On the analysis of signal peaks in pulse-height spectra

The estimation of the signal location and intensity of a peak in a pulse height spectrum is important for X-ray and γ-ray spectroscopy, charged-particle spectrometry, liquid chromatography, and many other subfields. However, both the “centroid” and “signal intensity” of a peak in a pulse-height spectrum are ill-defined quantities and different methods of analysis will yield different numerical results. Here, we apply three methods of analysis. Method A is based on simple count summation and is likely the technique most frequently applied in practice. The analysis is straightforward and fast, and does not involve any statistical modeling. We find that it provides reliable results only for high signal-to-noise data, but has severe limitations in all other cases. Method B employs a Bayesian model to extract signal counts and centroid from the measured total and background counts. The resulting values are derived from the respective posteriors and, therefore, have a rigorous statistical meaning. The method makes no assumptions about the peak shape. It yields reliable and relatively small centroid uncertainties. However, it provides relatively large signal count uncertainties. Method C makes a strong assumption regarding the peak shape by fitting a Gaussian function to the data. The fit is based again on a Bayesian model. Although Method C requires careful consideration of the Gaussian width (usually given by the detector resolution) used in the fitting, it provides reliable values and relatively small uncertainties both for the signal counts and the centroid

Maternal periconceptional and first trimester protein restriction in beef heifers: effects on maternal performance and early fetal growth

This study evaluated the effect of protein restriction during the periconception (PERI) and first trimester (POST) periods on maternal performance, physiology and early fetal growth. Yearling nulliparous heifers (n = 360) were individually fed a diet high or low in protein (HPeri and LPeri respectively) beginning 60 days before conception. From 24 to 98 days post-conception (dpc), half of each treatment group changed to the alternative post-conception high- or low-protein diet (HPost and LPost respectively), yielding four groups in a 2 × 2 factorial design with a common diet until parturition. Protein restriction was associated with lower bodyweight subsequent to reduced (but positive) average daily weight gain (ADG) during the PERI and POST periods. During the POST period, ADG was greater in LPeri than HPeri heifers and tended to be greater in LPost than HPost heifers during the second and third trimester. Bodyweight was similar at term. The pregnancy rate did not differ, but embryo loss between 23 and 36 dpc tended to be greater in LPeri than HPeri heifers. Overall, a greater proportion of male fetuses was detected (at 60 dpc 63.3% male vs 36.7% female). Protein restriction altered maternal plasma urea, non-esterified fatty acids, progesterone, leptin and insulin-like growth factor 1 at critical stages of fetal development. However, profiles varied depending on the sex of the conceptus.Katrina J. Copping, Andrew Hoare, I. Caroline McMillen, Raymond J. Rodgers, Charles R. Wallace and Viv E.A. Perr

What is the Oxygen Isotope Composition of Venus? The Scientific Case for Sample Return from Earth’s “Sister” Planet

Venus is Earth’s closest planetary neighbour and both bodies are of similar size and mass. As a consequence, Venus is often described as Earth’s sister planet. But the two worlds have followed very different evolutionary paths, with Earth having benign surface conditions, whereas Venus has a surface temperature of 464 °C and a surface pressure of 92 bar. These inhospitable surface conditions may partially explain why there has been such a dearth of space missions to Venus in recent years.The oxygen isotope composition of Venus is currently unknown. However, this single measurement (Δ17O) would have first order implications for our understanding of how large terrestrial planets are built. Recent isotopic studies indicate that the Solar System is bimodal in composition, divided into a carbonaceous chondrite (CC) group and a non-carbonaceous (NC) group. The CC group probably originated in the outer Solar System and the NC group in the inner Solar System. Venus comprises 41% by mass of the inner Solar System compared to 50% for Earth and only 5% for Mars. Models for building large terrestrial planets, such as Earth and Venus, would be significantly improved by a determination of the Δ17O composition of a returned sample from Venus. This measurement would help constrain the extent of early inner Solar System isotopic homogenisation and help to identify whether the feeding zones of the terrestrial planets were narrow or wide.Determining the Δ17O composition of Venus would also have significant implications for our understanding of how the Moon formed. Recent lunar formation models invoke a high energy impact between the proto-Earth and an inner Solar System-derived impactor body, Theia. The close isotopic similarity between the Earth and Moon is explained by these models as being a consequence of high-temperature, post-impact mixing. However, if Earth and Venus proved to be isotopic clones with respect to Δ17O, this would favour the classic, lower energy, giant impact scenario.We review the surface geology of Venus with the aim of identifying potential terrains that could be targeted by a robotic sample return mission. While the potentially ancient tessera terrains would be of great scientific interest, the need to minimise the influence of venusian weathering favours the sampling of young basaltic plains. In terms of a nominal sample mass, 10 g would be sufficient to undertake a full range of geochemical, isotopic and dating studies. However, it is important that additional material is collected as a legacy sample. As a consequence, a returned sample mass of at least 100 g should be recovered.Two scenarios for robotic sample return missions from Venus are presented, based on previous mission proposals. The most cost effective approach involves a “Grab and Go” strategy, either using a lander and separate orbiter, or possibly just a stand-alone lander. Sample return could also be achieved as part of a more ambitious, extended mission to study the venusian atmosphere. In both scenarios it is critical to obtain a surface atmospheric sample to define the extent of atmosphere-lithosphere oxygen isotopic disequilibrium. Surface sampling would be carried out by multiple techniques (drill, scoop, “vacuum-cleaner” device) to ensure success. Surface operations would take no longer than one hour.Analysis of returned samples would provide a firm basis for assessing similarities and differences between the evolution of Venus, Earth, Mars and smaller bodies such as Vesta. The Solar System provides an important case study in how two almost identical bodies, Earth and Venus, could have had such a divergent evolution. Finally, Venus, with its runaway greenhouse atmosphere, may provide data relevant to the understanding of similar less extreme processes on Earth. Venus is Earth’s planetary twin and deserves to be better studied and understood. In a wider context, analysis of returned samples from Venus would provide data relevant to the study of exoplanetary systems

An investigation into the psychometric properties of the Hospital Anxiety and Depression Scale in individuals with chronic fatigue syndrome

The study sought to determine the psychometric properties of the Hospital Anxiety and Depression Scale (HADS) in individuals with chronic fatigue syndrome (GFS) assessed using a web-based data collection tool. Exploratory and confirmatory factor analyses were conducted on the HADS to determine its psychometric properties in 117 individuals with CFS. Seven models were tested to determine model fit to the data. Internal reliability estimations of the anxiety and depression sub-scales were found to be acceptable, however, a three-factor model was found to provide a significantly better fit to the data when compared to the bi-dimensional two-factor structure previously assumed to underpin the HADS' construct validity. The clinical utility of the HADS in the assessment of anxiety and depression in CFS appears to be fundamentally compromised by the presence of a three-dimensional underlying factor structure. Future revision of the HADS is recommended if the instrument is to be used reliably to screen CFS patients

The influence of body weight and body composition information on initial exercise motivation in female exercise initiates with overweight and obesity

The study purpose was to examine the impact of providing individualized body composition information (intervention condition; n = 40) versus body weight information (standard control condition; n = 40) on motivational regulations in overweight female exercise initiates about to commence an exercise program. The Behavioral Regulation in Exercise Questionnaire-2 was completed prior to and following the information provision. Results revealed a significant increase in introjected regulation for the intervention condition indicating that the body composition information may have reinforced previous feelings of self-imposed pressure and a sense of obligation to start exercising. Implications for motivating new exercisers are discussed

Person-centered/experiential psychotherapy for anxiety difficulties : theory, research and practice

Anxiety difficulties are an increasingly important focus for person-centered/experiential (PCE) psychotherapies. I begin by reviewing person-centered, focusing-oriented, and emotion-focused therapy (EFT) theories of anxiety. Next, I summarize a meta-analysis of 19 outcome studies of PCE therapies for adults with anxiety, most commonly supportive or person-centered therapies (PCT) carried out by cognitive behavior therapy (CBT) researchers. The results indicate large pre-post change but a clear inferiority to CBT. I then summarize promising early results from an ongoing study of PCT and EFT for social anxiety, which show large amounts of pre-post change for both forms of PCE therapy but substantially more change for clients in the EFT condition. I conclude with a discussion of the implications for PCE therapy practice, including the value of process differentiation and the possibility of developing more effective PCE approaches for anxiety