115 research outputs found
Oral coenzyme Q10 supplementation does not prevent cardiac alterations during a high altitude trek to Everest base camp
No full textAbstract Holloway, Cameron J., Andrew J. Murray, Kay Mitchell, Daniel S. Martin, Andrew W. Johnson, Lowri E. Cochlin, Ion Codreanu, Sundeep Dhillon, George W. Rodway, Tom Ashmore, Denny Z.H. Levett, Stefan Neubauer, Hugh E. Montgomery, Michael P.W. Grocott, and Kieran Clarke, on behalf of the Caudwell Xtreme Everest 2009 Investigators. Oral Coenzyme Q supplementation does not prevent cardiac alterations during a high altitude trek to Everest Base Camp. High Alt Med Biol 15:000-000, 2014.-Exposure to high altitude is associated with sustained, but reversible, changes in cardiac mass, diastolic function, and high-energy phosphate metabolism. Whilst the underlying mechanisms remain elusive, tissue hypoxia increases generation of reactive oxygen species (ROS), which can stabilize hypoxia-inducible factor (HIF) transcription factors, bringing about transcriptional changes that suppress oxidative phosphorylation and activate autophagy. We therefore investigated whether oral supplementation with an antioxidant, Coenzyme Q10, prevented the cardiac perturbations associated with altitude exposure. Twenty-three volunteers (10 male, 13 female, 46±3 years) were recruited from the 2009 Caudwell Xtreme Everest Research Treks and studied before, and within 48?h of return from, a 17-day trek to Everest Base Camp, with subjects receiving either no intervention (controls) or 300?mg Coenzyme Q10 per day throughout altitude exposure. Cardiac magnetic resonance imaging and echocardiography were used to assess cardiac morphology and function. Following altitude exposure, body mass fell by 3?kg in all subjects (p<0.001), associated with a loss of body fat and a fall in BMI. Post-trek, left ventricular mass had decreased by 11% in controls (p<0.05) and by 16% in Coenzyme Q10-treated subjects (p<0.001), whereas mitral inflow E/A had decreased by 18% in controls (p<0.05) and by 21% in Coenzyme Q10-treated subjects (p<0.05). Coenzyme Q10 supplementation did not, therefore, prevent the loss of left ventricular mass or change in diastolic function that occurred following a trek to Everest Base Cam
Die Rolle von Lernvoraussetzungsprofilen bei der Diagnose mathematischer Beweiskompetenz von Schüler*innen
No full textBeweise sind in der Fachmathematik von zentraler Bedeutung. Entsprechend wichtig erscheint es, Beweiskompetenz auch bei Schüler*innen adäquat aufzubauen (Reiss & Ufer, 2009). Um Schüler*innen dabei optimal zu unterstützen, müssen Lehrkräfte deren aktuellen Leistungsstand im Beweisen prozessbegleitend
diagnostizieren können. Als wichtige Indikatoren für diese Diagnose haben sich Basiswissen, Methodenwissen sowie Wissen um Problemlösestrategien der Schüler*innen herausgestellt (Reiss & Ufer, 2009). Basiswissen entspricht dem Wissen über zentrale Definitionen und Zusammenhänge; es umfasst dabei Wissen um den Begriffsinhalt, den Begriffsumfang und das Begriffsnetz (Weigand et al., 2014). Methodenwissen umfasst Wissen über den korrekten Aufbau von Beweisen, insbesondere Wissen über Beweisschema, Beweisstruktur und Beweiskette (Heinze & Reiss, 2003). Im Hinblick auf Wissen über Problemlösestrategien haben sich einerseits das Wissen über heuristische Strategien, aber auch Wissen um metakognitive Strategien wie erfolgreiche Monitoring-Strategien als hilfreiche Indikatoren erwiesen (Codreanu et al., 2022; Schoenfeld, 1992)
Qualification of a CO2 Storage Site Using an Integrated Reservoir Study
No full textAbstractIn recent years, global concerns about greenhouse gas emissions have stimulated considerable interest in CO2 storage as a potential “bridging technology”, which could reduce significantly CO2 emissions, while allowing fossil fuels to be used until alternative energy sources are more widely deployed. Flow modeling is a relevant step in the characterization of a CO2 storage site, to provide quantitative predictions of reservoir behavior and assessing the uncertainty [1].The scope of this work is to analyze the impact of CO2 injection in Pliocene offshore water-bearing sands potentially suitable for CO2 storage, through the implementation of an integrated reservoir study. The approach undertaken was first to build several geological models (local and regional), stochastically populate them with petrophysical properties and, through the gathering and generation of representative dynamic data, develop a dynamic model to simulate a set of possible CO2 injection scenarios. Furthermore a base case scenario was identified to perform a comparison between two different simulators: COORESTM, a code designed by IFPEN, and ECLIPSE300 - CO2STORETM, the Schlumberger compositional tool designed specifically for CO2 storage in saline aquifers
Compact amorphous-silicon visible-light monitor integrated in silicon nitride waveguides
No full textThis work reports on the realization of an amorphous silicon visible-light detector integrated in Si3N4 waveguides. The device is very compact (< 40 μm), has a responsivity of about 10 mA/W and a sensitivity of -40 dBm.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.QID/Hanson LabQN/Quantum Nanoscienc
The contribution of Nicolae Botnariuc to evolutionary biology using systems theory
No full textEarly this year, the Romanian Academy commemorated the centennial birthday of the evolutionary biologist Nicolae Botnariuc (13.03.1915 – 01.03.2011; Figure 1). The scientific contribution of Botnariuc has been well recognized within the Romanian community of biologists which fostered influential personalities like Emil G. Racovitza, Constantin Motaş and Radu Codreanu (cf. Iftimovici 1977; Negrea 2007). However, many aspects of his scientific achievements remain largely unknown beyond the Romanian academic space, likely due to publications with a restricted international distribution at the time the academic space of Eastern Europe was still constrained ideologically.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
The left-wing road to fascism : an investigation of the influence of 'socialist' ideas upon the political ideology of the British Union of Fascists.
No full textThe primary conclusion drawn by the thesis is that the political ideology of the BUF clearly exhibited a left-wing strand which is described as the BUF's brand of fascist
'socialism'. This strand (whilst a travestic and heretical form of socialism) considered the BUF to be more radical and virile than the Labour movement and, alone amongst political movements, capable of bringing about a national revolution which would contain a socio-economic reorientation of the country along classic socialist lines - an end to poverty, the building of houses and job creation - with Trade Unions taking a central role, within the framework of the Corporate State, in the industrial decision making process. It is not suggested that this strand was a self-contained concept within the BUF. The thesis has simply taken the heuristic step of grouping together these ideas in order to highlight
the presence of an identifiable strand within the BUF's political ideology. The thesis supports the school of academic thought which believes that fascism must be taken seriously as a genuine political ideology if it is to be understood. Fascism is viewed as an eclectic political
ideology containing a clear potential (although one not
necessarily realised) to exhibit a strand of thought which was at base a fascistic revision of socialism. In
regards to the methodology adopted by the thesis, the generic theories of fascism devised by Griffin, Sternhell, Eatwell and Payne, it was concluded that in tile context of this thesis all proved capable of predicting the potential
inherent in fascist ideology to grow from left-wing roots and exhibit a brand of fascist 'socialism'. In terms
of the theories' use as research tools it is Griffin's which stands out, due to its combination of profundity and
lucidity, which gives his theory an operational simplicity,
flexibility and heuristic quality
Heralded initialization of charge state and optical-transition frequency of diamond tin-vacancy centers
No full textDiamond tin-vacancy centers have emerged as a promising platform for quantum information science and technology. A key challenge for their use in more-complex quantum experiments and scalable applications is the ability to prepare the center in the desired charge state with the optical transition at a predefined frequency. Here we report on heralding such successful preparation using a combination of laser excitation, photon detection, and real-time logic. We first show that fluorescence photon counts collected during an optimized resonant probe pulse strongly correlate with the subsequent charge state and optical-transition frequency, enabling real-time heralding of the desired state through threshold photon counting. We then implement and apply this heralding technique to photoluminescence-excitation measurements, coherent optical driving, and an optical Ramsey experiment, finding strongly increased optical coherence with increasing threshold. Finally, we demonstrate that the prepared optical frequency follows the probe laser across the inhomogeneous linewidth, enabling tuning of the transition frequency over multiple homogeneous linewidths.QID/Hanson LabQID/Taminiau LabQN/Hanson La
A Fiber-Coupled Scanning Magnetometer with Nitrogen-Vacancy Spins in a Diamond Nanobeam
No full textMagnetic imaging with nitrogen-vacancy (NV) spins in diamond is becoming an established tool for studying nanoscale physics in condensed matter systems. However, the optical access required for NV spin readout remains an important hurdle for operation in challenging environments such as millikelvin cryostats or biological systems. Here, we demonstrate a scanning-NV sensor consisting of a diamond nanobeam that is optically coupled to a tapered optical fiber. This nanobeam sensor combines a natural scanning-probe geometry with high-efficiency through-fiber optical excitation and readout of the NV spins. We demonstrate through-fiber optically interrogated electron spin resonance and proof-of-principle magnetometry operation by imaging spin waves in an yttrium-iron-garnet thin film. Our scanning-nanobeam sensor can be combined with nanophotonic structuring to control the light-matter interaction strength and has potential for applications that benefit from all-fiber sensor access, such as millikelvin systems.QN/vanderSarlabQID/Hanson LabQN/Groeblacher LabQN/Hanson LabDynamics of Micro and Nano System
Design and conduct of 'Xtreme Alps' : a double-blind, randomised controlled study of the effects of dietary nitrate supplementation on acclimatisation to high altitude
No full textThe study of healthy human volunteers ascending to high altitude provides a robust model of the complex physiological interplay that emulates human adaptation to hypoxaemia in clinical conditions. Nitric oxide (NO) metabolism may play an important role in both adaptation to high altitude and response to hypoxaemia during critical illness at sea level. Circulating nitrate and nitrite concentrations can be augmented by dietary supplementation and this is associated with improved exercise performance and mitochondrial efficiency. We hypothesised that the administration of a dietary substance (beetroot juice) rich in nitrate would improve oxygen efficiency during exercise at high altitude by enhancing tissue microcirculatory blood flow and oxygenation. Furthermore, nitrate supplementation would lead to measurable increases in NO bioactivity throughout the body.
This methodological manuscript describes the design and conduct of the ‘Xtreme Alps’ expedition, a double-blind randomised controlled trial investigating the effects of dietary nitrate supplementation on acclimatisation to hypobaric hypoxia at high altitude in healthy human volunteers. The primary outcome measure was the change in oxygen efficiency during exercise at high altitude between participants allocated to receive nitrate supplementation and those receiving a placebo. A number of secondary measures were recorded, including exercise capacity, peripheral and microcirculatory blood flow and tissue oxygenation.
Results from this study will further elucidate the role of NO in adaption to hypoxaemia and guide clinical trials in critically ill patients. Improved understanding of hypoxaemia in critical illness may provide new therapeutic avenues for interventions that will improve survival in critically ill patients
Exploring the Process of Preservice Teachers' Diagnostic Activities in a Video-Based Simulation
No full textFormative assessment of student learning is a challenging task in the teaching profession. Both teachers’ professional vision and their pedagogical content knowledge of specific subjects such as mathematics play an important role in assessment processes. This study investigated mathematics preservice teachers’ diagnostic activities during a formative assessment task in a video-based simulation. It examined which mathematical content was important for the successful assessment of the simulated students’ mathematical argumentation skills. Beyond that, the preservice teachers’ use of different diagnostic activities was assessed and used as an indicator of their knowledge-based reasoning during the assessment situation. The results showed that during the assessment, the mathematical content focused on varied according to the level of the simulated students’ mathematical argumentation skills. In addition, explaining what had been noticed was found to be the most difficult activity for the participants. The results suggest that the examined diagnostic activities are helpful in detecting potential challenges in the assessment process of preservice teachers that need to be further addressed in teacher education. In addition, the findings illustrate that a video-based simulation may have the potential to train specific diagnostic activities by means of additional instructional support
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