Research collaboration in solar radiometry between the University of Reunion Island and the University of Kwazulu-Natal

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.Since 2012, the Universities of KwaZulu-Natal and Reunion Island have collaborated on a joint programme of solar energy research. The initiative has two principle aims: the development of solar forecasting techniques and the expansion of solar monitoring capabilities from continental Africa into the southern Indian Ocean region. In this paper, we introduce the programme and review the progress made. A key activity is performance validation of a low-cost radiometric sensor, the Delta-T Devices SPN1, which has been operated at a UKZN ground station for comparison against reference sensors. The instrument potentially represents an opportunity to expand existing radiometric networks by reducing the cost of ground station facilities. A novel feature of the device is its use of seven thermopile sensors and a stationery shading mask which together enable the simultaneous measurement of global horizontal and diffuse horizontal irradiance. It is important that the instrument performance should first be assessed, however, so that its measurement uncertainty is known ahead of deployment. Data from the UKZN trial are included in the paper, along with a description of a meteorological classification system that may be used in solar forecasting systems. The system is based on the direct solar fraction, that is, the ratio of direct horizontal irradiance to global horizontal irradiance. A clustering methodology is described and sample data are provided to illustrate the ability of the method to segregate days into statistically significant bins.cf201

Continuously Guided Atomic Interferometry Using a Single-Zone Optical Excitation: Theoretical Analysis

In an atomic interferometer, the phase shift due to rotation is proportional to the area enclosed by the split components of the atom. However, this model is unclear for an atomic interferometer demonstrated recently by Shahriar et al., for which the atom simply passes through a single-zone optical beam, consisting of a pair of bichromatic counter-propagating beams. During the passage, the atomic wave packets in two distinct internal states couple to each other continuously. The two internal states trace out a complicated trajectory, guided by the optical beams, with the amplitude and spread of each wavepacket varying continuously. Yet, at the end of the single-zone excitation, there is an interference with fringe amplitudes that can reach a visibility close to unity. For such a situation, it is not clear how one would define the area of the interferometer, and therefore, what the rotation sensitivity of such an interferometer would be. In this paper we analyze this interferometer in order to determine its rotation sensitivity, and thereby determine its effective area. In many ways, the continuous interferometer (CI) can be thought of as a limiting version of the Borde-Chu Interferometer (BCI). We identify a quality factor that can be used to compare the performance of these interferometers. Under conditions of practical interest, we show that the rotation sensitivity of the CI can be comparable to that of the BCI. The relative simplicity of the CI (e.g., elimination of the task of precise angular alignment of the three zones) then makes it a potentially better candidate for practical atom interferometry for rotation sensing.Comment: 34 page

Meningitis during COVID -19 pandemic in the Democratic Republic of Congo: A call for concern

Meningitis is a severe infection and a significant public health challenge. The meningitis outbreak resurfaced amid the coronavirus disease 2019 (COVID-19) pandemic in the Democratic Republic of Congo (DRC). The outbreak further stressed the already overburdened health care systems with detecting, preventing etc., and treating the current coronavirus disease. The recent meningitis outbreak in the DRC has resulted in a high case fatality ratio of 50% - an incredibly worrying concern. Robust strategies are needed to curb the spread of the disease amid the COVID-19 pandemic, prevent other adverse health outcomes, and mitigate the compounding burden on the country's healthcare systems. Several measures such as vaccination campaigns, adherence to sanitation and hygiene, improved surveillance, and diagnostic capabilities could help prevent future epidemics. © 2021 The Author(s

Phonon number measurements using single photon opto-mechanics

We describe a system composed of two coupled optical cavity modes with a coupling modulated by a bulk mechanical resonator. In addition, one of the cavity modes is irreversibly coupled to a single photon source. Our scheme is an opto-mechanical realisation of the Jaynes-Cummings model where the qubit is a dual rail optical qubit while the bosonic degree of freedom is a matter degree of freedom realised as the bulk mechanical excitation. We show the possibility of engineering phonon number states of the mechanical oscillator in such a system by computing the conditional state of the mechanics after successive photon counting measurements

Mutations in ASXL1 are associated with poor prognosis across the spectrum of malignant myeloid diseases

The ASXL1 gene is one of the most frequently mutated genes in malignant myeloid diseases. The ASXL1 protein belongs to protein complexes involved in the epigenetic regulation of gene expression. ASXL1 mutations are found in myeloproliferative neoplasms (MPN), myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML). They are generally associated with signs of aggressiveness and poor clinical outcome. Because of this, a systematic determination of ASXL1 mutational status in myeloid malignancies should help in prognosis assessment

Mutations with epigenetic effects in myeloproliferative neoplasms and recent progress in treatment: Proceedings from the 5th International Post-ASH Symposium

Immediately following the 2010 annual American Society of Hematology (ASH) meeting, the 5th International Post-ASH Symposium on Chronic Myelogenous Leukemia and BCR-ABL1-Negative Myeloproliferative Neoplasms (MPNs) took place on 7–8 December 2010 in Orlando, Florida, USA. During this meeting, the most recent advances in laboratory research and clinical practice, including those that were presented at the 2010 ASH meeting, were discussed among recognized authorities in the field. The current paper summarizes the proceedings of this meeting in BCR-ABL1-negative MPN. We provide a detailed overview of new mutations with putative epigenetic effects (TET oncogene family member 2 (TET2), additional sex comb-like 1 (ASXL1), isocitrate dehydrogenase (IDH) and enhancer of zeste homolog 2 (EZH2)) and an update on treatment with Janus kinase (JAK) inhibitors, pomalidomide, everolimus, interferon-α, midostaurin and cladribine. In addition, the new ‘Dynamic International Prognostic Scoring System (DIPSS)-plus' prognostic model for primary myelofibrosis (PMF) and the clinical relevance of distinguishing essential thrombocythemia from prefibrotic PMF are discussed

How I treat splenomegaly in myelofibrosis

Symptomatic splenomegaly, a frequent manifestation of myelofibrosis (MF), represents a therapeutic challenge. It is frequently accompanied by constitutional symptoms and by anemia or other cytopenias, which make treatment difficult, as the latter are often worsened by most current therapies. Cytoreductive treatment, usually hydroxyurea, is the first-line therapy, being effective in around 40% of the patients, although the effect is often short lived. The immunomodulatory drugs, such as thalidomide or lenalidomide, rarely show a substantial activity in reducing the splenomegaly. Splenectomy can be considered in patients refractory to drug treatment, but the procedure involves substantial morbidity as well as a certain mortality risk and, therefore, patient selection is important. For patients not eligible for splenectomy, transient relief of the symptoms can be obtained with local radiotherapy that, in turn, can induce severe and long-lasting cytopenias. Allogeneic hemopoietic stem cell transplantation is the only treatment with the potential for curing MF but, due to its associated morbidity and mortality, is usually restricted to a minority of patients with poor risk features. A new class of drugs, the JAK2 inhibitors, although also palliative, are promising in the splenomegaly of MF and will probably change the therapeutic algorithm of this disease

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Abstract In an atomic interferometer, the phase shift due to rotation is proportional to the area enclosed by the split components of the atom. However, this model is unclear for an atomic interferometer demonstrated recently by Shahriar et al., for which the atom simply passes through a single-zone optical beam, consisting of a pair of bichromatic counter-propagating beams. During the passage, the atomic wave packets in two distinct internal states couple to each other continuously. The two internal states trace out a complicated trajectory, guided by the optical beams, with the amplitude and spread of each wavepacket varying continuously. Yet, at the end of the single-zone excitation, there is an interference with fringe amplitudes that can reach a visibility close to unity. For such a situation, it is not clear how one would define the area of the interferometer, and therefore, what the rotation sensitivity of such an interferometer would be. In this paper we analyze this interferometer in order to determine its rotation sensitivity, and thereby determine its effective area. In many ways, the continuous interferometer (CI) can be thought of as a limiting version of the Borde-Chu Interferometer (BCI). We identify a quality factor that can be used to compare the performance of these interferometers. Under conditions of practical interest, we show that the rotation sensitivity of the CI can be comparable to that of the BCI. The relative simplicity of the CI (e.g., elimination of the task of precise angular alignment of the three zones) then makes it a potentially better candidate for practical atom interferometry for rotation sensing. Ó 2004 Published by Elsevier B.V