Plasma electrolytes in healthy individuals and elective surgical patients in Khartoum

Objectives: This study aimed to investigate if the frequently observed low preoperative values of the plasma electrolytes Na+, K+, and Ca+2 in our surgical patients, in Khartoum, is a reflection of their levels in the population at large or it is a genuine finding in patients. Methods: 90 male and female subjects were included in this study. 60 healthy, young and elderly individuals were selected randomly from amongst medical students and employees of the University of Khartoum. 30 elective orthopedic and general surgical patients were randomly selected from Khartoum teaching hospital. Plasma Na+ and K+ were measured using a digital flammometer, and plasma Ca+2was measured using a spectrophotometer. Results were compared to international data using the Z test. Comparison between the groups in the study was done using the student t-test.Results: Plasma Na+, K+, and Ca+2of the healthy subjects and the surgical patients were found to be low compared to the international reference values. Plasma K+ is higher and Ca+2is lower in the older subjects when compared to young ones. Conclusion: a larger study is needed to set the normal values for plasma electrolytes in the Sudan. The high environmental temperature and nature of our diets could be the reason for the observed differences between our subjects and international reference values Keywords: plasma Na+, K+, Ca+2, digital flammomete

Hirschisprung’s disease: Factors Affecting the Outcome at The National Ribat University Hospital, Khartoum, Sudan, 2007 to 2011

Background: Hirschsprung's disease (HSD) remains the most frequent cause of child intestinal obstruction.Objectives: to evaluate the effect of different factors at the final outcome, postoperative complications and the hospital stay of children with HSD.Methodology: It is a retro-prospective analytical observational hospital based study, involving all the cases presented initially to the Paediatric Surgery Centre at the National Ribat University Hospital and confirmed to be a case of HSD. The data were collected using a questionnaire and analyzed by the software SPSS version 17.Results: Sixty four patients were involved in this study with male to female ratio of 5:1. The mean age at the first time of presentation was 9 days and the bulk of the patients seen from the center of Sudan. The emergency presentation accounted for 21.9% of the cases with the delayed passage ofmeconium and constipation as the main presenting symptoms. Complications occur mainly at day 13 post operatively with colostomy prolapse as the commonest type of complications. The age of the patients at the time of Pull Through Procedure (PTP) was ranging between 7 to 72 months and the mean body weight found to be 11.94 kg. Complicationsfollowing PTP occur in 18.8% of the cases, with wound infection accounting for 15.6% of the cases. The total duration of hospital stay post operatively after reversal of colostomy was found to range between 6 and 60 days with a mean of 8.77 days and SD of ± 6.657.Conclusion: The average hospital frequency of HSD in our study is  compared to that encountered in European countries and Northern  American countries. Early diagnosis and treatment is essential for better outcome. Emergency presentation, age and the weight at Pull Through Operation and at the time of closure of colostomy, significantly affect the outcome and prolong the hospital stay.Key words: Hirschsprung's Disease, colostomy, Pull Through Operation

Integrable models: from dynamical solutions to string theory

We review the status of integrable models from the point of view of their dynamics and integrability conditions. Some integrable models are discussed in detail. We comment on the use it is made of them in string theory. We also discuss the Bethe Ansatz solution of the SO(6) symmetric Hamiltonian with SO(6) boundary. This work is especially prepared for the seventieth anniversaries of Andr\'{e} Swieca (in memoriam) and Roland K\"{o}berle.Comment: 24 pages, to appear in Brazilian Journal of Physic

Sudden natural death in Khartoum Mortuary

Background: The sudden natural death is defined as: Death occurs within 24 hours from the onset of symptoms. The disclosing of the causes of sudden natural death is important for prevention and improving outcome. The objectives of this study were to determine the causes of sudden natural death in Khartoum Mortuary Methods: Descriptive, cross- sectional study of natural sudden death in Khartoum Mortuary, which was located in Khartoum Teaching Hospital and offers services to the state. The autopsy records of 2007, which were 150, were considered. Data were collected by a structured check list, and analysis was done by the SPSS soft ware. Results:The most important systems involved in sudden natural deaths were respiratory (49.3%), cardiovascular (24%), gastro intestinal (15.3%) and cerebral (4%), while the leading causes of sudden natural death were pneumonia (20%), myocardial infarction (17.3%) and tuberculosis (14%). Sudden natural death occurred in slightly higher ratio in the age group 40 years and below (50.1%), males were dominating (83%). Conclusion: The commonest causes of sudden natural death, which were pneumonia, myocardial infarction and tuberculosis, were different from the literature in which the commonest causes were myocardial infarction followed by pulmonary embolism. The study highlighted the importance of respiratory diseases besides myocardial infarction as leading causes of sudden natural death, and the need for further researches in this issue. Keywords: pneumonia, myocardial infarction and tuberculosis, postmortem Sudan Journal of Medical Science Vol. 3 (4) 2008: pp. 319-32

The BINGO project: VII. Cosmological forecasts from 21 cm intensity mapping

Context. The 21 cm line of neutral hydrogen (HI) opens a new avenue in our exploration of the structure and evolution of the Universe. It provides complementary data to the current large-scale structure (LSS) observations with different systematics, and thus it will be used to improve our understanding of the Icold dark matter (ICDM) model. This will ultimately constrain our cosmological models, attack unresolved tensions, and test our cosmological paradigm. Among several radio cosmological surveys designed to measure this line, BINGO is a single-dish telescope mainly designed to detect baryon acoustic oscillations (BAOs) at low redshifts (0.127 < z < 0.449). Aims. Our goal is to assess the fiducial BINGO setup and its capabilities of constraining the cosmological parameters, and to analyze the effect of different instrument configurations. Methods. We used the 21 cm angular power spectra to extract cosmological information about the HI signal and the Fisher matrix formalism to study BINGO's projected constraining power. Results. We used the Phase 1 fiducial configuration of the BINGO telescope to perform our cosmological forecasts. In addition, we investigated the impact of several instrumental setups, taking into account some instrumental systematics, and different cosmological models. Combining BINGO with Planck temperature and polarization data, the projected constraint improves from a 13% and 25% precision measurement at the 68% confidence level with Planck only to 1% and 3% for the Hubble constant and the dark energy (DE) equation of state (EoS), respectively, within the wCDM model. Assuming a Chevallier- Polarski- Linder (CPL) parameterization, the EoS parameters have standard deviations given by w0 = 0.30 and wa = 1.2, which are improvements on the order of 30% with respect to Planck alone. We also compared BINGO's fiducial forecast with future SKA measurements and found that, although it will not provide competitive constraints on the DE EoS, significant information about HI distribution can be acquired. We can access information about the HI density and bias, obtaining 8.5% and 6% precision, respectively, assuming they vary with redshift at three independent bins. BINGO can also help constrain alternative models, such as interacting dark energy and modified gravity models, improving the cosmological constraints significantly. Conclusions. The fiducial BINGO configuration will be able to extract significant cosmological information from the HI distribution and provide constraints competitive with current and future cosmological surveys. It will also help in understanding the HI physics and systematic effects

The BINGO project: V. Further steps in component separation and bispectrum analysis

Context. Observing the neutral hydrogen distribution across the Universe via redshifted 21 cm line intensity mapping constitutes a powerful probe for cosmology. However, the redshifted 21 cm signal is obscured by the foreground emission from our Galaxy and other extragalactic foregrounds. This paper addresses the capabilities of the BINGO survey to separate such signals. Aims. We show that the BINGO instrumental, optical, and simulations setup is suitable for component separation, and that we have the appropriate tools to understand and control foreground residuals. Specifically, this paper looks in detail at the different residuals left over by foreground components, shows that a noise-corrected spectrum is unbiased, and shows that we understand the remaining systematic residuals by analyzing nonzero contributions to the three-point function. Methods. We use the generalized needlet internal linear combination, which we apply to sky simulations of the BINGO experiment for each redshift bin of the survey. We use binned estimates of the bispectrum of the maps to assess foreground residuals left over after component separation in the final map. Results. We present our recovery of the redshifted 21 cm signal from sky simulations of the BINGO experiment, including foreground components. We test the recovery of the 21 cm signal through the angular power spectrum at different redshifts, as well as the recovery of its non-Gaussian distribution through a bispectrum analysis. We find that non-Gaussianities from the original foreground maps can be removed down to, at least, the noise limit of the BINGO survey with such techniques. Conclusions. Our component separation methodology allows us to subtract the foreground contamination in the BINGO channels down to levels below the cosmological signal and the noise, and to reconstruct the 21 cm power spectrum for different redshift bins without significant loss at multipoles 20≲ l ≲ 500. Our bispectrum analysis yields strong tests of the level of the residual foreground contamination in the recovered 21 cm signal, thereby allowing us to both optimize and validate our component separation analysis

Data Deluge in Astrophysics: Photometric Redshifts as a Template Use Case

Astronomy has entered the big data era and Machine Learning based methods have found widespread use in a large variety of astronomical applications. This is demonstrated by the recent huge increase in the number of publications making use of this new approach. The usage of machine learning methods, however is still far from trivial and many problems still need to be solved. Using the evaluation of photometric redshifts as a case study, we outline the main problems and some ongoing efforts to solve them.Comment: 13 pages, 3 figures, Springer's Communications in Computer and Information Science (CCIS), Vol. 82

The BINGO project: IV. Simulations for mission performance assessment and preliminary component separation steps

Aims. The large-scale distribution of neutral hydrogen (HI) in the Universe is luminous through its 21 cm emission. The goal of the Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) radio telescope is to detect baryon acoustic oscillations at radio frequencies through 21 cm intensity mapping (IM). The telescope will span the redshift range 0.127<z<0.449 with an instantaneous field-of-view of 14.75 - 6.0. Methods. In this work we investigate different constructive and operational scenarios of the instrument by generating sky maps as they would be produced by the instrument. In doing this we use a set of end-to-end IM mission simulations. The maps will additionally be used to evaluate the efficiency of a component separation method (GNILC). Results. We have simulated the kind of data that would be produced in a single-dish IM experiment such as BINGO. According to the results obtained, we have optimized the focal plane design of the telescope. In addition, the application of the GNILC method on simulated data shows that it is feasible to extract the cosmological signal across a wide range of multipoles and redshifts. The results are comparable with the standard principal component analysis method

On the classical equivalence of monodromy matrices in squashed sigma model

We proceed to study the hybrid integrable structure in two-dimensional non-linear sigma models with target space three-dimensional squashed spheres. A quantum affine algebra and a pair of Yangian algebras are realized in the sigma models and, according to them, there are two descriptions to describe the classical dynamics 1) the trigonometric description and 2) the rational description, respectively. For every description, a Lax pair is constructed and the associated monodromy matrix is also constructed. In this paper we show the gauge-equivalence of the monodromy matrices in the trigonometric and rational description under a certain relation between spectral parameters and the rescalings of sl(2) generators.Comment: 32pages, 3figures, references added, introduction and discussion sections revise

The BINGO Project: III. Optical design and optimization of the focal plane

Context. The Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) telescope was designed to measure the fluctuations of the 21 cm radiation arising from the hyperfine transition of neutral hydrogen. It is also aimed at measuring the baryon acoustic oscillations (BAO) from such fluctuations, thereby serving as a pathfinder to future, deeper intensity mapping surveys. The requirements for the Phase 1 of the projects consider a large reflector system (two 40 m-class dishes in a crossed-Dragone configuration) illuminating a focal plane with 28 horns to measure the sky, with two circular polarizations in a drift scan mode to produce measurements of the radiation in intensity (I) as well as the circular (V) polarization. Aims. In this paper, we present the optical design for the instrument. We describe the optical arrangement of the horns in the focal plane to produce a homogeneous and well-sampled map after the end of Phase 1, as well as the intensity and polarization properties of the beams. Our analysis provides an optimal model for the location of the horns in the focal plane, producing a homogeneous and Nyquist-sampled map after the nominal survey time. Methods. We used the GRASP package to model the focal plane arrangement and performed several optimization tasks to arrive at the current configuration, including an estimation of the sidelobes corresponding to the diffraction patterns of the two mirrors. The final model for the focal plane was defined through a combination of neural network and other direct optimization methods. Results. We arrived at an optimal configuration for the optical system that includes the focal plane positioning and the beam behavior of the instrument. We present an estimate of the expected sidelobes both for intensity and polarization, as well as the effect of band averaging on the final sidelobes, as well as an estimation of the cross-polarization leakage for the final configuration. Conclusions. We conclude that the chosen optical design meets the requirements for the project in terms of polarization purity and area coverage as well as a homogeneity of coverage so that BINGO can perform a successful BAO experiment. We further conclude that the requirements on the placement and rms error on the mirrors are also achievable so that a successful experiment can be conducted