11,396 research outputs found
Outcomes of Robot-Assisted Pancreaticoduodenectomy in Patients Older Than 70 Years: A Comparative Study
No full textBackground Minimally invasive pancreaticoduodenectomy (PD) remains one of the most challenging abdominal procedures and its application in the elderly population is poorly reported in the literature so far. The goal of this study was to demonstrate that robot-assisted PD can be safely performed in patients aged 70 years and older. Methods Forty-one consecutive robot-assisted PD performed between April 2007 and January 2010 were prospectively entered in a dedicated database. Patients were stratified into two groups: group 1, aged C70 years (n = 15, 36.6%); and group 2, aged<70 years (n = 26, 63.4%). The data were reviewed retrospectively. Results Indications for surgery and patient characteristics were the same in both groups, with the exception of age. There was no statistical difference in terms of operative time (P = 0.376), blood loss (P = 0.989), conversion rate (P = 0.52), mortality (P = 0.36), or overall morbidity rate (P = 0.74). The mean hospital stay was 14.3 days in group 1 and 11.2 days in group 2. This was not statistically significant (P = 0.136). Conclusions Robot-assisted pancreaticoduodenectomy can be performed safely in elderly patients with comparable mortality, morbidity, and outcomes compared with a younger population. Age alone should not be a contraindication for robotic pancreatic resectio
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Ultra-thin electron collectors based on nc-Si:H for high-efficiency silicon heterojunction solar cells
No full textLow parasitic absorption and high conductivity enable (n)-type hydrogenated nanocrystalline silicon [(n)nc-Si:H], eventually alloyed with oxygen [(n)nc-SiOx:H], to be deployed as window layer in high-efficiency silicon heterojunction (SHJ) solar cells. Besides the appropriate opto-electrical properties of these nanocrystalline films, reduction of their thickness is sought for minimizing parasitic absorption losses. Many strategies proposed so far reveal practical limits of the minimum (n)-layer thickness that we address and overcome in this manuscript. We demonstrated the successful application of an ultra-thin layer of only 3-nm-thick based on (n)nc-Si:H PECVD plasma growth conditions without the use of additional contact or buffer layers. For simplicity, we still name (n)nc-Si:H this ultra-thin layer and the solar cell endowed with it delivers a certified efficiency η of 22.20%. This cell shows a 0.61 mA/cm2 overall JSC gain over the (n)a-Si:H counterpart mainly owing to the higher transparency of (n)nc-Si:H, while maintaining comparable VOC > 714 mV and FF > 80%. Our optimized (n)nc-Si:H layer yields low absorption losses that are commonly measured for (n)nc-SiOx:H films. In this way, we are able to avoid the detrimental effect that oxygen incorporation has on the electrical parameters of these functional layers. Further, by applying a MgF2/ITO double-layer anti-reflection coating, a cell with 3-nm-thick (n)nc-Si:H exhibits a JSC,EQE up to 40.0 mA/cm2. By means of EDX elemental mapping, we additionally identified the (n)nc-Si:H/ITO interface as critical for electron transport due to unexpected oxidation. To avoid this interfacial oxidation, insertion of a 2-nm-thick (n)a-Si:H on the 3-nm-thick (n)nc-Si:H contributes to FF gains of 1.4%abs. (FF increased from 78.6% to 80.0%), and showing further room for improvements.Photovoltaic Materials and DevicesQN/AfdelingsbureauElectrical Sustainable Energ
Texturing approaches for the fabrication of nc-Si:H/c-Si tandem devices
No full textThis thesis is dedicated to the fabrication of a novel silicon based tandem cell which combines hydrogenated nanocrystalline silicon (nc-Si:H) thin film(TF) photovoltaic (PV) technology and silicon heterojunction (SHJ) c-Si based PV technology. As a matter of fact, the growth of nc-Si:H on a flat c-Si substrate is not uniformas it irregularly peels off after deposition using the plasma enhanced chemical vapor deposition (PECVD). On the other hand, the growth of the nc-Si:H TF layers on the standard alkaline textured c-Si substrate with sharp pyramidal structures results in defective regions in the bulk of nc-Si:H grown material. A nc-Si:H layer with high defect density reduces the voltage and the fill factor (FF) of the tandem device. In order to minimize the defect density in the nc-Si:H absorber layer, different texturing approaches (TA) were developed for the c-Siwafer to facilitate better growth of the nc-Si:H absorber. The surface morphology of the textured c-Si wafers for all TA’s at different etching time steps were investigated. Prior to TF layer deposition for the SHJ and the tandem devices, various cleaning approaches were investigated to improve the surface passivation of the textured c-Si wafers. The investigation of the grown nc-Si:H layer using different TA’s showed that smoothening of the sharp pyramidal structures significantly improved the nc-Si:H grown bulk as it helped in better growth of nc-Si:H with no significant defects. Finally, the current density-voltage (J-V) measurements were investigated for all TA’s for the SHJ and the tandem devices. The best performing tandem cell has an open circuit voltage (Voc ) of 1.02 V , short current density (Jsc ) of 13.34 mA/cm-2 and a FF of 0.44. It is expected that optimizing the tunnel recombination junction (TRJ) will further improve the electrical performance of the tandem devices for all TA’s.Electrical Engineering | Sustainable Energy Technolog
An approach to nano-chemical analysis through NC-AFM technique
No full textWe have measured the NC-AFM frequency shift dependence on the X-ray energy around the Au L3 absorption edge energy. We found a peak in the frequency shift just above the Au region at the Au L3 absorption edge energy while we could not detect any peak in the frequency shift when the NC-AFM tip was placed above the Si regions. This novel phenomenon indicated that the combination of energy-variable X-rays and NC-AFM provides us a new way to nano level chemical mapping at surface. We briefly discussed some possible mechanisms
A phased city energy platform for networked precinct buildings in the context of management information systems and smart grids
No full textThis research investigates the context and advantages of energy sharing between networked precinct buildings in the context of pre-existing urban stock. The paper considers whether the sharing of patterns of use and knowledge of buildings’ spatial, architectural and energyrelated components can act as a phased prequel to energy sharing and provide a ‘knowledge pool’ to facilitate changes to the technological mix in a building, as well as modes of usage. In the context of energy use and conservation it is well understood that resource sharing can be advantageous across multiple buildings, but less is known about the potential benefits of energy knowledge sharing across buildings. The sharing of energy data across buildings with different owners/operators but offers the advantages of balancing demand across facilities, right-sizing technology components, intelligent planning and future usage pooling – particularly for smart buildings with energy storage and generation capacity. With a focus on the Australian context, this research investigation examines how an initial energy information platform phase could benefit a range of building stakeholders and be lead to a subsequent energy sharing phase. The author argues that there is value in a city energy information platform as a prequel to smart grids and subsequently as a complement to smart grids
Investigation of silicon NC memory with improved threshold voltage window
No full textMemory capacitors with the structure of thin tunneling oxide layer/silicon nanocrystal (NC) layer/thick controlling oxide layer were fabricated by both LPCVD method and low energy ion implantation method. The silicon NC formation condition, its size and density which have great influence on silicon NC memory characteristics are experimentally investigated in this paper. Silicon NC memory with a 2V threshold voltage window was obtained by optimized silicon ion implantation technology, which is beneficial to the practical application of the silicon NC memory device.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000259893500133&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, Electrical & ElectronicNanoscience & NanotechnologyEICPCI-S(ISTP)
Analysis of Chemical Warfare Agents at the NC Laboratory Spiez
No full textThe group for chemical analysis and verification at the NC Laboratory Spiez engages in the analysis of chemical warfare agents and related compounds in the frame of international chemical disarmament. Its area of work and instrumentation are described together with the analysis of a
sample taken in Iraq after the Gulf War
Conservation genetics of Pristis sawfishes in Australian waters
No full textNorthern Australia is believed to contain the last ‘viable’ populations of the critically endangered Freshwater Sawfish, Pristis microdon, Dwarf Sawfish, Pristis clavata, and Green Sawfish, Pristis zijsron, making these populations of global significance. Mitochondrial and microsatellite markers were used to investigate the population structure, levels of genetic diversity, and evolutionary history of each of these species in northern Australian waters. Pristis microdon, which utilizes freshwater rivers as juveniles and marine waters as adults, has high levels of mtDNA heterogeneity and no nDNA heterogeneity; indicating that this species has female philopatry coupled with male-biased dispersal in northern Australian waters. The conservation plans for this species should, therefore, place a high priority on the protection of females, pupping grounds, and nursery areas to minimize the risk of extirpation. Conservation plans also need to consider the likelihood that a decline in the abundance of this species in one location could have an effect on its abundance and genetic ‘health’ in other locations via male gene flow. In contrast, P. clavata and P. zijsron, which spend their entire lives in marine and/or estuarine waters, each have heterogeneity in the mtDNA and nDNA markers, suggesting that gene flow in both males and females is restricted at large spatial scales in northern Australian waters. Consequently, the risk of extirpation for each of these species is relatively high since a decline in abundance is unlikely to be replenished by immigration from other locations. Therefore, conservation plans for P. clavata and P. zijsron should place a high priority on the protection of males and females, as well as pupping grounds and nursery areas. Most of the assemblages of each of the Pristis species contained moderate and high levels of diversity in mtDNA and nDNA markers, respectively. This suggests that the prognosis for the short and medium-term survival of each of these species in Australian waters is relatively good, providing that measures are put in place to curb any further declines in abundance. However, the levels of mtDNA diversity in the assemblage of each of P. clavata and P. zijsron in the Gulf of Carpentaria were reduced and, therefore, these assemblages may warrant special conservation status. Finally, the evolutionary histories of the Pristis species in Australian waters have most likely played an important role in shaping the observed patterns of population structure and levels of genetic diversity, however, the relative influence of contemporary versus historic factors on the amount and distribution of genetic variation in each of these species remains somewhat unresolved
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