Underground Parks

It’s not easy to keep growing cities green when there is such a high demand for building space. But nobody wants to live in a concrete jungle, which is why a company in the US has proposed a rather unusual solution: underground parks.

Inspired by New York City’s High Line, an abandoned elevated freight railway turned urban park, “Lowline” hopes to use pioneering solar technology to repurpose a former trolley terminal into a public space.

The one-acre former trolley terminal, which was abandoned in 1948, is located in the Lower East Side of Manhattan, an area which is considered “one of the least green areas of New York City,” according to Lowline’s website. Despite long-term neglect, the site has maintained some interesting features, such as old cobblestones and rail tracks, some of which Lowline plan to keep as a way of showcasing the history of the site.

The idea behind Lowline is to not only provide more green space, but to demonstrate how innovative solar technology can be used to transform cities. Alongside providing residents with a pleasant area to relax in and escape from the hustle and bustle of the city, the park will host a variety of cultural events, art exhibitions and youth activities.

To illuminate the underground area and feed all of those plants and trees, street-level reflective parabolas will be used to collect sunlight and direct it underground via fiber-optic cables. The light will then be dispersed through the park by aiming it towards reflective dishes. The solar collectors will be positioned in areas that receive lots of sunlight, and will be adjustable so that they can follow the sun as it moves, maximizing the amount of light that can be collected. When insufficient sunlight is available, electricity would be used to light up the park instead.

The project comes with a $60 million price tag, which will mostly come from private investors, although the government has agreed to fork out some cash, too. So far, over $1 million has been raised for research and design.

Construction is anticipated to commence in around five years’ time, but first Lowline needs to overcome some technical hurdles, such as working out the best way to channel the collected sunlight underground. 

polymer blend conductor

While plastics have become an indispensable material in modern society, they are not very useful for certain applications because of how heat doesn't disappate from them easily. However, a group of material scientists have developed a polymer blend that not only exceeds the heat dissipation of other plastics, but is about ten times more efficient than conventional materials like metal and ceramic as well. The project was led by Kevin Pipe of the University of Michigan, and the paper was published in Nature Materials. 

Plastics are synthetic polymers that are composed of repeating molecule chains. They are generally more lightweight and resilient than metals and glass, but the molecular arrangement does not allow heat to be removed easily when it is needed, like in automobiles and computers. Previous attempts to make a polymer blend that fits the bill have been adulterated with other materials, which detracts from the appearance and utility of the material.

"Researchers have paid a lot of attention to designing polymers that conduct electricity well for organic LEDs and solar cells, but engineering of thermal properties by molecular design has been largely neglected, even though there are many current and future polymer applications for which heat transfer is important," Pipe said in a press release. 

Plastic devices tend to trap heat, which is not desirable for uses like in smartphones. Heat energy needs strong and stable pathways to travel and dissipate, but the connections of most polymer chains tend to be too weak to transfer heat efficiently.

"The polymer chains in most plastics are like spaghetti," Pipe explained. "They're long and don't bind well to each other. When heat is applied to one end of the material, it causes the molecules there to vibrate, but these vibrations, which carry the heat, can't move between the chains well because the chains are so loosely bound together."

Pipe's team manipulated the hydrogen bonding patterns by blending short stands of polyacryloyl piperidine (PAP) with a series of other polymers known to conduct heat well in order to create amorphous polymers. Ultimately, PAP blended with long chains of polyacrylic acid (PAA) produced the strongest result, with hydrogen bonds between 10 to 100 times stronger than traditional plastics. These strong bonds produced a better route for heat transfer.

"We improved those connections so the heat energy can find continuous pathways through the material," co-author Jinsang Kim explained. "There's still a long way to go, but this is a very important step we made to understand how to engineer plastics in this way. Ten times better is still a lot lower heat conductivity than metals, but we've opened the door to continue improving."

It's important to point out the PAP/PAA blend by Pipe's team uses conventional MANUFACTURING techniques. The ability to easily mass-produce the material is integral to facilitating its widespread use. With further development, amorphous polymers like this one could potentially be used to replace metal components in computers, automobiles, and aircraft. This could make the devices more lightweight, and increase efficiency.

Earth Shield

Some 7,200 miles above Earth, an invisible shield cloaking our planet is helping to protect us from damaging, super-fast “killer” electrons, scientists have found. This Star Trek style shield stops these whizzing electrons in their tracks, preventing them from harming astronauts and frying our satellites.

As described in the journal Nature, this invisible barrier is located within the Van Allen radiation belts. These are two doughnut-shaped rings around our planet that extend up to 40,000 kilometers above Earth. The inner zone is full of high-energy protons, whereas the outer zone is dominated by high-energy electrons.

The protective shield was discovered after scientists from the University of Colorado Boulder analyzed almost two years of data gathered by the twin NASA spacecraft, the Van Allen Probes, which orbit the rings to observe the behavior of high-energy electrons in this area.

The data revealed a sharp boundary at the very inner edge of the outer belt that appeared to be deflecting incoming highly charged electrons, called ultrarelativistic electrons. These particles whizz around Earth at near light-speed, travelling at approximately 160,000 kilometers per second. It was assumed that these electrons would make a smooth transition, gradually drifting into the upper atmosphere before being destroyed by collisions with air molecules. However, much to their surprise, a sharp cutoff was observed instead.

“It’s almost like these electrons are running into a glass wall in space,” lead author Professor Daniel Baker said in a news-release. “Somewhat like the shields created by force fields on Star Trek that were used to repel alien weapons, we are seeing an invisible shield blocking these electrons. It’s an extremely puzzling phenomenon.”

To attempt to identify this enigmatic force field, the researchers examined several different scenarios that could generate and maintain a barrier of this kind. They considered that the Earth’s magnetic field lines could be somehow trapping the electrons in place, or that radio signals from human devices on Earth could be somehow dispersing the electrons. But with what they were seeing, neither of these explanations made sense.

Instead, they suggest that a cloud of cold, electrically charged gas known as the plasmasphere could be playing a role.  This giant cloud starts just 600 miles above Earth but stretches thousands of miles into the outer, high-energy electron dominated zone of the Van Allen belt. They propose that low frequency electromagnetic waves within the cloud which produce a phenomenon known as “plasmaspheric hiss” could be scattering the electrons at the boundary.

However, the team doesn’t think that the story ends there, and expects to find more pieces to the puzzle in the future. “I think the key here is to keep observing the region in exquisite detail,” said Baker, “which we can do because of the powerful instruments on the Van Allen probes.” 

[Via University of Colorado Boulder, Nature, Tech Times and LA Times]

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Two never-before-seen particles

Two never-before-seen particles have just been detected at CERN’s Large Hadron Collider, the world’s largest particle accelerator, by the international LHCb collaboration. Known as Xi_b'- and Xi_b*-, the new particles belong to the baryon family. 

Baryons are made from three fundamental, subatomic particles called quarks, bound together by a strong force. The more familiar protons and neutrons are also baryons -- these combine with electrons to make up everything on the periodic table. “The building blocks of all known things, including cars, planets, stars and people, are quarks and electrons, which are tied together by strong, electromagnetic forces,” Steven Blusk of Syracuse University explains in a news release.

And the quarks in these newly discovered baryons aren’t even the same type: Each of the new particles contains one beauty (b), one strange (s), and one down (d) quark.

The new particles are more than six times as massive as a proton, thanks to their heavyweight b quarks and their angular momentum -- a particular attribute of quarks known as “spin.” In the Xi_b'- state, the spins of the two lighter quarks point in the opposite direction to the b quark, and in the Xi_b*- state, the spins are aligned. This difference in configuration makes Xi_b*- a little heavier.

“Nature was kind and gave us two particles for the price of one," says Matthew Charles of the CNRS's LPNHE laboratory at Paris VI University in a CERN statement. "The Xi_b'- is very close in mass to the sum of its decay products: If it had been just a little lighter, we wouldn't have seen it at all using the decay signature that we were looking for.” But thanks to the sensitivity and precision of the LHCb detector, Blusk adds, “we’ve been able to separate a clean, strong signal from the background.” 

In addition to the masses of the new particles, the team also studied their relative production rates, their widths (a measurement of how unstable they are), and a few other details of their decays. The new baryons are very short-lived, CBC explains, lasting only a thousandth of a billionth of a second before breaking up into five smaller pieces. 

The existence of these particles were previously predicted in 2009, but no one has ever seen them until now. Right after the findings were released online this week, "I saw the title [and] I thought, 'Oh, I predicted those -- I wonder how it turned out?" Randy Lewis of York University tells CBC. "I looked up their numbers and I said, 'Yeah, that looks a lot like what I predicted -- great!" Lewis and colleagues predicted the mass and composition of the new particles based on mathematical rules for how quarks behave. 

Quasars

Quasars (/ˈkweɪzɑr/) or quasi-stellar radio sources are the most energetic and distant members of a class of objects called active galactic nuclei (AGN). Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that appeared to be similar tostars, rather than extended sources similar to galaxies. Their spectra contain very broad emission lines, unlike any known from stars, hence the name "quasi-stellar". Their luminosity can be 100 times greater than that of the Milky Way.Quasars separated by billions of light-years are lined up in a mysterious way. Astronomers looking at nearly 100 quasars have discovered that the central black holes of these ultra-bright, faraway galaxies have rotational axes that are aligned with each other. These alignments are the largest known in the universe.
Quasars are some of the brightest things known, and at the center of these super luminous nuclei of galaxies are very active supermassive black holes. The black hole is surrounded by a spinning disc of extremely hot material, which gets spewed out in long jets all along the quasar’s axis of rotation.
Using the European Southern Observatory’s Very Large Telescope in Chile, a team led byDamien Hutsemékers from the University of Liège in Belgium studied 93 quasars known to form huge groupings. We’re seeing them now at a time when the universe was only about a third of its current age. “The first odd thing we noticed was that some of the quasars’ rotation axes were aligned with each other—despite the fact that these quasars are separated by billions of light-years,” Hutsemékers says in a news release.
So the team wanted to find out if the rotation axes were linked at that time—and not just to each other, but also to the structure of the universe on large scales. When looking at the distribution of galaxies on scales of billions of light-years, astronomers have found that galaxies aren’t evenly distributed: They form a web of filaments and clump around huge galaxy-scarce voids. This arrangement of material is known as the large-scale structure.
The team could not see the rotation axes or the jets of the quasars directly. Instead they measured the polarization of the light from each quasar and found a significantly polarized signal for 19 of them. The direction of this polarization helps to deduce the angle of the disc and the direction of the spin axis of the quasar.
These new findings indicate that the rotation axes of quasars tend to be parallel to the large-scale structures that they inhabit. That means that if the quasars are in a long filament, then the spins of their central black holes will point along the filament. (See the image above.) According their estimates, there’s only a one percent probability that these alignments are simply the result of chance.
“A correlation between the orientation of quasars and the structure they belong to is an important prediction of numerical models of evolution of our universe,” says study co-author Dominique Sluse of the Argelander-Institut für Astronomie in Bonn, Germany. “The alignments in the new data, on scales even bigger than current predictions from simulations, may be a hint that there is a missing ingredient in our current models of the cosmos.”
The findings were published in the journal Astronomy & Astrophysics this week. Here’s a detailed simulation of the large-scale structure centered on a massive galaxy cluster. The distribution of dark matter is shown in blue, the gas distribution in orange. The region shown is about 300 million light-years across.

Books Collection, Physics Department, MAO College Lahore .

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There are almost no limits when collecting books from internet. A good book focuses on a certain topic and covers it as well as possible. So far, I had collected some book which may help physics students in their extra studies. ( Click on One Drive link to open folder)