10,876 research outputs found
CNPq/INPE-LANDSAT system report of activities
The status of the Brazilian LANDSAT facilities and the results achieved are presented. In addition, a LANDSAT product sales/distribution analysis is provided. Data recording and processing capabilities and planned products are addressed
Liquid-state theory of charged colloids
A simple theory of the fluid state of a charged colloidal suspension is
proposed. The full free energy of a polyelectrolyte solution is calculated. It
is found that the counterions condense onto the polyions forming clusters
composed of one polyion and n counterions. The distribution of cluster sizes is
determined explicitly. In agreement with the current experimental and Monte
Carlo results, no liquid-gas phase separation was encountered.Comment: 4 pages, 2 Postscript figures, uses multicol.sty; changed conten
Donnan equilibrium and the osmotic pressure of charged colloidal lattices
We consider a system composed of a monodisperse charge-stabilized colloidal
suspension in the presence of monovalent salt, separated from the pure
electrolyte by a semipermeable membrane, which allows the crossing of solvent,
counterions, and salt particles, but prevents the passage of polyions. The
colloidal suspension, that is in a crystalline phase, is considered using a
spherical Wigner-Seitz cell. After the Donnan equilibrium is achieved, there
will be a difference in pressure between the two sides of the membrane. Using
the functional density theory, we obtained the expression for the osmotic
pressure as a function of the concentration of added salt, the colloidal volume
fraction, and the size and charge of the colloidal particles. The results are
compared with the experimental measurements for ordered polystyrene lattices of
two different particle sizes over a range of ionic strengths and colloidal
volume fractions.Comment: 8 pages, 4 Postscript figures, uses multicol.sty, to be published in
European Physical Journal
Fast and secure key distribution using mesoscopic coherent states of light
This work shows how two parties A and B can securely share sequences of
random bits at optical speeds. A and B possess true-random physical sources and
exchange random bits by using a random sequence received to cipher the
following one to be sent. A starting shared secret key is used and the method
can be described as an unlimited one-time-pad extender. It is demonstrated that
the minimum probability of error in signal determination by the eavesdropper
can be set arbitrarily close to the pure guessing level. Being based on the
-ry encryption protocol this method also allows for optical amplification
without security degradation, offering practical advantages over the BB84
protocol for key distribution.Comment: 11 pages and 4 figures. This version updates the one published in PRA
68, 052307 (2003). Minor changes were made in the text and one section on
Mutual Information was adde
INPE LANDSAT system
There are no author identified significant results in this report
Liquid Polymorphism and Density Anomaly in a Lattice Gas Model
We present a simple model for an associating liquid in which polymorphism and
density anomaly are connected. Our model combines a two dimensional lattice gas
with particles interacting through a soft core potential and orientational
degrees of freedom represented through thermal \char`\"{}ice
variables\char`\"{} . The competition between the directional attractive forces
and the soft core potential leads to a phase diagram in which two liquid phases
and a density anomaly are present. The coexistence line between the low density
liquid and the high density liquid has a positive slope contradicting the
surmise that the presence of a density anomaly implies that the high density
liquid is more entropic than the low density liquid
INJECTABLE HYBRID SYSTEM FOR STRONTIUM LOCAL DELIVERY TO PROMOTE BONE REGENERATION
In bone tissue regeneration strategies, injectable bone substitutes are very attractive since they can
be applied with minimally invasive surgical procedures and can perfectly fill irregular defects created
in cases of trauma, infection or tumor resection. These materials must combine adequate mechanical
properties with the ability to induce new bone formation. Incorporating strontium (Sr) in bone
substitute biomaterials may be a strategy to achieve high Sr concentrations, not in a systemic but in
a local environment, taking advantage of the osteoanabolic and anti-osteoclastic activity of Sr, for
the enhancement of new bone formation. In this context, the aim of the present work was to
evaluate the response of a Sr-hybrid injectable system for bone regeneration, designed by our
group, consisting of hydroxyapatite microspheres doped with Sr and an alginate vehicle crosslinked in
situ with Sr, in an in vivo scenario. Two different animal models were used, rat (Wistar) and sheep
(Merino Branco) critical sized bone defect. Non Sr-doped similar materials (Ca-hybrid) or empty
defects were used as control. Sr-hybrid system led to an increased bone formation in both center
and periphery of a rat critical sized defect compared to a non Sr–doped similar system, where new
bone formation was restricted to the periphery. Moreover newly formed bone was identified as early
as one week after its implantation in a sheep model. After eight weeks, the bone surrounded the
microspheres, both in the periphery and in the center of the defect. Most importantly, the hybrid
system provided a scaffold for cell migration and tissue ingrowth and offered structural support, as
observed in both models. The effective improvement of local bone formation suggests that this might
be a promising approach for bone regeneration, especially in osteoporotic conditions
Use of flight interception traps of Malaise type and attractive traps for social wasps record (Vespidae: Polistinae)
The literature provides different methodologies for sampling social
wasps, including, flight intercept trap type Malaise and Attractive
trap, however, there is no consensus on its use. In this respect, the
aim of this study was to evaluate the best use of Malaise traps and
Attractive trap in biodiversity work of social wasps, and generate a
collection protocol for the use of these traps. The study was conducted
in the Parque Estadual do Rio Doce, located in the east of the state
of Minas Gerais, in the years 2000, 2001, 2002 and 2004 and in the
Botanical Garden of the Federal University of Juiz de Fora, located in
the southeastern state of Minas Gerais, in years 2011, 2012 and 2013.
15 species were collected using Malaise traps, and, 26 species of social
wasps were collected using Attractive traps. Although the negative
aspects of both traps, complementary methodologies surveys varying
social wasps are useful and it is recommended to choose for using in
accordance with the logistical field
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