Tradeoffs in the utility of learned knowledge

Planning systems which make use of domain theories can produce more accurate plans and achieve more goals as the quality of their domain knowledge improves. MTR, a multi-strategy learning system, was designed to learn from system failures and improve domain knowledge used in planning. However, augmented domain knowledge can decrease planning efficiency. We describe how improved knowledge that becomes expensive to use can be approximated to yield calculated tradeoffs in accuracy and efficiency

Motion Control of an Open Container with Slosh Constraints

General motion control of conveyor belts does not present difficulties. When the conveyor belt carries open containers filled with liquid, significant analysis needs to be carried out to design controllers. The objective of this thesis was to design a control system which will allow an open container filled with liquid to be transferred between two stations as fast as possible and without excessive slosh causing the liquid to spill out of the container. This control problem has applications to industrial processing facilities, where open containers are carried by a conveyor belt. The speed at which the open container can be transferred between stations has a direct impact on productivity. The thesis involves determination of the plant (conveyor belt dynamics and the container filled with liquid) model using system identification techniques and examination of candidate control techniques. Simulation results have been shown to validate the approac

A case of hereditary sensory and autonomic neuropathy type 4 presenting with chronic trophic ulcers

Hereditary Sensory and Autonomic Neuropathy (HSAN) is a rare group of diseases involving varying degrees of peripheral nervous system. It is classified into five main types. HSAN type 4 is associated with insensitivity to pain and temperature and anihidrosis. The method of this study was to authors present a case report of a 3 year-old boy with Hereditary Sensory and Autonomic Neuropathy Type 4 presenting with chronic ulcers. Conclusions of this study was to HSAN type IV is a rare condition. There is no definitive treatment available presently for this condition

Semiclassical spin liquid state of easy axis Kagome antiferromagnets

Motivated by recent experiments on Nd-langasite, we consider the effect of strong easy axis single-ion anisotropy $D$ on $S > 3/2$ spins interacting with antiferromagnetic exchange $J$ on the Kagome lattice. When $T \ll DS^2$, the collinear low energy states selected by the anisotropy map on to configurations of the classical Kagome lattice Ising antiferromagnet. However, the low temperature limit is quite different from the cooperative Ising paramagnet that obtains classically for $T \ll JS^2$. We find that sub-leading ${\mathcal O}(J^3S/D^2)$ multi-spin interactions arising from the transverse quantum dynamics result in a crossover from an intermediate temperature classical cooperative Ising paramagnet to a semiclassical spin liquid with distinct short-ranged correlations for $T \ll J^3S/D^2$.Comment: 4 pages, 3 eps figure

There is No Free Lunch: Tradeoffs in the Utility of Learned Knowledge

With the recent introduction of learning in integrated systems, there is a need to measure the utility of learned knowledge for these more complex systems. A difficulty arrises when there are multiple, possibly conflicting, utility metrics to be measured. In this paper, we present schemes which trade off conflicting utility metrics in order to achieve some global performance objectives. In particular, we present a case study of a multi-strategy machine learning system, mutual theory refinement, which refines world models for an integrated reactive system, the Entropy Reduction Engine. We provide experimental results on the utility of learned knowledge in two conflicting metrics - improved accuracy and degraded efficiency. We then demonstrate two ways to trade off these metrics. In each, some learned knowledge is either approximated or dynamically 'forgotten' so as to improve efficiency while degrading accuracy only slightly

Symmetry breaking perturbations and strange attractors

The asymmetrically forced, damped Duffing oscillator is introduced as a prototype model for analyzing the homoclinic tangle of symmetric dissipative systems with \textit{symmetry breaking} disturbances. Even a slight fixed asymmetry in the perturbation may cause a substantial change in the asymptotic behavior of the system, e.g. transitions from two sided to one sided strange attractors as the other parameters are varied. Moreover, slight asymmetries may cause substantial asymmetries in the relative size of the basins of attraction of the unforced nearly symmetric attracting regions. These changes seems to be associated with homoclinic bifurcations. Numerical evidence indicates that \textit{strange attractors} appear near curves corresponding to specific secondary homoclinic bifurcations. These curves are found using analytical perturbational tools

Management of bipolar depression with lamotrigine: an antiepileptic mood stabilizer

The efficacy of lamotrigine in the treatment of focal epilepsies have already been reported in several case reports and open studies, which is thought to act by inhibiting glutamate release through voltage-sensitive sodium channels blockade and neuronal membrane stabilization. However, recent findings have also illustrated the importance of lamotrigine in alleviating the depressive symptoms of bipolar disorder, without causing mood destabilization or precipitating mania. Currently, no mood stabilizers are available having equal efficacy in the treatment of both mania and depression, two of which forms the extreme sides of the bipolar disorder. Lamotrigine, a well established anticonvulsant has received regulatory approval for the treatment and prevention of bipolar depression in more than 30 countries worldwide. Lamotrigine, acts through several molecular targets and overcomes the major limitation of other conventional antidepressants by stabilizing mood from ‘below baseline’ thereby preventing switches to mania or episode acceleration, thus being effective for bipolar I disorder. Recent studies have also suggested that these observations could also be extended to patients with bipolar II disorder. Thus, lamotrigine may supposedly fulfill the unmet requirement for an effective depression mood stabilizer

Universal behaviour of entrainment due to coherent structures in turbulent shear flow

I suggest a solution to a persistent mystery in the physics of turbulent shear flows: cumulus clouds rise to towering heights, practically without entraining the ambient medium, while apparently similar turbulent jets in general lose their identity within a small distance through entrainment and mixing. From dynamical systems computations on a model chaotic vortical flow, I show that entrainment and mixing due to coherent structures depend sensitively on the relative speeds of different portions of the flow. A small change in these speeds, effected for example by heating, drastically alters the sizes of the KAM tori and the chaotic mixing region. The entrainment rate and, hence, the lifetime of a turbulent shear flow, shows a universal, non-monotone dependence on the heating.Comment: Preprint replaced in order to add the following comment: accepted for publication in Phys. Rev. Let

A retrospective interventional study for evaluation of efficacy and safety of sildenafil citrate in improving intrauterine growth restriction and oligohydramnios using ultrasound Doppler velocimetry

Background: Intrauterine growth restriction (IUGR) is one of the major reasons for neonatal morbidity and mortality. Oligohydramnios is a common finding in IUGR. In majority of these cases diminished utero-placental blood flow is observed. However, in spite of this understanding and identification of high-risk patients, the management options are limited. Sildenafil citrate, a phosphodiesterase type-5 inhibitor improves utero-placental perfusion.Methods: We present a retrospective interventional study involving 50 adult pregnant women diagnosed with early-onset IUGR (n=38) and oligohydramnios (n=12). Vaginal sildenafil citrate 25 mg t.i.d. was started from the day of diagnosis till delivery. Primary efficacy endpoints included changes in Doppler parameters i.e., amniotic fluid index (AFI), uterine artery (UA)- pulsatility index (PI), resistance index (RI) and systolic diastolic ratio (S/D ratio). Secondary endpoints included live birth, birth weight, Apgar score at birth, neonatal survival to hospital discharge and adverse maternal side effects.Results: There was a statistically significant improvement in UA-PI, RI and S/D ratios (p<0.0001) in all cases. In oligohydramnios cases, treatment showed a statistical significant increase in AFI score (2.86±1.33 cm). The mean birth weight on delivery was 2200 gm with good Apgar scores. No major adverse effects were reported by women using sildenafil citrate vaginally.Conclusions: Sildenafil citrate, by increasing utero-placental perfusion, improves uterine artery Doppler patterns, AFI, fetal weight and overall better neonatal survival rates by reducing neonatal morbidity and mortality. Sildenafil citrate may hold a promising treatment strategy for management of IUGR and oligohydramnios