873,148 research outputs found
The Visible Spectrum
Today, the national environmental movement is entering a new phase, led by new players, just as the still young environmental protection movement is becoming more politically influential at the local level. The political power of the environmental justice and equity movement and its links with racial and social justice organizations makes its potential impact reach far beyond “NIMBY” (not-in-my-backyard) protests. NIMBY was the first wave of quasi-organized local environmental protests, usually rooted in a single issue. Environmental justice is the next wave, drawing in a broader range of concerns. The focus of this analysis is on how environmental issues are manifesting themselves in the Greenpoint/Williamsburg area of Brooklyn. The experience of West Harlem in opposing the operation of the North River Treatment Plant is also examined. In both instances the social class and ethnic identity of these grassroots environmentalists significantly differ from those of the environmental activists of previous generations
In a Different Light
This module develops the understanding that visible light is composed of a spectrum of colors of light from red to violet, extends the concept of a spectrum to include non-visible light through discovery, and develops tools and strategies for student inquiry. Educational levels: Middle school, High school
Biometric presentation attack detection: beyond the visible spectrum
The increased need for unattended authentication in
multiple scenarios has motivated a wide deployment of biometric
systems in the last few years. This has in turn led to the
disclosure of security concerns specifically related to biometric
systems. Among them, presentation attacks (PAs, i.e., attempts
to log into the system with a fake biometric characteristic or
presentation attack instrument) pose a severe threat to the
security of the system: any person could eventually fabricate
or order a gummy finger or face mask to impersonate someone
else. In this context, we present a novel fingerprint presentation
attack detection (PAD) scheme based on i) a new capture device
able to acquire images within the short wave infrared (SWIR)
spectrum, and i i) an in-depth analysis of several state-of-theart
techniques based on both handcrafted and deep learning
features. The approach is evaluated on a database comprising
over 4700 samples, stemming from 562 different subjects and
35 different presentation attack instrument (PAI) species. The
results show the soundness of the proposed approach with a
detection equal error rate (D-EER) as low as 1.35% even in a
realistic scenario where five different PAI species are considered
only for testing purposes (i.e., unknown attacks
Dual-band, double-negative, polarization-independent metamaterial for the visible spectrum
We present the first dual-band negative index metamaterial that operates in
the visible spectrum. The optimized four-functional-layer metamaterial
structure exhibits the first double-negative (i.e., simultaneously negative
permittivity and permeability) band in the red region of the visible spectrum
with a figure of merit of 1.7 and the second double-negative band in the green
region of the visible spectrum with a figure of merit of 3.2. The optical
behavior of the proposed structure is independent of the polarization of the
incident field. This low-loss metamaterial structure can be treated as a
modified version of a fishnet metamaterial structure with an additional metal
layer of different thickness in a single functional layer. The additional metal
layer extends the diluted plasma frequency deep into the visible spectrum above
the second order magnetic resonance of the structure, hence provides a dual
band operation with simultaneously negative effective permittivity and
permeability. Broadband metamaterials with multiple negative index bands may be
possible with the same technique by employing higher order magnetic resonances.
The structure can be fabricated with standard microfabrication techniques that
have been used to fabricate fishnet metamaterial structures.Comment: 26 Pages, 6 Figures, 2 Tables, 2 Medi
Surface-enhanced Raman spectroscopy of DNA bases
A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS spectrum new lines, not visible in the solution spectrum, appear while some lines visible in the solution spectrum are not enhanced to a detectable level and are therefore not seen in SERS. The relative intensities are changed owing to an apparently vibration-dependent enhancement factor. A line-broadening effect occurs for most lines except carbonyl stretching vibrations in cytosine and thymine. All SERS spectra show increased contributions of bending vibrations and side-chain groups. In particular, amino group vibrations in adenine and cytosine are clearly visible. Comparison of the shape and intensity of the carbonyl stretching vibrations in cytosine, thymine and guanine show important differences. It is hypothesized that these differences indicate differences in the orientation of these groups with respect to the surface
Deep Perceptual Mapping for Thermal to Visible Face Recognition
Cross modal face matching between the thermal and visible spectrum is a much
de- sired capability for night-time surveillance and security applications. Due
to a very large modality gap, thermal-to-visible face recognition is one of the
most challenging face matching problem. In this paper, we present an approach
to bridge this modality gap by a significant margin. Our approach captures the
highly non-linear relationship be- tween the two modalities by using a deep
neural network. Our model attempts to learn a non-linear mapping from visible
to thermal spectrum while preserving the identity in- formation. We show
substantive performance improvement on a difficult thermal-visible face
dataset. The presented approach improves the state-of-the-art by more than 10%
in terms of Rank-1 identification and bridge the drop in performance due to the
modality gap by more than 40%.Comment: BMVC 2015 (oral
Fourier transform infrared spectrometer for a single aerosol particle
A spectrometer is reported here for obtaining the infrared spectrum of a single aqueous aerosol particle by a Fourier transform technique. The particle is held in an electrodynamic balance and irradiated simultaneously by the infrared output from a Michelson interferometer and the visible light from a dye laser. The size of the particle is modulated by chopping the IR beam, and the resulting visible scattered light fluctuation is detected at 90° with a photomultiplier tube. The amplitude of the scattered light fluctuation is measured with a lock-in amplifier at each interferometer mirror position. The electronic circuitry for stepping the interferometer mirror is presented and discussed. Inverting the lock-in signal by a discrete fast Fourier transform routine (FFT) yields the particle absorption spectrum. The resulting spectrum for an (NH4)2SO4 droplet is presented
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