bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalencia de las Conductas Alimentarias de Riesgo (CAR) en estudiantes de la Universidad del País Vasco (UPV/EHU)
Authors:   Facultad de Relaciones Laborales y Trabajo Social, Universidad del País Vasco (UPV/EHU), Vitoria-Gasteiz, España, Álvarez Álvaro Karla , Oion Encina Rakel ,   Facultad de Relaciones Laborales y Trabajo Social, Universidad del País Vasco (UPV/EHU), Vitoria-Gasteiz, España, Palacios Navarro Santiago ,   Facultad de Relaciones Laborales y Trabajo Social, Universidad del País Vasco (UPV/EHU), Vitoria-Gasteiz, España
Published: January 2023

Los Trastornos de la Conducta Alimentaria (TCA) son manifestaciones del malestar psicosocial y problemáticas multidimensionales que afectan negativamente a todas las esferas vitales. Las influencias socioculturales hacen que las mujeres jóvenes sean más vulnerables a padecer baja autoestima e insatisfacción corporal y a construir relaciones insanas con la alimentación. La prevalencia del abordaje biomédico ha conllevado que Conductas Alimentarias de Riesgo (CAR), de menor intensidad que los TCA, permanezcan invisibles, siendo su prevención fundamental para la Universidad y el Trabajo Social. El objetivo de esta investigación ha sido estudiar la prevalencia universitaria de Conductas Alimentarias de Riesgo (CAR). Para ello, en mayo de 2021 se utilizó el instrumento Cuestionario Breve de Conductas Alimentarias de Riesgo (CBCAR) en una muestra de 366 estudiantes de la Universidad del País Vasco (UPV/EHU). Así, el 52,19% de esta muestra universitaria no presenta riesgo alguno, mientras que el 24,59% y el 23,22% lo hace de forma moderada o alta respectivamente, observándose una clara asimetría de género respecto a la prevalencia de CAR. En efecto, la preocupación por engordar e insatisfacción corporal tiene una especial incidencia en las disciplinas más feminizadas. Finalmente, el 36,88% señala el ingreso en la universidad como un punto de inflexión en el empeoramiento de su salud biopsicosocial y el 64,75% expresa dificultad para compaginar horarios y rutinas de alimentación saludables.
Detection of Creatinine in Vaginal Secretions of Women with Premature Rupture of Membranes in Third Trimester from Semiurban Population: A Cross-sectional Study
Authors: Deshpande Hemant Gopalrao , Sarkar Monalisa , Shinde Madhukar Jagannath , Gulati Chetan , Joon Shubham
Published: January 2023

Introduction: Spontaneous rupture of the membranes any time beyond the 28th week of pregnancy but before the onset of labour is called Premature Rupture of Membranes (PROM). There are many techniques for diagnosing PROM that is based on both clinical assessments and biological studies. Each of these procedures has benefits and drawbacks. Since foetal urine is the major source of amniotic fluid, the presence of vagina and a high creatinine level may aid in the diagnosis of PROM. Aim: To determine the cut-off levels of serum creatinine in predicting the PROM. Materials and Methods: A cross-sectional study was conducted at Dr. DY Patil Medical College, Hospital and Research Centre in Pune, Maharashtra, India from June 1 2020 to June 5 2021. Two equal groups of 140 each pregnant women with gestational ages ranging from 28-42 weeks were created: one with a history of vaginal leaking (the study group, P), and the other with gestationally matched no leakage (the control group, C). Patient’s details such as age, gestational age, and obstetric history were noted. Each patient was examined and cervicovaginal secretions were collected. A 5 mL of saline was flushed in the posterior fornix of vagina. This fluid with vaginal wash was aspirated and creatinine concentration from vaginal fluid was determined by Jaffee synthetic chemical colorimetric method. The Student’s t-test and the Chi-square test were used to analyse the data. Results: The study group’s vaginal fluid creatinine level was substantially higher (p-value<0.001). The cut-off value of 0.6 mg/dL had highest sensitivity 96.1% and specificity 100%. The area under the Receiver Operating Characteristics (ROC) curve was 0.917. The Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of serum creatinine at cut-off 0.6 mg/dL was 100% and 96.3% respectively. Conclusion: Vaginal fluid creatinine is simple and easily available, which makes it acceptable to the candidate for a diagnosis of PROM.
Intravaginal misoprostol vs. expectant management in premature rupture of membranes with low Bishop scores at term
Authors: Özden S. , Delikara M.N. , Avci A. , Fiçicioglu C.
Published: July 2002

Objectives: To evaluate the efficacy of vaginal misoprostol for cervical ripening and labor induction in premature rupture of membranes (PROM) cases with low Bishop scores at term. Methods: Sixty‐two PROM cases who fulfilled the criteria of 36 weeks of completed gestation, not in active labor, singleton pregnancy with vertex presentation, normal fetal heart rate reactivity, amniotic fluid index >5 cm and Bishop score <5, consented to participate in the study. Thirty‐one of the cases were included in study group and a 50‐μg misoprostol tablet was placed in the posterior vaginal fornix. Another 31 cases were included in control group and managed expectantly. Treatment success was defined as an interval from membrane rupture to delivery of <24 h. Results: The mean admittance–delivery interval was significantly shorter in the study group (8.68±4.40 h) compared with the control group (26.22±18.98 h, P=0.001) and the mean interval from membrane rupture to delivery were also significantly shorter in the study group (19.37±7.20 h) than the control group (33.05±20.85 h, P=0.001). Oxytocin necessity was significantly lower in the study group than the control group (45.2% vs. 100%, P=0.00051). Tachysystole occurred more frequently in the study group (8 cases, 25.8% vs. 2 cases, 6.5%, P=0.038). There were no difference between two groups with regard to birth weights, 1‐ and 5‐min Apgar scores and the need for neonatal intensive care unit. Conclusions: It is effective, safe and economic to use misoprostol vaginally in PROM cases with low Bishop scores at term.
KPRF ideology and its implications for democratization in Russia
Authors: Hashim Syed Mohsin
Published: July 2002

This article looks at the role of the Communist Party of the Russian Federation (KPRF) in Russia's troubled democratization process. The author contends that post-Soviet Russian politics is plagued by a fundamental lack of consensus over regime choice issues. In this polarized setting of zero-sum politics, the KPRF has consolidated its position among anti-regime forces and can negatively impact Russia's transition to markets and democracy.
pH‐Sensitive Hydrogels as Gastrointestinal Tract Absorption Enhancers: Transport Mechanisms of Salmon Calcitonin and Other Model Molecules Using the Caco‐2 Cell Model
Authors: Torres‐Lugo Madeline , García Marcos , Record Rae , Peppas Nicholas A.
Published: July 2002

The main interest of this work was the investigation of the transport mechanisms of salmon calcitonin through the epithelial cell monolayer in the presence and absence of pH‐sensititive hydrogel nanospheres composed of poly(methacrylic acid‐grafted‐poly(ethylene glycol)) (PMAA‐g‐EG). For this purpose, a gastrointestinal cell culture model, the Caco‐2 cell line, was employed. The transport of other macromolecules such as fluorescein sodium, fluorescein isothiocyanate dextran, and 14C‐mannitol were also investigated and compared. Transport experiments were conducted in the apical‐to‐basolateral direction at 37 and 5 °C and from the basolateral‐to‐apical direction at 37 °C. Results revealed that the presence of P(MAA‐g‐EG) nanospheres increased the transport of paracellularly transported molecules such as 14C‐mannitol and fluorescein isothiocyanate dextran when compared to controls. Fluorescein sodium salt solutions were investigated as an actively transported molecule. The transport of fluorescein was affected by the concentration of PEG chains in the structure. Salmon calcitonin transport was enhanced in the presence of the nanospheres. The comparison of the transport behavior of dextran and calcitonin revealed that the main transport mechanism for salmon calcitonin through epithelial cell monolayers is predominantly paracellular.
In situ characterization of a NO‐sensitive peroxidase in the lignifying xylem of Zinnia elegans
Authors: Barceló A. Ros , Pomar Federico , Ferrer María A. , Martínez Pilar , Ballesta Maria C. , Pedreño María A.
Published: July 2002

The lignifying xylem from Zinnia elegans stems gives an intense reaction with 3,3′,5,5′‐tetramethylbenzidine (TMB), a reagent previously reported to be specific for peroxidase/H2O2. However, the staining of lignifying xylem cells with TMB is apparently the result of two independent mechanisms: one, the catalase‐sensitive (H2O2‐dependent) peroxidase‐mediated oxidation of TMB, and the other, the catalase‐insensitive oxidation of TMB, probably mediated by xylem oxidases which are specific from lignifying tissues. The catalase‐insensitive oxidation of TMB by the Z. elegans xylem was sensitive to sodium nitroprusside (SNP), a nitric oxide (NO)‐releasing compound that, when used at 5.0 mM, is capable of sustaining NO concentrations of 6.1 µM in the aqueous phase. This effect of SNP was totally reversed by 150 µM 2‐phenyl‐4,4,5,5‐tetramethyl imidazoline‐1‐oxyl‐3‐oxide (PTIO), an efficient NO scavenger in biological systems, so the above‐mentioned effect must be ascribed to NO, and not to other nitrogen oxides. This response of the catalase‐insensitive TMB‐oxidase activity of the lignifying Z. elegans xylem was similar to that shown by a basic peroxidase isolated from the intercellular washing fluid, which showed TMB‐oxidase activity, and which was also inhibited by 5 mM SNP, the effect of SNP also being reversed by 150 µM PTIO. These results suggest that peroxidase was the enzyme responsible for the NO‐sensitive catalase‐insensitive TMB‐oxidase activity of the lignifying Z. elegans xylem. Further support for this statement was obtained from competitive inhibitor‐dissected histochemistry, which showed that this stain responded to peroxidase‐selective competitive inhibitors, such as ferulic acid and ferrocyanide, in a similar way to the Z. elegans basic peroxidase. From these results, we conclude that this NO‐sensitive catalase‐insensitive oxidation of TMB is apparently performed by the Z. elegans basic peroxidase, and that the regulation of this enzyme by NO may constitute an intrinsically programmed event during the differentiation and death of the xylem.
Expression of asparagine synthetase in rice (Oryza sativa) roots in response to nitrogen
Authors: Kawachi Tahei , Sueyoshi Kuni , Nakajima Ayumi , Yamagata Hiroshi , Sugimoto Toshio , Oji Yoshikiyo
Published: July 2002

The expression of asparagine synthetase (AS; EC 6.3.5.4) in response to externally supplied nitrogen was investigated with respect to enzyme activity and protein levels as detected immunologically in rice (Oryza sativa) seedlings. The asparagine content was very low in leaves and roots of nitrogen‐starved rice plants but increased significantly after the supply of 1 mM NH4+ to the nutrient solution. While neither AS activity nor AS protein could be detected in leaves and roots prior to the supply of nitrogen, levels became detectable in roots but not in leaves within 12 h of the supply of 1 mM NH4+ or 10 mM glutamine. Other nitrogen compounds, such as nitrate, glutamate, aspartate and asparagine had no effect. Methionine sulfoximine completely inhibited the NH4+‐induced accumulation of AS protein but did not affect the glutamine‐induced accumulation of the enzyme. The results suggested that glutamine or glutamine‐derived metabolites regulate AS expression in rice roots.
TcGPXII, a glutathione-dependent Trypanosoma cruzi peroxidase with substrate specificity restricted to fatty acid and phospholipid hydroperoxides, is localized to the endoplasmic reticulum
Authors: WILKINSON Shane R. , TAYLOR Martin C. , TOUITHA Said , MAURICIO Isabel L. , MEYER David J. , KELLY John M.
Published: July 2002

Until recently, it had been thought that trypanosomes lack glutathione peroxidase activity. Here we report the subcellular localization and biochemical properties of a second glutathione-dependent peroxidase from Trypanosoma cruzi (TcGPXII). TcGPXII is a single-copy gene which encodes a 16kDa protein that appears to be specifically dependent on glutathione as the source of reducing equivalents. Recombinant TcGPXII was purified and shown to have peroxidase activity towards a narrow substrate range, restricted to hydroperoxides of fatty acids and phospholipids. Analysis of the pathway revealed that TcGPXII activity could be readily saturated by glutathione and that the peroxidase functioned by a Ping Pong mechanism. Enzyme reduction was shown to be the rate-limiting step in this pathway. Using immunofluorescence, TcGPXII was shown to co-localize with a homologue of immunoglobulin heavy-chain binding protein (BiP), a protein restricted to the endoplasmic reticulum and Golgi. As the smooth endoplasmic reticulum is the site of phospholipid and fatty acid biosynthesis, this suggests that TcGPXII may play a specific role in the T. cruzi oxidative defence system by protecting newly synthesized lipids from peroxidation.
T‐Cell Repertoire Analysis in Acute and Chronic Human Chagas'Disease: Differentail Frequencies of Vb5 Expressing T Cells
Authors: Costa R. P. , Gollob K. J. , Fonseca L. L. , Rocha M. O. C. , Chaves A. C. L. , Medrano‐Mercado N. , Araújo‐Jorge T. C. , Antas P. R. Z. , Correa‐Oliveira R. , Gazzinelli G. , Carvalho‐Parra J. , Dutra W. O.
Published: July 2002

Here, we analysed the use of Vb‐TCR regions by CD4? and CD8? T cells from acute and chronic chagasic patients using ¯ow cytometry. We determined the Vb expression in cells freshly isolated from patients, as well as after in vitro stimulation with antigens derived from epimastigote (EPI) or trypomastigote (TRYPO) forms of Trypanosoma cruzi. Analysis of Vb‐TCR expression of T cells freshly isolated from patients showed a decrease in Vb5 expression in the CD4? T‐cell population from acutely infected individuals, whereas CD4?Vb5? T cells were found to be increased in chronic patients with the cardiac, but not indeterminate, clinical form. After culturing peripheral blood mononuclear cells (PBMC) from chronic patients with EPI or TRYPO, we found that both antigenic preparations led to a preferential expansion of CD4?Vb5? T cells. EPI stimulation also led to the expansion of CD8?Vb5? T cells, whereas TRYPO led to the expansion of this cell population only if PBMC were from cardiac and not indeterminate patients. We observed that TRYPO stimulation led to an increase in the frequency of CD4?Vb17? T cells in cultures of PBMC from indeterminate patients, whereas an increase in the frequency of CD8?Vb17? T cells was found upon TRYPO stimulation of PBMC from cardiac patients. Despite this increase in the frequency of Vb17? T‐cell populations upon TRYPO stimulation, the same antigenic preparation led to a much higher expansion of Vb5? T cells. These results show a differential expression of Vb5‐TCR in cells freshly isolated from chagasic patients in different stages of the disease and that parasite‐speci®c antigens stimulate a portion of the T‐cell repertoire with preferential usage of Vb5‐TCR.
The IVOG® feeding station: a tool for monitoring the individual feed intake of group‐housed weanling pigs
Authors: Bruininx E. M. A. M. , Van Der Peet‐Schwering C. M. C. , Schrama J. W. , Den Hartog L. A. , Everts H. , Beynen A. C.
Published: July 2002

Three batches of weanling pigs (total n=310 pigs) were used in a 34‐day experiment to validate the use of an IVOG® feeding station as a tool for monitoring individual feed intake of group‐housed weanling pigs. An IVOG® feeding station for weanling pigs consists of a single‐space dry feeder placed on a load cell in combination with electronic identification. Data of 192 weanling pigs (18 pens) fed by IVOG® feeding stations were used to develop a protocol for the screening of IVOG® data. To assess the quality of the IVOG® data, the feed intake per pen computed from the screened IVOG® data was compared with the feed intake calculated from feed weighing. To assess the suitability of the use of IVOG® feeding stations under practical pig husbandry conditions, performance of 96 weanling pigs fed by the IVOG® feeding stations was compared with that of 118 weanling pigs that were fed using commercial single‐space dry feeders (11 pens). Feed intake per pen computed from the IVOG® data was similar to the feed intake calculated from feed weighing (average recovery 101.1%) for all test periods (p > 0.1). Furthermore, feed recovery did not differ among feeding stations (p > 0.1). During the first 13 days after weaning, the average daily feed intake (ADFI) of weanling pigs fed by the single‐space dry feeders was higher (p < 0.05) than that of weanling pigs fed by the feeding stations. Average daily gain and gain to feed ratios did not differ (p > 0.1) between both feeding systems. During the remaining 21 days and averaged over the entire experimental period, performance did not differ between the feeding systems (p > 0.1). It can be concluded that IVOG® feeding stations for weanling pigs are a suitable tool to monitor individual feed intake of group‐housed weanling pigs.
TRANSHIATAL VERSUS IVOR‐LEWIS OESOPHAGECTOMY: IS THERE A DIFFERENCE?
Authors: Rindani Rahul , Martin Christopher J. , Cox Michael R.
Published: July 2002

Introduction: Curative oesophageal resection for carcinoma may be carried out by either the transhiatal or the Ivor‐Lewis transthoracic technique. The aims of this study were to compare the morbidity, 30‐day mortality and long‐term survival of the two techniques in the treatment of oesophageal carcinoma and to provide data to calculate the sample sizes for a prospective randomized trial.

Methods: Results from 44 series published between January 1986 and December 1996 were reviewed. Thirty‐three papers reported results on 2675 patients having transhiatal (THO) and 29 papers reported results on 2808 patients having Ivor‐Lewis oesophagectomy (ILO).

Results: The two groups were comparable in terms of age, sex and stage of the disease. There was no apparent difference in postoperative morbidity between the two groups with respect to respiratory complications (24% for THO, 25% for ILO), cardiovascular complications (12.4% for THO, 10.5% for ILO), wound infection (8.8% for THO, 6.2% for ILO) and chylothorax (2.1% for THO, 3.4% for ILO). The transhiatal group appeared to have a higher incidence of anastomotic leaks (16% for THO, 10% for ILO), anastomotic strictures (28% for THO, 16% for ILO) and recurrent laryngeal nerve injuries (11.2% for THO, 4.8% for ILO). The 30‐day mortality was 6.3% for transhiatal and 9.5% for Ivor‐Lewis oesophagectomy. Overall long‐term survival at 5 years was similar (24% for THO, 26% for ILO).

Conclusions: The surgical approach to oesophagectomy was not an important determinant of morbidity and long‐term survival in patients with oesophageal carcinoma. Transhiatal oesophagectomy was associated with a higher incidence of anastomotic complications and recurrent laryngeal nerve injury. Ivor‐Lewis oesophagectomy had a higher mortality. In order to demonstrate a significant difference in morbidity or long‐term survival between the two techniques 3100 patients would be required in each arm of a prospective randomized trial.
THOMAS PEEL DUNHILL: PIONEER THYROID SURGEON
Authors: Vellar IVO D.
Published: July 2002

Thomas Peel Dunhill, a name by now almost completely forgotten in his native Australia, was born in 1876 near Kerang in the State of Victoria. Although he qualified as a pharmacist in 1898, Dunhill had already decided to study medicine and graduated in 1903 from the Clinical School of the Melbourne Hospital. He was regarded as an outstanding student. In 1905 Dunhill was invited to join the Senior Medical Staff at St Vincent’s Hospital by Mother Berchmans Daly, the then Mother Rectress. In 1906 Dunhill was awarded the MD and in 1907 he performed his first thyroid lobectomy under local anaesthesia for toxic goitre. As early as 1908, Dunhill under‐ stood the essentials for successful surgery in thyrotoxicosis—enough thyroid had to be removed to cure the condition. To this end, he advocated a bilateral attack on the thyroid and advocated thyroidectomy in the thyrocardiac patient. He did this before Theodor Kocher, Charles Mayo, William Halsted or George Crile. In 1911 Dunhill visited the USA and England and communicated his results to the thyroid surgeons in both countries (230 cases of exophthalmic goitre operated on with four deaths). The English could not, or would not, believe his results as the mortality of surgery for exophthalmic goitre at St Thomas’s Hospital, London in 1910 was 33%. Dunhill served with distinction in the Great War and his abilities favourably impressed George Gask, who was to become the Professor of Surgery at St Bartholomew’s Hospital, London. Gask eventually invited Dunhill to join his Unit and Dunhill left St Vincent’s Hospital in 1920. Between 1920 and Dunhill’s retirement at the age of 60 in 1935, he became the outstanding general surgeon at St Bartholomew’s Hospital. Dunhill and Cecil Joll, were regarded as the leading thyroid surgeons in the UK. Knighted in 1933, Dunhill was appointed surgeon to the Royal Household, serving four British monarchs. In addition to his brilliant surgical career, Dunhill maintained a love for the land. He was an expert fly fisherman. Dunhill retired from surgical practice in 1949 and died at the age of 80 in 1957 at his London home. Many eulogies were delivered, especially by Sir James Paterson Ross and Sir Geoffrey Keynes, his former pupils. Dunhill’s exploits as a thyroid surgeon in the development of a safe and effective treatment for thyrotoxicosis and in operating on the thyrocardiac enables this modest, courteous and loyal Australian to be included with Theodor Kocher, Charles Mayo, William Halsted and George Crile in the pantheon of pioneer thyroid surgeons.
Lung function outcome in children of premature birth
Authors: Kennedy JD
Published: July 2002

Abstract: Since the 1960s there has been a continual improvement in the survival of premature infants of birthweight less than 1500 g. This has resulted in an increase in the prevalence of bronchopulmonary dysplasia (BPD), or its milder form, chronic lung disease (CLD) of prematurity. In children with BPD, the initial air trapping improves in the first 3–4 years of life, but small airway obstruction is often slow to improve, suggesting dysanaptic lung growth. Despite this, the majority of older children and adolescents with BPD/CLD do not have significant respiratory symptoms. Children born prematurely with or without hyaline membrane disease may also have a reduction in expiratory flows during childhood, albeit less severe. The clinical significance of this in the longer term is unclear. Although significant associations between decrements in expiratory flows, neonatal oxygen therapy and assisted ventilation have been demonstrated. Airway function has also been reported to be largely unrelated with perinatal events but strongly associated with birthweight. The latter suggests that intra‐uterine factors such as under‐nutrition may be more important than hitherto recognized. Because of a lack of longitudinal studies, it is unclear how lung function will track during adolescence and adult life. Bronchial hyper‐responsiveness is significantly increased in children with BPD and to a lesser extent in those born prematurely with or without hyaline membrane disease. It is unclear whether this is due to a genetic predisposition, neonatal lung injury or anatomically smaller airways. Given the morbidity and fiscal cost of a premature birth, effective strategies to reduce the premature birth rate are needed.
Urological problems in conjoined twins
Authors: Wilcox  , Quinn  , Spitz  , Kiely  , Ransley
Published: July 2002

Objectives

 To review the urological abnormalities in conjoined twins, a rare congenital abnormality arising from an incomplete separation of a pair of monozygotic twins, and who can be joined from the head to the pelvis with varying degrees of union.

Patients and methods

 The records and urological anomalies of conjoined twins presenting from 1985 to 1995 were reviewed retrospectively and the management and surgical reconstruction described.

Results

 Seven of 11 sets of conjoined twins underwent surgical exploration. Complex urological problems occurred in all twins with omphalo‐ischiopagus. The urological anomalies were: Set 1; both twins had one lateral crossed fused renal ectopia with uncrossed ureters draining into a single bladder with one urethra. They had one set of genitalia. Each twin received one crossed fused ectopic kidney, half the bladder and genitalia, with one retaining the urethra and one a vesicostomy. Set 2; these twins had four kidneys (two lateral and two central that were fused), four ureters (two of which crossed) and these drained into two sagittal bladders that emptied by one urethra associated with a single set of external genitalia containing three corpora cavernosa. At separation, the crossed ureters were re‐routed, each received a bladder and the genitalia were split. Set 3; there were four kidneys with two crossed ureters draining into two collateral bladders, there was a partial duplication of the urethra and a single hypospadiac penis. After separation, each had kidneys draining into a bladder, one received the urethra and external genitalia, and one a urostomy.

Conclusion

 Complex urological problems occur in conjoined twins, although restricted to those with pelvic fusion (ischiopagus). Assessment and treatment needs to be individualised and overseen by a surgeon with experience in complex urology.
Fatal emphysematous pyelonephritis with gas in the spinal extradural space in a patient with diabetes
Authors: Sailesh S. , Randeva H. S. , Hillhouse E. W. , Patel V.
Published: July 2002

SUMMARY

Background  Emphysematous pyelonephritis (EP) is a rare but life‐threatening condition of the upper urinary tract, characterized by the presence of gas in the renal parenchyma and perirenal space. The vast majority of patients with EP (90%) are known to have diabetes, with Escherichia coli being the most common causative pathogen.

Case report  We present a case of fatal bilateral EP in a patient with diabetes, with an unusual radiological finding of gas around the spinal cord and in the psoas muscle, with renal parenchymal sparing. Our case serves as an important reminder of this life threatening entity in diabetic patients, which is not well recognized by clinicians because of its rarity.
Cervical incompetence: the use of transvaginal sonography to provide an objective diagnosis
Authors: Macdonald R. , Smith P. , Vyas S.
Published: July 2002

Objective

To investigate the use of transvaginal sonography in monitoring the cervix in women at high risk of a preterm delivery.

Study design

One hundred and six women at high risk of preterm labor had regular cervical monitoring by transvaginal ultrasound throughout pregnancy from the second trimester to delivery. The study was designed to be observational, but intervention was considered if the cervical length fell below 10 mm.

Results

Eleven women demonstrated opening of the cervical canal at rest or with fundal pressure before 24 weeks' gestation. Between 2 and 17 days later all 11 cervices progressively shortened to a cervical length of < 10 mm. Nine women had a cervical cerclage. Seven women had fetal membranes visible within the cervical canal at the time of cerclage. One woman miscarried at 18 weeks, and the other 10 had live births at a median gestational age of 36 (range, 27–38) weeks.

Conclusions

Cervical length shortening in the second trimester, once started, progressed to a cervical length under 10 mm. Opening of the cervical os at rest or in response to fundal pressure detected by transvaginal ultrasound appears to be the early ultrasound feature of cervical incompetence. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Lipoprotein(a) Serum Levels and Vascular Diseases in an Older Caucasian Population Cohort
Authors: Pantoni Leonardo , Sarti Cristina , Pracucci Giovanni , Di Carlo Antonio , Vanni Paola , Inzitari Domenico , For The Italian Longitudinal Study on Aging
Published: July 2002

OBJECTIVE: To investigate elevated lipoprotein(a) [Lp(a)] levels as a risk factor for stroke, myocardial infarction, angina, intermittent claudication, and combination of the above in a cohort of unselected older individuals.

DESIGN: Population cohort from one of the eight centers participating in the Italian Longitudinal Study on Aging (ILSA).

SETTING: General community.

PARTICIPANTS: A subsample of 446 subjects (M/F: 231/215, mean age: 74.5 ± 5.7 years) of the original, randomly selected, population cohort of 704 individuals, 65 to 84 years of age, free‐living or institutionalized in the Impruneta Municipality, area of Florence, Italy.

MEASUREMENTS: Conventional vascular risk factors and vascular diseases defined following a two‐step procedure (screening phase and confirmation on positives) using standard and validated criteria. Lp(a) levels determined by an ELISA method.

RESULTS: No association was observed between elevated Lp(a) levels alone and any of the examined vascular diseases (stroke, myocardial infarction, angina, and intermittent claudication). In contrast, examining the interactions between elevated Lp(a) and conventional vascular risk factors, when elevated Lp(a) was combined with a history of smoking, a marked increase in the risk of vascular diseases combined (odds ratio [OR]: 4.12; 95% confidence interval [CI]: 1.27–13.40) was observed, much higher than that expected based on the additive effect of smoking and elevated Lp(a) alone.

CONCLUSIONS: With the cautions due to the cross‐sectional design of the study and the limited statistical power, these results suggest a possible synergistic effect between elevated Lp(a) levels and other pro‐atherogenic factors such as smoking on the risk of vascular diseases in older individuals.
Pressure dependence of the D
X center in Ga1−xAlxAs:Te in the vicinity of the Γ-X crossover
Authors: Li M. F. , Shan W. , Yu P. Y. , Hansen W. L. , Weber E. R. , Bauser E.
Published: July 2002

The pressure dependence of the DX center in Ga1−xAlxAs :Te has been studied in two samples with x=0.15 and 0.35, respectively. The pressure coefficients of the activation energies for both emission and capture were found to change sign when the band gap of GaAlAs changes from direct to indirect. These results, together with previous experiments, suggested that electrons can be emitted from and capture into the DX centers via both L and X valleys.
I
n s
i
t
u study of p-type amorphous silicon growth from B2H6:SiH4 mixtures: Surface reactivity and interface effects
Authors: Collins R. W.
Published: July 2002

I n situ ellipsometry provides monolayer sensitivity to the reaction of B2H6:SiH4 doping gas mixtures with p- and i-type plasma-enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) surfaces at 180 and 250 °C. This low-temperature reaction, leading to the slow growth (1–3 Å/min) of a-Si:H:B by CVD (without plasma excitation), requires a clean a-Si:H surface and both B2H6 and SiH4 in the doping gas. We suggest that the high B content of CVD a-Si:H:B at p-i and i-p interfaces and on the film-coated regions of single-chamber reactors, may contribute to poor interface characteristics and residual contamination in devices.
High-power nonplanar quantum well heterostructure periodic laser arrays
Authors: Givens M. E. , Zmudzinski C. A. , Bryan R. P. , Coleman J. J.
Published: July 2002

Optical pulsed powers of 8 W from a single uncoated facet and low (<200 A/cm2) threshold current densities have been obtained from 3.1-mm-wide (cavity length=483 μm) nonplanar periodic quantum well heterostructure laser diode arrays grown by metalorganic chemical vapor deposition over a selectively etched corrugated substrate. The resulting nonplanar lateral active layer profile provides index guiding and suppresses lateral lasing regardless of device width.
γ-ray enhanced quenching phenomenon of photoconductance in undoped and In-doped semi-insulating GaAs
Authors: Kuriyama K. , Kawahara H. , Satoh M. , Kawakubo T.
Published: July 2002

In undoped and In-doped semi-insulating GaAs with various dislocation densities, we have found that the quenching phenomenon of photoconductance is enhanced by γ irradiation above 107 rad at room temperature. In particular, this effect is obvious for crystals with dislocation densities of 10–103/cm2. The new stage induced by γ irradiation is found around 100 K and disappears gradually by annealing above 300 °C. The time dependence of photoconductance suggests the existence of the newly introduced state assisting the transition from a normal midgap electron trap (EL20) to a metastable state (EL2*) in the semi-insulating materials.
Boron surface segregation in silicon molecular beam epitaxy
Authors: de Frésart E. , Wang K. L. , Rhee S. S.
Published: July 2002

Boron surface segregation in Si molecular beam epitaxy has been measured on Si(111) substrate as a function of the growth temperature (400 °C≤Ts≤900 °C) by Auger electron spectroscopy. Boron oxide (B2O3) was used as dopant material to achieve a boron concentration level of about 1×1019 cm−3. Three temperature regions are observed for the behavior of the ratio rd=Is/Ib of the surface (Is) to the bulk (Ib) dopant atomic fractions. At low temperature, Ts=400–570 °C the ratio maintains at the value rd≂1.5. For 570 °C≤Ts≤720 °C, rd increases to a plateau rd≂5.5, and then jumps to rd=42 in the 720–750 °C region. At higher temperature, Ts≥750 °C, rd decreases according to a relation which can be approximated by the classical equilibrium segregation theory. In that region, the boron Gibbs free energy of surface segregation is calculated from data to be ΔGS=−0.33±0.02 eV. Evolution of rd is closely correlated to the etch pit count and electron channeling results revealing amorphous, polycrystalline, and epitaxial growth, when going from low to high growth temperature.
Photoluminescence and the band structure of InAsSb strained-layer superlattices
Authors: Kurtz S. R. , Osbourn G. C. , Biefeld R. M. , Lee S. R.
Published: July 2002

Infrared photoluminescence measurements were performed on InAs0.13Sb0.87 /InSb strained-layer superlattices. In thick layered structures we observed very low energy transitions proving that a type II superlattice occurs in the InAsSb system. Band structures were calculated based on estimates of the band offsets and strain shifts obtained from the photoluminescence data.
Diamond-like carbon films prepared with a laser ion source
Authors: Wagal S. S. , Juengerman E. M. , Collins C. B.
Published: July 2002

Diamond-like carbon films have been deposited onto clean, unseeded substrates using a hybrid ion beam technique. In this method the ion fluences available for acceleration were particularly enhanced by the use of laser ablation plumes ejected from highly purified graphite targets. The combination of levels of purity characteristic of ultrahigh vacuum environments, large ratios of ion to neutral concentrations, and high fluences showed considerable merit for the growth of large-area (10 cm2 ) films of optical quality and uniformity at deposition rates approaching 20 μm/h.
Monolithic integration of a short-length GaInAs photoconductor with a GaAs/GaAlAs optical waveguide on a GaAs semi-insulating substrate
Authors: Mallecot F. , Vinchant J. F. , Razeghi M. , Vandermoere D. , Vilcot J. P. , Decoster D.
Published: July 2002

We report the first fabrication of a Ga0.47In0.53As planar photoconductive detector, associated with a GaAs/GaAlAs rib waveguide grown on a semi-insulating GaAs substrate, which needs a short-length absorbing layer to detect the optical signal. Because of the GaAlAs epilayer, a GaInAs length of about 100 μm only is needed to detect 90% of the optical signal, accordingly to results predicted using a four-layer model with complex refractive indices in each layer.
Ambipolar diffusion length measurements on hydrogenated amorphous silicon p-i-n structures
Authors: Balberg I. , Delahoy A. E. , Weakliem H. A.
Published: July 2002

The determination of the ambipolar diffusion length within the i layer of a p-i-n structure made of hydrogenated amorphous silicon is reported for the first time. It is shown that this important parameter can be determined by measurements carried out on the entire structure. One finds for a typical cell structure that the measured diffusion length is 10–20% smaller than the true i-layer value.
Electron diffusion length in rapid thermal processed p-type silicon
Authors: Quat Vu Thuong , Eichhammer W. , Siffert P.
Published: July 2002

Electron diffusion length in p-type virgin silicon has been measured by the surface photovoltage method after rapid thermal processing as a function of process time duration and process temperature. The results obtained are consistent with a model involving defects acting as a single dominant recombination center induced in the bulk. This recombination center is responsible for the severe degradation of the diffusion length, even at process temperatures as low as 600 °C. An activation energy of 1.48±0.28 eV is found for the center introduction rate. The work shows that the diffusion length measurement is a very sensitive tool in the study of rapid thermal process induced recombination centers in the bulk, with direct correlation to device performance.
Pt-coated substrate effect on oxide superconductive films in low-temperature processing
Authors: Hatta S. , Higashino H. , Hirochi K. , Adachi H. , Wasa K.
Published: July 2002

Excellent films of a high Tc oxide superconductor were easily produced on Pt-coated substrates at 650 °C. The film superconductivity was significantly improved by the Pt buffer layer. The c axis of the superconductive film was preferentially oriented perpendicularly to the plane with the crystalline oriented Pt coating layer.
Analysis of ytterbium arsenide films grown on GaAs by molecular beam epitaxy
Authors: Richter H. J. , Smith R. S. , Herres N. , Seelmann-Eggebert M. , Wennekers P.
Published: July 2002

X-ray photoelectron spectroscopy has been used to investigate thin single-crystal films of ytterbium arsenide grown epitaxially on GaAs by molecular beam epitaxy. Sputter profiles indicate the absence of oxide impurities and the presence of only trivalent ytterbium, which means that the epitaxial film is composed entirely of YbAs. X-ray diffraction analysis revealed a moderate imperfection of the crystalline quality of the YbAs and a lattice misfit of about 8×10−3 with respect to GaAs.
Defect-related Si diffusion in GaAs on Si
Authors: Freundlich A. , Leycuras A. , Grenet J. C. , Grattepain C.
Published: July 2002

Preferential diffusion channels of silicon are evidenced in GaAs grown by metalorganic vapor phase epitaxy on Si(100). The density of these diffusion channels is found to be consistent with the measured dislocation density. In addition, combining scanning electron microscopy and x-ray fluorescence it is shown that a large amount of Si emerges at the surface inside small 〈011〉 overgrowth oriented defects (≊1 μm) present at the GaAs/Si surface.
High-purity epitaxial indium phosphide grown by the hydride technique
Authors: McCollum M. J. , Kim M. H. , Bose S. S. , Lee B. , Stillman G. E.
Published: July 2002

Indium phosphide layers with electron mobilities at liquid-nitrogen temperature of 91 000–125 000 cm2 /V s and carrier concentrations of 3–6×1014 cm−3 have been routinely grown by hydride vapor phase epitaxy. This 77 K mobility is significantly higher than the best previously reported for hydride vapor phase epitaxial InP. Analysis by variable temperature Hall effect, photothermal ionization spectroscopy, photoluminescence, and magnetophotoluminescence confirms the high purity of the samples. The influence of O2 on Si incorporation (injected over the In source) has also been studied. The injected oxygen did not significantly influence the silicon donor concentration.
Stability of TaSix-GaAs Schottky barriers in rapid thermal processing
Authors: Haynes T. E. , Chu W. K. , Han C. C. , Lau S. S. , Picraux S. T.
Published: July 2002

n-type GaAs samples coated with TaSi2 and Ta5 Si3 Schottky barrier contacts were heated in a flashlamp rapid thermal processing (RTP) system to temperatures between 600 and 950 °C. We have measured the evaporation of gallium and arsenic through the contact overlayers which results from the decomposition of the GaAs substrate. These decomposition measurements have been correlated with the Schottky barrier behavior as determined from forward-bias current-voltage characteristics and selected capacitance-voltage measurements. The high-temperature stability against decomposition and electrical degradation was superior for Ta5 Si3 contacts relative to TaSi2 contacts. We observed for both contact compositions that the onset temperature for decomposition of GaAs was slightly lower than the maximum temperature for electrical stability. Thus, we found that in some cases substantial decomposition occurred with no effect on the current-voltage characteristics. For example, Ta5 Si3 contacts maintained a stable barrier height of 0.78 eV through 10 s RTP treatments up to 900 °C, in spite of decomposition of at least ten equivalent monolayers of GaAs.
Enhanced resistance to photorefraction and photovoltaic effect in Li-rich LiNbO3:Mg crystals
Authors: Wen Jin-ke , Wang Liang , Tang Yan-sheng , Wang Hua-fu
Published: July 2002

We have found that in connection with photorefraction the Li-rich LiNbo3:Mg (5 mol %) can withstand higher light intensities than the congruent LiNbO3:Mg (5 mol %) and that the improvement is due to the increased photoconductivity with little change in photovoltaic current.
Precipitation of group V elements and Ge in SiO2 and their drift in a temperature gradient
Authors: Celler G. K. , Trimble L. E. , Sheng T. T. , Kosinski S. G. , West K. W.
Published: July 2002

It is shown that P, Sb, and Ge ions implanted in SiO2 precipitate into spherical clusters of up to 1000 Å diameter when heat treated in an oxygen-free ambient. This behavior is similar to that reported earlier for As implants. The clusters can be detected directly by transmission electron microscopy, or inferred from the unidirectional drift of the doped zone in a temperature gradient. Boron, a representative of group III, is the only element among those tested that does not migrate in a ∇T, suggesting the absence of phase separation.
Analytical description for the diffusion and recombination of point defects in silicon
Authors: Cowern N. E. B.
Published: July 2002

A simplified analysis is given of point-defect diffusion in the presence of traps which saturate on recombination. Examples of this phenomenon are self-interstitial diffusion and gettering in Czochralski silicon, and coupled interstitial-vacancy diffusion in perfect crystalline silicon. When recombination is diffusion limited, a simple diffusion equation is obtained, with an effective diffusivity D̃ which is an analytical function of the point-defect and trap concentrations. The physical meaning of this function is described.
Photosensitivity of the 714 and 730 cm−1 absorption bands in semi-insulating GaAs: Evidence for a deep donor involving oxygen
Authors: Alt H. Ch.
Published: July 2002

The optically induced metastable interconversion processes of the oxygen-related vibrational modes at 730 and 714 cm−1, bands A and B, have been studied and compared with related properties of the EL2 defect. It is shown that the conversion from A to B is due to a charge exchange with the neutral EL2 level. The reverse process, recovery of band A, is observed after quenching of EL2. Conclusive evidence is presented that the two bands are associated with a donor in the upper half of the band gap. From Hall effect measurements, a trap energy of 0.43 eV below the conduction band is expected. A preliminary calibration of the absorption strength yields defect concentrations of ≊1015 cm−3 in some samples.
Disorder-defined buried-heterostructure AlxGa1−xAs-GaAs quantum well lasers by diffusion of silicon and oxygen from Al-reduced SiO2
Authors: Guido L. J. , Major J. S. , Baker J. E. , Holonyak N. , Burnham R. D.
Published: July 2002

We describe a convenient method utilizing chemical reduction of SiO2 by Al (from AlxGa1−xAs) to generate Si and O for impurity-induced layer disordering (IILD) of AlxGa1−xAs-GaAs quantum well heterostructures (QWHs). Experimental data show that Si-O diffusion (from SiO2) is an effective source of Si for Si-IILD and of O that compensates the Si donor, thus resulting in higher resistivity layer-disordered crystal. The usefulness of the Si-O IILD source for fabricating low-threshold disorder-defined buried-heterostructure AlxGa1−xAs-GaAs QWH lasers is demonstrated.
Novel GaAs voltage-controllable negative differential resistance transistor prepared by molecular beam epitaxy
Authors: Yarn K. F. , Wang Y. H. , Chang C. Y.
Published: July 2002

A three-terminal n+-i-δp+-i-n+ bipolar–unipolar transition transistor has been successfully fabricated by molecular beam epitaxy. Due to the combination of the two transitions, they make a genuine N-shaped current-voltage characteristic. It is a voltage-controlled device with a variable peak-to-valley current ratio which is adjustable by a bias applied to the third terminal (base). A hypothetical model is proposed and confirmed by experiments.
Electrostatically defined heterojunction rings and the Aharonov–Bohm effect
Authors: Ford C. J. B. , Thornton T. J. , Newbury R. , Pepper M. , Ahmed H. , Peacock D. C. , Ritchie D. A. , Frost J. E. F. , Jones G. A. C.
Published: July 2002

Micron-sized loops of high-mobility two-dimensional electron gas have been made on GaAs-AlGaAs heterostructures using a novel split-gate technique. Aharonov–Bohm oscillations of amplitude up to 20% of the device resistance have been observed at very low temperatures (T<100 mK), together with h/2e oscillations which appear to be due to interference between pairs of time-reversed paths near B=0. The h/e period is found to vary by ∼25% with magnetic field, possibly as a result of the formation of edge states. In the quantum Hall effect, plateaus in Rxx are seen at high B due to variations in carrier concentration across the ring, which may cause backscattering of some edge states.
Lateral forces and topography using scanning tunneling microscopy with optical sensing of the tip position
Authors: Taubenblatt Marc A.
Published: July 2002

A technique is described for measurement of lateral forces on a scanning tunneling microscopy (STM) tip simultaneously with surface topography, using optical sensing of the STM tip vibration. The STM tip is caused to vibrate near a resonant mode in the lateral direction, using the capacitive forces between the tip and the surface under study. Topography is monitored using the z-displacement feedback voltage, in a low-frequency loop, while optical sensing of the high-frequency tip vibration amplitude monitors lateral forces acting on the tip.
Current-voltage and capacitance-voltage behavior of high-resistivity (AlxGa1−x)yIn1−yP on GaAs
Authors: Casey H. C. , McCalmont J. S. , Pandharpurkar H. , Wang T. Y. , Stringfellow G. B.
Published: July 2002

Unintentionally doped layers of (AlxGa1−x)y In1−y P with energy gaps of approximately 2.0 eV were grown lattice matched to GaAs by organometallic vapor phase epitaxy. These layers were high resistivity. Current-voltage (I-V) and capacitance-voltage (C-V) measurements were made on Cr/Au (AlxGa1−x)y In1−y P-GaAs metal-insulator-semiconductor capacitors. These measurements gave a ln I variation with V1/2 as observed for insulators such as Si3N4 on Si. This conduction behavior is characteristic of the Frenkel–Poole effect which is the electric field enhanced thermal excitation of trapped electrons into the conduction band. The C-V measurements were similar to the small hysteresis behavior of high-resistivity oxygen-doped AlxGa1−xAs on GaAs.