880 research outputs found
Spin-singlet Gaffnian wave function for fractional quantum Hall systems
We characterize in detail a wave function conceivable in fractional quantum
Hall systems where a spin or equivalent degree of freedom is present. This wave
function combines the properties of two previously proposed quantum Hall wave
functions, namely the non-Abelian spin-singlet state and the nonunitary
Gaffnian wave function. This is a spin-singlet generalization of the
spin-polarized Gaffnian, which we call the "spin-singlet Gaffnian" (SSG). In
this paper we present evidence demonstrating that the SSG corresponds to the
ground state of a certain local Hamiltonian, which we explicitly construct,
and, further, we provide a relatively simple analytic expression for the unique
ground-state wave functions, which we define as the zero energy eigenstates of
that local Hamiltonian. In addition, we have determined a certain nonunitary,
rational conformal field theory which provides an underlying description of the
SSG and we thus conclude that the SSG is ungapped in the thermodynamic limit.
In order to verify our construction, we implement two recently proposed
techniques for the analysis of fractional quantum Hall trial states: The "spin
dressed squeezing algorithm", and the "generalized Pauli principle".Comment: 15 pages, 2 figures. Version 3 fixes a typographical error in the
Hamiltonian, Eq 3. Version 2 incorporates referee and editorial suggestions.
The original title "Putting a Spin on the Gaffnian" was deemed to be too
inappropriate for PR
Composite fermion model for entanglement spectrum of fractional quantum Hall states
We show that the entanglement spectrum associated with a certain class of
strongly correlated many-body states --- the wave functions proposed by
Laughlin and Jain to describe the fractional quantum Hall effect --- can be
very well described in terms of a simple model of non-interacting (or weakly
interacting) composite fermions.Comment: 6 pages, 2 figure
Spinful Composite Fermions in a Negative Effective Field
In this paper we study fractional quantum Hall composite fermion
wavefunctions at filling fractions \nu = 2/3, 3/5, and 4/7. At each of these
filling fractions, there are several possible wavefunctions with different spin
polarizations, depending on how many spin-up or spin-down composite fermion
Landau levels are occupied. We calculate the energy of the possible composite
fermion wavefunctions and we predict transitions between ground states of
different spin polarizations as the ratio of Zeeman energy to Coulomb energy is
varied. Previously, several experiments have observed such transitions between
states of differing spin polarization and we make direct comparison of our
predictions to these experiments. For more detailed comparison between theory
and experiment, we also include finite-thickness effects in our calculations.
We find reasonable qualitative agreement between the experiments and composite
fermion theory. Finally, we consider composite fermion states at filling
factors \nu = 2+2/3, 2+3/5, and 2+4/7. The latter two cases we predict to be
spin polarized even at zero Zeeman energy.Comment: 17 pages, 5 figures, 4 tables. (revision: incorporated referee
suggestions, note added, updated references
Ferromagnetic-nematic order and strongly correlated phases of fermions in optical flux lattices
We study a model of a 2D ultracold atomic gas subject to an "optical flux
lattice": a laser configuration where Raman-dressed atoms experience a strong
artificial magnetic field. This leads to a bandstructure of narrow energy bands
with non-zero Chern numbers. We consider the case of two-level (spin-)
fermionic atoms in this lattice, interacting via a repulsive -wave contact
interaction. Atoms restricted to the lowest band are described by an effective
model of spinless fermions with interactions that couple states in a
momentum-dependent manner across the Brillouin zone; a consequence of the Raman
dressing of the two spin states. We present the results of detailed exact
diagonalization studies of the many-body states for a range of filling factors,
. First, we present evidence for the existence of a phase with coupled
ferromagnetic--nematic ordering, which was previously suggested by a mean-field
analysis. Second, we present evidence indicating the presence of a
Laughlin-like fractional quantum Hall state occurring at filling factor . Finally, we observe a charge density wave state at , which we
are able to cleanly distinguish from the Laughlin-like state by its
translational symmetry breaking and relatively small participation ratio
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Role for polo-like kinase 4 in mediation of cytokinesis.
The mitotic protein polo-like kinase 4 (PLK4) plays a critical role in centrosome duplication for cell division. By using immunofluorescence, we confirm that PLK4 is localized to centrosomes. In addition, we find that phospho-PLK4 (pPLK4) is cleaved and distributed to kinetochores (metaphase and anaphase), spindle midzone/cleavage furrow (anaphase and telophase), and midbody (cytokinesis) during cell division in immortalized epithelial cells as well as breast, ovarian, and colorectal cancer cells. The distribution of pPLK4 midzone/cleavage furrow and midbody positions pPLK4 to play a functional role in cytokinesis. Indeed, we found that inhibition of PLK4 kinase activity with a small-molecule inhibitor, CFI-400945, prevents translocation to the spindle midzone/cleavage furrow and prevents cellular abscission, leading to the generation of cells with polyploidy, increased numbers of duplicated centrosomes, and vulnerability to anaphase or mitotic catastrophe. The regulatory role of PLK4 in cytokinesis makes it a potential target for therapeutic intervention in appropriately selected cancers
A National Mentoring and Buddying Pilot Scheme for UK Early Career CS Academics
In the United Kingdom (UK), a thriving computer science education (CSE) community of practice is evolving, supported by national and international professional body/learned society specialist interest groups, and being developed through a number of CSE research and practice conferences. A key group within this emerging community of practice are early career academics who are required to overcoming significant obstacles in the early stages of their academic career, from developing an independent research career, delivering high quality learning and teaching, continuing their own professional development, alongside wider academic service commitments. Institutional-level, but generally subject-agnostic, support for early career colleagues in the UK is supplemented by nationwide developmental sessions and initiatives such as journal clubs. This poster reports on a pilot scheme to support early career CS academics through a mentoring scheme consisting of cross-institutional mentoring from experienced academics as well as buddying groups of similar career stage colleagues
Data science and AI: Trends analysis
This study has the primary goal to analyze the growth of data science through the main search trends. This study was conducted by defining in high level the concept of data science as well as its main components. Supported in those elements, we identified the main trends. We used mainly data from google trends to determine the evolution of search by topics., research area, or simple expressions. It allowed us to reckon that artificial intelligence (AI)suffered a lack of interest until 2012. Then it became an increasingly popular field since 2014. This is due to the progression of machine learning and data science. Results show a cumulative search of data science since 2012.info:eu-repo/semantics/acceptedVersio
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Uncovering the hidden costs of offshoring: The interplay of complexity, organizational design, and experience
This study investigates estimation errors due to hidden costs—the costs of implementation that are neglected in strategic decision-making processes—in the context of services offshoring. Based on data from the Offshoring Research Network, we find that decision makers are more likely to make cost-estimation errors given increasing configuration and task complexity in captive offshoring and offshore outsourcing, respectively. Moreover, we show that experience and a strong orientation toward organizational design in the offshoring strategy reduce the cost-estimation errors that follow from complexity. Our findings contribute to research on the effectiveness of sourcing and global strategies by stressing the importance of organizational design and experience in dealing with increasing complexity
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