287 research outputs found
Edge excitations and Topological orders in rotating Bose gases
The edge excitations and related topological orders of correlated states of a
fast rotating Bose gas are studied. Using exact diagonalization of small
systems, we compute the energies and number of edge excitations, as well as the
boson occupancy near the edge for various states. The chiral Luttinger-liquid
theory of Wen is found to be a good description of the edges of the bosonic
Laughlin and other states identified as members of the principal Jain sequence
for bosons. However, we find that in a harmonic trap the edge of the state
identified as the Moore-Read (Pfaffian) state shows a number of anomalies. An
experimental way of detecting these correlated states is also discussed.Comment: Results extended to larger systems. Improved presentatio
Symmetry breaking in small rotating cloud of trapped ultracold Bose atoms
We study the signatures of rotational and phase symmetry breaking in small
rotating clouds of trapped ultracold Bose atoms by looking at rigorously
defined condensate wave function. Rotational symmetry breaking occurs in narrow
frequency windows, where the ground state of the system has degenerated with
respect to the total angular momentum, and it leads to a complex wave function
that exhibits vortices clearly seen as holes in the density, as well as
characteristic vorticity. Phase symmetry (or gauge symmetry) breaking, on the
other hand, is clearly manifested in the interference of two independent
rotating clouds.Comment: 4 pages, 2 figure
Non-Abelian spin singlet states of two-component Bose gases in artificial gauge fields
We study strongly correlated phases of a pseudo-spin-1/2 Bose gas in an
artificial gauge field using the exact diagonalization method. The atoms are
confined in two dimensions and interact via a two-body contact potential. In
Abelian gauge fields, pseudo-spin singlets are favored by pseudo-spin
independent interactions. We find a series of incompressible phases at fillings
\nu=2k/3. By comparison with the non-Abelian spin singlet (NASS) states,
constructed as zero-energy eigenstates of a (k+1)-body contact interaction, we
classify the non-trivial topology of the states. An additional spin-orbit
coupling is shown to switch between NASS-like states and spin-polarized phases
from the Read-Rezayi series.Comment: 4 pages, 3 figure
Diet-derived bioavailable metabolites to tackle diabetes
Funding Information: Funding: This study was funded by Fundação para a Ciência e Tecnologia (FCT)/Ministério da Ciência e do Ensino Superior, grant numbers PTDC/BIA-MOL/31104/2017 (RM) and UIDB/04567/2020 and UIDP/ 04567/2020 (CBIOS). iNOVA4Health Research Unit (LISBOA—01–0145—FEDER—007344), which is cofunded by FCT/Ministério da Ciência e do Ensino Superior, through national funds, and by FEDER under the PT2020 Partnership Agreement, is also acknowledged. Authors would like to acknowledge FCT for the financial support of AFR (PD/BD/135504/2018); SF (UI/BD/151421/2021), and RM (CEEC/04567/CBIOS/2020).Diabetes remains one of the leading causes of deaths and co-morbidities in the world, with tremendous human, social and economic costs. Therefore, despite therapeutics and technological advancements, improved strategies to tackle diabetes management are still needed. One of the suggested strategies is the consumption of (poly)phenols. Positive outcomes of dietary (poly)phenols have been pointed out towards different features in diabetes. This is the case of ellagitannins, which are present in numerous foodstuffs such as pomegranate, berries, and nuts. Ellagitannins have been reported to have a multitude of effects on metabolic diseases. However, these compounds have high molecular weight and do not reach circulation at effective concentrations, being metabolized in smaller compounds. After being metabolized into ellagic acid in the small intestine, the colonic microbiota hydrolyzes and metabolizes ellagic acid into dibenzopyran-6-one derivatives, known as urolithins. These low molecular weight compounds reach circulation in considerable concentrations ranging until micromolar levels, capable of reaching target tissues. Different urolithins are formed throughout the metabolization process, but urolithin A, isourolithin A, and urolithin B, and their phase-II metabolites are the most frequent ones. In recent years, urolithins have been the focus of attention in regard to their effects on a multiplicity of chronic diseases, including cancer and diabetes. In this review, we will discuss the latest advances about the protective effects of urolithins on diabetes.publishersversionpublishe
Ordered structures in rotating ultracold Bose gases
The characterization of small samples of cold bosonic atoms in rotating
microtraps has recently attracted increasing interest due to the possibility to
deal with a few number of particles per site in optical lattices. We analyze
the evolution of ground state structures as the rotational frequency
increases. Various kinds of ordered structures are observed. For atoms,
the standard scenario, valid for large sytems, is absent, and only gradually
recovered as increases. The vortex contribution to the total angular
momentum as a function of ceases to be an increasing function of
, as observed in experiments of Chevy {\it et al.} (Phys. Rev. Lett.
85, 2223 (2000)). Instead, for small , it exhibits a sequence of peaks
showing wide minima at the values of , where no vortices appear.Comment: 35 pages, 17 figure
Vortex nucleation in mesoscopic Bose superfluid and breaking of the parity symmetry
We analyze vortex nucleation in mezoscopic 2D Bose superfluid in a rotating
trap. We explicitly include a weakly anisotropic stirring potential, breaking
thus explicitly the axial symmetry. As the rotation frequency passes the
critical value the system undergoes an extra symmetry
change/breaking. Well below the ground state is properly described
by the mean field theory with an even condensate wave function. Well above
the MF solution works also well, but the order parameter becomes
odd. This phenomenon involves therefore a discrete parity symmetry breaking. In
the critical region the MF solutions exhibit dynamical instability. The true
many body state is a strongly correlated entangled state involving two
macroscopically occupied modes (eigenstates of the single particle density
operator). We characterize this state in various aspects: i) the eligibility
for adiabatic evolution; ii) its analytical approximation given by the
maximally entangled combination of two single modes; and finally iii) its
appearance in particle detection measurements.Comment: 14 pages, 27 figure
Low energy excitations of double quantum dots in the lowest Landau level regime
We study the spectrum and magnetic properties of double quantum dots in the
lowest Landau level for different values of the hopping and Zeeman parameters
by means of exact diagonalization techniques in systems of N=6 and N=7
electrons and filling factor close to 2. We compare our results with those
obtained in double quantum layers and single quantum dots. The Kohn theorem is
also discussed.Comment: 23 pages, 4 figures, 1 table; references added; journal versio
Scissors mode of trapped dipolar gases
We study the scissors modes of dipolar boson and fermion gases trapped in a
spherically symmetric potential. We use the harmonic oscillator states to solve
the time-dependent Gross-Pitaevskii equation for bosons and the time-dependent
Hartree-Fock equation for fermions. It is pointed out that the scissors modes
of bosons and fermions can be of quite different nature
(Poly)phenol-digested metabolites modulate alpha-synuclein toxicity by regulating proteostasis
We acknowledge Rita Ramos for support with qRT-PCR and Regina Menezes for the selection of primers; Antonio Temudo and Ana M. Nascimento for imaging support; The IMM-JLA Flow Cytometry Facility. We also thank Prof. Kuninori Suzuki (Tokyo Institute of Technology, Yokohama, Japan) for the 2xmCherry-ATG8 plasmid. TFO is supported by the DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain. This work was supported by Fundacao para a Ciencia e Tecnologia [iNOVA4Health: UID/Multi/04462/2013, SFRH/BD/73429/2010 and IMM/BI/78-2017 to DM, SFRH/BD/86584/2012 to IF, IF/01097/2013 to CNS, SFRH/BPD/35767/2007 and SFRH/BPD/101646/2014 to ST]. BacHBerry FP7 KBBE-2013-7 613793 to CNS, DM and CJ, Marie Curie International Reintegration Grant and an EMBO Installation Grant to TFO. TFO is supported by the DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain. The author(s) would like to acknowledge the STSM to AFA and networking support by the COST Action FA 1403 POSITIVe (Interindividual variation in responseto consumption of plant food bioactives and determinants involved), supported by COST (European Cooperation in Science and Technology).Parkinson's disease (PD) is an age-related neurodegenerative disease associated with the misfolding and aggregation of alpha-synuclein (aSyn). The molecular underpinnings of PD are still obscure, but nutrition may play an important role in the prevention, onset, and disease progression. Dietary (poly)phenols revert and prevent age-related cognitive decline and neurodegeneration in model systems. However, only limited attempts were made to evaluate the impact of digestion on the bioactivities of (poly)phenols and determine their mechanisms of action. This constitutes a challenge for the development of (poly)phenol-based nutritional therapies. Here, we subjected (poly)phenols from Arbutus unedo to in vitro digestion and tested the products in cell models of PD based on the cytotoxicity of aSyn. The (poly)phenol-digested metabolites from A. unedo leaves (LPDMs) effectively counteracted aSyn and H2O2 toxicity in yeast and human cells, improving viability by reducing aSyn aggregation and inducing its clearance. In addition, LPDMs modulated pathways associated with aSyn toxicity, such as oxidative stress, endoplasmic reticulum (ER) stress, mitochondrial impairment, and SIR2 expression. Overall, LPDMs reduced aSyn toxicity, enhanced the efficiency of ER-associated protein degradation by the proteasome and autophagy, and reduced oxidative stress. In total, our study opens novel avenues for the exploitation of (poly)phenols in nutrition and health.publishersversionpublishe
Fractional quantum Hall states of few bosonic atoms in geometric gauge fields
We employ the exact diagonalization method to analyze the possibility of
generating strongly correlated states in two-dimensional clouds of ultracold
bosonic atoms which are subjected to a geometric gauge field created by
coupling two internal atomic states to a laser beam. Tuning the gauge field
strength, the system undergoes stepwise transitions between different ground
states, which we describe by analytical trial wave functions, amongst them the
Pfaffian, the Laughlin, and a Laughlin quasiparticle many-body state. The
adiabatic following of the center of mass movement by the lowest energy dressed
internal state, is lost by the mixing of the second internal state. This
mixture can be controlled by the intensity of the laser field. The
non-adiabaticity is inherent to the considered setup, and is shown to play the
role of circular asymmetry. We study its influence on the properties of the
ground state of the system. Its main effect is to reduce the overlap of the
numerical solutions with the analytical trial expressions by occupying states
with higher angular momentum. Thus, we propose generalized wave functions
arising from the Laughlin and Pfaffian wave function by including components,
where extra Jastrow factors appear, while preserving important features of
these states. We analyze quasihole excitations over the Laughlin and
generalized Laughlin states, and show that they possess effective fractional
charge and obey anyonic statistics. Finally, we study the energy gap over the
Laughlin state as the number of particles is increased keeping the chemical
potential fixed. The gap is found to decrease as the number of particles is
increased, indicating that the observability of the Laughlin state is
restricted to a small number of particles.Comment: 28 pages, 16 figure
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