4,101 research outputs found

    Multilayered printed circuit boards inspected by X-ray laminography

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    Technique produces high resolution cross-sectional radiographs with close interplane spacing for inspecting multilayer boards to be used in providing circuitry routing and module structural support

    Geochemical assessment of the degree of isolation of edge-of-aquifer groundwater along a fringe of the southern High Plains Aquifer, USA

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    © 2019, The Author(s). The edge of regional aquifers can be complex hydrodynamic systems with unique flow dynamics, water quality, and continuity relationships with the main aquifer system. A site near the southwestern margin of the High Plains Aquifer (USA) was investigated to characterize the local hydrogeology and its relationship with the regional aquifer system. Measurements of tritium, ion concentrations, oxygen and hydrogen isotopes, and hydraulic heads documented (1) a discontinuous saturated zone, (2) no inflow to the study area from the regional aquifer, (3) focused recharge beneath playas with limited local mixing between pockets of saturation, (4) outflow orthogonal to the regional aquifer flow direction, (5) localized multi-year reversals in flow direction following high precipitation events, and (6) a magnified influence of the paleo-erosional surface of the basement rock (Dockum Group) on groundwater isolation and flow direction. In isolated areas, groundwater can be trapped on decadal time scales by depressions in the Dockum, or by recharge events that periodically reverse groundwater gradients

    Dehiscence of detached internal limiting membrane in eyes with myopic traction maculopathy with spontaneous resolution

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    Background: Idjwi, an island of approximately 220,000 people, is located in eastern DRC and functions semi-autonomously under the governance of two kings (mwamis). At more than 8 live births per woman, Idjwi has one of the highest total fertility rates (TFRs) in the world. Rapid population growth has led to widespread environmental degradation and food insecurity. Meanwhile family planning services are largely unavailable.Methods: At the invitation of local leaders, we conducted a representative survey of 2,078 households in accordance with MEASURE DHS protocols, and performed ethnographic interviews and focus groups with key informants and vulnerable subpopulations. Modelling proximate determinates of fertility, we evaluated how the introduction of contraceptives and/or extended periods of breastfeeding could reduce the TFR.Results: Over half of all women reported an unmet need for spacing or limiting births, and nearly 70% named a specific modern method of contraception they would prefer to use; pills (25.4%) and injectables (26.5%) were most desired. We predicted that an increased length of breastfeeding (from 10 to 21 months) or an increase in contraceptive prevalence (from 1% to 30%), or a combination of both could reduce TFR on Idjwi to 6, the average desired number of children. Increasing contraceptive prevalence to 15% could reduce unmet need for contraception by 8%.Conclusions: To meet women’s need and desire for fertility control, we recommend adding family planning services at health centers with NGO support, pursuing a community health worker program, promoting extended breastfeeding, and implementing programs to end sexual- and gender-based violence toward women

    The Fornax Spectroscopic Survey I. Survey Strategy and Preliminary Results on the Redshift Distribution of a Complete Sample of Stars and Galaxies

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    The Fornax Spectroscopic Survey will use the Two degree Field spectrograph (2dF) of the Anglo-Australian Telescope to obtain spectra for a complete sample of all 14000 objects with 16.5<=Bj<=19.7 in a 12 square degree area centred on the Fornax Cluster. By selecting all objects---both stars and galaxies---independent of morphology, we cover a much larger range of surface brightness and scale size than previous surveys. In this paper we present results from the first 2dF field. Redshift distributions and velocity structures are shown for all observed objects in the direction of Fornax, including Galactic stars, galaxies in and around the Fornax Cluster, and for the background galaxy population. The velocity data for the stars show the contributions from the different Galactic components, plus a small tail to high velocities. We find no galaxies in the foreground to the cluster in our 2dF field. The Fornax Cluster is clearly defined kinematically. The mean velocity from the 26 cluster members having reliable redshifts is 1560+/-80 km/s. They show a velocity dispersion of 380+/-50 km/s. Large-scale structure can be traced behind the cluster to a redshift beyond z=0.3. Background compact galaxies and low surface brightness galaxies are found to follow the general galaxy distribution.Comment: LaTeX format; uses aa.cls (included). Accepted for publication in Astronomy and Astrophysic

    Effects of a large-scale, natural sediment deposition event on plant cover in a Massachusetts salt marsh

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    In mid-winter 2018, an unprecedented sediment deposition event occurred throughout portions of the Great Marsh in Massachusetts. Evaluation of this event in distinct marsh areas spanning three towns (Essex, Ipswich, and Newbury) revealed deposition covering 29.2 hectares with an average thickness of 30.1±2.1 mm measured shortly after deposition. While sediment deposition helps marshes survive sea level rise by building elevation, effects of such a large-scale deposition on New England marshes are unknown. This natural event provided an opportunity to study effects of large-scale sediment addition on plant cover and soil chemistry, with implications for marsh resilience. Sediment thickness did not differ significantly between winter and summer, indicating sediment is not eroding or compacting. The deposited sediment at each site had similar characteristics to that of the adjacent mudflat (e.g., texture, bivalve shells), suggesting that deposited materials resulted from ice rafting from adjacent flats, a natural phenomenon noted by other authors. Vegetative cover was significantly lower in plots with rafted sediment (75.6±2.3%) than sediment-free controls (93.1±1.6%) after one growing season. When sorted by sediment thickness categories, the low thickness level (1–19 mm) had significantly greater percent cover than medium (20–39 mm) and high (40–90 mm) categories. Given that sediment accretion in the Great Marsh was found to average 2.7 mm per year, the sediment thickness documented herein represents ~11 years of sediment accretion with only a 25% reduction in plant cover, suggesting this natural sediment event will likely increase long-term marsh resilience to sea level rise

    Age-related neurochemical changes in the rhesus macaque inferior colliculus

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    Age-related hearing loss (ARHL) is marked by audiometric hearing deficits that propagate along the auditory pathway. Neurochemical changes as a function of aging have also been identified in neurons along the auditory pathway in both rodents and carnivores, however, very little is known about how these neurochemicals change in the non-human primate. To examine how these compensatory neurochemical changes relate to normal aging and audiometric sensitivity along the auditory pathway, we collected auditory brainstem responses (ABRs) and brain specimens from seven rhesus monkeys spanning in age from 15 to 35 years old, and examined the relationship between click evoked ABR thresholds and the ABR evoked pure tone average (PTA) and changes in the number of parvalbumin and NADPH-diaphorase positive cells in the auditory midbrain. We found that the number of parvalbumin positive cells in the central nucleus and the surrounding cortex regions of the inferior colliculus were strongly correlated with advancing age and ABR PTA. We also found that the numbers of NADPHd positive cells in these same regions were not associated with normal aging or changes in the ABR thresholds. These findings suggest that the auditory midbrain undergoes an up-regulation of parvalbumin expressing neurons with aging that is related to changes in the processing of frequencies across the audiometric range

    Implications of Dramatic Broad Absorption Line Variability in the Quasar FBQS J1408+3054

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    We have observed a dramatic change in the spectrum of the formerly heavily absorbed `overlapping-trough' iron low-ionization broad absorption line (FeLoBAL) quasar FBQS J1408+3054. Over a time span of between 0.6 to 5 rest-frame years, the Mg II trough outflowing at 12,000 km/s decreased in equivalent width by a factor of two and the Fe II troughs at the same velocity disappeared. The most likely explanation for the variability is that a structure in the BAL outflow moved out of our line of sight to the ultraviolet continuum emitting region of the quasar's accretion disk. Given the size of that region, this structure must have a transverse velocity of between 2600 km/s and 22,000 km/s. In the context of a simple outflow model, we show that this BAL structure is located between approximately 5800 and 46,000 Schwarzschild radii from the black hole. That distance corresponds to 1.7 to 14 pc, 11 to 88 times farther from the black hole than the H-beta broad-line region. The high velocities and the parsec-scale distance for at least this one FeLoBAL outflow mean that not all FeLoBAL outflows can be associated with galaxy-scale outflows in ultraluminous infrared galaxies transitioning to unobscured quasars. The change of FBQS J1408+3054 from an FeLoBAL to a LoBAL quasar also means that if (some) FeLoBAL quasars have multiwavelength properties which distinguish them from HiBAL quasars, then some LoBAL quasars will share those properties. Finally, we extend previous work on how multiple-epoch spectroscopy of BAL and non-BAL quasars can be used to constrain the average lifetime of BAL episodes (currently >60 rest-frame years at 90% confidence).Comment: Final version to appear in MNRAS: references added and factor of 2 underestimate of accretion disk size corrected, resulting in absorber constrained to be somewhat closer to the black hole. For an animated gif showing the spectral evolution of the broad absorption line troughs in this quasar, see http://www.yorku.ca/phall/film19952009.gi

    Total knee arthroplasty using computer-assisted navigation in patients with deformities of the femur and tibia: A report of 5 cases

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    Anatomic aberrations of the femur and tibia secondary to trauma, congenital defects, and prior surgery present challenges for the reconstructive knee surgeon because of an altered mechanical axis and distorted anatomic landmarks. Five patients with arthritis of the knee and extra-articular femoral and/or tibial deformity, retained hardware, or intramedullary (IM) implants underwent total knee arthroplasty using a computer navigation system. The navigation system obviated the need for an IM guide, and the normal mechanical axis of the patients was restored. Extensive dissection for hardware removal or osteotomy was not necessary in these patients. In these 5 cases, a navigation system proved to be an effective tool for restoration of limb alignment in the presence of significant extra-articular deformities and/or IM hardware. Thus, it provides an alternative approach to the traditional IM instrumentation for treating these patients in an effective manner
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