350 research outputs found
Confirmation of six Be X-ray binaries in the Small Magellanic Cloud
The X-ray binary population of the Small Magellanic Cloud (SMC) contains a large number of massive X-ray binaries, and the recent survey of the SMC by XMM–Newton has resulted in almost 50 more tentative high-mass X-ray binary (HMXB) candidates. Using probability parameters from Haberl and Sturm together with the optical spectra and timing in this work, we confirm six new massive X-ray binaries in the SMC. We also report two very probable binary periods of 36.4 d in XMM 1859 and of 72.2 d in XMM 2300. These Be X-ray binaries are likely part of the general SMC population, which rarely undergoes an X-ray outburst.This paper is based on ESO data from 079.D−0371 and 088.D−0352. The AAT observations have been supported by the OPTICON project (observing proposals 2011A/014 and 2012/A015), which is funded by the European Commission under the Seventh Framework Programme (FP7). VAM acknowledges financial support from the National Research Foundation of South Africa (Grant 93405) and the World Universities Network. RD, AM and IN from the University of Alicante acknowledge support from the Spanish Government Ministerio de Economía y Competitividad under grant AYA2015-68012-C2-2-P (MINECO/FEDER). ESB acknowledges support from a Claude Leon Foundation fellowship and from the Marie Curie Actions of the European Commission (FP7-COFUND). The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to AU
Probing mSUGRA via the Extreme Universe Space Observatory
An analysis is carried out within mSUGRA of the estimated number of events
originating from upward moving ultra-high energy neutralinos that could be
detected by the Extreme Universe Space Observatory (EUSO). The analysis
exploits a recently proposed technique that differentiates ultra-high energy
neutralinos from ultra-high energy neutrinos using their different absorption
lengths in the Earth's crust. It is shown that for a significant part of the
parameter space, where the neutralino is mostly a Bino and with squark mass
TeV, EUSO could see ultra-high energy neutralino events with
essentially no background. In the energy range 10^9 GeV < E < 10^11 GeV, the
unprecedented aperture of EUSO makes the telescope sensitive to neutralino
fluxes as low as 1.1 \times 10^{-6} (E/GeV)^{-1.3} GeV^{-1} cm^{-2} yr^{-1}
sr^{-1}, at the 95% CL. Such a hard spectrum is characteristic of supermassive
particles' -body hadronic decay. The case in which the flux of ultra-high
energy neutralinos is produced via decay of metastable heavy particles with
uniform distribution throughout the universe is analyzed in detail. The
normalization of the ratio of the relics' density to their lifetime has been
fixed so that the baryon flux produced in the supermassive particle decays
contributes to about 1/3 of the events reported by the AGASA Collaboration
below 10^{11} GeV, and hence the associated GeV gamma-ray flux is in complete
agreement with EGRET data. For this particular case, EUSO will collect between
4 and 5 neutralino events (with 0.3 of background) in ~ 3 yr of running. NASA's
planned mission, the Orbiting Wide-angle Light-collectors (OWL), is also
briefly discussed in this context.Comment: Some discussion added, final version to be published in Physical
Review
Manual / Issue 13 / Storage
Manual, a journal about art and its making. Storage. Manual 13 opens with an introduction by Fred Wilson, who confides, “You can look at all the opulence on display in a museum and begin to understand that something nefarious might be behind it. Storage, for me, is where the action is.” Museums usually make choices for viewers, their curators presenting what they think most important within a category. They can be so good at doing this that visitors sometimes don’t realize there’s anything else to see: they don’t realize the nature of the decisions behind an exhibition, and they accept that the elites have made a judgment about which shoe is the shoe to see. Visitors can learn about what’s great, but they don’t necessarily consider the process of discernment. –– Fred Wilson
The RISD Museum’s thirteenth issue of Manual unpacks the idea and reality of storage—objects museums don’t put on view, works made as containers of various sorts, and more metaphorical considerations about how meanings and narratives are stored. This issue serves as a companion to the Raid the Icebox Now series of exhibitions on view at the RISD Museum through November 2020, in which nine contemporary artists and design collectives use the museum and its collections as a site for critical creative production and presentation. Raid the Icebox Now marks the 50th anniversary of Raid the Icebox 1 with Andy Warhol, held in 1970 at the RISD Museum. Softcover, 120 pages. Published Fall/Winter 2019 by the RISD Museum. Manual 13 (Storage) contributors include: Christina Alderman, Issac M. Alderman, A.H. Jerriod Avant, Hannah Carlson, Wai Yee Chiong, John Dunnigan, Maria Morris Hambourg, David Hartt, Elaine Tyler May, Claire McCardell, Denise Murrell, Ingrid Schaffner, Holly Shaffer, Tanya Sheehan, John W. Smith, Mimi Smith, Sassan Tabatabai, Allen Wexler, and Fred Wilson.https://digitalcommons.risd.edu/risdmuseum_journals/1039/thumbnail.jp
First Measurement of Z/gamma* Production in Compton Scattering of Quasi-real Photons
We report the first observation of Z/gamma* production in Compton scattering
of quasi-real photons. This is a subprocess of the reaction e+e- to
e+e-Z/gamma*, where one of the final state electrons is undetected.
Approximately 55 pb-1 of data collected in the year 1997 at an e+e-
centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been
analysed. The Z/gamma* from Compton scattering has been detected in the
hadronic decay channel. Within well defined kinematic bounds, we measure the
product of cross-section and Z/gamma* branching ratio to hadrons to be
(0.9+-0.3+-0.1) pb for events with a hadronic mass larger than 60 GeV,
dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60
GeV, dominated by (e)egamma* production, this product is found to be
(4.1+-1.6+-0.6) pb. Our results agree with the predictions of two Monte Carlo
event generators, grc4f and PYTHIA.Comment: 18 pages, LaTeX, 5 eps figures included, submitted to Physics Letters
Search for Higgs Bosons in e+e- Collisions at 183 GeV
The data collected by the OPAL experiment at sqrts=183 GeV were used to
search for Higgs bosons which are predicted by the Standard Model and various
extensions, such as general models with two Higgs field doublets and the
Minimal Supersymmetric Standard Model (MSSM). The data correspond to an
integrated luminosity of approximately 54pb-1. None of the searches for neutral
and charged Higgs bosons have revealed an excess of events beyond the expected
background. This negative outcome, in combination with similar results from
searches at lower energies, leads to new limits for the Higgs boson masses and
other model parameters. In particular, the 95% confidence level lower limit for
the mass of the Standard Model Higgs boson is 88.3 GeV. Charged Higgs bosons
can be excluded for masses up to 59.5 GeV. In the MSSM, mh > 70.5 GeV and mA >
72.0 GeV are obtained for tan{beta}>1, no and maximal scalar top mixing and
soft SUSY-breaking masses of 1 TeV. The range 0.8 < tanb < 1.9 is excluded for
minimal scalar top mixing and m{top} < 175 GeV. More general scans of the MSSM
parameter space are also considered.Comment: 49 pages. LaTeX, including 33 eps figures, submitted to European
Physical Journal
A Measurement of the Product Branching Ratio f(b->Lambda_b).BR(Lambda_b->Lambda X) in Z0 Decays
The product branching ratio, f(b->Lambda_b).BR(Lambda_b->Lambda X), where
Lambda_b denotes any weakly-decaying b-baryon, has been measured using the OPAL
detector at LEP. Lambda_b are selected by the presence of energetic Lambda
particles in bottom events tagged by the presence of displaced secondary
vertices. A fit to the momenta of the Lambda particles separates signal from B
meson and fragmentation backgrounds. The measured product branching ratio is
f(b->Lambda_b).BR(Lambda_b->Lambda X) = (2.67+-0.38(stat)+0.67-0.60(sys))%
Combined with a previous OPAL measurement, one obtains
f(b->Lambda_b).BR(Lambda_b->Lambda X) = (3.50+-0.32(stat)+-0.35(sys))%.Comment: 16 pages, LaTeX, 3 eps figs included, submitted to the European
Physical Journal
Measurement of the Michel Parameters in Leptonic Tau Decays
The Michel parameters of the leptonic tau decays are measured using the OPAL
detector at LEP. The Michel parameters are extracted from the energy spectra of
the charged decay leptons and from their energy-energy correlations. A new
method involving a global likelihood fit of Monte Carlo generated events with
complete detector simulation and background treatment has been applied to the
data recorded at center-of-mass energies close to sqrt(s) = M(Z) corresponding
to an integrated luminosity of 155 pb-1 during the years 1990 to 1995. If e-mu
universality is assumed and inferring the tau polarization from neutral current
data, the measured Michel parameters are extracted. Limits on non-standard
coupling constants and on the masses of new gauge bosons are obtained. The
results are in agreement with the V-A prediction of the Standard Model.Comment: 32 pages, LaTeX, 9 eps figures included, submitted to the European
Physical Journal
Motor neuroprosthesis implanted with neurointerventional surgery improves capacity for activities of daily living tasks in severe paralysis: first in-human experience
Background: Implantable brain–computer interfaces (BCIs), functioning as motor neuroprostheses, have the potential to restore voluntary motor impulses to control digital devices and improve functional independence in patients with severe paralysis due to brain, spinal cord, peripheral nerve or muscle dysfunction. However, reports to date have had limited clinical translation. Methods Two participants with amyotrophic lateral sclerosis (ALS) underwent implant in a single-arm, open-label, prospective, early feasibility study. Using a minimally invasive neurointervention procedure, a novel endovascular Stentrode BCI was implanted in the superior sagittal sinus adjacent to primary motor cortex. The participants undertook machinelearning-assisted training to use wirelessly transmitted electrocorticography signal associated with attempted movements to control multiple mouse-click actions, including zoom and left-click. Used in combination with an eye-tracker for cursor navigation, participants achieved Windows 10 operating system control to conduct instrumental activities of daily living (IADL) tasks. Results: Unsupervised home use commenced from day 86 onwards for participant 1, and day 71 for participant 2. Participant 1 achieved a typing task average click selection accuracy of 92.63% (100.00%, 87.50%– 100.00%) (trial mean (median, Q1–Q3)) at a rate of 13.81 (13.44, 10.96–16.09) correct characters per minute (CCPM) with predictive text disabled. Participant 2 achieved an average click selection accuracy of 93.18% (100.00%, 88.19%–100.00%) at 20.10 (17.73, 12.27–26.50) CCPM. Completion of IADL tasks including text messaging, online shopping and managing finances independently was demonstrated in both participants. Conclusion: We describe the first-in-human experience of a minimally invasive, fully implanted, wireless, ambulatory motor neuroprosthesis using an endovascular stent-electrode array to transmit electrocorticography signals from the motor cortex for multiple command control of digital devices in two participants with flaccid upper limb paralysis.Thomas J Oxley, Peter E Yoo, Gil S Rind, Stephen M Ronayne, C M Sarah Lee, Christin Bird, Victoria Hampshire, Rahul P Sharma, Andrew Morokoff, Daryl L Williams, Christopher MacIsaac, Mark E Howard, Lou Irving, Ivan Vrljic, Cameron Williams, Sam E John, Frank Weissenborn, Madeleine Dazenko, Anna H Balabanski, David Friedenberg, Anthony N Burkitt, Yan T Wong, Katharine J Drummond, Patricia Desmond, Douglas Weber, Timothy Denison, Leigh R Hochberg, Susan Mathers, Terence J O, Brien, Clive N May, J Mocco, David B Grayden, Bruce C V Campbell, Peter Mitchell, Nicholas L Opi
The New Look pMSSM with Neutralino and Gravitino LSPs
The pMSSM provides a broad perspective on SUSY phenomenology. In this paper
we generate two new, very large, sets of pMSSM models with sparticle masses
extending up to 4 TeV, where the lightest supersymmetric particle (LSP) is
either a neutralino or gravitino. The existence of a gravitino LSP necessitates
a detailed study of its cosmological effects and we find that Big Bang
Nucleosynthesis places strong constraints on this scenario. Both sets are
subjected to a global set of theoretical, observational and experimental
constraints resulting in a sample of \sim 225k viable models for each LSP type.
The characteristics of these two model sets are briefly compared. We confront
the neutralino LSP model set with searches for SUSY at the 7 TeV LHC using both
the missing (MET) and non-missing ET ATLAS analyses. In the MET case, we employ
Monte Carlo estimates of the ratios of the SM backgrounds at 7 and 8 TeV to
rescale the 7 TeV data-driven ATLAS backgrounds to 8 TeV. This allows us to
determine the pMSSM parameter space coverage for this collision energy. We find
that an integrated luminosity of \sim 5-20 fb^{-1} at 8 TeV would yield a
substantial increase in this coverage compared to that at 7 TeV and can probe
roughly half of the model set. If the pMSSM is not discovered during the 8 TeV
run, then our model set will be essentially void of gluinos and lightest first
and second generation squarks that are \lesssim 700-800 GeV, which is much less
than the analogous mSUGRA bound. Finally, we demonstrate that non-MET SUSY
searches continue to play an important role in exploring the pMSSM parameter
space. These two pMSSM model sets can be used as the basis for investigations
for years to come.Comment: 54 pages, 22 figures; typos fixed, references adde
Espectro de gotas de bicos de pulverização hidráulicos de jato plano e de jato cônico vazio
- …