Spatial structure of the color field in the SU(3) flux tube

We report on the chromoelectric and chromomagnetic fields generated by a static quark-antiquark pair at zero temperature in pure gauge SU(3). From the spatial structure of chromoelectric field we extract its nonperturbative part and discuss its properties.Comment: 7 pages, 3 figures, 2 tables, originally presented at the 36th Annual International Symposium on Lattice Field Theory, 22-28 July, 2018, Michigan State University, East Lansing, Michigan, US

Geometrical optimization for high efficiency carbon perovskite modules

The carbon based perovskite solar cell (C-PSC) has a strong commercial potential due its low manufacturing cost and its improved stability. A C-PSC consists of three mesoporous layers sandwiched between a Fluorine-doped tin oxide (FTO) substrate as bottom electrode and carbon as top electrode. However, the low conductivity of the two electrodes represents a real challenge when scaling from individual cells to modules. Here, 2D direct current simulation is used to investigate the influence of width of the active area on the performance of a single C-PSC. The same method is used to study the effect of the sub-cell’s width, the interconnection’s width and the contact resistance at the interconnection on the performance of a 10 sub-cells module connected in series. The intrinsic properties of the carbon cell are taken in account using experimental JSC and VOC as an input to the modelling. The carbon conductivity is found to be critical in defining the optimum geometry. For a 10 Ω/sq carbon sheet resistance, the optimum interconnection width is 500 μm and the sub cell width is 4.9 mm, leading to an optimum fill factor of 64%

Investigating the Superoxide Formation and Stability in Mesoporous Carbon Perovskite Solar Cells with an Aminovaleric Acid Additive

Perovskite solar cells have attracted a great deal of attention thanks to their high efficiency, ease of manufacturing, and potential low cost. However, the stability of these devices is considered their main drawback and needs to be addressed. Mesoporous carbon perovskite solar cells (m-CPSC), consisting of three mesoporous layers (TiO2/ZrO2/C) infiltrated with CH3NH3PbI3 (MAPI) perovskite, have presented excellent lifetimes of more than 10 000 h when the additive NH2(CH2)4CO2HI (5- aminovaleric acid iodide; 5-AVAI) is used to modify the perovskite structure. Yet, the role of 5-AVAI in enhancing the stability has yet to be determined. Here, superoxide-mediated degradation of MAPI m-CPSC with and without the 5-AVAI additive is studied using the fluorescence probe dihydroeth-idium for superoxide detection. In situ X-ray diffractometry shows that amino valeric acid methylammonium lead iodide (AVA-MAPI) perovskite infiltrated in mesoporous layers presents higher stability in an ambient environment under illumination, evidenced by a slower decrease of the MAPI/PbI2 peak ratio. Superoxide yield measurements demonstrate that AVA-MAPI generates more superoxide than regular MAPI when deposited on glass but generates significantly less when infiltrated in mesoporous layers. It is believed that superoxide formation in m-CPSC is dependent on a combination of competitive factors including oxygen diffusion, sample morphology, grain size, and defect concentration

Field, current, and charge distribution in a pure gauge SU(3) flux tube

The quark confinement in QCD is achieved by concentration of the chromoelectric field between the quark-antiquark pair into a flux tube, which gives rise to a linear quark-antiquark potential. We study the structure of the flux tube created by a static quark-antiquark pair in the pure gauge SU(3) theory, using lattice Monte-Carlo simulations. We calculate the spatial distribution of all three components of the chromoelectric field and perform the “zero curl subtraction” procedure to obtain the nonperturbative part of the longitudinal component of the field, which we identify as the part responsible for the formation of the flux tube. Taking the spatial derivatives of the obtained field allows us to extract the electric charge and magnetic current densities in the flux tube. The behavior of these observables under smearing and with respect to continuum scaling is investigated. Finally, we briefly discuss the role of magnetic currents in the formation of the string tension

Two-Photon Bidirectional Control and Imaging of Neuronal Excitability with High Spatial Resolution In Vivo

Summary: Sensory information is encoded within the brain in distributed spatiotemporal patterns of neuronal activity. Understanding how these patterns influence behavior requires a method to measure and to bidirectionally perturb with high spatial resolution the activity of the multiple neuronal cell types engaged in sensory processing. Here, we combined two-photon holography to stimulate neurons expressing blue light-sensitive opsins (ChR2 and GtACR2) with two-photon imaging of the red-shifted indicator jRCaMP1a in the mouse neocortex in vivo. We demonstrate efficient control of neural excitability across cell types and layers with holographic stimulation and improved spatial resolution by opsin somatic targeting. Moreover, we performed simultaneous two-photon imaging of jRCaMP1a and bidirectional two-photon manipulation of cellular activity with negligible effect of the imaging beam on opsin excitation. This all-optical approach represents a powerful tool to causally dissect how activity patterns in specified ensembles of neurons determine brain function and animal behavior. : Forli et al. developed an all-optical method to image and bidirectionally manipulate brain networks with high spatial resolution and minimal crosstalk in the intact mammalian brain. They validate the method across cell types and layers in the mouse neocortex. Keywords: optogenetics, two-photon excitation, digital holography, patterned illumination, two-photon imagin

“Write here, sanctuary” Creative writing for refugees and people seeking asylum

Background There are few research studies reporting findings from creative writing groups amongst refugees and people seeking asylum. This study evaluates the educational, wellbeing, social and satisfaction outcomes of writing groups across three cities in the UK. Methods This study employs a mixed-method design comprising: a thematic analysis of writers’ (facilitators) diaries, demographic and satisfaction survey and 14 qualitative interviews. Results The project delivered a creative writing programme for refugees and people seeking asylum in three UK cities. This evaluation has determined that it provided both educational and wellbeing outcomes for 144 attendees. Participants asserted that they had improved their English language and wellbeing. Satisfaction was extremely high across the cities. Participants reported increased confidence and an increased sense of hope. Conclusions Professionally-led creative writing groups may be effective in enabling people to help come to terms with past experiences and find ways of coping for the future

Personalized copy number and segmental duplication maps using next-generation sequencing

Despite their importance in gene innovation and phenotypic variation, duplicated regions have remained largely intractable owing to difficulties in accurately resolving their structure, copy number and sequence content. We present an algorithm (mrFAST) to comprehensively map next-generation sequence reads, which allows for the prediction of absolute copy-number variation of duplicated segments and genes. We examine three human genomes and experimentally validate genome-wide copy number differences. We estimate that, on average, 73-87 genes vary in copy number between any two individuals and find that these genic differences overwhelmingly correspond to segmental duplications (odds ratio = 135; P < 2.2 x 10(-16)). Our method can distinguish between different copies of highly identical genes, providing a more accurate assessment of gene content and insight into functional constraint without the limitations of array-based technology

Spectral response measurements of Perovskite solar cells

A new spectral response measurement routine is proposed that is universally applicable for all perovskite devices. It is aimed at improving measurement accuracy and repeatability of spectral response curves and current-voltage curve spectral mismatch factor corrections. Frequency response, effects of preconditioning as well as dependency on incident light intensity and voltage load on spectral response measurements are characterized on two differently structured perovskite device types. It is shown that device preconditioning affects the spectral response shape, causing errors in spectral mismatch factor corrections of up to 0.8% when using a reference cell with a good spectral match and a class A solar simulator. Wavelength dependent response to incident light intensity and voltage load is observed on both device types, which highlights the need to measure at short circuit current and maximum power point to correct spectral mismatch. The method with recommendations given ensures the correct measurement conditions are applied and measurements are corrected for instability in performance