bluuebunny/crossref_metadata_2025 huggingface dataset:
SUMOylation of the Human Cytomegalovirus 72-Kilodalton IE1 Protein Facilitates Expression of the 86-Kilodalton IE2 Protein and Promotes Viral Replication
Authors: Nevels Michael , Brune Wolfram , Shenk Thomas
Published: June 2004

The 72-kDa immediate-early 1 protein (IE1-72kDa) of human cytomegalovirus has been previously shown to be posttranslationally modified by covalent conjugation to the ubiquitin-related protein SUMO-1. Using an infectious bacterial artificial chromosome clone of human cytomegalovirus, we constructed a mutant virus (BADpmIE1-K450R) that is deficient for SUMOylation of IE1-72kDa due to a single amino acid exchange in the SUMO-1 attachment site. Compared to wild-type virus, this mutant grew more slowly and generated a reduced yield in infected human fibroblasts, indicating that SUMO modification is required for the full activity of IE1-72kDa. The lack of SUMOylation did not affect the intranuclear localization of IE1-72kDa, including its ability to target to and disrupt PML bodies and to bind to mitotic chromatin. Likewise, SUMOylation-deficient IE1-72kDa activated several viral promoters as efficiently as the wild-type protein. However, the failure to modify IE1-72kDa resulted in substantially reduced levels of the IE2 transcript and its 86-kDa protein (IE2-86kDa). These observations suggest that SUMO modification of IE1-72kDa contributes to efficient HCMV replication by promoting the accumulation of IE2-86kDa.
Biased Hypermutagenesis Associated with Mutations in an Untranslated Hairpin of an RNA Virus
Authors: McCormack John C. , Simon Anne E.
Published: June 2004

The mutation frequency of
Turnip crinkle virus
can increase 12-fold without inducing error catastrophe. Lesions in a hairpin repressor frequently reverted and led to second-site alterations biased for specific mutations. These results suggest that the hairpin may also function as an RNA chaperone to properly fold the RNA-dependent RNA polymerase.
Bromodeoxyuridine-Labeled Viral Particles as a Tool for Visualization of the Immediate-Early Events of Human Cytomegalovirus Infection
Authors: Rosenke Kyle , Fortunato Elizabeth A.
Published: June 2004

We describe here a simple method for labeling the genome of human cytomegalovirus, a large double-stranded DNA virus, with bromodeoxyuridine (BrdU). The labeled DNA was incorporated into viral particles, which were then collected in cell supernatant. To demonstrate the versatility and effectiveness of this method, labeled virions were used to study the immediate-early events of virus-host cell interaction via indirect immunofluorescence microscopy. It is our hope that this new methodology will prove useful in the study of binding, entry and viral genome deposition in diverse virus systems.
Human Coronavirus 229E Nonstructural Protein 13: Characterization of Duplex-Unwinding, Nucleoside Triphosphatase, and RNA 5′-Triphosphatase Activities
Authors: Ivanov Konstantin A. , Ziebuhr John
Published: June 2004

The human coronavirus 229E (HCoV-229E) replicase gene-encoded nonstructural protein 13 (nsp13) contains an N-terminal zinc-binding domain and a C-terminal superfamily 1 helicase domain. A histidine-tagged form of nsp13, which was expressed in insect cells and purified, is reported to unwind efficiently both partial-duplex RNA and DNA of up to several hundred base pairs. Characterization of the nsp13-associated nucleoside triphosphatase (NTPase) activities revealed that all natural ribonucleotides and nucleotides are substrates of nsp13, with ATP, dATP, and GTP being hydrolyzed most efficiently. Using the NTPase active site, HCoV-229E nsp13 also mediates RNA 5′-triphosphatase activity, which may be involved in the capping of viral RNAs.
A Human Cellular Protein Activity (OF-1), Which Binds Herpes Simplex Virus Type 1 Origin, Contains the Ku70/Ku80 Heterodimer
Authors: Murata Lauren B. , Dodson Mark S. , Hall Jennifer D.
Published: June 2004

In an effort to identify host proteins involved in herpes simplex virus type 1 replication, monkey and human cellular protein activities (called OF-1) that bind the viral replication origin, oriS, have been described. We show by mass spectrometry that the DNA-binding component of human OF-1 contains Ku70 and Ku80 proteins.
Lentiviral Transduction of Dendritic Cells Confers Protective Antiviral Immunity In Vivo
Authors: Zarei Shohreh , Abraham Shahnaz , Arrighi Jean-Francois , Haller Olivier , Calzascia Thomas , Walker Paul R. , Kündig Thomas M. , Hauser Conrad , Piguet Vincent
Published: June 2004

Control of a viral infection in vivo requires a rapid and efficient cytotoxic-T-lymphocyte response. We demonstrate that lentivirus-mediated introduction of antigen in dendritic cells confers a protective antiviral immunity in vivo in a lymphocytic choriomeningitis virus model. Therefore, lentiviral vectors may be excellent vaccine candidates for viral infections.
The 3′
cis
-Acting Genomic Replication Element of the Severe Acute Respiratory Syndrome Coronavirus Can Function in the Murine Coronavirus Genome
Authors: Goebel Scott J. , Taylor Jill , Masters Paul S.
Published: June 2004

The 3′ untranslated region (3′ UTR) of the genome of the severe acute respiratory syndrome coronavirus can functionally replace its counterpart in the prototype group 2 coronavirus mouse hepatitis virus (MHV). By contrast, the 3′ UTRs of representative group 1 or group 3 coronaviruses cannot operate as substitutes for the MHV 3′ UTR.
An optimised protocol for the extraction of non-viral mRNA from human plasma frozen for three years
Authors: Wong S C C , Lo E S F , Cheung M T
Published: June 2004

Aims:To detect non-viral mRNA in human plasma that has been frozen for three years using a new protocol.

Methods:Plasma from 15 patients with colorectal cancer and 10 normal subjects was separated and frozen with Trizol at −80°C for three years. As a control measure, plasma from 10 of the 15 patients was separated using the same protocol but no Trizol during storage. After three years, all samples were extracted using Trizol and RNeasy before the reverse transcriptase polymerase chain reaction was performed to detect non-viral β catenin mRNA. In addition, extraction of three plasma samples by Trizol or RNeasy independently was carried out for comparison.

Results:β Catenin mRNA was detected in all 15 patient plasma samples and only one of the 10 normal subjects. In contrast, no β catenin mRNA was found in the control and patient samples that were independently extracted by Trizol and RNeasy kit.

Conclusions:This new protocol is a reliable method for extracting non-viral mRNA from the plasma of patients with cancer after longterm storage for three years. Extractions using Trizol and RNeasy kits independently could not isolate mRNA with sufficient quantity and quality for detection.
Quality control in diagnostic molecular pathology in the Netherlands; proficiency testing for patient identification in tissue samples
Authors: Thunnissen F B J M , Tilanus M G J , Ligtenberg M J L , Nederlof P M , Dinjens W N M , Meulemans E , Van den Brule A J C , van Noesel C J M , de Leeuw W J F , Schuuring E
Published: June 2004

Aims:To describe the evolution of proficiency testing for molecular diagnostic pathology with respect to determining unambiguously the patient identity of tissue samples by microsatellite analysis.

Method:Four rounds of quality control exchanges of samples from different patients were sent with the purpose of identifying the correct origin of these samples. The samples were either paraffin wax embedded sections on glass, sections in tubes, or isolated DNA. Blinded samples were distributed to all participating laboratories. No restrictions to the method and short tandem repeat markers used for identification were imposed.

Results:In four subsequent rounds the number of participating laboratories increased from three to 10. The numbers of samples tested increased in time from five to 12. The microsatellite markers used by the different laboratories showed little overlap. In the first three rounds, in which isolated DNA was provided, all samples were accurately classified irrespective of the microsatellite markers used. In the last round, which also included paraffin wax embedded sections, a small number of laboratories experienced problems, either with amplification or incorrect classification of a few samples.

Conclusion:Proficiency testing was useful, and showed country wide high quality and correct identification of (patient) samples with molecular techniques for diagnostic purposes.
Plasma glucose measurement with the Yellow Springs Glucose 2300 STAT and the Olympus AU640
Authors: Twomey P J
Published: June 2004

Background:Diabetes mellitus is an important diagnosis. New criteria have been defined for impaired glucose metabolism and, accordingly, there is a need for precise and accurate glucose analysis for the correct classification of patients. However, neither the World Health Organisation nor the National Service Framework for Diabetes in England and Wales deal with the associated analytical issues for plasma glucose.

Aims/Methods:To compare two different methods for plasma glucose with respect to European and CLIA ’88 quality requirements.

Results:Using several different graphical and statistical techniques, the YSI 2300 STAT was found to be 8.1–8.4% negatively biased for plasma glucose when compared with the Olympus AU640 method.

Conclusions:Such a large bias would have a large impact on the detection of diabetes mellitus in clinical practice and therefore this method should not be used to make a definitive diagnosis. The bias probably results from the fact that the YSI 2300 STAT uses an aqueous based standard.
Lack of lymphangiogenesis during breast carcinogenesis
Authors: Vleugel M M , Bos R , van der Groep P , Greijer A E , Shvarts A , Stel H V , van der Wall E , van Diest P J
Published: June 2004

Background:Recent evidence suggests that functional intratumorous lymph vessels may be absent from some human cancers. This could result from either the failure of tumours to induce lymphangiogenesis, or the collapse of lymph vessels, caused by high interstitial tumour pressure.

Methods:To differentiate between these two hypotheses, paraffin wax embedded clinical specimens from normal breast (n  =  13), usual ductal hyperplasia (n  =  11), ductal carcinoma in situ (n  =  21), and invasive breast cancer (n  =  40) were compared for lymphatic and blood vessel density by immunohistochemistry with antibodies to the lymphatic endothelial hyaluronan receptor (LYVE-1) and CD31, respectively.

Results:Lymph vessel density was lower than blood vessel density in normal breast tissue. Within breast lobuli, lymph vessels were absent. In premalignant lesions blood microvessel density increased, whereas no increase in lymph vessels could be seen intralesionally. In invasive cancers, lymph vessels were absent in all but a few cases, where probably some pre-existing lymph vessels remained, although blood microvessel density was once again increased.

Conclusion:Unlike angiogenesis, lymphangiogenesis is absent during breast carcinogenesis. This, and not rising interstitial pressure caused by an increase in the size of lesions, explains the absence of intratumorous lymph vessels in invasive breast cancer.
Versican expression in pharyngeal squamous cell carcinoma: an immunohistochemical study
Authors: Pukkila M J , Kosunen A S T , Virtaniemi J A , Kumpulainen E J , Johansson R T , Kellokoski J K , Nuutinen J , Kosma V-M
Published: June 2004

Aims:To study the expression of versican, a large proteoglycan involved in repressing adhesion between cells and the extracellular matrix in pharyngeal squamous cell carcinoma (PSCC), and its relation to the expression of p53 and catenins, histological differentiation, clinical data, and prognosis.

Methods:For the retrospective survey, primary tumours for analyses were obtained from 118 patients diagnosed with PSCC of the oropharynx or hypopharynx. The immunohistochemical expression of versican was studied and was related to the expression pattern of p53 and catenins, in addition to clinical data and survival.

Results:In the primary tumours, strong stromal versican expression was graded as low in 59 (50%) and high in 59 (50%) cases. In addition, intracellular versican staining was seen in nine (8%) tumours. In local lymph node metastases, strong stromal versican staining was significantly more frequent compared with the primary tumours (p  =  0.018). Strong stromal versican staining was more frequently seen in less advanced tumours (p  =  0.015). There was no association between versican expression and the other investigated variables (p53, catenins, TNM status, and histological grade). Neither stromal nor intracellular versican expression predicted overall survival in these patients.

Conclusions:Versican was more strongly expressed in the stroma of local metastases and in the earlier stages of disease in PSCC. However, versican expression was not an independent prognostic factor in this entity.
Technical variations in prostatic immunohistochemistry: need for standardisation and stringent quality assurance in PSA and PSAP immunostaining
Authors: Varma M , Berney D M , Jasani B , Rhodes A
Published: June 2004

Aims:To assess variations in prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) immunohistochemistry with particular reference to the antibody type (monoclonal or polyclonal) and the tissues used for optimising immunostaining conditions and as external positive controls.

Methods:A questionnaire was sent to all laboratories registered with the UK National External Quality Assurance Scheme for immunohistochemistry enquiring about the immunohistochemical methods routinely used for the diagnosis of prostate cancer.

Results:Responses were received from 220 (68%) laboratories. All UK respondents routinely performed PSA immunostaining but PSAP immunostaining was available in only 57% of these laboratories. Monoclonal anti-PSA, polyclonal anti-PSA, monoclonal anti-PSAP, and polyclonal anti-PSAP were used by 40%, 60%, 29%, and 27% of UK respondents, respectively. Benign prostate tissue was most commonly used to determine optimal antibody dilutions and as external quality control for PSA/PSAP, with only 6% and 3% of respondents, respectively, including high grade prostate cancer in the tissues used for these purposes.

Conclusions:The wide variation in the methods used highlights the need for standardisation and more stringent quality assurance of the immunohistochemical staining techniques used for PSA and PSAP. The widespread use of benign prostate tissue to determine optimal antibody dilutions and as an external positive control for PSA and PSAP immunostaining is of particular concern because this approach may result in a method that is not sufficiently sensitive to detect the reduced PSA and PSAP expression associated with high grade prostate cancer.
My approach to serrated polyps of the colorectum
Authors: Higuchi T , Jass J R
Published: June 2004

Hyperplastic polyps of the colorectum are heterogeneous lesions, a subset of which is now regarded as the precursor of colorectal cancer with DNA microsatellite instability. Some authors have distinguished this subset from classic hyperplastic polyps and have introduced the term “sessile serrated adenoma”. These lesions frequently show BRAF mutation and DNA methylation. This personal perspective reviews recent insights into serrated polyps and highlights the importance of inhibition of apoptosis as a unifying mechanism. It is estimated that around 25 hyperplastic polyps of the proximal colon exist for every colorectal cancer with DNA microsatellite instability. Further research is required to identify additional risk factors for hyperplastic polyps other than anatomical location. These may be demographic, clinical, morphological, or molecular. It is not recommended that the term sessile serrated adenoma be used in routine reporting, but it is desirable that potentially aggressive hyperplastic polyps should be identified for the purposes of both clinical practice and research.
Are heterogenous results of EGFR immunoreactivity in renal cell carcinoma related to non-standardised criteria for staining evaluation?
Authors: Langner C , Ratschek M , Rehak P , Schips L , Zigeuner R
Published: June 2004

Aims:To assess whether heterogeneity of epidermal growth factor receptor (EGFR) immunoreactivity in renal cell carcinoma (RCC) is related to non-standardised criteria for staining evaluation.

Methods:EGFR expression was investigated in 132 primary and 55 metastatic conventional RCCs using a tissue microarray technique.

Results:Overall, membranous and/or cytoplasmic EGFR immunostaining was present in 123 of 132 (93%) primary and 49 of 53 (92%) metastatic RCCs, with extensive immunoreactivity (> 50% of tumour cells) in 110 of 132 (83%) primary tumours and 39 of 53 (73%) metastases. Cytoplasmic staining was associated with high tumour stage and high tumour grade. In addition, strong membranous staining (score 3+) prevailed in high grade RCCs. Cytoplasmic immunostaining was associated with an unfavourable prognosis, whereas overall (cytoplasmic and membranous) immunoreactivity and intensity of membranous staining were not.

Conclusions:Different methods of immunohistochemical evaluation led to different results, strengthening the need for standardisation, especially against a background of rapidly evolving EGFR targeted cancer treatment strategies.
The value of an elastic tissue stain in detecting venous invasion in colorectal cancer
Authors: Vass D G , Ainsworth R , Anderson J H , Murray D , Foulis A K
Published: June 2004

Background:Venous invasion by tumour is an independent prognostic indicator of both prognosis and risk of development of distant metastases in colorectal carcinoma. The use of special stains to aid its detection in pathology specimens is not currently universally recommended.

Aims:To determine whether an elastica stain significantly increases the incidence of detection of vascular invasion compared with routinely stained sections.

Methods:Serial sections from the 75 cases of colorectal carcinoma were stained by haematoxylin and eosin (H&E) only and elastica counterstained with H&E. The incidence of both intramural and extramural venous invasion was recorded and compared with that seen when the tumours were originally reported.

Results:Extramural venous invasion had been noted in 14 of the pathology reports and was seen in 18 cases when only the H&E sections were viewed in the study. It was present in 32 cases when elastica stained sections were analysed. Intramural venous invasion was seen in eight cases on H&E sections and 30 cases on elastica stained sections.

Conclusion:The use of elastica stained serial sections to detect venous invasion in tumours should be recommended in guidelines for the reporting of colorectal carcinomas.
Cardiac metastasis from a bronchial carcinoid: report of a case presenting with diffuse thickening of the left ventricular wall
Authors: Goddard M J , Atkinson C
Published: June 2004

Bronchial carcinoids are low grade malignancies with an excellent prognosis and a low incidence of metastases. This report describes a case of a typical carcinoid tumour with metastases to the spine after four years and to the heart after eight years. Carcinoid tumours rarely metastasise to the heart and previous reports have identified gastrointestinal primaries as the source in most cases. This is the first published case of typical carcinoid tumour that metastasised to the heart from a bronchial primary.
High molecular weight caldesmon positive stromal cells in the capsule of hepatocellular carcinomas: Figure 1
Authors: Nakayama H , Enzan H , Yamamoto M , Miyazaki E , Yasui W
Published: June 2004

Aims:To investigate the smooth muscle nature of the stromal cells in the capsule of hepatocellular carcinomas.

Methods:Immunohistochemical analysis using monoclonal antibody to high molecular weight caldesmon (HCD), a highly specific marker for smooth muscle cells, was performed in 33 encapsulated hepatocellular carcinomas and adjacent hepatic tissues.

Results:HCD positive stromal cells were detected in the capsule of 21 of the 33 hepatocellular carcinomas examined.

Conclusions:The capsule of hepatocellular carcinomas contains smooth muscle cells.
FAIR SCHEDULING WITH DYNAMIC RESOURCE ALLOCATION IN CDMA/GPS SYSTEM FOR IP-MULTIMEDIA WIRELESS NETWORKS
Authors: MENDEZ ALDO , COVARRUBIAS DAVID , BRIZUELA CARLOS
Published: June 2004

Over the last few years, research has provided the cellular network system with the capability of fair channel access to multimedia users, while at the same time, insuring a given QoS and optimal utilization of network resources. Scheduling policies play a crucial role in achieving desired QoS goals and optimum utilization of limited resources. Many scheduling approaches have been proposed for the efficient utilization of the network resources. This paper deals with the experimental study of a new proposed scheduling policy for achieving fairness, QoS, and optimal use of resources. The proposed scheduling policy Code Division Multiple Access based on Generalized Processor Sharing with Dynamic Weights (CDMA/GPS-DW) is an improvement of a previous GPS policy. Simulation results show that the proposed policy achieves fairness of the specified QoS and makes efficient use of the network resources.
COHERENT SS DEMODULATION WITH ESTIMATION AND COMPENSATION OF PHASE ROTATION USING A PILOT CHANNEL
Authors: IIJIMA YASUYUKI , INOUE SHIGEYUKI , KASHIMA TOMOKO , FUKASAWA ATSUSHI , TAKIZAWA YUMI
Published: June 2004

This paper describes and clarifies a configuration and its performance of estimation and compensation of phase rotation in radio propagation using a pilot channel for the SS (spread spectrum) modulation and demodulation.

Coherent radio transmission scheme is composed as follows: (i) Continuous pilot signal is transmitted through a pilot channel, (ii) the pilot channel is composed of O-QPSK and QPSK for reverse and forward links, respectively, (iii) pilot signal is added in each I channel of O-QPSK and QPSK, and (iv) coherent demodulation is achieved by estimation and compensation of phase rotation using the pilot channel.

Phase rotation and its linearity has been estimated for QPSK and O-QPSK data modulation methods. The constellation on the complex plane is used for the evaluation of phase rotation and the Eye pattern for the demodulated waveforms. The bit-error-rate (BER) versus Eb/N0 is used for the characteristics of data modulation/demodulation and SS modulation/demodulation of the proposed radio system.

A proposed scheme proved that (i) estimation of rapid phase rotation caused by multipath radio propagation with high-speed Doppler shift in frequency is well realized by the use of continuous pilot transmission (pilot channel), (ii) compensation of rapid phase rotation is well done by simplified logic operations, and (iii) high performance for high speed data transmission is realized by coherent demodulation. This system will be applied to wireless LANs with high performances and simplified configurations.
CONTEXT MANAGEMENT IN VIRTUAL HOME ENVIRONMENT SYSTEMS
Authors: XYNOGALAS STAVROS , ROUSSAKI IOANNA , CHANTZARA MARIA , ANAGNOSTOU MILTIADES
Published: June 2004

The emerging 3rd generation services are provided through various types of networks and terminals. Roaming users rely on new kinds of wireless networks and terminals to offer mobility and make services available everywhere. The users' requirement for continuous access to personalized services from any place, transparently and independently of the underlying network technology and the terminal or point of access, was satisfied by the first VHE prototypes. The challenge in service engineering is now to make these services smarter by adding context management capabilities to them. In this paper we propose an enhanced framework for efficient context management in a VHE environment.
NEWTONIAN MECHANICS AND NASH PLAY
Authors: FLÅM S. D. , MORGAN J.
Published: June 2004

Nash equilibrium leaves the impression that each player foresees perfectly and responds optimally. Must human-like, rational agents really acquire both these faculties? This paper argues that in some instances neither is ever needed. For the argument repeated play is modelled here as a constrained, decentralized, second-order process driven by noncoordinated pursuit of better payoffs. Some friction feeds into — and stabilizes — a fairly myopic mode of behavior. Convergence to equilibrium therefore obtains under weak and natural conditions. An important condition is that accumulation of marginal payoffs, along the path of play, yields a sum which is bounded above.
GEOMETRY AND COMPUTATION OF THE LORENZ SET
Authors: ARIN JAVIER , KUIPERS JEROEN , VERMEULEN DRIES
Published: June 2004

In this paper we study the geometrical properties of the set of Lorenz allocations of a transferable utility game. We provide procedures to compute a single Lorenz allocation, and even the entire set of Lorenz allocations, that rely solely on linear optimization techniques. These procedures only require a finite number of elementary operations and are therefore easy to implement.
THE FORGIVING TRIGGER STRATEGY: AN ALTERNATIVE TO THE TRIGGER STRATEGY
Authors: ARAMENDIA M. , RUIZ L. , VALENCIANO F.
Published: June 2004

The grim-trigger strategy introduced by Friedman is often used in economic models, mainly because of its simplicity, to show that collusion can be sustained by means of a subgame perfect equilibrium. In this work we show that, under simple conditions, it is possible to improve on the grim-trigger strategy while retaining subgame perfection and in some cases adding weak renegotiation proofness (in the sense of Farrell and Maskin). The basic idea is that, following a deviation, the cheater, instead of continuing in the Nash equilibrium forever, chooses an autopenalty which signals, in a very strong way, that he/she would not deviate any more if cooperation were reestablished. We check the nice working of this strategy in the Cournot's oligopoly model.
BARGAINING MODEL WITH SEQUENCES OF DISCOUNT RATES AND BARGAINING COSTS
Authors: RUSINOWSKA AGNIESZKA
Published: June 2004

The paper is a kind of generalization of Rubinstein bargaining model. Rubinstein assumed that preferences of the players were constant in time, and he analyzed models in which preferences of each player were defined either by constant discount rate or by constant bargaining cost. In this paper, a bargaining model is presented, in which preferences of each player are expressed simultaneously by sequence of discount rates and sequence of bargaining costs varying in time. The results presented in the paper concern subgame perfect equilibria. There is a theorem concerning sufficient and necessary conditions for the existence of subgame perfect equilibrium of the game. Moreover, some theorems presenting forms of subgame perfect equilibria for various cases of the model analyzed have been proved here. A possibility of delay in reaching an agreement is also considered in the paper. If we analyze a class of strategies, that depend on the former history, a delay can appear for some models. The adequate examples are presented. In the paper, some applications of the bargaining model are also described.
DEVIATION FROM EXACT CONDUCTANCE QUANTIZATION IN A SHORT CLEAN ONE-DIMENSIONAL CHANNEL
Authors: LIANG C.-T. , TKACHENKO O. A. , TKACHENKO V. A. , BAKSHEYEV D. G. , SIMMONS M. Y. , RITCHIE D. A. , PEPPER M.
Published: June 2004

We have experimentally found that the height of quantized conductance steps of a short constriction in a two-dimensional electron gas can reduce by 3% as compared to 2e2/h. We explain this phenomenon by different shift of one-dimensional subbands in response to changing gate voltage. Both simple analytical estimate and realistic modeling of the device yield the same magnitude of the effect as that in experiment.
HOT PHOTOLUMINESCENCE STUDY OF MINIBAND EFFECTS IN GaAs/AlAsSLs
Authors: MIRLIN D. N. , SAPEGA V. F. , USTINOV V. M.
Published: June 2004

We report the study of the effect of miniband width on polarization properties of the hot electron photoluminescence (HPL) in SLs . It is demonstrated that the energy and magnetic field dependencies of the HPL polarization are very sensitive to the electron miniband widths. We show that high magnetic field applied perpendicular to the SL growth direction (Voigt geometry) induces transition (magnetic field breakdown) between electron minibands. The vertical transport of spin polarized and momentum aligned hot electrons is studied.
POLARIZATION DEPENDENCE OF PHOTOSENSITIVITY OF THE SCHOTTKY BARRIER DIODES BASED ON THE InGaAs/GaAs QUANTUM WELL STRUCTURES
Authors: FILATOV D. O. , KARPOVICH I. A. , SHILOVA T. V. , Ya. DEMIKHOVSKII V. , KHOMITSKIY D. V.
Published: June 2004

The polarization dependence of the photosensitivity (PS) of the Schottky barrier photodiodes based on the InGaAs / GaAs quantum well (QW) structures has been studied using the in-plane photoexcitation of the QW by linearly-polarized light through a cleaved facet. The interband optical transitions involving the quantum confined heavy-hole (hh) and the light hole (lh) states were identified in the PS spectra by their different polarization dependences. The latter follow the theoretical ones for the absorption coefficient with good agreement. The effect of lifting of the polarization selection rules in the QW due to the hh and lh mixing at the QW heterointerface has been studied both theoretically and experimentally. The importance of taking this effect into account in analysis of the PS polarization dependence in the excited state transition bands has been shown.
SPECTRUM OF CARRIERS AND OPTICAL PROPERTIES OF 2D HETEROSTRUCTURES IN TILTED MAGNETIC FIELD
Authors: GRESHNOV A. A. , KOLESNIKOVA E. N. , ZEGRYA G. G.
Published: June 2004

The structure and features of spatially-confined states in the presence of a tilted magnetic field are theoretically investigated. The electron states in single- and double-quantum wells are described using the variational method. It is shown that the finite ratio of magnetic length to the width of heterostructure could not be neglected in the strong tilted magnetic field. The electronic structure of broken-gap heterostructures is considered similar to the case of usual double-quantum-well with the high narrow barrier. It is shown that tilted magnetic field can eliminate the strong coupling between two degenerated electron states or those of the electron and hole. The existence of such an effect is in accordance with cyclotron resonance studies of InAs / GaSb heterostructures.
HOLE STATES LOCALIZED AT TYPE II HETEROINTERFACE
Authors: NESTOKLON M. O.
Published: June 2004

A theory of Tamm-like hole states at type II heterointerface has been developed for zink-blende semiconductors. The consideration has been carried out in the microscopic tight-binding model with allowance made for the spin-orbit splitting of the valence band. It has been demonstrated that the tight-binding method describes Tamm-like hole states at type II semiconductor interface. Localization energy dependence on interface tight-binding parameters has been analyzed.
BYCHKOV–RASHBA SPLITTING IN INVERSION LAYERS ON HEAVILY-DOPED p-HgCdTe
Authors: RADANTSEV V. F. , KULAEV G. I. , KRUZHAEV V. V.
Published: June 2004

The Bychkov–Rashba effect in metal–insulator–semiconductor (MIS) structures based on zero-gap HgCdTe with different doping level is investigated experimentally and theoretically. The relative difference between electron concentration in different spin-orbit split sub-subband increases with doping and reaches high values as Δn/n~0,5 at NA-ND~1018 cm-3. Contrary to low-doped HgCdTe the splitting, in the samples investigated, exhibits strong concentration dependence in the wide concentration region.
EXCITED STATE PHOTOLUMINESCENCE IN STEPPED InGaAs/AlGaAs QUANTUM WELLS UNDER PICOSECOND EXCITATION
Authors: SHALYGIN V. A. , VOROBJEV L. E. , Yu. PANEVIN V. , FIRSOV D. A. , HANNA S. , KNIELING H. , SEILMEIER A. , ARAKTCHEEVA E. M. , KRYZHANOVSKAYA N. V. , GLADYSHEV A. G. , ZHUKOV A. E. , USTINOV V. M.
Published: June 2004

The technique of photoluminescence (PL) studies based on intense picosecond excitation of electron–hole pairs is applied to investigate the electron energy structure including the positions of high-lying excited levels in stepped quantum wells (QWs). The spectra of PL in regimes of spontaneous and stimulated emission are studied under different excitation levels and light polarizations. Of special interest are intense photoluminescence signals from excited subbands. The feasibility of a e3–e2 intersubband population inversion in stepped QWs is demonstrated and the influence of Auger recombination was examined.
INTERSUBBAND SPECTROSCOPY IN QUANTUM WELL STRUCTURES AT HIGH NONEQUILIBRIUM CARRIER DENSITIES
Authors: SEILMEIER A. , HANNA S. , SHALYGIN V. A. , FIRSOV D. A. , VOROBJEV L. E. , USTINOV V. M. , ZHUKOV A. E.
Published: June 2004

In the present paper, the electronic intersubband transitions in semiconductor quantum well structures are investigated using transient mid infrared absorption spectroscopy after interband photoexcitation with intense picosecond pulses in the visible spectral range. The focus of our investigations is on the e2–e3 intersubband transition in an asymmetric undoped GaAs / AlGaAs quantum well (QW) structure at room temperature. At injected nonequilibrium carrier densities of 1×1013 cm -2 per QW, an e2–e3 absorption band at 99 meV is found which is blue-shifted with increasing carrier density. Intersubband absorption signals are distinguished from free-carrier absorption signals in the mid infrared (MIR) by their characteristic time behavior.
TEMPORAL DYNAMICS OF EXCITON–TRION SYSTEM
Authors: KOCHERESHKO V. P. , PLATONOV A. V. , MIKHAILOV G. V. , PULS J. , HENNEBERGER F. , YAKOVLEV D. R. , FASCHINGER W.
Published: June 2004

Time-resolved and time-integrated circularly-polarized photoluminescence of excitons and trions have been studied in external magnetic fields up to 10 T. ZnSe-based quantum well structures of n-type with carrier densities varied from 5×109 to 1011 cm -2 were used in this study. Absence of the chemical equilibrium in the exciton–trion system has been demonstrated at low temperatures (<10 K ). The recovery of the equilibrium has been found at elevated temperatures (<15 K ).
FEW-PARTICLE ANYON EXCITON: EXACT SOLUTIONS
Authors: PARFITT D. G. W. , PORTNOI M. E.
Published: June 2004

The anyon exciton model, which describes an exciton against the background of an incompressible quantum liquid, is generalized to the case of an arbitrary number of anyons. Some mathematical aspects of this quantum-mechanical few-particle problem are considered and several exact solutions are obtained. The four-particle case is also considered in the classical limit in both planar and spherical geometries. Such a classical approach gives an adequate description of an anyon exciton at large separation between the valence hole and the two-dimensional electron gas. It is shown that in this limit in a planar geometry the anyon exciton is always energetically more favorable than a charged anyon ion. This indicates that the appearance of fractionally-charged anyon ions reported in recent numerical calculations is an artefact apparently caused by finite-size effects in a spherical geometry.
OPTICALLY-DETECTED MICROWAVE RESONANCE IN InGaAsN/GaAs QUANTUM WELLS AND InAs/GaAs QUANTUM DOTS EMITTING AROUND 1.3 μm
Authors: BARANOV P. G. , ROMANOV N. G. , PREOBRAZHENSKI V. L. , Yu. EGOROV A. , USTINOV V. M. , SOBOLEV M. M.
Published: June 2004

Optically-detected magnetic resonance (ODMR) and optically-detected cyclotron resonance (ODCR) were applied to study two types of nanostructures emitting around 1.3 μm: quantum wells with low nitrogen content and InAs / GaAs quantum dots (both isolated and vertically-coupled). ODMR with the axial symmetry (effective g factor |g‖|=3.61 and |g⊥|=0.7) was found in unannealed InGaAsN / GaAs multiple-quantum well structures and ascribed to electrons in the quantum wells; the sign of g factor is suggested to be negative. There is evidence that before annealing the InGaAsN / GaAs structure has properties, which are typical for quantum wells, but after annealing the structure is completely-changed and resembles a quantum-dot-like structure. The effect of cyclotron resonance on the luminescence of InAs quantum dots was found. The observed ODCR seems to belong to a two-dimensional system, such as a heterointerface InAs / GaAs .
ANOMALOUS ANISOTROPY OF RESONANT RAMAN SCATTERING IN OPEN ZnCdSe/ZnSe NANOWIRES
Authors: KAIBYSHEV V. H. , TRAVNIKOV V. V.
Published: June 2004

Anomalous strong linear anisotropy of resonant Raman scattering in open ZnCdSe / ZnSe nanowires has been found. The anisotropy value is more than twice as that due to the anisotropy of exciton–photon interaction which is the characteristic for open nanowires. It is suggested that the anomalous anisotropy is connected with different probability of Frohlich exciton–LO phonon interaction at scattering via transverse and longitudinal exciton states.
SPIN-CHARGE STRUCTURE OF QUANTUM WIRES COUPLED TO ELECTRON RESERVOIRS
Authors: SABLIKOV V. A. , POLYAKOV S. V.
Published: June 2004

We report the correlated charge and spin density distributions in a quantum wire coupled to electron reservoirs. It is found that charging the wire because of the electron density redistribution between the wire and reservoirs results in the increase of the critical electron density, below which the spontaneous spin polarization appears. The distributions of the electron densities with spin up and spin down along the wire have components oscillating in opposite phases with the wave vector 2kF, kF being the Fermi wave vector. As a result the antiferromagnetic spin order appears, with one of the spin components spontaneously predominating. The charge density distribution is close to the Wigner order with the small amplitude of the 4kF charge-density waves.
COULOMB INTERACTION OF TRIANGULAR QUANTUM DOTS IN A SMALL RING INTERFEROMETER
Authors: BAKSHEYEV D. G. , BYKOV A. A. , TKACHENKO V. A. , TKACHENKO O. A. , LITVIN L. V. , LATYSHEV A. V. , ASEEV A. L. , ESTIBALS O. , PORTAL J.-C.
Published: June 2004

Doublet splitting of single-electron peaks has been observed in the conductance of a small high-resistance ring interferometer. Realistic modeling of the device shows that the electron system of interferometer divides into two triangular quantum dots connected by single-mode channels to each other and to reservoirs. We explain the splitting of conductance peaks by charge interaction of the dots.
ZEEMAN EFFECT FOR ELECTRONS AND HOLES IN Ge/Si QUANTUM DOTS
Authors: NENASHEV A. V. , DVURECHENSKII A. V. , ZINOVIEVA A. F. , GOLOVINA E. A.
Published: June 2004

We investigate theoretically the Zeeman effect on the electron and hole states in quantum dots. In frame of tight-binding approach, we propose a method of calculating the g factor for localized states. The principal values of the g factor for the ground electron and hole states in the self-assembled Ge / Si quantum dot are calculated. We find the strong g factor anisotropy — the components gxx, gyy are one order smaller than the gzz component, gzz=15.71, gxx=1.14, and gyy=1.76. The analysis of the wave function structure shows that the g factor of hole are mainly controlled by the contribution of the state with Jz=±(3/2), where Jz is the angular momentum projection on the growth direction of the quantum dot. The g factor of localized electron in Ge / Si quantum dot is close to 2: gzz=2.0004 and gxx=gyy=1.9976.
EXCITONS IN SINGLE-WALL CARBON NANOTUBES
Authors: BULASHEVICH K. A. , SURIS R. A. , ROTKIN S. V.
Published: June 2004

Excitonic states in single-wall carbon nanotubes have been studied within the tight-binding approximation. An analytical expression for the dielectric function of the nanotube has been obtained in the random phase approximation. It was demonstrated that calculations with the static dielectric function yield an overestimated exciton binding energy exceeding the nanotube energy gap. Self-consistent calculation of the exciton binding energy with the frequency-dependent dielectric function has been performed. The binding energy to energy gap ratio has been shown to have no dependence on the nanotube radius and to be a universal constant ~0.87 for given resonance integral γ0=2.7 eV .
CURRENT INDUCED ENTANGLEMENT OF DOUBLE QUANTUM DOT EXCITONS
Authors: CHEN YUEH-NAN , CHUU DER-SAN
Published: June 2004

We propose to measure Purcell effect by observing the current through a semeiconductor quantum dot embedded inside a microcavity. The stationary current is shown to be altered if one varies the cavity length. For the double-dot system, we find that the stationary current shows oscillatory behavior as one varies the inter-dot distance. Furthermore, the current is suppressed if the dot distance is small compared to the wavelength of the emitted photon. This photon trapping phenomenon generates the entangled state and may be used to control the emission of single photons at predetermined times.
ARE AHARONOV–BOHM EFFECT AND QUANTIZED HALL REGIME COMPATIBLE?
Authors: CHENAUD B. , CHAUBET C. , JOUAULT B. , SAMINADAYAR L. , MAILLY D. , FAINI G. , CAVANNA A.
Published: June 2004

We present calculations of the quantum oscillations appearing in the transmission of a mesoscopic GaAs / GaAlAs ring isolated by quantum point contacts. We show that the device acts as an electronic Fabry–Perot spectrometer in the quantum Hall effect regime, and discuss the effect of the coherence length of edge states.
2DEG SPECTROSCOPY WITH RESONANT TUNNELING THROUGH SINGLE IMPURITY STATE
Authors: GRYGLAS M. , BAJ M. , JOUAULT B. , RAYMOND A. , CHAUBET C. , CHENAUD B. , ROBERT J. L. , FAINI G.
Published: June 2004

We have used silicon impurities in an aluminum arsenide barrier to probe an adjacent two-dimensional electron gas (2DEG). A single impurity acts as a local spectrometer and scans the local density of states of the 2DEG. Magnetotransport experiments have been performed at low temperature with a magnetic field B applied along the direction of the current. Current–voltage characteristics strongly depend on B and reveal the formation of Landau levels (LLs).
FERMI SURFACES OF CRYSTALS IN A HIGH MAGNETIC FIELD
Authors: BRÜNING J. , DEMIDOV V. V. , GEYLER V. A.
Published: June 2004

A method of building and investigation of the Fermi surfaces for three-dimensional crystals subjected to a uniform magnetic field is presented. The Hamiltonian of a charged particle in the crystal is treated in the framework of the zero-range potential theory. The dispersion relation for the Hamiltonian is obtained in an explicit form.
DISTRIBUTION OF EQUILIBRIUM EDGE CURRENTS
Authors: ENTIN M. V. , MAGARILL L. I. , MAHMOODIAN M. M.
Published: June 2004

The distribution of equilibrium edge current density in 2D system subjected to a strong (quantizing) magnetic field has been studied. The case of half plane in normal magnetic field has been considered. The transition from classical strong magnetic field to ultra-quantum limit has been investigated. We have shown that the edge current density oscillates and decays with distance from the edge. The oscillations have been attributed to the Fermi wavelength of electrons. The additional component of the current smoothly depending on the distance but sensitive to the occupation of Landau levels has been found. The temperature suppression of oscillations has been studied.
PSEUDO-GAP AND SPIN POLARIZATION IN A TWO-DIMENSIONAL ELECTRON GAS
Authors: VYURKOV VLADIMIR , VETROV ANDREY , RYZHII VICTOR
Published: June 2004

Tunneling (one-particle excitation) density of states in the vicinity of Fermi level of a two-dimensional electron gas (2DEG) subjected to an external parallel and zero magnetic field is calculated. It reveals a pseudo-gap recently observed in the experiments. The gap originates in spin polarization of 2DEG. Nonmonotonic dependence of energy on a Landau level filling factor (density) for perpendicular magnetic field was also obtained. It implies the tunneling current peculiarities at filling factors of about 1/2 and 1. The Ising-like model of the exchange interaction in 2DEG was exploited instead of the conventional one. It was crucial to achieve even a qualitative agreement with experimental data.
ATP-dependent transport of organic anions into isolated basolateral membrane vesicles from rat intestine
Authors: Shoji Takahiro , Suzuki Hiroshi , Kusuhara Hiroyuki , Watanabe Yuka , Sakamoto Shingo , Sugiyama Yuichi
Published: June 2004

The mechanism for the cellular extrusion of organic anions across the intestinal basolateral membrane was examined using isolated membrane vesicles from rat jejunum, ileum, and colon. It was found that 17β-estradiol 17β-d-glucuronide (E217βG) is taken up in an ATP-dependent manner into the basolateral membrane vesicles (BLMVs) but not into the brush-border or microsomal counterparts. The ATP-dependent uptake of E217βG into BLMVs from jejunum and ileum was described by a single component with a Kmvalue of 23.5 and 8.31 μM, respectively, whereas that into the BLMVs from colon was described by assuming the presence of high ( Km= 0.82 μM)- and low-affinity ( Km= 35.4 μM) components. Taurocholate, 6-hydroxy-5,7-dimethyl-2-methylamino-4-(3-pyridylmethyl) benzothiazole glucuronide and taurolithocholate sulfate, but not leukotriene C4, were significantly taken up by the BLMVs. In addition to such substrate specificity, the inhibitor sensitivity of the ATP-dependent transport in BLMVs was similar to that of rat multidrug resistance-associated protein 3 (Mrp3), which is located on the basolateral membrane of enterocytes. Together with the fact that the rank order of the extent of the expression of Mrp3 (jejunum < ileum << colon) is in parallel with that of the extent of the transport of ligands, these results suggest that the ATP-dependent uptake of organic anions into isolated intestinal BLMVs is at least partly mediated by Mrp3.
Relative contributions of NOS isoforms during experimental colitis: endothelial-derived NOS maintains mucosal integrity
Authors: Vallance Bruce A. , Dijkstra Gerard , Qiu Bosheng , van der Waaij Laurens A. , van Goor Harry , Jansen Peter L. M. , Mashimo Hiroshi , Collins Stephen M.
Published: June 2004

The role of nitric oxide (NO) in inflammatory bowel diseases has traditionally focused on the inducible form of NO synthase (iNOS). However, the constitutive endothelial (eNOS) and neuronal (nNOS) isoforms may also impact on colitis, either by contributing to the inflammation or by regulating mucosal integrity in response to noxious stimuli. To date, studies examining the roles of the NOS isoforms in experimental colitis have been conflicting, and the mechanisms by which these enzymes exert their effects remain unclear. To investigate and clarify the roles of the NOS isoforms in gut inflammation, we induced trinitrobenzenesulfonic acid colitis in eNOS, nNOS, and iNOS knockout (KO) mice, assessing the course of colitis at early and late times. Both eNOS and iNOS KO mice developed a more severe colitis compared with wild-type mice. During colitis, iNOS expression dramatically increased on epithelial and lamina propria mononuclear cells, whereas eNOS expression remained localized to endothelial cells. Electron and fluorescence microscopy identified bacteria in the ulcerated colonic mucosa of eNOS KO mice, but not in wild-type, iNOS, or nNOS KO mice. Furthermore, eNOS KO mice had fewer colonic goblet cells, impaired mucin production, and exhibited increased susceptibility to an inflammatory stimulus that was subthreshold to other mice. This susceptibility was reversible, because the NO donor isosorbide dinitrate normalized goblet cell numbers and ameliorated subsequent colitis in eNOS KO mice. These results identify a protective role for both iNOS and eNOS during colitis, with eNOS deficiency resulting in impaired intestinal defense against lumenal bacteria and increased susceptibility to colitis.