bluuebunny/crossref_metadata_2025 huggingface dataset:
Recrystallization of cold‐worked gold during α‐irradiation
Authors: Beyer H. , Sizmann R.
Published: March 2011

The recrystallization of gold is investigated by electrical resistivity measurements and checked with photomicographs. The influence of irradiation with 4 Me V α‐particles at different temperatures and flux densities is studied. Between 100 to 150°C the recrystallization of Au (purity 99.96%) is enhanced during irradiation. With increasing irradiation dose the enhanced reaction rate is overcompensated by a strong retardation of the grain growth. The enhancement is attributed to radiation‐induced diffusion, the retardation to barrier pinning of dislocations, and grain boundaries.
Zinc‐blende (cubic) GaN bulk crystals grown by molecular beam epitaxy
Authors: Novikov S. V. , Foxon C. T. , Kent A. J.
Published: March 2011

We have studied the growth of zinc‐blende (cubic) GaN and AlxGa1‐xN layers and bulk crystals by molecular beam epitaxy (MBE). MBE is normally regarded as an epitaxial technique for the growth of very thin layers with monolayer control of their thickness. However, we have used the MBE technique for bulk crystal growth and have produced GaN layers up to 100 μm in thickness. Thick, cubic GaN films were grown on semi‐insulating GaAs (001) substrates by a modified plasma‐assisted molecular beam epitaxy (PA‐MBE) and were removed from the substrate after the growth. The resulting free‐standing GaN wafers with thicknesses in the 30–100 μm range may be used as substrates for further epitaxy of cubic GaN‐based structures and devices. We have demonstrated the scalability of the process by growing GaN layers up to 3” in diameter. We have developed procedures to cleave the wafers and to polish them to produce epi‐ready surfaces. We have demonstrated that the PA‐MBE process we have developed also allows us to achieve free‐standing zinc‐blende AlxGa1‐xN wafers over the entire composition range from GaN to nearly pure AlN. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InGaN based light emitting diodes utilizing Ga doped ZnO as a highly transparent contact to p‐GaN
Authors: Liu H. Y. , Li X. , Liu S. , Ni X. , Wu M. , Avrutin V. , Izyumskaya N. , Özgür Ü. , Yankovich A. B. , Kvit A. V. , Voyles P. M. , Morkoç H.
Published: March 2011

We report on the electrical and optical properties of InGaN based light emitting diodes (LEDs) utilizing Ga doped ZnO (GZO) grown by MBE as a highly transparent contact p ‐electrode (GZO‐LEDs). For comparison, the LEDs with semi‐transparent thin Ni/Au (5nm/5nm) current spreading layers were also fabricated on the same wafer (Ni/Au‐LEDs). Pulsed electroluminescence measurements revealed that the relative external quantum efficiency (EQE) of the GZO‐LED is 1.7‐2 times higher than that of Ni/Au‐LED at high current densities. Moreover, GZO‐LEDs can withstand much higher current densities (4700 A/cm2) than the Ni/Au LEDs (3500 A/cm2) under pulsed mode. Unpackaged GZO‐LEDs with 200 μm diameter showed negligible light output degradation for up to 30 mins under CW current of 100 mA (corresponding to a 318 Acm‐2 current density), while the light output for Ni/Au‐LEDs was reduced by 85% after only 5 mins of operation due to the severe current crowding effect (or current filamentation). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Empirical potential approach to the epitaxial relationship between AlN thin films and Si(001) substrates
Authors: Ito Tomonori , Nakano Haruo , Akiyama Toru , Nakamura Kohji
Published: March 2011

Epitaixial relationship between AlN thin films and Si(001) substrates is systematically investigated using the empirical interatomic potential on the basis of the experimental findings for AlN on Si(001) grown by plasma‐assisted molecular beam epitaxy and reactive magnetron sputtering. The calculated results for the structural stability of AlN on Si(001) reveal that (0001)‐oriented 2H‐AlN becomes stable even on 3C‐Si(001) beyond the film thickness of six monolayers with epitaxial relationship of AlN〈01‐10〉‖Si[110]. This is consistent with the experimental results found in plasma‐assisted molecular beam epitaxy. We also estimate the relative appearance ratio among various rotational domains with AlN〈11‐20〉‖Si[110] (Type A) and AlN〈01‐10〉‖Si[100] (Type B) in addition to the AlN〈01‐10〉‖Si[110] (Type C). The calculated appearance ratio such as 23.7% (Type A), 30.7% (Type B), and 14.8% (Type C) are favourably compared with respective experimental results such as 24.7%, 26.5%, and 22.8% obtained by reactive magnetron sputtering. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scanning near‐field luminescence microscopy of green light emitting GaInN/GaN quantum wells grown on c‐plane sapphire and on c‐plane bulk GaN
Authors: Clodius P. , Jönen H. , Bremers H. , Rossow U. , Hangleiter A.
Published: March 2011

In contrast to blue and violet emitting GaInN quantum well structures grown on sapphire, which show a high internal quantum efficiency (IQE), green emitting structures suffer from relatively low efficiencies. Usually, the large internal polarization fields are made responsible for such reduced efficiencies. For quantum wells with high In content, however, the efficiencies are even lower than expected.

In this work we present the results of our near‐field optical investigations of the photoluminescence of green emitting GaInN quantum well structures grown on c‐plane sapphire and on bulk GaN substrates. Our aim is to clarify the influence of defects on the spatial structure of the luminescence of green emitting quantum wells. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarity control of AlN by poling in the crystal growth
Authors: Ota Yuichi , Inushima Takashi
Published: March 2011

We present a new technique for controlling the polarity of AlN grown by metal‐organic chemical vapor deposition on sapphire. We apply electric field along the c‐axis throughout the crystal growth process and Al‐ or N‐polarity AlN is obtained according to the direction of the electric field.

It turns out that the polarization of pyroelectric AlN can be changed by the external field applied at the initial growth stage. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calculation of phase diagrams of the Li3N‐Al system for AlN growth
Authors: Yayama Tomoe , Kangawa Yoshihiro , Kakimoto Koichi
Published: March 2011

To investigate the possibility of AlN synthesis from Li3N and Al as source materials, a phase diagram of the Li3N‐Al system was constructed by using calculation of the phase diagram (CALPHAD) method. Thermodynamic data of a ternary system was prepared on the basis of data of binary systems, which are Al‐Li, Al‐N and Li‐N. In the present work, we newly incorporated thermodynamic data of Li3AlN2 into the system. Gibbs energy function of Li3AlN2 is described by a stoichiometric compound model and the parameter was determined to reproduce our experimental results. The calculated phase diagram was verified by differential thermal analysis (DTA). The calculated solution temperature of Li3AlN2 agreed with the DTA results and the validity was confirmed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of sputtering conditions on crystalline quality of AlN layers deposited by RF reactive sputtering
Authors: Kumada Tomoyuki , Ohtsuka Makoto , Takada Kazuya , Fukuyama Hiroyuki
Published: March 2011

Aluminum nitride (AlN) is increasingly demanded for use in semiconductor‐related industries. This study was undertaken for fabrication of high‐quality AlN thick layers using radio‐frequency (RF) reactive sputtering with a pure Al target. The AlN layers were sputtered homoepitaxially on high‐quality thin AlN layers on sapphire substrates for 1.5 h with 300 to 650 W at 573 and 773 K. The AlN thin layers were grown using sapphire nitridation before sputtering. A N2‐Ar gas mixture was used as the sputtering atmosphere and N2 gas flow ratio was changed from 20 to 60 vol%N2. In all sputtering conditions c‐axis oriented AlN layers were fabricated. AlN layer sputtered with 400 W under 40 to 60 vol%N2 at 773 K was grown by about 1 μm thickness. The AlN layer sputtered with 400 W under 40 and 50 vol%N2 at 573 and 773 K showed superior quality, with almost identical crystal structural quality to that of each nitrided sapphire substrate. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reliability and performance of pseudomorphic ultraviolet light emitting diodes on bulk aluminum nitride substrates
Authors: Grandusky James R. , Gibb Shawn R. , Mendrick Mark , Schowalter Leo J.
Published: March 2011

High quality, bulk aluminum nitride substrates were used to obtain pseudomorphic AlxGa1‐xN layers with low dislocation density, smooth surfaces, and high conductivity. These layers were fabricated into mid‐ultraviolet light emitting diodes with peak wavelengths in the range of 240‐260 nm. From transmission electron microscope images, it was confirmed that the dislocation density in the n‐type Al0.7Ga0.3N layer is low with no dislocations in the field of view. The low dislocation density continued through the quantum wells and electron blocking layer. However, the lattice mismatch between the pseudomorphic AlxGa1‐xN layers and the p‐type GaN contact layer is high (approximately 2.4%) and the pseudomorphic growth could not be achieved for thick layers. Instead, a network of misfit dislocations was formed at the GaN/AlxGa1–xN interface, which relieved strain in the GaN layer. The threading dislocations did not appear to propagate into the active region and thus enable the achievement of high internal (IQE) and external quantum efficiencies (EQE) from the devices fabricated on low dislocation density pseudomorphic active layers. Values of EQE as high as 1.44% for a device emitting at 248 nm operated in pulsed mode were achieved. Devices were packaged in lead frame packages and achieved output powers of 45 mW at 1.5 A for a 257 nm device with a peak EQE of 0.8% at 200 mA when operated in pulsed mode. The thermal properties of the packaged devices limited high current performance in CW mode. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Epitaxial growth of β‐Si3N4 by the nitridation of Si with adsorbed N atoms for interface reaction epitaxy of double buffer AlN(0001)/β‐Si3N4/Si(111)
Authors: Yamabe Nobuhiko , Yamamoto Yuka , Ohachi Tadashi
Published: March 2011

A fabrication process of an interface reaction epitaxy (IRE) β‐Si3N4 and an IRE AlN were investigated to produce a double buffer layer (DBL) of AlN(0001)/β‐Si3N4/Si(111) for the growth of group III nitrides films on Si. The β‐Si3N4 was formed by using adsorbed (ADS) nitrogen atoms irradiated indirectly from a rf‐plasma cell. Two surface structures of the β‐Si3N4, which were “8 x 8” and “8/3 x 8/3” reconstructions, were fabricated by changing the nitrogen irradiation conditions; complete and incomplete nitridation of Si surface and successive heat treatment up to 875 °C formed the “8 x 8” and “8/3 x 8/3” structures, respectively. IRE AlN was grown by 1 monolayer of Al deposition on the β‐Si3N4 and successive annealing at 875 °C. Al and N polarity DBLs were grown on the “8 x 8” and “8/3 x 8/3” structures, respectively. These results indicated that the polarity of DBL could be controlled by the surface reconstruction of β‐Si3N4 (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tri‐halide vapor phase epitaxy of GaN using GaCl3 gas as a group III precursor
Authors: Yamane T. , Hanaoka K. , Murakami H. , Kumagai Y. , Koukitu A.
Published: March 2011

Tri‐halide vapor phase epitaxy (THVPE) of GaN using GaCl3 gas generated by the reaction between metallic Ga and Cl2 gas at the source zone was investigated. From thermodynamic analysis, it was predicted that the driving force for GaN growth by THVPE would be larger than that by conventional mono halide vapor phase epitaxy (HVPE) using GaCl as a group III precursor. From the growth experiments, it was shown that the growth rate of GaN by THVPE was much higher than that by conventional HVPE under the same input partial pressure conditions. It was also revealed that GaN growth is possible at higher temperatures by THVPE. In photoluminescence (PL) and X‐ray diffraction (XRD) measurements, a GaN layer grown by THVPE at 1150 °C has optical properties and crystalline quality superior to that of a GaN layer grown by HVPE at 970 °C (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular beam epitaxy based growth of cubic GaN quantum dots
Authors: Schupp T. , Meisch T. , Neuschl B. , Feneberg M. , Thonke K. , Lischka K. , As D. J.
Published: March 2011

Zinc‐blende GaN/AlN quantum dots were grown in a molecular beam epitaxy system by two alternative methods. In method A the quantum dots were formed by the Stranski‐Krastanov process, whereas in method B the quantum dots were created by a vapor‐liquid‐solid process, respectively. The density of the Stranski‐Krastanov quantum dots was adjustable in a range of 5 x 109 cm‐2 to 5 x 1012 cm‐2. The density of the quantum dots grown by method B was controllable in the range of 5 x 108 cm‐2 to 5 x 1012 cm‐2. For both methods the samples with a high density of quantum dots have shown strong optical activity in photoluminescence spectroscopy. The emission energy of the quantum dots was tuneable in a range of 3.5 eV to 3.9 eV by alteration of the quantum dot height. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Erratum Efficient solar energy conversion of TiO2 nanotubes produced by rapid breakdown anodization – a comparison [Phys. Status Solidi RRL 1, No. 4, 135–137 (2007)]
Authors: Hahn R. , Stergiopoulos T. , Macak J. M. , Tsoukleris D. , Albu S. P. , Kim D. , Ghicov A. , Kunze J. , Falaras P. , Schmuki P.
Published: March 2011

There is an error in the scale bar of the inset of Fig. 1b in the original manuscript. The corrected figure is presented here in Fig. 1. As the originally used figure (see Fig. 2a here) was not very representative for TiO2 nanotubes grown under the described conditions we now provide a more representative picture (Fig. 2b) confirming an average thickness of ∼2.5 µm (as given throughout the paper). No statement or other scientific content of the article is affected by this correction. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Examining the performance effects of post spin‐off links to parent firms: should the apron strings be cut?
Authors: Semadeni Matthew , Cannella Albert A.
Published: March 2011

Little research has examined the performance implications of the parent‐child relationship post spin‐off. Although the parent provided oversight of the child prior to the spin‐off, effects of post spin‐off links to the child remain unclear. Applying transaction cost and agency theories, our study of 142 firms spun‐off between 1986 and 1997 examines how oversight and ownership by the parent firm influence stock market performance post spin‐off. We find that while child firms benefit from some links to the parent, having too many links is negatively related to performance. The findings suggest that there is a balance between having too much parental involvement and not enough. Our study extends understanding of post spin‐off child firm performance and provides valuable insights for both parent and child firms. Copyright © 2011 John Wiley & Sons, Ltd.
Strategies for Patterning Biomolecules with Dip‐Pen Nanolithography
Authors: Wu Chien‐Ching , Reinhoudt David N. , Otto Cees , Subramaniam Vinod , Velders Aldrik H.
Published: March 2011

Dip‐pen nanolithography (DPN) is an atomic force microscopy (AFM)‐based lithography technique, which has the ability to fabricate patterns with a feature size down to approximately 15 nm using both top‐down and bottom‐up approaches. DPN utilizes the water meniscus formed between an AFM tip and a substrate to transfer ink molecules onto surfaces. A major application of this technique is the fabrication of micro‐ and nano‐arrays of patterned biomolecules. To achieve this goal, a variety of chemical approaches has been used. This review concisely describes the development of DPN in the past decade and presents the related chemical strategies that have been reported to fabricate biomolecular paterns with DPN at micrometer and nanometer scale, classified into direct‐ and indirect DPN methodologies, discussing tip‐functionalization strategies as well.
Analysis of Product Morphologies and Reaction Mechanisms on Gaseous Reduction of Iron Oxides
Authors: Hayes P. C.
Published: March 2011

It is well established that in gaseous reduction processes solid iron oxides exhibit a wide range of reducibilities. Using the interface stability criteria developed to describe the decomposition of metal compounds in reactive gas atmospheres, together with microstructural evidence obtained under well characterised reaction conditions, the relationships between product structures, and the mechanisms and the kinetics of reduction of iron oxides have been examined. It is shown that the structures and reaction rates can be explained through the occurrence of four principal mechanisms; continuous gas pore formation, dense metal layer growth, discontinuous metal layer breakdown and continuous coupled growth of metal and pores. Through identification of the critical conditions for these different mechanisms, the maximum rates of reduction of a given starting material as a function of temperature, thermal history and gas conditions can be more clearly understood.
Performance of proposed thin‐wire model in finite difference time domain method
Authors: Tanabe Kazuo
Published: March 2011

Thin‐wire approximation in the finite difference time domain (FDTD) method is important in saving computer resources and truncating central processing unit (CPU) time. Previously, thin wires were mainly realized using the true thin wire (TTW) model, in which electric field components along the wire axis are set at zero, and three methods, in which electric field components along the wire axis are also set at zero and the medium around thin wires is replaced depending on wire radius, are hereafter called the RM model. The former is the most conventional and widely used method; however, its resultant radius is 0.23Δs, supposing that the space under consideration is divided by cubic cells with a Δs of the side length of FDTD cells.

The first method of the RM model can realize thin wires having a radius of about 0.15Δs under the conditions we used, in which the time interval is set at a value which is slightly less than Δtc, e.g. 0.9999tc, where Δtc is defined by the Courant condition; in the case of a thin wire having a radius less than 0.15Δs, the FDTD computation suffers from numerical instability. The second method can realize a thin wire having a radius of about 10−4Δs. We need some changes in the numerical electromagnetic analysis program based on the FDTD method to employ these models.

The third of the RM model, which has already been proposed by the author and in which the relative permittivity and relative permeability of four FDTD cells closest to a thin wire are replaced according to the radius of the thin wire and Δs, could realize thin wires having a radius of about 10−6Δs without changing the program and numerical instability.

In this paper, the third model is extensively investigated and it is demonstrated that we can deal with a thin wire with a radius of about 10−9Δs without numerical instability. The maximum difference in the evaluation of the surge impedance of an open‐ended horizontal wire located 5 m above a perfectly conducting ground is less than 5%. We can easily use the third model even though the program, which is available, has no the specific function of thin‐wire approximation. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Role of four‐dimensional ultrasound (spatiotemporal image correlation and Sonography‐based Automated Volume Count) in prenatal assessment of atrial morphology in cardiosplenic syndromes
Authors: Paladini D. , Sglavo G. , Masucci A. , Pastore G. , Nappi C.
Published: March 2011

Objective

To assess the diagnostic role of four‐dimensional ultrasound using spatiotemporal image correlation and Sonography‐based Automated Volume Count (STIC‐SonoAVC) in the identification of the morphology of the atrial appendages in cases with cardiosplenic syndrome.

Methods

This was a retrospective investigation of 22 fetuses with cardiosplenic syndromes seen at our institution over a 5‐year period from January 2004. As control groups, 10 normal fetuses, five cases with a non‐isomeric atrioventricular septal defect and five cases with other congenital heart diseases were also analyzed. For all fetuses, one or more cardiac volume datasets were available for offline analysis. Two‐dimensional and four‐dimensional echocardiography was carried out in all cases at the time of diagnosis using high quality three‐dimensional equipment. Dedicated software was used to assess chamber morphology using the SonoAVC technique, which allows the creation of casts of hollow structures. Two different operators used the software. The first performed all steps up to positioning of the region of interest box. The second operator, who was blinded to clinical information, then rendered the cardiac chambers using the SonoAVC technique. This operator then used the rendered image to subjectively assess atrial morphology.

Results

Suitable rendered images of the cardiac chambers could be produced in 40/42 fetuses. In two cases of left atrial isomerism, advanced (34 weeks) and early (13 weeks) gestational age made it impossible to obtain adequate rendered images. In the remaining 40 cases (13 cases of left atrial isomerism, seven cases of right atrial isomerism, five cases of non‐isomeric atrioventricular septal defect, five cases of other congenital heart diseases and 10 normal fetuses), atrial morphology was correctly identified by evaluation of the rendered images.

Conclusion

Four‐dimensional ultrasound with SonoAVC rendering allows correct identification of the morphology of atrial appendages in all cases of cardiosplenic syndromes in which an adequate cardiac volume dataset can be obtained for analysis. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Retrospective review of diagnostic performance of intracranial translucency in detection of open spina bifida at the 11–13‐week scan
Authors: Fong K. W. , Toi A. , Okun N. , Al‐Shami E. , Menezes R. J.
Published: March 2011

Objectives

To evaluate diagnostic performance of intracranial translucency (IT) for detection of open spina bifida and interobserver agreement for visualization of IT during the 11–13‐week scan.

Methods

A retrospective study was undertaken in a tertiary referral center. Two hundred 11–13‐week scans for nuchal translucency, performed by sonographers certified by The Fetal Medicine Foundation, UK, were reviewed independently for IT by two expert observers. When IT was not seen, the observers determined whether this was due to poor IT image quality or the presence of spina bifida. Discordant cases were reviewed by a third observer and the majority decision was used for analysis. All observers were blinded to individual pregnancy outcome and the number of cases with spina bifida.

Results

There were 191 normal fetuses, eight fetuses with open spina bifida and one with closed spina bifida (this case was excluded from analysis). IT was seen in 150 fetuses and all were normal. In six of the 49 cases in which IT was not seen, IT non‐visibility was attributed to open spina bifida; among these cases, four fetuses had open spina bifida and two were normal. In the remaining 43 cases (including 39 normal fetuses), IT non‐visibility was attributed to inadequate image quality. Sensitivity was 50% (4/8) and specificity was 99% (150/152). Concordance between the two observers concerning IT visibility was 79%, (κ = 0.47, representing moderate agreement).

Conclusion

There was moderate interobserver agreement for visualization of IT on images obtained for nuchal translucency measurement at 11–13 weeks. When IT was confidently seen, open spina bifida could be excluded. However, non‐visibility of IT correctly diagnosed only 50% of fetuses with open spina bifida. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Data mining techniques for information security applications
Authors: Al‐Shawi Amany
Published: March 2011

Information security technology is an essential component for protecting public and private computing infrastructures. With the widespread utilization of information technology applications, organizations are becoming more aware of the security threats to their resources. No matter how strict the security policies and mechanisms are, more organizations are becoming susceptible to a wide range of security breaches against their electronic resources. Network‐intrusion detection is an essential defense mechanism against security threats, which have been increasing in rate lately. It is defined as a special form of cyber threat analysis to identify malicious actions that could affect the integrity, confidentiality, and availability of information resources. Data mining‐based intrusion‐detection mechanisms are extremely useful in discovering security breaches. This article will provide an overview of the applications of data mining techniques in the information security domain. The focus will be on applying data mining to intrusion detection and intrusion prevention. This article will present a critical overview of the research directions in these fields, which will help researchers identify the key practical and research issues essential for building a successful network‐protection system. WIREs Comp Stat 2011 3 221–229 DOI: 10.1002/wics.161

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Data Reduction, Smoothing, and Filtering

Algorithms and Computational Methods > Networks and Security

Statistical Learning and Exploratory Methods of the Data Sciences > Text Mining
Approach to Empyema Necessitatis
Authors: Akgül Asli Gül , Örki Alpay , Örki Tülay , Yüksel Mustafa , Arman Bülent
Published: March 2011

Background

Thoracic empyema is a collection of pus in the pleural space. Empyema necessitatis is a rare complication of empyema, characterized by the dissection of pus through the soft tissues of the chest wall and eventually through the skin. We present nine cases of empyema necessitatis, including etiology, duration, and characteristics of clinical history, kind of surgery used, and treatment choices.

Methods

In a 4‐year period nine patients were treated for empyema necessitatis. Six were male and 3 female with an age range of 13–89 years (median = 40 years).

Results

Empyema necessitatis was treated with drainage and antibiotherapy or antituberculosis therapy in three patients with the diagnosis of tuberculosis or nonspecific pleuritis. Decortication of the thoracic cavity was used in three patients successfully. Others were treated with open drainage. Final diagnoses were tuberculous empyema in five patients, chronic fibrinous pleuritis in three, and squamous cell carcinoma in one. Except for two patients, one with multisystem failure and one with squamous cell carcinoma, all were discharged with no complications.

Conclusion

Surgery plays a critical role in the management of empyema necessitatis in selected patients. Tube drainage, open drainage, and decortication are the choices in variable conditions for obliterating the cavity and regenerating pulmonary function.
Twenty Years of Laparoscopic Fundoplication for GERD
Authors: Dallemagne Bernard , Perretta Silvana
Published: March 2011

The first laparoscopic Nissen fundoplication was performed 20 years ago. Surgical management of gastroesophageal reflux disease (GERD) should be offered only to appropriately studied and selected patients, with the ultimate aim of improving the well‐being of the individual, the “quality of life.” The choice of fundoplication should be dictated by the surgeon’s preference and experience.
The Generalized DINA Model Framework
Authors: de la Torre Jimmy
Published: March 2011

The G-DINA (generalized deterministic inputs, noisy “and” gate) model is a generalization of the DINA model with more relaxed assumptions. In its saturated form, the G-DINA model is equivalent to other general models for cognitive diagnosis based on alternative link functions. When appropriate constraints are applied, several commonly used cognitive diagnosis models (CDMs) can be shown to be special cases of the general models. In addition to model formulation, the G-DINA model as a general CDM framework includes a component for item-by-item model estimation based on design and weight matrices, and a component for item-by-item model comparison based on the Wald test. The paper illustrates the estimation and application of the G-DINA model as a framework using real and simulated data. It concludes by discussing several potential implications of and relevant issues concerning the proposed framework.
Physicochemical Studies on the Interfacial and Micellization Behavior of CTAB in Aqueous Polyethylene Glycol Media
Authors: Manna Kausik , Panda Amiya Kumar
Published: March 2011

Interfacial and micellization behavior of cetyltrimethylammonium bromide (CTAB) have been studied in aqueous polyethylene glycol (PEG) mixed solvent systems of varying concentrations and molar mass. Interfacial behavior of CTAB was investigated by the equilibrium surface tension method. Conductance studies of surfactant solutions under different condition helped in determining the critical micelle concentration (CMC) and degree of dissociation of CTAB micelles. In addition, the limiting molar conductivity of surfactant and micellar species were evaluated from the differential plots. The CMC of CTAB was found to increase with increasing PEG concentration as well as its molar mass, although, the process of interfacial adsorption and micellization was found to be spontaneous, as evidenced by negative free energy change. The viscosity of CTAB micelles in aqueous‐PEG mixtures was found to increase with the increase in PEG concentration and molar mass. Dynamic light scattering measurements revealed a size enhancement effect contributed by the PEG oligomers. An increase in the CMC of CTAB and the subsequent presence of a higher number of ionic species in their dissociated form was further established by an overall increase in the zeta potential value in the presence of PEG oligomers. It is proposed that the PEG could wrap around the micelles through their conformational changes. Results also suggest that PEG oligomers could give solvophobic effect which enhances the CMC of CTAB compared to that in pure water.
Surfactants Based on Bis‐Galactobenzimidazolones: Synthesis, Self‐Assembly and Ion Sensing Properties
Authors: Lakhrissi L. , Hassan N. , Lakhrissi B. , Massoui M. , Essassi E. M. , Ruso J. M. , Solans C. , Rodriguez‐ Abreu C.
Published: March 2011

A series of new non‐ionic amphiphiles based on bis‐galactobenzimidazolones have been synthesized by grafting alkyl bis‐benzimidazolone units as hydrophobic tails on hydroxypropyloxygalacto‐pyranose moieties as hydrophilic heads. Their surface and self‐aggregation properties in water were evaluated. The compounds show very low critical micellar concentrations (CMCs) that decrease with increasing chain length; values for the minimal area per molecule at the interface (Amin) follow the same trend. The synthesized compounds also form hexagonal liquid crystals in water for a certain range of hydrophobic tail lengths. On the other hand, the new amphiphiles show characteristic UV–Vis absorption and fluorescence emission bands associated with the benzimidazolone moiety. The fluorescence emission is quenched with a certain degree of selectivity by cations, due to their strong affinity towards the benzimidazolone group, which shows ion complexation properties. Hence, the reported new amphiphiles are candidates as self‐assembling chemosensors. The quenching efficiency and also ion sensing sensitivity is higher in the monomeric state as compared to the micellar state. The fluorescence emission intensity is higher for compounds with a shorter alkyl chain.
The influence of corporate and political interests on models of illness in the evolution of the DSM
Authors: Pilecki B.C. , Clegg J.W. , McKay D.
Published: March 2011

The diagnostic and statistical manual of mental disorders (DSM) is an evolving document that serves the many mental health care disciplines as the primary reference guide for classifying mental disorders. While the successive framers of the DSM have attempted to base it on scientific evidence, political and economic factors have also shaped the conceptualization of mental illness. These economic and institutional forces have reinforced the DSM's use of a medical model in understanding psychopathology. Though the scientific evidence for a medical model is mixed and evidence for other types of conceptualizations have been given less attention, the medical model provides for reliable diagnoses that allot diverse benefits to treatment providers and researchers, as well as to the pharmaceutical and healthcare industries. This article will outline the development of a medical model of mental illness, highlighting connections between this model and corporate and political interests, and will show how this model relates to the various revisions of, and developments within, the DSM. Such an analysis is especially relevant today as the field looks towards the publication of the newest revision of the DSM and attempts to understand and integrate its proposed changes into current treatment, theory, and research.
Parental bonding in severely suicidal adolescent inpatients
Authors: Freudenstein O. , Zohar A. , Apter A. , Shoval G. , Weizman A. , Zalsman G.
Published: March 2011

Family environment has a clear role in suicidal behavior of adolescents. We assessed the relationship between parental bonding and suicidal behavior in suicidal (n= 53) and non-suicidal (n= 47) adolescent inpatients. Two dimensions of parental bonding: care and overprotection, were assessed with the Parental Bonding Instrument. Results showed that adolescents with severe suicidal behavior tended to perceive their mothers as less caring and more overprotective compared to those with mild or no suicidal behavior. A discriminant analysis distinguished significantly between adolescents with high suicidality and those with low suicidality [χ2(5) = 15.54;p= 0.01] in 71% of the cases. The perception of the quality of maternal bonding may be an important correlate of suicidal behavior in adolescence and may guide therapeutic strategies and prevention.
A Scoping Review of Self‐Management Interventions for Adults With Multiple Sclerosis
Authors: Plow Matthew A. , Finlayson Marcia , Rezac Maggie
Published: March 2011

The purpose of this scoping review is to identify self‐management tasks and skills that are being taught in existing interventions for persons with multiple sclerosis and to describe intervention strategies used to facilitate the learning of self‐management tasks and skills. Multiple strategies were used to search for studies published or in press between 1980 and 2008 that evaluated self‐management interventions. The main exclusion criteria were case studies, inadequate description of the intervention, and traditional clinical patient education interventions. Two independent coders categorized the interventions by using Lorig and Holman's self‐management framework and Abraham and Michie's taxonomy of behavior change techniques. Twenty‐seven interventions were identified from 34 articles. Common intervention topics included fatigue management (n = 12), coping, depression, and stress management (n = 10), and medication management (n = 6). Also, no 2 interventions used the same delivery format to implement the same combination of intervention strategies. Furthermore, markedly different intervention strategies were used to improve the same outcomes. These results highlight a need to systematically test intervention strategies one at a time, or in a clear specified combination, as well as compare existing interventions to determine which are most effective in supporting persons with multiple sclerosis to learn and incorporate self‐management tasks and skills.
Virtual Socialization in Adults With Spina Bifida
Authors: Chan Wendy M. , Dicianno Brad E.
Published: March 2011

Objective

To use spina bifida (SB) as a model of chronic physical disability to study the associations of virtual socialization, friendships, and quality of life (QOL) in adults.

Design

Cross‐sectional survey.

Setting

Subjects were recruited from residential living facilities, outpatient clinics, and the University of Pittsburgh Medical Center (UPMC) research registry.

Patients

Inclusion criteria were age between 18 and 80 years and clinical diagnoses of SB cystica (myelomeningocele) and hydrocephalus. The exclusion criterion was the diagnosis of SB occulta. Sixty‐three eligible adults were enrolled, and all completed the study.

Methods

The survey via questionnaire was performed in person or over the telephone.

Main Outcome Measurements

Data collected included the World Health Organization's Medical Outcomes Study 26‐item Short Form, Economic Self‐Sufficiency from the Craig Handicap Assessment and Reporting Technique Short Form, virtual socializing habits, and number of friends. Three linear regression models were performed, each with a unique dependent variable: number of friends, psychological QOL, or social QOL. The following independent variables were included in all models: age, gender, ethnicity, economic self‐sufficiency, marital status, education level, lesion level, health status, user group, collection method, and time spent virtually socializing. In addition, each regression model included the dependent variables from the other 2 models in its independent variables.

Results

Increased degree of virtual socialization (VS) was associated with a greater number of friends (P = .003, r = .684). Mean (standard deviation) numbers of friends by VS groups were the following: users, n = 4.9 ± 2.7; semi‐users, n = 3.8 ± 2.7; and nonusers, n = 2.1 ± 2.3, which represent a 2.3 times greater number of friends between the users and nonusers. The effect of virtual socialization on QOL was also positive, however, not statistically significant.

Conclusions

People with chronic physical disabilities, such as SB, are at high risk for peer rejection and long‐term social avoidance. Users of the most immersive forms of virtual socialization, have more real world friends than both semi‐users and nonusers. Any form of VS, whether immersive or real time, may improve the opportunity for meaningful social encounters. Prospective intervention studies are needed to elucidate whether a causal positive relationship between virtual socialization and friendships exists. Further research is needed to clarify virtual socialization's impact on QOL; however, the upward trend in all 4 domains of QOL across user groups suggests similar potential benefits.
Effects of 4-week very-high-fructose/glucose diets on insulin sensitivity, visceral fat and intrahepatic lipids: an exploratory trial
Authors: Silbernagel Guenther , Machann Juergen , Unmuth Susanne , Schick Fritz , Stefan Norbert , Häring Hans U. , Fritsche Andreas
Published: March 2011

An increasing amount of fructose in the diet is suggested to play a causal role in the pathogenesis of the metabolic syndrome, type 2 diabetes and fatty liver. Our aim was to investigate and compare the effects of very high fructose and very high glucose in hyperenergetic diets on glucose and lipid metabolism and on fat depots in healthy humans. We conducted an exploratory, prospective, randomised, single-blinded, intervention trial. Participants in addition to a balanced weight-maintaining diet received 150 g of fructose or glucose/d for 4 weeks. Insulin sensitivity was estimated from oral glucose tolerance tests. Visceral and subcutaneous abdominal fat was determined with MRI. Liver fat and intramyocellular lipids of the tibialis anterior muscle were measured with 1H magnetic resonance spectroscopy. A total of twenty healthy subjects (fructose group n 10 and glucose group n 10; twelve males and eight females) completed the study. They had a mean age of 30·5 (sem 2·0) years and a mean BMI of 25·9 (sem 0·5) kg/m2. Insulin sensitivity appeared to decrease both in the fructose and glucose groups. TAG markedly increased in the fructose group. No strong alterations or treatment effects were found for liver fat, visceral fat, subcutaneous abdominal fat and intramyocellular lipids of the tibialis anterior muscle. In conclusion, the effects of very high fructose and very high glucose in hyperenergetic diets on glucose metabolism and body fat composition were not different in the healthy participants of the present study. However, elevation of plasma TAG seemed to be fructose-specific.
Orlistat accentuates the fat-induced fall in blood pressure in older adults
Authors: Tai Kamilia , Gentilcore Diana , Jones Karen L. , Banh Lisa , Gilja Odd Helge , Hammond Angela J. , Feinle-Bisset Christine , Horowitz Michael , Chapman Ian M.
Published: March 2011

Postprandial hypotension may be influenced by the digestion of fat. The aim of the present study was to evaluate the hypothesis that products of fat digestion mediate the hypotensive response to fat. In part A of the study, nine healthy older subjects were studied on three separate occasions in randomised order. Blood pressure, heart rate (HR), plasma TAG and gastric emptying were measured following the ingestion of equivolaemic drinks: (1) 300 ml of high-fat drink (88 % fat); (2) fat drink mixed with 120 mg orlistat (lipase inhibitor); (3) water (control). In part B of the study, ten healthy older subjects were studied on two separate occasions. Blood pressure, HR, plasma TAG and superior mesenteric artery flow were measured during 90 min intraduodenal infusions of 10 % intralipid (2·7 ml/min), with and without 120 mg orlistat. Oral fat ingestion was associated with decreases in systolic and diastolic blood pressures (both P = 0·0001) that were greater when orlistat was co-administered (both P < 0·05), and an increase in HR (P = 0·0001) that was inhibited by orlistat co-administration (P < 0·03). Gastric emptying was slowed by oral fat digestion, and orlistat administration inhibited this slowing (P < 0·04). Intraduodenal fat infusion was not associated with changes in blood pressure but increased HR (P < 0·0001), an effect attenuated by orlistat (P < 0·05). In conclusion, orlistat potentiates the hypotensive response to oral fat in older adults, possibly as a result of faster gastric emptying of fat. The results do not support a role for fat digestion in lowering blood pressure.
Variations on a beta-plane: derivation of non-traditional beta-plane equations from Hamilton's principle on a sphere
Authors: DELLAR PAUL J.
Published: March 2011

Starting from Hamilton's principle on a rotating sphere, we derive a series of successively more accurate β-plane approximations. These are Cartesian approximations to motion in spherical geometry that capture the change with latitude of the angle between the rotation vector and the local vertical. Being derived using Hamilton's principle, the different β-plane approximations each conserve energy, angular momentum and potential vorticity. They differ in their treatments of the locally horizontal component of the rotation vector, the component that is usually neglected under the traditional approximation. In particular, we derive an extended set of β-plane equations in which the locally vertical and locally horizontal components of the rotation vector both vary linearly with latitude. This was previously thought to violate conservation of angular momentum and potential vorticity. We show that the difficulty in maintaining these conservation laws arises from the need to express the rotation vector as the curl of a vector potential while approximating the true spherical metric by a flat Cartesian metric. Finally, we derive depth-averaged equations on our extended β-plane with topography, and show that they coincide with the extended non-traditional shallow-water equations previously derived in Cartesian geometry.
Inviscid critical and near-critical reflection of internal waves in the time domain
Authors: SCOTTI ALBERTO
Published: March 2011

A solution that describes the inviscid reflection of internal waves off a sloping bottom in time is derived under conditions of linearity and uniform stratification. The solution is well behaved even under critical conditions. In the region ky < Nt, where k is the along-slope wavenumber of the incoming wave, y is the slope-normal direction, N is the Brünt–Väisälä frequency and t is time, an approximation can be written in terms of Lommel's function of two variables. The analysis can easily be extended to the case of a beam of finite width. In the non-critical case, the streamfunction relaxes to the classical Phillips steady-state solution in the region y < cgt, where cg is the slope-normal component of the group velocity for waves at the forcing frequency. However, it is found that the region where the along-boundary component of the velocity relaxes to the Phillips solution is also bounded from below, leaving a region very close to the wall where the classical solution misses important elements of the reflectionprocess. This leads to interesting properties near the boundary, especially relatively to the formation of shear-driven unstable conditions.
Leakage from inclined porous reservoirs
Authors: ZIMOCH PAWEL J. , NEUFELD JEROME A. , VELLA DOMINIC
Published: March 2011

We investigate the effect of localized leakage on the storage of buoyant fluids in inclined porous reservoirs, with application to the geological storage of CO2. We find that once the current has propagated some distance beyond the point of leakage, its profile becomes steady in time, save for the nose, which advances at a constant speed. Crucially, this steady state implies that the efficiency of storage (defined as the instantaneous proportion of the injected fluid that does not leak) tends to a finite value. This contrasts with previous studies of localized leakage in horizontal reservoirs, which found that the efficiency of storage tends to zero at late times. We analyse the steady-state efficiency and the time scales of evolution for a leakage point located either upslope or downslope of the injection point using analytical and numerical methods. These findings are verified by model laboratory experiments. Finally, we consider the implications of our results for the geological storage of CO2 under sloping cap rocks compromised by a fracture or fissure.