14,751 research outputs found
Efeito de coberturas vegetais sobre a porosidade, densidade do solo e condutividade hidráulica saturada de um Argissolo Amarelo Distrocoeso cultivado com mamoeiro.
O tráfego de veículos pesados modifica a estrutura do solo, causando o rompimento de suas resistências naturais ? que se encontram interligadas por forças de atração e repulsão alterando o fluxo de água no solo, reduzindo a produtividade e aumentando os níveis de erosão, já que, geralmente, reduz a taxa de infiltração e aumenta o escoamento superficial (Seixas, 2000); isso ocorre porque a velocidade de infiltração e de redistribuição da água no perfil do solo depende do tamanho dos poros O comportamento do solo em decorrência do tráfego de máquinas vem sendo estudado com freqüência no setor agrícola e os resultados têm evidenciado alterações negativas em suas propriedades físicas. Porém, são poucas as pesquisas relacionadas ao cultivo do mamoeiro que, como se sabe, o uso de máquinas para sua produção é intensivo. Assim, o presente trabalho teve o objetivo de levantar informações sobre o efeito do uso de máquinas e de cobertura vegetal em alguns atributos físicos de um Argissolo Amarelo distrocoeso cultivado com mamoeiro.pdf 154
Long-term visual and microperimetry outcomes following autologous retinal pigment epithelium choroid graft for neovascular age-related macular degeneration
To describe the 2- to 4-year visual and microperimetry outcomes of autologous retinal pigment epithelium (RPE)-choroid graft in patients with neovascular age-related macular degeneration (AMD).In this retrospective cohort study, 12 patients with subfoveal neovascular AMD who had undergone autologous RPE-choroid graft between August 2004 and June 2005 were reviewed. Change in visual acuity (VA), contrast sensitivity (CS), fixation stability and retinal sensitivity on microperimetry after 2-3 years and the rates of late postoperative complications were examined.Patients were followed for 26-48 months (mean, 39). Median preoperative VA (logMAR) was 0.87 but declined to 1.43 (1 year), 1.46 (2 years) and 1.38 (3 years), P = 0.001. Median CS (logCS) was 0.75 preoperatively but declined to 0.45 at 2 years. Six patients had serial microperimetry. Fixation stability declined in 1 but improved in 2 patients. All 6 had decline in retinal sensitivity over the graft during follow up. Retinal detachment did not occur after 12 months but 8 developed epiretinal membrane, 12 had cystic retinal change over the graft and 4 developed recurrent choroidal neovascularization. However, 10 grafts retained autofluorescence signal at 18-48 months of follow up.Autologous RPE-choroid graft can maintain VA, stable fixation and retinal sensitivity in some patients for over 3 years. The spatial correlation between graft autofluorescence, outer retinal structures on optical coherence tomography and retinal sensitivity are consistent with photoreceptor cell rescue. However, we caution the use of this technique as there is high complication rate and delayed loss of retinal function
Variedades de soja anual (Glycine max) para produção de massa e efeitos de métodos de fenação sobre consumo.
Avaliação das variedades de soja anual para produção de matéria seca, capacidade de rebrota após o corte e adequação desta cultura para fenação
Effective Semantic Segmentation in Cataract Surgery: What Matters Most?
Our work proposes neural network design choices that set the state-of-the-art on a challenging public benchmark on cataract surgery, CaDIS. Our methodology achieves strong performance across three semantic segmentation tasks with increasingly granular surgical tool class sets by effectively handling class imbalance, an inherent challenge in any surgical video. We consider and evaluate two conceptually simple data oversampling methods as well as different loss functions. We show significant performance gains across network architectures and tasks especially on the rarest tool classes, thereby presenting an approach for achieving high performance when imbalanced granular datasets are considered. Our code and trained models are available at https://github.com/RViMLab/MICCAI2021_Cataract_semantic_segmentation and qualitative results on unseen surgical video can be found at https://youtu.be/twVIPUj1WZM
A Non-Axisymmetric Parallel Manipulator for Head Stabilisation in Vitreoretinal Surgery
A non-axisymmetric parallel manipulator headrest
design was previously proposed to counter patient head motion
during ophthalmic surgery, and a non-motorized prototype was
built. Custom linear actuators were designed, and installed to
the headrest manipulator prototype in preparation for kinematic
performance test. An inverse kinematic-based control algorithm
was implemented, and initial kinematic testing was done. Finally,
the future plans for the research are briefly explaine
The dynamics of financial stability in complex networks
We address the problem of banking system resilience by applying
off-equilibrium statistical physics to a system of particles, representing the
economic agents, modelled according to the theoretical foundation of the
current banking regulation, the so called Merton-Vasicek model. Economic agents
are attracted to each other to exchange `economic energy', forming a network of
trades. When the capital level of one economic agent drops below a minimum, the
economic agent becomes insolvent. The insolvency of one single economic agent
affects the economic energy of all its neighbours which thus become susceptible
to insolvency, being able to trigger a chain of insolvencies (avalanche). We
show that the distribution of avalanche sizes follows a power-law whose
exponent depends on the minimum capital level. Furthermore, we present evidence
that under an increase in the minimum capital level, large crashes will be
avoided only if one assumes that agents will accept a drop in business levels,
while keeping their trading attitudes and policies unchanged. The alternative
assumption, that agents will try to restore their business levels, may lead to
the unexpected consequence that large crises occur with higher probability
Hydrodynamic model intercomparison for the patos lagoon (Brazil)
An intercomparison study is carried out between two
models with different formulations and spatial
discretizations in order to overcome the limitations posed
by the standard calibration and validation procedures and
improve confidence in the hydrodynamic results for the
Patos Lagoon. Numerical simulations were carried out
applying the TELEMAC and MOHID models, based on
the same boundary conditions and identical calibration
coefficients so differences in calculated flow conditions
result from the formulations and parameterizations of
each model. Results from both models are compared with
measurements from three stations inside the lagoon.
Preliminary results indicate that both models compare
well with the measurements and with each other. These
results increase the confidence on hydrodynamic results
for the Patos Lagoon and provide the first step towards
water quality studies for the area
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