Search

Ocular injuries are the most common cause of preventable blindness in children. A detailed and systematic evaluation of patients with ocular trauma will reduce morbidity and improve long-term vision outcomes. This issue reviews the critical aspects of the pediatric ocular examination for accurate diagnosis of vision-threatening injuries. It also provides recommendations for immediate emergency department treatment, and indications for urgent versus emergent ophthalmology referral.

Perovskite photovoltaics (PVs) are under intensive development for promise in terrestrial energy production. Soon, the community will find out how much of that promise may become reality. Perovskites also open new opportunities for lower cost space power. However, radiation tolerance of space environments requires appropriate analysis of relevant devices irradiated under representative radiation conditions. We present guidelines designed to rigorously test the radiation tolerance of perovskite PVs. We review radiation conditions in common orbits, calculate nonionizing and ionizing energy losses (NIEL and IEL) for perovskites, and prioritize proton radiation for effective nuclear interactions. Low-energy protons (0.05–0.15 MeV) create a representative uniform damage profile, whereas higher energy protons (commonly used in ground-based evaluation) require significantly higher fluence to accumulate the equivalent displacement damage dose due to lower scattering probability. Furthermore, high-energy protons may “heal” devices through increased electronic ionization. These procedural guidelines differ from those used to test conventional semiconductors.

Radiation hard thin-film solar cell technologies are necessary in order to achieve a step forward in the specific power of solar arrays for space applications. In this article, we analyze the degradation of nanowire (NW) solar cells under high energy particles. GaAs NW solar cells have been irradiated with protons of 100 and 350 keV at different fluences. The radiation hardness of the NW solar cells in all the cases is remarkable in comparison with GaAs planar solar cells and prior literature. Design guidelines to optimize the specific power of NW solar cells for space applications by jointly increasing their efficiency and radiation hardness are presented.

We develop lattice-mismatched GaInAsP as an alternative alloy to pure As-based alloys currently used in III–V multijunction solar cells. Increasing the alloy phosphorous and indium content while maintaining an optimal bandgap may allow high efficiency multijunction devices with increased radiation hardness. Here, 1.0-eV GaInAsP is developed and implemented into single and multijunction solar cell devices. The lattice-mismatched GaInAsP must be grown strain free, and the subcell thickness must be maintained below the thickness where surface-driven phase separation occurs. As observed in transmission electron microscopy and cathodoluminescence imaging, phase separation strengthens in the GaInAsP layer and leads to interfacial defect formation when the cell thickness is too great. We show single junction 1.0-eV Ga0.5In0.5As0.7P0.3 with excellent carrier collection and a bandgap-voltage offset of 0.40 V. This material quality approaches that of 1.0-eV Ga0.7In0.3As used in inverted metamorphic multijunction devices, but has increased phosphorus content and consequently is expected to have a higher radiation resistance. We incorporate the 1.0-eV GaInAsP subcell into a 3-junction inverted metamorphic solar cell to test the performance of the subcell in a multijunction. No additional loss is observed upon integration into a multijunction cell: both the carrier collection and voltage of the GaInAsP subcell are unchanged from single junction devices. While further materials development and radiation testing is still required, these preliminary results indicate that lattice-mismatched GaInAsP can be effectively used in multijunction solar cells to replace radiation-soft materials.

Objective This project sought to investigate whether an association may be observed between isotopic stress indicators and skeletal evidence of pathological conditions. Materials Deciduous and permanent teeth of 15 non-adults from two contemporaneous mid-19th century London burial grounds (City Bunhill, Lukin Street). Methods δ13C and δ15N was measured in the incrementally sectioned dentine collagen. Isotopic profiles for each individual included death during tooth development. Results Individuals with skeletal evidence of chronic pathological conditions (e.g., rickets, tuberculosis) exhibited raised δ15N values of 0.5–1.7‰ in the months prior to death. Isotopic change consistent with chronic physiological stress prior to death was also recorded in two individuals with no skeletal evidence of disease. An offset was observed between co-forming bone and dentine δ15N values in both populations, indicating that bone and dentine are not recording the same isotopic changes. Conclusions Isotopic change consistent with chronic physiological stress was observed in both those with and without skeletal evidence of disease, suggesting that adaptation to chronic stress in childhood was not uncommon within these 19th century London populations. Significance Chronic physiological stress prior to death may be seen in the incrementally sampled dentine of non-adults who die during tooth formation. Limitations The temporal resolution of current dentine micro-sampling methods may mask or minimise visibility of shorter-term periods of stress or dietary change. Suggestions for further research Future research should further explore the relationship between specific skeletal pathologies and isotopic evidence for stress.

AeroCube-10 is a two-CubeSat mission built and operated by The Aerospace Corporation. Among several payloads is a space solar cell experiment designed to measure solar cell radiation damage as well as the space radiation environment believed to cause it. This paper describes first on-orbit results of the space solar cell experiment on AeroCube-10.

In outer space down to the altitudes routinely flown by larger aircrafts, radiation can pose serious issues for microelectronics circuits. The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron and home of the Berkeley Accelerator Space Effects Facility, where the effects of energetic particles on sensitive microelectronics are studied with the goal of designing electronic systems for the space community. This paper describes the flexibility of the facility and its capabilities for testing the bombardment of electronics by heavy ions, light ions, and neutrons. Experimental capabilities for the generation of neutron beams from deuteron breakups and radiation testing of carbon nanotube field effect transistor will be discussed.

The second plague pandemic, caused by Yersinia pestis, devastated Europe and the nearby regions between the 14th and 18th centuries AD. Here we analyse human remains from ten European archaeological sites spanning this period and reconstruct 34 ancient Y. pestis genomes. Our data support an initial entry of the bacterium through eastern Europe, the absence of genetic diversity during the Black Death, and low within-outbreak diversity thereafter. Analysis of post-Black Death genomes shows the diversification of a Y. pestis lineage into multiple genetically distinct clades that may have given rise to more than one disease reservoir in, or close to, Europe. In addition, we show the loss of a genomic region that includes virulence-related genes in strains associated with late stages of the pandemic. The deletion was also identified in genomes connected with the first plague pandemic (541–750 AD), suggesting a comparable evolutionary trajectory of Y. pestis during both events., The second plague pandemic, caused by Yersinia pestis, started in the 14th century and recurred in Europe until the 18th century. Here, the authors reconstruct ancient Y. pestis genomes from human remains spanning this period, shedding light into the phylogeography and population structure of the European strains.

Space power systems require photovoltaics that are lightweight, efficient, reliable, and capable of operating for years or decades in space environment. Current solar panels use planar multijunction, III-V based solar cells with very high efficiency, but their specific power (power to weight ratio) is limited by the added mass of radiation shielding (e.g., coverglass) required to protect the cells from the high-energy particle radiation that occurs in space. Here, we demonstrate that III-V nanowire-array solar cells have dramatically superior radiation performance relative to planar solar cell designs and show this for multiple cell geometries and materials, including GaAs and InP. Nanowire cells exhibit damage thresholds ranging from ∼10-40 times higher than planar control solar cells when subjected to irradiation by 100-350 keV protons and 1 MeV electrons. Using Monte Carlo simulations, we show that this improvement is due in part to a reduction in the displacement density within the wires arising from their nanoscale dimensions. Radiation tolerance, combined with the efficient optical absorption and the improving performance of nanowire photovoltaics, indicates that nanowire arrays could provide a pathway to realize high-specific-power, substrate-free, III-V space solar cells with substantially reduced shielding requirements. More broadly, the exceptional reduction in radiation damage suggests that nanowire architectures may be useful in improving the radiation tolerance of other electronic and optoelectronic devices.

A commercially available extended UV supercontinuum laser was tuned with a 128-pixel transmissive spatial light modulator to give a close match with the ASTM E490 AM0 solar spectrum. Another 1088-pixel reflective spatial light modulator was added to increase tunability. Because of the small spot size of the laser beam, the effect of size on light current-voltage (IV) measurement was investigated. We propose using an I SC - V OC curve to reconstruct a series resistant free full cell light IV curve.

AM0 solar cell measurements currently require calibrated balloon standards for tuning solar simulators. The uncertainty in the solar cell measurement is largely dependent on the quality of the calibrated balloon standard used to tune the simulator. Current practices reduce this uncertainty to ∼1% while requiring expensive and infrequent methods for obtaining new calibration standards. This paper outlines an effort to reduce the uncertainty of the calibration standard, while providing a solution for low cost and frequent standard creation.

The Aerospace Corporation’s AeroCube-6 nanosatellites collected simultaneous on-orbit micro-dosimeter and experimental solar cell data. Building on the results of this previous mission, we have developed new instrumentation and a new experiment to better characterize on-orbit degradation of space solar cells while measuring the charged particle radiation causing it. This paper discusses initial ground test results and instrument development efforts for a payload to be flown on a new mission, called AeroCube-10.

We combined light current-voltage, dark currentvoltage, quantum efficiency, and electroluminescence at varying low temperatures to identify and quantify defects, current mismatch effects, saturation currents, and diode quality of each subcell. We attempt to provide a method for spectral mismatch correction for fill factor for each subcell as well as identify how defects, current mismatch, and radiation will affect performance of multijunction solar cells at LILT, AM 0, and AM 1.5.

Transient absorption decay rate constants (k_(obs)) for reactions of electronically excited zinc tetraphenylporphyrin (^3ZnTPP*) with triruthenium oxo-centered acetate-bridged clusters [Ru_3(μ_3-O)(μ-CH_3CO_2)_6(CO)(L)]_2(μ-pz), where pz = pyrazine and L = 4-cyanopyridine (cpy) (1), pyridine (py) (2), or 4-dimethylaminopyridine (dmap) (3), were obtained from nanosecond flash-quench spectroscopic data (quenching constants, k_q, for ^3ZnTPP*/1–3 are 3.0 × 10^9, 1.5 × 10^9, and 1.1 × 10^9 M^(–1) s^(–1), respectively). Values of k_q for reactions of ^3ZnTPP* with 1–3 and Ru_3(μ_3-O)(μ-CH_3CO_2)_6(CO)(L)_2 [L = cpy (4), py (5), dmap (6)] monomeric analogues suggest that photoinduced electron transfer is the main pathway of excited-state decay; this mechanistic proposal is consistent with results from a photolysis control experiment, where growth of characteristic near-IR absorption bands attributable to reduced (mixed-valence) Ru_3O-cluster products were observed.

We present results from proton radiation experiments with carbon nanotube field effect transistors. Single event effects were observed consisting of drops in current, with very long durations (100 s of ms), and sudden, discrete switching events between quantized current levels. These studies are important for the development and understanding of advanced nano-electronic devices operating in the space radiation environment.

Concentrator photovoltaic systems can provide supplementary shielding against high energy particles. In this paper we compare the radiation environment that the same solar cell would experience in a flat-plate module versus in a parabolic mirror concentrator system. We have observed that the shielding provided by the concentrator system is remarkable. In order to obtain an accurate prediction of the overall shield needed in our concentrator system triple-junction space solar cells have been irradiated on the edge with 350-keV protons at a fluence of 1012P + cm−2. A mild degradation of the open circuit voltage was measured (~70 mV).

The degradation of individual subcell J - V parameters, such as short circuit current, open circuit voltage, fill factor, and power of a GaInP/GaInAs/Ge triple junction solar cell by 1 MeV electrons were derived utilizing the spectral reciprocity relation between electroluminescence and external quantum efficiency. After exposure to a fluence of 1 × 1015 1 MeV electrons, it was observed that up to 67 % of the voltage loss is from the middle, GaInAs sub cell. Also, the dark saturation current of the Ge and GaInAs subcells increased but a simultaneous decrease in ideality factor caused a reduction of the open circuit voltage. The reduced ideality factor further indicates a change in the primary recombination mechanism.

We report the effects of high energy electron and proton radiation on perovskite solar cells. For irradiation with 1 MeV electrons, at fluence from 1012 to 1016 cm−2, there are no significant changes in the morphology and the crystal phase in the perovskites, and the perovskite solar cells show only slight degradation in photovoltaic performance and spectral response. The results from Monte Carlo simulations show most of the electrons completely penetrate through all of the layers of solar cells with little scattering. In addition, 50 ke V proton radiation with fluence of 1012−2 has no significant impact on the open-circuit voltage or short-circuit current, and degrades only the fill factor. We have further found that the fill factor can be restored with a vacuum annealing process. The results suggest that perovskites have superior electron and proton radiation tolerance, and thus hold particular promise for space applications.

The London Hospital, located in the heart of the East End, grew in tandem with the industrialization and increasing population of an impoverished area of the capital. It provided care and emergency facilities to employees of local industries amongst others. Archaeological excavations uncovered a forgotten burial ground for poor patients. Osteological and documentary evidence combined to reveal that many of the dead were first given to the hospital medical school for anatomical study. Human dissection no doubt contributed to scientific development within the medical profession, but the practice came with consequences that many at the time found unpalatable.

Treponematosis is a syndrome of chronic infectious diseases. There has been much debate on its origins and spread, particularly with regard to venereal syphilis, an unsightly and debilitating disease in preantibiotic populations. The osteological analysis of 5,387 individuals excavated by Museum of London Archaeology from the medieval burial ground of St. Mary Spital in London (dated c 1120-1539) provided an unprecedented opportunity to investigate the nature and prevalence of disease over a period of time. Twenty-five individuals were found with suspected treponematosis, originating from all but the earliest period of the burial ground. Descriptions of affected individuals from each period, together with supporting images, are provided. In this work, particular emphasis was given to the distribution of lesions on the skeleton and the variation in patterns by sex and over time. Little change was observed in the distribution of bony change between individuals dated to pre- and post-Columbian periods. However, a dramatic rise in the prevalence of the disease in the final period (c 1400-1539) may reflect documentary reports of a European epidemic from the late 15th century.

The Aerospace Corporation has been building, testing, and flying miniature satellites in the pico-and nano-satellite class for over a decade. Significant advances have been made to the bus avionics unit and other satellite subsystems during this time. The advances have enabled various on-orbit tests and experiments, one of which has been to host space solar cell experiment payloads. Recent solar cell flight experiments on Aerospace's CubeSats (AeroCubes) demonstrated several subsystems can simultaneously operate to obtain precise measurements of space solar cell performance. Low cost, rapid return CubeSat missions can be valuable development tools for advancing the readiness level of space technologies.

This paper will present some of the challenges in testing and certifying Interval Management (IM) avionics. Historically, standards for avionics running airborne applications have defined test procedures that allow the system performance to be tested using open-loop methods. In these cases the system performance is primarily a function of the avionics. For Interval Management, the system performance is based on the IM avionics, as well as the aircraft performance and environmental disturbances. Due to the interactions between the IM Avionics and the aircraft, Interval Management performance must be tested in a closed-loop environment. The closed-loop test architecture involves evaluating the IM spacing algorithm with a standardized aircraft and control model such that speed commands issued by the IM avionics are implemented by the aircraft, and the aircraft states are updated per the model and fed back to the IM avionics.

Titanium (IV) dioxide (TiO_2) nanoparticles (NPs) with a 1–5 nm diameter were synthesized by a sol–gel method, functionalized with carboxylate ligands, and combined with carbon black (CB) to produce chemiresistive chemical vapor sensor films. The TiO_2 acted as an inorganic support phase for the swellable, organic capping groups of the NPs, and the CB imparted electrical conductivity to the film. Such sensor composite films exhibited a reproducible, reversible change in relative differential resistance upon exposure to a series of organic test vapors. The response of such chemiresistive composites was comparable to, but generally somewhat smaller than, that of thiol-capped Au NPs. For a given analyte, the resistance response and signal-to-noise ratio of the capped TiO_2-NP/CB composites varied with the identity of the capping ligand. Hence, an array of TiO_2-NP/CB composites, with each film having a compositionally different carboxylate capping ligand, provided good vapor discrimination and quantification when exposed to a series of organic vapors. Principal components analysis of the relative differential resistance response of the sensor array revealed a clear clustering of the response for each analyte tested. This approach expands the options for composite-based chemiresistive vapor sensing, from use of organic monomeric or polymeric sorbent phases, to use of electrically insulating capped inorganic NPs as the nonconductive phase of chemiresistive composite vapor sensors.

Background— Lung hypoplasia and persistent pulmonary hypertension of the newborn limit survival in congenital diaphragmatic hernia (CDH). Unlike other diseases resulting in persistent pulmonary hypertension of the newborn, infants with CDH are refractory to inhaled nitric oxide (NO). Nitric oxide mediates pulmonary vasodilatation at birth in part via cyclic GMP production. Phosphodiesterase type 5 (PDE5) limits the effects of NO by inactivation of cyclic GMP. Because of the limited success in postnatal management of CDH, we hypothesized that antenatal PDE5 inhibition would attenuate pulmonary artery remodeling in experimental nitrofen-induced CDH. Methods and Results— Nitrofen administered at embryonic day 9.5 to pregnant rats resulted in a 60% incidence of CDH in the offspring and recapitulated features seen in human CDH, including structural abnormalities (lung hypoplasia, decreased pulmonary vascular density, pulmonary artery remodeling, right ventricular hypertrophy), and functional abnormalities (decreased pulmonary artery relaxation in response to the NO donor 2-( N , N -diethylamino)-diazenolate-2-oxide). Antenatal sildenafil administered to the pregnant rat from embryonic day 11.5 to embryonic day 20.5 crossed the placenta, increased fetal lung cyclic GMP and decreased active PDE5 expression. Antenatal sildenafil improved lung structure, increased pulmonary vessel density, reduced right ventricular hypertrophy, and improved postnatal NO donor 2-( N , N -diethylamino)-diazenolate-2-oxide–induced pulmonary artery relaxation. This was associated with increased lung endothelial NO synthase and vascular endothelial growth factor protein expression. Antenatal sildenafil had no adverse effect on retinal structure/function and brain development. Conclusions— Antenatal sildenafil improves pathological features of persistent pulmonary hypertension of the newborn in experimental CDH and does not alter the development of other PDE5-expressing organs. Given the high mortality/morbidity of CDH, the potential benefit of prenatal PDE5 inhibition in improving the outcome for infants with CDH warrants further studies.

The study of anatomy in England during the 18th and 19th century has become infamous for bodysnatching from graveyards to provide a sufficient supply of cadavers. However, recent discoveries have improved our understanding of how and why anatomy was studied during the enlightenment, and allow us to see the context in which dissection of the human body took place. Excavations of infirmary burial grounds and medical school cemeteries, study of hospital archives, and analysis of the content of surviving anatomical collections in medical museums enables us to re-evaluate the field from a fresh perspective. The pathway from a death in poverty, sale of the corpse to body dealer, dissection by anatomist or medical student, and either the disposal and burial of the remains or preservation of teaching specimens that survive today in medical museums is a complex and fascinating one.

The harmful effects of smoking are now proven, but to what extent can tobacco use be identified in 19th-century skeletal remains? The full osteological analysis of 705 individuals from the cemetery of St Mary and St Michael (open 1843–54) in Whitechapel, London, revealed a high prevalence of pipe smoking amongst the male population. In addition to a lower life expectancy, the smokers were found to have increased levels of skeletal evidence for lung disease when compared to the remainder of the sample. This has implications for the health, social structure and cohesion of this Irish migrant population.

Calibration of individual zones in a multi-source solar simulator using isotype reference cells presents unique challenges. Higher bandgap materials are used as filter layers to match the spectral response of an active isotype cell to its corresponding response in a full multijunction cell. Experimental results suggest that luminescence from these filter layers could occur during calibration of isotype references, thereby artificially increasing the current output. We show that proton irradiation of the filter layers can quench radiative recombination within these layers thereby reducing the luminescent coupling. We also take a look at transient responses from some isotype cells.

A decrease in ideality factor of GaAs solar cells due to irradiation with 1MeV electron radiation resulted in decreased open circuit voltage and maximum power. Dark current-voltage measurements suggest that 1 MeV electron radiation primarily affects dark current produced at voltages greater than 0.5 V. The dark saturation current of irradiated solar cells increased but a simultaneous decrease in ideality factor caused a reduction of the open circuit voltage. The reduced ideality factor further indicates a change in the primary recombination mechanism.

We are investigating the properties of corrole-sensitized TiO 2 solar cells. The TiO 2-adsorbed free base and Ga III corroles display cell efficiencies under AM 1.5 illumination that are about half that of a standard N 3-sensitized cell ( N 3 = cis-bis(4,4'-dicarboxy-2,2'-bipyridine)dithiocyanato ruthenium(II)), while that of the Sn IV-based cell is much lower. The properties of the corrole- TiO 2 solar cells, along with results obtained with electrodes of lower conduction band energies clearly reveal that the reducing power of the singlet excited states of the free base and Ga III corrole, but not of the Sn IV derivative, is sufficiently high for efficient injection into the TiO 2 conduction band.

Recently discovered snake fossils from the Pliocene (Blancan, approximately 2.85–2.95 MYBP) Taunton local fauna, Adams County, Washington, consist of eight genera and at least nine species representing one boid, seven colubrids, and one viperid. Two of the colubrids are extinct (Elaphe pliocenica and a new genus and species). Tauntonophis morganorum is described as a new genus and species. Biogeographically the Taunton snake assemblage is most similar taxonomically to the Recent snake fauna from the Klamath Mountains Province of southwestern Oregon. From a paleoclimatic stand point, the Taunton snakes suggest that this area of the Columbia Basin had a milder, moister climate approximately 2.85–2.95 MYBP.

Nanocrystalline MgA12O4 was synthesized by pyrolysis of the homogeneous spinel precursor, Mg(C4H5O2)2·(H2O):Al2(OH)3(C3H3O2)3·(H2O)2:NH4(C3H3O2)·(H2O). The spinel precursor gel is composed of a mixture of magnesium and aluminum acrylate salts dissolved in an ammonium acrylate gel. The reaction of acrylic acid with magnesium hydroxide in water produced magnesium methacrylate, and a similar reaction of basic aluminum acetate produced the aluminum salt of acrylic acid. The reaction of acrylic acid with ammonium hydroxide produced the ammonium acrylate gel. Ammonium acrylate gel was found to absorb many times its own weight of water. Although similar properties have been identified in PMMA and in the polymer of sodium acrylate, only the ammonium acrylate gel exists as an unpolymerized monomer. The spinel precursor gel is a pre-ceramic material that yields an amorphous oxide phase at 425°C that begins to crystallize to the MgAl2O4 spinel at 600°C and is fully crysta1line at 1030°C with a uniform particle size of 7–100 nm. The spinel precursor gel and the nanocrystalline MgA12O4 spinel were characterized by XRD and TEM.

The degradation of individual subcell J-V parameters, such as short circuit current, open circuit voltage, fill factor, and power of a GaInP/GaInAs/Ge triple junction solar cell by 1 MeV electrons were derived utilizing the spectral reciprocity relation between electroluminescence and external quantum efficiency. After exposure to a fluence of 1 × 1015 1 MeV electrons, it was observed that up to 67% of the voltage loss is from the middle, GaInAs subcell. Also, the dark saturation current of the Ge and GaInAs subcells increased but a simultaneous decrease in ideality factor caused a reduction of the open circuit voltage. The reduced ideality factor further indicates a change in the primary recombination mechanism.

An absolute increase of 3.73% in the end-of-life efficiency of a six junction, series connected, monolithic solar cell can be achieved as determined by detailed balance calculations. Multijunction solar cells were designed and optimized for three solar spectra: AM 0, AM 0 under a MgF2/ITO coated cerium-doped borosilicate glass, and AM0 under MgF2/ITO cerium-doped borosilicate glass that was irradiated with proton energies and fluences equivalent to 15 years in a GEO orbit. Also, the difference between end-of-life and beginning-of-life efficiency decreases for multi-junction solar cells designed for end-of-life versus those designed for beginning-of-life conditions.

Metallic single-walled carbon nanotube (SWNT) films on space qualified solar cell coverglass were irradiated with 100 keV protons at doses of 1 × 1013 and 1 × 1014 protons/cm2. The samples were analyzed using UV-vis-NIR spectroscopy, Raman spectroscopy, and four-point probe measurements. The results indicate that defects are not introduced into the metallic carbon nanotubes after irradiation.

The study of anatomy in England during the 18th and 19th century has become infamous for bodysnatching from graveyards to provide a sufficient supply of cadavers. However, recent discoveries have improved our understanding of how and why anatomy was studied during the enlightenment, and allow us to see the context in which dissection of the human body took place. Excavations of infirmary burial grounds and medical school cemeteries, study of hospital archives, and analysis of the content of surviving anatomical collections in medical museums enables us to re-evaluate the field from a fresh perspective. The pathway from a death in poverty, sale of the corpse to body dealer, dissection by anatomist or medical student, and either the disposal and burial of the remains or preservation of teaching specimens that survive today in medical museums is a complex and fascinating one.