204 research outputs found

    Predictability of repeating earthquakes near Parkfield, California

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    We analyse sequences of repeating microearthquakes that were identified by applying waveform coherency methods to data from the Parkfield High-Resolution Seismic Network. Because by definition all events in a sequence have similar magnitudes and locations, the temporal behaviour of these sequences is naturally isolated, which, coupled with the high occurrence rates of small events, makes these data ideal for studying interevent time distributions. To characterize the temporal predictability of these sequences, we perform retrospective forecast experiments using hundreds of earthquakes. We apply three variants of a simple algorithm that produces sequence-specific, time-varying hazard functions, and we find that the sequences are predictable. We discuss limitations of these data and, more generally, challenges in identifying repeating events, and we outline the potential implications of our results for understanding the occurrence of large earthquake

    Discovery of the brightest T dwarf in the northern hemisphere

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    We report the discovery of a bright (H=12.77) brown dwarf designated SIMP J013656.5+093347. The discovery was made as part of a near-infrared proper motion survey, SIMP (Sondage Infrarouge de Mouvement Propre), which uses proper motion and near-infrared/optical photometry to identify brown dwarf candidates. A low resolution (lambda/dlambda~40) spectrum of this brown dwarf covering the 0.88-2.35 microns wavelength interval is presented. Analysis of the spectrum indicates a spectral type of T2.5+/-0.5. A photometric distance of 6.4+/-0.3 pc is estimated assuming it is a single object. Current observations rule out a binary of mass ratio ~1 and separation >5 AU. SIMP 0136 is the brightest T dwarf in the northern hemisphere and is surpassed only by Eps Indi Bab over the whole sky. It is thus an excellent candidate for detailed studies and should become a benchmark object for the early-T spectral class.Comment: 4 pages, 3 figures, To be published in November 1, 2006 issue of ApJL. Following IAU recommendation, the survey acronym (IBIS) was changed to SIM

    Postseismic variations in seismic moment and recurrence interval of repeating earthquakes

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    In laboratory experiments, longer stationary contact time leads to larger seismic moment during repeated ruptures. However, not all observations in natural fault systems agree with the prediction. We analyze a subset of 34 M−0.4–2.1 repeating earthquake sequences (RES) from 1987 to 2009 at Parkfield to examine the variation of their recurrence properties in space and time. Following a 2004 M6 earthquake, many of the repeating events have greatly reduced recurrence intervals (Tr) that systematically increase with time. In addition to this change in timing, we also find systematic changes in seismic moment (Mo), where most sequences experienced an immediate increase in Mo and subsequent decay as Tr approached pre-quake durations. The RES at shallower depth tend to have a larger range in both Tr and Mo, whereas deeper RES show smaller variation. The shallowest RES with the greatest magnitude (M1.8–2.1) among the events we studied reveal a large variation in Tr but small variation in Mo. These observations are qualitatively consistent with earthquake simulations in 3D continuum fault models with rate- and state-dependent friction. In the models, RES are produced on velocity-weakening patches surrounded by velocity-strengthening fault areas. The models show that the degree of postseismic variation in Mo and Tr is a function of radius (r) and nucleation zone size (h*) of the velocity-weakening patch. A ratio of r/h* ~ 1 produces negative Mo–Tr slopes, whereas larger ratios of r/h* yield weak positive slopes. Given the same nucleation size h* (i.e., the same frictional properties and effective normal stress), smaller radii and hence smaller seismic moments result in negative Mo–Tr slopes, whereas larger radii and hence larger moments lead to weak positive Mo–Tr slopes, which are consistent with observations. Conversely, with only a small percentage of its slip accumulated seismically, a small asperity appears to grow in Mo under high loading rate, which is contrary to the view that Mo should decrease due to a reduced strength recovery time

    Feeling the Beat: Bouncing Synchronization to Vibrotactile Music in Hearing and Early Deaf People

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    The ability to dance relies on the ability to synchronize movements to a perceived musical beat. Typically, beat synchronization is studied with auditory stimuli. However, in many typical social dancing situations, music can also be perceived as vibrations when objects that generate sounds also generate vibrations. This vibrotactile musical perception is of particular relevance for deaf people, who rely on non-auditory sensory information for dancing. In the present study, we investigated beat synchronization to vibrotactile electronic dance music in hearing and deaf people. We tested seven deaf and 14 hearing individuals on their ability to bounce in time with the tempo of vibrotactile stimuli (no sound) delivered through a vibrating platform. The corresponding auditory stimuli (no vibrations) were used in an additional condition in the hearing group. We collected movement data using a camera-based motion capture system and subjected it to a phase-locking analysis to assess synchronization quality. The vast majority of participants were able to precisely time their bounces to the vibrations, with no difference in performance between the two groups. In addition, we found higher performance for the auditory condition compared to the vibrotactile condition in the hearing group. Our results thus show that accurate tactile-motor synchronization in a dance-like context occurs regardless of auditory experience, though auditory-motor synchronization is of superior quality

    Messina: A Novel Analysis Tool to Identify Biologically Relevant Molecules in Disease

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    BACKGROUND: Morphologically similar cancers display heterogeneous patterns of molecular aberrations and follow substantially different clinical courses. This diversity has become the basis for the definition of molecular phenotypes, with significant implications for therapy. Microarray or proteomic expression profiling is conventionally employed to identify disease-associated genes, however, traditional approaches for the analysis of profiling experiments may miss molecular aberrations which define biologically relevant subtypes. METHODOLOGY/PRINCIPAL FINDINGS: Here we present Messina, a method that can identify those genes that only sometimes show aberrant expression in cancer. We demonstrate with simulated data that Messina is highly sensitive and specific when used to identify genes which are aberrantly expressed in only a proportion of cancers, and compare Messina to contemporary analysis techniques. We illustrate Messina by using it to detect the aberrant expression of a gene that may play an important role in pancreatic cancer. CONCLUSIONS/SIGNIFICANCE: Messina allows the detection of genes with profiles typical of markers of molecular subtype, and complements existing methods to assist the identification of such markers. Messina is applicable to any global expression profiling data, and to allow its easy application has been packaged into a freely-available stand-alone software package

    Ancient DNA Suggests Dwarf and ‘Giant’ Emu Are Conspecific

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    ) is unclear. King Island Emu were mainly distinguished by their much smaller size and a reported darker colour compared to modern Emu. oxidase subunit I (COI) region (1,544 bp), as well as a region of the melanocortin 1 receptor gene (57 bp) were sequenced using a multiplex PCR approach. The results show that haplotypes for King Island Emu fall within the diversity of modern Emu.These data show the close relationship of these emu when compared to other congeneric bird species and indicate that the King Island and modern Emu share a recent common ancestor. King Island emu possibly underwent insular dwarfism as a result of phenotypic plasticity. The close relationship between the King Island and the modern Emu suggests it is most appropriate that the former should be considered a subspecies of the latter. Although both taxa show a close genetic relationship they differ drastically in size. This study also suggests that rates of morphological and neutral molecular evolution are decoupled

    Genome-wide association study identifies peanut allergy-specific loci and evidence of epigenetic mediation in US children

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    Food allergy (FA) affects 2%-10% of US children and is a growing clinical and public health problem. Here we conduct the first genome-wide association study of well-defined FA, including specific subtypes (peanut, milk and egg) in 2,759 US participants (1,315 children and 1,444 parents) from the Chicago Food Allergy Study, and identify peanut allergy (PA)-specific loci in the HLA-DR and -DQ gene region at 6p21.32, tagged by rs7192 (P=5.5 × 10 -8) and rs9275596 (P=6.8 × 10 -10), in 2,197 participants of European ancestry. We replicate these associations in an independent sample of European ancestry. These associations are further supported by meta-analyses across the discovery and replication samples. Both single-nucleotide polymorphisms (SNPs) are associated with differential DNA methylation levels at multiple CpG sites (

    Low-Cost Precursors to Novel Hydrogen Storage Materials

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    From 2005 to 2010, The Dow Chemical Company (formerly Rohm and Haas Company) was a member of the Department of Energy Center of Excellence on Chemical Hydrogen Storage, which conducted research to identify and develop chemical hydrogen storage materials having the potential to achieve DOE performance targets established for on-board vehicular application. In collaboration with Center co-leads Los Alamos National Laboratory (LANL) and Pacific Northwest National Laboratory (PNNL), and other Center partners, Dow's efforts were directed towards defining and evaluating novel chemistries for producing chemical hydrides and processes for spent fuel regeneration. In Phase 1 of this project, emphasis was placed on sodium borohydride (NaBH{sub 4}), long considered a strong candidate for hydrogen storage because of its high hydrogen storage capacity, well characterized hydrogen release chemistry, safety, and functionality. Various chemical pathways for regenerating NaBH{sub 4} from spent sodium borate solution were investigated, with the objective of meeting the 2010/2015 DOE targets of 2−3/galgasolineequivalentatthepump(2-3/gal gasoline equivalent at the pump (2-3/kg H{sub 2}) for on-board hydrogen storage systems and an overall 60% energy efficiency. With the September 2007 No-Go decision for NaBH{sub 4} as an on-board hydrogen storage medium, focus was shifted to ammonia borane (AB) for on-board hydrogen storage and delivery. However, NaBH{sub 4} is a key building block to most boron-based fuels, and the ability to produce NaBH{sub 4} in an energy-efficient, cost-effective, and environmentally sound manner is critical to the viability of AB, as well as many leading materials under consideration by the Metal Hydride Center of Excellence. Therefore, in Phase 2, research continued towards identifying and developing a single low-cost NaBH4 synthetic route for cost-efficient AB first fill, and conducting baseline cost estimates for first fill and regenerated AB using a variety of synthetic routes. This project utilized an engineering-guided R&D approach, which involved the rapid down-selection of a large number of options (chemical pathways to NaBH{sub 4}) to a smaller, more manageable number. The research began by conducting an extensive review of the technical and patent literature to identify all possible options. The down-selection was based on evaluation of the options against a set of metrics, and to a large extent occurred before experimentation was initiated. Given the vast amount of literature and patents that has evolved over the years, this approach helped to focus efforts and resources on the options with the highest technical and commercial probability of success. Additionally, a detailed engineering analysis methodology was developed for conducting the cost and energy-efficiency calculations. The methodology utilized a number of inputs and tools (Aspen PEA{trademark}, FCHTool, and H2A). The down-selection of chemical pathways to NaBH{sub 4} identified three options that were subsequently pursued experimentally. Metal reduction of borate was investigated in Dow's laboratories, research on electrochemical routes to NaBH{sub 4} was conducted at Pennsylvania State University, and Idaho National Laboratory researchers examined various carbothermal routes for producing NaBH{sub 4} from borate. The electrochemical and carbothermal studies did not yield sufficiently positive results. However, NaBH{sub 4} was produced in high yields and purities by an aluminum-based metal reduction pathway. Solid-solid reactive milling, slurry milling, and solution-phase approaches to metal reduction were investigated, and while both reactive milling and solution-phase routes point to fully recyclable processes, the scale-up of reactive milling processes to produce NaBH{sub 4} is expected to be difficult. Alternatively, a low-cost solution-phase approach to NaBH{sub 4} has been identified that is based on conventional process unit operations and should be amenable to scale-up. Numerous advances in AB synthesis have been made in recent years to improve AB yields and purities. Process analysis of several leading routes to AB (Purdue's formate-based metathesis route and PNNL's NH{sub 4}BH{sub 4}-based route) indicated the cost to produce first-fill AB to be on the order of 9−10/kgAB,assumingaNaBHsub4costof9-10/kg AB, assuming a NaBH{sub 4} cost of 5/kg for a 10,000 metric tons/year sized AB plant. The analysis showed that the dominant cost component for producing first-fill AB is the cost of the NaBH4 raw material. At this AB cost and assuming 2.5 moles hydrogen released per mole of AB, it may be possible to meet DOE's 2010 storage system cost target, but the 2015 target will likely require lower cost AB and demonstrates the importance of having a low-cost route to NaBH{sub 4}. Substantial progress has also been made to define feasible pathways for the regeneration of spent ammonia borane fuel

    Sensory Communication

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    Contains table of contents on Section 2, an introduction, reports on eleven research projects and a list of publications.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Grant 5 R01 DC00270National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Grant 5 R01 DC00100National Institutes of Health Contract 7 R29 DC00428National Institutes of Health Grant 2 R01 DC00126U.S. Air Force - Office of Scientific Research Grant AFOSR 90-0200U.S. Navy - Office of Naval Research Grant N00014-90-J-1935National Institutes of Health Grant 5 R29 DC00625U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-181
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