Spatiotemporal evolution of radio wave pump-induced ionospheric phenomena near the fourth electron gyroharmonic

On 12 November 2001, the European Incoherent Scatter (EISCAT) high-frequency (HF) radio wave transmitter facility, operating in O-mode at 5.423 MHz with 550 MW effective radiated power, produced artificial optical rings which appeared immediately at transmitter turn-on and collapsed into blobs after ∼60 s while descending in altitude. A similar descent in altitude was observed in the EISCAT ultra high frequency (UHF) ion line enhancements. Likewise, the stimulated electromagnetic emission (SEE) spectra changed as the pump frequency approached the fourth electron gyroharmonic due to pump-induced variations in electron concentration. Optical recordings were made from Skibotn at 630.0 and 557.7 nm and from Ramfjord in white light. The altitude of the initial optical ring and steady state blob has been estimated by triangulation. The evolution in altitude of the optical emissions, ion line enhancements, and SEE spectra all show a similar morphology but are generally not at exactly the same height. Typically, the optical height is close to and a few kilometers below that of the radar backscatter but sometimes above it, both of which are above the SEE generation altitude. There is evidence that upper hybrid (UH) waves, which propagate perpendicular to the magnetic field line, and Langmuir (L) waves, which propagate parallel to the magnetic field line, act simultaneously to accelerate electrons even in the steady state

A Computational Method for the Image Segmentation of Pigmented Skin Lesions

Senior Project submitted to The Division of Science, Mathematics and Computing of Bard College

Electronic Cigarettes Vs. Regular Tobacco Cigarettes

Smoking is one of the most talked about subject in public health. the use of electronic cigarettes is becoming increasingly popular among smokers world wide. Smoking E- cigarettes is thought to be healthier than smoking regular tobacco cigarettes. As stated by the Centers of Disease Control and prevention (2014), cigarette smoking causes 480,000 deaths every year in the United States; that is about one in five deaths. Although, electronic cigarettes are being marketed and promoted as being healthier to smoke compared to regular tobacco cigarettes, electronic cigarettes are just as harmful to the human body as tobacco cigarettes are. For my thesis project, I am going to do a podcast. I plan on writing a descriptive script of information regarding my topic. Also, I will be working with faculty from the communications department as guidance on making a podcast. Doing a podcast on electronic cigarettes is a good way to provide information because there is not enough information of the health risks of electronic cigarettes. A podcast also provides a different way of obtaining the information for learners

Choline Chloride Eutectics: Low Temperature Applications

Deep eutectic solvents (DESs) have a lower melting point than each of their individual components due to ion dipole interactions or hydrogen bonding. Traditionally, DES are used for processing metals through plating and have many synthesis applications. DES are able to be substituted for hazardous solvents that are traditionally used for metal plating and synthesis. This, along with many other advantageous properties, appear promising for the use of DESs as solvents or for use in electrochemical systems, particularly at low temperatures. Choline chloride:propylene glycol was a novel DES synthesized and analyzed for its properties, including melting point, viscosity, conductivity, heat capacity, and heat of fusion. A 1:5 ratio of choline chloride: propylene glycol was found to be most promising at low temperatures based on these results

Adherence to individualized recall intervals for oral health examinations

Objectives: The aim of this follow-up study was to investigate whether adults attend an oral health examination (OHE) based on their individual recall interval (IRI) without a reminder recall system.Methods: The study population included adults who were attending an OHE recommended by their dentists based on their IRI in public oral healthcare clinics of Helsinki City January 1, 2009-December 31, 2009. The inclusion criteria were as follows: alive until the end of IRI, length of the IRI of 12-60 months, and study participants had not been treated successfully by a dental specialist during the IRI period (n = 41,255). We used a multinomial model to identify the factors associated with the timing of OHE. The following predictors were included: oral health indices such as Decayed Teeth and the Community Periodontal Index, the length of the IRI based on an OHE in 2009, age, gender, socioeconomic status, presence of chronic diseases, and emergency appointment. Results were presented as odds ratios with 95% confidence intervals.Results: The OHE based on IRI occurred for 7505 individuals (18.2%) and the OHE was late for 9159 individuals (22.2%). A total of 24,591 (59.6%) adults did not undergo follow-up OHE based on the IRI period of on time or late. Those who came on time for follow-up OHE experienced less caries than those who came later. There was not much difference in periodontal health between the groups. The models indicated that having an emergency appointment was associated with a higher probability of having an OHE. A long IRI (37-60 months) was associated with a higher probability of not participating in OHE even late.Conclusions: It would be beneficial for patients to take appointments based on the recall interval. The results of this study indicated that more needs to be done to increase awareness in the adult population of the benefits and availability of follow-up OHEs based on their IRI in oral healthcare.Peer reviewe

High-latitude artificial aurora using the EISCAT high-gain HF facility

The EISCAT high-frequency (HF) transmitter facility at Ramfjord, Norway, has been used to accelerate F-region electrons sufficiently to excite the oxygen atoms and nitrogen molecules, resulting in optical emissions at 630, 557.7 and 427.8 nm. During O-mode transmissions at 5.423 MHz, using 630 MW effective radiated power, in the hours after sunset on 12 November 2001 several new observations were made, including: (1) The first high-latitude observation of an HF induced optical emission at 427.8 nm and (2) Optical rings being formed at HF on followed by their collapse into a central blob. Both discoveries remain unexplained with current theories

Dispersion forces drive water oxidation in molecular ruthenium catalysts

Rational design of artificial water-splitting catalysts is central for developing new sustainable energy technology. However, the catalytic efficiency of the natural light-driven water-splitting enzyme, photosystem II, has been remarkably difficult to achieve artificially. Here we study the molecular mechanism of ruthenium-based molecular catalysts by integrating quantum chemical calculations with inorganic synthesis and functional studies. By employing correlatedab initiocalculations, we show that the thermodynamic driving force for the catalysis is obtained by modulation of π-stacking dispersion interactions within the catalytically active dimer core, supporting recently suggested mechanistic principles of Ru-based water-splitting catalysts. The dioxygen bond forms in a semi-concerted radical coupling mechanism, similar to the suggested water-splitting mechanism in photosystem II. By rationally tuning the dispersion effects, we design a new catalyst with a low activation barrier for the water-splitting. The catalytic principles are probed by synthesis, structural, and electrochemical characterization of the new catalyst, supporting enhanced water-splitting activity under the examined conditions. Our combined findings show that modulation of dispersive interactions provides a rational catalyst design principle for controlling challenging chemistries. © The Royal Society of Chemistry 2020.Peer reviewe

Who benefit from school doctors' health checks : a prospective study of a screening method

Background: School health services provide an excellent opportunity for the detection and treatment of children at risk of later health problems. However, the optimal use of school doctors' skills and expertise remains unknown. Furthermore, no validated method for screening children for school doctors' assessments exists. The aims of the study are 1) to evaluate the benefits or harm of school doctors' routine health checks in primary school grades 1 and 5 (at ages 7 and 11) and 2) to explore whether some of the school doctors' routine health checks can be omitted using study questionnaires. Methods: This is a prospective, multicenter observational study conducted in four urban municipalities in Southern Finland by comparing the need for a school doctor's assessment to the benefit gained from it. We will recruit a random sample of 1050 children from 21 schools from primary school grades 1 and 5. Before the school doctor's health check, parents, nurses and teachers fill a study questionnaire to identify any potential concerns about each child. Doctors, blinded to the questionnaire responses, complete an electronic report after the appointment, including given instructions and follow-up plans. The child, parent, doctor and researchers assess the benefit of the health check. The researchers compare the need for a doctor's appointment to the benefit gained from it. At one year after the health check, we will analyze the implementation of the doctors' interventions and follow-up plans. Discussion: The study will increase our knowledge of the benefits of school doctors' routine health checks arid assess the developed screening method. We hypothesize that targeting the health checks to the children in greatest need would increase the quality of school health services.Peer reviewe

Electric fields control water-gated proton transfer in cytochrome c oxidase

Funding Information: ACKNOWLEDGMENTS. This work was funded by the Knut and Alice Wallenberg Foundation (2019.0251 and 2019.0043 to V.R.I.K.). V.R.I.K. also acknowledges support from the German Research Foundation (DFG) via the Collaborative Research Centre (SFB1078) as Mercator Fellow. Computational resources were provided by Funding Information: the Swedish National Infrastructure for Computing (SNIC 2021/1-40, SNIC 2022/1-29) at the Center of High-Performance Computing (PDC), and by the Leibniz-Rechenzentrum. M.W. was supported by the Institute of Biotechnology, University of Helsinki. Funding Information: This work was funded by the Knut and Alice Wallenberg Foundation (2019.0251 and 2019.0043 to V.R.I.K.). V.R.I.K. also acknowledges support from the German Research Foundation (DFG) via the Collaborative Research Centre (SFB1078) as Mercator Fellow. Computational resources were provided by the Swedish National Infrastructure for Computing (SNIC 2021/1-40, SNIC 2022/1-29) at the Center of High-Performance Computing (PDC), and by the Leibniz-Rechenzentrum. M.W. was supported by the Institute of Biotechnology, University of Helsinki. Publisher Copyright: Copyright © 2022 the Author(s). Published by PNAS.Aerobic life is powered by membrane-bound enzymes that catalyze the transfer of electrons to oxygen and protons across a biological membrane. Cytochrome c oxidase (CcO) functions as a terminal electron acceptor in mitochondrial and bacterial respiratory chains, driving cellular respiration and transducing the free energy from O2 reduction into proton pumping. Here we show that CcO creates orientated electric fields around a nonpolar cavity next to the active site, establishing a molecular switch that directs the protons along distinct pathways. By combining large-scale quantum chemical density functional theory (DFT) calculations with hybrid quantum mechanics/ molecular mechanics (QM/MM) simulations and atomistic molecular dynamics (MD) explorations, we find that reduction of the electron donor, heme a, leads to dissociation of an arginine (Arg438)-heme a3 D-propionate ion-pair. This ion-pair dissociation creates a strong electric field of up to 1 V A21 along a water-mediated proton array leading to a transient proton loading site (PLS) near the active site. Protonation of the PLS triggers the reduction of the active site, which in turn aligns the electric field vectors along a second, "chemical," proton pathway. We find a linear energy relationship of the proton transfer barrier with the electric field strength that explains the effectivity of the gating process. Our mechanism shows distinct similarities to principles also found in other energy-converting enzymes, suggesting that orientated electric fields generally control enzyme catalysis.Peer reviewe