819 research outputs found

    Servomotor-Linked Articulated Versatile End Effector (SLAVE2)

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    A strategy is presented for the design and construction of a large master/slave-controlled, five-finger robotic hand. Each of the five fingers will possess four independent axes each driven by a brushless DC servomotor and, thus, four degrees-of-freedom. It is proposed that commercially available components be utilized as much as possible to fabricate a working laboratory model of the device with an anticipated overall length of approximately three feet (0.9 m). The fingers are to be designed to accommodate proximity, tactile, or force/torque sensors imbedded in their structure. In order to provide for the simultaneous control of the operator wears a specially instrumented glove which produces control signals corresponding to the finger configuration and which is capable of conveying sensor feedback signals to the operator. Two dexterous hand master devices are currently commercially available for this application with both undergoing continuing development

    Superior Real Estate Investment Performance: Enigma or Illusion? A Critical Review of the Literature

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    [Excerpt] The purpose of this paper is to critique the existing empirical evidence on the investment performance of real estate relative to alternative asset categories. The key issue which guides this review of the investment performance literature is whether abnormal real estate returns are merely an illusion which arises from the shortcomings associated with various real estate performance studies or are the result of an omission of more fundamental factors. We suggest that any superior return is a short-run phenomenon, because, according to capital market theory, all assets should exhibit similar risk and return characteristics in the long run. If real estate continues to possess superior performance in the long run, then this implies that fundamental factors have been omitted from the real estate pricing model. Moreover, we will propose that a world in which the capital asset pricing model holds might be compatible with the existing evidence, because most of the prior studies have focused on total risk rather than on systematic risk. l Consequently, all assets can plot on the security market line in equilibrium, given a CAPM world, regardless of whether one asset (portfolio) such as real estate dominates another asset (portfolio) such as stocks from a mean-variance perspective

    A qualitative assessment of direct-labeled cDNA products prior to microarray analysis

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    BACKGROUND: The success of the microarray process in determining differential gene expression of thousands of genes is dependent upon the quality and integrity of the starting RNA, this being particularly true of direct labeling via a reverse transcription procedure. Furthermore, an RNA of reasonable quality still may not yield reliable hybridization data if the labeling efficiency was poor. RESULTS: Here we present a novel assay for assessing the quality of directly labeled fluorescent cDNA prior to microarray hybridization utilizing the Agilent 2100 Bioanalyzer, which employs microfluidic technology for the analysis of nucleic acids and proteins. Using varying amounts of RNase to simulate RNA degradation, we show the strength of this un-advertised assay in determining the relative amounts of cDNA obtained from a direct labeling reaction. CONCLUSION: Utilization of this method in the lab will help to prevent the costly mistake of hybridizing poor quality direct labeled products to expensive arrays

    RNA polymerase is poised for activation across the genome

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    Regulation of gene expression is integral to the development and survival of all organisms. Transcription begins with the assembly of a pre-initiation complex at the gene promoter, followed by initiation of RNA synthesis and the transition to productive elongation. In many cases, recruitment of RNA polymerase II (Pol II) to a promoter is necessary and sufficient for activation of genes. However, there are a few notable exceptions to this paradigm, including heat shock genes and several proto-oncogenes, whose expression is attenuated by regulated stalling of polymerase elongation within the promoter-proximal region. To determine the importance of polymerase stalling for transcription regulation, we carried out a genome-wide search for Drosophila melanogaster genes with Pol II stalled within the promoter-proximal region. Our data show that stalling is widespread, occurring at hundreds of genes that respond to stimuli and developmental signals. This finding indicates a role for regulation of polymerase elongation in the transcriptional responses to dynamic environmental and developmental cues

    Ultra-high spatial resolution BOLD fMRI in humans using combined segmented-accelerated VFA-FLEET with a recursive RF pulse design

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    Purpose To alleviate the spatial encoding limitations of single-shot EPI by developing multi-shot segmented EPI for ultra-high-resolution fMRI with reduced ghosting artifacts from subject motion and respiration. Methods Segmented EPI can reduce readout duration and reduce acceleration factors, however, the time elapsed between segment acquisitions (on the order of seconds) can result in intermittent ghosting, limiting its use for fMRI. Here, "FLEET" segment ordering--where segments are looped over before slices--was combined with a variable flip angle progression (VFA-FLEET) to improve inter-segment fidelity and maximize signal for fMRI. Scaling a sinc pulse's flip angle for each segment (VFA-FLEET-Sinc) produced inconsistent slice profiles and ghosting, therefore, a recursive Shinnar-Le Roux (SLR) RF pulse design was developed (VFA-FLEET-SLR) to generate unique pulses for every segment that together produce consistent slice profiles and signals. Results The temporal stability of VFA-FLEET-SLR was compared against conventional-segmented EPI and VFA-FLEET-Sinc at 3 T and 7 T. VFA-FLEET-SLR showed reductions in both intermittent and stable ghosting compared to conventional-segmented and VFA-FLEET-Sinc, resulting in improved image quality with a minor trade-off in temporal SNR. Combining VFA-FLEET-SLR with acceleration, we achieved a 0.6-mm isotropic acquisition at 7 T--without zoomed imaging or partial Fourier--demonstrating reliable detection of BOLD responses to a visual stimulus. To counteract the increased repetition time from segmentation, simultaneous multi-slice VFA-FLEET-SLR was demonstrated using RF-encoded controlled aliasing. Conclusions VFA-FLEET with a recursive RF pulse design supports acquisitions with low levels of artifact and spatial blur, enabling fMRI at previously inaccessible spatial resolutions with a "full-brain" field of view.Comment: 51 pages (including supplement), 8 main figures, 6 supporting figures. For supporting videos (8), please visit https://github.com/aveberman/vfa-fleet. Note: this work has been accepted for publication at Magnetic Resonance in Medicin

    Association of left ventricular longitudinal strain with central venous oxygen saturation and serum lactate in patients with early severe sepsis and septic shock

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    Syftet med denna studie Àr att synliggöra pedagogers syn pÄ förÀldrasamverkan i förskolan. Vi har Àven intresserat oss pÄ samverkan mellan pedagogerna och förÀldrar med annat modersmÄl Àn svenska. VÄr studie grundar sig pÄ observationer kring bemötande av förÀldrar pÄ förskolan. Vi undersökte hur pedagogerna sÄg pÄ förÀldrasamverkan och hur de arbetar kring samverkan med förÀldrar, för att kunna fÄ en bredare syn i vÄr studie om hur samverkan fungerar pÄ de aktuella förskolorna. Som metod anvÀnde vi kvalitativ intervju dÄ detta lÀmpade sig vÀl för oss för att vi skulle kunna fÄ en bredare syn om hur samverkan fungerar pÄ de aktuella förskolorna. Intervjuer ger mer exakta svar och det underlÀttar för oss som intervjuar att stÀlla följdfrÄgor. Resultatet visar att samverkan med förÀldrar har ökat i förskolan och blivit en stor del av verksamheten. Pedagogerna försöker engagera sig mycket i arbetet med förÀldrasamverkan och letar efter möjligheter för att skapa en bra kommunikation med förÀldrar som har annat modersmÄl Àn svenska. Resultaten visar Àven att pedagogerna menar att oavsett om förÀldrarna behÀrskar det svenska sprÄket eller inte sÄ anstrÀnger de sig för att visa förÀldrarna att de Àr viktiga i verksamheten

    Investigating the role of time in affective forecasting: temporal influences on forecasting accuracy.

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    Using extensive diary data from people taking their driver's license exam, the authors investigated the role of time in affective forecasting accuracy. Replicating existing findings, participants grossly overestimated the intensity and duration of their negative affect after failure and only slightly overestimated the intensity and duration of their positive affect after success. Extending existing findings, participants accurately predicted a decrease of their affective reactions over time but underestimated the speed with which this decrease would occur. In addition, they showed greater forecasting accuracy for positive affect than negative affect when the exam was distant and greater forecasting accuracy for negative affect than positive affect when the exam was close. The motivational processes underlying these findings are being discussed. © 2007 by the Society for Personality and Social Psychology, Inc

    Finding character strengths through loss: an extension of Peterson and Seligman (2003)

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    People can experience positive changes even in the midst of adversity and loss. We investigated character strengths following three recent shooting tragedies. Using an Internet database of respondents to the Values in Action Inventory of Strengths (VIA-IS), we compared responses from three groups of participants (N = 31,429) within close proximity of each event: those who completed it eight months prior to the event, and one month and two months after. Results suggested that for one of the events, participants who completed the VIA-IS after the event showed slightly different levels of self-reported character strengths compared to participants who completed the VIA-IS before the event, with some mean levels higher and others lower. The observed differences in character strengths were inconsistent across follow-up periods, and effect sizes were small (d values from –0.13 to 0.15). These findings raise questions about whether and how tragedies might catalyze differences in character strengths

    Responsiveness of Diverse Families of Loblolly Pine to Fertilization: Eight-Year Results from SETRES-2

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    Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003
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