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Concept: Four Corners


The 13th century Puebloan depopulation of the Four Corners region of the US Southwest is an iconic episode in world prehistory. Studies of its causes, as well as its consequences, have a bearing not only on archaeological method and theory, but also social responses to climate change, the sociology of social movements, and contemporary patterns of cultural diversity. Previous research has debated the demographic scale, destinations, and impacts of Four Corners migrants. Much of this uncertainty stems from the substantial differences in material culture between the Four Corners vs. hypothesized destination areas. Comparable biological evidence has been difficult to obtain due to the complete departure of farmers from the Four Corners in the 13th century CE and restrictions on sampling human remains. As an alternative, patterns of genetic variation among domesticated species were used to address the role of migration in this collapse. We collected mitochondrial haplotypic data from dog (Canis lupus familiaris) and turkey (Meleagris gallopavo) remains from archaeological sites in the most densely-populated portion of the Four Corners region, and the most commonly proposed destination area for that population under migration scenarios. Results are consistent with a large-scale migration of humans, accompanied by their domestic turkeys, during the 13th century CE. These results support scenarios that suggest contemporary Pueblo peoples of the Northern Rio Grande are biological and cultural descendants of Four Corners populations.

Concepts: Puebloan peoples, DNA, Arizona, Wild Turkey, Population, Dog, Four Corners, Archaeology


Methane (CH4) impacts climate as the second strongest anthropogenic greenhouse gas and air quality by influencing tropospheric ozone levels. Space-based observations have identified the Four Corners region in the Southwest United States as an area of large CH4 enhancements. We conducted an airborne campaign in Four Corners during April 2015 with the next-generation Airborne Visible/Infrared Imaging Spectrometer (near-infrared) and Hyperspectral Thermal Emission Spectrometer (thermal infrared) imaging spectrometers to better understand the source of methane by measuring methane plumes at 1- to 3-m spatial resolution. Our analysis detected more than 250 individual methane plumes from fossil fuel harvesting, processing, and distributing infrastructures, spanning an emission range from the detection limit [Formula: see text] 2 kg/h to 5 kg/h through [Formula: see text] 5,000 kg/h. Observed sources include gas processing facilities, storage tanks, pipeline leaks, and well pads, as well as a coal mine venting shaft. Overall, plume enhancements and inferred fluxes follow a lognormal distribution, with the top 10% emitters contributing 49 to 66% to the inferred total point source flux of 0.23 Tg/y to 0.39 Tg/y. With the observed confirmation of a lognormal emission distribution, this airborne observing strategy and its ability to locate previously unknown point sources in real time provides an efficient and effective method to identify and mitigate major emissions contributors over a wide geographic area. With improved instrumentation, this capability scales to spaceborne applications [Thompson DR, et al. (2016) Geophys Res Lett 43(12):6571-6578]. Further illustration of this potential is demonstrated with two detected, confirmed, and repaired pipeline leaks during the campaign.

Concepts: Fossil fuel, Four Corners, Methane, Global warming, Carbon dioxide, Coal, Natural gas, Greenhouse gas


We propose a new olfactory display system that can generate an odor distribution on a two-dimensional display screen. The proposed system has four fans on the four corners of the screen. The airflows that are generated by these fans collide multiple times to create an airflow that is directed towards the user from a certain position on the screen. By introducing odor vapor into the airflows, the odor distribution is as if an odor source had been placed onto the screen. The generated odor distribution leads the user to perceive the odor as emanating from a specific region of the screen. The position of this virtual odor source can be shifted to an arbitrary position on the screen by adjusting the balance of the airflows from the four fans. Most users do not immediately notice the odor presentation mechanism of the proposed olfactory display system because the airflow and perceived odor come from the display screen rather than the fans. The airflow velocity can even be set below the threshold for airflow sensation, such that the odor alone is perceived by the user. We present experimental results that show the airflow field and odor distribution that are generated by the proposed system. We also report sensory test results to show how the generated odor distribution is perceived by the user and the issues that must be considered in odor presentation.

Concepts: Olfactory bulb, Four Corners, Taste, Electronic nose, Olfactory fatigue, Odor, Olfaction, Sense


Building on a history of collaboration in environmental public health and biomonitoring activities, laboratory and environmental epidemiology leaders in Arizona, Colorado, New Mexico, and Utah created the Four Corners States Biomonitoring Consortium, which is now in its third year of activities. In this article, we briefly highlight some lessons learned during the implementation phases of the consortium, including the processes of collaborating to identify common environmental exposure concerns, prioritizing those concerns, identifying cohorts and communities with potential risks of excessive exposure, developing a model for conducting exposure investigations, and the challenges presented during the implementation phases and early fieldwork activities. Detailed information on these topics can be found at The advantages of collaborating with, and leveraging the resources of, state Environmental Public Health Tracking Networks and Public Health Emergency Preparedness programs are discussed. Using one example from the early stages of this work, we also discuss the potential of biomonitoring as a vehicle for empowering the public to make informed choices to control their exposures and to influence public health decisions, support science-based environmental health policy and program development, and respond to emerging environmental exposure concerns.

Concepts: Health economics, Environmental health, Health, Public health, Utah, Four Corners, Arizona, Epidemiology


Methane (CH4) is a potent greenhouse gas and the primary component of natural gas. The San Juan Basin (SJB) is one of the largest coal-bed methane producing regions in North America and, including gas production from conventional and shale sources, contributes ~2% of U.S. natural gas production in 2015. In this work, we quantify the CH4 flux from the SJB using continuous atmospheric sampling from aircraft collected during the TOPDOWN2015 field campaign in April 2015. Using five independent days of measurements and the aircraft-based mass balance method, we calculate an average CH4 flux of 0.54 ± 0.20 Tg yr-1 (1σ), in close agreement with the previous space-based estimate made for 2003-2009. These results agree within error with the US EPA gridded inventory for 2012. These flights combined with the previous satellite study suggests CH4 emissions have not changed. While there have been significant declines in natural gas production between measurements, recent increases in oil production in the SJB may explain why emission of CH4 has not declined. Airborne quantification of outcrops where seepage occurs are consistent with ground-based studies that indicate these geological sources are a small fraction of the basin total (0.02-0.12 Tg yr-1) and cannot explain basin-wide consistent emissions from 2003-2015.

Concepts: Coalbed methane, Coal, Four Corners, Petroleum, Carbon dioxide, Greenhouse gas, Methane, Natural gas


Measurement of the displacement of the center-of-pressure (COP) is an important tool used in biomechanics to assess postural stability and human balance. The goal of this research was to design and validate a low-cost portable device that can offer a quick indication of the state of postural stability and human balance related conditions. Approximate entropy (ApEn) values reflecting the amount of irregularity hiding in COP oscillations were used to calculate the index. The prototype adopted a portable design using the measurements of the load cells located at the four corners of a low-cost force platform. The test subject was asked to stand on the device in a quiet, normal, upright stance for 30 s with eyes open and subsequently for 30 s with eyes closed. Based on the COP displacement signals, the ApEn values were calculated. The results indicated that the prototype device was capable of capturing the increase in regularity of postural control in the visual-deprivation conditions. It was also able to decipher the subtle postural control differences along anterior-posterior and medial-lateral directions. The data analysis demonstrated that the prototype would enable the quantification of postural stability and thus provide a low-cost portable device to assess many conditions related to postural stability and human balance such as aging and pathologies.

Concepts: Irregular, Validation, Four Corners, Regular, The Cop, Measurement, Measuring instrument, Biomechanics


In the present study, a novel intermittent badminton endurance test (B-ENDURANCE) was developed and tested in elite (n=17) and skilled (n=9) badminton players as well as in age-matched physically active men (non-badminton players; n=8). In addition, B-ENDURANCE test-retest reproducibility was evaluated in nine badminton players.B-ENDURANCE is an incremental test where each level consists of repeated sequences of badminton specific actions towards the four corners on the court. The subject starts in the center of the court in front of a computer screen and within each sequence he must in a randomized order complete eight actions as dictated by the computer providing the audiovisual input and verifying that the appropriate sensor is activated within the allocated time. Recovery time between each sequence is 10 seconds throughout the test, but the time to complete each sequence is gradually decreases until the subjects cannot follow the dictated tempo.B-ENDURANCE performance for elite players was better (P<0.05) compared to the skilled players and non-badminton players. In addition, B-ENDURANCE performance correlated (r=0.8; P<0.0001) with elite players' national single ranking. Test-retest coefficient of variation was 7.9 % between the first two trials (i.e. without a familiarization trial), but reduced to 2.5 % when comparing the 2 and 3 trial. In conclusion, the B-ENDURANCE test is relevant for evaluation of badminton specific endurance, but at least one familiarization trial is recommended if the test is used for evaluation of longitudinal changes, e.g. tracking training effects.

Concepts: Jury, England, Four Corners, Sequence, Badminton, United Kingdom, Present, Time


Boundaries are fundamental features that define a scene. However, not all boundaries are equally effective for navigation. For example, when preschoolers are disoriented and have to reorient by a flat boundary (e.g., a mat), they are unable to use geometry and will randomly search the four corners of the mat. However, when the mat is replaced by a curb 2 cm in height, they demonstrate geometric sensitivity by constraining their searches to the correct corner and its rotational equivalent (Lee & Spelke, 2011). This highlights children’s exceptional sensitivity to boundaries that create subtle alterations in geometry. In the present study, we ask whether this sensitivity could be impaired by genetic defect using both behavioral and fMRI methods. Williams syndrome (WS) is a disorder resulting in abnormalities of hippocampal and parietal areas of the brain known to be involved in reorientation. WS children ages 4-12 years (n = 7) and adults ages 22-35 years (n = 5) were tested in three arrays defined by different boundary cues (mat, curb, and full wall). In contrast to typically developing (TD) children, both children and adults with WS randomly searched the 4 corners of the curb, and only geometrically reoriented within full walls. These data demonstrate that the WS reorientation mechanism is fragile, in that it requires the input of especially salient presentation of geometric layout. In a previous fMRI experiment (Ferrara & Park, VSS 2013), we found that the parahippocampal place area in TD adults is sensitive to the presence of a minimal curb cue in visually presented artificial scenes. Analyses of fMRI data from 2 WS adults indicate that this sensitivity is diminished. Collectively, this research suggests that damage to human parietal and hippocampal areas stemming from a genetic deficit can result in impairment of behavioral and neural representation of boundary cues. Meeting abstract presented at VSS 2015.

Concepts: Syndromes, Genetic disorders, Hippocampus, Cerebrum, Schizophrenia, Brain, Geometry, Four Corners


Rectangular DNA origami functionalized with thiols in each of the four corners immobilizes by self-assembly between lithographically patterned gold nanodots on a silicon oxide surface.

Concepts: Four Corners, Aluminium, Nanotechnology, Oxygen, Silicon dioxide


Abstract Iron (oxyhydr)oxide microbial mats in modern to ∼100 ka tufa terraces are present in a cold spring system along Ten Mile Graben, southeastern Utah, USA. Mats exhibit morphological, chemical, and textural biosignatures and show diagenetic changes that occur over millennial scales. The Jurassic Brushy Basin Member of the Morrison Formation in the Four Corners region of the USA also exhibits comparable microbial fossils and iron (oxyhydr)oxide biosignatures in the lacustrine unit. Both the modern spring system and Brushy Basin Member represent alkaline, saline, groundwater-fed systems and preserve diatoms and other similar algal forms with cellular elaboration. Two distinct suites of elements (1. C, Fe, As and 2. C, S, Se, P) are associated with microbial fossils in modern and ancient iron (oxyhydr)oxides and may be potential markers for biosignatures. The presence of ferrihydrite in ∼100 ka fossil microbial mats and Jurassic rocks suggests that this thermodynamically unstable mineral may also be a potential biomarker. One of the most extensive sedimentary records on Mars is exposed in Gale Crater and consists of non-acidic clays and sulfates possibly of lacustrine origin. These terrestrial iron (oxyhydr)oxide examples are a valuable analogue because of similar iron- and clay-rich host rock compositions and will help (1) understand diagenetic processes in a non-acidic, saline lacustrine environment such as the sedimentary rocks in Gale Crater, (2) document specific biomediated textures, (3) demonstrate how biomediated textures might persist or respond to diagenesis over time, and (4) provide a ground truth library of textures to explore and compare in extraterrestrial iron (oxyhydr)oxides, where future explorations hope to detect past evidence of life. Key Words: Biogeochemistry-Mars-Biosignatures-Diagenesis-Iron oxides. Astrobiology 14, xxx-xxx.

Concepts: Diagenesis, Water, Limestone, Sediment, Four Corners, Sedimentary rock, Rock, Fossil