21,910 research outputs found
Improved source of infrared radiation for spectroscopy
Radiation from a crimped V-groove in the electrically heated metallic element of a high-resolution infrared spectrometer is more intense than that from plane areas adjacent to the element. Radiation from the vee and the flat was compared by alternately focusing on the entrance slit of a spectrograph
The eigenspectra of Indian musical drums
In a family of drums used in the Indian subcontinent, the circular drum head
is made of material of non-uniform density. Remarkably, and in contrast to a
circular membrane of uniform density, the low eigenmodes of the non-uniform
membrane are harmonic. In this work we model the drum head by a non-uniform
membrane whose density varies smoothly between two prescribed values. Using a
Fourier-Chebyshev spectral collocation method we obtain the eigenmodes and
eigenvalues of the drum head. For a suitable choice of parameters, which we
find by optimising a cost function, the eigenspectra obtained from our model
are in excellent agreement with experimental values. Our model and the
numerical method should find application in numerical sound synthesis
Unsupervised decoding of long-term, naturalistic human neural recordings with automated video and audio annotations
Fully automated decoding of human activities and intentions from direct
neural recordings is a tantalizing challenge in brain-computer interfacing.
Most ongoing efforts have focused on training decoders on specific, stereotyped
tasks in laboratory settings. Implementing brain-computer interfaces (BCIs) in
natural settings requires adaptive strategies and scalable algorithms that
require minimal supervision. Here we propose an unsupervised approach to
decoding neural states from human brain recordings acquired in a naturalistic
context. We demonstrate our approach on continuous long-term
electrocorticographic (ECoG) data recorded over many days from the brain
surface of subjects in a hospital room, with simultaneous audio and video
recordings. We first discovered clusters in high-dimensional ECoG recordings
and then annotated coherent clusters using speech and movement labels extracted
automatically from audio and video recordings. To our knowledge, this
represents the first time techniques from computer vision and speech processing
have been used for natural ECoG decoding. Our results show that our
unsupervised approach can discover distinct behaviors from ECoG data, including
moving, speaking and resting. We verify the accuracy of our approach by
comparing to manual annotations. Projecting the discovered cluster centers back
onto the brain, this technique opens the door to automated functional brain
mapping in natural settings
Solitary Dust--Acoustic Waves in a Plasma with Two-Temperature Ions and Distributed Grain Size
The propagation of weakly nonlinear dust--acoustic waves in a dusty plasma
containing two ion species with different temperatures is explored. The
nonlinear equations describing both the quadratic and cubic plasma
nonlinearities are derived. It is shown that the properties of dust--acoustic
waves depend substantially on the grain size distribution. In particular, for
solitary dust--acoustic waves with a positive potential to exist in a plasma
with distributed grain size, it is necessary that the difference between the
temperatures of two ion species be large that that in the case of unusized
grains.Comment: 16 pages, 6 figure
Calcium Silicide - Methods of production and their technological consideration
Three industrial methods of production of calcium silicide have been discussed with their merits and demerits along with technological considerations. Calcium silicide was produced at NML in 500 KVA submerged arc furnace using partial charging method. Based on the results
and observations of the smelting trials carried out a model has been proposed to explain the mechanism of form-ation of calcium silicide. Inoculation trials with calcium silicide produced at NML compares favourably with those obtained from abroad
Phonon dispersion and electron-phonon interaction in peanut-shaped fullerene polymers
We reveal that the periodic radius modulation peculiar to one-dimensional
(1D) peanut-shaped fullerene (C) polymers exerts a strong influence on
their low-frequency phonon states and their interactions with mobile electrons.
The continuum approximation is employed to show the zone-folding of phonon
dispersion curves, which leads to fast relaxation of a radial breathing mode in
the 1D C polymers. We also formulate the electron-phonon interaction
along the deformation potential theory, demonstrating that only a few set of
electron and phonon modes yields a significant magnitude of the interaction
relevant to the low-temperature physics of the system. The latter finding gives
an important implication for the possible Peierls instability of the C
polymers suggested in the earlier experiment.Comment: 9 pages, 8 figure
Diversity and Distribution of Pteridophytic flora of Punyagiri hill, Vizianagaram District, Andhra Pradesh, India
The present paper deals with the diversity and distribution of Pteridophytic flora in Punyagiri hill. It is located 180 06’ 70",180 06’ 68",latitudes and 830 06’ 72",830 06’ 40" longitudes , 55 km away from Visakhapatnam. Quadrate method was adopted to calculate the IVI. Sampling was carried out with 0.5x0.5m2 quadrate; fifteen quadrate samples were taken in three seasons. A total no of 13 species belonging to 10 genera and 9 families were recorded. Maximum relative density was reported for Selaginella involvense (10.6) and Pteris vittata (8.4). Minimum relative density and relative frequency were reported in the species Nephrolepis cordifolia(5.5) and Pteris pellucida (6.3). The maximum IVI was reported in Selaginella involvens (30.2) fallowed by Pteris vittata (26.2), Adiantum lunulatum(25.4), Pleopeltis pallida (24.5) and minimum in Nephrolepis cordifolia (18.6). It is concluded that the population of Pteridophytes in this region is heterogeneous
Acceptability with general orderings
We present a new approach to termination analysis of logic programs. The
essence of the approach is that we make use of general orderings (instead of
level mappings), like it is done in transformational approaches to logic
program termination analysis, but we apply these orderings directly to the
logic program and not to the term-rewrite system obtained through some
transformation. We define some variants of acceptability, based on general
orderings, and show how they are equivalent to LD-termination. We develop a
demand driven, constraint-based approach to verify these
acceptability-variants.
The advantage of the approach over standard acceptability is that in some
cases, where complex level mappings are needed, fairly simple orderings may be
easily generated. The advantage over transformational approaches is that it
avoids the transformation step all together.
{\bf Keywords:} termination analysis, acceptability, orderings.Comment: To appear in "Computational Logic: From Logic Programming into the
Future
Genetic analysis of some exotic x Indian crosses in sorghum. VI. Dynamics of character association under selection
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