106 research outputs found
Perspectives on high-frequency nanomechanics, nanoacoustics, and nanophononics
Nanomechanics, nanoacoustics, and nanophononics refer to the engineering of
acoustic phonons and elastic waves at the nanoscale and their interactions with
other excitations such as magnons, electrons, and photons. This engineering
enables the manipulation and control of solid-state properties that depend on
the relative positions of atoms in a lattice. The access to advanced
nanofabrication and novel characterization techniques enabled a fast
development of the fields over the last decade. The applications of
nanophononics include thermal management, ultrafast data processing,
simulation, sensing, and the development of quantum technologies. In this
review, we cover some of the milestones and breakthroughs, and identify
promising pathways of these emerging fields.Comment: 19 pages, 3 figure
Topological acoustics in coupled nanocavity arrays
The Su-Schrieffer-Heeger (SSH) model is likely the simplest one-dimensional
concept to study non-trivial topological phases and topological excitations.
Originally developed to explain the electric conductivity of polyacetylene, it
has become a platform for the study of topological effects in electronics,
photonics and ultra-cold atomic systems. Here, we propose an experimentally
feasible implementation of the SSH model based on coupled one-dimensional
acoustic nanoresonators working in the GHz-THz range. In this simulator it is
possible to implement different signs in the nearest neighbor interaction
terms, showing full tunability of all parameters in the SSH model. Based on
this concept we construct topological transition points generating nanophononic
edge and interface states and propose an easy scheme to experimentally probe
their spatial complex amplitude distribution directly by well-established
optical pump-probe techniques.Comment: 10 pages, 4 figure
A virtual reality exposure therapy for PTSD patients controlled by a fuzzy logic system
This paper describes the main characteristics of two integrated systems that explore Virtual Reality technology and Fuzzy Logic to support and to control the assessment of people with Post-Traumatic Stress Disorder during the Virtual Reality Exposure Therapy. The integration of different technologies, the development methodology and the test procedures are described throughout the paper.Peer Reviewe
Towards chiral acoustoplasmonics
The possibility of creating and manipulating nanostructured materials
encouraged the exploration of new strategies to control electromagnetic
properties. Among the most intriguing nanostructures are those that respond
differently to helical polarization, i.e., exhibit chirality. Here, we present
a simple structure based on crossed elongated bars where light-handedness
defines the dominating cross-section absorption or scattering, with a 200%
difference from its counterpart (scattering or absorption). The proposed chiral
system opens the way to enhanced coherent phonon excitation and detection. We
theoretically propose a simple pump-probe experiment using circularly polarized
light. In the reported structures, the generation of acoustic phonons is
optimized by maximizing the absorption, while the detection is enhanced at the
same wavelength -- and different helicity -- by engineering the scattering
properties. The presented results constitute one of the first steps towards
harvesting chirality effects in the design and optimization of efficient and
versatile acoustoplasmonic transducers.Comment: 10 pages, 6 figure
Brillouin Scattering in Hybrid Optophononic Bragg Micropillar Resonators at 300 GHz
We introduce a monolithic Brillouin generator based on a semiconductor
micropillar cavity embedding a high frequency nanoacoustic resonator operating
in the hundreds of GHz range. The concept of two nested resonators allows an
independent design of the ultrahigh frequency Brillouin spectrum and of the
optical device. We develop an optical free-space technique to characterize
spontaneous Brillouin scattering in this monolithic device and propose a
measurement protocol that maximizes the Brillouin generation efficiency in the
presence of optically induced thermal effects. The compact and versatile
Brillouin generator studied here could be readily integrated into fibered and
on-chip architectures.Comment: 9 pages, 4 figure
Multifractal analysis of the electronic states in the Fibonacci superlattice under weak electric fields
Influence of the weak electric field on the electronic structure of the
Fibonacci superlattice is considered. The electric field produces a nonlinear
dynamics of the energy spectrum of the aperiodic superlattice. Mechanism of the
nonlinearity is explained in terms of energy levels anticrossings. The
multifractal formalism is applied to investigate the effect of weak electric
field on the statistical properties of electronic eigenfunctions. It is shown
that the applied electric field does not remove the multifractal character of
the electronic eigenfunctions, and that the singularity spectrum remains
non-parabolic, however with a modified shape. Changes of the distances between
energy levels of neighbouring eigenstates lead to the changes of the inverse
participation ratio of the corresponding eigenfunctions in the weak electric
field. It is demonstrated, that the local minima of the inverse participation
ratio in the vicinity of the anticrossings correspond to discontinuity of the
first derivative of the difference between marginal values of the singularity
strength. Analysis of the generalized dimension as a function of the electric
field shows that the electric field correlates spatial fluctuations of the
neighbouring electronic eigenfunction amplitudes in the vicinity of
anticrossings, and the nonlinear character of the scaling exponent confirms
multifractality of the corresponding electronic eigenfunctions.Comment: 10 pages, 9 figure
The 10 kDa domain of human erythrocyte protein 4.1 binds the Plasmodium falciparum EBA-181 protein
BACKGROUND: Erythrocyte invasion by Plasmodium falciparum parasites represents a key mechanism during malaria pathogenesis. Erythrocyte binding antigen-181 (EBA-181) is an important invasion protein, which mediates a unique host cell entry pathway. A novel interaction between EBA-181 and human erythrocyte membrane protein 4.1 (4.1R) was recently demonstrated using phage display technology. In the current study, recombinant proteins were utilized to define and characterize the precise molecular interaction between the two proteins. METHODS: 4.1R structural domains (30, 16, 10 and 22 kDa domain) and the 4.1R binding region in EBA-181 were synthesized in specific Escherichia coli strains as recombinant proteins and purified using magnetic bead technology. Recombinant proteins were subsequently used in blot-overlay and histidine pull-down assays to determine the binding domain in 4.1R. RESULTS: Blot overlay and histidine pull-down experiments revealed specific interaction between the 10 kDa domain of 4.1R and EBA-181. Binding was concentration dependent as well as saturable and was abolished by heat denaturation of 4.1R. CONCLUSION: The interaction of EBA-181 with the highly conserved 10 kDa domain of 4.1R provides new insight into the molecular mechanisms utilized by P. falciparum during erythrocyte entry. The results highlight the potential multifunctional role of malaria invasion proteins, which may contribute to the success of the pathogenic stage of the parasite's life cycle
Incidence of local complications and risk factors associated with peripheral intravenous catheter in neonates
Abstract OBJECTIVE To evaluate the incidence of complications related to the use of peripheral intravenous catheter in neonates and identify the associated risk factors. METHOD Prospective cohort study conducted in a Neonatal Intensive Care Unit. Participants were the hospitalized neonates undergoing peripheral intravenous puncture in the period from February to June 2013. RESULTS The incidence of complications was 63.15%, being infiltration/extravasation (69.89%), phlebitis (17.84%) and obstruction (12.27%). The risk factors were the presence of infection (p = 0.0192) and weight at the puncture day (p = 0.0093), type of intermittent infusion associated with continuous infusion (p <0.0001), endotracheal intubation (p = 0.0008), infusion of basic plan (p = 0.0027), total parenteral nutrition (P = 0.0002), blood transfusion associated with other infusions (p = 0.0003) and other drugs (p = 0.0004). Higher risk of developing complications in the first 48 hours after puncture. CONCLUSION A high rate of complications related to the use of peripheral intravenous catheter, and risk factors associated with infection, weight, drugs and infused solutions, and type of infusion
Nursing Care of Patients With Cirrhosis: The LiverHope Nursing Project
Cirrhosis is a complex disease that is associated with disturbances in different organs besides the liver, including kidneys, heart, arterial circulation, lungs, gut, and brain. As a consequence, patients develop a number of complications that result in frequent hospital admissions and high morbidity and mortality. Patients with cirrhosis require constant and rigorous monitoring both in and outside the hospital. In this context, the role of nurses in the care of patients with cirrhosis has not been sufficiently emphasized and there is very limited information about nursing care of patients with cirrhosis compared with other chronic diseases. The current article provides a review of nursing care for the different complications of patients with cirrhosis. Nurses with specific knowledge on liver diseases should be incorporated into multidisciplinary teams managing patients with cirrhosis, both inpatient and outpatient. Conclusion: Nurses play an important role in the management and prevention of complications of the disease and improvement in patients’ quality of life and bridge the gap between clinicians and families, between primary care and hospital care, and provide medical education to patients and caregivers
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