Comparative aspects of taste receptors and host plant selection in larvae of various Yponomeuta species (Lepidoptera)

Caterpillars perceive their food's taste by a limited number of receptor cells. As is shown in several studies reported in literature, gustation plays a crucial rôle in both qualitative and quantitative aspects of feeding responses. In this thesis, a comparative investigation on gustatory perception of plant constituents in several Yponomeuta species is described.The species studied, their associated hosts and stimuli applied are shown in Table 1 of the first chapter. Electrophysiological data were obtained by means of a tip recording technique. The sensory cells respond to stimulation by generating a train of action potentials (Fig. 1, chapter 1). A model which can explain the shape and magnitude of the recorded action potentials is described in chapter 6. Routinely the number of spikes during an arbitrary interval of stimulation served as response index. In addition some of the activities were analysed in greater detail. This type of analysis, taking into account the number of activities in each recording and their time courses is described in chapters 1 and 5. Several types of interspecific sensitivity spectra have been recorded and are represented in Table 2 and Fig. 6 in chapter 1. A classification of a complete array of responses was carried out by a cluster analysis and is described in the second chapter; it appears that most species can be distinguished on the basis of functional criteria (Fig. 1, chapter 2). As far as can be determined natural concentrations (Table 1, chapter 1) appear to be situated above receptor cell threshold levels (Fig. 6, chapter 1). General aspect on relationships between receptor cell sensitivity, natural concentrations and data processing by the central nervous system are described in chapter 7. Although the vertebrate olfactory system is used to illustrate the examples in the seventh chapter, the principles described are also valid for the insect gustatory system. In larvae of Y. cagnagellus and Y. evonymellus behavioural responses to some of the stimuli used in the electrophysiological experiments were determined (chapter 3). To study inheritance of gustatory sensitivity, F1 offspring of reciprocal crosses between Y.cagnagellus and Y. malinellus was tested for sensitivity to solutions of dulcitol, phloridzin, prunasin and sorbitol (chapter 4)

Natural Gas Compressibility Factor Measurement and Evaluation for High Pressure High Temperature Gas Reservoirs

The Natural gas compressibility factor is an important reservoir fluid property used in reservoir engineering computations either directly or indirectly in material balance calculations, well test analysis, gas reserve estimates, gas flow in lines and in numerical reservoir simulations. Existing gas compressibility factor correlations were derived using measured data at low to moderate pressures(less than 8, 000 psia) and temperatures (less than 212oF), and an extrapolation to High Pressure High temperature (HPHT) is doubtful. The need to understand and predict gas compressibility factor at HPHT has become increasingly important as exploration and production has moved to ever deeper formations where HPHT conditions are to be encountered. This paper presents laboratory measurement of gas compressibility factors at HPHT natural gas systems and the evaluation of some selected gas compressibility factors correlations. Samples of gas mixtures were collected from the high pressure gas reservoirs from the Niger Delta region of Nigeria. Vinci PVT Cell was used to measure the gas compressibility factors for a pressures ranging from 6,000 to 14,000 psia and temperatures at 270oF and 370oF. The new laboratory data was compared to some of the gas compressibility factor correlations/ models used in the petroleum industry. Results showed that majority of the correlations studied overestimated the gas compressibility factor at HPHT. Mean relative and absolute error analysis were done based on the temperature difference; it was found that the total mean relative and absolute errors for the 370o F cases are higher than those for 270oF. Among all the correlations assessed, Hall and Yarborough equation performed better than other existing correlations with a mean absolute error of 3.545 and relative error of -2.668 at 270oF. At 370oF, Beggs and Brills correlation predicted better than other correlations studied with a mean relative error of -4.77 and absolute error of 7.18

Study protocol for two randomised controlled trials evaluating the effects of Cerclage in the reduction of extreme preterm birth and perinatal mortality in twin pregnancies with a short cervix or dilatation:The TWIN Cerclage studies

Introduction:Twin pregnancies have a high risk of extreme preterm birth (PTB) at less than 28 weeks of gestation, which is associated with increased risk of neonatal morbidity and mortality. Currently there is a lack of effective treatments for women with a twin pregnancy and a short cervix or cervical dilatation. A possible effective surgical method to reduce extreme PTB in twin pregnancies with an asymptomatic short cervix or dilatation at midpregnancy is the placement of a vaginal cerclage. Methods and analysis: We designed two multicentre randomised trials involving eight hospitals in the Netherlands (sites in other countries may be added at a later date). Women older than 16 years with a twin pregnancy at &lt;24 weeks of gestation and an asymptomatic short cervix of ≤25 mm or cervical dilatation will be randomly allocated (1:1) to both trials on vaginal cerclage and standard treatment according to the current Dutch Society of Obstetrics and Gynaecology guideline (no cerclage). Permuted blocks sized 2 and 4 will be used to minimise the risk of disbalance. The primary outcome measure is PTB of &lt;28 weeks. Analyses will be by intention to treat. The first trial is to demonstrate a risk reduction from 25% to 10% in the short cervix group, for which 194 patients need to be recruited. The second trial is to demonstrate a risk reduction from 80% to 35% in the dilatation group and will recruit 44 women. A cost-effectiveness analysis will be performed from a societal perspective. Ethics and dissemination: This study has been approved by the Research Ethics Committees in the Netherlands on 3/30/2023. Participants will be required to sign an informed consent form. The results will be presented at conferences and published in a peer-reviewed journal. Participants will be informed about the results.</p

Study protocol for two randomised controlled trials evaluating the effects of Cerclage in the reduction of extreme preterm birth and perinatal mortality in twin pregnancies with a short cervix or dilatation:The TWIN Cerclage studies

Introduction:Twin pregnancies have a high risk of extreme preterm birth (PTB) at less than 28 weeks of gestation, which is associated with increased risk of neonatal morbidity and mortality. Currently there is a lack of effective treatments for women with a twin pregnancy and a short cervix or cervical dilatation. A possible effective surgical method to reduce extreme PTB in twin pregnancies with an asymptomatic short cervix or dilatation at midpregnancy is the placement of a vaginal cerclage. Methods and analysis: We designed two multicentre randomised trials involving eight hospitals in the Netherlands (sites in other countries may be added at a later date). Women older than 16 years with a twin pregnancy at &lt;24 weeks of gestation and an asymptomatic short cervix of ≤25 mm or cervical dilatation will be randomly allocated (1:1) to both trials on vaginal cerclage and standard treatment according to the current Dutch Society of Obstetrics and Gynaecology guideline (no cerclage). Permuted blocks sized 2 and 4 will be used to minimise the risk of disbalance. The primary outcome measure is PTB of &lt;28 weeks. Analyses will be by intention to treat. The first trial is to demonstrate a risk reduction from 25% to 10% in the short cervix group, for which 194 patients need to be recruited. The second trial is to demonstrate a risk reduction from 80% to 35% in the dilatation group and will recruit 44 women. A cost-effectiveness analysis will be performed from a societal perspective. Ethics and dissemination: This study has been approved by the Research Ethics Committees in the Netherlands on 3/30/2023. Participants will be required to sign an informed consent form. The results will be presented at conferences and published in a peer-reviewed journal. Participants will be informed about the results.</p

Emergent Oscillations in Networks of Stochastic Spiking Neurons

Networks of neurons produce diverse patterns of oscillations, arising from the network's global properties, the propensity of individual neurons to oscillate, or a mixture of the two. Here we describe noisy limit cycles and quasi-cycles, two related mechanisms underlying emergent oscillations in neuronal networks whose individual components, stochastic spiking neurons, do not themselves oscillate. Both mechanisms are shown to produce gamma band oscillations at the population level while individual neurons fire at a rate much lower than the population frequency. Spike trains in a network undergoing noisy limit cycles display a preferred period which is not found in the case of quasi-cycles, due to the even faster decay of phase information in quasi-cycles. These oscillations persist in sparsely connected networks, and variation of the network's connectivity results in variation of the oscillation frequency. A network of such neurons behaves as a stochastic perturbation of the deterministic Wilson-Cowan equations, and the network undergoes noisy limit cycles or quasi-cycles depending on whether these have limit cycles or a weakly stable focus. These mechanisms provide a new perspective on the emergence of rhythmic firing in neural networks, showing the coexistence of population-level oscillations with very irregular individual spike trains in a simple and general framework

Evaluation of low-dose aspirin in the prevention of recurrent spontaneous preterm labour (the APRIL study) : A multicentre, randomised, double-blinded, placebo-controlled trial

Funding: MdB, LV, TN, BM, MO and CdG received funding from ZonMw, The Dutch Organisation for Health Research and Development (grant number 836041006). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Olfactory receptors on the maxillary palps of small ermine moth larvae: evolutionary history of benzaldehyde sensitivity

In lepidopterous larvae the maxillary palps contain a large portion of the sensory equipment of the insect. Yet, knowledge about the sensitivity of these cells is limited. In this paper a morphological, behavioral, and electrophysiological investigation of the maxillary palps of Yponomeuta cagnagellus (Lepidoptera: Yponomeutidae) is presented. In addition to thermoreceptors, CO2 receptors, and gustatory receptors, evidence is reported for the existence of two groups of receptor cells sensitive to plant volatiles. Cells that are mainly sensitive to (E)-2-hexenal and hexanal or to (Z)-3-hexen-1-ol and 1-hexanol were found. Interestingly, a high sensitivity for benzaldehyde was also found. This compound is not known to be present in Euonymus europaeus, the host plant of the monophagous Yponomeuta cagnagellus, but it is a prominent compound in Rosaceae, the presumed hosts of the ancestors of Y. cagnagellus. To elucidate the evolutionary history of this sensitivity, and its possible role in host shifts, feeding responses of three Yponomeuta species to benzaldehyde were investigated. The results confirm the hypothesis that the sensitivity to benzaldehyde evolved during the ancestral shift from Celastraceae to Rosaceae and can be considered an evolutionary relict, retained in the recently backshifted Celastraceae-specialist Y. cagnagellus

Methods of electroencephalographic signal analysis for detection of small hidden changes

The aim of this study was to select and evaluate methods sensitive to reveal small hidden changes in the electroencephalographic (EEG) signal. Two original methods were considered