Using the Nonlinear Duffing Effect of Piezoelectric Micro-Oscillators for Wide-Range Pressure Sensing

This paper investigates the resonant behaviour of silicon-based micro-oscillators with a length of 3600 µm, a width of 1800 µm and a thickness of 10 µm over a wide range of ambient gas (N2 ) pressures, extending over six orders of magnitude from 10−3 mbar to 900 mbar. The oscillators are actuated piezoelectrically by a thin-film aluminium-nitride (AlN) layer, with the cantilever coverage area being varied from 33% up to 100%. The central focus is on nonlinear Duffing effects, occurring at higher oscillation amplitudes. A theoretical background is provided. All relevant parameters describing a Duffing oscillator, such as stiffness parameters for each coverage size as well as for different bending modes and more complex modes, are extracted from the experimental data. The so-called 2nd roof-tile-shaped mode showed the highest stiffness value of −97.3·107 m−2 s −2 . Thus, it was chosen as being optimal for extended range pressure measurements. Interestingly, both a spring softening effect and a spring hardening effect were observed in this mode, depending on the percentage of the AlN coverage area. The Duffing-effect-induced frequency shift was found to be optimal for obtaining the highest pressure sensitivity, while the size of the hysteresis loop is also a very useful parameter because of the possibility of eliminating the temperature influences and long-term drift effects of the resonance frequency. An reasonable application-specific compromise between the sensitivity and the measurement range can be selected by adjusting the excitation voltage, offering much flexibility. This novel approach turns out to be very promising for compact, cost-effective, wide-range pressure measurements in the vacuum range

Mitochondrial d-loop variation, coat colour and sex identification of Late Iron Age horses in Switzerland

In the Celtic world, horses enjoyed a prominent position as status symbols and objects of veneration, yet little is known about these Celtic horses except that they were rather small. The Late Iron Age was a time defined by increasing inter-cultural contact between Celtic peoples and the Romans. This is, amongst other features, observable in the phenotypes of domestic livestock such as horses. Amongst the usually small animals, larger ones are rarely but regularly encountered in the archaeological record. We have investigated mitochondrial (mt) DNA d-loop diversity, sex and coat colour using bones from 34 horses of different size from three Swiss sites (Mormont, Basel-Gasfabrik, Aventicum) most of them dating from 150 to 50 BCE. The aim was to characterise the diversity of matrilineages and coat colourations of Iron Age horses, and to identify molecular sex. We detected eleven mt haplotypes clustering into six haplogroups (B, D, F, I, X2, X3) in the ancient dataset (n = 19). Large individuals were all male, but smaller stallions were also identified; molecular sexing confirmed and augmented to morphological results. The horses were bay, chestnut and black in colour, and spottings or dilutions were absent in all animals. With a simplified primer system to detect premature greying, white coats can be excluded as well. The limited colour range proposes selection for monochrome animals. Additionally, ancient matrilineages were compared to modern horses from regions appertaining to the Late Roman Republic and to European pony breeds. Based on Principal Component Analysis (haplotype frequencies) and FST-values (genetic distances) the mtDNA variation of the Iron Age horses investigated here has survived in modern European breeds, particularly in northern European ponies

Plan your trip before you leave: The neutrophils’ search-and-run journey

Reading, interpreting and crawling along gradients of chemotactic cues is one of the most complex questions in cell biology. In this issue, Georgantzoglou et al. (2022. J. Cell. Biol.https://doi.org/10.1083/jcb.202103207) use in vivo models to map the temporal sequence of how neutrophils respond to an acutely arising gradient of chemoattractant

Graph theory analysis of cortical thickness networks in adolescents with d‐transposition of the great arteries

Abstract Objective: Adolescents with d‐transposition of the great arteries (d‐TGA) who had the arterial switch operation in infancy have been found to have structural brain differences compared to healthy controls. We used cortical thickness measurements obtained from structural brain MRI to determine group differences in global brain organization using a graph theoretical approach. Methods: Ninety‐two d‐TGA subjects and 49 controls were scanned using one of two identical 1.5‐Tesla MRI systems. Mean cortical thickness was obtained from 34 regions per hemisphere using Freesurfer. A linear model was used for each brain region to adjust for subject age, sex, and scanning location. Structural connectivity for each group was inferred based on the presence of high inter‐regional correlations of the linear model residuals, and binary connectivity matrices were created by thresholding over a range of correlation values for each group. Graph theory analysis was performed using packages in R. Permutation tests were performed to determine significance of between‐group differences in global network measures. Results: Within‐group connectivity patterns were qualitatively different between groups. At lower network densities, controls had significantly more long‐range connections. The location and number of hub regions differed between groups: controls had a greater number of hubs at most network densities. The control network had a significant rightward asymmetry compared to the d‐TGA group at all network densities. Conclusions: Using graph theory analysis of cortical thickness correlations, we found differences in brain structural network organization among d‐TGA adolescents compared to controls. These may be related to the white matter and gray matter differences previously found in this cohort, and in turn may be related to the cognitive deficits this cohort presents

Pregnancy after bariatric surgery: a narrative literature review and discussion of impact on pregnancy management and outcome

Abstract Bariatric surgery (BS) is regarded to be the most effective treatment of obesity with long lasting beneficial effects including weight loss and improvement of metabolic disorders. A considerable number of women undergoing BS are at childbearing age. Although the surgery mediated weight loss has a positive effect on pregnancy outcome, the procedures might be associated with adverse outcomes as well, for example micronutrient deficiencies, iron or B12 deficiency anemia, dumping syndrome, surgical complications such as internal hernias, and small for gestational age (SGA) offspring, possibly due to maternal undernutrition. Also, there is no international consensus concerning the ideal time to conception after BS. Hence, the present narrative review intents to summarize the available literature concerning the most common challenges which arise before and during pregnancy after BS, such as fertility related considerations, vitamin and nutritional deficiencies and their adequate compensation through supplementation, altered glucose metabolism and its implications for gestational diabetes screening, the symptoms and treatment of dumping syndrome, surgical complications and the impact of BS on pregnancy outcome. The impact of different bariatric procedures on pregnancy and fetal outcome will also be discussed, as well as general considerations concerning the monitoring and management of pregnancies after BS. Whereas BS leads to the mitigation of many obesity-related pregnancy complications, such as gestational diabetes mellitus (GDM), pregnancy induced hypertension and fetal macrosomia; those procedures pose new risks which might lead to adverse outcomes for mothers and offspring, for example nutritional deficiencies, anemia, altered maternal glucose metabolism and small for gestational age children

CCR7 acts as both a sensor and a sink for CCL19 to coordinate collective leukocyte migration

Immune responses rely on the rapid and coordinated migration of leukocytes. Whereas it is well established that single-cell migration is often guided by gradients of chemokines and other chemoattractants, it remains poorly understood how these gradients are generated, maintained, and modulated. By combining experimental data with theory on leukocyte chemotaxis guided by the G protein–coupled receptor (GPCR) CCR7, we demonstrate that in addition to its role as the sensory receptor that steers migration, CCR7 also acts as a generator and a modulator of chemotactic gradients. Upon exposure to the CCR7 ligand CCL19, dendritic cells (DCs) effectively internalize the receptor and ligand as part of the canonical GPCR desensitization response. We show that CCR7 internalization also acts as an effective sink for the chemoattractant, dynamically shaping the spatiotemporal distribution of the chemokine. This mechanism drives complex collective migration patterns, enabling DCs to create or sharpen chemotactic gradients. We further show that these self-generated gradients can sustain the long-range guidance of DCs, adapt collective migration patterns to the size and geometry of the environment, and provide a guidance cue for other comigrating cells. Such a dual role of CCR7 as a GPCR that both senses and consumes its ligand can thus provide a novel mode of cellular self-organization