Terahertz near-field microscopy based on an air-plasma dynamic aperture

Schematic of THz near-field microscopy based on an air-plasma dynamic aperture. Two femtosecond laser pulses were focused in mutually perpendicular directions to generate two air-plasmas (Plasma1 and Plasma2) close to the sample surface. The incident THz beam was modulated by the cross-filament created by the air-plasmas and the reflected THz near-field signal was measured. The inset shows the relationships between the two air-plasmas, the THz beam, and the sample. Credit: Xin-ke Wang, Jia-sheng Ye, Wen-feng Sun, Peng Han, Lei Hou, and Yan Zhang

As a novel far-infrared inspection method, the development of terahertz (THz) imaging technology has attracted considerable attention in recent years. With the unique properties of THz radiation, such as non-ionizing photon energies and broad spectral information, this imaging technique has shown powerful application potential in many fundamental research and industrial fields. However, the resolution of THz imaging is always limited due to its long wavelength. The introduction of optical near-field techniques can greatly enhance the resolution, but it is always essential to require that a THz source or detector approach the sample from as far as possible. For soft or liquid materials in biomedical sensing and chemical inspection, these samples may be easily damaged and the THz source or detector may be contaminated in traditional THz near-field techniques. Hence, it still remains a challenge to achieve THz near-field microscopy in wider application fields.

In a new paper published in Light: Science & Applications, a team of scientists, led by Professors Xin-ke Wang and Yan Zhang from Beijing Key Laboratory of Metamaterials and Devices, Key Laboratory of Terahertz Optoelectronics Ministry of Education, Department of Physics, Capital Normal University, Beijing, China, and co-workers have developed a new THz near-field microscopy to achieve THz sub-wavelength imaging without approaching the sample with any devices.

In this THz near-field technique, a cross-filament was formed by two cross air-plasmas, which opened a dynamic aperture to modulate the intensity of a THz beam on a sample surface. When the cross-filament was close enough to the sample surface, THz imaging with the resolution of tens of microns was fulfilled. Taking advantages of this technique, the limitation of the sample choice was effectively removed in traditional THz near-field imaging and sample damage from the cross-filament was minimized.

To check the performance of the technique, four different kinds of materials were measured and their THz sub-wavelength images were successfully acquired, including a metallic resolution test chart, a semiconductor chip, a plastic pattern, and a greasy spot. In addition, the technique is also suitable in principle for an encapsulated sample, if its packaging is transparent to THz and visible light. Therefore, it could be anticipated that the reported method will significantly broaden applications of THz near-field microscopy, e.g., biomedical sensing and chemical inspection.

More information:
Xin-ke Wang et al, Terahertz near-field microscopy based on an air-plasma dynamic aperture, Light: Science & Applications (2022). DOI: 10.1038/s41377-022-00822-8

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Hexbyte Glen Cove Australian ‘rain bomb’ floods claim sixth life

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A girl looks at rising floodwaters of the Bremer river in West Ipswich, Queensland.

Flooding on Australia’s east coast claimed another life overnight, bringing the death toll from the extreme weather to six as a “rain bomb” continued to move south Sunday.

Police in the state of Queensland said a 34-year-old man had died after his car became submerged in floodwaters around 2:30am on Sunday (1530 GMT Saturday).

While the man was able to free himself from his vehicle and tried to swim to safety, he failed to surface and his body was found a short time later.

Huge downpours have battered eastern Australia for the better part of a week, unleashing decades-high floods, inundating homes and roads, and sweeping away cars.

Adrian Schrinner, lord mayor of Queensland’s capital city Brisbane, described the weather system as a “rain bomb above South East Queensland”.

State premier Annastacia Palaszczuk pleaded that people living in Brisbane stay home as the system moved south Sunday into major residential areas.

“This water is unrelenting at the moment,” she said.

With intense rain expected to continue into next week, more than 1,400 homes in Brisbane were at risk from the floodwaters, she said.

The Australian Bureau of Meteorology has issued flood warnings for vast swathes of Queensland and northern New South Wales, with more than 300 mm (11.8 inches) falling in some areas in the last 24 hours.

Police continue to search for a man in his 70s who fell into the Brisbane River on Friday.

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Hexbyte Glen Cove Honeybees show withdrawal symptoms when weaned off alcohol thumbnail

Hexbyte Glen Cove Honeybees show withdrawal symptoms when weaned off alcohol

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Credit: Pixabay/CC0 Public Domain

A team of researchers from Jagiellonian University and the Polish Academy of Sciences has found that honeybees fed a diet of alcohol-spiked food exhibit withdrawal symptoms when the alcohol is removed. In their paper published in the journal Biology Letters, the group describes experiments they conducted with honeybees and why they believe their findings are relevant to treatment of alcoholism in humans.

Prior research has found that studying the habits of other creatures can lead to new insights into —such research has sometimes involved the study of addiction in other animals. In this new effort, the researchers wondered about the impact of alcohol on —in the wild they are quite often exposed to naturally occurring alcohol in nectar.

To learn more about how alcohol might impact honeybees, the researchers set up several beehives in an area where their diet was restricted to the food given to them by the research team. The food for the bees consisted of a type of . Once the hives were set up, the researchers added a small amount of alcohol to the sucrose, which was consumed by the . The team allowed the bees to live on the alcohol-spiked sucrose for a significant period of time—long enough for them to become hooked on it. They then made the bees quit cold turkey and monitored how they behaved.

The researchers found that after the alcohol was withdrawn, the bees that worked inside the hive began eating more of the sucrose than they had before and experienced a small increase in mortality rates—an indication that they had developed a dependence on the alcohol. The researchers then resumed adding alcohol to the sucrose but in higher amounts—in some cases, increasing the alcohol concentrations to 20%. The bees reacted much like humans, exhibiting impaired locomotion and problems with foraging and learning new tasks.

The researchers also found that the bees that went out foraging had a higher tolerance for alcohol than the worker bees who remained in the hive. They suggest this indicates that the foragers had developed a resistance to as they encountered it so often as part of their job.

More information:
Monika Ostap-Chec et al, Discontinued alcohol consumption elicits withdrawal symptoms in honeybees, Biology Letters (2021). DOI: 10.1098/rsbl.2021.0182

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Honeybees show withdrawal symptoms when weaned off alcohol (2021, June 16)
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Hexbyte Glen Cove Social identity within the anti-vaccine movement thumbnail

Hexbyte Glen Cove Social identity within the anti-vaccine movement

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A study of more than 1,000 demographically representative participants found that about 22 percent of Americans self-identify as anti-vaxxers, and tend to embrace the label as a form of social identity.

According to the study by researchers including Texas A&M University School of Public Health assistant professor Timothy Callaghan, 8 percent of this group “always” self-identify this way, with 14 percent “sometimes” identifying as part of the anti-vaccine movement. The results were published in the journal Politics, Groups, and Identities.

“We found these results both surprising and concerning,” Callaghan said. “The fact that 22 percent of Americans at least sometimes identify as was much higher than expected and demonstrates the scope of the challenge in vaccinating the population against COVID-19 and other .”

Researchers also found that participants who scored high on the anti-vaccine measure were less trusting of scientific experts and more individualistic. Additionally, study results show that there is increased opposition to childhood vaccine requirements among those who self-identify as anti-vaxxers.

The study serves as a “blueprint” for other researchers to further examine how socially identifying as an anti-vaxxer impacts health policies and public health. Callaghan notes that Americans socially identifying as anti-vaxxers adds another layer of complexity to mitigating the anti-vaccine movement. Changing a core feature of one’s underlying is a difficult task—one that likely cannot be fixed with traditional messaging.

Moving forward, Callaghan and other members of the research team hope to investigate how endorsement of the anti-vaccine label varies across the country based on states and levels of rurality, as well as interventions that might reduce individuals’ social attachment to the label.

More information:
Matt Motta et al, Identifying the prevalence, correlates, and policy consequences of anti-vaccine social identity, Politics, Groups, and Identities (2021). DOI: 10.1080/21565503.2021.1932528

Social identity within the anti-vaccine movement (2021, June 4)
retrieved 5 June 2021
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