Noise characterization of an atomic magnetometer at sub-millihertz frequencies

Noise measurements have been carried out in the LISA bandwidth (0.1 mHz to 100 mHz) to characterize an all-optical atomic magnetometer based on nonlinear magneto-optical rotation. This was done in order to assess if the technology can be used for space missions with demanding low-frequency requirements like the LISA concept. Magnetometry for low-frequency applications is usually limited by $1/f$ noise and thermal drifts, which become the dominant contributions at sub-millihertz frequencies. Magnetic field measurements with atomic magnetometers are not immune to low-frequency fluctuations and significant excess noise may arise due to external elements, such as temperature fluctuations or intrinsic noise in the electronics. In addition, low-frequency drifts in the applied magnetic field have been identified in order to distinguish their noise contribution from that of the sensor. We have found the technology suitable for LISA in terms of sensitivity, although further work must be done to characterize the low-frequency noise in a miniaturized setup suitable for space missions.Comment: 11 pages, 12 figure

The Salem Limestone in the Indiana Building-Stone District

Indiana Geological Survey Occasional Paper 38The limestone building material that has dominated the national market for more than a century is produced in the Bloomington-Bedford district of southern Indiana. Through the years the economy of this two-county area has grown and diversified, so that the stone industry no longer holds the prominent position it once held, but its influence on the economy of earlier years and on the established traditions is inescapable. More than 100 buildings on the Bloomington campus of Indiana University are of limestone from the district, as are nearly all government buildings and countless homes and commercial structures in both Bloomington and Bedford. Oolitic, a small town near the center of the building-stone district, traces its name back to the settlement of the area by immigrant stone workers from England who noticed the similarity of the Salem Limestone to the Portland Oolite, a popular building stone in England. The names of buildings, fraternal organizations, and school mascots testify to the influence of the stone industry on the people. The area has had a rich history because of uncommon properties of a common rock, limestone. The building-stone district has attracted geologists, architects, and laymen from all states and many foreign countries, and through the years we have guided hundreds of people through the quarries and mills. Always we have been warmly received by the owners and the workers. Partly on the basis of these tours and on questions that were asked during the tours, we prepared a guidebook that was first used at the meeting of the North-Central Section of the Geological Society of America in Bloomington on April 12, 1980. This paper has been modified from that coverage (Patton and Carr, 1980).Indiana Department of Natural Resource

It began in ponds and rivers : charting the beginnings of the ecology of fish cognition

But fish cognitive ecology did not begin in rivers and streams. Rather, one of the starting points for work on fish cognitive ecology was work done on the use of visual cues by homing pigeons. Prior to working with fish, Victoria Braithwaite helped to establish that homing pigeons rely not just on magnetic and olfactory cues but also on visual cues for successful return to their home loft. Simple, elegant experiments on homing established Victoria's ability to develop experimental manipulations to examine the role of visual cues in navigation by fish in familiar areas. This work formed the basis of a rich seam of work whereby a fish's ecology was used to propose hypotheses and predictions as to preferred cue use, and then cognitive abilities in a variety of fish species, from model systems (Atlantic salmon and sticklebacks) to the Panamanian Brachyraphis episcopi. Cognitive ecology in fish led to substantial work on fish pain and welfare, but was never left behind, with some of Victoria's last work addressed to determining the neural instantiation of cognitive variation.Publisher PDFPeer reviewe

Farming Systems in the Pastoral Zone of NSW: An Economic Analysis

A ‘broad brush’ picture of farming in the pastoral zone of NSW is presented in this report. The pastoral zone of NSW is characterised by wide variations in climatic conditions, soil type and vegetation species. Hence representative faming system analysis was conducted for three sub-regions - the Upper Darling, the Murray-Darling and Far West. The regions were defined and described in terms of their resources, climate and the nature of agriculture. The main enterprises that farmers choose between were described and whole farm budgets and statements of assets and liabilities for the representative farms were developed. The representative farm models were used to compare traditional Merino based sheep enterprises with alternative sheep enterprises where meat was an important source of income. We found that the farming systems that have evolved in these areas are well suited to their respective environments and that the economic incentives to switch to more meat focussed sheep enterprises were not strong.Western Division, farming systems, economic, analysis, New South Wales, Farm Management, Land Economics/Use, Livestock Production/Industries, Production Economics, Research and Development/Tech Change/Emerging Technologies, Q160,

Cavity-enhanced room-temperature magnetometry using absorption by nitrogen-vacancy centers in diamond

We demonstrate a cavity-enhanced room-temperature magnetic field sensor based on nitrogen-vacancy centers in diamond. Magnetic resonance is detected using absorption of light resonant with the 1042 nm spin-singlet transition. The diamond is placed in an external optical cavity to enhance the absorption, and significant absorption is observed even at room temperature. We demonstrate a magnetic field sensitivity of 2.5 nT/sqrt(Hz), and project a photon shot-noise-limited sensitivity of 70 pT/sqrt(Hz) for a few mW of infrared light, and a quantum projection-noise-limited sensitivity of 250 fT/sqrt(Hz) for the sensing volume of 90 um x 90 um 200 um.Comment: main text 5 pages, supplementary material 3 page

Necrotizing Infection of the Aortic Arch: Reconstruction Utilizing Unusual Extra-anatomic Bypass Grafts to Reroute Cerebral Blood Flow.

Destructive infections of the aortic arch and great vessels are challenging to manage. We describe a novel technique for debranching the right cerebral and upper extremity arteries via composite extra-anatomic bypasses from the femoral artery, with subsequent homograft in-line reconstruction of the arch, in a patient with Staphylococcus sepsis and necrosis of the arch and great vessels

Nonlinear modal coupling in a high-stress doubly-clamped nanomechanical resonator

We present results from a study of the nonlinear intermodal coupling between different flexural vibrational modes of a single high-stress, doubly-clamped silicon nitride nanomechanical beam. The measurements were carried out at 100 mK and the beam was actuated using the magnetomotive technique. We observed the nonlinear behavior of the modes individually and also measured the coupling between them by driving the beam at multiple frequencies. We demonstrate that the different modes of the resonator are coupled to each other by the displacement induced tension in the beam, which also leads to the well known Duffing nonlinearity in doubly-clamped beams.Comment: 15 pages, 7 figure

Geological Surprises at Itezhitezhi Dam, Zambia

An outburst of warm springs together with the development of an extensive area of high pore-water pressures occurred during the first filling of the 50m high earth and rock fill Itezhitezhi Dam on the Kafue River in Zambia. These and other unanticipated events led to extensive geological and hydrogeological investigations that resulted in the implementation of unusual remedial measures. The remedial work was completed before the reservoir reached its full supply level. The dam has since performed successfully. The problems are reviewed in terms of the significance of the site geology. The hydrogeologic problems were found to be caused by the presence of a modified karstic terrane developed on a mineralized, faulted and deeply weathered bedrock of granite and associated rocks. Small differences between the river levels and the piezometric levels in deep porings contributed to a delay in problem identification. The problems encountered and their causes are thought to be without precedent