Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Population. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

High-resolution reversible folding of hyperstable RNA tetraloops using molecular dynamics simulations

Abstract: We report the de novo folding of three hyperstable RNA tetraloops to 1–3 A rmsd from their experimentally determined structures using molecular dynamics simulations initialized in the unfolded state. RNA tetraloops with loop sequences UUCG, GCAA, or CUUG are hyperstable because of the formation of noncanonical loop-stabilizing interactions, and they are all faithfully reproduced to angstrom-level accuracy in replica exchange molecular dynamics simulations, including explicit solvent and ion molecules. This accuracy is accomplished using unique RNA parameters, in which biases that favor rigid, highly stacked conformations are corrected to accurately capture the inherent flexibility of ssRNA loops, accurate base stacking energetics, and purine syn-anti interconversions. In a departure from traditional quantum chemistrycentric approaches to force field optimization, our parameters are calibrated directly from thermodynamic and kinetic measurements of intra- and internucleotide structural transitions. The ability to recapitulate the signature noncanonical interactions of the three most abundant hyperstable stem loop motifs represents a significant milestone to the accurate prediction of RNA tertiary structure using unbiased all-atom molecular dynamics simulations.

Copper metallization for ULSL and beyond

Abstract: The investigation of copper for use as an interconnection metal in the ultra large-scale integration (ULSI) era of silicon integrated circuits has accelerated in the past several years. The obvious advantages for using copper to replace currently used Al are related to its lower resistivity (1.7 μΩ-cm vs. 2.7 μω-cm for Al) and its higher electromigration resistance (several orders of magnitude higher compared with Al). The goal of this review is to examine the properties of copper and its applicability as the interconnection metal. A comparison of electromigration behavior of various possible interconnection metal in standard “bulk” state is made. This is followed by a review of the calculations made comparing (a) the RC (resistance × capacitance) time constants of various material systems and (b) the joule heating of the interconnection materials. A comparative study of various metal systems for the application as the interconnect metal is then made. These discussions will clearly establish the ...

The paralanguage of caregiving: Baby talk to the institutionalized aged.

Abstract: A field study was conducted at a nursing home to (a) obtain descriptive information on the speech environment of the institutionalized elderly and (b) provide speech samples with which to conduct judgment studies on the paralinguistic features of caregiver communication. Three kinds of speech were differentiated: baby talk, speech to the elderly that was not in baby talk, and speech between caregivers, which was assumed to be normal adult speech. Over 22% of the sentences were reliably categorized as baby talk speech. Caregivers' ratings of the characteristics of the care receivers did not predict the amount of baby talk that was directed toward individual care receivers. In Judgment Study 1, content-filtered baby talk was identified as speech to children regardless of the actual status, adult or child, of the target. In Judgment Study 2, content-filtered speech samples were rated on four dimensions: comfort, pleasantness, irritation, and arousal. Baby talk was rated positive, adult speech received intermediate ratings, and non-baby-talk was rated negative. The findings suggest that baby talk is a speech register conveying affection, and it is proposed that non-baby-talk to the elderly is an "institutional" register denoting and promoting dependency.

GaN based transistors for high power applications

Abstract: Unique properties of GaN and related semiconductors make them superior for high-power applications. The maximum density of the two-dimensional electron gas at the GaN/AlGaN heterointerface or in GaN/AlGaN quantum well structures can exceed 2×1013 cm−2, which is more than an order of magnitude higher than for traditional GaAs/AlGaAs heterostructures. The mobility-sheet carrier concentration product for these two dimensional systems might also exceed that for GaAs/AlGaAs heterostructures and can be further enhanced by doping the conducting channels and by using “piezoelectric” doping. Current densities over 20 A mm−1 can be reached in GaN-based high electron mobility transistors (HEMTs). These high current values can be combined with very high breakdown voltages in high-power HEMTs, which are expected to reach several thousand volts. Recent Monte Carlo simulations point to strong ballistic and overshoot effects in GaN and related materials, which should be even more pronounced than in GaAs-based compounds but at much higher electric fields. This should allow us to achieve faster switching, minimizing the power dissipation during switching events. Self-heating, which is unavoidable in power devices, raises operating temperatures of power devices well above the ambient temperature. For GaN-based devices, the use of SiC substrates allows to combine the best features of both GaN and SiC technologies; and GaN/SiC-based semiconductors and heterostructures should find numerous applications in power electronics.