359 research outputs found
Effects of Thiamethoxam on Vespula Germanica (F.) (Hymenoptera: Vespidae)
Damage of pesticides used in agriculture on non-target organisms (except honey bees) is not sufficiently considered and neglected. Studies showed that wild bees, like honey bees, were also affected by pesticides. Wild bee species should also be protected because of their importance in pollination and biological control and also in order to protect biodiversity. Effects of pesticides on wild bees should be investigated without delay and precautions should be taken to protect the generations of wildlife. In addition, while increasing the agricultural areas, habitat for wild pollinators should be established.In this study, effect of Thiamethoxam, an agriculturally active agent in the neonicotinoid group, commonly used in agriculture fields, on the European wasp (Vespula germanica) was investigated. For this purpose, 2 molar carnation-flavored syrup in a petri dish was placed in a field where wild bees are frequent, and wild bees had got accustomed there. Trial doses were prepared with thiamethoxam dose commonly used in agricultural areas (15 ml/100 L water) and 50% dilutions of this dose (15.00, 7.50, 3.75, 1.87, 0.93, 0.46, 0.23, 0.12, 0.06 ml/100 L water) and fed in 2 molar syrup. Those who returned to the carnation petri dish after feeding were recorded at the 1st, 4th and 24th hours.At the end of the study, bees fed with 15.00, 7.50, and 3.75 ml / 100 L doses of the pesticide all died. One hour after pesticide ingestion, 84.73% of the control group and 13.33% of the bees fed with 1.87 ml / 100L dose, were alive and returned to the syrup petri dish
Techno-economic analysis of on-site energy storage units to mitigate wind energy curtailment : a case study in Scotland
Wind energy plays a major role in decarbonisation of the electricity sector and supports achieving net-zero greenhouse gas emissions. Over the last decade, the wind energy deployments have grown steadily, accounting for more than one fourth of the annual electricity generation in countries like the United Kingdom, Denmark, and Germany. However, as the share of wind energy increases, system operators face challenges in managing excessive wind generation due to its nondispatchable nature. Currently, the most common practice is wind energy curtailment in which wind farm operators receive constraint payments to reduce their renewable energy production. This practice not only leads to wastage of large volumes of renewable energy, but also the associated financial cost is reflected to rate payers in the form of increased electricity bills. On-site energy storage technologies come to the forefront as a technology option to minimise wind energy curtailment and to harness wind energy in a more efficient way. To that end, this paper, first, systematically evaluates different energy storage options for wind energy farms. Second, a depth analysis of curtailment and constraint payments of major wind energy farms in Scotland are presented. Third, using actual wind and market datasets, a techno-economic analysis is conducted to examine the relationship between on-site energy storage size and the amount of curtailment. The results show that, similar to recent deployments, lithium-ion technology is best suited for on-site storage. As case studies, Whitelee and Gordon bush wind farms in Scotland are chosen. The most suitable storage capacities for 20 years payback period is calculated as follows: (i) the storage size for the Gordonbush wind farm is 100 MWh and almost 19% of total curtailment can be avoided and (ii) the storage size for the Whitlee farm is 125 MWh which can reduce the curtailment by 20.2%. The outcomes of this study will shed light into analysing curtailment reduction potential of future wind farms including floating islands, seaports, and other floating systems
Intraoperative cerebral hemodynamic monitoring during carotid endarterectomy via diffuse correlation spectroscopy and near-infrared spectroscopy
Objective: This pilot study aims to show the feasibility of noninvasive and real-time cerebral hemodynamic monitoring during carotid endarterectomy (CEA) via diffuse correlation spectroscopy (DCS) and near-infrared spectroscopy (NIRS). Methods: Cerebral blood flow index (CBFi) was measured unilaterally in seven patients and bilaterally in seventeen patients via DCS. In fourteen patients, hemoglobin oxygenation changes were measured bilaterally and simultaneously via NIRS. Cerebral autoregulation (CAR) and cerebrovascular resistance (CVR) were estimated using CBFi and arterial blood pressure data. Further, compensatory responses to the ipsilateral hemisphere were investigated at different contralateral stenosis levels. Results: Clamping of carotid arteries caused a sharp increase of CVR (~70%) and a marked decrease of ipsilateral CBFi (57%). From the initial drop, we observed partial recovery in CBFi, an increase of blood volume, and a reduction in CVR in the ipsilateral hemisphere. There were no significant changes in compensatory responses between different contralateral stenosis levels as CAR was intact in both hemispheres throughout the CEA phase. A comparison between hemispheric CBFi showed lower ipsilateral levels during the CEA and post-CEA phases (p < 0.001, 0.03). Conclusion: DCS alone or combined with NIRS is a useful monitoring technique for real-time assessment of cerebral hemodynamic changes and allows individualized strategies to improve cerebral perfusion during CEA by identifying different hemodynamic metrics.</p
Four-channel System for Characterization of Josephson Parametric Amplifiers
The axion search experiments based on haloscopes at the Center for Axion and
Precision Physics Research (CAPP) of the Institute for Basic Science (IBS) in
South Korea are performed in the frequency range from 1 GHz to 6 GHz. In order
to perform the experiments in a strong magnetic field of 12 T and a
large-volume cavity of close to 40 liters, we use He wet dilution refrigerators
with immersed superconducting magnets. The measurements require continuous
operation for months without interruptions for microwave component
replacements. This is achieved by using different cryogenic engineering
approaches including microwave RF-switching. The critical components, defining
the scanning rate and the sensitivity of the setup, are the Josephson
parametric amplifiers (JPA) and cryogenic low noise amplifiers (cLNA) based on
high-electron-mobility-transistor (HEMT) technology. It is desirable for both
devices to have a wide frequency range and low noise close to the quantum limit
for the JPA. In this paper, we show a recent design of a 4-channel measurement
setup for JPA and HEMT measurements. The setup is based on a 4-channel wideband
noise source (NS) and is used for both JPA and HEMT gain and noise
measurements. The setup is placed at 20 mK inside the dry dilution
refrigerator. The NS is thermally decoupled from the environment using plastic
spacers, superconducting wires and superconducting coaxial cables. We show the
gain and noise temperature curves measured for 4 HEMT amplifiers and 2 JPAs in
one cool-downComment: to be published in JPS Conference Proceedings (LT29
CAPP Axion Search Experiments with Quantum Noise Limited Amplifiers
The axion is expected to solve the strong CP problem of quantum
chromodynamics and is one of the leading candidates for dark matter. CAPP in
South Korea has several axion search experiments based on cavity haloscopes in
the frequency range of 1-6 GHz. The main effort focuses on operation of the
experiments with the highest possible sensitivity. It requires maintenance of
the haloscopes at the lowest physical temperature in the range of mK and usage
of low noise components to amplify the weak axion signal. We report development
and operation of low noise amplifiers for 5 haloscope experiments targeting at
different frequency ranges. The amplifiers show noise temperatures approaching
the quantum limit.Comment: 6 pages, 7 figures, 29th International Conference on Low Temperature
Physics, August 18-24, 2022, Sapporo, Japa
Josephson Parametric Amplifier in Axion Experiments
The axion is a hypothetical particle, a promising candidate for dark matter,
and a solution to the strong CP problem. Axion haloscope search experiments
deal with a signal power comparable to noise uncertainty at millikelvin
temperature. We use a flux-driven Josephson parametric amplifier (JPA) with the
aim of approaching a noise level near the theoretically allowed limit of half
quanta. In our measurements to characterize the JPA we have found the added
noise to the system with a JPA as the first-stage amplifier to be lower than
110 mK at the frequencies from 0.938 GHz to 0.963 GHz.Comment: to be published in JPS Conference Proceedings (LT29
Photonic quantum state transfer between a cold atomic gas and a crystal
Interfacing fundamentally different quantum systems is key to build future
hybrid quantum networks. Such heterogeneous networks offer superior
capabilities compared to their homogeneous counterparts as they merge
individual advantages of disparate quantum nodes in a single network
architecture. However, only very few investigations on optical
hybrid-interconnections have been carried out due to the high fundamental and
technological challenges, which involve e.g. wavelength and bandwidth matching
of the interfacing photons. Here we report the first optical quantum
interconnection between two disparate matter quantum systems with photon
storage capabilities. We show that a quantum state can be faithfully
transferred between a cold atomic ensemble and a rare-earth doped crystal via a
single photon at telecommunication wavelength, using cascaded quantum frequency
conversion. We first demonstrate that quantum correlations between a photon and
a single collective spin excitation in the cold atomic ensemble can be
transferred onto the solid-state system. We also show that single-photon
time-bin qubits generated in the cold atomic ensemble can be converted, stored
and retrieved from the crystal with a conditional qubit fidelity of more than
. Our results open prospects to optically connect quantum nodes with
different capabilities and represent an important step towards the realization
of large-scale hybrid quantum networks
PTPN2, a Candidate Gene for Type 1 Diabetes, Modulates Interferon-γ–Induced Pancreatic β-Cell Apoptosis
OBJECTIVE:
The pathogenesis of type 1 diabetes has a strong genetic component. Genome-wide association scans recently identified novel susceptibility genes including the phosphatases PTPN22 and PTPN2. We hypothesized that PTPN2 plays a direct role in beta-cell demise and assessed PTPN2 expression in human islets and rat primary and clonal beta-cells, besides evaluating its role in cytokine-induced signaling and beta-cell apoptosis.
RESEARCH DESIGN AND METHODS:
PTPN2 mRNA and protein expression was evaluated by real-time PCR and Western blot. Small interfering (si)RNAs were used to inhibit the expression of PTPN2 and downstream STAT1 in beta-cells, allowing the assessment of cell death after cytokine treatment.
RESULTS:
PTPN2 mRNA and protein are expressed in human islets and rat beta-cells and upregulated by cytokines. Transfection with PTPN2 siRNAs inhibited basal- and cytokine-induced PTPN2 expression in rat beta-cells and dispersed human islets cells. Decreased PTPN2 expression exacerbated interleukin (IL)-1beta + interferon (IFN)-gamma-induced beta-cell apoptosis and turned IFN-gamma alone into a proapoptotic signal. Inhibition of PTPN2 amplified IFN-gamma-induced STAT1 phosphorylation, whereas double knockdown of both PTPN2 and STAT1 protected beta-cells against cytokine-induced apoptosis, suggesting that STAT1 hyperactivation is responsible for the aggravation of cytokine-induced beta-cell death in PTPN2-deficient cells.
CONCLUSIONS:
We identified a functional role for the type 1 diabetes candidate gene PTPN2 in modulating IFN-gamma signal transduction at the beta-cell level. PTPN2 regulates cytokine-induced apoptosis and may thereby contribute to the pathogenesis of type 1 diabetes
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