7,685 research outputs found
A dynamic neural field model of temporal order judgments
Temporal ordering of events is biased, or influenced, by perceptual organization—figure–ground organization—and by spatial attention. For example, within a region assigned figural status or at an attended location, onset events are processed earlier (Lester, Hecht, & Vecera, 2009; Shore, Spence, & Klein, 2001), and offset events are processed for longer durations (Hecht & Vecera, 2011; Rolke, Ulrich, & Bausenhart, 2006). Here, we present an extension of a dynamic field model of change detection (Johnson, Spencer, Luck, & Schöner, 2009; Johnson, Spencer, & Schöner, 2009) that accounts for both the onset and offset performance for figural and attended regions. The model posits that neural populations processing the figure are more active, resulting in a peak of activation that quickly builds toward a detection threshold when the onset of a target is presented. This same enhanced activation for some neural populations is maintained when a present target is removed, creating delays in the perception of the target’s offset. We discuss the broader implications of this model, including insights regarding how neural activation can be generated in response to the disappearance of information. (PsycINFO Database Record (c) 2015 APA, all rights reserved
Post-Quantum Cryptography: S
Currently there is an active Post-Quantum Cryptography (PQC) solutions search, which attempts to find cryptographic protocols resistant to attacks by means of for instance Shor's polynomial time algorithm for numerical field problems like integer factorization (IFP) or the discrete logarithm (DLP). The use of non-commutative or non-associative structures are, among others, valid choices for these kinds of protocols. In our case, we focus on a permutation subgroup of high order and belonging to the symmetric group S381. Using adequate one-way functions (OWF), we derived a Diffie-Hellman key exchange and an ElGamal ciphering procedure that only relies on combinatorial operations. Both OWF pose hard search problems which are assumed as not belonging to BQP time-complexity class. Obvious advantages of present protocols are their conceptual simplicity, fast throughput implementations, high cryptanalytic security and no need for arithmetic operations and therefore extended precision libraries. Such features make them suitable for low performance and low power consumption platforms like smart cards, USB-keys and cellphones
Light Transmission Through Metallic-Mean Quasiperiodic Stacks with Oblique Incidence
The propagation of s- and p-polarized light through quasiperiodic
multilayers, consisting of layers with different refractive indices, is studied
by the transfer matrix method. In particular, we focus on the transmission
coefficient of the systems in dependency on the incidence angle and on the
ratio of the refractive indices. We obtain additional bands with almost
complete transmission in the quasiperiodic systems at frequencies in the range
of the photonic band gap of a system with a periodic alignment of the two
materials for both types of light polarization. With increasing incidence angle
these bands bend towards higher frequencies, where the curvature of the
transmission bands in the quasiperiodic stack depends on the metallic mean of
the construction rule. Additionally, in the quasiperiodic systems for
p-polarized light the bands show almost complete transmission near the
Brewster's angle in contrast to the results for s-polarized light. Further, we
present results for the influence of the refractive indices at the midgap
frequency of the periodic stack, where the quasiperiodicity was found to be
most effective.Comment: 10 pages, 7 figure
The Power of the Subversive Female in Hawthorne’s The Scarlet Letter and Blithedale Romance
Nathaniel Hawthorne is an author who has caused much intrigue, especially among feminist critics, some of whom deem him to be misogynistic and wholly supportive of the patriarchy in his texts. Evidence for this has been cited in his choice of the demure and quiet Sophia as his wife, although it is known she was amongst many close women in Hawthorne’s life, most of whom were more outspoken female contemporaries like Elizabeth Peabody and Margaret Fuller. Additionally, the assertion that Hawthorne’s writing contains misogynistic undertones is oftentimes supported by the plight of his female characters, who often suffer from painful heartbreak and unendurable social struggles at the hands of a more powerful and dominating patriarchal structure.
However, upon analysis of his personal relationships with the aforementioned feminist icons of his day, along with examination of Hester Prynne, of The Scarlet Letter, and Zenobia, of The Blithedale Romance, Hawthorne ultimately emerges as a pro-female writer who is not criticizing strong women, as some might assume from a surface reading of his work, but championing their cause, while exposing and critiquing the cruel patriarchs who stand as a roadblock to their success.
This thesis will argue that Hawthorne was a writer who used his knowledge of both feminism and the patriarchy to take a stand against the oppression ot strong women, and that this stance is primarily shown in the characters of Hester and Zenobia, who, while faced with patriarchal challenges on both personal and communal levels, both triumph in the end. The victories of these women are achieved through their strength, independence, and courage to wield truly progressive outlooks and participate in subsequently progressive behaviors as a means toward reformation. As stated by Nina Baym, the author who created these feminine paragons was undeniably pro-female
Pairing and Isospin Symmetry in Proton-Rich Nuclei
Unlike their lighter counterparts, most odd-odd N=Z nuclei with mass A > 40
40 have ground states with isospin T=1, suggesting an increased role for the
isovector pairing interaction. A simple SO(5) seniority-like model of this
interaction reveals a striking and heretofore unnoticed interplay between
like-particle and neutron-proton isovector pairing near N=Z that is reflected
in the number of each kind of pair as a function of A and T. Large scale
shell-model calculations exhibit the same trends, despite the simultaneous
presence of isoscalar pairs, deformation, and other correlations.Comment: 8 pages + 2 postscript figures, in RevTeX. Discussion of isospin
projection in HFB added. This version to appear in Phys. Lett.
Representation Theory Approach to the Polynomial Solutions of q - Difference Equations : U_q(sl(3)) and Beyond,
A new approach to the theory of polynomial solutions of q - difference
equations is proposed. The approach is based on the representation theory of
simple Lie algebras and their q - deformations and is presented here for
U_q(sl(n)). First a q - difference realization of U_q(sl(n)) in terms of
n(n-1)/2 commuting variables and depending on n-1 complex representation
parameters r_i, is constructed. From this realization lowest weight modules
(LWM) are obtained which are studied in detail for the case n=3 (the well known
n=2 case is also recovered). All reducible LWM are found and the polynomial
bases of their invariant irreducible subrepresentations are explicitly given.
This also gives a classification of the quasi-exactly solvable operators in the
present setting. The invariant subspaces are obtained as solutions of certain
invariant q - difference equations, i.e., these are kernels of invariant q -
difference operators, which are also explicitly given. Such operators were not
used until now in the theory of polynomial solutions. Finally the states in all
subrepresentations are depicted graphically via the so called Newton diagrams.Comment: uuencoded Z-compressed .tar file containing two ps files
The Gaussian formula and spherical aberration of the static and moving curved mirrors from Fermat's principle
The Gaussian formula and spherical aberrations of the static and relativistic
curved mirrors are analyzed using the optical path length (OPL) and Fermat's
principle. The geometrical figures generated by the rotation of conic sections
about their symmetry axes are considered for the shapes of the mirrors. By
comparing the results in static and relativistic cases, it is shown that the
focal lengths and the spherical aberration relations of the relativistic
mirrors obey the Lorentz contraction. Further analysis of the spherical
aberrations for both static and relativistic cases have resulted in the
information about the limits for the paraxial approximation, as well as for the
minimum speed of the systems to reduce the spherical aberrations.Comment: 15 pages, 7 figures, uses iopart. Major revisions on the physical
interpretations of the results. Accepted for publication in J. Op
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Solid Freeform Fabrication of Functional Silicon Nitride Ceramics by Laminated Object Manufacturing 1
The processing of silicon nitride (Si3N4) structural ceramics by Laminated Object
Manufacturing (LOM) using ceramic tape preforms was investigated. The key processing stages
involved green shape formation (which used the LOM process), followed by the burnout of all
organics, and final densification by pressureless sintering. Two material systems were
considered. These were a) monolithic Si3N4 and b) a preceramic polymer infiltrated Si3N4. The
raw materials for the process were tape preforms of Si3N4, which were fabricated by standard
tape casting techniques.
Mechanical property data obtained for the LOM processed Si3N4 showed high strength and
fracture toughness values. The room temperature and high temperature (1260 o
C) flexural
strengths were in the range of 700-900 MPa and 360-400 MPa, respectively. The fracture
toughness averaged from 5.5-7.5 MPa.m1/2. These strength and fracture toughness values are
comparable to those reported for conventionally prepared Si3N4 ceramics. Thus, this research
demonstrated that the LOM technique is a viable method for preparing functional Si3N4 ceramics
with good physical and mechanical properties.Mechanical Engineerin
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