. METHODS: This is a multicenter retrospective cohort study of patients undergoing parathyroidectomy for pHPT from 1990 to 2013. The patient cohort was divided into 2 groups, FPTX and OPTX, based on intention-to-treat analysis. The primary outcome measure was the persistence of pHPT. Secondary outcome measures were differences in the long-term recurrence rate of persisting pHPT and surgical complications. RESULTS: A total of 4569 patients (3585 females) were included. The overall persistence and recurrence rates were 2.2% and 0.9%, respectively, after a median follow-up of 6.5 years. There were 2531 FPTX cases and 2038 OPTX cases. The initial persistence rate was higher for FPTX than for OPTX (2.7% vs 1.7%, P = 0.036); however, the long-term recurrence rate was not different (5-year 0.6% vs 0.4%, log-rank P = 0.08). Complications were more common in OPTX than in FPTX (7.6% vs 3.6%, P < 0.001). CONCLUSIONS: FPTX was associated with fewer operative complications and an equivalent rate of long-term recurrence than with OPTX. Although initial persistence rates were higher after FPTX than after OPTX, most were readily resolved with subsequent early reoperation. FPTX should not be abandoned in patients with positive preoperative localization.

Patient Outcomes and Predictors of Success After Revision Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Patient outcomes and predictors of success after revision anterior cruciate ligament (ACL) reconstruction are currently limited in the literature. Existing studies either have a small study size or are difficult to interpret because of the multiple surgeons involved in the care of the study sample. PURPOSE: To determine patient outcomes and predictors of success or failure after a single-stage revision ACL reconstruction by a single fellowship-trained senior surgeon at a single institution. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 78 patients who underwent revision ACL reconstruction by a single surgeon from 2010 to 2014 were contacted and available for follow-up. The mean time from revision procedure to follow-up was 52 months. Those patients who were able to participate in the study sent in a completed Tegner activity level scale, International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, and IKDC Current Health Assessment Form. The patients' medical records were also thoroughly reviewed. RESULTS: Five patients had subsequent failure after revision surgery. The median Tegner score was 6 at follow-up, and the mean subjective IKDC score was 72.5. There was no statistically significant difference in outcome scores when comparing revision graft type, body mass index, sex, need for bone grafting, and time from failure to revision. Patients with failures after primary ACL reconstruction secondary to a traumatic event were found to have statistically significantly higher IKDC scores (mean, 76.6) after revision when compared with nontraumatic failures (mean, 67.1), even when controlling for confounders (P < .017). CONCLUSION: Revision ACL reconstruction is effective in improving patient activity levels and satisfaction. However, the subjective IKDC results are quite variable and likely based on multiple factors. Patients with traumatic injuries contributing to graft failure after primary ACL reconstruction had a statistically significantly, although not clinically significant, higher IKDC score after revision surgery compared with nontraumatic failures. These data may be useful when counseling a patient on whether to pursue revision ACL reconstruction surgery.

Experimental active structural acoustic control of simply supported plates using a weighted sum of spatial gradients.

A limitation currently facing active structural acoustic control (ASAC) researchers is that an ideal minimization quantity for use in the control algorithms has not been developed. A novel parameter termed the "weighted sum of spatial gradients" (WSSG) was recently developed for use in ASAC and shown to effectively attenuate acoustic radiation from a vibrating flat simply supported plate in computer simulations. This paper extends this research from computer simulations and provides experimental test results. The results presented show that WSSG is a viable control quantity and provides better results than the volume velocity approach. The paper also investigates several of the challenges presented by the use of WSSG. These include determining a method to measure WSSG experimentally, an analysis of the influence of noise on WSSG control results and complications presented when degenerate modes exist. Results are shown and discussed for several experimental configurations.

Fine-needle aspiration of the thyroid: correlating suspicious cytology results with histological outcomes.

PURPOSE: Fine-needle aspiration cytology (FNAC) assists the diagnosis of thyroid malignancy. A 'suspicious for malignancy' on FNAC creates a management dilemma. The aims of this study were to investigate the malignancy rate for patients with suspicious cytology, and to describe a management approach for those with a suspicious result. METHODOLOGY: A retrospective review of prospectively collected data in an endocrine surgery database was undertaken. Patients undergoing thyroidectomy with preoperative FNAC from 1992 to 2012 were analysed. RESULTS: Preoperative FNAC was undertaken in 2,692 patients, and the FNAC result was 'suspicious for malignancy' in 94 (3.5 %) patients. Of these, 53 (56.4 %) were malignant, with the majority 44 (83.0 %) being papillary thyroid cancer. 48 patients went straight to total thyroidectomy, 40 patients had an initial diagnostic hemithyroidectomy, and 1 patient had a diagnostic isthmusectomy. 5 patients required reoperative total thyroidectomy as an initial procedure. Of the 94 suspicious cases, 55 were reported by an unknown, presumably non-expert, thyroid cytopathologist. 38 of these cases were available for review and re-reporting by an experienced cytopathologist. On review, 28 (73.7 %) were reclassified as cytologically malignant, and all of these were confirmed as malignant on subsequent histopathology. CONCLUSIONS: Suspicious cytology has a high risk of malignancy. Expert thyroid cytopathology can improve diagnostic accuracy and a preoperative malignant diagnosis should be pursued to enable one-stage surgery where possible.

Recurrent laryngeal nerve injury in thyroid surgery: a review.

Recurrent laryngeal nerve palsy (RLNP) is an important and potentially catastrophic complication of thyroid surgery. Permanent RLNP occurs in 0.3-3% of cases, with transient palsies in 5-8%. A literature review and analysis of recent data regarding RLNP in thyroid surgery was performed, with particular focus on the identification of high-risk patients, the role of intraoperative identification and dissection of the nerve, and the role of intraoperative neuromonitoring (IONM) and optimal perioperative nerve assessment. In conjunction with the review, data from the Monash University/Alfred Hospital Endocrine Surgery Unit between January 2007 and October 2011 were retrospectively analysed, including 3736 consecutive nerves at risk (NAR). The current literature and our data confirm that patients undergoing re-operative thyroid surgery and thyroid surgery for malignancies are at increased risk of RLNP. Intraoperative visualization and capsular dissection of the RLN remain the gold standard for intraoperative care during thyroid surgery for reducing RLNP risk. IONM should not be used as the sole mechanism for identifying and preserving the nerve, although it can be used to aid in the identification and dissection of the nerve, and may aid in nerve protection in high-risk cases including cancer surgery and re-operative surgery.

Microbolometer imaging spectrometer.

Newly developed, high-performance, long-wave- and mid-wave-IR Dyson spectrometers offer a compact, low-distortion, broadband, imaging spectrometer design. The design is further accentuated when coupled to microbolometer array technology. This novel coupling allows radiometric and spectral measurements of high-temperature targets. It also serves to be unique since it allows for the system to be aligned warm. This eliminates the need for cryogenic temperature cycling. Proof of concept results are shown for a spectrometer with a 7.5 to 12.0 µm spectral range and approximately 20 nm per spectral band (~200 bands). Results presented in this Letter show performance for remote hot targets (>200 °C) using an engineering grade spectrometer and IR commercial lens assembly.

Streamlining elective surgery care in a public hospital: the Alfred experience.

OBJECTIVE: To evaluate the effectiveness of redesigning and streamlining perioperative services. DESIGN: A before-and-after evaluation, with retrospective analysis of de-identified administrative data. SETTING: A major tertiary hospital, Melbourne, Australia. PARTICIPANTS: Patients undergoing elective surgery, February 2005 - February 2010. INTERVENTION: Implementing a process redesign to streamline clinical pathways for elective surgery, with a focus on the patient journey from referral to discharge, and establishing a separate, dedicated elective surgery facility. MAIN OUTCOME MEASURES: Numbers of patients waiting beyond national recommended waiting times for elective surgery; hospital-initiated postponement (HIP) rates for elective surgery; and lengths of stay (LOS), both combined and for specific diagnostic-related groups. RESULTS: The clinical process redesign resulted in a sustained downward trend in the number of elective surgery patients waiting longer than national recommended maximum waiting times. HIP rates were reduced to 1% in the dedicated elective surgery facility, and there was a significant reduction in the combined LOS, as well as the LOS for the most common surgical procedures (P < 0.001). CONCLUSIONS: Clinical process redesign of perioperative services and collocation of a separate elective surgery centre improved (i) timeliness of care for elective surgery patients and (ii) key indicators (LOS and HIP rates) for planned elective admissions.

Multispectral imaging of tissue absorption and scattering using spatial frequency domain imaging and a computed-tomography imaging spectrometer.

We present an approach for rapidly and quantitatively mapping tissue absorption and scattering spectra in a wide-field, noncontact imaging geometry by combining multifrequency spatial frequency domain imaging (SFDI) with a computed-tomography imaging spectrometer (CTIS). SFDI overcomes the need to spatially scan a source, and is based on the projection and analysis of periodic structured illumination patterns. CTIS provides a throughput advantage by simultaneously diffracting multiple spectral images onto a single CCD chip to gather spectra at every pixel of the image, thus providing spatial and spectral information in a single snapshot. The spatial-spectral data set was acquired 30 times faster than with our wavelength-scanning liquid crystal tunable filter camera, even though it is not yet optimized for speed. Here we demonstrate that the combined SFDI-CTIS is capable of rapid, multispectral imaging of tissue absorption and scattering in a noncontact, nonscanning platform. The combined system was validated for 36 wavelengths between 650-1000 nm in tissue simulating phantoms over a range of tissue-like absorption and scattering properties. The average percent error for the range of absorption coefficients (µa) was less than 10% from 650-800 nm, and less than 20% from 800-1000 nm. The average percent error in reduced scattering coefficients (µs') was less than 5% from 650-700 nm and less than 3% from 700-1000 nm. The SFDI-CTIS platform was applied to a mouse model of brain injury in order to demonstrate the utility of this approach in characterizing spatially and spectrally varying tissue optical properties.

Identification of common nail and skin disorders.

UNLABELLED: NARRATIVE REVIEW: The following review discusses the more common disorders of the perionychium and skin likely to be observed by the hand therapist. To assist the therapist in recognition of abnormalities, the anatomy, physiology, and basic function of the normal nail unit are described. Indications of when disorders of the nail, resulting from trauma, infections, and neoplasms, require referral to another practitioner are discussed. Characteristics of abnormal skin conditions are described with an emphasis on differentiating benign from malignant lesions. By knowing the suspicious characteristics of nail and skin disorders, the upper extremity therapist can positively impact the well-being of his or her patients through quick referral, leading to early diagnosis and treatment of potentially serious disease. LEVEL OF EVIDENCE: 5.

Snapshot hyperspectral imaging in ophthalmology.

Retinal imaging spectroscopy can provide functional maps using chromophore spectra. For example, oxygen saturation maps show ischemic areas from diabetes and venous occlusions. Obtaining retinal spatial-spectral data has been difficult due to saccades and long data acquisition times (>5 s). We present a snapshot imaging spectrometer with far-reaching applicability that acquires a complete spatial-spectral image cube in approximately 3 ms from 450 to 700 nm with 50 bands, eliminating motion artifacts and pixel misregistration. Current retinal spectral imaging approaches are incapable of true snapshot operation over a wide spectral range with a large number of spectral bands. Coupled to a fundus camera, the instrument returns true color retinal images for comparison to standard fundus images and for image validation while the patient is still dilated. Oxygen saturation maps were obtained with a three-wavelength algorithm: for healthy subjects arteries were approximately 95% and veins 30 to 35% less. The instrument is now undergoing clinical trials.