Simulation and fabrication of piezoresistive membrane type MEMS strain sensors

Two piezoresistive (n-polysilicon) strain sensors on a thin Si₃N₄/SiO₂ membrane with improved sensitivity were successfully fabricated by using MEMS technology. The primary difference between the two designs was the number of strips of the polysilicon patterns. For each design, a doped n-polysilicon sensing element was patterned over a thin 3 μm Si₃N₄/SiO₂ membrane. A 1000×1000 μm² window in the silicon wafer was etched to free the thin membrane from the silicon wafer. The intent of this design was to fabricate a flexible MEMS strain sensor similar in function to a commercial metal foil strain gage. A finite element model of this geometry indicates that strains in the membrane will be higher than strains in the surrounding silicon. The values of nominal resistance of the single strip sensor and the multi-strip sensor were 4.6 and 8.6 kΩ, respectively. To evaluate thermal stability and sensing characteristics, the temperature coefficient of resistance [TCR=(ΔR/R₀)/ΔT] and the gage factor [GF=(ΔR/R₀)/] for each design were evaluated. The sensors were heated on a hot plate to measure the TCR. The sensors were embedded in a vinyl ester epoxy plate to determine the sensor sensitivity. The TCR was 7.5×10⁻⁴ and 9.5×10⁻⁴/°C for the single strip and the multi-strip pattern sensors. The gage factor was as high as 15 (bending) and 13 (tension) for the single strip sensor, and 4 (bending) and 21 (tension) for the multi-strip sensor. The sensitivity of these MEMS sensors is much higher than the sensitivity of commercial metal foil strain gages and strain gage alloys.     

Aromatic Hydrogenation Catalysis: A Review

High aromatic content in diesel fuel has been recognized both to lower the fuel quality and to contribute significantly to the formation of undesired emissions in exhaust gases [1, 2]. Because of the health hazards associated with these emissions, environmental regulations governing the composition of diesel fuels are being tightened in both Europe and the United States, leading to limitations on aromatics [3, 4].     

Complexity and computability of solutions to linear programming systems

Through key examples and constructs, exact and approximate, complexity, computability, and solution of linear programming systems are reexamined in the light of Khachian's new notion of (approximate) solution. Algorithms, basic theorems, and alternate representations are reviewed. It is shown that the Klee-Minty example hasnever been exponential for (exact) adjacent extreme point algorithms and that the Balinski-Gomory (exact) algorithm continues to be polynomial in cases where (approximate) ellipsoidal centered-cutoff algorithms (Levin, Shor, Khachian, Gacs-Lovasz) are exponential. By model approximation, both the Klee-Minty and the new J. Clausen examples are shown to be trivial (explicitly solvable) interval programming problems. A new notion of computable (approximate) solution is proposed together with ana priori regularization for linear programming systems. New polyhedral constraint contraction algorithms are proposed for approximate solution and the relevance of interval programming for good starts or exact solution is brought forth. It is concluded from all this that the imposed problem ignorance of past complexity research is deleterious to research progress on computability or efficiency of computation.This research was partly supported by Project NR047-071, ONR Contract N00014-80-C-0242, and Project NR047-021, ONR Contract N00014-75-C-0569, with the Center for Cybernetic Studies, The University of Texas at Austin.     

The effect of synchronization on the interpretation of flashing lamp displays

The question of whether all the lamps on a display indicating the same state should flash in phase with each other or independently is of interest to display designers. A randomized groups experiment was carried out to answer this question. It was found that a synchronized display was interpreted more quickly and with fewer errors than a display with independently flashing lamps.     

The effect of feedback on keying performance

The introduction of new telephone signalling systems and new technologies for telephone keypads has stimulated interest in the effect of providing electronic feedback on keying performance. An experiment using a conventional keypad is reported which shows that electronic auditory feedback had no significant effect on keying speed, accuracy or subject's opinion. A further series of experiments investigating the best type of feedback to improve performance with ‘touch’ keypads is then described. It was found that an electronic tone presented through the telephone earpiece was the best feedback.

Finally, performance with two types of touch keyphones incorporating the optimum form of feedback was compared with performance using a conventional keyphone. It was found that accuracy was significantly greater with the conventional keyphone, although performance with the touch keypads could be improved by electronically removing some of the very short spurious signalling times produced by them.     

A sensitive method for the determination of amitriptyline and nortriptyline in human plasma

The kinetics of the male gametogenesis during the pregonadal period, prespermatogenesis, and "early" spermatogenesis has been described in detail. Concerning spermatogenesis in the adult individual reference is made to the articles of Courot, Hochereau-de Reviers and Ortavant (1970) and of Clermont (1972). The comparison of female and male gametogenesis (Fig. 1) shows that the "gonia stage" (asterisks) of the female germ cells is limited to one proliferation wave only, whereas the "gonia stage" of the male germ cells consists of a first proliferation wave, comparable to that of oogonia, a preparative phase to initiate spermatogenesis, and a second proliferation wave with renewal and differentiation of the spermatogonia. Germ cells in the "gonia stage" are highly sensitive towards ionising radiation and cytostatic drugs.     

Reflected Appraisals, Academic Self-Perceptions, and Math/Science Performance During Early Adolescence.

The authors tested a model of the relations among adolescents' perceptions of parents', teachers', and classmates' support for, valuing of, and beliefs about their competence in math/science; adolescents' own academic self-perceptions concerning math/science; and their academic performance. The sample included 378 middle school students; 65% were Latino, and 21% were European American. Reflected appraisals of adults' beliefs concerning both the importance of and students' competence in math/science, as well as perceived support, predicted students' own self-perceived importance, competence, scholastic behavior, and performance in these courses. Latino students reported lower mean levels of perceived competence than did European American students (controlling for maternal education). Findings have important implications for understanding achievement socialization in ethnically diverse populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MicroRNAs as Potential Biomarkers in the Differential Diagnosis of Lipomatous Tumors and Their Mimics

Adipocytic tumors are the most common subtype of soft tissue tumors. In current clinical practice, distinguishing benign lipomas from well-differentiated liposarcomas (WDLPS), as well as dedifferentiated liposarcomas (DDLPS) from their morphologic mimics, remains a significant diagnostic challenge. This is especially so when examining small biopsy samples and without the aid of additional ancillary tests. Recognizing the important role that microRNAs (miRNAs) play in tumorigenesis and their potential utility in tumor classification, we analyzed routine clinical tissue samples of benign and malignant lipomatous tumors, as well as other sarcoma mimics, to identify distinguishing miRNA-based signatures that can aid in the differential diagnosis of these entities. We discovered a 6-miRNA signature that separated lipomas from WDLPS with high confidence (AUC of 0.963), as well as a separate 6-miRNA signature that distinguished DDLPS from their more aggressive histologic mimics (AUC of 0.740). Functional enrichment analysis unveiled possible mechanistic involvement of these predictive miRNAs in adipocytic cancer-related biological processes and pathways such as PI3K/AKT/mTOR and MAPK signaling, further supporting the relevance of these miRNAs as biomarkers for adipocytic tumors. Our results demonstrate that miRNA expression profiling may potentially be used as an adjunctive tool for the diagnosis of benign and malignant adipocytic tumors. Further validation studies are warranted.