scholarly journals Explaining brightness illusions using spatial filtering and local response normalization

2007 ◽  
Vol 47 (12) ◽  
pp. 1631-1644 ◽  
Author(s):  
Alan E. Robinson ◽  
Paul S. Hammon ◽  
Virginia R. de Sa
Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 577
Author(s):  
Bartosz Janaszek ◽  
Marcin Kieliszczyk ◽  
Anna Tyszka-Zawadzka ◽  
Paweł Szczepański

In this paper we investigate transmittance and reflectance spectra of multilayer hyperbolic metamaterials in the presence of strong spatial dispersion. Our analysis revealed a number of intriguing optical phenomena, which cannot be predicted with the local response approximation, such as total reflectance for small angles of incidence or multiple transmittance peaks of resonant character (instead of the respective local counterparts, where almost complete transparency is predicted for small angles of incidence and the broad-angle transparency can be observed within a range of larger angles of incidence). We believe that the observed effects may serve as a working principle in a number of new potential applications, such as spatial filtering, biosensing, or beam steering.


2012 ◽  
Vol 3 (4) ◽  
pp. 153-156
Author(s):  
A.Rajamani A.Rajamani ◽  
◽  
Dr.V.Krishnaveni Dr.V.Krishnaveni

Author(s):  
M. E. Shevchenko ◽  
A. V. Gorovoy ◽  
S. N. Solovyov

The paper considers the spatial filtering methods of signals with spectrum overlapping under conditions of a priori uncertainty of the directions of arrival from radio sources. The estimates of the directions of signals arrival obtained by ESPRIT or MUSIC are used in order to build a spatial filter. It is shown that when using ESPRIT, unlike MUSIC, an additional calculations of filter coefficients based on estimates of the directions of signals arrival are not required, and the quadrature components of the signals are formed simultaneously with estimates of the direction of their arrival. The probability of error performances of minimum shift keying signals which were divided by spatial filtering on the basis of ESPRIT and MUSIC using seven-element circular and angular antenna arrays are given.


2021 ◽  
pp. 009145092110025
Author(s):  
Ali Unlu ◽  
Fatih Demiroz ◽  
Tuukka Tammi ◽  
Pekka Hakkarainen

Drug consumption rooms (DCRs) have been established to reach high-risk people who use drugs (PWUDs) and reduce drug-associated harm. Despite effectiveness, their establishment requires strong advocacy and efforts since moral perspectives tend to prevail over health outcomes in many countries. DCRs have generally emerged as a local response to inadequate central government policy. Likewise, the initiative of the Municipality of Helsinki in 2018 opened up a discussion between central government, society, and local actors in Finland. This would be the first DCR in Finland, which makes the policy process and the progress of the initiative interesting for analysis. In this article, the identification of agents, structures of interactions, environmental challenges, and policy opportunities are analyzed within the framework of complexity theory. Our results show that the initiative faces policy barriers that have mainly arisen from the conceptualization of DCRs in moral frameworks that result in the prolongation of political and professional actors to take a position on DCRs.


2021 ◽  
Vol 6 (1) ◽  
pp. e000733
Author(s):  
Astrid Muyldermans ◽  
Maria Bjerke ◽  
Thomas Demuyser ◽  
Deborah De Geyter ◽  
Ingrid Wybo ◽  
...  

Background/aimsSARS-CoV-2 is highly contagious. More evidence concerning extrapulmonary transmission routes such as the eyes is urgently needed. Although the humoral immune response is important in the viral containment, the local response in tears has not yet been studied. The aim of our study was twofold: to assess the prevalence of both SARS-CoV-2 RNA and antibodies in tear fluid.MethodsIn a first series, nasopharyngeal sampling and tear sampling by Schirmer test strips were performed in 26 acutely ill patients with COVID-19 to assess the presence of SARS-CoV-2 RNA by reverse transcription PCR. In a second series, IgG and IgA responses to SARS-CoV-2 spike protein in serum and tear fluid of convalescent individuals (n=22) were compared with control individuals (n=15) by ELISA.ResultsSARS-CoV-2 RNA was detected in tears of 7/26 (26.9%) patients with COVID-19. None of them had ocular symptoms. Convalescent individuals displayed a significant higher ratio of IgG (p<0.0001) and IgA (p=0.0068) in tears compared with control individuals. A sensitivity of 77.3% and specificity of 93.3% was observed for IgG, and 59.1% and 100% for IgA.ConclusionsOur results demonstrate the presence of SARS-CoV-2 RNA and a local IgG and IgA immune response in tear fluid. These data confirm the possibility of SARS-CoV-2 transmission through tear fluid and the importance of the eye as a first defence against SARS-CoV-2, indicating the potential of tears as a non-invasive surrogate for serum in monitoring the host immune response.


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