3,694 research outputs found
Detectors and Concepts for sub-100 ps timing with gaseous detectors
We give a short compendium of the main ongoing detectors and concepts capable
of performing accurate sub-100 ps timing at high particle fluxes and on large
areas, through technologies based on gaseous media. We briefly discuss the
state-of-the-art, technological limitations and prospects, and a new bizarre
idea
Marginally Trapped Surfaces in the Nonsymmetric Gravitational Theory
We consider a simple, physical approach to the problem of marginally trapped
surfaces in the Nonsymmetric Gravitational Theory (NGT). We apply this approach
to a particular spherically symmetric, Wyman sector gravitational field,
consisting of a pulse in the antisymmetric field variable. We demonstrate that
marginally trapped surfaces do exist for this choice of initial data.Comment: REVTeX 3.0 with epsf macros and AMS symbols, 3 pages, 1 figur
Expresión de ICAM-1 en el Endotelio de Arterias Humanas Mediante Inmunohistoquímica
Moore-Carrasco, R (reprint author), Univ Talca, Fac Ciencias Salud, Dept Bioquim Clin & Inmunohematol, Programa Invest Factores Riesgo Enfermedades Card, POB 747, Talca, Chile.Cardiovascular diseases (CVD) are the leading cause of death in the world. Among them the ischemic type are of great importance. where the development of atherosclerotic plaques is the central pathophysiological process. The study of atherosclerosis is critical to understand how this disease process begins and factors influencing its development. Various laboratory methods, including immunohistochemistry, allow the recognition of cells and molecules involved in the atheromatous process that are interacting according to the progression of the lesion. A marker of endothelial dysfunction is the increased expression of intercellular adhesion molecule ICAM-1. In this paper, an immunohistochemistry method was standardized for the adhesion molecule ICAM-1, and its expression was studied in healthy human arteries with atheromatous plaque. In samples of human arteries with atherosclerotic disease, the expression of ICAM-1 was observed lobe increased, but was hardly recognizable. This mainly because the tissue used as a control for standardization was a tonsil with an inflammatory process and hyperplasia, which significantly increases the expression of ICAM-1. The implementation of the immunohistochemistry method for ICAM-1 in human arteries will reveal endothelial dysfunction states that will enable a future design and implementation of methods of diagnosis in atherosclerotic processes in the early stages
Clinical guideline SEOM: cancer of unknown primary site
Cancer of unknown primary site is a histologically confirmed cancer which is manifested in advanced stage, with no identifiable primary site after the use of standard diagnostic procedures. Patients are initially placed into one of categories based upon the examination of the initial biopsy: adenocarcinoma, squamous cell carcinoma, neuroendocrine carcinoma and poorly differentiated carcinoma. Appropriate patient management requires an understanding of several clinicopathologic features that help to identify several subsets of patients with more responsive tumors
Using the second-order information for reconfigurability analysis and design in the fault tolerant framework
The control reconfigurability measure defines the capability of a control system to allow recovery of performance when faults occur; therefore, it has been intended to be a tool for designing and synthesizing approaches in the fault tolerant control context. Reconfigurability depends on the controllability gramian, also known as the second-order information (SOI) in a broad sense. This paper proposes the assignation, by feedback, of the deterministic SOI in order to set the control reconfigurability of a given linear system. The theory concerned with this assignation is reviewed, then constructive theorems are given for finding constant feedback gains that approximate a required control reconfigurability for ease implementation. Also an unification of the reconfigurability measures proposed in the fault tolerance literature is given. Once the SOI is assigned by feedback, it can be computed online by using an identification method, which uses process input/output data. Results from simulation of the three tanks hydraulic benchmark, show that this approach can provide information about the system performance for fault tolerant purposes, thus online control reconfigurability computation and fault accommodation are considered. The approach presented in the paper gives an alternative for supervision taking into account the reconfigurability assigned by design
Computer model validation with functional output
A key question in evaluation of computer models is Does the computer model
adequately represent reality? A six-step process for computer model validation
is set out in Bayarri et al. [Technometrics 49 (2007) 138--154] (and briefly
summarized below), based on comparison of computer model runs with field data
of the process being modeled. The methodology is particularly suited to
treating the major issues associated with the validation process: quantifying
multiple sources of error and uncertainty in computer models; combining
multiple sources of information; and being able to adapt to different, but
related scenarios. Two complications that frequently arise in practice are the
need to deal with highly irregular functional data and the need to acknowledge
and incorporate uncertainty in the inputs. We develop methodology to deal with
both complications. A key part of the approach utilizes a wavelet
representation of the functional data, applies a hierarchical version of the
scalar validation methodology to the wavelet coefficients, and transforms back,
to ultimately compare computer model output with field output. The generality
of the methodology is only limited by the capability of a combination of
computational tools and the appropriateness of decompositions of the sort
(wavelets) employed here. The methods and analyses we present are illustrated
with a test bed dynamic stress analysis for a particular engineering system.Comment: Published in at http://dx.doi.org/10.1214/009053607000000163 the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Heat-pulse measurements of sap flow in olives for automating irrigation: tests, root flow and diagnostics of water stress
26 páginas, 10 figuras, 1 tabla, 32 referencias.-- [email protected] compensation heat-pulse method for measuring sap flow is tested here in olive trees (Olea
europaea L.). We describe a rigorous three-way examination of the robustness of the technique for
this species, and examine the potential of the technique for an automatic control of the irrigation
system. Two tests were carried out using heat-pulse gear inserted into the stem of 12-year-old
‘Manzanilla’ olive trees. One test used forced-flow through a stem section, and the other involved
measured water uptake by an excised tree. The measured sap flow in these two tests was in
agreement with calculations from heat-pulse velocities when using a standard ‘wound correction’ to
account for the presence of the probes and the disruption to the sap flow. Thus, this technique for
monitoring transpiration can, we feel, be used with confidence in olives.
The third experiment was carried out in the field, where we analysed sap flow data from two 29-
year-old olive trees—one tree was under regular drip irrigation and the other was from dry-farming
conditions. We use measurements of sap flow in the trunk to examine the hydraulic functioning of
the tree, and to explore some diagnostics of water stress. Our heat-pulse measurements in the
irrigated olive tree exhibited a profile of sap flow that was weighted towards the outer xylem of the
tree trunk while the water-stressed trees in the field showed a profile of sap flow weighted towards
the centre of the trunk. The loss of hydraulic functioning in the outermost section of the vascular
system, as a result of water stress, we consider to be due both to stomatal control and to embolisms
in the xylem vessels.
The fourth experiment was also carried out in the field, in which sap flow measurements were
made at three locations in the trunk as well as in two roots of another 29-year-old olive tree. The
soil explored by each root, on opposite sides of the trunk, was differentially wetted by separate
irrigation of each side. Our data showed that the surface roots were able to absorb water immediately after wetting, despite a reasonably prolonged period of moderate drought. Root
activity quickly shifted to the regions where the soil had been wetted. A root in dry soil exhibited no
flow at night, whereas sap flows of about 0.02 l h 1 were measured around midnight in the root
drawing water from the wetter soil. Our observations suggest that the hydraulic behaviour of the
trunk and surface roots might be used as a diagnostic of the onset, or severity, of water stress. Here
there is not the imperative to replicate, for the prime goal is not transpiration estimation. Rather
interpretation of the diurnal dynamics is used to infer the onset, or severity of water stress.
The compensation heat-pulse seems a suitable technique for automatically controlling the
irrigation system of olives, and probably other trees, based either on the estimation of the short-time
dynamics of transpiration, or on changes in the hydraulic behaviour of the trees.The Comisión Interministerial de Ciencia y Tecnología of the
Spanish Ministry of Education and Science financial support this project.Peer reviewe
Heat-pulse measurements of sap flow in olives for automating irrigation: tests, root flow and diagnostics of water stress
26 páginas, 10 figuras, 1 tabla, 32 referencias.-- [email protected] compensation heat-pulse method for measuring sap flow is tested here in olive trees (Olea
europaea L.). We describe a rigorous three-way examination of the robustness of the technique for
this species, and examine the potential of the technique for an automatic control of the irrigation
system. Two tests were carried out using heat-pulse gear inserted into the stem of 12-year-old
‘Manzanilla’ olive trees. One test used forced-flow through a stem section, and the other involved
measured water uptake by an excised tree. The measured sap flow in these two tests was in
agreement with calculations from heat-pulse velocities when using a standard ‘wound correction’ to
account for the presence of the probes and the disruption to the sap flow. Thus, this technique for
monitoring transpiration can, we feel, be used with confidence in olives.
The third experiment was carried out in the field, where we analysed sap flow data from two 29-
year-old olive trees—one tree was under regular drip irrigation and the other was from dry-farming
conditions. We use measurements of sap flow in the trunk to examine the hydraulic functioning of
the tree, and to explore some diagnostics of water stress. Our heat-pulse measurements in the
irrigated olive tree exhibited a profile of sap flow that was weighted towards the outer xylem of the
tree trunk while the water-stressed trees in the field showed a profile of sap flow weighted towards
the centre of the trunk. The loss of hydraulic functioning in the outermost section of the vascular
system, as a result of water stress, we consider to be due both to stomatal control and to embolisms
in the xylem vessels.
The fourth experiment was also carried out in the field, in which sap flow measurements were
made at three locations in the trunk as well as in two roots of another 29-year-old olive tree. The
soil explored by each root, on opposite sides of the trunk, was differentially wetted by separate
irrigation of each side. Our data showed that the surface roots were able to absorb water immediately after wetting, despite a reasonably prolonged period of moderate drought. Root
activity quickly shifted to the regions where the soil had been wetted. A root in dry soil exhibited no
flow at night, whereas sap flows of about 0.02 l h 1 were measured around midnight in the root
drawing water from the wetter soil. Our observations suggest that the hydraulic behaviour of the
trunk and surface roots might be used as a diagnostic of the onset, or severity, of water stress. Here
there is not the imperative to replicate, for the prime goal is not transpiration estimation. Rather
interpretation of the diurnal dynamics is used to infer the onset, or severity of water stress.
The compensation heat-pulse seems a suitable technique for automatically controlling the
irrigation system of olives, and probably other trees, based either on the estimation of the short-time
dynamics of transpiration, or on changes in the hydraulic behaviour of the trees.The Comisión Interministerial de Ciencia y Tecnología of the
Spanish Ministry of Education and Science financial support this project.Peer reviewe
Design optimization of pixel sensors using device simulations for the phase-II CMS tracker upgrade
In order to address the problems caused by the harsh radiation environment during the high luminosity phase of the LHC (HL-LHC), all silicon tracking detectors (pixels and strips) in the CMS experiment will undergo an upgrade. And so to develop radiation hard pixel sensors, simulations have been performed using the 2D TCAD device simulator, SILVACO, to obtain design parameters. The effect of various design parameters like pixel size, pixel depth, implant width, metal overhang, p-stop concentration, p-stop depth and bulk doping density on the leakage current and critical electric field are studied for both non-irradiated as well as irradiated pixel sensors. These 2D simulation results of planar pixels are useful for providing insight into the behaviour of non-irradiated and irradiated silicon pixel sensors and further work on 3D simulation is underway. © 2015 Elsevier B.V
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