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Light is notoriously fast. Its speed is crucial for rapid information exchange, but as light zips through materials, its chances of interacting and exciting atoms and molecules can become very small. If scientists can put the brakes on light particles, or photons, it would open the door to a host of new technology applications.

Now, in a paper published in Nature Nanotechnology, Stanford scientists demonstrate a new approach to slow light significantly, much like an echo chamber holds onto sound, and to direct it at will. Researchers in the lab of Jennifer Dionne, associate professor of materials science and engineering at Stanford, structured ultrathin silicon chips into nanoscale bars to resonantly trap light and then release or redirect it later. These “high-quality-factor” or “high-Q” resonators could lead to novel ways of manipulating and using light, including new applications for quantum computing, virtual reality and augmented reality; light-based WiFi; and even the detection of viruses like SARS-CoV-2.

Stanford scientists slow and steer light with resonant nanoantennas

An artist rendering of a high-Q metasurface beamsplitter. These “high-quality-factor” or “high-Q” resonators could lead to novel ways of manipulating and using light. Image credit: Riley A. Suhar

“We’re essentially trying to trap light in a tiny box that still allows the light to come and go from many different directions,” said postdoctoral fellow Mark Lawrence, who is also lead author of the paper. “It’s easy to trap light in a box with many sides, but not so easy if the sides are transparent – as is the case with many Silicon-based applications.”

Make and manufacture

Before they can manipulate light, the resonators need to be fabricated, and that poses a number of challenges.

A central component of the device is an extremely thin layer of silicon, which traps light very efficiently and has low absorption in the near-infrared, the spectrum of light the scientists want to control. The silicon rests atop a wafer of transparent material (sapphire, in this case) into which the researchers direct an electron microscope “pen” to etch their nanoantenna pattern. The pattern must be drawn as smoothly as possible, as these antennas serve as the walls in the echo-chamber analogy, and imperfections inhibit the light-trapping ability.

“High-Q resonances require the creation of extremely smooth sidewalls that don’t allow the light to leak out,” said Dionne, who is also Senior Associate Vice Provost of Research Platforms/Shared Facilities. “That can be achieved fairly routinely with larger micron-scale structures, but is very challenging with nanostructures which scatter light more.”

Pattern design plays a key role in creating the high-Q nanostructures. “On a computer, I can draw ultra-smooth lines and blocks of any given geometry, but the fabrication is limited,” said Lawrence. “Ultimately, we had to find a design that gave good-light trapping performance but was within the realm of existing fabrication methods.”

High quality (factor) applications

Tinkering with the design has resulted in what Dionne and Lawrence describe as an important platform technology with numerous practical applications.

The devices demonstrated so-called quality factors up to 2,500, which is two orders of magnitude (or 100 times) higher than any similar devices have previously achieved. Quality factors are a measure describing resonance behavior, which in this case is proportional to the lifetime of the light. “By achieving quality factors in the thousands, we’re already in a nice sweet spot from some very exciting technological applications,” said Dionne.

For example, biosensing. A single biomolecule is so small that it is essentially invisible. But passing light over a molecule hundreds or thousands of times can greatly increase the chance of creating a detectable scattering effect.

Dionne’s lab is working on applying this technique to detecting COVID-19 antigens – molecules that trigger an immune response – and antibodies – proteins produced by the immune system in response. “Our technology would give an optical readout like the doctors and clinicians are used to seeing,” said Dionne. “But we have the opportunity to detect a single virus or very low concentrations of a multitude of antibodies owing to the strong light-molecule interactions.” The design of the high-Q nanoresonators also allows each antenna to operate independently to detect different types of antibodies simultaneously.

Though the pandemic spurred her interest in viral detection, Dionne is also excited about other applications, such as LIDAR – or Light Detection and Ranging, which is laser-based distance measuring technology often used in self-driving vehicles – that this new technology could contribute to. “A few years ago I couldn’t have imagined the immense application spaces that this work would touch upon,” said Dionne. “For me, this project has reinforced the importance of fundamental research – you can’t always predict where fundamental science is going to go or what it’s going to lead to, but it can provide critical solutions for future challenges.”

This innovation could also be useful in quantum science. For example, splitting photons to create entangled photons that remain connected on a quantum level even when far apart would typically require large tabletop optical experiments with big expensive precisely polished crystals. “If we can do that, but use our nanostructures to control and shape that entangled light, maybe one day we will have an entanglement generator that you can hold in your hand,” Lawrence said. “With our results, we are excited to look at the new science that’s achievable now, but also trying to push the limits of what’s possible.”

Source: Stanford University




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Facebook, Twitter Arbitrarily Censuring ‘Nationalistic’ Content: Tejasvi Surya

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BJP member Tejasvi Surya on Wednesday raised the issue of social media platforms like Twitter and Facebook allegedly arbitrarily censuring content posted by users, especially those with a “nationalistic approach” and sought government intervention for protection of such content.

Raising the issue during Zero Hour in Lok Sabha, Surya said for a long time there have been many “credible” allegations made against Twitter, Facebook and their affiliates of “arbitrary and unilateral regulation and censuring” of content posted by third party users, especially those with a “nationalistic approach”.

“This poses a significant constitutional challenge not only on the grounds of unreasonable restriction of free speech but also amounts to illegal interference during elections,” he said.

The MP said Facebook, Twitter and similar platforms claim themselves to be intermediaries within the meaning of the term under the IT Act, 2000.

He said the key element of this definition is that the role of the said intermediaries is limited to processing, storing and transmitting data of third party users and does not include intervention on content of the users.

Therefore, Section 79 of the Act provides these intermediaries exemption from liability. An intermediary receives protection that a regular publisher does not receive, he said.

Surya said while this is the explicit spirit of the statute, the Information Technology (Intermediary Guidelines) Rules, while laying down what sort of third party content must be prohibited by the privacy policy and terms and conditions of the intermediary, goes far beyond the remit of Article 19(2) of the Constitution read with Section 79 and 69 of the IT Act.

Article 19(2) of the Constitution authorises the government to impose, by law, reasonable restrictions upon the freedom of speech and expression “in the interests of… public order”, whereas section 69 of the IT Act allows the government to intercept any information and ask for information decryption.

Surya said the guidelines essentially empower private party intermediaries to remove on the basis of user complaints or suo moto any content deemed to be in violation of its guidelines.

He said these guidelines are not only ultra vires the parent statute but also unconstitutional as the grounds they provide are too wide and will fail the standards of constitutionality set out by the Supreme Court in the Shreya Singhal case while striking down Sec 66A of the IT Act (which provided police the power to arrest a person for posting “offensive” content online).

The guidelines are problematic because they empower private enterprises performing essentially a public function to act as censors of free speech without government oversight, thus effectively and severely impacting safeguards of the fundamental right to free speech, he said.

“I therefore urge the government to repeal such unconstitutional guidelines and issue new ones to govern social media platforms, thereby protecting the fundamental right to free speech of our citizens and protect our democracy from foreign interference,” he said.


Are Apple Watch SE, iPad 8th Gen the Perfect ‘Affordable’ Products for India? We discussed this on Orbital, our weekly technology podcast, which you can subscribe to via Apple Podcasts, Google Podcasts, or RSS, download the episode, or just hit the play button below.

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Google adds a COVID-19 layer to Maps app to show health status at county and state levels

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The new layer is color-coded, includes a count of new cases per 100,000 people, and indicates whether the count is going up or down.

A new layer in Google maps shows coronavirus case levels at the county and state levels.

Google Maps now has a COVID-19 layer that tracks how cases are trending at a county level on the mobile version of the app. You can see how cases are increasing or decreasing in your area as well as any places you may be visiting.

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Google Maps added a COVID-19 data layer to the mobile app.

To see COVID-19 data for a particular location, tap the layers button on the top right-hand corner and click on COVID-19 Info. You’ll see a number and “increasing” or “decreasing.” 

SEE: COVID-19 workplace policy (TechRepublic Premium)

This number is the seven-day average for the number of new cases per 100,000 people. The layer’s colors indicate:

  • Grey: Less than 1 case
  • Yellow: 1-10 cases
  • Orange: 10-20 cases
  • Dark orange: 20-30 cases
  • Red: 30-40 cases
  • Dark red: 40+ cases

This count includes both confirmed and probable cases in some locations. Probable cases are identified by public health officials and use criteria developed by government authorities. Some areas may not have data because local authorities haven’t published data or haven’t done so recently.

If you zoom out to the state level on a map of the US, there is a count for each state and an increasing or decreasing indicator with a matching color code.

In Europe, there is more data for some countries than others. Germany is gray, and the COVID-19 map layer shows data for individual states within the country. In France, there is data at the country level only with a rate of 14.8 cases per 100,000 which is increasing. Most of Asia is gray. 

The data comes from these sources:

  • Wikipedia
  • The New York Times
  • Johns Hopkins University CSSE COVID-19 Data
  • Brihanmumbai Municipal Corporation

The Kaiser Family Foundation lists 34 states as coronavirus hotspots. Utah’s positivity rate is 9.1% with a 104.5% change in cases over the last 14 days. If you zoom in to the county level, you can see that Utah County (65.5, increasing) is in worse shape than Salt Lake County (28, increasing). Many of the state’s rural areas are gray and show few cases. Overall the state is light orange.

In June, Google Maps added more information about transit conditions to help travelers avoid crowded metro and train stations. When you look up public transit directions for a trip, the recommended routes show relevant alerts from local transit agencies. These alerts can help you prepare accordingly if government mandates impact transit services or require you to wear a mask on public transportation. Transit alerts rolled out in Argentina, Australia, Belgium, Brazil, Colombia, France, India, Mexico, Netherlands, Spain, Thailand, United Kingdom and the U.S. where we have information from local transit agencies. 

This update also included driving alerts about COVID-19 checkpoints and restrictions along certain routes, such as national borders (starting first in Canada, Mexico, and the US). Maps users see an alert on the directions screen and after starting navigation if the route is impacted by these restrictions. 

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Immune Protein IL-17A Responsible for Lethal Side Effects of Gastric Cancer

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The formation of scar tissue, or fibrosis, as gastric cancer disseminates throughout the peritoneum can be more lethal than the cancer itself and can interfere with chemotherapy. Researchers from Kanazawa University have now found that proinflammatory cytokine IL-17A from mast cells heavily influences the degree of fibrosis and causes structural changes in peritoneal cells. Preventing mast cells from releasing IL-17A may therefore be a promising treatment strategy for gastric cancer patients with peritoneal dissemination.

Immune Protein IL 17A Responsible for Lethal Side Effects of Gastric

Fig. 2 Expression of FAP was found in HPMCs treated with IL-17A using immunofluorescence staining. This means HPMCs were transformed into myofibroblast, so called CAF, by IL-17A. FAP: fibroblast activation protein as a marker of CAF. HPMCs: human peritoneal mesothelial cells. CAF: cancer associated fibroblast. Image credit: Kanazawa University

Gastric cancer, one of the leading causes of cancer-associated mortality worldwide, is renowned for its ability to disseminate throughout the peritoneal cavity. As well as causing secondary tumors in other organs, metastatic gastric cancer cells trigger extensive stromal fibrosis, or the formation of scar tissue, that can be more deadly than the cancer itself—bowel obstruction and hydronephrosis and jaundice are all common side effects of gastric cancer-associated fibrosis. What’s more, the densely packed scar tissue can disturb chemotherapy drugs from reaching their target due to intra-tumoral high pressure.

Preventing fibrosis could therefore improve the prognosis for gastric cancer patients. The problem is, researchers have yet to discover what causes fibrosis, let alone how to prevent it.

But in a study published recently in Gastric Cancer, researchers from Kanazawa University found that an inflammatory protein produced by mast cells, IL-17A, triggers cellular changes in the peritoneum, leading to stromal fibrosis in gastric cancer patients.

Lead author Katsuya Gunjigake from Kanazawa University’s Division of Cancer Medicine explains why the researchers targeted IL-17A.

“Over-stimulation of the immune system by IL-17A plays a major role in chronic inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. It has also been associated with increased tumor growth and dissemination in various forms of cancer. Interestingly though, while studies had shown that IL-17A causes fibrosis in both Crohn’s disease and lung disease, no one had investigated the link between tissue fibrosis and IL-17A in cancer.”

By studying cancerous tissue from 70 gastric cancer patients with peritoneal dissemination, the researchers discovered that the degree of fibrosis was governed by the amount of IL-17A, and that IL-17A was being produced by a subgroup of white blood cells called mast cells.

Says Gunjigake, “Mast cells are most commonly associated with anaphylaxis but are also involved in pathogen defense and immune tolerance, among other things. They contain small particles called granules that are filled with molecules such as histamine, serotonin, and IL-17A that are released into the extracellular environment in a process known as degranulation.”

Immune Protein IL 17A Responsible for Lethal Side Effects of Gastric

Fig. 1 The number of IL-17A and MCT double positive cells correlated with the ratio of fibrotic area in the peritoneal tumors. This means IL-17A derived from mast cells may contribute tumor fibrosis. MCT: mast cell tryptase Fig. 2 Expression of FAP was found in HPMCs treated with IL-17A using immunofluorescence staining. This means HPMCs were transformed into myofibroblast, so called CAF, by IL-17A. FAP: fibroblast activation protein as a marker of CAF. HPMCs: human peritoneal mesothelial cells. CAF: cancer associated fibroblast. Fig. 3 Nude mouse was inoculated with human gastric cancer cell line MKN45-P cells intraperitoneally at day 0. Recombinant mouse IL-17A was administrated intraperitoneally at day 1, 3 and 7. Large and many peritoneal nodules were found at day 14. Fig. 4 Fibrosis in the peritoneal nodules was recognized as blue area by azan staining. Fibrous area in the tumor treated with IL-17A was wider than that without IL-17A. Image credit: Kanazawa University

The researchers then injected mice with human peritoneal cells and gastric cancer cells and examined the effects of IL-17A treatment, with interesting results.

“Not only did IL-17A increase tumor size and the degree of fibrosis, it also changed the structure of the peritoneal cells, enhancing their invasive and migratory capabilities,” explains responsible author Sachio Fushida.

“Given the obvious role of IL-17A in driving fibrosis, our results suggest that suppression of mast cell degranulation may be a promising treatment strategy for gastric cancer patients with peritoneal dissemination.”

Article

Interleukin-17A derived from mast cells contributes to fibrosis in gastric cancer with peritoneal dissemination

Journal: Gastric Cancer

Authors: Katsuya Gunjigake, Jun Kinoshita, Takahisa Yamaguchi, Hiroto Saito, Daisuke Fujimori, Toshihide Horiike, Shinichi Harada, Hidehiro Tajima, Itasu Ninomiya, Tetsuo Ohta, Sachio Fushida

DOI: 10.1007/s10120-020-01092-2

Funder

This work was supported by JSPS KAKENHI Grant Number 16K10494.

Source: Kanazawa University




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