634 research outputs found
Examining The Role Of Executive Functions In Focal Processing Of Event-Based Prospective Memory
Prospective Memory (PM) refers to remembering an intention to be acted upon in the future. Such a memory may be triggered by an event (i.e., Event-based PM) where a specific cue reminds one of the previously encoded intention. PM can be assessed in a lab-setting by having subjects learn a baseline task, subsequently receiving a PM instruction, completing a distractor task, and then going through a test phase where the PM task (i.e., responding to PM cues) is embedded within the ongoing task. The multiprocess view (McDaniel & Einstein, 2000) posits that PM can be retrieved primarily using two different strategies: one can strategically monitor for the PM cue to keep the intention in mind or spontaneously retrieve the intention by coming across the cue.
The multiprocess view suggests that monitoring or spontaneous retrieval strategies are chosen based on whether one’s current task is focal or non-focal to the nature of the PM task. When processing of the ongoing task stimuli and PM stimuli overlap (i.e., focal), spontaneous retrieval of the encoded intention is thought to occur more often. On the other hand, when processing of the PM stimuli is peripheral (i.e., non-focal) to the ongoing task, one may have to consistently monitor for the PM cue for successful task performance. Manipulation of PM task focality has shown a PM
performance advantage in focal conditions (Einstein & McDaniel, 2005), confirming the focality effect posited by the Multiprocess view.
Past studies (e.g., Schnitzspahn, Stahl, Zeintl, Kaller, & Kliegel, 2013) have suggested that some aspects of executive function (EF) are involved in non-focal PM performance. However, according to the multiprocess view, spontaneous retrieval of the PM cue can occur when the ongoing task is focal to the PM task. Because subjects may not need to appropriate as many cognitive resources toward the PM task, EF might be unrelated to PM performance in focal tasks. The current study tested this idea by examining a sample of college-aged subjects on two event-based PM (category and syllable judgments) and two EF (inhibition and task-switching) tasks. Subjects were assigned to focal or non-focal conditions for the PM tasks. The prediction of a focal condition advantage was found for PM performance measures, particularly in the syllables task. No relationships were found between PM performance and EF measures for the focal condition, as predicted. However, most of the predicted relationships between PM performance and EF measures for the non-focal condition were not confirmed, with the exception of a correlation between inhibition and PM performance measures. Further, EF measures could not account for performance differences across focality conditions. These findings were evaluated in terms of current theories of PM and implications of the current study were addressed
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An L∞ regularisation strategy to the inverse source identification problem for elliptic equations
In this paper we utilise new methods of Calculus of Variations in L ∞ to provide a regularisation strategy to the ill-posed inverse problem of identifying the source of a non-homogeneous linear elliptic equation, satisfying Dirichlet data on a domain. One of the advantages over the classical Tykhonov regularisation in L 2 is that the approximated solution of the PDE is uniformly close to the noisy measurements taken on a compact subset of the domain
Monte Carlo study of Si(111) homoepitaxy
An attempt is made to simulate the homoepitaxial growth of a Si(111) surface
by the kinetic Monte Carlo method in which the standard Solid-on-Solid model
and the planar model of the (7x7) surface reconstruction are used in
combination.
By taking account of surface reconstructions as well as atomic deposition and
migrations, it is shown that the effect of a coorparative stacking
transformation is necessary for a layer growth.Comment: 4 pages, 5 figures. For Fig.1 of this article, please see Fig.2 of
Phys.Rev. B56, 3583 (1997). To appear in Phys.Rev.B. (June 1998
Double-Exchange Ferromagnetism and Orbital-Fluctuation-Induced Superconductivity in Cubic Uranium Compounds
A double-exchange mechanism for the emergence of ferromagnetism in cubic
uranium compounds is proposed on the basis of a - coupling scheme. The
idea is {\it orbital-dependent duality} of electrons concerning itinerant
and localized states in the cubic structure. Since
orbital degree of freedom is still active in the ferromagnetic phase,
orbital-related quantum critical phenomenon is expected to appear. In fact,
odd-parity p-wave pairing compatible with ferromagnetism is found in the
vicinity of an orbital ordered phase. Furthermore, even-parity d-wave pairing
with significant odd-frequency components is obtained. A possibility to observe
such exotic superconductivity in manganites is also discussed briefly.Comment: 4 pages, 4 figures. To appear in J. Phys. Soc. Jp
A novel missense mutation of SLC7A9 frequent in Japanese cystinuria cases affecting the C-terminus of the transporter
Cystinuria is caused by the inherited defect of apical membrane transport systems for cystine and dibasic amino acids in renal proximal tubules. Mutations in either SLC7A9 or SLC3A1 gene result in cystinuria. The mutations of SLC7A9 gene have been identified mainly from Italian, Libyan Jewish, North American, and Spanish patients. In the present study, we have analyzed cystinuria cases from oriental population (mostly Japanese). Mutation analyses of SLC7A9 and SLC3A1 genes were performed on 41 cystinuria patients. The uptake of 14C-labeled cystine in COS-7 cells was measured to determine the functional properties of mutants. The protein expression and localization were examined by Western blot and confocal laser-scanning microscopy. Among 41 patients analyzed, 35 were found to possess mutations in SLC7A9. The most frequent one was a novel missense mutation P482L that affects a residue near the C-terminus end of the protein and causes severe loss of function. In MDCK II and HEK293 cells, we found that P482L protein was expressed and sorted to the plasma membrane as well as wild type. The alteration of Pro482 with amino acids with bulky side chains reduced the transport function of b0,+AT/BAT1. Interestingly, the mutations of SLC7A9 for Japanese cystinuria patients are different from those reported for European and American population. The results of the present study contribute toward understanding the distribution and frequency of cystinuria-related mutations of SLC7A9
Involvement of Mhc Loci in immune responses that are not Ir-gene-controlled
Twenty-nine randomly chosen, soluble antigens, many of them highly complex, were used to immunize mice of two strains, C3H and B10.RIII. Lymphnode cells from the immunized mice were restimulated in vitro with the priming antigens and the proliferative response of the cells was determined. Both strains were responders to 28 of 29 antigens. Eight antigens were then used to immunize 11 congenic strains carrying different H-2 haplotypes, and the T-cell proliferative responses of these strains were determined. Again, all the strains responded to seven of the eight antigens. These experiments were then repeated, but this time -antibodies specific for the A (AA) or E (EE) molecules were added to the culture to block the in vitro responsiveness. In all but one of the responses, inhibition with both A-specific and E-specific antibodies was observed. The response to one antigen (Blastoinyces) was exceptional in that some strains were nonresponders to this antigen. Furthermore, the response in the responder strains was blocked with A-specific, but not with E-specific, antibodies. The study demonstrates that responses to antigens not controlled by Irr genes nevertheless require participation of class II Mhc molecules. In contrast to Ir gene-controlled responses involving either the A- or the E-molecule controlling loci (but never both), the responses not Ir-controlled involve participation of both A- and E-controlling loci. The lack of Ir-gene control is probably the result of complexity of the responses to multiple determinants. There is thus no principal difference between responses controlled and those not controlled by Ir genes: both types involve the recognition of the antigen, in the context of Mhc molecules
On the Puzzle of Odd-Frequency Superconductivity
Since the first theoretical proposal by Berezinskii, an odd-frequency
superconductivity has encountered the fundamental problems on its thermodynamic
stability and rigidity of a homogenous state accompanied by unphysical Meissner
effect. Recently, Solenov {\it et al}. [Phys. Rev. B {\bf 79} (2009) 132502.]
have asserted that the path-integral formulation gets rid of the difficulties
leading to a stable homogenous phase with an ordinary Meissner effect. Here, we
show that it is crucial to choose the appropriate saddle-point solution that
minimizes the effective free energy, which was assumed {\it implicitly} in the
work by Solenov and co-workers. We exhibit the path-integral framework for the
odd-frequency superconductivity with general type of pairings, including an
argument on the retarded functions via the analytic continuation to the real
axis.Comment: 6 pages, in JPSJ forma
Possible Odd-Frequency Superconductivity in Strong-Coupling Electron-Phonon Systems
A possibility of the odd-frequency pairing in the strong-coupling
electron-phonon systems is discussed. Using the Holstein-Hubbard model, we
demonstrate that the anomalously soft Einstein mode with the frequency
( is the order of the renormalized
bandwidth) mediates the s-wave odd-frequency triplet pairing against the
ordinary even-frequency singlet pairing. It is necessary for the emergence of
the odd-frequency pairing that the pairing interaction is strongly retarded as
well as the strong coupling, since the pairing interaction for the
odd-frequency pairing is effective only in the diagonal scattering channel,
with
. Namely, the odd-frequency
superconductivity is realized in the opposite limit of the original BCS theory.
The Ginzburg-Landau analysis in the strong-coupling region shows that the
specific-heat discontinuity and the slope of the temperature dependence of the
superfluid density can be quite small as compared with the BCS values,
depending on the ratio of the transition temperature and .Comment: 6 pages, 7 figures, submitted to J. Phys. Soc. Jp
On the Meissner Effect of the Odd-Frequency Superconductivity with Critical Spin Fluctuations: Possibility of Zero Field FFLO pairing
We investigate the influence of critical spin fluctuations on electromagnetic
responses in the odd-frequency superconductivity. It is shown that the Meissner
kernel of the odd-frequency superconductivity is strongly reduced by the
critical spin fluctuation or the massless spin wave mode in the
antiferromagnetic phase. These results imply that the superfluid density is
reduced, and the London penetration depth is lengthened for the odd-frequency
pairing. It is also shown that the zero field Flude-Ferrell-Larkin-Ovchinnikov
pairing is spontaneously realized both for even- and odd-frequency in the case
of sufficiently strong coupling with low lying spin-modes.Comment: 10 pages, 7 figure
Symmetry and Topology in Superconductors - Odd-frequency pairing and edge states -
Superconductivity is a phenomenon where the macroscopic quantum coherence
appears due to the pairing of electrons. This offers a fascinating arena to
study the physics of broken gauge symmetry. However, the important symmetries
in superconductors are not only the gauge invariance. Especially, the symmetry
properties of the pairing, i.e., the parity and spin-singlet/spin-triplet,
determine the physical properties of the superconducting state. Recently it has
been recognized that there is the important third symmetry of the pair
amplitude, i.e., even or odd parity with respect to the frequency. The
conventional uniform superconducting states correspond to the even-frequency
pairing, but the recent finding is that the odd-frequency pair amplitude arises
in the spatially non-uniform situation quite ubiquitously. Especially, this is
the case in the Andreev bound state (ABS) appearing at the surface/interface of
the sample. The other important recent development is on the nontrivial
topological aspects of superconductors. As the band insulators are classified
by topological indices into (i) conventional insulator, (ii) quantum Hall
insulator, and (iii) topological insulator, also are the gapped
superconductors. The influence of the nontrivial topology of the bulk states
appears as the edge or surface of the sample. In the superconductors, this
leads to the formation of zero energy ABS (ZEABS). Therefore, the ABSs of the
superconductors are the place where the symmetry and topology meet each other
which offer the stage of rich physics. In this review, we discuss the physics
of ABS from the viewpoint of the odd-frequency pairing, the topological
bulk-edge correspondence, and the interplay of these two issues. It is
described how the symmetry of the pairing and topological indices determines
the absence/presence of the ZEABS, its energy dispersion, and properties as the
Majorana fermions.Comment: 91 pages, 38 figures, Review article, references adde
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