9,770 research outputs found
Single-file diffusion and kinetics of template assisted assembly of colloids
We report computer simulation studies of the kinetics of ordering of a two
dimensional system of particles on a template with a one dimensional periodic
pattern. In equilibrium one obtains a re-entrant liquid-solid-liquid phase
transition as the strength of the substrate potential is varied. We show that
domains of crystalline order grow as , with with a
possible cross-over to at late times. We argue that the
law originates from {\em single-file} motion and annihilation of defect pairs
of opposite topological charge along channels created by the template.Comment: 4 pages pdflatex 4 pdf figure
A model for reversible electroporation to deliver drugs into diseased tissues
Drug delivery through electroporation could be highly beneficial for the
treatment of different types of diseased tissues within the human body. In this
work, a mathematical model of reversible tissue electroporation is presented
for injecting drug into the diseased cells. The model emphasizes the tissue
boundary where the drug is injected as a point source. Drug loss from the
tissue boundaries through extracellular space is studied. Multiple pulses are
applied to deliver a sufficient amount of drug into the targeted cells. The set
of differential equations that model the physical circumstances are solved
numerically. This model obtains a mass transfer coefficient in terms of pore
fraction coefficient and drug permeability. It controls the drug transport from
extracellular to intracellular space. The drug penetration throughout the
tissue is captured for the application of different pulses. The boundary
effects on drug concentration are highlighted in this study. The advocated
model is able to perform homogeneous drug transport into the cells so that the
affected tissue is treated completely. This model can be applied to optimize
clinical experiments by avoiding the lengthy and costly in vivo and in vitro
experiments.Comment: 18 page
Quantifying pigment cover to assess variation in animal colouration
The study of animal colouration addresses fundamental and applied aspects relevant to a wide range
of fields, including behavioural ecology, environmental adaptation and visual ecology. Although a
variety of methods are available to measure animal colours, only few focus on chromatophores
(specialized cells containing pigments) and pigment migration. Here, we illustrate a freely available
and user friendly method to quantify pigment cover (PiC) with high precision and low effort using
digital images, where the foreground (i.e., pigments in chromatophores) can be detected and
separated from the background. Images of the brown shrimp, Crangon crangon were used to
compare PiC with the traditional Chromatophore Index (CI). Results indicate that PiC outcompetes CI
for pigment detection and transparency measures in terms of speed, accuracy and precision. The
proposed methodology provides researchers with a useful tool to answer essential physiological,
behavioural and evolutionary questions on animal colouration in a wide range of species
On Upward Drawings of Trees on a Given Grid
Computing a minimum-area planar straight-line drawing of a graph is known to
be NP-hard for planar graphs, even when restricted to outerplanar graphs.
However, the complexity question is open for trees. Only a few hardness results
are known for straight-line drawings of trees under various restrictions such
as edge length or slope constraints. On the other hand, there exist
polynomial-time algorithms for computing minimum-width (resp., minimum-height)
upward drawings of trees, where the height (resp., width) is unbounded.
In this paper we take a major step in understanding the complexity of the
area minimization problem for strictly-upward drawings of trees, which is one
of the most common styles for drawing rooted trees. We prove that given a
rooted tree and a grid, it is NP-hard to decide whether
admits a strictly-upward (unordered) drawing in the given grid.Comment: Appears in the Proceedings of the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Lead electrorefining process from exhausted lead acid batteries by using acidic and alkaline electrolytes
The recycling of lead acid batteries (LABs) comprises relevant concerns on the suitable methodologies to recover lead. In this investigation, two electrorefining processes, by using acidic and alkaline electrolytes, have been compared to determine the most significant results of both methodologies. Acidic electrolytes used 200 g/L HBF4, 1.2 g/L H3PO4, 10 g/L H3BO3, and 100 g/L PbO, while the alkaline ones employed 120 g/L NaOH, 75 g/L PbO, 50-92 g/L glycerol, and 2 g/L gelatin. All the solutions were studied by varying temperature and current density (CD) to determine remarkable changes on current efficiency (CE), cell voltage (CV), specific energy consumption (SEC), and on the deposit quality. The results highlighted that by using the acidic electrolyte containing dextrin it is possible to obtain a compact deposit even using high CDs. Acidic solution without dextrin addition allows to obtain good quality deposits by working at 40 degrees C and 100 A/m(2) CD. After testing the behavior of different alkaline electrolytes, it is possible to observe that the solution containing the highest glycerol concentration allows to obtain, for intermediate valued of CD, CE higher than 97% with a SEC of about 0.37 kWh/kg. By comparing the results it is evident that the acidic electrolyte is the one that allows to reach higher productivity with lower SEC. In the selected conditions, lead deposits appear pure and compact.[GRAPHICS]
Multi camera soccer player tracking
Now a day’s spread of super computers, existing of high resolution and low-priced video cameras, and increasing the computerized video analysis has made more curiosity in tracking algorithms. Automatic identification and tracing of multiple moving objects through video scene is an interesting field of computer visualization. Identification and tracking of multiple people is a vital and challenging task for many applications like human-computer interface, video communication, security application and surveillance system. Various researchers offer various algorithms but none of this was work properly to distinguish the players automatically when creating occlusion. The first step to tracking multiple objects in video sequence is detection. Background subtraction is a very popular and effective method for foreground detection (assuming that background should be stationary). In this thesis we apply various background subtraction methods to tackle the difficulties like changing illumination condition, background clutter and camouflage. The method we propose to overcome this problem is operates the background subtraction by calculating the Mahalanobis distances. The second step to track multiple moving objects in soccer scene by using particle filters method that estimate the non-Gaussian, non-linear state-space model, which is a multi-target tracking method. These methods are applied on real soccer video sequences and the result show that it is successfully track and distinguish the players. After tracking is done by using multi camera views, we collecting the data from all cameras and creating geometrical relationship between cameras called Homography
Intense physical activity is associated with cognitive performance in the elderly
Numerous studies have reported positive impacts of physical activity on cognitive function. However, the majority of these studies have utilised physical activity questionnaires or surveys, thus results may have been influenced by reporting biases. Through the objective measurement of routine levels of physical activity via actigraphy, we report a significant association between intensity, but not volume, of physical activity and cognitive functioning. A cohort of 217 participants (aged 60–89 years) wore an actigraphy unit for 7 consecutive days and underwent comprehensive neuropsychological assessment. The cohort was stratified into tertiles based on physical activity intensity. Compared with individuals in the lowest tertile of physical activity intensity, those in the highest tertile scored 9%, 9%, 6% and 21% higher on the digit span, digit symbol, Rey Complex Figure Test (RCFT) copy and Rey Figure Test 30-min recall test, respectively. Statistically, participants in the highest tertile of physical activity intensity performed significantly better on the following cognitive tasks: digit symbol, RCFT copy and verbal fluency test (all P<0.05). The results indicate that intensity rather than quantity of physical activity may be more important in the association between physical activity and cognitive function
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