6,861 research outputs found
Lead salt diode lasers and development of tunable solid state lasers for remote sensing
Extensive studies of the output characteristics of single quantum well lead-telluride lasers developed at the General Motors Research Laboratories were carried out. Threshold currents, output powers and line structures were measured as a function of temperature. Very low-current lasing thresholds, record high operating temperatures and over 30% tuning ranges were achieved. Excellent reproducibilities, good far-field patterns and reasonable linewidths (approx. 500 kHz) were found
Generation of electron spin polarization in disordered organic semiconductors
The generation mechanisms of electron spin polarization (ESP) of charge
carriers (electrons and holes, called "doublets") in doublet-doublet
recombination and triplet-doublet quenching in disordered organic
semiconductors are analyzed in detail. The ESP is assumed to result from
quantum transitions between the states of the spin Hamiltonian of the pair of
interacting particles. The value of the ESP is essentially determined by the
mechanism of relative motion of particles. In our work we have considered the
cage and free diffusion models. The effect of possible attractive
spin-independent interactions between particles is also analyzed. Estimation
with obtained formulas shows that the proposed mechanisms can lead to a fairly
strong ESP much larger than the thermal one (at room temperatures)Comment: 10 pages, 3 figure
Magnetic field effects on electron-hole recombination in disordered organic semiconductors
Characteristic properties of magnetic field effects on spin selective
geminate and bulk electron-hole polaron pair (PP) recombination are analyzed in
detail within the approach based on the stochastic Liouville equation. Simple
expressions for the magnetic field (B) dependence of recombination yield and
rate are derived within two models of relative PP motion: free diffusion and
diffusion in the presence of well (cage). The spin evolution of PPs is
described taking in account the relaxation induced by hyperfine interaction,
anisotropic part of the Zeeman interaction induced, as well as -mechanism. A large variety of the -dependences of the recombination yield
and rate is obtained depending on the relative weights of
above-mentioned mechanisms. The proposed general method and derived particular
formulas are shown to be quite useful for the analysis of recent experimental
results.Comment: 12 pages, 3 figure
Special complex manifolds
We introduce the notion of a special complex manifold: a complex manifold
(M,J) with a flat torsionfree connection \nabla such that (\nabla J) is
symmetric. A special symplectic manifold is then defined as a special complex
manifold together with a \nabla-parallel symplectic form \omega . This
generalises Freed's definition of (affine) special K\"ahler manifolds. We also
define projective versions of all these geometries. Our main result is an
extrinsic realisation of all simply connected (affine or projective) special
complex, symplectic and K\"ahler manifolds. We prove that the above three types
of special geometry are completely solvable, in the sense that they are locally
defined by free holomorphic data. In fact, any special complex manifold is
locally realised as the image of a holomorphic 1-form \alpha : C^n \to T^* C^n.
Such a realisation induces a canonical \nabla-parallel symplectic structure on
M and any special symplectic manifold is locally obtained this way. Special
K\"ahler manifolds are realised as complex Lagrangian submanifolds and
correspond to closed forms \alpha. Finally, we discuss the natural geometric
structures on the cotangent bundle of a special symplectic manifold, which
generalise the hyper-K\"ahler structure on the cotangent bundle of a special
K\"ahler manifold.Comment: 24 pages, latex, section 3 revised (v2), modified Abstract and
Introduction, version to appear in J. Geom. Phy
A Large k Asymptotics of Witten's Invariant of Seifert Manifolds
We calculate a large asymptotic expansion of the exact surgery formula
for Witten's invariant of Seifert manifolds. The contributions of all
flat connections are identified. An agreement with the 1-loop formula is
checked. A contribution of the irreducible connections appears to contain only
a finite number of terms in the asymptotic series. A 2-loop correction to the
contribution of the trivial connection is found to be proportional to Casson's
invariant.Comment: 51 pages (Some changes are made to the Discussion section. A surgery
formula for perturbative corrections to the contribution of the trivial
connection is suggested.
A latent class analysis of parental bipolar disorder: examining associations with offspring psychopathology
Bipolar disorder (BD) is highly heterogeneous, and course variations are associated with patient outcomes. This diagnostic complexity challenges identification of patients in greatest need of intervention. Additionally, course variations have implications for offspring risk. First, latent class analysis (LCA) categorized parents with BD based on salient illness characteristics: BD type, onset age, polarity of index episode, pole of majority of episodes, rapid cycling, psychosis, anxiety comorbidity, and substance dependence. Fit indices favored three parental classes with some substantively meaningful patterns. Two classes, labeled “Earlier-Onset Bipolar-I” (EO-I) and “Earlier-Onset Bipolar-II” (EO-II), comprised parents who had a mean onset age in mid-adolescence, with EO-I primarily BD-I parents and EO-II entirely BD-II parents. The third class, labeled “Later-Onset BD” (LO) had an average onset age in adulthood. Classes also varied on probability of anxiety comorbidity, substance dependence, psychosis, rapid cycling, and pole of majority of episodes. Second, we examined rates of disorders in offspring (ages 4–33, Mage=13.46) based on parental latent class membership. Differences emerged for offspring anxiety disorders only such that offspring of EO-I and EO-II parents had higher rates, compared to offspring of LO parents, particularly for daughters. Findings may enhance understanding of BD and its nosologyThis study was funded by two Brain & Behavior Research Foundation (formerly NARSAD) Independent Investigator Awards (PI: Nierenberg), a Brain & Behavior Research Foundation Young Investigator Award (PI: Henin) generously supported in part by the SHINE Initiative, and an MGH Claflin Award (PI: Henin). We thank David A. Langer, Ph.D., Thomas M. Olino, Ph.D., and Meredith Lotz Wallace, Ph.D. for their consultation. (Brain & Behavior Research Foundation; Brain & Behavior Research Foundation Young Investigator Award; SHINE Initiative; MGH Claflin Award)Accepted manuscrip
Writing Winning Business Proposal -3/E.
This is the book that gives you the skills, tools, tactics, and strategies you need to write outstanding proposals of all kinds. Based on a proven system used by A.T. Kearny and KPMG to train their consultants, this acclaimed resource offers general guidance and specific tactics for different types of business proposals, such as seeking approval for projects, market surveys, or grants.
Whether you’re seeking approval or funding for projects or persuading slients to deepen their commitment to your business, Writing Winning Business Proposals is the reference you need to get what you want
- …