Point defects in silicon after zinc diffusion - a deep level transient spectroscopy and spreading-resistance profiling study

We present results from spreading-resistance profiling and deep level transient spectroscopy on Si after Zn diffusion at 1294 K. Concentration profiles of substitutional in dislocation-free and highly dislocated Si are described by a diffusion mechanism involving interstitial-substitutional exchange. Additional annealing at 873 K following quenching from the diffusion temperature is required in the case of dislocation-free Si to electrically activate . The formation of complexes of with unwanted impurities upon quenching is discussed. Additional Ni diffusion experiments as well as total energy calculations suggest that Ni is a likely candidate for the passivation of Zns. From total energy calculations we find that the formation of complexes involving Zn and Ni depends on the position of the Fermi level. This explains differences in results from spreading-resistance profiling and deep level transient spectroscopy on near-intrinsic and p-type Si, respectively

A Hedonism Hub in the Human Brain

Human values are abstract ideals that motivate behavior. The motivational nature of human values raises the possibility that they might be underpinned by brain structures that are particularly involved in motivated behavior and reward processing. We hypothesized that variation in subcortical hubs of the reward system and their main connecting pathway, the superolateral medial forebrain bundle (slMFB) is associated with individual value orientation. We conducted Pearson's correlation between the scores of 10 human values and the volumes of 14 subcortical structures and microstructural properties of the medial forebrain bundle in a sample of 87 participants, correcting for multiple comparisons (i.e.,190). We found a positive association between the value that people attach to hedonism and the volume of the left globus pallidus (GP).We then tested whether microstructural parameters (i.e., fractional anisotropy and myelin volume fraction) of the slMFB, which connects with the GP, are also associated to hedonism and found a significant, albeit in an uncorrected level, positive association between the myelin volume fraction within the left slMFB and hedonism scores. This is the first study to elucidate the relationship between the importance people attach to the human value of hedonism and structural variation in reward-related subcortical brain regions

Profiling soil microbial communities influenced by reduced summer precipitation and farming system history

Soil bacteria and fungi are the basis of soil food webs and contribute to a wide range of essential soil functions in arable lands. Intense land use and climate change induced reductions in summer precipitation can have varying influences on abundance, composition, and activity of microbial communities with largely unknown consequences for soil functions and plant growth including crop yields. The impact of altered precipitation patterns on soil biodiversity and associated ecosystem functions is on top of the list of eight major research gaps identified by an expert group for the European Commission still, this relationship is rarely studied under field conditions

An all silicon quantum computer

A solid-state implementation of a quantum computer composed entirely of silicon is proposed. Qubits are Si-29 nuclear spins arranged as chains in a Si-28 (spin-0) matrix with Larmor frequencies separated by a large magnetic field gradient. No impurity dopants or electrical contacts are needed. Initialization is accomplished by optical pumping, algorithmic cooling, and pseudo-pure state techniques. Magnetic resonance force microscopy is used for readout. This proposal takes advantage of many of the successful aspects of solution NMR quantum computation, including ensemble measurement, RF control, and long decoherence times, but it allows for more qubits and improved initialization.Comment: ReVTeX 4, 5 pages, 2 figure

The UN in the lab

We consider two alternatives to inaction for governments combating terrorism, which we term Defense and Prevention. Defense consists of investing in resources that reduce the impact of an attack, and generates a negative externality to other governments, making their countries a more attractive objective for terrorists. In contrast, Prevention, which consists of investing in resources that reduce the ability of the terrorist organization to mount an attack, creates a positive externality by reducing the overall threat of terrorism for all. This interaction is captured using a simple 3×3 “Nested Prisoner’s Dilemma” game, with a single Nash equilibrium where both countries choose Defense. Due to the structure of this interaction, countries can benefit from coordination of policy choices, and international institutions (such as the UN) can be utilized to facilitate coordination by implementing agreements to share the burden of Prevention. We introduce an institution that implements a burden-sharing policy for Prevention, and investigate experimentally whether subjects coordinate on a cooperative strategy more frequently under different levels of cost sharing. In all treatments, burden sharing leaves the Prisoner’s Dilemma structure and Nash equilibrium of the game unchanged. We compare three levels of burden sharing to a baseline in a between-subjects design, and find that burden sharing generates a non-linear effect on the choice of the efficient Prevention strategy and overall performance. Only an institution supporting a high level of mandatory burden sharing generates a significant improvement in the use of the Prevention strategy

Tension band wiring for simple olecranon fractures: evaluation of surgical technique

Abstract Background In some settings, specific techniques for open reduction and internal fixation are preferred based on the eminence of a surgeon or professional organization. An emphasis on technical aspects of surgery that are not proved superior and vary substantially from surgeon to surgeon can be confusing for trainees. This study applied a numerical grading of the technical aspects of tension band wire (TBW) fixation for olecranon fracture; assessed the interobserver agreement of each criterion; and measured the correlation of the technical grading and objective and subjective long-term outcomes. Materials and methods Forty observers were invited to rate the technical aspects of TBW fixation of the olecranon on 26 post-operative radiographs. The interobserver reliability of the rating was measured using the intra-class correlation coefficient. The correlation between the rating and motion, Mayo elbow performance index, and disabilities of the arm, shoulder and hand score was tested with the Spearman’s rank correlation test. Results None of the figure-of-eight TBW constructs were considered perfect according to the numerical grading: the majority of observers found three deviations per fixation. The interobserver agreement was only fair for the total number of deviations and no correlation between the number of deviations and long-term objective and subjective outcome was found. Conclusions A rating of the technical aspects of TBW for olecranon fractures was unreliable and did not correlate with subjective and objective outcomes. Emphasis on specific technical aspects of fixation might be confusing for trainees and could distract them from the principles of effective treatment. Level of evidence Level IV diagnostic study

Towards the fabrication of phosphorus qubits for a silicon quantum computer

The quest to build a quantum computer has been inspired by the recognition of the formidable computational power such a device could offer. In particular silicon-based proposals, using the nuclear or electron spin of dopants as qubits, are attractive due to the long spin relaxation times involved, their scalability, and the ease of integration with existing silicon technology. Fabrication of such devices however requires atomic scale manipulation - an immense technological challenge. We demonstrate that it is possible to fabricate an atomically-precise linear array of single phosphorus bearing molecules on a silicon surface with the required dimensions for the fabrication of a silicon-based quantum computer. We also discuss strategies for the encapsulation of these phosphorus atoms by subsequent silicon crystal growth.Comment: To Appear in Phys. Rev. B Rapid Comm. 5 pages, 5 color figure

Investigating the Sustainability of Outcomes in a Chronic Disease Treatment Programme

This study examines trends in chronic disease outcomes from initiation of a specialised chronic disease treatment programme through to incorporation of programme activities into routine service delivery. We reviewed clinical records of 98 participants with confirmed renal disease or hypertension in a remote indigenous community health centre in Northern Australia. For each participant the review period spanned an initial three years while participating in a specialised cardiovascular and renal disease treatment programme and a subsequent three years following withdrawal of the treatment programme. Responsibility for care was incorporated into the comprehensive primary care service which had been recently redeveloped to implement best practice care plans. The time series analysis included at least six measures prior to handover of the specialised programme and six following handover. Main outcome measures were trends in blood pressure (BP) control, and systolic and diastolic BP. We found an improvement in BP control in the first 6-12 months of the programme, followed by a steady declining trend. There was no significant difference in this trend between the pre- compared to the post-programme withdrawal period. This finding was consistent for control at levels below 130/80 and 140/90, and for trends in mean systolic and diastolic BP. Investigation of the sustainability of programme outcomes presents major challenges for research design. Sustained success in the management of chronic disease through primary care services requires better understanding of the causal mechanisms related to clinical intervention, the basis upon which they can be 'institutionalised' in a given context, and the extent to which they require regular revitalisation to maintain their effect