16,850 research outputs found
HIV-associated nephropathy - an initial presentation in an HIV-positive patient
The lesions of HIV-associated nephropathy occur in patients with AIDS, AIDS-related complex and in individuals clinically asymptomatic for HIV infection. We report on a 35-year-old black South African Woman who presented with nephrotic syndrome and renal failure. The renal biopsy appearance suggested mv infection and this was subsequently verified. This finding emphasises the possibility that otherwise asymptomatic patients presenting with renal disease may be HIV-positive
Fiber-Cavity-Based Optomechanical Device
We describe an optomechanical device consisting of a fiber-based optical
cavity containing a silicon nitiride membrane. In comparison with typical
free-space cavities, the fiber-cavity's small mode size (10 {\mu}m waist, 80
{\mu}m length) allows the use of smaller, lighter membranes and increases the
cavity-membrane linear coupling to 3 GHz/nm and quadratic coupling to 20
GHz/nm^2. This device is also intrinsically fiber-coupled and uses glass
ferrules for passive alignment. These improvements will greatly simplify the
use of optomechanical systems, particularly in cryogenic settings. At room
temperature, we expect these devices to be able to detect the shot noise of
radiation pressure.Comment: 4 pages, 3 figures; the following article has been submitted to
Applied Physics Letter
Heavy Quarkonium Potential Model and the State of Charmonium
A theoretical explanation of the observed splittings among the P~states of
charmonium is given with the use of a nonsingular potential model for heavy
quarkonia. We also show that the recently observed mass difference between the
center of gravity of the states and the state of
does not provide a direct test of the color hyperfine interaction in heavy
quarkonia. Our theoretical value for the mass of the state is in
agreement with the experimental result, and its E1 transition width is
341.8~keV. The mass of the state is predicted to be 3622.3~MeV.Comment: 15 page REVTEX documen
Observed acoustic and aeroelastic spectral responses of a MOD-2 turbine blade to turbulence excitation
Early results from a recent experiment designed to directly evaluate the aeroacoustic/elastic spectral responses of a MOD-2 turbine blade to turbulence-induced unsteady blade loads are discussed. The experimental procedure consisted of flying a hot-film anemometer from a tethered balloon in the turbine inflow and simultaneously measuring the fluctuating airload and aeroelastic response at two blade span stations (65% and 87% spans) using surface-mounted, subminiature pressure transducers and standard strain gage instrumentation. The radiated acoustic pressure field was measured with a triad of very-low-frequency microphones placed at ground level, 1.5 rotor diameters upwind of the disk. Initial transfer function estimates for acoustic radiation, blade normal forces, flapwise acceleration/displacement, and chord/flapwise moments are presented
Holocene Environmental Change in the Frobisher Bay Area, Baffin Island, N.W.T.: Deglaciation, Emergence, and the Sequence of Vegetation and Climate
The late-glacial and Holocene paleoenvironmental sequence for the Frobisher Bay area is outlined using glacial, sea level, and palynological evidence. A rapid retreat of ice from the late Foxe glacial maximum in the lower part of the bay after 11,000 BP was followed by a series of stillstands or minor readvances between ca. 8500 and 7000 BP and possibly later, before the final disappearance of the inland ice centred near Amadjuak Lake. Lithostratigraphy of three buried organic sections which together represent deposition occurring over the period from 5500 to 400 BP indicates a change from a relatively warm, moist environment before 5500 BP to neoglacial conditions, with the coldest phases centred around 5000, 2700, 1200 BP and probably sometime after 400 radiocarbon years BP. As evidenced by peat growth and pollen data, milder, wetter conditions prevailed from 4500 to 3000 BP and again from ca. 2600 to 1800 BP. Peat growth and soil organic fractions point to lesser mild intervals ca. 900 BP and 400 BP, but these are not apparent in the pollen assemblage. The pollen record does not extend to the last four centuries; however, lichenometric studies of neoglacial moraines by DOWDESWELL (1984) show that the maximum late Holocene advance of glaciers in the area occurred within the last century. Modern pollen samples indicate that the present vegetation of the inner Frobisher Bay area is comparable to that of the milder intervals of the late Holocene.La prĂ©sente Ă©tude porte sur l'Ă©volution palĂ©oenvironnementale fini-glaciaire et holocĂšne de la rĂ©gion de la baie de Frobisher et se fonde sur les niveaux marins ainsi que sur des tĂ©moins polliniques et glaciaires. Le retrait rapide des glaciers dans la partie intĂ©rieure de la baie depuis 11 000 BP a Ă©tĂ© suivi d'Ă©pisodes de stabilitĂ© et de rĂ©currences mineures entre 8500 et 7000 ans BP. et peut-ĂȘtre plus tard, avant la disparition dĂ©finitive des glaces continentales dont le centre se trouvait prĂšs du lac Amadjuak. L'analyse a portĂ© sur trois sections de sol enfoui qui reprĂ©sentent les dĂ©pĂŽts accumulĂ©s entre 5500 et 400 ans BP. La lithostratigraphie rĂ©vĂšle le passage d'un climat relativement humide et chaud, il y a plus de 5500 ans, Ă un climat nĂ©oglaciaire dont les pĂ©riodes les plus froides se situent vers 5000, 2700 et 1200 ans BP et probablement aprĂšs 400 ans BP. La tourbe et les donnĂ©es polliniques tĂ©moignent de conditions climatiques plus douces et plus humides pour les pĂ©riodes allant de 4500 Ă 3000 ans BP et d'environ 2600 Ă 1800 ans BP. Mais, contrairement aux associations polliniques, la tourbe et certaines portions organiques de sol font penser qu'ont existĂ© des intervalles plus frais environ de 900 Ă 400 ans BP. Les donnĂ©es pollinique ne donnent aucun renseignement sur les quatre derniers siĂšcles. Cependant, les Ă©tudes Ii-chĂ©nomĂ©triques que DOWDESWELL (1984) a faites sur les moraines nĂ©oglaciaires rĂ©vĂšlent que, dans la rĂ©gion pendant l'HolocĂšne supĂ©rieur, l'avancĂ©e maximale des glaces s'est produite au siĂšcle dernier. Des Ă©chantillons polliniques rĂ©cents dĂ©montrent que la vĂ©gĂ©tation actuelle de l'intĂ©rieur de la baie de Frobisher ressemble Ă celle qu'on trouvait pendant les intervalles tempĂ©rĂ©s de l'HolocĂšne supĂ©rieur.Die spĂ tglaziale und holozĂ ne Abfolge des PalĂąomilieus im Gebiete der Frobisher Bucht wird durch glaziale, Meeresspiegel- und palynologische Beweise umrissen. Ein rasches ZurĂčckweichen des Eises aus dem niederen Teil der Bucht hat sich nach 11 000 BP ereignet. gefolgt von mehreren StillstĂąnden oder kleinerem WiedervorrĂčcken zwischen etwa 8500 und 7000 BP oder evtl. spater, bevor das Inlandeis schliesslich verschwunden ist. Drei verdeckte Bodenprofile sind analysiert worden, die zu-sammen die Ablagerung der Zeit von 5500 bis 400 BP darstellen. Die Lithostratigraphie hat eine relativ warme, feuchte Umgebung vor 5500 BP ergeben, die sich alsdann zu neoglazialen ZustĂąnden geĂ ndert hat, mit dem Mittel der kĂąltesten Phasen um etwa 5000, 2700, und wahrscheinlich auch irgandwann nach 400 Radiokohlenstoffjahren BP. Torfwuchs sowie auch palynologische Daten zeigen, dass milde, feuchte ZustĂąnde von 4500 bis 3000 BP und dann nochmals von etwa 2600 bis 1800 BP vorgeherrscht haben. Der Torfwuchs und der organische Anteil des Bodens deuten auch auf kleinere milde Zeitspannen um etwa 900 und 400 BP, aber diĂšse sind nicht aus der Pollenvergesellschaftung ersichtlich. Fur die jĂčngsten vier Jahrhunderte fehlen Pollenunterlagen; aber durch Untersuchung der Flechten auf neoglazialen MorĂąnen hat DOWDESWELL (1984) fur dieses Gebiet ein spatholozĂ nes GletschervorrĂčcken wahrend des letzten Jahrhunderts belegen konnen. Pollenmuster beweisen. dass sich im Gebiet der inneren Frobisher Bucht die heutige Pflanzendecke gut mit der Vegetation mlldererer SpĂątholozĂ nintervalle vergleichen lĂ sst
Global wave loads on a damaged ship
A computational tool was applied based on a two dimensional linear method to predict the hydrodynamic loads for damaged ships. Experimental tests on a ship model have also been carried out to predict the hydrodynamic loads in various design conditions. The results of the theoretical method and experimental tests are compared to validate the theoretical method. The extreme wave induced loads have been calculated by short term prediction. For the loads in intact condition, the prediction with duration of 20 years at sea state 5 is used, while for loads in damaged conditions the prediction in 96 hours exposure time at sea 3 is used. The maximum values of the most probable extreme amplitudes of dynamic wave induced loads in damaged conditions are much less than those in intact condition because of the reduced time. An opening could change the distribution of not only stillwater bending moment but also wave-induced bending moment. It is observed that although some cross sections are not structurally damaged, the total loads acting on these cross sections after damage may be increased dramatically compared to the original design load in intact condition
Lower critical field H_c1 and barriers for vortex entry in Bi_2Sr_2CaCu_2O_{8+delta} crystals
The penetration field H_p of Bi_2Sr_2CaCu_2O_{8+delta} crystals is determined
from magnetization curves for different field sweep rates dH/dt and
temperatures. The obtained results are consistent with theoretical reports in
the literature about vortex creep over surface and geometrical barriers. The
frequently observed low-temperature upturn of H_p is shown to be related to
metastable configurations due to barriers for vortex entry. Data of the true
lower critical field H_c1 are presented. The low-temperature dependence of H_c1
is consistent with a superconducting state with nodes in the gap function.
[PACS numbers: 74.25.Bt, 74.60.Ec, 74.60.Ge, 74.72.Hs
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