Short-range force detection using optically-cooled levitated microspheres

We propose an experiment using optically trapped and cooled dielectric microspheres for the detection of short-range forces. The center-of-mass motion of a microsphere trapped in vacuum can experience extremely low dissipation and quality factors of $10^{12}$, leading to yoctonewton force sensitivity. Trapping the sphere in an optical field enables positioning at less than 1 $\mu$m from a surface, a regime where exotic new forces may exist. We expect that the proposed system could advance the search for non-Newtonian gravity forces via an enhanced sensitivity of $10^5-10^7$ over current experiments at the 1 $\mu$m length scale. Moreover, our system may be useful for characterizing other short-range physics such as Casimir forces.Comment: 4 pages, 3 figures, minor changes, Figs. 1 and 2 replace

Designing Web-Based Instruction: A Research Review On Color, Typography, Layout, and Screen Density

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A GIANT ANEURYSM OF PROPER HEPATIC ARTERY IN A CRYOGLOBULINEMIC PATIENT ON HEMODIALYSIS: A CASE REPORT.

Introductrion. Hepatic artery aneurysms (HAAs) are unusual vascular lesions often associated with many different pathological conditions. Most of reported cases are described in association with connective tissue diseases, such as polyarteritis nodosa and systemic lupus erythematosus. Case report. We observed a 52-year-old man with hypertension and HCV-related cryoglobulinemia complicated by end stage renal disease on replacement therapy by hemodialysis. He was admitted to our hospital because of the worsening of blood pressure values (170/110 mmHg) associated to new onset abdominal pain. After an initial physical examination, that showed a periumbelical bruit associated to a pulsatile mass in right hypocondrium, an abdominal ultrasound was performed with evidence of aneurysms of both the right branch (diameter max 4,5 cm) and the left branch (diameter max 1.5 cm) of the hepatic artery. An abdominal CT study was also performed and it confirmed the diagnosis of right intrahepatic artery aneurysm with partially thrombosed area in its peripheral distal portion. Discussion. Many different factors can contribute to the aneurysm formation in this patient. Vasculitic involvement due to cryoglobulinemic disease, therapy with steroid drugs, inflammatory state associated to HCV-related hepatitis, chronic kidney disease and replacement therapy by hemodialysis may all be involved in the development of the aneurysmatic hepatic lesion

Diversification of spatiotemporal expression and copy number variation of the echinoid hbox12/pmar1/micro1 multigene family

Changes occurring during evolution in the cis-regulatory landscapes of individual members of multigene families might impart diversification in their spatiotemporal expression and function. The archetypal member of the echinoid hbox12/pmar1/micro1 family is hbox12-a, a homeobox-containing gene expressed exclusively by dorsal blastomeres, where it governs the dorsal/ventral gene regulatory network during embryogenesis of the sea urchin Paracentrotus lividus. Here we describe the inventory of the hbox12/pmar1/micro1 genes in P. lividus, highlighting that gene copy number variation occurs across individual sea urchins of the same species. We show that the various hbox12/pmar1/micro1 genes group into three subfamilies according to their spatiotemporal expression, which ranges from broad transcription throughout development to transient expression in either the animal hemisphere or micromeres of the early embryo. Interestingly, the promoter regions of those genes showing comparable expression patterns are highly similar, while differing from those of the other subfamilies. Strikingly, phylogenetic analysis suggests that the hbox12/pmar1/micro1 genes are species-specific, exhibiting extensive divergence in their noncoding, but not in their coding, sequences across three distinct sea urchin species. In spite of this, two micromere-specific genes of P. lividus possess a TCF/LEF-binding motif in a similar position, and their transcription relies on Wnt/ f-catenin signaling, similar to the pmar1 and micro1 genes, which in other sea urchin species are involved in micromere specification. Altogether, our findings suggest that the hbox12/pmar1/micro1 gene family evolved rather rapidly, generating paralogs whose cis-regulatory sequences diverged following multiple rounds of duplication from a common ancestor

Effects of voids and flaws on the mechanical properties and on intergranular damage and fracture for polycrystalline materials

It is widely recognized that the macroscopic material properties depend on the features of the microstructure. The understanding of the links between microscopic and macroscopic material properties, main topic of Micromechanics, is of relevant technological interest, as it may enable the deep understanding of the mechanisms governing materials degradation and failure. Polycrystalline materials are used in many engineering applications. Their microstructure is determined by distribution, size, morphology, anisotropy and orientation of the crystals. It worth noting that also the physical-chemical properties of the intergranular interfaces, as well as the presence of micro-imperfections within the microstructure, have to be taken into account, as they may have to a strong influence on onset and evolution of damage

David St. Aubin (1952-2002)

Imagine the scene, Dave, strong, youthful and sharp-eyed, poised to leap off the bow of a swift-turning zodiac, hurl himself into the frigid Arctic waters, and deftly place a hoop-net over the head of a thrashing beluga whale. Each evening we would sit quietly on the cliffs, sharing the satisfaction of a good day's work .... The spectacle of the hundreds of belugas just below the bluff, rubbing in the shallows of Cunningham Inlet, made this one of Dave's favourite places. He was, after all, the one who had found out why belugas were there. ... Dave was the first to document that a whale could actually moult, in a peculiar kind of mammalian way. Dave started his research career as an assistant at the Arctic Biological Station, Fisheries and Oceans Canada, in Ste. Anne de Bellevue, Québec, .... Dave was clear in his vision and goals. In 1973, he decided on graduate training. Riding a wave of powerful recommendations, he arrived at the University of Guelph .... Dave earned his Master's degree and Ph.D., both with honours. ... From the moment Dave arrived at the university until the day he left 21 years later, ... three of us worked together from the Arctic to the tropics, from Maritime Canada to Florida, from Holman Island to South America to Hawaii- observing, studying, documenting, learning. ... In 1993, Dave went to Mystic Marine Life Aquarium as Director of Research and Veterinary Services. While south of the Canadian border, his interests and involvement in Arctic research grew stronger than ever. ... By today's measure, 50 years is a disappointingly short life, but Dave never wasted a moment and accomplished much. ..

Vitamin C in the Diet of Inuit Hunters From Holman, N.W.T.

During the spring and summer months the diet of three Inuit families living in a seal hunting camp south of Holman, N.W.T., was studied. A total of 13 food items including the most commonly eaten mammal, bird and plant species were analysed for Vitamin C in both the raw and cooked state. We document a daily intake of ascorbic acid of between 11 and 118 mg and estimate a mean dose of at least 30 mg. This is well above the levels documented in larger transitional culture villages by a recent Nutrition Canada report