SpaceX Falcon 9 Reusable Launch Vehicle Launches and then Reenters and Lands Perfectly on the Surface of the Ocean

by Tommy on 19/04/2014
SpaceX Falcon 9 Reusable CRS 3 Launch Vehicle Water Bath

SpaceX Falcon 9 Reusable CRS 3 Launch Vehicle Water Bath

U Ra.

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Tin Selenide SnSe is an Extraordinary High Temperature Thermoelectric Material

by Tommy on 19/04/2014

http://www.nature.com/nature/journal/v508/n7496/full/nature13184.html

Ultralow thermal conductivity and high thermoelectric figure of merit in SnSe crystals, Li-Dong Zhao, Shih-Han Lo, Yongsheng Zhang, Hui Sun, Gangjian Tan, Ctirad Uher, C. Wolverton, Vinayak P. Dravid and Mercouri G. Kanatzidis. Nature, 508, 373–377, 17 April 2013

The thermoelectric effect enables direct and reversible conversion between thermal and electrical energy, and provides a viable route for power generation from waste heat. The efficiency of thermoelectric materials is dictated by the dimensionless figure of merit, ZT (where Z is the figure of merit and T is absolute temperature), which governs the Carnot efficiency for heat conversion. Enhancements above the generally high threshold value of 2.5 have important implications for commercial deployment, especially for compounds free of Pb and Te. Here we report an unprecedented ZT of 2.6 ± 0.3 at 923 K, realized in SnSe single crystals measured along the b axis of the room-temperature orthorhombic unit cell. This material also shows a high ZT of 2.3 ± 0.3 along the c axis but a significantly reduced ZT of 0.8 ± 0.2 along the a axis. We attribute the remarkably high ZT along the b axis to the intrinsically ultralow lattice thermal conductivity in SnSe. The layered structure of SnSe derives from a distorted rock-salt structure, and features anomalously high Grüneisen parameters, which reflect the anharmonic and anisotropic bonding. We attribute the exceptionally low lattice thermal conductivity (0.23 ± 0.03 W m−1 K<sup−1</sup> at 973 K) in SnSe to the anharmonicity. These findings highlight alternative strategies to nanostructuring for achieving high thermoelectric performance.

Ok. There you have it! Who could have known, lol.

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Mexican Mammoth Site Reveals Volcanic and Meteorite Layers

by Tommy on 17/04/2014

http://www.sciencedirect.com/science/article/pii/S1040618214001529

Paleoindian sites from the Basin of Mexico: Evidence from stratigraphy, tephrochronology and dating, Silvia Gonzalez, David Huddart, Isabel Israde -Alcántara, Gabriela Domínguez-Vázquez, James Bischoff and Nicholas Felstead, Quaternary International, 29 March 2014

We present new data on the stratigraphy, dating and tephrochonology at the most important Paleoindian sites in the Basin of Mexico. These include: a) Peñon Woman III, with the oldest directly radiocarbon dated human remains (10,755 ± 75 BP); b) Tlapacoya, with two human crania dated to just over 10 ka BP; c) Tocuila, an important mammoth site with incorporation of fossils and suggested bone tools within the Upper Toluca Pumice (UTP) lahar (volcanic mudflow). The Tocuila site also includes potential evidence for a layer associated with the Younger Dryas meteorite airburst, with charcoal, iron microspherules, micro-tektites (melted glass) and volcanic ash, dated to 10,800 ± 50 BP and d) the Santa Isabel Iztapan mammoths I and II with lithics of Scottsbluff, Lerma and Angostura types and obsidian prismatic blades but lacking the characteristic fluted Clovis type points normally associated with mammoth kills and butchering and dated after the Pumice with Andesite (PWA) layer between 14,500 BP and 10,900 BP, before the Younger Dryas interval. These results show that these lithic traditions in Central Mexico are older than in the Great Plains of USA. Several tephra markers are recognised in the sites that help to constrain the stratigraphy and dating of the archaeological sequences. However tephra reworking in marginal lake sites is present and has been carefully considered, especially for the PWA tephra.

Liverpool John Moores University Press Release

I want a second opinion. We want samples.

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Catastrophic Sub Glacial Ice Lake Discharge Floods Created Chaotic Terrains on Mars

by Tommy on 17/04/2014

http://arxiv.org/abs/1404.3858

Catastrophic ice lake collapse in Aram Chaos, Mars, Manuel Roda, Maarten G. Kleinhans, Tanja E. Zegers and Jelmer H.P. Oosthoek, Icarus, 23 March 2014

Hesperian chaotic terrains have been recognized as the source of outflow channels formed by catastrophic outflows. Four main scenarios have been proposed for the formation of chaotic terrains that involve different amounts of water and single or multiple outflow events. Here, we test these scenarios with morphological and structural analyses of imagery and elevation data for Aram Chaos in conjunction with numerical modeling of the morphological evolution of the catastrophic carving of the outflow valley. The morphological and geological analyses of Aram Chaos suggest large-scale collapse and subsidence (1500 m) of the entire area, which is consistent with a massive expulsion of liquid water from the subsurface in one single event. The combined observations suggest a complex process starting with the outflow of water from two small channels, followed by continuous groundwater sapping and headward erosion and ending with a catastrophic lake rim collapse and carving of the Aram Valley, which is synchronous with the 2.5 Ga stage of the Ares Vallis formation. The water volume and formative time scale required to carve the Aram channels indicate that a single, rapid (maximum tens of days) and catastrophic (flood volume of 9.3 × 104 km3) event carved the outflow channel. We conclude that a sub-ice lake collapse model can best explain the features of the Aram Chaos Valley system as well as the time scale required for its formation.

I’m glad I wasn’t around for that one!

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Asteroid Redirect Mission – Broad Agency Announcement

by Tommy on 13/04/2014

https://prod.nais.nasa.gov/cgibin/eps/sol.cgi?acqid=159813

NNH14ZCQ002K – Appendix E

Partnership opportunities for the Asteroid Redirect Crewed Mission or future missions in areas such as advancing science and in-situ resource utilization, enabling commercial activities, and enhancing U.S. exploration activities in cis-lunar space after the first crewed mission to an asteroid.

Full proposal due May 5th. Fifty grand for six months work.

I’ve already got it mostly worked out.

Asteroid Redirect Mission

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Domain Walls Implicated in Unconventional Superconductivity

by Tommy on 10/04/2014

http://www.nature.com/nphys/journal/vaop/ncurrent/abs/nphys2935.html

Emergence of charge density wave domain walls above the superconducting dome in 1T-TiSe2, Y. I. Joe, X. M. Chen, P. Ghaemi, K. D. Finkelstein, G. A. de la Peña, Y. Gan, J. C. T. Lee, S. Yuan, J. Geck, G. J. MacDougall, T. C. Chiang, S. L. Cooper, E. Fradkin and P. Abbamonte, Nature Physics, 6 April 2014

Superconductivity in so-called unconventional superconductors is nearly always found in the vicinity of another ordered state, such as antiferromagnetism, charge density wave (CDW), or stripe order. This suggests a fundamental connection between superconductivity and fluctuations in some other order parameter. To better understand this connection, we used high-pressure X-ray scattering to directly study the CDW order in the layered dichalcogenide TiSe2, which was previously shown to exhibit superconductivity when the CDW is suppressed by pressure or intercalation of Cu atoms. We succeeded in suppressing the CDW fully to zero temperature, establishing for the first time the existence of a quantum critical point (QCP) at Pc = 5.1 ± 0.2 GPa, which is more than 1 GPa beyond the end of the superconducting region. Unexpectedly, at P = 3 GPa we observed a reentrant, weakly first order, incommensurate phase, indicating the presence of a Lifshitz tricritical point somewhere above the superconducting dome. Our study suggests that superconductivity in TiSe2 may not be connected to the QCP itself, but to the formation of CDW domain walls.

OMG … who knew!

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3D Topological Semimetal Cadmium Arsenide Cd3As2 Verified

by Tommy on 9/04/2014

http://arxiv.org/abs/1404.2557

Quantum transport in the three-dimensional Dirac semimetal Cd3As2, L. P. He, X. C. Hong, J. K. Dong, J. Pan, Z. Zhang, J. Zhang and S. Y. Li

The material termed three-dimensional (3D) Dirac semimetal has attracted great interests recently, since it is an electronic analogue to two-dimensional graphene. Soon after the theoretical predictions of BiO2, A3Bi (A = Na, K, Rb), and Cd3As2 as candidates of 3D Dirac semimetal, the angle-resolve photoemission spectroscopy experiments indeed observed 3D Dirac points in Na3Bi and Cd3As2. The scanning tunnelling microscopy measurements also support Dirac-like dispersion in Cd3As2. Here we report quantum transport properties of Cd3As2 single crystal in magnetic field. A sizable linear quantum magnetoresistance is found near room temperature, which indicates the existence of linear gapless energy dispersion. Below 100 K, strong Shubnikov-de Haas oscillations appear in the longitudinal resistivity with a single frequency F = 58.3 T. The linear dependence of Landau index n on 1/B gives an n-axis intercept 0.58, which reveals the nontrivial Berry’s phase expected for 3D Dirac fermions. These quantum transport results provide strong bulk evidences for a 3D Dirac semimetal phase in Cd3As2.

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BCS – BEC Crossover and the Unitary Fermi Gas Reviewed

by Tommy on 8/04/2014

http://arxiv.org/abs/1306.5785

BCS-BEC Crossover and the Unitary Fermi Gas, Mohit Randeria and Edward Taylor, Invited article for Annual Reviews of Condensed Matter Physics, Published Version

The crossover from weak coupling Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) of tightly bound pairs, as a function of the attractive interaction in Fermi systems, has long been of interest to theoretical physicists. The past decade has seen a series of remarkable experimental developments in ultracold Fermi gases that has realized the BCS-BEC crossover in the laboratory, bringing with it fresh new insights into the very strongly interacting unitary regime in the middle of this crossover. In this review, we start with a pedagogical introduction to the crossover and then focus on recent progress in the strongly interacting regime. While our focus is on new theoretical developments, we also describe three key experiments that probe the thermodynamics, transport and spectroscopy of the unitary Fermi gas. We discuss connections between the unitary regime and other areas of physics — quark-gluon plasmas, gauge-gravity duality and high temperature superconductivity — and conclude with open questions about strongly interacting Fermi gases.

This extensive review has been out for a while, by the guy who wrote the book.

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New Single Crystal Monolayer Graphene Synthesis Described

by Tommy on 5/04/2014

http://www.sciencemag.org/content/early/2014/04/02/science.1252268

Wafer-Scale Growth of Single-Crystal Monolayer Graphene on Reusable Hydrogen-Terminated Germanium, Jae-Hyun Lee, Eun Kyung Lee, Won-Jae Joo, Yamujin Jang, Byung-Sung Kim, Jae Young Lim, Soon-Hyung Choi, Sung Joon Ahn, Joung Real Ahn, Min-Ho Park, Cheol-Woong Yang, Byoung Lyong Choi, Sung-Woo Hwang, Dongmok Whang, Science, 3 April 2014

The uniform growth of single-crystal graphene over wafer-scale areas remains a challenge in the commercial-level manufacturability of various electronic, photonic, mechanical, and other devices based on graphene. Here, we describe wafer-scale growth of wrinkle-free single-crystal monolayer graphene on silicon wafer using a hydrogen-terminated germanium buffer layer. The anisotropic twofold symmetry of the germanium (110) surface allowed unidirectional alignment of multiple seeds, which were merged to uniform single-crystal graphene with predefined orientation. Furthermore, the weak interaction between graphene and underlying hydrogen-terminated germanium surface enabled the facile etch-free dry transfer of graphene and the recycling of the germanium substrate for continual graphene growth.

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The Archimedes Project – Life Support on a Space Station

by Tommy on 28/03/2014
Archimedes Sphere

Archimedes Sphere

http://webpages.charter.net/archimedes/Thomas_Lee_Elifritz.pdf

http://webpages.charter.net/tsiolkovsky/Space_Station.pdf

http://webpages.charter.net/archimedes/

Ok, that was stupid.

Next

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Ultra Bipolaronic Super High Dielectric Materials Proposed

by Tommy on 27/03/2014

http://arxiv.org/abs/1403.6862

Super Dielectric Materials, Sam Fromille and Jonathan Phillips

Evidence is provided that a class of materials with dielectric constants greater than 105, herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants greater than 4*108 in all cases, a remarkable increase over the best dielectric constants previously measured, ca. 1*104. It is postulated that any porous, electrically insulating material (e.g. high surface area powders of silica, titania), filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution), herein called New Paradigm Super (NPS) capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relative high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å) of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 volts, water begins to break down, creating enough ionic species to ‘short’ the individual water droplets. Potentially NPS capacitor stacks can surpass ‘supercapacitors’ in volumetric energy density.

Super weird. I feel a song coming on!

Update : dielectric catastrophe.

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Long Lived Higgs Mode in a Trapped Fermi Gas Proposed

by Tommy on 27/03/2014

http://arxiv.org/abs/1403.6876

A long-lived Higgs mode in a two-dimensional confined Fermi gas, Georg M. Bruun

The Higgs mode corresponds to the collective motion of particles due to the vibrations of an invisible field. It plays a fundamental role for our understanding of both low and high energy physics, giving elementary particles their mass and leading to collective modes in condensed matter and nuclear systems. The Higgs mode has been observed in a limited number of table-top systems, where it however is characterized by a short lifetime due to decay into a continuum of modes. A major goal which has remained elusive so far, is therefore to realize a long-lived Higgs mode in a controllable system. Here, we show how an undamped Higgs mode can be observed unambiguously in a Fermi gas in a two-dimensional trap, close to a quantum phase transition between a normal and a superfluid phase. We develop a first-principles theory of the pairing and the associated collective modes, which is quantitatively reliable when the pairing energy is much smaller than the trap level spacing, yet simple enough to allow the derivation of analytical results. The theory includes the trapping potential exactly, which is demonstrated to stabilize the Higgs mode by making its decay channels discrete. Our results show how atoms in micro-traps can unravel properties of a long-lived Higgs mode, including the role of confinement and finite size effects.

Super duper awesomely cool.

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Leo Kadanoff Publishes His Opus On Quantum Entropy

by Tommy on 25/03/2014

http://arxiv.org/abs/1403.6162

Entropy in in Flux, Leo P. Kadanoff

The science of thermodynamics was put together in the Nineteenth Century to describe large systems in equilibrium. One part of thermodynamics defines entropy for equilibrium systems and demands an ever-increasing entropy for non-equilibrium ones. However, starting with the work of Ludwig Boltzmann in 1872, and continuing to the present day, various models of non-equilibrium behavior have been put together with the specific aim of generalizing the concept of entropy to non-equilibrium situations. This kind of entropy has been termed {\em kinetic entropy} to distinguish it from the thermodynamic variety. Knowledge of kinetic entropy started from Boltzmann’s insight about his equation for the time dependence of gaseous systems. In this paper, his result is stated as a definition of kinetic entropy in terms of a local equation for the entropy density. This definition is then applied to Landau’s theory of the Fermi liquid thereby giving the kinetic entropy within that theory.

Entropy has been defined and used for a wide variety of situations in which a condensed matter system has been allowed to relax for a sufficient period so that the very most rapid fluctuations have been ironed out. One of the broadest applications of non-equilibrium analysis considers quantum degenerate systems using Martin-Schwinger Green’s functions\cite{MS} as generalized of Wigner functions, g< and g>. This paper describes once again these how the quantum kinetic equations for these functions give locally defined conservation laws for mass momentum and energy. In local thermodynamic equilibrium, this kinetic theory enables a reasonable local definition of entropy density. However, when the system is outside of local equilibrium, this definition fails. It is speculated that quantum entanglement is the source of this failure.

See also : http://arxiv.org/abs/1403.6464

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High Energy Electron Boson Fluctuation Spectra Observed in the Cuprates

by Tommy on 24/03/2014

http://arxiv.org/abs/1403.5630

High energy fluctuation spectra in cuprates from infrared optical spectroscopy, Jungseek Hwang and J. P. Carbotte, Physical Review B 89, 024502 (2014)

Coupling of the charge carriers in the high temperature superconducting oxides to bosonic modes has been widely reported using a variety of experimental probes. These include angular resolved photoemission (ARPES), scanning tunnelling spectroscopy (STS), Raman scattering (RS) and infrared optical spectroscopy (IRS). The energy scale investigated has been mostly limited to a relatively small range up to 300 meV or so. Although some ARPES experiments report boson structure up to 800 meV in the dressed electron dispersion curves the data are not analyzed to recover the spectral density of the fluctuation spectrum. We have extended to higher energies up to 2.2 eV the usual maximum entropy technique used to invert optical data so as to obtain an electron-boson spectral density. This has required that we include in our inversions, the calculated (LDA) particle-hole symmetrized energy dependent electronic density of states (DOS). Our analysis reveals that significant spectral weight remains in the fluctuation spectra up to 2.2 eV in the Bi-2212 family and to 1.2 eV in Bi-2201 for all doping levels considered.

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Synthetic Tracking Detects Faint Fast Near Earth Asteroid

by Tommy on 23/03/2014

http://arxiv.org/abs/1403.4353

Detection of a faint fast-moving near-Earth asteroid using synthetic tracking technique, Chengxing Zhai, Michael Shao, Bijan Nemati, Thomas A. Werne, Hanying Zhou, Slava G. Turyshev, Jagmit Sandhu, Gregg W. Hallinan and Leon K. Harding

We report a detection of a faint near-Earth asteroid (NEA), which was done using our synthetic tracking technique and the CHIMERA instrument on the Palomar 200-inch telescope. This asteroid, with apparent magnitude of 23, was moving at 5.97 degrees per day and was detected at a signal-to-noise ratio (SNR) of 15 using 30 sec of data taken at a 16.7 Hz frame rate. The detection was confirmed by a second observation one hour later at the same SNR. The asteroid moved 7 arcseconds in sky over the 30 sec of integration time because of its high proper motion. The synthetic tracking using 16.7 Hz frames avoided the trailing loss suffered by conventional techniques relying on 30-sec exposure, which would degrade the surface brightness of image on CCD to an approximate magnitude of 25. This detection was a result of our 12-hour blind search conducted on the Palomar 200-inch telescope over two nights on September 11 and 12, 2013 scanning twice over six 5.0 deg x 0.043 deg fields. The fact that we detected only one NEA, is consistent with Harris’s estimation of the asteroid population distribution, which was used to predict the detection of 1–2 asteroids of absolute magnitude H=28–31 per night. The design of experiment, data analysis method, and algorithms for estimating astrometry are presented. We also demonstrate a milli-arcsecond astrometry using observations of two bright asteroids with the same system on Apr 3, 2013. Strategies of scheduling observations to detect small and fast-moving NEAs with the synthetic tracking technique are discussed.

8 meters at 20 lunar distances. Not bad for a huge telescope.

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Yet Another Crackpot Superconductivity Theory Emerges

by Tommy on 20/03/2014

https://www.sciencemag.org/content/343/6177/1336.short

Angular Fluctuations of a Multicomponent Order Describe the Pseudogap of YBa2Cu3O6+x, Lauren E. Hayward, David G. Hawthorn, Roger G. Melko and Subir Sachdev, Science, Vol. 343 no. 6177 pp. 1336-1339, 21 March 2014

The hole-doped cuprate high-temperature superconductors enter the pseudogap regime as their superconducting critical temperature, Tc, falls with decreasing hole density. Recent x-ray scattering experiments in YBa2Cu3O6+x observe incommensurate charge-density wave fluctuations whose strength rises gradually over a wide temperature range above Tc, but then decreases as the temperature is lowered below Tc. We propose a theory in which the superconducting and charge-density wave orders exhibit angular fluctuations in a six-dimensional space. The theory provides a natural quantitative fit to the x-ray data and can be a basis for understanding other characteristics of the pseudogap.

Anything for a misleading press release. It’s like if you don’t have a theory, just make shit up!

Have you no shame, sir? Have you no sense of decency?

Room temperature superconductivity my ass.

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LRO Gigapan of the North Lunar Polar Region Released

by Tommy on 20/03/2014
LRO Lunar North Northern Pole Polar Gigapan Moon

LRO Lunar North Northern Pole Polar Gigapan Moon

http://lroc.sese.asu.edu/gigapan/

This should help out a lot. May the best pinnacle of eternal light win!

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Laser ARPES Detects Robust Electron Mode Coupling in a Pnictide High Temperature Superconductor

by Tommy on 19/03/2014

http://arxiv.org/abs/1403.3755

Evidence of a universal relation between electron-mode coupling and Tc in Ba1-xKxFe2As2 superconductor from Laser ARPES, W. Malaeb, T. Shimojima, Y. Ishida, T. Kondo, K. Okazaki, Y. Ota, K. Ohgushi, K. Kihou, C.H. Lee, A. Iyo, H. Eisaki, S. Ishida, M. Nakajima, S. Uchida, H. Fukazawa, T. Saito, Y. Kohori and S. Shin

We performed a Laser angle-resolved photoemission spectroscopy (ARPES) study on a wide doping range of Ba1-xKxFe2As2 (BaK) iron-based superconductor. We observed a robust low-binding energy (BE) kink structure in the dispersion which is doping dependent where its energy peaks at the optimally-doped (OP) level (x ~ 0.4) and decreases towards the underdoped (UD) and overdoped (OD) sides. It is also temperature-dependent and survives up to ~90K. We attribute this kink to electron-mode coupling in good agreement with the inelastic neutron scattering (INS) and scanning tunneling microscopy (STM) results on the same compound which observed a similar bosonic mode associated with spin excitations. The relation between the mode energy Ω and the SC transition temperature (Tc) deduced from our Laser ARPES data follow the universal relation deduced from INS and STM. In addition, we could resolve another kink at higher BE showing less doping and temperature dependence and may thus be of different origin.

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Optical Probe Confirms Mottness in High-Tc Superconductivity

by Tommy on 19/03/2014

http://arxiv.org/abs/1403.4092

Persistence of superconducting condensate far above the critical temperature in YBa2(Cu,Zn)3Oy revealed by c-axis optical conductivity measurements for several Zn concentrations and carrier doping levels, Ece Uykur, Kiyohisa Tanaka, Takahiko Masui, Shigeki Miyasaka and Setsuko Tajima, Accepted for Publication in Physical Review Letters

The superconductivity precursor phenomena in high temperature cuprate superconductors was studied by direct measurements of superconducting condensate with the use of the c-axis optical conductivity of YBa2(Cu,Zn)3Oy for several doping levels (p) as well as for several Zn-concentrations. Both of the real and imaginary part of the optical conductivity clearly showed that the superconducting carriers persist up to the high temperatures Tp that is higher than the critical temperature Tc but lower than the pseudogap temperature T. Tp increases with reducing doping level like T, but decreases with Zn-substitution unlike T.

Conclusions

These experimental facts put a strong constraint on the theory for high-Tc superconductivity. For example, preformed pairs predicted by the mean field theory of t-J model do not have phase coherence and thus they cannot explain our observation. Microscopically phase separated state in a doped Mott insulator is a more plausible candidate.

Recently the charge density wave (CDW) order was observed in the underdoped YBCO at the temperature close to our Tp. The simultaneous observation of a precursor of superconductivity and the CDW order suggests microscopic phase separation. Moreover, we may expect some interplay between these two orders although they originally compete with each other. To discuss the origin of this unusual precursor, the increase of Tp with decreasing the doping level is a smoking gun pointing to the importance of Mottness in the high-Tc superconductivity mechanism.

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Topological Insulators Are Efficient Thermoelectric Materials

by Tommy on 14/03/2014

http://arxiv.org/abs/1403.3137

Enhanced Thermoelectric Performance and Anomalous Seebeck Effects in Topological Insulators, Yong Xu, Zhongxue Gan and Shou-Cheng Zhang

Improving the thermoelectric figure of merit zT is one of the greatest challenges in material science. Recent discovery of topological insulators (TIs) offers new promise in this prospect. In this work, we demonstrate theoretically that zT is strongly size dependent in TI, and the size parameter can be tuned to enhance zT to be significantly greater than 1. Furthermore, we show that the life time of the edge states in TI is strongly energy dependent, leading to large and anomalous Seebeck effects with an opposite sign to the Hall effect. These striking properties make TIs the promising material for thermoelectrics science and technology.

Ok, here it comes … again! Who knew!

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Abiotic Atmospheres of Terrestrial Habitable Zone Planets

by Tommy on 13/03/2014

http://arxiv.org/abs/1403.2713

Abiotic oxygen-dominated atmospheres on terrestrial habitable zone planets, Robin Wordsworth and Raymond Pierrehumbert, Accepted for Publication in ApJ Letters

Detection of life on other planets requires identification of biosignatures, i.e., observable planetary properties that robustly indicate the presence of a biosphere. One of the most widely accepted biosignatures for an Earth-like planet is an atmosphere where oxygen is a major constituent. Here we show that lifeless habitable zone terrestrial planets around any star type may develop oxygen-dominated atmospheres as a result of water photolysis, because the cold trap mechanism that protects H2O on Earth is ineffective when the atmospheric inventory of non-condensing gases (e.g., N2, Ar) is low. Hence the spectral features of O2 and O3 alone cannot be regarded as robust signs of extraterrestrial life.

Cool! Or hot. Or not.

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Comets and Cometesimals Formed By Gravitational Instabilities

by Tommy on 13/03/2014

http://arxiv.org/abs/1403.2610

Comets formed in solar-nebula instabilities! – An experimental and modeling attempt to relate the activity of comets to their formation process, Jürgen Blum, Bastian Gundlach, Steffen Mühle and Josep M. Trigo-Rodriguez, Accepted by Icarus

When comet nuclei approach the Sun, the increasing energy flux through the surface layers leads to sublimation of the underlying ices and subsequent outgassing that promotes the observed emission of gas and dust. The ejection of dust requires that the forces binding the dust particles to the comet nucleus must be overcome by the forces caused by the sublimation process. This relates to the question of how large the tensile strength of the overlying dust layer is. Homogeneous layers of micrometer-sized dust particles reach tensile strengths of typically 103 to 104 Pa. This exceeds by far the maximum sublimation pressure of water ice in comets. It is therefore unclear how cometary dust activity is driven. To solve this paradox, we used the model by Skorov and Blum (Icarus 221, 1-11, 2012), who assumed that cometesimals formed by gravitational instability of a cloud of dust and ice aggregates and calculated for the corresponding structure of comet nuclei tensile strength of the dust-aggregate layers on the order of 1 Pa. Here we present evidence that the emitted cometary dust particles are indeed aggregates with the right properties to fit the model by Skorov and Blum. Then we experimentally measure the tensile strengths of layers of laboratory dust aggregates and confirm the values derived by the model. To explain the comet activity driven by the evaporation of water ice, we derive a minimum size for the dust aggregates of ∼1 mm, in agreement with meteoroid observations and dust-agglomeration models in the solar nebula. Finally we conclude that cometesimals must have formed by gravitational instability, because all alternative formation models lead to higher tensile strengths of the surface layers.

Wow. Weird. There’s treasure everywhere!

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Cuprate Pseudogap is Responsible for Broad Mid Infrared Band

by Tommy on 12/03/2014

http://arxiv.org/abs/1403.2887

Effect of the pseudogap on the infrared response in cuprate superconductors, Ling Qin, Jihong Qin and Shiping Feng

One of the most essential aspects of cuprate superconductors is a large pseudogap coexisting with a superconducting gap, then some anomalous properties can be understood in terms of the formation of the pseudogap. Within the kinetic energy driven superconducting mechanism, the effect of the pseudogap on the infrared response of cuprate superconductors in the superconducting-state is studied. By considering the interplay between the superconducting gap and pseudogap, the electron current-current correlation function is evaluated based on the linear response approach and it then is employed to calculate finite-frequency conductivity. It is shown that in the underdoped and optimally doped regimes, the transfer of the part of the low-energy spectral weight of the conductivity spectrum to the higher energy region to form a midinfrared band is intrinsically associated with the presence of the pseudogap.

What else could it be? Another mystery is laid bare by physics and mathematics!

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SpaceX Falcon 9 Reusable Launcher Does Marilyn Monroe

by Tommy on 12/03/2014
SpaceX Falcon 9 Reusable Launch Vehicle

SpaceX Falcon 9 Reusable Launch Vehicle

Perfect for your cubicle or cell wall.

Enjoy!

Update : If you do not get the joke here on multiple levels, then you are not a space cadet.

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Pulse Probe Spectroscopy Reveals Electron Boson Coupling

by Tommy on 10/03/2014

http://arxiv.org/abs/1403.1704

Witnessing the formation and relaxation of massive quasi-particles in a strongly correlated electron system, Fabio Novelli, Giulio De Filippis, Vittorio Cataudella, Martina Esposito, Ignacio Vergara Kausel, Federico Cilento, Enrico Sindici, Adriano Amaricci, Claudio Giannetti, Dharmalingam Prabhakaran, Simon Wall, Andrea Perucchi, Stefano Dal Conte, Giulio Cerullo, Massimo Capone, Andrey Mishchenko, Markus Grüninger, Naoto Nagaosa, Fulvio Parmigiani and Daniele Fausti

The non-equilibrium semiconductors physics is based on the paradigm that different degrees of freedom interact on different timescales. In this context the photo-excitation is often treated as an impulsive injection of electronic energy that is transferred to other degrees of freedom only at later times. Here, by studying the ultrafast particles dynamics in a archetypal strongly correlated charge-transfer insulator (La2CuO4), we show that the interaction between electrons and bosons manifest itself directly in the photo-excitation processes of a correlated material. With the aid of a general theoretical framework (Hubbard Holstein Hamiltonian), we reveal that sub-gap excitation pilots the formation of itinerant quasi-particles which are suddently dressed (<100 fs) by an ultrafast reaction of the bosonic field.

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CASIS Space Station Enabling Technologies Proposal Request

by Tommy on 7/03/2014

http://www.iss-casis.org/Opportunities/Solicitations/RFPEnablingTechnology.aspx

Enabling Technology To Support Science in Space For Life On Earth

RFP No. CASIS 2014-2 | RFP Issued: February 26, 2014 | Proposals Accepted: March 10, 2014
Step-1 Proposals Due: April 10, 2014 | Step-2 Proposals Due: June 27, 2014

The Center for the Advancement of Science in Space (CASIS) is pleased to announce a Request for Proposals (RFP) for flight projects to the International Space Station U.S. National Laboratory for both commercial and academic investigators. The purpose of this RFP is to solicit enabling technologies that increase the return on the U.S. investment in the ISS National Lab and enhance the value of uses of the space station research platform. To execute this mission, CASIS seeks technologies, research platforms, and operational concepts that enable new or improve existing analytical capabilities to benefit space science on the ISS National Lab for Earth benefit. CASIS will support this process through grant funding, facilitation of service-provider interactions, and flight coordination to and from the ISS National Lab.

This has been out for a couple of weeks but it officially starts Monday. I’m kinda pissed off about this and I promised myself I wouldn’t think about it, but nobody at CASIS is on my shit list right now that I know of. Who knows what going on with this, I haven’t even Wiki’d it yet, but it looks like they must be desperate for a zero-g rated induction oven at the very least. These people are just not serious, even Orbitec is flailing around. Quite honestly, this is nuts. Is that clear enough?

I’ll probably do one anyways. Let’s see, graboids, spheroids, cuboids, … no wait … crinoids!

The Space Colonization of Planet Earth

(manuscript in progress)

Update : Ok, that part was easy.

See also : The Future of Life on Earth

Update 2 : http://webpages.charter.net/tsiolkovsky/Space_Station.pdf

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According to Russian Investigators Hexagonal Diamond Lonsdaleite is Real

by Tommy on 7/03/2014

http://pubs.acs.org/doi/abs/10.1021/jz402528q

Lonsdaleite Films with Nanometer Thickness, Alexander G. Kvashnin and Pavel B. Sorokin, J. Phys. Chem. Lett., 5 (3), pp 541–548, 24 January 2014

We investigate the properties of potentially the stiffest quasi-2-D films with lonsdaleite structure. Using a combination of ab initio and empirical potential approaches, we analyze the elastic properties of lonsdaleite films in both elastic and inelastic regimes and compare them with graphene and diamond films. We review possible fabrication methods of lonsdaleite films using the pure nanoscale “bottom-up” paradigm: by connecting carbon layers in multilayered graphene. We propose the realization of this method in two ways: by applying direct pressure and by using the recently proposed chemically induced phase transition. For both cases, we construct the phase diagrams depending on temperature, pressure, and film thickness. Finally, we consider the electronic properties of lonsdaleite films and establish the nonlinear dependence of the band gap on the films’ thicknesses and their lower effective masses in comparison with bulk crystal.

Coming soon to an integrated circuit near you.

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SpaceX Considering Full Flow Gas Generator Methane Engine

by Tommy on 7/03/2014
Integrated Powerhead Demonstrator Prototype

Integrated Powerhead Demonstrator Prototype

1 million lbf per engine. Hopefully it scales down well, lol.

The hydrostatic bearings would be nice as well, if they work.

Like I said, I’m gonna need a bigger desert island. And earbuds.

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Martian Shergottite Meteorites May Be From Mojave Crater

by Tommy on 7/03/2014
Mojave Impact Crater Mars Shergottite Meteorite

Mojave Impact Crater Mars Shergottite Meteorite

https://www.sciencemag.org/content/early/2014/03/05/science.1247282.abstract

The Source Crater of Martian Shergottite Meteorites, Stephanie C. Werner, Anouck Ody and François Poulet, Science Express, 6 March 2014

Absolute ages for planetary surfaces are often inferred by crater densities and only indirectly constrained by the ages of meteorites. We show that the <5 million-year-old and 55-km-wide Mojave Crater is the ejection source for the meteorites classified as shergottites. Shergottites and this crater are linked by their coinciding meteorite ejection ages and the crater formation age, and mineralogical constraints. Because Mojave formed on 4.3 billion year old terrain, the original crystallization ages of shergottites are old, as inferred by Pb-Pb isotope ratios, and the much-quoted <600 million years shergottite ages are due to resetting. Thus, the cratering-based age determination method for Mars is now calibrated in situ, and shifts the absolute age of the oldest terrains of Mars backward by 200 million years.

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Disintegrating Volatile Asteroid P/2013 R3 Fragments Imaged

by Tommy on 6/03/2014
Disintegrating Asteroid MBC P 2013 R3

Disintegrating Asteroid MBC P 2013 R3

http://arxiv.org/abs/1403.1237

Disintegrating Asteroid P/2013 R3, David Jewitt, Jessica Agarwal, Jing Li, Harold Weaver, Max Mutchler and Stephen Larson, Accepted by ApJL

Splitting of the nuclei of comets into multiple components has been frequently observed but, to date, no main-belt asteroid has been observed to break-up. Using the Hubble Space Telescope, we find that main-belt asteroid P/2013 R3 consists of 10 or more distinct components, the largest up to 200 m in radius (assumed geometric albedo of 0.05) each of which produces a coma and comet-like dust tail. A diffuse debris cloud with total mass roughly 2×10^8 kg further envelopes the entire system. The velocity dispersion among the components is about V = 0.2 to 0.5 m/s, is comparable to the gravitational escape speeds of the largest members, while their extrapolated plane-of-sky motions suggest break-up between February and September 2013. The broadband optical colors are those of a C-type asteroid. We find no spectral evidence for gaseous emission, placing model-dependent upper limits to the water production rate near 1 kg/s. Breakup may be due to a rotationally induced structural failure of the precursor body.

I cannot hold it any longer, Captain! She’s gonna blow!

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The Existence of Hexagonal Diamond Lonsdaleite Questioned

by Tommy on 28/02/2014

http://adsabs.harvard.edu/abs/2013AGUFM.P41F1984N

Lonsdaleite has been used as an indicator of shock from cratering events, but does it exist?, P. Nemeth, L. A. Garvie and P. R. Buseck, American Geophysical Union, Fall Meeting 2013, abstract #P41F-1984

In 1967 a new diamond polymorph was described from the Canyon Diablo iron meteorite and called lonsdaleite (also referred to as hexagonal diamond. It was identified from reflections (e.g., at 0.218, 0.193, and 0.150 nm), additional to those in diamond, that were indexed in terms of a hexagonal cell. Lonsdaleite was attributed to shock-induced transformation of graphite within the iron meteorite upon impact and has subsequently been used as an indicator of shock and meteorite impact. Given the importance of lonsdaleite, we reinvestigated the structure of the shock-formed diamond and lonsdaleite from the Canyon Diablo meteorite with an aberration-corrected ultra-high-resolution scanning transmission electron microscope (STEM), with the view of providing further insights into the shock-forming mechanism. The STEM images allowed direct structural interpretation at 0.1-nm resolution and showed that the samples consist of single-crystal and twinned diamond, as well as graphite intimately associated at the nanoscale. A characteristic feature of the STEM images is stacking faults and twins (111, 200, 113) that interrupt the regularity of the crystal structure. Uncommon, subnanometer-sized regions occur with two- and four-layer hexagonal symmetry, though these regions merge into diamond with stacking faults. Although we did not find lonsdaleite, the defects can give rise to extra reflections like those attributed to lonsdaleite. For example, the (113) diamond twin results in a 0.216-nm spacing that matches that of the broad 0.218-nm lonsdaleite peak. Our observations from Canyon Diablo provide a new understanding of shocked diamond structures and question the existence of lonsdaleite and its inferred geologic implication, although the abundance of diamond twinning and stacking faults may be indicative of shock metamorphism.

See also :

http://ammin.geoscienceworld.org/content/99/2-3/531.abstract

Transformation of graphite to diamond via a topotactic mechanism, Laurence A.J. Garvie, Péter Németh and Peter R. Buseck, American Mineralogist, v. 99 no. 2-3 p. 531-538, February – March 2014

Several mechanisms and intermediate steps have been proposed to explain the transformation of graphite to diamond. However, the mechanism continues to be debated, in part because graphite that is incompletely transformed to diamond has not been reported; although such material could be used to better understand the diamond-forming process. Here we report the discovery of nano-sized grains of interstratified graphite and diamond from Gujba, an extraterrestrially shocked meteorite. We use high-resolution transmission electron microscopy (HRTEM) data from these grains to show that diamond formed via a reconstructive, topotactic rather than martensitic mechanism. Electron diffraction and HRTEM images show the following three-dimensional crystallographic relationships between the interstratified graphite and diamond: (001)g||(111)d, (100)g||(21̄1̄)d, and (12̄0)g||(01̄1)d. These relationships yield the transition matrix linking the graphite and diamond unit cells, which become coincident for graphite compressed to 7 GPa. The specific product, whether single-crystal or twinned diamond, is dictated by the initial graphite polytype and transformation route. The derivation of a three-dimensional transition matrix is consistent with a topotactic relationship between graphite and the newly formed diamond.

http://ammin.geoscienceworld.org/content/98/4/574.short

Transformation of graphite to lonsdaleite and diamond in the Goalpara ureilite directly observed by TEM, Yoshihiro Nakamuta and Shoichi Toh, American Mineralogist, v. 98 no. 4 p. 574-581, February – March 2014

This study reports on the structural relationship between graphite, lonsdaleite, and diamond extracted from the Goalpara ureilite and propose a model for the formation of lonsdaleite and diamond in these stony meteorites. The study is based on data from reflected-light microscopy and laser Raman spectroscopy of a polished thin section (PTS) of the Goalpara ureilite and X-ray powder diffraction (XRPD) analyses of the grains taken out of it. Selected-area electron diffraction (SAED) analyses and high-resolution TEM (HRTEM) observations were carried out in the three unique directions of pristine graphite with two thin slices prepared from a carbon grain directly taken out of a PTS. SAED patterns reveal the relative crystal-axes orientations between graphite (Gr), lonsdaleite (Lo), and diamond (Di) as (001)Gr//(100)Lo//(111)Di, [210]Gr//[001]Lo//[21̄1̄]Di, and (12̄0)Gr//(1̄20)Lo//(02̄2)Di. The shapes of diffraction spots in the SAED patterns reveal that the transformation of graphite to lonsdaleite and diamond is initiated by sliding of hexagonal carbon planes of graphite along the [210] of the graphite structure. These results suggest that lonsdaleite and diamond in ureilites formed directly from graphite through boat-type buckling and chair-type puckering of hexagonal carbon planes of graphite, respectively. The results of this study confirm the shock origin of diamond in ureilites.

So who didn’t see this coming? Kennett et al. are completely off the hook.

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There is No Pause or Hiatus in Global Warming. It’s a Myth.

by Tommy on 25/02/2014
There Is No Global Warming Pause Cowtan Way Tamino

There Is No Global Warming Pause Cowtan Way Tamino

http://tamino.wordpress.com/2014/01/30/global-temperature-the-post-1998-surprise/

http://onlinelibrary.wiley.com/doi/10.1002/qj.2297/abstract

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The BCS – BEC Crossover Transistion Reviewed

by Tommy on 24/02/2014

http://arxiv.org/abs/1402.5171

The BCS-BEC Crossover, Meera M. Parish, This article will be published as Chapter 9 in “Quantum gas experiments – exploring many-body states”, edited by P. Torma and K. Sengstock, Imperial College Press, London, to be published 2014

This chapter presents the crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly-correlated pairs of fermions to the Bose-Einstein condensation (BEC) of diatomic molecules in the atomic Fermi gas. Our aim is to provide a pedagogical review of the BCS-BEC crossover, with an emphasis on the basic concepts, particularly those that are not generally known or are difficult to find in the literature. We shall not attempt to give an exhaustive survey of current research in the limited space here; where possible, we will direct the reader to more extensive reviews.

A very nicely done modern review suitable for an advanced undergraduate course lecture.

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Planet Earth’s Newest Pinnacle of Feline Mammalian Evolution

by Tommy on 24/02/2014
Florida Everglades Rescued Panther Kitten

Florida Everglades Rescued Panther Kitten

Cute does not even begin to describe this guy.

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SpaceX Falcon 9 Reusable Launch Vehicle Shows A Little Leg

by Tommy on 23/02/2014
SpaceX Falcon 9 Reusable Launch Vehicle Landing Legs

SpaceX Falcon 9 Reusable Launch Vehicle Landing Legs

https://twitter.com/elonmusk/status/437761896028975104

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