Metal–semiconductor–metal photodetector on as-deposited TiO2 thin films on sapphire substrate

Cataloged from PDF version of article.TiO2 thin films are prepared on c-plane sapphire substrates by the RF magnetron sputtering method. The performance of the Pt contact metal–semiconductor–metal (MSM) photodetector fabricated on as-deposited films is studied. The dark current density and the responsivity obtained were 1.57 × 10−9 A/cm2 at 5 V bias and 1.73 A/W at 50 V bias, respectively. Breakdown is not observed up to 50 V bias. Rise and fall times for the photocurrent were 7 and 3 s, respectively. Our results show that high quality MSM photodetectors can be fabricated without high temperature and complicated fabrication steps

Low dark current and high speed ZnO metal–semiconductor–metal photodetector on SiO2/Si substrate

Cataloged from PDF version of article.ZnO thin films are deposited by radio-frequency magnetron sputtering on thermally grown SiO2 on Si substrates. Pt/Au contacts are fabricated by standard photolithography and lift-off in order to form a metal-semiconductor-metal (MSM) photodetector. The dark current of the photodetector is measured as 1 pA at 100V bias, corresponding to 100 pA/cm(2) current density. Spectral photoresponse measurement showed the usual spectral behavior and 0.35 A/W responsivity at a 100V bias. The rise and fall times for the photocurrent are measured as 22 ps and 8 ns, respectively, which are the lowest values to date. Scanning electron microscope image shows high aspect ratio and dense grains indicating high surface area. Low dark current density and high speed response are attributed to high number of recombination centers due to film morphology, deducing from photoluminescence measurements. These results show that as deposited ZnO thin film MSM photodetectors can be used for the applications needed for low light level detection and fast operation. (C) 2014 AIP Publishing LLC

Intra-arterial thrombolysis of occluded middle cerebral artery by use of collateral pathways in patients with tandem cervical carotid artery/middle cerebral artery occlusion

BACKGROUND AND PURPOSE: Cervical internal carotid artery (ICA) occlusion with middle cerebral artery (MCA) embolic occlusion is associated with a low rate of recanalization and poor outcome after intravenous thrombolysis. Prompt revascularization is required to prevent disabling stroke. We report our experience on acute ischemic stroke patients with tandem ICA or MCA occlusions treated with microcathether navigation and intra-arterial thrombolysis by use of collateral pathways including the posterior or anterior communicating arteries, or both pathways. MATERIALS AND METHODS: We retrospectively identified 8 patients with proximal ICA occlusion associated with MCA embolic occlusions treated with intra-arterial thrombolysis (IA rtPA). Access to the occluded MCA was obtained via catheter navigation through intact collateral pathways, including posterior communicating (PcomA) or anterior communicating (AcomA) arteries, without passing a microcathether through the acutely occluded ICA. We assessed clinical outcomes using modified Rankin scale (mRS) and National Institutes of Health Stroke Scale (NIHSS). RESULTS: Eight patients with a mean age of 57 ± 4 years and median NIHSS of 14 were identified. Mean time from stroke onset to intra-arterial thrombolysis was 292 ± 44 minutes. The MCA was revascularized completely in 5 of the 8 patients via collateral intra-arterial rtPA administration. All of the patients had a favorable outcome defined as a mRS of ≤2 or more at 1 and 3 months\u27 follow-up after thrombolytic therapy. One patient had an asymptomatic petechial hemorrhage. CONCLUSION: In this small number of patients with tandem occlusions of the ICA and MCA, intraarterial thrombolysis and recanalization of the MCA by use of collateral pathways to bypass the occluded ICA is a safe and efficacious therapeutic option

Lensless high-resolution on-chip optofluidic microscopes for Caenorhabditis elegans and cell imaging

Low-cost and high-resolution on-chip microscopes are vital for reducing cost and improving efficiency for modern biomedicine and bioscience. Despite the needs, the conventional microscope design has proven difficult to miniaturize. Here, we report the implementation and application of two high-resolution (≈0.9 μm for the first and ≈0.8 μm for the second), lensless, and fully on-chip microscopes based on the optofluidic microscopy (OFM) method. These systems abandon the conventional microscope design, which requires expensive lenses and large space to magnify images, and instead utilizes microfluidic flow to deliver specimens across array(s) of micrometer-size apertures defined on a metal-coated CMOS sensor to generate direct projection images. The first system utilizes a gravity-driven microfluidic flow for sample scanning and is suited for imaging elongate objects, such as Caenorhabditis elegans; and the second system employs an electrokinetic drive for flow control and is suited for imaging cells and other spherical/ellipsoidal objects. As a demonstration of the OFM for bioscience research, we show that the prototypes can be used to perform automated phenotype characterization of different Caenorhabditis elegans mutant strains, and to image spores and single cellular entities. The optofluidic microscope design, readily fabricable with existing semiconductor and microfluidic technologies, offers low-cost and highly compact imaging solutions. More functionalities, such as on-chip phase and fluorescence imaging, can also be readily adapted into OFM systems. We anticipate that the OFM can significantly address a range of biomedical and bioscience needs, and engender new microscope applications

Designing research tools : empirical knowledge as a base for future beekeeping.

The world-wide phenomenon of the disappearance of bees with the consequential imbalance of ecosystems is a problem that needs to be addressed in order to guarantee a sustainable future. Beekeeping is an activity, generally associated to agriculture, that allows small farmers to generate more food and income, this reality has had a shift in recent years with the number of small beekeepers decreasing, and big corporations gaining control over the industry. Regulations and the Colony Collapse Disorder, among other factors, may have a major role in these phenomena. With the intent to contribute to a more sustainable beekeeping practice, this research is being conducted to better understand this reality, looking for design driven opportunities. The challenge is to gain a deeper understanding of the beekeepers, a practice that is understudied by designers, particularly considering in-depth research methods. This paper discusses an experimental design study in the Turkish Aegean region that was conducted with local beekeepers to better understand the existing specifications: by discussing their business models, in order to understand and analyze socio-cultural factors that contributed to the existing system, and propose changes for a more sustainable practice. As a starting point for a first phase survey, the intent is to generate original data which will serve as the foundation for future works. Beekeepers in this scenario are mainly senior male farmers that belong to a low literacy audience, who learned the practice from their predecessors. In order to identify the problems of beekeepers, we needed to design and adjust our research methods according to the specifications of the audience. For this reason, a three stage inquiry was designed to better communication in order to extract measurable data from their empirical knowledge through a series of workshops. The case study reports the workshop sessions for identifying the design strategies with a focus on voicing the beekeepers problems. The first level draws upon explicit knowledge to identify the audience. For the second level an illustrated questionnaire was designed to visually represent the quantitative data about the business. The process is exercised with a new design because the content of knowledge is tacit and personal. Finally, the third level is an interview session to validate the data gathered from the previous stages. This paper will present the findings of the workshops with the aim to formulate an appropriate way to employ new approaches to exploring and defining design problems with visual representations. We also seek to extend our research in other contexts that will help discuss the role of design as a tool for developing new methodologies of design research. As a consequence we will propose prototypes of artifacts that will consider the implementation into beekeeping of new biomaterials, technology, branding and commercialization planning, etc., that may help create a more sustainable beekeeping practice. Beekeepers will be invited to analyze proposals and give their contributions. This process will render into redesigned optimized artifacts that will merge empirical knowledge with the needs of sustainable beekeeping. Keywords design research tools, beekeeping, sustainability, eco-innovation, cooperatio

On transformation of query scheduling strategies in distributed and heterogeneous database systems

This work considers a problem of optimal query processing in heterogeneous and distributed database systems. A global query sub- mitted at a local site is decomposed into a number of queries processed at the remote sites. The partial results returned by the queries are in- tegrated at a local site. The paper addresses a problem of an optimal scheduling of queries that minimizes time spend on data integration of the partial results into the final answer. A global data model defined in this work provides a unified view of the heterogeneous data structures located at the remote sites and a system of operations is defined to ex- press the complex data integration procedures. This work shows that the transformations of an entirely simultaneous query processing strate- gies into a hybrid (simultaneous/sequential) strategy may in some cases lead to significantly faster data integration. We show how to detect such cases, what conditions must be satisfied to transform the schedules, and how to transform the schedules into the more efficient ones

A randomised controlled trial of the Neuro Emotional Technique (NET) for childhood Attention Deficit Hyperactivity Disorder (ADHD): a protocol

<p>Abstract</p> <p>Background</p> <p>An abundance of literature is dedicated to research for the treatment of Attention Deficit Hyperactivity Disorder (ADHD). Most, is in the area of pharmacological therapies with less emphasis in psychotherapy and psychosocial interventions and even less in the area of complementary and alternative medicine (CAM).</p> <p>The use of CAM has increased over the years, especially for developmental and behavioral disorders, such as ADHD. 60–65% of parents with children with ADHD have used CAM. Medical evidence supports a multidisciplinary approach (i.e. pharmacological and psychosocial) for the best clinical outcomes. The Neuro Emotional Technique (NET), a branch of Chiropractic, was designed to address the biopsychosocial aspects of acute and chronic conditions including non-musculoskeletal conditions. Anecdotally, it has been suggested that ADHD may be managed effectively by NET.</p> <p>Design/methods</p> <p>A placebo controlled, double blind randomised clinical trial was designed to assess the effectiveness of NET on a cohort of children with medically diagnosed ADHD.</p> <p>Children aged 5–12 years who met the inclusion criteria were randomised to one of three groups. The control group continued on their existing medical regimen and the intervention and placebo groups had the addition of the NET and sham NET protocols added to their regimen respectively. These two groups attended a clinical facility twice a week for the first month and then once a month for six months.</p> <p>The Conners' Parent and Teacher Rating Scales (CRS) were used at the start of the study to establish baseline data and then in one month and in seven months time, at the conclusion of the study. The primary outcome measures chosen were the Conners' ADHD Index and Conners' Global Index. The secondary outcome measures chosen were the DSM-IV: Inattentive, the DSM-IV:Hyperactive-Impulsive, and the DSM-IV:Total subscales from the Conners' Rating Scales, monitoring changes in inattention, hyperactivity and impulsivity.</p> <p>Calculations for the sample size were set with a significance level of 0.05 and the power of 80%, yielding a sample size of 93.</p> <p>Discussion</p> <p>The present study should provide information as to whether the addition of NET to an existing medical regimen can improve outcomes for children with ADHD.</p> <p>Trial registration</p> <p>Australian New Zealand Clinical Trial Registration Number: ANZCTRN 012606000332527</p