3,529 research outputs found
Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high-Tc superconductor
Charge density waves are a common occurrence in all families of high critical
temperature superconducting cuprates. Although consistently observed in the
underdoped region of the phase diagram and at relatively low temperatures, it
is still unclear to what extent they influence the unusual properties of these
systems. Using resonant x-ray scattering we carefully determined the
temperature dependence of charge density modulations in
(Y,Nd)BaCuO for three doping levels. We discovered
short-range dynamical charge density fluctuations besides the previously known
quasi-critical charge density waves. They persist up to well above the
pseudogap temperature T*, are characterized by energies of few meV and pervade
a large area of the phase diagram, so that they can play a key role in shaping
the peculiar normal-state properties of cuprates.Comment: 34 pages, 4 figures, 11 supplementary figure
Development of a Novel Snom Probe for in Liquid Biological Samples
This work is focused on the study and implementation of a novel method for the development of probes for Scanning Near-field Optical Microscopy (SNOM). The proposed approach is based on the mechanical impedance matching between the optical fiber tip and the resonating tuning fork. This methodology allowed an increase of the quality factor of the piezoelectric resonator used as atomic force transducer in the SNOM probe, thus increasing its overall sensitivity. This kind of probes are often used on biological soft samples in liquid. The presence of water medium has a strong dumping effect on probe sensitivity. Experimental validation of the proposed methodology showed an increase of robustness of SNOM probes also for in liquid samples
Reduction and reconstruction of stochastic differential equations via symmetries
An algorithmic method to exploit a general class of infinitesimal symmetries
for reducing stochastic differential equations is presented and a natural
definition of reconstruction, inspired by the classical reconstruction by
quadratures, is proposed. As a side result the well-known solution formula for
linear one-dimensional stochastic differential equations is obtained within
this symmetry approach. The complete procedure is applied to several examples
with both theoretical and applied relevance
The role of clothing in thermal comfort: how people dress in a temperate and humid climate in Brazil
Abstract Thermal insulation from clothing is one of the most important input variables used to predict the thermal comfort of a building's occupants. This paper investigates the clothing pattern in buildings with different configurations located in a temperate and humid climate in Brazil. Occupants of two kinds of buildings (three offices and two university classrooms) assessed their thermal environment through 'right-here-right-now' questionnaires, while at the same time indoor climatic measurements were carried out in situ (air temperature and radiant temperature, air speed and humidity). A total of 5,036 votes from 1,161 occupants were collected. Results suggest that the clothing values adopted by occupants inside buildings were influenced by: 1) climate and seasons of the year; 2) different configurations and indoor thermal conditions; and 3) occupants' age and gender. Significant intergenerational and gender differences were found, which might be explained by differences in metabolic rates and fashion. The results also indicate that there is a great opportunity to exceed the clothing interval of the thermal comfort zones proposed by international standards such as ASHRAE 55 (2013) - 0.5 to 1.0 clo - and thereby save energy from cooling and heating systems, without compromising the occupants' indoor thermal comfort
Exploring multielement nanogranular coatings to forestall implant-related infections
Introduction: As we approach the post-antibiotic era, the development of innovative
antimicrobial strategies that carry out their activities through non-specific mechanisms
could limit the onset and spread of drug resistance. In this context, the use of
nanogranular coatings of multielement nanoparticles (NPs) conjugated to the surface
of implantable biomaterialsmight represent a strategy to reduce the systemicdrawbacks
by locally confining the NPs effects against either prokaryotic or eukaryotic cells.
Methods: In the present study, two new multielement nanogranular coatings
combining Ag and Cu with either Ti or Mg were synthesized by a gas phase physical
method and tested against pathogens isolated from periprosthetic joint infections to
address their potential antimicrobial value and toxicity in an in vitro experimental setting.
Results: Overall, Staphylococcus aureus, Staphylococcus epidermidis and
Escherichia coli displayed a significantly decreased adhesion when cultured on
Ti-Ag-Cu and Mg-Ag-Cu coatings compared to uncoated controls, regardless of
their antibiotic resistance traits. A dissimilar behavior was observed when
Pseudomonas aeruginosa was cultured for 30 and 120 minutes upon the surface
of Ti-Ag-Cu and Mg-Ag-Cu-coated discs. Biofilm formation was mainly reduced
by the active effect of Mg-Ag-Cu compared to Ti-Ag-Cu and, again, coatings had a
milder effect on P. aeruginosa, probably due to its exceptional capability of
attachment and matrix production. These data were further confirmed by the
evaluation of bacterial colonization on nanoparticle-coated discs through
confocal microscopy. Finally, to exclude any cytotoxic effects on eukaryotic
cells, the biocompatibility of NPs-coated discs was studied. Results
demonstrated a viability of 95.8% and 89.4% of cells cultured in the presence of
Ti-Ag-Cu and Mg-Ag-Cu discs, respectively, when compared to negative controls.
Conclusion: In conclusion, the present study demonstrated the promising antiadhesive
features of both Ti-Ag-Cu and Mg-Ag-Cu coatings, as well as their action
in hampering the biofilm formation, highlighting the safe use of the tested multielement
families of nanoparticles as new strategies against bacterial attachment to
the surface of biomedical implants
Gait abnormalities in people with Dravet syndrome: A cross-sectional multi-center study
Objective: To quantify gait abnormalities in people with Dravet syndrome (DS). Methods: Individuals with a confirmed diagnosis of DS were enrolled, and stratified according to knee flexion at initial contact (IC) and range of motion (ROM) during stance (atypical crouch: knee flexion >20\ub0 at IC and knee ROM >15\ub0 during stance; straight: knee flexion <20\ub0 at IC). A 1D ANOVA (\u3b1 = 0.05) was used to test statistical differences among the joint kinematics and spatio\u2013temporal parameters of the cohort and an age-matched control group. Clinical (neurological and orthopaedic evaluation) and anamnestic data (seizure type, drugs, genetic mutation) were collected; distribution between the two gait phenotypes was assessed with the Fisher exact test and, for mutation, with the chi-squared test (p < 0.05). Linear regression between maximum knee flexion and normalised walking speed was calculated. Results: Seventy-one subjects were enrolled and evaluated with instrumented gait analysis. Fifty-two were included in final analysis (mean age 13.8 \ub1 7.3; M 26). Two gait patterns were detected: an atypical crouch gait (34.6%) with increased ankle, knee and hip flexion during stance, and reduced walking speed and stride length not associated with muscle-tendon retractions; and a pattern resembling those of healthy age-matched controls, but still showing reduced walking speed and stride length. No differences in clinical or anamnestic data emerged between the two groups. Significance: Objectively quantified gait in DS shows two gait patterns with no clear-cut relation to clinical data. Kinematics abnormalities may be related to stabilization issues. These findings may guide rehabilitative and preventive measures
Performance of the LHCb muon system
The performance of the LHCb Muon system and its stability across the full
2010 data taking with LHC running at ps = 7 TeV energy is studied. The
optimization of the detector setting and the time calibration performed with
the first collisions delivered by LHC is described. Particle rates, measured
for the wide range of luminosities and beam operation conditions experienced
during the run, are compared with the values expected from simulation. The
space and time alignment of the detectors, chamber efficiency, time resolution
and cluster size are evaluated. The detector performance is found to be as
expected from specifications or better. Notably the overall efficiency is well
above the design requirementsComment: JINST_015P_1112 201
Cosmic evolution of FRI and FRII sources out to z=2.5
Radio-loud active galactic nuclei (RLAGN) play an important role in the
evolution of galaxies through the effects on their environment. The two major
morphological classes are core-bright (FRI) and edge-bright (FRII) sources.
With the LOw-Frequency ARray (LOFAR) we compare the FRI and FRII evolution down
to lower flux densities and with larger samples than before with the aim to
examine the cosmic space density evolution for FRIs and FRIIs by analyzing
their space density evolution between L_150~10^24.5 W/Hz and L_150~10^28.5 W/Hz
and up to z=2.5. We construct radio luminosity functions (RLFs) from FRI and
FRII catalogues based on recent data from LOFAR at 150MHz to study the space
densities as a function of radio luminosity and redshift. To partly correct for
selection biases and completeness, we simulate how sources appear at a range of
redshifts. We report a space density enhancement from low to high redshift for
FRI and FRII sources brighter than L_150~10^27 W/Hz. This is possibly related
to the higher gas availability in the earlier denser universe. The constant
FRI/FRII space density ratio evolution as a function of radio luminosity and
redshift in our results suggests that the jet-disruption of FRIs might be
primarily caused by events occurring on scales within the host galaxy, rather
than being driven by changes in the overall large-scale environment. Remaining
selection biases in our results also highlight the need to resolve more sources
at angular scales below 40 arcsec and therefore strengthens the motivation for
the further development and automation of the calibration and imaging pipeline
of LOFAR data to produce images at sub-arcsecond resolution
Performance of the Muon Identification at LHCb
The performance of the muon identification in LHCb is extracted from data
using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and
D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on
the pattern of hits in the muon chambers. A momentum dependent binary
requirement is used to reduce the probability of hadrons to be misidentified as
muons to the level of 1%, keeping the muon efficiency in the range of 95-98%.
As further refinement, a likelihood is built for the muon and non-muon
hypotheses. Adding a requirement on this likelihood that provides a total muon
efficiency at the level of 93%, the hadron misidentification rates are below
0.6%.Comment: 17 pages, 10 figure
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