Influence of NaCl concentration on the optical scattering properties of water-based aerosols.

We present the characterization of several atmospheric aerosol analogs in a tabletop chamber and an analysis of how the concentration of NaCl present in these aerosols influences their bulk optical properties. Atmospheric aerosols (e.g., fog and haze) degrade optical signal via light-aerosol interactions causing scattering and absorption, which can be described by Mie theory. This attenuation is a function of the size distribution and number concentration of droplets in the light path. These properties are influenced by ambient conditions and the droplet's composition, as described by Köhler theory. It is therefore possible to tune the wavelength-dependent bulk optical properties of an aerosol by controlling droplet composition. We present experimentation wherein we generated multiple microphysically and optically distinct atmospheric aerosol analogs using salt water solutions with varying concentrations of NaCl. The results demonstrate that changing the NaCl concentration has a clear and predictable impact on the microphysical and optical properties of the aerosol.

A Novel Do-It-Yourself Approach to Simulating Minimally Invasive Laparoscopic Surgery.

In 2008, the American Board of Surgery required residents to pass a laparoscopic fundamentals examination to sit for the boards. As such, minimally invasive surgery became the newest addition as a requisite skill for surgical trainees. To assist in preparing trainees for future surgery, simulation devices have been integrated into training programs to develop proficiency with laparoscopic and arthroscopic techniques. While effective, one of the biggest obstacles to accessing these devices is the thousands of dollars required for the equipment. Many commercial and do-it-yourself (DIY) iterations of low-cost, portable, laparoscopic simulators have been described to address this. While the price point ranges from 300 to 400 dollars, these DIY simulators primarily utilize webcams, iPhones, and tablet cameras in a fixed position. This presents an inherent limitation in the simulator's accuracy as current laparoscopy surgery utilizes camera motion. This study presents a novel DIY simulator that portrays a more realistic view of the operative field using camera motion and positioning, costing approximately 200 dollars. This proposed simulator uses a Universal Serial Bus (USB) endoscope with interchangeable side mirrors. We inserted an endoscope with built-in light-emitting diode (LED) lights into a seamless stainless tube for the laparoscope and attached it to a computer for configuration. To simulate the abdominal cavity, holes were drilled into a ½ torso hollow mannequin at the standard port locations for laparoscopic cholecystectomy, and rubber grommets were inserted into the drilled holes. Trocars were constructed using cross-linked polyethylene (PEX) tubing and #8 rubber stoppers. By creating a more affordable and easily constructed model, acquiring laparoscopic skills is more accessible. Simulators are becoming an essential part of medical training. Affordable simulators like ours allow trainees to develop their laparoscopic skill set at their own pace and convenience. More research into this can potentially lead to increased exposure to more accurate simulators and facilitate more accessible training for performing minimally invasive surgery in any surgical specialty.

Increased range and contrast in fog with circularly polarized imaging.

Fogs, low lying clouds, and other highly scattering environments pose a challenge for many commercial and national security sensing systems. Current autonomous systems rely on optical sensors for navigation whose performance is degraded by highly scattering environments. In our previous simulation work, we have shown that polarized light can penetrate through a scattering environment such as fog. We have demonstrated that circularly polarized light maintains its initial polarization state better than linearly polarized light, even through large numbers of scattering events and thus ranges. This has recently been experimentally verified by other researchers. In this work, we present the design, construction, and testing of active polarization imagers at short-wave infrared and visible wavelengths. We explore multiple polarimetric configurations for the imagers, focusing on linear and circular polarization states. The polarized imagers were tested at the Sandia National Laboratories Fog Chamber under realistic fog conditions. We show that active circular polarization imagers can increase range and contrast in fog better than linear polarization imagers. We show that when imaging typical road sign and safety retro-reflective films, circularly polarized imaging has enhanced contrast throughout most fog densities/ranges compared to linearly polarized imaging and can penetrate over 15 to 25 m into the fog beyond the range limit of linearly polarized imaging, with a strong dependence on the interaction of the polarization state with the target materials.

Phylogenomic analysis of the bowfin (Amia calva) reveals unrecognized species diversity in a living fossil lineage.

The Bowfin (Amia calva), as currently recognized, represents the sole living member of the family Amiidae, which dates back to approximately 150 Ma. Prior to 1896, 13 species of extant Bowfins had been described, but these were all placed into a single species with no rationale or analysis given. This situation has persisted until the present day, with little attention given to re-evaluation of those previously described nominal forms. Here, we present a phylogenomic analysis based on over 21,000 single nucleotide polymorphisms (SNPs) from 94 individuals that unambiguously demonstrates the presence of at least two independent evolutionary lineages within extant Amia populations that merit species-level standing, as well as the possibility of two more. These findings not only expand the recognizable species diversity in an iconic, ancient lineage, but also demonstrate the utility of such methods in addressing previously intractable questions of molecular systematics and phylogeography in slowly evolving groups of ancient fishes.

Evaluating changes in growth and pigmentation of Cladosporium cladosporioides and Paecilomyces variotii in response to gamma and ultraviolet irradiation.

Melanin-containing fungi (black molds) have the capacity to thrive under extreme environmental conditions such as the elevated radiation levels inside the former Chernobyl reactors. These fungi have been hypothesized to grow toward and use gamma radiation as an energy source, but the literature does not clearly address which energies of the electromagnetic spectrum, if any, positively affect fungal growth. The goal of this work was to characterize the response of non-melanized and melanized fungi to two distinct electromagnetic wavelengths, i.e., ultraviolet (UV) and gamma ray, keeping absorption and other potentially confounding variables constant. Exposure to UV or gamma radiation induced significant changes in fungi pigmentation, but not growth rate of Cladosporium cladosporioides and Paecilomyces variotii. Specifically, increased pigmentation of both fungi was observed in samples exposed to UV, while decreased pigmentation was observed for gamma-irradiated samples. These results provide new insights into the role of electromagnetic energies on growth of fungi and provide an impetus to examine additional energies and types of radiation to develop a fundamental understanding of this phenomenon.

Incorporating the effects of objects in an approximate model of light transport in scattering media.

A computationally efficient radiative transport model is presented that predicts a camera measurement and accounts for the light reflected and blocked by an object in a scattering medium. The model is in good agreement with experimental data acquired at the Sandia National Laboratory Fog Chamber Facility (SNLFC). The model is applicable in computational imaging to detect, localize, and image objects hidden in scattering media. Here, a statistical approach was implemented to study object detection limits in fog.

Light transport with weak angular dependence in fog.

Random scattering and absorption of light by tiny particles in aerosols, like fog, reduce situational awareness and cause unacceptable down-time for critical systems or operations. Computationally efficient light transport models are desired for computational imaging to improve remote sensing capabilities in degraded optical environments. To this end, we have developed a model based on a weak angular dependence approximation to the Boltzmann or radiative transfer equation that appears to be applicable in both the moderate and highly scattering regimes, thereby covering the applicability domain of both the small angle and diffusion approximations. An analytic solution was derived and validated using experimental data acquired at the Sandia National Laboratory Fog Chamber facility. The evolution of the fog particle density and size distribution were measured and used to determine macroscopic absorption and scattering properties using Mie theory. A three-band (0.532, 1.55, and 9.68 µm) transmissometer with lock-in amplifiers enabled changes in fog density of over an order of magnitude to be measured due to the increased transmission at higher wavelengths, covering both the moderate and highly scattering regimes. The meteorological optical range parameter is shown to be about 0.6 times the transport mean free path length, suggesting an improved physical interpretation of this parameter.

Urinary stone disease prevalence and associations in cystic fibrosis.

Cystic fibrosis (CF) may predispose patients to urinary stone disease (USD), but reported prevalence of USD in patients with CF in previous small studies is variable. To date, analysis of risk factors for USD within the CF population has been limited. We studied 29,396 patients in the Cystic Fibrosis Foundation Patient Registry to calculate age and sex-stratified prevalence of USD. For adult patients, we examined age and multivariable-adjusted cross-sectional associations between demographic and clinical factors, CFTR mutation class, and prevalent USD. Prevalence of USD was 0.4% (95% CI 0.3-0.5%) under age 18 years, 3.1% (2.7-3.6%) at 18-24 years, 6.4% (5.8-7.1%) at 25-34 years, 7.5% (6.5-8.5%) at 35-44 years, and 6.7% (5.8-7.8%) at 45 years and older. Prevalence for women was higher than men at younger (< 45 years) but not older ages (P value for interaction < 0.0005). Multivariable odds of prevalent USD were significantly increased for severe CFTR mutations, OR 1.53 (1.14-2.06), diabetes, OR 1.24 (1.03-1.50), hypertension, OR 1.58 (1.29-1.93), and chronic macrolide therapy, OR 1.27 (1.07-1.52). BMI was not associated with USD. USD prevalence in CF is similar to that in the general population. With the exception of BMI, known risk factors for USD in the general population also appear to be important for patients with CF. We identified several novel associations in CF patients, including greater prevalence of USD in individuals with severe CFTR mutations and among young women.

Estimates of gene flow and dispersal in wild riverine Brook Trout (Salvelinus fontinalis) populations reveal ongoing migration and introgression from stocked fish.

As anthropogenic impacts accelerate changes to landscapes across the globe, understanding how genetic population structure is influenced by habitat features and dispersal is key to preserving evolutionary potential at the species level. Furthermore, knowledge of these interactions is essential to identifying potential constraints on local adaptation and for the development of effective management strategies. We examined these issues in Brook Trout (Salvelinus fontinalis) populations residing in the Upper Hudson River watershed of New York State by investigating the spatial genetic structure of over 350 fish collected from 14 different sampling locations encompassing three river systems. Population genetic analyses of microsatellite data suggest that fish in the area exhibit varying degrees of introgression from nearby State-directed supplementation activities. Levels of introgression in these populations correlate with water-way distance to stocking sites, although genetic population structure at the level of individual tributaries as well as their larger, parent river systems is also detectable and is dictated by migration and influenced by habitat connectivity. These findings represent a significant contribution to the current literature surrounding Brook Trout migration and dispersal, especially as it relates to larger interconnected systems. This work also suggests that stocking activities may have far-reaching consequences that are not directly limited to the immediate area where stocking occurs. The framework and data presented here may aid in the development of other local aquatic species-focused conservation plans that incorporate molecular tools to answer complex questions regarding diversity mapping, and genetically important conservation units.

Genetic variation and biogeography of the spotted gar Lepisosteus oculatus from core and peripheral populations.

The spotted gar (Lepisosteus oculatus) shows a disjunct natural distribution, with a core population extending from the central Mississippi River Basin to the U.S. gulf coast and a peripheral population in the southern Great Lakes Basin. Despite significant conservation concerns for this species in the Great Lakes watersheds where it occurs, few genetic examinations and comparisons of these populations have been performed. We investigated inter- and intrapopulational variation in several mitochondrial genetic markers (cytochrome oxidase subunit I, COI; cytochrome oxidase subunit II, COII; and 16S rRNA, 16S) from spotted gars taken from core and peripheral populations. Genetic diversity was highest in the Mississippi River Basin and lowest in the Great Lakes Basin, while the Nueces River Basin (Texas) population showed the greatest level of divergence from other populations. Average genetic distance among core and peripheral populations was over an order of magnitude less than that seen between L. oculatus and its sister species, the Florida gar (L. platyrhincus), although a significant correlation was found between genetic and geographical distance in L. oculatus. Genetic divergence in spotted gars is likely to be related to a combination of geographic isolation and founder effects associated with recent colonization following glacial retreat. Despite its apparent lack of significant genetic differentiation or haplotype diversity, the Great Lakes population of spotted gars has previously been shown to be a unique component of the species, and additional studies are needed to determine the genetic mechanisms underlying regional adaptations as well as potential morphological differentiation among spotted gar populations.

Nonpolar InGaN/GaN Core-Shell Single Nanowire Lasers.

We report lasing from nonpolar p-i-n InGaN/GaN multi-quantum well core-shell single-nanowire lasers by optical pumping at room temperature. The nanowire lasers were fabricated using a hybrid approach consisting of a top-down two-step etch process followed by a bottom-up regrowth process, enabling precise geometrical control and high material gain and optical confinement. The modal gain spectra and the gain curves of the core-shell nanowire lasers were measured using micro-photoluminescence and analyzed using the Hakki-Paoli method. Significantly lower lasing thresholds due to high optical gain were measured compared to previously reported semipolar InGaN/GaN core-shell nanowires, despite significantly shorter cavity lengths and reduced active region volume. Mode simulations show that due to the core-shell architecture, annular-shaped modes have higher optical confinement than solid transverse modes. The results show the viability of this p-i-n nonpolar core-shell nanowire architecture, previously investigated for next-generation light-emitting diodes, as low-threshold, coherent UV-visible nanoscale light emitters, and open a route toward monolithic, integrable, electrically injected single-nanowire lasers operating at room temperature.

Effects of collection geometry variations on linear and circular polarization persistence in both isotropic-scattering and forward-scattering environments.

We present simulation and experimental results showing circular polarization is more tolerant of optical collection geometry (field of view and collection area) variations than linear polarization for forward-scattering environments. Circular polarization also persists superiorly in the forward-scattering environment compared to linear polarization by maintaining its degree of polarization better through increasing optical thicknesses. In contrast, both linear and circular polarizations are susceptible to collection geometry variations for isotropic-scattering (Rayleigh regime) environments, and linear polarization maintains a small advantage in polarization persistence. Simulations and measurements are presented for laboratory-based environments of polystyrene microspheres in water. Particle diameters were 0.0824 µm (for isotropic-scattering) and 1.925 µm (for forward-scattering) with an illumination wavelength of 543.5 nm.

The changing face of obstetric fistula surgery in Ethiopia.

OBJECTIVE: To examine the incidence and type of obstetric fistula presenting to Hamlin Fistula Ethiopia over a 4-year period. STUDY DESIGN: This is a 4-year retrospective survey of obstetric fistula treated at three Hamlin Fistula Hospitals in Ethiopia, where approximately half of all women in the country are treated. The operation logbook was reviewed to identify all new cases of obstetric fistula presenting from 2011 to 2015. New cases of urinary fistula were classified by fistula type (high or low), age, and parity of the woman. RESULTS: In total, 2,593 new cases of urinary fistulae were identified in the study period. The number of new cases fell by 20% per year over the 4 years (P<0.001). A total of 1,845 cases (71.1%) were low (ischemic) fistulae, and 804 cases (43.6%) of these had an extreme form of low circumferential fistula. A total of 638 (24.6%) women had a high bladder fistula, which predominantly occurs following surgery, specifically cesarean section or emergency hysterectomy, and 110 (4.2%) women had a ureteric fistula. The incidence of high fistulae increased over the study period from 26.9% to 36.2% (P<0.001). A greater proportion of multiparous women had a high bladder fistula (70.3%) compared with primigravid women (29.7%) (P<0.001). Conversely, a greater proportion of primiparous women experienced a low circumferential fistulae (68.6%) compared with multiparous women (31.4%) (P<0.001). CONCLUSION: There appears to be a decline in the number of Ethiopian women being treated for new obstetric urinary fistulae. However, the type of fistula being presented for treatment is changing, with a rise in high fistulae that very likely occurred following cesarean section and a decline in the classic low fistulae that arise following obstructed childbirth.

Prevalence of obstetric fistula and symptomatic pelvic organ prolapse in rural Ethiopia.

INTRODUCTION AND OBJECTIVE: Little is known about the extent to which women in low- and middle-income countries suffer with urological and urogynaecological complications of childbirth. This study measured the prevalence of obstetric fistula and symptomatic pelvic organ prolapse (POP) in east and north Ethiopia. METHODS: We randomly selected 23,023 women of reproductive age (15-49 years) from 113 villages in East Harraghe, South Gondar and West Gojjam, Ethiopia. Trained local health workers administered a validated face-to-face survey and a team of researchers verified data by readministering a random selection (5 %) of the survey. All suspected fistulae were followed up to confirm a clinical diagnosis. RESULTS: Mean age was 29.5 [standard deviation (SD) 8.05] years. Only 22 % of women were knowledgeable about the symptoms of fistula. The prevalence of all obstetric fistulae was 6:10,000 reproductive-aged women [95 % confidence interval (CI) 3-8], of untreated fistula 2:10,000 (95 % CI 0-4) and of symptomatic POP 100:10,000 (95 % CI 86-114). CONCLUSION: The prevalence of obstetric fistula in these rural zones of Ethiopia is relatively low and reflects a substantial reduction from previous reports. Significant numbers of women suffer with symptomatic POP, for which surgical and nonsurgical treatments would be beneficial. Obstetric fistula in north and east Ethiopia is relatively low; however, the many women with symptomatic pelvic organ prolapse could benefit from treatment.

Evolution of circular and linear polarization in scattering environments.

This work quantifies the polarization persistence and memory of circularly polarized light in forward-scattering and isotropic (Rayleigh regime) environments; and for the first time, details the evolution of both circularly and linearly polarized states through scattering environments. Circularly polarized light persists through a larger number of scattering events longer than linearly polarized light for all forward-scattering environments; but not for scattering in the Rayleigh regime. Circular polarization's increased persistence occurs for both forward and backscattered light. The simulated environments model polystyrene microspheres in water with particle diameters of 0.1 µm, 2.0 µm, and 3.0 µm. The evolution of the polarization states as they scatter throughout the various environments are illustrated on the Poincaré sphere after one, two, and ten scattering events.

Circumferential urethral fistulae in Sub-Saharan Africa, current outcomes and future prospects.

INTRODUCTION AND HYPOTHESIS: Circumferential urethral fistula is a severe form of obstetric injury that is recognized to carry a poor prognosis for eventual continence but this has not been quantified before. METHODS: An analysis of 106 women who had undergone primary repair of a circumferential fistula was carried out with particular reference to whether there complete continence or at least some improvement in remaining dry was reported. RESULTS: Of the 106 women, only 25% reported themselves continent; 19% said there was an improvement. Prognosis was not altered by the distance of the fistula from the external urethral meatus, with 10/62 (16% reporting continence if the fistula was <1.5 cm and 10/44 (13%) if >1.5 cm. There was a 13% primary dehiscence rate. CONCLUSIONS: Current methods of primary urethral fiistula repair carry a poor prognosis for eventual continence. Techniques to lengthen the urethra and provide greater support need to be developed for this unfortunate group of women.