Microstructure, magneto-transport and magnetic properties of Gd-doped magnetron-sputtered amorphous carbon

The magnetic rare earth element gadolinium (Gd) was doped into thin films of amorphous carbon (hydrogenated \textit{a}-C:H, or hydrogen-free \textit{a}-C) using magnetron co-sputtering. The Gd acted as a magnetic as well as an electrical dopant, resulting in an enormous negative magnetoresistance below a temperature ($T'$). Hydrogen was introduced to control the amorphous carbon bonding structure. High-resolution electron microscopy, ion-beam analysis and Raman spectroscopy were used to characterize the influence of Gd doping on the \textit{a-}Gd$_x$C$_{1-x}$(:H$_y$) film morphology, composition, density and bonding. The films were largely amorphous and homogeneous up to $x$=22.0 at.%. As the Gd doping increased, the $sp^{2}$-bonded carbon atoms evolved from carbon chains to 6-member graphitic rings. Incorporation of H opened up the graphitic rings and stabilized a $sp^{2}$-rich carbon-chain random network. The transport properties not only depended on Gd doping, but were also very sensitive to the $sp^{2}$ ordering. Magnetic properties, such as the spin-glass freezing temperature and susceptibility, scaled with the Gd concentration.Comment: 9 figure

Variation of the density of states in amorphous GdSi at the metal-insulator transition

We performed detailed conductivity and tunneling mesurements on the amorphous, magnetically doped material $\alpha$-Gd$_x$Si$_{1-x}$ (GdSi), which can be driven through the metal-insulator transition by the application of an external magnetic field. Conductivity increases linearly with field near the transition and slightly slower on the metallic side. The tunneling conductance, proportional to the density of states $N(E)$, undergoes a gradual change with increasing field, from insulating, showing a soft gap at low bias, with a slightly weaker than parabolic energy dependence, i.e. $N(E) \sim E^c$, $c \lesssim 2$, towards metallic behavior, with $E^d$, $0.5 \lt d \lt 1$ energy dependence. The density of states at the Fermi level appears to be zero at low fields, as in an insulator, while the sample shows already small, but metal-like conductivity. We suggest a possible explanation to the observed effect.Comment: 6 pages, 6 figure

Atlas Data-Challenge 1 on NorduGrid

The first LHC application ever to be executed in a computational Grid environment is the so-called ATLAS Data-Challenge 1, more specifically, the part assigned to the Scandinavian members of the ATLAS Collaboration. Taking advantage of the NorduGrid testbed and tools, physicists from Denmark, Norway and Sweden were able to participate in the overall exercise starting in July 2002 and continuing through the rest of 2002 and the first part of 2003 using solely the NorduGrid environment. This allowed to distribute input data over a wide area, and rely on the NorduGrid resource discovery mechanism to find an optimal cluster for job submission. During the whole Data-Challenge 1, more than 2 TB of input data was processed and more than 2.5 TB of output data was produced by more than 4750 Grid jobs.Comment: Talk from the 2003 Computing in High Energy Physics and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, 3 ps figure

Most \u3cem\u3eCaenorhabditis elegans\u3c/em\u3e MicroRNAs are Individually Not Essential for Development or Viability

MicroRNAs (miRNAs), a large class of short noncoding RNAs found in many plants and animals, often act to post-transcriptionally inhibit gene expression. We report the generation of deletion mutations in 87 miRNA genes in Caenorhabditis elegans, expanding the number of mutated miRNA genes to 95, or 83% of known C. elegans miRNAs. We find that the majority of miRNAs are not essential for the viability or development of C. elegans, and mutations in most miRNA genes do not result in grossly abnormal phenotypes. These observations are consistent with the hypothesis that there is significant functional redundancy among miRNAs or among gene pathways regulated by miRNAs. This study represents the first comprehensive genetic analysis of miRNA function in any organism and provides a unique, permanent resource for the systematic study of miRNAs

The Science of Open Spaces: Theory and Practice for Conserving Large, Complex Systems. Charles G. Curtin.

The phrase “open spaces,” may bring to mind expansive tracts of prairie, rangeland, or even desert, stretching lonely and unchanged to the horizon. Open spaces also could conjure open oceans or interstitial rural lands between urbanized hubs, dotted with farms, fields, and woodlands. In an abstract sense, open spaces could represent gaps in human understanding or blank spaces on a map. In his book The Science of Open Spaces, landscape ecologist Charles Curtin combines all these perspectives, expanding the definition of “open spaces” to multi-layered and multi-scaled complex systems that are “greater than the sum of their parts.” He populates these vastnesses with the diversity of species, hierarchy of biotic and abiotic interactions, and human social elements that comprise and link open spaces together as social-ecological systems. The Science of Open Spaces provides readers with a roadmap to 21st century land management, where the stakes are high, collaboration is crucial, and profound uncertainty in the face of the complexity often hampers decision-making

Self-care habits among people who inject drugs with skin and soft tissue infections: a qualitative analysis.

BACKGROUND:Injection drug use is on the rise in the USA, and skin and soft tissue infections (SSTI) are a common complication, resulting in significant morbidity and mortality. Due to structural barriers to care-seeking, many people who inject drugs avoid formal care and resort to self-care techniques, but little is known about the nature of these techniques, or more generally about the accuracy or breadth of this population's knowledge of SSTIs. METHODS:Semi-structured qualitative interviews were conducted with 12 people who inject heroin in two metropolitan areas: Sacramento and Boston, USA. RESULTS:These interviews reveal a robust and accurate knowledge base regarding skin infections, including the progression from simple cellulitis to an abscess, and acknowledgment of the possibility of serious infections. Nonetheless, there remains a reticence to seek care secondary to past traumatic experiences. A step-wise approach to self-care of SSTI infections was identified, which included themes of whole-body health, topical applications, use of non-prescribed antibiotics, and incision and drainage by non-medical providers. CONCLUSIONS:The reported SSTI self-care strategies demonstrate resilience and ingenuity, but also raise serious concerns about inappropriate antibiotic consumption and complications of invasive surgical procedures performed without proper training, technique, or materials. Harm reduction agencies and health care providers should work to obviate the need for these potentially dangerous practices by improving healthcare access for this population. In the absence of robust solutions to meet the needs of this population, education materials should be developed to optimize the efficacy and minimize the harms of these practices, while empowering and supporting the autonomy of people who use drugs and providing clear guidance on when self-care should be abandoned in favor of formal medical care

Quasiparticle properties of a coupled quantum wire electron-phonon system

We study leading-order many-body effects of longitudinal optical (LO) phonons on electronic properties of one-dimensional quantum wire systems. We calculate the quasiparticle properties of a weakly polar one dimensional electron gas in the presence of both electron-phonon and electron-electron interactions. The leading-order dynamical screening approximation (GW approximation) is used to obtain the electron self-energy, the quasiparticle spectral function, and the quasiparticle damping rate in our calculation by treating electrons and phonons on an equal footing. Our theory includes effects (within the random phase approximation) of Fermi statistics, Landau damping, plasmon-phonon mode coupling, phonon renormalization, dynamical screening, and impurity scattering. In general, electron-electron and electron-phonon many-body renormalization effects are found to be nonmultiplicative and nonadditive in our theoretical results for quasiparticle properties.Comment: 21 pages, Revtex, 12 figures enclose