Parasitic Effects Research Articles

103 Impact of Fescue Variety on Fecal Egg Counts in Mature Beef Cattle

Abstract Fescue toxicosis decreases beef cattle performance in a multitude of ways, including decreased health and immunity. Cattle challenged by fescue toxicosis are often grazing in an environment favorable for development of gastrointestinal nematodes (GIN). Interactions of fescue toxicosis and parasite challenge may result in further performance and economic losses. Many beef producers treat animals regularly for GIN parasites with little insight on necessity or effectiveness of anthelmintic products. Overuse of anthelmintics can result in development of anthelmintic resistance in GIN populations. To minimize the development of anthelmintic resistance, implementation of selective deworming practices should be considered. However, level of parasite burden and effects of fescue toxicosis on parasite burden need to be better understood in beef cattle herds before recommendations can be offered. Therefore, the objective was to investigate the impact of fescue toxicosis on GIN parasite infection rates through fecal egg counts (FEC), body weight (BW), hematocrit (HCT), and body condition score (BCS). Starting in April, for 14 consecutive weeks post-weaning, pregnant Angus-based cows (2 to 4 years old, n = 65) were rotationally grazed on either novel endophyte (EN) fescue or endophyte-infected (EI) fescue pastures. Hematocrit, BCS, and BW were assessed weekly, while FEC were measured bi-weekly to monitor the physiological changes as a result of consuming endophyte-infected tall fescue. All data were analyzed using Proc MIXED in SAS with repeated measures. Statistical significance was declared at P ≤ 0.05 and a trend at 0.10 > P > 0.05. Overall, FEC were low (4.2 ± 0.9 eggs/gm) in these mature cattle and grazing EI or EN fescue did not have any overall effect (P > 0.05) on the FEC. However, FEC decreased (P < 0.05) over the course of the study from week 1 to week 13. Body weight, HCT, and BCS were not affected (P > 0.05) by the type of fescue grazed. There was a tendency (P < 0.10) for 2-3 and 4-6 year old cattle to have lower BW when grazing EI compared with EN fescue while cattle >7 were not affected. Cattle gained BW (P < 0.05) over the 14-week study (471.4 and 527.7 ± 0.6 kg, 0 and4 week respectively). For cattle grazing EI fescue, HCT linearly decreased (P < 0.05) from week 1 to week 14 whereas cattle grazing EN fescue had a linear increase (P < 0.05) in HCT from week 1 to week 14. More research is warranted to investigate beef cattle FEC and the potential impact of fescue type on FEC in younger beef cattle.

Prevalence of Trypanosoma lainsoni and its effects of parasitism on the health of non-volant small mammals from the Brazilian Cerrado.

Small mammals are important hosts and/or reservoirs of Trypanosoma spp. This study aimed to verify the prevalence of Trypanosoma spp. in non-volant small mammals from the Brazilian Cerrado and to test the effects of T. lainsoni on the neutrophil/lymphocyte ratio (N/L) and body condition in rodent and marsupial populations. For this, we collected blood samples of 293 individuals captured in five forest fragments between 2019 and 2020. Blood was used to prepare the blood smears and packed on filter paper for DNA extraction. Generalized linear models were performed to test the effects of T. lainsoni on host health. The DNA was submitted to nested PCR targeting the Trypanosoma spp. 18S rRNA gene. From blood smears analyzed by microscopy, we obtained a positivity rate of 7.2% for Trypanosoma spp. About 31.1% of Gracilinanus agilis, Didelphis albiventris, and Rhipidomys macrurus samples were positive in nested PCR. From the obtained sequences, 83.3% were genetically identical to T. lainsoni and about 11% to T. cruzi TcI. In addition, we reported the infection of T. lainsoni in Hylaeamys megacephalus. We suggest that T. lainsoni does not influence the body condition and N/L ratio for either G. agilis or R. macrurus. Overall, our results expand the host list of T. lainsoni and demonstrate the infection of small mammals by T. cruzi TcI in peri-urban areas.

Wearable Rectenna With Integrated Miniaturized Feeding Slot and Rectifier Structure

A low-cost hybrid textile/PCB wearable rectenna is designed for smart on-body applications. It is an integration of a textile patch antenna and a highly efficient rectifier on a small PCB substrate, where the feeding aperture of the antenna is significantly miniaturized by exploiting an LC loading technique in order to have an effective integration with the rectifier. The feeding-rectifying circuitry is attached to the back of the antenna by normal sewing threads. The essential components are soldered on the small rigid PCB for a robust connection. The size of the rectenna is 0.817 × 0.817 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while the rigid substrate area for the feeding-rectifying circuitry is only 0.278 × 0.147 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (3.4 cm × 1.8 cm) at 2.45 GHz. The intrinsic dielectric/conduction loss of textile feedlines, the loss of antenna-to-rectifier interconnectors, the loss of soldering or gluing on textiles, and the loss due to body absorption from typical large feeding slots are constitutively reduced. The soldering points and the consequent hard-to-be-characterized parasitic effects on textiles are avoided. The proposed integration approach reduces the cost and eases the rectenna design, fabrication, and integration. As a result, the power conversion efficiency (PCE) of the rectifier reaches up to 39.5% at -20 dBm input power level whilst the experimental rectenna prototype achieves the state-of-the-art PCE of 41% at an extremely low incident power density of 0.4 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The maximum PCE is 56% at the -5 dBm input power. Finally, the possibility of harvesting datalink energy from PC/mobile phones as power source for wearable electronics is investigated.

Effect of malaria parasites’ infection on CD4 cells, haemopoietic cells and haemopoietic factors

Abstract Malariology Immunity is essential for understanding the pathology, treatment &amp; vaccine production. Changes in CD4, haemopoietic cells &amp; factors (RBC/HB/PCV/MCV/MCH &amp; MCHC) in malaria parasites-infected patients were studied at a teaching hospital in Enugu, Nigeria. 45 patients on doctor’s provisional diagnosis of malaria were examined for Plasmodiuminfections &amp; the degree of parasitaemia (0/+/++/&amp; +++). Positive (+) &amp; negative (0) samples were thereafter counted for CD4/haemopoietic cells &amp; factors using Flow Cytometry/Automated Blood Cell Counter, respectively. Plasmodium-negative specimens were within reference ranges for CD4 cell count (464–1308); mean value: 835. Fifteen (+) parasitaemia showed lower ranges of CD4 count (502–1282); mean: 678; with immune falls in one (427). Nine from twelve (++) parasitaemia showed crash in CD4 cells counts, range: 301–415; mean: 399. Seven (+++) parasitaemia showed crashes in CD4 cell counts, range: 160–357; mean: 225. Significant rise with increase in parasitaemia occurs in neutrophils and Total WBC. Opposite occurred in the three other primary immune cells &amp; platelets. There were variances in the basic immune cells’ percent &amp; numeric. The haemoglobin factors didn’t exhibited significant change, except platelet that showed marked steady decrease with increase in parasitaemia. Plasmodiuminfection causes immunosuppression in patients, vivid changes in haemopoietic cells populations/percentages, &amp; platelets. Malaria infection in the immunodeficients patients shouldaccelerate the complications, including death, unlike prevailing reports. Haemolytic anaemia in malaria is likely complication resulting only from chronic cases since there was no vivid anaemia in this study None

Experimental investigation of parasitic side effects in MOSFET-based multilevel inverter for electric vehicle applications

Experimental investigation of parasitic side effects in MOSFET-based multilevel inverter for electric vehicle applications

Sharing Best Practices [President’s message

As I read the titles of the articles in this month’s <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Industry Applications Magazine</i> , I am struck with the realization that the topics cover one of the areas of engineering where I think IEEE excels, and those of us who work in engineering education need to do more. Engineering schools at both the undergraduate and graduate levels are generally set up to teach similar topics. We cover fundamentals, the application of those ideas, analysis of systems under defined operating conditions, and design of new systems. In higher level electrical power engineering programs, we teach principles of protection, and, in some research groups, there is excellent work on fault detection. However, the articles in this issue of the magazine are clearly focused on the applied practice of engineering: best practices learned beyond technical requirements, determining when equipment is aged to the point when replacement is necessary, the causes and effects of undesired parasitic effects, and outage prevention as opposed to remedial action after a fault.

A Front-End CMOS Interface Circuit With High Voltage Charge Pump and Oscillator for Capacitive Micromachined Ultrasonic Transducers

Label-free biosensors, combined with miniaturized micro-electromechanical sensory platforms, offer an attractive solution for real-time and facile monitoring of biomolecules due to their high sensitivity and selectivity without the need for specifically labeling. Resonators have been acknowledged as an efficient technology for measuring biomolecular binding events including those involving nucleic acid and antibody. Among these, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as a promising candidate for biosensing. However, their usage is often limited by the requirement for high voltage supply and continuous frequency tracking, which can result in significant parasitic effects and measurement errors. In this paper, we present a novel front-end interface circuit for a CMUTs-based biosensor. The circuit, fabricated using TSMC 0.18-μX;Jm Bipolar-CMOS-DMOS (BCD) technology, incorporates an on-chip high voltage charge pump and feedback frequency monitoring. The CMUTs array features 20×20 circular cells, fabricated using a low-temperature direct bonding technology, with an experimental parallel-resonant frequency of 1.724 MHz and a high quality factor of up to 40.9. To fit the measured electrical characteristics, a five-element equivalent lumped element model is proposed. The high voltage charge pump provides an output voltage of 20 V, while the feedback oscillator has a ms-level start-up time and a total power dissipation of 3.8 mW. The proposed front-end interface is designed to function as a stand-alone chip for CMUTs-based resonant biodetection.

A Generalized Scalar Potential Integral Equation Formulation for the DC Analysis of Conductors

The electrostatic modeling of conductors is a fundamental challenge in various applications, including the prediction of parasitic effects in electrical interconnects, the design of biasing networks, and the modeling of biological, microelectromechanical, and sensing systems. The boundary element method (BEM) can be an effective simulation tool for these problems because it allows modeling three-dimensional objects with only a surface mesh. However, existing BEM formulations can be restrictive because they make assumptions specific to particular applications. For example, capacitance extraction formulations usually assume a constant electric scalar potential on the surface of each conductor and cannot be used to model a flowing current, nor to extract the resistance. When modeling steady currents, many existing techniques do not address mathematical challenges such as the null space associated with the operators representing the internal region of a conductor. We propose a more general BEM framework based on the electric scalar potential for modeling conductive objects in various scenarios in a unified manner. Restrictive application-specific assumptions are not made, and the aforementioned operator null space is handled in an intuitive and rigorous manner. Numerical examples drawn from diverse applications confirm the accuracy and generality of the proposed method.

Parasitic Fauna of Captive Snakes (Serpentes, Colubridae) from Northeastern Argentina

This study aimed to evaluate the status of parasitic infections of colubrid snakes living in serpentariums in northeastern Argentina. Specimens were analyzed through clinical examination and coproparasitological surveys. In cases of death, specimens were necropsied, and histopathological exams were performed to determine its cause(s). Out of 30 specimens examined from 12 different species, parasites were found in 25 of them (83%). Nematodes were most common, with rhabdiasid and ascaridid helminths accounting for 57% and 40% of all infections, respectively. Further, the ascarid Hexametra boddaertii was identified in a specimen of Erythrolamprus aesculapii. Coccidian, digenean, and pentastomid parasites were also found less frequently. We identified the pentastomids Raillietiella furcocerca and Cephalobaena tetrapoda in specimens of Pseudablabes patagoniensis. We revealed systemic lesions induced by endoparasites, including enteritis and detachment of the gut mucosa by ascarids, tissue granulomas by rhabdiasids, and pulmonary microhemorrhages by pentastomids. Additionally, rhabdiasid-induced lesions in Duvernoy's gland were shown for the first time. Regarding ectoparasites, we identified the tick Amblyomma dissimile in a specimen of P. patagoniensis. On the whole, this study provides relevant information about the prevalence and pathophysiological effects of parasites on captive colubrids and paves the way for treatment strategies of such infections.

Modeling and Analytical Description of Parasitic Probe Effects in Measurements of Conductor-Backed Coplanar Waveguides

Abstract. On-wafer measurements are of fundamental importance to the characterization of active and passive devices at millimetre-wave frequencies. They have been commonly known to be ambitious and challenging due to the occurrence of parasitic effects originating from probes, multimode propagation, crosstalk between adjacent structures and radiation. While a lot of investigations have been performed for conventional coplanar waveguides (CPW) measured on ceramic chucks, the parasitic effects occuring in conductor-backed CPWs (CB-CPWs) have not been fully understood yet. Therefore, this paper presents a thorough study for CB-CPWs based on electromagnetic simulations. Additionally, this paper proposes an analytical description accounting for the probe geometries to predict the occurrence of resonance effects due to the propagation of the parallel-plate-line (PPL) mode. For the first time, a new analytical description including the effects of the probe geometries is presented and validated by both measurements and simulations.

Are whole‐organism performance and thermal preference linked to endo‐ and ectoparasites in a short‐lived lizard?

AbstractWild animals are often concurrently infected by multiple parasites, which are assumed to negatively affect their host by exploiting the host's resources. The cumulative effect of parasite infections is often not studied. Despite this assumption, many hosts do not suffer significant costs from parasitism in the wild. Hosts can adapt to parasitic infections by mounting physiological and behavioural defences. A commonly used behavioural defence by ectotherms is to frequently visit warm environments to increase body temperature (i.e., behavioural fever) and thereby mount an immune response to parasites. Using the Australian common garden skink (Lampropholis guichenoti), we investigated the cumulative effect of endo‐ and ectoparasites on host performance. First, we investigated whether endo‐ and ectoparasites were associated with whole‐organism performance in the lizards. Second, we explored whether host individuals responded to their parasite infection through thermoregulatory behaviour. We found no significant relationship between parasitism and body condition. However, the infection with ectoparasitic mites was significantly related to reduced sprint speed, while the nematode infection had no significant relationship with any of our three performance measures (sprint speed, endurance and foraging efficiency). We showed no evidence of behavioural fever and infected lizards did not differ in their body temperature from uninfected lizards. Our findings suggest that short‐lived lizards may simply endure parasitic infections. The study provides an important example of how multiple infections with endo‐ and ectoparasites affect their host. It adds to the growing evidence for a negligible effect of parasites on host whole‐organism performance.

Stable pulsed operation of Lissajous structured beams by Nd:YVO4/Cr4+:YAG laser in a concave-convex resonator.

A Nd:YVO4/Cr4+:YAG laser with a symmetric concave-convex cavity ensuring strong intracavity beam focusing on the absorber is designed for stable pulsed operation of Lissajous structured modes with transverse patterns as Lissajous figures. Setting the cavity length to fulfill the criterion for efficient passive Q switching (PQS), as well as to meet the accidental degenerate conditions, Lissajous pulsed beams with well-defined structures and good temporal stability are created under two-dimensional off-axis pumping. Although the multi-transverse-mode oscillation inevitably induces asynchronous pulsation and leads the short-term pulse profiles to reveal parasitic effects, the overall long-term behavior of Lissajous pulses can be kept regular with amplitude fluctuations ≤15% and pulse-to-pulse timing jitter ≤5%. With the maximum peak power exceeding 500 W at a pump power of 4.5 W, the PQS Lissajous modes are further transformed into trochoidal pulsed beams to realize high-order and high-peak power structured vortex fields.

Modeling the effects of plant resistance, herbivore virulence, and parasitism, on the population dynamics of aphids and parasitoids in wheat and soybean in different climates

Invasions by insects that become pests are an increasing problem for agriculture. Introductions of parasitoids from the regions of pest origin and breeding plants resistant to invasive pests can reduce the abundances and impacts of pests, while providing safe, sustainable alternatives to insecticides. However, impacts of parasitoids and plant resistance are likely to interact, and the abiotic environment, and in particular, climate change is likely to affect these interactions. Here I report results from simulations with mathematical models of population dynamics of aphids and parasitoids on resistant versus susceptible plants, parameterized with published results, designed to test the following hypotheses: (1) parasitoids can reduce abundances and frequencies of virulent aphids able to overcome plant resistance, (2) temperature regime affects the impacts of parasitoids on virulent aphids, and (3) the outcomes of these interactions vary with crop. Two systems were modeled: the soybean aphid, Aphis glycines, on soybean, and the Russian wheat aphid, Diuraphis noxia, on wheat. The parasitoids in the models are in the genus Aphelinus, species of which have a long association with biological control of invasive pests. In the simulations with these models, parasitoids reduced the abundances, and on wheat, the percent of virulent aphids. The impacts of parasitoids on virulent aphids were greater in southern locations than in northern locations, and the impacts on virulent aphids were greater on wheat than on soybean. Indeed, parasitoids actually increased the frequencies of virulent aphids on soybean when only susceptible plants were present, while reducing the abundance of all aphids. If one accepts that comparisons of population dynamics in southern versus northern locations indicate the likely affects of climate change in the northern locations, these results suggest that climate change would lead to decreased abundance and frequency of virulent aphids in northern locations.

Computer Interface for Electroluminescence (EL)

The goal of Computer aided device start from the physical description of integrated circuit devices, considering both the physical configuration and related device properties and build the link between the broad range of physics and electrical behavior models that support circuit design. Physics-based modeling of devices, is distributed and lumped form is an essential part of the IC process development. It seeks to quantify the underlying understanding of the technology and abstract that knowledge to the device design level, including extraction of the key parameters that support circuit design and statistical metrology [1][2]. IC development for more than a quarter-century has been dominated by the MOS technology. In the 1970s and 1980s NMOS was favored owing to speed and area advantages, coupled with technology limitations and concerns related to isolation, parasitic effects and process complexity. During that era of NMOS-dominated LSI and the emergence of VLSI, the fundamental scaling laws of MOS technology were codified and broadly applied [3]. It was also during this period that Computer Aided Device reached maturity in terms of realizing robust process modeling (primarily one-dimensional) which then became an integral technology design tool, used universally across the industry [4]. At the same time device simulation, dominantly two-dimensional owing to the nature of MOS devices, became the work-horse of technologists in the design and scaling of devices [5]. The transition from NMOS to CMOS technology resulted in the necessity of tightly coupled and fully 2D simulators for process and device simulations [6][7].

Quantum back-action limits in dispersively measured Bose-Einstein condensates

A fundamental tenet of quantum mechanics is that measurements change a system’s wavefunction to that most consistent with the measurement outcome, even if no observer is present. Weak measurements produce only limited information about the system, and as a result only minimally change the system’s state. Here, we theoretically and experimentally characterize quantum back-action in atomic Bose-Einstein condensates interacting with a far-from resonant laser beam. We theoretically describe this process using a quantum trajectories approach where the environment measures the scattered light and present a measurement model based on an ideal photodetection mechanism. We experimentally quantify the resulting wavefunction change in terms of the contrast of a Ramsey interferometer and control parasitic effects associated with the measurement process. The observed back-action is in good agreement with our measurement model; this result is a necessary precursor for achieving true quantum back-action limited measurements of quantum gases.

The opposing roles of lethal and nonlethal effects of parasites on host resource consumption.

Although parasites can kill their hosts, they also commonly cause nonlethal effects on their hosts, such as altered behaviors or feeding rates. Both the lethal and nonlethal effects of parasites can influence host resource consumption. However, few studies have explicitly examined the joint lethal and nonlethal effects of parasites to understand the net impacts of parasitism on host resource consumption. To do this, we adapted equations used in the indirect effects literature to quantify how parasites jointly influence basal resource consumption through nonlethal effects (altered host feeding rate) and lethal effects (increased host mortality). To parametrize these equations and to examine the potential temperature sensitivity of parasite influences, we conducted a fully factorial lab experiment (crossing trematode infection status and a range of temperatures) to quantify feeding rates and survivorship curves of snail hosts. We found that infected snails had significantly higher mortality and ate nearly twice as much as uninfected snails and had significantly higher mortality, resulting in negative lethal effects and positive nonlethal effects of trematodes on host resource consumption. The net effects of parasites on resource consumption were overall positive in this system, but did vary with temperature and experimental duration, highlighting the context dependency of outcomes for the host and ecosystem. Our work demonstrates the importance of jointly investigating lethal and nonlethal effects of parasites and provides a novel framework for doing so.

Effects of a radial variation of surface coefficients on plasma uniformity in capacitive RF discharges

With the increasing demands toward large area plasma etching and deposition, the radial uniformity of capacitively coupled plasmas (CCPs) becomes one of the key factors that determine process performance in industrial applications. However, there is a variety of parasitic effects, e.g. electromagnetic and electrostatic edge effects, that typically lead to the formation of nonuniform radial plasma density profiles at various discharge conditions with a density peak appearing either at the center or near the edges of the electrodes. Moreover, in commercial CCPs different surface materials are in contact with the plasma at various positions as parts of boundary surfaces such as focus rings, masks, showerhead electrodes, wall and/or target materials. Via complex material specific plasma-surface interactions, the presence of such different surface materials affects plasma uniformity in a way that is typically not understood and, thus, not controlled. In this work, aided by 2d3v graphics processing unit accelerated particle-in-cell/Monte Carlo collision simulations, we study the effects of radial variations of electrode materials on the plasma via their different ion and electron induced secondary electron emission as well as electron reflection coefficients on the discharge characteristics. Based on such fundamental understanding we tailor the radial variation of boundary surface materials to improve plasma uniformity in low pressure CCPs. Such investigations are performed at different neutral gas pressures, where both center and edge high radial plasma density profiles form in the presence of radially uniform surface coefficients that resemble the presence of a single electrode material. It is demonstrated that by radially varying the surface coefficients at the grounded electrode, the radial plasma density profile can be finely adjusted and the plasma uniformity above the wafer placed at the powered electrode can be improved in both cases.

Investigation of an expanded, lumped-element model of electropenetrography (EPG) and the accuracy of the traditional R and emf model

Electropenetrography (EPG) allows researchers to measure feeding behaviors of piercing-sucking pests such as aphids and mosquitoes. The presently accepted electrical circuit model of an EPG monitor shows excitation voltage (Vin) applied to a feeding substrate (such as a plant), then interacting with a variable resistor (Ra) representing the feeding insect, plus biopotentials generated in the plant-insect interface (Vemf). Together, Ra and Vemf then interact with the input resistor (Ri) of the first amplifier in the monitor. After signal processing, variable voltage output (Vout) results in waveforms that represent insect feeding. The present work performed a lumped-element circuit analysis to determine whether the above simple model was correct by today’s electrical engineering standards. This work showed that the above model was too simple to explain EPG signals. The newly developed model adds valuable information on parasitic effects such as capacitance in the amplifier (Ci) and from poor insect tethering (Cai), as well as effects of filtering due to induction (Lp) and capacitance (Cp) in the plant. This work recommends specific steps to avoid these problems. In addition, it was found that the insect is a complex electrical system, now symbolized by Za for impedance. Yet, despite the findings of both parasitic and complex, new elements in the EPG model, this work fundamentally supports the foundation of EPG science. That is, it confirms that the emf and still-named R components exist and can provide the basis for interpretation of EPG waveforms. Nonetheless, designers and researchers must be alert to potential problems with parasitic elements in the EPG circuit and take active steps to reduce them. These findings provide important benchmark data for future studies of the nature of Za, especially its importance in interpreting waveforms in the context of the crucial emf and R responsiveness curves. Together with the present study, such analysis will enable improvements in future EPG monitor designs.

Parasitization of Aphis gossypii Glover by Binodoxys communis Gahan Causes Shifts in the Ovarian Bacterial Microbiota.

Aphis gossypii Glover is an important agricultural pest distributed worldwide. Binodoxys communis Gahan is the main parasitoid wasp of A. gossypii. Previous studies have shown that parasitization causes reduced egg production in A. gossypii, but the effects of parasitism on the symbiotic bacteria in the host ovaries are unknown. In this study, we analyzed the microbial communities in the ovaries of A. gossypii without and after parasitization. Whether parasitized or not, Buchnera was the dominant genus of symbiotic bacteria in the ovaries, followed by facultative symbionts including Arsenophonus, Pseudomonas, and Acinetobacter. The relative abundance of Buchnera in the aphid ovary increased after parasitization for 1 d in both third-instar nymph and adult stages, but decreased after parasitization for 3 d. The shifts in the relative abundance of Arsenophonus in both stages were the same as those observed for Buchnera. In addition, the relative abundance of Serratia remarkably decreased after parasitization for 1 d and increased after parasitization for 3 d. A functional predictive analysis of the control and parasitized ovary microbiomes revealed that pathways primarily enriched in parasitization were "amino acid transport and metabolism" and "energy production and conversion." Finally, RT-qPCR analysis was performed on Buchnera, Arsenophonus, and Serratia. The results of RT-qPCR were the same as the results of 16S rDNA sequencing. These results provide a framework for investigating shifts in the microbial communities in host ovaries, which may be responsible for reduced egg production in aphids. These findings also broaden our understanding of the interactions among aphids, parasitoid wasps, and endosymbionts.

GaN and SiC Device Characterization by a Dedicated Embedded Measurement System

This work proposes a comparison among GaN and SiC device main parameters measured with a dedicated and low-cost embedded system, employing an STM32 microcontroller designed to the purpose. The system has the advantage to avoid the use of expensive laboratory measurement equipment to test the devices, allowing to obtain their behavior in operating conditions. The following KPIs (Key Performance Indicators) are measured and critically compared: threshold voltage, on-resistance and input capacitance. All the measurements are carried out in a short time interval and on a wide range of switching frequencies, ranging from 10 kHz to 1 MHz. This investigation is focused on the deviation of the figures of merit when the switching frequency changes, since it is crucial for wide-bandgap devices. The devised, low-cost, microcontroller unit allows high flexibility and system portability, while the employed equivalent-time sampling technique overcomes some issues related to the need of high sampling frequency. It allows good performances with common microcontroller embedded AD converters. To validate the proposed system, the obtained results have been compared with the time-domain waveforms acquired with a traditional laboratory oscilloscope and a study of the system’s measurement errors has been carried out. Results show that GaN devices achieve a higher efficiency with respect to SiC devices in the considered range of switching frequencies. The on-resistance exhibited by GaN devices shows, as expected, an increase with frequency, which happens to switching losses, too. On the other hand, GaN devices are more sensitive to parasitic effects and the high dV/dt, due to the reduced switching times, can excite unwanted ringing phenomena.