Central adiposity and hemodynamic functioning at rest and during stress in adolescents

OBJECTIVE: To examine the impact of central adiposity upon hemodynamic functioning at rest and during stress in adolescents. DESIGN: Cross-sectional, correlational study. SUBJECTS: 46 White and 49 Black normotensive adolescents with family histories of essential hypertension. MEASUREMENTS: Systolic and diastolic blood pressure (SBP, DBP), cardiac output and total peripheral resistance responses were assessed at rest, during postural change, video game challenge and forehead cold stimulation. Specific lower and higher waist-to-hip ratio (WHR) tertiles were created for each gender and then integrated for analyses. This resulted in a lower WHR tertile of 11 Whites and 21 Blacks and an upper WHR tertile of 15 Whites and 17 Blacks. RESULTS: No differences in age, gender or ethnicity proportions were found between tertile groups (all P > 0.21). The upper WHR group showed greater body weight, waist and hip circumferences, body mass index (BMI), triceps skinfold and body surface area (all P < 0.001). Controlling for peripheral (that is, triceps skinfold) and overall (that is, BMI) adiposity, the upper WHR group exhibited greater SBP (that is, peak response minus mean pre-stressor level) to all three stressors and greater DBP reactivity to postural change and cold pressor (all P < 0.05). CONCLUSION: Central adiposity appears to adversely influence hemodynamic functioning during adolescence. Underlying mechanisms responsible for these associations require exploration.     

Distributed interactive simulation in the evolution of DoD warfaremodeling and simulation

Distributed interactive simulation (DIS) is a revolutionary development that is changing permanently many features of Defense Department work. The field of warfare modeling and simulation (M&S) is quite large, however, and this paper reviews its evolution and how DIS fits within it. A few things are clear. First, DIS is exceedingly valuable for training. Second, DIS could be a powerful means for improving the quality of planning and analysis if used wisely for occasional well designed experiments. These could 1) provide insights about real-world processes involving human performance and behavior (including decision making), 2) help inform and calibrate models, and 3) help test plans in a quasioperational environment. Third, distributed war gaming, which depends on DIS technology, is already lowering boundaries among developers, planners, and warfighters. This can shorten development processes and improve the results through virtual prototyping; it can also improve operational readiness. To achieve these potential benefits, however, will require a holistic approach, conceptual breakthroughs, and profoundly difficult model development efforts. The challenges include developing integrated hierarchies of models, developing adaptive decision models and other models of human behavior, developing and using new forms of uncertainty-sensitive analysis, and learning how to use DIS experiments effectively     

Melting of a DNA hairpin without hyperchromism

UV absorbance spectroscopy is the most common method for detecting nucleic acid structural transitions and obtaining thermodynamic parameters. UV-detected melting has been used to determine stabilities of nucleic acid hairpins, duplexes, triplexes, and higher order structures and to determine thermodynamic effects of unusual or modified bases and mismatched base-pairs. We report that in some cases UV absorbance spectroscopy is an inadequate analytical technique for these purposes. Some critical transitions are invisible to UV absorbance spectroscopy. For example, the conversion of dodecamer d(CGCAAATTCGCG) from hairpin to random coil is not accompanied by hyperchromism. Circular dichroism (CD) spectroscopy (263 nm) clearly detects two transitions for this dodecamer, each giving a pronounced change in ellipiticity. The concentration dependence of the low-temperature transition and the concentration independence of the high-temperature transition indicate that the predominant state converts from duplex to hairpin to random coil as the temperature increases. These assignments are confirmed by comparison to oligonucleotides of similar sequence that undergo a hairpin to coil transition only. In contrast to CD spectroscopy, UV absorbance spectroscopy shows only a single transition. The transition detected by UV absorbance spectroscopy corresponds to the low-temperature transition detected by CD. UV absorbance spectroscopy does not detect the second transition at any wavelength (from 218 to 310 nm) (by changes) in either absorbance or its derivative with temperature.     

Progressive familial leukodystrophy of late onset

We report a family in which three siblings developed dementia between the ages of 40 and 70 years. Two of the siblings developed symptoms of depression, abnormal behavior, and an inability to function, progressing to severe dementia. The third sibling had a severe dementia, the clinical details of which are not available. In the two deceased siblings neuropathologic examinations demonstrated severe demyelination, axon loss, and gliosis in cerebral white matter. Cerebellar and brainstem white matter were unaffected. Cerebral gray matter was negligibly affected. The disorder, histopathologically classified as a pigmented orthochromatic leukodystrophy, is extremely rare. Its etiology is unknown, but the pathology and familial occurrence imply that it represents a genetic defect in a function localized in the cerebral white matter.     

Networking,Storytelling and Knowledge Production in First-Year Writing

As writing teachers, we seek to validate the knowledge that students bring to the classroom while introducing and cultivating new methods, strategies, techniques and technologies that may serve them now and in the future. In this article we describe an approach we take that integrates curricular and extracurricular co-apprenticeship strategies using public writing models in conjunction with social networking tools. With publication as a final goal, we urge students to move from expressing personal problems to addressing social issues, using a private, non-commercial learning network NoDiff <http://NoDiff.com> as a safe zone for skills development, knowledge production and social inquiry. In taking this approach, we resist dichotomies that place professional skills training in strict opposition to critical pedagogy. We argue that many of the so-called “extracurricular” composing activities that most of today's students engage in lay the groundwork for both professional and civic participation. Acknowledging that we as composition teachers are also beginners in the world of 21^st century communication, we emphasize both (1) the continual transference of skills and knowledge among teachers and learners; and (2) the importance of providing what is often lacking in skills-based ‘new literacy’ training, namely a critical pedagogical approach to learning as social engagement and critical intervention.     

The effective thermal conductivity of a composite material with spherical inclusions

A new method is presented for calculating the effective thermal conductivity of a composite material containing spherical inclusions. The surface of a large body is assumed kept at a uniform temperature. This body is in contact with a composite material of infinite extent having a lower temperature far from the heated body. Green's theorem is then used to calculate the rate of heat transfer from the heated body to the composite material, yielding $$k_e /k = 1 + \frac{{3(\alpha - 1)}}{{[\alpha + 2 - (\alpha - 1)\phi ]}}\{ \phi + f(\alpha )\phi ^2 + 0(\phi ^3 )\} $$ where k _e is the effective thermal conductivity, k is the thermal conductivity of the continuous phase, α is the ratio of the thermal conductivity of the spherical inclusions to k, and φ is the volume fraction occupied by the dispersed phase. The function f(α) is presented in this work. Although a similar result has been found previously by renormalization techniques, the method presented in this paper has merit in that a decaying temperature field is used. As a result, only convergent integrals are encountered, and a renormalization factor is not needed. This method is more straightforward than its predecessors and sheds additional light on the basic properties of two-phase materials.     

Use of hydration inhibitors to improve bond durability of aluminium adhesive joints

The adsorption of selected organic hydration inhibitors onto Forest Products Laboratory (FPL)-etched aluminium surfaces and the subsequent hydration of the treated surfaces have been studied using X-ray photoelectron spectroscopy (XPS) and surface behaviour diagrams (SBDs) supplemented by Fourier Transform Infra-red Spectroscopy (FTIR). Wedge tests were used to evaluate performance of these inhibitors in improving bond durability and the locus of failure was identified by XPS and high resolution scanning electron microscopy (X-SEM). The results indicate that nitrilotris methylene phosphonic acid (NTMP) and related compounds adsorb to the alumina surface via the POH bonds of the phosphonic acid groups, resulting in a displacement of water normally adsorbed onto the surface. A model of adsorption was developed which suggests that after treatment with very low concentrations of inhibitor (1 ppm), only one leg of the NTMP molecule adsorbs onto the surface although at higher concentrations (100 ppm) all three legs adsorb. Hydration is a three-step process: (i) reversible physisorption of water; (ii) slow dissolution of the inhibitor followed by rapid hydration of the freshly exposed Al₂O₃ to boehmite (AlOOH); and (iii) further hydration of the AlOOH to bayerite [Al(OH)₃]. Analysis of the adsorption, hydration, and wedge test results using different inhibitors suggests the following five inhibitor characteristics that promote good bond performance: (i) displacement of water and occupation of all active sites on the Al₂O₃ surface; (ii) formation of strong inhibitor surface bonds; (iii) insolubility of the resulting inhibitor-aluminium complex in aqueous solutions; (iv) compatibility with the adhesive or primer; (v) coupling of the inhibitor to the adhesive.     

Soluble Epoxide Hydrolase Blockade after Stroke Onset Protects Normal but Not Diabetic Mice

Soluble epoxide hydrolase (sEH) is abundant in the brain, is upregulated in type 2 diabetes mellitus (DM2), and is possible mediator of ischemic injury via the breakdown of neuroprotective epoxyeicosatrienoic acids (EETs). Prophylactic, pre-ischemic sEH blockade with 4-[[trans-4-[[(tricyclo[3.3.1.13,7]dec-1-ylamino)carbonyl]amino]cyclohexyl]oxy]-benzoic acid (tAUCB) reduces stroke-induced infarct in normal and diabetic mice, with larger neuroprotection in DM2. The present study tested whether benefit occurs in normal and DM2 mice if tAUCB is administered after stroke onset. We performed 60 min middle cerebral artery occlusion in young adult male C57BL mice divided into four groups: normal or DM2, with t-AUCB 2 mg/kg or vehicle 30 min before reperfusion. Endpoints were (1) cerebral blood flow (CBF) by laser Doppler, and (2) brain infarct at 24 h. In nondiabetic mice, t-AUCB reduced infarct size by 30% compared to vehicle-treated mice in the cortex (31.4 ± 4 vs. 43.8 ± 3 (SEM)%, respectively) and 26% in the whole hemisphere (26.3 ± 3 vs. 35.2 ± 2%, both p < 0.05). In contrast, in DM2 mice, tAUCB failed to ameliorate either cortical or hemispheric injury. No differences were seen in CBF. We conclude that tAUCB administered after ischemic stroke onset exerts brain protection in nondiabetic but not DM2 mice, that the neuroprotection appears independent of changes in gross CBF, and that DM2-induced hyperglycemia abolishes t-AUCB-mediated neuroprotection after stroke onset.     

Segregation Neutralised Steels: Microstructural Banding Elimination from Dual-Phase Steel Through Alloy Design Accounting for Inherent Segregation

Metallurgical and Materials Transactions A - Banding in commercial dual-phase steels, such as banded ferrite and pearlite or ferrite and martensite microstructures, is inherited from segregation...     

Removal of trace amounts of strontium from aqueous solutions by ion flotation. II Continuous scale operation

A flotation circuit operating on a continuous basis has been designed and constructed for removal of Sr ions from simple aqueous solutions. Under steady-state conditions, a continuous extraction rate of 97.3% has so far been achieved. The effects of changing the gas rate and flow rates of both the Sr and collector solutions were also examined. Finally a discussion is included where the results of these experiments are compared with those from similar continuous-scale experiments where Sr ions are removed by the technique of foam separation.