Central Policies for Local Debt: The Case of Teacher Pensions

The recent debt crises in New York City and Cleveland, the deterioration of public infra-structures in certain of our states and larger cities, and the occasional bankruptcy of smaller pension plans suggest that not all of local finance stands on a sound fiscal base. This paper examines the trends in funding for one form of state and local government debt--teacher pensions underfundings -- and asks what a central government might do to check any unwanted growth in these liabilities. The analysis concludes (i) that this form of state-local debt is sizeable and growing, (ii) that state and local governments have an implicit pay-as-you-go bias in pension financing which encourages the growth of debt, but (iii) central government benefit and funding regulations or debt relief policies can slow, or even reverse, that growth.

The role of the ventral intraparietal area (VIP/pVIP) in parsing optic flow into visual motion caused by self-motion and visual motion produced by object-motion

Retinal image motion is a composite signal that contains information about two behaviourally significant factors: self-motion and the movement of environmental objects. It is thought that the brain separates the two relevant signals, and although multiple brain regions have been identified that respond selectively to the composite optic flow signal, which brain region(s) perform the parsing process remains unknown. Here, we present original evidence that the putative human ventral intraparietal area (pVIP), a region known to receive optic flow signals as well as independent self-motion signals from other sensory modalities, plays a critical role in the parsing process and acts to isolate object-motion. We localised pVIP using its multisensory response profile, and then tested its relative responses to simulated object-motion and self-motion stimuli; results indicated that responses were much stronger in pVIP to stimuli that specified object-motion. We report two further observations that will be significant for the future direction of research in this area; firstly, activation in pVIP was suppressed by distant stationary objects compared to the absence of objects or closer objects. Secondly, we describe several other brain regions that share with pVIP selectivity for visual object-motion over visual self-motion as well as a multisensory response

Stories

This is a work of fiction

A study on the vibration-based self-monitoring capabilities of nano-enriched composite laminated beams

This is an exploratory investigation on the self-sensing capabilities of nano-enriched glass/fibre laminates for damage detection purposes through changes in the dynamic responses, which are estimated by measuring the changes in voltage due to a dynamic strain. The deformation of the nano-enriched structure introduces changes in the resistance/voltage of the nanocomposites. The measured voltage signals contain information of the vibratory response of the laminated beam. This research uses a vibration-based data driven methodology for damage detection applied for the estimated vibratory signals using the conductivity properties of the embedded nano-particles. The structure considered in this study is a glass/fibre laminated beam enriched with carbon black nanoparticles (CB). The structure is subjected to a direct electric current and the voltage signal is measured. The vibration based monitoring method used is generally based on singular spectrum analysis applied on the estimated vibratory response. The voltage response signal is divided into a certain number of principal components which contain the oscillatory components distributed by their content of variance in the voltage signal. The components with more variance are used to define a reference state based on the status of the healthy structure. Consequently, the estimated vibratory signals from beams with a simulated damage are compared to the healthy state which eventually results in the damage detection procedure. The damage was simulated firstly by adding an additional mass on the beam tip and secondly by drilling a hole on the beam tip. The results demonstrate the potential for using the voltage estimated vibratory signals for self-sensing damage detection purposes in carbon nano-enriched glass/bre structures

Learning Written Japanese with Interactive Multimedia Assistance

The Japanese Education Ministry has funded a project, described here, to assist non-Japanese in learning to read and write Japanese. The aspects of the project which relate to the use and effectiveness of interactive multimedia are described here. The hypothesis we have been testing is that computer assistance can significantly enhance the ability to learn complex scripts such as Japanese. Even for native Japanese to learn the writing system takes about a decade, and non native adult learners report this being a major problem area. To test this hypothesis software has been built that allows students and teachers to interact electronically using proprietary multimedia enhanced email. Whilst such communication takes place, we record quantitative aspects of the interactions. Questionnaires have provided qualitative feedback. Any language learner needs considerable context in which to situate their learning. Multimedia can provide context, and interactivity allows a more active learning role to be taken. By adding these elements to the immediacy and cost effectiveness of electronic communication, we believe the language learner can derive considerable benefit. The system is described here, together with some results of our trials

Multi-variate coding for possession: methodology and preliminary results

In this work we are presenting a database structure to encode the phenomenon of differential possession across languages, considering noun possession classes and possessive constructions as independent but linked. We show how this structure can be used to study different dimensions of possession: semantics, noun valence, and possessive constructions. We present preliminary survey results from a global sample of 120 languages and show that there is a universal semantic core in both inalienable and non-possessible noun classes. Inalienables are centered on body parts and kinship. Non-possessibles are centered on animals, humans, and natural elements

The Effect of Impingement on Transitional Behavior in Underexpanded Jets

An investigation into the development of flow unsteadiness in impinging axisymmetric underexpanded jets has been conducted at NASA Langley Research Center. The study has examined the effect of an impingement target placed at various distances and angles on transitional behavior of such jets. Two nozzles, with exit Mach numbers of 1.0 and 2.6, were used in this investigation. Planar laser-induced fluorescence of nitric oxide (NO PLIF) has been used to identify flow unsteadiness and to image transitional and turbulent flow features. Measurements of the location of the onset of various degrees of unsteady flow behavior have been made using these PLIF images. Both qualitative and quantitative comparisons are presented to demonstrate the observed effects of impingement and flow parameters on the process of the transition to turbulence. The presence of the impingement target was found to significantly shorten the distance to transition to turbulence by up to a factor of approximately three, with closer targets resulting in slightly shorter distance to transition and turbulence. The location at which the flow first exhibits unsteadiness was found to have a strong dependence on the presence and location of key flow structures. This paper presents quantitative results on transition criteria for free and impinging jets

Identification of Instability Modes of Transition in Underexpanded Jets

A series of experiments into the behavior of underexpanded jet flows has been conducted at NASA Langley Research Center. Two nozzles supplied with high-pressure gas were used to generate axisymmetric underexpanded jets exhausting into a low-pressure chamber. These nozzles had exit Mach numbers of 1 and 2.6, though this paper will present cases involving only the supersonic nozzle. Reynolds numbers based on nozzle exit conditions ranged from about 300 to 22,000, and nozzle exit-to-ambient jet pressure ratios ranged from about 1 to 25. For the majority of cases, the jet fluid was a mixture of 99.5% nitrogen seeded with 0.5% nitric oxide (NO). Planar laser-induced fluorescence (PLIF) of NO is used to visualize the flow, visualizing planar slices of the flow rather than path integrated measurements. In addition to revealing the size and location of flow structures, PLIF images were also used to identify unsteady jet behavior in order to quantify the conditions governing the transition to turbulent flow. Flow structures that contribute to the growth of flow instabilities have been identified, and relationships between Reynolds number and transition location are presented. By highlighting deviations from mean flow properties, PLIF images are shown to aide in the identification and characterization of flow instabilities and the resulting process of transition to turbulence