bluuebunny/crossref_metadata_2025 huggingface dataset:
Exergetic efficiency optimization of a thermoacoustic cooler
Authors: Chen L , Wu F , Li Q , Guo F , Su A
Published: November 2007

A heat transfer model with a complex exponent between a thermoacoustic cooler and its surrounding heat reservoirs is established in the current paper. Both the real part and the imaginary part of the heat transfer exponent strongly affect the optimal performance of the cooler. The exergetic efficiency and the cooling load decrease with an increase in the imaginary part of the complex exponent when the real part is fixed. The optimal performance zone of the thermoacoustic cooler is obtained by numerical analysis. The results obtained herein may be useful for the selection of operation parameters for a real thermoacoustic cooler.
Application of homogenous transformation matrix to the design and machining of a Geneva mechanism with curved slots
Authors: Hsieh J-F
Published: November 2007

The current paper presents a simple yet comprehensive method for the design and machining of a Geneva indexing mechanism with curved slots. In the proposed approach, a kinematic model of the Geneva mechanism is developed using homogenous coordinate transformation and conjugate surface theory. The pressure angle of Geneva mechanism and the principal curvatures of the curved slots are analysed using an analytical expression derived for the slot profile. The NC data required to machine the driven with curved slots are derived from the CNC link variables by equating the machine tool ability function and the tool location matrix. The proposed design methodology is verified by machining the designed curved slots using a three-axis CNC machine. The results confirm that the approach presented in this study enables the Geneva mechanism design and manufacturing tasks to be successfully integrated, thus making possible a flexible, automatic, cost efficient, and controllable production process.
On the linear stability analysis of finite-hydrodynamic porous journal bearings under coupled stress lubrication
Authors: Guha S. K. , Chattopadhyay A. K.
Published: November 2007

The objective of the present investigation is to study theoretically, using the finite-difference techniques, the dynamic performance characteristics of finite-hydrodynamic porous journal bearings lubricated with coupled stress fluids. In the analysis based on the Stokes micro-continuum theory of the rheological effects of coupled stress fluids, a modified form of Reynolds equation governing the transient-state hydrodynamic film pressures in porous journal bearings with the effect of slip flow of coupled stress fluid as lubricant is obtained. Moreover, the tangential velocity slip at the surface of porous bush has been considered by using Beavers-Joseph criterion. Using the first-order perturbation of the modified Reynolds equation, the stability characteristics in terms of threshold stability parameter and whirl ratios are obtained for various parameters viz. permeability factor, slip coefficient, bearing feeding parameter, and eccentricity ratio. The results show that the coupled stress fluid exhibits better stability in comparison with Newtonian fluid.
Fragility and the dynamic crossover in lubricants
Authors: Bair S , Roland C. M. , Casalini R
Published: November 2007

The property of fragility in glass forming liquids is introduced to elastohydrodynamic lubrication (EHL). Using viscosity measurements for three liquids that have been the subject of traction studies the fragility of liquids is shown to be important to EHL traction and the property that most influences the representative (Eyring) stress. The derivative Stickel analysis is then carried out for lubricants. Using viscosity measurements, the dynamic crossover is detected for the first time in lubricants. The viscosity at the crossover is either constant or varies slowly with temperature and pressure and the crossover pressure varies with temperature in a manner similar to the glass transition pressure. The free-volume model fails to predict the occurrence of the dynamic crossover.
Theoretical and experimental investigation of the effect of oil aeration on the load-carrying capacity of a hydrodynamic journal bearing
Authors: Goodwin M. J. , Dong D , Yu H , Nikolajsen J. L.
Published: November 2007

It is widely assumed that the presence of air bubbles in the lubricating oil of a hydrodynamic bearing gives rise to a reduced load-carrying capacity, because of the high compressibility and low viscosity of the air and its tendency, therefore, to upset the hydrodynamic effect. The aim of the work described in the current paper was to investigate the accuracy of this assumption by theoretical and experimental means, and also to provide quantitative data relating to the concentration of air bubbles and their size that are required for any discernible effect.

The paper has the following three main contributions: (a) a theoretical model based on Reynolds equation, but modified to allow for the effect of aeration on lubricant viscosity and density, is proposed; (b) a novel method of injecting air bubbles into lubricating oil and for measuring their size and concentration was developed; and (c) an experimental hydrodynamic bearing test rig was implemented and run with both aerated and non-aerated lubricating oil, and in each case measurements of the load-carrying capacity for various operating speeds were made.

The results from both theoretical and experiment work show that the presence of air bubbles in the lubricating oil leads to a slight decrease in bearing load-carrying capacity at high operating speeds. For normal operating speeds, however, (i.e. those resulting in eccentricity ratios greater than 0.6) results show that the presence of air bubbles has little effect on bearing load-carrying capacity.
Dynamic Reynolds equation for micropolar fluids and the analysis of plane inclined slider bearings with squeezing effect
Authors: Naduvinamani N. B. , Marali G. B.
Published: November 2007

The general dynamic Reynolds equation of sliding-squeezing surfaces with micro-polar fluids is derived for the assessment of dynamic characteristics of bearings with general film thickness. The detailed analysis is presented for the plane inclined slider bearings by using perturbation method. Two Reynolds-type equations corresponding to steady performance and perturbed characteristics are obtained. The closed form solution of these equations is obtained. The numerical computations of the results show that, the micropolar fluids provide an improved characteristics for both steady-state and the dynamic stiffness and damping characteristics. It is found that the maximum steady-load-carrying capacity is function of coupling parameter and is achieved at smaller values of profile parameter for larger values of the coupling parameter.
Effects of longitudinal roughness on fluid temperature in point elastohydrodynamic lubrication contacts
Authors: Nishikawa H , Ueda K , Kaneta M , Wang J , Yang P
Published: November 2007

The effects of longitudinal surface roughness on the oil film temperature are studied numerically based on Eyring and Newtonian fluid flow models under point contact rolling and sliding elastohydrodynamic lubrication (EHL) conditions. There is a significant difference in oil film temperature distribution between the Eyring or shear thinning fluid and the Newtonian fluid. In shear thinning fluids, the relationship between the oil film temperature distribution and the roughness around the central contact area becomes out-of-phase, i.e. the temperature of oil film is higher at the valley than at the ridge of asperity. Such a phenomenon occurs easily under short wavelength and low amplitude of roughness, and moderate entrainment velocities depending on the slide-roll ratio.
Post-Tensioned Interior Precast Wide Beam—Column Connections Subjected to Lateral Loading
Authors: Moon J. H. , Choi Y. C. , Lim J. H. , Lee L. H. , Kwon K. H. , Kim K. S.
Published: November 2007

The post-tensioned precast concrete system (PPS) developed in this study consists of U-shaped precast wide beams and concrete columns, where the continuity of wide beam-column joint is provided with the cast-in-place concrete on the U-shaped precast wide beam and the post-tensioning to the beam after casting of slab. The PPS structure can overcome the defect of discontinuity in the connections of precast members using cast-in-place concrete on precast members, and complement the low sectional efficiency of wide beam by applying the post-tensioning. In this study, an experimental investigation was performed with three half-scale specimens of interior connection fabricated employing PPS structure. Specifically, this paper presents the response of PPS interior beam-column joint subjected to cyclic lateral loading and evaluates the relevance of the beam-to-column width ratio criteria specified in ACI 318–05. The test results indicate that the PPS specimens can resist properly seismic loads maintaining overall structural integrity.
Simplified Method for Pushover Curves of Asymmetric Structure with Displacement-Dependent Passive Energy Dissipation Devices
Authors: Li Hong-Nan , Li Gang
Published: November 2007

This paper presents a simplified method to calculate pushover curves for an asymmetric structure with displacement-dependent passive energy dissipation devices (DDPEDDs). The deformations of a symmetric structure are analyzed in translation and torsion, respectively. These results are then combined in order to calculate the pushover curve for an asymmetric structure with DDPEDDs. The numerical results obtained by using the simplified analytical method are then compared to those obtained from the analysis of the models using the software SAP2000. The results show that the simplified analytical method can be an effective tool for engineering analysis of an asymmetric structure.
Pultruded FRP Plank as Formwork and Reinforcement for Concrete Members
Authors: Bank Lawrence C. , Oliva Michael G. , Bae Han-Ug , Barker Jeffrey W. , Yoo Seung-Woon
Published: November 2007

A feasibility study in which the use of a commercially produced pultruded fiber reinforced polymer (FRP) plank for both permanent formwork and secondary or primary tensile reinforcement of a concrete structural member is described in this paper. To achieve satisfactory bond at the interface between the smooth surface of the FRP plank and the concrete, two kinds of aggregate, gravel and sand, were epoxy bonded to the planks. Concrete beams using the aggregate-coated FRP planks were fabricated and tested. Satisfactory bond between the FRP plank and the concrete was developed which was evidenced by numerous well-distributed flexural cracks, and ultimate capacities of the aggregate coated FRP plank specimens greater than the steel rebar reinforced control specimen. ACI 440 equations were found to provide good predictions of the flexural strengths but poor predictions of the shear strengths of the FRP plank reinforced beams. ACI 318 equations, however, provided good shear strength predictions.
Finite Element Study of Shear Behavior of Spandrel Ledges and Comparison with PCI Shear Design Provisions
Authors: Hassan Tarek K.
Published: November 2007

Punching shear failure of spandrel ledges has been observed by many researchers and heightened concerns have been raised questioning the safety level of the PCI shear design provisions for beam ledges. This paper presents non-linear finite element analyses conducted to model the behavior of prestressed L-shaped spandrel beams. Special emphasis was given to the behavior of the ledge at the end regions of the spandrel, where punching shear controls the design. The accuracy of the finite element model is demonstrated by comparing the predicted behavior to the results of one major test by another researcher. The influence of different parameters included in the PCI shear design provisions for beam ledges is discussed. The analysis is extended to illustrate the effect of other parameters including the prestressing level, hanger reinforcement and the amount of debonded strands at the end regions of the spandrel beam. Results of the analyses showed that the PCI shear design provisions for spandrel ledges are dangerously unconservative. The provisions do not account for key parameters, which affect the punching shear behavior.
High-Throughput Genotyping of Oncogenic Human Papilloma Viruses with MALDI-TOF Mass Spectrometry
Authors: Söderlund-Strand Anna , Dillner Joakim , Carlson Joyce
Published: November 2007

Background: Human papilloma virus (HPV) is the major cause of cervical cancer. Use of HPV genotyping in cervical screening programs and for monitoring the effectiveness of HPV vaccination programs requires access to economical, high-throughput technology.

Methods: We used the Sequenom MassARRAY platform to develop a high-throughput mass spectrometric (MS) method for detecting 14 specific oncogenic HPV genotypes in multiplex PCR products. We compared results from 532 cervical cell samples to the comparison method, reverse dot blot hybridization (RDBH).

Results: The MS method detected all samples found positive by RDBH. In addition, the MS method identified 5 cases of cervical disease (cervical intraepithelial neoplasia of grade I or higher) that RDBH analysis had missed. Discrepancies in specific genotypes were noted in 20 samples, all positive by MS, with an overall concordance of κ = 0.945.

Conclusions: The MS high-throughput method, with a processing capacity of 10 × 384 samples within 2 working days and at a consumables cost of about US$2 per sample, performed as well as or better than the comparison method.
Characterisation of zinc-binding domains of peroxisomal RING finger proteins using size exclusion chromatography/inductively coupled plasma-mass spectrometry
Authors: Koellensperger Gunda , Daubert Simon , Erdmann Ralf , Hann Stephan , Rottensteiner Hanspeter
Published: November 2007

We determined the zinc binding stoichiometry of peroxisomal RING finger proteins by measuring sulfur/metal ratios using inductively coupled plasma-mass spectrometry coupled to size exclusion chromatography, a strategy that provides a fast and quantitative overview on the binding of metals in proteins. As a quality control, liquid chromatography-electrospray ionisation-time of flight-mass spectrometry was used to measure the molar masses of the intact proteins. The RING fingers of Pex2p, Pex10p, and Pex12p showed a stoichiometry of 2.0, 2.1, and 1.2 mol zinc/mol protein, respectively. Thus, Pex2p and Pex10p possess a typical RING domain with two coordinated zinc atoms, whereas that of Pex12p coordinates only a single zinc atom.
Differential methylation kinetics of individual target site strands by T4Dam DNA methyltransferase
Authors: Zinoviev Victor V. , Evdokimov Alexey A. , Malygin Ernst G. , Sclavi Bianca , Buckle Malcolm , Hattman Stanley
Published: November 2007

Prokaryote DNA methyltransferases (MTases) of the Dam family (including those of bacteriophages T2 and T4) catalyze methyl group transfer from S-adenosyl-L-methionine (AdoMet), producing S-adenosyl-L-homocysteine (AdoHcy) and methylated adenine residues in palindromic GATC sequences. Dam DNA MTases, as all site-specific enzymes interacting with polymeric DNA, require a mechanism of action that ensures a rapid search for specific targets for catalytic action, during both the initial and subsequent rounds of methylation. The results of pre-steady-state (reaction burst) and steady-state methylation analyses of individual targets permitted us to monitor the action of T4Dam, which has three degrees of freedom: sliding, reorientation and adaptation to the canonical GATC sequence. The salient results are as follows: (i) 40mer substrate duplexes containing two canonical GATC sites showed differential methylation of the potential targets, i.e., T4Dam exhibited a preference for one site/target, which may present the better ‘kinetic trap’ for the enzyme. (ii) Prior hemimethylation of the two sites made both targets equally capable of being methylated during the pre-steady-state reaction. (iii) Although capable of moving in either direction along double-stranded DNA, there are some restrictions on T4Dam reorientation/adaptation on 40mer duplexes.
Cysteine cathepsin non-inhibitory binding partners: modulating intracellular trafficking and function
Authors: Victor Bernadette C. , Sloane Bonnie F.
Published: November 2007

Cysteine cathepsins play a fundamental role in tumor growth, invasion and migration, angiogenesis, and the metastatic cascade. Evidence of their overexpression in a wide array of human tumors has been well documented. Cysteine cathepsins seem to have a characteristic location-function relationship that leads to non-traditional roles such as those in development and pathology. For example, during tumor development, some cysteine cathepsins are found not just within lysosomes, but are also redistributed into presumptive exocytic vesicles at the cell periphery, resulting in their secretion. This altered localization contributes to non-lysosomal functions that have been linked to malignant progression. Mechanisms for altered localization are not well understood, but do include the interaction of cysteine cathepsins with binding partners that modulate intracellular trafficking and association with specific regions on the cell surface.
‘Species’ of peptidases
Authors: Barrett Alan J. , Rawlings Neil D.
Published: November 2007

A good system for the naming and classification of peptidases can contribute much to the study of these enzymes. Having already described the building of families and clans in the MEROPS system, we here focus on the lowest level in the hierarchy, in which the huge number of individual peptidase proteins are assigned to a lesser number of what we term ‘species’ of peptidases. Just over 2000 peptidase species are recognised today, but we estimate that 25 000 will one day be known. Each species is built around a peptidase protein that has been adequately characterised. The cluster of peptidase proteins that represent the single species is then assembled primarily by analysis of a sequence ‘tree’ for the family. Each peptidase species is given a systematic identifier and a summary page of data regarding it is assembled. Because the characterisation of new peptidases lags far behind the sequencing, the majority of peptidase proteins are so far known only as amino acid sequences and cannot yet be assigned to species. We suggest that new forms of analysis of the sequences of the unassigned peptidases may give early indications of how they will cluster into the new species of the future.
Isolation and identification of residual chromophores from aged bleached pulp samples
Authors: Rosenau Thomas , Potthast Antje , Kosma Paul , Suess Hans U. , Nimmerfroh Norbert
Published: November 2007

Three bleached and subsequently aged cellulosic pulps have been analysed for their chromophore content according to the chromophore release and identification (CRI) method. Several chromophores have been unambiguously identified, despite their very low content (ppb range). This is the first report on defined chromophoric structures isolated from bleached pulps. It is also the first application of the CRI method to cellulose I substrates, rather than to cellulose II substrates (fibres) and cellulose derivatives as hitherto performed. A common feature of the chromophores is the 2-hydroxy-[1,4]benzoquinone moiety, which is strongly stabilized by resonance or tautomerism. The structure of the chromophores indicates that oxidised carbohydrate structures act as precursor moieties, which condense upon ageing to the chromophore structures identified.
Paper mill sludge as a component of wood adhesive formulation
Authors: Geng Xinglian , Deng James , Zhang Shu Yin
Published: November 2007

Three major types of paper mill sludge, primary sludge (PS), secondary sludge (SS) and de-inking paper sludge (DPS) were characterized and evaluated as adhesive fillers. Plywood panels were made of formulations with phenol formaldehyde (PF) and sludges. Panels with PF/PS and PF/SS formulations had higher dry and wet shear strengths than those made with PF/Cocob® formulation. All wood failure values were comparable. Dry and wet shear strengths of the panels with PF/DPS formulation were comparable to those of the PF/Cocob® panels (with Cocob® as a commercial filler), but the former displayed a much lower wood failure value. Owing to this fact and its high ash content, DPS was not evaluated further as a potential component of adhesive formulations. Compared with SS, PS resulted in higher dry and wet shear strengths and higher wood failure values. However, granular SS was easier to disperse into the resin component than fibrous PS, and the PF/SS formulation was more easily dispensed on aspen veneer sheets than the PF/PS formulation. SS alone displayed adhesive properties with 0.87 MPa of dry shear strength, but PS alone did not exhibit any bond strength. PS and SS were further evaluated for their general thermal behavior and major functional groups using differential scanning calorimetry and Fourier transform infrared spectrometry, respectively.
Time/temperature equivalence in the dry wood creep response
Authors: Sun Nanjian , Frazier Charles E.
Published: November 2007

Rheology of wood molecular and supramolecular organization has mostly been conducted with dynamic methods, and the application of time/temperature equivalence typically requires plasticizers to observe segmental relaxation. Dry wood rheology offers the experimental advantage of easy moisture control, but only weak secondary relaxations are observed with dynamic methods. Static methods allow for the longer relaxation times in glassy polymers, and these relaxations are strongly stimulated by lower less damaging temperatures. This study describes the application of creep mode time/temperature equivalence to dry yellow-poplar (Liriodendron tulipifera) and southern yellow pine (Pinus spp.). It was found that time/temperature equivalence was valid from 10–170°C, but only for specimens that received a prior 30-min thermal treatment (with minor desiccation) in the range of 100–170°C. The two woods exhibited clear differences in the temperature dependence of the dry wood creep relaxation, and in the sensitivity to free volume manipulation. These findings are believed to reflect polymer structural differences in hardwoods and softwoods indicating that creep mode time/temperature studies of dry wood may be useful for the analysis of xylem polymer behavior.
Neural network prediction of bending strength and stiffness in western hemlock (Tsuga heterophylla Raf.)
Authors: Mansfield Shawn D. , Iliadis Lazaros , Avramidis Stavros
Published: November 2007

The stiffness and strength, modulus of elasticity (MOE) and modulus of rupture (MOR), as well as density, moisture content, microfibril angle and diffraction pattern coefficient of variation of azimuthal intensity profile (ICV) was determined for 259 small clear specimens. These samples represent 38 old- and second-growth western hemlock (Tsuga heterophylla) trees harvested from several sites in coastal British Columbia, Canada. The data were analyzed by classic statistical regression techniques to reveal interrelations among the mechanical properties and the inherent wood properties. Simultaneously, the predictive power of artificial neural networks was evaluated with the same data set by employing several optimization techniques. Regression analysis of wood density and the flexural strength properties resulted in R2 of 0.172 and 0.332 for MOE and MOR, respectively. The most efficient network model proved to be far superior demonstrating correlation coefficients with models for MOE ranging between 0.693 and 0.750, and the corresponding MOR models ranging between 0.438 and 0.561 in all testing phases. It is apparent that neural networks have the potential and capacity to self-train and become powerful adaptive systems that can predict the strength and stiffness of wood samples. The neural network analysis also revealed the importance level of each independent variable on both MOE and MOR properties.
Bending properties of particleboard and MDF layers
Authors: Wilczyński Arnold , Kociszewski Marek
Published: November 2007

The modulus of elasticity in bending and the bending strength of the face and core layer of particleboard and medium density fiberboard (MDF) were determined. Three directions of longitudinal axis of test specimens were considered: the direction of the mat forming, the direction perpendicular to it, and the direction perpendicular to the panel plane. The experiments were carried out on specimens that were prepared with strips of layers separated from the panels and glued into laminated assemblies. The bending properties of the core and face layer of the tested panels differed considerably. The core layer properties were on average more than 4 times smaller for particleboard and almost 3 times smaller for MDF. The relative differences between the bending properties were greater than the differences between the densities of the layers. The bending properties of the layers were almost isotropic in the planes of layers and very strongly anisotropic in the planes perpendicular to layers. The modulus of elasticity of the tested panels was calculated for the axis corresponding to the mat forming direction. The calculations were performed on the basis of the moduli of panel layers and based on the layered system theory. The results were compared with the modulus determined directly for entire panels. The relative difference between the compared moduli was found to be very small for both tested panels.
Gold as an X-ray CT scanning contrast agent: Effect on the mechanical properties of wood plastic composites
Authors: Wang Yi , Muszynski Lech , Simonsen John
Published: November 2007

Wood plastic composites (WPCs) are typically composed of wood particles, thermoplastic polymers and small amounts of additives. Further improvement of WPC technology requires a better understanding of their mechanical performance and durability on the micro level. X-ray computed tomography (CT) and advanced imaging techniques can provide visualization and support characterization of the internal structure, deformation and damage accumulation in WPCs under loading and various environmental exposures. However, both wood and thermoplastics are weakly attenuating materials for X-ray and good contrast between these two components is difficult to obtain. In the present study, chemically inert gold nano-particles and micro-particles were investigated as contrast agents to improve X-ray CT scanning contrast between wood and thermoplastics. The effect of adding 1% (by wt.) gold nano- and micro-particles on the tensile properties of wood/high-density polyethylene composites was addressed. Samples with and without surfactant were tested in tension and scanned on a custom desktop X-ray CT system. It was found that the addition of gold particles did not impair the WPC tensile properties. However, some of the tensile properties were significantly affected if the surfactant was included. Gold micro-particles were shown to disperse well without surfactant and significantly improve the X-ray CT scanning contrast between wood and polymer, while gold nano-particles (without surfactant) did not disperse well and do not contribute to contrast improvement.
Improvement of Pinus pinaster Ait elite trees selection by combining near infrared spectroscopy and genetic tools
Authors: da Silva Perez Denilson , Guillemain Audrey , Alazard Pierre , Plomion Christophe , Rozenberg Philippe , Carlos Rodrigues José , Alves Ana , Chantre Guillaume
Published: November 2007

The first and the second generation of improved maritime pine (Pinus pinaster) have produced gains of up to 30% in stem volume, a reduction of final harvesting age by 10 years and a considerable improvement of stem straightness. The third generation will include wood quality traits for different end-uses, including pulp and fibre properties. To facilitate this goal, near infrared spectroscopy (NIRS) was used to estimate chemical composition with regard to lignin, cellulose, hemicelluloses, and extractive content, and lignin quality with regard to 4-hydroxy-phenylpropane/guaiacylpropane ratio. A total of 960 samples were investigated which were collected from a large number of trees (belonging to 80 families obtained by crossing 18 mothers and 20 fathers; there are 12 trees per family). Good calibration data was obtained between NIRS and wet chemistry methods (R2values higher than 0.9 and good precision of prediction). To complete the NIRS work, kraft cookings in small scale, fibre morphology and microdensitometry investigations were also conducted. Genetic calculations indicated that for a 1% rate of selection on mothers and fathers, genetically induced changes are possible with lignin content (−3.8%), cellulose content (+1.3%), pulp yield (+1.8%), fibre length in pulps (+0.17 mm) and wood density (+50 kg m−3).
Work and Anthropology in Costa Rica: An Orientation
Authors: Weil Jim
Published: November 2007

This introduction to the study of work in Costa Rica develops a frame of reference for articles about (1) the long tradition of “pot hunting,” i.e., looting and commercializing antiquities; (2) the diverse traditions of artisan work with wood; (3) ambiguities about indigenous identity in the emergence of new livelihoods in response to cultural tourism; and (4) the attainment of “professional” status in a direct‐sales network of an international company promoting products claimed to enhance health. The articles explore different settings, time periods and other dimensions of work, yet they share a sense of the importance of respecting a component of the national ethos dedicated to the enjoyment of life, pura vida, which encompasses satisfying and sustainable livelihoods. Beyond the researchers' findings, treated separately and comparatively, their underlying assumptions and approaches also reveal distinctive aspects of the “work of anthropology” in Costa Rica.
The Next Upsurge: Labor and the New Social Movements
Authors: Gabriel Jackie
Published: November 2007

The Next Upsurge: Labor and the New Social Movements. Dan Clawson. Ithaca, NY: Cornell University Press, 2003.
The Evidence for Use of Human Milk in Very Low-birthweight Preterm Infants
Authors: Patel Aloka L. , Meier Paula P. , Engstrom Janet L.
Published: November 2007

Many small and recently larger studies demonstrate the protective effects of human milk feedings for very low-birthweight (VLBW) infants, resulting in decreased morbidities. These benefits are due to the many unique properties of human milk that function synergistically to protect the infant from infectious, inflammatory, and oxidant injury. However, few VLBW infants in the United States receive maternal milk due to significant economic and social barriers. Additionally, the current research has not identified accurately the amount and timing of human milk feedings that provide maximal protection, which would enable optimal use of this scarce resource. Although the benefits of human milk feedings in VLBW infants have been demonstrated clearly, issues that remain unclear include dosing considerations and the economic implications of providing human milk feedings.
Evidence-based Practices to Promote Exclusive Feeding of Human Milk in Very Low-birthweight Infants
Authors: Meier Paula P. , Engstrom Janet L.
Published: November 2007

Recent studies suggest a dose-response relationship between the amount of fortified human milk (FHM) received by very low-birthweight and extremely low-birthweight infants and protection from select prematurity-specific morbidities. However, the feeding of high doses of FHM in this population often is precluded by insufficient maternal milk volume and the replacement of FHM feedings with calorie-dense infant formulas to achieve adequate weight gain. This article reviews the evidence for preventing, diagnosing, and treating insufficient maternal milk volume and slow infant weight gain while receiving FHM and highlights the utility of incorporating technologies from human milk science, such as maternal milk volume records and the creamatocrit procedure, into routine neonatal intensive care unit practice.
Myths and Dogmas in Neonatal Gastroenterology and Nutrition
Authors: Neu Josef
Published: November 2007

Widespread clinical care practices in neonatology are based on tradition rather than a solid scientific foundation. For example, the concept that parenteral nutrition is totally adequate in neonates and that enteral nutrition can be withheld for prolonged periods may be incorrect; several adverse consequences are associated with a lack of enteral nutrients. The interaction between the intestinal microbiome and the innate and adaptive immune system suggest that general administration of broad-spectrum antibiotics to very low-birthweight infants shortly after birth may be associated with both short- and long-term potential adverse effects. Finally, factors other than food intake may be related to the development of the metabolic syndrome, suggesting that avoidance of “aggressive” nourishment shortly after birth and “catch-up” growth may not be appropriate.
Severe Varicella Caused by Varicella-Vaccine Strain in a Child With Significant T-Cell Dysfunction
Authors: Jean-Philippe Patrick , Freedman Abigail , Chang Mary Wu , Steinberg Sharon P. , Gershon Anne A. , LaRussa Philip S. , Borkowsky William
Published: November 2007

In March 1995, the US Food and Drug Administration approved a live attenuated varicella vaccine for use in healthy children 12 months to 12 years old. We report here an 18-month-old girl with cell-mediated immunodeficiency who developed a severe vaccine-associated rash and clinical evidence of vaccine-associated pneumonia 1 month after inadvertent receipt of varicella vaccine.
Healing of Nonhymenal Genital Injuries in Prepubertal and Adolescent Girls: A Descriptive Study
Authors: McCann John , Miyamoto Sheridan , Boyle Cathy , Rogers Kristen
Published: November 2007

OBJECTIVE. The objective of this study was to identify the healing process and outcome of nonhymenal injuries in prepubertal and pubertal girls.

METHODS. This multicenter, retrospective project used photographs to document the healing process and outcome of nonhymenal genital injuries in 239 prepubertal and pubertal girls whose ages ranged from 4 months to 18 years.

RESULTS. The genital injuries sustained by the 113 prepubertal girls consisted of 21 accidental or noninflicted injuries, 73 injuries secondary to abuse, and 19 injuries of unknown cause. All 126 pubertal girls were sexual assault victims. These nonhymenal genital injuries healed at various rates depending on the type and severity. There was no statistical difference in the rate of healing between the 2 groups. Abrasions disappeared by the third day after injury. Edema was no longer present by the fifth day. Ecchymosis (bruising) resolved within 2 to 18 days depending on the severity. One prepubertal girl still had a labial hematoma at 2 weeks. Submucosal hemorrhages of the vestibule and fossa navicularis resolved between 2 days and 2 weeks. Petechiae and blood blisters proved useful for approximating the age of an injury. Petechiae were gone by 24 hours, whereas blood blisters were detected at 30 days in a prepubertal girl and 24 days in a pubertal girl. The depth of a laceration determined the time required for it to heal. Superficial vestibular lacerations seemed healed in 2 days, whereas deep perineal lacerations required up to 20 days. The appearance of new blood vessel formation was detected only in prepubertal girls, whereas scar tissue formation occurred only after a deep laceration in both groups.

CONCLUSIONS. The majority of these nonhymenal genital injuries healed with little or no evidence of previous trauma. The time required for resolution varied by type, location, and severity.
Ontogeny of Bilirubin-Binding Capacity and the Effect of Clinical Status in Premature Infants Born at Less Than 1300 Grams
Authors: Bender George Jesse , Cashore William James , Oh William
Published: November 2007

BACKGROUND. Bilirubin is toxic to the brain and enters the brain in unbound form. Serum unconjugated, unbound bilirubin may be a good predictor of bilirubin encephalopathy. Unbound bilirubin levels may depend on the bilirubin-binding capacity of albumin, which has not been described for neonates of <28 weeks’ gestation.

OBJECTIVE. The purpose of this work was to determine the ontogeny of bilirubin-binding capacity and the effect of clinical status in very preterm neonates.

METHODS. A total of 152 neonates (23–31 weeks’ gestational age; 440–1300 g) were enrolled prospectively. At 5 days of age, total serum bilirubin and unbound bilirubin were measured with the unbound bilirubin-A1 analyzer (Arrows Co, Osaka, Japan) and albumin with the Bromocresol-purple method. Scatchard plots were used to estimate bilirubin-binding affinity and capacity. Clinical status for each infant was rated as high, moderate, or low risk by using a modified Score for Neonatal Acute Physiology model. Low risk was considered clinically stable.

RESULTS. Unbound bilirubin has a significant, direct correlation to total bilirubin and is greater in unstable than in stable neonates. For the entire cohort, bilirubin-binding capacity had a direct relationship to gestational age. The bilirubin-binding capacities of infants in the low- and high-risk groups also had a direct relationship to gestational age. Bilirubin-binding capacity was greater in the low-risk group (20.8 ± 4.6 mg/dL; 356 ± 79 μmol/L) than in the moderate- (17.8 ± 3.5 mg/dL; 304 ± 60 μmol/L) or high- (17.3 ± 3.4 mg/dL; 296 ± 58 μmol/L) risk groups. Bilirubin-binding affinity did not differ by clinical risk status or gestational age.

CONCLUSIONS. In very preterm, very low birth weight infants, bilirubin-binding capacity is directly proportional to gestational age. Bilirubin-binding capacity is lower and unbound bilirubin higher in unstable than in stable neonates. These data may be useful in guiding the management of hyperbilirubinemia in very low birth weight infants.
Impact of Computerized Prescriber Order Entry on the Incidence of Adverse Drug Events in Pediatric Inpatients
Authors: Holdsworth Mark T. , Fichtl Richard E. , Raisch Dennis W. , Hewryk Adrianne , Behta Maryam , Mendez-Rico Elena , Wong Cindy L. , Cohen Jennifer , Bostwick Susan , Greenwald Bruce M.
Published: November 2007

OBJECTIVES. This study was conducted to determine the impact of a computerized physician order entry system with substantial decision support on the incidence and types of adverse drug events in hospitalized children.

METHODS. A prospective methodology was used for the collection of adverse drug events and potential adverse drug events from all patients admitted to the pediatric intensive care and general pediatric units over a 6-month period. Data from a previous adverse drug event study of the same patient care units before computerized physician order entry implementation were used for comparison purposes.

RESULTS. Data for 1197 admissions before the introduction of computerized physician order entry were compared with 1210 admissions collected after computerized physician order entry implementation. After computerized physician order entry implementation, it was observed that the number of preventable adverse drug events (46 vs 26) and potential adverse drug events (94 vs 35) was reduced. Reductions in overall errors, dispensing errors, and drug-choice errors were associated with computerized physician order entry. There were reductions in significant events, as well as those events rated as serious or life threatening, after the implementation of computerized physician order entry. Some types of adverse drug events continued to persist, specifically underdosing of analgesics. There were no differences in length of stay or patient disposition between preventable adverse drug events and potential adverse drug events in either study period.

CONCLUSIONS. This study demonstrated that a computerized physician order entry system with substantive decision support was associated with a reduction in both adverse drug events and potential adverse drug events in the inpatient pediatric population. Additional system refinements will be necessary to affect remaining adverse drug events. Preventable events did not predict excess length of stay and instead may represent a sign, rather than a cause, of more complicated illness.
Neonatal Hyperparathyroidism and Pamidronate Therapy in an Extremely Premature Infant
Authors: Fox Lisa , Sadowsky Joel , Pringle Kevin P. , Kidd Alexa , Murdoch Jean , Cole David E.C. , Wiltshire Esko
Published: November 2007

We describe the use of pamidronate to control marked hypercalcemia in an extremely premature infant with neonatal hyperparathyroidism that resulted from an inactivating mutation (R220W) of the calcium-sensing receptor. Despite improvement in bone mineralization and subsequent parathyroidectomy with normalization of the serum calcium level, the combination of chronic lung disease, osteomalacia, and poor thoracic cage growth ultimately proved fatal. Pamidronate therapy seems to be safe in the short-term and effective in helping control hypercalcemia even in the very premature infant, allowing for planned surgical intervention when it becomes feasible.
Violent Television Viewing During Preschool Is Associated With Antisocial Behavior During School Age
Authors: Christakis Dimitri A. , Zimmerman Frederick J.
Published: November 2007

OBJECTIVE. The effect of violent television programming on preschoolers’ behaviors is poorly understood. The objective of this study was to test the hypothesis that exposure to violent television viewing when children are 2 to 5 years of age would be associated with antisocial behavior at ages 7 to 10.

METHODS. Data were derived from the Panel Study of Income Dynamics. Our primary outcome was being in the 88th percentile of the Behavioral Problem Index antisocial subdomain. Our primary predictor was exposure to violent screen content.

RESULTS. Data were available for 184 boys and 146 girls at both time periods. Adjusting for baseline Behavioral Problem Index scores and age, parental education, maternal depression, and cognitive and emotional support, violent television programming was associated with an increased risk for antisocial behavior for boys but not for girls. Neither educational nor nonviolent programming was associated with increased risk for boys or girls.

CONCLUSIONS. Viewing of violent programming by preschool boys is associated with subsequent aggressive behavior. Modifying the content that is viewed by young children may be warranted.
Size at Birth and Motor Activity During Stress in Children Aged 7 to 9 Years
Authors: Schlotz Wolff , Jones Alexander , Phillips Naomi M.M. , Godfrey Keith M. , Phillips David I.W.
Published: November 2007

OBJECTIVES. Small size at birth is linked with metabolic and cardiovascular disease. There is increasing evidence that it is also linked with physiologic stress responses and abnormal behavior, in particular, symptoms of hyperactivity. Therefore, we investigated associations between size at birth and motor activity during psychosocial stress.

METHODS. In 123 children aged 7 to 9 years, we examined the relations of birth weight, head circumference, length, and ponderal index at birth with motor activity on exposure to both stress and nonstress situations. Videos were recorded while the children performed a story and a math task in front of an audience (stress) and watched a movie (nonstress); motor activity was defined as lifting or tilting of a foot.

RESULTS. Children who had had a smaller head circumference at birth demonstrated greater motor activity during the stress test. There were marked gender differences in the results. In boys, lower birth weight, head circumference, and ponderal index were associated with greater motor activity during the stress test but not associated with motor activity during the nonstress situation. The findings remained significant when potential confounding variables were controlled for. There were no associations in girls.

CONCLUSIONS. The findings suggest long-term effects of an adverse fetal environment on the behavioral stress response in boys and parallel similar gender-specific effects on different stress response systems in humans and animals. The results could reflect permanent alterations of dopaminergic neurotransmission and have implications for the etiology of clinical hyperactivity.
Shorter Sleep Duration Is Associated With Increased Risk for Being Overweight at Ages 9 to 12 Years
Authors: Lumeng Julie C. , Somashekar Deepak , Appugliese Danielle , Kaciroti Niko , Corwyn Robert F. , Bradley Robert H.
Published: November 2007

OBJECTIVE. The potential association between short sleep duration or sleep problems and childhood overweight has not been well described. The objective of this study was to test the independent associations of sleep duration and problems with overweight risk in children.

METHODS. Data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development were analyzed. In 3rd and 6th grades, sleep duration and problems were obtained by maternal report, and height and weight were measured, with overweight defined as a BMI of ≥95th percentile for age and gender. Logistic regression evaluated the association of sleep duration and problems with overweight at 6th grade cross-sectionally adjusting for gender, race, and maternal education. Additional covariates tested individually included the level of chaos at home, the quality of the home environment, the lax-parenting subscale score of the Raising Children Checklist, and the Child Behavior Checklist internalizing and externalizing subscale scores. Logistic regression also evaluated the relationship of sleep duration at 3rd grade and overweight at 6th grade, adjusting for gender, race, maternal education, and the child's BMI z score in 3rd grade.

RESULTS. Of 785 children, 50% were male, 81% were white, and 18% were overweight in 6th grade. Shorter sleep duration in 6th grade was independently associated with a greater likelihood of overweight in 6th grade. Shorter sleep duration in 3rd grade was also independently associated with overweight in 6th grade, independent of the child's weight status in 3rd grade. Sleep problems were not associated with overweight.

CONCLUSION. One preventive approach to overweight may be to ensure adequate sleep in childhood.
Associations Between Content Types of Early Media Exposure and Subsequent Attentional Problems
Authors: Zimmerman Frederick J. , Christakis Dimitri A.
Published: November 2007

OBJECTIVE. Television and video/DVD viewing among very young children has become both pervasive and heavy. Previous studies have reported an association between early media exposure and problems with attention regulation but did not have data on the content type that children watched. We tested the hypothesis that early television viewing of 3 content types is associated with subsequent attentional problems. The 3 different content types are educational, nonviolent entertainment, and violent entertainment.

METHODS. Participants were children in a nationally representative sample collected in 1997 and reassessed in 2002. The analysis was a logistic regression of a high score on a validated parent-reported measure of attentional problems, regressed on early television exposure by content and several important sociodemographic control variables.

RESULTS. Viewing of educational television before age 3 was not associated with attentional problems 5 years later. However, viewing of either violent or non-violent entertainment television before age 3 was significantly associated with subsequent attentional problems, and the magnitude of the association was large. Viewing of any content type at ages 4 to 5 was not associated with subsequent problems.

CONCLUSIONS. The association between early television viewing and subsequent attentional problems is specific to noneducational viewing and to viewing before age 3.