699 research outputs found
Assessment of Biosignals for Managing a Virtual Keyboard
In this paper we propose an assessment of biosignals for handling an
application based on virtual keyboard and automatic scanning. The aim of this
work is to measure the effect of using such application, through different interfaces
based on electromyography and electrooculography, on cardiac and electrodermal
activities. Five people without disabilities have been tested. Each
subject wrote twice the same text using an electromyography interface in first
test and electrooculography in the second one. Each test was divided into four
parts: instruction, initial relax, writing and final relax. The results of the tests
show important differences in the electrocardiogram and electrodermal activity
among the parts of tests.Junta de Andalucía p08-TIC-363
The 8Li Calibration Source for the Sudbury Neutrino Obervatory
A calibration source employing 8Li (t_1/2 = 0.838s) has been developed for
use with the Sudbury Neutrino Observatory (SNO). This source creates a spectrum
of beta particles with an energy range similar to that of the SNO 8B solar
neutrino signal. The source is used to test the SNO detector's energy response,
position reconstruction and data reduction algorithms. The 8Li isotope is
created using a deuterium-tritium neutron generator in conjunction with a 11B
target, and is carried to a decay chamber using a gas/aerosol transport system.
The decay chamber detects prompt alpha particles by gas scintillation in
coincidence with the beta particles which exit through a thin stainless steel
wall. A description is given of the production, transport, and tagging
techniques along with a discussion of the performance and application of the
source.Comment: 11 pages plus 9 figures, Sumbitted to Nuclear Instruments and Methods
A semantical approach to equilibria and rationality
Game theoretic equilibria are mathematical expressions of rationality.
Rational agents are used to model not only humans and their software
representatives, but also organisms, populations, species and genes,
interacting with each other and with the environment. Rational behaviors are
achieved not only through conscious reasoning, but also through spontaneous
stabilization at equilibrium points.
Formal theories of rationality are usually guided by informal intuitions,
which are acquired by observing some concrete economic, biological, or network
processes. Treating such processes as instances of computation, we reconstruct
and refine some basic notions of equilibrium and rationality from the some
basic structures of computation.
It is, of course, well known that equilibria arise as fixed points; the point
is that semantics of computation of fixed points seems to be providing novel
methods, algebraic and coalgebraic, for reasoning about them.Comment: 18 pages; Proceedings of CALCO 200
Assessment of pollen rewards by foraging bees
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The removal of pollen by flower-visiting insects is costly to plants, not only in
terms of production, but also via lost reproductive potential. Modern
angiosperms have evolved various reward strategies to limit these costs, yet
many plant species still offer pollen as a sole or major reward for pollinating
insects.
2. The benefits plants gain by offering pollen as a reward for pollinating are
defined by the behaviour of their pollinators, some of which feed on the pollen
at the flower, while others collect pollen to provision offspring.
3. We explore how pollen impacts on the behaviour and foraging decisions of
pollen-collecting bees, drawing comparisons with what is known for nectar
rewards. This question is of particular interest since foraging bees typically do
not ingest pollen during collection, meaning the sensory pathways involved in
evaluating this resource are not immediately obvious.
4. Previous research focussed on whether foraging bees can determine the quality
of pollen sources offered by different plant species, and attempted to infer the
mechanisms underpinning such evaluations, mainly through observations of
collection preferences in the field
5. More recent experimental research has started to focus on if pollen itself can
mediate the detection of, and learning about, pollen sources and associated
floral cues.
6. We review advancements in the understanding of how bees forage for pollen
and respond to variation in pollen quality, and discuss future directions for
studying how this ancestral floral food reward shapes the behaviour of
pollinating insects
Macrophage Ontogeny Underlies Differences in Tumor-Specific Education in Brain Malignancies.
Extensive transcriptional and ontogenetic diversity exists among normal tissue-resident macrophages, with unique transcriptional profiles endowing the cells with tissue-specific functions. However, it is unknown whether the origins of different macrophage populations affect their roles in malignancy. Given potential artifacts associated with irradiation-based lineage tracing, it remains unclear if bone-marrow-derived macrophages (BMDMs) are present in tumors of the brain, a tissue with no homeostatic involvement of BMDMs. Here, we employed multiple models of murine brain malignancy and genetic lineage tracing to demonstrate that BMDMs are abundant in primary and metastatic brain tumors. Our data indicate that distinct transcriptional networks in brain-resident microglia and recruited BMDMs are associated with tumor-mediated education yet are also influenced by chromatin landscapes established before tumor initiation. Furthermore, we demonstrate that microglia specifically repress Itga4 (CD49D), enabling its utility as a discriminatory marker between microglia and BMDMs in primary and metastatic disease in mouse and human
Evaluating survey designs for targeting preventive chemotherapy against Schistosoma haematobium and Schistosoma mansoni across Sub-Saharan Africa: a geostatistical analysis and modelling study
Abstract
Background
Schistosomiasis control programmes primarily use school-based surveys to identify areas for mass drug administration of preventive chemotherapy. However, as the spatial distribution of schistosomiasis can be highly focal, transmission may not be detected by surveys implemented at districts or larger spatial units. Improved mapping strategies are required to accurately and cost effectively target preventive chemotherapy to remaining foci across all possible spatial distributions of schistosomiasis.
Methods
Here, we use geostatistical models to quantify the spatial heterogeneity of Schistosoma haematobium and S. mansoni across Sub-Saharan Africa using the most comprehensive dataset available on school-based surveys. Applying this information to parameterise simulations, we assess the accuracy and cost of targeting alternative implementation unit sizes across the range of plausible schistosomiasis distributions. We evaluate the consequences of decisions based on survey designs implemented at district and subdistrict levels sampling different numbers of schools. Cost data was obtained from field surveys conducted across multiple countries and years, with cost effectiveness evaluated as the cost per correctly identified school.
Results
Models identified marked differences in prevalence and spatial distributions between countries and species; however, results suggest implementing surveys at subdistrict level increase the accuracy of treatment classifications across most scenarios. While intensively at subdistrict level resulted in the highest classification accuracy, this sampling strategy resulted in the highest costs. Alternatively, sampling the same numbers of schools currently recommended at district levels but stratifying by subdistrict increased cost effectiveness.
Conclusions
This provides a new tool to evaluate schistosomiasis survey designs across a range of transmission settings. Results highlight the importance of considering spatial structure when designing sampling strategies, illustrating that a substantial proportion of children may be undertreated even when an implementation unit is correctly classified. Control programmes need to weigh the increased accuracy of more detailed mapping strategies against the survey costs and treatment priorities
A computational analysis of lower bounds for big bucket production planning problems
In this paper, we analyze a variety of approaches to obtain lower bounds for multi-level production planning problems with big bucket capacities, i.e., problems in which multiple items compete for the same resources. We give an extensive survey of both known and new methods, and also establish relationships between some of these methods that, to our knowledge, have not been presented before. As will be highlighted, understanding the substructures of difficult problems provide crucial insights on why these problems are hard to solve, and this is addressed by a thorough analysis in the paper. We conclude with computational results on a variety of widely used test sets, and a discussion of future research
A radium assay technique using hydrous titanium oxide adsorbent for the Sudbury Neutrino Observatory
As photodisintegration of deuterons mimics the disintegration of deuterons by
neutrinos, the accurate measurement of the radioactivity from thorium and
uranium decay chains in the heavy water in the Sudbury Neutrino Observatory
(SNO) is essential for the determination of the total solar neutrino flux. A
radium assay technique of the required sensitivity is described that uses
hydrous titanium oxide adsorbent on a filtration membrane together with a
beta-alpha delayed coincidence counting system. For a 200 tonne assay the
detection limit for 232Th is a concentration of 3 x 10^(-16) g Th/g water and
for 238U of 3 x 10^(-16) g U/g water. Results of assays of both the heavy and
light water carried out during the first two years of data collection of SNO
are presented.Comment: 12 pages, 4 figure
Volatile and glycosidically bound composition of Loureiro and Alvarinho wines
Composition of Loureiro and Alvarinho wines from the Vinhos Verdes region,
respecting free volatile compounds as well as glycosidically bound aroma precursors,
was exhaustively determined by GC-MS after adsorption on XAD-2 resin. On the
whole, were identified and quantified 120 volatile compounds in the free fraction and
77 glycosidically bound compounds, belonging to C6-compounds, alcohols, fatty acids
ethyl esters, esters of organic acids, acetates, monoterpenic alcohols, monoterpenic
oxides and diols, C13-norisoprenoids, volatile phenols, volatile fatty acids and carbonyl
compounds. Globally, the wines of the two cultivars present similar composition on
volatiles. However, respecting varietal compounds, Loureiro wines are richer than
Alvarinho ones with regard to C6-compounds and monoterpenic compounds, occurring
the opposite for volatile phenols. It was also demonstrate that wines of both varieties
may benefit the aroma reserve, present as glycoconjugates, as it is susceptible of
being technologically explored. Linalool, Ho-trienol, α-terpineol, contributing with
fruity and floral notes, and β-damascenone mostly for Alvarinho, confering tropical
fruit notes, are the varietal compounds which may particularly influence the aroma of
these wines. Respecting fermentative compounds, Alvarinho is also particularly rich in
fatty acids ethyl esters related to lipid metabolism and acetates of fusel alcohols,
which can provide it a fruity character; Loureiro contains higher levels of esters of
organic acids and 2-phenylethanol, conferring fruity and floral notes. Sensory analysis
agree with chemical analyses showing a pronounced tree and tropical fruit character
for Alvarinho wines while Loureiro wines present more intense citrus fruit notes.Centre of Biological
Engineering of Universidade do Minho; Estação Vitivinícola Amândio
Galhano (EVAG); Solar de Serrade; EVAG; Comissão de Viticultura da Região dos Vinhos Verdes
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