Early Postglacial Sedimentation of Lower Seymour Valley, Southwestern British Columbia

In lower Seymour Valley, much of the sediment derived from the erosion of valley-side drift (paraglacial sediments) remains in storage in the form of alluvial fans and aprons. Fluvial incision into these features has exposed sections for lithostratigraphic and chronological study. Radiocarbon dating of organic-rich beds within these deposits indicate that paraglacial sedimentation of lower Seymour Valley commenced before 11.4 ka, was periodic, and was essentially complete by about 9 ka; Seymour River had incised to its present vertical position by about 5 ka. Furthermore, our radiocarbon ages indicate that, although paraglacial sedimentation commenced shortly following deglaciation when the climate was cool and moist, a significant amount of sedimentation occurred during a transition from wet and moist climate to warm and dry (xerothermic) conditions (ca. 10 ka). Charcoal-rich beds indicate that some erosional events may have been a result of slope instability caused by fire.La plus grande partie des sédiments de la vallée résultant de l'érosion latérale des dépôts « paraglaciaires » demeurent accumulés sous forme de cône alluvial ou de plaine alluviale. L'encaissement fluviatile dans ces formes a mis au jour des coupes favorisant les études lithostratigraphiques et chronologiques. La datation au radiocarbone de lits riches en matière organique montre que la sédimentation « paraglaciaire » périodique a commencé avant 11,4 ka et s'est à toutes fins pratiques terminée vers 9 ka dans la vallée. L'encaissement de la Seymour River jusqu'à son niveau actuel était atteint vers 5 ka. De plus, les datations montrent que même si la sédimentation « paraglaciaire » a commencé peu après la déglaciation, alors que le climat était frais et humide, une bonne partie de la sédimentation s'est effectuée au cours d'une période de transition vers un climat chaud et sec (conditions xérothermiques) vers 10ka. Les lits riches en charbon indiquent qu'une certaine partie de l'érosion est attribuable à l'instabilité des pentes occasionnée par les feux

Catastrophic vs Gradual Collapse of Thin-Walled Nanocrystalline Ni Hollow Cylinders As Building Blocks of Microlattice Structures

Lightweight yet stiff and strong lattice structures are attractive for various engineering applications, such as cores of sandwich shells and components designed for impact mitigation. Recent breakthroughs in manufacturing enable efficient fabrication of hierarchically architected microlattices, with dimensional control spanning seven orders of magnitude in length scale. These materials have the potential to exploit desirable nanoscale-size effects in a macroscopic structure, as long as their mechanical behavior at each appropriate scale – nano, micro, and macro levels – is properly understood. In this letter, we report the nanomechanical response of individual microlattice members. We show that hollow nanocrystalline Ni cylinders differing only in wall thicknesses, 500 and 150 nm, exhibit strikingly different collapse modes: the 500 nm sample collapses in a brittle manner, via a single strain burst, while the 150 nm sample shows a gradual collapse, via a series of small and discrete strain bursts. Further, compressive strength in 150 nm sample is 99.2% lower than predicted by shell buckling theory, likely due to localized buckling and fracture events observed during in situ compression experiments. We attribute this difference to the size-induced transition in deformation behavior, unique to nanoscale, and discuss it in the framework of “size effects” in crystalline strength

Open Gromov-Witten Invariants of Toric Calabi-Yau 3-Folds

We present a proof of the mirror conjecture of Aganagic-Vafa [arXiv:hep-th/0012041] and Aganagic-Klemm-Vafa [arXiv:hep-th/0105045] on disk enumeration in toric Calabi-Yau 3-folds for all smooth semi-projective toric Calabi-Yau 3-folds. We consider both inner and outer branes, at arbitrary framing. In particular, we recover previous results on the conjecture for (i) an inner brane at zero framing in the total space of the canonical line bundle of the projective plane (Graber-Zaslow [arXiv:hep-th/0109075]), (ii) an outer brane at arbitrary framing in the resolved conifold (Zhou [arXiv:1001.0447]), and (iii) an outer brane at zero framing in the total space of the canonical line bundle of the projective plane (Brini [arXiv:1102.0281, Section 5.3]).Comment: 39 pages, 11 figure

Harper operators, Fermi curves, and Picard-Fuchs equations

This paper is a continuation of the work on the spectral problem of Harper operator using algebraic geometry. We continue to discuss the local monodromy of algebraic Fermi curves based on Picard-Lefschetz formula. The density of states over approximating components of Fermi curves satisfies a Picard-Fuchs equation. By the property of Landen transformation, the density of states has a Lambert series as the quarter period. A $q$-expansion of the energy level can be derived from a mirror map as in the B-model.Comment: v2, 13 pages, minor changes have been mad

Classical Scattering in 1+11+1 Dimensional String Theory

We find the general solution to Polchinski's classical scattering equations for $1+1$ dimensional string theory. This allows efficient computation of scattering amplitudes in the standard Liouville $\times$ $c=1$ background. Moreover, the solution leads to a mapping from a large class of time-dependent collective field theory backgrounds to corresponding nonlinear sigma models. Finally, we derive recursion relations between tachyon amplitudes. These may be summarized by an infinite set of nonlinear PDE's for the partition function in an arbitrary time-dependent background.Comment: 15 p

Driven Morse Oscillator: Model for Multi-photon Dissociation of Nitrogen Oxide

Within a one-dimensional semi-classical model with a Morse potential the possibility of infrared multi-photon dissociation of vibrationally excited nitrogen oxide was studied. The dissociation thresholds of typical driving forces and couplings were found to be similar, which indicates that the results were robust to variations of the potential and of the definition of dissociation rate. PACS: 42.50.Hz, 33.80.WzComment: old paper, 8 pages 6 eps file

Trace initial interaction from final state observable in relativistic heavy ion collisions

In order to trace the initial interaction in ultra-relativistic heavy ion collision in all azimuthal directions, two azimuthal multiplicity-correlation patterns -- neighboring and fixed-to-arbitrary angular-bin correlation patterns -- are suggested. From the simulation of Au + Au collisions at 200 GeV by using the Monte Carlo models RQMD with hadron re-scattering and AMPT with and without string melting, we observe that the correlation patterns change gradually from out-of-plane preferential one to in-plane preferential one when the centrality of collision shifts from central to peripheral, meanwhile the anisotropic collective flow v_2 keeps positive in all cases. This regularity is found to be model and collision energy independent. The physics behind the two opposite trends of correlation patterns, in particular, the presence of out-of-plane correlation patterns at RHIC energy, are discussed.Comment: 5pages, 4figure

Scale-invariant magnetoresistance in a cuprate superconductor

The anomalous metallic state in high-temperature superconducting cuprates is masked by the onset of superconductivity near a quantum critical point. Use of high magnetic fields to suppress superconductivity has enabled a detailed study of the ground state in these systems. Yet, the direct effect of strong magnetic fields on the metallic behavior at low temperatures is poorly understood, especially near critical doping, $x=0.19$. Here we report a high-field magnetoresistance study of thin films of \LSCO cuprates in close vicinity to critical doping, $0.161\leq x\leq0.190$. We find that the metallic state exposed by suppressing superconductivity is characterized by a magnetoresistance that is linear in magnetic field up to the highest measured fields of $80$T. The slope of the linear-in-field resistivity is temperature-independent at very high fields. It mirrors the magnitude and doping evolution of the linear-in-temperature resistivity that has been ascribed to Planckian dissipation near a quantum critical point. This establishes true scale-invariant conductivity as the signature of the strange metal state in the high-temperature superconducting cuprates.Comment: 10 pages, 3 figure

The operator algebra of the discrete state operators in 2D gravity with non-vanishing cosmological constant

Remarks are given to the structure of physical states in 2D gravity coupled to $C\leq 1$ matter. The operator algebra of the discrete state operators is calculated for the theory with non-vanishing cosmological constant.Comment: 17 page