93 research outputs found
Evolution of Complexity in Out-of-Equilibrium Systems by Time-Resolved or Space-Resolved Synchrotron Radiation Techniques
Out-of-equilibrium phenomena are attracting high interest in physics,
materials science, chemistry and life sciences. In this state, the study of
structural fluctuations at different length scales in time and space are
necessary to achieve significant advances in the understanding of
structure-functionality relationship. The visualization of patterns arising
from spatiotemporal fluctuations is nowadays possible thanks to new advances in
X-ray instrumentation development that combine high resolution both in space
and in time. We present novel experimental approaches using high brilliance
synchrotron radiation sources, fast detectors and focusing optics, joint with
advanced data analysis based on automated statistical, mathematical and imaging
processing tools. This approach has been used to investigate structural
fluctuations in out-of-equilibrium systems in the novel field of inhomogeneous
quantum complex matter at the crossing point of technology, physics and
biology. In particular, we discuss how nanoscale complexity controls the
emergence of high temperature superconductivity (HTS), myelin functionality and
formation of hybrid organic-inorganic nanostructures. The emergent complex
geometries, opening novel venues to quantum technology and to development of
quantum physics of living systems, are discussedComment: 18 pages, 7 figure
Correlated disorder in myelinated axons orientational geometry and structure
While the ultrastructure of the myelin has been considered to be a
quasi-crystalline stable system, nowadays its multiscale complex dynamics
appears to play a key role for its functionality, degeneration and repair
processes following neurological diseases and trauma. In this work, we have
investigated the axons interactions associated to the nerve functionality,
measuring the spatial distribution of the orientational fluctuations of axons
in a Xenopus Laevis sciatic nerve. At this aim, we have used Scanning micro
X-ray Diffraction (SmXRD), a non-invasive already applied to other
heterogeneous systems presenting complex geometries from microscale to
nanoscale. We have found that the orientational spatial fluctuations of fresh
axons show a correlated disorder described by Levy flight distribution. Thus,
we have studied how this correlated disorder evolves during the degeneration of
the nerve. Our results show that the spatial distribution of axons
orientational fluctuations in unfresh, aged nerve loose the correlated disorder
assuming a randomly disordered behaviour. This work allows a deeper
understanding of nerve states and paves the way to study other materials and
biomaterials with the same technique to detect and to characterize their states
and supramolecular structure, associated with dynamic structural changes at the
nanoscale and mesoscale.Comment: 9 pages, 4 figure
Efficiency of Covid-19 Mobile Contact Tracing Containment by Measuring Time Dependent Doubling Time
The Covid-19 epidemic of the novel coronavirus (severe acute respiratory
syndrome SARS - CoV-2) has been spreading around the world. While different
containment policies using non-pharmaceutical interventions have been applied,
their efficiency are not known quantitatively. We show that the doubling time
Td(t) with the success s factor, the characteristic time of the exponential
growth of Td(t) in the arrested regime, is a reliable tool for early
predictions of epidemic spread time evolution and it provides a quantitative
measure of the success of different containment measures. The efficiency of the
containment policy Lockdown case Finding mobile Tracing (LFT) using mandatory
mobile contact tracing is much higher than the Lockdown Stop and Go (LSG)
policy proposed by the Imperial College team in London. A very low s factor was
reached by LFT policy giving the shortest time width of the dome of positive
case curve and the lowest number of fatalities. The LFT policy has been able to
reduce by a factor 100 the number of fatalities in the first 100 days of the
Covid-19 epidemic, to reduce the time width of the Covid-19 pandemic dome by a
factor 2.5 and to rapidly stop new outbreaks avoiding the second waveComment: 20 pages, 4 figures, 2 tabl
Sars-Cov2 world pandemic recurrent waves controlled by variants evolution and vaccination campaign
While understanding the time evolution of Covid-19 pandemic is needed to plan economics and tune sanitary policies, a quantitative information of the recurrent epidemic waves is elusive. This work describes a statistical physics study of the subsequent waves in the epidemic spreading of Covid-19 and disclose the frequency components of the epidemic waves pattern over two years in United States, United Kingdom and Japan. These countries have been taken as representative cases of different containment policies such as "Mitigation" (USA and UK) and "Zero Covid" (Japan) policies. The supercritical phases in spreading have been identified by intervals with RIC-index> 0. We have used the wavelet transform of infection and fatality waves to get the spectral analysis showing a dominant component around 130 days. Data of the world dynamic clearly indicates also the crossover to a different phase due to the enforcement of vaccination campaign. In Japan and United Kingdom, we observed the emergence in the infection waves of a long period component (similar to 170 days) during vaccination campaign. These results indicate slowing down of the epidemic spreading dynamics due to the vaccination campaign. Finally, we find an intrinsic difference between infection and fatality waves pointing to a non-trivial variation of the lethality due to different gene variants
Scale free distribution of oxygen interstitials wires in optimum doped HgBaCuO
Novel nanoscale probes are opening new venues for understanding
unconventional electronic and magnetic functionalities driven by multiscale
lattice complexity in doped high temperature superconducting perovskites. In
this work we focus on the multiscale texture at supramolecular level of atomic
oxygen interstitials (O-i) stripes in HgBaCuO at optimal doping for
the highest superconducting critical temperature =94K. We report
compelling evidence for the nematic phase of oxygen-interstitial O-i atomic
wires with fractal-like spatial distribution over multiple scales by using
scanning micro and nano X-ray-diffraction. The scale free distribution of O-i
atomic wires at optimum doping extending from micron scale down to nanoscale
has been associated with the intricate filamentary network of hole rich
metallic wires in the CuO plane. The observed critical opalescence provides
evidence for the proximity to a critical point controlling the emergence of
high temperature superconductivity at optimum dopingComment: 16 pages, 3 figure
X-rays writing/reading of Charge Density Waves in the CuO2 plane of a simple cuprate superconductor
It is now well established that superconductivity in cuprates competes with
charge modulations giving electronic phase separation at a nanoscale. More
specifically, superconducting electronic current takes root in the available
free space left by electronic charge ordered domains, called charge density
wave (CDW) puddles. This means that CDW domain arrangement plays a fundamental
role in the mechanism of high temperature superconductivity in cuprates. Here
we report about the possibility of controlling the population and spatial
organization of the charge density wave puddles in a single crystal La2CuO4+y
through X - ray illumination and thermal treatments. We apply a pump - probe
method based on X - ray illumination as pump and X - ray diffraction as a probe
setting a writing and reading procedure of CDW puddles. Our findings are
expected to allow new routes for advanced design and manipulation of
superconducting pathways in new electronics.Comment: 11 Pages 4 figure
Epidemic spreading in an expanded parameter space: the supercritical scaling laws and subcritical metastable phases
So far most of the analysis of coronavirus 2020 epidemic data has been
focusing on a short-time window and consequently a quantitative test of
statistical physical laws of Coronavirus Epidemics with Containment Measures
(CEwCM) is currently lacking. Here we report a quantitative analysis of CEwCM
over 230 days, covering the full-time lapse of the first epidemic wave. We use
a 3D phase diagram tracking the simultaneous evolution of the doubling time
Td(t) and reproductive number Rt(t) showing that this expanded parameter space
is needed for biological physics of CEwCP. We have verified that in the
supercritical [Rt(t)>1, Td(t)<40 days] regime i) the curve Z(t) of total
infected cases follows the growth rate called Ostwald law; ii) the doubling
time follows the exponential law Td(t)=A exp((t-t0)/s) as a function of time
and iii) the power law Td(t)=C(Rt(t)-1)^-n is verified with the exponent n
depending on the definition of Rt(t). The log-log plots Td(t) versus (Rt-1) of
the second 2020 epidemic wave unveil in the subcritical regime [Td(t)>100 days]
arrested metastable phases with Rt>1 where Td(t) was kept constant followed by
its explosion and its containment following the same power law as in the first
waveComment: 15 pages, 4 figure
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