The Lincoln Story in Stone

This postcard features the Lincoln Story In Stone located at Lincoln Birthplace National Memorial in Indiana.https://scholarsjunction.msstate.edu/fvw-artifacts/5889/thumbnail.jp

The Lincoln Story in Stone

This postcard features the Lincoln Story In Stone located at Lincoln Birthplace National Memorial in Indiana.https://scholarsjunction.msstate.edu/fvw-artifacts/5890/thumbnail.jp

Multiple sediment incorporation events in a continental magmatic arc: Insight from the metasedimentary rocks of the northern North Cascades, Washington (USA)

The rheology and composition of arc crust and the overall evolution of continental magmatic arcs can be affected by sediment incorporation events. The exhumed Cretaceous–Eocene North Cascades arc exposes abundant meta­ sedimentary rocks that were incorporated into the arc during multiple events. This study uses field relationships, detrital zircon geochronology, bulk rock geo­ chemistry, geothermometry, and quartz­in­garnet geobarometry to distinguish approximate contacts and emplacement depths for different metasedimentary units to better understand their protolith incorporation history and impact on the arc. The Skagit Gneiss Complex is one of the main deep crustal units of the North Cascades arc. It includes metasedimentary rocks with distinct detrital zircon signatures: Proterozoic–Cretaceous (Group 1) or Triassic–Cretaceous (Group 2) zircon populations. Both metasedimentary groups achieved near­ peak metamorphic conditions of 640–800 °C and 5.5–7.9 kbar; several Group 2 samples reveal the higher pressures. A third group of metasedimentary rocks, which was previously interpreted as metamorphosed equivalents of backarc sediments (Group 3), exhibited unimodal Triassic or bimodal Late Jurassic– Early Cretaceous detrital zircon signatures and achieved near­peak conditions of 570–700 °C and 8.7–10.5 kbar. The combined field and analytical data indi­ cate that protoliths of Group 1 and Group 2 metasedimentary rocks were successively deposited in a forearc basin and underthrusted into the arc as a relatively coherent body. Group 3 backarc sediments were incorporated into the arc along a transpressional step­over zone. The incorporation of both forearc and backarc sediments was likely facilitated by arc magmatism that weakened arc crust in combination with regional transpression

Phase II study of CC-486 (oral azacitidine) in previously treated patients with locally advanced or metastatic nasopharyngeal carcinoma

BACKGROUND: Treatment options are limited for recurrent nasopharyngeal carcinoma (NPC). We report results from a phase II study of CC-486 (oral azacitidine) in advanced NPC. PATIENTS AND METHODS: Patients with locally advanced or metastatic NPC and 1-2 prior treatment regimens received CC-486 300 mg daily on days 1-14 of 21-day cycles until disease progression or unacceptable toxicity. The first 6 patients of Asian-Pacific Islander (API) ethnicity received a reduced dose of 200 mg to preserve safety and tolerability; if well tolerated, subsequent API patients received CC-486 300 mg. The study could advance to stage 2 if > 4 patients achieved a response. Co-primary end-points were overall response rate (ORR) and progression-free survival (independent review). Key secondary end-points were overall survival and safety. RESULTS: Owing to faster-than-anticipated enrolment, 36 patients, including 13 of API ethnicity, were enrolled; the median age was 54.0 years. Most patients were male (81%) and had an Eastern Cooperative Oncology Group performance status 64 1 (97%). Among 25 efficacy-evaluable patients, the ORR was 12%; the median progression-free and overall survival were 4.7 and 18.0 months, respectively. The most common grade III/IV treatment-emergent adverse events were neutropenia (33%) and febrile neutropenia (11%). Twenty-one posttreatment deaths, primarily due to progressive disease or disease complications, and 1 on-treatment death (epistaxis, unrelated to study drug) occurred. The study did not advance to stage 2. CONCLUSION: CC-486 did not show sufficient clinical activity to support further development as monotherapy in this patient population. The safety profile of CC-486 in NPC was consistent with that in other solid tumours

ALS/FTD‐associated FUS activates GSK‐3β to disrupt the VAPB–PTPIP51 interaction and ER–mitochondria associations

Defective FUS metabolism is strongly associated with amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), but the mechanisms linking FUS to disease are not properly understood. However, many of the functions disrupted in ALS/FTD are regulated by signalling between the endoplasmic reticulum (ER) and mitochondria. This signalling is facilitated by close physical associations between the two organelles that are mediated by binding of the integral ER protein VAPB to the outer mitochondrial membrane protein PTPIP51, which act as molecular scaffolds to tether the two organelles. Here, we show that FUS disrupts the VAPB–PTPIP51 interaction and ER–mitochondria associations. These disruptions are accompanied by perturbation of Ca2+ uptake by mitochondria following its release from ER stores, which is a physiological read‐out of ER–mitochondria contacts. We also demonstrate that mitochondrial ATP production is impaired in FUS‐expressing cells; mitochondrial ATP production is linked to Ca2+ levels. Finally, we demonstrate that the FUS‐induced reductions to ER–mitochondria associations and are linked to activation of glycogen synthase kinase‐3β (GSK‐3β), a kinase already strongly associated with ALS/FTD

Quasi-periodic X-ray brightness fluctuations in an accreting millisecond pulsar

The relativistic plasma flows onto neutron stars that are accreting material from stellar companions can be used to probe strong-field gravity as well as the physical conditions in the supranuclear-density interiors of neutron stars. Plasma inhomogeneities orbiting a few kilometres above the stars are observable as X-ray brightness fluctuations on the millisecond dynamical timescale of the flows. Two frequencies in the kilohertz range dominate these fluctuations: the twin kilohertz quasi-periodic oscillations (kHz QPOs). Competing models for the origins of these oscillations (based on orbital motions) all predict that they should be related to the stellar spin frequency, but tests have been difficult because the spins were not unambiguously known. Here we report the detection of kHz QPOs from a pulsar whose spin frequency is known. Our measurements establish a clear link between kHz QPOs and stellar spin, but one not predicted by any current model. A new approach to understanding kHz QPOs is now required. We suggest that a resonance between the spin and general relativistic orbital and epicyclic frequencies could provide the observed relation between QPOs and spin.Comment: Published in the 2003 July 3 issue of Natur

Plasmon-pole approximation for semiconductor quantum wire electrons

We develop the plasmon-pole approximation for an interacting electron gas confined in a semiconductor quantum wire. We argue that the plasmon-pole approximation becomes a more accurate approach in quantum wire systems than in higher dimensional systems because of severe phase-space restrictions on particle-hole excitations in one dimension. As examples, we use the plasmon-pole approximation to calculate the electron self-energy due to the Coulomb interaction and the hot-electron energy relaxation rate due to LO-phonon emission in GaAs quantum wires. We find that the plasmon-pole approximation works extremely well as compared with more complete many-body calculations.Comment: 16 pages, RevTex, figures included. Also available at http://www-cmg.physics.umd.edu/~lzheng

Expansion of Vortex Cores by Strong Electronic Correlation in La2−x_{2-x}Srx_xCuO4_4 at Low Magnetic Induction

The vortex core radius \rv, defined as the peak position of the supercurrent around the vortex, has been determined by muon spin rotation measurements in the mixed state of \lscox for $x=0.13$, 0.15, and 0.19. At lower doping (x=0.13 and 0.15), \rv(T) increases with decreasing temperature T, which is opposite to the behavior predicted by the conventional theory. Moreover, \rv(T\to0) is significantly larger than the Ginsburg-Landau coherence length determined by the upper critical field, and shows a clear tendency to decrease with increasing the doping x. These features can be qualitatively reproduced in a microscopic model involving antiferromagnetic electronic correlations.Comment: 6 pages, 4 figures, to be published in Phys. Rev.

Inelastic lifetimes of confined two-component electron systems in semiconductor quantum wire and quantum well structures

We calculate Coulomb scattering lifetimes of electrons in two-subband quantum wires and in double-layer quantum wells by obtaining the quasiparticle self-energy within the framework of the random-phase approximation for the dynamical dielectric function. We show that, in contrast to a single-subband quantum wire, the scattering rate in a two-subband quantum wire contains contributions from both particle-hole excitations and plasmon excitations. For double-layer quantum well structures, we examine individual contributions to the scattering rate from quasiparticle as well as acoustic and optical plasmon excitations at different electron densities and layer separations. We find that the acoustic plasmon contribution in the two-component electron system does not introduce any qualitatively new correction to the low energy inelastic lifetime, and, in particular, does not produce the linear energy dependence of carrier scattering rate as observed in the normal state of high-$T_c$ superconductors.Comment: 16 pages, RevTeX, 7 figures. Also available at http://www-cmg.physics.umd.edu/~lzheng

Superconductors with Magnetic Impurities: Instantons and Sub-gap States

When subject to a weak magnetic impurity potential, the order parameter and quasi-particle energy gap of a bulk singlet superconductor are suppressed. According to the conventional mean-field theory of Abrikosov and Gor'kov, the integrity of the energy gap is maintained up to a critical concentration of magnetic impurities. In this paper, a field theoretic approach is developed to critically analyze the validity of the mean field theory. Using the supersymmetry technique we find a spatially homogeneous saddle-point that reproduces the Abrikosov-Gor'kov theory, and identify instanton contributions to the density of states that render the quasi-particle energy gap soft at any non-zero magnetic impurity concentration. The sub-gap states are associated with supersymmetry broken field configurations of the action. An analysis of fluctuations around these configurations shows how the underlying supersymmetry of the action is restored by zero modes. An estimate of the density of states is given for all dimensionalities. To illustrate the universality of the present scheme we apply the same method to study `gap fluctuations' in a normal quantum dot coupled to a superconducting terminal. Using the same instanton approach, we recover the universal result recently proposed by Vavilov et al. Finally, we emphasize the universality of the present scheme for the description of gap fluctuations in d-dimensional superconducting/normal structures.Comment: 18 pages, 9 eps figure