Laser cooling of antihydrogen atoms Baker, C J; Bertsche, W; Capra, A ...
Nature (London),
04/2021, Volume:
592, Issue:
7852
Journal Article
Peer reviewed
Open access
The photon-the quantum excitation of the electromagnetic field-is massless but carries momentum. A photon can therefore exert a force on an object upon collision
. Slowing the translational motion of ...atoms and ions by application of such a force
, known as laser cooling, was first demonstrated 40 years ago
. It revolutionized atomic physics over the following decades
, and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen
, the antimatter atom consisting of an antiproton and a positron. By exciting the 1S-2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation
, we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude-with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S-2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic
and gravitational
studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.
Full text
Available for:
GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
Some high-income countries have deployed fourth doses of COVID-19 vaccines, but the clinical need, effectiveness, timing, and dose of a fourth dose remain uncertain. We aimed to investigate the ...safety, reactogenicity, and immunogenicity of fourth-dose boosters against COVID-19.
The COV-BOOST trial is a multicentre, blinded, phase 2, randomised controlled trial of seven COVID-19 vaccines given as third-dose boosters at 18 sites in the UK. This sub-study enrolled participants who had received BNT162b2 (Pfizer-BioNTech) as their third dose in COV-BOOST and randomly assigned them (1:1) to receive a fourth dose of either BNT162b2 (30 μg in 0·30 mL; full dose) or mRNA-1273 (Moderna; 50 μg in 0·25 mL; half dose) via intramuscular injection into the upper arm. The computer-generated randomisation list was created by the study statisticians with random block sizes of two or four. Participants and all study staff not delivering the vaccines were masked to treatment allocation. The coprimary outcomes were safety and reactogenicity, and immunogenicity (anti-spike protein IgG titres by ELISA and cellular immune response by ELISpot). We compared immunogenicity at 28 days after the third dose versus 14 days after the fourth dose and at day 0 versus day 14 relative to the fourth dose. Safety and reactogenicity were assessed in the per-protocol population, which comprised all participants who received a fourth-dose booster regardless of their SARS-CoV-2 serostatus. Immunogenicity was primarily analysed in a modified intention-to-treat population comprising seronegative participants who had received a fourth-dose booster and had available endpoint data. This trial is registered with ISRCTN, 73765130, and is ongoing.
Between Jan 11 and Jan 25, 2022, 166 participants were screened, randomly assigned, and received either full-dose BNT162b2 (n=83) or half-dose mRNA-1273 (n=83) as a fourth dose. The median age of these participants was 70·1 years (IQR 51·6–77·5) and 86 (52%) of 166 participants were female and 80 (48%) were male. The median interval between the third and fourth doses was 208·5 days (IQR 203·3–214·8). Pain was the most common local solicited adverse event and fatigue was the most common systemic solicited adverse event after BNT162b2 or mRNA-1273 booster doses. None of three serious adverse events reported after a fourth dose with BNT162b2 were related to the study vaccine. In the BNT162b2 group, geometric mean anti-spike protein IgG concentration at day 28 after the third dose was 23 325 ELISA laboratory units (ELU)/mL (95% CI 20 030–27 162), which increased to 37 460 ELU/mL (31 996–43 857) at day 14 after the fourth dose, representing a significant fold change (geometric mean 1·59, 95% CI 1·41–1·78). There was a significant increase in geometric mean anti-spike protein IgG concentration from 28 days after the third dose (25 317 ELU/mL, 95% CI 20 996–30 528) to 14 days after a fourth dose of mRNA-1273 (54 936 ELU/mL, 46 826–64 452), with a geometric mean fold change of 2·19 (1·90–2·52). The fold changes in anti-spike protein IgG titres from before (day 0) to after (day 14) the fourth dose were 12·19 (95% CI 10·37–14·32) and 15·90 (12·92–19·58) in the BNT162b2 and mRNA-1273 groups, respectively. T-cell responses were also boosted after the fourth dose (eg, the fold changes for the wild-type variant from before to after the fourth dose were 7·32 95% CI 3·24–16·54 in the BNT162b2 group and 6·22 3·90–9·92 in the mRNA-1273 group).
Fourth-dose COVID-19 mRNA booster vaccines are well tolerated and boost cellular and humoral immunity. Peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose.
UK Vaccine Task Force and National Institute for Health Research.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Renal cachexia is an important consideration in the person-centred care that is needed in end-stage renal disease (ESRD). However, given that clinical guidelines relating to renal cachexia are ...largely absent, this is an unmet care need. To inform guidelines and future renal service planning, there is an urgency to understand individuals’ experiences of renal cachexia and the interrelated experiences of the carers in their lives. We report here the protocol for an interpretative phenomenological study which will explore this lived experience. A purposive sampling strategy will recruit individuals living with ESRD who have cachexia and their carers. A maximum of 30 participants (15 per group) dependent on saturation will be recruited across two nephrology directorates, within two healthcare trusts in the United Kingdom. Individuals with renal cachexia undergoing haemodialysis will be recruited via clinical gatekeepers and their carers will subsequently be invited to participate in the study. Participants will be offered the opportunity to have a face-to-face, virtual or telephone interview. Interviews will be audio-recorded, transcribed verbatim and analysed using interpretative phenomenological analysis. NVivo, will be used for data management. Ethical approval for this study was granted by the Office for Research Ethics Committees Northern Ireland (REC Reference: 22/NI/0107). Scientific evidence tends to focus on measurable psychological, social and quality of life outcomes but there is limited research providing in-depth meaning and understanding of the views of individuals with renal disease who are experiencing renal cachexia. This information is urgently needed to better prepare healthcare providers and in turn support individuals with ESRD and their carers. This study will help healthcare providers understand what challenges individuals with ESRD, and their carers face in relation to cachexia and aims to inform future clinical practice guidelines and develop supportive interventions which recognise and respond to the needs of this population.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The availability of antiretroviral medications has transformed living with HIV infection into a manageable chronic illness, and high levels of adherence are necessary. Stigma has been identified as ...one reason for missing medication doses. The objective of this study was to explore the relationship between perceived HIV stigma and self-reported missed doses of antiretroviral medications in a 12-month, repeated measures cohort study conducted in Lesotho, Malawi, South Africa, Swaziland, and Tanzania. Data were collected from 1457 HIV-positive individuals at three times between January 2006 and March 2007. Participants completed a series of questionnaires. Of the 1457 participants, 698 were taking ARVs during the study and are included in this analysis. There was a significant relationship between perceived HIV stigma and self-report of missed medications over time (t = 6.04, p </= 0.001). Individuals who reported missing more ARV medications also reported higher levels of perceived HIV stigma. Individuals reporting fewer medication worries reported decreased stigma over the one year period (t = -4.79, p </= 0.001). While those who reported increased symptom intensity also reported increased stigma initially (t = 8.67, p </= 0.001) that remained high over time. This study provides evidence of a significant and stable correlation that documents the relationship between perceived HIV stigma and self-reported reasons for missed medications over time. These findings suggest that part of the reason for poor adherence to ARV medications is linked to the stigma experienced by people living with HIV.
This article describes the development and testing of a quantitative measure of HIV/AIDS stigma as experienced by people living with HIV/AIDS. This instrument is designed to measure perceived stigma, ...create a baseline from which to measure changes in stigma over time, and track potential progress towards reducing stigma. It was developed in three phases from 2003-2006: generating items based on results of focus group discussions; pilot testing and reducing the original list of items; and validating the instrument. Data for all phases were collected from five African countries: Lesotho, Malawi, South Africa, Swaziland and Tanzania. The instrument was validated with a sample of 1,477 persons living with HIV/AIDS from all of the five countries. The sample had a mean age of 36.1 years and 74.1% was female. The participants reported they knew they were HIV positive for an average of 3.4 years and 46% of the sample was taking antiretroviral medications. A six factor solution with 33 items explained 60.72% of the variance. Scale alpha reliabilities were examined and items that did not contribute to scale reliability were dropped. The factors included: Verbal Abuse (8 items, alpha=0.886); Negative Self-Perception (5 items, alpha=0.906); Health Care Neglect (7 items, alpha=0.832); Social Isolation (5 items, alpha=0.890); Fear of Contagion (6 items, alpha=0.795); and Workplace Stigma (2 items, alpha=0.758). This article reports on the development and validation of a new measure of stigma, HIV/AIDS Stigma Instrument-PLWA (HASI-P) providing evidence that supports adequate content and construct validity, modest concurrent validity, and acceptable internal consistency reliability for each of the six subscales and total score. The sacle is available is several African languages.
Full text
Available for:
DOBA, IJS, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Antiprotons created by laser ionization of antihydrogen are observed to rapidly escape the ALPHA trap. Further, positron plasmas heat more quickly after the trap is illuminated by laser light for ...several hours. These phenomena can be caused by patch potentials-variations in the electrical potential along metal surfaces. A simple model of the effects of patch potentials explains the particle loss, and an experimental technique using trapped electrons is developed for measuring the electric field produced by the patch potentials. The model is validated by controlled experiments and simulations.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM, UPUK
Family context exerts a strong influence on disease management among patients with chronic disease, but it is not clear which aspects of family life are most influential. This study examined the ...linkages between patient-appraised couple emotion management (conflict resolution, expressiveness, and respect) and disease management (biological, morale/depression, quality of life, and behavioral) among a relatively understudied group, Chinese American patients with type 2 diabetes. Significant main effects were found between patient-appraised couple emotion management, especially conflict resolution, and the morale component of disease management, but not the biological or behavioral components; both diabetes-specific and general relationship qualities (marital satisfaction) were independently linked to disease management. Acculturation did not qualify the findings. Similarities among ethnic groups in family and disease management relationships may be more common than differences.
Full text
Available for:
CEKLJ, FFLJ, NUK, ODKLJ, PEFLJ, UPUK
PDF
