bluuebunny/crossref_metadata_2025 huggingface dataset:
Reference radiochromic film dosimetry in kilovoltage photon beams during CBCT image acquisition
Authors: Tomic Nada , Devic Slobodan , DeBlois François , Seuntjens Jan
Published: March 2010

Purpose:

A common approach for dose assessment during cone beam computed tomography (CBCT) acquisition is to use thermoluminescent detectors for skin dose measurements (on patients or phantoms) or ionization chamber (in phantoms) for body dose measurements. However, the benefits of a daily CBCT image acquisition such as margin reduction in planning target volume and the image quality must be weighted against the extra dose received during CBCT acquisitions.

Methods:

The authors describe a two‐dimensional reference dosimetry technique for measuring dose from CBCT scans using the on‐board imaging system on a Varian Clinac‐iX linear accelerator that employs the XR‐QA radiochromic film model, specifically designed for dose measurements at low energy photons. The CBCT dose measurements were performed for three different body regions (head and neck, pelvis, and thorax) using humanoid Rando phantom.

Results:

The authors report on both surface dose and dose profiles measurements during clinical CBCT procedures carried out on a humanoid Rando phantom. Our measurements show that the surface doses per CBCT scan can range anywhere between 0.1 and 4.7 cGy, with the lowest surface dose observed in the head and neck region, while the highest surface dose was observed for the Pelvis spot light CBCT protocol in the pelvic region, on the posterior side of the Rando phantom. The authors also present results of the uncertainty analysis of our XR‐QA radiochromic film dosimetry system.

Conclusions:

Radiochromic film dosimetry protocol described in this work was used to perform dose measurements during CBCT acquisitions with the one‐sigma dose measurement uncertainty of up to 3% for doses above 1 cGy. Our protocol is based on film exposure calibration in terms of “air kerma in air,” which simplifies both the calibration procedure and reference dosimetry measurements. The results from a full Monte Carlo investigation of the dose conversion of measured XR‐QA film dose at the surface into dose to water (or water kerma) at the surface of the phantom indicate that, for typical beam qualities used in CBCT, this conversion can be approximated by simple mass‐energy absorption coefficient ratios water‐to‐air.
Effective learning strategies for real‐time image‐guided adaptive control of multiple‐source hyperthermia applicators
Authors: Cheng Kung‐Shan , Dewhirst Mark W. , Stauffer Paul R. , Das Shiva
Published: March 2010

Purpose:

This paper investigates overall theoretical requirements for reducing the times required for the iterative learning of a real‐time image‐guided adaptive control routine for multiple‐source heat applicators, as used in hyperthermia and thermal ablative therapy for cancer.

Methods:

Methods for partial reconstruction of the physical system with and without model reduction to find solutions within a clinically practical timeframe were analyzed. A mathematical analysis based on the Fredholm alternative theorem (FAT) was used to compactly analyze the existence and uniqueness of the optimal heating vector under two fundamental situations: (1) noiseless partial reconstruction and (2) noisy partial reconstruction. These results were coupled with a method for further acceleration of the solution using virtual source (VS) model reduction. The matrix approximation theorem (MAT) was used to choose the optimal vectors spanning the reduced‐order subspace to reduce the time for system reconstruction and to determine the associated approximation error. Numerical simulations of the adaptive control of hyperthermia using VS were also performed to test the predictions derived from the theoretical analysis. A thigh sarcoma patient model surrounded by a ten‐antenna phased‐array applicator was retained for this purpose. The impacts of the convective cooling from blood flow and the presence of sudden increase of perfusion in muscle and tumor were also simulated.

Results:

By FAT, partial system reconstruction directly conducted in the full space of the physical variables such as phases and magnitudes of the heat sources cannot guarantee reconstructing the optimal system to determine the global optimal setting of the heat sources. A remedy for this limitation is to conduct the partial reconstruction within a reduced‐order subspace spanned by the first few maximum eigenvectors of the true system matrix. By MAT, this VS subspace is the optimal one when the goal is to maximize the average tumor temperature. When more than 6 sources present, the steps required for a nonlinear learning scheme is theoretically fewer than that of a linear one, however, finite number of iterative corrections is necessary for a single learning step of a nonlinear algorithm. Thus, the actual computational workload for a nonlinear algorithm is not necessarily less than that required by a linear algorithm.

Conclusions:

Based on the analysis presented herein, obtaining a unique global optimal heating vector for a multiple‐source applicator within the constraints of real‐time clinical hyperthermia treatments and thermal ablative therapies appears attainable using partial reconstruction with minimum norm least‐squares method with supplemental equations. One way to supplement equations is the inclusion of a method of model reduction.
Three‐dimensional quantitative evaluation method of nonrigid registration algorithms for adaptive radiotherapy
Authors: Rodriguez‐Vila B. , Gaya F. , Garcia‐Vicente F. , Gomez E. J.
Published: March 2010

Purpose:

Current radiotherapy is progressing to the concept of adaptive radiotherapy, which implies the adaptation of planning along the treatment course. Nonrigid registration is an essential image processing tool for adaptive radiotherapy and image guided radiotherapy, and the three‐dimensional (3D) nature of the current radiotherapy techniques requires a 3D quantification of the registration error that existing evaluation methods do not cover appropriately. The authors present a method for 3D evaluation of nonrigid registration algorithms’ performance, based on organ delineations, capable of working with near‐spherical volumes even in the presence of concavities.

Methods:

The evaluation method is composed by a volume shape description stage, developed using a newad hoc volume reconstruction algorithm proposed by the authors, and an error quantification stage. The evaluation method is applied to the organ delineations of prostate and seminal vesicles, obtained by an automatic segmentation method over images of prostate cancer patients treated with intensity modulated radiation therapy.

Results:

The volume reconstruction algorithm proposed has been shown to accurately model complex 3D surfaces by the definition of clusters of control points. The quantification method, inspired by the Haussdorf–Chebysev distance, provides a measure of the largest registration error per control direction, defining a valid metric for concave‐convex volumes. Summarizing, the proposed evaluation methodology presents accurate results with a high spatial resolution in a negligible computation time in comparison with the nonrigid registration time.

Conclusions:

Experimental results show that the metric selected for quantifying the registration error is of utmost importance in a quantitative evaluation based on measuring distances between volumes. The accuracy of the volume reconstruction algorithm is not so relevant as long as the reconstruction is tight enough on the actual volume of the organ. The new evaluation method provides a smooth and accurate volume reconstruction for both the reference and the registered organ, and a complete 3D description of nonrigid registration algorithms’ performance, resulting in a useful tool for study and comparison of registration algorithms for adaptive radiotherapy.
Evaluation of the spatial dependence of the point spread function in 2D PET image reconstruction using LOR‐OSEM
Authors: Wiant D. , Gersh J. A. , Bennett M. , Bourland J. D.
Published: March 2010

Purpose:

The use of positron emission tomography (PET) imaging has proved beneficial in the staging and diagnosis of several cancer disease sites. Additional applications of PET imaging in treatment planning and the evaluation of treatment response are limited by the relatively low spatial resolution of PET images. Including point spread function (PSF) information in the system matrix (SM) of iterative reconstruction techniques has been shown to produce improved spatial resolution in PET images.

Methods:

In this study, the authors sampled the spatially variant PSF at over 6000 locations in the field of view for a General Electric Discovery ST PET/CT (General Electric Healthcare, Waukesha, WI) scanner in 2D acquisition mode. The authors developed PSF blurred SMs based on different combinations of the radial, depth, and azimuthal spatial dependencies to test the overall spatial dependence of the PSF on image quality. The PSF blurred SMs were included in a LOR‐OSEM reconstruction algorithm and used for image reconstruction of geometric phantoms. The authors also examined the effect of sampling density on PSF characterization to design a more efficient sampling scheme.

Results:

The authors found that depth dependent change in the amplitude of the detector response was the most important factor affecting image quality. A SM created from a PSF that introduced (perpendicular to the LOR), (parallel to the LOR), or and dependent blurring across the radial lines of response led to visually identifiable improvements in spatial resolution and contrast in reconstructed images compared to images reconstructed with a purely geometric SM with no PSF blurring. Images reconstructed using a SM with and dependent blurring across the radial lines of response showed improved spatial resolution and contrast‐noise ratios compared to images reconstructed with a SM that had only dependent blurring. Additionally, the authors determined that the PSF could be adequately characterized with roughly 85% fewer samples through the use of a better optimized sampling scheme.

Conclusions:

PET image reconstruction using a SM made from an accurately characterized PSF that accounts for and dependencies results in improved spatial resolution and contrast‐noise relations, which may aid in lesion boundary detection for treatment planning or quantitative assessment of treatment response.
Intensity modulated proton therapy treatment planning using single‐field optimization: The impact of monitor unit constraints on plan quality
Authors: Zhu X. R. , Sahoo N. , Zhang X. , Robertson D. , Li H. , Choi S. , Lee A. K. , Gillin M. T.
Published: March 2010

Purpose:

To investigate the effect of monitor unit (MU) constraints on the dose distribution created by intensity modulated proton therapy (IMPT) treatment planning using single‐field optimization (SFO).

Methods:

Ninety‐four energies between 72.5 and 221.8 MeV are available for scanning beam IMPT delivery at our institution. The minimum and maximum MUs for delivering each pencil beam (spot) are 0.005 and 0.04, respectively. These MU constraints are not considered during optimization by the treatment planning system; spots are converted to deliverable MUs during postprocessing. Treatment plans for delivering uniform doses to rectangular volumes with and without MU constraints were generated for different target doses, spot spacings, spread‐out Bragg peak (SOBP) widths, and ranges in a homogeneous phantom. Four prostate cancer patients were planned with and without MU constraints using different spot spacings. Rounding errors were analyzed using an in‐house software tool.

Results:

From the phantom study, the authors have found that both the number of spots that have rounding errors and the magnitude of the distortion of the dose distribution from the ideally optimized distribution increases as the field dose, spot spacing, and range decrease and as the SOBP width increases. From our study of patient plans, it is clear that as the spot spacing decreases the rounding error increases, and the dose coverage of the target volume becomes unacceptable for very small spot spacings.

Conclusions:

Constraints on deliverable MU for each spot could create a significant distortion from the ideally optimized dose distributions for IMPT fields using SFO. To eliminate this problem, the treatment planning system should incorporate the MU constraints in the optimization process and the delivery system should reliably delivery smaller minimum MUs.
Prediction of stopping‐power ratios in flattening‐filter free beams
Authors: Ceberg Crister , Johnsson Stefan , Lind Mårten , Knöös Tommy
Published: March 2010

Purpose:

In recent years, there has been an increasing interest in flattening‐filter free (FFF) beams. However, since the removal of the flattening filter will affect both the mean and the variance of the energy spectrum, current beam‐quality specifiers may not be adequate for reference dosimetry in such beams. The purpose of this work was to investigate an alternative, more general beam‐quality specifier.

Methods:

The beam‐quality specifier used in this work was a combination of the kerma‐weighted mean and the coefficient of variation of the linear attenuation coefficient in water. These parameters can in theory be determined from narrow‐beam transmission measurements using a miniphantom “in‐air,” which is a measurement condition well suited also to small and nonstandard fields. The relation between the Spencer‐Attix stopping‐power ratios and this novel beam‐quality specifier was described by a simple polynomial. For reference, the authors used Monte Carlo calculated spectra and stopping‐power data for nine different beams, with and without flattening filter.

Results:

The polynomial coefficients were obtained by least‐squares optimization. For all beams included in this investigation, the average of the differences between the predicted and the Monte Carlo calculated stopping‐power ratios was (1 SD) (including TomoTherapy and CyberKnife example beams).

Conclusions:

An alternative dual‐parameter beam‐quality specifier was investigated. The evaluation suggests that it can be used successfully to predict stopping‐power ratios in FFF as well as conventional beams, regardless of filtration.
Attenuation‐emission alignment in cardiac PET/CT based on consistency conditions
Authors: Alessio Adam M. , Kinahan Paul E. , Champley Kyle M. , Caldwell James H.
Published: March 2010

Purpose:

In cardiac PET and PET/CT imaging, misaligned transmission and emission images are a common problem due to respiratory and cardiac motion. This misalignment leads to erroneous attenuation correction and can cause errors in perfusion mapping and quantification. This study develops and tests a method for automated alignment of attenuation and emission data.

Methods:

The CT‐based attenuation map is iteratively transformed until the attenuation corrected emission data minimize an objective function based on the Radon consistency conditions. The alignment process is derived from previous work by Welch et al. [“Attenuation correction in PET using consistency information,” IEEE Trans. Nucl. Sci. 45, 3134–3141 (1998)] for stand‐alone PET imaging. The process was evaluated with the simulated data and measured patient data from multiple cardiac ammonia PET/CT exams. The alignment procedure was applied to simulations of five different noise levels with three different initial attenuation maps. For the measured patient data, the alignment procedure was applied to eight attenuation‐emission combinations with initially acceptable alignment and eight combinations with unacceptable alignment. The initially acceptable alignment studies were forced out of alignment a known amount and quantitatively evaluated for alignment and perfusion accuracy. The initially unacceptable studies were compared to the proposed aligned images in a blinded side‐by‐side review.

Results:

The proposed automatic alignment procedure reduced errors in the simulated data and iteratively approaches global minimum solutions with the patient data. In simulations, the alignment procedure reduced the root mean square error to less than 5 mm and reduces the axial translation error to less than 1 mm. In patient studies, the procedure reduced the translation error by and resolved perfusion artifacts after a known misalignment for the eight initially acceptable patient combinations. The side‐by‐side review of the proposed aligned attenuation‐emission maps and initially misaligned attenuation‐emission maps revealed that reviewers preferred the proposed aligned maps in all cases, except one inconclusive case.

Conclusions:

The proposed alignment procedure offers an automatic method to reduce attenuation correction artifacts in cardiac PET/CT and provides a viable supplement to subjective manual realignment tools.
Technical Note: EGSnrc‐based dosimetric study of the BEBIG HDR brachytherapy sources
Authors: Selvam T. Palani , Bhola Subhalaxmi
Published: March 2010

Purpose:

The purpose of this work is to calculate two‐dimensional (2D) dose rate distributions around the BEBIG (Eckert & Ziegler, BEBIG GmbH, Germany) models GK60M21 (old) and Co0.A86 (new) high dose rate brachytherapy sources in an unbounded liquid water phantom. The study includes calculation of absorbed dose to water‐kerma ratio around the BEBIG sources and a point source in water. A comparison is made with previously published data.

Methods:

The EGSnrcMP Monte Carlo code system is used to calculate the absorbed dose and water‐kerma in water and air‐kerma strength in vacuum. EGSnrcMP‐based user codes such as EDKnrc, FLURZnrc, and DOSRZnrc are employed in the work.

Results:

The value of reaches a maximum of for the point source (constant between 3.6 and 4.5 mm from the source) and for the BEBIG sources (constant between 2.6 and 3.2 mm along the transverse axis of the sources). Dose rate data for the new and old sources are comparable to published data for radial distances . Differences up to 9% are observed at points close to the source . In addition for the new source, compared to previously published data, dose rate data are higher by 14% along the longitudinal axis where the source cable is connected. Dose rate differences on the longitudinal axis of this source are explained by varying the length of the simulated source cable.

Conclusions:

The 2D rectangular data set calculated in the present work could be considered for quality control on radiotherapy treatment planning systems.
Safety and Efficacy of Subretinal Readministration of a Viral Vector in Large Animals to Treat Congenital Blindness
Authors: Amado Defne , Mingozzi Federico , Hui Daniel , Bennicelli Jeannette L. , Wei Zhangyong , Chen Yifeng , Bote Erin , Grant Rebecca L. , Golden Jeffrey A. , Narfstrom Kristina , Syed Nasreen A. , Orlin Stephen E. , High Katherine A. , Maguire Albert M. , Bennett Jean
Published: March 2010

After successful gene therapy to correct retinal degeneration in one eye, treatment of the second eye is safe and effective—even when immunity to the vector is present—in nonhuman primates and dogs.
Emerging Targets
Authors: Ahmad Shama
Published: March 2010

Adenosine signaling and metabolism are altered in chronic airway diseases, suggesting targets for intervention.
Building Better Bones
Authors: Buettner Christoph
Published: March 2010

Inhibition of serotonin synthesis in the gut leads to an increase in bone mass and may represent an anabolic treatment for osteoporosis.
Nurturing the Impulse to Supersize
Authors: Minzenberg Michael J.
Published: March 2010

Consumption of high-fat food affects neurotrophic factors in the brain’s reward system, triggering consumption of more high-fat food.
The Double Life of RAF
Authors: Morozov Alexei
Published: March 2010

Drugs that inhibit RAF kinase in cancer cells show success in the clinic. But how exactly do they work?
Exposure to smoking in movies among British adolescents 2001–2006: Table 1
Authors: Anderson Stacey J , Millett Christopher , Polansky Jonathan R , Glantz Stanton A
Published: March 2010

Objective

To estimate youth exposure to smoking in movies in the UK and compare the likely effect with the USA.

Methods

We collected tobacco occurrences data for 572 top-grossing films in the UK screened from 2001 to 2006 and estimated the number of on-screen tobacco impressions delivered to British youths in this time period.

Results

91% of films in our sample that contained smoking were youth-rated films (British Board of Film Classification rating ‘15’ and lower), delivering at least 1.10 billion tobacco impressions to British youths during theatrical release. British youths were exposed to 28% more smoking impressions in UK youth-rated movies than American youth-rated movies, because 79% of movies rated for adults in the USA (‘R’) are classified as suitable for youths in the UK (‘15’ or ‘12A’).

Conclusion

Because there is a dose-response relation between the amount of on-screen exposure to smoking and the likelihood that adolescents will begin smoking, the fact that there is substantially higher exposure to smoking in youth-rated films in the UK than in the USA suggests that the fraction of all youth smoking because of films in the UK is probably larger than in the USA. Other countries with ratings systems that are less conservative (in terms of language and sexuality) than the USA will also be likely to deliver more on-screen tobacco impressions to youths. Assigning an ‘18’ classification to movies that contain smoking would substantially reduce youth exposure to on-screen smoking and, hence, smoking initiation among British youths.
IMPROVED LOW-POWER HIGH-SPEED BUFFER AMPLIFIER WITH SLEW-RATE ENHANCEMENT FOR LCD APPLICATIONS
Authors: MARANO DAVIDE , PALUMBO GAETANO , PENNISI SALVATORE
Published: March 2010

The present paper addresses an improved low-power high-speed buffer amplifier topology for large-size liquid crystal display applications. The proposed buffer achieves high-speed driving performance while drawing a low quiescent current during static operation. The circuit offers enhanced slewing capabilities with a limited power consumption by exploiting a slew detector which monitors the output voltage of the input differential amplifier and outputs an additional current signal providing slew-rate enhancement at the output stage. Post-layout simulations show that the proposed buffer can drive a 1 nF column line load with 8.5 V/μs slew-rate and 0.8 μs settling time, while drawing only 8 μA static current from a 3 V power supply.
TWO-PHASE SINUSOIDAL POWER-CLOCKED QUASI-ADIABATIC LOGIC CIRCUITS
Authors: KANCHANA BHAASKARAN V. S. , RAINA J. P.
Published: March 2010

This paper presents the design and performance analysis of the dual-rail encoded and sense-amplifier structured 2N–2P, 2N–2N2P, IPGL and PFAL quasi-adiabatic circuits operated by two-phase sinusoidal power-clock sources. The energetics of these families are studied for varying power-clock voltages. The drivability characteristics are evaluated using capacitive loads. The performance validation is made through 8-bit and 16-bit adder circuits using an integrated power-clock generator. Optimal adiabatic gain values are achieved for 2N–2N2P and IPGL circuits across a wide frequency range. Energy recovery comparison between the four-phase ramp and two-phase sine power-clocks is made. The results demonstrate the efficiency of sinusoidal power clock at both the high and the low frequency ranges of operation. The circuits were designed using 180 nm CMOS technology.
DESIGN AND SIMULATION OF MODULAR QUANTUM-DOT CELLULAR AUTOMATA MULTIPLEXERS FOR MEMORY ACCESSING
Authors: MARDIRIS VASILIOS A. , KARAFYLLIDIS IOANNIS G.
Published: March 2010

Multiplexers are extremely important parts of signal control systems. Some critical circuits of computing systems, like memories, use large multiplexers in order to present the value of a specific memory cell to their output. Several quantum-dot cellular automata (QCA) circuits have been designed and the need for a QCA memory access system becomes prominent. A modular 2n to 1 QCA multiplexer covering small area could reduce the size of such circuits and conclusively could increase circuit integration. In this paper we present a novel design of a small size, modular quantum-dot cellular automata (QCA) 2n to 1 multiplexer that can be used for memory addressing. The design objective is to develop a modular design methodology which can be used to implement 2n to 1 multiplexers using building blocks. For the QCA implementation a careful consideration is taken into account concerning the design in order to increase the circuit stability.
OPTIMUM BLOCK ADAPTIVE ICA FOR SEPARATION OF REAL AND COMPLEX SIGNALS WITH KNOWN SOURCE DISTRIBUTIONS IN DYNAMIC FLAT FADING ENVIRONMENTS
Authors: RANGANATHAN RAGHURAM , YANG THOMAS , MIKHAEL WASFY B.
Published: March 2010

Efficient co-channel and adjacent channel interference rejection is often one of the most demanding requirements for wireless receivers. Independent Component Analysis (ICA) has been previously applied to realize interference suppression. In particular, the fixed-point FastICA and complex FastICA algorithms can successfully perform blind signal extraction for real and complex valued communication signals in stationary or slow fading environments. Both algorithms exhibit fast convergence speed and impressive accuracy due to their Newton type fixed-point iteration. However, under dynamic channel conditions often encountered in practice, the fixed-point algorithms' performance is significantly degraded. In this contribution, a novel complex block adaptive ICA algorithm and its simplified real version is proposed, that overcome this limitation for the separation of complex valued and real signals with known source distributions. The new methods exploit prior information about the modulation scheme of the communication signals of interest, and achieve improved interference suppression performance in dynamic channel environments. The proposed complex ICA algorithm is called Complex Optimum Block Adaptive ICA (Complex OBA-ICA), and its abridged version for separating real signals is called General Optimum Block Adaptation ICA (GOBA-ICA). The proposed methods are applied to interference rejection in linearly and abruptly flat fading dynamic environments for diversity QPSK and BPSK wireless receivers. Simulation results show that the presented techniques demonstrate better convergence properties and accuracy as compared to the complex FastICA and FastICA algorithms.
HARDWARE IMPLEMENTATION AND VERIFICATION OF FIR FILTER UTILIZING M-BIT PDA
Authors: JENG SHIANN-SHIUN , LIN HSING-CHEN , CHEN CHUN-CHYUAN , CHANG SHU-MING
Published: March 2010

An efficient architecture for a FPGA symmetry FIR filter is proposed that employs the M-bit parallel-distributed arithmetic (M-bit PDA). The partial product is pre-calculated and saved into the distributed ROM to eliminate a large amount of multiplications. Altera Stratix II EP2S60 is used as a target device to implement the M-bit PDA. The hardware implementation requires 936 adaptive look-up tables (ALUTs), 888 registers, 1 PLL, 40960 memory bits for the FIR filter implementation with the M-bit PDA (in this case M = 2). Additionally, the maximum clock rate for this implementation can be achieved up to 155.36 MHz. In comparison with the parallel multiplier/adder cell (MAC) and serial distributed arithmetic (SDA), the proposed architecture consumes a smaller area and operates with a higher speed due to omitting the multipliers.
A GEOMETRIC SPANNER OF SEGMENTS
Authors: XU JINHUI , YANG YANG , ZHU YONGDING , KATOH NAOKI
Published: March 2010

Geometric spanner is a fundamental structure in computational geometry and plays an important role in many geometric networks design applications. In this paper, we consider a generalization of the classical geometric spanner problem (called segment spanner): Given a set S of n disjoint 2-D segments, find a spanning network GS with minimum size so that for any pair of points in S, there exists a path in GS with length no more than t times their Euclidean distance. Based on a number of interesting techniques (such as weakly dominating set, strongly dominating set, interval cover, and imaginary Steiner points), we present an efficient algorithm to construct the segment spanner. Our approach first identifies a set Q of Steiner points in S and then constructs a point spanner for the set of Steiner points. Our algorithm runs in O(|Q| + n2 log n) time and Q is a constant approximation (in terms of its size) of the optimal solution when S has a constant relative separation ratio. The approximation ratio depends on the stretch factor t and the relative separation ratio of S.
OPTIMAL TRIANGULATIONS OF POINTS AND SEGMENTS WITH STEINER POINTS
Authors: ARONOV BORIS , ASANO TETSUO , FUNKE STEFAN
Published: March 2010

Consider a set X of points in the plane and a set E of non-crossing segments with endpoints in X. One can efficiently compute the triangulation of the convex hull of the points, which uses X as the vertex set, respects E, and maximizes the minimum internal angle of a triangle.

In this paper we consider a natural extension of this problem: Given in addition a Steiner pointp, determine the optimal location of p and a triangulation of X ∪ {p} respecting E, which is best among all triangulations and placements of p in terms of maximizing the minimum internal angle of a triangle. We present a polynomial-time algorithm for this problem and then extend our solution to handle any constant number of Steiner points.
LOCAL SMOOTH SOLUTIONS OF A THIN SPRAY MODEL WITH COLLISIONS
Authors: MATHIAUD JULIEN
Published: March 2010

Sprays are complex flows made of liquid droplets surrounded by a gas. The aim of this paper is to study the local in time well-posedness of a collisional thin spray model, that is a coupling between Euler equations for a perfect gas and a Vlasov–Boltzmann equation for the droplets. We prove the existence and uniqueness of (local in time) solutions for this problem as soon as initial data are smooth enough.
On Hastings' Counterexamples to the Minimum Output Entropy Additivity Conjecture
Authors: Brandão Fernando G. S. L. , Horodecki Michał
Published: March 2010

Hastings recently reported a randomized construction of channels violating the minimum output entropy additivity conjecture. Here we revisit his argument, presenting a simplified proof. In particular, we do not resort to the exact probability distribution of the Schmidt coefficients of a random bipartite pure state, as in the original proof, but rather derive the necessary large deviation bounds by a concentration of measure argument. Furthermore, we prove non-additivity for the overwhelming majority of channels consisting of a Haar random isometry followed by partial trace over the environment, for an environment dimension much bigger than the output dimension. This makes Hastings' original reasoning clearer and extends the class of channels for which additivity can be shown to be violated.
Qubit Dynamics in a q-Deformed Oscillators Environment
Authors: L'Innocente Sonia , Lupo Cosmo , Mancini Stefano
Published: March 2010

We study the dynamics of one and two qubits plunged in a q-deformed oscillators environment. Specifically we evaluate the decay of quantum coherence and entanglement in time when passing from bosonic to fermionic environments. Slowing down of decoherence in the fermionic case is found. The effect manifests itself only at finite temperature.
Arithmetic of Partial Fibres in Relative Position Space of Bethe Ansatz
Authors: Milewski Jan , Banaszak Grzegorz , Lulek Tadeusz
Published: March 2010

We consider fibration of the relative position space for the system of r Bethe pseudoparticles on a ring of N nodes. We define primary and secondary configurations in the relative position space. We study cardinalities of the set of primary configurations and of the partial fibres of the fibration.
Adiponectin diminishes platelet aggregation and sCD40L release. Potential role in the metabolic syndrome
Authors: Restituto P. , Colina I. , Varo J. J. , Varo N.
Published: March 2010

The proinflammatory and proatherogenic mediator, soluble CD40 ligand (CD40L), is increased in the metabolic syndrome (MS) and released from platelets. We hypothesized that adiponectin modulates platelet function, and we sought to evaluate the association of adiponectin and sCD40L levels with platelet aggregation in MS and the effects of adiponectin on platelet aggregation and activation. Platelet aggregation and circulating adiponectin, sCD40L and P-selectin were determined in 30 controls and 30 patients with MS. Also, in vitro studies were performed in platelet-rich plasma from nine healthy volunteers. Adiponectin receptors were demonstrated by Western blotting and flow cytometry. ADP and epinephrine platelet aggregation was measured after preincubation with adiponectin. sCD40L and P-selectin secretion was measured in the supernatants by ELISA. Patients with MS had higher sCD40L and P-selectin than controls (5.96 ± 0.50 vs. 4.28 ± 0.41 ng/ml, P < 0.05, and 151 ± 8 vs. 122 ± 9 ng/ml, P < 0.05). By contrast, adiponectin was lower in patients with MS than in controls (5.25 ± 0.30 vs. 7.35 ± 0.34 μg/ml, P < 0.001). Higher platelet aggregation was found in MS. Adiponectin inversely correlated with P-selectin ( R = −0.35, P = 0.009), sCD40L ( r = −0.24, P = 0.05) and epinephrine and collagen induced aggregation ( r = −0.80, P = 0.005; r = −0.70, P = 0.011). Platelets express the receptors for adiponectin. Platelet aggregatory response to epinephrine and ADP significantly decreased following preincubation with adiponectin (96 ± 4 vs. 23 ± 3%, P < 0.001, and 102 ± 9 vs. 85 ± 9%, P = 0.004). Adiponectin prevented platelet sCD40L release (1.63 ± 0.15 vs. 2.04 ± 0.20 ng/ml, P < 0.001). Enhanced platelet aggregation and activation markers are found in MS associated with low adiponectin concentrations. Novel evidence is provided demonstrating that adiponectin has antithrombotic properties, since it inhibits platelet aggregation and platelet activation.
Renal capsule as a stem cell niche
Authors: Park Hyeong-Cheon , Yasuda Kaoru , Kuo Mei-Chuan , Ni Jie , Ratliff Brian , Chander Praveen , Goligorsky Michael S.
Published: March 2010

Renal resident stem cells were previously reported within the renal tubules and papillary area. The aim of the present study was to determine whether renal capsules harbor stem cells and whether this pool can be recruited to the renal parenchyma after ischemic injury. We demonstrated the presence of label-retaining cells throughout the renal capsule, at a density of ∼10 cells/mm2, and their close apposition to the blood vessels. By flow cytometry, in vitro cultured cells derived from the renal capsule were positive for mesenchymal stem cell (MSC) markers (CD29+, vimentin+, Sca-1+, nestin+) but did not express hematopoietic and endothelial stem cell markers. Moreover, renal capsule-derived cells also exhibited self-renewal, clonogenicity, and multipotency in differentiation conditions, all favoring stem cell characteristics and identifying them with MSC. In situ labeling of renal capsules with CM-DiI CellTracker demonstrated in vivo a directed migration of CM-DiI-labeled cells to the ischemic renal parenchyma, with the rate of migration averaging 30 μm/h. Decapsulation of the kidneys during ischemia resulted in a modest, but statistically significant, deceleration of recovery of plasma creatinine compared with ischemic kidneys with intact renal capsule. Comparison of these conditions allows the conclusion that renal capsular cells may contribute ∼25–30% of the recovery from ischemia. In conclusion, the data suggest that the renal capsule may function as a novel stem cell niche harboring MSC capable of participating in the repair of renal injury.
Direct fibrogenic effects of aldosterone on normotensive kidney: an effect modified by 11β-HSD activity
Authors: Brem Andrew S. , Morris David J. , Ge Yan , Dworkin Lance , Tolbert Evelyn , Gong Rujun
Published: March 2010

Aldosterone (Aldo) can be a profibrotic factor in cardiovascular and renal tissues. This study tests the hypothesis that prolonged Aldo exposure is able to directly induce fibrotic changes in the kidney of a normal nonhypertensive animal. Immortalized rat proximal tubule cells (IRPTC) containing 11β-hydroxysteroid dehydrogenase (11β-HSD1) but no mineralocorticoid receptors (MR) and mouse inner medullary collecting duct cells (IMCD) containing 11β-HSD2 and MR were examined. IRPTC exposed to Aldo or corticosterone (10 nM) for 48 h demonstrated no change in collagen production as assessed by Sirius red staining. In contrast, IMCD treated with Aldo exhibited a marked increase in the expression of collagen, fibronectin, and connective tissue growth factor (CTGF), whereas corticosterone alone had no effect. The Aldo-induced overexperession of collagen, fibronectin, and CTGF was substantially attenuated by the MR antagonist RU-318 and by the 11β-HSD end product 11-dehydrocorticosterone, but not by the glucocorticoid receptor antagonist RU-486. In vivo, early fibrotic changes with elevated collagen, fibronectin, and CTGF expression were observed in kidneys isolated from normotensive adrenalectomized mice receiving a continuous infusion of Aldo (8 μg·kg−1·day−1) for 1 wk. These changes were not present in corticosterone-treated mice. Aldo-induced changes were attenuated in adrenally intact mice and in mice treated with RU-318 or 11-dehydrocorticosterone. Thus, extended Aldo exposure produces fibrotic changes in cells containing MR and in normal kidneys. MR antagonists and the end products of 11β-HSD attenuate these fibrogenic effects.
Suppression subtractive hybridization analysis of low-protein diet- and vitamin D-induced gene expression from rat kidney inner medullary base
Authors: Chen Guangping , Yang Yuan , Fröhlich Otto , Klein Janet D. , Sands Jeff M.
Published: March 2010

Protein restriction and hypercalcemia result in a urinary concentrating defect in rats and humans. Previous tubular perfusion studies show that there is an increased active urea transport activity in the initial inner medullary (IM) collecting duct in low-protein diet (LPD) and vitamin D (Vit D) animal models. To investigate the possible mechanisms that cause the urinary concentrating defect and to clone the new active urea transporter, we employed a modified two-tester suppression subtractive hybridization (ttSSH) approach and examined gene expression induced by LPD and Vit D in kidney IM base. Approximately 600 clones from the subtracted library were randomly selected; 150 clones were further confirmed to be the true positive genes by slot blot hybridization with subtracted probes from LPD and Vit D and sent for DNA sequencing. We identified 10 channel/transporter genes that were upregulated in IM base in LPD and Vit D animal models; 8 were confirmed by real-time PCR. These genes include aquaporin 2 (AQP2), two-pore calcium channel protein 2, brain-specific organic cation transporter, Na+- and H+-coupled glutamine transporter, and solute carrier family 25. Nine genes are totally new, and twelve are uncharacterized hypothetical proteins. Among them, four genes were shown to be new transmembrane proteins as judged by Kyte-Doolittle hydrophobic plot analysis. ttSSH provides a useful method to identify new genes from two conditioned populations.
Synthesis and X-ray diffraction data of 1-N-(4-pyridylmethyl)amino naphthalene
Authors: Camargo H. A. , Henao J. A. , Amado D. F. , Kouznetsov V. V.
Published: March 2010

1-N-(4-pyridylmethyl)amino naphtalene was synthesized by means of a reaction of alpha-naphthylamine, 4-pyridylcarboxyaldehyde, in anhydrous ethanol to obtainN-(4-pyridylen)-alpha-naphthylamine and that was reduced with NaBH4 to produce the wanted compound. The X-ray powder diffraction pattern for the new compound 1-N-(4-pyrydylmethyl)amino naphtalene was obtained. This compound crystallizes in a monoclinic system with refined unit cell parameters a=10.375(5) Å, b=17.665(6) Å, c=5.566(2) Å, β=100.11(3), and V=1004.3(5) Å3, with space group P2/m (No. 10).
Determination of equilibrium transformation temperatures Ae3 and Ae1 for low-carbon steels using the in situ high-temperature X-ray diffraction technique
Authors: Equihua F. , Salinas A.
Published: March 2010

This paper describes a method to determine the equilibrium transformation temperatures in low C steels using the in situ high-temperature X-ray diffraction technique. The samples were heated and then cooled from 1000 to 720 °C in a stepwise manner decreasing to −10 °C. Austenite and ferrite fractions were determined by a quantitative method using the integrated intensities of austenite (111)γ and ferrite (110)α peaks from X-ray diffraction patterns. The effect of the temperature on interplanar d spacings of (111) and (110) crystallographic planes was determined using 2θ maximum positions of the austenite (111)γ and ferrite (110)α peaks. The equilibrium transformation temperatures were determined to be Ae1=720 °C and Ae3=950 °C. The results are in excellent agreement with those obtained by dilatometric analysis and Thermo-Calc phase diagram simulation software. In addition, the results were supported by microstructural observations: the formation of thin ferrite films (5–10 μm) was observed at temperatures near to experimental Ae3.
Powder micro-XRD of small particles
Authors: Swider Joseph R.
Published: March 2010

The increasing use of microanalysis techniques to analyze particles has demanded more rapid phase identification methods for samples in the 10 μm size range. The XRD analysis of such particles is routinely accomplished using a Rigaku combination instrument combined with particle handling methods. Several case studies show the variety of material analysis problems that can be solved with this technique including identification of multiple mineral phases, corrosion components, and paint samples.
Electron density distribution and crystal structure of lithium strontium silicate, Li2SrSiO4
Authors: Hirano Yoshinori , Iwata Tomoyuki , Momma Koichi , Fukuda Koichiro
Published: March 2010

Crystal structure of Li2SrSiO4was reinvestigated by laboratory X-ray powder diffraction. The title compound was trigonal with space groupP3121,Z=3, unit-cell dimensionsa=0.502 281 (4) nm andc=1.245 520(8) nm, andV=0.272 129(3) nm3. The initial structural model was derived by the direct methods and further refined by the Rietveld method. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the structural model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The final reliability indices calculated from MPF wereRwp=8.04%,S=1.22,Rp=6.01%,RB=1.50%, andRF=0.66%. Atomic arrangements of the final structural model were in excellent agreement with the three-dimensional electron-density distributions determined by MPF.
Powder diffraction data of new bismuth yttrium gadolinium oxide, Bi1.8Y0.1Gd0.1O3
Authors: Alizadeh M. , Ahmadi K. , Maghsudipour A.
Published: March 2010

New bismuth yttrium gadolinium oxide, Bi1.8Y0.1Gd0.1O3, synthesized from a stoichiometric mixture of Bi2O3, Y2O3, and Gd2O3, was characterized by X-ray powder diffraction. The compound was determined to be tetragonal, with space group P421c (114), unit-cell parameters of a=7.793 08(29) and c=5.665 71(40) Å, and the number of formulas per unit cell Z=4. Bi1.8Y0.1Gd0.1O3 is isostructural with β-Bi2O3.
Synthesis and crystal structure of a novel hexaborate, Na2ZnB6O11
Authors: Chen Y. Q. , Liang J. K. , Gu Y. X. , Luo J. , Li J. B. , Rao G. H.
Published: March 2010

A novel hexaborate, Na2ZnB6O11, has been successfully synthesized by solid-state reaction and ab initio crystal-structure analysis has been completed using powder X-ray diffraction data. The compound crystallizes in the monoclinic space group Cc with lattice parameters a=10.7329(2) Å b=7.4080(3) Å, c=11.4822(2) Å, and β=112.16(2)°. The number of chemical formula per unit cell is Z=4 and the calculated density is 2.768(3) g/cm3. It represents a new structure type in which double-bridge-ring [B6O11]4− groups were found as fundamental building units. The infrared spectrum confirms the presence of both [BO3]3− groups and [BO4]5− groups.
International Centre for Diffraction Data round robin on quantitative Rietveld phase analysis of pharmaceuticals
Authors: Fawcett T. G. , Needham F. , Faber J. , Crowder C. E.
Published: March 2010

The ICDD sponsored a round robin on the quantitative Rietveld phase analysis of pharmaceuticals. 11 participating laboratories from the pharmaceutical community submitted both raw data and processed quantitative results. The purpose of the round robin was to evaluate current practices in laboratories, so procedures and methods were not specified, but they were recorded. Cluster analysis tools were applied to all the data sets and their use helped identify the root causes of several types of errors in specimen preparation, data treatment, and Rietveld analysis. The authors considered this round robin to be difficult. Sample homogeneity was an issue and molecular orientation was observed in many data sets. Each material studied has structural polymorphs so the selection of starting parameters and their refinement was nontrivial. Similar to prior round robins on inorganic materials and minerals, this round robin identified operator errors as the major contributor to poor results. Four laboratories achieved excellent results on all phases in all three samples, with accuracy within relative errors of 5% to 10%.
Least-squares refinement of biaxial stress components and unit-cell parameter in a 〈111〉 textured cubic TiN polycrystalline thin film by X-ray diffraction
Authors: Yokoyama Ryouichi , Harada Jimpei , Akiniwa Yoshiaki
Published: March 2010

Biaxial residual stress in a 〈111〉 textured cubic TiN polycrystalline thin film was analyzed by linear least-squares refinement using the method proposed by Yokoyama and Harada [J. Appl. Crystallogr. 42, 185–191 (2009)]. Values of the unstressed (or stress-free) unit-cell parameter a0=4.2332±0.0006 Å and the stress components of σ11=397(88), σ22=401(88), and σ12=−110(100) were obtained. The values of the in-plane stresses σ11 and σ22 presented in the TiN film are practically the same, while σ12 is relatively small. The results obtained in this study confirm that the above theoretical prediction by Yokoyama and Harada can be used to obtain reliable values of stress-free unit-cell parameter and three biaxial stress components of a textured cubic thin film.
Internal Loading Distribution in Statically Loaded Ball Bearings Subjected to an Eccentric Thrust Load
Authors: Ricci Mário César
Published: March 2010

Rolling‐element bearings are simple machine elements of great utility used both in simple commercial devices as in complex engineering mechanisms. Because of being a very popular machine element, there is a lot of literature on the subject. With regard to the behavior of internal loading distribution, elastic deformations at point or line contacts, and geometric parameters under loading, although there are many works describing the parameters variation models, few works show such variations in practice, even under simple static loadings. In an attempt to cover this gap some studies are being developed in parallel. Particularly in this work, anew, iterative computational procedure is introduced which calculates internal normal ball loads in statically loaded single‐row, angular‐contact ball bearings, subjected to a known thrust load which is applied to a variable distance (lever arm or eccentricity) from the geometric bearing center line. Numerical examples results for a 218 angular‐contact ball bearing have been compared with those from the literature. Fifty figures are presented showing geometrical features and the following parameters variations as functions of the thrust load and eccentricity: contact angle, contact ellipse parameters, normal ball loads, distances between groove curvature centers, normal and axial deflections, and loading zones.