257 research outputs found
Detector of alpha particles and x-rays operating in ambient air in pulse counting mode or/and with gas amplification
Ionization chambers working in ambient air in current detection mode are
widely used in several applications such as smoke detection, dosimetry,
therapeutic beam monitoring and cetera. The aim of this work was to investigate
if gaseous detectors can operate in ambient air in pulse counting mode as well
as with gas amplification. . To investigate the feasibility of this method two
types of open- end gaseous detectors were build and successfully tested. The
first one was a single wire or multiwire cylindrical geometry detector
operating in pulse mode at a gas gain of 1. The second type alpha detector was
an innovative GEM-like detector with resistive electrodes operating in air in
avalanche mode at high gas gains (up to 10E4). A detailed comparison between
these two detectors is given as well as comparison with the commercially
available alpha detectors. The main advantages of gaseous detectors operating
in air in a pulse detection mode are their simplicity, low cost and high
sensitivity. One of the possible applications of these new detectors is alpha
particle background monitors which, due to their low cost can find wide
application not only in houses, but in public areas: airports, railway station
and so on
Progress in the development of a S RETGEM-based detector for an early forest fire warning system
In this paper we present a prototype of a Strip Resistive Thick GEM
photosensitive gaseous detector filled with Ne and ethylferrocene vapours at a
total pressure of 1 atm for an early forest fire detection system. Tests show
that it is one hundred times more sensitive than the best commercial
ultraviolet flame detectors and therefore, it is able to reliably detect a
flame of 1.5x1.5x1.5 m3 at a distance of about 1km. An additional and unique
feature of this detector is its imaging capability, which in combination with
other techniques, may significantly reduce false fire alarms when operating in
an automatic mode.
Preliminary results conducted with air filled photosensitive gaseous
detectors are also presented. The approach main advantages include both the
simplicity of manufacturing and affordability of construction materials such as
plastics and glues specifically reducing detector production cost. The
sensitivity of these air filled detectors at certain conditions may be as high
as those filled with Ne and EF. Long term test results of such sealed detectors
indicate a significant progress in this direction.
We believe that our detectors utilized in addition to other flame and smoke
sensors will exceptionally increase the sensitivity of forest fire detection
systems. Our future efforts will be focused on attempts to commercialize such
detectors utilizing our aforementioned findings.Comment: Presented at the International Conference on Micropattern gaseous
detectors, Crete, Greece, June 200
Performance of wire-type Rn detectors operated with gas gain in ambient air in view of its possible application to early earthquake predictions
We describe a detector of alpha particles based on wire type counters
(single-wire and multiwire) operating in ambient air at high gas gains
(100-1000). The main advantages of these detectors are: low cost, robustness
and ability to operate in humid air. The minimum detectable activity achieved
with the multiwire detector for an integration time of 1 min is 140 Bq per m3,
which is comparable to that featured by commercial devices. Owing to such
features the detector is suited for massive application, for example for
continuous monitoring of Rn or Po contaminations or, as discussed in the paper,
its use in a network of Rn counters in areas affected by earth-quakes in order
to verify, on a solid statistical basis, the envisaged correlation between the
sudden Rn appearance and a forthcoming earthquake
The classification of irreducible admissible mod p representations of a p-adic GL_n
Let F be a finite extension of Q_p. Using the mod p Satake transform, we
define what it means for an irreducible admissible smooth representation of an
F-split p-adic reductive group over \bar F_p to be supersingular. We then give
the classification of irreducible admissible smooth GL_n(F)-representations
over \bar F_p in terms of supersingular representations. As a consequence we
deduce that supersingular is the same as supercuspidal. These results
generalise the work of Barthel-Livne for n = 2. For general split reductive
groups we obtain similar results under stronger hypotheses.Comment: 55 pages, to appear in Inventiones Mathematica
Study on Public Participation in Urban Planning in China
公众参与城市规划是政治民主化的重要体现,有利于实现规划的科学性,确保规划的有效实施,其最终目的是通过对城市规划中存在的非市场失灵的补充与修正,保证城市规划的公平性与公正性,实现公众利益的最大化,促进社会发展。本文综合运用了文献资料法、比较分析法和实证研究法等多种研究方法,力图对我国城市规划中的公众参与进行全面、系统而深入的分析和探讨,以期为我国公众参与城市规划作出一点有价值的研究。全文主体共分为三个部分:第一部分:比较分析了我国不同时期对城市规划概念的不同理解,总结了我国城市规划的变化趋势,论述了城市规划的含义;通过分析《城市规划法》,论述了城市规划的基本属性——公共政策属性;论述了城市规划的...Public participation in urban planning is the important embodiment of Politics democratization, is also the guarantee of making urban planning scientific and putting it into practice successfully. The final goal of public participation in urban planning is according to the supplement and revision in view of non-market failure which exists to urban planning itself, guaranteeing the fairness of urba...学位:管理学硕士院系专业:公共事务学院公共管理系_行政管理学号:20040601
Computations in non-commutative Iwasawa theory
We study special values of L-functions of elliptic curves over Q twisted by
Artin representations that factor through a false Tate curve extension
. In this setting, we explain how to
compute L-functions and the corresponding Iwasawa-theoretic invariants of
non-abelian twists of elliptic curves. Our results provide both theoretical and
computational evidence for the main conjecture of non-commutative Iwasawa
theory.Comment: 60 pages; with appendix by John Coates and Ramdorai Sujath
Urinary peptidome analyses for the diagnosis of chronic kidney disease in dogs
Chronic kidney disease (CKD) is clinically important in canine medicine. Current diagnostic tools lack sensitivity for detection of subclinical CKD. The aim of the present study was to evaluate urinary peptidome analysis for diagnosis of CKD in dogs. Capillary electrophoresis coupled to mass spectrometry analysis demonstrated presence of approximately 5400 peptides in dog urine. Comparison of urinary peptide abundance of dogs with and without CKD led to the identification of 133 differentially excreted peptides (adjusted P for each peptide <0.05). Sequence information was obtained for 35 of these peptides. This 35 peptide subset and the total group of 133 peptides were used to construct two predictive models of CKD which were subsequently validated by researchers masked to results in an independent cohort of 20 dogs.
Both models diagnosed CKD with an area under the receiver operating characteristic (ROC) curve of 0.88 (95% confidence intervals [CI], 0.72–1.0). Most differentially excreted peptides represented fragments of collagen I, indicating possible association with fibrotic processes in CKD (similar to the equivalent human urinary peptide CKD model, CKD273). This first study of the urinary peptidome in dogs identified peptides that were associated with presence of CKD. Future studies are needed to validate the utility of this model for diagnosis and prediction of progression of canine CKD in a clinical setting
Elliptic Curves over Real Quadratic Fields are Modular
We prove that all elliptic curves defined over real quadratic fields are
modular.Comment: 38 pages. Magma scripts available as ancillary files with this arXiv
versio
El proyecto genómico del hongo Ophiostoma
The Canadian Ophiostoma Genome Project, which was initiated in 2001, is a collaborative effort between research teams in four different universities. Its general objective is to conduct a large-scale identification and analysis of genes controlling important aspects of the life cycle of Ophiostomatoid fungi. To this end, several expressed sequence tag (EST) libraries were obtained for the Dutch elm disease pathogen Ophiostoma novo-ulmi and the sapstainer O. piceae, following partial, single-pass automated sequencing of complementary DNA clones. The largest EST library, prepared from yeast like cells of O. novo-ulmi grown at 24 °C, contains over 3,400 readable sequences and serves as a general reference library for Ophiostomatoid fungi. Smaller, specific EST libraries were constructed from mycelia of O. novo-ulmi grown at suboptimal temperatures, from perithecia formed in laboratory crosses, as well as from O. piceae grown on different carbon sources. Ongoing bioinformatic searches in public databases have so far identified over 750 Ophiostoma unique ESTs which show significant homology with other fungal genes of known function, although a high proportion of Ophiostoma ESTs are either orphans (no match to any known gene) or show homology to genes of unknown function. In addition to EST analysis, differential expression of selected genes and structural genomics are also being studied.El programa canadiense sobre el genoma de Ophiostoma, iniciado en 2001, es una colaboración entre equipos de investigación de cuatro universidades diferentes. Su objetivo general es el desarrollo de la identificación y análisis a gran escala de los genes que controlan algunos aspectos importantes del ciclo vital de los hongos de Ophiostoma. Con este fin, se ha obtenido diversas bibliotecas de marcadores de secuencias expresadas (bibliotecas EST) para la el patógeno de la grafiosis Ophiostoma novo-ulmi y para el hongo de tinción vascular O. piceae, seguido de una secuenciación automática parcial de un único paso de clones complementarios de ADN. La mayor biblioteca EST, preparada a partir de conidios de O. novo-ulmi cultivadas a 24 ºC, contiene más de 3.400 secuencias legíbles, y sirve como biblioteca de referencia para los hongos de Ophiostoma. Se han desarrollado bibliotecas específicas menores a partir de micelios de O. novo-ulmi cultivados a temperaturas sub-óptimas, a partir de los peritecios formados en cruces realizados en laboratorio, así como a partir de O. piceae cultivado en distintas fuentes de carbón. Las búsquedas bioinformáticas en bases de datos públicas han permitido identificar hasta ahora más de 750 EST exclusivos de Ophiostoma, lo que muestra una significativa homología con otros genes fúngicos de función conocida, aunque una alta proporción de los EST de Ophiostoma son o bien huérfanos (no relacionados con ningún gen conocido), o bien muestran homología con genes cuya función es desconocida. Además del análisis EST, la expresión diferencial de genes seleccionados y la estructura genómica están siendo también estudiadas
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