Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
This data set consists of raw multi-channel seismic reflection (MCS) data in SEG-Y format, collected in July 2022 along the continental slope of the Campeche Bank aboard R/V Justo Sierra. The research objective was to map the detailed stratigraphy of sediment drift deposits to explore the history of the Loop Current and its climatic implications. We used the portable high-resolution seismic acquisition system operated by Scripps Institution of Oceanography, which comprised a source array of two 45 cubic inches G.I. air-guns and a GeoEel streamer with 120 channels at a spacing of 6.25 m. The air-gun array was fired every 12.5 m and was towed at a depth of 3 m. Data was recorded using the Geometrics seismic recording system with sample rate of 0.5 ms and recording length of 4 ms. A 50-ms delay was created during each shot as a buffer between the timing pulse that starts the recording and the trigger pulse that fires the air-guns. A total of 11 seismic lines were acquired including two long strike lines, five dip lines, two tilted dip lines and two short transition lines. The shot spacing was not exactly 12.5 m during the first three lines (1001-1003) due to system glitches, therefore, it is necessary to merge navigation with SEG-Y headers to ensure accurate processing of these lines. Detailed acquisition parameters and cruise incidents are described in the associated documents. Funding for this work was provided through NSF awards OCE-1928888 and OCE-1450528, and CONTEX award 2018-38A.more » « less
-
Abstract Beyond our Solar System, aurorae have been inferred from radio observations of isolated brown dwarfs1,2. Within our Solar System, giant planets have auroral emission with signatures across the electromagnetic spectrum including infrared emission of H3+and methane. Isolated brown dwarfs with auroral signatures in the radio have been searched for corresponding infrared features, but only null detections have been reported3. CWISEP J193518.59-154620.3. (W1935 for short) is an isolated brown dwarf with a temperature of approximately 482 K. Here we report James Webb Space Telescope observations of strong methane emission from W1935 at 3.326 μm. Atmospheric modelling leads us to conclude that a temperature inversion of approximately 300 K centred at 1–10 mbar replicates the feature. This represents an atmospheric temperature inversion for a Jupiter-like atmosphere without irradiation from a host star. A plausible explanation for the strong inversion is heating by auroral processes, although other internal and external dynamical processes cannot be ruled out. The best-fitting model rules out the contribution of H3+emission, which is prominent in Solar System gas giants. However, this is consistent with rapid destruction of H3+at the higher pressure where the W1935 emission originates4.more » « less
-
Abstract Genetic connectivity lies at the heart of evolutionary theory, and landscape genetics has rapidly advanced to understand how gene flow can be impacted by the environment. Isolation by landscape resistance, often inferred through the use of circuit theory, is increasingly identified as being critical for predicting genetic connectivity across complex landscapes. Yet landscape impediments to migration can arise from fundamentally different processes, such as landscape gradients causing directional migration and mortality during migration, which can be challenging to address. Spatial absorbing Markov chains (SAMC) have been introduced to understand and predict these (and other) processes affecting connectivity in ecological settings, but the relationship of this framework to landscape genetics remains unclear. Here, we relate the SAMC to population genetics theory, provide simulations to interpret the extent to which the SAMC can predict genetic metrics and demonstrate how the SAMC can be applied to genomic data using an example with an endangered species, the Panama City crayfish Procambarus econfinae , where directional migration is hypothesized to occur. The use of the SAMC for landscape genetics can be justified based on similar grounds to using circuit theory, as we show how circuit theory is a special case of this framework. The SAMC can extend circuit‐theoretic connectivity modelling by quantifying both directional resistance to migration and acknowledging the difference between migration mortality and resistance to migration. Our empirical example highlights that the SAMC better predicts population structure than circuit theory and least‐cost analysis by acknowledging asymmetric environmental gradients (i.e. slope) and migration mortality in this species. These results provide a foundation for applying the SAMC to landscape genetics. This framework extends isolation‐by‐resistance modelling to account for some common processes that can impact gene flow, which can improve predicting genetic connectivity across complex landscapes.more » « less
-
The current state of math education at a tribal college / university, TCU, will be presented, particularly with respect to entry into STEM majors. The alternative developmental math curriculum offered at a TCU institution using a modified pedagogical delivery system offers sound mathematical principals based on life-skills with relevant problem-solving, while explicitly addressing other holistic needs of the student such as math anxiety, persistence, mindset, and the value of collaboration (group work). This cooperative work is intended to create a community of learning which is in tune with traditional Native American cultural practices. Students learn to be responsible for their learning, engage in team work, and develop a “can-do” attitude towards mathematics. Implementation of two separate approaches at two separate institutions will be presented.more » « less
-
Typically college STEM instructors implicitly expect a level of meta-cognition, emotional resiliency, and general student readiness that largely exceeds any training or preparation students receive in K-12. Not meeting such expectations is perhaps a more significant barrier to student success than deficits in subject-based knowledge. This paper discusses initiatives at Sitting Bull College that seek, without substantial curricular change, to enhance student meta-cognition and emotional intelligence through the use of contextualized & project-based learning in a cohort model that incorporates specific skills training (such as Motivational Interviewing) for both students and instructors.more » « less
An official website of the United States government

Full Text Available