5,467 research outputs found
Compact radio sources and jet-driven AGN feedback in the early Universe: Constraints from integral-field spectroscopy
To investigate the impact of radio jets during the formation epoch of their
massive host galaxies, we present an analysis of two massive, log(M_stel/
M_sun)~10.6 and 11.3, compact radio galaxies at z=3.5, TNJ0205+2242 and
TNJ0121+1320. Their small radio sizes (R<= 10 kpc) are most likely a sign of
youth. We compare their radio properties and gas dynamics with those in well
extended radio galaxies at high redshift, which show strong evidence for
powerful, jet-driven outflows of significant gas masses (M 10^9-10 M_sun). Our
analysis combines rest-frame optical integral-field spectroscopy with existing
radio imaging, CO emission line spectra, and rest-frame UV spectroscopy.
[OIII]5007 line emission is compact in both galaxies and lies within the region
defined by the radio lobes. For TNJ0205+2242, the Ly-alpha profile narrows
significantly outside the jet radius, indicating the presence of a quiescent
halo. TNJ0121+1320 has two components separated by ~10 kpc and a velocity
offset of ~300 km s^-1. If motions are gravitational, this implies a dynamical
mass of 2x10^11 M_sun for the more massive, radio-loud component. The dynamical
mass, molecular gas mass measured from the CO line emission, and radio
luminosity of these two compact radio galaxies imply that compact radio sources
may well develop large-scale, energetic outflows as observed in extended radio
galaxies, with the potential of removing significant fractions of the ISM from
the host galaxy. The absence of luminous emission line gas extending beyond the
radio emission in these sources agrees with the observed timescales and outflow
rates in extended radio galaxies, and adds further evidence that the energetic,
large-scale outflows observed in extended radio sources (Nesvadba et al. 2006)
are indeed the result of influence of the radio jet.Comment: A&A accepte
Geographically touring the eastern bloc: British geography, travel cultures and the Cold War
This paper considers the role of travel in the generation of geographical knowledge of the eastern bloc by British geographers. Based on oral history and surveys of published work, the paper examines the roles of three kinds of travel experience: individual private travels, tours via state tourist agencies, and tours by academic delegations. Examples are drawn from across the eastern bloc, including the USSR, Poland, Romania, East Germany and Albania. The relationship between travel and publication is addressed, notably within textbooks, and in the Geographical Magazine. The study argues for the extension of accounts of cultures of geographical travel, and seeks to supplement the existing historiography of Cold War geography
First radial velocity results from the MINiature Exoplanet Radial Velocity Array (MINERVA)
The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated
observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec
spectrograph. The MINERVA mission is to discover super-Earths in the habitable
zones of nearby stars. This can be accomplished with MINERVA's unique
combination of high precision and high cadence over long time periods. In this
work, we detail changes to the MINERVA facility that have occurred since our
previous paper. We then describe MINERVA's robotic control software, the
process by which we perform 1D spectral extraction, and our forward modeling
Doppler pipeline. In the process of improving our forward modeling procedure,
we found that our spectrograph's intrinsic instrumental profile is stable for
at least nine months. Because of that, we characterized our instrumental
profile with a time-independent, cubic spline function based on the profile in
the cross dispersion direction, with which we achieved a radial velocity
precision similar to using a conventional "sum-of-Gaussians" instrumental
profile: 1.8 m s over 1.5 months on the RV standard star HD 122064.
Therefore, we conclude that the instrumental profile need not be perfectly
accurate as long as it is stable. In addition, we observed 51 Peg and our
results are consistent with the literature, confirming our spectrograph and
Doppler pipeline are producing accurate and precise radial velocities.Comment: 22 pages, 9 figures, submitted to PASP, Peer-Reviewed and Accepte
Implementation of Fourier transform infrared spectroscopy for the rapid typing of uropathogenic Escherichia coli.
In this paper, we demonstrate that Fourier transform infrared (FT-IR) spectroscopy is able to discriminate rapidly between uropathogenic Escherichia coli (UPEC) of key lineages with only relatively simple sample preparation. A total of 95 bacteria from six different epidemiologically important multilocus sequence types (ST10, ST69, ST95, ST73, ST127 and ST131) were used in this project and principal component-discriminant function analysis (PC-DFA) of these samples produced clear separate clustering of isolates, based on the ST. Analysis of data using partial least squares-discriminant analysis (PLS-DA), incorporating cross-validation, indicated a high prediction accuracy of 91.19% for ST131. These results suggest that FT-IR spectroscopy could be a useful method for the rapid identification of members of important UPEC STs
Development of novel adenoviral vectors to overcome challenges observed with HAdV-5 based constructs
Recombinant vectors based on human adenovirus serotype 5 (HAdV-5) have been extensively studied in pre-clinical models and clinical trials over the last two decades. However, the thorough understanding of the HAdV-5 interaction with human subjects has uncovered major concerns about its product applicability. High vector-associated toxicity and widespread pre-existing immunity have been shown to significantly impede the effectiveness of HAdV-5 mediated gene transfer. It is therefore that the in depth knowledge attained working on HAdV-5 is currently being used to develop alternative vectors. Here, we provide a comprehensive overview of data obtained in recent years disqualifying the HAdV-5 vector for systemic gene delivery as well as novel strategies being pursued to overcome the limitations observed with particular emphasis on the ongoing vectorization efforts to obtain vectors based on alternative serotypes
Reflectivity, Reflexivity, Reflexivism: IR's 'Reflexive Turn' - and Beyond
The notion of âreflexivityâ has been so intimately tied to the critique of positivism and empiricism in International Relations (IR) that the emergence of post-positivism has naturally produced the anticipation of a âreflexive turnâ in IR theory. Three decades after the launch of the post-positivist critique, however, reflexive IR has failed to impose itself as either a clear or serious contender to mainstream scholarship. Reasons for this failure include: the proliferation of different understandings of âreflexivityâ in IR theory that entail significantly different projects and concerns for IR scholarship; the equation of âreflexive theoryâ with âcriticalâ and âemancipatory theoryâ and the consequent confusion of ethical/normative issues with strictly epistemic/theoretical ones; and the refusal to consider reflexive IR as a âresearch programmeâ concerned with empirical knowledge, not just meta-explanation. The development of reflexivity in IR theory as a sustainable cognitive and praxeological effort is nonetheless possible â and still needed. This article suggests what taking the âreflexive turnâ would really entail for IR.</jats:p
Current-induced microwave excitation of a domain wall confined in a magnetic wire with bi-axial anisotropy
We studied the current-induced magnetization dynamics of a domain wall
confined in a magnetic wire with bi-axial anisotropy. We showed that above the
threshold current density, breathing-mode excitation, where the thickness of
the domain wall oscillates, is induced by spin-transfer torque. We found that
the breathing-mode can be applied as a source of microwave oscillation because
the resistance of the domain wall is a function of the domain wall thickness.
In a current sweep simulation, the frequency of the breathing-mode exhibits
hysteresis because of the confinement.Comment: 5 pages 4 figure
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
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