Metal-rich T-dwarfs in the Hyades cluster

We present the results of a search for brown dwarfs (BDs) and very low mass (VLM) stars in the 625 Myr-old, metal-rich ([Fe/H]=0.14) Hyades cluster. We performed a deep (I=23, z=22.5) photometric survey over 16 deg$^2$ around the cluster center. We report the discovery of the first 2 BDs in the Hyades cluster, with a spectral type T1 and T2, respectively. Their optical and near-IR photometry, as well as their proper motion, are consistent with them being cluster members. According to models, their mass is about 50 Jupiter masses at an age of 625 Myr. We also report the discovery of 3 new very low mass stellar members and confirm the membership of 15 others

A deep, wide-field search for substellar members in NGC 2264

We report the first results of our ongoing campaign to discover the first brown dwarfs (BD) in NGC 2264, a young (3 Myr), populous star forming region for which our optical studies have revealed a very high density of potential candidates - 236 in $<$ 1 deg$^2$ - from the substellar limit down to at least $\sim$ 20 M$_{\rm Jup}$ for zero reddening. Candidate BD were first selected using wide field ($I,z$) band imaging with CFH12K, by reference to current theoretical isochrones. Subsequently, 79 (33%) of the $I,z$ sample were found to have near-infrared 2MASS photometry ($JHK_s$ $\pm$ 0.3 mag. or better), yielding dereddened magnitudes and allowing further investigation by comparison with the location of NextGen and DUSTY isochrones in colour-colour and colour-magnitude diagrams involving various combinations of $I$,$J$,$H$ and $K_s$. We discuss the status and potential substellarity of a number of relatively unreddened (A$_{\rm v}$ $<$ 5) likely low-mass members in our sample, but in spite of the depth of our observations in $I,z$, we are as yet unable to unambiguously identify substellar candidates using only 2MASS data. Nevertheless, there are excellent arguments for considering two faint (observed $I$ $\sim$ 18.4 and 21.2) objects as cluster candidates with masses respectively at or rather below the hydrogen burning limit. More current candidates could be proven to be cluster members with masses around 0.1 M$_{\odot}$ {\it via} gravity-sensitive spectroscopy, and deeper near-infrared imaging will surely reveal a hitherto unknown population of young brown dwarfs in this region, accessible to the next generation of deep near-infrared surveys.Comment: 10 pages, 12 figures, accepted by A&

Free-stream noise and transition measurements on a cone in a Mach 3.5 pilot low-disturbance tunnel

A small scale Mach 3.5 wind tunnel incorporating certain novel design features and intended for boundary-layer-transition research has been tested. The free stream noise intensities and spectral distributions were determined throughout the test section for several values of unit Reynolds number and for nozzle boundary layer bleed on and off. The boundary layer transition location on a slender cone and the response of this to changes in the noise environment were determined. Root mean square free stream noise levels ranged from less than one tenth up to values approaching those for conventional nozzles, with the lowest values prevailing at upstream locations within the nozzle. For low noise conditions, cone transition Reynolds numbers were in the range of those for free flight; whereas for high noise conditions, they were in the range of those in conventional tunnels

Calculation of three-dimensional compressible laminar and turbulent boundary flows. Three-dimensional compressible boundary layers of reacting gases over realistic configurations

A three-dimensional boundary-layer code was developed for particular application to realistic hypersonic aircraft. It is very general and can be applied to a wide variety of boundary-layer flows. Laminar, transitional, and fully turbulent flows of compressible, reacting gases are efficiently calculated by use of the code. A body-oriented orthogonal coordinate system is used for the calculation and the user has complete freedom in specifying the coordinate system within the restrictions that one coordinate must be normal to the surface and the three coordinates must be mutually orthogonal

Fungal-specific PCR primers developed for analysis of the ITS region of environmental DNA extracts

BACKGROUND: The Internal Transcribed Spacer (ITS) regions of fungal ribosomal DNA (rDNA) are highly variable sequences of great importance in distinguishing fungal species by PCR analysis. Previously published PCR primers available for amplifying these sequences from environmental samples provide varying degrees of success at discriminating against plant DNA while maintaining a broad range of compatibility. Typically, it has been necessary to use multiple primer sets to accommodate the range of fungi under study, potentially creating artificial distinctions for fungal sequences that amplify with more than one primer set. RESULTS: Numerous sequences for PCR primers were tested to develop PCR assays with a wide range of fungal compatibility and high discrimination from plant DNA. A nested set of 4 primers was developed that reflected these criteria and performed well amplifying ITS regions of fungal rDNA. Primers in the 5.8S sequence were also developed that would permit separate amplifications of ITS1 and ITS2. A range of basidiomycete fruiting bodies and ascomycete cultures were analyzed with the nested set of primers and Restriction Fragment Length Polymorphism (RFLP) fingerprinting to demonstrate the specificity of the assay. Single ectomycorrhizal root tips were similarly analyzed. These primers have also been successfully applied to Quantitative PCR (QPCR), Length Heterogeneity PCR (LH-PCR) and Terminal Restriction Fragment Length Polymorphism (T-RFLP) analyses of fungi. A set of wide-range plant-specific primers were developed at positions corresponding to one pair of the fungal primers. These were used to verify that the host plant DNA was not being amplified with the fungal primers. CONCLUSION: These plant primers have been successfully applied to PCR-RFLP analyses of forest plant tissues from above- and below-ground samples and work well at distinguishing a selection of plants to the species level. The complete set of primers was developed with an emphasis on discrimination between plant and fungal sequences and should be particularly useful for studies of fungi where samples also contain high levels of background plant DNA, such as verifying ectomycorrhizal morphotypes or characterizing phylosphere communities

Chemical Modification of Crumb Rubber to Increase Its Bonding with Concrete

The hydrophilicity of crumb rubber was increased with wet chemical modification and added to concrete to increase its adhesion with concrete, consequently the compressive strength relative to that of concrete with untreated rubber. Other modification methods were tested on crumb rubber and rubber sheets to yield an increase in hydrophilicity. Certain tests were less reliable for powder testing or tedious and time consuming and concrete materials and rubber may not be homogeneous. For wet chemical modification, several approaches were attempted. First, crumb rubber was soaked in 5% sodium hydroxide, 5% potassium permanganate and saturated sodium bisulfite, tested for hydrophilicity using Sessile Drop, Washburn Capillary Rise and hydrophobic partitioning and added to concrete cylinders tested for compressive strength. The results from the Sessile Drop method show that water spread out and disappeared over the modified rubber indicating hydrophilicity. The results from the Washburn Capillary Rise show that the modified rubber has a contact angle of 89.4 ± 0.02°. The results from the Hydrophobic Partitioning method show that rubber became somewhat more miscible with water. Results of compressive strength testing show that the compressive strength of concrete containing unmodified rubber was 40% lower than that of regular concrete but the compressive strength of concrete containing modified rubber was 2% lower than that concrete containing unmodified rubber. Second, crumb rubber was soaked in 5% sodium hydroxide for 24 hours or stirred in saturated sodium hydroxide for 20 minutes and tested for hydrophilicity using Sessile Drop or hydrophobic partitioning. The results from the Sessile Drop method show that unmodified crumb rubber has a contact angle of 121.8 ± 13.2°, crumb rubber soaked in 5 % NaOH for 24 hours has a contact angle of 115.8 ± 8.0° and crumb rubber stirred in saturated NaOH for 20 minutes has a contact angle of 121.5 ± 8.1°. Results from the Hydrophobic Partitioning method show that unmodified rubber and rubber soaked in 5 % NaOH for 24 hours are not miscible with water at all (rubber soaked in saturated NaOH was not tested). To gain some basic understanding on how rubber can be affected by different treatment methods, rubber sheets were modified with sodium hydroxide, potassium permanganate, sodium bisulfite, combinations of the three, as well as by ultraviolet radiation or plasma radiation. Water contact angles on the treated rubber sheets were measured using the sessile drop method. The results show that rubber sheets were made somewhat more hydrophilic with the combinations of sodium hydroxide, potassium permanganate and sodium bisulfite treatments and significantly with UV or plasma but not with sodium hydroxide alone

Antimicrobial Susceptibilities of Aerobic Isolates from Respiratory Samples of Young New Zealand Horses

3rd Annual IEEE Energy Conversion Congress and Exposition, ECCE 2011, Phoenix, AZ, 17-22 September 2011This paper presents a method of mitigating the transient overshoots of DC-DC converters operating with large load disturbances. The method involves a small auxiliary power circuit with a complementary control scheme that provides a smooth absorption and release of excess energy from and to the main DC-DC converter in the events of large load changes. This control mechanism interactively mitigates the large transient overshoots which would otherwise appear at the converter output. Since the control scheme involves an adjustable-energy-storage feature, the proposed solution is effective for any level of step-load change within a pre-specified range.Department of Electronic and Information EngineeringRefereed conference pape

Weak measurement takes a simple form for cumulants

A weak measurement on a system is made by coupling a pointer weakly to the system and then measuring the position of the pointer. If the initial wavefunction for the pointer is real, the mean displacement of the pointer is proportional to the so-called weak value of the observable being measured. This gives an intuitively direct way of understanding weak measurement. However, if the initial pointer wavefunction takes complex values, the relationship between pointer displacement and weak value is not quite so simple, as pointed out recently by R. Jozsa. This is even more striking in the case of sequential weak measurements. These are carried out by coupling several pointers at different stages of evolution of the system, and the relationship between the products of the measured pointer positions and the sequential weak values can become extremely complicated for an arbitrary initial pointer wavefunction. Surprisingly, all this complication vanishes when one calculates the cumulants of pointer positions. These are directly proportional to the cumulants of sequential weak values. This suggests that cumulants have a fundamental physical significance for weak measurement