bluuebunny/crossref_metadata_2025 huggingface dataset:
Special needs of adolescent and young women in accessing reproductive health: Promoting partnerships between young people and health care providers
Authors: Hobcraft G. , Baker T.
Published: July 2006

This article considers the unique challenges and opportunities that health care providers (HCPs) face when they address the sexual and reproductive health and rights of young women accessing services. Some of the difficulties that HCPs encounter in their work are highlighted, including poor remuneration, the impact of their personal biases and the effect of an under‐equipped working environment. The financial, logistical and emotional challenges young people face in accessing services are also described, as well as some small changes that could promote fruitful partnerships between HCPs and their young clientele. Also considered is how international documents concerning reproductive health can be utilized as advocacy tools to ensure that, when governments speak of making young people's needs a priority, resources are also made a priority—so that reproductive health can become a reality for all young people.
Inhibitory activity of bovine milk osteopontin and its fragments on the formation of calcium phosphate precipitates
Authors: Kumura Haruto , Minato Natsuko , Shimazaki Kei-ichi
Published: July 2006

Osteopontin (OPN) is an acidic phosphorylated glycoprotein found in many tissues and physiological fluids. OPN is known to possess multiple biological functions including bone remodeling, cell adhesion, cellular transformation and immunological mediation; these functions have been extensively reviewed (Butler et al. 1996; Sodek et al. 2000).
A survey of undergraduate otolaryngology experience at Newcastle University Medical School
Authors: Doshi J , Carrie S
Published: July 2006

Introduction: Due to the ‘modernizing medical careers’ changes, doctors with a firm career intention will be able to enter a speciality-specific training programme after their foundation years.

Materials and methods: A questionnaire was emailed to all 204 final year medical students at Newcastle Medical School asking about their ENT undergraduate experience and if they felt it was sufficient to consider a career in otolaryngology.

Results: One hundred and forty-four completed questionnaires (71 per cent) were returned, with respondents giving the following information: 54 per cent had had a formal ENT attachment (average seven and a half days); 24/144 (17 per cent) and 60/144 (42 per cent) respectively had not attended ENT clinic or theatre; less than 50 per cent had seen common ENT operations; 12/144 (8 per cent) had never heard of a septoplasty; two-thirds (24/36) of aspiring general practitioners had never seen a tonsillectomy or grommet insertion; and only 6/30 (20 per cent) of aspiring surgeons felt their ENT experience had been enough to consider the speciality as a career.

Discussion: Alternative methods of delivering an otolaryngology curriculum should be considered. We must promote otolaryngology to medical students at every opportunity.
Complications of keratosis obturans
Authors: Saunders N C , Malhotra R , Biggs N , Fagan P A
Published: July 2006

Three patients with extensive keratosis obturans were treated during a 12-month period. One presented with an idiopathic sensorineural hearing loss and was found to have keratosis obturans in the contralateral, asymptomatic ear. The disease process had resulted in a horizontal semicircular canal fistula in what was now, effectively, the only hearing ear. The second patient had an extensive dehiscence of the tegmen tympani. The third presented with a facial palsy. An automastoidectomy cavity was present, with circumferential skeletonization of the descending facial nerve over a length of 1.5 cm and dehiscence of the temporomandibular joint and jugular bulb. All three patients were successfully treated by surgical formalization of their automastoidectomy cavities. They appeared to represent cases of keratosis obturans rather than external auditory canal cholesteatoma, on the basis of previously published reports.

These complications and patterns of bone erosion have not previously been described in keratosis obturans. The third patient is believed to have the most extensive case of keratosis obturans yet described.
Genotypes of hepatitis C virus (HCV) among positive Lebanese patients: comparison of data with that from other Middle Eastern countries
Authors: SHARARA A. I. , RAMIA S. , RAMLAWI F. , FARES J. EID , KLAYME S. , NAMAN R.
Published: July 2006

Recently we identified hepatitis C virus (HCV) genotype 4 as the principle genotype among Lebanese thalassaemics. In an attempt to confirm the predominance of genotype 4 in Lebanon and perhaps in the Middle East, genotyping was attempted on 142 HCV-infected Lebanese patients from five different hospitals in the country. These included 38 HCV-positive patients with symptomatic liver disease who were referred to gastroenterologists and 104 HCV-positive patients with no symptoms of liver disease: 27 patients with thalassaemia, 30 patients on haemodialysis, 32 multi-transfused and 15 intravenous drug users. HCV genotyping was performed on PCR HCV RNA-positive samples using a commercial line probe assay (LiPA; Innogenetics, Ghent, Belgium). HCV genotype 4 is found to be the predominant genotype among HCV-infected Lebanese patients (ranging from 34·2% to 53·3%) followed by 1a (ranging from 12·5% to 43·3%) and 1b (ranging from 8·0% to 34·4%). In patients with symptomatic liver disease, however, genotype 4 (34·2%) was preceded by genotype 1a (39·5%). The predominance of HCV genotype 4 in our population (45·7%) confirms the predominance of HCV genotype 4 in Lebanon and most of the Arab countries in the Middle East but contrasts with data reported from non-Arab Middle Eastern Countries as can be seen from the literature review. Implications of genotyping for clinical outcome of HCV infection, response to treatment as well as for vaccine development are discussed.
Marked decrease in the incidence and prevalence of hepatitis A in the Basque Country, Spain, 1986–2004
Authors: CILLA G. , PÉREZ-TRALLERO E. , ARTIEDA J. , SERRANO-BENGOECHEA E. , MONTES M. , VICENTE D.
Published: July 2006

The aim of this study was to determine changes in the epidemiology of hepatitis A virus (HAV) infection in the Basque Country, Spain, and to evaluate their implications for vaccination strategies. A total of 1356 persons were enrolled in a study of the prevalence of anti-HAV in 2004 and compared with two previous studies (1986–1987 and 1992). The selection method and the characteristics of the population were similar in the three studies. A marked decline in the seroprevalence in all age groups (P<0·001) and in the incidence of cases/100000 inhabitants (from 38·0 in 1986–1988 to 2·9 in 2002–2004) were observed. The mean age of patients with hepatitis A increased from 17·7 years in 1986–1992 to 21·2 years in 1993–1998 and 25·3 years in 1999–2004 (P<0·001). Between 1997 and 2004, 20% of patients were hospitalized. The changes observed have occurred rapidly causing a change in the epidemiological pattern from middle-high endemicity (1986) to low endemicity (2004).
Separated by an ‘Ideological Chasm’: The Spanish National Labour Confederation and Bolshevik Internationalism, 1917–1922
Authors: GARNER JASON
Published: July 2006

This article covers the relationship between the National Labour Confederation of Spain and the Comintern and its union adjunct the Profintern, from the Confederation's initial support for the October Revolution to its subsequent outright rejection of communist politics, with reference to the positions adopted by revolutionary syndicalist movements in other countries. During this period a small number of individuals attempted to tie the Confederation to the Communist International, but failed. The article covers an important period in Spanish labour history, and helps to explain the mistrust that would bedevil the Spanish revolutionary working-class movement until the Civil War. Previous research has presented the battle for control of the CNT as a straightforward battle between anarchists and communists. This was not the case. The pro-communists were a miniscule faction, led by men recently affiliated to the CNT and who had no understanding of the depth of rejection of politics by Confederal militants. They only managed to take control of the national committee by chance. Aware of their weakness they were forced to act in a secretive and often underhand manner. Using material not consulted in previous studies this article shows the extent of their subterfuge and of the opposition this created in the Confederation, as well as demonstrating that the CNT was not the only revolutionary organisation to reject the Bolshevik International.
Insurance and Civil Society: Elements of an Ambivalent Relationship
Authors: LENGWILER MARTIN
Published: July 2006

This article examines the history of the relationship between insurance and civil society in the nineteenth and twentieth centuries. It tests the conventional narrative that this relationship followed an anticlimactic course, marked by the burgeoning of self-organised mutual societies in the nineteenth century and the decline and marginalisation of this sector of civil society owing to the rise of corporate insurance companies and statutory social insurance in the twentieth century. The article offers first a comparative analysis of nineteenth-century mutual insurance in different European countries (Britain, Germany, France and Switzerland), calling attention to limitations to the democratic and self-organised character of mutual associations. The second part of the article concentrates on a case study of twentieth-century corporate insurance in Switzerland, examining how life insurance companies dealt with customers and their personal data. The study indicates that insurance corporations adopted norms of extended privacy protection in the 1980s, a process that reflected new legal demands, customer claims and policies of civil rights organisations. The conclusion summarises the contradictory effects of insurance on the history of civil society and discusses the implications for the concept of civil society.
Zur Kommunikation zwischen praktizierenden und begutachtenden Ärzten
Authors: Adler
Published: July 2006

Praktizierende Ärzte haben häufig Mühe bei Begutachter- und Vertrauensärzten Verständnis für Patienten zu finden, die schwer leiden, aber an keiner klassischen psychiatrischen oder somatischen Störung erkrankt sind. Anhand eines Falls einer schwer kranken Frau, die nach zwei Eingriffen wegen Karzinomen sowohl von begutachtenden Psychiatern als auch Somatikern als gesund erklärt wird, wird dies erläutert. Der Einfluss des Wissenschaftsparadigmas des 17. Jahrhunderts auf die Auffassung von Krankheit wird skizziert; was harte und weiche Daten sind, wird erläutert; und die Entwicklung der Auffassung, was Krankheit ist, durch die Entstehung einer modernen biopsychosozialen Theorie der Medizin wird dargelegt. Die zwei Gesichter der medizinischen Evidenz und ihre Bedeutung für die Auffassung vom Krankheitswert werden erklärt. Empfehlungen für den Umgang des praktizierenden Arztes mit Begutachter- und Vertrauensärzten und Versicherungsträgern werden abgeleitet.
Zu Defiziten und möglichen Weiterentwicklungen aktueller Theorien der Lernmotivation
Authors: Fries Stefan
Published: July 2006

Zusammenfassung. Ausgehend von zwei Theoriebeiträgen zum Thema Lernmotivation ( Hofer, 2004 ; Krapp, 2004 ) wird ein Systematisierungsversuch motivationspsychologischer Theorien vorgestellt. Durch die Anwendung der Klassifikationsdimensionen Inhaltstheorien vs. Regulationstheorien, Kognition vs. Affekt und statische vs. dynamische Motivationssysteme auf die Theorienbildung in der Lernmotivationsforschung werden verschiedene Defizite, aber auch Möglichkeiten der Weiterentwicklung deutlich. Es wird herausgearbeitet, dass Theorien der Lernmotivation Regulationsprozesse stärker als bisher thematisieren sollten. Dabei verdienen insbesondere affektive und automatische kognitive Prozesse mehr Beachtung. Auch die Tatsache, dass lernmotiviertes Verhalten notwendigerweise in eine Dynamik von sich ständig ändernden und sich wechselseitig beeinflussenden motivationalen Tendenzen und Handlungsgelegenheiten eingebettet ist, sollte Eingang in die Theorienentwicklung finden.
Analyse von Lernumwelten
Authors: Lüdtke Oliver , Trautwein Ulrich , Kunter Mareike , Baumert Jürgen
Published: July 2006

Zusammenfassung. In der pädagogisch-psychologischen Forschung zur Unterrichtsqualität wird häufig auf Schülerurteile zurückgegriffen. Diese werden über die Schüler einer Klasse gemittelt, wenn ein Maß für die geteilte schulische Umwelt (z. B. Unterrichtsqualität) gebildet werden soll, das sich in Beziehung zu anderen Konstrukten (z. B. Schulleistung, Schulform) setzen lässt. Oft bleibt dabei unberücksichtigt, inwiefern die Schüler einer Klasse in ihren Wahrnehmungen der schulischen Umwelt tatsächlich übereinstimmen und wie reliabel die aggregierten Schülerwahrnehmungen sind. In diesem Beitrag werden Verfahren aus der Organisationspsychologie aufgegriffen, um die Reliabilität und Übereinstimmung von Schülerwahrnehmungen zu bestimmen. Anhand einer Reihe von Skalen zur Unterrichtswahrnehmung aus der TIMS-Studie (N = 2064 Schüler in 100 Klassen) wird die Anwendung der vorgestellten Indizes veranschaulicht. Abschließend wird die Fruchtbarkeit dieser Indizes für die Analyse von Mehrebenenstrukturen diskutiert, und es werden Empfehlungen für die Forschungspraxis gegeben.
Umstellung von einem unretardierten auf ein retardiertes Methylphenidatpräparat: Eine multizentrische, offene Studie an Kindern mit ADHS
Authors: Heger Steffen , Trott Götz-Erik , Meusers Michael , Schulz Eberhard , Rothenberger Aribert , Rettig Klaus , Medori Rossella , Schreiner Andreas , Remschmidt als Vertreter der deutschen C-2000-045-Studiengru Helmut
Published: July 2006

Zusammenfassung: Fragestellung: Untersuchung der Wirksamkeit und Verträglichkeit einer Umstellung auf OROS®-Methylphenidat (OROS®-MPH, Concerta®) bei Kindern und Jugendlichen mit ADHS. Methodik: Prospektive, multizentrische, offene Studie über 3 Wochen mit 213 Kinder mit ADHS im Alter von 6 - 16 Jahren, die von einem kurzwirksamen MPH-Präparat auf OROS®-MPH einmal täglich in flexibler Dosierung umgestellt wurden. Primäre Studienendpunkte waren Veränderungen der klinischen Symptome, erhoben mittels der Subskala Unaufmerksamkeit/Hyperaktivität der IOWA Conners Rating Scale und die Beurteilung der globalen Wirksamkeit durch Eltern und Lehrer. Sicherheit und Verträglichkeit wurden durch Erfassung von unerwünschten Ereignissen ermittelt. Die Entwicklung von Gewicht, sowie Veränderungen von Schlafqualität und Appetit wurden beobachtet. Ergebnisse: Die Umstellung auf OROS®-MPH einmal täglich führte zu einer signifikant besseren Kontrolle der ADHS-Symptome in der Elterneinschätzung. Dagegen zeigten sich nach Beurteilung der Lehrer keine signifikanten Veränderungen zur vorherigen Therapie. Die globale Wirksamkeit wurde von den Lehrern in 55%, von den Eltern in 79% und von den Prüfärzten in 77% der Fälle als «gut» oder «hervorragend» angesehen. OROS®-MPH wurde gut vertragen. Häufigste unerwünschte Ereignisse (UE) waren Kopfschmerzen (8,9%) und Rhinopharyngitis (7,0%). Unerwartete UE wurden nicht beobachtet. Schlussfolgerungen: Die Umstellung von ADHS-Patienten, die zuvor stabil auf IR-MPH eingestellt waren, auf OROS®-MPH einmal täglich führte zu einer signifikanten Verbesserung der ADHS-Symptome nach Einschätzung der Eltern. In der Schule zeigte OROS®-MPH eine vergleichbare Wirkung wie die vorher durchgeführte Therapie.
Aerosol extinction in a remote continental region of the Iberian Peninsula during summer
Authors: Elias Thierry , Silva Ana Maria , Belo Nuno , Pereira Sergio , Formenti Paola , Helas Günter , Wagner Frank
Published: July 2006

Summer in Évora (38°34′N, 7°54′W), Portugal, is described in terms of aerosol properties of extinction of the solar radiation. We create a data set composed of (1) cloud‐screened half‐day averaged values of aerosol optical thickness (AOT) measured at 7 wavelengths by both a CIMEL Sun/sky‐photometer and a YES shadowband radiometer and (2) half day averaged values of aerosol scattering coefficient (ASC) measured at the surface level at two wavelengths by a TSI nephelometer. Spectral dependence of both AOT and ASC gives the column and the surface Ångström exponents, αC and αS, respectively. Measurements are acquired in both 2002 and 2003 summers. Back trajectories are computed. A statistical study of the data set provides thresholds in AOT and αC for a classification of the days. The classification is applied with success to the case study of the 2003 summer heat wave episode and is generalized to the whole data set. In 23% of the cases, the turbidity in Évora is very low, with AOT441 < 0.12 and AOT873 < 0.04. The air mass origin is the North Atlantic Ocean at 700 and 970 hPa. In 31% of the cases, the turbidity is high. Increase of AOT is due to forest fire emissions, originating in the Iberian Peninsula, with 0.30 < AOT441 < 1.10 and αC > 1.2, and to desert dust plumes transported from North Africa within 72 to 120 hours at 700 hPa, with 0.10 < AOT873 < 1.10 and 0.1 < αC < 1.0. The vertical profile is highly variable, and several cases of aerosol mixing in the column are identified. The duration of the aerosol episode during the 2003 summer heat wave is 16 days, which is exceptionally long.
A New Magnetic Resonance Imaging Method for Mapping the Cerebral Blood Volume Fraction: The Rapid Steady-State T1 Method
Authors: Perles-Barbacaru Adriana T , Lahrech Hana
Published: July 2006

This paper describes a new rapid steady-state T1 (RSS T1) method for mapping the cerebral blood volume fraction ( CBVf) by magnetic resonance imaging (MRI). The principle is based on a two-compartment model of the brain (intra- and extravascular), and the effects of paramagnetic contrast agents on the intravascular longitudinal relaxation time T1. Using appropriate parameters, an Inversion-Recovery-Fast-Low-Angle-Shot sequence acts like a low pass T1 filter, suppressing signals from tissues with T1≫ TR ( TR=repetition time). It was shown in vivo that, exceeding a particular contrast agent dose, the signal reaches its maximum (corresponding to the intravascular equilibrium magnetization), and is maintained for a duration related to the dose. Acquisitions during this steady state divided by an additional measure of the overall (intra- and extravascular) magnetization at thermal equilibrium provides the CBVf. Experiments were performed on healthy rats at 2.35 T using P760 (Gd3+—compound from Guerbet Laboratories) and Gd-DOTA. Because of its high longitudinal relaxivity, P760 is more convenient, and was used to show the feasibility of the method. The CBVf in different structures of the rat brain was compared. The average CBVf for the whole brain slice is 3.29%±0.69% ( n=15). The influence of transendothelial water exchange was quantified and transversal relaxation effects were found negligible in microvasculature. Finally, the sensitivity of the method to CBVf increases under hypercapnia was evaluated (1%/mm Hg PaCO2), demonstrating its potential for longitudinal studies and functional MRI. Clinical applications are feasible since equivalent results were obtained with Gd-DOTA.
Mobile dislocation density and strain relaxation rate evolution during InxGa1−xAs∕GaAs heteroepitaxy
Authors: Lynch C. , Chason E. , Beresford R.
Published: July 2006

The kinetics of dislocation-mediated strain relaxation have been investigated during InxGa1−xAs∕GaAs molecular beam epitaxy growth. We use in situ curvature measurement to determine the film stress as a function of time during deposition. The relaxation behavior includes a temperature dependent initial relaxation stage which partially relieves the misfit strain, followed by a rapid strain relaxation which commences at a temperature independent thickness and proceeds at a comparable rate at all temperatures studied. We discuss these observations in terms of the mobile dislocation density evolution and the dependence of the strain relaxation rate on the driving force and temperature.
Intra-valence band transitions in self-assembled InAs∕GaAs quantum dots studied using photocurrent spectroscopy
Authors: Zibik E. A. , Adawi A. M. , Wilson L. R. , Lemaître A. , Cockburn J. W. , Hopkinson M. , Hill G.
Published: July 2006

We present a polarization-dependent study of the intra-valence band photocurrent signal in p-type self-assembled InAs∕GaAs quantum dots (QDs). The observed transitions are found to be strongly polarized in the quantum dot plane and associated with hole transitions from the dot states to the wetting layer states. Photocurrent spectra from p-doped QD samples are compared with photocurrent spectra from identically grown n-type QD samples. At 10K, the magnitude of the photocurrent signal is found to be smaller for p-type QD samples, compared with n-type QD samples. However, the rapid growth of the signal with increasing temperature due to thermal activation of holes from the light hole wetting layer states results in a comparable photoresponse to the n-type QDs at 50K.
Propagation dynamics of a LaMnO3 laser ablation plume in an oxygen atmosphere
Authors: Amoruso Salvatore , Sambri Alessia , Wang Xuan
Published: July 2006

The effect of ambient gas on the expansion dynamics of the plasma plume generated by excimer laser ablation of a LaMnO3 target is investigated by using fast photography. The plume propagation in an oxygen environment is examined with pressure ranging from vacuum to a few millibars. Imaging analysis performed over a complete set of images of the plume emission, for each pressure, has allowed following the changes in the plume structure, the plume front dynamics and stopping length, as well as the variation of plume angular distribution as a function of time and pressure. Our experimental findings evidence a number of interesting effects occurring at various times of the expansion and at different pressure levels. At low pressure (<10−2mbar) the plume expands freely resembling the propagation in high vacuum condition. Then, at intermediate pressure levels (10−2–1mbar) spatial splitting of the plume, plume front oscillations, plume broadening and sharpening, and, finally, plume stopping are observed as a function of the expansion time. The plume stopping length and the asymptotic angular width of the plume as a function of the pressure are analyzed and discussed. The expansion dynamics of the plume front is examined by means of a theoretical description of plume evolution and shock-wave propagation, which considers distance-related pressure dimensionless variables, resulting in a fairly good agreement.
Recrystallization behavior in chiral sculptured thin films from silicon
Authors: Schubert E. , Fahlteich J. , Rauschenbach B. , Schubert M. , Lorenz M. , Grundmann M. , Wagner G.
Published: July 2006

Chiral sculptured thin films, which contain amorphous silicon screws with a fiberlike fine structure, were grown by ion-beam-assisted glancing-angle deposition at room temperature. The thin films were postgrowth annealed in the temperature range from 400to1000°C. Raman spectroscopy and transmission electron microscopy investigations performed before and after sample annealing reveal a recrystallization of silicon at temperatures above 800°C, with a persistence of the chiral structure geometry and fine structure. The Raman results are further discussed in terms of quantum confinement and coexisting phase effects.
Numerical analysis of coupled wedge plasmons in a structure of two metal wedges separated by a gap
Authors: Pile D. F. P. , Gramotnev D. K. , Haraguchi M. , Okamoto T. , Fukui M.
Published: July 2006

This paper presents the results of the numerical finite-difference time-domain analysis of a strongly localized antisymmetric plasmon, coupled across a nanogap between two identical metal wedges. Dispersion, dissipation, field structure, and existence conditions of such coupled wedge plasmons are determined and investigated on an example of the fundamental coupled mode. It is shown that in the general case there exist three critical wedge angles and a critical gap width (separation between the wedge tips). If the gap width is larger than the critical separation, then the antisymmetric wedge plasmons can exist only in the ranges between the first and the second critical angles, and between the third critical angle and 180°. If the gap width is smaller or equal to the critical separation, then the third and the second critical angles merge, leaving only one interval of wedge angles within which the antisymmetric coupled wedge plasmons can exist. The effect of rounded wedge tips is also investigated and is shown to be similar to that of different wedge angles. Feasibility of using these plasmons for the design of efficient subwavelength waveguides is discussed.
Printable polythiophene gas sensor array for low-cost electronic noses
Authors: Chang Josephine B. , Liu Vincent , Subramanian Vivek , Sivula Kevin , Luscombe Christine , Murphy Amanda , Liu Jinsong , Fréchet Jean M. J.
Published: July 2006

A route for generating arrays of printable polythiophene-based gas sensor materials suitable for low-cost manufacturing is demonstrated. Materials with complementary sensor responses are synthesized by incorporating functional groups into the molecule, either along the polymer backbone or as end-capping groups. Using these materials as printable sensor inks, a functional, integrated gas sensor array chip is fabricated using additive deposition techniques. The sensor array shows sensitivity to a range of volatile organic compounds down to concentrations of 10ppm. A three-terminal thin film transistor structure is used, allowing the extraction of multiple parameters that help to elucidate the mechanisms responsible for sensor response and the role of the functional groups in this response.
Monolithic integration of AlGaInP laser diodes on SiGe∕Si substrates by molecular beam epitaxy
Authors: Kwon O. , Boeckl J. J. , Lee M. L. , Pitera A. J. , Fitzgerald E. A. , Ringel S. A.
Published: July 2006

Room temperature operation of visible AlGaInP laser diodes epitaxially integrated on Si was demonstrated. Compressively strained laser heterostructures were grown by molecular beam epitaxy (MBE) on low dislocation density SiGe∕Si substrates, where the threading dislocation density of the top relaxed Ge layers was measured in the range of 2×106cm−2. A threshold current density of Jth∼1.65kA∕cm2 for the as-cleaved, gain-guided AlGaInP laser grown on SiGe∕Si was obtained at the peak emission wavelength of 680nm under pulsed mode current injection. These results show that not only can high quality AlGaInP materials grown by MBE be achieved on Si via relaxed SiGe interlayers, but the prototype demonstration of laser diode operation on Si illustrates that very defect sensitive optoelectronics in the III-P system can indeed be integrated with Si substrates by heteroepitaxial methods.
The role of geometry in the friction generated on the colonic surface by mucoadhesive films
Authors: Dodou Dimitra , Breedveld Paul , Wieringa Peter A.
Published: July 2006

One of the main challenges in designing diagnostic devices able to move along the colon is their locomotion method. Generating friction without applying high normal forces is a key requirement in order to eliminate the risk of tissue damage. One possible solution is to generate friction by means of adhesive forces. For this reason, the device can be covered with mucoadhesive films, which are able to stick on the colonic surface. This paper identifies that the friction of mucoadhesive films depends strongly on their geometry. It seems therefore feasible to adapt the level of the friction to the properties of the colonic surface by altering the geometry of the films covering the device. Moreover, an eventual influence of the film geometry on the generated friction can reveal film shapes which create high grip despite their small size, leading to a decrease in the overall size of the device. The aim of the paper is to test in vitro the relationship between film geometry and generated friction, to fit the experimental findings in a simplified but generic macroscopic theoretical model able to predict the behavior of various geometries, and to embed those findings in the principles of the design implementation.
Electrical and optical properties of ZnO thin films grown on Si substrates
Authors: Yuldashev Sh. U. , Panin G. N. , Kang T. W. , Nusretov R. A. , Khvan I. V.
Published: July 2006

Undoped and nitrogen doped ZnO films were deposited on Si substrates by ultrasonic spray pyrolysis at ambient atmosphere. The p type of conductivity for the nitrogen doped ZnO films has been observed. The concentration of free holes in ZnO films has been found to depend strongly on the resistivity of Si substrate. With decreasing of the substrate resistivity the concentration of free holes in ZnO films increases. The hole concentration of 1.1×1018cm−3 and the hole mobility of 24cm2V−1s−1 were observed in the ZnO films grown on the Si substrates with the resistivity of 0.001Ωcm.
Source of 1∕f noise in carbon nanotube devices
Authors: Briman Mikhail , Bradley Keith , Gruner George
Published: July 2006

We report the observation of 1∕f noise in carbon nanotube field-effect transistors as a function of gate potential. In order to avoid additional low frequency noise contribution from SiO2-nanotube interactions, the measurements were carried out in conducting liquid. Based on the experimental results, we conclude that the number of carrier fluctuations is the source of the 1∕f noise.
Structural and optical properties of Si∕SiO2 superlattices prepared by low pressure chemical vapor deposition
Authors: Yu Zhenrui , Aceves-Mijares Mariano , Quiroga Enrique , Lopez-Estopier R. , Carrillo Jesus , Falcony Ciro
Published: July 2006

Si ∕ Si O 2 superlattices (SLs) structures were prepared using a low-pressure chemical vapor deposition (LPCVD) method. The structural and optical properties of the SLs materials were characterized using atomic force microscopy (AFM), Fourier transformed infrared (FTIR) absorption, x-ray diffraction, and room-temperature photoluminescence (PL) measurements. The AFM results show that a periodically layered Si∕SiO2 structure was successfully deposited with nanometer-sized Si dots embedded in the Si layers. The FTIR spectra show that the SiO2 near the Si∕SiO2 interface is more ordered than the amorphous SiO2 in the center of the SiO2 layers. The Si∕SiO2 SLs films show a room-temperature PL in the visible-near infrared wavelength region. The PL intensity is significantly enhanced by a high-temperature annealing at 1100°C. The peak position and intensity of the main emission band in the PL spectra strongly depend on the Si layer thickness. A pronounced redshift with increasing Si layer thickness is observed. This emission peak position can be fitted by the theory of quantum confinement effect in Si dots. The emission from recombination through defect and interface states was also observed in the SLs films.
Phase transformations induced by spherical indentation in ion-implanted amorphous silicon
Authors: Haberl B. , Bradby J. E. , Ruffell S. , Williams J. S. , Munroe P.
Published: July 2006

The deformation behavior of ion-implanted (unrelaxed) and annealed ion-implanted (relaxed) amorphous silicon (a-Si) under spherical indentation at room temperature has been investigated. It has been found that the mode of deformation depends critically on both the preparation of the amorphous film and the scale of the mechanical deformation. Ex situ measurements, such as Raman microspectroscopy and cross-sectional transmission electron microscopy, as well as in situ electrical measurements reveal the occurrence of phase transformations in all relaxed a-Si films. The preferred deformation mode of unrelaxed a-Si is plastic flow, only under certain high load conditions can this state of a-Si be forced to transform. In situ electrical measurements have revealed more detail of the transformation process during both loading and unloading. We have used ELASTICA simulations to obtain estimates of the depth of the metallic phase as a function of load, and good agreement is found with the experiment. On unloading, a clear change in electrical conductivity is observed to correlate with a “pop-out” event on load versus penetration curves.
Superhigh strength and excellent soft-magnetic properties of [(Co1−xFex)0.75B0.2Si0.05]96Nb4 bulk glassy alloys
Authors: Shen Baolong , Chang Chuntao , Kubota Takeshi , Inoue Akihisa
Published: July 2006

Bulk glassy alloys of [(Co1−xFex)0.75B0.2Si0.05]96Nb4 with diameters up to 4mm were synthesized in the composition range of x=0.1–0.4. In addition to high glass-forming ability, the bulk glassy alloys exhibit superhigh fracture strength of 3980–4170MPa and Young’s modulus of 190–210GPa, as well as excellent soft-magnetic properties, i.e., rather high saturation magnetization of 0.71–0.97T, low coercive force of 0.7–1.8A∕m, high permeability of (1.48–3.25)×104, and extremely low saturation magnetostriction of (0.55–5.76)×10−6. The mechanisms for the high glass-forming ability, superhigh strength, and excellent soft-magnetic properties of the Co-based bulk glassy alloys are discussed.
Phonon and vibrational spectra of hydrogenated CdTe
Authors: Polit J. , Sheregii E. M. , Cebulski J. , Robouch B. V. , Marcelli A. , Cestelli Guidi M. , Piccinini M. , Kisiel A. , Zajdel P. , Burattini E. , Mycielski A.
Published: July 2006

This work presents far-infrared reflectivity spectra collected with synchrotron radiation on specially prepared CdTe monocrystals in the temperature region of 30–300K. The investigated samples were of three different types characterized by the three different levels of hydrogenation—strong, middle, and low ones. In order to interpret the experimental data, the imaginary part of the dielectric function was evaluated by means of Kramers-Kronig transformation. To determine quantitatively the influence of hydrogen atoms on the phonon and vibrational spectra of hydrogenated CdTe crystals we used the special statistical model proposed in this paper. This model takes into account the tetrahedron as the basic structural unit and distinguishes the contribution of the hydrogen-bearing tetrahedra from the contribution of the hydrogen-free ones to the crystal phonon spectra.
Space charge limited flow in a rectangular region: Profile of the current density
Authors: Rokhlenko A.
Published: July 2006

A careful analysis of boundary conditions imposed by the infinite cathode emissivity and infinitely strong magnetic field (or a physical boundary of the current region) allows us to determine the shape of the current density (its leading term) near the margin of the space charge. The current density can go to zero at the flow edge or be singular depending on the geometry of the system. In the latter case the so called “current wings” become sensitive to the strength of the magnetic field. A simple modification of the emitter geometry can provide an almost flat current profile. Implications for treating experimental measurements, design of high current devices, and particle beam extraction are discussed.
Observation of hydrogen in deuterated methane hydrate by maximum entropy method with neutron powder diffraction
Authors: Hoshikawa Akinori , Igawa Naoki , Yamauchi Hiroki , Ishii Yoshinobu
Published: July 2006

The crystal structure of deuterated methane hydrate (structure I, space group: Pm3¯n) was investigated by neutron powder diffraction at temperatures of 7.7–185K. The scattering amplitude density distribution was examined by a combination of Rietveld method and maximum entropy method (MEM). The distribution of the D atoms in both D2O and CD4 molecules was clarified from three-dimensional graphic images of the scattering amplitude density. The MEM results showed that there were low-density sites for the D atom of D2O in a particular location within the D2O cage at low temperatures. The MEM provided more reasonable results because of the decrease in the R factor that is attainable by this method. Accordingly, the low-density sites for the D atom of D2O probably exist within the D2O cage. This suggests that a spatial disorder of the D atom of D2O occurs at these sites and that hydrogen bonds between D2O molecules become partially weakened. With regard to the CD4 molecules, there were high-density sites for the D atom of CD4, and the density distribution of the C and D atoms was observed separately in the scattering amplitude density image. Consequently, the C–D bonds of CD4 were not observed clearly because the CD4 molecules had an orientational disorder. The D atoms of CD4 were displaced from the line between the C and O atoms, and were located near the face center of the polygon in the cage. Accordingly, the D atoms of CD4 were not bonded to specific O atoms. This result is consistent with the hydrophobicity of the CD4 molecule. We also report the difference between the small and the large cages in the density distribution map and the temperature dependence of the scattering amplitude density.
Distributions of self-trapped hole continuums in silica glass
Authors: Wang R. P. , Saito K. , Ikushima A. J.
Published: July 2006

Photobleaching of self-trapped holes (STH) in low temperature UV-irradiated silica glass has been investigated by the electron spin resonance method. The bleaching time dependence of the decay of two kinds of STH, STH1, and STH2, could be well fitted by the stretched exponential function, and STH2 has a quicker decay than STH1. On the other hand, the decay becomes significant large when the photon energy increases from 1.5to2.0eV, and then keeps constant with a further increase of photon energy. The distributions of the STH continuums are estimated at the positions on top of the valence band, being 1.66±0.27eV for STH1 and 1.63±0.33eV for STH2. A possible recombination mechanism is proposed to explain the decay of STH signals.
Optical properties of tetragonal ferroelectric single crystal lead magnesium niobate lead titanate
Authors: He Chongjun , Luo Laihui , Zhao Xiangyong , Xu Haiqing , Zhang Xuehua , He Tianhou , Luo Haosu , Zhou Zhongxiang
Published: July 2006

The comprehensive optical properties were characterized for tetragonal ferroelectric single crystal 0.65Pb(Mg1∕3Nb2∕3)O3–0.35PbTiO3. The refractive indices were measured using minimum deviation method at different wavelengths, and the dispersion equations were determined for both ordinary and extraordinary rays. Transparent spectrum of the crystal ranges from 450 to more than 2500nm, and the poling process could enhance the transparency dramatically. By the Senarmont compensator method, the effective electro-optic coefficient at 514.5nm wavelength was obtained, γc=93.9pm∕V. These results show that the tetragonal lead magnesium niobate lead titanate single crystals are very promising candidate for a wide range of practical optical devices.
System for measuring auto- and cross correlation of current noise at low temperatures
Authors: DiCarlo L. , Zhang Y. , McClure D. T. , Marcus C. M. , Pfeiffer L. N. , West K. W.
Published: July 2006

We describe the construction and operation of a two-channel noise detection system for measuring power and cross spectral densities of current fluctuations near 2MHz in electronic devices at low temperatures. The system employs cryogenic amplification and fast Fourier transform based spectral measurement. The gain and electron temperature are calibrated using Johnson noise thermometry. Full shot noise of 100pA can be resolved with an integration time of 10s. We report a demonstration measurement of bias-dependent current noise in a gate defined GaAs∕AlGaAs quantum point contact.
Influence of composition and order on the magnetism of Fe–Pt alloys: Neutron powder diffraction and theory
Authors: Lyubina Julia , Opahle Ingo , Richter Manuel , Gutfleisch Oliver , Müller Karl-Hartmut , Schultz Ludwig , Isnard Olivier
Published: July 2006

The dependence of the magnetic moments on the compositional order in Fe–Pt alloys was studied by neutron powder diffraction. For alloys with almost perfect L10-type long-range order the experimental value of the Fe magnetic moment was determined to be 2.8±0.1μB (extrapolated to zero temperature). Combined analysis of experimental and density functional data shows that the Fe moment drops with increasing Fe content, but is less sensitive to the degree of order, in contrast to the well-known behavior of Fe–Al alloys.
Comparison of electrical and chemical characteristics of ultrathin HfON versus HfSiON dielectrics
Authors: Pant G. , Gnade A. , Kim M. J. , Wallace R. M. , Gnade B. E. , Quevedo-Lopez M. A. , Kirsch P. D. , Krishnan S.
Published: July 2006

The electrical and chemical properties of ultrathin HfON and HfSiON gate dielectrics are investigated as a function of physical thickness. Grazing incidence x-ray diffraction was used to detect phase separation and crystallization of 1.5, 2.0, 2.5, and 4.0nm films of HfON and HfSiON after a 1000°C-10s activation annealing. X-ray photoelectron spectroscopy was used to determine the chemical composition of the dielectrics. No evidence of crystallization was detected in 1.5nm HfON or HfSiON films after the activation annealing. The HfON film showed crystallization at a 2.0nm thickness whereas the 2.0nm HfSiON film remained amorphous.
Room temperature bonding of silicon and lithium niobate
Authors: Howlader M. M. R. , Suga T. , Kim M. J.
Published: July 2006

The feasibility of wafer-level bonding was examined for silicon (Si)/lithium niobate (LiNbO3) wafers by using a modified surface activated bonding process at room temperature. A low energy argon ion source of 80eV energy with 3A current was used, which was capable of sputter cleaning and depositing Fe nanolayers on the surfaces. Visual inspection showed that almost all of the 4in. Si∕LiNbO3 wafers were bonded. The measured bond strengths were as high as 37MPa but were inhomogeneous. This is due to the lack of uniform application of force over the surfaces (which are not parallel to the jigs) and the pulling angles during the pulling test. A 5nm thick amorphous layer was observed across the Si∕LiNbO3 interface. Electron energy loss spectroscopy analysis confirmed the presence of Fe in the interfacial amorphous layer. This Fe-containing interfacial layer appears to be responsible for the high bonding strength observed between Si∕LiNbO3 at room temperature.
Information Concentration along the Boundary Contours of Naturally Shaped Solid Objects
Authors: Norman J Farley , Phillips Flip , Ross Heather E
Published: July 2006

In this study of the informativeness of boundary contours for the perception of natural object shape, observers viewed shadows/silhouettes cast by natural solid objects and were required to adjust the positions of a set of 10 points so that the resulting dotted shape resembled the shape of the original silhouette as closely as possible. For each object, the observers were then asked to indicate the corresponding positions of the 10 points on the original boundary contour. The results showed that there was a close correspondence between the chosen positions of the points and the locations along the boundary contour that were local curvature maxima (convexities or concavities). This finding differs from that of Kennedy and Domander (1985 Perception14 367–370), and shows that, at least for natural objects, the original hypothesis of Attneave (1954 Psychological Review61 183–193) is valid—local curvature maxima are indeed important for the perception of shape.
Transfer of NKG2D and MICB at the cytotoxic NK cell immune synapse correlates with a reduction in NK cell cytotoxic function
Authors: Roda-Navarro Pedro , Vales-Gomez Mar , Chisholm Susan E. , Reyburn Hugh T.
Published: July 2006

Although transfer of membrane proteins has been shown to occur during immune cell interactions, the functional significance of this process is not well understood. Here we describe the intercellular transfer of NKG2D and MHC class I chain-related molecule (MIC) B proteins at the cytotoxic natural killer cell immune synapse (cNK-IS). MICB expressed on the 721.221 cell line induced clustering of NKG2D at the central supramolecular activation cluster, surrounded by a peripheral supramolecular activation cluster containing F-actin. Moreover, natural killer (NK) cell membrane-connective structures formed during cytotoxic interactions contained F-actin, perforin, and NKG2D. NKG2D transfer depended on binding to MICB and was specific because transfer of other molecules not involved in NK-IS formation was not observed. Transfer of MICB to NK cells also was noted, suggesting a bidirectional exchange of receptor/ligand pairs at cNK-IS. Experiments designed to test the functional significance of these observations revealed that brief interactions between NK cells and MICB expressing target cells led to a reduction in NKG2D-dependent NK cytotoxicity. These data demonstrate interchange of an activating receptor and its ligand at the cNK-IS and document a correlation between synapse organization, intercellular protein transfer, and compromised NK cell function after interaction with a susceptible target cell.
Barttin modulates trafficking and function of ClC-K channels
Authors: Scholl Ute , Hebeisen Simon , Janssen Audrey G. H. , Müller-Newen Gerhard , Alekov Alexi , Fahlke Christoph
Published: July 2006

Barttin is an accessory subunit of a subgroup of ClC-type chloride channels expressed in renal and inner ear epithelia. In this study, we examined the effects of barttin on two ClC-K channel isoforms, rat ClC-K1 and human ClC-Kb, using heterologous expression, patch clamping, confocal imaging, and flow cytometry. In the absence of barttin, only a small percentage of rClC-K1 and hClC-Kb channels are inserted into the plasma membrane. Coexpression of barttin enhances surface membrane insertion and furthermore modifies permeation and gating of ClC-K channels. hClC-Kb channels are nonfunctional without barttin and require the coexpressed accessory subunit to become anion conducting. In contrast, rClC-K1 channels are active without barttin, but at the cost of reduced unitary conductance as well as altered voltage dependence of activation. We mapped the separate functions of barttin to structural domains by a deletion analysis. Whereas the transmembrane core is necessary and sufficient to promote ClC-K channel exit from the endoplasmic reticulum, a short cytoplasmic segment following the second transmembrane helix modifies the unitary conductance. The entire cytoplasmic carboxyl terminus affects the open probability of ClC-K channels. The multiple functions of barttin might be necessary for a tight adjustment of epithelial Cl
−
conductances to ensure a precise regulation of body salt content and endocochlear potential.