Direct numerical simulation of gas transfer across the air-water interface driven by buoyant convection

A series of direct numerical simulations of mass transfer across the air-water interface driven by buoyancy-induced convection has been carried out to elucidate the physical mechanisms that play a role in the transfer of heat and atmospheric gases. The buoyant instability is caused by the presence of a thin layer of cold water situated on top of a body of warm water. In time, heat and atmospheric gases diff use into the uppermost part of the thermal boundary layer and are subsequently transported down into the bulk by falling sheets and plumes of cold water. Using a specifically-designed numerical code for the discretization of scalar convection and diffusion, it was possible to accurately resolve this buoyant instability induced transport of atmospheric gases into the bulk at a realistic Prandtl number (Pr = 6) and Schmidt numbers ranging from Sc = 20 to Sc = 500. The simulations presented here provided a detailed insight into instantaneous gas transfer processes. The falling plumes with highly gas-saturated fluid in their core were found to penetrate deep inside the bulk. With an initial temperature difference between the water surface and the bulk of slightly above 2 K peaks in the instantaneous heat flux in excess of 1600 W/m² were observed, proving the potential effectiveness of buoyant convective heat and gas transfer. Furthermore, the validity of the scaling law for the ratio of gas and heat transfer velocities K_L / H_L ∼ (Pr/Sc)^0:5 for the entire range of Schmidt numbers considered was confirmed. A good time-accurate approximation of K_L was found using surface information such as velocity fluctuations and convection cell size or surface divergence. A reasonable time-accuracy for the K_L estimation was obtained using the horizontal integral length scale and the root-mean-square of the horizontal velocity fluctuations in the upper part of the bulk.The German Research Foundation (DFG grant UH242/6-1). Additional funding by the Helmholtz Water Network

The Effects of Helicopter Parenting on Academic Motivation

There is a growing concern that overinvolved, helicopter parenting may have negative consequences for college students’ well-being and academic achievement. The goal of this study was to examine the effects of helicopter parenting on constructs related to academic achievement and success such as motivation for learning, perfectionism, and entitlement. Survey data are presented from 192 college students and their mothers (N = 121). Children’s report of maternal helicopter parenting was related to extrinsic motivation to learn, perfectionistic discrepancy, and avoidance goals for learning, which have been associated with lower academic performance in prior research. Mother’s report of helicopter parenting was related to children’s sense of entitlement. This study suggests that helicopter parenting is related to maladaptive academic motivations that may have negative implications for academic achievement

Insight into the Parenthood Paradox: Mental Health Outcomes of Intensive Mothering

Though people often report wanting to have children because they think it will make them happier, much research suggests that parenting is associated with decreased well-being. Other studies have found that parenting is related to increased life satisfaction. The goal of this study was to provide insight into this paradox by investigating the relationship between a specific way of parenting, intensive parenting, and maternal mental health. An online survey was completed by 181 mothers with children ages 5 and under. Intensive mothering beliefs correlated with several negative mental health outcomes. Controlling for perceived family social support, the belief that women are the essential parent was related to lower life satisfaction and believing that parenting is challenging was related to greater depression and stress. The results of this study suggest that aspects of intensive mothering beliefs are detrimental to women’s mental health. It may not be parenting per se, but specific and particularly intensive ways of parenting, that relate to negative mental health outcomes

Maternal Guilt and Shame: The Role of Self-discrepancy and Fear of Negative Evaluation

Guilt and shame are emotions commonly associated with motherhood. Self-discrepancy theory proposes that guilt and shame result from perceived discrepancies between one’s actual and ideal selves. Fear of negative evaluation by others may enhance the effects of self-discrepancy especially for shame, which involves fear of others’ reproach. The purpose of this study was to examine the relationships between self discrepancy, guilt, shame, and fear of negative evaluation in a cross-sectional, self report study of mothers. Mothers of children five and under (N = 181) completed an on-line survey measuring guilt, shame, fear of negative evaluation, and maternal self-discrepancies. Guilt and shame were related to maternal self-discrepancy and fear of negative evaluation. In addition, fear of negative evaluation moderated the relationship between maternal self-discrepancy and shame such that mothers who greatly feared negative evaluation had a very strong relationship between these variables. Maternal self-discrepancy and shame were not related among mothers who had low fear of negative evaluation. The results are discussed in terms of the detrimental effects of internalizing idealized standards of perfect motherhood

Quantum computers can search rapidly by using almost any transformation

A quantum computer has a clear advantage over a classical computer for exhaustive search. The quantum mechanical algorithm for exhaustive search was originally derived by using subtle properties of a particular quantum mechanical operation called the Walsh-Hadamard (W-H) transform. This paper shows that this algorithm can be implemented by replacing the W-H transform by almost any quantum mechanical operation. This leads to several new applications where it improves the number of steps by a square-root. It also broadens the scope for implementation since it demonstrates quantum mechanical algorithms that can readily adapt to available technology.Comment: This paper is an adapted version of quant-ph/9711043. It has been modified to make it more readable for physicists. 9 pages, postscrip

Intensive Parenting: Does it Have the Desired Impact on Child Outcomes?

Although parental involvement is generally thought to be beneficial for children, it is unclear whether the intensive level of parenting that has become commonplace results in improved child outcomes. Intensive parenting may involve the desire to anticipate and solve children’s problems as well as to enroll them in numerous, structured activities that might enhance their physical, cognitive, and social abilities. We surveyed 241 parents to assess intensive parenting beliefs, anticipatory problem solving (APS), enrollment in structured activities, and developmental outcomes of their children ages 2–5. Using structural equation modeling, we found that intensive parenting beliefs predicted more APS, which predicted greater enrollment in creative and physical activities. However, enrollment in structured activities did not predict children’s developmental outcomes. Although parents may believe that expensive and time-consuming activities are the keys to ensuring their children’s health, happiness, and success, this study does not support this assumption

Effect of Fluoride and Cobalt on Forming Enamel: Scanning Electron Microscope and X-Ray Microanalysis Study

The forming surfaces of enamel of rat incisors were examined by scanning electron microscope one hour after injection of either 5 mg/100 g body weight of sodium fluoride or 12 mg/100 g body weight of cobalt chloride. The cell debris from the surfaces of the separated incisors was either gently wiped off with soft facial tissues or chemically removed by treating with NaOH, NaOCl or trypsin. Best results to remove cell debris were obtained from 0.25% trypsin treatment. SEM studies revealed that the surface of the normal secretory enamel was characteristic in appearance with well-developed smooth prism outlines. In fluoride specimens the prism outlines were feathery in appearance, laced with protruding spine-shaped clusters of mineral crystals. In the case of cobalt treatment, prism outlines were less uniform and in some areas they were incomplete. The calcium concentration of surface enamel was significantly lower in the cobalt-treated specimens than those from control and fluoride-treated animals. The Ca:Mg ratio was also lower in cobalt-treated specimens as compared to control and fluoride-treated ones

Development and Validation of a Quantitative Measure of Intensive Parenting Attitudes

Intensive mothering (IM) attitudes have been considered the dominant discourse of motherhood, but have only been assessed qualitatively The goal of this study was to develop a quantitative scale to assess these ideologies, their construct validity, and their relationship to relevant constructs (i.e., work status and division of household labor). An on-line questionnaire was given to 595 mothers asking 56 questions assessing different aspects of IM attitudes as well as several validation measures. An Exploratory Factor Analysis on 315 randomly selected mothers yielded a 5 factor solution. A Confirmatory Factor Analysis on the remaining 280 mothers demonstrated good fit. The five factors expressed the ideas that 1) women are inherently better at parenting than men (Essentialism), 2) parenting should be fulfilling (Fulfillment), 3) children should be cognitively stimulated by parents (Stimulation), 4) mothering is difficult (Challenging), and 5) parents should prioritize the needs of the child (Child-Centered). Scales had adequate reliability and construct validity compared to the Parental Investment in Child scale, the Parenting Sense of Competence Scale, and Beliefs about Maternal Employment. The Essentialism, Fulfillment, and Challenging scales were positively related to having more responsibility for childcare and household chores. Stay-at-home mothers had higher scores on Essentialism and lower scores on Stimulation than both part-time and full-time working mothers supporting the notion that both working and non-working mothers have intensive parenting ideologies that are manifested in different ways

Virtual reality suturing task as an objective test for robotic experience assessment

BackgroundWe performed a pilot study using a single virtual-simulation suturing module as an objective measurement to determine functional use of the robotic system. This study will assist in designing a study for an objective, adjunctive test for use by a surgical proctor.MethodsAfter IRB approval, subjects were recruited at a robotic renal surgery course to perform two attempts of the "Tubes" module without warm-up using the Da Vinci® Surgical Skills Simulator™. The overall MScore (%) from the simulator was compared among various skill levels to provide construct validity. Correlation with MScore and number of robotic cases was performed and pre-determined skill groups were tested. Nine metrics that make up the overall score were also tested via paired t test and subsequent logistic regression to determine which skills differed among experienced and novice robotic surgeons.ResultsWe enrolled 38 subjects with experience ranging from 0- < 200 robotic cases. Median time to complete both tasks was less than 10 min. The MScore on the first attempt was correlated to the number of previous robotic cases (R(2) = 0.465; p = 0.003). MScore was different between novice and more experienced robotic surgeons on the first (44.7 vs. 63.9; p = 0.005) and second attempt (56.0 vs. 69.9; p = 0.037).ConclusionA single virtual simulator exercise can provide objective information in determining proficient use of the robotic surgical system