22 research outputs found
Management of severe intraoperative hemorrhage during intraventricular neuroendoscopic procedures: the dry field technique
Objective Neuroendoscopic procedures inside the ventricular system always bear the risk for an unexpected intraoperative
hemorrhage with potentially devastating consequences. The authors present here their experience, and a stage-to-stage guide
for the endoscopic management of intraoperative hemorrhages.
Methods A step-by-step guide for the management to gain control of and stop the bleeding is described including a grading
system. More advanced techniques are presented in cases examples.
Conclusion Most of intraoperative hemorrhages can be controlled by constant irrigation and coagulation. More advanced
techniques can be applied quickly and easily to ensure control of the hemorrhages and avoid the need for a microsurgical
conversion
Organizational culture, leadership style and effectiveness: A case study of middle eastern construction clients
During the last few decades, organizational effectiveness has received a great deal of attention in many industrial sectors. As a result, a variety of models have been formulated which measure organizational performance. In the construction industry, two factors have subsequently captured the imagination and interest of researchers and practitioners alike: the culture of the organization and the leadership style of project managers. This focus places a requirement upon construction organizations to recognize and understand their organizational culture, and equally, to clearly communicate it to their employees as part of their capitalist drive of constantly improving performance, productivity and profit. Traditional ways of conducting construction business require a sound understanding of the technical and managerial demands of executing projects, which in turn, places an increased emphasis upon the management and leadership competencies of individual project managers. The purpose of the research is to explore the relationship between organizational culture, authentic leadership style and effectiveness within the context of a case study investigation centred on Middle Eastern construction clients and their project managers. The outcomes of the investigation, which include the presentation of an explanatory model, indicate that organizational culture is directly and positively related to performance and effectiveness, while project managers' leadership style has an indirect relationship to effectiveness. A strong organizational culture is therefore deemed critical to organizational performance
On the nucleation of ikaite (CaCO3x6H2O) â A comparative study in the presence and absence of mineral surfaces
The formation of ikaite (CaCO3x6H2O) was studied in the presence and absence of quartz and mica surfaces using desupersaturation curves from cryo-mixed-batch-reactor experiments. Upon nucleation and growth within the reactor, the solution approached solubility of the precipitating carbonate phase. For ikaite, a solubility constant of log Ksp ikaite = -7.3 ± 0.1 was found (T = 0 °C). At supersaturations Ωikaite < 15, the nucleation of ikaite was significantly promoted by the presence of quartz or mica. This promotion prevented a competing nucleation of anhydrous calcium carbonates. In the presence of quartz or mica, therefore, ikaite forms over a much broader supersaturation range than in the absence. Similarly strong promotors of ikaite nucleation rather than anhydrous carbonate nucleation were previously attributed to calcite-inhibiting substances only.
At supersaturations Ωikaite ℠8, application of classical nucleation theory on induction periods of ikaite formation yielded an effective interfacial energy of 15 ± 3 mJ/m2. Compared to data of anhydrous CaCO3 phases, this interfacial energy is low and expresses the highly hydrated character of ikaite. At supersaturations Ωikaite ℠18, a transient amorphous phase appeared besides ikaite.
Our results show that a comprehensive understanding of ikaite formation in natural settings requires consideration not only of supersaturation and presence of calcite-inhibitors but also of the presence or absence of mineral surfaces capable of promoting heterogeneous nucleation of ikaite
Neutral Atom Quantum Computing Hardware: Performance and End-User Perspective
We present an industrial end-user perspective on the current state of quantum
computing hardware for one specific technological approach, the neutral atom
platform. Our aim is to assist developers in understanding the impact of the
specific properties of these devices on the effectiveness of algorithm
execution. Based on discussions with different vendors and recent literature,
we discuss the performance data of the neutral atom platform. Specifically, we
focus on the physical qubit architecture, which affects state preparation,
qubit-to-qubit connectivity, gate fidelities, native gate instruction set, and
individual qubit stability. These factors determine both the quantum-part
execution time and the end-to-end wall clock time relevant for end-users, but
also the ability to perform fault-tolerant quantum computation in the future.
We end with an overview of which applications have been shown to be well suited
for the peculiar properties of neutral atom-based quantum computers
Co-exposure to urban particulate matter and aircraft noise adversely impacts the cerebro-pulmonary-cardiovascular axis in mice
Worldwide, up to 8.8 million excess deaths/year have been attributed to air pollution, mainly due to the exposure to fine particulate matter (PM). Traffic-related noise is an additional contributor to global mortality and morbidity. Both health risk factors substantially contribute to cardiovascular, metabolic and neuropsychiatric sequelae. Studies on the combined exposure are rare and urgently needed because of frequent co-occurrence of both risk factors in urban and industrial settings. To study the synergistic effects of PM and noise, we used an exposure system equipped with aerosol generator and loud-speakers, where C57BL/6 mice were acutely exposed for 3d to either ambient PM (NIST particles) and/or noise (aircraft landing and take-off events). The combination of both stressors caused endothelial dysfunction, increased blood pressure, oxidative stress and inflammation. An additive impairment of endothelial function was observed in isolated aortic rings and even more pronounced in cerebral and retinal arterioles. The increase in oxidative stress and inflammation markers together with RNA sequencing data indicate that noise particularly affects the brain and PM the lungs. The combination of both stressors has additive adverse effects on the cardiovascular system that are based on PM-induced systemic inflammation and noise-triggered stress hormone signaling. We demonstrate an additive upregulation of ACE-2 in the lung, suggesting that there may be an increased vulnerability to COVID-19 infection. The data warrant further mechanistic studies to characterize the propagation of primary target tissue damage (lung, brain) to remote organs such as aorta and heart by combined noise and PM exposure
Ultra-fast yttrium hydride chemistry at high pressures via non-equilibrium states induced by x-ray free electron laser
Controlling the formation and stoichiometric content of desired phases of
materials has become a central interest for the study of a variety of fields,
notably high temperature superconductivity under extreme pressures. The further
possibility of accessing metastable states by initiating reactions by x-ray
triggered mechanisms over ultra-short timescales is enabled with the
development of x-ray free electron lasers (XFEL). Utilizing the exceptionally
high brilliance x-ray pulses from the EuXFEL, we report the synthesis of a
previously unobserved yttrium hydride under high pressure, along with
non-stoichiometric changes in hydrogen content as probed at a repetition rate
of 4.5\,MHz using time-resolved x-ray diffraction. Exploiting non-equilibrium
pathways we synthesize and characterize a hydride with yttrium cations in an
\textit{A}15 structure type at 125\,GPa, predicted using crystal structure
searches, with a hydrogen content between 4.0--5.75 hydrogens per cation, that
is enthalpically metastable on the convex hull. We demonstrate a tailored
approach to changing hydrogen content using changes in x-ray fluence that is
not accessible using conventional synthesis methods, and reveals a new paradigm
in metastable chemical physics
Nanoelectronic COupled problems solutions - nanoCOPS: modelling, multirate, model order reduction, uncertainty quantification, fast fault simulation
The FP7 project nanoCOPS derives new methods for simulation during development of designs of integrated products. It covers advanced simulation techniques for electromagnetics with feedback couplings to electronic circuits, heat and stress. It is inspired by interest from semiconductor industry and by a simulation tool vendor in electronic design automation. The project is on-going and the paper presents the outcomes achieved after the first half of the project duration
Waveform relaxation for field/circuit coupled problems with cutsets of inductances and current sources
A Citizen Science Approach to Measuring Microplastics in Berlin's Water
Microplastic and nanoplastic pollution is a continuously growing threat to our environment. The goal of our project was to increase awareness of this risk in elementary students in the Treptow-Köpenick district of Berlin. Through our partnership with Leibniz-IGB and other district affiliates, we developed a lesson plan containing a student experiment, a presentation, infographics, and reflection materials to teach students about the problem. Increasing awareness in younger generations is an important step in hopes of attaining a more sustainable future
Accelerated lifetime testing of thinâfilm solar cells at high irradiances and controlled temperatures
Within this study, we investigate the intrinsic photostability of thin-film solar cells,here organic photovoltaic cells. Since degradation under natural sun light proceedswithin the timeframe of months and years, the process needs to be speeded up forfast material analysis and screening, using high-concentration accelerated lifetimetesting (high-C ALT). For this purpose, we established setups allowing irradiances ofup to 730 sun equivalents (SE). One key finding of our study is that accelerating thetesting procedure by such large intensities is possible but a precise measurement andcontrol of the solar cell temperature is absolutely essential. Accordingly, we devel-oped an innovative method of determining the temperature of the active layer whichoffers significant advantages over commonly used measurement methods. Further-more, it was found that the degradation process under high illumination densities canbe well described by a stretched exponential law. We demonstrate that the tempera-ture kinetics of P3HT:PCBM was found to be Arrhenius governed with an activationenergy of 27.2 kJ/mol under continuous illumination of 300 SE. Finally, it was shownthat the velocity of light-induced degradation of short-circuit current depends line-arly on the used irradiance dose at a given temperature starting from normal illumina-tion conditions up to at least 300 SE. This makes high-C ALT a very valuable tool forswift screening of the lifetime of novel thin-film solar cells and materials