Radio Emission Associated with Ultraluminous X-ray Sources in the Galaxy Merger NGC 3256

We present new 6, 3.6, and 2 cm VLA radio observations of the nearby merger system NGC 3256, with resolutions of ~100 pc, which reveal compact radio sources embedded in more diffuse emission at all three wavelengths. The two radio nuclei are partially resolved, but the two dominant compact sources that remain coincide with the two most powerful compact Ultraluminous X-ray sources (ULXs) recently reported by Lira et al. The radio/X-ray ratios for these two sources are too high by factors of >100-1000 to be normal X-ray binaries. However, their radio and X-ray powers and ratios are consistent with low-luminosity active galactic nuclei (LLAGNs), and optical emission lines suggest the presence of a nuclear disk around the northern nucleus. If the two nuclear ULXs are LLAGNs, their associated black holes are separated by only \~1kpc, about 6 times closer to one another than those found recently in the merger galaxy NGC 6240. A third ULX on the outskirts of the merger is also a radio source, and probably is a collection of supernova remnants. The remaining ULXs are not coincident with any source of compact radio emission, and are consistent with expectations for beamed X-ray binaries or intermediate-mass black holes.Comment: Accepted for ApJ (10 pages, 5 figures

The Challenges of Organizational Factors in Collaborative Artificial Intelligence Projects

Despite the current popularity of AI and a steady increase in publications over time, few studies have investigated artificial intelligence (AI) in public contexts. As a result, assumptions about the drivers, challenges, and impacts of AI in government are far from conclusive. By using a case study that involves a large research university in England and two different county councils in a multi-year collaborative project around AI, we study the challenges that interorganizational collaborations face in adopting AI tools and implementing organizational routines to address them. Our findings reveal the most important challenges facing such collaborations: a resistance to sharing data, due to privacy and security concerns; insufficient understanding of the required and available data; a lack of alignment between project interests and expectations around data sharing; and a lack of engagement across organizational hierarchy. Organizational routines capable of overcoming such challenges include working on-site, presenting the benefits of data sharing, re-framing problems, designating joint appointments and boundary spanners, and connecting participants in the collaboration at all levels around project design and purpose

Reorientation Transition in Single-Domain (Ga,Mn)As

We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy fields in (Ga,Mn)As results in a magnetization reorientation transition and an anisotropic AC susceptibility which is fully consistent with a simple single domain model. The uniaxial and biaxial anisotropy constants vary respectively as the square and fourth power of the spontaneous magnetization across the whole temperature range up to T_C. The weakening of the anisotropy at the transition may be of technological importance for applications involving thermally-assisted magnetization switching.Comment: 4 pages, 4 figure

Optical orientation of spins in GaAs:Mn/AlGaAs quantum wells via impurity-to-band excitation

The paper reports optical orientation experiments performed in the narrow GaAs/AlGaAs quantum wells doped with Mn. We experimentally demonstrate a control over the spin polarization by means of the optical orientation via the impurity-to-band excitation and observe a sign inversion of the luminescence polarization depending on the pump power. The g factor of a hole localized on the Mn acceptor in the quantum well was also found to be considerably modified from its bulk value due to the quantum confinement effect. This finding shows the importance of the local environment on magnetic properties of the dopants in semiconductor nanostructures

Strain dependence of the Mn anisotropy in ferromagnetic semiconductors observed by x-ray magnetic circular dichroism

We demonstrate sensitivity of the Mn 3d valence states to strain in the ferromagnetic semiconductors (Ga,Mn)As and (Al,Ga,Mn)As, using x-ray magnetic circular dichroism (XMCD). The spectral shape of the Mn $L_{2,3}$ XMCD is dependent on the orientation of the magnetization, and features with cubic and uniaxial dependence are distinguished. Reversing the strain reverses the sign of the uniaxial anisotropy of the Mn $L_3$ pre-peak which is ascribed to transitions from the Mn 2p core level to p-d hybridized valence band hole states. With increasing carrier localization, the $L_3$ pre-peak intensity increases, indicating an increasing 3d character of the hybridized holes.Comment: 4 pages plus 2 figures, accepted for publication in Physical Review

Overcoming the Challenges of Collaboratively Adopting Artificial Intelligence in the Public Sector

Despite the current popularity of artificial intelligence (AI) and a steady increase in publications over time, few studies have investigated AI in public contexts. As a result, assumptions about the drivers, challenges, and impacts of AI in government are far from conclusive. By using a case study that involves a large research university in England and two different county councils in a multiyear collaborative project around AI, we study the challenges that interorganizational collaborations face in adopting AI tools and implementing organizational routines to address them. Our findings reveal the most important challenges facing such collaborations: a resistance to sharing data due to privacy and security concerns, insufficient understanding of the required and available data, a lack of alignment between project interests and expectations around data sharing, and a lack of engagement across organizational hierarchy. Organizational routines capable of overcoming such challenges include working on-site, presenting the benefits of data sharing, reframing problems, designating joint appointments and boundary spanners, and connecting participants in the collaboration at all levels around project design and purpose

Search For Hole Mediated Ferromagnetism In Cubic (Ga,Mn)N

Results of magnetisation measurements on p-type zincblende-(Ga,Mn)N are reported. In addition to a small high temperature ferromagnetic signal, we detect ferromagnetic correlation among the remaining Mn ions, which we assign to the onset of hole-mediated ferromagnetism in (Ga,Mn)N.Comment: 2 pages, 1 figure, proc. ICPS 27, Flagstaff '0