bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of concerns for software evolution
Authors: Mens Tom , Wermelinger Michel
Published: October 2002

This special issue reports on approaches that apply the idea of separation of concerns to software evolution. In this context, separation of concerns allows us to separate parts of the software that exhibit different rates of change or different types of change. This makes it possible to provide better evolution support for those parts that have a higher change rate, or to provide different evolution techniques for different views on the software. Another common way to achieve separation of concerns is by raising the level of abstraction to the level of software architectures, business rules and metamodels. This makes software evolution more manageable. The above ideas emerged as important conclusions of the workshop on Formal Foundations of Software Evolution, which was co‐located with the Conference on Software Maintenance and Re‐engineering in Lisbon in March 2001. Of the 12 original position papers, five have been selected for revision and inclusion in this special issue of the Journal of Software Maintenance and Evolution. Copyright © 2002 John Wiley & Sons, Ltd.
Change impact analysis to support architectural evolution
Authors: Zhao Jianjun , Yang Hongji , Xiang Liming , Xu Baowen
Published: October 2002

Change impact analysis is a useful technique in software maintenance and evolution. Many techniques have been proposed to support change impact analysis at the code level of software systems, but little effort has been made for change impact analysis at the architectural level. In this paper, we present an approach to supporting change impact analysis at the architectural level of software systems based on an architectural slicing and chopping technique. The main feature of our approach is to assess the effect of changes in a software architecture by analyzing its formal architectural specification, and, therefore, the process of change impact analysis can be automated completely. Copyright © 2002 John Wiley & Sons, Ltd.
Behavioural modelling of long‐lived evolution processes—some issues and an example
Authors: Lehman M. M. , Kahen G. , Ramil J. F.
Published: October 2002

For reasons now well understood, application software that is regularly used for real‐world problem solving must be continually adapted and enhanced to maintain its fitness to an ever‐changing real world, its applications and application domains. This type of activity is termedprogressive. As evolution continues, the complexity (functional, structural) of the evolving system is likely to increase unless work, termedanti‐regressive, is undertaken to control and even reduce it. However, with progressive and anti‐regressive work naturally competing for the same pool of resources, management requires means to estimate the amount of work and resources to be applied to each of the two types. After providing a necessary background, the paper describes a systems dynamics model that can serve as the core of a tool to support decision making regarding the optimal personnel allocation over the system lifetime. The model is provided as an example of the use of formalisms in modelling the behaviour of the evolution process. Copyright © 2002 John Wiley & Sons, Ltd.
Evolution of tuf genes: ancient duplication, differential loss and gene conversion
Authors: Lathe Warren C , Bork Peer
Published: October 2002

The tuf gene of eubacteria, encoding the EF‐tu elongation factor, was duplicated early in the evolution of the taxon. Phylogenetic and genomic location analysis of 20 complete eubacterial genomes suggests that this ancient duplication has been differentially lost and maintained in eubacteria.
Lipolytic enzymes LipA and LipB from Bacillus subtilis differ in regulation of gene expression, biochemical properties, and three‐dimensional structure
Authors: Eggert Thorsten , van Pouderoyen Gertie , Dijkstra Bauke W. , Jaeger Karl-Erich
Published: October 2002

Bacillus subtilis secretes the lipolytic enzymes LipA and LipB. We show here that they are differentially expressed depending on the composition of the growth medium: LipA is produced in rich and in minimal medium, whereas LipB is present only in rich medium. A comparison of biochemical characteristics revealed that LipB is thermostable at pH 11 but becomes thermolabile at pH 5. However, construction of a variant carrying the substitution A76G in the conserved lipase pentapeptide reversed these effects. The atomic coordinates from the LipA crystal structure were used to build a three‐dimensional structural model of LipB, which revealed that 43 out of 45 residues different from LipA are surface‐located allowing to rationalize the differences observed in the substrate preferences of the two enzymes.
Regulation of p85α phosphatidylinositol‐3‐kinase expression by peroxisome proliferator‐activated receptors (PPARs) in human muscle cells
Authors: Rieusset Jennifer , Roques Marina , Bouzakri Karim , Chevillotte Emmanuel , Vidal Hubert
Published: October 2002

Regulation of p85α phosphatidylinositol‐3‐kinase (p85αPI‐3K) expression by peroxisome proliferator‐activated receptor (PPAR) activators was studied in human skeletal muscle cells. Activation of PPARγ or PPARβ did not modify the expression of p85αPI‐3K. In contrast, activation of PPARα increased p85αPI‐3K mRNA. This effect was potentiated by 9‐cis‐retinoic acid, an activator of RXR. Up‐regulation of p85αPI‐3K gene expression resulted in a rise in p85αPI‐3K protein level and in an increase in insulin‐induced PI3‐kinase activity. According to the role of p85αPI‐3K in insulin action, these results suggest that drugs with dual action on both PPARγ and PPARα can be of interest for the treatment of insulin resistance.
Growth kinetics rather than stress accelerate telomere shortening in cultures of human diploid fibroblasts in oxidative stress‐induced premature senescence
Authors: Dumont Patrick , Royer Véronique , Pascal Thierry , Dierick Jean-François , Chainiaux Florence , Frippiat Christophe , de Magalhaes Joao Pedro , Eliaers François , Remacle José , Toussaint Olivier
Published: October 2002

WI‐38 human diploid fibroblasts underwent accelerated telomere shortening (490 bp/stress) and growth arrest after exposure to four subcytotoxic 100 μM tert‐butylhydroperoxide (t‐BHP) stresses, with a stress at every two population doublings (PD). After subcytotoxic 160 μM H2O2 stress or five repeated 30 μM t‐BHP stresses along the same PD, respectively a 322±55 and 380±129 bp telomere shortening was observed only during the first PD after stress. The percentage of cells resuming proliferation after stress suggests this telomere shortening is due to the number of cell divisions accomplished to reach confluence during the first PD after stress.
Prooxidant activity of melatonin promotes fas‐induced cell death in human leukemic Jurkat cells
Authors: Wölfler Albert , Caluba Hans-Christian , Abuja Peter M , Dohr Gottfried , Schauenstein Konrad , Liebmann Peter M
Published: October 2002

The antioxidant activity of melatonin (MEL) has been considered to constitute part of its physiological as well as pharmacological effects. However, as described herein we found a profound prooxidant activity of micro‐ to millimolar concentrations of MEL in the human leukemic Jurkat cell line. This prooxidant effect was increased in glutathione‐depleted cells and counteracted by antioxidants. As a consequence MEL promoted fas‐induced cell death. These data therefore indicate that MEL may be a modulator of the cellular redox status, but does not necessarily act as an intracellular antioxidant.
Physicians' perceptions of menopause and prescribing practices in Morocco
Authors: Obermeyer C.M. , Sahel A. , Hajji N. , Schulein M.
Published: October 2002

Objective: To investigate the prescribing practices of Moroccan physicians around menopause. Methods: A survey was carried out on a representative sample of physicians in the capital city Rabat. The sample included general practitioners, gynecologists, cardiologists and rhumatologists, practicing in both public and private facilities. The instrument consisted of close‐ and open‐ended questions about the socio‐demographic characteristics of physicians, their patient population, their prescribing practices, and their perceptions of menopause and the different medical approaches to managing the symptoms and risks associated with it. Results: Most of the physicians interviewed are positively inclined towards the notion of prevention and in favor of hormonal treatment, and approximately half report that they have prescribed hormone therapy. Gynecologists and male physicians prescribe hormones more frequently, as well as physicians who are at private facilities. These findings are discussed in relation to the physicians' perceptions of the menopause transition. Conclusion: There are considerable variations in prescribing practices and perceptions of menopause among Moroccan physicians.
Route of breech delivery and maternal and neonatal outcomes
Authors: Sanchez‐Ramos L , Wells T.L , Adair C.D , Arcelin G , Kaunitz A.M , Wells D.S
Published: October 2002

Objective: To compare maternal and neonatal outcomes in elective cesarean vs. attempted vaginal delivery for breech presentation at or near term. Methods: We reviewed the maternal and neonatal charts of all singleton breech deliveries of at least 35 weeks’ gestation or 2000 g delivered between 1986 and 1997 at our institution. Patients delivered by elective cesarean were compared to those attempting a vaginal delivery. The neonatal outcomes analyzed were: corrected mortality; Apgar scores less than 7 at 5 min; abnormal umbilical cord blood gases; birth trauma; and admissions to the intensive care nursery. Maternal morbidity was also assessed and compared. Results: Of 848 women meeting criteria for evaluation, 576 were delivered by elective cesarean while 272 attempted a vaginal delivery. Of 272 women undergoing a trial of labor, 203 (74.6%) were delivered vaginally, while 69 (25.4%) failed an attempt at vaginal delivery and underwent a cesarean. When comparing patients delivered by elective cesarean with those attempting a vaginal delivery, no significant differences were noted in neonatal outcomes. However, maternal morbidity was higher among women delivered by cesarean, regardless of the indications for the procedure. Similar neonatal and maternal results were noted when nulliparous patients were analyzed separately. Conclusions: Cesarean delivery of selected near‐term infants presenting as breech is associated with increased maternal morbidity without corresponding improvement in neonatal outcomes.
Brachial plexus injury and obstetrical risk factors
Authors: Bar J , Dvir A , Hod M , Orvieto R , Merlob P , Neri A
Published: October 2002

Objective: To determine whether known historical risk factors of brachial plexus injury differ between affected neonates and healthy controls. Methods: The files of all 62 children with Erb's palsy who were diagnosed after birth were reviewed. The control group consisted of 124 randomly selected uninjured infants born within the same period. Results: Compared with the control group, the mothers of the neonates with brachial plexus injury were found to be significantly older (32.1±5.2 years vs. 28.9±5.8 years, P=0.01), and had a significantly higher incidence of diabetic pregnancy (69% vs. 14.5%, P=0.001); the infants had a significantly higher mean birth weight (3846±576 g vs. 3220±582 g, P=0.0001) and higher incidence of birth weight ≥4000 g (27% vs. 4.8%, P=0.0001). Two of the infants in the study group (3.2%) were born by elective cesarean section. Conclusions: Brachial plexus injury is associated with several non‐predictable or preventable risk factors.
Cervical cancer detection by hybrid capture™ and evaluation of local risk factors
Authors: Lorenzato F. , Singer A. , Mould T. , Santos L.C. , Maia A. , Cariri L.
Published: October 2002

The city of Recife, northeastern Brazil, is reported to have the highest incidence of cervical cancer worldwide (83.2/100 000 women). Objective: To evaluate the efficacy of Hybrid Capture™ I (HC I) in cervical cancer detection and some risk factors in Recife. Method: Cervical scrapes for HC I analysis followed by colposcopy were collected from 140 women (70 with cervical cancer and 70 with normal cervix) from three screening services in Recife. Result: HC I sensitivity and specificity were 82.9 and 41.4%, respectively. The odds ratios for cervical cancer when Gesta ≥5 and vaginal parity ≥4 were, respectively, 5.30 and 4.27. Conclusion: HC I is a moderately sensitive method to detect cervical cancer, but it does not seem to be useful as a primary screening tool for it's low specificity. Early pregnancy, high Gesta/Para and living in rural areas were important local risk factors.
Pregnancy outcome in women with morbid obesity
Authors: Kumari A.S.
Published: October 2002

Objective: To study the effects of morbid obesity defined as a first trimester maternal body mass index of >40 on the perinatal outcome. Methods: One hundred and eighty‐eight singleton pregnancies of women with first trimester BMI >40 who delivered at Al‐Mafraq Hospital, Abu Dhabi during 1996–1998 were studied. A control group of normal body mass index matched for age and parity were selected and the perinatal variables were compared between groups. Morbidly obese women with diabetes and hypertension antedating the index pregnancy were later excluded and the data were re‐analyzed. Results: Morbidly obese women were noted to have significantly adverse perinatal outcomes including hypertensive disorders of pregnancy (28.8 vs. 2.9%, P<0.0001), gestational diabetes (24.5 vs. 2.2%, P<0.0001), cesarian section (15.2 vs. 9.3%, P<0.05) and macrosomia (32.6 vs. 9.3%, P<0.001) compared to non‐obese women. However, we noted a significantly lower rate of prematurity in the obese group (0.5 vs. 5.3%, P<0.001). Even when morbidly obese women with (a) diabetes and hypertension antedating the index pregnancy and (b) those who developed gestational diabetes and/or pregnancy‐induced hypertension during the index pregnancy were excluded from the analysis, significant differences in the perinatal outcomes still persisted. Conclusion: Morbid obesity appears to be an independent risk factor for adverse perinatal outcome.
Misoprostol for prevention of postpartum hemorrhage
Authors: Bugalho A. , Daniel A. , Faúndes A. , Cunha M.
Published: October 2002

Objective:To compare the effectiveness of 400 μg rectal misoprostol in 5 cm3of saline with oxytocin 10 IU, i.m., in reducing bleeding during the third stage of labor.Design:A double blind, randomized, clinical trial including 663 women with uncomplicated vaginal delivery who received misoprostol (n=324) or oxytocin (n=339).Main outcome measures:Changes in hemoglobin and hematocrit from before to 72 h postpartum; blood loss during the third stage; duration of the third stage of labor; need for additional oxytocic drug; frequency of requisition and of administration of blood; changes in blood pressure; and occurrence of side effects.Results:No significant differences were observed between groups, before and 72 h postpartum, in mean hemoglobin and hematocrit, on volume of blood loss and duration of third stage of labor. The incidence of shivering and mean temperature (P<0.01) was significantly greater among women receiving misoprostol than oxytocin.Conclusions:Misoprostol administered as a micro‐enema, 400 μg in 5 ml of saline during the third stage of labor, appears to be as effective as oxytocin 10 IU, i.m., but misoprostol produced more side effects than oxytocin.
Fetal dysmorphism in spontaneous abortions in a Mexican population
Authors: Arteaga M. , Garcı́a‐Peláez I. , Cornejo L.R. , Chavira S. , Saavedra D.
Published: October 2002

Objective: The purpose of this research was to find out the frequency and type of fetal dysmorphism in spontaneous abortions among the Mexican population. Method: A prospective study was carried out in all the cases of spontaneous miscarriages occurring at the ‘Dr. Manuel Gea González’ General Hospital in Mexico City, from July 1989 to June 1999. Result: Two hundred and one empty sacs and 1555 well‐defined embryos or fetuses were analyzed. Dysmorphism was observed in 48% of the cases, malformations being the most frequently found. Among malformations the largest group corresponded to morphological alterations not recognized in the postnatal life, facial clefts and closure defects of the abdominal wall were the known malformations of the postnatal period most frequently found. The most common syndromic entities were suggestive of bone dysplasia and Turner phenotype. Conclusion: The frequency of fetal dysmorphism in spontaneous abortions is higher than in new borns. Its diagnosis is very important for genetic counseling.
Investigation of the uterine cavity and fallopian tubes using three‐dimensional saline sonohysterosalpingography
Authors: Sankpal R.S. , Confino E. , Matzel A. , Cohen L.S.
Published: October 2002

Objective: to compare three‐dimensional saline sonohysterosalpingography (SHSG) to X‐ray hysterosalpingography (HSG) for the evaluation of the uterine cavity and fallopian tubes. Patient population: Fifteen infertile women on whom X‐ray HSG had been performed within 1 year prior to this study. Method: Fifteen infertile women underwent three‐dimensional power Doppler examination of the uterus and fallopian tubes with three‐dimensional SHSG during the follicular phase. Distension was achieved using sterile saline injected through a 5 French HSG catheter. Peritoneal accumulation of free fluid surrounding the ovary and tube was required for a diagnosis of a patent tube. Fluid accumulation in the cul‐de‐sac without visualization of the tubes was considered consistent with at least one tube being patent. Results: three‐dimensional saline SHSG was completed in 14 patients. One patient had cervical stenosis and the procedure could not be performed. No significant intrauterine pathology was identified by either X‐ray HSG or sonography. Three‐dimensional saline SHSG made false positive diagnoses of tubal occlusion in four out of seven fallopian tubes (57%). The sensitivity and specificity for detecting tubal occlusion was 75 and 83%, respectively, with a positive predictive value of 40% and negative predictive value of 95%. Detection of fallopian tube architecture was not possible with three‐dimensional saline SHSG in any patient. Simultaneous use of three‐dimensional Doppler did not clearly identify the flow of saline through the fallopian tubes. Conclusions: transvaginal three‐dimensional saline SHSG provides good visualization of the uterine cavity and myometrial walls in three orthogonal planes. However, it does not diagnose tubal occlusion or depict architecture of the fallopian tube as accurately as X‐ray HSG. Although we were able to visualize the distal fallopian tube and fimbria with real‐time imaging, we were not able to satisfactorily image the proximal tube with three‐dimensional power Doppler. This technique may be reserved as an initial screening test to evaluate the uterine cavity and test patency. Patients at high risk for tubal disease by history or with suspected tubal occlusion on three‐dimensional saline SHSG should be evaluated by either X‐ray HSG or laparoscopy with chromopertubation. Further improvements of three‐dimensional technology and contrast materials will, it is hoped, make this method comparable to X‐ray HSG.
An appraisal of the role of laparoscopy: past, present, and future
Authors: Brosens I.A , Campo R , Gordts S , Brosens J.J
Published: October 2002

Objective: To review the role of laparoscopy in the management of chronic pelvic pain (CPP). Method: A literature search was conducted to obtain a clear perspective on the role of laparoscopy for CPP. Results: Laparoscopy has been widely used as a diagnostic tool in CPP, but often falls short in defining the type and activity of ectopic endometrial‐like tissue. Because pelvic endometriosis includes a wide range of lesions, histological confirmation varies greatly. The evaluation of peritoneal endometriosis at laparoscopy can be misleading. In one study 43% of the patients with minimal or mild endometriosis were found at second‐look laparoscopy to be free of lesions. Finally, laparoscopy is not without major complications and the risk of undiagnosed bowel injury is likely to be underestimated. Conclusion: The diagnosis of endometriosis can no longer be limited to the visual inspection of the pelvis but requires a wider range of investigations to assess the reproductive system and the role of endometriotic lesions and adhesions in CPP.
Maternal-infant transmission of hepatitis C virus infection
Authors: Roberts Eve A. , Yeung Latifa
Published: October 2002

Mother-to-infant transmission of hepatitis C virus (HCV) is comparatively uncommon. The prevalence of antibody to HCV (anti-HCV) in pregnant women is 0.1% to 2.4%, although in some endemic areas it is much higher. The proportion of women with anti-HCV who have active infection with viremia is 60% to 70%. Transmission of HCV occurs only when serum HCV RNA is detectable and may be related to higher levels (above 106 copies per mL). The rate of mother-to-infant transmission is 4% to 7% per pregnancy in women with HCV viremia. Co-infection with human immunodeficiency virus (HIV) increases the rate of transmission 4 to 5 fold. The actual time and mode of transmission are not known. Elective Cesarean section is not recommended for women with chronic HCV infection alone. The role of treatment to prevent transmission is limited by the fetal toxicity of currently available medications for hepatitis C. Breast feeding poses no important risk of HCV transmission if nipples are not traumatized and maternal hepatitis C is quiescent. Pregnant women at high risk for HCV infection should be screened for anti-HCV, and HCV RNA testing should be performed if anti-HCV is positive. Infants of women with hepatitis C should be tested for HCV RNA on two occasions, between the ages of 2 and 6 months and again at 18 to 24 months, along with serum anti-HCV. The natural history of mother-to-infant hepatitis C remains uncertain, especially the course in the first year of life when some infants appear to have spontaneous resolution.
Future therapy of hepatitis C
Authors: McHutchison John G. , Patel Keyur
Published: October 2002

Currently available therapies for the treatment of chronic hepatitis C are effective in half of patients, but are expensive, often poorly tolerated, and unsuitable for certain patient populations. The ideal therapy would be highly effective, orally bioavailable, have minimal side effects, be cost effective, and suitable for the majority of patients with hepatitis C. Recent advances in understanding the replication cycle of hepatitis C virus (HCV) and structural, crystallographic definitions of components of the viral polyprotein have improved the prospects for development of novel therapies. The lack of a small animal model of HCV infection continues to hamper progress in the preclinical evaluation of new antivirals and vaccines. Strategies to enhance response to current therapies include the development of novel interferons and delivery systems, nucleoside analogues that have reduced hemolysis compared with ribavirin, inosine 5’ monophosphate dehydrogenase inhibitors, and other immunomodulators that are being evaluated as adjunctive therapy to interferon-based regimens. Compounds in preclinical or early phase human trials include small molecules that inhibit virus specific enzymes (such as the serine proteases, RNA polymerase and helicase), or those that prevent translation initiation (such as antisense molecules and ribozymes). Antifibrotic agents are also being developed in an attempt to prevent disease progression in patients in whom HCV RNA cannot be eradicated. While the advent of these newer compounds represent an exciting phase in the treatment of HCV, their safety and efficacy need to be established. Most of these newer therapies are unlikely to be available for routine clinical use in the next 3 to 5 years.
Hepatocellular carcinoma and hepatitis C in the United States
Authors: El-Serag Hashem B.
Published: October 2002

Chronic infection with hepatitis C virus (HCV) is a major risk factor for development of hepatocellular carcinoma (HCC). In general, HCC develops only after 2 or more decades of HCV infection and the increased risk is restricted largely to patients with cirrhosis or advanced fibrosis. Factors that predispose to HCC among HCV-infected persons include male sex, older age, hepatitis B virus (HBV) coinfection, heavy alcohol intake, and possibly diabetes and a transfusion-related source of HCV infection. Viral factors play a minor role. The likelihood of development of HCC among HCV-infected persons is difficult to determine because of the paucity of adequate long-term cohort studies; the best estimate is 1% to 3% after 30 years. Once cirrhosis is established, however, HCC develops at an annual rate of 1% to 4%. Successful antiviral therapy of patients with HCV-related cirrhosis may reduce the future risk for HCC. The incidence of and mortality caused by all HCC has doubled in the United States over the past 25 years, an increase that has affected all ethnic groups, both sexes, and younger age groups. Given the current prevalence of HCV infection among persons 30 to 50 years of age, the incidence and mortality rates of HCC are likely to double in the United States over the next 10 to 20 years. Future research should focus on improving understanding of the incidence and risk factors for HCC, causes of HCV-related carcinogenesis, means of early detection, and better treatment for HCC.
Alcohol use and hepatitis C
Authors: Peters Marion G. , Terrault Norah A.
Published: October 2002

Excess alcohol consumption can worsen the course and outcome of chronic hepatitis C. It is important to distinguish between alcohol abuse, which must be treated on its own merits, and the effect of alcohol use on progression, severity, and treatment of hepatitis C. Most studies on the effects of alcohol on hepatitis C have focused on patients with high levels of daily alcohol intake. Indeed, the adverse effects of light and moderate amounts of alcohol intake on hepatitis C virus (HCV) infection have not been clearly shown, and only limited studies have been performed. Sex differences exist in the effect of alcohol on fibrosis as well as on the severity of hepatitis C. Alcohol use has been reported to be associated with lower responses to therapy and, in some studies, higher HCV RNA levels and increased HCV quasi-species. Few studies address the treatment of hepatitis C in the alcoholic individual or determine the effect of continued light or moderate alcohol use on the outcome of treatment response. In summary, many critical questions remain regarding the interactions between alcohol and hepatitis C. Currently, the evidence from the literature shows that heavy alcohol intake worsens the outcome of HCV infection. The literature is inadequate to provide definitive recommendations regarding the effect of light to moderate alcohol use in patients with hepatitis C.
Treatment of patients with hepatitis C and cirrhosis
Authors: Wright Teresa L.
Published: October 2002

Recommendations for treatment of hepatitis C in patients with cirrhosis are difficult. Few prospective studies have focused on treatment of patients with advanced disease, and response rates appear to be lower and serious side effects more frequent in patients with cirrhosis. In patients with compensated cirrhosis, combination therapy with interferon alfa (3 million units [MU] 3 times a week) and ribavirin (1,000 or 1,200 mg/d) results in a sustained virological response (SVR) in 33% to 41% of patients. Responses to combination therapy are not significantly higher using peginterferon alfa 2a (180 μg/wk; 43%) or peginterferon alfa 2b (1.5 μg /kg/wk; 44%) compared with standard interferon. In using peginterferon in combination therapy, the benefits of once weekly dosing need to be weighed against the higher risks of cytopenias and greater costs with the pegylated formulations. Combination therapy results in some degree of histological improvement even in patients who are virological non-responders. These findings provide the scientific basis for ongoing studies of maintenance therapy with peginterferon to prevent complications of cirrhosis in non-responder patients with hepatitis C. Recommendations for management of decompensated cirrhosis and of recurrent hepatitis C after liver transplantation are difficult because of limitations of data, most of which are derived from uncontrolled case series. Combination therapy is poorly tolerated in both groups and rates of response are low. Thus, while the medical need is great, treatment of patients with decompensated cirrhosis or with recurrent hepatitis C after transplantation should be undertaken cautiously and only within the confines of prospective clinical trials.
Fibrosis and disease progression in hepatitis C
Authors: Marcellin Patrick , Asselah Tarik , Boyer Nathalie
Published: October 2002

The progression of fibrosis in chronic hepatitis C determines the ultimate prognosis and thus the need and urgency of therapy. Fibrogenesis is a complex dynamic process, which is mediated by necroinflammation and activation of stellate cells. The liver biopsy remains the gold standard to assess fibrosis. Scoring systems allow a semiquantitative assessment and are useful for cross-sectional and cohort studies and in treatment trials. The rate at which fibrosis progresses varies markedly between patients. The major factors known to be associated with fibrosis progression are older age at infection, male gender, and excessive alcohol consumption. Viral load and genotype do not seem to influence significantly the progression rate. Progression of fibrosis is more rapid in immunocompromised patients. Hepatic steatosis, obesity, and diabetes may also contribute to more rapid progression of fibrosis. There are no tests that reliably predict the rate of progression of fibrosis in an individual patient. High serum alanine aminotransferase (ALT) levels are associated with a higher risk of fibrosis progression, and worsening of fibrosis is uncommon in patients with persistently normal serum aminotransferase levels. Serum markers for fibrosis are not reliable and need to be improved and validated. Liver biopsy provides the most accurate information on the stage of fibrosis and grade of necroinflammation, both of which have prognostic significance. Repeating the liver biopsy, 3 to 5 years after an initial biopsy is the most accurate means of assessing the progression of fibrosis.
Microwave measurement of the permittivity for high dielectric constant materials using an extra-cavity evanescent waveguide
Authors: Ni Erhu , Jiang Xing
Published: October 2002

This article is concerned to a TE01n mode resonant cavity coupled through a hole located in the center of the end wall to a cylindrical waveguide (equal in diameter to hole) supporting the evanescent TE01 mode. When the evanescent guide contains a dielectric sample, propagation of the TE01 wave will be permitted in the dielectric filled part. The air filled part in front of the sample is used to adjust the coupling level; the air filled part of the sufficient length behind the sample is used to form a matched reactance termination, otherwise a metal block is inserted to form a short-circuit termination or a reactance termination. It is shown that while using these arrangements quite a large change in the resonant length (or resonant frequency) and Q factor of the cavity resonator will be obtained, when the sample possessed suitable electric thickness is inserted into the evanescent guide. Therefore, it should be capable of yielding accurate values of the complex permittivity for high dielectric constant materials. Fundamental principles and theoretical error of measurements of the complex permittivity as a function of the electric thickness in the sample due to the uncertainty of measurements in the resonant length and Q factor are discussed. The measured results at some frequencies of the X band and Ka band on two ceramics are given. The technique is compared with the parallel-plate method, showing that the dielectric properties have comparable values in both methods.
Coupled-cluster Raman intensities: Assessment and comparison with multiconfiguration and density functional methods
Authors: Neugebauer Johannes , Reiher Markus , Hess Bernd A.
Published: October 2002

An extensive study of static and dynamic Raman intensities is presented for normal vibrations of small molecules obtained with different correlated quantum chemical methods: namely, coupled-cluster, multiconfiguration self-consistent-field, and density functional theories. While this is the first systematic study of coupled-cluster (CC) Raman intensities considering also the dispersion effect for molecules with more than two atoms, another purpose of this study is the analysis of the accuracy of density functional Raman activities with respect to those from highly correlated ab initio methods in order to evaluate the validity of density functional theory for the calculation of Raman spectra for large molecules. The density functional intensities compare sufficiently well with those from ab initio methods. While the dynamic multiconfigurational intensities always compare well with the experimental values, they are usually smaller than those from density functional and coupled-cluster theories. The Raman intensities obtained from static coupled-cluster calculations are in better agreement with experiment than those from dynamic calculations, which should yield improved results as the dispersion effect is taken into account. Furthermore, Raman intensities obtained from the CC2 model are compared to those from CCSD calculations. It is found that the CC2 Raman activities deviate from the CCSD reference data. Particularly for the coupled-cluster Raman intensities the widely used Sadlej basis set leads to results which can be significantly improved on by using larger basis sets.
Bifurcation tunneling dynamics in the water trimer
Authors: Keutsch Frank N. , Saykally Richard J. , Wales David J.
Published: October 2002

Recent far-infrared vibration–rotation–tunneling experiments have probed intricate details of the hydrogen bond tunneling dynamics in the water trimer through excitation of intermolecular vibrational transitions to states of sequentially increasing energy. The experimentally observed bifurcation splitting in the water trimer evolves from an equally spaced quartet in the vibrational ground state to a slightly asymmetrical quartet for intermediate torsional vibrational states lying below 100 cm−1. Even more asymmetric bifurcation splittings have been observed in the out-of-plane librational band of (H2O)3 near 520 cm−1. These patterns may be caused by the bifurcation and flip rearrangements becoming comparable in magnitude. Alternatively, some of the data can be fitted by introducing tunneling matrix elements corresponding to multiple elementary rearrangements. Analysis of the observed bifurcation tunneling splittings of (D2O)3 confirms that the dominant bifurcation pathway includes the torsional flipping motion of the neighboring water molecules. Quantification of the bifurcation matrix elements of (D2O)3 furthermore reveals that these vary within each torsional manifold.
Induced current damping for the suspension system of a gravitational-wave detector
Authors: Somiya K. , Tariq H. , Miyakawa O. , Heinzel G. , Mio N. , Kawamura S.
Published: October 2002

The damping technique is necessary to control a suspended mass used for an interferometric gravitational wave detector. Here we introduce a new damping method, called “induced current damping,” which has a simple mechanical and electric design and a desirable attenuation performance of pendulum. The fundamental concept of the induced current damping is a conversion of the mass motion to the Joule heat of an external coil. To realize an optimal Joule heat the effective internal resistance of the coil used for the induced current damping is reduced by connecting a negative resistance circuit to the coil. We built a one-dimensional suspension system with the induced current damping and demonstrated that the system worked as expected.
Space-based magnetometers
Authors: Acuña Mario H.
Published: October 2002

The general characteristics and system level concepts for space-based magnetometers are presented to illustrate the instruments, principles, and tools involved in making accurate magnetic field measurements in space. Special consideration is given to the most important practical problems that need to be solved to ensure the accuracy of the measurements and their overall impact on system design and mission costs. Several types of instruments used to measure magnetic fields aboard spacecraft and their capabilities and limitations are described according to whether they measure scalar or vector fields. The very large dynamic range associated with magnetic fields of natural origin generally dictates the use of optimized designs for each particular space mission although some wide-range, multimission magnetometers have been developed and used. Earth-field magnetic mapping missions are the most demanding in terms of absolute accuracy and resolution, approaching <1 part in 100 000 in magnitude and a few arcsec in direction. The difficulties of performing sensitive measurements aboard spacecraft, which may not be magnetically clean, represent a fundamental problem which must be addressed immediately at the planning stages of any space mission that includes these measurements. The use of long, deployable booms to separate the sensors from the sources of magnetic contamination, and their impact on system design are discussed. The dual magnetometer technique, which allows the separation of fields of external and spacecraft origin, represents an important space magnetometry tool which can result in significant savings in complex contemporary spacecraft built with minimum magnetic constraints. Techniques for in-flight estimation of magnetometer biases and sensor alignment are discussed briefly, and highlight some basic considerations within the scope and complexity of magnetic field data processing and reduction. The emerging field of space weather is also discussed, including the essential role that space-based magnetic field measurements play in this complex science, which is just in its infancy. Finally, some considerations for the future of space-based magnetometers are presented. Miniature, mass produced sensors based on magnetoresistance effects and micromachined structures have made significant advances in sensitivity but have yet to reach the performance level required for accurate space measurements. The miniaturization of spacecraft and instruments to reduce launch costs usually results in significantly increased magnetic contamination problems and degraded instrument performance parameters, a challenge that has yet to be solved satisfactorily for “world-class” science missions. The rapidly disappearing manufacturing capabilities for high-grade, low noise, soft magnetic materials of the Permalloy family is a cause of concern for the development of high performance fluxgate magnetometers for future space missions.
High precision, fast ultrasonic thermometer based on measurement of the speed of sound in air
Authors: Huang K. N. , Huang C. F. , Li Y. C. , Young M. S.
Published: October 2002

This study presents a microcomputer-based ultrasonic system which measures air temperature by detecting variations in the speed of sound in the air. Changes in the speed of sound are detected by phase shift variations of a 40 kHz continuous ultrasonic wave. In a test embodiment, two 40 kHz ultrasonic transducers are set face to face at a constant distance. Phase angle differences between transmitted and received signals are determined by a FPGA digital phase detector and then analyzed in an 89C51 single-chip microcomputer. Temperature is calculated and then sent to a LCD display and, optionally, to a PC. Accuracy of measurement is within 0.05 °C at an inter-transducer distance of 10 cm. Temperature variations are displayed within 10 ms. The main advantages of the proposed system are high resolution, rapid temperature measurement, noncontact measurement and easy implementation.
On line multitarget selection device with multiple facilities
Authors: Roy Subir , Das Avijit , Ibomcha N. , Bhandari R. K.
Published: October 2002

We have developed a multitarget holding device as a subsystem for atomic or nuclear physics experiments. A permanent magnet stepper motor rotates the device for target selection without breaking the vacuum. The target holder is potentially isolated from the rest of the system with the help of a Teflon block. The device and its controlled circuits are described below.
Relaxation of the C–H stretching fundamental vibrations of CHI3, CH2I2, and CH3I in solution
Authors: Heckscher Max M. , Sheps Leonid , Bingemann Dieter , Crim F. Fleming
Published: October 2002

Transient electronic absorption spectroscopy monitors the population of intermediate states in the vibrational energy relaxation of the iodo-substituted methanes, CHI3, CH2I2, and CH3I in solution after excitation of the fundamental C–H stretching vibration. These experiments give times for both intra- and intermolecular energy flow for each molecule. The trend in intramolecular vibrational energy redistribution (IVR) times shows that the local vibrational state structure around the initially prepared states in each molecule, not the overall state density, controls IVR. A comparison of experiments in the solvents chloroform and acetone reveals the solvent role in IVR and shows a strong solvent effect on the intermolecular energy transfer.
In situ laser annealing system for real-time surface kinetic analysis
Authors: Wang Q. , Sun Y.-M. , Zhao W. , Campagna J. , White J. M.
Published: October 2002

For real-time analysis during thermal annealing, a continuous wave CO2 infrared laser was coupled to a surface analysis system equipped for x-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The laser beam was directed into the vacuum chamber through a ZnSe window to the back side of the sample. With 10 W laser output, the sample temperature reached 563 K. The chamber remained below 10−8 Torr during annealing and allowed XPS and ISS data to be gathered as a function of time at selected temperatures. As a test example, real time Cu2O reduction at 563 K was investigated.
A nearly real-time high temperature laser–plasma diagnostic using photonuclear reactions in tantalum
Authors: Spencer I. , Ledingham K. W. D. , Singhal R. P. , McCanny T. , McKenna P. , Clark E. L. , Krushelnick K. , Zepf M. , Beg F. N. , Tatarakis M. , Dangor A. E. , Edwards R. D. , Sinclair M. A. , Norreys P. A. , Clarke R. J. , Allott R. M.
Published: October 2002

A method of measuring the temperature of the fast electrons produced in ultraintense laser–plasma interactions is described by inducing photonuclear reactions, in particular (γ,n) and (γ,3n) reactions in tantalum. Analysis of the γ rays emitted by the daughter nuclei of these reactions using a germanium counter enables a relatively straightforward near real-time temperature measurement to be made. This is especially important for high temperature plasmas where alternative diagnostic techniques are usually difficult and time consuming. This technique can be used while other experiments are being conducted.
Wide-dynamic-range “neutron bang time” detector on OMEGA
Authors: Stoeckl C. , Glebov V. Yu. , Zuegel J. D. , Meyerhofer D. D. , Lerche R. A.
Published: October 2002

A simple, low-cost “neutron bang time” detector has been implemented on the OMEGA laser system to measure the average time of neutron emission from inertial confinement fusion targets. This detector uses fast plastic scintillators coupled to photomultiplier tubes. A fast digital real-time oscilloscope records the signals. Absolute timing accuracies of better than 100 ps are achieved over a wide dynamic range (107<YN<1011) for both D2 (2.45 MeV) and DT (14 MeV) neutrons using a two-channel setup. Instrument characterization and comparison of the timing accuracy with a streak camera-based neutron burn history diagnostic are presented.
Large field double Kirkpatrick–Baez microscope with nonperiodic multilayers for laser plasma imaging
Authors: Bridou F. , Mercier R. , Raynal A. , Clotaire J. Y , Colas C. , Fournet P. , Idir M. , Soullié G. , Remond C. , Troussel P.
Published: October 2002

The double Kirkpatrick–Baez (DBA) microscope is derived from the grazing x-ray Kirkpatrick–Baez (KB) microscope. The KB is compound of two concave spherical mirrors working at grazing incidence and in an energy range about 100 eV–10 keV. The combination of two similar mirrors in the DKB increases the useful field. This device only requires spherical mirrors, more easy to manufacture (precision and roughness) than aspherical ones. In order to image a laser plasma source in a large field of view and within a bandpass of 0.6 keV around 3.4 keV, a KB optic covered with multilayers is developed. In fact, a compromise has to be found between the resolution of the optic (better with a less grazing angle), and the reflectivity (better with more grazing angle). We have chosen to keep the average grazing incidence on the four mirrors around 2°–3° just as for a first uncoated DKB made in our laboratory. This allows us to keep the same radius of curvature for the mirrors. At this energy multilayers are needed, due to the required reflectivity of better than 7% for each mirror. A difficulty appears concerning the energy and angular acceptance of multilayers. It is shown that a nonperiodic multilayer structure can be calculated to solve this problem, in spite of the absorption of the layers at the low energy of our application. The variation of periods is not continuous as in known classical supermirrors, and all the experimental parameters such as complex index of refraction and roughness have to be known. Thicknesses can then be optimized individually. The multilayers were deposited, tested, and the defects identified and corrected. Final experimental results of such stacks are given.
Structure of electric double layers: A self-consistent weighted-density-functional approach
Authors: Patra Chandra N. , Ghosh Swapan K.
Published: October 2002

A self-consistent weighted-density-functional approach is developed for the structure of electric double layer using the restricted primitive model which corresponds to charged hard sphere ions and a continuum solvent. The one-particle correlation function of this inhomogeneous system is evaluated using suitably averaged weighted densities for the short range hard sphere as well as the long range electrical components. The hard-sphere contribution is evaluated by making use of the universality of the density functionals and the correlation function of the uniform hard sphere fluid obtained through the integral equation theory with an accurate closure relation whereas mean spherical approximation is employed for the electrical contribution. Numerical results on the ionic density profile and the mean electrostatic potential near the electrode surface at several surface charge densities are found to show very good agreement with the available simulation results.