bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Numerical Simulation of Solar Cooker Type Box With Multi-Step Inner Reflector
Authors: Terre´s-Pen˜a H. , Quinto-Diez P.
Published: January 2009

It is shown a mathematical model of a solar box cooker with multi-step inner reflector and the numerical results for two applications has been analyzed. These applications are 1. Numerical simulation of operation of solar box cooker with multi-step inner reflector in Tanta, Egypt and 2. Numerical simulation of solar box cooker with multi-step inner reflector for 10 hours of operation. In the case 1, is analyzed a solar box cooker constructed and evaluated in Tanta, Egypt [1]. The experimental results that was obtained are compared with the numerical results that was obtained for the mathematical model. The case 2, is an evaluation of numerical results that was obtained for the operation of 10 hours for solar box cooker constructed in the Laboratorio de Ingenieri´a Te´rmica e Hidra´ulica Aplicada (LABINTHAP) in Me´xico City. [4] The solar box cooker is integrated by a covert that was made with double glass, this is use with two purposes, reduce the loss heat convection with outer and to generated the greenhouse effect with inner of cooker. In the inner of cooker there are a mirrors arrangement in inclined position (inner reflectors) placed in angles of 30°, 45° and 75°, these helped to reflex the solar rays in direction to the cook recipient. The recipient also received the solar rays in the upper part (lid). The mathematical model that was obtained from energetic analysis, is formed for five differential equations system no linear and the fourth Runge-Kutta method is used to resolve it. The numerical solution of the equations system is obtained with a computational software in C++. This work is a contribution to the application of numerical methods and computational for development of the solar energy used in thermal conversion equipments. The use of these techniques to solve the mathematical model is important to contribute in the evaluation and design of solar box cookers with multi-step inner reflector.
Thermal Performance of Unvented Attics in Hot-Dry Climates: Results From Building America
Authors: Hendron Robert , Farrar-Nagy Sara , Anderson Ren , Reeves Paul , Hancock Ed
Published: January 2009

As unvented attics have become a more common design feature implemented by Building America partners in hot-dry climates of the United States, more attention has been focused on how this approach affects heating and cooling energy consumption. By eliminating the ridge and eave vents that circulate outside air through the attic in most new houses and by moving the insulation from the attic floor to the underside of the roof, an unvented attic becomes a semiconditioned space, creating a more benign environment for space conditioning ducts. An energy trade-off is made, however, because the additional surface area (and perhaps reduced insulation thickness) increases the building loss coefficient. Other advantages and disadvantages, unrelated to energy, must also be considered. This paper addresses the energy-related effects of unvented attics in hot-dry climates based on field testing and analysis conducted by the National Renewable Energy Laboratory.
Uncertainty Estimates of Photovoltaic Module Performance Measurements
Authors: Atmaram Gobind H.
Published: January 2009

Commercially available photovoltaic (PV) modules and systems often fall short of meeting the performance ratings specified by the module manufacturers or system designers [1]. This has resulted in reduced performance and low system availability, some system failures, and generally, a lack of confidence by systems users. Hence, a need for an independent accredited laboratory to conduct the testing and certification of PV modules and systems has been indicated by the PV industry, electric utilities, and other system users and owners. To meet this industry and user need, the Florida Solar Energy Center (FSEC) has started a PV testing and certification program. The FSEC PV testing laboratory and certification program have been accredited by the American Association for Laboratory Accreditation (A2LA) and approved by the PowerMark Corporation (PMC, www.powermark.org ), which is the certification body of the PV industry in the United States. The FSEC program currently covers three areas: (i) PV module power rating certification, (ii) Stand-Alone PV system performance evaluation and certification, and (iii) Grid-Connected PV system design review and approval. The PV module power rating certification is central to these three areas of the FSEC program, as illustrated in Figure 1. The details of the FSEC PV testing laboratory accreditation and certification program are described in a previous paper [2].
Design and Testing of an Augmented Generator for Solar Fired Absorption Chillers
Authors: Bergquam James , Brezner Joseph , Jensen Andrew
Published: January 2009

This paper presents results from a project sponsored by the California Energy Commission that involved the design and testing of an augmented generator for a solar fired, double effect absorption chiller. Solar powered absorption chillers use water heated by an array of solar collectors to boil a solution of lithium bromide and water. The energy transfer process between pressurized water heated by the solar collectors and the LiBr/H2O solution is the focus of this study. A method of augmenting the heat transfer in the generator was developed, bench tested and implemented in an operating 70kW solar HVAC system. The augmented design involved installing twisted stainless steel inserts in the tubes where the LiBr/H2O solution boils and refrigerant vapor is generated. The inserts increased the overall heat transfer coefficient between the heat medium in the shell side of the generator and the LiBr/H2O solution in the tubes. A solar-fired, double effect absorption chiller requires the collector array and storage tank to operate at temperatures in excess of 150°C. At these temperatures, the heating water must be at a pressure of about 700kPa to prevent it from boiling. This combination of high temperature and high pressure requires that the collectors, storage tanks, pumps, valves and piping be designed according to pressure vessel codes. This increases the initial cost of the system and also requires significant maintenance. The main objective of this work is to develop a method of lowering the requirements for a 150°C heating medium. The ultimate goal is to operate at about 120°C while maintaining the Coefficient of Performance and cooling capacity of the absorption chiller. The results presented in this paper show that the generator with twisted inserts can operate with an average log mean temperature difference of 10°C. The average COP of the chiller is about 1.0 and the chiller provided all of the cooling required by a 743 m2 building. Without the twisted inserts, the generator operated with a temperature difference of 22 to 28°C. The inserts provide significant reduction in the operating temperature of the solar collectors and do not adversely affect the performance of the double effect absorption chiller.
Bituminous Pavement Constructed With Municipal Solid Waste Combustor Ash: Construction, Performance, and Economic Issues
Authors: Lucido Samuel P. , Wilson Willard
Published: January 2009

The Polk County Solid Waste Department, located in Polk County Minnesota, participates in a complete integrated solid waste management program that includes four other counties in northwest Minnesota. One component of the integrated solid waste management program includes the operation of a municipal waste combustor (MWC) that combusts approximately 65 tons per day of processed solid waste. The starved air design of the combustor causes low turbulence in the primary burning chamber minimizing particulate carryover through the system. This results in generation of approximately 12 tons per day of combined ash comprised of 98 to 99 percent bottom ash and 1 to 2 percent fly ash, by weight.
Collier County, Florida: Consideration of Gasification as a Long-Term Waste Management Solution
Authors: Schwarz Stephen C. , Dietch Daniel E.
Published: January 2009

Collier County, Florida (“County”) is in the midst of developing an integrated waste management program. Unlike many counties, Collier County owns a landfill with sufficient long-term landfill capacity to last another 15 years. However, due to the Board of County Commissioner’s (“Board”) desire to have a 50-year solution for solid waste, the County has set upon a course to divert waste from the landfill to the maximum extent possible. In doing so, the County solicited long-term waste management solutions from private companies capable of processing the majority of the municipal solid waste generated in the County. Over the past two years, the County has considered several of these alternatives ranging from MSW composting to mass-burn waste-to-energy; however, based on an evaluation of a wide range of impacts, gasification was selected as the preferred alternative. With this focus, the County issued a Request for Proposal (“RFP”) in November 2001 for a design, build, own, operate, and finance gasification project. The County received three proposals in April 2002 in response to the RFP. To date, the County has completed the proposal evaluation process and has ranked the top two responsive firms: Interstate Waste Technologies (“IWT”) and Brightstar Environmental (Florida), LLC (“Brightstar”) based on experience, technical approach, business arrangement, and cost. If implemented, this project will be the only commercial gasification project operating in the United States. This paper will provide insight into various stages of the project, from development through to the current status of the project, as well as the strategic policy, financial, and technical considerations that make this opportunity a good fit for the County. An emphasis will also be placed on comparing and contrasting the benefits and drawbacks of each technology, such as processing methodology, cost, redundancy, and scalability.
Scaling of Solutions for the Lateral Buckling of Elastic-Plastic Pipelines
Authors: Peek Ralf , Yun Heedo
Published: January 2009

Analytical solutions for the lateral buckling of pipelines exist for the case when the pipe material remains in the linearly elastic range. However for truly high temperatures and/or heavier flowlines, plastic deformation cannot be excluded. One then has to resort to finite element analyses, as no analytical solutions are available. This paper does not provide such an analytical solution, but it does show that if the finite element solution has been calculated once, then that solution can be scaled so that it applies for any other values of the design parameters. Thus the finite element solution need only be calculated once and for all. Thereafter, other solutions can be calculated by scaling the finite element solution using simple analytical formulae. The only significant limitation is that the shape of the moment-curvature relation must not change. I.e. the moment-curvature relation for the problem to be solved must be a scaled version of the moment-curvature relation for the reference problem, where different scale factors may be applied to the moment and curvature. This paper goes beyond standard dimensional analysis (as justified by the Bucklingham Π theorem), to establish a stronger scalability result, and uses it to develop simple formulae for the lateral buckling of any pipeline made of elastic-plastic material. The paper includes the derivation of the scaling result, the application procedure, the reference solution for an elastic-perfectly plastic pipe, and an example to illustrate how this reference solution can be used to calculate the lateral buckling response for any elastic-perfectly plastic pipe.
Dynamic Analysis of a Monopod Platform Using Constrained NewWave
Authors: Pinna Rodney , Cassidy Mark
Published: January 2009

This paper considers the dynamic response of an example minimum structure, in this case a monopod, for conditions typical of the North West Shelf of Australia. The dynamic response is assessed using both conventional 3 hour storm simulation techniques, and the Constrained NewWave methodology. The results from both analyses are found to be comparable in terms of the DAF value that was found. The structure was found to have significant dynamic response, particularly as the wave return period increased.
Vortex-Induced Vibration of Catenary Moored Cylindrical Structures
Authors: Stappenbelt Brad , Thiagarajan Krish
Published: January 2009

Mooring systems utilised for floating structures typically introduce non-linear load-excursion behaviour. This non-linear compliance and the accompanying amplitude dependent natural frequency, influences the Vortex-Induced Vibration (VIV) response of the structure. The application of linear compliance VIV modelling and experimental data has been demonstrated to produce significant uncertainties regarding VIV onset and response prediction of catenary moored cylindrical structures (Bjarke et al. 2003; Dijk et al. 2003). The vortex-induced vibration issues associated with catenary moored cylindrical structures were investigated through non-linearly compliant elastically mounted rigid cylinder experiments. In particular, third order polynomial, hard spring stiffness, (typical of catenary moorings) was considered. The effect on transverse VIV lock-in and vibration amplitudes was examined using a single degree of freedom experimental rig. The experimental rig consisted of a moderately damped, elastically mounted rigid cylinder, restricted in all but the cross-flow direction through use of linear slide mechanism. The linear and cubic compliance components were independently varied over the non-linear compliance ratio of 0 to 0.3. All experimentation was conducted within the stable sub-critical Reynolds number range. The experimental data was compared to numerical results produced by the VIV modelling software package VisFlo. The program utilises a vortex-in-cell discrete vortex numerical method that was modified to allow the inclusion of varying degrees of structural non-linearity.
Analyses of a Large Diameter Steel Lazy Wave Riser for Ultra Deepwater in Campos Basin
Authors: Franciss Ricardo , Ribeiro Elton
Published: January 2009

Petrobras is going deeper and some fields are feasible only if the production platforms are installed in ultra deep waters, close to the wells. In one case in Campos Basin, for example, the platform will be installed at 1255 m water depth and the solution to allow the production is based on the evolution of flexible lines for high pressure and high loads. For the oil export line, however, a steel rigid line was chosen, due to the large diameter. Some analyses were performed in order to make it feasible the installation of an 18-inch SCR export oil line. Due to fatigue loads, the free hanging catenary configuration did not match with API RP 2RD recommendations, so Petrobras decided to change the original shape to Lazy Wave in order to reduce the top loads and increase the fatigue life. But, some configurations are not feasible to install. High angles close to the installation vessel or high stresses close to the flotation segments are some problems that must be solved. This article will present the steps made to reach a configuration that will make feasible the installation of this riser, in parallel to the static and dynamic analysis, to maintain the stresses in an allowable level, in accordance with API RP 2RD.
Assessment of Structural Reliability of Ships Under Combined Loading Including Extreme Diurnal Temperature Effects
Authors: Moatsos Ioannis , Das Purnendu K.
Published: January 2009

Research communities of various engineering and physical science fields have in the last year placed a lot of emphasis on modelling the ways climate change affects different engineering systems and therefore influences the methods by which these systems are designed. With a progressive change of our global climate to warmer and more variable conditions worldwide the effects of extreme weather changes are becoming now, more than ever, evident to our everyday lives and affect our safety. It is this effect of climate change that engineers now face the task of incorporating in their design of engineering systems, especially in the ship and offshore-related fields. In such cases of mathematical modelling and analysis variations of more than one variable that is climate dependent can significantly affect the design. The fact that ship structures do encounter temperature conditions that induce thermal stresses and deformation of practical importance has been recognized for some time. The need to develop efficient techniques of modelling extreme environmental phenomena is hence now more relevant than ever in the history of this type of research. A large amount of research exists in the area of extreme wave phenomena and their effects but in terms of extreme temperature and the effect of diurnal temperature changes research published has been very limited. This paper places emphasis on the modelling of loads for use in reliability analysis. Load combination methodology is used for the combination of wave bending, still water, slamming and thermal loads using various stochastic methods for load combination. A case study of an FPSO/Tanker vessel is analysed and diurnal temperature cycles, on structures already in operation in the North Sea/West of Shetland area, are modelled using these load combination techniques. Load combination factors are then introduced for calculating the total hull girder bending moment. Corrosion effects on the structure are modelled using a simple mathematical model derived from actual vessel measurements, statistical analysis and published research. Reliability analysis using a FORM-SORM component approach provides Partial Safety Factors and probabilities of failure.
Instability of Tensile Armour Layers of Flexible Pipes Under External Pressure
Authors: Bectarte Fabrice , Coutarel Alain
Published: January 2009

During their installation and some phases of their service life, the armour wires of flexible pipes may be operated under high compressive forces. Under this kind of loading, there is a potential risk of damage on the tensile armour layers of those pipes along two main mechanisms: - Radial instability, usually referred to as “Bird caging”. - Lateral instability, usually referred to as “lateral buckling” when cyclic bending is applied to the pipe. This paper focuses on Lateral instability issues. It discusses a methodology for the prediction of lateral buckling based on extensive testing both onshore and offshore Brazil. In particular, the major influence of the armour annulus state (Dry or flooded) on the lateral buckling mechanism will be discussed. This approach of tensile armour instability has been recently confirmed by the successful testing of a 7” flexible riser in 2000 m water depth and of a 9” flexible riser in 1800 m water depth.
Coupled Mooring Analysis for a Deep Water CALM Buoy
Authors: Cozijn J. L. , Bunnik T. H. J.
Published: January 2009

The effect of the mooring loads on floator motions can be significant for small water plane are floaters like CALM buoys. Not only does the mooring system contribute to the static restoring force components, but the dynamic behaviour of the mooring lines also affects the inertia and damping of the moored CALM buoy. The results from model tests with a moored CALM buoy were compared with the results from two series of time-domain computer simulations. First, fully dynamic coupled simulations were carried out, in which the interaction between the floater motions and the dynamic mooring line loads was modelled for all 6 modes of motion. Second, quasi-static simulations were carried out, in which only the (non-linear) static restoring force characteristics of the mooring system were taken into account. The comparison of results from the simulations and the model tests clearly indicates that the fully dynamic coupled simulations show a much better correspondence with the model test results than the quasi-static simulations. It is concluded that for the simulation of the behavior of a moored CALM buoy in waves a fully dynamic coupled mooring analysis is essential.
Design and Construction of Solar Thermal Tile Systems for Stand-By Heating of Emergency Diesel Generators
Authors: Archibald John P.
Published: January 2009

Emergency diesel generators in outdoor enclosures use large amounts of electric resistance heat to keep the engines warm all year. The heat is delivered to the jacket water of the engine by means of an electric resistance cartridge heater. For mid sized generators (150 KW – 1,000 KW) the annual electric use to deliver 130 degree F water can be 10,000 to 30,000 kwhr in a climate zone with 4,000 heating degree days (65 F base). An alternative to electric heating of the jacket water, is to solar heat the enclosure with 110 F air. This reduces the heat loss from the engine and therefore reduces the demand on the electric resistance heater. The paper describes the opportunity for solar air heating of emergency generators and the design and construction of two ground mounted systems and one solar heating building at the US Geological Survey in Reston, VA.
Grain Flow for Rough Surfaces Considering Elastic/Inelastic Grain Collision
Authors: Jeng Yeau-Ren , Tsai Hung-Jung
Published: January 2009

Previous work by this group on an average lubrication equation for grain flow with roughness effects is extended to include grain-grain collision elasticity ranging from perfectly elastic to perfectly inelastic. The average lubrication equation is based on Haff’s grain flow theory, with flow factors from Patir and Cheng and Tripp’s use of perturbation. The derived flow factors are obtained as functions of rough surface characteristics, grain size and collision pattern. As collision energy loss approaches zero, the inelastic results approach those for perfectly elastic grain collision. The mathematical formulae for flow factors, grain/grain collision elasticity, grain size and roughness are presented, discussed. Predictions for the elastic and inelastic cases are graphically demonstrated and compared.
In-Situ Quantitative Integrated Tribo-SPM Nano-Micro-Metrology
Authors: Gitis Norm , Daugela Antanas , Sikder Arun , Vinogradov Michael , Meyman Alex
Published: January 2009

A novel quantitative nano/micro-tribometer with integrated SPM and optical microscope imaging has been developed to characterize numerous physical and mechanical properties of liquid and solid thin films and coatings, with in-situ monitoring their changes during micro and nano indentation, scratching, reciprocating, rotating and other tribology tests. Both the materials properties and surface topography can be assessed periodically during the tests.
Quinolone Resistance in
Neisseria gonorrhoeae
: Rapid Genotyping of Quinolone Resistance-Determining Regions in
gyrA
and
parC
Genes by Melting Curve Analysis Predicts Susceptibility
Authors: Vernel-Pauillac Frédérique , Hogan Tiffany R. , Tapsall John W. , Goarant Cyrille
Published: January 2009

We report a duplex real-time PCR assay for the simultaneous screening of mutations involved in fluoroquinolone resistance within
gyrA
and
parC
quninolone resistance-determining regions (QRDRs) in
Neisseria gonorrhoeae
. Our assay clearly detects all mutated QRDRs and allows the identification of common genotypes, whether the QRDRs contain single or double mutations, providing valuable epidemiological tools. When this method is used in conjunction with similar assays and in vitro analyses, essential antibiotic resistance surveillance can be performed for public health purposes.
Contribution of
vraSR
and
graSR
Point Mutations to Vancomycin Resistance in Vancomycin-Intermediate
Staphylococcus aureus
Authors: Cui Longzhu , Neoh Hui-min , Shoji Mitsutaka , Hiramatsu Keiichi
Published: January 2009

We describe here the genetic analysis of a vancomycin-susceptible
Staphylococcus aureus
(VSSA) strain, Mu50Ω, a strain related to vancomycin-intermediate
S. aureus
(VISA) strain Mu50. Using a combination of Mu50Ω whole-genome sequencing and genome engineering, we observed a stepwise evolution of vancomycin resistance from VSSA to VISA after the mutated
vraS
and
graR
genes of Mu50 were engineered into Mu50Ω.
Involvement of
Shewanella oneidensis
MR-1 LuxS in Biofilm Development and Sulfur Metabolism
Authors: Learman Deric R. , Yi Haakrho , Brown Steven D. , Martin Stanton L. , Geesey Gill G. , Stevens Ann M. , Hochella Michael F.
Published: January 2009

The role of LuxS in
Shewanella oneidensis
MR-1 has been examined by transcriptomic profiling, biochemical, and physiological experiments. The results indicate that a mutation in
luxS
alters biofilm development, not by altering quorum-sensing abilities but by disrupting the activated methyl cycle (AMC). The
S. oneidensis
wild type can produce a luminescence response in the AI-2 reporter strain
Vibrio harveyi
MM32. This luminescence response is abolished upon the deletion of
luxS
. The deletion of
luxS
also alters biofilm formations in static and flowthrough conditions. Genetic complementation restores the mutant biofilm defect, but the addition of synthetic AI-2 has no effect. These results suggest that AI-2 is not used as a quorum-sensing signal to regulate biofilm development in
S. oneidensis
. Growth on various sulfur sources was examined because of the involvement of LuxS in the AMC. A mutation in
luxS
produced a reduced ability to grow with methionine as the sole sulfur source. Methionine is a key metabolite used in the AMC to produce a methyl source in the cell and to recycle homocysteine. These data suggest that LuxS is important to metabolizing methionine and the AMC in
S. oneidensis
.
CONGRUENCES AND EXPONENTIAL SUMS WITH THE SUM OF ALIQUOT DIVISORS FUNCTION
Authors: BALASURIYA SANKA , BANKS WILLIAM D. , SHPARLINSKI IGOR E.
Published: January 2009

We give bounds on the number of integers 1 ≤ n ≤ N such that p | s(n), where p is a prime and s(n) is the sum of aliquot divisors function given by s(n) = σ(n) - n, where σ(n) is the sum of divisors function. Using this result, we obtain nontrivial bounds in certain ranges for rational exponential sums of the form [Formula: see text]
POLYNOMIALS FOR HYPER-KLOOSTERMAN SUMS
Authors: GURAK S.
Published: January 2009

Fix an integer m > 1, and let [Formula: see text] denote the group of reduced residues modulo m and set ζm = exp (2 πi/m). Let [Formula: see text] denote the multiplicative inverse of x modulo m. The n-dimensional Kloosterman sums are defined by [Formula: see text] and satisfy the polynomial [Formula: see text] where the product is taken over a reduced system of residues modulo m. Here we give a natural factorization of fm(x); namely, [Formula: see text] where σ runs through the n + 1-st power classes modulo m. Questions concerning the determination of the factors [Formula: see text] (or at least their beginning coefficients), their reducibility over the rational field Q and duplications among the factors are studied. The treatment generalizes results of the author in the classical case n = 1, and relies heavily on the recent explicit evaluation of hyper-Kloosterman sums for prime powers.
Congenic strains provide evidence that four mapped loci in chromosomes 2, 4, and 16 influence hypertension in the SHR
Authors: Aneas Ivy , Rodrigues Mariliza V. , Pauletti Bianca A. , Silva Gustavo J. J. , Carmona Renata , Cardoso Leandro , Kwitek Anne E. , Jacob Howard J. , Soler Julia M. P. , Krieger Jose E.
Published: January 2009

To dissect the genetic architecture controlling blood pressure (BP) regulation in the spontaneously hypertensive rat (SHR) we derived congenic rat strains for four previously mapped BP quantitative trait loci (QTLs) in chromosomes 2, 4, and 16. Target chromosomal regions from the Brown Norway rat (BN) averaging 13–29 cM were introgressed by marker-assisted breeding onto the SHR genome in 12 or 13 generations. Under normal salt intake, QTLs on chromosomes 2a, 2c, and 4 were associated with significant changes in systolic BP (13, 20, and 15 mmHg, respectively), whereas the QTL on chromosome 16 had no measurable effect. On high salt intake (1% NaCl in drinking water for 2 wk), the chromosome 16 QTL had a marked impact on SBP, as did the QTLs on chromosome 2a and 2c (18, 17, and 19 mmHg, respectively), but not the QTL on chromosome 4. Thus these four QTLs affected BP phenotypes differently: 1) in the presence of high salt intake (chromosome 16), 2) only associated with normal salt intake (chromosome 4), and 3) regardless of salt intake (chromosome 2c and 2a). Moreover, salt sensitivity was abrogated in congenics SHR.BN2a and SHR.BN16. Finally, we provide evidence for the influence of genetic background on the expression of the mapped QTLs individually or as a group. Collectively, these data reveal previously unsuspected nuances of the physiological roles of each of the four mapped BP QTLs in the SHR under basal and/or salt loading conditions unforeseen by the analysis of the F2 cross.
Interpreting Neonatal Lethal Phenotypes in Mouse Mutants: Insights Into Gene Function and Human Diseases
Authors: Turgeon Benjamin , Meloche Sylvain
Published: January 2009

The mouse represents the model of choice to study the biological function of mammalian genes through mutation of its genome. However, the biggest challenge of mouse geneticists remains the phenotypic analysis of mouse mutants. A survey of mouse mutant databases reveals a surprisingly high number of gene mutations leading to neonatal death. These genetically modified mouse mutants have been instrumental in elucidating gene function and have become important models of congenital human diseases. The main complication when phenotyping mutant mice dying during the neonatal period is the large spectrum of physiological systems whose defects can challenge neonatal survival. Here, we present a comprehensive review of gene mutations leading to neonatal lethality and discuss the impact of these mutations on the major physiological processes critical to mouse newborn survival: parturition, breathing, suckling, and homeostasis. Selected examples of mouse mutants are highlighted to illustrate how the precise identification of the timing and cause of death associated with these physiological processes allows for a more profound understanding of the underlying cellular and molecular defects. This review provides a guide for the analysis of neonatal lethal phenotypes in mutant mice that will be helpful for dissecting out the function of specific genes during mouse development.
On the Existence of Solutions of a Nonlocal Elliptic Equation with a p‐Kirchhoff‐Type Term
Authors: Corrêa Francisco Julio S. A. , Nascimento Rúbia G.
Published: January 2009

Questions on the existence of positive
solutions for the following class of elliptic problems are studied: , in Ω, u = 0, on ∂Ω, where Ω ⊂ ℝN is a bounded smooth domain, and M : ℝ+ → ℝ,   ℝ+ = [0, ∞) are given functions.
Fast Dynamics in the Optical Storage with Langmuir–Blodgett Films of a Diazocrown Ether Molecule
Authors: Shimizu Flávio M. , Ferreira Marystela , Constantino Carlos J. L. , Skwierawska Anna S. , Biernat Jan F. , Giacometti José A.
Published: January 2009

Azobenzene-containing molecules have been studied for a number of applications exploiting the efficient trans-cis-trans photoisomerization cycles, which lead to molecular alignment and even micrometer-scale mass transport. One of the limitations of these materials, though, is
the slow dynamics of the alignment process that requires significant molecular rearrangement. In this paper, we report on Langmuir–Blodgett (LB) films of a derivative of azocrown ether, referred to as 29-membered diazocrown ether, specially synthesized for the photoisomerization to involve
only distortion of the shape of the crown. As a result, the dynamics of the writing process was extremely fast, with maximum birefringence being reached within less than 1 s, to be contrasted with tens or even hundreds of seconds for other azobenzene materials. A disadvantage is this strategy,
however, is that the resulting birefringence was low, of the order of 10−3, because the closely packed arrangement prevented the whole diazocrown molecule to be fully reoriented. From a comparison with results obtained in guest-host, cast films where the 29-membered diazocrown
ether was incorporated into a polystyrene matrix, we confirmed that both fast dynamics and small birefringence features are due to a combination of effects from the nanostructured nature of the LB films and the molecular structure of the specially-designed diazocrown ether. Significantly,
the fast dynamics opens the way for various applications, as in command surfaces for liquid crystal devices.
An internal ribosome entry site element directs the synthesis of the 80 kDa isoforms of protein 4.1R
Authors: Lospitao Eva , Pérez-Ferreiro Carmen M , Gosálbez Altea , Alonso Miguel A , Correas Isabel
Published: January 2009

Background

In red blood cells, protein 4.1 (4.1R) is an 80 kDa protein that stabilizes the spectrin-actin network and anchors it to the plasma membrane through its FERM domain. While the expression pattern of 4.1R in mature red cells is relatively simple, a rather complex array of 4.1R protein isoforms varying in N-terminal extensions, internal sequences and subcellular locations has been identified in nucleated cells. Among these, 135 kDa and 80 kDa isoforms have different N-terminal extensions and are expressed either from AUG1- or AUG2-containing mRNAs, respectively. These two types of mRNAs, varying solely by presence/absence of 17 nucleotides (nt) which contain the AUG1 codon, are produced by alternative splicing of the 4.1R pre-mRNA. It is unknown whether the 699 nt region comprised between AUG1 and AUG2, kept as a 5' untranslated region in AUG2-containing mRNAs, plays a role on 4.1R mRNA translation.

Results

By analyzing the in vitro expression of a panel of naturally occurring 4.1R cDNAs, we observed that all AUG1/AUG2-containing cDNAs gave rise to both long, 135 kDa, and short, 80 kDa, 4.1R isoforms. More importantly, similar results were also observed in cells transfected with this set of 4.1R cDNAs. Mutational studies indicated that the short isoforms were not proteolytic products of the long isoforms but products synthesized from AUG2. The presence of a cryptic promoter in the 4.1R cDNA sequence was also discounted. When a 583 nt sequence comprised between AUG1 and AUG2 was introduced into bicistronic vectors it directed protein expression from the second cistron. This was also the case when ribosome scanning was abolished by introduction of a stable hairpin at the 5' region of the first cistron. Deletion analysis of the 583 nt sequence indicated that nucleotides 170 to 368 are essential for expression of the second cistron. The polypyrimidine tract-binding protein bound to the 583 nt active sequence but not to an inactive 3'-fragment of 149 nucleotides.

Conclusion

Our study is the first demonstration of an internal ribosome entry site as a mechanism ensuring the production of 80 kDa isoforms of protein 4.1R. This mechanism might also account for the generation of 60 kDa isoforms of 4.1R from a downstream AUG3. Our results reveal an additional level of control to 4.1R gene expression pathways and will contribute to the understanding of the biology of proteins 4.1R and their homologues, comprising an ample family of proteins involved in cytoskeletal organization.
Phylogenetic studies reveal existence of multiple lineages of a single genotype of DENV-1 (genotype III) in India during 1956–2007
Authors: Kukreti Himani , Dash Paban Kumar , Parida Manmohan , Chaudhary Artee , Saxena Parag , Rautela RS , Mittal Veena , Chhabra Mala , Bhattacharya D , Lal Shiv , Rao PV Lakshmana , Rai Arvind
Published: January 2009

Background

Dengue virus type 1 (DENV-1) have been mostly circulating silently with dominant serotypes DENV-2 and DENV-3 in India. However recent times have marked an increase in DENV-1 circulation in yearly outbreaks. Many studies have not been carried out on this virus type, leaving a lacunae pertaining to the circulating genotypes, since its earliest report in India. In the present study, we sequenced CprM gene junction of 13 DENV-1 isolated from Delhi and Gwalior (North India) between 2001–2007 and one 1956 Vellore isolate as reference. For comparison, we retrieved 11 other Indian and 70 global reference sequences from NCBI database, making sure that Indian and global isolates from all decades are available for comparative analysis.

Results

The region was found to be AT rich with no insertion or deletion. Majority of the nucleotide substitutions were silent, except 3 non-conservative amino acid changes (I → T, A → T and L → S at amino acid positions 59,114 and 155 respectively) in the Indian DENV-1 sequences, sequenced in this study. Except two 1997–98 Delhi isolates, which group in genotype I; all other Indian isolates group in genotype III. All Indian genotype III DENV-1 exhibited diversity among them, giving rise to at least 4 distinct lineages (India 1–4) showing proximity to isolates from diverse geographic locations.

Conclusion

The extensive phylogenetic analysis revealed consistent existence of multiple lineages of DENV-1 genotype III during the last 5 decades in India.
Fast Gene Ontology based clustering for microarray experiments
Authors: Ovaska Kristian , Laakso Marko , Hautaniemi Sampsa
Published: January 2009

Background

Analysis of a microarray experiment often results in a list of hundreds of disease-associated genes. In order to suggest common biological processes and functions for these genes, Gene Ontology annotations with statistical testing are widely used. However, these analyses can produce a very large number of significantly altered biological processes. Thus, it is often challenging to interpret GO results and identify novel testable biological hypotheses.

Results

We present fast software for advanced gene annotation using semantic similarity for Gene Ontology terms combined with clustering and heat map visualisation. The methodology allows rapid identification of genes sharing the same Gene Ontology cluster.

Conclusion

Our R based semantic similarity open-source package has a speed advantage of over 2000-fold compared to existing implementations. From the resulting hierarchical clustering dendrogram genes sharing a GO term can be identified, and their differences in the gene expression patterns can be seen from the heat map. These methods facilitate advanced annotation of genes resulting from data analysis.
Argon laser peripheral iridoplasty for plateau iris associated with iridociliary cysts: a case report
Authors: Ang Ghee Soon , Bochmann Frank , Azuara-Blanco Augusto
Published: January 2009

Introduction

Plateau iris is recognised as an important cause of primary angle closure glaucoma. The management of this condition generally comprises laser peripheral iridotomy and iridoplasty, to remove any component of relative pupillary block and to widen the iridotrabecular drainage angle respectively. However, plateau iris may be associated with multiple iris cysts at the iridociliary junction, which then presents diagnostic and management problems.

Case presentation

We present a fifty-three year old Caucasian gentleman with plateau iris associated with peripheral iris cysts, in which the iridotrabecular angle did not widen despite having had both laser peripheral iridotomy and iridoplasty. The patient has remained asymptomatic over 12 months, and is under close follow-up to monitor for signs of glaucoma.

Conclusion

Plateau iris with iridociliary cysts can be difficult to diagnose and manage. Ultrasound biomicroscopy should be performed on patients with appositional iridotrabecular angle closure on gonioscopy, especially if the angle closure is not relieved with either laser peripheral iridotomy or iridoplasty. Question marks can be raised as to the benefit of laser iridotomy when plateau iris without pupillary block has already been conclusively diagnosed on ultrasound biomicroscopy.
Abrasive wear of polymer/steel gear drives
Authors: Kalácska Gábor
Published: January 2009

Research was performed on the friction, wear and efficiency of plastic gears made of modern engineering polymers and their composites both in a clean environment (adhesive sliding surfaces) and in an environment contaminated with solid particles and dust (abrasive), with no lubrication at all. The purpose is to give a general view about the results of abrasive wear tests including seven soil types as abrasive media. At the first stage of the research silicious sand was applied between the meshing gears and the wear of plastic and steel gears was evaluated and analyzed from the point of different material properties (elongation at break, hardness, yield stress, modulus of elasticity) and its combinations. The different correlations between the experienced wear and material features are also introduced. At the second stage of the project the abrasive sand was replaced with different physical soil types. The abrasive wear of gears is plotted in the function of soil types. The results highlight on the considerable role of physical soil types on abrasive wear resistance and the conclusions contain the detailed wear resistance. The results offer a new tribology database for the operation and maintenance of agricultural machines with the opportunity of a better material selection according to the dominant soil type. This can finally result longer lifetime and higher reliability of wearing plastic/steel parts.
Effect of UV radiation and temperature on rheological features of multi-layer agricultural packaging foils
Authors: Csatár Attila , Fenyvesi László
Published: January 2009

The objective of the work reported here was to determine the influence of UV radiation and environmental temperature on the strength and rheological characteristics of multilayer agricultural packaging foils. The transmission properties of the experimental foils were tested in 286–363.5 nm range. The analysis of transmission properties of the foils showed that the maximum transmission was 10 % and 45 % with the experimental violet foils having 20 % and 5 % UV inhibitor in them, respectively. However, the transmission was higher than 80 % with the white foils of 5 % and 20 % inhibitor.The effect of the temperature on the tensile stress of commercial foils was investigated gated in the −20 ≤
T
≤ 50 °C temperature range. The measured relaxation curve was found to have a close correlation both for −10°C and 45°C with the calculated results. The highest reduced strength decreased as the function of the temperature according to the σ= −0,1861
T
+19,107 [MPa] equation. Therefore, the probability of the break of the foils in cold weather is definitely higher than under warm weather conditions.
Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar
Authors: Granlund Nils , Lundberg Angela , Feiccabrino James , Gustafsson David
Published: January 2009

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.
Recent advances in structure and reactivity of dissolved organic matter in natural waters
Authors: Cooper William J. , Song Weihua , Gonsior Michael , Kalnina Daina , Peake Barrie M. , Mezyk Stephen P.
Published: January 2009

The goal of our research is to better understand the structure and reactivity of natural dissolved organic matter (DOM) in aquatic environments. A more detailed knowledge of these DOM characteristics would lead to a better understanding of carbon cycling in natural waters and processes associated with water treatment using free radical chemistry. Our specific interest in DOM in natural waters is several-fold: 1) the photochemical formation of reactive oxygen species, 2) photobleaching of the DOM in coastal oceans, and 3) using chromophoric DOM (CDOM) as a tracer of water masses and in carbon cycling. Our interest in water treatment is that DOM is the major sink of hydroxyl radicals employed in advanced oxidation processes for the destruction of pollutants and thus adversely affects the efficiency of the process. We are using the techniques of radiation chemistry to explore the fundamental free radical and redox chemistry of DOM. We have initiated a study of the free radical reactions of DOM using isolated fractions of Suwannee River fulvic and humic acids and isolates from various anthropogenic sources. We are also investigating the use of model compounds in an attempt to understand the free radical transients formed from DOM either as a result of free radical reactions or photochemical reactions.
Advances in the characterization of the polarity of DOM under ambient water quality conditions using the polarity rapid assessment method
Authors: Philibert Marc , Bush Steve , Rosario-Ortiz Fernando L. , (Mel) Suffet I. H.
Published: January 2009

Dissolved organic matter (DOM) is a mixture of compounds that are found ubiquitously in natural waters. The characterization of DOM is important in order to understand its effect on environmental processes and during treatment systems. Of all the properties usually measured with relation to DOM, the polarity is of critical importance since it will directly influence different processes. Recently, a new method has been developed for the characterization of DOM under ambient conditions, called the Polar Rapid Assessment Method (PRAM). The PRAM allows characterization and temporal and spatial comparisons under environmentally relevant conditions of pH and ionic strength. This study first modifies the PRAM method to 3 probes for high sample throughput by using a subset of the SPE sorbents to interpret DOM polarity by DOC and UV detection. Then the modified PRAM is compared to the XAD resin polarity method and finds a similarity in hydrophobic assessment but different results for the hydrophilic DOM. This study then evaluates the use of PRAM as a tool to evaluate water treatment processes and the character of size fractions of DOM. The PRAM is shown to be a very useful tool to evaluate and thus optimize treatment efficiency and removal of DOM.
Effects of Carbamide Peroxide on the Staining Susceptibility of Tooth-colored Restorative Materials
Authors: Yu H. , Pan X. , Lin Y. , Li Q. , Hussain M. , Wang Y.
Published: January 2009

Clinical Relevance

The staining susceptibility of esthetic restorative materials is significantly affected by the use of 15% carbamide peroxide. The effects of bleaching on the surface morphology and color of restorative materials are material dependent.
The Use of a Microscope for Restorative Treatment Decision-making on Occlusal Surfaces
Authors: Akarslan Z. Z. , Erten H.
Published: January 2009

Clinical Relevance

The use of an operating microscope at 16× magnification did not aid in the restorative treatment decision-making on posterior teeth.