Advanced multilateration theory, software development, and data processing: The MICRODOT system

The process of geometric parameter estimation to accuracies of one centimeter, i.e., multilateration, is defined and applications are listed. A brief functional explanation of the theory is presented. Next, various multilateration systems are described in order of increasing system complexity. Expected systems accuracy is discussed from a general point of view and a summary of the errors is listed. An outline of the design of a software processing system for multilateration, called MICRODOT, is presented next. The links of this software, which can be used for multilateration data simulations or operational data reduction, are examined on an individual basis. Functional flow diagrams are presented to aid in understanding the software capability. MICRODOT capability is described with respect to vehicle configurations, interstation coordinate reduction, geophysical parameter estimation, and orbit determination. Numerical results obtained from MICRODOT via data simulations are displayed both for hypothetical and real world vehicle/station configurations such as used in the GEOS-3 Project. These simulations show the inherent power of the multilateration procedure

A Method for Obtaining Cosmological Models Consistency Relations and Gaussian Processes Testing

In the present work, we apply consistency relation tests to several cosmological models, including the flat and non-flat $\Lambda$CDM models, as well as the flat XCDM model. The analysis uses a non-parametric Gaussian Processes method to reconstruct various cosmological quantities of interest, such as the Hubble parameter $H(z)$ and its derivatives from $H(z)$ data, as well as the comoving distance and its derivatives from SNe Ia data. We construct consistency relations from these quantities which should be valid only in the context of each model and test them with the current data. We were able to find a general method of constructing such consistency relations in the context of $H(z)$ reconstruction. In the case of comoving distance reconstruction, there were not a general method of constructing such relations and this work had to write an specific consistency relation for each model. From $H(z)$ data, we have analyzed consistency relations for all the three above mentioned models, while for SNe Ia data we have analyzed consistency relations only for flat and non-flat $\Lambda$CDM models. Concerning the flat $\Lambda$CDM model, some inconsistency was found, at more than $2\sigma$ c.l., with the $H(z)$ data in the interval $1.8\lesssim z\lesssim2.4$, while the other models were all consistent at this c.l. Concerning the SNe Ia data, the flat $\Lambda$CDM model was consistent in the $0<z<2.5$ interval, at $1\sigma$ c.l., while the nonflat $\Lambda$CDM model was consistent in the same interval, at 2$\sigma$ c.l.Comment: 17 pages and 7 figure

From Hubble to Snap Parameters: A Gaussian Process Reconstruction

By using recent $H(z)$ and SNe Ia data, we reconstruct the evolution of kinematic parameters $H(z)$, $q(z)$, jerk and snap, using a model-independent, non-parametric method, namely, the Gaussian Processes. Throughout the present analysis, we have allowed for a spatial curvature prior, based on Planck 18 [1] constraints. In the case of SNe Ia, we modify a python package (GaPP) [2] in order to obtain the reconstruction of the fourth derivative of a function, thereby allowing us to obtain the snap from comoving distances. Furthermore, using a method of importance sampling, we combine $H(z)$ and SNe Ia reconstructions in order to find joint constraints for the kinematic parameters. We find for the current values of the parameters: $H_0 =67.2 \pm 6.2$ km/s/Mpc, $q_0 = -0.60^{+0.21}_{-0.18}$, $j_0=0.90^{+0.75}_{-0.65}$, $s_0=-0.57^{+0.52}_{-0.31}$ at 1$\sigma$ c.l. We find that these reconstructions are compatible with the predictions from flat $\Lambda$CDM model, at least for 2$\sigma$ confidence intervals.Comment: 18 pages, 6 figure

Can the Universe decelerate in the future?

The possibility of an expanding decelerating Universe in the distant future is investigated in the context of a quintessence scalar field cosmology. Such a conceivable evolution is tested against SNe Ia and $H(z)$ cosmic chronometers data, and also through a model independent method based on Gaussian Processes. The scalar field model is an extension of the exponential Ratra-Peebles (RP) quintessential cosmology whose potential now depends on a pair of parameters ($\alpha, \lambda)$ and predicts a decelerated expansion in the future. Different from RP approach the $\alpha$ parameter allows for a decelerating cosmology in the future thereby frustrating the inevitable evolution for a de Sitter Cosmology as predicted by the cosmic concordance model ($\Lambda$CDM). The statistical model analysis is updated with the most recent SNe Ia and $H(z)$ data thereby obtaining $H_0 = 68.6\pm3.7$ km/s/Mpc, $\Omega_{\Phi0} = 0.735^{+0.083}_{-0.069}$, $\alpha < 6.56$ and $\lambda< 0.879$ (at $2\sigma$ c.l.). It is also found that the extended RP model allows for a future deceleration both for $H(z)$ and SNe Ia data. In the (model-independent) Gaussian Processes analysis, however, future deceleration is allowed only in the case of $H(z)$ data.Comment: 10 pages, 5 figures. Accepted for publication in Physical Review

Juvenile systemic lupus erythematosus in Portugal: clinical and immunological patterns of disease expression in a cohort of 56 patients

Objective: To define the pattern of disease expression and to gain better understanding in patients with juvenile onset systemic lupus erythematosus (SLE) in Portugal. Methods: The features of unselected patients with systemic lupus erythematosus who had disease onset before the age of 18 years were retrospectively analysed in three Portuguese centres with Pediatric Rheumatology Clinic over a 24-year period (1987-2011). Demographic, clinical and laboratory manifestations, therapy and outcome were assessed. Results: A cohort of 56 patients with a mean age at di- sease onset of 12.6±4.04 years (mean±1SD) (range, 1.0- -17.0 years) and a mean period of follow-up of 5.5±5.4 years. Forty six (82.1%) patients were female. The most common disease manifestations were musculoskeletal (87.5%), mucocutaneous (80.3%) and haematological abnormalities (75%). Lupus nephritis was diagnosed in 46.4% of patients and consisted of glomerular ne - phritis in all cases. Neuropsychiatric manifestations occurred in 21.4% but severe central nervous system complications were uncommon, as brain infarcts and organic brain syndrome in 4 (7.1%) patients. Antinuclear antibodies and anti-double stranded DNA were positive in most patients in (98.2% and 71.4% respec- tively), as well as low C3 and/or C4 were observed frequently (85.7%). Generally, most patients had a good response to therapy as demonstrated by a significant decreasing of SLEDAI score from disease presentation to the last evaluation. The SLEDAI at diagnosis, the maximum SLEDAI and the incidence of complications were significantly higher in patients with neurolupus and/or lupus nephritis. Therapy included oral steroids (87.5%), hydroxychloroquine (85.7%), azathioprine (55.4%), IV cyclophosphamide (28.6%) along with other drugs. Six (10.7%) patients were treated with rituximab. Long-term remission was achieved in 32%, disease was active in 68%, adverse reactions to therapy occurred in 53.6% and complications/severe manifestations in 23.2%. Two patients died, being active disease and severe infection the causes of death. Conclusions: This study suggests that in our patients the clinical and laboratory features observed were similar to juvenile systemic lupus erythematosus patients from other series. Clinical outcome was favourable in the present study. Complications from therapy were frequent. Objective: To define the pattern of disease expression and to gain better understanding in patients with juvenile onset systemic lupus erythematosus (SLE) in Portugal. Methods: The features of unselected patients with systemic lupus erythematosus who had disease onset before the age of 18 years were retrospectively analysed in three Portuguese centres with Pediatric Rheumatology Clinic over a 24-year period (1987-2011). Demographic, clinical and laboratory manifestations, therapy and outcome were assessed. Results: A cohort of 56 patients with a mean age at di- sease onset of 12.6±4.04 years (mean±1SD) (range, 1.0-17.0 years) and a mean period of follow-up of 5.5±5.4 years. Forty six (82.1%) patients were female. The most common disease manifestations were musculoskeletal (87.5%), mucocutaneous (80.3%) and haematological abnormalities (75%). Lupus nephritis was diagnosed in 46.4% of patients and consisted of glomerular nephritis in all cases. Neuropsychiatric manifestations occur red in 21.4% but severe central nervous system complications were uncommon, as brain infarcts and organic brain syndrome in 4 (7.1%) patients. Antinuclear antibodies and anti-double stranded DNA were positive in most patients in (98.2% and 71.4% respectively), as well as low C3 and/or C4 were observed frequently (85.7%). Generally, most patients had a good response to therapy as demonstrated by a significant decreasing of SLEDAI score from disease presentation to the last evaluation. The SLEDAI at diagnosis, the maximum SLEDAI and the incidence of complications were significantly higher in patients with neurolupus and/or lupus nephritis. Therapy included oral steroids (87.5%), hydroxychloroquine (85.7%), azathioprine (55.4%), IV cyclophosphamide (28.6%) along with other drugs. Six (10.7%) patients were trea- ted with rituximab. Long-term remission was achieved in 32%, disease was active in 68%, adverse reactions to therapy occurred in 53.6% and complications/severe manifestations in 23.2%. Two patients died, being active disease and severe infection the causes of death. Conclusions: This study suggests that in our patients the clinical and laboratory features observed were similar to juvenile systemic lupus erythematosus patients from other series. Clinical outcome was favourable in the present study. Complications from therapy were frequent