1,131 research outputs found
A model-based reasoning approach to sensor placement for monitorability
An approach is presented to evaluating sensor placements to maximize monitorability of the target system while minimizing the number of sensors. The approach uses a model of the monitored system to score potential sensor placements on the basis of four monitorability criteria. The scores can then be analyzed to produce a recommended sensor set. An example from our NASA application domain is used to illustrate our model-based approach to sensor placement
WELFARE EFFECTS OF FISHERY POLICIES: NATIVE AMERICAN TREATY RIGHTS AND RECREATIONAL SALMON FISHING
Severe declines in Pacific Northwest salmon stocks, coupled with increasing recreational demands, and judicial decisions supporting Native American fishing rights create challenges for fishery agencies. This article explores the welfare effects on recreational anglers of alternative salmon allocation policies to meet Native American treaty rights. A discrete choice random utility model, coupled with a Poisson trip frequency model, is used to analyze these welfare effects. The model is fit to survey data from the Willamette River spring chinook fishery, an important recreational fishery in Oregon. Management options have dramatically different welfare effects.Resource /Energy Economics and Policy,
Power Corrections to the Universal Heavy WIMP-Nucleon Cross Section
WIMP-nucleon scattering is analyzed at order in Heavy WIMP Effective
Theory. The power corrections, where is the WIMP mass,
distinguish between different underlying UV models with the same universal
limit and their impact on direct detection rates can be enhanced relative to
naive expectations due to generic amplitude-level cancellations at leading
order. The necessary one- and two-loop matching calculations onto the
low-energy effective theory for WIMP interactions with Standard Model quarks
and gluons are performed for the case of an electroweak SU(2) triplet WIMP,
considering both the cases of elementary fermions and composite scalars. The
low-velocity WIMP-nucleon scattering cross section is evaluated and compared
with current experimental limits and projected future sensitivities. Our
results provide the most robust prediction for electroweak triplet Majorana
fermion dark matter direct detection rates; for this case, a cancellation
between two sources of power corrections yields a small total correction,
and a total cross section close to the universal limit for . For the SU(2) composite scalar, the corrections
introduce dependence on underlying strong dynamics. Using a leading chiral
logarithm evaluation, the total correction has a larger magnitude and
uncertainty than in the fermionic case, with a sign that further suppresses the
total cross section. These examples provide definite targets for future direct
detection experiments and motivate large scale detectors capable of probing to
the neutrino floor in the TeV mass regime.Comment: 12 pages, 4 figures; references added, XENONnT projection included,
version to appear in Physics Letters
Functional analyses of hTel2 and TRF2 deltaB: Insights Into the Role of a New DNA Damage Pathway and Homologous Recombination in Mammalian Telomere Function
Tel2 influences telomere length in S. cerevisiae and DNA-damage signaling in C. elegans. We found that endogenous human Tel2 (hTel2) localized in a diffuse, granular patter to the nuclei of human cells where it was enriched in PML nuclear bodies, but telomeres. Surprisingly, hTel2 also localized to centrosomes. Although hTe!2 did not detectably interact with telomeric proteins or telomeric chromatin, the overexpression untagged hTel2 resulted in the slow elongation of telomeres in HTC75 and SK-HEP-1 cells. Furthermore, hTel2 overexpression suppressed the accumulation of cells in G2 after ionizing radiation. The depletion of hTel2 in HeLa cells by RNA interference resulted in apoptotic cell death. Furthermore, hTel2 depletion resulted in the accumulation of aberrant mitotic cells that possessed disorganized metaphase chromosomes. The metaphase chromosomes of hTel2 depleted cells were curly suggesting that hTel2 played a role in chromosome compaction. A role for hTel2 in establishing chromatin structure during S-phase could explain its multiple localizations and phenotypes. TRF2 protects telomeres from non-homologous end joining (NHEJ), possibly through the formation of a t-loop structure. A mutant allele of TRF2, TRF2AB, retained the ability to suppress NHEJ but induced dramatic deletions of telomeric DNA. This catastrophic telomere shortening was accompanied by a DNA damage response and senescence. Using FISH and CO-FISH, TRF2AB was found to induce rapid, stochastic deletions that preferentially affected leading strand telomeres (parental C-strand) DNA replication. Genetic analyses demonstrated that TRF2AB-induced deletions required Nbsl, a component of the Mrell complex, and XRCC3, a component of the RAD51C/XRCC3 Holliday junction (HJ) resolvase, suggesting the involvement of homologous recombation (HR) in the deletions. Consistent with a role for HR, TRF2AB induced the formation of t-loop-sized telomeric circles. These telomeric circles were detected in unperturbed cells suggesting that t-loop deletion by H R could explain the stochastic nature of telomere shortening and senescence in somatic cells. Furthermore, telomerase-negative ALT cells had abundant telomeric circles, suggesting that recombination-mediated elongation of ALT telomeres could involve telomeric circles. These findings show that TRF2 regulates both NHEJ and HR at mammalian telomeres and that HR at telomeres influences the integrity and dynamics of mammalian telomeres
Attention focussing and anomaly detection in real-time systems monitoring
In real-time monitoring situations, more information is not necessarily better. When faced with complex emergency situations, operators can experience information overload and a compromising of their ability to react quickly and correctly. We describe an approach to focusing operator attention in real-time systems monitoring based on a set of empirical and model-based measures for determining the relative importance of sensor data
Liposome encapsulation of fluorescent nanoparticles: Quantum dots and silica nanoparticles
Quantum dots (QDs) and silica nanoparticles (SNs) are relatively new classes of fluorescent probes that overcome the limitations encountered by organic fluorophores in bioassay and biological imaging applications. We encapsulated QDs and SNs in liposomes and separated nanoparticle-loaded liposomes from unencapsulated nanoparticles by size exclusion chromatography. Fluorescence correlation spectroscopy was used to measure the average number of nanoparticles inside each liposome. Results indicated that nanoparticle-loaded liposomes were formed and separated from unencapsulated nanoparticles by using a Sepharose gel. As expected, fluorescence self-quenching of nanoparticles inside liposomes was not observed. Each liposome encapsulated an average of three QDs. These studies demonstrated that nanoparticles could be successfully encapsulated into liposomes and provided a methodology to quantify the number of nanoparticles inside each liposome by fluorescence correlation spectroscop
Collegiate Professional Pilot Programs: Acquisition and Use of a Level Six Training Device in the Academic Environment
Regardless of the bill of H. R. 5900 Airline Safety and Federal Aviation Administration Act of 201 0 aiming to elevate the flight hours and level of certification for pilots working for FAA FAR 121 air carriers, the ongoing pilot recruitment at regional airlines continues to grow. Simultaneously, an influx of low time and relatively inexperienced pilots are continuously flying the revenue passenger. In this case, collegiate aviation programs should take the responsibility to deliver low-time pilots, yet with sufficient knowledge and skills regarding multiple crew scenarios and complex transport aircraft systems. With this in mind, in order to ensure the quality and experience flight training at the university level, full size air carrier Flight Training Devices (FTD), and sometimes motion simulators (FFS Full flight Simulators) are used. However, the aforementioned high-end devices are not affordable to every collegiate aviation program. To make efficient use of the professional student pilot\u27s budget and ensure a thorough and comprehensive application of systems knowledge and crew resource management concepts, a compatible alternative is an option. In this paper, a Flight Training Device (FTD)/simulator was used and the certification process and acquisition steps were described. Due to the nature of the study, Action Research Methodology (ARM) was selected. The result showed that the selected complex training device could become a standard feature of a collegiate aviation program to equip professional pilot majors with sufficient knowledge in an intensive, commercial environment
ECLSS predictive monitoring
On Space Station Freedom (SSF), design iterations have made clear the need to keep the sensor complement small. Along with the unprecendented duration of the mission, it is imperative that decisions regarding placement of sensors be carefully examined and justified during the design phase. In the ECLSS Predictive Monitoring task, we are developing AI-based software to enable design engineers to evaluate alternate sensor configurations. Based on techniques from model-based reasoning and information theory, the software tool makes explicit the quantitative tradeoffs among competing sensor placements, and helps designers explore and justify placement decisions. This work is being applied to the Environmental Control and Life Support System (ECLSS) testbed at MSFC to assist design personnel in placing sensors for test purposes to evaluate baseline configurations and ultimately to select advanced life support system technologies for evolutionary SSF
Intelligent assistance in scientific data preparation
Scientific data preparation is the process of extracting usable scientific data from raw instrument data. This task involves noise detection (and subsequent noise classification and flagging or removal), extracting data from compressed forms, and construction of derivative or aggregate data (e.g. spectral densities or running averages). A software system called PIPE provides intelligent assistance to users developing scientific data preparation plans using a programming language called Master Plumber. PIPE provides this assistance capability by using a process description to create a dependency model of the scientific data preparation plan. This dependency model can then be used to verify syntactic and semantic constraints on processing steps to perform limited plan validation. PIPE also provides capabilities for using this model to assist in debugging faulty data preparation plans. In this case, the process model is used to focus the developer's attention upon those processing steps and data elements that were used in computing the faulty output values. Finally, the dependency model of a plan can be used to perform plan optimization and run time estimation. These capabilities allow scientists to spend less time developing data preparation procedures and more time on scientific analysis tasks
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