265 research outputs found
GPS Multipath Detection in the Frequency Domain
Multipath is among the major sources of errors in precise positioning using
GPS and continues to be extensively studied. Two Fast Fourier Transform
(FFT)-based detectors are presented in this paper as GPS multipath detection
techniques. The detectors are formulated as binary hypothesis tests under the
assumption that the multipath exists for a sufficient time frame that allows
its detection based on the quadrature arm of the coherent Early-minus-Late
discriminator (Q EmL) for a scalar tracking loop (STL) or on the quadrature (Q
EmL) and/or in-phase arm (I EmL) for a vector tracking loop (VTL), using an
observation window of N samples. Performance analysis of the suggested
detectors is done on multipath signal data acquired from the multipath
environment simulator developed by the German Aerospace Centre (DLR) as well as
on multipath data from real GPS signals. Application of the detection tests to
correlator outputs of scalar and vector tracking loops shows that they may be
used to exclude multipath contaminated satellites from the navigation solution.
These detection techniques can be extended to other Global Navigation Satellite
Systems (GNSS) such as GLONASS, Galileo and Beidou.Comment: 2016 European Navigation Conference (ENC 2016), May 2016, Helsinki,
Finland. Proceedings of the 2016 European Navigation Conference (ENC 2016
Le problĂšme de lâeau Ă Fogo (archipel du Cap-Vert)
Fogo se distingue des autres Ăźles de lâarchipel cap-verdien parce quâelle est associĂ©e Ă un stratovolcan de forme en plan circulaire â dâenviron 25 km de diamĂštre â culminant Ă 2 800 m, mais, comme les autres, elle participe de la mĂȘme incertitude pluviomĂ©trique et a subi, tout au long de son histoire longue de cinq siĂšcles, des ajustements morbides que nâaurait pas dĂ©savouĂ©s Malthus. Il a fallu attendre les annĂ©es 1950 pour que les envois de fonds par les Ă©migrĂ©s et les interventions des organismes internationaux mettent un terme Ă la rĂ©currence de famines meurtriĂšres. En lâabsence de correctifs, toute carence pluviomĂ©trique rĂ©duit les niveaux de production de la nourriture de base, le maĂŻs, au-dessous des besoins de survie, et cette culture pluviale constitue une vĂ©ritable loterie. Le caractĂšre erratique de la pluviomĂ©trie dĂ©coule de lâinefficacitĂ© pluviale du flux ultra-dominant (lâalizĂ© ocĂ©anique), porteur de stratus et de rosĂ©e cĂŽtĂ© nord, et de lâextrĂȘme irrĂ©gularitĂ© des interventions de lâĂ©quateur mĂ©tĂ©orologique. Celui-ci avance parfois jusquâĂ lâarchipel. Mais, lâessentiel des chutes provient de remontĂ©es âponctuellesâ dâair de la mousson dĂ©clenchĂ©es par des mĂ©canismes dâorigine extratropicale : en saison ce sont les lignes de grains qui lâinstabilisent ; hors saison ce sont les circulations de style âheugâ qui le mobilisent, Ă haut niveau. Orographie et trajectoires des flux les plus efficaces expliquent le net avantage du versant nord-est.Unlike the other islands Fogo consists of a single stratovolcano, which explains why it has the shape of a nearly spherical cone about 25 km in diameter with a 2,800 m-peak at its summit. From the earliest years more than five centuries ago, its history has been punctuated by periodic and catastrophic droughts and famines. These Malthusian disasters have repetitively lowered the number of its inhabitants to a more sustainable level. During the last decades private remittances from abroad and international assistance have lightened the critical reliance of an increasing population upon corn production which, due to the lack of irrigated fields, remains a lottery. The greatest climatic constraint is the erratic occurrence of rain during the agricultural season between July-August and October-November. This erratic pluviometry results from the lack of rain with the most frequent flux (the oceanic trade winds only bringing stratus or dew on the northern side) and from the weak direct rĂŽle of ITCZ (the latter rarely reaching the archipelago), but, most of the rain is brought by localized northward pulses of monsoon driven by extratropical mechanisms. During the rainy season there are Squall Lines triggering its instability ; out of the season the âmango rainsâ result from the effects of polar Trough Lines. Orography and flux trajectories account for the obvious advantage of the north-eastern slopes.Fogo destaca-se das outras ilhas do arquipĂ©lago cabo-verdiano por estar associada a um estratovulcĂŁo que explica a forma de cone quase esfĂ©rico - com cerca de 25 km de diĂąmetro - culminando a 2800 m, mas, tal como as outras, beneficia da mesma incerteza pluviomĂ©trica e sofreu ao longo dos seus cinco sĂ©culos de histĂłria ajustamentos mĂłrbido dignos de Malthus. Foi preciso esperar pelos anos 1950 para que os envios de fundos de emigrados e as intervençÔes dos organismos internacionais acabem com a repetição de fome homicida. Na falta de correctivos, toda carĂȘncia pluviomĂ©trica reduz os nĂveis de produção da comida bĂĄsica, o milho, abaixo das necessidades de sobrevivĂȘncia, e esta cultura em sequeiro torna-se uma verdadeira loteria. O carĂĄcter errĂĄtico da pluviometria decorre da ineficĂĄcia pluvial do fluxo mais frequente (o vento alĂsio oceĂąnico), portador de estratos e orvalho do lado norte, e da extrema irregularidade das intervençÔes da zona de convergĂȘncia intertropical. Este avança Ă s vezes atĂ© ao arquipĂ©lago. Mas maior parte da chuva provem de subidas pontuais de ar da monção provocadas por mecanismos de origem extratropical : durante a Ă©poca da chuva a frente de rajadas ativa a sua instabilidade ; fora da Ă©poca sĂŁo as circulaçÔes tipo âheugâ que o mobilizam, a todos nĂveis. Orografia e trajectĂłrias dos fluxos mais eficazes explicam a nĂtida vantagem da encosta nordeste
A Comparison of Treatment-Seeking Behavioral Addiction Patients with and without Parkinson's Disease
The administration of dopaminergic medication to treat the symptoms of Parkinson's disease (PD) is associated with addictive behaviors and impulse control disorders. Little is known, however, on how PD patients differ from other patients seeking treatments for behavioral addictions. The aim of this study was to compare the characteristics of behavioral addiction patients with and without PD. N = 2,460 treatment-seeking men diagnosed with a behavioral addiction were recruited from a university hospital. Sociodemographic, impulsivity [Barratt Impulsiveness Scale (BIS-11)], and personality [Temperament and Character Inventory-Revised (TCI-R)] measures were taken upon admission to outpatient treatment. Patients in the PD group were older and had a higher prevalence of mood disorders than patients without PD. In terms of personality characteristics and impulsivity traits, PD patients appeared to present a more functional profile than PD-free patients with a behavioral addiction. Our results suggest that PD patients with a behavioral addiction could be more difficult to detect than their PD-free counterparts in behavioral addiction clinical setting due to their reduced levels of impulsivity and more standard personality traits. As a whole, this suggests that PD patients with a behavioral addiction may have different needs from PD-free behavioral addiction patients and that they could potentially benefit from targeted interventions
A comparison of treatment-seeking behavioral addiction patients with and without parkinson's disease
The administration of dopaminergic medication to treat the symptoms of Parkinson's disease (PD) is associated with addictive behaviors and impulse control disorders. Little is known, however, on how PD patients differ from other patients seeking treatments for behavioral addictions. The aim of this study was to compare the characteristics of behavioral addiction patients with and without PD. N = 2,460 treatment-seeking men diagnosed with a behavioral addiction were recruited from a university hospital. Sociodemographic, impulsivity [Barratt Impulsiveness Scale (BIS-11)], and personality [Temperament and Character Inventory-Revised (TCI-R)] measures were taken upon admission to outpatient treatment. Patients in the PD group were older and had a higher prevalence of mood disorders than patients without PD. In terms of personality characteristics and impulsivity traits, PD patients appeared to present a more functional profile than PD-free patients with a behavioral addiction. Our results suggest that PD patients with a behavioral addiction could be more difficult to detect than their PD-free counterparts in behavioral addiction clinical setting due to their reduced levels of impulsivity and more standard personality traits. As a whole, this suggests that PD patients with a behavioral addiction may have different needs from PD-free behavioral addiction patients and that they could potentially benefit from targeted interventions
Red Clump Morphology as Evidence Against a New Intervening Stellar Population as the Primary Source of Microlensing Toward the LMC
We examine the morphology of the color-magnitude diagram (CMD) for core
helium-burning (red clump) stars to test the recent suggestion by Zaritsky &
Lin (1997) that an extension of the red clump in the Large Magellanic Cloud
(LMC) toward brighter magnitudes is due to an intervening population of stars
that is responsible for a significant fraction of the observed microlensing
toward the LMC. Using our own CCD photometry of several fields across the LMC,
we confirm the presence of this additional red clump feature, but conclude that
it is caused by stellar evolution rather than a foreground population. We do
this by demonstrating that the feature (1) is present in all our LMC fields,
(2) is in precise agreement with the location of the blue loops in the
isochrones of intermediate age red clump stars with the metallicity and age of
the LMC, (3) has a relative density consistent with stellar evolution and LMC
star formation history, and (4) is present in the Hipparcos CMD for the solar
neighborhood where an intervening population cannot be invoked. Assuming there
is no systematic shift in the model isochrones, which fit the Hipparcos data in
detail, a distance modulus of provides the best fit to our
dereddened CMD.Comment: 21 pages LaTex (aaspp4.sty), including three tables and 9 figures (1
is .ps, 8 are .gif). Accepted for publication by Astronomical Journal on
March 16, 1998. One error corrected and major revisions now lead to an even
stronger argument for the stellar evolutionary origin of features in the LMC
color magnitude diagram, claimed by others to be an intervening stellar
population and major source of microlensing optical depth toward the LM
Wild-type VHL Clear Cell Renal Cell Carcinomas Are a Distinct Clinical and Histologic Entity: A 10-Year Follow-up
International audienceBackground: Clear cell renal cell carcinoma (ccRCC) is an aggressive tumor with 50% risk of metastases at initial diagnosis or at follow-up. An inactivation of the tumor-suppressor gene von Hippel-Lindau (VHL) is present in >70% of sporadic cases by two of three different mechanisms: locus deletion, gene mutation, or promoter hypermethylation. Objective: To correlate the complete status of the VHL gene with clinical and pathologic criteria. Design, setting, and participants We retrospectively included 98 patients with ccRCC who underwent surgery between 2002 and 2005. VHL gene deletions (71 of 98; 72.4%), mutations (68 of 98; 69.4%), and promoter hypermethylations (13 of 98; 13.3%) were screened by gene copy analysis, gene sequencing, and methylation-specific multiplex ligation-dependent probe amplification, respectively. Outcome measurements and statistical analysis Relationships between VHL subgroups and the studied criteria were analyzed using chi-square and Student t tests. Survival was analyzed with the log-rank test and Kaplan-Meier curves. Results and limitations: Compared with ccRCCs with two events (66.3%), tumors with no or one genetic event (33.6%) were associated with a higher nuclear grade IV (p = 0.02), metastases (p = 0.04), sarcomatoid component (p = 0.01), dense lymphocyte infiltrate (p = 0.013), and vascular endothelial growth factor overexpression (>30%) (p = 0.003), which was also an independent factor after multivariate analysis. Furthermore, wild-type VHL tumors (no inactivating event, 11.2%) were associated with nodal involvement (p = 0.019), and patients with this type of tumor had a specific survival of 33 mo compared with patients with ccRCCs having one or two VHL inactivating events (107 mo; p = 0.016). The retrospective design with small number of wild-type tumors was a limitation of this work. Conclusions: This long-term study (10-yr clinical follow-up) confirms that ccRCCs with wild-type VHL are highly aggressive tumors that need to be formally identified. Patient summary Among activated VHL tumors, the wild-type subgroup defines an aggressive phenotype with worse survival rates, suggesting that these tumors must be more thoroughly screene
Parkinson's disease and iatrogenic impulsive-compulsive behaviors: A case/non-case study to build a complete model of individual vulnerability
Background and aims: Parkinsonâs disease (PD) is one of the most prevalent neurodegenerative diseases. First-line medications consist of drugs that act by counteracting dopamine deficiency in the basal ganglia. Unfortunately, iatrogenic impulsive-compulsive behaviors (ICBs) can occur in up to 20% of PD patients over the course of their illness. ICBs must be considered multifactorial disorders that reflect the interactions of the medication with an individualâs vulnerability and the underlying neurobiology of PD. We aimed to explore the predictive genetic, psychopathological and neurological factors involved in the development of ICBs in PD patients by building a complete model of individual vulnerability. Methods: The PARKADD study was a case/non-case study. A total of 225 patients were enrolled (âICBâ group, N 5 75; âno ICBâ group, N 5 150), and 163 agreed to provide saliva samples for genetic analysis. Sociodemographic, neurological and psychiatric characteristics were assessed, and genotyping for the characterization of polymorphisms related to dopaminergic and opioid systems was performed. Results: Factors associated with âICBsâ were younger age of PD onset, personal history of ICB prior to PD onset and higher scores on the urgency and sensation seeking facets of impulsivity. No gene variant was significantly associated, but the association with the opioid receptor mu 1 (OPRM1) rs1799971 polymorphism was close to significance. Discussion and conclusions: The influence of gene-environment interactions probably exists, and additional studies are needed to decipher the possible role of the opioid system in the development of ICBs in PD patients
Testing for the Dual-Route Cascade Reading Model in the Brain: An fMRI Effective Connectivity Account of an Efficient Reading Style
Neuropsychological data about the forms of acquired reading impairment provide a strong basis for the theoretical framework of the dual-route cascade (DRC) model which is predictive of reading performance. However, lesions are often extensive and heterogeneous, thus making it difficult to establish precise functional anatomical correlates. Here, we provide a connective neural account in the aim of accommodating the main principles of the DRC framework and to make predictions on reading skill. We located prominent reading areas using fMRI and applied structural equation modeling to pinpoint distinct neural pathways. Functionality of regions together with neural network dissociations between words and pseudowords corroborate the existing neuroanatomical view on the DRC and provide a novel outlook on the sub-regions involved. In a similar vein, congruent (or incongruent) reliance of pathways, that is reliance on the word (or pseudoword) pathway during word reading and on the pseudoword (or word) pathway during pseudoword reading predicted good (or poor) reading performance as assessed by out-of-magnet reading tests. Finally, inter-individual analysis unraveled an efficient reading style mirroring pathway reliance as a function of the fingerprint of the stimulus to be read, suggesting an optimal pattern of cerebral information trafficking which leads to high reading performance
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