177 research outputs found
New Strongly Coupled Sector at the Tevatron and the LHC
We examine the possibility that a new strong interaction is accessible to the
Tevatron and the LHC. In an effective theory approach, we consider a scenario
with a new color-octet interaction with strong couplings to the top quark, as
well as the presence of a strongly coupled fourth-generation which could be
responsible for electroweak symmetry breaking. We apply several constraints,
including the ones from flavor physics. We study the phenomenology of the
resulting parameter space at the Tevatron, focusing on the the forward-backward
asymmetry in top pair production, as well as in the production of the
fourth-generation quarks. We show that if the excess in the top production
asymmetry is indeed the result of this new interaction, the Tevatron could see
the first hints of the strongly coupled fourth-generation quarks. Finally, we
show that the LHC with TeV and integrated
luminosity should observe the production of fourth-generation quarks at a level
at least one order of magnitude above the QCD prediction for the production of
these states.Comment: 8 pages, 12 figure
N-Relaxion: Large Field Excursions from a Few Site Relaxion Model
Relaxion models are an interesting new avenue to explain the radiative
stability of the Standard Model scalar sector. They require very large field
excursions, which are difficult to generate in a consistent UV completion and
to reconcile with the compact field space of the relaxion. We propose an N-site
model which naturally generates the large decay constant needed to address
these issues. Our model offers distinct advantages with respect to previous
proposals: the construction involves non-abelian fields, allowing for
controlled high energy behaviour and more model building possibilities, both in
particle physics and inflationary models, and also admits a continuum limit
when the number of sites is large, which may be interpreted as a warped extra
dimension.Comment: 7 pages, 2 figures; v2: version to appear in PR
Is the LHC Observing the Pseudo-scalar State of a Two-Higgs Doublet Model ?
The ATLAS and CMS collaborations have recently shown data suggesting the
presence of a Higgs boson in the vicinity of 125 GeV. We show that a two-Higgs
doublet model spectrum, with the pseudo-scalar state being the lightest, could
be responsible for the diphoton signal events. In this model, the other scalars
are considerably heavier and are not excluded by the current LHC data. If this
assumption is correct, future LHC data should show a strengthening of the
signal, while the signals in the and
channels should diminish and eventually disappear, due
to the absence of diboson tree-level couplings of the CP-odd state. The heavier
CP-even neutral scalars can now decay into channels involving the CP-odd light
scalar which, together with their larger masses, allow them to avoid the
existing bounds on Higgs searches. We suggest additional signals to confirm
this scenario at the LHC, in the decay channels of the heavier scalars into
and . Finally, this inverted two-Higgs doublet spectrum is
characteristic in models where fermion condensation leads to electroweak
symmetry breaking. We show that in these theories it is possible to obtain the
observed diphoton signal at or somewhat above of the prediction for the
standard model Higgs for the typical values of the parameters predicted.Comment: 6 pages, 5 figures, final version in Physical Review
Are the pentaquark sum rules reliable?
We rewiew and scrutinize the existing mass determinations of the pentaquarks
from the exponential Laplace Sum Rules (LSR). We do not find any sum rule
window for extracting optimal and reliable results from the LSR, due to the
unusual slow convergence of the OPE and to the exceptional important role of
the QCD continuum into the spectral function in this channel. Instead, we use
in this channel,for the first time, Finite Energy Sum Rules (FESR), which
exhibit a nice stability in the QCD continuum threshold t_c, at which one can
extract, with a good accuracy, the mass of the lowest resonance. Including the
D=7, 9 condensate contributions in the OPE, we obtain M_Theta=(1513+- 114) MeV,
and the corresponding residue lambda_Theta^2= -(0.14-- 0.49)x 10^{-9} GeV^{12},
which favours the I=0, J=1/2, and negative parity S-wave interpretation of the
Theta (1540). However, our analysis indicates a degeneracy between the unmixed
I=0 and I=1 S-wave states. In the I=0, J=1/2, P-wave channel, we obtain, for
the P-resonance, M_P = (1.99+- 0.19) GeV and lambda_P= -(0.7--7.1)x 10^{-9}
GeV^{14}, which we expect to be discovered experimentally. Our results also
suggest that some intuitive choices of the continuum threshold used in the LSR
literature are inconsistent with the FESR results. Finally, a study of the
Theta-K-N coupling using a vertex sum rule shows that, for the I=0, S-wave
channel, the leading OPE contributions only start to order alpha_s^2 in the
chiral limit m_s=0, indicating that the Theta is very narrow.Comment: Latex file 6 pages, 5 ps.figures. Contribution to the QCD 04
International Conference (Montpellier-5-9th July 2004) and to HEP-MAD 04
International Conference (Antananarivo 27th Sept-2nd Oct. 2004). To appear in
Nucl. Phys. B (Proc. Suppl.) and in SLAC Econf. on-line Proceedings. Comments
and References adde
Conditioning of hiPSC-derived cardiomyocytes using surface topography obtained with high throughput technology
Surface functionalization of polymers aims to introduce novel properties that favor bioactive responses. We have investigated the possibility of surface functionalization of polyethylene terephthalate (PET) sheets by the combination of laser ablation with hot embossing and the application of such techniques in the field of stem cell research. We investigated the response of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to topography in the low micrometer range. HiPSC-CMs are expected to offer new therapeutic tools for myocardial replacement or regeneration after an infarct or other causes of cardiac tissue loss. However, hiPSC-CMs are phenotypically immature compared to myocytes in the adult myocardium, hampering their clinical application. We aimed to develop and test a high-throughput technique for surface structuring that would improve hiPSC-CMs structural maturation. We used laser ablation with a ps-laser source in combination with nanoimprint lithography to fabricate large areas of homogeneous micron- to submicron line-like pattern with a spatial period of 3 µm on the PET surface. We evaluated cell morphology, alignment, sarcomeric myofibrils assembly, and calcium transients to evaluate phenotypic changes associated with culturing hiPSC-CMs on functionalized PET. Surface functionalization through hot embossing was able to generate, at low cost, low micrometer features on the PET surface that influenced the hiPSC-CMs phenotype, suggesting improved structural and functional maturation. This technique may be relevant for high-throughput technologies that require conditioning of hiPSC-CMs and may be useful for the production of these cells for drug screening and disease modeling applications with lower costs.Fil: Cortella, Lucas R. X.. Universidade de Sao Paulo; BrasilFil: Cestari, Idágene A.. Universidade de Sao Paulo; BrasilFil: Lahuerta, Ricardo D.. Universidade de Sao Paulo; BrasilFil: Arana, Matheus C.. Universidade de Sao Paulo; BrasilFil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Rank, Andreas. Technische Universität Dresden; AlemaniaFil: Lasagni, Andrés F.. Technische Universität Dresden; AlemaniaFil: Cestari, Ismar N.. Universidade de Sao Paulo; Brasi
Forest disturbance and growth processes are reflected in the geographical distribution of large canopy gaps across the Brazilian Amazon
Canopy gaps are openings in the forest canopy resulting from branch fall and tree mortality events. The geographical distribution of large canopy gaps may reflect underlying variation in mortality and growth processes. However, a lack of data at the appropriate scale has limited our ability to study this relationship until now. We detected canopy gaps using a unique LiDAR dataset consisting of 650 transects randomly distributed across 2500 km(2) of the Brazilian Amazon. We characterized the size distribution of canopy gaps using a power law and we explore the variation in the exponent, alpha. We evaluated how the alpha varies across the Amazon, in response to disturbance by humans and natural environmental processes that influence tree mortality rates. We observed that South-eastern forests contained a higher proportion of large gaps than North-western, which is consistent with recent work showing greater tree mortality rates in the Southeast than the Northwest. Regions characterized by strong wind gust speeds, frequent lightning and greater water shortage also had a high proportion of large gaps, indicating that geographical variation in alpha is a reflection of underlying disturbance processes. Forests on fertile soils were also found to contain a high proportion of large gaps, in part because trees grow tall on these sites and create large gaps when they fall; thus, canopy gap analysis picked up differences in growth as well as mortality processes. Finally, we found that human-modified forests had a higher proportion of large gaps than intact forests, as we would expect given that these forests have been disturbed. Synthesis. The proportion of large gaps in the forest canopy varied substantially over the Brazilian Amazon. We have shown that the trends can be explained by geographical variation in disturbance and growth. The frequency of extreme weather events is predicted to increase under climate change, and changes could lead to greater forest disturbance, which should be detectable as an increased proportion of large gaps in intact forests.Peer reviewe
Fractional dynamics and recurrence analysis in cancer model
In this work, we analyze the effects of fractional derivatives in the chaotic
dynamics of a cancer model. We begin by studying the dynamics of a standard
model, {\it i.e.}, with integer derivatives. We study the dynamical behavior by
means of the bifurcation diagram, Lyapunov exponents, and recurrence
quantification analysis (RQA), such as the recurrence rate (RR), the
determinism (DET), and the recurrence time entropy (RTE). We find a high
correlation coefficient between the Lyapunov exponents and RTE. Our simulations
suggest that the tumor growth parameter () is associated with a chaotic
regime. Our results suggest a high correlation between the largest Lyapunov
exponents and RTE. After understanding the dynamics of the model in the
standard formulation, we extend our results by considering fractional
operators. We fix the parameters in the chaotic regime and investigate the
effects of the fractional order. We demonstrate how fractional dynamics can be
properly characterized using RQA measures, which offer the advantage of not
requiring knowledge of the fractional Jacobian matrix. We find that the chaotic
motion is suppressed as decreases, and the system becomes periodic for
. We observe limit cycles for and fixed points for . The fixed point is
determined analytically for the considered parameters. Finally, we discover
that these dynamics are separated by an exponential relationship between
and . Also, the transition depends on a supper transient which
obeys the same relationship
Development of technologies to support the diagnosis of infectious diseases and cancer to support the primary health care
54/2017).
Publisher Copyright:
© 2022, The Author(s).Purpose: Primary Health Care (PHC) is the coordinator of health care in Brazil and needs to be strengthened in the diagnostic field to increase health care quality. Aiming to improve the diagnostic tools currently available in PHC, this work describes the process of development and validation of two point-of-care biomedical devices for screening patients with syphilis or different kinds of cancer. Methods: The development of these devices followed nine stages of action based on the requirements established by the Ministry of Health. During development, both systems followed the stages of circuit planning, software simulation to verify the components used, cost assessment for the acquisition of features, simulation in contact matrix, development of the embedded system, and planning of the printed circuit board and storage box. Results: Both devices underwent preliminary functionality tests to assess their quality. The performance tests applied on the device to diagnose syphilis performed 8,733,194 requests, with a flow of 2426 requests/second, reaching the desired parameters of robustness, integrity, durability, and stability. In addition, functioning tests on the cancer-screening device indicated the ability to detect standard fluorescence in a minimal (150 uL) sample volume. Conclusions: Together, the methodology used for developing the devices resulted in promising equipment to improve the diagnosis and meet the requirements for executing technologies for testing and triaging patients in PHC.publishersversionpublishe
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