Parametric power spectral density analysis of noise from instrumentation in MALDI TOF mass spectrometry

Noise in mass spectrometry can interfere with identification of the biochemical substances in the sample. For example, the electric motors and circuits inside the mass spectrometer or in nearby equipment generate random noise that may distort the true shape of mass spectra. This paper presents a stochastic signal processing approach to analyzing noise from electrical noise sources (i.e., noise from instrumentation) in MALDI TOF mass spectrometry. Noise from instrumentation was hypothesized to be a mixture of thermal noise, 1/f noise, and electric or magnetic interference in the instrument. Parametric power spectral density estimation was conducted to derive the power distribution of noise from instrumentation with respect to frequencies. As expected, the experimental results show that noise from instrumentation contains 1/f noise and prominent periodic components in addition to thermal noise. These periodic components imply that the mass spectrometers used in this study may not be completely shielded from the internal or external electrical noise sources. However, according to a simulation study of human plasma mass spectra, noise from instrumentation does not seem to affect mass spectra significantly. In conclusion, analysis of noise from instrumentation using stochastic signal processing here provides an intuitive perspective on how to quantify noise in mass spectrometry through spectral modeling

Behandeling en stigmamanagement bij opzettelijke zelfverwonding: het smalle pad tussen te veel en te weinig interveniëren

Opzettelijke zelfverwonding wordt gedefinieerd als de intentionele directe beschadiging van het eigen lichaam, zonder bewuste suïcidale intentie. De behandeling varieert van gedwongen opname in een psychiatrische instelling (in het Britse Gemenebest), tot een permissieve aanpak zonder behandeling en uiteenlopende behandelingsmogelijkheden er tussenin. Eerst wordt de gepastheid van de mate van interveniëren besproken in functie van verschillende diagnosen. Het tweede gedeelte van het artikel bespreekt het advies dat door hulpverleners verstrekt wordt aangaande de omgang met wonden en littekens en aangaande de mogelijkheden voor een (gewezen) zelfverwonder om het stigma van een deviante identiteit te vermijden. Een rondvraag bij Belgische hulpverleners bracht aan het licht dat velen onder hen adviseren om littekens te verbergen, terwijl er anderzijds aanwijzingen zijn dat niet-verbergen een teken van herstel is. Aangezien verbergen en smoesjes verzinnen ook kunnen leiden tot de instandhouding van een deviante identiteit, wordt gewezen op meer gepaste vormen van stigmamanagement

A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5-22.7) and 16.5 cm (13.3-19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8-144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities 1,2 . This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity 3�6 . Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 of the global rise in mean BMI from 1985 to 2017�and more than 80 in some low- and middle-income regions�was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing�and in some countries reversal�of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories. © 2019, The Author(s)

A Machine Learning Application for Classification of Chemical Spectra

This paper presents a software package that allows chemists to analyze spectroscopy data using innovative machine learning (ML) techniques. The package, designed for use in conjunction with lab-based spectroscopic instruments, includes features to encourage its adoption by analytical chemists, such as having an intuitive graphical user interface with a step-by-step `wizard¿ for building new ML models, supporting standard file types and data preprocessing, and incorporating well-known standard chemometric analysis techniques as well as new ML techniques for analysis of spectra, so that users can compare their performance. The ML techniques that were developed for this application have been designed based on considerations of the defining characteristics of this problem domain, and combine high accuracy with visualization, so that users are provided with some insight into the basis for classification decisions

Controlled-release melatonin implants delay puberty in rats without altering melatonin rhythmicity

There is increasing evidence that continuous availability of melatonin via implants can produce the same physiological changes in animals as timed administration of the hormone. The mechanisms underlying this apparent contradiction are not known. In an attempt to gain further understanding of the way continuous melatonin administration affects reproductive activity, the effects of melatonin implants on gonadal development and melatonin production were investigated in rats treated neonatally with testosterone. Five-day-old male rats maintained on a 12L:12D photoperiod were injected with 1 mg testosterone propionate to induce photo-responsiveness and implanted at 21 days of age with novel melatonin implants designed to raise the daytime blood melatonin concentration into the nighttime range, i.e., from less than 60 pM in the controls during the day to 380 +/- 33 pM in the implanted rats. Following 21 days treatment, seminal vesicle and ventral prostate weights of implanted rats were significantly less than the controls (27.0 +/- 1.9 vs. 18.5 +/- 1.5 mg/ 100 g BW (P = 0.003) and 33.8 +/- 2.1 vs. 26.7 +/- 2.2 mg/100 g BW (P = 0.02), respectively). To determine the effect of the implants upon melatonin production, urine was collected at hourly intervals during the last four days of the experiment and the hourly 6-sulphatoxymelatonin (aMT.6S) excretion rate was determined. Rats bearing melatonin implants maintained a rhythm of aMT.6S excretion in 12L:12D, which was indistinguishable from that in the control animals except for a raised daytime excretion of the metabolite. Following one cycle of urinary aMT.6S measurements in the light/dark cycle, the animals were released into constant darkness, with the implants still in place or after their removal four hours before darkness to evaluate the characteristics of the melatonin rhythm in the absence of masking effects of the light/dark cycle. The melatonin rhythm persisted in both control and implanted rats and no differences in the onset, offset, or amplitude could be determined. The results of this study indicate that, like many other mammals, for laboratory rats controlled continuous release of melatonin can mimic the effects of short daylength or timed melatonin administration. Despite the reproductive consequences of continuous melatonin delivery, the timing of endogenous melatonin production is unaffected