bluuebunny/crossref_metadata_2025 huggingface dataset:
The Stability of the Normal Modes of Nonlinear Systems With Polynomial Restoring Forces of High Degree
Authors: Atkinson C. P. , Bhatt S. J. , Pacitti Tercio
Published: October 2011

This paper presents methods for determining the exact solutions of certain two-degree-of-freedom nonlinear systems with high-degree polynomial restoring forces. The exact solutions are the normal modes of the systems. A stability analysis of solutions in the normal modes is given. Some systems have normal modes whose stability is a function of amplitude. The stability of complicated systems can be approximated by superposing the stability characteristics of simpler systems. Some experimental confirmation by analog computer is also presented.
The Momentum Integral Approximation for Compressible Magnetogasdynamic Boundary-Layer Flow
Authors: Kauzlarich J. J. , Cambel A. B.
Published: October 2011

The drag of an adiabatic flat plate in an ionized gas for a constant magnetic field applied to the boundary layer on the plate is found by a momentum integral approximation of von Karman. Laminar, two-dimensional flow, zero pressure gradient, small magnetic Reynolds number, and negligible electrical conductivity outside the boundary layer are assumed. The solution is valid in particular to a continuous, perfect-gas plasma, of unitary Prandtl number, and for conditions when the interaction parameter is very small. The solution shows the following effects: The adiabatic wall temperature is independent of the magnetic field; there is an increase in the boundary-layer thickness as the magnetic-field strength is increased; and the viscous drag coefficient decreases whereas the coefficient of total drag increases.
Force Singularities of Shallow Cylindrical Shells
Authors: Jahanshahi A.
Published: October 2011

Singularities for uniformly moving and static concentrated forces on shallow circular cylindrical shells are obtained in terms of the integrals of the products of cylindrical and circular functions. Some relations between the solutions of Helmholtz’s equation and the solutions of bi-Helmholtz’s equation are also given.
Graphical Solution of Quasi-One-Dimensional Foam Flows
Authors: Phinney Ralph
Published: October 2011

Foam is a compressible medium which can have a density corresponding to that of a liquid and a compressibility corresponding to that of a gas. As a result, compressibility effects such as choked flow can be obtained at relatively low velocities. It is not possible to make “Mach number tables” for foam—as it is for gas—since the properties depend on stagnation foam density as well as Mach number. The equations for the flow of foam are nondimensionalized and presented in a form such that universal curves can be produced. This simplification facilitates the manipulation of the equations; for example, the test for a sonic throat follows easily from the formulation, and an approximation is found that applies near the throat. The procedure for calculating the characteristics of one-dimensional duct flow is outlined, and the charts necessary to carry out the graphical computation are shown in this paper.
Critical Speed Damper
Authors: Levy Samuel
Published: October 2011

It is shown that a damper applied to the spherical bearing at the ends of a rotating shaft to damp pitch and yaw motions of the journal bearing can markedly reduce the deflection caused by unbalance near critical speeds. Equations are given for optimizing the damping and for computing the damping moment which must be carried by the journal bearing. It is shown that with optimum damping of a centrally loaded uniform shaft, the load carried by the journal bearing in the critical-speed range is no more than 67 percent greater than it would have been for a rigid shaft. The corresponding moment carried by the journal bearing is less than the amount which would develop at the mid-length of the shaft in the absence of elastic deflections.
Solutions of Heat-Conduction Problems With Nonseparable Domains
Authors: Dicker Daniel , Friedman M. B.
Published: October 2011

A method is presented for obtaining eigenfunctions of and solutions to the transient heat-conduction equation for a wide class of three-dimensional convex hexahedral domains and two-dimensional convex quadrilateral domains having straight or curved boundaries for which separation of variables cannot be applied. The method is employed to solve for the temperature distribution in a trapezoidal domain, initially at zero temperature, the boundaries of which are subjected to suddenly applied values at the initial instant. The solution is obtained in the form of a series and an examination of successive terms indicates fairly rapid convergence; it is found that the one-term solution yields almost as good values as a four-term solution, which is significant since the former is obtained with little effort. An independent method is utilized for obtaining the steady-state solution, i.e., t → ∞, and it is found that all approximations by the former method are substantially equal to the correct value for this case.
Upstream Separation Point for an Internal Corner in a Two-Dimensional Channel Flow
Authors: Barrows J. F.
Published: October 2011

A solution is presented for predicting the upstream separation point in a two-dimensional channel flow in which an obstacle is present. The paper considers only the separation of a laminar boundary layer but could also be applied to the turbulent boundary-layer case. The mathematical model considers free-streamline theory to get the pressure distribution ahead of separation. Go¨rtler’s series solution and Witting’s finite-difference method are then used to predict separation. The theory is checked experimentally.
Approximate Methods for Time-Dependent Gas-Film Lubrication Problems
Authors: Michael W. A.
Published: October 2011

The pressure in a thin film of gas undergoing laminar, isothermal flow is given by the so-called Reynolds equation, a nonlinear, second-order, partial differential equation of parabolic type. The Reynolds equation plays a central role in the theory of gas-film lubrication. This paper is devoted to a study of numerical procedures based upon finite differences for obtaining approximate solutions. A number of explicit, semi-explicit, and implicit difference schemes are examined from the point of view of truncation error, stability, and computational efficiency.
The Effect of Residual Stresses on the Critical Crack Length Predicted by the Griffith Theory
Authors: Jahsman W. E. , Field F. A.
Published: October 2011

The Griffith theory for unstable crack length is modified to take into account the effect of residual (self-equilibrating) stresses. An expression relating the uniform stress, physical properties of the material, critical crack length, and the equilibrating strain energy is derived for a general stress distribution. This expression is used to develop a criterion for spontaneous cracking due to residual stresses alone. A specific numerical example for a parabolic residual-stress distribution in a glass plate is carried out in some detail.
Load-Carrying Capacities of Simply Supported Rectangular Plates
Authors: Shull H. E. , Hu L. W.
Published: October 2011

The upper and lower bounds on the load-carrying capacities of simply supported rectangular plates with uniformly distributed loads are obtained. The usefulness of Tresca’s yield condition in a problem lacking radial symmetry is demonstrated.
On the Buckling of Circular Cylindrical Shells Under Pure Bending
Authors: Seide Paul , Weingarten V. I.
Published: October 2011

The stability of circular cylindrical shells under pure bending is investigated by means of Batdorf’s modified Donnell’s equation and the Galerkin method. The results of this investigation have shown that, contrary to the commonly accepted value, the maximum critical bending stress is for all practical purposes equal to the critical compressive stress.
Size Effect in Brittle Fracture of Notched E-Steel Plates in Tension
Authors: Ludley J. H. , Drucker D. C.
Published: October 2011

Much of our experimental program [1–5] on the initiation of brittle fracture in ordinary structural steel plates has been based strongly on the assumption that a Griffith type of theory is not applicable. Direct experimental evidence is presented here to support that preconceived notion.
On the Stability of the Linearly Related Modes of Certain Nonlinear Two-Degree-of-Freedom Systems
Authors: Atkinson C. P.
Published: October 2011

This paper presents a method for analyzing a pair of coupled nonlinear differential equations of the Duffing type in order to determine whether linearly related modal oscillations of the system are possible. The system has two masses, a coupling spring and two anchor springs. For the systems studied, the anchor springs are symmetric but the masses are not. The method requires the solution of a polynomial of fourth degree which reduces to a quadratic because of the symmetric springs. The roots are a function of the spring constants. When a particular set of spring constants is chosen, roots can be found which are then used to set the necessary mass ratio for linear modal oscillations. Limits on the ranges of spring-constant ratios for real roots and positive-mass ratios are given. A general stability analysis is presented with expressions for the stability in terms of the spring constants and masses. Two specific examples are given.
An Improved Integral Procedure for Compressible Laminar Boundary-Layer Analysis
Authors: Yang Kwang-Tzu
Published: October 2011

A fundamental improvement of any one-parameter integral procedure for compressible laminar boundary-layer analysis is described. It is shown, by means of comparisons with exact solutions covering cases of favorable, zero, and adverse pressure gradients, and of constant and variable surface temperatures with and without heat transfer, that in all cases very significant improvements in the calculated results are attained, and also that this improvement is accomplished simply by evaluating integrals.
Influence Coefficients for Thin Smooth Shells of Revolution Subjected to Symmetric Loads
Authors: Baker B. R. , Cline G. B.
Published: October 2011

The differential equations governing the deformation of shells of revolution of uniform thickness subjected to axisymmetric self-equilibrating edge loads are transformed into a form suitable for asymptotic integration. Asymptotic solutions are obtained for all sufficiently thin shells that possess a smooth meridian curve and that are spherical in the neighborhood of the apex. For design use, influence coefficients are derived and presented graphically as functions of the transformed independent variable ξ. The variation of ξ with the meridional tangent angle φ is given analytically and graphically for several common meridian curves—the parabola, the ellipse, and the sphere.
Interaction Curves for Circular Cylindrical Shells According to the Mises or Tresca Yield Criterion
Authors: Hodge P. G. , Panarelli Joseph
Published: October 2011

A circular cylindrical shell is subjected to uniform internal or external pressure and a constant axial tensile or compressive stress. The interaction curve constituting load combinations which just cause plastic flow of a rigid/perfectly plastic material depends upon the assumed yield criterion of the shell material. Close bounds on the interaction curve are found when the material yields according to either the Tresca or Mises criterion.
Irreversible Thermodynamics of the Thermal Characteristics of Porous Insulators
Authors: Mokadam R. G.
Published: October 2011

The entropy equation contains terms which indicate entropy generation due to two irreversible processes: Heat flow in the presence of temperature gradient, and gas flow in the presence of frictional force. These flows are assumed to be linearly dependent upon the temperature gradient and the frictional force. This assumption includes two cross phenomena: Convective heat transfer (set up by pressure gradient), and free convection (set up by temperature gradient). They are interdependent. Usually the frictional force is equal to the gaseous-phase pressure gradient. When this pressure gradient is zero, the heat flow depends only upon the thermal gradient. By entrapping the gas in the porous medium, the gas flow is stopped. This gives rise to a pressure gradient which sets up a convective heat flow opposing that due to thermal gradient. Consequently, the thermal conductivity of the porous insulator decreases. Experimental work on Tritex insulation material indicated a 22 per cent decrease in thermal conductivity.
On the Influence of Uniform Stress States on the Natural Frequencies of Spherical Shells
Authors: Archer R. R.
Published: October 2011

The influence of uniform tensile and compressive stress states on the natural frequencies of transverse vibrations for shallow spherical shell segments is determined from the general equations for elastokinetic shallow shell problems with longitudinal inertia terms neglected. General frequency determinants are derived and detailed numerical results obtained for a range of shell geometries and stress states.
A Nonhomogeneous Beam in Plane Stress
Authors: Schile R. D.
Published: October 2011

An elementary solution of the plane-stress equation of nonhomogeneous elasticity is derived for the case in which the elastic constants are functions of only one variable. This solution may be applied to the calculation of the stress distribution in a nonhomogeneous beam under an end load or a distributed load. The case of a sandwich beam under an end load is worked out as an illustrative example.
Buckling of a Cylindrical Shell Subjected to Nonuniform External Pressure
Authors: Almroth B. O.
Published: October 2011

A buckling analysis is presented for a circular cylindrical shell subjected to nonuniform external pressure. The general approach is not restricted with respect to the distribution of the lateral pressure. However, the final formulation is specialized for the case in which the pressure distribution is of the form p = p0 + p1 cos φ within a centrally located circumferential band. In the buckling analysis the stability criterion is based on the principle of minimum potential energy, and the Rayleigh-Ritz procedure is used to expand the displacement components in trigonometric series. Buckling pressures are computed in terms of nondimensional parameters and are presented in graphical form.
On the Initial Response of a Spherical Shell to a Concentrated Force
Authors: Medick M. A.
Published: October 2011

This paper is concerned with the initial response of a restricted class of thin elastic shells to localized transient loadings. Attention is restricted to those shells which are essentially spherical and shallow in a neighborhood of the loading. The initial response within this neighborhood can be approximated by the response of a (shallow) spherical shell segment to a concentrated force within the framework of a modified shallow-shell theory.
Minimum Transfer Time for a Power-Limited Rocket
Authors: Leitmann George
Published: October 2011

The problem considered is that of determining the acceleration program leading to minimum transfer time for a power-limited rocket moving between prescribed positions and velocities in a constant gravitational field. It is found that flight must take place at maximum power and that the thrust-acceleration components are linear functions of time. The case of rectilinear transfer between positions of rest is treated in detail, and the results are compared with those previously obtained for a constant-acceleration transfer.
Plastic Stress-Strain Relationships—Further Experiments on the Effect of Loading History
Authors: Parker J. , Kettlewell J.
Published: October 2011

Further tests have been carried out on thin closed-ended tubes of alpha brass subjected to various combinations of torque and internal pressure. The effect of loading, unloading, and reloading along different paths has been investigated. The loading paths were based on a yield function which has previously been found to correlate initial radial loadings for this material, which possesses one degree of anisotropy. However, the results obtained from the second loadings suggest a cross effect which is greater than would be obtained from a nested set of yield surfaces of the foregoing form. There appears to be no evidence to support the presence of a corner in the yield surface.
Stress Distribution at the Fillet of an Internal Flange
Authors: Hofer K. E. , Durelli A. J.
Published: October 2011

This paper deals with the determination of the stress distribution at the fillet of a flange attached internally to a hollow cylinder. A load parallel to the axis of the cylinder and of variable eccentricity acts on a bearing plate which rests on the flange. The strains are measured by means of electrical resistance wire strain gages. The ratios of the mean cylinder diameter to the cylinder wall thickness and of the mean cylinder diameter to the flange thickness are varied. The principal stresses at the fillet are given as functions of these parameters. The experimental results are compared with the stresses calculated on the basis of an approximate theoretical solution for both an axial and an eccentric load.
Evaluation of brachytherapy lung implant dose distributions from photon‐emitting sources due to tissue heterogeneities
Authors: Yang Yun , Rivard Mark J.
Published: October 2011

Purpose:

Photon‐emitting brachytherapy sources are used for permanent implantation to treat lung cancer. However, the current brachytherapy dose calculation formalism assumes a homogeneous water medium without considering the influence of radiation scatter or tissue heterogeneities. The purpose of this study was to determine the dosimetric effects of tissue heterogeneities for permanent lung brachytherapy.

Methods:

The MCNP5 v1.40 radiation transport code was used for Monte Carlo (MC) simulations. Point sources with energies of 0.02, 0.03, 0.05, 0.1, 0.2, and 0.4 MeV were simulated to cover the range of pertinent brachytherapy energies and to glean dosimetric trends independent of specific radionuclide emissions. Source positions from postimplant CT scans of five patient implants were used for source coordinates, with dose normalized to 200 Gy at the center of each implant. With the presence of fibrosis (around the implant), cortical bone, lung, and healthy tissues, dose distributions andPTVDVH were calculated using the MCNP *FMESH4 tally and the NIST mass‐energy absorption coefficients. This process was repeated upon replacing all tissues with water. For all photon energies, 109 histories were simulated to achieve statistical errors (k = 1) typically of 1%.

Results:

The mean PTV doses calculated using tissue heterogeneities for all five patients changed (compared to dose to water) by only a few percent over the examined photon energy range, as did PTV dose at the implant center. ThePTVV100 values were 81.2%, 90.0% (as normalized), 94.3%, 93.9%, 92.7%, and 92.2% for 0.02, 0.03, 0.05, 0.1, 0.2, and 0.4 MeV source photons, respectively. Relative to water, the maximum bone doses were higher by factors of 3.7, 5.1, 5.2, 2.4, 1.2, and 1.0 The maximum lung doses were about 0.98, 0.94, 0.91, 0.94, 0.97, and 0.99. Relative to water, the maximum healthy tissue doses at the mediastinal position were higher by factors of 9.8, 2.2, 1.3, 1.1, 1.1, and 1.1. However, the maximum doses to these healthy tissues were only 3.1, 7.2, 11.3, 10.9, 9.0, and 8.1 Gy while maximum bone doses were 66, 177, 236, 106, 49, and 39 Gy, respectively. Similarly, maximum lung doses were 55, 66, 73, 74, 73, and 73 Gy, respectively.

Conclusions:

The current brachytherapy dose calculation formalism overestimates PTV dose and significantly underestimates doses to bone and healthy tissue. Further investigation using specific brachytherapy source models and patient‐based CT datasets as MC input may indicate whether the observed trends can be generalized for low‐energy lung brachytherapy dosimetry.
Using light to predict fuels-reduction and group-selection effects on succession in Sierran mixed-conifer forest
Authors: Bigelow Seth W. , North Malcolm P. , Salk Carl F.
Published: October 2011

Many semi-arid coniferous forests in western North America have reached historically unprecedented densities over the past 150 years and are dominated by shade-tolerant trees. Silvicultural treatments generally open the canopy but may not restore shade-intolerant species. We determined crossover-point irradiance (CPI) (light at which the height growth rank of pairs of species changes) for seedlings in Sierra Nevada mixed-conifer forest and used these to interpret light environments produced by fuels-reduction thinning and group selection with reserved large trees. Nine of 21 species pairs had well-defined CPIs. The CPI of the most common shade-tolerant and intolerant species (white fir ( Abies concolor (Gordon & Glendl.) Lindl. ex Hildebr.) and ponderosa pine ( Pinus ponderosa Douglas ex P. Lawson & C. Lawson)) was 22.5 mol·m–2·day–1or 41% of full sun. Median understory irradiance increased from 9.2 mol·m–2·day–1(17% full sun) in pretreatment forest to 13 mol·m–2·day–1(24% full sun) in lightly and 15.5 mol·m–2·day–1(28% full sun) in moderately thinned stands and 37 mol·m–2·day–1(67% full sun) in group-selection openings. We estimate that 5%–20% of ground area in lightly to moderately thinned stands would have enough light to favor shade-intolerant over shade-tolerant growth compared with 89% of ground area in group-selection openings. The CPI provides a tool to assess regeneration implications of treatment modification such as increasing heterogeneity of thinning to enhance regeneration or reserving large trees in group-selection openings to maintain wildlife habitat.
ON QUANTUM MARKOV CHAINS ON CAYLEY TREE I: UNIQUENESS OF THE ASSOCIATED CHAIN WITH XY-MODEL ON THE CAYLEY TREE OF ORDER TWO
Authors: ACCARDI LUIGI , MUKHAMEDOV FARRUKH , SABUROV MANSOOR
Published: October 2011

In this paper we study forward quantum Markov chains (QMC) defined on Cayley tree. A construction of such QMC is provided, namely we construct states on finite volumes with boundary conditions, and define QMC as a weak limit of those states which depends on the boundary conditions. Using the provided construction, we investigate QMC associated with XY-model on a Cayley tree of order two. We prove uniqueness of QMC associated with such a model, this means the QMC does not depend on the boundary conditions.
ON SOME CLASSES OF FUNCTIONS AND HYPERCUBES
Authors: Kovachev Dimiter Stoichkov
Published: October 2011

In this paper, some classes of discrete functions of k-valued logic are considered, that depend on sets of their variables in a particular way. The obtained results allow us to construct these functions and to present them in their tabular, analytical or matrix form, as hypercubes, and in particular as Latin hypercubes. Results connected with identifying of variables of some classes of functions are obtained.
Variability in software architecture
Authors: Galster Matthias , Avgeriou Paris , Weyns Danny , Männistö Tomi
Published: October 2011

Variability in software-intensive systems is usually understood as the ability of a software artifact to be changed in order to fit different contexts, environments, or purposes. Software architecture on the other hand determines the structure of a software system, and is described in an architecture description. This description includes the major stakeholders of a software system and their concerns. Variability is reflected in and facilitated through the software architecture. The First International Workshop on Variability in Software Architecture (VARSA) was held jointly with WICSA 2011 in Boulder, Colorado. The goal of the workshop was to explore and advance the state-of-the art in variability in software architecture. It featured four research paper presentations, two invited talks, and three working groups that discussed specific topics. This report summarizes the themes of the workshop, presents the results of the working group discussions, and suggests topics for further research.
Validation of dynamic coupling metrics for object-oriented software
Authors: Gupta Varun
Published: October 2011

Dynamic coupling metrics for object-oriented software provide scope of coupling measurement up to the object level and take into account important and widely used object-oriented features such as inheritance, polymorphism and dynamic binding during measurement. The dynamic measures are computed at run-time, which take into consideration the actual interactions taking place among members of a class. In this paper, an attempt has been made to evaluate dynamic coupling metrics for object-oriented software using formal evaluation framework proposed by Briand et al. A practical and useful coupling measure must satisfy most of the properties given in this framework. The results of this study show that dynamic coupling metrics satisfy all properties and parameters required by the evaluation framework and thus dynamic coupling measures are robust and useful.
Modeling of security requirements for decision information systems
Authors: Khajaria Krishna , Kumar Manoj
Published: October 2011

Data Warehouse (DW) is a decision information system that facilitates decision makers for the fulfillment of strategic decisions (decision making needs) by extracting and integrating data from heterogeneous sources. Due to sensitivity of the information to be maintained in the DW, it becomes important to capture information security goal as a quality goal of the stakeholders for their organization from early stages of DW life cycle. Various requirements engineering techniques have been proposed in the DW literature without paying much attention on security aspect. Recently, AGDI (agent-goal-decision-information) model was proposed to capture decision making needs of the stakeholders for their organization to build a DW, but security issue was not addressed. In this paper, we propose an extension to the AGDI model to capture security aspect (i.e. security goals of the stakeholders) right from the beginning of requirements modeling in order to prevent illegitimate attempts of accessing DW. The application of the proposed extension in the AGDI model has been demonstrated through a CASE study of a University.
Back to Basics at LearnX 2011
Authors: Tracey Ryan
Published: October 2011

In this overview of one of the largest eLearning and training conferences in the Asia Pacific region, spanning the corporate, academic and public service sectors, Ryan Tracey details the back to basics message of LearnX 201.
On grappling with meta-information in the internet
Authors: Callahan Tom , Allman Mark , Rabinovich Michael , Bell Owen
Published: October 2011

The Internet has changed dramatically in recent years. In particular, the fundamental change has occurred in terms of who generates most of the content, the variety of applications used and the diverse ways normal users connect to the Internet. These factors have led to an explosion of the amount of user-specific meta-information that is required to access Internet content (e.g., email addresses, URLs, social graphs). In this paper we describe a foundational service for storing and sharing user-specific meta-information and describe how this new abstraction could be utilized in current and future applications.
Analogue of Lebesgue‐Radon‐Nikodym Theorem with respect to p‐adic q‐Measure on ℤp
Authors: Kim T. , Dolgy D. V. , Lee S. H. , Ryoo C. S.
Published: October 2011

Recently, Lebesgue‐Radon‐Nikodym theorem with respect to fermionic
p‐adic invariant measure on ℤp was studied in Kim. In this paper we will give the analogue
of the Lebesgue‐Radon‐Nikodym theorem with respect to p‐adic q‐measure on ℤp. In special case, q = 1, we can derive the same results in Kim.
Higher‐Order Analytical Attitude Propagation of an Oblate Rigid Body under Gravity‐Gradient Torque
Authors: San-Juan Juan F. , López Luis M. , López Rosario
Published: October 2011

A higher‐order perturbation theory for the rotation of a uniaxial satellite under gravity‐gradient torque demonstrates that known special configurations of the attitude dynamics at which the satellite rotates,
on average, as in a torque‐free state, are only the result of an early truncation of the secular frequencies
of motion. In addition to providing a deeper insight into the dynamics, the higher order of the analytical
solution makes it competitive when compared with the long‐term numerical integration of the equations
of motion.
Characteristics of Correlation Statistics between Droplet Radius and Optical Thickness of Warm Clouds Simulated by a Three-Dimensional Regional-Scale Spectral Bin Microphysics Cloud Model
Authors: Sato Yousuke , Suzuki Kentaroh , Iguchi Takamichi , Choi In-Jin , Kadowaki Hiroyuki , Nakajima Teruyuki
Published: October 2011

Three-dimensional downscaling simulations using a spectral bin microphysics (SBM) model were conducted to investigate the effects of aerosol amount and dynamical stabilities of the atmosphere on the correlation statistics between cloud droplet effective radius (RE) and cloud optical thickness (COT) of warm clouds off the coast of California. The regeneration process of aerosols was implemented into the SBM and was found to be necessary for simulating the satellite-observed microphysical properties of warm clouds by the SBM model used in this study.

The results showed that the aerosol amount changed the correlation statistics in a way that changes the cloud particle number concentration, whereas the inversion height of the boundary layer, which is related to the atmospheric stability and the cloud-top height, changed the correlation statistics in a way that changes the liquid water path. These results showed that the dominant mechanisms that control the correlation statistics are similar to those suggested by previous modeling studies based on two-dimensional idealized simulations. On the other hand, the present three-dimensional modeling was also able to simulate some realistic patterns of the correlation statistics, namely, mixtures of characteristic patterns and the “high-heeled” pattern as observed by satellite remote sensing.
Will Global Warming Suppress North Atlantic Tripole Decadal Variability?
Authors: Yang Yun , Wu Lixin , Fang Changfang
Published: October 2011

In this paper, the modulations of the North Atlantic tripole (NAT) decadal variability from global warming are studied by conducting a series of coupled ocean–atmosphere experiments using the Fast Ocean Atmosphere Model (FOAM). The model reasonably captures the observed NAT decadal variability with a preferred time scale of about 11 years. With the aid of partial-blocking and partial-coupling experiments, it is found that the NAT decadal cycle can be attributed to oceanic planetary wave adjustment in the subtropical basin and ocean–atmosphere coupling over the North Atlantic.

In a doubled CO2 experiment, the spatial pattern of the NAT is preserved; however, the decadal cycle is significantly suppressed. This suppression appears to be associated with the acceleration of oceanic planetary waves due to an increase of buoyancy frequency in global warming. This shortens the time from a decadal to an interannual time scale for the first-mode baroclinic Rossby waves to cross the subtropical North Atlantic basin, the primary memory for the NAT decadal variability in the model. The modeling study also found that the global warming does not modulate the North Atlantic air–sea coupling significantly, but it may be model dependent.
Precipitation Changes near Three Gorges Dam, China. Part I: A Spatiotemporal Validation Analysis
Authors: Zhao Fang , Shepherd Marshall
Published: October 2011

In October 2010, the water level upstream of the Three Gorges Dam (TGD) reached the designated 175-m level. The associated inundation and land use–land cover changes have important implications for water resource management, agriculture, ecosystems, and the hydroclimate. Ultimately, it is important to quantify whether the dam-related changes have altered precipitation patterns. Since rain gauges are limited in the region, satellite-based methods are viable. This study is the first to validate NASA Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) data from 1998 to 2009 using 34 national meteorological rain gauges in the Three Gorges region. Areal average satellite estimates are first verified with areal average rain gauge data both annually and seasonally. Then based on empirical orthogonal functions, the study area is divided into two subregions, and similar validation procedures are performed for both subregions. TMPA data are found to have high correlations with rain gauge data for the whole study area, and correlations for the subregions are only slightly lower. The seasonal analysis yields the lowest correlations for winter. Compared with the gauge data, rainfall is slightly overestimated by about 3 mm month−1. At daily scale, satellite data show good agreement with gauge data for all rain intensity categories except light rain (<1 mm day−1). Spatially, the point-source gauge data are gridded using Thiessen polygons for comparison with satellite data, and the results suggest the satellite-based product may overestimate rainfall in mountainous areas near the reservoir, especially in spring and summer. Overall, the validation results yield strong statistical support for applying satellite rainfall data for hydroclimate studies in this region.
Conditional BDNF release under pathological conditions improves Huntington's disease pathology by delaying neuronal dysfunction
Authors: Giralt Albert , Carretón Olga , Lao-Peregrin Cristina , Martín Eduardo D , Alberch Jordi
Published: October 2011

Background

Brain-Derived Neurotrophic Factor (BDNF) is the main candidate for neuroprotective therapy for Huntington's disease (HD), but its conditional administration is one of its most challenging problems.

Results

Here we used transgenic mice that over-express BDNF under the control of the Glial Fibrillary Acidic Protein (GFAP) promoter (pGFAP-BDNF mice) to test whether up-regulation and release of BDNF, dependent on astrogliosis, could be protective in HD. Thus, we cross-mated pGFAP-BDNF mice with R6/2 mice to generate a double-mutant mouse with mutant huntingtin protein and with a conditional over-expression of BDNF, only under pathological conditions. In these R6/2:pGFAP-BDNF animals, the decrease in striatal BDNF levels induced by mutant huntingtin was prevented in comparison to R6/2 animals at 12 weeks of age. The recovery of the neurotrophin levels in R6/2:pGFAP-BDNF mice correlated with an improvement in several motor coordination tasks and with a significant delay in anxiety and clasping alterations. Therefore, we next examined a possible improvement in cortico-striatal connectivity in R62:pGFAP-BDNF mice. Interestingly, we found that the over-expression of BDNF prevented the decrease of cortico-striatal presynaptic (VGLUT1) and postsynaptic (PSD-95) markers in the R6/2:pGFAP-BDNF striatum. Electrophysiological studies also showed that basal synaptic transmission and synaptic fatigue both improved in R6/2:pGAP-BDNF mice.

Conclusions

These results indicate that the conditional administration of BDNF under the GFAP promoter could become a therapeutic strategy for HD due to its positive effects on synaptic plasticity.
The Brain, The Mind, and the Threat to Public Universities
Authors: Lakoff George
Published: October 2011

George Lakoff’s academic specialty, cognitive linguistics, applies to politics in general; he discusses its special relevance when political issues threaten our universities.
Cytochrome CYP141: A new target for direct detection of Mycobacterium tuberculosis from clinical specimens
Authors: Darban-Sarokhalil Davood , Fooladi Abbas , Bameri Zakaria , Nasiri Mohammad , Feizabadi Mohammad
Published: October 2011

Cytochrome P450 CYP141 is an intermediary metabolic and respiratory protein that interferes with oxidation reduction in Mycobacterium tuberculosis. This conserved protein has also been debated as a hypothetical target for therapeutics. We used the sequences of CYP141 gene to develop a PCR for rapid detection of Mycobacterium tuberculosis from respiratory specimens. The sensitivity of this PCR for culture positive-smear positive and culture positive-smear negative samples were 92% and 62.5%, respectively. The overall sensitivity and specificity of this PCR was 85.7% and 97.8%. As compared with other studies, it appears that the CYP141 gene is a good target for direct detection of M. tuberculosis from respiratory specimens.
Percutaneous, endovascular treatment of innominate artery lesions is a safe and effective procedure
Authors: Paukovits Tamás Mirkó , Nemes Balázs , Hüttl Kálmán , Bérczi Viktor
Published: October 2011

Percutaneous endovascular treatment (transluminar balloon angioplasty with or without stent implantation) of innominate artery lesions has become the treatment of choice prior to surgery in the past decades. Authors present the diagnostics, treatment and follow-up of two patients as examples from their largest series in the literature. A 74-year-old male patient with a history of hyperlipidemia, hypertension, nicotine abuse and lower limb claudication was admitted because of acute upper limb claudication and dizziness. Physical examination revealed blood pressure difference of 30 mmHg between his arms, and poststenotic flow pattern in the common carotid artery with retrograde flow in the vertebral artery on carotid duplex scan. Diagnostic angiography showed 80% stenosis of the innominate artery, which was treated with percutaneous transluminar balloon angioplasty with stent implantation. Follow-up examination at 5 months showed no significant restenosis or neurological complication. The second patient was a 59-year-old smoker female patient with hypertension and type 2 diabetes mellitus, who was evaluated for her upper limb claudication. Initial finding was the absence of radial pulse in the right side. Color duplex scan revealed proximal subocclusion, which was confirmed by angiography. In one stage, balloon angioplasty was made, with immediate pain relief. After 15 months the patient was symptom-free. These two cases demonstrate an excellent outcome of endovascular treatment of innominate artery lesions, as authors already reported in two retrospective studies. Balloon angioplasty with, or without stent deployment appears to be a safe procedure with excellent primary success rate. Review of international studies also indicates that endovascular therapy of the innominate artery is safe and effective. Orv. Hetil., 2011, 152, 1745–1750.
Relative decidability and definability in henselian valued fields
Authors: Flenner Joseph
Published: October 2011

Let (K, v) be a henselian valued field of characteristic 0. Then K admits a definable partition on each piece of which the leading term of a polynomial in one variable can be computed as a definable function of the leading term of a linear map. The main step in obtaining this partition is an answer to the question, given a polynomial f(x) ∈ K[x], what is v(f(x))?

Two applications are given: first, a constructive quantifier elimination relative to the leading terms, suggesting a relative decision procedure; second, a presentation of every definable subset of K as the pullback of a definable set in the leading terms subjected to a linear translation.
Automatic structures of bounded degree revisited
Authors: Kuske Dietrich , Lohrey Markus
Published: October 2011

The first-order theory of a string automatic structure is known to be decidable, but there are examples of string automatic structures with nonelementary first-order theories. We prove that the first-order theory of a string automatic structure of bounded degree is decidable in doubly exponential space (for injective automatic presentations, this holds even uniformly). This result is shown to be optimal since we also present a string automatic structure of bounded degree whose first-order theory is hard for 2EXPSPACE. We prove similar results also for tree automatic structures. These findings close the gaps left open in [28] by improving both the lower and the upper bounds.
On transitive subrelations of binary relations
Authors: Hardin Christopher S.
Published: October 2011

The transitive closure of a binary relation R can be thought of as the best possible approximation of R “from above” by a transitive relation. We consider the question of approximating a relation from below by transitive relations. Our main result is that every thick relation (a relation whose complement contains no infinite chain) on a countable set has a transitive thick subrelation. This allows for a solution to a problem arising from previous work by the author and Alan Taylor. We also exhibit a thick relation on an uncountable set with no transitive thick subrelation.
Role of a combined soluble interleukine-2 receptor alpha (sIL-R2α) and CA-125 serum marker assay for detection of ovarian cancer
Authors: Mačuks Ronalds , Baidekalna Ieva , Nuķe Inta , Doniņa Simona
Published: October 2011

Role of a combined soluble interleukine-2 receptor alpha (sIL-R2α) and CA-125 serum marker assay for detection of ovarian cancer

Detection of ovarian cancer can be improved using a combined diagnostic test consisting of Ca-125 and serum interleukine-2 receptor alpha (sIL-R2α) at a particular threshold. The objective of the study was to evaluate the accuracy of a diagnostic marker assay that combined Ca-125 and serum interleukine-2 receptor alpha. A case-control study of 38 patients with ovarian cancer, 40 patients with benign ovarian diseases and 31 age-matched healthy controls was designed. Ca-125 and sIL-2Rα were detected in patients' serum by standardized chemiluminescent immunometric assays. For Ca-125, a standard cutoff level of 21 U/ml was applied and for sIL-R2α — two cutoff levels were calculated from women included in the control group — one as a mean concentration and the other as an upper limit of a 95% confidence interval. Mean serum concentrations among ovarian cancer patients for CA125 and sIL-2Rα were 265.9 ± 40.2 U/ml and 651.0 ± 50.5 U/ml, respectively. The upper limit of the 95% confidence interval for a healthy control group of women was 304.5 U/ml for sIL-2Rα. Sensitivity and specificity of 89.4% and 85.9% was achieved when CA125 was combined together with sIL-2Rα at a threshold of 304.5U/ml with the condition that both markers are elevated. Sensitivity and specificity of 92.5% and 88.4% was observed when both biomarkers were applied to menopausal women. Serum sIL-2Rα in combination with CA125 can be used as a differential diagnostic test for ovarian cancer at a specific threshold, especially among menopausal women.
Lithofacies-genetic characteristics of sedimentary basins in the foreland of the Pomeranian Stage in the Drawsko Lakeland (northern Poland)
Authors: Paluszkiewicz Ryszard , Paluszkiewicz Renata
Published: October 2011

Lithofacies-genetic characteristics of sedimentary basins in the foreland of the Pomeranian Stage in the Drawsko Lakeland (northern Poland)

The research carried out in the years 1995-98 in the area of the Złocieniec proglacial lake inclined its authors to take a broader view of the operation of proglacial basins in the Drawsko Lakeland (Paluszkiewicz 2004). Glaciolacustrine deposits in the studied lakeland area were discovered by Maksiak and Mróz in 1978. Until that time, the varved deposits at Złocieniec had not been subjected to lithological analysis. The more detailed studies conducted by the present authors in the years 2006-2007 at both Złocieniec and Wierzchowo sites with the help of geo-engineering methods allowed them to show that the two sites with varved clays in this region should be treated as separate sedimentary basins. The basins differ in thickness of varved deposits, in size, and processes responsible for the formation of the rhythmically stratified series.
Structure of aphid communities (Hemiptera: Aphidoidea) in the Kórnik Arboretum near Poznań (West Poland)
Authors: Ratajczak Justyna , Wilkaniec Barbara
Published: October 2011

Structure of aphid communities (Hemiptera: Aphidoidea) in the Kórnik Arboretum near Poznań (West Poland)

The Kórnik Arboretum hosts 106 dendrophilic species of aphids, representing three families: Aphididae, Adelgidae and Phylloxeridae. Phyllaphis fagi is the eudominant there. Subdominants include species of Adelgidae, Eucallipterus tiliae, Tinocallis platani and Myzocallis castanicola. The distribution tail consisted of 101 species, of which 13 were recedents and 88 subrecedents. Such a structure confirms the quite high stability of the community.
Anti-Inflammatory Activity of Alkaloids: An Update from 2000 to 2010
Authors: Souto Augusto Lopes , Tavares Josean Fechine , Da Silva Marcelo Sobral , Diniz Margareth de Fátima Formiga Melo , De Athayde-Filho Petrônio Filgueiras , Barbosa Filho José Maria
Published: October 2011

Many natural substances with proven anti-inflammatory activity have been isolated throughout the years. The aim of this review is to review naturally sourced alkaloids with anti-inflammatory effects reported from 2000 to 2010. The assays were conducted mostly in vivo, and carrageenan-induced pedal edema was the most used experimental model. Of the 49 alkaloids evaluated, 40 demonstrated anti-inflammatory activity. Of these the most studied type were the isoquinolines. This review was based on NAPRALERT data bank, Web of Science and Chemical Abstracts. In this review, 95 references are cited.
Is thermospheric long-term cooling due to CO2 or O3?
Authors: Walsh P. L. , Oliver W. L.
Published: October 2011

Abstract. While greenhouse gases trap heat emanating from the Earth and thereby heat the surface atmosphere, they act as emitters in the high atmosphere and cool the air there. In 1989 Roble and Dickinson (1989) estimated the cooling that would occur in the thermosphere (250–500 km altitude) due to a doubling of greenhouse gas densities. Ever since, long-term data bases have been scoured for evidence of this thermospheric "global cooling." Here we show evidence that the thermosphere did indeed cool over the period 1966–1987, but the data suggest that the cooling accelerated at a "breakpoint year" around 1979 to a rate far larger than may be attributed to greenhouse cooling. This 1979 breakpoint year appears to coincide with a breakpoint year in ozone (O3) column density. Further, the cooling was confined largely to the daytime thermosphere while the nighttime showed only a small trend. These results suggest, first, that the greenhouse cooling of the thermosphere may well not be detectable with current data sets and, second, that the long-term cooling that is clearly seen may be due largely to O3 depletion.
First Hitting Problems for Markov Chains That Converge to a Geometric Brownian Motion
Authors: Lefebvre Mario , Kounta Moussa
Published: October 2011

We consider a discrete-time Markov chain with state space {1,1+Δx,…,1+kΔx=N}. We compute explicitly the probability pj that the chain, starting from 1+jΔx, will hit N before 1, as well as the expected number dj of transitions needed to end the game. In the limit when Δx and the time Δt between the transitions decrease to zero appropriately, the Markov chain tends to a geometric Brownian motion. We show that pj and djΔt tend to the corresponding quantities for the geometric Brownian motion.