From memory to processing : a reaction-diffusion approach to neuromorphic computing

The goal of this research is to bridge the gap between the physiological brain and mathematically based neuromorphic computing models. As such, the reaction-diffusion method was chosen as it can naturally exhibit properties like propagation of excitation that are seen in the brain, but not current neuromorphic computing models. A reaction-diffusion memory unit was created to demonstrate the key memory functions of sensitization, habituation, and dishabituation, while a reaction-diffusion brain module was established to perform the specific processing task of single-digit binary addition. The results from both approaches were consistent with existing literature detailing physiological memory and processing in the human brain

Reaction-diffusion memory unit: Modeling of sensitization, habituation and dishabituation in the brain.

We propose a novel approach to investigate the effects of sensitization, habituation and dishabituation in the brain using the analysis of the reaction-diffusion memory unit (RDMU). This unit consists of Morris-Lecar-type sensory, motor, interneuron and two input excitable cables, linked by four synapses with adjustable strength defined by Hebbian rules. Stimulation of the sensory neuron through the first input cable causes sensitization by activating two excitatory synapses, C1 and C2, connected to the interneuron and motor neuron, respectively. In turn, the stimulation of the interneuron causes habituation through the activation of inhibitory synapse C3. Likewise, dishabituation is caused through the activation of another inhibitory synapse C4. We have determined sensitization-habituation (BSH) and habituation-dishabituation (BHDH) boundaries as functions between synaptic strengths C2 and C3 at various strengths of C1 and C4. When BSH and BHDH curves shift towards larger values of C2, the RDMU can be easily inhibited. On the contrary, the RDMU can be easily sensitized or dishabituated if BSH and BHDH curves shift towards smaller values of C2. Our numerical simulations readily demonstrate that higher values of the Morris-Lecar relaxation parameter, greater leakage and potassium conductances, reduced length of the interneuron, and higher values of C1 all result in easier habituation of the RDMU. In contrast, we found that at higher values of C4 the RDMU becomes significantly more prone to dishabituation. Based on these simulations one can quantify BSH and BHDH curve shifts and relate them to particular neural outcomes

Separation System for Tethered Satellites

Capstone Design and Manufacturing Experience: Winter 2006The success of the TSATT mission is dependent on a successful tether deployment: a flawless separation without tangling due to interference with the separation system. Separation system benchmarks have been researched to help guide our design and establish a foundation for the separation concept. The ideal heritage-flown separation system called the Lightband is not feasible to separate our two payloads due to the cost exceeding $110,000 and possible tether snag issues. The goal for our ME 450 team is to prove that our laboratory can design, fabricate, and test a separation system that can be integrated for separating the two payloads during the TSATT mission.http://deepblue.lib.umich.edu/bitstream/2027.42/49578/2/proj21_report.pd

Everolimus in Neuroendocrine Tumors of the Gastrointestinal Tract and Unknown Primary

&lt;b&gt;&lt;i&gt;Purpose:&lt;/i&gt;&lt;/b&gt; The RADIANT-4 randomized phase 3 study demonstrated significant prolongation of median progression-free survival (PFS) with everolimus compared to placebo (11.0 [95% CI 9.2-13.3] vs. 3.9 [95% CI 3.6-7.4] months) in patients with advanced, progressive, nonfunctional gastrointestinal (GI) and lung neuroendocrine tumors (NET). This analysis specifically evaluated NET patients with GI and unknown primary origin. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; Patients in the RADIANT-4 trial were randomized 2:1 to everolimus 10 mg/day or placebo. The effect of everolimus on PFS was evaluated in patients with NET of the GI tract or unknown primary site. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; Of the 302 patients enrolled, 175 had GI NET (everolimus, 118; placebo, 57) and 36 had unknown primary (everolimus, 23; placebo, 13). In the GI subset, the median PFS by central review was 13.1 months (95% CI 9.2-17.3) in the everolimus arm versus 5.4 months (95% CI 3.6-9.3) in the placebo arm; the hazard ratio (HR) was 0.56 (95% CI 0.37-0.84). In the unknown primary patients, the median PFS was 13.6 months (95% CI 4.1-not evaluable) for everolimus versus 7.5 months (95% CI 1.9-18.5) for placebo; the HR was 0.60 (95% CI 0.24-1.51). Everolimus efficacy was also demonstrated in both midgut and non-midgut populations; a 40-46% reduction in the risk of progression or death was reported for patients in the combined GI and unknown primary subgroup. Everolimus had a benefit regardless of prior somatostatin analog therapy. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; Everolimus showed a clinically meaningful PFS benefit in patients with advanced progressive nonfunctional NET of GI and unknown primary, consistent with the overall RADIANT-4 results, providing an effective new standard treatment option in this patient population and filling an unmet treatment need for these patients.</jats:p