247 research outputs found
Aharonov-Bohm effect for confined matter in lattice gauge theories
Gauge theories arise in physical systems displaying space-time local
symmetries. They provide a powerful description of important realms of physics
ranging from fundamental interactions, to statistical mechanics, condensed
matter and more recently quantum computation. As such, a remarkably deep
understanding has been achieved in the field. With the advent of quantum
technology, lower energy analogs, capable to capture important features of the
original quantum field theories through quantum simulation, have been
intensively studied. Here, we propose a specific scheme implementing an
analogic quantum simulation of lattice gauge theories constrained to mesoscopic
spatial scales. To this end, we study the dynamics of mesons residing in a
ring-shaped lattice of mesoscopic size pierced by an effective magnetic field.
In particular, we find a new type of Aharonov-Bohm effect that goes beyond the
particle-like effect and reflecting the the features of the confining gauge
potential. The coherence properties of the meson are quantified by the
persistent current and by specific features of the correlation functions. When
the magnetic field is quenched, Aharonov-Bohm oscillations and correlations
start a specific matter-wave current dynamics
A preliminary global hydrochemical comparison of lakes and reservoirs
Lakes and reservoirs are important for environmental anthropogenic functions in terms of agriculture and/or settlements. Here we present a first global overview of their chemistry by considering 1,508 water bodies, with data from 485 peer-reviewed publications from 1868 to 2020 and further five online databases. This work focusses on major ions (Ca2+, Mg2+, Na+, K+, HCO3-&CO32-, Clâ, SO42-) and investigates analogies as well as differences between lakes and reservoirs. We applied a Principal Component Analysis (PCA) to group both types of water bodies and to find differences and similarities. The PCA identified fewer variabilities for major ions in reservoirs than in lakes. Moreover, our analyses showed that lakes generally have more total dissolved solids (TDS). Such higher TDS loads in lakes could result from more diverse (and less controlled) inputs from larger catchments and from longer lasting interactions with thicker internal sediment layers. Global median geochemical compositions identified both reservoirs and lakes as calcium-bicarbonate-type waters. This first synthesis provides a basis for future studies and may serve as the start of a global database on these important water bodies
Inhomogeneous chiral symmetry breaking in noncommutative four fermion interactions
The generalization of the Gross-Neveu model for noncommutative 3+1 space-time
has been analyzed. We find indications that the chiral symmetry breaking occurs
for an inhomogeneous background as in the LOFF phase in condensed matter.Comment: 17 pages, 2 figures, published version, minor correction
Nonuniform symmetry breaking in noncommutative theory
The spontaneous symmetry breaking in noncommutative theory
has been analyzed by using the formalism of the effective action for composite
operators in the Hartree-Fock approximation. It turns out that there is no
phase transition to a constant vacuum expectation of the field and the broken
phase corresponds to a nonuniform background. By considering the generated mass gap depends on the angles among
the momenta and and the noncommutativity parameter
. The order of the transition is not easily determinable in our
approximation.Comment: 18 pages, 4 figures, added reference
Non-commutative dynamics and roton-like spectra in bosonic and fermionic condensates
The relation between symmetry breaking in non-commutative cut-off field
theories and transitions to inhomogeneous phases in condensed matter is
discussed. The non-commutative dynamics can be regarded as an effective
description of the mechanisms which lead to inhomogeneous phase transitions and
their relation to the roton-like excitation spectrum. The typical
infrared-ultraviolet mixing in non-commutative theories contains the peculiar
ingredients to describe the interplay between short and long distance particle
interactions which is responsible for the non-uniform background and the roton
spectrum both in bosonic and fermionic condensates.Comment: 4 Pages, no figure
Gluon condensation and deconfinement critical density in nuclear matter
An upper limit to the critical density for the transition to the deconfined
phase, at zero temperature, has been evaluated by analyzing the behavior of the
gluon condensate in nuclear matter. Due to the non linear baryon density
effects, the upper limit to the critical density, \rho_c turns out about nine
times the saturation density, rho_0 for the value of the gluon condensate in
vacuum =0.012 GeV^4. For neutron matter \rho_c \simeq 8.5
\rho_0. The dependence of the critical density on the value of the gluon
condensate in vacuum is studied.Comment: Published version, 11 pages, 2 eps figure
Rechallenge of denosumab in advanced giant cell tumor of the bone after atypical femur fracture: A case report and review of literature
Giant cell tumor of the bone (GCTB) is a locally aggressive neoplasm where surgery is often curative. However, it can rarely give rise to distant metastases. Currently, the only available active therapeutic option for unresectable GCTB is denosumab, an anti-RANKL monoclonal antibody that dampens the aggressive osteolysis typically seen in this disease. For advanced/metastatic GCTB, denosumab should be continued lifelong, and although it is usually well tolerated, important questions may arise about the long-term safety of this drug. In fact, uncommon but severe toxicities can occur and eventually lead to denosumab discontinuation, such as atypical fracture of the femur (AFF). The optimal management of treatment-related AFF is a matter of debate, and to date, it is unknown whether reintroduction of denosumab at disease progression is a clinically feasible option, as no reports have been provided so far. Hereinafter, we present a case of a patient with metastatic GCTB who suffered from AFF after several years of denosumab; we describe the clinical features, orthopedic treatment, and oncological outcomes, finally providing the first evidence that denosumab rechallenge after AFF occurrence may be a safe and viable option at GCTB progression
Pest categorisation of Conotrachelus nenuphar
The EFSA Panel on Plant Health performed a pest categorisation of Conotrachelus nenuphar (Herbst)
(Coleoptera: Curculionidae), for the EU. C. nenuphar is a well-defined species, recognised as a serious
pest of stone and pome fruit in the USA and Canada where it also feeds on a range of other hosts
including soft fruit (e.g. Ribes, Fragaria) and wild plants (e.g. Crataegus). Adults, which are not good
flyers, feed on tender twigs, flower buds and leaves. Females oviposit into host fruit; if oviposition
occurs in young fruit, the fruit usually falls prematurely reducing yield; oviposition in older fruit causes
surface blemishes and the fruit distorts as it develops reducing marketability. Larvae develop within
host fruit but exit to pupate in soil. Adults overwinter in leaf litter. C. nenuphar is not known to occur
in the EU and is listed in Annex IAI of Council Directive 2000/29/EC. Fruit infested shortly before
harvest and soil with leaf litter accompanying plants for planting could potentially provide a pathway
into the EU. Considering the climatic similarities between North America and Europe, and that hosts
occur widely within the EU, C. nenuphar has potential to establish within the EU. There could be one
or two generations per year, as in North America. Impacts could be expected, e.g. in Prunus spp. and
apples. Phytosanitary measures are available to reduce the likelihood of introduction of C. nenuphar.
All of the criteria assessed by EFSA for consideration as a potential Union quarantine pest are met.
C. nenuphar does not meet the criteria of occurring in the EU nor plants for planting being the
principal means of spread. Hence it does not satisfy all of the criteria that are within the remit of EFSA
to assess for it to be regarded as a Union regulated non-quarantine pest (RNQP)
Pest categorisation of Sternochetus mangiferae
The European Commission requested EFSA to conduct a pest categorisation of Sternochetus mangiferae
(Coleoptera: Curculionidae), a monophagous pest weevil whose larvae exclusively feed on mango seeds,
whereas adults feed on mango foliage. S. mangiferae is a species with reliable methods available for
identification. It is regulated in the EU by Council Directive 2000/29/EC where it is listed in Annex IIB as a
harmful organism whose introduction into EU Protected Zones (PZ) (Alentejo, Algarve and Madeira in
Portugal, and Granada and Malaga in Spain) is banned. S. mangiferae is native to South East Asia and
has spread to other mango-growing areas in Africa, South America and Oceania, causing significant
damage. Larvae of S. mangiferae have been detected several times in mango fruit imported into the EU.
In 2013, an outbreak was declared in one PZ in Spain. Official measures taken achieved eradication,
which was officially declared in January 2018. The EFSA Plant Health Panel concludes that S. mangiferae
could establish again and spread in the mango-growing areas of southern EU. Considering the criteria
within the remit of EFSA to assess the status as a potential Union quarantine pest (QP), as a potential
protected zone quarantine pest (PZQP) or as a potential regulated non-quarantine pest (RNQP),
S. mangiferae meets with no uncertainties the criteria for consideration as a potential Union QP, as it is
absent from the EU, potential pathways for entry exist, and its establishment would cause an economic
impact. The criterion of the pest being present in the EU, which is a prerequisite for RNQP and PZ QP, is
not met
Pest categorisation of Acrobasis pirivorella
The European Commission requested EFSA to conduct a pest categorisation of Acrobasis pirivorella
(Lepidoptera: Pyralidae), a monophagous moth whose larvae exclusively feed on developing buds,
flowers, and fruits of cultivated and wild Pyrus spp. A. pirivorella is a species with reliable methods
available for identification. A. pirivorella occurs in north-east Asia only, causing significant damage in
cultivated pears. It is regulated in the EU by Council Directive 2000/29/EC where it is listed in Annex IIAI.
Within this regulation, plants for planting of Pyrus spp. is a closed pathway. This species has never been
reported by Europhyt. Fruits and cut branches of Pyrus spp. are open pathways. Biotic and abiotic
conditions are conducive for establishment and spread of A. pirivorella in the EU. Were A. pirivorella to
establish, impact on pear production is expected. Considering the criteria within the remit of EFSA to
assess its regulatory plant health status, A. pirivorella meets the criteria for consideration as a potential
Union quarantine pest (it is absent from the EU, potential pathways exist and its establishment would
cause an economic impact). Given that A. pirivorella is not known to occur in the EU, it fails to meet some
of the criteria required for regulated non-quarantine pest (RNQP) status
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