2,791 research outputs found
Rigorous Calculations of Non-Abelian Statistics in the Kitaev Honeycomb Model
We develop a rigorous and highly accurate technique for calculation of the
Berry phase in systems with a quadratic Hamiltonian within the context of the
Kitaev honeycomb lattice model. The method is based on the recently found
solution of the model which uses the Jordan-Wigner-type fermionization in an
exact effective spin-hardcore boson representation. We specifically simulate
the braiding of two non-Abelian vortices (anyons) in a four vortex system
characterized by a two-fold degenerate ground state. The result of the braiding
is the non-Abelian Berry matrix which is in excellent agreement with the
predictions of the effective field theory. The most precise results of our
simulation are characterized by an error on the order of or lower. We
observe exponential decay of the error with the distance between vortices,
studied in the range from one to nine plaquettes. We also study its correlation
with the involved energy gaps and provide preliminary analysis of the relevant
adiabaticity conditions. The work allows to investigate the Berry phase in
other lattice models including the Yao-Kivelson model and particularly the
square-octagon model. It also opens the possibility of studying the Berry phase
under non-adiabatic and other effects which may constitute important sources of
errors in topological quantum computation.Comment: 27 pages, 9 figures, 3 appendice
NEW CONCEPTS IN THE TECHNOLOGICAL DEVELOPMENT OF AGRICULTURE
Agriculture in the Republic of Macedonia is in a constant development crisis, based on structural agri-policy origin. Agricultural holdings occur in several structures, such as: very small individual holdings (farms) that use about 80% of the agricultural land; agricultural companies; and several cooperatives that use about 20% of the best quality agricultural land in the country. The industrial labor organization in the some of the agricultural corporations: disrupts the natural cycle of the plant and animal production, increases the input, decreases the production capacity of the land and creates environmental issues. The phases that include reproduction and milk production, as phases of the farming process, are especially expensive and require individual treatment of animals. The trend of development of village structure which can encompass the principles of agriculturalproduction is negative. The small land property structure, which is worsening each year, cause deprofessionalization, specially in the hilly and mountain regions. Therefore, strategy for technological development in agriculture is proposed in this paper. The strategy is expected to contribute in the development and strengthening of agriculture in the villages in accordance to the west European examples based on cooperative investment and ownership
Cerebellar ataxia with spasmodic cough: a new form of dominant ataxia
Background: Although mentioned in most series, “pure”
autosomal dominant cerebellar ataxias, except spinocerebellar
ataxia type 6, are difficult to differentiate on clinical
grounds.
Objective: To describe Portuguese families with a peculiar
pure form of dominant ataxia that, to our knowledge,
has never been documented before and in which
cerebellar signs are preceded by spasmodic cough.
Patients: Through a population-based survey of hereditary
ataxias in Portugal, we identified 19 patients in
6 families with this particular disorder.
Results: The majority of patients had a pure late-onset
ataxia with a benign evolution. In all of the families, attacks
of spasmodic coughing preceded ataxia for 1 to 3
decades and were a reliable marker of the disease. In Portugal,
this form of ataxia accounts for 2.7% of all of the
dominant ataxias.
Conclusions: The families that we describe shared
some relevant clinical and imagiological features with
spinocerebellar ataxia type 5 and the recently described
spinocerebellar ataxia type 20, allelic to spinocerebellar
ataxia type 5. Spinocerebellar ataxia types 5 and 20
could be different phenotypic expressions of the same
molecular disorder. The association of a dominant
ataxia with spasmodic cough is rare but probably underdiagnosed.Fundação para a Ciência e Tecnologi
SÍNDROME DE HIPERPERFUSÃO CEREBRAL APÓS ANGIOPLASTIA CAROTÍDEA: COMPLICAÇÃO POTENCIALMENTE EVITÁVEL
Limits on intrinsic magnetism in graphene
We have studied magnetization of graphene nanocrystals obtained by sonic
exfoliation of graphite. No ferromagnetism is detected at any temperature down
to 2 K. Neither do we find strong paramagnetism expected due to the massive
amount of edge defects. Rather, graphene is strongly diamagnetic, similar to
graphite. Our nanocrystals exhibit only a weak paramagnetic contribution
noticeable below 50K. The measurements yield a single species of defects
responsible for the paramagnetism, with approximately one magnetic moment per
typical graphene crystallite.Comment: 2nd version, modified in response to comment
Merkel cell polyomavirus large T antigen disrupts lysosome clustering by translocating human Vam6p from the cytoplasm to the nucleus
Merkel cell polyomavirus (MCV) has been recently described as the cause for most human Merkel cell carcinomas. MCV is similar to simian virus 40 (SV40) and encodes a nuclear large T (LT) oncoprotein that is usually mutated to eliminate viral replication among tumor-derived MCV. We identified the hVam6p cytoplasmic protein involved in lysosomal processing as a novel interactor with MCV LT but not SV40 LT. hVam6p binds through its clathrin heavy chain homology domain to a unique region of MCV LT adjacent to the retinoblastoma binding site. MCV LT translocates hVam6p to the nucleus, sequestering it from involvement in lysosomal trafficking. A naturally occurring, tumor-derived mutant LT (MCV350) lacking a nuclear localization signal binds hVam6p but fails to inhibit hVam6p-induced lysosomal clustering. MCV has evolved a novel mechanism to target hVam6p that may contribute to viral uncoating or egress through lysosomal processing during virus replication
Conservative Approach to Unilateral Condylar Fracture in a Growing Patient: A 2.5-Year Follow Up
Condylar fractures in children are especially important because of the risk of a mandibular growth-center being affected in the condylar head, which can lead to growth retardation and facial asymmetry. The purpose of this article is to follow up the two and half year clinical and radiological evaluation of the conservative treatment of a 10 year-old patient, who had a unilateral green-stick type fracture. The patient presented with painful facial swelling localized over the left condylar region, limited mouth-opening and mandibular deviation to the left. Panoramic radiography and computed tomography confirmed the diagnosis of incomplete fracture on the left condyle with one side of the bone fractured and the other bent. Closed reduction was chosen to allow for initial fibrous union of the fracture segments and remodeling with a normal functional stimulus. A non-rigid mandibular splint was applied in order to remove the direct pressure on the fracture side of the mandible. Clinical and radiologic examination after 30 months revealed uneventful healing with reduction of the condylar head and remodeling of the condylar process following conservative treatment
Robotic Wireless Sensor Networks
In this chapter, we present a literature survey of an emerging, cutting-edge,
and multi-disciplinary field of research at the intersection of Robotics and
Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor
Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system
that aims to achieve certain sensing goals while meeting and maintaining
certain communication performance requirements, through cooperative control,
learning and adaptation. While both of the component areas, i.e., Robotics and
WSN, are very well-known and well-explored, there exist a whole set of new
opportunities and research directions at the intersection of these two fields
which are relatively or even completely unexplored. One such example would be
the use of a set of robotic routers to set up a temporary communication path
between a sender and a receiver that uses the controlled mobility to the
advantage of packet routing. We find that there exist only a limited number of
articles to be directly categorized as RWSN related works whereas there exist a
range of articles in the robotics and the WSN literature that are also relevant
to this new field of research. To connect the dots, we first identify the core
problems and research trends related to RWSN such as connectivity,
localization, routing, and robust flow of information. Next, we classify the
existing research on RWSN as well as the relevant state-of-the-arts from
robotics and WSN community according to the problems and trends identified in
the first step. Lastly, we analyze what is missing in the existing literature,
and identify topics that require more research attention in the future
Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS
The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured
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