We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward ...hemisphere. Restricting the momentum of the spectator protons to < 100 MeV and their angles to < 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65 < Q2 < 4.52 GeV2, with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 < x < 0.8 with little uncertainty due to nuclear effects.
Iron absorption from typical Colombian diets Pabon, M.L. (Universidad Nacional de Colombia, Bogota, Colombia); Munevar, E; Ramirez, R ...
Nutrition research (New York, N.Y.),
(Jan 1990), Volume:
10, Issue:
1
Journal Article
Peer reviewed
The availability and daily absorption of iron was determined in diets consumed by volunteers belonging to the lower-middle and lower socioeconomic strata of the Central and Oriental regions of ...Colombia. Differences in non-heme iron absorption from meals can be attributed to the content of vitamin C and to the presence of eggs. Heme iron absorption provided 38% and 56% of the total iron absorption in normal subjects from diets of the Central and Oriental regions respectively. The total iron absorption were 1.04 and 0.60 mg of iron in normal subjects consuming diets of the Central and Oriental regions, and 1.54 and 1.00 mg of iron in iron deficients. These data may be used to correlate the prevalence of iron deficiency in these populations with their respective diet and to guide fortification programs
We report the first measurement of the differential cross section on \(\phi\)-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a ...tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, \(K^+\) and \(K^-\) near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections \(\frac{d\sigma}{dt}\) for the initial photon energy from 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. This experiment establishes a baseline for a future experimental search for an exotic \(\phi\)-N bound state from heavier nuclear targets utilizing subthreshold/near-threshold production of \(\phi\) mesons.
The growth process of iron oxide nanoparticles during synthesis via the non-aqueous sol–gel method has been analyzed. Samples obtained after reaching reaction temperature
T
R
= 200 °C and during the ...following 23 h of synthesis were characterized in detail by X-ray diffraction measurements, transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, Mössbauer spectroscopy, and magnetization measurements. The results show that the iron oxide nanocrystals are majorly composed of maghemite and grow in a faceted shape. The particle size increases gradually during the synthesis, and the structural and magnetic properties improve primarily during the first 6 h of reaction.
Realistic characterization of subglacial hydrology necessitates knowledge of the range in form, scale, and spatiotemporal evolution of drainage networks. A relict subglacial meltwater corridor on the ...deglaciated Antarctic continental shelf encompasses 80 convergent and divergent channels, many of which are hundreds of meters wide and several of which lack a definable headwater source. Without significant surface‐melt contributions to the bed like similarly described landforms in the Northern Hemisphere, channelized drainage capacity varies non‐systematically by three orders of magnitude downstream. This signifies apparent additions and losses of basal water to the bed‐channelized system that relates to bed topography. Larger magnitude grounding‐line retreat events occurred while the channel system was active than once channelized drainage had ceased. Overall, this corridor demonstrates that meltwater drainage styles co‐exist in time and space in response to bed topography, with prolonged impacts on grounding‐line behavior.
Plain Language Summary
Water drainage beneath glacial ice can impact flow of the overlying ice, sediment transport underneath the ice toward the glacier's terminus, and the stability of glacial ice as it transitions from resting on the geologic terrain to floating in the ocean. Despite being an important component of glacial systems, the full range of possible modes of water delivery and how these interact and vary across time and space is not well resolved. We describe a relict subglacial meltwater network preserved on the Antarctic seafloor, representing a persistent pathway for water drainage when the East Antarctic Ice Sheet was much larger. The landforms within the drainage network implicate substantial changes in how subglacial water drainage was influenced by the shape of the underlying terrain and demonstrate the prolonged impacts that meltwater corridors have on the retreat of glacial ice.
Key Points
Bed topography was the primary control on the morphology and organization of a large paleo‐subglacial meltwater corridor in Antarctica
The morphology of the corridor supports downstream gains and losses in meltwater supply and/or changes in drainage style
Grounding‐line retreat events were significantly larger when channels were active and smaller when channelized drainage had ceased
The present work focused on synthesis and characterization of the new garnet-type materials with formula Sm3-xGdxFe5O12 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), using both the citrate and solid-state ...reaction methods. The influence of the substituting cation and the synthesis routes on the structural, morphological, and magnetic properties were evaluated by X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and 57Fe Mössbauer spectroscopy. The results showed that Gd3+ substitution allows obtaining single-phase materials, with cubic structure and space-group symmetry Ia3¯d (230). The Gd3+ substitution modified the magnetic response of the Sm3Fe5O12 garnet, generating a decrease of the saturation magnetization (Ms), coercive field (Hc), remaining magnetization (Mr), besides, the sample with x = 1.0 exhibited a Tcomp of ≈60 K. The citrate method allowed obtaining smaller particle sizes, leading to an increase of the Hc and Mr, and decreasing the Ms, this compared with the samples obtained by the solid-state reaction method. The ferrimagnetic behavior of the materials was confirmed by room temperature 57Fe Mössbauer spectroscopy, which showed the existence of magnetic hyperfine fields and Fe3+ in the different crystallographic sites. This work shows that the use of the citrate method allows obtaining garnets of high purity and with outstanding magnetic and crystalline properties, making them applicable for transformers and microwave switches production. On the other hand, the garnets were synthesized at lower temperatures (300 °C) and less time (18 h) than those used in the solid-state reaction method, decreasing the production costs.
•Sm3-xGdxFe5O12 garnets were obtained by the citrate and solid-state reaction methods.•The Gd3+ substitution allows the obtention of single-phase with x = 1.0 (33.33%).•Synthesis temperature and time were decreased 300 °C and 18 h by the citrate method.•The garnets obtained by the citrate method exhibited high Hc and Mr.
Driven by reproductive motives, male African elephants (
in musth often expand their home ranges to locate estrous females. This extended range, coupled with heightened aggression often observed in ...musth males, can be particularly problematic in regions where human-modified landscapes and elephant territories increasingly overlap. Several mitigation tools have been tested to resolve a wide range of human-elephant conflicts with varying degrees of success due to geographical disparities and habituation. We present findings on the potential application of estrous call playbacks in manipulating the behavior and movement of male elephants non-invasively, particularly mature musth adults and younger post-dispersal males, in Etosha National Park. Estrous vocalizations were presented across 26 experimental trials to mature musth adults (
= 5), mature non-musth adults (
= 6), and non-musth males belonging to younger, post-dispersal age classes (
= 8), with behavioral responses scored on a gradient scale from 0-1. Both mature musth adults and younger non-musth elephants were significantly more likely to respond with the highest intensity by approaching the acoustic source compared to mature non-musth adults that avoided the call. However, younger males tested in the presence of an older, higher-ranking male tended to react with a lower intensity than those tested alone. This result likely demonstrates the influence of social hierarchy and associations on male elephant behavior. We also observed a significant increase in physiological response, measured by defecation rate, across all male groups in response to the estrous call playbacks. Our findings suggest that using estrous calls as acoustic deterrents may effectively and non-invasively aid in reducing tension at the human-elephant interface, depending on the age, social context, and reproductive status of the male elephant.
We present a systematic study of structural and magnetic properties of LaBa1-xSrxCuFeO5+δ (La-x) and YbBa1-xSrxCuFeO5+δ (Yb-x) (x = 0.0, 0.25 and 0.5) ceramic compounds, synthesized with solid-state ...method. X-ray powder diffraction (XRD) technique indicates that La-x and Yb-x systems present single phases consistent with an orthorhombic symmetry (space group Immm (71)) and tetragonal symmetries (space group P4mm (99)), respectively, and a decreasing lattice parameter as the content of Sr increases. The results of infrared spectrums show the typical energy bands of a perovskite with a layered structure, and surface morphologic analysis evidenced the formation of polycrystalline material with diverse grain shape. The compositional characterization, obtained via the energy-dispersive X-ray spectroscopy technique, suggests that we achieve the desired material stoichiometry with the absence of impurities. Finally, vibrating sample magnetometry measurements evidenced an antiferromagnetic transition at a temperature around the 160 K only for x = 0, which is attributed to the dominant magnetic moments of rare earth ions.
•LaBa1-xSrxCuFeO5+δ and YbBa1-xSrxCuFeO5+δ systems were obtained by the solid-state method.•The RE3+ and Sr2+ substitution allows the obtention of single-phase.•The surface morphologic study showed the formation of polycrystalline material with diverse shape of grains 0.76 μm mean size.•The compounds evidenced an antiferromagnetic transition at a temperature around the 160 K only for x = 0.
Neural response properties that typify primary sensory afferents are critical to fully appreciate because they establish and, ultimately represent, the fundamental coding design used for higher-level ...processing. Studies illuminating the center-surround receptive fields of retinal ganglion cells, for example, were ground-breaking because they determined the foundation of visual form detection. For the auditory system, a basic organizing principle of the spiral ganglion afferents is their extensive electrophysiological heterogeneity establishing diverse intrinsic firing properties in neurons throughout the spiral ganglion. Moreover, these neurons display an impressively large array of neurotransmitter receptor types that are responsive to efferent feedback. Thus, electrophysiological diversity and its neuromodulation are a fundamental encoding mechanism contributed by the primary afferents in the auditory system. To place these features into context, we evaluated the effects of hyperpolarization and cAMP on threshold level as indicators of overall afferent responsiveness in CBA/CaJ mice of either sex. Hyperpolarization modified threshold gradients such that distinct voltage protocols could shift the relationship between sensitivity and stimulus input to reshape resolution. This resulted in an "accordion effect" that appeared to stretch, compress, or maintain responsivity across the gradient of afferent thresholds. cAMP targeted threshold and kinetic shifts to rapidly adapting neurons, thus revealing multiple cochleotopic properties that could potentially be independently regulated. These examples of dynamic heterogeneity in primary auditory afferents not only have the capacity to shift the range, sensitivity, and resolution, but to do so in a coordinated manner that appears to orchestrate changes with a seemingly unlimited repertoire.
How do we discriminate the more nuanced qualities of the sound around us? Beyond the basics of pitch and loudness, aspects, such as pattern, distance, velocity, and location, are all attributes that must be used to encode acoustic sensations effectively. While higher-level processing is required for perception, it would not be unexpected if the primary auditory afferents optimized receptor input to expedite neural encoding. The findings reported herein are consistent with this design. Neuromodulation compressed, expanded, shifted, or realigned intrinsic electrophysiological heterogeneity to alter neuronal responses selectively and dynamically. This suggests that diverse spiral ganglion phenotypes provide a rich substrate to support an almost limitless array of coding strategies within the first neural element of the auditory pathway.
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