3,321 research outputs found

    Effect of a photonic band gap on the threshold and output power of solid-state lasers and light-emitting diodes

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    We present results for the operation of a three-level solid-state laser both with normal and with completely suppressed spontaneous emission between the lasing levels. The output power difference in these two cases drops as the pump rate is increased above threshold and is not greatly different at higher powers. The threshold pump power, although typically reduced by an order of magnitude, is not zero and our results thus throw further light on the concept of “thresholdless” lasing. The theory is also applicable to light-emitting diodes and amplifiers which function on the same principles as a laser

    Evidence update for the treatment of anaphylaxis

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    The Resuscitation Council UK has updated its Guideline for healthcare providers on the Emergency treatment of anaphylaxis. As part of this process, an evidence review was undertaken by the Guideline Working Group, using an internationally-accepted approach for adoption, adaptation, and de novo guideline development based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) evidence to decision (EtD) framework, referred to as GRADE-ADOLOPMENT. A number of significant changes have been made, which will be reflected in the updated Guideline. These include: emphasis on repeating intramuscular adrenaline doses after 5 min if symptoms of anaphylaxis do not resolve; corticosteroids (e.g. hydrocortisone) no longer being routinely recommended for the emergency treatment of anaphylaxis; interventions for reactions which are refractory to initial treatment with adrenaline; a recommendation against the use of antihistamines for the acute management of anaphylaxis; and guidance relating to the duration of observation following anaphylaxis, and timing of discharge

    The role of thermal and non-thermal processes in the ISM of the Magellanic Clouds

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    Radio continuum emission is a dust-unbiased tracer of both thermal and non-thermal processes in the interstellar medium. We present new maps of the free–free and synchrotron emission in the Magellanic Clouds (MCs) at 0.166, 1.4, and 4.8 GHz with no prior assumption about the radio non-thermal spectrum. The maps were constructed using a de-reddened H α map as a template for the thermal radio emission, which we subtract from maps of the total radio continuum emission. To de-redden the H α emission, it is important to know the fraction of dust surface density that attenuates the H α emission along the line of sight, fd. This fraction is obtained by comparing the dust opacity obtained through the infrared emission spectrum and the Balmer decrement method. In star-forming regions, the median fd is about 0.1, which is lower than that in diffuse regions by a factor of three. We obtain a global thermal radio fraction, fth, of 30 per cent (35 per cent) in the LMC (SMC) at 1.4 GHz. Furthermore, we present maps of the equipartition magnetic field strength with average values of ≃10.1μG in the LMC and ≃5.5μG in the SMC. The magnetic field is proportional to the star-formation rate to the power of 0.24 and 0.20 for the LMC and SMC, respectively. This study shows that non-thermal processes control the interstellar medium in the MCs

    Safety of trastuzumab (Herceptin®) during pregnancy: two case reports

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    We report on two cases of women on trastuzumab therapy for breast cancer who became pregnant and delivered healthy live infants. At the time of reporting the children are growing and developing normally (ages 3 and 2)

    Breast milk nutrient content and infancy growth.

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    AIM: Benefits of human breast milk (HM) in avoiding rapid infancy weight gain and later obesity could relate to its nutrient content. We tested the hypothesis that differential HM total calorie content (TCC) or macronutrient contents may be associated with infancy growth. METHODS: HM hindmilk samples were collected at ages 4-8 weeks from 614 mothers participating in a representative birth cohort, with repeated infancy anthropometry. HM triglyceride (fat), lipid analytes and lactose (carbohydrate) were measured by (1) H-NMR, and protein content by the Dumas method. TCC and %macronutrients were determined. RESULTS: In 614 HM samples, fat content was as follows: [median(IQR)]: 2.6 (1.7-3.6) g/100 mL, carbohydrate: 8.6 (8.2-8.8) g/100 mL, protein: 1.2 (1.1-1.2) g/100 mL; TCC: 61.8 (53.7-71.3) kcal/100 mL. HM of mothers exclusively breast feeding vs. mixed feeding was more calorific with higher %fat, lower %carbohydrate and lower %protein. Higher HM TCC was associated with lower 12-months body mass index (BMI)/adiposity, and lower 3-12 months gains in weight/BMI. HM %fat was inversely related to 3-12 months gains in weight, BMI and adiposity, whereas %carbohydrate was positively related to these measures. HM %protein was positively related to 12-months BMI. CONCLUSION: HM analysis showed wide variation in %macronutrients. Although data on milk intakes were unavailable, our findings suggest functional relevance of HM milk composition to infant growth.PP was supported by a MRC Clinical Training Fellowship (G1001995). The Cambridge Baby Growth Study has been supported by the European Union, the World Cancer Research Foundation International, the Medical Research Council, the NIHR Cambridge Comprehensive Biomedical Research Centre, the Newlife Foundation for disabled children, the Mothercare Group Foundation, and Mead Johnson Nutrition.This is the final version of the article. It first appeared from Wiley via https://doi.org/ 10.1111/apa.1336

    Wolbachia in the flesh: symbiont intensities in germ-line and somatic tissues challenge the conventional view of Wolbachia transmission routes

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    Symbionts can substantially affect the evolution and ecology of their hosts. The investigation of the tissue-specific distribution of symbionts (tissue tropism) can provide important insight into host-symbiont interactions. Among other things, it can help to discern the importance of specific transmission routes and potential phenotypic effects. The intracellular bacterial symbiont Wolbachia has been described as the greatest ever panzootic, due to the wide array of arthropods that it infects. Being primarily vertically transmitted, it is expected that the transmission of Wolbachia would be enhanced by focusing infection in the reproductive tissues. In social insect hosts, this tropism would logically extend to reproductive rather than sterile castes, since the latter constitute a dead-end for vertically transmission. Here, we show that Wolbachia are not focused on reproductive tissues of eusocial insects, and that non-reproductive tissues of queens and workers of the ant Acromyrmex echinatior, harbour substantial infections. In particular, the comparatively high intensities of Wolbachia in the haemolymph, fat body, and faeces, suggest potential for horizontal transmission via parasitoids and the faecal-oral route, or a role for Wolbachia modulating the immune response of this host. It may be that somatic tissues and castes are not the evolutionary dead-end for Wolbachia that is commonly thought

    Transport Through Andreev Bound States in a Graphene Quantum Dot

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    Andreev reflection-where an electron in a normal metal backscatters off a superconductor into a hole-forms the basis of low energy transport through superconducting junctions. Andreev reflection in confined regions gives rise to discrete Andreev bound states (ABS), which can carry a supercurrent and have recently been proposed as the basis of qubits [1-3]. Although signatures of Andreev reflection and bound states in conductance have been widely reported [4], it has been difficult to directly probe individual ABS. Here, we report transport measurements of sharp, gate-tunable ABS formed in a superconductor-quantum dot (QD)-normal system, which incorporates graphene. The QD exists in the graphene under the superconducting contact, due to a work-function mismatch [5, 6]. The ABS form when the discrete QD levels are proximity coupled to the superconducting contact. Due to the low density of states of graphene and the sensitivity of the QD levels to an applied gate voltage, the ABS spectra are narrow, can be tuned to zero energy via gate voltage, and show a striking pattern in transport measurements.Comment: 25 Pages, included SO

    Electro-Magnetic Nucleon Form Factors and their Spectral Functions in Soliton Models

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    It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfer tt are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to timelike tt leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.Comment: 24 pages, (RevTeX), 5 PS-figures; Data points in fig.2 and corresponding references added. Final version, to be published in Z.Physik
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