ALBERT

Description: Author(s): M. Robinson, N. A. Marks, K. R. Whittle, and G. R. Lumpkin A generalized and systematic method of calculating threshold displacement energies ( E d ) using molecular dynamics simulations has been developed and applied to rutile TiO 2 . Statistically representative results have been achieved through fine sampling of impact energy and trajectory for each atomic sp... [Phys. Rev. B 85, 104105] Published Thu Mar 08, 2012

Description: Author(s): F. Marsusi and J. Sabbaghzadeh We have developed a theory of charge transport in a system of noninteracting polarons. The theory is conducted to a compact relation through a nonperturbative method based on electron-phonon Hamiltonian. The derived final result represents two different limits of band and phonon-assisted transport, ... [Phys. Rev. B 85, 115302] Published Thu Mar 08, 2012

Description: Author(s): Kazuhito Ohsawa, Keisuke Eguchi, Hideo Watanabe, Masatake Yamaguchi, and Masatoshi Yagi We present a first-principles study of stable configurations of single and multiple H atoms in a monovacancy in bcc transition metals and binding energies of the H atoms to the monovacancy. Typical bcc transition metals are group-V elements (V, Nb, and Ta), group-VI elements (Cr, Mo, and W), and Fe.... [Phys. Rev. B 85, 094102] Published Thu Mar 08, 2012

Description: Author(s): Miguel M. Ugeda, Iván Brihuega, Fanny Hiebel, Pierre Mallet, Jean-Yves Veuillen, José M. Gómez-Rodríguez, and Félix Ynduráin We provide a thorough study of a carbon divacancy, a point defect expected to have a large impact on the properties of graphene. Low-temperature scanning tunneling microscopy imaging of irradiated graphene on different substrates enabled us to identify a common twofold symmetry point defect. Our fir... [Phys. Rev. B 85, 121402] Published Thu Mar 08, 2012

Description: Author(s): Cheng Gong, Jiaming Jiang, Chuang Li, Liwei Song, Zhinan Zeng, Jing Miao, Xiaochun Ge, Yinghui Zheng, Ruxin Li, and Zhizhan Xu High-order harmonics were generated with neon gas by using 12-fs midinfrared laser pulses with stabilized carrier-envelope phase (CEP). At some specific CEP, a broad “supercontinuum” of the extreme ultraviolet spectrum can be obtained. Two distinct continuous spectral regimes are found by numerical ... [Phys. Rev. A 85, 033410] Published Thu Mar 08, 2012

Description: Author(s): Y. Zeng, D. A. R. Dalvit, J. O'Hara, and S. A. Trugman We apply a rigorous eigenmode analysis to study the electromagnetic properties of linear and weakly nonlinear metamaterials. The nonlinear response can be totally described by the linear eigenmodes when weak nonlinearities are attributed to metamaterials. We use this theory to interpret intrinsic se... [Phys. Rev. B 85, 125107] Published Thu Mar 08, 2012

Description: Author(s): R. B. Neufeld Jet momentum balance measurements, such as those recently performed by the CMS collaboration, provide an opportunity to quantify the energy transferred from a parton shower to the underlying medium in heavy-ion collisions. Specifically, I argue that the Cooper-Frye freeze-out distribution associated... [Phys. Rev. C 85, 034903] Published Thu Mar 08, 2012

Description: Author(s): Mayumi Aoki, Shinya Kanemura, and Kei Yagyu In general, there can be mass differences among scalar bosons of the Higgs triplet field with the hypercharge of Y =1 . In the Higgs triplet model, when the vacuum expectation value v Δ of the triplet field is much smaller than that v ( ≃246  GeV ) of the Higgs doublet field as required by the electrowea... [Phys. Rev. D 85, 055007] Published Thu Mar 08, 2012

Description: Author(s): Daichi Kashino, Kiyotomo Ichiki, and Tsutomu T. Takeuchi The standard models of inflation predict statistically homogeneous and isotropic primordial fluctuations, which should be tested by observations. In this paper we illustrate a method to test the statistical isotropy of the mean of the cosmic microwave background temperature fluctuations in the spher... [Phys. Rev. D 85, 063001] Published Thu Mar 08, 2012

Description: Author(s): Jean-François Fortin and Tim M. P. Tait Dark matter which interacts through a magnetic or electric dipole moment is an interesting possibility which may help resolve the discrepancy between the DAMA annual modulation signal and the null results of other searches. In this article we examine relic density and collider constraints on such da... [Phys. Rev. D 85, 063506] Published Thu Mar 08, 2012

Description: Author(s): A. S. Sefiedgar, Z. Haghani, and H. R. Sepangi The collision-free Boltzmann equation is used in the context of brane- f ( R ) gravity to derive the virial theorem. It is shown that the virial mass is proportional to certain geometrical terms appearing in the Einstein field equations and contributes to gravitational energy and that such a geometric m... [Phys. Rev. D 85, 064012] Published Thu Mar 08, 2012

Description: Author(s): Laur Järv, Piret Kuusk, and Margus Saal We consider flat Friedmann-Lemaître-Robertson-Walker cosmological models in the framework of general scalar-tensor theories of gravity with arbitrary coupling functions, set in the Jordan frame, in the cosmological epoch when the energy density of the ordinary dust matter dominates over the energy d... [Phys. Rev. D 85, 064013] Published Thu Mar 08, 2012

Description: Author(s): Christian Pfeifer and Mattias N. R. Wohlfarth We construct gravitational dynamics for Finsler spacetimes in terms of an action integral on the unit tangent bundle. These spacetimes are generalizations of Lorentzian metric manifolds which satisfy necessary causality properties. A coupling procedure for matter fields to Finsler gravity completes ... [Phys. Rev. D 85, 064009] Published Thu Mar 08, 2012

Description: Author(s): Robert H. Coridan, Nathan W. Schmidt, Ghee Hwee Lai, Peter Abbamonte, and Gerard C. L. Wong Nanoconfined water and surface-structured water impacts a broad range of fields. For water confined between hydrophilic surfaces, measurements and simulations have shown conflicting results ranging from “liquidlike” to “solidlike” behavior, from bulklike water viscosity to viscosity orders of magnit... [Phys. Rev. E 85, 031501] Published Thu Mar 08, 2012

Description: Author(s): Jacob Judas Kain Kirkensgaard Using dissipative particle dynamics simulations we give numerical evidence of the formation of “striped” (or A B alternating) diamond and gyroid network structures and other hierarchical morphologies in A m B m C n ( 2 m + n )-miktoarm star terpolymers where the main variable is the ratio x = n / m with m , n being ... [Phys. Rev. E 85, 031802] Published Thu Mar 08, 2012

Description: Author(s): Christophe Letellier and Luis A. Aguirre After suggesting criteria to recognize a new system and a new attractor—and to make a distinction between them—the paper details the topological analysis of the “cord” attractor. This attractor, which resembles a cord between two leaves, is produced by a three-dimensional system that is obtained aft... [Phys. Rev. E 85, 036204] Published Thu Mar 08, 2012

Description: Author(s): Merced Montesinos and Mercedes Velázquez We perform the coupling of the scalar, Maxwell, and Yang-Mills fields as well as the cosmological constant to BF gravity with Immirzi parameter. The proposed action principles employ auxiliary fields in order to keep a polynomial dependence on the B fields. By handling the equations of motion for th... [Phys. Rev. D 85, 064011] Published Thu Mar 08, 2012

Description: Author(s): Ian Huston and Adam J. Christopherson Isocurvature perturbations naturally occur in models of inflation consisting of more than one scalar field. In this paper, we calculate the spectrum of isocurvature perturbations generated at the end of inflation for three different inflationary models consisting of two canonical scalar fields. The ... [Phys. Rev. D 85, 063507] Published Thu Mar 08, 2012

Description: Author(s): J. M. Pedrosa, D. Wisniacki, G. G. Carlo, and M. Novaes We investigate the properties of the semiclassical short periodic orbit approach for the study of open quantum maps that was recently introduced [ Novaes, Pedrosa, Wisniacki, Carlo and Keating Phys. Rev. E 80 035202 (2009) ]. We provide solid numerical evidence, for the paradigmatic systems of the o... [Phys. Rev. E 85, 036203] Published Thu Mar 08, 2012

Description: Author(s): H. Reinholz and G. Röpke Calculating the frequency-dependent dielectric function for strongly coupled plasmas, the relations within kinetic theory and linear response theory are derived and discussed in comparison. In this context, we give a proof that the Kohler variational principle can be extended to arbitrary frequencie... [Phys. Rev. E 85, 036401] Published Thu Mar 08, 2012

Description: Author(s): Elijah Flenner, Lorant Janosi, Bogdan Barz, Adrian Neagu, Gabor Forgacs, and Ioan Kosztin Computer modeling of multicellular systems has been a valuable tool for interpreting and guiding in vitro experiments relevant to embryonic morphogenesis, tumor growth, angiogenesis and, lately, structure formation following the printing of cell aggregates as bioink particles. Here we formulate two ... [Phys. Rev. E 85, 031907] Published Thu Mar 08, 2012

Description: Author(s): J. F. Barry, E. S. Shuman, E. B. Norrgard, and D. DeMille We demonstrate deceleration of a beam of neutral strontium monofluoride molecules using radiative forces. Under certain conditions, the deceleration results in a substantial flux of detected molecules with velocities ≲50  m/s . Simulations and other data indicate that the detection of molecules below... [Phys. Rev. Lett. 108, 103002] Published Thu Mar 08, 2012

Description: Author(s): Intae Eom, Sung-Hyun Ahn, Hanju Rhee, and Minhaeng Cho We demonstrate that a single-pulse characterization of electronic optical activity-free induction decay, which carries information on both circular dichroism and optical rotatory dispersion, is experimentally feasible. Employing a self-referencing scheme, we show that a highly reliable interferometr... [Phys. Rev. Lett. 108, 103901] Published Thu Mar 08, 2012

Description: Author(s): C. Cremaschini, M. Tessarotto, and J. C. Miller This Letter presents a kinetic description of low-frequency and long-wavelength axisymmetric electromagnetic perturbations in nonrelativistic, strongly magnetized, and gravitationally bound axisymmetric accretion-disk plasmas in the collisionless regime. The analysis, carried out within the framewor... [Phys. Rev. Lett. 108, 101101] Published Thu Mar 08, 2012

Description: Author(s): B. Isham, M. T. Rietveld, P. Guio, F. R. E. Forme, T. Grydeland, and E. Mjølhus Langmuir cavitons have been artificially produced in Earth’s ionosphere, but evidence of naturally occurring cavitation has been elusive. By measuring and modeling the spectra of electrostatic plasma modes, we show that natural cavitating, or strong, Langmuir turbulence does occur in the ionosphere,... [Phys. Rev. Lett. 108, 105003] Published Thu Mar 08, 2012

Description: Author(s): Rene Ledesma-Alonso, Dominique Legendre, and Philippe Tordjeman We study the interaction between a solid particle and a liquid interface. A semianalytical solution of the nonlinear equation that describes the interface deformation points out the existence of a bifurcation behavior for the apex deformation as a function of the distance. We show that the apex curv... [Phys. Rev. Lett. 108, 106104] Published Thu Mar 08, 2012

Description: Author(s): Eran Katzir, Shira Yochelis, Felix Zeides, Nadav Katz, Yaov Kalcheim, Oded Millo, Gregory Leitus, Yuri Myasodeyov, Boris Ya. Shapiro, Ron Naaman, and Yossi Paltiel The superconducting critical temperature, T C , of thin Nb films is significantly modified when gold nanoparticles (NPs) are chemically linked to the Nb film, with a consistent enhancement when using 3 nm long disilane linker molecules. The T C increases by up to 10% for certain linker length and NP si... [Phys. Rev. Lett. 108, 107004] Published Thu Mar 08, 2012

Description: Author(s): J. O. Daldrop, C. T. H. Davies, and R. J. Dowdall (HPQCD Collaboration) We calculate the full spectrum of D -wave states in the Υ system in lattice QCD for the first time, by using an improved version of nonrelativistic QCD on coarse and fine “second-generation” gluon field configurations from the MILC Collaboration that include the effect of up, down, strange, and charm... [Phys. Rev. Lett. 108, 102003] Published Thu Mar 08, 2012

Description: Author(s): Vernon Barger, Muneyuki Ishida, and Wai-Yee Keung A number of candidate theories beyond the standard model (SM) predict new scalar bosons below the TeV region. Among these, the radion, which is predicted in the Randall-Sundrum model, and the dilaton, which is predicted by the walking technicolor theory, have very similar couplings to those of the S... [Phys. Rev. Lett. 108, 101802] Published Thu Mar 08, 2012

Description: Author(s): Soohyung Park, Taehoon Kim, and Wonpil Im A method of window exchange umbrella sampling molecular dynamics simulation is employed for transmembrane helix assembly. An analytical expression for the average acceptance probability between neighboring windows is derived and combined with the first passage time optimization method to predetermin... [Phys. Rev. Lett. 108, 108102] Published Thu Mar 08, 2012

Description: Author(s): Per Sebastian Skardal, Alain Karma, and Juan G. Restrepo Spatially discordant alternans is a widely observed pattern of voltage and calcium signals in cardiac tissue that can precipitate lethal cardiac arrhythmia. Using spatially coupled iterative maps of the beat-to-beat dynamics, we explore this pattern’s dynamics in the regime of a calcium-dominated pe... [Phys. Rev. Lett. 108, 108103] Published Thu Mar 08, 2012

Description: Author(s): Marcos Verissimo-Alves, Pablo García-Fernández, Daniel I. Bilc, Philippe Ghosez, and Javier Junquera We report first-principles characterization of the structural and electronic properties of (SrTiO 3 ) 5 /(SrRuO 3 ) 1 superlattices. We show that the system exhibits a spin-polarized two-dimensional electron gas, extremely confined to the 4 d orbitals of Ru in the SrRuO 3 layer. Every interface in the superl... [Phys. Rev. Lett. 108, 107003] Published Thu Mar 08, 2012

Description: Author(s): Yuhou Wang, Walter Gekelman, Patrick Pribyl, and Konstantinos Papadopoulos Laboratory observations of enhanced loss of fast electrons trapped in a magnetic mirror geometry irradiated by shear Alfvén waves (SAW) are reported. A population of runaway electrons generated by second harmonic electron-cyclotron-resonance heating, as evidenced by the production of hard x rays wit... [Phys. Rev. Lett. 108, 105002] Published Thu Mar 08, 2012

Description: Author(s): Filipe Tostevin, Wiet de Ronde, and Pieter Rein ten Wolde In biochemical signaling, information is often encoded in oscillatory signals. However, the advantages of such a coding strategy over an amplitude-encoding scheme of constant signals remain unclear. Here we study the dynamics of a simple model gene promoter in response to oscillating and constant tr... [Phys. Rev. Lett. 108, 108104] Published Thu Mar 08, 2012

Description: Author(s): Timothy H. Hsieh and Liang Fu The recently discovered superconductor Cu x Bi 2 Se 3 is a candidate for three-dimensional time-reversal-invariant topological superconductors, which are predicted to have robust surface Andreev bound states hosting massless Majorana fermions. In this work, we analytically and numerically find the linear... [Phys. Rev. Lett. 108, 107005] Published Thu Mar 08, 2012

Description: Author(s): Igor Popov, Nadjib Baadji, and Stefano Sanvito We report on a density functional theory study demonstrating the coexistence of weak ferromagnetism and antiferroelectricity in boron-deficient MgB 6 . A boron vacancy produces an almost one dimensional extended molecular orbital, which is responsible for the magnetic moment formation. Then, long-rang... [Phys. Rev. Lett. 108, 107205] Published Thu Mar 08, 2012

Description: Author(s): P. Honvault, M. Jorfi, T. González-Lezana, A. Faure, and L. Pagani [Phys. Rev. Lett. 108, 109903] Published Thu Mar 08, 2012

Description: Publication year: 2012 Source: Quaternary Research R. Jayangondaperumal, M.K. Murari, P. Sivasubramanian, N. Chandrasekar, A.K. Singhvi The Holocene and late Pleistocene environmental history of the teri (‘sandy waste’ in local parlance) red sands in the southeast coastal Tamil Nadu was examined using remote sensing, stratigraphy, and optically stimulated luminescence (OSL) dating. Geomorphological surveys enabled the classification of the teri red sands as, 1) inland fluvial teri, 2) coastal teri and, 3) near-coastal teri dunes. The inland teri sediments have higher clay and silty-sand component than the coastal and near-coastal teri, suggesting that these sediments were deposited by the fluvial process during a stronger winter monsoon around 〉 15 ka. The coastal teri dunes were deposited prior to 11.4 ± 0.9 ka, and the near-coastal dunes aggraded at around 5.6 ± 0.4 ka. We interpret that the coastal dunes were formed during a period of lower relative sea level and the near-coastal dunes formed during a period of higher sea level. Dune reddening is post deposition occurred after 11.4 ± 0.9 ka for the coastal teri dunes and after 5.6 ± 0.4 ka for the near-coastal teri dunes. Presence of microlithic sites associated with the coastal dunes suggest that the cultures existed in the region during 11.4 ± 0.9 ka and 5.6 ± 0.4 ka.

Description: Publication year: 2012 Source: Quaternary Research Bradley E. Blumer, Alan F. Arbogast, Steven L. Forman Extensive coastal dunes occur in the Great Lakes region of North America, including northwestern Michigan where some are perched on high (~ 100 m) bluffs. This study focuses on such a system at Arcadia Dunes and is the first to systematically generate optical ages from stratigraphic sections containing buried soils. Dune growth began ca. 4.5 ka during the Nipissing high lake stand and continued episodically thereafter, with periods of increased sand supply at ca. 3.5 ka and ca. 1.7 ka. The most volumetrically dominant phase of dune growth began ca. 1.0 ka and continued intermittently for about 500 years. It may have begun due to the combined effects of a high lake phase, potential changes in lake hydrodynamics with final isostatic separation of Lake Superior from Lakes Michigan and Huron, and increased drought and hydrologic variability associated with the Medieval Warm Period. Thus, this latest eolian phase likely reflects multiple processes associated with Great Lakes water level and climate variability that may also explain older eolian depositional events. Comparison of Arcadia ages and calendar corrected 14 C ages from previous studies indicate broad chronological agreement between events at all sites, although it appears that dune growth began later at Arcadia.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Miguel Cortés Sánchez, Francisco J. Jiménez Espejo, María D. Simón Vallejo, Juan F. Gibaja Bao, António Faustino Carvalho, Francisca Martinez-Ruiz, Marta Rodrigo Gamiz, José-Abel Flores, Adina Paytan, José A. López Sáez, Leonor Peña-Chocarro, José S. Carrión, Arturo Morales Muñiz, Eufrasia Roselló Izquierdo, José A. Riquelme Cantal, Rebecca M. Dean, Emília Salgueiro, Rafael M. Martínez Sánchez, Juan J. De la Rubia de Gracia, María C. Lozano Francisco, José L. Vera Peláez, Laura Llorente Rodríguez, Nuno F. Bicho New data and a review of historiographic information from Neolithic sites of the Malaga and Algarve coasts (southern Iberian Peninsula) and from the Maghreb (North Africa) reveal the existence of a Neolithic settlement at least from 7.5 cal ka BP. The agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the Mesolithic populations. The timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems, including upwelling intensity, sea-level changes and increased aridity in the Sahara and along the Iberian coast. These changes likely impacted the subsistence strategies of the Mesolithic populations along the Iberian seascapes and resulted in abandonments manifested as sedimentary hiatuses in some areas during the Mesolithic–Neolithic transition. The rapid expansion and area of dispersal of the early Neolithic traits suggest the use of marine technology. Different evidences for a Maghrebian origin for the first colonists have been summarized. The recognition of an early North-African Neolithic influence in Southern Iberia and the Maghreb is vital for understanding the appearance and development of the Neolithic in Western Europe. Our review suggests links between climate change, resource allocation, and population turnover.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Ignacio A. Jara, Patricio I. Moreno We present detailed pollen and charcoal records from Lago Pichilafquén (~ 41°S) to decipher the effects of climate change and varying disturbance regimes on the composition and structure of the vegetation on the Andean foothills of northwestern Patagonia during the last 2600 yr. Here, temperate rainforests have dominated the landscape since 2600 cal yr BP with variations ranging from cool-temperate and wet north Patagonian rainforests to relatively warm and summer-drought-resistant Valdivian rainforests. We interpret relatively warm/dry conditions between 1900–2600, 690–750 and 320–430 cal yr BP, alternating with cold/wet conditions between 1500–1900, 750–1100 and 430–690 cal yr BP. Rapid deforestation and spread of plants introduced by Europeans occurred at 320 and 140 cal yr BP. The record includes five tephras with ages of 2130, 1460, 1310, 1210, and 340 cal yr BP, all of which precede local fire events and increases in trees favored by disturbance by less than 100 yr. We conclude that centennial-scale changes in the southern westerlies were the primary driver of vegetation shifts in northwestern Patagonia over the last 2600 yr. Within this interval, local disturbance regimes altered the structure, composition, and dynamics of the lowland rainforest vegetation during several discrete, short-lived episodes.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Warren W. Wood, Richard M. Bailey, Brian A. Hampton, Thomas F. Kraemer, Zhong Lu, David W. Clark, Rhodri H.R. James, Khalid Al Ramadan The coastline along the southern Arabian Gulf between Al Jubail, Kingdom of Saudi Arabia, and Dubai, UAE, appears to have risen at least 125 m in the last 18,000 years. Dating and topographic surveying of paleo-dunes (43–53 ka), paleo-marine terraces (17–30 ka), and paleo-marine shorelines (3.3–5.5 ka) document a rapid, 〉 1 mm/a subsidence, followed by a 6 mm/a uplift that is decreasing with time. The mechanism causing this movement remains elusive but may be related to the translation of the coastal area through the backbasin to forebulge hinge line movement of the Arabian plate or, alternatively, by movement of the underlying Infracambrian-age Hormuz salt in response to sea-level changes associated with continental glaciation. Independent of the mechanism, rapid and episodic uplift may impact the design of engineering projects such as nuclear power plants, airports, and artificial islands as well as the interpretation of sedimentation and archeology of the area.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Ryszard K. Borówka, Wacław Strobel, Stanisław Hałas The environmental conditions of the Szczecin Bay, which existed prior to Szczecin Lagoon, have been reconstructed on the basis of the stable carbon and oxygen isotope ( 18 O and 13 C) analysis and radiocarbon dates obtained for subfossil shells of Cerastoderma (Cardium) glaucum . The shells in the collected core were well preserved in their life positions, representing a geochemical record of past temperature variation over the middle Holocene. Three major periods with different thermal conditions have been distinguished in the interval ~ 6000–4300 cal yr BP, when the important Littorina regional transgression took place. During the first period, 6000–5250 cal yr BP, water temperature decreased by 1.4°C, and then remained constant over the second period (5250–4750 cal yr BP). In contrast, during the third period (4750–4300 cal yr BP) both δ-values were highly variable and the mean summer temperature (March–November) increased by about 3.5°C. During first two periods, δ 18 O and δ 13 C were significantly correlated, indicating stability of the environmental conditions.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Georg Irion, Jáder Onofre de Morais, Friederike Bungenstock Beach-rock exposures provide a record of Holocene sea-level rise along the 560-km-long northeast-facing coast of Ceará, Brazil, that differs from the record available along the other 4300 km of Brazilian coastline further south. Whereas documentation is available from southern Brazil to show Holocene sea levels as much as 5 m above today's level, our observations along the northeastern coast indicate that sea level here was not above the present-day level during the Holocene. Near Jericoacoara, about 240 km northwest of Fortaleza, characterized by strong surf, Precambrian rocks crop out from under a temporary cover of sand in small protected locations with less surf. Here in this upper tidal zone beach rock is being formed, while it is being dismembered synchronously by erosion at lower tide levels. This shows a rising sea level. Along the entire coast of Ceará west of Ponta Grossa the absence of beach rock higher than spring tide level indicates that sea-level was not above its present-day level during the Holocene. Notches in bedrock situated between 2 m and 6 m above spring-tide high-water level that we formerly described as Holocene, are now believed to be Sangamonian.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Roland Zech Surface exposure dating has become a helpful tool for establishing numeric glacial chronologies, particularly in arid high-mountain regions where radiocarbon dating is challenging due to limited availability of organic material. This study presents 13 new 10 Be surface exposure ages from the Kitschi-Kurumdu Valley in the At Bashi Range, Tien Shan. Three moraines were dated to ~ 15, 21 and 〉 56 ka, respectively, and corroborate previous findings that glacial extents in the Tien Shan during Marine Oxygen Isotope Stage (MIS) 2 were limited compared to MIS 4. This likely documents increasingly arid conditions in Central Asia during the last glacial cycle. Morphological evidence in the Kitschi-Kurumdu Valley and a detailed review of existing numeric glacial chronologies from the Tien Shan indicate that remnants of the penultimate glaciation (MIS 6) are preserved, whereas evidence for MIS 5 glacier advances remains equivocal. Reviewed and recalculated exposure ages from the Pamir mountains, on the other hand, reveal extensive MIS 5 glacial extents that may indicate increased monsoonal precipitation. The preservation of MIS 3 moraines in the Tien Shan and the southern Pamir does not require any monsoonal influence and can be explained alternatively with increased precipitation via the westerlies.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Antonio González-Ramón, Bartolomé Andreo, Antonio Ruiz-Bustos, David A. Richards, José Antonio López-Sáez, Francisca Alba-Sánchez Cucú cave is a small cavity, 1600 m above sea level on the southern slope of Sierra de María (Almería Province, SE Spain), where current mean annual precipitation is 〈 450 mm. Fossils and palynomorphs contained within a sedimentary sequence, up to 9 m in depth, allow us to consider the prevailing climatic conditions, and the timing of cavern development. The lithological sequence is dominated by clast-supported detrital material with no evidence of alluvial transport. These sediments were formed by freeze-cracking during periglacial conditions, causing further cave enlargement after initial solutional development. The clastic sequence formed during cold climates is covered by a flowstone that was deposited during a period of warmer, wetter conditions. This provides a minimum U–Th isochron age of 40.2 ± 4.5 ka for the timing of periglacial action. Micromammal fossil species indicate a chronology between 140 and 80 ka. Paleoecological data based on the structure of the mammal community indicates that cold conditions prevailed at the time of deposit. In the studied sequence the presence of anthropogenic components has not been documented. The pollen assemblages identified are a common feature of Pleistocene cold stages that are in semi-arid regions.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Aya Schneider Mor, Ruth Yam, Cristina Bianchi, Martina Kunz-Pirrung, Rainer Gersonde, Aldo Shemesh The relationships among internally consistent records of summer sea-surface temperature (SSST), winter sea ice (WSI), and diatomaceous stable isotopes were studied across seven terminations over the last 660 ka in sedimentary cores from ODP sites 1093 and 1094. The sequence of events at both sites indicates that SSST and WSI changes led the carbon and nitrogen isotopic changes in three Terminations (TI, TII and TVI) and followed them in the other four Terminations (TIII, TIV, TV and TVII). In both TIII and TIV, the leads and lags between the proxies were related to weak glacial mode, while in TV and TVII they were due to the influence of the mid-Pleistocene transition. We show that the sequence of events is not unique and does not follow the same pattern across terminations, implying that the processes that initiated climate change in the Southern Ocean has varied through time.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Martina Demuro, Duane G. Froese, Lee J. Arnold, Richard G. Roberts Improved chronological control on the penultimate advance of the Cordilleran Ice Sheet in northwest Canada (the Reid glaciation) is required for a better understanding of late Quaternary palaeoclimatic and palaeoenvironmental change in eastern Beringia. However, reliable dating of glaciation events beyond the last glacial maximum is commonly hindered by a lack of directly dateable material. In this study we (i) provide the first combined minimum and maximum age constraint on the Reid glaciation at Ash Bend, its reference locale in the Stewart River valley, northwestern Canadian Cordillera, using single-grain optically stimulated luminescence dating of quartz; and (ii) compare the timing of the Reid glaciation with other penultimate ice sheet advances in the region with the aim of establishing improved glacial reconstructions in eastern Beringia. We obtain ages of 158 ± 18 ka and 132 ± 18 ka for glaciofluvial sands overlying and underlying the Reid till, respectively. These ages indicate that the Reid advance, at its reference locale, occurred during MIS 6. This precludes an earlier MIS 8 age, and suggests that the Reid advance may have been synchronous with the Delta glaciation of central Alaska, and is likely correlative with the Mirror Creek glaciation in southern Yukon.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Patrick J. Applegate, Nathan M. Urban, Klaus Keller, Thomas V. Lowell, Benjamin J.C. Laabs, Meredith A. Kelly, Richard B. Alley The statistical distributions of cosmogenic nuclide measurements from moraine boulders contain previously unused information on moraine ages, and they help determine whether moraine degradation or inheritance is more important on individual moraines. Here, we present a method for extracting this information by fitting geomorphic process models to observed exposure ages from single moraines. We also apply this method to 94 10 Be apparent exposure ages from 11 moraines reported in four published studies. Our models represent 10 Be accumulation in boulders that are exhumed over time by slope processes (moraine degradation), and the delivery of boulders with preexisting 10 Be inventories to moraines (inheritance). For now, we neglect boulder erosion and snow cover, which are likely second-order processes. Given a highly scattered data set, we establish which model yields the better fit to the data, and estimate the age of the moraine from the better model fit. The process represented by the better-fitting model is probably responsible for most of the scatter among the apparent ages. Our methods should help resolve controversies in exposure dating; we reexamine the conclusions from two published studies based on our model fits.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Joanne S. Johnson, Jeremy D. Everest, Philip T. Leat, Nicholas R. Golledge, Dylan H. Rood, Finlay M. Stuart Recent changes along the margins of the Antarctic Peninsula, such as the collapse of the Wilkins Ice Shelf, have highlighted the effects of climatic warming on the Antarctic Peninsula Ice Sheet (APIS). However, such changes must be viewed in a long-term (millennial-scale) context if we are to understand their significance for future stability of the Antarctic ice sheets. To address this, we present nine new cosmogenic 10 Be exposure ages from sites on NW Alexander Island and Rothschild Island (adjacent to the Wilkins Ice Shelf) that provide constraints on the timing of thinning of the Alexander Island ice cap since the last glacial maximum. All but one of the 10 Be ages are in the range 10.2–21.7 ka, showing a general trend of progressive ice-sheet thinning since at least 22 ka until 10 ka. The data also provide a minimum estimate (490 m) for ice-cap thickness on NW Alexander Island at the last glacial maximum. Cosmogenic 3 He ages from a rare occurrence of mantle xenoliths on Rothschild Island yield variable ages up to 46 ka, probably reflecting exhumation by periglacial processes.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Nan Jia, Yuhong Wang, Liguang Sun Large desiccation cracks were discovered in the intertidal zone of Zhoushan archipelago, East China Sea. Radiocarbon dating showed that desiccation cracks were formed around 31.2–30.4 cal ka BP. Palynological, mineralogical, and elemental geochemical analyses indicated that the cracks were formed as the result of an abrupt climate shift event. The climate changed from warm and humid, to cold and arid, and back to warm and humid again. This climate event is quite likely linked to Heinrich event 3 via the East Asian Monsoon. Desiccation cracks may provide a new proxy material for studying paleoclimate and paleoenvironment in the Quaternary.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 B. Brandon Curry, Michael E. Konen, Timothy H. Larson, Catherine H. Yansa, Keith C. Hackley, Thomas V. Lowell, Justine Petras

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Jason A. Rech, Jeffrey C. Nekola, Jeffrey S. Pigati Analysis of terrestrial gastropods that underlie the late Pleistocene Two Creeks forest bed (~ 13,800–13,500 cal yr BP) in eastern Wisconsin, USA provides evidence for a mixed tundra-taiga environment prior to formation of the taiga forest bed. Ten new AMS 14 C analyses on terrestrial gastropod shells indicate the mixed tundra-taiga environment persisted from ~ 14,500 to 13,900 cal yr BP. The Twocreekan climatic substage, representing ice-free conditions on the shore of Lake Michigan, therefore began near the onset of peak warming conditions during the Bølling–Allerød interstadial and lasted ~ 1000 yr, nearly 600 yr longer than previously thought. These results provide important data for understanding the response of continental ice sheets to global climate forcing and demonstrate the potential of using terrestrial gastropod fossils for both environmental reconstruction and age control in late Quaternary sediments.

Description: Publication year: 2012 Source: Quaternary Research Huayu Lu, Yali Zhou, Weiguo Liu, Joseph Mason Vegetation changes during the late Quaternary in the dune fields of northern China are not well understood. We investigated organic carbon stable isotopic composition of surface soils, related mainly to the ratio of C 3 and C 4 plants, across a range of arid to subhumid climates in this region. Isotopic composition is weakly related to both temperature and moisture (multiple R 2 = 0.53), with the highest δ 13 C (greatest C 4 abundance) in the warm, subhumid Horqin dune field. In late Quaternary, eolian stratigraphic sections of the Mu Us and Horqin dune fields, but not in the much colder Otindag dune field, δ 13 C is higher in organic carbon from paleosols than in eolian sands. This contrast, most evident for paleosols recording a major early to middle Holocene phase of dune stabilization, is interpreted as evidence for expansion of C 4 plants due to increased effective moisture, high temperature because of high insolation, and decreased disturbance related to eolian erosion and deposition.

Description: Publication year: 2012 Source: Quaternary Research Michel Magny, Sébastien Joannin, Didier Galop, Boris Vannière, Jean Nicolas Haas, Michele Bassetti, Paolo Bellintani, Romana Scandolari, Marc Desmet A lake-level record of Lake Ledro (northern Italy) spans the entire Holocene with a chronology derived from 51 radiocarbon dates. It is based on a specific sedimentological approach that combines data from five sediment profiles sampled in distinct locations in the littoral zone. On a millennial scale, the lake-level record shows two successive periods from 11,700 to 4500 cal yr BP and from 4500 cal yr BP to the present, characterized by lower and higher average lake levels, respectively. In addition to key seasonal and inter-hemispherical changes in insolation, the major hydrological change around 4500 cal yr BP may be related to a non-linear response of the climate system to orbitally-driven gradual decrease in insolation. The Ledro record questions the notion of an accentuated summer rain regime in the northern Mediterranean borderlands during the boreal insolation maximum. Moreover, the Ledro record highlights that the Holocene was punctuated by successive centennial-scale highstands. Correlations with the Preboreal oscillation and the 8.2 ka event, and comparison with the atmospheric 14 C residual record, suggest that short-lived lake-level fluctuations developed at Ledro in response to (1) final steps of the deglaciation in the North Atlantic area and (2) variations in solar activity.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Michael Iannicelli

Description: Publication year: 2012 Source: Quaternary Research Brandi Bracht-Flyr, Sherilyn C. Fritz Late-Holocene environmental and climatic conditions were reconstructed from diatom assemblages in sediment cores from four western Montana lakes: Crevice Lake, Foy Lake, Morrison Lake, and Reservoir Lake. The lakes show synchroneity in timing of shifts in diatom community structure, but the nature of these changes differs among the lakes. Two of the sites provide highly resolved records of hydrologic balance, while the other two stratigraphic sequences primarily record temperature impact on lake thermal structure. All four lakes show significant change in five discrete intervals: 2200–2100, 1700–1600, 1350–1200, 800–600, and 250 cal yr BP. The similarities in the timing of change suggest overlying regional climatic influences on lake dynamics. The 800–600 cal yr BP shift is evident in other paleorecords throughout the Great Plains and western US, associated with the transition from the Medieval Climate Anomaly to the Little Ice Age. Large-scale climatic mechanisms that influence these lake environments may result from atmospheric circulation patterns that are driven by interactions between Pacific and Atlantic sea-surface temperatures, which are then locally modified by topography.

Description: Publication year: 2012 Source: Quaternary Research Anwar Alizai, Stephen Hillier, Peter D. Clift, Liviu Giosan, Andrew Hurst, Sam VanLaningham, Mark Macklin We employed X-ray diffraction methods to quantify clay mineral assemblages in the Indus Delta and flood plains since ~ 14 ka, spanning a period of strong climatic change. Assemblages are dominated by smectite and illite, with minor chlorite and kaolinite. Delta sediments integrate clays from across the basin and show increasing smectite input between 13 and 7.5 ka, indicating stronger chemical weathering as the summer monsoon intensified. Changes in clay mineralogy postdate changes in climate by 5–3 ka, reflecting the time needed for new clay minerals to form and be transported to the delta. Samples from the flood plains in Punjab show evidence for increased chemical weathering towards the top of the sections (6–〈 4 ka), counter to the trend in the delta, at a time of monsoon weakening. Clay mineral assemblages within sandy flood-plain sediment have higher smectite/(illite + chlorite) values than interbedded mudstones, suggestive of either stronger weathering or more sediment reworking since the Mid Holocene. We show that marine records are not always good proxies for weathering across the entire flood plain. Nonetheless, the delta record likely represents the most reliable record of basin-wide weathering response to climate change.

Description: Publication year: 2012 Source: Quaternary Research Mathieu Duval, Christophe Falguères, Jean-Jacques Bahain, Rainer Grün, Qingfeng Shao, Maxime Aubert, Jean-Michel Dolo, Jordi Agustí, Bienvenido Martínez-Navarro, Paul Palmqvist, Isidro Toro-Moyano The combined U-series/electron spin resonance (ESR) dating method was applied to nine teeth from two Early Pleistocene archaeological sites located in the Orce area (Guadix-Baza Basin, Southern Spain): Fuente Nueva-3 (FN-3) and Barranco León (BL). The combination of biostratigraphy and magnetostratigraphy places both sites between the Olduvai and Jaramillo subchrons (1.78–1.07 Ma). Our results highlight the difficulty of dating such old sites and point out the limits of the combined U-series/ESR dating method based on the US model. We identified several sources of uncertainties that may lead to inaccurate age estimates. Seven samples could not be dated because the dental tissues had ( 230 Th/ 234 U) activity ratios higher than equilibrium, indicating that uranium had probably leached from these tissues. It was however possible to calculate numerical estimates for two of the teeth, both from FN-3. One yielded a Middle Pleistocene age that seems to be strongly underestimated; the other provided an age of 1.19 ± 0.21 Ma, in agreement with data obtained from independent methods. The latter result gives encouragement that there are samples that can be used for routine dating of old sites.

Description: Publication year: 2012 Source: Quaternary Research Marcelo Accioly Teixeira de Oliveira, Jorge Luis Porsani, Gisele Leite de Lima, Vivian Jeske-Pieruschka, Hermann Behling Paleoenvironmental interpretation of proxy data derived from peatlands is largely based upon an evolutionary model for ombrotrophic bogs, in which peat accumulates in still environments. Reports on proxies obtained from minerotrophic fens, where hydrologic inputs are variable, are less common. In this study, a highland peatland in southern Brazil is presented through ground penetrating radar (GPR) and sedimentological, palynological and geochronologic data. The radar stratigraphic interpretation suggests a relatively complex history of erosion and deposition at the site since the beginning of Marine Isotope Stage 3 (MIS 3) interstadial period. In spite of this, radar stratigraphic and palynologic interpretations converge. Electromagnetic reflections tend to group in clusters that show lateral coherence and correlate with different sediment types, while pollen grains abound and are well preserved. As a result, the study of minerotrophic fens provides a source of proxies, suggesting that ombrotrophic bogs are not the only reliable source of data in wetlands for palynological analysis.

Description: Publication year: 2012 Source: Quaternary Research Joyce Lundberg, Donald A. McFarlane A distinctive white sediment in the caves of Mulu, Sarawak, Borneo is a well-preserved tephra, representing a fluvially transported surface air-fall deposit, re-deposited inside the caves. We show that the tephra is not the Younger Toba Tephra, formerly considered as most likely. The shards are rod-shaped with elongate tubular vesicles; the largest grains ~ 170 μm in length; of rhyolitic composition; and 87 Sr/ 86 Sr ratio of 0.70426 ± 0.00001. U–Th dating of associated calcites suggest that the tephra was deposited before 125 ± 4 ka, and probably before 156 ± 2 ka. Grain size and distance from closest potential source suggests an eruption of VEI 7. Prevailing winds, grain size, thickness of deposit, location of potential sources, and Sr isotopic ratio limit the source to the Philippines. Comparisons with the literature give the best match geochemically with layer 1822 from Ku et al. (2009a), dated by ocean core stratigraphy to 189 ka. This tephra represents a rare terrestrial repository indicating a very substantial Plinian/Ultra-Plinian eruption that covered the Mulu region of Borneo with ash, a region that rarely receives tephra from even the largest known eruptions in the vicinity. It likely will be a valuable chronostratigraphic marker for sedimentary, palaeontological and archaeological studies.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Pierre Sabatier, Laurent Dezileau, Christophe Colin, Louis Briqueu, Frédéric Bouchette, Philippe Martinez, Giuseppe Siani, Olivier Raynal, Ulrich Von Grafenstein A high-resolution record of paleostorm events along the French Mediterranean coast over the past 7000 years was established from a lagoonal sediment core in the Gulf of Lions. Integrating grain size, faunal analysis, clay mineralogy and geochemistry data with a chronology derived from radiocarbon dating, we recorded seven periods of increased storm activity at 6300–6100, 5650–5400, 4400–4050, 3650–3200, 2800–2600, 1950–1400 and 400–50 cal yr BP (in the Little Ice Age). In contrast, our results show that the Medieval Climate Anomaly (1150–650 cal yr BP) was characterised by low storm activity. The evidence for high storm activity in the NW Mediterranean Sea is in agreement with the changes in coastal hydrodynamics observed over the Eastern North Atlantic and seems to correspond to Holocene cooling in the North Atlantic. Periods of low SSTs there may have led to a stronger meridional temperature gradient and a southward migration of the westerlies. We hypothesise that the increase in storm activity during Holocene cold events over the North Atlantic and Mediterranean regions was probably due to an increase in the thermal gradient that led to an enhanced lower tropospheric baroclinicity over a large Central Atlantic–European domain.

Description: Publication year: 2012 Source: Quaternary Research Joan Bunbury, Konrad Gajewski Lake sediments from four sites in the southwest Yukon Territory, Canada, provided paleotemperature records for the past 2000 yr. An alpine and a forest site from the southeastern portion of the study area, near Kluane Lake, and another alpine-forest pair of lakes from the Donjek River area located to the northwest yielded chironomid records that were used to provide quantitative estimates of mean July air temperature. Prior to AD 800, the southwest Yukon was relatively cool whereas after AD 800 temperatures were more variable, with warmer conditions between ~ AD 1100 and 1400, cooler conditions during the Little Ice Age (~ AD 1400 to 1850), and warming thereafter. These records compare well with other paleoclimate evidence from the region.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Manuel Calvo-Rathert, Ángel Carrancho, Florian Stark, Juan José Villalaín, Mimi Hill This study tests if burnt soils and sediments can provide reliable records of geomagnetic field strength at the time of burning by carrying out an experiment to reproduce the prehistoric use of fire on a clayish soil substratum. Rock magnetic experiments showed that in the upper 0–1 cm of the central part of the burnt surface, remanence is a thermoremanent magnetization carried by single-domain magnetite and that samples are thermally stable. Fourteen specimens from that area were subjected to paleointensity experiments with the Coe method (1967). An intensity of 42.9 ± 5.7 μT was estimated below 440°C, whereas at higher temperatures magneto-mineralogical alterations were observed. Corresponding successful microwave intensity determinations from two specimens gave a mean value of 47.6 μT. Both results are in reasonable agreement with the expected field value of 45.2 μT. Burnt soils of archeological fires thus have the potential to record accurately the paleofield strength and may be useful targets for archeointensity investigations. Coincident results obtained from two different paleointensity determination methods support this conclusion.

Description: Publication year: 2012 Source: Quaternary Research Anna Coppola, Giovanni Leonelli, Maria Cristina Salvatore, Manuela Pelfini, Carlo Baroni Tree rings from temperature-limited environments are highly sensitive climate proxies, widely used to reconstruct past climate parameters for periods prior to the availability of instrumental data and to analyse the effect of recent global warming on tree growth. An analysis of the climatic signal in five high-elevation tree-ring width chronologies of European larch ( Larix decidua Mill.) from the tops of five different glacial valleys in the Italian Central Alps revealed that they contain a strong summer-temperature signal and that tree-ring growth is especially influenced by June temperatures. However, a moving correlation function analysis revealed a recent loss of the June temperature signal in the tree-ring chronologies. This signal reduction primarily involves the two lowest-altitude chronologies. It is probable that the observed increasing importance of late-summer temperature for tree-ring growth over the past 50 yr is an effect of the lengthening growing season and of the variations in the climate/tree-ring relationship over time. All the chronologies considered, especially those at the highest altitudes, show an increasing negative influence of June precipitation on tree-ring growth. The climatic signal recorded in tree-ring chronologies from the Italian Central Alps varies over time and is also differentially influenced by climatic parameters according to site elevation.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Gonzalo Jiménez-Moreno, R. Scott Anderson High-resolution pollen and magnetic susceptibility (MS) analyses have been carried out on a sediment core taken from a high-elevation alpine bog area located in Sierra Nevada, southern Spain. The earliest part of the record, from 8200 to about 7000 cal yr BP, is characterized by the highest abundance of arboreal pollen and Pediastrum , indicating the warmest and wettest conditions in the area at that time. The pollen record shows a progressive aridification since 7000 cal yr BP that occurred in two steps, first shown by a decrease in Pinus , replaced by Poaceae from 7000 to 4600 cal yr BP and then by Cyperaceae, Artemisia and Amaranthaceae from 4600 to 1200 cal yr BP. Pediastrum also decreased progressively and totally disappeared at ca. 3000 yr ago. The progressive aridification is punctuated by periodically enhanced drought at ca. 6500, 5200 and 4000 cal yr BP that coincide in timing and duration with well-known dry events in the Mediterranean and other areas. Since 1200 cal yr BP, several changes are observed in the vegetation that probably indicate the high-impact of humans in the Sierra Nevada, with pasturing leading to nutrient enrichment and eutrophication of the bog, Pinus reforestation and Olea cultivation at lower elevations.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Justine Kemp, Lynda C. Radke, Jon Olley, Steve Juggins, Patrick De Deckker Palaeosalinity records for groundwater-influenced lakes in the southwest Murray Basin were constructed from an ostracod-based, weighted-averaging transfer function, supplemented with evidence from Campylodiscus clypeus (diatom), charophyte oogonia, Coxiella striata (gastropod), Elphidium sp. (foraminifera), Daphniopsis sp. ephippia (Cladocera), and brine shrimp ( Parartemia zietziana ) faecal pellets, the δ 18 O of ostracods, and 〉 130 μm quartz sand counts. The chronology is based on optically stimulated luminescence and calibrated radiocarbon ages. Relatively wet conditions are marked by lower salinities between 9600 yr and 5700 yr ago, but mutually exclusive high- and low-salinity ostracod communities suggest substantial variability in effective precipitation in the early Holocene. A drier climate was firmly in place by 4500 yr and is marked at the groundwater-dominated NW Jacka Lake by an increase in aeolian quartz and, at Jacka Lake, by a switch from surface-water to groundwater dominance. Short-lived, low-salinity events at 8800, 7200, 5900, 4800, 2400, 1300 and 400 yr are similar in timing and number to those recorded on Australia's southern continental shelf, and globally, and provide evidence for the existence of the ~ 1500-yr cycle in mainland southern Australia. We surmise that these are cool events associated with periodic equatorward shifts in the westerly wind circulation.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Sarah J. Ivory, Anne-Marie Lézine, Annie Vincens, Andrew S. Cohen Fossil pollen analyses from northern Lake Malawi, southeast Africa, provide a high-resolution record of vegetation change during the Pleistocene/Holocene transition (~ 18–9 ka). Recent studies of local vegetation from lowland sites have reported contrasting rainfall signals during the Younger Dryas (YD). The Lake Malawi record tracks regional vegetation changes and allows comparison with other tropical African records identifying vegetation opening and local forest maintenance during the YD. Our record shows a gradual decline of afromontane vegetation at 18 ka. Around 14.5 ka, tropical seasonal forest and Zambezian miombo woodland became established. At ~ 13 ka, drier, more open formations gradually became prevalent. Although tropical seasonal forest taxa were still present in the watershed during the YD, this drought-intolerant forest type was likely restricted to areas of favorable edaphic conditions along permanent waterways. The establishment of drought-tolerant vegetation followed the reinforcement of southeasterly tradewinds resulting in a more pronounced dry winter season after ~ 11.8 ka. The onset of the driest, most open vegetation type was coincident with a lake low stand at the beginning of the Holocene. This study demonstrates the importance of global climate forcing and local geomorphological conditions in controlling vegetation distribution.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Guanghui Dong, Xin Jia, Chengbang An, Fahu Chen, Yan Zhao, Shichen Tao, Minmin Ma We studied the mid-Holocene climate change in eastern Qinghai Province, China and its impact on the evolution of Majiayao (3980–2050 BC) and Qijia (2183–1635 BC) cultures, near the important Neolithic site of Changning. The investigation focused on analyses of grain size, magnetic susceptibility, ratios of elemental contents, and pollen assemblage from a loess–paleosol sequence. The results indicate that the climate was wet during 5830–4900 cal yr BP, which promoted the development of early-mid Majiayao culture in eastern Qinghai Province. However, 4900–4700 cal yr BP were drought years in the region, responsible for the decline and eastward movement of prehistoric culture during the period of transition from early-mid to late Majiayao culture. The climate turned wet again during 4700–3940 cal yr BP, which accelerated the spread of Qijia culture to the middle reaches of the Huangshui River, including the Changning site.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Christy E. Briles, Cathy Whitlock, David J. Meltzer The last glacial-interglacial transition (LGIT; 19–9 ka) was characterized by rapid climate changes and significant ecosystem reorganizations worldwide. In western Colorado, one of the coldest locations in the continental US today, mountain environments during the late-glacial period are poorly known. Yet, archaeological evidence from the Mountaineer site (2625 m elev.) indicates that Folsom-age Paleoindians were over-wintering in the Gunnison Basin during the Younger Dryas Chronozone (YDC; 12.9–11.7 ka). To determine the vegetation and fire history during the LGIT, and possible explanations for occupation during a period thought to be harsher than today, a 17-ka-old sediment core from Lily Pond (3208 m elev.) was analyzed for pollen and charcoal and compared with other high-resolution records from the southern Rocky Mountains. Widespread tundra and Picea parkland and low fire activity in the cold wet late-glacial period transitioned to open subalpine forest and increased fire activity in the Bølling – Allerød period as conditions became warmer and drier. During the YDC, greater winter snowpack than today and prolonged wet springs likely expanded subalpine forest to lower elevations than today, providing construction material and fuel for the early inhabitants. In the early to middle Holocene, arid conditions resulted in xerophytic vegetation and frequent fire.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Stephen A. Hall, William L. Penner, Manuel R. Palacios-Fest, Artie L. Metcalf, Susan J. Smith A thick alluvial sequence in central New Mexico contains the Scholle wet meadow deposit that traces upstream to a paleospring. The wet meadow sediments contain an abundant fauna of twenty-one species of freshwater and terrestrial mollusks and ten species of ostracodes. The mollusks and ostracodes are indicative of a local high alluvial water table with spring-supported perennial flow but without standing water. Pollen analysis documents shrub grassland vegetation with sedges, willow, and alder in a riparian community. Stable carbon isotopes from the wet meadow sediments have δ 13 C values ranging from − 22.8 to − 23.3‰, indicating that 80% of the organic carbon in the sediment is derived from C 3 species. The wet meadow deposit is AMS dated 10,400 to 9700 14 C yr BP, corresponding to 12,300 to 11,100 cal yr BP and overlapping in time with the Younger Dryas event (YD). The wet meadow became active about 500 yr after the beginning of the YD and persisted 400 yr after the YD ended. The Scholle wet meadow is the only record of perennial flow and high water table conditions in the Abo Arroyo drainage basin during the past 13 ka.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Gabriel Magnan, Martin Lavoie, Serge Payette A 7000-year record of local fire history was reconstructed from three ombrotrophic peatlands in the James Bay lowlands (northwestern Québec, Canada) using a high-resolution analysis of macroscopic charcoal (long axis ≥ 0.5 mm). The impact of fire on vegetation changes was evaluated using detailed analysis of plant macrofossils. Compared to upland boreal forest, fire incidence in these Sphagnum -dominated bogs is rather low. Past fire occurrence seems to have been controlled primarily by internal processes associated with local hydroseral succession. Size of the peatland basin and distance from the well-drained forest soils also appear to be factors controlling fire occurrence. The impact of peatland fires on long-term vegetation succession appears negligible except in a forested bog, where it initiated the replacement of Sphagnum by mosses. In some circumstances, fire caused marked changes in the bryophyte assemblages over many decades. However, ombrotrophic peatland vegetation is generally resilient to surface fire.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Mónika Tóth, Enikő K. Magyari, Stephen J. Brooks, Mihály Braun, Krisztina Buczkó, Miklós Bálint, Oliver Heiri Late glacial and early Holocene summer temperatures were reconstructed based on fossil chironomid assemblages at Lake Brazi (Retezat Mountains) with a joint Norwegian–Swiss transfer function, providing an important addition to the late glacial quantitative climate reconstructions from Europe. The pattern of the late glacial temperature changes in Lake Brazi show both similarities and some differences from the NGRIP δ 18 O record and other European chironomid-based reconstructions. Our reconstruction indicates that at Lake Brazi (1740 m a.s.l.) summer air temperature increased by ~ 2.8°C at the Oldest Dryas/Bølling transition (GS-2/GI-1) and reached 8.1–8.7°C during the late glacial interstade. The onset of the Younger Dryas (GS-1) was characterized by a weak (〈 1°C) decrease in chironomid-inferred temperatures. Similarly, at the GS-1/Holocene transition no major changes in summer temperature were recorded. In the early Holocene, summer temperature increased in two steps and reached ~ 12.0–13.3°C during the Preboreal. Two short-term cold events were detected during the early Holocene between 11,480–11,390 and 10,350–10,190 cal yr BP. The first cooling coincides with the Preboreal oscillation and shows a weak (0.7°C) temperature decrease, while the second is characterized by 1°C cooling. Both cold events coincide with cooling events in the Greenland ice core records and other European temperature reconstructions.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Alethéa E.M. Sallun, William Sallun Filho, Kenitiro Suguio, Marly Babinski, Simone M.C.L. Gioia, Benjamin A. Harlow, Wania Duleba, Paulo E. De Oliveira, Maria Judite Garcia, Cinthia Z. Weber, Sérgio R. Christofoletti, Camilla da S. Santos, Vanda B. de Medeiros, Juliana B. Silva, Maria Cristina Santiago-Hussein, Rosana S. Fernandes The paleoclimatic record of Juréia Paleolagoon, coastal southeastern Brazil, includes cyclic and gradual changes with different intensities and frequencies through geological time, and it is controlled by astronomical, geophysical, and geological phenomena. These variations are not due to one single cause, but they result from the interaction of several factors, which act at different temporal and spatial scales. Here, we describe paleoenvironmental evidence regarding climatic and sea level changes from the last 9400 cal yr BP at the Juréia Paleolagoon — one of the main groups of protected South Atlantic ecosystems. Geochemical evidences were used to identify anomalies from multi-proxy analyses of a paleolagoon sediment core. The anomalies of centennial scale were correlated to climate and transgression–regression cycles from the Holocene period. Decadal scale anomalous oscillations in the Quaternary paleolagoon sediments occur between 9400 and 7500 cal yr BP, correlated with long- and short-term natural events, which generated high sedimentation rates, mainly between 8385 and 8375 cal yr BP (10 cm/yr). Our results suggest that a modern-day short-duration North Atlantic climatic event, such as the 8.2 ka event, could affect the environmental equilibrium in South America and intensify the South American Summer Monsoon.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Barbara Hermanowski, Marcondes Lima da Costa, Hermann Behling New pollen, micro-charcoal, sediment and mineral analyses of a radiocarbon-dated sediment core from the Serra Sul dos Carajás (southeast Amazonia) indicate changes between drier and wetter climatic conditions during the past 25,000 yr, reflected by fire events, expansion of savanna vegetation and no-analog Amazonian forest communities. A cool and dry last glacial maximum (LGM) and late glacial were followed by a wet phase in the early Holocene lasting for ca. 1200 yr, when tropical forest occurred under stable humid conditions. Subsequently, an increasingly warm, seasonal climate established. The onset of seasonality falls within the early Holocene warm period, with possibly longer dry seasons from 10,200 to 3400 cal yr BP, and an explicitly drier phase from 9000 to 3700 cal yr BP. Modern conditions with shorter dry seasons became established after 3400 cal yr BP. Taken together with paleoenvironmental evidence from elsewhere in the Amazon Basin, the observed changes in late Pleistocene and Holocene vegetation in the Serra Sul dos Carajás likely reflect large-scale shifts in precipitation patterns driven by the latitudinal displacement of the Inter-Tropical Convergence Zone and changes in sea-surface temperatures in the tropical Atlantic.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Donald T. Rodbell, Holli M. Frey, Matthew R.F. Manon, Jacqueline A. Smith, Nicholas A. McTurk Mylonite textures in granodiorite boulders are responsible for higher rates of surface denudation of host rocks and the progressive development of unusual rock weathering features, termed weathering posts . These textures are characterized by smaller grain sizes, higher biotite content, and a higher biotite axial ratio in host rocks relative to weathering posts. Elemental concentrations do not show a significant difference between weathering posts and the host rocks in which they are found, and this reflects the absence of a weathering residue on the rock surfaces. Chemical weathering loosens the bonds between mineral grains through the expansion of biotite, and the loosened grains fall off or are blown off the boulder surface and continue their chemical alteration in the surrounding soil. The height of weathering posts on late Quaternary moraines increases at a linear rate of ~ 1.45 ± 0.45 cm (1000 yr) − 1 until post heights reach the diameter of host rocks. Such a rate of boulder denudation, if unrecognized, would generate significant errors (〉 20%) in cosmogenic exposure ages for Pleistocene moraines. Given the paucity of boulders with diameters that significantly exceed 1.5 m, the maximum age of utility of weathering posts as a numeric age indicator is ~ 100 ka.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Shailesh Agrawal, Prasanta Sanyal, Anindya Sarkar, Manoj Kumar Jaiswal, Koushik Dutta Oxygen and carbon isotope ratios of soil carbonate and carbon isotope ratios of soil organic matter (SOM) separated from three cores, Kalpi, IITK and Firozpur, of the Ganga Plain, India are used to reconstruct past rainfall variations and their effect on ambient vegetation. The δ 18 O values of soil carbonate (δ 18 O SC ) analyzed from the cores range from − 8.2 to − 4.1‰. Using these variations in δ 18 O SC values we are able, for the first time, to show periodic change in rainfall amount between 100 and 18 ka with three peaks of higher monsoon at about 100, 40 and 25 ka. The estimation of rainfall variations using δ 18 O value of rainwater-amount effect suggests maximum decrease in rainfall intensity (~ 20%) during the last glacial maximum. The δ 13 C values of soil carbonate (δ 13 C SC ) and SOM (δ 13 C SOM ) range from − 6.3 to + 1.6‰ and − 28.9 to − 19.4‰, respectively, implying varying proportions of C 3 and C 4 vegetations over the Ganga Plain during the last 100 ka. The comparison between monsoonal rainfall and atmospheric CO 2 with vegetation for the time period 84 to 18 ka indicate that relative abundances of C 3 and C 4 vegetations were mainly driven by variations in monsoonal rainfall.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Charline Giguet-Covex, Fabien Arnaud, Dirk Enters, Jérôme Poulenard, Laurent Millet, Pierre Francus, Fernand David, Pierre-Jérôme Rey, Bruno Wilhelm, Jean-Jacques Delannoy In central Western Europe, several studies have shown that colder Holocene periods, such as the Little Ice Age, also correspond to wet periods. However, in mountain areas which are highly sensitive to erosion processes and where precipitation events can be localized, past evolution of hydrological activity might be more complicated. To assess these past hydrological changes, a paleolimnological approach was applied on a 13.4-m-long sediment core taken in alpine Lake Anterne (2063 m asl) and representing the last 3.5 ka. Lake sedimentation is mainly composed of flood deposits triggered by precipitation events. Sedimentological and geochemical analyses show that floods were more frequent during cold periods while high-intensity flood events occurred preferentially during warmer periods. In mild temperature conditions, both flood patterns are present. This underlines the complex relationship between flood hazards and climatic change in mountain areas. During the warmer and/or dryer times of the end of Iron Age and the Roman Period, both the frequency and intensity of floods increased. This is interpreted as an effect of human-induced clearing for grazing activities and reveals that anthropogenic interferences must be taken into account when reconstructing climatic signals from natural archives.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Antonio B. Rodriguez, Matthew N. Waters, Michael F. Piehler Carolina bays are nearly ubiquitous along ~ 1300 km of the North American Atlantic Coastal Plain, but relatively few bays have been examined in detail, making their formation and evolution a topic of controversy. The Lake Mattamuskeet basin, eastern North Carolina, USA, is a conglomeration of multiple Carolina bays that form a 〉 162 km 2 lake. The eastern shoreline of the lake is made up of a 2.9-km-wide plain of parabolic ridges that recorded rapid shoreface progradation. The lower shoreface deposit contains abundant charcoal beds and laminae dated 6465–6863 cal yr BP, corresponding with initiation of a lacustrine environment in the eastern part of the lake. A core from the western part of the lake sampled a 1541–1633 cal yr BP charcoal bed at the base of the lacustrine unit, indicating formation of this part of the basin postdates the eastern basin. Lake Mattamuskeet has no relationship to the Younger Dryas or a linked impact event because rim accretion significantly postdates 12,000 cal yr BP. The shoreline progradation, and association of charcoal beds with the oldest lake sediment in both main parts of the basin, suggest that fire and subsequent hydrodynamic processes were associated with initial formation of these Carolina bays.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Bruno Malaizé, Elsa Jullien, Amandine Tisserand, Charlotte Skonieczny, E. Francis Grousset, Frédérique Eynaud, Catherine Kissel, Jérôme Bonnin, Svenja Karstens, Philippe Martinez, Aloys Bory, Vivianne Bout-Roumazeilles, Thibaut Caley, Xavier Crosta, Karine Charlier, Linda Rossignol, José-Abel Flores, Ralph Schneider A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~ 1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0–0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ 18 O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass δ 13 C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ 13 C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ 13 C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ 18 O and δ 13 C values of deep waters.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Charlotte G. Cook, Melanie J. Leng, Richard T. Jones, Peter G. Langdon, Enlou Zhang A detailed understanding of long-term climatic and environmental change in southwestern China is hampered by a lack of long-term regional palaeorecords. Organic analysis (%TOC, %TN, C/N ratios and δ 13 C values) of a sediment sequence from Lake Shudu, Yunnan Province (ca. 22.6–10.5 cal ka BP) indicates generally low aquatic palaeoproductivity rates over millennial timescales in response to cold, dry climatic conditions. However, the record is punctuated by two marked phases of increased aquatic productivity from ca. 17.7 to 17.1 cal ka BP and from ca. 11.9 to 10.5 cal ka BP. We hypothesise that these shifts reflect a marked, stepwise lacustrine response to Asian summer monsoon strengthening during the last deglaciation.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Damien Rius, Boris Vannière, Didier Galop Located on a mountain pass in the west-central Pyrenees, the Col d'Ech peat bog provides a Holocene fire and vegetation record based upon nine 14 C (AMS) dates. We aim to compare climate-driven versus human-driven fire regimes in terms of frequency, fire episodes distribution, and impact on vegetation. Our results show the mid-Holocene (8500–5500 cal yr BP) to be characterized by high fire frequency linked with drier and warmer conditions. However, fire occurrences appear to have been rather stochastic as underlined by a scattered chronological distribution. Wetter and colder conditions at the mid-to-late Holocene transition (4000–3000 cal yr BP) led to a decrease in fire frequency, probably driven by both climate and a subsequent reduction in human land use. On the contrary, from 3000 cal yr BP, fire frequency seems to be driven by agro-pastoral activities with a very regular distribution of events. During this period fire was used as a prominent agent of landscape management.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 P. Sargent Bray, Claudia M. Jones, Stewart J. Fallon, Jochen J. Brocks, Simon C. George Assigning accurate dates to hypersaline sediments opens important terrestrial records of local and regional paleoecologies and paleoclimatology. However, as of yet no conventional method of dating hypersaline systems has been widely adopted. Biomarker, mineralogical, and radiocarbon analyses of sediments and organic extracts from a shallow (13 cm) core from a hypersaline playa, Lake Tyrrell, southeastern Australia, produce a coherent age-depth curve beginning with modern microbial mats and extending to ~ 7500 cal yr BP. These analyses are furthermore used to identify and constrain the timing of the most recent change in hydrological regime at Lake Tyrrell, a shift from a clay deposit to the precipitation of evaporitic sands occurring at some time between ~ 4500 and 7000 yr. These analyses show the potential for widespread dating of hypersaline systems integrating the biomarker approach, reinforce the value of the radiocarbon content of biomarkers in understanding the flow of carbon in modern ecologies, and validate the temporal dimension of data provided by biomarkers when dating late Quaternary sediments.

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Kristian Vasskog, Øyvind Paasche, Atle Nesje, John F. Boyle, H.J.B. Birks We explore the possibility of building a continuous glacier reconstruction by analyzing the integrated sedimentary response of a large (440 km 2 ) glacierized catchment in western Norway, as recorded in the downstream lake Nerfloen (N61°56’, E6°52’). A multi-proxy numerical analysis demonstrates that it is possible to distinguish a glacier component in the ~ 8000-yr-long record, based on distinct changes in grain size, geochemistry, and magnetic composition. Principal Component Analysis (PCA) reveals a strong common signal in the 15 investigated sedimentary parameters, with the first principal component explaining 77% of the total variability. This signal is interpreted to reflect glacier activity in the upstream catchment, an interpretation that is independently tested through a mineral magnetic provenance analysis of catchment samples. Minimum glacier input is indicated between 6700–5700 cal yr BP, probably reflecting a situation when most glaciers in the catchment had melted away, whereas the highest glacier activity is observed around 600 and 200 cal yr BP. During the local Neoglacial interval (~ 4200 cal yr BP until present), five individual periods of significantly reduced glacier extent are identified at ~ 3400, 3000–2700, 2100–2000, 1700–1500, and ~ 900 cal yr BP.

Description: Author(s): Gertjan Koster, Lior Klein, Wolter Siemons, Guus Rijnders, J. Steven Dodge, Chang-Beom Eom, Dave H. A. Blank, and Malcolm R. Beasley The complex oxide perovskite SrRuO 3 is recognized as an almost ideal material for study: it can be grown epitaxially on a variety of complex oxide substrates, it is a good conductor without the need for added dopants, and it is a model system for the study of itinerant ferromagnetism with intermedia... [Rev. Mod. Phys. 84, 253] Published Thu Mar 08, 2012

Description: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 1 Torben C. Rick, Gregory A. Henkes, Darrin L. Lowery, Steven M. Colman, Brendan J. Culleton Radiocarbon dates from known age, pre-bomb eastern oyster ( Crassostrea virginica ) shells provide local marine reservoir corrections (∆ R ) for Chesapeake Bay and the Middle Atlantic coastal area of eastern North America. These data suggest subregional variability in ∆ R , ranging from 148 ± 46 14 C yr on the Potomac River to − 109 ± 38 14 C yr at Swan Point, Maryland. The ∆ R weighted mean for the Chesapeake's Western Shore (129 ± 22 14 C yr) is substantially higher than the Eastern Shore (− 88 ± 23 14 C yr), with outer Atlantic Coast samples falling between these values (106 ± 46 and 2 ± 46 14 C yr). These differences may result from a combination of factors, including 14 C-depleted freshwater that enters the bay from some if its drainages, 14 C-depleted seawater that enters the bay at its mouth, and/or biological carbon recycling. We advocate using different subregional ∆ R corrections when calibrating 14 C dates on aquatic specimens from the Chesapeake Bay and coastal Middle Atlantic region of North America.

Description: Author(s): Xiaofeng Liu, Satoru Matsuishi, Satoru Fujitsu, and Hideo Hosono MgFeGe with a CeFeSi-type structure was synthesized by high-pressure method, and its electrical transport, magnetic properties, and electronic structure were investigated. It is found that MgFeGe has the smallest c / a (1.65) ratio and the shortest in-plane Fe-Fe distance (2.75 Å) among CeFeSi-type an... [Phys. Rev. B 85, 104403] Published Thu Mar 08, 2012

Description: Author(s): Tobias Marten, Björn Alling, Eyvaz I. Isaev, Hans Lind, Ferenc Tasnádi, Lars Hultman, and Igor A. Abrikosov The structure of the SiN x tissue phase in superhard TiN/SiN x nanocomposites has been debated in the literature. We present a theoretical investigation of the possibility of crystalline and coherent (001) interfaces that satisfies the two necessary criteria, stability with respect to lattice vibratio... [Phys. Rev. B 85, 104106] Published Thu Mar 08, 2012

Description: Author(s): I. L. Aleiner, B. L. Altshuler, and Y. G. Rubo In spite of having finite lifetimes exciton-polaritons in microcavities are known to condense at strong enough pumping of the reservoir. We present an analytical theory of such Bose condensates on a set of localized one-particle states: condensation centers. To understand the physics of these arrays... [Phys. Rev. B 85, 121301] Published Thu Mar 08, 2012

Description: Author(s): Eric Cockayne The structure of finite-area topological defects in graphene is described in terms of both the direct honeycomb lattice and its dual triangular lattice. Such defects are equivalent to cutting out a patch of graphene and replacing it with a different patch with the same number of dangling bonds. An i... [Phys. Rev. B 85, 125409] Published Thu Mar 08, 2012

Description: Author(s): Jianmin Dong, Wei Zuo, Jianzhong Gu, and Umberto Lombardo We establish a correlation for the symmetry energy at saturation density S 0 , slope parameter L , and curvature parameter K sym based on widely different mean-field interactions. With the help of this correlation and available empirical and theoretical information, the density-dependent behavior around... [Phys. Rev. C 85, 034308] Published Thu Mar 08, 2012

Description: Author(s): Nan Zhao, Sai-Wah Ho, and Ren-Bao Liu We theoretically study the decoherence and the dynamical decoupling control of nitrogen vacancy center electron spins in high-purity diamond, where the hyperfine interaction with 13 C nuclear spins is the dominating decoherence mechanism. The decoherence is formulated as the entanglement between the ... [Phys. Rev. B 85, 115303] Published Thu Mar 08, 2012

Description: Author(s): Hiroshi de Sandes and Rogerio Rosenfeld The radion, a scalar particle associated with the radius of a compact warped extra dimension, may be the lightest new particle in this class of models. Its couplings to SM particles are proportional to the their masses, similar to the usual Higgs boson, but suppressed by a scale Λ r , the radion vacuu... [Phys. Rev. D 85, 053003] Published Thu Mar 08, 2012

Description: Author(s): A. G. Galstyan, O. Chuluunbaatar, Yu. V. Popov, and B. Piraux We study the effects of nonzero photon momentum on the triply differential cross section (TDCS) for ( γ ,2 e ) processes. Due to the low value of the photon momentum, these effects are weak and manifest only in special kinematical conditions such as the back-to-back emission of the electrons with equal ... [Phys. Rev. A 85, 023418] Published Tue Feb 21, 2012

Description: Author(s): I. Blank, S. Otranto, C. Meinema, R. E. Olson, and R. Hoekstra Single electron transfer and ionization in collisions of N 5+ and Ne 8+ with ground state Na( 3 s ) and laser excited Na * ( 3 p ) are investigated both experimentally and theoretically at collision energies from 1 to 10 keV/amu, which includes the classical orbital velocity of the valence electron. State-sel... [Phys. Rev. A 85, 022712] Published Tue Feb 21, 2012

Description: Author(s): Markus Falkenau, Valentin V. Volchkov, Jahn Rührig, Hannes Gorniaczyk, and Axel Griesmaier Recently, we have experimentally demonstrated a continuous loading mechanism for an optical dipole trap from a guided atomic beam [ M. Falkenau, V. V. Volchkov, J. Rührig, A. Griesmaier and T. Pfau Phys. Rev. Lett. 106 163002 (2011) ]. The observed evolution of the number of atoms and temperature in... [Phys. Rev. A 85, 023412] Published Tue Feb 21, 2012

Description: Author(s): B. Gaire, J. McKenna, M. Zohrabi, K. D. Carnes, B. D. Esry, and I. Ben-Itzhak The dissociation of D 3 + in intense ultrashort laser pulses is investigated using an improved coincidence three-dimensional momentum imaging method that allows clear separation of all fragmentation channels and the determination of the kinetic energy release down to zero. Our results, using 10-fs, 79... [Phys. Rev. A 85, 023419] Published Tue Feb 21, 2012

Description: Author(s): So Takei, Chien-Hung Lin, Brandon M. Anderson, and Victor Galitski We study interacting Rashba-Dresselhaus fermions in two spatial dimensions. First, we present an exact solution to the two-particle bound-state problem of spin-orbit (SO)-coupled fermions for arbitrary Rashba and Dresselhaus SO interactions. An exact molecular-wave function and the Green's function ... [Phys. Rev. A 85, 023626] Published Tue Feb 21, 2012

Description: Author(s): Jianhua Zeng and Boris A. Malomed It has recently been discovered that stabilization of two-dimensional (2D) solitons against the critical collapse in media with cubic nonlinearity by means of nonlinear lattices (NLs) is a challenging problem. We address the one-dimensional (1D) version of the problem, i.e., the nonlinear-Schrödinge... [Phys. Rev. A 85, 023824] Published Tue Feb 21, 2012

Description: Author(s): Yi Yin, H. Wang, M. Mariantoni, Radoslaw C. Bialczak, R. Barends, Y. Chen, M. Lenander, Erik Lucero, M. Neeley, A. D. O'Connell, D. Sank, M. Weides, J. Wenner, T. Yamamoto, J. Zhao, A. N. Cleland, and John M. Martinis A superconducting qubit coupled to a microwave resonator provides a controllable system that enables fundamental studies of light-matter interactions. In the dispersive regime, photons in the resonator exhibit induced frequency and phase shifts which are revealed in the resonator transmission spectr... [Phys. Rev. A 85, 023826] Published Tue Feb 21, 2012