k-core organization of complex networks

We analytically describe the architecture of randomly damaged uncorrelated networks as a set of successively enclosed substructures -- k-cores. The k-core is the largest subgraph where vertices have at least k interconnections. We find the structure of k-cores, their sizes, and their birth points -- the bootstrap percolation thresholds. We show that in networks with a finite mean number z_2 of the second-nearest neighbors, the emergence of a k-core is a hybrid phase transition. In contrast, if z_2 diverges, the networks contain an infinite sequence of k-cores which are ultra-robust against random damage.Comment: 5 pages, 3 figure

Quantifying mixed-state quantum entanglement by optimal entanglement witness

We develop an approach of quantifying entanglement in mixed quantum states by the optimal entanglement witness operator. We identify the convex set of mixed states for which a single witness provides the exact value of an entanglement measure, and show that the convexity, properties, and symmetries of entanglement or of a target state considerably fix the form of the optimal witness. This greatly reduces difficulty in computing and experimentally determining entanglement measures. As an example, we show how to experimentally quantify bound entanglement in four-qubit noisy Smolin states and three-qubit Greenberger-Horne-Zeilinger (GHZ) entanglement under white noise. For general measures and states, we provide a numerical method to efficiently optimize witness.Comment: Supplemental material is include

Increased resistance to stress corrosion of aluminum alloys

Stress corrosion resistance is increased by distorting surface grain-boundary structure and by interrupting the corrosion and stress corrosion. The first is accomplished by machining or shot peening and the second by removal from and later reexposure to the corrosive environment

Dual band combiner for horn antenna

A corrugated horn antenna, adapted to be coupled to a waveguide at its apex for X-band excitation is further adapted to be connected to waveguides through a circumferential slot for S-band excitation at four distinct phases selected for the desired S-band polarization. The circumferential slot is positioned along the axial length of the horn for good impedance matching and is provided with an X-band choke in the form of two concentric choke slots. For further improvement in impedance matching, the second (outer) choke slot is divided by plugs into four segments that coincide with waveguide ports for the four distinct phases of the S-band

Women's experiences of increasing subjective well-being in CFS/ME through leisure-based arts and crafts activities: A qualitative study

This is the author's accepted manuscript. The final published article is available from the link below. Copyright © 2008 Informa Plc.Purpose. To understand the meanings of art-making among a group of women living with the occupational constraints and stigma of CFS/ME. The study explored their initial motives for art-making, and then examined how art-making had subsequently influenced their subjective well-being. Method. Ten women with CFS/ME were interviewed; three provided lengthy written accounts to the interview questions. Findings. Illness had resulted in devastating occupational and role loss. Participants took many years to make positive lifestyle changes. Art-making was typically discovered once participants had accepted the long-term nature of CFS/ME, accommodated to illness, and reprioritized occupations. Several factors then attracted participants specifically to art-making. It was perceived as manageable within the constraints of ill-health. Participants also tended to be familiar with craft skills; had family members interested in arts and crafts, and some desired a means to express grief and loss. Once established as a leisure activity, art-making increased subjective well-being mainly through providing increased satisfaction in daily life, positive self-image, hope, and contact with the outside world. Participants recommended provision of occupational/recreational counselling earlier in the illness trajectory. Conclusions. Creative art-making occurred as part of a broader acceptance and adjustment process to CFS/ME, and allowed some psychological escape from a circumscribed lifeworld