bluuebunny/crossref_metadata_2025 huggingface dataset:
Superoxide (·O2−) Production in CA1 Neurons of Rat Hippocampal Slices Exposed to Graded Levels of Oxygen
Authors: D'Agostino Dominic P. , Putnam Robert W. , Dean Jay B.
Published: June 2007

Neuronal signaling, plasticity, and pathologies in CA1 hippocampal neurons are all intimately related to the redox environment and, thus tissue oxygenation. This study tests the hypothesis that hyperoxic superfusate (95% O2) causes a time-dependent increase in superoxide anion (·O2−) production in CA1 neurons in slices, which will decrease as oxygen concentration is decreased. Hippocampal slices (400 μm) from weaned rats were incubated with the fluorescent probe dihydroethidium (DHE), which detects intracellular ·O2−production. Slices were loaded for 30 min using 10 μM DHE and maintained using one-sided superfusion or continuously loaded using 2.5 μM DHE and maintained using two-sided superfusion (36°C). Continuous loading of DHE and two-sided superfusion gave the highest temporal resolution measurements of ·O2−production, which was estimated by the increase in fluorescence intensity units (FIUs) per minute (FIU/min ± SE) over 4 h. Superoxide production (2.5 μM DHE, 2-sided superfusion) was greatest in 95% O2(6.6 ± 0.4 FIU/min) and decreased significantly during co-exposure with antioxidants (100 μM melatonin, 25 μM MnTMPyP) and lower levels of O2(60, 40, and 20% O2at 5.3 ± 0.3, 3.3 ± 0.1, and 1.6 ± 0.2 FIU/min, respectively). CA1 cell death after 4 h (ethidium homodimer-1 staining) was greatest in 95% O2and lowest in 40 and 20% O2. CA1 neurons generated evoked action potentials in 20% O2for >4 h, indicating viability at lower levels of oxygenation. We conclude that ·O2−production and cell death in CA1 neurons increases in response to increasing oxygen concentration product (= PO2× time). Additionally, lower levels of oxygen (20–40%) and antioxidants should be considered to minimize superoxide-induced oxidative stress in brain slices.
Changing Motor Synergies in Chronic Stroke
Authors: Dipietro L. , Krebs H. I. , Fasoli S. E. , Volpe B. T. , Stein J. , Bever C. , Hogan N.
Published: June 2007

Synergies are thought to be the building blocks of vertebrate movements. The inability to execute synergies in properly timed and graded fashion precludes adequate functional motor performance. In humans with stroke, abnormal synergies are a sign of persistent neurological deficit and result in loss of independent joint control, which disrupts the kinematics of voluntary movements. This study aimed at characterizing training-related changes in synergies apparent from movement kinematics and, specifically, at assessing: 1) the extent to which they characterize recovery and 2) whether they follow a pattern of augmentation of existing abnormal synergies or, conversely, are characterized by a process of extinction of the abnormal synergies. We used a robotic therapy device to train and analyze paretic arm movements of 117 persons with chronic stroke. In a task for which they received no training, subjects were better able to draw circles by discharge. Comparison with performance at admission on kinematic robot-derived metrics showed that subjects were able to execute shoulder and elbow joint movements with significantly greater independence or, using the clinical description, with more isolated control. We argue that the changes we observed in the proposed metrics reflect changes in synergies. We show that they capture a significant portion of the recovery process, as measured by the clinical Fugl-Meyer scale. A process of “tuning” or augmentation of existing abnormal synergies, not extinction of the abnormal synergies, appears to underlie recovery.
Annealing Kinetic Model Using Fast and Slow Metastable Defects for Hydrogenated-Amorphous-Silicon-Based Solar Cells
Authors: Myong Seung Yeop
Published: June 2007

The two-component kinetic model employing “fast” and “slow” metastable defects for the annealing behaviors in pin-type hydrogenated-amorphous-silicon- (a-Si:H-) based solar cells is simulated using a normalized fill factor. Reported annealing data on pin-type a-Si:H-based solar cells are revisited and fitted using the model to confirm its validity. It is verified that the two-component model is suitable for fitting the various experimental phenomena. In addition, the activation energy for annealing of the solar cells depends on the definition of the recovery time. From the thermally activated and high electric field annealing behaviors, the plausible microscopic mechanism on the defect removal process is discussed.
On a Class of Forward-Backward Stochastic Differential Systems in Infinite Dimensions
Authors: Guatteri Giuseppina
Published: June 2007

We prove that a class of fully coupled forward-backward systems in infinite dimensions has a local unique solution. After studying the regularity property of the solution, we prove that for a peculiar class of systems arising in the theory of stochastic optimal control, the solution exists in arbitrary large time interval. Finally, we investigate the connection between the solution to the systems and a stochastic optimal control problem.
The Factorization Method for Electrical Impedance Tomography Data from a New Planar Device
Authors: Azzouz Mustapha , Hanke Martin , Oesterlein Chantal , Schilcher Karl
Published: June 2007

We present numerical results for two reconstruction methods for a
new planar electrical impedance tomography device. This prototype
allows noninvasive medical imaging techniques if only one side of a patient
is accessible for electric measurements. The two reconstruction methods
have different properties: one is a linearization‐type method that allows
quantitative reconstructions; the other one, that is, the factorization method, is a qualitative one,
and is designed to detect anomalies within the body.
Study of the Effect of Simulated Rain on the Offset Parabolic Antenna at Ku-Band with Different Elevation Angles
Authors: Mostafa H. , Hassan S. I. S. , Mandeep J. S. , Ain M. F. , Khedher H. A.
Published: June 2007

Effect of rain on the receiver antenna is a major factor to degrade the system performance in a frequency above 10 GHz. This paper deals with the wet antenna attenuation at Ku-band with three different frequencies at different rain rates. During the Ku-band propagation experiment, it was discovered that rain water on the antenna caused a significant attenuation. It is necessary to estimate the losses caused by water on the antenna in order to separate these losses from the atmospheric propagation losses. The experiment was done at USM Engineering Campus to study the attenuation for these physical parameters. A Ku-band RF signal was generated by a signal generator and transmitted via horn antenna. The signal was received using a smooth offset antenna of 60 cm by 54 cm (Astro dish) and measured using spectrum analyzer. In order to simulate a rain, pipes with bores of a same distance were implemented. Three cases were considered: in the first case one pipe was used to simulate low rain rate, the second case two pipes were used to simulate medium rain rate, and the third case three pipes were used to simulate heavy rain rate. In addition, the tap was used to control the flow of water in order to get more values of rain rate. The total attenuation of RF signals due to water layer on the feed and on the reflector feed was found to be 3.1 dB at worst case. On the other hand, the attenuation of RF signal due to the feed only was 2.83 dB, so the major attenuation occur was due to feed.
The Effect of PPARα, PPARδ, PPARγ, and PPARpan Agonists on Body Weight, Body Mass, and Serum Lipid Profiles in Diet-Induced Obese AKR/J Mice
Authors: Harrington W. Wallace , Britt Christy S. , Wilson Joan G. , Milliken Naphtali O. , Binz Jane G. , Lobe David C. , Oliver William R. , Lewis Michael C. , Ignar Diane M.
Published: June 2007

Activation of peroxisome proliferator-activated receptor (PPAR)α,δ, andγsubtypes increases expression of genes involved in fatty acid transport and oxidation and alters adiposity in animal models of obesity and type-2 diabetes. PPARpan agonists which activate all three receptor subtypes have antidiabetic activity in animal models without the weight gain associated with selective PPARγagonists. Herein we report the effects of selective PPAR agonists (GW9578, a PPARαagonist, GW0742, a PPARδagonist, GW7845, a PPARγagonist), combination of PPARαandδagonists, and PPARpan (PPARα/γ/δ) activators (GW4148 or GW9135) on body weight (BW), body composition, food consumption, fatty acid oxidation, and serum chemistry of diet-induced obese AKR/J mice. PPARαor PPARδagonist treatment induced a slight decrease in fat mass (FM) while a PPARγagonist increased BW and FM commensurate with increased food consumption. The reduction in BW and food intake after cotreatment with PPARαandδagonists appeared to be synergistic. GW4148, a PPARpan agonist, induced a significant and sustained reduction in BW and FM similar to an efficacious dose of rimonabant, an antiobesity compound. GW9135, a PPARpan agonist with weak activity at PPARδ, induced weight loss initially followed by rebound weight gain reaching vehicle control levels by the end of the experiment. We conclude that PPARαand PPARδactivations are critical to effective weight loss induction. These results suggest that the PPARpan compounds may be expected to maintain the beneficial insulin sensitization effects of a PPARγagonist while either maintaining weight or producing weight loss.
Cell Cycle Regulatory Proteins in Podocyte Health and Disease
Authors: Marshall Caroline B. , Shankland Stuart J.
Published: June 2007

The glomerular visceral epithelial cell, or podocyte, is a highly specialized and terminally differentiated cell that is fundamental to the integrity of the glomerular filtration barrier and functions to prevent urinary protein leakage and to oppose intracapillary hydrostatic pressure. Common to many human kidney diseases and experimental animal models is a strong association between podocyte injury and the development of progressive kidney disease. Studies have shown that a decline in podocyte number strongly correlates with, and likely underlies, proteinuria and the progression to glomerulosclerosis. Maintenance of podocyte differentiation, essential to its normal structure and function, is challenged in the setting of glomerular injury, with very divergent outcomes dependent upon the inciting injury. In response to injury, podocytes may undergo several cell fates, including proliferation, de-differentiation, hypertrophy, apoptosis, or necrosis. Common to these potential outcomes of renal injury is their ultimate regulation at the level of the cell cycle. Positive regulators (cyclins and cyclin-dependent kinases) and negative regulators (cyclin-dependent kinase inhibitors) coordinate the cell cycle. There is now a large body of literature confirming the importance of cell cycle regulatory proteins in the cellular response to injury. Emerging lessons from mouse knockout experiments highlight that the cell cycle machinery operates differently in distinct cell types. Recent studies focusing on the roles of cell cycle regulatory proteins specifically in podocytes have provided important clues on how these proteins operate to constrain cell proliferation and preserve differentiation in health, and how they modulate the dysregulated phenotype in diseased states. In disease, both a failure to regenerate lost podocytes and an inappropriate proliferative response can have profound consequences for glomerular structure and function. Here, we will review the latest advances in understanding the roles of cell cycle regulatory proteins in diseases of the podocyte.
Contribution of the Endothelium to the Glomerular Permselectivity Barrier in Health and Disease
Authors: Ballermann Barbara J.
Published: June 2007

Background: The endothelium that lines glomerular capillaries shares many properties with endothelial cells in general, but unlike most endothelial cells, it is extremely flat and densely perforated by transendothelial cell pores, the fenestrae. Until recently, it was believed that the fenestrae allow free passage of large proteins, and that the glomerular endothelium contributes little to the permselectivity of the glomerular capillary wall. Methods: Key studies addressing the nature of the glomerular capillary endothelium and its contribution to glomerular permselectivity were reviewed. Results: Glomerular endothelial cell flattening and fenestrae formation requires signals from differentiated podocytes, and from the glomerular basement membrane. Deletion of VEGF-A from podocytes prevents flattening and fenestration of glomerular endothelium. Application of VEGF-A to endothelial cells in vivo stimulates fenestrae formation, and neutralization of VEGF-A by soluble VEGF receptor 1 (sFlt-1) or anti-VEGF antibodies results in loss of glomerular fenestrae, and proteinuria. Neutralizing TGF-β1 antibodies, deletion of laminin α3 in mice or laminin β3 in humans cause similar defects. The glomerular endotheliosis lesion of pre-eclampsia is due to the placenta-derived inhibitors sFlt-1 and sEndoglin, which block the VEGF-A/VEGF receptor and TGF-β/endoglin signaling, respectively, causing the loss of glomerular endothelial cell fenestrae, cell swelling and proteinuria. The glomerular endothelium is covered by a glycocalyx that extends into the fenestrae and by a more loosely associated endothelial cell surface layer of glycoproteins. Mathematical analyses of functional permselectivity studies have concluded that the glomerular endothelial cell glycocalyx and its associated surface layer account for the retention of up to 95% of proteins within the circulation. Furthermore, the fenestrae are critical for the maintenance of the high hydraulic conductivity of the glomerular capillary wall, and their loss results in a reduction in the glomerular filtration rate. Conclusions: Loss of GFR and proteinuria can result from glomerular endothelial cell injury.
Alport Syndrome and Thin Basement Membrane Nephropathy
Authors: Thorner Paul Scott
Published: June 2007

Both Alport syndrome and thin basement membrane nephropathy (TBMN) can be considered as genetic diseases of the GBM involving the α3/α4/α5 network of type IV collagen. Mutations in any of the COL4A3, COL4A4 or COL4A5 genes can lead to total or partial loss of this network. Males with mutations in the X-linked COL4A5 gene develop Alport syndrome with progressive renal disease and sometimes extra-renal disease. Females who are heterozygous for a COL4A5 mutation are considered to be carriers for X-linked Alport syndrome. Although their clinical course and GBM ultrastructural changes can sometimes mimic TBMN, more often it tends to be more progressive than usually seen in TBMN. Males or females who are heterozygous for COL4A3 or COL4A4 mutations usually manifest as TBMN, with nonprogressive hematuria, while those who are homozygous or combined heterozygotes develop autosomal-recessive Alport syndrome. Thus, individuals with TBMN can be considered to be carriers for autosomal-recessive Alport syndrome, but there remain some exceptions in which patients heterozygous for COL4A3 or COL4A4 mutations develop autosomal-dominant Alport syndrome. Distinguishing between all these groups of patients requires a combination of family history and a renal biopsy for electron microscopic examination of the GBM and immunohistochemical staining of the GBM for the α3, α4 and α5 chains of type IV collagen. Mutational analysis of the COL4A3, COL4A4, and COL4A5 genes, whenever it becomes available, will be a valuable adjunct to the diagnostic workup in these patients. Novel therapeutic approaches may one day provide a treatment or cure for these patients, avoiding the need for transplantation and dialysis.
Effect of Lesion Characteristics and Mineralising Solution Type on Enamel Remineralisation in vitro
Authors: Lynch R.J.M. , Mony U. , ten Cate J.M.
Published: June 2007

The aim was to study the effect of lesion preparation technique and solution composition on remineralisation of artificial lesions in vitro. Lesions were prepared with similar total mineral loss, but different mineral distribution, i.e., low (14.0) or high R (34.8) values. Lesions from both groups were remineralised (10 days, 37°C) in two different solutions, with similar supersaturation with respect to hydroxyapatite (St), but calcium:phosphate ratios representing either hydroxyapatite stoichiometry or plaque fluid (PF). Remineralisation was quantified microradiographically, mineral distribution was compared with natural white-spot lesions. Mineral loss and depth decreased significantly, and surface-zone mineral content (Zmax) increased significantly, in all lesions. Overall there was a significant relationship of decreasing remineralisation with increasing Zmax, but not within either lesion type. PF was significantly more efficient than St in high-R lesions, with lesions remineralising almost completely in PF. Remineralisation was not significantly different in PF or St for low-R lesions but in high-R lesions, PF was more efficient than St, possibly through differences in relative saturations with respect to different calcium phosphates. Differences in area:solution ratios and baseline Zmax values may also have explained the different response to PF. Low-R lesions were similar to natural white-spot lesions in terms of mineral distribution, whereas high-R were not. Concluding, both lesion and remineralising solution type had a marked influence on remineralisation. It is proposed that use of low-R lesions would be more appropriate where more physiologically relevant mineral distribution is required, whereas high-R lesions would be appropriate for studying inherent remineralising efficiency.
Intracranial Hemorrhage and Hydrops in the Fetus of a Mother with Thrombocytosis: Implications for Possible Pathogenetic Factors and Therapy
Authors: Kurdoglu Mertihan , Erdem Mehmet , Kurdoglu Zehra , Biri Aydan , Tatli Hayriye , Erdem Ahmet
Published: June 2007

We report a case of prenatally diagnosed intracranial hemorrhage and hydrops in the fetus of a mother with a past history of surgical and medical treatment for gastric lymphoma and having high platelet counts thereafter. To the best of our knowledge, such a complication of maternal thrombocythemia has not been described in the literature. In our opinion, the possible pathophysiology of the disease is based on placental insufficiency due to infarctions and related fetal platelet dysfunction, leading to intracranial hemorrhage with subsequent hydrops fetalis. The trigger in this event appears to be trauma to the maternal abdomen. Certain measures for high-risk mothers such as avoidance of trauma to the abdomen and platelet-lowering medications like interferon-α may be useful for preventing such fetal complications.
Does a Myelomeningocele Sac Compared to No Sac Result in Decreased Postnatal Leg Function following Maternal Fetal Surgery for Spina Bifida Aperta?
Authors: Wilson R. Douglas , Johnson Mark P. , Bebbington Michael , Flake Alan W. , Hedrick Holly L. , Sutton Leslie N. , Adzick N. Scott
Published: June 2007

Objective: A fetus with large sac S1 myelomeningocele (MMC) but bilateral talipes prompted the question, ‘Does the presence or size of an MMC sac affect postnatal leg function?’ Study Design: An MMC database with prenatal, birth, and a minimum of 1-year follow-up evaluation was reviewed. All fetuses had in-utero MMC repair at 20 + 0 to 25 + 6 weeks at a single institution. Fifty-four fetuses had prenatal evaluation, with 48 children completing a birth and a 1-year evaluation of leg function. Results: An MMC sac was present in 38/54 (70%) of fetuses evaluated in-utero and had been present in 35/48 (73%) of children evaluated at 1 year of age. Although leg function evaluated at 1 year was better than expected in the ‘no sac’ group (p = 0.059), this did not reach statistical significance. Conclusion: The presence of an MMC sac may increase postnatal lower limb morbidity.
Gastroschisis: Growth Patterns and a Proposed Prenatal Surveillance Protocol
Authors: Netta Denise A. , Wilson R. Douglas , Visintainer Paul , Johnson Mark P. , Hedrick Holly L. , Flake Alan W. , Adzick N. Scott
Published: June 2007

Objective: To assess intrauterine growth for fetuses with gastroschisis using retrospective serial ultrasound assessment from fetuses diagnosed prenatally with gastroschisis. The growth assessment could be available as a prospective tool to direct an antepartum fetal surveillance protocol. Methods: This is a retrospective review of all cases of gastroschisis evaluated prenatally at a single institution between February 1996 and March 2002. Charts were reviewed for serial ultrasound assessment, gestational age at delivery, mode of delivery, and birth weight. Growth assessment was determined for abdominal circumference, biparietal diameter, head circumference, femur length, and estimated fetal weight (IRB No. 2002-1-2648). Results: Forty patients had delivered by March 2002. One hundred and two ultrasound reports were reviewed. Gastroschisis growth curves showed that the 50th percentile was shifted to the right when compared to normal growth curves for abdominal cicumference, biparietal diameter, head circumference, and femur length. The average birth weight was 2,359 g. Compared with a standard population, 44% (16/36) were below the 5th percentile, 61% (22/36) were below the 10th percentile, and 95% (34/36) were below the 50th percentile for gestational age. The average gestational age at delivery was 36.3 weeks. Mothers were nulliparous in 78%, with a mean age of 21.3 years. Conclusions: (1) Fetuses with gastroschisis show a symmetric intrauterine growth restriction pattern consistent with early development of growth delay; (2) the 50th percentile biometry measurements for the gastroschisis population are shifted to the right on normal fetal growth curves; (3) the birth weight is at or below the 10th percentile in 61% of the newborns with gastroschisis, and (4) an antepartum surveillance protocol is proposed based on growth patterns of fetuses with gastroschisis.
Prenatal Genomic Profiling of Abdominal Wall Defects through Comparative Genomic Hybridization: Perspectives for a New Diagnostic Tool
Authors: Heinrich Juliana Karina Ruiz , Machado Isabela Nelly , Vivas Luciana , Bianchi Maria Otília , Cursino Andrade Kleber , Sbragia Lourenço , Barini Ricardo
Published: June 2007

Objectives: To describe the molecular analysis through comparative genomic hybridization (CGH) of fetuses with gastroschisis, and to observe if this technique could improve the resolution of the conventional cytogenetic techniques. Methods: Amniotic analysis of fetuses with gastroschisis, using both conventional (G-banding) and molecular (CGH) cytogenetics assays. Results: All of the seven fetuses studied displayed a normal G-band karyotype. Six fetuses displayed a normal disomic profile through CGH and one sample has displayed ish cgh enh 3q26→qter result (ICSN). The fetus with this imbalance of chromosome 3 was re-classified as a ruptured omphalocele, instead of gastroschisis, after birth. Conclusions: The molecular investigation through CGH technique can improve the resolution of the conventional karyotye analysis in cases of abdominal wall defects.
Safety of Chorionic Villus Sampling in the Presence of Asymptomatic Subchorionic Hematoma
Authors: Akhlaghpoor Shahram , Tomasian Anderanik
Published: June 2007

Objective: According to our knowledge the safety of chorionic villus sampling (CVS) has not been studied in the presence of subchorionic hematoma (SCH). Our study aimed to evaluate the effects of CVS on the procedure-related fetal loss rate in patients with SCH. Method: Fifty-six patients with asymptomatic SCH (cases) and 986 controls in whom there was no hematoma underwent elective CVS for a prenatal diagnosis of β-thalassemia and were entered into a prospective study. Mean gestational age (±SD) at diagnosis for the case and control groups were 11.07 weeks (±0.95, range 10–13 weeks) and 11.51 weeks (±1.04, range 10–13 weeks), respectively. Procedural fetal loss rates were evaluated in these groups after follow-up until 28 weeks of gestation. Results: The average hematoma volume (±SD) was 1.83 ml (±1.57, range 0.3–10.0 ml). Post-CVS early fetal loss was seen in 3.57% (2/56) of patients in the case group and 1.62% (16/986) of patients in the control group. Late fetal loss (up to the 28th week) in the case and control groups was 8.16% (4/49) and 3.76% (29/771), respectively. Post-CVS early fetal loss was seen in 2.44% (1/41) of patients with small-sized SCH (<20% of gestational sac circumference) and in 6.67% (1/15) of patients with medium-sized SCH (20–50% of gestational sac circumference). Comparison of procedure-related early and late fetal loss in the case and control groups using Fisher’s exact test demonstrated no statistically significant difference (p value = 0.252, p value = 0.128). Difference in CVS-related early fetal loss in small- and medium-sized hematoma groups (6.67 vs. 2.44%) was not significant either (p value = 0.468). Conclusion: We were unable to detect any statistically significant difference in fetal loss rate after performing CVS in patients with SCH in comparison to the control group. However, it seems that fetal loss rate may be higher in the presence of medium-sized (20–50% of gestational sac circumference) SCH and further cases are necessary to evaluate the safety of doing CVS in this group.
Parent-Reported Physician Diagnosis Is an Important Factor in Asthma Management: An Elementary School Survey
Authors: Homnick Douglas N. , DeJong Sandra R.
Published: June 2007

Parent surveys seem to provide sufficient information for asthma case selection. In this study, elementary school children were identified for an asthma education program through a screening questionnaire, followed by a comprehensive family survey. The data were analyzed by groups according to those with parent-reported physician diagnosis or no physician diagnosis. Those with an asthma diagnosis had less nighttime symptoms, less family stress, and more asthma follow-up visits, and were prescribed appropriate medications and peak flow meters more often than those students without a physician diagnosis of asthma. A physician commitment to or recognition of an asthma diagnosis is an important factor in subsequent asthma care.
Familiarity of Pediatricians With Different Commercially Available Neonatal and Infant Formulas
Authors: Teitelbaum Jonathan E. , Lagmay Joanne P.
Published: June 2007

To assess the familiarity of pediatricians with commercially available formulas and their use for cow's milk protein allergy and colic, a list of formulas was generated by visiting several grocery stores. Pediatricians were ask to indicate their familiarity with these and other “specialized” formulas with regard to protein and carbohydrate sources, energy content, hypoallergenicity, and indication for infant colic. The participants answered an average of 46% of the questions correctly. Respondents were very familiar with 27% of the formulas, and unfamiliar with 35%. The highest score was 70%, and 10% of the responders correctly answered 65% or more of the questions. Fifty-one percent correctly identified the protein source of the formulas; 32% correctly identified the carbohydrate source. The energy content of the formulas was correctly identified by 54%. These data suggest that pediatricians have a poor understanding of the content and appropriate use of neonatal and infant formulas.
FTIR Analysis of Chemical Gradients in Thermally Processed Molded Polyurethane Foam
Authors: Hatchett David W. , Kinyanjui John M. , Sapochak Linda
Published: June 2007

Thermally processed PU foams are examined as a function of processing temperatures (25, 45, 65, and 85°C) at the side, middle, and center of a simple cylindrical mold. The PU foams show both chemical and morphological differences as a function of the processing temperature and radial position within the mold. Thermal degradation of uretoneimine structures, the emergence of carbodiimide structures, and extent of reaction of isocyanate groups are measured using photoacoustic FTIR spectroscopy. Chemical gradients and morphology differences between the side, middle, and center of the molded foam are observed for all processing temperatures. The data indicate that thermal activation at the center of the mold is important for samples regardless of processing temperature. Furthermore, in spite of thermal processing at temperatures well above the decomposition of uretoneimine structures (40°C), chemical gradients remain within the simple molded foams.
Cellular PVC-U: Current Technology and Future Challenges
Authors: Thomas N.L.
Published: June 2007

This study discusses the formulation technology involved in the production of rigid PVC foams, and typical formulations for rigid foam sheet and profile are presented. Particular reference is given to acrylic processing aids and their effect on melt extensibility and strength. Measurements carried out using an elongational rheometer have confirmed that melt extensibility and rupture stress are increased with increasing addition level and/or molecular weight of the processing aid used.

The challenges faced by the PVC foam industry are also addressed. These include environmental issues, such as the need to develop formulations with sustainable additives and to increase recycling of PVC products. Future developments include the use of organic-based stabilizers (OBS) and the use of nanofillers.
Comparison of Tibial Graft Fixation between Simulated Arthroscopic and Open Inlay Techniques for Posterior Cruciate Ligament Reconstruction
Authors: Campbell R. Brick , Torrie Alec , Hecker Aaron , Sekiya Jon K.
Published: June 2007

Background

Techniques for reconstruction of the posterior cruciate ligament continue to evolve to improve clinical results. Recent arthroscopic reconstruction methods using tibial inlay grafts require suture fixation to avoid a posterior approach to the knee.

Hypothesis

Early strength of the tibial fixation of posterior cruciate ligament inlay grafts, designed for an arthroscopic approach and using suture fixation, is not significantly different than that of open technique grafts using screw fixation.

Study Design

Controlled laboratory study.

Methods

Six paired human tibias were randomized to a reconstruction using an open inlay technique with two 4.0-mm cancellous lag screws or an instrumented technique suitable for an all-arthroscopic approach using 2 No. 5 Ethibond sutures tied over a button on the anterior tibial cortex. Cyclic testing of each construct was done before loading to failure.

Results

The loads for each group at 3-mm displacement and at 5-mm displacement were not found to be significantly different. Ultimate load for the screw group was 762 N and for the suture group was 582 N (P = .31). Stiffness was 89.8 N/mm for the screw inlays and 85.1 N/mm for the suture inlays (P = .68). Cyclic testing demonstrated no advantages of screw fixation over sutures. No suture failure was noted.

Conclusion

The suture fixation technique for tibial inlay posterior cruciate ligament reconstruction appears to approximate the early strength of screw fixation.

Clinical Relevance

Arthroscopic techniques for tibial inlay reconstruction of the posterior cruciate ligament requiring suture fixation may offer similar initial biomechanical fixation as current open inlay techniques without the need for an open posterior knee approach.
New Models for Thermal Conductivity of Particulate Composites
Authors: Pal Rajinder
Published: June 2007

Three new models for the effective thermal conductivity of concentrated particulate composites are developed using the differential effective medium approach. One model predicts the relative thermal conductivity (Kr) of a particulate composite to be a function of two variables, namely thermal conductivity ratio λ (ratio of dispersed-phase to continuous-phase conductivities) and volume fraction of particles φ. The other two models predict K r to be a function of three variables, namely, λ, φ, and φ m where φm is the maximum packing volume fraction of particles. The proposed models are evaluated using twelve sets of published experimental data on the thermal conductivity of particulate composites, covering broad ranges of λ and φ.
Residual Stress Analysis And Expansion of Plastic Zone in Simple Supported and Clamped Supported Woven Ni—Cr Reinforced Thermoplastic Matrix Composite Laminated Plates
Authors: Aykul Halil , Uzkut Mehmet
Published: June 2007

In this study, a residual stress analysis is carried out on symmetric cross-ply and angle-ply thermoplastic simple supported and clamped supported laminated plates for transverse loading. Low density polyethylene thermoplastic matrix (LDPE) and woven Ni—Cr fibers are used to produce the composite plates by using molds. First order shear deformation theory and nine nodes Lagrangian finite element are used. Mathematical formulation is given for the elasto-plastic stress analysis of a laminated plate for small deformations. Yield points and stresses are obtained for symmetric simple supported and clamped supported laminated plates. Residual stresses in thermoplastic plates are given in the tables. The expansion of plastic zones is illustrated for 50, 100 and 150 loading steps. Yield points and the expansion of plastic zones are compared for different plates. Mechanical properties of a layer are obtained experimentally.
Fire Smart DDE Polymers
Authors: Lyon Richard E. , Speitel Louise , Filipczak Robert , Walters Richard N. , Crowley Sean , Stoliarov Stanislav I. , Castelli Lauren , Ramirez Michael
Published: June 2007

The chemistry and properties of polymers containing the “fire smart” moiety 1,1-dichloro-2,2-diphenylethene (DDE) are described. These polymers are typically derived from the bisphenol of chloral (bisphenol-C/BPC) and are low cost, easily processed, and have good mechanical properties and toughness under normal conditions. Under fire conditions, the DDE group undergoes an intramolecular rearrangement with the elimination of hydrogen chloride (a noncombustible gas) and intermolecular crosslinking to form an aromatic char residue in high yield. The flammability and mechanical properties of DDE-containing polymers are described.
Highly Tough and Highly Transparent Soluble Polybenzoxazoles
Authors: Miyazaki Tatsuya , Hasegawa Masatoshi
Published: June 2007

Semi-cycloaliphatic (semi-alicyclic) polybenzoxazoles (PBOs) were investigated as candidates for flexible plastic substrates for liquid crystal displays (LCDs). PBOs were prepared by the one-pot polycondensation in polyphosphoric acid (PPA) from 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAHP6F) with 1,3- and/or 1,4-cyclohexanedicarboxylic acid (CHDCA). The BAHP6F-based PBOs were soluble in various common organic solvents. In addition, the PBO films showed a relatively a high Tg exceeding 250° C, excellent transparency, and a relatively low value of water absorption ( < 0.5%), simultaneously. The BAHP6F-based PBO films were flexible, but the elongation at break ( Eb ) in the stretching test did not exceed 20%. On the other hand, an ether-containing bis(o-aminophenol), 3,3' -diamino-4,4' -dihydroxydiphenylether (ADPE) exhibited much higher polymerization reactivity with CHDCA than BAHP6F, and as a result led to higher molecular weight PBOs. The ADPE-derived PBO films were relatively tough and showed a very high Eb , which exceeded 50%. However, the values of Tg were lower than those of the BAHP6F-derived PBOs, owing to the presence of the flexible ether linkages in the structure. Copolymerization using BAHP6F and ADPE led to excellent combined properties, namely, high Tg , high transparency, a high degree of toughness, and high solution-processability (solubility). The influence of the PBO preparation routes (one-pot technique or two-step method via thermal cyclization of PBO precursors) on the film transparency and other properties are also discussed. Some of the semi-cycloaliphatic PBOs examined in this work practically attained the target properties required for flexible substrates in LCDs..
Piperazinyl-Modified Polysiloxanes and their Cu (II) Complexes
Authors: Epure Virginia , Hamciuc Viorica , Pricop Lucia , Pinteala Mariana , Airinei Anton , Harabagiu Valeria , Simionescu Bogdan C. , Enescu Daniela , Perichaud Alain
Published: June 2007

The paper deals with the synthesis and physico-chemical characterization of polydimethylsiloxanes modified with piperazinyl ligand groups and of their Cu(II) complexes. 1H NMR, Fourier transform infrared, UV-VIS and electron spin resonance spectroscopy were used to follow the structure of the coordination compounds. Three different types of copper bonding to the macromolecular ligand were identified. An uniform distribution of Cu(II) cations into the polymeric material was evidenced by an environmental scanning electron microscopy/microanalysis by energy dispersive spectrometry combined method.
Photoinduced Optical Anisotropy in New Polymers containing Azobenzene Side Groups
Authors: Sava Ion , Bruma Maria , Köpnick Thomas , Sapich Beate , Wagner Jürgen , Schulz Burkhard , Stumpe Joachim
Published: June 2007

A series of new photosensitive polymers have been synthesized by polycondensation reaction of 2,2-bis{3-amino-4-[( p-oxyhexyloxy- p'-butoxy)azobenzene]-phenylene}-hexafluoropropane or 2,2-bis{3-amino-4-[( p-oxybutyloxy- p'-phenyl)azobenzene]-phenylene}-hexafluoropropane with hexafluoroisopropylidene diphthalic anhydride or with a diacid chloride containing hexafluoroisopropylidene or dimethylsilane groups. These amorphous polymers have good solubility in organic solvents and good film-forming properties. The irradiation of polymer films with linearly polarized visible light causes a reorientation of the azobenzene groups by angular-selective E/Z photoisomerization. Thus, optical anisotropy is induced in the initially isotropic films. The photoinduced dichroism in the films was measured and the results are discussed with respect to the polymer structure.
Published and damned
Authors: Hagerty Bill
Published: June 2007

In a rare interview, Britain’s most controversial newspaper columnist charts his remarkable career and defends himself against charges of right-wing bias, homophobia and supporting the return of capital punishment. “Calling me right wing is lazy,” he protests. “I think labels are meaningless – as I’ve said before, it’s about right and wrong, not Right and Left. When people lose the argument or you expose their argument for the hollow, shallow bollocks that it is, they just lay it on you. I’m big enough and ugly enough to take all the shit, but it depresses me. As far as the Left in Britain is concerned, if you are not with them on every single dot, comma and iota of their agenda, you’re not wrong or misguided – you’re evil. If you don’t buy up the whole ticket, then there’s something wrong with you.” And he says he doubts his columns, in The Sun and now in the Daily Mail, have made much of a difference politically or socially over the close to 20 years he was been writing them, but insists, “That’s not a columnist’s job. Bron [the late Auberon] Waugh always used to say, ‘The job of a columnist is to chivvy things up a bit’. We can say things others can’t, or won’t.”
Why blogs are an open door
Authors: Fletcher Kim
Published: June 2007

Examining how journalists can benefit from blogs on the web, former editor Fletcher writes: “Blogs…tend to be open to the world. So do many areas of the social networking sites. When you create an entry about yourself on MySpace, anyone who visits the site can find you, unless you change the default position in order to make your site private. When you post a piece on Facebook, which has a huge following among university students around the world, it is not open to anyone, but there is not much point in being on it unless you make it open to groups of contemporaries – and once it is open to those groups, it is pretty much open full stop.” And he continues: A walk around the web reveals furious commentary from those who believe the press have no right to seek information in this fashion – and from others who think it would be remarkable if they did not. L J Ulrich, a columnist on The Daily Athenaeum, the newspaper of West Virginia University, writes: ‘Like it or not, Facebook is a perfect starting point for investigations. The system is literally a treasure trove of information: names, addresses, cell phone numbers, political affiliations, interests, hobbies, link-charted contact networks and countless photographs. This type of information makes journalists drool – not just because it is readily available and easy to find, but it has been voluntarily broadcast into cyberspace. Anything found on Facebook is well within the public domain. If it's posted, nobody can cry about how it's used’.”
India's angst — it's access all areas
Authors: Franks Suzanne
Published: June 2007

Following vociferous complaints from India over a recent Big Brother TV series featuring Bollywood “princess” Shilpa Shetty, former BBC current affairs producer Franks writes: “Historically there was a clear distinction between foreign and domestic programmes. In a time when the subjects of a report would often never be likely to see or read it, or at least not until the journalists and crew were far away from the scene, there was an implicit double standard. Journalists reporting about foreign places could get away with more and take greater risks… As the domestic becomes global, this distinction no longer applies. Foreign reporters are vulnerable to what BBC World presenter Nik Gowing refers to as a “howl round”. The subjects of their reporting are likely to have a satellite dish on which they can instantly view the report and form an opinion – and the spread of news material to broadband internet means that even the satellite dish becomes unnecessary. On occasion this has put journalists in a dangerous position – for example, Gowing cites rebel guerrilla leaders who do not like the way they are being portrayed and he urges BBC World to recognise that the subjects of its reporting can all potentially view the output.”
On the Collective Nature of Human Intelligence
Authors: Pentland Alex
Published: June 2007

A fundamental assumption of cognitive science is that the individual is the correct unit of analysis for understanding human intelligence. I present evidence that this assumption may have limited utility, that the social networks containing the individuals are an important additional unit of analysis, and that this “network intelligence” is significantly mediated by non-linguistic processes. Across a broad range of situations these network effects typically predict 40% or more of the variation in human behavior.
Emergence of Mirror Neurons in a Model of Gaze Following
Authors: Triesch Jochen , Jasso Hector , Deák Gedeon O.
Published: June 2007

Gaze following is the ability to redirect one's gaze to the location where another agent is looking. We present a computational model of how human infants or other agents may acquire gaze following by learning to predict the locations of interesting sights from the looking behavior of other agents through reinforcement learning. The model accounts for many findings about the development of gaze following in human infants. During learning, the model develops pre-motor representations that exhibit many properties characteristic of mirror neurons, but they are specific to looking behaviors. The existence of such a new class of mirror neurons is the main prediction of our model. The model also offers a parsimonious account of how these and possibly other mirror neurons may acquire their special response properties. In this account, visual representations of other agents' actions become associated with pre-motor neurons that represent the intention to perform corresponding actions. The model also demonstrates how this development may be obstructed in autism spectrum disorder, giving rise to specific physiological and anatomical differences in the mirror system.
Beyond Euclid's fifth
Authors: Walch Martin
Published: June 2007

This essay is an account of the artist's practice-based research into geometry, optics and drafting techniques, with particular interest in how these systems are being challenged by global information and positioning systems.
Immersed In Time
Authors: Cubitt Sean
Published: June 2007

This essay examines the experience of immersion in time and the curiously contemplative kind of `distraction' that is so carefully and variously evinced in many contemporary art installations.
Development of an Automated Eddy Current Structural Health Monitoring Technique with an Extended Sensing Region for Corrosion Detection
Authors: Sodano Henry A.
Published: June 2007

The process of performing nondestructive evaluation (NDE) on a structural system is a well developed and continuously growing field. One very prominent method of performing NDE on a structure is through the use of eddy currents. Eddy current NDE methods are commonly applied to aircraft during maintenance checks in order to identify the formation of cracks, corrosion, or degradation of rivets. Structural health monitoring (SHM) takes NDE a step further and is a process of periodically or continuously monitoring and assessing the performance and safety of a structural system based on data obtained from a sensing system integrated into the structure. Here a method of integrating an eddy current sensing system into the structure such that the structure can be remotely monitored in an automated way is developed. The development of this sensor technology is novel because it can be automated and has a sensing region far larger than the sensor footprint. While earlier studies have integrated eddy current NDE sensors into various structures, all of these studies have developed sensors that can only detect damage directly under the sensor location, which makes SHM of the structure unrealistic. The eddy current senor is demonstrated to identify both corrosion and damage in the form of a small hole well outside the sensors footprint. Furthermore, the statistical variation in the measurements is shown to be very small making the ability to distinguish real damage from false predictions.
Development of Distributed Long-gage Fiber Optic Sensing System for Structural Health Monitoring
Authors: Li Suzhen , Wu Zhishen
Published: June 2007

The essence of structural health monitoring (SHM) requires an innovative sensing system similar to a human nervous system throughout the whole body to catch comprehensive information without losing structural integrity. In a recent research by the authors, an integrated structural assessment strategy based on distributed strain sensing technologies is proposed [1], which has been dedicated to utilize the strain distribution throughout the full or some partial areas of structures to detect the arbitrary and unforeseen damage. To implement such strategy, a typical distributed fiber optic sensing system is developed by extending the gage length of fiber Bragg grating (FBG) and then arranging the long-gage FBG sensors in series. This article summarizes the packaging design and manufacture method of such long-gage FBG sensors and verifies the performance of the developed sensors and the distributed sensing system by using a series connection of long-gage FBG sensors. Combined with the practical application in steel and reinforced concrete (RC) structures, the efficiency and ascendancy of the proposed distributed fiber optic sensing system in SHM are elaborated.