Polycrystalline silicon thermal actuators integrated with photodiode

A thermal actuator (TA) is the thermal compliment of electrostatic actuators. A TA has several advantages over other microactuation methods. They can provide relatively large forces (^N) and large displacements (\u3e10 jam) at CMOS compatible voltages and currents. The main disadvantage of a TA is it large power consumption. A TA can be used in basic building-block MEM devices such as stepper motors, optical-component positioners, and grippers. The TA shown below in Figure 36 converts electrical energy into mechanical via ohmic heating and deflects due to asymmetric heating. The disparity in the widths of the Cold (wide) beam and the Hot (thin) beam causes an uneven current density to flow through the TA when an electrical bias is placed across the ends of the two beams. The higher current density in the Hot beam causes it to expand, due to thermal expansion, more than the Cold beam. This results in the sweeping of an arc in the plane of the wafer by the free end of the TA. Figure 37 shows a TA in its electrically biased state. Figure 36: Thermal actuator in the steady-state position. Figure 37: Thermal actuator in biased state. I propose to design, develop a fabrication process, fabricate, and test microsystems that integrate a polycrystalline silicon TA with a photodetector. The microsystem uses a photodetector as a position sensor to indicate the TA position in real-time. The process flow simulation will be accomplished using Silvaco Athena Process Simulator as a part of the design process. Various polycrystalline silicon TA will be fabricated in order to verify the effects of the design parameters. The design parameters are the length and width of the Hot Arm. The chip design will incorporate test structures to aid in the analysis of the structures and photodiodes and will use the Mentor Graphics IC layout editor. The design will not incorporate on-chip signal amplification. The fabrication process used will incorporate standard integrated circuit technologies, processes and standard surface micromachining processes. Optical and Scanning Electron Microscope photographs of the devices will be taken after important processing steps. Tests will include actuator position determination via photodetector current, maximum deflection, photodiode current-voltage characteristics, and TA cyclic fatigue. Video of the electrical testing will be taken. An empirical model of the relationship between the deflection and the current will be developed

Democracia, duración del régimen, y recimiento

Findings of regularities in statistical relationships between regime type and economic growth are debatable, because specifications are variable. We argue that the effect of regime type on growth is contingent on the duration of the regime. Further, the effect of duration depends on regime type: older autocracies grow at a different rate than older democracies. The reason is that the causes for decelerating growth are fundamentally different in democracies and autocracies. Our estimations are run on a large (unbalanced) annual panel of 155 countries from 1950 – 2006. In this sample, autocracies grew around 0.75 percentage points more slowly than non-autocracies, holding constant the regime-specific effect of regime duration. Autocratic growth rises for the first 30 years, after which growth rates fall rapidly. Non-autocracies always grow faster than equally old autocracies, but the differences are especially pronounced when young and old regimes are compared. Some implications of this result for the political system of Brazil are discussed.Os achados de regularidades nas relações estatísticas entre o tipo de regime e o crescimento econômico são discutíveis, porque as especificações são variáveis. Argumentamos que o efeito do tipo de regime sobre o crescimento depende da duração do regime. Além disso, o efeito da duração depende do tipo de regime: as autocracias mais antigas crescem a uma taxa diferente das democracias mais antigas. A razão é que as causas da desaceleração do crescimento são fundamentalmente diferentes nas democracias e autocracias. Nossas estimativas são feitas com um painel anual (desbalanceado) de 155 países de 1950 a 2006. Nesta amostra, as autocracias cresceram cerca de 0,75 pontos percentuais mais lentamente do que as não-autocracias, mantendo constante o efeito específico do regime da duração do regime. O crescimento nas autocracias aumenta nos primeiros 30 anos, após os quais as taxas de crescimento caem rapidamente. As não-autocracias sempre crescem mais rápido do que as autocracias igualmente antigas, mas as diferenças são especialmente pronunciadas quando os regimes jovens e velhos são comparados. Algumas implicações desse resultado para o sistema político do Brasil são discutidas.Los hallazgos de regularidades en las relaciones estadísticas entre el tipo de régimen y el crecimiento económico son discutibles, porque las especificaciones son variables. Argumentamos que el efecto del tipo de régimen sobre el crecimiento depende de la duración del régimen. Además, el efecto de la duración depende del tipo de régimen: las autocracias más antiguas crecen a un ritmo diferente al de las democracias más antiguas. La razón es que las causas de la desaceleración del crecimiento son fundamentalmente diferentes en las democracias y las autocracias. Nuestras estimaciones se ejecutan en un panel anual grande (no equilibrado) de 155 países entre 1950 y 2006. En esta muestra, las autocracias crecieron alrededor de 0,75 puntos porcentuales más lentamente que las no autocracias, manteniendo constante el efecto específico del régimen de la duración del régimen. El crecimiento autocrático aumenta durante los primeros 30 años, después de lo cual las tasas de crecimiento caen rápidamente. Las no autocracias siempre crecen más rápido que las autocracias igualmente antiguas, pero las diferencias son especialmente pronunciadas cuando regímenes jóvenes y viejos son comparados. Se discuten algunas implicaciones de este resultado para el sistema político de Brasil.Revista do Serviço Público - RSP, v. 72 n. edição especial, 12-40 p.EconomiaGestão PúblicaLiderançaISSN Impresso: 0034-9240ISSN Eletrônico: 2357-801

An olfactory subsystem that detects carbon disulfide and mediates food-related social learning

In mammals, pheromones and other social cues can promote mating or aggression behaviors; can communicate information about social hierarchies, genetic identity and health status; and can contribute to associative learning. However, the molecular, cellular, and neural mechanisms underlying many olfactory-mediated social interactions remain poorly understood. Here, we show a specialized olfactory subsystem that includes olfactory sensory neurons (OSNs) expressing the receptor guanylyl cyclase GC-D, the cyclic nucleotide-gated channel subunit CNGA3, and the carbonic anhydrase isoform CAII (GC-D(+) OSNs) is required for the acquisition of socially transmitted food preferences (STFPs) in mice

Measuring and explaining political sophistication through textual complexity

Political scientists lack domain-specific measures for the purpose of measuring the sophistication of political communication. We systematically review the shortcomings of existing approaches, before developing a new and better method along with software tools to apply it. We use crowdsourcing to perform thousands of pairwise comparisons of text snippets and incorporate these results into a statistical model of sophistication. This includes previously excluded features such as parts of speech and a measure of word rarity derived from dynamic term frequencies in the Google books dataset. Our technique not only shows which features are appropriate to the political domain and how, but also provides a measure easily applied and re-scaled to political texts in a way that facilitates probabilistic comparisons. We reanalyze the State of the Union corpus to demonstrate how conclusions differ when using our improved approach, including the ability to compare complexity as a function of covariates

Interannual variability in ozone removal by a temperate deciduous forest

The ozone (O3) dry depositional sink and its contribution to observed variability in tropospheric O3 are both poorly understood. Distinguishing O3 uptake through plant stomata versus other pathways is relevant for quantifying the O3 influence on carbon and water cycles. We use a decade of O3, carbon, and energy eddy covariance (EC) fluxes at Harvard Forest to investigate interannual variability (IAV) in O3 deposition velocities ( math formula). In each month, monthly mean math formula for the highest year is twice that for the lowest. Two independent stomatal conductance estimates, based on either water vapor EC or gross primary productivity, vary little from year to year relative to canopy conductance. We conclude that nonstomatal deposition controls the substantial observed IAV in summertime math formula during the 1990s over this deciduous forest. The absence of obvious relationships between meteorology and math formula implies a need for additional long-term, high-quality measurements and further investigation of nonstomatal mechanisms

Terrestrial biosphere models need better representation of vegetation phenology: results from the North American Carbon Program Site Synthesis

Phenology, by controlling the seasonal activity of vegetation on the land surface, plays a fundamental role in regulating photosynthesis and other ecosystem processes, as well as competitive interactions and feedbacks to the climate system. We conducted an analysis to evaluate the representation of phenology, and the associated seasonality of ecosystem-scale CO2 exchange, in 14 models participating in the North American Carbon Program Site Synthesis. Model predictions were evaluated using long-term measurements (emphasizing the period 2000-2006) from 10 forested sites within the AmeriFlux and Fluxnet-Canada networks. In deciduous forests, almost all models consistently predicted that the growing season started earlier, and ended later, than was actually observed; biases of 2 weeks or more were typical. For these sites, most models were also unable to explain more than a small fraction of the observed interannual variability in phenological transition dates. Finally, for deciduous forests, misrepresentation of the seasonal cycle resulted in over-prediction of gross ecosystem photosynthesis by +160 ± 145 g C m-2 y-1 during the spring transition period, and +75 ± 130 g C m-2 y-1 during the autumn transition period (13% and 8% annual productivity, respectively) compensating for the tendency of most models to under-predict the magnitude of peak summertime photosynthetic rates. Models did a better job of predicting the seasonality of CO2 exchange for evergreen forests. These results highlight the need for improved understanding of the environmental controls on vegetation phenology, and incorporation of this knowledge into better phenological models. Existing models are unlikely to predict future responses of phenology to climate change accurately, and therefore will misrepresent the seasonality and interannual variability of key biosphere-atmosphere feedbacks and interactions in coupled global climate models.Engineering and Applied SciencesOrganismic and Evolutionary Biolog

Senior Recital

Program listing performers and works performe

Master\u27s Recital

List of performers and performances

Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer's disease

We identified rare coding variants associated with Alzheimer’s disease (AD) in a 3-stage case-control study of 85,133 subjects. In stage 1, 34,174 samples were genotyped using a whole-exome microarray. In stage 2, we tested associated variants (P<1×10-4) in 35,962 independent samples using de novo genotyping and imputed genotypes. In stage 3, an additional 14,997 samples were used to test the most significant stage 2 associations (P<5×10-8) using imputed genotypes. We observed 3 novel genome-wide significant (GWS) AD associated non-synonymous variants; a protective variant in PLCG2 (rs72824905/p.P522R, P=5.38×10-10, OR=0.68, MAFcases=0.0059, MAFcontrols=0.0093), a risk variant in ABI3 (rs616338/p.S209F, P=4.56×10-10, OR=1.43, MAFcases=0.011, MAFcontrols=0.008), and a novel GWS variant in TREM2 (rs143332484/p.R62H, P=1.55×10-14, OR=1.67, MAFcases=0.0143, MAFcontrols=0.0089), a known AD susceptibility gene. These protein-coding changes are in genes highly expressed in microglia and highlight an immune-related protein-protein interaction network enriched for previously identified AD risk genes. These genetic findings provide additional evidence that the microglia-mediated innate immune response contributes directly to AD development