Third edge for a graphene nanoribbon: A tight-binding model calculation

The electronic and transport properties of an extended linear defect embedded in a zigzag nanoribbon of realistic width are studied, within a tight binding model approach. Our results suggest that such defect profoundly modify the properties of the nanoribbon, introducing new conductance quantization values and modifying the conductance quantization thresholds. The linear defect along the nanoribbon behaves as an effective third edge of the system, which shows a metallic behavior, giving rise to new conduction pathways that could be used in nanoscale circuitry as a quantum wire.Comment: 6 pages, 6 figures. Two new figures and a few references adde

Pengaruh Bentuk dan Dimensi Tapak Pondasi terhadap Daya Dukung Pondasi Dangkal Akibat Beban Aksial pada Tanah Pasir

The load distribution of shallow foundation spread out along the width of the foundation. Ultimate bearing capacity is defined as the maximum load that can be supported by the footing. Some form of shallow foundation were square, rectangular and circular shapes were they made to analyze the influence of the foundation over the same area of the shallow foundation bearing capacity due to axial loads on sandy soil. Variations foundation area of 100 cm2, 150 cm2 and 200 cm2. In the same area, the square shape can withstand greater load than in rectangular and circular shapes. Addition area will make 50-100% in weight-bearing capacity increased from 102,016 to 157,661% for squares, 135,751 to 228,497% for the rectangle and circle 187,413 to 341.259%. There are differences in the results of observation and empirical formula. Shape factors of squares and circles according to Mayerhof, Vesic and Hansen are the same. So, Terzaghi`s formula was similiar phenomenom with this research

Topology of Cell-Aggregated Planar Graphs

We present new algorithm for growth of non-clustered planar graphs by aggregation of cells with given distribution of size and constraint of connectivity k=3 per node. The emergent graph structures are controlled by two parameters--chemical potential of the cell aggregation and the width of the cell size distribution. We compute several statistical properties of these graphs--fractal dimension of the perimeter, distribution of shortest paths between pairs of nodes and topological betweenness of nodes and links. We show how these topological properties depend on the control parameters of the aggregation process and discuss their relevance for the conduction of current in self-assembled nanopatterns.Comment: 8 pages, 5 figure

Nano-wires with surface disorder: Giant localization lengths and quantum-to-classical crossover

We investigate electronic quantum transport through nano-wires with one-sided surface roughness. A magnetic field perpendicular to the scattering region is shown to lead to exponentially diverging localization lengths in the quantum-to-classical crossover regime. This effect can be quantitatively accounted for by tunneling between the regular and the chaotic components of the underlying mixed classical phase space.Comment: 4 pages, 3 figures; final version (including added references

Transport inefficiency in branched-out mesoscopic networks: An analog of the Braess paradox

We present evidence for a counter-intuitive behavior of semiconductor mesoscopic networks that is the analog of the Braess paradox encountered in classical networks. A numerical simulation of quantum transport in a two-branch mesoscopic network reveals that adding a third branch can paradoxically induce transport inefficiency that manifests itself in a sizable conductance drop of the network. A scanning-probe experiment using a biased tip to modulate the transmission of one branch in the network reveals the occurrence of this paradox by mapping the conductance variation as a function of the tip voltage and position.Comment: 2nd version with minor stylistic corrections. To appear in Phys. Rev. Lett.: Editorially approved for publication 6 January 201

Prevalence of isolates with reduced glycopeptide susceptibility in orthopedic device-related infections due to methicillin-resistant Staphylococcus aureus

We evaluated, by an improved susceptibility testing method, the prevalence and significance of low-level glycopeptide resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolates, which belonged to a previously described, retrospective cohort of patients treated for orthopedic device-related infections (ODRI) at the Geneva University Hospital between 2000 and 2008. Fifty-seven individual or multiple isolates were retrieved from 41 ODRI patients for glycopeptide susceptibility and clonality studies, including 20 patients with prosthetic joint (PJ) and 21 with osteosynthesis (OS) MRSA infections. Low-level glycopeptide resistance was detected by elevated teicoplanin or/and vancomycin minimum inhibitory concentrations (MICs ≥4mg/L), as determined by a previously validated combination of macrodilution and agar dilution assays of improved sensitivity. MRSA isolates with elevated teicoplanin MICs were detected in 20/41 (49%) ODRI patients at the onset or during the course of glycopeptide therapy, namely, in 10 of 20 patients with PJ and 10 of 21 patients with OS infections. Only one isolate developed a concomitant increase in vancomycin MIC during therapy. 13/20 (65%) glycopeptide-intermediate S. aureus (GISA)-infected patients, including 7/10 (70%) with PJ and 6/10 (60%) with OS, experienced treatment failure. In contrast, therapy failed in only 5/21 (24%) ODRI patients with non-GISA isolates (p = 0.012), including 2/10 (20%) with PJ and 3/11 (27%) with OS infections. The emergence of low-level teicoplanin resistance could not be explained by teicoplanin administration, since only four patients received teicoplanin. The evaluation of low-level teicoplanin resistance may improve the detection of GISA isolates. Further studies are warranted to evaluate the impact of low-level teicoplanin resistance on the outcome of glycopeptide therap

Quantum Scattering in Quasi-1D Cylindrical Confinement

Finite size effects alter not only the energy levels of small systems, but can also lead to new effective interactions within these systems. Here the problem of low energy quantum scattering by a spherically symmetric short range potential in the presence of a general cylindrical confinement is investigated. A Green's function formalism is developed which accounts for the full 3D nature of the scattering potential by incorporating all phase-shifts and their couplings. This quasi-1D geometry gives rise to scattering resonances and weakly localized states, whose binding energies and wavefunctions can be systematically calculated. Possible applications include e.g. impurity scattering in ballistic quasi-1D quantum wires in mesoscopic systems and in atomic matter wave guides. In the particular case of parabolic confinement, the present formalism can also be applied to pair collision processes such as two-body interactions. Weakly bound pairs and quasi-molecules induced by the confinement and having zero or higher orbital angular momentum can be predicted, such as p- and d-wave pairings.Comment: Extended version of quant-ph/050319

Husimi Maps in Lattices

We build upon previous work that used coherent states as a measurement of the local phase space and extended the flux operator by adapting the Husimi projection to produce a vector field called the Husimi map. In this article, we extend its definition from continuous systems to lattices. This requires making several adjustments to incorporate effects such as group velocity and multiple bands. Several phenomena which uniquely occur in lattice systems, like group-velocity warping and internal Bragg diffraction, are explained and demonstrated using Husimi maps. We also show that scattering points between bands and valleys can be identified in the divergence of the Husimi map

Mortality among young people seeking residential treatment for problematic drug and alcohol use: A data linkage study.

Background Young people with problematic alcohol and other drug (AOD) use are often referred to residential treatment. Subsequent mortality rates among this high-risk group is not known. This study estimates mortality rates and determines causes of death amongst young people referred to residential treatment in Sydney, Australia. Design Retrospective data linkage study. Data of young people (13–18 years) referred to a residential treatment service 2001–2015 (n = 3256) linked with Australian death registration data, and followed up to 16 years (2001–2016). Methods Mortality rates (CMRs) and standardised mortality ratios (SMRs, age-, gender-, calendar-year-adjusted) calculated using population mortality rates. Causes of death were analysed using ICD-10 codes for AOD-induced, AOD as contributory and non-AOD related causes. Results During follow-up of the cohort (28,838 person-years), 63 people died (71.4 % males; 48 % Indigenous; median age at death = 21.9 years; median follow-up = 5.1years), with 76 % dying before aged 25 years. Overall mortality (SMR = 4.91, 95 % CI: 3.8−6.2; CMR = 2.18/1000 person-years, 95 % CI: 1.7−2.8) was significantly higher than age-gender-matched general population, particularly in females (SMR = 9.55; males: SMR = 4.11; RR: 2.3, 95 % CI: 1.3–4.1). SMRs were not significantly different between treatment groups (SMRs>5.5) and non-attend group (SMR = 3.7) (p = 0.359). Two-thirds of deaths involved AOD, with AOD-induced deaths comprising 42 % and AOD as contributory for 22 % deaths. Overdose, mainly opioids (including opiates), suicide, and transport accidents were major causes of deaths. Conclusion Very high mortality rates, particularly among females, and the high incidence of overdose and suicide emphasise early screening for those at high-risk, targeted and culturally appropriate interventions, and maximised continuing after-care accessible to young people