bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of wet-pockets on the surface of Tsuga heterophylla (Raf.) Sarg. by near infrared (NIR) spectroscopy
Authors: Watanabe Ken , Hart Foster , Mansfield Shawn D. , Avramidis Stavros
Published: December 2009

Multivariate statistical models capable of rapidly and accurately predicting the surface moisture content in Tsuga heterophylla were developed based on near infrared (NIR) spectra of small specimens precisely conditioned within the hygroscopic range. In an initial research phase, the applicability of NIR as predictor of surface moisture was investigated. The first derivative spectra in the range of 1300–2100 nm yielded the best results. The partial least squares regression (PLS-1) model had coefficient of determination (R2) of 0.98, root mean square error of cross validation (RMSECV) of 0.97%, root mean square error of prediction (RMSEP) of 1.05%, and ratio of performance to deviation (RPD) of 7.25. In a subsequent phase, an inline pilot-plant NIR system combined with this PLS-1 model was constructed. The prediction ability of the NIR system was tested with line speeds of 0, 100, 200, and 400 mm s-1 on kiln-dried full-length lamination boards classified as “wets” after conventional kiln drying. In a calibrated range of moisture content (0–25.4%), the NIR system demonstrated R2 values of 0.79 and 0.74, RMSEP values of 3.13 and 3.28, and RPD values of 2.18 and 1.67 at a line speed of 0 and 100 mm s-1, respectively, regardless of the presence of knots and surface roughness. These results demonstrate that the NIR system at a line speed of 0–100 mm s-1 could be used to provide entire surface moisture distribution and to detect local moisture peaks that indicate surface wet-pockets in kiln-dried lumber destined for lamination.
Cellular distribution of coniferin in differentiating xylem of Chamaecyparis obtusa as revealed by Raman microscopy
Authors: Morikawa Yohei , Yoshinaga Arata , Kamitakahara Hiroshi , Wada Munehisa , Takabe Keiji
Published: December 2009

Cellular distribution of coniferin in differentiating xylem of Japanese cypress (Chamaecyparis obtusa) was analyzed by Raman microscopy. Small blocks were collected from differentiating xylem, frozen, cut on their surface with a sliding microtome, and then freeze-dried. Scanning electron microscopy showed numerous needle-like deposits in the tracheid lumina from the beginning of the S1 layer formation to the S2 layer-forming stage. The Raman spectrum of the deposits in the tracheid lumen was similar to that of coniferin. The presence of coniferin in a water extract from differentiating xylem was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy and 1H- and 13C-nuclear magnetic resonance spectra. Differential Raman spectra taken from samples before and after washing with water and dehydration in an ethanol showed that developing secondary walls contained coniferin during the S2 layer-forming stage and also after S3 layer formation. In contrast, coniferin was detected in the cell corner middle lamella during the S2 layer-forming stage, and the differential spectra were different from that of coniferin after S3 layer formation. The differential spectrum in this stage was similar to that of a dehydrogenation polymer of coniferyl alcohol prepared by the “zulauf” method (bulk polymerization). These results suggest that free lignin oligomers of the type bulk polymerizate might exist in the cell corner middle lamella during the S3 layer-forming stage and can be removed from specimens during washing and dehydration. The results can be interpreted in a way that no such oligomer exists in the secondary wall during the same stage owing to endwise addition of monolignols (in analogy to a “zutropf” polymerization).
Drying Response of Wood-Frame Construction: Laboratory and Modeling
Authors: Maref W. , Lacasse M. A.
Published: December 2009

Recent research in the assessment of hygrothermal response of building enclosures focuses on both laboratory experimentation and modeling in which the results from both processes are compared. Evidently such type of studies can potentially offer useful information regarding the benchmarking of models and related methods to assess hygrothermal performance of wall assemblies. This paper reports on experimental results and the use of an advanced hygrothermal computer model called hygIRC to assess the hygrothermal response of various components in wood-frame wall assemblies when subjected to nominally steady-state environmental conditions. There was interest in obtaining information on the drying rates of wall components, in particular, oriented strand board (OSB), featuring several different types of membrane in contact with OSB given that such results could provide direct evidence of the degree to which membranes may retain moisture and affect moisture migration. On this basis, the drying responses of mid-scale specimens of approximately (0.8×1 m2) and full-scale specimens (2.44×2.44 m2) were assessed in a series of experiments undertaken in a controlled laboratory setting. The results were subsequently used to help benchmark simulation results obtained from hygIRC in which a comparison is made between experimental and simulation results.
Experimental Assessment of Hygrothermal Properties of Wood-Frame Wall Assemblies—Moisture Content Calibration Curve for OSB Using Moisture Pins
Authors: Maref W. , Lacasse M. A. , Booth D.
Published: December 2009

As part of a research program to establish the hygrothermal response of wood-frame wall assemblies to varying climate conditions, a series of drying experiments was performed in a programmable environmental chamber used to replicate exterior climatic conditions. In these experiments, bulk moisture content of the assembly was measured using a weighing system, and as well, measurements of local moisture content of oriented strand board (OSB) sheathing were taken with the use of electrical resistance moisture pin pairs. The local moisture content of the OSB was based on the relationship between moisture content and electrical resistance determined from a series of controlled laboratory experiments on OSB specimens of the same type and thickness. This paper reports on the results from experimental tests on seven small-size OSB specimens to establish the correlation between electrical resistance and the moisture content of the OSB. The process required the installation of several moisture pin pairs at different locations on and depths in the OSB. The weights of specimens together with resistance measurements taken across each pair of moisture pins were continuously monitored and results captured on a data acquisition unit. Details are provided in regard to electrical resistance measurements, the data acquisition unit, and method of weighing specimens. The results of the tests provided a simple equation to correlate moisture content of OSB to electrical resistance measurements using moisture pins pairs and as well correlation to moisture measurements using commercially available moisture metre. Given that moisture reading results obtained from commercially available moisture metres typically correlate to a specific wood species, the work completed in these experimental tests can be used to determine moisture contents in OSB from moisture metre readings.
Predicting Fire Behavior of Composite CFT Columns Using Fundamental Section Behavior
Authors: Hong Sangdo , Varma Amit H.
Published: December 2009

This paper presents the development and verification of a fiber-based analytical approach for predicting the behavior of concrete filled steel tube (CFT) columns subjected to constant axial load and standard fire loading. The approach consists of three parts: (1) Two-dimensional heat transfer analysis, (2) section moment-curvature analysis, and (3) column inelastic buckling analysis using modified Newmark’s method. The analytical approach was verified by using it to predict (1) the thermal and structural behavior of CFT column specimens subjected to standard fire tests by different researchers and (2) the fundamental moment-curvature behavior of CFT beam-column specimens subjected to special (non-standard) fire tests conducted by the authors. The analytical approach predicts the fundamental moment-curvature behavior of CFT beam-column specimens and the standard fire behavior of CFT column specimens with reasonable accuracy. The analytical results also compare favorably with the overall behavior and stress states predicted by three-dimensional finite element analyses conducted earlier by the authors. The fiber-based analytical approach is recommended for modeling and predicting the standard, non-standard, or realistic fire behavior of CFT columns and beam-columns under various loading, heating, and boundary conditions.
Comparisons of Temperature and Heat Flux in Furnaces Controlled by Different Types of Temperature Sensors
Authors: Sultan Mohamed A.
Published: December 2009

This paper presents and discusses furnace temperature and heat flux measurements in a fire resistance floor furnace controlled by ASTM shielded thermocouple probes, ISO 834 plate thermometers, directional flame thermometers, and bare bead thermocouples. Comparisons of furnace temperature measurements, temperature sensor time constants; incident heat flux and measured versus predicted incident heat flux are presented.
Application of Advanced Master Curve Approaches to the EURO Fracture Toughness Data Set
Authors: Lucon Enrico , Scibetta Marc
Published: December 2009

The so-called EURO data set is the largest set ever assembled, consisting of fracture toughness results obtained in the ductile-to-brittle transition region. It was the outcome of a large project, sponsored by the European Union, which involved ten European laboratories in the second half of the 1990s. Several post-project investigations have identified one of the blocks from which specimens were extracted (block SX9) as macroscopically inhomogeneous and significantly tougher than the remaining blocks. In this paper, the variability of block SX9 has been investigated using the conventional master curve (MC) methodology and some recent MC extensions, namely, the SINTAP (structural integrity assessment procedure) lower tail, the single point estimation, the bi-modal MC, and the multi-modal MC. The basic MC method is intended for macroscopically homogeneous ferritic steels only, and the alternative approaches have been developed for the investigation of inhomogeneous materials. Therefore, these methods can be used to study the behavior of block SX9 within the EURO data set. It has been found that the bi-modal and multi-modal MC approaches are quite effective in detecting the “anomaly” represented by block SX9 but only when analyses are performed on data sets of comparable size.
Importance of Residual Stresses and Surface Roughness regarding Fatigue of Titanium Forgings
Authors: Oberwinkler B. , Riedler M. , Eichlseder W.
Published: December 2009

This paper presents the results of a long-term research program aimed at developing qualitative and quantitative design guidelines for the use of mechanical surface treatments designed to improve the fatigue life of structural components. High cycle fatigue tests were performed on planar four-point bending specimens derived from Ti-6Al-4V pancake forgings with a mill-annealed microstructure. The high cycle fatigue behavior of specimens with different surface conditions (as-forged and machined) in both an unpeened and a shot peened state was compared. In order to assess the fatigue failure mechanisms, detailed investigations of the surface layers were carried out. The as-forged surface state exhibits a stress distribution with significant compressive stresses near the surface, resulting in equilibrium tensile stresses in the depth. When the tensile stresses were exposed by machining a bordering surface, a distinct decrease in the fatigue strength was observed. In such cases, a shot peening treatment was shown to improve the fatigue strength. Square edges lead to a decrease in the fatigue strength, which could be aggravated by shot peening.
Prediction of Quench-Hardness within the Whole Volume of Axially Symmetric Workpieces of Any Shape
Authors: Liščić Božidar , Singer Saša , Smoljan Božo
Published: December 2009

A quench probe, based on the Temperature Gradient method was used to measure and record cooling curves when quenching real axially symmetric workpieces of any complex shape in liquid quenchants. Calculation of relevant heat transfer coefficients is based on the cooling curve measured just below surface of the cylindrical probe of 50-mm diameter. A two-dimensional computer program, based on the cooling time from 800°C to 500°C (t8/5), and the Jominy hardenability curve of the steel grade in question, is used to predict the hardness distribution within the whole volume of the workpiece, all at once, which is a unique feature of this method.
Group Acceptance Sampling Plans for Pareto Distribution of the Second Kind
Authors: Aslam Muhammad , Mughal Abdur Razzaque , Ahmad Munir , Yab Zafar
Published: December 2009

In this paper, we propose a group acceptance sampling plan (GASP) for truncated life tests when the lifetimes of items follow the Pareto distribution of the second kind. The minimal group size, the operating characteristic value, and the minimal ratio of the true mean life to the specified mean life regarding the proposed GASPs are found, and some of them are tabulated. An example is given for illustration.
Loading Rate Effect on the Master Curve Reference Temperature, T, for the A533 B Material
Authors: Hernández Rogelio , Romero Jesús , Vázquez Salvador , Santillán Manuel , Scibetta Marc
Published: December 2009

The National Institute for Nuclear Research in Mexico participated in the international research project “Master Curve Approach to Monitor the Fracture Toughness of Reactor Pressure Vessel in Nuclear Power Plants” coordinated by the International Atomic Energy Agency (IAEA), where the loading rate effect on the Master Curve reference temperature, T0, was investigated. The experimental program consisted in quasi-static and dynamic fracture toughness testing of precracked Charpy specimens on the IAEA reference reactor pressure vessel steel Japanese reference quality (JRQ) (A533 Grade B Class 1), which was analyzed with the Master Curve methodology. The tests were carried out in displacement control at two temperatures, −70 and −60°C, and at three load rates, dK/dt=0.1, 1, and 10 MPa√m/s. The determined reference temperatures, T0 (0.1 MPa√m/s)=−73.6±6.4°C, T0 (1 MPa√m/s)=−63.3±5.4°C, and T0 (10 MPa√m/s)=−50.3±5°C, are similar to those obtained by other laboratories [IAEA Second Meeting on Master Curve to Monitor the Fracture Toughness of RPVs in NPPs, November 2006, Dresden, Germany]. The shift in T0 within the quasi-static loading rate interval (0.1–2 MPa√m/s) recommended by ASTM E1921-05 [“Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transistion Range,” Annual Book of ASTM Standards, Vol. 03.01, ASTM International, West Conshohocken, PA.] is 14.4°C and the shift in T0 between decades of dK/dt on logarithmic scale is 11°C. The empirical relation proposed by Wallin [“Effect of Strain Rate on the Fracture Toughness Reference Temperature T0 for Ferritic Steels,” Recent Advances in Fracture, R. K. Mahidhara et al., Eds., The Minerals, Metals and Materials Society, 1997, pp. 171–182] predicts very well the shift in T0 in the quasi-static loading regime (0.1–2 MPa√m/s). This work provides experimental support to limit the quasi-static loading rate interval in ASTM E1921.
Study of Underground Oil-Gas Pipeline Corrosion Pits Estimation Based on MFL Inspection Method
Authors: Jiang Qi
Published: December 2009

The paper presents a new approach for detection of oil-gas pipeline corrosion pit defects in which pipeline magnetic flux leakage (MFL) detection system is adopted. To test the new approach, some artificial pits are fabricated on the surface of oil-gas pipes to simulate different pits happening in practice. The interference eliminating method is introduced for compensation of defected MFL field and helping map extraction from the background. Both qualitative and quantitative methods of identifying erosion pit defects are described in the paper.
Molecular Dynamics Simulation of Interfacial Thermal Resistance Between a (10,10) Carbon Nanotube and SiO2
Authors: Ong Zhun-Yong , Pop Eric
Published: December 2009

Understanding thermal transport between carbon nanotubes (CNTs) and dielectric substrates is important both for nanoscale thermal management and CNT device applications. We investi-gate thermal transport between a (10,10) CNT and an SiO2 substrate through non-equilibrium classical molecular dynamics (MD) simulations. The thermal boundary conductance (TBC) is computed by setting up a temperature pulse in the CNT and monitoring its relaxation. The TBC is found to scale nearly linearly with temperature between 200�600 K, where a quantum correction is applied to the CNT heat capacity through its phonon density of states. However, the TBC ap-pears most sensitive to the strength the CNT-substrate interaction, which linearly modulates it between 0.05�0.30 WK-1m-1, in the range suggested by recent experimental data.
Boltzmann Transport Equation Simulation of Semiconductor Interfacial Heat Transfer Based on Input from the Atomistic Green�s Function Method
Authors: Huang Zhen , Singh Dhruv , Murthy Jayathi , Fisher Timothy
Published: December 2009

The Boltzmann transport equation (BTE) had been successfully used to predict phonon transport in semiconductors including silicon and germanium. However, in a composite system, the method requires external inputs to include accurate boundary conditions at internal interfaces. The atomistic Green's function (AGF) method is particularly useful for addressing interfacial heat transfer problems. In this paper, phonon transmission functions derived using the AGF method are incorporated in a non-gray BTE calculation of phonon transport in a relaxation time approximation. A Landauer-type heat flux is computed at the interface using the transmission function and the lattice temperatures on either side of the interface to compute distribution functions. The formulation is applied to a Si/Ge interface and the dependence of the effective thermal conductivity of the composite medium is investigated as a function of domain length.
Infant Weaning Methods: An Intergenerational View from Igbo-Ora Nigeria
Authors: Titiloye Musibau A. , Brieger William R.
Published: December 2009

This study documents and compares the methods by which mothers and grandmothers feed children under 2 years of age in a southwest Nigerian town and the factors which influence their choice of weaning methods. The study was exploratory in design and stratified sampling was done to select respondents from all six wards of the town studied. Two hundred and forty mothers with children under 2 years of age and 246 grandmothers were interviewed. Data analysis was done using EPI INFO Software. Mothers were more likely to have used feeding bottles than grandmothers, while the reverse was true for hand- or forced-feeding. Although most women had used cups and spoons to feed their children, this was more common among current mothers. Over three-quarters of mothers said there were dangers associated with forced-feeding. Grandmothers perceived more social support and encouragement to practice hand-feeding than mothers, while the opposite was true for bottle-feeding. Both groups felt equally encouraged to use cups and spoons. In conclusion, child feeding methods in Igbo-Ora town of Oyo State may be changing with succeeding generations. Forced-feeding appears to be less popular among mothers, and grandmothers are using cups and spoons with feeding bottles. The current generation of mothers in Igbo-Ora would benefit from health education to reinforce safe ways of feeding their children.
Private Sector Response to HIV/AIDS in Tanzania
Authors: Terry Paul E.
Published: December 2009

This study assessed HIV/AIDS prevention practices used by employers in Tanzania. The study also aimed to provide a feasibility analysis of the readiness for HIV/AIDS prevention and other employee health promotion, disease prevention and management interventions within the private sector in Tanzania and to inform emerging scientific literature on the prevalence and composition of employee health education programs in developing countries. Responses to a questionnaire were obtained via structured, face-to-face interviews during visits with company leaders at their workplaces in Tanzania. The survey was conducted from January to March of 2008. It was found that most companies (82%) offer some form of assistance for employees living with HIV/AIDS and other chronic health conditions, and most (73%) also offered HIV/AIDS prevention programs. Use of peer educators was a common feature of HIV prevention efforts. Companies commonly provided free condoms for men (64%); somewhat fewer (55%) provide female condoms. The majority of companies (72%) had a written HIV/AIDS policy. The high rates of program offerings for employees suggest that employers have adopted HIV/AIDS prevention programs, though the wide variability in program offerings indicates employers' beliefs vary concerning the impact of programs, health benefits, and policies.
Dynamics of Health Behavior regarding Hospital Waste Management in Dhaka, Bangladesh: A Dysfunctional Health Belief Model
Authors: Amanullah A. S. M. , Uddin Jalal
Published: December 2009

This article examined the usefulness of the Health Belief Model (HBM) and other confounding factors in determining health behavior of individuals involved in hospital waste management and tested four components of HBM in relation to demographic variables, knowledge, and occupational practices of the respondents. The study revealed that the waste pickers had a lower level of knowledge, attitude, and safe practices than nurses and sweepers. Perceived Susceptibility and Perceived Severity were moderately associated with safe occupational practices among the respondents ( p < 0.05). In addition, respondents with higher levels of education and income were more likely to have higher levels of Perceived Susceptibility, Severity, and Benefits. The study findings indicate that individuals with greater economic vulnerability might be at greater risk for not using proper protective measures in handling or picking hospital wastes in Bangladesh.
Network Effects in Infrastructure Regulation: Principles and Paradoxes
Authors: Brennan Timothy J.
Published: December 2009

Among the many crucial issues in infrastructure regulation has been how to handle network effects. These can both cause monopoly and complicate the management of partial transitions to competition in telecommunications and electricity. The recent global financial crisis itself reflects network effects. Reviewing the variety of definitions, manifestations, and policy consequences of network effects, in sectors both traditionally regulated and outside such regulation, can promote understanding of when networks should be regulated, what about them should be regulated, who should do the regulating  and why we should intervene.
Econometric TFP Targets, Incentive Regulation and the Ontario Gas Distribution Industry
Authors: Lowry Mark N. , Getachew Lullit
Published: December 2009

We present a price cap mechanism, which features an external standard, constructed to elicit efficient utility performance. We focus on a method for setting the external standard, which is usually based on industry total factor productivity (TFP), when 'peer' data are not readily available. The procedure is based on an econometric cost model and externalizes the performance target or TFP by using a combination of industry and individual utility data. To highlight the importance of the method, we profile the approach that was considered and partly adopted in the current incentive regulation plan of Ontario's gas distribution industry.
Intergenerational Mobility of Earnings and Income in Japan
Authors: Ueda Atsuko
Published: December 2009

This paper presents estimates on the intergenerational mobility of economic status in Japan. We estimate the intergenerational elasticity of the earnings and income of offspring with respect to parental income using microdata from the 19932004 rounds of the Japanese Panel Survey of Consumers. The estimated intergenerational elasticity using predicted parental income is 0.410.46 for married sons, 0.300.38 for married daughters, and marginally less than 0.30 for single daughters. A downward trend in elasticity is also observed. Quantile regression does not suggest any particular relation between elasticity and quantiles. A nonlinear analysis of the relation between parental log income and log earnings of offspring illustrates an S-shaped relation for married sons and single daughters, and a linear relation for married daughters.
Thinking about Flexibility
Authors: Villa Mario Díaz
Published: December 2009

This article emphasizes the complexity of the term flexibility and discusses its meanings and political dimensions, along with its expressions or realizations within the field of higher education. It proposes a new principle of flexibility that overcomes an understanding of flexibility within higher education as the mere ability or versatility to adapt itself to the demands of a life regulated by the technological, organizational and economic contingencies of the labor market. Instead, the author suggests a new way of conceptualizing and organizing academic work. This implies redefining the rigid limits within and between teaching and research and between these two practices and their social contexts.
Debates y Desafíos: Reformas de la Educación Superior en Bolivia, una Sociedad Multicultural
Authors: Ostría Gustavo Rodríguez
Published: December 2009

The objective of this work is to analyze from a critical perspective the changes in Bolivian university higher education policies in the last two decades. The 1990s were characterized by neoliberal policies of educational reform in Bolivia. However, a reform perspective from a populist national vision framed by an indigenist ideology has emerged since 2005. The administration of Evo Morales, Bolivia's first aboriginal president, is offering a new discourse on educational reform. However, it is still debatable whether the government is indeed accomplishing the transformations in eduation that its post-neoliberal indigenist discourse promises.
Two Different Organizational Reactions: The University Sector in Argentina and Colombia and the Neoliberal Proposal
Authors: Rabossi Marcelo
Published: December 2009

The neoliberal reform arrived at the market of higher education with the intention of introducing private dynamics into public organizations. Through this strategy, the objective was to improve efficiency by promoting intra- and intersectoral competition. The introduction of performance funding shifted the concept of accountability for expenditures, and now public universities will be accountable for results. The expansion of the private sector as a complementary service to public higher education, and the introduction of tuition fees in non-private institutions, implied a shift of the higher education cost burden that now is shared by parents and students. Argentina and Colombia are two cases that show that not all university sectors in South America have reacted alike when the neoliberal recipe proposed this ‘paradigm shift’. Even when the reform was formally declared in both countries, organizational forces inside the national university in Argentina prevented an in-depth reform. On the other hand, Colombia behaved as one of the best disciples of the neoliberal proposal, where the ‘privatization’ of the university sector found a better place to flourish.
Teletechnology and Higher Education: Does the Approach Matter?
Authors: Buenfil Rosa Nidia
Published: December 2009

This article discusses how international and national understandings of information and communication technology (ICT) and the knowledge economy inform contemporary higher education policies. Acknowledging that national educational policies in Latin America are increasingly influenced by the recommendations of international organizations (e.g. the World Bank, UNESCO, and the Organization for Economic Cooperation and Development), the article provides a clear example of the logics of policy transfer operating in the region. Challenging the interpretations that have tended to stress either the imposition and domination of international meanings and recommendations onto national policies or the total indifference of national reforms vis à vis those international views, this article contends that international policy narratives are locally appropriated and resignified. Specifically, the article deals with the ways in which higher education policy narratives on knowledge and information found in UNESCO's publications are appropriated and reconstituted in Mexico's policy documents.
A Review of Online Learning and its Evolution in Latin America
Authors: Scagnoli Norma
Published: December 2009

The integration of some form of online learning in higher education and its adoption in distance and continuing education has increased exponentially in the last decade. This growth has been consistent in different parts of the world, although its implementation in mainstream educational systems varies according to the economic development of the region. But what is ‘online learning’ and why is it used as a synonym of distance education? This article presents a review that goes through the last 10 years of literature on online learning. It presents the definitions by different authors, and describes its evolution, characteristics, benefits, and use and implementation in education and training. The review concludes with a summary of the development of online learning in Latin America
Diet-Induced Obesity Prevents Interstitial Dispersion of Insulin in Skeletal Muscle
Authors: Kolka Cathryn M. , Harrison L. Nicole , Lottati Maya , Chiu Jenny D. , Kirkman Erlinda L. , Bergman Richard N.
Published: December 2009

OBJECTIVE

Obesity causes insulin resistance, which has been interpreted as reduced downstream insulin signaling. However, changes in access of insulin to sensitive tissues such as skeletal muscle may also play a role. Insulin injected directly into skeletal muscle diffuses rapidly through the interstitial space to cause glucose uptake. When insulin resistance is induced by exogenous lipid infusion, this interstitial diffusion process is curtailed. Thus, the possibility exists that hyperlipidemia, such as that seen during obesity, may inhibit insulin action to muscle cells and exacerbate insulin resistance. Here we asked whether interstitial insulin diffusion is reduced in physiological obesity induced by a high-fat diet (HFD).

RESEARCH DESIGN AND METHODS

Dogs were fed a regular diet (lean) or one supplemented with bacon grease for 9–12 weeks (HFD). Basal insulin (0.2 mU · min−1 · kg−1) euglycemic clamps were performed on fat-fed animals (n = 6). During clamps performed under anesthesia, five sequential doses of insulin were injected into the vastus medialis of one hind limb (INJ); the contralateral limb (NINJ) served as a control.

RESULTS

INJ lymph insulin showed an increase above NINJ in lean animals, but no change in HFD-fed animals. Muscle glucose uptake observed in lean animals did not occur in HFD-fed animals.

CONCLUSIONS

Insulin resistance induced by HFD caused a failure of intramuscularly injected insulin to diffuse through the interstitial space and failure to cause glucose uptake, compared with normal animals. High-fat feeding prevents the appearance of injected insulin in the interstitial space, thus reducing binding to skeletal muscle cells and glucose uptake.
Plasma Membrane Subdomain Compartmentalization Contributes to Distinct Mechanisms of Ceramide Action on Insulin Signaling
Authors: Blouin Cédric M. , Prado Cécilia , Takane Karen K. , Lasnier Françoise , Garcia-Ocana Adolfo , Ferré Pascal , Dugail Isabelle , Hajduch Eric
Published: December 2009

OBJECTIVE

Ceramide is now recognized as a negative regulator of insulin signaling by impairing protein kinase B (PKB)/Akt activation. In different cells, two distinct mechanisms have been proposed to mediate ceramide inhibition of PKB/Akt: one involving atypical protein kinase C zeta (PKCζ) and the other the protein phosphatase-2 (PP2A). We hypothesized that ceramide action through PKCζ or PP2A might depend on plasma membrane (PM) structural organization and especially on caveolin-enriched domain (CEM) abundance.

RESEARCH DESIGN AND METHODS

We have used different PKCζ mutant constructs or the PP2A inhibitor, okadaic acid (OKA), to selectively inhibit PKCζ- and PP2A-dependent pathways in cells expressing different caveolin-1 levels and evaluated the impact of insulin and ceramide on PKB/Akt activity in different PM subdomains.

RESULTS

Although the PKCζ-mediated negative effect of ceramide on insulin-stimulated PKB/Akt was dominant in adipocytes, a ceramide action through PP2A outside CEMs, prevented by OKA, was also unraveled. To test the importance of CEM to direct ceramide action through the PKCζ pathway, we treated 3T3-L1 preadipocytes devoid of CEMs with ceramide and we saw a shift of the lipid-negative action on PKB/Akt to a PP2A-mediated mechanism. In fibroblasts with low CEM abundance, the ceramide-activated PP2A pathway dominated, but could be shifted to a ceramide-activated PKCζ pathway after caveolin-1 overexpression.

CONCLUSIONS

Our results show that ceramide can switch from a PKCζ-dependent mechanism to a PP2A pathway, acting negatively on PKB/Akt, and hence revealing a critical role of CEMs of the PM in this process.
Glucose Induces Pancreatic Islet Cell Apoptosis That Requires the BH3-Only Proteins Bim and Puma and Multi-BH Domain Protein Bax
Authors: McKenzie Mark D. , Jamieson Emma , Jansen Elisa S. , Scott Clare L. , Huang David C.S. , Bouillet Philippe , Allison Janette , Kay Thomas W.H. , Strasser Andreas , Thomas Helen E.
Published: December 2009

OBJECTIVE

High concentrations of circulating glucose are believed to contribute to defective insulin secretion and β-cell function in diabetes and at least some of this effect appears to be caused by glucose-induced β-cell apoptosis. In mammalian cells, apoptotic cell death is controlled by the interplay of proapoptotic and antiapoptotic members of the Bcl-2 family. We investigated the apoptotic pathway induced in mouse pancreatic islet cells after exposure to high concentrations of the reducing sugars ribose and glucose as a model of β-cell death due to long-term metabolic stress.

RESEARCH DESIGN AND METHODS

Islets isolated from mice lacking molecules implicated in cell death pathways were exposed to high concentrations of glucose or ribose. Apoptosis was measured by analysis of DNA fragmentation and release of mitochondrial cytochrome c.

RESULTS

Deficiency of interleukin-1 receptors or Fas did not diminish apoptosis, making involvement of inflammatory cytokine receptor or death receptor signaling in glucose-induced apoptosis unlikely. In contrast, overexpression of the prosurvival protein Bcl-2 or deficiency of the apoptosis initiating BH3-only proteins Bim or Puma, or the downstream apoptosis effector Bax, markedly reduced glucose- or ribose-induced killing of islets. Loss of other BH3-only proteins Bid or Noxa, or the Bax-related effector Bak, had no impact on glucose-induced apoptosis.

CONCLUSIONS

These results implicate the Bcl-2 regulated apoptotic pathway in glucose-induced islet cell killing and indicate points in the pathway at which interventional strategies can be designed.
Duration of Lactation and Incidence of the Metabolic Syndrome in Women of Reproductive Age According to Gestational Diabetes Mellitus Status: A 20-Year Prospective Study in CARDIA (Coronary Artery Risk Development in Young Adults)
Authors: Gunderson Erica P. , Jacobs David R. , Chiang Vicky , Lewis Cora E. , Feng Juanran , Quesenberry Charles P. , Sidney Stephen
Published: December 2009

OBJECTIVE

The objective of the study was to prospectively assess the association between lactation duration and incidence of the metabolic syndrome among women of reproductive age.

RESEARCH DESIGN AND METHODS

Participants were 1,399 women (39% black, aged 18–30 years) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, an ongoing multicenter, population-based, prospective observational cohort study conducted in the U.S. Women were nulliparous and free of the metabolic syndrome at baseline (1985–1986) and before subsequent pregnancies, and reexamined 7, 10, 15, and/or 20 years after baseline. Incident metabolic syndrome case participants were identified according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Complementary log-log models estimated relative hazards of incident metabolic syndrome among time-dependent lactation duration categories by gestational diabetes mellitus (GDM) adjusted for age, race, study center, baseline covariates (BMI, metabolic syndrome components, education, smoking, physical activity), and time-dependent parity.

RESULTS

Among 704 parous women (620 non-GDM, 84 GDM), there were 120 incident metabolic syndrome case participants in 9,993 person-years (overall incidence rate 12.0 per 1,000 person-years; 10.8 for non-GDM, 22.1 for GDM). Increased lactation duration was associated with lower crude metabolic syndrome incidence rates from 0–1 month through >9 months (P < 0.001). Fully adjusted relative hazards showed that risk reductions associated with longer lactation were stronger among GDM (relative hazard range 0.14–0.56; P = 0.03) than non-GDM groups (relative hazard range 0.44–0.61; P = 0.03).

CONCLUSIONS

Longer duration of lactation was associated with lower incidence of the metabolic syndrome years after weaning among women with a history of GDM and without GDM, controlling for preconception measurements, BMI, and sociodemographic and lifestyle traits. Lactation may have persistent favorable effects on women's cardiometabolic health.
Insulin-Sensitizing Therapy Attenuates Type 2 Diabetes–Mediated Mammary Tumor Progression
Authors: Fierz Yvonne , Novosyadlyy Ruslan , Vijayakumar Archana , Yakar Shoshana , LeRoith Derek
Published: December 2009

OBJECTIVE

Type 2 diabetes increases breast cancer risk and mortality, and hyperinsulinemia has been identified as a major factor linking these two diseases. Thus, we hypothesized that pharmacological reduction of elevated insulin levels would attenuate type 2 diabetes–mediated mammary tumor progression.

RESEARCH DESIGN AND METHODS

We studied mammary tumor development in MKR+/+ mice, a nonobese, hyperinsulinemic mouse model of type 2 diabetes. MKR+/+ mice were either crossed with mice expressing the polyoma virus middle T oncogene specifically in the mammary gland or inoculated orthotopically with the mouse mammary tumor cell lines Met-1 and MCNeuA. MKR+/+ or control mice harboring tumors were treated with CL-316243, a specific β3-adrenergic receptor agonist, which sensitizes insulin action but has no direct effect on the mouse mammary epithelium or Met-1 and MCNeuA cells.

RESULTS

CL-316243 treatment significantly reduced the elevated insulin levels in MKR+/+ mice and, as a consequence, attenuated mammary tumor progression in the three tumor models tested. This effect was accompanied by reductions in phosphorylation of insulin and IGF-I receptors in transformed mammary tissue.

CONCLUSIONS

Insulin-sensitizing treatment is sufficient to abrogate type 2 diabetes–mediated mammary tumor progression. Therefore, early administration of insulin-sensitizing therapy may reduce breast cancer risk and mortality in patients with type 2 diabetes.
Effect of Bohm potential on a charged gas
Authors: Mostacci Domiziano , Molinari Vincenzo , Pizzio Francesco
Published: December 2009

Bohm’s interpretation of Quantum Mechanics leads to the derivation of a Quantum Kinetic Equation (QKE): in the present work, propagation of waves in charged quantum gases is investigated starting from this QKE. Dispersion relations are derived for fully and weakly degenerate fermions and bosons (for the latter above critical temperature) and the differences discussed. Use of a kinetic equation permits investigation of “Landau-type” damping: it is found that the presence of damping in fermion gases is dependent upon the degree of degeneracy, whereas it is always present in boson gases. In fully degenerate fermions a phenomenon appears that is akin to the “zero sound” propagation.
B and N-doped double walled carbon nanotube: a theoretical study
Authors: Mendes Lima Welber , Azevedo David , Guerini Silvete
Published: December 2009

The structural and electronic properties of boron and nitrogen atom substitutional doping in (8,0)@(13,0) (semiconductor@semiconductor) and (6,0)@(13,0) (metallic@semiconductor) double walled carbon nanotubes, were obtained by using the first-principle calculations based on the density functional theory. In this framework, the electronic density plays a central role and it was obtained from a self-consistent field form. When boron or nitrogen substitutes a carbon atom the structure remains practically the same with negligible deformation observed around defects in all configurations considered. The electronic band structure results indicate that the boron doped systems behave as a p-type impurity, however, the nitrogen doped systems behave as an n-type impurity. In all the systems investigated here, we found that, in the cases of semiconductor@semiconductor tubes, they were the easiest to incorporate a B atom in the outer-wall and an N atom in the inner-wall of the nanotube.
Nonextensive thermal sources of cosmic rays
Authors: Wilk Grzegorz , Włodarczyk Zbigniew
Published: December 2009

The energy spectrum of cosmic rays exhibits power-like behavior with a very characteristic ‘knee’ structure. We consider a possibility that such a spectrum could be generated by some specific nonstatistical temperature fluctuations in the source of cosmic rays with the ‘knee’ structure reflecting an abrupt change of the pattern of such fluctuations. This would result in a generalized nonextensive statistical model for the production of cosmic rays. The possible physical mechanisms leading to these effects are discussed together with the resulting chemical composition of the cosmic rays, which follows the experimentally observed abundance of nuclei.
Implementation of marginal quantities in management of cogeneration units operating in liberal market environment
Authors: Variny Miroslav , Mierka Otto
Published: December 2009

It is far more important how the cogeneration units are operated than whether they represent the latest technology progress or not. Therefore, for the management of cogeneration units it is a key issue to find optimal operating conditions bringing in the largest income. This may be achieved by combined marginal and overall performance criteria application. To prove this statement, two cogeneration units operating in the Slovak Republic, marked as A and B, were examined. Both of them use the liberal market environment and participate in provisioning ancillary services. Marginal profit values without and with ancillary services provisioning clearly indicate the most advantageous base load value, which is in both cases in the middle of the load regulation range. As shown, together with the total profit function, they are very suitable indicators of the optimal load location and a flexible tool for the market situation evaluation. Heat delivery capability of B to customers reaches its maximum at the middle of the load regulation range, again reinforcing the optimal part load operation. Being equipped with supplementary firing, the marginal steam production of B was found to be higher than 100 % which confirms that the rules for marginal quantities values are not as strict as those for overall and specific quantities.
Procedures of optical control dedicated for laser welding process of biological tissues
Authors: Zając A. , Podniesiński D. , Świderski J. , Kęcik D. , Kęcik M. , Kasprzak J.
Published: December 2009

In this contribution, an optical method of controlling the state of soft biological tissues in real time exposed to laser radiation is discussed. The method is based on the assumption that the change dynamics of the amplitude of the scattered diagnostic radiation (λ = 635 nm) is compatible with the change dynamics of the tissue inner structure exposed to the Nd:YAG laser radiation (λ = 1064 nm). In this method, the measurement of the tissue temperature is omitted. Exemplary results of the laboratory research on this method and an interpretation of the results are presented.
Recent advances on single photon sources based on single colloidal nanocrystals
Authors: Vittorio M. , Pisanello F. , Martiradonna L. , Qualtieri A. , Stomeo T. , Bramati A. , Cingolani R.
Published: December 2009

Single colloidal quantum dots (QDs) are increasingly exploited as triggered sources of single photons. This review reports on recent results on single photon sources (SPS) based on colloidal quantum dots, whose size, shape and optical properties can be finely tuned by wet chemistry approach. First, we address the optical properties of different colloidal nanocrystals, such as dots, rods and dot in rods and their use as single photon sources will be discussed. Then, we describe different techniques for isolation and positioning single QDs, a major issue for fabrication of single photon sources, and various approaches for the embedding single nanocrystals inside microcavities. The insertion of single colloidal QDs in quantum confined optical systems allows one to improve their overall optical properties and performances in terms of efficiency, directionality, life time, and polarization control. Finally, electrical pumping of colloidal nanocrystals light emitting devices and of NC-based single photon sources is reviewed.
Walking Skill Can Be Assessed in Older Adults: Validity of the Figure-of-8 Walk Test
Authors: Hess Rebecca J. , Brach Jennifer S. , Piva Sara R. , VanSwearingen Jessie M.
Published: December 2009

Background

The Figure-of-8 Walk Test (F8W) involves straight and curved paths and was designed to represent walking skill in everyday life.

Objective

The purposes of this study were to validate the measure in older adults with walking difficulties and to explore correlates of the curved-path walking measure not represented by a straight-path walking measure.

Design

Fifty-one community-dwelling older adults with mobility disability participated in 2 baseline visits as part of an intervention study.

Methods

The F8W time, steps, and smoothness and measures of gait (gait speed, modified Gait Abnormality Rating Scale [GARS-M]), physical function (Late Life Function and Disabilities Index [LLFDI], Survey of Activities and Fear of Falling in the Elderly [SAFFE], Gait Efficacy Scale [GES], Physical Performance Test [PPT], and fall history), and movement control and planning (gait variability, Trail Making Test B [Trails B]) were recorded in each test session. Bivariate correlations for the F8W with each variable were conducted to examine concurrent and construct validity. Adjusted linear regression analyses were performed to explore the variance in mobility explained by F8W independent of gait speed.

Results

Figure-of-8 Walk Test time correlated with gait (gait speed, r=−.570; GARS-M, r=.281), physical function (LLFDI function, r=−.469; SAFFE restriction subscale, r=.370; PPT, r=−.353), confidence in walking (GES, r=−.468), and movement control (step length coefficient of variation, r=.279; step width coefficient of variation, r=−.277; Trails B, r=.351). Figure-of-8 Walk Test steps correlated with step width variability (r=−.339) and was related to fear of falling (t=−2.50). All correlations were significant (P<.05).

Limitations

This pilot study had a small sample size, and further research is needed.

Conclusions

The F8W is a valid measure of walking skill among older adults with mobility disability and may provide information complementary to gait speed.