Dimension- and shape-dependent thermal transport in nano-patterned thin films investigated by scanning thermal microscopy

Scanning thermal microscopy (SThM) is a technique which is often used for the measurement of the thermal conductivity of materials at the nanometre scale. The impact of nano-scale feature size and shape on apparent thermal conductivity, as measured using SThM, has been investigated. To achieve this, our recently developed topography-free samples with 200 and 400 nm wide gold wires (50 nm thick) of length of 400–2500 nm were fabricated and their thermal resistance measured and analysed. This data was used in the development and validation of a rigorous but simple heat transfer model that describes a nanoscopic contact to an object with finite shape and size. This model, in combination with a recently proposed thermal resistance network, was then used to calculate the SThM probe signal obtained by measuring these features. These calculated values closely matched the experimental results obtained from the topography-free sample. By using the model to analyse the dimensional dependence of thermal resistance, we demonstrate that feature size and shape has a significant impact on measured thermal properties that can result in a misinterpretation of material thermal conductivity. In the case of a gold nanowire embedded within a silicon nitride matrix it is found that the apparent thermal conductivity of the wire appears to be depressed by a factor of twenty from the true value. These results clearly demonstrate the importance of knowing both probe-sample thermal interactions and feature dimensions as well as shape when using SThM to quantify material thermal properties. Finally, the new model is used to identify the heat flux sensitivity, as well as the effective contact size of the conventional SThM system used in this study

Alignment verification for electron beam lithography

Alignment between lithography layers is essential for device fabrication. A minor defect in a single marker can lead to incorrect alignment and this can be the source of wafer reworks. In this paper we show that this can be prevented by using extra alignment markers to check the alignment during patterning, rather than inspecting vernier patterns after the exposure is completed. Accurate vernier patterns can often only be read after pattern transfer has been carried out. We also show that by using a Penrose tile as a marker it is possible to locate the marker to about 1 nm without fully exposing the resist. This means that the marker can be reused with full accuracy, thus improving the layer to layer alignment accuracy. Lithography tool noise limits the process

Variance of transmitted power in multichannel dissipative ergodic structures invariant under time reversal

We use random matrix theory (RMT) to study the first two moments of the wave power transmitted in time reversal invariant systems having ergodic motion. Dissipation is modeled by a number of loss channels of variable coupling strength. To make a connection with ultrasonic experiments on ergodic elastodynamic billiards, the channels injecting and collecting the waves are assumed to be negligibly coupled to the medium, and to contribute essentially no dissipation. Within the RMT model we calculate the quantities of interest exactly, employing the supersymmetry technique. This approach is found to be more accurate than another method based on simplifying naive assumptions for the statistics of the eigenfrequencies and the eigenfunctions. The results of the supersymmetric method are confirmed by Monte Carlo numerical simulation and are used to reveal a possible source of the disagreement between the predictions of the naive theory and ultrasonic measurements.Comment: 10 pages, 2 figure

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target

Implementing the Five-A Model of technical refinement: Key roles of the sport psychologist

There is increasing evidence for the significant contribution provided by sport psychologists within applied coaching environments. However, this rarely considers their skills/knowledge being applied when refining athletes’ already learned and well-established motor skills. Therefore, this paper focuses on how a sport psychologist might assist a coach and athlete to implement long-term permanent and pressure proof refinements. It highlights key contributions at each stage of the Five-A Model—designed to deliver these important outcomes—providing both psychomotor and psychosocial input to the support delivery. By employing these recommendations, sport psychologists can make multiple positive contributions to completion of this challenging task

Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change

Topography-free sample for thermal spatial response measurement of scanning thermal microscopy

A novel fabrication technique is described for the production of multimaterial, lithographically defined, topography-free samples for use in experiments to investigate the nature of contrast in scanning probe microscopy (SPM). The approach uses a flat sacrificial substrate as the base for fabrication, which is deleted in the final step. This leaves an exposed, flat surface with patterns of materials contrast defined during the lithography stages. In the example application presented, these are designed to challenge the detection ability of a scanning thermal microscopy (SThM) probe, although many other applications can be envisioned. There are many instances in SPM where images can exhibit topographically induced artifacts. In SThM, these can result in a change of the thermal signal which can easily be misinterpreted as changes in the sample thermal conductivity or temperature. The elimination of these artifacts through postprocessing requires a knowledge of how the probe responds thermal features of differing sizes. The complete sample fabrication process, followed by successful topographic/thermal scanning is demonstrated, showing sub-1.5 nm topography with a clear artifact-free thermal signal from sub-100 nm gold wires. The thermal spatial resolution is determined for the sample materials and probe used in this study to be in the range of 35–75 nm

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics

Thermal induced deflection in atomic force microscopy cantilevers: analysis and solution

Atomic force microscopy (AFM) cantilevers are commonly made from two material layers: a reflective coating and structural substrate. Although effective, this can result in thermally induced cantilever deflection due to ambient and local temperature changes. While this has been previously documented, key aspects of this common phenomenon have been overlooked. This work explores the impact of thermally induced cantilever deflection when in- and out-of-contact, including the topographic scan artefacts produced. Scanning thermal microscopy probes were employed to provide direct cantilever temperature measurement from Peltier and microheater sources, whilst permitting cantilever deflection to be simultaneously monitored. Optical lever-based measurements of thermal deflection in the AFM were found to vary by up to 250% depending on the reflected laser spot location on the cantilever. This highlights AFM's inherent inability to correctly measure and account for thermal induced cantilever deflection in its feedback system. This is particularly problematic when scanning a tip in-contact with the surface, when probe behaviour is closer mechanically to that of a bridge than a cantilever regarding thermal bending. In this case, measurements of cantilever deflection and inferred surface topography contained significant artefacts and varied from negative to positive for different optical lever laser locations on the cantilevers. These topographic errors were measured to be up to 600 nm for a small temperature change of 2 K. However, all cantilevers measured showed a point of consistent, complete thermal deflection insensitivity 55% to 60% along their lengths. Positioning the reflected laser at this location, AFM scans exhibited improvements of up-to 97% in thermal topographic artefacts relative to other laser positions

An integrated approach to emergency triage assessment and treatment in Uganda

Background: Reducing mortality among patients who present to primary referral facilities in need of emergency care requires efficient triage and immediate correct management known more commonly as Emergency Triage, Assessment and Treatment (ETAT). Integrated Management of Infectious Disease (IMID) training and on-site support (OSS) have been the tools used to build capacity among mid-level practitioners who have been found to be lacking in ETAT skills in the region.Objective: To investigate the use of Integrated Management of Infectious Disease (IMID) training and on-site support (OSS) tools to improve ETAT in health care facilities in rural Uganda.Design: Randomized mixed methods evaluation.Setting: Thirty-six facilities in Uganda were randomized 1:1 to arm A (IMID and OSS) and arm B (IMID alone).Subjects: Two mid-level practitioners, (clinical officers or senior nurses), from each facility participated in offsite IMID training. Staff at 18 facilities in arm A participated in OSS (two days each month of outreach and quality improvement for nine months).Results: Time series data on facility performance of three ETAT indicators were compared over 14 months and data on mortality among pediatric inpatients were compared across arms. Improvements differed across facilities and indicators, but steady improvement in triage occurred in arm A, with convergence across arms in the management of emergency patients. Analysis of baseline indicators and improvements demonstrated that facilities could improve their performance regardless of their starting point.Conclusion: IMID and OSS both improved the management of patients with an acute illness presenting to rural health facilities