Search results for " isolation"

Early detection and classification of bearing faults using support vector machine algorithm

2017

Bearings are one of the most critical elements in rotating machinery systems. Bearing faults are the main reason for failures in electrical motors and generators. Therefore, early bearing fault detection is very important to prevent critical system failures in the industry. In this paper, the support vector machine algorithm is used for early detection and classification of bearing faults. Both time and frequency domain features are used for training the support vector machine learning algorithm. The trained classier can be employed for real-time bearing fault detection and classification. By using the proposed method, the bearing faults can be detected at early stages, and the machine oper…

Multiple low-frequency broad band gaps generated by a phononic crystal of periodic circular cavity sandwich plates

2017

Abstract We propose a new type of phononic crystal (PnC) composed of a periodic alternation of circular cavity sandwich plates. In the low-frequency regime, the crystal can modulate the propagation of flexural waves. Governing equations are deduced basing on the classical theory of coupled extensional and flexural vibrations of plates. The dispersion relation of the infinite PnC is calculated by combining the transfer matrix method with Bloch theory. The dynamic response of the PnC with finite unit cells is further studied with finite element analysis. An experiment is carried out to demonstrate the performance of the PnC in vibration isolation. Numerical results and experimental results bo…

Matrix isolation and quantum chemical studies on the H2O2–SO2complex

2004

Complexation and photochemical reactions of hydrogen peroxide and sulfur dioxide have been studied in solid Ar, Kr and Xe. Complexes between H2O2 and SO2 are characterized using Fourier transform infrared spectroscopy and ab initio calculations. In solid Ar, the H2O2–SO2 complex absorptions are found at wavenumbers of 3572.8, 3518.7, 3511.2, 3504.3, 1340.3, 1280.2 and 1149.9 cm−1. In Kr and Xe matrices, the bonded OH stretching frequencies deviate from the values in Ar, and we propose that the matrix surrounding influences the structure of the H2O2–SO2 complex. UV photolysis of the H2O2–SO2 was also studied in solid Ar, Kr and Xe. This photolysis produces mainly a complex between sulfur tri…

Isolating reactive metal-based species in Metal-Organic Frameworks - viable strategies and opportunities.

2021

Structural insight into reactive species can be achieved via strategies such as matrix isolation in frozen glasses, whereby species are kinetically trapped, or by confinement within the cavities of host molecules. More recently, Metal–Organic Frameworks (MOFs) have been used as molecular scaffolds to isolate reactive metal-based species within their ordered pore networks. These studies have uncovered new reactivity, allowed observation of novel metal-based complexes and clusters, and elucidated the nature of metal-centred reactions responsible for catalysis. This perspective considers strategies by which metal species can be introduced into MOFs and highlights some of the advantages and lim…

An experimental assessment of reproductive isolation and its consequences for seasonal hybridization dynamics

2018

Multiple mechanisms of cryptic female choice act on intraspecific male variation in Drosophila simulans

2016

Postcopulatory sexual selection can arise when females mate with multiple males and is usually mediated by an interaction between the sexes. Cryptic female choice (CFC) is one form of postcopulatory sexual selection that occurs when female morphology, physiology, or behavior generates a bias in fertilization success. However, its importance in nonrandom reproductive success is poorly resolved due to challenges distinguishing the roles of females and males in generating patterns of fertilization bias. Nevertheless, two CFC mechanisms have recently been documented and characterized in Drosophila simulans within the context of gametic isolation in competitive hybrid matings with Drosophila mau…

Demographic history has shaped the strongly differentiated corkwing wrasse populations in Northern Europe

2019

Understanding the biological processes involved in genetic differentiation and divergence between populations within species is a pivotal aim in evolutionary biology. One particular phenomenon that requires clarification is the maintenance of genetic barriers despite the high potential for gene flow in the marine environment. Such patterns have been attributed to limited dispersal or local adaptation, and to a lesser extent to the demographic history of the species. The corkwing wrasse (Symphodus melops) is an example of a marine fish species where regions of particular strong divergence are observed. One such genetic break occurred at a surprisingly small spatial scale (FST ~0.1), over a s…

Long-Distance Travellers: Phylogeography of a Generalist Parasite, Pholeter gastrophilus, from Cetaceans

2017

We studied the phylogeography and historical demography of the most generalist digenean from cetaceans, Pholeter gastrophilus, exploring the effects of isolation by distance, ecological barriers and hosts' dispersal ability on the population structure of this parasite. The ITS2 rDNA, and the mitochondrial COI and ND1 from 68 individual parasites were analysed. Worms were collected from seven oceanic and coastal cetacean species from the south western Atlantic (SWA), central eastern Atlantic, north eastern Atlantic (NEA), and Mediterranean Sea. Pholeter gastrophilus was considered a single lineage because reciprocal monophyly was not detected in the ML cladogram of all individuals, and seque…

Social isolation causes downregulation of immune and stress response genes and behavioural changes in a social insect

2021

Humans and other social mammals experience isolation from their group as stressful, triggering behavioural and physiological anomalies that reduce fitness. While social isolation has been intensely studied in social mammals, it is less clear how social insects, which evolved sociality independently, respond to isolation. Here we examined whether the typical mammalian responses to social isolation, e.g., an impaired ability to interact socially and immune suppression are also found in social insects. We studied the consequences of social isolation on behaviour and brain gene expression in the ant Temnothorax nylanderi. Following isolation, workers interacted moderately less with adult nestma…

Age, sex, mating status, but not social isolation interact to shape basal immunity in a group-living insect

2017

International audience; Immunity is a crucial but costly trait. Individuals should therefore adjust their investment into immunity to their condition and infection risks, which are often determined by their age, sex, mating status and social environment. However, whether and how these four key factors can interact to shape basal immunity remains poorly understood. Here, we tested the simultaneous effects of these factors on hemocyte concentration and phenoloxidase activity in adults of the European earwig. We found that hemocyte concentration increased with age, and that this increase was stronger in males. We also found an age-dependent increase in phenoloxidase activity in males and virgi…