839 research outputs found
Effet du couvert forestier sur la précision d'un systÚme de positionnement global différentiel
Effect of forest canopy on the accuracy of a differential global positioning system (dGPS). The possibilities to use dGPS (differential global positioning system) for forest mapping are analyzed. The efficiency of dGPS in forest condition is linked to canopy interference, which intercepts signals sent by some of the satellites or reflect them (multipathing). Two types of equipment have been tested: a Trimble Svee Six coupled with a RDS differential receiver and a Trimble SK8 coupled with an OMNISTAR differential receiver. Recordings have been achieved according to two modes: static (recording on one spot during one minute) and cinematic (moving continuously along the stand limits). Two types of forest canopy were compared: light canopy made of young poplar plantation with few obstacles in the vicinity, and closed canopy of mature spruce stand edged with other mature stand. Cinematic mode efficiency is higher than static one (mean errors are respectively 3.1 m and 9.1 m). In the same way positioning is more accurate for the stand with light canopy than for the other one (mean errors are respectively 2.9 m and 9.4 m). Difference between recording modes are probably due to multipathing effect that filtering algorithm integrated in the GPS receivers are not able to remove in static mode. The efficiency of differential signal reception is also different for the two stands: 1.3/ and 20.5/ of missing differential signal respectively in the light and dense canopy conditions
Solution of the Skyrme HF+BCS equation on a 3D mesh. II. A new version of the Ev8 code
We describe a new version of the EV8 code that solves the nuclear
Skyrme-Hartree-Fock+BCS problem using a 3-dimensional cartesian mesh. Several
new features have been implemented with respect to the earlier version
published in 2005. In particular, the numerical accuracy has been improved for
a given mesh size by (i) implementing a new solver to determine the Coulomb
potential for protons (ii) implementing a more precise method to calculate the
derivatives on a mesh that had already been implemented earlier in our
beyond-mean-field codes. The code has been made very flexible to enable the use
of a large variety of Skyrme energy density functionals that have been
introduced in the last years. Finally, the treatment of the constraints that
can be introduced in the mean-field equations has been improved. The code Ev8
is today the tool of choice to study the variation of the energy of a nucleus
from its ground state to very elongated or triaxial deformations with a
well-controlled accuracy.Comment: 24 pages, 3 figure
Criticality in the configuration-mixed interacting boson model : (1) mixing
The case of U(5)-- mixing in the
configuration-mixed Interacting Boson Model is studied in its mean-field
approximation. Phase diagrams with analytical and numerical solutions are
constructed and discussed. Indications for first-order and second-order shape
phase transitions can be obtained from binding energies and from critical
exponents, respectively
The tensor part of the Skyrme energy density functional. III. Time-odd terms at high spin
This article extends previous studies on the effect of tensor terms in the
Skyrme energy density functional by breaking of time-reversal invariance. We
have systematically probed the impact of tensor terms on properties of
superdeformed rotational bands calculated within the cranked
Hartree-Fock-Bogoliubov approach for different parameterizations covering a
wide range of values for the isoscalar and isovector tensor coupling constants.
We analyze in detail the contribution of the tensor terms to the energies and
dynamical moments of inertia and study their impact on quasi-particle spectra.
Special attention is devoted to the time-odd tensor terms, the effect of
variations of their coupling constants and finite-size instabilities.Comment: 28 pages, 34 figure
Quadrupole collective variables in the natural Cartan-Weyl basis
The matrix elements of the quadrupole collective variables, emerging from
collective nuclear models, are calculated in the natural Cartan-Weyl basis of
O(5) which is a subgroup of a covering structure. Making
use of an intermediate set method, explicit expressions of the matrix elements
are obtained in a pure algebraic way, fixing the -rotational structure
of collective quadrupole models.Comment: submitted to Journal of Physics
The effect of intermittent hypoxic training on performance
This study aimed to verify whether the âlive low, train highâ approach is beneficial for endurance and/or anaerobic cycling performance. Sixteen well-trained athletes completed 90 min of endurance training (60-70% of heart rate reserve) followed by two 30-s all-out sprints (Wingate test), daily for 10 consecutive days. Nine subjects (IHT group) trained with an FâOâ set to produce arterial oxygen saturations of ~88% to ~82%, while 7 subjects (placebo group) trained while breathing a normal gas mixture (FâOâ = 0.21). Four performance tests were conducted at sea-level including a familiarisation and baseline trial, followed by repeat trials at 2 and 9 days post-intervention. Relative to the placebo group mean power during the 30-s Wingate test increased by 3.0% (95% Confidence Limits, CL ± 3.5%) 2 days, and 1.7% (± 3.8%) 9 days post-IHT. Changes in other performance variables (30-s peak power, 20-km mean power, 20-km oxygen cost) were unclear. During the time trial the IHT participantsâ blood lactate concentration, RER and SpOâ relative to the placebo group, was substantially increased at 2 days post-intervention. The addition of IHT into the normal training programme of well-trained athletes produced worthwhile gains in 30-s sprint performance possibly through enhanced glycolysis.Lincoln University Research Fund, Sport and Recreation New Zealan
Prognostic value of bcl-2 expression in invasive breast cancer.
Expression of the bcl-2 proto-oncogene was studied immunohistochemically in 251 invasive ductal breast carcinomas (median follow-up time 91 months, range 24-186 months) and the results were correlated with clinicopathological data and prognostic variables. Sixty-three (25%) tumours were scored bcl-2 negative and 188 (75%) tumours were bcl-2 positive. No relationship could be observed between bcl-2 status and tumour grade, pTNM staging or menopausal status. A strong positive relationship was demonstrated between bcl-2 immunoreactivity and oestrogen receptor status (P < 0.001) and progesterone receptor status (P < 0.001). No prognostic value was demonstrated for bcl-2 expression on disease-free survival and overall survival in axillary node-negative breast cancer patients. However, in axillary node-positive breast cancer patients multivariate analysis demonstrated absence of bcl-2 expression to be independently related to shortened disease-free survival (P = 0.003) and shortened overall survival (P < 0.001). Our results suggest a potential important role for bcl-2 expression as a modulator of response to adjuvant therapy in breast cancer
Electrical Characterization of Submicrometer Silicon Devices by Cross-Sectional Contact Mode Atomic Force Microscopy
Two contact mode atomic force microscopic (AFM) techniques under ambient conditions are presented for the electrical evaluation of cross sectioned silicon devices. In the first technique, a conductive AFM tip is used as a voltage probe to determine the local potential distribution on the cross section of a silicon device under operation. The electrical potential is measured simultaneously with the surface topography with nanometer resolution and mV accuracy, offering an easy way of correlating topographic and electrical features. A second method, nanometer spreading resistance profiling (nano-SRP), performs localized spreading resistance measurements to determine the spatial distribution of charge carriers in silicon structures. The conversion of the resistance profiles into charge carrier profiles as well as the applied correction factors are discussed in more detail. Both methods are used to map electrical characteristics of state-of-the-art silicon structures
Adaptive divergence under gene flow along an environmental gradient in two coexisting stickleback species
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