4,176 research outputs found
Program on stimulating operational private sector use of Earth observation satellite information
Ideas for new businesses specializing in using remote sensing and computerized spatial data systems were developd. Each such business serves as an 'information middleman', buying raw satellite or aircraft imagery, processing these data, combining them in a computer system with customer-specific information, and marketing the resulting information products. Examples of the businesses the project designed are: (1) an agricultural facility site evaluation firm; (2) a mass media grocery price and supply analyst and forecaster; (3) a management service for privately held woodlots; (4) a brokerage for insulation and roofing contractors, based on infrared imagery; (5) an expanded real estate information service. In addition, more than twenty-five other commercially attractive ideas in agribusiness, forestry, mining, real estate, urban planning and redevelopment, and consumer information were created. The commercial feasibility of the five business was assessed. This assessment included market surveys, revenue projections, cost analyses, and profitability studies. The results show that there are large and enthusiastic markets willing to pay for the services these businesses offer, and that the businesses could operate profitably
Program on stimulating operational private sector use of Earth observation satellite data
There are no author-identified significant results in this report
Infrared magneto-optical properties of (III,Mn)V ferromagetic semiconductors
We present a theoretical study of the infrared magneto-optical properties of
ferromagnetic (III,Mn)V semiconductors. Our analysis combines the kinetic
exchange model for (III,Mn)V ferromagnetism with Kubo linear response theory
and Born approximation estimates for the effect of disorder on the valence band
quasiparticles. We predict a prominent feature in the ac-Hall conductivity at a
frequency that varies over the range from 200 to 400 meV, depending on Mn and
carrier densities, and is associated with transitions between heavy-hole and
light-hole bands. In its zero frequency limit, our Hall conductivity reduces to
the -space Berry's phase value predicted by a recent theory of the
anomalous Hall effect that is able to account quantitatively for experiment. We
compute theoretical estimates for magnetic circular dichroism, Faraday
rotation, and Kerr effect parameters as a function of Mn concentration and free
carrier density. The mid-infrared response feature is present in each of these
magneto-optical effects.Comment: 11 pages, 5 figure
Excited states of linear polyenes
We present density matrix renormalisation group calculations of the Pariser-
Parr-Pople-Peierls model of linear polyenes within the adiabatic approximation.
We calculate the vertical and relaxed transition energies, and relaxed
geometries for various excitations on long chains. The triplet (3Bu+) and even-
parity singlet (2Ag+) states have a 2-soliton and 4-soliton form, respectively,
both with large relaxation energies. The dipole-allowed (1Bu-) state forms an
exciton-polaron and has a very small relaxation energy. The relaxed energy of
the 2Ag+ state lies below that of the 1Bu- state. We observe an attraction
between the soliton-antisoliton pairs in the 2Ag+ state. The calculated
excitation energies agree well with the observed values for polyene oligomers;
the agreement with polyacetylene thin films is less good, and we comment on the
possible sources of the discrepencies. The photoinduced absorption is
interpreted. The spin-spin correlation function shows that the unpaired spins
coincide with the geometrical soliton positions. We study the roles of
electron-electron interactions and electron-lattice coupling in determining the
excitation energies and soliton structures. The electronic interactions play
the key role in determining the ground state dimerisation and the excited state
transition energies.Comment: LaTeX, 15 pages, 9 figure
Capillary pressure of van der Waals liquid nanodrops
The dependence of the surface tension on a nanodrop radius is important for
the new-phase formation process. It is demonstrated that the famous Tolman
formula is not unique and the size-dependence of the surface tension can
distinct for different systems. The analysis is based on a relationship between
the surface tension and disjoining pressure in nanodrops. It is shown that the
van der Waals interactions do not affect the new-phase formation thermodynamics
since the effect of the disjoining pressure and size-dependent component of the
surface tension cancel each other.Comment: The paper is dedicated to the 80th anniversary of A.I. Rusano
Improved bone defect healing by a superagonistic GDF5 variant derived from a patient with multiple synostoses syndrome
Multiple synostoses syndrome 2 (SYNS2) is a rare genetic disease characterized by multiple fusions of the joints of the extremities, like phalangeal joints, carpal and tarsal joints or the knee and elbows. SYNS2 is caused by point mutations in the Growth and Differentiation Factor 5 (GDF5), which plays an essential role during skeletal development and regeneration. We selected one of the SYNS2-causing GDF5 mutations, p.N445T, which is known to destabilize the interaction with the Bone Morphogenetic Protein (BMP) antagonist NOGGIN (NOG), in order to generate the superagonistic GDF5 variant GDF5(N445T). In this study, we tested its capacity to support regeneration in a rat critical-sized defect model in vivo. MicroCT and histological analyses indicate that GDF5(N445T)-treated defects show faster and more efficient healing compared to GDF5 wild type (GDF5(wt))-treated defects. Microarray-based gene expression and quantitative PCR analyses from callus tissue point to a specific acceleration of the early phases of bone healing, comprising the inflammation and chondrogenesis phase. These results support the concept that disease-deduced growth factor variants are promising lead structures for novel therapeutics with improved clinical activities
Associated production of light gravitinos in e^+e^- and e^-\gamma collisions
Light gravitino productions in association with a neutralino (selectron) in
e^+e^- (e^-\gamma) collisions are restudied in a scenario that the lightest
supersymmetric particle is a gravitino and the produced neutralino (selectron)
promptly decays into a photon (electron) and a gravitino. We explicitly give
the helicity amplitudes for the production processes by using the effective
goldstino interaction Lagrangian, and present the cross sections with different
collision energies and mass spectra. We also examine selection efficiencies by
kinematical cuts and beam polarizations for the signal and background
processes, and show that the energy and angular distributions of the photon
(electron) can explore the mass of the t-channel exchange particle as well as
the mass of the decaying particle at a future e^+e^- (e^-\gamma) collider.Comment: 12 pages, 12 figures, 4 tables; references added, version to appear
in EPJ
Omacetaxine may have a role in chronic myeloid leukaemia eradication through downregulation of Mcl-1 and induction of apoptosis in stem/progenitor cells
Chronic myeloid leukaemia (CML) is maintained by a rare population of tyrosine kinase inhibitor (TKI)-insensitive malignant stem cells. Our long-term aim is to find a BcrAbl-independent drug that can be combined with a TKI to improve overall disease response in chronic-phase CML. Omacetaxine mepesuccinate, a first in class cetaxine, has been evaluated by clinical trials in TKI-insensitive/resistant CML. Omacetaxine inhibits synthesis of anti-apoptotic proteins of the Bcl-2 family, including (myeloid cell leukaemia) Mcl-1, leading to cell death. Omacetaxine effectively induced apoptosis in primary CML stem cells (CD34<sup>+</sup>38<sup>lo</sup>) by downregulation of Mcl-1 protein. In contrast to our previous findings with TKIs, omacetaxine did not accumulate undivided cells <i>in vitro</i>. Furthermore, the functionality of surviving stem cells following omacetaxine exposure was significantly reduced in a dose-dependant manner, as determined by colony forming cell and the more stringent long-term culture initiating cell colony assays. This stem cell-directed activity was not limited to CML stem cells as both normal and non-CML CD34<sup>+</sup> cells were sensitive to inhibition. Thus, although omacetaxine is not leukaemia stem cell specific, its ability to induce apoptosis of leukaemic stem cells distinguishes it from TKIs and creates the potential for a curative strategy for persistent disease
Ultra-low carrier concentration and surface dominant transport in Sb-doped Bi2Se3 topological insulator nanoribbons
A topological insulator is a new state of matter, possessing gapless
spin-locking surface states across the bulk band gap which has created new
opportunities from novel electronics to energy conversion. However, the large
concentration of bulk residual carriers has been a major challenge for
revealing the property of the topological surface state via electron transport
measurement. Here we report surface state dominated transport in Sb-doped
Bi2Se3 nanoribbons with very low bulk electron concentrations. In the
nanoribbons with sub-10nm thickness protected by a ZnO layer, we demonstrate
complete control of their top and bottom surfaces near the Dirac point,
achieving the lowest carrier concentration of 2x10^11/cm2 reported in
three-dimensional (3D) topological insulators. The Sb-doped Bi2Se3
nanostructures provide an attractive materials platform to study fundamental
physics in topological insulators, as well as future applications.Comment: 5 pages, 4 figures, 1 tabl
Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data
Herein the transient lunar phenomena (TLP) report database is subjected to a
discriminating statistical filter robust against sites of spurious reports, and
produces a restricted sample that may be largely reliable. This subset is
highly correlated geographically with the catalog of outgassing events seen by
the Apollo 15, 16 and Lunar Prospector alpha-particle spectrometers for
episodic Rn-222 gas release. Both this robust TLP sample and even the larger,
unfiltered sample are highly correlated with the boundary between mare and
highlands, as are both deep and shallow moonquakes, as well as Po-210, a
long-lived product of Rn-222 decay and a further tracer of outgassing. This
offers another significant correlation relating TLPs and outgassing, and may
tie some of this activity to sagging mare basalt plains (perhaps mascons).
Additionally, low-level but likely significant TLP activity is connected to
recent, major impact craters (while moonquakes are not), which may indicate the
effects of cracks caused by the impacts, or perhaps avalanches, allowing
release of gas. The majority of TLP (and Rn-222) activity, however, is confined
to one site that produced much of the basalt in the Procellarum Terrane, and it
seems plausible that this TLP activity may be tied to residual outgassing from
the formerly largest volcanic ffusion sites from the deep lunar interior. With
the coming in the next few years of robotic spacecraft followed by human
exploration, the study of TLPs and outgassing is both promising and imperiled.
We will have an unprecedented pportunity to study lunar outgassing, but will
also deal with a greater burden of anthropogenic lunar gas than ever produced.
There is a pressing need to study lunar atmosphere and its sources while still
pristine. [Abstract abridged.]Comment: 35 pages, 3 figures, submitted to Icarus. Other papers in series
found at http://www.astro.columbia.edu/~arlin/TLP
- …