6,201 research outputs found
Multiferroic Quantum Criticality
The zero-temperature limit of a continuous phase transition is marked by a
quantum critical point, which can generate exotic physics that extends to
elevated temperatures. Magnetic quantum criticality is now well known, and has
been explored in systems ranging from heavy fermion metals to quantum Ising
materials. Ferroelectric quantum critical behaviour has also been recently
established, motivating a flurry of research investigating its consequences.
Here, we introduce the concept of multiferroic quantum criticality, in which
both magnetic and ferroelectric quantum criticality occur in the same system.
We develop the phenomenology of multiferroic quantum critical behaviour,
describe the associated experimental signatures, and propose material systems
and schemes to realize it.Comment: 8 pages, 4 figure
Generalized Parton Distributions of ^3He
A realistic microscopic calculation of the unpolarized quark Generalized
Parton Distribution (GPD) of the nucleus is presented. In
Impulse Approximation, is obtained as a convolution between the GPD of
the internal nucleon and the non-diagonal spectral function, describing
properly Fermi motion and binding effects. The proposed scheme is valid at low
values of , the momentum transfer to the target, the most relevant
kinematical region for the coherent channel of hard exclusive processes. The
obtained formula has the correct forward limit, corresponding to the standard
deep inelastic nuclear parton distributions, and first moment, giving the
charge form factor of . Nuclear effects, evaluated by a modern realistic
potential, are found to be larger than in the forward case. In particular, they
increase with increasing the momentum transfer when the asymmetry of the
process is kept fixed, and they increase with the asymmetry at fixed momentum
transfer. Another relevant feature of the obtained results is that the nuclear
GPD cannot be factorized into a -dependent and a
-independent term, as suggested in prescriptions proposed for finite
nuclei. The size of nuclear effects reaches 8 % even in the most important part
of the kinematical range under scrutiny. The relevance of the obtained results
to study the feasibility of experiments is addressed.Comment: 23 pages, 8 figures; Discussion in section II enlarged; discussion in
section IV shortened. Final version accepted by Phys. Rev.
High Pressure optical nanothermometer based on Er3+ photoluminescence
The optical properties of a sparsely investigated material, LaGdO3 doped with Er3+, are explored regarding its suitability as nanothermometer. Besides its excellent capabilities for dielectric applications, when doping with Er3+, this material provides a highly efficient upconversion photoluminescence (PL) for high temperature thermometry at high pressure due to its structural stability. LaGdO3 belongs to the perovskite-type ABO3 compounds with a B-type monoclinic C2/m space group (a = 14.43 Å; b = 3.69 Å; c = 9.00 Å; and ? = 100.70º) at ambient conditions. It undergoes a structural phase transition to a hexagonal ?3#?1 phase at 3GPa yielding a notable PL enhancement, thus enabling it as a potential high-pressure hightemperature nanothermometer.We acknowledge financial support from MAT2015-69508-P (MINECO/FEDER), MAT2015-71070-REDC; PGC2018-101464-B-I00 (MICIN/FEDER), IDIVAL 18/28, the European Research Council FET-OPEN NCLas H2020 Project (EU829161), and BSH Electrodomésticos España, S.A
Osteomielitis vertebral cervical como complicación de cirugía faríngea: a propósito de un caso
Se presenta un caso de un a enferma de 59 años, diabética, afecta de un a
osteomielitis vertebral cervical por Candida Albicans. La vía de infección fué la persistencia
durante varios meses de unos tutores, colocados tras la resección de un a estenosis nasofaríngea ,
que impactaban sobre la cara anterior de la vértebra C3. El desarrollo insidioso y la ausencia
de un cuadro clínico específico fué la causa del retraso diagnóstico.A 5 9 yea r ol d woma n wit h diabete s mellitu s presente d a cervica l
vertebra l osteomyelitis du e t o Candid a Albicans. Th e chroni c implantatio n o f dilatio
n tube s followin g th e resectio n o f a nasopharyngea l stenosis wa s th e mod e o f
infection . Th e insidiou s an d prolonge d onse t an d n o specifica l clinica l pictur e wer e
t h e caus e o f dela y i n th e diagnosi
Infinite-layer fluoro-nickelates as model materials
We study theoretically the fluoro-nickelate series NiF ( Li, Na,
K, Rb, Cs) in the tetragonal infinite-layer structure. We use density
functional theory to determine the structural parameters and the electronic
band structure of these unprecedented compounds. Thus, we predict these
materials as model systems where the Ni oxidation is realized and
the low-energy physics is completely determined by the Ni-3 bands only.
Fluoro-nickelates of this class thus offer an ideal platform for the study of
intriguing physics that emerges out of the special electronic
configuration, notably high-temperature unconventional superconductivity.Comment: 6 pages, 4 tables, and 6 figure
Low-temperature specific heat of real crystals: Possibility of leading contribution of optical and short-wavelength acoustical vibrations
We point out that the repeatedly reported glass-like properties of
crystalline materials are not necessarily associated with localized (or
quasilocalized) excitations. In real crystals, optical and short-wavelength
acoustical vibrations remain damped due to defects down to zero temperature. If
such a damping is frequency-independent, e.g. due to planar defects or charged
defects, these optical and short-wavelength acoustical vibrations yield a
linear-in- contribution to the low-temperature specific heat of the crystal
lattices. At low enough temperatures such a contribution will prevail over that
of the long-wavelength acoustical vibrations (Debye contribution). The
crossover between the linear and the Debye regime takes place at , where is the concentration of the defects responsible for the
damping. Estimates show that this crossover could be observable.Comment: 5 pages. v4: Error in Appendix corrected, which does not change the
main results of the pape
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A pragmatic patient-reported outcome strategy for rare disease clinical trials: application of the EORTC item library to myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia.
BackgroundNovel, pragmatic, patient-centered strategies are needed to ensure fit-for-purpose patient-reported outcomes (PRO) instruments in clinical trial research for rare diseases such as myelodysplastic syndromes (MDS), acute myeloid leukemia (AML), and chronic myelomonocytic leukemia (CMML). The objective of the current study was to select supplemental items to add to the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life-Core 30 (QLQ-C30) to ensure content coverage of all important clinical concepts in patients with higher-risk (HR) MDS, low-blast count (LB) AML, and CMML, thus, improving the instrument's ability to detect clinically meaningful treatment benefit for this context of use.MethodsOur mixed methods approach comprised literature review, clinician consultation (n = 3), and qualitative and quantitative analysis of two stages of patient interview data (n = 14, n = 18) to select library bank items to supplement a generic cancer PRO, the EORTC QLQ-C30.ResultsUnique symptom (n = 54) and impact (n = 72) concepts were organized into conceptual frameworks of treatment benefit, compared with EORTC QLQ-C30 items and conceptual gaps identified. Supplemental items (n = 13) addressing those gaps were selected from the EORTC Item Library and tested with patients. Supplemental item endorsement frequencies met World Health Organization Quality of Life criteria, suggesting good targeting and relevance for this sample. However, three supplemental items were confirmed as problematic based upon cognitive debriefing results, and expert clinical consultations. Ultimately, 10 supplemental items (n = 7 symptom; n = 3 impact) were selected for the MDS/AML/CMML context.ConclusionSupplemental items were selected to enhance the conceptual coverage of the EORTC QLQ-C30 in the areas of fatigue, shortness of breath, and functioning
Electromagnon excitations in modulated multiferroics
The phenomenological theory of ferroelectricity in spiral magnets presented
in [M. Mostovoy, Phys. Rev. Lett. 96, 067601 (2006)] is generalized to describe
consistently states with both uniform and modulated-in-space ferroelectric
polarizations. A key point in this description is the symmetric part of the
magnetoelectric coupling since, although being irrelevant for the uniform
component, it plays an essential role for the non-uniform part of the
polarization. We illustrate this importance in generic examples of modulated
magnetic systems: longitudinal and transverse spin-density wave states and
planar cycloidal phase. We show that even in the cases with no uniform
ferroelectricity induced, polarization correlation functions follow to the soft
magnetic behavior of the system due to the magnetoelectric effect. Our results
can be easily generalized for more complicated types of magnetic ordering, and
the applications may concern various natural and artificial systems in
condensed matter physics (e.g., magnon properties could be extracted from
dynamic dielectric response measurements).Comment: 5 page
The optical identifcation of events with poorly defined locations: The case of the Fermi GBM GRB140801A
We report the early discovery of the optical afterglow of gamma-ray burst
(GRB) 140801A in the 137 deg 3- error-box of the Fermi Gamma-ray
Burst Monitor (GBM). MASTER is the only observatory that automatically react to
all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart
was discovered solely from its GBM localization. The optical afterglow of GRB
140801A was found by MASTER Global Robotic Net 53 sec after receiving the
alert, making it the fastest optical detection of a GRB from a GBM error-box.
Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m BTA
of SAO RAS reveals a redshift of . We performed optical and
near-infrared photometry of GRB 140801A using different telescopes with
apertures ranging from 0.4-m to 10.4-m. GRB 140801A is a typical burst in many
ways. The rest-frame bolometric isotropic energy release and peak energy of the
burst is erg and
keV, respectively, which is consistent with the
Amati relation. The absence of a jet break in the optical light curve provides
a lower limit on the half-opening angle of the jet deg. The
observed is consistent with the limit derived from the
Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis shows that GRB
140801A could belong to the class of intermediate duration. The rapid detection
of the optical counterpart of GRB 140801A is especially important regarding the
upcoming experiments with large coordinate error-box areas.Comment: in press MNRAS, 201
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