Stabilizing nuclear spins around semiconductor electrons via the interplay of optical coherent population trapping and dynamic nuclear polarization

We experimentally demonstrate how coherent population trapping (CPT) for donor-bound electron spins in GaAs results in autonomous feedback that prepares stabilized states for the spin polarization of nuclei around the electrons. CPT was realized by excitation with two lasers to a bound-exciton state. Transmission studies of the spectral CPT feature on an ensemble of electrons directly reveal the statistical distribution of prepared nuclear spin states. Tuning the laser driving from blue to red detuned drives a transition from one to two stable states. Our results have importance for ongoing research on schemes for dynamic nuclear spin polarization, the central spin problem and control of spin coherence.Comment: 5 pages, 4 figure

Optical diode based on the chirality of guided photons

Photons are nonchiral particles: their handedness can be both left and right. However, when light is transversely confined, it can locally exhibit a transverse spin whose orientation is fixed by the propagation direction of the photons. Confined photons thus have chiral character. Here, we employ this to demonstrate nonreciprocal transmission of light at the single-photon level through a silica nanofibre in two experimental schemes. We either use an ensemble of spin-polarised atoms that is weakly coupled to the nanofibre-guided mode or a single spin-polarised atom strongly coupled to the nanofibre via a whispering-gallery-mode resonator. We simultaneously achieve high optical isolation and high forward transmission. Both are controlled by the internal atomic state. The resulting optical diode is the first example of a new class of nonreciprocal nanophotonic devices which exploit the chirality of confined photons and which are, in principle, suitable for quantum information processing and future quantum optical networks

Adverse Childhood Experiences and Rate of Memory Decline From Mid to Later-Life: Evidence From the English Longitudinal Study of Ageing

Evidence on the role of early-life adversity in later-life memory decline is conflicting. We investigated the relationships between adverse childhood experiences (ACEs) and memory performance and rate of decline over a ten-year follow-up among mid-to-older adults in England. Data were from biennial interviews with 5,223 participants aged 54+ in the population-representative English Longitudinal Study of Ageing from 2006/07-2016/17. We examined self-reports of nine ACEs prior to age 16, which related to abuse, household dysfunction, and separation from family. Memory was assessed at each time point as immediate and delayed recall of 10 words. Using linear mixed-effects models with person-specific random intercepts and slopes and adjusted for baseline age, age2, sex, ethnicity, and childhood socioeconomic factors, we observed that most individual and cumulative ACE exposures had null-to-weakly negative associations with memory function and rate of decline over the 10-year follow-up. Having lived in residential or foster care was associated with lower baseline memory (adjusted β = -0.124 standard deviation units, 95% confidence interval: -0.273, -0.025), but not memory decline. Our findings suggest potential long-run impacts of residential or foster care on memory, and highlight the need for accurate and detailed exposure measures when studying ACEs in relation to later-life cognitive outcomes

Structure and stereochemistry of the base excision repair glycosylase MutY reveal a mechanism similar to retaining glycosidases.

MutY adenine glycosylases prevent DNA mutations by excising adenine from promutagenic 8-oxo-7,8-dihydroguanine (OG):A mismatches. Here, we describe structural features of the MutY active site bound to an azaribose transition state analog which indicate a catalytic role for Tyr126 and approach of the water nucleophile on the same side as the departing adenine base. The idea that Tyr126 participates in catalysis, recently predicted by modeling calculations, is strongly supported by mutagenesis and by seeing close contact between the hydroxyl group of this residue and the azaribose moiety of the transition state analog. NMR analysis of MutY methanolysis products corroborates a mechanism for adenine removal with retention of stereochemistry. Based on these results, we propose a revised mechanism for MutY that involves two nucleophilic displacement steps akin to the mechanisms accepted for 'retaining' O-glycosidases. This new-for-MutY yet familiar mechanism may also be operative in related base excision repair glycosylases and provides a critical framework for analysis of human MutY (MUTYH) variants associated with inherited colorectal cancer

Erratum: “Seed layer technique for high quality epitaxial manganite films” [AIP Advances 6, 085109 (2016)]

No abstract available

Diffractive triangulation of radiative point sources

We describe a general method to determine the location of a point source of waves relative to a twodimensional single-crystalline active pixel detector. Based on the inherent structural sensitivity of crystalline sensor materials, characteristic detector diffraction patterns can be used to triangulate the location of a wave emitter. The principle described here can be applied to various types of waves, provided that the detector elements are suitably structured. As a prototypical practical application of the general detection principle, a digital hybrid pixel detector is used to localize a source of electrons for Kikuchi diffraction pattern measurements in the scanning electron microscope. This approach provides a promising alternative method to calibrate Kikuchi patterns for accurate measurements of microstructural crystal orientations, strains, and phase distributions

Palliative care interventions in advanced dementia

BACKGROUND: Dementia is a chronic, progressive and ultimately fatal neurodegenerative disease. Advanced dementia is characterised by profound cognitive impairment, inability to communicate verbally and complete functional dependence. Usual care of people with advanced dementia is not underpinned universally by a palliative approach. Palliative care has focused traditionally on care of people with cancer, but for more than a decade, there have been calls worldwide to extend palliative care services to include all people with life-limiting illnesses in need of specialist care, including people with dementia. This review is an updated version of a review first published in 2016. OBJECTIVES: To assess the effect of palliative care interventions in advanced dementia. SEARCH METHODS: We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's Specialised Register on 7 October 2020. ALOIS contains records of clinical trials identified from monthly searches of several major healthcare databases, trial registries and grey literature sources. We ran additional searches across MEDLINE (OvidSP), Embase (OvidSP), four other databases and two trial registries on 7 October 2020 to ensure that the searches were as comprehensive and as up-to-date as possible. SELECTION CRITERIA: We searched for randomised (RCTs) and non-randomised controlled trials (nRCTs), controlled before-and-after studies and interrupted time series studies evaluating the impact of palliative care interventions for adults with advanced dementia of any type. Participants could be people with advanced dementia, their family members, clinicians or paid care staff. We included clinical interventions and non-clinical interventions. Comparators were usual care or another palliative care intervention. We did not exclude studies based on outcomes measured. DATA COLLECTION AND ANALYSIS: At least two review authors (SW, EM, PC) independently assessed all potential studies identified in the search against the review inclusion criteria. Two authors independently extracted data from eligible studies. Where appropriate, we estimated pooled treatment effects in a fixed-effect meta-analysis. We assessed the risk of bias of included studies using the Cochrane Risk of Bias tool and the overall certainty of the evidence for each outcome using GRADE. MAIN RESULTS: Nine studies (2122 participants) met the review inclusion criteria. Two studies were individually-randomised RCTs, six were cluster-randomised RCTs and one was a controlled before-and-after study. We conducted two separate comparisons: organisation and delivery of care interventions versus usual care (six studies, 1162 participants) and advance care planning interventions versus usual care (three studies, 960 participants). Two studies were carried out in acute hospitals and seven in nursing homes or long-term care facilities. For both comparisons, we found the included studies to be sufficiently similar to conduct meta-analyses. Changes to the organisation and delivery of care for people with advanced dementia may increase comfort in dying (MD 1.49, 95% CI 0.34 to 2.64; 5 studies, 335 participants; very low certainty evidence). However, the evidence is very uncertain and unlikely to be clinically significant. These changes may also increase the likelihood of having a palliative care plan in place (RR 5.84, 95% CI 1.37 to 25.02; 1 study, 99 participants; I2 = 0%; very low certainty evidence), but again the evidence is very uncertain. Such interventions probably have little effect on the use of non-palliative interventions (RR 1.11, 95% CI 0.71 to 1.72; 2 studies, 292 participants; I2 = 0%; moderate certainty evidence). They may also have little or no effect on documentation of advance directives (RR 1.46, 95% CI 0.50 to 4.25; 2 studies, 112 participants; I2 = 52%; very low certainty evidence), or whether discussions take place about advance care planning (RR 1.08, 95% CI 1.00 to 1.18; 1 study, 193 participants; I2 = 0%; very low certainty evidence) and goals of care (RR 2.36, 95% CI 1.00 to 5.54; 1 study, 13 participants; I2 = 0%; low certainty evidence). No included studies assessed adverse effects. Advance care planning interventions for people with advanced dementia probably increase the documentation of advance directives (RR 1.23, 95% CI 1.07 to 1.41; 2 studies, 384; moderate certainty evidence) and the number of discussions about goals of care (RR 1.33, 95% CI 1.11 to 1.59; 2 studies, 384 participants; moderate certainty evidence). They may also slightly increase concordance with goals of care (RR 1.39, 95% CI 1.08 to 1.79; 1 study, 63 participants; low certainty evidence). On the other hand, they may have little or no effect on perceived symptom management (MD -1.80, 95% CI -6.49 to 2.89; 1 study, 67 participants; very low certainty evidence) or whether advance care planning discussions occur (RR 1.04, 95% CI 0.87 to 1.24; 1 study, 67 participants; low certainty evidence). AUTHORS' CONCLUSIONS: The evidence on palliative care interventions in advanced dementia is limited in quantity and certainty. When compared to usual care, changes to the organisation and delivery of care for people with advanced dementia may lead to improvements in comfort in dying, but the evidence for this was of very low certainty. Advance care planning interventions, compared to usual care, probably increase the documentation of advance directives and the occurrence of discussions about goals of care, and may also increase concordance with goals of care. We did not detect other effects. The uncertainty in the evidence across all outcomes in both comparisons is mainly driven by imprecision of effect estimates and risk of bias in the included studies