Bodies, Ideas, and Dynamics: Historical Perspectives on Systems Thinking in Engineering

Today, the idea that technology consists not simply of individual machines but of systems of components and interconnections underlies much of engineering theory and practice. Yet this idea is relatively new in the history of technology; it evolved over a long period, spanning more than a century, as engineers grappled with the implications of machinery and collections of apparatus that spread over broad geographical areas. A historical perspective on systems thinking provides a critical background for contemplating new directions in “engineering systems,” by highlighting the problems that have constantly challenged engineers, as well as the new puzzles posed by today’s world

"Datum for its own annihilation" : feedback, control, and computing, 1916-1945

Thesis (Ph. D.)--Massachusetts Institute of Technology, Program in Science, Technology, and Society, 1996.Includes bibliographical references.by David A. Mindell.Ph.D

The Leech and the Physician: Biology, Etymology, and Medical Practice with Hirudinea medicinalis

The history of the word “leech” and the practice of leeching reveal interconnected social histories. We give the linguistic and medical histories of the word, and explore its biology and clinical history. Our historical account extends from the earliest known record of leeching to current research. Despite historical variation in its reputation as a therapeutic technique, leeching remains useful today in a number of applications. Further investigation may well disclose even more uses for the leech, particularly for its enzymes with anesthetic, anticoagulant, and antimetastatic properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42411/1/268-24-7-878_00240878.pd

Systematics within Gyps vultures: a clade at risk

BACKGROUND: Populations of the Oriental White-backed Vulture (Gyps bengalensis) have declined by over 95% within the past decade. This decline is largely due to incidental consumption of the non-steroidal anti-inflammatory veterinary pharmaceutical diclofenac, commonly used to treat domestic livestock. The conservation status of other Gyps vultures in southern Asia is also of immediate concern, given the lack of knowledge regarding status of their populations and the continuing existence of taxonomic uncertainties. In this study, we assess phylogenetic relationships for all recognized species and the majority of subspecies within the genus Gyps. The continuing veterinary use of diclofenac is an unknown but potential risk to related species with similar feeding habits to Gyps bengalensis. Therefore, an accurate assessment of the phylogenetic relationships among Gyps vultures should aid in their conservation by clarifying taxonomic uncertainties, and enabling inference of their respective relatedness to susceptible G. bengalensis. RESULTS: Phylogenetic results using mitochondrial cytB, ND2 and control region sequence data indicate a recent and rapid diversification within the genus Gyps. All recognized species formed monophyletic groups with high statistical support, with the exception of the Eurasian Vulture, for which specimens identified as subspecies G. fulvus fulvescens appear closely related to the Himalayan Vulture (G. himalayensis). In all analyses, the earliest divergence separated the Oriental White-backed Vulture from other Gyps taxa, with the next diverging taxon being either the African White-backed Vulture (G. africanus), or the Himalayan Vulture. All analyses supported a sister relationship between the Eurasian Vulture (G. f. fulvus), and Rüppell's Vulture (G. rueppellii), with this clade being sister to another consisting of the two taxa of "Long-billed" Vulture (G. indicus indicus and G. i. tenuirostris), and the Cape Vulture (G. coprotheres). These molecular phylogenies strongly support the treatment of indicus and tenuirostris as separate species, as does morphological data showing that these two taxa of similar overall size differ in proportions, especially in rostral, alar, and pedal characters. In addition, grouping of bengalensis and africanus together in the genus Pseudogyps, as historically proposed, is not upheld based on mitochondrial data. CONCLUSION: Both molecular and morphological data provide strong support for considering the "Long-billed" Vulture to be comprised of two species (G. indicus and G. tenuirostris), and further analysis is warranted to determine the taxonomic distinctiveness of G. f. fulvescens. Our phylogenetic analyses and conservative estimates suggest the diversification of Gyps taxa to be within the past 6 million years. Diclofenac susceptibility has been previously demonstrated for four Gyps species (G. indicus, G. fulvus, G. africanus, G. bengalensis), and the phylogenetic position of these species each forming a sister relationship with at least one of the remaining species, support concern that other Gyps taxa may be susceptible as well. Determining genetic and evolutionary distinctiveness for Gyps lineages is increasingly important as a breeding program is being established to prevent extinction

It\u27s not too Late for the Harpy Eagle (Harpia harpyja): High Levels Of Genetic Diversity and Differentiation Can Fuel Conservation Programs

Background: The harpy eagle (Harpia harpyja) is the largest Neotropical bird of prey and is threatened by human persecution and habitat loss and fragmentation. Current conservation strategies include local education, captive rearing and reintroduction, and protection or creation of trans-national habitat blocks and corridors. Baseline genetic data prior to reintroduction of captive-bred stock is essential for guiding such efforts but has not been gathered previously. Methodology/Findings: We assessed levels of genetic diversity, population structure and demographic history for harpy eagles using samples collected throughout a large portion of their geographic distribution in Central America (n = 32) and South America (n = 31). Based on 417 bp of mitochondrial control region sequence data, relatively high levels of haplotype and nucleotide diversity were estimated for both Central and South America, although haplotype diversity was significantly higher for South America. Historical restriction of gene flow across the Andes (i.e. between our Central and South American subgroups) is supported by coalescent analyses, the haplotype network and significant FST values, however reciprocally monophyletic lineages do not correspond to geographical locations in maximum likelihood analyses. A sudden population expansion for South America is indicated by a mismatch distribution analysis, and further supported by significant (p,0.05) negative values of Fu and Li’s DF and F, and Fu’s FS. This expansion, estimated at approximately 60 000 years BP (99 000–36 000 years BP 95% CI), encompasses a transition from a warm and dry time period prior to 50 000 years BP to an interval of maximum precipitation (50 000–36 000 years BP). Notably, this time period precedes the climatic and habitat changes associated with the last glacial maximum. In contrast, a multimodal distribution of haplotypes was observed for Central America suggesting either population equilibrium or a recent decline. Significance: High levels of mitochondrial genetic diversity in combination with genetic differentiation among subgroups within regions and between regions highlight the importance of local population conservation in order to preserve maximal levels of genetic diversity in this species. Evidence of historically restricted female-mediated gene flow is an important consideration for captive-breeding programs

Evolutionary biology for the 21st century

New theoretical and conceptual frameworks are required for evolutionary biology to capitalize on the wealth of data now becoming available from the study of genomes, phenotypes, and organisms - including humans - in their natural environments.Molecular and Cellular BiologyOrganismic and Evolutionary Biolog

Solvent accessibility changes in a Na+-dependent C4-dicarboxylate transporter suggest differential substrate effects in a multistep mechanism

The divalent anion sodium symporter (DASS) family (SLC13) play critical roles in metabolic homeostasis, influencing many processes including fatty acid synthesis, insulin resistance, and adiposity. DASS transporters catalyse the Na+-driven concentrative uptake of Krebs cycle intermediates and sulfate into cells; disrupting their function can protect against age-related metabolic diseases and can extend lifespan. An inward-facing crystal structure and an outward-facing model of a bacterial DASS family member, VcINDY from Vibrio cholerae, predict an elevator-like transport mechanism involving a large rigid body movement of the substrate binding site. How substrate binding influences the conformational state of VcINDY is currently unknown. Here, we probe the interaction between substrate binding and protein conformation by monitoring substrate-induced solvent accessibility changes of broadly distributed positions in VcINDY using a site-specific alkylation strategy. Our findings reveal that accessibility to all positions tested are modulated by the presence of substrates, with the majority becoming less accessible in the presence of saturating concentrations of both Na+ and succinate. We also observe separable effects of Na+ and succinate binding at several positions suggesting distinct effects of the two substrates. Furthermore, accessibility changes to a solely succinate-sensitive position suggests that substrate binding is a low affinity, ordered process. Mapping these accessibility changes onto the structures of VcINDY suggests that Na+ binding drives the transporter into an as-yet-unidentified conformational state, involving rearrangement of the substrate binding site-associated re-entrant hairpin loops. These findings provide insight into the mechanism of VcINDY, which is currently the only structural-characterised representative of the entire DASS family

The Use of Genetics for the Management of a Recovering Population: Temporal Assessment of Migratory Peregrine Falcons in North America

Background: Our ability to monitor populations or species that were once threatened or endangered and in the process of recovery is enhanced by using genetic methods to assess overall population stability and size over time. This can be accomplished most directly by obtaining genetic measures from temporally-spaced samples that reflect the overall stability of the population as given by changes in genetic diversity levels (allelic richness and heterozygosity), degree of population differentiation (FST and DEST), and effective population size (Ne). The primary goal of any recovery effort is to produce a longterm self-sustaining population, and these genetic measures provide a metric by which we can gauge our progress and help make important management decisions. Methodology/Principal Findings: The peregrine falcon in North America (Falco peregrinus tundrius and anatum) was delisted in 1994 and 1999, respectively, and its abundance will be monitored by the species Recovery Team every three years until 2015. Although the United States Fish and Wildlife Service makes a distinction between tundrius and anatum subspecies, our genetic results based on eleven microsatellite loci suggest limited differentiation that can be attributed to an isolation by distance relationship and warrant no delineation of these two subspecies in its northern latitudinal distribution from Alaska through Canada into Greenland. Using temporal samples collected at Padre Island, Texas during migration (seven temporal time periods between 1985–2007), no significant differences in genetic diversity or significant population differentiation in allele frequencies between time periods were observed and were indistinguishable from those obtained from tundrius/anatum breeding locations throughout their northern distribution. Estimates of harmonic mean Ne were variable and imprecise, but always greater than 500 when employing multiple temporal genetic methods. Conclusions/Significance: These results, including those from simulations to assess the power of each method to estimate Ne, suggest a stable or growing population, which is consistent with ongoing field-based monitoring surveys. Therefore, historic and continuing efforts to prevent the extinction of the peregrine falcon in North America appear successful with no indication of recent decline, at least from the northern latitude range-wide perspective. The results also further highlight the importance of archiving samples and their use for continual assessment of population recovery and long-term viability

Distribution of DHPS Mutations Among ITS Subtypes of P. carinii f. sp. hominis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92387/1/j.1550-7408.2001.tb00481.x.pd