bluuebunny/crossref_metadata_2025 huggingface dataset:
NEWTON AND KANT: QUANTITY OF MATTER IN THE METAPHYSICAL FOUNDATIONS OF NATURAL SCIENCE
Authors: FRIEDMAN MICHAEL
Published: September 2012

abstract

Immanuel Kant's Metaphysical Foundations of Natural Science (1786) provides metaphysical foundations for the application of mathematics to empirically given nature. The application that Kant primarily has in mind is that achieved in Isaac Newton's Principia (1687). Thus, Kant's first chapter, the Phoronomy, concerns the mathematization of speed or velocity, and his fourth chapter, the Phenomenology, concerns the empirical application of the Newtonian notions of true or absolute space, time, and motion. This paper concentrates on Kant's second and third chapters—the Dynamics and the Mechanics, respectively—and argues that they are best read as providing a transcendental explanation of the conditions for the possibility of applying the (mathematical) concept of quantity of matter to experience. Kant again has in mind the empirical measures of this quantity that Newton fashions in the Principia, and he aims to make clear, in particular, how Newton achieves a universal measure for all bodies whatsoever by projecting the static quantity of terrestrial weight into the heavens by means of the theory of universal gravitation. Kant is not attempting to prove a priori what Newton has established empirically but, rather, to clarify the character of Newton's mathematization by building Newton's empirical measures into the very concept of matter that is articulated in the Metaphysical Foundations.
NEWTON AND THE MECHANICAL PHILOSOPHY: GRAVITATION AS THE BALANCE OF THE HEAVENS
Authors: MACHAMER PETER , MCGUIRE J. E. , KOCHIRAS HYLARIE
Published: September 2012

abstract

We argue that Isaac Newton really is best understood as being in the tradition of the Mechanical Philosophy and, further, that Newton saw himself as being in this tradition. But the tradition as Newton understands it is not that of Robert Boyle and many others, for whom the Mechanical Philosophy was defined by contact action and a corpuscularean theory of matter. Instead, as we argue in this paper, Newton interpreted and extended the Mechanical Philosophy's slogan “matter and motion” in reference to the long and distinguished tradition of mixed mathematics and the study of simple machines.
NEWTON AND PROCLUS: GEOMETRY, IMAGINATION, AND KNOWING SPACE
Authors: DOMSKI MARY
Published: September 2012

abstract

I aim to clarify the argument for space that Newton presents inDe Gravitatione(composed prior to 1687) by putting Newton's remarks into conversation with the account of geometrical knowledge found in Proclus'sCommentary on the First Book of Euclid'sElements (ca. 450). What I highlight is that both Newton and Proclus adopt an epistemic progression (or “order of knowing”) according to which geometrical knowledge necessarily precedes our knowledge of metaphysical truths concerning the ontological state of affairs. As I argue, Newton's commitment to this order of knowing clarifies the interplay of the imagination and understanding in geometrical inquiry and illuminates how geometrical knowledge of space can lead to knowledge that space depends on and is related to God. In general, appreciating the Proclean elements of Newton's argument brings added light to the significance of geometrical inquiry for his general natural philosophical program and grants us insight into the philosophical grounding for the notion of absolute space that is presented in thePrincipia mathematica(1687).
NEWTON AND DESCARTES: THEOLOGY AND NATURAL PHILOSOPHY
Authors: JANIAK ANDREW
Published: September 2012

abstract

Scholars have long recognized that Newton regarded Descartes as his principal philosophical interlocutor when composing the first edition of Philosophiae Naturalis Principia Mathematica in 1687. The arguments in the Scholium on space and time, for instance, can profitably be interpreted as focusing on the conception of space and motion in part two of Descartes's Principles of Philosophy (1644). What is less well known, however, is that this Cartesian conception, along with Descartes's attempt to avoid Galileo's fate in 1633, serves as an essential background to understanding Newton's own (poorly understood) view of the theological implications of his theory of space and motion. In particular, after withdrawing Le Monde from publication in 1633 because of its Copernican leanings, Descartes later introduced what some regard as a “fudge factor” into the theory of motion in the Principles: from an ordinary perspective the earth does move; but from a philosophical one, it does not. This background indicates the novelty and originality of Newton's own attempt to explicate how scriptural passages concerning the motions of the heavenly bodies can be reconciled with the philosophical views he developed during the 1680s. New evidence from archival sources and correspondence supports this argument, shedding light on the Scholium and on Newton's conception of philosophy's relation to theology.
NEWTON AND HAMILTON: IN DEFENSE OF TRUTH IN ALGEBRA
Authors: FOLINA JANET
Published: September 2012

abstract

Although it is clear that Sir William Rowan Hamilton supported a Kantian account of algebra, I argue that there is an important sense in which Hamilton's philosophy of mathematics can be situated in the Newtonian tradition. Drawing from both Niccolo Guicciardini's (2009) and Stephen Gaukroger's (2010) readings of the Newton–Leibniz controversy over the calculus, I aim to show that the very epistemic ideals that underpin Newton's argument for the superiority of geometry over algebra also motivate Hamilton's philosophy of algebra. Namely, Hamilton's defense of algebra, like Newton's defense of geometry, is driven by the claim that a mathematical science must have a proper object and thus a basis in truth. In particular, Hamilton aims to show that algebra is not a mere language, or tool, or a mere “art”; instead, he argues, algebra is a bona fide mathematical science, like geometry, because its methods also provide true and accurate insight into a genuine subject matter, namely, the pure form of temporal intuition.
NEWTON AND SPINOZA: ON MOTION AND MATTER (AND GOD, OF COURSE)
Authors: SCHLIESSER ERIC
Published: September 2012

abstract

This study explores several arguments against Spinoza's philosophy that were developed by Henry More, Samuel Clarke, and Colin Maclaurin. In the arguments on which I focus, More, Clarke, and Maclaurin aim to establish the existence of an immaterial and intelligent God precisely by showing that Spinoza does not have the resources to adequately explain the origin of motion. Attending to these criticisms grants us a deeper appreciation for how the authority derived from the empirical success of Newton's enterprise was used to settle debates within philosophy. What I emphasize is that in the progression from More to Clarke to Maclaurin, key Newtonian concepts from thePrincipia(1687), such as motion, atomism, and the vacuum, are introduced and exploited in order to challenge the account of matter and motion that is presented in Spinoza'sEthics(1677). Building on this treatment, I use the arguments from More and Clarke especially to help discern the anti‐Spinozism that can be detected in Newton's General Scholium (1713). Ultimately, the Newtonian criticisms that I detail offer us a more nuanced view of the problems that plague Spinoza's philosophy, and they also challenge the idea that Spinoza seamlessly fits into a progressive narrative about the scientific revolution.
Accelerated vaccination schedule provides protective levels of antibody and complete herd immunity to equine influenza
Authors: EL‐HAGE C. M. , SAVAGE C. J. , MINKE J. M. , FICORILLI N. P. , WATSON J. , GILKERSON J. R.
Published: September 2012

Reasons for performing study:During the 2007 Australian equine influenza (EI) outbreak, an accelerated primary course 14 day intervaccination schedule was proposed, but not widely implemented. Expert opinion was divided as to the efficacy of such a schedule given the lack of published data. This study determined the level and duration of humoral immunity following administration of a recombinant canarypox‐vectored vaccine (ALVAC‐EIV) with a primary intervaccination interval of 14 days and booster at 105 days.

Objectives:To examine whether protective levels of immunity of adequate duration were achieved following a primary course reduced from a minimum interval of 28 to 14 days. Antibody responses to 2 H3N8 American lineage virus strains (including A/equine/Sydney/6085/2007) were assessed and compared to previous challenge studies using ALVAC‐EIV at conventional intervaccination intervals.

Methods:Fourteen Thoroughbred horses and 2 ponies from a rural racehorse training property in Victoria, Australia, were vaccinated with ALVAC‐EIV on Days 0, 14 and 105. Serial blood samples were collected over the next 32 weeks and tested with haemagglutination inhibition and single radial haemolysis (SRH) in full assays to evaluate the serological response.

Results:All horses and ponies responded to the accelerated ALVAC‐EIV vaccination schedule. Mean SRH antibodies remained above those consistent with clinical protection for the duration of the study period. All vaccinates demonstrated high SRH antibodies 14 days following V2, thereby achieving 100% herd immunity to homologous viral challenge.

Conclusions:An accelerated vaccination schedule conferred long‐lasting protective antibody levels despite a >50% reduction in the recommended V1–V2 interval.

Potential relevance:High levels of rapidly acquired herd immunity are critical in containing an outbreak of such a highly contagious pathogen as EIV. In a strategic vaccination programme, it is important that horses remain protected for sufficient time to allow control programmes to succeed. An accelerated 14 day primary course intervaccination interval and booster at 105 days achieves both of these objectives.
The effect of collection and extension on tarsal flexion and fetlock extension at trot
Authors: WALKER V. A. , WALTERS J. M. , GRIFFITH L. , MURRAY R. C.
Published: September 2012

A recent epidemiological study indicated that various factors may be related to injury in dressage horses, but the mechanism by which these injuries occur has yet to be determined. The suspensory ligament (SL) is a frequent site of injury, and it is assumed that greatest strain is placed on this structure in collected trot; this has yet to be proved conclusively. The study aimed to investigate the effect of collected and extended trot on the hindlimb movement pattern. Four dressage horses were fitted with markers and inertial motion sensors (IMS). High‐speed video was obtained for 2 strides on each rein in collected and extended trot on 3 different surfaces: waxed outdoor; sand/plastic granules; and waxed indoor. Maximal tarsal flexion during stance and distal metatarsal coronary band ratio (MTCR), representing fetlock extension, were determined. Inertial motion sensor data determined stride duration, speed and stride length. Data were compared between collection and extension within horses on each surface, and compared between surfaces. Collected trot had significantly lower speed and stride length but longer stride duration than extended trot on all surfaces. All horses had less tarsal flexion and fetlock extension in collected compared with extended trot (P<0.05), which is likely to increase SL loading. The study findings indicate that extended trot may increase SL strain, providing a possible explanation for the high incidence of SL injury in horses trained for extravagant movement. It is possible that substantial use of extended trot could be a risk factor for development of suspensory desmitis, which might be one contributory factor in the prevalence of suspensory desmitis in young horses repeatedly undertaking extravagant movement.
Comparison of prognosis of separated and non‐separated tooth autotransplantation
Authors: Yoshino K. , Kariya N. , Namura D. , Noji I. , Mitsuhashi K. , Kimura H. , Fukuda A. , Kikukawa I. , Hayashi T. , Yamazaki N. , Kimura M. , Tsukiyama K. , Yamamoto K. , Fukuyama A. , Hidaka D. , Shinoda J. , Mibu H. , Shimakura Y. , Saito A. , Ikumi S. , Umehara K. , Kamei F. , Fukuda H. , Toake T. , Takahashi Y. , Miyata Y. , Shioji S. , Toyoda M. , Hattori N. , Nishihara H. , Matsushima R. , Nishibori M. , Hokkedo O. , Nojima M. , Kimura T. , Fujiseki M. , Okudaira S. , Tanabe K. , Nakano M. , Ito K. , Kuroda M. , Matsukubo T.
Published: September 2012

The aim of this study was to compare the prognosis of separated and non‐separated tooth autotransplantation of the upper first and second molars with complete root formation undertaken at dental clinics. The participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. Data on a total of 708 teeth from 637 patients were collected. This study analysed 35 separated teeth and 22 non‐separated teeth of 47 participants ranging from 27 to 76 years of age (mean age: 55·0 years) after data screening and elimination. The cumulative post‐transplantation survival rate at 10 years was 77·1% for separated teeth and 63·6% for non‐separated teeth as calculated with the Kaplan–Meier method. There were no significant differences between separated teeth and non‐separated teeth in a log rank test (P = 0·687). Separated‐tooth autotransplantation can help fill narrow recipient sites and increase occlusal supporting zones, but the clinical success rate was only 48·6%. Although transplantation of teeth with complete root formation has limited prognosis, transplantation of upper first and second molars, whether separated or non‐separated, is a viable option to replace missing teeth.
The pharmacokinetics of cytarabine in dogs when administered via subcutaneous and continuous intravenous infusion routes
Authors: Crook K. I. , Early P. J. , Messenger K. M. , Muñana K. R. , Gallagher R. , Papich M. G.
Published: September 2012

This crossover study compared the pharmacokinetics of cytarabine in six healthy dogs following intravenous constant rate infusion (CRI) and subcutaneous (SC) administrations, as these are two routes of administration commonly employed in the treatment of meningoencephalitis of unknown etiology. Each dog received aSCcytarabine injection of 50 mg/m2or an 8 hCRIof 25 mg/m2per hour, with a 7‐day washout before receiving the alternative treatment. Blood samples were collected for 16 h afterCRIinitiation and for 8 h afterSCinjection. Plasma concentrations were measured by high‐pressure liquid chromatography (HPLC). Pharmacokinetic parameters were estimated using the best‐fit compartmental analysis for bothCRIandSCroutes. Terminal half‐life (T½) of cytarabine was 1.35 ± 0.3 and 1.15 ± 0.13 h afterSCadministration andCRI, respectively. Mean peak concentration (Cmax) was 2.88 and 2.80 μg/mL forSCandCRIadministration, respectively. Volume of distribution was 0.66 ± 0.07 l/kg. The 8‐hCRIproduced steady‐state plasma concentrations as determined by consecutive measurement that did not decline until the end of the infusion. TheSCadministration did not achieve steady‐state concentrations because cytarabine administered by this route was rapidly absorbed and eliminated quickly. The steady state achieved with the cytarabineCRImay produce a more prolonged exposure of cytarabine at cytotoxic levels in plasma compared to the concentrations afterSCadministration.
Endocannabinoids mediate the glucocorticoid‐induced inhibition of excitatory synaptic transmission to dorsal raphe serotonin neurons
Authors: Wang Jue , Shen Roh‐Yu , Haj‐Dahmane Samir
Published: September 2012

Key points

The modulation of the serotonin system by glucocorticoids plays a central role in the regulation of stress responses. However, the mechanisms by which glucocorticoids regulate the excitability of dorsal raphe serotonin neurons remain unknown.

In this study, we show that glucocorticoids rapidly inhibit glutamatergic synaptic transmission to serotonin neurons by reducing glutamate release.

The rapid inhibition of glutamate release is not signalled by classical intracellular glucocorticoid receptors, but rather by putative membrane‐located G‐protein‐coupled receptors.

Activation of the membrane‐located G‐protein‐coupled receptors increases endocannabinoid signalling, which in turn mediates the inhibition of glutamatergic transmission in the dorsal raphe.

In the dorsal raphe, glucocorticoids increase endocannabinoid tone by inhibiting cyclooxygenase‐2.

Abstract  Glucocorticoids play a critical role in the modulation of stress responses by controlling the function of the serotonin (5‐HT) system. However, the precise effects of glucocorticoids on the excitability of dorsal raphe (DR) 5‐HT neurons remain unknown. In this study, we investigated the effects of glucocorticoids on excitatory synaptic transmission to putative DR 5‐HT neurons. We found that corticosterone or the synthetic glucocorticoid agonist dexamethasone rapidly suppressed glutamatergic synaptic transmission to DR 5‐HT neurons by inhibiting glutamate release in the DR. This inhibitory effect was mimicked by membrane‐impermeable glucocorticoids, indicating the involvement of membrane‐located corticosteroid receptors. The glucocorticoid‐induced inhibition of glutamatergic transmission was mediated by the activation of postsynaptic G‐protein‐coupled receptors and signalled by retrograde endocannabinoid (eCB) messengers. Examination of the downstream mechanisms revealed that glucocorticoids enhance eCB signalling via an inhibition of cyclooxygenase‐2. Together, these findings unravel a novel mechanism by which glucocorticoids control the excitability of DR 5‐HT neurons and provide new insight into the rapid effects of stress hormones on the function of the 5‐HT system.
Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males
Authors: Cocks Matthew , Shaw Christopher S. , Shepherd Sam O. , Fisher James P. , Ranasinghe Aaron M. , Barker Thomas A. , Tipton Kevin D. , Wagenmakers Anton J. M.
Published: September 2012

Key point

Optimal vascular function is critical for health, and endurance training (ET) has previously been shown to be an effective method of improving this.

Sprint interval training (SIT) has been proposed as a time efficient alternative to ET but its effect on skeletal muscle microvasculature has not been studied and no direct comparison with ET has been made.

ET and SIT in this study were equally effective at decreasing arterial stiffness and increasing skeletal muscle capillarisation and eNOS content.

The main results suggest that both training modes improve skeletal muscle microvascular and macrovascular function, with SIT being a time efficient alternative.

Abstract  Sprint interval training (SIT) has been proposed as a time efficient alternative to endurance training (ET) for increasing skeletal muscle oxidative capacity and improving certain cardiovascular functions. In this study we sought to make the first comparisons of the structural and endothelial enzymatic changes in skeletal muscle microvessels in response to ET and SIT. Sixteen young sedentary males (age 21 ± SEM 0.7 years, BMI 23.8 ± SEM 0.7 kg m−2) were randomly assigned to 6 weeks of ET (40–60 min cycling at ∼65%, 5 times per week) or SIT (4–6 Wingate tests, 3 times per week). Muscle biopsies were taken from the m. vastus lateralis before and following 60 min cycling at 65% to measure muscle microvascular endothelial eNOS content, eNOS serine1177 phosphorylation, NOX2 content and capillarisation using quantitative immunofluorescence microscopy. Whole body insulin sensitivity, arterial stiffness and blood pressure were also assessed. ET and SIT increased skeletal muscle microvascular eNOS content (ET 14%; P < 0.05, SIT 36%; P < 0.05), with a significantly greater increase observed following SIT (P < 0.05). Sixty minutes of moderate intensity exercise increased eNOS ser1177 phosphorylation in all instances (P < 0.05), but basal and post‐exercise eNOS ser1177 phosphorylation was lower following both training modes. All microscopy measures of skeletal muscle capillarisation (P < 0.05) were increased with SIT or ET, while neither endothelial nor sarcolemmal NOX2 was changed. Both training modes reduced aortic stiffness and increased whole body insulin sensitivity (P < 0.05). In conclusion, in sedentary males SIT and ET are effective in improving muscle microvascular density and eNOS protein content.
Direct Numerical Simulations of Wake-Perturbed Separated Boundary Layers
Authors: Gungor Ayse G. , Simens Mark P. , Jiménez Javier
Published: September 2012

A wake-perturbed flat plate boundary layer with a streamwise pressure distribution similar to those encountered on the suction side of typical low-pressure turbine blades is investigated by direct numerical simulation. The laminar boundary layer separates due to a strong adverse pressure gradient induced by suction along the upper simulation boundary, transitions, and reattaches while still subject to the adverse pressure gradient. Various simulations are performed with different wake passing frequencies, corresponding to the Strouhal number 0.0043< fθb/ΔU <0.0496 and wake profiles. The wake profile is changed by varying its maximum velocity defect and its symmetry. Results indicate that the separation and reattachment points, as well as the subsequent boundary layer development, are mainly affected by the frequency, but that the wake shape and intensity have little effect, and that the forcing is effective as long as the wake-passing period is shorter than the bubble-regeneration time. Moreover, the effect of the different frequencies can be predicted from a single experiment in which the separation bubble is allowed to reform after having been reduced by wake perturbations. The stability characteristics of the mean flows resulting from the forcing at different frequencies are evaluated in terms of local linear stability analysis based on the Orr-Sommerfeld equation.
Unsteady Acoustic Forcing on an Impeller Due to Coupled Blade Row Interactions
Authors: Richards Simon K. , Ramakrishnan Kishore , Shieh Chingwei M. , Moyroud François , Picavet Alain , Ballarini Valeria , Michelassi Vittorio
Published: September 2012

This article contains an investigation of the unsteady acoustic forcing on a centrifugal impeller due to coupled blade row interactions. Selected results from an aeromechanical test campaign on a GE Oil and Gas centrifugal compressor stage with a vaneless diffuser are presented. The most commonly encountered sources of impeller excitation due to upstream wake interaction were identified and observed in the testing campaign. A 30/rev excitation corresponding to the sum of upstream and downstream vane counts caused significant trailing edge vibratory stress amplitudes. Due to the large spacing between the impeller and the return channel vanes, this 30/rev excitation was suspected to be caused by an aero-acoustic excitation rather than a potential disturbance. The origin of this aero-acoustic excitation was deduced from an acoustic analysis of the unsteady compressor flow derived from CFD. The analysis revealed a complex excitation mechanism caused by impeller interaction with the upstream vane row wakes and subsequent acoustic wave reflection from the downstream return channel vanes. The findings show it is important to account for aero-acoustic forcing in the aeromechanical design of low pressure ratio centrifugal compressor stages.
Fan Root Aerodynamics for Large Bypass Gas Turbine Engines: Influence on the Engine Performance and 3D Design
Authors: Zamboni Giulio , Xu Liping
Published: September 2012

The exit flow field of the fan root of large turbofan engines defines the inlet conditions to the core compressor. This in turn could have significant impact to the performance of the core compressor. This study is aimed to resolve two related issues concerning the impact of the fan root flow on the core compressor performance: to establish the effect of an increased loss at the inlet on the engine specific fuel consumption (SFC) and to assess the effect of the radial distribution of the fan root flow on the engine performance. With understanding of these issues, the geometric parameters and design details which can produce a more uniform core flow at the exit of the fan stage module can be identified. The fan root flow is analyzed with methods of different complexity and fidelity. A simple cycle analysis is used to assess the impact on engine SFC of a stagnation pressure deficit at the fan root; a throughflow code is used for the preliminary study of the curvature effect of the root flow path, and 3D RANS CFD calculations are then used to simulate the flow path from the inlet of the fan to the first stage of the core compressor. The adequacy of the application of the numerical code in this case has been assessed and confirmed by the comparison with the experimental data for two rig configurations. The results of this study show that the flow at the fan hub region is very complex and dominated by 3D effects. The interaction of the secondary flow with real geometries, such as leakage flows, is found to have a strong detrimental effect on the core performance. The curvature of the hub end wall is a key parameter controlling the fan root flow topology; it influences the strength of the secondary flow, the spanwise distribution of the flow, and its sensitivity to leakage flow. With this understanding, it is possible to redesign of the fan hub flow path to reduce the loss generation by a significant amount.
A Model for Cylindrical Hole Film Cooling—Part I: A Correlation for Jet-Flow With Application to Film Cooling
Authors: Kampe Tilman auf dem , Völker Stefan , Zehe Frank
Published: September 2012

This paper presents a model to predict the flow structure of cooling flows emanating from cylindrical holes. It is based on a correlation of the flow field with characteristic film cooling parameters. In a previous paper, the authors reported on the dependence of the film-jet on flow parameters, such as blowing ratio, density ratio, free stream Mach number, and turbulence intensity. The present paper extends these results by including the effect of geometry parameters, namely length-to-diameter ratio and inclination angle. All correlations are derived based on a numerical parameter study using a validated 3D-CFD model of a flat plate, scaled to engine conditions. To investigate the effects of the geometry parameters as well as their interaction with the aforementioned flow parameters, a DOE varying all parameters was performed. Results from these numerical investigations are used to correlate the flow-field in the film-jet with the underlying film cooling parameters. The focus of this paper is to demonstrate the predictive capability of the proposed correlations. It provides the basis for a model to simulate film cooling flows in 3D-CFD without meshing the cooling hole geometry, which is presented in the second part of this paper.
A Model for Cylindrical Hole Film Cooling—Part II: Model Formulation, Implementation and Results
Authors: Kampe Tilman auf dem , Völker Stefan
Published: September 2012

A model to simulate flows ejected from cylindrical film cooling holes in 3D-CFD without meshing the cooling hole geometry has been developed. It uses a correlation-based prediction of the complete three-dimensional flow field in the vicinity of a film hole exit based on characteristic film cooling parameters that is presented in part I of this two-part paper. The model describes the film-jet in terms of its shape and the distribution of temperature and velocity components within the film-jet body. For example, the characteristic counter-rotating vortex pair in the film-jet is modeled. Adding source terms to the transport equations for mass, momentum, and energy locally, the correlation-based prediction of the film-jet flow field is imposed onto a 3D-CFD simulation. Source terms are specified in the vicinity of a film hole exit, within a region representative of the volume occupied by the film jet. Each node within this source volume is treated individually in order to model the complex flow structure of the film-jet. The model has successfully been implemented in a commercial CFD code. Its general applicability has been tested and proven. The model’s predictive capability is compared to detailed CFD calculations and experimental investigations. A grid requirement study has been conducted, showing that the film cooling model delivers reasonable predictions of the surface temperature distributions downstream of the ejection location using relatively coarse grids. A minimum grid resolution requirement has been identified.
Symbolic and Numeric Computation of Optimal Initial Velocity in a Wave Equation
Authors: Saraç Yeşim
Published: September 2012

We get symbolic and numeric solutions developing a MAPLE® program which uses the initial velocity on the state variable of a wave equation as control function. Solution of this problem implies the minimization at the final time of the distance measured in a suitable norm between the solution of the problem and a given target. An iterative algorithm is constructed to compute the required optimal control as the limit of a suitable subsequence of controls. Results are tested with some numerical examples.
Description and Validation of a Finite Element Model of Backflow During Infusion Into a Brain Tissue Phantom
Authors: García José J. , Molano Ana Belly , Smith Joshua H.
Published: September 2012

An axisymmetric biphasic finite element model is proposed to simulate the backflow that develops around the external boundary of the catheter during flow-controlled infusions. The model includes both material and geometric nonlinearities and special treatments for the nonlinear boundary conditions used to represent the forward flow from the catheter tip and the axial backflow that occurs in the annular gap that develops as the porous medium detaches from the catheter. Specifically, a layer of elements with high hydraulic conductivity and low Young’s modulus was used to represent the nonlinear boundary condition for the forward flow, and another layer of elements with axial hydraulic conductivity consistent with Poiseuille flow was used to represent the backflow. Validation of the model was performed by modifying the elastic properties of the latter layer to fit published experimental values for the backflow length and maximum fluid pressure obtained during infusions into agarose gels undertaken with a 0.98-mm-radius catheter. Next, the finite element model predictions showed good agreement with independent experimental data obtained for 0.5-mm-radius and 0.33-mm-radius catheters. Compared to analytical models developed by others, this finite element model predicts a smaller backflow length, a larger fluid pressure, and a substantially larger percentage of forward flow. This latter difference can be explained by the important axial flow in the tissue that is not considered in the analytical models. These results may provide valuable guidelines to optimize protocols during future clinical studies. The model can be extended to describe infusions in brain tissue and in patient-specific geometries.
Coupling FEM With Parameter Continuation for Analysis of Bifurcations of Periodic Responses in Nonlinear Structures
Authors: Formica Giovanni , Arena Andrea , Lacarbonara Walter , Dankowicz Harry
Published: September 2012

A computational framework is proposed to perform parameter continuation of periodic solutions of nonlinear, distributed-parameter systems represented by partial differential equations with time-dependent coefficients and excitations. The path-following procedure, encoded in the general-purpose Matlab-based computational continuation core (referred to below as coco), employs only the evaluation of the vector field of an appropriate spatial discretization; for example as formulated through an explicit finite-element discretization or through reliance on a black-box discretization. An original contribution of this paper is a systematic treatment of the coupling of coco with Comsolmultiphysics, demonstrating the great flexibility afforded by this computational framework. Comsolmultiphysics provides embedded discretization algorithms capable of accommodating a great variety of mechanical/physical assumptions and multiphysics interactions. Within this framework, it is shown that a concurrent bifurcation analysis may be carried out together with parameter continuation of the corresponding monodromy matrices. As a case study, we consider a nonlinear beam, subject to a harmonic, transverse direct excitation for two different sets of boundary conditions and demonstrate how the proposed approach may be able to generate results for a variety of structural models with great ease. The numerical results include primary-resonance, frequency-response curves together with their stability and two-parameter analysis of multistability regions bounded by the loci of fold bifurcations that occur along the resonance curves. In addition, the results of comsol are validated for the Mettler model of slender beams against an in-house constructed finite-element discretization scheme, the convergence of which is assessed for increasing number of finite elements.
Analysis of Shoe Friction During Sliding Against Floor Material: Role of Fluid Contaminant
Authors: Moore Caitlin T. , Menezes Pradeep L. , Lovell Michael R. , Beschorner Kurt E.
Published: September 2012

Understanding the tribological interactions between shoe and floor materials is important in order to enhance shoe and floor design and to prevent slip and fall accidents during walking. In the present investigation, experiments were conducted using a custom developed pin-on-disk type tribometer to understand the influence of boundary and hydrodynamic properties on the shoe-floor materials’ coefficient of friction. Specifically, polyurethane shoe material was slid against vinyl floor material in the presence of varying lubricants (i.e., water, detergent, three diluted glycerol concentrations, and canola oil). The experiments were conducted for a range of biologically relevant sliding velocities from 0.05 m sec−1 to 1.0 m sec−1 at a contact pressure of 266.1 kPa under ambient conditions. The fluid chemical composition appeared to affect the boundary friction coefficient with longer-chain molecules resulting in a decreased coefficient of friction. As fluid viscosity increased, the rate of coefficient of friction decay increased with respect to increasing fluid entrainment velocity, suggesting less material contact and increased film thickness. The nondimensional film thickness under all conditions was calculated and the nondimensional film thickness consistently increased with increased viscosity and speed. Additionally, the effect of functionally achievable variations in polyurethane shoe roughness on the coefficient of friction was examined and found to have no statistically significant effect on boundary or hydrodynamic contributions to the coefficient of friction.
Numerical Analysis of Laser-Textured Piston-Rings in the Hydrodynamic Lubrication Regime
Authors: Gadeschi Gonzalo Brito , Backhaus Katja , Knoll Gunther
Published: September 2012

In this work, the performance of barrel-shaped laser-textured piston rings is numerically investigated. The surface texture, parameterized by the dimple density, dimple depth, and dimple distribution pattern, is optimized to minimize the friction coefficient for piston rings of variable curvature. We consider fully textured as well as partially textured piston rings with two different dimple distributions patterns: a central dimple distribution, and a distribution along the piston ring edges. Finally, the sensitivity of the optimal surface parameters to the piston ring curvature is assessed.
A New Approach for Including Cage Flexibility in Dynamic Bearing Models by Using Combined Explicit Finite and Discrete Element Methods
Authors: Ashtekar Ankur , Sadeghi Farshid
Published: September 2012

In this investigation, a new approach was developed to study the influence of cage flexibility on the dynamics of inner and outer races and balls in a bearing. A 3D explicit finite element model (EFEM) of the cage was developed and combined with an existing discrete element dynamic bearing model (DBM) with six degrees of freedom. The EFEM was used to determine the cage dynamics, deformation, and resulting stresses in a ball bearing under various operating conditions. A novel algorithm was developed to determine the contact forces between the rigid balls and the flexible (deformable) cage. In this new flexible cage dynamic bearing model, the discrete and finite element models interact at each time step to determine the position, velocity, acceleration, and forces of all bearing components. The combined model was applied to investigate the influence of cage flexibility on ball-cage interactions and the resulting ball motion, cage whirl, and the effects of shaft misalignment. The model demonstrates that cage flexibility (deflection) has a significant influence on the ball-cage interaction. The results from this investigation demonstrate that the magnitude of ball-cage impacts and the ball sliding reduced in the presence of a flexible cage; however, as expected, the cage overall motion and angular velocity were largely unaffected by the cage flexibility. During high-speed operation, centrifugal forces contribute substantially to the total cage deformation and resulting stresses. When shaft misalignment is considered, stress cycles are experienced in the bridge and rail sections of the cage where fatigue failures have been observed in practice and in experimental studies.
Load Performance of Large-Scale Rolling Bearings With Supporting Structure in Wind Turbines
Authors: Chen Guanci , Wen Jianmin
Published: September 2012

The stiffness of rolling bearings and their supporting structure in wind turbines is very low because of their large dimensions. Accurate predictions of the deformations of bearing elements and their flexible supports are difficult. In this paper, the finite element method (FEM) is employed to determine the mechanical behaviors of the large-scale bearings. Traction springs are used to model the contact between raceways and rolling elements. A pitch bearing supports the whole hub, the partial hub and the rigid outer ring under loads is studied. Results show that a comprehensive model representing the surrounding structure is necessary for an accurate assessment of the actual loading conditions of large-scale WTG pitch bearings. The load is shared well between the two bearing rows by appropriately decreasing the stiffness of the plane rib.
Influence of Fabrication and Interference-Fit Techniques on Tensile and Fatigue Properties of Pin-Loaded Glass Fiber Reinforced Plastics Composites
Authors: Kim Sang-Young , Hennigan Daniel J. , Kim Dave (Dae-Wook)
Published: September 2012

This paper aims to investigate the effect of fabrication processes on fatigue life enhancement of interference-fit pin-loaded glass fiber reinforced plastics (GFRP) composites. In this experimental study, three GFRP composite fabrication processes are used: hand lay-up (HL), vacuum infusion (VI), and hybrid (hand lay-up + vacuum infusion) processes. Stainless steel pins with interference fits ranging from 0% to 1% are inserted into the GFRP samples. The quasi-static and fatigue properties of the pin-loaded composites with interference fit (0.6% and 1%) are then compared to samples with transition-fit (0% of interference fit). Even with possible local damage on the joints, interference fit does not degrade the performance of the composite joints under quasi-static loading, especially when kept under 1% of interference fit. However, fatigue life is highly related to the fabrication processes. Vacuum infusion processed GFRP samples show most visible fatigue life improvement due to interference fit, while hand lay-up or hybrid samples have moderate improvement. Fractography and failure mode of each sample are examined using microscopes.
Numerical Analysis of the Grasp Configuration of a Planar 3-DOF Linkage-Driven Underactuated Finger
Authors: Khakpour Hamed , Birglen Lionel
Published: September 2012

This paper proposes a novel method to investigate the grasp sequence of an underactuated (a.k.a. adaptive) finger with three degrees of freedom but only one actuator and find its final configuration. This method considers the magnitude and the sign of the torques generated on the phalanges of the finger through the contact points. By using these torques as indices, the algorithm calculates the values of the joint angles during the grasping sequence until the finger reaches its final configuration. To illustrate the effectiveness of this method a class of a 3-DOF adaptive finger is chosen and analyzed and then, using the proposed methodology, its grasp configuration is calculated when grasping different fixed objects. Finally, simulations are repeated using a dynamic simulation package and the obtained results are compared to the proposed method. The results show that the method can properly estimate the final configuration of the grasp.
New oxygen radical source using selective sputtering of oxygen atoms for high rate deposition of TiO2 films
Authors: Yasuda Yoji , Lei Hao , Hoshi Yoichi
Published: September 2012

We have developed a new oxygen radical source based on the reactive sputtering phenomena of a titanium target for high rate deposition of TiO2 films. In this oxygen radical source, oxygen radicals are mainly produced by two mechanisms: selective sputter-emission of oxygen atoms from the target surface covered with a titanium oxide layer, and production of high-density oxygen plasma in the space near the magnetron-sputtering cathode. Compared with molecular oxygen ions, the amount of atomic oxygen radicals increased significantly with an increase in discharge current so that atomic oxygen radicals were mainly produced by this radical source. It should be noted that oxygen atoms were selectively sputtered from the target surface, and titanium atoms sputter-emitted from the target cathode were negligibly small. The amount of oxygen radicals supplied from this radical source increased linearly with increasing discharge current, and oxygen radicals of 1 × 1015 atoms/s/cm2 were supplied to the substrate surface at a discharge current of 1.2 A. We conclude that our newly developed oxygen radical source can be a good tool to achieve high rate deposition and to control the structure of TiO2 films for many industrial design applications.
Fabrication of digital planar holograms into high refractive index waveguide core for spectroscopy-on-chip applications
Authors: Calò Cosimo , Lacatena Valeria , Dhuey Scott D. , Cabrini Stefano , Babin Sergey , Peroz Christophe , Koshelev Alexander , Ivonin Igor , Goltsov Alexander , Yankov Vladimir
Published: September 2012

A novel class of large-bandwidth wavelength demultiplexers, based on digital planar holography for on-chip spectroscopy applications, was fabricated in high refractive index contrast SiO2/Si3N4 planar waveguides. The devices consist of computer-generated digital planar holograms (DPHs) encoding the transfer function of the demultiplexers, engraved on the core layer of the optical waveguide. An optimized fabrication process has been developed to produce DPHs with an etching depth as low as 10 nm in Si3N4. The first spectrometer devices exhibit overall bandwidths as large as 98 nm and spectral channel spacings down to 0.3 nm/channel.
A novel conformity index for intensity modulated radiation therapy plan evaluation
Authors: Cheung Fion W. K. , Law Maria Y. Y.
Published: September 2012

Purpose:

Intensity modulated radiation therapy (IMRT) has gained popularity in the treatment of cancers. Manual evaluation of IMRT plans for head‐and‐neck cancers has been especially challenging necessitating efficient and objective assessment tools. In this work, the authors address this issue by developing a personalized conformity index (CI) for comparison of IMRT plans for head‐and‐neck cancers and evaluating its plan quality discerning power in comparison with other widely used CIs.

Methods:

A two‐dimensional CI with dose and distance incorporated (CIDD) was developed using the MATLAB program language, to quantify the planning target volume (PTV) coverage. Valuable information contained in the digital imaging and communication in medicine (DICOM) RT objects were harvested for computation of each of the CIDD components. Apart from the dose penalty factor, a distance‐based exponential function was employed by varying the penalty weight associated with the location of cold spots within the PTV. With the goal of deriving a customized penalty factor, the distances between individual pixel and its nearest PTV boundary was found. Using the exponential function, the impact of distance penalty was substantially larger for cold spots closer to the PTV centroid but petered out quickly wherever they were situated in the vicinity of PTV border. In order to evaluate the CIDD scoring system, three CT image data sets of nasopharyngeal carcinoma (NPC) patients were collected. Ten IMRT plans with degrading qualities were generated from each dataset and were ranked based on CIDD and other existing indices. The coefficient of variance was calculated for each dataset to compare the degree of variation.

Results:

The CIDD scoring system that considered spatial importance of each voxel within the PTV was successfully developed. The results demonstrated that the CIDD including four discrete factors could provide accurate rankings of plan quality by examining the relative importance of each cold spot within the PTVs. Apart from the dose penalty factor, a distance‐based exponential function was employed taking the specific tumor geometry into account. Compared with other commonly used CIs, the CIDD resulted in the largest coefficient of variance among the ten IMRT plans for each dataset, indicating that its discerning power was the best among the CIs being compared.

Conclusions:

The CIDD scoring system was successfully developed to incorporate patient‐specific spatial dose information and provide a geometry‐based physical index for comparison of IMRT plans for head‐and‐neck cancers. By taking individual tumor geometry into account, the superiority of CIDD in plan discerning power was demonstrated. The use of CIDD could provide an effective means of benchmarking performance, reducing treatment plan variability, and advancing the quality of current IMRT planning.
FAM123A Binds to Microtubules and Inhibits the Guanine Nucleotide Exchange Factor ARHGEF2 to Decrease Actomyosin Contractility
Authors: Siesser Priscila F. , Motolese Marta , Walker Matthew P. , Goldfarb Dennis , Gewain Kelly , Yan Feng , Kulikauskas Rima M. , Chien Andy J. , Wordeman Linda , Major Michael B.
Published: September 2012

Unlike related proteins, FAM123A interacts with microtubule-associated proteins and alters microtubule dynamics.
Guanylyl Cyclases A and B Are Asymmetric Dimers That Are Allosterically Activated by ATP Binding to the Catalytic Domain
Authors: Robinson Jerid W. , Potter Lincoln R.
Published: September 2012

An ATP-binding allosteric site could be pharmacologically targeted to alter the activity of membrane guanylyl cyclases.
Skin Specifics
Authors: Mueller Kristen L.
Published: September 2012

The skin microbiota play a selective role in modulating immunity in the skin of mice.
A Double Escapee
Authors: Mueller Kristen L.
Published: September 2012

A region of ribosomal RNA that confers antibiotic resistance is also recognized by mouse innate immune receptors.
Positive Selection
Authors: Wong Wei
Published: September 2012

Voltage-gated sodium channels enhance Ca
2+
influx in response to nonself ligands and promote the development of CD4
+
T cells.
Delivering a Proangiogenic Message in a MicroRNA-Containing Vesicle
Authors: Andrianantoandro Ernesto
Published: September 2012

MicroRNAs released by tumor cells activate the JAK-STAT pathway in endothelial cells, leading to migration and angiogenesis.
Linking Stress and Apoptosis to Impaired Mitochondrial Fusion
Authors: Andrianantoandro Ernesto
Published: September 2012

Stress induces JNK phosphorylation of a mitochondrial fusion protein, leading to its degradation, mitochondrial fragmentation, and apoptosis.