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Daniel Floryan, Tyler Van Buren, Alexander J Smits
Many swimming and flying animals are observed to cruise in a narrow range of Strouhal numbers, where the Strouhal number [Formula: see text] is a dimensionless parameter that relates stroke frequency f, amplitude A, and forward speed U. Dolphins, sharks, bony fish, birds, bats, and insects typically cruise in the range [Formula: see text], which coincides with the Strouhal number range for maximum efficiency as found by experiments on heaving and pitching airfoils. It has therefore been postulated that natural selection has tuned animals to use this range of Strouhal numbers because it confers high efficiency, but the reason why this is so is still unclear...
June 18, 2018: Proceedings of the National Academy of Sciences of the United States of America
Lihua Liang, Jia Yuan, Songtao Zhang, Peng Zhao
This work presents optimal linear quadratic regulator (LQR) based on genetic algorithm (GA) to solve the two degrees of freedom (2 DoF) motion control problem in head seas for wave piercing catamarans (WPC). The proposed LQR based GA control strategy is to select optimal weighting matrices (Q and R). The seakeeping performance of WPC based on proposed algorithm is challenged because of multi-input multi-output (MIMO) system of uncertain coefficient problems. Besides the kinematical constraint problems of WPC, the external conditions must be considered, like the sea disturbance and the actuators (a T-foil and two flaps) control...
2018: PloS One
Chenglei Wang, Hui Tang
In this study, we explore the use of synthetic jet (SJ) in manipulating the vortices around a rigid heaving airfoil, so as to enhance its aerodynamic performance. The airfoil heaves at two fixed pitching angles, with the Strouhal number, reduced frequency and Reynolds number chosen as St  =  0.3, k  =  0.25 and Re  =  100, respectively, all falling in the ranges for natural flyers. As such, the vortex force plays a dominant role in determining the airfoil's aerodynamic performance. A pair of in-phase SJs is implemented on the airfoil's upper and lower surfaces, operating with the same strength but in opposite directions...
May 25, 2018: Bioinspiration & Biomimetics
T H Loong, H M Liu, S S Fong
AIM: Transanal total mesorectal excision (taTME) is a novel approach for resection of the rectum. Use of a standard insufflator to create pneumorectum, however, results in bellowing-large heaving motions from insufflation of air that can frustrate surgery. We report the successful application of our technique, stable pneumorectum using an inline glove (SPRING), for the performance of transanal rectal excision in a series of 17 patients using a standard laparoscopic insufflator. METHOD: A retrospective review of 17 patients using the SPRING technique was performed between October 2015 and October 2016...
May 2018: Colorectal Disease: the Official Journal of the Association of Coloproctology of Great Britain and Ireland
Shaziela Ishak, Andrea Bubka, Frederick Bonato
Sensory conflict theories of motion sickness (MS) assert that symptoms may result when incoming sensory inputs (e.g., visual and vestibular) contradict each other. Logic suggests that attenuating input from one sense may reduce conflict and hence lessen MS symptoms. In the current study, it was hypothesized that attenuating visual input by blocking light entering the eye would reduce MS symptoms in a motion provocative environment. Participants sat inside an aircraft cockpit mounted onto a motion platform that simultaneously pitched, rolled, and heaved in two conditions...
May 2018: Perception
Haleema Shakur, Danielle Beaumont, Sue Pavord, Angele Gayet-Ageron, Katharine Ker, Hatem A Mousa
BACKGROUND: Postpartum haemorrhage (PPH) - heaving bleeding within the first 24 hours after giving birth - is one of the main causes of death of women after childbirth. Antifibrinolytics, primarily tranexamic acid (TXA), have been shown to reduce bleeding in surgery and safely reduces mortality in trauma patients with bleeding without increasing the risk of adverse events.An earlier Cochrane review on treatments for primary PPH covered all the various available treatments - that review has now been split by types of treatment...
February 20, 2018: Cochrane Database of Systematic Reviews
Liping Sun, Jian Deng, Xueming Shao
This paper investigates the three-dimensional instabilities of the flow past a periodically heaving airfoil. By comparison with a pitching foil [Deng et al., Phys. Rev. E 92, 063013 (2015)PLEEE81539-375510.1103/PhysRevE.92.063013], here we present distinctive characteristics for the heaving foil, particulary regarding its Floquet modes. By increasing the frequency (Sr), or equivalently decreasing the amplitude (A_{D}) along the marginal stability curve in the (Sr,A_{D}) phase space, the critical Floquet mode emerges sequentially as A, quasiperiodic (QP), and B...
January 2018: Physical Review. E
Rui Peng, Xiangrui Meng, Guangming Zhao, Yingming Li, Jianming Zhu
We study the structural instability mechanism and effect of a multi-echelon support in very-deep roadways. We conduct a scale model test for analysing the structural failure mechanism and the effect of multi-echelon support of roadways under high horizontal stress. Mechanical bearing structures are classified according to their secondary stress distribution and the strength degradation of the surrounding rock after roadway excavation. A new method is proposed by partitioning the mechanical bearing structure of the surrounding rock into weak, key and main coupling bearing stratums...
2018: PloS One
Xiaolin Wang, Silas Alben
Over the past few decades, oscillating flexible foils have been used to study the physics of organismal propulsion in different fluid environments. Here, we extend this work to a study of flexible foils in a frictional environment. When the foil is oscillated by heaving at one end but is not free to locomote, the dynamics change from periodic to non-periodic and chaotic as the heaving amplitude increases or the bending rigidity decreases. For friction coefficients lying in a certain range, the transition passes through a sequence of N -periodic and asymmetric states before reaching chaotic dynamics...
January 2018: Proceedings. Mathematical, Physical, and Engineering Sciences
Peter Zhang, Berk Tulu, Morgan Sears, Jack Trackemas
Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground fall fatalities in underground coal mines in the United States. The risk of ground falls during pillar recovery increases in multiple-seam mining conditions. The hazards associated with pillar recovery in multiple-seam mining include roof cutters, roof falls, rib rolls, coal outbursts, and floor heave. When pillar recovery is planned in multiple seams, it is critical to properly design the mining sequence and panel layout to minimize potential seam interaction...
January 2018: International Journal of Mining Science and Technology
Sarab Sodhi
No abstract text is available yet for this article.
April 2018: Academic Emergency Medicine: Official Journal of the Society for Academic Emergency Medicine
Satyajit Pramanik, John S Wettlaufer
We examine the effects of confinement on the dynamics of premelted films driven by thermomolecular pressure gradients. Our approach is to modify a well-studied setting in which the thermomolecular pressure gradient is driven by a temperature gradient parallel to an interfacially premelted elastic wall. The modification treats the increase in viscosity associated with the thinning of films, studied in a wide variety of materials, using a power law and we examine the consequent evolution of the confining elastic wall...
November 2017: Physical Review. E
Elizabeth Crouch, Elizabeth Radcliff, Melissa Strompolis, Abygail Wilson
BACKGROUND: Adverse childhood experiences (ACEs) have been associated with negative adult health outcomes, including alcohol misuse. The impact of ACEs on alcohol use may vary by gender, with ACEs impacting women more than men in coping with adulthood stressors. OBJECTIVES: The objective of this study is to examine the gender-specific relationships between ACEs and self-reported binge drinking and heavy drinking in adulthood among South Carolina residents. METHODS: This study analyzed a sample of 8492 respondents who completed the 2014 or 2015 South Carolina Behavioral Risk Factor Surveillance System (BRFSS) survey...
November 29, 2017: Substance Use & Misuse
Weiwei Zhang, Xiao-Hai Yan
The Subpolar North Atlantic (SPNA) is one of the most important areas to global climate because its ocean heat content (OHC) is highly correlated with the Atlantic Meridional Overturning Circulation (AMOC), and its circulation strength affects the salt transport by the AMOC, which in turn feeds and sustains the strength of the AMOC. Moreover, the recent global surface warming "hiatus" may be attributed to the SPNA as one of the major planetary heat sinks. Although almost synchronized before 1996, the OHC has greater spatial disparities afterwards, which cannot be explained as driven by the North Atlantic Oscillation (NAO)...
October 23, 2017: Scientific Reports
Wei Chen, Qi Jia, Yifan Song, Haihui Fu, Gang Wei, Ting Ni
Alternative polyadenylation (APA), a phenomenon that RNA molecules with different 3' ends originate from distinct polyadenylation sites of a single gene, is emerging as a mechanism widely used to regulate gene expression. In the present review, we first summarized various methods prevalently adopted in APA study, mainly focused on the next-generation sequencing (NGS)-based techniques specially designed for APA identification, the related bioinformatics methods, and the strategies for APA study in single cells...
October 2017: Genomics, Proteomics & Bioinformatics
Xiang Kong, Yan Kong, Jin Yan, Jin-Ju Hu, Fang-Fang Wang, Lei Zhang
Effective diagnosis and clinical management of placenta accreta (PA) in China are not clear. The purpose of the study was to analyze the risk factors and diagnosis of PA, maternal and neonatal outcomes in patients with PA. It was a retrospective study of cases with PA, confirmed by histologically and/or clinically suspected during 3 years in 2 tertiary referral hospitals. The incidence rate of patients with PA, who had history of artificial abortion, cesarean section (CS), and placenta previa (PP) was 94%, 70%, and 72%, respectively...
September 2017: Medicine (Baltimore)
Huria Ibrahim, Hiba Farah, Amal Zein Eddin, Samih Isber, Rabih Sultan
Metal electrodeposition systems display tree-like structures with extensive ramification and a fractal character. Electrolysis is not a necessary route for the growth of such dendritic metal deposits. We can grow beautiful ramification patterns via a simple redox reaction. We present here a study of silver (Ag) deposits from the reduction of Ag(+) in (AgNO3) solution by metallic copper. The experiments are carried out in discotic geometry, in a Petri dish hosting a thin AgNO3 solution film. A variety of deposited structures and patterns is obtained at different Ag(+) concentrations, yet with essentially the same fractal dimension averaged at 1...
August 2017: Chaos
William Humberto Cuellar Sanchez, Tássio Melo Linhares, André Benine Neto, Eugênio Libório Feitosa Fortaleza
Heave compensator is a system that mitigates transmission of heave movement from vessels to the equipment in the vessel. In drilling industry, a heave compensator enables drilling in offshore environments. Heave compensator attenuates movement transmitted from the vessel to the drill string and drill bit ensuring security and efficiency of the offshore drilling process. Common types of heave compensators are passive, active and semi-active compensators. This article presents 4 main points. First, a bulk modulus analysis obtains a simple condition to determine if the bulk modulus can be neglected in the design of hydropneumatic passive heave compensator...
2017: PloS One
Yiqi Wang, Yiqiu Tan, Meng Guo, Xinglong Wang
Properties of cement-stabilized gravel modified by emulsified asphalt under freezing and thawing cycle conditions were investigated by adjusting the dosage of cement. Mercury intrusion porosimetry (MIP) and Scanning electron microscopy (SEM) were introduced to analyze the influential mechanism. The results indicate that cement emulsified asphalt stabilized gravel with 5 wt % of cement performed well in both mechanics and frost-resistance. Although the addition of emulsified asphalt would lead to a partial decrease of strength, it can extend the process of strength loss and improve the freezing resistance...
May 6, 2017: Materials
D Schnider, S Rieder, T Leeb, V Gerber, M Neuditschko
Recurrent airway obstruction (RAO), also known as heaves, is an asthma-like respiratory disease. Its development is strongly influenced by environmental risk factors such as sensitization and exposure to moldy hay, straw bedding and stabling indoors. A hereditary component has been documented in previous studies; however, so far no causative genetic variant that influences the risk of developing RAO has been identified. In this study, we revised an existing dataset and selected 384 horses for genotyping on the Affymetrix high-density equine SNP array...
December 2017: Animal Genetics
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