bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of apoptosis regulatory proteins p53 and Bcl‐2 in skin of patients with chronic renal failure on maintenance haemodialysis
Authors: El‐Domyati MM , Ahmad HM , Nagy I , Zahran A
Published: February 2007

Background  Chronic renal failure results in multi‐organ system derangement including cardiovascular, gastrointestinal, neurological, endocrinal, blood and dermatological abnormalities. Maintenance of skin homeostasis requires a delicate balance between proliferation, differentiation and apoptosis. p53 and Bcl‐2 proteins play a central role in the regulation of apoptosis.

Objective  Evaluation of the expression of apoptosis regulatory proteins p53 and Bcl‐2 in apparently normal skin of patients, with chronic renal failure on maintenance haemodialysis, with respect to their role in the apoptotic process.

Methods  Biopsy specimens were obtained from 10 patients with chronic renal failure on maintenance haemodialysis, as well as seven age‐matched control subjects. Computer‐assisted image analysis was employed to measure epidermal thickness in H&E‐stained sections. Immunoperoxidase technique was also used to demonstrate p53 and Bcl‐2 proteins and the TUNEL technique for detection of apoptotic cells in these specimens.

Results  The mean epidermal thickness was significantly higher (P < 0.0001) in patients than controls. Meanwhile, no apoptotic cells were detected in the epidermis of patients. On the other hand, a statistically significant difference was observed in both p53 (P = 0.0001) and Bcl‐2 expression (P = 0.0003) when comparing patients and controls. Expression of p53 (2.74 ± 0.84) and Bcl‐2 (3.45 ± 1.35) proteins was higher in skin samples obtained from patients with chronic renal failure and on maintenance haemodialysis than those from control cases (0.5 ± 0.96 and 0.8 ± 0.6, respectively). Moreover, Bcl‐2 expression in patients was observed in basal as well as squamous cell layers of skin, whereas in control subjects it was confined to the basal cell layer only.

Conclusion  These findings suggest that an alteration in the proliferation/apoptosis balance may be present in the skin of such patients.
Preliminary Results with Percutaneous Transcatheter Microwave Ablation of Typical Atrial Flutter
Authors: CHAN JOSEPH YAT‐SUN , WING‐HONG FUNG JEFFERY , YU CHEUK‐MAN , FELD GREGORY K.
Published: February 2007

Background: Linear microwave ablation has been shown to be effective for treatment of atrial fibrillation during open‐heart surgery by producing transmural lesions in the atrium to isolate the pulmonary veins. However, the safety and efficacy of percutaneous, transcatheter, linear microwave ablation for atrial arrhythmias, while demonstrated in animal models, is unknown in humans. Therefore, we studied the safety and efficacy of linear microwave ablation of the cavotricuspid isthmus (CTI) in humans with typical atrial flutter, utilizing a 2‐cm long microwave antenna mounted on a steerable 9‐French catheter.

Methods and Results: In seven consecutive patients, multielectrode catheters were positioned at the His bundle (quadripolar) and around the TV annulus (duo‐decapolar) for pacing and recording atrial activation sequence before and after ablation. The microwave antenna was withdrawn gradually from tricuspid annulus towards inferior vena cava to ablate the CTI. Intracardiac ultrasound was used to ensure adequate endocardial contact of the microwave ablation catheter with the CTI. Microwave energy was applied at a power of 18 to 21 W at each ablation point for 120 seconds. Ablation was repeated until bidirectional CTI block was confirmed by demonstrating a descending activation wavefront in the contralateral atrial wall during pacing from the coronary sinus ostium or low lateral right atrium, respectively. Bidirectional isthmus block was achieved in all patients, after a mean number of 27.4 ± 14.7 energy applications per patients. There were no acute procedural complications.

Conclusions: Percutaneous, transcatheter microwave ablation of CTI dependent atrial flutter was demonstrated to be safe and effective in this preliminary feasibility study.
Clinical Implications of Reconnection Between the Left Atrium and Isolated Pulmonary Veins Provoked by Adenosine Triphosphate after Extensive Encircling Pulmonary Vein Isolation
Authors: HACHIYA HITOSHI , HIRAO KENZO , TAKAHASHI ATSUSHI , NAGATA YASUTOSHI , SUZUKI KENJI , MAEDA SHINGO , SASAKI TAKESHI , KAWABATA MIHOKO , ISOBE MITSUAKI , IESAKA YOSHITO
Published: February 2007

Introduction: Dormant pulmonary vein (PV) conduction can be provoked by adenosine triphosphate (ATP) after extensive encircling pulmonary vein isolation (EEPVI). However, the clinical implication of reconnection between the left atrium (LA) and isolated PVs provoked by ATP (ATP‐reconnection) remains unknown.

Methods and Results: We studied the clinical consequences of ATP‐reconnection during intravenous isoproterenol infusion (ISP‐infusion). EEPVI severs conduction between the LA and ipsilateral PVs at their junction. Radiofrequency energy is applied at a distance from the PV ostia guided by double Lasso catheters placed within the ipsilateral superior and inferior PVs. This study comprised 82 patients (67 men, 56 ± 9 years old) with atrial fibrillation (AF) who underwent injection of ATP during ISP infusion after successful EEPVI (ATP(+) group). We compared clinical characteristics of 170 patients who underwent earlier EEPVI prior to our use of ATP injection after successful EEPVI (ATP(N/D) group) with those of ATP(+) group patients who underwent one session of EEPVI. ATP‐reconnection occurred in 34 (41%) of 82 ATP(+) group patients. Additional radiofrequency applications were performed to eliminate ATP‐reconnection in all ipsilateral PVs. Continuous ATP‐reconnection of more than 20 seconds duration occurred in six (7.3%) of 82 patients. A total of 102 (60%) of 170 patients in the ATP(N/D) group had no recurrence of AF, whereas 60 (73%) of 82 ATP(+) group patients who underwent only one EEPVI session have had no recurrence of AF in a 6.1 ± 3.3‐month follow‐up period (P = 0.04).

Conclusion: Radiofrequency application for provoked ATP‐reconnection may reduce clinical AF recurrence.
Focal Atrial Tachycardias Arising from the Right Atrial Appendage: Electrocardiographic and Electrophysiologic Characteristics and Radiofrequency Ablation
Authors: ROBERTS‐THOMSON KURT C. , KISTLER PETER M. , HAQQANI HARIS M. , McGAVIGAN ANDREW D. , HILLOCK RICHARD J. , STEVENSON IRENE H. , MORTON JOSEPH B. , VOHRA JITENDRA K. , SPARKS PAUL B. , KALMAN JONATHAN M.
Published: February 2007

Objective: To characterize the electrocardiographic and electrophysiological features and frequency of focal atrial tachycardia (AT) originating from the right atrial appendage (RAA).

Background: The RAA has been described as a site of origin of AT, but detailed characterization of these tachycardias is limited.

Methods: Ten patients (3.8%) of 261 undergoing radiofrequency ablation (RFA) for focal AT are reported. Endocardial activation maps (EAM) were recorded from catheters at the CS (10 pole), tricuspid annulus (20 pole Halo catheter), and His positions. P waves were classified as negative, positive, isoelectric, or biphasic.

Results: The mean age was 39 ± 20 years, nine males, with symptoms for 4.1 ± 5.1 years. Tachycardia was incessant in seven patients, spontaneous in one patient, and induced by programmed extrastimuli in two patients. These foci had a characteristic P wave morphology. The P wave was negative in lead V1 in all patients, becoming progressively positive across the precordial leads. The P waves in the inferior leads were low amplitude positive in the majority of patients. Earliest EAM activity occurred on the Halo catheter in all patients. Mean activation time at the successful RFA site =−38 ± 15 msec. Irrigated catheters were used in six patients, due to difficulty achieving adequate power. RFA was acutely successful in all patients. Long‐term success was achieved in all patients over a mean follow up of 8 ± 7 months.

Conclusions: The RAA is an uncommon site of origin for focal AT (3.8%). It can be suspected as a potential anatomic site of AT origin from the characteristic P wave and activation timing. Irrigated ablation catheters are often required for successful ablation. Long‐term success was achieved with focal ablation in all patients.
Improvement of Cystic Fibrosis During Treatment With Isotretinoin
Authors: Buckley Jennifer L. , Chastain Mark A. , Rietschel Robert L.
Published: February 2007

A 15‐year‐old boy with a history significant for multiple respiratory infections since birth presented for evaluation of acne vulgaris. He was initially prescribed doxycycline, topical tretinoin, and topical clindamycin solution, with the later addition of a benzoyl peroxide preparation to his regimen. The patient returned 6 months later after having been diagnosed with CF (cystic fibrosis) by sweat testing and genetic testing. His skin condition had not responded adequately to prior therapy, so all acne medications were discontinued. The 84‐kg patient was started on 80 mg (0.95 mg/kg/d) of isotretinoin (13‐cisretinoic acid) daily. The patient's dose was decreased to 40 mg/d 2 weeks later following an episode of blood in his stool and epistaxis. At the 1‐ and 2‐month follow‐up visits, the patient reported improvement in his acne and mentioned that his lung secretions seemed reduced. His acne cleared after 4 months of therapy, so the isotretinoin was discontinued. The patient and his mother noted that no respiratory infections had occurred during the course of therapy. The patient's acne relapsed nearly 2 years later, so isotretinoin was restarted at 60 mg/d. During the next 7 months while on the drug, he experienced no further episodes of epistaxis or bloody stools and his acne had resolved by the end of therapy. The patient and his mother again reported fewer bronchopulmonary secretions and no infections requiring antibiotics during treatment with isotretinoin. This was unusual because he had experienced numerous respiratory infections requiring antibiotics during the prior 2 years. Since discontinuing the drug, the patient has had intermittent pulmonary infections and exacerbations in the symptomatology of his CF.
The Blue Peel: How to Do It Less Expensively and Faster
Authors: Wolf Ronni , Marcos Batsheva , Orion Edith , Matz Hagit
Published: February 2007

One well accepted and popular method worldwide for trichloroacetic acid peels is the Obagi Blue Peel technique (Obagi Medical Products, Long Beach, CA). The peel solution is prepared by mixing a fixed volume of 30% trichloroacetic acid with the commercially available Blue Peel base. The authors suggest modifications for performing the peeling faster and less expensively: 1) preparing a larger volume of peel solution from each tube of Blue Peel base; 2) using higher concentrations of peel solution to reduce the number of coats necessary for reaching the desired depth of peel; and 3) storing the solution, as there is no need to adhere to the manufacturer's instructions to prepare the solution immediately before conducting the peel procedure to ensure homogeneity of the solution. The prepared solution can be stored at least 1 year.
Tailoring Dielectric Properties of Multilayer Composites Using Spark Plasma Sintering
Authors: Elissalde Catherine , Maglione Mario , Estournès Claude
Published: February 2007

A straightforward and simple way to produce well‐densified ferroelectric ceramic composites with a full control of both architecture and properties using spark plasma sintering (SPS) is proposed. SPS main outcome is indeed to obtain high densification at relatively low temperatures and short treatment times thus limiting interdiffusion in multimaterials. Ferroelectric/dielectric (BST64/MgO/BST64) multilayer ceramic densified at 97% was obtained, with unmodified Curie temperature, a stack dielectric constant reaching 600, and dielectric losses dropping down to 0.5%, at room‐temperature. This result ascertains SPS as a relevant tool for the design of functional materials with tailored properties.
Antemortem Records of Forensic Significance Among Edentulous Individuals
Authors: Richmond Raymond , Pretty Iain A.
Published: February 2007

ABSTRACT: The identification of edentulous individuals is problematic due to poor provision of labelled dental prostheses. Dental records may still provide useful information for odontologists in the comparative identification process. The purpose of this study was to determine the level of forensically significant information contained within the dental records of a population of denture wearers attending the University of Manchester School of Dentistry. Two hundred and two dental records were examined and a proforma completed. The mean age of the patients was 72 years. Medical history were absent in 4% of all records and only 67.8% of the written records were rated as good. Thirty‐two percent of the records contained one or more panoramic radiographs but 30% of these were over 3 years old rendering their usefulness in identification procedures questionable. In total only 18% of the examined records contained antemortem information that would enable identification. These data suggest that the process of denture marking is an essential in order to ensure that the identification of this population can be undertaken expediently by dental means.
Obesity‐Related Cardiovascular Risk in Children and the Role of Lifestyle Changes
Authors: Balagopal Prabhakaran
Published: February 2007

Overweight and obesity in children present significant public health concerns because of the link with numerous chronic health conditions, especially type 2 diabetes and cardiovascular disease. Perhaps obesity is only the visible pointer of other underlying risk factors for these disease conditions in childhood. Although an imbalance between energy consumed and expended appears to be the simplistic underlying problem for the increased prevalence of obesity, it is a complex condition, with various contributing factors, and may be considered the metabolic factory for various risk factors for cardiovascular disease, both modifiable and nonmodifiable. It has also been recognized that the risk factors emerge quite early in the clinical course of obesity. Physical activity‐based lifestyle change appears to be the most variable component of energy expenditure and therefore has been the obvious choice and the target of behavioral interventions to modify body weight in children. This review focuses on the obesity‐related nontraditional risk factors for cardiovascular disease in children and the role of lifestyle changes in modulating these risk factors.
On the ocular refractive components: the Reykjavik Eye Study
Authors: Olsen Thomas , Arnarsson Arsaell , Sasaki Hiroshi , Sasaki Kazuyuki , Jonasson Fridbert
Published: February 2007

Purpose:  To study the correlation between ocular refraction and the refractive components (corneal power, lens power and axial length) in a population‐based sample of normal subjects.

Methods:  We analysed the refractive and biometric findings for 723 right eyes (325 males and 398 females) comprising a population‐based random sample of citizens 55 years and older participating in the Reykjavik Eye Study. Measurements of refraction, corneal curvature (by keratometry), anterior chamber depth, lens thickness and axial length (all by ultrasound biometry) were used to calculate crystalline lens power. The correlation and regression between refraction and ocular refractive components (corneal power, anterior chamber depth, lens power and axial length) were studied by distributional statistical methods.

Results:  Refraction (spherical equivalent) showed a significant negative correlation with axial length (r = –0.59, P < 0.0001), lens power (r = –0.26, P < 0.0001) and corneal power (r = –0.16, P < 0.0001). There were significant negative correlations between axial length and corneal power (r = –0.44, P < 0.0001) and between axial length and lens power (r = –0.44, P < 0.0001). Based on multiple linear regression analysis, refraction could be correlated with corneal power, lens power and axial length in combination with a correlation coefficient of 0.98 (P < 0.0001).

Conclusion:  This study confirms that ocular refraction is statistically significantly correlated with not only axial length but also lens power and (to a lesser extent) corneal power. The variation and correlations of crystalline lens power were considerable – possibly indicating this component's modulatory effect on ocular refraction during growth. We conclude the refractive error of the eye to be a multifactorial condition involving a complex interplay between the cornea, the lens and the length of the eye.
Oxymetazoline modulates proinflammatory cytokines and the T‐cell stimulatory capacity of dendritic cells
Authors: Tuettenberg Andrea , Koelsch Stephan , Knop Jürgen , Jonuleit Helmut
Published: February 2007

Abstract:  The nasal decongestant oxymetazoline (OMZ) is frequently used in the topical treatment of rhinitis/sinusitis. As proinflammatory cytokines play a critical role in the development and maintenance of local inflammation, the aim of this study was to investigate the influence of OMZ on immune cells in order to diminish the mucosal infiltration of the nose. Peripheral blood mononuclear cells (PBMC) from buffy coats of healthy volunteers were isolated and stimulated in the presence or absence of OMZ. In addition, monocyte‐derived dendritic cells (DC) were generated and different concentrations of OMZ were added. DC phenotype and their T‐cell stimulatory properties were analysed. The vasoactive substance OMZ showed a concentration dependent inhibitory effect on T‐cell activation as well as a dominant effect on T‐cell stimulatory properties of DC. Low concentrations of OMZ inhibited the proliferation of polyclonally activated T cells. In addition, secretion of proinflammatory mediators such as the cytokines interleukin‐1β (IL‐1β), tumor necrosis factor‐α (TNF α), IL‐6 and IL‐8 were inhibited in the presence of physiological doses of OMZ. Interestingly, the addition of IL‐6 to DC‐T‐cell co‐culture was able to completely restore T‐cell proliferation. In conclusion, these findings indicate that the anti‐inflammatory properties of OMZ are partially mediated by the inhibition of proinflammatory cytokines as well as reduced T‐cell stimulatory capacity of DC resulting in a repressed stimulation of T cells. Therefore, the therapeutic benefit of OMZ can be explained in part by its immunomodulating effects in the topical treatment of nasal inflammation.
The oral health and treatment needs of community‐dwelling older people in a rural town in Western Australia
Authors: Kruger Estie , Tennant Marc , Smith Kirrilee , Peachey Jacinta
Published: February 2007

Objectives: The aim of this study was to assess, in a sample of older rural community‐dwelling Australians, their: oral health status, dental treatment needs, perceived barriers to access dental services and the prevalence and severity of dental anxiety.

Methods: A cross‐sectional study of elderly rural Australians.

Results: Eighty participants (mean age of 71.7 years) had a mean number of 0.69 (SD 1.6) decayed teeth, 15.72 (SD 13.3) missing teeth and 3.9 (SD 5.4) filled teeth. Forty‐one per cent were edentulous. Xerostomia was reported by 53% of the edentulous and 43% of the dentate. The average Corah Dental Anxiety Scale score was 8.72 (SD 3.8). Prevalence of dental anxiety was 15.6%. Two‐thirds needed dental treatment.

Conclusions: Caries experience was lower than that reported in other studies. Reported barriers to use of dental services were long waiting times, lack of perceived dental need and costs.
Influence of age on exophthalmos and thyrotrophin receptor antibodies in 123 untreated patients with Graves’ disease and 560 normal control subjects
Authors: Takasu Nobuyuki , Nakamatsu Takashi , Nakachi Ken
Published: February 2007

Objective: The influence of age on exophthalmos and thyrotrophin receptor antibodies (TRAb) was studied in untreated patients with Graves’ disease (GD). Exophthalmos measurement is useful for GD diagnosis in elderly Japanese patients.

Subjects and methods: Protrusions of the eyes (exophthalmic values: EV) and TRAb were studied in 123 untreated patients with GD and 560 controls. Patients with GD and controls were divided into seven age groups. The receiver operating characteristic (ROC) analysis was done to evaluate the clinical usefulness of EV for GD diagnosis.

Findings: The differences of EV between patients with GD and controls were significant in those aged 60 years and over (≥ 60 years). ROC analysis showed that the sensitivity and specificity of EV were high in elderly groups (≥ 60 years), but not in the others (< 60 years).

Conclusion: Exophthalmic values have clinical usefulness for GD diagnosis in elderly Japanese. An EV has a diagnostic value for GD in elderly patients (≥ 60 years).
A survey of H2 gene sequences, including new wild‐derived genes
Authors: Mitchison N. A. , Mayer W.
Published: February 2007

A comprehensive collection of mouse major histocompatibility complex (MHC) promoter and exon 2 sequences is here presented and analysed. It covers the three best known class II genes and one class I gene, and includes new wild mouse sequences from the ‘w’ back‐cross strains and from the Jackson collection. All sequences are in GenBank, and the new exon sequences largely confirm previous typing by serology and immune function. As in human leucocyte antigen (HLA), the overall nucleotide diversity is higher in the class II genes, in keeping with their more diverse function. Diversity along the promoters is highest in the region of known transcription factor binding, most notably in and around the CRE and rCAAT sequences. This distribution parallels that of maximum single nucleotide polymorphism impact previously obtained with reporter constructs. Taking into account the low nucleotide diversity of the CIITA promoter, we conclude that MHC promoters are likely to have diversified through co‐evolution with their exons, while themselves also directly subject to natural selection. The H2Ebp alleles form a distinct group, associated with their lack of the recombination hot spot located between exon 2 and exon 3. The collection is expected to prove useful in guiding functional and evolutionary studies.
Attachment Theory and Reactive Attachment Disorder: Theoretical Perspectives and Treatment Implications
Authors: Hardy Lyons T.
Published: February 2007

TOPIC:  Attachment theory and reactive attachment disorder (RAD).

PURPOSE:  To highlight current perspectives on attachment theory, RAD, and treatment implications using a case study of an 8‐year‐old patient with RAD.

SOURCES:  Selected multidisciplinary literature related to attachment theory and RAD.

CONCLUSIONS:  The literature provides a body of work that substantiates the importance of early attachment relationships to human development and highlights gaps in our knowledge related to treatment of children with RAD. The quality of early attachment relationships is correlated with future personality and brain development. Attachment disturbances are associated with psychopathology in childhood and adulthood. Although evidence for the effective treatment of children with attachment disorders is minimal and inconclusive, the two major perspectives, developmental psychology and neuropsychoanalysis, offer guidelines for practice.
Metal contact formation by microdeposition of nondestructive particles from focused ion beam sputtering
Authors: Shiue J. , Kuo P. C. , Wang Y. L.
Published: February 2007

A microdeposition technique based on focused ion beam (FIB) sputtering has been developed to overcome the problems of ion radiation damage and high impurity concentration found in metal contacts deposited by FIB-induced deposition from organometallic gas. This damage-free technique is most useful for making metal electrodes onto nonplanar samples such as micron-sized single crystals and nanowires. To demonstrate the capability, four Au wires were connected to an ∼200μm NbSe2 single crystal, and its resistivity versus temperature characteristics were measured. This FIB sputtering microdeposition method with micron-scale spatial resolution can be employed for the deposition of any material.
Low-stress silicon carbonitride for the machining of high-frequency nanomechanical resonators
Authors: Fischer L. M. , Wilding N. , Gel M. , Evoy S.
Published: February 2007

The synthesis of silicon carbonitride by low-temperature plasma-enhanced chemical vapor deposition and the machining of nanomechanical resonators in this material are reported. Films with thickness of 1μm, 200nm, and 50nm were deposited using ammonia, nitrogen, and diethylsilane as precursors. X-ray photoelectron spectroscopy indicated that usage of higher NH3:DES gas flow ratios results in higher nitrogen and low carbon contents in the deposited films. In addition, annealing of the material enabled the full tunability of its residual stress from the compressive to the tensile range. Infrared spectroscopy indicated that desorption of incorporated hydrogen was responsible for those changes. Assaying of resonant cantilevers fabricated from 200-nm-thick films yielded root-modulus-over-density values as high as √(E∕ρ)=8.35×103m∕s, comparable to those of silicon. Doubly clamped beams were also fabricated from 50-nm-thick films of low (σ=80MPa) and high (σ=220MPa) tensile stresses. Beam resonators fabricated in the lower stress material showed resonance qualities ranging between 3000 and 5000, and resonant frequencies between f=6.1MHz and f=16MHz. Beam resonators machined in the higher stress material experienced quality factors between 8000 and 23 000 and frequencies between f=7.6 and 24MHz. These values correspond to fQ products as high as of 1.5×1011s−1, exceeding the performance of previously reported silicon resonators.
Ballistic recovery in III-V nanowire transistors
Authors: Gilbert M. J. , Banerjee S. K.
Published: February 2007

In recent years, a great deal of attention has been focused on the development of quantum wire transistors as a means of extending Moore’s law. Here the authors present results of fully three-dimensional, self-consistent quantum mechanical device simulations of InAs trigate nanowire transistor. The effects of inelastic scattering have been included as real-space self-energy terms. They find that the position of dopant atoms in these devices can lead to a reduction in the amount of scattering the carriers experience. They find that the combination of deeply buried dopant atoms and the high energy localization of polar optical phonon processes allow devices to recover their ballistic behavior even in the presence of strong inelastic phonon processes.
Local line edge roughness in microphotonic devices: An electron-beam lithography study
Authors: Ma Yuansheng , Cheng Yang-chun , Cerrina Franco , Barwicz T. , Smith H. I.
Published: February 2007

Microphotonic resonators are very sensitive to sidewall roughness. Several structures with sub-100-nm gap between bus and ring have been patterned on silicon-on-insulator wafer with 50keV electron-beam lithography at different doses. The authors’ direct Monte Carlo (DMC) model has been used to model the electron scattering and energy deposition to predict proximity effects and image modulation. By comparing the point spread function from DMC with independent experimental results, the DMC model has been validated. Experimentally, the line edge roughness (LER) study has been carried out to include both the first order (standard deviation) and the second order of statistical analysis (correlation length). The authors found that the LER is not uniform and varies with the position along the pattern—this nonlocal LER may have profound implications for the performance of the devices. The highest local LER is obtained at the position when the bus is closest to the ring. This phenomenon will be exacerbated when the gap size becomes smaller and will affect coupling efficiency of the waveguides.
Influence of oxygen diffusion on residual stress for tantalum thin films
Authors: Cheng M. H. , Cheng T. C. , Huang W. J. , Chang M. N. , Chung M. K.
Published: February 2007

The influence of oxygen diffusion on the residual stress of 500Å thick tantalum thin films sputtered on Si substrate after annealing temperature from 200to400°C is examined in this article. The intensity of diffraction peaks for tetragonal β-Ta phase decreases when annealing temperatures increase by utilizing glancing incident angle x-ray diffraction measurements, and x-ray photoelectron spectroscopy was performed to understand the Ta2O5 oxidation layer on the surface of Ta films after the annealing processes. Furthermore, simulated x-ray reflectivity (XRR) results show that the thicker Ta2O5 oxidation layer is formed when the annealing temperature increases. The compressive stress is nearly proportional to the thickness of the Ta2O5 oxidation layer after the annealing process because of the incorporation of the oxygen into interstitial sites of β-Ta unit cell, which leads to the 5.4Å3 volume expansion of the β-Ta unit cell. Besides, Auger electron spectroscopy was also used to analyze the depth profile of oxygen diffusion which has consistent tendency with XRR results. The above results indicate that oxidation of Ta films with annealing processes will increase the compressive stress in textured β-Ta thin films.
Novel Samsung advanced resist for thermal flow process material for nano-processing
Authors: Choi Sang-Jun
Published: February 2007

A resist flow process using a cross-linkable additive called the Samsung advanced resist for thermal flow process (SMART) was studied. SMART consists of conventional polyhydroxystyrene-based polymers and additives inducing thermal cross-linking reactions with the base polymers. With the SMART resist, 240nm contact holes were defined by KrF lithography system, and then following a one-step thermal flow process, resulted in contact holes down to 80nm with a vertical sidewall profile. At 90nm resolution, the critical dimension variation on a 200mm wafer was less than 10nm. It also showed good etch selectivity to silicon oxide due to the cross-linking reaction of the additive. The main advantage of the SMART system is a one-step process having a linear dependency of flow rate on baking temperature. The amount of resist flow can be controlled within the range of 100–150nm without any significant pattern deformation. The thermal flow process using the SMART is a promising candidate for the fabrication of nanodevices.
Vapor phase deposition of oligo(phenylene ethynylene) molecules for use in molecular electronic devices
Authors: Gergel-Hackett Nadine , Cabral Michael J. , Pernell Timothy L. , Harriott Lloyd R. , Bean John C. , Chen Bo , Lu Meng , Tour James M.
Published: February 2007

The field of molecular electronics is often limited by nonreproducible electrical device characteristics and low yields of working devices. These limits may result from inconsistencies in the quality and structure of the monolayers of molecules in the devices. In response, the authors have developed an ultrahigh vacuum vapor phase deposition method that reproducibly assembles monolayers of oligo(phenylene ethynylene) molecules (the chemical backbone of many of the molecules used in molecular electronics). To improve the structure and purity of the monolayer, the vapor phase assembly is performed in an ultrahigh vacuum environment using a low temperature organic thermal cell. Because vapor phase assembly does not require the use of solvents, a potential source of contamination is eliminated. The absence of solvents also permits the fabrication of complex device architectures that require photoresist patterning prior to the molecular assembly. Characterization via ellipsometry, x-ray photoelectron spectroscopy, and scanning tunneling microscopy shows that the monolayers are dense, chemisorbed, ordered, and chemically pure.
Probabilistic analysis of drilled shaft service limit state using the "t–z" method
Authors: Misra Anil , Roberts Lance A
Published: February 2007

The utility of the load and resistance factor design (LRFD) approach is being increasingly recognized for the design of drilled shafts. The current LRFD methodologies of drilled shaft design would be more efficient if reliability based design approaches were used for service limit state design. In this paper, the "t–z" methodology is utilized to develop probabilistic approaches for axial service limit state analysis of drilled shafts. Two different models of the soil–shaft interaction are implemented for load displacement calculations: (1) an ideal elastoplastic model, and (2) a hyperbolic model. For both of these soil–shaft interactions, Monte Carlo simulation is used to obtain a large set of load–displacement curves assuming lognormal distributions for the shaft–soil interface properties. The load–displacement curves are analyzed to develop two alternate methods for determining the probability of drilled shaft failure at the service limit state. As a result, cumulative distribution histograms are developed for drilled shaft load capacities at allowable head displacements. These results may be utilized to obtain resistance factors that can be applied to LRFD based service limit state design.Key words: drilled shaft, serviceability, failure probability, load displacement relation, "t–z" method.
PHANTOM FIELD FROM CONFORMAL INVARIANCE
Authors: HASSAÏNE MOKHTAR
Published: February 2007

We establish a correspondence between a conformally invariant complex scalar field action (with a conformal self-interaction potential) and the action of a phantom scalar field minimally coupled to gravity (with a cosmological constant). In this correspondence, the module of the complex scalar field is used to relate conformally the metrics of both systems while its phase is identified with the phantom scalar field. At the level of the equations, the correspondence allows to map solution of the conformally nonlinear Klein–Gordon equation with vanishing energy–momentum tensor to solution of a phantom scalar field minimally coupled to gravity with cosmological constant satisfying a massless Klein–Gordon equation. The converse is also valid with the advantage that it offers more possibilities owing to the freedom of rewriting a metric as the conformal transformation of another metric. In three dimensions, the coupling of this matter action to conformal gravity is put in equivalence with topologically massive gravity with a cosmological constant and with a phantom source. Finally, we provide some examples of this correspondence.
ABSORPTION, EMISSION AND NONLINEAR SPECTROSCOPIC CHARACTERIZATION OF REACTIVE DYE
Authors: GUO SHENG-LI , GUO ZHUN , SUSDORF T. , CAO TIAN-DE
Published: February 2007

An optical spectroscopic characterization is carried out on a reactive dye (reactive orange 1). This dye is widely applied in textile coloration. It is a potential candidate for photonics applications. Its absorption cross-section spectra are measured. A fluorescence spectroscopic characterization is undertaken by measuring the fluorescence quantum distributions and fluorescence quantum yields. The saturable absorption is studied by nonlinear transmission measurements with intense picosecond laser pulses (second harmonic pulses of a mode-locked Nd :glass laser). The nonlinear optical absorption and refraction coefficients are measured by using the top-hat Z-scan technique at a wavelength of 532 nm with 35 ps duration pulses. Reactive orange 1 has the two-photon absorption coefficient of 1.20 cm/GW and the nonlinear refraction coefficient of -7.33 × 10-6 cm2/GW, respectively. In reactive orange 1, there occurs fast ground-state recovery by internal conversion likely via conical intersections. Low excited-state absorption and fast ground-state absorption recovery make it an ideal candidate for passive mode-locking of picosecond and femtosecond lasers as well as for fast nonlinear optical gating.
ANALYSIS OF SPIDER INTERFEROGRAMS WITH THE FRACTIONAL-ORDER FOURIER SERIES EXPANSION
Authors: BRUNEL MARC , COETMELLEC SEBASTIEN
Published: February 2007

We propose the use of fractional-order Fourier series expansion for the characterization of ultrashort pulses. The analysis and reconstruction of simulated SPIDER interferograms is demonstrated with this decomposition process. We consider the case of ultrashort pulses (about 100 fs) that have been subject to second- and third-order dispersion. Our technique allows the simultaneous determination of the quadratic and cubic spectral phase coefficients of the pulses. The technique can be further used to analyze, filter or reconstruct noisy SPIDER interferograms.
Role of phosphatidylinositol-3 kinase-γ in the actions of glucagon-like peptide-2 on the murine small intestine
Authors: Anini Younes , Izzo Angelo , Oudit Gavin Y. , Backx Peter H. , Brubaker Patricia L.
Published: February 2007

Glucagon-like peptide-2 (GLP-2) enhances intestinal growth and function through a cAMP-linked G protein-coupled receptor (GPCR) expressed in the mucosal layer and enteric nervous system. Because the type 1B γ-isoform of phosphatidylinositol 3-kinase (PI3-K) is activated by GPCRs, we determined whether this enzyme plays a role in the intestinal actions of GLP-2 by using PI3-Kγ knockout (KO) mice. Wild-type (WT), heterozygous, and KO mice were treated with vehicle or 1 μg Gly2-GLP-2 (a long-acting analog) twice daily for 10 days and analyzed for changes in intestinal growth, motility, and cAMP production. Basal small intestinal wet weight was increased in KO mice in association with enhanced crypt-villus height and crypt cell proliferation ( P < 0.05–0.01). However, the GLP-2-induced changes in these parameters were not different between KO and WT animals. GLP-2 treatment also enhanced the number of mucous cells in the intestinal epithelium, but this effect was lost in the PI3-Kγ KO mice. Both basal and GLP-2-induced suppression of intestinal transit were normal in KO mice. In contrast, the ability of GLP-2 to stimulate cAMP levels in isolated muscle strips was abrogated by loss of PI3-Kγ, despite the expression of GLP-2 receptor mRNA transcripts in this tissue. Together, the results of this study demonstrate a role for PI3-Kγ in basal but not GLP-2-induced small intestinal mucosal growth. However, PI3-Kγ is important for the enhancement of mucous cell number by GLP-2 and in the ability of the GLP-2 receptor to couple to cAMP in the enteric nervous system.
Drosophila dMRP4regulates responsiveness to O2deprivation and development under hypoxia
Authors: Huang He , Haddad Gabriel G.
Published: February 2007

For most vertebrates, oxygen is a prerequisite for survival. Although we have previously shown that Drosophila melanogaster is hypoxia tolerant, how this species senses O2deprivation and how it survives oxygen-limiting conditions are as yet poorly understood. We began to address this question by testing for anoxic responsiveness in Drosophila adult flies following overexpression of existing EP lines. In this screen, we identified Drosophila CG14709 gene as a homolog of the human multidrug resistance protein 4 (MRP4/ABCC4) that is tightly regulated to oxygen. Ubiquitous expression of dMRP4 in adult flies resulted in increased sensitivity to anoxia as they had longer recovery time from anoxic stupor. When exposed to 4% oxygen chronically (throughout its lifespan), constitutive expression of dMRP4 in larvae caused larval lethality due to growth arrest. Mutations of dMRP4 led to a hypersensitive response to acute anoxia in adult flies but had less impact on larval survival under chronic hypoxia compared with dMRP4 overexpression. Selective expression of this gene in neurons, but not in glia or muscles, mirrored the same phenotype as the ubiquitous one. Thus, our data suggest novel roles for MRP in vivo: 1) dMRP4 regulates the sensitivity to acute or chronic O2deprivation, and 2) dMRP expression in neurons is sufficient to induce the sensitivity to O2in the whole organism.
Identification of reference genes for quantitative real-time PCR in the bovine mammary gland during the lactation cycle
Authors: Bionaz Massimo , Loor Juan J.
Published: February 2007

Achieving greater understanding of the genomic influence on milk synthesis in dairy cows represents a daunting challenge. Bovine-specific microarrays have allowed for high-throughput gene expression analysis of the mammary transcriptome. However, real-time PCR (qPCR) still represents the method of choice for accurate expression profiling of small numbers of genes and verification of key microarray relationships. This method is extremely sensitive but requires data normalization to account for analytical errors. Ideally, expression of genes used as internal controls should not be affected by specific treatments or physiological state. Mammary biopsies were collected from five cows each at −15, 1, 15, 30, 60, 120, and 240 days relative to parturition for gene expression profiling. We evaluated expression of nine genes ( RPS9, ACTB, GAPD, GTP, ITGB4BP, MRPL39, RPS23, RPS15, and UXT) that could serve as internal controls in mammary tissue using qPCR. Due to gradual increases in mammary RNA concentration (μg/mg tissue) over lactation, all genes investigated experienced a dilution effect. We used pairwise comparison of expression ratios to analyze the reliability of these genes as internal controls. UXT, RPS9, and RPS15 had the most stable expression ratios across cow and time. We also assessed co-regulation among genes through network analysis. Network analysis suggested co-regulation among most of the genes examined, with MYC playing a central role. Pairwise comparison was suitable for finding appropriate internal controls in mammary gland tissue. Results showed that the geometrical average of UXT, RPS9, and RPS15 expression could be used as internal control for longitudinal mammary gene expression profiling.
Numerical Simulation of the Transitional and Unsteady Flow through a Low Pressure Turbine
Authors: Skoda Romuald , Schilling Rudolf , Schobeiri Meinhard T.
Published: February 2007

A simulation strategy is developed for the computation of the time-accurate flow through low pressure turbines with periodically impinging wakes generated by moving cylinder rods. For the simulations, different time steps and turbulent inflow conditions and their impact on the laminar separation on the suction side are considered. A realizable cubic low-Reynolds numberk-ɛturbulence model and a linear V2F model are utilized to capture transitional effects, in particular the laminar separation bubble at the suction side. For comparison with experimental data, published in a companion paper, pressure distribution and boundary layer profiles of the mean and fluctuation RMS velocity are considered. While the periodically disturbed flow is predicted with a reasonable accuracy by each model, for the undisturbed flow, an additional realizability condition based on a turbulent time scale bound is incorporated into the cubic model in order to capture the reattachment of the flow.
Effects of Various Forms of Calcium Added to Chewing Gum on Initial Enamel Carious Lesions in situ
Authors: Schirrmeister J.F. , Seger R.K. , Altenburger M.J. , Lussi A. , Hellwig E.
Published: February 2007

The purpose of this randomized, cross-over in situ study was to determine the effects of 4 chewing gums on artificial caries-like subsurface lesions. Two chewing gums (1 with zinc citrate and 1 without) contained dicalcium phosphate (3.9%), calcium gluconate (1.8%) and calcium lactate (0.45%), 1 chewing gum contained casein phosphopeptide-amorphous calcium phosphate nanocomplexes (0.7%), and another one contained no calcium. Fifteen subjects without current caries activity (7 male, 8 female; mean age: 27.5 ± 2.5 years) wore removable buccal appliances in the lower jaw with 4 bovine enamel slabs with subsurface lesions. The appliances were inserted immediately before gum chewing for 20 min and then retained for an additional 20 min. This was performed 4 times per day. Every subject chewed 4 different chewing gums over 4 periods of 14 days each. During a fifth period (control) the subjects only wore the appliances without chewing gum. At completion of each period the enamel slabs were embedded, sectioned and subjected to transversal microradiography. With regard to change of mineral loss and of lesion depth no significant differences could be found between chewing gums containing calcium and calcium-free chewing gums. Moreover, the chewing gum groups and the control group did not differ significantly if adjustments were made for baseline values (p > 0.05; ANCOVA). Under the conditions of the present study it may be concluded that the use of chewing gum offers no additional remineralizing benefit to buccal tooth surfaces, even if the chewing gum contains calcium compounds.
Accuracy and Reproducibility of Conventional Radiographic Assessment and Subtraction Radiography in Detecting Demineralization in Occlusal Surfaces
Authors: Ricketts D.N.J. , Ekstrand K.R. , Martignon S. , Ellwood R. , Alatsaris M. , Nugent Z.
Published: February 2007

Subjective interpretation of paired digital radiographic images viewed side by side to assess occlusal lesion progression, arrest or remineralization is difficult. The aim of this study was to compare the accuracy and reproducibility of a digital subtraction radiography technique and visual assessment of paired digital images in detecting changes in mineral content within occlusal cavities. Forty molar teeth with occlusal cavities were placed in arches and baseline digital radiographs taken. Nineteen teeth were randomly selected and had acid placed in the cavities and digital images taken after 3, 6, 12, 18 and 24 h of acid exposure. Paired baseline images and those taken at the various time intervals were examined side by side and assessed for demineralization by five examiners. Subtraction images prepared from the paired images were assessed in the same way. One fifth of the images were re-examined to determine intra-examiner reproducibility. After 12 h or longer the diagnostic accuracy (mean area under the ROC curve = 0.92–0.98 for subtraction radiography), intra-examiner and inter-examiner reproducibility for detection of demineralization from the subtraction images was significantly better than viewing the paired images side by side (p < 0.01). The subtraction radiography system used was found to be more accurate and reproducible than visual assessment of paired digital images. As such the technique shows promise for monitoring occlusal lesion progression in clinical studies.
Demineralisation of Permeable Hydroxyapatite with Alternating Water and Acidic Buffer: Scanning Microradiographic Study of Effect of Switching Period
Authors: Bollet-Quivogne F.R.G. , Anderson P. , Dowker S.E.P. , Elliott J.C.
Published: February 2007

Permeable hydroxyapatite (HAP) blocks were exposed for equal times alternately to pH 4.0 buffer and water for 237 h. Rates of HAP loss with time (determined from changes in X-ray attenuation) were measured as a function of switching period τ (the time for a complete cycle) from 0.5 to 6 h and with a continuous buffer flow. The mean rate of HAP loss decreased markedly as τ increased, and for large τ was about half the rate for continuous buffer flow. We propose that demineralising conditions through the depth of the HAP are influenced by the extent of retention of buffer within its pores which will depend on τ. A mathematical model with parameters R₀ and Δt was developed, where R₀ is the rate of demineralisation for continuous flow, and Δt a time added to each τ/2 buffer exposure to account for its retention in the HAP pores. Experimental data fitted the model with Δt ∼8 to ∼10 min and with R₀ close to the rate observed for continuous buffer flow. The model predicts that the rate decreases and approaches R₀/2 as τ → ∞, as was found experimentally to be the case. This type of study could potentially give information about subsurface porosity and transport processes during acidic dissolution of permeable solids, for example in dental caries and dental erosion.