303 research outputs found
Mapping of the Quasi-Periodic Oscillations at the Flank Magnetopause into the Ionosphere
We have estimated the ionospheric location, area, and travel time of quasi-periodic oscillations originating from the magnetospheric flanks. This was accomplished by utilizing global and local MHD models and Tsyganenko semi-empirical magnetic field model on multiple published and four new cases believed to be caused by the Kelvin– Helmholtz Instability. Finally, we used auroral, magnetometer, and radar instruments to observe the ionospheric signatures. The ionospheric magnetic latitude determined using global MHD and Tsyganenko models ranged from 58.3–80.2 degrees in the Northern Hemisphere and −59.6 degrees to −83.4 degrees in the Southern Hemisphere. The ionospheric magnetic local time ranged between 5.0–13.8 h in the Northern Hemisphere and 1.3–11.9 h in the Southern Hemisphere. Typical Alfvén wave travel time from spacecraft location to the closest ionosphere ranged between 0.6–3.6 min. The projected ionospheric size calculated at an altitude of 100 km ranged from 47–606 km, the same order of magnitude as previously determined ionospheric signature sizes. Stationary and traveling convection vortices were observed in SuperDARN radar data in both hemispheres. The vortices were between 1000–1800 km in size. Some events were located within the ionospheric footprint ranges. Pc5 magnetic oscillations were observed in SuperMAG magnetometer data in both hemispheres. The oscillations had periods between 4– 10 min with amplitudes of 3–25 nT. They were located within the ionospheric footprint ranges. Some ground magnetometer data power spectral density peaked at frequencies within one tenth of a mHz of the peaks found in the corresponding Cluster data. These magnetometer observations were consistent with previously published results
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Cross-platform validation of notional baseline architecture models of naval electric ship power systems
To support efforts in assessing the relative merit of alternative power system architectures for future naval combatants, the Electric Ship Research and Development Consortium (ESRDC) has developed notional baseline models for each of the primary candidate architectures currently considered, medium-voltage DC (MVDC), conventional 60 Hz medium-voltage (MVAC), and high-frequency medium-voltage (HFAC). Initial efforts have focused on the development of a consistent set of component models, of which the system models can be comprised, and the basic definition of the system models. The broader objectives of the consortium, however, go beyond the definition of the baseline models. The focus is on the process by which the models are implemented in software and validated, the process by which the performance of the disparate system models are objectively and quantitatively assessed and compared, and, ultimately, the process by which the relative merits of the architectures may be assessed. This paper focuses specifically on cross-platform component validation.Center for Electromechanic
Cluster Observations of a Cusp Diamagnetic Cavity: Structure, Size, and Dynamics
We have analyzed Cluster magnetic field and plasma data during high‐altitude cusp crossing and compared them with high‐resolution MHD simulations. Cluster encountered a diamagnetic cavity (DMC) during northward interplanetary magnetic field (IMF) conditions, and as the IMF rotated southward, the spacecraft reencountered the cavity more at the sunward side of the cusp because the reconnection site had changed location. We found evidence of magnetic reconnection both during northward and southward IMF conditions. The Cluster separation was ∼5000 km, enabling for the first time measurements both inside the DMC and surrounding boundaries that allowed us to construct the structure of the DMC and put the observations of ion pitch angle distributions in context of local reconnection topology and gradients of the boundaries. The cavity is characterized by strong magnetic field fluctuations and high‐energy particles. At the magnetosheath boundary the high‐energy particle fluxes reduced by several orders of magnitude. Throughout the magnetosheath, the high‐energy proton fluxes remained low except during brief intervals when sc4 and sc1 dropped back into the cavity due to changes in solar wind dynamic pressure. However, the high‐energy O+ fluxes did not drop as much in the magnetosheath and were mostly at 60°–120° pitch angles, indicative of a trapped population in the DMC which is observed in the magnetosheath due to a large gyroradius. Significant fluxes of protons and ionized oxygen were also observed escaping from the diamagnetic cavity antiparallel to the magnetic field in a time scale more consistent with the local DMC source than with a reflected bow shock source
Molecular Structure of Polystyrene at Air/Polymer and Solid/Polymer Interfaces
IR-visible sum-frequency generation(SFG) spectroscopy has been used in a total internal reflection geometry to study the molecular structure of polystyrene (PS) at PS/sapphire and PS/air interfaces, simultaneously. The symmetric vibrational modes of the phenyl rings dominate the SFG spectra at the PS/air interface as compared to the antisymmetric vibrational modes at the PS/sapphire interface. This indicates approximately parallel orientation of the phenyl rings at the PS/air interface while nearly perpendicular orientation at the PS/sapphire interface, with respect to the surface normal
Immunogenicity of vaccination against influenza, Streptococcus pneumoniae and Haemophilus influenzae type B in patients with multiple myeloma
Vaccination against influenza and Streptococcus pneumoniae is recommended for elderly and immunocompromised individuals. However, there is little information concerning the efficacy of vaccination in specific groups of patients. In this study, 52 patients underwent vaccination against influenza, S. pneumoniae and Haemophilus influenzae type b (Hib) as they attended hospital outpatient clinics. Serum was analysed prior to vaccination and 4–6 weeks afterwards. Antibody titres against S. pneumoniae and Hib were compared with reference values corresponding to the geometric mean titres of a healthy UK population. For influenza vaccination, haemagglutination inhibition (HI) titres were measured against three inactivated strains; a titre of ≥ 1/40 was considered protective. No patient had protective titres to all three antigens prior to vaccination and 41 patients (85%) had titres < 1/40 to all 3 strains. Post vaccination only 9/48 patients (19%) achieved protective antibody titres. Resistance to S. pneumoniae and response to Pneumovax II was also poor: prevaccination, 45 patients (93%) had suboptimal antibody titres and in 26/43 patients (61%) titres remained low post vaccination. Resistance to Hib and response to vaccination was comparable with the healthy adult UK population. These results question the practice of routine influenza and pneumococcal vaccination in myeloma patients. © 2000 Cancer Research Campaig
Impact of COVID-19 on primary care contacts with children and young people in England: longitudinal trends study 2015–2020
BACKGROUND: The NHS response to COVID-19 altered provision and access to primary care. AIM: To examine the impact of COVID-19 on GP contacts with children and young people (CYP) in England. DESIGN AND SETTING: A longitudinal trends analysis was undertaken using electronic health records from the Clinical Practice Research Datalink (CPRD) Aurum database. METHOD: All CYP aged 90%). Remote contacts more than doubled, increasing most in infants (over 2.5-fold). Total contacts for respiratory illnesses fell by 74% whereas contacts for common non-transmissible conditions shifted largely to remote contacts, mitigating the total fall (31%). CONCLUSION: During the COVID-19 pandemic, CYP's contact with GPs fell, particularly for face-to-face assessments. This may be explained by a lower incidence of respiratory illnesses because of fewer social contacts and changing health-seeking behaviour. The large shift to remote contacts mitigated total falls in contacts for some age groups and for common non-transmissible conditions
Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud - IV. Evidence for multiple populations in Hodge 11 and NGC 2210
We present a multiple population search in two old Large Magellanic Cloud (LMC) Globular clusters, Hodge 11 and NGC 2210. This work uses data from the Advanced Camera for Surveys and Wide Field Camera 3 on the Hubble Space Telescope from programme GO- 14164 in Cycle 23. Both of these clusters exhibit a broadened main sequence with the second population representing (20±~5) per cent forNGC2210 and (30±~5) per cent forHodge 11. In both clusters, the smaller population is redder than the primary population, suggesting CNO variations. Hodge 11 also displays a bluer second population in the horizontal branch, which is evidence for helium enhancement. However, even though NGC 2210 shows similarities to Hodge 11 in the main sequence, there does not appear to be a second population on NGC 2210's horizontal branch. This is the first photometric evidence that ancient LMC Globular clusters exhibit multiple stellar populations.Fil: Gilligan, Christina K.. Dartmouth College; Estados UnidosFil: Chaboyer, Brian. Dartmouth College; Estados UnidosFil: Cummings, Jeffrey D.. University Johns Hopkins; Estados UnidosFil: Mackey, Dougal. Australian National University. Research School of Astronomy & Astrophysics; AustraliaFil: Cohen, Roger E.. Space Telescope Science Institute; Estados UnidosFil: Geisler, Douglas. Universidad de La Serena; ChileFil: Grocholski, Aaron J.. University of Washington; Estados UnidosFil: Parisi, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Sarajedini, Ata. University of Florida; Estados UnidosFil: Ventura, Paolo. Osservatorio Astronomico Di Roma; ItaliaFil: Villanova, Sandro. Universidad de Concepción; ChileFil: Yang, Soung-Chul. Korea Astronomy And Space Science Institute; Corea del SurFil: Wagner-Kaiser, Rachel. University of Florida; Estados Unido
Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud - V. Multiple populations in ancient globular clusters
We examine four ancient LargeMagellanic Cloud (LMC) globular clusters (GCs) for evidence of multiple stellar populations using the Advanced Camera for Surveys andWide Field Camera 3 on the Hubble Space Telescope Programme GO-14164. NGC 1466, NGC 1841, and NGC 2257 all show evidence for a redder, secondary population along themain sequence. Reticulum does not showevidence for the presence of a redder population, but thisGChas the least number of stars and Monte Carlo simulations indicate that the sample of main-sequence stars is too small to robustly infer whether a redder population exists in this cluster. The second, redder, population of the other three clusters constitutes ∼ 30 - 40 per cent of the total population along the main sequence. This brings the total number of ancient LMC GCs with known split or broadened main sequences to five. However, unlike for Hodge 11 and NGC 2210 (see Gilligan et al. (2019)), none of the clusters shows evidence for multiple populations in the horizontal branch. We also do not find evidence of a second population along the red giant branch.Fil: Gilligan, Christina K.. Dartmouth College; Estados UnidosFil: Chaboyer, Brian. Dartmouth College; Estados UnidosFil: Cummings, Jeffrey D.. University Johns Hopkins; Estados UnidosFil: Mackey, Dougal. Australian National University; AustraliaFil: Cohen, Roger E.. Space Telescope Science Institute; Estados UnidosFil: Geisler, Douglas. Universidad de Concepción; ChileFil: Grocholski, Aaron J.. University of Florida; Estados UnidosFil: Parisi, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Sarajedini, Ata. University of Florida; Estados UnidosFil: Ventura, Paolo. Osservatorio Astronomico Di Roma; ItaliaFil: Villanova, Sandro. Universidad de Concepción; ChileFil: Yang, Soung-Chul. Korea Astronomy And Space Science Institute; Corea del SurFil: Wagner-Kaiser, Rachel. University of Florida; Estados Unido
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