2,446 research outputs found

    Comparison of morphological and chemical fruit traits from different pitaya genotypes (Hylocereus sp.) grown in Costa Rica

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    Physico-chemical parameters of the fruits of five Hylocereus genotypes grown in their natural habitat in Costa Rica were determined and their morphological traits were assessed. Besides, overall dimensions, shape, weight, flesh fraction, skin thickness, seed content and juice yield were recorded. Chemical analyses comprised pH, total soluble solids, titratable acidity, proline and pectin content, formol number and density of the juices. In addition, the major sugars glucose, fructose and sucrose, as well as organic acids were quantified by HPLC. Moreover, skin and flesh firmness were assessed. Significant differences were observed between genotypes concerning fruit weight and dimensions, skin thickness, proportion of flesh and amount of seeds. Whereas lowest pH values were determined in the juices from ‘San Ignacio’, highest malic acid contents in ‘Rosa’ and maximal total soluble solids were found in juices from ‘Nacional’ fruits. Furthermore, differences between genotypes concerning density, pectin and glucose contents of the juices were noted

    U.S. National Security and Climate Change

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    Preliminary results of spectral reflectance studies of tycho crater

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    The preliminary analysis and interpretation of near infrared spectra obtained for both the interior and exterior deposits associated with the Tycho crater is presented. Specific objectives were: (1) to determine the composition and stratigraphy of the highland crust in the Tycho target site; (2) to determine the likely composition of the primary ejecta which may be present in ray deposits; (3) to investigate the nature of spectral units defined in previous studies; (4) to further investigate the nature and origin of both the bright and dark haloes around the rim crest; and (5) to compare the compositions determined for the Tycho units with those of the Aristarchus crater as well as typical highland deposits. The spectra obtained for the interior areas exhibit similar spectral features. These include relatively strong 1 micron absorption bands whose minima are centered between 0.97 and 0.99 microns and shallow to intermediate continuum slopes. The spectra generally exhibit indications of a 1.3 micron feature consistent with the presence of Fe(2+) bearing plagioclase feldspar. The strong 1 micron absorption features indicate a dominant high Ca clinopyroxene component. Results obtained from the ejecta deposits show that the spectrum of the inner, bright halo is almost identical with those obtained for interior units. The spectrum of the dark halo exhibits a wide, relatively shallow absorption feature centered at 1.01 microns, a 1.3 micron absorption, and a steep continuum slope. This spectrum is interpreted as indicating the presence of pyroxene, Fe-bearing feldspar, and a significant component of Fe-bearing impact melt glass. Finally, the spectra of spots inside Tycho show similarity with certain spectra for Aristarchus. However, the suite of spectra obtained for Tycho exhibits a different trend in terms of band center versus width

    An Experimental Approach to Understanding the Optical Effects of Space Weathering

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    The creation and accumulation of nanophase iron (npFe(sup 0)) is the primary mechanism by which spectra of materials exposed to the space environment incur systematic changes referred to as "space weathering." The optical effects of this npFe(sup 0) on lunar soils are well documented. Space weathering though, should occur on the surface of any planetary body that is not protected by an atmosphere. There is no reason to assume that cumulative space weathering products throughout the solar system will be the same as those found in lunar soils. In fact, these products are likely to be very dependent on the specific environmental conditions under which they were produced. We have prepared a suite of analog soils to explore the optical effects of npFe(sup 0). By varying the size and concentration of npFe(sup 0) in the analogs we found significant systematic changes in the Vis/NIR spectral properties of the materials. Smaller npFe(sup 0) (40 nm in diameter) lowers the albedo across the Vis/NIR range with little change in the overall shape of the continuum. Intermediate npFe(sup 0) sizes impact the spectra in a distinct pattern that changes with concentration. The products of these controlled experiments have implications for space-weathered material throughout the inner solar system. Our results indicate that the lunar soil continuum is best modeled by npFe(sup 0) particles with bulk properties in the approx.15-25 nm size range. Larger npFe0 grains result in spectra that are similar in shape to the Mercury continuum. The continuum of S-type asteroid spectra appear to be best represented by small amounts of npFe(sup 0) that is similar to, but slightly smaller on average, than the npFe(sup 0) in lunar soils (approx.10-15 nm)

    Crustal heterogeneity of the moon viewed from the Galileo SSI camera: Lunar sample calibrations and compositional implications

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    Summaries are given of the spectral calibration, compositional parameters, nearside color, and limb and farside color of the Moon. The farside of the Moon, a large area of lunar crust, is dominated by heavily cratered terrain and basin deposits that represent the products of the first half billion years of crustal evolution. Continuing analysis of the returned lunar samples suggest a magma ocean and/or serial magmatism model for evolution of the primordial lunar crust. However, testing either hypothesis requires compositional information about the crustal stratigraphy and lateral heterogeneity. Resolution of this important planetary science issue is dependent on additional data. New Galileo multispectral images indicate previously unknown local and regional compositional diversity of the farside crust. Future analysis will focus on individual features and a more detailed assessment of crustal stratigraphy and heterogeneity

    Points of Interest Coverage with Connectivity Constraints using Wireless Mobile Sensors

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    Part 7: Network Topology ConfigurationInternational audienceThe coverage of Points of Interest (PoI) is a classical requirement in mobile wireless sensor applications. Optimizing the sensors self-deployment over a PoI while maintaining the connectivity between the sensors and the sink is thus a fundamental issue. This article addresses the problem of autonomous deployment o f mobile sensors that need to cover a predefined PoI with a connectivity constraints and provides the solution to it using Relative Neighborhood Graphs (RNG). Our deployment scheme minimizes the number of sensors used for connectivity thus increasing the number of monitoring sensors. Analytical results, simulation results and real implementation are provided to show the efficiency of our algorithm

    The Fine Structure and Outskirts of DDO 154

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    Mapping of the HI disk of the isolated irregular galaxy DDO 154 with the C array of the Very Large Array and with the 3.2' upgraded Arecibo beam is presented. Our results show a truncation (or temporary drop) of the HI disk at a column density around 10^19 atoms cm^-2, consistent with theoretical expectations for the truncation produced by the extragalactic UV field. We also detect a marginally significant levelling off of the HI distribution along the continuation of the major axis at a column density near 2X10^18 atoms cm^-2. The VLA results show that the gas beyond ~6' in radius must be relatively smooth, with no structure larger in size than ~300 pc exhibiting a density contrast of a factor of 10 or more. However, there is considerable few-hundred-parsec scale structure in the gas disk at smaller radii, even well outside the regions where there are visible stars. Two prominent cavities well removed from any significant stellar populations are studied. While the energies required for evacuation are consistent with those produced by multiple supernovae, there is no visible trace of stars within a kpc of the center of the larger cavity, and the smaller of the two cavities is centered just outside the 26.5 mag arcsec^-2 B isophote. The velocity dispersion of the gas, measured within our 270 pc beam, is 7 to 8 km s^-1 throughout the disk (to 6' radius). This translates to a scaleheight of ~700 pc at the point where the rotation curve flattens, at a radius of ~4.5 kpc. Velocity profiles are well fit by single gaussians at all points.Comment: 14 pages, 2 tables, 13 figures, accepted for AJ Nov. 200

    The Mental and Physical Health of Mothers of Children with Special Health Care Needs in the United States

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    OBJECTIVE: To determine the prevalence of poor mental and physical health among mothers of children with special health care needs (CSHCN) and to determine the association between maternal health and the child\u27s number of special health care needs (SHCN) and severity of ability limitation. METHODS: We used the combined 2016-2018 National Survey of Children\u27s Health Dataset of 102,341 children ages 0-17 including 23,280 CSHCN. We used regression models to examine the associations of a child\u27s number of SHCN and ability limitations with maternal health. RESULTS: Twice as many mothers of CSHCN had poor mental and physical health compared to non-CSHCN (mental 10.3% vs. 4.0%, p \u3c .001; physical 11.9% vs 5.0%, p \u3c .001). In regression models, increased number of SHCN and severity of activity limitations were associated with significantly increased odds of poor maternal health. CONCLUSIONS FOR PRACTICE: Mothers of CSHCN have worse health compared to mothers of non-CSHCN, especially those who experience social disadvantage and those with children with complex SHCN or severe ability limitations. Interventions to improve the health of these particularly vulnerable caregivers of CSHCN are warranted

    Discriminating early-stage diabetic retinopathy with subjective and objective perimetry

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    Introduction: To prevent progression of early-stage diabetic retinopathy, we need functional tests that can distinguish multiple levels of neural damage before classical vasculopathy. To that end, we compared multifocal pupillographic objective perimetry (mfPOP), and two types of subjective automated perimetry (SAP), in persons with type 2 diabetes (PwT2D) with either no retinopathy (noDR) or mild to-moderate non-proliferative retinopathy (mmDR). Methods: Both eyes were assessed by two mfPOP test methods that present stimuli within either the central ±15° (OFA15) or ±30° (OFA30), each producing per-region sensitivities and response delays. The SAP tests were 24-2 Short Wavelength Automated Perimetry and 24-2 Matrix perimetry. Results: Five of eight mfPOP global indices were significantly different between noDR and mmDR eyes, but none of the equivalent measures differed for SAP. Per-region mfPOP identified significant hypersensitivity and longer delays in the peripheral visual field, verifying earlier findings. Diagnostic power for discrimination of noDR vs. mmDR, and normal controls vs. PwT2D, was much higher for mfPOP than SAP. The mfPOP per-region delays provided the best discrimination. The presence of localized rather than global changes in delay ruled out iris neuropathy as a major factor. Discussion: mfPOP response delays may provide new surrogate endpoints for studies of interventions for early-stage diabetic eye damage.</p
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