184 research outputs found
Technical note: Rapid image-based field methods improve the quantification of termite mound structures and greenhouse-gas fluxes
Termite mounds (TMs) mediate biogeochemical processes with global relevance,
such as turnover of the important greenhouse gas methane (CH4).
However, the complex internal and external morphology of TMs impede an
accurate quantitative description. Here we present two novel field methods,
photogrammetry (PG) and cross-sectional image analysis, to
quantify TM external and internal mound structure of 29 TMs of three termite
species. Photogrammetry was used to measure epigeal volume (VE),
surface area (AE) and mound basal area (AB) by
reconstructing 3-D models from digital photographs, and compared against a
water-displacement method and the conventional approach of approximating TMs
by simple geometric shapes. To describe TM internal structure, we introduce
TM macro- and micro-porosity (θM and θμ), the
volume fractions of macroscopic chambers, and microscopic pores in the wall
material, respectively. Macro-porosity was estimated using image analysis of
single TM cross sections, and compared against full X-ray computer tomography
(CT) scans of 17 TMs. For these TMs we present complete pore fractions to
assess species-specific differences in internal structure. The PG method
yielded VE nearly identical to a water-displacement method, while
approximation of TMs by simple geometric shapes led to errors of
4–200 %. Likewise, using PG substantially improved the accuracy of
CH4 emission estimates by 10–50 %. Comprehensive CT scanning
revealed that investigated TMs have species-specific ranges of
θM and θμ, but similar total porosity. Image
analysis of single TM cross sections produced good estimates of
θM for species with thick walls and evenly distributed
chambers. The new image-based methods allow rapid and accurate quantitative
characterisation of TMs to answer ecological, physiological and
biogeochemical questions. The PG method should be applied when measuring
greenhouse-gas emissions from TMs to avoid large errors from inadequate shape
approximations
ATLAS RPC Cosmic Ray Teststand at INFN Lecce
We describe the design and functionality of the cosmic ray teststand built at
INFN Lecce for ATLAS RPC quality control assurance.Comment: XXIV Physics in Collisions Conference (PIC04), Boston, USA, June
2004, 3 pages, LaTex, 2 eps figures. MONP0
Meeting Minutes for October 13, 2016
Raw DICOM image files of CT-scanned termite mound Tp
Single-hit resolution measurement with MEG II drift chamber prototypes
Drift chambers operated with helium-based gas mixtures represent a common
solution for tracking charged particles keeping the material budget in the
sensitive volume to a minimum. The drawback of this solution is the worsening
of the spatial resolution due to primary ionisation fluctuations, which is a
limiting factor for high granularity drift chambers like the MEG II tracker. We
report on the measurements performed on three different prototypes of the MEG
II drift chamber aimed at determining the achievable single-hit resolution. The
prototypes were operated with helium/isobutane gas mixtures and exposed to
cosmic rays, electron beams and radioactive sources. Direct measurements of the
single hit resolution performed with an external tracker returned a value of
110 m, consistent with the values obtained with indirect measurements
performed with the other prototypes.Comment: 18 pages, 18 figure
Servicios de contact center basados en offshore outsourcing
La competencia global obliga a las empresas a reducir sus costos, de forma que han optado por desplazar algunas de sus actividades productivas o de prestaci?n de servicios hacia econom?as que les demanden menores costos, es decir, hacia pa?ses emergentes. Ha surgido as? un tipo de producto denominado offshore outsourcing, que consiste en tercerizar los servicios no estrat?gicos de una determinada empresa, como el servicio de atenci?n al cliente por medio de un contact center localizado en el exterior. La presente investigaci?n analiza las condiciones y posibilidades de la exportaci?n de servicios de atenci?n al cliente por medio de un contact center desde el Per? y propone un modelo y un plan de negocios para una empresa que se instale aqu? a fin de exportar estos servicios de manera competitiva, aprovechando las ventajas que presenta el pa?s en relaci?n con esta actividad mundial, con los consecuentes beneficios para la empresa y la econom?a peruana (generaci?n de utilidades y creaci?n de empleos). Sobre todo, el trabajo intenta demostrar cu?n viable es esta actividad. En la primera parte se abordan aspectos conceptuales sobre los contact center y la metodolog?a aplicada, tambi?n se analizan los mercados mundial y peruano de estos servicios; todo ello con la finalidad de determinar las principales caracter?sticas del mercado mundial de exportaci?n, identificar los factores cr?ticos de ?xito, conocer las tendencias del negocio de offshore outsourcing y, especialmente, a las empresas internacionales y nacionales que exportan los servicios de atenci?n al cliente. En la segunda etapa se realiza el benchmarking de las caracter?sticas de los pa?ses y empresas que destacan en la exportaci?n de servicios de contact center y se propone el plan de negocios mencionado
Rehabilitation strategy for post-stroke recovery using an innovative elbow exoskeleton
Intensive and adaptive rehabilitation therapy is beneficial for post-stroke recovery. Three modes of rehabilitation are generally performed at different stages after stroke: external force-based control in the acute stage, assistive force-based rehabilitation in the midway of recovery and resistive force-based rehabilitation in the last stage. To achieve the above requirements, an innovative elbow exoskeleton has been developed to incorporate the three modes of rehabilitation in a single structure. The structure of the exoskeleton has been designed in such a way that the whole working region is divided into three where each region can provide a different mode of rehabilitation. Recovery rate can be varied for individuals since it depends on various parameters. To evaluate the rate of recovery, three joint parameters have been identified: range of angular movement, angular velocity and joint torque. These parameters are incorporated into the framework of planning a novel rehabilitation strategy, which is discussed in this article along with the structural description of the designed exoskeleton
Measurement of the radiative decay of polarized muons in the MEG experiment
We studied the radiative muon decay by
using for the first time an almost fully polarized muon source. We identified a
large sample (~13000) of these decays in a total sample of 1.8x10^14 positive
muon decays collected in the MEG experiment in the years 2009--2010 and
measured the branching ratio B() =
(6.03+-0.14(stat.)+-0.53(sys.))x10^-8 for E_e > 45 MeV and E_{\gamma} > 40 MeV,
consistent with the Standard Model prediction. The precise measurement of this
decay mode provides a basic tool for the timing calibration, a normalization
channel, and a strong quality check of the complete MEG experiment in the
search for process.Comment: 8 pages, 7 figures. Added an introduction to NLO calculation which
was recently calculated. Published versio
The measuring systems of the wire tension for the MEG II Drift Chamber by means of the resonant frequency technique
The ultra-low mass Cylindrical Drift Chamber designed for the MEG experiment
upgrade is a challenging apparatus made of 1728 phi = 20 micron gold plated
tungsten sense wires, 7680 phi = 40 micron and 2496 phi = 50 micron silver
plated aluminum field wires. Because of electrostatic stability requirements
all the wires have to be stretched at mechanical tensions of about 25, 19 and
29 g respectively which must be controlled at a level better than 0.5 g. This
chamber is presently in acquisition, but during its construction about 100
field wires broke, because of chemical corrosion induced by the atmospheric
humidity. On the basis of the experience gained with this chamber we decided to
build a new one, equipped with a different type of wires less sensitive to
corrosion. The choice of the new wire required a deep inspection of its
characteristics and one of the main tools for doing this is a system for
measuring the wire tension by means of the resonant frequency technique, which
is described in this paper. The system forces the wires to oscillate by
applying a sinusoidal signal at a known frequency, and then measures the
variation of the capacitance between a wire and a common ground plane as a
function of the external signal frequency. We present the details of the
measuring system and the results obtained by scanning the mechanical tensions
of two samples of MEG II CDCH wires and discuss the possible improvements of
the experimental apparatus and of the measuring technique.Comment: Ten pages, twelve figures, to be submitted to Nuclear Instruments and
Methods
Gas Distribution and Monitoring for the Drift Chamber of the MEG-II Experiment
The reconstruction of the positron trajectory in the MEG-II experiment
searching for the decay uses a cylindrical drift chamber
operated with a helium-isobutane gas mixture. A stable performance of the
detector in terms of its electron drift properties, avalanche multiplication,
and with a gas mixture of controlled composition and purity has to be provided
and continuously monitored. In this paper we describe the strategies adopted to
meet the requirements imposed by the target sensitivity of MEG-II, including
the construction and commissioning of a small chamber for an online monitoring
of the gas quality.Comment: 12 pages, 6 figures, submitted to Journal of Instrumentatio
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