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If an industrial civilization had existed on Earth many millions of years prior to our own era, what traces would it have left and would they be detectable today? We summarize the likely geological fingerprint of the Anthropocene, and demonstrate that while clear, it will not differ greatly in many respects from other known events in the geological record. We then propose tests that could plausibly distinguish an industrial cause from an otherwise naturally occurring climate event.
The lengthy and complex focal article by Tett, Hundley, and Christiansen (2017) is based on a fundamental misunderstanding of the nature of validity generalization (VG): It is based on the assumption that what is generalized in VG is the estimated value of mean rho (
). This erroneous assumption is stated repeatedly throughout the article. A conclusion of validity generalization does not imply that
is identical across all situations. If VG is present, most, if not all, validities in the validity distribution are positive and useful even if there is some variation in that distribution. What is generalized is the entire distribution of rho (
), not just the estimated
or any other specific value of validity included in the distribution. This distribution is described by its mean (
) and standard deviation (SDρ). A helpful concept based on these parameters (assuming ρ is normally distributed) is the credibility interval, which reflects the range where most of the values of ρ can be found. The lower end of the 80% credibility interval (the 90% credibility value, CV =
– 1.28 × SDρ) is used to facilitate understanding of this distribution by indicating the statistical “worst case” for validity, for practitioners using VG. Validity has an estimated 90% chance of lying above this value. This concept has long been recognized in the literature (see Hunter & Hunter, 1984, for an example; see also Schmidt, Law, Hunter, Rothstein, Pearlman, & McDaniel, 1993, and hundreds of VG articles that have appeared in the literature over the past 40 years since the invention of psychometric meta-analysis as a means of examining VG [Schmidt & Hunter, 1977]). The
is the value in the distribution with the highest likelihood of occurring (although often by only a small amount), but it is the whole distribution that is generalized. Tett et al. (2017) state that some meta-analysis articles claim that they are generalizing only
. If true, this is inappropriate. Because
has the highest likelihood in the ρ distribution, discussion often focuses on that value as a matter of convenience, but
is not what is generalized in VG. What is generalized is the conclusion that there is validity throughout the credibility interval. The false assumption that it is
and not the ρ distribution as a whole that is generalized in VG is the basis for the Tett et al. article and is its Achilles heel. In this commentary, we examine the target article's basic arguments and point out errors and omissions that led Tett et al. to falsely conclude that VG is a “myth.”
We present first results of a new heterodyne spectrometer dedicated to high-resolution spectroscopy of molecules of astrophysical importance. The spectrometer, based on a room-temperature heterodyne receiver, is sensitive to frequencies between 75 and 110 GHz with an instantaneous bandwidth of currently 2.5 GHz in a single sideband. The system performance, in particular the sensitivity and stability, is evaluated. Proof of concept of this spectrometer is demonstrated by recording the emission spectrum of methyl cyanide, CH3CN. Compared to state-of-the-art radio telescope receivers the instrument is less sensitive by about one order of magnitude. Nevertheless, the capability for absolute intensity measurements can be exploited in various experiments, in particular for the interpretation of the ever richer spectra in the ALMA era. The ease of operation at room-temperature allows for long time integration, the fast response time for integration in chirped pulse instruments or for recording time dependent signals. Future prospects as well as limitations of the receiver for the spectroscopy of complex organic molecules (COMs) are discussed.
In this commentary, we build on Bracken, Rose, and Church's (2016) definition stating that 360° feedback should involve “the analysis of meaningful comparisons of rater perceptions across multiple ratees, between specific groups of raters” (p. 764). Bracken et al. expand on this component of the definition later by stressing that “the ability to conduct meaningful comparisons of rater perceptions both between (inter) and within (intra) groups is central and, indeed, unique to any true 360° feedback process” (p. 767; italicized in their focal article). Bracken et al. stress that “This element of our definition acknowledges that 360° feedback data represent rater perceptions that may contradict each other while each being true and valid observations” (p. 767).
Previous studies have suggested that prenatal maternal folate deficiency is associated with reduced prenatal brain growth and psychological problems in offspring. However, little is known about the longer-term impact. The aims of this study were to investigate whether prenatal maternal folate insufficiency, high total homocysteine levels and low vitamin B12 levels are associated with altered brain morphology, cognitive and/or psychological problems in school-aged children. This study was embedded in Generation R, a prospective population-based cohort study. The study sample consisted of 256 Dutch children aged between 6 and 8 years from whom structural brain scans were collected using MRI. The mothers of sixty-two children had insufficient (<8 nmol/l) plasma folate concentrations in early pregnancy. Cognitive development was assessed by the Snijders-Oomen Niet-verbale intelligentietest – Revisie and the NEPSY-II-NL. Psychological problems were assessed at age 6 years using the parent report of the Child Behavior Checklist. Low prenatal folate levels were associated with a smaller total brain volume (B –33·34; 95 % CI –66·7, 0·02; P=050) and predicted poorer performance on the language (B –0·28; 95 % CI –0·52, –0·04; P=0·020) and visuo-spatial domains (B –0·27; 95 % CI –0·50, –0·04; P=0·021). High homocysteine levels (>9·1 µmol/l) predicted poorer performance on the language (B –0·31; 95 % CI –0·56, –0·06; P=0·014) and visuo-spatial domains (B –0·36; 95 % CI –0·60, –0·11; P=0·004). No associations with psychological problems were found. Our findings suggest that folate insufficiency in early pregnancy has a long-lasting, global effect on brain development and is, together with homocysteine levels, associated with poorer cognitive performance.
In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing a direct parameter extraction methodology dedicated to III–V based HBTs. It is shown that the modeling of measured S-parameters can be improved in the millimeter-wave frequency range by augmenting the small-signal model with a description of AC current crowding. The extracted elements of the small-signal model structure are employed as a starting point for the extraction of a large-signal model. The developed large-signal model for the TS-HBTs accurately predicts the DC over temperature and small-signal performance over bias as well as the large-signal performance at millimeter-wave frequencies.
Rigorous finite element optical simulations have been used to examine the absorption of light in various crystalline silicon based, nanostructured solar cell architectures. The compared structures can all be produced on glass substrates using a periodically structured dielectric coating and a combination of electron-beam evaporation of silicon and subsequent solid phase crystallization. A required post-treatment by selective etching of non-compact silicon regions results in an absorber material loss. We show that by adequately tailoring the optical design around the processed silicon layer, the absorptance loss due to material removal can be completely overcome. The resulting silicon structure, which is an array of holes with non-vertical sidewalls, shows promising light path enhancement and features an even higher absorptance than the initial nanodome structure of the unetched absorber.
Our focus is on the difficulties that synthetic validity encounters in attempting to achieve discriminant validity and the implications of these difficulties. Johnson et al. (2010) acknowledge the potential problems involved in attaining discriminant validity in synthetic validity. For example, they report that Peterson et al. (2001), Johnson (2007), and other synthetic validity studies report failure to achieve discriminant validity. What this failure means is that a synthetic validity equation developed to predict validity for Job A does as well in predicting validity for Jobs B, C, D, and so forth as it does for Job A. Johnson et al. then go on to propose that this problem might be overcome by careful attention to both the criterion and predictor sides of synthetic validity. We question whether their proposals can be made to work.
La réunion des chefs de délégations et des délégués régionaux du CICR qui s'est tenue à Glion, du 19 au 22 janvier 1997, a été un événement pour l'institution. Elle a perrais de mobiliser les cadres opérationnels sur les questions de sécurité dans les situations où se déploie l'action humanitaire. Les tragédies récentes qui avaient frappé le CICR (assassinat de dix collaborateurs au Burundi, en Tchétchénie et au Cambodge), ainsi que le meurtre qui venait d'être commis au Rwanda, de trois collaborateurs de Médecins du monde et de quatre de l'ONU, ont souligné l'urgente nécessité de réévaluer les mesures de sécurité et les modalités d'intervention humanitaire en faveur des victimes des conflits.
Previous European guidance for environmental risk assessment of genetically
modified plants emphasized the concepts of statistical power but provided no
explicit requirements for the provision of statistical power analyses.
Similarly, whilst the need for good experimental designs was stressed, no
minimum guidelines were set for replication or sample sizes. Furthermore,
although substantial equivalence was stressed as central to risk assessment,
no means of quantification of this concept was given. This paper suggests
several ways in which existing guidance might be revised to address these
problems. One approach explored is the `bioequivalence' test, which has the
advantage that the error of most concern to the consumer may be set
relatively easily. Also, since the burden of proof is placed on the
experimenter, the test promotes high-quality, well-replicated experiments
with sufficient statistical power.
Other recommendations cover the specification of effect sizes, the choice of
appropriate comparators, the use of positive controls, meta-analyses,
multivariate analysis and diversity indices. Specific guidance is suggested
for experimental designs of field trials and their statistical analyses. A
checklist for experimental design is proposed to accompany all environmental
Membrane proteins comprise the majority of known and potential drug targets, yet have been immensely difficult to analyze at the structural level due to their location in the membrane bilayer. Removal from the membrane necessitates replacement of the phospholipid bilayer by detergents in order to maintain protein solubility. However, the absence of lipids and the presence of detergents can render non-physiological conformational changes of the membrane protein (Tate, 2006). Electron crystallography is an important method for studying membrane proteins that usually takes advantage of reconstituting the protein in a phospholipid bilayer and removal of the detergent. Richard Henderson and Nigel Unwin used this technique to elucidate the three-dimensional (3D) arrangement of the transmembrane α-helices of bacteriorhodopsin, which was the first 3D structural information on a membrane protein (Henderson and Unwin, 1975).