bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonsteady Supercritical Discharge Through an Orifice
Authors: Rudinger George
Published: November 2011

Previous studies of shock reflection from open-ended duct configurations indicate that a steady discharge is not instantaneously formed and that the effects of this lag may occasionally be important. A theory is available which satisfactorily describes the lag effects in subcritical flow, but its validity for supercritical flow has not previously been verified. Shock-tube experiments are therefore carried out to study the lag effects in supercritical flow from a sharp-edged orifice. The incident shock wave either modifies an initial supercritical discharge, or establishes such a discharge with the gas initially being at rest. Schlieren photographs show a violent transition of the flow downstream of the orifice that lasts several milliseconds. Pressure records taken inside the duct indicate a small, but distinct, pressure rise that also lasts for several milliseconds following the passage of the reflected shock wave. It is shown that this apparent agreement of the transition times is accidental. A method is described to evaluate the effect of boundary-layer growth on the pressure behind the reflected shock wave, and the results indicate that the entire observed pressure rise is accounted for by this effect. Consequently, flow adjustment in the orifice may be considered as instantaneous for all practical purposes.
Hydroelastic Vibrations of Flat Plates Related to Trailing Edge Geometry
Authors: Toebes G. H. , Eagleson P. S.
Published: November 2011

Vortex-induced vibrations of thin flat plates are studied as a function of trailing edge geometry. In an effort to extend the analysis to a more comprehensive treatment than that provided by the common vortex model, the vibrations are considered as hydroelastic phenomena. An equation of motion is formulated. From a qualitative analysis of this nonlinear equation some expected features of its solution are set forth. A detailed experimental determination is made of the amplitude spectra of various thin plates mounted at zero mean angle of incidence in the test section of a water tunnel and suspended by a torsion spring through their leading edge. The effects of trailing edge geometry and elastic properties of plate support are explored. Data analysis gives interesting confirmation of the formulated equation of motion. The vibration is shown to become self-excited and the degree of two dimensionality of the wake is deduced to be determinative in regard to the severity of the vibration.
Surges in Air Vents Adjacent to Emergency Gates
Authors: McCaig I. W. , Jonker F. H.
Published: November 2011

This paper examines the mechanics of surges in air vents and advances methods for calculating their magnitude. Particular attention is paid to the magnitude of the backsurge which can occur an the air vent behind an intake gate.
Ejector-Nozzle Flow and Thrust
Authors: Weber H. E.
Published: November 2011

An analysis for predicting the secondary and primary flows and the thrust coefficient of ejector nozzles is presented. Particular attention is given to the diverging shroud ejector in which the throat of the secondary stream is formed at a small distance down-stream of the primary nozzle exit; i.e., near the plane of the minimum shroud area. The basic assumption in the analysis is that the shroud is sufficiently short so that the mixing of the two streams is incomplete, and that both streams have isentropic cores. The momentum thickness of the mixing region is obtained from the momentum-integral equation for the turbulent mixing region assuming that momentum and temperature diffuse at the same rate. The momentum thickness at the nozzle exit is related to the initial momentum thickness created by the wall separating the two streams. The exit-momentum thicknesses of the mixing region and the wall are used to obtain the actual thrust coefficient. Experimental data on primary-secondary flow properties and thrust coefficients of a divergent-shroud ejector nozzle show good correlation with the theory.
Crossover Systems Between the Stages of Centrifugal Compressors
Authors: Ellis Gaylord O.
Published: November 2011

The location and orientation of vanes in an annulus are established on the basis of two principles which result from a discussion of simple elbows. These principles are incorporated into a procedure for designing the diffuser vanes in the crossover passage between stages of a centrifugal compressor. To test the proposed design a low-speed model was built and tested and the results compared with a second model which represented a more conventional design.
A Shock-Tube Technique to Determine Steady-Flow Losses of Orifices and Other Duct Elements
Authors: Rudinger George
Published: November 2011

It is shown that a simple shock tube is capable of producing appreciable steady-flow rates through a short duct element, such as an orifice, a valve, or a screen. The flow upstream and downstream of the test element and, therefore, also the losses caused by the test element, can be calculated from known initial conditions in the shock tube and pressure measurements at one point upstream of the element. Experiments to determine the discharge coefficient of a sharp-edged orifice are described as an illustration of the method. The results are in good agreement with available steady-flow data.
Dynamic Response and Control of Multipass Heat Exchangers
Authors: Masubuchi Masami
Published: November 2011

The transfer functions obtained by dynamic analysis of one shell pass and 2, 3, 4, ….., 2n, 2n + 1 tube-pass heat exchangers as a distributed parameter system are presented in dimensionless forms. The heat-exchange processes are found to be governed by the third-order characteristic equations with complex coefficients, and can be solved numerically using a graphical method. The numerical examples are presented to show the clear difference of frequency response for such cases when no solid capacity exists. The analog computer and the experimental results are found to be in good agreement with the theoretical results.
The Design and Analysis of a Servovalve With Flow Feedback
Authors: Bahniuk E. , Lee S.-Y.
Published: November 2011

Almost all conventional servovalves operate on the principle of controlling the position of a four-way or three-way valve made with very high precision with the hope that the flow rate will follow accurately the input signal to the valve. In this paper, an entirely new approach to the servovalve design is presented. A flow signal instead of valve position is used in the feedback loop. This design eliminates the necessity of a high precision valve, gives a greater length of the life expectancy of the valve, and minimizes the effect of load variation as well as supply pressure variation. Dynamic analysis and test results of the flowmeter and the complete valve are given.
Human Body as an Inconstant Heat Source and Its Relation to Determination of Clothes Insulation: Part 1—Descriptive Models of the Heat Source
Authors: Iberall A. S.
Published: November 2011

A precise characterization of the thermal resistance of clothes requires an accurate description of the static and dynamic thermal characteristics of the human-heat source. Experimental measurements on the human have revealed a frequency spectrum of sustained thermal power oscillations that mask theoretical long-time equilibrium adjustments. This points to the number of degrees of freedom that must be involved in the thermoregulation of the human, and the specific nonlinear characteristics of the system. Therefore at best, a resistance model for clothes is possible only as an ohmic relation among time-averaged equilibrium values, and for a specific mode of operation of the system. The validity of this hypothesis, however, has not been proved.
Flow Parameters in Hydrostatic Lubrication for Several Bearing Shapes
Authors: Raynor S. , Charnes A.
Published: November 2011

In the case of hydrostatic lubrication the designer of thrust bearings has to make decisions regarding the shape of pads, location of oil holes, and configuration of oil grooves. In this paper several pad shapes and associated oil inlets were investigated using conformal mapping techniques to obtain the total load-carrying capacity, flow rate of oil, oil-film thickness, pressure and velocity distribution. The results of these calculations permit the designer to approximate his chosen configuration by computed models in order to estimate the flow parameters.
Effect of Hardness, Surface Finish, and Grain Size on Rolling-Contact Fatigue Life of M-50 Bearing Steel
Authors: Baughman R. A.
Published: November 2011

The effect of hardness, surface finish, and grain size upon the compressive rolling-contact fatigue strength of M-50 bearing steel has been studied. Considerable testing on the RC Rig and statistical-treatment methods have been included. A mathematical expression relating these variables to life expectancy is presented and the optimization of these variables is discussed. It is shown that bearing fatigue of M-50 increases by increasing hardness, decreasing surface, and increasing grain size. The optimum life identified occurs at Rc64 hardness, 1.5 rms surface finish, and a grain size of ASTM 2.
The Effect of Ball Bearing Steel Structure on Rolling Friction and Contact Plastic Deformation
Authors: Drutowski Richard C. , Mikus Ernie B.
Published: November 2011

The rolling friction, contact plastic deformation, and elastic limit were determined for SAE 52100 steel structures with retained austenite contents from zero to 18.4 per cent. The force necessary to roll a ball on a plate decreased as the retained austenite was decreased. The contact stress necessary for the initiation of plastic deformation and the elastic limit of the material increased as the retained austenite content decreased from 18.4 to 3.9 per cent. No further change occurred when the retained austenite was reduced to zero. The extent of plastic deformation at very high contact stresses was reduced by the presence of retained austenite contents up to at least 7.4 per cent. These observations were applied to the problem of selecting the best steel structure for an instrument ball bearing.
Torque Produced by Misalignment of Hydrodynamic Gas-Lubricated Journal Bearings
Authors: Ausman J. S.
Published: November 2011

A perturbation analysis is used to find the torque generated by a misaligned journal bearing (or, equivalently, to find the angular displacement of a torque-loaded journal). Results are presented graphically in terms of nondimensional parameters.
A General Flow Graph Technique for the Solution of Multiloop Sampled Systems
Authors: Ash R. , Kim W. H. , Kranc G. M.
Published: November 2011

This paper presents a flow graph approach for analyzing multiloop sampled-data systems. Two techniques for finding the sampled output are examined. These are, first, construction of a “sampled” signal flow graph from the original system; second, a general gain formula which can be directly applied to the original system. The theorems necessary to establish the formula are rigorously proved. The first technique allows two possible modes of solution. The sampled output can be found directly from the sampled flow graph by the use of Mason’s formula, or in case of a more complicated multiloop system, the problem of enumerating nontouching feedback loops can be simplified by the use of topological matrices. Techniques developed in the paper are also applied to the solution of multirate systems.
Theoretical and Experimental Analysis of Hydrostatic Thrust Bearings
Authors: Elwell R. C. , Sternlicht B.
Published: November 2011

This paper presents theoretical and experimental analysis of two types of circular hydrostatic thrust bearings, using incompressible lubricants. Design equations for load-carrying capacity, stiffness, and flow, are given for three different types of flow restriction—orifice, capillary, and constant flow. Experimental verification of the equations is shown. It is seen that each method of restriction imparts its own characteristics on the bearing performance. Constant flow, for instance, results in the stiffest bearing under certain conditions, and capillary restriction is unaffected by temperature changes.
Flow Phenomena of Partially Enclosed Rotating Disks
Authors: Maroti L. A. , Deak G. , Kreith F.
Published: November 2011

The flow of air in the space between a rotating disk and a stationary side wall placed parallel to its surface has been investigated over a range of Reynolds numbers from 3 × 105 to 6 × 106 at clearance-to-diameter ratios from 0.0125 to 0.0625. When the size of the stationary side wall was larger than the diameter of the rotating disk the flow in the gap was found to be periodic; several distinct and separate inflow and outflow regions were observed to rotate in the same direction as the disk, but at a slower speed. The number of flow regions was found to be a function of the disk speed and the gap size. The frictional torque on the housing was also measured and the effect of source flow on the flow pattern was studied qualitatively.
Roughness Effects on Frictional Resistance of Enclosed Rotating Disks
Authors: Nece R. E. , Daily J. W.
Published: November 2011

The effects of surface roughness on the frictional resistance of enclosed rotating disks have been studied experimentally. Torque data were obtained over the range of disk Reynolds numbers 4 × 103 to 6 × 106 for three different relative roughnesses a/k of 1000, 2000, and 3200 at three axial-clearance-to-disk-radius ratios s/a of 0.0227, 0.0609, and 0.112 for a constant, small, radial tip clearance. The existence of four possible basic flow regimes in the axial gap between the disk and casing wall was verified. Empirical expressions have been presented which predict the initial point of onset of turbulence in the flow within the boundary layer on the disk, the point at which the surface roughness becomes fully effective, and the magnitudes of the resistance coefficients in the zone of fully rough turbulent flow. The similarities and differences between smooth and rough-disk torque behavior, and to a limited extent boundary-layer behavior, have been noted.
The Turbulent Boundary Layer at a Plane of Symmetry in a Three-Dimensional Flow
Authors: Johnston James P.
Published: November 2011

Methods for treating a turbulent three-dimensional boundary layer at a plane of symmetry are presented. Reasonable agreement with experiment was achieved by the use of momentum integral techniques in the prediction of momentum thickness, shape factor, wall shear stress, and the location of separation.
Roll-Force and Torque Coefficients for Hot-Strip Steel Mill
Authors: Garudachar B. N. , Peterson H. A.
Published: November 2011

This paper provides results of an analytical and computer investigation to determine the numerical coefficients involved in the roll-force and roll-torque equations pertaining to a single stand in a multistand, tandem, steel rolling mill. To the authors’ knowledge, such information has not appeared in the literature to date. The coefficients for a typical hot mill are compared with those obtained for a typical cold mill. The principles of gage control are discussed. The theories on flat-strip rolling are reviewed briefly.
Burst Strengths and Deformations of Welded Composite Turbine Wheels as Related to Weld Quality and Plasticity Calculations
Authors: Holms A. G. , Repko A. J.
Published: November 2011

Experimental justification is presented for extending an existing rotating disk deformation theory-finite difference plastic flow calculation method to predicting the deformation and fracture of welded composite aircraft gas turbine wheels. Calculated deformations generally equaled but sometimes exceeded measured deformations. Fractures could be predicted for wheels containing no significant defects. Defects observed in fracture surfaces were incomplete penetration, incomplete fusion, porosity, and coarse columnar structure. Of these, incomplete penetration was significantly associated with losses in strength.
Small-Diameter-Orifice Metering
Authors: Filban T. J. , Griffin W. A.
Published: November 2011

Present equations for calculating the flow coefficient in orifice metering are considered invalid for meters smaller than two inches. This paper develops a general expression for the flow coefficient in three-quarter and one-inch meters.
Some Corrosion Effects in Accelerated Cavitation Damage
Authors: Leith W. C. , Thompson A. Lloyd
Published: November 2011

The conjoint mechanical-chemical destruction of metals by accelerated cavitation in a magnetostriction apparatus indicates relative effects of the metal properties (hardness, metallurgical structure, corrosion-fatigue limit) and of the liquid characteristics (temperature, pressure, wettability) which have been confirmed by field experience in hydraulic turbines and in water-cooled diesel cylinder liners.
Bourdon Tube Deflection Characteristics
Authors: Exline Paul G.
Published: November 2011

This paper summarizes data obtained at Oklahoma State University under contract with ASME through RCMPE to measure the deflection characteristics of commercially produced Bourdon tubes. The method of measurement was designed to produce accurate results without including effects of end constraints. Reasonably good agreement with theory was shown. Deviation of the cross-sectional shape of the tube from ideal flat oval shape could not be shown to influence the behavior. An outline of a method of preliminary design of a Bourdon tube is given. Suggestions are made for additional research using stress free electroformed tubes of ideal shapes.
Two-Dimensional Flow With Standing Vortexes in Ducts and Diffusers
Authors: Ringleb Friedrich O.
Published: November 2011

The conditions for the equilibrium of two vortexes in a two-dimensional flow through a duct or diffuser are derived. Potential-flow considerations and a few basic results from viscous-flow theory are used for the discussion of the role of cusps as separation control and trapping devices for standing vortexes. The investigations are applied to cusp diffusers especially with regard to the wind tunnel of the James Forrestal Research Center of Princeton University.
An Experimental Study of Cavitation in a Mixed Flow Pump Impeller
Authors: Wood G. M. , Murphy J. S. , Farquhar J.
Published: November 2011

A mixed flow impeller design was tested with six, five, and four vanes in a closed water loop to study the effects of cavitation on hydraulic performance and the results were compared with the work of other investigators. Two idealized flow models for incipient cavitation were derived to illustrate limits of cavitation design. It was found that both vane blockage and solidity effects are important when designing for optimum cavitation performance. Data showing incidence and speed effects plus the tip static pressure profiles in cavitating and noncavitating flow are also presented.
A Jet Pump Design Theory
Authors: Van Der Lingen T. W.
Published: November 2011

A compressible flow jet pump theory is evolved which can be more easily interpreted for design purposes than existing theories. It consists of a one-dimensional analysis based on the momentum equation and on complete mixing, used in conjunction with an over-all pressure recovery factor which is found experimentally. Tests on a small jet pump are described and from the results it is shown that the overall pressure recovery factor can be related to a single parameter in the analysis for all operating conditions of each general pump configuration. In this way a general method for the correlation of results and for the design of jet pumps is established.
Accelerations and Mean Trajectories in Turbulent Channel Flow
Authors: Irmay S.
Published: November 2011

The author shows that even in steady uniform turbulent channel flow there exist on the average mean accelerations and forces acting on fluid particles. These are computed from the flow equations and Laufer’s data. There exist both normal and axial mean accelerations, the latter highly negative (15g and more) in the dissipative “transition” layer near the wall, elsewhere constant. There most river bed-load and dune sand movement occurs. Mixing and sediment transportation are explained dynamically. Mean shear is shown to exist mainly in the dissipative layer. Mean turbulent trajectories are defined.
Stall Onset on Airfoils at Moderately High Reynolds Number Flows
Authors: Rusak Zvi , Morris Wallace J.
Published: November 2011

The inception of leading-edge stall on two-dimensional smooth thin airfoils at moderately high Reynolds number flows [in the range O(104) to O(106)] is investigated by an asymptotic approach and numerical simulations. The asymptotic theory is based on the work of Rusak (1994) and demonstrates that a subsonic flow about a thin airfoil can be described in terms of an outer region, around most of the airfoil chord, and an inner region, around the nose, that asymptotically match each other. The flow in the outer region is dominated by the classical thin airfoil theory. Scaled (magnified) coordinates and a modified (smaller) Reynolds number are used to correctly account for the nonlinear behavior and extreme velocity changes in the inner region, where both the near stagnation and high suction areas occur. It results in a model (simplified) problem of a uniform flow past a semi-infinite parabola with a far-field circulation governed by a parameter Ã that is related to the airfoil’s angle of attack, nose radius of curvature, and camber and to the flow Mach number. The model parabola problem consists of a compressible and viscous flow described by the steady Navier-Stokes equations. This problem is solved numerically for various values of Ã using a Reynolds-averaged Navier-Stokes flow solver, and utilizing the Spalart-Allmaras viscous turbulent model to account for near-wall turbulence. The value Ãs where a large separation zone first appears in the nose flow concurrent with a sudden increase in the minimum pressure coefficient is determined. The change of Ãs with the modified Reynolds number is determined. These values indicate the stall onset on the airfoil at various flow conditions. The predictions according to this approach show good agreement with results from both numerical simulations and available experimental data of the stall of thin airfoils. This simplified approach provides a criterion to determine the stall angle of airfoils with a parabolic nose and the effect of airfoil’s thickness ratio, nose radius of curvature, camber and flaps, and flow compressibility on the onset of stall. This approach also presents an analysis method that can be used to predict the stall of airfoils with alternative nose geometry.
Experimental Investigation of Pressure Drop Through Ceramic Foams: An Empirical Model for Hot and Cold Flow
Authors: Akbar Shakiba S. , Ebrahimi R. , Shams M.
Published: November 2011

Growing application and use of ceramic foams has intensified the necessity to determine a precise and inexpensive method for prediction of pressure drop through these materials. In this paper, a new experimental model is presented for pressure drop through ceramic foams. In order to measure pressure drop, a set up was made in which air flow rate and temperature varied. Effects of variation in temperature and flow velocity on the pressure drop were investigated through open-cell SiC and Al2O3 foams with different values of porosity and pore density. Results of this study revealed the leading role of parameters such as viscosity, porosity, density, velocity and mean hydraulic diameter of pores of foam. Since there are several parameters affecting the problem, dimensional analysis was adopted as a convenient approach. Euler number, porosity and two Reynolds numbers, one based on the pores’ diameter and the other one based on total bed length, have been shown to be important in the analysis. Finally, an empirical model is developed for the pressure drop which is based on dimensionless numbers.
Blocking Integrin Activation at the α Subunit
Authors: Gough Nancy R.
Published: November 2011

SHARPIN binds to the α subunit of integrins to attenuate activation.
Provoking Preterm Birth
Authors: Foley John F.
Published: November 2011

Mammalian target of rapamycin complex 1 signaling in the uterus contributes to preterm birth in mice.
More Than a Proton Pump
Authors: Ray L. Bryan
Published: November 2011

Cellular sensing of amino acids occurs at the lysosome and is mediated by the vacuolar proton pump.
Fly Guts
Authors: Ash Caroline
Published: November 2011

Successful development of fruit flies depends on a gut bacterium that interacts with its host’s insulin-signaling pathway.
Getting Connected
Authors: Hurtley Stella M.
Published: November 2011

Acetylation of an amino-terminal methionine is important for mediating specific protein-protein interactions.
Population Pharmacokinetics of Voriconazole in Adults
Authors: Hope William W.
Published: November 2011

Voriconazole is a first-line agent for the treatment of invasive fungal infections. The pharmacology of voriconazole is characterized by extensive interindividual variability and nonlinear pharmacokinetics. The population pharmacokinetics of voriconazole in 64 adults is described. The patient population consisted of 21 healthy volunteers, who received a range of intravenous (i.v.) and oral voriconazole regimens, and 43 patients with proven or probable invasive aspergillosis, who received the currently licensed dosage. Voriconazole concentrations were measured using high-performance liquid chromatography (HPLC). The pharmacokinetic data were modeled using a nonparametric methodology and with a nonlinear pharmacokinetic structural model. The extent and consequences of pharmacokinetic variability were explored using Monte Carlo simulation. The relationship between drug exposure and clinical response was explored using logistic regression. Optimal sampling times were identified using D-optimal design. The fit of the nonlinear model was acceptable. Data from the healthy volunteers provided robust estimates for

K
m

and the maximum rate of enzyme activity (
V
max
). The Bayesian parameter estimates were more variable and statistically different in patients than in volunteers. There was a linear relationship between the trough concentration and area under the concentration-time curve (AUC
0-12
). There was no relationship between the AUC
0-12
and clinical response. The original parameter values were readily recapitulated using Monte Carlo simulation. Initial i.v. dosing resulted in higher AUC
0-12
and trough concentrations compared with oral dosing. Sample collection times of 1, 2, 3, 4, 8, and 12 h after an i.v. infusion are maximally informative times for future pharmacokinetic studies.
Discovery and Engineered Overproduction of Antimicrobial Nucleoside Antibiotic A201A from the Deep-Sea Marine Actinomycete Marinactinospora thermotolerans SCSIO 00652
Authors: Zhu Qinghua , Li Jun , Ma Junying , Luo Minghe , Wang Bo , Huang Hongbo , Tian Xinpeng , Li Wenjun , Zhang Si , Zhang Changsheng , Ju Jianhua
Published: November 2011

Marinactinospora thermotolerans
SCSIO 00652, originating from a deep-sea marine sediment of the South China Sea, was discovered to produce antimicrobial nucleoside antibiotic A201A. Whole-genome scanning and annotation strategies enabled us to localize the genes responsible for A201A biosynthesis and to experimentally identify the gene cluster; inactivation of
mtdF
, an oxidoreductase gene within the suspected gene cluster, abolished A201A production. Bioinformatics analysis revealed that a gene designated
mtdA
furthest upstream within the A201A biosynthetic gene cluster encodes a GntR family transcriptional regulator. To determine the role of MtdA in regulating A201A production, the
mtdA
gene was inactivated in frame and the resulting Δ
mtdA
mutant was fermented alongside the wild-type strain as a control. High-performance liquid chromatography (HPLC) analyses of fermentation extracts revealed that the Δ
mtdA
mutant produced A201A in a yield ∼25-fold superior to that of the wild-type strain, thereby demonstrating that
MtdA
is a negative transcriptional regulator governing A201A biosynthesis. By virtue of its high production capacity, the Δ
mtdA
mutant constitutes an ideal host for the efficient large-scale production of A201A. These results validate
M. thermotolerans
as an emerging source of antibacterial agents and highlight the efficiency of metabolic engineering for antibiotic titer improvement.
Directed HIV-1 Evolution of Protease Inhibitor Resistance by Second-Generation Short Hairpin RNAs
Authors: Schopman Nick C. T. , Braun Anja , Berkhout Ben
Published: November 2011

Despite the success of antiretroviral drugs in decreasing AIDS-related mortality, a substantial fraction of HIV-infected patients experience therapy failure due to the emergence of drug-resistant virus variants. For durable inhibition of HIV-1 replication, the emergence of such escape viruses must be controlled. In addition to antiretroviral drugs, RNA interference (RNAi)-based gene therapy can be used to inhibit HIV-1 replication by targeting the viral RNA genome. RNAi is an evolutionary conserved gene silencing mechanism that mediates the sequence-specific breakdown of the targeted mRNA. Here we investigated an alternative strategy combining the activity of a protease inhibitor (PI) with second-generation short hairpin RNAs (shRNAs) designed to specifically block the emergence of PI-resistant HIV-1 variants. We demonstrate that dominant viral escape routes can be effectively blocked by second-generation shRNAs and that virus evolution can be redirected toward less-fit variants. These results are of importance for a deeper understanding of HIV-1 evolution under combined drug and RNAi pressure and may be used to design future therapeutic approaches.
Galectin-1-Specific Inhibitors as a New Class of Compounds To Treat HIV-1 Infection
Authors: St-Pierre Christian , Ouellet Michel , Giguère Denis , Ohtake Reiko , Roy René , Sato Sachiko , Tremblay Michel J.
Published: November 2011

Despite significant improvements, antiretroviral therapies against HIV-1 are plagued by a high frequency of therapeutic failures that have been associated with acquisition of drug resistance. We recently reported that HIV-1 exploits a host glycan binding protein, galectin-1, to increase its attachment to host cells, thereby increasing its overall infectivity in susceptible cells. This finding suggests that host molecules such as galectin-1 could reduce the expected efficiency of HIV-1 drugs targeting early steps of the replicative cycle, such as attachment and entry processes. Thus, new classes of drugs that would interfere with galectin-1/HIV-1 interactions could benefit the current antiretroviral therapy. To further explore this possibility, experiments were conducted to discover leading compounds showing specific inhibition of galectin-1 activity in a cellular model of HIV-1 infection. Three lactoside compounds were found to modestly inhibit the interaction of galectin-1 with primary human CD4
+
T cells. Interestingly, these same inhibitors reduced the galectin-1-mediated increase in HIV-1 attachment to target cells in a much more efficient manner. More important, the tested lactoside derivatives also significantly decreased the galectin-1-dependent enhancement of HIV-1 infection. These observations deserve further attention when considering that the development of new drugs to prevent and treat HIV-1 infection remains a priority.
Differential Effects of Linezolid and Ciprofloxacin on Toxin Production by Bacillus anthracis in an
In Vitro
Pharmacodynamic System
Authors: Louie Arnold , VanScoy Brian D. , Heine Henry S. , Liu Weiguo , Abshire Terry , Holman Kari , Kulawy Robert , Brown David L. , Drusano George L.
Published: November 2011

Bacillus anthracis
causes anthrax. Ciprofloxacin is a gold standard for the treatment of anthrax. Previously, using the non-toxin-producing ΔSterne strain of
B. anthracis
, we demonstrated that linezolid was equivalent to ciprofloxacin for reducing the total (vegetative and spore) bacterial population. With ciprofloxacin therapy, the total population consisted of spores. With linezolid therapy, the population consisted primarily of vegetative bacteria. Linezolid is a protein synthesis inhibitor, while ciprofloxacin is not. Since toxins are produced only by vegetative
B. anthracis
, the effect of linezolid and ciprofloxacin on toxin production is of interest. The effect of simulated clinical regimens of ciprofloxacin and linezolid on the vegetative and spore populations and on toxin production was examined in an
in vitro
pharmacodynamic model over 15 days by using the toxin-producing Sterne strain of
B. anthracis
. Ciprofloxacin and linezolid reduced the total Sterne population at similar rates. With ciprofloxacin therapy, the total Sterne population consisted of spores. With linezolid therapy, >90% of the population was vegetative
B. anthracis
. With ciprofloxacin therapy, toxin was first detectable at 3 h and remained detectable for at least 5 h. Toxin was never detected with linezolid therapy. Ciprofloxacin and linezolid reduced the total Sterne population at similar rates. However, the
B. anthracis
population was primarily spores with ciprofloxacin therapy and was primarily vegetative bacteria with linezolid therapy. Toxin production was detected for at least 5 h with ciprofloxacin therapy but was never detected with linezolid treatment. Linezolid may have an advantage over ciprofloxacin for the treatment of
B. anthracis
infections.
Two Strikingly Different Signaling Pathways Are Induced by Meningococcal Type IV Pili on Endothelial and Epithelial Cells
Authors: Lécuyer Hervé , Nassif Xavier , Coureuil Mathieu
Published: November 2011

Following adhesion on brain microvasculature,
Neisseria meningitidis
is able to cross the blood-brain barrier (BBB) by recruiting the polarity complex and the cell junction proteins, thus allowing the opening of the paracellular route. This feature is the consequence of the activation by the type IV pili of the β
2
-adrenergic receptor/β-arrestin signaling pathway. Here, we have extended this observation to primary peripheral endothelial cells, and we report that the interaction of
N. meningitidis
with the epithelium is strikingly different. The recruitment of the junctional components by
N. meningitidis
is indeed restricted to endothelial cell lines, and no alteration of the cell-cell junctions can be seen in epithelial monolayers following meningococcal type IV pilus-mediated colonization. Consistently, the β
2
-adrenergic receptor/β-arrestin pathway was not hijacked by bacteria adhering on epithelial cells. In addition, we showed that the consequences of the bacterial signaling on epithelial cells is different from that of endothelial cells, since
N. meningitidis
-induced signaling which protects the microcolonies from shear stress on endothelial cells is unable to do so on epithelial cells. Finally, we report that the minor pilin PilV, which has been shown to be essential for endothelial cell response, is not a required bacterial determinant to induce an epithelial cell response. These data demonstrate that even though pilus-mediated signaling induces an apparently similar cortical plaque, in epithelial and endothelial cell lineages, the signaling pathways are strikingly different in both models.
Conflicting objectives in trophy trout recreational fisheries: evaluating trade-offs using an individual-based model
Authors: García-Asorey Martín Ignacio , Escati-Peñaloza Gabriela , Parma Ana María , Pascual Miguel Alberto
Published: November 2011

Standard fisheries models, based on average population metrics, are inadequate for analyzing recreational fisheries where fishing is size-selective and management objectives are related to preserving population size structure. We developed a framework for policy analysis of size-based harvest strategies in recreational fisheries. The framework combines a mixed-effects body growth model and an individual-based harvest model to describe the relationship of growth, mortality, and size structure. Fishery performance is quantified with indicators directly associated to catch-related components of anglers’ satisfaction: yield (kg), population size, and availability of trophy-size fish. We applied our analyses to the steelhead ( Oncorhynchus mykiss ) fishery in the Santa Cruz River (Patagonia, Argentina). Large declines in trophy-size fish are to be expected at fishing mortalities much too low to cause a sizeable decline in recruitment from virgin values. When somatic growth is density-independent, harvest occurs at the expense of other indicators associated with the quality of fishing experienced by individual anglers. Size limits provide a tool to better accommodate harvest without compromising fishing quality. When preserving population size is favored over preserving trophy-size fish, minimum size limits constitute the best policy overall, whereas maximum size limits are best when the emphasis is on preserving trophy-size fish.
Interactions between natural-occurring landscape conditions and land use influencing the abundance of riverine smallmouth bass, Micropterus dolomieu
Authors: Brewer Shannon K. , Rabeni Charles F.
Published: November 2011

This study examined how interactions between natural landscape features and land use influenced the abundance of smallmouth bass, Micropterus dolomieu , in Missouri, USA, streams. Stream segments were placed into one of four groups based on natural-occurring watershed characteristics (soil texture and soil permeability) predicted to relate to smallmouth bass abundance. Within each group, stream segments were assigned forest (n = 3), pasture (n = 3), or urban (n = 3) designations based on the percentages of land use within each watershed. Analyses of variance indicated smallmouth bass densities differed between land use and natural conditions. Decision tree models indicated abundance was highest in forested stream segments and lowest in urban stream segments, regardless of group designation. Land use explained the most variation in decision tree models, but in-channel features of temperature, flow, and sediment also contributed significantly. These results are unique and indicate the importance of natural-occurring watershed conditions in defining the potential of populations and how finer-scale filters interact with land use to further alter population potential. Smallmouth bass has differing vulnerabilities to land-use attributes, and the better the natural watershed conditions are for population success, the more resilient these populations will be when land conversion occurs.
Quantifying importance of marine prey in the diets of two partially anadromous fishes
Authors: Swanson Heidi K. , Kidd Karen A. , Reist James D.
Published: November 2011

The importance of marine prey sources for partially anadromous fishes has received little study and is complicated by considerable plasticity in life history. We determined proportional contributions of marine, freshwater benthic, and freshwater pelagic prey to anadromous and resident Arctic char (Salvelinus alpinus) and lake trout (Salvelinus namaycush) from several partially anadromous populations in the Canadian Arctic. Bayesian mixing models (MixSIR) applied to δ34S and δ13C ratios in lake-specific models indicated that marine prey accounted for 90%–91% of anadromous Arctic char diet and 60%–66% of anadromous lake trout diet. When these estimates were combined with proportion of anadromous individuals in partially anadromous populations, marine food sources accounted for 31%–44% of Arctic char population productivity and 16%–26% of lake trout population productivity. Although future research is needed to refine and quantify variability around these estimates, our results will allow better predictions of the effects of anthropogenic stressors on partially anadromous fishes.
Microarray profiling reveals microRNAs involving soybean resistance to Phytophthora sojae
Authors: Guo Na , Ye Wen-Wu , Wu Xiao-Ling , Shen Dan-Yu , Wang Yuan-Chao , Xing Han , Dou Dao-Long
Published: November 2011

MicroRNAs (miRNAs), a group of small noncoding RNAs, may serve as a class of post-transcriptional regulators in plant immune systems. Nevertheless, little is known about their roles in plant immune response to the oomycete pathogens. To identify miRNAs involved in the response of soybean to Phytophthora sojae , we examined expressional patterns of miRNAs upon infection by P. sojae by microarray analysis in three soybean cultivars: Williams (susceptible), Conrad (quantitative resistance), and Williams 82 (qualitative resistance). Expression of a number of miRNAs was significantly altered upon infection and (or) in the different genotypes. qRT–PCR data with some miRNAs further confirmed the microarray results. Comparative analysis of the selected miRNAs and their targeted gene expression datasets uncovered many reciprocally expressed miRNA–target pairs, which could proposed a feedback circuit between miRNA(s) and protein-coding genes. These results may serve as a basis for further in-depth studies of miRNAs involved in soybean resistance to P. sojae.
The complete mitochondrial genome sequence of Euphausia pacifica (Malacostraca: Euphausiacea) reveals a novel gene order and unusual tandem repeats
Authors: Shen Xin , Wang Haiqing , Wang Minxiao , Liu Bin
Published: November 2011

Euphausiid krill are dominant organisms in the zooplankton population and play a central role in marine ecosystems. Euphausia pacifica (Malacostraca: Euphausiacea) is one of the most important and dominant crustaceans in the North Pacific Ocean. In this paper, we described the gene content, organization, and codon usage of the E. pacifica mitochondrial genome. The mitochondrial genome of E. pacifica is 16 898 bp in length and contains a standard set of 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. Translocation of three transfer RNAs (trnL1, trnL2, and trnW) was found in the E. pacifica mitochondrial genome when comparing with the pancrustacean ground pattern. The rate of Ka/Ks in 13 protein-coding genes among three krill is much less than 1, which indicates a strong purifying selection within this group. The largest noncoding region in the E. pacifica mitochondrial genome contains one section with tandem repeats (4.7 × 154 bp), which are the largest tandem repeats found in malacostracan mitochondrial genomes so far. All analyses based on nucleotide and amino acid data strongly support the monophyly of Stomatopoda, Penaeidae, Caridea, Brachyura, and Euphausiacea. The Bayesian analysis of nucleotide and amino acid datasets strongly supports the close relationship between Euphausiacea and Decapoda, which confirms traditional findings. The maximum likelihood analysis based on amino acid data strongly supports the close relationship between Euphausiacea and Penaeidae, which destroys the monophyly of Decapoda.
A method for estimating wood chip brightness and its applications1This article is a contribution to the series The Role of Sensors in the New Forest Products Industry and Bioeconomy.
Authors: Hu Thomas Q. , Zhao Michelle , Bicho Paul , Losier Pierre
Published: November 2011

Methods for estimating wood chip brightness are important in classifying wood chips in chip piles, stabilizing chip brightness in the pulping process, and reducing bleaching chemical consumption in pulp mills. They also allow us to understand and control factors including outdoor storage in the summer that affect chip and pulp brightness. An accurate off-line method for estimating wood chip brightness has been developed. The method involves a two-stage grinding of air-dried wood chips to powders with small particle sizes and narrow size distributions and measurement of ISO (International Standardization Organization) brightness of the resulting powders. Using this method, ISO brightness values of 20 mill or pilot-plant thermomechanical pulps (TMP) can be linearly correlated, with an r2 value of 0.885, with ISO brightness of the mill or pilot-plant wood chips. Analyses of wood chips and TMP samples taken from a TMP mill every month for 1 year show that both the chip and TMP brightness values are the lowest in July. The method can be used for laboratory analysis of chip brightness, monitoring of chip brightness monthly variation in pulp mills, and checking the accuracy of the on-line chip brightness measurement system.
Stem eccentricity, crown dry mass distribution, and longitudinal growth strain of plantation-grown Eucalyptus nitens after thinning
Authors: Medhurst Jane , Ottenschlaeger Maria , Wood Matthew , Harwood Chris , Beadle Chris , Valencia Juan Carlos
Published: November 2011

Silvicultural treatments that aim to improve tree growth rates also have the potential to alter physical characteristics of the tree stem and thus affect the recovery of solid-wood products. We tested the hypothesis that manifest crown asymmetry in thinned Eucalyptus nitens (Deane & Maiden) Maiden plantations was affecting the development of stem shape. The crown and stem characteristics of 15 E. nitens trees from a 22-year-old thinning trial in northeastern Tasmania were examined. The trial had been thinned 16 years previously. Lowering the intensity of local intraspecific competition through thinning increased the crown dry mass in the north-facing aspect. No direct link was found between crown dry mass distribution and stem eccentricity. The direction of pith eccentricity at 3.0 m height was confined to the northwest and southeast sectors and averaged 11%; the degree of noncircularity in stems at 3.0 m height was strongly related to the ratio of stem diameter to total height squared. These results suggest that the dynamic loading from wind exposure plays a greater role in determining the extent and direction of pith eccentricity and stem cross-sectional circularity in E. nitens than does the static load from asymmetrical crown dry mass distribution.
Recognition of adult images, videos, and web page bags
Authors: Hu Weiming , Zuo Haiqiang , Wu Ou , Chen Yunfei , Zhang Zhongfei , Suter David
Published: November 2011

In this article, we develop an integrated adult-content recognition system which can detect adult images, adult videos, and adult Web page bags, where a Web page bag consists of a Web page and a predefined number of Web pages linked to it through hyperlinks. In our adult image-recognition algorithm, we model skin patches rather than skin pixels, resulting in better results than state-of-the-art algorithms which model skin pixels. In our adult video-recognition algorithm, information from the accompanying audio section around an image in an adult video is used to obtain a prior classification of the image. The algorithm achieves a better performance than the ones which use image information alone or audio information alone. The adult Web page bag recognition is carried out using multi-instance learning based on the combination of classifying texts, images and videos in Web pages. Both the speed and the accuracy for recognizing the Web adult content are increased, in contrast to recognizing Web pages one-by-one.