843 research outputs found
Nature-inspired Cuckoo Search Algorithm for Side Lobe Suppression in a Symmetric Linear Antenna Array
In this paper, we proposed a newly modified cuckoo search (MCS) algorithm integrated with the Roulette wheel selection operator and the inertia weight controlling the search ability towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The basic cuckoo search (CS) algorithm is primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Levy flight behavior of some birds and fruit flies. The CS metaheuristic approach is straightforward and capable of solving effectively general N-dimensional, linear and nonlinear optimization problems. The array geometry synthesis is first formulated as an optimization problem with the goal of SLL suppression and/or null prescribed placement in certain directions, and then solved by the newly MCS algorithm for the optimum element or isotropic radiator locations in the azimuth-plane or xy-plane. The study also focuses on the four internal parameters of MCS algorithm specifically on their implicit effects in the array synthesis. The optimal inter-element spacing solutions obtained by the MCS-optimizer are validated through comparisons with the standard CS-optimizer and the conventional array within the uniform and the Dolph-Chebyshev envelope patterns using MATLABTM. Finally, we also compared the fine-tuned MCS algorithm with two popular evolutionary algorithm (EA) techniques include particle swarm optimization (PSO) and genetic algorithms (GA)
Reactor Searches for Neutrino Magnetic Moment as a Probe of Extra Dimensions
We present calculations of the magnetic moment contribution to neutrino
electron scattering in large extra dimension brane-bulk models (LED) with three
bulk neutrinos. We discuss the cases with two and three large extra dimensions
of sizes . The calculations are done using reactor flux from Uranium,
as the neutrino source. We find that if the electron neutrino mass is
chosen to be in the range of one eV, the differential cross section for
scattering for low electron recoil energy can be of the same
order as the presently explored values in reactor experiments. Furthermore the
spectral shape for the LED models is different from the four dimensional case.
Future higher precision reactor experiments can therefore be used to provide
new constraints on a class of large extra dimension theories.Comment: 8 pages; 3 figure
Ghost Cosmology: Exact Solutions, Transitions Between Standard Cosmologies and Ghost Dark Energy/Matter Evolution
The recently proposed infrared modification of gravity through the
introduction of a ghost scalar field results in a number of interesting
cosmological and phenomenological implications. In this paper, we derive the
exact cosmological solutions for a number of scenarios where at late stages,
the ghost behaves like dark matter, or dark energy. The full solutions give
valuable information about the non-linear regime beyond the asymptotic first
order analysis presented in the literature. The generic feature is that these
ghost cosmologies give rise to smooth transitions between radiation dominated
phases (or more general power-law expansions) at early epochs and ghost dark
matter resp. ghost dark energy dominated late epochs. The current age of our
universe places us right at the non-linear transition phase. By studying the
evolution backwards in time, we find that the dominance of the ghost over
ordinary baryonic matter and radiative contributions persists back to the
earliest times such that the Friedmann-Robertson-Walker geometry is dictated to
a good approximation by the ghost alone. We also find that the Jeans
instability occurs in the ghost dark energy scenario at late times, while it is
absent in the ghost dark matter scenario.Comment: 31 pages, 9 figures; added references, clarified a few minor point
Do Individual Investors Drive Post-Earnings Announcement Drift? Direct Evidence from Personal Trades
This study examines whether individual investors are the source of post- earnings announcement drift (PEAD). We provide evidence on how individual investors trade in response to extreme quarterly earnings surprises and on the relation between individual investors' trades and subsequent abnormal returns. We find no evidence that either individuals or any sub-category of individuals in our sample cause PEAD. Individuals are significant net buyers after both negative and positive earnings surprises. There is no indication that trading by any of our investor sub-categories explains the concentration of drift at subsequent earnings announcement dates. While post-announcement individual net buying is a significant negative predictor of stock returns over the next three quarters, individual investor trading fails to subsume any of the power of extreme earnings surprises to predict future abnormal returns.post earnings-announcement drift, trading activity, individual investors, market efficiency
Cognitive network science: A review of research on cognition through the lens of network representations, processes, and dynamics
10.1155/2019/2108423Complexity2019210842
The influence of cultural similarity and individual factors on visitation
This paper examined how Chinese, German and American individualsâ perceptions of cultural similarity/difference influence intentions to travel to New Zealand, a novel long-haul destination. The relationship was examined along with a set of potentially influential individual difference variables, including international travel experience, uncertainty avoidance, novelty seeking and ethnocentrism. Cultural similarity was a common positive predictor of travel intentions toward New Zealand across all three countries. Respondentâs travel experience and novelty seeking were also important positive influences for this long-haul destination, at least for Americans and Germans. Respondentâs level of uncertainty avoidance was only
significant for Germany, where those with higher uncertainty were less likely to intend to visit New Zealand. Ethnocentrism was not a significant predictor in any country. These findings suggest that the perception of cultural similarity, which can be influenced by marketing campaigns, has a positive influence on travel intentions.
Tourism marketers should stress elements of cultural similarity in their campaigns, especially for those markets where there may be lower levels of knowledge about the destination
Minimal SUSY SO(10), b- unification and large neutrino mixings
We show that the assumption of type II seesaw mechanism for small neutrino
masses coupled with mass unification in a minimal SUSY SO(10) model
leads not only to a natural understanding of large atmospheric mixing angle
() among neutrinos, as recently pointed out, but also to large
solar angle () and a small as required
to fit observations. This is therefore a minimal, completely realistic grand
unified model for all low energy observations that naturally explains the
diverse mixing patterns between the quark and leptons without any additional
inputs such as extra global symmetries. The proposed long baseline neutrino
experiments will provide a crucial test of this model since it predicts
for the allowed range of parameters.Comment: 15 pages, latex, 3 figures, UMD-PP-03-03
Impact of the Fan Design and Rotational Direction on the Thermal Characteristics of Induction Motors
Functional Role and Affinity of Inorganic Cations in Stabilizing the Tetrameric Structure of the KcsA K+ Channel
Crystal structures of the tetrameric KcsA K+ channel reveal seven distinct binding sites for K+ ions within the central pore formed at the fourfold rotational symmetry axis. Coordination of an individual K+ ion by eight protein oxygen atoms within the selectivity filter suggests that ion-subunit bridging by cationâoxygen interactions contributes to structural stability of the tetramer. To test this hypothesis, we examined the effect of inorganic cations on the temperature dependence of the KcsA tetramer as monitored by SDS-PAGE. Inorganic cations known to permeate or strongly block K+ channels (K+, Rb+, Cs+, Tl+, NH4+, Ba2+, and Sr2+) confer tetramer stability at higher temperatures (T0.5 range = 87°C to >99°C) than impermeant cations and weak blockers (Li+, Na+, Tris+, choline+; T0.5 range = 59°C to 77°C). Titration of K+, Ba2+, and other stabilizing cations protects against rapid loss of KcsA tetramer observed in 100 mM choline Cl at 90°C. Tetramer protection titrations of K+, Rb+, Cs+, Tl+, and NH4+ at 85°C or 90°C exhibit apparent Hill coefficients (N) ranging from 1.7 to 3.3 and affinity constants (K0.5) ranging from 1.1 to 9.6 mM. Ba2+ and Sr2+ titrations exhibit apparent one-site behavior (N â
1) with K0.5 values of 210 nM and 11 ΌM, respectively. At 95°C in the presence of 5 mM K+, titration of Li+ or Na+ destabilizes the tetramer with K0.5 values of 57 mM and 109 mM, respectively. We conclude that specific binding interactions of inorganic cations with the selectivity filter are an important determinant of tetramer stability of KscA
Characterisation of the Cullin-3 mutation that causes a severe form of familial hypertension and hyperkalaemia
Deletion of exon 9 from Cullinâ3 (CUL3, residues 403â459: CUL3Î403â459) causes pseudohypoaldosteronism type IIE (PHA2E), a severe form of familial hyperkalaemia and hypertension (FHHt). CUL3 binds the RING protein RBX1 and various substrate adaptors to form CullinâRINGâubiquitinâligase complexes. Bound to KLHL3, CUL3âRBX1 ubiquitylates WNK kinases, promoting their ubiquitinâmediated proteasomal degradation. Since WNK kinases activate Na/Cl coâtransporters to promote salt retention, CUL3 regulates blood pressure. Mutations in both KLHL3 and WNK kinases cause PHA2 by disrupting CullinâRINGâligase formation. We report here that the PHA2E mutant, CUL3Î403â459, is severely compromised in its ability to ubiquitylate WNKs, possibly due to altered structural flexibility. Instead, CUL3Î403â459 autoâubiquitylates and loses interaction with two important Cullin regulators: the COP9âsignalosome and CAND1. A novel knockâin mouse model of CUL3WT/Î403â459 closely recapitulates the human PHA2E phenotype. These mice also show changes in the arterial pulse waveform, suggesting a vascular contribution to their hypertension not reported in previous FHHt models. These findings may explain the severity of the FHHt phenotype caused by CUL3 mutations compared to those reported in KLHL3 or WNK kinases
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