Effect of Roots and Tillage on Soil Erosion on a Weathered Hawaiian Soil With Low Erodibility

Sustainable farming of marginal lands in the tropics is partially constrained by destructive effects of soil erosion. One farming system proposed for controlling erosion on steep lands is alleycropping, in which crops are grown between parallel hedgerows of trees or shrubs. This study was originally designed to evaluate the mechanisms by which alleycropping could reduce erosion on a steep slope. The site was located on Kauai, Hawaii, on a steep slope (40%) of a soil classified as the Halii series, an Anionic Acrudox. A preexisting thick vegetation of ferns and shrubs was cleared by bulldozer and subsequently disked twice and hand-raked. Twelve plots, 3 replications of 4 treatments (bare, monocrop, and 2 variations of an alleycrop) were installed on 16 by 4 m plots surrounded by steel sheet metal. Runoff and sediment was collected and measured from each plot for 1 year. However, soil loss and runoff were not related to treatments, occurring only on 2 plots (Plots #11 and #12) despite several heavy storms. Total runoff and soil loss were 1.1% of rainfall and 0.7 T/ha and 1.9% and 27 T/ha for Plot 11 and 12, respectively. Fine root content, tillage and exposure, and mineralogy of the soil were investigated to explain these results. Disking and raking had created a well aggregated highly porous, and friable soil structure with high infiltration rates. Exposure and drying of the soil apparently allowed its structure to remain very stable and resistant to structural and aggregate disintegration under the force of raindrops. The two plots with runoff were apparently disked to a shallower depth, thus limiting these effects of tillage and exposure on the soil structure. Very high fine root content in Plot 11 bound soil aggregates together and reduced soil loss in this plot despite significant runoff. A sharp increase of halloysite content correlated with an increase of runoff and soil loss, but was believed to have affected chiefly only runoff. This highly weathered tropical soil was resistant to erosion, but the demonstrated high spatial variability in prior vegetation, clearing, tillage, and mineralogy, must be taken into account in designing future research in tropical farming systems

Potential for head injuries in infants from low-height falls: Laboratory investigation

Object. Falls are the most common accident scenario in young children as well as the most common history provided in child abuse cases. Understanding the biomechanics of falls provides clinicians with objective data to aid in their diagnosis of accidental or inflicted trauma. The objective of this study was to determine impact forces and angular accelerations associated with low-height falls in infants. Methods. An instrumented anthropomorphic infant surrogate was created to measure the forces and 3D angular accelerations associated with falls from low heights (0.3–0.9 m) onto a mattress, carpet pad, or concrete. Results. Although height significantly increased peak angular acceleration (αp), change in peak-to-peak angular velocity, time duration associated with the change in velocity, and peak impact force (Fp) for head-first drops onto a carpet pad or concrete, none of these variables were significantly affected by height when dropped onto a mattress. The αp was not significantly different for drops onto a carpet pad and concrete from 0.6 or 0.9 m due to compression of the carpet pad. Surprisingly, sagittal αp was equaled or surpassed by axial αp. Conclusions. These are the first 3D angular acceleration and impact force data available for head impact in infants from low-height falls. A future study involving a computational model of the infant head will use the loads measured in this study to predict the probability of occipital skull fracture on impact from head-first low-height falls. Together, these studies will provide data that will aid clinicians in the evaluation of accidental and inflicted head injuries, and will contribute to the design of safer environments for children. (DOI: 10.3171/PED.2008.2.11.321

Firewall argument for acoustic black holes

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. June 8, 2015.We investigate the rewall paradox proposed by AMPS [1] by rst explaining the Information Paradox together with Hawking's derivation of the thermal radiation emitted from a evaporating black hole [28]. We then ask if one can apply arguments similar to that of Hawking and AMPS in the regime of uid mechanics, which was rst considered by Unruh [59]. We assume that a black hole, with a geometry conformal to the Schwarzschild metric, can be formed in a uid. The sonic hole or \dumb" hole, which is characterized by an acoustic event horizon, is the locus of points at which the background uid is traveling at the local speed of sound. Since sound disturbances are coupled to the background uid and travel at the speed of sound, the acoustic event horizon a ects sound disturbances in a manner analogous to how gravitational black holes a ect light [62]. Like a gravitational black hole, which evaporates by emitting Hawking radiation, we check if an acoustic black hole will emit in a similar kind of radiation in the form of phonons. This is done by constructing a massless scalar eld describing phonon propagation and treating the acoustic black hole just like a gravitational black hole. We apply the arguments put forth by Hawking and AMPS and see if there is any validity to an \acoustic rewall" as this would require certain physical phenomena emerging from sub-atomic scales

Physiological and clinical consequences of relief of right ventricular outflow tract obstruction late after repair of congenital heart defects.

BACKGROUND: Right ventricular outflow tract obstruction (RVOTO) is a common problem after repair of congenital heart disease. Percutaneous pulmonary valve implantation (PPVI) can treat this condition without consequent pulmonary regurgitation or cardiopulmonary bypass. Our aim was to investigate the clinical and physiological response to relieving RVOTO. METHODS AND RESULTS: We studied 18 patients who underwent PPVI for RVOTO (72% male, median age 20 years) from a total of 93 who had this procedure for various indications. All had a right ventricular outflow tract (RVOT) gradient >50 mm Hg on echocardiography without important pulmonary regurgitation (less than mild or regurgitant fraction <10% on magnetic resonance imaging [MRI]). Cardiopulmonary exercise testing, tissue Doppler echocardiography, and MRI were performed before and within 50 days of PPVI. PPVI reduced RVOT gradient (51.4 to 21.7 mm Hg, P<0.001) and right ventricular systolic pressure (72.8 to 47.3 mm Hg, P<0.001) at catheterization. Symptoms and aerobic (25.7 to 28.9 mL.kg(-1).min(-1), P=0.002) and anaerobic (14.4 to 16.2 mL.kg(-1).min(-1), P=0.002) exercise capacity improved. Myocardial systolic velocity improved acutely (tricuspid 4.8 to 5.3 cm/s, P=0.05; mitral 4.7 to 5.5 cm/s, P=0.01), whereas isovolumic acceleration was unchanged. The tricuspid annular velocity was not maintained on intermediate follow-up. Right ventricular end-diastolic volume (99.9 to 89.7 mL/m2, P<0.001) fell, whereas effective stroke volume (43.7 to 48.3 mL/m2, P=0.06) and ejection fraction (48.0% to 56.8%, P=0.01) increased. Left ventricular end-diastolic volume (72.5 to 77.4 mL/m2, P=0.145), stroke volume (45.3 to 50.6 mL/m2, P=0.02), and ejection fraction (62.6% to 65.8%, P=0.03) increased. CONCLUSIONS: PPVI relieves RVOTO, which leads to an early improvement in biventricular performance. Furthermore, it reduces symptoms and improves exercise tolerance. These findings have important implications for the management of this increasingly common condition

Peripartum cardiomyopathy: diagnosis and management

No abstract available

A Parametric Study of a Plug Nozzle, Using the Liquid Propellant Program (LPP) Code

The Liquid Propellant Program (LPP) computer code is a super-set of the industry standard Two Dimensional Kinetics (TDK) computer code. The TDK code uses a two dimensional method of characteristics solution with fully coupled finite rate kinetics for axially symmetric nozzles. The chemical reactions are modeled with a generalized reaction package that include three dimensional body efficiencies and four reaction rate forms. The code performs optional solutions for frozen or equilibrium flow. TDK evaluates discrete shocks, both attached or induced. The Transonic module models variable mixture ratio profiles from the combustion chamber injector. The Mass Addition Boundary Layer module (MABL) calculates the boundary parameters with the same chemistry options, and includes transpiration or tangential slot injection of gas at the wall. The LPP upgrades include: planar nozzle, scarfed nozzles, plug nozzles, and scramjet nozzle configurations. The code evaluates both upper and lower wall flow simulation, and includes the interaction with the external flow. The MABL module evaluates equilibrium radiation heat transfer for both upper and lower walls. In addition, LPP code models combustion effects due to injector inefficiencies with the Spray Combustion Analysis Program (SCAP) module. The LPP package provides extensive post plotting capabilities for flow visualization. The LPP is sufficiently fast and robust to provide performance predictions for extensive parametric studies and sufficiently accurate to provide flow field and performance solutions for detailed studies

i-STEM Summer Institute: An Integrated Approach to Teacher Professional Development in STEM

The importance of STEM education to societal developments provides justification for assuring K–12 teachers are prepared to teach the related content. Inservice teacher professional development is critical to achieving the goal of enhanced student knowledge of STEM. Combining the need for increased capacity to teach STEM and the extant literature on teacher development, we created a four-day residential summer institute for 230 grade 4–9 teachers. The institute was designed to enhance the participants\u27 content knowledge, use of inquiry for instruction, and efficacy for teaching STEM. A combination of content strands, plenary sessions, field trips and planning time were augmented by the provision of the resources necessary to implement the curriculum the participants learned. Pre- and post-test results of the participants\u27 comfort, pedagogical discontentment, inquiry implementation, perceived efficacy, and content knowledge in the context of STEM revealed significant changes (p \u3c 01). In addition, pre- and post-test results indicate the participants’ perceptions and conceptions of STEM achieved substantial gains. Our report provides the details, outcomes, and potential implications for STEM education