https://phys.org/news/2018-05-nanoparticles-drugs-blood-brain-barrier-glioblastoma.html

Nanoparticles carrying two drugs can cross the blood-brain barrier and shrink glioblastoma tumors

May 24, 2018 by Anne Trafton, Massachusetts Institute of Technology
Tiny particles could help fight brain cancer
MIT researchers have designed brain-tumor-targeting nanoparticles that can carry two different drugs, one in the core and one in the outer shell. Credit: Stephen Morton

Glioblastoma multiforme, a type of brain tumor, is one of the most difficult-to-treat cancers. Only a handful of drugs are approved to treat glioblastoma, and the median life expectancy for patients diagnosed with the disease is less than 15 months.

MIT researchers have now devised a new drug-delivering nanoparticle that could offer a better way to treat glioblastoma. The , which carry two different drugs, are designed so that they can easily cross the blood-brain barrier and bind directly to tumor cells. One drug damages tumor cells’ DNA, while the other interferes with the systems cells normally use to repair such damage.

In a study of mice, the researchers showed that the particles could shrink tumors and prevent them from growing back.

“What is unique here is we are not only able to use this mechanism to get across the blood-brain barrier and target tumors very effectively, we are using it to deliver this unique drug combination,” says Paula Hammond, a David H. Koch Professor in Engineering, the head of MIT’s Department of Chemical Engineering, and a member of MIT’s Koch Institute for Integrative Cancer Research.

Hammond and Scott Floyd, a former Koch Institute clinical investigator who is now an associate professor of radiation oncology at Duke University School of Medicine, are the senior authors of the paper, which appears in Nature Communications. The paper’s lead author is Fred Lam, a Koch Institute research scientist.

Targeting the brain

The nanoparticles used in this study are based on particles originally designed by Hammond and former MIT graduate student Stephen Morton, who is also an author of the new paper. These spherical droplets, known as liposomes, can carry one drug in their core and the other in their fatty outer shell.

To adapt the particles to treat brain tumors, the researchers had to come up with a way to get them across the blood-brain barrier, which separates the brain from circulating blood and prevents large molecules from entering the brain.

The researchers found that if they coated the liposomes with a protein called transferrin, the particles could pass through the blood-brain barrier with little difficulty. Furthermore, transferrin also binds to proteins found on the surface of tumor cells, allowing the particles to accumulate directly at the tumor site while avoiding healthy brain cells.

This targeted approach allows for delivery of large doses of chemotherapy drugs that can have unwanted side effects if injected throughout the body. Temozolomide, which is usually the first chemotherapy drug given to glioblastoma patients, can cause bruising, nausea, and weakness, among other side effects.

Building on prior work from Floyd and Yaffe on the DNA-damage response of tumors, the researchers packaged temozolomide into the inner core of the liposomes, and in the outer shell they embedded an experimental drug called a bromodomain inhibitor. Bromodomain inhibitors are believed to interfere with cells’ ability to repair DNA damage. By combining these two drugs, the researchers created a one-two punch that first disrupts ‘ DNA repair mechanisms, then launches an attack on the cells’ DNA while their defenses are down.

The researchers tested the nanoparticles in mice with glioblastoma tumors and showed that after the nanoparticles reach the  site, the particles’ outer layer degrades, releasing the bromodomain inhibitor JQ-1. About 24 hours later, temozolomide is released from the particle core.

The researchers’ experiments revealed that -delivering nanoparticles coated with transferrin were far more effective at shrinking tumors than either uncoated nanoparticles or temozolomide and JQ-1 injected into the bloodstream on their own. The mice treated with the transferrin-coated nanoparticles survived for twice as long as mice that received other treatments.

“This is yet another example where the combination of nanoparticle delivery with drugs involving the DNA-damage response can be used successfully to treat cancer,” says Michael Yaffe, a David H. Koch Professor of Science and member of the Koch Institute, who is also an author of the paper.

Novel therapies

In the mouse studies, the researchers found that animals treated with the targeted  experienced much less damage to blood cells and other tissues normally harmed by temozolomide. The particles are also coated with a polymer called polyethylene glycol (PEG), which helps protect the particles from being detected and broken down by the immune system. PEG and all of the other components of the liposomes are already FDA-approved for use in humans.

“Our goal was to have something that could be easily translatable, by using simple, already approved synthetic components in the liposome,” Lam says. “This was really a proof-of-concept study [showing] that we can deliver novel combination therapies using a targeted nanoparticle system across the blood-brain barrier.”

JQ-1, the bromodomain inhibitor used in this study, would likely not be well-suited for human use because its half-life is too short, but other bromodomain inhibitors are now in clinical trials.

The  anticipate that this type of nanoparticle delivery could also be used with other cancer drugs, including many that have never been tried against glioblastoma because they couldn’t get across the blood-brain barrier.

“Because there’s such a short list of drugs that we can use in brain tumors, a vehicle that would allow us to use some of the more common chemotherapy regimens in  would be a real game-changer,” Floyd says. “Maybe we could find efficacy for more standard chemotherapies if we can just get them to the right place by working around the  with a tool like this.”

 Explore further: Scientists exploit leaks in blood brain barrier to treat glioblastoma

More information: Fred C. Lam et al. Enhanced efficacy of combined temozolomide and bromodomain inhibitor therapy for gliomas using targeted nanoparticles, Nature Communications (2018). DOI: 10.1038/s41467-018-04315-4

 

https://phys.org/news/2018-05-dna.html

The changing shape of DNA

May 24, 2018, University of East Anglia
DNA
A depiction of the double helical structure of DNA. Its four coding units (A, T, C, G) are color-coded in pink, orange, purple and yellow. Credit: NHGRI

The shape of DNA can be changed with a range of triggers including copper and oxygen—according to new research from the University of East Anglia.

The structure of DNA is widely accepted to exist as a , but different DNA structures also exist. New research published today points to a range of triggers that can manipulate its shape.

Applications for this discovery include nanotechnology—where DNA is used to make tiny machines, and in DNA-based computing—where computers are built from DNA rather than silicon.

Lead researcher Dr. Zoe Waller from UEA’s School of Pharmacy said: “DNA is a genetic material, and its structure usually looks a bit like a twisted ladder—a double helix.

“But alternative DNA structures exist and are thought to potentially play a role in the development of genetic diseases, such as diabetes or cancer.”

“It was previously known that the structure of a piece of DNA could be changed using acid, which causes it to fold up into a shape called an ‘i-motif’.

“This system can be used as a switch—the DNA in the two different conditions has completely different shapes so we can recognise this as either ‘on’ or ‘off’. This has been used for DNA nano-machine applications.”

Dr. Waller’s research previously showed that the shape of DNA can also be changed into a second called a hairpin by using copper salts. This change can then be reversed using EDTA (Ethylenediaminetetraacetic acid) – an agent commonly found in shampoo and other household products.

This expanded the capability of DNA into two switches instead of one.

Her new findings show that other triggers, including oxygen and a substance similar to Vitamin C, can also trigger DNA to change its shape.

The team added copper salts to DNA in oxygen free conditions in order to change its shape to an i-motif. By exposing the i-motif to oxygen in the air, it then changed from in i-motif into a hairpin.

The shape can then be changed from a hairpin back to an i-motif by adding sodium ascorbate, which is similar to vitamin C, and back to an unfolded state using a chelating agent.

“This research means that now we can not only change the shape of DNA using a change in pH, we can use copper salts and  to have the same effect,” said Dr. Waller.

“There are many applications that this research could be used for. The potential changes in  can be used as on/off switches for logic gates in DNA computing. Our findings could also be used in nanotechnology, or to change the properties of materials such as gels,” she added.

 Explore further: How UEA research could help build computers from DNA

More information: ‘Redox Dependent Control of i-Motif DNA Structure Using Copper Cations’ Nucleic Acids Research, Friday, May 25, 2018.

 

http://www.dailymail.co.uk/sciencetech/article-5769235/Privacy-fears-woman-says-Echo-device-recorded-sent-private-conversation.html

Privacy fears after woman says Alexa recorded a private conversation and sent it to a random contact

  • Portland woman discovered her Alexa recorded and sent a private conversation
  • It was only until a contact let her know that she became aware of the flaw
  • Amazon says it’s aware of the issue and in the process of releasing a fix
  • Issue raised the ire of privacy advocates who worry Alexa is spying on its users

Be careful of what you say around your Echo devices.

A Portland woman was shocked to discover that Echo recorded and sent audio of a private conversation to one of their contacts without their knowledge, according to KIRO 7.

The woman, who is only identified as Danielle, said her family had installed the popular voice-activated speakers throughout their home.

It wasn’t until a random contact called to let them know that he’d received a call from Alexa that they realized their device had mistakenly tra

As unlikely as this string of events is, we are evaluating options to make this case even less likely’, they added.

Amazon offered to ‘de-provision’ the communication features of the woman’s Echo device so that she could continue using the smart home features.

But she said she’d much rather get a refund and says she’s dumped all her Alexa devices from her home.

‘A husband and wife in the privacy of their home have conversations that they’re not expecting to be sent to someone [in] their address book,’ she told KIRO.

A number of privacy concerns have been raised in recent months around Amazon’s Alexa-enabled speakers.

A Portland woman was shocked to discover that Echo recorded and sent audio of a private conversation to one of their contacts without their knowledge

The contact, who was one of her husband’s work employees, told the woman to ‘unplug your Alexa devices right now. You’re being hacked’, KIRO noted.

‘We unplugged all of them and he proceeded to tell us that he had received audio files of recordings from inside our house,’ Danielle said.

‘…I felt invaded. Immediately I said, “I’m never plugging that device in again, because I can’t trust it”‘, she added.

Thankfully, the recorded conversation was only about hardware floors, but the incident has still managed to spark fears of Alexa spying on its users.

 

http://www.dailymail.co.uk/sciencetech/article-5770833/Ghostly-lightning-waves-inside-nuclear-reactor-make-fusion-power-reality.html

A step towards limitless energy: ‘Ghostly’ lightning waves found inside a nuclear reactor could control electrons and make fusion power a reality

  • Department of Energy’s Oak Ridge National Laboratory made the findings
  • Whistlers waves, created by lightning, are found whipping across the ionosphere
  • They travel across the globe at heights of 620 miles (1,000km) above the planet
  • Scientists say they have detected the mysterious waves inside their reactor 
  • They could be used to help prevent runaway electrons in the fusion process
  • A breakthrough in fusion reaction technology and limitless energy could result

‘Ghostly’ whistler waves created by lightning may help to protect experimental nuclear fusion reactors and make limitless energy a reality.

That’s the claim made by a group of researchers who detected the ghostly presence of the waves inside their reactor, in what they say is a world first.

Whistlers are normally found whipping across the ionospheric layer of the Earth’s atmosphere at heights of up to 620 miles (1,000km) above the planet.

Now, scientists say they have detected the mysterious electromagnetic waves inside their reactor.

They were surprised to find that whistlers appeared to help prevent runaway electrons, produced in the nuclear fusion process.

These particles, travelling at ever faster speeds, risk burning holes in the equipment if they accelerate too fast.

Experts hope to tame this by developing methods of controls based on their findings, which could lead to a breakthrough in fusion reaction.

Scroll down for video 

Ethereal waves known as whistlers created by lightning may help to protect experimental nuclear fusion reactors  from damage. That's the claim made by a group of researchers who detected the ghostly presence of whistler waves inside their reactor (pictured)

Ethereal waves known as whistlers created by lightning may help to protect experimental nuclear fusion reactors from damage. That’s the claim made by a group of researchers who detected the ghostly presence of whistler waves inside their reactor (pictured)

Whistlers are normally found whipping across the ionospheric layer of the Earth's atmosphere at heights of up to 620 miles above the planet. Now, scientists say they have detected the mysterious electromagnetic waves inside their tokamak reactor (graphical representation)

Whistlers are normally found whipping across the ionospheric layer of the Earth’s atmosphere at heights of up to 620 miles above the planet. Now, scientists say they have detected the mysterious electromagnetic waves inside their tokamak reactor (graphical representation)

The findings were made by a research team led by the US Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL).

For decades, experts have been building the scientific basis for nuclear fusion as an energy source to generate limitless electricity.

Fusion happens when the nuclei of lighter atoms join under extraordinarily high temperatures to create a heavier nucleus, releasing energy.

The hot, fused atoms form a plasma that is confined by high magnetic fields in an experimental vessel called a tokamak – designed to withstand conditions hotter than the sun.

Strong magnetic fields are used to keep the plasma away from the reactor’s walls, so that it doesn’t cool down and lose its energy potential.

Instabilities can occur in such an extreme environment, causing a dramatic quenching, or cool down, of the plasma and producing runaway electrons that could veer off and burn holes in the tokamak’s interior wall.

Using sophisticated technologies, the team made direct measurements of whistler waves produced when a laboratory plasma becomes unstable and generates runaway electrons.

By better understanding this process, they hope they can reverse engineer it, and create whistler generating antennas to prevent electrons from getting too fast.

WHAT ARE WHISTLER WAVES AND WHAT DO WE KNOW ABOUT THEM?

Whistler waves are electromagnetic waves that originate during lightning strikes and are usually in the frequency range of 300 to 30,000 hertz.

They are sometimes detected by a sensitive audio amplifiers as a gliding high-to-low-frequency sound.

Whistlers waves last about half a second, and they may be repeated at regular intervals of several seconds, growing progressively longer and fainter with time.

Whistler waves travel through the ionosphere, which begins at a height of about 30 miles (50km) above the Earth’s surface, and reaches as high as 620 miles (1,000km).

These waves travel along ducts, or regions of enhanced ionisation, where they pass from one hemisphere to another along the Earth’s magnetic field.

They are then reflected back at the corresponding geomagnetic latitude in the opposite hemisphere.

The whistle effect occurs because the reflected high-frequency waves arrive at the amplifier before the lower-pitched signals.

Repeated reflections, dispersion, and absorption of the waves are responsible for their subsequent fainter and longer whistling tones.

Scientists have studied whistler wave propagation to determine electron density in the Earth’s atmosphere at altitudes as high as 12,000 to 16,000 miles (19,000 to 26,000 km).

They can also be used to calculate the daily, annual, and long-term variations of electron density in the upper atmosphere.

Runaway electrons also occur in nature. They are energised when lightning strikes or solar substorms disrupt the plasma environment of the Earth’s ionosphere, which is the atmosphere’s ionised upper layer.

Scientists have theorised that whistler waves regulate space weather and may help mitigate the damaging effects of energetic electrons on satellites orbiting the Earth.

‘We have known that runaway electrons drive whistler waves in the ionosphere during natural events, which led to theories that runaways would also drive similar electromagnetic waves in a tokamak plasma, said ORNL’s Don Spong who led the study.

For decades, scientists have been building the scientific basis for nuclear fusion as an energy source to generate electricity. This artist's impression shows what fusion energy generation could look like inside a tokamak reactor

For decades, scientists have been building the scientific basis for nuclear fusion as an energy source to generate electricity. This artist’s impression shows what fusion energy generation could look like inside a tokamak reactor

‘Observing whistler waves helps us better understand their underlying physical mechanisms, which could open an avenue to develop new techniques to control runaway electrons and keep them from potentially damaging fusion reactors.

‘As we learn more about the characteristics and excitation of whistler waves in tokamaks, we may be able to mimic similar behaviour to protect plasma-facing components.’

The team’s experiments took place at the DIII-D National Fusion Facility, a DOE user facility, which is operated by General Atomics in San Diego, California.

The full findings were published in the journal Physical Review Letters.

HOW DOES A NUCLEAR FUSION REACTOR WORK?

Fusion is the process by which a gas is heated up and separated into its constituent ions and electrons.

It involves light elements, such as hydrogen, smashing together to form heavier elements, such as helium.

For fusion to occur, hydrogen atoms are placed under high heat and pressure until they fuse together.

When deuterium and tritium nuclei – which can be found in hydrogen – fuse, they form a helium nucleus, a neutron and a lot of energy.

In a fusion reactor, strong magnetic fields are used to keep plasma - a gaseous soup of subatomic particles - away from the reactor's walls, so that it doesn't cool down and lose its energy potential. This graphic shows Tokamak Energy's experimental design

In a fusion reactor, strong magnetic fields are used to keep plasma – a gaseous soup of subatomic particles – away from the reactor’s walls, so that it doesn’t cool down and lose its energy potential. This graphic shows Tokamak Energy’s experimental design

This is done by heating the fuel to temperatures in excess of 150 million°C and forming a hot plasma, a gaseous soup of subatomic particles.

Strong magnetic fields are used to keep the plasma away from the reactor’s walls, so that it doesn’t cool down and lose its energy potential.

These fields are produced by superconducting coils surrounding the vessel and by an electrical current driven through the plasma.

For energy production, plasma has to be confined for a sufficiently long period for fusion to occur.

When ions get hot enough, they can overcome their mutual repulsion and collide, fusing together.

When this happens, they release around one million times more energy than a chemical reaction and three to four times more than a conventional nuclear fission reactor.

 

https://mobilesyrup.com/2018/05/24/real-time-google-lens-redesign-rollout/

Real-time Google lens features, redesign begin rolling out

Update includes new real-world copy and paste features

Google started rolling out the real-time Google Lens features it showed off at Google I/O earlier this month. Now, users can just point their phone cameras at the world. The app proactively searches for information and places small coloured dots on recognized objects. Tapping the dots load up information about the object.

A combination of on-device machine learning and the use of Google’s new cloud TPUs to identify things quickly. The smart text selection feature is also live. Users can now highlight text on objects in the real world as well as copy it and paste it. Additionally, the similar objects feature is live as well. Google Lens is capable of displaying objects that look similar to ones you’ve scanned with your phone. Along with the new features, Google Lens is sporting a new look. A round, white card now resides at the bottom of the screen.

Users can drag it up to see a list of features. When you select a recognized object, the card also pops up with the information. The redesign also moved the microphone icon to the right side of the screen. It also removed the ‘Remember this,’ ‘Important to keep’ and ‘Share’ suggestion bubbles.

Unfortunately the new features appear to be pushed out server-side. There is no app update or APK file to download that brings the new changes. As of yet, no one at MobileSyrup has received the update. It doesn’t appear to be device specific. Some users on Reddit confirmed they received the update on the Galaxy S8 and the OnePlus 5T. However, my Pixel 2 XL running the Android P beta has not received the update.

https://globalnews.ca/news/4223342/transgender-brain-scan-research/

MRI scans suggest transgender people’s brains resemble their identified gender: study

The brains of transgender individuals share characteristics with those of the gender they identify with, according to new research.

Researchers used MRI scans to identify how adolescents’ brains responded to a pheromone that men and women are known to react to differently.

The brains of transgender people who identified as women reacted more like female brains, and transgender people who identified as men had brains that responded more like males than their biological sex.

The researchers, who presented their findings Tuesday at the European Society of Endocrinology’s annual symposium, focused on the brains of adolescents who had gender dysphoria. People with gender dysphoria have a conflict between their physical or assigned gender and the gender they identify with, according to the American Psychiatric Association. This can cause them considerable distress.

READ MORE: Is the world more accepting of transgender people? Yes, but many people still aren’t, says Ipsos poll

There are sex differences in the brain at the structural level and also how male and female brains perform certain tasks, said neuroscientist Julie Bakker of the University of Liege in Belgium via email. Bakker’s research “found that adolescents with gender dysphoria had brain activity patterns very similar to their desired/experienced gender,” she wrote.

“At the moment, most available evidence suggests that it is a developmental effect, taking place before birth, but of course, we cannot rule out any effects of sex hormones later in life.”

Bakker’s study was small: looking at only about 150 individuals. As such, its findings should be interpreted with caution. Doug VanderLaan, an assistant professor of psychology at the University of Toronto, is currently working on a similar study at a larger scale, which has yet to publish results.

“This research area is still very much in its early days,” he said. “There have been relatively few studies and the methods have not been consistent. Consequently, there are few findings regarding specific brain areas that have been shown to be reliable and more research is needed.”

READ MORE: Transgender man gives birth to baby boy, says he is ‘overwhelmed with love’

However, he said, across studies so far, it has generally been the case that the brains of transgender people share certain resemblances to those of their identified gender.

“Overall, it seems there is merit to the idea that certain aspects of the brains of transgender people align with their experienced gender identity.”

Bakker suggests that her research could be used to inform how young people with gender dysphoria are treated. “Although more research is needed, we now have evidence that sexual differentiation of the brain differs in young people with GD (gender dysphoria), as they show functional brain characteristics that are typical of their desired gender,” she said.

With more research, “We will then be better equipped to support these young people, instead of just sending them to a psychiatrist and hoping that their distress will disappear spontaneously.”

VanderLaan thinks it’s a little too soon to jump to that conclusion.

“At present, MRI is not a reliable tool for determining whether a person is transgender or cisgender, and there is debate about its utility for distinguishing cisgender males and females.”

Because studies so far have focused on group averages, he said, individuals could vary considerably.

“Even if one day it were possible to use MRI to determine gender identity, I have a difficult time imagining that a care provider would give more weight to the result of a brain scan than to a person’s stated identity as transgender or cisgender.”

https://globalnews.ca/news/4230035/alexa-recorded-conversations-sent-friend-privacy/

Alexa recorded one family’s conversations and sent them to a friend, without them knowing

WATCH ABOVE: A woman in Portland said her family’s Amazon Echo recorded her conversations, then sent them to a random contact without any human direction.

If you think technology is listening to your conversation, you could be on to something.

A woman in Portland said that her family’s Amazon Echo recorded her conversations, then sent them to a random contact without any human direction.

“I felt invaded,” Danielle, who didn’t want to use her last name, told local news station KIRO7. “A total privacy invasion. Immediately I said, ‘I’m never plugging that device in again, because I can’t trust it.’”

She said she only found out about the recording when she got a phone call from the person who received the recordings, an employee of her husband’s.

“The person on the other line said, ‘Unplug your Alexa devices right now, you’re being hacked,’” she said. (Alexa is the name for the artificial intelligence program on Amazon devices like the Echo.)

READ MORE: Amazon’s Alexa is randomly laughing at people, and the company is trying to fix it

The employee – who was in Seattle, 283 kilometres away from Portland – repeated back parts of the conversation to her.

“A husband and wife in the privacy of their home have conversations that they’re not expecting to be sent to someone [in] their address book,” she said.

After unplugging the devices, which were throughout every room in her home and designed to control lights and heating, Danielle called the company to find out what happened.

An engineer with the company apologized to Danielle. He told her the device “just guessed” what her and her husband were saying.

In a report to Engadget, Amazon officials offered a more detailed explanation.

“Echo woke up due to a word in background conversation sounding like ‘Alexa.’ Then, the subsequent conversation was heard as a ‘send message’ request. At which point, Alexa said out loud ‘To whom?’ At which point, the background conversation was interpreted as a name in the customer’s contact list. Alexa then asked out loud, ‘[contact name], right?’ Alexa then interpreted background conversation as ‘right’. As unlikely as this string of events is, we are evaluating options to make this case even less likely,” officials told the technology website.

WATCH: Amazon’s Alexa looking to become a personal health tool

Danielle told KIRO7 that Alexa did not say out loud that it was sending a recording to a contact.

Amazon has offered to “de-provision” her devices from the internet, meaning they would still be able to use the Smart Home features, but it wouldn’t be able to send messages outside the home. Danielle said she would like a full refund for the devices.

“Amazon takes privacy very seriously. We investigated what happened and determined this was an extremely rare occurrence. We are taking steps to avoid this from happening in the future,” the company said in a statement.

The incident isn’t the first time Alexa has been caught doing things it wasn’t told to do. In March, people said the device was caught randomly laughing for no reason.

Another incident saw Alexa order cat food after a commercial without its owner telling it to.

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http://blog.wolfram.com/2018/05/24/learning-to-listen-neural-networks-application-for-recognizing-speech/

Learning to Listen: Neural Networks Application for Recognizing Speech

May 24, 2018 — Carlo Giacometti, Kernel Developer, Algorithms R&D

Introduction

Recognizing words is one of the simplest tasks a human can do, yet it has proven extremely difficult for machines to achieve similar levels of performance. Things have changed dramatically with the ubiquity of machine learning and neural networks, though: the performance achieved by modern techniques is dramatically higher compared with the results from just a few years ago. In this post, I’m excited to show a reduced but practical and educational version of the speech recognition problem—the assumption is that we’ll consider only a limited set of words. This has two main advantages: first of all, we have easy access to a dataset through the Wolfram Data Repository (the Spoken Digit Commands dataset), and, maybe most importantly, all of the classifiers/networks I’ll present can be trained in a reasonable time on a laptop.

It’s been about two years since the initial introduction of the Audio object into the Wolfram Language, and we are thrilled to see so many interesting applications of it. One of the main additions to Version 11.3 of the Wolfram Language was tight integration of Audio objects into our machine learning and neural net framework, and this will be a cornerstone in all of the examples I’ll be showing today.

Without further ado, let’s squeeze out as much information as possible from the Spoken Digit Commands dataset!

Spoken Digit Commands dataset

The Data

Let’s get started by accessing and inspecting the dataset a bit:

&#10005

ro=ResourceObject["Spoken Digit Commands"]

The dataset is a subset of the Speech Commands dataset released by Google. We wanted to have a “spoken MNIST,” which would let us produce small, self-enclosed examples of machine learning on audio signals. Since the Spoken Digit Commands dataset is a ResourceObject, it’s easy to get all the training and testing data within the Wolfram Language:

&#10005

trainingData=ResourceData[ro,"TrainingData"];
testingData=ResourceData[ro,"TestData"];
RandomSample[trainingData,3]//Dataset

One important thing we made sure of is that the speakers in the training and testing sets are different. This means that in the testing phase, the trained classifier/network will encounter speakers that it has never heard before.

&#10005

Intersection[trainingData[[All,"SpeakerID"]],testingData[[All,"SpeakerID"]]]

The possible output values are the digits from 0 to 9:

&#10005

classes=Union[trainingData[[All,"Output"]]]

Conveniently, the length of all the input data is between .5 and 1 seconds, with the majority for the signals being one second long:

&#10005

Dataset[trainingData][Histogram[#,ScalingFunctions->"Log"]&@*Duration,"Input"]

Encoders

In Version 11.3, we built a collection of audio encoders in NetEncoder and properly integrated it into the rest of the machine learning and neural net framework. Now we can seamlessly extract features from a large collection of audio recordings; inject them into a net; and train, test and evaluate networks for a variety of applications.

Since there are multiple features that one might want to extract from an audio signal, we decided that it was a good idea to have one encoder per feature rather than a single generic "Audio" one. Here is the full list:

• "Audio"
• "AudioSTFT"
• "AudioSpectrogram"
• "AudioMelSpectrogram"
• "AudioMFCC"

The first step (which is common in all encoders) is the preprocessing: the signal is reduced to a single channel, resampled to a fixed sample rate and can be padded or trimmed to a specified duration.

The simplest one is NetEncoder["Audio"], which just returns the raw waveform:

&#10005

encoder=NetEncoder["Audio"]
&#10005

encoder[RandomChoice[trainingData]["Input"]]//Flatten//ListLinePlot

The starting point for all of the other audio encoders is the short-time Fourier transform, where the signal is partitioned in (potentially overlapping) chunks, and the Fourier transform is computed on each of them. This way we can get both time (since each chunk is at a very specific time) and frequency (thanks to the Fourier transform) information. We can visualize this process by using the Spectrogram function:

&#10005

a=AudioGenerator[{"Sin",TimeSeries[{{0,1000},{1,4000}}]},2];
Spectrogram[a]

The main parameters for this operation that are common to all of the frequency domain features are WindowSize and Offset, which control the sizes of the chunks and their offsets.

Each NetEncoder supports the "TargetLength" option. If this is set to a specific number, the input audio will be trimmed or padded to the correct duration; otherwise, the length of the output of the NetEncoder will depend on the length of the original signal.

For the scope of this blog post, I’ll be using the "AudioMFCC" NetEncoder, since it is a feature that packs a lot of information about the signal while keeping the dimensionality low:

&#10005

encoder=NetEncoder[{"AudioMFCC","TargetLength"->All,"SampleRate"->16000,"WindowSize" -> 1024,"Offset"-> 570,"NumberOfCoefficients"->28,"Normalization"->True}]
encoder[RandomChoice[trainingData]["Input"]]//Transpose//MatrixPlot

SEE

 

http://www.kurzweilai.net/high-quality-carbon-nanotubes-made-from-carbon-dioxide-in-the-air-break-the-manufacturing-cost-barrier

High-quality carbon nanotubes made from carbon dioxide in the air break the manufacturing cost barrier

“The most valuable material ever sold”
May 24, 2018

Carbon dioxide converted to small-diameter carbon nanotubes grown on a stainless steel surface. (credit: Pint Lab/Vanderbilt University)

Vanderbilt University researchers have discovered a technique to cost-effectively convert carbon dioxide from the air into a type of carbon nanotubes that they say is “more valuable than any other material ever made.”

Carbon nanotubes are super-materials that can be stronger than steel and more conductive than copper. So despite much research, why aren’t they used in applications ranging from batteries to tires?

Answer: The high manufacturing costs and extremely expensive price, according to the researchers.*

The price ranges from $100–200 per kilogram for the “economy class” carbon nanotubes with larger diameters and poorer properties, up to $100,000 per kilogram and above for the “first class” carbon nanotubes — ones with a single wall, the smallest diameters**, and the most amazing properties, Cary Pint, PhD, an assistant professor in the Mechanical Engineering department at Vanderbilt University, explained to KurzweilAI.

A new process for making cost-effective carbon nanotubes

The researchers have demonstrated a new process for creating carbon-nanotube-based material, using carbon dioxide as a feedstock input source.

  • They achieved the smallest-diameter and most valuable CNTs ever reported in the literature for this approach.
  • They used sustainable electrochemical synthesis.***
  • A spinoff, SkyNano LLC, is now doing this with far less cost and energy input than conventional methods for making these materials. “That means as market prices start to change, our technology will survive and the more expensive technologies will get shaken out of the market,” said Pint. “We’re aggressively working toward scaling this process up in a big way.”
  • There are implications for reducing carbon dioxide in the atmosphere.****

“One of the most exciting things about what we’ve done is use electrochemistry to pull apart carbon dioxide into elemental constituents of carbon and oxygen and stitch together, with nanometer precision, those carbon atoms into new forms of matter,” said Pint. “That opens the door to being able to generate really valuable products with carbon nanotubes.” These materials, which Pint calls “black gold,” could steer the conversation from the negative impact of emissions to how we can use them in future technology.

“These could revolutionize the world,” he said.

Reference: ACS Appl. Mater. Interfaces May 1, 2018. Source: Vanderbilt University

This BCC Research market report has a detailed discussion on carbon nanotube costsGlobal Markets and Technologies for Carbon Nanotubes. Also see Energy requirements,” an open-access supplement to the ACS paper.

** “Small-diameter” in this study refers to about 10 nanometers or less. Small-diameter carbon nanotubes include few-walled (about 310 walls), double-walled, and single walled carbon nanotubes. These all have higher economic value because of their enhanced physical properties, broader appeal toward applications, and greater difficulty in synthesis compared to their larger-diameter counterparts. “Larger diameter” carbon nanotubes refer to those with outer diameter generally less than 50 nanometers, since after reaching this diameter, these materials lose the value that the properties in small diameter carbon nanotubes enable for applications.

*** The researchers used mechanisms for controlling electrochemical synthesis of CNTs from the capture and conversion of ambient CO2 in molten salts. Iron catalyst layers are deposited at different thicknesses onto stainless steel to produce cathodes, and atomic layer deposition of Al2O3 (aluminum oxide) is performed on nickel to produce a corrosion-resistant anode. The research team showed that a process called “Ostwald ripening” — where the nanoparticles that grow the carbon nanotubes change in size to larger diameters — is a key contender against producing the infinitely more useful size. The team showed they could partially overcome this by tuning electrochemical parameters to minimize these pesky large nanoparticles.

**** “According to the EPA, the United States alone emits more than 6,000 million metric tons of carbon dioxide into the atmosphere every year.  Besides being implicated as a contributor to global climate change, these emissions are currently wasted resources that could otherwise be used productively to make useful materials. At SkyNano, we focus on the electrochemical conversion of carbon dioxide into all carbon-based nanomaterials which can be used for a variety of applications. Our technology overcomes cost limitations associated with traditional carbon nanomaterial production and utilizes carbon dioxide as the only direct chemical feedstock.” — SkyNano Technologies