1,633 research outputs found
Parity detection and entanglement with a Mach-Zehnder interferometer
A parity meter projects the state of two qubits onto two subspaces with
different parities, the states in each parity class being indistinguishable. It
has application in quantum information for its entanglement properties. In our
work we consider the electronic Mach-Zehnder interferometer (MZI) coupled
capacitively to two double quantum dots (DQDs), one on each arm of the MZI.
These charge qubits couple linearly to the charge in the arms of the MZI. A key
advantage of an MZI is that the qubits are well separated in distance so that
mutual interaction between them is avoided. Assuming equal coupling between
both DQDs and the arms and the same bias for each DQD, this setup usually
detects three different currents, one for the odd states and two for each even
state. Controlling the magnetic flux of the MZI, we can operate the MZI as a
parity meter: only two currents are measured at the output, one for each parity
class. In this configuration, the MZI acts as an ideal detector, its Heisenberg
efficiency being maximal. For a class of initial states, the initially
unentangled DQDs become entangled through the parity measurement process with
probability one.Comment: 9 pages, 2 figure
Clinical, biochemical, and genetic spectrum of seven patients with NFU1 deficiency
Disorders of the mitochondrial energy metabolism are clinically and genetically heterogeneous. An increasingly recognized subgroup is caused by defective mitochondrial iron-sulfur (Fe-S) cluster biosynthesis, with defects in 13 genes being linked to human disease to date. Mutations in three of them, NFU1, BOLA3, and IBA57, affect the assembly of mitochondrial [4Fe-4S] proteins leading to an impairment of diverse mitochondrial metabolic pathways and ATP production. Patients with defects in these three genes present with lactic acidosis, hyperglycinemia, and reduced activities of respiratory chain complexes I and II, the four lipoic acid-dependent 2-oxoacid dehydrogenases and the glycine cleavage system (GCS). To date, five different NFU1 pathogenic variants have been reported in 15 patients from 12 families. We report on seven new patients from five families carrying compound heterozygous or homozygous pathogenic NFU1 mutations identified by candidate gene screening and exome sequencing. Six out of eight different disease alleles were novel and functional studies were performed to support the pathogenicity of five of them. Characteristic clinical features included fatal infantile encephalopathy and pulmonary hypertension leading to death within the first 6 months of life in six out of seven patients. Laboratory investigations revealed combined defects of pyruvate dehydrogenase complex (five out of five) and respiratory chain complexes I and II+III (four out of five) in skeletal muscle and/or cultured skin fibroblasts as well as increased lactate (five out of six) and glycine concentration (seven out of seven). Our study contributes to a better definition of the phenotypic spectrum associated with NFU1 mutations and to the diagnostic workup of future patients
Phase diagram for non-axisymmetric plasma balls
Plasma balls and rings emerge as fluid holographic duals of black holes and
black rings in the hydrodynamic/gravity correspondence for the Scherk-Schwarz
AdS system. Recently, plasma balls spinning above a critical rotation were
found to be unstable against m-lobed perturbations. In the phase diagram of
stationary solutions the threshold of the instability signals a bifurcation to
a new phase of non-axisymmetric configurations. We find explicitly this family
of solutions and represent them in the phase diagram. We discuss the
implications of our results for the gravitational system. Rotating
non-axisymmetric black holes necessarily radiate gravitational waves. We thus
emphasize that it would be important, albeit possibly out of present reach, to
have a better understanding of the hydrodynamic description of gravitational
waves and of the gravitational interaction between two bodies. We also argue
that it might well be that a non-axisymmetric m-lobed instability is also
present in Myers-Perry black holes for rotations below the recently found
ultraspinning instability.Comment: 1+22 pages, 3 figures. v2: minor corrections and improvements,
matches published versio
Continuous Symmetry Breaking in a Trapped-Ion Spin Chain
One-dimensional systems exhibiting a continuous symmetry can host quantum
phases of matter with true long-range order only in the presence of
sufficiently long-range interactions. In most physical systems, however, the
interactions are short-ranged, hindering the emergence of such phases in one
dimension. Here we use a one-dimensional trapped-ion quantum simulator to
prepare states with long-range spin order that extends over the system size of
up to spins and is characteristic of the continuous symmetry-breaking
phase of matter. Our preparation relies on simultaneous control over an array
of tightly focused individual-addressing laser beams, generating long-range
spin-spin interactions. We also observe a disordered phase with frustrated
correlations. We further study the phases at different ranges of interaction
and the out-of-equilibrium response to symmetry-breaking perturbations. This
work opens an avenue to study new quantum phases and out-of-equilibrium
dynamics in low-dimensional systems
Professionalism, golf coaching and a master of science degree
A distinction can be made between 'professionalisation', which is concerned with occupational status and standing, and 'professionalism,' which refers to matters of quality and standards of practice (especially specialized knowledge, ethics and altruism). The purpose of this stimulus article is to present key features of contemporary medical professionalism as a basis for critically reflecting on discourse associated with Tiger Woods' current coach, Sean Foley. It is suggested that that provision of a Master of Science degree in golf teaching/coaching would facilitate the development of 'professionalism' in golf coaches
Observing Brane Inflation
Linking the slow-roll scenario and the Dirac-Born-Infeld scenario of
ultra-relativistic roll (where, thanks to the warp factor, the inflaton moves
slowly even with an ultra-relativistic Lorentz factor), we find that the KKLMMT
D3/anti-D3 brane inflation is robust, that is, enough e-folds of inflation is
quite generic in the parameter space of the model. We show that the
intermediate regime of relativistic roll can be quite interesting
observationally. Introducing appropriate inflationary parameters, we explore
the parameter space and give the constraints and predictions for the
cosmological observables in this scenario. Among other properties, this
scenario allows the saturation of the present observational bound of either the
tensor/scalar ratio r (in the intermediate regime) or the non-Gaussianity f_NL
(in the ultra-relativistic regime), but not both.Comment: 31 pages, 12 figures; typo correcte
Lifetime of Stringy de Sitter Vacua
In this note we perform a synopsis of the life-times from vacuum decay of
several de Sitter vacuum constructions in string/M-theory which have a single
dS minimum arising from lifting a pre-existing AdS extremum and no other local
minima existent after lifting. For these vacua the decay proceeds via a
Coleman--De Luccia instanton towards the universal Minkowski minimum at
infinite volume. This can be calculated using the thin--wall approximation,
provided the cosmological constant of the local dS minimum is tuned
sufficiently small. We compare the estimates for the different model classes
and find them all stable in the sense of exponentially long life times as long
as they have a very small cosmological constant and a scale of supersymmetry
breaking > TeV.Comment: 1+16 pages, 2 figures, LaTeX, uses JHEP3 class, v2: references added,
inclusion of an additional subclass of de Sitter vacu
Ion exchange membranes derived from sulfonated polyaramides
Homo- and both random and block copolyaramides of high molecular weights, with sulfonated moieties in the backbone, were obtained by low temperature polycondensation technique in a dipolar aprotic solvent (NMP) using (a) free aromatic diamines in the presence of pyridine as acid acceptor and (b) N,N ′-bis-trimethylsilyl derivatives of the diamines without additional acid acceptor. The addition of low molecular weight electrolytes (LiCl or CaCl2) and in some cases trimesoyl chloride to the reaction mixture was found to be favorable for the synthesis of high molecular weight polyamides. The materials had a theoretical ion exchange capacity of up to 3.14 meq/g. The membranes were characterized in terms of morphology, thermal stability, water-uptake, and ion exchange capacities.Fil: Taeger, A.. Institute of Polymer Research Dresden; AlemaniaFil: Vogel, C.. Institute of Polymer Research Dresden; AlemaniaFil: Lehmann, D.. Institute of Polymer Research Dresden; AlemaniaFil: Jehnichen, D.. Institute of Polymer Research Dresden; AlemaniaFil: Komber, H.. Institute of Polymer Research Dresden; AlemaniaFil: Meier Haack, J.. Institute of Polymer Research Dresden; AlemaniaFil: Ochoa, Nelio Ariel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - San Luis. Instituto de FÃsica Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias FÃsico Matemáticas y Naturales. Instituto de FÃsica Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Nunes, S.P.. GKSS Research Center; AlemaniaFil: Peinemann, K.-V.. GKSS Research Center; Alemani
Response of Common and Rare Beetle Species to Tree Species and Vertical Stratification in a Floodplain Forest
Vertical stratification and host tree species are factors with a high influence on the structure of communities of xylobiont beetles. However, little is known about how this influence varies between common and rare species. Based on estimated species richness, we compared alpha and beta diversity patterns of common and rare species in the canopy of the Leipzig floodplain forest to assess their response to vertical stratification and tree species. We used two measures of rarity: threat level in red lists and abundance based on octaves. The understory displayed a significantly higher number of common species than the canopy strata. Conversely, the canopy strata harbored a higher number of rare species. Turnover was always dominant over richness differences in beta diversity partitions. Using Raup–Crick null models and non-metric multidimensional scaling, we found that the vertical strata accounted for 19% of the overall beta diversity of common species and for 15% of the overall beta diversity of rare species. The tree species accounted for 7% of the overall beta diversity of the common species and 3% of the beta diversity of the rare species. Our results indicate that studies carried out in the understory alone do not allow drawing conclusions regarding the biodiversity in the canopy strata, and thus regarding the overall community structure of xylobiont beetles in the canopy.This study is kindly supported by the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Research Foundation (FZT 118). The Article processing charges were funded by the Open Science Office of the Leipzig University Library.info:eu-repo/semantics/publishedVersio
Loop Groups, Kaluza-Klein Reduction and M-Theory
We show that the data of a principal G-bundle over a principal circle bundle
is equivalent to that of a \hat{LG} = U(1) |x LG bundle over the base of the
circle bundle. We apply this to the Kaluza-Klein reduction of M-theory to IIA
and show that certain generalized characteristic classes of the loop group
bundle encode the Bianchi identities of the antisymmetric tensor fields of IIA
supergravity. We further show that the low dimensional characteristic classes
of the central extension of the loop group encode the Bianchi identities of
massive IIA, thereby adding support to the conjectures of hep-th/0203218.Comment: 26 pages, LaTeX, utarticle.cls, v2:clarifications and refs adde
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