Influence of crystallographic orientation of biogenic calcite on <i>in situ</i> Mg XANES analyses

Micro X-ray absorption near-edge spectroscopy at the Mg &lt;i&gt;K&lt;/i&gt;-edge is a useful technique for acquiring information about the environment of Mg&lt;sup&gt;2+&lt;/sup&gt; in biogenic calcite. These analyses can be applied to shell powders or intact shell structures. The advantage of the latter is that the XANES analyses can be applied to specific areas, at high (e.g. micrometre) spatial resolution, to determine the environment of Mg&lt;sup&gt;2+&lt;/sup&gt; in a biomineral context. Such in situ synchrotron analysis has to take into account the potential effect of crystallographic orientation given the anisotropy of calcite crystals and the polarized nature of X-rays. Brachiopod shells of species with different crystallographic orientations are used to assess this crystallographic effect on &lt;i&gt;in situ&lt;/i&gt; synchrotron measurements at the Mg &lt;i&gt;K&lt;/i&gt;-edge. Results show that, owing to the anisotropy of calcite, &lt;i&gt;in situ&lt;/i&gt; X-ray absorption spectra (XAS) are influenced by the crystallographic orientation of calcite crystals with a subsequent potentially erroneous interpretation of Mg&lt;sup&gt;2+&lt;/sup&gt; data. Thus, this study demonstrates the importance of crystallography for XAS analyses and, therefore, the necessity to obtain crystallographic information at high spatial resolution prior to spectroscopic analysis

Assessment of crystallographic influence on material properties of calcite brachiopods

Calcium carbonate biominerals are frequently analysed in materials science due to their abundance, diversity and unique material properties. Aragonite nacre is intensively studied, but less information is available about the material properties of biogenic calcite, despite its occurrence in a wide range of structures in different organisms. In particular, there is insufficient knowledge about how preferential crystallographic orientations influence these material properties. Here, we study the influence of crystallography on material properties in calcite semi-nacre and fibres of brachiopod shells using nano-indentation and electron backscatter diffraction (EBSD). The nano-indentation results show that calcite semi-nacre is a harder and stiffer (H {approx} 3–5 GPa; E = 50–85 GPa) biomineral structure than calcite fibres (H = 0.4–3 GPa; E = 30–60 GPa). The integration of EBSD to these studies has revealed a relationship between the crystallography and material properties at high spatial resolution for calcite semi-nacre. The presence of crystals with the c-axis perpendicular to the plane-of-view in longitudinal section increases hardness and stiffness. The present study determines how nano-indentation and EBSD can be combined to provide a detailed understanding of biomineral structures and their analysis for application in materials science

Control of crystal polymorph in microfluidics using molluscan 28 kDa Ca2+-binding protein

Biominerals produced by biological systems in physiologically relevant environments possess extraordinary properties that are often difficult to replicate under laboratory conditions. Understanding the mechanism that underlies the process of biomineralisation can lead to novel strategies in the development of advanced materials. Using microfluidics, we have demonstrated for the first time, that an extrapallial (EP) 28 kDa protein, located in the extrapallial compartment between mantle and shell of Mytilus edulis, can influence, at both micro- and nanoscopic levels, the morphology, structure and polymorph that is laid down in the shell ultrastructure. Crucially, this influence is predominantly dependent on the existence of an EP protein concentration gradient and its consecutive interaction with Ca2+ ions. Novel lemon-shaped hollow vaterite structures with a clearly defined nanogranular assembly occur only where particular EP protein and Ca2+ gradients co-exist. Computational fluid dynamics enabled the progress of the reaction to be mapped and the influence of concentration gradients across the device to be calculated. Importantly, these findings could not have been observed using conventional bulk mixing methods. Our findings not only provide direct experimental evidence of the potential influence of EP proteins in crystal formation, but also offer a new biomimetic strategy to develop functional biomaterials for applications such as encapsulation and drug delivery

Does Size Matter in the Field?: Female Police Bodies in Online Television

The purpose of this study is to investigate how female officers’ body sizes are depicted on the TV show, “Police Women of Broward County.” Little literature examines the media’s depiction of bodies belonging to women who are involved in traditionally masculine professions. However, feminist and masculinist literature, along with biophysical literature, tends to suggest that women are smaller and weaker than men or are perceived that way in society. It stands to reason that media may portray female officers this way or portray women attempting to overcome this stigma personally and professionally to appeal to viewers or as a reflection of mainstream attitudes or ideas. Using a record-review case study methodology, the researcher examined free snippets and numerous online episodes of the TLC Network show, “Police Women of Broward County.” The show, which includes fieldwork and interviews, contained quotations about size, and scenarios in which size appeared to be relevant to policing. Overcoming the stigma was a recurring theme, but it was not the only theme. Some comments were positively associated with female officers’ sizes insofar as police seemed tenaciously motivated by their smaller stature. However, some comments that connected size, gender, and professionalism seemed to be negative or to suggest diminution. Some comments discussed size differences within the female police population but the comments were neither negative nor positive because they were merely factual or informational

The ACIGA Data Analysis programme

The Data Analysis programme of the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) was set up in 1998 by the first author to complement the then existing ACIGA programmes working on suspension systems, lasers and optics, and detector configurations. The ACIGA Data Analysis programme continues to contribute significantly in the field; we present an overview of our activities.Comment: 10 pages, 0 figures, accepted, Classical and Quantum Gravity, (Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 2003

Variability of aerosol optical properties in the Western Mediterranean Basin

Aerosol light scattering, absorption and particulate matter (PM) concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB) which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR). Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm) were 26.6±23.2 Mm&lt;sup&gt;−1&lt;/sup&gt; and 4.3±2.7 Mm&lt;sup&gt;−1&lt;/sup&gt;, respectively and the mean aerosol absorption coefficient (@ 637 nm) was 2.8±2.2 Mm&lt;sup&gt;−1&lt;/sup&gt;. Mean values of Single Scattering Albedo (SSA) and Ångström exponent (&lt;i&gt;å&lt;/i&gt;) (calculated from 450 nm to 635 nm) at MSY were 0.90±0.05 and 1.3±0.5 respectively. A clear relationship was observed between the PM&lt;sub&gt;1&lt;/sub&gt;/PM&lt;sub&gt;10&lt;/sub&gt; and PM&lt;sub&gt;2.5&lt;/sub&gt;/PM&lt;sub&gt;10&lt;/sub&gt; ratios as a function of the calculated Ångström exponents. Mass scattering cross sections (MSC) for fine mass and sulfate at 635 nm were 2.8±0.5 m&lt;sup&gt;2&lt;/sup&gt; g&lt;sup&gt;−1&lt;/sup&gt; and 11.8±2.2 m&lt;sup&gt;2&lt;/sup&gt; g&lt;sup&gt;−1&lt;/sup&gt;, respectively, while the mean aerosol absorption cross section (MAC) was 10.4±2.0 m&lt;sup&gt;2&lt;/sup&gt; g&lt;sup&gt;−1&lt;/sup&gt;. The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The MAC values appear dependent of particles aging: similar to the expected absorption cross-section for fresh emissions under Atlantic Advection episodes and higher under aerosol pollution episodes. The analysis of the Ångström exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (&lt;i&gt;å&lt;/i&gt; = 1.5±0.1) while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly dominated by coarser particles (&lt;i&gt;å&lt;/i&gt; = 1.0±0.4). The sea breeze played an important role in transporting pollutants from the developed WMB coastlines towards inland rural areas, changing the optical properties of aerosols. Aerosol scattering and backscattering coefficients increased by around 40 % in the afternoon when the sea breeze was fully developed while the absorption coefficient increased by more than 100 % as a consequence of the increase in the equivalent black carbon concentration (EBC) observed at MSY under sea breeze circulation

An information theoretic characterisation of auditory encoding.

The entropy metric derived from information theory provides a means to quantify the amount of information transmitted in acoustic streams like speech or music. By systematically varying the entropy of pitch sequences, we sought brain areas where neural activity and energetic demands increase as a function of entropy. Such a relationship is predicted to occur in an efficient encoding mechanism that uses less computational resource when less information is present in the signal: we specifically tested the hypothesis that such a relationship is present in the planum temporale (PT). In two convergent functional MRI studies, we demonstrated this relationship in PT for encoding, while furthermore showing that a distributed fronto-parietal network for retrieval of acoustic information is independent of entropy. The results establish PT as an efficient neural engine that demands less computational resource to encode redundant signals than those with high information content

Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

No abstract available

Alpha-fetoprotein detection of hepatocellular carcinoma leads to a standardized analysis of dynamic AFP to improve screening based detection

Detection of hepatocellular carcinoma (HCC) through screening can improve outcomes. However, HCC surveillance remains costly, cumbersome and suboptimal. We tested whether and how serum Alpha-Fetoprotein (AFP) should be used in HCC surveillance. Record linkage, dedicated pathways for management and AFP data-storage identified i) consecutive highly characterised cases of HCC diagnosed in 2009–14 and ii) a cohort of ongoing HCC-free patients undergoing regular HCC surveillance from 2009. These two well-defined Scottish patient cohorts enabled us to test the utility of AFP surveillance. Of 304 cases of HCC diagnosed over 6 years, 42% (129) were identified by a dedicated HCC surveillance programme. Of these 129, 47% (61) had a detectable lesion first identified by screening ultrasound (US) but 38% (49) were prompted by elevated AFP. Despite pre-HCC diagnosis AFP &gt;20kU/L being associated with poor outcome, ‘AFP-detected’ tumours were offered potentially curative management as frequently as ‘US-detected’ HCCs; and had comparable survival. Linearity of serial log10-transformed AFPs in HCC cases and in the screening ‘HCC-free’ cohort (n = 1509) provided indicators of high-risk AFP behaviour in HCC cases. An algorithm was devised in static mode, then tested dynamically. A case/control series in hepatitis C related disease demonstrated highly significant detection (p&lt;1.72*10−5) of patients at high risk of developing HCC. These data support the use of AFP in HCC surveillance. We show proof-of-principle that an automated and further refine-able algorithmic interpretation of AFP can identify patients at higher risk of HCC. This approach could provide a cost-effective, user-friendly and much needed addition to US surveillance

Quantum atomic delocalization vs. structural disorder in amorphous silicon

Quantum effects on the atom delocalization in amorphous silicon have been studied by path-integral Monte Carlo simulations from 30 to 800 K. The quantum delocalization is appreciable vs. topological disorder, as seen from structural observables such as the radial distribution function (RDF). At low temperatures, the width of the first peak in the RDF increases by a factor of 1.5 due to quantum effects. The overall anharmonicity of the solid vibrations at finite temperatures in amorphous silicon is clearly larger than in the crystalline material. Low-energy vibrational modes are mainly located on coordination defects in the amorphous material.Comment: 5 pages, 5 PS figures, REVTE