Simulated Inherent Optical Properties of Aquatic Particles using The Equivalent Algal Populations (EAP) model.

Paired measurements of phytoplankton absorption and backscatter, the inherent optical properties central to the interpretation of ocean colour remote sensing data, are notoriously rare. We present a dataset of Chlorophyll a (Chl a) -specific phytoplankton absorption, scatter and backscatter for 17 different phytoplankton groups, derived from first principles using measured in vivo pigment absorption and a well-validated semi-analytical coated sphere model which simulates the full suite of biophysically consistent phytoplankton optical properties. The optical properties of each simulated phytoplankton cell are integrated over an entire size distribution and are provided at high spectral resolution. The model code is additionally included to enable user access to the complete set of wavelength-dependent, angularly resolved volume scattering functions. This optically coherent dataset of hyperspectral optical properties for a set of globally significant phytoplankton groups has potential for use in algorithm development towards the optimal exploitation of the new age of hyperspectral satellite radiometry.

Viscoelastic-Induced Interlamellar Stromal Keratopathy (VISK) during Cataract Surgery in a Patient with a History of Laser in situ Keratomileusis.

A 47-year-old patient status post uncomplicated bilateral LASIK treatment presented with interlamellar stromal keratopathy induced by viscoelastic material during cataract surgery, decreasing her vision to CF (count fingers) postoperatively. After recognition, the viscoelastic material was removed by interface irrigation. The keratopathy improved by postoperative day 1 and resolved by 6 weeks with best-corrected visual acuity being 20/30. We conclude that viscoelastic-induced stromal keratopathy requires correct recognition in order to undertake appropriate management.

Osteoradionecrosis in osseous free flap reconstruction: Risk factors and treatment.

OBJECTIVE: To determine the rate and risk factors for osteoradionecrosis (ORN) in osseous free flaps after postoperative radiation therapy (PORT). To describe the treatment of free flap ORN. METHODS: Seventy-four patients undergoing osseous free flap reconstruction were analyzed. Thirty-eight completed PORT. Patients were followed for ≥6 months. RESULTS: The rate of ORN was 34% overall; 0% with 50 to 59.9 Gy; 8% with 60 Gy; 40% with 66 Gy; 56% with 70 to 74.4 Gy. Mean time to ORN was 13.1 months. 0/28 patients without PORT developed free flap osteonecrosis. Multivariate analysis found the only factor predicting ORN: PORT >60 Gy, which increased the risk 21-fold. Treatment included PENTACLO, hyperbaric oxygen, and surgical debridement with 75% within 2 years. CONCLUSION: PORT >60 Gy is significantly associated with free flap ORN. As the dose of adjuvant RT increases beyond 60 Gy, the risk of ORN in free flaps rises. Consideration should be given to lower PORT doses or delaying free flap reconstruction when feasible.

Prophylactic antibiotics in head and neck free flap surgery: A novel protocol put to the test.

OBJECTIVE: Recent evidence supports the use of ampicillin-sulbactam as a favored choice for antibiotic prophylaxis following head and neck free flap reconstructive surgery. However, there is a paucity of evidence guiding the optimal duration of antibiotic prophylaxis. The aim of this study is to compare the infection rates of short courses of ampicillin-sulbactam versus extended courses of various antibiotics in head and neck free flap reconstructive surgery. METHODS: This is a retrospective cohort study conducted from 2012 to 2017 at a tertiary academic center on 266 consecutive patients undergoing head and neck surgery with free flap reconstruction. The primary outcome measure was the rate of any infection within 30 days of surgery. RESULTS: There were 149 patients who received antibiotic prophylaxis for an extended duration of at least seven days. 117 patients received a short course of antibiotics defined as 24 h for non-radiated patients and 72 h for radiated patients. Postoperative infections occurred in 45.9% of patients, of which 92.6% occurred at surgical sites. There was no significant difference in terms of postoperative infection rate between patients receiving an extended duration of antibiotics versus a short duration (p = 0.80). This held true for subgroups of surgical site infections (p = 0.38) and distant infections (p = 0.59 for pneumonia and p = 0.76 for UTI). Risk factors for infections were identified as hypothyroidism (p = 0.047) and clean contaminated wound classification (p = 0.0002). CONCLUSION: Shorter duration of ampicillin-sulbactam prophylaxis in free flap reconstruction of head and neck defects does not negatively affect postoperative infection rates. LEVEL OF EVIDENCE: Level 2b.

Discharge Delay in Head and Neck Free Flap Surgery: Risk Factors and Strategies to Minimize Hospital Days.

OBJECTIVE: Length of stay (LOS) includes time medically necessary in the hospital and time waiting for discharge (DC) afterward. This DC delay is determined in head and neck free flap patients. Reasons for and factors leading to DC delay, as well as associated adverse outcomes, are elucidated. METHODS: Retrospective chart review was performed for all head and neck free flap surgeries from 2012 to 2017. Data including demographics, comorbidities, and perioperative factors were collected. Regression analyses were performed to identify factors associated with DC delay. RESULTS: In total, 264 patients were included. Mean total LOS was 13.1 days. DC delay occurred in 65% of patients with a mean of 4.8 days. Factors associated with DC delay on univariate analysis included Medicaid/self-pay insurance, DC to a facility, and not having children ( P < .05). Multivariate analysis showed prolonged medically necessary LOS and surgery on a Monday/Friday ( P < .05) were associated with DC delay. Top reasons for DC delay included case management shortages, rejection by facility, and awaiting supplies. Eleven percent experienced complications during the DC delay. DISCUSSION: DC delay can add days and complications to the LOS. Prevention begins preoperatively with DC planning involving the patient's closest family. Understanding limitations of the patient's insurance may help plan DC destination. Optimizing hospital resources when available should be a focus. IMPLICATIONS FOR PRACTICE: Head and neck free flap patients require a team of teams unified in optimizing quality of care. DC delay is a novel quality metric reflecting the team's overall performance. Through strategic DC planning and capitalizing on available resources, DC delay can be minimized.

Satellite Ocean Colour: Current Status and Future Perspective.

Spectrally resolved water-leaving radiances (ocean colour) and inferred chlorophyll concentration are key to studying phytoplankton dynamics at seasonal and interannual scales, for a better understanding of the role of phytoplankton in marine biogeochemistry; the global carbon cycle; and the response of marine ecosystems to climate variability, change and feedback processes. Ocean colour data also have a critical role in operational observation systems monitoring coastal eutrophication, harmful algal blooms, and sediment plumes. The contiguous ocean-colour record reached 21 years in 2018; however, it is comprised of a number of one-off missions such that creating a consistent time-series of ocean-colour data requires merging of the individual sensors (including MERIS, Aqua-MODIS, SeaWiFS, VIIRS, and OLCI) with differing sensor characteristics, without introducing artefacts. By contrast, the next decade will see consistent observations from operational ocean colour series with sensors of similar design and with a replacement strategy. Also, by 2029 the record will start to be of sufficient duration to discriminate climate change impacts from natural variability, at least in some regions. This paper describes the current status and future prospects in the field of ocean colour focusing on large to medium resolution observations of oceans and coastal seas. It reviews the user requirements in terms of products and uncertainty characteristics and then describes features of current and future satellite ocean-colour sensors, both operational and innovative. The key role of in situ validation and calibration is highlighted as are ground segments that process the data received from the ocean-colour sensors and deliver analysis-ready products to end-users. Example applications of the ocean-colour data are presented, focusing on the climate data record and operational applications including water quality and assimilation into numerical models. Current capacity building and training activities pertinent to ocean colour are described and finally a summary of future perspectives is provided.

Calibration of an in-water multi-excitation fluorometer for the measurement of phytoplankton chlorophyll-a fluorescence quantum yield.

A multi-excitation fluorometer (MFL, JFE Advantech Co., Ltd.), originally designed to discriminate between phytoplankton species present within a population, has been redirected for use in fluorescence quantum yield (FQY) determination. While this calibration for apparent FQY requires no modification of the MFL, it is necessary to have an independent measurement of the spectral absorption coefficient of the subject fluid. Two different approaches to calibration were implemented. The primary method made use of reference fluorescent dye solutions of known quantum yield. The second method made use of acrylic fluorescent plaques and films. The two methods yielded consistent results, except in the 570 and 590 nm LED channels of the MFL. Application of the MFL in FQY determination is illustrated with an in situ Southern Ocean sample.

Antibiotics, steroids, and combination therapy in chronic rhinosinusitis without nasal polyps in adults.

Despite a lack of robust data regarding their efficacy, oral antibiotics and steroids remain two of the most common treatments for chronic rhinosinusitis without nasal polyps (CRSsNP). We sought to objectively compare the efficacy of antibiotics and steroids, independently and in combination, for the initial treatment of CRSsNP. To that end, we conducted a retrospective chart review of 100 patients-51 men and 49 women, age 20 to 85 years (mean: 50)-who were treated for CRSsNP from January 2010 through January 2015. Of this group, 17 patients were treated with an antibiotic only, 28 with a steroid only, and 55 with both agents. All patients underwent computed tomography (CT) before and after treatment, and we compared the three groups' pre- and post-treatment Lund-Mackay CT scores, symptom scores, and rates of surgery. The average time between the pre- and post-treatment visits was 4.4 weeks. The mean Lund-Mackay CT score for the entire study population was significantly lower after treatment than at baseline (6.3 vs. 9.1; p < 0.001); however, there were no significant differences among the three groups in either pre- or post-treatment scores. Symptom scores were significantly better in the combination therapy group than in the two monotherapy groups (p < 0.001). In all, 40 of the 100 patients underwent surgery; the difference in surgery rates among the three groups was not statistically significant (p = 0.884). Surgery was performed on 9 of the 52 (17.3%) patients who either were followed for at least 1 year or who had had surgery within the first year postoperatively; again, there were no significant differences among the three groups (p = 0.578). We conclude that although the Lund-Mackay CT scores decreased significantly in the antibiotic, steroid, and combination therapy groups, no one regimen was superior to any other for treating CRSsNP in our study.

Improving quality outcomes in head and neck free flap surgery with the use of a physician inpatient coordinator.

OBJECTIVES/HYPOTHESIS: Head and neck free flap patients require complex postoperative care. The quality of care for these patients often depends on their management from the time they leave the operating room. The purpose of this study was to investigate the impact of a postoperative inpatient coordinator (IC) for head and free flap patients on quality outcomes: length of stay (LOS), 30-day unplanned return to the emergency department (30dRED), 30-day unplanned readmissions (30dUR), and complication rates. STUDY DESIGN: Retrospective cohort study. METHODS: One hundred eighty-eight consecutive patients who underwent head and neck free flap surgery between January 2012 and January 2016 were reviewed using a prospective database. Patients had an IC for their entire hospitalization (group 1) or for less than their entire hospitalization (group 2). Logistic regression analysis was performed to identify risk factors for quality outcomes. RESULTS: Mean LOS was 13.8 days and 17.3 days in groups 1 and 2, respectively (P = .002). The 30dRED rate was 12% and 22%, respectively (P = .04). Group 2 had an increased LOS by 4.1 days (P = .001) and a 2.4 fold increased 30dRED (P = .03). 30dUR and complications were not influenced by the IC (P > .05). CONCLUSIONS: An IC may help decrease LOS and 30dRED in head and neck free flap patients. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:336-342, 2018.

Understanding the contribution of phytoplankton phase functions to uncertainties in the water colour signal.

The accurate description of a water body's volume scattering function (VSF), and hence its phase functions, is critical to the determination of the constituent inherent optical properties (IOPs), the associated spectral water-leaving reflectance, and consequently the retrieval of phytoplankton functional type (PFT) information. The equivalent algal populations (EAP) model has previously been evaluated for phytoplankton-dominated waters, and offers the ability to provide phytoplankton population-specific phase functions, unveiling a new opportunity to further understanding of the causality of the PFT signal. This study presents and evaluates the wavelength dependent, spectrally variable EAP particle phase functions and the subsequent effects on water-leaving reflectance. Comparisons are made with frequently used phase function approximations e.g. the Fournier Forand formulation, as well as with phase functions inferred from measured VSFs in coastal waters. Relative differences in shape and magnitude are quantified. Reflectance modelled with the EAP phase functions is then compared against measured reflectance data from phytoplankton-dominated waters. Further examples of modelled phytoplankton-dominated waters are discussed with reference to choice of phase function for two PFTs (eukaryote and prokaryote) across a range of biomass. Finally a demonstration of the sensitivity of reflectance due to the choice of phase function is presented. The EAP model phase functions account for both spectral and angular variability in phytoplankton backscattering i.e. they display variability which is both spectral and shape-related. It is concluded that phase functions modelled in this way are necessary for investigating the effects of assemblage variability on the ocean colour signal, and should be considered for model closure even in relatively low scattering conditions where phytoplankton dominate the IOPs.

Biophysical modelling of phytoplankton communities from first principles using two-layered spheres: Equivalent Algal Populations (EAP) model: erratum.

We regret that the Rrs spectra shown for the EAP modelled high biomass validation in Fig. 7 [Opt. Express, 22, 16745 (2014)] are incorrect. They are corrected here. The closest match of modelled to measured effective diameter is for a generalised 16 µm dinoflagellate population and not a 12 µm one as previously stated. These corrections do not affect the discussion or the conclusions of the paper.

Head and Neck Ultrasound Education-A Multimodal Educational Approach in the Predoctoral Setting: A Pilot Study.

OBJECTIVES: With the increased implementation of ultrasound in medical education, it is important to continually improve instructional methods. In this study, we demonstrate that by augmenting the traditional methods of instructor demonstration and student practice on a healthy volunteer with additional modalities, such as didactic presentation, simulated pathologic cases, and simulated procedures, students gain a more comprehensive understanding of and confidence in ultrasound technique and pathology. METHODS: A multimodal curriculum was developed and applied to head and neck ultrasound sessions of our institution's Ultrasound Symposium. Participants were asked to fill out surveys rating each instructional modality as well as preinstructional and postinstructional confidence. The survey results were divided into a group of first- and second-year medical students who had previous ultrasound training and a group of third- and fourth-year students who were ultrasound "naïve." RESULTS: The survey showed that the first- and second-year student group (n = 8) had an average preinstructional confidence of 4.14/10 compared to 1.44/10 in the third- and fourth-year student group (n = 9) (P = .003). Following the instructional sessions, the students' confidence increased respectively to 8.14/10 and 7.78/10 (P= .53), showing a 4.00 (96%) increase in the first- and second-year group and a 6.34 (440%) increase in the third- and fourth-year group. The combined results of all student teaching modality ratings showed that instructor demonstration was rated the highest (9.47) and computerized simulation lowest (8.25). CONCLUSIONS: Overall, our study shows that multimodal ultrasound instruction was beneficial in increasing both ultrasound-trained and ultrasound-naïve medical students' confidence in head and neck ultrasound.

A Cost-effective, Gelatin-Based Phantom Model for Learning Ultrasound-Guided Fine-Needle Aspiration Procedures of the Head and Neck.

The rise in popularity of ultrasound imaging has seen a corresponding increase in demand for effective training tools such as phantom models. They are especially useful for teaching and practice of invasive procedures, such as fine-needle aspiration of lesions of the head and neck. We have created 2 gelatin models out of inexpensive, commonly available materials that can be used in sequence to learn head and neck fine-needle aspiration. Fundamental skills can be learned first on the flat, rectangular model, whereas the second, cylindrical model more closely represents human anatomy and can be used to develop more advanced technique.

Harmful algal blooms and climate change: Learning from the past and present to forecast the future.

Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, light, ocean acidification, precipitation-induced nutrient inputs, and grazing, but absence of fundamental knowledge of the mechanisms driving harmful algal blooms frustrates most hope of forecasting their future prevalence. Summarized here is the consensus of a recent workshop held to address what currently is known and not known about the environmental conditions that favor initiation and maintenance of harmful algal blooms. There is expectation that harmful algal bloom (HAB) geographical domains should expand in some cases, as will seasonal windows of opportunity for harmful algal blooms at higher latitudes. Nonetheless there is only basic information to speculate upon which regions or habitats HAB species may be the most resilient or susceptible. Moreover, current research strategies are not well suited to inform these fundamental linkages. There is a critical absence of tenable hypotheses for how climate pressures mechanistically affect HAB species, and the lack of uniform experimental protocols limits the quantitative cross-investigation comparisons essential to advancement. A HAB "best practices" manual would help foster more uniform research strategies and protocols, and selection of a small target list of model HAB species or isolates for study would greatly promote the accumulation of knowledge. Despite the need to focus on keystone species, more studies need to address strain variability within species, their responses under multifactorial conditions, and the retrospective analyses of long-term plankton and cyst core data; research topics that are departures from the norm. Examples of some fundamental unknowns include how larger and more frequent extreme weather events may break down natural biogeographic barriers, how stratification may enhance or diminish HAB events, how trace nutrients (metals, vitamins) influence cell toxicity, and how grazing pressures may leverage, or mitigate HAB development. There is an absence of high quality time-series data in most regions currently experiencing HAB outbreaks, and little if any data from regions expected to develop HAB events in the future. A subset of observer sites is recommended to help develop stronger linkages among global, national, and regional climate change and HAB observation programs, providing fundamental datasets for investigating global changes in the prevalence of harmful algal blooms. Forecasting changes in HAB patterns over the next few decades will depend critically upon considering harmful algal blooms within the competitive context of plankton communities, and linking these insights to ecosystem, oceanographic and climate models. From a broader perspective, the nexus of HAB science and the social sciences of harmful algal blooms is inadequate and prevents quantitative assessment of impacts of future HAB changes on human well-being. These and other fundamental changes in HAB research will be necessary if HAB science is to obtain compelling evidence that climate change has caused alterations in HAB distributions, prevalence or character, and to develop the theoretical, experimental, and empirical evidence explaining the mechanisms underpinning these ecological shifts.

Sensitivity in reflectance attributed to phytoplankton cell size: forward and inverse modelling approaches.

Synoptic scale knowledge of the size structure of phytoplankton communities can offer insight in to primary ecosystem diversity and biogeochemical variability from operational to the decadal scales. Accordingly, obtaining estimates of size and other phytoplankton functional type descriptors within known confidence limits from remotely sensed data has become a major objective to extend the use of ocean colour data beyond chlorophyll a retrievals. Here, a new forward and inverse modelling structure is proposed to determine information about the cell size of phytoplankton communities using Standard size distributions of two layered spheres to derive a full suite of algal inherent optical properties for a coupled radiative transfer model. This new capability allows explicit quantification of the remote sensing reflectance signal attributable to changes in phytoplankton cell size. Inversion of this model reveals regions within the parameter space where ambiguity may limit potential of inversion algorithms. Validation of the algorithm within the Benguela upwelling system using independent data shows promise for ecosystem applications and further investigation of the interaction between phytoplankton functional types and optical signals. The results here suggest that the utility of assemblage related signals in spectral reflectance is highly sensitive to algal biomass, the presence of other absorbing and scattering constituents and the resultant constituent-specific inherent optical property budget. As such, optimal methods for determining phytoplankton size from (in situ or satellite) ocean colour data will likely rely on appropriately spectrally dense and optimised sensors, well characterised measurement errors including those from atmospheric correction, and an ability to appropriately limit ambiguity within the context of regional inherent optical properties.