Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Topics - Mahiuddin Ahmed

Pages: [1]
Science and Information / What is Nanotechnology?
« on: April 04, 2017, 08:47:03 PM »
Nanotechnology is science, engineering, and technology conducted at the nano-scale, which is about 1 to 100 nanometers. Nanotechnology (sometimes shortened to "nanotech") is the manipulation of matter on an atomic, molecular, and supramolecular scale.

  • Atoms and molecule computing
  • High spatial resolution spectroscopies under SPM probe
  • Graphene and 2D materials
  • Low dimensional materials (nanowires, clusters, quantum dots, etc)
  • Nanobiotechnologies & Nanomedicine
  • NanoChemistry
  • Nanofabrication tools & nanoscale integration
  • Nanomagnetism and Spintronics
  • Nanomaterials for Energy
  • NanOptics / NanoPhotonics / Plasmonics / Nanophononics
  • Nanostructured and nanoparticle based materials
  • Nanotechnologies for Security & Defense

Instead of processing information the way existing systems do, relying on bits of 0s and 1s operating on miniature transistors, quantum computers use quantum bits (or qubits) that can both be a 0 or a 1 at the same time.
Click here to see full article....

Science and Information / How Quantum Computers Are Different
« on: April 04, 2017, 08:17:26 PM »
The building blocks of quantum computers are not bits and transistors. They are qubits and physical components so small they operate by the rules of quantum physics. Qubits sharing mixed states speeds up computation—this is how they perform multiple calculations at once—it is absolutely essential the qubit maintain coherence during the calculation. Otherwise, we are just using a simple, slow digital computer only performing one calculation at a time.
Click here for full article...

A breakthrough in nanotechnology by 10 Bengaluru physicists may open up a new window to look at the creation of quantum computers in the future.
Considered the Holy Grail of computing, quantum computing has been a subject of intense theoretical research for close to four decades.
But so far no one has been able to develop a quantum computer – considered to be way above modern computers – because of several practical difficulties in building such a machine.
The Indian Institute of Science (IISc) team has now demonstrated how at least one of the critical problems in making the futuristic machine can be overcome.
Click for full article..

Very clear explanation about the concept of quantum computer.

Astronomy / A Mysterious Flash From a Faraway Galaxy
« on: April 04, 2017, 07:54:46 PM »
It was a spark in the night. A flash of X-rays from a galaxy hovering nearly invisibly on the edge of infinity.
Astronomers say they do not know what caused it.
The orbiting Chandra X-ray Observatory, was in the midst of a 75-day survey of a patch of sky known as the Chandra Deep Field-South, when it recorded the burst from a formerly quiescent spot in the cosmos.

নদী পথে যারা যাবেন তাদের ভরসা লঞ্চ। অনেক দিন পর যারা বাড়ি যাবেন তাদের অনেকেই টিকিট কাটা ও সিডিউল মেলানো নিয়ে ঝামেলায় থাকেন। তাদের এবার আর খুব বেশি দৌঁড়ঝাঁপ করতে হবে না।
হাতে একটা স্মার্টফোন থাকলে ও ‘লঞ্চঘড়ি’ নামের অ্যাপ্লিকেশন থাকলে লঞ্চের সূচী নিয়ে ঝামেলা থাকবে না।
অ্যাপ্লিকেশনটি তৈরি করেছেন মো. ইমরান হোসেন। পড়াশুনা করছেন ড্যাফোডিল ইন্টারন্যাশনাল ইউনিভার্সিটির কম্পিউটার প্রকৌশল বিভাগে
বর্তমানে একটি দেশীয় সফটওয়্যার প্রতিষ্ঠানে কর্মরত এ ডেভেলপারের বাড়ি চাঁদপুর বলেই লঞ্চ নিয়ে তার আগ্রহ বেশি।
অ্যাপটি তৈরি করতে প্রায় এক মাসের মত সময় লেগেছে। এ অ্যাপের আইডিয়া নিয়ে অনেকদিন ধরে কাজ করেছেন।
অ্যাপ তৈরির উদ্দেশ্য সম্পর্কে এমরান বলেন, এখন প্রায় সবার কাছেই স্মার্টফোন আছে। লঞ্চ ও যাত্রাীর সংখ্যাও বাড়ছে । তাই এতগুলো লঞ্চের তথ্য সবার জানার কথা না। এজন্য সব তথ্য এক সঙ্গে করতে অ্যাপটি বানিয়েছেন তিনি।

এক নজরে অ্যাপ্লিকেশনটির ফিচারগুলো
এটিতে বিভাগ ও ক্যাটাগরি অনুযাযী প্রতিটি স্থান থেকে লঞ্চের সময়সূচী দেয়া আছে।
লঞ্চের বিভিন্ন কেবিন বা ডেকের ভাড়া কত তা জানা যাবে অ্যাপটি থেকে।
লঞ্চ যাত্রা পথে অ্যাপটি ব্যবহার করে গুগল ম্যাপের সাহায্যে বর্তমান অবস্থান সম্পর্কে জানা যাবে।
অ্যাপের এ সংস্করণে বিভিন্ন রুটের সর্বমোট ৩৯টি লঞ্চের বিস্তারিত তথ্য দেওয়া হয়েছে। ধারাবাহিকভাবে তা আপডেট করা হবে।
অ্যাপের মাধ্যমে নির্ধারিত লঞ্চের সময় অনুযায়ী অ্যালার্ম দেয়া যাবে। ফলে লঞ্চের টাইম ভুলে যাওয়া সম্ভাবনা নেই।
এটি থেকে সরাসরি লঞ্চের কর্মকতাদের ফোন করা যাবে।
এটি সম্পূর্ণ অফলাইনে কাজ করবে। তাই একবার ডাউনলোডের পর ব্যবহার করতে ইন্টারনেট সংযোগ লাগবে না। তবে ম্যাপিং ফিচারটি ব্যবহার করতে ইন্টারনেট সংযোগ লাগবে।
৬.৪ মেগাবাইটের অ্যাপ্লিকেশনটির বিনামূল্যে এ ঠিকানা থেকে ডাউনলোড করে ব্যবহার করা যাবে।

Science and Information / The Nobel Prize in Physics 2016
« on: October 08, 2016, 12:31:15 PM »
The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2016 with one half to David J. Thouless University of Washington, Seattle, WA, USA and the other half to F. Duncan M. Haldane Princeton University, NJ, USA and J. Michael Kosterlitz Brown University, Providence, RI, USA

”for theoretical discoveries of topological phase transitions and topological phases of matter”

This year’s Laureates opened the door on an unknown world where matter can assume strange states. They have used advanced mathematical methods to study unusual phases, or states, of matter, such as superconductors, superfluids or thin magnetic films. Thanks to their pioneering work, the hunt is now on for new and exotic phases of matter. Many people are hopeful of future applications in both materials science and electronics.

The three Laureates’ use of topological concepts in physics was decisive for their discoveries. Topology is a branch of mathematics that describes properties that only change step-wise. Using topology as a tool, they were able to astound the experts. In the early 1970s, Michael Kosterlitz and David Thouless overturned the then current theory that superconductivity or suprafluidity could not occur in thin layers. They demonstrated that superconductivity could occur at low temperatures and also explained the mechanism, phase transition, that makes superconductivity disappear at higher temperatures.

In the 1980s, Thouless was able to explain a previous experiment with very thin electrically conducting layers in which conductance was precisely measured as integer steps. He showed that these integers were topological in their nature. At around the same time, Duncan Haldane discovered how topological concepts can be used to understand the properties of chains of small magnets found in some materials.

We now know of many topological phases, not only in thin layers and threads, but also in ordinary three-dimensional materials. Over the last decade, this area has boosted frontline research in condensed matter physics, not least because of the hope that topological materials could be used in new generations of electronics and superconductors, or in future quantum computers. Current research is revealing the secrets of matter in the exotic worlds discovered by this year’s Nobel Laureates.

What are phase transitions?
Phase transitions refer to abrupt changes in the properties of a material - for instance the progression from ice to water to steam as the temperature is ramped up from freezing. However, as well as the traditional states of solid, liquid, gas, Thouless, Haldane and Kosterlitz (and others) showed that materials also make sudden transitions in their electrical properties. This might manifest itself as a sudden drop in the electrical resistance of a material as it is cooled down. So-called topological phase transitions were initially investigated in materials with thin layers, or ones that formed thin threads, but now scientists have shown that “exotic” electrical properties can be found in a wide range of materials.

When hundreds of engineers and builders began clambering up a jagged hill in southwestern China to assemble a giant telescope in a deep, bowl-shaped basin, poor villagers sometimes crept over the sheer slopes to glimpse the country’s latest technological wonder.
“We’ve never seen anything like it, never imagined it,” said one villager, Huang Zhangrong, a sun-gnarled 66-year-old carpenter. “It’s a big circle, a big iron wok.”
The wok is the world’s largest single-dish radio telescope, and it officially began operating on Sunday, accompanied by jubilant national television coverage, after more than five years of construction. The Five-hundred-meter Aperture Spherical Telescope, FAST for short, is intended to project China’s scientific ambitions deep into the universe, bringing back dramatic discoveries and honors like Nobel Prizes.
Maybe even messages from aliens.
The telescope, which is in a majestic but impoverished part of Guizhou Province, embodies China’s plans to rise as a scientific power. The dish is made of 4,450 intricately positioned triangular panels and has a collecting area of 2.1 million square feet, equal to almost 450 basketball courts. At 1,640 feet in diameter, it will be roughly twice as sensitive as the world’s next-biggest single-dish radio telescope, the Arecibo Observatory in Puerto Rico, which is 1,000 feet across.
The telescope will help China make “major advances and breakthroughs at the frontier of science,” President Xi Jinping of China said in a congratulatory message on Sunday. He called it China’s “eye in the sky.”
Astronomers will use the Guizhou telescope to map the shape and formation of the universe, relying on its large size and a mobile detector suspended above the dish to explore space more quickly, deeply and thoroughly than they can with smaller telescopes. The telescope cost $184 million, recent Chinese state news reports said, although that figure seems unduly modest, given the telescope’s size. To ensure the project remains undisturbed, the government is moving more than 9,000 people.
Chinese science is often seen as serving the country’s economic and military expansion, seeking ruthlessly practical dividends.
But the telescope shows that the government in Beijing is also willing to spend heavily to propel China into the big leagues in research that offers few direct payoffs, apart from knowledge and prestige.
“Astronomy is an ultimate expression of ‘pure’ science that has little immediate practical benefits,” Luis C. Ho, the director of the Kavli Institute for Astronomy and Astrophysics at Peking University, said by email. “It is a luxury that only the most advanced economies enjoy.”
China’s history of subjugation to the West in previous centuries reinforced the belief that scientific prowess is essential for any modern power. And studying the heavens was, after all, an area where China excelled in ancient times.
[source: The New York Times, ]

Science and Information / Visions of Life on Mars in Earth’s Depths
« on: October 04, 2016, 07:11:57 PM »
A mile down in an unused mine tunnel, scientists guided by helmet lamps trudged through darkness and the muck of a flooded, uneven floor.
In the subterranean world of the Beatrix gold mine, they shed their backpacks, taking out tools and meticulously prepared test tubes to collect samples.
Leaning a ladder against the hard rock wall, Tullis C. Onstott, a geosciences professor at Princeton, climbed to open an old valve about a dozen feet up.
Out flowed water chock-full of microbes, organisms flourishing not from the warmth of the sun, but by heat generated from the interior of the planet below.
These tiny life-forms — bacteria and other microbes and even little worms — exist in places nearly impossible to reach, living in eternal darkness, in hard rock.
Scientists like Dr. Onstott have been on the hunt for life in the underworld, not just in South Africa but in mines in South Dakota and at the bottom of oceans.
What they learn could provide insights into where life could exist elsewhere in the solar system, including Mars.
Microbial Martians might well look like what lives in the rocks here at a deep underground mine.
The same conditions almost certainly exist on Mars. Drill a hole there, drop these organisms in, and they might happily multiply, fueled by chemical reactions in the rocks and drips of water.
“As long as you can get below the ice, no problems,” Dr. Onstott said. “They just need a little bit of water.”
Mars has long been a focus of space exploration and science fiction dreams. NASA has sent more robotic probes there than any other planet. But now there is renewed interest in sending people as well. NASA has been enthusiastically promoting its “Journey to Mars” goal to send astronauts there in the 2030s. Elon Musk, the billionaire founder of SpaceX, is promising that he will be able to get there a decade sooner and set up colonies.
Astronauts on Mars would be able to greatly accelerate the quest for answers to the most intriguing questions about the red planet. Was there ever life on Mars? Could there be life there today?
It was not that long ago that scientists had written off Mars as lifeless.
Forty years ago, NASA spent nearly $1 billion on its Viking mission, which revealed a cold, dry world seemingly devoid of organic molecules that are the building blocks of life.
But more recent missions have discovered compelling evidence that Mars was not always such an uninviting place. In its youth, more than three billion years ago, the planet was warmer and wetter, blanketed with a thick atmosphere — possibly almost Earthlike.
A fanciful but plausible notion is that life did originate on Mars, then traveled to Earth via meteorites, and we are all descendants of Martians.
Eventually, Mars did turn cold and dry. Radiation broke apart the water molecules, and the lighter hydrogen atoms escaped to space. The atmosphere thinned to wisps.
But if life did arise on Mars, might it have migrated to the underworld and persisted?
For a couple of decades, Dr. Onstott has been talking his way into South African gold mines, regaling the mine managers with the wonder of deep Earth life to overcome their wariness. In many ways, the mines provide easy access to the depths — a ride in a cagelike elevator, jammed against miners starting their shift, descending quickly as lights from the different levels zip past. Think of it as traveling through a 450-story skyscraper, going down.
Dr. Onstott and his colleagues had made repeated pilgrimages to this particular tunnel in this particular mine, Beatrix, 160 miles southwest of Johannesburg.
When miners carve out new tunnels, they poke holes through the rock to see what surprises might lie ahead. Sometimes the borehole taps into a section of fractured rock with water coursing through. Then the fracture is drained and plugged.
But this particular tunnel at Beatrix never entered production, so the borehole valve remains, allowing the scientists to return to draw samples from the same place.
Continue reading the main story
At this level, almost a mile underground, the elevator gates open to a well-lit, concrete cavern with the unremarkable plainness of a parking garage. A minirailway system transports miners and ore back and forth. The side tunnel, though, is pitch black save for the helmet lamps, and the trek to the valve is a slosh through muck and over tangles of mangled electrical cabling.
Scientists led by Dr. Onstott made their most recent trip to South Africa in June last year. Over a couple of hours, they took their fill of the water and set up an apparatus that remains attached to the valve, trapping microbes, which were retrieved later in the summer. Since then, they have been analyzing the samples to understand this assemblage of life.
[Source: The New York Times]

"Basic Concepts in Physics: From the Cosmos to Quarks" is the outcome of the authors' long and varied teaching experience in different countries and for different audiences, and gives an accessible and eminently readable introduction to all the main ideas of modern physics. The book’s fresh approach, using a novel combination of historical and conceptual viewpoints, makes it ideal complementary reading to more standard textbooks. The first five chapters are devoted to classical physics, from planetary motion to special relativity, always keeping in mind its relevance to questions of contemporary interest. The next six chapters deal mainly with newer developments in physics, from quantum theory and general relativity to grand unified theories, and the book concludes by discussing the role of physics in living systems. A basic grounding in mathematics is required of the reader, but technicalities are avoided as far as possible; thus complex calculations are omitted so long as the essential ideas remain clear. The book is addressed to undergraduate and graduate students in physics and will also be appreciated by many professional physicists. It will likewise be of interest to students, researchers and teachers of other natural sciences, as well as to engineers, high-school teachers and the curious general reader, who will come to understand what physics is about and how it describes the different phenomena of Nature. Not only will readers of this book learn much about physics, they will also learn to love it.

Books / Concepts of Modern Physics by Arthur Beiser
« on: July 02, 2015, 01:18:49 PM »

Modern Physics is the most up-to-date. The book is intended to be used in a one-semester course covering modern physics for students who have already had basic physics and calculus courses. The balance of the book leans more toward ideas than toward experimental methods and practical applications because the beginning student is better served by a conceptual framework than by a mass of details. The sequence of topics follows a logical, rather than strictly historical, order. Relativity and quantum ideas are considered first to provide a framework for understanding the physics of atoms and nuclei. The theory of the atom is then developed, and followed by a discussion of the properties of aggregates of atoms, which includes a look at statistical mechanics. Finally atomic nuclei and elementary particles are examined.

Pages: [1]