24,654 research outputs found
Higgs boson searches at LEP
In this paper we report on the legacy of Higgs boson searches at LEP.
Specifically, the results of the statistical combination of the searches
carried out by the ALEPH, DELPHI, L3 and OPAL experiments are presented. In the
search for the Standard Model (SM) Higgs boson, a signal with mh<114.4 GeV/c^2
has been excluded at the 95% confidence level (CL) or higher. The LEP
collaborations also carried out extensive searches for Higgs particles
predicted by many scenarios beyond the Standard Model. Here we can only report
on a very small fraction of these searches and refer the reader to the complete
list of LEP-combined search results.Comment: 3 pages, 2 figures; submitted for proceedings of EPS HEP2007
Conference (19-25 July; Manchester, UK
Big Data as a Technology-to-think-with for Scientific Literacy
This research aimed to identify indications of scientific literacy resulting
from a didactic and investigative interaction with Google Trends Big Data
software by first-year students from a high-school in Novo Hamburgo, Southern
Brazil. Both teaching strategies and research interpretations lie on four
theoretical backgrounds. Firstly, Bunge's epistemology, which provides a
thorough characterization of Science that was central to our study. Secondly,
the conceptual framework of scientific literacy of Fives et al. that makes our
teaching focus precise and concise, as well as supports one of our
methodological tool: the SLA (scientific literacy assessment). Thirdly, the
"crowdledge" construct from dos Santos, which gives meaning to our study when
as it makes the development of scientific literacy itself versatile for paying
attention on sociotechnological and epistemological contemporary phenomena.
Finally, the learning principles from Papert's Constructionism inspired our
educational activities. Our educational actions consisted of students, divided
into two classes, investigating phenomena chose by them. A triangulation
process to integrate quantitative and qualitative methods on the assessments
results was done. The experimental design consisted in post-tests only and the
experimental variable was the way of access to the world. The experimental
group interacted with the world using analyses of temporal and regional plots
of interest of terms or topics searched on Google. The control class did
'placebo' interactions with the world through on-site observations of
bryophytes, fungus or whatever in the schoolyard. As general results of our
research, a constructionist environment based on Big Data analysis showed
itself as a richer strategy to develop scientific literacy, compared to a free
schoolyard exploration.Comment: 23 pages, 2 figures, 8 table
A critical study of the role of the surface oxide layer in titanium bonding
Scanning electron microscope/X-ray photoelectron spectroscopy (SEM/XPS) analysis of fractured adhesively bonded Ti 6-4 samples is discussed. The text adhesives incuded NR 056X polyimide, polypheylquinoxaline (PPQ), and LARC-13 polyimide. Differentiation between cohesive and interfacial failure was based on the absence of presence of a Ti 2p XPS photopeak. In addition, the surface oxide layer on Ti-(6A1-4V) adherends is characterized and bond strength and durability are addressed. Bond durability in various environmental conditions is discussed
A critical study of the role of the surface oxide layer in titanium bonding
The molecular understanding of the role which the surface oxide layer of the adherend plays in titanium bonding is studied. The effects of Ti6-4 adherends pretreatment, bonding conditions, and thermal aging of the lap shear specimens were studied. The use of the SEM/EDAX and ESCA techniques to study surface morphology and surface composition was emphasized. In addition, contact angles and both infrared and visible reflection spectroscopy were used in ancillary studies
Multispecies Fruit Flower Detection Using a Refined Semantic Segmentation Network
In fruit production, critical crop management decisions are guided by bloom intensity, i.e., the number of flowers present in an orchard. Despite its importance, bloom intensity is still typically estimated by means of human visual inspection. Existing automated computer vision systems for flower identification are based on hand-engineered techniques that work only under specific conditions and with limited performance. This letter proposes an automated technique for flower identification that is robust to uncontrolled environments and applicable to different flower species. Our method relies on an end-to-end residual convolutional neural network (CNN) that represents the state-of-the-art in semantic segmentation. To enhance its sensitivity to flowers, we fine-tune this network using a single dataset of apple flower images. Since CNNs tend to produce coarse segmentations, we employ a refinement method to better distinguish between individual flower instances. Without any preprocessing or dataset-specific training, experimental results on images of apple, peach, and pear flowers, acquired under different conditions demonstrate the robustness and broad applicability of our method
False vacuum decay: effective one-loop action for pair creation of domain walls
An effective one-loop action built from the soliton field itself for the
two-dimensional (2D) problem of soliton pair creation is proposed. The action
consists of the usual mass term and a kinetic term in which the simple
derivative of the soliton field is replaced by a covariant derivative. In this
effective action the soliton charge is treated no longer as a topological
charge but as a Noether charge. Using this effective one-loop action, the
soliton-antisoliton pair production rate is calculated and one recovers Stone's
exponential factor and the prefactor of Kiselev, Selivanov and Voloshin. The
results are also valid straightforwardly to the problem of pair creation rate
of domain walls in dimensions greater than 2.Comment: 12 pages, Late
Arbitrary bi-dimensional finite strain crack propagation
In the past two decades numerous numerical procedures for crack propagation have been developed. Lately,
enrichment methods (either local, such as SDA or global, such as XFEM) have been applied with success to simple
problems, typically involving some intersections. For arbitrary finite strain propagation, numerous difficulties are
encountered: modeling of intersection and coalescence, step size dependence and the presence of distorted finite
elements. In order to overcome these difficulties, an approach fully capable of dealing with multiple advancing
cracks and self-contact is presented (see Fig.1). This approach makes use of a coupled Arbitrary Lagrangian-Eulerian
method (ALE) and local tip remeshing. This is substantially less costly than a full remeshing while retaining its full
versatility. Compared to full remeshing, angle measures and crack paths are superior. A consistent continuationbased
linear control is used to force the critical tip to be exactly critical, while moving around the candidate set.
The critical crack front is identified and propagated when one of the following criteria reaches a material limiting
value: (i) the stress intensity factor; or (ii) the element-ahead tip stress. These are the control equations.
The ability to solve crack intersection and coalescence problems is shown. Additionally, the independence from
crack tip and step size and the absence of blade and dagger-shaped finite elements is observed. Classic benchmarks
are computed leading to excellent crack path and load-deflection results, where convergence rate is quadratic
Upper limit on mh in the MSSM and M-SUGRA vs. prospective reach of LEP
The upper limit on the lightest CP-even Higgs boson mass, mh, is analyzed
within the MSSM as a function of tan(beta) for fixed mtop and Msusy. The impact
of recent diagrammatic two-loop results on this limit is investigated. We
compare the MSSM theoretical upper bound on mh with the lower bound obtained
from experimental searches at LEP. We estimate that with the LEP data taken
until the end of 1999, the region mh < 108.2 GeV can be excluded at the 95%
confidence level. This corresponds to an excluded region 0.6 <= tan(beta) <=
1.9 within the MSSM for mtop = 174.3 GeV and Msusy <= 1 TeV. The final
exclusion sensitivity after the end of LEP, in the year 2000, is also briefly
discussed. Finally, we determine the upper limit on mh within the Minimal
Supergravity (M-SUGRA) scenario up to the two-loop level, consistent with
radiative electroweak symmetry breaking. We find an upper bound of mh \approx
127 GeV for mtop = 174.3 GeV in this scenario, which is slightly below the
bound in the unconstrained MSSM.Comment: 10 pages, 3 figure
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