High Frequency Magnetometry with an Ensemble of Spin Qubits in Hexagonal Boron Nitride

Sensors based on spin qubits in 2D crystals offer the prospect of nanoscale sensing volumes, where the close proximity of the sensor and source could provide access to otherwise inaccessible signals. For AC magnetometry, the sensitivity and frequency range is typically limited by the noise spectrum, which determines the qubit coherence time. This poses a problem for III-V materials, as the non-zero spin of the host nuclei introduces a considerable source of magnetic noise. Here, we overcome this with a sensing protocol based on phase modulated continuous concatenated dynamic decoupling, which extends the coherence time towards the $T_1$ limit at room temperature and enables tuneable narrowband AC magnetometry. We demonstrate the protocol with an ensemble of negatively charged boron vacancies in hexagonal boron nitride, detecting in-plane AC fields within $\pm 150~\mathrm{MHz}$ of the electron spin resonance, and out-of-plane fields in the range of $\sim10-150~\mathrm{MHz}$. We measure an AC magnetic field sensitivity of $\sim1~\mathrm{\mu T/\sqrt{Hz}}$ at $\sim2.5~\mathrm{GHz}$, for a sensor volume of $\sim0.1~\mathrm{\mu m^3}$, and demonstrate that the sensor can reconstruct the AC magnetic field from a wire loop antenna. This work establishes the viability of spin defects in 2D materials for high frequency magnetometry, demonstrating sensitivities that are comparable to nitrogen vacancy centres in diamond for microscopic sensing volumes, and with wide-ranging applications across science and technology

Changes to the UK childhood immunisation schedule

This article summarises the recommendations by the Joint Committee on Vaccination and Immunisation (JCVI) for a new UK childhood immunisation schedule following the discontinuation of the Hib/MenC vaccine by the manufacturer (currently used at 12 months of age as a booster for these antigens) and the rationale behind these changes to the schedule. From late 2025, when the current stock of Hib/Men C vaccine runs out, Men C vaccination will no longer be offered to toddlers, as the adolescent Men ACWY vaccination programme is expected to effectively sustain herd immunity. To improve herd immunity against polio and sustain Hib control by maintaining the current impact on Hib carriage in toddlers, an 18-month visit will be added to the vaccination schedule, where a booster dose of DTaP/IPV/Hib or DTaP/IPV/Hib/HepB will be offered. The second MMR (measles, mumps, rubella) dose will be advanced from 40 to 18 months to improve uptake, with a recommendation that both MMR doses are offered with varicella immunisation (MMRV (measles, mumps, rubella and varicella)), as addition of varicella to the schedule has been demonstrated to be cost-effective in recent modelling reviewed by JCVI. One of the recently licensed interventions for preventing respiratory syncytial virus (RSV) in infants (a maternal bivalent RSV prefusion F protein vaccine) will be incorporated into the new schedule, which should significantly reduce RSV burden in infants. In addition, higher-valency pneumococcal vaccines with wider serotype coverage may be introduced

A questionnaire elicitation of surgeons' belief about learning within a surgical trial

PMID: 23145113 [PubMed - indexed for MEDLINE] PMCID: PMC3493499 Free PMC ArticlePeer reviewedPublisher PD

Radiocarbon dating of Early Egyptian pot residues

A number of absolute dating techniques are now used in archaeology, from dendrochronology to a variety of luminescence and radiometric methods.1 However, radiocarbon dating remains the most effective approach for the early historic periods. This is largely because of the levels of precision achievable, but also due to the diversity of materials that can be dated, and the ease with which radiocarbon dates can be connected to specific events in the past. Radiocarbon dating can be employed on all carbon-containing materials that are biogenic in origin. Common sample types include items fashioned from plant material, such as textiles and basketry, and the remains of animal and human tissue. Radiocarbon estimates denote the time elapsed since the antecedent organism ceased exchanging carbon with its environment. For human and animal remains this is invariably taken to be the time of death, and for plants it is most commonly the time at which the material was harvested or felled. With the advent of accelerator mass spectrometry (AMS) in the 1980s, it became possible to conduct radiocarbon analysis on samples several orders of magnitude smaller than preceding techniques.2 Typically, AMS can produce reliable dates on as little as 10 mg of plant material and just 250 mg of whole bone powder. As a result, AMS accounts for a large proportion of the dates made on archaeological samples. No form of radiocarbon dating can, however, provide direct estimates for the age of lithic or ceramic artefacts. The principle difficulty lies in relating any datable material obtained to the manufacture or use of the object in question. In fact, carbonaceous inclusions in such materials are likely to be of geological age, and therefore beyond the 50,000 year detection limit of the technique. Consequently, there remains a disjunction between radiocarbon results and dates based on ceramic seriation. One possibility at bridging this divide comes from the radiocarbon dating of organic residues adhered to specific ceramic types. This prospect was investigated for Early Egypt by an interdisciplinary research team from the University of Oxford, University College London and Cranfield University

Clinical effectiveness and cost-effectiveness of open and arthroscopic rotator cuff repair [the UK Rotator Cuff Surgery (UKUFF) randomised trial]

Peer reviewedPublisher PD

Performance of LED-Based Fluorescence Microscopy to Diagnose Tuberculosis in a Peripheral Health Centre in Nairobi.

Sputum microscopy is the only tuberculosis (TB) diagnostic available at peripheral levels of care in resource limited countries. Its sensitivity is low, particularly in high HIV prevalence settings. Fluorescence microscopy (FM) can improve performance of microscopy and with the new light emitting diode (LED) technologies could be appropriate for peripheral settings. The study aimed to compare the performance of LED-FM versus Ziehl-Neelsen (ZN) microscopy and to assess feasibility of LED-FM at a low level of care in a high HIV prevalence country

Prostatic trypsin-like kallikrein-related peptidases (KLKs) and other prostate-expressed tryptic proteinases as regulators of signalling via proteinase-activated receptors (PARs)

The prostate is a site of high expression of serine proteinases including members of the kallikrein-related peptidase (KLK) family, as well as other secreted and membrane-anchored serine proteinases. It has been known for some time that members of this enzyme family elicit cellular responses by acting directly on cells. More recently, it has been recognised that for serine proteinases with specificity for cleavage after arginine and lysine residues (trypsin-like or tryptic enzymes) these cellular responses are often mediated by cleavage of members of the proteinase-activated receptor (PAR) family - a four member sub-family of G protein-coupled receptors. Here, we review the expression of PARs in prostate, the ability of prostatic trypsin-like KLKs and other prostate-expressed tryptic enzymes to cleave PARs, as well as the prostate cancer-associated consequences of PAR activation. In addition, we explore the dysregulation of trypsin-like serine proteinase activity through the loss of normal inhibitory mechanisms and potential interactions between these dysregulated enzymes leading to aberrant PAR activation, intracellular signalling and cancer-promoting cellular changes

Bleach sedimentation: an opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIV

BACKGROUND: The purpose of the study was to evaluate the performance and feasibility of tuberculosis diagnosis by sputum microscopy after bleach sedimentation, compared with by conventional direct smear microscopy, in a setting of high prevalence of HIV. METHODS: In a community-based study in Kenya (a population in which 50% of individuals with tuberculosis are infected with HIV), individuals with suspected pulmonary tuberculosis submitted 3 sputum specimens during 2 consecutive days, which were examined by blind evaluation. Ziehl-Neelsen-stained smears were made of fresh specimens and of specimens that were processed with 3.5% household bleach followed by overnight sedimentation. Two different cutoffs for acid-fast bacilli (AFB) per 100 high-power fields (HPF) were used to define a positive smear: >10 AFB/100 HPF and 1 AFB/100 HPF. Four smear-positive case definitions, based on 1 or 2 positive smears with the 1 AFB or 10 AFB cutoff, were used. RESULTS: Of 1879 specimens from 644 patients, 363 (19.3%) and 460 (24.5%) were positive by bleach sedimentation microscopy, compared with 301 (16.0%) and 374 (19.9%) by direct smear microscopy, with use of the 10 AFB/100 HPF (P < .001) and 1 AFB/100 HPF (P < .001) cutoffs, respectively. Regardless of the case definition used, bleach sedimentation microscopy detected significantly more positive cases than did direct smear microscopy: 26.7% (172 of 644) versus 21.7% (140 of 644), respectively, with the case definition of 1 positive smear and the 1 AFB/100 HPF cutoff (P < .001), and 21.4% (138 of 644) versus 18.6% (120 of 644), respectively, with the case definition of 1 positive smear and the 10 AFB/100 HPF cutoff (P < .001). Inter- and intrareader reproducibility were favorable, with kappa coefficients of 0.83 and 0.91, respectively. Bleach sedimentation was relatively inexpensive and was not time consuming. CONCLUSIONS: Bleach sedimentation microscopy is an effective, simple method to improve the yield of smear microscopy in a setting of high prevalence of HIV. Further evaluation of this method, under operational conditions, is urgently needed to determine its potential as a tool for tuberculosis control