3,022 research outputs found

    Habitability: CAMELOT 4

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    During 1988 to 1989 the NASA/USRA Advanced Design Program sponsored research and design efforts aimed at developing habitability criteria and at defining a habitability concept as a useful tool in understanding and evaluating dwellings for prolonged stays in extraterrestrial space. The Circulating Auto sufficient Mars-Earth Luxurious Orbital Transport (CAMELOT) was studied as a case in which the students would try to enhance the quality of life of the inhabitants by applying architectural design methodology. The study proposed 14 habitability criteria considered necessary to fulfill the defined habitability concept, which is that state of equilibrium that results from the interaction between components of the Individual Architecture Mission Complex, which allows a person to sustain physiological homeostatis, adequate performance, and acceptable social relationships. Architecture, design development, refinements and revisions to improve the quality of life, new insights on artificial gravity, form and constitution problems, and the final design concept are covered

    All-angle negative refraction of highly squeezed plasmon and phonon polaritons in graphene-boron nitride heterostructures

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    A fundamental building block for nanophotonics is the ability to achieve negative refraction of polaritons, because this could enable the demonstration of many unique nanoscale applications such as deep-subwavelength imaging, superlens, and novel guiding. However, to achieve negative refraction of highly squeezed polaritons, such as plasmon polaritons in graphene and phonon polaritons in boron nitride (BN) with their wavelengths squeezed by a factor over 100, requires the ability to flip the sign of their group velocity at will, which is challenging. Here we reveal that the strong coupling between plasmon and phonon polaritons in graphene-BN heterostructures can be used to flip the sign of the group velocity of the resulting hybrid (plasmon-phonon-polariton) modes. We predict all-angle negative refraction between plasmon and phonon polaritons, and even more surprisingly, between hybrid graphene plasmons, and between hybrid phonon polaritons. Graphene-BN heterostructures thus provide a versatile platform for the design of nano-metasurfaces and nano-imaging elements.Comment: 16 pages; 3 figure

    Effects of Environmental Enrichment in Maternally Separated Rats: Age and Sex-Specific Outcomes

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    Maternal separation (MS) early in life is related to an increase in anxiety and depressive-like behaviors and neurobiological alterations mostly related to alterations in hypothalamic pituitary adrenal (HPA) axis reactivity. Environmental enrichment (EE) has been used to ameliorate the effects of MS. However, the outcomes of this intervention at different developmental periods after MS have not been studied. We subjected male and female Sprague-Dawley pups to MS and subsequently compared the effects of EE started either in the pre-pubertal period [postnatal day (PND) 22] or adulthood (PND 78). Anxiety and depressive-like behaviors as well as in hippocampal synaptic density and basal corticosterone, oxytocin, and vasopressin levels were measured. Our results support the beneficial effects of adulthood EE in decreasing anxiety in males as well as promoting synaptic density in ventral hippocampal CA3. Males displayed higher levels of vasopressin while females displayed higher oxytocin, with no changes in basal corticosterone for any group after EE

    Biometric traits of Xylotrechus arvicola adults from laboratory and grape fields

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    Xylotrechus arvicola is a pest in vineyards on the Iberian Peninsula. The action of the larvae, associated to the spread of wood fungi, causes a direct and indirect damage in the crop. This article presents biometric traits of X. arvicola population adults captured in three grape fields with Protected Designation of Origin (PDO) from the Iberian Peninsula and one population of this beetle obtained in the laboratory. The aim of the study was to observe the influence of sex and environment on the size of adults. The adults showed intersexual differences for the length and width of the pronotum, the length and width of the elytra and total length. The wild females were larger than wild males and the males from grape fields were slender than wild females. The environment affected the size of the adults. The laboratory adults reached the greatest body size. The size of the adult reflects the volume of material that had been used as host where the insect had developed. The captured adults in PDO Toro, with Bush Vines Training System (BVTS) were larger than the other PDOs, leading to bigger galleries and exit holes, which could affect the structural resistance of the plant and increase pathogenic fungi infection. However, BVTS facilitates the renovation of attacked branches, which is more difficult and slower in the Bilateral Cordon Training System (BCTS)

    Ionoluminescence on α-quartz: mechanisms and modeling

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    Ionoluminescence of α - quartz exhibits two dominant emission bands peaking at 1.9 eV. (NBOHCs) and 2.7 eV (STEs. The evolution of the red emission yield does not show a correlation with the concentrations of neither the NBOHC nor with that of other color centers. The blue emission yield closely follows the amorphization kinetics independently measured by RBS/C spectrometry. A simple theoretical model has been proposed; it assumes that the formation and recombination of STEs are the primary event and both, the light emissions and the lattice structural damage are a consequence this phenomenon. The model leads to several simple mathematical equations that can be used to simulate the IL yields and provide a reasonable fit to experimental kinetic data

    The Atacama Cosmology Telescope: CO(J = 3 - 2) mapping and lens modeling of an ACT-selected dusty star-forming galaxy

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    We report Northern Extended Millimeter Array (NOEMA) CO(J=32J = 3 - 2) observations of the dusty star-forming galaxy ACT-S\,J020941+001557 at z=2.5528z = 2.5528, which was detected as an unresolved source in the Atacama Cosmology Telescope (ACT) equatorial survey. Our spatially resolved spectral line data support the derivation of a gravitational lens model from 37 independent velocity channel maps using a pixel-based algorithm, from which we infer a velocity-dependent magnification factor μ722\mu \approx 7-22 with a luminosity-weighted mean \left\approx 13. The resulting source-plane reconstruction is consistent with a rotating disk, although other scenarios cannot be ruled out by our data. After correction for lensing, we derive a line luminosity LCO(32)=(5.53±0.69)×1010Kkms1pc2L^{\prime}_{\rm CO(3-2)}= (5.53\pm 0.69) \times 10^{10}\,{\rm \,K\,km\,s^{-1}\,pc^{2}}, a cold gas mass Mgas=(3.86±0.33)×1010MM_{{\rm gas}}= (3.86 \pm 0.33) \times 10^{10}\,M_{\odot}, a dynamical mass Mdynsin2i=3.91.5+1.8×1010MM_{\rm dyn}\,{\rm sin}^2\,i = 3.9^{+1.8}_{-1.5} \times 10^{10}\,M_{\odot}, and a gas mass fraction fgascsc2i=1.00.4+0.8f_{\rm gas}\,{\rm csc}^2\,i = 1.0^{+0.8}_{-0.4}. The line brightness temperature ratio of r3,11.6r_{3,1}\approx 1.6 relative to a Green Bank Telescope CO(J=10J=1-0) detection may be elevated by a combination of external heating of molecular clouds, differential lensing, and/or pointing errors.Comment: 8 pages, 5 figures, accepted to Ap

    Refractive index changes in amorphous SiO2 (silica) by swift ion irradiation

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    The refractive index changes induced by swift ion-beam irradiation in silica have been measured either by spectroscopic ellipsometry or through the effective indices of the optical modes propagating through the irradiated structure. The optical response has been analyzed by considering an effective homogeneous medium to simulate the nanostructured irradiated system consisting of cylindrical tracks, associated to the ion impacts, embedded into a virgin material. The role of both, irradiation fluence and stopping power, has been investigated. Above a certain electronic stopping power threshold (∼2.5 keV/nm), every ion impact creates an axial region around the trajectory with a fixed refractive index (around n = 1.475) corresponding to a certain structural phase that is independent of stopping power. The results have been compared with previous data measured by means of infrared spectroscopy and small-angle X-ray scattering; possible mechanisms and theoretical models are discussed
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