8,894 research outputs found
Lipschitz stability for the electrostatic inverse boundary value problem with piecewise linear conductivities
We consider the electrostatic inverse boundary value problem also known as
electrical impedance tomography (EIT) for the case where the conductivity is a
piecewise linear function on a domain and we show
that a Lipschitz stability estimate for the conductivity in terms of the local
Dirichlet-to-Neumann map holds true.Comment: 28 pages. arXiv admin note: text overlap with arXiv:1405.047
Monodromy in the CMB: Gravity Waves and String Inflation
We present a simple mechanism for obtaining large-field inflation, and hence
a gravitational wave signature, from string theory compactified on twisted
tori. For Nil manifolds, we obtain a leading inflationary potential
proportional to phi^(2/3) in terms of the canonically normalized field phi,
yielding predictions for the tilt of the power spectrum and the
tensor-to-scalar ratio, and with 60
e-foldings of inflation; we note also the possibility of a variant with a
candidate inflaton potential proportional to phi^(2/5). The basic mechanism
involved in extending the field range -- monodromy in D-branes as they move in
circles on the manifold -- arises in a more general class of compactifications,
though our methods for controlling the corrections to the slow-roll parameters
require additional symmetries.Comment: 43 pages, latex. 4 figure
On the ubiquity of molecular anions in the dense interstellar medium
Results are presented from a survey for molecular anions in seven nearby
Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H- is
detected in all seven target sources, including four sources where no anions
have been previously detected: L1172, L1389, L1495B and TMC-1C. The C6H-/C6H
column density ratio is greater than about 1.0% in every source, with a mean
value of 3.0% (and standard deviation 0.92%). Combined with previous
detections, our results show that anions are ubiquitous in dense clouds
wherever C6H is present. The C6H-/C6H ratio is found to show a positive
correlation with molecular hydrogen number density, and with the apparent age
of the cloud. We also report the first detection of C4H- in TMC-1 (at 4.8-sigma
confidence), and derive an anion-to-neutral ratio C4H-/C4H = (1.2 +- 0.4) x
10^-5 (= 0.0012 +- 0.0004%). Such a low value compared with C6H- highlights the
need for a revised radiative electron attachment rate for C4H. Chemical model
calculations show that the observed C4H- could be produced as a result of
reactions of oxygen atoms with C5H- and C6H-
Probing subtle fluorescence dynamics in cellular proteins by streak camera based Fluorescence Lifetime Imaging Microscopy
We report the cell biological applications of a recently developed
multiphoton fluorescence lifetime imaging microscopy system using a streak
camera (StreakFLIM). The system was calibrated with standard fluorophore
specimens and was shown to have high accuracy and reproducibility. We
demonstrate the applicability of this instrument in living cells for measuring
the effects of protein targeting and point mutations in the protein sequence
which are not obtainable in conventional intensity based fluorescence
microscopy methods. We discuss the relevance of such time resolved information
in quantitative energy transfer microscopy and in measurement of the parameters
characterizing intracellular physiology
Corruption in the Former Soviet Union and the Problems It Represents to the Democratization Process
The purpose of this study is to better understand the phenomenon of corruption in the former member states of the Soviet Union and the implications for a successful completion of democratic transition and consolidation. The complex political and economic situation is constantly changing, and although well over a decade has passed since the official collapse of the Soviet Union in 1991, the future of the majority of the fifteen former Soviet Union countries remains - at best - questionable and uncertain. This study is concentrated on comparing different rates of progress towards democratization in several of the former Soviet Union countries, including Russia, Belarus, and the Baltic States. This study will show how the existence of systemic corruption is most widespread in transitioning economies, but measuring the exact extent and impact of it on these societies is very difficult. Empirical research has provided results that are estimates, however, and cannot be classified as an exact reflection of the actual situation. Previous research done in this field presents diverse approaches on how to effectively reduce the rates of corruption in these newly developed countries, all of which carry heavy political, economic, and social baggage. This research will show evidence that progress towards democratization and marketization has not been as timely as was once predicted by Western leaders, academia, and others. The era and legacy of communism has clenched its claws into this region of the world, and is unable to let go of its deeply imbedded socialist beliefs and values. Corruption will never be eliminated in its entirety. It can, however, be reduced through necessary policy implementation and the evolving development of the civil society. This must occur if democratization is to take its course
- …