5,682 research outputs found
Orientation in the diagnosis of intraocular neoplasia, through intraocular fine needle aspiration (IFNA)
IFNA is a safe diagnostic technique that allows diagnostic of neoplastic and inflammatory processes of the eye1. In cats melanoma is common in the eye, skin and oral cavity2. In the eyep, local infiltration to systemic metastases may occur2. Being, the IFNA a method that assists in the diagnosis and therapeutics1,3,4,5. An european female cat, seven years old, was presented to consultation with brown patches of progressive growth in the right iris for four months. The pupillary light reflex, dazzle and menace response were present, and the ocular echography showed an area with iris thickening and with hyperechogenicity1. Due to clinical suspicion of iris melanoma, it was requested radiographic examination of the thorax, abdominal ultrasonography, hematological and biochemical blood analysis1,2, revealing no alterations. The IFNA was performed under general anesthesia introducing the a 26 gauge needle near the limbus and directed to the iris lesion with the bevel facing the surface of the mass3,4. The technique was performed without complications. The cytology using hematoxylin and eosin staining revealed moderate cellularity composed of rounded cells with moderate nuclear pleomorphism, bulky, pale cytoplasm1. The atypical round cells were suggestive of round cell amelanotic melanoma. Due to the cytological orientation, the enucleation of right eye was advised to the owner, which was declined.The diagnosis of ocular melanoma can be directed on clinical grounds and confirmed by anatomopathological exams2. IFNA is a practical, method in aiding the differentiation of neoplastic from non-neoplastic processes. It also helps guiding the surgical procedure and establishing prognosis1,3,4,5
LAMELAR CORNEAL TRANSPLANTATION IN A DOG FOR SURGICAL TREATMENT OF CORNEA DEEP ULCER WITH DESCEMETOCELE.
Corneal transplantation is a procedure indicated for surgical treatment of several corneal diseases, requiring replacement of the affected tissues1,2,3,4. A dog of undefined breed, 5 years old, revealed on ocular examination, a deep corneal ulcer and a Descemet\'s membrane (DM) exposure. Aiming at corneal repair, the surgical technique of lamellar corneal transplantation was used. The perimeter of the transplant was defined with the help of a biopsy punch. With a 1 ml syringe and a 26 G” needle, air was injected into the deep corneal stroma in order to separate DM from stroma1,2. Subsequently paracentesis was performed to reduce ocular pressure and a small air bubble was added in order to help the corneal depthness perspective. With a crescent knife, excision of the compromised tissue was performed1,3. The DM was covered using cryopreserved canine cornea4 at -20°C in 3mg/ml tobramycin solution and thawed at room temperature it was also molded obtaining the appropriate sized tissue for the recoil1. The corneal suture was made using simple isolated points with 8-0 polyglactin and for corneal protection a third eyelid flap was performed1,3. Topical moxifloxacin, tropicamide, EDTA and autologous serum were used in post-surgical treatment3. The third eyelid flap was removed at 15 days post-surgery and a complete corneal repair was observed with total incorporation in the recipient cornea. Lamellar corneal transplantation employing cryopreserved cornea in tobramycin solution has been shown to be effective in the surgical treatment of descemetocele when related to other techniques1,3,4
An unified cosmological evolution driven by a mass dimension one fermionic field
An unified cosmological model for an Universe filled with a mass dimension
one (MDO) fermionic field plus the standard matter fields is considered. After
a primordial quantum fluctuation the field slowly rolls down to the bottom of a
symmetry breaking potential, driving the Universe to an inflationary regime
that increases the scale factor for about 71 e-folds. After the end of
inflation, the field starts to oscillate and can transfer its energy to the
standard model particles through a reheating mechanism. Such a process is
briefly discussed in terms of the admissible couplings of the MDO field with
the electromagnetic and Higgs fields. We show that even if the field loses all
its kinetic energy during reheating, it can evolve as dark matter due a
gravitational coupling (of spinorial origin) with baryonic matter. Since the
field acquires a constant value at the bottom of the potential, a non-null,
although tiny, mass term acts as a dark energy component nowadays. Therefore,
we conclude that MDO fermionic field is a good candidate to drive the whole
evolution of the Universe, in such a way that the inflationary field, dark
matter and dark energy are described by different manifestations of a single
field.Comment: 22 pages, 5 figure
Graphene-based spin-pumping transistor
We demonstrate with a fully quantum-mechanical approach that graphene can
function as gate-controllable transistors for pumped spin currents, i.e., a
stream of angular momentum induced by the precession of adjacent
magnetizations, which exists in the absence of net charge currents.
Furthermore, we propose as a proof of concept how these spin currents can be
modulated by an electrostatic gate. Because our proposal involves nano-sized
systems that function with very high speeds and in the absence of any applied
bias, it is potentially useful for the development of transistors capable of
combining large processing speeds, enhanced integration and extremely low power
consumption
Graphene as a non-magnetic spin-current lens
In spintronics, the ability to transport magnetic information often depends
on the existence of a spin current traveling between two different magnetic
objects acting as source and probe. A large fraction of this information never
reaches the probe and is lost because the spin current tends to travel
omni-directionally. We propose that a curved boundary between a gated and a
non-gated region within graphene acts as an ideal lens for spin currents
despite being entirely of non-magnetic nature. We show as a proof of concept
that such lenses can be utilized to redirect the spin current that travels away
from a source onto a focus region where a magnetic probe is located, saving a
considerable fraction of the magnetic information that would be otherwise lost.Comment: 9 pages, 3 figure
Dynamic RKKY interaction between magnetic moments in graphene nanoribbons
Graphene has been identified as a promising material with numerous
applications, particularly in spintronics. In this paper we investigate the
peculiar features of spin excitations of magnetic units deposited on graphene
nanoribbons and how they can couple through a dynamical interaction mediated by
spin currents. We examine in detail the spin lifetimes and identify a pattern
caused by vanishing density of states sites in pristine ribbons with armchair
borders. Impurities located on these sites become practically invisible to the
interaction, but can be made accessible by a gate voltage or doping. We also
demonstrate that the coupling between impurities can be turned on or off using
this characteristic, which may be used to control the transfer of information
in transistor-like devices.Comment: 10 pages, 10 figure
Cosmic String Wakes in Scalar-Tensor Gravities
The formation and evolution of cosmic string wakes in the framework of a
scalar-tensor gravity are investigated in this work. We consider a simple model
in which cold dark matter flows past an ordinary string and we treat this
motion in the Zel'dovich approximation. We make a comaprison between our
results and previous results obtained in the context of General Relativity. We
propose a mechanism in which the contribution of the scalar field to the
evolution of the wakes may lead to a cosmological observation.Comment: Replaced version to be published in the Classical and Quantum Gravit
- …