3,436 research outputs found

    Dietary variations in three co-occurring rockfish species off the Pacific Northwest during anomalous oceanographic events in 1998 and 1999

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    Stomach samples from three rockfish species, yellowtail (Sebastes f lavidus), widow (S. entomelas), and canary (S. pinniger) rockfish, seasonally collected off the Pacific Northwest in 1998 and 1999, provided quantitative information on the food habits of these species during and after the 1997–98 El Niño event. Although euphausiids were the most common major prey of all three predators, gelatinous zooplankton and fishes were the most commonly consumed prey items during some seasonal quarters. The influence of the El Niño event was evident in the diets. Anomalous prey items, including the southern euphausiid species Nyctiphanes simplex and juveniles of Pacific whiting (Merluccius productus) frequently appeared in the diets in the spring and summer of 1998. The results of stomach contents analyses, based on 905 stomach samples from 49 trawl hauls during seven commercial fishing trips and from 56 stations during research surveys, were consistent with the timing of occurrence and the magnitude of change in biomass of some zooplankton species reported from zooplankton studies in the northern California Current during the 1997–98 El Niño. Our findings indicate that the observed variations of prey groups in some rockfish diets may be a function of prey variability related to climate and environment changes

    Design, modeling, and analysis of multi-channel demultiplexer/demodulator

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    Traditionally, satellites have performed the function of a simple repeater. Newer data distribution satellite architectures, however, require demodulation of many frequency division multiplexed uplink channels by a single demultiplexer/demodulator unit, baseband processing and routing of individual voice/data circuits, and remodulation into time division multiplexed (TDM) downlink carriers. The TRW MCDD (Multichannel Demultiplexer/Multirate Demodulator) operates on a 37.4 MHz composite input signal. Individual channel data rates are either 64 Kbps or 2.048 Mbps. The wideband demultiplexer divides the input signal into 1.44 MHz segments containing either a single 2.048 Mbps channel or thirty two 64 Kbps channels. In the latter case, the narrowband demultiplexer further divides the single 1.44 MHz wideband channel into thirty two 45 KHz narrowband channels. With this approach the time domain Fast Fourier Transformation (FFT) channelizer processing capacity is matched well to the bandwidth and number of channels to be demultiplexed. By using a multirate demodulator fewer demodulators are required while achieving greater flexibility. Each demodulator can process a wideband channel or thirty two narrowband channels. Either all wideband channels, a mixture of wideband and narrowband channels, or all narrowband channels can be demodulated. The multirate demodulator approach also has lower nonrecurring costs since only one design and development effort is needed. TRW has developed a proof of concept (POC) model which fully demonstrates the signal processing fuctions of MCDD. It is capable of processing either three 2.048 Mbps channels or two 2.048 Mbps channels and thirty two 64 Kbps channels. An overview of important MCDD system engineering issues is presented as well as discussion on some of the Block Oriented System Simulation analyses performed for design verification and selection of operational parameters of the POC model. Systems engineering analysis of the POC model confirmed that the MCDD concepts are not only achievable but also balance the joint goals of minimizing on-board complexity and cost of ground equipment, while retaining the flexibility needed to meet a wide range of system requirements

    People, Land, and Profit in the South of Market: A Critical Analysis of the Central SoMa Plan

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    The South of Market neighborhood in San Francisco has undergone several transformations, especially since WWII, that have largely characterized the broader relationships among local city government, private interests, and the public in San Francisco. These transformations have included deindustrialization and the restructuring of the local economy after WWII, Urban Renewal, the intensification of office uses, and the first and second technology booms. City planning and the implementation of area plans (a type of city planning development tool) have also played a significant role in facilitating these changes. By historically situating the current moment in San Francisco, this research paper seeks to better understand the role of planning in facilitating these changes during this current moment of tremendous wealth in San Francisco, ushered in by a second technology boom. Specifically, this research paper seeks to critically analyze the neighborhood area plan, the Central SoMa Plan, and speculate on the possible impacts of the plan. Based on the history of development and change in the South of Market, and a review of existing area plans, the argument is made that the changes proposed in the Central SoMa Plan work to actively restructure the neighborhood in order to allow for high- end development at the expense of existing working class residents, low-income communities, and blue-collar jobs

    Two Conditions for Galaxy Quenching: Compact Centres and Massive Haloes

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    We investigate the roles of two classes of quenching mechanisms for central and satellite galaxies in the SDSS (z<0.075z<0.075): those involving the halo and those involving the formation of a compact centre. For central galaxies with inner compactness ÎŁ1kpc∌109−9.4M⊙kpc−2\Sigma_{\rm 1kpc} \sim 10^{9-9.4}M_{\odot} {\rm kpc}^{-2}, the quenched fraction fqf_{q} is strongly correlated with ÎŁ1kpc\Sigma_{\rm 1kpc} with only weak halo mass MhM_{\rm h} dependence. However, at higher and lower ÎŁ1kpc\Sigma_{\rm 1kpc}, sSFR is a strong function of MhM_{\rm h} and mostly independent of ÎŁ1kpc\Sigma_{\rm 1kpc}. In other words, ÎŁ1kpc∌109−9.4M⊙kpc−2\Sigma_{\rm 1kpc} \sim 10^{9-9.4} M_{\odot} {\rm kpc}^{-2} divides galaxies into those with high sSFR below and low sSFR above this range. In both the upper and lower regimes, increasing MhM_{\rm h} shifts the entire sSFR distribtuion to lower sSFR without a qualitative change in shape. This is true even at fixed M∗M_{*}, but varying M∗M_{*} at fixed MhM_{\rm h} adds no quenching information. Most of the quenched centrals with Mh>1011.8M⊙M_{\rm h} > 10^{11.8}M_{\odot} are dense (ÎŁ1kpc>109 M⊙kpc−2\Sigma_{\rm 1kpc} > 10^{9}~ M_{\odot} {\rm kpc}^{-2}), suggesting compaction-related quenching maintained by halo-related quenching. However, 21% are diffuse, indicating only halo quenching. For satellite galaxies in the outskirts of halos, quenching is a strong function of compactness and a weak function of host MhM_{\rm h}. In the inner halo, MhM_{\rm h} dominates quenching, with ∌90%\sim 90\% of the satellites being quenched once Mh>1013M⊙M_{\rm h} > 10^{13}M_{\odot}. This regional effect is greatest for the least massive satellites. As demonstrated via semi-analytic modelling with simple prescriptions for quenching, the observed correlations can be explained if quenching due to central compactness is rapid while quenching due to halo mass is slow.Comment: 16 pages, 11 figures, MNRAS accepte

    Web based lecture technologies: blurring the boundaries between face to face and distance learning

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    Web based lecture technologies (WBLT) have gained popularity amongst universities in Australia as a tool for delivering lecture recordings to students in close to real time. This paper reports on a selection of results from a larger research project investigating the impact of WBLT on teaching and learning. Results show that while staff see the advantages for external students, they question the extent to which these advantages apply to internal students. In contrast both cohorts of students were positive about the benefits of the technologies for their learning and they adopted similar strategies for their use. With the help of other technologies, some external students and staff even found WBLT useful for fostering communication between internal and external students. As such, while the traditional boundary between internal and external students seems to remain for some staff, students seem to find the boundary much less clear

    Factors Affecting Outcomes Of Second Intent Healing Of Nasal Defects After Mohs Micrographic Surgery

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    Background: Reconstruction of nasal defects secondary to Mohs micrographic surgery (MMS) presents particular challenges related to the complex topography, skin quality, tissue laxity and functional and aesthetic concerns of the region. Factors affecting outcomes resulting from second intent healing (SIH) on the nose have not been well described. Purpose: The purpose of the study was to identify factors impacting outcomes of SIH for nasal tumors following MMS.Methods: Retrospective analysis was performed of all nasal lesions treated with MMS followed by SIH from a single surgical center over a 1.5-year period. Ninety-six cases were included. Chart review was performed, and data was collected including age, gender, nasal site, tumor type, defect size, depth and number of MMS stages. Pre- and post-operative follow-up photographs were available for all cases. All five authors evaluated the photographs using the modified Manchester scar scale. Analysis was then conducted to identify features associated with good outcomes. Results: Of the 96 tumors, thirty-nine lesions (40.6%) were located on the nasal tip (including supratip), 32 (33.3%) on the ala/alar groove, 17 (17.7%) on the sidewall, and eight (8.3%) on the dorsum. The average defect size was 0.83cm2 (diameter of 1.06 centimeters ± 0.4). Defect diameter and defect depth were the factors that significantly impacted scar outcome (p\u3c0.001) in multivariate analysis. No significant functional deficits were reported. Conclusion: This retrospective study suggests that nasal defects with area less than 0.83cm2 (or 1.06 cm diameter) and depth of defect not extending beyond the superficial fat healed well by SIH regardless of location on the nose

    Early-Life Air Pollution Exposure, Neighborhood Poverty, and Childhood Asthma in the United States, 1990⁻2014.

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    Ambient air pollution is a well-known risk factor of various asthma-related outcomes, however, past research has often focused on acute exacerbations rather than asthma development. This study draws on a population-based, multigenerational panel dataset from the United States to assess the association of childhood asthma risk with census block-level, annual-average air pollution exposure measured during the prenatal and early postnatal periods, as well as effect modification by neighborhood poverty. Findings suggest that early-life exposures to nitrogen dioxide (NO₂), a marker of traffic-related pollution, and fine particulate matter (PM2.5), a mixture of industrial and other pollutants, are positively associated with subsequent childhood asthma diagnosis (OR = 1.25, 95% CI = 1.10⁻1.41 and OR = 1.25, 95% CI = 1.06⁻1.46, respectively, per interquartile range (IQR) increase in each pollutant (NO₂ IQR = 8.51 ppb and PM2.5 IQR = 4.43 ”/mÂł)). These effects are modified by early-life neighborhood poverty exposure, with no or weaker effects in moderate- and low- (versus high-) poverty areas. This work underscores the importance of a holistic, developmental approach to elucidating the interplay of social and environmental contexts that may create conditions for racial-ethnic and socioeconomic disparities in childhood asthma risk

    Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements

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    Aim: This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements. Materials and methods: A total of 80 ceramic veneer disks were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These disks were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into four subgroups, based on ceramic disk thickness (0.3, 0.6, 0.9, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm2) with respect to microhardness and degree of conversion was statistically evaluated by using analysis of variance (ANOVA). Results: For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (p \u3c 0.05). For the MH values between LC and DC resin cement groups, there was statistically significant difference (p \u3c 0.05); overall, the MH values of LC resin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (p \u3c 0.05). However, among the LC subgroups, there was no statistically significant difference among them (p \u3e 0.05). Conclusion: The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup. Clinical Significance: While clinically adequate polymerization of LC resin cement can be achieved with a maximum 1.2 mm of porcelain veneer restoration, the increase of curing time or light intensity is clinically needed for DC resin cements at the thickness of more than 0.9 mm

    Patching and the p-adic local Langlands correspondence

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    We use the patching method of Taylor--Wiles and Kisin to construct a candidate for the p-adic local Langlands correspondence for GL_n(F), F a finite extension of Q_p. We use our construction to prove many new cases of the Breuil--Schneider conjecture.Comment: Final version, to appear in Cambridge Journal of Mathematic
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