Description and research capabilities of the Langley Low Frequency Noise Facility

Description and research capabilities of low frequency noise facilit

Description of Langley low-frequency noise facility and study of human response to noise frequencies below 50 cps

Test facility for determining human performance in very low frequency noise environment - physiological and psychological response

Discovery of a Large-scale Wall in the Direction of Abell 22

We report on the discovery of a large-scale wall in the direction of Abell 22. Using photometric and spectroscopic data from the Las Campanas Observatory and Anglo-Australian Telescope Rich Cluster Survey, Abell 22 is found to exhibit a highly unusual and striking redshift distribution. We show that Abell 22 exhibits a foreground wall-like structure by examining the galaxy distributions in both redshift space and on the colour-magnitude plane. A search for other galaxies and clusters in the nearby region using the 2dF Galaxy Redshift Survey database suggests that the wall-like structure is a significant large-scale, non-virialized filament which runs between two other Abell clusters either side of Abell 22. The filament stretches over at least >40 Mpc in length and 10 Mpc in width at the redshift of Abell 22.Comment: 6 pages, 4 figures, accepted for publication in MNRAS letter

AX J0049.4-7323 - a close look at a neutron star interacting with a circumstellar disk

Detailed evidence on the system AX J0049.4-7323 is presented here to show how the passage of the neutron star in the binary system disrupts the circumstellar disk of the mass donor Be star. A similar effect is noted in three other Be/X-ray binary systems. Together the observational data should provide valuable tools for modelling these complex interactions.Comment: 4 pages, accepted for publication in MNRA

Experiences of a transdiagnostic group, the Take Control Course, for clients with common mental health problems : a qualitative study

Objectives Despite the promising effectiveness findings for transdiagnostic groups, studies have not explored clients' experiences. There is a risk that clients could perceive that the content of transdiagnostic groups is not sufficiently tailored to their specific problems. Our aims were to examine whether a brief transdiagnostic group, the Take Control Course (TCC), was acceptable to participants and to explore participants' perceptions of psychological change. Methods Qualitative data were collected via 12 semistructured, in‐depth interviews. Data collection and thematic analysis were concurrent and iterative. Results Three superordinate themes were identified: “Style and format,” “Control and flexibility,” and “Change.” The flexible group format was appreciated, as participants felt able to engage at their own pace and adapt relevant aspects. Greater clarity regarding what was within participants' control reduced distress and enabled effective pursuit of valued goals. Participants described significant (predominantly gradual) changes, including substantial improvements within relationships. Conclusions The transdiagnostic format did not prevent participants experiencing the TCC as individually relevant. The flexibility and consistent theoretical framework seemed to contribute to this. The results indicated that greater consideration of control and mindfulness allowed greater cognitive flexibility, an ability to reprioritize and let go of unhelpful habits, which better enabled participants to meet their goals. Implications for group therapy include (a) clearly explaining the format of such groups to clients and (b) providing flexibility in the way the group is delivered where possible. Additional qualitative studies of transdiagnostic groups are required to establish if themes generalize to other transdiagnostic groups

A Differential X-Ray Gunn-Peterson Test Using a Giant Cluster Filament

Using CCD detectors onboard the forthcoming X-ray observatories Chandra and XMM, it is possible to devise a measurement of the absolute density of heavy elements in the hypothetical warm gas filling intercluster space. This gas may be the largest reservoir of baryonic matter in the Universe, but even its existence has not been proven observationally at low redshifts. The proposed measurement would make use of a unique filament of galaxy clusters spanning over 700 Mpc (0.1<z<0.2) along the line of sight in a small area of the sky in Aquarius. The surface density of Abell clusters there is more than 6 times the sky average. It is likely that the intercluster matter column density is enhanced by a similar factor, making its detection feasible under certain optimistic assumptions about its density and elemental abundances. One can compare photoabsorption depth, mostly in the partially ionized oxygen edges, in the spectra of clusters at different distances along the filament, looking for a systematic increase of depth with the distance. The absorption can be measured by the same detector and through the same Galactic column, hence the differential test. A CCD moderate energy resolution (about 100 eV) is adequate for detecting an absorption edge at a known redshift.Comment: Latex, 4 pages, 3 figures, uses emulateapj.sty. ApJ Letters in pres

An infrared survey of brightest cluster galaxies: Paper I

We report on an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies with optical line emission. These galaxies are located in the cores of X-ray luminous clusters selected from the ROSAT All-Sky Survey. We find that about half of these sources have a sign of excess infrared emission; 22 objects out of 62 are detected at 70 microns, 18 have 8 to 5.8 micron flux ratios above 1.0 and 28 have 24 to 8 micron flux ratios above 1.0. Altogether 35 of 62 objects in our survey exhibit at least one of these signs of infrared excess. Four galaxies with infrared excesses have a 4.5/3.6 micron flux ratio indicating the presence of hot dust, and/or an unresolved nucleus at 8 microns. Three of these have high measured [OIII](5007A)/Hbeta flux ratios suggesting that these four, Abell 1068, Abell 2146, and Zwicky 2089, and R0821+07, host dusty active galactic nuclei (AGNs). 9 objects (including the four hosting dusty AGNs) have infrared luminosities greater than 10^11 L_sol and so can be classified as luminous infrared galaxies (LIRGs). Excluding the four systems hosting dusty AGNs, the excess mid-infrared emission in the remaining brightest cluster galaxies is likely related to star formation.Comment: accepted for publication in ApJ

Metallic phase of the quantum Hall effect in four-dimensional space

We study the phase diagram of the quantum Hall effect in four-dimensional (4D) space. Unlike in 2D, in 4D there exists a metallic as well as an insulating phase, depending on the disorder strength. The critical exponent $\nu\approx 1.2$ of the diverging localization length at the quantum Hall insulator-to-metal transition differs from the semiclassical value $\nu=1$ of 4D Anderson transitions in the presence of time-reversal symmetry. Our numerical analysis is based on a mapping of the 4D Hamiltonian onto a 1D dynamical system, providing a route towards the experimental realization of the 4D quantum Hall effect.Comment: 4+epsilon pages, 3 figure