ALMA detection of dark chromospheric holes in the quiet Sun

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar ALMA cycle on April 27, 2017, and compare them with available chromospheric observations in the UV and visible as well as with photospheric magnetograms. ALMA images clearly reveal the presence of distinct particularly dark/cool areas in the millimeter maps having temperatures as low as 60% of the normal quiet Sun at 3 mm, which are not seen in the other data. We speculate that ALMA is sensing cool chromospheric gas, whose presence had earlier been inferred from infrared CO spectra.Comment: 9 pages, 3 figures, accepted for publication in ApJ

The relationship between chromospheric emissions and magnetic field strength

Aims. We analyze observational data from 4 instruments to study the correlations between chromospheric emission, spanning the heights from the temperature minimum region to the middle chromosphere, and photospheric magnetic field. Methods: The data consist of radio images at 3.5 mm from the Berkeley-Illinois-Maryland Array (BIMA), UV images at 1600 A from TRACE, Ca II K-line filtergrams from BBSO, and MDI/SOHO longitudinal photospheric magnetograms. For the first time interferometric millimeter data with the highest currently available resolution are included in such an analysis. We determine various parameters of the intensity maps and correlate the intensities with each other and with the magnetic field. Results: The chromospheric diagnostics studied here show a pronounced similarity in their brightness structures and map out the underlying photospheric magnetic field relatively well. We find a power law to be a good representation of the relationship between photospheric magnetic field and emission from chromospheric diagnostics at all wavelengths. The dependence of chromospheric brightness on magnetic field is found to be different for network and internetwork regions.Comment: 13 pages, 14 figures, 3 table

The chromosphere above sunspots at millimeter wavelengths

Aims: The aim of this paper is to demonstrate that millimeter wave data can be used to distinguish between various atmospheric models of sunspots, whose temperature structure in the upper photosphere and chromosphere has been the source of some controversy. Methods: We use observations of the temperature contrast (relative to the quiet Sun) above a sunspot umbra at 3.5 mm obtained with the Berkeley-Illinois-Maryland Array (BIMA), complemented by submm observations from Lindsey & Kopp (1995) and 2 cm observations with the Very Large Array. These are compared with the umbral contrast calculated from various atmospheric models of sunspots. Results: Current mm and submm observational data suggest that the brightness observed at these wavelengths is low compared to the most widely used sunspot models. These data impose strong constraints on the temperature and density stratifications of the sunspot umbral atmosphere, in particular on the location and depth of the temperature minimum and the location of the transition region. Conclusions: A successful model that is in agreement with millimeter umbral brightness should have an extended and deep temperature minimum (below 3000 K). Better spatial resolution as well as better wavelength coverage are needed for a more complete determination of the chromospheric temperature stratification above sunspot umbrae.Comment: 9 pages, 11 figures. http://www.aanda.org/articles/aa/abs/2014/01/aa21321-13/aa21321-13.htm

Millimeter radiation from a 3D model of the solar atmosphere II. Chromospheric magnetic field

We use state-of-the-art, three-dimensional non-local thermodynamic equilibrium (non-LTE) radiative magnetohydrodynamic simulations of the quiet solar atmosphere to carry out detailed tests of chromospheric magnetic field diagnostics from free-free radiation at millimeter and submillimeter wavelengths (mm/submm). The vertical component of the magnetic field was deduced from the mm/submm brightness spectra and the degree of circular polarization synthesized at millimeter frequencies. We used the frequency bands observed by the Atacama Large Millimeter/Submillimeter Array (ALMA) as a convenient reference. The magnetic field maps obtained describe the longitudinal magnetic field at the effective formation heights of the relevant wavelengths in the solar chromosphere. The comparison of the deduced and model chromospheric magnetic fields at the spatial resolution of both the model and current observations demonstrates a good correlation, but has a tendency to underestimate the model field. The systematic discrepancy of about 10 percent is probably due to averaging of the restored field over the heights contributing to the radiation, weighted by the strength of the contribution. On the whole, the method of probing the longitudinal component of the magnetic field with free-free emission at mm/submm wavelengths is found to be applicable to measurements of the weak quiet-Sun magnetic fields. However, successful exploitation of this technique requires very accurate measurements of the polarization properties (primary beam and receiver polarization response) of the antennas, which will be the principal factor that determines the level to which chromospheric magnetic fields can be measured. Consequently, high-resolution and high-precision observations of circularly polarized radiation at millimeter wavelengths can be a powerful tool for producing chromospheric longitudinal magnetograms.Comment: 12 pages, 13 figures, accepted for publication in A&

Measuring Entangled Qutrits and Their Use for Quantum Bit Commitment

We produce and holographically measure entangled qudits encoded in transverse spatial modes of single photons. With the novel use of a quantum state tomography method that only requires two-state superpositions, we achieve the most complete characterisation of entangled qutrits to date. Ideally, entangled qutrits provide better security than qubits in quantum bit-commitment: we model the sensitivity of this to mixture and show experimentally and theoretically that qutrits with even a small amount of decoherence cannot offer increased security over qubits.Comment: Paper updated to match published version; 5 pages, 4 figures, images have been included at slightly lower quality for the archiv

ALMA Discovery of Solar Umbral Brightness Enhancement at {\lambda}=3 mm

We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are amongst the most prominent features on the solar surface, but many of their aspects are surprisingly poorly understood. We analyzed a {\lambda}=3 mm (100 GHz) mosaic image obtained by ALMA, which includes a large sunspot within the active region AR12470 on December 16, 2015. The 3 mm map has a field-of-view and spatial resolution, which is the highest spatial-resolution map of an entire sunspot in this frequency range. We find a gradient of 3 mm brightness from a high value in the outer penumbra to a low value in the inner penumbra/outer umbra. Within the inner umbra, there is a marked increase in 3mm brightness temperature, which we call an umbral brightness enhancement. This enhanced emission corresponds to a temperature excess of 800 K relative to the surrounding inner penumbral region and coincides with excess brightness in the 1330 and 1400 {\AA} slitjaw images of the Interface Region Imaging Spectrograph (IRIS), adjacent to a partial lightbridge. This {\lambda}=3 mm brightness enhancement may be an intrinsic feature of the sunspot umbra at chromospheric heights, such as a manifestation of umbral flashes, or it could be related to a coronal plume since the brightness enhancement was coincident with the footpoint of a coronal loop observed at 171 {\AA}.Comment: 16 pages, 5 figures, accepted for publication in ApJ Lette

CRISPR-Mediated Protein Tagging with Nanoluciferase to Investigate Native Chemokine Receptor Function and Conformational Changes

© 2020 The Authors G protein-coupled receptors are a major class of membrane receptors that mediate physiological and pathophysiological cellular signaling. Many aspects of receptor activation and signaling can be investigated using genetically encoded luminescent fusion proteins. However, the use of these biosensors in live cell systems requires the exogenous expression of the tagged protein of interest. To maintain the normal cellular context here we use CRISPR/Cas9-mediated homology-directed repair to insert luminescent tags into the endogenous genome. Using NanoLuc and bioluminescence resonance energy transfer we demonstrate fluorescent ligand binding at genome-edited chemokine receptors. We also demonstrate that split-NanoLuc complementation can be used to investigate conformational changes and internalization of CXCR4 and that recruitment of β-arrestin2 to CXCR4 can be monitored when both proteins are natively expressed. These results show that genetically encoded luminescent biosensors can be used to investigate numerous aspects of receptor function at native expression levels

Assessing wellbeing at school entry using the strengths and difficulties questionnaire: professional perspectives

<p>Background: Emotional and behavioural disorders in early childhood are related to poorer academic attainment and school engagement, and difficulties already evident at the point of starting school can affect a child’s later social and academic development. Successful transfer from pre-school settings to primary education is helped by communication between pre-school staff and primary school teachers. Typically, in Scotland, pre-school establishments prepare individual profiles of children before they start school around the age of five years, highlighting their strengths and development needs, for transfer to primary schools. There is, however, no consistent approach to the identification of potential social, emotional and behavioural problems. In 2010, in one local authority area in Scotland, the Strengths and Difficulties Questionnaire (SDQ) was introduced for children about to start school as a routine, structured, component of the transition process to help teachers plan support arrangements for classes and individual children. The SDQ assesses emotional, conduct, hyperactivity/ inattention and peer-relationship problems as well as pro-social behaviour. In order to be an effective means of communicating social and emotional functioning, the use of instruments such as the SDQ needs to be practicable. Finding out the views of pre-school education staff with experience of assessing children using the SDQ was, therefore, essential to establish its future utility.</p> <p>Aim: The purpose of this study was to explore the views of pre-school education staff about assessing social and emotional wellbeing of children at school entry using the SDQ. The objectives were to examine the opinions of pre-school workers about completing the SDQ and to elicit their thoughts on the value of doing this and their perceptions of the usefulness of the information collected.</p> <p>Method: Pre-school establishments were approached using a purposive sampling strategy in order to achieve a mix of local authority (n=14) and ‘partnership’ establishments (n=8) as well as different socio-economic areas. Semi-structured interviews (n=25) were conducted with pre-school head teachers (n=14) and child development officers (n=11) in order to explore the process of completing the SDQ along with perceptions of its value. The interviews were transcribed verbatim and analysed thematically.</p> <p>Results: In general, staff in pre-school establishments viewed the use of the SDQ positively. It was seen as a chance to highlight the social and emotional development of children rather than just their academic or educational ability. Most felt that the SDQ had not identified anything they did not already know about a child. A minority, nevertheless, suggested that a previously unrecognised potential difficulty was brought to light, most commonly emotional problems. Completing the SDQ was felt to be relatively straightforward even though the staff felt under pressure from competing priorities. Concerns were, however, raised about the potential of labelling a child at an early stage of formal education.</p> <p>Conclusion: The findings from this small scale study suggest that, from the point of view of pre-school education staff, it is feasible to assess children systematically for social and behavioural problems as part of the routine transition process at school entry.</p&gt

A More Generalizable Method to Evaluate Changes in Health Care Costs with Changes in Health Risks Among Employers of All Sizes

The objective of this study was to estimate the association between changes in health care expenditures relative to changes in health risk status for employers of all sizes. Repeat health risk assessments (HRAs) were obtained from 50,005 employees and spouses with 2 years of health plan enrollment, and from 37,559 employees and spouses with 3 years of enrollment in employer-sponsored medical coverage. Changes in health care expenditures were measured from the year before completion of the first HRA to the years before and after the completion of the second HRA. Propensity score weighting was used to adjust for those who did not repeat the HRA so results could be extrapolated to the larger population. Propensity score weighted multiple regression analyses were used to estimate the relationship between changes in health care expenditures with changes in risk status for 9 risk categories. Significantly higher health care expenditures were associated with those who moved from low risk to medium or high risk, compared to those who remained low risk. Expenditure reductions estimated for those who improved their health status from high risk to medium or low risk were not statistically significant. This study is unique because of its large sample size, its use of data from a wide range of employer sizes, and its efforts to extend generalizability to those who did not complete both HRAs. These results demonstrate that the potential for short-term health care savings may be greater for programs that help maintain low risk than for programs focused on risk reduction. (Population Health Management 2014;17:297?305)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140183/1/pop.2013.0103.pd