10,070 research outputs found
Role of interactions in 87Rb-40K Bose-Fermi mixtures in a 3d optical lattice
We investigate the effect of interspecies interaction on a degenerate mixture
of bosonic 87Rb and fermionic 40K atoms in a three-dimensional optical lattice
potential. Using a Feshbach resonance, the 87Rb-40K interaction is tuned over a
wide range. Through an analysis of the 87Rb momentum distribution, we find a
pronounced asymmetry between strong repulsion and strong attraction. In the
latter case, the Bose-Hubbard parameters are renormalized due to self-trapping,
leading to a marked shift in the superfluid to Mott insulator transition with
increasing Bose-Fermi interaction.Comment: 5 pages, 4 figure
The final two redshifts for radio sources from the equatorial BRL sample
Best, Rottgering and Lehnert (1999, 2000a) defined a new sample of powerful
radio sources from the Molonglo Reference Catalogue, for which redshifts were
compiled or measured for 177 of the 178 objects. For the final object,
MRC1059-010 (3C249), the host galaxy is here identified using near-infrared
imaging, and the redshift is determined from VLT spectroscopy. For one other
object in the sample, MRC0320+053 (4C05.14), the literature redshift has been
questioned: new spectroscopic observations of this object are presented,
deriving a corrected redshift. With these two results, the spectroscopic
completeness of this sample is now 100%.
New redshifts are also presented for PKS0742+10 from the Wall & Peacock 2.7
GHz catalogue, and PKS1336+003 from the Parkes Selected Regions. PKS0742+10
shows a strong neutral hydrogen absorption feature in its Lyman-alpha emission
profile.Comment: 4 pages. LaTeX. Accepted for publication in MNRA
The Malice of Maladaptation: Is Teleworking Enabling Behavioural Addiction?
Whilst the concept of addiction is predominantly related to substance abuse in academic literature, there is growing literature around individuals engaging in behavioural addictive practices such as gaming, gambling, food, sex, and work. This paper explores whether individuals who telework are more likely to exhibit maladaptive behaviours and consequently engage in non-substance based addictive practices. This paper aims to address both societal stigmas and gaps in existing current literature by identifying that behavioural addictions share the same patterns to substance-based abuse so that organisations can provide effective intervention and support strategies for employees
The host galaxies of radio-loud AGN: mass dependencies, gas cooling and AGN feedback
The properties of the host galaxies of a well-defined sample of 2215
radio-loud AGN with redshifts 0.03 < z < 0.3, defined from the SDSS, are
investigated. These are predominantly low radio luminosity sources, with 1.4GHz
luminosities of 10^23 to 10^25 W/Hz. The fraction of galaxies that host
radio-loud AGN with L(1.4GHz) > 10^23 W/Hz is a strong function of stellar
mass, rising from nearly zero below a stellar mass of 10^10 Msun to more than
30% at 5x10^11 Msun. The integral radio luminosity function is derived in six
ranges of stellar and black hole mass. Its shape is very similar in all of
these ranges and can be well fitted by a broken power-law. Its normalisation
varies strongly with mass, as M_*^2.5 or M_BH^1.6; this scaling only begins to
break down when the predicted radio-loud fraction exceeds 20-30%. There is no
correlation between radio and emission line luminosities for the radio-loud AGN
in the sample and the probability that a galaxy of given mass is radio-loud is
independent of whether it is optically classified as an AGN. The host galaxies
of the radio-loud AGN have properties similar to those of ordinary galaxies of
the same mass.
All of these findings support the conclusion that the optical AGN and low
radio luminosity AGN phenomena are independent and are triggered by different
physical mechanisms. Intriguingly, the dependence on black hole mass of the
radio-loud AGN fraction mirrors that of the rate at which gas cools from the
hot atmospheres of elliptical galaxies. It is speculated that gas cooling
provides a natural explanation for the origin of the radio-loud AGN activity,
and it is argued that AGN heating could plausibly balance the cooling of the
gas over time. [Abridged]Comment: Accepted for publication in MNRAS. LaTeX, 16 pages. Figure 10 is in
colou
Electrically Small Supergain Arrays
The theory, computer simulations, and experimental measurements are presented
for electrically small two-element supergain arrays with near optimal endfire
gains of 7 dB. We show how the difficulties of narrow tolerances, large
mismatches, low radiation efficiencies, and reduced scattering of electrically
small parasitic elements are overcome by using electrically small resonant
antennas as the elements in both separately driven and singly driven
(parasitic) two-element electrically small supergain endfire arrays. Although
rapidly increasing narrow tolerances prevent the practical realization of the
maximum theoretically possible endfire gain of electrically small arrays with
many elements, the theory and preliminary numerical simulations indicate that
near maximum supergains are also achievable in practice for electrically small
arrays with three (and possibly more) resonant elements if the decreasing
bandwidth with increasing number of elements can be tolerated.Comment: 10 pages, 11 figures, submitted to IEEE Transactions on Antennas and
Propagation (December 2006
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Collagen-Fibrinogen Lyophilised Scaffolds for Soft Tissue Regeneration
A significant body of research has considered collagen as a scaffold material for soft tissue regeneration. The main structural component of extra-cellular matrix (ECM), collagenâs advantages over synthetic polymers are numerous. However, for applications where higher stiffness and stability are required, significant cross-linking may affect bioactivity. A carbodiimide (EDC) cross-linking route consumes carboxylate groups that are key to collagenâs essential cell recognition motifs (GxOGER). Fibrinogen was considered as a promising additive as it plays a key role in the process of wound repair and contains RGD integrin binding sites which bind to a variety of cells, growth factors and cytokines. Fibrinogenâs binding sites however, also contain the same carboxylate groups as collagen. We have successfully produced highly interconnected, porous collagen-fibrinogen scaffolds using a lyophilisation technique and micro-computed tomography demonstrated minimal influence of either fibrinogen content or cross-linking concentration on the scaffold structure. The specific biological effect of fibrinogen additions into cross-linked collagen are considered by using films as a model for the struts of bulk scaffolds. By considering various additions of fibrinogen to the collagen film with increasing degrees of cross-linking, this study demonstrates a significant biological advantage with fibrinogen addition across the cross-linking concentrations typically applied to collagen-based scaffolds.The authors wish to acknowledge the support of the European Research Council for the Advanced Grant 320598 awarded to REC and the EPSRC for the Established Career Fellowship EP/N019938/1 awarded to REC and SMB. They also wish to acknowledge funding for DB from the Peoples Programme of the EU 7th Framework Programme (RAE no: PHF-GA-2013-624904)
DIFFERENT WEIGHT TRANSFER PATTERNS IN GOLF
The aim of this study was to determine if weight transfer swing styles exist in the golf swing. 40 golfers performed swings using a driver while standing on two force plates. Centre of pressure, used to indicate weight transfer, was normalized to foot position and quantified at eight swing events. Cluster analysis indicated that two major swing styles existed; a Front Foot style and a Reverse style. Both styles were similar from Takeaway to Early Downswing. Then, while the Front Foot group moved weight towards the front foot during the downswing, the Reverse group moved weight back towards the back foot. In the heel to toe direction, the Front Foot group hit from a mid-foot position, while the Reverse group hit with weight near the toes at ball contact. Cluster analysis is a useful tool for identifying different styles
The bridge between social identity and community capital on the path to recovery and desistance
It has long been recognised that changes in social networks (and the underpinning changes in personal and social identity) are strong predictors of both desistance from crime and recovery from substance use. Building on existing work attempting to measure and shift social networks and transitions to prosocial groups, the current study provides pilot data from prisoners and family members about a visualisation technique widely used in specialist addiction treatment (node-link mapping) to map opportunities for linkage to prosocial groups and networks. The data presented in the paper are from a small-scale feasibility pilot. This suggests both bonding and bridging capital in prisoner populations due for release and the diversity of community capital opportunities that exists in this population. The implications of this work are significant for substance users and offenders pending return to the community, and has implications around resettlement and reintegration support for probation staff in prisons and in the community. The paper emphasises the importance of mapping connectedness as a key component of planning for reintegration back into the community for those working with offenders who are aspiring to achieve desistance and recovery
Noncontact atomic force microscopy simulator with phase-locked-loop controlled frequency detection and excitation
A simulation of an atomic force microscope operating in the constant
amplitude dynamic mode is described. The implementation mimics the electronics
of a real setup including a digital phase-locked loop (PLL). The PLL is not
only used as a very sensitive frequency detector, but also to generate the
time-dependent phase shifted signal driving the cantilever. The optimum
adjustments of individual functional blocks and their joint performance in
typical experiments are determined in detail. Prior to testing the complete
setup, the performances of the numerical PLL and of the amplitude controller
were ascertained to be satisfactory compared to those of the real components.
Attention is also focused on the issue of apparent dissipation, that is, of
spurious variations in the driving amplitude caused by the nonlinear
interaction occurring between the tip and the surface and by the finite
response times of the various controllers. To do so, an estimate of the minimum
dissipated energy that is detectable by the instrument upon operating
conditions is given. This allows us to discuss the relevance of apparent
dissipation that can be conditionally generated with the simulator in
comparison to values reported experimentally. The analysis emphasizes that
apparent dissipation can contribute to the measured dissipation up to 15% of
the intrinsic dissipated energy of the cantilever interacting with the surface,
but can be made negligible when properly adjusting the controllers, the PLL
gains and the scan speed. It is inferred that the experimental values of
dissipation usually reported in the literature cannot only originate in
apparent dissipation, which favors the hypothesis of "physical" channels of
dissipation
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