5,112 research outputs found
Multiscale model for the effects of adaptive immunity suppression on the viral therapy of cancer
Oncolytic virotherapy - the use of viruses that specifically kill tumor cells
- is an innovative and highly promising route for treating cancer. However, its
therapeutic outcomes are mainly impaired by the host immune response to the
viral infection. In the present work, we propose a multiscale mathematical
model to study how the immune response interferes with the viral oncolytic
activity. The model assumes that cytotoxic T cells can induce apoptosis in
infected cancer cells and that free viruses can be inactivated by neutralizing
antibodies or cleared at a constant rate by the innate immune response. Our
simulations suggest that reprogramming the immune microenvironment in tumors
could substantially enhance the oncolytic virotherapy in immune-competent
hosts. Viable routes to such reprogramming are either in situ virus-mediated
impairing of CD T cells motility or blockade of B and T lymphocytes
recruitment. Our theoretical results can shed light on the design of viral
vectors or new protocols with neat potential impacts on the clinical practice.Comment: 14 pages, 4 figure
Limits of the energy-momentum tensor in general relativity
A limiting diagram for the Segre classification of the energy-momentum tensor
is obtained and discussed in connection with a Penrose specialization diagram
for the Segre types. A generalization of the coordinate-free approach to limits
of Paiva et al. to include non-vacuum space-times is made. Geroch's work on
limits of space-times is also extended. The same argument also justifies part
of the procedure for classification of a given spacetime using Cartan scalars.Comment: LaTeX, 21 page
Photoassociative ionization of Na inside a storage ring
Motivated by recent interest in low dimensional arrays of atoms, we
experimentally investigated the way cold collisional processes are affected by
the geometry of the considered atomic sample. More specifically, we studied the
case of photoassociative ionization (PAI) both in a storage ring where
collision is more unidirectional in character and in a trap with clear
undefinition of collision axis. First, creating a ring shaped trap (atomotron)
we investigated two-color PAI dependence with intensity and polarization of a
probing laser. The intensity dependence of the PAI rate was also measured in a
magneto-optical trap presenting equivalent temperature and density conditions.
Indeed, the results show that in the ring trap, the value of the PAI rate
constant is much lower and does not show evidences of saturation, unlike in the
case of the 3D-MOT. Cold atomic collisions in storage ring may represent new
possibilities for study.Comment: 5 pages, 5 figures; Accepted by Optics Communicatio
Análise do comportamento in vitro de explantes foliares de pequizeiro (Caryocar brasiliense camb.) através de RAPD.
xEdição de resumos do 7º Congresso Brasileiro de Fisiologia Vegetal, BrasÃlia, 1999
Teegi: Tangible EEG Interface
We introduce Teegi, a Tangible ElectroEncephaloGraphy (EEG) Interface that
enables novice users to get to know more about something as complex as brain
signals, in an easy, en- gaging and informative way. To this end, we have
designed a new system based on a unique combination of spatial aug- mented
reality, tangible interaction and real-time neurotech- nologies. With Teegi, a
user can visualize and analyze his or her own brain activity in real-time, on a
tangible character that can be easily manipulated, and with which it is
possible to interact. An exploration study has shown that interacting with
Teegi seems to be easy, motivating, reliable and infor- mative. Overall, this
suggests that Teegi is a promising and relevant training and mediation tool for
the general public.Comment: to appear in UIST-ACM User Interface Software and Technology
Symposium, Oct 2014, Honolulu, United State
Charge-density waves in one-dimensional Hubbard superlattices
We study the formation of charge density waves (CDW's) in one-dimensional
Hubbard superlattices, modeled by a repeated pattern of repulsive (U>0) and
free (U=0) sites. By means of Lanczos diagonalizations for the ground state, we
calculate the charge structure factor. Our results show that while the
superlattice structure affects the modulation of the charge density waves, the
periodicity can still be predicted through an effective density. We also show
that, for a fixed repulsive layer thickness, the periodicity of the CDW is an
oscillatory function of the free layer thickness.Comment: 4 pages, 4 figure
Quantum tomography via equidistant states
We study the possibility of performing quantum state tomography via
equidistant states. This class of states allows us to propose a non-symmetric
informationally complete POVM based tomographic scheme. The scheme is defined
for odd dimensions and involves an inversion which can be analytically carried
out by Fourier transform
Asymmetric band diagrams in photonic crystals with a spontaneous nonreciprocal response
We study the propagation of electromagnetic waves in layered photonic crystals formed by materials with a spontaneous nonreciprocal response, such as Tellegen (axion) media or topological insulators. Surprisingly, it is proven that stratified Tellegen photonic crystals that break simultaneously the space inversion and time-reversal symmetries have always symmetric dispersion diagrams. Interestingly, we show that by combining chiral and nonreciprocal materials the photonic band diagrams can exhibit a spectral asymmetry such that omega(k) not equal omega(-k). Furthermore, it is demonstrated that in some conditions two juxtaposed Tellegen medium layers have an electromagnetic response analogous to that of a biased ferrite slab.info:eu-repo/semantics/publishedVersio
A layering model for superconductivity in the borocarbides
We propose a superlattice model to describe superconductivity in layered
materials, such as the borocarbide families with the chemical formul\ae\
BC and BC, with being (essentially) a rare earth, and a
transition metal. We assume a single band in which electrons feel a local
attractive interaction (negative Hubbard-) on sites representing the B
layers, while U=0 on sites representing the C layers; the multi-band
structure is taken into account minimally through a band offset . The
one-dimensional model is studied numerically through the calculation of the
charge gap, the Drude weight, and of the pairing correlation function. A
comparison with the available information on the nature of the electronic
ground state (metallic or superconducting) indicates that the model provides a
systematic parametrization of the whole borocarbide family.Comment: 4 figure
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