Older Canadian homeowners : a literature review

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The Portfolio Pension Plan: An Alternative Model for Retirement Security

This chapter describes a proposed new defined benefit (DB) pension design known as a portfolio pension plan. This design falls within a larger category of so-called ‘shared risk’ pension plans. In the United States, shared risk pension plans address a need created by the limitations of existing retirement plan designs. An alternative to existing designs is needed because DB plans to date have concentrated risk on plan sponsors in a way that makes them financially unsustainable in many, if not most, circumstances. Moreover, existing defined contribution (DC) retirement plans impose risk on employees in a way that is challenging for most individuals to manage. In the past, many employers shared risk with employees by providing both a DB and a DC plan. Nevertheless, this chapter argues that a new model can provide an alternative that better serves employers and employees in the United States

Upward synaptic scaling is dependent on neurotransmission rather than spiking

Homeostatic plasticity encompasses a set of mechanisms that are thought to stabilize firing rates in neural circuits. The most widely studied form of homeostatic plasticity is upward synaptic scaling (upscaling), characterized by a multiplicative increase in the strength of excitatory synaptic inputs to a neuron as a compensatory response to chronic reductions in firing rate. While reduced spiking is thought to trigger upscaling, an alternative possibility is that reduced glutamatergic transmission generates this plasticity directly. However, spiking and neurotransmission are tightly coupled, so it has been difficult to determine their independent roles in the scaling process. Here we combined chronic multielectrode recording, closed-loop optogenetic stimulation, and pharmacology to show that reduced glutamatergic transmission directly triggers cell-wide synaptic upscaling. This work highlights the importance of synaptic activity in initiating signalling cascades that mediate upscaling. Moreover, our findings challenge the prevailing view that upscaling functions to homeostatically stabilize firing rates.National Science Foundation (U.S.). Graduate Research Fellowship (09-603)National Science Foundation (U.S.). Graduate Research Fellowship (08-593)National Science Foundation (U.S.). Integrative Graduate Education and Research Traineeship (Fellowship DGE-0333411)Emory University (NI SPINR Fellowship

The Effect of Sensory Blind Zones on Milling Behavior in a Dynamic Self-Propelled Particle Model

Emergent pattern formation in self-propelled particle (SPP) systems is extensively studied because it addresses a range of swarming phenomena which occur without leadership. Here we present a dynamic SPP model in which a sensory blind zone is introduced into each particle's zone of interaction. Using numerical simulations we discovered that the degradation of milling patterns with increasing blind zone ranges undergoes two distinct transitions, including a new, spatially nonhomogeneous transition that involves cessation of particles' motion caused by broken symmetries in their interaction fields. Our results also show the necessity of nearly complete panoramic sensory ability for milling behavior to emerge in dynamic SPP models, suggesting a possible relationship between collective behavior and sensory systems of biological organisms.Comment: 12 pages, 4 figure

Real-time in vivo optogenetic neuromodulation and multielectrode electrophysiologic recording with NeuroRighter

Optogenetic channels have greatly expanded neuroscience’s experimental capabilities, enabling precise genetic targeting and manipulation of neuron subpopulations in awake and behaving animals. However, many barriers to entry remain for this technology – including low-cost and effective hardware for combined optical stimulation and electrophysiologic recording. To address this, we adapted the open-source NeuroRighter multichannel electrophysiology platform for use in awake and behaving rodents in both open and closed-loop stimulation experiments. Here, we present these cost-effective adaptations, including commercially available LED light sources; custom-made optical ferrules; 3D printed ferrule hardware and software to calibrate and standardize output intensity; and modifications to commercially available electrode arrays enabling stimulation proximally and distally to the recording target. We then demonstrate the capabilities and versatility of these adaptations in several open and closed-loop experiments, demonstrate spectrographic methods of analyzing the results, as well as discuss artifacts of stimulation.Emory University. School of Medicine (Emory Neurosciences Initiative seed grant)American Epilepsy SocietyEpilepsy Foundation of America (Predoctoral fellowship)National Science Foundation (U.S.) (NSF GRFP Fellowship 08-593)National Science Foundation (U.S.) (NSF IGERT Fellowship DGE-0333411)National Science Foundation (U.S.) (NSF EFRI #1238097)National Institutes of Health (U.S.) (NIH 1R01NS079757-01)American Society for Engineering Education (SMART Fellowship

A self-consistent approach to measure preferential attachment in networks and its application to an inherent structure network

Preferential attachment is one possible way to obtain a scale-free network. We develop a self-consistent method to determine whether preferential attachment occurs during the growth of a network, and to extract the preferential attachment rule using time-dependent data. Model networks are grown with known preferential attachment rules to test the method, which is seen to be robust. The method is then applied to a scale-free inherent structure network, which represents the connections between minima via transition states on a potential energy landscape. Even though this network is static, we can examine the growth of the network as a function of a threshold energy (rather than time), where only those transition states with energies lower than the threshold energy contribute to the network.For these networks we are able to detect the presence of preferential attachment, and this helps to explain the ubiquity of funnels on energy landscapes. However, the scale-free degree distribution shows some differences from that of a model network grown using the obtained preferential attachment rules, implying that other factors are also important in the growth process.Comment: 8 pages, 8 figure

Mapping the Association of Global Executive Functioning Onto Diverse Measures of Psychopathic Traits

Psychopathic individuals display a callous-coldhearted approach to interpersonal and affective situations and engage in impulsive and antisocial behaviors. Despite early conceptualizations suggesting that psychopathy is related to enhanced cognitive functioning, research examining executive functioning (EF) in psychopathy has yielded few such findings. It is possible that some psychopathic trait dimensions are more related to EF than others. Research using a 2-factor or 4-facet model of psychopathy highlights some dimension-specific differences in EF, but this research is limited in scope. Another complicating factor in teasing apart the EF–psychopathy relationship is the tendency to use different psychopathy assessments for incarcerated versus community samples. In this study, an EF battery and multiple measures of psychopathic dimensions were administered to a sample of male prisoners (N