A low-voltage three-axis electromagnetically actuated micromirror for fine alignment among optical devices

In this paper, a new three-axis electromagnetically actuated micromirror structure has been proposed and fabricated. It is electromagnetically actuated at low voltage using an external magnetic field. The main purpose of this work was to obtain a three-axis actuated micromirror in a mechanically robust structure with large static angular and vertical displacement at low actuation voltage for fine alignment among optical components in an active alignment module as well as conventional optical systems. The mirror plate and torsion bars are made of bulk silicon using a SOI wafer, and the actuation coils are made of electroplated Au. The maximum static deflection angles were measured as +/-4.2 for x -axis actuation and +/-.2 for y -axis actuation, respectively. The maximum static vertical displacement was measured as +/-42 um for z -axis actuation. The actuation voltages were below 3 V for all actuation. The simulated resonant frequencies are several kHz, and these imply that the fabricated micromirror can be operated in sub-millisecond order. The measured radius of curvature (ROC) of the fabricated micromirror is 7.72 cm, and the surface roughness of the reflector is below 1.29 nm which ensure high optical performance such as high directionality and reflectivity. The fabricated micromirror has demonstrated large actuated displacement at low actuation voltage, and it enables us to compensate a larger misalignment value when it is used in an active alignment module. The robust torsion bar and lifting bar structure formed by bulk silicon allowed the proposed micromirror to have greater operating stability. The additional degree of freedom with z -axis actuation can decrease the difficulty in the assembly of optical components and increase the coupling efficiency between optical components.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65102/2/jmm9_8_085007.pd

Design and fabrication of a single membrane push-pull SPDT RF MEMS switch operated by electromagnetic actuation and electrostatic hold

In this paper, we report a new push-pull-type SPDT (single pole double throw) switch actuated by the combination of electromagnetic and electrostatic forces for low power and low voltage operation. The switch is initially actuated by large electromagnetic force to change its state and is held to maintain its state by applying electrostatic force to reduce static power consumption. The electromagnetic force can be easily generated at low voltage. The maximum actuation voltage is below 4.3 V and the required energy is 15.4 µJ per switching. It achieves signal isolation of −54 dB and insertion loss of −0.16 dB at 2 GHz, respectively. For 20 GHz operation, isolation and insertion loss were measured as −36 dB and −0.52 dB, respectively. The proposed SPDT switch combines two switching elements in a single structure, simplifying the overall structure and control signals and eliminating mismatches between the two switching elements. The dimension of the switch has been optimized using FEM simulation and analytical calculations. We have successfully carried out a lifetime test over more than 166 million cycles with the maximum actuation voltage below 4.3 V.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85424/1/jmm10_3_035028.pd

Case of chronic indolent pheochromocytoma that caused medically controlled hypertension but treatment-resistant diabetes mellitus

No abstract available

The Relationship between Metacognition, Entrepreneurial Orientation, and Firm Performance: An Empirical Investigation

This study aims to examine the relationship between an entrepreneur’s metacognition, entrepreneurial orientation (EO), and firm performance. We collected primary data from 190 entrepreneurs (business owners or founders) working in the U.S. through a survey. By performing both the confirmatory factor analysis (CFA) and the structural equation modeling (SEM), we tested our hypothesized research model that represented the metacognition-EO-firm performance relationship. The results from the statistical analysis demonstrate that an entrepreneur\u27s metacognition has a significant positive impact on EO. Furthermore, the study result shows that EO has a full mediating effect on the relationship between entrepreneurial metacognition and firm performance. We, thus, anticipate that the findings of this study will help entrepreneurs to understand the mechanism on how their metacognitions impact their business outcomes as well as to recognize why they should consider their metacognitive abilities while executing entrepreneurial tasks

Blue Ocean Strategy vs. Competitive Strategy: The Effect of Business Strategic Choices on Firm Performance, According to the Industry Life Cycle

The purpose of this study is to explore how blue ocean strategy and competitive strategy influence a firm\u27s business performance differently according to its stage in the industry life cycle (ILC). We developed a theoretical research model and the measure items to capture the different attributes of the blue ocean and competitive paradigms. We collected primary data from 309 business owners and senior managers working in the U.S. through a survey research. We tested the data by performing the exploratory factor analysis (EFA), the confirmatory factor analysis (CFA) and the structural equation modeling analysis (SEM) using SPSS and AMOS. The results from the statistical analysis demonstrate that the effects of blue ocean strategy on a firm\u27s business performance become increasingly weak as ILC stages pass, while the effects of competitive strategy gradually strengthen. However, our results show that, in general, blue ocean strategy has a more positive effect on a firm\u27s performance than competitive strategy. In addition, the study results suggest that blue ocean strategy fully mediates the relationship between a firm\u27s market orientation and its business performance, while competitive strategy only partially mediates the relationship. We discuss some theoretical implications and contributions of our research findings

Cerebrovascular Atherosclerosis: Cognitive Dysfunction Progress and Autophagic Regression

As the aging of society, metabolic disorders have become a major concern and a major cause for cardio- and neurovascular diseases such as atherosclerosis, stroke, and even cognitive decline. This chapter shows the progressive plaque formation mechanisms and regression under autophagic flow in both experimental and clinical side. Atherosclerotic plaque formation is not irrevocable. Clinical and experimental reports accept that atherosclerosis can regress after statin treatment. This chapter focuses on autophagic roles in atherosclerotic plaque formation, progression, and regression. Another focus is on the relationship between atherosclerosis and an increased risk of cognitive decline and further conversion from mild cognitive impairment (MCI) to dementia. There has been broad and strong support on the relationship between atherosclerotic severity and cognitive function. Ultrasound findings such as intima-media thickness (IMT) and plaque numbers could potentially be useful in identifying individuals with a higher risk of progression from cognitive decline according to morphological criteria. This also suggests the possibility as a predictive indicator of MCI and dementia by considering the presence of atherosclerotic changes. Focusing on therapeutics, this chapter provides mechanisms for regressing atherosclerotic plaques. Autophagy suggests therapeutic possibilities for atherosclerosis and it consequently paves the way for preventing cognitive impairment