bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpretation of the dosimetric results of three uniformity regularization methods in terms of expected treatment outcome
Authors: Mavroidis Panayiotis , Komisopoulos Georgios , Lind Bengt K. , Papanikolaou Nikos
Published: November 2008

In IMRT treatment plan optimization there are various methods that try to regularize the variation of dose nonuniformity using purely dosimetric measures. However, although these methods can help in finding a good dose distribution, they do not provide any information regarding the expected treatment outcome. When a treatment plan optimization is performed using biological measures, the final goal should be some indication about the expected tumor control or normal tissue complications, which is the primary goal of treatment planning (the association of treatment configurations and dose prescription with the treatment outcome). In this study, this issue is analyzed distinguishing the dose‐oriented treatment plan optimization from the response‐oriented optimization. Three different dose distributions were obtained by using a dose‐based optimization technique, an EUD‐based optimization without applying any technique for regularizing the nonuniformity of the dose distribution, and an EUD‐based optimization using a variational regularization technique, which controls dose nonuniformity. The clinical effectiveness of the three dose distributions was investigated by calculating the response probabilities of the tumors and organs‐at‐risk (OARs) involved in two head and neck and prostate cancer cases. The radiobiological models used are the linear‐quadratic‐Poisson and the Relative Seriality models. Furthermore, the complication‐free tumor control probability and the biologically effective uniform dose were used for treatment plan evaluation and comparison. The radiobiological comparison shows that the EUD‐based optimization using ‐curve regularization gives better results than the EUD‐based optimization without regularization and dose‐based optimization in both clinical cases. Concluding, it appears that the applied dose nonuniformity regularization technique is expected to improve the effectiveness of the optimized IMRT dose distributions. However, more patient cases are needed to validate the statistical significance of the results and conclusions presented in this paper.
Combining multiple models to generate consensus: Application to radiation‐induced pneumonitis prediction
Authors: Das Shiva K. , Chen Shifeng , Deasy Joseph O. , Zhou Sumin , Yin Fang‐Fang , Marks Lawrence B.
Published: November 2008

The fusion of predictions from disparate models has been used in several fields to obtain a more realistic and robust estimate of the “ground truth” by allowing the models to reinforce each other when consensus exists, or, conversely, negate each other when there is no consensus. Fusion has been shown to be most effective when the models have some complementary strengths arising from different approaches. In this work, we fuse the results from four common but methodologically different nonlinear multivariate models (Decision Trees, Neural Networks, Support Vector Machines, Self‐Organizing Maps) that were trained to predict radiation‐induced pneumonitis risk on a database of 219 lung cancer patients treated with radiotherapy (34 with Grade postradiotherapy pneumonitis). Each model independently incorporated a small number of features from the available set of dose and nondose patient variables to predict pneumonitis; no two models had all features in common. Fusion was achieved by simple averaging of the predictions for each patient from all four models. Since a model's prediction for a patient can be dependent on the patient training set used to build the model, the average of several different predictions from each model was used in the fusion (predictions were made by repeatedly testing each patient with a model built from different cross‐validation training sets that excluded the patient being tested). The area under the receiver operating characteristics curve for the fused cross‐validated results was 0.79, with lower variance than the individual component models. From the fusion, five features were extracted as the consensus among all four models in predicting radiation pneumonitis. Arranged in order of importance, the features are (1) chemotherapy; (2) equivalent uniform dose (EUD) for exponent to 3; (3) EUD for to 1.2, lung volume receiving ; (4) female sex; and (5) squamous cell histology. To facilitate ease of interpretation and prospective use, the fused outcome results for the patients were fitted to a logistic probability function.
Dosimetric verification of helical tomotherapy for total scalp irradiation
Authors: Hardcastle Nicholas , Soisson Emilie , Metcalfe Peter , Rosenfeld Anatoly B. , Tomé Wolfgang A.
Published: November 2008

Total scalp irradiation is a treatment technique used for a variety of superficial malignancies. Helical tomotherapy is an effective technique used for total scalp irradiation. Recent published work has shown the TomoTherapy planning system to overestimate the superficial dose. In this study, the superficial doses for a helical tomotherapy total scalp irradiation have been measured on an anthropomorphic phantom using radiochromic and radiographic film as well as a new skin dosimeter, the MOSkin. The superficial dose was found to be accurately calculated by the TomoTherapy planning system. This is in contrast to recent reports, probably due to a combination of the smaller dose grid resolution used in planning and this particular treatment primarily consisting of beamlets tangential to the scalp. The superficial dose was found to increase from and over the first depth in the phantom in selected regions of the PTV, measured with radiochromic film. The prescription dose was . The superficial dose was at the prescription dose or higher in some regions due to the bolus effect of the thermoplastic head mask and the head rest used to aid treatment setup. It is suggested that to achieve the prescription dose at the surface ( depth) bolus or a custom thermoplastic helmet is used.
Load and resistance factor design of shallow foundations against bearing failure
Authors: Fenton Gordon A. , Griffiths D. V. , Zhang Xianyue
Published: November 2008

Shallow foundation designs are typically governed either by settlement, a serviceability limit state, or by bearing capacity, an ultimate limit state. While geotechnical engineers have been designing against these limit states for over half a century, it is only recently that they have begun to migrate towards reliability-based designs. At the moment, reliability-based design codes are generally derived through calibration with traditional working stress designs. To take advantage of the full potential of reliability-based design the profession must go beyond calibration and take geotechnical uncertainties into account in a rational fashion. This paper proposes a load and resistance factor design (LRFD) approach for the bearing capacity design of a strip footing, using load factors as specified by structural codes. The resistance factors required to achieve an acceptable failure probability are estimated as a function of the spatial variability of the soil and by the level of “understanding” of the soil properties in the vicinity of the foundation. The analytical results, validated by simulation, are primarily intended to aid in the development of the next generation of reliability-based geotechnical design codes, but can also be used to assess the reliability of current designs.
Numerical model tests of building response to excavation-induced ground movements
Authors: Son Moorak , Cording Edward J.
Published: November 2008

Distortion and damage to masonry and frame structures on shallow foundations subjected to excavation-induced ground movements have been investigated using numerical model tests. The numerical tests were modeled using the two-dimensional (2-D) universal distinct element code (UDEC) version 3.1 in which each masonry unit was modeled as a block, with the contacts between blocks having stiffness and strength characteristics of mortar. The soil was modeled elastically with a stiffness selected to provide the same pressure–displacement relation for the 2-D model as that for the three-dimensional (3-D) foundation condition. To give a justifiable basis for the numerical tests, two physical model tests were simulated numerically, and the results from the numerical tests were compared with those from the physical model tests. The good agreements between the numerical simulations and physical model tests led to extended numerical studies. The studies included the effect of cracking in structures and structural types (brick and frame structures) on the building response, considering soil–structure interaction. The numerical studies indicated that the structural response to excavation-induced ground movements is highly dependent on both cracking in structures and structural types, and therefore their effects should be considered for better assessing the building response to excavation-induced ground movements.
TWO-DIMENSIONAL D- DONOR IN A STRONG MAGNETIC FIELD
Authors: ZHANG XIAOYAN , FAN GUOLIANG , WANG JINFENG
Published: November 2008

Two-dimensional negative donor ion in magnetic fields are investigated. Using a variational method, we calculated the binding energies of D- center for the spin-triplet states of L = -2 and L = -3 in this structure. The threshold values of the magnetic field which turn unbound state into bound state were obtained.
FIRST PRINCIPLES NON-COLLINEAR TRANSPORT CALCULATION AND INTERFACIAL SPIN-FLIPPING OF Cu/Co MULTILAYERS
Authors: TANG LING , WANG SHUAI
Published: November 2008

In this paper, the first principle non-collinear transport calculation for Cu/Co (111) including interfacial spin-flipping was performed. We modeled spin-flipping at the interface by assuming a non-collinear magnetic structure with random magnetization orientation which satisfied the Gaussian distribution along the average magnetization direction. The relationship between spin-dependent conductance including interfacial spin-flipping and random magnetization orientation distribution width was obtained. For certain distribution width, our defined spin-flipping ratio coincides with the range of experimental spin-flipping probability P = 1-e-δ, where δ = 0.25±0.1. The magnetoresistance in the Co/Cu/Co spin-valve system including interfacial spin-flipping has also been calculated.
A Biologically Plausible Computational Model for Auditory Object Recognition
Authors: Larson Eric , Billimoria Cyrus P. , Sen Kamal
Published: November 2008

Object recognition is a task of fundamental importance for sensory systems. Although this problem has been intensively investigated in the visual system, relatively little is known about the recognition of complex auditory objects. Recent work has shown that spike trains from individual sensory neurons can be used to discriminate between and recognize stimuli. Multiple groups have developed spike similarity or dissimilarity metrics to quantify the differences between spike trains. Using a nearest-neighbor approach the spike similarity metrics can be used to classify the stimuli into groups used to evoke the spike trains. The nearest prototype spike train to the tested spike train can then be used to identify the stimulus. However, how biological circuits might perform such computations remains unclear. Elucidating this question would facilitate the experimental search for such circuits in biological systems, as well as the design of artificial circuits that can perform such computations. Here we present a biologically plausible model for discrimination inspired by a spike distance metric using a network of integrate-and-fire model neurons coupled to a decision network. We then apply this model to the birdsong system in the context of song discrimination and recognition. We show that the model circuit is effective at recognizing individual songs, based on experimental input data from field L, the avian primary auditory cortex analog. We also compare the performance and robustness of this model to two alternative models of song discrimination: a model based on coincidence detection and a model based on firing rate.
PPARδ Agonism for the Treatment of Obesity and Associated Disorders: Challenges and Opportunities
Authors: Perreault Mylène , Erbe David V. , Tobin James F.
Published: November 2008

The prevalence of obesity in the USA and worldwide has reached epidemic proportions during the last two decades. Drugs currently available for the treatment of obesity provide no more than 5% placebo‐adjusted weight loss and are associated with undesirable side effects. Peroxisome proliferator‐activated receptor (PPAR) modulators offer potential benefits for the treatment of obesity and its associated complications but their development has been complicated by biological, technical, and regulatory challenges. Despite significant challenges, PPAR modulators are attractive targets for the treatment of obesity and could offer a viable alternative to the millions of patients who fail to lose weight following rigorous dieting and exercise protocols. In addition, PPAR modulators have the potential‐added benefit of ameliorating the associated comorbidities.
Single Nucleotide Polymorphisms in Selected Apoptotic Genes and BPDE-Induced Apoptotic Capacity in Apparently Normal Primary Lymphocytes: A Genotype-Phenotype Correlation Analysis
Authors: Hu Zhibin , Li Chunying , Chen Kexin , Wang Li-E , Sturgis Erich M. , Spitz Margaret R. , Wei Qingyi
Published: November 2008

Apoptotic capacity (AC) in primary lymphocytes may be a marker for cancer susceptibility, and functional single nucleotide polymorphisms (SNPs) in genes involved in apoptotic pathways may modulate cellular AC in response to DNA damage. To further examine the correlation between apoptotic genotypes and phenotype, we genotyped 14 published SNPs in 11 apoptosis-related genes (i.e.,p53, Bcl-2, BAX, CASP9, DR4, Fas, FasL, CASP8, CASP10, CASP3, andCASP7) and assessed the AC in response to benzo[a]pyrene-7,8-9,10-diol epoxide (BPDE) in cultured primary lymphocytes from 172 cancer-free subjects. We found that among these 14 SNPs, R72P, intron 3 16-bp del/ins, and intron 6 G>A inp53, −938C>A inBcl-2, and I522L inCASP10were significant predictors of the BPDE-induced lymphocytic AC in single-locus analysis. In the combined analysis of the threep53variants, we found that the individuals with the diplotypes carrying 0-1 copy of the commonp53R-del-G haplotype had higher AC values compared to other genotypes. Although the study size may not have the statistical power to detect the role of other SNPs in AC, our findings suggest that some SNPs in genes involved in the intrinsic apoptotic pathway may modulate lymphocytic AC in response to BPDE exposure in the general population. Larger studies are needed to validate these findings for further studying individual susceptibility to cancer and other apoptosis-related diseases.
Adult Urethral Stricture Disease after Childhood Hypospadias Repair
Authors: Tang Shou-Hung , Hammer Clarisa C. , Doumanian Leo , Santucci Richard A.
Published: November 2008

Background. Adult patients with urethral stricture after childhood hypospadias surgeries are infrequently discussed in the literature. We report our experience in treating such patients.Materials and Methods. A retrospective chart review was performed. From 2002 through 2007, nine consecutive adult patients who had current urethral stricture and had undergone childhood hypospadias surgeries were included. All adult urethral strictures were managed by a single surgeon.Results. Mean patient age was 38.9 years old. The lag time of urethral stricture presentation ranged from 25 to 57 years after primary hypospadias surgery, with an average of 36 years. Stricture length ranged from 1 to 17 cm (mean: 10.3 cm). Open graft-based urethroplasties were performed in 4/9 cases. Salvage perineal urethrostomy was performed in 2/9 cases. Another 3 cases chose to undergo repeat urethrotomy or dilatations—none of these patients was cured by such treatment. Complications included one urethrostomy stenosis and one urinary tract infection.Conclusion. Urethral stricture may occur decades after initial hypospadias surgery. It can be the most severe form of anterior urethral stricture, and may eventually require salvage treatment such as a perineal urethrostomy. Patients undergoing hypospadias surgery should receive lifelong follow-up protocol to detect latent urethral strictures.
High‐Efficiency Intracavity Continuous‐Wave Green‐Light Generation by Quasiphase Matching in a Bulk Periodically Poled MgO:LiNbO3 Crystal
Authors: Chu Shaowei , Zhang Ying , Wang Bin , Bi Yong
Published: November 2008

908 mW of green light at 532 nm were generated by intracavity quasiphase matching in a bulk periodically poled MgO:LiNbO3 (PPMgLN) crystal. A maximum optical‐to‐optical conversion efficiency of 33.5% was obtained from a 0.5 mm thick, 10 mm long, and 5 mol% MgO:LiNbO3 crystal with an end‐pump power of 2.7 W at 808 nm. The temperature bandwidth between the intracavity and single‐pass frequency doubling was found to be different for the PPMgLN. Reliability and stability of the green laser were evaluated. It was found that for continuous operation of 100 hours, the output stability was better than 97.5% and no optical damage was observed.
Traffic and Quality Characterization of the H.264/AVC Scalable Video Coding Extension
Authors: Van der Auwera Geert , David Prasanth T. , Reisslein Martin , Karam Lina J.
Published: November 2008

The recent scalable video coding (SVC) extension to the H.264/AVC video coding standard has unprecedented compression efficiency while supporting a wide range of scalability modes, including temporal, spatial, and quality (SNR) scalability, as well as combined spatiotemporal SNR scalability. The traffic characteristics, especially the bit rate variabilities, of the individual layer streams critically affect their network transport. We study the SVC traffic statistics, including the bit rate distortion and bit rate variability distortion, with long CIF resolution video sequences and compare them with the corresponding MPEG‐4 Part 2 traffic statistics. We consider (i) temporal scalability with three temporal layers, (ii) spatial scalability with a QCIF base layer and a CIF enhancement layer, as well as (iii) quality scalability modes FGS and MGS. We find that the significant improvement in RD efficiency of SVC is accompanied by substantially higher traffic variabilities as compared to the equivalent MPEG‐4 Part 2 streams. We find that separately analyzing the traffic of temporal‐scalability only encodings gives reasonable estimates of the traffic statistics of the temporal layers embedded in combined spatiotemporal encodings and in the base layer of combined FGS‐temporal encodings. Overall, we find that SVC achieves significantly higher compression ratios than MPEG‐4 Part 2, but produces unprecedented levels of traffic variability, thus presenting new challenges for the network transport of scalable video.
Domain‐Reversed Lithium Niobate Single‐Crystal Fibers are Potentially for Efficient Terahertz Wave Generation
Authors: Lu Yalin , Reinhardt Kitt
Published: November 2008

Nonlinear frequency conversion remains one of the dominant approaches to efficiently generate THz waves. Significant material absorption in the THz range is the main factor impeding the progress towards this direction. In this research, a new multicladding nonlinear fiber design was proposed to solve this problem, and as the major experimental effort, periodic domain structure was introduced into lithium niobate single‐crystal fibers by electrical poling. The introduced periodic domain structures were nondestructively revealed using a crossly polarized optical microscope and a confocal scanning optical microscope for quality assurance.
An Analysis of X‐Band Calibrated Sea Clutter and Small Boat Reflectivity at Medium‐to‐Low Grazing Angles
Authors: Herselman P. L. , Baker C. J. , de Wind H. J.
Published: November 2008

The coherent temporal characteristics of
medium‐to‐low grazing angle sea clutter and small boat reflectivity
are considered for different radar waveforms under a range
of environmental conditions and geometrical configurations. Accurate
empirical modelling of sea clutter enables the inference
of the local sea conditions from radar returns, pertinent for
port safety and navigation. Understanding the dynamics and
associated reflectivity of small boats, in addition to empirical
sea clutter models, allows the development of advanced detection
and tracking algorithms, which will improve the performance of
surveillance and marine navigation radar against small boats.
Work presented is based on the empirical analysis of data
recorded with two calibrated, coherent, pulsed radar systems at
X‐band frequencies. Specifically, target echoes from small boats
are included in the datasets and subsequent analysis.
Genomic Promoter Analysis Predicts Functional Transcription Factor Binding
Authors: Rao J. Sunil , Karanam Suresh , McCabe Colleen D. , Moreno Carlos S.
Published: November 2008

Background. The computational identification of functional transcription factor binding sites (TFBSs) remains a major challenge of computational biology.Results. We have analyzed the conserved promoter sequences for the complete set of human RefSeq genes using our conserved transcription factor binding site (CONFAC) software. CONFAC identified 16296 human‐mouse ortholog gene pairs, and of those pairs, 9107 genes contained conserved TFBS in the 3 kb proximal promoter and first intron. To attempt to predict in vivo occupancy of transcription factor binding sites, we developed a novel marginal effect isolator algorithm that builds upon Bayesian methods for multigroup TFBS filtering and predicted the in vivo occupancy of two transcription factors with an overall accuracy of 84%.Conclusion. Our analyses show that integration of chromatin immunoprecipitation data with conserved TFBS analysis can be used to generate accurate predictions of functional TFBS. They also show that TFBS cooccurrence can be used to predict transcription factor binding to promoters in vivo.
Permanence of Periodic Predator‐Prey System with Functional Responses and Stage Structure for Prey
Authors: Huang Can-Yun , Zhao Min , Huo Hai-Feng
Published: November 2008

A stage‐structured three‐species predator‐prey model with Beddington‐DeAngelis and Holling II functional response is introduced. Based on the comparison theorem, sufficient and necessary conditions which guarantee the predator and the prey species to be permanent are obtained. An example is also presented to illustrate our main results.
Conserved Microsynteny ofNPR1with Genes Encoding a Signal Calmodulin-Binding Protein and a CK1-Class Protein Kinase inBeta vulgarisand Two Other Eudicots
Authors: Kuykendall David , Shao Jonathan , Murphy Tammy
Published: November 2008

NPR1is a gene of central importance in enabling plants to resist microbial attack. Therefore, knowledge of nearby genes is important for genome analysis and possibly for improving disease resistance. In this study, systematic DNA sequence analysis, gene annotation, and protein BLASTs were performed to determine genes near theNPR1gene inBeta vulgarisL.,Medicago truncatulaGaertn, andPopulus trichocarpaTorr. & Gray, and to access predicted function. Microsynteny was discovered forNPR1with genesCaMP, encoding a chloroplast-targeted signal calmodulin-binding protein, andCK1PK, a CK1-class protein kinase. Conserved microsynteny ofNPR1,CaMP, andCK1PKin three diverse species of eudicots suggests maintenance during evolution by positive selection for close proximity. Perhaps close physical linkage contributes to coordinated expression of these particular genes that may control critically important processes including nuclear events and signal transduction.
Formation of MgO:LiNbO3 Domain‐Inverted Gratings by Voltage Application under UV Light Irradiation at Room Temperature
Authors: Fujimura Masatoshi , Suhara Toshiaki
Published: November 2008

MgO:LiNbO3 is an attractive nonlinear‐optic crystal for quasiphasematched (QPM) nonlinear‐optic devices. This paper reports a new formation method of domain‐inverted gratings for QPM in MgO:LiNbO3. Domain inversion of MgO:LiNbO3 by voltage application under UV light was characterized, and reduction of the voltage required for inversion was demonstrated. Results of voltage application under periodic UV light suggested that suppression of excess lateral expansion of the domain inverted regions on −Z surface was crucial for domain‐inverted grating formation. Voltage application to a crystal with a photoconductive cladding layer under periodic UV light was proposed. The cladding layer suppressed the expansion, and the domain‐inverted gratings with period of 18 μm and area of 25 × 5
 mm2 were obtained. The formation method does not require the photolithography process and allows the formation by voltage application at room temperature, and therefore, is quite simple and productive.
Noise Analysis of Second‐Harmonic Generation in Undoped and MgO‐Doped Periodically Poled Lithium Niobate
Authors: Wang Yong , Fonseca-Campos Jorge , Liang Wan-guo , Xu Chang-Qing , Vargas-Baca Ignacio
Published: November 2008

Noise characteristics of second‐harmonic generation (SHG) in
periodically poled lithium niobate (PPLN) using the quasiphase
matching (QPM) technique are analyzed experimentally. In the
experiment, a0.78 μm second‐harmonic (SH) wave was generated when
a 1.56 μm fundamental wave passed through a PPLN crystal (bulk or
waveguide). The time‐domain and frequency‐domain noise
characteristics of the fundamental and SH waves were analyzed. By
using the pump‐probe method, the noise characteristics of SHG were
further analyzed when a visible light (532 nm) and an infrared
light (1090 nm) copropagated with the fundamental light,
respectively. The noise characterizations were also investigated
at different temperatures. It is found that for the bulk and
waveguide PPLN crystals, the SH wave has a higher relative noise
level than the corresponding fundamental wave. For the same
fundamental wave, the SH wave has lower noise in a bulk crystal
than in a waveguide, and in MgO‐doped PPLN than in undoped PPLN.
The 532 nm irradiation can lead to higher noise in PPLN than the
1090 nm irradiation. In addition, increasing temperature of device
can alleviate the problem of noise in conjunction with the
photorefractive effect incurred by the irradiation light. This is
more significant in undoped PPLN than in MgO‐doped one.
Best Proximity Pairs Theorems for Continuous Set-Valued Maps
Authors: Amini-Harandi A. , Farajzadeh A. P. , O'Regan D. , Agarwal R. P.
Published: November 2008

A best proximity pair for a set-valued map "Equation missing" with respect to a set-valued map "Equation missing" is defined, and a new existence theorem of best proximity pairs for continuous set-valued maps is proved in nonexpansive retract metric spaces. As an application, we derive a coincidence point theorem.
Conceptualizing Human Microbiota: From Multicelled Organ to Ecological Community
Authors: Foxman Betsy , Goldberg Deborah , Murdock Courtney , Xi Chuanwu , Gilsdorf Janet R.
Published: November 2008

The microbiota of a typical, healthy human contains 10 times as many cells as the human body and incorporates bacteria, viruses, archea, protozoans, and fungi. This diverse microbiome (the collective genomes of the microbial symbionts that inhabit a human host) is essential for human functioning. We discuss the unstated assumptions and implications of current conceptualizations of human microbiota: (1) a single unit that interacts with the host and the external environment; a multicelled organ; (2) an assemblage of multiple taxa, but considered as a single unit in its interactions with the host; (3) an assemblage of multiple taxa, which each interacts with the host and the environment independently; and (4) a dynamic ecological community consisting of multiple taxa each potentially interacting with each other, the host, and the environment. Each conceptualization leads to different predictions, methodologies, and research strategies.
Primary Mesenteric Sertoli-Leydig Cell Tumor: A Case Report and Review of the Literature
Authors: Trabelsi Amel , Ben Abdelkarim Soumaya , Hadfi Mohamed , Fatnaci Ridha , Stita Wided , Sriha Badreddine , Korbi Sadok
Published: November 2008

The occurrence of primary sex cord-stromal tumors at extraovarian sites is exceedingly rare. We report a new case of Sertoli-Leydig cell tumor in the mesentery of a 78-year-old woman who presented with occlusive syndrome and reviewed the previously reported cases of extraovarian sex cord-stromal tumors in the English literature.
Interactions of the Intestinal Epithelium with the Pathogen and the Indigenous Microbiota: A Three-Way Crosstalk
Authors: Srikanth C. V. , McCormick Beth A.
Published: November 2008

The mucosal surfaces of the gastrointestinal tract harbor a vast number of commensal microbiota that have coevolved with the host, and in addition display one of the most complex relationships with the host. This relationship affects several important aspects of the biology of the host including the synthesis of nutrients, protection against infection, and the development of the immune system. On the other hand, despite the existence of several lines of mucosal defense mechanisms, pathogenic organisms such as Shigella and Salmonella have evolved sophisticated virulence strategies for breaching these barriers. The constant challenge from these pathogens and the attempts by the host to counter them set up a dynamic equilibrium of cellular and molecular crosstalk. Even slight perturbations in this equilibrium may be detrimental to the host leading to severe bacterial infection or even autoimmune diseases like inflammatory bowel disease. Several experimental model systems, including germ-free mice and antibiotic-treated mice, have been used by various researchers to study this complex relationship. Although it is only the beginning, it promises to be an exciting era in the study of these host-microbe relationships.
Intermediate Inflation or Late Time Acceleration?
Authors: Sanyal Abhik Kumar
Published: November 2008

The expansion rate of “intermediate inflation” lies between the exponential and power law expansion but
corresponding accelerated expansion does not start at the onset of cosmological evolution. Present study of
“intermediate inflation” reveals that it admits scaling solution and has got a natural exit form it at a later
epoch of cosmic evolution, leading to late time acceleration. The corresponding scalar field responsible for such
feature is also found to behave as a tracker field for gravity with canonical kinetic term.
Hypospadias
Authors: Djakovic N. , Nyarangi-Dix J. , Özturk A. , Hohenfellner M.
Published: November 2008

Objective. The great possibility of variations in the clinical presentation of hypospadia, makes its therapy challenging. This has led to the development of a number of techniques for hypospadia repair. This article assesses past and present concepts and operative techniques with the aim of broadening our understanding of this malformation.Materials and Methods. The article not only reviews hypospadia in general with its development and clinical presentation as well as historical and current concepts in hypospadiologie on the basis of available literature, but it is also based on our own clinical experience in the repair of this malformation.Results and Conclusion. The fact that there are great variations in the presentation and extent of malformations existent makes every hypospadia individual and a proposal of a universal comprehensive algorithm for hypospadia repair difficult. The Snodgrass technique has found wide popularity for the repair of distal hypospadias. As far as proximal hypospadias are concerned, their repair is more challenging because it not only involves urethroplasty, but can also, in some cases, fulfil the dimensions of a complex genital reconstruction. Due to the development of modern operating materials and an improvement in current surgical techniques, there has been a significant decrease in the complication rates. Nonetheless, there still is room and, therefore, need for further improvement in this field.
The Role of the PAX8/PPARγ Fusion Oncogene in Thyroid Cancer
Authors: Placzkowski Kimberly A. , Reddi Honey V. , Grebe Stefan K. G. , Eberhardt Norman L. , McIver Bryan
Published: November 2008

Thyroid cancer is uncommon and exhibits relatively low mortality rates. However, a subset of patients experience inexorable growth, metastatic spread, and mortality. Unfortunately, for these patients, there have been few significant advances in treatment during the last 50 years. While substantial advances have been made in recent years about the molecular genetic events underlying papillary thyroid cancer, the more aggressive follicular thyroid cancer remains poorly understood. The recent discovery of the PAX8/PPARγ translocation in follicular thyroid carcinoma has promoted progress in the role of PPARγ as a tumor suppressor and potential therapeutic target. The PAX8/PPARγ fusion gene appears to be an oncogene. It is most often expressed in follicular carcinomas and exerts a dominant‐negative effect on wild‐type PPARγ, and stimulates transcription of PAX8‐responsive promoters. PPARγ agonists have shown promising results in vitro, although very few studies have been conducted to assess the clinical impact of these agents.
Male Genitoplasty for Intersex Disorders
Authors: Sharma Shilpa , K. Gupta Devendra
Published: November 2008

Aim. To evaluate surgical procedures adopted for male genitoplasty in intersex disorders.Patients and Methods. Case records of intersex patients undergoing male genitoplasty from Pediatric Intersex clinic were studied.Results. Of 356 intersex cases undergoing urethroplasty from 1989–2007, the hypospadias was penoscrotal (68%), scrotal (17%) and perineal (15%). 351 patients underwent chordee correction for mild: moderate: severe chordee in 24 : 136 : 191 cases. Byars flaps were fixed upto the corona in 267 cases. Urethroplasty performed was Theirsch duplay in 335 cases, Snodgrass in 16 cases and Ducketts onlay graft in 5 cases that did not require chordee correction. Age at urethroplasty was 2.5 years—22 years (mean 11.5 years, median—5.6 years). Penoscrotal transposition correction and testicular prosthesis insertion were performed independently. Complications included fistula (45), recurrent fistula (11), stricture (12), baggy urethra (8) and recurrent infection due to persistent vaginal pouch (5). Additional distal urethroplasty was required in 15 patients for previous urethroplasty done upto the corona 5–15 years earlier.Conclusion. Hypospadias in intersex disorders is associated with severe chordee in most cases and requires an early chordee correction to allow phallic growth, staged urethroplasty and multiple surgeries to achieve good cosmetic and functional results.
On Nonperturbative Techniques for Thermal Radiation Effect on Natural Convection past a Vertical Plate Embedded in a Saturated Porous Medium
Authors: Makinde O. D. , Moitsheki R. J.
Published: November 2008

In this article, the heat transfer characteristics of natural convection about a vertical permeable flat surface embedded in a saturated porous medium are studied by taking into account the thermal radiation effect. The plate is assumed to have a power‐law temperature distribution. Similarity variables are employed in order to transform the governing partial differential equations into a nonlinear ordinary differential equation. Both Adomian decomposition method (ADM) and He′s variational iteration method (VIM) coupled with Padé approximation technique are implemented to solve the reduced system. Comparisons with previously published works are performed, and excellent agreement between the results is obtained.
Phase Velocity Estimation of a Microstrip Line in a Stoichiometric Periodically Domain‐Inverted LiTaO3 Modulator Using Electro‐Optic Sampling Technique
Authors: Hisatake Shintaro , Kaino Akira , Yasuda Tomoaki , Nagatsuma Tadao
Published: November 2008

We estimate the phase velocity of a modulation microwave in a
quasi‐velocity‐matched (QVM) electro‐optic (EO) phase modulator
(QVM‐EOM) using EO sampling which is accurate and the most reliable
technique for measuring voltage waveforms at an electrode. The
substrate of the measured QVM‐EOM is a stoichiometric periodically
domain‐inverted LiTaO3 crystal. The electric field of a standing wave
in a resonant microstrip line (width: 0.5 mm, height: 0.5 mm) is measured by
employing a CdTe crystal as an EO sensor. The wavelength of the traveling
microwave at 16.0801 GHz is determined as 3.33 mm by fitting the theoretical
curve to the measured electric field distribution. The phase velocity is
estimated as vm = 5.35 × 107 m/s, though there exists
about 5% systematic error due to the perturbation by the EO sensor.
Relative dielectric constant of εr = 41.5 is led as the maximum
likelihood value that derives the estimated phase velocity.
Surface Chemical Modification of Multiwalled Carbon Nanotubes by a Wet‐Mechanochemical Reaction
Authors: Chen Lifei , Xie Huaqing , Li Yang , Yu Wei
Published: November 2008

A wet‐mechanochemical reaction for surface modification of multiwalled carbon nanotubes (CNTs) has been developed. In the treatment, CNTs reacted with potassium hydroxide in alcohol solvent at room temperature under mechanical milling. The results from Fourier transmission infrared spectroscopy demonstrate that the nonreactive surfaces of CNTs have been modified successfully by multiple hydroxyl groups. Functionalized carbon nanotubes exhibit higher zeta potential values indicating their high dispersibility in polar solvents. XRD studies corroborate that the surface functionalization does not affect the basic crystal domain size of CNTs. TEM observations reveal that CNTs have been cut into shorter ones by the milling. Shortened CNTs with functionalized surfaces show good dispersion properties.
Application of Ecological Network Theory to the Human Microbiome
Authors: Foster James A. , Krone Stephen M. , Forney Larry J.
Published: November 2008

In healthy humans, many microbial consortia constitute rich ecosystems with dozens to hundreds of species, finely tuned to functions relevant to human health. Medical interventions, lifestyle changes, and the normal rhythms of life sometimes upset the balance in microbial ecosystems, facilitating pathogen invasions or causing other clinically relevant problems. Some diseases, such as bacterial vaginosis, have exactly this sort of community etiology. Mathematical network theory is ideal for studying the ecological networks of interacting species that comprise the human microbiome. Theoretical networks require little consortia specific data to provide insight into both normal and disturbed microbial community functions, but it is easy to incorporate additional empirical data as it becomes available. We argue that understanding some diseases, such as bacterial vaginosis, requires a shift of focus from individual bacteria to (mathematical) networks of interacting populations, and that known emergent properties of these networks will provide insights that would be otherwise elusive.
Mechanical and Thermal Properties of Poly(urethane urea) Nanocomposites Prepared with Diamine‐Modified Laponite
Authors: Sormana Joe-Lahai , Chattopadhyay Santanu , Meredith J. Carson
Published: November 2008

Nanocomposites based on segmented poly(urethane urea) were prepared by reacting a poly(diisocyanate) with diamine‐modified Laponite‐RD nanoparticles that served as a chain extender. The nanocomposites were prepared at a constant NH2 to NCO mole ratio of 0.95, while varying the fraction of diamine‐modified Laponite relative to the free diamine chain extender. Compared to neat poly(urethane urea), all nanocomposites showed increased tensile strength and elongation at break. As Laponite loading increased, tensile properties passed through a maximum at a particle concentration of 1 mass%, at which a 300% increase in tensile strength and 40% increase in elongation at break were observed. A maximum in urea and urethane hard‐domain melting endotherms was also observed at this Laponite loading. Optimal mechanical and thermal properties coincided with a minimum in the size of the inorganic Laponite phase. Nanocomposites containing diamine‐modified Laponite had higher tensile strengths than those with nonreactive monoamine‐modified Laponite or diamine‐modified Cloisite.
The Role of NMDA Receptor Subtypes in Short-Term Plasticity in the Rat Entorhinal Cortex
Authors: Chamberlain Sophie E. L. , Yang Jian , Jones Roland S. G.
Published: November 2008

We have previously shown that spontaneous release of glutamate in the entorhinal cortex (EC) is tonically facilitated via activation of presynaptic NMDA receptors (NMDAr) containing the NR2B subunit. Here we show that the same receptors mediate short-term plasticity manifested by frequency-dependent facilitation of evoked glutamate release at these synapses. Whole-cell patch-clamp recordings were made from layer V pyramidal neurones in rat EC slices. Evoked excitatory postsynaptic currents showed strong facilitation at relatively low frequencies (3 Hz) of activation. Facilitation was abolished by an NR2B-selective blocker (Ro 25-6981), but unaffected by NR2A-selective antagonists (Zn2+, NVP-AAM077). In contrast, postsynaptic NMDAr-mediated responses could be reduced by subunit-selective concentrations of all three antagonists. The data suggest that NMDAr involved in presynaptic plasticity in layer V are exclusively NR1/NR2B diheteromers, whilst postsynaptically they are probably a mixture of NR1/NR2A, NR1/NR2B diheteromers and NR1/NR2A/NR2B triheteromeric receptors.
Electrooptic Modulators with Controlled Frequency Responses by Using Nonperiodically Polarization‐Reversed Structure
Authors: Pham Ha Viet , Murata Hiroshi , Okamura Yasuyuki
Published: November 2008

We discuss a new method to design traveling‐wave electrooptic modulators with controlled frequency responses using nonperiodically polarization‐reversed structure. Using our method, the frequency responses of both magnitude and phase of modulation index are controllable. Several electrooptic modulators for advanced modulation formats such as duobinary modulation and wideband single‐sideband modulation are proposed.
Negative Refraction Using Frequency‐Tuned Oxide Multilayer Structure
Authors: Lu Yalin , Brown Gail J. , Reinhardt Kitt
Published: November 2008

An oxide‐based multilayer structure was proposed to realize negative refraction. The multilayer composes of alternative layers having negative permittivity and negative permeability, respectively. In order to realize negative refraction, their dielectric and magnetic resonances of layers will be tuned to the frequency as close as possibly via changing their temperature, composition, structure, and so forth. Such oxide‐based NIMs are attractive for their potential applications as optical super lenses, imagers, optical cloaking, sensors, and so forth, those are required with low‐loss, low‐cost,
and good fabrication flexibility.
Second Harmonic Generation Using an All‐Fiber Q‐Switched Yb‐Doped Fiber Laser and MgO:c‐PPLN
Authors: Gan Yi , Gu Xijia , Koo Joyce Y. C. , Liang Wanguo , Xu Chang-qing
Published: November 2008

We have experimentally demonstrated an efficient all‐fiber passively Q‐switched Yb‐doped fiber laser with Samarium doped fiber as a saturable absorber. Average output power of 3.4 W at a repetition rate of 250 kHz and a pulse width of 1.1 microseconds was obtained at a pump power of 9.0 W. By using this fiber laser system and an MgO‐doped congruent periodically poled lithium niobate (MgO:c‐PPLN), second harmonic generation (SHG) output at 532 nm was achieved at room temperature. The conversion efficiency is around 4.2% which agrees well with the theoretical simulation.
A Study on Gas Pressure Fluctuation Characteristics inside the Snubber and Pipe of Hydrogen
Authors: Rahman M. Sq. , Lee G. H. , Utomo T. S. , Jeong H. M. , Chung H. S.
Published: November 2008

Hydrogen fuel cell is a developing technology that allows great amount of electrical power to be obtained using a source of hydrogen gas. It is a proven environment-friendly potential future fuel. During compression of hydrogen gas in reciprocating compressor, pressure fluctuation is built up. The pressure fluctuation and its reduction by the snubber are studied in this experiment. For different motor frequencies, the input and output pressure amplitude varies from 0.228 kPa–2.081 kPa and 0.095 kPa–0.898 kPa. The pressure magnitudes are 101.451–105.172 kPa and 101.388–102.565 kPa for input and output of the snubber, respectively. The acryl snubber reduces0.796 kPa (57.31%) pressure amplitude on average with restoring its high pressure. Detail information about the pressure including the critical pressure zone inside the tube like snubber part and the whole system can be obtained by CFD.
Ankyrin Repeat Domain 1, ANKRD1, a Novel Determinant of Cisplatin Sensitivity Expressed in Ovarian Cancer
Authors: Scurr Lyndee L. , Guminski Alexander D. , Chiew Yoke-Eng , Balleine Rosemary L. , Sharma Raghwa , Lei Ying , Pryor Kylie , Wain Gerard V. , Brand Alison , Byth Karen , Kennedy Catherine , Rizos Helen , Harnett Paul R. , deFazio Anna
Published: November 2008

Purpose: The standard of care for ovarian cancer includes platinum-based chemotherapy. It is not possible, however, to predict clinical platinum sensitivity or to design rational strategies to overcome resistance. We used a novel approach to identify altered gene expression associated with high sensitivity to cisplatin, to define novel targets to sensitize tumor cells to platins and ultimately improve the effectiveness of this widely used class of chemotherapeutics.

Experimental Design: Using differential display PCR, we identified genes differentially expressed in a mutagenized cell line with unusual sensitivity to cisplatin. The most highly differentially expressed gene was selected, and its role in determining cisplatin sensitivity was validated by gene transfection and small interfering RNA (siRNA) approaches, by association of expression levels with cisplatin sensitivity in cell lines, and by association of tumor expression levels with survival in a retrospective cohort of 71 patients with serous ovarian adenocarcinoma.

Results: The most highly differently expressed gene identified was ANKRD1, ankyrin repeat domain 1 (cardiac muscle). ANKRD1 mRNA levels were correlated with platinum sensitivity in cell lines, and most significantly, decreasing ANKRD1 using siRNA increased cisplatin sensitivity >2-fold. ANKRD1 was expressed in the majority of ovarian adenocarcinomas tested (62/71, 87%), and higher tumor levels of ANKRD1 were found in patients with worse outcome (overall survival, P = 0.013).

Conclusions: These findings suggest that ANKRD1, a gene not previously associated with ovarian cancer or with response to chemotherapy, is associated with treatment outcome, and decreasing ANKRD1 expression, or function, is a potential strategy to sensitize tumors to platinum-based drugs.