Physics posts
- September 7, 2010
- 11:47 PM
- 620 views
The World of Tractography Where The White Matter Tracts Appear Colored
by Amiya Kumar Sarkar in Physiology physics woven fine
White matter tractography, a relatively new MRI based technique, can delineate fiber tracts and assist in surgical planning and research.... Read more »
P. Mukherjee,, J.I. Berman,, S.W. Chung,, C.P. Hess, & R.G. Henry. (2008) Diffusion Tensor MR Imaging and Fiber Tractography: Theoretic Underpinnings. AM J Neuroradiol . DOI: 10.3174/ajnr.A1051
- September 7, 2010
- 01:13 PM
- 1,018 views
Standard Cosmology Theory Is Confirmed By ACT For Smallest Scales In The Universe.
by Joseph Smidt in The Eternal Universe
It never ceases to amaze me how well standard cosmology theory fits the ever increasing amount of data with precision. The results just released from the Atacama Cosmology Telescope (ACT) confirm that, even on the smallest scales, the predictions of the Lambda CDM universe preceded by an epic of inflation are correct. This study extracts data for L modes of The CMB between 500 and 10,000. (For
... Read more »
Sudeep Das, Tobias A. Marriage, & et al. (2010) The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey. E-Print. arXiv: 1009.0847v1
- September 3, 2010
- 08:19 PM
- 1,375 views
In other news: shrinking computer chips, string theory
by Joerg Heber in All That Matters
This week two noteworthy papers have been published that I did not get around to highlight here. In terms of topic they could not be more different, one about a possible new data storage material, and the other one about string theory! The next big thing in computing could be silicon! It is not often [...]... Read more »
Yao, J., Sun, Z., Zhong, L., Natelson, D., & Tour, J. M. (2010) Resistive Switches and Memories from Silicon Oxide. Nano Letters. DOI: 10.1021/nl102255r
L. Borsten, D. Dahanayake, M. J. Duff, A. Marrani, & W. Rubens. (2010) Four-qubit entanglement from string theory. Phys.Rev.Lett.105:100507,2010. arXiv: 1005.4915v2
- September 2, 2010
- 04:33 PM
- 616 views
Free Kick Physics, Roberto Carlos Style
by Michael Gutbrod in A Scientific Nature
For all you soccer/football/fútbol/calcio fans out there, you may have been watching the 1997 Confederations Cup match between Brazil and France when Roberto Carlos lined up for a 35 meter (115 ft.), relatively long, free kick. Then you either screamed in unbridled joy or a crying disgust as Carlos appeared to botch the free kick [...]... Read more »
Guillaume Dupeux, Anne Le Goff, David Quéré and Christophe Clanet. (2010) The spinning ball spiral. New Journal of Physics. info:/
- September 2, 2010
- 06:04 AM
- 1,229 views
Solar system might be older than we thought…
by Kelly Oakes in Basic Space
Researchers from Arizona State University have found the oldest solar system object ever discovered. In fact, it’s so old that it formed up to two million years before the solar system did, according to current estimates. It might be time for a rethink of when and how our little place in the Universe came into [...]... Read more »
Audrey Bouvier, & Meenakshi Wadhwa. (2010) The age of the Solar System redefined by the oldest Pb–Pb age of a meteoritic inclusion. Nature Geoscience. info:/10.1038/ngeo941
- September 1, 2010
- 01:20 PM
- 1,414 views
This (Long) Week in the Universe: August 24th – September 1st
by S.C. Kavassalis in The Language of Bad Physics
What have people been talking about this week in high energy physics, astrophysics, gravitation, general relativity and quantum gravity?... Read more »
Lisa J. Kewley, David Rupke, H. Jabran Zahid, Margaret J. Geller, & Elizabeth J. Barton. (2010) Metallicity Gradients and Gas Flows in Galaxy Pairs. arXiv. DOI: 1008.2204
Mayer L, Kazantzidis S, Escala A, & Callegari S. (2010) Direct formation of supermassive black holes via multi-scale gas inflows in galaxy mergers. Nature, 466(7310), 1082-4. PMID: 20740009
Mikhail Gorchtein, Stefano Profumo, & Lorenzo Ubaldi. (2010) Probing Dark Matter with AGN Jets. arXiv. arXiv: 1008.2230v1
J. K. Webb, J. A. King, M. T. Murphy, V. V. Flambaum, R. F. Carswell, & M. B. Bainbridge. (2010) Evidence for spatial variation of the fine structure constant. arXiv. arXiv: 1008.3907v1
Harold V. Parks, & James E. Faller. (2010) A Simple Pendulum Determination of the Gravitational Constant. Phys. Rev. Let. arXiv: 1008.3203v2
L. Borsten, D. Dahanayake, M. J. Duff, A. Marrani, & W. Rubens. (2010) Four-qubit entanglement from string theory. Physical Review Letters. arXiv: 1005.4915v2
- September 1, 2010
- 01:03 PM
- 1,473 views
The thing with graphene transistors
by Joerg Heber in All That Matters
Graphene is one of the hottest research areas in nanotechnology, and it may seem slightly surprising it took me a month to write my first blog post on the topic. That moment has now come, with the advance publication of a Nature paper that presents highly attractive graphene transistor, even though in my humble opinion [...]... Read more »
Liao, L., Lin, Y.-C., Bao, M., Cheng, R., Bai, J., Liu, Y., Qu, Y., Wang, K. L., Huang, Y., & Duan, X. (2010) High-speed graphene transistors with a self-aligned nanowire gate. Nature. DOI: 10.1038/nature09405
- September 1, 2010
- 01:00 PM
- 1,207 views
The "Bad" Language of Physics
by S.C. Kavassalis in The Language of Bad Physics
One of the things I sometimes find myself writing about is the “bad” language used by physicists. Sometimes we say Riemannian when we really should say psuedo-Riemannian, sometimes we call something a metric when it really is a line element – the kind of nitpicky pet-peeves that practically everyone has about literature in their field. Today, I’m going to be talking about the bad language in physics in a totally different context however.... Read more »
Regge, T. (1961) General relativity without coordinates. Il Nuovo Cimento, 19(3), 558-571. DOI: 10.1007/BF02733251
Galassi, M. (1993) Lapse and shift in Regge calculus. Physical Review D, 47(8), 3254-3264. DOI: 10.1103/PhysRevD.47.3254
Kheyfets A, LaFave NJ, & Miller WA. (1990) Null-strut calculus. II. Dynamics. Physical review D: Particles and fields, 41(12), 3637-3651. PMID: 10012308
ALPER ÜNGÖR, & ALLA SHEFFER. (2002) PITCHING TENTS IN SPACE-TIME: MESH GENERATION FOR DISCONTINUOUS GALERKIN METHOD. International Journal of Foundations of Computer Science , 13(2). info:/10.1142/S0129054102001059
- August 31, 2010
- 09:00 PM
- 1,012 views
The Bad Language of Physics
by S.C. Kavassalis in The Language of Bad Physics
One of the things I sometimes find myself writing about is the “bad” language used by physicists. Sometimes we say Riemannian when we really should say psuedo-Riemannian, sometimes we call something a metric when it really is a line element – the kind of nitpicky pet-peeves that practically everyone has about literature in their field. Today, I’m going to be talking about the bad language in physics in a totally different context however.
Teepee Lattices, Future-Pointing Wigwams ........ Read more »
Regge, T. (1961) General relativity without coordinates. Il Nuovo Cimento, 19(3), 558-571. DOI: 10.1007/BF02733251
Galassi, M. (1993) Lapse and shift in Regge calculus. Physical Review D, 47(8), 3254-3264. DOI: 10.1103/PhysRevD.47.3254
Kheyfets A, LaFave NJ, & Miller WA. (1990) Null-strut calculus. II. Dynamics. Physical review D: Particles and fields, 41(12), 3637-3651. PMID: 10012308
ALPER ÜNGÖR, & ALLA SHEFFER. (2002) PITCHING TENTS IN SPACE-TIME: MESH GENERATION FOR DISCONTINUOUS GALERKIN METHOD. International Journal of Foundations of Computer Science , 13(2). info:/10.1142/S0129054102001059
- August 31, 2010
- 01:51 PM
- 876 views
Seeing double: perhaps is simply optical diplopia
by Pablo Artal in Optics confidential
Changes in the optics of the eye can produce double or even multiple images... a real case is explained as an example and more... ... Read more »
Pérez, G., Abenza, S., De Casas, A., Marín, J., & Artal, P. (2010) Cause of Monocular Diplopia Diagnosed by Combining Double-pass Retinal Image Assessment and Hartmann-Shack Aberrometry. Journal of Refractive Surgery, 26(4), 301-304. DOI: 10.3928/1081597X-20100218-05
- August 31, 2010
- 07:21 AM
- 637 views
Solar cells brought into shape
by Joerg Heber in All That Matters
Solar energy is a huge market and any improvement to the efficiency of solar cells has a significant impact. In 2008, worldwide photovoltaic solar energy production was about 5 gigawatts, and this is expected to rise to 15 gigawatts in 2015. To put this figure in context, a nuclear reactor produces around 1 to 1.5 [...]... Read more »
Ferry, V., Verschuuren, M., Li, H., Verhagen, E., Walters, R., Schropp, R., Atwater, H., & Polman, A. (2010) Light trapping in ultrathin plasmonic solar cells. Optics Express, 18(S2). DOI: 10.1364/OE.18.00A237
Atwater, H., & Polman, A. (2010) Plasmonics for improved photovoltaic devices. Nature Materials, 9(3), 205-213. DOI: 10.1038/nmat2629
- August 30, 2010
- 03:44 PM
- 993 views
Hacking Commercial Quantum Cryptography Systems by Illumination
by Olexandr Isayev in olexandrisayev.com
Quantum hackers have performed the first 'invisible' attack on two commercial quantum cryptographic systems. By using lasers on the systems — which use quantum states of light to encrypt information for transmission — they have fully cracked their encryption keys, yet left no trace of the hack.... Read more »
Lydersen, L., Wiechers, C., Wittmann, C., Elser, D., Skaar, J., & Makarov, V. (2010) Hacking commercial quantum cryptography systems by tailored bright illumination. Nature Photonics. DOI: 10.1038/NPHOTON.2010.214
Feihu Xu, Bing Qi, & Hoi-Kwong Lo. (2010) Experimental demonstration of phase-remapping attack in a practical quantum key distribution system. Preprint. arXiv: 1005.2376v1
- August 30, 2010
- 12:49 PM
- 1,379 views
Indirect Excitation Control: Ultrafast Quantum Gates for Single Atomic Qubits
by Chad Orzel in Uncertain Principles
Last week, John Baez posted a report on a seminar by Dzimitry Matsukevich on ion trap quantum information issues. In the middle of this, he writes:
Once our molecular ions are cold, how can we get them into specific desired states? Use a mode locked pulsed laser to drive stimulated Raman transitions.
Huh? As far as I can tell, this means "blast our molecular ion with an extremely brief pulse of light: it can then absorb a photon and emit a photon of a different energy, while itself jumping to ........ Read more »
Campbell, W., Mizrahi, J., Quraishi, Q., Senko, C., Hayes, D., Hucul, D., Matsukevich, D., Maunz, P., & Monroe, C. (2010) Ultrafast Gates for Single Atomic Qubits. Physical Review Letters, 105(9). DOI: 10.1103/PhysRevLett.105.090502
- August 29, 2010
- 04:45 PM
- 694 views
A Mathematical Description of Cell Aggregate Mechanical Deformation
by Michael Long in Phased
Luigi Preziosi (Politecnico di Torino, Italy) and coworkers have developed a mathematical model for the mechanical stress experienced by cell aggregates, relevant to cellular function in normal health (blood flow) and disease (cancer). This news feature was written on August 29, 2010.... Read more »
Preziosi, L., Ambrosi, D., & Verdier, C. (2010) An elasto-visco-plastic model of cell aggregates. Journal of Theoretical Biology, 262(1), 35-47. DOI: 10.1016/j.jtbi.2009.08.023
- August 29, 2010
- 10:36 AM
- 1,899 views
the birth of a supermassive monster, revisited
by Greg Fish in weird things
We know that black holes can grow to become absolutely enormous in size, tipping the scales at billions and billions of times the mass of our sun. The numbers involved make the gravitational monsters in question very hard to visualize, and pose a big mystery. Did they form from the remnants of the first stars [...]... Read more »
Mayer, L., Kazantzidis, S., Escala, A., & Callegari, S. (2010) Direct formation of supermassive black holes via multi-scale gas inflows in galaxy mergers. Nature, 466(7310), 1082-1084. DOI: 10.1038/nature09294
- August 27, 2010
- 07:34 AM
- 1,218 views
Snapshots of magnetic fields
by Joerg Heber in All That Matters
In the absence of GPS, a compass is the best option to find your way around. However, although the earth’s magnetic field is a great way to find your own position, doing the reverse, measuring magnetic fields with a high accuracy — on an atomic scale — remains a challenge. Sure, there are electron microscopes, which are [...]... Read more »
Park, H., Baskin, J., & Zewail, A. (2010) 4D Lorentz Electron Microscopy Imaging: Magnetic Domain Wall Nucleation, Reversal, and Wave Velocity. Nano Letters, 2147483647. DOI: 10.1021/nl102861e
- August 26, 2010
- 12:42 PM
- 1,533 views
Measuring Gravity: Ain't Nothin' but a G Thing
by Chad Orzel in Uncertain Principles
There's a minor scandal in fundamental physics that doesn't get talked about much, and it has to do with the very first fundamental force discovered, gravity. The scandal is the value of Newton's gravitational constant G, which is the least well known of the fundamental constants, with a value of 6.674 28(67) x 10-11 m3 kg-1 s-2. That may seem pretty precise, but the uncertainty (the two digits in parentheses) is scandalously large when compared to something like Planck's constant at 6.626 068 9........ Read more »
Gundlach, J., & Merkowitz, S. (2000) Measurement of Newton's Constant Using a Torsion Balance with Angular Acceleration Feedback. Physical Review Letters, 85(14), 2869-2872. DOI: 10.1103/PhysRevLett.85.2869
Schlamminger, S., Holzschuh, E., Kündig, W., Nolting, F., Pixley, R., Schurr, J., & Straumann, U. (2006) Measurement of Newton’s gravitational constant. Physical Review D, 74(8). DOI: 10.1103/PhysRevD.74.082001
Luo, J., Liu, Q., Tu, L., Shao, C., Liu, L., Yang, S., Li, Q., & Zhang, Y. (2009) Determination of the Newtonian Gravitational Constant G with Time-of-Swing Method. Physical Review Letters, 102(24). DOI: 10.1103/PhysRevLett.102.240801
Harold V. Parks, & James E. Faller. (2010) A Simple Pendulum Determination of the Gravitational Constant. Physical Review Letters (accepted). arXiv: 1008.3203v2
- August 25, 2010
- 11:50 PM
- 1,033 views
Solid-state lighting: may not be magic bullet for energy savings
by Olexandr Isayev in olexandrisayev.com
The importance of artificial light to society has long been recognized with the utilization of fire thought of as the quintessential human invention. Now scientists have found that emerging, more energy efficient lighting technologies could be the key to a better quality of life. New research published on August 19 , in a special issue [...]... Read more »
Tsao, J., Saunders, H., Creighton, J., Coltrin, M., & Simmons, J. (2010) Solid-state lighting: an energy-economics perspective. Journal of Physics D: Applied Physics, 43(35), 354001. DOI: 10.1088/0022-3727/43/35/354001
- August 25, 2010
- 09:38 AM
- 1,434 views
Melting Simulated Insulators
by Chad Orzel in Uncertain Principles
The Joerg Heber post that provided one of the two papers for yesterday's Hanbury Brown Twiss-travaganza also included a write-up of a new paper in Nature on Mott insulators, which was also written up in Physics World.
Most of the experimental details are quite similar to a paper by Markus Greiner's group I wrote up in June: They make a Bose-Einstein Condensate, load it into an optical lattice, and use a fancy lens system to detect individual atoms at sites of the lattice. This lattice can be pr........ Read more »
Sherson, J., Weitenberg, C., Endres, M., Cheneau, M., Bloch, I., & Kuhr, S. (2010) Single-atom-resolved fluorescence imaging of an atomic Mott insulator. Nature. DOI: 10.1038/nature09378
- August 25, 2010
- 06:25 AM
- 1,310 views
More Hanbury Brown and Twiss fun
by Joerg Heber in All That Matters
Last week I wrote about interesting physics that can be done with ultracold atoms. One of the experiments I described was related to the Hanbury Brown-Twiss effect. Although I mentioned the experiment in some detail, the focus of my post was more on the analogies between ultracold atom systems and other physical systems. I did [...]... Read more »
BROWN, R., & TWISS, R. (1956) Correlation between Photons in two Coherent Beams of Light. Nature, 177(4497), 27-29. DOI: 10.1038/177027a0
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