101 research outputs found
A Chapter on the Shakers: Reprint
No full textReprinted from Farmer’s Monthly Visitor 11, no. 4 (April 30, 1849): 55-58.
In this unsigned article Isaac Hill describes a number of the Whitcher family members who lived at Canterbury, N.H., with particular attention to John Whitcher. Hill, as editor of the Farmer’s Monthly Visitor, wrote regularly about the Shakers in New Hampshire, always from a sympathetic viewpoint. He was certainly the author of this article. He also describes a visit by Henry Blinn’s sister. Hill cites the value of the education the Shakers provide for their children, names the individual children in the current class, and records autobiographical statements in verse by six children, age four to six
Classifications of elliptic fibrations of a singular K3 surface
No full textWe classify, up to automorphisms, the elliptic fibrations on the singular K3 whose transcendenatl lattice is isometric to +
Brain microstructure reveals early abnormalities more than two years prior to clinical progression from mild cognitive impairment to Alzheimer's disease.
No full textDiffusion imaging is a promising marker of microstructural damage in neurodegenerative disorders, but interpretation of its relationship with underlying neuropathology can be complex. Here, we examined both volumetric and brain microstructure abnormalities in 13 amnestic patients with mild cognitive impairment (MCI), who progressed to probable Alzheimer's disease (AD) no earlier than 2 years after baseline scanning, in order to focus on early, and hence more sensitive, imaging markers. We compared them to 22 stable amnestic MCI patients with similar cognitive performance and episodic memory impairment but who did not show progression of symptoms for at least 3 years. Significant group differences were mainly found in the volume and microstructure of the left hippocampus, while white matter group differences were also found in the body of the fornix, left fimbria, and superior longitudinal fasciculus (SLF). Diffusion index abnormalities in the SLF were the sign of a subtle microstructural injury not detected by standard atrophy measures in the corresponding gray matter regions. The microstructural measure obtained in the left hippocampus using diffusion imaging showed the most substantial differences between the two groups and was the best single predictor of future progression to AD. An optimal prediction model (91% accuracy, 85% sensitivity, 96% specificity) was obtained by combining MRI measures and CSF protein biomarkers. These results highlight the benefit of using the information of brain microstructural damage, in addition to traditional gray matter volume, to detect early, subtle abnormalities in MCI prior to clinical progression to probable AD and, in combination with CSF markers, to accurately predict such progression
Investigating the interaction of high-intensity XUV pulses from a free-electron laser with warm dense aluminium
No full textIn this Thesis I describe the ongoing investigations into the interaction of high- intensity XUV light with materials in extreme conditions. The focus will be on the series of experiments that took place using FLASH - the first XUV Free-Electron Laser and the attempts to create and probe Warm Dense Matter using Aluminium as the target metal. By focusing the 92eV FEL beam using a specially designed Off-Axis Parabolic mirror, we created the highest intensity XUV light ever produced. We then went on to induce transparency in thin AI films with the high-intensity pulses and using an XUV spectrometer we were able to obtain a great deal of information on the propertied and distribution of the electrons in the conduction band in this highly excited state. We also look at the optical properties of Warm Dense Aluminium for photons with energies below the L-edge and finally attempt to describe the evolution of the AI target when irradiated by a high-intensity XUV pulse using results gathered in this Thesis, theoretical models and computer simulations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Multivariate spectral analysis using Hilbert wavelet pairs
No full textWe investigate the use of Hilbert wavelet pairs (HWPs) in the non-decimated discrete wavelet transform for the time-varying spectral analysis of multivariate time series. HWPs consist of two high-pass and two low-pass compactly supported filters, such that one high-pass filter is the Hilbert transform (approximately) of the other. Thus, common quantities in the spectral analysis of time series (e.g., power spectrum, coherence, phase) may be estimated in both time and frequency. Compact support of the wavelet filters ensures that the frequency axis will be partitioned dyadically as with the usual discrete wavelet transform. The proposed methodology is used to analyze a bivariate time series of zonal (u) and meridional (v) winds over Truk Island
Zeta functions of monomial deformations of delsarte hypersurfaces
No full textLet Xλ and X′λ be monomial deformations of two Delsarte hypersurfaces in weighted projective spaces. In this paper we give a sufficient condition so that their zeta functions have a common factor. This generalises results by Doran, Kelly, Salerno, Sperber, Voight and Whitcher [arXiv:1612.09249], where they showed this for a particular monomial deformation of a Calabi-Yau invertible polynomial. It turns out that our factor can be of higher degree than the factor found in [arXiv:1612.09249].This paper is a contribution to the Special Issue on Modular Forms and String Theory in honor of Noriko
Yui. The full collection is available at http://www.emis.de/journals/SIGMA/modular-forms.html.
The author would like to thank John Voight and Tyler Kelly for various conversations on this
topic. The author would like to thank the referees for various suggestions to improve the
exposition
XUV spectroscopic characterization of warm dense aluminum plasmas generated by the free-electron-laser FLASH
No full textWe report on experiments aimed at the generation and characterization of solid density plasmas at the free-electron laser FLASH in Hamburg. Aluminum samples were irradiated with XUV pulses at 13.5 nm wavelength (92 eV photon energy). The pulses with duration of a few tens of femtoseconds and pulse energy up to 100 mu J are focused to intensities ranging between 10(13) and 10(17) W/cm(2). We investigate the absorption and temporal evolution of the sample under irradiation by use of XUV and optical spectroscopy. We discuss the origin of saturable absorption, radiative decay, bremsstrahlung and atomic and ionic line emission. Our experimental results are in good agreement with simulations.</p
Wavelets in Economics and Finance: Past and Future
No full textIn this paper I review what insights we have gained about economic and financial relationships from the use of wavelets and speculate on what further insights we may gain in the future. Wavelets are treated as a "lens" that enables the researcher to explore relationships that previously were unobservable.WAVELETS; TIME SCALE; FORECASTS; OSCILLATING FREQUENCIES; DENOISING; CONSUMPTION FUNCTION; INCOME VELOCITY; TIME VARYING DELAYS
lecture notes on concentrated graduate courses
No full textThe Geometry and Moduli of K3 Surfaces (A. Harder, A. Thompson) -- Picard Ranks of K3 Surfaces of BHK Type (T. Kelly) -- Reflexive Polytopes and Lattice-Polarized K3 Surfaces (U. Whitcher) -- An Introduction to Hodge Theory (S.A. Filippini, H. Ruddat, A. Thompson) -- Introduction to Nonabelian Hodge Theory (A. Garcia-Raboso, S. Rayan) -- Algebraic and Arithmetic Properties of Period Maps (M. Kerr) -- Mirror Symmetry in Physics (C. Quigley) -- Introduction to Gromov–Witten Theory (S. Rose).- Introduction to Donaldson–Thomas and Stable Pair Invariants (M. van Garrel).- Donaldson–Thomas Invariants and Wall-Crossing Formulas (Y. Zhu).- Enumerative Aspects of the Gross–Siebert Program (M. van Garrel, D.P. Overholser, H. Ruddat).- Introduction to Modular Forms (S. Rose).- Lectures on Holomorphic Anomaly Equations (A. Kanazawa, J. Zhou) -- Polynomial Structure of Topological Partition Functions (J. Zhou).- Introduction to Arithmetic Mirror Symmetry (A. Perunicic
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