388 research outputs found
Standardized Monitoring of Post-Operative Morbidity and Mortality for the Evaluation of Thoracic Surgical Quality
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
Clinical effectiveness and cost-effectiveness of open and arthroscopic rotator cuff repair [the UK Rotator Cuff Surgery (UKUFF) randomised trial]
Peer 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
5 Standardized Monitoring of Post-Operative Morbidity and Mortality for the Evaluation of Thoracic Surgical Quality
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
The low recombining pericentromeric region of barley restricts gene diversity and evolution but not gene expression
The low-recombining pericentromeric region of the barley genome contains roughly a quarter of the genes of the species, embedded in low-recombining DNA that is rich in repeats and repressive chromatin signatures. We have investigated the effects of pericentromeric region residency upon the expression, diversity and evolution of these genes. We observe no significant difference in average transcript level or developmental RNA specificity between the barley pericentromeric region and the rest of the genome. In contrast, all of the evolutionary parameters studied here show evidence of compromised gene evolution in this region. First, genes within the pericentromeric region of wild barley show reduced diversity and significantly weakened purifying selection compared with the rest of the genome. Second, gene duplicates (ohnolog pairs) derived from the cereal whole-genome duplication event ca. 60MYa have been completely eliminated from the barley pericentromeric region. Third, local gene duplication in the pericentromeric region is reduced by 29% relative to the rest of the genome. Thus, the pericentromeric region of barley is a permissive environment for gene expression but has restricted gene evolution in a sizeable fraction of barley's genes
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
Haemophilus influenzae type b reemergence after combination immunization
An increase in Haemophilus influenzae type b (Hib) in
British children has been linked to the widespread use of a
diphtheria/tetanus/acellular pertussis combination vaccine
(DTaP-Hib). We measured anti-polyribosyl-ribitol phos-
phate antibody concentration and avidity before and after a
Hib booster in 176 children 2–4 years of age who had
received 3 doses of DTP-Hib (either DT whole cell pertus-
sis-Hib or DTaP-Hib) combination vaccine in infancy. We
also measured pharyngeal carriage of Hib. Antibody con-
centrations before and avidity indices after vaccination
were low (geometric mean concentration 0.46μg/mL, 95%
confidence interval [CI] 0.36–0.58; geometric mean avidity
index 0.16, 95% CI 0.14–0.18) and inversely related to the
number of previous doses of DTaP-Hib (p = 0.02 and
p<0.001, respectively). Hib was found in 2.1% (95% CI
0.7%–6.0%) of study participants. Our data support an
association between DTaP-Hib vaccine combinations and
clinical Hib disease through an effect on antibody concen-
tration and avidit
Interfacing a quantum dot spin with a photonic circuit
A scalable optical quantum information processor is likely to be a waveguide
circuit with integrated sources, detectors, and either deterministic
quantum-logic or quantum memory elements. With microsecond coherence times,
ultrafast coherent control, and lifetime-limited transitions, semiconductor
quantum-dot spins are a natural choice for the static qubits. However their
integration with flying photonic qubits requires an on-chip spin-photon
interface, which presents a fundamental problem: the spin-state is measured and
controlled via circularly-polarised photons, but waveguides support only linear
polarisation. We demonstrate here a solution based on two orthogonal photonic
nanowires, in which the spin-state is mapped to a path-encoded photon, thus
providing a blue-print for a scalable spin-photon network. Furthermore, for
some devices we observe that the circular polarisation state is directly mapped
to orthogonal nanowires. This result, which is physically surprising for a
non-chiral structure, is shown to be related to the nano-positioning of the
quantum-dot with respect to the photonic circuit
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