On the Analysis of VLBI Observations to GNSS Satellites

Space geodetic techniques such as Very Long Baseline Interferometry (VLBI) and Global Navigation Satellite Systems (GNSS) are used for the determination of celestial and terrestrial reference frames and Earth orientation parameters. It is of utmost importance to combine the observations from the different techniques to fully exploit the strengths and unique characteristics of the techniques, however, inaccurate local ties are problematic for a rigorous combination. To improve the link between the techniques, tests are under way to observe GNSS signals with VLBI radio telescopes directly, and to observe GNSS signals in GNSS antennas with subsequent processing in the VLBI system (“GNSS-VLBI Hybrid System”) including VLBI correlation. In both cases, the GNSS data type is the difference between the ranges from two stations to a satellite. However, it is still difficult to acquire those observations and thus we apply post-processed range measurements from a precise point positioning (PPP) solution with the C5++ software to build those single differences which are then used in the Vienna VLBI Software (VieVS). We use the CONT11 data set with identical clocks at seven sites to validate the models in VieVS and to assess the impact of the combined solution on the geodetic products

A Pulmonary Nodule due to Pulmonary Infarction Diagnosed by Video-Assisted Thoracoscopy

We report a pulmonary infarction in 68-year-old man who was referred for an asymptomatic pulmonary nodule in chest radiography. Computed tomography (CT), positron emission tomography (PET), and transthoracic needle aspiration suggested suspicion for malignancy. Video-assisted thoracoscopic surgery (VATS) was performed for histologic diagnosis. Our case is a pulmonary nodule due to pulmonary infarction diagnosed by VATS in Korea

Development of Risk Prediction Equations for Incident Chronic Kidney Disease

IMPORTANCE ‐ Early identification of individuals at elevated risk of developing chronic kidney disease  could improve clinical care through enhanced surveillance and better management of underlying health  conditions.  OBJECTIVE – To develop assessment tools to identify individuals at increased risk of chronic kidney  disease, defined by reduced estimated glomerular filtration rate (eGFR).  DESIGN, SETTING, AND PARTICIPANTS – Individual level data analysis of 34 multinational cohorts from  the CKD Prognosis Consortium including 5,222,711 individuals from 28 countries. Data were collected  from April, 1970 through January, 2017. A two‐stage analysis was performed, with each study first  analyzed individually and summarized overall using a weighted average. Since clinical variables were  often differentially available by diabetes status, models were developed separately within participants  with diabetes and without diabetes. Discrimination and calibration were also tested in 9 external  cohorts (N=2,253,540). EXPOSURE Demographic and clinical factors.  MAIN OUTCOMES AND MEASURES – Incident eGFR <60 ml/min/1.73 m2.  RESULTS – In 4,441,084 participants without diabetes (mean age, 54 years, 38% female), there were  660,856 incident cases of reduced eGFR during a mean follow‐up of 4.2 years. In 781,627 participants  with diabetes (mean age, 62 years, 13% female), there were 313,646 incident cases during a mean follow‐up of 3.9 years. Equations for the 5‐year risk of reduced eGFR included age, sex, ethnicity, eGFR, history of cardiovascular disease, ever smoker, hypertension, BMI, and albuminuria. For participants  with diabetes, the models also included diabetes medications, hemoglobin A1c, and the interaction  between the two. The risk equations had a median C statistic for the 5‐year predicted probability of  0.845 (25th – 75th percentile, 0.789‐0.890) in the cohorts without diabetes and 0.801 (25th – 75th percentile, 0.750‐0.819) in the cohorts with diabetes. Calibration analysis showed that 9 out of 13 (69%) study populations had a slope of observed to predicted risk between 0.80 and 1.25. Discrimination was  similar in 18 study populations in 9 external validation cohorts; calibration showed that 16 out of 18 (89%) had a slope of observed to predicted risk between 0.80 and 1.25. CONCLUSIONS AND RELEVANCE – Equations for predicting risk of incident chronic kidney disease developed in over 5 million people from 34 multinational cohorts demonstrated high discrimination and  variable calibration in diverse populations

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P &lt; 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P &lt; 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Serum potassium and adverse outcomes across the range of kidney function: a CKD Prognosis Consortium meta-analysis.

Aims: Both hypo- and hyperkalaemia can have immediate deleterious physiological effects, and less is known about long-term risks. The objective was to determine the risks of all-cause mortality, cardiovascular mortality, and end-stage renal disease associated with potassium levels across the range of kidney function and evaluate for consistency across cohorts in a global consortium. Methods and results: We performed an individual-level data meta-analysis of 27 international cohorts [10 general population, 7 high cardiovascular risk, and 10 chronic kidney disease (CKD)] in the CKD Prognosis Consortium. We used Cox regression followed by random-effects meta-analysis to assess the relationship between baseline potassium and adverse outcomes, adjusted for demographic and clinical characteristics, overall and across strata of estimated glomerular filtration rate (eGFR) and albuminuria. We included 1 217 986 participants followed up for a mean of 6.9 years. The average age was 55 ± 16 years, average eGFR was 83 ± 23 mL/min/1.73 m2, and 17% had moderate- to-severe increased albuminuria levels. The mean baseline potassium was 4.2 ± 0.4 mmol/L. The risk of serum potassium of >5.5 mmol/L was related to lower eGFR and higher albuminuria. The risk relationship between potassium levels and adverse outcomes was U-shaped, with the lowest risk at serum potassium of 4-4.5 mmol/L. Compared with a reference of 4.2 mmol/L, the adjusted hazard ratio for all-cause mortality was 1.22 [95% confidence interval (CI) 1.15-1.29] at 5.5 mmol/L and 1.49 (95% CI 1.26-1.76) at 3.0 mmol/L. Risks were similar by eGFR, albuminuria, renin-angiotensin-aldosterone system inhibitor use, and across cohorts. Conclusions: Outpatient potassium levels both above and below the normal range are consistently associated with adverse outcomes, with similar risk relationships across eGFR and albuminuria

Relatório de estágio em farmácia comunitária

Relatório de estágio realizado no âmbito do Mestrado Integrado em Ciências Farmacêuticas, apresentado à Faculdade de Farmácia da Universidade de Coimbr

On the Analysis of VLBI Observations to GNSS Satellites

Space geodetic techniques such as Very Long Baseline Interferometry (VLBI) and Global Navigation Satellite Systems (GNSS) are used for the determination of celestial and terrestrial reference frames and Earth orientation parameters. It is of utmost importance to combine the observations from the different techniques to fully exploit the strengths and unique characteristics of the techniques, however, inaccurate local ties are problematic for a rigorous combination. To improve the link between the techniques, tests are under way to observe GNSS signals with VLBI radio telescopes directly, and to observe GNSS signals in GNSS antennas with subsequent processing in the VLBI system (“GNSS-VLBI Hybrid System”) including VLBI correlation.In both cases, the GNSS data type is the difference between the ranges from two stations to a satellite. However, it is still difficult to acquire those observations and thus we apply post-processed range measurements from a precise point positioning (PPP) solution with the C5++ software to build those single differences which are then used in the Vienna VLBI Software (VieVS). We use the CONT11 data set with identical clocks at seven sites to validate the models in VieVS and to assess the impact of the combined solution on the geodetic products

Assessing the Impact of Global GNSS-VLBI Hybrid Observations

GNSS-VLBI hybrid observations refer to an approach where GNSS signals are received by GNSS antennas and correlated with VLBI correlators. The VLBI-like GNSS single differences (two stations to one satellite) are then analyzed together with standard VLBI observations. In this work, we use GNSS observations during CONT11, a continuous VLBI campaign over 15 days in September 2011. During CONT11, GNSS and VLBI are connected to the identical clocks at seven sites, which mean clock parameters can be regarded as site common parameters. We construct GNSS single differences between the ranges from two stations to a satellite, using post-processed range measurements from a precise point positioning (PPP) GPS solution with the C5++ software. Combining VLBI and VLBI-like GNSS delays during CONT11, we estimate station coordinates, Earth orientation parameters, and site common parameters, i.e. zenith wet delays and clock parameters with the Vienna VLBI Software (VieVS). We compare combined solutions with single technique solutions and assess the impact of GNSS-VLBI hybrid observations with respect to those parameters

Assessing the Impact of Global GNSS-VLBI Hybrid Observations

GNSS-VLBI hybrid observations refer to an approach where GNSS signals are received by GNSS antennas and correlated with VLBI correlators. The VLBI-like GNSS single differences (two stations to one satellite) are then analyzed together with standard VLBI observations. In this work, we use GNSS observations during CONT11, a continuous VLBI campaign over 15 days in September 2011. During CONT11, GNSS and VLBI are connected to the identical clocks at seven sites, which mean clock parameters can be regarded as site common parameters. We construct GNSS single differences between the ranges from two stations to a satellite, using post-processed range measurements from a precise point positioning (PPP) GPS solution with the C5++ software. Combining VLBI and VLBI-like GNSS delays during CONT11, we estimate station coordinates, Earth orientation parameters, and site common parameters, i.e. zenith wet delays and clock parameters with the Vienna VLBI Software (VieVS). We compare combined solutions with single technique solutions and assess the impact of GNSS-VLBI hybrid observations with respect to those parameters

Combination of Two Radio Space-Geodetic Techniques with VieVS during CONT14

Unlike CONT11, CONT14 does not have official information on common frequency standards for co-located sites. Nevertheless, according to Kwak et al. (2015) [1], we have a possibility to find the co-located sites, which used the same clocks, through comparing clock rates from single technique solutions. Moreover, CONT14 includes co-located VLBI radio telescopes, i.e. HOBART26 and HOBART12. Therefore, it is also a good test bed to develop the analysis strategy for future twin/sibling telescopes. In this study, we compute VLBI-like GNSS delays (GNSS single differences) between the ranges from two stations to a satellite, using phase measurements with most of the errors correctedby the c5++ software. We estimate station coordinates and site common parameters, i.e. zenith wet delays, troposphere gradients and clock parameters, with the Vienna VLBI Software. Common clock parameters are limited to the sites sharing the same frequency standard and having good performance of it during CONT14. Local tie vectors are introduced as fictitious observations for co-located instruments, GNSS-VLBI and even VLBI-VLBI, i.e. at Hobart. In this paper, we show the comparison results between the combination solutions and the single technique solutions in terms of station position repeatability during 15 days