Late Holocene environmental variability in the upper San Francisco Estuary as reconstructed from tidal marsh sediments

EXTRACT (SEE PDF FOR FULL ABSTRACT): Tidal marsh sediments collected from Browns Island in the lower Sacramento/San Joaquin Delta, California, are used to reconstruct environmental variability over the past 6.8 ka. Calibrated radiocarbon dates provide chronostratigraphic control. Trace metal analyses, grain-size variability, organic content, and macrofossils are used to define short- and long-term variations in relative salinity and inundation frequency. Aggradation began in subtidal fresh water conditions about 6.8 ka. Subtidal aggradation of clayey silts continued until about 6.3 ka, when conditions shifted toward a lower intertidal brackish marsh environment. By 5.1 ka, a brackish marsh plain had evolved, with surface water freshening after 4.1 ka. Conditions returned to brackish similar to the present after 2.3 ka

HEALTHY COMMAND ENVIRONMENTS: DEFINITIONS, RISK FACTORS, AND PROTECTIVE FACTORS

This project aims to identify protective and risk factors that contribute to a healthy command environment and the effects of those factors on Sailor behavior. To examine which factors were most impactful for building a healthy command environment, we developed and asked our participants a series of Likert scale questions and open-ended questions. Using their answers, we analyzed any perceived effects upon Sailor behavior. We compared responses from sea vs. shore command experiences as well as responses from different communities within the Navy. Our research shows which command practices, policies, procedures, and processes (P4) contributed to healthier environments. Our research shows that trust, leadership, and communication significantly influence a command’s environment. Our findings indicate that these themes can manifest through a variety of programs, policies, practices, and procedures. As a result, we recommend expanding the current leadership curriculum to include organizational behavior to improve implementation of the P4 throughout the military. We also recommend expanding the data collection effort throughout the Navy to gain a more complete understanding of healthy environments in the fleet and to enhance readiness, foster healthier Sailor behaviors, and encourage higher retention.N17Lieutenant, United States NavyCaptain, United States Marine CorpsLieutenant, United States NavyApproved for public release. Distribution is unlimited

Temperature calculation for linear induction motor in transport application with multiphysics approach

The article describes the implementation of the mathematical model of the interrelated electromechanical and thermal processes in a linear induction motor using simulation software MATLAB-Simulink. The developed model consists of electromechanical model, thermal model and cooling system (hydraulic) model which all affect each other. Temperature calculations of the traction single-sided linear induction motor for urban transportation system are performed for different regimes. The calculation results using the developed thermal model based on the thermal detailed equivalent circuit demonstrate a close concurrence with the finite element model, temperature values differ less than in 3.8-4.8%. Safe operation range for a traction linear induction motor was determined taking into account the uneven longitudinal heating using different variants of cooling systems and coolant flow values. Recommendations on their selection were formulated. Based on the calculations and following experimental testing it was determined that operation with the maximum load with current of 270 A and load force of 8,000 N is possible with the cooling air flow rate of at least 2.2 m3/s. © Published under licence by IOP Publishing Ltd

Analysis of the Payback Period of a Modernized Pump Unit with Induction Electric Motors of Advanced Energy Efficiency Classes

Aim. The comparative analysis of energy consumption, electricity costs during lifetime cycle and payback period of a pump unit with 90 kW 2-pole induction motors, belonging to various energy efficiency classes, feeding directly from power grid. Methods. The examined operating modes aligned with a typical operating cycle of a pump unit with approximately constant flow rate of 75-110 % of the rated flow. The calculations were based on the pump and induction motors nameplate data, which, in their turn, were based on the manufacturers’ experimental data. Results. The calculations of energy consumption, electricity costs and payback periods of a pump unit with 90 kW 2-pole induction motors, feeding directly from power grid have been performed in the article. The application of induction motors belonging to IE2, IE3 and IE4 energy efficiency classes has been discussed. Practical value. It has been demonstrated, than in case of replacement of an induction motor of energy efficiency class IE2 due to planned retrofit, payback period for an IE4 induction motor is 2.18 years, energy savings within a calculated 20-year operating period are 268MW·h, which makes €41110 in money terms. under the same conditions, the replacement of an induction motor of energy efficiency class IE2 with an induction motor of energy efficiency class IE3 will allow to save 88 MW·h within a calculated operating period, which, expressed in monetary terms, is €13500 and the payback period is 5.11 years. Thus, the article proves that despite a higher initial price, the choice of an induction motor of energy efficiency class IE4 tends to be more economically advantageous. © 2021, National Technical University "Kharkiv Polytechnic Institute". All rights reserved.Acknowledgment. The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2020-0060)

Twelve thousand years of dust: The Holocene global dust cycle constrained by natural archives

Mineral dust plays an important role in the climate system by interacting with radiation, clouds, and biogeochemical cycles. In addition, natural archives show that the dust cycle experienced variability in the past in response to global and local climate change. The compilation of the DIRTMAP paleodust datasets in the last two decades provided a target for paleoclimate models that include the dust cycle, following a time slice approach. We propose an innovative framework to organize a paleodust dataset that moves on from the positive experience of DIRTMAP and takes into account new scientific challenges, by providing a concise and accessible dataset of temporally resolved records of dust mass accumulation rates and particle grain-size distributions. We consider data from ice cores, marine sediments, loess/paleosol sequences, lake sediments, and peat bogs for this compilation, with a temporal focus on the Holocene period. This global compilation allows investigation of the potential, uncertainties and confidence level of dust mass accumulation rates reconstructions, and highlights the importance of dust particle size information for accurate and quantitative reconstructions of the dust cycle. After applying criteria that help to establish that the data considered represent changes in dust deposition, 43 paleodust records have been identified, with the highest density of dust deposition data occurring in the North Atlantic region. Although the temporal evolution of dust in the North Atlantic appears consistent across several cores and suggest that minimum dust fluxes are likely observed during the Early to mid-Holocene period (6000–8000 years ago), the magnitude of dust fluxes in these observations is not fully consistent, suggesting that more work needs to be done to synthesize datasets for the Holocene. Based on the data compilation, we used the Community Earth System Model to estimate the mass balance and variability of the global dust cycle during the Holocene, with dust load ranging from 17.1 to 20.5 Tg between 2000 and 10 000 years ago, and a minimum in the Early to Mid-Holocene (6000–8000 years ago)

A Multiproxy Database of Western North American Holocene Paleoclimate Records

Holocene climate reconstructions are useful for understanding the diverse features and spatial heterogeneity of past and future climate change. Here we present a database of western North American Holocene paleoclimate records. The database gathers paleoclimate time series from 184 terrestrial and marine sites, including 381 individual proxy records. The records span at least 4000 of the last 12 000 years (median duration of 10 725 years) and have been screened for resolution, chronologic control, and climate sensitivity. Records were included that reflect temperature, hydroclimate, or circulation features. The database is shared in the machine readable Linked Paleo Data (LiPD) format and includes geochronologic data for generating site-level time-uncertain ensembles. This publicly accessible and curated collection of proxy paleoclimate records will have wide research applications, including, for example, investigations of the primary features of ocean-atmospheric circulation along the eastern margin of the North Pacific and the latitudinal response of climate to orbital changes. The database is available for download at https://doi.org/10.6084/m9.figshare.12863843.v1 (Routson and McKay, 2020)

Hearing loss and cognition: A protocol for ensuring speech understanding before neurocognitive assessment

INTRODUCTION: Many neurocognitive evaluations involve auditory stimuli, yet there are no standard testing guidelines for individuals with hearing loss. The ensuring speech understanding (ESU) test was developed to confirm speech understanding and determine whether hearing accommodations are necessary for neurocognitive testing. METHODS: Hearing was assessed using audiometry. The probability of ESU test failure by hearing status was estimated in 2679 participants (mean age: 81.4 ± 4.6 years) using multivariate logistic regression. RESULTS: Only 2.2% (N = 58) of participants failed the ESU test. The probability of failure increased with hearing loss severity; similar results were observed for those with and without mild cognitive impairment or dementia. DISCUSSION: The ESU test is appropriate for individuals who have variable degrees of hearing loss and cognitive function. This test can be used prior to neurocognitive testing to help reduce the risk of hearing loss and compromised auditory access to speech stimuli causing poorer performance on neurocognitive evaluation