Safe Sleep

Many parents and healthcare providers are either unsure of safe sleep practices or fail to implement them. This presentation will display safe sleep guidelines that are recommended by the American Academy of Pediatrics

Simulation of strongly correlated fermions in two spatial dimensions with fermionic Projected Entangled-Pair States

We explain how to implement, in the context of projected entangled-pair states (PEPS), the general procedure of fermionization of a tensor network introduced in [P. Corboz, G. Vidal, Phys. Rev. B 80, 165129 (2009)]. The resulting fermionic PEPS, similar to previous proposals, can be used to study the ground state of interacting fermions on a two-dimensional lattice. As in the bosonic case, the cost of simulations depends on the amount of entanglement in the ground state and not directly on the strength of interactions. The present formulation of fermionic PEPS leads to a straightforward numerical implementation that allowed us to recycle much of the code for bosonic PEPS. We demonstrate that fermionic PEPS are a useful variational ansatz for interacting fermion systems by computing approximations to the ground state of several models on an infinite lattice. For a model of interacting spinless fermions, ground state energies lower than Hartree-Fock results are obtained, shifting the boundary between the metal and charge-density wave phases. For the t-J model, energies comparable with those of a specialized Gutzwiller-projected ansatz are also obtained.Comment: 25 pages, 35 figures (revised version

New skyrmions in the attractive Hubbard model with broken SO(4) symmetry

The coexistence of superconducting and charge-density-wave order in the half-filled attractive Hubbard model is interpreted as a consequence of the pseudospin SU(2) symmetry spontaneously broken to a `hidden' subgroup U(1). By topological arguments we show that there must exist new skyrmion textures associated with this symmetry breakdown. This fact is illustrated via a non-linear $\sigma$-model. Unlike the spin textures previously known in an antiferromagnetic background, doping the model away from half-filling leads the new skyrmions to unwrap.Comment: 10 pages, 1 table, final version to be published in Phys. Lett.

Monte Carlo study of fermionic trions in a square lattice with harmonic confinement

We investigate the strong-coupling limit of a three-component Fermi mixture in an optical lattice with attractive interactions. In this limit bound states (trions) of the three components are formed. We derive an effective Hamiltonian for these composite fermions and show that it is asymptotically equivalent to an antiferromagnetic Ising model. By using Monte-Carlo simulations, we investigate the spatial arrangement of the trions and the formation of a trionic density wave (CDW), both in a homogeneous lattice and in the presence of an additional harmonic confinement. Depending on the strength of the confinement and on the temperature, we found several scenarios for the trionic distribution, including coexistence of disordered trions with CDW and band insulator phases. Our results show that, due to a proximity effect, staggered density modulations are induced in regions of the trap where they would not otherwise be present according to the local density approximation.Comment: 10 pages, 8 figure

Analysis of family engagement in the evaluation of organisational effectiveness in family businesses

Purpose: This elaboration features an attempt of describing the research sample’s uniformity and estimating the average engagement of family members in the family business’ functioning (hereinafter referred to as family engagement). The study’s context was based on a set of organisational effectiveness factors (identified independent variables) and an evaluation of their significance. In this paper, the effectiveness is deemed as the engagement of family members in the functioning of family businesses. Methodology: The paper presents the results of surveys conducted among 200 Polish family businesses with registered seats in two voivodeships. Organisational effectiveness was measured in terms of 8 key analysis fields identified. Findings: The paper presents the results of own research on organisational effectiveness in family businesses. It especially confirmed the alternative hypothesis that the dependent variable, i.e. family engagement, in terms of evaluating 8 independent variables using statistical tests, does not have a normal distribution. Practical Implications: The obtained results provide the basis for selection and future use of advanced statistical tests enabling the verification of a substantial dependency between the dependent variable (e.g. family engagement) and the independent variables identified within organisational effectiveness fields. Originality/Value: The conducted study supplements the knowledge on strategic management by specifying a set of family member engagement factors in family businesses. When analysing the widespread phenomenon of organisational effectiveness in family businesses, the authors analysed family engagement in terms of the effectiveness’ studied variables.peer-reviewe

SUPERFLUID CHARACTERISTICS OF INDUCED-PAIRING MODEL

We study the electromagnetic and thermodynamic properties of a model of coexisting local electron pairs and itinerant carriers coupled via the intersubsystem charge exchange. The calculations of the London penetration depth, the energy gap, the magnetic critical fields and the coherence length in the superconducting phase are performed. The effects of reduced binding energy of local pairs are discussed. The 'considered effective Hamiltonian of coexisting localized d-electrons and itinerant c-electrons can be written as where E0 measures the relative position of d-level with respect to the bottom of the c-electron band εk in the absence of interactions, is the chemical potential which ensures that a total number of particles is constant, i.e. n = n, -I-n a = (Σkσ (ck ckσ) + Σi σ (n ó)) /N, U is the effective on-site density interaction between d-electrons, t is the hopping integral for c-electrons and I0 is the intersubsystem charge exchange coupling. The Peierls factor in Eq. (1) account for the coupling of electrons to the magnetic field via its vector potential A(r). Φij = -fi g f' drA(r), and e is the electron charge. In analysis we used the variational approach which treats the on-site interaction term U exactl

Partially gapped fermions in 2D

We compute mean field phase diagrams of two closely related interacting fermion models in two spatial dimensions (2D). The first is the so-called 2D t-t'-V model describing spinless fermions on a square lattice with local hopping and density-density interactions. The second is the so-called 2D Luttinger model that provides an effective description of the 2D t-t'-V model and in which parts of the fermion degrees of freedom are treated exactly by bosonization. In mean field theory, both models have a charge-density-wave (CDW) instability making them gapped at half-filling. The 2D t-t'-V model has a significant parameter regime away from half-filling where neither the CDW nor the normal state are thermodynamically stable. We show that the 2D Luttinger model allows to obtain more detailed information about this mixed region. In particular, we find in the 2D Luttinger model a partially gapped phase that, as we argue, can be described by an exactly solvable model.Comment: v1: 36 pages, 10 figures, v2: minor corrections; equation references to arXiv:0903.0055 updated