bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of the Thermal Plumes in a Thick Layer Cooled From Above
Authors: Volino Ralph J. , Smith Geoffrey B. 
Published: March 2022

Abstract
Simultaneous measurements of surface temperature and the underlying velocity field are presented for a thick horizontal layer evaporatively cooled from above. The convection is characterized by meandering, descending sheet-like plumes which form where cool fluid at the surface collects and plunges into the warmer bulk fluid below. Previous studies have documented the temperature field at the cooled surface and a few have provided point measurements of velocity in the fluid below the surface, but simultaneous measurements of surface temperature and the velocity field were lacking. In the present study, the instantaneous, free surface temperature field has been documented with an infrared (IR) sensing camera. Simultaneous two-dimensional velocity measurements in planes perpendicular and parallel to the free surface were acquired using digital particle image velocimetry (DPIV). Data from cases using room temperature water with Ra* = 1.3 × 109, and heated water with Ra* = 8.5 × 109 are presented. In planes perpendicular to the free surface, velocities were quantified in the convective plumes and the surrounding fluid. The plumes were correlated with the low temperature lines in the free surface temperature field. The velocities in the plumes were about ten times those in the surrounding fluid. In planes parallel to the free surface, horizontal motions toward the descending sheets were observed and quantified. The present measurements provide needed documentation of the relationship between the surface temperature and the underlying hydrodynamics, that is, the velocity fields associated with the convective plumes.
Experiments on Czochralski Convection Model
Authors: Nakano Akifumi , Koyama Hide S. , Sung Hyung Jin 
Published: March 2022

Abstract
A laboratory experiment of critical transition flow modes in Czochralski convection model was performed. The time period of temperature oscillation tp and the interval of temperature oscillation ΔT were scrutinized to capture the critical transition regime. The effects of the rotation of a model crystal rod and a model crucible were examined for three Prandtl number flows (9.10 × 102, 4.45 × 103 and 8.89 × 103). Liquid crystal flow visualization was carried out. Experiment was extended to suppress the temperature oscillation by varying the rotation rate of model crystal rod Ω = Ω0 (1 + A sin (2πft/tp)), where A denotes the rotation amplitude and f the frequency. Based on the inherent time period of oscillation tp, the oscillatory flow modes were characterized in a range of mixed convection parameter 24.3 ≤ Ra/PrRe2 ≤ 950 at Rayleigh number Ra = 4.84 × 106.
All Angle-of-Attack Hydrodynamic Model for Underwater Vehicles Validated by Tank Test Data
Authors: Chhabra Narender K. , Scholten James R. 
Published: March 2022

Abstract
An underwater vehicle’s design and operation requires prediction of its performance at various velocities and angles-of-attack or of sideslip. Traditional models based upon headway motion at substantial speeds use coefficient-based equations of motion. Simulations based upon these coefficients are not valid for hover, low speeds, or high angles-of-attack or of sideslip.
To remedy this severe limitation, nonlinear hydrodynamic models valid for all attitudes of underwater vehicles have been developed and are presented here. These models are derived from the physics of hydrodynamic phenomena. Forces and moments for the total vehicle are obtained by relying on body-buildup techniques. For the vehicle’s hull, the models are profile drag, lift, crossflow force, and added mass. For appendages such as fins, the models are lift and drag when unstalled, normal force when stalled, transition between unstalled and stalled conditions, and hull interference effects. Whenever the equations contain parametric coefficients such as added-mass, drag, and lift, values are specified for all angles-of-attack and sideslip with a minimal use of empirical look-up tables. These models represent the state-of-the-art in low speed hydrodynamics at all angles-of-attack.
The hydrodynamic models presented here have been improved and validated by analysis and comparison with test data. Sub-scale versions of two different vehicles have been tested in tow-tanks at all angles-of-attack.
The models have been implemented in a C language computer code which runs at high speed with no iteration required. This code is utilized regularly in faster-than-real-time vehicle performance simulations.
Coupled Lagrangian-Eulerian Analysis of Submerged Shells Subjected to Ballistic Shock Waves
Authors: Lee M. , Shin Y. S. 
Published: March 2022

Abstract
The coupled Lagrangian-Eulerian analysis has been performed to investigate the transient fluid-structure interaction of underwater ballistic waves and submerged elastic spherical shells. The ballistic waves are formed when a high speed solid body strikes the water surface and penetrates underwater. With the validation of this approach, analyses are first conducted for the problems of an elastic shell subjected to an acoustic step wave. Then, a series of numerical simulations has been conducted using the ballistic waves which are defined from the pressure wave generation model.
Innovative Concepts in Diver Thermal Protection
Authors: Zoulias James B. , Nuckols M. L. 
Published: March 2022

Abstract
Passive methods of protecting a diver from cold exposures are constantly being sought as alternatives to active heating systems. All passive thermal protection techniques share one common advantage over their active heating counterparts; they have no requirement for energy storage or energy distribution. This advantage tends to make passive protection less complex and usually less expensive. Unfortunately in severe cold water, passive systems have customarily required divers to use thick, layered insulating garments worn beneath waterproof diving suits to reduce the loss of body heat to the surrounding cold water. These suits tend to be excessively bulky — inhibiting diver mobility; inherently buoyant — requiring 40–60 pounds of lead weights to make the diver neutrally buoyant; difficult to keep waterproof — an uncertainty that could fatally reduce the diver’s thermal protection during long duration missions; and only minimally effective in protecting the divers’ extremities. Even the best conventional drysuits have been found to be inadequate to meet the full requirements for long duration missions in near freezing waters.
The objective of the research reported in this paper has been to provide the diving community with improvements in thermal protection for long duration, cold water missions. The unconventional approach proposed here, the use of liquids as an insulating medium for divers’ suits, shows promise as a means of significantly surpassing the performance, and acceptable durations, of conventional drysuits. Laboratory testing of conceptual insulating concepts are reported.
Combustion System Design for a Stirling Engine Powered Diver Propulsion Vehicle
Authors: Potter Ian J. , Reader Graham T. , Clavelle Eric , Bowen Caroline E. , Gorin Steve 
Published: March 2022

Abstract
The selection and design of a power system for any form of underwater vehicle is an extremely complex and difficult task. The system must be capable of providing the vehicle with the required mission performance in terms of power and energy and also be volumetrically and gravimetrically compact.
When the vehicle to be used is a newly designed U.S. Navy Diver Propulsion Vehicle (DPV), other power system constraints are highlighted. These constraints include limited vehicle diameter, high performance operation, low power requirements, safety and a non-magnetic signature. Of the many power systems available, very few can fulfil the design criteria for the DPV. One system that can is the hydrocarbon fuelled Stirling engine — a dynamic heat engine using an external combustion system.
This paper describes the design of the combustion system for the Stirling engine powered DPV. Details are given of the design evaluation and the development of a combustion gas recirculation system to enable pure gaseous oxygen to be used as the combustion oxidant In addition, details are given of the restrictions imposed on component design and manufacture by the low vehicle power requirements.
Selection of an Engine and Power Source for a Low Signature Diver Propulsion Vehicle
Authors: Gorin Steven E. , Gavin William , Schreck David , Reader Graham T. , Potter Ian J. , Fauvel O. R. 
Published: March 2022

Abstract
The selection of an engine and power source for a small, one-man, diver propulsion vehicle (DPV) for potential use in a minefield is the topic of this paper. The stringent requirements of minimal magnetic and acoustic signatures, low detectability, diver safety, and operation in a wide range of environmental conditions prevented the use of standard engine configurations. Other system requirements include two man portability, 10 mile range, 2 knot minimum speed, variable speed control, multiple start/stop capability, 0–300 fsw depth range, 29 °F to 95 °F operating temperature range, and −40°F to 140°F storage temperature range.
Several different engine technologies were considered, including electric motors, internal combustion engines, external combustion engines, piezoelectric motors, magneto hydrodynamic engines, and pneumatic engines. Most contenders were quickly eliminated because of their magnetic and/or acoustic signatures. Diesel, Rankine, and Stirling engines were determined to be the best candidates.
Candidate power sources were also evaluated. These included batteries, fuel cells, nuclear, and chemical power. Many of these were eliminated because of the safety consideration and others were eliminated because of the incompatibility with the engine. Hydrocarbon combustion was chosen because of its high specific energy and compatibility with candidate engines.
Candidate engine and power source technologies were evaluated for their ability to meet system requirements. The Stirling engine and the hydrocarbon combustor were selected as the most promising technologies for engine and power source prototype development This paper discusses the reason for the selection of these technologies.
Does Physical Conditioning Influence Performance Attenuation and Recovery in Gaelic Football?
Authors: Daly Lorcan S. , Ó Catháin Ciarán , Kelly David T. 
Published: March 2022

Purpose: This study investigated the influence of components of fitness on measures of performance attenuation and recovery following Gaelic football match play. Methods: Measurements of players’ anthropometric characteristics, body composition, running speed, lower-body strength and power, blood lactate concentrations, running economy, and maximal aerobic capacity () were taken over 2 separate days 1 week prior to a competitive match. Creatine kinase, countermovement jump height, drop jump height, contact time, reactive strength index, and perceptual responses were tested prematch, at full time, 24 hours postmatch, and 48 hours postmatch. Results: Multiple components of fitness were associated with reduced performance attenuation and improved recovery responses (adjusted R2 = 9.8%–27.6%; P < .05). Players were divided into higher-standard and lower-standard (higher standard: 57.4 [4.2] mL·kg−1·min−1; lower standard: 45.3 [3.8] mL·kg−1·min−1) and relative squat (higher standard: 1.46 [0.11] 1-repetition-maximum kg·body mass−1; lower standard: 1.20 [0.08] 1-repetition-maximum kg·body mass−1) groups. After adjusting for prematch baseline differences, there were significant differences between groups in drop jump height at 24 hours postmatch (; P < .05) and countermovement jump height at 48 hours postmatch (; P < .05), where the lower-standard group displayed larger decrements. In addition, there were significant differences between relative squat groups at all postmatch time points in contact time (; P < .05) and reactive strength index (; P < .05) and in perceptual responses at 24 hours postmatch (; P < .05), where the lower-standard group expressed larger decrements. Conclusion: Coaches should prioritize the development of aerobic capacity and neuromuscular function as an effective method of reducing performance attenuation and enhancing recovery kinetics in Gaelic football.
Life with a field geologist: Improbable adventures on five continents
Authors: Alvarez* Milly 
Published: March 2022

ABSTRACT
As the wife and field assistant of geologist Walter Alvarez for the past 56 years, I have shared in adventures on five different continents. The quest to explore the history of our planet has given us insight and understanding of human history and culture as well. From the semi-arid Guajira desert of Colombia to the network of bike paths in Holland, to witnessing the September 1969 Revolution in Libya, from living in a medieval Italian hill town, visiting the Silk Road cities in Soviet Central Asia, participating in the plate tectonic revolution, helping found the Geological Observatory of Coldigioco, and continuing in the stimulating environment of the University of California, Berkeley, our lives have been rich in experiences. Linking it all together reminds us of the nearly infinite number of contingencies and decisions that shape each of our lives and contribute to our shared human history.
Oceanic productivity after the Cretaceous/Paleogene impact: Where do we stand? The view from the deep
Authors: Alegret Laia , Arreguín-Rodríguez Gabriela J. , Thomas Ellen 
Published: March 2022

ABSTRACT
More than four decades have passed since Walter Alvarez helped to bring mass extinctions to the attention of a broad audience and inspired extensive multidisciplinary research on a wide variety of topics ranging from the Cretaceous/Paleogene (K/Pg) and other impact events to astronomy, climate modeling, and the centuries-long debate on the extent to which apparent extinctions are a real phenomenon or due to incompleteness of the fossil record. Many questions about ecosystems in the aftermath of extinctions remain, and we summarize knowledge about an integral part of this discussion, i.e., oceanic productivity after the K/Pg mass extinction. We compiled new and published benthic foraminiferal data across the K/Pg boundary globally, at geographically and bathymetrically diverse sites, to contribute to the understanding of environmental consequences of the K/Pg impact through analysis of extinction patterns in Earth’s largest habitat: the deep seafloor.
We find no significant links between the severity of extinction of benthic foraminiferal species or their global decrease in diversity and factors such as the distance from the Chicxulub crater, paleo-water depth, and paleolatitude. Benthic foraminiferal populations show strong post-impact variability in space and time, supporting the hypothesis of heterogeneous oceans with extensive, local-to-regional plankton blooms, but we suggest that the apparent geographic variability may at least in part be due to incompleteness of the geological record at high time resolution. Additional high-resolution studies are necessary to enable us to evaluate the rates of past extinctions and compare these to the rates of present and future extinctions.
Association between Olympic Games and children’s growth: evidence from China
Authors: Guo Chao , Hu Xiyuan , Xu Chaofan , Zheng Xiaoying 
Published: March 2022

ObjectivesTo estimate the association between the 2008 Beijing Olympic Games (BOG) and growth of children in China.MethodsA total sample of 6 951 children aged 3–10 years were included, among which 3 201 were interviewed in 2014 and 3 750 were interviewed in 2018. The BOG was used as a natural experiment. Exposure to the BOG was established by triple differences measured by age group, survey period and whether child participants were living in BOG areas or not, respectively. Children’s growth was assessed by binary variables of stunting, underweight, overweight and obesity. The difference-in-difference-in-differences (DDD) method was used to estimate the association between the BOG and children’s growth.ResultsDDD estimates showed that the BOG was significantly associated with decreased risks of children’s underweight (OR 0.12; 95% CI 0.02 to 0.69) and overweight (OR 0.43; 95% CI 0.19 to 0.98) after controlling for multiple covariates in fractional polynomial models. There was significant sex heterogeneity with regard to the association between BOG and obesity, that is, lower odds of obesity (OR 0.24; 95% CI 0.06 to 0.94) were found in female children but not in male children.ConclusionThe BOG was positively associated with healthier growth of children including decreased risks of both undernutrition and overnutrition. More attention should be given to the improvement of health surveillance and services before and after sporting events so that the active role of such mega-events in the lasting well-being of the public can be determined in more detail.
Rest-activity circadian rhythm and impaired glucose tolerance in adults: an analysis of NHANES 2011–2014
Authors: Xu Yanyan , Su Shaoyong , McCall William V , Isales Carlos , Snieder Harold , Wang Xiaoling 
Published: March 2022

IntroductionCircadian rhythm disturbance occurs in type 2 diabetes, yet it is unknown whether it also exists in the prediagnostic phase of the disease. Thus, we examined the association of rest-activity circadian rhythm with 2-hour glucose levels and the risk of impaired glucose tolerance (IGT) in a nationally representative sample of adults without diabetes using a cross-sectional design.Research design and methodsWe analyzed data from 2760 adults without diabetes (age ≥20) with at least 4 days of validated accelerometer recordings and a valid oral glucose tolerance test from the National Health and Nutrition Examination Survey 2011–2014. Non-parametric rest-activity circadian rhythm parameters were derived from the accelerometer recordings.ResultsIn the models adjusting for multiple covariates, a one-quantile increase in relative amplitude (ie, increased circadian rhythmicity) was associated with 2.66 mg/dL decrease in 2-hour glucose level (95% CI −3.94 to −1.38, p<0.001) and a decreased odds of IGT (OR 0.75, 95% CI 0.63 to 0.89, p=0.002). A one-quantile increase in intradaily variability (ie, increased rhythm fragmentation) was associated with 3.01 mg/dL increase in 2-hour glucose level (95% CI 1.52 to 4.49, p=0.001) and an increased odds of IGT (OR 1.37, 95% CI 1.19 to 1.58, p<0.001).ConclusionsCircadian disruption is significantly associated with impaired glucose homeostasis in a general population of adults without diabetes. The association of circadian rhythm abnormalities with indicators of the pre-diabetic state suggests that circadian dysfunction may contribute to early disease pathogenesis.
Evaluating a community respiratory physiotherapy service for children with neurodisability
Authors: Smith Samantha , Flanigan Moira , Haynes Sarah , Michael Anastasia , Wolff Toni 
Published: March 2022

BackgroundChildren with neurodisability are at an increased risk of respiratory problems and complications, which often result in prolonged, frequent hospital admissions and are the biggest cause of mortality in this client group. The Children’s Community Respiratory Physiotherapy Service (CCRPS) was established in 2010 to support children with severe neurodisabilities at home during acute chest infections and to prevent emergency department attendances and hospital admissions. This service evaluation looked at patient/parent satisfaction and prevented admissions to ensure clinical and cost-effectiveness, despite the rising demand for the service.MethodsOver a 3-month period, patients and parents/carers on the CCRPS caseload were given a Picker feedback survey following 100 emergency visits from the team. The number of prevented hospital admissions for respiratory tract infection over 12 months (April 2019–March 2020) was identified from existing CCRPS data and hospital admissions costs saved were estimated.ResultsThe Picker survey responses were extremely positive with all respondents reporting that they felt well looked after and that the main reason for the emergency visit was dealt with well. Based on key indicators, the CCRPS prevented 182 hospital admissions for respiratory tract infection in 2019/2020, equating to 1638 bed days and estimated cost savings ranging between £751 728 and £1 009 986.ConclusionsThe Picker survey response demonstrates the positive impact that the CCRPS has on both quality of life and experience for patients and families. The CCRPS rapid response service prevents hospital admissions for respiratory tract infections in children and young people with severe neurodisability and the cost savings from admissions prevented allows the service to more than pay for itself.
Epithelial RAC1-dependent cytoskeleton dynamics controls cell mechanics, cell shedding and barrier integrity in intestinal inflammation
Authors: Martínez-Sánchez Luz del Carmen , Ngo Phuong Anh , Pradhan Rashmita , Becker Lukas-Sebastian , Boehringer David , Soteriou Despina , Kubankova Marketa , Schweitzer Christine , Koch Tatyana , Thonn Veronika , Erkert Lena , Stolzer Iris , Günther Claudia , Becker Christoph , Weigmann Benno , Klewer Monika , Daniel Christoph , Amann Kerstin , Tenzer Stefan , Atreya Raja , Bergo Martin , Brakebusch Cord , Watson Alastair J M , Guck Jochen , Fabry Ben , Atreya Imke , Neurath Markus F , López-Posadas Rocío 
Published: March 2022

ObjectiveIncreased apoptotic shedding has been linked to intestinal barrier dysfunction and development of inflammatory bowel diseases (IBD). In contrast, physiological cell shedding allows the renewal of the epithelial monolayer without compromising the barrier function. Here, we investigated the role of live cell extrusion in epithelial barrier alterations in IBD.DesignTaking advantage of conditional GGTase and RAC1 knockout mice in intestinal epithelial cells (Pggt1biΔIECandRac1iΔIECmice), intravital microscopy, immunostaining, mechanobiology, organoid techniques and RNA sequencing, we analysed cell shedding alterations within the intestinal epithelium. Moreover, we examined human gut tissue and intestinal organoids from patients with IBD for cell shedding alterations and RAC1 function.ResultsEpithelialPggt1bdeletion led to cytoskeleton rearrangement and tight junction redistribution, causing cell overcrowding due to arresting of cell shedding that finally resulted in epithelial leakage and spontaneous mucosal inflammation in the small and to a lesser extent in the large intestine. Both in vivo and in vitro studies (knockout mice, organoids) identified RAC1 as a GGTase target critically involved in prenylation-dependent cytoskeleton dynamics, cell mechanics and epithelial cell shedding. Moreover, inflamed areas of gut tissue from patients with IBD exhibited funnel-like structures, signs of arrested cell shedding and impaired RAC1 function. RAC1 inhibition in human intestinal organoids caused actin alterations compatible with arresting of cell shedding.ConclusionImpaired epithelial RAC1 function causes cell overcrowding and epithelial leakage thus inducing chronic intestinal inflammation. Epithelial RAC1 emerges as key regulator of cytoskeletal dynamics, cell mechanics and intestinal cell shedding. Modulation of RAC1 might be exploited for restoration of epithelial integrity in the gut of patients with IBD.