Laboratory In-situ Burns of Oil on Ice

Oil spills in ice-covered waters pose unique challenges to remediation activities. In-situ burning is a potential remediation technique that has shown promising efficiency in earlier trials. An element of arctic in-situ burning is the feedback between the flame of a burn on oil-infiltrated sea ice and the melting ice beneath. A series of experiments was devised to quantify the impact of this mechanism on burn efficiency. Seven experiments were performed that started with a crude oil pool of 0.2 or 0.3 m diameter on a 1 x 1 m2 freshwater ice block. The pools were ignited and the development of the flame, ice temperatures, and ablation rates was monitored. All burns ended in a vigorous burn phase (boil-over). Burn efficiency was below 65 %. A simple pond spread model was used to derive burn rates of a spreading pond. Burn rates were mostly around 0.9 mm/min. The low burn efficiencies were found to result from significant increase of the pond area during the burn in combination with relatively thin initial oil pools. The measurements provide a starting point to address the feedback effect of pond spread and ablation on burns on an oil-infested sea ice surface layer.Laboratory In-situ Burns of Oil on IceacceptedVersio

Met and unmet need for mental health care before and during the COVID-19 pandemic

There is a concern that the coronavirus disease 2019 (COVID-19) pandemic will generate large unmet needs for mental health care. Using data from an epidemiological psychiatric diagnostic interview survey (n = 2159) conducted on a probability sample from the general population, the proportions of met and unmet need for mental health care among individuals with and without mental disorders were compared before and during the COVID-19 pandemic. The results showed no statistical difference in met and unmet need for mental health care, but point estimates were suggestive of a higher unmet need for care among those with a current mental disorder after the lock-down period.publishedVersio

Teaching physics with 670 nm diode lasers—construction of stabilized lasers and lithium cells

We describe the construction and operation of stabilized 670 nm diode lasers for use in undergraduate teaching labs. Because they emit low‐power visible radiation, 670 nm lasers are safe and aesthetically pleasing, and thus are an attractive alternative to near‐infrared diode lasers in the undergraduate laboratory. We also describe the fabrication of a robust and reliable lithium atomic vapor cell, which can be used with the 670 nm diode lasers to perform a variety of atomic physics experiments

Using Atom Interferometery to Search for New Forces

Atom interferometry is a rapidly advancing field and this Letter proposes an experiment based on existing technology that can search for new short distance forces. With current technology it is possible to improve the sensitivity by up to a factor of 10^2 and near-future advances will be able to rewrite the limits for forces with ranges from 100 um to 1 km.Comment: 5 pages, 2 figure

Influence of lasers propagation delay on the sensitivity of atom interferometers

In atom interferometers based on two photon transitions, the delay induced by the difference of the laser beams paths makes the interferometer sensitive to the fluctuations of the frequency of the lasers. We first study, in the general case, how the laser frequency noise affects the performance of the interferometer measurement. Our calculations are compared with the measurements performed on our cold atom gravimeter based on stimulated Raman transitions. We finally extend this study to the case of cold atom gradiometers.Comment: 17 pages, 6 figure

Prevalence of mental disorders, suicidal ideation and suicides in the general population before and during the COVID-19 pandemic in Norway: A population-based repeated cross-sectional analysis

Background Self-report data on mental distress indicate a deterioration of population mental health in many countries during the COVID-19 pandemic. A Norwegian epidemiological diagnostic psychiatric interview survey was conducted from January to September 2020, allowing for comparison of mental disorder and suicidal ideation prevalence from before through different pandemic periods. Prevalence of suicide deaths were compared between 2020 and 2014–2018. Methods Participants from the Trøndelag Health Study (HUNT) in Trondheim were recruited through repeated probability sampling. Using the Composite International Diagnostic Interview (CIDI 5.0) (n = 2154), current prevalence of mental disorders and suicidal ideation was examined in repeated cross-sectional analyzes. Data on suicide deaths was retrieved from the Norwegian Cause of Death Registry and compared for the months March to May in 2014–2018 and 2020. Findings Prevalence of current mental disorders decreased significantly from the pre-pandemic period (January 28th to March 11th 2020; 15•3% (95% CI 12•4–18•8)) to the first pandemic period (March 12th – May 31st; 8•7% (6•8–11•0)). Prevalences were similar between the pre-pandemic period and the interim (June 1st July 31st; 14•2% (11•4–17•5)) and second periods (August 1st-September 18th; 11•9% (9•0–15•6)). No significant differences were observed in suicidal ideation or in suicide deaths. Interpretation Except for a decrease in mental disorders in the first pandemic period, the findings suggest stable levels of mental disorders, suicidal ideation and suicide deaths during the first six months of the COVID-19 pandemic compared to pre-pandemic levels. Potential methodological and contextual explanations of these findings compared with findings from other studies are discussed.publishedVersio

Effects of oil and oil burn residues on seabird feathers

It is well known, that in case of oil spill, seabirds are among the groups of animals most vulnerable. Even small amounts of oil can have lethal effects by destroying the waterproofing of their plumage, leading to loss of insulation and buoyancy. In the Arctic these impacts are intensified. To protect seabirds, a rapid removal of oil is crucial and in situ burning could be an efficient method. In the present work exposure effects of oil and burn residue in different doses was studied on seabird feathers from legally hunted Common eider (Somateria mollissima) by examining changes in total weight of the feather and damages on the microstructure (Amalgamation Index) of the feathers before and after exposure. The results of the experiments indicate that burn residues from in situ burning of an oil spill have similar or larger fouling and damaging effects on seabird feathers, as compared to fresh oil

Using Motor Tempi to Understand Rhythm and Grammatical Skills in Developmental Language Disorder and Typical Language Development

Children with developmental language disorder (DLD) show relative weaknesses on rhythm tasks beyond their characteristic linguistic impairments. The current study compares preferred tempo and the width of an entrainment region for 5- to 7-year-old typically developing (TD) children and children with DLD and considers the associations with rhythm aptitude and expressive grammar skills in the two populations. Preferred tempo was measured with a spontaneous motor tempo task (tapping tempo at a comfortable speed), and the width (range) of an entrainment region was measured by the difference between the upper (slow) and lower (fast) limits of tapping a rhythm normalized by an individual’s spontaneous motor tempo. Data from N = 16 children with DLD and N = 114 TD children showed that whereas entrainment-region width did not differ across the two groups, slowest motor tempo, the determinant of the upper (slow) limit of the entrainment region, was at a faster tempo in children with DLD vs. TD. In other words, the DLD group could not pace their slow tapping as slowly as the TD group. Entrainment-region width was positively associated with rhythm aptitude and receptive grammar even after taking into account potential confounding factors, whereas expressive grammar did not show an association with any of the tapping measures. Preferred tempo was not associated with any study variables after including covariates in the analyses. These results motivate future neuroscientific studies of low-frequency neural oscillatory mechanisms as the potential neural correlates of entrainment-region width and their associations with musical rhythm and spoken language processing in children with typical and atypical language development