Tests on light gage steel diaphragms

This report supplements and extends the scope of Report No. 319, ;lStructural Performance of Light Gage Steel Diaphragms , by Dr. Larry D. Luttrell. Eleven static load tests were conducted on 22 gage narrow rib roof decks to investigate the effect of length of the diaphragm, type of welding, and diaphragm material tensile properties on the shear stiffness and strength of the diaphragm. The behavior of a diaphragm under reversed load at two different levels) one at 0.4 x ultimate static load and the other at 0.6 x ultimate static load was explored by conducting five tests. The tests at a high level of reversed load (0.6 x Pu) were motivated by the fact that during earthquakes and blasts structures are subjected to high levels of reversed load for a few cycles. Three static load tests were performed on standard corrugated diaphragms to supplement the tests done by Dr. Luttrell and reported in Report No. 319 so as to formulate the strength (Plf.) of a diaphragm without intermediate fasteners* as a function of its thickness. It is confirmed by the above investigations that the shear stiffness of a diaphragm is dependent mainly on the length of the diaphragm, and the type and spacing of fasteners. The strength of a diaphragm is seen to be dependent mainly on the thickness of the diaphragm, and the type and spacing of the • The definition is the same as in Report 319. fasteners. Five cycles of reversed load at +0.6 x ultimate load of an identical diaphragm under static load resulted in a maximum reduction of 25% in strength of the diaphragm

Neuropilin-1 Controls Endothelial Homeostasis by Regulating Mitochondrial Function and Iron-Dependent Oxidative Stress.

The transmembrane protein neuropilin-1 (NRP1) promotes vascular endothelial growth factor (VEGF) and extracellular matrix signaling in endothelial cells (ECs). Although it is established that NRP1 is essential for angiogenesis, little is known about its role in EC homeostasis. Here, we report that NRP1 promotes mitochondrial function in ECs by preventing iron accumulation and iron-induced oxidative stress through a VEGF-independent mechanism in non-angiogenic ECs. Furthermore, NRP1-deficient ECs have reduced growth and show the hallmarks of cellular senescence. We show that a subcellular pool of NRP1 localizes in mitochondria and interacts with the mitochondrial transporter ATP-binding cassette B8 (ABCB8). NRP1 loss reduces ABCB8 levels, resulting in iron accumulation, iron-induced mitochondrial superoxide production, and iron-dependent EC senescence. Treatment of NRP1-deficient ECs with the mitochondria-targeted antioxidant compound mitoTEMPO or with the iron chelator deferoxamine restores mitochondrial activity, inhibits superoxide production, and protects from cellular senescence. This finding identifies an unexpected role of NRP1 in EC homeostasis

High power impulse magnetron sputtering discharges: Instabilities and plasma self-organization

We report on instabilities in high power impulse magnetron sputtering plasmas which are likely to be of the generalized drift wave type. They are characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron and cause periodic shifts in floating potential. The azimuthal mode number m depends on plasma current, plasma density, and gas pressure. The structures rotate in × direction at velocities of ∼10 km s−1 and frequencies up to 200 kHz. Collisions with residual gas atoms slow down the rotating wave, whereas increasing ionization degree of the gas and plasma conductivity speeds it up

Design recommendations for diaphragm-braced beams, columns and wall-studs

INTRODUCTION Light gage steel panels are often used as wall sheathing, roof decking or floor covering in steel framed buildings. These panels carry loads normal to their plane by virtue of their bending strength. Also, diaphragms formed by interconnecting such panels can resist shear deformation in their plane. Because of this shear resisting capacity, diaphragms can be very effective in bracing columns and beams of a steel frame against lateral buckling and, thus, increase the load carrying capacity of these members. For wall columns, such diaphragm bracing may be either directly attached or connected to girts which in turn are connected to the columns. The ribs of the panels must be perpendicular to the members to which they are attached. These diaphragms as wall, roof or floor, must be present in any event, and therefore, are available at no extra cost. If properly utilized for bracing, they can lead to economical design of beams and columns. Research has been conducted at Cornell University since 1961* (1),(2),(3) to determine the increased load carrying capacities of beams and columns due to diaphragm or diaphragmgirt bracing. Based on the results of the investigation to date, recommendations are made in this report for the design of beams and columns considering the effect of diaphragm braci~g. * Superscripts in parentheses refer to the numbers in the References. Design criteria are given in Part 2; the general design procedure in Part 3, and the specific design formulae in Part 4 are illustrated by some practical examples in Part 5. The design procedure suggested herein is based on the ultimate load capacity of the beams or columns, utilizing a conservative estimate of the strength and rigidity of the diaphragm bracing. Effectiveness of diaphragm bracing or diaphragm-girt bracing in preventing lateral buckling of beams and columns depends on its two fundamental characteristics: (1) rigidity, and (2) strength. In general, it is not economical to provide anything less than fUll bracing, where full bracing is defined as bracing such that any increase in rigidity or strength of diaphragm will not cause any substantial increase in the load carrying capacity of the braced members. Therefore, the design procedure in this report is limited to only fullyli braced beams and columns. The procedure is based on analyses of I-section beams under uniform moment, and I-section columns under axial load. These analyses have been substantiated by tests of thirtyfive diaphragm-braced assemblies as reported in the references. Information regarding the load carrying capacities of beams and columns with less than full bracing can be obtained from Reference 3. The capacity of channel and Z-section beams SUbjected to uniform moment also is discussed in Reference 3. Cantilever beams and channel and Z-section beams subjected to loads in the plane of the web are currently under investigation. Light wall studs braced by wallboard on one or both faces are no different basically from columns braced by light steel diaphragms. In order to make the methods developed here applicable to such wall studs, the Appendix gives a few typical test values for diaphragm rigidity and strength of customary types of wallboard

A New High Energy Photon Tagger for the H1 - Detector at HERA

The H1 detector at HERA has been upgraded by the addition of a new electromagnetic calorimeter. This is installed in the HERA tunnel close to the electron beam line at a position 8m from the interaction point in the electron beam direction. The new calorimeter extends the acceptance for tagged photoproduction events to the high y range, 0.85 < y < 0.95, and thus significantly improves the capability of H1 to study high energy gamma-p processes. The calorimeter design, performance and first results obtained during the 1996-1999 HERA running are described.Comment: 17 pages, 16 figure

Tagging High Energy Photons in the H1 Detector at HERA

Measures taken to extend the acceptance of the H1 detector at HERA for photoproduction events are described. These will enable the measurement of electrons scattered in events in the high y range 0.85 < y < 0.95 in the 1998 and 1999 HERA run period. The improvement is achieved by the installation of an electromagnetic calorimeter, the ET8, in the HERA tunnel close to the electron beam line 8 m downstream of the H1 interaction point in the electron direction. The ET8 will allow the study of tagged gamma p interactions at centre-of-mass energies significantly higher than those previously attainable. The calorimeter design and expected performance are discussed, as are results obtained using a prototype placed as close as possible to the position of the ET8 during the 1996 and 1997 HERA running.Comment: 13 pages, 13 figure

QCD Coherence and the Top Quark Asymmetry

Coherent QCD radiation in the hadroproduction of top quark pairs leads to a forward--backward asymmetry that grows more negative with increasing transverse momentum of the pair. This feature is present in Monte Carlo event generators with coherent parton showering, even though the production process is treated at leading order and has no intrinsic asymmetry before showering. In addition, depending on the treatment of recoils, showering can produce a positive contribution to the inclusive asymmetry. We explain the origin of these features, compare them in fixed-order calculations and the Herwig++, Pythia and Sherpa event generators, and discuss their implications.Comment: 28 pages, 11 figures, 2 table

The effects of matter density uncertainties on neutrino oscillations in the Earth

We compare three different methods to evaluate uncertainties in the Earth's matter density profile, which are relevant to long baseline experiments, such as neutrino factories.Comment: 3 pages, 1 figure. Talk given at the NuFact'02 Workshop, London, 1-6 July, 200