Gene expression profiling of cuticular proteins across the moult cycle of the crab Portunus pelagicus

Background: Crustaceans represent an attractive model to study biomineralization and cuticle matrix formation, as these events are precisely timed to occur at certain stages of the moult cycle. Moulting, the process by which crustaceans shed their exoskeleton, involves the partial breakdown of the old exoskeleton and the synthesis of a new cuticle. This cuticle is subdivided into layers, some of which become calcified while others remain uncalcified. The cuticle matrix consists of many different proteins that confer the physical properties, such as pliability, of the exoskeleton

Synthesis of anisotropic 3D nanomagnets for magnetic actuation and sensing in piezoelectric polyvinylidene fluoride towards magnetic nanogenerator device fabrication

The 3D geometry and anisotropic properties of magnetic nanostructures has been found to have a direct impact on their magnetization properties due to spatial coordinates and larger surface areas, which sheds new light on next-generation materials for advanced applications in magnetic energy harvesting. Our work presents novel pathways for the synthesis and assembly of multifunctional anisotropic 3D nanomagnets with various shapes and sizes with key attention to their anisotropic morphologies. We investigated the excellent properties of these new anisotropic 3D nanomagnets for the design of magnetic actuator systems and nanogenerators by embedding the 3D nanomagnets in a piezoelectric polyvinylidene fluoride (PVDF) polymer matrix. The 3D nanomagnets-PDVF composites were found to exhibit the highly electroactive β-phase with enhanced piezoelectric sensitivity. Further, the 3D nanomagnets-PDVF thin films have outstanding magnetic responsiveness and actuation capacity ideal for the fabrication of magnetic nanogenerators. These types of materials have a great deal of potential to generate sustainable alternative energy sources through harvesting and conversion of ubiquitous and residual low-frequency environmental magnetic noise into usable electricity

Synthesis of anisotropic 3D nanomagnets for magnetic actuation and sensing in piezoelectric polyvinylidene fluoride towards magnetic nanogenerator device fabrication

The 3D geometry and anisotropic properties of magnetic nanostructures has been found to have a direct impact on their magnetization properties due to spatial coordinates and larger surface areas, which sheds new light on next-generation materials for advanced applications in magnetic energy harvesting. Our work presents novel pathways for the synthesis and assembly of multifunctional anisotropic 3D nanomagnets with various shapes and sizes with key attention to their anisotropic morphologies. We investigated the excellent properties of these new anisotropic 3D nanomagnets for the design of magnetic actuator systems and nanogenerators by embedding the 3D nanomagnets in a piezoelectric polyvinylidene fluoride (PVDF) polymer matrix. The 3D nanomagnets-PDVF composites were found to exhibit the highly electroactive β-phase with enhanced piezoelectric sensitivity. Further, the 3D nanomagnets-PDVF thin films have outstanding magnetic responsiveness and actuation capacity ideal for the fabrication of magnetic nanogenerators. These types of materials have a great deal of potential to generate sustainable alternative energy sources through harvesting and conversion of ubiquitous and residual low-frequency environmental magnetic noise into usable electricity

Applying the Power of Transcriptomics: Understanding Male Sexual Development in Decapod Crustacea

The decapod Crustacea are the most species-rich order of the Crustacea and include some of the most charismatic and highly valued commercial species. Thus the decapods draw a significant research interest in relation to aquaculture, as well as gaining a broader understanding of these species’ biology. However, the diverse physiology of the group considered with the lack of a model species have presented an obstacle for comparative analyses. In reflection of this, the recent integration of comparative transcriptomics has rapidly advanced our understanding of key regulatory pathways and developmental phenomena, an example being our understanding of sexual development. We discuss our work in the Eastern spiny lobster, Sagmariasus verreauxi, in the context of what is currently known about male sexual development in the decapods, highlighting the importance of transcriptomic techniques in achieving our recent advancements. We describe the progression made in our understanding of male sexual differentiation and maturation, as mediated by the insulin-like androgenic gland hormone (IAG), integrating the role of regulatory binding proteins (IGFBPs), a tyrosine kinase insulin receptor (TKIR), as well as the upstream effect of neuroendocrine hormones (GIH and MIH). We then consider the less well understood mechanism of male sex determination, with an emphasis on what we believe to be the key regulatory factors, the Dsx- and mab-3-related transcription factors (Dmrts). Finally, we discuss the function of the antennal gland (AnG) in sexual development, relating to the emergence of male-biased upregulation in the AnG in later sexual maturation and the sexually dimorphic expression of two key genes Sv-TKIR and Sv-Dmrt1. We then present the AnG as a case study to illustrate how comparative transcriptomic techniques can be applied to guide preliminary analyses, like the hypothesis that the AnG may function in pheromone biosynthesis. In summary, we describe the power of transcriptomics in facilitating the progress made in our understanding of male sexual development, as illustrated by the commercial decapod species, S. verreauxi. Considering future directions, we suggest that the integration of multiple omics-based techniques offers the most powerful tool to ensure we continue to piece together the biology of the important group of decapod Crustacea

Touching Random Surfaces and Liouville Gravity

Large $N$ matrix models modified by terms of the form g(\Tr\Phi^n)^2 generate random surfaces which touch at isolated points. Matrix model results indicate that, as $g$ is increased to a special value $g_t$, the string susceptibility exponent suddenly jumps from its conventional value $\gamma$ to ${\gamma\over\gamma-1}$. We study this effect in \L\ gravity and attribute it to a change of the interaction term from $O e^{\alpha_+ \phi}$ for $g<g_t$ to $O e^{\alpha_- \phi}$ for $g=g_t$ ($\alpha_+$ and $\alpha_-$ are the two roots of the conformal invariance condition for the \L\ dressing of a matter operator $O$). Thus, the new critical behavior is explained by the unconventional branch of \L\ dressing in the action.Comment: 15 pages, PUPT-1486 (last paragraph of sec. 2 revised

Green synthesis of carbon dots using expired agar for a label-free fluorescence signal-amplified detection of ferric ion utilizing oxalate functionalization

Surface passivation strategies for functional carbon-based nanoparticles can provide unrivalled performance whilst fine-tuning their optical properties in addition to giving routes for large-scale syntheses. Herein, the synthesis of highly fluorescent agar-derived and oxalate-functionalized carbon dots (ag-oxCDs) is presented. We deployed a facile hydrothermal protocol, using expired potato dextrose agar and oxalate as “green” precursors to prepare fluorescent ag-oxCDs with a relative fluorescence (FL) quantum yield of ∼32% (emission/excitation wavelengths: 445/340 nm). The switchable fluorescence properties of the prepared ag-oxCDs was used for developing a sensitive nanosensor for ferric ion [Fe(III)] detection. Through Fe(III) coordination to the oxalate passivated surface of ag-oxCDs, the FL of ag-oxCDs was enhanced by an aggregation-induced emission enhancement mechanism. The tested and optimized concentration of Fe(III) was within a broad linear range of 0.5–1500 μM, with a detection limit of 75 nM (s/N = 3). The practical application of the ag-oxCDs-based FL nanosensor for real-time quantitative monitoring of Fe(III) was demonstrated by detecting up to 0.15 μM of Fe(III) in spiked human serum and water samples

Transfer of negative valence in an episodic memory task

Emotion can color what we perceive and subsequently remember in myriad ways. Indeed, it is well established that emotion enhances some aspects of memory, while impairing others. For example, a number of recent episodic memory studies show that emotion—particularly negative emotion—weakens associative memory, including item-item associations. Other literature shows that emotion biases our later attitudes and preferences. That is, the coincident pairing of a negative stimulus with a neutral one can reduce one's preference for that neutral stimulus upon subsequent encounter—a ‘transfer of valence’ effect. In an effort to connect these two phenomena, here we ask if and under what circumstances they co-occur. Across multiple experiments, we show that negative emotion impairs associative memory for item-item pairings, in accordance with prior work. We also show a transfer of valence effect in this paradigm, such that items paired with negative versus neutral stimuli are subsequently rated as less pleasant. Our data further show that transfer of valence is contingent on episodic memory. These findings highlight the complexity and multifaceted nature of emotional effects on memory

The forbidden high ionisation line region of the type 2 quasar Q1131+16: a clear view of the inner face of the torus?

We present spectroscopic observations of the type 2 quasar SDSS J11311.05+162739.5 (Q1131+16 hereafter; z=0.1732), which has the richest spectrum of forbidden high ionisation lines (FHIL, e.g. [Fe \textsc{vii}], [Fe \textsc{x}], [Fe \textsc{xi}] and [Ne \textsc{v}]) yet reported for an AGN, as well as unusually strong [O \textsc{iii}]$\lambda$4363 emission. The study of this object provides a rare opportunity to investigate the physical conditions and kinematics of the region(s) emitting the FHILs. By comparison with photoionisation model results, we find that the FHIL region has high densities (10$^{5.5}$ $<$ $n_H$ $<10^{8.0}$ cm\textsuperscript{-3}) and ionisation parameters (-1.5 $<$ log[U] $<$ 0), yet its kinematics are similar to those of the low ionisation emission line region detected in the same object (FWHM $\sim$ 360$\pm$30 km/s), with no evidence for a significant shift between the velocity centroid of the FHILs and the rest frame of the host galaxy. The deduced physical conditions lie between those of the Broad-Line (n$_H$$>10^9$ cm\textsuperscript{-3}) and Narrow-Line Regions ($n_H$$<10^6$ cm\textsuperscript{-3}) of active galactic nuclei (AGN), and we demonstrate that the FHIL regions must be situated relatively close to the illuminating AGN (0.32 $<$ $r_{FHIL}$ $<$ 50pc). We suggest that the inner torus wall is the most likely location for the FHIL region, and that the unusual strength of the FHILs in this object is due to a specific viewing angle of the far wall of the torus, coupled with a lack of dust on larger scales that might otherwise obscure our view of the torus.Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Society (3rd of March 2011). 23 Pages (including tables 5 and 6 in the source file), 21 figure

M-Theory as a Holographic Field Theory

We suggest that M-theory could be non-perturbatively equivalent to a local quantum field theory. More precisely, we present a ``renormalizable'' gauge theory in eleven dimensions, and show that it exhibits various properties expected of quantum M-theory, most notably the holographic principle of 't~Hooft and Susskind. The theory also satisfies Mach's principle: A macroscopically large space-time (and the inertia of low-energy excitations) is generated by a large number of ``partons'' in the microscopic theory. We argue that at low energies in large eleven dimensions, the theory should be effectively described by eleven-dimensional supergravity. This effective description breaks down at much lower energies than naively expected, precisely when the system saturates the Bekenstein bound on energy density. We show that the number of partons scales like the area of the surface surrounding the system, and discuss how this holographic reduction of degrees of freedom affects the cosmological constant problem. We propose the holographic field theory as a candidate for a covariant, non-perturbative formulation of quantum M-theory.Comment: 27 pp. v2: typos corrected; a small paragraph on naturalness of small cosmological constant in four dimensions added at end of sect 5.1; final version to appear in Phys. Rev.

Semi-infinite Throat as the End-state Geometry of two-dimensional Black Hole Evaporation

We study a modified two-dimensional dilaton gravity theory which is exactly solvable in the semiclassical approximation including back-reaction. The vacuum solutions of this modified theory are asymptotically flat static space-times. Infalling matter forms a black hole if its energy is above a certain threshold. The black hole singularity is initially hidden behind a timelike apparent horizon. As the black hole evaporates by emitting Hawking radiation, the singularity meets the shrinking horizon in finite retarded time to become naked. A natural boundary condition exists at the naked singularity such that for general infalling matter-configuration the evaporating black hole geometries can be matched continuously to a unique static end-state geometry. This end-state geometry is asymptotically flat at its right spatial infinity, while its left spatial infinity is a semi-infinite throat extending into the strong coupling region.Comment: Tex + compressed uuencoded ps version with one figure included, 11