Design and construction of a dynamometer

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011."June 2011." Cataloged from PDF version of thesis.Includes bibliographical references (p. 20).Access to a dynamometer is a useful tool for any electrical system where the motors must be selected from various suppliers and fully characterized. Motor suppliers usually provide a torque, speed, efficiency curve, but it frequently lacks complete motor characterization and includes motor controller losses in the total system loss. The dynamometer presented in this thesis is primarily designed for testing of high efficiency motors and motor controllers in the power and speed range requires for competition in the World Solar Challenge, a transcontinental race for solar electric vehicles. The testing specifications of a solar electric vehicles are uncommon among motor testing needs because it requires high torque, low power, high efficiency, and the only a small operating range. This thesis covers the design and construction of the dynamometer.by Rachel E. Batzer.S.B

Rates and patterns of great ape retrotransposition

Cataloged from PDF version of article.We analyzed 83 fully sequenced great ape genomes for mobile element insertions, predicting a total of 49,452 fixed and polymorphic Alu and long interspersed element 1 (L1) insertions not present in the human reference assembly and assigning each retrotransposition event to a different time point during great ape evolution. We used these homoplasy-free markers to construct a mobile element insertions-based phylogeny of humans and great apes and demonstrate their differential power to discern ape subspecies and populations. Within this context, we find a good correlation between L1 diversity and single-nucleotide polymorphism heterozygosity (r(2) = 0.65) in contrast to Alu repeats, which show little correlation (r(2) = 0.07). We estimate that the "rate" of Alu retrotransposition has differed by a factor of 15-fold in these lineages. Humans, chimpanzees, and bonobos show the highest rates of Alu accumulation-the latter two since divergence 1.5 Mya. The L1 insertion rate, in contrast, has remained relatively constant, with rates differing by less than a factor of three. We conclude that Alu retrotransposition has been the most variable form of genetic variation during recent human-great ape evolution, with increases and decreases occurring over very short periods of evolutionary time

Recently integrated Alu elements and human genomic diversity

A comprehensive analysis of two Alu Y lineage subfamilies was undertaken to assess Alu-associated genomic diversity and identify new Alu insertion polymorphisms for the study of human population genetics. Recently integrated Alu elements (283) from the Yg6 and Yi6 subfamilies were analyzed by polymerase chain reaction (PCR), and 25 of the loci analyzed were polymorphic for insertion presence/absence within the genomes of a diverse array of human populations. These newly identified Alu insertion polymorphisms will be useful tools for the study of human genomic diversity. Our screening of the Alu insertion loci also resulted in the recovery of several young Alu elements that resided at orthologous positions in nonhuman primate genomes. Sequence analysis demonstrated these young Alu insertions were the products of gene conversion events of older, preexisting Alu elements or independent parallel forward insertions of older Alu elements in the same short genomic region. The level of gene conversion between Alu elements suggests that it may have an influence on the single nucleotide polymorphism within Alu elements in the genome. We have also identified two genomic deletions associated with the retroposition and insertion of Alu Y lineage elements into the human genome. This type of Alu retroposition-mediated genomic deletion is a novel source of lineage-specific evolution within primate genomes

Sequencing, identification and mapping of primed L1 elements (SIMPLE) reveals significant variation in full length L1 elements between individuals

Background: There are over a half a million copies of L1 retroelements in the human genome which are responsible for as much as 0.5% of new human genetic diseases. Most new L1 inserts arise from young source elements that are polymorphic in the human genome. Highly active polymorphic “hot” L1 source elements have been shown to be capable of extremely high levels of mobilization and result in numerous instances of disease. Additionally, hot polymorphic L1s have been described to be highly active within numerous cancer genomes. These hot L1s result in mutagenesis by insertion of new L1 copies elsewhere in the genome, but also have been shown to generate additional full length L1 insertions which are also hot and able to further retrotranspose. Through this mechanism, hot L1s may amplify within a tumor and result in a continued cycle of mutagenesis. Results and conclusions We have developed a method to detect full-length, polymorphic L1 elements using a targeted next generation sequencing approach, Sequencing Identification and Mapping of Primed L1 Elements (SIMPLE). SIMPLE has 94% sensitivity and detects nearly all full-length L1 elements in a genome. SIMPLE will allow researchers to identify hot mutagenic full-length L1s as potential drivers of genome instability. Using SIMPLE we find that the typical individual has approximately 100 non-reference, polymorphic L1 elements in their genome. These elements are at relatively low population frequencies relative to previously identified polymorphic L1 elements and demonstrate the tremendous diversity in potentially active L1 elements in the human population. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1374-y) contains supplementary material, which is available to authorized users

Alu fossil relics - distribution and insertion polymorphism

Screening of a human genomic library with an oligonucleotide probe specific for one of the young subfamilies of Alu repeats (Ya5/8) resulted in the identification of several hundred positive clones. Thirty-three of these clones were analyzed in detail by DNA sequencing. Oligonucleotide primers complementary to the unique sequence regions flanking each Alu repeat were used in PCR-based assays to perform phylogenetic analyses, chromosomal localization, and insertion polymorphism analyses within different human population groups. All 33 Alu repeats were present only in humans and absent from orthologous positions in several nonhuman primate genomes. Seven Alu repeats were polymorphic for their presence/absence in three different human population groups, making them novel identical-by-descent markers for the analysis of human genetic diversity and evolution. Nucleotide sequence analysis of the polymorphic Alu repeats showed an extremely low nucleotide diversity compared with the subfamily consensus sequence with an average age of 1.63 million years old. The young Alu insertions do not appear to accumulate preferentially on any individual human chromosome

Multiplex polymerase chain reaction for simultaneous quantitation of human nuclear, mitochondrial, and male Y-chromosome DNA: Application in human identification

Human forensic casework requires sensitive quantitation of human nuclear (nDNA), mitochondrial (mtDNA), and male Y-chromosome DNA from complex biomaterials. Although many such systems are commercially available, no system is capable of simultaneously quantifying all three targets in a single reaction. Most available methods either are not multiplex compatible or lack human specificity. Here, we report the development of a comprehensive set of human-specific, target-specific multiplex polymerase chain reaction (PCR) assays for DNA quantitation. Using TaqMan-MGB probes, our duplex qPCR for nDNA/mtDNA had a linear quantitation range of 100 ng to 1 pg, and our triplex qPCR assay for nDNA/mtDNA/male Y DNA had a linear range of 100-0.1 ng. Human specificity was demonstrated by the accurate detection of 0.05 and 5% human DNA from a complex source of starting templates. Target specificity was confirmed by the lack of cross-amplification among targets. A high-throughput alternative for human gender determination was also developed by multiplexing the male Y primer/probe set with an X-chromosome-based system. Background cross-amplification with DNA templates derived from 14 other species was negligible aside from the male Y assay which produced spurious amplifications from other nonhuman primate templates. Mainstream application of these assays will undoubtedly benefit forensic genomics. © 2004 Elsevier Inc. All rights reserved