bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Model to Calculate Friction Coefficients and Shear Stresses in Thermal Drilling
Authors: Qu Jun , Blau Peter J.
Published: May 2008

A new analytical model for thermal drilling (also known as friction drilling) has been developed. The model distinguishes itself from recent work of other investigators by improving on two aspects: (1) the new model defines material plastic flow in terms of the yield in shear rather than the yield in compression, and (2) it uses a single, variable friction coefficient instead of assuming two unrelated friction coefficients in fixed values. The time dependence of the shear stress and friction coefficient at the hole walls, which cannot be measured directly in thermal drilling, can be calculated using this model from experimentally measured values of the instantaneous thrust force and torque. Good matches between the calculated shear strengths and the handbook values for thermally drilling low carbon steel confirm the model’s validity.
Plastic Deformation in Silicon Crystal Induced by Heat-Assisted Laser Shock Peening
Authors: Cheng Gary J. , Cai M. , Pirzada Daniel , Guinel Maxime J.-F. , Norton M. Grant
Published: May 2008

The response of solid to shock compression has been an interesting topic for more than a century. The present work is the first attempt to experimentally show that plastic deformation can be generated in brittle materials by a heat-assisted laser shock peening process, using silicon crystal as a sample material. Strong dislocation activity and large compressive residual stress are induced by this process. The dislocation structure is characterized with transmission electron microscopy and electron backscattered diffraction. The residual stress is measured using Raman scattering. This work presents a fundamental base for the application of laser shock peening in brittle materials to generate large compressive residual stress and plastic deformation for better mechanical properties, such as fatigue life and fracture toughness.
Virtual Five-Axis Flank Milling of Jet Engine Impellers—Part I: Mechanics of Five-Axis Flank Milling
Authors: Ferry W. B. , Altintas Y.
Published: May 2008

This work is the first of a two part paper on cutting force prediction and feed optimization for the five-axis flank milling of jet engine impellers. In Part I, a mathematical model for predicting cutting forces is presented for five-axis machining with tapered, helical, ball-end mills with variable pitch and serrated flutes. The cutter is divided axially into a number of differential elements, each with its own feed-coordinate system due to five-axis motion. At each element, the total velocity due to translation and angular motion is split into horizontal and vertical feed components, which are used to calculate total chip thickness along the cutting edge. The cutting forces for each element are calculated by transforming friction angle, shear stress, and shear angle from an orthogonal cutting database to the oblique cutting plane. The distributed cutting load is digitally summed to obtain the total forces acting on the cutter and blade. The model can be used for general five-axis flank milling processes, and supports a variety of cutting tools. Predicted cutting forces are shown to be in reasonable agreement with those collected during a roughing operation on a prototype integrally bladed rotor.
Controller Design Procedure for Two-Mass Systems With Single Flexible Mode
Authors: Shin Young Joo , Meckl Peter H.
Published: May 2008

Many manufacturing machines must execute motions as quickly as possible to achieve profitable high-volume production. Most of them exhibit some flexibility, which makes the settling time longer and controller design difficult. This paper develops a control strategy that combines feedforward and feedback control with command shaping for systems with collocated actuator and sensor. First, a feedback controller is designed to increase damping and eliminate steady-state error. Next, an appropriate reference profile is generated using command-shaping techniques to ensure fast point-to-point motions with minimum residual vibration. Finally, a feedforward controller is designed to speed up the transient response. The proposed proportional-integral-derivative (PID) controller design ensures that two important resonant frequencies nearly match, making the design of the input commands much simpler. The resulting control strategy is successfully demonstrated for a generic dimensionless system that incorporates some modeling errors to assess robustness.
Transformer Eddy Current Dampers for the Vibration Control
Authors: Tonoli Andrea , Amati Nicola , Silvagni Mario
Published: May 2008

Eddy current dampers are promising for the passive and semiactive vibration control of mechanical structures. Among them, the “motional” types are based on Lorentz forces between a moving conductor and a stationary magnetic field. On the contrary, “transformer” ones exploit electromagnetic forces varying the reluctance of the magnetic circuit due to the motion of a part of the damper. Considering the simplicity of the layout, transformer configurations seem to be very promising as alternative to traditional rubber or squeeze film dampers to control the lateral vibration of rotating machines. The aim of the present paper is to investigate the dynamic behavior of transformer eddy current dampers integrated in a mechanical structure. The electromechanical system is modeled using the Lagrange approach in terms of the magnetic flux linkages in the electromagnets. The mathematical models have been experimentally validated using two test benches with different layouts and geometrical characteristics of the magnetic circuit. The modeling approach allows to propose a design procedure of this type of damper.
A Polynomial-Based Linear Mapping Strategy for Feedforward Compensation of Hysteresis in Piezoelectric Actuators
Authors: Bashash Saeid , Jalili Nader
Published: May 2008

A set of memory-based properties is employed in this paper for modeling multiple-path hysteresis response of piezoelectric actuators. These properties, namely, targeting turning points, curve alignment, and wiping-out effect, are applied in a linear mapping strategy to develop a mathematical framework for modeling the hysteresis phenomenon. More specifically, the locations of turning points are detected and recorded for the prediction of future hysteresis trajectory. An internal trajectory is assumed to follow a multiple-segmented path via a continuous connection of several curves passing through every two consequent turning points. These curves adopt their shapes via a linear mapping strategy from the reference hysteresis curves with polynomial configurations. Experimental implementation of the proposed method demonstrates slight improvement over the widely used Prandtl–Ishlinskii hysteresis operator. However, to maintain the level of precision during the operation, a sufficient number of memory units must be included to record the turning points. Otherwise, in the event of memory saturation, two memory-allocation modes, namely, “open” and “closed” strategies, can be implemented. It is shown that the closed memory-allocation strategy demonstrates better performance by keeping the most important target points. The proposed modeling framework is adopted in an inverse model-based control scheme for feedforward compensation of hysteresis nonlinearity. The controller is experimentally implemented on a three-dimensional nanopositioning stage for surface topography tracking, a problem typically encountered in scanning probe microscopy applications.
Robust Piecewise-Linear State Observers for Flexible Link Mechanisms
Authors: Caracciolo Roberto , Richiedei Dario , Trevisani Alberto
Published: May 2008

This paper tackles the problem of designing state observers for flexible link mechanisms: An investigation is made on the possibility of employing observers making use of suitable piecewise-linear truncated dynamics models. A general and novel approach is proposed, which provides an objective way of synthesizing observers preventing the instability that may arise from using reduced-order linearized models. The approach leads to the identification of the regions of the domain of the state variables where the linear approximations of the nonlinear model can be considered acceptable. To this purpose, first of all, the stability of the equilibrium points of the closed-loop system is assessed by applying the eigenvalue analysis to appropriate piecewise-linear models. Admittedly, the dynamics of such a closed-loop system is affected by the perturbation of the poles caused by spillover and by the discrepancies between the linearized models of the plant and the one of the observer. Additionally, when nodal elastic displacements and velocities are not bounded in the infinitesimal neighborhoods of the equilibrium points, the difference between the nonlinear model and the locally linearized one is expressed in terms of unstructured uncertainty and stability is assessed through H∞ robust analysis. The method is demonstrated by applying it to a closed-chain flexible link mechanism.
Dry etching of SiGe alloys by xenon difluoride
Authors: Xuan G. , Adam T. N. , Lv P.-C. , Sustersic N. , Coppinger M. J. , Kolodzey J. , Suehle J. , Fitzgerald E.
Published: May 2008

Dry etching with xenon difluoride (XeF2) is a well-known process for the isotropic removal of silicon. The etching of silicon-germanium alloys with XeF2, however, has not yet been investigated. Here, the XeF2 dry etching of SiGe alloys was characterized versus composition and XeF2 partial pressures. It was found that the etch rates showed a strong dependence on Ge content of the etched materials. The roughness of the etched surfaces was also investigated. This study provides etch rates versus process conditions and etched surface roughness, which are useful for accurately fabricating SiGe-based structures and devices.
Preparation of TiO2 thin films on the inner surface of a quartz tube using atmospheric-pressure microplasma
Authors: Yoshiki Hiroyuki , Saito Taku
Published: May 2008

Titanium dioxide (TiO2) thin films were prepared on the inner surface of a quartz tube, with inner and outer diameters of 1 and 3mm, respectively, using plasma-enhanced chemical vapor deposition with titanium tetraisopropoxide and oxygen (O2) as reactants and helium as the carrier gas at atmospheric pressure. A microplasma was generated inside the tube by rf (13.56MHz) excitation using externally attached parallel-plate electrodes. The characteristics of the deposited films were examined by scanning electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction. A typical as-deposited film had an amorphous structure with a smooth surface and was transparent. With increasing O2 concentration in the plasma gas phase, the deposited film surface was covered with a large number of TiO2 nanoparticles. However, the deposited films were a mixture of TiO2 and amorphous carbon and showed rough surface in the absence of O2 in the source gas. The effects of the O2 concentration in the plasma gas on the characteristics of the deposited TiO2 films are discussed on the basis of the analysis of the gas species generated in the plasma using optical emission spectroscopy.
Mechanical properties of amorphous hydrogenated carbon films fabricated on polyethylene terephthalate foils by plasma immersion ion implantation and deposition
Authors: Li Jing , Tian Xiubo , Yang Shiqin , Chu Paul K. , Fu Ricky K. Y.
Published: May 2008

Amorphous hydrogenated carbon (a-C:H) films have been deposited on polyethylene terephthalate by plasma immersion ion implantation and deposition. The influence of deposition parameters such as gas pressure, bias voltage, and nitrogen incorporation on the mechanical properties of the a-C:H films are investigated. X-ray photoelectron spectroscopy reveals that the ratio of sp3 to sp2 is 0.24 indicating that the film is mainly composed of graphitelike carbon. Nanoindentation tests disclose enhanced surface hardness of ∼6GPa. The friction coefficient of the film deposited at higher gas pressure, for instance, 2.0Pa, is lower than that of the film deposited at a lower pressure such as 0.5Pa. The films deposited using a low bias voltage tend to fail easily in the friction tests and nitrogen incorporation into the a-C:H films decreases the friction coefficient. Mechanical folding tests show that deformation failure is worse on a thinner a-C:H film.
Study of tungsten oxidation in O2∕H2∕N2 downstream plasma
Authors: Xu Songlin , Diao Li
Published: May 2008

The surface oxidation of tungsten is a serious issue in plasma processing of advanced integrated-circuit devices where tungsten is being used as a gate electrode. In this article, we study tungsten oxidation in O2∕H2∕N2 downstream plasma at a temperature ⩽300°C. The results show that oxidation occurs rapidly in O2 downstream plasma to form stable WO3. However, oxidation can be reduced effectively by adding H2 and totally suppressed when H2 concentration in the gas feed reaches a certain low level at which the plasma is still oxygen dominant. Tungsten oxidation increases significantly with sample temperature and exposure time in O2 downstream plasma. However, H2 addition reduces both temperature and time dependences due to the coexistence and competition of oxidation and reduction processes. When N2 is also added, the efficiency of H2 in O2 downstream plasma in controlling tungsten oxidation is lowered. The findings may provide effective approaches to various applications of selective oxidation over tungsten, such as photoresist stripping and polysilicon oxidation on tungsten gate structures.
Experimental study of spatial nonuniformities in 100MHz capacitively coupled plasma using optical probe
Authors: Volynets V. N. , Ushakov A. G. , Sung D. , Tolmachev Y. N. , Pashkovsky V. G. , Lee J. B. , Kwon T. Y. , Jeong K. S.
Published: May 2008

Plasma spatial nonuniformities in the 100MHz rf driven capacitively coupled reactor used for reactive ion etching of 300mm substrates were experimentally studied using a linear scanning optical emission spectroscopy probe. Radial profiles of plasma emission intensity were measured both in argon and fluorocarbon-containing gas mixtures in the pressure interval of 10–80mTorr and the rf power range of 500–1250W. It was demonstrated that the plasma emission profiles strongly depend on the working gas composition and pressure. The profiles have a bell-like shape at pressures about 10mTorr for all gases. As the pressure increases, the profile shape becomes more complex with the central and peripheral peaks, and the amplitudes of the peaks strongly depend on the working gas composition. It is suggested that the emission profiles show plasma spatial nonuniformities that can influence the etching rate profiles obtained with such systems. According to the existing theoretical models, the most probable reasons for these plasma nonuniformities are charged particle radial diffusion at low pressures (about 10mTorr), as well as the standing wave and skin and edge effects at higher pressures. Using the experimental emission profiles, the working conditions have been found that allow one to achieve the most uniform plasma for discharges in argon and fluorocarbon-containing gas mixtures.
Tungsten atomic layer deposition on cobalt nanoparticles
Authors: Wilson C. A. , Goldstein D. N. , McCormick J. A. , Weimer A. W. , George S. M.
Published: May 2008

Tungsten (W) atomic layer deposition (ALD) was performed on cobalt (Co) nanoparticles using WF6 and Si2H6 as reactants. A variety of techniques were then applied to analyze both the Co nanoparticles and flat Co substrates after W ALD. Analysis of the W ALD-coated Co nanoparticles is complicated because a CoO layer may exist on the Co nanoparticles and a WO3 layer may be present on the W ALD coating. LECO measurements quantified the oxygen weight percent in the W ALD-coated Co nanoparticles. The oxygen weight percent decreased with increasing number of W ALD AB cycles. To determine the location of this oxygen, x-ray reflectivity (XRR) investigations measured the WO3 film thickness on flat W ALD films. The XRR measurements yielded a WO3 film thickness on flat W ALD films of ∼20Å. X-ray photoelectron spectroscopy (XPS) studies also quantified the relative oxygen abundance at the W∕Co interface for W ALD on flat Co films. The XPS measurements revealed that nearly all the oxygen was in the WO3 layer on the W ALD film. Only an immeasurably small amount of oxygen was bonded as CoO at the W∕Co interface. To determine the thickness of W ALD film on the Co nanoparticle, surface profilometry of W ALD on flat Co substrates measured a W ALD growth rate of 3.9Å per AB cycle. A geometric model was then constructed to incorporate the information from all the measurements on Co nanoparticles and flat Co substrates. Excellent agreement between the geometrical model and the oxygen weight percent versus the number of W ALD cycles was obtained when the CoO thickness was negligible and the WO3 thickness on the W ALD layer on the Co nanoparticles was 28.5Å. This agreement indicates that the details of ALD on nanoparticles can be unraveled by a concert of techniques even when interfacial layers can form due to the high reactivity of nanoparticles. The W ALD-coated Co nanoparticles may be useful in fabricating WC–Co hardmetals with enhanced mechanical properties.
Plasma-assisted atomic layer deposition of Ta2O5 from alkylamide precursor and remote O2 plasma
Authors: Heil S. B. S. , Roozeboom F. , van de Sanden M. C. M. , Kessels W. M. M.
Published: May 2008

Tantalum oxide (Ta2O5) films were synthesized by plasma-assisted atomic layer deposition from pentakis(dimethylamino)tantalum (Ta[N(CH3)2]5), precursor and remote O2 plasma as oxidation source. Film growth was monitored in situ by spectroscopic ellipsometry, and film properties were investigated for deposition temperatures between 100 and 225°C. Saturated precursor dosing conditions and plasma exposure times were identified and growth rates ranging from 0.8Å∕cycle at 225°Cto0.87Å∕cycle at 100°C were obtained. The deposited films were found to be stoichiometric (Ta:O=2:5). Moreover, no N incorporation was detected, and the C content was below the detection limit of the Rutherford backscattering measurement (<2at.%) for all films studied. The mass density of the films, ranging from 7.8gcm−3 at 100°Cto8.1gcm−3 at 225°C, was found to be close to the bulk Ta2O5 density. The deviation could partly be accounted for by the amount of H detected with elastic recoil detection analysis, varying from 2at.% at 225°Cto4.6at.% at 100°C. X-ray diffraction revealed that all films were amorphous, independent of deposition temperature. The reaction mechanisms, in particular, during the plasma step, were investigated by using quadrupole mass spectrometry and optical emission spectroscopy. During the plasma step, combustion products such as CO, CO2, and H2O were detected. This indicates that combustionlike processes occur, in which the alkylamide N(CH3)2 ligands are oxidized by the O radicals generated in the plasma. Additionally, the presence of excited CN* molecules in the plasma was observed in the plasma emission.
GRAVITATIONAL LENSING BY WORMHOLES
Authors: DEY TUSHAR KANTI , SEN SURAJIT
Published: May 2008

We have investigated the gravitational lensing by two wormholes, viz., Janis–Newman–Winnicour (JNW) wormhole and Ellis wormhole. The deflection angles in the strong field limit are calculated and various lens parameters of two wormholes are compared. It is shown that the JNW wormhole exhibits the relativistic images, while the Ellis wormhole does not have any relativistic image due to the absence of its photon sphere.
(NON)ETERNAL BRANE INFLATION
Authors: SARANGI SASWAT
Published: May 2008

The random walk type eternal inflation in brane inflationary scenarios is reviewed. Unlike inflation in field theory with standard kinetic term, the DBI nature of the action describing the brane motion introduces extra constraints on eternal inflation. Constraints also appear due to the finite size of extra dimensions. In the context of false vacuum eternal inflation, we note that the Coleman–De Luccia instanton for a D-brane receives corrections due to the DBI nature of the action. This can enhance vacuum decay for a fine-tuned region of parameter space. Finally, some recent work on the stochastic Langevin description of the D-brane motion is reviewed. This leads to a modification to the Hawking–Moss probability distribution.
EXISTENCE OF GLOBAL WEAK SOLUTIONS TO DUMBBELL MODELS FOR DILUTE POLYMERS WITH MICROSCOPIC CUT-OFF
Authors: BARRETT JOHN W. , SÜLI ENDRE
Published: May 2008

We study the existence of global-in-time weak solutions to a coupled microscopic–macroscopic bead-spring model with microscopic cut-off, which arises from the kinetic theory of dilute solutions of polymeric liquids with noninteracting polymer chains. The model consists of the unsteady incompressible Navier–Stokes equations in a bounded domain Ω ⊂ ℝd, d = 2 or 3, for the velocity and the pressure of the fluid, with an elastic extra-stress tensor as the right-hand side in the momentum equation. The extra-stress tensor stems from the random movement of the polymer chains and is defined through the associated probability density function ψ that satisfies a Fokker–Planck-type parabolic equation, a crucial feature of which is the presence of a center-of-mass diffusion term and a cut-off function βL(ψ) = min (ψ,L) in the drag term, where L ≫ 1. We establish the existence of global-in-time weak solutions to the model for a general class of spring-force potentials including, in particular, the widely used finitely extensible nonlinear elastic potential. A key ingredient of the argument is a special testing procedure in the weak formulation of the Fokker–Planck equation, based on the convex entropy function [Formula: see text]. In the case of a corotational drag term, passage to the limit as L → ∞ recovers the Navier–Stokes–Fokker–Planck model with centre-of-mass diffusion, without cut-off.
ESTIMATION OF OPTIMAL PORTFOLIO WEIGHTS
Authors: OKHRIN YAREMA , SCHMID WOLFGANG
Published: May 2008

The paper discusses finite sample properties of optimal portfolio weights, estimated expected portfolio return, and portfolio variance. The first estimator assumes the asset returns to be independent, while the second takes them to be predictable using a linear regression model. The third and the fourth approaches are based on a shrinkage technique and a Bayesian methodology, respectively. In the first two cases, we establish the moments of the weights and the portfolio returns. A consistent estimator of the shrinkage parameter for the third estimator is then derived. The advantages of the shrinkage approach are assessed in an empirical study.
FOREIGN EXCHANGE OPTIONS UNDER STOCHASTIC VOLATILITY AND STOCHASTIC INTEREST RATES
Authors: AHLIP REHEZ
Published: May 2008

In this paper, we present a stochastic volatility model with stochastic interest rates in a Foreign Exchange (FX) setting. The instantaneous volatility follows a mean-reverting Ornstein–Uhlenbeck process and is correlated with the exchange rate. The domestic and foreign interest rates are modeled by mean-reverting Ornstein–Uhlenbeck processes. The main result is an analytic formula for the price of a European call on the exchange rate. It is derived using martingale methods in arbitrage pricing of contingent claims and Fourier inversion techniques.
Neuronal Correlates of Post-Error Slowing in the Rat Dorsomedial Prefrontal Cortex
Authors: Narayanan Nandakumar S. , Laubach Mark
Published: May 2008

Rats with impaired function in dorsomedial regions of the prefrontal cortex (dmPFC) are unable to maintain a behavioral response over a delay period. Here we report that neurons in this cortical region are prominently modulated after errors in a tone-cued, simple reaction time task and that inactivation of dmPFC attenuates a slowing of reaction times that is observed following errors. Using methods for chronic single-unit recording, we found that approximately one-third of dmPFC neurons were modulated after errors, and 28% of these neurons had increased posterror firing that persisted into the delay period of the following trial. In contrast to dmPFC, no such neurons were found in motor cortex. Our results implicate the dorsomedial prefrontal cortex in a form of retrospective working memory that improves task performance following errors.
Quality of Life after Radical Prostatectomy
Authors: Liatsikos Evangelos N. , Assimakopoulos Kostantinos , Stolzenburg Jens-Uwe
Published: May 2008

Introduction: Radical prostatectomy is a standard approach to the management of prostate cancer. As the oncological outcome has improved, focus has drawn to the postoperative amelioration of health-related quality of life (HRQOL). Materials and Methods: The instruments that have already been used, or may be used, in assessing the HRQOL postoperatively in men with prostate cancer are presented. Results: Urinary and sexual dysfunction as well as fecal incontinence form the three possible major complications after surgery which affect the patient’s quality of life. Meticulous counseling regarding the potential morbidity associated with the operation that may affect the patient’s quality of life should be made before the patient gives his informed consent. Conclusions: Questionnaires only partially help to identify patients with dysfunction, especially sexual and bowel dysfunction, and careful patient counseling with their partners present is the best way to evaluate the presence of dysfunction pre- or postoperatively.
Histopathologically Proven Prevention of Post-Prostatectomy Cavernosal Fibrosis with Sildenafil
Authors: Iacono Fabrizio , Prezioso Domenico , Somma Pasquale , Chierchia Stefania , Galasso Raffaele , Micheli Pietro
Published: May 2008

Aim: To evaluate whether a dose of 50 mg preserved the architecture of the corpora cavernosa biopsy in man. Methods: 21 patients (54–70 years old) who underwent radical prostatectomy for prostate cancer were treated with sildenafil citrate (50 mg, 3 times a week for 2 months) soon after surgery. They underwent cavernous biopsy before surgery and after 2 months of sildenafil treatment. Biopsy tissues were fixed in formalin, stained with Masson’s trichrome method, and evaluated with the Eureka Interface system with a per-area analysis, and elastic fibers were counted on 10–12 fields (×400) of five serial sections. Results: Two months after surgery the percent of connective tissue in cavernosa samples in all patients did not differ from that before surgery, being between 30 and 40% in the per-area analysis. Similarly, the elastic fiber count did not differ significantly before and after surgery. Conclusions: Sildenafil prevented the progression of fibrosis in prostatectomized patients. Its efficacy seems to result from an antiproliferative effect exerted on fibroblasts.
Comparison of Lidocaine Suppositories and Periprostatic Nerve Block during Transrectal Prostate Biopsy
Authors: Szlauer Roman , Götschl Robert , Gnad Andrea , Meissner Phillip , Paras Ljiljana , Schmeller Nikolaus T. , Fink Klaus G.
Published: May 2008

The aim of this randomized prospective and partially double-blind study was to evaluate the efficacy of transrectal lidocaine applied as suppositories in comparison to periprostatic infiltration as methods of reducing pain during transrectal prostate biopsy. 100 patients were randomized to four groups and received either a suppository containing 60 mg of lidocaine 2 h before biopsy, a 120-mg lidocaine suppository 1 h before biopsy, a 120-mg lidocaine suppository 2 h before biopsy, or they were anaesthetized with a periprostatic infiltration of 5 ml 2% lidocaine. In all patients the same 10-core transrectal biopsy technique was performed. Pain was evaluated using a visual pain scale ranging from 0 to 10 points. The mean pain score in the 60-mg (2 h), 120-mg (1 h), and 120-mg (2 h) lidocaine suppository groups was 3.63, 3.56, and 3.58 respectively. The mean pain score of patients receiving periprostatic infiltration was 1.80. No patient showed vegetative symptoms like sweating or hypotonia. No patient had severe pain. Eight of the 9 patients with no pain were in the periprostatic injection group. Thus, all lidocaine suppositories showed a good analgesic effect although a significantly better pain reduction was achieved by periprostatic lidocaine infiltration.
Internet Survey of Management Trends of Urethral Strictures
Authors: Rapp David E. , Chanduri Krishi , Infusino Giovanni , Hoda Zahid A. , Orvieto Marcelo A. , Elliott Sean P. , Alsikafi Nejd F.
Published: May 2008

Objectives: The management of urethral stricture is often complex and the decision to proceed to urethroplasty may be difficult. A variety of factors are used by urologists to help guide this decision. We sought to conduct a survey to define current management trends and referral patterns in the treatment of urethral stricture disease. Methods: An internet survey was conducted using the email directory for the AUA North Central Section. Survey design focused on urologist demographics and practice type, practice trends for treating urethral strictures, and referral patterns. Results were analyzed to assess for demographic parameters influencing management and referral trends. Results: Responses were received from 84/600 (14%) urologists. Despite 95% of respondents reporting the recent treatment of urethral stricture, the majority of urologists reported performing no urethroplasties within the same time period. Complicated repairs (posterior, buccal) were performed by only a few of the respondents. A variety of factors were used by urologists to help decide at what point urethroplasty should be pursued. However, the importance of these factors varied significantly. Conclusions: Our data suggest that the treatment algorithm for urethral strictures is complex and varies considerably between urologists. The decision to perform urethroplasty may be particularly difficult. Finally, patient referral appears to play a significant role in stricture management. Treatment guidelines based on objective data are needed.
The Hemostatic Properties of Transurethral Plasmakinetic Resection of the Prostate: Comparison with Conventional Resectoscope in an ex vivo Study
Authors: Qu Lijun , Wang Xinghuan , Huang Xing , Zhang Yanqing , Zeng Xiao
Published: May 2008

Aim: To compare the hemostatic properties of transurethral plasmakinetic resection of the prostate (PKRP) and standard transurethral resection of the prostate (TURP) ex vivo, as perioperative bleeding is still regarded as one of the major complications of transurethral prostatectomy. Materials and Methods: Isolated normal saline (NS)-perfused porcine kidneys were used to determine the hemostatic efficacy of PKRP and TURP. The perfusion fluid loss was semiquantitatively measured in relation to tissue ablation for the two techniques and specimens were evaluated histologically. Results: The PKRP group had a significantly smaller loss of NS than the TURP group (4.16 ± 1.25 and 6.39 ± 1.05 g/min, respectively, p < 0.01). Compared with the measurements with TURP, the depths of the coagulation zones with PKRP were significantly larger (225.09 ± 35.77 and 146.84 ± 18.91 µm, respectively, p< 0.01). Conclusions: PKRP ex vivo was associated with significantly better hemostasis than TURP.
Evaluation of Penile Rigidity with Color Doppler Flow Imaging in Chinese Patients with Erectile Dysfunction
Authors: Xuan Xujun , Wang Daohu , Sun Peng , Mei Hua
Published: May 2008

Objectives: To assess the role of color Doppler flow imaging (CDFI) in the evaluation of Chinese patients with erectile dysfunction (ED) and to explore the association between penile rigidity and hemodynamic parameters of CDFI. Methods: Totally 74 ED patients with an age range of 22–69 (median age 47) were included in our study, hemodynamic parameters including the peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) of the penile cavernous artery were measured by CDFI before and after intracavernous pharmacological testing. The degree of penile rigidity was classified according to Schramek grading system. The correlation between the penile rigidity state and its hemodynamic parameters was analyzed. Results: In ED patients, the abnormalities of cavernous artery and dorsal vein could be evaluated by the value of PSV and EDV with combination of penile rigidity. Among different penile rigidity status, the PSV, EDV and RI of the cavernous artery were significantly different (p < 0.05). The RI correlated significantly with the penile rigidity (r2 = 0.7948). Conclusion: The CDFI hemodynamics of the penile cavernous artery are helpful in the etiological diagnosis of Chinese ED patients and can be used as one of the quantitative indexes for penile rigidity, which is consistent with western guidelines.
Infected Retroperitoneal Cystic Lymphangioma Masquerading as Psoas Abscess
Authors: Pratap Akshay , Tiwari Awadhesh , Sah Birendra Prasad , Sinha Arvind Kumar , Shakya Vikal Chandra , Niels Koopmans G.
Published: May 2008

A 2-year-old male is described who presented with fever, fixed flexion deformity of the right hip and a tender mass in the right iliac fossa. A clinical diagnosis of psoas abscess was made. Abdominal ultrasound was suggestive of an echogenic retroperitoneal cyst but could not accurately determine the nature of the cyst. A contrast CT scan showed a retroperitoneal cyst. At laparotomy, a large retroperitoneal cyst containing turbid fluid was found and was excised completely. Histopathological examination was suggestive of cystic lymphangioma. Clinical presentation of retroperitoneal lymphangioma may be variable and misleading, therefore complex imaging studies are necessary in the evaluation of this condition.
Cancer in Kidney Transplantation
Authors: Zani D. , Simeone C. , Antonelli A. , Bettini E. , Moroni A. , Cosciani Cunico S.
Published: May 2008

Cancer in the transplanted kidney is rare, and its clinical and surgical management can be controversial. We report 3 cases of cancer in renal transplantation (1 case of renal cell carcinoma and 2 cases of transitional cell carcinoma) and their treatment. Our data and those reported in the literature suggest that these cancers can be treated like a neoplasm in the general population. However, a higher number of cases and longer follow-up periods are necessary to confirm our findings.
Renal Artery Pseudoaneurysm Occurring after Laparoscopic Partial Nephrectomy
Authors: Shigeta M. , Mita K. , Shoji K. , Marukawa K. , Toyota N. , Usui T.
Published: May 2008

Renal artery pseudoaneurysm (RAP) is rare, and has been reported after renal biopsy and percutaneous renal surgery. We report a case of RAP after laparoscopic partial nephrectomy for renal cell carcinoma.
Probability of Ten-Year Survival in Metastatic Renal Cell Carcinoma
Authors: Salagierski Maciej , Salagierski Marek , Salagierska-Barwińska Anna , Sosnowski Marek
Published: May 2008

Metastatic renal cancer has a very poor prognosis and constitutes a challenge to uro-oncologists. We present a patient who in the 10 years following the diagnosis of renal cell carcinoma developed nine consecutive metastases in as many sites. He was operated on eleven times in different departments and received systemic therapy. We performed two percutaneous radiofrequency ablations of the cancer mass in the remaining kidney, which gave him the possibility of preserving renal function and we used the ablation technique to coagulate the metastatic mass in the psoas muscle. Furthermore, we executed an adrenalectomy and removed the ablated kidney tumor. The patient’s long-term survival, as well as the various applications of radiofrequency ablation, would seem to be worth reporting.
Centric-fusion translocation and whole-arm heterochromatin in the karyotype of the blue fox (Alopex lagopus L.): synaptonemal complex analysis
Authors: Świtoński M. , Gustavsson I.
Published: May 2008

Conventional observations of mitotic chromosomes from two male blue foxes, revealing a centric-fusion translocation and whole-arm heterochromatin, were verified by synaptonemal complex analysis. This analysis revealed that the centric fusion had been preceded by a conspicuous loss of chromosome material in the two one-armed chromosomes involved, but the chromosomal origin of the centric-fusion kinetochore could not be established. The nontranslocated chromosomes of the trivalent, which in all cells but one were in cis configuration, had reached by early pachytene a stage in which almost complete homologous pairing and nonhomologous association or pairing of the free ends of the chromosomes could be observed. In later stages, complete pairing of the nontranslocated chromosomes with the corresponding arms of the centric-fusion translocation was seen occasionally. One to six autosomal bivalents demonstrated unpaired heterochromatic arms in early pachytene, and the heterochromatic chromosome arms were sometimes unpaired even in late pachytene. Some of them showed a distinct size heteromorphism in late zygotene and early pachytene. In most late-pachytene cells, however, the heteromorphic chromosomes were completely length-adjusted. Only a small fraction of the cells showed pairing interference between nonhomologous chromosomes.
Lack of association between prostate-specific acid phosphatase RFLP genotypes and prostatic cancer or benign prostatic hyperplasia
Authors: Leskelä S. , Virkkunen P. , Lukkarinen O. , Winqvist R. , Vihko P.
Published: May 2008

We have previously reported the identification and basic characterization of two biallelic TaqI RFLPs, A and B, of the 3’ end of the human ACPP locus in an unselected Finnish population (Winqvist et al., 1989). In the present investigation, a similar allelic distribution was observed in patients with prostatic cancer or benign hyperplasia. In addition, it was found that the DNA sequences generating RFLP-B are located further downstream from the RFLP-A sequences.
A fluorescence in situ hybridization technique for retrospective cytogenetic analysis
Authors: Babu V.R. , Wiktor A.
Published: May 2008

Fluorescence in situ hybridization (FISH) is being used increasingly in clinical practice; however, current FISH techniques require fresh material, and there is considerable variation in hybridization efficiency between laboratories. We have modified a FISH technique described by Pinkel et al. (1986) that works not only on freshly G-banded material but also on cytogenetic preparations ranging in age from 2 wk to 12yr. We have tested this technique on several centromeric alphoid satellite probes (D1Z5, D7Z1, D17Z1, DXZ1, and DYZ3) and one noncentromeric minisatellite probe (D1Z2). Our average hybridization efficiency on freshly banded preparations for these probes is consistently greater than 90 %. The combination of higher efficiency and the ability to perform hybridization on previously G-banded material makes this a valuable technique for retrospective analyses.
Fine mapping of human 5S rRNA genes to chromosome 1q42.11→q42.13
Authors: Sørensen P.D. , Lomholt B. , Frederiksen S. , Tommerup N.
Published: May 2008

The human 5S rRNA genes have been localized by in situ hybridization to metaphase chromosomes. Tritiated RNA probes were made by transcription from 2,300-bp and 638-bp DNA fragments containing an isolated human 5S rRNA gene. Hybridization to metaphase spreads from a balanced reciprocal translocation carrier, 46, XX, t(1;7)(q42.13;p11.1), showed that the 5S rRNA genes were entirely localized on the normal and the derivative chromosome 1. This narrows the chromosome position of the major fraction of 5S rRNA genes and pseudogenes to the region 1q42.11→q42.13.
Chromosomal assignment of four rat genes coding for the spermatid-specific proteins proacrosin (ACR), transition proteins 1 (TNP1) and 2 (TNP2), and protamine 1 (PRM1)
Authors: Adham I.M. , Szpirer C. , Kremling H. , Keime S. , Szpirer J. , Levan G. , Engel W.
Published: May 2008

The genes for proacrosin, protamines, and transition proteins are exclusively expressed in haploid spermatogenic cells. From the analysis of mouse × rat cell hybrids which segregate rat chromosomes, the rat gene for proacrosin (ACR) was assigned to chromosome 7, that for transition protein 1 (TNP1) to chromosome 9, and the genes for transition protein 2 (TNP2) and protamine 1 (PRM1) to chromosome 10.
Confirmation, via in situ hybridization, of the occurrence of Robertsonian translocations during lemur evolution by localization of GLUDP1 DNA sequences on lemur chromosomes
Authors: Jung K.Y. , Warter S. , Rumpler Y.
Published: May 2008

A human genomic DNA sequence derived from glutamate dehydrogenase pseudogene 1 was used as a probe for in situ hybridization to the chromosomes of three lemur species, Eulemur fulvus mayottensis (EFU), E. macaco macaco (EMA), and E. coronatus (ECO). This sequence, which is 98 % homologous to the nucleotide sequence of the gene for human glutamate dehydrogenase (GLUD), was found on homologous bands of three morphologically similar chromosome segments, EFU14, EMA5p, and EC08q, confirming that different Robertsonian translocations occurred during the evolution of these three species. These loci on the lemur chromosomes probably correspond to the human GLUD locus.
Chromosome condensation from prophase to late metaphase: relationship to chromosome bands and their replication time
Authors: Drouin R. , Lemieux N. , Richer C.-L.
Published: May 2008

As chromosomes condense during early mitosis, their subbands fuse in a highly coordinated fashion. Subband fusion occurs when two large subbands flanking one minor subband come together to form one band, which takes on the cytological characteristics of the original flanking subbands. Using four different banding techniques—GTG (G-bands obtained with trypsin and Giemsa), GBG (G-bands obtained with BrdU and Giemsa), RHG (R-bands obtained by heating and Giemsa), and RBG (R-bands obtained with BrdU and Giemsa)—we studied subband fusion from prophase (1,250 bands per haploid set) to late metaphase (300 bands). To quantify the condensation process, a fusion index was established. We found that chromosomes contain preferential zones of condensation. From prophase to late metaphase, the early replicating subbands (R-subbands) fuse more readily with each other than do the late-replicating subbands (G-subbands). R-bands usually replicate early and condense late independently of the adjacent G-bands, which replicate late but condense early. Therefore, chromosome bands can undergo DNA replication and chromatin condensation relatively autonomously. Our data suggest that (1) chromosome replication and condensation are closely connected in time, (2) the metaphase bands represent independent units of chromatin condensation, and (3) the condensation process is an important feature of chromosome organization.
Mapping of the MYC gene to band 8q24.12→q24.13 by R-banding and distal to fra(8)(q24.11), FRA8E, by fluorescence in situ hybridization
Authors: Takahashi E. , Hori T. , O’Connell P. , Leppert M. , White R.
Published: May 2008

The MYC gene was mapped to R-banded human prometaphase chromosomes and to chromosomes expressing fra(8)(q24.11) by fluorescence in situ hybridization. By high-resolution banding analysis, the fluorescent signals were localized to R-positive band q24.12→q24.13 of the long arm of chromosome 8. Furthermore, the signals were localized near the middle part, q24.12→q24.13, of the distal portion of fra(8)(q24.11) expression. Thus, the precise localization of MYC was to the subband 8q24.12→q24.13.
In situ hybridization of two markers closely flanking the spinal muscular atrophy gene to 5q12→q13.3
Authors: Mattei M.-G. , Melki J. , Bachelot M.-F. , Abdelhak S. , Burlet P. , Frézal J. , Munnich A.
Published: May 2008

In order to refine the physical location of the p105-153Ra and M4 probes which closely flank the spinal muscular atrophy gene (SMA) on human chromosome 5q, in situ hybridization has been carried out on prometaphase chromosomes. Our results demonstrate that the disease gene is located between the 5q12→q13.1 and 5q13.3 bands. The present study will hopefully contribute to microdissection of the chromosomal region of the SMA gene.
Regional localization of the human glutaminase (GLS) and interleukin-9 (IL9) genes by in situ hybridization
Authors: Modi W.S. , Pollock D.D. , Mock B.A. , Banner C. , Renauld J.-C. , Van Snick J.
Published: May 2008

Phosphate-activated glutaminase is found in mammalian small intestine, brain, and kidney, but not in liver. The enzyme initiates the catabolism of glutamine as the principal respiratory fuel in the small intestine, may synthesize the neuro-transmitter glutamate in the brain, and functions in the kidney to help maintain systemic pH homeostasis. Interleukin-9 (IL9) is a relatively new cytokine that supports the growth of helper T-cell clones, mast cells, and megakaryoblastic leukemia cells. cDNA clones have recently been obtained for each of these genes. The human loci for phosphate-activated glutaminase (GLS) and IL9 have previously been mapped to chromosomes 2 and 5, respectively, by analysis of somatic cell hybrid DNAs. By using chromosomal in situ hybridization, we have regionally mapped GLS to 2q32→q34 and IL9 to 5q31→q35.
Chromosomal location of the human tumor necrosis factor receptor genes
Authors: Baker E. , Chen L.Z. , Smith C.A. , Callen D.F. , Goodwin R. , Sutherland G.R.
Published: May 2008

TNFR1 and TNFR2, the genes encoding the two forms of the human tumor necrosis factor receptor, were localized to normal human chromosomes by in situ hybridization and Southern blot analysis of a series of human × mouse hybrid cell lines. TNFR1 maps to 12p13 and TNFR2 maps to 1p36.
Assignment of the fucosidase pseudogene FUCA1P to chromosome region 2q31→q32
Authors: Coucke P. , Mangelschots K. , Speleman F. , Bossuyt P. , Van Oostveldt P. , Van der Auwera B. , Carritt B. , Willems P.J.
Published: May 2008

FUCAIP is a pseudogene of the structural fucosidase gene FUCA1. The former has been mapped to human chromosome 2, whereas the latter has been localized to chromosome 1p34→p36. We have further localized FUCAIP to chromosomal band 2q31→q32 by fluorescent in situ hybridization and digital imaging microscopy. This localization was confirmed by linkage analysis between FUCAIP and the COL3A1 gene in 2q24→q32 which gave maximal lod scores of 4.03 at 3 % recombination.
Mapping HSA10 homologous loci in cattle
Authors: Threadgill D.S. , Womack J.E.
Published: May 2008

Loci homologous to those on human chromosome 10 (HSA10) map to five mouse chromosomes, MMU2, MMU7, MMU10, MMU14, and MMU19. In cattle, one unassigned syntenic group (U26) was previously defined by the HS A10/MMU19 isoenzyme marker glutamic-oxaloacetic transaminase 1 (GOT1). To evaluate the syntenic arrangement of other HSA10 loci in cattle, seven genes were physically mapped by segregation analysis in a bovine × hamster hybrid somatic cell panel. The genes mapped include: vimentin (VIM) on HSA10 and MMU2; interleukin 2 receptor (IL2R) on HSA10 and MMU?; ornithine aminotransferase (OAT) on HSA10 and MMU7; hexokinase 1 (HKl) on HSA10 and MMU 10; retinol-binding protein 3 (RBP3) on HSA10 and MMU 14; plasminogen activator, urokinase type (PLAU) on HSA10 and MMU 14; and α-2-adrenergic receptor (ADRA2) on HSA10 and MMU 19. VIM and IL2R mapped to Ul 1; ADRA2 and OAT mapped to U26; and RBP3, PLAU, and HKl mapped to U28.