Wavefront Analysis of Adaptive Telescope

The motivation for this work came from a NASA Headquarters interest in investigating design concepts for a large space telescope employing active optics technology. Current and foreseeable launch vehicles will be limited to carrying around 4-5 meter diameter objects. Thus, if a large, filled-aperture telescope (6-20 meters in diameter) is to be placed in space, it will be required to have a deployable primary mirror. Such a mirror may be an inflatable membrane or a segmented mirror consisting of many smaller pieces. In any case, it is expected that the deployed primary will not be of sufficient quality to achieve diffraction-limited performance for its aperture size. Thus, an active optics system will be needed to correct for initial as well as environmentally-produced primary figure errors. Marshall Space Flight Center has developed considerable expertise in the area of active optics with the PAMELA test-bed. The combination of this experience along with the Marshall optical shop's work in mirror fabrication made MSFC the logical choice to lead NASA's effort to develop active optics technology for large, space-based, astronomical telescopes. Furthermore, UAH's support of MSFC in the areas of optical design, fabrication, and testing of space-based optical systems placed us in a key position to play a major role in the development of this future-generation telescope. A careful study of the active optics components had to be carried out in order to determine control segment size, segment quality, and segment controllability required to achieve diffraction-limited resolution with a given primary mirror. With this in mind, UAH undertook the following effort to provide NASA/MSFC with optical design and analysis support for the large telescope study. All of the work performed under this contract has already been reported, as a team member with MSFC, to NASA Headquarters in a series of presentations given between May and December of 1995. As specified on the delivery order, this report simply summarizes the material with the various UAH-written presentation packages attached as appendices

Wavefront Analysis of Adaptive Telescope

The motivation for this work came from a NASA Headquarters interest in investigating design concepts for a large space telescope employing active optics technology. The development of telescope optical requirements and potential optical design configurations is reported

The wider value of rural rail provision

In the context of recent plans for public sector expenditure, the value for money provided by rural public transport is an important issue in Britain and elsewhere, and one aspect of this is the option and non-use value placed on public transport by residents. Whilst there are a small number of studies which have estimated option and non-use values, they rest largely on contingent valuation methods which are subject to dangers of bias, and concentrate on commuter services into cities rather than truly rural services. This paper seeks to overcome these problems by conducting a Stated Preference (SP) experiment in rural communities, which values the provision of rail services and compares this against Post Office provision. We believe that using this approach, and allowing respondents to compare willingness to pay for rail services with that for another important rural service subject to threatened cuts, should produce more reliable results; moreover we achieve this using self completion questionnaires rather than much more expensive interviews. Our results show much lower values for rail than previous studies, though this is to be expected in truly rural areas where the likelihood of commuting by rail is much lower. Other non-use values are greater than option values in this context

Correlation of ISO 16840-2:2007 impact damping and hysteresis measures for a sample of wheelchair seating cushions

Hysteresis and impact damping measures were made on 37 wheelchair seating cushions according to ISO 16840-2:2007 Wheelchair seating—Part 2: Determination of physical and mechanical characteristics of devices intended to manage tissue integrity—seat cushions. These measures were then correlated using Spearman and Pearson correlations to investigate the relationship between them. Correlations were also conducted on the subset of cushions comprising only those with planar foam construction. Correlation between the hysteresis measures (h250 and h500) and the mean number of rebounds greater in amplitude than 10% of the peak acceleration amplitude (R10%) were weak, as were the correlations between the hysteresis measures and the mean peak first rebound acceleration (aa). Correlations between hysteresis and the mean peak second rebound acceleration (a2), and also hysteresis and the ratio of first and second peak (a2:aa) however were moderate. Results demonstrate that the relationship between these two measures is complex. The assertion implicit in ISO 16840-2:2007 is that the two measures are related, but this study shows that these should not be assumed to be equivalent or used interchangeably

The roles of intolerance of uncertainty, anxiety sensitivity and distress tolerance in hoarding disorder compared with OCD and healthy controls

Background: It is suggested that the different psychological vulnerability factors of intolerance of uncertainty (IU), anxiety sensitivity (AS) and distress tolerance (DT) may be in important in hoarding disorder (HD). However, the extent to which these factors are specific to HD compared with other disorders remains unclear. Aims: The current study aimed to investigate differences in IU, AS and DT in three groups: HD (n=66), obsessive compulsive disorder (OCD; n=59) and healthy controls (HCs; n=63). Method: Participants completed an online battery of standardised self-report measures to establish the independent variable of group membership (HD, OCD and HC) and the dependent variables (IU, AS and DT). Results: A MANOVA analysis indicated statistically significant differences in IU, AS and DT between the clinical groups and HCs. Follow-up analyses showed no statistically significant differences between the HD and OCD group for any of the three constructs. The results remained the same when examining the effects of co-morbid HD and OCD. An unexpected finding was the trend for IU, AS and DT to be more severe when HD and OCD were co-morbid. Conclusions: The evidence suggests the absence of a specific relationship between IU, AS or DT in HD and instead is consistent with existing research which suggests that these psychological vulnerability factors are transdiagnostic constructs across anxiety disorders. The implications of the findings are discussed

Measuring Energetics of Biological Processes

Measurement of the energetics of biological processes is the key component in understanding the thermodynamic responses of homoeothermic animals to their environments. For these animals to achieve body temperature control, they must adapt to thermal-environmental conditions and variations caused by weather (the meteorological condition of a region), climate, vegetation, topography, and shelters (see Figures 2 and 3 of Chapter 1). Adaptation can take different forms as defined by Hafez (1968). Physiological adaptation is the capacity and process of adjustment of the animal to itself, to other living material, and to its external physical environment. Genetic adaptation refers to the selection and heritability of characteristics for a particular environment or climatic region. A long-term adaptive physiological adjustment is referred to as acclimatization. We know this occurs through observations of animal conformation, animal types, respiratory rate, color, behavior, food selection, etc. Since adaptation of the animal to its thermal environment requires regulation of body temperature, measurement of that adaptation through animal energetics provides an indicator of the extent and energetic cost of adaptation

Rational Design of Carbon Nitride Photoelectrodes with High Activity Toward Organic Oxidations

Carbon nitride (CNx) is a light-absorber with excellent performance in photocatalytic suspension systems, but the activity of CNx photoelectrodes has remained low. Here, cyanamide-functionalized CNx (NCNCNx) was co-deposited with ITO nanoparticles on a 1.8 Å thick alumina-coated FTO electrode. Transient absorption spectroscopy and impedance measurements support that ITO acts as a conductive binder and improves electron extraction from the NCNCNx, whilst the alumina underlayer reduces recombination losses between the ITO and the FTO glass. The Al2O3|ITO : NCNCNx film displays a benchmark performance for CNx-based photoanodes with an onset of −0.4 V vs a reversible hydrogen electrode (RHE), and 1.4±0.2 mA cm−2 at 1.23 V vs RHE during AM1.5G irradiation for the selective oxidation of 4-methylbenzyl alcohol. This assembly strategy will improve the exploration of CNx in fundamental and applied photoelectrochemical (PEC) studies.The authors thank Dr. Carla Casadevall, Dr. Motiar Rahaman, and Dr. Mark Bajada (University of Cambridge) for helpful discussions. This work was funded by the European Union's Horizon 2020 project SOLAR2CHEM (Marie Skłodowska-Curie Actions with Grant Agreement No. 861151, C.P., E.R.) and Methasol (Grant Agreement No. 101022649, S.A.J.H., J.D.), the EPSRC (NanoDTC, EP/L015978/1, and EP/S022953, T.U., E.R.), Generalitat Valenciana (APOSTD/2021/251 fellowship, C.A.M.), and the project PID2020-116093RB-C41 by MCIN/AEI/10.13039/501100011033/ (S.G.). The authors acknowledge the use of the Cambridge XPS System, which is part of Sir Henry Royce Institute - Cambridge Equipment, EPSRC grant EP/P024947/1, and the EPSRC Underpinning Multi-User Equipment Call (EP/P030467/1) for the Talos F200X G2 TEM

Analyzing the effects of lactose on calcium absorption in premature infants using HR-ICP-Mass Spectrometry

Abstract only availableWith advances in neonatal care, premature infants are surviving at increasing rates. During the third trimester of pregnancy, the bone mineral content of infants rapidly increases. It is therefore becoming essential to accurately mimic the womb environment to maintain growth and sustain the health of premature infants as if they were in utero. Regulating calcium absorption in premature infants is crucial primarily for bone formation, as 99% of the calcium in the human body is found in the bones and the teeth. The effect of lactose containing formulas on calcium absorption in premature infants has not been well established. Concerns have been noted in the scientific community regarding lactose intolerance especially in premature infants, as lactase, the enzyme responsible for lactose digestion, is most readily detectible during the third trimester of pregnancy. In this study, in conjunction with Dr. Laura Hillman of the University of Missouri Hospital, each infant was fed lactose and maltose formulas during different weeks using a dual tracer method in which two calcium isotopes were administered, 44Ca orally and 46Ca intravenously. Urine samples were collected after 24 hours. Analysis related natural abundances of calcium isotopes to the measured values in the urine. Polyatomic ion interferences were differentiated from the calcium peaks by analyzing the samples at a resolution of 4000. Mathematical corrections for interferences caused by titanium and doubly charged strontium were determined by measuring the specific isotopes 47Ti and 87Sr++ and using known natural abundances of the interfering isotopes to correct each calcium count rate. Mathematical calculations relate the enriched isotope ratio measurements of 44Ca and 46Ca to calcium absorption. Analysis regarding the effect of lactose on calcium absorption is ongoing. Our data precision on the ICP-MS was acceptable with percent relative standard deviations (%RSD) for external precision over the course of a week at 1.4, 2.2, 0.71, and 1.4 for isotope ratios 42Ca: 43Ca, 42Ca: 44Ca, 42Ca: 46Ca, and 42Ca: 48Ca respectively. Daily internal precision (%RSD) values were .37, 1.3, .69, and 1.5. The precision shows the viability of utilizing HR-ICP-MS analysis for calcium isotope ratios.NSF-REU/NIH Program in Radiochemistr

Electron Accumulation Induces Efficiency Bottleneck for Hydrogen Production in Carbon Nitride Photocatalysts.

This study addresses the light intensity dependence of charge accumulation in a photocatalyst suspension, and its impact on both charge recombination kinetics and steady-state H2 evolution efficiency. Cyanamide surface functionalized melon-type carbon nitride (NCNCNx) has been selected as an example of emerging carbon nitrides photocatalysts because of its excellent charge storage ability. Transient spectroscopic studies (from ps to s) show that the bimolecular recombination of photogenerated electrons and holes in NCNCNx can be well described by a random walk model. Remarkably, the addition of hole scavengers such as 4-methylbenzyl alcohol can lead to ∼400-fold faster recombination kinetics (lifetime shortening to ∼10 ps). We show that this acceleration is not the direct result of ultrafast hole extraction by the scavenger, but is rather caused by long-lived electron accumulation in NCNCNx after hole extraction. The dispersive pseudo-first order recombination kinetics become controlled by the density of accumulated electrons. H2 production and steady-state spectroscopic measurements indicate that the accelerated recombination caused by electron accumulation limits the H2 generation efficiency. The addition of a reversible electron acceptor and mediator, methyl viologen (MV2+), accelerates the extraction of electrons from the NCNCNx and increases the H2 production efficiency under one sun irradiation by more than 30%. These results demonstrate quantitatively that while long-lived electrons are essential to drive photoinduced H2 generation in many photocatalysts, excessive electron accumulation may result in accelerated recombination losses and lower performance, and thus highlight the importance of efficient electron and hole extraction in enabling efficient water splitting photocatalysts.ERC AdG Intersolar grant (Grant No. 291482), The Christian Doppler Research Association The OMV Grou