Biominerals - source and inspiration for novel advanced materials

Biomineralization seems an odd sort of word. How can you combine biology and minerals? However, a quick look around brings to light many familiar objects that are examples of biominerals. Most dramatic are the coral reefs and sea shells of the marine environment (calcium carbonate) and human bone and teeth (calcium hydroxyapatite) but there are many other examples. In the past 10 years, an increasing number of biominerals has been reported (Table 1). Interest in the biological and chemical processes that lead to biomineralization, howeyer, has only developed rather recently. Early observations were made by paleontologists who were interested in the preservation, through geological time, of the hard parts of organisms such as shells and skeletons but only in 1989 did the field really come of age with the almost simultaneous publication of three monographs covering current knowledge of the biological, biochemical, chemical and taxonomic aspects of biomineralization (Mann et al. 1989; Lowenstam & Weiner 1989; Simkiss & Wilbur 1989)

Thinking intuitively: the rich (and at times illogical) world of concepts

Intuitive knowledge of the world involves knowing what kinds of things have which properties. We express it in generalities such as “ducks lay eggs”. It contrasts with extensional knowledge about actual individuals in the world, which we express in quantified statements such as “All US Presidents are male”. Reasoning based on this intuitive knowledge, while highly fluent and plausible may in fact lead us into logical fallacy. Several lines of research point to our conceptual memory as the source of this logical failure. We represent concepts with prototypical properties, judging likelihood and argument strength on the basis of similarity between ideas. Evidence that our minds represent the world in this intuitive way can be seen in a range of phenomena, including how people interpret logical connectives applied to everyday concepts, studies of creativity and emergence in conceptual combination, and demonstrations of the logically inconsistent beliefs that people express in their everyday language

Negations in syllogistic reasoning: Evidence for a heuristic–analytic conflict

An experiment utilizing response time measures was conducted to test dominant processing strategies in syllogistic reasoning with the expanded quantifier set proposed by Roberts (2005). Through adding negations to existing quantifiers it is possible to change problem surface features without altering logical validity. Biases based on surface features such as atmosphere, matching, and the probability heuristics model (PHM; Chater & Oaksford, 1999; Wetherick & Gilhooly, 1995) would not be expected to show variance in response latencies, but participant responses should be highly sensitive to changes in the surface features of the quantifiers. In contrast, according to analytic accounts such as mental models theory and mental logic (e.g., Johnson-Laird & Byrne, 1991; Rips, 1994) participants should exhibit increased response times for negated premises, but not be overly impacted upon by the surface features of the conclusion. Data indicated that the dominant response strategy was based on a matching heuristic, but also provided evidence of a resource-demanding analytic procedure for dealing with double negatives. The authors propose that dual-process theories offer a stronger account of these data whereby participants employ competing heuristic and analytic strategies and fall back on a heuristic response when analytic processing fails

Evidence for an Intermediate-mass Milky Way from Gaia DR2 Halo Globular Cluster Motions

We estimate the mass of the Milky Way (MW) within 21.1 kpc using the kinematics of halo globular clusters (GCs) determined by Gaia. The second Gaia data release (DR2) contained a catalogue of absolute proper motions (PMs) for a set of Galactic GCs and satellite galaxies measured using Gaia DR2 data. We select from the catalogue only halo GCs, identifying a total of 34 GCs spanning $2.0 < r < 21.1$ kpc, and use their 3D kinematics to estimate the anisotropy over this range to be $\beta = 0.46^{+0.15}_{-0.19}$, in good agreement, though slightly lower than, a recent estimate for a sample of halo GCs using HST PM measurements further out in the halo. We then use the Gaia kinematics to estimate the mass of the MW inside the outermost GC to be $M(< 21.1 \mathrm{kpc}) = 0.21^{+0.04}_{-0.03} 10^{12} \mathrm{M_\odot}$, which corresponds to a circular velocity of $v_\mathrm{circ}(21.1 \mathrm{kpc}) = 206^{+19}_{-16}$ km/s. The implied virial mass is $M_\mathrm{virial} = 1.28^{+0.97}_{-0.48} 10^{12} \mathrm{M_\odot}$. The error bars encompass the uncertainties on the anisotropy and on the density profile of the MW dark halo, and the scatter inherent in the mass estimator we use. We get improved estimates when we combine the Gaia and HST samples to provide kinematics for 46 GCs out to 39.5 kpc: $\beta = 0.52^{+0.11}_{-0.14}$, $M(< 39.5 \mathrm{kpc}) = 0.42^{+0.07}_{-0.06} 10^{12} \mathrm{M_\odot}$, and $M_\mathrm{virial} = 1.54^{+0.75}_{-0.44} 10^{12} \mathrm{M_\odot}$. We show that these results are robust to potential substructure in the halo GC distribution. While a wide range of MW virial masses have been advocated in the literature, from below $10^{12} \mathrm{M_\odot}$ to above $2 \times 10^{12}\mathrm{M_\odot}$, these new data imply that an intermediate mass is most likely

ent-Clerodane Diterpenes from the Bark of Croton oligandrus Pierre ex. Hutch. and Assessment of their Cytotoxicity Against Human Cancer Cell Lines

New clerodane diterpenes, 12-epi-megalocarpodolide D (2) and an epimeric mixture of crotonolins A (3) and B (4), were isolated from the bark of Croton oligandrus following a bioassay-guided isolation protocol. Known compounds, megalocarpodolide D (1), 12-epi-crotocorylifuran (5), cluytyl-ferulate (6), hexacosanoyl- ferulate (7), vanillin (8), acetyl-aleuritolic acid (9) and lupeol (10), were also isolated. The structures of the isolated compounds (1-10) were elucidated by spectroscopic means. The cytotoxicity of compounds 1-10 was assessed against A549, MCF7, PC3 and PNT2 cell lines using the MTT assay. Compounds 1 and 2 showed moderate level of activity against both A549 and MCF7 cells with 1 being the most active with IC50 values of 63.8±13.8 and 136.2±22.7 µM against A549 and MCF7 cells, respectively. The epimeric mixture of 3 and 4 was moderately active against A549 and PC3 cells (IC50 = 128.6±31.0 and 111.2±2.9 µM, respectively)

The role of scenario, deontic conditionals and problem content in Wason´s selection task

This paper was presented at "The European Conference on Cognitive Science. Siena, Italy, October 1999"This experiment explores the influence of thematic content, the presence or absence of a scenario and the use of deontic or indicative framing of conditional rules on performance on Wason’s selection task. Logical performance was affected by the content used (permission rules were the best, neutral the worst and obligation rules intermediate) and by the use of scenarios. The scenario effect interacted significantly with the problem framing such that the presence of a scenario facilitate performance only when problems were framed in a deontic rather than indicative manner. The presence of scenarios did not interact with the problem content. These results are discussed in terms of pragmatic influences on reasoning, within the framework of the Dual Process Theory (Evans & Over, 1996

Study of Forces During Ultrasonic Vibration Assisted Grinding

AbstractRadial and tangential grinding forces were presented as four components connected with workpiece material microcutting and plastic deformation, and friction of cutting and abrasive grains (AGs) with the workpiece.The depth of abrasive grain penetration in the workpiece and the cutting width are determined with regard to ultrasonic vibrations (USV) amplitude and frequency. Summing up of the forces from single grains was conducted by using a multiple integral, provided that one of the integration limits is a function describing change of the depth of the AGs penetration in the workpiece material which depends on the USV parameters. Dependencies were obtained for calculation of all grinding force components at different vibration amplitudes and frequencies when various number of USV waves fits the contact arc of the grain and the workpiece.Experimental values of grinding forces turned out to be 10 – 15% lower than those when USV waves are not applied

A dual process account of creative thinking

This article explicates the potential role played by type 1 thinking (automatic, fast) and type 2 thinking (effortful, logical) in creative thinking. The relevance of Evans's (2007) models of conflict of dual processes in thinking is discussed with regards to creative thinking. The role played by type 1 thinking and type 2 thinking during the different stages of creativity (problem finding and conceptualization, incubation, illumination, verification and dissemination) is discussed. It is proposed that although both types of thinking are active in creativity, the extent to which they are active and the nature of their contribution to creativity will vary between stages of the creative process. Directions for future research to test this proposal are outlined; differing methodologies and the investigation of different stages of creative thinking are discussed. © Taylor & Francis Group, LLC

Assumption-free estimation of the genetic contribution to refractive error across childhood

Purpose: Studies in relatives have generally yielded high heritability estimates for refractive error: twins 75–90%, families 15–70%. However, because related individuals often share a common environment, these estimates are inflated (via misallocation of unique/common environment variance). We calculated a lower-bound heritability estimate for refractive error free from such bias. Methods: Between the ages 7 and 15 years, participants in the Avon Longitudinal Study of Parents and Children (ALSPAC) underwent non-cycloplegic autorefraction at regular research clinics. At each age, an estimate of the variance in refractive error explained by single nucleotide polymorphism (SNP) genetic variants was calculated using genome-wide complex trait analysis (GCTA) using high-density genome-wide SNP genotype information (minimum N at each age=3,404). Results: The variance in refractive error explained by the SNPs (“SNP heritability”) was stable over childhood: Across age 7–15 years, SNP heritability averaged 0.28 (SE=0.08,