bluuebunny/crossref_metadata_2025 huggingface dataset:
HEDGE FUNDS: WHAT DO WE KNOW?
Authors: Edwards Franklin R. , Gaon Stav
Published: April 2005

Hedge funds are attracting increased attention because of their reputation for earning superior (risk‐adjusted) returns. Hedge Fund Research Inc. estimates that in 2001 there were about 7,000 hedge funds with investor capital of about $600 billion. And yet the diversity of hedge funds, combined with a general lack of transparency, makes the hedge fund industry something of a “black box.”

This article provides an overview of the legal structure of hedge funds, the various fund investment strategies, and the existing research on overall hedge fund performance. Without uniform and comprehensive reporting requirements, it is difficult to ascertain the size and scope of hedge fund investments. Nonetheless, current research provides persuasive evidence that hedge funds earn positive risk‐adjusted returns, on average, in contrast to their counterparts in the mutual fund industry. In an attempt to explain these higher returns, the authors begin by noting that hedge funds are subject to considerably less regulation than other investment institutions because their client base is limited to wealthy individuals and institutions. Hedge funds can thus employ investment strategies that mutual funds and pension funds are prohibited from pursuing, such as short selling, high leverage, derivatives, concentrated holdings, and limited redemptions. As a result, the funds may be able to earn excess returns by operating in illiquid and specialized markets where there is a shortage of arbitrage capital. At the same time, and perhaps even more important, hedge funds are in a better position than conventional mutual funds to attract skilled managers because of their use of performance‐based incentive fee structures.
PRIVATE EQUITY INVESTING IN EMERGING MARKETS
Authors: Leeds Roger , Sunderland Julie
Published: April 2005

After a proliferation of emerging market funds in the 1990s, growth has slowed drastically due to disappointing preliminary results. Private sector funds initially appeared promising because of the burgeoning demand for capital in emerging markets, the new receptivity of governments to foreign investors, and the prospect of high returns. But in many cases, the regulatory and legal frameworks did not provide adequate investor protection, and dramatic differences in accounting standards, corporate governance, and exit potential created problems. These problems are often accentuated because local owners are adept at navigating the legal and accounting systems, placing investors at a disadvantage.

As global competition intensifies, local policies, regulations, and business practices are becoming increasingly important in attracting investors. Local governments must institute the reforms necessary to improve the investment environment, including the strengthening of shareholder rights and corporate governance standards and improving access to public equity markets. Development finance institutions must provide direction and leadership in these areas. And fund managers must align their business models more closely with emerging market realities by establishing a local presence, adopting a more hands‐on approach to monitoring their investments, and developing creative exit strategies.
ECONOMICS OF CORPORATE GOVERNANCE REFORM
Authors: Kroszner Randall S.
Published: April 2005

This paper develops three basic economic principles for effective corporate governance: (1) information accuracy and timeliness, (2) management accountability, and (3) auditor independence. Accuracy and timeliness of information is critical to providing market participants with the data necessary to monitor and evaluate managers. Management accountability focuses on strengthening the incentives of managers to act in shareholders' interests and on increasing the likelihood and magnitude of punishment for wrongdoing. Auditor independence reduces the incentives and likelihood that auditors would give managers more leeway to undertake fraudulent or questionable acts.

The author provides a preliminary assessment of how well legislative reforms, such as the Sarbanes‐Oxley Act, regulatory changes at the SEC, and private sector responses such as those from self‐regulatory organizations like the NYSE and NASDAQ, conform to these economic principles. The paper concludes by commenting on current proposals from the SEC on “shareholder democracy” and emphasizing the importance of balancing private and public regulatory responses.
Control Premiums and the Effectiveness of Corporate Governance Systems
Authors: Dyck Alexander , Zingales Luigi
Published: April 2005

This article summarizes the findings of the authors' study, published recently in the Journal of Finance, that use control premiums paid in large block sales to assess the quality of corporate governance systems. The authors report significant variation in such premiums, with countries like the U.S. and U.K. showing premiums of less than 10% while premiums for countries like Brazil running in excess of 60%.

The study also uses these measures to determine which institutions tend to be most effective in helping minority shareholders limit the diversion of wealth by insider or controlling shareholders. Notable among such institutional variables are better accounting standards, legal protection of minority shareholders, and law enforcement. But the authors also emphasize the importance of a number of extra‐legal factors, including more intense product market competition, diffusion of an independent press, and a high rate of tax compliance.
DOES INTERNATIONAL FINANCIAL CONTAGION REALLY EXIST?
Authors: Karolyi G. Andrew
Published: April 2005

In the 1990s, exchange rate crises followed stock market crashes and sharp economic contractions, with devastating effects on countries around the world. The frequency and extent of these events led many policymakers, regulators, journalists, and market participants to declare a “crisis of global capitalism” and to call for a new “international financial architecture.” When financial crises occur in neighboring countries in rapid succession, it is tempting to believe that financial distress is capable of spreading like a contagious disease. Moreover, it is logical to look for potential carriers of such a disease among market participants such as commercial banks, international mutual funds, and global investors.

The problem, however, is that much of the evidence does not support the idea of international financial contagion. This article surveys and synthesizes the empirical evidence on international asset price co‐movements, the volatility of cross‐border capital flows, and the relationship between those flows and asset prices. A careful reading of this evidence suggests that the observed co‐movements during the 1990s might not have been excessively large, given the global economic and capital market environment. As the author suggests, the appearance of what some might call contagion could instead be attributed to errors in domestic financial policies that have simply been repeated many times by affected countries in response to common economic shocks. And this in turn implies that while the various reform proposals to date have been directed mainly at the international and supra‐national level—involving questions such as the appropriate exchange rate and international financial market regimes, and how to organize the IMF and the World Bank group of the future–the most important questions may be those concerning government policy at the national level. Fiscal and monetary policymakers may need to rethink how their governments regulate access to the domestic financial sector, how their markets are supervised by the central bank, and how such supervision can be used to improve risk management for the financial service sector.
Identification of Novel Subgenomic RNAs and Noncanonical Transcription Initiation Signals of Severe Acute Respiratory Syndrome Coronavirus
Authors: Hussain Snawar , Pan Ji'an , Chen Yu , Yang Yalin , Xu Jing , Peng Yu , Wu Ying , Li Zhaoyang , Zhu Ying , Tien Po , Guo Deyin
Published: April 2005

The expression of the genomic information of severe acute respiratory syndrome coronavirus (SARS CoV) involves synthesis of a nested set of subgenomic RNAs (sgRNAs) by discontinuous transcription. In SARS CoV-infected cells, 10 sgRNAs, including 2 novel ones, were identified, which were predicted to be functional in the expression of 12 open reading frames located in the 3′ one-third of the genome. Surprisingly, one new sgRNA could lead to production of a truncated spike protein. Sequence analysis of the leader-body fusion sites of each sgRNA showed that the junction sequences and the corresponding transcription-regulatory sequence (TRS) are unique for each species of sgRNA and are consistent after virus passages. For the two novel sgRNAs, each used a variant of the TRS that has one nucleotide mismatch in the conserved hexanucleotide core (ACGAAC) in the TRS. Coexistence of both plus and minus strands of SARS CoV sgRNAs and evidence for derivation of the sgRNA core sequence from the body core sequence favor the model of discontinuous transcription during minus-strand synthesis. Moreover, one rare species of sgRNA has the junction sequence AAA, indicating that its transcription could result from a noncanonical transcription signal. Taken together, these results provide more insight into the molecular mechanisms of genome expression and subgenomic transcription of SARS CoV.
Structure and Assembly of a
T
=1 Virus-Like Particle in BK Polyomavirus
Authors: Nilsson Josefina , Miyazaki Naoyuki , Xing Li , Wu Bomu , Hammar Lena , Li Tian Cheng , Takeda Naokazu , Miyamura Tatsuo , Cheng R. Holland
Published: April 2005

In polyomaviruses the pentameric capsomers are interlinked by the long C-terminal arm of the structural protein VP1. The
T
=7 icosahedral structure of these viruses is possible due to an intriguing adaptability of this linker arm to the different local environments in the capsid. To explore the assembly process, we have compared the structure of two virus-like particles (VLPs) formed, as we found, in a calcium-dependent manner by the VP1 protein of human polyomavirus BK. The structures were determined using electron cryomicroscopy (cryo-EM), and the three-dimensional reconstructions were interpreted by atomic modeling. In the small VP1 particle, 26.4 nm in diameter, the pentameric capsomers form an icosahedral
T
=1 surface lattice with meeting densities at the threefold axes that interlinked three capsomers. In the larger particle, 50.6 nm in diameter, the capsomers form a
T
=7 icosahedral shell with three unique contacts. A folding model of the BKV VP1 protein was obtained by alignment with the VP1 protein of simian virus 40 (SV40). The model fitted well into the cryo-EM density of the
T
=7 particle. However, residues 297 to 362 of the C-terminal arm had to be remodeled to accommodate the higher curvature of the
T
=1 particle. The loops, before and after the C-terminal short helix, were shown to provide the hinges that allowed curvature variation in the particle shell. The meeting densities seen at the threefold axes in the
T
=1 particle were consistent with the triple-helix interlinking contact at the local threefold axes in the
T
=7 structure.
Replication-Competent Adenovirus Formation in 293 Cells: the Recombination-Based Rate Is Influenced by Structure and Location of the Transgene Cassette and Not Increased by Overproduction of HsRad51, Rad51-Interacting, or E2F Family Proteins
Authors: Duigou Gregory J. , Young C. S. H.
Published: April 2005

Propagation of E1 region replacement adenovirus vectors in 293 cells results in the rare appearance of replication-competent adenovirus (RCA). The RCA genome contains E1 DNA acquired from the 293 cellular genome. The Luria-Delbrück fluctuation test was adapted to measure RCA formation rates. To test if structure affected rate, we measured rates during the production of adenovirus vectors with genomes containing three different expression cassette arrangements. The vectors had different extents of sequence identity with integrated Ad5 DNA of 293 cells and had different distributions of identity flanking the expression cassettes. Empty cassette vector RCA rates ranged from 2.5 × 10
−8
to 5.6 × 10
−10
. The extent of sequence identity was not an accurate RCA rate predictor. The vector with the highest RCA rate also had the least overall sequence identity. To define factors controlling RCA generation, adenovirus vectors expressing E2F family proteins, known to modulate recombination gene expression, and overexpressing the human Rad51 recombination protein were analyzed. Compared to their corresponding empty vectors, RCA rates were not increased but were slightly decreased. Initial results suggested expression cassette orientation and/or transcription direction as potential RCA rate modifiers. Testing adenovirus vectors with identical transgene cassettes oriented in opposite directions suggested that transcription direction was not the basis of these rate differences. Thus, the overall structure and location of the transgene cassette had the largest effect on RCA rate. The RCA fluctuation test should be useful for investigators who require accurate measurements of targeted recombination and the probability of RCA formation during stock production.
Linked Tumor-Selective Virus Replication and Transgene Expression from E3-Containing Oncolytic Adenoviruses
Authors: Zhu Mingzhu , Bristol J. Andrew , Xie Yuefeng , Mina Mervat , Ji Hong , Forry-Schaudies Suzanne , Ennist David L.
Published: April 2005

Historically, the adenoviral E3 region was found to be nonessential for viral replication in vitro. In addition, adenoviruses whose genome was more than approximately 105% the size of the native genome were inefficiently packaged. These profound observations were used experimentally to insert transgenes into the adenoviral backbone. More recently, however, the reintroduction of the E3 region into oncolytic adenoviruses has been found to positively influence antitumor efficacy in preclinical models and clinical trials. In the studies reported here, the granulocyte-macrophage colony-stimulating factor (GM-CSF) cDNA sequence has been substituted for the E3-gp19 gene in oncolytic adenoviruses that otherwise retained the E3 region. Five viruses that differed slightly in the method of transgene insertion were generated and compared to Ar6pAE2fGmF (E2F/GM/ΔE3), a previously described E3-deleted oncolytic adenovirus encoding GM-CSF. In all of the viruses, the human E2F-1 promoter regulated E1A expression and GM-CSF expression was under the control of the adenoviral E3 promoter and the packaging signal was relocated immediately upstream from the right terminal repeat. The E3-gp19-deleted viruses had similar cytolytic properties, as measured in vitro by cytotoxicity assays, but differed markedly in their capacity to express and secrete GM-CSF. Ar15pAE2fGmF (E2F/GM/E3b), the virus that produced the highest levels of GM-CSF and retained the native GM-CSF leader sequence, was selected for further analysis. The E2F/GM/E3b and E2F/GM/ΔE3 viruses exhibited similar cytotoxic activity and GM-CSF production in several tumor cell lines in vitro. However, when compared in vivo in nude mouse xenograft tumor models, E2F/GM/E3b spread through tumors to a greater extent, resulted in higher peak GM-CSF and total exposure levels in both tumor and serum, and was more efficacious than the E3-deleted virus. Using the matched WI-38 (parental) and WI-38-VA13 (simian virus 40 large T antigen transformed) cell pair, GM-CSF was shown to be selectively produced in cells expressing high levels of E2F, indicating that the tumor-selective E2F promoter controlled E1A and GM-CSF expression.
Inhibition of Toll-Like Receptor 7- and 9-Mediated Alpha/Beta Interferon Production in Human Plasmacytoid Dendritic Cells by Respiratory Syncytial Virus and Measles Virus
Authors: Schlender Jörg , Hornung Veit , Finke Stefan , Günthner-Biller Margit , Marozin Sabrina , Brzózka Krzysztof , Moghim Sharareh , Endres Stefan , Hartmann Gunther , Conzelmann Karl-Klaus
Published: April 2005

Human plasmacytoid dendritic cells (PDC) are key sentinels alerting both innate and adaptive immune responses through production of huge amounts of alpha/beta interferon (IFN). IFN induction in PDC is triggered by outside-in signal transduction pathways through Toll-like receptor 7 (TLR7) and TLR9 as well as by recognition of cytosolic virus-specific patterns. TLR7 and TLR9 ligands include single-stranded RNA and CpG-rich DNA, respectively, as well as synthetic derivatives thereof which are being evaluated as therapeutic immune modulators promoting Th1 immune responses. Here, we identify the first viruses able to block IFN production by PDC. Both TLR-dependent and -independent IFN responses are abolished in human PDC infected with clinical isolates of respiratory syncytial virus (RSV), RSV strain A2, and measles virus Schwarz, in contrast to RSV strain Long, which we previously identified as a potent IFN inducer in human PDC (Hornung et al., J. Immunol.
173:
5935-5943, 2004). Notably, IFN synthesis of PDC activated by the TLR7 and TLR9 agonists resiquimod (R848) and CpG oligodeoxynucleotide 2216 is switched off by subsequent infection by RSV A2 and measles virus. The capacity of RSV and measles virus of human PDC to shut down IFN production should contribute to the characteristic features of these viruses, such as Th2-biased immune pathology, immune suppression, and superinfection.
Novel Macula-Like Virus Identified in
Bombyx mori
Cultured Cells
Authors: Katsuma Susumu , Tanaka Shinichiro , Omuro Naoko , Takabuchi Lisa , Daimon Takaaki , Imanishi Shigeo , Yamashita Shuichi , Iwanaga Masashi , Mita Kazuei , Maeda Susumu , Kobayashi Masahiko , Shimada Toru
Published: April 2005

We identified a novel, 6,513-bp-long RNA, termed
Bombyx mori
macula-like latent virus (BmMLV) RNA, which abundantly expressed in
B. mori
cultured BmN cells. BmMLV RNA potentially encodes two proteins, putative RNA replicase and coat protein, which share structural features and sequence similarities with those of a plant RNA virus, the genus
Maculavirus
. Northern blot analysis showed that two transcripts were expressed in BmN cells: a 6.5-kb-long RNA, which contains both putative RNA replicase and coat protein genes, and a 1.2-kb-long RNA, which contains only a coat protein gene. Southern blot analysis showed that BmMLV RNA is not carried by the
B. mori
genome. RT-PCR analysis also revealed the presence of BmMLV RNA in several
B. mori
cell lines other than BmN cells, suggesting that BmMLV RNA latently exists in
B. mori
cultured cells. Infection studies showed that BmMLV virions were able to infect BmMLV-negative
Spodoptera frugiperda
Sf-9 cells and
B. mori
larvae. Electron microscopy and Northern blot analysis of a purified BmMLV revealed that isometric virions appear to be 28 to 30 nm in diameter and contain a 6.5-kb genomic RNA. These results showed that BmMLV is a novel macula-like virus infectious to and replicable in
B. mori
-derived cells.
Macrophage Inflammatory Protein 1α Inhibits Postentry Steps of Human Immunodeficiency Virus Type 1 Infection via Suppression of Intracellular Cyclic AMP
Authors: Amella Carol-Ann , Sherry Barbara , Shepp David H. , Schmidtmayerova Helena
Published: April 2005

Primary isolates of human immunodeficiency virus type 1 (HIV-1) predominantly use chemokine receptor CCR5 to enter target cells. The natural ligands of CCR5, the β-chemokines macrophage inflammatory protein 1α (MIP-1α), MIP-1β, and RANTES, interfere with HIV-1 binding to CCR5 receptors and decrease the amount of virions entering cells. Although the inhibition of HIV-1 entry by β-chemokines is well documented, their effects on postentry steps of the viral life cycle and on host cell components that control the outcome of infection after viral entry are not well defined. Here, we show that all three β-chemokines, and MIP-1α in particular, inhibit postentry steps of the HIV-1 life cycle in primary lymphocytes, presumably via suppression of intracellular levels of cyclic AMP (cAMP). Productive HIV-1 infection of primary lymphocytes requires cellular activation. Cell activation increases intracellular cAMP, which is required for efficient synthesis of proviral DNA during early steps of viral infection. Binding of MIP-1α to cognate receptors decreases activation-induced intracellular cAMP levels through the activation of inhibitory G proteins. Furthermore, inhibition of one of the downstream targets of cAMP, cAMP-dependent PKA, significantly inhibits synthesis of HIV-1-specific DNA without affecting virus entry. These data reveal that β-chemokine-mediated inhibition of virus replication in primary lymphocytes combines inhibitory effects at the entry and postentry levels and imply the involvement of β-chemokine-induced signaling in postentry inhibition of HIV-1 infection.
Cell Cycle Arrest in G
2
/M Promotes Early Steps of Infection by Human Immunodeficiency Virus
Authors: Groschel Bettina , Bushman Frederic
Published: April 2005

We have identified four small molecules that boost transduction of cells by human immunodeficiency virus (HIV) and investigated their mechanism of action. These molecules include etoposide and camptothecin, which induce DNA damage by inhibiting religation of cleaved topoisomerase-DNA complexes, taxol, which interferes with the function of microtubules, and aphidicolin, which inhibits DNA polymerases. All four compounds arrest the cell cycle at G
2
/M, though in addition high concentrations of aphidicolin arrest in G
1
. We find that early events of HIV replication, including synthesis of late reverse transcription products, two-long terminal repeat circles, and integrated proviruses, were increased after treatment of cells with concentrations of each compound that arrested in G
2
/M. Stimulation was seen for both transformed cell lines (293T and HeLa cells) and primary cells (IMR90 lung fibroblasts). Arrest in G
1
with high concentrations of aphidicolin boosted transduction, though not much as with lower concentrations that arrested in G
2
/M. Arrest of IMR90 cells in G
1
by serum starvation and contact inhibition reduced transduction. Previously, the proteasome inhibitor MG132 was reported to increase HIV infection—here we investigated the effects of combinations of the cell cycle inhibitors with MG132 and obtained data suggesting that MG132 may also boost transduction by causing G
2
/M cell cycle arrest. These data document that cell cycle arrest in G
2
/M boosts the early steps of HIV infection and suggests methods for increasing transduction with HIV-based vectors.
Evaluation of the Conformational Switch Model for Alfalfa Mosaic Virus RNA Replication
Authors: Petrillo Jessica E. , Rocheleau Gail , Kelley-Clarke Brenna , Gehrke Lee
Published: April 2005

Key elements of the conformational switch model describing regulation of alfalfa mosaic virus (AMV) replication (R. C. Olsthoorn, S. Mertens, F. T. Brederode, and J. F. Bol, EMBO J. 18:4856-4864, 1999) have been tested using biochemical assays and functional studies in nontransgenic protoplasts. Although comparative sequence analysis suggests that the 3′ untranslated regions of AMV and ilarvirus RNAs have the potential to fold into pseudoknots, we were unable to confirm that a proposed pseudoknot forms or has a functional role in regulating coat protein-RNA binding or viral RNA replication. Published work has suggested that the pseudoknot is part of a tRNA-like structure (TLS); however, we argue that the canonical sequence and functional features that define the TLS are absent. We suggest here that the absence of the TLS correlates directly with the distinctive requirement for coat protein to activate replication in these viruses. Experimental data are evidence that elevated magnesium concentrations proposed to stabilize the pseudoknot structure do not block coat protein binding. Additionally, covarying nucleotide changes proposed to reestablish pseudoknot pairings do not rescue replication. Furthermore, as described in the accompanying paper (L. M. Guogas, S. M. Laforest, and L. Gehrke, J. Virol. 79:5752-5761, 2005), coat protein is not, by definition, inhibitory to minus-strand RNA synthesis. Rather, the activation of viral RNA replication by coat protein is shown to be concentration dependent. We describe the 3′ organization model as an alternate model of AMV replication that offers an improved fit to the available data.
Rhesus Cytomegalovirus Contains Functional Homologues of US2, US3, US6, and US11
Authors: Pande Nupur T. , Powers Colin , Ahn Kwangseog , Früh Klaus
Published: April 2005

Human cytomegalovirus (HCMV) is a paradigm for mechanisms subverting antigen presentation by major histocompatibility complex (MHC) molecules. Due to its limited host range, HCMV cannot be studied in animals. Thus, the in vivo importance of inhibiting antigen presentation for the establishment and maintenance of infection with HCMV is unknown. Rhesus cytomegalovirus (RhCMV) is an emerging animal model that shares many of the features of HCMV infection. The recent completion of the genomic sequence of RhCMV revealed a significant degree of homology to HCMV. Strikingly, RhCMV contains several genes with low homology to the HCMV US6 gene family of inhibitors of the MHC I antigen presentation pathway. Here, we examine whether the RhCMV US6 homologues (open reading frames Rh182, -184, -185, -186, -187, and -189) interfere with the MHC I antigen-processing pathway. We demonstrate that Rh182 and Rh189 function similarly to HCMV US2 and US11, respectively, mediating the proteasomal degradation of newly synthesized MHC I. The US3 homologue, Rh184, delayed MHC I maturation. Unlike US3, MHC I molecules eventually escaped retention by Rh184, so that steady-state surface levels of MHC I remained unchanged. Rh185 acted similarly to US6 and inhibited peptide transport by TAP and, consequently, peptide loading of MHC I molecules. Thus, despite relatively low sequence conservation, US6 family-related genes in RhCMV are functionally closely related to the conserved structural features of HCMV immunomodulators. The conservation of these mechanisms implies their importance for immune evasion in vivo, a question that can now be addressed experimentally.
QUANTUM STATES OF A GENERALIZED PENDULUM UNDER TIME-DEPENDENT GRAVITATION
Authors: PEDROSA I. A. , GUEDES I.
Published: April 2005

We obtain the Schrödinger wave functions of a generalized pendulum under time-dependent gravitation by making use of the Lewis and Riesenfeld invariant method. As an example, we consider a generalized pendulum with constant gravitation and exponentially increasing mass. We also present a canonical approach to the generalized time-dependent pendulum.
THE EFFECTS OF NONSTANDARD Z COUPLINGS ON THE LEPTON POLARIZATIONS IN Bs→γℓ+ℓ-DECAYS
Authors: TURAN GÜRSEVIL
Published: April 2005

The fact that the measured B→ππ, πK branching ratios exhibit puzzling patterns has received a lot of attention in the literature and motivated the formulation of a series of new physics scenarios with enhanced Z-penguins. Here, we analyze the effect of such an enhancement on the lepton polarization asymmetries of Bs→γℓ+ℓ-decays by applying the results of a specific scenario for the solution of "B→πK puzzle".
CAN LIGHTCONE FLUCTUATIONS BE PROBED WITH COSMOLOGICAL BACKGROUNDS?
Authors: POLARSKI DAVID , ROCHE PHILIPPE
Published: April 2005

Finding signatures of quantum gravity in cosmological observations is now actively pursued both from the theoretical and the experimental side. Recent work has concentrated on finding signatures of light-cone fluctuations in the CMB. Because in inflationary scenarios a Gravitational Wave Background (GWB) is always emitted much before the CMB, we can ask, in the hypothesis where this GWB could be observed, what is the imprint of light cone fluctuations on this GWB. We show that due to the flat nature of the GWB spectrum, the effect of lightcone fluctuations are negligible.
OSCILLATORY AND VANISHING RESISTANCE STATES IN MICROWAVE IRRADIATED 2D ELECTRON SYSTEMS
Authors: DU R. R. , ZUDOV M. A. , YANG C. L. , YUAN Z. Q. , PFEIFFER L. N. , WEST K. W.
Published: April 2005

Giant-amplitude oscillations in dc magnetoresistance of a high-mobility two-dimensional electron system can be induced by millimeterwave irradiations, leading to zero-resistance states at the oscillation minima. Following a brief overview of the now well-known phenomenon, this paper reports on aspects of more recent experiments on the subject. These are: new zero-resistance states associated with multi-photon processes; suppression of Shubnikov-de Haas oscillations by high-frequency microwaves; and microwave photoconductivity of a high-mobility two-dimensional hole system.
TUNNELING BETWEEN TWO QUANTUM HALL DROPLETS
Authors: YANG INSEOK , KANG WOOWON , PFEIFFER LOREN , BALDWIN KIRK , WEST KEN
Published: April 2005

We report on tunneling experiment between two quantum Hall droplets separated by a nearly ideal tunnel barrier. The device is produced by cleaved edge overgrowth that laterally juxtaposes two two-dimensional electron systems across a high quality semi-conductor barrier. The dramatic evolution of the tunneling characteristics is consistent with the magnetic field-dependent tunneling between the coupled edge states of the quantum Hall droplets. We identify a series of quantum critical points between successive strong and weak tunneling regimes that are reminiscent of the plateau-transitions in quantum Hall effect. Scaling analysis shows that the conductance near the critical magnetic fields Bc is a function of a single scaling argument |B-Bc|T-κ, where the exponent κ=0.42. This puzzling resemblance to a quantum Hall-insulator transition points to the significance of interedge correlation in the lateral tunneling of quantum Hall droplets.
THE TWO-FLUX COMPOSITE FERMION SERIES OF FRACTIONAL QUANTUM HALL STATES IN STRAINED (100) Si
Authors: LAI K. , PAN W. , TSUI D. C. , LYON S. , MUHLBERGER M. , SCHAFFLER F.
Published: April 2005

Magnetotransport properties are studied in a high-mobility 2DES in the strained Si quantum well. We observe around ν=1/2 the two-flux composite fermion ( CF 2) series of the FQHE states at ν=2/3, 3/5, 4/7, and at ν=4/9, 2/5, 1/3. Of the CF series, the ν=3/5 state is weaker than the nearby 4/7 state and the 3/7 state is missing, resembling the observation that the ν=3 is weaker than the ν=4 state. Our data indicate that the CF model still applies for the multivalley Si / SiGe system when taking into account the two-fold valley degeneracy.
SECOND GENERATION OF COMPOSITE FERMIONS AND THE SELF-SIMILARITY OF THE FRACTIONAL QUANTUM HALL EFFECT
Authors: GOERBIG M. O. , LEDERER P. , SMITH C. MORAIS
Published: April 2005

A recently developed model of interacting composite fermions, is used to investigate different composite-fermion phases. Their interaction potential allows for the formation of both solid and new quantum-liquid phases, which are interpreted in terms of second-generation composite fermions and which may be responsible for the fractional quantum Hall states observed at unusual filling factors, such as ν=4/11. Projection of the composite-fermion dynamics to a single level, involved in the derivation of the Hamiltonian of interacting composite fermions, reveals the underlying self-similarity of the model.
RESISTANCE SPIKES INDUCED BY GATE-CONTROLLED VALLEY-SPLITTING IN SILICON
Authors: TAKASHINA K. , FUJIWARA A. , TAKAHASHI Y. , HIRAYAMA Y.
Published: April 2005

Landau-level coincidences are examined in a (100) silicon 2DEG by tuning the valley-splitting with front- and back-gates. A coincidence under quantum Hall conditions between levels of opposite spin, opposite valley, but like orbital indices at ν=6 is found to show suppressed resistance, while in marked contrast, coincidences at ν=4i (where i is an integer) between adjacent orbital Landau levels exhibit resistance spikes.
MAGNETOTRANSPORT IN DILUTE 2D SI-MOSFET SYSTEM
Authors: CHEREMISIN M. V.
Published: April 2005

The beating pattern of Shubnikov-de Haas oscillations is reproduced in crossed magnetic field configuration and in presence of zero-field valley splitting in Si -MOSFET 2D system. The features of Quantum Hall Effect in extremely dilute 2D system are discussed.
DISORDER INDUCED COHERENCE-INCOHERENCE CROSSOVER IN RANDOM GaAs/AlGaAs SUPERLATTICES
Authors: PUSEP Y. A. , RIBEIRO M. B. , ARAKAKI H. , DE SOUZA C. A. , MALZER S. , DÖHLER G. H.
Published: April 2005

The coherence of electrons was studied in intentionally disordered GaAs / AlGaAs superlattices as a function of the vertical interlayer coupling. Depending on the relation of the disorder energy and the Fermi energy the coherent and incoherent diffusive transport regimes were distinguished. New features of weakly coupled layered electron systems such as the vertical coupling energy and the in-plane phase-breaking time were observed by magnetoresistance measurements in the coherent and incoherent regimes respectively. Both of them were found to decrease with increasing disorder strength. This demonstrates the disorder induced break-down of the interlayer coherence of quasi-particles which drastically affected their intralayer coherence.
TUNNELING BETWEEN SPIN POLARIZED EDGE STATES STUDIED AT HIGH MAGNETIC FIELDS
Authors: SUKHODUB G. , HOHLS F. , HAUG R. J. , MAUDE D. K. , REUTER D. , WIECK A. D.
Published: April 2005

We utilize the tunneling between edge states of the lowest Landau level to study the behavior of the spin splitting in a wide range of magnetic fields up to 28 T. We find that the Zeeman energy with the bare |g*|=0.44 of GaAs mainly accounts for the observed threshold in the bias voltage between edge states. There is no evidence for the exchange interaction considerably affecting the measured energy gaps at the edge of a two-dimensional electron system.
DESTRUCTION OF CORRELATED BILAYER STATES SUBJECTED TO TILTED MAGNETIC FIELDS
Authors: ZEITLER U. , DE JONGE J. , VAN TILBURG J. W. W. , MAAN J. C. , REUTER D. , WIECK A. D.
Published: April 2005

We use tilted magnetic fields to effectively decouple a strongly coupled bilayer two-dimensional electron system into two separate layers. For our specific sample (tunnelling gap ΔSAS=2.5 meV ) the inter-layer coupling is quenched by an in-plane field B≈14 T , leading to the successive disappearance of all odd-integer states visible in the quantum Hall effect. Such a transition from a bilayer into two single layers is also observed in a solely parallel magnetic field. Surprisingly, the ν=1 the quantum Hall state remains present even for in-plane fields exceeding 20 T. Only when decreasing the total Landau level filling slightly below ν=1 the system undergoes an abrupt transition from a ν=1 quantum Hall state into two (insulating) systems with a half filled Landau level.
ANISOTROPIC TRANSPORT ON THE ν=1 BILAYER QUANTUM HALL SYSTEM UNDER TILTED MAGNETIC FIELD
Authors: MORINO M. , IWATA K. , SUZUKI M. , EZAWA Z. F. , FUKUDA A. , SAWADA A. , SAKU T. , KUMADA N. , MURAKI K. , HIRAYAMA Y.
Published: April 2005

We measured an anisotropic magnetotransport that depends on directions of an in-plane field in a bilayer quantum Hall system. We found that the longitudinal resistance near the bilayer ν=1 quantum Hall state strongly varies when we changed an relative angle between the current and the in-plane field. It is a phenomenon peculiar to the bilayer ν=1 quantum Hall state, because this phenomenon does not appear in a monolayer system.
NEAR FIELD SPECTROSCOPY OF QUANTUM DOTS UNDER MAGNETIC FIELD
Authors: ZORA ANNA , SIMSERIDES CONSTANTINOS , TRIBERIS GEORGIOS
Published: April 2005

We present the basic steps for the study of the linear near field absorption spectra of semiconductor quantum dots under magnetic field of variable orientation. We show that the application of the magnetic field alone is sufficient to induce -increasing the spot illuminated by the near field probe- interesting features to the absorption spectra.
TUNNELING BETWEEN BILAYER QUANTUM HALL STRUCTURES IN A STRONG MAGNETIC FIELD
Authors: KLIRONOMOS F. D. , DORSEY A. T.
Published: April 2005

We calculate the tunneling current in a quantum Hall bilayer system in the strong magnetic field limit. We model the bilayer electron system as two Wigner crystals coupled through interlayer Coulomb interactions, treated in the continuum limit. We generalized the Johansson and Kinaret (JK) model? and were able to study the effect of the low energy out-of-phase magnetophonon modes produced as a result of tunneling events. We find the same scaling behavior of the tunneling current peak with the magnetic field as found by JK but were able to find the tunneling current scaling behavior with interlayer distance as well.
MAGNETIZATION OF DIGITALLY Mn-DOPED DILUTED MAGNETIC SEMICONDUCTOR QUANTUM WELLS
Authors: KIM H. J. , YI K. S.
Published: April 2005

We present spin-resolved electronic properties of digitally Mn -doped diluted magnetic semiconductor (DMS) quantum wells (QWs) with an emphasis on the control of spontaneous magnetization and spin carrier distributions in terms of QW structure parameters and doping profiles of the magnetic ions. A combined Schrödinger and Poisson equation is solved numerically to obtain self-consistent subband wavefunctions and energies of the holes in the DMS QWs. Self-consistent spin-resolved subband structure shows that (i) the spatial distributions of the majority and minority spin carriers are separated in the DMS QW below the Curie temperature and (ii) the spontaneous magnetization of the Mn -doped magnetic nanostructure depends sensitively on doping profiles of the magnetic ion and the strength of exchange couplings.
MAGNETO-PHOTOLUMINESCENCE STUDY AT A FRACTIONAL QUANTUM HALL REGIME OF CHARGED EXCITONS IN A DILUTE MAGNETIC SEMICONDUCTOR
Authors: HIRAYAMA Y. , OTO K. , MINO H. , UCHIDA K. , TAKEYAMA S. , KARCZEWSKI G. , WOJTOWICZ T. , KOSSUT J.
Published: April 2005

We have performed magneto-photoluminescence measurements on modulation doped n-type Cd 1-x Mn x Te / Cd 1-y Mg y Te single quantum wells. In low magnetic fields (the electrons filling factor ν>1), we observed several photoluminescence lines associated with spin-singlet and spin-triplet charged excitons. In high magnetic fields (ν<1), we observed only one of the spin-triplet charged excitons that are called as a bright type due to characteristic spin states of electrons and holes in dilute magnetic semiconductor quantum wells, where the photoluminescence intensity increased at a fractional value of [Formula: see text]. We consider that the screening effect plays a crucial role for this behavior in high magnetic fields.
BULK NONPARABOLIC EFFECTIVE MASS APPLIED TO CALCULATION OF LANDAU LEVEL ENERGY AND COMPARISON WITH CYCLOTRON RESONANCE IN InGaAs/InAlAs QUANTUM WELLS
Authors: KOTERA NOBUO , TANAKA KOICHI , MIURA NOBORU
Published: April 2005

Observation of band nonparabolicity is difficult because the electron energy in conduction band cannot be controlled widely. Using quantization energy in quantum well (QW) where the eigen energy is changed by QW thickness, nonparabolic effective mass inside a single QW of InGaAs was determined recently, up to 0.5 eV above bandedge. The dependence of effective mass on energy was analyzed and applied to calculate Landau level energy. Calculation fit well with cyclotron resonance experiments. Coupling between skew and normal cyclotron resonance was identified by this analysis.
DEVELOPMENT OF A PLASTIC DIAMOND ANVIL CELL FOR HIGH PRESSURE MAGNETO-PHOTOLUMINESCENCE IN PULSED HIGH MAGNETIC FIELDS
Authors: MATSUDA Y. H. , UCHIDA K. , ONO K. , JI ZIWU , TAKEYAMA S.
Published: April 2005

A diamond anvil cell (DAC) made of reinforced plastic has been developed for magneto-photoluminescence experiments in pulsed high magnetic fields. Our DAC has a standard and simple structure equipped with a stainless steel gasket. We have made magneto-photoluminescence experiments of CdTe / Cd 0.8 Mn 0.2 Te multiple quantum wells up to 41 T at 4.2 K in the pressure range 0 to 2.3 GPa. We found that the effect of the eddy current heating of the gasket can be negligible small when we use the pulsed field whose duration is a few tens of milliseconds or longer. We have also found that the exciton Zeeman shift strongly depends on the pressure, which can be a manifestation of the enhancement of the sp-d and d-d exchange interactions in the Gd 0.8 Mn 0.2 Te layer by applying high pressures.
PHONON EXCITATIONS OF COMPOSITE FERMION LANDAU LEVELS
Authors: SCHULZE-WISCHELER F. , HOHLS F. , ZEITLER U. , REUTER D. , WIECK A. D. , HAUG R. J.
Published: April 2005

Energy gaps in the fractional quantum Hall regime are measured with phonon spectroscopy for various electron densities and filling factors ν=1/3, 2/5, 4/7, 3/5, 2/3, 4/3, and 5/3. At a given filling factor nearly all gaps measured show a square-root dependence on the magnetic field. The measured gaps can be described well with composite fermion theory: They are transitions between composite fermion Landau levels that are not affected by disorder on phonon wavelength. All transitions can be described by one single fit parameter related to the composite fermion effective mass. In contrast, the gaps at filling factor ν=2/3 in the high fields regime show a linear field dependence. This hints onto an only partially polarized ground state of 2/3.
EFFECT OF MUSCLES ACTIVATION ON HEAD-NECK COMPLEX UNDER SIMULATED EJECTION
Authors: Teo Ee-Chon , Zhang Qing-Hang , Tan Kian-Wee , Lee Vee-Sin
Published: April 2005

A detailed three-dimensional head-neck (C0–C7) finite element (FE) model developed based on the actual geometry of an embalmed human cadaver specimen was exercised to dictate the motions of the cervical spine under dynamic loadings. The predicted results analyzed under vertex drop impact were compared against experimental study to validate the FE model. The validated C0–C7 FE model was then further analyzed to investigate the response of the whole head-neck complex under 10G-ejection condition. From the simulation of ejection process, obvious hyper-flexion of the head-neck complex could be found. The peak flexion angles of all the lower motion segments were beyond physiological tolerance indicating a potential injury in these regions. Furthermore, the stress values in the spine were also related to the magnitudes of rotation of the motion segments. During the acceleration onset stage, the maximum stresses in the bone components were low. After that, the stress values increased sharply into the dangerous range with increased rotational angles. The effect of muscles in alleviating the potential damage in the neck is significant. It was implied that it is important for pilots to stiffen the neck before ejection to avoid severe cervical injury.
ASSESSMENT OF THREE-DIMENSIONAL ARCHITECTURE OF COLLAGEN FIBERS IN THE SUPERFICIAL ZONE OF BOVINE ARTICULAR CARTILAGE
Authors: Wu J. P. , Kirk T. B. , Zheng M. H.
Published: April 2005

The aim of this study is to investigate the structure and the collagen matrix of the superficial zone of articular cartilage using a 3D imaging technique. The split line thought to represent the orientation of the collagen fibres in the superficial zone was found using Hultkrantz's method. A semitransparent membrane was physically peeled off from the most superficial surface of bovine articular cartilage. Using fibre optic laser scanning confocal microscopy, the collagen matrix in normal cartilage, the membrane and the cartilage with the membrane peeled off were studied. The superficial zone was found to contain a more sophisticated 3D collagenous matrix than previously reported. The collagen matrix in the membrane consists of interwoven long collagen bundles, and the collagen fibres immediately subjacent to it align spatially in a predominantly oblique direction to the articular surface. The split line does not represent the orientation of the collagen in the membrane. This study presents a 3D visualization technique for a minimal-invasive examination of the 3D architecture of the collagen fibres in the superficial zone of articular cartilage, and offers a new insight into the 3D structure of the collagen matrix in the superficial zone of native cartilage.
ULTRASONOGRAPHIC DIAGNOSIS IN THE EVALUATION OF SHOULDER PAIN
Authors: Blankstein Alexander , Mirovski Yigal , Givon Uri , Chechick Aharon , Adunsky Abraham , Ganel Avraham
Published: April 2005

The benefit of adding sonography to the examination of patients suffering from shoulder pain, was examined in this retrospective evaluation. A patient suffering from shoulder pain consults generally his family physician, who sends his patient first to a radiography and not to sonography.

In 75% of the patients examined by sonography, shoulder lesions were diagnosed, demonstrated in only 33% of radiographs. Most patients had more than one lesion: 38% had partial or full-thickness tears of the supraspinatus tendon, about one third bicipital tendonitis, 18% irregularities of the humeral greater tuberosity, 10% subdeltoid bursitis and about 10% calcified tendonitis. In about a quarter of the patients, no pathology was found. Many patients had more than one lesion.

In conclusion, clinicians encountering shoulder pain should not be content with conventional radiography and are encouraged to make sonographic examinations part of the early diagnostic protocol.
A PROJECT MODEL IN MANAGING PRODUCTION RAMP-UP — A CASE STUDY IN WIRE HARNESS INDUSTRY
Authors: KONTIO JYRI , HAAPASALO HARRI
Published: April 2005

As a result of fierce competition, companies are striving for internal efficiency in all their functions and operations. Different theoretical perspectives for management exist, and there are always new expectations and requirements such as in the management of production ramp-up. The purpose of this paper is to present a project model to enhance process planning and production ramp-up in project management. The case project is in the wire harness industry. The paper illustrates practices for project management based on relevant literature.
SOFTWARE ARCHITECTURE FOR A MULTI-SITE PRODUCTION PLANNING AND CONTROL
Authors: HEAH WHEY SEEN , OMAR MOHAMED KHALED
Published: April 2005

In order to gain competitive advantage in the globalization today, effective management strategies need to be incorporated, especially in collaborating information sharing among multi-site manufacturing facilities. Information visibility within the supply chain is the process of sharing critical data required to manage the flow of products, services, and information in real time between suppliers and customers. If the information is available but cannot be accessed by the parties most able to react to a given situation, its value degrades drastically. We propose a software system, which incorporates mathematical models, user-interface and web application to solve the collaborative planning problems between multiple sites. Model validations proved the architecture to be robust and suggested cost savings through priority goal structuring. This paper offers a practical solution to real-life industrial problems often faced by the management of manufacturing industry in the world today.