Observation of blue-shifted ultralong-range Cs2_{2} Rydberg molecules

We observe ultralong-range blue-shifted Cs$_{2}$ molecular states near $ns_{1/2}$ Rydberg states in an optical dipole trap, where $31\leq n\leq34$. The accidental near degeneracy of $(n-4)l$ and $ns$ Rydberg states for $l>2$ in Cs, due to the small fractional $ns$ quantum defect, leads to non-adiabatic coupling among these states, producing potential wells above the $ns$ thresholds. Two important consequences of admixing high angular momentum states with $ns$ states are the formation of large permanent dipole moments, $\sim 15-100\,$Debye, and accessibility of these states via two-photon association. The observed states are in excellent agreement with theory. Both projections of the total angular momentum on the internuclear axis are visible in the experiment

Mechanisms Affecting Emission in Rare-Earth-Activated Phosphors

The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. The authors research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low-energy electron beams are used to excite the emission

Analysis of Carbon/Carbon Fragments From the Columbia Tragedy

The extensive investigation following the Space Shuttle Orbiter Columbia accident of February 1, 2003 determined that hot gases entered the wing through a breach in the protective reinforced carbon/carbon (RCC) leading edge. In the current study, the exposed edges of the recovered RCC from the vicinity of the breach are examined with scanning electron microscopy and Raman spectroscopy. Electron microscopy of the exposed edges revealed regions of pointed carbon fibers, characteristic of exposure to high temperature oxidizing gases. The Raman technique relates the observed 1350 and 1580 to 1600 cm(-1) bands to graphitic dom ains and their corresponding temperatures of formation. Some of the regions showed evidence of exposure temperatures beyond 2700 ?C during the accident

The New Role of Business in Global Education: How Companies Can Create Shared Value by Improving Education While Driving Shareholder Returns

This paper articulates the case for a renewed role for business in global education through the lens of shared value. It is intended to help business leaders and their partners seize opportunities to create economic value while addressing unmet needs in education at scale. The concepts we describe apply across industries and to developed and emerging economies alike, although their implementation will naturally differ based on contex

Immodest and proud

In his ‘Ambitious, Yet Modest, Metaphysics’, Hofweber (Metametaphysics, Oxford University Press, Oxford, pp 260–289, 2009a) puts forward arguments against positions in metaphysics that he describes as ‘immodest’; a position he identifies as defended by Jonathan Lowe. In this paper I reply to Hofweber’s arguments, offering a defence of immodest metaphysics of the type practiced by Lowe (The possibility of metaphysics, Oxford University Press, Oxford, 1998) inter alia

An inhibitor of HIV-1 protease modulates constitutive eIF2α dephosphorylation to trigger a specific integrated stress response.

Inhibitors of the HIV aspartyl protease [HIV protease inhibitors (HIV-PIs)] are the cornerstone of treatment for HIV. Beyond their well-defined antiretroviral activity, these drugs have additional effects that modulate cell viability and homeostasis. However, little is known about the virus-independent pathways engaged by these molecules. Here we show that the HIV-PI Nelfinavir decreases translation rates and promotes a transcriptional program characteristic of the integrated stress response (ISR). Mice treated with Nelfinavir display hallmarks of this stress response in the liver, including α subunit of translation initiation factor 2 (eIF2α) phosphorylation, activating transcription factor-4 (ATF4) induction, and increased expression of known downstream targets. Mechanistically, Nelfinavir-mediated ISR bypassed direct activation of the eIF2α stress kinases and instead relied on the inhibition of the constitutive eIF2α dephosphorylation and down-regulation of the phophatase cofactor CReP (Constitutive Repressor of eIF2α Phosphorylation; also known as PPP1R15B). These findings demonstrate that the modulation of eIF2α-specific phosphatase cofactor activity can be a rheostat of cellular homeostasis that initiates a functional ISR and suggest that the HIV-PIs could be repositioned as therapeutics in human diseases to modulate translation rates and stress responses

Surface charging of phosphors and its effects on cathodoluminescence at low electron energies

Measurements of the threshold for secondary electron emission and shifts of the carbon Auger line position have been used to deduce the surface potential of several common phosphors during irradiation by electrons in the 0.5--5.0 keV range. All of the insulating phosphors display similar behavior: the surface potential is within {+-}1 V of zero at low electron energies. However, above 2--3 kV it becomes increasingly negative, reaching hundreds of volts within 1 keV of the turn-on energy. The electron energy at which this charging begins decreases dramatically after Coulomb aging at 17 {micro}A/cm{sup 2} for 30--60 min. Measurements using coincident electron beams at low and high electron energies to control the surface potential were made to investigate the dependence of the cathodoluminescence (CL) process on charging. Initially, the CL from the two beams is identical to the sum of the separate beam responses, but after Coulomb aging large deviations from this additivity are observed. These results indicate that charging has important, detrimental effects on CL efficiency after prolonged e-beam irradiation. Measurements of the electron energy dependence of the CL efficiency before and after Coulomb aging will also be presented, and the implications of these data on the physics of the low-voltage CL process will be discussed

Impairment of both IRE1 expression and XBP1 activation is a hallmark of GCB DLBCL and contributes to tumor growth.

The endoplasmic reticulum kinase inositol-requiring enzyme 1 (IRE1) and its downstream target X-box-binding protein 1 (XBP1) drive B-cell differentiation toward plasma cells and have been shown to contribute to multiple myeloma development; yet, little is known of the role of this pathway in diffuse large B-cell lymphoma (DLBCL). Here, we show that in the germinal center B-cell-like (GCB) DLBCL subtype, IRE1 expression is reduced to a level that prevents XBP1 activation. Gene expression profiles indicated that, in GCB DLBCL cancer samples, expression of IRE1 messenger RNA was inversely correlated with the levels and activity of the epigenetic repressor, histone methyltransferase enhancer of zeste homolog 2 (EZH2). Correspondingly, in GCB-derived cell lines, the IRE1 promoter carried increased levels of the repressive epigenetic mark histone 3 lysine 27 trimethylation. Pharmacological inhibition of EZH2 erased those marks and restored IRE1 expression and function in vitro and in vivo. Moreover, reconstitution of the IRE1-signaling pathway, by expression of the XBP1-active form, compromised GCB DLBCL tumor growth in a mouse xenograft cancer model. These findings indicate that IRE1-XBP1 downregulation distinguishes GCB DLBCL from other DLBCL subtypes and contributes to tumor growth

Atomic structure and vibrational properties of icosahedral B4_4C boron carbide

The atomic structure of icosahedral B$_4$C boron carbide is determined by comparing existing infra-red absorption and Raman diffusion measurements with the predictions of accurate {\it ab initio} lattice-dynamical calculations performed for different structural models. This allows us to unambiguously determine the location of the carbon atom within the boron icosahedron, a task presently beyond X-ray and neutron diffraction ability. By examining the inter- and intra-icosahedral contributions to the stiffness we show that, contrary to recent conjectures, intra-icosahedral bonds are harder.Comment: 9 pages including 3 figures, accepted in Physical Review Letter