The effects of electromagnetic fields on the detection of mercury and radionuclides

Mercury and many radionuclides are extremely toxic, and their monitoring and detection are of importance for human health and environmental protection. This dissertation focuses on the detection of mercury (II) ions and radionuclides including uranium (234U and 238U), plutonium (239Pu), and americium (241Am) in aqueous solutions under the effects of electromagnetic fields. The stripping electrochemical method has been widely used to detect mercury (II) ions in aqueous solutions. To enhance the detection sensitivity of the conventional electrochemical method, mechanically stirring the solution is usually performed to enhance the rate of the ionic mass transport. Instead of mechanically stirring the solution; the electrochemical cell is positioned in a magnetic field provided by permanent magnets. The interaction between the current density transmitted through the solution and the magnetic field induces Lorentz force, thus magneto-hydrodynamic (MHD) flow, which can be used to stir and mix the sample solution uniformly without the use of any mechanical moving parts or rotating electrodes; This research develops an ultra sensitive mercury sensor by integrating the MHD with the electrochemical analyzer, and with the surface plasmon resonance (SPR) instrument, and its detection limit is obtained down to 1 ppb. To improve the resolution of the alpha spectrum during the detection of 234U, 238U, 239Pu, and 241Am, hydrous oxides of the radionuclides were electrochemically deposited onto the surface of a steel planchet in the presence of a magnetic field. The steel planchet was then washed and dried, and the energy spectrum emitted was measured with the alpha spectrometer. A homogeneous and thin film with larger grain size was formed during the deposition step due to the induced MHD flow leading to a higher resolution in the detection sensitivity and the alpha spectrum

Impact of climate change on phenology of Rhododendron arboreum Sm., Myrica esculenta Buch.­Ham. ex D. Don and Alnus nepalensis D. Don

This study was objectively carried out to show the trend of climatic variables to determine the effect of climatic variables on seasons and assess the response of phenology of a tree rhododendron Rhododendron arboreum Sm., kaphal Myrica esculenta Buch.­Ham. ex D. Don and the Nepalese alder Alnus nepalensis D. Don at Bakte, Devithan and Nagarkot forests of Kavreplanchok district, Nepal. Climatic data such as rainfall and temperature from 1947 to 2016, were collected. Maps of selected sites were prepared and stratified into tree rhododendron, kaphal and Nepalese alder block. Altogether 60 samples having 10 × 10 m were collected from different directions (South, North, East and West). The diameter and height of seedlings were recorded and temperature was registered between February 18 to March 15, 2018. The total of 50 households was surveyed to get familiar with the ideas about climate change and its impacts on phenology. The result showed the highest average annual temperature around 17.41 °C in 2012, while rainfall was recorded highest about 2345.5 mm in 1985. The estimated highest monsoon temperature was 22.61 °C in 2012 and the lowest 8.93 °C in winter 1997. The (1947–2016) winter rainfall shows increasing by 0.05 mm but monsoon rainfall is decreasing by 2.99 mm annually. Direct measurements of temperature for 26 days showed the highest 26.5 °C on March 14 and the lowest 21.8 °C in February 18, 2018. The highest number of flowers of tree rhododendron and kaphal was found in southern aspect. The flowering started 15–30 days earlier its normal date, which was also confirmed by local people. Height growth of seedlings of tree rhododendron was 1.5 cm at southern aspect. This research will be useful for science community and policy makers

The effect of unbalanced demographic structure on marriage and feritlity patterns in isolated populations: the case of Viking settlements in Greenland.

Can the decline of a small and isolated population occur as a consequence of a random imbalance in the sex ratio at birth and/or in the male/female mortality rates in subsequent age groups? We should stress here the use of the term “random”. Indeed, the imbalance we refer to is what occurs in a small population as the ultimate result of pure chance. This hypothesis (of the imbalance of the sex ratio) was studied in particular by the Italian statistician Corrado Gini (1957), although it had previously been put forward by other authors (Livi 1941, 1944). More specifically, Gini explained the extinction of the medieval settlements in Greenland using this hypothesis.The recent publication of Lynnerup’s book (1998) concerning the demography of these settlements, based on the archaeological evidence of skeletal remains, prompted us to re-evaluate Gini’s treatise. We wanted to give a statistical contribution – using a Bayesian inference – to evaluate Gini’s hypothesis of that extinction. The extinction of the settlements in Greenland is widely regarded as “almost an enigma hinting at some inexplicable and dramatic event veiled by the passage of time” (Lynnerup1998, p. 8).The aim of this paper is therefore to check Gini’s hypothesis from a Bayesian point of view. In this scheme, the prior distribution is the probability of an imbalance in the sex ratio occurring in the history of a small and closed population as a result of random and unfavourable alterations of the sex-ratio at birth and at death. In order to evaluate such a probability, a Monte Carlo technique that uses historical, demographic and biometric constants (Livi Bacci 1998) will be outlined. The posterior probability is then updated in the light of some archaeological data

Tracking Target Signal Strengths on a Grid using Sparsity

Multi-target tracking is mainly challenged by the nonlinearity present in the measurement equation, and the difficulty in fast and accurate data association. To overcome these challenges, the present paper introduces a grid-based model in which the state captures target signal strengths on a known spatial grid (TSSG). This model leads to \emph{linear} state and measurement equations, which bypass data association and can afford state estimation via sparsity-aware Kalman filtering (KF). Leveraging the grid-induced sparsity of the novel model, two types of sparsity-cognizant TSSG-KF trackers are developed: one effects sparsity through $\ell_1$-norm regularization, and the other invokes sparsity as an extra measurement. Iterative extended KF and Gauss-Newton algorithms are developed for reduced-complexity tracking, along with accurate error covariance updates for assessing performance of the resultant sparsity-aware state estimators. Based on TSSG state estimates, more informative target position and track estimates can be obtained in a follow-up step, ensuring that track association and position estimation errors do not propagate back into TSSG state estimates. The novel TSSG trackers do not require knowing the number of targets or their signal strengths, and exhibit considerably lower complexity than the benchmark hidden Markov model filter, especially for a large number of targets. Numerical simulations demonstrate that sparsity-cognizant trackers enjoy improved root mean-square error performance at reduced complexity when compared to their sparsity-agnostic counterparts.Comment: Submitted to IEEE Trans. on Signal Processin

A DedA Family Membrane Protein Is Required for Burkholderia thailandensis Colistin Resistance

© Copyright © 2019 Panta, Kumar, Stafford, Billiot, Douglass, Herrera, Trent and Doerrler. Colistin is a “last resort” antibiotic for treatment of infections caused by some multidrug resistant Gram-negative bacterial pathogens. Resistance to colistin varies between bacterial species. Some Gram-negative bacteria such as Burkholderia spp. are intrinsically resistant to very high levels of colistin with minimal inhibitory concentrations (MIC) often above 0.5 mg/ml. We have previously shown DedA family proteins YqjA and YghB are conserved membrane transporters required for alkaline tolerance and resistance to several classes of dyes and antibiotics in Escherichia coli. Here, we show that a DedA family protein in Burkholderia thailandensis (DbcA; DedA of Burkholderia required for colistin resistance) is a membrane transporter required for resistance to colistin. Mutation of dbcA results in \u3e100-fold greater sensitivity to colistin. Colistin resistance is often conferred via covalent modification of lipopolysaccharide (LPS) lipid A. Mass spectrometry of lipid A of ΔdbcA showed a sharp reduction of aminoarabinose in lipid A compared to wild type. Complementation of colistin sensitivity of B. thailandensis ΔdbcA was observed by expression of dbcA, E. coli yghB or E. coli yqjA. Many proton-dependent transporters possess charged amino acids in transmembrane domains that take part in the transport mechanism and are essential for function. Site directed mutagenesis of conserved and predicted membrane embedded charged amino acids suggest that DbcA functions as a proton-dependent transporter. Direct measurement of membrane potential shows that B. thailandensis ΔdbcA is partially depolarized suggesting that loss of protonmotive force can lead to alterations in LPS structure and severe colistin sensitivity in this species

Development of a clinical prediction model for the onset of functional decline in people aged 65-75 years: Pooled analysis of four European cohort studies

Background: Identifying those people at increased risk of early functional decline in activities of daily living (ADL) is essential for initiating preventive interventions. The aim of this study is to develop and validate a clinical prediction model for onset of functional decline in ADL in three years of follow-up in older people of 65-75 years old. Methods: Four population-based cohort studies were pooled for the analysis: ActiFE-ULM (Germany), ELSA (United Kingdom), InCHIANTI (Italy), LASA (Netherlands). Included participants were 65-75 years old at baseline and reported no limitations in functional ability in ADL at baseline. Functional decline was assessed with two items on basic ADL and three items on instrumental ADL. Participants who reported at least some limitations at three-year follow-up on any of the five items were classified as experiencing functional decline. Multiple logistic regression analysis was used to develop a prediction model, with subsequent bootstrapping for optimism-correction. We applied internal-external cross-validation by alternating the data from the four cohort studies to assess the discrimination and calibration across the cohorts. Results: Two thousand five hundred sixty community-dwelling people were included in the analyses (mean age 69.7 ± 3.0 years old, 47.4% female) of whom 572 (22.3%) reported functional decline at three-year follow-up. The final prediction model included 10 out of 22 predictors: age, handgrip strength, gait speed, five-repeated chair stands time (non-linear association), body mass index, cardiovascular disease, diabetes, chronic obstructive pulmonary disease, arthritis, and depressive symptoms. The optimism-corrected model showed good discrimination with a C statistic of 0.72. The calibration intercept was 0.06 and the calibration slope was 1.05. Internal-external cross-validation showed consistent performance of the model across the four cohorts. Conclusions: Based on pooled cohort data analyses we were able to show that the onset of functional decline in ADL in three years in older people aged 65-75 years can be predicted by specific physical performance measures, age, body mass index, presence of depressive symptoms, and chronic conditions. The prediction model showed good discrimination and calibration, which remained stable across the four cohorts, supporting external validity of our findings

Dry eye in systemic sclerosis patients: Novel methods to monitor disease activity

Background: In systemic sclerosis (SSc) patients, dry eye syndrome (DES) is the most frequent ocular feature. The aim of this study was to investigate ocular DES-related SSc patients and to establish any correlation with the severity of the disease. Methods: Retrospectively, data from 60 patients with SSc underwent ophthalmic examination, where non-invasive film tear break-up time (NIF-TBUT), tear film lipid layer thickness (LLT), anesthetic-free Schirmer test I, tear osmolarity measurement (TearLab System), and modified Rodnan skin score (mRSS) data were collected. The visual analog scale (VAS) and Symptom Assessment in Dry Eye (SANDE) methods were utilized. The results were correlated with mRSS and the duration of SSc. Results: Severe DES occurred in 84% of cases, and was more severe in women. The eyelids were involved in 86.6%, secondary to meibomian gland disease (MGD). A direct correlation was found between the tear osmolarity (mean 328.51 ± 23.8 SD) and skin score (mRSS) (r = 0.79; p < 0.01). Significantly reduced NIF-TBUT, LLT, and Schirmer test I values were observed in the case of severe skin involvement. Conclusions: SSc patients show lipid tear dysfunction related to the severity and duration of the disease due to inflammation and the subsequent atrophy of the meibomian glands