bluuebunny/crossref_metadata_2025 huggingface dataset:
The testing of clinical skills in dietetic students prior to entering clinical placement
Authors: Pender F. T. , de Looy A. E.
Published: January 2004

Background  One of the most important requirements for contemporary education of a health care professional is to develop a framework for theory and practise which results in attainment of professional competencies suitably robust for a lifetime of practise (Howe, 2002). In the context of those educating preregistration dietitians, this offers the challenge of presenting the student with innovative curricula designed to deliver the appropriate level of knowledge and understanding together with emphasis on skill and attitude development. The purpose of this study was to allow preregistration students the opportunity to practise key clinical skills prior to clinical placement and test skills acquisition using the model of an objective structured clinical examination (OSCE).

Methods  The learning experience of the student was altered to accommodate a more conceptually‐driven, problem‐centred, case‐based approach. The curriculum was adjusted to incorporate a short clinical skills programme where emphasis was deliberately placed on skill acquisition. At the conclusion of this clinical skills programme, and prior to the students entering clinical placement, skill performance by students was tested using the OSCE. The method of testing was also evaluated by students.

Results  The OSCE was delivered to 37 preclinical students. Four of the test candidates (11%) failed in at least one of the skill areas: these students performed similarly during clinical placement. Twenty‐one (57%) students returned the post‐OSCE questionnaire. Twenty (95%) students reported a positive experience; 20 (95%) students reported initial anxiety that diminished as the test progressed.

Conclusion  The Project Team was confident with the novel approach taken in re‐designing the curriculum: to include a dedicated clinical skills programme, together with addition of the testing of clinical skills using the OSCE model. These curriculum changes were deemed to be highly appropriate additions to the student experience in determination of skill performance of students prior to clinical placement.
Investigation into the nutritional status, dietary intake and smoking habits of patients with chronic obstructive pulmonary disease
Authors: Cochrane W. J. , Afolabi O. A.
Published: January 2004

Background and aims  Weight loss and reduced fat‐free mass are prevalent amongst patients with chronic obstructive pulmonary disease (COPD). However, the causes of this weight loss are not clear. The aims of this study are to investigate the factors affecting body weight and dietary intake in a group of outpatients with COPD, and to investigate any differences between adequately nourished and malnourished patients.

Methods  In 103 stable outpatients, nutritional status was assessed using Body Mass Index (BMI) and upper arm anthropometry. Lung function, smoking status, exercise tolerance, dietary intake, dietary problems and health‐related quality of life were assessed. Patients were classed as either adequately nourished or malnourished.

Results  Twenty‐three per cent of subjects were classed as malnourished. The malnourished subjects had lower lung function measurements, suffered more dietary problems and had lower nutritional intake compared with the adequately nourished subjects. They also had poorer fatigue scores. In linear regression analysis, the factors that had the most effect on BMI were a low transfer factor, presence of early satiety, and being a current smoker.

Conclusion  Important differences were found between adequately nourished and malnourished subjects. These differences move us closer to understanding how best to screen and treat this group of patients.
The development and evaluation of Student Training, Education and Practice for Dietetics CD‐ROM: a computer‐assisted instruction programme for dietetic students
Authors: Herriot A. M. , Bishop J. A. , Truby H.
Published: January 2004

The Student Training, Education and Practice for Dietetics (STEP‐DIET) CD‐ROM was developed at the University of Surrey to prepare dietetic students for the practical dietetic training component of their Nutrition/Dietetics degree. This study aimed to evaluate student response to the programme and its effectiveness as a teaching tool, based on the evaluation framework of D.L. Kirkpatrick (Evaluating a Course, 2nd edn. London, Kogan Page). Quantitative and qualitative methodologies were employed, with 41 dietetic students, separated by year group, completing questionnaires and taking part in six focus groups, at the University of Surrey. Student attitudes towards the instruction method and the STEP‐DIET programme itself were investigated, in conjunction with their perceived learning achievements.

Students rated the programme highly in terms of design and content, however, there was a reluctance to accept computer‐assisted instruction (CAI) as a sole teaching method. A number of learning achievements relevant to dietetic practice were reported including a perceived increase in ability to conduct a dietetic interview and an increased understanding of the management of Type 2 diabetes. In general students reacted positively to the STEP‐DIET programme and it was perceived by students to be effective in preparing them for the practical component of their dietetic training.
A survey to assess physical activity promotion by Registered Dietitians
Authors: McKenna J. , Henderson L. , Baic S.
Published: January 2004

Background  Convincing evidence has emerged in recent years for the role of physical activity (PA) in the prevention and treatment of many chronic diseases. These include both physical and mental health problems, which are likely to be encountered by practicing dietitians. This study aimed to identify whether NHS based Registered Dietitians (RDs) currently promote PA to their patients and if so, how they do it and with which patients.

Method  An anonymous questionnaire sent to 516 RDs in NHS teaching hospitals achieved a 77% (n = 397) return rate.

Results  Ninety‐three per cent of respondents reported regularly promoting PA particularly with new patients. Among active PA promoters, 87% reported encouraged daily accumulation of PA, 50% focused on sport and exercise and 52% referred patients to GPs or Physiotherapists for advice.

Distinctive levels and styles of PA promotion were found to be related to levels of recent training in the field although fewer than one in four had actually received any formal training.

Conclusions  A high interest in further PA‐specific training (95% of all respondents), together with high variability in the type and quality of advice suggests the need to develop further in‐service training specifically for RDs.
Impact of tea drinking on iron status in the UK: a review
Authors: Nelson M. , Poulter J.
Published: January 2004

Background The aims of this review are (1) to evaluate the literature on the likely impact of tea drinking on the iron status of different groups within the UK population and (2) to formulate targeted and evidence based advice on tea drinking in the context of iron nutrition in different groups of people.

Method A literature search identified 35 references specific to the effects of black tea on iron absorption and iron nutrition plus one recent review article. Each study was assessed in terms of methodogical quality and relevance to the tea drinking patterns of the UK population.

Results There is clear evidence to show that tea drinking limits the absorption of nonhaem iron. However, there are few studies which have assessed the influence of tea drinking on indicators of iron status. There are no intervention studies and the conclusions reported in this review are based on 12 observational studies mostly from other countries. These studies have reported either significant negative correlations between tea drinking and blood indicators of iron status or more cases of anemia in tea drinkers compared with nontea drinkers. Many of the studies reviewed report additional relationships between iron status indices and other factors (both dietary and nondietary), highlighting the complexity of influences on iron absorption and iron status.

Conclusion From the available evidence there is no need to advise any restriction on tea drinking in healthy people with no risk of iron deficiency. In groups at risk of iron deficiency the advice should be to drink tea between meals and to wait at least 1 h after eating before drinking tea.
The opinion of Dutch dietitians about functional foods
Authors: De Jong N. , Hoendervangers C. T. , Bleeker J. K. , Ocké M. C.
Published: January 2004

Objective  To obtain information about Dutch dietitian's attitudes, perceived knowledge, training preferences, counselling procedures, opinions about post‐launch monitoring, and personal consumption of functional foods.

Design  A self‐administered, 62‐item, postal survey in 2002.

Subjects  Five hundred randomly selected registered dietitians. The response rate was 49% (n = 238).

Results  The responders (mean age ± SD: 40 ± 9 years) had regular contact with clients (90%), and many (71% of 90%) advised about functional food use. Sixty‐nine per cent hardly consumed any functional food themselves. Eighty‐seven per cent of the responders would greatly appreciate courses given by scientists. Confusion existed about usage practices, target groups, safety, efficacy, and claims: between 42 and 89% agreed with the statements about uncertainties. Nonetheless, 69% felt that functional foods could theoretically contribute to good bodily functioning. Ninety per cent thought post‐launch monitoring (PLM) important, but ideas about a common dietetic contribution to PLM did not emerge.

Conclusions  Although functional foods potentially contribute to a healthful diet, there is still confusion among dietitians about claims, safety, efficacy and product‐handling aspects. It is time to meet dietitians’ repeated requests to provide education by noncommercial experts. In the meantime, dietitians themselves should have more say in the PLM debate because they should and could play an important role.
Test strip detection of Wuchereria bancrofti amplified DNA in wild‐caught Culex pipiens and estimation of infection rate by a PoolScreen algorithm
Authors: Helmy Hanan , Fischer Peter , Farid Hoda A. , Bradley Mark H. , Ramzy Reda M. R.
Published: January 2004

Bancroftian filariasis is targeted for elimination in the Nile Delta of Egypt. Improved simple methods are needed for monitoring Wuchereria bancrofti infection in the mosquito vector and thereby the success of elimination programmes. We evaluated the performance of the SspI‐PCR assay combined with a DNA Detection Test StripTM method and used the PoolScreen algorithm method for estimating mosquito infection rates. A total of 769 indoor‐resting Culex pipiens were captured in 79 randomly selected houses from a filaria‐endemic village in the Nile Delta of Egypt (24.4% antigenaemia and 8.6% microfilaraemia). Collected mosquitoes were pooled by house, and assayed by the SspI‐PCR. Amplified parasite DNA was detected by both electrophoresis of agarose gel stained with ethidium bromide (EtBr) and by test strips. PCR based on EtBr and test strip methods identified 43 (54.4%) and 45 (56.9%) houses, respectively, as being filaria positive. The minimum mosquito infection rate, assuming one infected female/pool was 6.85% by the PCR test strips. Mosquito infection rate calculated by the PoolScreen2 algorithm software amounted to 8.1% [95% confidence interval 5.85, 10.47]. Because it is faster and safer, the PCR test strip is a practical tool, especially when combined with the PoolScreen algorithm method, for xenomonitoring the success of elimination programmes.
Pregnancy interval and delivery outcome among HIV‐seropositive and HIV‐seronegative women in Kisumu, Kenya
Authors: van Eijk Anna M. , De Cock Kevin M. , Ayisi John G. , Rosen Daniel H. , Otieno Juliana A. , Nahlen Bernard L. , Steketee Richard W.
Published: January 2004

Objective  A short pregnancy interval (PI) has been associated with increased child mortality, but mechanisms are unclear. We studied factors associated with PI and the effect of PI on birthweight and haemoglobin.

Methods  Information was analysed from 2218 multigravidae who were recruited at the prenatal clinic (1758) or in the labour ward (460) of the Provincial Hospital in Kisumu between June 1996 and July 2000 for a study to assess the interaction between placental malaria and vertical HIV transmission.

Results  The HIV prevalence was 28.9%. HIV seropositivity, older age, being unmarried, and <8 years of education were associated with a prolonged PI; among all women, a stillbirth, abortion, or death of a liveborn child as outcome of the previous pregnancy, and death of a child other than the last born among HIV‐seronegative women, were associated with a shortened PI. No significant effect of short PI (an interval <24 months) on low birth weight (LBW), prematurity, small‐for‐gestational‐age infants or maternal anaemia was evident. An abortion, stillbirth, or death of a liveborn child as outcome of the previous pregnancy was associated at the present delivery with LBW among HIV‐seronegative women [adjusted odds ratio (AOR) 3.33, 95% confidence interval (CI) 1.63–6.81], and a low haemoglobin (<11 g/dl) among HIV‐seropositive women (AOR 2.01, 95% CI 1.05–4.03 in the third trimester).

Conclusion  Public health efforts to ensure ‘adequate’ birth spacing may run contrary to family planning decisions to replace a deceased child and may be spent on prenatal issues like prevention of anaemia, and vertical HIV transmission.
Anti‐p200‐Pemphigoid – Eine neue blasenbildende Autoimmundermatose
Authors: Shimanovich Iakov , Rose Christian , Hirako Yoshiaki , Butt‐Dörje Elke , Zillikens Detlef
Published: January 2004

Das Anti‐p200‐Pemphigoid ist eine neue Autoimmunerkrankung der Haut, die klinisch durch pralle Blasen und histopathologisch durch eine subepidermale Spaltbildung mit einer überwiegend neutrophilen Infiltration der dermo‐epidermalen Junktionszone (DEJ) gekennzeichnet ist. Die direkte Immunfluoreszenz periläsionaler Hautbiopsien zeigt lineare Ablagerungen von IgG und C3 entlang der DEJ, während sich mittels indirekter Immunfluoreszenz zirkulierende IgG‐Antikörper gegen die dermale Seite NaCl‐gespaltener normaler Haut nachweisen lassen. Das Zielantigen der Autoantikörper ist ein 200 kD schweres Protein (p200) der unteren Lamina lucida, welches im Immunoblot mit Extrakten humaner Dermis erkannt wird. Die genaue Identität von p200, das offensichtlich eine wichtige Funktion für die Zell‐Matrix‐Adhäsion hat, ist noch unklar. Die bisherigen Untersuchungen konnten dieses Autoantigen jedoch von BP180, BP230, Laminin 1, 5 und 6, α6β4‐Integrin und Typ‐VII‐Kollagen abgrenzen. Die biochemische Charakterisierung von p200 zeigte, daß es sich hierbei um ein nichtkollagenes, N‐glykosiliertes, saueres Protein mit einem isoelektrischen Punkt von ca. 5,5 handelt. Die vorliegende Arbeit gibt einen Überblick zu Pathogenese, Klinik, Diagnostik und Therapie dieser neuen Autoimmundermatose.
Low dose isotretinoin combined with tretinoin is effective to correct abnormalities of acne
Authors: Plewig Gerd , Dressel Heidrun , Pfleger Maike , Michelsen Silke , Kligman Albert M.
Published: January 2004

Zusammenfassung/Summary

Background: Isotretinoin is well known in the therapy of acne papulopustulosa and acne conglobata. No study has investigated the pathophysiological changes of the skin of acne patients, especially when low dose oral isotretinoin is given in combination with topical tretinoin.

Patients and methods: 28 patients were treated for 6 months with oral isotretinoin. In the acne conglobata group (A – C) patients were treated with 10 mg (Group A) or 20 mg isotretinoin (Groups B, C) in combination with topical 0.05 % tretinoin cream. Group C was treated the first 2 weeks with 0.05 % betamethasone valerate cream instead of tretinoin cream. In the acne papulopustulosa group, the patients received 0.5 mg isotretinoin/kg bodyweight and 0.05 % tretinoin cream, either alone (Group E), or with oral methylprednisolone during induction (Group D).

Results: Acne conglobata – A reduction of inflammatory lesion by 87 – 94 % and of non‐inflammatory lesions by 81 – 88 % was achieved (Groups A – C). A reduction of sebaceous gland size by 35 – 58 %, sebum production by 90 – 95 %, follicular keratinization by 55 – 70 % and Propionibacteria by 33 – 73 % was seen (Groups B and C better than Group A). In Group A the amount of lipids was only reduced by 6 %, in Group B by 35 % and in Group C by 40 %.

Acne papulopustulosa – Sebum excretion rate and follicular keratinization were reduced in Group D by 89 % and 50 % respectively, with isotretinoin alone by 94 % and 53 %. The amount of lipids was reduced in Group D by 40 % and in Group E by 21 %.

Conclusions: Because of the efficacy and cost‐benefit relationship of isotretinoin in the treatment of acne compared to other therapeutic approaches, further use low dose isotretinoin in the described settings seems to justified.
DRGs in der Dermatologie: Ergebnisse des DRG‐Evaluationsprojektes der Deutschen Dermatologischen Gesellschaft
Authors: Fürstenberg Torsten , Rompel Rainer , Gollnick Harald , Sterry Wolfram , Luger Thomas A. , Hensen Peter , Roeder Norbert
Published: January 2004

Hintergrund: Die Einführung des DRG‐Systems in Deutschland optional ab dem 1. 1. 2003 und für alle Krankenhäuser verpflichtend ab dem 1. 1. 2004 hat zu einer großen Verunsicherung v. a. auf der Krankenhausseite geführt, da befürchtet wird, daß die in Deutschland praktizierten diagnostischen und therapeutischen Maßnahmen sich nicht sachgerecht mit einem DRG‐System abbilden und vergüten lassen. Daher hat die Deutsche Dermatologische Gesellschaft ein DRG‐Evaluationsprojekt in Zusammenarbeit mit der DRG‐Research‐Group des Universitätsklinikums Münster und der Bundesärztekammer mit dem Ziel durchgeführt, die medizinische und ökonomische Homogenität der Fallgruppen zu überprüfen.

Patienten und Methodik: 19 403 Fälle dermatologischer Abteilungen aus 19 Krankenhäusern – zehn universitäre und neun nicht‐universitäre Häuser – wurden über einen viermonatigen Erhebungszeitraum prospektiv gesammelt und hinsichtlich ihrer Leistungs‐, Verweildauer‐ und Aufwandshomogenität untersucht.

Ergebnisse: Die resultierende Datenlage bildet die Basis für den Nachweis möglicher Defizite der Abbildung dermatologischer Fälle im G‐DRG‐System. Aufgrund dieser Datenbasis wurden 10 Anpassungsvorschläge formuliert und fristgerecht zum 31. 3. 2003 beim Institut für das Entgeltsystem im Krankenhaus (InEK gGmbH) eingereicht.

Schlußfolgerungen: Mit den Ergebnissen des DRG‐Evaluationsprojektes konnte aufgezeigt werden, daß das G‐DRG‐System der Version 1.0 nicht über die ausreichende Differenzierung verfügt, um die vielfältigen diagnostischen und therapeutischen Leistungen der Dermatologie mit ihren Spezialgebieten in Deutschland mit einem angemessenen Differenzierungsgrad abzubilden.
G‐DRG Version 2004: Veränderungen aus Sicht der Dermatologie
Authors: Hensen Peter , Fürstenberg Torsten , Irps Sebastian , Grabbe Stephan , Schwarz Thomas , Luger Thomas A. , Rompel Rainer , Roeder Norbert
Published: January 2004

Die Finanzierung der stationären Krankenhausleistungen über ein DRG‐basiertes Vergütungssystem wird ab 2004 für alle Krankenhäuser verpflichtend eingeführt. Nachdem mit der Krankenhausfallpauschalenverordnung 2004 (KFPV 2004) die zentralen Punkte der G‐DRG‐Systemversion bekannt geworden sind, stellt sich die Frage nach den Konsequenzen. Festzustellen ist, daß der erste deutsche DRG‐Fallpauschalenkatalog sich sehr deutlich von dem bisherigen Optionskatalog unterscheidet, so daß eine intensive Auseinandersetzung mit den neuen Bedingungen erforderlich wird. Medizinökonomisches Handeln wird stärker als bisher den Krankenhausalltag prägen und Einfluß nehmen auf sich verändernde Versorgungsstrukturen. Die wesentlichen Grundlagen und die Anwendung der neuen Bestimmungen müssen deshalb bekannt sein. Neben den allgemeinen Abrechnungsregeln werden vor allem die Veränderungen im neuen Fallpauschalenkatalog erläutert und Auswirkungen für die Dermatologie beispielhaft beleuchtet. Weiterhin müssen die Klassifikationssysteme in den Versionen OPS‐301 SGB V und ICD‐10‐GM 2004 sowie die Deutschen Kodierrichtlinien Version 2004 Berücksichtigung finden. Daher werden ebenso die wesentlichen Neuerungen im Verwendungszusammenhang für die Dermatologie vorgestellt.
A refined technique for determining the respiratory gas exchange responses to anaerobic metabolism during progressive exercise – repeatability in a group of healthy men
Authors: Wisén Anita G. M. , Wohlfart Björn
Published: January 2004

The respiratory gas exchange and ventilation during an incremental cycle exercise test were analysed in a group of 19 healthy, moderately fit men. Different computer algorithms were used to estimate the V̇O2 values where: (i) the rate of V̇CO2 increase just exceeds the rate of V̇O2 increase (DX, derivative crossing), (ii) V̇CO2/V̇O2 = 1·00 (PX, point of crossing) and (iii) ventilation (V̇E) increases disproportionately in relation to V̇CO2 (PQ, point of V̇CO2 equivalent rise). The DX and PQ measurements were analysed using a new approach employing polynomial regression and the value of PX was determined following low‐pass filtration of raw data. The repeatability of the measurements was evaluated with a 5–6 week interval between the tests. The correlations between tests were 0·75 at DX, 0·85 at PX and 0·62 at PQ. The mean differences between the repeated tests were not statistically significant. The repeatability of V̇O2, in absolute values expressed as ±2 SD of the differences between the tests, had values of 5·0, 6·1 and 9·5 ml min−1 kg−1 for DX, PX and PQ, respectively. The mean value of V̇O2 for each measurement point expressed as a percentage of V̇O2max was 54% at DX, 68% at PX and 70% at PQ. The most common sequence of the measured values was DX < PX < PQ, but the sequence DX < PQ < PX was also observed. It is concluded that the gas exchange responses to developing anaerobic metabolism during progressive exercise can be characterized by a series of thresholds. However, the considerable variation in absolute values in the two testing occasions requires further attention.
Decrease in heart rate variability with overtraining: assessment by the Poincaré plot analysis
Authors: Mourot Laurent , Bouhaddi Malika , Perrey Stéphane , Cappelle Sylvie , Henriet Marie‐Thérèse , Wolf Jean‐Pierre , Rouillon Jean‐Denis , Regnard Jacques
Published: January 2004

Numerous symptoms have been associated with the overtraining syndrome (OT), including changes in autonomic function. Heart rate variability (HRV) provides non‐invasive data about the autonomic regulation of heart rate in real‐life conditions. The aims of the study were to: (i) characterize the HRV profile of seven athletes (OA) diagnosed as suffering of OT, compared with eight healthy sedentary (C) and eight trained (T) subjects during supine rest and 60° upright, and (ii) compare the traditional time‐ and frequency‐domain analysis assessment of HRV with the non‐linear Poincaré plot analysis. In the latter each R‐R interval is plotted as a function of the previous one, and the standard deviations of the instantaneous (SD1) and long‐term R‐R interval variability are calculated. Total power was higher in T than in C and OA both in supine (1158 ± 1137, 6092 ± 3554 and 2970 ± 2947 ms2 for C, T and OA, respectively) and in upright (640 ± 499, 1814 ± 806 and 1092 ± 712 ms2 for C, T and OA, respectively; P<0·05) positions. In supine position, indicators of parasympathetic activity to the sinus node were higher in T compared with C and OA (high‐frequency power: 419·1 ± 381·2, 1105·3 ± 781·4 and 463·7 ± 715·8 ms2 for C, T and OA, respectively; P<0·05; SD1: 29·5 ± 18·5, 75·2 ± 17·2 and 37·6 ± 27·5 for C, T and OA, respectively; P<0·05). OA had a marked predominance of sympathetic activity regardless of the position (LF/HF were 0·47 ± 0·35, 0·47 ± 0·50 and 3·96 ± 5·71 in supine position for C, T and OA, respectively, and 2·09 ± 2·17, 7·22 ± 6·82 and 12·04 ± 10·36 in upright position for C, T and OA, respectively). The changes in HRV indexes induced by the upright posture were greater in T than in OA. The shape of the Poincaré plots allowed the distinction between the three groups, with wide and narrow shapes in T and OA, respectively, compared with C. As Poincaré plot parameters are easy to compute and associated with the ‘width’ of the scatter gram, they corroborate the traditional time‐ and frequency‐domain analysis. We suggest that they could be used to indicate fatigue and/or prevent OT.
Neonatal ACE inhibition in rats interferes with lung development
Authors: Lasaitiene Daina , Chen Yun , Nannmark Ulf , Wollmer Per , Friberg Peter
Published: January 2004

The renin–angiotensin system (RAS) is developmentally up‐regulated and it is essential for kidney development in several species. Given the fact that the rat lung undergoes postnatal development, the mammalian lung possesses the highest angiotensin‐converting enzyme (ACE) levels and ACE activity increases during the first weeks postpartum, we tested the hypothesis that ACE inhibition influences postnatal lung development. Rats were given the ACE inhibitor enalapril (10 mg kg−1) from 0 to 9 days of age and their lungs were examined at day 4 and 9. Lung structure was evaluated by means of light microscopy, and surface tension of bronchoalveolar lavage fluid was measured by means of a Wilhelmy balance. Neonatal ACE inhibition lowered the surface tension of bronchoalveolar lavage fluid and caused widening of respiratory airspaces and thinning of alveolar septa. Our results suggest that early postnatal ACE inhibition in rats interferes with lung development.
Temperature-dependent contact resistances in high-quality polymer field-effect transistors
Authors: Hamadani B. H. , Natelson D.
Published: January 2004

Contact resistances between organic semiconductors and metals can dominate the transport properties of electronic devices incorporating such materials. We report measurements of the parasitic contact resistance and the true channel resistance in bottom contact poly(3-hexylthiophene) field-effect transistors with channel lengths from 400 nm up to 40 μm, from room temperature down to 77 K. For fixed gate voltage, the ratio of contact to channel resistance decreases with decreasing temperature. We compare this result with a recent model for organic semiconductor-metal contacts. Mobilities corrected for this contact resistance can approach 1 cm2/V s at room temperature and high gate voltages.
Use of deposition pressure to control residual stress in polycrystalline SiC films
Authors: Fu Xiao-An , Jezeski Ronald , Zorman Christian A. , Mehregany Mehran
Published: January 2004

Polycrystalline silicon carbide (poly-SiC) thin films were grown in a large-volume, low pressure chemical vapor deposition furnace using dichlorosilane and acetylene precursors. The deposition temperature was fixed at 900 °C and the pressure was varied between 0.46 and 5 Torr. The residual stress of as-deposited SiC films ranged from highly tensile to moderately compressive as the deposition pressure was increased from 0.46 to 5 Torr, with tensile stress below 50 MPa in films deposited at around 2.5 Torr. Cantilever beams with no vertical deformation were fabricated from the low tensile stress films, and they indicated that the stress gradient was also very low in these films. X-ray diffraction analysis indicated that all the films were highly textured polycrystalline (111) 3C-SiC regardless of the residual stress. Transmission electron microscopy indicated that both the tensile and compressive films were columnar in microstructure, with slight differences in the axial alignment of the grains with respect to the film/substrate interface as well as in the density of features in the grain boundaries. An explanation for the observed differences in residual stress based on differences in film microstructure is proposed.
High fluorescence quantum efficiency of 1.8 μm emission in Tm-doped low silica calcium aluminate glass determined by thermal lens spectrometry
Authors: Oliveira S. L. , Lima S. M. , Catunda T. , Nunes L. A. O. , Rohling J. H. , Bento A. C. , Baesso M. L.
Published: January 2004

In this work, thermal lens spectrometry is performed to determine the fluorescence quantum efficiency (η) of the F43 level (1.8 μm emission) of 4 and 5 wt % Tm-doped water free low silica calcium aluminate glass. The η value obtained for both high Tm contents was approximately 30%, which is in agreement with the Judd–Ofelt calculation. It is also verified that heat generation under 0.79 μm pumping, which presents a high quantum defect, is minimized by a cross-relaxation mechanism. The high η values, and the excellent chemical and thermomechanical properties indicate this system is a potential host material for diode-pumped laser sources operating in the midinfrared spectral range.
Circuit with small-capacitance high-quality Nb Josephson junctions
Authors: Watanabe Michio , Nakamura Yasunobu , Tsai Jaw-Shen
Published: January 2004

We have developed a fabrication process for nanoscale tunnel junctions which includes focused-ion-beam etching from different directions. By applying the process to a Nb/(Al–)Al2O3/Nb trilayer, we have fabricated a Nb single-electron transistor (SET), and characterized the SET at low temperatures, T=0.04–40 K. The superconducting gap energy and the transition temperature of the Nb SET agree with the bulk values, which suggests high quality Nb junctions. The single-electron charging energy of the SET is estimated to be larger than 1 K.
High critical current density and its field dependence in mixed rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ thin films
Authors: Cai C. , Holzapfel B. , Hänisch J. , Fernández L. , Schultz L.
Published: January 2004

Compared with mono-rare earth 123 films, ternary rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ (NEG123) films show higher critical current density (Jc) and improved irreversibility field (Hirr), but no increase in the characteristic field corresponding to a crossover from a low-field plateau to a linear region in a log Jc–log H plot. At intermediate fields, Jc vs H scales as H(−0.5±0.05) for NEG123, in contrast to H(−0.73±0.05) for mono-rare earth samples such as Gd123. The slow power decay of Jc vs H together with the improved Jc and Hirr strongly implies that extra flux pinning centers exist in NEG123, which are thought to be noncorrelated stress fields induced by lattice mismatch.
Composite nanogranular films of FePt-MgO with (001) orientation onto glass substrates
Authors: Kang K. , Zhang Z. G. , Papusoi C. , Suzuki T.
Published: January 2004

For perpendicular magnetic recording, a design of using MgO as a seed layer and an intermediate layer is introduced. By annealing the multilayer film with a stack structure of MgO/[FePt/MgO]3 at 600 °C for 1 min, nanograins of FePt with a high perpendicular magnetic anisotropy are obtained on a glass substrate. This high magnetic anisotropy results from the (001) texture of L10 phase developed along the film normal. A thin MgO layer ranging 1.0 to 3.0 nm in thickness plays an important role in developing the (001) texture of L10 FePt and magnetically decoupling the FePt particles. Varying a layer thickness of the FePt layer enables to control the crystalline structure and the magnetic properties, resulting in the films with a controllable FePt grain size as small as several nanometers, a high remanence squareness, and a high coercivity.
Germanium-concentration dependence of arsenic diffusion in silicon germanium alloys
Authors: Eguchi S. , Chleirigh C. N. , Olubuyide O. O. , Hoyt J. L.
Published: January 2004

The germanium-concentration dependence of arsenic diffusion in relaxed silicon germanium (Si1−xGex) alloys with Ge content ranging from 0 to 40% has been investigated. Arsenic was implanted into relaxed epitaxial layers at 15 keV to a dose of 3×1015 cm−2, and diffusion during furnace and rapid thermal annealing was studied. Under equilibrium extrinsic conditions, the arsenic diffusivity increases exponentially with increasing Ge content in Si1−xGex. Under transient diffusion conditions, the arsenic diffusivity in Si1−xGex is retarded compared to the diffusivity for longer times, while a slight transient enhancement of As diffusion is observed in Si. The degree of transient retardation depends on the germanium concentration in the alloy.
Switching by point-contact spin injection in a continuous film
Authors: Chen T. Y. , Ji Y. , Chien C. L.
Published: January 2004

Spin-polarized currents injected through a point-contact into a continuous Co/Cu/Co trilayer film can reversibly switch the magnetization of small magnetic bits in the top Co layer. The magnetic states written depend on the polarity of the injection currents, and remain stable at room temperature. The reversible writing can be achieved for a wide range of contact resistances with a well-defined voltage for the reversal.
Interfacial disorder in the L1 FePt particles capped with amorphous Al2O3
Authors: Takahashi Y. K. , Hono K.
Published: January 2004

L1 0 -FePt particles disorder at the interface when an amorphous Al2O3 layer is capped on an ordered FePt particulate film at room temperature. The coercivity decreases drastically as a result. Interfacial disordering does not progress when the capped layer is deposited at elevated temperature, indicating that the disordering is driven by the strain at the interface. The FePt particulate film becomes magnetized more easily by the Al2O3 capping.
Roughness and stability of silicon on insulator surfaces
Authors: Czubanowski M. , Tegenkamp C. , Ernst W. , Pfnür H.
Published: January 2004

The feasibility of low temperature processes (below 800 °C) to obtain in situ atomically clean and smooth surfaces on (100) oriented silicon on insulator material (SOI) with negligible variation of the top Si film thickness was tested. These steps were characterized using low-energy electron diffraction and atomic force microscopy supplemented by conductivity measurements. The most promising method for obtaining atomically smooth and continuous SOI films is the evaporation of Si at 750 °C at a flux of 0.15 ML/min. For lower rates [113]-oriented pits are formed within the SOI layer. It turned out that mobile and volatile oxide formation at the Si/SiO2 interface in these materials can occur already at temperatures below 1000° C, leading to the destruction of the buried oxide layer.
Electra: Repetitively pulsed, 500 J, 100 ns, KrF oscillator
Authors: Wolford M. F. , Hegeler F. , Myers M. C. , Giuliani J. L. , Sethian J. D.
Published: January 2004

Electra is a repetitively pulsed, double-sided, electron-beam pumped krypton fluoride laser. Electra has recently operated as an oscillator with an output pulse of 510 J, with 100 ns pulse duration for single shots. At a 1 Hz repetition rate for a ten-shot burst, the laser output averaged 500 J per shot. The dependence of the laser energy on the partial pressures of Kr, Ar, and F2 were examined. Over a 10 to 30 psi total pressure range, the laser output energy decreases with decreasing argon concentration. Specifically, the laser output drops slightly as the argon concentration reduces from 60% to 40%, and then drops more noticeably as it is reduced to 0%. For the 60% Ar case, the optimal fluorine concentration is 0.25%, with a significant falloff in the laser energy from 0.25% to 0.1% and a gradual falloff from 0.25% to 0.7% fluorine. The present burst results indicate that the KrF kinetics is not very sensitive to the gas temperature at a total pressure of 20 psi.
Highly efficient continuous-wave operation at 1030 and 1075 nm wavelengths of LD-pumped Yb3+:Y2O3 ceramic lasers
Authors: Takaichi Kazunori , Yagi Hideki , Lu Jianren , Bisson Jean-Francois , Shirakawa Akira , Ueda Ken-ichi , Yanagitani Takagimi , Kaminskii Alexander A.
Published: January 2004

Room-temperature cw laser oscillations at 1030 and 1075 nm wavelengths were demonstrated for the TEM00 mode with Yb3+:Y2O3 ceramics by LD-pumping. A maximum extraction efficiency of 72% at 1075 nm lasing wavelengths and of 45% at 1030 nm lasing wavelengths were observed.
Deep ultraviolet scanning near-field optical microscopy for the structural analysis of organic and biological materials
Authors: Aoki Hiroyuki , Hamamatsu Toyohiro , Ito Shinzaburo
Published: January 2004

Scanning near-field optical microscopy (SNOM) using a deep ultraviolet (DUV) light source was developed for in situ imaging of a variety of chemical species without staining. Numerous kinds of chemical species have a carbon–carbon double bond or aromatic group in their chemical structure, which can be excited at the wavelength below 300 nm. In this study, the wavelength range available for SNOM imaging was extended to the DUV region. DUV–SNOM allowed the direct imaging of polymer thin films with high detection sensitivity and spatial resolution of several tens of nanometers. In addition to the polymer materials, we demonstrated the near-field imaging of a cell without using a fluorescence label.
Organic light-emitting diodes formed by soft contact lamination
Authors: Lee Tae-Woo , Zaumseil Jana , Bao Zhenan , Hsu Julia W. P. , Rogers John A.
Published: January 2004

Although tremendous progress has been made in organic light-emitting diodes (OLEDs), with few exceptions they are fabricated in the standard way by sequentially depositing active layers and electrodes onto a substrate. Here we describe a different approach for building OLEDs, which is based on physical lamination of thin metal electrodes supported by an elastomeric layer against an electroluminescent organic. This method relies only on van der Waals interactions to establish spatially homogeneous, intimate contacts between the electrodes and the organic. We find that devices fabricated in this manner have better performance than those constructed with standard processing techniques. The lamination approach avoids forms of disruption that can be introduced at the electrode/organic interface by metal evaporation and has a reduced sensitivity to pinhole or partial pinhole defects. In addition, because this form of “soft” contact lamination is intrinsically compatible with the techniques of soft lithography, it is easy to build patterned OLEDs with feature sizes into the nanometer regime. This method provides a new route to OLEDs for applications ranging from high performance displays to storage and lithography systems that rely on subwavelength light sources.
Somatic activation of oncogenic
Kras
in hematopoietic cells initiates a rapidly fatal myeloproliferative disorder
Authors: Braun Benjamin S. , Tuveson David A. , Kong Namie , Le Doan T. , Kogan Scott C. , Rozmus Jacob , Le Beau Michelle M. , Jacks Tyler E. , Shannon Kevin M.
Published: January 2004

RAS
mutations are common in myeloid malignancies; however, it is not known whether oncogenic
RAS
can initiate leukemia. We show that expressing mutant K-Ras
G12D
protein from the endogenous murine locus rapidly induces a fatal myeloproliferative disorder with 100% penetrance characterized by tissue infiltration, hypersensitivity to growth factors, and hyperproliferation. Hematopoietic cells from diseased mice demonstrated increased levels of Ras-GTP, but effector kinases were not constitutively phosphorylated and responded normally to growth factors. Oncogenic
RAS
is sufficient to initiate myeloid leukemogenesis in mice, and this provides an
in vivo
system for biologic and preclinical studies.
Myc-interacting protein 1 target gene profile: A link to microtubules, extracellular signal-regulated kinase, and cell growth
Authors: Ziegelbauer Joseph , Wei Joyce , Tjian Robert
Published: January 2004

To study the role of the transcription factor Myc-interacting protein 1 (MIZ-1) in activating various target genes after induction with the microtubule disrupting agent T113242, we have used small interfering RNA duplexes (siRNAs) to knockdown the expression of MIZ-1. As expected, depletion of MIZ-1 resulted in the inhibition of T113242-dependent activation of the low-density lipoprotein receptor (LDLR) gene in hepatocytes. Cells transfected with MIZ-1 siRNAs also exhibited growth arrest. In addition, inhibition of the extracellular signal-regulated kinase (ERK) pathway inhibited T113242-induced nuclear accumulation of MIZ-1 and activation of LDLR. Gene expression microarray analysis under various induction conditions identified other T113242-activated genes affected by a decrease in MIZ-1 and inhibition of the ERK pathway. We also found that the accumulation of MIZ-1 in the nucleus is influenced by cell–cell contact and/or growth. Taken together, our studies suggest that MIZ-1 regulates a specific set of genes that includes LDLR and that the ERK pathway plays a role in the activation of target promoters by MIZ-1.
Nonrandom HIV-1 infection and double infection via direct and cell-mediated pathways
Authors: Dang Que , Chen Jianbo , Unutmaz Derya , Coffin John M. , Pathak Vinay K. , Powell Douglas , KewalRamani Vineet N. , Maldarelli Frank , Hu Wei-Shau
Published: January 2004

Cells infected with two related retroviruses can generate heterozygous virions, which are the precursors of recombinant proviruses. Although many studies have focused on the frequencies and mechanisms of retroviral recombination, little is known about the dynamics of double infection. To examine this issue, viruses generated from two HIV-1 vectors containing different markers were mixed together, and were used to infect target cells. The numbers of cells expressing none, one, or both markers were measured and were used to calculate whether double infection occurred at frequencies expected from random infection events. We found that double infection occurred significantly more frequently than predicted from random distribution; increased rates of double infection were observed in both a T cell line and primary activated CD4
+
T cells. In addition to direct virus infection, we also examined the nature of cell-mediated HIV-1 double infection. Increased double infection was observed in all experiments regardless of whether a cell line or primary human dendritic cells were used for capture and transmission of HIV-1. Therefore, our results indicate that HIV-1 double infection occurs more frequently than it would at random in both direct and cell-mediated HIV-1 infections. To our knowledge, this is the first direct evidence of nonrandom double infection in HIV-1. Frequent double HIV-1 infections in infected individuals would allow the generation of recombinant viruses that could then affect their pathogenesis and evolution.
The chitinolytic cascade in Vibrios is regulated by chitin oligosaccharides and a two-component chitin catabolic sensor/kinase
Authors: Li Xibing , Roseman Saul
Published: January 2004

Chitin, a highly insoluble polymer of GlcNAc, is produced in massive quantities in the marine environment. Fortunately for survival of aquatic ecosystems, chitin is rapidly catabolized by marine bacteria. Here we describe a bacterial two-component hybrid sensor/kinase (of the ArcB type) that rigorously controls expression of ≈50 genes, many involved in chitin degradation. The sensor gene,
chi
S, was identified in
Vibrio furnissii
and
Vibrio cholerae
(predicted amino acid sequences, full-length: 84% identical, 93% similar). Mutants of
chi
S grew normally on GlcNAc but did not express extracellular chitinase, a specific chitoporin, or β-hexosaminidases, nor did they exhibit chemotaxis, transport, or growth on chitin oligosaccharides such as (GlcNAc)
2
. Expression of these systems requires three components: wild-type
chi
S; a periplasmic high-affinity
c
hitin oligosaccharide, (GlcNAc)
n
(
n
> 1),
b
inding
p
rotein (CBP); and the environmental signal, (GlcNAc)
n
. Our data are consistent with the following model. In the uninduced state, CBP binds to the periplasmic domain of ChiS and “locks” it into the
minus
conformation. The environmental signal, (GlcNAc)
n
, dissociates the complex by binding to CBP, releasing ChiS, yielding the
plus phenotype
(expression of chitinolytic genes). In
V. cholerae
, a cluster of 10 contiguous genes (VC0620–VC0611) apparently comprise a (GlcNAc)
2
catabolic operon. CBP is encoded by the first, VC0620, whereas VC0619–VC0616 encode a (GlcNAc)
2
ABC-type permease. Regulation of
chi
S requires expression of CBP but not (GlcNAc)
2
transport. (GlcNAc)
n
is suggested to be essential for signaling these cells that chitin is in the microenvironment.
Role of prostaglandin E
2
-dependent angiogenic switch in cyclooxygenase 2-induced breast cancer progression
Authors: Chang Sung-Hee , Liu Catherine H. , Conway Rebecca , Han David K. , Nithipatikom Kasem , Trifan Ovidiu C. , Lane Timothy F. , Hla Timothy
Published: January 2004

Overexpression of human cyclooxygenase 2 (COX-2) in the mammary glands of transgenic mice induces tissue-specific tumorigenic transformation. However, the molecular mechanisms involved are not yet defined. Here we show that COX-2 expressed in the epithelial cell compartment regulates angiogenesis in the stromal tissues of the mammary gland. Microvessel density increased before visible tumor growth and exponentially during tumor progression. Inhibition of prostanoid synthesis with indomethacin strongly decreased microvessel density and inhibited tumor progression. Up-regulation of angiogenic regulatory genes in COX-2 transgenic mammary tissue was also potently inhibited by indomethacin treatment, suggesting that prostanoids released from COX-2-expressing mammary epithelial cells induce angiogenesis. G protein-coupled receptors for the major product, prostaglandin E
2
(PGE
2
) EP
1-4
, are expressed during mammary gland development, and EP
1,2,4
receptors were up-regulated in tumor tissue. PGE
2
stimulated the expression angiogenic regulatory genes in mammary tumor cells isolated from COX-2 transgenic mice. Such cells are tumorigenic in nude mice; however, treatment with Celecoxib, a COX-2-specific inhibitor, reduced tumor growth and microvessel density. These results define COX-2-derived PGE
2
as a potent inducer of angiogenic switch during mammary cancer progression.
In silicodissection of cell-type-associated patterns of gene expression in prostate cancer
Authors: Stuart Robert O. , Wachsman William , Berry Charles C. , Wang-Rodriguez Jessica , Wasserman Linda , Klacansky Igor , Masys Dan , Arden Karen , Goodison Steven , McClelland Michael , Wang Yipeng , Sawyers Anne , Kalcheva Iveta , Tarin David , Mercola Dan
Published: January 2004

Prostate tumors are complex entities composed of malignant cells mixed and interacting with nonmalignant cells. However, molecular analyses by standard gene expression profiling are limited because spatial information and nontumor cell types are lost in sample preparation. We scored 88 prostate specimens for relative content of tumor, benign hyperplastic epithelium, stroma, and dilated cystic glands. The proportions of these cell types were then linkedin silicoto gene expression levels determined by microarray analysis, revealing unique cell-specific profiles. Gene expression differences for malignant and nonmalignant epithelial cells (tumor versus benign hyperplastic epithelium) could be identified without being confounded by contributions from stroma that dominate many samples or sacrificing possible paracrine influences. Cell-specific expression of selected genes was validated by immunohistochemistry and quantitative PCR. The results provide patterns of gene expression for these three lineages with relevance to pathogenetic, diagnostic, and therapeutic considerations.