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To assist gas distribution companies to effectively monitor their infrastructure and locate gas leaks, this paper considers the use of an Unmanned Aerial Vehicle (UAV) carrying a methane sensor to survey a region for gas leaks. As the UAV collects in situ measurements, it gathers evidence regarding the presence or absence of leaks in the region. To relate the UAV measurement to a region on the ground, we propose to use Upwind Survey Regions (USRs). If the UAV collects a measurement of high gas concentration, the USR represents a region that is likely to contain the leak. Likewise, if the UAV collects a measurement of low gas concentration, the USR represents a region that is likely to be clear of gas leaks. We propose a framework to process the measurements and produce a survey map indicating areas that can be reliably cleared of gas leaks and areas that may contain gas leaks. Our framework is composed of two steps: 1) mapping UAV measurements into USRs on the ground; and 2) fusing the various mapped USRs to produce the survey map. We discuss how USRs can be estimated and we test our framework using both simulated and real UAV flights.

Abstract Left ventricular hypertrophy is a risk factor for cardiovascular mortality in patients on peritoneal dialysis (PD). Because icodextrin has a greater ultrafiltration power compared with glucose-based solutions for long dwell, it could improve left ventricular mass by reducing fluid overload. This was a randomized clinical trial that included patients on PD recruited from 2 teaching hospitals, in Sao Paulo—Brazil. Patients were allocated to the control glucose group (GLU) or the intervention icodextrin (ICO) group. Clinical and cardiac magnetic resonance image (MRI) parameters were evaluated at baseline and 6 months after randomization. The primary outcome was the change in left ventricular mass adjusted by surface area (ΔLVMI), measured by cardiac MRI. A total of 22 patients completed the study (GLU, N = 12 and ICO, N = 10). Baseline characteristics such as age, sex, underlying disease, and time on dialysis were similar in both groups. At baseline, 17 patients (77.3%) presented with left ventricular hypertrophy with no difference between groups (p = 0.748). According to the total body water (TBW)/extracellular water (ECW) ratio, 36.8% and 80% of patients from GLU and ICO groups, respectively, were considered hypervolemic (p = 0.044). During follow-up, ΔLVMI was 3.9 g/m (− 10.7, 2.2) in GLU and 5.2 (− 26.8, 16.8) in ICO group (p = 0.651). ΔLVMI correlated with change in brain natriuretic peptide (r = 0.566, p = 0.044), which remained significant in a multiple regression analysis. The use of the icodextrin-based solution in prevalent patients on PD compared with a glucose-based solution was not able to improve LMV. A larger randomized trial with a longer follow-up period may be needed to show changes in LVM in this patient population. Trial registration: this study has been registered at ReBEC (Registro Brasileiro de Ensaios Clinicos) under the identification #RBR-2mzhmj2, available at: https://ensaiosclinicos.gov.br/pesquisador .

The present study employs high-level ab initio calculations to investigate the structure, vibrational frequencies, and electronic properties of H2S∙∙∙SO2. The analysis of vibrational frequencies reveals an intramolecular vibrational energy transfer phenomenon, where energy from the stretching modes of H2S is transferred to the ν1s mode of SO2. At the CCSD(T)/aug-cc-pVQZ level, the interaction energy between H2S and SO2 is predicted to be 2.78 kcal/mol. Electron propagator theory calculations yield a HOMO–LUMO gap of 8.24 eV for H2S∙∙∙SO2. Furthermore, by utilizing ab initio results for the adiabatic ionization energy and electron affinity, the electrophilicity of H2S∙∙∙SO2 is estimated to be 2.01 eV. This value is similar to the electrophilicity of SO2, suggesting comparable reactivity and chemical behavior. The non-covalent interaction (NCI) analysis of the H2S∙∙∙SO2 complex emphasizes the significant contribution of non-covalent van der Waals interactions in its energetic stabilization.

The present contribution proposes an optical method for the detection of glyphosate (GLY) using a Cu(II) bis-(oxamate) complex ([Cu(opba)]2−) as the fluorescent probe. It wa found that in acetonitrile solution, its fluorescence increases in the presence of GLY and scales linearly (R2 = 0.99) with GLY concentration in the range of 0.7 to 5.5 µM, which is far below that established by different international regulations. The probe is also selective to GLY in the presence of potential interferents, namely aminomethyl phosphonic acid and N-nitrosoglyphosate. Theoretical results obtained by time-dependent density functional theory coupled to a simplified treatment of the liquid environment by using a self-consistent reaction-field revealed that GLY molecules do not coordinate with the central Cu2+ ion of [Cu(opba)]2−; instead, they interact with its peripheral ligand through hydrogen bond formation. Thereby, GLY plays mainly the role of the proton donor. The results also suggest that GLY increases the dielectric constant of the medium when it contributes to the stabilization of the excited state of the [Cu(opba)]2− and enhancement of its fluorescence.

The success of the scan statistic in detecting anomalies in georeferenced data has motivated its use in distributed sensor systems to detect an emitter at an unknown location. Sensors are grouped into clusters, cluster statistics are produced, and the scan statistic decides that the emitter is present if any cluster statistic is above a threshold. Although the scan statistic is not the optimal fusion rule, it avoids combining strong measurements from sensors near the emitter with weak measurements from sensors far from the emitter. The question that motivates this paper is: could a clustering algorithm improve the detection performance of the scan statistic? Previous studies on the scan statistics considered that the set of clusters is given or is the product of a scanning process; and previous studies on clustering algorithms for wireless sensor networks have not considered forming clusters specifically for the scan statistic. Our first goal is to highlight the opportunity of improving the scan statistic by carefully designing the cluster set. We discuss how the cluster set influences not only the detection performance, but also processing and communication in the system. Our second goal is to propose and study a new clustering algorithm to build the cluster set for the scan statistic. Although suboptimal, our algorithm produces cluster sets that reach similar or better detection performance than the usually considered cluster sets with a significantly lower number of clusters, which results in less processing and communication in the system.

Background/Aims: Peritoneal dialysis (PD) has gained interest over the last decade as a viable option for early start dialysis. It is still unknown if shorter break-in periods and less time for proper patient evaluation and training could influence technique survival in comparison to planned-start PD. Methods: A prospective and observational study that compared technique survival in a cohort of patients who started either early or planned PD. Early start PD was defined as break-in period from 3 to 14 days with no previous nephrologist follow-up or patient training. Results: A total of 154 patients were included (40 as early start PD), followed by a median time of 381 days. Comparing early vs. planned-start PD, groups were similar concerning age 56 (40; 70) vs. 48 (32; 63) years, p=0.071, body mass index (BMI) 23.3 ± 4.2 vs. 23.8 ± 4.0 kg/m2, p=0.567 and male gender (60 vs. 48%, p=0.201), respectively. Comparing early vs. planned-start groups, there were no differences regarding PD dropout for peritonitis (7.5 vs. 11.4%, p=0.764), catheter dysfunction (12.5 vs. 17.5%, p=0.619) and patient burnout (0 vs. 4.4%, p=0.328), respectively. Less patients in early start group quit PD for peritoneal membrane failure in comparison to planned-start group (2.5 vs. 16.7%, p=0.026). In multivariate cox-regression analysis, the only factors independently associated with technique failure were BMI> 25 kg/m² (p=0.033) and Diabetes Mellitus (p=0.013), whereas no differences regarding early vs. planned-PD start were observed (p=0.184). Conclusion: Despite the adverse scenario for initiating dialysis, early start PD had similar outcomes in comparison to planned-start PD in long-term follow-up.

A 25-year-old patient was admitted to the emergency room presenting headaches after a traumatic brain injury (TBI) 30 days before, when he collided frontally with another driver. After a skull radiography, the presence of a foreign body was observed in the frontal sinus. A cranial computed tomography (CT) scan found that it was a tooth. The patient underwent surgical treatment for the removal of the tooth. Traumatic brain injury caused by non-missile penetrating objects is unusual, and has been described in case reports in the literature. To the best of our knowledge, no similar reports can be found in the literature.

Theoretical results for the magnetic shielding of protonated and unprotonated nitrogens of eumelanin building blocks including monomers, dimers, and tetramers in gas phase and water are presented. The magnetic property in water was determined by carrying out Monte Carlo statistical mechanics sampling combined with quantum mechanics calculations based on the gauge-including atomic orbitals approach. The results show that the environment polarization can have a marked effect on nitrogen magnetic shieldings, especially for the unprotonated nitrogens. Large contrasts of the oligomerization effect on magnetic shielding show a clear distinction between eumelanin building blocks in solution, which could be detected in nuclear magnetic resonance experiments. Calculations for a π-stacked structure defined by the dimer of a tetrameric building block indicate that unprotonated N atoms are significantly deshielded upon π stacking, whereas protonated N atoms are slightly shielded. The results stress the interest of NMR experiments for a better understanding of the eumelanin complex structure.

Background/Aims: Ultrafiltration that occurs during hemodialysis (HD) promotes profound alterations in a relatively short period of time. The dialysate content of bicarbonate (DBic) and potassium (DK) may have impact over intradialytic hemodynamics, which goes beyond ultrafiltration, and its impact was evaluated in a prospective cohort. Methods: 30 patients under HD were submitted to hemodynamic assessment (HA) at the beginning and at the end of HD sessions, through a non-invasive method. Serum minus dialysate potassium concentration was expressed as K-Gap. Cardiac index (CI) and peripheral arterial resistance (PAR) variation (post-HD minus pre-HD) were expressed as ΔCI and ΔPAR. Dialysate content of sodium and calcium were expressed as DNa and DCa, respectively. Results: Mean DNa, DK and DBic were, respectively, 136.4 ± 1.1, 2.1 ± 0.6 and 38.2 ± 2.1 mEq/L. In 15 patients, DCa was >1.5 mmol/L and in the other 15 patients ≤ 1.5 mmol/L. The K-Gap ranged from 1.4 to 5.1 mEq/l (median 3.0 mEq/L). There was a reduction in post-HD CI and systolic blood pressure (ΔCI = -0.72l/min/m2 and -11.3±15.1mmHg, respectively, p5, pConclusion: We confirmed that Na and Ca dialysate content exerts and important role on hemodynamic during HD. In addition, our findings pointed out that higher dialysate concentrations of bicarbonate and potassium promote lower cardiac performance at the end of hemodialysis session.

BACKGROUNDChronic kidney disease (CKD) affects 10-15% of adult population worldwide. Incident patients on hemodialysis, mainly those on urgent-start dialysis at the emergency room, have a high mortality risk, which may reflect the absence of nephrology care. A lack of data exists regarding the influence of baseline factors on the mortality of these patients. The aim of this study was to evaluate the clinical and laboratory characteristics of this population and identify risk factors that contribute to their mortality.PATIENTS AND METHODSWe studied 424 patients who were admitted to our service between 01/2006 and 12/2012 and were followed for 1 year. We analyzed vascular access, risk factors linked to cardiovascular disease (CVD) and mineral and bone disease associated with CKD (CKD-MBD), and clinical events that occurred during the follow-up period. Factors that influenced patient survival were evaluated by Cox regression analysis.RESULTSThe patient mean age was 50 ± 18 years, and 58.7% of them were male. Hypertension was the main cause of primary CKD (31.8%). Major risk factors were smoking (19.6%), dyslipidemia (48.8%), and CVD (41%). Upon admission, most patients had no vascular access for hemodialysis (89.4%). Biochemical results showed that most patients were anemic with high C-reactive protein levels, hypocalcemia, hyperphosphatemia, elevated parathyroid hormone and decreased 25-hydroxy vitamin D. At the end of one year, 60 patients died (14.1%). These patients were significantly older, had a lower percentage of arteriovenous fistula in one year, and low levels of 25-hydroxy vitamin D.CONCLUSIONSThe combined evaluation of clinical and biochemical parameters and risk factors revealed that the mortality in urgent-start dialysis is associated with older age and low levels of vitamin D deficiency. A lack of a permanent hemodialysis access after one year was also a risk factor for mortality in this population.

The electronic properties of SO2 at the surface of a water cluster were investigated by employing a combination of Born–Oppenheimer molecular dynamics and electron propagator theory (EPT). In our work, we utilized a revised version of the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional, which incorporates empirical corrections for dispersion interactions in line with a recent study of the air–water interface conducted by Ohto et al. [J. Phys. Chem. Lett. 10(17), 4914–4919 (2019)]. Polarization effects induce a significant broadening of the electron binding energy distribution, as predicted by EPT. This broadening can result in a substantial increase in electron affinity, impacting the chemical reactivity of SO2 at the air–water interface, a topic of significant and recent research interest. We discuss the relationship between electron binding energies (EBEs) and the specific connections of SO2 to water. The results indicate that configurations involving an OS⋯H bond tend to yield higher electron affinities compared to complex formation through S⋯OW bonds. Surprisingly, SO2 molecules not bound to water molecules according to a specific criterion may also exhibit higher electron affinities. This feature can be explained by the role played by the polarization field from water molecules. Our best estimate for the HOMO–LUMO (H–L) gap of SO2 at the surface of a water cluster is 11.6 eV. Very similar H–L gaps are predicted for isolated and micro-solvated SO2. Fukui functions for the gas phase, and the micro-solvated SO2–H2O complex supports the view that the LUMO is predominantly localized on the SO2 moiety. [ABSTRACT FROM AUTHOR]