162 research outputs found
The Fermi Bubbles. I. Possible Evidence for Recent AGN Jet Activity in the Galaxy
The Fermi Gamma-ray Space Telescope reveals two large gamma-ray bubbles in
the Galaxy, which extend about 50 degrees (~ 10 kpc) above and below the
Galactic center (GC) and are symmetric about the Galactic plane. Using
axisymmetric hydrodynamic simulations with a self-consistent treatment of the
dynamical cosmic ray (CR) - gas interaction, we show that the bubbles can be
created with a recent active galactic nucleus (AGN) jet activity about 1 - 3
Myr ago, which was active for a duration of ~ 0.1 - 0.5 Myr. The bipolar jets
were ejected into the Galactic halo along the rotation axis of the Galaxy. Near
the GC, the jets must be moderately light with a typical density contrast 0.001
<~ \eta <~ 0.1 relative to the ambient hot gas. The jets are energetically
dominated by kinetic energy, and over-pressured with either CR or thermal
pressure which induces lateral jet expansion, creating fat CR bubbles as
observed. The sharp edges of the bubbles imply that CR diffusion across the
bubble surface is strongly suppressed. The jet activity induces a strong shock,
which heats and compresses the ambient gas in the Galactic halo, potentially
explaining the ROSAT X-ray shell features surrounding the bubbles. The Fermi
bubbles provide plausible evidence for a recent powerful AGN jet activity in
our Galaxy, shedding new insights into the origin of the halo CR population and
the channel through which massive black holes in disk galaxies release feedback
energy during their growth.Comment: Revised version, accepted for publication in ApJ. 17 pages, 11
figure
Superconducting resonators with voltage-controlled frequency and nonlinearity
Voltage-tunable superconductor-semiconductor devices offer a unique platform
to realize dynamic tunability in superconducting quantum circuits. By
galvanically connecting a gated InAs-Al Josephson junction to a coplanar
waveguide resonator, we demonstrate the use of a wide-range gate-tunable
superconducting element. We show that the resonant frequency is controlled via
a gate-tunable Josephson inductance and that the non-linearity of the
voltage-controlled InAs-Al junction is non-dissipative as is the case with
conventional Al-AlO junctions. As the gate voltage is decreased, the
inductive participation of the junction increases up to , resulting in
the resonant frequency being tuned by over 2 GHz. Utilizing the wide tunability
of the device, we demonstrate that two resonant modes can be adjusted such that
they strongly hybridize, exhibiting an avoided level crossing with a coupling
strength of 51 MHz. Implementing such voltage-tunable resonators is the first
step toward realizing wafer-scale continuous voltage control in superconducting
circuits for qubit-qubit coupling, quantum-limited amplifiers, and quantum
memory platforms
Quasiparticle dynamics in epitaxial Al-InAs planar Josephson junctions
Quasiparticle (QP) effects play a significant role in the coherence and
fidelity of superconducting quantum circuits. The Andreev bound states of high
transparency Josephson junctions can act as low-energy traps for QPs, providing
a mechanism for studying the dynamics and properties of both the QPs and the
junction. We study the trapping and clearing of QPs from the Andreev bound
states of epitaxial Al-InAs Josephson junctions incorporated in a
superconducting quantum interference device (SQUID) galvanically shorting a
superconducting resonator to ground. We use a neighboring voltage-biased
Josephson junction to inject QPs into the circuit. Upon the injection of QPs,
we show that we can trap and clear QPs when the SQUID is flux-biased. We
examine effects of the microwave loss associated with bulk QP transport in the
resonator, QP-related dissipation in the junction, and QP poisoning events. By
monitoring the QP trapping and clearing in time, we study the dynamics of these
processes and find a time-scale of few microseconds that is consistent with
electron-phonon relaxation in our system and correlated QP trapping and
clearing mechanisms. Our results highlight the QP trapping and clearing
dynamics as well as the associated time-scales in high transparency Josephson
junctions based fabricated on Al-InAs heterostructures
Statewide Molecular Epidemiology of Mycobacterium tuberculosis Transmission in a Moderate- to Low-Incidence State: Are Contact Investigations Enough?
To assess the circumstances of recent transmission of tuberculosis (TB) (progression to active disease <2 years after infection), we obtained DNA fingerprints for 1,172 (99%) of 1,179 Mycobacterium tuberculosis isolates collected from Maryland TB patients from 1996 to 2000. We also reviewed medical records and interviewed patients with genetically matching M. tuberculosis strains to identify epidemiologic links (cluster investigation). Traditional settings for transmission were defined as households or close relatives and friends; all other settings were considered nontraditional. Of 436 clustered patients, 114 had recently acquired TB. Cluster investigations were significantly more likely than contact investigations to identify patients who recently acquired TB in nontraditional settings (33/42 vs. 23/72, respectively; p<0.001). Transmission from a foreign-born person to a U.S.-born person was rare and occurred mainly in public settings. The time from symptom onset to diagnosis was twice as long for transmitters as for nontransmitters (16.8 vs. 8.5 weeks, respectively; p<0.01). Molecular epidemiologic studies showed that eliminating diagnostic delays can prevent TB transmission in nontraditional settings, which elude contact investigations
Measurement of inclusive D*+- and associated dijet cross sections in photoproduction at HERA
Inclusive photoproduction of D*+- mesons has been measured for photon-proton
centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality
Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of
37 pb^-1. Total and differential cross sections as functions of the D*
transverse momentum and pseudorapidity are presented in restricted kinematical
regions and the data are compared with next-to-leading order (NLO) perturbative
QCD calculations using the "massive charm" and "massless charm" schemes. The
measured cross sections are generally above the NLO calculations, in particular
in the forward (proton) direction. The large data sample also allows the study
of dijet production associated with charm. A significant resolved as well as a
direct photon component contribute to the cross section. Leading order QCD
Monte Carlo calculations indicate that the resolved contribution arises from a
significant charm component in the photon. A massive charm NLO parton level
calculation yields lower cross sections compared to the measured results in a
kinematic region where the resolved photon contribution is significant.Comment: 32 pages including 6 figure
Measurement of Jet Shapes in Photoproduction at HERA
The shape of jets produced in quasi-real photon-proton collisions at
centre-of-mass energies in the range GeV has been measured using the
hadronic energy flow. The measurement was done with the ZEUS detector at HERA.
Jets are identified using a cone algorithm in the plane with a
cone radius of one unit. Measured jet shapes both in inclusive jet and dijet
production with transverse energies GeV are presented. The jet
shape broadens as the jet pseudorapidity () increases and narrows
as increases. In dijet photoproduction, the jet shapes have been
measured separately for samples dominated by resolved and by direct processes.
Leading-logarithm parton-shower Monte Carlo calculations of resolved and direct
processes describe well the measured jet shapes except for the inclusive
production of jets with high and low . The observed
broadening of the jet shape as increases is consistent with the
predicted increase in the fraction of final state gluon jets.Comment: 29 pages including 9 figure
An Expert Consensus Statement on the Management of Large Chondral and Osteochondral Defects in the Patellofemoral Joint
© The Author(s) 2020. Background: Cartilage lesions of the patellofemoral joint constitute a frequent abnormality. Patellofemoral conditions are challenging to treat because of complex biomechanics and morphology. Purpose: To develop a consensus statement on the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint using a modified Delphi technique. Study Design: Consensus statement. Methods: A working group of 4 persons generated a list of statements related to the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint to form the basis of an initial survey for rating by a group of experts. The Metrics of Osteochondral Allografts (MOCA) expert group (composed of 28 high-volume cartilage experts) was surveyed on 3 occasions to establish a consensus on the statements. In addition to assessing agreement for each included statement, experts were invited to propose additional statements for inclusion or to suggest modifications of existing statements with each round. Predefined criteria were used to refine statement lists after each survey round. Statements reaching a consensus in round 3 were included within the final consensus document. Results: A total of 28 experts (100% response rate) completed 3 rounds of surveys. After 3 rounds, 36 statements achieved a consensus, with over 75% agreement and less than 20% disagreement. A consensus was reached in 100.00% of the statements relating to functional anatomy of the patellofemoral joint, 88.24% relating to surgical indications, 100.00% relating to surgical technical aspects, and 100.00% relating to rehabilitation, with an overall consensus of 95.5%. Conclusion: This study established a strong expert consensus document relating to the functional anatomy, surgical indications, donor graft considerations for osteochondral allografts, surgical technical aspects, and rehabilitation concepts for the management of large chondral and osteochondral defects in the patellofemoral joint. Further research is required to clinically validate the established consensus statements and better understand the precise indications for surgery as well as which techniques and graft processing/preparation methods should be used based on patient- and lesion-specific factors
Ontogeny of Toll-Like and NOD-Like Receptor-Mediated Innate Immune Responses in Papua New Guinean Infants
Studies addressing the ontogeny of the innate immune system in early life have reported mainly on Toll-like receptor (TLR) responses in infants living in high-income countries, with little or even no information on other pattern recognition receptors or on early life innate immune responses in children living under very different environmental conditions in less-developed parts of the world. In this study, we describe whole blood innate immune responses to both Toll-like and nucleotide-binding oligomerization domain (NOD)-like receptor agonists including the widely used vaccine adjuvant ‘alum’ in a group of Papua New Guinean infants aged 1–3 (n = 18), 4–6 (n = 18), 7–12 (n = 21) and 13–18 (n = 10) months old. Depending on the ligands and cytokines studied, different age-related patterns were found: alum-induced IL-1β and CXCL8 responses were found to significantly decline with increasing age; inflammatory (IL-6, IL-1β, IFN-γ) responses to TLR2 and TLR3 agonists increased; and IL-10 responses remained constant or increased during infancy, while TNF-α responses either declined or remained the same. We report for the first time that whole blood innate immune responses to the vaccine adjuvant alum decrease with age in infancy; a finding that may imply that the adjuvant effect of alum in pediatric vaccines could be age-related. Our findings further suggest that patterns of innate immune development may vary between geographically diverse populations, which in line with the ‘hygiene hypothesis’ particularly involves persistence of innate IL-10 responses in populations experiencing higher infectious pressure
The Star Formation and Nuclear Accretion Histories of Normal Galaxies in the AGES Survey
We combine IR, optical and X-ray data from the overlapping, 9.3 square degree
NOAO Deep Wide-Field Survey (NDWFS), AGN and Galaxy Evolution Survey (AGES),
and XBootes Survey to measure the X-ray evolution of 6146 normal galaxies as a
function of absolute optical luminosity, redshift, and spectral type over the
largely unexplored redshift range 0.1 < z < 0.5. Because only the closest or
brightest of the galaxies are individually detected in X-rays, we use a
stacking analysis to determine the mean properties of the sample. Our results
suggest that X-ray emission from spectroscopically late-type galaxies is
dominated by star formation, while that from early-type galaxies is dominated
by a combination of hot gas and AGN emission. We find that the mean star
formation and supermassive black hole accretion rate densities evolve like
(1+z)^3, in agreement with the trends found for samples of bright, individually
detectable starburst galaxies and AGN. Our work also corroborates the results
of many previous stacking analyses of faint source populations, with improved
statistics.Comment: 19 pages, 15 figures, 3 tables, accepted for publication in Ap
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