Nonlinear growth generates age changes in the moments of the frequency distribution: the example of height in puberty

Higher moments of the frequency distribution of child height and weight change with age, particularly during puberty, though why is not known. Our aims were to confirm that height skewness and kurtosis change with age during puberty, to devise a model to explain why, and to test the model by analyzing the data longitudinally. Heights of 3245 Christ's Hospital School boys born during 1927-1956 were measured twice termly from 9 to 20 years (n = 129 508). Treating the data as independent, the mean, standard deviation (SD), skewness, and kurtosis were calculated in 40 age groups and plotted as functions of age t. The data were also analyzed longitudinally using the nonlinear random-effects growth model H( t) = h( t - epsilon) + alpha, with H( t) the cross-sectional data, h( t) the individual mean curve, and epsilon and alpha subject-specific random effects reflecting variability in age and height at peak height velocity (PHV). Mean height increased monotonically with age, while the SD, skewness, and kurtosis changed cyclically with, respectively, 1, 2, and 3 turning points. Surprisingly, their age curves corresponded closely in shape to the first, second, and third derivatives of the mean height curve. The growth model expanded as a Taylor series in e predicted such a pattern, and the longitudinal analysis showed that adjusting for age at PHV on a multiplicative scale largely removed the trends in the higher moments. A nonlinear growth process where subjects grow at different rates, such as in puberty, generates cyclical changes in the higher moments of the frequency distribution

Bayesian astrostatistics: a backward look to the future

This perspective chapter briefly surveys: (1) past growth in the use of Bayesian methods in astrophysics; (2) current misconceptions about both frequentist and Bayesian statistical inference that hinder wider adoption of Bayesian methods by astronomers; and (3) multilevel (hierarchical) Bayesian modeling as a major future direction for research in Bayesian astrostatistics, exemplified in part by presentations at the first ISI invited session on astrostatistics, commemorated in this volume. It closes with an intentionally provocative recommendation for astronomical survey data reporting, motivated by the multilevel Bayesian perspective on modeling cosmic populations: that astronomers cease producing catalogs of estimated fluxes and other source properties from surveys. Instead, summaries of likelihood functions (or marginal likelihood functions) for source properties should be reported (not posterior probability density functions), including nontrivial summaries (not simply upper limits) for candidate objects that do not pass traditional detection thresholds.Comment: 27 pp, 4 figures. A lightly revised version of a chapter in "Astrostatistical Challenges for the New Astronomy" (Joseph M. Hilbe, ed., Springer, New York, forthcoming in 2012), the inaugural volume for the Springer Series in Astrostatistics. Version 2 has minor clarifications and an additional referenc

The impact of power clean ability and training age on adaptations to weightlifting-style training

The purpose of this investigation was to determine whether weightlifting actions are a viable method for improving athletic performance amongst weaker, inexperienced lifters when compared to individuals with a greater power clean result, and hence weightlifting ability and experience. Two groups of males with distinctly different power clean performances (higher performance (HP): N = 8; BM = 78.1±4.0 kg; 1RM PC = 1.08±0.09 kg.BM-1; lower performance (LP): N = 8; BM=82.6±14.0 kg; 1RM PC=0.78±0.1 kg⸱BM-1) and resistance training age (HP: resistance training experience=3.5±1.2 years; LP: resistance training experience=1.44±1.50 years) undertook 10 weeks of training involving weightlifting derivatives, in addition to supplemental ballistic and plyometric exercises. Testing of athletic performance (represented by measures derived from the countermovement jump) occurred at baseline, after five weeks of training, and after ten weeks of training. Both groups significantly improved across the majority of outcome variables following training (Hedges g=0.98–2.55, P≤0.01-0.05). Only the HP participants experienced significant changes at mid-test (g = 0.99–1.27, P ≤ 0.01-0.05), while no significant changes were revealed between mid- and post-test in this group. In contrast to this, the LP participants displayed a significant improvement in relative impulse (g=1.39, P<0.01) and rate of force development (g=1.91, P<0.01) during this final period (P<0.01). As weaker, inexperienced lifters underwent a significant and meaningful enhancement in maximal neuromuscular measures following weightlifting derivative focused training, practitioners should consider early implementation of such exercises. However, it is important for coaches to note that a delayed training effect might be present in weaker, less experienced lifters

The vegetation history of an Amazonian domed peatland

The peatland pole forests of the Pastaza-Marañón Foreland Basin (PMFB), Peru, are the most carbon-dense ecosystems known in Amazonia once below ground carbon stores are taken into account. Here we present the first multiproxy palaeoenvironmental record including pollen data from one of these peatlands, San Jorge in northern Peru, supported by an age model based on radiocarbon and 210Pb dating. The pollen data indicate that vegetation changes during the early phases of peat initiation resulted from autogenic succession in combination with fluvial influence. The overall pattern of vegetation change is not straightforward: the record does not reflect a process of unidirectional, progressive terrestrialization, but includes a reversal in the succession and vegetation transitions, which omit predicted successional phases. This complexity is similar to that seen in the only other existing pollen record from a PMFB peatland, at Quistococha, but contrasts with peat records from Panama and Southeast Asia where successional patterning appears more predictable. Our dating results provide the first evidence from a PMFB peatland that peat accumulation may have been discontinuous, with evidence for reduced rates of peat accumulation, or a possible hiatus, around 1300–400 cal yr BP. An ecological shift from open lake to palm swamp occurs at this time, possibly driven by climatic change. The pollen data indicate that the present pole forest vegetation at San Jorge began to assemble c. 200–150 cal yr BP. Given this young age, it is likely that the pole forest at this site remains in a state of transition

The Effects of Previous Error and Success in Alzheimer’s Disease and Mild Cognitive Impairment

This work investigated in Alzheimer’s disease dementia (AD), whether the probability of making an error on a task (or a correct response) was influenced by the outcome of the previous trials. We used the antisaccade task (AST) as a model task given the emerging consensus that it provides a promising sensitive and early biological test of cognitive impairment in AD. It can be employed equally well in healthy young and old adults, and in clinical populations. This study examined eye-movements in a sample of 202 participants (42 with dementia due to AD; 65 with mild cognitive impairment (MCI); 95 control participants). The findings revealed an overall increase in the frequency of AST errors in AD and MCI compared to the control group, as predicted. The errors on the current trial increased in proportion to the number of consecutive errors on the previous trials. Interestingly, the probability of errors was reduced on the trials that followed a previously corrected error, compared to the trials where the error remained uncorrected, revealing a level of adaptive control in participants with MCI or AD dementia. There was an earlier peak in the AST distribution of the saccadic reaction times for the inhibitory errors in comparison to the correct saccades. These findings revealed that the inhibitory errors of the past have a negative effect on the future performance of healthy adults as well as people with a neurodegenerative cognitive impairment

Ozone’s Impact on Public Health: Contributions from Indoor Exposures to Ozone and Products of Ozone-Initiated Chemistry

OBJECTIVE: The associations between ozone concentrations measured outdoors and both morbidity and mortality may be partially due to indoor exposures to ozone and ozone-initiated oxidation products. In this article I examine the contributions of such indoor exposures to overall ozone-related health effects by extensive review of the literature as well as further analyses of published data. FINDINGS: Daily inhalation intakes of indoor ozone (micrograms per day) are estimated to be between 25 and 60% of total daily ozone intake. This is especially noteworthy in light of recent work indicating little, if any, threshold for ozone’s impact on mortality. Additionally, the present study estimates that average daily indoor intakes of ozone oxidation products are roughly one-third to twice the indoor inhalation intake of ozone alone. Some of these oxidation products are known or suspected to adversely affect human health (e.g., formaldehyde, acrolein, hydroperoxides, fine and ultrafine particles). Indirect evidence supports connections between morbidity/mortality and exposures to indoor ozone and its oxidation products. For example, cities with stronger associations between outdoor ozone and mortality tend to have residences that are older and less likely to have central air conditioning, which implies greater transport of ozone from outdoors to indoors. CONCLUSIONS: Indoor exposures to ozone and its oxidation products can be reduced by filtering ozone from ventilation air and limiting the indoor use of products and materials whose emissions react with ozone. Such steps might be especially valuable in schools, hospitals, and childcare centers in regions that routinely experience elevated outdoor ozone concentrations

FEMA GRAS assessment of natural flavor complexes: Sage oil, Orris Root Extract and Tagetes Oil and related flavoring ingredients

In recent years, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) has conducted a program to re-evaluate the safety of natural flavor complexes (NFCs) used as flavor ingredients. This publication, twelfth in the series, details the re-evaluation of NFCs whose constituent profiles are characterized by alicyclic or linear ketones. In its re-evaluation, the Expert Panel applies a scientific constituent-based procedure for the safety evaluation of NFCs in commerce using a congeneric group approach. Estimated intakes of each congeneric group of the NFC are evaluated using the well-established and conservative Threshold of Toxicological Concern (TTC) approach. In addition, studies on the toxicity and genotoxicity of members of the congeneric groups and the NFCs under evaluation are reviewed. The scope of the safety evaluation of the NFCs contained herein does not include added use in dietary supplements or any products other than food. Thirteen (13) NFCs derived from the Boronia, Cinnamomum, Thuja, Ruta, Salvia, Tagetes, Hyssopus, Iris, Perilla and Artemisia genera are affirmed as generally recognized as safe (GRAS) under conditions of their intended use as flavor ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein

Associations between food group intakes and circulating insulin-like growth factor-I in the UK Biobank: a cross-sectional analysis

PURPOSE: Circulating insulin-like growth factor-I (IGF-I) concentrations have been positively associated with risk of several common cancers and inversely associated with risk of bone fractures. Intakes of some foods have been associated with increased circulating IGF-I concentrations; however, evidence remains inconclusive. Our aim was to assess cross-sectional associations of food group intakes with circulating IGF-I concentrations in the UK Biobank. METHODS: At recruitment, the UK Biobank participants reported their intake of commonly consumed foods. From these questions, intakes of total vegetables, fresh fruit, red meat, processed meat, poultry, oily fish, non-oily fish, and cheese were estimated. Serum IGF-I concentrations were measured in blood samples collected at recruitment. After exclusions, a total of 438,453 participants were included in this study. Multivariable linear regression was used to assess the associations of food group intakes with circulating IGF-I concentrations. RESULTS: Compared to never consumers, participants who reported consuming oily fish or non-oily fish ≥ 2 times/week had 1.25 nmol/L (95% confidence interval:1.19–1.31) and 1.16 nmol/L (1.08–1.24) higher IGF-I concentrations, respectively. Participants who reported consuming poultry ≥ 2 times/week had 0.87 nmol/L (0.80–0.94) higher IGF-I concentrations than those who reported never consuming poultry. There were no strong associations between other food groups and IGF-I concentrations. CONCLUSIONS: We found positive associations between oily and non-oily fish intake and circulating IGF-I concentrations. A weaker positive association of IGF-I with poultry intake was also observed. Further research is needed to understand the mechanisms which might explain these associations

Membrane Interactions and Uncoating of Aichi Virus, a Picornavirus That Lacks a VP4.

Kobuviruses are an unusual and poorly characterized genus within the picornavirus family and can cause gastrointestinal enteric disease in humans, livestock, and pets. The human kobuvirus Aichi virus (AiV) can cause severe gastroenteritis and deaths in children below the age of 5 years; however, this is a very rare occurrence. During the assembly of most picornaviruses (e.g., poliovirus, rhinovirus, and foot-and-mouth disease virus), the capsid precursor protein VP0 is cleaved into VP4 and VP2. However, kobuviruses retain an uncleaved VP0. From studies with other picornaviruses, it is known that VP4 performs the essential function of pore formation in membranes, which facilitates transfer of the viral genome across the endosomal membrane and into the cytoplasm for replication. Here, we employ genome exposure and membrane interaction assays to demonstrate that pH plays a critical role in AiV uncoating and membrane interactions. We demonstrate that incubation at low pH alters the exposure of hydrophobic residues within the capsid, enhances genome exposure, and enhances permeabilization of model membranes. Furthermore, using peptides we demonstrate that the N terminus of VP0 mediates membrane pore formation in model membranes, indicating that this plays an analogous function to VP4. IMPORTANCE To initiate infection, viruses must enter a host cell and deliver their genome into the appropriate location. The picornavirus family of small nonenveloped RNA viruses includes significant human and animal pathogens and is also a model to understand the process of cell entry. Most picornavirus capsids contain the internal protein VP4, generated from cleavage of a VP0 precursor. During entry, VP4 is released from the capsid. In enteroviruses this forms a membrane pore, which facilitates genome release into the cytoplasm. Due to high levels of sequence similarity, it is expected to play the same role for other picornaviruses. Some picornaviruses, such as Aichi virus, retain an intact VP0, and it is unknown how these viruses rearrange their capsids and induce membrane permeability in the absence of VP4. Here, we have used Aichi virus as a model VP0 virus to test for conservation of function between VP0 and VP4. This could enhance understanding of pore function and lead to development of novel therapeutic agents that block entry

Visual parameter optimisation for biomedical image processing

Background: Biomedical image processing methods require users to optimise input parameters to ensure high quality output. This presents two challenges. First, it is difficult to optimise multiple input parameters for multiple input images. Second, it is difficult to achieve an understanding of underlying algorithms, in particular, relationships between input and output. Results: We present a visualisation method that transforms users’ ability to understand algorithm behaviour by integrating input and output, and by supporting exploration of their relationships. We discuss its application to a colour deconvolution technique for stained histology images and show how it enabled a domain expert to identify suitable parameter values for the deconvolution of two types of images, and metrics to quantify deconvolution performance. It also enabled a breakthrough in understanding by invalidating an underlying assumption about the algorithm. Conclusions: The visualisation method presented here provides analysis capability for multiple inputs and outputs in biomedical image processing that is not supported by previous analysis software. The analysis supported by our method is not feasible with conventional trial-and-error approaches