Submarine landslide megablocks show half of Anak Krakatau island failed on December 22nd, 2018.

As demonstrated at Anak Krakatau on December 22nd, 2018, tsunamis generated by volcanic flank collapse are incompletely understood and can be devastating. Here, we present the first high-resolution characterisation of both subaerial and submarine components of the collapse. Combined Synthetic Aperture Radar data and aerial photographs reveal an extensive subaerial failure that bounds pre-event deformation and volcanic products. To the southwest of the volcano, bathymetric and seismic reflection data reveal a blocky landslide deposit (0.214 ± 0.036 km3) emplaced over 1.5 km into the adjacent basin. Our findings are consistent with en-masse lateral collapse with a volume ≥0.175 km3, resolving several ambiguities in previous reconstructions. Post-collapse eruptions produced an additional ~0.3 km3 of tephra, burying the scar and landslide deposit. The event provides a model for lateral collapse scenarios at other arc-volcanic islands showing that rapid island growth can lead to large-scale failure and that even faster rebuilding can obscure pre-existing collapse.

Direct quantitative imaging of the writing stage in a photosensitive azopolymer by digital holography.

In this paper, we demonstrated that the gradual formation of a surface relief grating (SRG) in azopolymer thin films under continuous light exposure could be directly observed in situ and in real-time, allowing full-field characterization with high spatial resolution. We reported here for the first time, to the best of our knowledge, that digital holography (DH) can be adopted for investigating and monitoring an inscribed holographic surface relief grating (SRG) of azopolymers by two-beam laser interference lithography over a wide area. The writing process could be assessed through quantitative phase imaging (QPI). The reported results show that the proposed method is a truly valuable diagnostic tool that can be useful for investigating the spatial distribution of the writing process, which can eventually contribute to shedding light on the still unclear origin and related mechanism of SRG formation in azopolymers.

Pyroelectric Effect Enables Simple and Rapid Evaluation of Biofilm Formation.

Biofilms are detrimental to human life and industrial processes due to potential infections, contaminations, and deterioration. Therefore, the evaluation of microbial capability to form biofilms is of fundamental importance for assessing how different environmental factors may affect their vitality. Nowadays, the approaches used for biofilm evaluation are still poor in reliability and rapidity and often provide contradictory results. Here, we present what we call biofilm electrostatic test (BET) as a simple, rapid, and highly reproducible tool for evaluating in vitro the ability of bacteria to form biofilms through electrostatic interaction with a pyroelectrified carrier. The results show how the BET is able to produce viable biofilms with a density 6-fold higher than that on the control, after just 2 h incubation. The BET could pave the way to a rapid standardization of the evaluation of bacterial resistance among biofilm-producing microorganisms. In fact, due to its simplicity and cost-effectiveness, it is well suited for a rapid and easy implementation in a microbiology laboratory.

Easy Printing of High Viscous Microdots by Spontaneous Breakup of Thin Fibers.

Electrohydrodynamic jetting is emerging as a successful technique for printing inks with resolutions well beyond those offered by conventional inkjet printers. However, the variety of printable inks is still limited to those with relatively low viscosities (typically <20 mPa s) due to nozzle clogging problems. Here, we show the possibility of printing ordered microdots of high viscous inks such as poly(lactic-co-glycolic acid) (PLGA) by exploiting the spontaneous breakup of a thin fiber generated through nozzle-free pyro-electrospinning. The PLGA fiber is deposited onto a partially wetting surface, and the breakup is achieved simply by applying an appropriate thermal stimulation, which is able to induce polymer melting and hence a mechanism of surface area minimization due to the Plateau-Rayleigh instability. The results show that this technique is a good candidate for extending the printability at the microscale to high viscous inks, thus extending their applicability to additional applications, such as cell behavior under controlled morphological constraints.

Moral Disengagement and Psychopathy: A Study on Offenders in Italian Jails.

This article investigates mechanisms of moral disengagement and psychopathy in offender detainees (sex offenders and non-sex offenders). In particular, this article investigates whether, in all offenders, moral disengagement and psychopathy are correlated, if there are any differences between sex offenders and non-sex offenders as to psychopathy, and if there are any differences between rapists and child molesters in regard to their levels of psychopathy. The results indicate that, in all offenders, levels of moral disengagement are associated with levels of psychopathy, while sex offenders are more selfish, more insensitive and less remorseful than non-sex offenders. It is also found that rapists display more antisocial behaviour problematic elements in their lifestyle than child molesters. As well as increasing the dedicated literature, studying the mechanisms and characteristics of offenders - and of sex offenders in particular - may be of considerable importance for the promotion of effective and targeted treatment strategies.

Spiral formation at the microscale by µ-pyro-electrospinning.

Spiral shapes occur frequently in nature as in the case of snail shells or the cochlea - the auditory portion of the inner ear. They also inspire many technological devices that take advantage of this geometry. Here we show that µ-pyro-electrospinning is able to control whipping instabilities in order to form spiralling fibres (down to 300 nm thick) directly on a support with true microscale regularity. The results show that polymer concentration plays a key role in producing reliable and long spirals. We investigate the cell response to these spiral templates that, thanks to their true regularity, would be useful for developing innovative cochlea regeneration scaffolds.

Forward electrohydrodynamic inkjet printing of optical microlenses on microfluidic devices.

We report a novel method for direct printing of viscous polymers based on a pyro-electrohydrodynamic repulsion system capable of overcoming limitations on the material type, geometry and thickness of the receiving substrate. In fact, the results demonstrate that high viscosity polymers can be easily manipulated for optical functionalizing of lab-on-a-chip devices through demonstration of direct printing of polymer microlenses onto microfluidic chips and optical fibre terminations. The present system has great potential for applications from biomolecules to nano-electronics. Moreover, in order to prove the effectiveness of the system, the optical performance of such microlenses has been characterized by testing their imaging capabilities when the fibroblast cells were allowed to flow inside the microfluidic channel, showing one of their possible applications on-board a LoC platform.

Active accumulation of very diluted biomolecules by nano-dispensing for easy detection below the femtomolar range.

Highly sensitive detection of biomolecules is of paramount interest in many fields including biomedicine, safety and eco-pollution. Conventional analyses use well-established techniques with detection limits ~1 pM. Here we propose a pyro-concentrator able to accumulate biomolecules directly onto a conventional binding surface. The operation principle is relatively simple but very effective. Tiny droplets are drawn pyro-electro-dynamically and released onto a specific site, thus increasing the sensitivity. The reliability of the technique is demonstrated in case of labelled oligonucleotides diluted serially. The results show the possibility to detect very diluted oligonucleotides, down to a few hundreds of attomoles. Excellent results are shown also in case of a sample of clinical interest, the gliadin, where a 60-fold improved detection limit is reached, compared with standard ELISA. This method could open the way to a mass-based technology for sensing molecules at very low concentrations, in environmental as well as in diagnostics applications.

Spontaneous assembly of carbon-based chains in polymer matrixes through surface charge templates.

Stable chains of carbon-based nanoparticles were formed directly in polymer matrixes through an electrode-free approach. Spontaneous surface charges were generated pyroelectrically onto functionalized ferroelectric crystals, enabling the formation of electric field gradients that triggered the dipole-dipole interactions responsible for the alignment of the particles, while embedded in the polymer solution. The phenomenon is similar to the dielectrophoretic alignment of carbon nanotubes reported in the literature. However, here the electric fields are generated spontaneously by a simple heat treatment that, simultaneously, aligns the particles and provides the energy necessary for curing the host polymer. The result is a polymer sheet reinforced with well-aligned chains of carbon-based particles, avoiding the invasive implementation of appropriate electrodes and circuits. Because polymers with anisotropic features are of great interest for enhancing the thermal and/or the electrical conductivity, the electrode-free nature of this technique would improve the scaling down and the versatility of those interconnections that find applications in many fields, such as electronics, sensors, and biomedicine. Theoretical simulations of the interactions between the particles and the charge templates were implemented and appear in good agreement with the experimental results. The chain formation was characterized by controlling different parameters, including surface charge configuration, particle concentration, and polymer viscosity, thus demonstrating the reliability of the technique. Moreover, micro-Raman spectroscopy and scanning electron microscopy were used for a thorough inspection of the assembled chains.

Graded-size microlens array by the pyro-electrohydrodynamic continuous printing method.

In the present work, the pyro-electrohydrodynamic technique was used for the realization of tunable-size microlens arrays. Poly(methyl methacrylate) dissolved in different solvent mixtures was used as the polymeric material for the realization of the microstructures. By controlling the experimental parameters and in particular, the volume of the drop reservoir, graded-size square arrays of tens of microlenses with focal length in the range 1.5-3 mm were produced. Moreover, the optical quality and geometrical features were investigated by profilometric and interferometric analysis.

Printing of polymer microlenses by a pyroelectrohydrodynamic dispensing approach.

The investigation of a method for fabricating microlenses by a nozzle-free inkjet printing approach is reported. The new method, based on a pyroelectrohydrodynamic mechanism, is also able to dispense viscous liquids and to draw liquid phase drops directly from the reservoir. Specifically, by dispensing optical grade polymer dissolved in different solvent mixtures, microlenses were printed with a pattern defined directly through this deposition method. The reliability of the microlenses and the tunability of their focal properties were demonstrated through profilometric and inteferometric analyses.

Driving and analysis of micro-objects by digital holographic microscope in microfluidics.

We propose an optical configuration in which floating particles in a microfluidic chamber can be characterized by an interference microscopy configuration to obtain quantitative phase-contrast maps. The configuration is simply made by two laser beams from the same laser source. One beam provides the optical forces for driving the particle along appropriate paths, but at same time works as the object illumination beam in the holographic microscope. The second beam plays the role of the reference beam, allowing recording of an interference fringe pattern (i.e., the digital hologram) in an out-of-focus image plane. The system and method are illustrated and experimental results are offered for polymeric particles as well as for in vitro cells with the aim to demonstrate the approach.

Digital self-referencing quantitative phase microscopy by wavefront folding in holographic image reconstruction.

A completely numerical method, named digital self-referencing holography, is described to easily accomplish a quantitative phase microscopy for microfluidic devices by a digital holographic microscope. The approach works through an appropriate numerical manipulation of the retrieved complex wavefront. The self-referencing is obtained by folding the retrieved wavefront in the image plane. The folding operation allows us to obtain the correct phase map by subtracting from the complex region of interest a flat area outside the microfluidic channel. To demonstrate the effectiveness of the method, quantitative phase maps of bovine spermatozoa and in vitro cells are retrieved.

Dispensing nano-pico droplets and liquid patterning by pyroelectrodynamic shooting.

Manipulating and dispensing liquids on the micrometre- and nanoscale is important in biotechnology and combinatorial chemistry, and also for patterning inorganic, organic and biological inks. Several methods for dispensing liquids exist, but many require complicated electrodes and high-voltage circuits. Here, we show a simple way to draw attolitre liquid droplets from one or multiple sessile drops or liquid film reservoirs using a pyroelectrohydrodynamic dispenser. Local pyroelectric forces, which are activated by scanning a hot tip or an infrared laser beam over a lithium niobate substrate, draw liquid droplets from the reservoir below the substrate, and deposit them on the underside of the lithium niobate substrate. The shooting direction is altered by moving the hot tip or laser to form various patterns at different angles and locations. Our system does not require electrodes, nozzles or circuits, and is expected to have many applications in biochemical assays and various transport and mixing processes.

Tunable liquid microlens arrays in electrode-less configuration and their accurate characterization by interference microscopy.

A special class of tunable liquid microlenses is presented here. The microlenses are generated by an electrowetting effect under an electrode-less configuration and they exhibit two different regimes that are named here as separated lens regime (SLR) and wave-like lens regime (WLR). The lens effect is induced by the pyroelectricity of polar dielectric crystals, as was proved in principle in a previous work by the same authors (S. Grilli et al., Opt. Express 16, 8084, 2008). Compared to that work, the improvements to the experimental set-up and procedure allow to reveal the two lens regimes which exhibit different optical properties. A digital holography technique is used to reconstruct the transmitted wavefront during focusing and a focal length variation in the millimetre range is observed. The tunability of such microlenses could be of great interest to the field of micro-optics thanks to the possibility to achieve focus tuning without moving parts and thus favouring the miniaturization of the optical systems.

Super-resolution in digital holography by a two-dimensional dynamic phase grating.

An approach that uses an electro-optically tunable two dimensional phase grating to enhance the resolution in digital holographic microscopy is proposed. We show that, by means of a flexible hexagonal phase grating, it is possible to increase the numerical aperture of the imaging system, thus improving the spatial resolution of the images in two dimensions. The augment of the numerical aperture of the optical system is obtained by recording spatially multiplexed digital holograms. The grating tuneability allows one to adjust the intensity among the spatially multiplexed holograms maximizing the grating diffraction efficiency. Furthermore we demonstrate that the flexibility of the numerical reconstruction allows one to use selectively the diffraction orders carrying useful information for increasing the spatial resolution. The proposed approach can improve the capabilities of digital holography in three-dimensional imaging and microscopy.

Liquid micro-lens array activated by selective electrowetting on lithium niobate substrates.

Lens effect was obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal like LiNbO3. An array of liquid micro-lenses was generated by electrowetting effect in pyroelectric periodically poled crystals. Compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuit-less configuration. An interferometric technique was used to characterize the curvature of the micro-lenses and the corresponding results are presented and discussed. The preliminary results concerning the imaging capability of the micro-lens array are also reported.

Percepción sobre el componente bucal de la salud en docentes de escuelas participantes en la práctica social curricular / Perception on oral health component in school teachers involved in curricular social practice

Bordoni y otros (2006) diseñaron y validaron un cuestionario destinado a estudiar la percepción de actores vinculados con la introducción de intervenciones de salud en escenarios no convencionales del equipamiento social. El objetivo del presente estudio fue identificar las características de percepción sobre el componente bucal de salud en los docentes de escuelas públicas vinculada con experiencias de práctica social curricular de la Universidad de Cuyo y comparar con los resultados obtenidos en un municipio de Bs. As. Material y métodos: los cuestionarios validados incluyen 5 dominios desarrollados en 25 items y las respuestas fueron recabadas aplicando la escala de Likert. Los valores obtenidos en el presente estudio fueron contrastados con la experiencia aplicada con docentes en la Pcia de Bs. As. Resultados: los resultados revelaron que para el dominio conocimientos, el 73,37 por ciento de las entrevistadas alcanzaron un nivel satisfactorio y el 8,12 por ciento resultaron erróneas; para el dominio Experiencia odontológica personal, el 56,87 por ciento tuvo experiencia satisfactoria; al explorar las Expectativas generales respecto a los niños sólo el 42,5 por ciento valoraron como positivo el papel de la familia respecto de la salud; el 45 por ciento expresaron expectativas positivas sobre la odontología. Respecto de su propio papel, la percepción resultó altamente positiva al considerar el item referido a su papel como docente (68,12 por ciento), pero bajo al referirse a su participaicón concreta en programas de salud (33 por ciento). Conclusiones: los resultados permiten concluir que: (a) los conocimientos alcanzaron un nivel satifactorio; (b) existe una percepción negativa referida al papel de los niños/as, las familias y la profesión y a su propio potencial como productor de prácticas de autocuidado. (c) resulta recomendable abordar la solución de los prejuicios existentes antes de incorporar a los docentes a programas de promoción de salud.

Phase map retrieval in digital holography: avoiding the undersampling effect by a lateral shear approach.

In digital holography (DH) the numerical reconstruction of the whole wavefront allows one to extract the wrapped phase map mod, 2 pi. It can occur that the reconstructed wrapped phase map in the image plane is undersampled because of the limited pixel size in that plane. In such a case the phase distribution cannot be retrieved correctly by the usual unwrapping procedures. We show that the use of the digital lateral-shearing interferometry approach in DH provides the correct reconstruction of the phase map in the image plane, even in extreme cases where the phase profile changes very rapidly. We demonstrate the effectiveness of the method in a particular case where the profile of a highly curved silicon microelectromechanical system membrane has to be reconstructed.

Quantitative Phase Microscopy of microstructures with extended measurement range and correction of chromatic aberrations by multiwavelength digital holography.

Quantitative Phase Microscopy (QPM) by interferometric techniques can require a multiwavelength configuration to remove 2pi ambiguity and improve accuracy. However, severe chromatic aberration can affect the resulting phase-contrast map. By means of classical interference microscope configuration it is quite unpractical to correct such aberration. We propose and demonstrate that by Digital Holography (DH) in a microscope configuration it is possible to clear out the QPM map from the chromatic aberration in a simpler and more effective way with respect to other approaches. The proposed method takes benefit of the unique feature of DH to record in a plane out-of-focus and subsequently reconstruct numerically at the right focal image plane. In fact, the main effect of the chromatic aberration is to shift differently the correct focal image plane at each wavelength and this can be readily compensated by adjusting the corresponding reconstruction distance for each wavelength. A procedure is described in order to determine easily the relative focal shift among different imaging wavelengths by performing a scanning of the numerical reconstruction along the optical axis, to find out the focus and to remove at the same time the chromatic aberration.