2,460 research outputs found
What can be patented? Technological innovation and the contemporary mess in patent law
The question of what types of inventions may be patented has becom
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Realising the therapeutic potential of neuroactive steroid modulators of the GABA<sub>A</sub> receptor
In the 1980s particular endogenous metabolites of progesterone and of deoxycorticosterone were revealed to be potent, efficacious, positive allosteric modulators (PAMs) of the GABAA receptor (GABAAR). These reports were followed by the discovery that such steroids may be synthesised not only in peripheral endocrine glands, but locally in the central nervous system (CNS), to potentially act as paracrine, or autocrine "neurosteroid" messengers, thereby fine tuning neuronal inhibition. These discoveries triggered enthusiasm to elucidate the physiological role of such neurosteroids and explore whether their levels may be perturbed in particular psychiatric and neurological disorders. In preclinical studies the GABAAR-active steroids were shown to exhibit anxiolytic, anticonvulsant, analgesic and sedative properties and at relatively high doses to induce a state of general anaesthesia. Collectively, these findings encouraged efforts to investigate the therapeutic potential of neurosteroids and related synthetic analogues. However, following over 30 years of investigation, realising their possible medical potential has proved challenging. The recent FDA approval for the natural neurosteroid allopregnanolone (brexanolone) to treat postpartum depression (PPD) should trigger renewed enthusiasm for neurosteroid research. Here we focus on the influence of neuroactive steroids on GABA-ergic signalling and on the challenges faced in developing such steroids as anaesthetics, sedatives, analgesics, anticonvulsants, antidepressants and as treatments for neurodegenerative disorders
On the dynamics of stochastic nonlinear dispersive partial differential equations
This thesis contributes towards the well-posedness theory of stochastic dispersive
partial differential equations. Our investigation focuses on initial value problems as
sociated with the stochastic nonlinear Schro¨dinger (SNLS) and stochastic Korteweg
de Vries (SKdV) equations. We divide this thesis into four main topics, which are
the contents of Chapters 2–5.
Chapter 2 is concerned with the SNLS posed on the d-dimensional tori with
either additive or multiplicative stochastic forcing. In particular, we prove local-in
time well-posedness for initial data and noise at subcritical regularities. We are also
able to extend this to global-in-time well-posedness at energy subcritical regularity
for certain cases. In the next two chapters, we focus on SNLS posed on the d
dimensional Euclidean space with additive noise. In Chapter 3, we prove local well
posedness with the noise at supercritical regularity while the initial data stays at
critical regularity. In Chapter 4, we restrict our attention to dimension 4 and study
SNLS with non-vanishing boundary conditions. In particular, we use perturbative techniques to prove global well-posedness with data in H1(R4) + 1. In Chapter 5, we move on from SNLS to SKdV, where we prove L2(T)-global well-posedness of SKdV with multiplicative noise on the circle. We also verify that
a result on the stabilisation of noise by Tsutsumi [84] continues to hold in our low
regularity setting
Endogenous innovation, outward-bound international patenting and national economic development
In this paper we argue that countries whose residents exhibit a relativel
Perturbative behaviour of a vortex in a trapped Bose-Einstein condensate
We derive a set of equations that describe the shape and behaviour of a
single perturbed vortex line in a Bose-Einstein condensate. Through the use of
a matched asymptotic expansion and a unique coordinate transform a relation for
a vortex's velocity, anywhere along the line, is found in terms of the
trapping, rotation, and distortion of the line at that location. This relation
is then used to find a set of differential equations that give the line's
specific shape and motion. This work corrects a previous similar derivation by
Anatoly A. Svidzinsky and Alexander L. Fetter [Phys. Rev. A \textbf{62}, 063617
(2000)], and enables a comparison with recent numerical results.Comment: 12 pages with 3 figure
Density functional theory study of the nematic-isotropic transition in an hybrid cell
We have employed the Density Functional Theory formalism to investigate the
nematic-isotropic capillary transitions of a nematogen confined by walls that
favor antagonist orientations to the liquid crystal molecules (hybrid cell). We
analyse the behavior of the capillary transition as a function of the
fluid-substrate interactions and the pore width. In addition to the usual
capillary transition between isotropic-like to nematic-like states, we find
that this transition can be suppressed when one substrate is wet by the
isotropic phase and the other by the nematic phase. Under this condition the
system presents interface-like states which allow to continuously transform the
nematic-like phase to the isotropic-like phase without undergoing a phase
transition. Two different mechanisms for the disappearance of the capillary
transition are identified. When the director of the nematic-like state is
homogeneously planar-anchored with respect to the substrates, the capillary
transition ends up in a critical point. This scenario is analogous to the
observed in Ising models when confined in slit pores with opposing surface
fields which have critical wetting transitions. When the nematic-like state has
a linearly distorted director field, the capillary transition continuously
transforms in a transition between two nematic-like states.Comment: 31 pages, 10 figures, submitted to J. Chem. Phy
The value of hippocampal and temporal horn volumes and rates of change in predicting future conversion to AD.
Hippocampal pathology occurs early in Alzheimer disease (AD), and atrophy, measured by volumes and volume changes, may predict which subjects will develop AD. Measures of the temporal horn (TH), which is situated adjacent to the hippocampus, may also indicate early changes in AD. Previous studies suggest that these metrics can predict conversion from amnestic mild cognitive impairment (MCI) to AD with conversion and volume change measured concurrently. However, the ability of these metrics to predict future conversion has not been investigated. We compared the abilities of hippocampal, TH, and global measures to predict future conversion from MCI to AD. TH, hippocampi, whole brain, and ventricles were measured using baseline and 12-month scans. Boundary shift integral was used to measure the rate of change. We investigated the prediction of conversion between 12 and 24 months in subjects classified as MCI from baseline to 12 months. All measures were predictive of future conversion. Local and global rates of change were similarly predictive of conversion. There was evidence that the TH expansion rate is more predictive than the hippocampal atrophy rate (P=0.023) and that the TH expansion rate is more predictive than the TH volume (P=0.036). Prodromal atrophy rates may be useful predictors of future conversion to sporadic AD from amnestic MCI
Global innovation and competition in quantum technology, viewed through the lens of patents and artificial intelligence
Suppression of Kelvon-induced decay of quantized vortices in oblate Bose-Einstein Condensates
We study the Kelvin mode excitations on a vortex line in a three-dimensional
trapped Bose-Einstein condensate at finite temperature. Our stochastic
Gross-Pitaevskii simulations show that the activation of these modes can be
suppressed by tightening the confinement along the direction of the vortex
line, leading to a strong suppression in the vortex decay rate as the system
enters a regime of two-dimensional vortex dynamics. As the system approaches
the condensation transition temperature we find that the vortex decay rate is
strongly sensitive to dimensionality and temperature, observing a large
enhancement for quasi-two-dimensional traps. Three-dimensional simulations of
the recent vortex dipole decay experiment of Neely et al. [Phys. Rev. Lett.
104, 160401 (2010)] confirm two-dimensional vortex dynamics, and predict a
dipole lifetime consistent with experimental observations and suppression of
Kelvon-induced vortex decay in highly oblate condensates.Comment: 8 pages, 8 figure
A new chiral electro-optic effect: Sum-frequency generation from optically active liquids in the presence of a dc electric field
We report the observation of sum-frequency signals that depend linearly on an
applied electrostatic field and that change sign with the handedness of an
optically active solution. This recently predicted chiral electro-optic effect
exists in the electric-dipole approximation. The static electric field gives
rise to an electric-field-induced sum-frequency signal (an achiral third-order
process) that interferes with the chirality-specific sum-frequency at
second-order. The cross-terms linear in the electrostatic field constitute the
effect and may be used to determine the absolute sign of second- and
third-order nonlinear optical susceptibilities in isotropic media.Comment: Submitted to Physical Revie
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