3,569 research outputs found

    LOCK CONGESTION AND ITS IMPACT ON GRAIN BARGE RATES ON THE UPPER MISSISSIPPI RIVER

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    An anticipated increase in lock delays on the upper Mississippi River has generated concern about its future navigational efficiency. The objective of this paper is to identify selected factors affecting lock delay on the River's busiest locks and to examine the impact of lock delay on grain barge rates. Results show that lock unavailability, traffic level, and delay at nearby locks affect lock delay. Further, barge rates are affected by lock delay, however, the impact is modest.Public Economics,

    Cointegration and Causality Analysis of World Vegetable Oil and Crude Oil Prices

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    Because of the recent soaring petroleum price and growing environmental concerns, biodiesel has become an important alternative fuel. Biodiesel is the mono alky esters made from a vegetable oil, such as soybean or rapeseed oil, or sometimes from animal fats. The escalation in world petroleum price has stimulated the demand for biodiesel, which consequently expanded the use of vegetable oils. This paper investigates the long-run interdependence between major edible oil prices and examines the dynamic relationship between vegetable and crude oil prices. The data consists of 378 weekly observations extending from the first week of January in 1999 to the fourth week of March in 2006. We apply time-series analytical mechanisms and directed acyclic graphs to four major traded edible oils prices, including soybean, sunflower, rapeseed and palm oils, along with one weighted average world crude oil price. Tentative results suggest one long-run cointegration relationship among those five oil prices. Also, the edible oil markets are well linked in contemporaneous time with the palm oil market initiating the new information; however, soybean oil price dominates the edible oil markets in the long run. The influence of crude oil price on edible oil prices is not significant over the study period.Resource /Energy Economics and Policy,

    ON or OFF?: Modulating the N-Methyl-D-Aspartate Receptor in Major Depression

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    Since the discovery that a single dose of ketamine, an N-methyl-D-aspartate receptor (NMDAR) antagonist, had rapid and long-lasting antidepressant effects, there has been increased interest in using NMDAR modulators in the pharmacotherapy of depression. Ketamine's efficacy seems to imply that depression is a disorder of NMDAR hyperfunctionality. However, studies showing that not all NMDAR antagonists are able to act as antidepressants challenge this notion. Furthermore, NMDAR co-agonists have also been gaining attention as possible treatments. Co-agonists such as D-serine and sarcosine have shown efficacy in both pre-clinical models and human trials. This raises the question of how both NMDAR antagonists and agonists are able to have converging behavioral effects. Here we critically review the evidence and proposed therapeutic mechanisms for both NMDAR antagonists and agonists, and collate several theories on how both activation and inhibition of NMDARs appear to have antidepressant effects

    Buoyant surface jets discharged into a strong crossflow

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    Analytical and experimental investigations were carried out for three-dimensional buoyant surface jets with strong ambient flow but without boundary attachment. A numerical model in curvilinear coordinates was developed from an integral jet analysis modified for buoyancy effects and included asymmetry of the jet. Detailed temperature distributions were measured in the laboratory with densimetric Froude numbers (FĚĄ) of 5, 10 and 15 and 0 velocity ratios (R) from 2 to 13. Experimental results showed that ambient crossflows can cause significant distortion of the jet, even for R = 13. Near the exit, the lower portion of the jet is swept toward the lee side of the jet. The resulting L-shaped cross section and the associated density instability may enhance spreading on the lee side and may contribute to the subsequent formation of bimodal temperature distributions. The jet bending increases as R decreases and as FĚĄ increases. Dilution increases with increasing FĚĄ and decreasing R. The model was calibrated against the entire set of measured temperatures for each run and is capable of predicting temperature 0 distributions to an accuracy of 0.63CËš. The agreement could probably be improved by using similarity profiles better suited to the actual jet cross sectional shape which was not known at the beginning of the research.U.S. Department of the InteriorU.S. Geological SurveyOpe

    Government Data and the Invisible Hand

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    If President Barack Obama\u27s new administration really wants to embrace the potential of Internet-enabled government transparency, it should follow a counter-intuitive but ultimately compelling strategy: reduce the federal role in presenting important government information to citizens. Today, government bodies consider their own Web sites to be a higher priority than technical infrastructures that open up their data for others to use. We argue that this understanding is a mistake. It would be preferable for government to understand providing reusable data, rather than providing Web sites, as the core of its online publishing responsibility. During the presidential campaign, all three major candidates indicated that they thought the federal government could make better use of the Internet. Barack Obama\u27s platform went the furthest and explicitly endorsed maling government data available online in universally accessible formats. Hillary Clinton, meanwhile, remarked that she wanted to see much more government information online. John McCain\u27s platform called for a new Office of Electronic Government. But the situation to which these candidates were responding-the wide gap between the exciting uses of Internet technology by private parties, on the one hand, and the government\u27s lagging technical infrastructure, on the other-is not new. A minefield of federal rules and a range of other factors, prevent government Web masters from keeping pace with the evergrowing potential of the Internet

    Study of stratified overflows and underflows

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    The study presents a general analysis of two-layered stratified flows taking into account effects of sidewall friction and variation of density with horizontal distance. The analysis is applied to the study of arrested thermal wedges and arrested cold water intrusions. Laboratory data were collected and analyzed and it was determined that bed roughness has a significant effect on the interfacial friction factor for arrested thermal wedges but not for arrested cold water intrusions. Friction factors were found to vary significantly along the wedges indicating that use of average values is perhaps undesirable. Local values of friction factor were found to increase with values of a local interfacial Reynolds number.U.S. Department of the InteriorU.S. Geological SurveyOpe

    Identification of N -Linked Glycosylation Sites in Human Testis Angiotensin-converting Enzyme and Expression of an Active Deglycosylated Form

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    The sites of glycosylation of Chinese hamster ovary cell expressed testicular angiotensin-converting enzyme (tACE) have been determined by matrix-assisted laser desorption ionization/time of flight/mass spectrometry of peptides generated by proteolytic and cyanogen bromide digestion. Two of the seven potential N-linked glycosylation sites, Asn90 and Asn109, were found to be fully glycosylated by analysis of peptides before and after treatment with a series of glycosidases and with endoproteinase Asp-N. The mass spectra of the glycopeptides exhibit characteristic clusters of peaks which indicate the N-linked glycans in tACE to be mostly of the biantennary, fucosylated complex type. This structural information was used to demonstrate that three other sites, Asn155, Asn337, and Asn586, are partially glycosylated, whereas Asn72 appears to be fully glycosylated. The only potential site that was not modified is Asn620. Sequence analysis of tryptic peptides obtained from somatic ACE (human kidney) identified six glycosylated and one unglycosylated Asn. Only one of these glycosylation sites had a counterpart in tACE. Comparison of the two proteins reveals a pattern in which amino-terminal N-linked sites are preferred. The functional significance of glycosylation was examined with a tACE mutant lacking the O-glycan-rich first amino-terminal 36 residues and truncated at Ser625. When expressed in the presence of the alpha-glucosidase I inhibitor N-butyldeoxynojirimycin and treated with endoglycosidase H to remove all but the terminal N-acetylglucosamine residues, it retained full enzymatic activity, was electrophoretically homogeneous, and is a good candidate for crystallographic studies

    Accountable Algorithms

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    Many important decisions historically made by people are now made by computers. Algorithms count votes, approve loan and credit card applications, target citizens or neighborhoods for police scrutiny, select taxpayers for IRS audit, grant or deny immigration visas, and more. The accountability mechanisms and legal standards that govern such decision processes have not kept pace with technology. The tools currently available to policymakers, legislators, and courts were developed to oversee human decisionmakers and often fail when applied to computers instead. For example, how do you judge the intent of a piece of software? Because automated decision systems can return potentially incorrect, unjustified, or unfair results, additional approaches are needed to make such systems accountable and governable. This Article reveals a new technological toolkit to verify that automated decisions comply with key standards of legal fairness. We challenge the dominant position in the legal literature that transparency will solve these problems. Disclosure of source code is often neither necessary (because of alternative techniques from computer science) nor sufficient (because of the issues analyzing code) to demonstrate the fairness of a process. Furthermore, transparency may be undesirable, such as when it discloses private information or permits tax cheats or terrorists to game the systems determining audits or security screening. The central issue is how to assure the interests of citizens, and society as a whole, in making these processes more accountable. This Article argues that technology is creating new opportunities—subtler and more flexible than total transparency—to design decisionmaking algorithms so that they better align with legal and policy objectives. Doing so will improve not only the current governance of automated decisions, but also—in certain cases—the governance of decisionmaking in general. The implicit (or explicit) biases of human decisionmakers can be difficult to find and root out, but we can peer into the “brain” of an algorithm: computational processes and purpose specifications can be declared prior to use and verified afterward. The technological tools introduced in this Article apply widely. They can be used in designing decisionmaking processes from both the private and public sectors, and they can be tailored to verify different characteristics as desired by decisionmakers, regulators, or the public. By forcing a more careful consideration of the effects of decision rules, they also engender policy discussions and closer looks at legal standards. As such, these tools have far-reaching implications throughout law and society. Part I of this Article provides an accessible and concise introduction to foundational computer science techniques that can be used to verify and demonstrate compliance with key standards of legal fairness for automated decisions without revealing key attributes of the decisions or the processes by which the decisions were reached. Part II then describes how these techniques can assure that decisions are made with the key governance attribute of procedural regularity, meaning that decisions are made under an announced set of rules consistently applied in each case. We demonstrate how this approach could be used to redesign and resolve issues with the State Department’s diversity visa lottery. In Part III, we go further and explore how other computational techniques can assure that automated decisions preserve fidelity to substantive legal and policy choices. We show how these tools may be used to assure that certain kinds of unjust discrimination are avoided and that automated decision processes behave in ways that comport with the social or legal standards that govern the decision. We also show how automated decisionmaking may even complicate existing doctrines of disparate treatment and disparate impact, and we discuss some recent computer science work on detecting and removing discrimination in algorithms, especially in the context of big data and machine learning. And lastly, in Part IV, we propose an agenda to further synergistic collaboration between computer science, law, and policy to advance the design of automated decision processes for accountabilit

    Increased expression of programmed death ligand 1 (PD-L1) in human pituitary tumors

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    PURPOSE: Subsets of pituitary tumors exhibit an aggressive clinical courses and recur despite surgery, radiation, and chemotherapy. Because modulation of the immune response through inhibition of T-cell checkpoints has led to durable clinical responses in multiple malignancies, we explored whether pituitary adenomas express immune-related biomarkers that could suggest suitability for immunotherapy. Specifically, programmed death ligand 1 (PD-L1) has emerged as a potential biomarker whose expression may portend more favorable responses to immune checkpoint blockade therapies. We thus investigated the expression of PD-L1 in pituitary adenomas. METHODS: PD-L1 RNA and protein expression were evaluated in 48 pituitary tumors, including functioning and non-functioning adenomas as well as atypical and recurrent tumors. Tumor infiltrating lymphocyte populations were also assessed by immunohistochemistry. RESULTS: Pituitary tumors express variable levels of PD-L1 transcript and protein. PD-L1 RNA and protein expression were significantly increased in functioning (growth hormone and prolactin-expressing) pituitary adenomas compared to non-functioning (null cell and silent gonadotroph) adenomas. Moreover, primary pituitary adenomas harbored higher levels of PD-L1 mRNA compared to recurrent tumors. Tumor infiltrating lymphocytes were observed in all pituitary tumors and were positively correlated with increased PD-L1 expression, particularly in the functional subtypes. CONCLUSIONS: Human pituitary adenomas harbor PD-L1 across subtypes, with significantly higher expression in functioning adenomas compared to non-functioning adenomas. This expression is accompanied by the presence of tumor infiltrating lymphocytes. These findings suggest the existence of an immune response to pituitary tumors and raise the possibility of considering checkpoint blockade immunotherapy in cases refractory to conventional management
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