Dynamic decoherence control of a solid-state nuclear quadrupole qubit

We report on the application of a dynamic decoherence control pulse sequence on a nuclear quadrupole transition in $Pr^{3+}:Y_2SiO_5$ . Process tomography is used to analyse the effect of the pulse sequence. The pulse sequence was found to increase the decoherence time of the transition to over 30 seconds. Although the decoherence time was significantly increased, the population terms were found to rapidly decay on the application of the pulse sequence. The increase of this decay rate is attributed to inhomogeneity in the ensemble. Methods to circumvent this limit are discussed.Comment: 4 pages, 6 figure

Perceived vocal morbidity in a problem asthma clinic

<p>Aims: Asthma treatment has the potential to affect patients' voices. We undertook detailed characterisation of voice morbidity in patients attending a problem asthma clinic, and we determined how patients' perceptions related to objective assessment by an experienced observer.</p> <p>Methods: Forty-three patients took part in the study. Subjects completed the self-administered voice symptom score (VoiSS) questionnaire and underwent digital voice recording. These voice recordings were scored using the grade–roughness–breathiness–asthenicity–strain system (GRBAS). Laryngoscopy was also performed.</p> <p>Results: The median VoiSS was 26 (range three to 83). VoiSS were significantly lower in the 17 patients with normal laryngeal structure and function (range four to 46; median 22), compared with the 26 patients with functional or structural laryngeal abnormality (range three to 83; median 33) (95 per cent confidence intervals for difference 0.0–21.0; p = 0.044). The overall grade score for the GRBAS scale did not differ between these two groups, and only 13 patients had a GRBAS score of one or more, recognised as indicating a voice problem. There were positive correlations between related GRBAS score and voice symptom score subscales. Although voice symptom scores were significantly more abnormal in patients with structural and functional abnormalities, this score performed only moderately well as a predictive tool (sensitivity 54 per cent; specificity 71 per cent). Nevertheless, the voice symptom score performed as well as the more labour-intensive GRBAS score (sensitivity 57 per cent; specificity 60 per cent). Patients' inhaled corticosteroid dose (median dose 1000 µg beclomethasone dipropionate or equivalent) had a statistically significant relationship with their overall grade score for the GRBAS scale (r = 0.56; p < 0.001), but not with their VoiSS. Only one patient had evidence of laryngeal candidiasis, and only two had any evidence of abnormality suggesting steroid-induced myopathy.</p> <p>Conclusions: Vocal morbidity is common in patients with asthma, and should not be immediately attributed to steroid-related candidiasis. The VoiSS merits further, prospective validation as a screening tool for ENT and/or speech and language therapy referral in patients with asthma.</p&gt

Quantum storage on subradiant states in an extended atomic ensemble

A scheme for coherent manipulation of collective atomic states is developed such that total subradiant states, in which spontaneous emission is suppressed into all directions due to destructive interference between neighbor atoms, can be created in an extended atomic ensemble. The optimal conditions for creation of such states and suitability of them for quantum storage are discussed. It is shown that in order to achieve the maximum signal-to-noise ratio the shape of a light pulse to be stored and reconstructed using a homogeneously broadened absorbtion line of an atomic system should be a time-reversed regular part of the response function of the system. In the limit of high optical density, such pulses allow one to prepare collective subradiant atomic states with near flat spatial distribution of the atomic excitation in the medium.Comment: V2: considerably revised (title, text). V3: minor changes - final version as published in PR

Chromosome position effects on gene expression in Escherichia coli K-12

In eukaryotes, the location of a gene on the chromosome is known to affect its expression, but such position effects are poorly understood in bacteria. Here, using Escherichia coli K-12, we demonstrate that expression of a reporter gene cassette, comprised of the model E. coli lac promoter driving expression of gfp, varies by ∼300-fold depending on its precise position on the chromosome. At some positions, expression was more than 3-fold higher than at the natural lac promoter locus, whereas at several other locations, the reporter cassette was completely silenced: effectively overriding local lac promoter control. These effects were not due to differences in gene copy number, caused by partially replicated genomes. Rather, the differences in gene expression occur predominantly at the level of transcription and are mediated by several different features that are involved in chromosome organization. Taken together, our findings identify a tier of gene regulation above local promoter control and highlight the importance of chromosome position effects on gene expression profiles in bacteria

Reliability of perceptions of voice quality: evidence from a problem asthma clinic population

<p>Introduction: Methods of perceptual voice evaluation have yet to achieve satisfactory consistency; complete acceptance of a recognised clinical protocol is still some way off.</p> <p>Materials and methods: Three speech and language therapists rated the voices of 43 patients attending the problem asthma clinic of a teaching hospital, according to the grade-roughness-breathiness-asthenicity-strain (GRBAS) scale and other perceptual categories.</p> <p>Results and analysis: Use of the GRBAS scale achieved only a 64.7 per cent inter-rater reliability and a 69.6 per cent intra-rater reliability for the grade component. One rater achieved a higher degree of consistency. Improved concordance on the GRBAS scale was observed for subjects with laryngeal abnormalities. Raters failed to reach any useful level of agreement in the other categories employed, except for perceived gender.</p> <p>Discussion: These results should sound a note of caution regarding routine adoption of the GRBAS scale for characterising voice quality for clinical purposes. The importance of training and the use of perceptual anchors for reliable perceptual rating need to be further investigated.</p&gt

Role of contrast-enhanced ultrasound (CEUS) in paediatric practice: an EFSUMB position statement

The use of contrast-enhanced ultrasound (CEUS) in adults is well established in many different areas, with a number of current applications deemed off-label, but the use supported by clinical experience and evidence. Paediatric CEUS is also an off-label application until recently with approval specifically for assessment of focal liver lesions. Nevertheless there is mounting evidence of the usefulness of CEUS in children in many areas, primarily as an imaging technique that reduces exposure to radiation, iodinated contrast medium and the patient-friendly circumstances of ultrasonography. This position statement of the European Federation of Societies in Ultrasound and Medicine (EFSUMB) assesses the current status of CEUS applications in children and makes suggestions for further development of this technique

Method of extending hyperfine coherence times in Pr^3+:Y_2SiO_5

In this letter we present a method for increasing the coherence time of praseodymium hyperfine ground state transitions in Pr^3+:Y_2SiO_5 by the application of a specific external magnetic field. The magnitude and angle of the external field is applied such that the Zeeman splitting of a hyperfine transition is at a critical point in three dimensions, making the first order Zeeman shift vanishingly small for the transition. This reduces the influence of the magnetic interactions between the praseodymium ions and the spins in the host lattice on the transition frequency. Using this method a phase memory time of 82ms was observed, a value two orders of magnitude greater than previously reported. It is shown that the residual dephasing is amenable quantum error correction

How Reasoning Aims at Truth

Many hold that theoretical reasoning aims at truth. In this paper, I ask what it is for reasoning to be thus aim-directed. Standard answers to this question explain reasoning’s aim-directedness in terms of intentions, dispositions, or rule-following. I argue that, while these views contain important insights, they are not satisfactory. As an alternative, I introduce and defend a novel account: reasoning aims at truth in virtue of being the exercise of a distinctive kind of cognitive power, one that, unlike ordinary dispositions, is capable of fully explaining its own exercises. I argue that this account is able to avoid the difficulties plaguing standard accounts of the relevant sort of mental teleology