bluuebunny/crossref_metadata_2025_split huggingface dataset:
QUANTUM SPIN CURRENT INDUCED THROUGH OPTICAL DIPOLE TRANSITION PROCESS IN SEMICONDUCTORS
Authors: LIU XIONG-JUN , KWEK L. C. , Oh C. H. 
Published: January 2008

We propose a scheme to generate quantum spin current via linear optical process. By interacting a three-level system based on the spin states of charged particles (electrons or holes in semiconductor, etc) with the angular momentum states of an optical field, we show that the dynamics of charged particles equipped with different spin polarizations are governed by different (opposite) additional effective magnetic fields. In this way, a pure dissipationless quantum spin current can be generated. No spin-orbit interaction (e.g., Rashba or Dresselhaus term) is needed in this scheme. We also calculate the effect of nonmagnetic impurities on the created spin currents and show that the vertex correction of the spin hall conductivity in the ladder approximation is exactly zero. Paper presented at NTU Spintronics Workshop, Singapore, May 2006.
SPIN RELATED TRANSPORT IN RASHBA 2DEG SYSTEMS
Authors: NITTA JUNSAKU 
Published: January 2008

Transport in mesoscopic conductors is determined not only by orbital motion of carriers but also by quantum interference effect. However, it is well known that the quantum interference such as weak localization is much modified in the presence of spin-orbit interaction (SOI), leading to weak anti-localization. We discuss the origin of the Rashba SOI and spin related mesoscopic transport in InGaAs based two dimensional electron gases (2DEG) affected by the Rashba SOI. It is experimentally shown that the strength of the Rashba SOI in InGaAs 2DEG systems can be controlled by the gate voltage.1 The spin dynamics in solid systems is commonly determined by the competition between Zeeman effect and SOI. The spin relaxation time and dephasing time are studied from weak anti-localization analysis as a function of the relative strength of the Zeeman energy (EZ) and the Rashba SOI energy (E SOI ). The (EZ) was introduced by applying magnetic field parallel to the 2DEG plane. This in-pane magnetic field does not affect the orbital motion of electrons. The spin relaxation time increases with the Zeeman energy. The dephasing time associated with the spin-induced time reversal symmetry (TRS) breaking saturates when EZ becomes comparable to E SOI . Moreover, we show that the spin-induced TRS breaking mechanism is a universal function of the ratio EZ/E SOI within the experimental accuracy.2 Note from Publisher: This article contains the abstract only.
CONTROLLING SPIN COHERENCE WITH SEMICONDUCTOR NANOSTRUCTURES
Authors: AWSCHALOM DAVID D. 
Published: January 2008

We present two emerging opportunities for manipulating and communicating coherent spin states in semiconductors. First, we show that semiconductor microcavities offer unique means of controlling light-matter interactions in confined geometries, resulting in a wide range of applications in optical communications and inspiring proposals for quantum information processing and computational schemes. Studies of spin dynamics in microcavities — a new and promising research field — have revealed novel effects such as polarization beats, stimulated spin scattering, and giant Faraday rotation. Here, we study the electron spin dynamics in optically-pumped GaAs microdisk lasers with quantum wells and interface-fluctuation quantum dots in the active region. In particular, we examine how the electron spin dynamics are modified by the stimulated emission in the disks, and observe an enhancement of the spin coherence time when the optical excitation is in resonance with a high quality ( Q ~ 5000) lasing mode.1 This resonant enhancement, contrary to expectations from the observed trend in the carrier recombination time, is then manipulated by altering the cavity design and dimensions. In analogy to devices based on excitonic coherence, this ability to engineer coherent interactions between electron spins and photons may provide novel pathways towards spin dependent quantum optoelectronics. In a second example, the nitrogen-vacancy (N-V) center in diamond has garnered interest as a room-temperature solid-state system not only for exploring electronic and nuclear spin phenomena but also as a candidate for spin-based quantum information processing. Spin coherence times of up to 50 microseconds have been reported for ensembles of N-V centers and a two-qubit gate utilizing the electron spin of a N-V center and the nuclear spin of a nearby C-13 atom has been demonstrated. Here, we present experiments using angle-resolved magneto-photoluminescence microscopy to investigate anisotropic spin interactions of single N-V centers in diamond at room temperature.2 Negative peaks in the photoluminescence intensity are observed as a function of both magnetic field magnitude and angle, and can be explained by coherent spin precession and anisotropic relaxation at spin-level anticrossings. Additionally, precise field alignment with the symmetry axis of a single N-V center reveals the resonant magnetic dipolar coupling of a single "bright" electron spin of an N-V center to small numbers of "dark" spins of nitrogen defects in its immediate vicinity, which are otherwise undetected by photoluminescence. Most recently, we are exploring the possibility of utilizing this magnetic dipole coupling between bright and dark spins to couple two spatially separated single N-V center spins by means of intermediate nitrogen spins. Note from Publisher: This article contains the abstract only.
MAGNETO-GYROTROPIC PHOTOGALVANIC EFFECTS IN SEMICONDUCTOR QUANTUM WELLS
Authors: GANICHEV S. D. 
Published: January 2008

The spin-orbit coupling provides a versatile tool to generate and to manipulate the spin degree of freedom in low-dimensional semiconductor structures. The spin Hall effect, where an electric current drives a transverse spin current and causes a nonequilibrium spin accumulation near the sample boundary,1,2 the spin-galvanic effect, where a nonequilibrium spin polarization drives an electric current3,4 or the reverse process, in which an electrical current generates a non-equilibrium spin-polarization,5–9 are all consequences of spin-orbit coupling. In order to observe a spin Hall effect a bias driven current is an essential prerequisite. Then spin separation is caused via spin-orbit coupling either by Mott scattering (extrinsic spin Hall effect) or by spin splitting of the band structure (intrinsic spin Hall effect). Recently an elementary effect causing spin separation which is fundamentally different from that of the spin Hall effect has been observed.10 In contrast to the spin Hall effect it does not require an electric current to flow: it is spin separation achieved by spin-dependent scattering of electrons in media with suitable symmetry. It is show that by free carrier (Drude) absorption of terahertz radiation spin separation is achieved in a wide range of temperatures from liquid helium temperature up to room temperature. Moreover the experimental results demonstrate that simple electron gas heating by any means is already sufficient to yield spin separation due to spin-dependent energy relaxation processes of non-equilibrium carriers. In order to demonstrate the existence of the spin separation due to asymmetric scattering the pure spin current was converted into an electric current. It is achieved by application of a magnetic field which polarizes spins. This is analogues to spin-dependent scattering in transport experiments: spin-dependent scattering in an unpolarized electron gas causes the extrinsic spin Hall effect, whereas in a spin-polarized electron gas a charge current, the anomalous Hall effect, can be observed. As both magnetic fields and gyrotropic mechanisms were used authors introduced the notation "magneto-gyrotropic photogalvanic effects" for this class of phenomena. The effect is observed in GaAs and InAs low dimensional structures at free-carrier absorption of terahertz radiation in a wide range of temperatures from liquid helium temperature up to room temperature. The results are well described by the phenomenological description based on the symmetry. Experimental and theoretical analysis evidences unumbiguously that the observed photocurrents are spin-dependent. Microscopic theory of this effect based on asymmetry of photoexcitation and relaxation processes are developed being in a good agreement with experimental data. Note from Publisher: This article contains the abstract only.
LESSONS FROM INTRODUCING NEW SCIENTIFIC DISCIPLINES INTO EUROPEAN SPACE RESEARCH
Authors: HUBER MARTIN C. E. 
Published: January 2008

Physics experiments in space will permit us to investigate natural phenomena that cannot be observed on the ground, such as low-frequency gravitational waves, and to reach uncharted realms of accuracy — accessible only through experiments carried out in space — where current foundations of physics can be further tested and potentially falsified. Such projects require technologies that have not been in hand for a long time but are available now. To avoid conflict of interest, the merit of space projects in physics, from the proposal stage through development, ought to be judged by experts in physics, rather than by space scientists from other fields. It is time now to set aside some funding to let missions in fundamental physics compete fairly with the established space sciences, thereby enriching and deepening the space enterprise — and broadening its advocacy base. We look, in the context of the European space scene, at the measures and events that resurrected the initially suppressed planetary sciences and brought solar physics to blooming after a long drought; and derive ideas on how to increase the number of flight opportunities for fundamental physics in space.
The Neoproterozoic Quatipuru ophiolite and the Araguaia fold belt, central-northern Brazil, compared with correlatives in NW Africa
Authors: Paixão M. A. P. , Nilson A. A. , Dantas E. L. 
Published: January 2008

Abstract
The Araguaia Belt, the northern branch of Neoproterozoic Tocantins tectonic province, developed during West Gondwana amalgamation as a result of collision between the Amazon and West African and/or São Francisco/Congo cratons. The external zone of the belt consists of ophiolitic slices and fragments, sedimentary rocks derived from magmatic arc sources, volcanic rocks, and part of a passive continental margin with low-grade metamorphic rocks, while the internal zone corresponds to a pile of low- to medium-grade metasedimentary rocks. The largest and best preserved ophiolitic bodies occur in the southern part of the belt, where the Quatipuru and Morro do Agostinho ophiolites are composed predominantly of mantle peridotites (mainly residual harzburgite) representing the base of the Moho transition zone. They contain chromitite pods, dunitic lensoid bodies and a suite of mafic–ultramafic dykes and/or sills resulting from partial melting, magma impregnation and diapiric up-rise. A Sm–Nd isochron age of 757±49 Ma indicates oceanic crust formation during the Early Neoproterozoic. NW African correlatives of the Araguaia Belt, the Mauritanide–Bassaride–Rokelide belt, show similarities with respect to lithostratigraphic units, the ages of basement and supracrustal rocks, the presence of Neoproterozoic ophiolitic slices and fragments, suture zones characterized by high gravity anomalies and centrifugal tectonic vergence. We conclude that these belts were probably formed around the same Neoproterozoic ocean or several small coeval oceans.
Late Neoproterozoic and Early Cambrian palaeogeography: models and problems
Authors: Pisarevsky S. A. , Murphy J. B. , Cawood P. A. , Collins A. S. 
Published: January 2008

Abstract
We present two alternative sets of global palaeogeographical reconstructions for the time interval 615–530 Ma using competing high and low-latitude palaeomagnetic data subsets for Laurentia in conjunction with geological data. Both models demonstrate a genetic relationship between the collisional events associated with the assembly of Gondwana and the extensional events related to the opening of the Tornquist Sea, the eastern Iapetus Ocean (600–550 Ma), and the western Iapetus Ocean (after 550 Ma), forming a three-arm rift between Laurentia, Baltica, and Gondwana. The extensional events are probably plume-related, which is indicated in the reconstructions by voluminous mafic magmatism along the margins of palaeo-continents. The low-latitude model requires a single plume event, whereas the high-latitude model needs at least three discrete plumes. Coeval collisions of large continental masses during the assembly of Gondwana, as well as slab pull from subduction zones associated with those collisions, could have caused upper plate extension resulting in the rifted arm that developed into the eastern Iapetus Ocean and Tornquist Sea but retarded development of the western Iapetus Ocean. As a result, the eastern Iapetus Ocean and the Tornquist Sea opened before the western Iapetus Ocean.
Proterozoic evolution of the Nigeria–Boborema province
Authors: Dada S. S. 
Published: January 2008

Abstract

Structural, geochronological, geochemical and mineralization patterns in the Nigeria–Borborema province of western Africa and NE Brazil reflect a complex Proterozoic evolution culminating in the Neoproterozoic Pan-African/Brasiliano orogenesis (
c
. 600 Ma). Reworking of the Archaean–early Proterozoic crust produced heterogeneous deformation exemplified by prevalent shears, migmatization, granitization and intrusion of large volumes of granitoids typical of a Himalayan-type thickened crust resulting from continent–continent collision. Dominant north–south to east–west structures, with prominent penetrative fabric and mylonitised wrench faults, refolded, transpressed, or even obliterated older structural trends, which are preserved in nappes of the central Sahara region (NW Africa to Nigeria) and in NE Brazil. Anatexis and recrystallisation were coeval with emplacement of Pan-African granitoids throughout this mobile belt. Bulk chemical modification, especially affecting magmatophile elements and REE patterns, attest to chemical exchange between Archaean basement and Pan-African/Brasiliano rocks. Older crust is present in both regions, including early (3.6–3.5 Ga), mid (3.1 Ga) and late (2.7–2.5 Ga) Archaean, as well as large areas of Palaeoproterozoic rocks reworked by the
c
. 600 Ma tectono-thermal events. The extent and interpretation of Eburnian/Transamazonian (2.1–2.0 Ga) events have not yet been resolved due to inadequate structural and isotopic data. Litho-structural control of Au, Sn, Nb and Ta mineralization relates to main or late-stage Pan-African deformation.
Human Leukocyte Antigen–G and Cancer Immunoediting
Authors: Urosevic Mirjana , Dummer Reinhard 
Published: February 2008

Abstract
Immunosurveillance is an extrinsic mechanism of cancer suppression that eliminates nascent tumors. However, the selection imposed by immunosurveillance can drive tumor evolution and the emergence of clinically apparent neoplasms. Mechanisms of immune escape acquired by less immunogenic variants during this process, termed immunoediting, may contribute significantly to malignant progression. In this review, we summarize the evidence that up-regulation of the nonclassic human leukocyte antigen (HLA) class I molecule HLA-G in tumor cells plays an important role in cancer and immune escape. [Cancer Res 2008;68(3):627–30]
Systematic High-Content Proteomic Analysis Reveals Substantial Immunologic Changes in Colorectal Cancer
Authors: Berndt Uta , Philipsen Lars , Bartsch Sebastian , Wiedenmann Bertram , Baumgart Daniel C. , Hämmerle Marcus , Sturm Andreas 
Published: February 2008

AbstractThe immune system is a significant determinant of epithelial tumorigenesis, but its role in colorectal cancer pathogenesis is not well understood. The function of the immune system depends upon the integrity of the protein network environment, and thus, we performed MELC immunofluorescence microscopy focusing on the lamina propria. By analyzing structurally intact tissues from colorectal cancer, ulcerative colitis, and healthy colonic mucosa, we used this unique and novel highly multiplexed robotic-imaging technology, which allows visualizing dozens of proteins simultaneously, and explored the toponome in colorectal cancer mucosa for the first time. We identified 1,930 motifs that distinguish control from colorectal cancer tissue. In colorectal cancer, the number of activated T cells is increased, explained by a lack of bax, caspase-3, and caspase-8. Whereas CD4+CD25+ T cells are decreased and are, other than in ulcerative colitis, not activated, cytotoxic T cells are significantly increased in colorectal cancer. Furthermore, the number of activated human lymphocyte antigen (HLA)-DR+ T-cells is increased in colorectal cancer, pointing to an altered antigen presentation. In colorectal cancer, CD3+CD29+ expression and assembly of the LFA-1 and LFA-3 receptor are differentially changed, indicating a distinct regulation of T-cell adhesion in colorectal cancer. We also identified increased numbers of natural killer and CD44+ cells in the colorectal cancer mucosa and nuclear factor-κB as regulator of apoptosis in these cell populations. High-content proteomic analysis showed that colorectal cancer induces a tremendous modification of protein expression profiles in the lamina propria. Thus, topological proteomic analysis may help to unravel the role of the adaptive immune system in colorectal cancer and aid the development of new antitumor immunotherapy approaches. [Cancer Res 2008;68(3):880–8]
Thymidylate Synthase and Methylenetetrahydrofolate Reductase Gene Polymorphisms and Toxicity to Capecitabine in Advanced Colorectal Cancer Patients
Authors: Sharma Rohini , Hoskins Janelle M. , Rivory Laurent P. , Zucknick Manuela , London Rosyln , Liddle Christopher , Clarke Stephen J. 
Published: February 2008

Abstract
Purpose: To evaluate the effect of thymidylate synthase (TYMS) and methylenetetrahydrofolate reductase (MTHFR) genotypes on toxicity in patients treated with capecitabine for advanced colorectal cancer and to determine the effect of these polymorphisms on the pretreatment levels of serum folate and plasma homocysteine.
Experimental Design: Fifty-four patients with a diagnosis of metastatic colorectal cancer were treated with fixed-dose capecitabine. Germ line DNA from patients was genotyped for TYMS TSER, TSER*3G&gt;C, and 3′-untranslated 6 bp insertion/deletion (3′ untranslated region insertion/deletion), and MTHFR c.677C&gt;T and c.1298A&gt;C using PCRs and RFLP. Toxicity was graded by National Cancer Institute Common Toxicity Criteria version 2.0. Response was assessed by Response Evaluation Criteria in Solid Tumors.
Results: MTHFR c.677C&gt;T and c.1298A&gt;C genotypes and diplotypes predicted for grade 2/3 toxicities, whereas the TYMS genotypes had no influence. MTHFR c.677 genotype tended to predict overall survival (P = 0.08). MTHFR c.677 influenced pretreatment homocysteine (P &lt; 0.05) and serum folate levels (P &lt; 0.05). Multivariate analysis suggests that MTHFR c.1298 is an independent predictor of toxicity.
Conclusions: This study suggests that common genetic variation in MTHFR but not TYMS may be useful for predicting toxicity from capecitabine in patients with advanced colorectal cancer. In addition, MTHFR single nucleotide polymorphisms predicted serum folate and plasma homocysteine levels, and, combined, these factors may be important predictors of capecitabine-induced toxicity.
Reduction of Glucose Metabolic Activity Is More Accurate than Change in Size at Predicting Histopathologic Response to Neoadjuvant Therapy in High-Grade Soft-Tissue Sarcomas
Authors: Evilevitch Vladimir , Weber Wolfgang A. , Tap William D. , Allen-Auerbach Martin , Chow Kira , Nelson Scott D. , Eilber Fredrick R. , Eckardt Jeffery J. , Elashoff Robert M. , Phelps Michael E. , Czernin Johannes , Eilber Fritz C. 
Published: February 2008

Abstract
Purpose: Change in tumor size as classified by Response Evaluation Criteria in Solid Tumors poorly correlates with histopathologic response to neoadjuvant therapy in patients with soft-tissue sarcomas. The aim of this study was to prospectively evaluate whether positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) allows for a more accurate evaluation of histopathologic response.
Experimental Design: From January 2005 to January 2007, 42 patients with resectable biopsy-proven high-grade soft-tissue sarcoma underwent a FDG-PET/computed tomography scan before and after neoadjuvant treatment. Relative changes in tumor FDG uptake and size from the baseline to the follow-up scan were calculated, and their accuracy for assessment of histopathologic response was compared by receiver operating characteristic curve analysis. Histopathologic response was defined as ≥95% tumor necrosis.
Results: In histopathologic responders (n = 8; 19%), reduction in tumor FDG uptake was significantly greater than in nonresponders (P &lt; 0.001), whereas no significant differences were found for tumor size (P = 0.24). The area under the receiver operating characteristic curve for metabolic changes was 0.93, but only 0.60 for size changes (P = 0.004). Using a 60% decrease in tumor FDG uptake as a threshold resulted in a sensitivity of 100% and a specificity of 71% for assessment of histopathologic response, whereas Response Evaluation Criteria in Solid Tumors showed a sensitivity of 25% and a specificity of 100%.
Conclusion: Quantitative FDG-PET was significantly more accurate than size-based criteria at assessing histopathologic response to neoadjuvant therapy. FDG-PET should be considered as a modality to monitor treatment response in patients with high-grade soft-tissue sarcoma.
Molecular Targeting and Treatment of Composite EGFR and EGFRvIII-Positive Gliomas Using Boronated Monoclonal Antibodies
Authors: Yang Weilian , Wu Gong , Barth Rolf F. , Swindall Michele R. , Bandyopadhyaya Achintya K. , Tjarks Werner , Tordoff Kevin , Moeschberger Melvin , Sferra Thomas J. , Binns Peter J. , Riley Kent J. , Ciesielski Michael J. , Fenstermaker Robert A. , Wikstrand Carol J. 
Published: February 2008

AbstractPurpose: The purpose of the present study was to evaluate the anti–epidermal growth factor receptor (EGFR) monoclonal antibody (mAb), cetuximab, (IMC-C225) and the anti-EGFRvIII mAb, L8A4, used in combination as delivery agents for boron neutron capture therapy (BNCT) of a rat glioma composed of a mixture of cells expressing either wild-type (F98EGFR) or mutant receptors(F98npEGFRvIII).Experimental Design: A heavily boronated polyamidoamine dendrimer (BD) was linked by heterobifunctional reagents to produce the boronated mAbs, BD-C225 and BD-L8A4. For in vivo biodistribution and therapy studies, a mixture of tumor cells were implanted intracerebrally into Fischer rats. Biodistribution studies were carried out by administering 125I-labeled bioconjugates via convection-enhanced delivery (CED), and for therapy studies, nonradiolabeled bioconjugates were used for BNCT. This was carried out 14 days after tumor implantation and 24 h after CED at the Massachusetts Institute of Technology nuclear reactor.Results: Following CED of a mixture of 125I-BD-C225 and 125I-BD-L8A4 to rats bearing composite tumors, 61.4% of the injected dose per gram (ID/g) was localized in the tumor compared with 30.8% ID/g for 125I-BD-L8A4 and 34.7% ID/g for 125I-BD-C225 alone. The corresponding calculated tumor boron values were 24.4 μg/g for rats that received both mAbs, and 12.3 and 13.8 μg/g, respectively, for BD-L8A4 or BD-C225 alone. The mean survival time of animals bearing composite tumors, which received both mAbs, was 55 days (P &lt; 0.0001) compared with 36 days for BD-L8A4 and 38 days for BD-C225 alone, which were not significantly different from irradiated controls.Conclusions: Both EGFRvIII and wild-type EGFR tumor cell populations must be targeted using a combination of BD-cetuximab and BD-L8A4. Although in vitro C225 recognized both receptors, in vivo it was incapable of delivering the requisite amount of 10B for BNCT of EGFRvIII-expressing gliomas.