Search results for "Mask"

Detection performance of normal cats and those lacking areas 17 and 18: a behavioral approach to analyse pattern recognition deficits.

1986

The ability of cats to discriminate between two geometrical outline patterns in the presence of superimposed Gaussian visual noise was tested before and after bilateral removal of cortical area 17 and parts of area 18. The detection probability PD was measured as a function of the signal-to-noise ratio for the parameters: noise bandwidth, spatial frequency content and rate of movement of patterns. In both normal and lesioned cats a broadband noise was found to be most effective in masking the large patterns while two other types of noise, a medium frequency noise and a high frequency noise had little or no masking effect. For recognition of the smaller patterns in normal cats the medium fre…

Fabrication and characterization of tuned Gaussian mirrors for the visible and the near infrared

1988

A thin-film technique has been developed for vacuum fabrication of mirrors with Gaussian reflectivity profiles. Samples with diameters from 2 to 8 mm and assigned maximum reflectivities for visible or near-IR wavelengths have been made and their optical properties evaluated. By properly choosing both the geometry of the evaporation source and the masking system, one can obtain quasi-Gaussian or super-Gaussian reflectivity profiles.

Improving Isolation of Blindly Separated Sources Using Time-Frequency Masking

2008

A refinement technique based on time-frequency masking is proposed to improve source isolation in blind audio source separation algorithms. The refinement technique uses an energy-normalized source-to-interference ratio in order to identify and eliminate interfering energy from the extracted sources. Some examples using this refinement method with different separation algorithms are discussed. The results show that source isolation can be significantly enhanced with negligible degradation of the separated sources.

V1 non-linear properties emerge from local-to-global non-linear ICA

2006

It has been argued that the aim of non-linearities in different visual and auditory mechanisms may be to remove the relations between the coefficients of the signal after global linear ICA-like stages. Specifically, in Schwartz and Simoncelli (2001), it was shown that masking effects are reproduced by fitting the parameters of a particular non-linearity in order to remove the dependencies between the energy of wavelet coefficients. In this work, we present a different result that supports the same efficient encoding hypothesis. However, this result is more general because, instead of assuming any specific functional form for the non-linearity, we show that by using an unconstrained approach…

2019

Previous research has consistently shown that for sounds varying in intensity over time, the beginning of the sound is of higher importance for the perception of loudness than later parts (primacy effect). However, in all previous studies, the target sounds were presented in quiet, and at a fixed average sound level. In the present study, temporal loudness weights for a time-varying narrowband noise were investigated in the presence of a continuous bandpass-filtered background noise and the average sound levels of the target stimuli were varied across a range of 60 dB. Pronounced primacy effects were observed in all conditions and there were no significant differences between the temporal w…

Perception of mixtures of odorants and tastants: sensory and analytical points of view

2017

Perception of mixtures of odorants and tastants: sensory and analytical points of view

Feminisms un maskulīnisms

2016

„Feminisms un maskulīnisms” ir pētījums par maskulīnisma, feminisma un to kustību attīstību un konfliktu. Darbā autore analizē iemeslus, kādēļ divas ideoloģijas un to kustības, kas postulē nepieciešamību nodrošināt līdztiesību un vienlīdzīgas iespējas sievietēm un vīriešiem, nav spējušas rast kopīgu valodu un to starpā veidojas regulāri konflikti. Autore analizē, vai iemesls šim konfliktam neslēpjas maskulīnisma un tā sociālo kustību antifeministiskajā nostājā. Darba ietvaros šī konflikta praktiskai analīzei autore pielieto deskriptīvo gadījuma analīzes metodi, pētot „Gamer Gate” konfliktu, kura laikā izcēlās visaptverošs disputs, kas radīja ne vien ietekmi uz kultūru, bet arī sabiedrību un…

Aerosol filtration efficiency of household materials for homemade face masks: Influence of material properties, particle size, particle electrical ch…

2020

As a consequence of the COVID-19 pandemic caused by the SARS-CoV-2 virus, the widespread daily use of face masks is promoted worldwide. Particle-size dependent filtration efficiencies (FE; dp = 30 nm–10 µm), applying a particle counting approach, and additionally pressure drops (Δp) were determined for 44 samples of household materials and several medical masks. Huge FE differences were found between sample materials and for different particle sizes, spanning from <10% up to almost 100%. Minimum FE were determined for dp = 50–500 nm particles with significantly larger values for dp = 30 nm particles and especially for those with dp > 2.5 µm. Measurements at different numbers of layers…

Intregrating metallic wiring with three-dimensional polystyrene colloidal crystals using electron-beam lithography and three-dimensional laser lithog…

2017

We demonstrate a method to fabricate narrow, down to a few micron wide metallic leads on top of a three-dimensional colloidal crystal self-assembled from polystyrene (PS) nanospheres of diameter 260 nm, using electron-beam lithography. This fabrication is not straightforward due to the fact that PS nanospheres cannot usually survive the harsh chemical treatments required in the development and lift-off steps of electron-beam lithography. We solve this problem by increasing the chemical resistance of the PS nanospheres using an additional electron-beam irradiation step, which allows the spheres to retain their shape and their self-assembled structure, even after baking to a temperature of 16…

All-organic electro-optic waveguide modulator comprising SU-8 and nonlinear optical polymer

2017

Institute of Solid State Physics, University of Latvia (SJZ/2016/26); Ministry of Education and Science, Republic of Latvia (MultIfunctional Materials and composItes, photonicS and nanotechnology (IMIS2)). We acknowledge Dr. Anatolijs Sarakovskis at Institute of Solid State Physics for the XPS measurements.