Complex-valued Time Series Modeling for Improved Activation Detection in fMRI Studies

A complex-valued data-based model with th order autoregressive errors and general real/imaginary error covariance structure is proposed as an alternative to the commonly used magnitude-only data-based autoregressive model for fMRI time series. Likelihood-ratio-test-based activation statistics are derived for both models and compared for experimental and simulated data. For a dataset from a right-hand finger-tapping experiment, the activation map obtained using complex-valued modeling more clearly identifies the primary activation region (left functional central sulcus) than the magnitude-only model. Such improved accuracy in mapping the left functional central sulcus has important implications in neurosurgical planning for tumor and epilepsy patients. Additionally, we develop magnitude and phase detrending procedures for complex-valued time series and examine the effect of spatial smoothing. These methods improve the power of complex-valued data-based activation statistics. Our results advocate for the use of the complex-valued data and the modeling of its dependence structures as a more efficient and reliable tool in fMRI experiments over the current practice of using only magnitude-valued datasets

Particularities of the Communication Activities within the Modern Enterprise with a Study Case at SC DEDEMAN SRL

Inside an organization, communication has an important role. Communication should be oriented both towards the internal life of the organization and towards the external activity. The communication devices of the company serve to disseminate some major information about the products and services offered to the clients and they also serve to find out how the business environment reacts. Such a double communication system assures a permanent dialogue with the external environment, the market, supplying the firm with all the necessary elements for developing an efficient activity.Communication, Marketing communication, Communication policy, Promotional activity

Single transverse-spin asymmetries in forward pion production at high energy: incorporating small-x effects in the target

We consider single-inclusive forward pion production in high-energy proton-proton collisions at RHIC energies. A good baseline description of the transverse momentum distributions at high rapidity is obtained within Mueller's dipole formalism with an anomalous dimension incorporating an ``extended geometric scaling'' window between the saturation and DGLAP regimes. We then formulate pion production for transversely polarized projectiles within the same approach. We assume that an azimuthal, spin-dependent asymmetry arises from the so-called Sivers effect and investigate the single transverse-spin asymmetry A_N at 200 GeV and 500 GeV center-of-mass energy. A simple parameterization of the Sivers functions from the literature compares reasonably well with the high-energy STAR data if the overall normalization is scaled up by at least a factor of two. The STAR data might therefore indicate that the Sivers effect is significantly stronger than thought so far. We also analyze higher-twist contributions to A_N and find that they largely cancel.Comment: 15 pages, 7 figure

Parafermions in a Kagome lattice of qubits for topological quantum computation

Engineering complex non-Abelian anyon models with simple physical systems is crucial for topological quantum computation. Unfortunately, the simplest systems are typically restricted to Majorana zero modes (Ising anyons). Here we go beyond this barrier, showing that the $\mathbb{Z}_4$ parafermion model of non-Abelian anyons can be realized on a qubit lattice. Our system additionally contains the Abelian $D(\mathbb{Z}_4)$ anyons as low-energetic excitations. We show that braiding of these parafermions with each other and with the $D(\mathbb{Z}_4)$ anyons allows the entire $d=4$ Clifford group to be generated. The error correction problem for our model is also studied in detail, guaranteeing fault-tolerance of the topological operations. Crucially, since the non-Abelian anyons are engineered through defect lines rather than as excitations, non-Abelian error correction is not required. Instead the error correction problem is performed on the underlying Abelian model, allowing high noise thresholds to be realized.Comment: 11+10 pages, 14 figures; v2: accepted for publication in Phys. Rev. X; 4 new figures, performance of phase-gate explained in more detai

A Nonlinear Plancherel Theorem with Applications to Global Well-Posedness for the Defocusing Davey-Stewartson Equation and to the Inverse Boundary Value Problem of Calderón

We prove a Plancherel theorem for a nonlinear Fourier transform in two dimensions arising in the Inverse Scattering method for the defocusing Davey-Stewartson II equation. We then use it to prove global well-posedness and scattering in $L^2$ for defocusing DSII. This Plancherel theorem also implies global uniqueness in the inverse boundary value problem of Calder\'on in dimension $2$, for conductivities \sigma>0 with $\log \sigma \in \dot H^1$. The proof of the nonlinear Plancherel theorem includes new estimates on classical fractional integrals, as well as a new result on $L^2$-boundedness of pseudo-differential operators with non-smooth symbols, valid in all dimensions

Rectenna thermal model development

Deploying rectennas in space requires adapting existing designs developed for terrestrial applications to the space environment. One of the major issues in doing so is to understand the thermal performance of existing designs in the space environment. Toward that end, a 3D rectenna thermal model has been developed, which involves analyzing shorted rectenna elements and finite size rectenna element arrays. A shorted rectenna element is a single element whose ends are connected together by a material of negligible thermal resistance. A shorted element is a good approximation to a central element of a large array. This model has been applied to Brown's 2.45 GHz rectenna design. Results indicate that Brown's rectenna requires redesign or some means of enhancing the heat dissipation in order for the diode temperature to be maintained below 200 C above an output power density of 620 W/sq.m. The model developed in this paper is very general and can be used for the analysis and design of any type of rectenna design of any frequency

Para-Grassmann Variables and Coherent States

The definitions of para-Grassmann variables and q-oscillator algebras are recalled. Some new properties are given. We then introduce appropriate coherent states as well as their dual states. This allows us to obtain a formula for the trace of a operator expressed as a function of the creation and annihilation operators.Comment: This is a contribution to the Proc. of the O'Raifeartaigh Symposium on Non-Perturbative and Symmetry Methods in Field Theory (June 2006, Budapest, Hungary), published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

SPECIFICATION OF THE IMPACT OF SOCIOECONOMIC FACTORS ON CONSUMPTION OF THE ANIMAL AND VEGETABLE SOURCES OF PROTEIN

Food Consumption/Nutrition/Food Safety,