Detecting Abrupt Changes in the Presence of Local Fluctuations and Autocorrelated Noise

The current miniaturization trend in the market of inertial microsystems is leading to movable device parts with sizes comparable to the characteristic length-scale of the polycrystalline silicon film morphology. The relevant output of micro electro-mechanical systems (MEMS) is thus more and more affected by a scattering, induced by features resulting from the micro-fabrication process. We recently proposed an on-chip testing device, specifically designed to enhance the aforementioned scattering in compliance with fabrication constraints. We proved that the experimentally measured scattering cannot be described by allowing only for the morphology-affected mechanical properties of the silicon films, and etch defects must be properly accounted for too. In this work, we discuss a fully stochastic framework allowing for the local fluctuations of the stiffness and of the etch-affected geometry of the silicon film. The provided semi-analytical solution is shown to catch efficiently the measured scattering in the C-V plots collected through the test structure. This approach opens up the possibility to learn on-line specific features of the devices, and to reduce the time required for their calibration.

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Model Based Assessment of the Reflection Behavior of Tidal Waves at Bathymetric Changes in Estuaries

Water ◽

10.3390/w13040489 ◽

2021 ◽

Vol 13 (4) ◽

pp. 489

Author(s):

Vanessa Sohrt ◽

Sebastian S.V. Hein ◽

Edgar Nehlsen ◽

Thomas Strotmann ◽

Peter Fröhle

Keyword(s):

Cross Sectional ◽

High Agreement ◽

Tidal Waves ◽

Level Data ◽

Water Level Data ◽

Abrupt Changes ◽

Water Effects ◽

Potential Impact ◽

Tidal Constituents ◽

Harmonic Components

Estuaries are often modified by human activities. Adjustments in the morphology of an estuary have a potential impact on the hydrodynamics and on the reflection behavior of the tide. The influence of such system changes on the complex tidal regime with a large number of superimposed tidal constituents is not fully understood yet. The reflection properties of estuaries that are characterized by abrupt changes in geometry are systematically investigated on the basis of simplified estuary model approaches to improve the understanding of the oscillation and reflection behavior of tidal waves in estuaries. The reflection coefficients at abrupt cross-sectional changes are determined by two different methods, i.e., an analytical energy-based approach and a hydrodynamic numerical (HN) model. Comparisons indicate a high agreement of the results of the different methods when evaluating the reflection coefficient. The tidal constituents are reflected at partial and total reflectors and amplified by shoaling depending on the water depths, the height of the bottom step and the horizontal constriction. A harmonic analysis of simulated water level data partly shows the formation and amplification of higher harmonic components as a result of shallow water effects. The interaction with reflectors results in an increasing amplification of the tidal constituents and the tide.

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Resilience, plasticity and robustness in gene expression during aging in the brain of outbred deer mice

BMC Genomics ◽

10.1186/s12864-021-07613-2 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

E Soltanmohammadi ◽

Y Zhang ◽

I Chatzistamou ◽

H. Kiaris

Keyword(s):

Gene Expression ◽

Cholesterol Metabolism ◽

Expression Profiles ◽

Deer Mice ◽

Abrupt Changes ◽

Transcriptional Changes ◽

Thrombospondin 4 ◽

Whole Transcriptome ◽

The Brain ◽

Shed Light

Abstract Background Genes that belong to the same network are frequently co-expressed, but collectively, how the coordination of the whole transcriptome is perturbed during aging remains unclear. To explore this, we calculated the correlation of each gene in the transcriptome with every other, in the brain of young and older outbred deer mice (P. leucopus and P. maniculatus). Results In about 25 % of the genes, coordination was inversed during aging. Gene Ontology analysis in both species, for the genes that exhibited inverse transcriptomic coordination during aging pointed to alterations in the perception of smell, a known impairment occurring during aging. In P. leucopus, alterations in genes related to cholesterol metabolism were also identified. Among the genes that exhibited the most pronounced inversion in their coordination profiles during aging was THBS4, that encodes for thrombospondin-4, a protein that was recently identified as rejuvenation factor in mice. Relatively to its breadth, abolishment of coordination was more prominent in the long-living P. leucopus than in P. maniculatus but in the latter, the intensity of de-coordination was higher. Conclusions There sults suggest that aging is associated with more stringent retention of expression profiles for some genes and more abrupt changes in others, while more subtle but widespread changes in gene expression appear protective. Our findings shed light in the mode of the transcriptional changes occurring in the brain during aging and suggest that strategies aiming to broader but more modest changes in gene expression may be preferrable to correct aging-associated deregulation in gene expression.

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The anatomy of past abrupt warmings recorded in Greenland ice

Nature Communications ◽

10.1038/s41467-021-22241-w ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

E. Capron ◽

S. O. Rasmussen ◽

T. J. Popp ◽

T. Erhardt ◽

H. Fischer ◽

...

Keyword(s):

Climate Changes ◽

Ice Core ◽

Ice Cores ◽

Climate System ◽

Data Availability ◽

Tight Coupling ◽

Decadal Scale ◽

Abrupt Changes ◽

Systematic Pattern ◽

The Last Glacial

AbstractData availability and temporal resolution make it challenging to unravel the anatomy (duration and temporal phasing) of the Last Glacial abrupt climate changes. Here, we address these limitations by investigating the anatomy of abrupt changes using sub-decadal-scale records from Greenland ice cores. We highlight the absence of a systematic pattern in the anatomy of abrupt changes as recorded in different ice parameters. This diversity in the sequence of changes seen in ice-core data is also observed in climate parameters derived from numerical simulations which exhibit self-sustained abrupt variability arising from internal atmosphere-ice-ocean interactions. Our analysis of two ice cores shows that the diversity of abrupt warming transitions represents variability inherent to the climate system and not archive-specific noise. Our results hint that during these abrupt events, it may not be possible to infer statistically-robust leads and lags between the different components of the climate system because of their tight coupling.

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