2,430 research outputs found
Derived categories of Burniat surfaces and exceptional collections
We construct an exceptional collection of maximal possible length
6 on any of the Burniat surfaces with , a 4-dimensional family of
surfaces of general type with . We also calculate the DG algebra of
endomorphisms of this collection and show that the subcategory generated by
this collection is the same for all Burniat surfaces.
The semiorthogonal complement of is an "almost
phantom" category: it has trivial Hochschild homology, and K_0(\mathcal
A)=\bZ_2^6.Comment: 15 pages, 1 figure; further remarks expande
Geometric collections and Castelnuovo-Mumford Regularity
The paper begins by overviewing the basic facts on geometric exceptional
collections. Then, we derive, for any coherent sheaf \cF on a smooth
projective variety with a geometric collection, two spectral sequences: the
first one abuts to \cF and the second one to its cohomology. The main goal of
the paper is to generalize Castelnuovo-Mumford regularity for coherent sheaves
on projective spaces to coherent sheaves on smooth projective varieties
with a geometric collection . We define the notion of regularity of a
coherent sheaf \cF on with respect to . We show that the basic
formal properties of the Castelnuovo-Mumford regularity of coherent sheaves
over projective spaces continue to hold in this new setting and we show that in
case of coherent sheaves on \PP^n and for a suitable geometric collection of
coherent sheaves on \PP^n both notions of regularity coincide. Finally, we
carefully study the regularity of coherent sheaves on a smooth quadric
hypersurface Q_n \subset \PP^{n+1} ( odd) with respect to a suitable
geometric collection and we compare it with the Castelnuovo-Mumford regularity
of their extension by zero in \PP^{n+1}.Comment: To appear in Math. Proc. Cambridg
Bound, virtual and resonance -matrix poles from the Schr\"odinger equation
A general method, which we call the potential -matrix pole method, is
developed for obtaining the -matrix pole parameters for bound, virtual and
resonant states based on numerical solutions of the Schr\"odinger equation.
This method is well-known for bound states. In this work we generalize it for
resonant and virtual states, although the corresponding solutions increase
exponentially when . Concrete calculations are performed for the
ground and the first excited states of , the resonance
states (, ), low-lying states of and
, and the subthreshold resonances in the proton-proton system. We
also demonstrate that in the case the broad resonances their energy and width
can be found from the fitting of the experimental phase shifts using the
analytical expression for the elastic scattering -matrix. We compare the
-matrix pole and the -matrix for broad resonance in
Comment: 14 pages, 5 figures (figures 3 and 4 consist of two figures each) and
4 table
Pauli spin blockade in CMOS double quantum dot devices
Silicon quantum dots are attractive candidates for the development of
scalable, spin-based qubits. Pauli spin blockade in double quantum dots
provides an efficient, temperature independent mechanism for qubit readout.
Here we report on transport experiments in double gate nanowire transistors
issued from a CMOS process on 300 mm silicon-on-insulator wafers. At low
temperature the devices behave as two few-electron quantum dots in series. We
observe signatures of Pauli spin blockade with a singlet-triplet splitting
ranging from 0.3 to 1.3 meV. Magneto-transport measurements show that
transitions which conserve spin are shown to be magnetic-field independent up
to B = 6 T.Comment: 5 pages , 4 figure
Storage-ring measurement of the hyperfine induced 47Ti18+(2s 2p 3P0 -> 2s2 1S0) transition rate
The hyperfine induced 2s 2p 3P0 > 2s2 1S0 transition rate AHFI in
berylliumlike 47Ti18+ was measured. Resonant electron-ion recombination in a
heavy-ion storage ring was employed to monitor the time dependent population of
the 3P0 state. The experimental value AHFI=0.56(3)/s is almost 60% larger than
theoretically predicted.Comment: 4 pages. 3 figures, 1 table, accepted for publication in Physical
Review Letter
Big data analytics for continuous assessment of astronaut health risk and its application to human-in-the-loop (HITL) related aerospace
© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. The man-instrumentation-equipment-vehicle-environment ecosystem is complex in aerospace missions. Health status of the individual has important implications on decision making and performance that should be factored into assessments for probability of success/risk of failure both in offline and real-time models. To date probabilistic models have not considered the dynamic nature of health status. Big Data analytics is enabling new forms of analytics to assess health status in real-time. There is great potential to integrate dynamic health status information with platforms assessing risk and the probability of success for dynamic individualized real-time probabilistic predictive risk assessment. In this research we present an approach utilizing Big Data analytics to enable continuous assessment of astronaut health risk and show its implications for integration with HITL related aerospace mission
A comprehensive evaluation of water uptake on atmospherically relevant mineral surfaces: DRIFT spectroscopy, thermogravimetric analysis and aerosol growth measurements
The hygroscopicity of mineral aerosol samples has been examined by three independent methods: diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis and differential mobility analysis. All three methods allow an evaluation of the water coverage of two samples, CaCO<sub>3</sub> and Arizona Test dust, as a function of relative humidity. For the first time, a correlation between absolute gravimetric measurements and the other two (indirect) methods has been established. Water uptake isotherms were reliably determined for both solids which at 298 K and 80% relative humidity exhibited similar coverages of ~4 monolayers. However, the behaviour at low relative humidity was markedly different in the two cases, with Arizona Test Dust showing a substantially higher affinity for water in the contact layer. This is understandable in terms of the chemical composition of these two materials. The mobility analysis results are in good accord with field observations and with our own spectroscopic and gravimetric measurements. These findings are of value for an understanding of atmospheric chemical processes
A survey of Hirota's difference equations
A review of selected topics in Hirota's bilinear difference equation (HBDE)
is given. This famous 3-dimensional difference equation is known to provide a
canonical integrable discretization for most important types of soliton
equations. Similarly to the continuous theory, HBDE is a member of an infinite
hierarchy. The central point of our exposition is a discrete version of the
zero curvature condition explicitly written in the form of discrete
Zakharov-Shabat equations for M-operators realized as difference or
pseudo-difference operators. A unified approach to various types of M-operators
and zero curvature representations is suggested. Different reductions of HBDE
to 2-dimensional equations are considered. Among them discrete counterparts of
the KdV, sine-Gordon, Toda chain, relativistic Toda chain and other typical
examples are discussed in detail.Comment: LaTeX, 43 pages, LaTeX figures (with emlines2.sty
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