Neutral winds in the lower thermosphere from Dynamics Explorer 2

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95275/1/grl6105.pd

One-Step Approach to Single-Ensemble CdS Magic-Size Clusters with Enhanced Production Yields

We report on the development of a single-step method for synthesizing colloidal semiconductor magic-size clusters (MSCs) with an enhanced production yield in a single-ensemble form and free of the coproduction of conventional quantum dots (QDs). This process eliminates the need for the second step of a lower-temperature incubation used in a two-step approach reported recently for the fabrication of single-ensemble MSCs without QD contamination. We demonstrate that the combined use of a secondary phosphine (HPR₂) and an α-methyl carboxylic acid [RCH­(CH₃)-COOH, MA] promotes the yield of MSCs and suppresses the nucleation and growth of QDs. With CdO and elemental S powder as Cd and S sources, respectively, a single ensemble of CdS MSC-311 (displaying a sharp absorption peak at 311 nm) evolves directly in a reaction in 1-octadecene with an enhanced production yield. This study introduces a one-step avenue for synthesizing effectively and selectively single-ensemble MSCs and improves our understanding of the two-pathway model proposed for the prenucleation stage of QDs

Non-Linear Neuronal Responses as an Emergent Property of Afferent Networks: A Case Study of the Locust Lobula Giant Movement Detector

In principle it appears advantageous for single neurons to perform non-linear operations. Indeed it has been reported that some neurons show signatures of such operations in their electrophysiological response. A particular case in point is the Lobula Giant Movement Detector (LGMD) neuron of the locust, which is reported to locally perform a functional multiplication. Given the wide ramifications of this suggestion with respect to our understanding of neuronal computations, it is essential that this interpretation of the LGMD as a local multiplication unit is thoroughly tested. Here we evaluate an alternative model that tests the hypothesis that the non-linear responses of the LGMD neuron emerge from the interactions of many neurons in the opto-motor processing structure of the locust. We show, by exposing our model to standard LGMD stimulation protocols, that the properties of the LGMD that were seen as a hallmark of local non-linear operations can be explained as emerging from the dynamics of the pre-synaptic network. Moreover, we demonstrate that these properties strongly depend on the details of the synaptic projections from the medulla to the LGMD. From these observations we deduce a number of testable predictions. To assess the real-time properties of our model we applied it to a high-speed robot. These robot results show that our model of the locust opto-motor system is able to reliably stabilize the movement trajectory of the robot and can robustly support collision avoidance. In addition, these behavioural experiments suggest that the emergent non-linear responses of the LGMD neuron enhance the system's collision detection acuity. We show how all reported properties of this neuron are consistently reproduced by this alternative model, and how they emerge from the overall opto-motor processing structure of the locust. Hence, our results propose an alternative view on neuronal computation that emphasizes the network properties as opposed to the local transformations that can be performed by single neurons

An Improvement in water resources management in Dagupan City using system dynamics

Dagupan City is the business and commercial center of Pangasinan. At present, the only source of water for the people of Dagupan is from underground reservoirs extracted daily in huge amount thru massive deep wells scattered all over the city. In other words, the city has no existing surface water treatment plant and no dam to service its water requirements unlike Metro Manila or Cebu. Groundwater is not an inexhaustible source of water supply. Though it is rechargeable, water extraction on a colossal scale over a period of time would have the dire consequences of pore pressure reduction, weaken underground structure and salt intrusion which in turn will result to sinking ground surface, higher costs of building construction and greater devastation in case of an earthquake. The objective of this study therefore is to understand the behavior of the whole water system affecting the sustainability of the groundwater supply. All the data needed for this study were obtained from the Dagupan City Water District (DCWD), and the Dagupan City Hall. Using System Dynamics Analysis (SDA), the behavior of the system was able to be simulated. Subsequently, after coming out with possible scenarios and alternatives a preferred path of steps and solutions is proposed such as increase in water rates, a water treatment plant, availment of foreign loans having concessional rates with a grace period, water conservation measures, among other things in order to prolong and preserve the life of the groundwater supply

Earthquake Disaster Resilience: A Framework for Sustainable Gardening in Haiti’s Vulnerable Population.

Food shortages following earthquake disasters lead to chronic food insecurity, malnutrition, illness, and an escalation in deaths. For Haiti, an island nation with limited resources, including food, resilience is more difficult without a framework to guide recovery. A model that proposes the use of partnership development and gardening interventions to achieve sustainable food relief is described. The approach involves assessment of needs, nutrition education and training, community and home gardens, partnerships, entrepreneurship, policy development, marketing, and the involvement of stakeholders in local and international communities. Application of the model may greatly enhance sustainable food supply for the most vulnerable populations in Haiti