1,293 research outputs found
Automobile safety regulation : technological change and regulatory process
This report examines the history of automobile safety regulation since 1966, viewed as an attempt to substitute public decisions on the design of new automobiles for private decisions. The focus of the
examination is on the problems which confront regulators in the National Highway Traffic Safety Administration (NHTSA) in their attempt to affect the design and performance of automobiles and on the effect regulation
has actually had on automotive technology.
Congress gave the NHTSA two ways of bringing about changes in the design and performance of automobiles. The NHTSA may set mandatory
performance standards for automobiles and may conduct research and development on new automobile safety technology. Congress did not set a programmed goal that was to be achieved through these methods, however.
Instead, the NHTSA must continually decide in an ad hoc fashion the desirability of particular changes in the attributes of new cars. Those that it finds desirable must be forced into practice through standards.
The purpose of the agency's R&D is to make possible for the first time additional changes in vehicle attributes which the agency may then choose to force into practice as well.
Several inherent problems in developing the technical requirements in proposals for new standards and in judging the desirability of
proposals have not been fully resolved by the NHTSA. They have had a detrimental effect on the number and quality of standards promulgated since the initial set. The agency's efforts in developing new technology
have also faced problems and have so far not contributed to its standards. In order for regulatory action to be taken, policy decisions must be made to compensate for uncertainties in predictions of the impacts of. proposed standards. Policy decisions must also be made as to the desirable balance between reductions in traffic risks and increased costs. The uncertainties could be reduced if more reliance were placed
on large-scale experimental testing of contemplated safety modifications
in actual use. The policy choices that would remain, of both types, could be improved if they were recognized as such and the process for making them opened up to greater outside inspection and participation.Based upon research supported by Division of Policy Research and Analysis, National Science Foundation under Grant no. OEP 76-00284
Automatic Optical Image Stabilization System Calibration, Validation, and Performance for the SkySat Constellation
Capturing Earth imagery from low-Earth orbit causes blur from the spacecraft’s orbital motion. Planet’s high resolution SkySat satellites utilize an Optical Image Stabilization (OIS) system to reduce motion blur by mechanical oscillation of the payload assembly. Automated on-orbit procedures and analyses are used for calibration and validation of the system across a fleet of 19 satellites. OIS actuation settings are configured for each image capture through automated optimization procedures. The benefit of the OIS system is demonstrated by an increased collection ground scan rate with no degradation to image quality, thereby improving fleet production capacity of the SkySat constellation
Recognition of two distinct elements in the RNA substrate by the RNA-binding domain of the T. thermophilus DEAD box helicase Hera
DEAD box helicases catalyze the ATP-dependent destabilization of RNA duplexes. Whereas duplex separation is mediated by the helicase core shared by all members of the family, flanking domains often contribute to binding of the RNA substrate. The Thermus thermophilus DEAD-box helicase Hera (for “heat-resistant RNA-binding ATPase”) contains a C-terminal RNA-binding domain (RBD). We have analyzed RNA binding to the Hera RBD by a combination of mutational analyses, nuclear magnetic resonance and X-ray crystallography, and identify residues on helix α1 and the C-terminus as the main determinants for high-affinity RNA binding. A crystal structure of the RBD in complex with a single-stranded RNA resolves the RNA–protein interactions in the RBD core region around helix α1. Differences in RNA binding to the Hera RBD and to the structurally similar RBD of the Bacillus subtilis DEAD box helicase YxiN illustrate the versatility of RNA recognition motifs as RNA-binding platforms. Comparison of chemical shift perturbation patterns elicited by different RNAs, and the effect of sequence changes in the RNA on binding and unwinding show that the RBD binds a single-stranded RNA region at the core and simultaneously contacts double-stranded RNA through its C-terminal tail. The helicase core then unwinds an adjacent RNA duplex. Overall, the mode of RNA binding by Hera is consistent with a possible function as a general RNA chaperone
Recognition of two distinct elements in the RNA substrate by the RNA-binding domain of the T. thermophilus DEAD box helicase Hera
DEAD box helicases catalyze the ATP-dependent destabilization of RNA duplexes. Whereas duplex separation is mediated by the helicase core shared by all members of the family, flanking domains often contribute to binding of the RNA substrate. The Thermus thermophilus DEAD-box helicase Hera (for "heat-resistant RNA-binding ATPase”) contains a C-terminal RNA-binding domain (RBD). We have analyzed RNA binding to the Hera RBD by a combination of mutational analyses, nuclear magnetic resonance and X-ray crystallography, and identify residues on helix α1 and the C-terminus as the main determinants for high-affinity RNA binding. A crystal structure of the RBD in complex with a single-stranded RNA resolves the RNA-protein interactions in the RBD core region around helix α1. Differences in RNA binding to the Hera RBD and to the structurally similar RBD of the Bacillus subtilis DEAD box helicase YxiN illustrate the versatility of RNA recognition motifs as RNA-binding platforms. Comparison of chemical shift perturbation patterns elicited by different RNAs, and the effect of sequence changes in the RNA on binding and unwinding show that the RBD binds a single-stranded RNA region at the core and simultaneously contacts double-stranded RNA through its C-terminal tail. The helicase core then unwinds an adjacent RNA duplex. Overall, the mode of RNA binding by Hera is consistent with a possible function as a general RNA chaperon
Suffering from Whiplash? The Effects of Pencil Whipping on Data Variability in the Safety Industry
Big data is being used by organizations to identify trends and predict future safety incidents. However, analytics using big data relies heavily on data quality, which can be compromised by a lack of data variability. In the safety industry, the data reports most frequently analyzed include checklists that are filled out by managers and operators, and research is being attempted to link the variables from these reports to safety outcomes. A major obstacle is the reduced variability in these reports due to a phenomenon known as “pencil whipping.” Pencil whipping occurs when an employee completes a safety checklist during behavior-based safety observation without actually carrying out the work required (e.g., checking “safe” all the way down the checklist; Ludwig 2014). In order to run analyses that will create targeted interventions, organizations need to reduce pencil-whipping in their reports. This study will attempt to identify data markers of pencil whipping and will investigate the effects of pencil whipping on data variability and analysis
Morpheme Segmentation Gold Standards for Finnish and English
This document describes Hutmegs, the Helsinki University of Technology Morphological Evaluation Gold Standard package, which contains gold-standard morphological segmentations for 1.4 million Finnish and 120 000 English words. The Gold Standards comprise surface-string, or allomorph, segmentations of word forms, as well as deep-level, or morpheme, segmentations of the words.Non peer reviewe
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Design and testing of a control strategy for a large naturallyventilated office building
The design for the new Federal Building for San Franciscoincludes an office tower that is to be naturally ventilated. Each flooris designed to be cross-ventilated, through upper windows that arecontrolled by the building management system (BMS). Users have controlover lower windows, which can be as much as 50 percent of the totalopenable area. There are significant differences in the performance andthe control of the windward and leeward sides of the building, andseparate monitoring and control strategies are determined for each side.The performance and control of the building has been designed and testedusing a modified version of EnergyPlus. Results from studies withEnergyPlus and CFD are used in designing the control strategy. EnergyPluswas extended to model a simplified version of the airflow patterndetermined using CFD. Wind-driven cross-ventilation produces a main jetthrough the upper openings of the building, across the ceiling from thewindward to the leeward side. Below this jet, the occupied regions aresubject to a recirculating air flow. Results show that temperatureswithin the building are predicted to be satisfactory, provided a suitablecontrol strategy is implemented uses night cooling in periods of hotweather. The control strategy has 10 window opening modes. EnergyPlus wasextended to simulate the effects of these modes, and to assess theeffects of different forms of user behavior. The results show how userbehavior can significantly influence the buildingperformance
The relation between star formation, morphology and local density in high redshift clusters and groups
We investigate how the [OII] properties and the morphologies of galaxies in
clusters and groups at z=0.4-0.8 depend on projected local galaxy density, and
compare with the field at similar redshifts and clusters at low-z. In both
nearby and distant clusters, higher-density regions contain proportionally
fewer star-forming galaxies, and the average [OII] equivalent width of
star-forming galaxies is independent of local density. However, in distant
clusters the average current star formation rate (SFR) in star-forming galaxies
seems to peak at densities ~15-40 galaxies Mpc^{-2}. At odds with low-z
results, at high-z the relation between star-forming fraction and local density
varies from high- to low-mass clusters. Overall, our results suggest that at
high-z the current star formation (SF) activity in star-forming galaxies does
not depend strongly on global or local environment, though the possible SFR
peak seems at odds with this conclusion. We find that the cluster SFR
normalized by cluster mass anticorrelates with mass and correlates with the
star-forming fraction. These trends can be understood given a) that the average
star-forming galaxy forms about 1 Msun/yr in all clusters; b) that the total
number of galaxies scales with cluster mass and c) the dependence of
star-forming fraction on cluster mass. We present the morphology-density (MD)
relation for our z=0.4-0.8 clusters, and uncover that the decline of the spiral
fraction with density is entirely driven by galaxies of types Sc or later. For
galaxies of a given Hubble type, we see no evidence that SF properties depend
on local environment. In contrast with recent findings at low-z, in our distant
clusters the SF-density relation and the MD-relation are equivalent, suggesting
that neither of the two is more fundamental than the other.(abr.)Comment: 21 pages, 14 figures, accepted for publication in Ap
Chemoprevention of nonmelanoma skin cancer: experience with a polyphenol from green tea.
Nonmelanoma skin cancer is extremely common and is increasing in incidence. It would be very useful to have forms of therapy that would prevent precancerous changes from going on to form cancer, or to reverse the precancerous changes. Epidemiologic evidence in humans, in vitro studies on human cells, and clinical experiments in animals have identified polyphenol compounds found in tea to be possibly useful in reducing the incidence of various cancers, including skin cancer. To examine the potential for a polyphenol from green tea, epigallocatechin gallate, to act as a chemopreventive agent for nonmelanoma skin cancer, a randomized, double-blind, placebo-controlled phase II clinical trial of topical epigallocatechin gallate in the prevention of nonmelanoma skin cancer was performed
The International Surface Pressure Databank version 2
The International Surface Pressure Databank (ISPD) is the world's largest collection of global surface and sea-level pressure observations. It was developed by extracting observations from established international archives, through international cooperation with data recovery facilitated by the Atmospheric Circulation Reconstructions over the Earth (ACRE) initiative, and directly by contributing universities, organizations, and countries. The dataset period is currently 1768–2012 and consists of three data components: observations from land stations, marine observing systems, and tropical cyclone best track pressure reports. Version 2 of the ISPD (ISPDv2) was created to be observational input for the Twentieth Century Reanalysis Project (20CR) and contains the quality control and assimilation feedback metadata from the 20CR. Since then, it has been used for various general climate and weather studies, and an updated version 3 (ISPDv3) has been used in the ERA-20C reanalysis in connection with the European Reanalysis of Global Climate Observations project (ERA-CLIM). The focus of this paper is on the ISPDv2 and the inclusion of the 20CR feedback metadata. The Research Data Archive at the National Center for Atmospheric Research provides data collection and access for the ISPDv2, and will provide access to future versions
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