5,677 research outputs found

    Pterodactyl: Development and Comparison of Control Architectures for a Mechanically Deployed Entry Vehicle

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    The Pterodactyl project, seeks to advance the current state-of-the-art for entry vehicles by developing novel guidance and control technologies for Deployable Entry Vehicles (DEVs) that can be applied to various entry vehicle configurations. This paper details the efforts on the NASA-funded Pterodactyl project to investigate and implement multiple control techniques for an asymmetric mechanical DEV. We design multiple control architectures for a Pterodactyl Baseline Vehicle (PBV) and evaluate their performance in achieving varying guidance commands during entry. The control architectures studied are (i) propulsive control systems such as reaction control systems and (ii) non-propulsive control systems such as aerodynamic control surfaces and internal moving masses. For each system, state-feedback integral controllers based on linear quadratic regulator (LQR) optimal control methods are designed to track guidance commands of either (i) bank angle or (ii) angle of attack and sideslip angle as determined by the desired guidance trajectory. All control systems are compared for a lunar return reference mission and by providing a comparative analysis of these systems, configurations, and performance, the efforts detailed in this paper and the Pterodactyl project as a whole will help entry vehicle system designers determine suitable control architectures for integration with DEVs and other entry vehicle types

    Does "Could" Lead to Good? Toward a Theory of Moral Insight

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    We introduce the construct of moral insight and study how it can be elicited when people face ethical dilemmas—challenging decisions that feature tradeoffs between competing and seemingly incompatible values. Moral insight consists of discovering solutions that move beyond selecting one conflicting ethical option over another. Moral insight encompasses both a cognitive process and a discernible output: it involves the realization that an ethical dilemma might be addressed other than by conceding one set of moral imperatives to meet another, and it involves the generation of solutions that allow competing objectives to be met. Across four studies, we find that moral insight is generated when individuals are prompted to consider the question "What could I do?" in place of their intuitive approach of considering "What should I do?" Together, these studies point toward a theory of moral insight and important practical implications

    HLA-B*57:01 Allele Prevalence in HIV-infected North American Subjects and the Impact of Allele Testing on the Incidence of Abacavir-associated Hypersensitivity Reaction in HLA-B*57:01-negative Subjects

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    BACKGROUND: The presence of the HLA-B*57:01 allele in HIV-infected subjects is associated with a higher risk of abacavir-associated hypersensitivity reaction (ABC HSR). HLA-B*57:01 allele prevalence varies in different populations, but HLA-B*57:01 testing with immunological confirmation has had a negative predictive value for ABC HSR between 97 and 100%. METHODS: In the ASSURE study (EPZ113734), the HLA-B*57:01 prevalence in virologically suppressed, antiretroviral treatment-experienced, HIV-infected subjects from the United States, including Puerto Rico, was assessed. RESULTS: Three hundred eighty-five subjects were screened; 13 were HLA-B*57:01 positive and 372 were negative. Only HLA-B*57:01-negative, abacavir-naive subjects were eligible to enroll into the ASSURE trial. Eleven of the 13 subjects who possessed the HLA-B*57:01 allele were white, the other 2 were African-American. There was no geographic clustering of HLA-B*57:01-positive subjects, and the incidence correlated roughly with those states with the greatest numbers of subjects screened. Similarly, there was no statistically significant correlation between subjects who possessed or lacked the allele and age, gender, ethnicity or CD4+ T-cell numbers. The incidence of ABC HSR following abacavir initiation was also evaluated. Only 1 of 199 HLA-B*57:01-negative subjects (an African-American male) randomized to receive abacavir-containing treatment developed symptoms consistent with suspected ABC HSR; ABC HSR was not immunologically confirmed. CONCLUSIONS: These findings confirm the utility of HLA-B*57:01 allele testing to reduce the frequency of ABC HSR. The prevalence of HLA-B*57:01 positivity was higher in white than in African-American subjects. In HLA-B*57:01-negative subjects, suspected ABC HSR is very rare, but should lead to discontinuation of abacavir when ABC HSR cannot be definitively excluded from the differential diagnosis. TRIAL REGISTRATION: The ASSURE (EPZ113734) study was registered on ClinicalTrials.gov registration on April 8th 2010 and the registration number is NCT01102972

    Detection of human immunodeficiency virus RNAs in living cells using Spinach RNA aptamers

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    Many techniques currently used to measure HIV RNA production in cells suffer from limitations that include high background signal or the potential to destroy cellular context. Fluorophore-binding RNA aptamers offer the potential for visualizing RNAs directly in living cells with minimal cellular perturbation. We inserted a sequence encoding a fluorophore-binding RNA aptamer, known as Spinach, into the HIV genome such that predicted RNA secondary structures in both Spinach and HIV were preserved. Chimeric HIV-Spinach RNAs were functionally validated in vitro by testing their ability to enhance the fluorescence of a conditional fluorophore (DFHBI), which specifically binds Spinach. Fluorescence microscopy and PCR were used to verify expression of HIV-Spinach RNAs in human cells. HIV-1 gag RNA production and fluorescence were measured by qPCR and fluorometry, respectively. HIV-Spinach RNAs were fluorometrically detectable in vitro and were transcribed in human cell lines and primary cells, with both spliced and unspliced species detected by PCR. HIV-Spinach RNAs were visible by fluorescence microscopy in living cells, although signal was reproducibly weak. Cells expressing HIV-Spinach RNAs were capable of producing fluorometrically detectable virions, although detection of single viral particles was not possible. In summary, we have investigated a novel method for detecting HIV RNAs in living cells using the Spinach RNA aptamer. Despite the limitations of the present aptamer/fluorophore combination, this is the first application of this technology to an infectious disease and provides a foundation for future research into improved methods for studying HIV expression

    Framing Expectations in Early HIV Cure Research

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    Language used to describe clinical research represents a powerful opportunity to educate volunteers. In the case of HIV cure research there is an emerging need to manage expectations by using the term ‘experiment’. Cure experiments are proof-of-concept studies designed to evaluate novel paradigms to reduce persistent HIV-1 reservoirs, without any expectation of medical benefit

    Expanding Ethical Standards of HMR: Necessary Evils and the Multiple Dimensions of Impact

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    Ethical challenges abound in HRM. Each day, in the course of executing and communicating HR decisions, managers have the potential to change, shape, redirect, and fundamentally alter the course of other people\u27s lives. Managers make hiring decisions that reward selected applicants with salaries, benefits, knowledge, and skills, but leave the remaining applicants bereft of these opportunities and advantages. Managers make promotion decisions that reward selected employees with raises, status, and responsibility, leaving other employees wondering about their future and their potential. Managers make firing and lay-off decisions in order to improve corporate performance, all the while harming the targeted individuals and even undermining the commitment and energy of survivors. Even when managers complete performance appraisals and deliver performance feedback, they may inspire one employee and devastate another. For each HR practice, there are winners and there are losers: Those who get the job, or receive a portfolio of benefits, and those who do not

    Afferent activity to necklace glomeruli is dependent on external stimuli

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    <p>Abstract</p> <p>Background</p> <p>The main olfactory epithelium (MOE) is a complex organ containing several functionally distinct subpopulations of sensory neurons. One such subpopulation is distinguished by its expression of the guanylyl cyclase GC-D. The axons of GC-D-expressing (GC-D+) neurons innervate 9–15 "necklace" glomeruli encircling the caudal main olfactory bulb (MOB). Chemosensory stimuli for GC-D+ neurons include two natriuretic peptides, uroguanylin and guanylin, and CO<sub>2</sub>. However, the biologically-relevant source of these chemostimuli is unclear: uroguanylin is both excreted in urine, a rich source of olfactory stimuli for rodents, and expressed in human nasal epithelium; CO<sub>2 </sub>is present in both inspired and expired air.</p> <p>Findings</p> <p>To determine whether the principal source of chemostimuli for GC-D+ neurons is external or internal to the nose, we assessed the consequences of removing external chemostimuli for afferent activity to the necklace glomeruli. To do so, we performed unilateral naris occlusions in <it>Gucy2d-Mapt-lacZ </it><sup>+/- </sup>mice [which express a β-galactosidase (β-gal) reporter specifically in GC-D+ neurons] followed by immunohistochemistry for β-gal and a glomerular marker of afferent activity, tyrosine hydroxylase (TH). We observed a dramatic decrease in TH immunostaining, consistent with reduced or absent afferent activity, in both necklace and non-necklace glomeruli ipsilateral to the occluded naris.</p> <p>Conclusion</p> <p>Like other MOB glomeruli, necklace glomeruli exhibit a large decrease in afferent activity upon removal of external stimuli. Thus, we conclude that activity in GC-D+ neurons, which specifically innervate necklace glomeruli, is not dependent on internal stimuli. Instead, GC-D+ neurons, like other OSNs in the MOE, primarily sense the external world.</p

    Final Cultural Resources Report For The Salt Creek Midstream, LLC Proposed Waha II Pipeline Project On State Of Texas Lands In Reeves County, Texas

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    Enercon Services, Inc. (ENERCON), in support of Salt Creek Midstream, LLC, conducted an intensive archeological survey for the proposed Waha II Pipeline Project. The proposed pipeline is approximately 27.33 miles in length, located near Pecos, Texas in Reeves County. This report encompasses only the two State of Texas Lands, administered by the Texas General Land Office (TGLO), segments of the proposed Waha II Pipeline Project which is approximately 0.69-miles (3,666 feet) in length in Reeves County. The State of Texas Lands portion of the project area is mapped on the United States Geological Survey (USGS) Toyah Lake, Tex. (1963), and Old X Ranch, Tex. (1963, Photorevised 1981), 7.5 Minute Quadrangles. The construction corridor consists of a 50-foot-wide permanent pipeline right-of-way (ROW) and a 50-footwide temporary workspace corridor. The cultural resources survey corridor was 100 feet wide for the entire 0.69-mile length of the pipeline segment through the State of Texas Lands. The total area inspected during the cultural resources survey of the State of Texas Lands was 8.43 acres (3.41 hectares). The survey of the State of Texas property was completed under Texas Antiquities Permit No. 9017. The cultural resources field investigation on State of Texas Lands occurred on August 2 and 3, 2018 by J. Matthew Oliver and Gary D. Edington and consisted of an intensive pedestrian survey utilizing transects not spaced greater than 15 meters apart with shovel tests. The field investigation was conducted in accordance with the Texas Historical Commission (THC) Archeological Survey Standards for Texas. The entire project was supervised by Gary D. Edington, an ENERCON archeologist who meets the U.S. Secretary of the Interior’s Professional Qualification Standards for archeology as set forth in 36 CFR 61. The cultural resources survey resulted in the observation of two isolated finds (IF). IF#8 is a single lithic flake of brown chert observed on the surface in the east tract of State of Texas Lands. IF#9 is a small bulldozer push-pile of old wooden fence posts and barbed wire observed adjacent to the east fence line of the east tract of Texas State lands. IF#8 and IF#9 lack information potential and are not eligible for the National Register of Historic Places (NRHP) or State Antiquities Landmarks (SAL). The cultural resources survey did not result in finding any additional historic or prehistoric artifacts, features, cultural lenses, or sites over 50 years of age on State of Texas Lands. No archeological sites were encountered, and no artifacts were collected. Therefore, it is recommended that the project will have no effect on any cultural resources that may qualify for inclusion to the NRHP on State of Texas Lands. No further cultural resources investigations are recommended prior to construction of the proposed Waha II Pipeline project on State of Texas Lands. If cultural material, including sites, features, or artifacts that are 50 years old or older are encountered within the ROW during construction of this project, work in the area must cease and the regional THC Archeologist must be immediately be notified
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