1,583 research outputs found
Large area radio frequency plasma for microelectronics processing
Includes bibliographical references (page 874).Radio-frequency (rf) inductively coupled planar plasma (ICP) provides a better way to generate spatially confined high density gas discharge plasmas for microelectronics processing. Commercial processing equipment using this technique is currently available, but is limited in size to 20 cm in diameter by problems with plasma uniformity and antenna dielectric window erosion. We have developed a new planar ICP antenna and dielectric window design that allows for larger dimensions (up to 50 cm in diameter) with good uniformity. The current art ICP antenna requires a thick quartz (or ceramic) plate vacuum window to separate the rf inductor and the plasma. The larger the antenna diameter the thicker the dielectric. The thick dielectric reduces inductive coupling efficiency. The large area coil and associated matching network can introduce plasma uniformity problems. Our device incorporates both the rf inductor and the dielectric window inside the vacuum chamber, allowing space for a thin layer of quartz or other dielectric material. Thus, the dielectric window design is only focused on materials for the given process chemistry to be placed between the coil and the excited plasma, rather than also including mechanical strength to hold a vacuum over a wide area. This thin dielectric layer with our newly designed planar coil coupler allows the plasma to be scaled to a 50 cm diameter while maintaining radial uniformity. In this article we report only plasma ashing results for a 20 cm planar ICP device that shows 2% nonuniformity across 15 cm wafers. The measured flux of atomic oxygen and atomic hydrogen generated by a larger planar ICP scale device is also presented
One-dimensional sigma-models with N=5,6,7,8 off-shell supersymmetries
We computed the actions for the 1D N=5 sigma-models with respect to the two
inequivalent (2,8,6) multiplets. 4 supersymmetry generators are manifest, while
the constraint originated by imposing the 5-th supersymmetry automatically
induces a full N=8 off-shell invariance. The resulting action coincides in the
two cases and corresponds to a conformally flat 2D target satisfying a special
geometry of rigid type. To obtain these results we developed a computational
method (for Maple 11) which does not require the notion of superfields and is
instead based on the nowadays available list of the inequivalent
representations of the 1D N-extended supersymmetry. Its application to
systematically analyze the sigma-models off-shell invariant actions for the
remaining N=5,6,7,8 (k,8,8-k) multiplets, as well as for the N>8
representations,only requires more cumbersome computations.Comment: 10 pages; one reference adde
Exact Histogram Specification Optimized for Structural Similarity
An exact histogram specification (EHS) method modifies its input image to
have a specified histogram. Applications of EHS include image (contrast)
enhancement (e.g., by histogram equalization) and histogram watermarking.
Performing EHS on an image, however, reduces its visual quality. Starting from
the output of a generic EHS method, we maximize the structural similarity index
(SSIM) between the original image (before EHS) and the result of EHS
iteratively. Essential in this process is the computationally simple and
accurate formula we derive for SSIM gradient. As it is based on gradient
ascent, the proposed EHS always converges. Experimental results confirm that
while obtaining the histogram exactly as specified, the proposed method
invariably outperforms the existing methods in terms of visual quality of the
result. The computational complexity of the proposed method is shown to be of
the same order as that of the existing methods.
Index terms: histogram modification, histogram equalization, optimization for
perceptual visual quality, structural similarity gradient ascent, histogram
watermarking, contrast enhancement
Addressing Rice Waste in University Cafeterias Using Material Flow Analysis and System Dynamics Modeling
Food waste has emerged as one of the focus areas in sustainability research. At the Ateneo de Manila University, previous studies have found that food waste is composed mainly of rice. This study, therefore, analyzed cafeteria rice systems in the university through a material flow analysis (MFA) to identify key factors for formulating effective rice waste reduction techniques and then applied the results toward developing system dynamics (SD) models as tools for decision-making. The MFA found that the total mass of produced known rice waste was 49.48 kg/d. The largest sources of rice wastes were the upstream processes of the cafeteria rice system involving the cooking and serving of rice. The SD model developed for one cafeteria found that the service stage was the largest source of rice waste. The main factor influencing service waste generation was the surplus of cooked rice. A scenario was simulated in which the amount of rice used in additional batches cooked was minimized, yielding a substantial decrease in the mass of service waste and lost revenue. Not only does this research provide baseline information that enables the university to enhance sustainable consumption and food waste minimization efforts, but it also contributes to the data pool for rice wastage in the Philippine and Southeast Asian contexts. Furthermore, results indicate a need to re-strategize rice waste campaigns that focus on consumption when much can be done in the preparation and service stages. Collaborating with cafeteria management to improve efficiency in the kitchen is key in addressing the overall rice waste problem. Downstream, consumer-focused interventions targeting changes in attitudes and behaviors must be complemented by upstream changes in operations and management approaches to support both a structural and cultural transformation for sustainability
One-dimensional structures behind twisted and untwisted superYang-Mills theory
We give a one-dimensional interpretation of the four-dimensional twisted N=1
superYang-Mills theory on a Kaehler manifold by performing an appropriate
dimensional reduction. We prove the existence of a 6-generator superalgebra,
which does not possess any invariant Lagrangian but contains two different
subalgebras that determine the twisted and untwisted formulations of the N=1
superYang-Mills theory.Comment: 12 pages. Final version to appear in Lett. Math. Phys. with improved
notation and misprints correcte
Supersymmetric Extension of Hopf Maps: N=4 sigma-models and the S^3 -> S^2 Fibration
We discuss four off-shell N=4 D=1 supersymmetry transformations, their
associated one-dimensional sigma-models and their mutual relations. They are
given by I) the (4,4)_{lin} linear supermultiplet (supersymmetric extension of
R^4), II) the (3,4,1)_{lin} linear supermultiplet (supersymmetric extension of
R^3), III) the (3,4,1)_{nl} non-linear supermultiplet living on S^3 and IV) the
(2,4,2)_{nl} non-linear supermultiplet living on S^2. The I -> II map is the
supersymmetric extension of the R^4 -> R^3 bilinear map, while the II -> IV map
is the supersymmetric extension of the S^3 -> S^2 first Hopf fibration. The
restrictions on the S^3, S^2 spheres are expressed in terms of the
stereographic projections. The non-linear supermultiplets, whose
supertransformations are local differential polynomials, are not equivalent to
the linear supermultiplets with the same field content. The sigma-models are
determined in terms of an unconstrained prepotential of the target coordinates.
The Uniformization Problem requires solving an inverse problem for the
prepotential. The basic features of the supersymmetric extension of the second
and third Hopf maps are briefly sketched. Finally, the Schur's lemma (i.e. the
real, complex or quaternionic property) is extended to all minimal linear
supermultiplets up to N<=8.Comment: 24 page
Second Hopf map and supersymmetric mechanics with Yang monopole
We propose to use the second Hopf map for the reduction (via SU(2) group
action) of the eight-dimensional N=8 supersymmetric mechanics to
five-dimensional supersymmetric systems specified by the presence of an SU(2)
Yang monopole. For our purpose we develop the relevant Lagrangian reduction
procedure. The reduced system is characterized by its invariance under the N=5
or N=4 supersymmetry generators (with or without an additional conserved BRST
charge operator) which commute with the su(2) generators.Comment: Final version. To appear in Phys. Rev.
The light-cone gauge and the calculation of the two-loop splitting functions
We present calculations of next-to-leading order QCD splitting functions,
employing the light-cone gauge method of Curci, Furmanski, and Petronzio (CFP).
In contrast to the `principal-value' prescription used in the original CFP
paper for dealing with the poles of the light-cone gauge gluon propagator, we
adopt the Mandelstam-Leibbrandt prescription which is known to have a solid
field-theoretical foundation. We find that indeed the calculation using this
prescription is conceptionally clear and avoids the somewhat dubious
manipulations of the spurious poles required when the principal-value method is
applied. We reproduce the well-known results for the flavour non-singlet
splitting function and the N_C^2 part of the gluon-to-gluon singlet splitting
function, which are the most complicated ones, and which provide an exhaustive
test of the ML prescription. We also discuss in some detail the x=1 endpoint
contributions to the splitting functions.Comment: 41 Pages, LaTeX, 8 figures and tables as eps file
3-quasi-Sasakian manifolds
In the present paper we carry on a systematic study of 3-quasi-Sasakian
manifolds. In particular we prove that the three Reeb vector fields generate an
involutive distribution determining a canonical totally geodesic and Riemannian
foliation. Locally, the leaves of this foliation turn out to be Lie groups:
either the orthogonal group or an abelian one. We show that 3-quasi-Sasakian
manifolds have a well-defined rank, obtaining a rank-based classification.
Furthermore, we prove a splitting theorem for these manifolds assuming the
integrability of one of the almost product structures. Finally, we show that
the vertical distribution is a minimum of the corrected energy.Comment: 17 pages, minor modifications, references update
Frecuencia de piometra en perras pacientes de la Clínica de Animales Menores de la Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos durante el periodo 2009-2013
Clinical records of bitches older than six months that were treated at the Small Animals Clinic of the Faculty of Veterinary Medicine of the Universidad Nacional Mayor de San Marcos during the period 2009-2013 were revised to obtain statistical information about the frequency of pyometra and its relationship with age, breed, size and season of the year. Out of 4715 records of bitches, 207 were diagnosed with pyometra, representing an incidence of 4.4 ± 0.6%. A statistical association was found between pyometra and breed, but not with the size of the animal or the season of the year.Se revisaron las fichas clínicas de perras mayores de seis meses que fueron atendidas en la Clínica de Animales Menores de la Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos durante el periodo 2009-2013, con el fin de obtener información estadística acerca de la frecuencia de piometra y su relación con la edad, raza, tamaño y estación del año. De los 4715 registros de perras, 207 fueron diagnosticados con piometra, representando un 4.4 ± 0.6% de incidencia. Se halló asociación estadística entre la raza y la piometra, más no así con el tamaño del animal ni la estación del año
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